[Effect of chloride ion on corrosion of two commonly used dental alloys].

PubMed

Chen, Lei; Zhang, Weidan; Zhang, Yuanyuan

2014-11-01

To investigate the eff ect of chloride concentration on the corrosion of Co-Cr alloy and pure Ti in a simulated oral environment. The electrochemical corrosion tests of pure Ti and Co-Cr alloy were carried out in neutral artificial saliva solutions with different NaCl concentrations (0.9%, 2.0%, and 3.0%). Th e morphologies of corroded surface for pure Ti and Co-Cr alloy were observed by scanning electron microscope (SEM). Th e changes in the self-corrosion potentials (Ecorr) for pure Ti and Co-Cr alloy in three kinds of artificial saliva solutions was not obvious. However, the self-corrosion current densities (Icorr) of pure Ti were much lower than those of Co-Cr. The Icorr of Co-Cr alloy increased in a concentration-dependent manner of NaCl, whereas the breakdown potential (Eb) of Co-Cr alloy decreased in a concentration-dependent manner. Th e potential ranged for the breakdown of oxide film (Ev) was shortened in a concentration-dependent manner of NaCl. There was no obvious difference in the Icorr of pure Ti with different concentrations of NaCl. The breakdown potential was not seen according to the polarization curves. In a certain range, the increase of the concentration of Cl- leads to accelerate the corrosion behavior of Co-Cr alloy, but it does not affect pure Ti.

Effective As(III) Removal by A Multi-Charged Hydroacid Complex Draw Solute Facilitated Forward Osmosis-Membrane Distillation (FO-MD) Processes.

PubMed

Ge, Qingchun; Han, Gang; Chung, Tai-Shung

2016-03-01

Effective removal of As(III) from water by an oxalic acid complex with the formula of Na3[Cr(C2O4)3] (Na-Cr-OA) is demonstrated via an forward osmosis-membrane distillation (FO-MD) hybrid system in this study. Na-Cr-OA first proved its superiority as a draw solute with high water fluxes and negligible reverse fluxes in FO, then a systematic investigation of the Na-Cr-OA promoted FO process was conducted to ascertain the factors in As(III) removal. Relatively high water fluxes of 28 LMH under the FO mode and 74 LMH under the pressure retarded osmosis (PRO) mode were achieved when using a 1000 ppm As(III) solution as the feed and 1.0 M Na-Cr-OA as the draw solution at 60 °C. As(III) removal with a water recovery up to 21.6% (FO mode) and 48.3% (PRO mode) were also achieved in 2 h. An outstanding As(III) rejection with 30-3000 μg/L As(III) in the permeate was accomplished when As(III) feed solutions varied from 5 × 10(4) to 1 × 10(6) μg/L, superior to the best FO performance reported for As(III) removal. Incorporating MD into FO not only makes As(III) removal sustainable by reconcentrating the Na-Cr-OA solution simultaneously, but also reduces the As(III) concentration below 10 μg/L in the product water, meeting the WHO standard.

Chemical mechanisms and reaction rates for the initiation of hot corrosion of IN-738

NASA Technical Reports Server (NTRS)

Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

1984-01-01

Sodium-sulfate-induced hot corrosion of preoxidized IN-738 was studied at 975 C with special emphasis placed on the processes occurring during the long induction period. Thermogravimetric tests were run for predetermined periods of time, and then one set of specimens was washed with water. Chemical analysis of the wash solutions yielded information about water soluble metal salts and residual sulfate. A second set of samples was cross sectioned dry and polished in a nonaqueous medium. Element distributions within the oxide scale were obtained from electron microprobe X-ray micrographs. Evolution of SO was monitored throughout the thermogravimetric tests. Kinetic rate studies were performed for several pertinent processes; appropriate rate constants were obtained from the following chemical reactions: Cr2O3 + 2 Na2SO4(1) + 3/2 O2 yields 2 Na2CrO4(1) + 2 SO3(g)n TiO2 + Na2SO4(1) yields Na2O(TiO2)n + SO3(g)n TiO2 + Na2CrO4(1) yields Na2O(TiO2)n + CrO3(g).

Sodium sulfate-induced corrosion of pure nickel and superalloy Udimet 700 in a high velocity burner rig at 900 C

NASA Technical Reports Server (NTRS)

Misra, A. K.

1987-01-01

Sodium sulfate-induced corrosion of pure nickel and a commercial nickel-base superalloy, Udimet 700 (U-700), were studied at 900 C in a Mach 0.3 burner rig with different Na levels in the combustor. The corrosion rate of Ni was independent of the Na level in the combustor and considerably lower than that measured in laboratory salt spray tests. The lower rates are associated with the deposition of only a small amount of Na2SO4 on the surface of the NiO scale. Corrosion of U-700 was observed to occur in two stages. During the first stage, the corrosion proceeds by reaction of Cr2O3 scale with the Na2SO4 and evaporation of the Na2CrO4 reaction product from the surface of the corroding sample. Cr depletion in the alloy occurs and small sulfide particles are formed in the Cr depletion zone. Extensive sulfidation occurs during the second state of corrosion, and a thick scale forms. The relationship between the corrosion rate of U-700 and the Na level in the combustor gives a good correlation in the range of 0.3 to 1.5 ppm by weight Na. Very low levels of Na in the combustor cause accelerated oxidation of U-700 without producing the typical hot corrosion morphology.

Corrosion of metals and alloys in sulfate melts at 750 C

NASA Technical Reports Server (NTRS)

Misra, A. K.

1986-01-01

The corrosion of Ni, Co, Ni-10Cr, Co-21Cr, and IN738 was studied at 750 C in the presence of molten sulfate mixtures (Na2SO4-Li2SO4 and Na2SO4-CoSO4) and in an atmosphere consisting of O2 + 0.12 percent SO2-SO3. The corrosion was observed to be similar for both Na2SO4-Li2SO4 and Na2SO4-CoSO4 melts. The corrosion of Ni and Co took place by the formation of a mixed oxide plus sulfide scale, very similar to the corrosion in SO2 or SO3 alone. The initial stage for the corrosion of Ni-10Cr involved the formation of a thick NiO + Ni3S2 duplex scale, and Cr sulfide was formed during the later stages. A pitting type of morphology was observed for both Co-21Cr and IN738. The pit was Cr sulfide at the beginning, and subsequently the sulfides oxidized to Cr2O3. A base-metal oxide layer was present above the pit, and this was observed to be formed very early in the corrosion process. A mechanism is proposed to explain this. In general, the formation of sulfides appears to be the primary mode of degradation in mixed sulfide melts.

Nitric-glycolic flowsheet reduction/oxidation (redox) model for the defense waste processing facility (DWPF)

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

Jantzen, C. M.; Williams, M. S.; Edwards, T. B.

Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe +2/ΣFe ratios of between 0.09 and 0.33, retains radionuclides in the melt and thus the final glass. Specifically, long-lived radioactive 99Tc species are less volatile in the reduced Tc 4+ state as TcO 2 than as NaTcO 4 or Tc 2O 7, and ruthenium radionuclides in the reduced Ru 4+ state are insoluble RuO 2 inmore » the melt which are not as volatile as NaRuO 4 where the Ru is in the +7 oxidation state. Similarly, hazardous volatile Cr 6+ occurs in oxidized melt pools as Na 2CrO 4 or Na 2Cr 2O 7, while the Cr +3 state is less volatile and remains in the melt as NaCrO 2 or precipitates as chrome rich spinels. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam.« less

Density Functional Study for Chemical Reaction between Cr and Fe with Sodium Diethyldithiocarbamate (NaDDC)

NASA Astrophysics Data System (ADS)

Setiyanto, Henry; Muhida, Rifki; Kishi, Tomoya; Rahman, Md. Mahmudur; Dipojono, Hermawan K.; Diño, Wilson A.; Matsumoto, Shigeno; Kasai, Hideaki

Analytical chemistry in the perspective of ab initio molecular orbital calculation is introduced by investigating the chemical reaction between transition metals Cr and Fe with sodium diethyldithiocarbamate (NaDDC), a complexing agent to detect and extract Cr in human blood sample. Using density functional theory—based calculations, we determine the stable structure of the Cr-DDC and Fe-DDC complexes and obtain its dissociation energies. We found dissociation energy values of -3.24 and -2.67 eV for Cr and Fe complexes, respectively; and hence the formation of the former complex is more favorable than the formation of the latter.

Crystal field analysis of the energy level structure of Cs2NaAlF6:Cr3+

NASA Astrophysics Data System (ADS)

Rudowicz, C.; Brik, M. G.; Avram, N. M.; Yeung, Y. Y.; Gnutek, P.

2006-06-01

An analysis of the energy level structure of Cr3+ ions in Cs2NaAlF6 crystal is performed using the exchange charge model (ECM) together with the crystal field analysis/microscopic spin Hamiltonian (CFA/MSH) computer package. Utilizing the crystal structure data, our approach enables modelling of the crystal field parameters (CFPs) and thus the energy level structure for Cr3+ ions at the two crystallographically inequivalent sites in Cs2NaAlF6. Using the ECM initial adjustment procedure, the CFPs are calculated in the crystallographic axis system centred at the Cr3+ ion at each site. Additionally the CFPs are also calculated using the superposition model (SPM). The ECM and SPM predicted CFP values match very well. Consideration of the symmetry aspects for the so-obtained CFP datasets reveals that the latter axis system matches the symmetry-adapted axis system related directly to the six Cr-F bonds well. Using the ECM predicted CFPs as an input for the CFA/MSH package, the complete energy level schemes are calculated for Cr3+ ions at the two sites. Comparison of the theoretical results with the experimental spectroscopic data yields satisfactory agreement. Our results confirm that the actual symmetry at both impurity sites I and II in the Cs2NaAlF6:Cr3+ system is trigonal D3d. The ECM predicted CFPs may be used as the initial (starting) parameters for simulations and fittings of the energy levels for Cr3+ ions in structurally similar hosts.

Synthesis of single-crystal perovskite PbCrO3 through a new reaction route at high pressure

NASA Astrophysics Data System (ADS)

Han, Yunxia; Wang, Shanmin; Liu, Yinjuan; Ma, Dejiang; He, Duanwei; Zhao, Yusheng

2018-04-01

As a new member in the family of Mott system, perovskite PbCrO3 has recently been uncovered to exhibit fantastic structural transition under pressure, coupled with magnetic, electronic, and ferromagnetic transitions, which provide many opportunities for understanding of correlated system. However, it is still challenging to synthesize high-quality single-crystal PbCrO3, leading to the limited exploration of this Mott compound. In this work, we formulate a new high-pressure reaction route for preparation of high-quality PbCrO3 crystals between PbCl2 and Na2CrO4 at high pressure of 5-10 GPa and at high temperature of 750-1500°C. Because of the formation of reaction byproduct NaCl, the final product can readily be separated by washing with water. The obtained sample is in the form of single crystal with crystallite size up to 200 μm. In addition, combined with X-ray diffraction measurement, a tentative pressure-temperature synthesis diagram of PbCrO3 is mapped out from the reaction between PbCl2 and Na2CrO4 and the reaction mechanism is also explored in detail.

The role of NaCl in flame chemistry, in the deposition process, and in its reactions with protective oxides as related to hot corrosion

NASA Technical Reports Server (NTRS)

Kohl, F. J.; Stearns, C. A.

1979-01-01

Sodium chloride is believed to be the primary source of turbine engine contamination that contributes to hot corrosion. The behavior of NaCl-containing aerosols ingested with turbine intake air is very complex; some of the NaCl may vaporize during combustion while some may remain as particulates. The NaCl can lead to Na2SO4 formation by several possible routes or it can contribute to corrosion directly. Hydrogen or oxygen atom reaction with NaCl(c) was shown to result in the release of Na(g). Gaseous NaCl in flames can be partially converted to gaseous Na2SO4 by homogeneous reactions. The remaining gaseous NaCl and other Na-containing molecules can act as sodium carriers for condensate deposition of Na2SO4 on cool surfaces. A frozen boundary layer theory was developed to predict the rates of deposition. The condensed phase NaCl can be converted directly to condensed Na2SO4 by reaction with sulfur oxides and O2. Reaction of gaseous NaCl with Cr2O3 results in the vapor phase transport of chromium by the formation of complex Cr-containing gaseous molecules. Similar gaseous complexes are formed with molybdenum. The presence of gaseous NaCl was shown to affect the oxidation kinetics of Ni-Cr alloys. It also causes changes in the surface morphology of Al2O3 scales formed on Al-containing 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.

Microstructure and Corrosion Behavior of CrN and CrSiCN Coatings

NASA Astrophysics Data System (ADS)

Cai, Feng; Yang, Qi; Huang, Xiao; Wei, Ronghua

2010-07-01

Three CrN-based coatings were deposited on 17-4PH stainless steel substrate using plasma enhanced magnetron sputtering (PEMS) technique. The microstructure and corrosion resistance were evaluated to examine the effect of Si and C in the coatings. The three coating compositions were CrN(Cr0.69N0.31), CrSiCN-1 (Cr0.55Si0.014C0.14N0.3), and CrSiCN-2 (Cr0.43Si0.037C0.24N0.3). The testing results indicated that with the increase of Si concentration, the coating microstructure transformed from B1 structure to B1 + Si3N4 structure. All the three coating systems were subjected to electrochemical tests in 3.5% NaCl solution at room temperature. Potentiodynamic polarization results revealed that the CrSiCN-2 coating had a higher anodic current density and a lower corrosion potential when compared to the CrN and CrSiCN-1 coatings. Extended exposure in 3.5% NaCl caused several localized corrosion to the CrSiCN-2 coating due to the porous coating structure. Electrochemical impedance spectroscopic measurements demonstrated that the CrSiCN-1 has better corrosion resistance than CrN and CrSiCN-2.

Highly Corrosion Resistant and Sandwich-like Si3N4/Cr-CrNx/Si3N4 Coatings Used for Solar Selective Absorbing Applications.

PubMed

Zhang, Ke; Du, Miao; Haoa, Lei; Meng, Jianping; Wang, Jining; Mi, Jing; Liu, Xiaopeng

2016-12-14

Highly corrosion resistant, layer-by-layer nanostructured Si 3 N 4 /Cr-CrN x /Si 3 N 4 coatings were deposited on aluminum substrate by DC/RF magnetron sputtering. Corrosion resistance experiments were performed in 0.5, 1.0, 3.0, and 5.0 wt % NaCl salt spray at 35 °C for 168 h. Properties of the coatings were comprehensively investigated in terms of optical property, surface morphology, microstructure, elemental valence state, element distribution, and potentiodynamic polarization. UV-vis-near-IR spectrophotometer and FTIR measurements show that the change process in optical properties of Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coatings can be divided into three stages: a rapid active degradation stage, a steady passivation stage, and a transpassivation degradation stage. With the increase in the concentration of NaCl salt spray, solar absorptance and thermal emittance experienced a slight degradation. SEM images reveal that there is an increase in surface defects, such as microcracks and holes and -cracks. XRD and TEM measurements indicate that the phase structure changed partially and the content of CrO x and Al 2 O 3 has increased. Auger electron spectroscopy shows that the elements of Cr, N, and O have undergone a minor diffusion. Electrochemical polarization curves show that the as-deposited Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coatings have excellent corrosion resistance of 3633.858 kΩ, while after corroding in 5.0 wt % NaCl salt spray for 168 h the corrosion resistance dropped to 13.759 kΩ. However, these coatings still have an outstanding performance of high solar absorptance of 0.924 and low thermal emittance of 0.090 after corroding in 3.0 wt % NaCl salt spray for 120 h. Thus, the Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coating is a good choice for solar absorber coatings applied in the high-saline environment.

[Affinity of the elements in group VI of the periodic table to tumors and organs].

PubMed

Ando, A; Hisada, K; Ando, I

1976-10-01

In order to investigate the tumor affinity radioisotopes, chromium (51Cr), molybdenum (99Mo), tungsten (181W), selenium (75Se) and tellurium (127mTe)--the elements of group VI in the periodic table--were examined, using the rats which were subcutaneously transplanted with Yoshida sarcoma. Seven preprarations, sodium chromate (Na251CrO4), chromium chloride (51CrCl3), normal ammonium molybdate ((NH4)299MoO7), sodium tungstate (Na2181WO4), sodium selenate (Na275SeO4), sodium selenite (Na275SeO3) and tellurous acid (H2127mTeO3) were injected intravenously to each group of tumor bearing rats. These rats were sacrificed at various periods after injection of each preparation: 3 hours, 24 hours and 48 hours in all preparations. The radioactivities of the tumor, blood, muscle, liver, kidney and spleen were measured by a well-type scintillation counter, and retention values (in every tissue including the tumor) were calculated in percent of administered dose per g-tissue weight. All of seven preparations did not have any affinity for malignant tumor. Na251CrO4 and H2127mTeO3 had some affinity for the kidneys, and Na275SeO3 had some affinity for the liver. Na2181WO4 and (NH4)299MoO4 disappeared very rapidly from the blood and soft tissue, and about seventy-five percent of radioactivity was excreted in urine within first 3 hours.

A halogenophilic pathway in the reactions of transition metal carbonyl anions with [(η⁶-iodobenzene)Cr(CO)₃].

PubMed

Sazonov, Petr K; Ivushkin, Vasiliy A; Khrustalev, Victor N; Kolotyrkina, Natal'ya G; Beletskaya, Irina P

2014-09-21

The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in Cr(CO)3 complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack [(η(6)-iodobenzene)Cr(CO)3] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The reaction with K[CpFe(CO)2] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)2] (Cp* = η(5)-C5Me5) results in nucleophilic substitution to give [(η(6)-C6H5FeCp*(CO)2)Cr(CO)3]. Reaction with Na[Re(CO)5] quantitatively gives the iodo(acyl)rhenate anion Na[(η(6)-C6H5C(O)ReI(CO)4)Cr(CO)3] and in the case of K[Mn(CO)5] a mixture of σ-aryl complexes [(η(6)-C6H5Mn(CO)5)Cr(CO)3] and K[(η(6)-C6H5Mn(CO)4I)Cr(CO)3]. An analogous rhenium complex Na[(η(6)-C6H5Re(CO)4I)Cr(CO)3] is formed from the initial iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt4](+) salt) is established by X-ray diffraction analysis. The reaction of [(η(6)-chlorobenzene)Cr(CO)3] with K[CpFe(CO)2], in contrast, proceeds by the common S(N)2Ar mechanism.

Chemical reactions involved in the initiation of hot corrosion of IN-738

NASA Technical Reports Server (NTRS)

Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

1984-01-01

Sodium-sulfate-induced hot corrosion of preoxidized IN-738 was studied at 975 C with special emphasis placed on the processes occurring during the long induction period. Thermogravimetric tests were run for predetermined periods of time, and then one set of specimens was washed with water. Chemical analysis of the wash solutions yielded information about water soluble metal salts and residual sulfate. A second set of samples was cross sectioned dry and polished in a nonaqueous medium. Element distributions within the oxide scale were obtained from electron microprobe X-ray micrographs. Evolution of SO was monitored throughout the thermogravimetric tests. Kinetic rate studies were performed for several pertinent processes; appropriate rate constants were obtained from the following chemical reactions; Cr203 + 2 Na2S04(1) + 3/2 02 yields 2 Na2Cr04(1) + 2 S03(g)n TiO2 + Na2S04(1) yields Na20(T102)n + 503(g)n T102 + Na2Cro4(1) yields Na2(T102)n + Cr03(g).

Cr(VI) removal on visible light active TiO2 nanotube arrays

NASA Astrophysics Data System (ADS)

Bashirom, Nurulhuda; Zulkifli, Muhammad Afiq; Subagja, Subagja; Kian, Tan Wai; Matsuda, Atsunori; Lockman, Zainovia

2018-05-01

Self-organized TiO2 nanotube (TNT) arrays were fabricated by anodic oxidation of titanium foil in three different fluoride electrolytes: ethylene glycol (EG), glycerol, and sodium sulfate (Na2SO4) at different voltage and anodization time. In these electrolytes, the TNTs were produced in ˜ 2 µm long, but at the different diameter. The size of inner diameter can be arranged from the largest to the smallest value in the order of glycerol > EG > Na2SO4. Crystallization of the TNTs by annealing was led to the formation of anatase-TiO2. The sample can be activated under natural sunlight for reduction of hexavalent chromium, Cr(VI) into trivalent chromium, Cr(III). The reduction was thought to occur via synergistic reactions between adsorption and photoreduction. The result demonstrates 100 % of Cr(VI) removal efficiency over the TNTs grown in EG after 120 min. Whereas, only 48 % and 45 % of Cr(VI) can be removed over the TNTs fabricated in glycerol and Na2SO4, respectively. High photocatalytic activity of the TNTs-EG can be attributed to high crystallinity of anatase phase, enhanced Cr(VI) adsorption, and less electron-hole recombination due to smoother tube walls.

Preventive Strategies for Contrast-Induced Acute Kidney Injury in Patients Undergoing Percutaneous Coronary Procedures: Evidence From a Hierarchical Bayesian Network Meta-Analysis of 124 Trials and 28 240 Patients.

PubMed

Giacoppo, Daniele; Gargiulo, Giuseppe; Buccheri, Sergio; Aruta, Patrizia; Byrne, Robert A; Cassese, Salvatore; Dangas, George; Kastrati, Adnan; Mehran, Roxana; Tamburino, Corrado; Capodanno, Davide

2017-05-01

The effectiveness of currently available effective preventive strategies for contrast-induced acute kidney injury (CIAKI) is a matter of debate. We performed a Bayesian random-effects network meta-analysis of 124 trials (28 240 patients) comparing a total of 10 strategies: saline, statin, N-acetylcysteine (NAC), sodium bicarbonate (NaHCO 3 ), NAC+NaHCO 3 , ascorbic acid, xanthine, dopaminergic agent, peripheral ischemic preconditioning, and natriuretic peptide. Compared with saline, the risk of CIAKI was reduced by using statin (odds ratio [OR], 0.42; 95% credible interval [CrI], 0.26-0.67), xanthine (OR, 0.32; 95% CrI, 0.17-0.57), ischemic preconditioning (OR, 0.48; 95% CrI, 0.26-0.87), NAC+NaHCO 3 (OR, 0.50; 95% CrI, 0.33-0.76), NAC (OR, 0.68; 95% CrI, 0.55-0.84), and NaHCO 3 (OR, 0.66; 95% CrI, 0.47-0.90). The benefit of statin therapy was consistent across multiple sensitivity analyses, whereas the efficacy of all the other strategies was questioned by restricting the analysis to high-quality trials. Overall, high heterogeneity was observed for comparisons involving xanthine and ischemic preconditioning, although the impact of NAC and xanthine was probably influenced by publication bias/small-study effect. Hydration alone was the least effective preventive strategy for CIAKI. Meta-regressions did not reveal significant associations with baseline creatinine and contrast volume. In patients with diabetes mellitus, no strategy was found to reduce the incidence of CIAKI. In patients undergoing percutaneous coronary procedures, statin administration is associated with a marked and consistent reduction in the risk of CIAKI compared with saline. Although xanthine, NAC, NaHCO 3 , NAC+NaHCO 3 , ischemic preconditioning, and natriuretic peptide may have nephroprotective effects, these results were not consistent across multiple sensitivity analyses. © 2017 American Heart Association, Inc.

Effects of environment on the release of Ni, Cr, Fe, and Co from new and recast Ni-Cr alloy.

PubMed

Oyar, Perihan; Can, Gülşen; Atakol, Orhan

2014-07-01

The addition of previously cast alloy to new alloy for economic reasons may increase the release of elements. The purpose of this study was to analyze the effects of the immersion period, immersion media, and addition of previously cast alloy to new alloy on the release of elements. Disk-shaped specimens were prepared from a Ni-Cr alloy (Ni: 61 wt%, Cr: 26 wt%, Mo: 11 wt%, Si: 1.5 wt%, Fe, Ce, Al, and Co <1 wt%) (Remanium CS; Dentaurum) with new alloy (group N) and 50% new/50% recast alloy (group R). After the immersion of the specimens in both NaCl (pH 4) and artificial saliva (pH 6.7) for 3, 7, 14, 30, and 60 days, the release of ions was determined by using atomic absorption spectrometry. Data were analyzed with a 3-way ANOVA (α=.001). The release of Ni was significantly affected by the immersion period, of Ni and Cr by the alloy and media (P<.01), and of Fe by the alloy (P<.01). Ion release from the recast alloy in artificial saliva was 109.71 for Ni, 6.49 for Cr, 223.22 for Fe, and 29.90 μg/L for Co. The release of Co in NaCl was below the detection limit in both groups. The release of Ni in NaCl and artificial saliva increased with the length of the immersion period in both groups. The release of Cr and Fe was higher in artificial saliva than in NaCl in group R, regardless of the immersion period. The release of Co in NaCl was below the detection limit in both groups. Copyright © 2014 The Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Activated carbon with excellent chromium(VI) adsorption performance prepared by acid-base surface modification.

PubMed

Liu, S X; Chen, X; Chen, X Y; Liu, Z F; Wang, H L

2007-03-06

In the present work, activated carbon (AC) with excellent Cr(VI) adsorption performance especially at low concentrations was prepared by an acid-base surface modification method. Raw activated carbon (AC(0)) was first oxidized in boiling HNO(3) (AC(1)), then treated with a mixture of NaOH and NaCl (AC(2)). Batch equilibrium and continuous column adsorption were conducted to evaluate the adsorption performance. Boehm titration, elemental analysis, and N(2)/77K adsorption isotherm methods were used to characterize the surface properties and pore structure of modified ACs. The results revealed that the modified AC exhibited excellent Cr(VI) adsorption performance in terms of adsorption capacity and adsorption rate: AC(2)>AC(1)>AC(0). Modification caused S(BET) to decrease and the total number of surface oxygen acidic groups to increase. HNO(3) oxidization produced positive acid groups, and subsequently NaOH treatment replaced H(+) of surface acid groups by Na(+), and the acidity of AC decreased. The main cause of higher Cr(VI) adsorption capacity and rate for AC(2) was the presence of more oxygen surface acidic groups and suitable surface acidity. HNO(3)-NaOH modification shows potential for the preparation of high quality AC for the effective removal of low concentrations of Cr(VI).

Prediction of Cortical Defect Using C-Reactive Protein and Urine Sodium to Potassium Ratio in Infants with Febrile Urinary Tract Infection

PubMed Central

Jung, Su Jin

2016-01-01

Purpose We investigated whether C-reactive protein (CRP) levels, urine protein-creatinine ratio (uProt/Cr), and urine electrolytes can be useful for discriminating acute pyelonephritis (APN) from other febrile illnesses or the presence of a cortical defect on 99mTc dimercaptosuccinic acid (DMSA) scanning (true APN) from its absence in infants with febrile urinary tract infection (UTI). Materials and Methods We examined 150 infants experiencing their first febrile UTI and 100 controls with other febrile illnesses consecutively admitted to our hospital from January 2010 to December 2012. Blood (CRP, electrolytes, Cr) and urine tests [uProt/Cr, electrolytes, and sodium-potassium ratio (uNa/K)] were performed upon admission. All infants with UTI underwent DMSA scans during admission. All data were compared between infants with UTI and controls and between infants with or without a cortical defect on DMSA scans. Using multiple logistic regression analysis, the ability of the parameters to predict true APN was analyzed. Results CRP levels and uProt/Cr were significantly higher in infants with true APN than in controls. uNa levels and uNa/K were significantly lower in infants with true APN than in controls. CRP levels and uNa/K were relevant factors for predicting true APN. The method using CRP levels, u-Prot/Cr, u-Na levels, and uNa/K had a sensitivity of 94%, specificity of 65%, positive predictive value of 60%, and negative predictive value of 95% for predicting true APN. Conclusion We conclude that these parameters are useful for discriminating APN from other febrile illnesses or discriminating true APN in infants with febrile UTI. PMID:26632389

Na 3Cr 2P 3S 12 and K 3Cr 2P 3S 12: Two New One-Dimensional Thiophosphate Compounds with a Novel Structure

NASA Astrophysics Data System (ADS)

Coste, S.; Kopnin, E.; Evain, M.; Jobic, S.; Payen, C.; Brec, R.

2001-12-01

Two new alkali metal chromium thiophosphates, Na3Cr2P3S12 and K3Cr2P3S12, have been synthesized and their structure determined from single-crystal or powder X-ray diffraction analyses. These isostructural compounds, which exhibit a novel structural arrangement, crystallize in the monoclinic system (space group P21/c) with the cell parameters a=17.4076(10) Å, b=11.1723(10) Å, c=19.2502(11) Å, β=149.731(3)° (V=1887.1(2) Å3, Z=4) and a=17.9690(14) Å, b=12.0607(5) Å, c=19.3109(16) Å, β=150.008(3)° (V=2091.98(16) Å3, Z=4) for Na3Cr2P3S12 (I) and K3Cr2P3S12 (II), respectively. For (I), the single-crystal refinement led to R/Rw(F2)=0.0417/0.0650 (for 4125 independent reflections and 182 refined parameters). For (II), the Rietveld refinement led to Rp/Rwp=0.0181/0.0233 (for 90 refined parameters). In both materials, the structures consist of 1∞[Cr2P3S12]3- chains built upon two edge-sharing [CrS6] octahedra capped by two [PS4] tetrahedra defining isolated [Cr2P2S12]-8 entities. These entities are linked to each other through an extra [PS4] tetrahedral group. Magnetic measurements evidence antiferromagnetic coupling between Cr3+ cations. The charge balance of the phase is MI3CrIII2PV3S-II12.

Corrosion Fatigue Characteristics of 12Cr Alloy Steel in Na2SO4 Solution

NASA Astrophysics Data System (ADS)

Bae, D. H.; Cho, S. Y.

In order to estimate reliability of 12Cr alloy steel using as the turbine blade material of the steam power plant, its corrosion fatigue characteristics in Na2SO4 solution considering its percentage and temperature that were determined from the polarization test results were investigated, and compared with the results in air. The corrosion characteristic of 12Cr alloy steel was remarkably susceptible in 12.7wt.% (IM) Na2SO4 solution, and its susceptibility increased with the solution temperature increase. The corrosion fatigue characteristics in 12.7wt.% Na2SO4 solution were similar to that of in air at 25°C. The crack growth rate was however increased with the temperature of solution increase. The reasons showing such results are due to the difference of the crack growth mechanism according to the electro-chemical activity of the corrosion factors.

Volatile products in the corrosion of Cr, Mo, Ti and four superalloys exposed to O2 containing H2O and gaseous NaCl

NASA Technical Reports Server (NTRS)

Fryburg, G. C.; Miller, R. A.; Kohl, F. J.; Stearns, C. A.

1977-01-01

Cooled target collection techniques were used to study the formation of volatile products when samples of Cr, Ti, IN-738, 713C, NASA-TRW VIA and B-1900 were exposed, at elevated temperatures, to oxidizing environments containing H2O(g) and NaCl(g). Samples were heated to 1050 C in one atmosphere of slowly flowing oxygen, saturated with water at 21 C, and containing about 50 ppm NaCl(g). Volatile products were detected for all materials except B-1900 and Ti. High pressure mass spectrometric sampling was used to directly identify volatile products emanating from samples of Cr and IN-738 subject to the above environments.

