Metal status in human endometrium: Relation to cigarette smoking and histological lesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rzymski, Piotr, E-mail: rzymskipiotr@ump.edu.pl; Rzymski, Paweł; Tomczyk, Katarzyna

Human endometrium is a thick, blood vessel-rich, glandular tissue which undergoes cyclic changes and is potentially sensitive to the various endogenous and exogenous compounds supplied via the hematogenous route. As recently indicated, several metals including Cd, Pb, Cr and Ni represent an emerging class of potential metalloestrogens and can be implicated in alterations of the female reproductive system including endometriosis and cancer. In the present study, we investigated the content of five metals: Cd, Cr, Ni, Pb and Zn in 25 samples of human endometrium collected from Polish females undergoing diagnostic or therapeutic curettage of the uterine cavity. The overallmore » mean metal concentration (analyzed using microwave induced plasma atomic emission spectrometry MIP-OES) decreased in the following order: Cr>Pb>Zn>Ni>Cd. For the first time it was demonstrated that cigarette smoking significantly increases the endometrial content of Cd and Pb. Concentration of these metals was also positively correlated with years of smoking and the number of smoked cigarettes. Tissue samples with recognized histologic lesions (simple hyperplasia, polyposis and atrophy) were characterized by a 2-fold higher Cd level. No relation between the age of the women and metal content was found. Our study shows that human endometrium can be a potential target of metal accumulation within the human body. Quantitative analyses of endometrial metal content could serve as an additional indicator of potential impairments of the menstrual cycle and fertility. - Highlights: • Cd, Cr, Ni, Pb and Zn are detectable in human endometrium. • Mean metal content in human endometrium decreases in Cr>Pb>Zn>Ni>Cd order. • Cigarettes smoking increases endometrial content of Cd and Pb. • Lesioned endometrial tissue was characterized by higher metal contents.« less

[Spatial distribution and pollution assessment of heavy metals in the tidal reach and its adjacent sea estuary of Daliaohe area, China ].

PubMed

Zhang, Lei; Qin, Yan-wen; Ma, Ying-qun; Zhao, Yan-min; Shi, Yao

2014-09-01

The aim of this article was to explore the pollution level of heavy metals in the tidal reach and its adjacent sea estuary of Daliaohe area. The contents and spatial distribution of As, Cd, Cr, Cu, Ph and Zn in surface water, suspended solids and surface sediments were analyzed respectively. The integrated pollution index and geoaccumulation index were used to evaluate the contamination degree of heavy metals in surface water and surface sediments respectively. The results indicated that the contents of heavy metals in surface water was in the order of Pb < Cu < Cd < Cr < As < Zn. The heavy metal contents in surface water increased from river to sea. Compared with the contents of heavy metals in surface water of the typical domestic estuary in China, the overall contents of heavy metals in surface water were at a higher level. The contents of heavy metals in suspended solids was in the order of Cd < Cu < As < Cr

Ecological risk assessment of a coastal zone in Southern Vietnam: Spatial distribution and content of heavy metals in water and surface sediments of the Thi Vai Estuary and Can Gio Mangrove Forest.

PubMed

Costa-Böddeker, Sandra; Hoelzmann, Philipp; Thuyên, Lê Xuân; Huy, Hoang Duc; Nguyen, Hoang Anh; Richter, Otto; Schwalb, Antje

2017-01-30

Enrichment of heavy metals was assessed in the Thi Vai Estuary and in the Can Gio Mangrove Forest (SE, Vietnam). Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn contents in water and in sediments were measured. Total organic carbon, nitrogen, phosphorus and C/N ratios were determined. Cu and Cr values were higher than threshold effect level of toxicity, while Ni exceeded probable effect level, indicating the risk of probable toxicity effects. Enrichment factors (EF), contamination factor (CF) and Geo-accumulation index (I-geo) were determined. CF reveals moderate to considerable pollution with Cr and Ni. EF suggests anthropogenic sources of Cr, Cu and Ni. I-geo indicates low contamination with Co, Cu and Zn and moderate contamination with Cr and Ni. Overall metal contents were lower than expected for this highly industrialized region, probably due to dilution, suggesting that erosion rates and hydrodynamics may also play a role in metal contents distribution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of microstructure on stress corrosion cracking of alloy 600 and alloy 690 in 40% NaOH

NASA Astrophysics Data System (ADS)

Kim, H. P.; Hwang, S. S.; Lim, Y. S.; Kuk, I. H.; Kim, J. S.

2001-02-01

Stress corrosion cracking (SCC) behaviors of Alloy 600, Alloy 690 and the Ni-10Cr-10Fe alloy have been studied using a C-ring in 40% NaOH solution at 315°C. The current density of Alloy 690 in polarization curves was higher at 200 mV above corrosion potential than that of Alloy 600. SCC resistance increased with Cr content for the chromium carbide free alloys, probably due to facilitation of SCC crack tip blunting with an increase in Cr content. Both thermally treated Alloy 600 and sensitized Alloy 600 have a comparable amount of intergranular carbide. But the former is more resistant to SCC than the latter, which might be attributed to the presence of the slight Cr depletion around the grain boundary in the former one. Sensitized Alloy 600 showed higher SCC resistance than the solution annealed one due to intergranular carbide in sensitized Alloy 600. This implies that the beneficial effect of intergranular carbide overrides the harmful effects of Cr depletion for sensitized Alloy 600. SCC resistance of Alloy 600 increased with grain size.

Bioaccumulation of Copper (Cu) and Chromium (Cr) on export comodity vanamei shrimp from Karawang, West Java

NASA Astrophysics Data System (ADS)

Rahman, A.; Takarina, N. D.; Siswantining, T.; Pin, T. G.; Soedjiarti, T.

2018-05-01

Karawang is one of regencies in West Java which has great potential for vannamei culture. The farm here was modern farm and using Citarum River as water source. Human activities like household and industry around the river cause its quality decrease and give negative impact to shrimp farm. This research was aimed to investigate the bioaccumulation of copper (Cu) and chromium (Cr) on vannamei shrimp from Karawang, West Java. Amount of shrimp’s meat and carapace were used for heavy metal measurement using Atomic Absorption Specthrophotometry. Result showed that contents of copper both in meat and carapace were higher than content of chromium. Moreover, the content of both metals was higher on carapace compared to meat. Since the content of meat were below threshold, so it is safe for consumption. There is no significant difference content of both metals in carapace.

Effect of Cr-N codoping on structural phase transition, Raman modes, and optical properties of TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Hassnain Jaffari, G.; Tahir, Adnan; Ali, Naveed Zafar; Ali, Awais; Qurashi, Umar S.

2018-04-01

Noncompensated cation-anion codoping in TiO2 nanoparticles has been achieved by a chemical synthesis route. Significant reduction in the optical bandgap and enhancement in the absorption of visible light have been observed. Structural phase transformation has been tracked in detail as a function of doping and heat treatment temperature. Anatase to rutile phase transition temperature for doped samples was higher in comparison to the pure TiO2 nanoparticles. Nitrogen and chromium addition increases the phase transformation barrier, where the effect of the former dopant is of more significance. The Raman results showed an increase in the oxygen content with higher post annealing temperatures. With Cr incorporation, the peak associated with the Eg mode has been found to shift towards a higher wave number, while with nitrogen incorporation, the shift was towards a lower wave number. A decrease in reflectance with N co-doping for all samples, irrespective of phase and annealing temperatures, has been observed. In compositions with nitrogen of the same content, bandgap reduction was higher in the rutile phase in comparison to the anatase phase. In general, overall results revealed that with a higher loading fraction of ammonia, the N content increases, while Cr addition prevents nitrogen loss even up to high post annealing temperatures, i.e., 850 °C.

Ecological and human health risks from metal(loid)s in peri-urban soil in Nanjing, China.

PubMed

Ding, Zhuhong; Hu, Xin

2014-06-01

In order to investigate the ecological and human health risks of metal(loid)s (Cu, Pb, Zn, Ni, Cd, Mn, Cr, and As) in peri-urban soils, 43 surface soil samples were collected from the peri-urban area around Nanjing, a megacity in China. The average contents were 1.19, 67.8, 37.6, 105, 167, 44.6, 722, and 50.8 mg kg(-1) for Cd, Cr, Ni, Pb, Zn, Cu, Mn, and As, respectively. A significant positive correlation was found between Cu, Pb, Zn, Cd, Mn, and As (p < 0.01), and Cr had a significant positive correlation with Ni (p < 0.01). Geoaccumulation indices indicate the presence of Cd and As contamination in all of the peri-urban soil samples. Potential ecological risk indices show that the metal(loid)s in the soil could result in higher ecological risks. Cd is the main contributor to the risk, followed by As. The levels of Cu, Pb, Zn, Cd, Mn, and As in stomach and intestinal phases show a positive linear correlation with their total contents. Mn, Zn, Ni, Cd, and Pb in stomach phase showed higher bioaccessibility, while in intestinal phase, Cu, Cr, and As had the higher bioaccessibility. The carcinogenic risk in children and adults posed by As, Pb, and Cr via ingestion was deemed acceptable. The non-carcinogenic risks posed by these metal(loid)s via ingestion to children are higher than to adults and mainly result from As.

Changes of chromium speciation and organic matter during low-temperature pyrolysis of tannery sludge.

PubMed

Zhou, Jianjun; Ma, Hongrui; Gao, Mao; Sun, Wenyue; Zhu, Chao; Chen, Xiangping

2018-01-01

The application or disposal of char derived from tannery sludge is directly influenced by the mobility and bioavailability of Cr during pyrolysis process. This study focused on the changes of Cr speciation and organic matter in tannery sludge during low-temperature pyrolysis (100-400 °C) to evaluate the toxicity of char in terms of the leaching possibility of Cr. The results showed that (1) lower char yield and more porous structure were observed after pyrolysis. (2) Higher pyrolysis temperature increased Cr content in the char; however, Cr in this case was converted into the residual fraction which minimized its bioavailability therefore lowers its potential risk to the environment. (3) Organic matters in the acid and alkali leachates were mainly humic acid-like substance, and condensed organic matter might appear at 200 °C and then destruct. (4) Despite the comparatively high content of Cr in the char, the leaching toxicity of char was within the security range according to the national standard of China. The Cr content in the acid and alkali leachates decreased to the range of 16.5-35.3 and 0.2-6.8 mg/L, respectively. It was suggested that the potential toxicity of tannery sludge from Cr could be reduced before utilization or disposal by pyrolysis, especially under 400 °C.

High-Temperature Oxidation Behavior of Al-Co-Cr-Ni-(Fe or Si) Multicomponent High-Entropy Alloys

NASA Astrophysics Data System (ADS)

Butler, T. M.; Alfano, J. P.; Martens, R. L.; Weaver, M. L.

2015-01-01

High-entropy alloys (HEAs) are a class of alloys that are being considered for a number of applications. In the present study, the microstructures and 1050°C oxidation behaviors of two HEAs, Al10Cr22.5Co22.5Ni22.5Fe22.5 (at.%) and Al20Cr25Co25Ni25Si5 have been investigated along with Al15Cr10Co35Ni35Si5, which is a high-temperature shape-memory alloy. Oxide formation occurred via selective oxidation in a manner that was consistent with the oxide formation model devised by Giggins and Pettit for model Ni-Cr-Al alloys. The lower Al content alloy formed an external Cr2O3 scale and an internal subscale consisting of Al2O3 and AlN precipitates. The higher Al content alloys exhibited smaller mass gains and formed external Al2O3 scales without any internal oxidation of the alloys.

Phenolics composition and antioxidant activity of wine produced from spine grape (Vitis davidii Foex) and Cherokee rose (Rosa laevigata Michx.) fruits from South China.

PubMed

Meng, Jiangfei; Fang, Yulin; Gao, Jinshan; Qiao, Lingling; Zhang, Ang; Guo, Zhijun; Qin, Minyang; Huang, Jizhuang; Hu, Ying; Zhuang, Xifu

2012-01-01

Wines made from 3 spine grape (Vitis davidii Foex) genotypes-Junzi 1# (JZ 1#), Junzi 2# (JZ 2#), and Liantang (LT)-and Cherokee rose (Rosa laevigata Michx., CR) were evaluated for their phenolics composition and antioxidant activities by several assays, including 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS scavenging capacity, cupric ion reducing antioxidant capacity, and metal-chelating capacity). The results showed that CR wine had higher contents of total phenolics, total flavonoids, and oligomeric proanthocyanidins than the 3 spine grape genotype wines and Cabernet Sauvignon (CS) wine. Among the 3 varieties of spine grape wines, JZ 1# had higher contents than the 2 other genotypes. Moreover, the total monomeric anthocyanins in JZ 1# was about 4.5-fold higher than those in CS wine and CR wine. A significance analysis demonstrated that the antioxidant capacity (as measured by the ABTS scavenging capacity and cupric ion reducing antioxidant capacity) of CR wine was significantly higher than that of the control and spine grape wines. With respect to metal-chelating capacity, the CR wine was the strongest amongst all the wine samples tested, followed by JZ 1#. This indicates that CR and JZ 1# wines can potentially be considered as wild fruit wines with abundant phenolic compounds and antioxidant activities. Spine grape (Vitis davidii Foex) and Cherokee rose (Rosa laevigata Michx.) are 2 species of important wild plants in South China. However, they have not yet been effectively developed and utilized. Recently, some researchers attempted to convert their juice to wine. We anticipate that this research will provide sufficient experimental evidence for their good antioxidant activity and potential for further development and utilization. © 2011 Institute of Food Technologists®

Preliminary assessment of metal-porcelain bonding strength of CoCrW alloy after 3wt.% Cu addition.

PubMed

Lu, Yanjin; Zhao, Chaoqian; Ren, Ling; Guo, Sai; Gan, Yiliang; Yang, Chunguang; Wu, Songquan; Lin, Junjie; Huang, Tingting; Yang, Ke; Lin, Jinxin

2016-06-01

In this work, a novel Cu-bearing CoCrW alloy fabricated by selective laser melting for dental application has been studied. For its successful application, the bonding strength of metal-porcelain is essential to be systematically investigated. Therefore, the aim of this study was to evaluate the metal-porcelain bonding strength of CoCrWCu alloy by three-point bending test, meanwhile the Ni-free CoCrW alloy was used as control. The oxygen content was investigated by an elemental analyzer; X-ray photoelectron spectroscopy (XPS) was used to analyze the surface chemical composition of CoCrW based alloy after preoxidation treatment; the fracture mode was investigated by X-ray energy spectrum analysis (EDS) and scanning electron microscope (SEM). Result from the oxygen content analysis showed that the content of oxygen dramatically increased after the Cu addition. And the XPS suggested that Co-oxidation, Cr2O3, CrO2, WO3, Cu2O and CuO existed on the preoxidated surface of the CoCrWCu alloy; the three-point bending test showed that the bonding strength of the CoCrWCu alloy was 43.32 MPa, which was lower than that of the CoCrW group of 47.65 MPa. However, the average metal-porcelain bonding strength is significantly higher than the minimum value in the ISO 9693 standard. Results from the SEM images and EDS indicated that the fracture mode of CoCrWCu-porcelain was mixed between cohesive and adhesive. Based on the results obtained in this study, it can be indicated that the Cu-bearing CoCrW alloy fabricated by the selective laser melting is a promising candidate for use in dental application. Copyright © 2016 Elsevier B.V. All rights reserved.

Phytoremediation potential of chromium-containing tannery effluent-contaminated soil by native Indian timber-yielding tree species.

PubMed

Manikandan, Muthu; Kannan, Vijayaraghavan; Mahalingam, Kanimozhi; Vimala, A; Chun, Sechul

2016-01-01

Twenty-six native Indian tree species that are used for the enhanced tree cover program of the forest department (Government of Tamilnadu, India) were screened for phytoremediation of tannery effluent-contaminated soil containing high chromium content. Out of 26 tree species tested, 10 timber-yielding tree species were selected for further phytoremediation monitoring. After a series of treatments with tannery effluent sludge, the chromium content was measured in the plant parts. The saplings of Acacia auriculiformis, Azadirachta indica, Albizzia lebbeck, Dalbergia sisso, and Thespesia populnea were identified as efficient bioaccumulators of chromium from Cr-contaminated soil. Acacia auriculiformis accumulates higher amounts of Cr in both the root and stem. Dalbergia sisso and T. populnea were found to accumulate higher quantity of Cr in the roots, whereas A. indica, A. richardiana, and A. lebbeck accumulate Cr in their stem. The stress response of the plant species was assessed by quantifying the antioxidative enzymes such as catalase, superoxide dismutase, glutathione reductase, and DHAR. Activity of all the enzymes was observed to gradually increase following treatment with tannery effluent sludge.

[Determination of 22 inorganic elements in different parts of Lantana camara by ICP-OES].

PubMed

Zhou, Wei-ming; Wang, Ru-yi; Chen, Liu-sheng; Huang, Chuan-bin

2014-10-01

To determine the contents of 22 inorganic elements in different parts of Lantana camara by inductively coupled plasma optical emission spectroscopy (ICP-OES). HNO3-H2O2 digested system was used to completely decompose the organic compounds effectually by microwave digestion. The 22 inorganic elements such as K, Ca, Mg, Fe, Al, Na, Zn, Mn and Cr were determined by ICP-OES under set up working conditions. The contents of K, Ca and Mg were the most in different parts of Lantana camara; The contents of K, Ca, Mg, Mn, Sr and Cu in the leaf were more those that in the root and branch; The contents of Fe, Na, Cr and Ni in the root were more than those in the leaf and branch; The contents of Mn, Zn, Sr and Cu in the branch were more than those in the root and the leaf; The contents of Pb and Cd were higher than the national standard and Cr had high content in different parts of Lantana camara. The determination method is quick, easy and accurate with high sensitivity, which can determine the contents of 22 inorganic elements accurately in different parts of Lantana camara.

The effect of variations of cobalt content on the cyclic oxidation resistance of selected Ni-base superalloys

NASA Technical Reports Server (NTRS)

Barrett, Charles A.

1987-01-01

Cobalt levels were systematically varied in the Ni-base turbine alloys U-700 (cast), U-700m (PM/HIP), Waspaloy, Mar-M-247, In-738, Nimonic-115, U-720, and SX-R-150. the cobalt levels ranged from 0 wt pct to the nominal commercial content in each alloy. the alloys were tested in cyclic oxidation in static air at 1000, 1100 and 1150 C for 500, 200, and 100 hr, respectively. An oxidation attack parameter, Ka, derived from the specific weight change versus time data was used to evaluate the oxidation behavior of the alloys along with X-ray diffraction analysis of the surface oxides. The alloys tend to form either Cr2O3/chromite spinel or Al2O3/aluminate spinel depending on the Cr/Al ratio in the alloys. Alloys with a ratio of 3.5 or higher tend to favor the Cr oxides while those under 3.0 form mostly Al oxides. In general the Al2O3/aluminate spinel forming alloys have the better oxidation resistance. Increased cobalt content lowers the scaling resistance of the higher Cr allys while a 5.0 wt pct Co content is optimum for the Al controlling alloys. The refractory metals, particularly Ta, appear beneficial to both types of oxides, perhaps due to the formation of the omnipresent trirutile Ni(Ta, Cb, Mo, W)2O6. Both scales break down as increasing amounts of NiO are formed.

[Spatial distribution and ecological risk assessment of heavy metals in the estuaries surface sediments from the Haihe River Basin].

PubMed

Lü, Shu-Cong; Zhang, Hong; Shan, Bao-Qing; Li, Li-Qing

2013-11-01

It is well known that the rivers in the Haihe River Basin have been seriously polluted. However, what is the present condition of the estuary pollution and how the polluted inland rivers affect the estuary areas are not clear. 10 main estuaries of the Haihe River Basin were selected to measure the contents of typical heavy metals (Pb, Cu, Zn, Cd, Cr and Ni) in the surface sediments and to analyze the spatial distribution of these heavy metals. The potential ecological risk index was used to assess the ecological risk of the six heavy metals in the estuaries. The results showed that the contents of Pb, Cu, Zn, Cd, Cr and Ni in the surface sediments of the 10 estuaries were all higher than their background values in the main local soil types and the contents of Cu, Ni and Pb were 2.3-2.6 times as high as their background values, which indicated that the estuaries were contaminated by the six heavy metals. The results also indicated that the contents of the six heavy metals in surface sediment varied from one estuary to another. The four heavy metals of Cr, Cu, Ni and Zn had bigger spatial differences than Pb and Cd in the contents in sediment from different estuaries. The contents of Cr, Cu, Ni and Zn in sediment were higher in the estuaries of the Yongdingxin River, Ziyaxin River and Beipai River than those in the other estuaries, and there were significant correlations between each other (R(Cu-Zn) = 0.891, R(Cu-Cr) = 0.927, R(Cu-Ni) = 0.964, R(Zn-Cr) = 0.842, R(Zn-Ni) = 0.939, and R(Cr-Ni) = 0.879, P < 0.01), which indicated that they possibly came from the same sources. Moreover, the contents of Cr, Cu, Ni and Zn in sediment also had significant correlations with the populations of sub-river basins with correlation coefficients of 0.855, 0.806, 0.867 and 0.855 (P < 0.01), respectively. The contents of Cd and Pb had smaller spatial differences in sediment from different estuaries than the other heavy metals, with the values ranged 23.3-95.8 mg x kg(-1) and 0.051-0.200 mg x kg(-1). Contents of the two heavy metals had no significant correlation with the other heavy metals or with the populations of sub-river basins, indicating that Cd and Pb had little connection with the in-land polluted sources. The results of ecological risk assessment showed that estuaries of the Haihe River Basin had the potential ecological risk at lower levels (RI were 33.7-116) and the most important contaminating element was Cd with a middle-level potential ecological risk (Er(i) were 18.0-48.9).

Oxidation of Cr(III)-Fe(III) Mixed-phase Hydroxides by Chlorine: Implications on the Control of Hexavalent Chromium in Drinking Water.

PubMed

Chebeir, Michelle; Liu, Haizhou

2018-05-17

The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation. Data showed that an increase in Fe(III) molar content resulted in a significant decrease in the stoichiometric Cr(VI) yield and the rate of Cr(VI) formation, mainly due to chlorine decay induced by Fe(III) surface sites. An increase in bicarbonate enhanced the rate of Cr(VI) formation, likely due to the formation of Fe(III)-carbonato surface complexes that slowed down the scavenging reaction with chlorine. The presence of bromide significantly accelerated the oxidation of FexCr(1-x)(OH)3(s) by chlorine, resulting from the catalytic effect of bromide acting as an electron shuttle. A higher solution pH between 6 and 8.5 slowed down the oxidation of Cr(III) by chlorine. These findings suggested that the oxidative conversion of chromium-containing iron corrosion products in drinking water distribution systems can lead to the occurrence of Cr(VI) at the tap, and the abundance of iron, and a careful control of pH, bicarbonate and bromide levels can assist the control of Cr(VI) formation.

Exploratory studies of the potential anti-cancer effects of creatine.

PubMed

Campos-Ferraz, P L; Gualano, B; das Neves, W; Andrade, I T; Hangai, I; Pereira, R T S; Bezerra, R N; Deminice, R; Seelaender, M; Lancha, A H

2016-08-01

Two experiments were performed, in which male Wistar Walker 256 tumor-bearing rats were inoculated with 4 × 10(7) tumor cells subcutaneously and received either creatine (300 mg/kg body weight/day; CR) or placebo (water; PL) supplementation via intragastric gavage. In experiment 1, 50 rats were given PL (n = 22) or CR (n = 22) and a non-supplemented, non-inoculated group served as control CT (n = 6), for 40 days, and the survival rate and tumor mass were assessed. In experiment 2, 25 rats were given CR or PL for 15 days and sacrificed for biochemical analysis. Again, a non-supplemented, non-inoculated group served as control (CT; n = 6). Tumor and muscle creatine kinase (CK) activity and total creatine content, acidosis, inflammatory cytokines, and antioxidant capacity were assessed. Tumor growth was significantly reduced by approximately 30 % in CR when compared with PL (p = 0.03), although the survival rate was not significantly different between CR and PL (p = 0.65). Tumor creatine content tended to be higher in CR than PL (p = 0.096). Tumor CK activity in the cytosolic fraction was higher in CR than PL (p < 0.0001). Blood pCO2 was higher in CT and CR than PL (p = 0.0007 and p = 0.004, respectively). HCO3 was augmented in CT compared to PL (p = 0.03) and CR (p = 0.001). Plasma IL-6 was lower and IL-10 level was higher in CR than PL (p = 0.03 and p = 0.0007, respectively) and TNF-alpha featured a tendency of decrease in CR compared to PL (p = 0.08). Additionally, total antioxidant capacity tended to be lower in CT than PL (p = 0.07). Creatine supplementation was able to slow tumor growth without affecting the overall survival rate, probably due to the re-establishment of the CK-creatine system in cancer cells, leading to attenuation in acidosis, inflammation, and oxidative stress. These findings support the role of creatine as a putative anti-cancer agent as well as help in expanding our knowledge on its potential mechanisms of action in malignancies.

Performance of rose scented geranium (Pelargonium graveolens) in heavy metal polluted soil vis-à-vis phytoaccumulation of metals.

PubMed

Chand, Sukhmal; Singh, Geetu; Patra, D D

2016-08-02

An investigation was carried out to evaluate the effect of heavy metal toxicity on growth, herb, oil yield and quality and metal accumulation in rose scented geranium (Pelargonium graveolens) grown in heavy metal enriched soils. Four heavy metals (Cd, Ni, Cr, and Pb) each at two levels (10 and 20 mg kg-1 soil) were tested on geranium. Results indicated that Cr concentration in soil at 20 mg kg-1 reduced leaves, stem and root yield by 70, 83, and 45%, respectively, over control. Root growth was significantly affected in Cr stressed soil. Nickel, Cr, and Cd concentration and accumulation in plant increased with higher application of these metals. Chromium, nickel and cadmium uptake was observed to be higher in leaves than in stem and roots. Essential oil constituents were generally not significantly affected by heavy metals except Pb at 10 and 20 ppm, which significantly increased the content of citronellol and Ni at 20 ppm increased the content of geraniol. Looking in to the higher accumulation of toxic metals by geranium and the minimal impact of heavy metals on quality of essential oil, geranium can be commercially cultivated in heavy metal polluted soil for production of high value essential oil.

Sorption of chromium with struvite during phosphorus recovery.

PubMed

Rouff, Ashaki A

2012-11-20

Struvite (MgNH(4)PO(4)·6H(2)O; MAP) precipitation is a viable means of phosphorus (P) recovery from animal and human wastes. The behavior of metal contaminants such as chromium (Cr) during struvite precipitation, however, requires consideration. Here the influence of both Cr concentration and oxidation state on sorption is assessed. The Cr content of struvite precipitated in the presence of 1-100 μM Cr as Cr(III) (22.3-3030.1 mg/kg) was higher than that of solids from Cr(VI) (4.5-5.1 mg/kg) solutions. For 1-20 μM Cr(III) solids, scanning electron microscopy (SEM) revealed etch pit formation on struvite crystal surfaces, indicative of a surface interaction. The formation of an adsorbate was confirmed by X-ray absorption fine structure spectroscopy (XAFS). At initial concentrations ≥20 μM Cr(III), XAFS confirmed the formation of a Cr(OH)(3)·nH(2)O(am) precipitate. Fourier transform infrared (FT-IR) spectroscopy revealed that both Cr(III) and Cr(VI) sorption resulted in distortion of the PO(4)(3-) tetrahedra in the mineral structure. This, combined with SEM results revealed that even at low sorbed concentrations, the Cr impurity can affect the mineral surface and structure. Thus, the initial Cr concentration and oxidation state in wastes targeted for P recovery will dictate the final Cr content, the mechanism of sorption, and impact on the struvite structure.

The effect of different anti-solvent and coconut shell content on properties of coconut shell regenerated cellulose biocomposite films

NASA Astrophysics Data System (ADS)

Hahary, Farah Norain; Husseinsyah, Salmah; Mostapha@Zakaria, Marliza

2016-07-01

In this study, coconut shell (CS) regenerated cellulose (RC) biocomposite films was prepared using dimethylacetamide/lithium chloride (DMAc/LiCl) solvent system. The effect of anti-solvents such as water and methanol for regeneration of cellulose and coconut shell content on properties of CS-RC biocomposite films was investigated. The used of water as anti-solvent for cellulose regeneration was found to have higher tensile properties compared to regenerated cellulose using methanol. Besides, the X-Ray diffraction (XRD) analysis also revealed that RC using water as anti-solvent have higher crystallinity index (CrI) than CS-RC biocomposite film using methanol. The tensile strength and modulus elasticity of CS-RC biocomposite films increased up to 3 wt% CS and decreased with further addition of CS. The elongation at break of CS-RC biocomposite films decreased with the increment of CS. The CrI of CS-RC bioocmposite films up to 3 wt% and decreased with at higher content of CS.

Neutron irradiation effects in Fe and Fe-Cr at 300 °C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei-Ying; Miao, Yinbin; Gan, Jian

2016-06-01

Fe and Fe-Cr (Cr = 10–16 at.%) specimens were neutron-irradiated at 300 °C to 0.01, 0.1 and 1 dpa. The TEM observations indicated that the Cr significantly reduced the mobility of dislocation loops and suppressed vacancy clustering, leading to distinct damage microstructures between Fe and Fe-Cr. Irradiation-induced dislocation loops in Fe were heterogeneously observed in the vicinity of grown-in dislocations, whereas the loop distribution observed in Fe-Cr is much more uniform. Voids were observed in the irradiated Fe samples, but not in irradiated Fe-Cr samples. Increasing Cr content in Fe-Cr results in a higher density, and a smaller size ofmore » irradiation-induced dislocation loops. Orowan mechanism was used to correlate the observed microstructure and hardening, which showed that the hardening in Fe-Cr can be attributed to the formation of dislocation loops and α' precipitates.« less

Mineral Composition of Wild and Cultivated Blueberries.

PubMed

Dróżdż, Paulina; Šėžienė, Vaida; Pyrzynska, Krystyna

2018-01-01

The concentrations of 13 elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn) were determined in several samples of native (wild) naturally growing and cultivated blueberry fruits. The total metal contents after mineralization were analyzed by inductively coupled plasma optical emission spectrometry. Reliability of the procedure was checked by the analysis of the certified reference materials Mixed Polish Herbs (INGT-MPH-2) and Leaves of Poplar (NCS DC 73350). In the fruits collected in the forest (wild blueberries), higher contents of Ca, Na, and Mg as well as Mn and Zn were observed. Similar levels of Cu, Cr, Fe, and Ni were detected in both wild-growing and cultivated plants. The significantly higher content of Fe and Cd in cultivated blueberries was connected with the content of these metals in soil samples collected from the same places. The metal extraction efficiency by hot water varied widely for the different blueberries (wild or cultivated) as well as their form (fresh or dried).

Accumulation and distribution of trivalent chromium and effects on hybrid willow (Salix matsudana Koidz x alba L.) metabolism.

PubMed

Yu, X-Z; Gu, J-D

2007-05-01

The metabolic response of plants to exogenous supply and bioaccumulation of trivalent chromium (Cr(3+) ) was investigated. Pre-rooted young hybrid willows (Salix matsudana Koidz x alba L.) were exposed to hydroponic solution spiked with CrCl(3) at 24.0 degrees C +/- 1 degrees C for 192 hours. Various physiologic parameters of the plants were monitored to determine toxicity from Cr exposure. The transpiration rate of willows exposed to 2.5 mg Cr/L was 49% higher than that of the untreated control plants, but it was decreased by 17% when exposed to 30.0 mg Cr/L. Significant decrease (> or =20%) of soluble protein in young leaves of willows was detected in the treatment group with > or =7.5 mg Cr/L. The measured chlorophyll contents in leaves of treated plants varied with the dose of Cr, but a linear correlation could not be established. The contents of chlorophyll in leaves of willows exposed to > or =7.5 mg Cr/L were higher than that of the untreated plants but lower at 30.0 mg Cr/L. Superoxide dismutase activity (SOD) in leaves between the treated and untreated willows did not show any significant difference, but activities of both catalase (CAT) and peroxidase (POD) in leaf cells of all treated plants were higher than those in the untreated willows. The correlation between the concentration of Cr and CAT activity in leaf cells was the highest of all toxicity assays (R ( 2 ) = 0.9096), indicating that CAT activity was most sensitive to the change in Cr(3+) doses compared with the other selected parameters. Results from the Cr uptake study showed that significant removal of Cr from hydroponic solution was observed in the presence of hybrid willows without showing detectable phytotoxicity, even at high does of Cr. More than 90% of the applied Cr(3+) was removed from the aqueous solution by willows at concentrations up to 7.5 mg Cr/L. Approximately 70% of the initial Cr was recovered in the plant materials. At the low-Cr(3+) treatment (2.5 mg Cr/L), Cr accumulation by willow materials was the greatest (92%) in roots and the lowest (0.2%) in leaves, whereas the greatest (66%) was in stems and the lowest (0.1%) in leaves of willows exposed to 30.0 mg Cr/L. The correlation between applied Cr(3+) (mg Cr/L) and Cr (mug Cr/g fresh weight [fw]) accumulated in plant materials was significant. The bioaccumulation kinetics of Cr by hybrid willows can be described by a typical saturation curve. Results also indicated that translocation of Cr from roots to shoots was possible. It is to conclude that hybrid willows have great potential as bioremediation technology in the removal of chromium (Cr(3+)) from contaminated effluents and sediments.

Influence of Feedstock Materials and Spray Parameters on Thermal Conductivity of Wire-Arc-Sprayed Coatings

NASA Astrophysics Data System (ADS)

Yao, H. H.; Zhou, Z.; Wang, G. H.; He, D. Y.; Bobzin, K.; Zhao, L.; Öte, M.; Königstein, T.

2017-03-01

To manufacture a protective coating with high thermal conductivity on drying cylinders in paper production machines, a FeCrB-cored wire was developed, and the spraying parameters for wire-arc spraying were optimized in this study. The conventional engineering materials FeCrAl and FeCrMo coatings were produced as the reference coatings under the same experimental condition. It has been shown that the oxide content in coating influences the thermal conductivity of coating significantly. The FeCrB coating exhibits a relative higher thermal conductivity due to the lower oxide content in comparison with conventional FeCrAl and FeCrMo coatings. Moreover, the oxidation of in-flight particles can be reduced by decreasing the standoff distance contributing to the increase in the thermal conductivity of coating. Total energy consumption of a papermaking machine can be significantly reduced if the coatings applied to dryer section exhibit high thermal conductivity. Therefore, the FeCrB coating developed in this study is a highly promising coating system for drying cylinders regarding the improved thermal conductivity and low operation costs in paper production industry.

Late-maturing cooking rice Sensyuraku has excellent properties, equivalent to sake rice, for high-quality sake brewing.

PubMed

Anzawa, Yoshihiko; Satoh, Kenji; Satoh, Yuko; Ohno, Satomi; Watanabe, Tsutomu; Katsumata, Kazuaki; Kume, Kazunori; Watanabe, Ken-Ichi; Mizunuma, Masaki; Hirata, Dai

2014-01-01

Low protein content and sufficient grain rigidity are desired properties for the rice used in high-quality sake brewing such as Daiginjo-shu (polishing ratio of the rice, less than 50%). Two kinds of rice, sake rice (SR) and cooking rice (CR), have been used for sake brewing. Compared with those of SR, analyses of CR for high-quality sake brewing using highly polished rice have been limited. Here we described the original screening of late-maturing CR Sensyuraku (SEN) as rice with low protein content and characterization of its properties for high-quality sake brewing. The protein content of SEN was lower than those of SR Gohyakumangoku (GOM) and CR Yukinosei (YUK), and its grain rigidity was higher than that of GOM. The excellent properties of SEN with respect to both water-adsorption and enzyme digestibility were confirmed using a Rapid Visco Analyzer (RVA). Further, we confirmed a clear taste of sake produced from SEN by sensory evaluation. Thus, SEN has excellent properties, equivalent to those of SR, for high-quality sake brewing.

Boride Formation Induced by pcBN Tool Wear in Friction-Stir-Welded Stainless Steels

NASA Astrophysics Data System (ADS)

Park, Seung Hwan C.; Sato, Yutaka S.; Kokawa, Hiroyuki; Okamoto, Kazutaka; Hirano, Satoshi; Inagaki, Masahisa

2009-03-01

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

Basin-scale contributions of Cr, Ni and Co from Ortegal Complex to the surrounding coastal environment (SW Europe).

PubMed

Prego, Ricardo; Caetano, Miguel; Ospina-Alvarez, Natalia; Raimundo, Joana; Vale, Carlos

2014-01-15

The enrichment of Cr and Ni in the coastal zones is usually associated with anthropogenic sources such as the tanning, galvanization, ceramic, and cement industries. However, geological complexes of specific lithologic composition located near shorelines may act as natural sources of metals to the continental shelf. Cape Ortegal (SW Europe) is an ultramafic complex that has Cr, Ni and Co enriched in rocks due to the minerals chromite, chromospinel, gersdorfite and pentlandite. Thus, the hypothesis that this geological complex contributes to metal enrichment in Ortigueira and Barqueiro Rias and the adjacent continental shelf was tested. Chromium, Ni, and Co were determined in water and in suspended particulate matter of ria tributaries, rainfall, surface sediments, mussels, and algae. High contents of Cr (max. 1670mg·kg(-1)) and Ni (max. 1360 mg · kg(-1)) were found in the sediments surrounding Cape Ortegal and the Ortigueira Ria as a result of erosion of exposed cliffs. Dissolved Cr and Ni concentrations in fluvial waters were significantly higher in the rivers that crosses the Ortegal Complex, i.e. Lourido (0.47 μg Cr · L(-1); 9.4 μg Ni · L(-1)) and Landoi (0.37 μg Cr · L(-1); 4.3 μg Ni · L(-1)), in comparison with the nearby basin out of the complex influence (Sor River: <0.01 μg Cr · L(-1); 0.57 μg Ni · L(-1)). The annual fluvial contributions of Cr and Ni to the Ortigueira Ria were higher than fluxes into the Barqueiro Ria. Moreover, the increase in Cr and Ni in the rainfall in summer demonstrated the importance of the atmosphere pathway for introducing these elements into the aquatic environment. As a consequence, the contents of these metals in soft tissues and shell of mussels and algae from the Ortigueira Ria were higher than the organisms from Barqueiro Ria. Thus, geological complexes, such as the Cape Ortegal, located in an uncontaminated area, can increase the land-sea exchange of trace metals. © 2013.

The High-Temperature Wear and Oxidation Behavior of CrC-Based HVOF Coatings

NASA Astrophysics Data System (ADS)

Houdková, Šárka; Česánek, Zdeněk; Smazalová, Eva; Lukáč, František

2018-01-01

Three commercially available chromium carbide-based powders with different kinds of matrix (Cr3C2-25%NiCr; Cr3C2-25%CoNiCrAlY and Cr3C2-50%NiCrMoNb) were deposited by an HVOF JP-5000 spraying gun, evaluated and compared. The influence of heat treatment on the microstructure and properties, as well as the oxidation resistance in a hot steam environment ( p = 24 MPa; T = 609 °C), was evaluated by SEM and XRD with respect to their potential application in the steam power industry. The sliding wear resistance measured at room and elevated ( T = 600 °C) temperatures according to ASTM G-133. For all three kinds of chromium carbide-based coatings, the precipitation of secondary carbides from the supersaturated matrix was observed during the heat treatment. For Cr3C2-25%NiCr coating annealed in hot steam environment as well as for Cr3C2-25%CoNiCrAlY coating in both environments, the inner carbide oxidation was recorded. The sliding wear resistance was found equal at room temperature, regardless of the matrix composition and content, while at elevated temperatures, the higher wear was measured, varying in dependence on the matrix composition and content. The chromium carbide-based coating with modified matrix composition Cr3C2-50%NiCrMoNb is suitable to replace the Cr3C2-25%NiCr coating in a hot steam environment to eliminate the risk of failure caused by inner carbide oxidation.

Chromium uptake by rice and accumulation in soil amended with municipal solid waste compost.

PubMed

Bhattacharyya, P; Chakraborty, A; Chakrabarti, K; Tripathy, S; Powell, M A

2005-09-01

Effect of addition of municipal solid waste compost (MSWC) on chromium (Cr) content of submerged rice paddies was studied. Experiments were conducted during the three consecutive wet seasons from 1997 to 1999 on rice grown under submergence, at the Experimental Farm of Calcutta University, India. A sequential extraction method was used to determine the various chromium fractions in MSWC and cow dung manure (CDM). Chromium was significantly bound to the organic matter and Fe and Mn oxides in MSWC and CDM. Chromium content in rice straw was higher than in rice grain. Chromium bound with organic matter in MSWC best correlated with straw Cr (r=0.99**) followed by Fe and Mn oxides (r=0.97*) and water soluble as well as exchangeable fractions (r=0.96*). The water soluble and the exchangeable fractions in MSWC best correlated with grain Cr (r=0.98*). The Cr content of rice grain had the highest correlation with water soluble and exchangeable Cr (r=0.99**) while the straw Cr best correlated with the Fe and Mn oxides (r=0.98*). Both the carbonate bound and residual fractions in MSWC and CDM did not significantly correlate with rice straw and grain Cr. MSWC would be a valuable resource for agriculture if it can be used safely, but long-term use may require the cessation of the dumping by the leather tanneries and other major contributors of pollutants.

Speciation studies of nickel and chromium in wastewater from an electroplating plant.

PubMed

Kiptoo, Jackson K; Ngila, J Catherine; Sawula, Gerald M

2004-09-08

A speciation scheme involving the use of flame atomic absorption spectrometry (FAAS) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) techniques was applied to studies of nickel and chromium in wastewater from a nickel-chrome electroplating plant. Dimethylglyoxime (DMG) and diethylenetriaminepentaacetic acid (DTPA) were employed as complexing agents for adsorptive voltammetric determination of Ni and Cr, respectively. Cr(III) and Cr(VI) were determined by exploiting differences in their reactivity towards DTPA at HMDE. Total dissolved metal content was in the range 2906-3141 and 30.7-31.2mgl(-1) for Ni and Cr, respectively. A higher percentage of the metal was present as labile species (mean value of 67.9% for Ni and 79.8% for Cr) suggesting that strongly binding ligands are not ubiquitous in the sample. About 77.8% of Cr was found to exist in the higher oxidization state, Cr(IV). Results on effect of dilution on lability of the metal forms in the sample using DPAdCSV showed slight peak shifts to a more negative (cathodic) value by -0.036V for Ni and -0.180V for Cr with a dilution factor of 100, while peak intensity (cathodic current) remained fairly constant.

Further improvement of mechanical and tribological properties of Cr-doped diamond-like carbon nanocomposite coatings by N codoping

NASA Astrophysics Data System (ADS)

Zou, Changwei; Xie, Wei; Tang, Xiaoshan

2016-11-01

In this study, the effects of nitrogen codoping on the microstructure and mechanical properties of Cr-doped diamond-like carbon (DLC) nanocomposite coatings were investigated in detail. Compared with undoped DLC coatings, the Cr-DLC and N/Cr-DLC coatings showed higher root-mean-square (RMS) roughness values. However, from the X-ray photoelectron spectroscopy (XPS) and Raman results, the fraction of sp2 carbon bonds of N/Cr-DLC coatings increased with increasing N content, which indicated the graphitization of the coatings. The hardness and elastic modulus of N/Cr-DLC coatings with 1.8 at. % N were about 26.8 and 218 GPa, respectively. The observed hardness increase with N codoping was attributed to the incorporation of N in the C network along with the formation of CrC(N) nanoparticles, as confirmed from the transmission electron microscopy (TEM) results. The internal stress markedly decreased from 0.93 to 0.32 GPa as the N content increased from 0 to 10.3 at. %. Furthermore, N doping significantly improved the high-temperature dry friction behavior of DLC coatings. The friction coefficient of N/Cr-DLC coatings with 8.0 and 10.3 at. % N was kept at about 0.2 during the overall sliding test at 500 °C. These results showed that appropriate N doping could promote the mechanical and tribological properties of Cr-DLC nanocomposite coatings.

MOR vs SSZ origin of the Aladaǧ ophiolite (S-Turkey): implications from clinopyroxene geochemistry

NASA Astrophysics Data System (ADS)

Saka, Samet; Uysal, Ibrahim; Seitz, Michael; Melih Akmaz, Recep

2017-04-01

The Aladaǧ ophiolite is located in the eastern Taurides, north of the city of Adana, southern Turkey. From bottom to top it is composed of mantle peridotites, ultramafic-mafic cumulates, isotropic (massive) gabbro and diabase dykes. Mantle peridotites, represented by varying degrees of serpentinized dunite, harzburgite and lherzolite, are divided into two subgroups according to spinel Cr# and Lanthanum Group Element (LGE) contents. Group-1 mantle peridotites contain spinel with low Cr# [100×Cr/(Cr+Al) = 13-47] values and relatively high heavy LGE contents whereas Group-2 mantle peridotites contain spinel with relatively higher Cr# (44-74) values and lower heavy LGE contents. Clinopyroxene in the Aladaǧ mantle peridotites are diopside in composition. Clinopyroxenes from the Group-1 samples have TiO2 contents up to 0.37 wt.% and Na2O contents up to 0.89 wt.%. Conversely, the Group-2 clinopyroxenes were relatively depleted compared to the Group-1 clinopyroxenes in terms of TiO2 (<0,1 wt.%) and Na2O (<0.56 wt.%) contents. The Al2O3 contents are between 0.36-5.75 wt.% for the Group-1 clinopyroxenes and this value is relatively low and range between 0.06-2.68 wt.% for the Group-2 clinopyroxenes. Chondrite-normalized LGE patterns of clinopyroxene in the Group-1 and the Group-2 samples differ from each other. While the Group-1 clinopyroxenes show almost flat HLGE to MLGE patterns (DyN/LuN= 0.35-1.30 avg; 0.75), the Group-2 clinopyroxenes are represented by a more significant depletion from HLGE to MLGE (DyN/LuN= 0.04-0.41 avg; 0.19). Ti and Dy contents of clinopyroxene from the Group-1 samples range between 320-2536 ppm and 0.43-2.4 ppm, respectively. However, the Group-2 clinopyroxenes contain rather lower Ti and Dy contents compared to Group-1 clinopyroxenes, varying from 34 to 289 ppm and 0.02 to 0.20 ppm, respectively. The major oxide composition and LGE patterns as well as Ti and Dy contents of the clinopyroxenes indicate that Group-1 samples are relatively lower-degree partial melting residue left after melting in the mid-ocean ridges, while the Group-2 samples are higher degree partial melting residue at suprasubduction zone. The high Ti versus Dy and Zr contents of Group-1 clinopyroxenes support that they are dry melting residues at mid-ocean ridge setting; however, lower Ti contents for a given Zr contents of Group-2 clinopyroxenes imply that these clinopyroxenes are formed as a result of hydrous partial melting. This study was supported by #114Y094 TUBITAK project

Metal accumulation, growth, antioxidants and oil yield of Brassica juncea L. exposed to different metals.

PubMed

Sinha, Sarita; Sinam, Geetgovind; Mishra, Rohit Kumar; Mallick, Shekhar

2010-09-01

In agricultural fields, heavy metal contamination is responsible for limiting the crop productivity and quality. This study reports that the plants of Brassica juncea L. cv. Pusa bold grown on contaminated substrates [Cu, Cr(VI), As(III), As(V)] under simulated field conditions have shown translocation of metals to the upper part and its sequestration in the leaves without significantly affecting on oil yield, except for Cr and higher concentration of As(V), compared to control. Decrease in the oil content in As(V) treated plants was observed in a dose dependent manner; however, maximum decrease was recorded in Cr treated plants. Among all the metal treatments, Cr was the most toxic as evident from the decrease in oil content, growth parameters and antioxidants. The accumulation of metals was below the detection limit in the seeds grown on 10 and 30 mg kg(-1) As(III) and Cr(VI); 10 mg kg(-1) As(V)) and thus can be recommended only for oil cultivation. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Tissue accumulation and urinary excretion of chromium in rats fed diets containing graded levels of chromium chloride or chromium picolinate.

PubMed

Yoshida, Munehiro; Hatakeyama, Erika; Hosomi, Ryota; Kanda, Seiji; Nishiyama, Toshimasa; Fukunaga, Kenji

2010-08-01

To attempt a risk assessment of the excess intake of trivalent chromium (Cr), tissue Cr accumulation and urinary Cr excretion were examined in weanling rats fed experimental diets containing graded levels of Cr chloride (CrCl3) or Cr picolinate (CrPic). Thirty-six male weanling 4-weeks-old Wistar rats were divided into six groups and fed a casein-based semi-purified diet (Cr content: <0.02 microg/g) supplemented with 1, 10, or 100 microg Cr/g as CrCl3 or CrPic for 28 days. Among the experimental groups, no significant difference was observed in body weight; however, supplementation of 100 microg Cr/g to the diets caused a significant low liver weight irrespective of the chemical species of Cr. Activities of serum aspartate aminotransferase and alanine aminotransferase were significantly elevated in rats given CrPic at 100 microg Cr/g. In the liver, kidney and femur, Cr accumulation increased with elevation of the dietary Cr level. No influence of the difference in the chemical species of supplemented Cr was observed in the liver and kidney, but CrCl3 caused significantly higher Cr accumulation than CrPic in the femur of rats given 100 microg Cr/g. Daily urinary Cr excretion elevated with the increase of the dietary Cr level. Rats given CrPic showed significantly higher daily urinary Cr excretion than those given CrCl3, particularly at a dietary Cr level of 100 microg/g. The rate of urinary Cr excretion in rats given CrPic was constant, irrespective of the dietary Cr level, but that of rats given CrCl3 fell with the increase of the dietary Cr level. These results indicate that the lowest adverse effect level of dietary Cr is less than 100 microg/g, irrespective of the chemical species of Cr.

Phase Evolution and Properties of Al2CrFeNiMo x High-Entropy Alloys Coatings by Laser Cladding

NASA Astrophysics Data System (ADS)

Wu, Wei; Jiang, Li; Jiang, Hui; Pan, Xuemin; Cao, Zhiqiang; Deng, Dewei; Wang, Tongmin; Li, Tingju

2015-10-01

A series of Al2CrFeNiMo x ( x = 0 to 2.0 at.%) high-entropy alloys coatings was synthesized on stainless steel by laser cladding. The effect of Mo content on the microstructures and mechanical properties of Al2CrFeNiMo x coatings was studied. The results show that the laser clad layer consists of the cladding zone, bonding zone, and heat-affected zone. The Al2CrFeNiMo x coatings are composed of two simple body-center cubic phases and the cladding zone is mainly composed of equiaxed grains. When the content of Mo reaches 2 at.%, a eutectic structure is found in the interdendritic regions. The surface microhardness of the Al2CrFeNiMo2 coating is 678 HV, which is about three times higher than that of the substrate (243 HV). Compared with stainless steel, the wear resistance of the coatings has been improved greatly. The wear mass loss of the Al2CrFeNiMo alloy is 9.8 mg, which is much less than that of the substrate (18.9 mg) and its wear scar width is the lowest among the Al2CrFeNiMo x coatings, indicating that the wear resistance of the Al2CrFeNiMo is the best.

Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions.

PubMed

Zheng, Cancai; Huang, Yanling; Xiao, Fang; Lin, Xi; Lloyd, Karen

2016-02-01

An experiment was conducted to investigate the effects of dietary chromium (Cr) source and concentration on growth performance, carcass traits, and some serum lipid parameters of broilers under normal rearing conditions for 42 days. A total of 252 1-day-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involved in a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate (CrPro), Cr picolinate (CrPic), Cr chloride (CrCl3)) and two concentrations of added Cr (0.4 and 2.0 mg of Cr/kg) plus a Cr-unsupplemented control diet. The results showed that dietary Cr supplementation tended to increase the breast muscle percentage compared with the Cr-unsupplemented control group (P = 0.0784), while Cr from CrPic tended to have higher breast muscle percentage compared with Cr from CrCl3 (P = 0.0881). Chromium from CrPic also tended to increase the breast intramuscular fat (IMF) compared with Cr from CrCl3 (P = 0.0648). In addition, supplementation of 0.4 mg/kg Cr tended to decrease low-density lipoprotein cholesterol (LDL-C) (P = 0.0614). Compared with the control group, broilers fed Cr-supplemented diets had higher triglyceride (TG) (P = 0.0129) regardless of Cr source and Cr concentration. Chromium from CrPro and CrPic had lower total cholesterol (TC) compared with Cr from CrCl3 (P = 0.0220). These results indicate that dietary supplementation of Cr has effects on carcass characteristics and serum lipid parameters of broilers under normal rearing conditions, while supplementation of organic Cr can improve carcass characteristics and reduce the cholesterol content in serum.

Quantitative aspects of contact allergy to chromium and exposure to chrome-tanned leather.

PubMed

Hansen, Malene Barré; Rydin, Stefan; Menné, Torkil; Duus Johansen, Jeanne

2002-09-01

The potential of trivalent and hexavalent chromium to induce and elicit allergic contact dermatitis and the degree of chromium exposure from leather products are reviewed. Chromium dermatitis is often due to exposure in the occupational environment, with cement being one of the most common chromium sources. However, consumer products such as chromium(III)-tanned leather products are also an important source of chromium exposure. Apart from Cr(III), which is used for tanning, leather often also contains trace amounts of Cr(VI), which is formed by oxidation of Cr(III) during the tanning process. In a recent study of the Cr(VI) content of leather products bought on the Danish market, 35% of such articles had a Cr(VI) content above the detection limit of 3 p.p.m., ranging from 3.6 p.p.m. to 14.7 p.p.m. Leachable Cr(III) was detected at levels of 430-980 p.p.m. An examination of available dose-response studies showed that exposure to occluded patch test concentrations of 7-45 p.p.m. Cr(VI) elicits a reaction in 10% of the chromium-sensitive patients. When reviewing repeated open exposure studies, it is seen that either exposure to 5 p.p.m. Cr(VI) in the presence of 1% sodium lauryl sulfate (SLS) or exposure to 10 p.p.m. Cr(VI) alone both elicit eczema in chromium-sensitive patients. The eliciting capacity of Cr(III) has not been systematically investigated but, compared to Cr(VI), much higher concentrations are needed to elicit eczema.

Calculation and characteristic analysis on synergistic effect of CF3I gas mixtures

NASA Astrophysics Data System (ADS)

Su, ZHAO; Yunkun, DENG; Yuhao, GAO; Dengming, XIAO

2018-06-01

CF3I is a potential SF6 alternative gas. In order to study the insulation properties and synergistic effects of CF3I/N2 and CF3I/CO2 gas mixtures, two-term approximate Boltzmann equations were used to obtain the ionization coefficient α, attachment coefficient η and the critical equivalent electrical field strength (E/N)cr. The results show that the (E/N)cr of CF3I gas at 300 K is 1.2 times that of SF6 gas, and CF3I/N2 and CF3I/CO2 gas mixtures both have synergistic effect occurred. The synergistic effect coefficient of CF3I/CO2 gas mixture was higher than that of CF3I/N2 gas mixture. But the (E/N)cr of CF3I/N2 is higher than that of CF3I/CO2 under the same conditions. When the content of CF3I exceeds 20%, the (E/N)cr of CF3I/N2 and CF3I/CO2 gas mixture increase linearly with the increasing of CF3I gas content. The breakdown voltage of CF3I/N2 gas mixture is also higher than that of CF3I/CO2 gas mixture in slightly non-uniform electrical field under power frequency voltage, but the synergistic effect coefficients of the two gas mixtures are basically the same.

Incineration of tannery sludge under oxic and anoxic conditions: study of chromium speciation.

PubMed

Kavouras, P; Pantazopoulou, E; Varitis, S; Vourlias, G; Chrissafis, K; Dimitrakopulos, G P; Mitrakas, M; Zouboulis, A I; Karakostas, Th; Xenidis, A

2015-01-01

A tannery sludge, produced from physico-chemical treatment of tannery wastewaters, was incinerated without any pre-treatment process under oxic and anoxic conditions, by controlling the abundance of oxygen. Incineration in oxic conditions was performed at the temperature range from 300°C to 1200°C for duration of 2h, while in anoxic conditions at the temperature range from 400°C to 600°C and varying durations. Incineration under oxic conditions at 500°C resulted in almost total oxidation of Cr(III) to Cr(VI), with CaCrO4 to be the crystalline phase containing Cr(VI). At higher temperatures a part of Cr(VI) was reduced, mainly due to the formation of MgCr2O4. At 1200°C approximately 30% of Cr(VI) was reduced to Cr(III). Incineration under anoxic conditions substantially reduced the extent of oxidation of Cr(III) to Cr(VI). Increase of temperature and duration of incineration lead to increase of Cr(VI) content, while no chromium containing crystalline phase was detected. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural and surface properties of CuO-ZnO-Cr{sub 2}O{sub 3} catalysts and their relationship with selectivity to higher alcohol synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos-Martin, J.M.; Fierro, J.L.G.; Guerrero-Ruiz, A.

1995-10-01

A series of copper-zinc-chromium catalysts of different compositions and calcination temperatures has been prepared, characterized by several techniques (BET specific surface area, XRD, gravimetric TPR, TPD-CO, and XPS), and tested under high alcohol synthesis (HAS) conditions. CO hydrogenation was carried out at reaction temperatures of 523-598 K and 50 bar total pressure. The influence of catalyst composition, calcination temperature, and surface characteristics on the HAS selectivity was studied. The optimum HAS yields were found in the low Cr content region, but chromium was needed. Although chromium oxide does not seem to be involved in the catalytic site, its presence inmore » the catalyst composition is essential, owing to the larger specific surfaces and catalyst stability obtained at the highest reaction temperatures. For low Cr content composition, the temperature-programmed reduction (TPR) profiles were shifted to higher temperatures and simultaneously larger CO{sub 2} amounts were found in the temperature-programmed desorption profiles of adsorbed CO (TPD-CO). Photoelectron spectra (XPS) revealed that the oxidation state of copper is Cu{sup 2+} in the calcined catalysts and Cu{sup O} in the reduced ones; Cu{sup +} was only stabilized in a CuCr{sub 2}O{sub 4} spinel in the Cr-rich catalysts. These features derived from catalyst characterization are discussed in the framework of the catalytic behaviour for HAS synthesis. 53 refs., 7 figs., 4 tabs.« less

The Content of the 14 Metals in Cancellous and Cortical Bone of the Hip Joint Affected by Osteoarthritis

PubMed Central

Zioła-Frankowska, Anetta; Kubaszewski, Łukasz; Dąbrowski, Mikołaj; Kowalski, Artur; Rogala, Piotr; Strzyżewski, Wojciech; Łabędź, Wojciech; Kanicky, Viktor

2015-01-01

The aim of the study was to determine the content of particular elements Ca, Mg, P, Na, K, Zn, Cu, Fe, Mo, Cr, Ni, Ba, Sr, and Pb in the proximal femur bone tissue (cancellous and cortical bone) of 96 patients undergoing total hip replacement for osteoarthritis using ICP-AES and FAAS analytical techniques. The interdependencies among these elements and their correlations depended on factors including age, gender, place of residence, tobacco consumption, alcohol consumption, exposure to environmental pollution, physical activity, and type of degenerative change which were examined by statistical and chemometric methods. The factors that exerted the greatest influence on the elements in the femoral head and neck were tobacco smoking (higher Cr and Ni content in smokers), alcohol consumption (higher concentrations of Ni, Cu in people who consume alcohol), and gender (higher Cu, Zn, and Ni concentrations in men). The factors influencing Pb accumulation in bone tissue were tobacco, alcohol, gender, and age. In primary and secondary osteoarthritis of the hip, the content and interactions of elements are different (mainly those of Fe and Pb). There were no significant differences in the concentrations of elements in the femoral head and neck that could be attributed to residence or physical activity. PMID:26357659

Efficacy of dietary chromium (III) supplementation on tissue chromium deposition in finishing pigs.

PubMed

Wang, Min-Qi; Li, Hui; He, Yu-Dan; Wang, Chao; Tao, Wen-Jing; Du, Yong-Jie

2012-09-01

The study was conducted to evaluate the efficacy of different forms of trivalent chromium (Cr) supplementation on tissue chromium deposition in finishing pigs. A total of 96 pigs with an initial average body mass 65.57±1.05 kg were blocked by body mass and randomly assigned to four treatments with three replicates. Pigs were offered one of four diets including a control diet or the control diet supplemented with 200 μg/kg chromium from either chromium chloride (CrCl(3)), chromium picolinate (CrPic) or chromium nanocomposite (CrNano) for 40 days. During the trial, all pigs were given free access to feed and water. After feeding trial, eight pigs from each treatment were slaughtered for samples collection. The results showed that supplemental CrNano increased Cr content in blood, longissimus muscle, heart, liver, kidney, jejunum, and ileum (P<0.05). Supplemental Cr from three sources increased Cr excretion from all feces (P<0.05). Urinary Cr excretion was increased by CrNano or CrPic supplementation significantly. These results suggested that chromium nanocomposite exhibited more effective on tissue Cr deposition in pigs, which indicated higher absorption compared with CrCl(3) and CrPic.

Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

NASA Astrophysics Data System (ADS)

Viswanathan, S.; Mohan, L.; Bera, Parthasarathi; Kumar, V. Praveen; Barshilia, Harish C.; Anandan, C.

2017-08-01

A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D / I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/ sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type.

PubMed

Keane, Michael; Stone, Samuel; Chen, Bean; Slaven, James; Schwegler-Berry, Diane; Antonini, James

2009-02-01

Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr(VI) concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr(VI) content. The gases used were 95% Ar/5% O(2), 98% Ar/2% O(2), 95% Ar/5%CO(2), and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O(2), Ar/CO(2)), short-circuit (SC) mode (Ar/CO(2) low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O(2)). Results indicate large differences in Cr(VI) in the fumes, with Ar/O(2) (Pulsed)>Ar/O(2)>Ar/CO(2)>Ar/CO(2) (SC)>He/Ar; values were 3000+/-300, 2800+/-85, 2600+/-120, 1400+/-190, and 320+/-290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr(VI) generation were 1.5, 3.2, 4.4, 1.3, and 0.46 microg/min; generation rates were also calculated in terms of microg Cr(VI) per metre of wire used. The generation rates of Cr(VI) increased with increasing O(3) concentrations. Particle size measurements indicated similar distributions, but somewhat higher >0.6 microm fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>or=0.6 microm) and a fine (<0.6 microm) fraction; analysis indicated that Cr(VI) is primarily associated with particles <0.6 microm. The conclusion of the study is that Cr(VI) concentrations vary significantly with welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr(VI) exposures in workplaces by selecting low Cr(VI)-generating processes. Short-circuit processes generated less Cr(VI) than axial-spray methods, and inert gas shielding gave lower Cr(VI) content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O(2) process were both identified as having substantially lower Cr(VI) generation rates per unit of wire used relative to the other processes studied.

Removal of chromium by some multipurpose tree seedlings of Indian thar desert.

PubMed

Mathur, Nishi; Singh, Joginder; Bohra, Sachendra; Bohra, Avinash; Vyas, Anil

2010-01-01

An experiment was conducted to study the potential of chromium (Cr) phytoaccumulatory capabilities of four tree species viz., Anogeissus latifolia, Terminalia arjuna, Tecomella undulata, and Salvadora persica Possibility of enhancement of Cr uptake by citric acid and vesicular arbuscular mycorrhizal fungi (VAM) amendments were also tried. Cr is a major pollutant of the environment. Chromium can exist in oxidation states from III to VI, but the most stable and common forms of Cr are trivalent and hexavalent species. Cr(VI) was more toxic to the tree growth in terms of collar diameter (CD) increment in all the tree species than Cr(lll). Roots accumulated more Cr than shoots in all the tree species. There was more than 10 fold increase in root Cr content in comparison with shoot Cr content in all the trees at all the concentration of Cr and all sources of Cr. Citric acid significantly increased the Cr content in the tissues of roots in all the species under both speciation of Cr. The highest increase in Cr content brought by 20 mM citric acid addition was in A. latifolia Results suggest that Anogeissus latifolia is a potential Cr accumulator with citric acid as soil amendment.

Microelements in solonchaks of the western Trans-Baikal region

NASA Astrophysics Data System (ADS)

Sosorova, S. B.; Merkusheva, M. G.; Boloneva, L. N.; Baldanova, A. L.; Ubugunov, L. L.

2016-04-01

Distribution patterns of microelements (Mn, Zn, Ni, Cu, Cr, Co, Pb, and Cd) in solonchaks of the western Trans-Baikal region were studied. It was found that their concentrations in typical solonchaks of haloxerophytic steppe differed from those in solonchaks of moistened habitats (playa, gleyed, and dark solonchaks) because of the differences in their landscape positions and ecological conditions. A general rise in the contents of the microelements was observed from the northeast to the southwest in agreement with changes in the parent materials. Different degrees of correlation of the contents of the microelements and their exchangeable forms with the contents of soluble salts, humus, and physical clay in the soils and the soil reaction were found. The average and extreme concentrations of the microelements were determined. The studied typical solonchaks differed from the zonal chestnut soils in the higher contents of Co, Cr, and Cd; whereas solonchaks of moistened habitats were enriched in Mn, Co, and Cd.

Intergranular Corrosion Behavior of Low-Nickel and 304 Austenitic Stainless Steels

NASA Astrophysics Data System (ADS)

Bansod, Ankur V.; Patil, Awanikumar P.; Moon, Abhijeet P.; Khobragade, Nilay N.

2016-09-01

Intergranular corrosion (IGC) susceptibility for Cr-Mn austenitic stainless steel and 304 austenitic stainless steel (ASS) was estimated using electrochemical techniques. Optical and SEM microscopy studies were carried out to investigate the nature of IGC at 700 °C with increasing time (15, 30, 60, 180, 360, 720, 1440 min) according to ASTM standard 262 A. Quantitative analysis was performed to estimate the degree of sensitization (DOS) using double loop electrochemical potentiokinetic reactivation (DLEPR) and EIS technique. DLEPR results indicated that with the increase in thermal aging duration, DOS becomes more severe for both types of stainless steel. The DOS for Cr-Mn ASS was found to be higher (65.12% for 1440 min) than that of the AISI 304 ASS (23% for 1440 min). The higher degree of sensitization resulted in lowering of electrical charge capacitance resistance. Chronoamperometry studies were carried out at a passive potential of 0.4 V versus SCE and was observed to have a higher anodic dissolution of the passive film of Cr-Mn ASS. EDS studies show the formation of chromium carbide precipitates in the vicinity of the grain boundary. The higher Mn content was also observed for Cr-Mn ASS at the grain boundary.

Evaluation of Ni-Cr-base alloys for SOFC interconnect applications

NASA Astrophysics Data System (ADS)

Yang, Zhenguo; Xia, Guan-Guang; Stevenson, Jeffry W.

To further understand the suitability of Ni-Cr-base alloys for solid oxide fuel cell (SOFC) interconnect applications, three commercial Ni-Cr-base alloys, Haynes 230, Hastelloy S and Haynes 242 were selected and evaluated for oxidation behavior under different exposure conditions, scale conductivity and thermal expansion. Haynes 230 and Hastelloy S, which have a relatively high Cr content, formed a thin scale mainly comprised of Cr 2O 3 and (Mn,Cr,Ni) 3O 4 spinels under SOFC operating conditions, demonstrating excellent oxidation resistance and a high scale electrical conductivity. In contrast, a thick double-layer scale with a NiO outer layer above a chromia-rich substrate was grown on Haynes 242 in moist air or at the air side of dual exposure samples, indicating limited oxidation resistance for the interconnect application. With a face-centered-cubic (FCC) substrate, all three alloys possess a coefficient of thermal expansion (CTE) that is higher than that of candidate ferritic stainless steels, e.g. Crofer22 APU. Among the three alloys, Haynes 242, which is heavily alloyed with W and Mo and contains a low Cr content, demonstrated the lowest average CTE at 13.1 × 10 -6 K -1 from room temperature to 800 °C, but it was also observed that the CTE behavior of Haynes 242 was very non-linear.

Enhanced photoelectrochemical and optical performance of ZnO films tuned by Cr doping

NASA Astrophysics Data System (ADS)

Salem, M.; Akir, S.; Massoudi, I.; Litaiem, Y.; Gaidi, M.; Khirouni, K.

2017-04-01

In this paper, pure and Cr-doped nanostructured Zinc oxide thin films were synthesized by simple and low cost co-precipitation and spin-coating method with Cr concentration varying between 0.5 and 5 at.%. Crystalline structure of the prepared films was investigated by X-ray diffraction (XRD) and Raman spectroscopy techniques. XRD analysis indicated that the films were indexed as the hexagonal phase of wurtzite-type structure and demonstrated a decrease in the crystallite size with increasing Cr doping content. Cr doping revealed a significant effect on the optical measurements such as transmission and photoluminescence properties. The optical measurements indicated that Cr doping decreases the optical band gap and it has been shifted from 3.41 eV for pure ZnO film to 3.31 eV for 5 at.% Cr-doped one. The photoelectrochemical (PEC) sensing characteristics of Cr-doped ZnO layers were investigated. Amongst all photo-anodes with different Cr dopant concentration, the 2 at.% Cr incorporated ZnO films exhibited fast response and higher photoconduction sensitivity.

The BCC/B2 morphologies in Al xNiCoFeCr high-entropy alloys

DOE PAGES

Ma, Yue; Jiang, Beibei; Li, Chunling; ...

2017-02-15

Here, the present work primarily investigates the morphological evolution of the body-centered-cubic (BCC)/B2 phases in Al xNiCoFeCr high-entropy alloys (HEAs) with increasing Al content. It is found that the BCC/B2 coherent morphology is closely related to the lattice misfit between these two phases, which is sensitive to Al. There are two types of microscopic BCC/B2 morphologies in this HEA series: one is the weave-like morphology induced by the spinodal decomposition, and the other is the microstructure of a spherical disordered BCC precipitation on the ordered B2 matrix that appears in HEAs with a much higher Al content. The mechanical properties,more » including the compressive yielding strength and microhardness of the Al xNiCoFeCr HEAs, are also discussed in light of the concept of the valence electron concentration (VEC).« less

Phyto-management of chromium contaminated soils through sunflower under exogenously applied 5-aminolevulinic acid.

PubMed

Farid, Mujahid; Ali, Shafaqat; Rizwan, Muhammad; Ali, Qasim; Saeed, Rashid; Nasir, Tauqir; Abbasi, Ghulam Hasan; Rehmani, Muhammad Ishaq Asif; Ata-Ul-Karim, Syed Tahir; Bukhari, Syed Asad Hussain; Ahmad, Tanvir

2018-04-30

Soil contamination with heavy metals is threatening the food security around the globe. Chromium (Cr) contamination results in poor quality and reduction in yield of crops. The present research was performed to figure out the Cr toxicity in sunflower and the ameliorative role of 5-aminolevulinic acid (ALA) as a plant growth regulator. The sunflower (FH-614) was grown under increasing concentration of Cr (0, 5, 10 and 20mgkg -1 ) alone and/or in combination with 5-ALA (0, 10 and 20mgL -1 ). Results showed that Cr suppressed the overall growth, biomass, gas exchange attributes and chlorophyll content of sunflower plants. Moreover, lower levels of Cr (5 and 10mgkg -1 ) increased the production of reactive oxygen species (ROS) and electrolyte leakage (EL) along with the activities of antioxidant enzymes i.e., superoxide dismutase (SOD), guaiacole peroxidase (POD), ascorbate (APX), catalase (CAT). But at higher concentration of Cr (20mgkg -1 ), the activities of these enzymes presented a declining trend. However, the addition of 5-ALA significantly alleviated the Cr-induced toxicity in sunflower plant and enhanced the plant growth and biomass parameters along with increased chlorophyll content, gas exchange attributes, soluble proteins and soil plant analysis development (SPAD) values by scavenging the ROS and lowering down the EL. The 5-ALA also enhanced the activities of antioxidant enzymes at all levels of Cr. The increase in Cr concentration in all plant parts such as leaf, root and stem was directly proportional to the Cr concentration in soil. The application of 5-ALA further enhanced the uptake of Cr and its concentration in the plants. To understand this variation in response of plants to 5-ALA, detailed studies are required on plant biochemistry and genetic modifications. Copyright © 2018 Elsevier Inc. All rights reserved.

Fate of chromium in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokisch, J.; Gyori, Z.; Kovacs, B.

The chromium cycle in soil was studied with speciation of chromium. The aim was to look for the possibilities the mobilization of chromium(III) and to measure the rate of chromate reduction in nature and pot and field experiments in Hungarian soils. The authors developed a sensitive and simple method for chromium speciation with a microcolumn connected an inductively coupled plasma atomic emission spectrometer. Detection limits are convenient to measure chromium forms in a 0.01 M CaCl{sub 2} extract of a contaminated soil, but it is not enough to measure that of the uncontaminated soils. CR(VI) as chromate anion is notmore » adsorbed on pH dependent temporary charges of clays but in strongly acidic soil. Therefore CR(VI) can be leached out easily from the top layer of soil and can be transported into the ground water. Chromate ion can be reduced to CR(III) by organic matter of soil in acidic medium. CR(VI) is more stable at higher pH and lower humus content. Thus the reduction much quicker in the upper, weakly acidic top layer. CR(VI) oxidizes the organic matter of soil. The rate of this reaction depends on pH values, the humus content of the soil and temperature. CR(III) leaching in different uncontaminated soils was studied too. There are 3 pathways of mobilization of Cr(III). When pH decreases in soil the CR(III) becomes more soluble, similarly to the aluminium(III) ion. When the soil contains large quantity of water soluble organic ligands, Cr makes complexes with them and complexes formed can be leached out from the top layer. The third possibility is the oxidation of CR(III) to Cr(VI). It could happen on surface of manganese dioxide in the well-aired top layer.« less

A content analysis of Clinical and Translational Science Award (CTSA) strategies for communicating about clinical research participation online.

PubMed

Flood-Grady, Elizabeth; Paige, Samantha R; Karimipour, Nicki; Harris, Paul A; Cottler, Linda B; Krieger, Janice L

2017-12-01

There is a dearth of literature providing guidance on how to effectively communicate about clinical research (CR). Using the transactional model of communication, a content analysis of the investigator (n=62) and participant (n=18) Web sites of institutions funded through the National Institutes of Health Clinical and Translational Science Award (CTSA) was conducted to identify their strategies (e.g., messages) for communicating about CR participation. CTSAs targeted investigators with CR participation content across the main Web sites, although most CTSAs (n=55; 88.7%) also included CR participation content for participants. In total, 18 CTSAs (29%) hosted participant Web sites. Participant sites included 13 message types about CR participation (e.g., registry enrollment) and 5 additional channels (e.g., email, phone number) to communicate about CR. However, many CTSA participant Web sites excluded information explaining the CR process and offered CR content exclusively in English. CTSAs should identify their target audience and design strategies (e.g., messages, channels) accordingly.

Role of Y in the oxidation resistance of CrAlYN coatings

NASA Astrophysics Data System (ADS)

Domínguez-Meister, S.; El Mrabet, S.; Escobar-Galindo, R.; Mariscal, A.; Jiménez de Haro, M. C.; Justo, A.; Brizuela, M.; Rojas, T. C.; Sánchez-López, J. C.

2015-10-01

CrAlYN coatings with different aluminum (4-12 at.%) and yttrium (2-5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr2N, and a more effective Fe and C blocking.

Apollo 15 green glasses.

NASA Technical Reports Server (NTRS)

Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.

1973-01-01

The samples analyzed include 28 spheres, portions of spheres, and angular fragments from soil 15101. Emerald green glasses from other soils are identical to those from 15101. The composition of the green glass is unlike that of any other major lunar glass group. The Fe content is comparable to that in mare basalts, but Ti is much lower. The Mg content is much higher than in most lunar materials analyzed to date, and the Cr content is also high. The low Al content is comparable to that of mare basalt glasses.

Enhanced abiotic reduction of Cr(VI) in a soil slurry system by natural biomaterial addition.

PubMed

Park, Donghee; Ahn, Chi Kyu; Kim, Young Mi; Yun, Yeoung-Sang; Park, Jong Moon

2008-12-30

Among various plant-based natural biomaterials, pine bark was chosen as an efficient biomaterial capable of removing toxic Cr(VI) from aqueous solution. XPS spectra indicated that Cr(VI) was abiotically reduced to Cr(III) in both liquid and solid phases. The Cr(VI)-reducing capacity of pine bark was determined as 545 (+/-1.3)mg-Cr(VI)g(-1) of it, which was 8.7 times higher than that of a common chemical Cr(VI)-reductant, FeSO4 x 7H2O. Because pine bark could completely reduce toxic Cr(VI) to less toxic or nontoxic Cr(III) even at neutral pH, it was used as an organic reductant to remediate Cr(VI)-contaminated soil in this study. Soil slurry system using a bottle roller was applied to ex situ slurry-phase remediation experiments. In the soil slurry system, pine bark completely reduced Cr(VI) to Cr(III) and adsorbed the reduced-Cr(III) on its surface. Abiotic remediation rate of Cr(VI)-contaminated soil increased with the increase of pine bark dosage and with the decreases of Cr(VI) and water contents. In conclusion, pine bark can be used to remediate Cr(VI)-contaminated soil efficiently and environmentally friendly.

Microstructural and Electrochemical Evaluation of Fusion Welded Low-Nickel and 304 SS at Different Heat Input

NASA Astrophysics Data System (ADS)

Bansod, Ankur V.; Patil, Awanikumar P.; Moon, Abhijeet P.; Shukla, Sourabh

2017-12-01

The present research study investigates the effect of heat input using E 308 electrode (controlled by welding current, i.e., 70, 85 and 100 A) on microstructure, mechanical properties and corrosion behavior of low-nickel and 304 stainless steel (SS) weldments produced by shielded metal arc welding technique. SEM investigation shows that with the higher heat input, δ-ferrite content was reduced. Dendrite and inter-dendritic length is also reduced by lowering the heat input. For all the heat inputs, it is observed that δ-ferrite content was higher in 304 stainless steel (SS) as compared to that of low-nickel austenitic stainless steel (Cr-Mn SS). Considering the heat input for Cr-Mn SS, coarse grains were observed in the heat-affected zone region. For low heat input (LHI), tensile fracture surface has exhibited river-like pattern with dimple appearance. Corrosion studies show better pitting resistance for low heat input (LHI) samples due to higher δ-ferrite present in the weld region. Similarly, higher interphase corrosion resistance is observed in both the SS grades causing more dissolution in the LHI samples.

[Determination of 22 inorganic elements in different parts of Lantana camara by ICP-OES].

PubMed

Zhou, Wei-ming; Wang, Ru-yi; Chen, Liu-sheng; Huang, Chuan-bin

2014-09-01

To determine the contents of 22 inorganic elements in different parts of Lantana camara by inductively coupled plasma optical emission spectroscopy (ICP-OES). HNO3-H2 02 digested system was used to completely decomposed the organic compounds effectually by microwave digestion. 22 inorganic elements such as K, Ca, Mg, Fe, Al, Na, Zn, Mn and Cr were determined by ICP-OES under set up working conditions. The contents of K, Ca and Mg were the most in different parts of Lantana camrnara; The contents of K, Ca, Mg, Mn, Sr and Cu in the leaves of Lantana camara were more than that in the root and the branch. The contents of Fe and Na in the root of Lantana camara were more than that in the leaves and the branch. The contents of Pb and Cd were higher than the national standard and Cr had high content in different parts of Lantana camara. The determination method is quick, easy and accurate with high sensitivity,which can determine the contents of 22 inorganic elements accurately in different parts of Lantana camara.

Bioaccumulation of heavy metals in crop plants grown near Almeda Textile Factory, Adwa, Ethiopia.

PubMed

Gitet, Hintsa; Hilawie, Masho; Muuz, Mehari; Weldegebriel, Yirgaalem; Gebremichael, Dawit; Gebremedhin, Desta

2016-09-01

The contents of heavy metals cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) present in water (wastewater and wetland), soils, and food crops collected from the vicinity of Almeda Textile Factory were quantified using Flame Atomic Absorption Spectrometer (FAAS) in order to assess the environmental impact of the textile factory. The contents of heavy metals determined in the wastewater were found below the recommended limit set by WHO and United States Environmental Protection Agency (US EPA) except for Cr, which was found slightly higher than WHO permissible limit. Besides, the contents of the heavy metals determined in soils were below the permissible level of FAO/WHO and Canada maximum allowable limits. Moreover, only the concentrations of Cd and Pb were found above the permissible level set by FAO/WHO in the crop plants studied. Generally, the mean concentrations of heavy metals in the plants were in the decreasing order of: Mn > Zn > Cu > Pb > Ni > Co > Cr > Cd. Nevertheless, higher bioconcentration factor (BCF) was found for Cd (0.108-1.156) followed by Zn (0.081-0.499). In conclusion, comparison of heavy metal concentrations with the permissible limits in all collected sample types i.e. water, soil, and crop plants did not show significant pollution from the factory.

Effects of MC-Type Carbide Forming and Graphitizing Elements on Thermal Fatigue Behavior of Indefinite Chilled Cast Iron Rolls

NASA Astrophysics Data System (ADS)

Ahiale, Godwin Kwame; Choi, Won-Doo; Suh, Yongchan; Lee, Young-Kook; Oh, Yong-Jun

2015-11-01

The thermal fatigue behavior of indefinite chilled cast iron rolls with various V+Nb contents and Si/Cr ratios was evaluated. Increasing the ratio of Si/Cr prolonged the life of the rolls by reducing brittle cementites. Higher V+Nb addition also increased the life through the formation of carbides that refined and toughened the martensite matrix and reduced the thermal expansion mismatch in the microstructure.

Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems

PubMed Central

Bu, Rongyan; Lu, Jianwei; Ren, Tao; Liu, Bo; Li, Xiaokun; Cong, Rihuan

2015-01-01

Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils. PMID:26647157

Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

PubMed

Bu, Rongyan; Lu, Jianwei; Ren, Tao; Liu, Bo; Li, Xiaokun; Cong, Rihuan

2015-01-01

Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

Distribution of heavy metals and hydrocarbon contents in an alfisol contaminated with waste-lubricating oil amended with organic wastes.

PubMed

Adesodun, J K; Mbagwu, J S C

2008-05-01

Contamination of soil and groundwater with mineral oil-based products is among the most common sources of pollution in Nigeria. This study evaluated the distribution of some heavy metals and hydrocarbon content in soil contaminated with waste-lubricating oil (spent oil), and the effectiveness of some abundantly available organic wastes from animal source as remediation alternative to the expensive chemical and physical methods. The main-plot treatments include control (C), cow dung (CD), poultry manure (PM) and pig waste (PW) applied at 10Mg/ha each; while the sub-plot treatments were control (0%), 0.5%, 2.5% and 5% spent oil (SP) applied at 10, 50 and 100 Mg/ha, respectively arranged in a split-plot in Randomized Complete Block Design (RCBD) with four replications. These treatments were applied once each year for two consecutive years. Soil samples (0-20 cm) were collected at 3, 6 and 12 months each year and analyzed for Cr, Ni, Pb and Zn, while the residual total hydrocarbon content (THC) was determined at the end of the 2 years study. Results show significant (p<0.05) accumulation of these metals with spent oil pollution following the sequence 5%SP>2.5%SP>0.5%SP, indicating higher metal pollution with increase in oil pollution. General distribution of Cr, Ni, Pb and Zn, relative to sampling periods, followed 3 months>6 months>12 months in the 1st year indicating reduction in metal levels with time. The trend for 2nd year indicated higher accumulation of Cr and Ni in 12 months, while Pb and Zn decreased with time of sampling. The results further showed higher accumulation of Cr followed by Zn, relative to other metals, with oil pollution. However, addition of organic wastes to the oil polluted soils significantly (p<0.05) led to reduction in the levels of the metals and THC following the order PM>PW>CD.

Compositional and structural properties of pulsed laser-deposited ZnS:Cr films

NASA Astrophysics Data System (ADS)

Nematollahi, Mohammadreza; Yang, Xiaodong; Seim, Eivind; Vullum, Per Erik; Holmestad, Randi; Gibson, Ursula J.; Reenaas, Turid W.

2016-02-01

We present the properties of Cr-doped zinc sulfide (ZnS:Cr) films deposited on Si(100) by pulsed laser deposition. The films are studied for solar cell applications, and to obtain a high absorption, a high Cr content (2.0-5.0 at.%) is used. It is determined by energy-dispersive X-ray spectroscopy that Cr is relatively uniformly distributed, and that local Cr increases correspond to Zn decreases. The results indicate that most Cr atoms substitute Zn sites. Consistently, electron energy loss and X-ray photoelectron spectroscopy showed that the films contain mainly Cr2+ ions. Structural analysis showed that the films are polycrystalline and textured. The films with ~4 % Cr are mainly grown along the hexagonal [001] direction in wurtzite phase. The average lateral grain size decreases with increasing Cr content, and at a given Cr content, increases with increasing growth temperature.

Atomistic simulation of the influence of Cr on the mobility of the edge dislocation in Fe(Cr) alloys

NASA Astrophysics Data System (ADS)

Hafez Haghighat, S. M.; Terentyev, D.; Schäublin, R.

2011-10-01

In this work Fe-Cr compounds, as model alloys for the ferritic base steels that are considered as main candidates for the structural materials of the future fusion reactors, are studied using molecular dynamics simulations. The Cr or so-called α' precipitates, which are obstacles to dislocations, affect mechanical properties, leading to hardening and loss of ductility. The flow stress to move an edge dislocation in a Cr solid solution in pure Fe is studied as a function of Cr content. The strength of a nanometric Cr precipitate as obstacle to an edge dislocation in pure Fe is investigated as a function of its Cr content. Results show that with increasing Cr content the precipitate obstacle strength increases, with a strong sensitivity to the local atomic order. Temperature induces a monotonic decrease of the flow stress of the Cr solid solution and of the Cr precipitate obstacle strength.

Continuous direct compression as manufacturing platform for sustained release tablets.

PubMed

Van Snick, B; Holman, J; Cunningham, C; Kumar, A; Vercruysse, J; De Beer, T; Remon, J P; Vervaet, C

2017-03-15

This study presents a framework for process and product development on a continuous direct compression manufacturing platform. A challenging sustained release formulation with high content of a poorly flowing low density drug was selected. Two HPMC grades were evaluated as matrix former: standard Methocel CR and directly compressible Methocel DC2. The feeding behavior of each formulation component was investigated by deriving feed factor profiles. The maximum feed factor was used to estimate the drive command and depended strongly upon the density of the material. Furthermore, the shape of the feed factor profile allowed definition of a customized refill regime for each material. Inline NIRs was used to estimate the residence time distribution (RTD) in the mixer and monitor blend uniformity. Tablet content and weight variability were determined as additional measures of mixing performance. For Methocel CR, the best axial mixing (i.e. feeder fluctuation dampening) was achieved when an impeller with high number of radial mixing blades operated at low speed. However, the variability in tablet weight and content uniformity deteriorated under this condition. One can therefore conclude that balancing axial mixing with tablet quality is critical for Methocel CR. However, reformulating with the direct compressible Methocel DC2 as matrix former improved tablet quality vastly. Furthermore, both process and product were significantly more robust to changes in process and design variables. This observation underpins the importance of flowability during continuous blending and die-filling. At the compaction stage, blends with Methocel CR showed better tabletability driven by a higher compressibility as the smaller CR particles have a higher bonding area. However, tablets of similar strength were achieved using Methocel DC2 by targeting equal porosity. Compaction pressure impacted tablet properties and dissolution. Hence controlling thickness during continuous manufacturing of sustained release tablets was crucial to ensure reproducible dissolution. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental radiation and potential ecological risk levels in the intertidal zone of southern region of Tamil Nadu coast (HBRAs), India.

PubMed

Punniyakotti, J; Ponnusamy, V

2018-02-01

Natural radioactivity content and heavy metal concentration in the intertidal zone sand samples from the southern region of Tamil Nadu coast, India, have been analyzed using gamma ray spectrometer and ICP-OES, respectively. From gamma spectral analysis, the average radioactivity contents of 238 U, 232 Th, and 40 K in the intertidal zone sand samples are 12.13±4.21, 59.03±4.26, and 197.03±26.24Bq/kg, respectively. The average radioactivity content of 232 Th alone is higher than the world average value. From the heavy metal analysis, the average Cd, Cr, Cu, Ni, Pb, and Zn concentrations are 3.1, 80.24, 82.84, 23.66, 91.67, and 137.07ppm, respectively. The average Cr and Ni concentrations are lower, whereas other four metal (Cd, Cu, Pb, and Zn) concentrations are higher than world surface rock average values. From pollution assessment parameter values, the pollution level is "uncontaminated to moderately contaminated" in the study area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Heavy metals in fish tissues/stomach contents in four marine wild commercially valuable fish species from the western continental shelf of South China Sea.

PubMed

Gu, Yang-Guang; Lin, Qin; Huang, Hong-Hui; Wang, Liang-Gen; Ning, Jia-Jia; Du, Fei-Yan

2017-01-30

The concentrations of heavy metals (Cd, Pb, Cr, Ni, Cu and Zn) were determined in four commercially valuable fish species (Thunnus obesus, Decapterus lajang, Cubiceps squamiceps and Priacanthus macracanthus), collected in the western continental shelf of the South China Sea. Concentrations of Cd, Pb, Cr, Ni, Cu, and Zn in fish muscles were 0.006-0.050, 0.13-0.68, 0.18-0.85, 0.11-0.25, 0.12-0.77, and 2.41-4.73μg/g, wet weight, respectively. Concentrations of heavy metals in all species were below their acceptable daily upper limit, suggesting human consumption of these wild fish species may be safe, with health risk assessment based on the target hazard quotients (THQ) and total THQ, indicating no significant adverse health effects with consumption. The average concentrations of Zn were higher in gills than in stomach contents, backbones or muscle, while conversely, the other heavy metals had higher concentrations in stomach contents than in other tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

Granulometric selectivity in Liza ramado and potential contamination resulting from heavy metal load in feeding areas

NASA Astrophysics Data System (ADS)

Pedro, Sílvia; Canastreiro, Vera; Caçador, Isabel; Pereira, Eduarda; Duarte, Armando C.; Raposo de Almeida, Pedro

2008-11-01

The stomach contents of thin-lipped grey mullets Liza ramado were analysed in terms of granulometric composition and compared to the sediment of potential feeding areas in the Tagus estuary. Total organic matter (TOM) content and heavy metal content were determined in the surface sediment of three areas and eight trace elements were quantified: Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. The three sampled areas did not differ in TOM; and the heavy metal content was below Effects Range-Low level for most elements. The mean observed concentrations were present in the following sequence: Zn > Pb > Cr > Cu ≈ Ni > Co > Cd > Hg. Stomach contents granulometric composition provided information about the feeding selectivity of the mullets. Sediment fractions with particle size between 20 and 50 μm are preferred, independently of the fishes' length. Smaller standard length (SL) fishes have a higher positive selection of fine grained sediments than those with a larger SL. Finer fractions usually have higher concentration of heavy metals, which makes younger specimens of the thin-lipped grey mullet potentially more exposed to heavy metal load in the estuary. Metal concentration was not independent from the sampling point, presenting higher values near the margins and the estuary tidal drainage system. This means that during the first period of each tidal cycle, the mullets will feed first on the most contaminated areas, as a consequence of their movement following the rising tide to feed on previously exposed areas.

Phylloquinone and Menaquinone-4 Tissue Distribution at Different Life Stages in Male and Female Sprague-Dawley Rats Fed Different VK Levels Since Weaning or Subjected to a 40% Calorie Restriction since Adulthood.

PubMed

Ferland, Guylaine; Doucet, Isabelle; Mainville, Dominique

2016-03-04

Whether through the vitamin K-dependent proteins or the individual K vitamers, vitamin K (VK) is associated with a number of age-related conditions (e.g., osteoporosis, atherosclerosis, insulin resistance, cognitive decline). In light of this, we investigated the influence of lifetime dietary VK exposure on the tissue distribution of phylloquinone (K₁) and menaquinone-4 (MK-4) vitamers in 3-, 12- and 22-month-old male and female rats fed different K₁ diets since weaning or subjected to a 40% calorie restricted diet (CR) since adulthood. Dietary K₁ intakes around the minimal amount required for normal blood coagulation had no significant influence on body weights of both male and female rats at different life stages. Tissue contents of the K vitamers differed according to organs, were generally higher in females than in males, and increased with K₁ intake. The MK-4/total VK ratios tended to be increased in old age possibly reflecting an increased physiological demand for MK-4 during aging. Our study also confirmed the greater susceptibility of male rats to low VK containing diet, notably at a younger age. Despite lifelong higher K₁ intakes per unit body weight, tissue K₁ and MK-4 contents at 20 months were generally lower in CR rats compared to their ad libitum (AL) counterparts. Whether the lower tissue MK-4 content is the result of lower synthesis from K₁ or greater tissue utilization remains to be determined. However, the more youthful coagulation profile observed in old CR rats (vs. AL rats) tends to support the notion that CR is associated with greater utilization of the K vitamers to sustain physiological functions.

Phylloquinone and Menaquinone-4 Tissue Distribution at Different Life Stages in Male and Female Sprague–Dawley Rats Fed Different VK Levels Since Weaning or Subjected to a 40% Calorie Restriction since Adulthood

PubMed Central

Ferland, Guylaine; Doucet, Isabelle; Mainville, Dominique

2016-01-01

Whether through the vitamin K-dependent proteins or the individual K vitamers, vitamin K (VK) is associated with a number of age-related conditions (e.g., osteoporosis, atherosclerosis, insulin resistance, cognitive decline). In light of this, we investigated the influence of lifetime dietary VK exposure on the tissue distribution of phylloquinone (K1) and menaquinone-4 (MK-4) vitamers in 3-, 12- and 22-month-old male and female rats fed different K1 diets since weaning or subjected to a 40% calorie restricted diet (CR) since adulthood. Dietary K1 intakes around the minimal amount required for normal blood coagulation had no significant influence on body weights of both male and female rats at different life stages. Tissue contents of the K vitamers differed according to organs, were generally higher in females than in males, and increased with K1 intake. The MK-4/total VK ratios tended to be increased in old age possibly reflecting an increased physiological demand for MK-4 during aging. Our study also confirmed the greater susceptibility of male rats to low VK containing diet, notably at a younger age. Despite lifelong higher K1 intakes per unit body weight, tissue K1 and MK-4 contents at 20 months were generally lower in CR rats compared to their ad libitum (AL) counterparts. Whether the lower tissue MK-4 content is the result of lower synthesis from K1 or greater tissue utilization remains to be determined. However, the more youthful coagulation profile observed in old CR rats (vs. AL rats) tends to support the notion that CR is associated with greater utilization of the K vitamers to sustain physiological functions. PMID:26959054

From solid solution to cluster formation of Fe and Cr in α-Zr

NASA Astrophysics Data System (ADS)

Burr, P. A.; Wenman, M. R.; Gault, B.; Moody, M. P.; Ivermark, M.; Rushton, M. J. D.; Preuss, M.; Edwards, L.; Grimes, R. W.

2015-12-01

To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques - atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

[Comparison of Coptidis Rhizoma processed with different ginger juice based on metabolomics].

PubMed

Zhong, Ling-Yun; Su, Dan; Zhu, Jing; Deng, Yu-Fen

2016-07-01

To investigate the effects of two different ginger juices on the medicinal properties of Coptidis Rhizoma(CR) by using UPLC-MS-TOF. The rats were fed with decoction of raw CR (RCR), CR processed with ginger juice from fresh ginger(CRGJFG), CR processed with ginger juice from Zinger (CRGJZ), ginger juice from fresh ginger (GJFG) and ginger juice from Zinger (GJZ), and then their urine was collected at different time points for metabolomics analysis. PeakviewTM 1.7 software was applied to analyze the total ion current under positive ion mode; MarkerviewTM 2.0 software was applied for principal component analysis (PCA). The possible biomarkers were screened and their content changes were described according to the searching results in Scifinder and Chemspider databases and related literature reports. The results showed that CR processed with different ginger juice would produce different effects on energy metabolism. Nine possible biomarkers relating to medicinal properties were found as sarcosine, hippuric acid, creatinine, kynurenine, tyrosine, L-tryptophan, nicotinic acid, arachidonic acid and L-proline. L-tryptophan, kynurenine and nicotinic acid were involved in the metabolism of tryptophan; sarcosine, creatinine, L-proline and tyrosine were involved in arginine and proline metabolism; the content of arachidonic acid in urine, precursor of leukotrienes B4, from high to low were CRGJZ, CRGJFG and RCR. The contents of all biomarkers in GJZ group were higher than those in GJFG group, indicating the cold nature of CR was gradually decreased in the following order： RCR, CRGJZ and CRGJFG, and resulting in different anti-inflammatory effects of samples. The results were in consistent with the conclusion that GJFG had hot nature and GJZ had warm nature. The study provided the scientific basis for proper use of different ginger juice as processing assistants. Copyright© by the Chinese Pharmaceutical Association.

[Metabolism of chromium in femur head in aspect of cigarette smoking].

PubMed

Brodziak-Dopierała, Barbara; Kwapuliński, Jerzy; Bogunia, Mariusz; Ahnert, Bozena; Paukszto, Andrzej; Jakubowska, Justyna

2006-01-01

The objective of this study was qualification of content chromium in femur head in aspect of smoking cigarette. Investigated of femur head from habitants of Upper Silesian Region. The content of chromium was marked at non-smoking persons, smoking in past and smoking at present. Determination of contents chromium realized by ASA method (Pye Unicam SP-9) in flame acetylene-oxygen. Higher contents of chromium were observed for smoking people. The most of the correlations described by large values of the correlation factors were concerned Cr with Ni, Cu, Zn, Na.

[Health risk assessment of heavy metals in atmospheric dust of Qingdao City].

PubMed

Zhang, Chun-Rong; Wu, Zheng-Long; Yao, Chun-Hui; Gao, Zong-Jun

2014-07-01

Based on the 89 atmospheric dust samples and soil samples that were collected around Qingdao, we tested and analyzed the contents of Cd, Cr, Cu, Hg, Ni, Pb, Zn. Based on these analysis results, the risk of heavy metals in atmospheric dusts to human health were assessed by using the US EPA Health Risk Assessment Model. Analysis showed that the average contents of Cd, Cr, Cu, Hg, Pb, Zn in the atmospheric dust of Shinan, Shibei and Laoshan districts were the highest. Therefore, the air pollution of these districts was more serious than the districts of Licang, Chengyang and Huangdao. Comparing the average contents of heavy metals in atmospheric dust with those in soil, we found that only the content of Hg in atmospheric dust collected from the districts of Shinan, Shibei and Laoshan was lower than that in the corresponding soil. All the contents of other heavy metals in atmospheric dust were higher than those in corresponding soil. As a whole, the heavy metals in atmospheric dust of Qingdao City showed slight difference and were less harmful to human health. However, it was harmful in some samples to human health if the contents of Cr and Pb in atmospheric dusts of Shinan, Laoshan and Chengyang districts were always kept at such high densities. Besides, the accumulation of heavy metals in atmospheric dust through various approaches and categories may obviously increase the risk of damaging human health.

Milk fatty acid profile of Peruvian Criollo and Brown Swiss cows in response to different diet qualities fed at low and high altitude.

PubMed

Bartl, Karin; Gomez, Carlos A; García, Miriam; Aufdermauer, Tony; Kreuzer, Michael; Hess, Hans Dieter; Wettstein, Hans-Rudolf

2008-12-01

Two identical experimental protocols were followed at 200 and 3,600 m above sea level (a.s.l.) determining the changes of the milk fatty acid (FA) profile of Brown Swiss (BS) and indigenous Peruvian Criollo cows (CR) as a response to diets which were designed to cover the variation in feed quality caused by season. At each site (altitude), six BS and six CR cows, adapted to > 3,500 m a.s.l., were fed three dietary treatments (DS, dry-season forage; RS rainy-season forage; OC, diet optimised to meet the cow's requirements) in a 2 x 2 x 3-factorial arrangement. Intakes of FA and milk yield increased from diet DS (low quality diet) to RS and OC (high quality diet) for both cow types. Milk fat proportions of conjugated linoleic acid (CLA), C18:3 c9,c12,c15, total n-3 and polyunsaturated FA (PUFA) were highest (p < 0.05) with diet OC and higher in the lowlands than in the highlands. Low intakes of diet DS obviously resulted in a ruminal energy deficiency and body lipid mobilisation. The ruminal energy deficiency with diet DS was especially pronounced in BS, apparently reducing biohydrogenation rate and leading to lower proportions of C18:0 and higher proportions of C18:3 c9,c12,c15 in milk fat (p < 0.05). Especially C18:3 c9,c12,c15 intake did not concur with its proportion in milk fat, suggesting a strong dependence on energy status. Milk yield and FA excretion with milk were higher for BS than for CR (p < 0.05) with all three diets although milk fat content was lower (p < 0.05) for BS than CR. Milk fat of BS was richer in CLA and PUFA than milk fat of CR (p < 0.05). The desaturase indices for 18 FA were also higher for BS than CR (p < 0.05), suggesting a slightly higher delta9-desaturase activity for BS, especially with diet DS. Milk fat content was generally higher at the high altitude than at the lowland site (p < 0.05), whereas the FA profile was unexpectedly similar across sites. Various interactions were found among diet type, cow type and altitude (site) indicating that a combination of these factors contributes to the characteristic FA profile of the respective milk.

Effect of titanium on the creep deformation behaviour of 14Cr-15Ni-Ti stainless steel

NASA Astrophysics Data System (ADS)

Latha, S.; Mathew, M. D.; Parameswaran, P.; Nandagopal, M.; Mannan, S. L.

2011-02-01

14Cr-15Ni-Ti modified stainless steel alloyed with additions of phosphorus and silicon is a potential candidate material for the future cores of Prototype Fast Breeder Reactor. In order to optimise the titanium content in this steel, creep tests have been conducted on the heats with different titanium contents of 0.18, 0.23, 0.25 and 0.36 wt.% at 973 K at various stress levels. The stress exponents indicated that the rate controlling deformation mechanism was dislocation creep. A peak in the variation of rupture life with titanium content was observed around 0.23 wt.% titanium and the peak was more pronounced at lower stresses. The variation in creep strength with titanium content was correlated with transmission electron microscopic investigations. The peak in creep strength exhibited by the material with 0.23 wt.% titanium is attributed to the higher volume fraction of fine secondary titanium carbide (TiC) precipitates.

Effects of different lasers on organic/inorganic ratio of radicular dentin.

PubMed

Lopes, F C; Roperto, R; Akkus, A; Akkus, O; Souza-Gabriel, A E; Sousa-Neto, M D

2016-04-01

The aim of this study was to evaluate the chemical stability of endodontic-treated root dentin after different laser irradiations through Raman spectroscopy. Fifty maxillary canines were selected and prepared with K3 system. Roots were randomly distributed into five groups (n = 10) according to the surface treatment: GI (water), GII (NaOCl + EDTA), GIII (NaOCl + EDTA + 980 nm Diode laser), GIV (NaOCl + EDTA+ 1064 nm Nd: YAG laser) and GV (NaOCl + EDTA+ 2780 nm Er,Cr: YSGG laser). Lasers were applied for 20 s. Samples were bisected, and the organic and inorganic content of dentin was analyzed by Raman spectroscopy. Data were submitted to ANOVA and Tukey tests (p < 0.05). None of the surface treatments alter the inorganic content (cts) (p = 0.183). Roots irradiated with Er,Cr: YSGG laser had a reduced collagen content (GV-290.7 ± 41.7) compared with the water-treated roots (GI-328.3 ± 63.5) and those treated with NaOCl + EDTA (GII-333.9 ± 55.8). Roots irradiated with Er,Cr: YSGG laser also showed a higher inorganic/organic ratio (GV-9.5 ± 1.1) than roots treated with water (GI-7.7 ± 1.5), NaOCl + EDTA (GII-8.0 ± 1.4) and diode laser (GIII-8.2 ± 1.6). Both organic and inorganic contents increased from cervical to apical thirds in all groups. None of the surface treatments were able to promote changes in the inorganic content of the root dentin; treatment with NaOCl + EDTA combined with Er,Cr: YSGG altered collagen.

Volatile-rich komatiitic and picritic melt inclusions in Cr-spinel beach sand from Gorgona Island, Colombia

NASA Astrophysics Data System (ADS)

Shimizu, K.; Shimizu, N.; Suzuki, K.; Tatsumi, Y.; Komiya, T.; Maruyama, S.

2007-12-01

Volatile content of komatiite is a key to constrain thermal evolution of the deep Earth. We report volatile contents with major and trace element compositions of melt inclusions (MIs) in chromian spinel (Cr-spinel) from beach sands of Gorgona Island, Colombia. Gorgona Island is ~90 Ma volcanic island, where picrites and the world-youngest komatiites occur. As Cr-spinel is dense and rigid oxide mineral that crystallizes only at early stages of crystallization, it is considered to be a superior container for retaining primitive melt, even including volatiles. Volatile (H2O, CO2, S, F and Cl) and trace element (K2O, Sr, Y, Zr, Nb, Ba, La, Ce, Sm, Dy, Yb) compositions of ~80 MIs were analyzed by SIMS (Cameca-1280 and 3f, respectively) at WHOI. MIs in the Cr-spinel from Gorgona Is. are classified into three types by their host Cr-spinel compositions such as low-Ti (P-type), high-Ti with high-Cr# (BK-type) and high-Ti with low-Cr# (K-type). MIs of P-type, BK-type and K-type are mostly in compositional ranges of picrite, high TiO2 komatiite (some basalt) and low TiO2 komatiite in Gorgona Island, respectively. Water content of P-type MIs is variable, ranging from 0.05 to 0.9 wt%, whereas those of BK and K-type MIs are limited (< 0.1 wt%). On the other hand, CO2 contents of BK-type and K- type MIs are highly scattered (40 to 4200 ppm), whereas that of P-type is relatively constant at ~200 ppm. All MIs with high CO2 content (>500 ppm) do not contain (shrinkage) bubbles and many of them are low in K2O. H2O/K2O, CO2/K2O, S/K2O and F/K2O ratios are positively correlated with Y/Sr ratios, indicating degassing trends of melt at crystallization, magma mixing and/or assimilation. Undegassed H2O/K2O, CO2/K2O, S/K2O and F/K2O ratios of komatiitic (picritic) melt are estimated to be ~10 (~40), ~80 (n.d.), ~7(~3) and ~1(~0.5), respectively, which are much higher than those estimated for the depleted source mantle of the MORB [1.6, 0.7, 1.6 and 0.2, respectively; Salters, V. & Stracke, A. (2004), Composition of the depleted mantle. Geochem. Geophys. Geosys. 5 (2003GC000597)]. The results suggest that Gorgona komatiite and picrite magmas were derived from volatile-rich sources. CO2 degassing might also have contributed to eruption of high-density magmas to the surface. In addition, H2O, S, F and Cl contents in MIs in olivine from a picrite were identical to those of P-type MIs in Cr-spinel, but CO2 in olivine-hosted MIs were considerably lower (~50 ppm) than those in Cr-spinel. This indicates that entrapment pressure for MIs in Cr-spinel is likely to be greater than that for MIs in olivine. Therefore, in order to evaluate the volatile contents of undegassed magmas from oceanic islands, melt inclusions in Cr-spinel beach sand could be very useful.

Chromium toxicity tolerance of Solanum nigrum L. and Parthenium hysterophorus L. plants with reference to ion pattern, antioxidation activity and root exudation.

PubMed

UdDin, Islam; Bano, Asghari; Masood, Sajid

2015-03-01

Chromium (Cr), being a highly toxic metal, adversely affects the mineral uptake and metabolic processes in plants when present in excess. The current study was aimed at investigating the Cr accumulation in various plant tissues and its relation to the antioxidation activity and root exudation. Plants were grown in soil spiked with different concentrations of Cr for three weeks in pots and analysed for different growth, antioxidants and ion attributes. Furthermore, plants treated with different concentrations of Cr in pots were shifted to rhizobox-like system for 48h and organic acids were monitored in the mucilage dissolved from the plant root surface, mirroring rhizospheric solution. The results revealed that the Cr application at 1mM increased the shoot fresh and dry weight and root dry weight of Solanum nigrum, whereas the opposite was observed for Parthenium hysterophorus when compared with lower levels of Cr (0.5mM) or control treatment. In both plant species, Cr and Cl concentrations were increased while Ca, Mg and K concentrations in root, shoot and root exudates were decreased with increasing levels of Cr. Higher levels of Cr treatments enhanced the activities of SOD, POD and proline content in leaves of S. nigrum, whereas lower levels of Cr treatment were found to have stimulatory effects in P. hysterophorus. P. hysterophorus exhibited highest exudation of organic acid contents. With increasing levels of Cr treatments, citric acid concentration in root exudates increased by 35% and 44% in S. nigrum, whereas 20% and 76% in P. hysterophorus. Cr toxicity was responsible for the shoot growth reduction of S. nigrum and P. hysterophorus, however, shoot growth response was different at different levels of applied Cr. Consequently, Cr stress negatively altered the plant physiology and biochemistry. However, the enhanced antioxidant production, Cl uptake and root exudation are the physiological and biochemical indicators for the plant adaptations in biotic systems polluted with Cr. Copyright © 2014 Elsevier Inc. All rights reserved.

Reduction kinetics of hexavalent chromium in soils and its correlation with soil properties.

PubMed

Xiao, Wendan; Zhang, Yibin; Li, Tingqiang; Chen, Bao; Wang, Huan; He, Zhenli; Yang, Xiaoe

2012-01-01

The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that the reduction of Cr(VI) can be described by a first-order reaction. The reduction rates of Cr(VI) in the seven soils decreased in the order: Udic Ferrisols > Stagnic Anthrosols > Calcaric Regosols > Mollisol > Typic Haplustalf > Periudic Argosols > Ustic Cambosols. Simple correlation analysis revealed that the reduction of Cr(VI) in soils was positively related to organic matter content, dissolved organic matter content, Fe(II) content, clay fraction, and to the diversity index of the bacterial community but negatively correlated with easily reducible Mn content. Using stepwise regression, the reduction of Cr(VI) in soil could be quantitatively predicted by the measurement of dissolved organic matter content, Fe(II) content, pH, and soil particle size distribution, with a fitting level of 95.5%. The results indicated that the reduction of Cr(VI) in natural soils is not controlled by a single soil property but is the result of the combined effects of dissolved organic matter, Fe(II), pH, and soil particle size distribution. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Preparation and Cr(VI) removal performance of corncob activated carbon.

PubMed

Li, Hongyan; Gao, Pei; Cui, Jianguo; Zhang, Feng; Wang, Fang; Cheng, Jici

2018-05-12

Corncob activated carbon (CCAC) was prepared by a H 3 PO 4 activation method. The optimum conditions for the preparation of CCAC were determined by orthogonal experiments. The effects of pH, reaction time, CCAC dosage, and hexavalent chromium (Cr(VI)) concentrations on Cr(VI) removal by CCAC were studied. Corn straw activated carbon (CSAC) was also prepared using the optimum preparation conditions determined for CCAC. The properties of samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that the optimum preparation conditions for CCAC were as follows: a mass of corncob of 10 g; a mass ratio of corncob to H 3 PO 4 of 1:2; a 5% H 3 BO 3 content of 10 mL; an impregnation time of 45 min; a carbonization temperature of 500 °C. The optimum conditions for the removal of Cr(VI) were as follows: pH < 9; temperature, 308 K; rotation speed, 150 r min -1 ; reaction time, 60 min; CCAC dosage, 1 g L -1 . The Cr(VI) removal rate was above 98%, and the maximum adsorption capacity of CCAC was 9.985 mg g -1 . The concentration of residual Cr(VI) in water was less than 0.05 mg L -1 . FTIR showed that the surfaces of the samples had more oxygen-containing functional groups, which promoted the adsorption. XRD showed that CCAC and CSAC had similar peaks and that these peaks promoted the adsorption of Cr(VI). BET indicated that the number of pores in the samples followed the order CCAC > CSAC > CAC. SEM showed that the CCAC surface had a more porous structure, which enhanced adsorption. EDS showed that the C contents of CCAC and CSAC were much higher than that of CAC. Cr(VI) adsorption on CCAC followed quasi-second-order kinetics and was in accordance with a Langmuir adsorption isotherm, with monolayer adsorption. The adsorption reaction was endothermic, where higher temperatures increased the degree of spontaneous reaction.

Water Vapor Effects on the Oxidation Behavior of Fe-Cr and Ni-Cr Alloys in Atmospheres Relevant to Oxy-fuel Combustion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mu, N.; Jung, K. Y.; Yanar, N. M.

2011-10-01

The oxidation behavior of a number of Fe–Cr- and Ni–Cr-based alloys was studied in atmospheres relevant to oxyfuel combustion at 650 °C. Oxidation was greatly enhanced in ferritic model alloys exposed in low p(O{sub 2}) CO{sub 2} + 30%H{sub 2}O and Ar + 30%H{sub 2}O gases. Rapidly growing iron oxides appear to be porous and gas permeable. Transition from non-protective to protective oxidation occurs on alloys with higher Cr contents between 13.5 and 22 wt% in H{sub 2}O. Excess oxygen, usually found in the actual oxyfuel combustion environments, disrupts the selective oxidation of Fe–Cr alloys by accelerating vaporization of early-formedmore » Cr{sub 2}O{sub 3} in combination with accelerated chromia growth induced by the H{sub 2}O. Rapid Cr consumption leads to the nucleation and rapid growth of iron oxides. On the contrary, Ni–Cr alloys are less affected by the presence of H{sub 2}O and excess O{sub 2}. The difference between Fe–Cr and Ni–Cr alloys is not clear but is postulated to involve less acceleration of chromia growth by water vapor for the latter group of alloys.« less

[Response of Nostoc flageliforme cell to Cu2+, Cr2+ and Pb2+ stress].

PubMed

Guo, Jinying; Shi, Mingke; Zhao, Yanli; Ren, Guoyan; Yi, Junpeng; Niu, Leilei; Li, Juan

2013-06-04

This study aimed to investigate the effects of Cu2+, Cr2+ and Pb2+ stress on Nostoc flagelliforme cell. The response of Nostoc flagelliforme cell was analyzed under the stress. The modified BG11 culture medium containing different heavy metal ions of 0, 0.1, 1.0, 10, 100 mg/L was used to cultivate Nostoc flagelliforme cell at 25 degrees C and light intensity of 80 micromol/(m x s). Electrolyte leakage, the activities of superoxide dismutase, the content of malondialdehyde, proline, soluble protein and trehalose were analyzed. Under 1 - 100 mg/L Cu2+, Cr2+ and Pb2+ stress, electrolyte leakage and malondialdehyde contents in Nostoc flagelliforme cell were higher than those in the control group during heavy metal ions stress. Meanwhile, superoxide dismutase activity increased slightly under 10 mg/L, but was lower afterwards. The contents of proline, soluble protein and trehalose increased under 10 mg/L heavy metal ions stress, while declined under extreme heavy metal ions stress (100 mg/L). Nostoc flagelliforme cell has resistance to low heavy metal ions stress, but is damaged badly under extreme heavy metal ions stress.

Relationship between Microstructure and Corrosion Behavior of Martensitic High Nitrogen Stainless Steel 30Cr15Mo1N at Different Austenitizing Temperatures.

PubMed

Jiang, Zhouhua; Feng, Hao; Li, Huabing; Zhu, Hongchun; Zhang, Shucai; Zhang, Binbin; Han, Yu; Zhang, Tao; Xu, Dake

2017-07-27

The relationship between microstructure and corrosion behavior of martensitic high nitrogen stainless steel 30Cr15Mo1N at different austenitizing temperatures was investigated by microscopy observation, electrochemical measurement, X-ray photoelectron spectroscopy analysis and immersion testing. The results indicated that finer Cr-rich M₂N dispersed more homogeneously than coarse M 23 C₆, and the fractions of M 23 C₆ and M₂N both decreased with increasing austenitizing temperature. The Cr-depleted zone around M 23 C₆ was wider and its minimum Cr concentration was lower than M₂N. The metastable pits initiated preferentially around coarse M 23 C₆ which induced severer Cr-depletion, and the pit growth followed the power law. The increasing of austenitizing temperature induced fewer metastable pit initiation sites, more uniform element distribution and higher contents of Cr, Mo and N in the matrix. In addition, the passive film thickened and Cr₂O₃, Cr 3+ and CrN enriched with increasing austenitizing temperature, which enhanced the stability of the passive film and repassivation ability of pits. Therefore, as austenitizing temperature increased, the metastable and stable pitting potentials increased and pit growth rate decreased, revealing less susceptible metastable pit initiation, larger repassivation tendency and higher corrosion resistance. The determining factor of pitting potentials could be divided into three stages: dissolution of M 23 C₆ (below 1000 °C), dissolution of M₂N (from 1000 to 1050 °C) and existence of a few undissolved precipitates and non-metallic inclusions (above 1050 °C).

Fracture toughness and sliding properties of magnetron sputtered CrBC and CrBCN coatings

NASA Astrophysics Data System (ADS)

Wang, Qianzhi; Zhou, Fei; Ma, Qiang; Callisti, Mauro; Polcar, Tomas; Yan, Jiwang

2018-06-01

CrBC and CrBCN coatings with low and high B contents were deposited on 316L steel and Si wafers using an unbalanced magnetron sputtering system. Mechanical properties including hardness (H), elastic modulus (E) and fracture toughness (KIc) as well as residual stresses (σ) were quantified. A clear correlation between structural, mechanical and tribological properties of coatings was found. In particular, structural analyses indicated that N incorporation in CrBC coatings with high B content caused a significant structural evolution of the nanocomposite structure (crystalline grains embedded into an amorphous matrix) from nc-CrB2/(a-CrBx, a-BCx) to nc-CrN/(a-BCx, a-BN). As a result, the hardness of CrBC coating with high B content decreased from 23.4 to 16.3 GPa but the fracture toughness was enhanced. Consequently, less cracks initiated on CrBCN coatings during tribological tests, which combined with the shielding effect of a-BN on wear debris, led to a low friction coefficient and wear rate.

Nanoscale assembly of high-temperature oxidation-resistant nanocomposites.

PubMed

Peng, Xiao

2010-02-01

Structural considerations for designing a high-temperature oxidation-resistant metallic material are proposed, based on the dependence of the material structure on a promotion of the development of a protective scale of chromia or alumina. The material should have numerous sites on its surface for nucleating the protective oxides at the onset of oxidation and abundant grain boundaries in deeper areas for simultaneously supplying sufficient flux of the protective-oxide-forming elements toward the surface for a rapid linkage of the oxide nuclei through their lateral growth. Based on these considerations, we fabricated, using an electrochemical deposition method, novel nanocomposites which have a nanocrystalline metal matrix containing Cr and/or Al nanoparticles dispersed at the nano length scale. The validity of the design considerations is verified by comparing the high-temperature oxidation of a typical Ni-Cr nanocomposite system with two types of conventional Ni-Cr materials having similar or higher Cr content but different structure: one is a composite having a nanocrystalline Ni matrix containing Cr microparticles dispersed at the microscale and the other are micron-grained Ni-Cr alloys with the Cr distribution at the atomic length scale.

Nanoscale assembly of high-temperature oxidation-resistant nanocomposites

NASA Astrophysics Data System (ADS)

Peng, Xiao

2010-02-01

Structural considerations for designing a high-temperature oxidation-resistant metallic material are proposed, based on the dependence of the material structure on a promotion of the development of a protective scale of chromia or alumina. The material should have numerous sites on its surface for nucleating the protective oxides at the onset of oxidation and abundant grain boundaries in deeper areas for simultaneously supplying sufficient flux of the protective-oxide-forming elements toward the surface for a rapid linkage of the oxide nuclei through their lateral growth. Based on these considerations, we fabricated, using an electrochemical deposition method, novel nanocomposites which have a nanocrystalline metal matrix containing Cr and/or Al nanoparticles dispersed at the nano length scale. The validity of the design considerations is verified by comparing the high-temperature oxidation of a typical Ni-Cr nanocomposite system with two types of conventional Ni-Cr materials having similar or higher Cr content but different structure: one is a composite having a nanocrystalline Ni matrix containing Cr microparticles dispersed at the microscale and the other are micron-grained Ni-Cr alloys with the Cr distribution at the atomic length scale.

Heavy metal contents and transfer capacities of Phragmites australis and Suaeda salsa in the Yellow River Delta, China

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Bai, Junhong; Wang, Wei; Huang, Laibing; Zhang, Guangliang; Wang, Dawei

2018-04-01

Plant samples including roots, stems and leaves of Phragmites australis and Suaeda salsa were collected in the short-term flooding and tidal flooding wetlands of the Yellow River Delta of China. Six heavy metals (e.g., As, Cd, Cr, Cu, Pb, and Zn) were measured in roots, stems and leaves of each plant species using inductively coupled plasma atomic absorption spectrometry (ICP-AAS) to investigate the levels, and transfer capabilities of heavy metals in these two plant species. Our results showed that in the tidal flooding wetlands, the contents of As, Cr and Cd in roots of Phragmites australis and Suaeda salsa were higher than those in their stems and leaves. Suaeda salsa showed higher contents of Pb and Zn in leaves than those in roots and stems, whereas lower levels of Pb and Zn were observed in Phragmites australis. In the short-term flooding wetlands, heavy metal contents exhibited a big difference between different tissues of Phragmites australis and Suaeda salsa, and both plant species showed higher levels of Pb and Zn in leaves. Suaeda salsa roots enriched more As and Cd, whereas higher enrichment levels were observed in Phragmites australis leaves, which indicated different transfer capacities of these two wetland plants. The transfer factors for stems and leaves of Phragmites australis in the tidal flooding wetlands significantly differed from those in the short-term flooding wetlands, however, no significant differences in transfer factors for stems and leaves of Suaeda salsa were observed between these two types of wetlands.

The influence of Cr content on the mechanical properties of ODS ferritic steels

NASA Astrophysics Data System (ADS)

Li, Shaofu; Zhou, Zhangjian; Jang, Jinsung; Wang, Man; Hu, Helong; Sun, Hongying; Zou, Lei; Zhang, Guangming; Zhang, Liwei

2014-12-01

The present investigation aimed at researching the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steels with different Cr content, which were fabricated through a consolidation of mechanical alloyed (MA) powders of 0.35 wt.% nano Y2O3 dispersed Fe-12.0Cr-0.5Ti-1.0W (alloy A), Fe-16.0Cr-0.5Ti-1.0W (alloy B), and Fe-18.0Cr-0.5Ti-1.0W (alloy C) alloys (all in wt.%) by hot isostatic pressing (HIP) with 100 MPa pressure at 1150 °C for 3 h. The mechanical properties, including the tensile strength, hardness, and impact fracture toughness were tested by universal testers, while Young's modulus was determined by ultrasonic wave non-destructive tester. It was found that the relationship between Cr content and the strength of ODS ferritic steels was not a proportional relationship. However, too high a Cr content will cause the precipitation of Cr-enriched segregation phase, which is detrimental to the ductility of ODS ferritic steels.

Crystal-Chemical Correlations in Chromites from Kimberlitic and Non-Kimberlitic Sources.

NASA Astrophysics Data System (ADS)

Freckelton, C. N.; Flemming, R. L.

2009-05-01

This study explores the utility of micro X-ray diffraction (μXRD) as a tool for diamond exploration, as a compliment to current industry-standard techniques such as electron probe microanalysis (EPMA). Here we examine chromite. As one of the first phases to crystallize in mantle rocks, it is a useful indicator of upper mantle magmatic conditions in rocks that have been sampled by kimberlites. In addition, chromite does not alter easily from chemical and physical weathering processes. As such, chromite is a useful kimberlite indicator mineral in diamond exploration. We present correlations between crystal structure (unit cell) and chemical composition of chromite, (Fe,Mg)[Cr, Al]2O4, using correlated μXRD and EPMA data for 133 chromites from a three source locations: Two kimberlite sources and one non-kimberlitic source from an Archean granite/greenstone terrain. Quantitative analysis was performed using Electron Probe Microanalysis (EPMA) at Mineral Services, South Africa, prior to the loan of the samples. Randomly-oriented chromite grains, approximately 500 μm in diameter, were analyzed as previously mounted for EPMA. Micro X-ray-diffraction was performed using a Bruker D8-Discover Diffractometer, with θ-θ geometry, with CuKα radiation, operating at 40 kV and 40 mA, with nominal beam diameter of 500 μm. The data were collected in omega scan mode. Two dimensional General Area Detector Diffraction System (GADDS) images were collected for 20 minutes per image, and integrated to produce one-dimensional plots of intensity versus 2θ, for subsequent unit cell refinement using CELREF. Although all samples in this study were considered to be 'chromite', a plot of Cr/(Cr+Al) versus Fe2+/(Fe2++Mg) shows extensive substitution among four dominant members: chromite (FeCr2O4), magnesio-chromite (MgCr2O4), spinel (MgAl2O4), and hercynite (FeAl2O4), where Mg and Fe2+ substitute for one another on the tetrahedral site, and Cr and Al substitute for one another on the octahedral site. Our data are widely variable as compared to the field occupied by chromite inclusions in diamonds (high Cr and Mg (˜60 wt %) and very low Ti (˜0.40 wt %). Plots of the unit cell parameter, ao, versus composition demonstrate a decrease in unit cell size with increasing Al content (and corresponding decrease in Cr content), consistent with a smaller cation radius for Al versus Cr (Al=0.675 Å and Cr=0.905 Å). The trend in unit cell size is unlikely to be effected by Mg-Fe substitution because of the very small difference in their tetrahedral cation radii (Fe2+=0.835 Å and Mg=0.86 Å). Initial plots of composition versus unit cell parameter were clearly able to distinguish a difference between unit cell of kimberlitic chromites and non-kimberlitic chromites. The significantly higher Cr content in kimberlitic chromites (radius=0.905 Å), and correspondingly higher Al content in non-kimberlitic chromites (radius=0.675 Å), results in a striking bimodal distribution in unit cell parameter, ao, where kimberlitic chromites have a larger unit cell (> 8.3 Å) than non-kimberlitic chromites (< 8.3 Å). This preliminary data provides a useful starting point for screening minerals from naturally relevant chromite solid solutions using their corresponding unit cell parameters. Future work will examine which site substitutions (octahedral versus tetrahedral) are affecting the unit cell as well as the effect of cation order-disorder on unit cell parameters.

An assessment of the risk of element contamination of urban and industrial areas using Taraxacum sect. Ruderalia as a bioindicator.

PubMed

Fröhlichová, Alena; Száková, Jiřina; Najmanová, Jana; Tlustoš, Pavel

2018-02-19

Central Bohemia (Czech Republic) has highly developed industry and a dense rail network. Here, we aimed to determine the content of risk elements in dandelion plants (Taraxacum sect. Ruderalia) growing near train stations, industrial enterprises, and in the city parks of 16 cities in the Central Bohemian region. The highest element contents in the soils were found in industrial areas affected by the historical mining and smelting activities; contemporary industry showed no substantial effect on the soil element contents. The median values of element contents (As, Be, Cd, Co, Cr, Cu, Ni, Pb, and Zn) at the railway station sites were the highest among the monitored sites, where the differences between park and station sites were significant for Be, Co, and Zn. Although the intensity of the traffic at the individual stations differed, we found that long-term regular traffic enhanced the element contents in the soils and, subsequently, in the plants. For Cd, Co, Cr, Cu, Pb, V, and Zn, the highest median element contents were found in plant roots, regardless of the sampling site. For Cd and Zn, the contents in leaves were higher than in the inflorescences, and the opposite pattern was recorded for Co and Cu. As and Be were distributed equally among the plant parts. Among the sampling sites, the As, Be, Cd, Zn, and Pb contents in the plant roots tended to have higher median values at the station sites, confirming the results of our soil analyses. We detected a fairly good correlation between soil and plant content for cadmium, regardless of the sampling site, soil element content, or analyzed part of the plant. Thus, we propose that dandelion is a suitable bioindicator of cadmium pollution of soil.

Physiological responses and tolerance of kenaf (Hibiscus cannabinus L.) exposed to chromium.

PubMed

Ding, Han; Wang, Guodong; Lou, Lili; Lv, Jinyin

2016-11-01

Selection of kenaf species with chromium (Cr) tolerance and exploring the physiological mechanisms involved in Cr tolerance are crucial for application of these species to phyto-remediation. In the present study, a hydroponic experiment was conducted to investigate the variation in two kenaf cultivars, K39-2 and Zhe50-3 under Cr stress. At the same Cr concentration, the tolerance index (TI) of K39-2 was higher than that of Zhe50-3, indicating that K39-2 may be more tolerant to Cr than Zhe50-3. It was also observed that high concentration of chromium was accumulated both in the shoots and the roots of Hibiscus cannabinus L. The leaves of K39-2 accumulated 4760.28mgkg(-1) of dry weight under 1.50mM Cr stress, and the roots accumulated 11,958.33mgkg(-1). Physiological response shows that the antioxidant enzymes' superoxide dismutase (SOD), catalase activity (CAT) and peroxidase (POD) activities increased in the leaves and decreased in roots of the Cr-stressed plants nearly compared to the control. Moreover, the variation of antioxidant enzymes activities indicated Zhe50-3 was more vulnerable than K39-2, and the contents of the non-protein thiol pool (GSH, NPT and PCs) were higher in K39-2 than Zhe50-3 with the increased Cr concentration. Based on the observations above, it can be concluded that the well-coordinated physiological changes confer a greater Cr tolerance to K39-2 than Zhe50-3 under Cr exposure, and Hibiscus cannabinus L. has a great accumulation capacity for chromium. Copyright © 2016 Elsevier Inc. All rights reserved.

Relationship between Microstructure and Corrosion Behavior of Martensitic High Nitrogen Stainless Steel 30Cr15Mo1N at Different Austenitizing Temperatures

PubMed Central

Jiang, Zhouhua; Feng, Hao; Zhu, Hongchun; Zhang, Shucai; Zhang, Binbin; Han, Yu; Zhang, Tao; Xu, Dake

2017-01-01

The relationship between microstructure and corrosion behavior of martensitic high nitrogen stainless steel 30Cr15Mo1N at different austenitizing temperatures was investigated by microscopy observation, electrochemical measurement, X-ray photoelectron spectroscopy analysis and immersion testing. The results indicated that finer Cr-rich M2N dispersed more homogeneously than coarse M23C6, and the fractions of M23C6 and M2N both decreased with increasing austenitizing temperature. The Cr-depleted zone around M23C6 was wider and its minimum Cr concentration was lower than M2N. The metastable pits initiated preferentially around coarse M23C6 which induced severer Cr-depletion, and the pit growth followed the power law. The increasing of austenitizing temperature induced fewer metastable pit initiation sites, more uniform element distribution and higher contents of Cr, Mo and N in the matrix. In addition, the passive film thickened and Cr2O3, Cr3+ and CrN enriched with increasing austenitizing temperature, which enhanced the stability of the passive film and repassivation ability of pits. Therefore, as austenitizing temperature increased, the metastable and stable pitting potentials increased and pit growth rate decreased, revealing less susceptible metastable pit initiation, larger repassivation tendency and higher corrosion resistance. The determining factor of pitting potentials could be divided into three stages: dissolution of M23C6 (below 1000 °C), dissolution of M2N (from 1000 to 1050 °C) and existence of a few undissolved precipitates and non-metallic inclusions (above 1050 °C). PMID:28773221

Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater, Akaki, Ethiopia

NASA Astrophysics Data System (ADS)

Fitamo, Daniel; Itana, Fisseha; Olsson, Mats

2007-02-01

The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0-20 and 30-50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0-20 cm; and Cr, Ni, Cu, Cd, and Zn at 30-50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction. Generally, a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health threat through their introduction into the food chain in the wastewater irrigated soils.

[Study on distribution characteristics and potential ecological risk of soil heavy metals in the Yellow River beach region in Kaifeng City].

PubMed

Zhang, Peng-yan; Qin, Ming-zhou; Chen, Long; Hu, Chang-hui; Zhao, Ya-ping; Dong, Wei-jun

2013-09-01

The distributions, soil environment status and potential ecological risk of heavy metals were studied in beach soil of returning the cropland into Yellow River beach region in Kaifeng by the Nemerows and Håkansons methods. The results showed that (1) as Among the average contents of the five heavy metals Pb, Cr, Hg, As and Cd, the highest was the average content of Cr, and the lowest was the average content of Pb and Hg. In addition to Hg, the coefficients of variation of other heavy metals were relatively small, indicating that the content of heavy metals was quite different at different sites, and to some extent, relecting that Hg, As and Pb were the major elements polluting the soil, among which, Pb pollution was the pollution with universality. There was little difference in the contents of Cr and Cd from village to village the coefficient of variation was small, and the contents were below the national standard level. (2) There was significant difference in the spatial distribution of soil heavy metal elements in the upper, the middle and lower sections of the study area. The upper section was clean, the middle section was slightly polluted, and the lower section was enriched with pollutants. (3) The distribution of heavy metals in the beach region inside and outside the levees of Yellow River was closely related to the distribution of the residential regions. In the upper section of the beach region (southwest), the population was large and the contents of heavy metals were high. The contents of heavy metals were lower in the near river zone than outside the levees of Yellow River. And the heavy metal contents in the middle and lower section were higher than those outside the levees of Yellow River, while the lower section (northwest) showed a tendency of pollution enrichment. (4) In the view of the average individual potential ecological risk index of heavy metals (E(r)i), the potential ecological risk of Hg reached intense levels, and the potential ecological risk of Pb's contribution to the integrated risk was 50.5%, which was the heavy metal with highest ecological risks. Cd and Pb had a moderate ecological risk, while As and Cr had minor ecological risk. Ecological hazards of heavy metals ranked in the ascending order of Hg > Pb > As > Cd > Cr. (5) The ecological hazard of the heavy metals was ranked in the order Hg > Cd > As > Pb > Cr. Based on the potential ecological risk level corresponding to the RI values, it was shown that there was moderate potential ecological risks of heavy metals in the Yellow River beach region in Kaifeng.

Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

NASA Astrophysics Data System (ADS)

Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

2017-01-01

This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

Annual changes and seasonal variations of Cr in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Haixia, Li; Zhang, Longlei; Li, Jiangmin; Nan, Nan

2017-04-01

Many bays have been polluted by Cr due to the rapid increasing of industry, hence understanding the temporal change trends and seasonal patterns is essential to pollution control and environmental remediation. Jiaozhou Bay is a semi-closed bay located in Shandong Province, China. This paper analyzed the annual changes and seasonal variations of Cr in Jiaozhou Bay in 1979-1983. Results showed that for annual changes, Cr contents were showing decreasing trend. For seasonal variations, Cr contents were in order of spring > summer > autumn. In generally, the pollution level of Cr contents in the early stage of China’s Reform and Opening-up was still low. These results were meaningful as basic information for pollution control and environmental remediation in this Bay.

Microstructural evolution with various Ti contents in Fe-based hardfacing alloys using a GTAW technique

NASA Astrophysics Data System (ADS)

Hsieh, Chih-Chun; Liu, Yi-Chia; Wang, Jia-Siang; Wu, Weite

2014-07-01

The aim of this study is to discuss the effect of microstructural development with different Ti contents in Fe-based hardfacing alloys. A series of Fe-Cr-C-Si-Mn-xTi alloy fillers was deposited on SS400 low carbon steel substrate using oscillating gas tungsten arc welding. The microstructure in the Fe-based hardfacing alloy without Ti content addition included: the primary γ, eutectic γ+(Fe,Cr)3C, eutectic γ+(Fe,Cr)2C and martensite. With increasing Ti contents, the microstructures showed the primary TiC carbide, γ phase and eutectic γ+(Fe,Cr,Ti)3C. The amount and size of TiC carbide in the hardfacing layers increased as the Ti content increased. However, the eutectic γ+(Fe,Cr,Ti)3C content decreased as the Ti content increased. According to the results of the hardness test, the lowest hardness value (HRC 54.93) was found with 0% wt% Ti and the highest hardness (HRC 60.29) was observed with 4.87 wt% Ti.

Measuring the content of 17 elements in the flesh of Prunus cerasifera and its cultivars by ICP-MS.

PubMed

Shen, Jing; Xue, Hai-Yan; Li, Gai-Ru; Lu, Yi; Yao, Jun

2014-09-01

The present study compared the contents of inorganic elements in the pulp of purple, red, and yellow Prunus cerasifera with its cultivars. A method was established for the analysis of 17 kinds of trace elements (K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Be, Li, Se, Sr, Cr, Pb, Cd, As and Hg) in the flesh of Prunus cerasifera by microwave digestion-ICP-MS. The detection method is simple and quick, yet shoes high precision and high sensitivity. The recovery rate of 17 elements ranged, from 93.5% to 110.4%. The analysis results showed that the contents of 17 elements in the flesh of purple, red, and yellow Prunus cerasifera and its cultivars are similar, containing extremely rich K elements (as high as 1 per thousand) and higher contents of Ca, Mg, Na, Fe and Mn. The contents of Cu, Zn, Li, Se, Sr and Cr are also present. The contents of Pb, Cd, As, Hg and other harmful element are either very low or not detectable. The experimental results for the study of trace elements in pulp of Prunus cerasifera and its cultivars provide empirical data for. future research in this area.

Levels and predictors of airborne and internal exposure to chromium and nickel among welders--results of the WELDOX study.

PubMed

Weiss, Tobias; Pesch, Beate; Lotz, Anne; Gutwinski, Eleonore; Van Gelder, Rainer; Punkenburg, Ewald; Kendzia, Benjamin; Gawrych, Katarzyna; Lehnert, Martin; Heinze, Evelyn; Hartwig, Andrea; Käfferlein, Heiko U; Hahn, Jens-Uwe; Brüning, Thomas

2013-03-01

The objective of this analysis was to investigate levels and determinants of exposure to airborne and urinary chromium (Cr, CrU) and nickel (Ni, NiU) among 241 welders. Respirable and inhalable welding fume was collected during a shift, and the metal content was determined using inductively coupled plasma mass spectrometry. In post-shift urine, CrU and NiU were measured by means of graphite furnace atom absorption spectrometry, with resulting concentrations varying across a wide range. Due to a large fraction below the limits of quantitation we applied multiple imputations to the log-transformed exposure variables for the analysis of the data. Respirable Cr and Ni were about half of the concentrations of inhalable Cr and Ni, respectively. CrU and NiU were determined with medians of 1.2 μg/L (interquartile range <1.00; 3.61) and 2.9 μg/L (interquartile range <1.50; 5.97). Furthermore, Cr and Ni correlated in respirable welding fume (r=0.79, 95% CI 0.74-0.85) and urine (r=0.55, 95% CI 0.44-0.65). Regression models identified exposure-modulating variables in form of multiplicative factors and revealed slightly better model fits for Cr (R(2) respirable Cr 48%, CrU 55%) than for Ni (R(2) respirable Ni 42%, NiU 38%). The air concentrations were mainly predicted by the metal content in electrodes or base material in addition to the welding technique. Respirable Cr and Ni were good predictors for CrU and NiU, respectively. Exposure was higher when welding was performed in confined spaces or with inefficient ventilation, and lower in urine when respirators were used. In conclusion, statistical modelling allowed the evaluation of determinants of internal and external exposure to Cr and Ni in welders. Welding parameters were stronger predictors than workplace conditions. Airborne exposure was lowest inside respirators with supply of purified air. Copyright © 2012 Elsevier GmbH. All rights reserved.

Bioaccumulation of elements in three selected mushroom species from southwest Poland.

PubMed

Mleczek, Mirosław; Siwulski, Marek; Mikołajczak, Patrycja; Goliński, Piotr; Gąsecka, Monika; Sobieralski, Krzysztof; Dawidowicz, Luiza; Szymańczyk, Mateusz

2015-01-01

The contents of 16 minerals and trace elements (Ag, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Pt, Ti and Zn) were analyzed in edible mushrooms (Leccinum scabrum, Boletus edulis and Boletus badius) collected in southwest Poland. Content of Co, Ni and Pb was similar in all tested mushroom species, while content of Ag, Ca, Cd, Hg and Ti was significantly higher in B. edulis than in L. scabrum and B. badius. The largest differences between these species were observed for Fe and Zn accumulation. The highest contents of these elements were noted in B. badius bodies (202 ± 88 and 137 ± 24 mg kg(-1) dry matter, respectively), lower in B. edulis (131 ± 99 and 89 ± 26 mg kg(-1) dry matter, respectively) and lowest in L. scabrum. Differences in As, Cu and Cr content between tested species were observed mainly between L. scabrum and B. badius fruiting bodies. Content of Pt was below 0.01 mg kg(-1) dry matter). In the case of Mg and Mn accumulation, differences between B. edulis and B. badius were not observed (478 and 440 mg kg(-1) dry matter for Mg and 23 and 19 mg kg(-1) dry matter for Mn), and the results showed significantly higher content of these elements than in L. scabrum bodies (312 and 10 mg kg(-1) dry matter, respectively). It is worth underlining that clear accumulation shown by the bioconcentration factor (BCF>1) observed for all three mushroom species was noted in the case of elements Ag, Cd, Co, Cu, Hg, Ni and Zn only.

Trace element emissions from spontaneous combustion of gob piles in coal mines, Shanxi, China

USGS Publications Warehouse

Zhao, Y.; Zhang, Jiahua; Chou, C.-L.; Li, Y.; Wang, Z.; Ge, Y.; Zheng, C.

2008-01-01

The emissions of potentially hazardous trace elements from spontaneous combustion of gob piles from coal mining in Shanxi Province, China, have been studied. More than ninety samples of solid waste from gob piles in Shanxi were collected and the contents of twenty potentially hazardous trace elements (Be, F, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Hg, Tl, Pb, Th, and U) in these samples were determined. Trace element contents in solid waste samples showed wide ranges. As compared with the upper continental crust, the solid waste samples are significantly enriched in Se (20x) and Tl (12x) and are moderately enriched in F, As, Mo, Sn, Sb, Hg, Th, and U (2-5x). The solid waste samples are depleted in V, Cr, Mn, Co, Ni, Cu, and Zn. The solid waste samples are enriched in F, V, Mn, Cr, Co, Ni, Cu, Zn, Sb, Th, and U as compared with the Shanxi coals. Most trace elements are higher in the clinker than in the unburnt solid waste except F, Sn, and Hg. Trace element abundances are related to the ash content and composition of the samples. The content of F is negatively correlated with the ash content, while Pb is positively correlated with the ash. The concentrations of As, Mn, Zn, and Cd are highly positively correlated with Fe2O3 in the solid waste. The As content increases with increasing sulfur content in the solid waste. The trace element emissions are calculated for mass balance. The emission factors of trace elements during the spontaneous combustion of the gobs are determined and the trace element concentrations in the flue gas from the spontaneous combustion of solid waste are calculated. More than a half of F, Se, Hg and Pb are released to the atmosphere during spontaneous combustion. Some trace element concentrations in flue gas are higher than the national emission standards. Thus, gob piles from coal mining pose a serious environmental problem. ?? 2007 Elsevier B.V. All rights reserved.

Distribution, bioavailability, and leachability of heavy metals in soil particle size fractions of urban soils (northeastern China).

PubMed

Yutong, Zong; Qing, Xiao; Shenggao, Lu

2016-07-01

This study examines the distribution, mobility, and potential environmental risks of heavy metals in various particle size fractions of urban soils. Representative urban topsoils (ten) collected from Anshan, Liaoning (northeastern China), were separated into six particle size fractions and their heavy metal contents (Cr, Cu, Cd, Pb, and Zn) were determined. The bioaccessibility and leachability of heavy metals in particle size fractions were evaluated using the toxicity characteristic leaching procedure (TCLP) and ethylenediaminetetraacetic acid (EDTA) extraction, respectively. The results indicated that the contents of five heavy metals (Cd, Cr, Cu, Pb and Zn) in the size fractions increased with the decrease of particle size. The clay fraction of <2 μm had the highest content of heavy metals, indicating that the clay fraction was polluted by heavy metals more seriously than the other size fractions in urban topsoils. Cr also concentrated in the coarse fraction of 2000-1000 μm, indicating a lithogenic contribution. However, the dominant size fraction responsible for heavy metal accumulation appeared to belong to particle fraction of 50-2 μm. The lowest distribution factors (DFs) of heavy metals were recorded in the 2000- to 1000-μm size fraction, while the highest in the clay fraction. The DFs of heavy metals in the clay fraction followed Zn (3.22) > Cu (2.84) > Pb (2.61) > Cr (2.19) > Cd (2.05). The enrichment factor suggested that the enrichment degree of heavy metal increased with the decrease of the particle size, especially for Cd and Zn. The TCLP- and EDTA-extractable concentrations of heavy metals in the clay fraction were relatively higher than those in coarse particles. Cd bioavailability was higher in the clay fraction than in other fractions or whole soils. In contrast, Cr exhibits similar bioaccessibilities in the six size fractions of soils. The results suggested that fine particles were the main sources of potentially toxic metals in urban soils. The variation of heavy metals in various size fractions should be taken into account in environment assessments.

Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe.

PubMed

Cutillas-Barreiro, Laura; Pérez-Rodríguez, Paula; Gómez-Armesto, Antía; Fernández-Sanjurjo, María José; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino; Arias-Estévez, Manuel; Nóvoa-Muñoz, Juan Carlos

2016-08-15

We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10-144µg kg(-1), reaching up to 41 and 145mgkg(-1) for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation on the oxidation behavior of AlCrVxN thin films by means of synchrotron radiation and influence on the high temperature friction

NASA Astrophysics Data System (ADS)

Tillmann, Wolfgang; Kokalj, David; Stangier, Dominic; Paulus, Michael; Sternemann, Christian; Tolan, Metin

2018-01-01

Friction minimization is an important topic which is pursued in research and industry. In addition to the use of lubricants, friction-reducing oxide phases can be utilized which occur during. These oxides are called Magnéli phases and especially vanadium oxides exhibit good friction reducing properties. Thereby, the lubrication effect can be traced back to oxygen deficiencies. AlCrN thin films are being used as coatings for tools which have to withstand high temperatures. A further improvement of AlCrN thin films concerning their friction properties is possible by incorporation of vanadium. This study analyzes the temperature dependent oxidation behavior of magnetron sputtered AlCrVN thin films with different vanadium contents up to 13.5 at.-% by means of X-ray diffraction and X-ray absorption near-edge spectroscopy. Up to 400 °C the coatings show no oxidation. A higher temperature of 700 °C leads to an oxidation and formation of Magnéli phases of the coatings with vanadium contents above 10.7 at.-%. Friction coefficients, measured by ball-on-disk test are correlated with the oxide formation in order to figure out the effect of vanadium oxides. At 700 °C a decrease of the friction coefficient with increasing vanadium content can be observed, due to the formation of VO2, V2O3 and the Magnéli phase V4O7.

Chemopreventive properties of raisins originating from Greece in colon cancer cells.

PubMed

Kountouri, Aggeliki M; Gioxari, Aristea; Karvela, Evangelia; Kaliora, Andriana C; Karvelas, Michalis; Karathanos, Vaios T

2013-02-26

Colorectal cancer is one of the major causes of cancer-related mortality in humans in both developed and developing countries. Dietary patterns influence the risk of colon cancer development, while plant-derived foods have gained great interest, due to the high content of antioxidants. Corinthian raisins (Currants, CR) and Sultanas (S) (Vitis vinifera L., Vitaceae) are dried vine fruits produced in Greece with many culinary uses in both the Mediterranean and the Western nutrition. In the present study, we investigated the effects of CR and S on human colon cancer cells. Methanol extracts of CR and S were used at different concentrations. The total polyphenol content and anti-radical activity were measured by Folin-Ciocalteu and DPPH, respectively. Antioxidant, anti-inflammatory and anti-proliferative effects on HT29 cell culture were evaluated. All extracts exhibited DPPH˙ scavenging activity in a dose-dependent manner. Both products suppressed cell proliferation, while the levels of glutathione and cyclooxygenase 2 were significantly decreased. A significant reduction in IL-8 levels and NF-kappaB p65 activation was also observed. Both antioxidant and anti-inflammatory effects were dependent on the duration of exposure. Results indicate that the methanol extracts of CR and S exhibit anti-radical activity in vitro, as well as cancer preventive efficacy on colon cancer cells, with S having slightly higher activity. The beneficial properties of these unique dried grapes are attributed to their high content of phenolic compounds.

Influence of boron content on the microstructure and tribological properties of Cr-B-N coatings in water lubrication

NASA Astrophysics Data System (ADS)

Ma, Qiang; Zhou, Fei; Gao, Song; Wu, Zhiwei; Wang, Qianzhi; Chen, Kangmin; Zhou, Zhifeng; Li, Lawrence Kwok-Yan

2016-07-01

Cr-B-N coatings with different boron contents were deposited on Si(1 0 0) wafers and 316 L stainless steels using unbalanced magnetron sputtering system by way of adjusting the CrB2 target currents. The microstructure and mechanical properties of Cr-B-N coatings were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), white light interferometric three dimensional profilometer and nano-indentation tester, respectively. The tribological properties of Cr-B-N/SiC tribopairs in water were studied using ball-on-disk tribometer. The results showed that the Cr-B-N coatings showed a fine nanocomposite structure consisted of CrN nanograins and amorphous BN phase regardless of boron contents, and the typical columnar structure became featureless with increasing the CrB2 target current. The hardness and reduced elastic modulus first increased to 28.9 GPa and 330 GPa at the CrB2 target current of 2 A, and then decreased gradually with further increasing the CrB2 target current to 4 A. As compared with the CrN/SiC tribopairs, the lowest friction coefficient of Cr-B-N/SiC ball tribopairs in water was 0.15, and the wear resistance of Cr-B-N coatings was effectively enhanced.

Effects of Remineralization Agents on Artificial Carious Lesions.

PubMed

Savas, Selcuk; Kucukyilmaz, Ebru; Celik, Esra Uzer

2016-11-15

The purpose of this study was to evaluate the remineralization potentials of different agents on demineralized enamel surfaces. Four hundred and sixty extracted human molars with artificial carious lesions were divided into six groups: (1) control; (2) acidulated phosphate fluoride (APF); (3) Curodont Repair (CR); (4) silver diamine fluoride (SDF); (5) ammonium hexafluorosilicate (SiF); and (6) SiF plus cetylpiridinium chloride (SiF+CPC). They were subdivided according to immersion periods (seven out of 30 days). After demineralization and remineralization procedures, microhardness test (VHN), energy-dispersive X-ray spectroscopy analysis, and confocal laser scanning microscopy evaluation were performed. The data were statistically analyzed. By the 30-day remineralization, the mean differences in VHN values were ranked as follows, in order: (1) CR; (2) APF; (3) SiF; (4) SiF+CPC; (5) SDF; and (6) control (P<0.05). The calcium (Ca) content and calcium/phosphate ratio for all groups were significantly higher after 30 days (P<0.05). The greatest lesion depth changes were observed in the CR, APF, SiF, and SDF groups (P<0.05), while the greatest fluorescence changes were observed in the APF, SiF, and CR groups (P<0.05). The remineralization was most successful in the CR, APF, and SiF groups, with higher values than for those of the other treatments.

Ferti-irrigational impact of sugar mill effluent on agronomical characteristics of Phaseolus vulgaris (L.) in two seasons.

PubMed

Kumar, Vinod; Chopra, A K

2014-11-01

Ferti-irrigation response of 5, 10, 25, 50, 75, and 100 % concentrations of the sugar mill effluent (SME) on French bean (Phaseolus vulgaris L., cv. Annapurna) in the rainy and summer seasons was investigated. The fertigant concentrations produced significant (P < 0.01) changes in the soil parameters, viz., electrical conductivity (EC), pH, organic carbon (OC), sodium (Na(+)), potassium (K(+)), calcium (Ca(2+)), magnesium (Mg(2+)), total Kjeldahl nitrogen (TKN), phosphate (PO4 (3-)), sulfate (SO4 (2-)), ferrous (Fe(2+)), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn), in both seasons. The contents of Cr, Cu, Mn, and Zn except Cd were found to be below the maximum levels permitted for soils in India. The agronomic performance of P. vulgaris was gradually increased at lower concentrations, i.e., from 5 to 25 %, and decreased at higher concentrations, i.e., from 50 to 100 %, of the SME in both seasons when compared to controls. The accumulations of heavy metals were increased in the soil and P. vulgaris from 5 to 100 % concentrations of the SME in both seasons. The contents of Cu, Mn, and Zn except Cd and Cr were noted under the permissible limit of Food and Agriculture Organization (FAO)/World Health Organization (WHO) standards. Most contents of biochemical components like crude proteins, crude fiber, and total carbohydrates were found with 25 % concentration of the SME in both seasons. The contamination factor (Cf) of various metals was in the order of Cd > Cr > Zn > Mn > Cu for soil and Mn > Zn > Cu > Cr > Cd for P. vulgaris in both seasons after fertigation with SME. Therefore, the SME can be used to improve the soil fertility and yield of P. vulgaris after appropriate dilution.

Heavy metal accumulation and health risk assessment in soil-wheat system under different nitrogen levels.

PubMed

Zhang, Yang; Yin, Changbin; Cao, Suzhen; Cheng, Leilei; Wu, Guosheng; Guo, Jianbiao

2018-05-01

Heavy metal(loid)s (HMs) in organic fertilizer have become a primary source of HMs pollution of farmlands, which could cause deleterious health effects in people exposed through soil-plant systems via multi-pathways. This study investigated China's main grain production area (Henan Province) to evaluate the accumulation and transport characteristics of HMs (Cr, Mn, Ni, Cu, Zn, As, Cd and Pb) in a soil-wheat system and conduct a health risk assessment for wheat (Triticum aestivum) grain under different nitrogenous fertilizer treatments. The results indicated that the Cr, Cu, As and Cd contents in soil were 56.21-113.66, 13.97-58.72, 5.79-22.62 and 0.04-0.23mg·kg -1 , and the mean contents of Cr and As contents in wheat grains were 0.78±0.31 and 0.49±0.18mg·kg -1 , respectively, which exceeded the corresponding standards. The bio-concentration factor and transfer factor were lowest in response to N-fertilization with N8-N15. Health risk assessment showed that the local population who ingested grain from culture condition of N15 experienced the lowest non-cancer and cancer risks. Among different population groups, HMs posed relatively higher non-cancer and cancer risks to children aged 0-5years. Furthermore, Cr and As exposure was the greatest contributor to Hazard Index (HI), accounting for 74.72-83.11%, while Cr exposure accounted for >90% of the total potential cancer risk. Concluding, this study indicated that, to protect human health, the current application of nitrogenous fertilizer should be controlled to an appropriate level. Copyright © 2017 Elsevier B.V. All rights reserved.

Study of Chromium Oxide Activities in EAF Slags

NASA Astrophysics Data System (ADS)

Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

2016-02-01

The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

Removal of trivalent chromium from aqueous solution by zeolite synthesized from coal fly ash.

PubMed

Wu, Deyi; Sui, Yanming; He, Shengbing; Wang, Xinze; Li, Chunjie; Kong, Hainan

2008-07-15

The capability of 14 zeolites synthesized from different fly ashes (ZFAs) to sequestrate Cr(III) from aqueous solutions was investigated in a batch mode. The influence of pH on the sorption of Cr(III) was examined. ZFAs had a much greater ability than fly ash to remove Cr(III), due to the high cation exchange capacity (CEC) and the high acid neutralizing capacity (ANC) of ZFAs. The mechanism of Cr(III) removal by ZFAs involved ion exchange and precipitation. A high-calcium content in both the fly ashes and ZFAs resulted in a high ANC value and, as a result, a high immobilization capacity for Cr(III). The pH strongly influenced Cr(III) removal by ZFAs. Inside the solubility range, removal of chromium increased with increasing pH. Hydroxysodalite made from a high-calcium fly ash had a higher sorptive capacity for Cr(III) than the NaP1 zeolite from medium- and low-calcium fly ashes. On the other hand, at pH values above the solubility range, the efficiency of chromium removal by the ZFAs approached 100% due to the precipitation of Cr(OH)3 on the sorbent surfaces. It is concluded that ZFAs and high-calcium fly ashes may be promising materials for the purification of Cr(III) from water/wastewater.

Study of road dust magnetic phases as the main carrier of potentially harmful trace elements.

PubMed

Bourliva, Anna; Papadopoulou, Lambrini; Aidona, Elina

2016-05-15

Mineralogical and morphological characteristics and heavy metal content of different fractions (bulk, non-magnetic fraction-NMF and magnetic fraction-MF) of road dusts from the city of Thessaloniki (Northern Greece) were investigated. Main emphasis was given on the magnetic phases extracted from these dusts. High magnetic susceptibility values were presented, whereas the MFs content of road dust samples ranged in 2.2-14.7 wt.%. Thermomagnetic analyses indicated that the dominating magnetic carrier in all road dust samples was magnetite, while the presence of hematite and iron sulphides in the investigated samples cannot be excluded. SEM/EDX analyses identified two groups of ferrimagnetic particles: spherules with various surface morphologies and textures and angular/aggregate particles with elevated heavy metal contents, especially Cr. The road dusts (bulk samples) were dominated by calcium, while the mean concentrations of trace elements decreased in the order Zn > Mn > Cu > Pb > Cr > Ni > V > Sn > As > Sb > Co > Mo > W > Cd. MFs exhibited significantly higher concentrations of trace elements compared to NMFs indicating that these potentially harmful elements (PHEs) are preferentially enriched in the MFs and highly associated with the ferrimagnetic particles. Hazard Index (HI) obtained for both adults and children through exposure to bulk dust samples were lower or close to the safe level (=1). On the contrary, the HIs for the magnetic phases indicated that both children and adults are experiencing potential health risk since HI for Cr was significantly higher than safe level. Cancer risk due to road dust exposure is low. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromium doping effects on structural and dielectric properties of Mn-Zn cobaltites

NASA Astrophysics Data System (ADS)

Yadav, A.; Dar, Mashkoor A.; Choudhary, P.; Shah, P.; Varshney, Dinesh

2016-05-01

The effect of transition metal Cr2+ ion as a dopant of Zn2+ in Mn0.5Zn0.5Co2O4 is investigated. Co-doped Mn0.5Zn0.5-xCrxCo2O4 (x = 0, 0.3 and 0.5) cobaltites were prepared by solid-state reaction route. X-ray powder diffraction (XRD) analysis reveals that the samples prepared are polycrystalline single-phase cubic spinel in structure having a space group Fd3m. An increase in average particle size observed with Cr2+ doping. However other structural parameters such as X-ray density, micro strain and dislocation density shows almost a similar decreasing trend with increase in Cr2+. High value of permittivity ˜105 is observed for the parent Mn0.5Zn0.5Co2O4 and shows a substantial decrease with increase in the Cr2+ doping. Higher doping of Cr2+ also increases the dielectric loss and hence limits its technological importance. At lower frequencies ac conductivity has been found to increase with increase in Cr2+ content.

Trace element contaminants in mineral fertilizers used in Iran.

PubMed

Latifi, Zahra; Jalali, Mohsen

2018-05-25

The application of mineral fertilizers which have contaminants of trace elements may impose concern regarding the entry and toxic accumulation of these elements in agro-ecosystems. In this study, 57 mineral fertilizers (nitrogen, potassium, phosphate, and compound fertilizers) distributed in Iran were analyzed for their contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Fe. The results revealed that the contents of these trace elements varied considerably depending on the type of the element and the fertilizer. Among these elements, Fe displayed the highest average content, whereas Cd showed the lowest. Generally, the trace element contents in P-containing fertilizers were higher than those in nitrogen and potassium fertilizers. The mean values of trace elements (mg kg -1 ) in P-containing fertilizers were 4.0 (Cd), 5.5 (Co), 35.7 (Cr), 24.4 (Cu), 272 (Mn), 14.3 (Ni), 6.0 (Pb), 226 (Zn), and 2532 (Fe). Comparing trace element contents to limit values set by the German Fertilizer Ordinance showed that the mean contents of potentially toxic trace elements, such as Cd and Pb, were lower than their limit values in all groups of fertilizers. On the other hand, while a number of fertilizers contained a high content of some essential trace elements, particularly Fe, they were not labeled as such.

Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part I: undamaged steels

NASA Astrophysics Data System (ADS)

Ogorodnikova, O. V.; Zhou, Z.; Sugiyama, K.; Balden, M.; Gasparyan, Yu.; Efimov, V.

2017-03-01

In this paper, reduced-activation ferritic/martensitic (RAFM) steels including Eurofer (9Cr) and oxide dispersion strengthening (ODS) steels by the addition of Y2O3 particles with different amounts of Cr, namely, (9-16)Cr were exposed to low energy deuterium (D) plasma (~20-200 eV per D) up to a fluence of 2.9  ×  1025 D m-2 in the temperature range from 290 K to 700 K. The depth profile of D in steels was measured up to 8 µm depth by nuclear reaction analysis (NRA) and the total retained amount of D in those materials was determined by thermal desorption spectroscopy (TDS). It was found that the D retention in ODS steels is higher compared to Eurofer due to the much higher density of fine dispersoids and finer grain size. This work shows that in addition to the sintering temperature and time, the type, size and concentration of the doping particles have an enormous effect on the increase in the D retention. The D retention in undamaged ODS steels strongly depends on the Cr content: ODS with 12Cr has a minimum and the D retention in the case of ODS with (14-16)Cr is higher compared to (9-12)Cr. The replacing of Ti by Al in ODS-14Cr steels reduces the D retention. The formation of nano-structure surface roughness enriched in W or Ta due to combination of preferential sputtering of light elements and radiation-induced segregation was observed at incident D ion energy of 200 eV for both Eurofer and ODS steels. Both the surface roughness and the eroded layer enhance with increasing the temperature. The surface modifications result in a reduction of the D retention near the surface due to increasing the desorption flux and can reduce the overall D retention.

Weight Changes and Metabolic Outcomes in Calorie-Restricted Obese Mice Fed High-Fat Diets Containing Corn or Flaxseed Oil: Physiological Role of Sugar Replacement with Polyphenol-Rich Grape.

PubMed

Ansar, Hastimansooreh; Zamaninour, Negar; Djazayery, Abolghassem; Pishva, Hamideh; Vafa, Mohammadreza; Mazaheri Nezhad Fard, Ramin; Dilmaghanian, Aydin; Mirzaei, Khadijeh; Shidfar, Farzad

2017-08-01

Because diet components are important during dieting in obesity treatment, we examined possible beneficial effects of substituting corn oil and sugar with flaxseed oil and grape in calorie-restricted high-fat diets on weight changes as well as improvement in some metabolic markers and related gene expression. Seventy-five C57BL/6J male mice were given free access to a high-fat (36% of energy from fat) diet containing corn oil plus sugar (CO + S). After 11 weeks, 15 mice were sacrificed and another 60 were divided among 4 high-fat diet groups with 30% calorie restriction (CR) for the next 12 weeks. The diets contained corn oil (CO) or flaxseed oil (FO) with sugar (S) or grape (G). Despite CR, a weight loss trend was observed only during the first 4 weeks in all groups. CR did not significantly increase SIRT1 gene expression. Higher liver weight was observed in mice consuming FO (p < 0.05). Proliferator-activated receptor gamma (PPARγ) expression decreased in FO + G-CR significantly and even with a reduction of adiposity and higher adiponectin levels, fasting blood sugar (FBS) was significantly higher than in CO + G-CR. Grape intake increased Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expression and decreased insulin resistance in CO + G-CR. Sugar replacement with polyphenol-rich grape along with CR improved glucose homeostasis, and substituting corn oil with flaxseed oil in obese mice reduced fat mass, but even with no change in adiponectin levels it could not decrease insulin resistance. However, none of the food item combinations facilitated weight reduction in the long-term CR. Therefore, regardless of the total calorie intake, different diet components and fat contents may have unexpected effects on metabolic regulation.

Characterization of the Metabolic and Physiologic Response from Chromium Supplementation in Subjects with Type 2 Diabetes

PubMed Central

Cefalu, William T; Rood, Jennifer; Pinsonat, Patricia; Qin, Jianhua; Sereda, Olga; Levitan, Lilian; Anderson, Richard; Zhang, Xian H; Martin, Julie M; Martin, Corby; Wang, Zhong Q; Newcomer, Bradley

2014-01-01

OBJECTIVE To provide a comprehensive evaluation of chromium (Cr) supplementation on metabolic parameters in a cohort of Type 2 DM subjects representing a wide phenotype range and to evaluate changes in “responders” and “non-responders”. DESIGN After pre-intervention testing to assess glycemia, insulin sensitivity (assessed by euglycemic clamps), Cr status, body composition, subjects were randomized in a double-blind fashion to placebo or 1,000 μg Cr. A sub-study was performed to evaluate 24 hour energy balance/substrate oxidation and myocellular/intra-hepatic lipid content. RESULTS There was not a consistent effect of chromium supplementation to improve insulin action across all phenotypes. Insulin sensitivity was negatively correlated to soleus and tibialis muscle intramyocellular lipids and intra-hepatic lipid content. Myocellular lipids were significantly lower in subjects randomized to Cr. At pre-intervention, “responders”, defined as insulin sensitivity change from baseline > 10%, had significantly lower insulin sensitivity and higher fasting glucose and A1c when compared to placebo and “non-responders”, i.e. insulin sensitivity change from baseline < 10%. Clinical response was significantly correlated (p < 0.001) to the baseline insulin sensitivity, fasting glucose and A1c. There was no difference in Cr status between “responders”, and “non-responders”. CONCLUSIONS Clinical response to chromium is more likely in insulin resistant subjects who have more elevated fasting glucose and A1c levels. Cr may reduce myocellular lipids and enhance insulin sensitivity in subjects with type 2 DM independent of effects on weight or hepatic glucose production. Thus, modulation of lipid metabolism by Cr in peripheral tissues may represent a novel mechanism of action. PMID:20022616

Effects of phosphorus fertilizer and lime on the As, Cr, Pb, and V content of soils and plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodroad, L.L.; Caldwell, A.C.

1979-10-01

The occurrence in fertilizer material of small quantities of chemical elements not essential to plants suggests that the soil may become contaminated with these elements due to the use of fertilizers. Two experimental sites: a Nicollet clay loam fertilized with 0, 1111, 2222, 4444, and 8888 kg/ha of concentrated superphosphate (CSP) and 20.2 metric tons of lime, and a Port Byron silt loam fertilized for 19 years with 99, 73, 82, and 352 kg/ha annually of CSP, calcium metaphosphate, phosphoric acid, and southern rock phosphate, respectively, were sampled to determine if significant amounts of arsenic (As), chromium (Cr), lead (Pb),more » or vanadium (V) had been added from the use of these fertilizer materials. There was no indication of increased As, Cr, Pb, or V from the addition of P fertilizers to either the Nicollet or Port Byron soils. The addition of lime increased the Cr content of the Nicollet soil by approximately 3 ppM, but there was no increase in As, Pb, or V. There was no increase in As, Cr, Pb, or V from addition of CSP in soil samples from below the Ap horizon to a depth of 47.5 cm. Soil samples from a representative Nicollet soil suggest that higher As, Cr, Pb, and V concentrations in the A and B horizons are due to leaching of CaCO/sub 3/ into the C horizon. Corn (Zea mays L.) plant growth and grain yields were similar for all CSP and lime treatments. The results of this study indicate that the use of P fertilizers at the rates presently applied would not add substantially to the natural levels of As, Cr, Pb, and V in the soil.« less

Effect of Cr contents on the diffusion behavior of Te in Ni-based alloy

NASA Astrophysics Data System (ADS)

Jia, Yanyan; Li, Zhefu; Ye, Xiangxi; Liu, Renduo; Leng, Bin; Qiu, Jie; Liu, Min; Li, Zhijun

2017-12-01

The embrittlement of Ni-based structural alloys caused by fission production Te is one of the major challenges for molten salt reactors. It has been reported that solution element Cr can prevent the situation of intergranular cracks caused by Te. However, there is no detailed mechanism explanation on this phenomenon. In this study, the effect of Cr on Te diffusion in Ni-Cr binary system was investigated by diffusion experiments at 800 °C for 100 h. Results show that Te reacts with the alloy mainly forming Ni3Te2, and strip shaped Cr3Te4 is only found on the surface of Ni-15%Cr alloy. According to the discussion of thermodynamic chemical reaction process, Cr3Te4 exhibits the best stability and preferential formation compound in Te/Ni-Cr system as its Gibbs free energy of formation is the lowest. With the increase of Cr content in the alloy, the diffusion depth of Te along grain boundaries significantly decreases. Moreover, the formation process of reaction product and diffusion process are described. The diffusion of Te can be suppressed by high content of Cr in Ni-Cr alloy due to the formation of Cr3Te4 and thus the grain boundary is protected from Te corroding.

Origin discrimination of defatted pork via trace elements profiling, stable isotope ratios analysis, and multivariate statistical techniques.

PubMed

Park, Yu Min; Lee, Cheong Mi; Hong, Joon Ho; Jamila, Nargis; Khan, Naeem; Jung, Jong-Hyun; Jung, Young-Chul; Kim, Kyong Su

2018-09-01

This study verified the origin of 346 defatted Korean and non-Korean pork samples via trace elements profiling, and C and N stable isotope ratios analysis. The analyzed elements were 6 Li, 7 Li, 10 B, 11 B, 51 V , 50 Cr, 52 Cr, 53 Cr, 55 Mn, 58 Ni, 60 Ni, 59 Co, 63 Cu, 65 Cu, 64 Zn, 66 Zn, 69 Ga, 71 Ga, 75 As, 82 Se, 84 Sr, 86 Sr, 87 Sr, 88 Sr, 85 Rb, 94 Mo, 95 Mo, 97 Mo, 107 Ag, 109 Ag, 110 Cd, 111 Cd, 113 Cd, 112 Cd, 114 Cd, 116 Cd, 133 Cs, 206 Pb, 207 Pb, and 208 Pb. Content (mg/kg) of 51 V (0.012), 50 Cr (0.882), 75 As (0.017), 85 Rb (57.7), and 87 Sr (46.3) were high in Korean pork samples whereas 6 Li, 7 Li, 59 Co, 55 Mn, 58 Ni, 84 Sr, 86 Sr, 88 Sr, 111 Cd, and 133 Cs were found higher in non-Korean samples. The results of discriminant analysis showed that the trace elements content and stable isotope ratios were significant for the discrimination of geographical origins with a perfect discrimination rate of 100%. Copyright © 2018 Elsevier Ltd. All rights reserved.

CoxFe1-x oxide coatings on metallic interconnects for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Shen, Fengyu; Lu, Kathy

2016-10-01

In order to improve the performance of Cr-containing steel as an interconnect material for solid oxide fuel cells, CoFe alloy coatings with Co:Fe ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 are deposited by electrodeposition and then oxidized to CoxFe1-x oxide coatings with a thickness of ∼6 μm as protective layers on the interconnect. The area specific resistance of the coated interconnect increases with the Fe content. Higher Co content oxide coatings are more effective in limiting the growth of the chromia scale while all coatings are effective in inhibiting Cr diffusion and evaporation. With the Co0.8Fe0.2 oxide coated interconnect, the electrochemical performance of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode is improved. Only 1.54 atomic percentage of Cr is detected on the surface of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode while no Cr is detected 0.66 μm or more into the cathode. CoxFe1-x oxide coatings are promising candidates for solid oxide fuel cell interconnects with the advantage of using existing cathode species for compatibility and performance enhancement.

Flow analysis of metals in a municipal solid waste management system.

PubMed

Jung, C H; Matsuto, T; Tanaka, N

2006-01-01

This study aimed to identify the metal flow in a municipal solid waste (MSW) management system. Outputs of a resource recovery facility, refuse derived fuel (RDF) production facility, carbonization facility, plastics liquefaction facility, composting facility, and bio-gasification facility were analyzed for metal content and leaching concentration. In terms of metal content, bulky and incombustible waste had the highest values. Char from a carbonization facility, which treats household waste, had a higher metal content than MSW incinerator bottom ash. A leaching test revealed that Cd and Pb in char and Pb in RDF production residue exceeded the Japanese regulatory criteria for landfilling, so special attention should be paid to final disposal of these substances. By multiplying metal content and the generation rate of outputs, the metal content of input waste to each facility was estimated. For most metals except Cr, the total contribution ratio of paper/textile/plastics, bulky waste, and incombustible waste was over 80%. Approximately 30% of Cr originated from plastic packaging. Finally, several MSW management scenarios showed that most metals are transferred to landfills and the leaching potential of metals to the environment is quite small.