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.

Investigation of Coronal Leakage of Root Fillings after Smear Layer Removal with EDTA or Er,Cr:YSGG Laser through Capillary Flow Porometry

PubMed Central

Vergauwen, Tom Edgard Maria; Michiels, Rafaël; Torbeyns, Dries; Meire, Maarten; De Moor, Roeland Jozef Gentil

2014-01-01

No studies have been performed evaluating the marginal seal of root fillings after direct exposure of root canal (RC) walls to Er,Cr:YSGG laser irradiation. Therefore, 75 root filled teeth (5 × 15–cold lateral condensation) were analyzed for through-and-through leakage (TTL) using capillary flow porometry (CFP). The cleaning protocol determined the experimental groups: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Er,Cr:YSGG lasing (dried RC), (3) NaOCl 2.5% + Er,Cr:YSGG lasing (dried RC), (4) SP + Er,Cr:YSGG lasing (wet RC), and (5) NaOCl 2.5% + Er,Cr:YSGG lasing (wet RC). Groups 6 to 10 consisted of the same filled teeth with resected apices. Resection was performed after the first CFP measurement. CFP was used to assess minimum, mean flow, and maximum pore diameters after 48 h. Statistics were performed using nonparametric tests (P > 0.05). Additional three roots per group were submitted to SEM of the RC walls. TTL was observed in all groups without statistically significant differences between the different groups for minimum, mean, and maximum pore diameter (P > 0.05). In this study, the use of EDTA and/or Er,Cr:YSGG laser did not reduce through-and-through leakage in nonresected and resected roots. PMID:24696685

Characterization of corrosion resistant on NiCoCr coating layer exposed to 5%NaCl

NASA Astrophysics Data System (ADS)

Sugiarti, E.; Sundawa, R.; Desiati, R. D.; Zaini, K. A.

2018-03-01

Highly corrosion resistant of carbon steel coated NiCoCr was applied in corrosive of marine environtment. Carbon steel coated NiCoCr was prepared by a two step technique of NiCo electro-deposition and Cr pack cementation. The samples were exposed to 5 wt.% NaCl for 48 and 168 hours. The microstructure and corrosion product were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The corrosion resistance of carbon steel coated NiCoCr was found to be better than that of carbon steel substrate without coating. The results showed the microstructure of 48 h corroded sample has duplex layer composed of inner α-(Ni,Co), α-Cr and outer Cr2O3, while a quite thin and continues protective oxide of Cr2O3 was observed in outer layer of 168 h corroded sample. The formation of oxide scale rich in Cr2O3 has contributed for the better corrosion resistance of carbon steel coated NiCoCr, whereas the formation of non protective oxide of iron might caused low corrosion resistance of carbon steel substrate.

Apoptosis of lymphocytes in the presence of Cr(V) complexes: role in Cr(VI)-induced toxicity.

PubMed

Vasant, C; Balamurugan, K; Rajaram, R; Ramasami, T

2001-08-03

Cr(VI) compounds have been declared as a potent occupational carcinogen by IARC (1990) through epidemiological studies among workers in chrome plating, stainless-steel, and pigment industries. Studies relating to the role of intermediate oxidation states such as Cr(V) and Cr(IV) in Cr(VI)-induced carcinogenicity are gaining importance. In this study, issues relating to toxicity elicited by Cr(V) have been addressed and comparisons made with those relating to Cr(VI) employing human peripheral blood lymphocytes. Lymphocytes have been isolated from heparinized blood by Ficoll-Hypaque density gradient centrifugation and exposed to Cr(V) complexes viz. sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)], 1 and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], 2 and Cr(VI). The phytohemagglutinin (PHA)-induced proliferation of lymphocytes has been found to be inhibited by the two complexes of Cr(V) and chromate Cr(VI) in a time- and concentration-dependent manner. Viability of cells decreases in the presence of Cr(V). Apoptosis appears to be the mode of cell death in the presence of both Cr(V) and Cr(VI). Pretreatment of cells with antioxidants before exposure to chromium(V) complexes reverse apoptosis partially. Possibility for the formation and implication of reactive oxygen species in Cr(V)-induced apoptosis of human lymphocyte cells has been indicated in this investigation. The intermediates of Cr(V) and radical species in the biotoxic pathways elicited by Cr(VI) seems feasible. Copyright 2001 Academic Press.

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.

Application of zeolitic material synthesized from thermally treated sediment to the removal of trivalent chromium from wastewater.

PubMed

Guan, Qingyu; Wu, Deyi; Lin, Yan; Chen, Xuechu; Wang, Xinze; Li, Chunjie; He, Shengbing; Kong, Hainan

2009-08-15

Zeolitic materials were synthesized from thermally treated sediment by alkali treatment using different NaOH/sediment ratios. Characterization of the materials was done by XRD, FTIR, cation exchange capacity and specific surface area. Use of high NaOH/sediment ratio favored the formation of zeolite. The potential value of the zeolitic materials for the retention of trivalent chromium from water was examined. The maximum of Cr(III) sorption by the zeolitic materials, determined by a repeated batch equilibration method, ranged from 38.9 to 75.8 mg/g which was much greater than that of the thermally treated sediment (6.3 mg/g). No release of sorbed Cr(III) by 1.0M MgCl(2) at pH 7 was observed but Cr(III) desorption by ionic electrolyte increased with decreasing pH. The zeolitic materials could completely remove Cr(III) from wastewater even in the presence of Na(+) and Ca(2+) with high concentrations with a dose above 2.5 g/L. The pH-dependent desorption behavior and the high selectivity of zeolitic material for Cr(III) were explained by sorption at surface hydroxyl sites and formation of surface 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.

Effect of the environment on wear ranking and corrosion of biomedical CoCrMo alloys.

PubMed

Muñoz, A Igual; Mischler, S

2011-03-01

The corrosion behaviour and the wear ranking of biomedical high carbon (HC) and low carbon (LC) CoCrMo alloys sliding against an alumina ball in four different simulated body fluids [NaCl and phosphate buffered solutions (PBS) with and without albumin] has been analyzed by tribocorrosion and electrochemical techniques. The effects of alloy and of albumin on corrosion depend on the base electrolyte: differences between LC and HC alloy were only observed in NaCl solutions but not in PBS. Albumin increased significantly corrosion of both alloys in PBS solutions while its effect in NaCl was smaller. The wear ranking of the HC and LC alloys also depends on the environment. In the present study, HC CoCrMo alloy had lower wear resistance in NaCl and PBS + albumin than the LC alloy, while no differences between both alloys were found in the other solutions. This was attributed to surface chemical effects affecting third body behaviour.

Chemical state of chromium in sewage sludge ash based phosphorus-fertilisers.

PubMed

Vogel, Christian; Adam, Christian; Kappen, Peter; Schiller, Tara; Lipiec, Ewelina; McNaughton, Don

2014-05-01

Sewage sludge ash (SSA) based P-fertilisers were produced by thermochemical treatment of SSA with Cl-donors at approximately 1000°C. During this thermochemical process heavy metals are separated as heavy metal chlorides via the gas phase. Chromium cannot be separated under normal conditions. The risk of the development of toxic Cr(VI) during the thermochemical process was investigated. X-ray Absorption Spectroscopy measurements showed that SSA and thermochemically treated SSA with CaCl2, MgCl2 and NaCl contain Cr(III) compounds only. In contrast, treating SSA with elevated quantities of Na2CO3, to enhance the plant-availability of the phosphate phases of the fertiliser, developed approximately 10-15% Cr(VI). Furthermore, Raman microspectroscopy showed that using Mg-carbonate reduces the risk of a Cr(VI) development during thermochemical treatment. Additionally, leaching tests showed that only a Cr-water solubility>10% is an indicator for Cr(VI) in SSA based P-fertilisers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrogen ions and organic acids secreted by ectomycorrhizal fungi, Pisolithus sp1, are involved in the efficient removal of hexavalent chromium from waste water.

PubMed

Shi, Liang; Xue, Jiawang; Liu, Binhao; Dong, Pengcheng; Wen, Zhugui; Shen, Zhenguo; Chen, Yahua

2018-06-13

Pisolithus sp1 is an ectomycorrhizal (ECM) fungi that was chosen during a screening test of six strains of ECM fungi due to its ability to tolerate and remove hexavalent chromium (Cr(VI)). The physiological responses of Pisolithus sp1 to Cr(VI) exposure, the relationship between Pisolithus sp1 and exogenously added organic acids (EAOAs) or Na 3 VO 4 (H + -ATPase inhibitor) and the ability of Pisolithus sp1 to reduce Cr(VI) in liquid culture were also investigated. Hydrogen ions (H + ), which were produced directly by Pisolithus sp1, reduced the pH of the medium and played an important role in Cr(VI) reduction; however, Na 3 VO 4 significantly inhibited this process and resulted in a decrease in the Cr(VI) reduction rates. Organic acids were secreted after the reduction in Cr(VI) by Pisolithus sp1, and EAOAs did not significantly affect Cr(VI) reduction; those results revealed the secondary role of organic acids in Cr(VI) reduction. The Cr(VI) removal rate of Pisolithus sp1 approached 99% after Cr(VI) treatment for 12 days. Overall, 75% of the Cr(VI) removal was due to extracellular reduction and 24% was due to adsorption. The results of this study provide a strong basis for using Cr(VI)-tolerant and Cr(VI)-reducing fungi, as well as ectomycorrhiza, in the remediation of Cr(VI)-contaminated sites. Copyright © 2018 Elsevier Inc. All rights reserved.

Sonocatalytic rapid degradation of Congo red dye from aqueous solution using magnetic Fe0/polyaniline nanofibers.

PubMed

Das, Raghunath; Bhaumik, Madhumita; Giri, Somnath; Maity, Arjun

2017-07-01

Nano-sized magnetic Fe 0 /polyaniline (Fe 0 /PANI) nanofibers were used as an effective material for sonocatalytic degradation of organic anionic Congo red (CR) dye. Fe 0 /PANI , was synthesized via reductive deposition of nano-Fe 0 onto the PANI nanofibers at room temperature. Prepared catalyst was characterized using HR-TEM, FE-SEM, XRD, FTIR instruments. The efficacy of catalyst in removing CR was assessed colorimetrically using UV-visible spectroscopy under different experimental conditions such as % of Fe 0 loading into the composite material, solution pH, initial concentration of dye, catalyst dosage, temperature and ultrasonic power. The optimum conditions for sonocatalytic degradation of CR were obtained at catalyst concentrations=500mg.L -1 , concentration of CR=200ppm, solution pH=neutral (7.0), temperature=30°C, % of Fe 0 loading=30% and 500W ultrasonic power. The experimental results showed that ultrasonic process could remove 98% of Congo red within 30min with higher Q max value (Q max =446.4 at 25°C). The rate of degradation of CR dye was much faster in this ultrasonic technique rather than conventional adsorption process. The degradation efficiency declined with the addition of common inorganic salts (NaCl, Na 2 CO 3 , Na 2 SO 4 and Na 3 PO 4 ). The rate of degradation suppressed more with increasing salt concentration. Kinetic and isotherm studies indicated that the degradation of CR provides pseudo-second order rate kinetic and Langmuir isotherm model compared to all other models tested. The excellent high degradation capacity of Fe 0 /PANI under ultrasonic irradiation can be explained on the basis of the formation of active hydroxyl radicals (OH) and subsequently a series of free radical reactions. Copyright © 2017 Elsevier B.V. All rights reserved.

Response surface methodology investigation into optimization of the removal condition and mechanism of Cr(Ⅵ) by Na2SO3/CaO.

PubMed

Zhao, Shengxin; Chen, Zhonglin; Shen, Jimin; Kang, Jing; Qu, Yanfeng; Wang, Binyuan; Wang, Xin; Yuan, Lie

2017-11-01

The removal of Cr(Ⅵ) by chemical reduction-precipitation is widely applied in wastewater treatment plants. Nevertheless, the formation of Cr(OH) 3 with gel properties has weak settlement performance, making it necessary to add a coagulant aid to reduce the settling time and improve the settling effect. In this investigation, a high concentration of Cr(Ⅵ) was removed using Na 2 SO 3 as a reducing agent and CaO as a coagulant. An improved reduction and precipitation experiment was modeled by applying a three-factor central composite experimental design (CCD). To reveal as many mechanisms as possible for Cr T removal, other verification experiments were performed. The Cr T removal efficiency decreased, which can be explained by the following three reasons: dissolution of Cr(Ⅲ), competition for adsorption between Ca 2+ and Cr(Ⅲ) at different coagulation times, and formation of a solubility complex with Cr(Ⅲ) due to the surplus SO 3 2- in solution. The increasing Cr T removal efficiency can be explained by the following two reasons: dissolved Ca 2+ from CaO can neutralize CrO 2 - that is produced by the dissolution of Cr(OH) 3 in alkaline solution and can broaden the optimal final pH range of coagulation. Ca 2+ could also strengthen the Cr T removal through adsorption bridging and co-precipitation with CaO as the core of flocs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, Rietveld refinements, Infrared and Raman spectroscopy studies of the sodium diphosphate NaCryFe1-yP2O7 (0 ≤ y ≤ 1)

NASA Astrophysics Data System (ADS)

Bih, H.; Saadoune, I.; Bih, L.; Mansori, M.; ToufiK, H.; Fuess, H.; Ehrenberg, H.

2016-01-01

In the present study we report on the synthesis and crystal structure studies of NaCryFe1-yP2O7 sodium diphosphate solid solution (0 ≤ y ≤ 1). The X-ray diffraction shows that these compounds are isostructural with NaFeP2O7 and NaCrP2O7 (space group P21/c (C2h5) Z = 4). The Rietveld refinements based on the XRD patterns show the existence of a continuous solid solution over the whole composition range (0 ≤ y ≤ 1). A continuous evolution of the monoclinic unit cell parameters was obtained. The transition metal ions (Cr3+ and/or Fe3+) connect the diphosphate anions forming a three-dimensional network with cages filled by Na+ cations. IR and Raman spectra have been interpreted using factor group analysis. A small shift of the band frequencies is observed when Fe is substituted by Cr. The POP bridge angles are determined from Lazarev's relation and agree well with those deduced from the crystal structure refinement.

Biosorption of Cr(VI) and As(V) at high concentrations by organic and inorganic wastes

NASA Astrophysics Data System (ADS)

María Rivas Pérez, Ivana; Paradelo Núñez, Remigio; Nóvoa Muñoz, Juan Carlos; Arias Estévez, Manuel; José Fernández Sanjurjo, María; Álvarez Rodríguez, Esperanza; Núñez Delgado, Avelino

2016-04-01

The potential reutilization of several wastes as biosorbents for As(V) and Cr(VI) has been assessed in batch-type experiments. The materials studied were one inorganic: mussel shell, and three organic: pine bark, oak ash and hemp waste. Batch experiments were performed in order to determine the removal capacity of the wastes under conditions of high As(V) and Cr(VI) loads. For this, 3 g of each waste material were added with 30 mL NaNO3 0.01 M dissolutions containing 0, 0.5, 1.5, 3 and 6 mmol As(V) L-1 or Cr(VI) L-1, prepared from analytical grade Na2HAsO4 or K2Cr2O7. The resulting suspensions were shaken for 24 h, centrifuged and filtered. Once each batch experiment corresponding to the sorption trials ended, each individual sample was added with 30 mL of NaNO3 0.01 M to desorb As(V) or Cr(VI), shaken for 24 h, centrifuged and filtered as in the sorption trials. Oak ash showed high sorption (>76%) and low desorption (<7%) for As(V), which was lower on mussel shell (<31%), hemp waste (<16%) and pine bark (<9.9%). In turn, pine bark showed the highest Cr(VI) sorption (>98%) with very low desorption (<0.5%), followed by oak ash (27% sorption), and hemp waste and mussel shell, that presented very low Cr(VI) sorption (<10%). Sorption data for both elements were better described by the Freundlich than by the Langmuir model. The variable results obtained for the removal of the two anionic contaminants for a given sorbent suggest that different mechanisms govern removal from the solution in each case. In summary, oak ash would be an efficient sorbent material for As(V), but not for Cr(VI), while pine bark would be the best sorbent for Cr(VI) removal.

Platelet aggregation caused by Carybdea rastonii toxins (CrTX-I, II and III) obtained from a jellyfish, Carybdea rastonii.

PubMed

Azuma, H; Sekizaki, S; Satoh, A; Nakajima, T

1986-05-01

The pharmacological mechanisms of platelet aggregation induced by highly toxic proteins (CrTX-I, CrTX-II, and CrTX-III) obtained from tentacles of a jellyfish, Carybdea rastonii, were investigated. When the partially purified toxin (pCrTX) and CrTXs were added to the citrated platelet-rich plasma (PRP), aggregation was produced in a concentration-dependent manner. The activity of CrTXs was approximately 100 times more potent than pCrTX. The CrTXs-induced aggregation was little affected by indomethacin and quinacrine at concentrations sufficient to inhibit arachidonic acid- and collagen-induced aggregation. The CrTXs-induced aggregation in washed platelets was significantly augmented in the presence of Ca2+. The pretreatment with verapamil failed to modify this augmentation of aggregation. The concentration of cytoplasmic-free calcium ([Ca2+]i) of platelets was increased by CrTXs at the same concentrations that produced aggregation. This effect of CrTXs was again little affected by verapamil. CrTXs at the same concentrations as those that produced aggregation and increased [Ca2+]i caused depolarization of platelets, which was unchanged after pretreatment with sodium or potassium transport inhibitors. CrTX-I significantly increased the 22Na flux into platelets and this effect of CrTX-I was unaffected by tetrodotoxin. The CrTX-I-induced aggregation, depolarization, and increase in [Ca2+]i were all significantly attenuated in the low Na+ medium. These results suggest that CrTXs cause a massive depolarization by increasing cation permeability and this generalized depolarization permits an inward movement of Ca2+ down its electrochemical gradient which, in turn, triggers platelet aggregation.

Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries

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

Cao, Ming -Hui; Wang, Yong; Shadike, Zulipiya

Chromium-based layered cathode materials suffer from the irreversible disproportionation reaction of Cr 4+ to Cr 3+ and Cr 6+, which hinders the reversible multi-electron redox of Cr ions in layered cathodes, and limits their capacity and reversibility. To address this problem, a novel O3-type layer-structured transition metal oxide of NaCr 1/3Fe 1/3Mn 1/3O 2 (NCFM) was designed and studied as a cathode material. A high reversible capacity of 186 mA h g –1 was achieved at a current rate of 0.05C in a voltage range of 1.5 to 4.2 V. X-ray diffraction revealed an O3 → (O3 + P3) →more » (P3 + O3'') → O3'' phase-transition pathway for NCFM during charge. X-ray absorption, X-ray photoelectron and electron energy-loss spectroscopy measurements revealed the electronic structure changes of NCFM during Na + deintercalation/intercalation processes. It is confirmed that the disproportionation reaction of Cr 4+ to Cr 3+ and Cr 6+ can be effectively suppressed by Fe 3+ and Mn 4+ substitution. Lastly, these results demonstrated that the reversible multi-electron oxidation/reduction of Cr ions can be achieved in NCFM during charge and discharge accompanied by CrO 6 octahedral distortion and recovery.« less

Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries

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

Cao, Ming-Hui; Wang, Yong; Shadike, Zulipiya

Chromium-based layered cathode materials suffer from the irreversible disproportionation reaction of Cr4+ to Cr3+ and Cr6+, which hinders the reversible multi-electron redox of Cr ions in layered cathodes, and limits their capacity and reversibility. To address this problem, a novel O3-type layer-structured transition metal oxide of NaCr1/3Fe1/3Mn1/3O2 (NCFM) was designed and studied as a cathode material. A high reversible capacity of 186 mA h g-1 was achieved at a current rate of 0.05C in a voltage range of 1.5 to 4.2 V. X-ray diffraction revealed an O3 → (O3 + P3) → (P3 + O3'') → O3'' phase-transition pathway formore » NCFM during charge. X-ray absorption, X-ray photoelectron and electron energy-loss spectroscopy measurements revealed the electronic structure changes of NCFM during Na+ deintercalation/intercalation processes. It is confirmed that the disproportionation reaction of Cr4+ to Cr3+ and Cr6+ can be effectively suppressed by Fe3+ and Mn4+ substitution. These results demonstrated that the reversible multi-electron oxidation/reduction of Cr ions can be achieved in NCFM during charge and discharge accompanied by CrO6 octahedral distortion and recovery.« less

Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries

DOE PAGES

Cao, Ming -Hui; Wang, Yong; Shadike, Zulipiya; ...

2017-02-14

Chromium-based layered cathode materials suffer from the irreversible disproportionation reaction of Cr 4+ to Cr 3+ and Cr 6+, which hinders the reversible multi-electron redox of Cr ions in layered cathodes, and limits their capacity and reversibility. To address this problem, a novel O3-type layer-structured transition metal oxide of NaCr 1/3Fe 1/3Mn 1/3O 2 (NCFM) was designed and studied as a cathode material. A high reversible capacity of 186 mA h g –1 was achieved at a current rate of 0.05C in a voltage range of 1.5 to 4.2 V. X-ray diffraction revealed an O3 → (O3 + P3) →more » (P3 + O3'') → O3'' phase-transition pathway for NCFM during charge. X-ray absorption, X-ray photoelectron and electron energy-loss spectroscopy measurements revealed the electronic structure changes of NCFM during Na + deintercalation/intercalation processes. It is confirmed that the disproportionation reaction of Cr 4+ to Cr 3+ and Cr 6+ can be effectively suppressed by Fe 3+ and Mn 4+ substitution. Lastly, these results demonstrated that the reversible multi-electron oxidation/reduction of Cr ions can be achieved in NCFM during charge and discharge accompanied by CrO 6 octahedral distortion and recovery.« less

Effect of Fe-site isovalent and aliovalent doping on the magnetic, electric and optical properties of BiFe0.875Cr0.125O3

NASA Astrophysics Data System (ADS)

Zhou, Yunhua; Zhang, Ren; Fan, Yingfang; Wang, Zhongchao; Mao, Weiwei; Zhang, Jian; Min, Yonggang; Yang, Jiangping; Pu, Yong; Li, Xing'ao

2018-02-01

The magnetic, electric and optical properties of BiFe0.875Cr0.125O3 (BFCO) doped with aliovalent ions (Na+, Mg2+) and isovalent ion (Al3+) are investigated by the first principle spin-polarized density functional theory calculations. It is demonstrated that the substitution of M (M = Na+, Mg2+, Al3+) for Fe can produce net magnetic moments of 3.0, 2.0 and 3.0 μB, respectively. Besides, Na+ doped BFCO exhibits metallicity while Mg2+ doped system behaves as half-metallicity. Systematic study of electronic structures show that this conversion from semiconductor (BFCO) to half-metal or metal is mainly attributed to the shifting of O 2p, Bi 6s, and Cr 3d states induced by doping with aliovalent Na+ or Mg2+. Furthermore, the aliovalent ions doped samples express high static dielectric constants of 12.08, 29.44, large refractive indexs of 5.41, 3.46 and both their absorption edges near zero, suggesting advanced optical response in visible region of the doped samples.

Materials corrosion in molten lithium fluoride-sodium fluoride-potassium fluoride eutectic salt

NASA Astrophysics Data System (ADS)

Olson, Luke Christopher

Static corrosion studies were undertaken to determine the compatibility of several candidate high temperature materials for a heat transfer loop in a molten alkali fluoride eutectic salt, LiF-NaF-KF: 46.5-11.5-42 mol % (commonly referred to as FLiNaK), as well as a molten chloride near eutectic salt, KCl-MgCl2: 68-32 mol %. Several high temperature alloys: Hastelloy-N, Hastelloy-X, Haynes-230, Inconel-617, and Incoloy-800H, Nb-1Zr, a nearly pure Ni alloy Ni-201, and a C/SiSiC ceramic were exposed to molten FLiNaK at 850°C for 500 h in sealed graphite crucibles under an argon cover gas. Corrosion occurred predominantly from dealloying of Cr from the Cr bearing alloys, an effect that was particularly pronounced at the grain boundaries. Corrosion was noted to occur from selective attack of the Si phase in the C/SiSiC ceramic. Alloy weight-loss/area due to molten fluoride salt exposure correlated with the initial Cr-content of the alloys, and was consistent with the Cr-content measured in the salts after corrosion tests. The alloys' weight-loss/area was also found to correlate to the concentration of carbon present in the nominally 20% Cr containing alloys, due to the formation of chromium carbide phases at the grain boundaries. The corrosion mechanisms for the chloride based salt were found to be similar to those observed in FLiNaK, but the chemical attack was found to be less aggressive. Sulfamate Ni electroplating and Mo plasma spraying of Fe-Ni-Cr alloy coupons was investigated to mitigate Cr dissolution. A chemical vapor deposited pyrolytic carbon and SiC coating was also investigated to protect the C/SiSiC composites. Results indicate that Ni-plating has the potential to provide protection against alloy corrosion in molten fluoride salts. Furthermore, the presence of a chromium-oxide interlayer at the interface of the Ni-plating and alloy substrate can further improve the efficacy of the Ni-plating. The pyrolytic carbon and SiC coating on the C/SiSiC composites was effective in eliminating the attack of the Si phase in the composites. Delamination of the Mo coating in FLiNaK prevented further investigation of this promising approach.

Remineralization effect of CPP-ACP and fluoride for white spot lesions in vitro.

PubMed

Oliveira, Gustavo M S; Ritter, André V; Heymann, Harald O; Swift, Edward; Donovan, Terry; Brock, Guy; Wright, Tim

2014-12-01

This in vitro study compared the remineralization effect on white spot lesions of casein phosphopeptide-amorphous calcium phosphate crème, or CPP-ACP (MI Paste™), 1.1% NaF dentifrice containing 5000ppm of fluoride (ControlRX™), or CPP-ACP crème with 900ppm of fluoride (MI Paste Plus™) with that of a control. Artificial white spot lesions were created on smooth enamel surfaces of sound molars using a previously reported demineralization model. Specimens were randomly assigned to four treatments (n=35) with a pH-cycling model over 30 days: Control (no treatment); MI Paste (10% CPP-ACP crème); F5000 (1.1% NaF dentifrice); or MI Paste Plus (10% CPP-ACP plus 900ppm fluoride crème). Products were applied following manufacturers' directions. Changes in mean lesion depth expressed by percent fluorescence loss (ΔF%), and lesion area (mm(2)) from baseline to after treatment were measured with light-induced fluorescence (QLF). Mean values of each parameter were compared between groups (p<0.05). The remineralization pattern for the F5000 group was unique with marked initial remineralization during the first 10 days and little subsequent change. Based on mean lesion area, the F5000 demonstrated greater remineralization than Control, MI Paste and MI Paste Plus groups. Based on mean fluorescence loss, the F5000 group showed improved remineralization relative to MI Paste Plus, but did not differ statistically from the Control at the end of 30 days. The 1.1% NaF dentifrice demonstrated overall greater remineralization ability than 10% CPP-ACP crème. However, the 1.1% NaF dentifrice was only as effective as the Control to reduce fluorescence loss. This study showed that a 1.1% NaF dentifrice (5000ppm) demonstrated greater remineralization ability than the CPP-ACP topical tooth crème and that the addition of fluoride to its formulation seems to enhance remineralization. Saliva also has the ability to exert an important remineralization effect over time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ehimeite, NaCa2Mg4CrSi6Al2O22(OH)2: The first Cr-dominant amphibole from the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan

NASA Astrophysics Data System (ADS)

Nishio-Hamane, Daisuke; Ohnishi, Masayuki; Minakawa, Tetsuo; Yamaura, Jun-Ichi; Saito, Shohei; Kadota, Ryo

The first Cr-dominant amphibole, ehimeite, ideally NaCa2Mg4CrSi6Al2O22(OH)2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kämmererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2Vcalc. = 53°. It has a Mohs’ hardness of 6 and densities of 3.08(3) g/cm3 (measured using heavy liquids) and 3.121 g/cm3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na0.88K0.07)Σ0.95(Ca1.89Na0.02Mg0.09)Σ2.00(Mg4.03Cr0.62Al0.19Fe3+0.07Fe2+0.07Ti0.03)Σ5.00(Si6.14Al1.86)Σ8.00O22(OH)2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa2Mg4(Cr, Al)Si6Al2O22(OH)2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) Å, b = 18.0009(12) Å, c = 5.2850(7) Å, β = 105.400(7)°, V = 909.6 (17) Å3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (Å), I/I0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.

Antidepressant effect detected on proton magnetic resonance spectroscopy in drug-naïve female patients with first-episode major depression.

PubMed

Kaymak, Semra Ulusoy; Demir, Başaran; Oğuz, Kader Karli; Sentürk, Senem; Uluğ, Berna

2009-06-01

Recent neuroimaging studies support functional and structural alterations in the dorsolateral prefrontal cortex (DLPFC), particularly on the left side in patients with major depressive disorders (MDD). The aim of the present study was to examine the biochemical characteristics of left DLPFC as measured on proton ((1)H) magnetic resonance spectroscopy (MRS) in patients with drug-naïve first-episode MDD and a healthy control group. A second aim was to assess the effect of antidepressant treatment on the metabolites of DLPFC. Short-echo single-voxel (1)H-MRS was done for the left DLPFC in 17 female drug-free MDD patients (mean age +/- SD, 30.9 +/- 6.9 years) and 13 matched control subjects (mean age +/- SD, 29.1 +/- 6.2 years) and was repeated at 8 weeks following antidepressant treatment. Comparison of baseline values indicated that there were no significant differences in any of the metabolite ratios (N-acetyl aspartate/creatine [NAA/Cr], myoinositol [Ino]/Cr, and choline [Cho]/Cr) between patients and controls. Significant differences were detected between pre- and post-treatment Ino/Cr ratios (0.67 +/- 0.13, 0.58 +/- 0.22, P = 0.032, respectively), although there was no difference in NAA/Cr and Cho/Cr ratios. Although no significant metabolic alterations exist in female patients with drug-naïve first-episode MDD as evaluated on (1)H-MRS, an increase in Ino/Cr was observed following 8-week antidepressant treatment. These findings give rise to the possibility that non-neuronal cells, particularly glial cells that are probably damaged, play a role in the action of antidepressant treatment.

Genome-Wide Association Study on the Development of Cross-Reactive Neutralizing Antibodies in HIV-1 Infected Individuals

PubMed Central

Euler, Zelda; van Gils, Marit J.; Boeser-Nunnink, Brigitte D.; Schuitemaker, Hanneke; van Manen, Daniëlle

2013-01-01

Broadly neutralizing antibodies may protect against HIV-1 acquisition. In natural infection, only 10–30% of patients have cross-reactive neutralizing humoral immunity which may relate to viral and or host factors. To explore the role of host genetic markers in the formation of cross-reactive neutralizing activity (CrNA) in HIV-1 infected individuals, we performed a genome-wide association study (GWAS), in participants of the Amsterdam Cohort Studies with known CrNA in their sera. Single-nucleotide polymorphisms (SNPs) with the strongest P-values are located in the major histocompatibility complex (MHC) region, close to MICA (P = 7.68×10−7), HLA-B (P = 6.96×10−6) and in the coding region of HCP5 (P = 1.34×10−5). However, none of the signals reached genome-wide significance. Our findings underline the potential involvement of genes close or within the MHC region with the development of CrNA. PMID:23372753

The Lunar Atmosphere as a Cosmic-Ray Detector

NASA Technical Reports Server (NTRS)

Wilson, T. L.