[Study on trace elements of lake sediments by ICP-AES and XRF core scanning].

PubMed

Cheng, Ai-Ying; Yu, Jun-Qing; Gao, Chun-Liang; Zhang, Li-Sha; He, Xian-Hu

2013-07-01

It is the first time to study sediment of Toson lake in Qaidam Basin. Trace elements including Cd, Cr, Cu, Zn and Pb in lake sediment were measured by ICP-AES method, studied and optimized from different resolution methods respectively, and finally determined a optimum pretreatment system for sediment of Toson lake, namely, HCl-HNO3-HF-HClO4-H2O2 system in the proportions of 5 : 5 : 5 : 1 : 1 was determined. At the same time, the data measured by XRF core scanning were compared, the use of moisture content correction method was analyzed, and the influence of the moisture content on the scanning method was discussed. The results showed that, compared to the background value, the contents of Cd and Zn were a little higher, the content of Cr, Cu and Pb was within the background value limits. XRF core scanning was controlled by sediment elements as well as water content in sediment to some extent. The results by the two methods showed a significant positive correlation, with the correlation coefficient up to 0.673-0.925, and they have a great comparability.

Flow analysis of metals in a municipal solid waste management system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, C.H.; Matsuto, T.; Tanaka, N.

2006-07-01

This study aimed to identify the metal flow in a municipal solid waste (MSW) management system. Outputs of a resource recovery facility, refuse derived fuel (RDF) production facility, carbonization facility, plastics liquefaction facility, composting facility, and bio-gasification facility were analyzed for metal content and leaching concentration. In terms of metal content, bulky and incombustible waste had the highest values. Char from a carbonization facility, which treats household waste, had a higher metal content than MSW incinerator bottom ash. A leaching test revealed that Cd and Pb in char and Pb in RDF production residue exceeded the Japanese regulatory criteria formore » landfilling, so special attention should be paid to final disposal of these substances. By multiplying metal content and the generation rate of outputs, the metal content of input waste to each facility was estimated. For most metals except Cr, the total contribution ratio of paper/textile/plastics, bulky waste, and incombustible waste was over 80%. Approximately 30% of Cr originated from plastic packaging. Finally, several MSW management scenarios showed that most metals are transferred to landfills and the leaching potential of metals to the environment is quite small.« less

[Study on content of nickel in saliva released from the nickel-chromium and the nickel-chromium-titanium porcelain alloy].

PubMed

Wang, Wen-Jie; Zhang, Tai-Qiang; Wei, Hong

2010-02-01

The purpose of the study was to investigate the content of nickel (Ni) ion in patients' saliva after wearing the porcelain-fused-to nickel-chromium (Ni-Cr) crown or the porcelain-fused-to nickel-chromium-titanium(Ni-Cr-Ti) crown. 50 patients who had one molar or premolar needed repairing were selected and divided into two groups randomly. Patients in one group were fabricated with porcelain-fused-to Ni-Cr crown and the patients in the other group were fabricated with porcelain-fused-to Ni-Cr-Ti crown. Collect the patients' saliva before wearing, 1 week, 3 months, and 6 months after wearing. The content of Ni ion in saliva was detected by inductively coupled plasma mass spectrometry (ICP-MS). The content of Ni ion in both groups increased at the first week, and go back after 6 months. There were no significant differences before wearing, 1 week, 3 months, and 6 months after wearing. There were no significant differences between the two groups. Wearing the porcelain-fused-to Ni-Cr crown or the porcelain-fused-to Ni-Cr-Ti crown has no significant influence on the content of Ni ion in saliva.

Analysis of elements in lake sediment samples by PIXE spectrometry

NASA Astrophysics Data System (ADS)

Chelarescu, E. D.; Radulescu, C.; Stihi, C.; Bretcan, P.; Tanislav, D.; Dulama, I. D.; Stirbescu, R. M.; Teodorescu, S.; Bucurica, I. A.; Andrei, R.; Morarescu, C.

2017-09-01

This work aims to determine the concentrations of several elements (e.g. Pb, Ni, Zn, Mn, Cr, and Fe) from lake sediments, in order to characterize their origin and evolution. Particle Induced X-ray Emission (PIXE) technique using the 3 MV Tandetron™ particle accelerator from National Institute for R&D in Physics and Nuclear Engineering "Horia Hulubei" (IFIN-HH), Magurele-Bucharest, Romania, was applied. Sediment cores from different salt lakes from Romania (i.e. Amara Lake, Caineni Lake, and Movila Miresii Lake) were collected, in August 2015. The content of Pb, Cr, Mn, Fe, and Ni from sediment samples show similarities with other data presented in literature and international regulation. The Zn was the only element with a higher content in all samples (e.g. maximum 401.7-517.3 mg/kg d.w.).

Speciation of Cr and its leachability in coal by-products from spanish coal combustion plants.

PubMed

López-Antón, M Antonia; Díaz-Somoano, Mercedes; Cuesta, Aida Fuente; Riesco, Aida Rubio; Martínez-Tarazona, M Rosa

2008-06-01

This study evaluates the behaviour of total Cr and Cr (VI) during coal combustion in two Spanish power stations. The content and distribution of Cr in the feed coal and combustion wastes was determined and the Cr contents were normalized using enrichment factor indexes. The speciation of Cr in the fly ash fractions from the different hoppers of the electrostatic precipitators was established and the possibility that the Cr (VI) might lixiviate when ashes are disposed of at landfill sites was assessed. Differences in the distribution and behavior of Cr in the two power stations were observed. According to European directive 1999/31/CEE, soluble Cr(VI) in the fly ashes studied would be unlikely to pose an environmental or health risk when the ash is disposed of.

Chromate content versus particle size for aircraft paints.

PubMed

LaPuma, Peter T; Rhodes, Brian S

2002-12-01

Many industries rely on the corrosion inhibiting properties of chromate-containing primer paints to protect metal from oxidation. However, chromate contains hexavalent chromium (Cr(6+)), a known human carcinogen. The concentration of Cr(6+) as a function of paint particle size has important implications to worker health and environmental release from paint facilities. This research examines Cr(6+) content as a function of particle size for three types of aircraft primer paints: solvent-based epoxy-polyamide, water-based epoxy-polyamide, and solvent-based polyurethane. Cascade impactors were used to collect and separate paint particles based on their aerodynamic diameter, from 0.7 to 34.1 microm. The mass of the dry paint collected at each stage was determined and an atomic absorption spectrometer was used to analyze for Cr(6+) content. For all three paints, particles less than 7.0 microm contained disproportionately less Cr(6+) per mass of dry paint than larger particles, and the Cr(6+)concentration decreased substantially as particle size decreased. The smallest particles, 0.7 to 1.0 microm, contained approximately 10% of the Cr(6+) content, per mass of dry paint, compared to particles larger than 7.0 microm. The paint gun settings of air to paint ratio was found to have no influence on the Cr(6+) bias.

Effect of the edaphic factors and metal content in soil on the diversity of Trichoderma spp.

PubMed

Racić, Gordana; Körmöczi, Péter; Kredics, László; Raičević, Vera; Mutavdžić, Beba; Vrvić, Miroslav M; Panković, Dejana

2017-02-01

Influence of edaphic factors and metal content on diversity of Trichoderma species at 14 different soil sampling locations, on two depths, was examined. Forty-one Trichoderma isolates from 14 sampling sites were determined as nine species based on their internal transcribed spacer (ITS) sequences. Our results indicate that weakly alkaline soils are rich sources of Trichoderma strains. Also, higher contents of available K and P are connected with higher Trichoderma diversity. Increased metal content in soil was not inhibiting factor for Trichoderma species occurrence. Relationship between these factors was confirmed by locally weighted sequential smoothing (LOESS) nonparametric smoothing analysis. Trichoderma strain (Szeged Microbiology Collection (SZMC) 22669) from soil with concentrations of Cr and Ni above remediation values should be tested for its potential for bioremediation of these metals in polluted soils.

Photocatalytic CO2 reduction by Cr-substituted Ba2(In2-xCrx)O5·(H2O)δ (0.04 ≤ x ≤ 0.60)

NASA Astrophysics Data System (ADS)

Yoon, Songhak; Gaul, Michael; Sharma, Sitansh; Son, Kwanghyo; Hagemann, Hans; Ziegenbalg, Dirk; Schwingenschlogl, Udo; Widenmeyer, Marc; Weidenkaff, Anke

2018-04-01

Cr-substituted polycrystalline Ba2(In2-xCrx)O5·(H2O)δ powders (0.04 ≤ x ≤ 0.60) were synthesized by solid state reaction to investigate the relation of crystal structure, thermochemical, magnetic, and optical properties. The Cr-substitution results in an unit cell expansion and formation of the higher-symmetric tetragonal phase together with increased oxygen and hydrogen contents. Magnetic property measurements reveal that the diamagnetic pristine Ba2In2O5·(H2O)δ becomes magnetically ordered upon Cr-substitution. By UV-vis spectroscopy a gradual shift of the absorption-edge energy to lower values was observed. Numerical calculations showed that the observed bandgap narrowing was ascribed to the Cr induced states near the Fermi level. The correlation between the changes of crystal chemistry, magnetic, and optical properties of Cr-substituted Ba2(In2-xCrx)O5·(H2O)δ can be explained by the replacement of In by Cr. Consequently, an enhanced photocatalytic CO2 reduction activity was observed with increasing Cr substitution, compatible with the state-of-the-art high surface area TiO2 photocatalyst (P-25).

Effects of chromium nanoparticle dosage on growth, body composition, serum hormones and tissue chromium in Sprague-Dawley rats*

PubMed Central

Zha, Long-ying; Xu, Zi-rong; Wang, Min-qi; Gu, Liang-ying

2007-01-01

This 6-week study was conducted to evaluate the effects of seven different levels of dietary chromium (Cr) (0, 75, 150, 300, 450, 600, and 1 200 ppb Cr) in the form of Cr nanoparticle (CrNano) on growth, body composition, serum hormones and tissue Cr in Sprague-Dawley (SD) rats. Seventy male SD rats (average initial body weight of (83.2±4.4) g) were randomly assigned to seven dietary treatments (n=10). At the end of the trial, body composition was assessed via dual energy X-ray absorptiometry (DEXA). All rats were then sacrificed to collect samples of blood, organs and tissues for determination of serum hormones and tissue Cr contents. The results indicated that lean body mass was significantly increased (P<0.05) due to the addition of 300 and 450 ppb Cr from CrNano. Supplementation of 150, 300, 450, and 600 ppb Cr decreased (P<0.05) percent body fat significantly. Average daily gain was increased (P<0.05) by addition of 75, 150, and 300 ppb Cr and feed efficiency was increased (P<0.05) by supplementation of 75, 300, and 450 ppb Cr. Addition of 300 and 450 ppb Cr decreased (P<0.05) the insulin level in serum greatly. Cr contents in liver and kidney were greatly increased (P<0.05) by the addition of Cr as CrNano in the dosage of from 150 ppb to 1 200 ppb. In addition, Supplementation of 300, 450, and 600 ppb Cr significantly increased (P<0.05) Cr content in the hind leg muscle. These results suggest that supplemental CrNano has beneficial effects on growth performance and body composition, and increases tissue Cr concentration in selected muscles. PMID:17542060

[Distribution and Pollution Assessment of Nutrient and Heavy Metals in Surface Sediments from Lake Gehu in Southern Jiangsu Province, China].

PubMed

Xiong, Chun-hui; Zhagn, Rui-lei; Wu, Xiao-dong; Feng, Li-hui; Wang, Li-qing

2016-03-15

This study investigated the horizontal distribution characteristics of nutrients and heavy metals (Zn, As, Cr, Cu, Ni, Pb, Cd and Hg) in January, 2014, and assessed the potential ecological risk of Lake Gehu. It was found that the average contents of TN and TP were 2,207.94 and 708.62 mg · kg⁻¹ respectively. TN and TP contents of the sediments at the centre were significantly highei than those in the north, while the TN content in the south was also significantly higher than that in the north of Lake Gehu. The average contents of Zn, As, Cr, Cu, Ni, Pb, Cd, Hg were 766.59, 350.66, 307.98, 59.54, 122.67, 168.97, 2.34, 0.41 mg · kg⁻¹, respectively. The content of Cu at the centre was significantly higher than that in the north, and the Zn content at the centre was significantly greater than that in the south of Lake Gehu, however the difference in the content of other heavy metals at these three areas was not significant. Furthermore, the obvious correlation between elements and granularity was only found in the aspect of TP, Cu and Hg. The comprehensive pollution index (PI) indicated that the Lake Gehu was heavily polluted, especially the centre and south areas. The potential ecological risk index (RI) showed that Cd, As and Hg had caused serious pollution in Lake Gehu while the other heavy metals only induced slight or medium pollution. According to the contribution of Cd, As and Hg to RI, it was concluded that the sediments in Lake Gehu were at a serious potential ecological risk.

Phase transitions of doped carbon in CrCN coatings with modified mechanical and tribological properties via filtered cathodic vacuum arc deposition

NASA Astrophysics Data System (ADS)

Guan, J. J.; Wang, H. Q.; Qin, L. Z.; Liao, B.; Liang, H.; Li, B.

2017-04-01

The CrCN coatings were fabricated onto Si (1 1 1) wafers and SUS304 stainless steel plates using filtered cathodic vacuum arc deposition (FCVAD) technique under different flow ratios of N2/C2H2 gas mixture. The morphology, crystalline structure and chemical composition of the coatings were characterized. It was found that the grain size reduce with increasing carbon content, which makes the CrCN coatings refined and smooth. The quasi-one-dimensional carbolite phase was also found in CrN host lattice with C2H2 content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CNx phases as C2H2 content exceeds 20%. Moreover, we examined the mechanical and tribological properties of the CrCN coatings, and the experimental results confirmed that the friction coefficient of the coatings descend to the lowest value as 0.39 with 30% C2H2 content, due to the graphite (sp2 Csbnd C) phase embed in CrN host lattice; while the chromium carbon (Cr3C2) and diamond (sp3 Csbnd C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C2H2 content.

Effect of different Zr contents on properties and microstructure of Cu-Cr-Zr alloys

NASA Astrophysics Data System (ADS)

Jinshui, Chen; Bin, Yang; Junfeng, Wang; Xiangpeng, Xiao; Huiming, Chen; Hang, Wang

2018-02-01

The crystallography and morphology of precipitate particles of Cu-Cr-Zr alloys with varying Zr contents were studied by transmission electron microscopy (TEM) after solution treatments at 950 °C for 1 h and aging treatments at 500 °C for different times ranged from 0.5 h to 24 h. The microhardness and electrical conductivity of Cu-Cr-Zr alloys after various aging process were tested. The results show that the microhardness and electrical conductivity rapidly increased at first, then the microhardness decreased slowly after reaching the peak, while the conductivity continues to increase. Nano-scaled precipitates exhibit two kinds of morphology (coffee bean and ellipse shaped). With increasing Zr content, the Zr-containing precipitation sequence of Cu-Cr-Zr alloys at peak-ageing is Heusler CrCu2Zr → Cu5Zr → Cu4Zr. The Heusler CrCu2Zr phase decomposed into fine and homogeneous Cr and Cu4Zr, resulting in improved alloy properties.

Cr(VI)-contaminated groundwater remediation with simulated permeable reactive barrier (PRB) filled with natural pyrite as reactive material: Environmental factors and effectiveness.

PubMed

Liu, Yuanyuan; Mou, Haiyan; Chen, Liqun; Mirza, Zakaria A; Liu, Li

2015-11-15

Permeable reactive barriers (PRBs) are efficient technologies for in situ remediation of contaminated groundwater, the effectiveness of which greatly depends on the reactive media filled. Natural pyrite is an iron sulfide material with a very low content of iron and sulfur, and a mining waste which is a potential material for Cr(VI) immobilization. In this study, we conducted a series of batch tests to research the effects of typical environmental factors on Cr(VI) removal and also simulated PRB filled with natural pyrite to investigate its effectiveness, in order to find a both environmentally and economically fine method for groundwater remediation. Batch tests showed that pH had the significant impact on Cr(VI) removal with an apparently higher efficiency under acidic conditions, and dissolved oxygen (DO) would inhibit Cr(VI) reduction; a relatively high initial Cr(VI) concentration would decrease the rate of Cr(VI) sorption; ionic strength and natural organic matter resulted in no significant effects on Cr(VI) removal. Column tests demonstrated that the simulated PRB with natural pyrite as the reactive media was considerably effective for removing Cr(VI) from groundwater, with a sorption capability of 0.6222 mg Cr per gram of natural pyrite at an initial Cr(VI) concentration of 10mg/L at pH 5.5 in an anoxic environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiple episodes of partial melting, depletion, metasomatism and enrichment processes recorded in the heterogeneous upper mantle sequence of the Neotethyan Eldivan ophiolite, Turkey

NASA Astrophysics Data System (ADS)

Uysal, Ibrahim; Ersoy, E. Yalçın; Dilek, Yildirim; Kapsiotis, Argyrios; Sarıfakıoğlu, Ender

2016-03-01

The Eldivan ophiolite along the Izmir-Ankara-Erzincan suture zone in north-central Anatolia represents a remnant of the Neotethyan oceanic lithosphere. Its upper mantle peridotites include three lithologically and compositionally distinct units: clinopyroxene (cpx)-harzburgite and lherzolite (Group-1), depleted harzburgite (Group-2), and dunite (Group-3). Relics of primary olivine and pyroxene occur in the less refractory harzburgites, and fresh chromian spinel (Cr-spinel) is ubiquitous in all peridotites. The Eldivan peridotites reflect a petrogenetic history evolving from relatively fertile (lherzolite and cpx-harzburgite) toward more depleted (dunite) compositions through time, as indicated by (i) a progressive decrease in the modal cpx distribution, (ii) a progressive increase in the Cr#s [Cr / (Cr + Al)] of Cr-spinel (0.15-0.78), and (iii) an increased depletion in the whole-rock abundances of some magmaphile major oxides (Al2O3, CaO, SiO2 and TiO2) and incompatible trace elements (Zn, Sc, V and Y). The primitive mantle-normalized REE patterns of the Group-1 and some of the Group-2 peridotites display LREE depletions. Higher YbN and lower SmN/YbN ratios of these rocks are compatible with their formation after relatively low degrees (9-25%) of open-system dynamic melting (OSDM) of a Depleted Mid-ocean ridge Mantle (DMM) source, which was then fluxed with small volumes of oceanic mantle-derived melt [fluxing ratio (β): 0.7-1.2%]. Accessory Cr-spinel compositions (Cr# = 015-0.53) of these rocks are consistent with their origin as residual peridotites beneath a mid-ocean ridge axis. Part of the Group-2 harzburgites exhibit lower YbN and higher SmN/YbN ratios, LREE-enriched REE patterns, and higher Cr-spinel Cr#s ranging between 0.54 and 0.61. Trace element compositions of these peridotites can be modeled by approximately 15% OSDM of a previously 17% depleted DMM, which was then fluxed (β: 0.4%) with subduction-influenced melt. The Group-3 dunite samples contain Cr-spinel with elevated Cr#s (0.73-0.78) and low-TiO2 contents (< 0.13 wt.%), implying higher degrees of melting (21-24%) of an already depleted DMM that was triggered by infiltration of low-Ti boninite melt with fluxing rates of 0.4-4.0%. The existence of interstitial, idiomorphic Cr-spinel (high Cr# and low Ti) in the Group-3 dunites is consistent with this interpretation. The occurrence of both MOR- and SSZ-type peridotites in the Eldivan ophiolite suggests that its heterogeneous upper mantle was produced as a result of different partial melting and melt-rock reaction processes in different tectonic settings within the Neotethyan realm.

[Pollution and Potential Ecology Risk Evaluation of Heavy Metals in River Water, Top Sediments on Bed and Soils Along Banks of Bortala River, Northwest China].

PubMed

Zhang, Zhao-yong; Abuduwaili, Jilili; Jiang, Feng-qing

2015-07-01

This paper focuses on the sources, pollution status and potential ecology risks of heavy metals (Cr, Cu, Hg, As, Cd, Pb, and Zn) in the surface water, top sediment of river bed and soil along banks of Bortala River, which locates in the oasis region of Xinjiang, northwest China. Results showed that: (1) As a whole, contents of 7 tested heavy metals of Bortala River were low, while the maximum values of Hg, Cd, Pb, and Cr in the river water were significantly higher than those of Secondary Category of the Surface Water Quality Standards of People's Republic of China (GB 3838-2002) and Drinking Water Guideline from WHO. Analysis showed that the heavy metals contents of top sediment on river bed and soils along river banks were significantly higher than those of the river water. (Correlation analysis and enrichment factor (EF) calculation showed that in the river water, top sediment on river bed and soils along river banks, Hg, Cd, Pb, and Cr mainly originated from industrial emissions, urban and rural anthropogenic activities, transportation and agricultural production activities; While Cu, Zn, and As mainly originated from natural geological background and soil parent materials. (3) Pollution assessment showed that in three matrices, the single factor pollution index(Pi) and the integrated pollution index (Pz) of 7 heavy metals were all lower than 1, and they all belonged to safe and clean levels. (4) Potential ecology risk evaluation showed that as a whole the single factor potential ecological risk (Eir) and the integrated potential ecology risks (RI) of 7 heavy metals were relatively low, and would not cause threats to the health of water and soil environment of river basin, while the potential ecology risks of Cd, Hg, Pb, and Cr were significantly higher than those of other heavy metals.

Atomistic simulations of stainless steels: a many-body potential for the Fe-Cr-C system.

PubMed

Henriksson, K O E; Björkas, C; Nordlund, K

2013-11-06

Stainless steels found in real-world applications usually have some C content in the base Fe-Cr alloy, resulting in hard and dislocation-pinning carbides-Fe3C (cementite) and Cr23C6-being present in the finished steel product. The higher complexity of the steel microstructure has implications, for example, for the elastic properties and the evolution of defects such as Frenkel pairs and dislocations. This makes it necessary to re-evaluate the effects of basic radiation phenomena and not simply to rely on results obtained from purely metallic Fe-Cr alloys. In this report, an analytical interatomic potential parameterization in the Abell-Brenner-Tersoff form for the entire Fe-Cr-C system is presented to enable such calculations. The potential reproduces, for example, the lattice parameter(s), formation energies and elastic properties of the principal Fe and Cr carbides (Fe3C, Fe5C2, Fe7C3, Cr3C2, Cr7C3, Cr23C6), the Fe-Cr mixing energy curve, formation energies of simple C point defects in Fe and Cr, and the martensite lattice anisotropy, with fair to excellent agreement with empirical results. Tests of the predictive power of the potential show, for example, that Fe-Cr nanowires and bulk samples become elastically stiffer with increasing Cr and C concentrations. High-concentration nanowires also fracture at shorter relative elongations than wires made of pure Fe. Also, tests with Fe3C inclusions show that these act as obstacles for edge dislocations moving through otherwise pure Fe.

Atomistic simulations of stainless steels: a many-body potential for the Fe-Cr-C system

NASA Astrophysics Data System (ADS)

Henriksson, K. O. E.; Björkas, C.; Nordlund, K.

2013-11-01

Stainless steels found in real-world applications usually have some C content in the base Fe-Cr alloy, resulting in hard and dislocation-pinning carbides—Fe3C (cementite) and Cr23C6—being present in the finished steel product. The higher complexity of the steel microstructure has implications, for example, for the elastic properties and the evolution of defects such as Frenkel pairs and dislocations. This makes it necessary to re-evaluate the effects of basic radiation phenomena and not simply to rely on results obtained from purely metallic Fe-Cr alloys. In this report, an analytical interatomic potential parameterization in the Abell-Brenner-Tersoff form for the entire Fe-Cr-C system is presented to enable such calculations. The potential reproduces, for example, the lattice parameter(s), formation energies and elastic properties of the principal Fe and Cr carbides (Fe3C, Fe5C2, Fe7C3, Cr3C2, Cr7C3, Cr23C6), the Fe-Cr mixing energy curve, formation energies of simple C point defects in Fe and Cr, and the martensite lattice anisotropy, with fair to excellent agreement with empirical results. Tests of the predictive power of the potential show, for example, that Fe-Cr nanowires and bulk samples become elastically stiffer with increasing Cr and C concentrations. High-concentration nanowires also fracture at shorter relative elongations than wires made of pure Fe. Also, tests with Fe3C inclusions show that these act as obstacles for edge dislocations moving through otherwise pure Fe.

Effect of Si Content on Oxide Formation on Surface of Molten Fe-Cr-C Alloy Bath During Oxygen Top Blowing

NASA Astrophysics Data System (ADS)

Mihara, Ryosuke; Gao, Xu; Kim, Sun-joong; Ueda, Shigeru; Shibata, Hiroyuki; Seok, Min Oh; Kitamura, Shin-ya

2018-02-01

Using a direct observation experimental method, the oxide formation behavior on the surface of Fe-Cr-5 mass pct C-Si alloy baths during decarburization by a top-blown Ar-O2 mixture was studied. The effects of the initial Si and Cr content of the alloy, temperature, and oxygen feed ratio on oxide formation were investigated. The results showed that, for alloys without Si, oxide particles, unstable oxide films, and stable oxide films formed sequentially. The presence of Si in the alloy changed the formation behavior of stable oxide film, and increased the crucial C content when stable oxide film started to form. Increasing the temperature, decreasing the initial Cr content, and increasing the ratio of the diluting gas decreased the critical C content at which a stable oxide film started to form. In addition, the P CO and a_{{{Cr}2 {O}3 }} values at which oxides started to form were estimated using Hilty's equation and the equilibrium relation to understand the formation conditions and the role of each parameter in oxide formation.

Hair biomonitoring and health status of a general population exposed to Nickel.

PubMed

Sazakli, Eleni; Leotsinidis, Michalis

2017-09-01

An epidemiological cross-sectional study was conducted in a Greek population, being orally exposed to Ni via food consumption, in order to investigate possible health effects and to evaluate hair Ni concentration as a biomarker of exposure. The study population consisted of 139 men and 155 women, aged 25-69. Socio-demographics, lifestyle, dietary habits, occupational and medical history data were recorded through a personal interview. Hematological and biochemical examinations were conducted in blood specimens. Metals - Ni, Cr, Cd, Pb, Hg, Cu and Zn - were determined in hair samples. Women were characterized by higher Ni and Cu hair concentrations, while men by higher Cr and Hg. Factors affecting hair metal concentrations were identified to be dietary habits, consumption of local crops, occupation and smoking. Hair element content in the study population was comparable to the "reference ranges" reported in Europe, except for Ni, found higher in a fraction of our population. Men in the upper quartile of hair Ni distribution are at higher risk for abnormal high cholesterol, LDL, albumin and calcium, with odds ratios (OR) varying between 3.5 and 6.2. Accordingly, high hair Ni content in women is associated with abnormal glucose (OR=3.9), triglycerides (OR=3.1) and low abnormal sodium (OR=4.3). The study provides evidence of the suitability of hair analysis in assessing environmental exposure to Ni and supports the use of hair Ni content as a valuable and relatively inexpensive tool of biomonitoring, to identify people at risk for certain biochemical alterations. Copyright © 2017 Elsevier GmbH. All rights reserved.

Atmosphere

NASA Astrophysics Data System (ADS)

Ghosh, D.; Mitra, S. K.

2014-05-01

This paper investigates the high-temperature corrosion behavior of microstructurally different regions of the weldment of 9 Cr-1 Mo steel used in thermal power plant boiler in SO2 + O2 environment. The weldment is produced by tungsten inert gas welding method, and the different regions of the weldment (weld metal, heat-affected zone, and base metal) are exposed in SO2 + O2 (ratio 2:1) environment at 973 K for 120 h. The reaction kinetics and corrosion growth rate of different regions of weldment in isothermal condition are evaluated. The post corroded scales of the different specimens are studied in SEM, EDS, and XRD. The results indicate that the weld metal shows higher corrosion rate followed by HAZ and base metal. The higher rate of corrosion of weldmetal is mainly attributed to the least protective inner scale of Cr2O3 with minimum Cr Content. This is due to the formation of delta ferrite, which leads to the precipitation of the Cr-based secondary phases and depletes the free Cr from the matrix. The thermal cycles during welding at high temperature are favorable for the formation of delta ferrite. On the other hand, in absence of delta ferrite, the base metal and HAZ regions of the weldment show lower corrosion rate than weld metal. The difference in corrosion rate in the three regions of the weldment is supplemented by post-corroded scale characterizations.

One-step solvothermal synthesis of TiO2-reduced graphene oxide nanocomposites with enhanced visible light photoreduction of Cr(VI)

NASA Astrophysics Data System (ADS)

Shaikh, Aasiya; Mishra, Shailendra Prasad; Mohapatra, Priyabrata; Parida, Smrutiranjan

2017-06-01

Hexavalent chromium, Cr(VI), is a mutagenic and carcinogenic heavy metal environmental pollutant. Photoreduction is one of the remediation methods of the hexavalent chromium Cr(VI), which necessitates design of an efficient catalyst for visible light performance. Here, we report a one-step solvothermal synthesis of TiO2-reduced graphene oxide (TiO2- xRGO) composite catalysts using a mild reducing agent, dimethylformamide (DMF). Nanoscale TiO2 particles in the size range of 4-9 nm were formed on the reduced graphene sheets. The formation of the composite catalysts was accompanied by the appearance of a large fluorescence quenching, which indicates an efficient separation of photogenerated electrons and holes. The composites displayed excellent photoreduction of Cr(VI) in the visible light, which was found to be a function of the weight percentage of RGO in the composite. At the optimum composition of TiO2- xRGO, a maximum removal rate of 96% was recorded, which was higher than that of the pristine TiO2, which showed no appreciable catalytic activity under the same condition. The performance degraded with increasing RGO content in the composite, which can be attributed to the higher electron-hole recombination on the RGO surface. The Cr(VI) photoreduction also exhibited a pH dependence. The highest removal rate was observed in the acidic medium.

Evidence for abscisic acid biosynthesis in Cuscuta reflexa, a parasitic plant lacking neoxanthin.

PubMed

Qin, Xiaoqiong; Yang, Seung Hwan; Kepsel, Andrea C; Schwartz, Steven H; Zeevaart, Jan A D

2008-06-01

Abscisic acid (ABA) is a plant hormone found in all higher plants; it plays an important role in seed dormancy, embryo development, and adaptation to environmental stresses, most notably drought. The regulatory step in ABA synthesis is the cleavage reaction of a 9-cis-epoxy-carotenoid catalyzed by the 9-cis-epoxy-carotenoid dioxygenases (NCEDs). The parasitic angiosperm Cuscuta reflexa lacks neoxanthin, one of the common precursors of ABA in all higher plants. Thus, is C. reflexa capable of synthesizing ABA, or does it acquire ABA from its host plants? Stem tips of C. reflexa were cultured in vitro and found to accumulate ABA in the absence of host plants. This demonstrates that this parasitic plant is capable of synthesizing ABA. Dehydration of detached stem tips caused a big rise in ABA content. During dehydration, 18O was incorporated into ABA from 18O2, indicating that ABA was synthesized de novo in C. reflexa. Two NCED genes, CrNCED1 and CrNCED2, were cloned from C. reflexa. Expression of CrNCEDs was up-regulated significantly by dehydration. In vitro enzyme assays with recombinant CrNCED1 protein showed that the protein is able to cleave both 9-cis-violaxanthin and 9'-cis-neoxanthin to give xanthoxin. Thus, despite the absence of neoxanthin in C. reflexa, the biochemical activity of CrNCED1 is similar to that of NCEDs from other higher plants. These results provide evidence for conservation of the ABA biosynthesis pathway among members of the plant kingdom.

Evidence for Abscisic Acid Biosynthesis in Cuscuta reflexa, a Parasitic Plant Lacking Neoxanthin1[W][OA

PubMed Central

Qin, Xiaoqiong; Yang, Seung Hwan; Kepsel, Andrea C.; Schwartz, Steven H.; Zeevaart, Jan A.D.

2008-01-01

Abscisic acid (ABA) is a plant hormone found in all higher plants; it plays an important role in seed dormancy, embryo development, and adaptation to environmental stresses, most notably drought. The regulatory step in ABA synthesis is the cleavage reaction of a 9-cis-epoxy-carotenoid catalyzed by the 9-cis-epoxy-carotenoid dioxygenases (NCEDs). The parasitic angiosperm Cuscuta reflexa lacks neoxanthin, one of the common precursors of ABA in all higher plants. Thus, is C. reflexa capable of synthesizing ABA, or does it acquire ABA from its host plants? Stem tips of C. reflexa were cultured in vitro and found to accumulate ABA in the absence of host plants. This demonstrates that this parasitic plant is capable of synthesizing ABA. Dehydration of detached stem tips caused a big rise in ABA content. During dehydration, 18O was incorporated into ABA from 18O2, indicating that ABA was synthesized de novo in C. reflexa. Two NCED genes, CrNCED1 and CrNCED2, were cloned from C. reflexa. Expression of CrNCEDs was up-regulated significantly by dehydration. In vitro enzyme assays with recombinant CrNCED1 protein showed that the protein is able to cleave both 9-cis-violaxanthin and 9′-cis-neoxanthin to give xanthoxin. Thus, despite the absence of neoxanthin in C. reflexa, the biochemical activity of CrNCED1 is similar to that of NCEDs from other higher plants. These results provide evidence for conservation of the ABA biosynthesis pathway among members of the plant kingdom. PMID:18441226

Characteristics of biomass ashes from different materials and their ameliorative effects on acid soils.

PubMed

Shi, Renyong; Li, Jiuyu; Jiang, Jun; Mehmood, Khalid; Liu, Yuan; Xu, Renkou; Qian, Wei

2017-05-01

The chemical characteristics, element contents, mineral compositions, and the ameliorative effects on acid soils of five biomass ashes from different materials were analyzed. The chemical properties of the ashes varied depending on the source biomass material. An increase in the concrete shuttering contents in the biomass materials led to higher alkalinity, and higher Ca and Mg levels in biomass ashes, which made them particularly good at ameliorating effects on soil acidity. However, heavy metal contents, such as Cr, Cu, and Zn in the ashes, were relatively high. The incorporation of all ashes increased soil pH, exchangeable base cations, and available phosphorus, but decreased soil exchangeable acidity. The application of the ashes from biomass materials with a high concrete shuttering content increased the soil available heavy metal contents. Therefore, the biomass ashes from wood and crop residues with low concrete contents were the better acid soil amendments. Copyright © 2016. Published by Elsevier B.V.

Physiological mechanisms to cope with Cr(VI) toxicity in lettuce: can lettuce be used in Cr phytoremediation?

PubMed

Dias, Maria Celeste; Moutinho-Pereira, José; Correia, Carlos; Monteiro, Cristina; Araújo, Márcia; Brüggemann, Wolfgang; Santos, Conceição

2016-08-01

This research aims at identifying the main deleterious effects of Cr(VI) on the photosynthetic apparatus and at selecting the most sensitive endpoints related to photosynthesis. To achieve this goal, we used lettuce (Lactuca sativa), a sensible ecotoxicological crop model. Three-week-old plants were exposed to 0, 50, 150 and 200 mg L(-1) of Cr(VI). These concentrations ranged from levels admitted in irrigation waters to values found in several Cr industry effluents and heavily contaminated environments. After 30 days of exposure, plants accumulated Cr preferably in roots and showed nutritional impairment, with decreases of K, Mg, Fe and Zn in both roots and leaves. Cr(VI)-exposed plants showed decreased levels of chlorophyll (Chl) a and anthocyanins, as well as decreased effective quantum yield of photostystem II (ΦPSII) and photochemical Chl fluorescence quenching (qp), but increases in the non-photochemical Chl fluorescence quenching (NPQ) and in the de-epoxidation state (DEP) of the xanthophyll cycle. Net CO2 assimilation rate (P N ) and RuBisCO activity were mostly impaired in the highest Cr(VI) concentration tested. Concerning the final products of photosynthesis, starch content was not affected, while soluble sugar contents increased. These alterations were accompanied by a reduction in protein content and in plant growth. Our results support that endpoints related to the photosynthesis photochemical processes (ΦPSII and the qp) and the content of anthocyanins are sensitive predictors of Cr(VI) toxicity. The advantages of using these parameters as biomarkers for Cr toxicity in plants are discussed. Finally, we report that, despite showing physiological disorders, L. sativa plants survived and accumulated high doses of Cr, and their use in environmental/decontamination studies is open to debate.

The effect of grain boundary chemistry on Intergranular stress corrosion cracking of Ni-Cr-Fe alloys in 50 Pct NaOH at 140 °C

NASA Astrophysics Data System (ADS)

Sung, J. K.; Koch, J.; Angeliu, T.; Was, G. S.

1992-10-01

The role of chromium, carbon, chromium carbides, and phosphorus on the intergranular stress corrosion cracking (IGSCC) resistance of Ni-Cr-Fe alloys in 50 pct NaOH at 140 °C is studied using controlled-purity alloys. The effect of carbon is studied using heats in which the carbon level is varied between 0.002 and 0.063 wt pct while the Cr level is fixed at 16.8 wt pct. The effect of Cr is studied using alloys with Cr concentrations between 5 and 30 wt pct. The effect of grain boundary Cr and C together is studied by heat-treating the nominal alloy composition of Ni-16Cr-9Fe-0.035C, and the effect of P is studied using a high-purity, P-doped alloy and a carbon-containing, P-doped alloy. Constant extension rate tensile (CERT) results show that the crack depth increases with decreasing alloy Cr content and increasing alloy C content. Crack- ing severity also correlates inversely with thermal treatment time at 700 °C, during which the grain boundary Cr content rises and the grain boundary C content falls. Phosphorus is found to have a slightly beneficial effect on IG cracking susceptibility. Potentiodynamic polarization and potentiostatic current decay experiments confirm that Cr depletion or grain boundary C enhances the dissolution at the grain boundary. Results support a film rupture-anodic dissolution model in which Cr depletion or grain boundary C (independently or additively) enhances dissolution of nickel from the grain boundary region and leads to increased IG cracking.

Fundamental factors affecting biomass enzymatic reactivity.

PubMed

Chang, V S; Holtzapple, M T

2000-01-01

Poplar wood was treated with peracetic acid, KOH, and ball milling to produce 147 model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and crystallinity indices (CrIs), respectively. An empirical model was identified that describes the roles of these three properties in enzymatic hydrolysis. Lignin content and CrI have the greatest impact on biomass digestibility, whereas acetyl content has a minor impact. The digestibility of several lime-treated biomass samples agreed with the empirical model. Lime treatment removes all acetyl groups and a moderate amount of lignin and increases CrI slightly; lignin removal is the dominant benefit from lime treatment.

Effects of Cr Content and Surface Finishes on Oxidation Behaviors of Austenitic Fe-Cr-Ni Alloys Exposed in Supercritical Water (SCW)

NASA Astrophysics Data System (ADS)

Xing, Bo

The scope of this work was to characterize the corrosion resistance of candidate austenitic alloys in supercritical water for the use of the fuel cladding material within the Canadian supercritical water-cooled reactor (SCWR) concept. A series of Commercial austenitic stainless steels (SS) and alloys were exposed to supercritical water for different exposure times up to 500 hours. Two surface finishes were applied - a coarse grinding with 120 grit abrasive or polishing with either 1200 grit or 0.05 microm alumina suspension. Gravimetric measurements and electron microscopy techniques were used to evaluate the oxidation behaviors of tested alloys. The superior corrosion resistance of alloy 310S was benefited from a critical Cr content of 25 wt.%. The surface finish played a significant role to vary the oxidation behavior of alloys containing slightly less than the critical Cr content. However, Oxide exfoliation was observed on low Cr content alloys.

Silicon content design of CrSiN films for good anti-corrosion and anti-wear performances in NaOH solution

NASA Astrophysics Data System (ADS)

Wang, Haixin; Ye, Yuwei; Wang, Chunting; Zhang, Guangan; Liu, Wei

2018-06-01

The CrSiN films with different silicon contents were fabricated by medium frequency magnetron sputtering. The 304L stainless steel and Si (1 0 0) wafer were used for substrate specimens. Film plasticity, corrosion and tribological behaviors in 0.1 M NaOH solution were systematically investigated. Results show that the plasticity of CrN film could be improved by the addition of silicon. During the corrosion test, with the increase of silicon content, the corrosion current density exhibited a descending trend and impedance presented a rising trend. The COF and wear rate of as-prepared CrSiN film initially decreased and then increased as the silicon content increased. The CrSiN film with 12.7 at.% Si exhibited the lowest COF of 0.04 and a wear rate of 6.746  ×  10‑8 mm3 Nm‑1 in 0.1 M NaOH solution.

Preferred orientation in Cr- and Co-based thin films and its effects on the read/write performance of the media

NASA Astrophysics Data System (ADS)

Tsai, Hsiao-chu; Lal, Brij B.; Eltoukhy, Atef

1992-04-01

This work investigates the formation of preferred crystallographic orientation (PO) in Cr underlayer as well as CoCrTa and CoCrPtTa thin films and its effects on the recording performance of longitudinal media. The results show that the thin-film media with comparable coercivity but different crystalline PO as measured by x-ray diffraction exhibit significant difference in high-frequency signal amplitude, pulse width, and signal-to-noise ratio. To illustrate the effect of PO on parametric performance, CoCrTa/Cr and CoCrPtTa/Cr media were sputtered on different substrates and/or using special sputtering processes to achieve comparable coercivity but different PO in the films. A PO of Cr(200), which normally occurs on the NiP/Al substrates under adequate sputtering conditions, is found to be the key to obtaining a PO of Co(11.0) in Co-alloy media. The consequence of preferred in-plane c-axis orientation is a higher coercivity and better parametric performance of the medium. The formation of PO in the Cr underlayer is found to be related to the substrate material and the oxygen content in the sputtered films. The nonmetallic canasite substrates tend to promote PO of more stable Cr(110) rather than Cr(200). Consequently, this leads to a PO of out-of-plane c axis on the following Co films. The PO of magnetic layer appears to be an important factor in determining the parametric performance of the media.

Lactobacillus fermentum CRL1446 Ameliorates Oxidative and Metabolic Parameters by Increasing Intestinal Feruloyl Esterase Activity and Modulating Microbiota in Caloric-Restricted Mice

PubMed Central

Russo, Matias; Fabersani, Emanuel; Abeijón-Mukdsi, María C.; Ross, Romina; Fontana, Cecilia; Benítez-Páez, Alfonso; Gauffin-Cano, Paola; Medina, Roxana B.

2016-01-01

The purpose of this study was to determine whether the administration of the feruloyl esterase (FE)-producing strain Lactobacillus fermentum CRL1446 enhances metabolic and oxidative parameters in caloric-restricted (CR) mice. Balb/c male mice were divided into ad libitum fed Group (ALF Group), CR diet Group (CR Group) and CR diet plus L. fermentum Group (CR-Lf Group). CR diet was administered during 45 days and CRL1446 strain was given in the dose of 108 cells/mL/day/mouse. FE activity was determined in intestinal mucosa and content at Day 1, 20 and 45. Triglyceride, total cholesterol, glucose, thiobarbituric acid reactive substances (TBARS) levels and glutathione reductase activity were determined in plasma. Gut microbiota was evaluated by high-throughput sequencing of 16S rRNA gene amplicons. At Day 45, total intestinal FE activity in CR-Lf Group was higher (p = 0.020) than in CR and ALF groups and an improvement in both metabolic (reductions in triglyceride (p = 0.0025), total cholesterol (p = 0.005) and glucose (p < 0.0001) levels) and oxidative (decrease of TBARS levels and increase of plasmatic glutathione reductase activity (p = 0.006)) parameters was observed, compared to ALF Group. CR diet increased abundance of Bacteroidetes and CRL1446 administration increased abundance of Bifidobacterium and Lactobacillus genus. L. fermentun CRL1446 exerted a bifidogenic effect under CR conditions. PMID:27399766

Lactobacillus fermentum CRL1446 Ameliorates Oxidative and Metabolic Parameters by Increasing Intestinal Feruloyl Esterase Activity and Modulating Microbiota in Caloric-Restricted Mice.

PubMed

Russo, Matias; Fabersani, Emanuel; Abeijón-Mukdsi, María C; Ross, Romina; Fontana, Cecilia; Benítez-Páez, Alfonso; Gauffin-Cano, Paola; Medina, Roxana B

2016-07-07

The purpose of this study was to determine whether the administration of the feruloyl esterase (FE)-producing strain Lactobacillus fermentum CRL1446 enhances metabolic and oxidative parameters in caloric-restricted (CR) mice. Balb/c male mice were divided into ad libitum fed Group (ALF Group), CR diet Group (CR Group) and CR diet plus L. fermentum Group (CR-Lf Group). CR diet was administered during 45 days and CRL1446 strain was given in the dose of 10⁸ cells/mL/day/mouse. FE activity was determined in intestinal mucosa and content at Day 1, 20 and 45. Triglyceride, total cholesterol, glucose, thiobarbituric acid reactive substances (TBARS) levels and glutathione reductase activity were determined in plasma. Gut microbiota was evaluated by high-throughput sequencing of 16S rRNA gene amplicons. At Day 45, total intestinal FE activity in CR-Lf Group was higher (p = 0.020) than in CR and ALF groups and an improvement in both metabolic (reductions in triglyceride (p = 0.0025), total cholesterol (p = 0.005) and glucose (p < 0.0001) levels) and oxidative (decrease of TBARS levels and increase of plasmatic glutathione reductase activity (p = 0.006)) parameters was observed, compared to ALF Group. CR diet increased abundance of Bacteroidetes and CRL1446 administration increased abundance of Bifidobacterium and Lactobacillus genus. L. fermentun CRL1446 exerted a bifidogenic effect under CR conditions.

Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

DOE PAGES

Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; ...

2015-07-14

The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition.more » Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.« less

Chromium doping effects on structural and dielectric properties of Mn-Zn cobaltites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yadav, A.; Department of Physics, MEDICAPS Institute of Science and Technology, Pithampur 45331; Dar, Mashkoor A., E-mail: darmashkoor.phst@gmail.com

2016-05-06

The effect of transition metal Cr{sup 2+} ion as a dopant of Zn{sup 2+} in Mn{sub 0.5}Zn{sub 0.5}Co{sub 2}O{sub 4} is investigated. Co-doped Mn{sub 0.5}Zn{sub 0.5-x}Cr{sub x}Co{sub 2}O{sub 4} (x = 0, 0.3 and 0.5) cobaltites were prepared by solid-state reaction route. X-ray powder diffraction (XRD) analysis reveals that the samples prepared are polycrystalline single-phase cubic spinel in structure having a space group Fd3m. An increase in average particle size observed with Cr{sup 2+} doping. However other structural parameters such as X-ray density, micro strain and dislocation density shows almost a similar decreasing trend with increase in Cr{sup 2+}. Highmore » value of permittivity ∼10{sup 5} is observed for the parent Mn{sub 0.5}Zn{sub 0.5}Co{sub 2}O{sub 4} and shows a substantial decrease with increase in the Cr{sup 2+} doping. Higher doping of Cr{sup 2+} also increases the dielectric loss and hence limits its technological importance. At lower frequencies ac conductivity has been found to increase with increase in Cr{sup 2+} content.« less

Synchrotron-based imaging of chromium and  γ-H2AX immunostaining in the duodenum following repeated exposure to Cr(VI) in drinking water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Chad M.; Seiter, Jennifer; Chappell, Mark A.

Current drinking water standards for chromium are for the combined total of both hexavalent and trivalent chromium (Cr(VI) and Cr(III)). However, recent studies have shown that Cr(III) is not carcinogenic to rodents, whereas mice chronically exposed to high levels of Cr(VI) developed duodenal tumors. These findings may suggest the need for environmental standards specific for Cr(VI). Whether the intestinal tumors arose through a mutagenic or non-mutagenic mode of action (MOA) greatly impacts how drinking water standards for Cr(VI) are derived. Herein, X-ray fluorescence (spectro)microscopy (µ-XRF) was used to image the Cr content in the villus and crypt regions of duodenamore » from B6C3F1 mice exposed to 180 mg/l Cr(VI) in drinking water for 13 weeks. DNA damage was also assessed by γ-H2AX immunostaining. Exposure to Cr(VI) induced villus blunting and crypt hyperplasia in the duodenum—the latter evidenced by lengthening of the crypt compartment by ~2-fold with a concomitant 1.5-fold increase in the number of crypt enterocytes. γ-H2AX immunostaining was elevated in villi, but not in the crypt compartment. µ-XRF maps revealed mean Cr levels >30 times higher in duodenal villi than crypt regions; mean Cr levels in crypt regions were only slightly above background signal. Despite the presence of Cr and elevated γ-H2AX immunoreactivity in villi, no aberrant foci indicative of transformation were evident. Lastly, these findings do not support a MOA for intestinal carcinogenesis involving direct Cr-DNA interaction in intestinal stem cells, but rather support a non-mutagenic MOA involving chronic wounding of intestinal villi and crypt cell hyperplasia.« less

Synchrotron-Based Imaging of Chromium and γ-H2AX Immunostaining in the Duodenum Following Repeated Exposure to Cr(VI) in Drinking Water

PubMed Central

Thompson, Chad M.; Seiter, Jennifer; Chappell, Mark A.; Tappero, Ryan V.; Proctor, Deborah M.; Suh, Mina; Wolf, Jeffrey C.; Haws, Laurie C.; Vitale, Rock; Mittal, Liz; Kirman, Christopher R.; Hays, Sean M.; Harris, Mark A.

2015-01-01

Current drinking water standards for chromium are for the combined total of both hexavalent and trivalent chromium (Cr(VI) and Cr(III)). However, recent studies have shown that Cr(III) is not carcinogenic to rodents, whereas mice chronically exposed to high levels of Cr(VI) developed duodenal tumors. These findings may suggest the need for environmental standards specific for Cr(VI). Whether the intestinal tumors arose through a mutagenic or non-mutagenic mode of action (MOA) greatly impacts how drinking water standards for Cr(VI) are derived. Herein, X-ray fluorescence (spectro)microscopy (µ-XRF) was used to image the Cr content in the villus and crypt regions of duodena from B6C3F1 mice exposed to 180 mg/l Cr(VI) in drinking water for 13 weeks. DNA damage was also assessed by γ-H2AX immunostaining. Exposure to Cr(VI) induced villus blunting and crypt hyperplasia in the duodenum—the latter evidenced by lengthening of the crypt compartment by ∼2-fold with a concomitant 1.5-fold increase in the number of crypt enterocytes. γ-H2AX immunostaining was elevated in villi, but not in the crypt compartment. µ-XRF maps revealed mean Cr levels >30 times higher in duodenal villi than crypt regions; mean Cr levels in crypt regions were only slightly above background signal. Despite the presence of Cr and elevated γ-H2AX immunoreactivity in villi, no aberrant foci indicative of transformation were evident. These findings do not support a MOA for intestinal carcinogenesis involving direct Cr-DNA interaction in intestinal stem cells, but rather support a non-mutagenic MOA involving chronic wounding of intestinal villi and crypt cell hyperplasia. PMID:25352572

Synchrotron-based imaging of chromium and  γ-H2AX immunostaining in the duodenum following repeated exposure to Cr(VI) in drinking water

DOE PAGES

Thompson, Chad M.; Seiter, Jennifer; Chappell, Mark A.; ...

2014-10-28

Current drinking water standards for chromium are for the combined total of both hexavalent and trivalent chromium (Cr(VI) and Cr(III)). However, recent studies have shown that Cr(III) is not carcinogenic to rodents, whereas mice chronically exposed to high levels of Cr(VI) developed duodenal tumors. These findings may suggest the need for environmental standards specific for Cr(VI). Whether the intestinal tumors arose through a mutagenic or non-mutagenic mode of action (MOA) greatly impacts how drinking water standards for Cr(VI) are derived. Herein, X-ray fluorescence (spectro)microscopy (µ-XRF) was used to image the Cr content in the villus and crypt regions of duodenamore » from B6C3F1 mice exposed to 180 mg/l Cr(VI) in drinking water for 13 weeks. DNA damage was also assessed by γ-H2AX immunostaining. Exposure to Cr(VI) induced villus blunting and crypt hyperplasia in the duodenum—the latter evidenced by lengthening of the crypt compartment by ~2-fold with a concomitant 1.5-fold increase in the number of crypt enterocytes. γ-H2AX immunostaining was elevated in villi, but not in the crypt compartment. µ-XRF maps revealed mean Cr levels >30 times higher in duodenal villi than crypt regions; mean Cr levels in crypt regions were only slightly above background signal. Despite the presence of Cr and elevated γ-H2AX immunoreactivity in villi, no aberrant foci indicative of transformation were evident. Lastly, these findings do not support a MOA for intestinal carcinogenesis involving direct Cr-DNA interaction in intestinal stem cells, but rather support a non-mutagenic MOA involving chronic wounding of intestinal villi and crypt cell hyperplasia.« less

Effect of Cr doping on the structural, morphological, optical and electrical properties of indium tin oxide films

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2015-03-01

We report on the preparation and characterization of high-purity chromium (0.5-2.5 at.%)-doped indium tin oxide (ITO, In:Sn = 90:10) films deposited by sol-gel-mediated dip coating. The effects of different Cr-doping contents on structural, morphological, optical and electrical properties of the films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and four-point probe methods. XRD showed high phase purity cubic In2O3 and indicated a contraction of the lattice with Cr doping. FESEM micrographs show that grain size decreased with increasing the Cr-doping content. A method to determine chromium species in the sample was developed through the decomposition of the Cr 2 p XPS spectrum in Cr6+ and Cr3+ standard spectra. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum sheet resistance of 4,300 Ω/Sq and an average optical transmittance of 85 % in the visible region with a band gap of 3.421 eV, were achieved for the films doped with Cr-doping content of 2 at.%.

Study on Cr(VI) Leaching from Cement and Cement Composites

PubMed Central

Palascakova, Lenka; Kanuchova, Maria

2018-01-01

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time. PMID:29690550

Study on Cr(VI) Leaching from Cement and Cement Composites.

PubMed

Estokova, Adriana; Palascakova, Lenka; Kanuchova, Maria

2018-04-22

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55⁻80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time.

Controlled Growth of Carbon Nanotubes on Micropatterned Au/Cr Composite Film and Field Emission from Their Arrays

NASA Astrophysics Data System (ADS)

Kamide, Koichi; Araki, Hisashi; Yoshino, Katsumi

2003-12-01

Carbon nanotube (CNT) arrays with a controlled density are prepared on a micropatterned Au/Cr composite film formed on a quartz glass plate by pyrolysis of Ni-phthalocyanine at 800°C. It is clarified from characteristic X-ray analyses for those samples that a catalytic Ni nanoparticle is not contained within the base of the whisker-like CNT in contrast to that of the bamboo-like CNT, suggesting that the growth process of the present novel CNT is incompatible with that of the bamboo-like CNT. In the Au/Cr composite film, both the Cr atomic content of approximately 30% and the presence of the Ni catalyst devoid of a particle-like shape are important factors for the growth of CNTs. Field emission from the novel CNT arrays exhibits a lower turn-on voltage and a higher current density compared with that from the bamboo-like arrays formed on a quartz plate.

CoCrMo alloy vs. UHMWPE Particulate Implant Debris Induces Sex Dependent Aseptic Osteolysis Responses In Vivo using a Murine Model

PubMed Central

Landgraeber, Stefan; Samelko, Lauryn; McAllister, Kyron; Putz, Sebastian; Jacobs, Joshua.J.; Hallab, Nadim James

2018-01-01

Background: The rate of revision for some designs of total hip replacements due to idiopathic aseptic loosening has been reported as higher for women. However, whether this is environmental or inherently sex-related is not clear. Objective: Can particle induced osteolysis be sex dependent? And if so, is this dependent on the type of implant debris (e.g. metal vs polymer)? The objective of this study was to test for material dependent inflammatory osteolysis that may be linked to sex using CoCrMo and implant grade conventional polyethylene (UHMWPE), using an in vivo murine calvaria model. Methods: Healthy 12 week old female and male C57BL/6J mice were treated with UHMWPE (1.0um ECD) or CoCrMo particles (0.9um ECD) or received sham surgery. Bone resorption was assessed by micro-computed tomography, histology and histomorphometry on day 12 post challenge. Results: Female mice that received CoCrMo particles showed significantly more inflammatory osteolysis and bone destruction compared to the females who received UHMWPE implant debris. Moreover, females challenged with CoCrMo particles exhibited 120% more inflammatory bone loss compared to males (p<0.01) challenged with CoCrMo implant debris (but this was not the case for UHMWPE particles). Conclusion: We demonstrated sex-specific differences in the amount of osteolysis resulting from CoCrMo particle challenge. This suggests osteo-immune responses to metal debris are preferentially higher in female compared to male mice, and supports the contention that there may be inherent sex related susceptibility to some types of implant debris. PMID:29785221

Heavy Metals in the Vegetables Collected from Production Sites

PubMed Central

Taghipour, Hassan; Mosaferi, Mohammad

2013-01-01

Background: Contamination of vegetable crops (as an important part of people's diet) with heavy metals is a health concern. Therefore, monitoring levels of heavy metals in vegetables can provide useful information for promoting food safety. The present study was carried out in north-west of Iran (Tabriz) on the content of heavy metals in vegetable crops. Methods: Samples of vegetables including kurrat (n=20) (Allium ampeloprasumssp. Persicum), onion (n=20) (Allium cepa) and tomato (n=18) (Lycopersiconesculentum var. esculentum), were collected from production sites in west of Tabriz and analyzed for presence of Cd, Cr, Cu, Ni, Pb and Zn by atomic absorption spectroscopy (AAS) after extraction by aqua regia method (drying, grounding and acid diges­tion). Results: Mean ± SD (mg/kg DW) concentrations of Cd, Cu, Cr, Ni and Zn were 0.32 ± 0.58, 28.86 ± 28.79, 1.75 ± 2.05, 6.37± 5.61 and 58.01 ± 27.45, respec­tively. Cr, Cu and Zn were present in all the samples and the highest concentra­tions were observed in kurrat (leek). Levels of Cd, Cr and Cu were higher than the acceptable limits. There was significant difference in levels of Cr (P<0.05) and Zn (P<0.001) among the studied vegetables. Positive correlation was observed be­tween Cd:Cu (R=0.659, P<0.001) Cr:Ni (R=0.326, P<0.05) and Cr:Zn (R=0.308, P<0.05).   Conclusion: Level of heavy metals in some of the analyzed vegetables, especially kurrat samples, was higher than the standard levels. Considering the possi­ble health outcomes due to the consumption of contaminated vegetables, it is re­quired to take proper actions for avoiding people's chronic exposure. PMID:24688968

Accumulation rates of airborne heavy metals in wetlands

USGS Publications Warehouse

Souch, C.J.; Filippelli, G.M.; Dollar, N.; Perkins, S.; Mastalerz, Maria

2002-01-01

Accumulation rates of heavy metals (Cd, Cr, Cu, Mn, Pb, and Zn) retained in wetland sediments in northwest Indiana-downwind of the Chicago-Gary-Hammond industrial area-are quantified to assess anthropogenic influences on atmospheric fluxes. Metal concentrations for 22 sediment cores are determined by ICP-AES after ashing and strong acid extraction. Relations between organic content and metal concentrations at depth are used to separate natural and anthropogenic sources. Accumulation rates over the lifetime of the wetlands (???4500 years) have averaged 0.2 (Cd), 1.4 (Cu), 1.7 (Cr), 13.4 (Mn), 4.8 (Pb), and 18.7 (Zn) mg m-2 y-1. Rates for the last 100 years have increased on average by factors of 6 (Cd), 8 (Cu), 10 (Mn), 15 (Pb), and 30 (Zn), remaining effectively constant for Cr. Where the wetlands have been drained, metals have been lost from the sediments, owing to changes in organic content and local hydrochemistry (exposure to acidic rainfall). Sediment-based accumulation rates at the undrained sites are higher, though generally consistent, with measured and modeled atmospheric fluxes documented by short-term studies conducted over the last three decades. The fraction of the total metals in the wetlands estimated to be of anthropogenic origin ranges from approximately 3% for Cr, up to approximately 35% for Pb, and 70% for Zn. This historic legacy of contamination must be considered in land management decisions, particularly when wetlands are drained.

Irradiation-enhanced α' precipitation in model FeCrAl alloys

DOE PAGES

Edmondson, Philip D.; Briggs, Samuel A.; Yamamoto, Yukinori; ...

2016-02-17

We have irradiated the model FeCrAl alloys with varying compositions (Fe(10–18)Cr(10–6)Al at.%) with a neutron at ~ 320 to damage levels of ~ 7 displacements per atom (dpa) to investigate the compositional influence on the formation of irradiation-induced Cr-rich α' precipitates using atom probe tomography. In all alloys, significant number densities of these precipitates were observed. Cluster compositions were investigated and it was found that the average cluster Cr content ranged between 51.1 and 62.5 at.% dependent on initial compositions. Furthermore, this is significantly lower than the Cr-content of α' in binary FeCr alloys. As a result, significant partitioning ofmore » the Al from the α' precipitates was also observed.« less

Methods for determining soluble and insoluble Cr III and Cr VI compounds in welding fumes.

PubMed

Matczak, W; Chmielnicka, J

1989-01-01

An analytical procedure for simultaneous determination of soluble and insoluble Cr III and Cr VI compounds in welding fumes has been proposed. In the welding fume samples collected on a membrane filter, total chromium was determined with atomic absorption spectrophotometry (AAS). Glass filters with collected samples were divided into two parts. In one part of the sample, soluble and insoluble chromium was determined by means of AAS. The separation of soluble chromium III and VI was carried out on diphenylcarbazide resin. In the second part of the sample total chromium VI was determined by means of the colorimetric method with s-diphenylcarbazide. The difference in the results of these determinations allowed the calculation of the content of total Cr III, Cr III insolub. and Cr VI insolub. The results of determining chromium compounds in welding fumes samples collected in the welder's breathing zone and in experimental chambers are also presented in this paper. The content of total chromium in the fumes determined by AAS (from a membrane filtr) and that calculated from the sum of soluble and insoluble chromium (from a glass filter) were concordant and within the limits of the admissible error for the method. Total chromium content in welding fume samples collected individually was found to range from 2.4-4.2%. The percentage of particular chromium compounds as compared to total chromium (100%) amounted: total Cr III--34%, total Cr VI--66%, soluble chromium--66% and in this Cr III--20% and Cr VI--43%, insoluble chromium--34% and in this: Cr III--14% and Cr VI--20%.

Involvement of phosphatidate phosphatase in the biosynthesis of triacylglycerols in Chlamydomonas reinhardtii * #

PubMed Central

Deng, Xiao-dong; Cai, Jia-jia; Fei, Xiao-wen

2013-01-01

Lipid biosynthesis is essential for eukaryotic cells, but the mechanisms of the process in microalgae remain poorly understood. Phosphatidic acid phosphohydrolase or 3-sn-phosphatidate phosphohydrolase (PAP) catalyzes the dephosphorylation of phosphatidic acid to form diacylglycerols and inorganic orthophosphates. This reaction is integral in the synthesis of triacylglycerols. In this study, the mRNA level of the PAP isoform CrPAP2 in a species of Chlamydomonas was found to increase in nitrogen-free conditions. Silencing of the CrPAP2 gene using RNA interference resulted in the decline of lipid content by 2.4%–17.4%. By contrast, over-expression of the CrPAP2 gene resulted in an increase in lipid content by 7.5%–21.8%. These observations indicate that regulation of the CrPAP2 gene can control the lipid content of the algal cells. In vitro CrPAP2 enzyme activity assay indicated that the cloned CrPAP2 gene exhibited biological activities. PMID:24302712

Effect of aluminum contents on sputter deposited CrAlN thin films

NASA Astrophysics Data System (ADS)

Vyas, A.; Zhou, Z. F.; Shen, Y. G.

2018-02-01

Pure CrN and CrAlN films with varied Al concentrations were prepared onto Si(100) substrates by an unbalanced reactive dc-magnetron sputtering system. The crystal structure, chemical states, and microstructure of the films were characterized by X-ray diffraction, X-ray photoelectron microscopy, transmission electron microscopy whereas mechanical properties were determined by nano-indentation measurements. XRD results showed a prominent (200) reflection in both CrN and CrAlN films. Results demonstrate that CrAlN films formed a solid solution and doping of Al atoms replace the Cr atoms affecting the lattice parameter and crystallization of the films. All Al doped films were of B1 NaCl-type structure, demonstrating that CrAlN films primarily crystallized in cubic structure. Microstructural investigation by TEM for a CrAlN film containing Al content of 24.1 at.%, revealed that there exists an amorphous/nanocrystalline domains (grains of about ∼ 11 nm) and hardness increases 22% when compared with pure CrN film.

Sulphur alters chromium (VI) toxicity in Solanum melongena seedlings: Role of sulphur assimilation and sulphur-containing antioxidants.

PubMed

Singh, Madhulika; Kushwaha, Bishwajit Kumar; Singh, Samiksha; Kumar, Vipin; Singh, Vijay Pratap; Prasad, Sheo Mohan

2017-03-01

The present study investigates modulation in hexavalent chromium [Cr(VI) 25 μM] toxicity by sulphur (S; 0.5, 1.0 and 1.5 mM S as low (LS), medium (MS) and high sulphur (HS), respectively) in Solanum melongena (eggplant) seedlings. Biomass accumulation (fresh and dry weights), photosynthetic pigments, photosynthetic oxygen evolution and S content were declined by Cr(VI) toxicity. Furthermore, fluorescence characteristics (JIP-test) were also affected by Cr(VI), but Cr(VI) toxicity on photosystem II photochemistry was ameliorated by HS treatment via reducing damaging effect on PS II reaction centre and its reduction side. Enhanced respiration, Cr content and oxidative biomarkers: superoxide radical, hydrogen peroxide, lipid peroxidation and membrane damage were observed under Cr(VI) stress. Though Cr(VI) enhanced adenosine triphasphate sulfurylase (ATPS) and o-acetylserine(thiol)lyase (OASTL), glutathione-S-transferase (GST), glutathione reductase (GR) and ascorbate peroxidase (APX) activity, and content of total glutathione, cysteine and NP-SH, however, their levels/activity were further enhanced by S being maximum with HS treatment. The results show that Cr(VI) toxicity does increase under LS treatment while HS protected Cr(VI)-induced damaging effects in brinjal seedlings. Under HS treatment, in mitigating Cr(VI) toxicity, S assimilation and its associated metabolites such as cysteine, glutathione and NP-SH play crucial role. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Regulation of organic nucleic acids and serum biochemistry parameters by dietary chromium picolinate supplementation in swine model.

PubMed

Jiajun, Yang; Aiyun, Han; Shanshan, Zheng; Minhong, Zhang

2011-04-01

The relationships between chromium and metabolism are sophisticated. Organic nucleic acids and serum biochemistry parameters are affected by dietary chromium levels. The objective of this work was to study the effect of chromium picolinate (CrPic) supplementation on total DNA and RNA contents, the ratio of RNA/DNA in muscle and in pancreatic tissue, the level of insulin receptor (IR) mRNA and some serum biochemistry parameters in a porcine model. Young animals (48) were assigned randomly into three groups of 16 piglets, fed with three different dietary levels of Cr (common basal feedstuff alone or supplemented with CrPic at a dose of 1.61 μg/g or 3.22 μg/g, which corresponds to 0.2 μg/g and 0.4 μg/g Cr). After 80 days, the animals were sacrificed and skeletal muscle and pancreatic tissues were analyzed to detect differences caused by different levels of dietary Cr. The total content of RNA in muscle was increased significantly (P<0.05) in the CrPic supplemented groups. There was no significant difference between groups in the concentrations of total RNA in the pancreas or DNA in the muscle and pancreatic tissues. The RNA/DNA ratio in pancreas showed no significant change but the ratio was increased significantly (P<0.05) in muscle. There was a slight increase of the mRNA level of IR but there was no significant difference between groups. The content of serum cholesterol and insulin were reduced significantly (P<0.05) in the CrPic-supplemented groups and the content of high-density lipoprotein cholesterol (HDLC) was increased significantly (P<0.05) as the CrPic dose increased. There was a slight (non-significant) reduction of the concentrations of serum triglyceride and low-density lipoprotein cholesterol (LDLC) in the CrPic supplementation groups. Supplementary CrPic caused no significant change of muscular mRNA level of IR in healthy animals. An increased content of RNA in muscle, improved cholesterol metabolism and improved insulin sensitivity were found in these CrPic-treated groups in the porcine model. Copyright © 2011 Elsevier GmbH. All rights reserved.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

PubMed

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Distribution, source identification and health risk assessment of soil heavy metals in urban areas of Isfahan province, Iran

NASA Astrophysics Data System (ADS)

Rastegari Mehr, Meisam; Keshavarzi, Behnam; Moore, Farid; Sharifi, Reza; Lahijanzadeh, Ahmadreza; Kermani, Maryam

2017-08-01

The present study examines some heavy metals (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) contents in urban soils of 23 cities in Isfahan province, central Iran. For this purpose, 83 topsoil samples were collected and analyzed by ICP-MS. Results showed that the concentrations of As, Cd, Cu, Pb and Zn are higher than background values, while Co, Cr and Ni concentrations are close to the background. Compared with heavy metal concentrations in selected cities around the world, As, Cd, Cu, Pb and Zn concentrations in urban soils of Isfahan are relatively enriched. Moreover, natural background concentrations of Co, Cr and Ni in Isfahan province soil are high and the apparent enrichment relative to other major cities of the world is due to this high background contents. Calculated contamination factor (CF) confirmed that As, Cd, Cu, Pb and Zn are extremely enriched in the urban soils. Furthermore, pollution load index (PLI) and Geoaccumulation index (Igeo) highlighted that highly contaminated cities are mostly affected by pollution from traffic, industries and Shahkuh Pb-Zn mine. Based on hazard quotients (HQ), hazard index (HI) and cancer risk (CR) calculated in this study, human health risk (particularly for Pb and Cd) have reached alarming scales. Results from principle component analysis (PCA) and positive matrix factorization (PMF) introduces three sources for soils heavy metals including mine and industries (mainly for Pb, Zn, Cd and As); urban activities (particularly for Cu, Pb and Zn); and geogenic source (Ni, Co and Cr).

Reduction of hexavalent chromium by fasted and fed human gastric fluid. II. Ex vivo gastric reduction modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirman, Christopher R., E-mail: ckirman@summittoxi

To extend previous models of hexavalent chromium [Cr(VI)] reduction by gastric fluid (GF), ex vivo experiments were conducted to address data gaps and limitations identified with respect to (1) GF dilution in the model; (2) reduction of Cr(VI) in fed human GF samples; (3) the number of Cr(VI) reduction pools present in human GF under fed, fasted, and proton pump inhibitor (PPI)-use conditions; and (4) an appropriate form for the pH-dependence of Cr(VI) reduction rate constants. Rates and capacities of Cr(VI) reduction were characterized in gastric contents from fed and fasted volunteers, and from fasted pre-operative patients treated with PPIs.more » Reduction capacities were first estimated over a 4-h reduction period. Once reduction capacity was established, a dual-spike approach was used in speciated isotope dilution mass spectrometry analyses to characterize the concentration-dependence of the 2nd order reduction rate constants. These data, when combined with previously collected data, were well described by a three-pool model (pool 1 = fast reaction with low capacity; pool 2 = slow reaction with higher capacity; pool 3 = very slow reaction with higher capacity) using pH-dependent rate constants characterized by a piecewise, log-linear relationship. These data indicate that human gastric samples, like those collected from rats and mice, contain multiple pools of reducing agents, and low concentrations of Cr(VI) (< 0.7 mg/L) are reduced more rapidly than high concentrations. The data and revised modeling results herein provide improved characterization of Cr(VI) gastric reduction kinetics, critical for Cr(VI) pharmacokinetic modeling and human health risk assessment. - Highlights: • SIDMS allows for measurement of Cr(VI) reduction rate in gastric fluid ex vivo • Human gastric fluid has three reducing pools • Cr(VI) in drinking water at < 0.7 mg/L is rapidly reduced in human gastric fluid • Reduction rate is concentration- and pH-dependent • A refined PK model is used to characterize inter-individual variability in Cr(VI) gastric reduction capacity.« less

Environmental characterisation of sewage sludge/paper ash-based composites in relation to their possible use in civil engineering.

PubMed

Mladenovič, Ana; Hamler, Sandra; Zupančič, Nina

2017-01-01

The environmental acceptability of geotechnical composites made of treated municipal sewage sludge (SwS) and paper ash (PA) after two different curing periods has been investigated. The mineral composition of such composites, including their content of major oxides, is mainly influenced by the PA. The content of potentially toxic elements (PTEs) in the initial materials and in the composites varies considerably. In the SwS the Ba, Cd, Cr, Cu, Hg, Ni and Zn contents are above the legally permitted limits. The PTE content of PA are lower, but still somewhat above the permitted values for Ba and Cu. Mixing these two materials together resulted in a decrease in the PTE, but the Ba, Cu and Zn contents are still too high for agricultural application. However, leachates from composites that had been cured for 28 days are highly alkaline, and the As, Ba, Cd, Cr, Hg, Mo, Ni, Pb and Zn contents in them are well below the permitted values. The Cu contents (2.4 to 5.4 mg/kg) are above the permitted limit for inert material, but inside the range for non-hazardous material. In a leachate of composite which was prepared with fresh PA and a lower PA to SwS ratio, the Cu content was 1.4 mg/kg, since fresh PA is more reactive and therefore has a higher ability to immobilise Cu. Therefore, such mixtures can be utilised for covers and liners for sanitary landfills.

Crack Free Tungsten Carbide Reinforced Ni(Cr) Layers obtained by Laser Cladding

NASA Astrophysics Data System (ADS)

Amado, J. M.; Tobar, M. J.; Yáñez, A.; Amigó, V.; Candel, J. J.

The development of hardfacing coatings has become technologically significant in many industries A common approach is the production of metal matrix composites (MMC) layers. In this work NiCr-WC MMC hardfacing layers are deposited on C25 steel by means of laser cladding. Spheroidal fused tungsten carbides is used as reinforcement phase. Three different NiCr alloys with different Cr content were tested. Optimum conditions to obtain dense, uniform carbide distribution and hardness close to nominal values were defined. The effect of Cr content respect to the microstructure, susceptibility for cracking and the wear rate of the resulting coating will also be discussed.

Enhanced removal of Cr(VI) from aqueous solution by supported ZnO nanoparticles on biochar derived from waste water hyacinth.

PubMed

Yu, Jiangdong; Jiang, Chunyan; Guan, Qingqing; Ning, Ping; Gu, Junjie; Chen, Qiuling; Zhang, Junmin; Miao, Rongrong

2018-03-01

Biochar derived from waste water hyacinth was prepared and modified by ZnO nanoparticles for Cr(VI) removal from aqueous solution with the aim of Cr(VI) removal and management of waste biomass. The effect of carbonization temperature (500-800 °C), ZnO content (10-50 wt%) loaded on biochar and contact time (0.17-14 h) on the Cr(VI) removal were investigated. It was found that higher than 95% removal efficiency of Cr(VI) can be achieved with the biochar loaded 30 wt% ZnO. The adsorption kinetics of the sorbent is consistent with the pseudo-second-order kinetic model and adsorption isotherm follows the Langmuir model with maximum adsorption capacity of 43.48 mg g -1 for Cr(VI). Multiple techniques such as XRD, XPS, SEM, EDX and FT-IR were performed to investigate the possible mechanisms involved in the Cr (VI) adsorption. The results show that there is precipitation between chromium ions and Zn oxide. Furthermore, the ZnO nanoparticles acts as photo-catalyst to generate photo-generated electrons to enhance the reduction of Cr(VI) to Cr(III). The as-prepared ZnO/BC possess good recyclability and the removal ratio remained at about 70% in the fifth cycle, which suggests that both contaminants removal and effective management of water hyacinth can be achieved by the approach. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of the formation of thermochemical laser-induced periodic surface structures on Cr, Ti, Ni and NiCr films under femtosecond irradiation

NASA Astrophysics Data System (ADS)

Dostovalov, A. V.; Korolkov, V. P.; Terentyev, V. S.; Okotrub, K. A.; Dultsev, F. N.; Babin, S. A.

2017-07-01

The formation of femtosecond laser-induced periodic surface structures (LIPSS's) on Cr, Ti, Ni and NiCr films (with different Cr contents) is investigated. It is established that thermochemical LIPSS's with periods of 950, 930 and 980 nm are formed, respectively, on the surfaces of titanium, chromium, and nichrome (with a chromium content of 20%); however, thermochemical LIPSS's are not formed on the surfaces of nickel and nichrome with a low chromium content, although Raman data indicate that oxidation occurs in all cases. A weakly ordered ablated structure with a period of 250-300 nm is found to be formed on oxidised areas of thermochemical LIPSS's in the case of chromium and nichrome (80/20). Experimental data on selective etching of thermochemical LIPSS's on titanium and chromium films are presented.

Determination of mineral contents of wild Boletus edulis mushroom and its edible safety assessment.

PubMed

Su, Jiuyan; Zhang, Ji; Li, Jieqing; Li, Tao; Liu, Honggao; Wang, Yuanzhong

2018-04-06

This study aimed to determine the contents of main mineral elements of wild Boletus edulis and to assess its edible safety, which may provide scientific evidence for the utilization of this species. Fourteen mineral contents (Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Sr, V and Zn) in the caps and stipes of B. edulis as well as the corresponding surface soils collected from nine different geographic regions in Yunnan Province, southwest China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrometer (ICP-AES) after microwave digestion. Measurement data were analyzed using variance and Pearson correlation analysis. Edible safety was evaluated according to the provisionally tolerable weekly intake (PTWI) of heavy metals recommended by United Nations Food and Agriculture Organization and World Health Organization (FAO/WHO). Mineral contents were significantly different with the variance of collection areas. B. edulis showed relative abundant contents of Ca, Fe, Mg and Na, followed by Ba, Cr, Cu, Mn and Zn, and the elements with the lower content less were Cd, Co, Ni, Sr and V. The elements accumulation differed significantly in caps and stipes. Among them, Cd and Zn were bioconcentrated (BCF > 1) while others were bioexcluded (BCF < 1). The mineral contents in B. edulis and its surface soil were positively related, indicating that the elements accumulation level was related to soil background. In addition, from the perspective of food safety, if an adult (60 kg) eats 300 g fresh B. edulis per week, the intake of Cd in most of tested mushrooms were lower than PTWI value whereas the Cd intakes in some other samples were higher than this standard. The results indicated that the main mineral contents in B. edulis were significantly different with respect to geographical distribution, and the Cd intake in a few of regions was higher than the acceptable intakes with a potential risk.

Long-term oxidation of candidate cast iron and stainless steel exhaust system alloys from 650 to 800 °C in air with water vapor

DOE PAGES

Brady, Michael P.; Muralidharan, Govindarajan; Leonard, Donovan .; ...

2014-08-29

Here, the oxidation behavior of SiMo cast iron, Ni-resist D 5S cast iron, cast chromia-forming austenitic stainless steels of varying Cr/Ni content based on CF8C plus, HK, and HP, and a developmental cast alumina-forming austenitic (AFA) stainless steel of interest for diesel exhaust system components were studied for up to 5000 h at 650-800 °C in air with 10% H 2O. At 650 °C, the Ni-resist D5S exhibited moderately better oxidation resistance than did the SiMo cast iron. However, the D5S suffered from oxide scale spallation issues at 700 °C and higher, whereas the oxide scales formed on SiMo castmore » iron remained adherent from 700-800 °C despite oxide scales hundreds of microns thick. The oxidation of the SiMo cast iron exhibited unusual temperature dependence, with periods of slower oxidation kinetics at 750-800 °C compared to 650-700 °C due to continuous silica-rich scale formation at the higher temperatures. The oxidation of the cast chromia-forming austenitics trended with the level of Cr and Ni additions, with small mass losses consistent with Cr oxy-hydroxide volatilization processes for the higher 25Cr/25-35Ni HK and HP type alloys, and transition to rapid Fe-base oxide formation and scale spallation in the lower 19Cr/12Ni CF8C plus type alloy. In contrast, small positive mass changes consistent with protective alumina scale formation were observed for the cast AFA alloy under all conditions studied. Implications of these findings for diesel exhaust system components are discussed.« less

Heavy metal distribution and water quality characterization of water bodies in Louisiana's Lake Pontchartrain Basin, USA.

PubMed

Zhang, Zengqiang; Wang, Jim J; Ali, Amjad; DeLaune, Ronald D

2016-11-01

The seasonal variation in physico-chemical properties, anions, and the heavy metal (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) concentration was evaluated in water from nine different rivers in Lake Pontchartrain Basin, Louisiana, USA. The water quality parameters were compared with toxicity reference values (TRV), US Environmental Protection Agency (USEPA) drinking/aquatic life protection, and WHO standards. Among physico-chemical properties, pH, DO, and turbidity were high during spring, while, EC, temperature, and DOC were high during summer and vice versa. The anion study revealed that the concentrations of F - , Cl - , and NO 3 - were higher during summer and Br - and SO 4 - were higher during spring. Our research findings showed anion concentration decreased in the order of Cl -  > SO 4 -  > NO 3 -  > Br -  > F - , in accordance with the global mean anion concentration. The dissolved heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb) except Zn were higher during spring than summer. None of the rivers showed any Cd pollution for both seasons. Co showed higher concentrations in Amite River, Mississippi River, Industrial Canal, and Lacombe Bayou during summer. The Cr concentration was higher than WHO drinking water standards, implicating water unsuitability for drinking purposes in all the rivers associated with the Lake Pontchartrain Basin. Cu showed no pollution risk for the study area. Mn and Co were similar to concentration in Lacombe Bayou, Liberty Bayou, Blind River, and Industrial Canal. Mn levels were greater than WHO standards for the Tickfaw River, Tangipahoa River, and Blind River in both seasons. Blind River, Tangipahoa River, Tickfaw River, and Amite River will require more monitoring for determining possible Mn pollution. Ni content in river water during both seasons showed low pollution risk. Liberty Bayou and Industrial Canal concentrations were closer to the WHO regulatory standards, indicating possible risk of Pb pollution in these water bodies. The Zn content was near the USEPA aquatic life standards in summer for all water bodies. None of the rivers showed any risk associated with Cd, Co, Cu, and Ni levels but medium to higher risk to aquatic life from Cr and Zn for both seasons for most of the rivers. Metal fractionation revealed the decreasing order of inert > labile > organic. The high inert fraction in the rivers under study reflects the major contribution of natural sources in Lake Pontchartrain Basin. The labile and organic forms of Cd, Cu, Ni, and Zn pose potential higher risk to the aquatic life in the Lake Pontchartrain Basin.

Effects of Cr methionine on glucose metabolism, plasma metabolites, meat lipid peroxidation, and tissue chromium in Mahabadi goat kids.

PubMed

Emami, A; Ganjkhanlou, M; Zali, A

2015-03-01

This study was designed to investigate the effects of chromium methionine (Cr-Met) on glucose metabolism, blood metabolites, meat lipid peroxidation, and tissue chromium (Cr) in Mahabadi goat kids. Thirty-two male kids (16.5 ± 2.8 kg BW, 4-5 months of age) were fed for 90 days in a completely randomized design with four treatments. Treatments were supplemented with 0 (control), 0.5, 1, and 1.5 mg Cr as Cr-Met/animal/daily. Blood samples were collected via heparin tubes from the jugular vein on 0, 21, 42, 63, and 90 days of experiment. On day 70, an intravenous glucose tolerance test (IVGTT) was conducted. At the end of the feeding trial, the kids were slaughtered, and the liver, kidney, and longissimus dorsi (LD) muscle samples were collected. Plasma glucose, insulin, and triglyceride concentrations were decreased by Cr supplementation (P < 0.05). LD muscle malondialdehyde (MDA) decreased, and plasma and tissue Cr contents increased with increasing supplemental Cr levels (P < 0.05). Plasma glucose concentrations at 30 and 60 min after glucose infusion were lower in the kids fed 1.5 mg Cr diet than the kids fed control diet (P < 0.05). The IVGTT indicated that the kids supplemented with 1.5 mg Cr had higher glucose clearance rate (K) and lower glucose half-life (T½; P < 0.05). Glucose area under the response curve (AUC) from 0 to 180 min after glucose infusion was decreased linearly (P < 0.01) by supplemental Cr. The results suggested that supplemental Cr may improve glucose utilization and lipid oxidation of meat in fattening kid.

[Pollution Evaluation and Risk Assessment of Heavy Metals from Atmospheric Deposition in the Parks of Nanjing].

PubMed

Wang, Cheng; Qian, Xin; Li, Hui-ming; Sun, Yi-xuan; Wang, Jin-hua

2016-05-15

Contents of heavy metals involving As, Cd, Cr, Cu, Ni, Pb and Zn from atmospheric deposition in 10 parks of Nanjing were analyzed. The pollution level, ecological risk and health risk were evaluated using Geoaccumulation Index, Potential Ecological Risk Index and the US EPA Health Risk Assessment Model, respectively. The results showed that the pollution levels of heavy metals in Swallow Rock Park, Swallow Rock Park and Mochou Lake Park were higher than the others. Compared to other cities such as Changchun, Wuhan and Beijing, the contents of heavy metals in atmospheric deposition of parks in Nanjing were higher. The evaluation results of Geoaccumulation Index showed that Pb was at moderate pollution level, Zn and Cu were between moderate and serious levels, while Cd was between serious and extreme levels. The ecological risk level of Cd was high. The assessment results of Health Risk Assessment Model indicated that there was no non-carcinogenic risk for all the seven heavy metals. For carcinogenic risk, the risks of Cd, Cr and Ni were all negligible (Risk < 1 x 10⁻⁶), whereas As had carcinogenic risk possibility but was considered to be acceptable (10⁻⁶ < Risk < 10⁻⁴).

Influence of Mn contents in 0Cr18Ni10Ti thin wall stainless steel tube on TIG girth weld quality

NASA Astrophysics Data System (ADS)

Liu, Bo

2017-03-01

Three kinds of cold worked 0Cr18Ni10Ti thin wall stainless steel tubes with the manganese contents of 1.27%, 1.35% and 1.44% and the cold worked 0Cr18Ni10Ti stainless steel end plug with manganese content of 1.35% were used for TIG girth welding in the present investigation. The effect of different manganese contents in stainless steel tube on weld quality was studied. The results showed that under the same welding conditions, the metallographic performance of the girth weld for the thin wall stainless steel tube with the manganese element content 1.44% welded with end plug was the best. Under the appropriate welding conditions, the quality of the girth weld increased with the increase of the manganese content till 1.44%. It was found that in the case of the Mn content of 1.44%, and under the proper welding condition the welding defects, such as welding cracks were effectively avoided, and the qualified weld penetration can be obtained.. It is concluded that the appropriate increase of the manganese content can significantly improve the TIG girth weld quality of the cold worked 0Cr18Ni10Ti stainless steel tube.

Effect of dietary chromium picolinate on growth performance and blood parameters in grass carp fingerling, Ctenopharyngodon idellus.

PubMed

Liu, Tailiang; Wen, Hua; Jiang, Ming; Yuan, Danning; Gao, Pan; Zhao, Yujiang; Wu, Fan; Liu, Wei

2010-09-01

An experiment was conducted to investigate the effect of dietary chromium picolinate supplement on growth and haematology parameters of grass carp, Ctenopharyngodon idellus. Six diets with increasing dietary chromium picolinate levels 0, 0.2, 0.4, 0.8, 1.6 and 3.2 mg kg(-1) were fed to triplicate groups of 20 fish (initial weight of 12.78 +/- 1.16 g, mean +/- SD) in a flow water system for 10 weeks. Fish fed the diet supplemented with 0.8 mg Cr kg(-1) had significantly improved weight gain (WG), feed efficiency ratio (FER), protein efficiency ratio (PER) and protein retention (PR). Fish fed high-chromium diets exhibited lower whole-body crude lipid contents than fish fed low-chromium diets. Liver glycogen concentrations for fish fed the diet with 0.2 mg Cr kg(-1) was the highest (77.67 mg g(-1)). Fish fed the diet supplemented with 1.6 and 3.2 mg Cr kg(-1) had significantly lower liver glycogen concentrations than other groups (P < 0.05). The highest serum insulin concentrations were observed in fish fed the diet supplemented with 0.8 mg Cr kg(-1), but serum insulin concentrations decreased (P < 0.05) when dietary supplementation of chromium was higher than 0.8 mg Cr kg(-1). Cholesterol concentrations decreased in direct proportion to dietary chromium level and achieved the lowest level when the fish were fed the 0.8 mg Cr kg(-1) diet, but increased when the fish were fed the diet with more than 0.8 mg Cr kg(-1) (P < 0.05). Fish fed the diet supplemented with 0.8 mg Cr kg(-1) had higher triglyceride and high-density lipoprotein cholesterol (HDL-C) concentrations compared to other treatments. The results of the present study suggested that chromium picolinate could modify serum carbohydrate and lipid metabolism profile, and that the optimal dietary chromium level was 0.8 mg kg(-1) for grass carp according to growth.

A study on toxic and essential elements in wheat grain from the Republic of Kazakhstan.

PubMed

Tattibayeva, Damira; Nebot, Carolina; Miranda, Jose M; Abuova, Altynai B; Baibatyrov, Torebek A; Kizatova, Maigul Z; Cepeda, Alberto; Franco, Carlos M

2016-03-01

Little information is currently available about the content of different elements in wheat samples from the Republic of Kazakhstan. The concentrations of toxic (As, Cd, Cr, Hg, Pb, and U) and essential (Co, Cu, Fe, Mn, Ni, Se, and Zn) elements in 117 sampled wheat grains from the Republic of Kazakhstan were measured. The results indicated that the mean and maximum concentrations of most investigated elements (As, Cd, Co, Cr, Mn, Se, Pb, and U) were higher in samples collected from southern Kazakhstan. The mean and maximum concentrations of toxic elements such as As, Cd, Hg, and Pb did not exceed levels specified by European, FAO, or Kazakh legislation, although the hazard quotient (HQ) values for Co, Cu, Mn, and Zn were higher than 1 and the hazard index (HI) was higher than 1 for samples collected from all areas of Kazakhstan. This indicates that there should be concern about the potential hazards of the combination of toxic elements in Kazakh wheat.

The environmental consequences of the oil shale utilization in Jordan: The effect of combustion processes

NASA Astrophysics Data System (ADS)

El-Hasan, Tayel

2015-04-01

The geochemical analysis of the upper Cretaceous organic rich oil shale of El-Lajjoun revealed that it contains considerable concentrations of trace element when compared to the average world shale. The aim of this study was to deduce the effect of various combustion processes on the geochemical and mineralogical characteristics of the produced ashes.The oil shale powder samples were burned under Aerobic Combustion Process (ACP) at 700˚C, 850˚C and 1000˚C respectively, beside the anaerobic (pyrolysis) combustion process (PCP) at 600, 650, 700, 750 and 800˚C respectively.The ashes produced from the (ACP) caused almost all major oxides contents to increase with increasing burning temperature, particularly SiO2 and CaO were nearly doubled at temperature 1000 ˚C. Moreover, trace elements showed the same trend where ashes at higher temperatures (i.e. 1000 ˚C) have doubled its contents of trace elements such as Cr, Ni, Zn, Cu and U. This was reflected through enrichment of calcite and quartz beside the anhydrite as the main mineral phases in the ACP ashes. As for the PCP ash show similar trend but relatively with lower concentrations as evident from its lowerEnrichment Factor (EF) values. This might be due to the higher organic matter remained in the PCP ashes compared with ACP ashes. However, PCP is more likely associated with toxic Cd and Asgasses as evident from their lowerconcentrations in the ashes.Moreover, recent results using the synchrotron-based XANES technique confirm that toxic elements are found in higher oxidation state due to ACP. The investigation was concerned on As and Cr. Thechromium in the original shales was in the form of Cr (III) and then it was converted to Cr(VI) in the ashes due of the ACP. Similarly, As (III) the XANES results showed that it was converted into As(V) too. These findingsare alarming and should be taken seriously. Because elements with higher oxidation states became more mobile, thus they can easily leached from the ash tailing into the nearby water resources. The most important species is Cr(VI) because itis easily leachable and very harmful species. It could cause pollution to surface and ground water resources.Therefore, allot of concerns should be paid on the ongoing oil shale utilization enterprises due to its pollution potential.Further investigation regarding the speciation of vanadium and cadmium are on the way.

Heavy Metal Content in Chilean Fish Related to Habitat Use, Tissue Type and River of Origin.

PubMed

Copaja, S V; Pérez, C A; Vega-Retter, C; Véliz, D

2017-12-01

In this study, we analyze the concentration of ten metals in two freshwater fish-the benthic catfish Trichomycterus areolatus and the limnetic silverside Basilichthys microlepidotus-in order to detect possible accumulation differences related to fish habitat (benthic or pelagic), tissue type (gill, liver and muscle), and the river of origin (four different rivers) in central Chile. The MANOVA performed with all variables and metals, revealed independent effects of fish, tissue and river. In the case of the fish factor, Cu, Cr, Mo and Zn showed statistically higher concentrations in catfish compared with silverside for all tissues and in all rivers (p < 0.05). In the case of the tissue factor, Al, Cr, Fe and Mn had statistically higher concentrations in liver and gills than in muscle (p  < 0.05). For the river effect, the analysis showed higher concentrations of Cr, Mn and Pb in the Cogoti river and the lower concentrations in the Recoleta river. These results suggest that not all metals have the same pattern of accumulation; however, some metals tend to accumulate more in readily catfish, probably due to their benthic habit, and in liver and gill tissue, probably as a result of accumulation from food sources and respiration.

Dendrite segregation in Ni3Al-based intermetallic single crystals alloyed with Cr, Mo, W, Ti, Co, and Re

NASA Astrophysics Data System (ADS)

Drozdov, A. A.; Povarova, K. B.; Morozov, A. E.; Antonova, A. V.; Bulakhtina, M. A.; Alad'ev, N. A.

2015-07-01

The character of dendrite segregation in Ni3Al-based intermetallic VKNA-type alloy single crystals with a dendritic-cellular structure is studied. Distribution coefficient k d of an alloying element (AE) in the alloy during solidification k d = c d.a.I/ c 0 ( c 0 is the AE content in the alloy (liquid phase composition), c d.a.I is the AE content in primary dendrite arms of the alloy (in the solid phase)) and segregation coefficient k s = c d.a.I/ c i.d ( c i.d is the AE content in the interdendritic space) have been found. A comparative study of the dendrite segregation parameters in VKNA-nype Ni3Al-based intermetallic alloys and the well-known ZhS36-type nickel superalloy shows that the intermetallic alloys satisfy to the rule deduced for two- and three-component nickel-based superalloys: if an introduced AE increases the melting temperature of the basic metal, we have k d > 1 (Co, W, Re); if it decreases the melting temperature, we have k d < 1 (Al, Ti, Cr, Mo). Dendrite segregation coefficients k s are dependent on the proportion of the AE contents in the alloys. In nickel superalloys, the dendrite segregation of aluminum, tungsten, and rhenium is higher than that in the intermetallic alloys. The dendrite segregation coefficients of tungsten and rhenium is higher by a factor of 1.5-2 than that in the VKNA-type intermetallic alloys with a low content of refractory metals. This can be due to the retardation of diffusion of refractory metals in the solid phase of a nickel superalloy highly alloyed with these elements.

Solute transport and the prediction of breakaway oxidation in gamma + beta Ni-Cr-Al alloys

NASA Technical Reports Server (NTRS)

Nesbitt, J. A.; Heckel, R. W.

1984-01-01

The Al transport and the condition leading to breakaway oxidation during the cyclic oxidation of gamma + beta NiCrAl alloys have been studied. The Al concentration/distance profiles were measured after various cyclic oxidation exposures at 1200 C. It was observed that cyclic oxidation results in a decreasing Al concentration at the oxide/metal interface, maintaining a constant flux of Al to the Al2O3 scale. It was also observed that breakaway oxidation occurs when the Al concentration at the oxide/metal interface approaches zero. A numerical model was developed to simulate the diffusional transport of Al and to predict breakaway oxidation in gamma + beta NiCrAl alloys undergoing cyclic oxidation. In a comparison of two alloys with similar oxide spalling characteristics, the numerical model was shown to predict correctly the onset of breakaway oxidation in the higher Al-content alloy.

[Preparation of electrodeposited Cr-La coating and its spectral properties].

PubMed

Liu, Xiao-zhen; Wang, Gang; Song, Ling-ling; Li, Xin; Zhu, Xu-qiang

2011-07-01

Cr-La coating (dc) and Cr-La coating (pulse) were prepared by electrodeposition method of direct current and pulsating current respectively. The Cr-La coating (dc) and Cr-La coating (pulse) were characterized with ICP-AES, EDAX, XRD and SEM techniques, respectively. Cr-La coating(dc) was amorphous. There were crystalline La and CrC in Cr-La coating (pulse). The microhardness of the Cr-La coating(dc) and Cr-La coating (pulse) were as high as 860.3 and 930.2 HV respectively, which were higher 11.15% and 20.18% higher than that of the Cr coating (774.0 HV). The wear weight losses of Cr-La coating(dc) and Cr-La coating(pulse) were 1.29 and 2.25 times lower than that of Cr coating, respectively. The friction coefficient of Cr coating, Cr-La coating(dc) and Cr-La coating(pulse) were 0. 884, 0. 640 and 0. 648 respectively. The properties of wear weight loss and microhardness of coatings were improved with pulsating current. The wear weight loss and microhardness of Cr-La coating(pulse) were lower 1.75 time lower and higher 8.13% higher than that of the Cr-La coating(dc), respectively.

A study of ignition of metal impregnated carbons: the influence of oxygen content in the activated carbon matrix.

PubMed

van der Merwe, M M; Bandosz, T J

2005-02-01

A study of the reason for the early ignition of coconut-based impregnated carbon in comparison with the peat-based impregnated carbon was conducted. The surface features of carbons were evaluated using various physicochemical methods. The metal analysis of the initial carbon indicated that the content of potassium was higher in the coconut-based carbon. The surface functional group analysis revealed the presence of similar surface species; however, the peat-based carbon was more acidic in its chemical nature. Since the oxygen content was higher in the peat-based carbon, the early ignition of the coconut-based material was attributed to its higher affinity to chemisorb oxygen, which leads to exothermic effects. This conclusion was confirmed by performing oxidation of coconut-based carbon prior to impregnation. This process increased the ignition temperature for Cu/Cr impregnated coconut-based material from 186 to 289 degrees C and for the Cu/Zn/Mo impregnated carbon from 235 to 324 degrees C.

Exposure to hexavalent chromium in welders: Results of the WELDOX II field study.

PubMed

Pesch, Beate; Lehnert, Martin; Weiss, Tobias; Kendzia, Benjamin; Menne, Eleonore; Lotz, Anne; Heinze, Evelyn; Behrens, Thomas; Gabriel, Stefan; Schneider, Wolfgang; Brüning, Thomas

2018-03-12

Exposure to hexavalent chromium (Cr(VI)) has been primarily studied in chromate production. Here, we measured personal exposure to respirable Cr(VI) together with airborne and urinary Cr and Ni in welders to explore levels and associations between various measures of exposure. Shift concentrations of Cr(VI), Cr, and Ni were measured in respirable welding fumes in 50 men who used either gas metal arc welding (GMAW) (n = 24) or tungsten inert gas welding (TIG) (n = 19) as their major technique. Cr and Ni were determined in pre- and post-shift urine samples. Concentrations below the limit of quantification (LOQ) were multiply imputed. Spearman correlation coefficients (rs) were calculated with 95% confidence intervals (CIs) to explore associations between the exposure variables, and regression models were applied to estimate the effect of the parent metal on the urinary concentration. Regarding the respirable Cr(VI), 62% of the measurements were below the LOQ, the 75th percentile was 0.50 µg m-3, and 8 out of 50 (16%) welders exceeded 1 µg m-3. The highest shift concentration that occurred as a result of shielded metal arc welding (SMAW) was 180 µg m-3. The Cr(VI) content in total Cr ranged from 4 to 82% (median 20%), although the concentration correlated with total Cr (rs 0.55, 95% CI 0.46; 0.64). The correlation between Cr(VI) and Ni was weaker (rs 0.42, 95% CI 0.34; 0.51) than that between total Cr and Ni in welding fumes (rs 0.83, 95% CI 0.74; 0.92). Both Cr(VI) and total Cr influenced the urinary Cr concentrations in post-shift samples (P = 0.0008 and P ≤ 0.0001, respectively). The airborne shift exposure was a weaker determinant than the Cr content in pre-shift urine samples, which strongly correlated with post-shift urinary Cr (rs 0.78, 95% CI 0.69; 0.87). The Cr(VI) content in total Cr varied considerably in welding fumes. The majority of welders using GMAW or TIG presented with shift concentrations of respirable Cr(VI) below 1 µg m-3. However, very high Cr(VI) concentrations may occur, for example in SMAW. The urinary concentration of total Cr, cannot be used to precisely determine the shift concentration of respirable Cr(VI) in welders.

Selective Internal Oxidation as a Mechanism for Intergranular Stress Corrosion Cracking of Ni-Cr-Fe Alloys

NASA Astrophysics Data System (ADS)

Capell, Brent M.; Was, Gary S.

2007-06-01

The mechanism of selective internal oxidation (SIO) for intergranular stress corrosion cracking (IGSCC) of nickel-base alloys has been investigated through a series of experiments using high-purity alloys and a steam environment to control the formation of NiO on the surface. Five alloys (Ni-9Fe, Ni-5Cr, Ni-5Cr-9Fe, Ni-16Cr-9Fe, and Ni-30Cr-9Fe) were used to investigate oxidation and intergranular cracking behavior for hydrogen-to-water vapor partial pressure ratios (PPRs) between 0.001 and 0.9. The Ni-9Fe, Ni-5Cr, and Ni-5Cr-9Fe alloys formed a uniform Ni(OH)2 film at PPRs less than 0.09, and the higher chromium alloys formed chromium-rich oxide films over the entire PPR range studied. Corrosion coupon results show that grain boundary oxides extended for significant depths (>150 nm) below the sample surface for all but the highest Cr containing alloy. Constant extension rate tensile (CERT) test results showed that intergranular cracking varied with PPR and cracking was more pronounced at a PPR value where nonprotective Ni(OH)2 was able to form and a link between the nonprotective Ni(OH)2 film and the formation of grain boundary oxides is suggested. The observation of grain boundary oxides in stressed and unstressed samples as well as the influence of alloy content on IG cracking and oxidation support SIO as a mechanism for IGSCC.

[Study on high temperature oxidation of Ni-Cr ceramic alloys. Effects of Cr and Mo].

PubMed

Mizutani, M

1990-03-01

The effects of Cr and Mo addition to Ni-Cr alloys on high temperature oxidation were investigated. The alloys were prepared with the composition of Cr ranging from 5 to 40 wt%. Also 2, 4 and 9 wt% of Mo was added to both Ni-5% Cr and Ni-20% Cr binary alloys. The alloys were heated at 800 degrees C, 900 degrees C and 1000 degrees C for 15 minutes in air, and the weight change after heat treatment was measured by electric automatic balance. The weight change during heating was measured by thermogravimetric measurement (TG). The products after heat treatment were characterized by X-ray diffraction and scanning electron microscopy (SEM). The results are summarized as follows: The Ni-Cr binary alloys were classified into three types of Cr ranging from 5 to 20 wt%, Cr 25% and Cr from 30 wt% to 40 wt% according to the weight gains with oxidation. In the case of the more than 25 wt% Cr content of the Ni-Cr binary alloys, the weight gain was extremely low and the heating temperature effects on the weight change were also small. X-ray diffraction study showed that NiO, NiCr2O4 and Cr2O3 formed on the surface of the Ni-Cr binary alloys whose composition of Cr ranged from 5 to 25 wt%, whereas NiO and NiCr2O4 rarely formed on the Ni-Cr binary alloys whose composition of Cr ranged from 30 to 40 wt%. This suggests that the formation of Cr2O3 prevents the formation of NiO on the alloy with a high Cr content. The weight gain of the Ni-Cr-Mo ternary alloys was smaller than that of the Ni-Cr binary alloys without Mo, and the temperature effects on the weight gain of the Ni-Cr-Mo ternary alloys were different for each Cr content. However, the effect of the amounts of Mo was small. NiO, NiCr2O4, Cr2O3 and MoO2 were identified by X-ray diffraction on the surface of the Ni-Cr-Mo ternary alloys. According to the SEM observation, it seems that NiO was formed at the outermost layer, both NiCr2O4 and Cr2O3 at the inside layer, and MoO2 at the innermost layer. The formation of both NiO and Cr2O3 on the Ni-Cr-Mo ternary alloys was restrained compared with that of the Ni-Cr binary alloys. However, the adhesion of oxides to the Ni-Cr-Mo ternary alloys was lower than that of the Ni-Cr binary alloys.

Selection of Compositions in Ti-Cr-C-Steel, Ti-B, Ti-B-Me Systems and Establishing Synthesis Parameters for Obtaining Product by “SHS-Electrical Rolling”

NASA Astrophysics Data System (ADS)

Aslamazashvili, Zurab; Tavadze, Giorgi; Chikhradze, Mikheil; Namicheishvili, Teimuraz; Melashvili, Zaqaria

2017-12-01

For the production materials by the proposed Self-propagating High-Temperature Synthesis (SHS) - Electric Rolling method, there are no limitations in the length of the material and the width only depends on the length of rolls. The innovation method enables to carry out the process in nonstop regime, which is possible by merging energy consuming SHS method and Electrical Rolling. For realizing the process it is mandatory and sufficient, that initial components, after initiation by thermal pulse, could interaction with the heat emission, which itself ensures the self-propagation of synthesis front in lieu of heat transfer in the whole sample. Just after that process, the rolls instantly start rotation with the set speed to ensure the motion of material. This speed should be equal to the speed of propagation of synthesis front. The synthesized product in hot plastic condition is delivered to the rolls in nonstop regime, simultaneously, providing the current in deformation zone in order to compensate the energy loses. As a result by using the innovation SHS -Electrical Rolling technology we obtain long dimensional metal-ceramic product. In the presented paper optimal compositions of SHS chasms were selected in Ti-Cr-C-Steel, Ti-B and Ti-B-Me systems. For the selection of the compounds the thermodynamic analysis has been carried out which enabled to determine adiabatic temperature of synthesis theoretically and to determine balanced concentrations of synthesized product at synthesis temperature. Thermodynamic analysis also gave possibility to determine optimal compositions of chasms and define the conditions, which are important for correct realization of synthesis process. For obtaining non porous materials and product by SHS-Electrical Rolling, it is necessary to select synthesis and compacting parameters correctly. These parameters are the pressure and the time. In Ti-Cr-C-Steel, Ti-B and Ti-B-Me systems the high quality (nonporous or low porosity <2%) of materials and product is directly depended on the liquid phase content just after the passing of synthesis front in the sample. The more content of liquid phase provides the higher quality of material. The content of liquid phase itself depends on synthesis parameters: speed and temperature of synthesis. The higher the speed and temperature of synthesis we have, higher the content of liquid phase is formed. The speed and the temperature of synthesis depend on the Δρ relative density of sample formed from initial chasm, this mean it depends on the pressure of formation of the sample. The paper describes the results of determination of optimal pressures in Ti-Cr-C-Steel, Ti-B and Ti-B-Me systems. Their values are defined as 50-70 MPa, 180-220 MPa and 45-70 MPa.

Novel Approach for Welding Stainless Steel Using Cr-Free Welding Consumables

DTIC Science & Technology

2004-12-31

Breakdown potential ERP Repassivation potential SS Stainless steel SMAW Shielded metal arc welding GTAW Gas tungsten arc welding PEL Permissible...0.1 M NaCl. 14 4. List of Tables Table 1. Details of GTAW procedure. 7 1 5. Acknowledgements The work in this report was...resistance, filler metals matching or exceeding the chromium (Cr) content of the base metal must be used. The Cr content of Types 304 and 308 stainless

Content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured in modern farm at BLUPPB, Karawang, West Java

NASA Astrophysics Data System (ADS)

Takarina, N. D.; Rahman, A.; Siswanting, T.; Pin, T. J.

2018-03-01

Heavy metal is one of the hazardous substances which often found in shrimp farm. Since this shrimp become mostly favorable food, it is necessary to determine the content of metal in this shrimps. This research was aimed to determine the content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured on the modern farm at BLUPPB, Karawang, West Java. Samples were taken from five farms. During transport, samples were kept in a more relaxed box. Farms used were designed using black plastic as the bottom layer to separate contact with soil. Heavy metal of Cr, Cu, Pb, and Zn on shrimp meat was analyzed using Atomic Absorption Spectrophotometry method. The content of Cr was ranged from 0.06 – 0.38 ppm and Pb were 0.02 – 0.05 ppm. The content of Cu was ranged from 1.89 – 15.25 ppm and Zn were 2.16 – 3.92 ppm. According to government rules and literature, those content were below a threshold which was 0.4 ppm for Cu, 0.5 ppm for Pb, 20 ppm for Cu and 0.2 ppm for Zn.

Myocellular creatine and creatine transporter serine phosphorylation after starvation.

PubMed

Zhao, Chun-Rui; Shang, Lihong; Wang, Weiyang; Jacobs, Danny O

2002-06-01

Myocellular creatine, which is critically important for normal energy metabolism, increases in rat gastrocnemius muscle after starvation via unknown mechanisms. Creatine (Cr) uptake across plasma membranes is governed by a single, specific transporter (CrTr) that shares 50% amino acid sequence identity with GABA/choline/betaine transporters whose functions are modulated by phosphorylation. Gastrocnemius muscle was collected from adult male Sprague-Dawley (225-250 g) rats that were randomized to receive normal rat chow and distilled water ad libitum (CTL) or distilled water alone for 4 days (STV). Total Cr, phosphocreatine (PCr), free Cr, and ATP were measured luminometrically. CrTr protein expression and protein serine and tyrosine phosphorylation and mRNA expression were determined using immunoprecipitation and quantitative Western blotting and reverse transcription polymerase chain reaction (RT-PCR) analyses, respectively. Guanidinoacetate methyltransferase (GAMT) activity, guanidinoacetic acid (GAA) content, creatine kinase (CK) activity, and creatinine (Crn) content were assayed luminometrically or spectrophotometrically. Creatine transporter uptake activity was also measured in skeletal muscle membrane vesicles. Data were analyzed by t test. Total Cr and free Cr increased 26 and 280% in STV (32.3 +/- 1.0 and 12.9 +/- 1.4 vs 25.7 +/- 1.1 and 3.4 +/- 0.9 micromol/g wet wt, mean +/- SEM, respectively, P < 0.01) whereas PCr content decreased 18% (18.6 +/- 0.8 vs 22.8 +/- 0.9 micromol/g wet wt, STV vs CTL P < 0.05). CrTr protein and mRNA expression, ATP, GAA, CK, GAMT, and protein tyrosine phosphorylation of CrTr were not significantly different between the two groups. However, protein serine phosphorylation of CrTr was significantly reduced by 30% (P < 0.05) and creatine uptake activity was significantly increased (P < 0.05) in starved animals. Increases in myocellular creatine content after starvation are associated with reduced serine phosphorylation of the creatine transporter. (c) 2002 Elsevier Science (USA).

Studies on seasonal pollution of heavy metals in water, sediment, fish and oyster from the Meiliang Bay of Taihu Lake in China.

PubMed

Rajeshkumar, Sivakumar; Liu, Yang; Zhang, Xiangyang; Ravikumar, Boopalan; Bai, Ge; Li, Xiaoyu

2018-01-01

The present study, seasonal pollution of heavy metals (Pb, Cd, Cr and Cu) in water, sediment, tissues of fish Carassius carassius and oyster Crassostrea gigas were determined at seven sampling sites from Meiliang Bay, Taihu Lake during one year calendar, 2016. The total heavy metal concentrations in water samples were higher in winter and summer than in spring and autumn season, whereas in sediment they were higher in winter and summer seasons, respectively. The trend of metal mean contents found in the fish and oyster were in decreasing order of Pb > Cu > Cr > Cd and Pb > Cu > Cr > Cd, respectively. The tissues of fish and oyster captured during winter and summer accumulated a higher significant different amount of metals relative to other season, which was attributed to a higher influx of agricultural waste, sewage and sludge by heavy rainfall and floods. In addition, the pollution load index (PLI) values were above one (>1), indicating an advanced decline of the sediment quality, and contamination factor (CF) confirmed that the sediment samples were moderate to high contamination by Pb and Cr. Thus, comparative studies with seasonal pollution of heavy metals in Meiliang Bay of Lake Taihu regions indicate considerable heavy metal enrichment in water, sediments as well as in various organs of fish and oyster. Finally, our results indicated that the metal concentration values increased statistically significant different related to season (p < 0.001). The determination of heavy metal stress biomarkers in fish along with seasonal variations may serve as a convenient approach during pollution bio-monitoring programme. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of 6-month calorie restriction and exercise on serum and liver lipids and markers of liver function.

PubMed

Larson-Meyer, D Enette; Newcomer, Bradley R; Heilbronn, Leonie K; Volaufova, Julia; Smith, Steven R; Alfonso, Anthony J; Lefevre, Michael; Rood, Jennifer C; Williamson, Donald A; Ravussin, Eric

2008-06-01

Nonalcoholic fatty liver disease (NAFLD) and its association with insulin resistance are increasingly recognized as major health burdens. The main objectives of this study were to assess the relation between liver lipid content and serum lipids, markers of liver function and inflammation in healthy overweight subjects, and to determine whether caloric restriction (CR) (which improves insulin resistance) reduces liver lipids in association with these same measures. Forty-six white and black overweight men and women (BMI = 24.7-31.3 kg/m(2)) were randomized to "control (CO)" = 100% energy requirements; "CR" = 25%; "caloric restriction and increased structured exercise (CR+EX)"= 12.5% CR + 12.5% increase in energy expenditure through exercise; or "low-calorie diet (LCD)" = 15% weight loss by liquid diet followed by weight-maintenance, for 6 months. Liver lipid content was assessed by magnetic resonance spectroscopy (MRS) and computed tomography (CT). Lipid concentrations, markers of liver function (alanine aminotransferase (ALT), alkaline phosphatase (ALK)), and whole-body inflammation (tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP)) were measured in fasting blood. At baseline, increased liver lipid content (by MRS) correlated (P < 0.05) with elevated fasting triglyceride (r = 0.52), ALT (r = 0.42), and hsCRP (r = 0.33) concentrations after adjusting for sex, race, and alcohol consumption. With CR, liver lipid content was significantly lowered by CR, CR+EX, and LCD (detected by MRS only). The reduction in liver lipid content, however, was not significantly correlated with the reduction in triglycerides (r = 0.26; P = 0.11) or with the changes in ALT, high-density lipoprotein (HDL)-cholesterol, or markers of whole-body inflammation. CR may be beneficial for reducing liver lipid and lowering triglycerides in overweight subjects without known NAFLD.

[Heavy metal concentration in Nanjing urban soils and their affecting factors].

PubMed

Lu, Ying; Gong, Zitong; Zhang, Ganlin; Zhang, Bo

2004-01-01

The concentration and source of heavy metals in Nanjing urban soils and their relationships with soil properties were studied. The results indicated that the soils in Nanjing urban were not obviously polluted by Fe, Ni, Co and V, but polluted by Mn, Cr, Cu, Zn, and Pb to a certain extent. The heavy metals were irregularly distributed in soil profiles. Fe, Ni, Co, and V were originated from soil materials, but Cu, Zn, Pb, and Cr were anthropogenic input. Probably, Mn had different origins in different soils. There were positive correlations among Fe, Cr, Ni, Co, and V concentration, and among Cu, Zn, Pb, and Cr concentration. The Fe, Co, V, and Ni concentration were positively correlated with soil clay content and CEC, and the Cu, Zn and Pb concentration were negatively correlated with clay content. There were positive correlations between Cu, Zn, Pb and Cr concentration and organic C content, and between Pb concentration and soil pH.

The biological responses and metal phytoaccumulation of duckweed Spirodela polyrhiza to manganese and chromium.

PubMed

Liu, Ying; Sanguanphun, Tanatcha; Yuan, Wenqiao; Cheng, Jay J; Meetam, Metha

2017-08-01

The phytoaccumulation ability of duckweed Spirodela polyrhiza on manganese (Mn) and chromium (Cr) was assessed by exposing the plant to various concentrations of single or dual metals (5-70 mg L -1 Mn, 2-12 mg L -1 Cr(VI)) under laboratory conditions. The results showed that S. polyrhiza can tolerate Mn at high concentrations of up to 70 mg L -1 , and its growth rate was barely affected by Mn. The effects of Cr on S. polyrhiza growth were dose-dependent, and the growth was completely inhibited in the presence of 12 mg L -1 Cr. Analysis of metal content in the plant biomass revealed a high accumulation of Mn (up to 15.75 mg per g of duckweed dry weight). The Cr bioaccumulation (from below detection limit to 2.85 mg Cr (11.84 mg Cr 2 O 7 2- ) per g of duckweed dry weight) increased with cultivation time and metal concentration in the medium. Further study with the concurrence of Mn and Cr showed increased toxicity to plant growth and photosynthesis. The metal accumulations in the dual metal treatments were also significantly decreased as compared to the single metal treatments. Nevertheless, the phytoaccumulation of these two metals in S. polyrhiza in the dual metal treatments were still comparable to or higher than in previous reports. Thus, it was concluded that duckweed S. polyrhiza has the potential to be used as a phytoremediator in aquatic environments for Mn and Cr removal.

[Application of local Moran's I and GIS to identify hotspots of Ni, Cr of vegetable soils in high-incidence area of liver cancer from the Pearl River Delta, South China].

PubMed

Li, Yong; Zhou, Yong-Zhang; Zhang, Cheng-Bo; Dou, Lei; Du, Hai-Yan; Lin, Xiao-Ming; Fan, Rui; Du, Min; He, Xiang

2010-06-01

The index of local Moran's I is a useful tool for identifying hotspots of soil Ni and Cr, and for classifying them into spatial clusters and spatial outliers. To identify hotspots of vegetable soils Ni and Cr in high-incidence area of liver cancer, Shunde area of Foshan City, Pearl River Delta Economic Zone, 208 topsoil samples were collected from vegetable fields to measure the contents of nickel (Ni) and chromium (Cr). The results showed that the mean concentrations of two heavy metals Ni, Cr were 33.21 mg/kg, 80.84 mg/kg, respectively, Which were 130%, 60% higher than their soil background values of Guangdong Province, respectively. Generally, Ni is partly accumulated in soil but the accumulation of Cr is not obvious at all. The local Moran's I of Ni and Cr was calculated using 3 000, 6 000, 9 000 m as distance bands, respectively. The hotspots of Ni and Cr elements in soils were identified by local Moran's I which computed based on 6 000 m; "individual hotspots" are in the north which were affected by anthropogenic factors; "regional hotspots" are in the south which were controlled by parent materials. Moreover, the distributions of "regional hotspots" of Ni, Cr are the same as that of the highest mortality rate of liver cancer, this consistence could come up with a research direction that could reveal environmental etiologic factors of liver cancer.

Assessment of heavy metal pollution in vegetables and relationships with soil heavy metal distribution in Zhejiang province, China.

PubMed

Ye, Xuezhu; Xiao, Wendan; Zhang, Yongzhi; Zhao, Shouping; Wang, Gangjun; Zhang, Qi; Wang, Qiang

2015-06-01

There are increasing concerns on heavy metal contaminant in soils and vegetables. In this study, we investigated heavy metal pollution in vegetables and the corresponding soils in the main vegetable production regions of Zhejiang province, China. A total of 97 vegetable samples and 202 agricultural soil samples were analyzed for the concentrations of Cd, Pb, As, Hg, and Cr. The average levels of Cd, Pb, and Cr in vegetable samples [Chinese cabbage (Brassica campestris spp. Pekinensis), pakchoi (Brassica chinensis L.), celery (Apium graveolens), tomato (Lycopersicon esculentum), cucumber (Colletotrichum lagenarium), cowpea (Vigna unguiculata), pumpkin (Cucurbita pepo L.), and eggplant (Solanum melongena)] were 0.020, 0.048, and 0.043 mg kg(-1), respectively. The Pb and Cr concentrations in all vegetable samples were below the threshold levels of the Food Quality Standard (0.3 and 0.5 mg kg(-1), respectively), except that two eggplant samples exceeded the threshold levels for Cd concentrations (0.05 mg kg(-1)). As and Hg contents in vegetables were below the detection level (0.005 and 0.002 mg kg(-1), respectively). Soil pollution conditions were assessed in accordance with the Chinese Soil Quality Criterion (GB15618-1995, Grade II); 50 and 68 soil samples from the investigated area exceeded the maximum allowable contents for Cd and Hg, respectively. Simple correlation analysis revealed that there were significantly positive correlations between the metal concentrations in vegetables and the corresponding soils, especially for the leafy and stem vegetables such as pakchoi, cabbage, and celery. Bio-concentration factor values for Cd are higher than those for Pb and Cr, which indicates that Cd is more readily absorbed by vegetables than Pb and Cr. Therefore, more attention should be paid to the possible pollution of heavy metals in vegetables, especially Cd.

Long-Term Supplementation with Chromium Malate Improves Short Chain Fatty Acid Content in Sprague-Dawley Rats.

PubMed

Wu, Huiyu; Feng, Weiwei; Mao, Guanghua; Zhao, Ting; Wu, Xiangyang; Wang, Songmei; Zou, Yanmin; Yang, Liuqing; Wang, Liang

2016-11-01

Our previous study showed that chromium malate improved the composition of intestinal flora, glycometabolism, glycometabolism-related enzymes, and lipid metabolism in type 2 diabetes mellitus (T2DM) rats. The present study was designed to evaluate the effect of chromium malate with long-term supplementation on short chain fatty acid (SCFA) content in Sprague-Dawley rats. The samples were analyzed by gas chromatography with high linearity (R 2  ≥ 0.9995), low quantification limit (0.011-0.070 mM), and satisfactory recoveries. The method was simple and environmentally friendly. The acetic content in cecum of 3-month control group was significantly higher than that of 1-year control group. When compared with 1-year control group, chromium malate (at a dose of 20.0 μg Cr/kg bw) could significantly increase acetic, propionic, i-butyric butyric, butyric, i-valeric, valeric, and n-caproic levels. The acetic, propionic, i-butyric, valeric, and n-caproic contents of 1-year chromium malate group (at a dose of 20.0 μg Cr/kg bw) had a significant improvement when compared with 1-year chromium picolinate group. Acetic, propionic, and butyric contained approximately 91.65 % of the total SCFAs in 1-year group. The results indicated that the improvement of chromium malate on short chain fatty acid content change was better than that of chromium picolinate.

Experimental Constraints on the Cr Content, Oxygen Fugacity, and Petrogenesis of EETA79001 Lithology A

NASA Technical Reports Server (NTRS)

Herd, C. D. K.; Jones, J. H.; Papike, J. J.

2000-01-01

Experiments involving the composition of the groundmass of EETA79001 Lithology A constrain the Cr content of the melt and the oxygen fugacity, and suggest that overgrowth of olivine and pyroxene from the groundmass onto xenocrysts has occurred.

Synchrotron-based imaging of chromium and γ-H2AX immunostaining in the duodenum following repeated exposure to Cr(VI) in drinking water.

PubMed

Thompson, Chad M; Seiter, Jennifer; Chappell, Mark A; Tappero, Ryan V; Proctor, Deborah M; Suh, Mina; Wolf, Jeffrey C; Haws, Laurie C; Vitale, Rock; Mittal, Liz; Kirman, Christopher R; Hays, Sean M; Harris, Mark A

2015-01-01

Current drinking water standards for chromium are for the combined total of both hexavalent and trivalent chromium (Cr(VI) and Cr(III)). However, recent studies have shown that Cr(III) is not carcinogenic to rodents, whereas mice chronically exposed to high levels of Cr(VI) developed duodenal tumors. These findings may suggest the need for environmental standards specific for Cr(VI). Whether the intestinal tumors arose through a mutagenic or non-mutagenic mode of action (MOA) greatly impacts how drinking water standards for Cr(VI) are derived. Herein, X-ray fluorescence (spectro)microscopy (µ-XRF) was used to image the Cr content in the villus and crypt regions of duodena from B6C3F1 mice exposed to 180 mg/l Cr(VI) in drinking water for 13 weeks. DNA damage was also assessed by γ-H2AX immunostaining. Exposure to Cr(VI) induced villus blunting and crypt hyperplasia in the duodenum--the latter evidenced by lengthening of the crypt compartment by ∼2-fold with a concomitant 1.5-fold increase in the number of crypt enterocytes. γ-H2AX immunostaining was elevated in villi, but not in the crypt compartment. µ-XRF maps revealed mean Cr levels >30 times higher in duodenal villi than crypt regions; mean Cr levels in crypt regions were only slightly above background signal. Despite the presence of Cr and elevated γ-H2AX immunoreactivity in villi, no aberrant foci indicative of transformation were evident. These findings do not support a MOA for intestinal carcinogenesis involving direct Cr-DNA interaction in intestinal stem cells, but rather support a non-mutagenic MOA involving chronic wounding of intestinal villi and crypt cell hyperplasia. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology.

Characterization of type 2 diacylglycerol acyltransferases in Chlamydomonas reinhardtii reveals their distinct substrate specificities and functions in triacylglycerol biosynthesis.

PubMed

Liu, Jin; Han, Danxiang; Yoon, Kangsup; Hu, Qiang; Li, Yantao

2016-04-01

Diacylglycerol acyltransferases (DGATs) catalyze a rate-limiting step of triacylglycerol (TAG) biosynthesis in higher plants and yeast. The genome of the green alga Chlamydomonas reinhardtii has multiple genes encoding type 2 DGATs (DGTTs). Here we present detailed functional and biochemical analyses of Chlamydomonas DGTTs. In vitro enzyme analysis using a radiolabel-free assay revealed distinct substrate specificities of three DGTTs: CrDGTT1 preferred polyunsaturated acyl CoAs, CrDGTT2 preferred monounsaturated acyl CoAs, and CrDGTT3 preferred C16 CoAs. When diacylglycerol was used as the substrate, CrDGTT1 preferred C16 over C18 in the sn-2 position of the glycerol backbone, but CrDGTT2 and CrDGTT3 preferred C18 over C16. In vivo knockdown of CrDGTT1, CrDGTT2 or CrDGTT3 resulted in 20-35% decreases in TAG content and a reduction of specific TAG fatty acids, in agreement with the findings of the in vitro assay and fatty acid feeding test. These results demonstrate that CrDGTT1, CrDGTT2 and CrDGTT3 possess distinct specificities toward acyl CoAs and diacylglycerols, and may work in concert spatially and temporally to synthesize diverse TAG species in C. reinhardtii. CrDGTT1 was shown to prefer prokaryotic lipid substrates and probably resides in both the endoplasmic reticulum and chloroplast envelope, indicating its role in prokaryotic and eukaryotic TAG biosynthesis. Based on these findings, we propose a working model for the role of CrDGTT1 in TAG biosynthesis. This work provides insight into TAG biosynthesis in C. reinhardtii, and paves the way for engineering microalgae for production of biofuels and high-value bioproducts. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

The effect of copper, chromium, and zirconium on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloys

NASA Technical Reports Server (NTRS)

Wagner, John A.; Shenoy, R. N.

1991-01-01

The present study evaluates the effect of the systematic variation of copper, chromium, and zirconium contents on the microstructure and mechanical properties of a 7000-type aluminum alloy. Fracture toughness and tensile properties are evaluated for each alloy in both the peak aging, T8, and the overaging, T73, conditions. Results show that dimpled rupture essentially characterize the fracture process in these alloys. In the T8 condition, a significant loss of toughness is observed for alloys containing 2.5 pct Cu due to the increase in the quantity of Al-Cu-Mg-rich S-phase particles. An examination of T8 alloys at constant Cu levels shows that Zr-bearing alloys exhibit higher strength and toughness than the Cr-bearing alloys. In the T73 condition, Cr-bearing alloys are inherently tougher than Zr-bearing alloys. A void nucleation and growth mechanism accounts for the loss of toughness in these alloys with increasing copper content.

Source identification of eight hazardous heavy metals in agricultural soils of Huizhou, Guangdong Province, China.

PubMed

Cai, Limei; Xu, Zhencheng; Ren, Mingzhong; Guo, Qingwei; Hu, Xibang; Hu, Guocheng; Wan, Hongfu; Peng, Pingan

2012-04-01

One hundred and four surface samples and 40 profiles samples in agricultural soils collected from Huizhou in south-east China were monitored for total contents of 8 heavy metals, and analyzed by multivariate statistical techniques and enrichment factor (EF), in order to investigate their origins. The results indicate that the concentrations of Cu, Zn, Ni, Cr, Pb, Cd, As and Hg in soils are 16.74, 57.21, 14.89, 27.61, 44.66, 0.10, 10.19 and 0.22 mg/kg, respectively. Compared to the soil background contents in Guangdong Province, the mean concentrations of Hg, Cd, Zn, Pb and As in soil of Huizhou are higher, especially Hg and Cd, which are 2.82 and 1.79 times the background values, respectively. Cr, Ni, Cu, partially, Zn and Pb mainly originate from a natural source. Cd, As, partially, Zn mainly come from agricultural practices. However, Hg, partially, Pb originate mainly from industry and traffic sources. Copyright © 2011 Elsevier Inc. All rights reserved.

Microalgae cultivation for bioenergy production using wastewaters from a municipal WWTP as nutritional sources.

PubMed

Cho, Sunja; Lee, Nakyeong; Park, Seonghwan; Yu, Jaecheul; Luong, Thanh Thao; Oh, You-Kwan; Lee, Taeho

2013-03-01

In order to reduce input cost for microalgal cultivation, we investigated the feasibility of wastewater taken from a municipal WWTP in Busan, Korea as wastewater nutrients. The wastewaters used in this study were the effluent from a primary settling tank (PS), the effluent from an anaerobic digestion tank (AD), the conflux of wastewaters rejected from sludge-concentrate tanks and dewatering facilities (CR), and two combined wastewaters of AD:PS (10:90, v/v) and AD:CR (10:90, v/v). Chlorella sp. ADE5, which was isolated from the AD, was selected for the feasibility test. The highest biomass production (3.01 g-dry cell weight per liter) of the isolate was obtained with the combined wastewater ADCR, and it was 1.72 times higher than that with BG 11 medium. Interestingly, the cells cultivated with wastewater containing PS wastewater were easily separated from the culture and improved lipid content, especially oleic acid content, in their cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microstructure of rapidly solidified Nb-based pre-alloyed powders for additive manufacturing

NASA Astrophysics Data System (ADS)

Guo, Yueling; Jia, Lina; Kong, Bin; Zhang, Shengnan; Zhang, Fengxiang; Zhang, Hu

2017-07-01

For powder-based additive manufacturing, sphere-shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by plasma rotating electrode processing (PREP). The microstructure, surface oxidation and microhardness of the pre-alloyed powders were systematically investigated. Results showed that the main phases were Nb solid solution (Nbss) and Cr2Nb. The Cr2Nb phases were further determined using transmission electron microscopy (TEM). Fine dendrite structures were observed in the as-fabricated pre-alloyed powders, which transformed to large grains after heat treatment (HT) at 1450 °C for 3 h. With the increase of powder size, the secondary dendrite arm spacing (SDAS) increased and the microhardness (HV) decreased. A clean powder surface free of oxide particles was obtained by PREP and an oxide layer with 9.39 nm in thickness was generated on the powder surface. Compared with Cr- and Nb-oxides, more Ti-oxides were formed on outmost powder surface with a higher content of Ti (up to 47.86 at.%). The differences upon the microstructure and microhardness of the pre-alloyed powders with different sizes were discussed.

Effect of Cr Contents and Heat Treating on Reverted Austenite in Maraging Steel Weldments

NASA Astrophysics Data System (ADS)

Kim, S. W.; Lee, H. W.

2018-05-01

By conducting flux cored arc welding (FCAW) on maraging steels with Cr contents of 1.4 and 5.2 wt%, this study observed the effects of Cr content and heat treating on reverted austenite formation in welded maraging steel. Aging treatment was carried out at the temperatures of 450, 480 and 530 °C for 3 h in each condition. As the aging temperature increased, reverted austenite was formed along the interdendritic and intercellular grain boundaries, and the proportion of reverted austenite increased with increasing Cr addition. The aging process led to the segregation of Ti and Mo along the interdendritic and intercellular grain boundaries. Some of the welded specimens were subjected to solution heat treatment at 820 and 1250 °C for 1 h after welding, resulting in a decrease in reverted austenite fraction.

Effect of Cr Contents and Heat Treating on Reverted Austenite in Maraging Steel Weldments

NASA Astrophysics Data System (ADS)

Kim, S. W.; Lee, H. W.

2018-03-01

By conducting flux cored arc welding (FCAW) on maraging steels with Cr contents of 1.4 and 5.2 wt%, this study observed the effects of Cr content and heat treating on reverted austenite formation in welded maraging steel. Aging treatment was carried out at the temperatures of 450, 480 and 530 °C for 3 h in each condition. As the aging temperature increased, reverted austenite was formed along the interdendritic and intercellular grain boundaries, and the proportion of reverted austenite increased with increasing Cr addition. The aging process led to the segregation of Ti and Mo along the interdendritic and intercellular grain boundaries. Some of the welded specimens were subjected to solution heat treatment at 820 and 1250 °C for 1 h after welding, resulting in a decrease in reverted austenite fraction.

Minor elements in lunar olivine as a petrologic indicator

NASA Technical Reports Server (NTRS)

Steele, I. M.; Smith, J. V.

1975-01-01

Accurate electron microprobe analyses (approximately 50 ppm) were made for Al, Ca, Ti, Cr, Mn, and Ni in Mg-rich olivines which may derive from early lunar crust or deeper environments. Low-Ca contents consistently occur only in olivines from dunitic and troctolitic breccia: spinel troctolite and other rock types have high-Ca olivines suggesting derivation by near-surface processes. Rock 15445 has olivine with distinctly low CaO (approximately 0.01 wt.%). Chromium ranges to higher values (max.0.2 oxide wt.%) than for terrestrial harzburgites and lherzolites but is similar to the range in terrestrial komatiites. Divalent chromium may be indicated over trivalent Cr because olivines lack sufficient other elements for charge balance of the latter. NiO values in lunar specimens range from 0.00 to 0.07 wt.% and a weak anticorrelation with Cr2O3 suggests an oxidation state effect. Al2O3 values are mostly below 0.04-wt.% and show no obvious correlation with fragment type. TiO2 values lie below 0.13-wt.% and seem to correlate best with crystallization rate and plagioclase content of the host rock. High values of Al2O3 and TiO2 reported by other workers have not been confirmed, and are probably wrong.

Terrestrial and marine biomarker estimates of organic matter sources and distributions in surface sediments from the East China Sea shelf

NASA Astrophysics Data System (ADS)

Xing, Lei; Zhang, Hailong; Yuan, Zineng; Sun, Yao; Zhao, Meixun

2011-07-01

Revealing of the sources and distributions of sedimentary organic matter in the East China Sea (ECS) is important for understanding its carbon cycle, which has significant temporal and spatial variability due to the influences of recent climate changes and anthropogenic activities. In this study, we report the contents of both terrestrial and marine biomarkers including ∑C 27+C 29+C 31n-alkanes (38.6-580 ng/g), C 37 alkenones (5.6-124.6 ng/g), brassicasterol (98-913 ng/g) and dinosterol (125-1521 ng/g) from the surface sediments in the Changjiang River Estuary (CRE) and shelf areas of the ECS. Several indices based on biomarker contents and ratios are calculated to assess the spatial distributions of both terrestrial and marine organic matter in the ECS surface sediments, and these results are compared with organic matter distribution patterns revealed by the δ13C (-20.1‰ to -22.7‰) and C/N ratio (5-7.5) of total organic matter. The contents of terrestrial biomarkers in the ECS surface sediments decrease seaward, controlled mostly by Changjiang River (CR) inputs and surface currents; while higher contents of the two marine biomarkers (brassicasterol and dinosterol) occur in upwelling areas outside the CRE and in the Zhejiang-Fujian coastal zone, controlled mostly by marine productivity. Four proxies, fTerr( δ13C) (the fraction of terrestrial organic matter in TOC estimated by TOC δ13C), odd-alkanes (∑C 27+C 29+C 31n-alkanes), 1/ Pmar-aq ((C 23+C 25+C 29+C 31)/(C 23+C 25) n-alkanes) and TMBR (terrestrial and marine biomarker ratio) (C 27+C 29+C 31n-alkanes)/((C 27+C 29+C 31) n-alkanes+(brassicasterol+dinosterol+alkenones)), reveal a consistent pattern showing the relative contribution of terrestrial organic matter (TOM) is higher in the CRE and along the Zhejiang-Fujian coastline, controlled mostly by CR inputs and currents, but the TOM contribution decreases seaward, as the influences of the CR discharge decrease.

Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI).

PubMed

Hedberg, Yolanda S; Lidén, Carola; Odnevall Wallinder, Inger

2014-09-15

About 1-3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pH<6.5) and phosphate buffer (PB, pH 7.5-8.0), measured by means of spectrophotometry and atomic absorption spectroscopy. Co-released leather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB). Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Hypoxia decreases creatine uptake in cardiomyocytes, while creatine supplementation enhances HIF activation.

PubMed

Santacruz, Lucia; Arciniegas, Antonio Jose Luis; Darrabie, Marcus; Mantilla, Jose G; Baron, Rebecca M; Bowles, Dawn E; Mishra, Rajashree; Jacobs, Danny O

2017-08-01

Creatine (Cr), phosphocreatine (PCr), and creatine kinases (CK) comprise an energy shuttle linking ATP production in mitochondria with cellular consumption sites. Myocytes cannot synthesize Cr: these cells depend on uptake across the cell membrane by a specialized creatine transporter (CrT) to maintain intracellular Cr levels. Hypoxia interferes with energy metabolism, including the activity of the creatine energy shuttle, and therefore affects intracellular ATP and PCr levels. Here, we report that exposing cultured cardiomyocytes to low oxygen levels rapidly diminishes Cr transport by decreasing V max and K m Pharmacological activation of AMP-activated kinase (AMPK) abrogated the reduction in Cr transport caused by hypoxia. Cr supplementation increases ATP and PCr content in cardiomyocytes subjected to hypoxia, while also significantly augmenting the cellular adaptive response to hypoxia mediated by HIF-1 activation. Our results indicate that: (1) hypoxia reduces Cr transport in cardiomyocytes in culture, (2) the cytoprotective effects of Cr supplementation are related to enhanced adaptive physiological responses to hypoxia mediated by HIF-1, and (3) Cr supplementation increases the cellular ATP and PCr content in RNCMs exposed to hypoxia. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Effect and removal mechanisms of 6 different washing agents for building wastes containing chromium.

PubMed

Xing-run, Wang; Yan-xia, Zhang; Qi, Wang; Jian-min, Shu

2012-01-01

With the building wastes contaminated by chromium in Haibei Chemical Plan in China as objects, we studied the contents of total Cr and Cr (VI) of different sizes, analyzed the effect of 6 different washing agents, discussed the removal mechanisms of 6 different washing agents for Cr in various forms, and finally selected applicable washing agent. As per the results, particle size had little impact on the contents of total Cr and Cr (VI); after one washing with water, the removal rate of total Cr and Cr (VI) was 75% and 78%, respectively, and after the second washing with 6 agents, the removal rate of citric acid was the highest, above 90% for total Cr and above 99% for hexavalent chromium; the pH of building wastes were reduced by citric acid, and under acid condition, hexavalent chromium was reduced to trivalent chromium spontaneously by organic acid, which led to better removal rate of acid soluble Cr and reducible Cr; due to the complexing action, citric acid had best removal rate for oxidizable trivalent chromium. In conclusion, citric acid is the most applicable second washing agent for building wastes.

Microstructural characteristics of σ phase and P phase in Ru-containing single crystal superalloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huo, Jiajie, E-mail: jiajiehuo0618@163.com

Microstructural instability caused by topologically close-packed (TCP) phase precipitation restricts the useful compositional range of advanced Ni-base single crystal superalloys in industrial applications. Limited systematic investigations of TCP formers (Cr and Mo) additions on microstructural evolution of both the σ phase and the P phase in Ru-containing single crystal superalloys have been reported. In this study, the microstructural characteristics of σ phase and P phase were investigated in three Ru-containing superalloys with different levels of Cr and Mo additions at 950 °C and 1100 °C by using phase extraction, X-ray diffraction, scanning electron microscope and high resolution transmission electron microscopy.more » The experimental results indicated that the high level additions of Cr and Mo promoted the formation of σ phase and P phase, respectively. The amount of σ phase was much higher than that of P phase after long term exposure at 950 °C and 1100 °C. The sheet-like σ phase existed in the alloy with higher Cr addition after thermal exposure at 950 °C and 1100 °C for 1000 h, while the needle-like P phase precipitated in high Mo content alloy after thermal exposure at 1100 °C for 1000 h and the intergrowth of σ phase and P phase was observed after thermal exposure at 950 °C for 500 h. Both the σ phase and P phase were enriched in Re, W, Cr and Mo, but the σ phase contained more Re and Cr while the P phase contained more Mo and Ni, and Ru was found in both phases. The nucleation of σ phase was much easier than P phase due to the more ledge steps in the interfacial structure between σ phase and matrix, as well as the higher partitioning ratios of Re, Cr and Mo. This study is helpful to understand the microstructural evolution of σ phase and P phase, and to optimize the alloy design in Ru-containing superalloys. - Highlights: •Microstructures of σ phase and P phase were characterized in detail. •Cr and Mo influenced the precipitation of σ phase and P phase, respectively. •Partitioning ratios and interfacial relationship decided precipitation behaviors.« less

Design of Novel Precipitate-Strengthened Al-Co-Cr-Fe-Nb-Ni High-Entropy Superalloys

NASA Astrophysics Data System (ADS)

Antonov, Stoichko; Detrois, Martin; Tin, Sammy

2018-01-01

A series of non-equiatomic Al-Co-Cr-Fe-Nb-Ni high-entropy alloys, with varying levels of Co, Nb and Fe, were investigated in an effort to obtain microstructures similar to conventional Ni-based superalloys. Elevated levels of Co were observed to significantly decrease the solvus temperature of the γ' precipitates. Both Nb and Co in excessive concentrations promoted the formation of Laves and NiAl phases that formed either during solidification and remained undissolved during homogenization or upon high-temperature aging. Lowering the content of Nb, Co, or Fe prevented the formation of the eutectic type Laves. In addition, lowering the Co content resulted in a higher number density and volume fraction of the γ' precipitates, while increasing the Fe content led to the destabilization of the γ' precipitates. Various aging treatments were performed which led to different size distributions of the strengthening phase. Results from the microstructural characterization and hardness property assessments of these high-entropy alloys were compared to a commercial, high-strength Ni-based superalloy RR1000. Potentially, precipitation-strengthened high-entropy alloys could find applications replacing Ni-based superalloys as structural materials in power generation applications.

GABA content within the ventromedial prefrontal cortex is related to trait anxiety.

PubMed

Delli Pizzi, Stefano; Padulo, Caterina; Brancucci, Alfredo; Bubbico, Giovanna; Edden, Richard A; Ferretti, Antonio; Franciotti, Raffaella; Manippa, Valerio; Marzoli, Daniele; Onofrj, Marco; Sepede, Gianna; Tartaro, Armando; Tommasi, Luca; Puglisi-Allegra, Stefano; Bonanni, Laura

2016-05-01

The ventromedial prefrontal cortex (vmPFC) plays a key role in emotion processing and regulation. vmPFC dysfunction may lead to disinhibition of amygdala causing high anxiety levels. γ-Aminobutyric acid (GABA) inter-neurons within vmPFC shape the information flow to amygdala. Thus, we hypothesize that GABA content within vmPFC could be relevant to trait anxiety. Forty-three healthy volunteers aged between 20 and 88 years were assessed for trait anxiety with the Subscale-2 of the State-Trait-Anxiety Inventory (STAI-Y2) and were studied with proton magnetic resonance spectroscopy to investigate GABA and Glx (glutamate+glutamine) contents within vmPFC. Total creatine (tCr) was used as internal reference. Partial correlations assessed the association between metabolite levels and STAI-Y2 scores, removing the effect of possible nuisance factors including age, educational level, volumes of gray matter and white matter within magnetic resonance spectroscopy voxel. We observed a positive relationship between GABA/tCr and STAI-Y2 scores. No significant relationships were found between Glx/tCr and STAI-Y2 and between tCr/water and STAI-Y2. No differences were found between males and females as regards to age, STAI-Y2, GABA/tCr, Glx/tCr, tCr/water, gray matter and white matter volumes. We suggest a close relationship between GABA content within vmPFC and trait anxiety providing new insights in the physiology of emotional brain. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Effect of Cr2O3 Pickup on Dissolution of Lime in Converter Slag

NASA Astrophysics Data System (ADS)

Yan, Wei; Chen, Weiqing; Zhao, Xiaobo; Yang, Yindong; McLean, Alex

2017-09-01

Application of low-nickel laterite ore containing chromium as charging material for ironmaking can reduce raw material costs, but result in an increase of chromium content in the hot metal and hence, Cr2O3 content in the steelmaking slag, which subsequently causes many problems related to lime dissolution for the steelmaking operation. In this work, a rotating cylinder method was employed to study the effect of Cr2O3 on lime dissolution in steelmaking slag. The lime dissolution mechanism, rate control step and affecting factors, including slag basicity, FeOx and B2O3 content, and the formation of phases at reacted layer, were discussed. It was found that mass transfer was the rate control step in slag phase, increase of Cr2O3 and slag basicity delayed lime dissolution due to the formation of high-melting temperature phases of FeO · Cr2O3 spinel and 2CaO · SiO2 at the slag/lime reacted interface. Addition of B2O3 promoted lime dissolution and suppressed formation of FeO · Cr2O3 spinel.

Selenium-methionine and chromium-methionine supplementation of sheep around parturition: impacts on dam and offspring performance.

PubMed

Mousaie, Amir; Valizadeh, Reza; Chamsaz, Mahmoud

2017-04-01

To examine the effects of maternal energy restriction along with selenium-methionine (Se-Met) and chromium-methionine (Cr-Met) supplementation on performance of pregnant sheep and their offspring, the following treatments were allotted randomly to 40 multiparous Baluchi ewes (53.9 ± 1.15 kg of body weight [BW]) from 5 weeks prior to 5 weeks after parturition: (1) Control diet (60% and 100% of NRC energy requirements in pre- and post-partum, respectively); (2) Control diet plus 5 mg Se-Met/kg dry matter (DM); (3) Control diet plus 3 mg Cr-Met/kg DM and (4) Control diet plus 5 mg Se-Met and 3 mg Cr-Met/kg DM (Se-Cr-Met) of concentrate diet. The results indicated that Cr-Met alone or in combination with Se-Met increased average DM intake of ewes. In addition, Group Cr-Met had higher average BW than the Control (p < 0.05). Se-Met and/or Cr-Met supplementation led to decreased average serum cholesterol of the ewes (p < 0.05). Groups Cr-Met and Se-Cr-Met displayed decreased average serum malondialdehyde compared to the Control (p < 0.05). At 24 h post-partum, Group Se-Cr-Met had a greater serum Se content than the Control (p = 0.006). Compared with the Control, the Se concentration in milk was significantly increased from 30 to 138 µg/l and 197 µg/l in Groups Se-Met and Se-Cr-Met, respectively (p < 0.01), which proved that Se-Met supplementation can increase the Se concentration of ewe milk. Furthermore, feeding Cr-Met may attenuate BW loss post-partum and Se-Met and/or Cr-Met supplements may ameliorate oxidative stress condition in ewes around parturition.

Fraction distribution and risk assessment of heavy metals in waste clay sediment discharged through the phosphate beneficiation process in Jordan.

PubMed

Al-Hwaiti, Mohammad Salem; Brumsack, Hans Jurgen; Schnetger, Bernhard

2015-07-01

Heavy metal contamination of clay waste through the phosphate beneficiation process is a serious problem faced by scientists and regulators worldwide. Through the beneficiation process, heavy metals naturally present in the phosphate rocks became concentrated in the clay waste. This study evaluated the concentration of heavy metals and their fractions in the clay waste in order to assess the risk of environmental contamination. A five-step sequential extraction method, the risk assessment code (RAC), effects range low (ERL), effects range medium (ERM), the lowest effect level (LEL), the severe effect level (SEL), the redistribution index (U tf), the reduced partition index (I), residual partition index (I R), and the Nemerow multi-factor index (PC) were used to assess for clay waste contamination. Heavy metals were analyzed using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Correlation analyses were carried out to better understand the relationships between the chemical characteristics and the contents of the different phase fractions. Concentrations of Cd and Cu confirmed that both were bound to the exchangeable fraction (F1) and the carbonate fraction (F2), presenting higher mobility, whereas Pb was most abundant in the Fe-Mn oxide fraction (F3) and organic matter fraction (F4). The residual fraction (F5) contained the highest concentrations (>60%) of As, Cr, Mo, V, and Zn, with lower mobility. Application of the RAC index showed that Cd and Cu should be considered a moderate risk, whereas As, Cr, Mo, Pb, and Zn presented a low risk. Cadmium and Cu contents in mobile fractions F1 and F2 were higher than ERL but lower than ERM. On the other hand, As, Pb, and Zn contents of mobile fractions F1 and F2 were lower than ERL and ERM guideline values. Moreover, total Pb concentrations in the clay waste were below the lowest effect level (LEL) threshold value period, Cr and Zn values in the clay waste were determined to have exceeded the severe effect level (SEL) limit values, whereas Cd and Cu level ranges between LEL and SEL indicate moderate contamination. I R values of heavy metals in the clay waste confirmed that Cd and Cu were bound to the exchangeable and carbonate fractions and presented higher mobility, whereas As, Cr, Mo, Pb, V, and Zn were bound to organic or residual fractions and consequently exhibit lower mobility. A Nemerow multi-factor index revealed that the mine site contains high levels of Cd, Cu, V, and Zn pollution. As and Cr were found at a moderate level of contamination, whereas Pb was present at a safe level of contamination. The order of the comprehensive contamination indices was Cd > Cu > Mo > Zn > V > Cr > As > Pb, indicating that the assessment of clay waste, especially with Cd and Cu, should be undertaken to control heavy metal contamination in adjacent urban and mine areas at the Eshidiya mines.

Determination of Heavy Metals in Almonds and Mistletoe as a Parasite Growing on the Almond Tree Using ICP-OES or ICP-MS.

PubMed

Kamar, Veysi; Dağalp, Rukiye; Taştekin, Mustafa

2017-12-28

In this study, the elements of Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, Sr, Pb, Ti, and Zn were determined in the leaves, fruits, and branches of mistletoe, (Viscum albüm L.), used as a medicinal plant, and in the leaves, branches and barks of almond tree which mistletoe grows on. The aim of the study is to investigate whether the mistletoe are more absorbent than the almond tree in terms of the heavy metal contents and the determination of the amount of the elements penetrated into the mistletoe from the almond tree. ICP-MS (inductively coupled plasma-mass spectrometry) was used for the analysis of As, Cd, Mo, and Pb, whereas ICP-OES (inductively coupled plasma optical emission spectrometry) was used for the other elements. The results obtained were statistically evaluated at 95% confidence level. Within the results obtained in this study, it was determined whether there is a significant difference between metal elements in almond tree and mistletoe, or not. As a result, it was observed that there were higher contents of B, Ba, K, Mg, and Zn in the mistletoe than in the almond tree. K was found much higher than other elements in the mistletoe. On the other hand, Al, As, Ca, Cd, Cr, Cu, Fe, Mo, Ni, Sr, Pb, and Ti contents were determined to be more in almond tree than mistletoe.

Towards a Social Networks Model for Online Learning & Performance

ERIC Educational Resources Information Center

Chung, Kon Shing Kenneth; Paredes, Walter Christian

2015-01-01

In this study, we develop a theoretical model to investigate the association between social network properties, "content richness" (CR) in academic learning discourse, and performance. CR is the extent to which one contributes content that is meaningful, insightful and constructive to aid learning and by social network properties we…

Control of the electrical resistivity of Ni-Cr wires using low pressure chemical vapor deposition of tin

NASA Astrophysics Data System (ADS)

Kim, Jun-Hyun; Bak, Jeong Geun; Lee, Kangtaek; Kim, Chang-Koo

2018-01-01

Control of the electrical resistivity of Ni-Cr wires is demonstrated using low pressure chemical vapor deposition (LPCVD) of tin on the surface of the wire, after which the effects of the deposition temperature on the structural, morphological, and compositional characteristics of the tin-deposited Ni-Cr wires are investigated. As the deposition temperature is increased, the resistivity of the Ni-Cr wires increases in the temperature range 300-400 °C; then remains nearly constant as the temperature increased to 700 °C. The increase in the resistivity of the Ni-Cr wires is attributed to formation of Ni3Sn2 particulates on the surface of the wire. Compositional analysis shows that the pattern of change in the tin content with the deposition temperature is similar to that of resistivity with temperature, implying that the atomic content of tin on Ni-Cr directly affects the electrical resistivity.

Effects of Cr 3+ impurity concentration on the crystallography of synthetic emerald crystals

NASA Astrophysics Data System (ADS)

Lee, Pei-Lun; Huang, Eugene; Lee, Jan-Shing; Yu, Shu-Cheng

2011-06-01

Flux method has been adopted for the synthesis of emerald crystals using PbO-V 2O 5 as a flux in order to study the crystallography of the synthetic crystals. In general, the hue of green color of emerald deepens with the addition of Cr 3+. The molar volume of the synthesized crystals was found to increase with the incorporation of Cr 2O 3 dopant. The substitution of Cr 3+ for Al 3+ in the octahedral sites of beryl results in the expansion of a-axis, while c-axis remains nearly unchanged. The maximum Cr 2O 3-content allowed in the crystal lattice of emerald has been found to be about 3.5 wt%. When the doping Cr 2O 3-content exceeds 3.5 wt%, a significant anomaly in lattice parameters starts to take place, accompanying the precipitation of an unknown phase in the emerald matrix.

Recent progress in the study of protective rust-layer formation on weathering steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamashita, M.; Misawa, T.

Latest understanding of protective rust layer on weathering steel and its application for structural steels is discussed. Phase transformation of the weathering steel rust layer during long-time exposure brings {alpha}-(Fe{sub 1{minus}x},Cr{sub x})OOH, Cr-substituted goethite, as the final protective rust layer. It is said that the Cr content in the Cr-substituted goethite layer increases gradiently with reaching the rust-steel interface. This increase in the Cr content gives densely packed fine crystal structure end cation selective ability, which impedes the penetration of aggressive corrosives including anions such as Cl{sup {minus}} and SO{sub 4}{sup 2{minus}}. Quite recently, new surface-treatment technique employing Cr{sub 2}(SO{submore » 4}){sub 3}, was proposed, which provides a possibility for obtaining the protective rust layer in a relatively short period even in the severe environment such as coastal region.« less

Development and High Temperature Property Evaluation of Ni-Co-Cr-Al Composite Electroforms

NASA Astrophysics Data System (ADS)

Srivastava, Meenu; Siju; Balaraju, J. N.; Ravisankar, B.

2015-05-01

Ni-Co-Cr-Al composite electroforms were developed with cobalt content of 10 and 40 wt.%. Cr and Al nano-particles were suspended in sulphamate electrolyte and co-deposited in the Ni-Co matrices. The surface morphology was investigated using field emission scanning electron microscope and the composition analyzed by energy-dispersive x-ray analysis. The oxidation resistance of the electroforms was studied from 600 to 1000 °C. The weight gain of Ni-10 wt.%Co-Cr-Al was less (better oxidation resistance) compared to Ni-Cr-Al and Ni-40 wt.%Co-Cr-Al. The x-ray diffraction studies revealed that the oxidation product formed on the surface of Ni-Cr-Al and Ni-10 wt.%Co-Cr-Al consisted of NiO and Al2O3, while Ni-40 wt.%Co-Cr-Al comprised oxides such as NiCo2O4, CrO3, CoO, NiO, and Al2O3. The hot corrosion behavior was investigated in 75%Na2SO4 + 25%NaCl environment at 800 °C. It was found that the hot corrosion resistance of the composite coating improved with increase in cobalt content. The probable composition suitable for high-temperature applications was found to be Ni-10 wt.%Co-Cr-Al.

The effect of Be and Cr electrode deposition rate on the performance of MIS solar cells

NASA Astrophysics Data System (ADS)

Moharram, A. H.; Panayotatos, P.; Yeh, J. L.; Lalevic, B.

1985-07-01

An experimental study has been performed on MIS solar cells with Be, Cr and layered Cr-Be electrodes on single crystal Si, Wacker and Monsanto poly-Si substrates. Electrical characterization in the dark and under illumination was correlated to X-ray and Auger spectroscopy results. It was found that the electrode deposition rate directly affects the oxygen content of the electrodes for all metal-substrate configurations. This oxygen is believed to originate from the deposition ambient as well as from the SiO2 layer. In the case of cells with Cr and layered Cr-Be electrodes oxygen acts to reduce the electrode work function (thus increasing the open-circuit voltage) in direct proportion to the relative content of oxygen to chromium.

Effect of chemical composition of Ni-Cr dental casting alloys on the bonding characterization between porcelain and metal.

PubMed

Huang, H-H; Lin, M-C; Lee, T-H; Yang, H-W; Chen, F-L; Wu, S-C; Hsu, C-C

2005-03-01

The purpose of this study was to investigate the influence of chemical composition of Ni-Cr dental casting alloys on the bonding behaviour between porcelain and metal. A three-point bending test was used to measure the fracture load of alloy after porcelain firing. A scanning electron microscope, accompanied by an energy dispersion spectrometer, was used to analyse the morphology and chemical composition of the fracture surface. An X-ray photoelectron spectrometer and glow discharge spectrometer were used to identify the structure and cross-sectional chemical composition, respectively, of oxide layers on Ni-Cr alloys after heat treatment at 990 degrees C for 5 min. Results showed that the oxide layers formed on all Ni-Cr alloys contained mainly Cr2O3, NiO, and trace MoO3. The Ni-Cr alloy with a higher Cr content had a thicker oxide layer, as well as a weaker bonding behaviour of porcelain/metal interface. The presence of Al (as Al2O3) and Be (as BeO) on the oxide layer suppressed the growth of the oxide layer, leading to a better porcelain/metal bonding behaviour. However, the presence of a small amount of Ti (as TiO2) on the oxide layer did not have any influence on the bonding behaviour. The fracture propagated along the interface between the opaque porcelain and metal, and exhibited an adhesive type of fracture morphology.

Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase

PubMed Central

Montori-Grau, Marta; Minor, Robin; Lerin, Carles; Allard, Joanne; Garcia-Martinez, Celia; de Cabo, Rafael; Gómez-Foix, Anna M.

2016-01-01

Calorie restriction’s (CR) effects on age-associated changes in glycogen-metabolizing enzymes were studied in rat soleus (SOL) and tibialis anterior (TA) muscles. Old (24 months) compared to young (6 months) rats maintained ad libitum on a standard diet had reduced glycogen synthase (GS) activity, lower muscle GS protein levels, increased phosphorylation of GS at site 3a with less activation in SOL. Age-associated impairments in GS protein and activation-phosphorylation were also shown in TA. There was an age-associated reduction in glycogen phosphorylase (GP) activity level in SOL, while brain/muscle isoforms (B/M) of GP protein levels were higher. GP activity and protein levels were preserved, but GP was inactivated in TA with age. Glycogen content was unchanged in both muscles. CR did not alter GS or GP activity/protein levels in young rats. CR hindered age-related decreases in GS activity/protein, unrelated to GS mRNA levels, and GS inactivation-phosphorylation; not on GP. In older rats, CR enhanced glycogen accumulation in SOL. Short-term fasting did not recapitulate CR effects in old rats. Thus, the predominant age-associated impairments on skeletal muscle GS and GP activities occur in the oxidative SOL muscle of rats, and CR can attenuate the loss of GS activity/activation and stimulate glycogen accumulation. PMID:19341787

Metal-induced oxidative stress in terrestrial macrolichens.

PubMed

Kováčik, Jozef; Dresler, Sławomir; Peterková, Viera; Babula, Petr

2018-07-01

Short-term (24 h) responses of Cladonia arbuscula subsp. mitis and Cladonia furcata to copper (CuII) or chromium (CrIII) excess (10 or 100 μM) were compared. C. arbuscula accumulated more Cu and Cr at higher metal doses but both species revealed depletion of K and/or Ca amount. Not only Cu but also Cr typically elevated reactive oxygen species (ROS) formation (fluorescence microscopy detection of total ROS and hydrogen peroxide) and depleted nitric oxide (NO) signal, with Cu showing more negative impact on lipid peroxidation (BODIPY 581/591 C11 staining reagent). Metals and staining reagents also affected anatomical responses and photobiont/mycobiont visibility. Principally different impact of Cu and Cr was observed at antioxidative metabolites level, indicating various ways of metal-induced ROS removal and/or metal chelation: Cu strongly depleted glutathione (GSH) and stimulated phytochelatin 2 (PC2) content while ascorbic acid accumulation was depleted by Cu and stimulated by Cr. Subsequent experiment with GSH biosynthetic inhibitor (buthionine sulfoximine, BSO) revealed that 48 h of exposure is needed to deplete GSH and BSO-induced depletion of GSH and PC2 amounts under Cu or Cr excess elevated ROS but depleted NO. These data suggest close relations between thiols, NO and appearance of oxidative stress (ROS generation) under metallic stress also in lichens. Copyright © 2018 Elsevier Ltd. All rights reserved.

Corrosion property of 9Cr-ODS steel in nitric acid solution for spent nuclear fuel reprocessing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeuchi, M.; Koizumi, T.; Inoue, M.

2013-07-01

Corrosion tests of oxide dispersion strengthened with 9% Cr (9Cr-ODS) steel, which is one of the desirable materials for cladding tube of sodium-cooled fast reactors, in pure nitric acid solution, spent FBR fuel solution, and its simulated solution were performed to understand the corrosion behavior in a spent nuclear fuel reprocessing. In this study, the 9Cr-ODS steel with lower effective chromium content was evaluated to understand the corrosion behavior conservatively. As results, the tube-type specimens of the 9Cr-ODS steels suffered severe weight loss owing to active dissolution at the beginning of the immersion test in pure nitric acid solution inmore » the range from 1 to 3.5 M. In contrast, the weight loss was decreased and they showed a stable corrosion in the higher nitric acid concentration, the dissolved FBR fuel solution, and its simulated solution by passivation. The corrosion rates of the 9Cr-ODS steel in the dissolved FBR fuel solution and its simulated solution were 1-2 mm/y and showed good agreement with each other. The passivation was caused by the shift of corrosion potential to noble side owing to increase in nitric acid concentration or oxidative ions in the dissolved FBR fuel solution and the simulated spent fuel solution. (authors)« less

Effect of carbon and manganese on the microstructure and mechanical properties of 9Cr2WVTa deposited metals

NASA Astrophysics Data System (ADS)

Wang, Jian; Rong, Lijian; Li, Dianzhong; Lu, Shanping

2017-03-01

Six 9Cr2WVTa deposited metals with different carbon and manganese contents have been studied to reveal the role of major elements, which guide for the design of welding consumables for reduced activation ferritic/martensitic steel and meet for the requirements of accelerator driven systems-lead fusion reactors. The typical microstructure for the 9Cr2WVTa deposited metals is the lath martensite along with the fine stripe δ-ferrite. The chemical compositions influence the solidification sequence and therefore, change the δ-ferrite content in the deposited metal. The impact toughness for the 9Cr2WVTa deposited metals decreases remarkably when the δ-ferrite content is more than 5.2 vol%, also the impact toughness decreases owing to the high quenching martensite formation. Increasing the level of manganese addition, α phase of each alloy shifts to the bottom right according to the CCT diagram.

Effects of chromium and aluminum on mechanical and oxidation properties of iron-nickel-base superalloys based on CG-27

NASA Technical Reports Server (NTRS)

Schuon, S. R.

1985-01-01

The effects of chromium and aluminum on the mechanical and oxidation properties of a series of gamma-prime-strengthened alloys based on CG-27 were studied. Gamma-prime dispersion and solid-solution strengthening were the principal modes of alloy strengthening. The oxidation attack parameter K sub a decreased with increasing Cr and Al contents for each alloy group based on Al content. As a group, alloys with 3 wt % Al had the lowest attack parameters. Therefore, 3 wt % is the optimum level of Al for parabolic oxidation behavior. Spalling, due to diffusion-induced grain growth, was controlled by the overall Cr and Al levels. The alloy with 4 wt % Cr and 3 wt % Al had stress-rupture properties superior to those of the base alloy, CG-27, and maintained parabolic oxidation behavior while the Cr content was reduced by two-thirds of its value in cast CG-27.

Pharmacokinetics of pregabalin controlled-release in healthy volunteers: effect of food in five single-dose, randomized, clinical pharmacology studies.

PubMed

Chew, Marci L; Plotka, Anna; Alvey, Christine W; Pitman, Verne W; Alebic-Kolbah, Tanja; Scavone, Joseph M; Bockbrader, Howard N

2014-09-01

The pharmacokinetic properties of the immediate-release (IR) and the recently developed controlled-release (CR) formulation of pregabalin are dose proportional. Pregabalin IR can be taken with or without food. This analysis characterizes the effect of food on pregabalin CR. The objectives of this analysis were: (1) to evaluate the effect of administration time and fat or caloric content of an accompanying meal on the pharmacokinetic properties of a single dose of pregabalin CR (330 mg) relative to a single dose of pregabalin IR (300 mg); (2) to evaluate the pharmacokinetic properties of a single dose of pregabalin CR administered fasted relative to a single dose of pregabalin CR administered immediately after food; and (3) to determine the safety and tolerability of single-dose administration of pregabalin CR and IR with and without food. The effect of food on the pharmacokinetic properties of pregabalin CR was determined in five phase I, open-label, single-dose, crossover studies (24-28 participants/study). Caloric and fat content of meals were varied and treatments were administered in the morning, at midday, or in the evening. Blood samples were collected up to 48 h post-dose. Pharmacokinetic parameters were estimated from plasma concentration-time data using standard noncompartmental methods. Adverse events were monitored throughout all studies. One hundred and twenty-eight healthy participants (19-54 years of age) received pregabalin. Peak plasma concentrations (C max) were lower for CR than the respective pregabalin IR doses, and time to C max occurred later. When pregabalin CR was administered with food at midday or in the evening, total exposures [area under the plasma concentration-time curve from time zero extrapolated to infinite time (AUC∞)] were equivalent for pregabalin CR and IR formulations regardless of fat or caloric content. When pregabalin CR was administered with an 800-1,000 calorie medium-fat breakfast, AUC∞ was equivalent for pregabalin CR and IR. Bioequivalence criteria for comparison of pregabalin CR after a low- or medium-calorie breakfast relative to pregabalin IR were not met; however, bioavailability of the pregabalin CR vs. IR formulation was relatively high (75-86 %). When pregabalin CR was administered fasted, the AUC∞ was 70-78 % of the AUC∞ of pregabalin CR administered with food and bioequivalence criteria were not met. Additionally, the AUC∞ of the pregabalin CR formulation administered fasted was 62-69 % of that of pregabalin IR administered fasted and bioequivalence criteria were not met. Single-dose pregabalin CR and IR were well tolerated in all studies, with no serious or severe adverse events reported. Time of day of administration and the fat and caloric content of the accompanying meal had minimal overall effect on the pharmacokinetic properties and bioavailability of the pregabalin CR formulation.

What is controlling the reflectance spectra (0.35-150 μm) of hydrated (and dehydrated) carbonaceous chondrites?

NASA Astrophysics Data System (ADS)

Beck, Pierre; Maturilli, A.; Garenne, A.; Vernazza, P.; Helbert, J.; Quirico, E.; Schmitt, B.

2018-10-01

In order to determine the controls on the reflectance spectra of hydrated carbonaceous chondrites, reflectance spectra were measured for a series of samples with well-determined mineralogy, water-content, and thermal history. This includes 5 CR chondrites, 11 CM chondrites, and 7 thermally metamorphosed CM chondrites. These samples were characterized over the 0.35-150 μm range by reflectance spectroscopy in order to cover the full spectral range accessible from ground based observation, and that will be determined in the near-future by the Hayabusa-2 and Osiris-REx missions. While spectra show absorption features shortward of 35 μm, no strong absorption bands were identified in this suite of samples longward of 35 μm. This work shows that the 0.7-μm band observed in hydrated carbonaceous chondrites is correlated with the total water content as well as with the band depth at 2.7 μm, confirming the suggestion that they are related to Mg-rich, Fe-bearing phyllosilicates. A feature at 2.3 μm, diagnostic of such phyllosilicates was found for all samples with a detectable 0.7-μm band, also indicative of Mg-rich phyllosilicates. A strong variability is found in the shape of the 3-μm band among CM chondrites, and between CM, CR and thermally metamorphosed CM chondrites. Heavily altered CM chondrites show a single strong band around 2.72 μm while more thermally metamorphosed CM samples show an absorption band at higher wavelength. The CR chondrite GRO 95577 has a 3-μm feature very similar to those of extensively altered CM chondrites while other CR chondrite rather shows goethite-like signatures (possibly due to terrestrial weathering of metals). Thermally metamorphosed CM chondrites all have 3-μm features, which are not purely due to terrestrial adsorbed water. The band shape ranges from heavily altered CM-like to goethite-like. The overall reflectance was found to be significantly higher for CR chondrites than for CM chondrites. This is also true for the hydrated CR chondrite GRO 95577 whose reflectance spectrum is almost identical to spectra obtained for CM chondrites except that it is brighter by about 40% in the visible. Another possibility to distinguish hydrated CM from hydrated CR chondrites is to use the combination of band depths at 0.7 and 2.3 μm. When comparing the spectra obtained with Cg and Cgh spectral end member, it is found that the band depth determined for hydrated chondrites (0.7 and 2.3 μm) are always higher than calculated for these spectral endmembers. If one considers only asteroids with unambiguous hydration detection, band depth at 0.7 μm is of similar value to those measured for hydrated carbonaceous chondrites.

Composition-controlled active-passive transition and corrosion behavior of Fe-Cr(Mo)-Zr-B bulk amorphous steels

NASA Astrophysics Data System (ADS)

Si, Jiajia; Wu, Yidong; Wang, Tan; Liu, Yanhui; Hui, Xidong

2018-07-01

Various corrosive environments in daily life and industry have put forward high requirement on corrosion resistance of metals, especially steels. Unlike the strict demand in Cr content of crystalline stainless steels, amorphous steels (ASs) with lower Cr content can be endowed with outstanding corrosion resistance, while the intrinsic mechanism is not fully understood. Herein, we present a novel Fe92-x-y-zCrxMoyZr8Bz (6 ≤ x ≤ 40, 0 ≤ y ≤ 22, and 12 ≤ z ≤ 18) bulk amorphous steel (BAS) forming system and reveal the synergistic effect of Cr and Mo in determining the chemical stability of oxide films. It has been found the Fe92-x-zCrxZr8Bz BASs with 1 mm in diameter display a Cr-controlling active-passive transition at the Cr threshold of ∼25% in 1 M hydrochloric acid. When adding minor Mo into the BASs, the Cr threshold can be remarkably reduced by forming favorable hexavalent Mo oxides. The generation of Mo6+ is facilitated by atomic selective dissolution at the interface and can promote the passivation. In contrast, when the Cr content of the Mo-doped glasses exceeds 25%, few Mo6+ oxides would produce as the prior formation of protective passive films inhibits the further oxidation of Mo. Therefore, manipulating the active-passive transition properly is crucial to designing ASs with high stainlessness.