2007-01-01

The recent discovery of a tenuous sodium (Na) atmosphere on the Moon and Mercury has renewed interest in studying the lunar atmosphere since the physics involved for the two bodies is thought to be of similar nature. Na came as a surprise because it had been missed by in situ UV measurements made during the Apollo program. The new lunar observations involve the visible D1 (5896 ) and D2 (5890 ) wavelengths which are highly efficient at scattering sunlight. Although its lunar source and morphology is still not completely understood, Na is present as a collisionless exosphere - apparently in the form of a cometary-type coma with a tail that can extend hundreds of lunar radii during Leonid showers. The global shape of the atmosphere, in particular for the shaded antisolar side, has been modelled by Smyth. Since planetary atmospheres can be used as cosmic-ray (CR) spectrometers by means of their fluorescence excited by CR-induced air shower particles, the subject of the Moon s atmosphere as a CR detector will be discussed here.

Study of the effects of gaseous environmental on the hot corrosion of superalloy materials

NASA Technical Reports Server (NTRS)

Smeggil, J. G.

1981-01-01

Studies have been conducted to examine the effect of low concentrations of NaCl(g) on the high temperature oxidation behavior of complex superalloys and potential coating formulations modified by silicon and reactive element (i.e., yttrium and hafnium) additions. Depending on alloy composition, a variety of effects were thermogravimetrically produced. Aluminum free alloys such as MAR-M509 and Hastelloy X with molybdenum and tungsten in solid solution showed accelerated (or breakaway) kinetics similar to that observed for Ni-Cr alloys. For IN-792, an alloy high in chromium and low in aluminum, molybdenum and tungsten present in solid solution does not adversely affect oxidation kinetics in the presence of NaCl(g). On the other hand, nickel-base alloys high in aluminum and molybdenum are catastrophically attacked by NaCl-bearing atmospheres. Silicon additions were, in general, observed to slightly improve the oxidation resistance of Ni, Ni-40Cr and CoCrAlY compositions in NaCl(g)-bearing atmospheres. To the degree that processes responsible for Al2O3 whisker formation deleteriously affect protective scale adherence, the addition of yttrium or hafnium can inhibit such whisker growth.

Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders

PubMed Central

Chen, Xiaoyu; Li, Yongxia; Huang, Lan; Zou, Dan; Wu, Enxi; Liu, Yanjun; Xie, Yuanyan; Yao, Rui; Liao, Songyi; Wang, Guangrong

2017-01-01

Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH4)2C2O4·H2O and Na2CO3) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7–10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na2CO3 precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed. PMID:28934147

Synthesis and investigation of novel cathode materials for sodium ion batteries

NASA Astrophysics Data System (ADS)

Sawicki, Monica

Environmental pollution and eventual depletion of fossil fuels and lithium has increased the need for research towards alternative electrical energy storage systems. In this context, research in sodium ion batteries (NIBs) has become more prevalent since the price in lithium has increased due to its demand and reserve location. Sodium is an abundant resource that is low cost, and safe; plus its chemical properties are similar to that of Li which makes the transition into using Na chemistry for ion battery systems feasible. In this study, we report the effects of processing conditions on the electrochemical properties of Na-ion batteries made of the NaCrO2 cathode. NaCrO2 is synthesized via solid state reactions. The as-synthesized powder is then subjected to high-energy ball milling under different conditions which reduces particle size drastically and causes significant degradation of the specific capacity for NaCrO2. X-ray diffraction reveals that lattice distortion has taken place during high-energy ball milling and in turn affects the electrochemical performance of the cathode material. This study shows that a balance between reducing particle size and maintaining the layered structure is essential to obtain high specific capacity for the NaCrO2 cathode. In light of the requirements for grid scale energy storage: ultra-long cycle life (> 20,000 cycles and calendar life of 15 to 20 years), high round trip efficiency (> 90%), low cost, sufficient power capability, and safety; the need for a suitable cathode materials with excellent capacity retention such as Na2MnFe(CN)6 and K2MnFe(CN)6 will be investigated. Prussian blue (A[FeIIIFeII (CN)6]•xH2O, A=Na+ or K+ ) and its analogues have been investigated as an alkali ion host for use as a cathode material. Their structure (FCC) provides large ionic channels along the direction enabling facile insertion and extraction of alkali ions. This material is also capable of more than one Na ion insertion per unit formula which holds great promise in increasing the energy density of the NIB. The electrochemical performance of the cathode material will be analyzed using cyclic voltammetry, and galvanostatic charge/discharge investigation.

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.

Simultaneous Formation of Artificial SEI Film and 3D Host for Stable Metallic Sodium Anodes.

PubMed

Zhang, Di; Li, Bin; Wang, Shuai; Yang, Shubin

2017-11-22

Metallic sodium is a promising anode for sodium-based batteries, owing to its high theoretical capacity (1165 mAh g -1 ) and low potential (-2.714 V vs standard hydrogen electrode). However, the growth of sodium dendrites and the infinite volume change of metallic sodium during sodium striping/plating result in a low Coulombic efficiency and poor cycling stability, generating a safety hazard of sodium-based batteries. Here, an efficient approach was proposed to simultaneously generate an artificial SEI film and 3D host for metallic sodium based on a conversion reaction (CR) between sodium and MoS 2 (4Na + MoS 2 = 2Na 2 S + Mo) at room temperature. In the resultant sodium-MoS 2 hybrid after the conversion reaction (Na-MoS 2 (CR)), the production Na 2 S is homogeneously dispersed on the surface of metallic sodium, which can act as an artificial SEI film, efficiently preventing the growth of sodium dendrites; the residual MoS 2 nanosheets can construct a 3D host to confine metallic sodium, accommodating largely the volume change of sodium. Consequently, the Na-MoS 2 (CR) hybrid exhibits very low overpotential of 25 mV and a very long cycle stability more than 1000 cycles. This novel strategy is promising to promote the development of metal (lithium, sodium, zinc)-based electrodes.

Algal removal from cyanobacteria-rich waters by preoxidation-assisted coagulation-flotation: Effect of algogenic organic matter release on algal removal and trihalomethane formation.

PubMed

Lin, Jr-Lin; Hua, Lap-Cuong; Hung, Shih Kai; Huang, Chihpin

2018-01-01

The cyanobacteria-bloom in raw waters frequently causes an unpredictable chemical dosing of preoxidation and coagulation for an effective removal of algal cells in water treatment plants. This study investigated the effects of preoxidation with NaOCl and ClO 2 on the coagulation-flotation effectiveness in the removal of two commonly blooming cyanobacteria species, Microcystis aeruginosa (MA) and Cylindrospermopsis raciborskii (CR), and their corresponding trihalomethane (THM) formation potential. The results showed that dual dosing with NaOCl plus ClO 2 was more effective in enhancing the deformation of cyanobacterial cells compared to single dosing with NaOCl, especially for CR-rich water. Both preoxidation approaches for CR-rich water effectively reduced the CR cell count with less remained dissolved organic carbon (DOC), which benefited subsequent coagulation-flotation. However, preoxidation led to an adverse release of algogenic organic matter (AOM) in the case of MA-rich water. The release of AOM resulted in a poor removal in MA cells and a large amount of THM formation after oxidation-assisted coagulation-flotation process. The reduction in THM formation potential of CR-rich waters is responsible for effective algae and DOC removal by alum coagulation. It is concluded that the species-specific characteristic of cyanobacteria and their AOM released during chlorination significantly influences the performance of coagulation-flotation for AOM removal and corresponding THM formation. Copyright © 2017. Published by Elsevier B.V.

A Comparative Study on Macro- and Microelement Bioaccumulation Properties of Leaves and Bark of Quercus petraea and Pinus sylvestris.

PubMed

Klink, Agnieszka; Polechońska, Ludmiła; Dambiec, Małgorzata; Białas, Kamila

2018-01-01

Trees are widely used for biomonitoring and filtering air in industrial, urban, and rural areas. This research was undertaken to examine accumulation capacities of macroelements (Ca, K, Mg, Na) and trace metals (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in needles and bark of Pinus sylvestris and leaves and bark of Quercus petraea growing in the vicinity of the chlor-alkali plant PCC Rokita in Brzeg Dolny (Lower Silesia, SW Poland). Because Scots pine is well studied and considered a useful bioindicator, we have used this species as a base for comparison of the accumulation ability of sessile oak that shows some features of good bioindicator, but whose biogeochemistry was scarcely studied. Results showed that for both species leaves contained more macroelements (Ca, K, Mg), whereas the bark was richer in most trace metals (Cd, Cr, Cu, Fe, and Pb). However, trees studied differed with respect to element content. Oak bark and leaves were more effective in accumulating macro- and trace elements (bark Cd, Co, Cr, Cu, K, Mg, Mn, Na, Ni, Pb and leaves Ca, Cr, Cu, Fe, K, Mg, Na, Ni) than Scots pine tissues. Nevertheless, foliar metal accumulation index of these species was similar, suggesting that their overall ability to accumulate trace metals was similar.

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.

Mn-Cr isotopic systematics of Chainpur chondrules and bulk ordinary chondrites

NASA Technical Reports Server (NTRS)

Nyquist, L.; Lindstrom, D.; Wiesmann, H.; Bansal, B.; Shih, C.-Y.; Mittlefehldt, D.; Martinez, R.; Wentworth, S.

1994-01-01

We report on ongoing study of the Mn-Cr systematics of individual Chainpur (LL3.4) chondrules and compare the results to those for bulk ordinary chondrites. Twenty-eight chondrules were surveyed for abundances of Mn, Cr, Na, Fe, Sc, Hf, Ir, and Zn by INAA. Twelve were chosen for SEM/EDX and high-precision Cr-isotopic studies on the basis of LL-chondrite-normalized Mn(LL), Sc(LL), (Mn/Fe)(LL), and (Sc/Fe)(LL) as well as their Mn/Cr ratios. Classification into textural types follows from SEM/EDX examination of interior surfaces.

Effects of SO42- ions on the corrosion of GH3535 weld joint in FLiNaK molten salt

NASA Astrophysics Data System (ADS)

Zhu, Yasheng; Qiu, Jie; Hou, Juan; Liu, Wenguan; Chen, Huaican; Ai, Hua; Yu, Guojun; Wang, Jianqiang; Zhou, Xingtai

2017-08-01

The present work studied the impact of SO42- ions on the corrosion behaviors of GH3535 weld joint in FLiNaK molten salt. The concentration of SO42- ions in the FLiNaK molten salt was controlled by adjusting the quantity of Na2SO4 added into the salt. Results indicate that the SO42- ions in the FLiNaK salt speed up the corrosion rate remarkably by promoting the dissolution of Cr from the alloy matrix into the salt. With the concentration of SO42- ions in the FLiNaK salt increases from 100 ppm to 1000 ppm, the weight losses and the Cr depletion layer depths of the corroded specimens increase linearly. Even in the case of the heavy corrosion attack caused by the SO42- ions, the corrosion performance is similar between the base zone and fusion zone in the GH3535 weld joint. It is demonstrated that the structural diversity caused by the welding process has little impact on the corrosion performances of GH3535 alloy in FLiNaK molten salt.

In-stent neoatherosclerosis and tissue characteristics of restenotic lesions following implantation of second generation drug-eluting stents in unrestricted coronary lesions: Optical frequency domain imaging study.

PubMed

Sabbah, Mahmoud; Kadota, Kazushige; El-Eraky, Azza; Kamal, Hanan M; Abdellah, Ahmed-Tageldien; El Hawary, Ahmed

2017-06-01

Differences in stent platform, polymer coatings, and antirestenotic drugs among the current in use second-generation drug-eluting stents (G2-DESs) may induce significant variations in neointimal response and vascular healing, which may impact the prevalence of neoatherosclerosis (NA) and morphological appearance of the restenotic tissue. Utilizing Optical frequency domain imaging, two independent reviewers, retrospectively compared the prevalence of neoatherosclerosis (NA), and the morphological differences, and tissue characteristics of 50 G2-DESs in-stent restenosis (ISR) lesions (35 everolimus-eluting stent [22 cobalt-chromium (CoCr), 13 platinum-chromium (PtCr)], and 15 biolimus-eluting stent [BES]) implanted liberally in unrestricted coronary lesions. More than half of the stents were implanted in type C lesions, while 40% of the stents were implanted primarily in lesions with recanalized chronic total occlusion. NA, defined as a neointima formation with the presence of lipids or calcification, was observed in fewer than half (24/50) of all ISR lesions with no significant in-between group differences (41%, 69%, and 40% in CoCr, PtCr, and BES respectively, P = 0.22), nor were there any significant differences in the morphological appearance or tissue characteristics between all G2-DESs subtypes. Acknowledging some limitations, our results may suggest that the prevalence of NA and the morphological appearance of restenotic lesions might not differ when G2-DESs are implanted in unrestricted, rather complex, coronary lesions. © 2017, Wiley Periodicals, Inc.

Thiocyanate-Ligated Heterobimetallic {PtM} Lantern Complexes Including a Ferromagnetically Coupled 1D Coordination Polymer.

PubMed

Guillet, Jesse L; Bhowmick, Indrani; Shores, Matthew P; Daley, Christopher J A; Gembicky, Milan; Golen, James A; Rheingold, Arnold L; Doerrer, Linda H

2016-08-15

A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K.

New calibration of Ji - Di clinopyroxene barometer for Eclogites, pyroxenites and peridotites and eclogite - pyroxenite mantle geotherms.

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor; Vishnyakova, Elena

2010-05-01

Checking the universe clinopyroxene JD-Di barometer on the experimental system showed that it better to use the separate schemes for the eclogite and peridotite systems. The clinopyroxene barometer based on the internal exchange of Jd-Di components for the Al. It allow using the temperature calculated with the (Krogh, 1988) method for the The barometer was calibrated on the 200 experimental runs for the eclogitic system (Yaxley,Brey,2004; Spandler ea, 2008; Konzett ea, 2008; Hanrahan ea, 2009 and references there in). It reproduces the pressure range to 120 kbar with the r= 0.91 (S=8) for 180 experimental runs. P(Ash2010 Ecl)=0.32 (1-0.215*Na/Al+0.012*Fe/Na)*Kd^3/4*ToK/(1+Fe)*(1+5*Fe)- 35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-xx(2,8))*10+xx(2,9)/xx(2,3)* ToK /200-1.5 P1=(0.00004*P^3-0.0091*P^2+1.3936*P)*1.05 Where KD = Na*Mg/xAlCr*/Ca; XAlCr= Al+Cr+4*Ti-K-(Fe-0.21)*0.75 The tests on the natural associations form the eclogitic xenoliths with and without the diamonds and omphacite diamond inclusions (Taylor ea, 2006; Shatsky ea, 2008; Jacob ea, 2009) have shown very good agreement with the position of the Graphite -Diamond (Kennedy, Kennedy, 1977) boundary and to the conductive geotherms which are close to 34-36mvm-2 geotherms while for the South Africa they are more close to 40mvm-2 geotherms. For the zonal omphacites it produces the range of the nearly equal pressures or more rarely advective paths. The levels of the maximum enrichments in eclogites which are close to 50-60 kabr beneath 360ma Siberian kimberlites coincides with the levels of heating according to the monomineral and polymineral thermobarometry. South Africa eclogite geotherms often split into 2-3 branches: subductional (35) conductive (40) for Paleozoic-Mesozoic mantle lithosphere and the hottest advective close o 45 mv/m-2. For the pyroxenite compositions the barometer was rearranged to by the adding the temperature influence on Al , Ta, Fe exactly in KD as following: P(Ash2010 Per-Pxt)=0.275*(1-0.17*Na/Al+0.0115*Fe/Na)*Kd^3/4*ToK/(1+Fe)* (1+5*Fe*(ToK-600)/50)-35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-xx(2,8))*10+xx(2,9)/xx(2,3)* ToK /300-4*(Fe*33.2-4) -(Al-5.5)*( ToK -1300)/70-( ToK -1200)*0.015 with the second correction P=P*0.65+10+Mg*Al*( ToK -1400)/500 Where KD = Na*Mg/xAlCr*/Ca; XAlCr= Al*((T0-800)/800)**0.25+Cr-K+(4*Ti-0.0125)/(T0-600)*400+(Fe-0.21)*(T0-600)/14000 This equations reproduces the experimental pressures for 300 experimental runs with the R=0.84 and for the best set of the experimental data (Walter, 1999; Taylor ea 1998; Brey Kohler, 1990; 2009) with the E=0.95 (s=7) within the 100 kbar interval. They allow to work with the wide range of the pyroxenite compositions giving the practically coinciding PT parameters with the pressures determined for ilmenites and chromites as well as the (Brey, Kohler, 1900) pressure estimates. The PT parameters reconstructed for the mantle lithosphere beneath > 120 pipes from Yakutia , Baltica, Africa , North America and other world wide kimberlites have shown very good coincidence with the estimates from the other methods of monomineral (Nimis, Taylor, 2000; McGregor, 1974; Ashchepkov ea. 2009 ) and Gar-Opx barometers (Brey, Kohler, 1900; Nickel, Green, 1975). For the garnet and spinel xenoliths of the alkali basalts representing fertile or regenerated peridotites with high Al content of the clinopyroxenes the modified equation allows to determine the pressures together for megacrysts, pyroxeniets and peridotites using the following equation P=0.035*Kd*ToK)/(1+3.5*Fe)- 50*ln(1273/(ToK-100)*(Al+5*Na-Ti+2*Cr) -(Na-0.050)*(ToK-1200)*(Ca-0.85)/7000+5 Where KD = Na*Mg/xAlCr*/Ca; xAlCr= (Al+Si-2)*((ToK-700)/900)^0.35+Cr+Fe3-K +(4*Ti-0.0125)/(ToK-600)*700 +(Fe-0.21)*(ToK-400)/17000 This equations also very good reproduce the experimental runs in the pressure interval from 10 to 80 kbar but better to 50 kbars (R=0.92) (S=5) for 170 experimental runs (Putirka ea, 1996; Fallon ea, 1999; Taylor ea, 1998; Drapper Green, 1997; Lambart ea 2009) in this pressure range.

Adalimumab Treatment in Biologically Naïve Crohn's Disease: Relationship with Ectopic MUC5AC Expression and Endoscopic Improvement

PubMed Central

Mizoshita, Tsutomu; Tanida, Satoshi; Tsukamoto, Hironobu; Ozeki, Keiji; Katano, Takahito; Nishiwaki, Hirotaka; Ebi, Masahide; Mori, Yoshinori; Kubota, Eiji; Kataoka, Hiromi; Kamiya, Takeshi; Joh, Takashi

2014-01-01

Background. Adalimumab (ADA) is effective for patients with Crohn's disease (CD). However, there have been few reports on ADA therapy with respect to its relationship with pathologic findings and drug efficacy in biologically naïve CD cases. Methods. Fifteen patients with active biologically naïve CD were treated with ADA. We examined them clinically and pathologically with ectopic MUC5AC expression in the lesions before and after 12 and 52 weeks of ADA therapy, retrospectively. Results. Both mean CD activity index scores and serum C-reactive protein values were significantly lower after ADA therapy (P < 0.001). In the MUC5AC negative group, all cases exhibited clinical remission (CR) and endoscopic improvement at 52 weeks. In MUC5AC positive groups, loss of MUC5AC expression was detected in cases having CR and endoscopic improvement at 52 weeks, while remnant ectopic MUC5AC expression was observed in those exhibiting no endoscopic improvement and flare up after 52 weeks. Conclusions. ADA leads to CR and endoscopic improvement in biologically naïve CD cases. In addition, ectopic MUC5AC expression may be a predictive marker of flare up and endoscopic improvement in the intestines of CD patients. PMID:24829572

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi 2 and CoCrFeNi 2 Mo 0.25 under Sodium Chloride Aqueous Conditions

DOE PAGES

Rodriguez, Alvaro A.; Tylczak, Joseph H.; Gao, Michael C.; ...

2018-01-01

The corrosion behavior of high-entropy alloys (HEAs) CoCrFeNi 2 and CoCrFeNi 2 Mo 0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl) at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276) and stainless steel 316L (UNS 31600) to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pittingmore » corrosion. Cyclic voltammetry (CV) can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS) elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM) analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi 2 Mo 0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi 2 and stainless steel 316L.« less

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi 2 and CoCrFeNi 2 Mo 0.25 under Sodium Chloride Aqueous Conditions

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

Rodriguez, Alvaro A.; Tylczak, Joseph H.; Gao, Michael C.

The corrosion behavior of high-entropy alloys (HEAs) CoCrFeNi 2 and CoCrFeNi 2 Mo 0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl) at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276) and stainless steel 316L (UNS 31600) to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pittingmore » corrosion. Cyclic voltammetry (CV) can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS) elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM) analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi 2 Mo 0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi 2 and stainless steel 316L.« less

Platelet aggregation caused by a partially purified jellyfish toxin from Carybdea rastonii.

PubMed

Azuma, H; Sekizaki, S; Satoh, A; Nakajima, T; Ishikawa, M

1986-01-01

A partially purified toxin (pCrTX) was obtained from the tentacles of the jellyfish, Carybdea rastonii. When pCrTX (3 X 10(-8) - 3 X 10(-7) g/ml) was added to citrated platelet-rich plasma, aggregation was produced in a concentration-dependent manner. Scanning electron microscopic examination revealed that both pCrTX and collagen produced aggregates of platelets possessing many pseudopods. The concentration which produced 50% aggregation for pCrTX was 1.8 X 10(-7) g/ml, as compared to 2.3 X 10(-6) g/ml for collagen. The pCrTX-induced aggregation was only slightly inhibited by indomethacin and quinacrine in concentrations sufficient to inhibit arachidonic acid- and collagen-induced aggregation. pCrTX was less active in washed platelets suspended in Ca2+ free medium, whereas the pCrTX-induced aggregation was significantly augmented in the presence of Ca2+. The augmentation of aggregation by Ca2+ was only slightly attenuated by pretreatment with 100 microM verapamil. pCrTX significantly increased the concentration of cytoplasmic free Ca2+ ([Ca2+]i) and depolarized the platelet membrane in concentrations that produced aggregation. The increase in [Ca2+]i caused by pCrTX was little affected by verapamil. The depolarization by pCrTX was unchanged in the presence or absence of Ca2+, or by sodium or potassium transport inhibitors. The movement of 22Na+ into platelets was significantly increased by pCrTX. This increase in the movement of 22N+ into platelets was unaffected by tetrodotoxin. On the other hand, pCrTX-induced aggregation, depolarization and the increase in [Ca2+]i were all significantly attenuated in low Na+ medium. These results suggest that pCrTX causes a massive depolarization by increasing cation permeability indiscriminately and this generalized depolarization permits an inward movement of calcium down an electrochemical gradient which, in turn triggers platelet aggregation.

Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey

PubMed Central

Huang, Lihui; Yu, Chang Ho; Hopke, Philip K.; Lioy, Paul J.; Buckley, Brian T.; Shin, Jin Young; Fan, Zhihua (Tina)

2015-01-01

Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na2CO3-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m3. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM10 collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05–1.41 ng/m3 in the winter and 0.99–1.56 ng/m3 in the summer. The soluble Cr(VI) concentrations were 0.03–0.19 ng/m3 in the winter and 0.12–0.37 ng/m3 in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3–43.7%, significantly higher than 4.2–14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer. PMID:26120324

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

Study of the effects of gaseous environments on sulfidation attack of superalloys

NASA Technical Reports Server (NTRS)

Smeggil, J. G.; Bornstein, N. S.

1977-01-01

Studies were conducted to examine the effect of the gaseous corrodents NaCl, HCl, and NaOH on the high temperature oxidation and Na2SO4-induced corrosion behavior of the alumina former NiAl, the chromia former Ni-25 wt.% Cr, elemental Cr, and the superalloy B-1900. Experiments were conducted at 900 and 1050 C in air in the presence and absence of the gaseous corrodents. Effects involving both reaction rates and microstructural changes in oxide morphology were observed due to the presence of these corrodents at levels anticipated to be present in operating industrial and marine gas turbines. The effect of gaseous NaCl, HCl, and possibly NaOH on NiAl in simple oxidation was to remove aluminum from below the protective alumina layer and to simultaneously weaken the adherence of the protective alumina oxide scale to the substrate. The aluminum removed from below the oxide scale was redeposited on its surface as alpha-Al2O3 whiskers. With respect to the chromia formers, gaseous NaCl and HCl promoted breakaway oxidation kinetics and changes in the microstructures of the oxide scales.

Pilot scale treatment of chromite ore processing residue using sodium sulfide in single reduction and coupled reduction/stabilization processes.

PubMed

Velasco, Antonio; Ramírez, Martha; Hernández, Sergio; Schmidt, Winfried; Revah, Sergio

2012-03-15

Single Cr(VI) reduction and coupled reduction/stabilization (R/S) processes were evaluated at pilot scale to determine their effectiveness to treat chromite ore processing residue (COPR). Sodium sulfide was used as the reducing agent and cement, gypsum and lime were tested as the stabilizing agents. The pilot experiments were performed in a helical ribbon blender mixer with batches of 250 kg of COPR and mixing time up to 30 min. Na2S/Cr(VI) mass ratios of 4.6, 5.7 and 6.8 were evaluated in the single reduction process to treat COPR with Cr(VI) concentration of ≈4.2 g/kg. The R/S process was tested with a Na2S/Cr(VI) mass ratio of 5.7 and including stabilizing agents not exceeding 5% (w/w(COPR)), to treat COPR with a Cr(VI) content of ≈5.1g/kg. The single reduction process with a ratio of 6.8, reached Cr(VI) reduction efficiencies up to 97.6% in the first days, however these values decreased to around 93% after 380 days of storage. At this point the total Cr level was around 12.5 mg/L. Cr(VI) removal efficiencies exceeding 96.5% were reached and maintained during 380 days when the coupled R/S process was evaluated. Total Cr levels lower than 5 mg/l were attained at the initials days in all R/S batch tested, however after 380 days, concentrations below the regulatory limit were only found with gypsum (2%) as single agent and with a blend of cement (4%) and lime (1%). These results indicated that the coupled R/S process is an excellent alternative to stabilize COPR. Copyright © 2011 Elsevier B.V. All rights reserved.

Nickel-plating for active metal dissolution resistance in molten fluoride salts

NASA Astrophysics Data System (ADS)

Olson, Luke; Sridharan, Kumar; Anderson, Mark; Allen, Todd

2011-04-01

Ni electroplating of Incoloy-800H was investigated with the goal of mitigating Cr dissolution from this alloy into molten 46.5%LiF-11.5%NaF-42%KF eutectic salt, commonly referred to as FLiNaK. Tests were conducted in graphite crucibles at a molten salt temperature of 850 °C. The crucible material graphite accelerates the corrosion process due to the large activity difference between the graphite and the alloy. For the purposes of providing a baseline for this study, un-plated Incoloy-800H and a nearly pure Ni-alloy, Ni-201 were also tested. Results indicate that Ni-plating has the potential to significantly improve the corrosion resistance of Incoloy-800H in molten fluoride salts. Diffusion of Cr from the alloy through the Ni-plating does occur and if the Ni-plating is thin enough this Cr eventually dissolves into the molten salt. The post-corrosion test microstructure of the Ni-plating, particularly void formation was also observed to depend on the plating thickness. Diffusion anneals in a helium environment of Ni-plated Incoloy-800H and an Fe-Ni-Cr model alloy were also investigated to understand Cr diffusion through the Ni-plating. Further enhancements in the efficacy of the Ni-plating as a protective barrier against Cr dissolution from the alloy into molten fluoride salts can be achieved by thermally forming a Cr 2O 3 barrier film on the surface of the alloy prior to Ni electroplating.

A high sodium intake reduces antiproteinuric response to renin-angiotensin-aldosterone system blockade in kidney transplant recipients.

PubMed

Monfá, Elena; Rodrigo, Emilio; Belmar, Lara; Sango, Cristina; Moussa, Fozi; Ruiz San Millán, Juan Carlos; Piñera, Celestino; Fernández-Fresnedo, Gema; Arias, Manuel

Post-transplant proteinuria is associated with lower graft and patient survival. Renin-angiotensin-aldosterone system blockers are used to reduce proteinuria and improve renal outcome. Although it is known that a high salt intake blunts the antiproteinuric effect of ACEI and ARB drugs in non-transplant patients, this effect has not been studied in kidney transplant recipients. To analyse the relationship between sodium intake and the antiproteinuric effect of ACEI/ARB drugs in kidney transplant recipients. We selected 103 kidney transplant recipients receiving ACEI/ARB drugs for more than 6 months due to proteinuria>1 g/day. Proteinuria was analysed at baseline and at 6 months after starting ACEI/ARB treatment. Salt intake was estimated by urinary sodium to creatinine ratio (uNa/Cr). Proteinuria fell to less than 1g/day in 46 patients (44.7%). High uNa/Cr was associated with a smaller proteinuria decrease (r=-0.251, P=.011). The percentage proteinuria reduction was significantly lower in patients in the highest uNa/Cr tertile [63.9% (IQR 47.1%), 60.1% (IQR 55.4%), 38.9% (IQR 85.5%), P=.047]. High uNa/Cr independently relates (OR 2.406 per 100 mEq/g, 95% CI: 1.008-5.745, P=.048) to an antiproteinuric response <50% after renin-angiotensin-aldosterone system blockade. A high salt intake results in a smaller proteinuria decrease in kidney transplant recipients with proteinuria treated with ACEI/ARB drugs. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

Hydrous Na-garnet from Garnet Ridge; products of mantle metasomatism underneath the Colorado Plateau

NASA Astrophysics Data System (ADS)

Sakamaki, Kunihiko; Sato, Yuto; Ogasawara, Yoshihide

2016-12-01

This is the first report on amphibole exsolution in pyrope from the Colorado Plateau. Pyrope crystals delivered from mantle depths underneath the Colorado Plateau by kimberlitic volcanism at 30 Ma were collected at Garnet Ridge, northern Arizona. The garnet grains analyzed in this study occur as discrete crystals (without adjacent rock matrix) and are classified into two major groups, Cr-rich pyrope and Cr-poor pyrope. The Cr-poor pyrope group is divided into four subgroups based on exsolved phases: amphibole lamella type, ilmenite lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type. Exsolved amphibole occurs in amphibole lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type of Cr-poor pyrope. The amphibole crystals tend to have preferred orientations in their garnet hosts and occur as monomineralic hexagonal or rhombic prisms and tablets, and as multimineralic needles or blades with other exsolved phases. Exsolved amphibole has pargasitic compositions (Na2O up to 1.6 apfu based on 23 oxygen). Garnet host crystals that have undergone amphibole exsolution have low OH contents (2-42 ppmw H2O) compared to garnets that do not have amphibole lamellae (up to 115 ppmw H2O). The low OH contents of garnets hosting amphibole lamellae suggest loss of OH from garnet during amphibole exsolution. Amphibole exsolution from pyrope resulted from breakdown of a precursor "hydrous Na-garnet" composition (Mg,Na+ x)3(Al2 - x, Mgx)2Si3O12 - 2x(OH)2x. Exsolution of amphibole and other phases probably occurred during exhumation to depths shallower than 100 km prior to volcanic eruption.