Creatine uptake in mouse hearts with genetically altered creatine levels

PubMed Central

Hove, Michiel ten; Makinen, Kimmo; Sebag-Montefiore, Liam; Hunyor, Imre; Fischer, Alexandra; Wallis, Julie; Isbrandt, Dirk; Lygate, Craig; Neubauer, Stefan

2008-01-01

Creatine plays an important role in energy metabolism in the heart. Cardiomyocytes accumulate creatine via a specific creatine transporter (CrT), the capacity of which is reduced in the failing heart, resulting in lower myocardial creatine concentration. Therefore, to gain insight into how the CrT is regulated, we studied two mouse models of severely altered myocardial creatine levels. Cardiac creatine uptake levels were measured in isolated hearts from creatine-free guanidinoacetate-N-methyl transferase knock out (GAMT−/−) mice and from mice overexpressing the myocardial CrT (CrT-OE) using 14C-radiolabeled creatine. CrT mRNA levels were measured using real time RT-PCR and creatine levels with HPLC. Hearts from GAMT−/− mice showed a 7-fold increase in Vmax of creatine uptake and a 1.4-fold increase in CrT mRNA levels. The increase in Cr uptake and in CrT mRNA levels, however, was almost completely prevented when mice were fed a creatine supplemented diet, indicating that creatine uptake is subject to negative feedback regulation. Cardiac creatine uptake levels in CrT-OE mice were increased on average 2.7-fold, showing a considerable variation, in line with a similar variation in creatine content. Total CrT mRNA levels correlated well with myocardial creatine content (r = 0.67; p < 0.0001) but endogenous CrT mRNA levels did not correlate at all with myocardial creatine content (r = 0.01; p = 0.96). This study shows that creatine uptake can be massively upregulated in the heart, by almost an order of magnitude and that this upregulation is subject to feedback inhibition. In addition, our results strongly suggest that CrT activity is predominantly regulated by mechanisms other than alterations in gene expression. PMID:18602925

Study on the prediction of soil heavy metal elements content based on visible near-infrared spectroscopy.

PubMed

Liu, Jinbao; Zhang, Yang; Wang, Huanyuan; Du, Yichun

2018-06-15

The estimation of soils heavy metal content can reflect the impending surroundings of surface, which lays theoretical foundation for using covered vegetation to monitor environment and investigate resource. In this study, the contents of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb in 44 soil samples were collected from Fufeng County, Yangling County and Wugong County, Shaanxi Province and were used as data sources. ASD FieldSpec HR (350-2500nm), and then the NOR, MSC and SNV of the reflectance were pretreated, the first deviation, second deviation and reflectance reciprocal logarithmic transformation were carried out. The optimal spectroscopy estimation model of nine heavy metal elements of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb was established by regression method. Comparing the diffuse reflectance characteristics of different heavy metal contents and the effect of different pretreatment methods on the establishment of soil heavy metal spectral inversion model. The results of chemical analysis show that there was a serious Hg pollution in the study area, and the Cd content was close to the critical value. The results show that: (1) NOR, MSC and SNV were adopted for the acquisition of visible near-infrared. Combining differential transformation can improve the information of heavy metal elements in the soil, and use the correlation band energy Significantly improve the stability and predictability of the model. (2) The modeling accuracy of the optimal model of nine heavy metal spectra of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb by PLSR method were 0.70, 0.79, 0.69, 0.81, 0.86, 0.58, 0.55, 0.99, 0.62. (3) The optimal estimation model of different elements using different treatment methods has better stability and higher precision, and can realize the rapid prediction of nine kinds of heavy metal elements in this region. Copyright © 2018 Elsevier B.V. All rights reserved.

Study on the prediction of soil heavy metal elements content based on visible near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Liu, Jinbao; Zhang, Yang; Wang, Huanyuan; Du, Yichun

2018-06-01

The estimation of soils heavy metal content can reflect the impending surroundings of surface, which lays theoretical foundation for using covered vegetation to monitor environment and investigate resource. In this study, the contents of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb in 44 soil samples were collected from Fufeng County, Yangling County and Wugong County, Shaanxi Province and were used as data sources. ASD FieldSpec HR (350-2500 nm), and then the NOR, MSC and SNV of the reflectance were pretreated, the first deviation, second deviation and reflectance reciprocal logarithmic transformation were carried out. The optimal spectroscopy estimation model of nine heavy metal elements of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb was established by regression method. Comparing the diffuse reflectance characteristics of different heavy metal contents and the effect of different pretreatment methods on the establishment of soil heavy metal spectral inversion model. The results of chemical analysis show that there was a serious Hg pollution in the study area, and the Cd content was close to the critical value. The results show that: (1) NOR, MSC and SNV were adopted for the acquisition of visible near-infrared. Combining differential transformation can improve the information of heavy metal elements in the soil, and use the correlation band energy Significantly improve the stability and predictability of the model. (2) The modeling accuracy of the optimal model of nine heavy metal spectra of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb by PLSR method were 0.70, 0.79, 0.69, 0.81, 0.86, 0.58, 0.55, 0.99, 0.62. (3) The optimal estimation model of different elements using different treatment methods has better stability and higher precision, and can realize the rapid prediction of nine kinds of heavy metal elements in this region.

Vermicomposting as an advanced biological treatment for industrial waste from the leather industry.

PubMed

Nunes, Ramom R; Bontempi, Rhaissa M; Mendonça, Giovane; Galetti, Gustavo; Rezende, Maria Olímpia O

2016-01-01

The leather industry (tanneries) generates high amounts of toxic wastes, including solid and liquid effluents that are rich in organic matter and mineral content. Vermicomposting was studied as an alternative method of treating the wastes from tanneries. Vermicompost was produced from the following tannery residues: tanned chips of wet-blue leather, sludge from a liquid residue treatment station, and a mixture of both. Five hundred earthworms (Eisenia fetida) were added to each barrel. During the following 135 days the following parameters were evaluated: pH, total organic carbon (TOC), organic matter (OM), cation exchange capacity (CEC), C:N ratio, and chromium content as Cr (III) and Cr (VI). The results for pH, TOC and OM contents showed decreases in their values during the composting process, whereas values for CEC and total nitrogen rose, indicating that the vermicompost reached maturity. For chromium, at 135 days, all values of Cr (VI) were below the detectable level. Therefore, the Cr (VI) content had probably been biologically transformed into Cr (III), confirming the use of this technique as an advanced biological treatment. The study reinforces the idea that vermicomposting could be introduced as an effective technology for the treatment of industrial tannery waste and the production of agricultural inputs.

Effect of Alloying Additions on Oxidation Behaviors of Ni-Fe Based Superalloy for Ultra-Supercritical Boiler Applications

NASA Astrophysics Data System (ADS)

Lu, Jintao; Yang, Zhen; Zhao, Xinbao; Yan, Jingbo; Gu, Y.

A new kind of Ni-Fe-based superalloy is designed recently for 750 °C-class A-USC boiler tube. The oxidation behavior of the designed alloys with various combinations of anti-oxidation additions, Cr, Al and Si, was investigated at 750 °C and 850 °C, respectively. The results indicated that the oxidation rate of tested alloys decreased with the increase of the sum of additions. Cr addition may drop the relative constant of parabolic rate greatly when temperature is raised. But the oxide scale, mainly consisted of NiCr spinel at 750 °C and NiCrMn spinel at 850 °C, was similar while the Cr content is in a range of 20-25 wt.% at tested temperatures. Al addition, however, showed the best effective to reduce the oxidation rates. Internal Al-rich oxide was observed at the scale/metal interface for alloys added with high content of Al and was increased with Al content increase. Very tiny difference between the oxide scales of the Si-added alloys was identified when Si content varies among 0.02-0.05 wt.%. Basing on these results, this presentation discussed the optimum combination of anti-oxidation additions as well as oxidation mechanisms in the designed Ni-Fe-base superalloy.

A comparative study of health risk of potentially toxic metals in urban and suburban road dust in the most populated city of China

NASA Astrophysics Data System (ADS)

Shi, Guitao; Chen, Zhenlou; Bi, Chunjuan; Wang, Li; Teng, Jiyan; Li, Yuansheng; Xu, Shiyuan

2011-01-01

Urban and suburban road dust samples were collected in the most populated city of China, Shanghai. Size fractions of dust particles were analyzed; metal levels of the dust were also measured. Human exposure to individual toxic metals through road dust was assessed for both children and adults. The results showed that dust particles from urban and suburban road were presented similar size distribution pattern, with most particles in the range of 100-400 μm. Urban road dust consisted of higher proportions of inhalable, thoracic and respirable particles with increased risk of adverse effects to human. In general, mean grain sizes of urban road dust were smaller than suburban dust. Total organic carbon contents and levels of Pb, Cd, Cu, Zn, Ni, Cr in urban dust were higher than those of suburban dust. But the concentrations of As and Hg from suburban dust were higher, indicting a different main source. The exposure pathway which resulted in the highest level of risk for human exposed to road dust was ingestion of this material, which was followed by dermal contact. Except for some locations, risk values of both cancer and non-cancer obtained in this study were in the receivable range on the whole. Children had greater health risks than adults. The overall risks of non-cancer in urban area were higher than those in suburban area, but the values of cancer in the two areas were comparable. As for the aggregate noncarcinogenic risk, Pb was of most concern regarding the potential occurrence of health impacts. Of the three carcinogenic metals As, Cr and Cd, the only mean risk higher than 10 -6 was Cr, accounting for a great percentage (95%) of the overall risk of cancer. Hence, potentially adverse health effects arising from Pb and Cr in road dust should arouse wide concern.

Potentially toxic elements in foodcrops: Triticum aestivum L., Zea mays L.

NASA Astrophysics Data System (ADS)

Bini, Claudio; Fontana, Silvia; Squizzato, Stefania; Minello, Fabiola; Fornasier, Flavio; Wahsha, Mohammad

2013-04-01

Soil is the basis of the ecosystems and of our system of food production. Crops can uptake heavy metals and potentially toxic elements from the soil and store them in the roots or translocate them to the aerial parts. Excessive content of these elements in edible parts can produce toxic effects and, through the food chain and food consumption, result in a potential hazard for human health. In this study soils and plants (spring wheat, Triticum aestivum L. and maize, Zea mays L.) from a tannery district in North-East Italy were analyzed to determine pedological characters, soil microbial indicators and the content of some major and micro-nutrients and potentially toxic elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S, Zn, V). The soils of the area are moderately polluted; Cr is the most important inorganic contaminant, followed by Ni, Cu and V. Factor analysis evidenced that the contaminants are in part anthropogenic and in part geogenic. Major anthropogenic origin was detected for Cr, Ni (from industrial activities), Zn, Cu, Cd (from agriculture practices). Biological Absorption Coefficient (BAC) from soil to plant roots and Translocation factor (TF) within the plant were calculated; major nutrients (K, P, S) and some micronutrients (Cu, Zn, Mg, Mn) are easily absorbed and translocated, whilst other nutrients (Ca, Fe) and potentially toxic elements or micronutrients (Al, Cd, Cr, Ni, Pb, V) are not accumulated in the seeds of the two considered species. However, the two edible species proved differently able to absorb and translocate elements, and this suggests to consider separately every species as potential PHEs transporter to the food chain and to humans. Cr concentrations in seeds and other aerial parts (stem and leaves) of the examined plants are higher than the values found for the same species and for other cereals grown on unpolluted soils. Comparing the Cr levels in edible parts with recommended dietary intake, besides other possible Cr sources (dust ingestion, water), there seems to be no health risk for animal breeding and population due to the consumption of wheat and maize grown in the area.

Enhanced photodegradation activity of methyl orange over Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites under visible light irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin

Highlights: • Novel visible-light-driven Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites are synthesized. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits higher photocatalytic activity than pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits excellent stability for the photodegradation of MO. • The possible photocatalytic mechanism was discussed in detail. - Abstract: Novel Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites were prepared by a simple chemical precipitation method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The visible light photocatalytic tests showed that the Ag{sub 2}CrO{sub 4}/SnS{sub 2} compositesmore » enhanced photocatalytic activities for the photodegradation of methyl orange (MO) under visible light irradiation (λ > 420 nm), and the optimum rate constant of Ag{sub 2}CrO{sub 4}/SnS{sub 2} at a weight content of 1.0% Ag{sub 2}CrO{sub 4} for the degradation of MO was 2.2 and 1.5 times larger than that of pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}, respectively. The improved activity could be attributed to high separation efficiency of photogenerated electrons-hole pairs on the interface of Ag{sub 2}CrO{sub 4} and SnS{sub 2}, which arised from the synergistic effect between Ag{sub 2}CrO{sub 4} and SnS{sub 2}. Moreover, the possible photocatalytic mechanism with superoxide radical anions and holes species as the main reactive species in photocatalysis process was proposed on the basis of experimental results.« less

The effect of O2 content on the corrosion behaviour of X65 and 5Cr in water-containing supercritical CO2 environments

NASA Astrophysics Data System (ADS)

Hua, Yong; Barker, Richard; Neville, Anne

2015-11-01

The general and localized corrosion behaviour of X65 carbon steel and 5Cr low alloy steel were evaluated in a water-saturated supercritical CO2 environment in the presence of varying concentrations of O2. Experiments were performed at a temperature of 35 °C and a pressure of 80 bar to simulate the conditions encountered during CO2 transport and injection. Results indicated that increasing O2 concentration from 0 to 1000 ppm caused a progressive reduction in the general corrosion rate, but served to increase the extent of localized corrosion observed on both materials. Pitting (or localized attack) rates for X65 ranged between 0.9 and 1.7 mm/year, while for 5Cr rose from 0.3 to 1.4 mm/year as O2 concentration was increased from 0 to 1000 ppm. General corrosion rates were over an order of magnitude lower than the pitting rates measured. Increasing O2 content in the presence of X65 and 5Cr suppressed the growth of iron carbonate (FeCO3) on the steel surface and resulted in the formation of a corrosion product consisting mainly of iron oxide (Fe2O3). 5Cr was shown to offer more resistance to pitting corrosion in comparison to X65 steel over the conditions tested. At concentrations of O2 above 500 ppm 5Cr produced general corrosion rates less than 0.04 mm/year, which were half that recorded for X65. The improved corrosion resistance of 5Cr was believed to be at least partially attributed to the formation of a Cr-rich film on the steel surface which was shown using X-ray photoelectron spectroscopy to contain chromium oxide (Cr2O3) and chromium hydroxide (Cr(OH)3). A final series of tests conducted with the addition of 1000 ppm O2 in under-saturated conditions (water content below solubility limit) revealed that no corrosion was observed when the water content was below 1200 ppm for both materials.

Effect of 6-Month Calorie Restriction and Exercise on Serum and Liver Lipids and Markers of Liver Function

PubMed Central

Larson-Meyer, D. Enette; Newcomer, Bradley R.; Heilbronn, Leonie K.; Volaufova, Julia; Smith, Steven R.; Alfonso, Anthony J.; Lefevre, Michael; Rood, Jennifer C.; Williamson, Donald A.; Ravussin, Eric

2009-01-01

objective Nonalcoholic fatty liver disease (NAFLD) and its association with insulin resistance are increasingly recognized as major health burdens. The main objectives of this study were to assess the relation between liver lipid content and serum lipids, markers of liver function and inflammation in healthy overweight subjects, and to determine whether caloric restriction (CR) (which improves insulin resistance) reduces liver lipids in association with these same measures. Methods and Procedures Forty-six white and black overweight men and women (BMI = 24.7-31.3 kg/m2) were randomized to “control (CO)” = 100% energy requirements; “CR” = 25%; “caloric restriction and increased structured exercise (CR+EX)”= 12.5% CR + 12.5% increase in energy expenditure through exercise; or “low-calorie diet (LCD)” = 15% weight loss by liquid diet followed by weight-maintenance, for 6 months. Liver lipid content was assessed by magnetic resonance spectroscopy (MRS) and computed tomography (CT). Lipid concentrations, markers of liver function (alanine aminotransferase (ALT), alkaline phosphatase (ALK)), and whole-body inflammation (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP)) were measured in fasting blood. Results At baseline, increased liver lipid content (by MRS) correlated (P < 0.05) with elevated fasting triglyceride (r = 0.52), ALT (r = 0.42), and hsCRP (r = 0.33) concentrations after adjusting for sex, race, and alcohol consumption. With CR, liver lipid content was significantly lowered by CR, CR+EX, and LCD (detected by MRS only). The reduction in liver lipid content, however, was not significantly correlated with the reduction in triglycerides (r = 0.26; P = 0.11) or with the changes in ALT, high-density lipoprotein (HDL)-cholesterol, or markers of whole-body inflammation. Discussion CR may be beneficial for reducing liver lipid and lowering triglycerides in overweight subjects without known NAFLD. PMID:18421281

Influence of the thermodynamic parameters on the temper embrittlement of SA508 Gr.4N Ni-Cr-Mo low alloy steel with variation of Ni, Cr and Mn contents

NASA Astrophysics Data System (ADS)

Park, Sang-Gyu; Lee, Ki-Hyoung; Min, Ki-Deuk; Kim, Min-Chul; Lee, Bong-Sang

2012-07-01

It is well known that SA508 Gr.4N low alloy steel offers improved fracture toughness and strength compared to commercial low alloy steels such as SA508 Gr.3 Mn-Mo-Ni low alloy steel. In this study, the effects of Cr, Mn, and Ni on temper embrittlement in SA508 Gr.4N low alloy steel were evaluated from the viewpoint of thermodynamic parameters such as P diffusivity and C activity. The changes of the ductile-brittle transition temperatures before and after aging were correlated with varying alloying element content, and the diffusivity of P and the activity of C were calculated and correlated with the transition behaviors. The addition of Ni, Cr, and Mn reduce the resistance to temper embrittlement, showing increased Transition-Temperature Shift (TTS) and an increased fraction of intergranular fracture. Although the diffusivity of P is changed by the addition of alloying elements, it does not considerably affect the temper embrittlement. The Mn and Cr content in the matrix significantly reduce the C activity, with showing an inversely proportional relationship to TTS. The change of susceptibility to temper embrittlement caused by Cr and Mn addition could be explained by the variation of C activity. Unlike Cr and Mn, Ni has little effect on the temper embrittlement and C activity.

Chromium and iron content in duplicate meals at a university residence: daily intake and dialysability.

PubMed

Cabrera-Vique, Carmen; Mesías, Marta

2011-05-01

The objective of the present study was to determine total Cr and Fe content and the corresponding mineral dialysable fraction in a total of sixty-three duplicate meals. Samples of breakfast, lunch and dinner were taken over twenty-one consecutive days at a female university residence in Granada (Spain). Cr content in the duplicate daily meals ranged from 98·50 to 120·80 μg, with a mean of 110·00 μg, and Fe levels ranged from 9·50 to 40·00 mg, with a mean content of 18·50 mg. The mean Cr and Fe dialysable fractions ranged from 0·50 to 1·50 % and from 7·75 to 11·80 %, respectively. Possible correlations with energy and other nutrient intakes were also evaluated. Adherence of the meals to the Mediterranean dietary patterns was tested, and these findings reveal that a balanced and varied diet based on a Mediterranean-style diet plan provides adequate levels and bioaccessibility of Cr and Fe for young women, which is especially important to avoid mineral deficiencies.

Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

NASA Astrophysics Data System (ADS)

Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

2016-12-01

Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

Mobility of as, Cu, Cr, and Zn from tailings covered with sealing materials using alkaline industrial residues: a comparison between two leaching methods.

PubMed

Jia, Yu; Maurice, Christian; Öhlander, Björn

2016-01-01

Different alkaline residue materials (fly ash, green liquor dregs, and lime mud) generated from the pulp and paper industry as sealing materials were evaluated to cover aged mine waste tailings (<1% sulfur content, primarily pyrite). The mobility of four selected trace elements (Cr, Cu, Zn, and As) was compared based on batch and column leaching studies to assess the effectiveness of these alkaline materials as sealing agents. Based on the leaching results, Cr, Cu, and Zn were immobilized by the alkaline amendments. In the amended tailings in the batch system only As dramatically exceeded the limit values at L/S 10 L/kg. The leaching results showed similar patterns to the batch results, though leached Cr, Cu, and Zn showed higher levels in the column tests than in the batch tests. However, when the columns were compared with the batches, the trend for Cu was opposite for the unamended tailings. By contrast, both batch and column results showed that the amendment caused mobilization of As compared with the unamended tailings in the ash-amended tailings. The amount of As released was greatest in the ash column and decreased from the dregs to the lime columns. The leaching of As at high levels can be a potential problem whenever alkaline materials (especially for fly ash) are used as sealing materials over tailings. The column test was considered by the authors to be a more informative method in remediation of the aged tailings with low sulfur content, since it mimics better actual situation in a field.

Phytoaccumulation and phytotoxicity of cadmium and chromium in duckweed Wolffia globosa.

PubMed

Boonyapookana, Benjaporn; Upatham, E Suchart; Kruatrachue, Maleeya; Pokethitiyook, Prayad; Singhakaew, Sombat

2002-01-01

The phytoaccumulation and phytotoxicity of heavy metals, cadmium (Cd), and chromium (Cr) on a common duckweed, Wolffia globosa, were studied. W. globosa were cultured in 3% Hoagland's nutrient medium, which was supplemented with 1, 2, 4, and 8 mg/L of Cd and Cr and were separately harvested after 3, 6, 9, and 12 days. The accumulation of Cd and Cr in W. globosa showed significant increases when the exposure time and metal concentration were increased. The effects of Cd and Cr on the biomass productivity and total chlorophyll content in W. globosa indicated that there were significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased.

Effects of Oral Administration of CrCl3 on the Contents of Ca, Mg, Mn, Fe, Cu, and Zn in the Liver, Kidney, and Heart of Chicken.

PubMed

Liu, Yanhan; Zhao, Xiaona; Zhang, Xiao; Zhao, Xuejun; Liu, Yongxia; Liu, Jianzhu

2016-06-01

This study aimed to investigate the effects of oral administration of trivalent chromium on the contents of Ca, Mg, Mn, Fe, Cu, and Zn in the heart, liver, and kidney. Different levels of 1/8, 1/4, and 1/2 LD50 (LD50 = 5000 mg/kg body mass) CrCl3 milligrams per kilogram body mass daily were added into the water to establish the chronic poisoning model. Ca, Mg, Mn, Fe, Cu, and Zn were detected with the flame atomic absorption spectrometry in the organs exposed 14, 28, and 42 days to CrCl3, respectively. Results showed that Cr was accumulated in the heart, liver, and kidney significantly (P < 0.05) with extended time and dose. The contents of Ca and Fe increased, whereas those of Mg, Mn, Cu, and Zn decreased in the heart, liver, and kidney of each treated group, which had a dose- and time-dependent relationship, but the contents of Mg and Zn in the heart took on a fluctuated change. These particular observations were different from those in the control group. In conclusion, the oral administration of CrCl3 could change the contents of Ca, Mg, Mn, Fe, Cu, and Zn in the heart, liver, and kidney, which may cause disorders in the absorption and metabolism of the metal elements of chickens.

Oxidation studies of Fe10CrAl-RE alloys exposed to Pb at 550 °C for 10,000 h

NASA Astrophysics Data System (ADS)

Ejenstam, Jesper; Halvarsson, Mats; Weidow, Jonathan; Jönsson, Bo; Szakalos, Peter

2013-11-01

Five experimental FeCrAl-RE alloys have been exposed up to 10,000 h in stagnant liquid Pb at 550 °C. The test matrix consisted of three 10 wt.% Cr alloys, with an Al content ranging from 4 to 8 wt.% (10Cr-4Al, 10Cr-6Al and 10Cr-8Al), one alloy without additions of reactive elements (RE) (10Cr-6Al), and one reference alloy with 21 wt.% Cr and 5 wt.% Al (21Cr-5Al). The evaluation showed a clear difference in oxidation properties, and it was possible to divide the alloys into two distinct groups. A critical Al concentration in the interval of 4-6 wt.% at the given RE content was required to form a thin protective oxide. However, the absence of RE addition in one of the two 10Cr-6Al alloys resulted in a significant reduction in oxidation resistance, comparable with 10Cr-4Al. None of the alloys were severely corroded, however Pb penetrated to a relatively large extent into the porous oxide of the low performing alloys. A 100 nm thick oxide scale, partly consisting of alumina (Al2O3), was observed for the high performing 10Cr-6Al alloy. The Fe10CrAl-RE alloys showed overall very good corrosion resistance and are hence a promising new alloy category for liquid Pb applications.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals.

PubMed

Liu, Siyuan; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing; Zhu, Jie

2018-01-31

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

Effects of Some Light Alloying Elements on the Oxidation Behavior of Fe and Ni-Cr Based Alloys During Air Plasma Spraying

NASA Astrophysics Data System (ADS)

Zeng, Zhensu; Kuroda, Seiji; Kawakita, Jin; Komatsu, Masayuki; Era, Hidenori

2010-01-01

The oxidation behavior of iron binary powders with addition of Si (1, 4 wt.%) and B (1, 3 wt.%) and that of a Ni-Cr based alloy powder with Si (4.3 wt.%), B (3.0 wt.%), and C (0.8 wt.%) additions during atmosphere plasma spray (APS) have been investigated. Analysis of the chemical composition and phases of oxides in the captured in-flight particles and deposited coatings was carried out. The results show that the addition of Si and B to iron effectively reduced the oxygen contents in the coatings, especially during the in-flight period at higher particles temperature. Ni-Cr based alloy powder with Si, B, and C additions reduced the oxidation of the base alloys significantly. Preferential oxidation and subsequent vaporization of Si, B, and C from the surface of the sprayed particles are believed to play a major role in controlling oxidation in the APS process.

Corrosion behavior of low alloy steels in a wet-dry acid humid environment

NASA Astrophysics Data System (ADS)

Zhao, Qing-he; Liu, Wei; Yang, Jian-wei; Zhu, Yi-chun; Zhang, Bin-li; Lu, Min-xu

2016-09-01

The corrosion behavior of corrosion resistant steel (CRS) in a simulated wet-dry acid humid environment was investigated and compared with carbon steel (CS) using corrosion loss, polarization curves, X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), N2 adsorption, and X-ray photoelectron spectroscopy (XPS). The results show that the corrosion kinetics of both steels were closely related to the composition and compactness of the rust, and the electrochemical properties of rusted steel. Small amounts of Cu, Cr, and Ni in CRS increased the amount of amorphous phases and decreased the content of γ-FeOOH in the rust, resulting in higher compactness and electrochemical stability of the CRS rust. The elements Cu, Cr, and Ni were uniformly distributed in the CRS rust and formed CuFeO2, Cu2O, CrOOH, NiFe2O4, and Ni2O3, which enhanced the corrosion resistance of CRS in the wet-dry acid humid environment.

Use of high metal-containing biogas digestates in cereal production - Mobility of chromium and aluminium.

PubMed

Dragicevic, Ivan; Eich-Greatorex, Susanne; Sogn, Trine A; Horn, Svein J; Krogstad, Tore

2018-07-01

Biogas digestate use as organic fertilizer has been widely promoted in recent years as a part of the global agenda on recycling waste and new sustainable energy production. Although many studies have confirmed positive effects of digestates on soil fertility, there is still lack of information on the potential adverse effects of digestates on natural soil heavy metal content, metal leaching and leaching of other pollutants. We have investigated the release of aluminium (Al) and chromium (Cr) from different soils treated with commercial digestates high in mentioned potentially problematic metals in a field experiment, while a greenhouse and a laboratory column experiment were used to address mobility of these metals in two other scenarios. Results obtained from the field experiment showed an increase in total concentrations for both investigated metals on plots treated with digestates as well as a significant increase of water-soluble Al concentrations. Factors that were found to be mostly affecting the metal mobility were dissolved organic carbon (DOC), pH and type of soil. Metal binding and free metal concentrations were modelled using the WHAM 7.0 software. Results indicated that the use of digestates with high metal content are comparable to use of animal manure with respect to metal leaching. Data obtained through chemical modelling for the samples from the field experiment suggested that an environmental risk from higher metal mobility has to be considered for Al. In the greenhouse experiment, measured concentrations of leached Cr at the end of the growing season were low for all treatments, while the concentration of leached Al from digestates was higher. The high irrigation column leaching experiment showed an increased leaching rate of Cr with addition of digestates. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relationship between heavy metal accumulation and morphometric parameters in European hare (Lepus europaeus) inhabiting various types of landscapes in southern Poland.

PubMed

Wajdzik, Marek; Halecki, Wiktor; Kalarus, Konrad; Gąsiorek, Michał; Pająk, Marek

2017-11-01

To evaluate the influence of hazardous substances in the environment, studies of pollutant accumulation in wild living animals are needed. Studies dealing with heavy metal contamination in mammals usually focus on a single organ. We investigated accumulation of heavy metals as well as iron in European hare (Lepus europaeus) living in southern Poland, Małopolska Province. Hares were captured during the hunting season. We tested metal accumulation in 14 organs and tissues using 35 individuals with known body weight and sex inhabiting agricultural, industrial and other types of landscapes. To obtain deeper insight into contamination patterns, we used accumulation data from the liver since it is the most frequently investigated organ and prone to pollution accumulation. Based on the data obtained for the liver, we tested the impact of metal pollution on hare morphology, including body length and several skull cranimetric parameters. Metals content differed between organs. Moreover, individuals from industrial areas had higher Cd content in their body. We distinguished two groups of elements: the first group, Cd, Fe and Zn, revealed the highest toxic effect in the liver and kidneys; the second group, Cr, Ni, and Pb, accumulated primarily in the brain. Hares inhabiting industrial areas had higher concentration of Cd and Pb, and lower levels of Cr and Fe in their liver in comparison with those from agricultural and forest habitats. Heavy metals had an effect on body length that was negatively associated with Cr levels. Skull diastema length was associated positively with accumulation of Cd and Pb. We showed that hare organs and tissues could be used as bioindicators of environmental pollution by heavy metals. Copyright © 2017 Elsevier Inc. All rights reserved.

[The regulation mechanism of protein kinase Cδ on arsenic liver injury caused by coal-burning].

PubMed

Hu, Yong; Zhang, Ai-hua; Yao, Mao-lin; Tang, Xu-dong; Huang, Xiao-xin

2013-09-01

To investigate the effects of mRNA transcriptional and protein expressions of protein kinase Cδ (PKCδ) on the development of arsenic liver injury caused by coal-burning. Population study:133 arsenic exposures were selected as arsenic exposure groups including the ward non-patient group (25 cases) , no obvious hepatopathy group (38 cases) , mild (43 cases) and moderate to severe hepatopathy group (27 cases) from the area with endemic arsenism in Guizhou province. Another 34 healthy residents were selected as the control group in non-arsenic pollution village. The urine and peripheral blood were collected from the subjects. The arsenic contents in urine and mRNA expressions of PKCδ in peripheral blood were detected. Animal experiment study:thirty wistar rats were randomly by random number table divided into control group, drinking water arsenic poisoning group and coal-burning arsenic poisoning group (i.e., low, medium and high arsenic contaminated grain group) by random number table method, including 6 rats in each group. The control group was fed normally for 3 months, drinking water arsenic poisoning group and coal-burning arsenic poisoning groups were fed respectively with 10 mg/kg As2O3 solution and different concentrations (25, 50 and 100 mg/kg) of arsenic-containing feed which was persisted 3 months. The arsenic contents in urine, mRNA expression levels of PKCδ in peripheral blood and liver tissue and the protein expression levels of phosphorylated protein kinase Cδ(pPKCδ) in liver tissue were detected. The median(quartile) of arsenic contents in urine were 25.58 (18.62-40.73), 56.66 (38.93-76.77), 64.90 (39.55- 98.37) and 75.47 (41.30-109.70) µg/g Cr respectively for the non-patient group, no obvious hepatopathy group, mild and moderate to severe hepatopathy group. The levels were higher than that in the control group (23.34 (17.84-37.45) µg/g Cr) (P < 0.05), except for the ward non-patient group. The arsenic contents in rat urine were 2223.61 (472.98-3976.73), 701.16 (194.01-1300.27), 1060.94 (246.33-2585.47) and 3101.11 (1919.97-5407.07) µg/g Cr, respectively for the drinking water arsenic poisoning group, the low, medium and high dosage arsenic grain contamination groups, all higher than that in the control group (94.32 (22.65-195.25) µg/g Cr) (P < 0.05) . The protein expressions of pPKCδ in liver tissue were 324.83 ± 25.06, 278.50 ± 30.57, 308.83 ± 34.67 and 326.33 ± 35.09, which were significantly higher than that in the control group (240.17 ± 28.07) (P < 0.05) . The protein expression levels of pPKCδ in liver cell membrane were 0.49 ± 0.06,0.33 ± 0.05,0.37 ± 0.06 and 0.50 ± 0.08, which were significantly higher than that in the control group (0.28 ± 0.04) (P < 0.05) . The protein expression levels of pPKCδ in liver cell cytoplasm were 0.38 ± 0.06,0.31 ± 0.05, 0.35 ± 0.05 and 0.36 ± 0.05, which were significantly higher than that in the control group (0.24 ± 0.05) (P < 0.05). The arsenic may regulate protein expressions of pPKCδ and induce its membrane translocation, and cause the development of arsenic liver injury caused by coal-burning.

Comparison of Mineral Element Content in a Functional Food Maca (Lepidium meyenii Walp.) from Asia and South America.

PubMed

Zhang, Ji; Wang, Han-Mo; Zhao, Yan-Li; Zuo, Zhi-Tian; Wang, Yuan-Zhong; Jin, Hang

2015-01-01

Contents of eight mineral elements in maca (Lepidium meyenii Walp.) from China and Peru were determined by inductively coupled plasma optical emission spectroscopy. Cu contents in maca samples from China (2.5-31 mg kg(-1) dry weight, dw) were higher than the samples from Peru (<2.1 mg kg(-1) dw). Na in two samples from China was found to be significantly of high content (2400 and 2600 mg kg(-1) dw). The contents (mg kg(-1) dw) of B, Co, Cr, Li, Ni, and Zn were, respectively, 8.1-21, <0.023, <1.1~3.5, 0.020-0.17, 0.085-4.5, and 10-39 for the samples from China, while being 6.6-12, <0.023, <1.1~2.3, 0.035-0.063, 0.68-1.7, and 27-39 for the samples from Peru.

Assessment of the physical properties and stability of mixtures of tetracycline hydrochloride ointment and acyclovir cream.

PubMed

Inoue, Yutaka; Furuya, Kayoko; Maeda, Rikimaru; Murata, Isamu; Kanamoto, Ikuo

2013-04-15

In dermatology, ointments are often mixed as part of drug therapy, but mixing often leads to incompatibility. Three combinations of tetracycline ointment (TC-o) and acyclovir cream (ACV-cr) were prepared at a TC-o:ACV-cr ratio of 1:1 using a brand-name ACV-cr and two generic ACV-cr (samples TC-o+ACV-A, TC-o+ACV-B, and TC-o+ACV-C). Microscopic examination revealed separation in TC-o+ACV-C. Viscosity and elasticity measurement indicated that the storage modulus (G') and loss modulus (G″) of each of the TC-o+ACV-cr mixtures behaved similarly to those of an ACV-cr and the loss tangent (tanδ) behaved similarly to that of a TC ointment. In addition, differences in the storage modulus (G') and loss modulus (G″) of the TC-o+ACV-cr mixtures were noted. To assess stability, each TC-o+ACV-cr mixture was stored away from direct sunlight at 25 °C and an RH of 84% and at 4 °C (in a refrigerator). HPLC revealed that the ACV content in each TC-o+ACV-cr mixture remained at 95-105% for up to 14 days under both sets of storage conditions. A decline in TC content in each TC-o+ACV-cr mixture was not noted with storage at 4 °C but was noted over time with storage at 25 °C and an RH of 84%. In addition, significant differences in the percent decline in TC content in each TC-o+ACV-cr mixture occurred with storage at 25 °C and an RH of 84%. Thus, differences in physical properties and stability may occur when combining brand-name and generic drugs, and temperature and humidity may be the cause of the TC-o's incompatibility. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

A preliminary investigation of high dose ion irradiation response of a lanthana-bearing nanostructured ferritic steel processed via spark plasma sintering

NASA Astrophysics Data System (ADS)

Pasebani, Somayeh; Charit, Indrajit; Guria, Ankan; Wu, Yaqiao; Burns, Jatuporn; Butt, Darryl P.; Cole, James I.; Shao, Lin

2017-11-01

A nanostructured ferritic steel with nominal composition of Fe-14Cr-1Ti-0.3Mo-0.5La2O3 (wt.%) was irradiated with Fe+2 ions at 475 °C for 100, 200, 300 and 400 dpa. Grain coarsening was observed for the samples irradiated for 200-400 dpa resulting in an increase of the average grain size from 152 nm to 620 nm. Growth of submicron grains at higher radiation doses is due to decreased pinning effect imparted by Cr-O rich nanoparticles (NPs) that underwent coarsening via Ostwald ripening. Dislocation density consistently increased with increasing irradiation dose at 300 and 400 dpa. The mean radius of lanthanum-containing nanoclusters (NCs) decreased and their number density increased above 200 dpa, which is likely due to solutes ejection caused by ballistic dissolution and irradiation-enhanced diffusion. Chromium, titanium, oxygen and lanthanum content of nanoclusters irradiated at 200 dpa and higher got reduced by almost half the initial value. The reduction in size of the nanoclusters accompanied with their higher number density and higher dislocation density led to significant radiation hardening with increasing irradiation dose.

The effect of EDTA on Helianthus annuus uptake, selectivity, and translocation of heavy metals when grown in Ohio, New Mexico and Colombia soils.

PubMed

Turgut, Cafer; Pepe, M Katie; Cutright, Teresa J

2005-02-01

The use of two EDTA concentrations for enhancing the bioavailability of cadmium, chromium, and nickel in three natural soils (Ohio, New Mexico and Colombia) was investigated. The resulting uptake, translocation and selectivity with Helianthus annuus after mobilization were also examined. In general, plants grown in the sandy-loam Ohio soil had a higher uptake that resulted in a selectivity and total metal content of Cd>Cr>Ni and 0.73 mg and Cr>Cd>Ni and 0.32 mg for 0.1 and 0.3 g kg-1 EDTA, respectively. With the silty-loam New Mexico soil, although the total metal uptake was not statistically different the EDTA level did alter the selectivity; Cd>Cr>Ni (0.1 g kg-1 EDTA) and Cd>Cr>Ni (0.3 g kg-1 EDTA). Conversely, with the Colombian (sandy clay loam) soil increasing the EDTA level resulted in a higher total metal uptake (0.62 mg) than the 0.1 g kg-1 (0.59 mg) treatment. For all three soils, the translocation of Cd was limited. Evaluating the mobile metal fraction with and without EDTA determined that the chelator was capable of overcoming mass transfer limitations associated with the expandable clay fraction in the soils. Root wash results and root biomass concentrations indicated that Cd sorption was occurring. Therefore limited Cd translocation was attributed to insufficient phytochelatin levels.

Creatine ingestion augments dietary carbohydrate mediated muscle glycogen supercompensation during the initial 24 h of recovery following prolonged exhaustive exercise in humans.

PubMed

Roberts, Paul A; Fox, John; Peirce, Nicholas; Jones, Simon W; Casey, Anna; Greenhaff, Paul L

2016-08-01

Muscle glycogen availability can limit endurance exercise performance. We previously demonstrated 5 days of creatine (Cr) and carbohydrate (CHO) ingestion augmented post-exercise muscle glycogen storage compared to CHO feeding alone in healthy volunteers. Here, we aimed to characterise the time-course of this Cr-induced response under more stringent and controlled experimental conditions and identify potential mechanisms underpinning this phenomenon. Fourteen healthy, male volunteers cycled to exhaustion at 70 % VO2peak. Muscle biopsies were obtained at rest immediately post-exercise and after 1, 3 and 6 days of recovery, during which Cr or placebo supplements (20 g day(-1)) were ingested along with a prescribed high CHO diet (37.5 kcal kg body mass(-1) day(-1), >80 % calories CHO). Oral-glucose tolerance tests (oral-GTT) were performed pre-exercise and after 1, 3 and 6 days of Cr and placebo supplementation. Exercise depleted muscle glycogen content to the same extent in both treatment groups. Creatine supplementation increased muscle total-Cr, free-Cr and phosphocreatine (PCr) content above placebo following 1, 3 and 6 days of supplementation (all P < 0.05). Creatine supplementation also increased muscle glycogen content noticeably above placebo after 1 day of supplementation (P < 0.05), which was sustained thereafter. This study confirmed dietary Cr augments post-exercise muscle glycogen super-compensation, and demonstrates this occurred during the initial 24 h of post-exercise recovery (when muscle total-Cr had increased by <10 %). This marked response ensued without apparent treatment differences in muscle insulin sensitivity (oral-GTT, muscle GLUT4 mRNA), osmotic stress (muscle c-fos and HSP72 mRNA) or muscle cell volume (muscle water content) responses, such that another mechanism must be causative.

Hexavalent chromium induced stress and metabolic responses in hybrid willows.

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong; Huang, Shen-Zhuo

2007-04-01

Metabolic responses to hexavalent chromium (Cr(6+)) stress and the uptake and translocation of Cr(6+ )were investigated using pre-rooted hybrid willows (Salix matsudana Koidz x Salix alba L.) exposed to hydroponic solution spiked with K(2)CrO(4) at 24.0 +/- 1 degrees C for 192 h. Various physiological parameters of the plants were monitored to determine toxicity from Cr(6+ )exposure. At Cr(6+) treatments of 50% higher than that of the non-treated control plants. As Cr concentrations were increased further, a slight increase in the transpiration rate was also observed compared with the controls. Negligible difference in the chlorophyll contents in leaves between the treated and the non-treated control plants was measured, except for willows exposed to 1.05 mg Cr/l. The response of soluble proteins in leaves of willows to Cr treatments was remarkable. Cr-induced toxicity appeared in all treatments resulting in reduced activities of catalase (CAT) and peroxidase (POD) compared to the controls. Superoxide dismutases (SOD) activity in the leaf cells showed a positive increase after Cr exposure. Of all selected parameters, soluble proteins in leaves were the most sensitive to Cr(6+ )doses, showing a significant linear correlation negatively (R (2) = 0.931). Uptake of Cr(6+) by willows grown in flasks was found to increase linearly with the added Cr(6+ )(a zero order kinetics), as indicated by the high R (2) (0.9322). Recovery of Cr in different parts of plant materials varied significantly with roots being the dominant site of Cr accumulation. Although the translocation to shoots was detected, the amount of Cr translocated to shoots was considerably small. The capacity of willows to assimilate Cr(6+ )was also evaluated using detached leaves and roots in sealed glass vessels in vivo. Uptake of Cr by roots was mediated possibly through an active transport mechanism, whereas the cuticle of leaves was the major obstacle to uptake Cr from the hydroponic solution. In addition, both cysteine and ascorbic acid showed a remarkable potential to reduce Cr(6+) at a neutral pH. Results indicated that the added Cr did not cause deleterious effects on plant physiological functions over a 192-h period of exposure. Significant removal of Cr from the hydroponic solution was observed in the presence of hybrid willows. The data also suggest that phytoremediation of Cr(6+) is possible and ecologically safe due to the minor translocation of Cr to aerial tissues.

Effects of drinking water quality on urinary parameters in men with and without urinary tract stones.

PubMed

Mirzazadeh, Majid; Nouran, Mina Ghadimi; Richards, Kyle A; Zare, Mariam

2012-03-01

There is some controversy regarding the impact of water hardness on stone risk. Our study addresses this issue in a controlled setting. Fifteen stone-former (SF) and 14 non-stone-former (NSF) males participated in this study in 3 intervals of 2 days each. Subjects collected a 24-hour urine sample while consuming a self-selected diet. They were then administered controlled diets. During the first 2 days, patients consumed water of minimal hardness (WMH), followed by tap water (TW) with moderate hardness on days 3 and 4, and mineral water (MW) on the final 2 days. Calcium (Ca), phosphorus, uric acid, oxalate, citrate, magnesium (Mg), sodium, potassium, and creatinine (Cr) content were measured in 24-hour urine samples on days 2, 4, and 6. Differences in water hardness and analytes were statistically significant among the different water types (P < .05). Urinary output in both groups increased during intervention with all 3 varieties of water (P < .05). Specific gravity of urine decreased in both groups drinking WMH and TW (P < .05) but not with MW. Mg/g Cr level was higher in NSF at baseline (P < .01), WMH (P < .05), and TW (P < .05). With the increase in drinking water hardness, Ca/g Cr ratio increased in SF but not in NSF (P < .05). NSF had significantly higher urinary Mg/g Cr excretion rate before intervention than SF (P < .01). Increasing drinking water hardness while controlling for all other factors increased Ca/g Cr ratio in SF, rendering them at least theoretically more inclined to stone formation. Copyright © 2012 Elsevier Inc. All rights reserved.

[Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang].

PubMed

Qi, Peng; Yu, Shu-quan; Zhang, Chao; Liang, Li-cheng; Che, Ji-lu

2015-12-01

In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang, we analyzed the concentrations of 10 heavy metals including Ti, Cr, Mn, Co, Ni, Cu, Zn, As, Pb and Fe in 122 sediment samples, explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geo-accumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn > Zn > Cr > Cu > Ph > Ni > As > Co, all heavy metals except for Ti were 1. 17 to 3.78 times higher than those of Zhejiang Jinhua- Quzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other, indicating that those heavy metals had similar sources of pollution, and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti, thereinto, Cr, Zn, Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti, Cu and As contributed the most to the total potential ecological risk, accounting for 22.84% and 21. 62% , others had a total of 55.54% , through the ecological risk assessment, 89. 34% of the potential ecological risk indexes ( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total, but was heavy in local areas.

Distribution, Fraction, and Ecological Assessment of Heavy Metals in Sediment-Plant System in Mangrove Forest, South China Sea.

PubMed

Li, Ruili; Chai, Minwei; Qiu, Guo Yu

2016-01-01

Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest.

Trace metals in sediments and benthic animals from aquaculture ponds near a mangrove wetland in Southern China.

PubMed

Wu, Hao; Liu, Jinling; Bi, Xiangyang; Lin, Guanghui; Feng, Christopher C; Li, Zhengjie; Qi, Fei; Zheng, Tianling; Xie, Liqi

2017-04-15

In this study, we measured the concentrations of trace metals (Cr, Cu, Zn, As, Cd, Pb and Hg) in typical cultured animals (crabs, clams, and shrimps) and sediments from aquaculture ponds nearby mangrove wetlands in Zhangjiang estuary, China. The contents of Cr, Cu, Cd, and Pb in mangrove sediments were significantly higher than those in pond sediments, while an inverse distribution was observed for Zn, As, and Hg. Significantly higher concentrations of trace metals were found in clams from the mangrove mudflats compared to those from the aquaculture ponds. The sources of trace metals in the clams were primarily from organic fertilizer, whereas those in the shrimp were from contaminated sediment. The results of geo-accumulation index and the ecological risk assessment indicated that the aquaculture ponds near the mangrove wetlands in this subtropical estuary posed a special risk of endogenous and exogenous trace metal pollution to nearby systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distribution, Fraction, and Ecological Assessment of Heavy Metals in Sediment-Plant System in Mangrove Forest, South China Sea

PubMed Central

Li, Ruili; Chai, Minwei; Qiu, Guo Yu

2016-01-01

Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest. PMID:26800267

Spatial distribution and potential biological risk of some metals in relation to granulometric content in core sediments from Chilika Lake, India.

PubMed

Barik, Saroja K; Muduli, Pradipta R; Mohanty, Bita; Rath, Prasanta; Samanta, Srikanta

2018-01-01

The article presents first systematic report on the concentration of selected major elements [iron (Fe) and manganese (Mn)] and minor elements [zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), and cobalt (Co)] from the core sediment of Chilika Lake, India. The analyzed samples revealed higher content of Pb than the background levels in the entire study area. The extent of contamination from minor and major elements is expressed by assessing (i) the metal enrichments in the sediment through the calculations of anthropogenic factor (AF), pollution load index (PLI), Enrichment factor (EF), and geoaccumulation index (Igeo) and (ii) potential biological risks by the use of sediment quality guidelines like effect range median (ERM) and effect range low (ERL) benchmarks. The estimated indices indicated that sediment is enriched with Pb, Ni, Cr, Cu and Co. The enrichment of these elements seems to be due to the fine granulometric characteristics of the sediment with Fe and Mn oxyhydroxides being the main metal carriers and fishing boats using low grade paints, fuel, and fishing technology using lead beads fixed to fishing nets. Trace element input to the Chilika lake needs to be monitored with due emphasis on Cr and Pb contaminations since the ERM and ERL benchmarks indicated potential biological risk with these metals.

Mantle Water Contents Beneath the Rio Grande Rift (NM, USA): FTIR Analysis of Rio Puerco and Kilbourne Hole Peridotite Xenoliths

NASA Technical Reports Server (NTRS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A.; Selverstone, J.

2015-01-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H (sub 2) O contents by FTIR (Fourier Transform Infrared) as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al)) (0.08-0.46) and olivine Mg# (Mg/(Mg plus Fe)) (0.883-0.911) of all RGR samples fall within the olivine-spinel mantle array from [1], an indicator that peridotites are residues of partial melting. Pyroxene H (sub 2) O in KH correlate with bulk rock and pyroxene Al (sub 2) O (sub 3).The KH clinopyroxene rare earth element (REE) variations fit models of 0-13 percent fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H (sub 2) O content is unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H (sub 2) O contents are low (less than or equal to 15 parts per million), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H (sub 2) O contents are still preserved in cores of KH olivine, but not RP olivine. The average H (sub 2) O content of Colorado Plateau clinopyroxene (670 parts per million) [4] is approximately 300 parts per million higher than RGR clinopyroxene (350 parts per million). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, approximately 600 kilometers from the paleo-trench, but less likely approximately 850 kilometers away beneath the rift [6].

Mobility and storage sinks for chromium and other metals in soils impacted by leather tannery wastes.

PubMed

Chen, Hualin; Arocena, Joselito M; Li, Jianbing; Thring, Ronald W; Zhou, Jiangmin

2012-12-01

Leather tanneries around the world, including China, introduce chromium (Cr) and other metals into the environment. In China, the population pressure compels the utilization of every piece of available land for food production. In this study, we investigated the content, leachability and possible storage sinks for Cr and other metals in soils around facilities of leather industry in southern China. It was found that Cr in soils impacted by tannery can be as high as 2484 mg Cr kg⁻¹ soil, and the mean contents of other metals such as Zn (214 mg Zn kg⁻¹ soil), Cd (5.4 mg Cd kg⁻¹ soil), As (17 mg As kg⁻¹ soil) exceeded the soil quality standards and guidelines in China and Canada. Simulated leaching studies (i.e., Synthetic Precipitation Leaching Procedure) indicated that these soils could release Cr and other metals in concentrations above the environmental quality guidelines and standards for water in China and Canada. As a result, the mobility of metals from these soils can potentially contaminate both groundwater and surface water. We also found differential leachability of metals with soil properties such as total metal and total carbon contents. Principal component analysis of the total contents of 32 elements showed that the possible major sinks for Cr are organic matter and oxides of Fe/Mn/Al, while sulfates and phosphates are potential storage of Cd, Zn, Cu and Pb. The information obtained from this study can be valuable for the restoration of ecosystem functions (i.e., food production) in the study area.

Magnetic and thermoelectric properties of the ternary pseudo-hollandite BaxCr5Se8 (0.5 < x < 0.55) solid solution.

PubMed

Lefèvre, Robin; Berthebaud, David; Bux, Sabah; Hébert, Sylvie; Gascoin, Franck

2016-07-26

The structure of Ba0.5Cr5Se8 has been recently resolved, and its thermoelectric and magnetic properties have been studied. A ZT of 0.12 was found at around 800 K. Here, we report a study on the pseudo-hollandite BaxCr5Se8 solid-solution with 0.5 ≤ x ≤ 0.55 and its thermoelectric and magnetic properties. There is no significant impact either on the cell parameters depending on the cation content or on the magnetic properties. However, thermoelectric properties are radically changed depending on x content. While the low thermal conductivity, around 0.8 W m(-1) K(-1), remains similar for all samples, a respective increase and decrease of the resistivity and the Seebeck coefficient are observed with increasing Ba content. The maximum Seebeck coefficient is found with Ba0.5Cr5Se8 at around 635 K with 315 μV K(-1), and the Seebeck coefficient then decreases and is correlated with an activation of minority charge carriers confirmed by Hall measurements. A similar but steeper behavior is observed for the Ba0.55Cr5Se8 temperature dependence plot at around 573 K. Finally, the best thermoelectric performances are found using the lowest content of Ba, unlike when x tends to 0.55, ZT approaches a tenth of the initial best value. BaxCr5Se8 compounds are antiferromagnetic with TN = 58 K. A large peak in thermal conductivity is observed around the antiferromagnetic transition for all stoichiometry.

Mantle water contents beneath the Rio Grande Rift (NM, USA): FTIR analysis of Rio Puerco and Kilbourne Hole peridotite xenoliths

NASA Astrophysics Data System (ADS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A. D.; Selverstone, J.

2015-12-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H2O contents by FTIR as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al) = 0.08-0.46) and olivine Mg# (Mg/(Mg+Fe) = 0.883-0.911) of samples fall within the olivine-spinel mantle array from [1], an indicator that these are residues of partial melting. Pyroxene H2O contents in KH correlate with bulk rock and pyroxene Al2O3 contents. The KH clinopyroxene rare earth element (REE) variations fit models of 0-13% fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H2O content seems unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H2O contents are low (≤20 ppm), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H2O contents are still preserved in cores of KH olivine, but not those of RP olivine. The average H2O content of Colorado Plateau clinopyroxene (670 ppm) [4] is ~300 ppm higher than RGR clinopyroxene (350 ppm). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, ~600 km from the paleo-trench, but less likely ~850 km away beneath the rift [6]. [1]Arai, 1994 CG 113, 191-204.[2]Porreca et al., 2006 Geosp 2, 333-351.[3]Peslier and Luhr, 2006 EPSL 242, 302-319.[4]Li et al., 2008 JGR 113, 1978-2012.[5]Humphreys et al., 2003 Int Geol Rev 45, 575-595.[6]English et al., 2003 EPSL 214, 619-632.

Trap depth and color variation of Ce3+-Cr3+ co-doped Gd3(Al,Ga)5O12 garnet persistent phosphors

NASA Astrophysics Data System (ADS)

Asami, Kazuki; Ueda, Jumpei; Tanabe, Setsuhisa

2016-12-01

Persistent luminescent properties in Ce3+-Cr3+ codoped Gd3Al5-xGaxO12 garnet (GAGG:Ce-Cr) solid solution have been investigated. The persistent luminescent color is shifted from orange to yellowish green with increasing Ga content because Ce3+: 5d level splitting becomes much weaker. The depth of electron trap introduced by Cr codoping was estimated from the intense thermoluminescence glow peak by the initial rise method. The trap depth decreases from 0.56 eV to 0.29 eV with increasing Ga content. The shift can be explained by downshift of bottom of conduction band. From the persistent luminescence decay curve measurement after ceasing 450 nm blue illumination, the samples with x = 2.5 exhibited the longest persistent luminescence for 405 min until the luminance becomes 2 mcd/m2 in GAGG:Ce-Cr phosphors.

A New Method to Produce Ni-Cr Ferroalloy Used for Stainless Steel Production

NASA Astrophysics Data System (ADS)

Chen, Pei-Xian; Chu, Shao-Jun; Zhang, Guo-Hua

2016-08-01

A new electrosilicothermic method has been proposed in the present paper to produce Ni-Cr ferroalloy, which can be used for the production of 300 series stainless steel. Based on this new process, the Ni-Si ferroalloy is first produced as the intermediate alloy, and then the desiliconization process of Ni-Si ferroalloy melt with chromium concentrate is carried out to generate Ni-Cr ferroalloy. The silicon content in the Ni-Si ferroalloy produced in the submerged arc furnace should be more than 15 mass% (for the propose of reducing dephosphorization), in order to make sure the phosphorus content in the subsequently produced Ni-Cr ferroalloy is less than 0.03 mass%. A high utilization ratio of Si and a high recovery ratio of Cr can be obtained after the desiliconization reaction between Ni-Si ferroalloy and chromium concentrate in the electric arc furnace (EAF)-shaking ladle (SL) process.

Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques

NASA Astrophysics Data System (ADS)

Liu, Min; Zheng, Junyi; Lu, Yanling; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai

2013-09-01

Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (μ-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from μ-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

Si-rich Fe-Ni grains in highly unequilibrated chondrites

NASA Technical Reports Server (NTRS)

Rambaldi, E. R.; Sears, D. W.; Wasson, J. T.

1980-01-01

Consideration is given to the Si contents of Fe-Ni grains in highly unequilibrated chondrites, which have undergone little metamorphosis and thus best preserve the record of processes in the solar nebula. Electron microprobe determinations of silicon content in grains of the Bishunpur chondrite are presented for the six Si-bearing Fe-Ni grains for which data could be obtained, five of which were found to be embedded in olivine chondrules. In addition, all grains are found to be Cr-rich, with Cr increased in concentration towards the grain edge, and to be encased in FeS shells which evidently preserved the Si that entered the FeNi at higher temperatures. A mechanism for the production of Si-bearing metal during the condensation of the cooling solar nebula is proposed which considers the metal to have condensed heterogeneously while the mafic silicates condensed homogeneously with amounts of required undercooling in the low-pressure regions where ordinary and carbonaceous chondrites formed, resulting in Si mole fractions of 0.003 at nebular pressures less than 0.000001 atm.

Characterization of corrosion phenomena and kinetics on T91 ferritic/martensitic steel exposed at 450 and 550 °C to flowing Pb-Bi eutectic with 10-7 mass% dissolved oxygen

NASA Astrophysics Data System (ADS)

Tsisar, Valentyn; Schroer, Carsten; Wedemeyer, Olaf; Skrypnik, Aleksandr; Konys, Jürgen

2017-10-01

Corrosion behavior of two heats of T91 ferritic/martensitic steel, with slightly different Cr content, was investigated in flowing (2 m/s) Pb-Bi with 10-7 mass%O at 450 and 550 °C. The observed corrosion modes are: protective scale formation; accelerated oxidation and solution-based corrosion attack. Accelerated oxidation at 450 °C results in general metal recession of about 10 μm after ∼9000 h exposure and ∼15 μm at 550 °C after 2000 h. More severe and local solution-based corrosion results in a maximum depth of attack of 50-960 μm and 115-190 μm, correspondingly. Incubation period for solution-based corrosion is 500-5000 h at 450 °C and ≤500 h at 550 °C. The slightly higher chromium content in one of the heat of T91 steel prolongs the incubation period by improving the stability of the Cr-based oxide film.

Remotely Delivered Exercise-Based Cardiac Rehabilitation: Design and Content Development of a Novel mHealth Platform.

PubMed

Rawstorn, Jonathan C; Gant, Nicholas; Meads, Andrew; Warren, Ian; Maddison, Ralph

2016-06-24

Participation in traditional center-based cardiac rehabilitation exercise programs (exCR) is limited by accessibility barriers. Mobile health (mHealth) technologies can overcome these barriers while preserving critical attributes of center-based exCR monitoring and coaching, but these opportunities have not yet been capitalized on. We aimed to design and develop an evidence- and theory-based mHealth platform for remote delivery of exCR to any geographical location. An iterative process was used to design and develop an evidence- and theory-based mHealth platform (REMOTE-CR) that provides real-time remote exercise monitoring and coaching, behavior change education, and social support. The REMOTE-CR platform comprises a commercially available smartphone and wearable sensor, custom smartphone and Web-based applications (apps), and a custom middleware. The platform allows exCR specialists to monitor patients' exercise and provide individualized coaching in real-time, from almost any location, and provide behavior change education and social support. Intervention content incorporates Social Cognitive Theory, Self-determination Theory, and a taxonomy of behavior change techniques. Exercise components are based on guidelines for clinical exercise prescription. The REMOTE-CR platform extends the capabilities of previous telehealth exCR platforms and narrows the gap between existing center- and home-based exCR services. REMOTE-CR can complement center-based exCR by providing an alternative option for patients whose needs are not being met. Remotely monitored exCR may be more cost-effective than establishing additional center-based programs. The effectiveness and acceptability of REMOTE-CR are now being evaluated in a noninferiority randomized controlled trial.

Matrix Transformation in Boron Containing High-Temperature Co-Re-Cr Alloys

NASA Astrophysics Data System (ADS)

Strunz, Pavel; Mukherji, Debashis; Beran, Přemysl; Gilles, Ralph; Karge, Lukas; Hofmann, Michael; Hoelzel, Markus; Rösler, Joachim; Farkas, Gergely

2018-03-01

An addition of boron largely increases the ductility in polycrystalline high-temperature Co-Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ɛ (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co-17Re-23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ɛ to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co-17Re-23Cr-1.2Ta-2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0-1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.

Assessment of different methods to estimate heavy metal bioavailability in 30 contrasting Spanish and New Zealand soils

NASA Astrophysics Data System (ADS)

Soriano-Disla, J. M.; Speir, T. W.; Gómez, I.; Clucas, L. M.; McLaren, R. G.; Navarro-Pedreño, J.

2009-04-01

The accumulation of heavy metals in soil from different sources (atmospheric deposition, agricultural practices, urban-industrial activities, etc.) is of a great environmental concern because of metal persistence and toxicity. In this sense, there is a consensus in the literature that the estimation of the bioavailable heavy metals in soil is a preferable tool to determine potential risks from soil contamination than the total contents. However, controversy exists around the definition of an accurate and universal bioavailability estimator that is useful for soils with different properties, since many factors control this parameter. Thus, the main objective of this work was to compare the effectiveness of different methods to predict heavy metals plant uptake from soils with different properties and heavy metal contents. For the development of the present work, 30 contrasting soils from New Zealand and Spain were selected. Apart from the analysis of the basic soil properties, different methods to estimate heavy metal bioavailability were performed: total heavy metals, DTPA-extractable soil metals, diffusive gradient technique (DGT), and total heavy metals in soil solution. In these soils, a bioassay using wheat (Triticum aestivum) was carried out in a constant environment room for 25 days (12 hours photoperiod, day and night temperature of 20°C and 15°C respectively). After this time, the plants were divided in roots and shoots and heavy metal content was analysed in each part. Simple correlations were performed comparing the phytoavailable contents with the bioavailability estimated by the different methods. As expected, higher heavy metal concentrations were found in roots compared with shoots. Comparing the theoretical available heavy metals estimated by the different methods with the root and shoot uptake, better correlations were found with the root contents, thus, the discussion is based in the comparisons with the uptake by this part of the plant. According to the results, DTPA seemed to be the extractant that best estimated plant uptake (except for Cd, not estimated by any of the methods used). Similar good results were found using the total heavy metal contents, except for Ni and Zn. DGT also worked well, but its use for Pb is not advisable, since many values were below the detection level. The heavy metals in soil solution were less successful for predicting plant uptake. In general, the good results obtained for Cr and Zn seemed to be influenced by a few high values found in some soils. Taking this point into account, the soils with very high levels of these heavy metals were removed from the analysis and simple correlations were done again with the remaining soils having a lower range of these metals. For the case of Cr, four soils were removed (soils with ten times or more total Cr than the average of the others 26 samples) and three for the case of Zn (soils with two times or more total Zn than the average of the others 27 samples). After this, the correlations with total heavy metals and DTPA became very weak, being the heavy metals in soil solution for Cr, and DGT for Zn, the methods that best estimated the plant uptake of these metals. This work has proved the importance of careful revision of the data distribution, since good results can be influenced by just few samples with high values. In this sense and as a conclusion, DTPA and total heavy metals followed similar patterns and were good predictors of Cu and Pb uptake, and useful to distinguish between low and high values for Cr and Zn. On the other hand, DGT and heavy metals in soil solution showed a similar effectiveness to estimate Cu, Ni, Pb, Zn and Cr, but DGT presented, in general, higher correlation levels (except for Cr). Taking all of the results together, it seems that the most robust and efficient estimator for all metals studied (except Cd, impossible to predict with any of the methods used) was the DGT. Acknowledgements: Jose. M. Soriano-Disla gratefully acknowledges the Spanish Ministry of Innovation and Culture for a research fellowship (AP2005-0320).

Effect of W and N on mechanical properties of reduced activation ferritic/martensitic EUROFER-based steel grades

NASA Astrophysics Data System (ADS)

Puype, A.; Malerba, L.; De Wispelaere, N.; Petrov, R.; Sietsma, J.

2018-04-01

The C, N, and W content in EUROFER97, a 9CrWVTa reduced-activation ferritic/martensitic (RAFM) steel, was varied to obtain an experimental assessment of the main effects of the compositional variation on the mechanical properties and microstructural characteristics of six different experimental grades. Light optical microscopy (LOM) and electron back-scattered diffraction (EBSD) revealed in almost all cases a fine tempered lath martensite structure. Analyses of transmission electron micrographs, together with inductively coupled plasma mass spectrometry (ICPMS) and energy-dispersive x-ray spectroscopy (EDS) data, shows the precipitation state and spatial distribution of MxCy (M = Cr, W and Fe) and MX (M = V and/or Ta, X = C or N) carbonitrides within the matrix. The mechanical characterization of the six different steel grades was carried out by means of A50 tensile testing and Charpy tests on standard specimens (55 × 10 × 10 mm3). Lowering the carbon content and keeping the nitrogen content higher than 0.02 wt%, leads to a reduction of the ductile-to-brittle-transition-temperature (DBTT) in comparison with EUROFER97-2. The addition of tungsten further reduces the DBTT to - 94 °C, while maintaining good tensile strength and elongation.

Chromium in soil layers and plants on closed landfill site after landfill leachate application.

PubMed

Zupancic, Marija; Justin, Maja Zupancic; Bukovec, Peter; Selih, Vid Simon

2009-06-01

Landfill leachate (LL) usually contains low concentrations of heavy metals due to the anaerobic conditions in the methanogenic landfill body after degradation of easily degradable organic matter and the neutral pH of LL, which prevents mobilization and leaching of metals. Low average concentrations of metals were also confirmed in our extensive study on the rehabilitation of an old landfill site with vegetative landfill cover and LL recirculation after its treatment in constructed wetland. The only exception was chromium (Cr). Its concentrations in LL ranged between 0.10 and 2.75 mg/L, and were higher than the concentrations usually found in the literature. The objectives of the study were: (1) to understand why Cr is high in LL and (2) to understand the fate and transport of Cr in soil and vegetation of landfill cover due to known Cr toxicity to plants. The total concentration of Cr in LL, total and exchangeable concentrations of Cr in landfill soil cover and Cr content in the plant material were extensively monitored from May 2004 to September 2006. By obtained data on Cr concentration in different landfill constituents, supported with the data on the amount of loaded leachate, amount of precipitation and potential evapotranspiration (ETP) during the performance of the research, a detailed picture of time distribution and co-dependency of Cr is provided in this research. A highly positive correlation was found between concentrations of Cr and dissolved organic carbon (r=0.875) in LL, which indicates the co-transport of Cr and dissolved organic carbon through the system. Monitoring results showed that the substrate used in the experiment did not contribute to Cr accumulation in the landfill soil cover, resulting in percolation of a high proportion of Cr back into the waste layers and its circulation in the system. No negative effects on plant growth appeared during the monitoring period. Due to low uptake of Cr by plants (0.10-0.15 mg/kg in leaves and 0.05-0.07 mg/kg in stems of Salix purpurea), the estimated Cr offtake from LL by plants represented only a small proportion of the LL Cr mass load during the observation period, resulting in no dispersion of Cr into the environment through leaf drop.

Mantle Xenoliths from Central and South Vietnam: Petrology and Geochemistry

NASA Astrophysics Data System (ADS)

Hauzenberger, Christoph; Konzett, Juergen; Nguyen, Hoang; Nguyen, Khoi

2014-05-01

Mantle xenoliths, spinel lherzolites and subordinate amounts of spinel harzburgites and pyroxenites, are commonly found in alkali basalts from south-central Vietnam. The basalts are part of widespread Neogene volcanism found in southern China and Indochina regions. Samples from different localities between the cities of Ban Me Thuot and Saigon were recovered. In addition one xenolith sample from an off-shore volcano SE of Ho Chi Minh City in the South China Sea was investigated. The mineral assemblage in most samples consists of the simple lherzolitic mineral assemblage Ol-Opx-Cpx-Sp. The Ol, Cpx and Opx crystals are equigranular while Sp occurs usually as smaller sized intersertal phase or as partly oriented inclusions in Cpx. Cpx II occurs in some samples as recrystallized "spongy rim" around Cpx I. Cpx I has a a very uniform composition between different samples with a typical XMg (=Mg/(Mg+Fe2+) of 0.92 to 0.98, a XNa (=Na/(Na+Ca) of 0.10 to 0.16, a Cr2O3 content of 0.6-0.9 wt. .% and Al2O3 values of c. 6 to 8 wt.%. Cpx II has a lower XNa and Al content as well as higher XMg and Cr content compared to Cpx I. Orthopyroxene typically has a XMg of c. 0.90 to 0.93. The XMg values for Ol differ slightly between different samples but are within 0.84 to 0.94. Spinel grains have a variable composition with XMg from 0.65 to 0.92 and XCr (Cr/Cr+Al+Fe3+) of 0.08 to 0.25. The use of the Cpx-Opx thermometer (BREY & KOEHLER, 1990) and the Al and Cr in Ol thermometer (DE HOOG et al., 2010) allowed to constrain the temperature with 800 to 1100 °C. Trace and rare earth element composition of Cpx was determined by LA-ICPMS. While most Cpx compositions are slightly depleted in LREE, typical for average depleted mantle compositions, some samples are strongly enriched in LREE indicating mantle metasomatic processes. The sample displaying the highest level of LREE enrichment in Cpx has the lowest calculated temperature (T = c. 800°C) and the highest Ni content in olivine (3000 ppm). The variation in LREE as well as LIL element concentration in Cpx from different xenoliths is evidence for the heterogeneous nature of the mantle beneath Indochina. Financial support from the Austrian Academy of Sciences and ASEA-Uninet is gratefully acknowledged. This is a contribution to IGCP557.

Dietary Chromium Picolinate Supplementation Affects Growth, Whole-Body Composition, and Gene Expression Related to Glucose Metabolism and Lipogenesis in Juvenile Blunt Snout Bream, Megalobrama amblycephala.

PubMed

Ren, Mingchun; Mokrani, Ahmed; Liang, Hualiang; Ji, Ke; Xie, Jun; Ge, Xianping; Liu, Bo

2018-01-18

An 11-week feeding trial was carried out to investigate the effects of supplemented chromium picolinate (Cr-Pic) on the growth, whole-body composition, and relative mRNA expression related to lipogenesis and glucose metabolism in juvenile blunt snout bream. Seven isonitrogenous and isoenergetic diets with graded Cr supplementation levels were fed to triplicate groups. The final weight (FW), feed conversion ratio (FCR), and specific growth rate (SGR) were improved with increasing dietary Cr supplementation levels up to 0.4 mg/kg, and thereafter showed relatively constant. However, 12.0 mg/kg dietary Cr supplementation decreased growth and feed utilization. Based on SGR and FCR, the optimal dietary Cr supplementation level for the juvenile was estimated to be 0.28 mg/kg. Significantly higher plasma insulin levels were found in juvenile fed diets with 0.4 and 0.8 mg/kg Cr supplementation compared to those fed diet sans supplemented Cr. Plasma glucose levels decreased with increasing dietary Cr supplementation, and the lowest value was remarked in the group added 3.2 mg/kg of Cr. Adding 0.4-0.8 mg/kg Cr enhanced insulin receptor substrate 1 (IRS-1), phosphoinositide-3-kinase (PI3K), and pyruvate kinase (PK) and inhibited expression of phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), and glycogen synthase (GS) mRNA levels. High dietary Cr (12.0 mg/kg) supplementation resulted in high G6Pase and PEPCK expression. The highest content of whole-body lipid was remarked in fish fed with 0.4 mg/kg dietary Cr, which related to the enhanced gene expression related to lipogenesis; thereafter, mRNA levels showed a diminishing trend. These findings indicate that optimum dietary Cr-Pic supplementation has a positive effect on growth and blood glucose homeostasis by modifying the mRNA levels related to glucose metabolism and lipogenesis in juvenile blunt snout bream.

[Investigation and analysis of heavy metal pollution related to soil-Panax notoginseng system].

PubMed

Chen, Lu; Mi, Yan-Hua; Lin, Xin; Liu, Da-Hui; Zeng, Min; Chen, Xiao-Yan

2014-07-01

In this study, five heavy metals contamination of soil and different parts of Panax notoginseng in the plantation area was investigated. Analysis of heavy metals correlation between the planting soil and P. notoginseng; and the absorption and accumulation characteristics and translocation of soil heavy metals by P. notoginseng plants was revealed. Through field investigation and laboratory analytical methods, analysis of China's 30 different soil P. notoginseng origin and content of heavy metals in five different parts of the P. notoginseng plant content of heavy metals. The results revealed that the soil heavy metals should not be neglected in the plantation area Referring to the national soil quality standards (GB15608-1995), the excessive degree of soil heavy metals pollution showed Hg > As > Cd > Cr in the plantation area, and Pb content of soil was in the scope of the standard. Refer to 'Green Industry Standards for Import and Export of Medical Plants and Preparations', the excessive degree of heavy metals content of P. notoginseng plants showed As > Pb > Cr > Cd, and Hg content of plants was in the scope of the standard. Concentrations of five heavy metals of underground parts of P. notoginseng plants are higher than aboveground, and heavy metals elements are more concentrated in the root, followed by the rhizome of P. notoginseng plants. Heavy metal accumulation characteristics of the different parts of the P. notoginseng of the overall performance is the root > the rhizome > the root tuber > leaves > stems. From the point of view BCF value analysis of various parts of the P. notoginseng plants to absorb heavy metals in soil, BCF values of all samples were less than 1, description P. notoginseng not belong Hyperaccumulator. From the view of transportation and related analysis of the soil-P. notoginseng systems, the rhizome of P. notoginseng and the content of As and Cr in soil was significantly correlated, the root of P. notoginseng and the content of Cd in soil was significantly correlated, and no significant correlation between the other indicators. Through the analysis of transportation transfer coefficient showed: Pb, As and Cr are not easy to transport aboveground part from the underground, but Cd and Hg are relatively easy to transport stems from rhizome, the migration of five heavy metals in the aerial part is relatively strong, and heavy metal of stems is easily transported to the leaves. P. notoginseng does not belong to the enrichment of heavy metals in crops, especially for Hg in soil with strong patience. In survey area, the content of heavy metals of P. notoginseng's planting soil is relatively high, and the heavy metals As, Pb, Cr, Cd of P. notoginseng also exist heavy metals exceeded problems. Due to the presence of heavy metals in crops internal absorption and translocation of special laws, accumulation of heavy metals varied significantly in different parts of P. notoginseng. The overall, the performance for the heavy metal content of the underground parts is more than aboveground, it explain heavy metals of P. notoginseng plants is still the main source of the soiL Therefore, the key to control of planting area soil environmental quality and reduce exogenous harmful substances secondary pollution of soil in the cultivation process are to study and solve the heavy metals pollution problem of P. notoginseng.

High-Temperature Erosive Behavior of Plasma Sprayed Cr3C2-NiCr/Cenosphere Coating

NASA Astrophysics Data System (ADS)

Mathapati, Mahantayya; Doddamani, Mrityunjay; Ramesh, M. R.

2018-02-01

This research examines the deposition of Cr3C2-NiCr/cenosphere and Cr3C2-NiCr coatings on MDN 321 steel through the process of plasma spray. In this process, the solid particle erosion test is established at 200, 400, 600 °C with 30° and 90° impact angles. Alumina erodent is adopted to investigate the erosive behavior of the coating at higher temperatures. The properties of the Cr3C2-NiCr/cenosphere coating are established based on the microhardness, the adhesive strength, the fracture toughness, and the ductility. To quantify volume loss as a result of erosion, an optical profilometer is used. At higher temperature, decrease in the erosion volume loss of Cr3C2-NiCr/cenosphere and Cr3C2-NiCr coatings is observed. The erosion-resistive property of Cr3C2-NiCr/cenosphere coating is higher than that of MDN 321 steel by 76%. This property is influenced by high-temperature stability of mullite, alumina, and protective oxide layer that is formed at elevated temperatures. The morphology of eroded coating discloses a brittle mode of material removal.

Urinary ATP May Be a Dynamic Biomarker of Detrusor Overactivity in Women with Overactive Bladder Syndrome

PubMed Central

Oliveira, Olga; Ferreira, Sónia; Reis, Maria Júlia; Oliveira, José Carlos; Correia-de-Sá, Paulo

2013-01-01

Background Nowadays, there is a considerable bulk of evidence showing that ATP has a prominent role in the regulation of human urinary bladder function and in the pathophysiology of detrusor overactivity. ATP mediates nonadrenergic-noncholinergic detrusor contractions in overactive bladders. In vitro studies have demonstrated that uroepithelial cells and cholinergic nerves from overactive human bladder samples (OAB) release more ATP than controls. Here, we compared the urinary ATP concentration in samples collected non-invasively from OAB women with detrusor overactivity and age-matched controls. Methods Patients with neurologic diseases, history of malignancy, urinary tract infections or renal impairment (creatinine clearance <70 ml/min) were excluded. All patients completed a 3-day voiding diary, a 24 h urine collection and blood sampling to evaluate creatinine clearance. Urine samples collected during voluntary voids were immediately freeze-preserved for ATP determination by the luciferin-luciferase bioluminescence assay; for comparison purposes, samples were also tested for urinary nerve growth factor (NGF) by ELISA. Results The urinary content of ATP, but not of NGF, normalized to patients’ urine creatinine levels (ATP/Cr) or urinary volume (ATP.Vol) were significantly (P<0.05) higher in OAB women with detrusor overactivity (n = 34) than in healthy controls (n = 30). Significant differences between the two groups were still observed by boosting urinary ATP/Cr content after water intake, but these were not detected for NGF/Cr. In OAB patients, urinary ATP/Cr levels correlated inversely with mean voided volumes determined in a 3-day voiding diary. Conclusion A high area under the receiver operator characteristics (ROC) curve (0.741; 95% CI 0.62–0.86; P<0.001) is consistent with urinary ATP/Cr being a highly sensitive dynamic biomarker for assessing detrusor overactivity in women with OAB syndrome. PMID:23741373

Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhang, Jianli

2017-02-01

The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N2 in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr2N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitro`gen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T1). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N2-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential corrosion. The Cr2N precipitation led to relatively poor resistance to pitting corrosion in three HAZs and pure Ar shielding GTAW weld root. The N2-supplemented shielding gas improved pitting corrosion resistance of GTAW joint by increasing PREN of secondary austenite and suppressing Cr2N precipitation. In addition, the FCAW WM had much poorer resistance to pitting corrosion than the GTAW WM due to many O-Ti-Si-Mn inclusions. In the BM, since the austenite with lower PREN compared to the ferrite, the pitting corrosion occurred at the ferrite and austenite interface or within the austenite.

Chemical composition and some trace element contents in coals and coal ash from Tamnava-Zapadno Polje Coal Field, Serbia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vukasinovic-Pesic, V.; Rajakovic, L.J.

2009-07-01

The chemical compositions and trace element contents (Zn, Cu, Co, Cr, Ni, Pb, Cd, As, B, Hg, Sr, Se, Be, Ba, Mn, Th, V, U) in coal and coal ash samples from Tamnava-Zapadno Polje coal field in Serbia were studied. The coal from this field belongs to lignite. This high volatility coal has high moisture and low S contents, moderate ash yield, and high calorific value. The coal ash is abundant in alumosilicates. Many trace elements such as Ni > Cd > Cr > B > As > Cu > Co > Pb > V > Zn > Mn inmore » the coal and Ni > Cr > As > B > Cu > Co = Pb > V > Zn > Mn in the coal ash are enriched in comparison with Clarke concentrations.« less

A regional soil and sediment geochemical study in northern California

USGS Publications Warehouse

Goldhaber, M.B.; Morrison, J.M.; Holloway, J.M.; Wanty, R.B.; Helsel, D.R.; Smith, D.B.

2009-01-01

Regional-scale variations in soil geochemistry were investigated in a 20,000-km2 study area in northern California that includes the western slope of the Sierra Nevada, the southern Sacramento Valley and the northern Coast Ranges. Over 1300 archival soil samples collected from the late 1970s to 1980 in El Dorado, Placer, Sutter, Sacramento, Yolo and Solano counties were analyzed for 42 elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry following a near-total dissolution. These data were supplemented by analysis of more than 500 stream-sediment samples from higher elevations in the Sierra Nevada from the same study site. The relatively high-density data (1 sample per 15 km2 for much of the study area) allows the delineation of regional geochemical patterns and the identification of processes that produced these patterns. The geochemical results segregate broadly into distinct element groupings whose distribution reflects the interplay of geologic, hydrologic, geomorphic and anthropogenic factors. One such group includes elements associated with mafic and ultramafic rocks including Cr, Ni, V, Co, Cu and Mg. Using Cr as an example, elevated concentrations occur in soils overlying ultramafic rocks in the foothills of the Sierra Nevada (median Cr = 160 mg/kg) as well as in the northern Coast Ranges. Low concentrations of these elements occur in soils located further upslope in the Sierra Nevada overlying Tertiary volcanic, metasedimentary and plutonic rocks (granodiorite and diorite). Eastern Sacramento Valley soil samples, defined as those located east of the Sacramento River, are lower in Cr (median Cr = 84 mg/kg), and are systematically lower in this suite compared to soils from the west side of the Sacramento Valley (median Cr = 130 mg/kg). A second group of elements showing a coherent pattern, including Ca, K, Sr and REE, is derived from relatively silicic rocks types. This group occurs at elevated concentrations in soils overlying volcanic and plutonic rocks at higher elevations in the Sierras (e.g. median La = 28 mg/kg) and the east side of the Sacramento Valley (median 20 mg/kg) compared to soils overlying ultramafic rocks in the Sierra Nevada foothills (median 15 mg/kg) and the western Sacramento Valley (median 14 mg/kg). The segregation of soil geochemistry into distinctive groupings across the Sacramento River arises from the former presence of a natural levee (now replaced by an artificial one) along the banks of the river. This levee has been a barrier to sediment transport. Sediment transport to the Valley by glacial outwash from higher elevations in the Sierra Nevada and, more recently, debris from placer Au mining has dominated sediment transport to the eastern Valley. High content of mafic elements (and low content of silicic elements) in surface soil in the west side of the valley is due to a combination of lack of silicic source rocks, transport of ultramafic rock material from the Coast Ranges, and input of sediment from the late Mesozoic Great Valley Group, which is itself enriched in mafic elements. A third group of elements (Zn, Cd, As and Cu) reflect the impact of mining activity. Soil with elevated content of these elements occurs along the Sacramento River in both levee and adjacent flood basin settings. It is interpreted that transport of sediment down the Sacramento River from massive sulfide mines in the Klamath Mountains to the north has caused this pattern. The Pb, and to some extent Zn, distribution patterns are strongly impacted by anthropogenic inputs. Elevated Pb content is localized in major cites and along major highways due to inputs from leaded gasoline. Zinc has a similar distribution pattern but the source is tire wear.

Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

NASA Astrophysics Data System (ADS)

Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

2017-02-01

High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

Dissolution Mechanism for High Melting Point Transition Elements in Aluminum Melt

NASA Astrophysics Data System (ADS)

Lee, Young E.; Houser, Stephen L.

When added cold in aluminum melt, the alloying process for compacts of transition metal elements such as Mn, Fe, Cr, Ni, Ti, Cu, and Zn takes a sequence of incubation, exothermic reactions to form intermetallic compounds, and dispersion of the alloying elements into aluminum melt. The experiments with Cr compacts show that the incubation period is affected by the content of ingredient Al and size of compacts and by size of Cr particles. Incubation period becomes longer as the content of ingredient aluminum in compact decreases, and this prolonged incubation period negatively impacts the dissolution of the alloying elements in aluminum. Once liquid aluminum forms at reaction sites, the exothermic reaction takes place quickly and significantly raises the temperature of the compacts. As the result of it, the compacts swell in volume with a sponge like structure. Such porous structure encourages the penetration of liquid aluminum from the melt. The compacts become weak mechanically, and the alloying elements are dispersed and entrained in aluminum melt as discrete and small sized units. When Cr compacts are deficient in aluminum, the unreacted Cr particles are encased by the intermetallic compounds in the dispersed particles. They are carried in the melt flow and continue the dissolution reaction in aluminum. The entire dissolution process of Cr compacts completes within 10 to 15 minutes with a full recovery when the aluminum content is 10 to 20% in compacts.

Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

NASA Astrophysics Data System (ADS)

Guo, Jun; Huang, Xuefei; Huang, Weigang

2017-07-01

FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

Introduction to AIRS and CrIS

NASA Technical Reports Server (NTRS)

Susskind, Joel

2004-01-01

"Introduction to AIRS and CrIS" is a chapter in a book dealing with various aspects of remote sensing. AIRS and CrIS are both high spectral resolution IR sounding instruments, which were recently launched (AIRS) or will soon be launched (CrIS). The chapter explains the general principles of infra-red remote sensing, and explains the significance and information content of high spectral resolution IR measurements. The chapter shows results obtained using AIRS observations, and explains why similar quality results should be obtainable from CrIS data.

Physicochemical and sensory characteristics of fat-free goat milk yogurt with added stabilizers and skim milk powder fortification.

PubMed

Bruzantin, F P; Daniel, J L P; da Silva, P P M; Spoto, M H F

2016-05-01

Goat milk yogurt has a less consistent coagulum compared with cow milk yogurt; furthermore, the presence of goat milk in foodstuffs imparts a characteristic flavor that can restrict its acceptance by consumers. This study aimed to assess and compare the physicochemical and sensory characteristics of fat-free goat milk yogurts with added stabilizers or bovine skim milk powder to improve the final product. Four treatment additions were evaluated: (1) a mixture of 0.1% (wt/vol) carrageenan and 0.1% (wt/vol) pectin (treatment CR); (2) 0.5% (wt/vol) pectin (treatment PE); (3) 4.65% (wt/vol) bovine skim milk powder (treatment BM); and (4) control (no stabilizer; treatment CT). The physicochemical parameters were investigated at on d 1 and 5 of storage. The BM treatment presented higher pH and titratable acidity values, resulting in a buffering capacity effect. The total crude protein (CP) and solids-not-fat (SNF) contents were also higher in BM compared with the other evaluated treatments because of the addition of bovine skim milk powder. We detected a reduction in pH values for all treatments. Lower SNF contents were present in the CR and CT treatments, which might be related to a syneresis process during storage; moreover, an increase in total CP was observed for all treatments due to the proteolytic action of the starter culture. Sensory attributes, including appearance (color, consistency, and presence of lumps), texture (consistency, viscosity, and presence of lumps), flavor (bitter, sweet, and characteristic of commercial plain nonfat yogurt), and overall impression were evaluated by quantitative descriptive analysis. The addition of 0.5% (wt/vol) of pectin (PE treatment) strengthened the curd; however, the visual and oral presence of lumps and a higher bitterness score were noted by trained panelists, which resulted in the lowest overall impression score for the PE treatment. In several sensory attributes, the CR treatment was considered similar to the control; the mixture of 0.1% (wt/vol) carrageenan and 0.1% (wt/vol) pectin was not as effective as expected. Goat milk yogurt containing added bovine skim milk powder (BM) had improved consistency, viscosity, and flavor due to its higher SNF and total CP contents, which are particularly important for the desirable texture of plain nonfat yogurt. In addition, the BM yogurt was considered to have characteristics most similar to that of available commercial brands and achieved the best score for overall impression. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Do Dietary Habits Influence Trace Elements Release from Fixed Orthodontic Appliances?

PubMed

Wołowiec, Paulina; Chojnacka, Katarzyna; Loster, Bartłomiej W; Mikulewicz, Marcin

2017-12-01

The objective was to investigate the effect of dietary habits on the release of Cr and Ni ions from orthodontic appliances by hair mineral analysis. Patients (N = 47) underwent electronic questionnaire survey to investigate the effect of dietary habits on Cr and Ni levels in hair. The research was carried out on hair sampled at the beginning and in the 4th, 8th, and 12th months of the treatment. The content of Cr and Ni in the collected samples was determined by ICP-OES. The study showed that consumption of acidic dietary products may have the effect on increasing the release of Cr and Ni ions from orthodontic appliances. The release of Cr from orthodontic appliances in patients who consumed fruit juice, coffee, yoghurt, and vinegar was higher. The coefficients enabling comparison of metal ions release pattern at a given sampling points were defined. The comparison of the coefficients yielded the information on the possible magnification of metal ions released as the result of the additional factor consumption of acidic food or drink that intensifies metal ions release. The following magnification pattern was found for chromium: coffee (7.57 times) > yoghurt (2.53) > juice (1.86) > vinegar (1.08), and for nickel: vinegar (2.2) > coffee (1.22) > juice (1.05). Yoghurt did not intensify the release of nickel. Concluding, orthodontic patients should avoid drinking/eating coffee, yoghurt, fruit juices, and vinegar.

Development, pilot testing and psychometric validation of a short version of the coronary artery disease education questionnaire: The CADE-Q SV.

PubMed

Ghisi, Gabriela Lima de Melo; Sandison, Nicole; Oh, Paul

2016-03-01

To develop, pilot test and psychometrically validate a shorter version of the coronary artery disease education questionnaire (CADE-Q), called CADE-Q SV. Based on previous versions of the CADE-Q, cardiac rehabilitation (CR) experts developed 20 items divided into 5 knowledge domains to comprise the first version of the CADE-Q SV. To establish content validity, they were reviewed by an expert panel (N=12). Refined items were pilot-tested in 20 patients, in which clarity was provided. A final version was generated and psychometrically-tested in 132CR patients. Test-retest reliability was assessed via the intraclass correlation coefficient (ICC), the internal consistency using Cronbach's alpha, and criterion validity with regard to patients' education and duration in CR. All ICC coefficients meet the minimum recommended standard. All domains were considered internally consistent (α>0.7). Criterion validity was supported by significant differences in mean scores by educational level (p<0.01) and duration in CR (p<0.05). Knowledge about exercise and nutrition was higher than knowledge about medical condition. The CADE-Q SV was demonstrated to have good reliability and validity. This is a short, quick and appropriate tool for application in clinical and research settings, assessing patients' knowledge during CR and as part of education programming. Copyright © 2015. Published by Elsevier Ireland Ltd.

Synthesis and characterization of AlTiSiN/CrSiN multilayer coatings by cathodic arc ion-plating

NASA Astrophysics Data System (ADS)

Yang, B.; Tian, C. X.; Wan, Q.; Yan, S. J.; Liu, H. D.; Wang, R. Y.; Li, Z. G.; Chen, Y. M.; Fu, D. J.

2014-09-01

AlTiSiN/CrSiN multilayer coatings were deposited on Si (1 0 0) and cemented carbide substrates using Cr, AlTi cathodes and SiH4 gases by cathodic arc ion plating system. The influences of SiH4 gases flowrate on the structural and mechanical properties of the coatings were investigated, systematically. AlTiSiN/CrSiN coatings exhibit a B1 NaCl-type nano-multilayered structure in which the CrSiN nano-layers alternate with AlTiSiN nano-layers with multiple orientations of crystal planes indicated by XRD patterns and TEM. Si contents of the coatings increase with increasing SiH4 flowrate. The hardness of the coatings increases to the maximum value of 3500 Hv0.05 with increasing SiH4 flowrate from 20 to 40 sccm and then decreases with further addition of SiH4 gases. A higher adhesive force of 73 N is obtained at the flowrate of 48 sccm. The coatings exhibit different tribological performance when the mating materials were varied from Si3N4 to cemented carbide balls and the variation of friction coefficients of the coatings against Si3N4 influenced by SiH4 flowrate are not obvious as against cemented carbide balls.

Distribution of major and trace elements in surface sediments of the western Gulf of Thailand: Implications to modern sedimentation

NASA Astrophysics Data System (ADS)

Liu, Shengfa; Shi, Xuefa; Yang, Gang; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2016-04-01

In this study, we analyze major and trace elements (SiO2, Al2O3, Fe2O3, CaO, K2O, MgO, Na2O, TiO2, P2O5, MnO, Cu, Pb, Ba, Sr, V, Zn, Co, Ni, Cr, and Zr) and grain size of 157 surface sediment samples from the western Gulf of Thailand (GoT). On the basis of the space distribution characteristics, the study area can be classified into three geochemical provinces. Province I covers the northern and northwestern coastal zones of the GoT, including the whole upper GoT and thus the sediments from the rivers in the area. It contains high contents of SiO2. Province II is located in the middle of the GoT and has similar geochemistry composition as the South China Sea (SCS). It contains sediments that are characterized by higher contents of Na2O, TiO2, Ba, Cr, V, Zn, Zr, and Ni. Province Ш is located in the lower GoT, close to Malaysia. Major and trace elements in this area showed complex distribution patterns, which may be due to terrestrial materials from Malay rivers combining with some sediments from the SCS in this province. The results also indicate that grain size is the controlling factor in elemental contents, and that the hydrodynamic environment and mineral composition of the sediments play an important role in the distribution of these elements. The anthropogenic impact of heavy metal introduction (especially Cr, Zn, Cu, and Pb) can be seen in surface sediments from the nearshore region of Chantaburi province and north of Samui Island.

[Characteristics and Risk Assessment of Heavy Metals in Core Sediments from Lakes of Tibet].

PubMed

Guo, Bi-xi; Liu, Yong-qin; Zhang, Fan; Hou, Ju-zhi; Zhang, Hong-bo

2016-02-15

To explore the source of heavy metals in lake sediments and their hazard to environment on Tibetan Plateau, China, heavy metal (Cu, Zn, Cd, Pb, Cr, Co, Ni and As) levels in surface sediments of 18 lakes were investigated. Inductively Coupled Plasma Mass Spectrometry (ICP-MS, X-7 series) was used to determine the contents of heavy metals and the concentrations of carbon and nitrogen in sediment samples were analyzed by element analyzer (Vario Max CN, Elementar, Germany). The average concentrations for Cu, Zn, Cd, Pb, Cr, Co, Ni and As were 24.61 mg x kg(-1), 70.14 mg x kg(-1), 0.26 mg x kg(-1), 25.43 mg x kg(-1), 74.12 mg x kg(-1), 7.93 mg x kg(-1), 33.85 mg x kg(-1), 77.69 mg x kg(-1). It was found that heavy-metal concentrations in Tibet sediments were higher than those in Antarctic, but lower than those in the regions affected by anthropogenic activities. The contents of Cu, Zn, Pb, Cr and Co in the samples were lower than the background values of Tibet. Correlation analysis and principal components analysis (PCA) were used to analyze the origins of heavy metals. The result showed that Cu, Zn, Cd, Pb, Co, Ni and As came from soil in drainage basin and atmospheric deposition. Cr was mainly affected by human activities. Assessment on ecological risk of heavy metals was carried out using Hakanson's method and cluster analysis (CA). Assessment on ecological risk indicated that Pumoyum Co, Longmo Co and Bangong Co were at low risks, Bieruoze Co was at high ecological risk level and the other lakes were at different risk levels.

Influence of moisture content and temperature on degree of carbonation and the effect on Cu and Cr leaching from incineration bottom ash.

PubMed

Lin, Wenlin Yvonne; Heng, Kim Soon; Sun, Xiaolong; Wang, Jing-Yuan

2015-09-01

This study investigated the influence of moisture content and temperature on the degree of carbonation of municipal solid waste (MSW) incineration bottom ash (IBA) from two different incineration plants in Singapore. The initial rate of carbonation was affected by the nominal moisture content used. Carbonation temperature seemed to play a part in changing the actual moisture content of IBA during carbonation, which in turn affected the degree of carbonation. Results showed that 2h of carbonation was sufficient for the samples to reach a relatively high degree of carbonation that was close to the degree of carbonation observed after 1week of carbonation. Both Cu and Cr leaching also showed significant reduction after only 2h of carbonation. Therefore, the optimum moisture content and temperature were selected based on 2h of carbonation. The optimum moisture content was 15% for both incineration plants while the optimum temperature was different for the two incineration plants, at 35°C and 50°C. The effect on Cu and Cr leaching from IBA after accelerated carbonation was evaluated as a function of carbonation time. Correlation coefficient, Pearson's R, was used to determine the dominant leaching mechanism. The reduction in Cu leaching was found to be contributed by both formation of carbonate mineral and reduction of DOC leaching. On the other hand, Cr leaching seemed to be dominantly controlled by pH. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of alloy composition on cyclic flame hot-corrosion attack of cast nickel-base superalloys at 900 deg C

NASA Technical Reports Server (NTRS)

Deadmore, D. L.

1984-01-01

The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of nickel base alloys were investigated. The alloys were tested in a Mach 0.3 flame with 0.5 ppmw sodium at a temperature of 900 C. One nondestructive and three destructive tests were conducted. The best corrosion resistance was achieved when the Cr content was 12 wt %. However, some lower-Cr-content alloys ( 10 wt%) exhibited reasonable resistance provided that the Al content alloys ( 10 wt %) exhibited reasonable resistance provided that the Al content was 2.5 wt % and the Ti content was Aa wt %. The effect of W, Ta, Mo, and Nb contents on the hot-corrosion resistance varied depending on the Al and Ti contents. Several commercial alloy compositions were also tested and the corrosion attack was measured. Predicted attack was calculated for these alloys from derived regression equations and was in reasonable agreement with that experimentally measured. The regression equations were derived from measurements made on alloys in a one-quarter replicate of a 2(7) statistical design alloy composition experiment. These regression equations represent a simple linear model and are only a very preliminary analysis of the data needed to provide insights into the experimental method.

Magnetic cluster expansion model for random and ordered magnetic face-centered cubic Fe-Ni-Cr alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lavrentiev, M. Yu., E-mail: Mikhail.Lavrentiev@ukaea.uk; Nguyen-Manh, D.; Dudarev, S. L.

A Magnetic Cluster Expansion model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed, using DFT data spanning binary and ternary alloy configurations. Using this Magnetic Cluster Expansion model Hamiltonian, we perform Monte Carlo simulations and explore magnetic structures of alloys over the entire range of compositions, considering both random and ordered alloy structures. In random alloys, the removal of magnetic collinearity constraint reduces the total magnetic moment but does not affect the predicted range of compositions where the alloys adopt low-temperature ferromagnetic configurations. During alloying of ordered fcc Fe-Ni compounds with Cr, chromium atoms tend to replace nickel rathermore » than iron atoms. Replacement of Ni by Cr in ordered alloys with high iron content increases the Curie temperature of the alloys. This can be explained by strong antiferromagnetic Fe-Cr coupling, similar to that found in bcc Fe-Cr solutions, where the Curie temperature increase, predicted by simulations as a function of Cr concentration, is confirmed by experimental observations. In random alloys, both magnetization and the Curie temperature decrease abruptly with increasing chromium content, in agreement with experiment.« less

Exposure to Hexavalent Chromium Resulted in Significantly Higher Tissue Chromium Burden Compared With Trivalent Chromium Following Similar Oral Doses to Male F344/N Rats and Female B6C3F1 Mice

PubMed Central

Collins, Bradley J.; Stout, Matthew D.; Levine, Keith E.; Kissling, Grace E.; Fennell, Timothy R.; Walden, Ramsey; Abdo, Kamal; Pritchard, John B.; Fernando, Reshan A.; Burka, Leo T.; Hooth, Michelle J.

2010-01-01

In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight3/4 (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI). PMID:20843897

Exposure to hexavalent chromium resulted in significantly higher tissue chromium burden compared with trivalent chromium following similar oral doses to male F344/N rats and female B6C3F1 mice.

PubMed

Collins, Bradley J; Stout, Matthew D; Levine, Keith E; Kissling, Grace E; Melnick, Ronald L; Fennell, Timothy R; Walden, Ramsey; Abdo, Kamal; Pritchard, John B; Fernando, Reshan A; Burka, Leo T; Hooth, Michelle J

2010-12-01

In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight(3/4) (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI).

Urinary levels of nickel and chromium associated with dental restoration by nickel–chromium based alloys

PubMed Central

Chen, Bo; Xia, Gang; Cao, Xin-Ming; Wang, Jue; Xu, Bi-Yao; Huang, Pu; Chen, Yue; Jiang, Qing-Wu

2013-01-01

This paper aims to investigate if the dental restoration of nickel–chromium based alloy (Ni–Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni–Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of <1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of <1, 1 to <3 and 3 to <6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni–Cr alloy restoration need to be investigated. PMID:23579466

The Wenquan ultramafic rocks in the Central East Kunlun Fault zone, Qinghai-Tibet Plateau—crustal relics of the Paleo-Tethys ocean

NASA Astrophysics Data System (ADS)

Jia, Lihui; Meng, Fancong; Feng, Huibin

2018-06-01

The Wenquan ultramafic rocks, located in the East Kunlun Orogenic belt in the northeastern part of the Qinghai-Tibet Plateau, consist of dunite, wehrlite, olivine-clinopyroxenite and clinopyroxenite, and exhibit cumulate textures. Olivine from dunite has high Fo (forsterite, 90.0-91.8 wt%) and NiO content (0.15-0.42 wt%). Cr-spinels from all of the rocks in this suite are characterized by high Cr# (100×[Cr/(Cr + Al)], 67-91), low Mg# (100×[Mg/(Mg + Fe2+)], 17-35) and low TiO2 contents (mostly < 0.5 wt%). Clinopyroxene displays high Mg# (92-98) and low TiO2 content (0.002-0.099 wt%), similar to those in ophiolitic cumulates. Geochemically, the Wenquan ultramafic rocks show enrichment of LILE, Sr, and Ba, and depletion of Nb and Th. High-Mg# (mostly > 80) and low-CaO (< 0.08 wt%) olivine, high-Cr# (up to 91) spinel, and low Ti contents of clinopyroxene and Cr-spinel indicate that the Wenquan cumulates were generated by high-degree partial melting of a depleted oceanic lithosphere mantle. The ultramafic intrusion most likely evolved from high-Mg basaltic magmas (Mg# = 77.5) that underwent fractional crystallization and crustal contamination. Zircon grains from clinopyroxenites yield a U-Pb weighted mean age of 331 ± 2 Ma, which is nearly coeval with the formation age of the A'nyemaqen ophiolites. The Wenquan Carboniferous ophiolites are confirmed to exist in the Central East Kunlun Fault zone, whereas previous studies have considered them to be the Proterozoic ophiolites. The Wenquan ophiolite might be a relict of the Paleotethyan ocean, indicating that there were two cycles of oceanic-continental evolution along the Central East Kunlun Fault zone.

Synthesis of TiCr2 intermetallic compound from mechanically activated starting powders via calcio-thermic co-reduction

NASA Astrophysics Data System (ADS)

Bayat, O.; Khavandi, A. R.; Ghasemzadeh, R.

2017-05-01

Effect of mechanical activation of TiO2 and Cr2O3 oxides as starting materials was investigated for direct synthesis of TiCr2. Differential thermal analysis (DTA) indicated that increasing the ball milling time resulted in lower exothermic reaction temperatures between molten Ca-Cr2O3 and molten Ca-TiO2. A model-free Kissinger type method was applied to DTA data to evaluate the reaction kinetics. The results reveal that the activation energy of the exothermic reactions decreased with increasing the milling time. The structure, oxygen content, and average particle sizes of the obtained TiCr2 product were affected by the ball milling time of the starting materials. Increasing the milling time from 10 to 40 h decreased the average particle size and oxygen content of the obtained TiCr2 from 10 to 2 μm and from 1690 to 1290 ppm, respectively. The X-ray diffraction (XRD) results showed that TiCr2 compounds with metastable bcc phase can be produced using nano-sized starting materials, while only a slight amount of bcc phase can be obtained in the TiCr2 compounds, using micron-sized starting materials. The TiCr2 obtained by this method had a hydrogen absorption capability of 0.63 wt % and the kinetics of the hydrogen absorption increased for the 40 h milled sample.

Remotely Delivered Exercise-Based Cardiac Rehabilitation: Design and Content Development of a Novel mHealth Platform

PubMed Central

Gant, Nicholas; Meads, Andrew; Warren, Ian; Maddison, Ralph

2016-01-01

Background Participation in traditional center-based cardiac rehabilitation exercise programs (exCR) is limited by accessibility barriers. Mobile health (mHealth) technologies can overcome these barriers while preserving critical attributes of center-based exCR monitoring and coaching, but these opportunities have not yet been capitalized on. Objective We aimed to design and develop an evidence- and theory-based mHealth platform for remote delivery of exCR to any geographical location. Methods An iterative process was used to design and develop an evidence- and theory-based mHealth platform (REMOTE-CR) that provides real-time remote exercise monitoring and coaching, behavior change education, and social support. Results The REMOTE-CR platform comprises a commercially available smartphone and wearable sensor, custom smartphone and Web-based applications (apps), and a custom middleware. The platform allows exCR specialists to monitor patients’ exercise and provide individualized coaching in real-time, from almost any location, and provide behavior change education and social support. Intervention content incorporates Social Cognitive Theory, Self-determination Theory, and a taxonomy of behavior change techniques. Exercise components are based on guidelines for clinical exercise prescription. Conclusions The REMOTE-CR platform extends the capabilities of previous telehealth exCR platforms and narrows the gap between existing center- and home-based exCR services. REMOTE-CR can complement center-based exCR by providing an alternative option for patients whose needs are not being met. Remotely monitored exCR may be more cost-effective than establishing additional center-based programs. The effectiveness and acceptability of REMOTE-CR are now being evaluated in a noninferiority randomized controlled trial. PMID:27342791

[Structure and luminescence properties of Ga2O3 : Cr3+ by Al doping].

PubMed

Wang, Xian-Sheng; Wan, Min-Hua; Wang, Yin-Hai; Zhao, Hui; Hu, Zheng-Fa; Li, Hai-Ling

2013-11-01

The Al doping gallate phosphor (Ga(1-x)Al(x))2O3 : Cr3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by a high temperature solid-state reaction method. The X-ray diffractions show that the phase of the phosphors remains to be Ga2 O3 structure with increase in the contents of Al3+ ion. Beside, the fact that the X-ray diffraction peak shifts towards big angles with increasing Al3+ ions content shows that Al3+ ions entered the Ga2 O3 lattice. The peaks of the excitation spectra located at 258, 300, 410 and 550 nm are attributed to the band to band transition of the matrix, charge transfer band transition, and 4A2 --> 4T1 and 4A2 --> 4T2 transition of Cr3+ ions, respectively. Those excitation spectrum peak positions show different degrees of blue shift with the increase in the Al3+ ions content. The blue shift of the first two peaks are due to the band gap energy of substrate and the electronegativity between Cr3+ ions and ligands increasing, respectively. The blue shift of the energy level transition of Cr3+ ion is attributed to crystal field strength increasing. The Cr3+ ion luminescence changes from a broadband emission to a narrow-band emission with Al3+ doping, because the emission of Cr3+ ion changed from 4 T2 --> 4A2 to 2E --> 4A2 transition with the crystal field change after Al3+ ions doping. The Al3+ ions doping improved the long afterglow luminescence properties of samples, and the sample showed a longer visible near infrared when Al3+ ions content reaches 0.5. The thermoluminescence curve shows the sample with suitable trap energy level, and this is also the cause of the long afterglow luminescence materials.

Using precipitated Cr on the surface of Cu-Cr alloy powders as catalyst synthesizing CNTs/Cu composite powders by water-assisted CVD

NASA Astrophysics Data System (ADS)

Zhou, Honglei; Liu, Ping; Chen, Xiaohong; Bi, Liming; Zhang, Ke; Liu, Xinkuan; Li, Wei; Ma, Fengcang

2018-02-01

Given that the conventional catalyst is easily soluble in the matrix to result in the poor performance of the CNTs/Cu composite materials, the Cr nano-particles precipitated on the surface of Cu-Cr particles are first used as catalysts to prepare the CNTs/Cu composite powders by means of water-assisted chemical vapor deposition in situ synthesis. The results show that the morphological difference of the precipitated Cr nano-particle is obvious with the change of solution and aging treatment, and the morphology, length and diameter of the synthetic CNTs are also different. The catalyst of Cr nano-particle has the best morphology and the synthesized CNTs had a good wettability with Cu particles when the Cu-Cr composite powders was solution-treated at 1023 K for 60 min and then was aged at 723 K for 120 min. The length, diameter, yield and purity of the synthesized CNTs can be also affected by the moisture content in the reaction gas. It is the most suitable for the growth of CNTs when the moisture content is 0.4%, and the high purity and defect-free CNTs with the smooth pipe wall, a diameter of 20 ˜ 30 nm and a length of up to 1800 nm can be obtained. The yield of CNTs with the moisture content of 0.4% reached to 138%, which was increased by 119% to compare with that without moisture. In this paper, a feasible technology was offered for the preparation of high performance CNTs/Cu composites.

Hair geochemical composition of children from Vilnius kindergartens as an indicator of environmental conditions.

PubMed

Taraškevičius, Ričardas; Zinkutė, Rimantė; Gedminienė, Laura; Stankevičius, Žilvinas

2017-05-23

The research is based on analysis data of Cr, Cu, Mn, Ni, V, Zn (metals) and S in the hair of 47 girls and 63 boys from eight Vilnius kindergartens and the distribution pattern of high metal concentrations and bioavailability in snow-cover dust, also dust samples from vents of characteristic pollution sources. The kindergartens were selected according to topsoil total contamination index and dust-related indices. Significantly higher Cu, Mn, Ni and Zn concentrations in the hair of girls (means are 1.1, 1.9, 1.3, 1.2 times higher) and the differences between hair of genders according to inter-element correlation and clustering were found. Analysis of Spearman correlation coefficients between metal concentrations in hair of each gender and dust metal concentrations or metal loading rates at their residence sites revealed that for Mn, Cu and Zn, they are insignificant, while for Cr, Ni, Pb and V, they are mainly significant positive (except V in female hair). The correlation of the contents of Cr, Ni and V in dust with respective concentrations in hair was more significant for boys (p < 0.001) than for girls. Only a few cases with a significant Cr, Ni, Cu, Pb and Zn increase were revealed in hair of children attending polluted kindergartens in comparison with control. It was concluded that relationship between metal concentrations in hair and dust-related indices is more expressed for children's residence sites than for their kindergarten sites. The gender-based grouping and site-by-site study design are recommended in the studies of reflection of environmental exposure in hair.

Optimization of TiNP/Ti Content for Si3N4/42CrMo Joints Brazed With Ag-Cu-Ti+TiNP Composite Filler

NASA Astrophysics Data System (ADS)

Wang, Tianpeng; Zhang, Jie; Liu, Chunfeng

The Si3N4 ceramic was brazed to 42CrMo steel by using TiN particles modified braze, and the proportion of TiNp reinforcement and active element Ti was optimized to improve the joint strength. The brazed joints were examined by means of SEM. and EDS investigations. Microstructural examination showed that TiN+Ti5Si3 reaction layer was adjacent to Si3N4, whereas TiC was formed in 42CrMo/filler reaction layer. The Ag-Cu-Ti brazing alloy showed intimate bonding with TiNp and Cu-Ti intermetallics precipitated in the joint. The strength tests demonstrated that the mechanical properties of joints increased and then decreased by increasing the TiNp content when a low Ti content (6wt.%) was supplied. When the Ti content (>6wt.%) was offered sufficiently, the joint strength decreased firstly and then stayed stable with increasing the TiNp content. The maximum four-point bending strength (221 MPa) was obtained when the contents of TiNp and Ti were 10vol.% and 6wt.%, respectively.

Effects of spin entropy and lattice strain from mixed-trivalent Fe3+/Cr3+ on the electronic, thermoelectric and optical properties of delafossite CuFe1-x Cr x O2 (x  =  0.25, 0.5, 0.75)

NASA Astrophysics Data System (ADS)

Ruttanapun, Chesta; Maensiri, Santi

2015-12-01

Mixed-trivalent Fe3+/Cr3+ content CuFe1-x Cr x O2 (x  =  0.25, 0.5, and 0.75) compounds were synthesized to investigate the effects of spin entropy, and lattice strain on their electronic, thermoelectric and optical properties. The XPS results showed the existence of mixed Cu1+/Cu2+, Fe3+/Fe4+ and Cr2+/Cr3+ ion states in the structures. The mixed Fe3+/Cr3+ions caused a strong correlation to occur between the spin and the orbitals of the carriers in the octahedral layer of the sample, affecting the carrier degeneracy Seebeck coefficient behaviour, and the Cu2+ and Fe4+ ions caused an effect of enhancing the electric conductivity. These effects meant that CuFe0.75Cr0.25O2 had the highest electrical conductivity, an enhanced Seebeck coefficient compared to that of CuFeO2-based compounds, and the highest thermopower value. The lowest thermal conductivity was that of CuFe0.5Cr0.5O2, which was a result of the mismatched atomic radii of the mixed trivalent Fe3+(0.645 Å)/Cr3+(0.615 Å), which caused the lattice strain to occur in the structure and thus affected the point defect scattering of the phonon thermal conductivity. The lowest total thermal conductivity was that of CuFe0.5Cr0.5O2, because it had the maximum lattice strain. Overall, the effect of the mixed trivalent elements caused CuFe0.75Cr0.25O2 to have the highest value of the dimensionless figure of merit ZT, with a value that was four times that of CuFeO2-based compounds and six times that of CuCrO2-based compounds. With regard to optical properties, the lattice strain causes the indirect optical gap to increase with increasing x content, but has no effect on the direct optical gap. These results verified that the mixed-trivalent Fe3+/Cr3+ content of CuFe1-x Cr x O2 (x  =  0.25, 0.5, and 0.75) affected the electronic, thermoelectric and optical properties of the structure by causing spin entropy and lattice strain to occur.

Response of antioxidants in sunflower (Helianthus annuus L.) grown on different amendments of tannery sludge: its metal accumulation potential.

PubMed

Singh, Shraddha; Saxena, Rohit; Pandey, Kavita; Bhatt, Kavita; Sinha, Sarita

2004-12-01

The interaction of metals present in tannery waste and their tolerance in the plants of sunflower (Helianthus annuus L.) was studied in the present paper under field conditions. Effects of 100% tannery sludge and various amendments of tannery sludge (10%, 25%, 35%, 50%, 75%) along with one set of control were studied on the physiological and biochemical parameters of the plant along with their metal accumulation potential after 30, 60 and 90d after sowing. The plants of H. annuus were found effective in the accumulation of metals (Cr, Fe, Zn and Mn) in roots, shoots and leaves, however, the level of toxic metal, Cr was found below detection limit in the seeds of the plant. The oil was extracted from the seeds of the plant and the level of oil content was increased up to 35% tannery sludge as compared to control followed by decrease at higher tannery sludge ratio. An increase in the chlorophyll, protein, cysteine, non-protein thiol and sugar contents was observed at the lower amendment of tannery sludge at initial exposure periods followed by decrease than their respective controls. Malondialdehyde content in the roots and leaves was increased beyond 50% sludge amendments at all the exposure periods as compared to control. However, proline and ascorbic acid contents of the roots and leaves of the plant increased at all the exposure periods and sludge amendments, compared to their respective controls.

Occupational Exposure to Chromium of Assembly Workers in Aviation Industries.

PubMed

Genovese, G; Castiglia, L; Pieri, M; Novi, C; d'Angelo, R; Sannolo, N; Lamberti, M; Miraglia, N

2015-01-01

Aircraft are constructed by modules that are covered by a "primer" layer, which can often contain hexavalent chromium [Cr(VI)], known carcinogen to humans. While the occupational exposure to Cr(VI) during aircraft painting is ascertained, the exposure assessment of assembly workers (assemblers) requires investigations. Three biological monitoring campaigns (BM-I,II,III) were performed in an aviation industry, on homogeneous groups of assemblers (N = 43) and controls (N = 23), by measuring chromium concentrations in end-shift urine collected at the end of the working week and the chromium concentration difference between end- and before-shift urines. BM-I was conducted on full-time workers, BM-II was performed on workers after a 3-4 day absence from work, BM-III on workers using ecoprimers with lower Cr(VI) content. Samples were analyzed by atomic absorption spectroscopy and mean values were compared by T-test. Even if Cr concentrations measured during BM-I were lower than Biological Exposure Indices by ACGIH, statistically significant differences were found between urinary Cr concentrations of workers and controls. Despite 3-4 days of absence from work, urinary chromium concentrations measured during BM-II were still higher than references from nonoccupationally exposed populations. In the BM-III campaign, the obtained preliminary results suggested the efficacy of using ecoprimers. The healthcare of workers exposed to carcinogenic agents follows the principle of limiting the exposure to "the minimum technically possible". The obtained results evidence that assemblers of aviation industries, whose task does not involve the direct use of primers containing Cr(VI), show an albeit slight occupational exposure to Cr(VI), that must be carefully taken into consideration in planning suitable prevention measures during risk assessment and management processes.

Multivariate analysis of selected metals in tannery effluents and related soil.

PubMed

Tariq, Saadia R; Shah, Munir H; Shaheen, N; Khalique, A; Manzoor, S; Jaffar, M

2005-06-30

Effluent and relevant soil samples from 38 tanning units housed in Kasur, Pakistan, were obtained for metal analysis by flame atomic absorption spectrophotometric method. The levels of 12 metals, Na, Ca, K, Mg, Fe, Mn, Cr, Co, Cd, Ni, Pb and Zn were determined in the two media. The data were evaluated towards metal distribution and metal-to-metal correlations. The study evidenced enhanced levels of Cr (391, 16.7 mg/L) and Na (25,519, 9369 mg/L) in tannery effluents and relevant soil samples, respectively. The effluent versus soil trace metal content relationship confirmed that the effluent Cr was strongly correlated with soil Cr. For metal source identification the techniques of principal component analysis, and cluster analysis were applied. The principal component analysis yielded two factors for effluents: factor 1 (49.6% variance) showed significant loading for Ca, Fe, Mn, Cr, Cd, Ni, Pb and Zn, referring to a tanning related source for these metals, and factor 2 (12.6% variance) with higher loadings of Na, K, Mg and Co, was associated with the processes during the skin/hide treatment. Similarly, two factors with a cumulative variance of 34.8% were obtained for soil samples: factor 1 manifested the contribution from Mg, Mn, Co, Cd, Ni and Pb, which though soil-based is basically effluent-derived, while factor 2 was found associated with Na, K, Ca, Cr and Zn which referred to a tannery-based source. The dendograms obtained from cluster analysis, also support the observed results. The study exhibits a gross pollution of soils with Cr at levels far exceeding the stipulated safe limit laid down for tannery effluents.

Optimization of Superaustenitic Stainless Steel Filler Metals for Welding Advanced Double Hull Combatant Ships

DTIC Science & Technology

2005-02-16

alloy is also given. The solidification mode of martensitic samples has been omitted and replaced with ’M’. Mo Ni +Cr Cr Ni ... alloys composed predominately of austenite. The four solidification modes present in the remaining 64 alloys , in order of increasing Cr/ Ni content, were...result in Fe- Ni -Cr-Mo alloys from the arc-melt condition. Solidification Solidification Primar- Secondar- Final microstrncture Mode

Effect of CrO3 Sealing Time on Anodized A12024-T3

NASA Astrophysics Data System (ADS)

Korda, Akhmad A.; Hidayat, R. Z.

2016-08-01

The effect of CrO3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO3 sealing was conducted in CrO3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO3 sealing were compared. The highest hardness is achieved by CrO3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration.

Distribution of chromium species in a Cr-polluted soil: presence of Cr(III) in glomalin related protein fraction.

PubMed

Gil-Cardeza, María L; Ferri, Alejandro; Cornejo, Pablo; Gomez, Elena

2014-09-15

The accumulation of Cr in soil could be highly toxic to human health; therefore Cr soil distribution was studied in rhizosphere soils from Ricinus communis and Conium maculatum and bare soil (BS) from an industrial and urban area in Argentina. Total Cr, Cr(VI) and Cr(III) concentrations were determined in 3 soil fractions: total, extractable and associated to total-glomalin-related protein (T-GRSP). BS had the highest total Cr and total Cr(VI) concentrations. Total Cr(VI) concentration from both rhizosphere soils did not differ from the allowed value for residential area in Argentina (8 μg Cr(VI) g(-1) soil), while total Cr(VI) in BS was 1.8 times higher. Total Cr concentration in all the soils was higher than the allowed value (250 μg Cr g(-1) soil). Extractable and associated to T-GRSP Cr(VI) concentrations were below the detection limit. Cr(III) bound to T-GRSP was the highest in the BS. These findings are in agreement with a long term effect of glomalin in sequestrating Cr. In both plant species, total Cr was higher in root than in shoot and both species presented arbuscular mycorrhizal fungi (AMF). As far as we know, this is the first study that reports the presence of Cr in T-GRSP fraction of soil organic matter. These findings suggest that Cr mycorrhizostabilization could be a predominant mechanism used by R. communis and C. maculatum to diminish Cr soil concentration. Nevertheless, further research is needed to clarify the contribution of native AMF isolated from R. communis and C. maculatum rhizosphere to the Cr phytoremediation process. Copyright © 2014 Elsevier B.V. All rights reserved.

Geochemical studies of Fe, Mn, Co, As, Cr, Sb, Zn, Sc and V in surface sediments from Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Wu, Run; Li, Pei-Quan; Miao, Lu-Tian; Zhang, Shu-Xin; Tian, Wei-Zhi

1994-12-01

The contents of nearly forty-elements in surface sediments in Jiaozhou Bay were determined using a Neutron Activation Analysis Technique (Grancini, et al., 1976; Li Peiquan et al., 1985, 1986; Li Xiuxia et al., 1986). This paper's detailed discussion on only nine elements (Fe, Mn, Co, Cr, Sc, As, Sb, Zn and V) includes their distributions, concentrations, correlationships, material sources, background, etc. Based on Zavaristski's classification method, Fe, Mn, Co, Cr and V belong to the second group; As and Sb to the eighth groups: Sc and Zn to the third and sixth groups. It was found that their notably good correlationship is mainly due to the similarity of their ionic structures and that their variation is controlled by the Fe content (except Mn). The source of sediments is mainly terristrial material, and the composition of sediment is similar to that of shale and shale+clay. The contents for a large number of elements are within the scope of the background level, but there still is pollution of Zn and Cr, at least in a few stations.

Transfer of immunoglobulins through the mammary endothelium and epithelium and in the local lymph node of cows during the initial response after intramammary challenge with E. coli endotoxin.

PubMed

Ostensson, Karin; Lun, Shichun

2008-07-02

The first hours after antigen stimulation, interactions occur influencing the outcome of the immunological reaction. Immunoglobulins originate in blood and/or are locally synthesized. The transfer of Ig isotypes (Igs) in the udder has been studied previously but without the possibility to distinguish between the endothelium and the epithelium. The purpose of this study was to map the Ig transfer through each barrier, separately, and Ig transfer in the local lymph nodes of the bovine udder during the initial innate immune response. The content of IgG1, IgG2, IgM, IgA and albumin (BSA) was examined in peripheral/afferent mammary lymph and lymph leaving the supramammary lymph nodes, and in blood and milk before (0 h) and during 4 hours after intramammary challenge with Esherichia coli endotoxin in 5 cows. Igs increased most rapidly in afferent lymph resulting in higher concentrations than in efferent lymph at postinfusion hour (PIH) 2, contrary to before challenge. Ig concentrations in milk were lower than in lymph; except for IgA at 0 h; and they increased more slowly. Afferent lymph:serum and efferent lymph:serum concentration ratios (CR) of Igs were similar to those of BSA but slightly lower. Milk:afferent lymph (M:A) CRs of each Ig, except for IgG2, showed strikingly different pattern than those of BSA. The M:A CR of IgG1, IgM and IgA were higher than that of BSA before challenge and the CR of IgA and IgG1 remained higher also thereafter. At PIH 2 there was a drop in Ig CRs, except for IgG2, in contrast to the BSA CR which gradually increased. The M:A CR of IgM and Ig A decreased from 0 h to PIH 4, in spite of increasing permeability. The transfer of Igs through the endothelium appeared to be merely a result of diffusion although their large molecular size may hamper the diffusion. The transfer through the epithelium and the Ig concentrations in milk seemed more influenced by selective mechanisms and local sources, respectively. Our observations indicate a selective mechanism in the transfer of IgG1 through the epithelium also in lactating glands, not previously shown; a local synthesis of IgA and possibly of IgM, released primarily into milk, not into tissue fluid; that IgG2 transfer through both barriers is a result of passive diffusion only and that the content of efferent lymph is strongly influenced by IgG1, IgM and IgA in the mammary tissue, brought to the lymph node by afferent lymph.

Transfer of immunoglobulins through the mammary endothelium and epithelium and in the local lymph node of cows during the initial response after intramammary challenge with E. coli endotoxin

PubMed Central

Östensson, Karin; Lun, Shichun

2008-01-01

Background The first hours after antigen stimulation, interactions occur influencing the outcome of the immunological reaction. Immunoglobulins originate in blood and/or are locally synthesized. The transfer of Ig isotypes (Igs) in the udder has been studied previously but without the possibility to distinguish between the endothelium and the epithelium. The purpose of this study was to map the Ig transfer through each barrier, separately, and Ig transfer in the local lymph nodes of the bovine udder during the initial innate immune response. Methods The content of IgG1, IgG2, IgM, IgA and albumin (BSA) was examined in peripheral/afferent mammary lymph and lymph leaving the supramammary lymph nodes, and in blood and milk before (0 h) and during 4 hours after intramammary challenge with Esherichia coli endotoxin in 5 cows. Results Igs increased most rapidly in afferent lymph resulting in higher concentrations than in efferent lymph at postinfusion hour (PIH) 2, contrary to before challenge. Ig concentrations in milk were lower than in lymph; except for IgA at 0 h; and they increased more slowly. Afferent lymph:serum and efferent lymph:serum concentration ratios (CR) of Igs were similar to those of BSA but slightly lower. Milk:afferent lymph (M:A) CRs of each Ig, except for IgG2, showed strikingly different pattern than those of BSA. The M:A CR of IgG1, IgM and IgA were higher than that of BSA before challenge and the CR of IgA and IgG1 remained higher also thereafter. At PIH 2 there was a drop in Ig CRs, except for IgG2, in contrast to the BSA CR which gradually increased. The M:A CR of IgM and Ig A decreased from 0 h to PIH 4, in spite of increasing permeability. Conclusion The transfer of Igs through the endothelium appeared to be merely a result of diffusion although their large molecular size may hamper the diffusion. The transfer through the epithelium and the Ig concentrations in milk seemed more influenced by selective mechanisms and local sources, respectively. Our observations indicate a selective mechanism in the transfer of IgG1 through the epithelium also in lactating glands, not previously shown; a local synthesis of IgA and possibly of IgM, released primarily into milk, not into tissue fluid; that IgG2 transfer through both barriers is a result of passive diffusion only and that the content of efferent lymph is strongly influenced by IgG1, IgM and IgA in the mammary tissue, brought to the lymph node by afferent lymph. PMID:18597683

Effect of alkaline precipitation on Cr species of Cr(III)-bearing complexes typically used in the tannery industry.

PubMed

Wang, Dandan; Ye, Yuxuan; Liu, Hui; Ma, Hongrui; Zhang, Weiming

2018-02-01

Various organic compounds extensively used in the leather industry could influence the performance of alkaline precipitation with Cr(III). This study focused on two typical Cr(III)-bearing complexes (Cr(III)-collagen and Cr(III)-citrate) ubiquitous in tannery effluent yet with distinct treatment efficiencies, as Cr(III) was much more difficult to remove in the Cr(III)-citrate solution. Comprehensive analytical methods were employed to explore the intrinsic mechanism. It was found that a lower removal efficiency towards Cr(III) was significantly associated with higher oligomers. The molecular size of the Cr(III)-citrate complex continued to increase with rising pH, making it larger overall than Cr(III)-collagen species. The growing oligomer moiety of dissolved Cr(III)-complex species could persist in the stronger basic pH range, leading to the large amount of residual Cr(III) in the Cr(III)-citrate system. Combining this result with potentiometric titration and X-ray photoelectron spectroscopy data, it was believed that the polymeric species other than monomers facilitated resisting the attack from hydroxide ions, and the postulated Cr(III)-citrate species towards higher oligomers were discovered. Beyond that, both charge neutralization and sweeping effects were presented among the gradually emerging flocs in the Cr(III)-collagen system together with the electric double layer compression effect derived from salinity, thus resulting in a larger floc size and higher Cr(III) removal efficiency in saline solutions. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Structure and luminescence properties of MgGa2O4 : Cr3+ with Zn substituted for Mg].

PubMed

Zhang, Wan-Xin; Wang, Yin-Hai; Li, Hai-Ling; Wang, Xian-Sheng; Zhao, Hui

2013-01-01

A series of red long afterglow phosphors with composition Zn(x) Mg(1-2) Ga2 O4 : Cr3+ (x = 0, 0.2, 0.6, 0.8, 1.0) were synthesized by a high temperature solid-state reaction method. The X-ray diffraction studies show that the phase of the phosphors is face-centered cubic structure. Photoluminescence spectra show that the red emission of Cr3+ originated from the transition of 2E-4A2. Due to the large overlap between absorption band of Cr3+ and emission band of the host. Cr3+ could obtain the excitation energy from the host via the effective energy transfer. The afterglow decay characteristics show that the phosphor samples with different Zn contents have different afterglow time and the afterglow time also changes with the value of x. The measurement of thermoluminescence reveals that the trap depth of the phosphor samples with different Zn contents is different. The samples with deeper traps have longer afterglow time.

Dislocation loop formation in model FeCrAl alloys after neutron irradiation below 1 dpa

DOE PAGES

Field, Kevin G.; Briggs, Samuel A.; Sridharan, Kumar; ...

2017-08-01

FeCrAl alloys with varying compositions and microstructures are under consideration for accident-tolerant fuel cladding, but limited details exist on dislocation loop formation and growth for this class of alloys under neutron irradiation. Four model FeCrAl alloys with chromium contents ranging from 10.01 to 17.51 wt % and alunimum contents of 4.78 to 2.93 wt % were neutron irradiated to doses of 0.3–0.8 displacements per atom (dpa) at temperatures of 335–355°C. On-zone STEM imaging revealed a mixed population of black dots and larger dislocation loops with either a/2< 111 > or a< 100 > Burgers vectors. Weak composition dependencies were observedmore » and varied depending on whether the defect size, number density, or ratio of defect types was of interest. Here, the results were found to mirror those of previous studies on FeCrAl and FeCr alloys irradiated under similar conditions, although distinct differences exist.« less

Dislocation loop formation in model FeCrAl alloys after neutron irradiation below 1 dpa

NASA Astrophysics Data System (ADS)

Field, Kevin G.; Briggs, Samuel A.; Sridharan, Kumar; Yamamoto, Yukinori; Howard, Richard H.

2017-11-01

FeCrAl alloys with varying compositions and microstructures are under consideration for accident-tolerant fuel cladding, but limited details exist on dislocation loop formation and growth for this class of alloys under neutron irradiation. Four model FeCrAl alloys with chromium contents ranging from 10.01 to 17.51 wt % and aluminum contents of 4.78 to 2.93 wt % were neutron irradiated to doses of 0.3-0.8 displacements per atom (dpa) at temperatures of 335-355 °C. On-zone STEM imaging revealed a mixed population of black dots and larger dislocation loops with either a / 2 〈 111 〉 or a 〈 100 〉 Burgers vectors. Weak composition dependencies were observed and varied depending on whether the defect size, number density, or ratio of defect types was of interest. Results were found to mirror those of previous studies on FeCrAl and FeCr alloys irradiated under similar conditions, although distinct differences exist.

Accumulation and detoxification dynamics of Chromium and antioxidant responses in juvenile rare minnow, Gobiocypris rarus.

PubMed

Yuan, Cong; Li, Meng; Zheng, Yao; Zhou, Ying; Wu, Feili; Wang, Zaizhao

2017-09-01

Hexavalent chromium (Cr 6+ ) compounds are hazardous via all exposure routes. To explore the dynamics of Cr accumulation and elimination and to reveal the mechanisms underlying detoxification and antioxidation in juvenile Gobiocypris rarus, one-month old G. rarus larvae were exposed to 0.1mgL -1 Cr 6+ for four weeks for accumulation and subsequently placed to clean water for another week for depuration. The contents of Cr were measured weekly in the whole body of G. rarus juveniles. The activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST) and glutathione reductase (GR), and contents of glutathione (GSH) and malonaldehyde (MDA), and transcripts of cat, Cu/Zn-sod, Mn-sod, gpx1, gstpi, gr, mt1, nrf2 and uba52 were determined. The results indicated that G. rarus juveniles had a strong ability to resist the Cr accumulation by Cr 6+ exposure and to remove Cr from the body in clean water. In addition, GST and MT proteins may be involved in the detoxification of Cr 6+ . Moreover, Cr 6+ -induced GST detoxification in G. rarus juveniles might be accomplished through the Nrf2-mediated regulation of gene expressions. The antioxidant enzyme systems exhibited a response mechanism of the protective enzymes in organisms when they are subjected to external environmental stress. Two weeks of Cr 6+ treatments could have led to the damage and consecutive degradation of antioxidant enzymes via ubiquitination, and MT proteins could be involved in protecting the activity of these enzymes. The capability of antioxidant enzyme systems to recover from the Cr 6+ -induced damage was strong in G. rarus juveniles after Cr 6+ was removed from the water. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of compound carboxylate-urea system on nano Ni-Cr/SiC composite coatings from trivalent chromium baths.

PubMed

He, Xinkuai; Hou, Bailong; Cai, Youxing; Wu, Luye

2013-03-01

The effects of compound carboxylate-urea system on the nano Ni-Cr/SiC composite coatings from trivalent chromium baths have been investigated in ultrasonic field. These results indicated that the SiC and Cr contents and the thickness of the Ni-Cr/SiC composite coatings could be obviously improved by the compound carboxylate-urea system. The steady-state polarization curves showed that the hydrogen evolution reaction (HER) could be significantly inhibited by the compound carboxylate-urea system, which was benefit to increase the SiC and Cr contents and the thickness of the composite coatings. The cyclic voltammetry (CV) curves showed that both of the Cr(III) and Ni(II) cathodic polarization could be increased in the bath containing the compound carboxylate-urea system. Thus, a compact Ni-Cr/SiC composite coating could be obtained using this technique. The surface morphology of the Ni-Cr/SiC composite coatings checked with the scanning electron micrographs (SEM) showed that the surface smoothness could be also improved and the microcracks and pinholes could be decreased due to the presence of the compound carboxylate-urea system. The phase composition of the as-posited coating was measured by the X-ray diffraction. XRD data showed that the as-posited coating was Ni-Cr/SiC composite coating. The chemical composition of the coating was investigated by energy dispersive spectrum (EDS) analysis. The result showed the Ni-Cr/SiC composite coatings with 3.8 wt.% SiC and 24.68 wt.% Cr were obtained in this study, which had best corrosion resistance according to the results of the typical potentiodynamic polarization curves of the Ni-Cr/SiC composite coatings.

Occupational exposure to Cr(VI): comparison between chromium levels in lymphocytes, erythrocytes, and urine.

PubMed

Lukanova, A; Toniolo, P; Zhitkovich, A; Nikolova, V; Panev, T; Popov, T; Taioli, E; Costa, M

1996-01-01

The relationships between chromium (Cr) levels in lymphocytes, erythrocytes, urine, and ambient air were compared among 14 chrome-platers from a metallurgic plant in Bulgaria and two groups of local controls, one from the same heavily polluted industrial town as the chrome-platers (n = 11) and one from a seaside resort town 100 km away (n = 6). Among the chrome-platers, the Cr concentration in peripheral lymphocytes was positively correlated with total Cr and Cr(VI) levels in ambient air and with Cr excretion in urine. As compared to the controls, the chrome-platers had mean Cr levels in lymphocytes twice as high, in erythrocytes ninefold higher, and in urine fourfold to eightfold higher. Although Cr levels in urine and lymphocytes were similar between the two control groups, levels in erythrocytes were 3 times higher among subjects from the industrial area than among those from the seaside town. The study suggests that lymphocyte Cr could be a good indicator of the Cr body burden caused by high exposures to Cr(VI), such as in electroplating operations. In these conditions, erythrocyte Cr may be less useful, possibly owing to increased toxicity due to the high affinity of erythrocytes for Cr. However, when exposure is lower, such as in most environmental situations, erythrocyte Cr should provide a better and more sensitive index than lymphocyte Cr. By contrast, urinary Cr, which provides information on total Cr exposure, including Cr(III) from dietary and environmental sources, does not seem to be of value for studying occupational exposure to Cr(VI).

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part I - Impurity effects and solidifcation mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.

For laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steels, the relationship between solidification cracking susceptibility and chemical composition was examined, and primary solidification mode (PSM) diagrams were developed to predict solidification mode. Sigmajig testing was used with experimental heats of type 21-6-9 to determine the effect of P and S on solidification cracking w hen primary austenite solidification occurred. Phosphorus showed a larger influence on solidification cracking relative to S, and a relationship of (P+0.2S ) was found for total impurity content. PSM diagrams to predict solidification mode were developed by analyzing welds made at three travel speeds for a widemore » range of 21-6-9 alloys and some other similar alloys. The minimum Cr eq/Ni eq required for primary ferrite solidification increased as travel speed increased, with more alloys showing primary austenite solidification at higher travel rates. Furthermore, as travel speed increased from 21 to 85 mm/s, the average solidification rate increased from 6 to 25 mm/s.« less

Laser weldability of 21Cr-6Ni-9Mn stainless steel: Part I - Impurity effects and solidifcation mode

DOE PAGES

Tate, Stephen B.; Javernick, Daniel Anthony; Lienert, Thomas J.; ...

2016-11-02

For laser welded type 21Cr-6Ni-9Mn (21-6-9) stainless steels, the relationship between solidification cracking susceptibility and chemical composition was examined, and primary solidification mode (PSM) diagrams were developed to predict solidification mode. Sigmajig testing was used with experimental heats of type 21-6-9 to determine the effect of P and S on solidification cracking w hen primary austenite solidification occurred. Phosphorus showed a larger influence on solidification cracking relative to S, and a relationship of (P+0.2S ) was found for total impurity content. PSM diagrams to predict solidification mode were developed by analyzing welds made at three travel speeds for a widemore » range of 21-6-9 alloys and some other similar alloys. The minimum Cr eq/Ni eq required for primary ferrite solidification increased as travel speed increased, with more alloys showing primary austenite solidification at higher travel rates. Furthermore, as travel speed increased from 21 to 85 mm/s, the average solidification rate increased from 6 to 25 mm/s.« less

Corrosion behavior of ODS steels with several chromium contents in hot nitric acid solutions

NASA Astrophysics Data System (ADS)

Tanno, Takashi; Takeuchi, Masayuki; Ohtsuka, Satoshi; Kaito, Takeji

2017-10-01

Oxide dispersion strengthened (ODS) steel cladding tubes have been developed for fast reactors. Tempered martensitic ODS steels with 9 and 11 wt% of chromium (9Cr-, 11Cr-ODS steel) are the candidate material in research being carried out at JAEA. In this work, fundamental immersion tests and electrochemical tests of 9 to 12Cr-ODS steels were systematically conducted in various nitric acid solutions at 95 °C. The corrosion rate decreased exponentially with effective solute chromium concentration (Creff) and nitric acid concentration. Addition of vanadium (V) and ruthenium (Ru) also decreased the corrosion rate. The combination of low Creff and dilute nitric acid could not avoid the active mass dissolution during active domain at the beginning of immersion, and the corrosion rate was high. Higher Creff decreased the partial anodic current during the active domain and assisted the passivation of the surface of the steel. Concentrated nitric acid and addition of Ru and V increased partial cathodic current and shifted the corrosion potential to noble side. These effects should have prevented the active mass dissolution and decreased the corrosion rate.

The Colony meteorite and variations in CO3 chondrite properties

NASA Technical Reports Server (NTRS)

Rubin, A. E.; James, J. A.; Keck, B. D.; Weeks, K. S.; Sears, D. W. G.

1985-01-01

The Colony meteorite is one of the least equilibrated CO3 chondrites, yet differs from normal CO chondrites in that, while Al, Sc, V, Cr, Ir, Fe, Au, and Ga abundances are consistent with a CO chondrite classification, certain lithophile, siderophile, and chalcophile contents are depleted by factors of 10-40 percent. Colony is badly weathered, and its Fe, Ni abundance of about 19 wt pct is similar to that of the Kainsaz CO3 unweathered fall but higher than all other CO3 chondrites.

Evaluation of aquifer environment under Hazaribagh leather processing zone of Dhaka city

NASA Astrophysics Data System (ADS)

Zahid, Anwar; Balke, K.-D.; Hassan, M. Qumrul; Flegr, Matthias

2006-07-01

Hazaribagh is a densely populated area of Dhaka city where about 185 leather processing industries have been operating and discharging solid and liquid wastes directly to the low-lying areas, river and natural canals without proper treatment. The area is covered by alluvial deposits of Holocene age and is underlain by Pleistocene Madhupur clay. The Dupi Tila Formation of Mio-Pliocene age underlain by this yellowish gray to brick red clay bed serves as the main water-bearing aquifer of Dhaka city. To assess the environmental degradation as well as the groundwater environment, major anions, cations and heavy metals of water samples, heavy metals and organic carbon content of sediment samples were analyzed in this study. Analyses of tannery effluent detect high concentration of Na+, Mg2+, Cl- and SO{4/2-} followed by Ca2+, NH{4/+} and K+ with remarkable contents of some trace elements, mainly Cr, Fe, Mn, S, Ni and Pb. Higher accumulations of Cr, Al and Fe are observed in topsoil samples with significant amounts of Mn, Zn, Ni and Cu. Concentrations of ions and all the investigated trace elements of sampled groundwater were within the maximum allowable limit for drinking water of the Department of Environment, Bangladesh (DoE), and World Health Organization (WHO). However, excessive concentrations of Cr, Pb, etc., have already been reported in the shallow groundwater (10-20 m) of the area. Due to excessive withdrawal the vulnerability of groundwater contamination in deeper parts cannot be avoided for the future.

Effects of Heat Treatments and Compositional Modification on Carbide Network and Matrix Microstructure in Ultrahigh Carbon Steels

NASA Astrophysics Data System (ADS)

Hecht, Matthew David

This dissertation investigates microstructure/property relations in ultrahigh carbon steel (UHCS) with the aim of improving toughness while retaining high hardness. Due to high C contents (ranging from 1 to 2 wt%), UHCS exhibit high strength, hardness, and wear resistance. Despite this, applications for UHCS are currently limited because they typically contain a continuous network of proeutectoid cementite that greatly reduces ductility and toughness. In previous research, thermomechanic processing had seen considerable success in breaking up the network. However, the processing is difficult and has thus far seen very limited industrial application. Chemical modification of the steel composition has also seen some success in network break-up, but is still not well understood. There have been relatively few fundamental studies of microstructure evolution in UHCS; studies in the literature typically focused on lower C steels (up to 1 wt% C) or on cast irons (>2.1 wt% C). Thus, this work was undertaken to gain a better understanding of microstructural changes that occur during heat treatment and/or chemical modification of UHCS with a focus on the distribution of proeutectoid cementite within the microstructure. This dissertation is composed of eight chapters. The first chapter presents an introduction to phases found in UHCS, descriptions of research materials used in each chapter, and the hypotheses and objectives guiding the work. The second chapter describes a study of the microstructure found in a 2C-4Cr UHCS before and after an industrial-scale austenitizating heat treatment that increased hardness and toughness and also produced discrete carbide particles in the matrix. The third chapter establishes and demonstrates a metric for measuring connectivity in carbide networks. The fourth chapter describes a series of heat treatments designed to investigate kinetics of spheroidization and coarsening of carbide particles and denuded zones near cementite network branches in 2C-4Cr UHCS. The fifth chapter describes an additional series of heat treatments comparing coarsening kinetics in 2C-1Cr and 2C-4Cr UHCS. Lowering the Cr content caused clustering of cementite particles near grain boundaries, in contrast to the denuded zones observed in the higher Cr UHCS. The fifth chapter details four in situ confocal laser scanning microscopy heat treatments of 2C-4Cr UHCS. The seventh chapter investigates the effects of a 2wt% Nb addition on 2C-4Cr UHCS. The eighth and final chapter summarizes the findings of all the experiments of the previous chapters and revisits the objectives and conclusions.

Growth performance and carcass characteristics of growing ram lambs fed sweet sorghum bagasse-based complete rations varying in roughage-to-concentrate ratios.

PubMed

Kumari, Nagireddy Nalini; Reddy, Yerradoddi Ramana; Blummel, Michel; Nagalakshmi, Devanaboyina; Monika, Thamatam; Reddy, Belum Venkata Subba; Reddy, Chintalapani Ravinder

2013-02-01

Different roughage-to-concentrate ratios of sweet sorghum bagasse (SSB) (a by-product of the biofuel industry)-based complete diets were assessed. Twenty four growing Nellore × Deccani ram lambs aged about 3 months (average body wt., 10.62 ± 0.25 kg) were randomly allotted to four complete rations (CR) varying in roughage-to-concentrate ratios viz. 60:40 (CR-I), 50:50 (CR-II), 40:60 (CR-III) and 30:70(CR-IV) for a period of 180 days. The feed intake was comparable among the lambs fed different experimental complete diets. Average daily weight gain (in grams) was 77.31 ± 4.90, 81.76 ± 5.16, 85.83 ± 2.83 and 86.30 ± 3.25, and feed conversion ratio (in kilograms of feed per kilogram gain) averaged 11.42 ± 0.68, 10.57 ± 0.64, 10.17 ± 0.37 and 9.96 ± 0.38 in ram lambs fed CR-I, CR-II, CR-III and CR-IV rations, respectively. Statistically, differences in daily weight gain and feed conversion ratio among the lambs fed four experimental rations were not significant (P > 0.05). The cost per kilogram gain was significantly (P < 0.01) higher in ram lambs fed CR-IV and CR-III rations compared to CR-I ration, and it was comparable between CR-I and CR-II rations. Dressing percentage averaged 44.90 ± 0.15, 42.57 ± 0.72, 43.67 ± 0.16 and 44.42 ± 0.76 for the respective diets. No significant difference and trend was observed in preslaughter weight, empty body weight, carcass weights, dressing percentage, wholesale cuts and edible and non-edible portions of experimental animals. Similarly, no significant variation could be seen in bone and meat yield (in per cent) and their ratios in various wholesale cuts among the dietary treatments. The roughage-to-concentrate ratio did not affect the chemical composition of meat; however, the fat content of meat was linearly increased with increase in the proportion of concentrate in the diets. The results of the experiment indicated that SSB can be included at 60 % level in the complete diet for economical mutton production from growing Nellore × Deccani ram lambs.

X-Ray Photoelectron Study of the Oxides Formed on Nickel Metal and Nickel-Chromium 20% Alloy Surfaces Under Reducing and Oxidizing Potentials in Basic, Neutral and Acidic Solutions

NASA Astrophysics Data System (ADS)

Payne, Brad P.; Keech, Peter G.; McIntyre, N. Stewart

The corrosion products produced on polycrystalline Ni metal and Ni-Cr (20%) (NiCr) alloy surfaces exposed to aqueous environments chosen to emulate possible solution conditions in the steam generator (SG) tubing of pressurized water reactors (PWR) were studied using XPS. Additional measurements modelling the distribution of oxidized Ni and Cr species on select alloy specimens were carried out using ToF SIMS. Exposure of Ni metal and NiCr alloy samples to mildly oxidizing potentials in basic solutions resulted in the preferential growth of a β-Ni(OH)2 phase; driven by the dissolution of metallic Ni at both 25°C and 150°C. The presence of β-Ni(OH)2, Cr(OH)3 and small amounts of a Cr6+-containing oxide on NiCr specimens oxidized under mildly oxidizing conditions at 150°C in neutral solutions suggested that the dissolution of both metallic Ni and Cr followed by the back deposition of the corresponding corrosion products was responsible for oxide growth under these conditions. In acidic media oxide nucleation at 150°C under mildly oxidizing potentials was determined to occur via the dissolution of both Ni and Cr species on NiCr specimens as well. The increased stability of Ni2+ in acidic solution led to a limited precipitation of β-Ni(OH)2 resulting in the formation of very thin oxides containing higher levels of Cr(OH)3. Reactions on metallic Ni and NiCr surfaces under highly oxidizing potentials resulted in an increase in the NiO content of these films compared to similar exposures carried out at milder oxidation conditions attributed to accelerated dehydration of the β-Ni(OH)2 phase. In addition, an increase in the Cr(OH)3 contribution on the alloy surface oxidized at a more oxidative potential suggested a more rapid dissolution of Cr under these conditions; overall, uneven films were formed from these conditions. The composition of the corrosion product formed after an exposure to a highly oxidizing potential was found to be unchanged following a subsequent reaction of equivalent length at a much lower oxidizing potential in basic solution.

Translation, Cross-cultural Adaptation and Psychometric Validation of the Korean-Language Cardiac Rehabilitation Barriers Scale (CRBS-K).

PubMed

Baek, Sora; Park, Hee-Won; Lee, Yookyung; Grace, Sherry L; Kim, Won-Seok

2017-10-01

To perform a translation and cross-cultural adaptation of the Cardiac Rehabilitation Barriers Scale (CRBS) for use in Korea, followed by psychometric validation. The CRBS was developed to assess patients' perception of the degree to which patient, provider and health system-level barriers affect their cardiac rehabilitation (CR) participation. The CRBS consists of 21 items (barriers to adherence) rated on a 5-point Likert scale. The first phase was to translate and cross-culturally adapt the CRBS to the Korean language. After back-translation, both versions were reviewed by a committee. The face validity was assessed in a sample of Korean patients (n=53) with history of acute myocardial infarction that did not participate in CR through semi-structured interviews. The second phase was to assess the construct and criterion validity of the Korean translation as well as internal reliability, through administration of the translated version in 104 patients, principle component analysis with varimax rotation and cross-referencing against CR use, respectively. The length, readability, and clarity of the questionnaire were rated well, demonstrating face validity. Analysis revealed a six-factor solution, demonstrating construct validity. Cronbach's alpha was greater than 0.65. Barriers rated highest included not knowing about CR and not being contacted by a program. The mean CRBS score was significantly higher among non-attendees (2.71±0.26) than CR attendees (2.51±0.18) (p<0.01). The Korean version of CRBS has demonstrated face, content and criterion validity, suggesting it may be useful for assessing barriers to CR utilization in Korea.

Influence of parasitism on trace element contents in tissues of red fox (Vulpes vulpes) and its parasites Mesocestoides spp. (Cestoda) and Toxascaris leonina (Nematoda).

PubMed

Jankovská, Ivana; Miholová, Daniela; Bejcek, Vladimír; Vadlejch, Jaroslav; Sulc, Miloslav; Száková, Jirina; Langrová, Iva

2010-02-01

Bioaccumulation of cadmium, chromium, copper, manganese, nickel, lead, and zinc in 56 foxes (Vulpes vulpes) and their parasites Mesocestoides spp. (Cestoda) and Toxascaris leonina (Nematoda) was studied. The levels of heavy metals were determined in the livers and kidneys of the animals depending on parasitism in the following ranges: Pb, 0.029-3.556; Cd, 0.055-9.967; Cr, 0.001-0.304; Cu, 4.15-41.15; Mn, 1.81-19.94; Ni: 0.037-0.831; Zn, 52.0-212.9 microg/g dry weight (dw). Cd in parasites (0.038-3.678 microg/g dw) were comparable with those in the livers of the host and lower than in the kidneys (0.095-6.032 microg/g dw). Contents of Pb, Cr, Cu, Mn, Ni, and Zn in cestodes were predominantly higher than those in the kidney and liver of the host. Median lead levels in Mesocestoides spp. (45.6 microg/g dw) were 52-fold higher than in the kidney and liver of the red fox (Vulpes vulpes) infected by both parasites and median Pb values in T. leonina (8.98 microg/g dw) were 8-fold higher than in the tissues of the parasitized red fox. Bioaccumulation factors of copper, zinc, nickel, and manganese are lower than those of lead and mostly range from 1.9 to 24 for Mesocestoides spp. and from 1.5 to 6 for nematode T. leonina depending on the tissue of host and element. A significant decrease in the content of Pb was found in the kidney of animals infected by T. leonina (0.260 microg/g dw) as well as those infected by Mesocestoides spp. (0.457 microg/g dw) in comparison with the lead content (0.878 microg/g dw) in the kidneys of the nonparasitized red fox. Regardless of a bioaccumulation of copper and manganese in the parasites, a significant increase of the concentrations of Mn and Cu was observed in the host's livers infected predominantly by Mesocestoides spp.

Bacterial Cr(VI) reduction concurrently improves sunflower (Helianthus Annuus L.) growth.

PubMed

Faisal, Muhammad; Hasnain, Shahida

2005-07-01

Four Cr(VI)-reducing bacterial strains (Ochrobactrum intermedium, CrT-2, CrT-3 and CrT-4) previously isolated from chromium-contaminated sites were inoculated on to seeds of sunflower (Helianthus annuus var SF-187), which were germinated and grown along with non-inoculated controls with chromate salts (300 microg CrCl3 or K2CrO4 ml(-1)). Severe reduction (20%) in seed germination was observed in Cr(VI) stress. Plant height decreased (36%) with Cr(VI) when compared with chromium-free control, while O. intermedium inoculation resulted a 20% increment in this parameter as compared to non-inoculated chromium-free control. CrT-3 inoculation resulted a 69% increment in auxin content as compared to non-inoculated control. O. intermedium caused 30% decrease in chromium uptake in sunflower plant roots under Cr(VI) stress as compared to chromium-free control plants.

Comparison of Mineral Element Content in a Functional Food Maca (Lepidium meyenii Walp.) from Asia and South America

PubMed Central

Zhang, Ji; Wang, Han-Mo; Zhao, Yan-Li; Zuo, Zhi-Tian; Wang, Yuan-Zhong

2015-01-01

Contents of eight mineral elements in maca (Lepidium meyenii Walp.) from China and Peru were determined by inductively coupled plasma optical emission spectroscopy. Cu contents in maca samples from China (2.5–31 mg kg−1 dry weight, dw) were higher than the samples from Peru (<2.1 mg kg−1 dw). Na in two samples from China was found to be significantly of high content (2400 and 2600 mg kg−1 dw). The contents (mg kg−1 dw) of B, Co, Cr, Li, Ni, and Zn were, respectively, 8.1–21, <0.023, <1.1~3.5, 0.020–0.17, 0.085–4.5, and 10–39 for the samples from China, while being 6.6–12, <0.023, <1.1~2.3, 0.035–0.063, 0.68–1.7, and 27–39 for the samples from Peru. PMID:26236540

Synthesis and characterization of CrCN-DLC composite coatings by cathodic arc ion-plating

NASA Astrophysics Data System (ADS)

Wang, R. Y.; Wang, L. L.; Liu, H. D.; Yan, S. J.; Chen, Y. M.; Fu, D. J.; Yang, B.

2013-07-01

CrCN-DLC composite coatings were deposited onto silicon (1 0 0) and cemented carbides substrates using pure Cr targets under C2H2 ambient by cathodic arc ion plating system. The influence of C2H2 flow rate on the structure and mechanical properties of the coatings was investigated systemically. The coatings structure and bonding state were characterized by XRD, Raman and X-ray photoelectron spectroscopy. The chemical composition was measured by EDS. The mechanical performance and tribological behaviour of the coatings were studied by a hardness tester and ball-on-disc wear tester. The results showed that with increasing C2H2 flow rate from 50 to 100 sccm, the corresponding hardness of coatings increased firstly and then decreased with further addition of C2H2 flow rate. The coatings deposited at lower C2H2 flow rate (less than 200 sccm) exhibited a relatively higher hardness value (more than HV0.0252000) and then the hardness decrease with increasing C2H2 flow rate. The friction coefficient also exhibited similar variation trend, when the C2H2 flow rate was higher than 100 sccm, the friction coefficient decreased and then maintained in a relatively lower value from 0.18 to 0.24, which may be attribute to the increasing carbon content and the coating exhibited more diamond-like structure.

Tensile properties of chrome tanned leather waste short fibre filled unsaturated polyester composite

NASA Astrophysics Data System (ADS)

Talib, Satariah; Romli, Ahmad Zafir; Saad, Siti Zaleha

2017-12-01

Waste leather from industries was commonly disposed via land filling or incineration where the oxidation of Cr III to Cr VI by oxidants (such as peroxides and hypohalide) can easily occur. Cr VI is well known as carcinogenic and mutagenic element where the excessive exposure to this element can be very harmful. As an alternative way, the leather waste from footwear industry was utilised as filler in unsaturated polyester composite (UPC). The leather waste was ground using 0.25 mm mesh size and used without any chemical treatment. The sample was fabricated via castingtechnique and the study was carried out at 1 wt%, 2 wt% and 3 wt% filler loading. The leather waste filled composites showed lower tensile strength and Young's modulus than the unfilled composite. The increasing loading amount of leather waste led to the decreased in tensile strength and Young's modulus. The tensile results was supported by the decreasing pattern of density result which indicates the increasing of void content as the filler loading increased. The results of glass transition temperature are also parallel to the tensile properties where the increasing filler loading had decreased the glass transition temperature. Based on the morphological observation on the fractured tensile sample, much severe filler agglomerations and higher amount of voids was observed at higher filler loading compared to the lower filler loading.

Effect of Al content on structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yurchenko, N.Yu.

2016-11-15

In present study, structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys after arc melting and annealing at 1200 °C for 24 h are investigated. The CrNbTiVZr alloy is composed of body centered cubic (bcc) and C15 (face centered cubic) Laves phases while the Al{sub x}CrNbTiVZr (x = 0.25; 0.5; 1) alloys consist of bcc and two C14 (hexagonal close packed) Laves phases with different chemical compositions. Thermodynamic modeling predicts existence of two phases – bcc and C15 Laves phase and broadening of single bcc phase field due to Al addition. The densitymore » of the alloys decreases with the increase of Al content. The alloys are found to be extremely brittle at room temperature and 600 °C. The alloys have high strength at temperatures of 800–1000 °C. For example, yield strength at 800 °C increases from 440 MPa for the CrNbTiVZr alloy to 1250 MPa for the AlCrNbTiVZr alloy. The experimental phase composition of the Al{sub x}CrNbTiVZr alloys is compared with predicted equilibrium phases and the factors governing the transformation of C15 to C14 Laves phases due to Al addition to the CrNbTiVZr alloy analyzed. Specific properties of the alloys are compared with other high-entropy alloys and commercial Ni-based superalloys. - Highlights: •Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) alloys are arc melted and annealed at 1200 °C. •The CrNbTiVZr alloy has bcc and C15 Laves phases. •The Al-containing alloys are composed of bcc and two C14 Laves phases. •The alloys demonstrate high specific strength at temperatures of 800 °C and 1000 °C. •The strength of the alloys increases in proportion with increase of Al content.« less

Analysis of physical composition and heavy metals pollution of municipal solid waste (MSW) in Beijing

NASA Astrophysics Data System (ADS)

Zhang, H. B.; Zhang, H. Y.; Wang, G. Q.; Bai, X. J.

2018-03-01

By using on-site sampling and physical-chemical analysis, the physical composition and the contents of heavy metals in Beijing MSW were researched. The result showed that the main components of MSW in Beijing are mainly kitchen waste, the average content of kitchen waste are more than 60% and 50% in summer and in winter, respectively. The pollution of Cu, Hg and Cr are all more serious for MSW in Haidian and Dongcheng district. The heavy metal pollution of MSW in summer is higher than that in winter in Beijing. Seasonal impacts should be taken into consideration when dealing with MSW. The content of heavy metals in MSW exceeded the background value of soil in Haidian and Dongcheng districts. In order to reduce heavy metal pollution, the MSW should be separated collection and treated.

Long term high temperature oxidation characteristics of La and Cu alloyed ferritic stainless steels for solid oxide fuel cell interconnects

NASA Astrophysics Data System (ADS)

Swaminathan, Srinivasan; Lee, Young-Su; Kim, Dong-Ik

2016-09-01

To ensure the best performance of solid oxide fuel cell metallic interconnects, the Fe-22 wt.% Cr ferritic stainless steels with various La contents (0.006-0.6 wt.%) and Cu addition (1.57 wt.%), are developed. Long-term isothermal oxidation behavior of these steels is investigated in air at 800 °C, for 2700 h. Chemistry, morphology, and microstructure of the thermally grown oxide scale are examined using XPS, SEM-EDX, and XRD techniques. Broadly, all the steels show a double layer consisting of an inner Cr2O3 and outer (Mn, Cr)3O4. Distinctly, in the La-added steels, binary oxides of Cr, Mn and Ti are found at the oxide scale surface together with (Mn, Cr)3O4. Furthermore, all La-varied steels possess the metallic Fe protrusions along with discontinuous (Mn, Cr)3O4 spinel zones at the oxide scale/metal interface and isolated precipitates of Ti-oxides in the underlying matrix. Increase of La content to 0.6 wt.% is detrimental to the oxidation resistance. For the Cu-added steel, Cu is found to segregate strongly at the oxide scale/metal interface which inhibits the ingress of oxygen thereby suppressing the subscale formation of (Mn, Cr)3O4. Thus, Cu addition to the Fe-22Cr ferritic stainless steels benefits the oxidation resistance.

Trace metal contents in wild edible mushrooms growing on serpentine and volcanic soils on the island of Lesvos, Greece.

PubMed

Aloupi, M; Koutrotsios, G; Koulousaris, M; Kalogeropoulos, N

2012-04-01

The objectives of this survey were (1) to assess for the first time the Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn contents in wild edible mushrooms (Russula delica, Lactarius sanguifluus, Lactarius semisanguifluus, Lactarius deliciosus, Suillus bellinii) from the island of Lesvos, (2) to investigate the metals' variability among the species, as well as in relation to the chemical composition of the underlying soil, comparing mushrooms collected from volcanic and serpentine substrates and (3) to estimate metal intake by the consumption of the mushrooms under consideration. The trace metals in 139 samples were determined by flame or flameless atomic absorption spectroscopy. The median metal concentrations were as follows: Cd: 0.14; Cr: 0.10; Cu: 8.51; Fe: 30.3; Mn: 5.26; Ni: 0.34; Pb: 0.093 and Zn: 64.50, all in mgkg(-1) dry weight. The observed concentrations are among the lowest reported for mushrooms from Europe or Turkey, while Pb and Cd values did not exceed the limits set by the European Union. Significant species- and substrate-related differences in the metal contents were found, but the variability did not follow a uniform pattern for all the metals in all mushroom species. As a general trend, the mushrooms growing in serpentine sites contained higher Cd, Cr and Ni than those from volcanic sites. The calculated bioconcentration factors (BCFs) showed that none of the mushrooms can be regarded as a metal bioaccumulator, although BCF values slightly above unity were found for Zn in the three Lactarius species, and for Cu in R. delica. The studied mushrooms could supply considerable amounts of essential metals such as Zn and Cr. On the other hand, the consumption of R. delica collected from volcanic soils could provide 12% of the Cd daily tolerable intake and as high as 53% when collected from serpentine soils. Nonetheless, our results indicate that the regular consumption of wild edible mushrooms from Lesvos is quite safe for human health. Copyright © 2011 Elsevier Inc. All rights reserved.

Chromium Extraction via Chemical Processing of Fe-Cr Alloys Fine Powder with High Carbon Content

NASA Astrophysics Data System (ADS)

Torres, D. M.; Navarro, R. C. S.; Souza, R. F. M.; Brocchi, E. A.

2017-06-01

Ferrous alloys are important raw materials for special steel production. In this context, alloys from the Fe-Cr system, with typical Cr weight fraction ranging from 0.45 to 0.95, are prominent, particularly for the stainless steel industry. During the process in which these alloys are obtained, there is considerable production of fine powder, which could be reused after suitable chemical treatment, for example, through coupling pyrometallurgical and hydrometallurgical processes. In the present study, the extraction of chromium from fine powder generated during the production of a Fe-Cr alloy with high C content was investigated. Roasting reactions were performed at 1073 K, 1173 K, and 1273 K (800 °C, 900 °C, and 1000 °C) with 300 pct (w/w) excess NaOH in an oxidizing atmosphere (air), followed by solubilization in deionized water, selective precipitation, and subsequent calcination at 1173 K (900 °C) in order to convert the obtained chromium hydroxide to Cr2O3. The maximum achieved Cr recovery was around 86 pct, suggesting that the proposed chemical route was satisfactory regarding the extraction of the chromium initially present. Moreover, after X-ray diffraction analysis, the final produced oxide has proven to be pure Cr2O3 with a mean crystallite size of 200 nm.

Intranasal Chromium Induces Acute Brain and Lung Injuries in Rats: Assessment of Different Potential Hazardous Effects of Environmental and Occupational Exposure to Chromium and Introduction of a Novel Pharmacological and Toxicological Animal Model.

PubMed

Salama, Abeer; Hegazy, Rehab; Hassan, Azza

2016-01-01

Chromium (Cr) is used in many industries and it is widely distributed in the environment. Exposure to Cr dust has been reported among workers at these industries. Beside its hazardous effects on the lungs, brain injury could be induced, as the absorption of substances through the nasal membrane has been found to provide them a direct delivery to the brain. We investigated the distribution and the effects of Cr in both brain and lung following the intranasal instillation of potassium dichromate (inPDC) in rats. Simultaneously, we used the common intraperitoneal (ipPDC) rat model of acute Cr-toxicity for comparison. Thirty male Wistar rats were randomly allocated into five groups (n = 6); each received a single dose of saline, ipPDC (15 mg/kg), or inPDC in three dose levels: 0.5, 1, or 2 mg/kg. Locomotor activity was assessed before and 24 h after PDC administration, then, the lungs and brain were collected for biochemical, histopathological, and immunohistochemical investigations. Treatment of rats with ipPDC resulted in a recognition of 36% and 31% of the injected dose of Cr in the brain and lung tissues, respectively. In inPDC-treated rats, targeting the brain by Cr was increased in a dose-dependent manner to reach 46% of the instilled dose in the group treated with the highest dose. Moreover, only this high dose of inPDC resulted in a delivery of a significant concentration of Cr, which represented 42% of the instilled dose, to the lungs. The uppermost alteration in the rats locomotor activity as well as in the brain and lung histopathological features and contents of oxidative stress biomarkers, interleukin-1β (IL-1β), phosphorylated protein kinase B (PKB), and cyclooxygenase 2 (COX-2) were observed in the rats treated with inPDC (2 mg/kg). The findings revealed that these toxic manifestations were directly proportional to the delivered concentration of Cr to the tissue. In conclusion, the study showed that a comparably higher concentrations of Cr and more elevated levels of oxidative stress and inflammatory markers were observed in brain and lung tissues of rats subjected to inPDC in a dose that is just 0.13 that of ipPDC dose commonly used in Cr-induced toxicity studies. Therefore, the study suggests a high risk of brain-targeting injury among individuals environmentally or occupationally exposed to Cr dust, even in low doses, and an additional risk of lung injury with higher Cr concentrations. Moreover, the study introduces inPDC (2 mg/kg)-instillation as a new experimental animal model suitable to study the acute brain and lung toxicities induced by intranasal exposure to Cr compounds.

Intranasal Chromium Induces Acute Brain and Lung Injuries in Rats: Assessment of Different Potential Hazardous Effects of Environmental and Occupational Exposure to Chromium and Introduction of a Novel Pharmacological and Toxicological Animal Model

PubMed Central

Salama, Abeer; Hassan, Azza

2016-01-01

Chromium (Cr) is used in many industries and it is widely distributed in the environment. Exposure to Cr dust has been reported among workers at these industries. Beside its hazardous effects on the lungs, brain injury could be induced, as the absorption of substances through the nasal membrane has been found to provide them a direct delivery to the brain. We investigated the distribution and the effects of Cr in both brain and lung following the intranasal instillation of potassium dichromate (inPDC) in rats. Simultaneously, we used the common intraperitoneal (ipPDC) rat model of acute Cr-toxicity for comparison. Thirty male Wistar rats were randomly allocated into five groups (n = 6); each received a single dose of saline, ipPDC (15 mg/kg), or inPDC in three dose levels: 0.5, 1, or 2 mg/kg. Locomotor activity was assessed before and 24 h after PDC administration, then, the lungs and brain were collected for biochemical, histopathological, and immunohistochemical investigations. Treatment of rats with ipPDC resulted in a recognition of 36% and 31% of the injected dose of Cr in the brain and lung tissues, respectively. In inPDC-treated rats, targeting the brain by Cr was increased in a dose-dependent manner to reach 46% of the instilled dose in the group treated with the highest dose. Moreover, only this high dose of inPDC resulted in a delivery of a significant concentration of Cr, which represented 42% of the instilled dose, to the lungs. The uppermost alteration in the rats locomotor activity as well as in the brain and lung histopathological features and contents of oxidative stress biomarkers, interleukin-1β (IL-1β), phosphorylated protein kinase B (PKB), and cyclooxygenase 2 (COX-2) were observed in the rats treated with inPDC (2 mg/kg). The findings revealed that these toxic manifestations were directly proportional to the delivered concentration of Cr to the tissue. In conclusion, the study showed that a comparably higher concentrations of Cr and more elevated levels of oxidative stress and inflammatory markers were observed in brain and lung tissues of rats subjected to inPDC in a dose that is just 0.13 that of ipPDC dose commonly used in Cr-induced toxicity studies. Therefore, the study suggests a high risk of brain-targeting injury among individuals environmentally or occupationally exposed to Cr dust, even in low doses, and an additional risk of lung injury with higher Cr concentrations. Moreover, the study introduces inPDC (2 mg/kg)-instillation as a new experimental animal model suitable to study the acute brain and lung toxicities induced by intranasal exposure to Cr compounds. PMID:27997619

The Relationship of Thioredoxin-1 and Cisplatin Resistance: Its Impact on ROS and Oxidative Metabolism in Lung Cancer Cells

PubMed Central

Wangpaichitr, Medhi; Theodoropoulos, George; Wu, Chunjing; You, Min; Feun, Lynn G.; Kuo, Macus T.; Savaraj, Niramol

2012-01-01

Elimination of cisplatin resistant (CR) lung cancer cells remains a major obstacle. We have shown that CR tumors have higher reactive oxygen species (ROS) levels and can be exploited for targeted therapy. Here we show that increased secretion of the antioxidant thioredoxin-1 (TRX1) resulted in lowered intracellular TRX1, and contributed to higher ROS in CR tumors in vivo and in vitro. By reconstitutingTRX1 protein in CR cells, we increased sensitivity to cisplatin but decreased sensitivity to elesclomol (ROS inducer). Conversely, decreased TRX1 protein in parental cells reduced the sensitivity to cisplatin but increased sensitivity to elesclomol. CR cells had increased endogenous oxygen consumption and mitochondrial activity but decreased lactic acid production. They also exhibited higher levels of argininosuccinate synthetase (ASS) and fumarase (FH) mRNA which contributed to oxidative metabolism (OXMET) when compared to parental cells. Restoring intracellular TRX1 protein in CR cells resulted in lowering ASS and FH mRNAs which in turn sensitized them to arginine deprivation. Interestingly, CR cells also possessed significantly higher basal levels of acetyl-CoA-carboxylase (ACC) and fatty acid synthase (FAS). Over-expressing TRX1 lowered ACC and FAS proteins expressions in CR cells. Chemical inhibition and siRNA of ACC resulted in significant cell death in CR compared to parental cells. Conversely, TRX1 over-expressed CR cells resisted to TOFA-induced death. Collectively, lowering TRX1 expression through increased secretion leads CR cells to higher ROS production and increase in dependency on OXMET. These changes raise an intriguing therapeutic potential for future therapy in cisplatin resistant lung cancer. PMID:22248473

Metal pollution and ecological risk assessment in marine sediments of Karachi Coast, Pakistan.