Chromium precipitation from tanning spent liquors using industrial alkaline residues: A comparative study

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

Fonseca Almeida, M.A.; Boaventura, R.A.R.

1998-07-01

Chromium precipitation from spent tanning liquors using industrial alkaline tailings is described and removal efficiencies are compared with those obtained with traditional chemicals as NaOH, CaO and MgO: (1) using steelmaking dusts at dosages up to 70 g/l residual Cr remains {ge} 3.7 mg/l. Moreover Cr and mainly Pb are partially leached by the spent tanning liquor, therefore limiting the use of this industrial residue as Cr precipitant; (2) a dosage of 80 g/l (dry basis) of chemical sludge from a water treatment plant results in a removal efficiency of 99.97% Cr and residual Cr {le} 2 mg/l under experimentalmore » conditions that include stirring at 100 rpm for 1 h and settling for 23 h. Sedimentation time may be reduced to 2 h if stirring is extended to 2 h. Resulting sludge volume is about 400 ml/l. However, during Cr precipitation, Al is leached form the added product up to about 40 mg Al per liter of supernatant; (3) precipitation using acetylene production sludge only requires a dosage of 16 g/l (dry basis) to remove 99.96% Cr after stirring for 1 h and settling for 2 h. The soluble Cr concentration in the clarified effluent is {le} 2 mg/l and the sludge volume about 500 ml/l. This Cr level can also be achieved at a dosage of 14 g/l, provided the stirring time is increased to 3 h; (4) these results are comparable with those using either CaO or MgO at similar dosages; and (5) NaOH at dosages between 6.4 and 14 g/l proved to be not sufficiently effective for Cr precipitation. Although removal efficiencies up to 99.9% are achieved, residual Cr is always above 8.7 mg/l. Additionally, the resulting sludge is not very dense, thus leading to high sludge volume production.« less

Prostate Cancer Cells in Different Androgen Receptor Status Employ Different Leucine Transporters.

PubMed

Otsuki, Hideo; Kimura, Toru; Yamaga, Takashi; Kosaka, Takeo; Suehiro, Jun-Ichi; Sakurai, Hiroyuki

2017-02-01

Leucine stimulates cancer cell proliferation through the mTOR pathway, therefore, inhibiting leucine transporters may be a novel therapeutic target for cancer. L-type amino acid transporter (LAT) 1, a Na + -independent amino acid transporter, is highly expressed in many tumor cells. However, leucine transporter(s) in different stages of prostate cancer, particularly in the stages of castration resistance with androgen receptor (AR) expression, is unclear. LNCaP and DU145 and PC-3 cell lines were used as a model of androgen dependent, and metastatic prostate cancer. A new "LN-cr" cell line was established after culturing LNCaP cells for 6 months under androgen-free conditions, which is considered a model of castration resistant prostate cancer (CRPC) with androgen AR expression. The expression of leucine transporters was investigated with quantitative PCR and immunofluorescence. Uptake of 14 C Leucine was examined in the presence or absence of BCH (a pan-LAT inhibitor), JPH203 (an LAT1-specific inhibitor), or Na + . Cell growth was assessed with MTT assay. siRNA studies were performed to evaluate the indispensability of y + LAT2 on leucine uptake and cell viability in LN-cr. Cell viability showed a 90% decrease in the absence of leucine in all four cell lines. LNCaP cells principally expressed LAT3, and their leucine uptake was more than 90% Na + -independent. BCH, but not JPH203, inhibited leucine uptake, and cell proliferation (IC 50BCH :15 mM). DU145 and PC-3 cells predominantly expressed LAT1. Leucine uptake and cell growth were suppressed by BCH or JPH203 in a dose-dependent manner (IC 50BCH : ∼20 mM, IC 50JPH203 : ∼5 µM). In LN-cr cells, Na + -dependent uptake of leucine was 3.8 pmol/mgprotein/min, while, Na + -independent uptake was only 0.52 (P < 0.05). Leucine uptake of LN-cr was largely (∼85%) Na + -dependent. y + LAT2 expression was confirmed in LN-cr. Knockdown of y + LAT2 lead to significant leucine uptake inhibition (40%) and cell growth inhibition (20%). New CRPC cell line with increased expression of y + LAT2 as a leucine transporter was established in vitro. Anti-leucine transporter therapy could be an important option against prostate cancer. Prostate 77:222-233, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

40 CFR 63.11412 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... ore from trivalent to hexavalent chromium. Sodium chromate means Na2CrO4. It is produced by roasting...: Chromium Compounds Other Requirements and Information § 63.11412 What definitions apply to this subpart... matter loadings. Chromic acid means chromium trioxide (CrO3). It is produced by the electrolytic reaction...

40 CFR 63.11412 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... ore from trivalent to hexavalent chromium. Sodium chromate means Na2CrO4. It is produced by roasting...: Chromium Compounds Other Requirements and Information § 63.11412 What definitions apply to this subpart... matter loadings. Chromic acid means chromium trioxide (CrO3). It is produced by the electrolytic reaction...

40 CFR 63.11412 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... ore from trivalent to hexavalent chromium. Sodium chromate means Na2CrO4. It is produced by roasting...: Chromium Compounds Other Requirements and Information § 63.11412 What definitions apply to this subpart... matter loadings. Chromic acid means chromium trioxide (CrO3). It is produced by the electrolytic reaction...

New series of triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) with framework structures and mobile silver ion sublattices

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

Kotova, Irina Yu.; Buryat State University, Smolin St. 24a, Ulan-Ude 670000, Buryat Republic; Solodovnikov, Sergey F.

Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized and single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown. In their structures, the MoO{sub 4} tetrahedra, pairs and trimers of edge-shared (Mg, R)O{sub 6} octahedra are connected by common vertices to form a 3D framework. Large framework cavities involve Ag{sup +} cations disordered on three nearby positions with CN=3+1 or 4+1. Alternating (Mg, R)O{sub 6} octahedra and MoO{sub 4} tetrahedra in the framework form quadrangular windows penetrable for Ag{sup +} at elevated temperatures.more » Above 653–673 K, the newly obtained molybdates demonstrate abrupt reduction of the activation energy to 0.4–0.6 eV. At 773 K, AgMg{sub 3}Al(MoO{sub 4}){sub 5} shows electric conductivity 2.5·10{sup −2} S/cm and E{sub a}=0.39 eV compatible with characteristics of the best ionic conductors of the NASICON type. - Graphical abstract: Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized, AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were structurally characterized, ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} were measured. Display Omitted - Highlights: • Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized. • Single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown and their crystal structures were determined. • Disordering Ag{sup +} ions and penetrable framework structures of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) suggest 2D-character of silver-ion mobility. • Measured ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} are compatible with characteristics of the best ionic conductors of the NASICON type.« less

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.

Diazo dye Congo Red degradation using a Boron-doped diamond anode: An experimental study on the effect of supporting electrolytes.

PubMed

Jalife-Jacobo, H; Feria-Reyes, R; Serrano-Torres, O; Gutiérrez-Granados, S; Peralta-Hernández, Juan M

2016-12-05

Diazo dye Congo Red (CR) solutions at 100mg/L, were degraded using different supporting electrolytes in an electrochemical advanced oxidation process (EAOPs), like the anodic oxidation (AOx/BDD). All experiments were carried out in a 3L flow reactor with a Boron-doped diamond (BDD) anode and stainless steel cathode (AISI 304), at 7.5, 15, 30 and 50mA/cm(2) current densities (j). Furthermore, each experiment was carried out under a flow rate of 7L/min. Additionally, HClO4, NaCl, Na2SO4, and H2SO4 were tested as supporting electrolytes at a 50mM concentration. The degradation process was at all times considerably faster in NaCl medium. Solutions containing SO4(2-) or ClO4(-) ions were less prompted to degradation due to the low oxidation power of these species into the bulk. Dissolved organic carbon (DOC) analysis, was carried out to evaluate the mineralization of CR. The degradation of CR, was evaluated with the HPLC analysis of the treated solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Geographical Variation in Prevalence of Cryptococcal Antigenemia among HIV-infected Treatment-Naïve Patients in Nigeria: A multicenter cross-sectional study

PubMed Central

Ezeanolue, Echezona E.; Nwizu, Chidi; Greene, Gregory S.; Amusu, Olatilewa; Chukwuka, Chinwe; Ndembi, Nicaise; Smith, Rachel M.; Chiller, Tom; Pharr, Jennifer; Kozel, Thomas R

2016-01-01

Objective Worldwide, HIV-associated cryptococcal meningitis affects approximately 1 million persons and causes 600,000 deaths each year mostly in sub-Sharan Africa. Limited data exist on cryptococcal meningitis and antigenemia in Nigeria, and most studies are geographically restricted. We determined the prevalence of cryptococcal antigenemia (CrAg) among HIV-infected treatment-naïve individuals in Nigeria. Design/Methods This was a retrospective, cross-sectional study across four geographic regions in Nigeria. We performed CrAg testing using a lateral flow immunoassay on archived whole blood samples collected from HIV-infected participants at US PEPFAR-supported sites selected to represent the major geographical and ethnic diversity in Nigeria. Eligible samples were (1) stored in an -80° freezer; (2) collected from consenting patients (>15 years) naïve to antiretroviral therapy with CD4+ count less than 200 cells/mm3. Results A total of 2,752 stored blood samples were retrospectively screened for CrAg. A majority of samples were from participants aged 30 - 44 (57.6%), and 1,570 (57.1%) were from women. The prevalence of CrAg positivity in specimens with CD4 < 200 cells/mm3 was 2.3% (95% CI = 1.8%-3.0%), and varied significantly across the four regions (p < 0.001). At 4.4% (3.2%-5.9%), the South East contained the highest prevalence. Conclusion The significant regional variation in CrAg prevalence found in Nigeria should be taken into consideration as plans are made to integrate routine screening into clinical care for HIV-infected patients. PMID:27144527

Efficacy of low concentrations of sodium hypochlorite and low-powered Er,Cr:YSGG laser activated irrigation against an Enterococcus faecalis biofilm.

PubMed

Christo, J E; Zilm, P S; Sullivan, T; Cathro, P R

2016-03-01

To establish the antibacterial efficacy of low concentrations of sodium hypochlorite with and without Er,Cr:YSGG laser activation on Enterococcus faecalis biofilms in extracted teeth. The root canals of 96 decoronated single-rooted extracted human teeth were prepared to a size 40, 0.06 taper 1 mm beyond the apex. They were mounted within a flow cell, which was sterilized before pumping a nutrient media through the root canals. The flow cell was inoculated with E. faecalis (ATCC 700802) and cultivated for 4 weeks. The root-ends were sealed, and the roots were then subjected to one of six treatment groups: group 1: syringe irrigation (SI) with saline (control) using a 27 -gauge Monoject needle 1 mm from the apex for 2 min; group 2: as for group 1 but with 1% NaOCl; group 3: as for group 1 but with 4% NaOCl; group 4: 0.5% NaOCl irrigation for 15 s followed by laser-activated irrigation (LAI) with four 15-s cycles replenishing the irrigant between cycles; group 5: as for group 4 but with 1% NaOCl as the irrigant; group 6: as for group 4 but with 4% NaOCl as the irrigant. Following treatment, teeth were crushed and viable bacteria were quantitated by serial dilution and plating. The colony-forming unit values were compared between groups using one-way anova and Tukey-adjusted post hoc tests. A two-tailed P value of <0.05 was considered statistically significant. The mean number of cells recovered from the 1% NaOCl SI group was significantly higher than that from the 4% NaOCl LAI group (P = 0.02). Within the limitations of this laboratory study, low-powered (0.5 W) Er,Cr:YSGG laser activation did not improve the antibacterial effect of low concentrations of sodium hypochlorite. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Investigation of structural stability and elastic properties of CrH and MnH: A first principles study

NASA Astrophysics Data System (ADS)

Kanagaprabha, S.; Rajeswarapalanichamy, R.; Sudhapriyanga, G.; Murugan, A.; Santhosh, M.; Iyakutti, K.

2015-06-01

The structural and mechanical properties of CrH and MnH are investigated using first principles calculation based on density functional theory as implemented in VASP code with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and other theoretical results. A structural phase transition from NaCl to NiAs phase at a pressure of 76 GPa is predicted for both CrH and MnH.

Adsorption mechanisms of metal ions on the potassium dihydrogen phosphate (1 0 0) surface: A density functional theory-based investigation.

PubMed

Wu, Yulin; Zhang, Lei; Liu, Yao; Qu, Yunpeng

2018-07-15

The adsorption of metal ions (K + , Na + , Ca 2+ , Cu 2+ , Al 3+ , Cr 3+ ) on the (1 0 0) surface of potassium dihydrogen phosphate (KDP) has been studied using density functional theory (DFT). Calculation results show that all the investigated metal ions can be spontaneously adsorbed on the surface with negative adsorption energies. The adsorption stability increases in the order of Na +  < K +  < Cu 2+  < Ca 2+  < Al 3+  < Cr 3+ , and shows a consistent trend as the adsorbed metal ion valence (monovalent < divalent < trivalent). Three types of stable adsorption configurations are observed, corresponding to three different bonding mechanisms. Na + , K + and Ca 2+ ions with a large radius can form two ionic bonds and one weak covalent bond with the O and H atoms respectively. In addition, the medium-sized ion of Cu 2+ forms two covalent bonds with the O and H atoms. Furthermore, Al 3+ and Cr 3+ ions with the smallest radius form two metal-oxygen and one metal-hydrogen covalent bonds with the surface, making one H-O bond broken. Compared with other metal ions, Al 3+ and Cr 3+ have the strongest interactions with the surface, which can be explained by the significant electron transfer and more stable covalent bond formations between these two ions and the surface. Copyright © 2018 Elsevier Inc. All rights reserved.

Remediation of Pb/Cr co-contaminated soil using electrokinetic process and approaching electrode technique.

PubMed

Ng, Yee-Sern; Sen Gupta, Bhaskar; Hashim, Mohd Ali

2016-01-01

Electrokinetic process has emerged as an important tool for remediating heavy metal-contaminated soil. The process can concentrate heavy metals into smaller soil volume even in the absence of hydraulic flow. This makes it an attractive soil pre-treatment method before other remediation techniques are applied such that the chemical consumption in the latter stage can be reduced. The present study evaluates the feasibility of electrokinetic process in concentrating lead (Pb) and chromium (Cr) in a co-contaminated soil using different types of wetting agents, namely 0.01 M NaNO3, 0.1 M citric acid and 0.1 M EDTA. The data obtained showed that NaNO3 and citric acid resulted in poor Pb electromigration in this study. As for Cr migration, these agents were also found to give lower electromigration rate especially at low pH region as a result of Cr(VI) adsorption and possible reduction into Cr(III). In contrast, EDTA emerged as the best wetting agent in this study as it formed water-soluble anionic complexes with both Pb and Cr. This provided effective one-way electromigration towards the anode for both ions, and they were accumulated into smaller soil volume with an enrichment ratio of 1.55-1.82. A further study on the application of approaching cathode in EDTA test showed that soil alkalisation was achieved, but this did not provide significant enhancement on electromigration for Pb and Cr. Nevertheless, the power consumption for electrokinetic process was decreased by 22.5%.

Na7Cr4(P2O7)4PO4

PubMed Central

Bourguiba Fakhar, Noura; Zid, Mohamed Faouzi; Driss, Ahmed

2013-01-01

The title compound, hepta­sodium tetra­chromium(III) tetra­kis­(diphosphate) orthophosphate, was synthesized by solid-state reaction. Its structure is isotypic with that of Na7 M 4(P2O7)4PO4 (M = In, Al) compounds and is made up from a three-dimensional [(CrP2O7)4PO4]7− framework with channels running along [001]. The three Na+ cations are located in the voids of the framework. One of the cations is situated on a general position, one is equally disordered around a twofold rotation axis and one is on a fourfold rotoinversion axis. The isolated PO4 tetra­hedron of the anionic framework is also situated on the -4 axis. Structural relationships between the title compound and different diphosphates containing MP2O11 units (M = Mo, V) are discussed. PMID:23723751

An isopiestic study of aqueous NaBr and KBr at 50 °C: Chemical equilibrium model of solution behavior and solubility in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems to high concentration and temperature

NASA Astrophysics Data System (ADS)

Christov, Christomir

2007-07-01

The isopiestic method has been used to determine the osmotic coefficients of the binary solutions NaBr-H 2O (from 0.745 to 5.953 mol kg -1) and KBr-H 2O (from 0.741 to 5.683 mol kg -1) at the temperature t = 50 °C. Sodium chloride solutions have been used as isopiestic reference standards. The isopiestic results obtained have been combined with all other experimental thermodynamic quantities available in literature (osmotic coefficients, water activities, bromide mineral's solubilities) to construct a chemical model that calculates solute and solvent activities and solid-liquid equilibria in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems from dilute to high solution concentration within the 0-300 °C temperature range. The Harvie and Weare [Harvie C., and Weare J. (1980) The prediction of mineral solubilities in naturalwaters: the Na-K-Mg-Ca-Cl-SO 4-H 2O system from zero to high concentration at 25 °C. Geochim. Cosmochim. Acta44, 981-997] solubility modeling approach, incorporating their implementation of the concentration-dependent specific interaction equations of Pitzer [Pitzer K. (1973) Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem.77, 268-277] is employed. The model for binary systems is validated by comparing activity coefficient predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solutions model due to data insufficiencies are discussed. This model expands the variable temperature sodium-potassium model of Greenberg and Moller [Greenberg J., and Moller N. (1989) The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Cl-SO 4-H 2O system to high concentration from 0 to 250 °C. Geochim. Cosmochim. Acta53, 2503-2518] by evaluating Br - pure electrolyte and mixing solution parameters and the chemical potentials of three bromide solid phases: NaBr-2H 2O (cr), NaBr (cr) and KBr (cr).

Response of duplex Cr(N)/S and Cr(C)/S coatings on 316L stainless steel to tribocorrosion in 0.89% NaCl solution under plastic contact conditions.

PubMed

Sun, Y; Dearnley, P A; Mallia, Bertram

2017-08-01

Two duplex coatings, Cr(N)/S and Cr(C)/S, were deposited on 316 L stainless steel by magnetron sputtering. The effectiveness of these duplex coatings in improving the tribocorrosion behavior of medical alloys under elastic contact conditions has been demonstrated in a recent publication. The present work focused on the response of these duplex coatings to tribocorrosion under plastic contact conditions. Tribocorrosion tests were conducted in 0.89% NaCl solution at 37°C at an initial contact pressure of 740 MPa and under unidirectional sliding conditions for sliding duration up to 24 h. The results showed that during sliding in the corrosive solution, the duplex coatings were plastically deformed into the substrate to a depth about 1 μm. The Cr(C)/S duplex coating had sufficient ductility to accommodate the deformation without cracking, such that it was worn through gradually, leading to the gradual increase in open circuit potential (OCP) and coefficient of friction (COF). On the other hand, the Cr(N)/S duplex coating suffered from cracking at all tested potentials, leading to coating blistering after prolonged sliding at OCP and stable pit formation in the substrate beneath the coating at applied anodic potentials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1503-1513, 2017. © 2016 Wiley Periodicals, Inc.

Sensitive and selective detection of trivalent chromium using Hyper Rayleigh Scattering with 5,5'-dithio-bis-(2-nitrobenzoic acid)-modified gold nanoparticles.

PubMed

Hughes, Shantelle I; Dasary, Samuel S R; Singh, Anant K; Glenn, Zachery; Jamison, Hakim; Ray, Paresh C; Yu, Hongtao

2013-03-01

Hyper Rayleigh Scattering (HRS) and absorption spectral assays using surface-modified gold nanoparticles (AuNP) have been developed for sensitive and selective detection of trivalent chromium (Cr 3+ ) from other metal ions including hexavalent chromium (as Cr 2 O 7 2- ). Gold nanoparticles of 13 nm, covalently attached with 5,5'-dithio- bis -(2-nitrobenzoic acid) (AuNP-DTNBA), is used as a probe for both the absorption and HRS assays. AuNP-DTNBA is able to detect Cr 3+ at 20 ppb level at pH 6.0 using absorption spectral change of the AuNP-DTNBA. Visible color change can be observed when mixed with 250 ppb of Cr 3+ , while there is no color change when mixed with 2 ppm level of some of the most common metal ions such as Cr 2 O 7 2- , Hg 2+ , Ba 2+ , Fe 3+ , Pb 2+ , Na + , Zn 2+ , Cd 2+ , Co 2+ , Mn 2+ , Ca 2+ , and Ni 2+ . However, a color change is observed when mixed with Ni 2+ , Zn 2+ , and Cd 2+ at a concentration higher than 2 ppm. The detection limit for the HRS assay is on a remarkable 25 ppt level, and there is no detectable HRS signal at 2 ppm level for Cr 2 O 7 2- , Hg 2+ , Ba 2+ , Fe 3+ , Pb 2+ , Na + , Zn 2+ , Cd 2+ , Co 2+ , Mn 2+ , Ca 2+ , and Ni 2+ .

Experimental Determination of Solubilities of Sodium Polyborates In MgCl 2 Solutions: Solubility Constant of Di-Sodium Hexaborate Tetrahydrate, and Implications For the Diagenetic Formation of Ameghinite

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie; KNOX, Jandi; ...

2017-11-01

In this paper, solubility measurements were conducted for sodium polyborates in MgCl 2 solutions at 22.5 ± 0.5 °C. According to solution chemistry and XRD patterns, di-sodium tetraborate decahydrate (borax) dissolves congruently, and is the sole solubility-controlling phase, in a 0.01 mol/kg MgCl 2 solution: Na 2B 4O 7•10H 2O(cr) ⇌ 2Na + + 4B(OH) 4 + 2H + + H 2O(l). However, in a 0.1 mol/kg MgCl 2 solution borax dissolves incongruently and is in equilibrium with di-sodium hexaborate tetrahydrate: 2Na 2B 6O 10•4H 2O(cr) + 2Na + + 23H 2O(l) ⇌ 3Na 2B 4O 7•10H 2O(cr) + 2Hmore » +. In this study, the equilibrium constant (log K 0) for Reaction 2 at 25 °C and infinite dilution was determined to be –16.44 ± 0.13 (2σ) based on the experimental data and the Pitzer model for calculations of activity coefficients of aqueous species. In accordance with the log K 0 for Reaction 1 from a previous publication from this research group, and log K 0 for Reaction 2 from this study, the equilibrium constant for dissolution of di-sodium hexaborate tetrahydrate at 25 °C and at infinite dilution, Na 2B 6O 10•4H 2O(cr) + 10H 2O(l) ⇌ 2Na + + 6B(OH) 4 - + 4H + was derived to be –45.42 ± 0.16 (2σ). The equilibrium constants determined in this study can find applications in many fields. For example, in the field of nuclear waste management, the formation of di-sodium hexaborate tetrahydrate in brines containing magnesium will decrease borate concentrations, making less borate available for interactions with Am(III). In the field of experimental investigations, based on the equilibrium constant for Reaction 2, the experimental systems can be controlled in terms of acidity around neutral pH by using the equilibrium assemblage of borax and di-sodium hexaborate tetrahydrate at 25 °C. As salt lakes and natural brines contain both borate and magnesium as well as sodium, the formation of sodium hexaborate tetrahydrate may influence the chemical evolution of salt lakes and natural brines. Di-sodium hexaborate tetrahydrate is a polymorph of the mineral ameghinite [chemical formula Na 2B 6O 10•4H 2O; structural formula NaB 3O 3(OH) 4 or Na 2B 6O 6(OH) 8]. Finally, di-sodium hexaborate tetrahydrate could be a precursor of ameghinite and could be transformed when borate deposits are subject to diagenesis.« less

Experimental Determination of Solubilities of Sodium Polyborates In MgCl 2 Solutions: Solubility Constant of Di-Sodium Hexaborate Tetrahydrate, and Implications For the Diagenetic Formation of Ameghinite

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

Xiong, Yongliang; Kirkes, Leslie; KNOX, Jandi

In this paper, solubility measurements were conducted for sodium polyborates in MgCl 2 solutions at 22.5 ± 0.5 °C. According to solution chemistry and XRD patterns, di-sodium tetraborate decahydrate (borax) dissolves congruently, and is the sole solubility-controlling phase, in a 0.01 mol/kg MgCl 2 solution: Na 2B 4O 7•10H 2O(cr) ⇌ 2Na + + 4B(OH) 4 + 2H + + H 2O(l). However, in a 0.1 mol/kg MgCl 2 solution borax dissolves incongruently and is in equilibrium with di-sodium hexaborate tetrahydrate: 2Na 2B 6O 10•4H 2O(cr) + 2Na + + 23H 2O(l) ⇌ 3Na 2B 4O 7•10H 2O(cr) + 2Hmore » +. In this study, the equilibrium constant (log K 0) for Reaction 2 at 25 °C and infinite dilution was determined to be –16.44 ± 0.13 (2σ) based on the experimental data and the Pitzer model for calculations of activity coefficients of aqueous species. In accordance with the log K 0 for Reaction 1 from a previous publication from this research group, and log K 0 for Reaction 2 from this study, the equilibrium constant for dissolution of di-sodium hexaborate tetrahydrate at 25 °C and at infinite dilution, Na 2B 6O 10•4H 2O(cr) + 10H 2O(l) ⇌ 2Na + + 6B(OH) 4 - + 4H + was derived to be –45.42 ± 0.16 (2σ). The equilibrium constants determined in this study can find applications in many fields. For example, in the field of nuclear waste management, the formation of di-sodium hexaborate tetrahydrate in brines containing magnesium will decrease borate concentrations, making less borate available for interactions with Am(III). In the field of experimental investigations, based on the equilibrium constant for Reaction 2, the experimental systems can be controlled in terms of acidity around neutral pH by using the equilibrium assemblage of borax and di-sodium hexaborate tetrahydrate at 25 °C. As salt lakes and natural brines contain both borate and magnesium as well as sodium, the formation of sodium hexaborate tetrahydrate may influence the chemical evolution of salt lakes and natural brines. Di-sodium hexaborate tetrahydrate is a polymorph of the mineral ameghinite [chemical formula Na 2B 6O 10•4H 2O; structural formula NaB 3O 3(OH) 4 or Na 2B 6O 6(OH) 8]. Finally, di-sodium hexaborate tetrahydrate could be a precursor of ameghinite and could be transformed when borate deposits are subject to diagenesis.« less

AFLOWLIB.ORG: a Distributed Materials Properties Repository from High-throughput Ab initio Calculations

DTIC Science & Technology

2011-11-15

uncle) fcc (uncle) hcp (uncle) phase-diagram Ag Al Al Au Au Bi Bi Ca Ca Cd Cd Ce Ce Co Co Cr Cr Cu Cu Fe Fe Ga Ga Gd Gd Ge Ge Hf...Hf Hg Hg In In Ir Ir La La Li Li Mg Mg Mn Mn Mo Mo Na Na Nb Nb Ni Ni Os Os Pb Pb Pd Pd Pt Pt Rb Rb Re Re Rh Rh Ru Ru Sb Sb Sc...2 S. Curtarolo, A. N. Kolmogorov, and F. H. Cocks, High-throughput ab initio analysis of the Bi-In, Bi- Mg , Bi-Sb, In- Mg , In-Sb, and Mg -Sb systems

Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses.

PubMed

Ardini, Francisco; Soggia, Francesco; Abelmoschi, Maria Luisa; Magi, Emanuele; Grotti, Marco

2013-01-01

To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP-AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP-MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots.

Site of Action of Antidiuretic Hormone on Mammalian Nephrons.

DTIC Science & Technology

1981-01-01

techniques. Na and K concen- trations were determined by flamirne photometry and Cl by coulombmetric titration. 3ILO 14C- inulin and "Na were...of Cr in sequential Slop-flow samples. The appearance of 14C- inulin deriv ed from the posl-stop-Ilow IV infusion signalled the appearance of fresh

Na-rich character of metasomatic/metamorphic fluids inferred from preiswerkite in chromitite pods of the Khoy ophiolite in Iran: Role of chromitites as capsules of trapped fluids

NASA Astrophysics Data System (ADS)

Zaeimnia, Fatemeh; Arai, Shoji; Mirmohammadi, Mirsaleh

2017-01-01

We report a new occurrence of preiswerkite, a rare Na- and Al-rich trioctahedral mica (Na-analog of eastonite), from a high-Al (Cr# of chromite 0.4) chromitite pod of the Khoy meta-ophiolite in northwestern Iran. The preiswerkite is euhedral and associated with Ca-Cr-Al-garnet, clinochlore, titanite, and calcite. Preiswerkite and associated minerals fill cavities in the chromitite pod and are absent in the surrounding peridotites. The preiswerkite-rich aggregate is possibly representative of aqueous fluid supplied to the mantle section of the Khoy ophiolite. Peraluminous conditions, which are indispensable for preiswerkite formation, were established only in the pool of fluid trapped by the high-Al chromitite. The fluid and preiswerkite precipitates were isolated from the peridotite by the chromitite capsule. The Na-rich fluid was a precursor of the serpentinization fluid. The fluid is an analog of the fluid released from the subducting slab, which can precipitate jadeite under high-pressure conditions.

Reactions of sulphur mustard on impregnated carbons.

PubMed

Prasad, G K; Singh, Beer

2004-12-31

Activated carbon of surface area 1100 m2/gm is impregnated with 4% sodium hydroxide plus 3% Cr(VI) as CrO3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 degrees C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO3/C system, whereas on NaOH/CrO3/EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO3)2/C system it gave hemisulphur mustard and thiodiglycol. On RuCl3/C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard.

Utilization of steel, pulp and paper industry solid residues in forest soil amendment: relevant physicochemical properties and heavy metal availability.

PubMed

Mäkelä, Mikko; Watkins, Gary; Pöykiö, Risto; Nurmesniemi, Hannu; Dahl, Olli

2012-03-15

Industrial residue application to soil was investigated by integrating granulated blast furnace or converter steel slag with residues from the pulp and paper industry in various formulations. Specimen analysis included relevant physicochemical properties, total element concentrations (HCl+HNO3 digestion, USEPA 3051) and chemical speciation of chosen heavy metals (CH3COOH, NH2OH·HCl and H2O2+H2O2+CH3COONH4, the BCR method). Produced matrices showed liming effects comparable to commercial ground limestone and included significant quantities of soluble vital nutrients. The use of converter steel slag, however, led to significant increases in the total concentrations of Cr and V. Subsequently, total Cr was attested to occur as Cr(III) by Na2CO3+NaOH digestion followed by IC UV/VIS-PCR (USEPA 3060A). Additionally, 80.6% of the total concentration of Cr (370 mg kg(-1), d.w.) occurred in the residual fraction. However, 46.0% of the total concentration of V (2470 mg kg(-1), d.w.) occurred in the easily reduced fraction indicating potential bioavailability. Copyright © 2011 Elsevier B.V. All rights reserved.

Manganese-Chromium-Cyanide Clusters: Molecular MnCr 6(CN) 18 and Mn 3Cr 6(CN) 18 Species and a Related MnCr 3(CN) 9 Chain Compound

NASA Astrophysics Data System (ADS)

Heinrich, Julie L.; Sokol, Jennifer J.; Hee, Allan G.; Long, Jeffrey R.

2001-07-01

As part of an ongoing effort to design new single-molecule magnets, we are exploring synthetic routes to high-nuclearity metal-cyanide clusters. Here, we report the results of solution assembly reactions between [(Me3tacn)Cr(CN)3] (Me3tacn= N,N‧,N″-trimethyl-1,4,7-triazacyclononane) and selected manganese(II) salts. Reaction with the perchlorate salt in the presence of AClO4 (A=Na, K) gives A[(Me3tacn)6MnCr6(CN)18] (ClO4)3, featuring a heptanuclear cluster in which six [(Me3tacn)Cr(CN)3] units surround a central MnII ion. The Mn coordination geometry closely approaches a trigonal prism, with triangular faces twisted away from a fully eclipsed position by an angle of 12.8° and 11.3° for A=Na and K, respectively. The magnetic behavior of both compounds indicates weak antiferromagnetic coupling between neighboring MnII and CrIII centers (J=-3.0 and -3.1 cm-1, respectively) to give an S={13}/{2}; ground state. Alternatively, addition of sodium tetraphenylborate to the reaction solution yields [(Me3tacn)6(H2O)6Mn3Cr6(CN)18] (BPh4)6·12H2O, in which attachment of two MnII ions to the preceding cluster generates a new species with two trigonal bipyramids sharing a common vertex. This compound displays magnetic behavior consistent with weak antiferromagnetic coupling and an S={3}/{2} ground state. Finally, a reaction employing manganese(II) triflate is found to produce the one-dimensional solid [(Me3tacn)3MnCr3(CN)9](CF3SO3)2, exhibiting a closely related chain structure, and, again, weak antiferromagnetic coupling.

Electrochemical corrosion behaviour of dental/implant alloys in saline medium.

PubMed

Sharma, Mohit; Kumar, A V Ramesh; Singh, Nirbhay

2008-07-01

Dental alloys implanted in mouth are exposed to various aggressive conditions. Keeping this in view, corrosion behaviour of various dental alloys viz. Ni-Cr, Co-Cr, Cu-Ni-Al and commercially pure Ti (c.p. Ti) were studied in 3% NaCl medium by using Tafel polarization, cyclic polarization and electrochemical impedance spectroscopy techniques. EIS studies were carried out for different duration viz. 1 h, 1 day and 7 days to evaluate the stability of passive film and change in corrosion characteristics with time. It has been found that for Ni-Cr, Co-Cr (DRDO developed) and c.p. Ti the passive film characteristic changed with time whereas for Co-Cr (commercial) and Cu-Ni-Al alloys, the passive film characteristics remained same. From DC electrochemical studies various parameters viz. i(corr), E(corr), i(pass), E(pass) were evaluated. The corrosion rates were observed to be in the order Cu-Ni-Al > Co-Cr (commercial) > Ni-Cr > c.p. Ti > Co-Cr (DRDO).

[Study on corrosion resistance of three non-noble porcelain alloys].

PubMed

Wu, Zhikai; Xu, Sheng; Li, Wei; Teng, Jin; Li, Ning

2011-10-01

To study the electrochemical corrosion behavior of Co-Cr, Ni-Cr and Ni-Cr-Be based porcelain alloys in NaCl solution. Five samples of each alloy were made respectively, electric polarization curve of each alloy was obtained using potentiodynamic polarization technique. Self-corrosion potential (E(corr)), self-corrosion current density (I(corr), passive region and transpassivation potential were tested. Microstructure and constituent was examined using scanning electron microscopy and energy dispersive spectroscopy. Co-Cr alloy possessed the most desirable corrosion resistance because of its integrated, homogeneous and compact passive film. The poor compactness of Ni-Cr alloy's passive film decreased its corrosion resistance. Ni-Cr-Be alloy exhibited the worst corrosion resistance due to the Cr and Mo depleted Ni-Be eutectic phases in the alloy. Taking biological security into consideration, it is necessary to avoid the application of porcelain alloys with Be element. Co-Cr alloy with better biocompatibility possesses much broader prospect in the field of dental restoration.

Synthesis and characterization of metal nanoparticles templated chitosan-SiO2 catalyst for the reduction of nitrophenols and dyes.

PubMed

Ali, Fayaz; Khan, Sher Bahadar; Kamal, Tahseen; Alamry, Khalid A; Bakhsh, Esraa M; Asiri, Abdullah M; Sobahi, Tariq R A

2018-07-15

Different metal nanoparticles (MNPs) templated on chitosan-silica (CH-SiO 2 ) nanocomposite fiber were prepared via simple and fast method of the metal ions uptake by fiber and their subseqent reduction using strong reducing agent. The performance difference of CH-SiO 2 templated with Cu, Co, Ag and Ni nanoparticles for both reduction of 4-nitroaniline (4-NA) and decolorization of congo red (CR) was investigated. The Cu nanoparticles loaded CH-SiO 2 (Cu/CH-SiO 2 ), showed high catalytic efficiencies in the reduction of 4-NA and CR, as compared to other loaded MNP fibers. The apparent rate constants of 6.17 × 10 -3  s -1 and 1.68 × 10 -2  s -1 and turnover frequencies (TOF) of 4.693 h -1 and 3.965 h -1 were observed for the reduction of 4-NA and CR, respectively. In addition, the catalytic activity of Cu/CH-SiO 2 catalyst was also examined and found efficient in the reduction of nitrophenols (2-NP, 3-NP and 4-NP), and other dyes. Thus, Cu/CH-SiO 2 with excellent catalytic activity can also be employed for other applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Guidance Document: Surface Soils Sampling for Munitions Residues in Military Live Fire Training Ranges: Canadian Protocol

DTIC Science & Technology

2012-12-01

NA Boron B 0.5 NA Cadmium Cd 0.3 22 Calcium Ca 4.0 NA Chromium Cr 0.5 87 Cobalt Co 0.5 300 Copper Cu 0.4 91 Iron Fe 0.6 NA Lead Pb 2.5 600...on their susceptibility to initiation. Primary explosives, which include lead azide, lead styphnate, and mercury fulminate, are highly susceptible...ballistic properties. The degradation of NC leads to substances which speed up the degradation process, or else an autocatalytic reaction. To counteract

Characterization of new polymer-grafted protein cation exchangers developed by partial neutralization of carboxyl groups derivatized by modification of poly(ethylenimine)-Sepharose with succinic anhydride.

PubMed

Zhao, Yangyang; Dong, Xiaoyan; Yu, Linling; Liu, Yang; Sun, Yan

2018-05-18

Previously, we have studied protein adsorption and chromatographic behaviors on poly(ethylenimine) (PEI)-grafted Sepharose FF anion-exchange resins, and found that protein uptake rates increased greatly when PEI grafting density reached over a critical ionic capacity (cIC) due to the occurrence of the "chain delivery" effect. Moreover, by partial charge neutralization of starting resin FF-PEI-L740 (IC = 740 mmol/L, larger than the cIC) with sodium acetate to FF-PEI-R440, it exhibited a three-fold increase in uptake rate over FF-PEI-L740. In this work, to take the advantages of PEI and extend the applications of the PEI-grafted resins in cation-exchange chromatography, a series of cation exchangers of five different ICs were developed. First, the charged of FF-PEI-L740 was reversed from positive to negative by reaction with excess succinic anhydride, which created a cation-exchanger with an IC of 970 mmol/L (FF-FEI-C970). FF-PEI-C970 was further modified with ethanolamine for partial charge neutralizations, leading to the preparation of four charge-reduced cation exchangers with IC values (in mmol/L) of 780, 630, 560 and 430, which were denoted as FF-PEI-CR780, -CR630 -CR560 and -CR430, respectively. Protein adsorption and chromatographic behaviors were investigated using lysozyme (Lys) as the model protein. It was found that, the resins of high and moderate IC values (IC ≥ 560 mmol/L) afforded adsorption capacities up to over 230 mg/mL. Besides, the uptake rate, represented by the effective pore diffusivity (D e/ D 0 ), exhibited significant increase from 0.067 (FF-PEI-C970 and FF-PEI-CR780) to 0.343 (FF-PEI-CR630 and FF-PEI-CR560) and then to 1.035 (FF-PEI-CR430) with decreasing IC. It was considered that decreasing IC led to the decreased protein binding sites (binding strength), which encouraged the occurrence of the "chain delivery" effect. Moreover, the resins of high and moderate IC values, particularly, the resins of moderate IC values (FF-PEI-CR630 and FF-PEI-CR560), presented both high adsorption capacities and uptake kinetics at 0-100 mmol/L NaCl. Besides, dynamic binding capacity achieved 150 mg/mL for the resins of moderate IC values at 0 mmol/L NaCl concentration, and afforded >110 mg/mL for the resin of high IC values at 0-100 mmol/L NaCl concentration. The results proved the excellent IEC performance of the PEI-derived cation exchangers. Copyright © 2018 Elsevier B.V. All rights reserved.

Lasing characteristics of refractive-index-matched composite Y3Al5O12 rods employing transparent ceramics for solar-pumped lasers

NASA Astrophysics Data System (ADS)

Hasegawa, Kazuo; Ichikawa, Tadashi; Takeda, Yasuhiko; Ikesue, Akio; Ito, Hiroshi; Motohiro, Tomoyoshi

2018-04-01

We have proposed a new configuration of solar-pumped lasers employing transparent ceramic rods. The laser rod has a composite structure consisting of a Nd/Cr:YAG gain domain surrounded by Gd:YAG with the same refractive index as that of Nd/Cr:YAG. The lasing mode is well controlled by the output coupler, and the parasitic oscillation is suppressed, owing to the refractive index matching. A high laser slope efficiency and a low laser oscillation threshold were achieved owing to the suppressed absorption outside the lasing mode, which was previously a serious issue for the end-pumping configuration using a high-NA focusing optics. The laser oscillation threshold of 136 mW and the slope efficiency of 25.3% were derived. Thus, we have resolved the issue of useless absorption associated with the high-NA end-pumping, and achieved significant improvements compared with the conventional structure of uniform Nd/Cr:YAG.

An investigation on the biotribocorrosion behaviour of CoCrMo alloy grafted with polyelectrolyte brush.

PubMed

Zhang, Hong-Yu; Zhu, Yu-Jiao; Hu, Xiang-Yu; Sun, Yan-Fang; Sun, Yu-Long; Han, Jian-Min; Yan, Yu; Zhou, Ming

2014-01-01

Surface grafting of polyelectrolyte brush, such as 3-sulfopropyl methacrylate potassium salt (SPMK), on hip implant materials has been reported to reduce the wear of the orthopaedic bearing surface. However, the biotribocorrosion behaviour of the SPMK brush has not been taken into consideration in previous research. In the present study, SPMK was grafted on Co28Cr6Mo alloy through photo-induced polymerization, and the biotribocorrosion behaviour was investigated by a series of frictional-electrochemical tests using a universal materials tester combined with an electrochemical measurement (three-electrode) system. Co28Cr6Mo disk and polyethylene (PE) pin were used as the contact pair, and the lubricants were 0.9% saline solution (NaCl) and 0.9% saline solution coupled with 25% bovine serum albumin (BSA). The results showed that SPMK was successfully grafted on Co28Cr6Mo alloy, which was confirmed by the comparison of Raman spectroscopy and static contact angle of the samples before and after surface modification. The greatly reduced electrochemical parameters such as corrosion current and pitting potential indicated that the corrosion rate of Co28Cr6Mo alloy was significantly reduced following SPMK grafting. Additionally, the frictional-electrochemical coupled measurement performed under reciprocating sliding demonstrated that the lowest corrosion current was obtained for the SPMK-grafted Co28Cr6Mo disk, with 0.9% NaCl coupled with 25% BSA as the electrolyte. It is indicated from the present study that SPMK polyelectrolyte brush can greatly improve the anti-biotribocorrosion properties of Co28Cr6Mo alloy, and thus has potential application on surface modification of hip implant materials.

Inhibition of plasma membrane Ca(2+)-ATPase by CrATP. LaATP but not CrATP stabilizes the Ca(2+)-occluded state.

PubMed

Moreira, Otacilio C; Rios, Priscila F; Barrabin, Hector

2005-07-15

The bidentate complex of ATP with Cr(3+), CrATP, is a nucleotide analog that is known to inhibit the sarcoplasmic reticulum Ca(2+)-ATPase and the Na(+),K(+)-ATPase, so that these enzymes accumulate in a conformation with the transported ion (Ca(2+) and Na(+), respectively) occluded from the medium. Here, it is shown that CrATP is also an effective and irreversible inhibitor of the plasma membrane Ca(2+)-ATPase. The complex inhibited with similar efficiency the Ca(2+)-dependent ATPase and the phosphatase activities as well as the enzyme phosphorylation by ATP. The inhibition proceeded slowly (T(1/2)=30 min at 37 degrees C) with a K(i)=28+/-9 microM. The inclusion of ATP, ADP or AMPPNP in the inhibition medium effectively protected the enzyme against the inhibition, whereas ITP, which is not a PMCA substrate, did not. The rate of inhibition was strongly dependent on the presence of Mg(2+) but unaltered when Ca(2+) was replaced by EGTA. In spite of the similarities with the inhibition of other P-ATPases, no apparent Ca(2+) occlusion was detected concurrent with the inhibition by CrATP. In contrast, inhibition by the complex of La(3+) with ATP, LaATP, induced the accumulation of phosphoenzyme with a simultaneous occlusion of Ca(2+) at a ratio close to 1.5 mol/mol of phosphoenzyme. The results suggest that the transport of Ca(2+) promoted by the plasma membrane Ca(2+)-ATPase goes through an enzymatic phospho-intermediate that maintains Ca(2+) ions occluded from the media. This intermediate is stabilized by LaATP but not by CrATP.

Syntheses and characterization of elpasolite-type ammonium alkali metal hexafluorometallates(III)

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

Mi Jinxiao; Key Laboratory of New Processing Technology for Nonferrous Metals and Materials; Luo Shuming

Crystal structures of three fluorides (NH{sub 4}){sub 2}NaFeF{sub 6}, (Fe), (NH{sub 4}){sub 2}NaGaF{sub 6}, (Ga), and (NH{sub 4}){sub 2}NaCrF{sub 6}, (Cr), as well as a substituted compound [(NH{sub 4}){sub 1-x}K{sub x}]{sub 2}KAlF{sub 6} (x{approx}0.17), (Al), have been refined using single-crystal and powder X-ray diffraction techniques. All these four ammonium hexafluorides have a cubic elpasolite-type structure and crystallize in the space group Fm3-bar m with lattice constants a=8.483(3), 8.450 (3), 8.4472(2) and 8.724(3) A for compounds (Fe), (Ga), (Cr) and (Al), respectively. The effective ionic radius of the ammonium ion calculated from those compounds has a mean value of R=1.729 Amore » for CN=12. An ultraviolet-visible absorption spectrum of (NH{sub 4}){sub 2}NaCrF{sub 6}, measured at room temperature, gives a crystal field (Dq=1575 cm{sup -1}) and Racah parameters (B=758 cm{sup -1} and C=3374 cm{sup -1}). Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound (Al), and interpreted to arise from four strong hydrogen bonds (F...H-N) that are distributed in a square form around each fluorine atom. - Graphical abstract: Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound [(NH{sub 4}){sub 1-x}K{sub x}]{sub 2}KAlF{sub 6} (x{approx}0.17), and interpreted to arise from four strong hydrogen bonds (F...H-N) that are distributed in a square form around each fluorine atom. The endmembers' phase transitions at low temperature are believed to be caused by them.« less

Ion-exchange synthesis and superconductivity at 8.6 K of Na2Cr3As3 with quasi-one-dimensional crystal structure

NASA Astrophysics Data System (ADS)

Mu, Qing-Ge; Ruan, Bin-Bin; Pan, Bo-Jin; Liu, Tong; Yu, Jia; Zhao, Kang; Chen, Gen-Fu; Ren, Zhi-An

2018-03-01

A Cr-based quasi-one-dimensional superconductor N a2 Cr3As3 was synthesized by an ion-exchange method in a sodium naphthalenide solution. The crystals are threadlike and the structure was analyzed by x-ray diffraction with a noncentrosymmetric hexagonal space group P -6 m 2 (No. 187), in which the (Cr3As3 )2 - linear chains are separated by N a+ ions, and the refined lattice parameters are a =9.239 (2 )Å and c =4.209 (6 )Å . The measurements for electrical resistivity, magnetic susceptibility, and heat capacity reveal a superconducting transition with unconventional characteristic at 8.6 K, which exceeds that of all previously reported Cr-based superconductors.

Specifiers Properties Information Exchange (SPie): Minimum Building Information Model (BIM) Object Definitions

DTIC Science & Technology

2013-03-01

Weave Welding Method Wheel Assembly Wind Load Wind Loads Wind Uplift Resistance Wind Uplift Resistance Class Window Category Window Finish Window... wind - blast Elongation UFGS 2.1 percent Insert Value Visual Defects UFGS 2.1 n/a Insert Value ERDC/CERL CR-13-1 39 Attribute Source...Sustainability COBie Guide n/a insert reqts FRP Strengthening UFGS 1.2 n/a seismic - wind - blast Elongation UFGS 2.2 percent Insert Value Tensile

Application of plasma electrolysis method for simultaneous phenol and Cr(VI) wastewater degradation using Na2SO4 electrolyte

NASA Astrophysics Data System (ADS)

Harianti, Aulia Rahmi; Saksono, Nelson

2017-11-01

Phenol and Cr (VI) are two types of wastewater known as dangerous and difficult to degrade. Through this study, phenol and Cr (VI) metal wastewater were degraded simultaneously using plasma electrolysis method by reactive species, •OH and H•. The variation of anode depth and position of plasma formation as independent variables correlated with yield of hydroxyl radical, percentage of phenol and Cr (VI) degradation, and specific energy. Within 30 minutes, phenol was degraded to 98.4% and Cr (VI) was degraded to 93.35% with 171.05 kJ/mmol in specific energy, and 174.53 ppm in COD. The optimum condition was obtained in anodic plasma and 1.5 cm in anode depth. The highest degradation percentage of phenol and Cr (VI) were 99.79% and 97.33% achieved during 180 minutes of plasma electrolysis process.

CrII Reactivity of Taurine/α-Ketoglutarate Dioxygenase

PubMed Central

Grzyska, Piotr K.; Hausinger, Robert P.

2008-01-01

The interaction of CrII with taurine/α-ketoglutarate (αKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with αKG to the FeII/αKG-binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen -sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This pre-formed side chain is generated by intracellular self-hydroxylation of Tyr-73 to form DOPA, which is subsequently oxidized to the quinone. No chromophore is generated when using NaBH4-treated sample, protein isolated from anaerobically grown cells, inactive TauD variants that are incapable of self-hydroxylation, or the Y73F active mutant of TauD. A CrIII-DOPA semiquinone also was observed in the herbicide hydroxylase SdpA. PMID:17973473

Cr(II) reactivity of taurine/alpha-ketoglutarate dioxygenase.

PubMed

Grzyska, Piotr K; Hausinger, Robert P

2007-11-26

The interaction of CrII with taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with alphaKG to the FeII/alphaKG binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen-sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This preformed side chain is generated by intracellular self-hydroxylation of Tyr-73 to form DOPA, which is subsequently oxidized to the quinone. No chromophore is generated when using NaBH4-treated sample, protein isolated from anaerobically grown cells, inactive TauD variants that are incapable of self-hydroxylation, or the Y73F active mutant of TauD. A CrIII-DOPA semiquinone also was observed in the herbicide hydroxylase SdpA.

First principles study of structural and magnetic properties of transition metal nitrides TMN (TM = Cr, Mn)

NASA Astrophysics Data System (ADS)

Rajeswarapalanichamy, R.; Amudhavalli, A.; Manikandan, M.; Kavitha, M.; Iyakutti, K.

2017-09-01

The structural stability of chromium nitride (CrN) and manganese nitride (MnN) is investigated among four different structures, namely, NaCl (Fm3m), zinc blende (F4-3m), orthorhombic (Pnma) and tetragonal (I4/mmm). It is found that the most stable phase is the zinc blende phase for CrN and MnN. The structural phase transition from zinc blende to orthorhombic phase is predicted at high pressure. At normal pressure, CrN and MnN are found to be antiferromagnetic. As the pressure is increased, antiferromagnetic-to-nonmagnetic phase transition is observed at the pressures of 169.5 GPa in CrN and 206 GPa in MnN. The elastic constants obey the Born-Huang criteria, suggesting that they are mechanically stable. The calculated B/G values indicate that CrN and MnN are ductile in nature.

Clean Metal Finishing Alternatives

DTIC Science & Technology

2006-05-01

Cr, must heat treat for hardness 4 4 Trivalent chrome Trivalent plating chemistry Varying success, some must be brush plate 3 3 Alloy plating...metals. Hard coating deposition unproven. 3 N/A Weld coating Electrospark Deposition/ Alloying (ESD/ ESA) Microarc welding Localized repair of non...Alternatives to chromate conversion coatings Al TriChrome Pretreatment (TCP)* – AnoChem TCP, Aluminescent, TCP-HF Trivalent Cr3+ conversion with Zr

IN SITU SOURCE TREATMENT OF CR(VI) USING A FE(II)-BASED REDUCTANT BLEND: LONG-TERM MONITORING AND EVALUATION

EPA Science Inventory

The long-term effectiveness of a FeSO4 + Na2S2O4 reductant solution blend for in situ saturated zone treatment of dissolved and solid phase Cr(VI) in a high pH chromite ore processing solid waste (COPSW) fill material was investigated. Two field pilot injection studies were cond...

Hypoxic Tumor Kinase Signaling Mediated by STAT5A in Development of Castration-Resistant Prostate Cancer

PubMed Central

Røe, Kathrine; Bratland, Åse; Vlatkovic, Ljiljana; Ragnum, Harald Bull; Saelen, Marie Grøn; Olsen, Dag Rune; Marignol, Laure; Ree, Anne Hansen

2013-01-01

In this study, we hypothesized that androgen-deprivation therapy (ADT) in prostate cancer, although initially efficient, induces changes in the tumor kinome, which subsequently promote development of castration-resistant (CR) disease. Recognizing the correlation between tumor hypoxia and poor prognosis in prostate cancer, we further hypothesized that such changes might be influenced by hypoxia. Microarrays with 144 kinase peptide substrates were applied to analyze CWR22 prostate carcinoma xenograft samples from ADT-naïve, androgen-deprived (AD), long-term AD (ADL), and CR disease stages. The impact of hypoxia was assessed by matching the xenograft kinase activity profiles with those acquired from hypoxic and normoxic prostate carcinoma cell cultures, whereas the clinical relevance was evaluated by analyzing prostatectomy tumor samples from patients with locally advanced disease, either in ADT-naïve or early CR disease stages. By using this novel peptide substrate microarray method we revealed high kinase activity mediated by signal transducer and activator of transcription 5A (STAT5A) in CR prostate cancer. Additionally, we uncovered high STAT5A kinase activity already in regressing ADL xenografts, before renewed CR growth was evidenced. Finally, since increased STAT5A kinase activity also was detected after exposing prostate carcinoma cells to hypoxia, we propose long-term ADT to induce tumor hypoxia and stimulate STAT5A kinase activity, subsequently leading to renewed CR tumor growth. Hence, the study detected STAT5A as a candidate to be further investigated for its potential as marker of advanced prostate cancer and as possible therapeutic target protein. PMID:23675504

Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.

PubMed

Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

2014-01-30

FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of the bactericidal effect of Nd:YAG, Er:YAG, Er,Cr:YSGG laser radiation, and antimicrobial photodynamic therapy (aPDT) in experimentally infected root canals.

PubMed

Cheng, Xiaogang; Guan, Sumin; Lu, Hong; Zhao, Chunmiao; Chen, Xingxing; Li, Na; Bai, Qian; Tian, Yu; Yu, Qing

2012-12-01

In recent years, various laser systems have been introduced into the field of laser-assisted endodontic therapy. The aim of this study was to evaluate the bactericidal effect of Nd:YAG, Er:YAG, Er,Cr:YSGG laser radiation, and antimicrobial photodynamic therapy (aPDT) in experimentally infected root canals compared with standard endodontic treatment of 5.25% sodium hypochlorite (NaClO) irrigation. Two hundred and twenty infected root canals from extracted human teeth (contaminated with Enterococcus faecalis ATCC 4083 for 4 weeks) were randomly divided into five experimental groups (Nd:YAG, Er:YAG + 5.25% NaClO + 0.9% normal saline + distilled water (Er:YAG/NaClO/NS/DW), Er:YAG + 0.9% normal saline + distilled water (Er:YAG/NS/DW), Er,Cr:YSGG, and aPDT) and two control groups (5.25% NaClO as positive control and 0.9% normal saline (NS) as negative control). The numbers of bacteria on the surface of root canal walls and at different depths inside dentinal tubules before and after treatment were analyzed by means of one-way analysis of variance (one-way ANOVA). The morphology of bacterial cells before and after treatment was examined by scanning electron microscopy (SEM). After treatment, the bacterial reductions in the experimental groups and the positive control group were significantly greater than that of the negative control group (P < 0.001). However, only Er:YAG/NaClO/NS/DW group showed no bacterial growth (the bacterial reduction reached up to 100%) on the surface of root canal walls or at 100/200 µm inside the dentinal tubules. All the laser radiation protocols tested, especially Er:YAG/NaClO/NS/DW, have effective bactericidal effect in experimentally infected root canals. Er:YAG/NaClO/NS/DW seems to be an ideal protocol for root canal disinfection during endodontic therapy. Copyright © 2012 Wiley Periodicals, Inc.

Conversion of cellulose and cellobiose into sorbitol catalyzed by ruthenium supported on a polyoxometalate/metal-organic framework hybrid.

PubMed

Chen, Jinzhu; Wang, Shengpei; Huang, Jing; Chen, Limin; Ma, Longlong; Huang, Xing

2013-08-01

Cellulose and cellobiose were selectively converted into sorbitol over water-tolerant phosphotungstic acid (PTA)/metal- organic-framework-hybrid-supported ruthenium catalysts, Ru-PTA/MIL-100(Cr), under aqueous hydrogenation conditions. The goal was to investigate the relationship between the acid/metal balance of bifunctional catalysts Ru-PTA/MIL-100(Cr) and their performance in the catalytic conversion of cellulose and cellobiose into sugar alcohols. The control of the amount and strength of acid sites in the supported PTA/MIL-100(Cr) was achieved through the effective control of encapsulated-PTA loading in MIL-100(Cr). This design and preparation method led to an appropriately balanced Ru-PTA/MIL-100(Cr) in terms of Ru dispersion and hydrogenation capacity on the one hand, and acid site density of PTA/MIL-100(Cr) (responsible for acid-catalyzed hydrolysis) on the other hand. The ratio of acid site density to the number of Ru surface atoms (nA /nRu ) of Ru-PTA/MIL-100(Cr) was used to monitor the balance between hydrogenation and hydrolysis functions; the optimum balance between the two catalytic functions, that is, 8.84

Tetragonal distortions of some tetragonal Cr 3+ centers in fluoroperovskite ABF 3 crystals

NASA Astrophysics Data System (ADS)

Zhou, Qing; Wu, Hong-Ye; Wu, Xiao-Xuan; Zheng, Wen-Chen

2006-07-01

The tetragonal distortions [characterized by the displacement Δ R of the F - ion intervening in Cr 3+ and V B (B 2+ vacancy) or M + ion in B 2+ site] for Cr 3+-V B and Cr 3+-Li + centers in Cr 3+-doped fluoroperovskites KBF 3 (B = Mg, Zn) and ACdF 3 (A = K, Rb, Cs) and also for Cr 3+-Na + center in KZnF 3 have been studied by calculating the EPR parameters D, g|| and g⊥ from the crystal-field theory. From the studies, an interesting trend is suggested, i.e., when the size of the co-doped monovalent impurity M + in the nearest neighbor B 2+ site is comparable to that of the replaced B 2+ ion, the displacement Δ R of the intervening F - ion in Cr 3+-M + center is smaller than that in Cr 3+-V B center and if the M + iron is much smaller or much larger than that of the replaced B 2+ ion, the displacement Δ R in Cr 3+-M + center is greater than that in Cr 3+-V B center. The causes of the trend are discussed.

Tetragonal distortions of some tetragonal Cr3+ centers in fluoroperovskite ABF3 crystals.

PubMed

Zhou, Qing; Wu, Hong-Ye; Wu, Xiao-Xuan; Zheng, Wen-Chen

2006-07-01

The tetragonal distortions [characterized by the displacement DeltaR of the F(-) ion intervening in Cr(3+) and V(B) (B(2+) vacancy) or M(+) ion in B(2+) site] for Cr(3+)-V(B) and Cr(3+)-Li(+) centers in Cr(3+)-doped fluoroperovskites KBF(3) (B=Mg, Zn) and ACdF(3) (A=K, Rb, Cs) and also for Cr(3+)-Na(+) center in KZnF(3) have been studied by calculating the EPR parameters D, g(parallel) and g(perpendicular) from the crystal-field theory. From the studies, an interesting trend is suggested, i.e., when the size of the co-doped monovalent impurity M(+) in the nearest neighbor B(2+) site is comparable to that of the replaced B(2+) ion, the displacement DeltaR of the intervening F(-) ion in Cr(3+)-M(+) center is smaller than that in Cr(3+)-V(B) center and if the M(+) iron is much smaller or much larger than that of the replaced B(2+) ion, the displacement DeltaR in Cr(3+)-M(+) center is greater than that in Cr(3+)-V(B) center. The causes of the trend are discussed.