PubMed

Mashiatullah, Azhar; Chaudhary, Muhammad Zaman; Ahmad, Nasir; Javed, Tariq; Ghaffar, Abdul

2013-02-01

Concentrations of 12 metals (Fe, Mn, Cr, Mo, Ni, Pb, Se, Sr, U, V, Zn, and Zr) in surface sediments of Karachi Coast, Pakistan were determined to evaluate their distribution and pollution assessment. The measured metals in the sediments were found to be in the range of Fe, 0.84-6.96 %; Mn, 300-1,300 μg/g; Cr, 12.0-319.84 μg/g; Mo, 0.49-2.03 μg/g; Ni, 1.53-58.86 μg/g; Pb, 9.0-49.46 μg/g; Se, 0.25-.86 μg/g; Sr, 192-1185 μg/g; U, 0.19-1.66 μg/g; V, 15.80-118.20 μg/g; Zn, 15.60-666.28 μg/g; and Zr, 44.02-175.26 μg/g. The mean contents of the metal studied were: Fe, 3.07 %, Mn, 0.05 %; Cr, 96.75 μg/g; Mo, 1.34 μg/g; Ni, 31.39 μg/g; Pb, 23.24 μg/g; Se, 0.61 μg/g; Sr, 374.83 μg/g; U, 0.64 μg/g; V, 61.75 μg/g; Zn, 204.75 μg/g; and Zr:76.27 μg/g, and arrangement of the metals from higher to lower mean content in this area is: Fe > Zn > Mn > Sr > Zn > Cr > Zr > V > Ni > Pb > Mo > U > Se. There is no significant correlation among most of these metals, indicating different anthropogenic and natural sources. To assess ecotoxic potential of marine sediments, Numerical Sediment Quality Guidelines were also applied. The concentration of Pb in all the sediments except one was lower than the threshold effect concentration (TECs) showing that there are no harmful effects to marine life from Pb. On the other hand, the concentrations of Cr, Ni, and Zn exceeded TEC in three stations, indicating their potential risk. The degree of pollution in sediments for metals was assessed by calculating enrichment factor (EF) and pollution load index (PLI). The results indicated that sediments of Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are highly enriched with Cr and Zn (EF > 5). Sediments of Layari River Outfall Zone were moderately enriched with Ni and Pb (EF > 2). The pollution load index was found in the range of 0.98 to 1.34. Lower values of PLI (≤ 1) at most of sampling locations imply no appreciable input from anthropogenic sources. However, relatively higher PLI values (>1) at Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are attributed to increased human activity in the area.

Effect of macroalgae enriched with microelements on egg quality parameters and mineral content of eggs, eggshell, blood, feathers and droppings.

PubMed

Michalak, I; Chojnacka, K; Dobrzański, Z; Górecki, H; Zielińska, A; Korczyński, M; Opaliński, S

2011-06-01

This study presents results obtained from feeding experiment on laying hens, which were fed with the diet supplemented with two marine macroalgae: Enteromorpha prolifera and Cladophora sp., enriched with microelements [Cu(II), Zn(II), Co(II), Mn(II), Cr(III)]. The applicability of the preparation was tested on five experimental groups of laying hens and one control group. In the control group, microelements were supplemented in the inorganic form, whereas in experimental groups, Cu, Zn, Co, Mn and Cr were replaced by macroalgae enriched with a given microelement ion. During feeding experiment, weight of laying hens, weight of eggs, eggshell thickness and mineral content of blood, feathers, droppings, eggs content (separately yolk and egg white) and eggshell were measured. Also egg number was counted and microclimate (temperature and relative humidity) was monitored. Supplementing bio-metallic feed additives to the diet of laying hens resulted in higher microelement transfer to eggs and enhanced the colour of yolk. It was also found that the presence of Enteromorpha prolifera and Cladophora sp. in laying hens diet influenced advantageously eggs weight, eggshell thickness as well as body weight of hens. On the basis of these results, it could be concluded that Enteromorpha prolifera and Cladophora sp. enriched with microelement ions could be potentially used as mineral feed additives in laying hens feeding. © 2010 Blackwell Verlag GmbH.

Trivalent chromium alleviates oleic acid induced steatosis in SMMC-7721 cells by decreasing fatty acid uptake and triglyceride synthesis.

PubMed

Wang, Song; Wang, Jian; Zhang, Xiaonan; Hu, Linlin; Fang, Zhijia; Huang, Zhiwei; Shi, Ping

2016-10-01

Trivalent chromium [Cr(III)] has been shown as an essential trace element for human health. Previous studies depict that Cr(III) plays important roles in maintaining normal glucose and lipid metabolism, whereas its effect on the hepatic lipid metabolism is still unknown. In the present study, we investigated the effects and underlying mechanisms of Cr on hepatic steatosis induced by oleic acid (OA) in human hepatoma SMMC-7721 cells. Hepatic steatosis model was co-administered with Cr. Indexes of lipid accumulation were determined and associated genes expression were analyzed. The data showed that OA could induce lipid accumulation and triglyceride (TG) content in SMMC-7721 cells, and significantly increase the expression of cluster of differentiation 36 (CD36) and diacylglycerol acyltransferase 2 (DGAT2). This steatosis effect of OA was ameliorated by Cr. The TG accumulation and up-regulation of CD36 and DGAT2 genes followed steatosis induction were inhibited by Cr. After the treatment of Cr, excessive intracellular OA content was also attenuated. Furthermore, Cr still performed inhibitory effect of DGAT2 expression at the presence of DGAT2 agonist or inhibitor, which indicated that the inhibitory effect of Cr on lipogenesis is associated with the downregulation of DGAT2 expression. These findings demonstrate that Cr alleviates hepatic steatosis via suppressing CD36 expression to prevent fatty acid uptake, as well as suppressing DGAT2 expression to inhibit TG synthesis. It suggests that CD36 and DGAT2 might become the novel drug targets for their properties in hepatic steatosis. Most importantly, Cr may be a potential anti-steatosis candidate to offer protective effects against liver damage.

CO 2-rich komatiitic melt inclusions in Cr-spinels within beach sand from Gorgona Island, Colombia

NASA Astrophysics Data System (ADS)

Shimizu, Kenji; Shimizu, Nobumichi; Komiya, Tsuyoshi; Suzuki, Katsuhiko; Maruyama, Shigenori; Tatsumi, Yoshiyuki

2009-10-01

The volatile content of komatiite is a key to constrain the thermal and chemical evolution of the deep Earth. We report the volatile contents with major and trace element compositions of ~ 80 melt inclusions in chromian spinels (Cr-spinels) from beach sands on Gorgona Island, Colombia. Gorgona Island is a ~ 90 Ma volcanic island, where picrites and the youngest komatiites known on the Earth are present. Melt inclusions are classified into three types on the basis of their host Cr-spinel compositions: low Ti (P type), high Ti with high Cr # (K1 type) and high Ti with low Cr # (K2 type). Chemical variations of melt inclusions in the Cr-spinels cover all of the island's lava types. P-type inclusions mainly occur in the picrites, K1-type in high-TiO 2 komatiites (some enriched basalts: E-basalts) and K2-type in low-TiO 2 komatiites. The H 2O and CO 2 contents of melt inclusions within Cr-spinels from the beach sand are highly variable (H 2O: 0.03-0.9 wt.%; CO 2: 40-4000 ppm). Evaluation of volatile content is not entirely successful because of compositional alterations of the original melt by degassing, seawater/brine assimilation and post-entrapment modification of certain elements and volatiles. However, the occurrence of many melt inclusions with low H 2O/K 2O ratios indicates that H 2O/K 2O of Gorgona komatiite is not much different from that of modern mid-oceanic ridge basalt (MORB) or oceanic island basalt. Trend of CO 2/Nb and Zr/Y ratios, accounted for by two-component mixing between the least degassed primary komatiite and low-CO 2/Nb evolved basalt, allow us to estimate a primary CO 2/Nb ratio of 4000 ± 2200 or a CO 2 content of 0.16 ± 0.09 wt.%. The determined CO 2/Nb ratio is unusually high, compared to that of MORB (530). Although the presence of CO 2 in the Gorgona komatiite does not affect the magma generation temperature, CO 2 degassing may have contributed to the eruption of high-density magmas. High CO 2/Nb and the relatively anhydrous nature of Gorgona komatiite provide possible resolution to one aspect of the hydrous komatiite debate.

Response of Phase Transformation Inducing Heat Treatments on Microstructure and Mechanical Properties of Reduced Activation Ferritic-Martensitic Steels of Varying Tungsten Contents

NASA Astrophysics Data System (ADS)

Chandravathi, K. S.; Laha, Kinkar; Sasmal, C. S.; Parameswaran, P.; Nandagopal, M.; Tailor, H. M.; Mathew, M. D.; Jayakumar, T.; Rajendra Kumar, E.

2014-09-01

Microstructure and mechanical properties of 9Cr-W-0.06Ta Reduced Activation Ferritic-Martensitic (RAFM) steels having various tungsten contents ranging from 1 to 2 wt pct have been investigated on subjecting the steels to isothermal heat treatments for 5 minutes at temperatures ranging from 973 K to 1473 K (700 °C to 1200 °C) (below Ac1 to above Ac3) followed by oil quenching and tempering at 1033 K (760 °C) for 60 minutes. The steels possessed tempered martensite structure at all the heat-treated conditions. Prior-austenitic grain size of the steels was found to decrease on heating in the intercritical temperature range (between Ac1 and Ac3) and at temperatures just above the Ac3 followed by increase at higher heating temperatures. All the steels suffered significant reduction in hardness, tensile, and creep strength on heating in the intercritical temperature range, and the reduction was less for steel having higher tungsten content. Strength of the steels increased on heating above Ac3 and was higher for higher tungsten content. Transmission Electron Microscopy (TEM) investigations of the steels revealed coarsening of martensitic substructure and precipitates on heating in the intercritical temperature range, and the coarsening was relatively less for higher tungsten content steel, resulting in less reduction in tensile and creep strength on intercritical heating. Tensile and creep strengths of the steels at different microstructural conditions have been rationalized based on the estimated inter-barrier spacing to dislocation motion. The study revealed the uniqueness of inter-barrier spacing to dislocation motion in determining the strength of tempered martensitic steels subjected to different heat treatments.

Assessment of PM10 pollution level and required source emission reduction in Belgrade area.

PubMed

Todorović, Marija N; Perišić, Mirjana D; Kuzmanoski, Maja M; Stojić, Andreja M; Sostarić, Andrej I; Mijić, Zoran R; Rajšić, Slavica F

2015-01-01

The aim of this study was to assess PM10 pollution level and estimate required source emission reduction in Belgrade area, the second largest urban center in the Balkans. Daily mass concentrations and trace metal content (As, Cd, Cr, Mn, Ni, Pb) of PM10 were evaluated for three air quality monitoring sites of different types: urban-traffic (Slavija), suburban (Lazarevac) and rural (Grabovac) under the industrial influence, during the period of 2012-13. Noncompliance with current Air Quality Standards (AQS) was noticeable: annual means were higher than AQS at Slavija and Lazarevac, and daily frequency threshold was exceeded at all three locations. Annual means of As at Lazarevac were about four times higher than the target concentration, which could be attributed to the proximity of coal-fired power plants, and dust resuspension from coal basin and nearby ash landfills. Additionally, levels of Ni and Cr were significantly higher than in other European cities. Carcinogenic health risk of inhabitants' exposure to trace metals was assessed as well. Cumulative cancer risk exceeded the upper limit of acceptable US EPA range at two sites, with Cr and As as the major contributors. To estimate source emission reduction, required to meet AQS, lognormal, Weibull and Pearson 5 probability distribution, functions (PDF) were used to fit daily PM10 concentrations. Based on the rollback equation and best fitting PDF, estimated reduction was within the range of 28-98%. Finally, the required reduction obtained using two-parameter exponential distribution suggested that risks associated to accidental releases of pollutants should be of greater concern.

Electrical and magnetic properties of La0.67Ba0.33Mn1- x (Me) x O3 perovskite manganites: case of manganese substituted by trivalent (Me = Cr) and tetravalent (Me = Ti) elements

NASA Astrophysics Data System (ADS)

Oumezzine, Marwène; Peña, Octavio; Kallel, Sami; Kallel, Nabil; Guizouarn, Thierry; Gouttefangeas, Francis; Oumezzine, Mohamed

2014-03-01

The effects of non-magnetic Ti4+ substitution on the structural, electrical and magnetic properties of La0.67Ba0.33Mn1- x Ti x O3 (0≤ x≤0.1) are investigated and compared to those existing in La0.67Ba0.33Mn1- x Cr x O3 (magnetic Cr3+). The structural refinement by the Rietveld method revealed that Ti-doped samples crystallize in the cubic lattice with space group , while samples with Cr crystallize in the hexagonal setting of the rhombohedral space group for identical contents of dopant. The most relevant structural features are an increase of the lattice parameters, of the cell volume and of the inter-ionic distances with increasing Ti doping level. Both series of samples show a decrease of the paramagnetic-ferromagnetic transition temperature when the amount of chromium or titanium increases. Transport measurements show that when increasing the metal doping, the resistivity increases whereas the metallic behavior of the parent compound La0.67Ba0.33MnO3 is destroyed. For a substitution higher than 5 at.% of Ti and 10 at.% of Cr, the samples exhibit a semiconducting behavior in the whole range of temperature, for which the electronic transport can be explained by variable range hopping and/or small polaron hopping models.

A national survey of cardiac rehabilitation services in New Zealand: 2015.

PubMed

Kira, Geoff; Doolan-Noble, Fiona; Humphreys, Grace; Williams, Gina; O'Shaughnessy, Helen; Devlin, Gerry

2016-05-27

Guidelines for cardiac rehabilitation (CR) programmes inform best practice. In Aotearoa NewZealand, little information exists about the structure and services provided by CR programmes and there is a poor understanding of how existing CR programmes are delivered with respect to evidence-based national guidelines. All 46 CR providers in New Zealand were invited to participate in a national survey in 2015. The survey sought information on the following: unit structure; referral processes; patient assessment; audit (including quality assurance activity); Phase 2 CR content; and support for special populations. Simple descriptive analysis of the responses was conducted, involving forming counts and percentages. Thirty-six distinct units completed the survey and 94% provided Phase 2. Assessment tools, Phase 2 educational components, and the methods of providing the exercise component varied. Most units audited their services, 25% audited their programme six-monthly or more frequently. Just over half of the units (56%) reported key performance indicators. The survey identified variations in delivery and content of CR in New Zealand, with poor understanding of the impact on patient outcomes. This is likely due to the absence of standardised audit practices and routine collection of key performance indicators on a national basis.

The distribution of chromium among orthopyroxene, spinel and silicate liquid at atmospheric pressure

NASA Technical Reports Server (NTRS)

Barnes, S. J.

1986-01-01

The Cr distributions for a synthetic silicate melt equilibrated with bronzitic orthopyroxene and chromite spinel between 1334 and 1151 C over a range of oxygen fugacities between the nickel-nickel oxide and iron-wuestite buffers are studied. The occurrence, chemical composition, and structure of the orthopyroxene-silicate melt and the spinel-silicate melt are described. It is observed that the Cr content between bronzite and the melt increases with falling temperature along a given oxygen buffer and decreases with falling oxygen fugacity at a given temperature; however, the Cr content of the melt in equilibrium with spinel decreases with falling temperature and increases with lower oxygen fugacity.

Structural characterization of LiCrxMn2-xO4 via a simple reflux technique

NASA Astrophysics Data System (ADS)

Purwaningsih, Dyah; Roto, Roto; Sutrisno, Hari; Purwanto, Agus

2017-03-01

LiCrxMn2-xO4 (x=0; 0.02; 0.04; 0.06; 0.08, 0.10) have been successfully synthesized via a facile and simple reflux technique. The SEM-EDS data confirm the presence of Cr, Mn and O elements in the products, while the XRD pattern suggests that the materials have well-developed cubic crystals. Direct method was applied to extract structural parameters of LiCrxMn2-xO4 using the Fullprof and Oscail software in WinPlotr package program. Materials were refined in the crystal system, and space group of structures Fd3m phase were then identified. The lattice parameters decrease with the decrease in Cr content. The highest Li-O bond length was found for LiCr0.10Mn1.90O4. It was observed that there is no significant change in particle size as Cr content increased.

Influence of Chemical Composition and Heat Treatment Condition on Impact Toughness of 15Cr Ferritic Creep Resistant Steel

NASA Astrophysics Data System (ADS)

Toda, Yoshiaki; Tohyama, Hideaki; Kushima, Hideaki; Kimura, Kazuhiro; Abe, Fujio

Influences of chemical compositions, heat treatment and microstructure on impact toughness of 15Cr ferritic steel have been investigated. Charpy impact values of the furnace cooled steels were lower than 15J/cm2 at room temperature independent of chemical compositions. Drastic improvement in impact toughness has been attained by controlling the carbon and nitrogen contents, by the addition of nickel and by the increase in cooling rate after annealing. However, the effect of nickel on impact toughness strongly depends on carbon and nitrogen contents. Improvement in impact toughness of the 15Cr ferritic steel has not been explained by individual microstructural factors of grain size, distribution of precipitates, volume fraction of martensitic phase. It has been supposed that the increase in Charpy impact toughness of the 15Cr ferritic steel was attained by improvement in toughness of ferrite matrix itself.

Research on self-propagating high temperature synthesis prepared ZrC-ZrB2 composite ceramic

NASA Astrophysics Data System (ADS)

Yong, Cheng; Xunjia, Su; Genliang, Hou; YaKun, Xing

2013-03-01

ZrC-ZrB2 composite ceramic material is prepared by self-propagating high temperature synthesis, using Zr powders, CrO2 powders and Al powders as raw materials. Samples are studied by XRD and SEM, the results show that: ZrC-ZrB2 composite ceramic is attained after self-propagating high-temperature reaction, with Zr+ B4C as the main reactive system, and which is added respectively different content (CrO3 + Al) system. The study finds that the ceramic composite products are mainly composed of ZrC and ZrB2 phase, and other subphase. Compared to the main reactive system composite ceramic, composite ceramic grains grow up obviously, after introduction of the highly exothermic system (CrO3 + Al) in the main reactive system, and with the gradual increase of the content (CrO3 + Al).

Biomarkers of exposure to stainless steel tungsten inert gas welding fumes and the effect of exposure on exhaled breath condensate.

PubMed

Riccelli, Maria Grazia; Goldoni, Matteo; Andreoli, Roberta; Mozzoni, Paola; Pinelli, Silvana; Alinovi, Rossella; Selis, Luisella; Mutti, Antonio; Corradi, Massimo

2018-08-01

The respiratory tract is the main target organ of the inhaled hexavalent chromium (Cr-VI) and nickel (Ni) contained in stainless steel (SS) welding fumes (WFs). The aim of this study was to investigate the Cr and Ni content of the exhaled breath condensate (EBC) of SS tungsten inert gas (TIG) welders, and relate their concentrations with oxidative stress and inflammatory biomarkers. EBC and urine from 100 SS TIG welders were collected pre-(T 0 ) and post-shift (T 1 ) on a Friday, and pre-shift (T 2 ) on the following Monday morning. Both EBC and urinary Cr concentrations were higher at T 1 (0.08 μg/L and 0.71 μg/g creatinine) and T 0 (0.06 μg/L and 0.74 μg/g creatinine) than at T 2 (below the limit of detection [LOD] and 0.59 μg/g creatinine), and EBC Ni concentrations generally remained

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Williams; Zhao, Ji-Cheng

Cost effective and high performance alloys that are capable of operating at 760 °C or higher for extended periods of time under a very aggressive environment are critically required for the design and development of advanced ultrasupercritical (AUSC) boilers and steam turbines. Finely dispersed Laves phase precipitates have been shown by Takeyama and co-workers to be a viable strengthening mechanism in high temperature austenitic steels. There is currently no straightforward theory that can predict what other intermetallic phases can serve as potent precipitation-strengthening phases for steels; thus we employed a highly effective dual-anneal diffusion multiple (DADM) approach to screen formore » viable strengthening precipitates over a wide range of compositions. From the Fe-Co-Cr-Ni-Mo DADMs, the Fe-Cr-Mo based Chi phase was identified as a new strengthening phase for high temperature ferritic steels; and from the Fe-Mn-Cr-Nb-Ni-Mo-FeAl DADMs, the Laves phase was identified as a viable strengthening precipitate in Fe-Mn and Fe-Ni based austenitic steels. After identification of viable strengthening phases from the DADMs that covered compositions in the basic ternary and quaternary systems, we employed computation thermodynamics to perform multicomponent alloy design and optimization. For the new the Chi-phase strengthened steels, we performed thermodynamic calculations to vary the volume fraction of the Chi phase and introduced Nb and carbon to promote the formation of stable carbides for grain size control during solution heat treatment. For the Fe-Ni-Mn based austenitic steels, we performed extensive parametric optimization of compositions in order to reduce the expensive Ni content, add Cr and Al for oxidation resistance, and balance the alloying contents (Ni, Mn, Cr, Al, Mo) to suppress the ferritic phase and promote the austenitic matrix phase. Four steels (two ferritic + two austenitic) were designed and tested. The two Chi-phase strengthened ferritic steels exhibited excellent oxidation resistance and good creep-rupture strength at moderate temperatures, considering their ferritic matrix that usually results in lower creep resistance than austenitic steels. These steels showed brittleness and sample-to-sample variability in ductility. The low ductility might be due to the macro segregation during solidification or the significant grain growth during the solution heat treatments. We believe there is no inherent brittleness based on the chemistry of the steels. The creep-rupture performance of the steels is comparable to the 9Cr steels. Due to their ferritic matrix, the new Chi-phase strengthened ferritic steels may not be suited for the 760 °C AUSC applications, but they are very good candidates for intermediate temperature applications due to their outstanding oxidation resistance and high strength. Further study is required to find the source of low and highly variable ductility. We believe the compositions of the Chi-phase strengthened steels are not inherently brittle. The Chi-phase strengthened ferritic steels may also be excellent candidates for intermediate-temperature and room-temperature cast stainless steels, thus we highly recommend further investigations. The two Mn-containing austenitic steels based on the Laves phase showed good ductility, excellent oxidation resistance (slightly inferior to the two ferritic steels) at high temperatures and moderate creep strength. The creep-strength of the two austenitic steels based on the Larson-Miller parameters is higher than that of the traditional 316 stainless steels, but lower than the alumina-forming alloys (AFAs) developed at Oak Ridge National Laboratories. We do not recommend high priority in further studying these compositions unless higher Cr alloys are required for hot-corrosion resistance.« less

Chromium nanoparticle exhibits higher absorption efficiency than chromium picolinate and chromium chloride in Caco-2 cell monolayers.

PubMed

Zha, L-Y; Xu, Z-R; Wang, M-Q; Gu, L-Y

2008-04-01

This study was conducted to determine whether chromium nanoparticle (CrNano) exhibited higher absorption efficiency and possessed unique absorption mechanism in comparison to chromium picolinate (CrPic) and chromium chloride (CrCl(3)), as was postulated by previous reports. Twenty-one-day-old Caco-2 cell monolayers grown on semipermeable membranes in Snapwell tissue culture bichambers were incubated with CrNano, CrPic or CrCl(3) to examine their transport and uptake respectively. In the concentration range of 0.2-20 micromol/l, transport of CrNano, CrPic and CrCl(3) across Caco-2 monolayers both in apical-to-basolateral and basolateral-to-apical direction was concentration-, and time-dependent, and temperature independent. The apparent permeability coefficient (P(app)) of CrNano was between 5.89 and 7.92 x 10(-6) cm/s and that of CrPic and CrCl(3) was between 3.52 and 5.31 x 10(-6) cm/s and between 0.97 and 1.37 x 10(-6) cm/s respectively. Uptake of CrNano, CrPic and CrCl(3) by both apical and basolateral membranes was concentration- and time-dependent. Uptake of CrNano by apical membrane was significantly (p < 0.05) decreased when the incubation temperature was reduced from 37 degrees C to 4 degrees C. The transport efficiency of CrNano, CrPic and CrCl(3) after incubation for 120 min at 37 degrees C was 15.83% +/- 0.76%, 9.08% +/- 0.25% and 2.11% +/- 0.53% respectively. The uptake efficiency of CrNano, CrPic and CrCl(3) was 10.08% +/- 0.76%, 4.73% +/- 0.60% and 0.88% +/- 0.08% respectively. It was concluded that the epithelial transport of CrNano, CrPic and CrCl(3) across the Caco-2 cell monolayers was mainly via passive transport pathways. In addition, CrNano exhibited considerably higher absorption efficiency than both CrPic and CrCl(3) in Caco-2 cell monolayers.

Heavy metal distribution in sediment profiles of Tuul River, Mongolia

NASA Astrophysics Data System (ADS)

Soyol-Erdene, T. O.; Lin, S.; Tuuguu, E.; Daichaa, D.; Ulziibat, B.; Enkh-Amgalan, T.; Hsieh, I. C.

2016-12-01

The distribution, enrichment, and accumulation of heavy metals in the sediments of Tuul River, Mongolia were investigated. Sediment core samples with depths of 4.0-49 cm from thirteen locations along the Tuul River were collected in the period from Sept. 2013 to Aug. 2014 and characterized for metal contents (e.g., Al, Fe, Cu, Zn, Pb, Ni, Cd, Hg and Cr), water content, and grain size. Results showed that metal average concentrations in the sample cores varied from 0.02 mg kg-1 for Hg (0.01 - 0.03 mg kg-1) to 481 mg kg-1 for Mn (277 - 623 mg kg-1). Metal concentrations at the downstream of the capital city were higher than those at other locations. All heavy metals studied, had average enrichment factors less than 3.0, but some sites had relatively higher values of enrichment factors up to 18 for Cu, 4.1 for Hg, 5.9 for Zn, and 25 for Cr, especially at middle depth ( 8-12 cm) of the cores. Importantly, severe pollution of mercury (Hg) was found at the downstream of the capital city which requires immediate remediation before this metal propagates into the food chain. Metal concentrations correlated to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the nearby cities. Results of this work would help to develop strategy to remediate of Tuul river sediment and to reduce the exposure of inhabitants to toxic substances.

Spatial distribution and risk assessment of heavy metals and As pollution in the sediments of a shallow lake.

PubMed

Deng, Jiancai; Wang, Yuansheng; Liu, Xin; Hu, Weiping; Zhu, Jinge; Zhu, Lin

2016-05-01

The concentrations and spatial distributions of eight heavy metals in surface sediments and sediment core samples from a shallow lake in China were investigated to evaluate the extent of the contamination and potential ecological risks. The results showed that the heavy metal concentrations were higher in the northern and southwestern lake zones than those in the other lake zones, with lower levels of As, Hg, Zn, Cu, Pb, Cr, and Ni primarily observed in the central and eastern lake regions and Cd primarily confined to areas surrounding the lake. The concentrations of the eight heavy metals in the sediment profiles tended to decrease with increasing sediment depth. The contents of Ni, Cu, Zn, Pb, and Cd in the surface sediment were approximately 1.23-18.41-fold higher than their background values (BVs), whereas the contents of Cr, As, and Hg were nearly identical to their BVs. The calculated pollution load index (PLI) suggested that the surface sediments of this lake were heavily polluted by these heavy metals and indicated that Cd was a predominant contamination factor. The comprehensive potential ecological risk index (PERI) in the surface sediments ranged from 99.2 to 2882.1, with an average of 606.1. Cd contributed 78.7 % to the PERI, and Hg contributed 8.4 %. Multivariate statistical analyses revealed that the surface sediment pollution with heavy metals mainly originated from industrial wastewater discharged by rivers located in the western and northwestern portion of the lake.

Comparison of Selected Metals Content in Cambodian Striped Snakehead Fish (Channa striata) Using Solar Drying System and Open Sun Drying

PubMed Central

Abu Bakar, Nur Faizah; Fudholi, Ahmad; Ruslan, Mohd Hafidz; Saroeun, Im

2015-01-01

The content of 12 elements in Cambodian dried striped snakehead fish was determined using inductively coupled plasma mass spectrometry. The present study compares the level of the trace toxic metals and nutritional trace elements in the fish processed using solar drying system (SDS) and open sun drying (OSD). The skin of SDS fish has lower level of As, Pb, and Cd compared to the OSD sample. As such, the flesh of the fish accumulated higher amount of toxic metals during OSD compared to SDS. However, arsenic was detected in both samples within the safe limit. The nutritional elements (Fe, Mn, Mg, Se, Mo, Cu, Ni, and Cr) were higher in the skin sample SDS fish compared to OSD fish. These beneficial metals were not accumulated in the flesh sample SDS fish demonstrating lower level compared to drying under conventional system. The reddish coloration of the SDS fish was due to the presence of high Cu content in both the skin and flesh samples which possibly account for no mold formation 5 days after packaging. As conclusion, drying of Cambodian C. striata using solar-assisted system has proven higher content of the nutritious elements compared to using the conventional system despite only slight difference in the toxic metals level between the two systems. PMID:25688274

[Speciation Distribution and Risk Assessment of Heavy Metals in Typical Material Roof Dusts].

PubMed

Li, Dun-zhu; Guan, Yun-tao; Liu, An; Li, Si-yuan

2015-09-01

With the modified BCR sequential extraction procedure, the chemical speciation and risk for 10 heavy metals (Ba, Co, Cr, Cu, Mn, Ni, Pb, Sb, Sr and Zn) in roof dusts were investigated. The subjects of this study were collected from four typical material paved roofs (i. e., ceramic tile, concrete, metal and asphalt) in southeast China. The results indicated that the average contents of heavy metals in roof dust significantly exceeded road dust. The analysis of chemical fraction showed that the acid soluble/exchangeable fraction of Zn was much higher than other elements, the existence of Pb and Cu was mainly in oxidization fraction, while other heavy metals dominated by the residual fraction. The mobility sequence percentages for all roof dust samples decreased in the order of Pb > Zn > Cu >Mn > Co >Sr > Sb > Ni > Ba > Cr, and it should be noted that Pb, Zn, Cu, Mn and Co all have more than 50% proportion in mobility sequence. Based on environmental risk assessment, the highest values of contamination factors (Cf) and risk assessment code (RAC) consistently was observed in Zn, which indicated that Zn had relatively high ecological risk. Health risk assessment showed that the non-carcinogenic hazard indexes (HI) of heavy metals decreased in the order of Pb > Cr > Sb > Zn > Mn > Cu > Ba > Ni > Co > Sr, the HI of heavy metals for adults were lower than safe value while the HI of Pb for children was higher than safe value, suggesting that they will not harm the adult's health except Pb for children. The carcinogenic risk for Cr, Co and Ni were all below the threshold values, which indicated that there was no carcinogenic risk.

Influence of Temperature on Fatigue-Induced Martensitic Phase Transformation in a Metastable CrMnNi-Steel

NASA Astrophysics Data System (ADS)

Biermann, Horst; Glage, Alexander; Droste, Matthias

2016-01-01

Metastable austenitic steels can exhibit a fatigue-induced martensitic phase transformation during cyclic loading. It is generally agreed that a certain strain amplitude and a threshold of the cumulated plastic strain must be exceeded to trigger martensitic phase transformation under cyclic loading. With respect to monotonic loading, the martensitic phase transformation takes place up to a critical temperature—the so-called M d temperature. The goal of the present investigation is to determine an M d,c temperature which would be the highest temperature at which a fatigue-induced martensitic phase transformation can take place. For this purpose, fatigue tests controlled by the total strain were performed at different temperatures. The material investigated was a high-alloy metastable austenitic steel X3CrMnNi16.7.7 (16.3Cr-7.2Mn-6.6Ni-0.03C-0.09N-1.0Si) produced using the hot pressing technique. The temperatures were set in the range of 283 K (10 °C) ≤ T ≤ 473 K (200 °C). Depending on the temperature and strain amplitude, the onset of the martensitic phase transformation shifted to different values of the cumulated plastic strain, or was inhibited completely. Moreover, it is known that metastable austenitic CrMnNi steels with higher nickel contents can exhibit the deformation-induced twinning effect. Thus, at higher temperatures and strain amplitudes, a transition from the deformation-induced martensitic transformation to deformation-induced twinning takes place. The fatigue-induced martensitic phase transformation was monitored during cyclic loading using a ferrite sensor. The microstructure after the fatigue tests was examined using the back-scattered electrons, the electron channeling contrast imaging and the electron backscatter diffraction techniques to study the temperature-dependent dislocation structures and phase transformations.

Evaluation of Levels, Sources and Health Hazards of Road-Dust Associated Toxic Metals in Jalalabad and Kabul Cities, Afghanistan.

PubMed

Jadoon, Waqar Azeem; Khpalwak, Wahdatullah; Chidya, Russel Chrispine Garven; Abdel-Dayem, Sherif Mohamed Mohamed Ali; Takeda, Kazuhiko; Makhdoom, Masood Arshad; Sakugawa, Hiroshi

2018-01-01

This study was designed to investigate selected road-dust associated heavy metals, their relations with natural and anthropogenic sources, and potential human and environmental health risks. For this purpose, 42 and 36 road-dusts samples were collected from Jalalabad and Kabul cities (Afghanistan), respectively. The following elements were found in descending concentrations: Mn, Zn, Pb, Ni, Cu, Cr, Co, and Cd in Jalalabad; and Mn, Zn, Ni, Cu, Cr, Pb, Co, and Cd in Kabul. Except for Ni, all the elemental contents were less than the Canadian permissible limits in residential/parkland soils. Principle Component Analysis and enrichment of Cd, Cu, Ni, Pb, and Zn pointed to anthropogenic sources, whereas Co, Cr, and Mn indicated crustal inputs. Broadly, Cd monomial risk index ([Formula: see text]) was considerable; however, one site each in both cities showed high risk ([Formula: see text] ≥ 350). The potential ecological risk (RI) is mostly low; however, at some sites, the risk was considerable. Ingestion appeared to be the main exposure route (99%) for heavy metals and contributed > 90% to noncancerous (all residents), as well as 92% (children) and 75-89% (adults) cancerous risks. The noncancerous risks of all metals and their integrated risks for all residents were within acceptable levels. Moreover, potential cancer risks in children from Ni and Cr were slightly higher than the US-EPA safe levels but were within acceptable levels for adults. This study found higher risks to children and therefore recommends proper management and ways to control metals pollution load in these areas to decrease human health and RIs.

Microstructures and Surface Stabilities of {Ni-0.4C-6Ta- xCr, 0 ≤ x ≤ 50 Wt Pct} Cast Alloys at High Temperature

NASA Astrophysics Data System (ADS)

Berthod, Patrice

2018-06-01

Nickel-based cast alloys rich in chromium and reinforced by TaC carbides are potentially very interesting alloys for applications at elevated temperatures. Unfortunately, unlike cobalt-chromium and iron-chromium alloys, it is difficult to obtain exclusively TaC as primary carbides in Ni-Cr alloys. In alloys containing 30 wt pct Cr tantalum, carbides coexist with chromium carbides. The latter tend to weaken the alloy at elevated temperatures because they become rapidly spherical and then quickly lose their reinforcing effect. In this work, we attempted to stabilize TaC as a single carbide phase by testing different chromium contents in the [0, 50 wt pct] range. Six alloys containing 0.4C and 6Ta, weight contents corresponding to equivalent molar contents, were elaborated by foundry, and their as-cast microstructures were characterized. Samples of all alloys were exposed to 1127 °C and 1237 °C for 24 hours to characterize their stabilized microstructures. The surface fractions of chromium carbides and tantalum carbides were measured by image analysis, and their evolutions vs the chromium content were studied. For the chosen C and Ta contents, it appears that obtaining TaC only is possible by decreasing the chromium content to 10 wt pct. At the same time, TaC fractions are unfortunately too low because a large portion of tantalum integrates into the solid solution in the matrix. A second consequence is a critical decrease in oxidation resistance. Other possible methods to stabilize TaC as a single carbide are evocated, such as the simultaneous increase in Ta and decrease in chromium from 30 wt pct Cr.

Influence of Ni-Cr substitution on the magnetic and electric properties of magnesium ferrite nanomaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com; Ahmad, Zahoor; Meydan, Turgut

2012-02-15

Graphical abstract: Variation of saturation magnetization (M{sub S}) and magnetocrystalline anisotropy coefficient (K{sub 1}) with Ni-Cr content for Mg{sub 1-x}Ni{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4} (x = 0.0-0.5). Highlights: Black-Right-Pointing-Pointer Mg{sub 1-x}Ni{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4} are synthesized by novel PEG assisted microemulsion method. Black-Right-Pointing-Pointer High field regime of M-H loops are modeled using Law of Approach to saturation. Black-Right-Pointing-Pointer A considerable increase in the value of M{sub S} from 148 kA/m to 206 kA/m is achieved Black-Right-Pointing-Pointer {rho}{sup RT} enhanced to the order of 10{sup 9} {Omega}cm at potential operational range around 300 K. -- Abstract: The effect of variationmore » of composition on the structural, morphological, magnetic and electric properties of Mg{sub 1-x}Ni{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4} (x = 0.0-0.5) nanocrystallites is presented. The samples were prepared by novel polyethylene glycol (PEG) assisted microemulsion method with average crystallite size of 15-47 nm. The microstructure, chemical, and phase analyses of the samples were studied by the scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray fluorescence (ED-XRF), and X-ray diffraction (XRD). Compositional variation greatly affected the magnetic and structural properties. The high-field regimes of the magnetic loops are modelled using the Law of Approach (LOA) to saturation in order to extract information about their anisotropy and the saturation magnetization. Thermal demagnetization measurements are carried out using VSM and significant enhancement of the Curie temperature from 681 K to 832 K has been achieved by substitution of different contents of Ni-Cr. The dc-electrical resistivity ({rho}{sup RT}) at potential operational range around 300 K is increased from 7.5 Multiplication-Sign 10{sup 8} to 4.85 Multiplication-Sign 10{sup 9} {Omega}cm with the increase in Ni-Cr contents. Moreover, the results of the present study provide sufficient evidence to show that the electric and magnetic properties of Mg-ferrite have been improved significantly by substituting low contents of Ni-Cr.« less

Fireside Corrosion Behaviors of Super304H and HR3C in Coal Ash/Gas Environment with Different SO2 Contents at 650 °C

NASA Astrophysics Data System (ADS)

Lu, Jintao; Yang, Zhen; Li, Yan; Huang, Jinyang; Zhou, Yongli; Zhao, Xinbao; Yuan, Yong

2018-05-01

The corrosion behaviors of Super304H and HR3C used for USC boiler applications were investigated in simulated coal ash/gas environments with 0.1 and 1.5% of SO2 at 650 °C for 500 h. The results indicated that the increase in SO2 accelerated the corrosion rate and the spalling tendency of the corrosion layer in both tested alloys. Fe2O3, Cr2O3 and FeCr2O4 main peaks were revealed by XRD on Super304H, but on HR3C only the Cr2O3 peak showed a high intensity. The SO2 content did not affect the corrosion product composition of any of the alloys, but accelerated the inner sulfidation and the spallation on Super304H. No obvious internal sulfidation was observed on HR3C in either SO2 content. Based on the experimental results, the alloy corrosion mechanism and the influence of sulfur content on the corrosion process were discussed.

Concept of Aided Phytostabilization of Contaminated Soils in Postindustrial Areas

PubMed Central

Koda, Eugeniusz; Bilgin, Ayla; Vaverková, Mgdalena D.

2017-01-01

The experiment was carried out in order to evaluate the effects of trace element immobilizing soil amendments, i.e., chalcedonite, dolomite, halloysite, and diatomite on the chemical characteristics of soil contaminated with Cr and the uptake of metals by plants. The study utilized analysis of variance (ANOVA), principal component analysis (PCA) and Factor Analysis (FA). The content of trace elements in plants, pseudo-total and extracted by 0.01 M CaCl2, were determined using the method of spectrophotometry. All of the investigated element contents in the tested parts of Indian mustard (Brassica juncea L.) differed significantly in the case of applying amendments to the soil, as well as Cr contamination. The greatest average above-ground biomass was observed when halloysite and dolomite were amended to the soil. Halloysite caused significant increases of Cr concentrations in the roots. The obtained values of bioconcentration and translocation factors observed for halloysite treatment indicate the effectiveness of using Indian mustard in phytostabilization techniques. The addition of diatomite significantly increased soil pH. Halloysite and chalcedonite were shown to be the most effective and decreased the average Cr, Cu and Zn contents in soil. PMID:29295511

Essential and toxic elements in infant foods from Spain, UK, China and USA.

PubMed

Carbonell-Barrachina, Ángel A; Ramírez-Gandolfo, Amanda; Wu, Xiangchun; Norton, Gareth J; Burló, Francisco; Deacon, Claire; Meharg, Andrew A

2012-09-01

Spanish gluten-free rice, cereals with gluten, and pureed baby foods were analysed for essential macro-elements (Ca and Na), essential trace elements (Fe, Cu, Zn, Mn, Se, Cr, Co and Ni) and non-essential trace elements (As, Pb, Cd and Hg) using ICP-MS and AAS. Baby cereals were an excellent source of most of the essential elements (Ca, Fe, Cu, Mn and Zn). Sodium content was high in pureed foods to improve their flavour; fish products were also rich in Se. USA pure baby rice samples had the highest contents of all studied essential elements, showing a different nutrient pattern compared to those of other countries. Mineral fortification was not always properly stated in the labelling of infant foods. Complementary infant foods may also contain significant amounts of contaminants. The contents of Hg and Cd were low enough to guarantee the safety of these infant foods. However, it will be necessary to identify the source and reduce the levels of Pb, Cr and As in Spanish foods. Pure baby rice samples contained too much: Pb in Spain; As in UK; As, Cr and Ni in USA; and Cr and Cd in China.

Concept of Aided Phytostabilization of Contaminated Soils in Postindustrial Areas.

PubMed

Radziemska, Maja; Koda, Eugeniusz; Bilgin, Ayla; Vaverková, Mgdalena D

2017-12-23

The experiment was carried out in order to evaluate the effects of trace element immobilizing soil amendments, i.e., chalcedonite, dolomite, halloysite, and diatomite on the chemical characteristics of soil contaminated with Cr and the uptake of metals by plants. The study utilized analysis of variance (ANOVA), principal component analysis (PCA) and Factor Analysis (FA). The content of trace elements in plants, pseudo-total and extracted by 0.01 M CaCl₂, were determined using the method of spectrophotometry. All of the investigated element contents in the tested parts of Indian mustard ( Brassica juncea L.) differed significantly in the case of applying amendments to the soil, as well as Cr contamination. The greatest average above-ground biomass was observed when halloysite and dolomite were amended to the soil. Halloysite caused significant increases of Cr concentrations in the roots. The obtained values of bioconcentration and translocation factors observed for halloysite treatment indicate the effectiveness of using Indian mustard in phytostabilization techniques. The addition of diatomite significantly increased soil pH. Halloysite and chalcedonite were shown to be the most effective and decreased the average Cr, Cu and Zn contents in soil.

Cyclic Oxidation Behavior and Durability of ODS-FeCrAl Alloys in H2O and CO2 rich environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dryepondt, Sebastien N; Pint, Bruce A

Cyclic oxidation testing was conducted at 1200 C in O2, dry air and in atmospheres rich in H2O and/or CO2 to simulate combustion environments. The oxidation rates were significantly higher in air + 10%H2O and a mixture of O2-buffered 50%H2O-50%CO2, leading to shorter times to breakaway oxidation. Curve fitting using the COSP cyclic oxidation program confirmed that the presence of H2O results in an increase of the alumina spallation rate. The use of specimen mass gain modeling associated with the characterization of pre-oxidized specimens and in particular the determination of the remaining Al content after exposure, will allow to accuratelymore » estimate the durability of oxide dispersion-strengthened (ODS) FeCrAl alloys in combustion environments.« less

Application of a three-feature dispersed-barrier hardening model to neutron-irradiated Fe-Cr model alloys

NASA Astrophysics Data System (ADS)

Bergner, F.; Pareige, C.; Hernández-Mayoral, M.; Malerba, L.; Heintze, C.

2014-05-01

An attempt is made to quantify the contributions of different types of defect-solute clusters to the total irradiation-induced yield stress increase in neutron-irradiated (300 °C, 0.6 dpa), industrial-purity Fe-Cr model alloys (target Cr contents of 2.5, 5, 9 and 12 at.% Cr). Former work based on the application of transmission electron microscopy, atom probe tomography, and small-angle neutron scattering revealed the formation of dislocation loops, NiSiPCr-enriched clusters and α‧-phase particles, which act as obstacles to dislocation glide. The values of the dimensionless obstacle strength are estimated in the framework of a three-feature dispersed-barrier hardening model. Special attention is paid to the effect of measuring errors, experimental details and model details on the estimates. The three families of obstacles and the hardening model are well capable of reproducing the observed yield stress increase as a function of Cr content, suggesting that the nanostructural features identified experimentally are the main, if not the only, causes of irradiation hardening in these model alloys.

Quantification of total and hexavalent chromium in lager beers: variability between styles and estimation of daily intake of chromium from beer.

PubMed

Vieira, Elsa; Soares, M Elisa; Kozior, Marta; Krejpcio, Zbigniew; Ferreira, Isabel M P L V O; Bastos, M Lourdes

2014-09-17

A survey of the presence of total and hexavalent chromium in lager beers was conducted to understand the variability between different styles of lager beer packaged in glass or cans and to estimate daily intake of total Cr and hexavalent chromium from beer. Graphite-furnace atomic absorption spectroscopy using validated methodologies was applied. Selective extraction of hexavalent chromium was performed using a Chromabond NH2/500 mg column and elution with nitric acid. The detection limits were 0.26 and 0.68 μg L(-1) for total Cr and Cr(VI), respectively. The mean content of total Cr ranged between 1.13 μg L(-1) in canned pale lager and 4.32 μg L(-1) in low-alcohol beers, whereas the mean content of Cr(VI) was <2.51 μg L(-1). Considering an intake of 500 mL of beer, beer consumption can contribute approximately 2.28-8.64 and 1.6-6.17% of the recommended daily intake of chromium for women and men, respectively.

Inputs and spatial distribution patterns of Cr in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Miao, Zhenqing; Huang, Xinmin; Wei, Linzhen; Feng, Ming

2018-03-01

Cr pollution in marine bays has been one of the critical environmental issues, and understanding the input and spatial distribution patterns is essential to pollution control. In according to the source strengths of the major pollution sources, the input patterns of pollutants to marine bay include slight, moderate and heavy, and the spatial distribution are corresponding to three block models respectively. This paper analyzed input patterns and distributions of Cr in Jiaozhou Bay, eastern China based on investigation on Cr in surface waters during 1979-1983. Results showed that the input strengths of Cr in Jiaozhou Bay could be classified as moderate input and slight input, and the input strengths were 32.32-112.30 μg L-1 and 4.17-19.76 μg L-1, respectively. The input patterns of Cr included two patterns of moderate input and slight input, and the horizontal distributions could be defined by means of Block Model 2 and Block Model 3, respectively. In case of moderate input pattern via overland runoff, Cr contents were decreasing from the estuaries to the bay mouth, and the distribution pattern was parallel. In case of moderate input pattern via marine current, Cr contents were decreasing from the bay mouth to the bay, and the distribution pattern was parallel to circular. The Block Models were able to reveal the transferring process of various pollutants, and were helpful to understand the distributions of pollutants in marine bay.

Translation, Cross-cultural Adaptation and Psychometric Validation of the Korean-Language Cardiac Rehabilitation Barriers Scale (CRBS-K)

PubMed Central

2017-01-01

Objective To perform a translation and cross-cultural adaptation of the Cardiac Rehabilitation Barriers Scale (CRBS) for use in Korea, followed by psychometric validation. The CRBS was developed to assess patients' perception of the degree to which patient, provider and health system-level barriers affect their cardiac rehabilitation (CR) participation. Methods The CRBS consists of 21 items (barriers to adherence) rated on a 5-point Likert scale. The first phase was to translate and cross-culturally adapt the CRBS to the Korean language. After back-translation, both versions were reviewed by a committee. The face validity was assessed in a sample of Korean patients (n=53) with history of acute myocardial infarction that did not participate in CR through semi-structured interviews. The second phase was to assess the construct and criterion validity of the Korean translation as well as internal reliability, through administration of the translated version in 104 patients, principle component analysis with varimax rotation and cross-referencing against CR use, respectively. Results The length, readability, and clarity of the questionnaire were rated well, demonstrating face validity. Analysis revealed a six-factor solution, demonstrating construct validity. Cronbach's alpha was greater than 0.65. Barriers rated highest included not knowing about CR and not being contacted by a program. The mean CRBS score was significantly higher among non-attendees (2.71±0.26) than CR attendees (2.51±0.18) (p<0.01). Conclusion The Korean version of CRBS has demonstrated face, content and criterion validity, suggesting it may be useful for assessing barriers to CR utilization in Korea. PMID:29201826

Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

NASA Astrophysics Data System (ADS)

Greunz, Theresia; Duchaczek, Hubert; Sagl, Raffaela; Duchoslav, Jiri; Steinberger, Roland; Strauß, Bernhard; Stifter, David

2017-02-01

Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1-3 μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (<10 nm) and that the lowest commonly achievable lateral resolution is a number of times higher than the coating thickness (∼2 μm), a bulk analysis was achieved with XPS line scans on extended wedge-shaped tapers through the coating. For that purpose a special sample preparation step performed on an ultra-microtome was required prior to analysis. Since a temperature increase leads to a reduction of Cr(VI) we extend our method on samples, which were subjected to different curing temperatures. We show that our proposed approach now allows to determine the elemental and Cr(VI) concentration and distribution inside the coating.

Fenugreek increases insulin-stimulated creatine content in L6C11 muscle myotubes.

PubMed

Tomcik, Kristyen A; Smiles, William J; Camera, Donny M; Hügel, Helmut M; Hawley, John A; Watts, Rani

2017-04-01

Creatine uptake by muscle cells is increased in the presence of insulin. Accordingly, compounds with insulin-like actions may also augment creatine uptake. The aim of this study was to investigate whether Trigonella foenum-graecum (fenugreek), an insulin mimetic, increases total intracellular creatine levels in vitro. Total cellular creatine content was measured fluorometrically in L6C11 muscle myotubes treated for 1, 4, and 24 h with 0.5 mM creatine (CR), CR and 20 μg/mL fenugreek seed extract (CR + FEN), CR and 100 nM insulin (CR + INS), and CR + INS + FEN (n = 6 per treatment group). Alterations in the expression of the sodium- and chloride-dependent creatine transporter, SLC6A8, and key signaling proteins in the PI3-K/Akt pathway were determined. Compared to control (CON), CR + INS + FEN increased total creatine content after 4 h (P < 0.05), whereas all conditions increased SLC6A8 protein expression above CON at this time (P < 0.05). Changes in insulin signaling were demonstrated via increases in Akt Thr308 phosphorylation, with CR + INS > CON and CR at 1 h (P < 0.05) and with CR + INS + FEN > CON, CR, and CR + INS at 4 h (P < 0.05). In contrast, no changes in PKCζ/λ or GLUT4 phosphorylation were detected. Fenugreek, when combined with insulin, modulates creatine content via a mechanism which is independent of the activity of SLC6A8, suggesting that an alternative mechanism is responsible for the regulation and facilitation of insulin-mediated creatine uptake in skeletal muscle cells.

Spatial Distribution, Chemical Fraction and Fuzzy Comprehensive Risk Assessment of Heavy Metals in Surface Sediments from the Honghu Lake, China

PubMed Central

Xiao, Minsi; Zhang, Jingdong; Liu, Chaoyang; Qiu, Zhenzhen; Cai, Ying

2018-01-01

Spatial concentrations and chemical fractions of heavy metals (Cr, Cu, Pb, Zn and Cd) in 16 sampling sites from the Honghu Lake were investigated using an atomic absorption spectrophotometer and optimized BCR (the European Community Bureau of Reference) three-stage extraction procedure. Compared with the corresponding probable effect levels (PELs), adverse biological effects of the studied five sediment metals decreased in the sequence of Cr > Cu > Zn > Pb > Cd. Geo-accumulation index (Igeo) values for Cr, Cu, Pb and Zn in each sampling site were at un-contamination level, while the values for Cd varied from un-contamination level to moderate contamination level. Spatially, the enrichment degree of Cd in lower part of the South Lake, the west part of the North Lake and the outlet were higher than the other parts of Honghu Lake. For metal chemical fractions, the proportions of the acid-extractable fraction of five metal contents were in the descending order: Cd, Cu, Zn, Pb and Cr. Cd had the highest bioaccessibility. Being the above indexes focused always on heavy metals’ total content or chemical fraction in deterministic assessment system, which may confuse decision makers, the fuzzy comprehensive risk assessment method was established based on PEI (Potential ecological risk index), RAC (Risk assessment code) and fuzzy theory. Average comprehensive risks of heavy metals in sediments revealed the following orders: Cd (considerable risk) > Cu (moderate risk) > Zn (low risk) > Pb > Cr. Thus, Cd and Cu were determined as the pollutants of most concern. The central part of South Honghu Lake (S4, S5, S6, S9, S12 and S14), east part of the North Honghu Lake (S1) and outlet of outlet of the Honghu Lake (S10) were recommended as the priority control areas. Specifically, it is necessary to pay more attention to S1, S4, S5, S6, S9 and S16 when decision making for their calculated membership values (probabilities) of adjacent risk levels quite close. PMID:29373483

Remediation of Cr(VI)-Contaminated Soil Using the Acidified Hydrazine Hydrate.

PubMed

Ma, Yameng; Li, Fangfang; Jiang, Yuling; Yang, Weihua; Lv, Lv; Xue, Haotian; Wang, Yangyang

2016-09-01

Acidified hydrazine hydrate was used to remediate Cr(VI)-contaminated soil. The content of water-soluble Cr(VI) in contaminated soil was 4977.53 mg/kg. The optimal initial pH of hydrazine hydrate solution, soil to solution ratio and molar ratio of Cr(VI) to hydrazine hydrate for remediation of Cr(VI)-contaminated soil were 5.0, 3:1 and 1:3, respectively. Over 99.50 % of water-soluble Cr(VI) in the contaminated soil was reduced at the optimal condition within 30 min. The remediated soil can keep stable within 4 months. Meanwhile the total phosphorus increased from 0.47 to 4.29 g/kg, indicating that using of acidified hydrazine hydrate is an effective method to remediate Cr(VI)-contaminated soil.

Citric acid enhanced the antioxidant defense system and chromium uptake by Lemna minor L. grown in hydroponics under Cr stress.

PubMed

Sallah-Ud-Din, Rasham; Farid, Mujahid; Saeed, Rashid; Ali, Shafaqat; Rizwan, Muhammad; Tauqeer, Hafiz Muhammad; Bukhari, Syed Asad Hussain

2017-07-01

Phytoextraction is a cost-effective and eco-friendly technique for the removal of pollutants, mainly heavy metal(loids) especially from polluted water and metal-contaminated soils. The phytoextraction of heavy metals is, in general, limited due to the low availability of heavy metals in the growth medium. Organic chelators can help to improve the phytoextraction by increasing metal mobility and solubility in the growth medium. The present research was carried out to examine the possibility of citric acid (CA) in improving chromium (Cr) phytoextraction by Lemna minor (duckweed). For this purpose, healthy plants were collected from nearby marsh and grown in hydroponics under controlled conditions. Initial metal contents of both marsh water and plant were measured along with physico-chemical properties of the marsh water. Different concentrations of Cr and CA were applied in the hydroponics in different combinations after defined intervals. Continuous aeration was supplied and pH maintained at 6.5 ± 0.1. Results showed that increasing concentration of Cr significantly decreased the plant biomass, photosynthetic pigments, leaf area, and antioxidant enzyme activities (like catalase, ascorbate peroxidase, superoxide dismutase, peroxidase). Furthermore, Cr stress increased the Cr concentrations, electrolyte leakage, hydrogen peroxide, and malondialdehyde contents in plants. The addition of CA alleviated the Cr-induced toxicity in plants and further enhanced the Cr uptake and its accumulation in L. minor. The addition of CA enhanced the Cr concentration in L. minor by 6.10, 26.5, 20.5, and 20.2% at 0, 10, 100, and 200 μM Cr treatments, respectively, compared to the respective Cr treatments without CA. Overall, the results of the present study showed that CA addition may enhance the Cr accumulation and tolerance in L. minor by enhancing the plant growth and activities of antioxidant enzymes.

Electrodepositing behaviors and properties of nano Fe-Ni-Cr/SiC composite coatings from trivalent chromium baths containing compound carboxylate-urea system.

PubMed

He, Xinkuai; Hou, Bailong; Cai, Youxing; Li, Chen; Jiang, Yumei; Wu, Luye

2013-06-01

The nano Fe-Ni-Cr/SiC composite coatings were prepared using pulse electrodeposition method from trivalent chromium baths containing compound carboxylate-urea system and nano SiC in ultrasonic field. The effects of the carboxylate-urea system on the nano Fe-Ni-Cr/SiC composite coatings have been investigated. These results indicated that the SiC and Cr contents and the thickness of the Fe-Ni-Cr/SiC composite coatings could be obviously improved by the compound carboxylate-urea system. The steady-state polarization curves showed that the hydrogen evolution reaction (HER) could be significantly inhibited by the compound carboxylate-urea system, which was benefit to increase the SiC and Cr contents and the thickness of the composite coatings. The cyclic voltammetry (CV) curves showed that the cathodic polarization of the matrix metal ions could be increased in the bath containing the compound carboxylate-urea system. Thus, a compact Fe-Ni-Cr/SiC composite coating could be obtained using this technique. The surface morphology of the Fe-Ni-Cr/SiC composite coatings checked with the scanning electron micrographs (SEM) showed that the surface smoothness could be also improved and the microcracks and pinholes could be decreased due to the presence of the compound carboxylate-urea system. The phase composition of the as-posited coating was measured by the X-ray diffraction (XRD). XRD data showed that the as-posited coating was Fe-Ni-Cr/SiC composite coating. The chemical composition of the coating was investigated by energy dispersive spectrum (EDS) analysis. The result showed the functional Fe-Ni-Cr/SiC composite coatings with 4.1 wt.% SiC and 25.1 wt.% Cr, and 23.9 microm thickness were obtained in this study, which had best corrosion resistance according to the results of the typical potentiodynamic polarization curves of the Fe-Ni-Cr/SiC composite coatings.

Increase of olfactory threshold in plating factory workers exposed to chromium in Korea.

PubMed

Kitamura, Fumihiko; Yokoyama, Kazuhito; Araki, Shunichi; Nishikitani, Mariko; Choi, Jae-Wook; Yum, Youg-Tae; Park, Hee-Chan; Park, Sang-Hwoi; Sato, Hajime

2003-07-01

To disclose the effects of chromium (Cr) on olfactory function, olfactory threshold tests were conducted on 27 male plating workers (Cr workers) with signs and symptoms of olfactory irritation but without nasal septum perforation or ulcer and on 34 male control subjects in Korean plating factories. The Cr workers had been exposed to Cr fume for 0.9 to 18.2 (mean 7.9) years; their blood Cr concentrations (0.16-3.69, mean 1.29 microg/dl) were significantly higher than those of the 34 control subjects (0.04-1.95, mean 0.55 microg/dl). Scores on recognition thresholds among the Cr workers were significantly higher than those of the control subjects (p < 0.05) and related positively and significantly to the exposure periods of the 27 Cr workers (p < 0.05). Olfactory thresholds were not significantly different between the Cr workers with and without nasal signs or symptoms, except that the scores on the recognition threshold were significantly higher in those experiencing difficulty with smell (p < 0.05). It is suggested that olfactory threshold is affected by Cr without development of nasal septum perforation or ulceration.

Spectral Resolution and Coverage Impact on Advanced Sounder Information Content

NASA Technical Reports Server (NTRS)

Larar, Allen M.; Liu, Xu; Zhou, Daniel K.; Smith, William L.

2010-01-01

Advanced satellite sensors are tasked with improving global measurements of the Earth s atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such measurement improvements requires instrument system advancements. This presentation focuses on the impact of spectral resolution and coverage changes on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species variables obtainable from advanced atmospheric sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and Cross-track Infrared Sounder (CrIS) systems on the MetOp and NPP/NPOESS series of satellites. Key words: remote sensing, advanced sounders, information content, IASI, CrIS

Effect of feeding sorghum straw based complete rations with different roughage to concentrate ratio on dry matter intake, nutrient utilization, and nitrogen balance in Nellore ram lambs.

PubMed

Malisetty, Venkateswarlu; Yerradoddi, Ramana Reddy; Devanaboina, Nagalakshmi; Mallam, Mahender; Mitta, Pavani

2014-06-01

An experiment was conducted by feeding sorghum straw (Sorghum bicolor) based complete rations at roughage concentrate ratio 70:30 (CR-I), 60:40 (CR-II), 50:50 (CR-III), and 40:60 (CR-IV) for 180 days to find out suitable ratio of sorghum straw in the complete ration (mash form) on nutrient utilization and nitrogen balance in Nellore ram lambs. The DMI (g/day) increased significantly (P < 0.05) as level of concentrate increased in complete rations. No significant difference was found in digestibilities of proximate nutrients. However, CP digestibility was higher either significantly or nonsignificantly by 2.12, 5.50, and 9.36 %, respectively, in lambs fed with CR-II (P > 0.05), CR-III (P > 0.05), and CR-IV (P < 0.05) rations in comparison to lambs fed with CR-I ration. Furthermore, CP digestibility was higher by 7.09 and 3.66 % in lambs fed with CR-IV ration than those fed with CR-II (P < 0.05) and CR-III (P > 0.05) ration. The average CWC digestibility coefficients were comparable among four rations. The N intake (g/day) was significantly (P < 0.01) different and progressively increased by 31.46, 48.69, and 82.86 % in ram lambs fed with CR-II, CR-III, and CR-IV rations, respectively, in comparison to CR-I ration. The N balance (g/day) was higher either significantly or nonsignificantly by 34.46 (P > 0.05), 133.46 (P < 0.01), and 198.87 % (P < 0.01) with CR-II, CR-III, and CR-IV rations, respectively, in comparison to CR-I ration. Based on results, it is inferred that the level of sorghum straw in complete ration had no effect on digestibility of nutrients barring crude protein in Nellore ram lambs.

Intergranular stress corrosion cracking and selective internal oxidation of nickel-chromium-iron alloys in hydrogenated steam

NASA Astrophysics Data System (ADS)

Capell, Brent M.

2005-07-01

Selective internal oxidation (SIO) is a mechanism of grain boundary embrittlement through the formation of intergranular oxides of Cr2O3. SIO is proposed as a mechanism to explain intergranular stress corrosion cracking (IGSCC) of Ni-base alloys in pressurized water reactor environments. The purpose of this work is to investigate SIO through a series of experiments using controlled-purity alloys in a controlled, low-pressure steam environment in which the oxygen potential is varied. Five alloys; Ni-9Fe, Ni-5Cr, LCr (Ni-5Cr-9Fe), CD85 (Ni-16Cr-9Fe) and HCr (Ni-30Cr-9Fe), were used in corrosion coupon exposure tests and constant extension rate tensile (CERT) tests at 550°C and 400°C in an environment consisting of a controlled mixture of hydrogen, water vapor and argon. The hydrogen-to-water vapor partial pressure ratio (PPR) was varied between 0.001 and 0.9 to control the oxygen partial pressure. The Ni-9Fe, Ni-5Cr and LCr alloys formed a uniform Ni(OH)2 film at PPR values less than 0.09 while CD85 and HCr formed Cr2O 3 oxide films over the entire PPR range. Corrosion coupon results also show the formation of highly localized oxide particles at grain boundaries. Focused ion beam analysis revealed that intergranular oxides were observed at significant depths (>150 nm) down grain boundaries and the oxide morphology depended on the alloy composition and PPR value. Diffusion of oxygen along the grain boundary accounted for the growth of intergranular oxides. CERT test results showed that intergranular cracking was caused by creep-induced microvoid coalescence only at 550°C and did not depend on PPR. At 400°C, the cracking behavior depended on the PPR and resulted in a mixture of creep-induced microvoid coalescence and brittle intergranular failure. The cracked boundary fraction was higher at a PPR value where a Ni(OH)2 surface film formed. Alloy composition influenced cracking and the cracked boundary fraction decreased as the alloy chromium content increased. The compositions of oxides at intergranular crack tips were similar to intergranular oxides in corrosion coupons and demonstrated a link between intergranular oxide formation and intergranular cracking. The observation of intergranular oxides as well as the influence of alloy content on IG cracking was found to support SIO as a mechanism for IGSCC.

Evaluation of metal content in perch of the Ob River basin

NASA Astrophysics Data System (ADS)

Osipova, N. A.; Stepanova, K. D.; Matveenko, I. A.

2015-11-01

The geochemical features of river perch in the River Ob basin have been studied (the upper and middle reaches of the Ob River and the lower reach of the Tom River). The contents of Ag, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, W, Zn, Hg in perch's soft tissue are defined by the methods of ICP AES and stripping voltammetry, that of mercury in bones - by the atomic absorption method using mercury analyzer PA-915+. The distribution series of metal absolute concentrations in perch's soft tissue from the Ob River basin are plotted: Fe > Zn > Cu > Mn, typical for uncontaminated or slightly metal contaminated water bodies. In soft tissue of the studied samples the metal content does not exceed the permissible values. The mercury content in bones of studied samples is in the range 0,036-0,556 mg/kg. The mercury concentration is higher in bones in comparison with soft tissue in all samples.

Blackberry wines mineral and heavy metal content determination after dry ashing: multivariate data analysis as a tool for fruit wine quality control.

PubMed

Amidžić Klarić, Daniela; Klarić, Ilija; Mornar, Ana; Velić, Darko; Velić, Natalija

2015-08-01

This study brings out the data on the content of 21 mineral and heavy metal in 15 blackberry wines made of conventionally and organically grown blackberries. The objective of this study was to classify the blackberry wine samples based on their mineral composition and the applied cultivation method of the starting raw material by using chemometric analysis. The metal content of Croatian blackberry wine samples was determined by AAS after dry ashing. The comparison between an organic and conventional group of investigated blackberry wines showed statistically significant difference in concentrations of Si and Li, where the organic group contained higher concentrations of these compounds. According to multivariate data analysis, the model based on the original metal content data set finally included seven original variables (K, Fe, Mn, Cu, Ba, Cd and Cr) and gave a satisfactory separation of two applied cultivation methods of the starting raw material.

Determination of the Cryolite Ratio of KF-NaF-AlF3 Electrolyte by Conductivity Method

NASA Astrophysics Data System (ADS)

Yan, Hengwei; Yang, Jianhong; Liu, Zhanwei; Wang, Chengzhi; Ma, Wenhui

2018-05-01

The cryolite ratio (CR) is an important parameter for the electrolyte in aluminum reduction cells. The measurement method for the CR of the KF-NaF-AlF3 system acid (CR < 3) electrolyte by means of electrical conductivity was initially developed, and the formula for calculating the CR was deduced. This method has the advantages of simple operation and high precision. In addition, the relative standard deviations (RSD) of the measurement are < 1.2 pct, and the analysis error of the NaF or KF content has little effect on the determination of the CR.

Non-invasive grading of astrocytic tumours from the relative contents of myo-inositol and glycine measured by in vivo MRS.

PubMed

Candiota, A P; Majós, C; Julià-Sapé, M; Cabañas, M; Acebes, J J; Moreno-Torres, A; Griffiths, J R; Arús, C

2011-01-01

MRI and MRS are established methodologies for evaluating intracranial lesions. One MR spectral feature suggested for in vivo grading of astrocytic tumours is the apparent myo-lnositol (ml) intensity (ca 3.55 ppm) at short echo times, although glycine (gly) may also contribute in vivo to this resonance. The purpose of this study was to quantitatively evaluate the ml + gly contribution to the recorded spectral pattern in vivo and correlate it with in vitro data obtained from perchloric acid extraction of tumour biopsies. Patient spectra (n = 95) at 1.5T at short (20-31 ms) and long (135-136 ms) echo times were obtained from the INTERPRET MRS database (http://gabrmn.uab.eslinterpretvalidateddbl). Phantom spectra were acquired with a comparable protocol. Spectra were automatically processed and the ratios of the (ml + gly) to Cr peak heights ((ml + gly)/Cr) calculated. Perchloric acid extracts of brain tumour biopsies were analysed by high-resolution NMR at 9.4T. The ratio (ml + gly)/Cr decreased significantly with astrocytic grade in vivo between low-grade astrocytoma (A2) and glioblastoma multiforme (GBM). In vitro results displayed a somewhat different tendency, with anaplastic astrocytomas having significantly higher (ml + gly)/Cr than A2 and GBM. The discrepancy between in vivo and in vitro data suggests that the NMR visibility of glycine in glial brain tumours is restricted in vivo.

Oxidation behavior and area specific resistance of La, Cu and B alloyed Fe-22Cr ferritic steels for solid oxide fuel cell interconnects

NASA Astrophysics Data System (ADS)

Swaminathan, Srinivasan; Ko, Yoon Seok; Lee, Young-Su; Kim, Dong-Ik

2017-11-01

Two Fe-22 wt% Cr ferritic stainless steels containing varying concentrations of La (0.14 or 0.52 wt%), Cu (0.17 or 1.74 wt%) and B (48 or 109 ppm) are investigated with respect to oxidation behavior and high temperature area specific resistance (ASR) of the surface oxide scales. To determine the oxidation resistance of developed steels, continuous isothermal oxidation is carried out at 800 °C in air, for 2000 h, and their thermally grown oxide scale is characterized using dynamic SIMS, SEM/EDX, XRD and GI-XRD techniques. To assess their electrical performance, the ASR measurement by four-point probe method is conducted at 800 °C in air, for 400 h. In higher La content steel, the La-oxides at the scale/alloy interface promotes the oxygen transport which resulted in sub-surface oxidation of Mn, Cr, Ti and Al. Moreover, the inward growth of oxides contributes to increase of Fe-Cr alloy protrusions within the scale, which reduced the ASR. In contrast, sub-surface oxidation is reduced in high Cu-alloyed steel by segregated Cu at the scale/alloy interface. Thus, addition of Cu is effective to oxidation resistance and also to better electrical performance. However, no obvious impact of B on the scale sequence and/or ASR is observed.

Influence of nanovoids on α-α' phase separation in FeCrAl oxide dispersion strengthened alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capdevila, Carlos; Aranda, M. M.; Rememnteria, R.

2015-08-10

The presence of nanovoids in the vicinity of oxide particles in FeCrAl oxide dispersion strengthened (ODS) alloy has been identified. These nanovoids are inherent to the manufacturing route and remain quite resistant during heat treatments. Positron annihilation spectroscopy (PAS) experiments demonstrate that these nanovoids trap Cr inside thereby reducing the Cr-content in the matrix. In conclusion, this might lead to a delay in the α–α' phase separation process as observed by atom probe tomography (APT).

Chromium VI administration induces oxidative stress in hypothalamus and anterior pituitary gland from male rats.

PubMed

Nudler, Silvana I; Quinteros, Fernanda A; Miler, Eliana A; Cabilla, Jimena P; Ronchetti, Sonia A; Duvilanski, Beatriz H

2009-03-28

Hexavalent chromium (Cr VI)-containing compounds are known carcinogens which are present in industrial settings and in the environment. The major route of chromium exposure for the general population is oral intake. Previously we have observed that Cr VI affects anterior pituitary secretion and causes oxidative stress in vitro. The aim of the present work was to investigate if in vivo Cr VI treatment (100 ppm of Cr VI in drinking water for up 30 days) causes oxidative stress in hypothalamus and anterior pituitary gland from male rats. This treatment produced a 4-fold increase of chromium content in hypothalamus and 10-fold increase in anterior pituitary gland. Lipid peroxidation showed a significant increase in hypothalamus and anterior pituitary. Cr VI augmented superoxide dismutase activity in anterior pituitary gland and glutathione reductase activity in hypothalamus, but glutathione peroxidase and catalase activities remained unchanged in both tissues. Heme oxygenase-1 mRNA expression significantly rose in both tissues. Metallothionein 1 mRNA content increased in anterior pituitary and metallothionein 3 mRNA increased in hypothalamus. These results show, for the first time, that oral chronic administration of Cr VI produces oxidative stress on the hypothalamus and anterior pituitary gland which may affect normal endocrine function.

Effect of various selenium doses on chromium(IV)-induced nephrotoxicity in a male chicken model.

PubMed

Wan, Huiyu; Zhu, Yiran; Chen, Peng; Wang, Yang; Hao, Pan; Cheng, Ziqiang; Liu, Yongxia; Liu, Jianzhu

2017-05-01

Our study aimed to explore whether Na 2 SeO 3 (Se) can alleviate the nephrotoxicity induced by K 2 Cr 2 O 7 [Cr(VI)]. One hundred and five male chickens were randomly divided into seven groups with 15 chickens each group: The 6 experimental groups received K 2 Cr 2 O 7 alone or in combination with 0.31, 0.63, 1.25, 2.50, and 5.00 mg/kg for 42 days, respectively, while control group was treated with equivalent water. Exposure to Cr(VI) significantly increased MDA contents and organ coefficient, whereas decreased T-SOD activities, Ca 2+ -ATPase activities, mitochondrial membrane potential and GSH contents, and histological studies demonstrated renal damage. Above indicators were restored by Se supplement (0.31, 0.63, and 1.25 mg/kg), in which supplement with 0.63 mg/kg Se developed more effectively than the other two groups; on the contrary, in the groups of Se supplement with 2.50 and 5.00 mg/kg, the above indicators were not ameliorated and even exacerbated. This study demonstrated that Cr(VI) can result in kidney oxidative damage in male chickens, and Se of certain dose has the protective effects against Cr(VI)-induced nephrptoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Corrosion Behavior and Durability of Low-Alloy Steel Rebars in Marine Environment

NASA Astrophysics Data System (ADS)

Liu, Ming; Cheng, Xuequn; Li, Xiaogang; Yue, Pan; Li, Jun

2016-11-01

The corrosion resistance of Cr-modified low-alloy steels and HRB400 carbon steel was estimated using the open-circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopic, and weight loss methods in simulated concrete pore solution. Results show that Cr-modified steels exhibit a higher corrosion resistance with a higher critical chloride level (CTL), lower corrosion current density, and higher impedance than carbon steel. The CTL of the steels significantly reduces with increasing temperature. Weight loss measurement shows that the Cr-modified steels exhibit low corrosion rates and small corrosion pitting. The primary constituents of the corrosion scales are Fe2O3, Fe3O4, β-FeOOH, γ-FeOOH, and α-FeOOH. A large amount of α-FeOOH could be detected in the Cr-modified steel corrosion products. Moreover, the Cr-modified steels demonstrate a higher durability than HRB400 carbon steel.

Variations of trace element concentration of magnetite and ilmenite from the Taihe layered intrusion, Emeishan large igneous province, SW China: Implications for magmatic fractionation and origin of Fe-Ti-V oxide ore deposits

NASA Astrophysics Data System (ADS)

She, Yu-Wei; Song, Xie-Yan; Yu, Song-Yue; He, Hai-Long

2015-12-01

In situ LA-ICP-MS trace elemental analysis has been applied to magnetite and ilmenite of the Taihe layered intrusion, Emeishan large igneous province, SW China, in order to understand better fractionation processes of magma and origin of Fe-Ti-V oxide ore deposits. The periodic reversals in Mg, Ti, Mn in magnetite and Mg, Sc in ilmenite are found in the Middle Zone of the intrusion and agree with fractionation trends as recorded by olivine (Fo), plagioclase (An) and clinopyroxene (Mg#) compositions. These suggest the Taihe intrusion formed from open magma chamber processes in a magma conduit with multiple replenishments of more primitive magmas. The V and Cr of magnetite are well correlated with V and Cr of clinopyroxene indicating that they became liquidus phases almost simultaneously at an early stage of magma evolution. Ilmenite from the Middle and Upper Zones shows variable Cr, Ni, V, Mg, Nb, Ta and Sc contents indicating that ilmenite at some stratigraphic levels crystallized slightly earlier than magnetite and clinopyroxene. The early crystallization of magnetite and ilmenite is the result of the high FeOt and TiO2 contents in the parental magma. The ilmenite crystallization before magnetite in the Middle and Upper Zones can be attributed to higher TiO2 content of the magma due to the remelting of pre-existing ilmenite in a middle-level magma chamber. Compared to the coeval high-Ti basalts, the relatively low Zr, Hf, Nb and Ta contents in both magnetite and ilmenite throughout the Taihe intrusion indicate that they crystallized from Fe-Ti-(P)-rich silicate magmas. Positive correlations of Ti with Mg, Mn, Sc and Zr of magnetite, and Zr with Sc, Hf and Nb of ilmenite also suggest that magnetite and ilmenite crystallized continuously from the homogeneous silicate magma rather than an immiscible Fe-rich melt. Therefore, frequent replenishments of Fe-Ti-(P)-rich silicate magma and gravitational sorting and settling are crucial for the formation the massive and apatite-rich disseminated ores in the Lower and Middle Zones of the Taihe intrusion.

Hot hardness of nickel-rich nickel-chromium-aluminum alloys

NASA Technical Reports Server (NTRS)

Levine, S. R.

1976-01-01

Rockwell A hardness of cast nickel-chromium-aluminum (NiCrAl) alloys was examined from ambient to 1150 K and compared to cast NiAl and IN-100. Alloy constitution was either gamma, gamma prime + gamma or gamma + beta + alpha + gamma prime. Below 1000 K beta containing NiCrAl alloys have hardnesses comparable to IN-100; above 1000 K they soften faster than IN-100. At 1150 K the hardness of beta-containing NiCrAl alloys decreases with increasing beta-content. The beta-containing NiCrAl alloys were harder than beta-NiAl. The ultimate tensile strengths of the NiCrAl alloys were estimated. The effects of NiCrAl coatings on strength and fatigue life of cooled turbine components were deduced.

Triclinic-monoclinic-orthorhombic (T-M-O) structural transitions in phase diagram of FeVO4-CrVO4 solid solutions

NASA Astrophysics Data System (ADS)

Bera, Ganesh; Reddy, V. R.; Rambabu, P.; Mal, P.; Das, Pradip; Mohapatra, N.; Padmaja, G.; Turpu, G. R.

2017-09-01

Phase diagram of FeVO4-CrVO4 solid solutions pertinent with structural and magnetic phases is presented with unambiguous experimental evidences. Solid solutions Fe1-xCrxVO4 (0 ≤ x ≤ 1.0) were synthesized through the standard solid state route and studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectra of X-rays, Raman spectroscopy, d.c. magnetization, and 57Fe Mössbauer spectroscopic studies. FeVO4 and CrVO4 were found to be in triclinic (P-1 space group) and orthorhombic structures (Cmcm space group), respectively. Cr incorporation into the FeVO4 lattice leads to the emergence of a new monoclinic phase dissimilar to the both end members of the solid solutions. In Fe1-xCrxVO4 up to x = 0.10, no discernible changes in the triclinic structure were found. A new structural monoclinic phase (C2/m space group) emerges within the triclinic phase at x = 0.125, and with the increase in Cr content, it gets stabilized with clear single phase signatures in the range of x = 0.175-0.25 as evidenced by the Rietveld analysis of the structures. Beyond x = 0.33, orthorhombic phase similar to CrVO4 (Cmcm space group) emerges and coexists with a monoclinic structure up to x = 0.85, which finally tends to stabilize in the range of x = 0.90-1.00. The Raman spectroscopic studies also confirm the structural transition. FeVO4 Raman spectra show the modes related to three nonequivalent V ions in the triclinic structure, where up to 42 Raman modes are observed in the present study. With the stabilization of structures having higher symmetry, the number of Raman modes decreases and the modes related to symmetry inequivalent sites collate into singular modes from the doublet structure. A systematic crossover from two magnetic transitions in FeVO4, at 21.5 K and 15.4 K to single magnetic transition in CrVO4, at 71 K (antiferromagnetic transition), is observed in magnetization studies. The intermediate solid solution with x = 0.15 shows two magnetic transitions, whereas in the compound with x = 0.33 one of the magnetic transitions disappears. 57Fe Mössbauer spectroscopic studies show a finger print evidence for disappearance of non-equivalent sites of Fe as the structure changes from Triclinic-Monoclinic-Orthorhombic phases with the increasing Cr content in Fe1-xCrxVO4. Comprehensive studies related to the structural changes in Fe1-xCrxVO4 solid solutions lead us to detailed phase diagrams which shall be characteristic for room temperature structural and temperature dependent magnetic transitions in these solid solutions, respectively.

The influence of Ga doping on structural magnetic and dielectric properties of NiCr0.2Fe1.8O4 spinel ferrite

NASA Astrophysics Data System (ADS)

Ajmal, Muhammad; Islam, M. U.; Ashraf, Ghulam Abbas; Nazir, Muhammad Aamir; Ghouri, M. I.

2017-12-01

A series of spinel ferrites NiCr0.2GaxFe1.8-xO4 (x=0.00, 0.002, 0.04, 0.06, 0.08) was prepared by co precipitation technique. The influence of rare earth element Ga ions the structural dielectric and magnetic properties of NiCr0.2Fe1.8O4 ferrites was investigated. The X-ray diffraction confirmed the phase precipitated out was pure spinel phase with few traces of secondary phases. The crystallite size decreases and density increases with the increases of Ga contents. The magnetic moment, saturation magnetization and remanent magnetization increased with addition of Ga ions in spinel ferrite. The dielectric constant is described that it decreases more suddenly at low frequencies as compare at higher frequencies. The decrease in dielectric loss with frequency follows Deby's relaxation phenomena. Both the variation in tan loss and dielectric loss with frequency shows a similar. AC conductivity increases with the increases of frequency which inversely proportional to concentration of Ga3+ ions follows Jonscher law. These Gallium Chromium doped nickel ferrites are very helpful for high frequency switching devices.

Effects of feeding strategy during a short finishing period on performance, carcass and meat quality in previously-grazed young bulls.

PubMed

Cerdeño, A; Vieira, C; Serrano, E; Lavín, P; Mantecón, A R

2006-04-01

Twenty-one Brown Swiss×Limousin young bulls reared on pasture were housed for a short finishing period (60 days). CA group (concentrate-ad libitum group) received concentrate and straw ad libitum for the whole finishing period. CR group (concentrate-restricted group) received 4kg of concentrate/animal per day and ad libitum alfalfa hay throughout the 60days. CRA group (concentrate-restricted/ad libitum group) received the same diet as CR group for the first 30days and the same diet as CA group for the last 30days. CA and CRA groups presented higher fatness values. Myoglobin concentration in muscle was highest in CA group (P<0.05) and carotene content in subcutaneous fat was highest in CR group (P<0.01), while Warner-Bratzler shear force and sensory traits were unaffected (P>0.05). It is concluded that, in this type of young animal, 4kg concentrate plus ad libitum alfalfa hay for a 60-day finishing period, despite lower fatness, provides carcasses and meat with acceptable quality characteristics, similar to those obtained from ad libitum fed animals for the same period.

Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China

PubMed Central

Yang, Jie; Teng, Yanguo; Song, Liuting; Zuo, Rui

2016-01-01

Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area. PMID:27992518

Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China.

PubMed

Yang, Jie; Teng, Yanguo; Song, Liuting; Zuo, Rui

2016-01-01

Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area.

High Temperature Strengthening in 12Cr-W-Mo Steels by Controlling the Formation of Delta Ferrite

NASA Astrophysics Data System (ADS)

Wang, Shushen; Chang, Li; Lin, Deye; Chen, Xiaohua; Hui, Xidong

2014-09-01

Novel 12Cr-W-Mo-Co heat resistance steels (HRSs) with excellent mechanical properties have been developed for ultra-supercritical (USC) applications above 923 K (650 °C). The thermal analysis of the present steels indicates that the remelting temperature of secondary phases is increased by Co alloying, resulting in the improvement of microstructural stability. Delta ferrite in these HRSs is completely suppressed as the content of Co is increased up to 5 pct. The room temperature tensile strength (TS), yield strength (YS), and the elongation (EL) of the HRS with 5 pct Co reach 887.9, 652.6 MPa, and 21.07 pct, respectively. At 948 K (675 °C), the TS and YS of the HRS with 5 pct Co attain 360 and 290 MPa, respectively, which are higher than those of T/P122 steel by 27.4 and 22.1 pct, respectively. TEM study of the microstructure confirmed that the strengthening effects for these 12Cr-W-Mo-Co HRSs are attributed to the suppression of delta ferrite, the formation of fine martensitic laths with substructure, dislocation networks and walls, and the precipitation of second nanoscale phases.

The volatilization of heavy metals during co-combustion of food waste and polyvinyl chloride in air and carbon dioxide/oxygen atmosphere.

PubMed

Ke, Chuncheng; Ma, Xiaoqian; Tang, Yuting; Zheng, Weihua; Wu, Zhendong

2017-11-01

The volatilization of three heavy metals (Cd, Cr and Zn) during food waste and PVC and their blending combustion in N 2 /O 2 or CO 2 /O 2 atmosphere in a lab-scale tubular furnace was investigated. The concentration of heavy metals in combustion ash was decreased with the increment of furnace temperature in most cases. The replacement of 80N 2 /20O 2 by 80CO 2 /20O 2 decreased the volatilization rate of Cd and Cr, but increased Zn. The increased amount of PVC added into food waste led to less content of Zn in combustion ash, 5% PVC added into food waste decreased the volatilization rate of Cr but 15% PVC added led to the higher volatilization. The volatilization rate of Zn in 70CO 2 /30O 2 was significantly lower than in 85CO 2 /15O 2 or 80CO 2 /20O 2 . The result contributes to the understanding of heavy metal volatilization during incineration and emission control of MSW oxy-fuel combustion. Copyright © 2017 Elsevier Ltd. All rights reserved.

A history of violence: Insights into post-accretionary heating in carbonaceous chondrites from volatile element abundances, Zn isotopes and water contents

NASA Astrophysics Data System (ADS)

Mahan, Brandon; Moynier, Frédéric; Beck, Pierre; Pringle, Emily A.; Siebert, Julien

2018-01-01

Carbonaceous chondrites (CCs) may have been the carriers of water, volatile and moderately volatile elements to Earth. Investigating the abundances of these elements, their relative volatility, and isotopes of state-change tracer elements such as Zn, and linking these observations to water contents, provide vital information on the processes that govern the abundances and isotopic signatures of these species in CCs and other planetary bodies. Here we report Zn isotopic data for 28 CCs (20 CM, 6 CR, 1 C2-ung, and 1 CV3), as well as trace element data for Zn, In, Sn, Tl, Pb, and Bi in 16 samples (8 CM, 6 CR, 1 C2-ung, and 1 CV3), that display a range of elemental abundances from case-normative to intensely depleted. We use these data, water content data from literature and Zn isotopes to investigate volatile depletions and to discern between closed and open system heating. Trace element data have been used to construct relative volatility scales among the elements for the CM and CR chondrites. From least volatile to most, the scale in CM chondrites is Pb-Sn-Bi-In-Zn-Tl, and for CR chondrites it is Tl-Zn-Sn-Pb-Bi-In. These observations suggest that heated CM and CR chondrites underwent volatile loss under different conditions to one another and to that of the solar nebula, e.g. differing oxygen fugacities. Furthermore, the most water and volatile depleted samples are highly enriched in the heavy isotopes of Zn. Taken together, these lines of evidence strongly indicate that heated CM and CR chondrites incurred open system heating, stripping them of water and volatiles concomitantly, during post-accretionary shock impact(s).

Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys.

PubMed

Li, Kai Chun; Prior, David J; Waddell, J Neil; Swain, Michael V

2015-12-01

The objective of this study was to identify the different microstructures produced by CC, PM and as-cast techniques for Co-Cr alloys and their phase stability following porcelain firings. Three bi-layer porcelain veneered Co-Cr specimens and one monolithic Co-Cr specimen of each alloy group [cast, powder metallurgy (PM), CAD/CAM (CC)] were manufactured and analyzed using electron backscatter diffraction (EBSD), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Specimens were treated to incremental numbers of porcelain firings (control 0, 5, 15) with crystallographic data, grain size and chemical composition subsequently obtained and analyzed. EBSD datasets of the cast alloy indicated large grains >200 μm whereas PM and CC alloy consisted of mean arithmetic grain sizes of 29.6 μm and 19.2 μm respectively. XRD and EBSD results both indicated the highest increase in hcp content (>13vol%) for cast Co-Cr alloy after treatment with porcelain firing while PM and CC indicated <2vol% hcp content. A fine grain interfacial layer developed on all surfaces of the alloy after porcelain firing. The depth of this layer increased with porcelain firings for as-cast and PM but no significant increase (p>.05) was observed in CC. EDS line scans indicated an increase in Cr content at the alloy surface after porcelain firing treatment for all three alloys. PM and CC produced alloy had superior fcc phase stability after porcelain firings compared to a traditional cast alloy. It is recommended that PM and CC alloys be used for porcelain-fused-to-metal restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Bayesian Geostatistical Analysis and Ecoclimatic Determinants of Corynebacterium pseudotuberculosis Infection among Horses

PubMed Central

Boysen, Courtney; Davis, Elizabeth G.; Beard, Laurie A.; Lubbers, Brian V.; Raghavan, Ram K.

2015-01-01

Kansas witnessed an unprecedented outbreak in Corynebacterium pseudotuberculosis infection among horses, a disease commonly referred to as pigeon fever during fall 2012. Bayesian geostatistical models were developed to identify key environmental and climatic risk factors associated with C. pseudotuberculosis infection in horses. Positive infection status among horses (cases) was determined by positive test results for characteristic abscess formation, positive bacterial culture on purulent material obtained from a lanced abscess (n = 82), or positive serologic evidence of exposure to organism (≥1:512)(n = 11). Horses negative for these tests (n = 172)(controls) were considered free of infection. Information pertaining to horse demographics and stabled location were obtained through review of medical records and/or contact with horse owners via telephone. Covariate information for environmental and climatic determinants were obtained from USDA (soil attributes), USGS (land use/land cover), and NASA MODIS and NASA Prediction of Worldwide Renewable Resources (climate). Candidate covariates were screened using univariate regression models followed by Bayesian geostatistical models with and without covariates. The best performing model indicated a protective effect for higher soil moisture content (OR = 0.53, 95% CrI = 0.25, 0.71), and detrimental effects for higher land surface temperature (≥35°C) (OR = 2.81, 95% CrI = 2.21, 3.85) and habitat fragmentation (OR = 1.31, 95% CrI = 1.27, 2.22) for C. pseudotuberculosis infection status in horses, while age, gender and breed had no effect. Preventative and ecoclimatic significance of these findings are discussed. PMID:26473728

Bayesian Geostatistical Analysis and Ecoclimatic Determinants of Corynebacterium pseudotuberculosis Infection among Horses.

PubMed

Boysen, Courtney; Davis, Elizabeth G; Beard, Laurie A; Lubbers, Brian V; Raghavan, Ram K

2015-01-01

Kansas witnessed an unprecedented outbreak in Corynebacterium pseudotuberculosis infection among horses, a disease commonly referred to as pigeon fever during fall 2012. Bayesian geostatistical models were developed to identify key environmental and climatic risk factors associated with C. pseudotuberculosis infection in horses. Positive infection status among horses (cases) was determined by positive test results for characteristic abscess formation, positive bacterial culture on purulent material obtained from a lanced abscess (n = 82), or positive serologic evidence of exposure to organism (≥ 1:512)(n = 11). Horses negative for these tests (n = 172)(controls) were considered free of infection. Information pertaining to horse demographics and stabled location were obtained through review of medical records and/or contact with horse owners via telephone. Covariate information for environmental and climatic determinants were obtained from USDA (soil attributes), USGS (land use/land cover), and NASA MODIS and NASA Prediction of Worldwide Renewable Resources (climate). Candidate covariates were screened using univariate regression models followed by Bayesian geostatistical models with and without covariates. The best performing model indicated a protective effect for higher soil moisture content (OR = 0.53, 95% CrI = 0.25, 0.71), and detrimental effects for higher land surface temperature (≥ 35°C) (OR = 2.81, 95% CrI = 2.21, 3.85) and habitat fragmentation (OR = 1.31, 95% CrI = 1.27, 2.22) for C. pseudotuberculosis infection status in horses, while age, gender and breed had no effect. Preventative and ecoclimatic significance of these findings are discussed.

Spectroscopic and dielectric response of zinc bismuth phosphate glasses as a function of chromium content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, P. Srinivasa; Babu, P. Ramesh; Vijay, R.

2014-09-15

Graphical abstract: 20ZnF{sub 2}–(20 − x)Bi{sub 2}O{sub 3}–60P{sub 2}O{sub 5}:xCr{sub 2}O{sub 3} (0 ≤ x ≤2 mol%) glasses are prepared by melt quenching technique. The optical absorption spectra of present glasses are analyzed as a function of chromium content. The absorption bands are assigned to {sup 4}A{sub 2g}(F) ⟶ {sup 4}T{sub 1g}(F), {sup 4}A{sub 2g}(F) ⟶ {sup 4}T{sub 2g}(F), {sup 4}A{sub 2g}(F) ⟶ {sup 2}T{sub 1g}(G) and {sup 4}A{sub 2g}(F) ⟶ {sup 2}E{sub g}(G) transitions of Cr{sup 3+} ions. - Highlights: • ZnF{sub 2}–Bi{sub 2}O{sub 3}–P{sub 2}O{sub 5}:Cr{sub 2}O{sub 3} glasses were prepared by melt quenching and annealing. • Spectroscopicmore » and dielectric properties of chromium ions were investigated. • ESR and optical absorption spectra indicate the co-existence of Cr{sup 6+} ions with Cr{sup 5+} ions and Cr{sup 3+} ions. • Cr{sup 3+} ions act as modifiers and influence the semiconducting nature of the glass system. - Abstract: 20ZnF{sub 2}–(20 − x)Bi{sub 2}O{sub 3}–60P{sub 2}O{sub 5}:xCr{sub 2}O{sub 3} (0 ≤ x ≤2 mol%) glasses are prepared by melt quenching technique. Amorphous nature of these samples is confirmed by X-ray diffraction (XRD) analysis. FTIR study reveals bands due to CrO{sub 6}(o{sub d}) and CrO{sub 4}{sup 2−}(T{sub d}) units along with conventional phosphate groups. The optical absorption and ESR studies of present glasses are analyzed as a function of chromium content. The absorption bands are assigned to {sup 4}A{sub 2g}(F) ⟶ {sup 4}T{sub 1g}(F), {sup 4}A{sub 2g}(F) ⟶ {sup 4}T{sub 2g}(F), {sup 4}A{sub 2g}(F) ⟶ {sup 2}T{sub 1g}(G) and {sup 4}A{sub 2g}(F) ⟶ {sup 2}E{sub g}(G) transitions of Cr{sup 3+} ions. The highest concentration of Cr{sup 3+} ions (in octahedral sites, with network modifying positions) is found in the sample with 2.0 mol% of Cr{sub 2}O{sub 3}. The analysis of dielectric properties indicates a gradual increase in semiconducting character with increase in the concentration of Cr{sub 2}O{sub 3} from 0.2 to 2.0 mol%. The studies on dielectric breakdown strength identify the highest insulating strength for lowest mol% of Cr{sub 2}O{sub 3} in the present samples.« less

In-situ electrochemical-AFM study of localized corrosion of AlxCoCrFeNi high-entropy alloys in chloride solution

NASA Astrophysics Data System (ADS)

Shi, Yunzhu; Collins, Liam; Balke, Nina; Liaw, Peter K.; Yang, Bin

2018-05-01

In-situ electrochemical (EC)-AFM is employed to investigate the localized corrosion of the AlxCoCrFeNi high-entropy alloys (HEAs). Surface topography changes on the micro/sub-micro scale are monitored at different applied anodizing potentials in a 3.5 wt% NaCl solution. The microstructural evolutions with the increased Al content in the alloys are characterized by SEM, TEM, EDS and EBSD. The results show that by increasing the Al content, the microstructure changes from single solid-solution to multi-phases, leading to the segregations of elements. Due to the microstructural variations in the AlxCoCrFeNi HEAs, localized corrosion processes in different ways after the breakdown of the passive film, which changes from pitting to phase boundary corrosion. The XPS results indicate that an increased Al content in the alloys/phases corresponds to a decreased corrosion resistance of the surface passive film.

Changes in macrominerals, trace elements and pigments content during lettuce (Lactuca sativa L.) growth: influence of soil composition.

PubMed

Pinto, Edgar; Almeida, Agostinho A; Aguiar, Ana A R M; Ferreira, Isabel M P L V O

2014-01-01

Changes in macrominerals, trace elements and photosynthetic pigments were monitored at 5 stages of lettuce growth. Plants were grown in three experimental agriculture greenhouse fields (A1, A2 and A3). Soil composition was also monitored to understand its influence on lettuce composition. In general, the content of macrominerals, trace elements, chlorophylls and carotenoids decreased during lettuce growth and consequently, high nutritional value was observed at younger stages. A2 lettuces showed an increase of Fe, Al, Cr, V and Pb due to the different soil physicochemical parameters. Multiple linear regression analysis with stepwise variable selection, indicated that soil characteristics, namely, pH(CaCl2) for Fe and Cr, silt and fine-sand for Al and V, OM for Al and Pb, coarse-sand and CEC for Cr, had a key role determining element bioavailability and plant mineral content. Thus, lettuce nutritional value was strongly dependent of growth stage and soil characteristics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of processing on the proximate and metal contents in three fish species from Nigerian coastal waters

PubMed Central

Bassey, Francisca I; Oguntunde, Fehintola C; Iwegbue, Chukwujindu M A; Osabor, Vincent N; Edem, Christopher A

2014-01-01

The effects of culinary practices such as boiling, frying, and grilling on the proximate compositions and concentrations of metals (Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg) in commonly consumed fish species from the Nigerian coastal waters were investigated. The selected fish species were Polydactylus quadratifilis, Chrysicthys nigrodigitatus and Cynoglossus senegalensis. The culinary practices lead to increased protein, fat, and ash contents and decreased moisture contents of these fish species. The culinary practices resulted significant increase in the concentrations of most of the studied metals and decrease in the concentrations of Fe, Cr, and Pb in some fish types. The concentrations and estimated dietary intakes of Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg from consumption of the processed fish were within their statutory safe limits. The individual metal target hazard quotient (THQ) values and the total THQs were less than 1 which indicates that no health risks would arise from the long-term consumption of these fish species. PMID:24936297

[Study on pollution evaluation of heavy metal in surface soil of the original site of Qingdao North Station].

PubMed

Zhu, Lei; Jia, Yong-gang; Pan, Yu-ying

2013-09-01

The determination of pollution extent and health risk assessment are the premise of heavy metal contaminated site remediation. The content of Cu, Cr, Pb, Cd, Zn, Ni in Qingdao North Station was detected, and the correlation of the 6 kinds of heavy metal content was analyzed. The pollution extent in excess of background values was characterized by anthropogenic influence multiple, and the pollution of heavy metal in soil was evaluated using geoaccumulation index and a new method which connects geoaccumulation index with Nemero index. Finally, human health risk assessment was carried out with health risk assessment model for heavy metal content. The results showed that Qingdao North Station soil were polluted by heavy metals. Six heavy metal pollution levels were: Cd > Cu > Ni > Pb > Cr > Zn, and Cd had reached the severity pollution level, Cu and Ni followed by, Cr, Pb and Zn were in minor pollution level. The order of coefficient variation in all heavy metals was: Cd > Ni > Cr > Zn > Pb > Cu. Within the study area soil heavy metal distribution was different, but overall discrepancy was small. The order of non-cancer hazards of heavy metals in soil was Cr > Pb > Cu > Ni > Cd > Zn, and the order of carcinogen risks of heavy metals was Ni > Cd. The non-cancer hazard and carcinogen risks values of metals were both lower than that their threshold values. They were not the direct threats to human health.

FT-Raman spectroscopic analysis of Nd:YAG and Er,Cr:YSGG laser irradiated enamel for preventive purposes

NASA Astrophysics Data System (ADS)

Ana, P. A.; Kauffmann, C. M. F.; Bachmann, L.; Soares, L. E. S.; Martin, A. A.; Gomes, A. S. L.; Zezell, D. M.

2014-03-01

This study evaluated the effect of combining laser irradiation with fluoride on an enamel microstructure and demineralization by FT-Raman spectroscopy (FTRS). Eighty human enamel slabs were divided into eight groups: (G1) untreated; (G2) acidulated phosphate fluoride application (APF—1.23% F- for 4 min) (G3) Nd:YAG irradiation (84.9 J cm-2, 60 mJ/pulse) (G4) Nd:YAG + APF; (G5) APF + Nd:YAG; (G6) Er,Cr:YSGG irradiation (2.8 J cm-2, 12.5 mJ/pulse) (G7) Er,Cr:YSGG + APF; and (G8) APF + Er,Cr:YSGG. After treatment, the samples were submitted to a ten-day pH-cycling model. Chemical changes were determined on the slabs before and after treatment, and also after pH-cycling, by FTRS in the range 400-4000 cm-1. The inorganic bands at 440, 590, 870, 960, 1100 cm-1, and the organic bands at 1270, 1450, 1670, 2945 cm-1 were considered. Demineralization promoted reduction in organic contents; Nd:YAG laser irradiation promoted loss of carbonate and organic content, while Er,Cr:YSGG did not produce significant changes in the relative band intensities of organic and inorganic contents of the enamel. In lased samples, no effects caused by pH-cycling on enamel were observed. In conclusion, laser treatment and its association with fluoride can somehow interfere with the demineralization dynamics, reducing its effects over the enamel.

Effect of Mo contents on corrosion behaviors of welded duplex stainless steel

NASA Astrophysics Data System (ADS)

Bae, Seong Han; Lee, Hae Woo

2013-05-01

The corrosion behaviour and change of the phase fraction in welded 24Cr Duplex stainless steel was investigated for different chemical composition ranges of Mo contents. Filler metal was produced by fixing the contents of Cr, Ni, N, and Mn while adjusting the Mo content to 0.5, 1.4, 2.5, 3.5 wt%. The δ-ferrite fraction was observed to increase as the content of Mo increased. A polarisation test conducted in a salt solution, indicated the pitting corrosion potential increased continuously to 3.5 wt% Mo, while the corrosion potential changed most between 0.5 and 1.41 wt% Mo. The location of the pitting corrosion in 0.5 wt% Mo steel was randomly distributed, but it occurred selectively at the grain boundary between the γ- and δ-ferrite phases in 1.4, 2.5 and 3.5 wt% Mo steel. Energy dispersive X-ray spectroscopy mapping analysis showed that areas deficient in Cr, Mo, and Ni occurred around the grain boundary of the γ- and δ-ferrite phases. Non-metallic inclusions are thought to act as initiation points for the pitting corrosion that occurs in the salt solution initially as a result of the potential difference between the matrix structure and the incoherent inclusions.

Effects of iron content in Ni-Cr-xFe alloys and immersion time on the oxide films formed in a simulated PWR water environment

NASA Astrophysics Data System (ADS)

Ru, Xiangkun; Lu, Zhanpeng; Chen, Junjie; Han, Guangdong; Zhang, Jinlong; Hu, Pengfei; Liang, Xue

2017-12-01

The iron content in Ni-Cr-xFe (x = 0-9 at.%) alloys strongly affected the properties of oxide films after 978 h of immersion in the simulated PWR primary water environment at 310 °C. Increasing the iron content in the alloys increased the amount of iron-bearing polyhedral spinel oxide particles in the outer oxide layer and increased the local oxidation penetrations into the alloy matrix from the chromium-rich inner oxide layer. The effects of iron content in the alloys on the oxide film properties after 500 h of immersion were less significant than those after 978 h. Iron content increased, and chromium content decreased, in the outer oxide layer with increasing iron content in the alloys. Increasing the immersion time facilitated the formation of the local oxidation penetrations along the matrix/film interface and the nickel-bearing spinel oxides in the outer oxide layer.

Serum and urinary cystatin C in cats with feline immunodeficiency virus infection and cats with hyperthyroidism.

PubMed

Ghys, Liesbeth Fe; Paepe, Dominique; Taffin, Elien Rl; Vandermeulen, Eva; Duchateau, Luc; Smets, Pascale My; Delanghe, Joris; Daminet, Sylvie

2016-08-01

The objective of this study was to investigate serum cystatin C (sCysC) and urinary cystatin C (uCysC) in cats with hyperthyroidism and cats with feline immunodeficiency virus (FIV). Thirty cats with FIV, 26 hyperthyroid cats and 28 healthy cats were included. sCysC and uCysC:creatinine (uCysC/uCr) ratio were measured with a human particle-enhanced nephelometric immunoassay, previously validated for feline CysC measurement. Routine renal variables (serum creatinine [sCr], urine specific gravity, urinary protein:creatinine ratio [UPC]) were also measured in the three groups. Cats with hyperthyroidism had significantly higher sCysC and higher uCysC/uCr ratio, lower sCr and a higher UPC than healthy cats. Cats with FIV infection did not show a significantly higher sCysC concentration but had a significantly higher sCr and UPC than healthy cats. uCysC could be detected in only four of them. This study demonstrated that sCysC is increased in cats with hyperthyroidism, in contrast with sCr, but not in cats with FIV. Many hyperthyroid cats, but only four cats with FIV, had an elevated uCysC/uCr ratio. Further studies may reveal if uCysC might be a valuable marker for tubular dysfunction in cats. © The Author(s) 2015.

The MSFR as a flexible CR reactor: the viewpoint of safety

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fiorina, C.; Cammi, A.; Franceschini, F.

2013-07-01

In this paper, the possibility has first been discussed of using the liquid-fuelled Molten Salt Fast Reactor (MSFR) as a flexible conversion ratio (CR) reactor without design modification. By tuning the reprocessing rate it is possible to determine the content of fission products in the core, which in turn can significantly affect the neutron economy without incurring in solubility problems. The MSFR can thus be operated as U-233 breeder (CR>1), iso-breeder (CR=1) and burner reactor (CR<1). In particular a 40 year doubling time can be achieved, as well as a considerable Transuranics and MA (minor actinide) burning rate equal tomore » about 150 kg{sub HN}/GWE-yr. The safety parameters of the MSFR have then been evaluated for different fuel cycle strategies. Th use and a softer spectrum combine to give a strong Doppler coefficient, one order of magnitude higher compared to traditional fast reactors (FRs). The fuel expansion coefficient is comparable to the Doppler coefficient and is only mildly affected by core compositions, thus assisting the fuel cycle flexibility of the MSFR. βeff and generation time are comparable to the case of traditional FRs, if a static fuel is assumed. A notable reduction of βeff is caused by salt circulation, but a low value of this parameter is a limited concern in the MSFR thanks to the lack of a burnup reactivity swing and of positive feedbacks. A simple approach has also been developed to evaluate the MSFR capabilities to withstand all typical double-fault accidents, for different fuel cycle options.« less

Enrichment and sources of trace metals in roadside soils in Shanghai, China: A case study of two urban/rural roads.

PubMed

Yan, Geng; Mao, Lingchen; Liu, Shuoxun; Mao, Yu; Ye, Hua; Huang, Tianshu; Li, Feipeng; Chen, Ling

2018-08-01

The road traffic has become one of the main sources of urban pollution and could directly affect roadside soils. To understand the level of contamination and potential sources of trace metals in roadside soils of Shanghai, 10 trace metals (Sb, Cr, Co, Ni, Cu, Cd, Pb, Hg, Mn and Zn) from two urban/rural roads (Hutai Road and Wunign-Caoan Road) were analyzed in this study. Antimony, Ni, Cu, Cd, Pb, Hg and Zn concentrations were higher than that of soil background values of Shanghai, whereas accumulation of Cr, Co and Mn were minimal. Significantly higher Sb, Cd, Pb contents were found in samples from urban areas than those from suburban area, suggesting the impact from urbanization. The concentrations of Sb and Cd in older road (Hutai) were higher than that in younger road (Wunign-Caoan). Multivariate statistical analysis revealed that Sb, Cu, Cd, Pb and Zn were mainly controlled by traffic activities (e.g. brake wear, tire wear, automobile exhaust) with high contamination levels found near traffic-intensive areas; Cr, Co, Ni and Mn derived primarily from soil parent materials; Hg was related to industrial activities. Besides, the enrichment of Sb, Cd, Cu, Pb and Zn showed a decreasing trend with distance to the road edges. According to the enrichment factors (EF s ), 78.5% of Sb, Cu, Cd, Pb and Zn were in moderate or significant pollution, indicating considerable traffic contribution. In particular, recently introduced in automotive technology, accumulation of Sb has been recognized in 42.9% samples of both roads. The accumulation of these traffic-derived metals causes potential negative impact to human health and ecological environment and should be concerned, especially the emerging trace elements like Sb. Copyright © 2018 Elsevier B.V. All rights reserved.

Microstructure and property of diamond-like carbon films with Al and Cr co-doping deposited using a hybrid beams system

NASA Astrophysics Data System (ADS)

Dai, Wei; Liu, Jingmao; Geng, Dongsen; Guo, Peng; Zheng, Jun; Wang, Qimin

2016-12-01

DLC films with weak carbide former Al and carbide former Cr co-doping (Al:Cr-DLC) were deposited by a hybrid beams system comprising an anode-layer linear ion beam source (LIS) and high power impulse magnetron sputtering using a gas mixture of C2H2 and Ar as the precursor. The doped Al and Cr contents were controlled via adjusting the C2H2 fraction in the gas mixture. The composition, microstructure, compressive stress, mechanical properties and tribological behaviors of the Al:Cr-DLC films were researched carefully using X-ray photoelectron spectroscopy, transmission electron microscopy, Raman spectroscopy, stress-tester, nanoindentation and ball-on-plate tribometer as function of the C2H2 fraction. The results show that the Al and Cr contents in the films increased continuously as the C2H2 fraction decreased. The doped Cr atoms preferred to bond with the carbon while the Al atoms mainly existed in metallic state. Structure modulation with alternate multilayer consisted of Al-poor DLC layer and Al-rich DLC layer was found in the films. Those periodic Al-rich DLC layers can effectively release the residual stress of the films. On the other hand, the formation of the carbide component due to Cr incorporation can help to increase the film hardness. Accordingly, the residual stress of the DLC films can be reduced without sacrificing the film hardness though co-doping Al and Cr atoms. Furthermore, it was found that the periodic Al-rich layer can greatly improve the elastic resilience of the DLC films and thus decreases the film friction coefficient and wear rate significantly. However, the existence of the carbide component would cause abrasive wear and thus deteriorate the wear performance of the films.

Structural, magnetic and phonon properties of Cr(III)-doped perovskite metal formate framework [(CH{sub 3}){sub 2}NH{sub 2}][Mn(HCOO){sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl; Gągor, Anna; Hermanowicz, Krzysztof

2016-05-15

We have incorporated Cr(III) into [(CH{sub 3}){sub 2}NH{sub 2}][Mn(HCOO){sub 3}] (DMMn) multiferroic metal organic framework (MOF). The highest concentration of Cr(III) in the synthesized samples reached 15.9 mol%. The obtained samples were characterized by powder and single-crystal X-ray diffraction, DSC, magnetic susceptibility, dielectric, EPR, Raman and IR methods. These methods and the performed chemical analysis revealed that electrical charge neutrality after substitution of Cr(III) for Mn(II) is maintained by partial replacement of dimethylammonium (DMA{sup +}) cations by neutral HCOOH molecules. These changes in the chemical composition are responsible for weakening of the hydrogen bonds and decreased flexibility of the framework.more » This in turn leads to lowering of the ferroelectric phase transition temperature, observed around 185 K for undoped DMMn and around 155 K for the sample containing 3.1 mol% of Cr(III), and lack of macroscopic phase transition for the samples with Cr(III) content of 8.2 and 15.9 mol %. Another interesting effect observed for the studied samples is pronounced strengthening of the weak ferromagnetism of in Cr(III)-doped samples, associated with slight decrease of the ferromagnetic ordering temperature from 8.5 K for DMMn to 7.0 K for the sample with 15.9 mol % Cr(III) content. - Graphical abstract: Incorporation of Cr(III) into [(CH3)2NH2[Mn(HCOO)3] framework increases the magnetization. - Highlights: • Chromium(III) substitutes for Mn(II) in the studied MOF. • Charge neutrality is maintained by replacing DMA{sup +} cations by neutral HCOOH molecules. • Compounds with 8.2 and 15.9% of Cr(III) show no phase transition above 100 K. • Doping with Cr(III) increases magnetization.« less

Compositional and isotopic heterogeneities in the Neo-Tethyan upper mantle recorded by coexisting Al-rich and Cr-rich chromitites in the Purang peridotite massif, SW Tibet (China)

NASA Astrophysics Data System (ADS)

Xiong, Fahui; Yang, Jingsui; Xu, Xiangzhen; Kapsiotis, Argyrios; Hao, Xiaolin; Liu, Zhao

2018-06-01

The Purang harzburgite massif in SW Tibet (China) hosts abundant chrome ore deposits. Ores consist of 20 to >95% modal chromian spinel (Cr-spinel) with mylonitic fabric in imbricate shaped pods. The composition of Cr-spinel in these ores ranges from Al-rich [Cr#Sp or Cr/(Cr + Al) × 100 = 47.60-57.56] to Cr-rich (Cr#Sp: 62.55-79.57). Bulk platinum-group element (PGE) contents of chromitites are also highly variable ranging from 17.5 ppb to ∼2.5 ppm. Both metallurgical and refractory chromitites show a general enrichment in the IPGE (Os, Ir and Ru) with respect to the PPGE (Rh, Pt and Pd), resulting mostly in right-sloping primitive mantle (PM)-normalized PGE profiles. The platinum-group mineral (PGM) assemblages of both chromitite types are dominated by heterogeneously distributed, euhedral Os-bearing laurite inclusions in Cr-spinel. The Purang chromitites have quite inhomogeneous 187Os/188Os ratios (0.12289-0.13194) that are within the range of those reported for mantle-hosted chromitites from other peridotite massifs. Geochemical calculations demonstrate that the parental melts of high-Cr chromitites were boninitic, whereas those of high-Al chromitites had an arc-type tholeiitic affinity. Chromite crystallization was most likely stimulated by changes in magma compositions due to melt-peridotite interaction, leading to the establishment of a heterogeneous physicochemical environment during the early crystallization of the PGM. The highly variable PGE contents, inhomogeneous Os-isotopic compositions and varying Cr#Sp ratios of these chromitites imply a polygenetic origin for them from spatially distinct melt inputs. The generally low γOs values (<1) of chromitites indicate that their parental melts originated within different sections of a heterogeneously depleted mantle source region. These melts were most likely produced in the mantle wedge above a downgoing lithospheric slab.

Effects of Dietary Chromium Methionine on Growth Performance, Carcass Composition, Meat Colour and Expression of the Colour-related Gene Myoglobin of Growing-finishing Pigs

PubMed Central

Li, Y. S.; Zhu, N. H.; Niu, P. P.; Shi, F. X.; Hughes, C. L.; Tian, G. X.; Huang, R. H.

2013-01-01

To investigate the effect of dietary chromium (Cr) as Cr methionine (CrMet) on growth performance, carcass traits, pork quality, meat colour and expression of meat colour-related genes in growing-finishing pigs, 189 crossbred Duroc×(Landrace×Yorkshire) growing-finishing pigs (male, castrated, average initial BW 74.58±1.52 kg) were selected and randomly allocated into four groups. Dietary treatments per kg of feed were as follows: 0 (CT), 0.3 mg/kg (T1), 0.6 mg/kg (T2) and 0.9 mg/kg (T3) Cr (in the form of CrMet; as-fed basis), and each treatment was replicated five times with 8 to 10 pigs per replicate pen. During the 28 d of the experiment, both the ADG and the ADFI increased linearly (p<0.05) as the level of dietary Cr increased. The F/G ratio decreased linearly (p<0.05). As dietary Cr increased, loin muscle areas (linear, p = 0.013) and average backfat thickness (linear, p = 0.072) decreased. Shear force (linear, p = 0.070) and Commission Internationale de I’Éclairage (CIE) redness (quadratic, p = 0.028) were increased. In addition, CIE Lightness (quadratic, p = 0.053) were decreased as dietary Cr increased. As dietary Cr increased, total myglobin (Mb) content (quadratic, p = 0.015) and the mb mRNA levels (quadratic, p = 0.046) in longissimus muscles of pigs were up-regulated. In conclusion, supplementation of dietary Cr improved growth and meat colour, but increased shear force and decreased IMF reduced palatability of longissimus muscles. Moreover, the increasing total Mb content and mb mRNA levels indicated that CrMet dietary supplementation may improve meat colour via up-regulating expression of the mb gene. PMID:25049881

Comparison of the corrosion behavior of austenitic and ferritic/martensitic steels exposed to static liquid Pb Bi at 450 and 550 °C

NASA Astrophysics Data System (ADS)

Kurata, Y.; Futakawa, M.; Saito, S.

2005-08-01

Static corrosion tests of various steels were conducted in oxygen-saturated liquid Pb-Bi eutectic at 450 °C and 550 °C for 3000 h to study the effects of temperature and alloying elements on corrosion behavior in liquid Pb-Bi. Corrosion depth decreases at 450 °C with increasing Cr content in steels regardless of ferritic/martensitic steels or austenitic steels. Appreciable dissolution of Ni and Cr does not occur in the three austenitic steels at 450 °C. Corrosion depth of ferritic/martensitic steels also decreases at 550 °C with increasing Cr content in steels whereas corrosion depth of austenitic steels, JPCA and 316SS becomes larger due to ferritization caused by dissolution of Ni at 550 °C than that of ferritic/martensitic steels. An austenitic stainless steel containing about 5%Si exhibits fine corrosion resistance at 550 °C because the protective Si oxide film is formed and prevents dissolution of Ni and Cr.

Cr6+-containing phases in the system CaO-Al2O3-CrO42--H2O at 23 °C

NASA Astrophysics Data System (ADS)

Pöllmann, Herbert; Auer, Stephan

2012-01-01

Synthesis and investigation of lamellar calcium aluminium hydroxy salts was performed to study the incorporation of chromate ions in the interlayer of lamellar calcium aluminium hydroxy salts. Different AFm-phases (calcium aluminate hydrate with alumina, ferric oxide, mono-anion phase) containing chromate were synthesized. These AFm-phases belong to the group of layered double hydroxides (LDHs). 3CaO·Al2O3·CaCrO4·nH2O and C3A·1/2Ca(OH)2·1/2CaCrO4·12H2O were obtained as pure phases and their different distinct interlayer water contents and properties determined. Solid solution of chromate-containing phases and tetracalcium-aluminate-hydrate (TCAH) were studied. The uptake of chromate into TCAH from solutions was proven. Chromate contents in solution decrease to <0.2 mg/l.

Effects of wastewater irrigation on chemical and physical properties of Petroselinum crispum.

PubMed

Keser, Gonca; Buyuk, Gokhan

2012-06-01

The present study was carried out to assess the impact of wastewater on parsley (Petroselinum crispum). The parameters determined for soil were pH, electrical conductivity (EC), soil organic matter (SOM), nutrient elements (Ca, Mg, Na, K, Mn, Cu, Zn, and Fe), and heavy metals (Cd, Cr, Ni, and Pb), while the parameters determined for the plant included pigment content, dry matter, nutrient element, and heavy metals. SOM, EC, and clay contents were higher, and pH was slightly acidic in soil treated with wastewater compared to control soil. The enrichment factors (EF) of the nutrient elements in contaminated soil are in the sequence of Na (2) > Ca (1.32) > Mn = Mg (1.17) > Cu (1.11) > Zn (1.08) > Fe (1.07) > K (0.93), while EF in parsley are Na (6.63) > Ca (1.60) > Mg (1.34) > Zn (1.15) > Fe (0.95) > Cu = K (0.90) > Mn (0.85). Application of wastewater significantly decreased dry matter, while photosynthetic pigment content increased in parsley. The enrichment of the heavy metals is in the sequence: Cd (1.142) > Pb (1.131) > Ni (1.112) > Cr (1.095). P. crispum shows a high transfer factor (TF > 1) for Cd signifying a high mobility of Cd from soil to plant. Thus, although the wastewater irrigation in parsley production aims to produce socioeconomic benefits, study results indicated that municipal wastewater is not suitable for irrigation of parsley because it has negative effects on plant and causes heavy metal accumulation.

Comparative Study on Compositions and Functional Properties of Porcine, Chicken and Duck Blood

PubMed Central

2017-01-01

Hematological, chemical and functional characteristics of porcine, chicken and duck blood were evaluated. A porcine blood sample showed the most abundant red blood cell, hemoglobin concentration, packed cell volume and plasma protein content as well as its freeze-dried blood possessed the highest contents of protein, fat, Cu and Cr with the highest percentage of heme iron (p<0.05). Unlike porcine blood, chicken blood showed a well balance in some essential amino acids, specifically for a higher isoleucine content (p<0.05). Furthermore, it possessed the highest contents of carbohydrate, Zn and non-heme iron (p<0.05). The most rapid response to form a strong gel, especially at 70°C and 80°C, was found in chicken blood, followed by duck and porcine blood, respectively. The result of emulsion activity index (EAI) and emulsion stability index (ESI) at the low protein concentration indicated that chicken blood had the most superior emulsion properties (p<0.05). Regarding duck blood, it exhibited the highest content of Mg and Mn (p<0.05). Moreover, duck blood had similar foaming properties to porcine blood in which they showed higher values than chicken blood (p<0.05). Specific characteristics of blood were therefore diminished by animal species in which this information could be used as food supplementation or product development based on their potential applications. PMID:28515647

Response of Cr and Cr-Al coatings on Zircaloy-2 to high temperature steam

NASA Astrophysics Data System (ADS)

Zhong, Weicheng; Mouche, Peter A.; Heuser, Brent J.

2018-01-01

The oxidation behavior of chromium (Cr) and chromium-aluminum (CrAl) coatings with various compositions deposited on Zircaloy-2 to 700 °C high-temperature steam (HTS) exposure has been investigated. CrAl coatings with higher Al compositions demonstrate lower oxidation weight gain. A layer of γ-alumina developed on the CrAl coatings with Al composition over 43 at%, while Al2O3 and Cr2O3 developed on CrAl coatings with Al composition below 33 at%. Oxidation of Zircaloy-2 substrate was inhibited by the 1um coatings to 20 h HTS exposure. Coating constituent elements diffused into the substrate and formed intermetallic phases with the Zircaloy substrate. Thicker layers of intermetallic phases developed on the coatings with higher Al composition. The intermetallic phases included Fe and Ni, indicating the dissolution of second phase particles (SPPs) during HTS exposure.

Diets containing leguminous seeds influence chromium content in the rat femur bone.

PubMed

Gralak, M A; Leontowicz, H; Leontowicz, M; Debski, B

2002-01-01

Leguminous seeds contain a lot of antinutritional factors (ANFs) such as protease inhibitors, lectins and condensed tannins which can affect bioavailability of nutrients. Detrimental effect of protease inhibitors can be decreased by sulphur amino acids addition. Moreover, most of the leguminous ANFs are thermolabile. Hence, legumes tested in our study were extruded and/or diets were supplemented with methionine and cystine (0.15% + 0.15%). The present experiment was performed for 28 days on 90 Wistar rats divided into nine feeding groups. Semipurified diets (10% casein) were supplemented (10%), except the control one, with soybean (S) or faba bean (F), raw (R) or extruded (E), with addition of sulphur amino acids (SAA) or without them. The Cr concentration was determined in the femur bone. Total feed intake during whole trial widely varied among the groups and was the lowest in SR (289 g) and FR (294 g) groups. There was no correlation between feed intake and Cr content in the femur bone. Generally, 10% soybean in the diet decreased Cr concentration in the bones, and faba bean increased it. The SAA addition to diets generally increased femur Cr content. However, there was a significant interaction between SAA supplementation and extrusion of faba bean, hence, the effect of their combination was unclear.

Effects of cooling time and alloying elements on the microstructure of the gleeble-simulated heat-affected zone of 22% Cr duplex stainless steels

NASA Astrophysics Data System (ADS)

Hsieh, Rong-Iuan; Liou, Horng-Yih; Pan, Yeong-Tsuen

2001-10-01

The effects of austenite stabilizers, such as nitrogen, nickel, and manganese, and cooling time on the microstructure of the Gleeble simulated heat-affected zone (HAZ) of 22% Cr duplex stainless steels were investigated. The submerged are welding was performed for comparison purposes. Optical microscopy (OM) and transmission electron microscopy (TEM) were used for microscopic studies. The amount of Cr2N precipitates in the simulated HAZ was determined using the potentiostatic electrolysis method. The experimental results indicate that an increase in the nitrogen and nickel contents raised the δ to transformation temperature and also markedly increased the amount of austenite in the HAZ. The lengthened cooling time promotes the reformation of austenite. An increase in the austenite content reduces the supersaturation of nitrogen in ferrite matrix as well as the precipitation tendency of Cr2N. The optimum cooling time from 800 to 500 °C (Δ t 8/5) obtained from the Gleeble simulation is between 30 and 60 s, which ensures the austenite content in HAZ not falling below 25% and superior pitting and stress corrosion cracking resistance for the steels. The effect of manganese on the formation of austenite can be negligible.

The Effect of Carbonaceous Reductant Selection on Chromite Pre-reduction

NASA Astrophysics Data System (ADS)

Kleynhans, E. L. J.; Beukes, J. P.; Van Zyl, P. G.; Bunt, J. R.; Nkosi, N. S. B.; Venter, M.

2017-04-01

Ferrochrome (FeCr) production is an energy-intensive process. Currently, the pelletized chromite pre-reduction process, also referred to as solid-state reduction of chromite, is most likely the FeCr production process with the lowest specific electricity consumption, i.e., MWh/t FeCr produced. In this study, the effects of carbonaceous reductant selection on chromite pre-reduction and cured pellet strength were investigated. Multiple linear regression analysis was employed to evaluate the effect of reductant characteristics on the aforementioned two parameters. This yielded mathematical solutions that can be used by FeCr producers to select reductants more optimally in future. Additionally, the results indicated that hydrogen (H)- (24 pct) and volatile content (45.8 pct) were the most significant contributors for predicting variance in pre-reduction and compressive strength, respectively. The role of H within this context is postulated to be linked to the ability of a reductant to release H that can induce reduction. Therefore, contrary to the current operational selection criteria, the authors believe that thermally untreated reductants ( e.g., anthracite, as opposed to coke or char), with volatile contents close to the currently applied specification (to ensure pellet strength), would be optimal, since it would maximize H content that would enhance pre-reduction.

Reduction of Health Risks Due to Chromium(VI)Using Mesquite: A Potential Cr Phytoremediator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardea-Torresdey, Jorge L.; Aldrich, Mary V.; Peralta-Videa, Jose R.

Chromium is a transition metal extensively used in industry. Cr mining and industrial operations account for chromium wastes at Superfund sites in the United States. A study was performed to investigate the possibility of using mesquite (Prosopis spp.), which is an indigenous desert plant species, to remove Cr from contaminated sites. In this study, mesquite plants were grown in an agar-based medium containing 75 mg L-1 and 125 mg L-1 of Cr(VI). The Cr content of leaf tissue (992 mg kg-1 of dry weight, from 125 mg L-1 of Cr(VI)) indicated that mesquite could be classified as a chromium hyperaccumulator.more » X-ray absorption spectroscopy (XAS) studies performed to experimental samples showed that mesquite roots absorbed some of the supplied Cr(VI). However, the data analyses of plant tissues demonstrated that the absorbed Cr(VI) was fully reduced to Cr(III) in the leaf tissue.« less

Experience-Dependent Synaptic Plasticity in V1 Occurs without Microglial CX3CR1

PubMed Central

Stevens, Beth

2017-01-01

Brief monocular deprivation (MD) shifts ocular dominance and reduces the density of thalamic synapses in layer 4 of the mouse primary visual cortex (V1). We found that microglial lysosome content is also increased as a result of MD. Previous studies have shown that the microglial fractalkine receptor CX3CR1 is involved in synaptic development and hippocampal plasticity. We therefore tested the hypothesis that neuron-to-microglial communication via CX3CR1 is an essential component of visual cortical development and plasticity in male mice. Our data show that CX3CR1 is not required for normal development of V1 responses to visual stimulation, multiple forms of experience-dependent plasticity, or the synapse loss that accompanies MD in layer 4. By ruling out an essential role for fractalkine signaling, our study narrows the search for understanding how microglia respond to active synapse modification in the visual cortex. SIGNIFICANCE STATEMENT Microglia in the visual cortex respond to monocular deprivation with increased lysosome content, but signaling through the fractalkine receptor CX3CR1 is not an essential component in the mechanisms of visual cortical development or experience-dependent synaptic plasticity. PMID:28951447

CR chondrites: Shock, aqueous alteration and terrestrial weathering

NASA Astrophysics Data System (ADS)

Abreu, N. M.

2012-12-01

CR chondrite are a group asteroidal meteorites, whose importance lies in the exotic organic and presolar material [1] found in its most pristine members and in the broad range of alteration features represented in the remaining specimens in this group [2]. This FE-SEM, EMPA, FIB/TEM study takes advantage of the CR's mineralogical diversity to define different trends of secondary alteration, by comparing the CR3s to the Antarctic CRs: MIL 07525, MIL 07513, GRA 06100, LAP 04516, GRO 03116, GRO 95577, and EET 96259. Collisions and subsequent annealing have affected MIL 07513, GRA 06100, and GRO 03116. Shock stages are often assigned based on progressive changes in the textures of olivines and feldspars. However, the large olivines in shocked CRs do not appear to record these process. Opaques, on the other hand, preserve hallmark signatures of impacts, such as crystalline metal/sulfide veins. Opaque nodules in MIL 07513, GRA 06100, GRO 03116 consist of intergrowths of μm-sub μm FeNi-rich metal, kamacite, Fe-sulfides, Fe-oxides, nm-sized metallic Cu and CuFe (~85 wt.% Cu, 14 wt.% Fe ± < 1wt.% Co, Ni, S) alloys. MIL 07525, GRO 03116, EET 96259, LAP 04516, and GRO 95577 show increasing signs of aqueous alteration, such as increasing amounts of ordered phyllosilicates. Although most phyllosilicates are intergrowths of Fe-rich serpentine and saponite, LAP 04516 also contains large (μm-sized), interpenetrating, Fe-rich (cronstedtite-like) phyllosilicates packages with 14Å basal spacings, similar to those observed in CI chondrites by [3]. Heterogeneously interspersed within phyllosilicates are amorphous Fe-rich silicates and small grains (<50nm) of Fe-rich sulfides, partly oxidized sulfides, and in LAP 04516, tochilinite. Tochilinite shows consistent enrichments in Si (~5 wt.%), suggesting that this meteorite has undergone similar pathways of aqueous alteration as CM chondrites [e.g., 4-5]. Despite the myriad of mineralogical changes triggered by secondary and tertiary process affecting the CRs, the relationship between the average S and Fe contents of matrices are good indicators of the alteration histories of these chondrites. The average S versus Fe contents of CR matrices follow a roughly linear trend. The most aqueously altered CRs (e.g., LAP 04516) have the lowest Fe and the highest S content. The matrices in shocked CRs, MIL 07513, GRA 06100, GRO 03116, have the lowest S content of the studied CRs. They are also the most Fe-rich. The CR3 chondrites fall somewhere in the middle of the S vs. Fe plot. Terrestrial weathering creates some scattering due to its contribution to the Fe-content of the matrix. If the precursor materials of the shocked CRs composi-tionally resemble CR3 chondrites, low S content of shocked CR matrices probably resulted from volatile losses driven by shock and annealing. Whereas increasing Fe-contents are probably linked to impact-driven hydrothermal mobilization of Fe from kamacite nodules. References: [1] Floss et al. 2009. Ap. J. 697: 1242-1255. [2] Abreu N. M. 2007. [3] Tomeoka K. & Buseck P. R. 1988. GCA 52: 1627-1640. [4] Tomeoka K. & Buseck P. R. 1985. GCA 49: 21-49-2163. [5] Rubin A. et al. 2007. GCA 71: 2361-2382. Acknowledgements: Funded by NNX11AH10G grant and conducted at Penn State and ARES-JSC. Meteorite kindly pro-vided by the JSC Antarctic meteorite curators.

Resting-state global functional connectivity as a biomarker of cognitive reserve in mild cognitive impairment.

PubMed

Franzmeier, N; Caballero, M Á Araque; Taylor, A N W; Simon-Vermot, L; Buerger, K; Ertl-Wagner, B; Mueller, C; Catak, C; Janowitz, D; Baykara, E; Gesierich, B; Duering, M; Ewers, M

2017-04-01

Cognitive reserve (CR) shows protective effects in Alzheimer's disease (AD) and reduces the risk of dementia. Despite the clinical significance of CR, a clinically useful diagnostic biomarker of brain changes underlying CR in AD is not available yet. Our aim was to develop a fully-automated approach applied to fMRI to produce a biomarker associated with CR in subjects at increased risk of AD. We computed resting-state global functional connectivity (GFC), i.e. the average connectivity strength, for each voxel within the cognitive control network, which may sustain CR due to its central role in higher cognitive function. In a training sample including 43 mild cognitive impairment (MCI) subjects and 24 healthy controls (HC), we found that MCI subjects with high CR (> median of years of education, CR+) showed increased frequency of high GFC values compared to MCI-CR- and HC. A summary index capturing such a surplus frequency of high GFC was computed (called GFC reserve (GFC-R) index). GFC-R discriminated MCI-CR+ vs. MCI-CR-, with the area under the ROC = 0.84. Cross-validation in an independently recruited test sample of 23 MCI subjects showed that higher levels of the GFC-R index predicted higher years of education and an alternative questionnaire-based proxy of CR, controlled for memory performance, gray matter of the cognitive control network, white matter hyperintensities, age, and gender. In conclusion, the GFC-R index that captures GFC changes within the cognitive control network provides a biomarker candidate of functional brain changes of CR in patients at increased risk of AD.

High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

NASA Astrophysics Data System (ADS)

Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

2017-09-01

A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

Influence of trimethylsilane flow on the microstructure, mechanical and tribological properties of CrSiCN coatings in water lubrication

NASA Astrophysics Data System (ADS)

Wu, Zhiwei; Zhou, Fei; Wang, Qianzhi; Zhou, Zhifeng; Yan, Jiwang; Li, Lawrence Kwok-Yan

2015-11-01

CrSiCN coatings with different silicon and carbon contents were deposited on silicon wafers and 316L stainless steels using unbalanced magnetron sputtering via adjusting trimethylsilane (TMS) flow, and their microstructure and mechanical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy(SEM), X-ray photoelectrons spectroscopy(XPS) and nano-indenter, respectively. The tribological properties of CrSiCN coatings sliding against SiC balls in water were investigated using ball-on-disk tribometer. The results showed that the CrSiCN coatings had fine composite microstructure consisting of nanocrystallites of Cr(C, N) crystal and amorphous phases such as a-Si3N4 and a-C(a-CNx). The typical columnar structures changed from fine cluster to coarse ones when the Si content was beyond 3.4 at.%. With an increase in the TMS flow, the hardness and Young's modulus of Corsican coatings all first increased, and then rapidly decreased, but the compressive stress in the coatings varied in the range of 2.8-4.8 GPa. When the TMS flow was 10 sccm, the CrSiCN coatings exhibited the highest hardness of 21.3 GPa and the lowest friction coefficient (0.11) and wear rate (8.4 × 10-8 mm3/N m). But when the TMS flow was beyond 15 sccm, the tribological properties of CrSiCN coatings in water became poor.

Supplementation with chromium picolinate recovers renal Cr concentration and improves carbohydrate metabolism and renal function in type 2 diabetic mice.

PubMed

Mita, Yukiko; Ishihara, Kengo; Fukuchi, Yoshiko; Fukuya, Yoko; Yasumoto, Kyoden

2005-01-01

To study the preventive effect of supplemented chromium picolinate (CrPic) on the development of diabetic nephropathy in mice, we analyzed the effects of CrPic supplementation on renal function and concentrations of serum glucose and tissue chromium (Cr). In experiment 1, male KK-Ay obese diabetic mice were fed either a control diet (control) or a diet supplemented with 2 mg/kg diet (Cr2) or 10 mg/kg diet (Cr10) of Cr for 12 wk. Cr10 significantly ameliorated hyperglycemia after a glucose load, creatinine clearance rates, and urinary microalbumin levels (p<0.05). In experiment 2, the Cr10 diet was fed to male KK-Ay obese diabetic mice and C57BL nondiabetic mice for 4 wk. The CrPic diet reduced urinary albumin excretion in the diabetic mice (p<0.05). Inductively coupled plasma-mass spectrometry analysis revealed that the renal Cr content and the recovery of renal Cr concentration after Cr supplementation were significantly lower in the diabetic mice than in the nondiabetic mice (p<0.01). These observations suggest that Cr supplementation of type 2 diabetic mice reduces the symptoms of hyperglycemia and improves the renal function by recovering renal Cr concentration.

Impact of heavy metals on photosynthetic pigment content in roadside plant communities

NASA Astrophysics Data System (ADS)

Popova, Elena

2017-11-01

The research is dedicated to the study of the impact of heavy metals (As, Cr, Cu, Mo, Ni, Pb, Sr, Zn) found in plant samples on photosynthetic pigments in anthropogenic roadside plant communities. In the process of research, the anthropogenic load intensity for the selected sites (1 < 6 < 5 < 4 < 2 < 3) was determined. The analysis of the results showed that the impact of heavy metals on photosynthetic pigment content depends not only on metal toxicity but also on its concentration. A high level was noted for Pb (7.2-10.6), Cr (2.6-4.5), As (0.1-0.9) and Sr (9.4-12.1) mg/kg. The inverse relation between the heavy metal and photosynthetic pigment concentrations was revealed. The research showed that the concentration of chlorophyll a, b and carotenoids changes depending on the growing conditions. Carotenoids are less vulnerable to the negative impact of heavy metals as compared to chlorophylls. A higher concentration of carotenoids is noted in stressing environment. On the one hand, it decreases stress effect; on the other hand, it performs a protective function by preventing destruction of chlorophyll molecules and other organic substances. The obtained data may be used to forecast dynamics of plant populations and communities in the polluted areas and to monitor conditions of natural ecosystems.

Behavior of toxic metals and radionuclides during molten salt oxidation of chlorinated plastics.

PubMed

Yang, Hee-Chul; Cho, Yong-Jun; Eun, Hee-Chul; Yoo, Jae-Hyung; Kim, Joon-Hyung

2004-01-01

Molten salt oxidation is one of the promising alternatives to incineration for chlorinated organics without the emission of chlorinated organic pollutants. This study investigated the behavior of three hazardous metals (Cd, Pb, and Cr) and four radioactive metal surrogates (Cs, Ce, Gd, and Sm) in the molten Na2CO3 oxidation reactor during the destruction of PVC plastics. In the tested temperature ranges (1143 1223K) and NaCl content (0-10%), the impact of temperature on the retention of cadmium and lead in the molten salt reactor was very small, but that of the NaCl content for their retention was relatively higher. The influence of NaCl accumulation was, however, proven to be practically negligible due to the low-temperature operating characteristics of the molten salt oxidation system. Neither temperature increase nor chlorine accumulation in the MSO reactor reduced the retention of Cr, Ce, Gd, and Sm. Over 99.98% of these metals remained in the reactor. The influence of the temperature on the cesium behavior is relatively large for a chlorine addition, however, over 99.7% of cesium remained in the reactor throughout the entire test. The experimental metal entrainment rate and the entrained metal particle size distribution agree well with the theoretical equilibrium metal distributions.

Modelling in vivo creatine/phosphocreatine in vitro reveals divergent adaptations in human muscle mitochondrial respiratory control by ADP after acute and chronic exercise.

PubMed

Ydfors, Mia; Hughes, Meghan C; Laham, Robert; Schlattner, Uwe; Norrbom, Jessica; Perry, Christopher G R

2016-06-01

Mitochondrial respiratory sensitivity to ADP is thought to influence muscle fitness and is partly regulated by cytosolic-mitochondrial diffusion of ADP or phosphate shuttling via creatine/phosphocreatine (Cr/PCr) through mitochondrial creatine kinase (mtCK). Previous measurements of respiration in vitro with Cr (saturate mtCK) or without (ADP/ATP diffusion) show mixed responses of ADP sensitivity following acute exercise vs. less sensitivity after chronic exercise. In human muscle, modelling in vivo 'exercising' [Cr:PCr] during in vitro assessments revealed novel responses to exercise that differ from detections with or without Cr (±Cr). Acute exercise increased ADP sensitivity when measured without Cr but had no effect ±Cr or with +Cr:PCr, whereas chronic exercise increased sensitivity ±Cr but lowered sensitivity with +Cr:PCr despite increased markers of mitochondrial oxidative capacity. Controlling in vivo conditions during in vitro respiratory assessments reveals responses to exercise that differ from typical ±Cr comparisons and challenges our understanding of how exercise improves metabolic control in human muscle. Mitochondrial respiratory control by ADP (Kmapp ) is viewed as a critical regulator of muscle energy homeostasis. However, acute exercise increases, decreases or has no effect on Kmapp in human muscle, whereas chronic exercise surprisingly decreases sensitivity despite greater mitochondrial content. We hypothesized that modelling in vivo mitochondrial creatine kinase (mtCK)-dependent phosphate-shuttling conditions in vitro would reveal increased sensitivity (lower Kmapp ) after acute and chronic exercise. The Kmapp was determined in vitro with 20 mm Cr (+Cr), 0 mm Cr (-Cr) or 'in vivo exercising' 20 mm Cr/2.4 mm PCr (Cr:PCr) on vastus lateralis biopsies sampled from 11 men before, immediately after and 3 h after exercise on the first, fifth and ninth sessions over 3 weeks. Dynamic responses to acute exercise occurred throughout training, whereby the first session did not change Kmapp with in vivo Cr:PCr despite increases in -Cr. The fifth session decreased sensitivity with Cr:PCr or +Cr despite no change in -Cr. Chronic exercise increased sensitivity ±Cr in association with increased electron transport chain content (+33-62% complexes I-V), supporting classic proposals that link increased sensitivity to oxidative capacity. However, in vivo Cr:PCr reveals a perplexing decreased sensitivity, contrasting the increases seen ±Cr. Functional responses occurred without changes in fibre type or proteins regulating mitochondrial-cytosolic energy exchange (mtCK, VDAC and ANT). Despite the dynamic responses seen with ±Cr, modelling in vivo phosphate-shuttling conditions in vitro reveals that ADP sensitivity is unchanged after high-intensity exercise and is decreased after training. These findings challenge our understanding of how exercise regulates skeletal muscle energy homeostasis. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

[Gas exchange features of Ambrosia artemisiifolia leaves and fruits and their correlations with soil heavy metals].

PubMed

Zu, Yuangang; Wang, Wenjie; Chen, Huafeng; Yang, Fengjian; Zhang, Zhonghua

2006-12-01

Ambrosia artemisiifolia can survive well in the habitats of heavy human disturbance and partial soil pollution. Weather its photosynthetic features benefit their survival is worthwhile to concern. With a refuse dump in Changchun City (43 degrees 50'N, 125 degrees 23'E) as study site, this paper analyzed the contents of soil Cu, Pb, Zn, Mn, Cr, Co, Ni, Cd, As, Sb and Hg at ten plots, and measured in situ the gas exchange in A. artemisiifolia leaves and young fruits. The results showed that the study site was slightly contaminated by Ni, but the contents of other soil heavy metals were approached to or substantially lower than their threshold values. The net photosynthetic rate of leaves ranged from 1.88 to 9.41 micromol x m(-2) x s(-1), while that of young fruits could be up to 2. 81 micromol x m(-2) s(-1). Averagely, the respiration rate, stomatal conductance, photosynthetic rate, and water utilization efficiency of leaves were 1.81 micromol x m(-2) x s(-1), 75.7 mmol x m(-2) x s(-1), 6.05 micromol x m(-2) x s(-1), and 4.72 micromol CO2 x mmol(-1) H2O, being 5.26, 0.64, 1.31 and 1.69 times as much as those of young fruits, respectively, indicating that the respiratory and photosynthetic capacities and water use efficiency of A. artemisiifolia young fruits were equivalent to or higher than those of its leaves. Many test heavy metals, such as Cu, Pb, Zn, Cd, As, Sb and Hg, had no significant effects on the gas exchange features of leaves and fruits, but there were significant correlations of Ni and Cr with the stomatal conductance and water use efficiency of leaves and young fruits, Cr with the gross photosynthesis of leaves, and As with the stomatal conductance of young fruits, suggesting that a majority of test soil heavy metals had no direct effects on the gas exchange in A. artemisiifolia leaves and fruits, but soil Ni, Cr and As with the contents approached to or substantially lower than the threshold values could affect the gas exchange features of A. artemisiifolia.

Study of TLIPSS formation on different metals and alloys and their selective etching

NASA Astrophysics Data System (ADS)

Dostovalov, Alexandr V.; Korolkov, Victor P.; Terentiev, Vadim S.; Okotrub, Konstantin A.; Dultsev, Fedor N.; Nemykin, Anton; Babin, Sergey A.

2017-02-01

Experimental investigation of thermochemical laser-induced periodic surface structures (TLIPSS) formation on metal films (Ti, Cr, Ni, NiCr) at different processing conditions is presented. The hypothesis that the TLIPSS formation depends significantly on parabolic rate constant for oxide thin film growth is discussed. Evidently, low value of this parameter for Ni is the reason of TLIPSS absence on Ni and NiCr film with low Cr content. The effect of simultaneous ablative (with period ≍λ) and thermochemical (with period ≍λ) LIPSS formation was observed. The formation of structures after TLIPSS selective etching was demonstrated.

EPR study of chromium-doped forsterite crystals: Cr3+( M1) with associated trivalent ions Al3+ and Sc3+

NASA Astrophysics Data System (ADS)

Ryabov, I. D.

2012-10-01

Electron paramagnetic resonance (EPR) study of single crystals of forsterite co-doped with chromium and scandium has revealed, apart from the known paramagnetic centers Cr3+( M1) and Cr3+( M1)- V_{{{{Mg}}^{2 + } }} ( M2) (Ryabov in Phys Chem Miner 38:177-184, 2011), a new center Cr3+( M1)- V_{{{{Mg}}^{2 + } }} ( M2)-Sc3+ formed by a Cr3+ ion substituting for Mg2+ at the M1 structural position with a nearest-neighbor Mg2+ vacancy at the M2 position and a Sc3+ ion presumably at the nearest-neighbor M1 position. For this center, the conventional zero-field splitting parameters D and E and the principal g values have been determined as follows: D = 33,172(29) MHz, E = 8,482(13) MHz, g = [1.9808(2), 1.9778(2), 1.9739(2)]. The center has been compared with the known ion pair Cr3+( M1)-Al3+ (Bershov et al. in Phys Chem Miner 9:95-101, 1983), for which the refined EPR data have been obtained. Based on these data, the known sharp M1″ line at 13,967 cm-1 (with the splitting of 1.8 cm-1), observed in low-temperature luminescence spectra of chromium-doped forsterite crystals (Glynn et al. in J Lumin 48, 49:541-544, 1991), has been ascribed to the Cr3+( M1)-Al3+ center. It has been found that the concentration of the new center increases from 0 up to 4.4 × 1015 mg-1, whereas that of the Cr3+( M1) and Cr3+( M1)- V_{{{{Mg}}^{2 + } }} ( M2) centers quickly decreases from 7.4 × 1015 mg-1 down to 3 × 1015 mg-1 and from 2.7 × 1015 mg-1 down to 0.5 × 1015 mg-1, i.e., by a factor of 2.5 and 5.4, respectively, with an increase of the Sc content from 0 up to 0.22 wt % (at the same Cr content 0.25 wt %) in the melt. When the Sc content exceeds that of Cr, the concentration of the new center decreases most likely due to the formation of the Sc3+( M1)- V_{{{{Mg}}^{2 + } }} ( M2)-Sc3+ complex instead of the Cr3+( M1)- V_{{{{Mg}}^{2 + } }} ( M2)-Sc3+ center. The formation of such ordered neutral complex is in agreement with the experimental results, concerning the incorporation of Sc into olivine, recently obtained by Grant and Wood (Geochim Cosmochim Acta 74:2412-2428, 2010).

First principles calculation of elastic and magnetic properties of Cr-based full-Heusler alloys

NASA Astrophysics Data System (ADS)

Aly, Samy H.; Shabara, Reham M.

2014-06-01

We present an ab-initio study of the elastic and magnetic properties of Cr-based full-Heusler alloys within the first-principles density functional theory. The lattice constant, magnetic moment, bulk modulus and density of states are calculated using the full-potential nonorthogonal local-orbital minimum basis (FPLO) code in the Generalized Gradient Approximation (GGA) scheme. Only the two alloys Co2CrSi and Fe2CrSi are half-metallic with energy gaps of 0.88 and 0.55 eV in the spin-down channel respectively. We have predicted the metallicity state for Fe2CrSb, Ni2CrIn, Cu2CrIn, and Cu2CrSi alloys. Fe2CrSb shows a strong pressure dependent, e.g. exhibits metallicity at zero pressure and turns into a half-metal at P≥10 GPa. The total and partial magnetic moments of these alloys were studied under higher pressure, e.g. in Co2CrIn, the total magnetic moment is almost unchanged under higher pressure up to 500 GPa.

Influence of Substrate Heating and Nitrogen Flow on the Composition, Morphological and Mechanical Properties of SiNx Coatings Aimed for Joint Replacements

PubMed Central

Skjöldebrand, Charlotte; Schmidt, Susann; Vuong, Vicky; Pettersson, Maria; Grandfield, Kathryn; Högberg, Hans; Engqvist, Håkan; Persson, Cecilia

2017-01-01

Silicon nitride (SiNx) coatings are promising for joint replacement applications due to their high wear resistance and biocompatibility. For such coatings, a higher nitrogen content, obtained through an increased nitrogen gas supply, has been found to be beneficial in terms of a decreased dissolution rate of the coatings. The substrate temperature has also been found to affect the composition as well as the microstructure of similar coatings. The aim of this study was to investigate the effect of the substrate temperature and nitrogen flow on the coating composition, microstructure and mechanical properties. SiNx coatings were deposited onto CoCrMo discs using reactive high power impulse magnetron sputtering. During deposition, the substrate temperatures were set to 200 °C, 350 °C or 430 °C, with nitrogen-to-argon flow ratios of 0.06, 0.17 or 0.30. Scanning and transmission electron spectroscopy revealed that the coatings were homogenous and amorphous. The coatings displayed a nitrogen content of 23–48 at.% (X-ray photoelectron spectroscopy). The surface roughness was similar to uncoated CoCrMo (p = 0.25) (vertical scanning interferometry). The hardness and Young’s modulus, as determined from nanoindentation, scaled with the nitrogen content of the coatings, with the hardness ranging from 12 ± 1 GPa to 26 ± 2 GPa and the Young’s moduli ranging from 173 ± 8 GPa to 293 ± 18 GPa, when the nitrogen content increased from 23% to 48%. The low surface roughness and high nano-hardness are promising for applications exposed to wear, such as joint implants. PMID:28772532

Sandblasting and silica-coating of dental alloys: volume loss, morphology and changes in the surface composition.

PubMed

Kern, M; Thompson, V P

1993-05-01

Silica-coating alloys improves chemo-mechanical bonding. Sandblasting is recommended as pretreatment to thermal silica-coating or as part of a tribochemical silica-coating process. This study evaluated the effects of sandblasting and coating techniques on volume loss, surface morphology and compositional changes in noble (AuAgCu) and base alloys (NiCr and CoCr). Volume loss was statistically significantly higher in the noble as compared to the base alloys but does not seem to be critical for the clinical fit of restorations. Embedded alumina particles were found in all alloys after sandblasting and the alumina content increased to a range of 14 to 37 wt% as measured by EDS. Following tribochemical silica-coating, a layer of small silica particles remained on the surface, increasing the silica content to between 12 and 20 wt%. Ultrasonic cleaning removed loose alumina or silica particles from the surface, resulting in only slight decreases in alumina or silica contents, thus suggesting firm attachment of the major part of alumina and silica to the alloy surface. Clinically, ultrasonic cleaning of sandblasted and tribochemically silica-coated alloys might improve resin bonding as loose surface particles are removed without relevant changes in composition. Silica content following thermal silica-coating treatment increased only slightly from the sandblasted specimen. The silica layer employed by these silica-coating methods differs widely in both morphology and thickness. These results provide a basis for explanation of adhesive failure modes in bond strength tests which will possibly optimize resin bonding. Further research is needed to characterize the outermost surface layers after these treatments and the exact location of adhesive failures.

Generation of Ince-Gaussian beams in highly efficient, nanosecond Cr, Nd:YAG microchip lasers

NASA Astrophysics Data System (ADS)

Dong, J.; Ma, J.; Ren, Y. Y.; Xu, G. Z.; Kaminskii, A. A.

2013-08-01

Direct generation of higher-order Ince-Gaussian (IG) beams from laser-diode end-pumped Cr, Nd:YAG self-Q-switched microchip lasers was achieved with high efficiency and high repetition rate. An average output power of over 2 W was obtained at an absorbed pump power of 8.2 W a corresponding optical-to-optical efficiency of 25% was achieved. Various IG modes with nanosecond pulse width and peak power of over 2 kW were obtained in laser-diode pumped Cr, Nd:YAG microchip lasers under different pump power levels by applying a tilted, large area pump beam. The effect of the inversion population distribution induced by the tilted pump beam and nonlinear absorption of Cr4+-ions for different pump power levels on the oscillation of higher-order IG modes in Cr, Nd:YAG microchip lasers is addressed. The higher-order IG mode oscillation has a great influence on the laser performance of Cr, Nd:YAG microchip lasers.

Magnetic properties and element concentrations in lichens exposed to airborne pollutants released during cement production.

PubMed

Paoli, Luca; Winkler, Aldo; Guttová, Anna; Sagnotti, Leonardo; Grassi, Alice; Lackovičová, Anna; Senko, Dušan; Loppi, Stefano

2017-05-01

The content of selected elements (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, S, Ti, V and Zn) was measured in samples of the lichen Evernia prunastri exposed for 30, 90 and 180 days around a cement mill, limestone and basalt quarries and urban and agricultural areas in SW Slovakia. Lichens transplanted around the investigated quarries and the cement mill rapidly (30 days) reflected the deposition of dust-associated elements, namely Ca (at the cement mill and the limestone quarry) and Fe, Ti and V (around the cement mill and the basalt quarry), and their content remained significantly higher throughout the whole period (30-180 days) with respect to the surrounding environment. Airborne pollutants (such as S) progressively increased in the study area from 30 to 180 days. The magnetic properties of lichen transplants exposed for 180 days have been characterized and compared with those of native lichens (Xanthoria parietina) and neighbouring bark, soil and rock samples, in order to test the suitability of native and transplanted samples as air pollution magnetic biomonitors. The magnetic mineralogy was homogeneous in all samples, with the exception of the samples from the basalt quarry. The transplants showed excellent correlations between the saturation remanent magnetization (Mrs) and the content of Fe. Native samples had a similar magnetic signature, but the values of the concentration-dependent magnetic parameters were up to two orders of magnitude higher, reflecting higher concentrations of magnetic particles. The concentrations of As, Ca and Cr in lichens correlated with Mrs values after neglecting the samples from the basalt quarry, which showed distinct magnetic properties, suggesting the cement mill as a likely source. Conversely, Ti and Mn were mostly (but not exclusively) associated with dust from the basalt quarry. It is suggested that the natural geological characteristics of the substrate may strongly affect the magnetic properties of lichen thalli. Taking this into account, the results of this study point out the suitability of lichens as air pollution magnetic biomonitors.

ESR spectrum of Cr(V) with 2,3-dioxynaphthalene in a liquid crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novosadov, N.A.; Mukhtarov, A.S.; Usmanov, Z.I.

1987-01-01

Research has previously been reported on the complex formed by Cr(V) with 2,3-dioxynaphthalene (I) in solution in DMFA. An open question remaining is the mutual orientation of the molecular symmetry axes and the magnetic ones. The authors give results on the complex formed by Cr(V) with I obtained by ESR in 4-methoxy-benzylidene-n-4'-butylaniline (MBBA). The ESR spectrum of Cr(V) with I in the nematic phase of MBBA is a strong line due to /sup 52/Cr with g = 1.978 and four weak lines due to /sup 53/Cr at the natural content with HFI constant a* = 11.8 x 10/sup -4/ T;more » when the MBBA is converted to the isotropic phase, the observed HFI constant from /sup 53/Cr increases to 18 x 10/sup -4/ T, while the g factor is unaltered.« less

Cation distribution and optical properties of Cr-doped MgGa2O4 nanocrystals

NASA Astrophysics Data System (ADS)

Duan, Xiulan; Liu, Jian; Wang, Xinqiang; Jiang, Huaidong

2014-11-01

The distribution of cations in the spinel-type MgCr2yGa2-2yO4 (y = 0-0.6) nanocrystals and their optical properties as a function of annealing temperature and chromium content were investigated by using X-ray photoelectron spectroscopy (XPS) in combination with absorption spectroscopy. The cations in MgCr2yGa2-2yO4 nanocrystals are disorderly distributed with mixing of divalent and trivalent cations occupying the tetrahedral and octahedral sites. With the increase of annealing temperature, the inversion parameter (the fraction of Mg2+ ions in octahedral sites) decreases, which has the same varying tendency with the proportion of tetrahedral Ga3+ or Cr3+ ions. The inversion parameter increases with increasing Cr3+ concentration. The absorption spectra indicate that Cr3+ ions are located in the octahedral sites as well as in the tetrahedral sites. The fraction of tetrahedral Cr3+ decreases with Cr-enrichment. The optical absorption properties of Cr-doped MgGa2O4 nanocrystals may be tuned by varying the preparation temperature or Cr concentration.

Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

NASA Astrophysics Data System (ADS)

Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

2018-06-01

Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

Heavy metal content (Cd, Ni, Cr and Pb) in soil amendment with a low polluted biosolid

NASA Astrophysics Data System (ADS)

Gomez Lucas, Ignacio; Lag Brotons, Alfonso; Navarro-Pedreño, Jose; Belén Almendro-Candel, Maria; Jordán, Manuel M.; Bech, Jaume; Roca, Nuria

2016-04-01

The progressively higher water quality standards in Europe has led to the generation of large quantities of sewage sludge derived from wastewater treatment (Fytili and Zabaniotou 2008). Composting is an effective method to minimize these risks, as pathogens are biodegraded and heavy metals are stabilized as a result of organic matter transformations (Barker and Bryson 2002; Noble and Roberts 2004). Most of the studies about sewage sludge pollution are centred in medium and high polluted wastes. However, the aim of this study was to assess the effects on soil heavy metal content of a low polluted sewage sludge compost in order to identify an optimal application rate based in heavy metal concentration under a period of cultivation of a Mediterranean horticultural plant (Cynara carducnculus). The experiment was done between January to June: rainfall was 71 mm, the volume of water supplied every week was 10.5 mm, mean air temperatures was 14.2, 20.4 (maximum), and 9.2◦C (minimum). The soil was a clay-loam anthrosol (WRB 2006). The experimental plot (60 m2) was divided into five subplots with five treatments corresponding to 0, 2, 4, 6, and 8 kg compost/m2. Three top-soil (first 20 cm) samples from each treatment were taken (January, April and June) and these parameters were analysed: pH, electrical conductivity, organic matter and total content of heavy metals (microwave acid digestion followed by AAS-spectrometry determination). The results show that sewage sludge compost treatments increase the organic matter content and salinity (electrical conductivity of the soils) and diminish the pH. Cd and Ni total content in top-soil was affected and both slightly reduce their concentration. Pb and Cr show minor changes. In general, the application of this low polluted compost may affect the mobility of Cd and Ni due to the pH modification and the water added by irrigation along time but Pb and Cr remain their content in the top-soil. References Barker, A.V., and G.M. Bryson. 2002. "Bioremediation of Heavy Metals and Organic Toxicants by Composting." The Scientific World Journal 2: 407-420. Fytili, D., and A. Zabaniotou. 2008. "Utilization of Sewage Sludge in EU Application of Old and New Methods - A Review." Renewable and Sustainable Energy Reviews 12: 116-140. Noble, R., and S.J. Roberts. 2004. "Eradication of Plant Pathogens and Nematodes during composting: A Review." Plant Patology 53: 548-568.

Cr-substitution effect on structural, optical and electrical properties of Cr{sub x}Ce{sub 1−x}PO{sub 4} (x = 0.00, 0.08, 0.10 and 0.20) nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fadhalaoui, Amor; Dhaouadi, Hassouna, E-mail: dhaouadihassouna@yahoo.fr; Marouani, Houda

2016-01-15

Graphical abstract: The Cr{sub x}Ce{sub 1−x}PO{sub 4} (x = 0.00, 0.08, 0.10 and 0.20) nanorods synthesized under hydrothermal conditions. - Highlights: • Cr{sub x}Ce{sub 1−x}PO{sub 4} (x = 0.00–0.20) nanorods were synthesized by hydrothermal method. • Mean crystallite size of the products decreases with Cr-content. • Obvious improvements of the electrical conductivity comparatively to CePO4. - Abstract: Cr{sub x}Ce{sub 1−x}PO{sub 4} (x = 0.00–0.20) nanorods were synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), infrared absorption spectroscopy (IR) and transmission electron microscopy (TEM). The XRD results revealed the formation of a pure CePO{sub 4}more » hexagonal phase. TEM images confirmed the nano-size character of the as-prepared samples. Impedance spectroscopy analysis was used to analyze the electrical behavior of samples as a function of frequency at different temperatures. The increase of Cr-amount led to an increase in the total conductivities and decreased the activation energies (E{sub a} (x = 0.00) = 1.08 eV to E{sub a} (x = 0.20) = 0.80 eV). The optical properties of Cr{sub x}Ce{sub 1−x}PO{sub 4} nanomaterials were investigated using UV–vis spectroscopy. The band-gap energy values decreased with increasing Cr-content showing a red-shift trend. The improvement of the electrical conductivity and optical properties makes the Cr{sub x}Ce{sub 1−x}PO{sub 4} nanomaterials possible candidates to be used as electrolytes in solid oxide fuel cells, in photocatalytic and photovoltaic applications.« less

Precursor feeding studies and molecular characterization of geraniol synthase establish the limiting role of geraniol in monoterpene indole alkaloid biosynthesis in Catharanthus roseus leaves.

PubMed

Kumar, Krishna; Kumar, Sarma Rajeev; Dwivedi, Varun; Rai, Avanish; Shukla, Ashutosh K; Shanker, Karuna; Nagegowda, Dinesh A

2015-10-01

The monoterpene indole alkaloids (MIAs) are generally derived from strictosidine, which is formed by condensation of the terpene moiety secologanin and the indole moiety tryptamine. There are conflicting reports on the limitation of either terpene or indole moiety in the production of MIAs in Catharanthus roseus cell cultures. Formation of geraniol by geraniol synthase (GES) is the first step in secologanin biosynthesis. In this study, feeding of C. roseus leaves with geraniol, but not tryptophan (precursor for tryptamine), increased the accumulation of the MIAs catharanthine and vindoline, indicating the limitation of geraniol in MIA biosynthesis. This was further validated by molecular and in planta characterization of C. roseus GES (CrGES). CrGES transcripts exhibited leaf and shoot specific expression and were induced by methyl jasmonate. Virus-induced gene silencing (VIGS) of CrGES significantly reduced the MIA content, which was restored to near-WT levels upon geraniol feeding. Moreover, over-expression of CrGES in C. roseus leaves increased MIA content. Further, CrGES exhibited correlation with MIA levels in leaves of different C. roseus cultivars and has significantly lower expression relative to other pathway genes. These results demonstrated that the transcriptional regulation of CrGES and thus, the in planta geraniol availability plays crucial role in MIA biosynthesis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Assessment of Heavy Metal Pollution and Health Risks in the Soil-Plant-Human System in the Yangtze River Delta, China.

PubMed

Hu, Bifeng; Jia, Xiaolin; Hu, Jie; Xu, Dongyun; Xia, Fang; Li, Yan

2017-09-10

Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10 -3 ) was the largest among three age groups, followed by adults (6.998 × 10 -4 ) and seniors (5.488 × 10 -4 ). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni (0.018) > Hg (0.011) > Cr (0.010) > Pb (0.001). Therefore, Cd was most easily absorbed by crops, and different crops had different capacities to absorb HMs. The hazard quotient (HQ) represents the potential non-carcinogenic risk for an individual HM and it is an estimation of daily exposure to the human population that is not likely to represent an appreciable risk of deleterious effects during a lifetime. All the HQs of the HMs for the different age groups were significantly less than the alert value of 1.0 and were at a safe level. This indicated that citizens in the study area face low potential non-carcinogenic risk caused by HMs. The total carcinogens risks (TCRs) for children, adults, and seniors were 5.24 × 10 -5 , 2.65 × 10 -5 , and 2.08 × 10 -5 , respectively, all of which were less than the guideline value but at the alert level. Ingestion was the main pathway of carcinogen risk to human health.

Chromium-rich lawsonite in high-Cr eclogites from the Făgăras Massif (South Carpathians)

NASA Astrophysics Data System (ADS)

Negulescu, E.; Săbău, G.

2012-12-01

Lawsonite is a relatively rare phase in natural rocks, because of its thermal decomposition during exhumation, and Cr-bearing lawsonite being restricted to only a few occurrences worldwide. Here we report Cr-lawsonite in eclogites hosted in a medium-grade metamorphic complex. Several high-Cr eclogite lenses occur in the Topolog Complex (Făgăras Massif) of dominantly gneissic-amphibolitic composition. High Cr contents are the result of emerald-green mm-sized nodules containing Cr-rich minerals, embedded in a gray-green matrix of kyanite, clinopyroxene, garnet, amphibole, zoisite, and rutile. Garnets occur as porphyroblasts or in coronas around clinopyroxene aggregates probably replacing former magmatic pyroxene. Relict gabbroic textures (sometimes pegmatoid) and whole rock geochemistry indicate a gabbroic cumulate origin. The REE pattern, displaying a slight positive Eu anomaly and a tea spoon-shaped LREE depletion is also indicative of a cumulate origin, as also noted by Pe Piper & Piper (2002) for the Othrys gabbro (as well as others in the Vourinos and Pindos ophiolitic suites) with the same unusual REE-pattern. The emerald-green Cr-rich nodules are unevenly distributed in the rock, and always enclosed in Cr-rich clinopyroxenes (up to 5.46% Cr2O3) which may exhibit Cr-diffusion haloes towards normal Cr-free matrix pyroxene. The nodules consist of diablastic chromite, rutile and Cr-rich kyanite of up to 15.67 wt% Cr2O3, Cr-bearing epidote, to which Cr-rich staurolite (up to 10.45% Cr2O3; XMg up to 0.68) and Cr-rich lawsonite (up to 9.17% Cr2O3) may exceptionally associate. Cr concentrations in kyanite and lawsonite are, to our knowledge, the highest reported so far. Cr-lawsonite was identified in a single sample, as small single phase inclusions armoured in Cr-kyanite. Equilibrium PT-conditions of 2.6 GPa and 610o C were derived from the garnet-mantled clinopyroxene aggregates using multi-equilibria calculation with the PTGIBBS routine of Brandelik & Massonne (2004). These conditions fall still inside the stability field of lawsonite, below the thermal breakdown of this phase (Pawley, 1994), and consistent with its metastable persistence as armoured relics, during a near-isobaric late stage heating episode recorded in eclogites from the same structural setting (Săbău & Negulescu, 2006). Acknowledgements Financial support by grant PN-II-ID-PCE-2011-3-0030 Romanian Executive Unit for Financing Higher Education, Research, Development and Innovation. Prof. Hans-Joachim Masonne kindly provided access to the analytical facilities at Institut für Mineralogie und Kristallchemie in Stuttgart. References Brandelik, A., Massonne, H.-J. (2004). PTGIBBS - an Excel™ Visual Basic program for computing and visualizing thermodynamic functions and equilibria of rock-forming minerals. Computers and Geosciences 30, 909-923. Pawley, A. (1994) The pressure and temperature stability limits of lawsonite: Implication for H2O recycling in subduction zones. Contrib. Mineral. Petrol. 118, 99-108. Săbău, G., Negulescu, E. (2006) Metamorphic forming and evolution conditions of the eclogites in the Topolog Complex, Făgăras Mountains. Romanian Journal of Petrology 78, 39-46.

Non-classical behaviour of higher valence dopants in chromium (III) oxide by a Cr vacancy compensation mechanism

NASA Astrophysics Data System (ADS)

Carey, John J.; Nolan, Michael

2017-10-01

Modification of metal oxides with dopants that have a stable oxidation in their parent oxides which is higher than the host system is expected to introduce extra electrons into the material to improve carrier mobility. This is essential for applications in catalysis, SOFCs and solar energy materials. Density functional theory calculations are used to investigate the change in electronic and geometric structure of chromium (III) oxide by higher valence dopants, namely; Ce, Ti, V and Zr. For single metal doping, we find that the dopants with variable oxidation states, Ce, Ti and V, adopt a valence state of  +3, while Zr dopant has a  +4 oxidation state and reduces a neighbouring Cr cation. Chromium vacancy formation is greatly enhanced for all dopants, and favoured over oxygen vacancy formation. The Cr vacancies generate holes which oxidise Ce, Ti and V from  +3 to  +4, while also oxidising lattice oxygen sites. For Zr doping, the generated holes oxidise the reduced Cr2+ cation back to Cr3+ and also two lattice oxygen atoms. Three metal atoms in the bulk lattice facilitate spontaneous Cr vacancy from charge compensation. A non-classical compensation mechanism is observed for Ce, Ti and V; all three metals are oxidised from  +3 to  +4, which explains experimental observations that these metals have a  +4 oxidation state in Cr2O3. Charge compensation of the three Zr metals proceeds by a classical higher valence doping mechanism; the three dopants reduce three Cr cations, which are subsequently charge compensated by a Cr vacancy oxidising three Cr2+ to Cr3+. The compensated structures are the correct ground state electronic structure for these doped systems, and used as a platform to investigate cation/anion vacancy formation. Unlike the single metal doped bulks, preference is now given for oxygen vacancy formation over Cr vacancy formation, indicating that the dopants increase the reducibility of Cr2O3 with Ce doping showing the strongest enhancement. The importance of the correct ground state in determining the formation of defects is emphasised.

Biomonitoring chromium III or VI soluble pollution by moss chlorophyll fluorescence.

PubMed

Chen, Yang-Er; Mao, Hao-Tian; Ma, Jie; Wu, Nan; Zhang, Chao-Ming; Su, Yan-Qiu; Zhang, Zhong-Wei; Yuan, Ming; Zhang, Huai-Yu; Zeng, Xian-Yin; Yuan, Shu

2018-03-01

We systematically compared the impacts of four Cr salts (chromic chloride, chromic nitrate, potassium chromate and potassium bichromate) on physiological parameters and chlorophyll fluorescence in indigenous moss Taxiphyllum taxirameum. Among the four Cr salts, K 2 Cr 2 O 7 treatment resulted in the most significant decrease in photosynthetic efficiency and antioxidant enzymes, increase in reactive oxygen species (ROS), and obvious cell death. Different form the higher plants, although hexavalent Cr(VI) salt treatments resulted in higher accumulation levels of Cr and were more toxic than Cr(III) salts, Cr(III) also induced significant changes in moss physiological parameters and chlorophyll fluorescence. Our results showed that Cr(III) and Cr(VI) could be monitored distinguishably according to the non-photochemical quenching (NPQ) fluorescence of sporadic purple and sporadic lavender images respectively. Then, the valence states and concentrations of Cr contaminations could be evaluated according to the image of maximum efficiency of PSII photochemistry (Fv/Fm) and the quantum yield of PSII electron transport (ΦPSII). Therefore, this study provides new ideas of moss's sensibility to Cr(III) and a new method to monitor Chromium contaminations rapidly and non-invasively in water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Low-dose CT of postoperative pelvic fractures: a comparison with radiography.

PubMed

Eriksson, Thomas; Berg, Per; Olerud, Claes; Shalabi, Adel; Hänni, Mari

2018-01-01

Background Computed tomography (CT) is superior to conventional radiography (CR) for assessing internal fixation of pelvic fractures, but with a higher radiation exposure. Low-dose CT (LDCT) could possibly have a sufficient diagnostic accuracy but with a lower radiation dose. Purpose To compare postoperative diagnostic accuracy of LDCT and CR after open reduction and internal fixation of pelvic fracture. Material and Methods Twenty-one patients were examined with LDCT and CR 0-9 days after surgery. The examinations were reviewed by two musculoskeletal radiologists. Hardware, degree of fracture reduction, image quality, and reviewing time were assessed, and effective radiation dose was calculated. Inter-reader agreement was calculated. Results LDCT was significantly better than CR in determining whether hardware positioning was assessable ( P < 0.001). Acetabular congruence was assessable in all fractured patients with LDCT. In 12 of the 32 assessments with CR of patients with an acetabular fracture, joint congruence was not assessable due to overlapping hardware ( P = 0.001). Image quality was significantly higher for LDCT. Median time to review was 240 s for LDCT compared to 180 s for CR. Effective dose was 0.79 mSv for LDCT compared to 0.32 mSv for CR ( P < 0.001). Conclusion LDCT is more reliable than CR in assessing hardware position and fracture reduction. Joint congruency is sometimes not possible to assess with CR, due to overlapping hardware. The image quality is higher, but also the effective dose, with LDCT than with CR.