Environmental degradation of oxidation resistant and thermal barrier coatings for fuel-flexible gas turbine applications

NASA Astrophysics Data System (ADS)

Mohan, Prabhakar

The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air ingestion. The presence of vanadium, sulfur, phosphorus, sodium and calcium impurities in alternative fuels warrants a clear understanding of high-temperature materials degradation for the development of fuel-flexible gas turbine engines. Degradation due to CMAS is a critical problem for gas turbine components operating in a dust-laden environment. In this study, high-temperature degradation due to aggressive deposits such as V2O5, P2O 5, Na2SO4, NaVO3, CaSO4 and a laboratory-synthesized CMAS sand for free-standing air plasma sprayed (APS) yttria stabilized zirconia (YSZ), the topcoat of the TBC system, and APS CoNiCrAlY, the bond coat of the TBC system or a stand-alone ORC, is examined. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study demonstrated that the V2O5 melt degrades the APS YSZ through the formation of ZrV2O7 and YVO 4 at temperatures below 747°C and above 747°C, respectively. Formation of YVO4 leads to the depletion of the Y2O 3 stabilizer and the deleterious transformation of the YSZ to the monoclinic ZrO2 phase. The investigation on the YSZ degradation by Na 2SO4 and a Na2SO4 + V2O 5 mixture (50-50 mol. %) demonstrated that Na2SO4 itself did not degrade the YSZ, however, in the presence of V2O 5, Na2SO4 formed vanadates such as NaVO3 that degraded the YSZ through YVO4 formation at temperature as low as 700°C. The APS YSZ was found to react with the P2O 5 melt by forming ZrP2O7 at all temperatures. This interaction led to the depletion of ZrO2 in the YSZ (i.e., enrichment of Y2O3 in t'-YSZ) and promoted the formation of the fluorite-cubic ZrO2 phase. Above 1250°C, CMAS deposits were observed to readily infiltrate and significantly dissolve the YSZ coating via thermochemical interactions. Upon cooling, zirconia reprecipitated with a spherical morphology and a composition that depended on the local melt chemistry. The molten CMAS attack destabilized the YSZ through the detrimental phase transformation (t' → t → f + m). Free standing APS CoNiCrAlY was also prone to degradation by corrosive molten deposits. The V2O5 melt degraded the APS CoNiCrAlY through various reactions involving acidic dissolution of the protective oxide scale, which yielded substitutional-solid solution vanadates such as (Co,Ni) 3(VO4)2 and (Cr,Al)VO4. The molten P2O5, on the other hand, was found to consume the bond coat constituents significantly via reactions that formed both Ni/Co rich phosphates and Cr/Al rich phosphates. Sulfate deposits such as Na2SO 4, when tested in encapsulation, damaged the CoNiCrAlY by Type I acidic fluxing hot corrosion mechanisms at 1000°C that resulted in accelerated oxidation and sulfidation. The formation of a protective continuous Al 2O3 oxide scale by preoxidation treatment significantly delayed the hot corrosion of CoNiCrAlY by sulfates. However, CoNiCrAlY in both as-sprayed and preoxidized condition suffered a significant damage by CaSO4 deposits via a basic fluxing mechanism that yielded CaCrO4 and CaAl2O4. The CMAS melt also dissolved the protective Al2O3 oxide scale developed on CoNiCrAlY by forming anorthite platelets and spinel oxides. Based on the detailed investigation on degradation of the APS YSZ and CoNiCrAlY by various corrosive deposits, an experimental attempt was carried out to mitigate the melt-induced deposit attack. Experimental results from this study demonstrate, for the first time, that an oxide overlay produced by electrophoretic deposition (EPD) can effectively perform as an environmental barrier overlay for APS TBCs. The EPD protective overlay has a uniform and easily-controllable thickness, uniformly distributed closed pores and tailored chemistry. The EPD Al2O3 and MgO overlays were successful in protecting the APS YSZ TBCs against CMAS attack and hot corrosion attack (e.g., sulfate and vanadate), respectively. Furnace thermal cyclic oxidation testing of overlay-modified TBCs on bond-coated superalloy also demonstrated the good adhesive durability of the EPD Al2O3 overlay.

JCL (Job Control Language) Procedures to Run the Hull Code on the Cyber 205 Computer Installed on CSIRONET.

DTIC Science & Technology

1986-11-01

START THE RUN>>> USERNUIDNUPW. CHARGEGROUPNPID. SETJOB, DC= NO . COMMENT . GET CR ATTACH THE INPUT DATA TO GO TO VSOS. GET, INDATA=DATFILE/NA. IFE...NtPW. CHARGEGROUPNPID. SETTL, 200. SETJOB. DC= NO . COMMENT . RUN SAIL ON NOS TO GENERATE THE MAIN PROGRAM. PURGE, SAl LOUT/NA. PURGE, PROG-PROBLEMID...NOSPASS. CHARGEDFCDFCPR.F. SETJOB. DC= NO . COMMENT . GET OR ATTACH THE INPUT DATA To Go To VSOS. GET. INDATA=MYDATA/NA. IFE. .NOT.FILE(INDATA.AS) .DOATT

Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol

NASA Astrophysics Data System (ADS)

Aktas, S.; Eyuboglu, C.; Morcali, M. H.; Özbey, S.; Sucuoglu, Y.

2015-05-01

In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K2Cr2O7 than Na2Cr2O7. On the other hand, in the strongly acidic regime, ethanol acted as a reducing agent role in that chromium(VI) was converted into Cr(III) whereas ethanol itself was oxidized to carbon dioxide and water. Subsequently, chromium hydroxide was obtained by the help of sodium hydroxide and converted to chromium oxide by heating at 800 °C, as indicated in thermo gravimetric analysis (TGA).

Influence of graphite-alloy interactions on corrosion of Ni-Mo-Cr alloy in molten fluorides

NASA Astrophysics Data System (ADS)

Ai, Hua; Hou, Juan; Ye, Xiang-Xi; Zeng, Chao Liu; Sun, Hua; Li, Xiaoyun; Yu, Guojun; Zhou, Xingtai; Wang, Jian-Qiang

2018-05-01

In this study, the effects of graphite-alloy interaction on corrosion of Ni-Mo-Cr alloy in molten FLiNaK salt were investigated. The corrosion tests of Ni-Mo-Cr alloys were conducted in graphite crucibles, to examine the differences of test specimens in conditions of electric contact and isolated with graphite, respectively. The corrosion attack is severer with more weight loss and deeper Cr depletion layer in samples electric contact with graphite than those isolated with graphite. The occurrence of galvanic corrosion between alloy specimens and graphite container was confirmed by electrochemical measurement. The corrosion is controlled by nonelectric transfer in isolated test while electrochemical reaction accelerated corrosion in electric contact test.

Effects of intrinsic and extrinsic point defects on epitaxial single crystal copper-indium(1-x)-gallium(x)-diselenide

NASA Astrophysics Data System (ADS)

Schroeder, David James

From the results presented here a number of conclusions regarding the effects of point defects on the properties of epitaxial single crystal CuInsb{1-x}Gasb{x}Sesb2 (CIGS) may be drawn. These conclusions may be divided into three categories: the effects of point defects on Ga diffusion and diffusivity, the influence of impurities and alloying elements on doping and mobility, and the effects of impurities on minority carrier recombination kinetics. The diffusivity of Ga into CIGS during growth was found to be strongly dependent of the Cu/In ratio of the growing layer. Diffusivity ranged from a minimum of 2.7×10sp{-13}\\ cmsp2/s at Cu/In = 0.94 to 5 × 10sp{-11} cmsp2/s at Cu/In = 1.41 and 7×10sp{-12} cmsp2/s at Cu/In = 0.43. The diffusion occurred by a vacancy mechanism with Ga, apparently, diffusing through either Cu or In vacancies. The sharp change in diffusivity with changing Cu/In ratio helps to explain the difficulty in maintaining a desired Ga profile in polycrystalline CIGS device absorber layers. Increasing Ga content was found to increase both acceptor and donor density. The decrease in Jsbsc found in Ga-containing polycrystalline devices, is likely caused by a large increase in acceptor density, which may cause less inversion of the surface of the p-type CIGS making the junction more sensitive to surface states. The effect of adding Na by diffusion from either NaOH or Nasp2Se was to reduce the donor density. These results help to explain results in polycrystalline CIGS devices where Na increased hole concentrations, Vsboc, and device efficiency. Unlike Ga and Na, Cr and Se were not found to have any strong effect when added in concentrations ≤10sp{19} cmsp{-3} using ion implantation. The lack of an effect of Se on doping conclusively determines that Na has an effect beyond simply introducing either O or Se into the bulk of the CIGS. While both implanted Se and Cr created large numbers of donors and acceptors before being annealed, both caused a decrease in acceptor concentration after annealing with the effect of Cr being larger than that of Se. Both Se and Cr reduced hole mobility over the entire temperature range investigated. These results imply that CIGS-based devices should be insensitive to accidental transition metal contamination. The steady state photoconductivity of samples which had been ion implanted with Se and Cr, as well as samples which were contaminated with Na by diffusion, was measured. These measurements were made to determine whether contamination by these elements or severe radiation damage affects minority carrier recombination kinetics. In all cases the photoconductivity was found to be unaffected other than by changes in mobility. (Abstract shortened by UMI.)

[Determination of trivalent chromium and hexavalent chromium in dried edible fungi by microwave ashing-liquid chromatography with inductively coupled plasma mass spectrometry].

PubMed

Ni, Zhanglin; Tang, Fubin; Qu, Minghua; Mo, Runhong

2014-02-01

An analytical method using liquid chromatography with inductively coupled plasma mass spectrometry (LC-ICP-MS) for the determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in dried edible fungi was established. Edible fungi sample was ashed by a microwave ashing system and Na2 EDTA was added to the ashing sample to stabilize the Cr(III). An anion exchange column (250 mm x 4.6 mm, 10 microm) with a 60 mmol/L nitric acid (pH 9.3) solution as mobile phase was used for the separation and using ICP-MS as a detector for the determination of trivalent chromium and hexavalent chromium. The calibration curves were linear in the range of 0.5-50 microg/L and the correlation coefficients were 0. 999 9 for Cr(III) and Cr(VI). The average recoveries of Cr(III) and Cr(VI) ranged from 78.0% to 90.7% with the relative standard deviations (RSDs, n = 6) less than 4%. The limits of quantification (LOQ) of Cr(III) and Cr(VI) were 0.5 microg/L. The method is efficient, reliable and sensitive, and can meet the requirement for the determination of Cr(III) and Cr(VI) in dried edible fungi.

Influence of Bulk Chemical Composition on Relative Sensitivity Factors for 55Mn/52Cr by SIMS: Implications for the 53Mn-53Cr Chronometer

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

Matzel, J; Jacobsen, B; Hutcheon, I D

2009-09-09

The {sup 53}Mn-{sup 53}Cr systematics of meteorite samples provide an important high resolution chronometer for early solar system events. Accurate determination of the initial abundance of {sup 53}Mn ({tau}{sub 1/2} = 3.7 Ma) by secondary ion mass spectrometry (SIMS) is dependent on properly correcting for differing ion yields between Mn and Cr by use of a relative sensitivity factor (RSF). Ideal standards for SIMS analysis should be compositionally and structurally similar to the sample of interest. However, previously published Mn-Cr studies rely on few standards (e.g., San Carlos olivine, NIST 610 glass) despite significant variations in chemical composition. We investigatemore » a potential correlation between RSF and bulk chemical composition by determining RSFs for {sup 55}Mn/{sup 52}Cr in 11 silicate glass and mineral standards (San Carlos olivine, Mainz glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, BM90/21-G, and T1-G, NIST 610 glass, and three LLNL pyroxene-composition glasses). All standards were measured on the Cameca ims-3f ion microprobe at LLNL, and a subset were also measured on the Cameca ims-1270 ion microprobe at the Geological Survey of Japan. The standards cover a range of bulk chemical compositions with SiO{sub 2} contents of 40-71 wt.%, FeO contents of 0.05-20 wt.% and Mn/Cr ratios between 0.4 and 58. We obtained RSF values ranging from 0.83 to 1.15. The data obtained on the ims-1270 ion microprobe are within {approx}10% of the RSF values obtained on the ims-3f ion microprobe, and the RSF determined for San Carlos olivine (0.86) is in good agreement with previously published data. The typical approach to calculating an RSF from multiple standard measurements involves making a linear fit to measured {sup 55}Mn/{sup 52}Cr versus true {sup 55}Mn/{sup 52}Cr. This approach may be satisfactory for materials of similar composition, but fails when compositions vary significantly. This is best illustrated by the {approx}30% change in RSF we see between glasses with similar Mn/Cr ratios but variable Fe and Na content. We are developing an approach that uses multivariate analysis to evaluate the importance of different chemical components in controlling the RSF and predict the RSF of unknowns when standards of appropriate composition are not available. Our analysis suggests that Fe, Si, and Na are key compositional factors in these silicate standards. The RSF is positively correlated with Fe and Si and negatively correlated with Na. Work is currently underway to extend this analysis to a wider range of chemical compositions and to evaluate the variability of RSF on measurements obtained by NanoSIMS.« less

Ultrasonic cavitation erosion of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating in NaCl solution.

PubMed

Hong, Sheng; Wu, Yuping; Zhang, Jianfeng; Zheng, Yugui; Qin, Yujiao; Lin, Jinran

2015-09-01

The high-velocity oxygen-fuel (HVOF) spraying process was used to prepare near-nanostructured WC-10Co-4Cr coating. The cavitation erosion behavior and mechanism of the coating in 3.5 wt.% NaCl solution were analyzed in detail. The results showed that the amorphous phase and WC grain were present in the coating. The cavitation erosion resistance of the coating was about 1.27 times that of the stainless steel 1Cr18Ni9Ti under the same testing conditions. The effects of erosion time on the microstructural evolution were discussed. It was revealed that cracks initiated at the edge of pre-existing pores and propagated along the carbide-binder interface, leading to the pull-out of carbide particle and the formation of pits and craters on the surface. The main failure mechanism of the coating was erosion of the binder phases, brittle detachment of hard phases and formation of pitting corrosion products. Copyright © 2015 Elsevier B.V. All rights reserved.

The evaluation of the statistical monomineral thermobarometric methods for the reconstruction of the lithospheric mantle structure

NASA Astrophysics Data System (ADS)

Ashchepkov, I.; Vishnyakova, E.

2009-04-01

The modified versions of the thermobarometers for the mantle assemblages were revised sing statistical calibrations on the results of Opx thermobarometry. The modifications suggest the calculation of the Fe# of coexisting olivine Fe#Ol according to the statistical approximations by the regressions obtained from the xenoliths from kimberlite data base including >700 associations. They allow reproduces the Opx based TP estimates and to receive the complete set of the TP values for mantle xenoliths and xenocrysts. For GARNET Three variants of barometer give similar results. The first is published (Ashchepkov, 2006). The second is calculating the Al2O3 from Garnet for Orthopyroxene according to procedure: xCrOpx=Cr2O3/CaO)/FeO/MgO/500 xAlOpx=1/(3875*(exp(Cr2O3^0.2/CaO)-0.3)*CaO/989+16)-XcrOpx Al2O3=xAlOp*24.64/Cr2O3^0.2*CaO/2.+FeO*(ToK-501)/1002 And then it suppose using of the Al2O3 in Opx barometer (McGregor, 1974). The third variant is transformation of the G. Grutter (2006) method by introducing of the influence of temperature. P=40+(Cr2O3)-4.5)*10/3-20/7*CaO+(ToC)*0.0000751*MgO)*CaO+2.45*Cr2O3*(7-xv(5,8)) -Fe*0.5 with the correction for P>55: P=55+(P-55)*55/(1+0.9*P) Average from this three methods give appropriate values comparable with determined with (McGregor,1974) barometer. Temperature are estimating according to transformed Krogh thermometer Fe#Ol_Gar=Fe#Gar/2+(T(K)-1420)*0.000112+0.01 For the deep seated associations P>55 kbar T=T-(0.25/(0.4-0.004*(20-P))-0.38/Ca)*275+51*Ca*Cr2-378*CaO-0.51)-Cr/Ca2*5+Mg/(Fe+0.0001)*17.4 ILMENITE P= ((TiO2-23.)*2.15-(T0-973)/20*MgO*Cr2O3 and next P=(60-P)/6.1+P ToK is determined according to (Taylor et al , 1998) Fe#Ol_Chr =(Fe/(Fe+Mg)ilm -0.35)/2.252-0.0000351*(T(K)-973) CHROMITE The equations for PT estimates with chromite compositions P=Cr/(Cr+Al)*T(K)/14.+Ti*0.10 with the next iteration P=-0.0053*P^2+1.1292*P+5.8059 +0.00135*T(K)*Ti*410-8.2 For P> 57 P=P+(P-57)*2.75 Temperature estimates are according to the O'Neill- Wall, 1987 The Fe#Ol values are estimated according to three iterations Fe#Ol_Chr=(Fe/Fe+Mg)/4.5-(P-32)*0.00115-0.03 Fe#Ol_Chr =( Fe#Ol -0.074)*0.45+0.086 Fe#Ol _Chr= Fe#Ol -( Fe#Ol -0.06)*(T(K)-1300)*0.000115+0.01 CLINOPYROXENE (Ash2009)=0.32 (1-0.2*Na/Al+0.012*Fe/Na)*Kd ^(3/4)*ToK/(1+Fe)-35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-CaO)*10+Na20/Al2O3* ToK /200 with the second iteration P=(0.0000002* P4 +0.000002+P^3-0.0027*P^2+1.2241*P) The TP estimates were statistically tested wit the available experimental results in peridotite (315 runs) and eclogite (302 runs) system and show good agreement with the TP conditions of runs. The methods are joined together with the other 40 thermometers and 30 barometers for mantle associations in the FORTRAN program allowing simultaneous calculations of 10 pairs of T and P and write the matrix of calculated TPFO2 values together with the compositions of minerals or their formula coefficients. Grant RBRF 05-05-64718.

Corrosion and Mechanical Properties of Al-5 At. Pct Cr Produced by Cryomilling and Subsequent Consolidation at Various Temperatures

NASA Astrophysics Data System (ADS)

Esquivel, J.; Darling, K. A.; Murdoch, H. A.; Gupta, R. K.

2018-04-01

An Al-5 at. pct Cr alloy was produced by high-energy ball milling at liquid nitrogen temperature followed by consolidation using equal-channel axial extrusion at 200 °C, 300 °C and 450 °C. The microstructure and corrosion response were compared with a cast alloy of the same composition. Rather than the intermetallics expected by the phase diagram and seen in the cast alloy, consolidated HEBM alloys exhibited extended solid solubility of Cr in the aluminum matrix in addition to a finely dispersed Cr-rich phase. This led to improvement in the corrosion behavior as investigated via potentiodynamic polarization and constant immersion tests in NaCl solution. Hardness and tensile tests were performed to evaluate the mechanical properties. The highest consolidation temperature (450 °C) contributed to significant grain growth and Cr diffusion, lessening the beneficial effects of processing with HEBM.

Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

NASA Astrophysics Data System (ADS)

Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

2017-11-01

The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

Delay of T cell senescence by caloric restriction in aged long-lived nonhuman primates

PubMed Central

Messaoudi, Ilhem; Warner, Jessica; Fischer, Miranda; Park, Buyng; Hill, Brenna; Mattison, Julie; Lane, Mark A.; Roth, George S.; Ingram, Donald K.; Picker, Louis J.; Douek, Daniel C.; Mori, Motomi; Nikolich-Žugich, Janko

2006-01-01

Caloric restriction (CR) has long been known to increase median and maximal lifespans and to decreases mortality and morbidity in short-lived animal models, likely by altering fundamental biological processes that regulate aging and longevity. In rodents, CR was reported to delay the aging of the immune system (immune senescence), which is believed to be largely responsible for a dramatic increase in age-related susceptibility to infectious diseases. However, it is unclear whether CR can exert similar effects in long-lived organisms. Previous studies involving 2- to 4-year CR treatment of long-lived primates failed to find a CR effect or reported effects on the immune system opposite to those seen in CR-treated rodents. Here we show that long-term CR delays the adverse effects of aging on nonhuman primate T cells. CR effected a marked improvement in the maintenance and/or production of naïve T cells and the consequent preservation of T cell receptor repertoire diversity. Furthermore, CR also improved T cell function and reduced production of inflammatory cytokines by memory T cells. Our results provide evidence that CR can delay immune senescence in nonhuman primates, potentially contributing to an extended lifespan by reducing susceptibility to infectious disease. PMID:17159149

Effect of CeO2 on Cyclic Hot-Corrosion Behavior of Detonation-Gun Sprayed Cr3C2-NiCr Coatings on Ni-Based Superalloy

NASA Astrophysics Data System (ADS)

Saladi, Sekar; Menghani, Jyoti; Prakash, Satya

2015-03-01

The hot-corrosion behavior of detonation-gun sprayed Cr3C2-NiCr coatings with and without 0.4 wt.% CeO2 additive on Ni-based superalloy inconel-718 is comparatively discussed in the present study. Hot-corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60%V2O5 molten salt environment under cyclic heating and cooling conditions on bare and coated superalloys. The thermo-gravimetric technique was used to establish kinetics of hot-corrosion. XRD, FESEM/EDAX, and EDX mapping techniques were used to analyze the corrosion products of bare and coated samples. The results indicate that Cr3C2-NiCr-CeO2-coated superalloy showed better hot-corrosion resistance as compared to bare and Cr3C2-NiCr-coated superalloys. The addition of CeO2 has improved micro-hardness, porosity, and surface roughness values of Cr3C2-NiCr-CeO2 coating. The overall weight gain and parabolic rate constant of Cr3C2-NiCr-CeO2-coated superalloy were found to be lowest in the present study signifying that the addition of CeO2 in Cr3C2-NiCr powder has contributed to the development of adherent and dense oxide scale on the coating at elevated temperature.

Absolute determination of the gelling point of gelatin under quasi-thermodynamic equilibrium.

PubMed

Bellini, Franco; Alberini, Ivana; Ferreyra, María G; Rintoul, Ignacio

2015-05-01

Thermodynamic studies on phase transformation of biopolymers in solution are useful to understand their nature and to evaluate their technological potentials. Thermodynamic studies should be conducted avoiding time-related phenomena. This condition is not easily achieved in hydrophilic biopolymers. In this contribution, the simultaneous effects of pH, salt concentration, and cooling rate (Cr) on the folding from random coil to triple helical collagen-like structures of gelatin were systematically studied. The phase transformation temperature at the absolute invariant condition of Cr = 0 °C/min (T(T)Cr=0) ) is introduced as a conceptual parameter to study phase transformations in biopolymers under quasi-thermodynamic equilibrium and avoiding interferences coming from time-related phenomena. Experimental phase diagrams obtained at different Cr are presented. The T(T)(Cr=0) compared with pH and TT(Cr=0) compared with [NaCl] diagram allowed to explore the transformation process at Cr = 0 °C/min. The results were explained by electrostatic interactions between the biopolymers and its solvation milieu. © 2015 Institute of Food Technologists®

Short and long term modulation of tissue minerals concentrations following oral administration of black cumin (Nigella sativa L.) seed oil to laboratory rats.

PubMed

Basheer, Irum; Qureshi, Irfan Zia

2018-01-15

Nigella sativa, or commonly called black cumin is a small herb of family Ranunculaceae is a well-known medicinal plant but its effects on tissue mineral concentrations of animal bodies is unknown. To study the effect of oral administration of fixed oil of black cumin seeds on tissues mineral content using laboratory rats as experimental model. Experimental animals were exposed to two oral doses of seed oil (60 and 120 ml kg -1 body weight). Short- and long term experiments lasted 24 h and 60 days respectively, with three replicates each. Oil extracted from black cumin seeds was subjected to GC-MS to identify chemical components. Following the wet digestion in nitric acid, samples of whole blood and organs of rats were subjected to atomic absorption spectrophotometry for determination of elements concentrations. Data were compared statistically at p < .05. Compared to control, Cr, Mn, Ni, Cu, Zn showed decrease, whereas Co, Na, Mg and K demonstrated increase, but Ca showed both increase and decrease in most of the tissues upon short term exposure to low and high doses of black cumin oil. During long term exposure, Cr, Fe, Mn, Cu exhibited decrease; Co, Na, Mg and Ca concentrations demonstrated an upregulation, whereas Ni and Zn showed increase and decrease in most of the tissues. Comparison of short term with long term experiments at low dose revealed increases in Fe, Zn, Cu, Mg, K and Ca, a decrease in Cr, Mn, Ni and Cu in most tissues, but both increase and decrease in Na. At high dose, an increase occurred in Fe, Ni, Zn, K, Ca, Mg, a decrease in Cr, while both increase and decrease in Cu, Co and Na concentrations. Our study demonstrates that oral administration of black cumin seeds oil to laboratory rats significantly alters tissue trace elements and electrolytes concentrations. The study appears beneficial but indicates modulatory role of black cumin oil as regards mineral metabolism with far reaching implications in health and disease. Copyright © 2017. Published by Elsevier GmbH.

The onset of metamorphism in ordinary and carbonaceous chondrites

USGS Publications Warehouse

Grossman, J.N.; Brearley, A.J.

2005-01-01

Ordinary and carbonaceous chondrites of the lowest petrologic types were surveyed by X-ray mapping techniques. A variety of metamorphic effects were noted and subjected to detailed analysis using electron microprobe, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and cathodoluminescence (CL) methods. The distribution of Cr in FeO-rich olivine systematically changes as metamorphism increases between type 3.0 and type 3.2. Igneous zoning patterns are replaced by complex ones and Cr-rich coatings develop on all grains. Cr distributions in olivine are controlled by the exsolution of a Cr-rich phase, probably chromite. Cr in olivine may have been partly present as tetrahedrally coordinated Cr3+. Separation of chromite is nearly complete by petrologic type 3.2. The abundance of chondrules showing an inhomogeneous distribution of alkalis in mesostasis also increases with petrologic type. TEM shows this to be the result of crystallization of albite. Residual glass compositions systematically change during metamorphism, becoming increasingly rich in K. Glass in type I chondrules also gains alkalis during metamorphism. Both types of chondrules were open to an exchange of alkalis with opaque matrix and other chondrules. The matrix in the least metamorphosed chondrites is rich in S and Na. The S is lost from the matrix at the earliest stages of metamorphism due to coalescence of minute grains. Progressive heating also results in the loss of sulfides from chondrule rims and increases sulfide abundances in coarse matrix assemblages as well as inside chondrules. Alkalis initially leave the matrix and enter chondrules during early metamorphism. Feldspar subsequently nucleates in the matrix and Na re-enters from chondrules. These metamorphic trends can be used to refine classification schemes for chondrites. Cr distributions in olivine are a highly effective tool for assigning petrologic types to the most primitive meteorites and can be used to subdivide types 3.0 and 3.1 into types 3.00 through 3.15. On this basis, the most primitive ordinary chondrite known is Semarkona, although even this meteorite has experienced a small amount of metamorphism. Allan Hills (ALH) A77307 is the least metamorphosed CO chondrite and shares many properties with the ungrouped carbonaceous chondrite Acfer 094. Analytical problems are significant for glasses in type II chondrules, as Na is easily lost during microprobe analysis. As a result, existing schemes for chondrule classification that are based on the alkali content of glasses need to be revised. ?? The Meteorological Society, 2005.

Pain from the life cycle perspective: Evaluation and Measurement through psychophysical methods of category estimation and magnitude estimation.

PubMed

Sousa, Fátima Aparecida Emm Faleiros; Silva, Talita de Cássia Raminelli da; Siqueira, Hilze Benigno de Oliveira Moura; Saltareli, Simone; Gomez, Rodrigo Ramon Falconi; Hortense, Priscilla

2016-08-18

to describe acute and chronic pain from the perspective of the life cycle. participants: 861 people in pain. The Multidimensional Pain Evaluation Scale (MPES) was used. in the category estimation method the highest descriptors of chronic pain for children/ adolescents were "Annoying" and for adults "Uncomfortable". The highest descriptors of acute pain for children/adolescents was "Complicated"; and for adults was "Unbearable". In magnitude estimation method, the highest descriptors of chronic pain was "Desperate" and for descriptors of acute pain was "Terrible". the MPES is a reliable scale it can be applied during different stages of development. descrever a dor aguda e a crônica na perspectiva do ciclo vital. Métodos: participaram 861 pessoas com dor. Foi utilizada a Escala Multidimensional de Avaliação da Dor (EMADOR). Resultados: no método da estimação de categoria o descritor da dor crônica de maior atribuição para crianças e adolescentes foi "Chata" e para adultos foi "Desconfortável". Os descritores de maior atribuição para dor aguda em crianças e adolescentes foram "Complicada" e em adultos "Insuportável". No método de estimação de magnitude, o descritor de maior atribuição na dor crônica foi "Atormentadora" e na dor aguda foi "Terrível". a EMADOR é uma escala confiável e pode ser utilizada nas diferentes etapas do desenvolvimento humano. la descripción del dolor agudo y crónico desde las perspectiva del ciclo de vida. participaron 861 personas con dolor. Se utilizó la Escala Multidimensional de Evaluación del Dolor (EMEDOR). en el método de estimación de categoría el descriptor de dolor crónico más alto para niños y adolescentes fue de Molesto y para adultos fue Incómodo. Los descriptores mayores de dolor agudo para niños y adolescentes fueron Complejo y para adultos Insoportable. En el método de estimación de magnitud, el mayor descriptor de dolor crónico fueron Atormentador y el mayor de dolor agudo fue Terrible. la EMEDOR es una escala confiable y puede ser utilizada en diferentes etapas de desarrollo.

Neutral complexes as oxidants for the reduced form of parsley (Petroselinum crispum) [2Fe--2S] ferredoxin. Evidence for partial blocking by redox-inactive Cr(III) complexes.

PubMed Central

Adzamli, I K; Kim, H O; Sykes, A G

1982-01-01

The 1 : 1 reactions of three neutral Co(III) oxidants, Co(acac)3, Co(NH3)3(NO2)3 and Co(acac)2(NH3)(NO2), with reduced parsley (Petroselinum crispum) [2Fe--2S] ferredoxin (which carries a substantial negative charge), have been studied at 25 degrees C, pH 8.0 (Tris/HCl), I0.10 (NaCl). Whereas it has previously been demonstrated that with Co(NH3)6+ as oxidant the reaction if completely blocked by redox-inactive Cr(NH3)63+, the neutral oxidants are only partially blocked by this same complex. The effects of three Cr(III) complexes, Cr(NH3)63+%, Cr(en)33+ and (en)2Cr . mu(OH,O2CCH3) . CR(en)24+ have been investigated. Kinetic data for the response of 3+, neutral, as well as 1--oxidants to the presence of 3+ (and 4+) Cr(III) complexes can now be rationalized in terms of a single functional site on the protein for electron transfer. Electrostatics have a significant influence on association at this site. PMID:7115307

[Treatment of wastewater containing Cr(VI) by LDH synthesizing in situ].

PubMed

Chen, Tian-hu; Feng, You-liang; Xu, Hui-fang; Peng, Shu-chuan; Huang, Chuan-hui; Tang, Shu-pei

2004-03-01

The objective of this work was to investigate the efficiency and factors impacting of removal Cr(VI) from wastewater by layer double hydroxide synthesizing in situ. Principle of the method may be described as follow: Mg2+ and Al3+ hydrolysis and forms Mg/Al-LDH by adding Mg2+, Al3+ and NaOH into wastewater containing Cr(VI), Cr(VI) anions are selectively intercalated into interlayer of LDH to balance positive structural charge. While Mg2+ and Al3+ co-precipitates and forms LDH, the Cr(VI) in wastewater is removal by settle of LDH synthesizing in situ, which are confirmed by analysis of X-ray diffraction on settle and chemical analysis on aqueous. The results indicate that factors of impacting on efficiency of removal Cr(VI) include in amount of adding Mg2+ and Al3+, Mg/Al ratio, pH and concentration of Cr(VI) in wastewater. The maximal removal efficiency of Cr(VI) can be reached when pH values are between 8.5 and 9, and Mg/Al ratios are between 1:1 and 2:1, meanwhile, Mg and Al added can be taken good use of. This technology has present extraordinary efficiency of wastewater treatment.

Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter.

PubMed

Sedumedi, Hilda N; Mandiwana, Khakhathi L; Ngobeni, Prince; Panichev, Nikolay

2009-12-30

The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1M Na(2)CO(3) and filtered through hydrophilic PDVF 0.45 microm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 microg g(-1) (cyclone dust), 2710 microg g(-1) (fine dust), and 7800 microg g(-1) (slimes dust) which exceeded the maximum acceptable risk concentration (20 microg g(-1)). The concentration of Cr(VI) in environmental samples of grass (3.4+/-0.2), soil (7.7+/-0.2), and tree bark (11.8+/-1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.

Sodium-chromium covariation in residual clinopyroxenes from abyssal peridotites sampled in the 43°-46°E region of the Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Seyler, Monique; Brunelli, Daniele

2018-03-01

Mantle-derived peridotites sampled at three dredge sites between the Discovery and Indomed fracture zones on the Southwest Indian Ridge axis are analyzed for petrography and major and trace element mineral compositions. While textures and microstructures are those typical of normal residual peridotites these rocks display a large compositional variation encompassing the whole spectrum of abyssal peridotites even at the scale of a single dredge site (≤ 1 km). Particularly, clinopyroxenes in peridotites dredged at 44.03°E show a huge variation in sodium contents positively correlated with chromium concentrations. Observed Nasbnd Cr enrichments exceed the commonly reported contents of the spinel abyssal peridotites. Similar values are also found in very few peridotite samples collected at ultra-slow spreading ridges. Major substitutions governing the compositions of these clinopyroxenes suggest that Nasbnd Cr covariation is caused by a more rapid decrease in Al-Tschermak's molecule with respect to the sodic components jadeite ± kosmochlor, as Cr/Al increases and modal clinopyroxene decreases. We conclude that sodium and chromium enrichments must have occurred contemporaneously with aluminum depletion, i.e., during partial melting. Our modelling suggests that partial, non-modal, melting of a depleted peridotite in association with addition of sodium, by percolation of a Na-rich melt in the upwelling mantle, or Na diffusion from a nearby alkaline melt, may explain this enigmatic and counterintuitive trend. A) SWF-26-2-5: Lherzolite; B) SWF-26-2-7: Harzburgite; C) SWF-26-2-11: Lherzolite; D) SWF-26-2-9: Lherzolite with large pyroxene clusters; E) SWF-27-1-12: Harzburgite. Scale bar = 5 cm. Data show that the compositions of these peridotites do not follow fractional melting trends but plot toward Sm and Ce enrichments relative to Yb at decreasing Yb contents. In the same sampling site, clinopyroxenes highly enriched both in Na2O (> 1 wt.%) and Cr2O3 (> 1.5 wt.%) have higher SmN/YbN ratios (> 0.8) than clinopyroxenes poorer in Na and Cr. The two clinopyroxenes having the highest SmN/YbN (2.1, 2.4) and CeN/YbN (0.8, 1.8) ratios have REE patterns indicating of equilibration with an alkaline basalt or a melt derived from a garnet-bearing source [e.g., EDUL Dr6-1-2, Seyler et al. (2011) and PS55-90-20, Hellebrand and Snow (2003)]. However, CeN/YbN ratios do not increase linearly with increasing Na2O and/or Cr2O3. In EDUL peridotites, trends of increasing SmN/YbN and CeN/YbN vs YbN can be modelled by near-batch melting of a depleted spinel peridotite influxed with a melt derived from a garnet-bearing source (Brunelli et al., 2014). SWF-26 peridotites do not follow the same trends as EDUL Dr6 and Arctic peridotites, suggesting different melting conditions and/or interaction with different melt compositions.

Improvement of Corrosion Resistance of Binary Mg-Ca Alloys Using Duplex Aluminum-Chromium Coatings

NASA Astrophysics Data System (ADS)

Daroonparvar, Mohammadreza; Yajid, Muhamad Azizi Mat; Yusof, Noordin Mohd; Bakhsheshi-Rad, Hamid Reza; Adabi, Mohsen; Hamzah, Esah; Kamali, Hussein Ali

2015-07-01

Al-AlCr was coated on Mg-Ca and Mg-Zn-Ce-La alloys using physical vapor deposition method. The surface morphology of the specimens was characterized by x-ray diffraction, scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and atomic force microscopy (AFM). The AFM results indicated that the average surface roughness of Al-AlCr coating on the Mg-Ca alloy is much lower than that of Al-AlCr coating on the Mg-Zn-Ce-La alloy. However, Al-AlCr coating on the Mg-Ca alloy presented a more compact structure with fewer pores, pinholes, and cracks than Al-AlCr coating on the Mg-Zn-Ce-La alloy. Electrochemical studies revealed that the novel coating (Al-AlCr) can remarkably reduce the corrosion rate of the Mg-Ca alloy in 3.5 wt.% NaCl solution. It was seen that the anodic current density of the Al-AlCr-coated Mg-Ca alloy was very small when compared to the Al-AlCr-coated Mg-Zn-Ce-La and uncoated alloys. Impedance modulus ( Z) of the Al-AlCr-coated samples was higher than that of the bare Mg alloys. Z of Al-AlCr-coated Mg-Ca alloy was higher than that of the Al-AlCr-coated Mg-Zn-Ce-La alloy at low frequency.

Microstructural analyses of Cr(VI) speciation in chromite ore processing Residue (COPR)

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

CHRYSOCHOOU, MARIA; FAKRA, SIRINE C .; Marcus, Matthew A.

2010-03-01

The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30percent of its total Cr(VI) (6000 mg/kg) as large crystals(>20 ?m diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50percent of themore » Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogarnet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmilleritewasalso likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogarnet and hydrotalcite being the main Cr(VI) binding phases. Treatment ofHBCOPRis challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to ~;;50percent of Cr(VI) in GB COPR.« less

Donor-Specific Indirect Pathway Analysis Reveals a B-Cell-Independent Signature Which Reflects Outcomes in Kidney Transplant Recipients

PubMed Central

Haynes, L. D.; Jankowska-Gan, E.; Sheka, A.; Keller, M. R.; Hernandez-Fuentes, M. P.; Lechler, R. I.; Seyfert-Margolis, V.; Turka, L. A.; Newell, K. A.; Burlingham, W. J.

2012-01-01

To investigate the role of donor-specific indirect pathway T cells in renal transplant tolerance, we analyzed responses in peripheral blood of 45 patients using the trans-vivo delayed-type hypersensitivity assay. Subjects were enrolled into five groups—identical twin, clinically tolerant (TOL), steroid monotherapy (MONO), standard immunosuppression (SI) and chronic rejection (CR)—based on transplant type, posttransplant immunosuppression and graft function. The indirect pathway was active in all groups except twins but distinct intergroup differences were evident, corresponding to clinical status. The antidonor indirect pathway T effector response increased across patient groups (TOL < MONO < SI < CR; p < 0.0001) whereas antidonor indirect pathway T regulatory response decreased (TOL > MONO = SI > CR; p < 0.005). This pattern differed from that seen in circulating naïve B-cell numbers and in a cross-platform biomarker analysis, where patients on monotherapy were not ranked closest to TOL patients, but rather were indistinguishable from chronically rejecting patients. Cross-sectional analysis of the indirect pathway revealed a spectrum in T-regulatory:T-effector balance, ranging from TOL patients having predominantly regulatory responses to CR patients having predominantly effector responses. Therefore, the indirect pathway measurements reflect a distinct aspect of tolerance from the recently reported elevation of circulating naïve B cells, which was apparent only in recipients off immunosuppression. PMID:22151236

Cyclic oxidation behavior of some plasma-sprayed coatings in Na2SO4-60%V2O5 environment

NASA Astrophysics Data System (ADS)

Singh, Harpreet; Prakash, Satya; Puri, Devendra; Phase, D. M.

2006-12-01

Cyclic oxidation behavior of plasma-sprayed NiCrAlY, Ni-20Cr, Ni3Al, and Stellite-6 coatings was investigated in an aggressive environment of Na2SO4-60%V2O5 by thermogravimetric techniques for 50 cycles. These coatings were deposited on a Ni-base superalloy, namely Superni 600; 10Fe-15.5Cr-0.5Mn-0.2C-Bal Ni (wt.%). X-ray diffraction, scanning electron microscopy/energy dispersive x-ray (SEM/EDX), and electron probe microanalyzer (EPMA) techniques were used to analyze the oxidation products. The uncoated superalloy suffered accelerated oxidation in the form of intense spallation of its oxide scale. After deposition of the NiCrAlY coating, the superalloy showed a minimum mass gain, whereas after application of the Stellite-6 coating, a maximum mass gain was observed among the coatings studied. All of the coatings were found to be useful in reducing the spallation of the substrate superalloy. Moreover, the coatings were successful in maintaining continuous surface contact with the base superalloy during the cyclic oxidation. The phases revealed for the oxidized coatings were mainly the oxides of chromium and/or aluminum and the spinels containing nickel-chromium/cobalt-chromium/nickel-aluminum mixed oxides, which are reported to be protective against high-temperature oxidation/hot corrosion.

Anode materials for lithium ion batteries

DOEpatents

Abouimrane, Ali; Amine, Khalil

2017-04-11

An electrochemical device includes a composite material of general Formula (1-x)J-(x)Q wherein: J is a metal carbon alloy of formula Sn.sub.zSi.sub.z'Met.sub.wMet'.sub.w'C.sub.t; Q is a metal oxide of formula A.sub..gamma.M.sub..alpha.M'.sub..alpha.'O.sub..beta.; and wherein: A is Li, Na, or K; M and M' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; Met and Met' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; 0

One- and two-electron reduced 1,2-diketone ligands in [CrIII(L*)3] (S = 0) and Na2(Et2O)2[VIV(LRed)3] (S = 1/2).

PubMed

Spikes, Geoffrey H; Sproules, Stephen; Bill, Eckhard; Weyhermüller, Thomas; Wieghardt, Karl

2008-12-01

The electronic structures of chromium and vanadium centers coordinated by three reduced 1,2-diketones have been elucidated by using density functional theory (DFT) calculations and a host of physical methods: X-ray crystallography; cyclic voltammetry; ultraviolet-visible (UV-vis), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) spectroscopy; and magnetic susceptibility measurements. The metal center in octahedral [CrIII(L*)3]0 (1), a CrIII (d3) ion is coupled antiferromagnetically to three monoanionic ligand pi-radicals affording an S ) 0 ground state. In contrast, Na2(Et2O)2[VIV(LRed)3] (2) (S ) 1/2), possesses a central VIV (d1) ion O,OE-coordinated to three closed-shell, doubly reduced ligands which in turn are coordinated by two Na cations enforcing a trigonal prismatic geometry at the vanadium center. 2 can be oxidized electrochemically by one and two electrons generating a monoanion, [V(L)3]1-, and a neutral species, [V(L)3]0, respectively. DFT calculations atthe B3LYP level show that the one-electron oxidized product contains an octahedral VIV ion coupled antiferromagnetically to one monoanionic ligand pi-radical [VIV(L*)(LRed)2]1- (S ) 0). In contrast, the two-electron oxidized product contains a VIII ion coupled antiferromagnetically to three ligand pi-radicals in an octahedral field[VIII(L*)3]0 (S ) 1/2).

Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal.

PubMed

Korak, Julie A; Huggins, Richard; Arias-Paic, Miguel

2017-07-01

Due to stricter regulations, some drinking water utilities must implement additional treatment processes to meet potable water standards for hexavalent chromium (Cr(VI)), such as the California limit of 10 μg/L. Strong base anion exchange is effective for Cr(VI) removal, but efficient resin regeneration and waste minimization are important for operational, economic and environmental considerations. This study compared multiple regeneration methods on pilot-scale columns on the basis of regeneration efficiency, waste production and salt usage. A conventional 1-Stage regeneration using 2 N sodium chloride (NaCl) was compared to 1) a 2-Stage process with 0.2 N NaCl followed by 2 N NaCl and 2) a mixed regenerant solution with 2 N NaCl and 0.2 N sodium bicarbonate. All methods eluted similar cumulative amounts of chromium with 2 N NaCl. The 2-Stage process eluted an additional 20-30% of chromium in the 0.2 N fraction, but total resin capacity is unaffected if this fraction is recycled to the ion exchange headworks. The 2-Stage approach selectively eluted bicarbonate and sulfate with 0.2 N NaCl before regeneration using 2 N NaCl. Regeneration approach impacted the elution efficiency of both uranium and vanadium. Regeneration without co-eluting sulfate and bicarbonate led to incomplete uranium elution and potential formation of insoluble uranium hydroxides that could lead to long-term resin fouling, decreased capacity and render the resin a low-level radioactive solid waste. Partial vanadium elution occurred during regeneration due to co-eluting sulfate suppressing vanadium release. Waste production and salt usage were comparable for the 1- and 2-Stage regeneration processes with similar operational setpoints with respect to chromium or nitrate elution. Published by Elsevier Ltd.

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.

Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

DOE PAGES

Xiong, Yongliang

2015-05-06

In this article, solubility measurements of lead carbonate, PbCO 3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO 3 up to I = 1.2 mol•kg –1 and in the mixtures of NaHCO 3 and Na 2CO 3 up to I = 5.2 mol•kg –1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log K sp) for cerussite, PbCO 3(cr) = Pb 2+ + CO 3 2- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO 3(aq), Pb(CO 3) 2more » 2-, and Pb(CO 3)Cl – with the bulk-supporting electrolytes, based on the Pitzer model. The model developed in this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.« less

Purification and characterization of a salt-tolerant cellulase from the mangrove oyster, Crassostrea rivularis.

PubMed

An, Tianchen; Dong, Zhu; Lv, Junchen; Liu, Yujun; Wang, Manchuriga; Wei, Shuangshuang; Song, Yanting; Zhang, Yingxia; Deng, Shiming

2015-04-01

A cellulase with wide range of pH resistance and high salt tolerance was isolated from the digestive gland of the oyster Crassostrea rivularis living in mangrove forests. The 27 kDa cellulase named as CrCel was purified 40.6 folds by anion exchange chromatography and extraction from the gel after non-reducing sodium dodecylsufate-polyacrylamide gel electrophoresis. The specific activity of the purified cellulase was 23.4 U/mg against carboxymethyl cellulose (CMC). The N-terminal amino acid sequence of CrCel was determined to be NQKCQANSRV. CrCel preferably hydrolyzes β-1,4-glucosidic bonds in the amorphous parts of cellulose materials and displays degradation activity toward xylan. The Km and Vmax values of CrCel for CMC were determined to be 2.1% ± 0.4% and 73.5 ± 3.3 U mg(-1), respectively. The optimal pH value and temperature of CrCel were 5.5 and 40°C, respectively. The enzyme was stable in a wide range of pH, retaining over 60% activity after incubation for 80 min in the pH range of 3.0-9.0. In addition, CrCel showed remarkable tolerance to salt and remained active at high NaCl concentrations, but also retained over 70% activity after incubation in 0.5-2 M NaCl for up to 24 h. On the basis of the N-terminal sequence alignment and its similar properties to other animal cellulases, CrCel was regarded as a member of glycosyl hydrolase family 45 β-1,4-glucanases. CrCel is the first reported cellulase isolated from mangrove invertebrates, which suggests that it may participate in the assimilation of cellulolytic materials derived from the food sources of the oyster and contribute to the consumption of mangrove primary production. The unique properties of this enzyme make it a potential candidate for further industrial application. © The Author 2015. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.

Inclusions of crichtonite-group minerals in Cr-pyropes from the Internatsionalnaya kimberlite pipe, Siberian Craton: Crystal chemistry, parageneses and relationships to mantle metasomatism

NASA Astrophysics Data System (ADS)

Rezvukhin, Dmitriy I.; Malkovets, Vladimir G.; Sharygin, Igor S.; Tretiakova, Irina G.; Griffin, William L.; O'Reilly, Suzanne Y.

2018-05-01

Cr-pyrope xenocrysts and associated inclusions of crichtonite-group minerals from the Internatsionalnaya kimberlite pipe were studied to provide new insights into processes in the lithospheric mantle beneath the Mirny kimberlite field, Siberian craton. Pyropes are predominantly of lherzolitic paragenesis (Cr2O3 2-6 wt%) and have trace-element spectra typical for garnets from fertile mantle (gradual increase in chondrite-normalized values from LREE to MREE-HREE). Crichtonite-group minerals commonly occur as monomineralic elongated inclusions, mostly in association with rutile, Mg-ilmenite and Cr-spinel within individual grains of pyrope. Sample INT-266 hosts intergrowth of crichtonite-group mineral and Cl-apatite, while sample INT-324 contains polymineralic apatite- and dolomite-bearing assemblages. Crichtonite-group minerals are Al-rich (1.1-4.5 wt% Al2O3), moderately Zr-enriched (1.3-4.3 wt% ZrO2), and are Ca-, Sr-, and occasionally Ba-dominant in terms of A-site occupancy; they also contain significant amounts of Na and LREE. T-estimates and chemical composition of Cr-pyropes imply that samples represent relatively low-T peridotite assemblages with ambient T ranging from 720 to 820°С. Projected onto the 35 mW/m2 cratonic paleogeotherm for the Mirny kimberlite field (Griffin et al., 1999b. Tectonophysics 310, 1-35), temperature estimates yield a P range of 34-42 kbar ( 110-130 km), which corresponds to a mantle domain in the uppermost part of the diamond stability field. The presence of crichtonite-group minerals in Cr-pyropes has petrological and geochemical implications as evidence for metasomatic enrichment of some incompatible elements in the lithospheric mantle beneath the Mirny kimberlite field. The genesis of Cr-pyropes with inclusions of crichtonite-group minerals is attributed to the percolation of Ca-Sr-Na-LREE-Zr-bearing carbonate-silicate metasomatic agents through Mg- and Cr-rich depleted peridotite protoliths. The findings of several potentially new members of the crichtonite group as inclusions in garnet extend existing knowledge on the compositions and occurrences of exotic titanates stable in the lithospheric mantle.

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.

Development of a Multi-Species Biotic Ligand Model Predicting the Toxicity of Trivalent Chromium to Barley Root Elongation in Solution Culture

PubMed Central

Song, Ningning; Zhong, Xu; Li, Bo; Li, Jumei; Wei, Dongpu; Ma, Yibing

2014-01-01

Little knowledge is available about the influence of cation competition and metal speciation on trivalent chromium (Cr(III)) toxicity. In the present study, the effects of pH and selected cations on the toxicity of trivalent chromium (Cr(III)) to barley (Hordeum vulgare) root elongation were investigated to develop an appropriate biotic ligand model (BLM). Results showed that the toxicity of Cr(III) decreased with increasing activity of Ca2+ and Mg2+ but not with K+ and Na+. The effect of pH on Cr(III) toxicity to barley root elongation could be explained by H+ competition with Cr3+ bound to a biotic ligand (BL) as well as by the concomitant toxicity of CrOH2+ in solution culture. Stability constants were obtained for the binding of Cr3+, CrOH2+, Ca2+, Mg2+ and H+ with binding ligand: log KCrBL 7.34, log KCrOHBL 5.35, log KCaBL 2.64, log KMgBL 2.98, and log KHBL 4.74. On the basis of those estimated parameters, a BLM was successfully developed to predict Cr(III) toxicity to barley root elongation as a function of solution characteristics. PMID:25119269

Development of a multi-species biotic ligand model predicting the toxicity of trivalent chromium to barley root elongation in solution culture.

PubMed

Song, Ningning; Zhong, Xu; Li, Bo; Li, Jumei; Wei, Dongpu; Ma, Yibing

2014-01-01

Little knowledge is available about the influence of cation competition and metal speciation on trivalent chromium (Cr(III)) toxicity. In the present study, the effects of pH and selected cations on the toxicity of trivalent chromium (Cr(III)) to barley (Hordeum vulgare) root elongation were investigated to develop an appropriate biotic ligand model (BLM). Results showed that the toxicity of Cr(III) decreased with increasing activity of Ca(2+) and Mg(2+) but not with K(+) and Na(+). The effect of pH on Cr(III) toxicity to barley root elongation could be explained by H(+) competition with Cr(3+) bound to a biotic ligand (BL) as well as by the concomitant toxicity of CrOH(2+) in solution culture. Stability constants were obtained for the binding of Cr(3+), CrOH(2+), Ca(2+), Mg(2+) and H(+) with binding ligand: log KCrBL 7.34, log KCrOHBL 5.35, log KCaBL 2.64, log KMgBL 2.98, and log KHBL 4.74. On the basis of those estimated parameters, a BLM was successfully developed to predict Cr(III) toxicity to barley root elongation as a function of solution characteristics.

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

NASA Astrophysics Data System (ADS)

Zolotov, Mikhail Yu.

2012-08-01

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance of methane cannot be fairly estimated.

Oxidation behavior of Cr(III) during thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides.

PubMed

Mao, Linqiang; Gao, Bingying; Deng, Ning; Liu, Lu; Cui, Hao

2016-02-01

The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Universal single grain amphibole thermobarometer for mantle rocks - preliminary calibration.

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor

2017-04-01

Calibration of S-Al- K-Na-Ca distribution in the structure of the mantle amphiboles (Cr- hornblende, pargasite, kaersutite) using experimental data (Niida, Green, 1999; Wallace Green, 1991, Conceicao, Green, 2004; Medard et al, 2006; Safonov, Butvina, 2013; 2016; Pirard, Hermann, 2015 etc) allows to obtain an equation for pressure estimates in 0.5 - 4.5 GPa interval. Regression calculated pressures with experimental values (R 0.82) and precision 5 kbar allow to use barometer for a wide range of mantle rocks from peridotite to pyroxenites and megacrystals. For the higher pressures (Cr- pargasite richterite) calibration is carried by the cross- correlations with the estimates calculated for the natural associations obtained using clino- and orthopyroxene. IT was used KD =Si/(8-Al-2.2*Ti)*(Na+K))/Ca for the following equation: P(GPa)=0.0035*(4+K/(Na+K))*2*Mg)/Fe+3.75*(K+Na)/Ca))*KD*ToK**0.75/ (1+3.32*Fe)-ln(1273/ToK*5*(8*Mg-Al*2 +3*Ti+8*Cr+3*K)/10 Th advantage of this barometer comparing with the previous (Ridolfi, Renzulli, 2012) is that is working with all mantle amphibole types. For the calculations of the PT parameters of the natural xenocrysts it was used monomineral version of Gar-Amph termometer (Ravna et al., 2000) in combination with the received barometer. Contents of Ca- Mg and Fe in associated garnets were calculated usinf the regressions obtained from natural and experimental associations. Aplication of the mantle amphibole thermobarometry for the reconstruction of sections of the cratonic mantle lithosphere of Yakutia show that amphibloles are distributed in various parts of mantle sections in deifferent mantle terranes of Yakutia. The most abundant amphoboles from Alakite region are distributed within all mantle section. In the SCLM beneat Yubileyaya pipe thehalf of them belong to the spinel garnet facie refering to the upper pyroxenitic suit and Cr- hornblende - mica viens. The second group reffer to the eclogite pyroxenite layer in the middle part of SCLM and the third group refer to richterites form the depleted manle peridotites. In SCLM beneat the Sytykanskaya they are more frequent and trace through all the mantle layers. In SCLM beneat the Aykhal they mostly are from the lower and in Komsomolskaya from the middle SCLM parts. In Daldyn field rare amdphibles from Dalnaya are Fe- enriched pargasites belonging to the Ilm bearing peridotites in middle SCLM part as well as in SCLM beneath thr Udachnaya. But there are Fe- low amphiboles substitutng the orthopyroxenes. In Zarnitsa the Cr - hornblendes occur in shallow garnet pyroxenites. One deep seated richterite substitute garnet grains. Rare amphiboles were detedted in Mirninsky filed in Internatiolnaya pipe and reffer to the resorbed and deformed granets from the Garnet -Spinel facies and from 4.0 GPa boundary. Amphiboles are frequent in the SCLM from the northern part of Siberian craton. In SCLM beneath the Kharmai the Fe- encriched varietes are from the Moho boundary. Common Cr-pargasite occurs to 3 GPa in Obnazhennay, pipe, Kharamai field In mantle SCLM beneath Obnazhennaya pipe and circum Anabr region friquent Cr- pargasies and horblendes refer to the relatively hot branch of mantle lithosphere and probably corresponds to the Triassic mantle reactivation. Mantle Cr- hornbleneds occurs on most upper part of the mantle column beneath Quaternary mujeritic Bartoy vocanoes in Transbaikal. The pargasites and kaersutites in this locality refer to more heated conditions and could be found to 2.0 GPa. Grant RFBR 16.-05-000860

Reductive solidification/stabilization of chromate in municipal solid waste incineration fly ash by ascorbic acid and blast furnace slag.

PubMed

Zhou, Xian; Zhou, Min; Wu, Xian; Han, Yi; Geng, Junjun; Wang, Teng; Wan, Sha; Hou, Haobo

2017-09-01

Fly ash is a hazardous byproduct of municipal solid waste incineration (MSWI). Cementitious material that is based on ground-granulated blast furnace slag (GGBFS) has been tested and proposed as a binder to stabilize Pb, Cd, and Zn in MSWI fly ash (FA). Cr, however, still easily leaches from MSWI FA. Different reagents, such as ascorbic acid (VC), NaAlO 2 , and trisodium salt nonahydrate, were investigated as potential Cr stabilizers. The results of the toxicity characteristic leaching procedure (TCLP) showed that VC significantly improved the stabilization of Cr via the reduction of Cr(VI) to Cr(III). VC, however, could interfere with the hydration process. Most available Cr was transformed into stable Cr forms at the optimum VC content of 2 wt%. Cr leaching was strongly pH dependent and could be represented by a quintic polynomial model. The results of X-ray diffraction and scanning electron microscopy-energy dispersive analysis revealed that hollow spheres in raw FA were partially filled with hydration products, resulting in the dense and homogeneous microstructure of the solidified samples. The crystal structures of C-S-H and ettringite retained Zn and Cr ions. In summary, GGBFS-based cementitious material with the low addition of 2 wt% VC effectively immobilizes Cr-bearing MSWI FA. Copyright © 2017. Published by Elsevier Ltd.

Cross sections for He and Ne isotopes in natural Mg, Al, and Si, He isotopes in CaF2, Ar isotopes in natural Ca, and radionuclides in natural Al, Si, Ti, Cr, and stainless steel induced by 12- to 45-MeV protons

NASA Technical Reports Server (NTRS)

Walton, J. R.; Heymann, D.; Yaniv, A.; Edgerley, D.; Rowe, M. W.

1976-01-01

Stacks of thin Mg, Al, Si, Ca, CaF2, Ti, and stainless steel foils were bombarded in twelve irradiations by a variable energy cyclotron. Cross sections are reported for He and Ne in natural Mg, Al, and Si, and for He in CaF2, and for Ar in natural Ca, as determined from mass spectrometer analysis of the inert gases. In addition, cross sections of Na-22 in natural Al and Si, of V-48 in natural Ti, and of Cr-51, Mn-52, and Co-57 in stainless steel are reported. From these were deduced Cr-51 and Mn-52 cross sections in natural Cr.

Electrochromic material and electro-optical device using same

DOEpatents

Cogan, Stuart F.; Rauh, R. David

1992-01-01

An oxidatively coloring electrochromic layer of composition M.sub.y CrO.sub.2+x (0.33.ltoreq.y.ltoreq.2.0 and x.ltoreq.2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M.sub.y CrO.sub.2+x provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li.sup.+ ion conductors.

Electrochromic material and electro-optical device using same

DOEpatents

Cogan, S.F.; Rauh, R.D.

1992-01-14

An oxidatively coloring electrochromic layer of composition M[sub y]CrO[sub 2+x] (0.33[le]y[le]2.0 and x[le]2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M[sub y]CrO[sub 2+x] provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li[sup +] ion conductors. 12 figs.

Soft X-ray laser using pumping of 3P and 4P levels of He-like and H-like ions

DOEpatents

Hagelstein, Peter L.

1987-01-01

X-ray laser method and apparatus for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4-50 cm.sup.-1.

Soft x-ray laser using pumping of 3p and 4p levels of He-like and H-like ions

DOEpatents

Hagelstein, P.L.

1985-07-05

X-ray laser method and apparatus for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4 to 50 cm/sup -1/.

Soft x-ray laser using pumping of 3P and 4P levels of He-like and H-like ions

DOEpatents

Hagelstein, P.

1982-03-26

X-ray laser method and apparatus for producing coherent radiation at, for example, energies of 40 to 189 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like rare gases or N, O, F, or C gases, with associated laser transition gains of 20 to 50 cm/sup -1/.

[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.

Silver Nanoparticle-Enhanced Resonance Raman Sensor of Chromium(III) in Seawater Samples.

PubMed

Ly, Nguyễn Hoàng; Joo, Sang-Woo

2015-04-29

Tris(hydroxymethyl)aminomethane ethylenediaminetetraacetic acid (Tris-EDTA), upon binding Cr(III) in aqueous solutions at pH 8.0 on silver nanoparticles (AgNPs), was found to provide a sensitive and selective Raman marker band at ~563 cm-1, which can be ascribed to the metal-N band. UV-Vis absorption spectra also supported the aggregation and structural change of EDTA upon binding Cr(III). Only for Cr(III) concentrations above 500 nM, the band at ~563 cm-1 become strongly intensified in the surface-enhanced Raman scattering spectra. This band, due to the metal-EDTA complex, was not observed in the case of 50 mM of K+, Cd2+, Mg2+, Ca2+, Mn2+, Co2+, Na+, Cu2+, NH4+, Hg2+, Ni2+, Fe3+, Pb2+, Fe2+, and Zn2+ ions. Seawater samples containing K, Mg, Ca, and Na ion concentrations higher than 8 mM also showed the characteristic Raman band at ~563 cm-1 above 500 nM, validating our method. Our approach may be useful in detecting real water samples by means of AgNPs and Raman spectroscopy.

Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

NASA Astrophysics Data System (ADS)

Sato, Y.; Ogasawara, Y.

2015-12-01

Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz lamella-bearing garnet (relatively high Na2O: 0.03-0.06 wt.%) contains inclusions of Omp and Zrn and oriented lamellae of Qtz, Rt and Ap. These suggest eclogitic origins deeper than groups E and F. Above features in garnets from the Garnet Ridge constrain their formations by multistage and wide range intensity of metasomatisms underneath the Colorado Plateau.

The correlation between cellulose allomorphs (I and II) and conversion after removal of hemicellulose and lignin of lignocellulose.

PubMed

Song, Yanliang; Zhang, Jingzhi; Zhang, Xu; Tan, Tianwei

2015-10-01

H2SO4, NaOH and H3PO4 were applied to decompose lignocellulose samples (giant reeds, pennisetum and cotton stalks) to investigate the correlation between cellulose allomorphs (cellulose I and II) and conversion of cellulose. The effect of removal of hemicellulose and lignin on the surface morphology, crystallinity index (CrI), cellulose allomorphs (cellulose I and II), and enzymatic hydrolysis under different pretreatments was also studied. CrI caused by H3PO4 pretreatment reached 11.19%, 24.93% and 8.15% for the three samples, respectively. Corn stalk showed highest conversion of cellulose among three samples, irrespective of the pretreatment used. This accounted for the widely use of corn stalk as the renewable crop substrate to synthesize biofuels like ethanol. CrI of cellulose I (CrI-I) negatively affects cellulose conversion but CrI of cellulose II (CrI-II) positively affects cellulose conversion. It contributes to make the strategy to transform cellulose I to cellulose II and enhancing enzymatic hydrolysis of lignocellulose. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of substrate bias voltages on impact resistance of CrAlN coatings deposited by modified ion beam enhanced magnetron sputtering

NASA Astrophysics Data System (ADS)

Chunyan, Yu; Linhai, Tian; Yinghui, Wei; Shebin, Wang; Tianbao, Li; Bingshe, Xu

2009-01-01

CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. The effect of substrate negative bias voltages on the impact property of the CrAlN coatings was studied. The X-ray diffraction (XRD) data show that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1), (2 0 0) (2 2 0) and (2 2 2) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing substrate bias voltage the coatings became more compact and denser, and the microhardness and fracture toughness of the coatings increased correspondingly. In the dynamic impact resistance tests, the CrAlN coatings displayed better impact resistance with the increase of bias voltage, due to the reduced emergence and propagation of the cracks in coatings with a very dense structure and the increase of hardness and fracture toughness in coatings.

The Characteristic and Activation of Mixed Andisol Soil/Bayat Clays/Rice Husk Ash as Adsorbent of Heavy Metal Chromium (Cr)

NASA Astrophysics Data System (ADS)

Pranoto; Sajidan; Suprapto, A.

2017-02-01

Chromium (Cr) concentration in water can be reduced by adsorption. This study aimed to determine the effect of Andisol soil composition/Bayat clay/husk ash, activation temperature and contact time of the adsorption capacity of Cr in the model solution; the optimum adsorption conditions and the effectiveness of ceramic filters and purifiers to reduce contaminant of Cr in the water. The mixture of Andisol soil, Bayat clay, and husk ash is used as adsorbent of metal ion of Cr(III) using batch method. The identification and characterisation of adsorbent was done with NaF test, infrared spectroscopy (FTIR), X-ray diffraction (XRD). Cr metal concentrations were analyzed by atomic absorption spectroscopy. Sorption isotherms determined by Freundlich equation and Langmuir. The optimum conditions of sorption were achieved at 150°C activation temperature, contact time of 30 minutes and a composition Andisol soil / Bayat clay / husk ash by comparison 80/10/10. The results show a ceramic filter effectively reduces total dissolved solids (TDS) and Chromium in the water with the percentage decrease respectively by 75.91% and 9.44%.

Opto-EM and Devices Investigation

DTIC Science & Technology

1989-06-01

value of bandwidth is used the signal to noise ratio of the UAM system becomes ( SNP )u z exp ’cr. 2P,\\ 3 .V N._ W/ 3.3 GAUSSIAN SHAPED MESSAGE SPECTRA...Unclassified N/A 2a. SECURITY CLASSIFICATION AUTHORITY 3 . DISTRIBUTION/AVAILABILITY OF REPORT N/A Approved for public release; 2b. DECLASSIFICATION...Synthesis, Single Crystal Growth, Purification and Characterization of Indium Phosphide 2. Deposition of Select Silicides Under High Vacuum Conditions 3 . Use

Fabrication and Assessment of Crumb-Rubber-Modified Coatings with Anticorrosive Properties

PubMed Central

Al-Aqeeli, Nasser

2015-01-01

Scrap tires continue to be a major source of waste due to the lack of valuable and effective disposal routes. A viable solution to this problem is to recycle crumb rubber (CR)—a granulated material derived from scrap tires—and use it to develop other valuable products. Herein we report the fabrication and characterization of CR-modified coatings with anticorrosive properties on metal substrates. By varying the particle size and concentration of CR, we have determined the coating composition that offers the highest level of erosion protection. Images from a scanning electron microscope (SEM) reveal that CR is homogenously dispersed in the coating, especially when fine particles are used. As the concentration of CR increases, the hardness of the coating decreases as a result of the elastic properties of CR. More importantly, the erosion rate of the coating decreases due to increased ductility. Following Potentiodynamic tests, the utilization of these coatings proved to be beneficial as they showed good protection against aqueous corrosion when tested in 0.5 M NaCl solution. Our newly developed coatings offer an incentive to recycling CR and open up a safe and sustainable route to the disposal of scrap tires. PMID:28787931

Fabrication and Assessment of Crumb-Rubber-Modified Coatings with Anticorrosive Properties.

PubMed

Al-Aqeeli, Nasser

2015-01-06

Scrap tires continue to be a major source of waste due to the lack of valuable and effective disposal routes. A viable solution to this problem is to recycle crumb rubber (CR)-a granulated material derived from scrap tires-and use it to develop other valuable products. Herein we report the fabrication and characterization of CR-modified coatings with anticorrosive properties on metal substrates. By varying the particle size and concentration of CR, we have determined the coating composition that offers the highest level of erosion protection. Images from a scanning electron microscope (SEM) reveal that CR is homogenously dispersed in the coating, especially when fine particles are used. As the concentration of CR increases, the hardness of the coating decreases as a result of the elastic properties of CR. More importantly, the erosion rate of the coating decreases due to increased ductility. Following Potentiodynamic tests, the utilization of these coatings proved to be beneficial as they showed good protection against aqueous corrosion when tested in 0.5 M NaCl solution. Our newly developed coatings offer an incentive to recycling CR and open up a safe and sustainable route to the disposal of scrap tires.

Reduced Noise UV Enhancement of Etch Rates for Nuclear Tracks in CR-39

NASA Astrophysics Data System (ADS)

Sheets, Rebecca; Clarkson, David; Ume, Rubab; Regan, Sean; Sangster, Craig; Padalino, Stephen; McLean, James

2016-10-01

The use of CR-39 plastic as a Solid State Nuclear Track Detector is an effective technique for obtaining data in high-energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched in NaOH at 80°C for 6 hours, producing micron-scale signal pits at the nuclear track sites. Using CR-39 irradiated with 5.4 MeV alpha particles and 1.0 MeV protons, we show that exposing the CR-39 to high intensity UV light before etching, with wavelengths between 240 nm and 350 nm, speeds the etch process. Elevated temperatures during UV exposure amplifies this effect, with etch rates up to 50% greater than unprocessed conditions. CR-39 pieces exposed to UV light and heat can also exhibit heightened levels of etch-induced noise (surface features not caused by nuclear particles). By illuminating the CR-39 from the side opposite to the tracks, a similar level of etch enhancement was obtained with little to no noise. The effective wavelength range is reduced, due to strong attenuation of shorter wavelengths. Funded in part by a LLE contract through the DOE.

Degradation of phenol and Cr (VI) wastewater with contact glow discharge electrolysis method and the addition of Fe2+

NASA Astrophysics Data System (ADS)

Kurniawan, Raden Ridzki Aditya; Saksono, Nelson

2017-11-01

Phenol and Cr (VI) are an organic waste and dangerous heavy metals which generated from a wide variety of industrial processes such as textiles, paints, dyes, and others. For that reason, we need effective waste treatment technologies, one of them is Contact Glow Discharge Electrolysis (CGDE). This method produce reactive species such as radical hidroxyl so as to be able to degradate phenol and Cr(VI) wastewater effectively. This research aims to obtain the effect of Fe 2+ and air bubbles in degradation of phenol and Cr (VI) waste simultaneously. Waste degradation is measured its absorbance with UV-Vis spectrophotometer. In the conditions of 600 Volt voltage, Na2SO4 0.02 M, anode depth of 1.5 cm, the addition of Fe2+ 40 ppm and the addition of air bubbles for 30 minutes was obtained a percentage degradation of phenol 99.47%, Cr (VI) 76.75% and specific energy of 344.473 kJ / mmol.

Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

NASA Technical Reports Server (NTRS)

Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

1999-01-01

Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

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.

Microstructure and hot corrosion behavior of the Ni-based superalloy GH202 treated by laser shock processing

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

Cao, Jiangdong

The effects of laser shock processing on microstructure, the residual stress, and hot corrosion behavior of the Ni-based superalloy GH202 were investigated. The microstructures of GH202 before and after laser shock processing (LSP) were characterized by electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). A large number of crystal defects (twins, dislocation arrays, and high dense tangles) were generated on the surface of GH202 treated with LSP. The cross-sectional compressive residual stress and micro-hardness of specimens treated by LSP were improved significantly. The corrosion kinetics of GH202 with or without LSP treatment at 800 °C and 900 °C weremore » investigated. Analysis by X-ray diffraction (XRD) revealed that the corrosion products mainly consist of Cr{sub 2}O{sub 3}, TiO{sub 2}, Al{sub 2}O{sub 3}, NiO, CrS, Ni{sub 3}S{sub 2}, and Na{sub 2}CrO{sub 4}. The surface and cross-section morphologies were observed by scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS). The results confirmed that the crystal defects induced by LSP promotes the creation of diffusion paths for elements (Cr, Al, and Ti), allowing the formation of tiny homogeneous oxidation films in a very short time. Additionally, the spallation of oxidation film on the treated specimens was alleviated significantly. Overall, the hot corrosion resistance of Ni-based GH202 induced by LSP was improved in Na{sub 2}SO{sub 4} and NaCl molten salt from 800 °C to 900 °C. - Highlights: • Microstructure changes of GH202 before and after LSP were observed by EBSD and TEM. • The hardness and residual compressive stress after LSP were significantly increased. • The increased diffusion paths for elements helped to form oxidation films quickly. • Hot corrosion resistance of GH202 after LSP was significantly improved.« less

The excretion of biotrace elements using the multitracer technique in tumour-bearing mice.

PubMed

Wang, X; Tian, J; Yin, X M; Zhang, X; Wang, Q Z

2000-12-01

A radioactive multitracer solution obtained from the nuclear reaction of selenium with 25 MeV/nucleon 40Ar ions was used for investigation of trace element excretion into the faeces and urine of cancerous mice. The excretion rates of 22 elements (Na, K, Rb, Mg, Ca, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Mo, Nb, Tc, Ru, Ag and In) were simultaneously measured under strictly identical experimental conditions, in order to clarify the excretion behavior of these elements in cancerous mice. The faecal and urinary excretion rates of Mg, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Nb, Ru and Mo in cancerous mice, showed the in highest value at 0-8 hours. The accumulative excretion of Ca, Mo, Y and Zr was decreased and Na, Fe, Mn and Co increased in tumour-bearing mice, when compared to normal mice.

Redox equilibria of multivalent ions in silicate glasses

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Morris, R. V.

1977-01-01

Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu(2+) to Eu(3+) in various glasses formed by rapidly quenching silicate liquids. The compositional field studied comprised mixtures of SiO2, TiO2, Al2O3, CaO, MgO, and Na2O. The proposed model describes the Eu(2+)/Eu(3+) ratio over the entire compositional field in terms of parameters easily related to each glass composition. The general applicability and utility of the model is further demonstrated by its application to the Fe(2+)-Fe(3+), Ce(3+)-Ce(4+), and Cr(3+)-Cr(6+) redox reactions in binary alkali oxide silicate glasses of Li, Na, and K.

The Universal Cpx Jd-Di barometer for mantle peridotite eclogite and pyroxenites and it using for the mantle petrology

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor

2015-04-01

The Jd-Di exchange in clinopyroxenes used for the calibration of pyroxene barometer (Ashchepkov, 2000;2002; Ashchepkov et al 2010;2011;2012) was transformed to make one universal equation for mantle peridotite eclogites and pyroxenites. The original barometer (Ashchepkov, 2002) calibrated on pressures produced by Opx barometry (McGregor , 1974) was transformed (Ashchepkov et al ., 2004; 2010; 2011) to satisfy the increasing data bases for the mantle xenoliths and experimental values 530 in peridotitic and 650 in elcogitic systems . The obtained difference Pd =Pcpx- Pexp were studied for the dependence on each component and their combination . Instead of the common activities we used the temperature-dependent empirical equations. The three separate equations for the common peridotites, pyroxenites and eclogites (Ashchepkov et al., 2010) were checked and complex To and Al-Na-Fe dependent universal coefficients were received. The KD is determined as follows: KD=Na/AlCr*Mg/Ca The logarithmic dependence between P and KD was transformed to a linear one. Final pressure equations are: AlCr=(Al-0.01) *((T-600)/700)**0.75+Cr*(ToK-100)/1000+(4*Ti-0.0125)/ (T0-801)*650 +0.55*((Fe-0.23) *(T0-900)/10000-K) P=0.26*(5+12*(Al+0.30*Na)KD* ToK**0.75 /(1+Fe+ Fe*(ToK-600)/1000)-ln(1273/ ToK))*40*(7*Na-Al-15*Ti+10*Cr+Mg/4)+7.5*Si-20*( Al*Na*Mg/Ca/(Al-2*Ti+Na-2*Fe/(Fe+Mg))+50*(Na+0.1*Al-2*Ti+0.05*Mg-0.22*Ca-0.7*Na)/Ca). Obtained equation in combination with the (Nimis,Taylor, 2000) thermometer allow to reconstruct position of the magma feeder systems of the alkali basaltic magma withing the mantle diapirs in modern platforms like in Vitim plateau (Ashchepkov et al., 2011) and now was applicated to reconstruct the deep seated magma conduits beneath the mountain collision systems, island arcs ocean plateaus etc. This equation allows to receive the positions of the major groups of eclogites mantle sections and to find out the regularities of their behavior. The Fe rich eclogites commonly trace he boundary between the lower upper part of subcontinental lithospheric mantle (SCLM) at 3 -4 GPa marking pyroxenite eclogites layer. Ca- rich eclogites and especially grospydites in SCLM beneath Precambrian kimberlites occurs near pyroxenite layer but in younger mantle sections they became common in the lower parts marking presence of the subducted sediments. The Mg Cr- less group eclogites commonly diamondiferous and referring to the ancient island arc complexes are also common in the middle part of mantle sections and near 5-6 GPa. The group is often dominated in the young kimberlites and sometimes is highly diamondiferous. Commonly P-Fe# for eclogites in the lower SCLM part show rising Fe# with decreasing pressures which very of then reflect the differentiation of the magmatic systems commonly rather significant. Commonly the Fe#-values for the eclogites show that they can't be simple subucted oceanic basalts but material remelted not only during the low angle "hot"subduction but also under the influence of the kimberlite melts including protokimberlite magmas. The Mg - rich and Fe rich pyroxenites also show the extending in pressures trends which suggest the anatexic melting under the influence of volatiles or under the plum magma hybridization. RBRF grants 05-05-64718, 03-05-64146; 11 -05-00060a; 11-05-91060-PICS. Projects 77-2, 65-03, 02-05 IGM SD RAS and ALROSA Stock Company.

Efficacy of Er,Cr:YSGG Laser in Removing Smear Layer and Debris with Two Different Output Powers

PubMed Central

Bolhari, Behnam; Ehsani, Sara; Etemadi, Ardavan; Shafaq, Mohammad

2014-01-01

Abstract Objective: The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls. Background data: Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space. Methods: Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers. Results: The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas. Conclusions: This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers. PMID:25198390

Efficacy of Er,Cr:YSGG laser in removing smear layer and debris with two different output powers.

PubMed

Bolhari, Behnam; Ehsani, Sara; Etemadi, Ardavan; Shafaq, Mohammad; Nosrat, Ali

2014-10-01

The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls. Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space. Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers. The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas. This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers.

Cr(III) solubility in aqueous fluids at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Watenphul, Anke; Schmidt, Christian; Jahn, Sandro

2014-02-01

Trivalent chromium is generally considered relatively insoluble in aqueous fluids and melts. However, numerous counterexamples in nature indicate Cr(III) mobilization by aqueous fluids during metamorphism or hydrothermal alteration of chromite-bearing rocks, or by pegmatite melts. So far, very little is known about the chromium concentrations and speciation in such fluids. In this study, the solubility of eskolaite (Cr2O3) in 1.6-4.2 m aqueous HCl solutions was determined in situ at elevated pressures up to 1 GPa and temperatures ranging between 400 and 700 °C using synchrotron micro-X-ray fluorescence spectroscopy (μ-XRF). Determined concentrations of dissolved Cr ranged between about 900-18,000 ppm, with the highest concentrations found at 500 °C and 861 MPa. The Cr(III) solubility in aqueous HCl fluids is retrograde in the studied temperature range and increases with pressure. In addition, Cr(III) complexation in these fluids was explored by Raman spectroscopy on a 12.3 mass% HCl fluid in equilibrium with eskolaite at 400 and 600 °C, 0.3-1.6 GPa. All spectra show two prominent Cr-Cl stretching bands at about 275 and 325 cm-1, which display some fine structure, and in some spectra weak bands in the region between 380 and 500 cm-1. The sum of the integrated intensities of the two dominant bands reveals qualitatively the same changes with temperature along an isochore, with pressure at constant temperature, and with the time required for equilibration as the Cr(III) concentrations in the fluid determined by μ-XRF. Complementary ab initio molecular dynamics simulations of a 4 m HCl solution at two different densities (0.8 and 0.97 g/cm3) and temperatures (427 and 727 °C) were performed to investigate the vibrational properties of various(O)y3-x and (O)y(OH)z3-x-z complexes with 3⩽x+z⩽4 and 0⩽y⩽2. Quasi-normal mode analysis reveals that both the tetrahedral symmetric and antisymmetric Cr-Cl stretching vibrations of CrCl4(H2O)0-2- have characteristic frequencies in the range of the two strongest experimentally observed Raman bands, whereas Cr-O stretching vibrations of hydroxy-chloride complexes occur at wavenumbers above 400 cm-1. Solubility and complexation of Cr(III) depend strongly on the activities of Cl- and H+. At high H+ and Cl- activity, the results are consistent with CrCl(H2O)0-2-1-0 complexes as major Cr(III) species, the Cr coordination number of which increases with pressure by becoming more aquated. At low Cl- activity, i.e. in our study at high-temperature low-pressure conditions, the data indicate mixed CrClx((OH)z3-x-z complexes with Cl-Cr ratios less than three. In situ μ-XRF solubility experiments conducted with eskolaite + (H2O + 29 mass% Na2CO3) and kosmochlor + (H2O + 44 mass% Na2Si3O7) resulted in dissolved Cr concentrations at or below the detection limit of 500 ppm. Thus, acidic chloridic fluids seem to be more efficient agents for Cr(III) mobilization and transport at crustal conditions than aqueous alkali carbonate or silicate solutions.

Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California

USGS Publications Warehouse

Stohlgren, Thomas J.; Melack, John M.; Esperanza, Anne M.; Parsons, David J.

1991-01-01

Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride (Cl-) were the major anions in bulk precipitation with volume-weighted average concentrations of 12.6, 12.3 and 10.0 μeq/1, respectively. Annual inputs of NO3-N, NH4-N and SO4-S from wet deposition were about 60 to 75% of those reported from bulk deposition collectors. Discharge from the two watersheds occurs primarily during spring snowmelt. Solute exports from Log and Tharp's Creeks were dominated by HCO3-, Ca2+ and Na+, while H+, NO3-, NH4+ and PO43- outputs were relatively small. Solute concentrations were weakly correlated with instantaneous stream flow for all solutes (r2 3- (Log Cr. r2=0.72; Tharp's Cr. r2=0.38), Na+ (Log Cr. r2=0.56; Tharp's Cr. r2=0.47), and silicate (Log Cr. r2=0.71; Tharp's Cr. r2=0.49). Mean annual atmospheric contributions of NO3-N (1.6 kg ha-1), NH4-N (1.7 kg ha-1), and SO4-S (1.8 kg ha-1), which are associated with acidic deposition, greatly exceed hydrologic losses. Annual watershed yields (expressed as eq ha-1) of HCO3- exceeded by factors of 2.5 to 37 the annual atmospheric deposition of H+.

Increased N-Acetylaspartate/creatine ratio in the medial prefrontal cortex among unmedicated obsessive-compulsive disorder patients.

PubMed

Fan, Qing; Tan, Ling; You, Chao; Wang, Jijun; Ross, Colin A; Wang, Xuemei; Zhang, Tianhong; Li, Jianqi; Chen, Kemin; Xiao, Zeping

2010-10-01

Changes in the fronto-striato-thalamo-cortical-circuit loop have been suggested in the pathogenesis of obsessive-compulsive disorder (OCD), and have been studied using (1)H magnetic resonance spectroscopy ((1)H MRS) with interesting findings. However, whether neural metabolites are abnormal in the medial prefrontal cortex in patients with OCD is unknown. The purpose of the present study was to investigate neural metabolites in this brain region in a sample of patients with OCD. Subjects were 21 unmedicated OCD patients, including 10 who were drug-naïve, and 19 healthy controls. Single-voxel (1)H MRS was used to study the medial prefrontal cortex for each subject. Levels of N-acetylaspartate (NAA), choline-containing compounds and myoinositol were measured in terms of their ratios with creatine (Cr). The NAA/Cr ratio was significantly higher among OCD patients than among healthy controls (F = 4.76, P = 0.037). However, it did not correlate with patients' symptoms or with their illness durations. The NAA/Cr ratio also did not differ between drug-naïve and previously medicated patients. No significant group differences were found between OCD patients and normal controls for the choline-containing compounds/Cr or myoinositol/Cr ratios. In addition, a significant correlation between the NAA/Cr ratio and trait anxiety scores on the State-Trait Anxiety Inventory was found among the controls (r = 0.639, P = 0.010). The N-Acetylaspartate level relative to creatine in the medial prefrontal cortex was increased among unmedicated OCD patients. This cannot be attributed to the effect of medications. The possible significance of this finding in the pathophysiology of OCD is discussed. © 2010 Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine. Psychiatry and Clinical Neurosciences © 2010 Japanese Society of Psychiatry and Neurology.

CrMAPK3 regulates the expression of iron-deficiency-responsive genes in Chlamydomonas reinhardtii.

PubMed

Fei, Xiaowen; Yu, Junmei; Li, Yajun; Deng, Xiaodong

2017-05-16

Under iron-deficient conditions, Chlamydomonas exhibits high affinity for iron absorption. Nevertheless, the response, transmission, and regulation of downstream gene expression in algae cells have not to be investigated. Considering that the MAPK pathway is essential for abiotic stress responses, we determined whether this pathway is involved in iron deficiency signal transduction in Chlamydomonas. Arabidopsis MAPK gene sequences were used as entry data to search for homologous genes in Chlamydomonas reinhardtii genome database to investigate the functions of mitogen-activated protein kinase (MAPK) gene family in C. reinhardtii under iron-free conditions. Results revealed 16 C. reinhardtii MAPK genes labeled CrMAPK2-CrMAPK17 with TXY conserved domains and low homology to MAPK in yeast, Arabidopsis, and humans. The expression levels of these genes were then analyzed through qRT-PCR and exposure to high salt (150 mM NaCl), low nitrogen, or iron-free conditions. The expression levels of these genes were also subjected to adverse stress conditions. The mRNA levels of CrMAPK2, CrMAPK3, CrMAPK4, CrMAPK5, CrMAPK6, CrMAPK8, CrMAPK9, and CrMAPK11 were remarkably upregulated under iron-deficient stress. The increase in CrMAPK3 expression was 43-fold greater than that in the control. An RNA interference vector was constructed and transformed into C. reinhardtii 2A38, an algal strain with an exogenous FOX1:ARS chimeric gene, to silence CrMAPK3. After this gene was silenced, the mRNA levels and ARS activities of FOX1:ARS chimeric gene and endogenous CrFOX1 were decreased. The mRNA levels of iron-responsive genes, such as CrNRAMP2, CrATX1, CrFTR1, and CrFEA1, were also remarkably reduced. CrMAPK3 regulates the expression of iron-deficiency-responsive genes in C. reinhardtii.

Polyethylenimine functionalized Fe3O4/steam-exploded rice straw composite as an efficient adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Zhang, Shengli; Wang, Zhikai; Chen, Haoyu; Kai, Chengcheng; Jiang, Man; Wang, Qun; Zhou, Zuowan

2018-05-01

Polyethyleneimine functionalized Fe3O4/steam-exploded rice straw composite (Fe3O4-PEI-SERS), which combines magnetic separation with adsorption of PEI functionalized biosorbent, was successfully prepared via a simple glutaraldehyde crosslinking method. Its adsorption potential for the removal of Cr(VI) was systematically studied in batch mode. Results showed that Cr(VI) adsorption on Fe3O4-PEI-SESERS was highly pH-dependent, and the optimum pH was 2.0. The time to reach equilibrium was related to initial Cr(VI) concentration and was 1 and 6 h for 200 and 300 mg/L of Cr(VI), respectively. The adsorption system followed pseudo-second-order kinetic model and Langmuir isotherm. Its maximum adsorption capacity was 280.11, 317.46 and 338.98 mg/g at 25, 35 and 45 °C, respectively. The competitive uptake from coexisting ions (K+, Na+, Cu2+, Cl- and NO3-) was insignificant except SO42-. After six adsorption/desorption cycles, the adsorbent retained good adsorption capacity. The Cr(VI) removal involved its partial reduction into Cr(III). Due to the properties of high adsorption capacity, strong magnetic responsiveness, good reusability and Cr(VI) detoxification, the Fe3O4-PEI-SESERS has a potential application in Cr(VI) removal from wastewater.

The oxidation of Cr(III) to Cr(VI) in the environment by atmospheric oxygen during the bush fires.

PubMed

Panichev, N; Mabasa, W; Ngobeni, P; Mandiwana, K; Panicheva, S

2008-05-30

The presence of Cr(VI) in soils and plants of remote unpolluted areas can be explained by partial oxidation of Cr(III) with atmospheric oxygen during seasonable bush fires, which are rather frequent event in South Africa. Experiments with thermal treatment of a veld grass, Hyperthelia dissoluta, in muffle furnace at high temperature, followed by electrothermal atomic absorption spectrometry (ETAAS) determination of chromium, show a remarkable increase in Cr(VI) concentration from initial 2.5 to 23.2% after the treatment of grass ash at 500 degrees C and to 58.1% at 900 degrees C. Before ETAAS determination, the two chromium species of interest were separated by the treatment of samples with 0.1M Na2CO3. Thermodynamic calculations confirm the possibility of Cr(III) to Cr(VI) oxidation with atmospheric oxygen at high temperature in alkaline media, which is typical for vegetation ash. Analysis of field samples show that percent of Cr(VI), in respect to the total amount of chromium increased from initial 2.5% in grass to 9.3% in ash of grass. Without oxidation the percent of Cr(VI) in grass and ash of grass should be a constant value. After the fire Cr(VI) concentration in top soil (0-3 cm) increased from 0.3+/-0.05 to 1.8+/-0.5 microg g(-1) and the total Cr from 26+/-9 to 69+/-14 microg g(-1). The reason for the appearance of additional amount of Cr on top soil can be explained by condensation of chromium species from flame and shouldering ash on a soil surface. The results of studies demonstrate that Cr(VI) is formed by Cr(III) oxidation with atmospheric oxygen at high temperature during bush fires.

N-Acetylaspartate Reduction in the Medial Prefrontal Cortex Following 8 weeks of Risperidone Treatment in First-Episode Drug-Naïve Schizophrenia Patients

PubMed Central

Zong, Xiaofen; Hu, Maolin; Li, Zongchang; Cao, Hongbao; He, Ying; Liao, Yanhui; Zhou, Jun; Sang, Deen; Zhao, Hongzeng; Tang, Jinsong; Lv, Luxian; Chen, Xiaogang

2015-01-01

It is unclear whether N-acetylaspartate (NAA) depletions documented in schizophrenia patients might be due to the disease progression or medications. Here we investigated longitudinal NAA changes in drug-naïve first-episode patients (FEP) who are relatively free from chronicity. Forty-two drug-naïve FEP and 38 controls were enrolled in this study to explore the effect of 8-week risperidone monotherapy on NAA. All spectra were obtained from the medial prefrontal cortex (MPFC) on a 3.0 T MRI and analyzed with LCModel. At baseline, patients presented no significant differences in NAA (P = 0.084) or NAA/Cr + Pcr (P = 0.500) compared to controls; NAA levels were negatively correlated with PANSS total scores (P = 0.001) and WCST-PE (P = 0.041). After treatment, patients demonstrated significant reductions of NAA (P < 0.001) and NAA/Cr + Pcr (P < 0.001), and significant improvement in PANSS-P (P < 0.001) and PANSS-G (P < 0.001) symptoms. We detected no significant correlations between NAA alterations and PANSS-P (P = 0.679) or PANSS-G (P = 0.668) symptom changes; nor did NAA/Cr + Pcr changes with alterations in PANSS-P (P = 0.677) and PANSS-G (P = 0.616). This is the first evidence that short-term risperidone treatment induces an acute reduction of MPFC NAA during the early phase of schizophrenia, which may be a previously unavailable biomarker to indicate risperidone with a similar pharmacological mechanism, although the functional significance is still unclear. PMID:25778460

Tracing potential soil contamination in the historical Solvay soda ash plant area, Jaworzno, Southern Poland.

PubMed

Sutkowska, Katarzyna; Teper, Leslaw; Stania, Monika

2015-11-01

This study of soil conditions was carried out on 30 meadow soil (podzol) samples from the vicinity of the soda ash heap in Jaworzno, supplemented by analyses of 18 samples of waste deposited on the heap. In all samples, the total content of macroelements (Ca and Na) and heavy metals (Cd, Cr, Ni, Pb and Zn) as well as pH were analysed. The element concentrations were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The materials examined were neutral to ultra-alkaline. Total accumulations (mg kg(-1)) of chemical elements in the soil vary from 130.24 to 14076.67 for Ca, 41.40-926.23 for Na, 0.03-3.34 for Cd, 0.94-103.62 for Cr, 0.94-35.89 for Ni, 3.51-76.47 for Pb and 12.05-279.13 for Zn, whereas quantities of the same elements in the waste samples vary from 171705.13 to 360487.94 for Ca, 517.64-3152.82 for Na, 0.2-9.89 for Cd, 1.16-20.40 for Cr, 1.08-9.79 for Ni, 0.1-146.05 for Pb and 10.26-552.35 for Zn. The vertical distribution of the metals was determined in each soil profile. Despite enrichment of heavy metals in the uppermost horizon on the top of the heap, the results lead to the conclusion that the relation of historical production of soda ash in Jaworzno to current contamination of the local soil environment is insignificant.

Effect of Ginseng on Calretinin Expression in Mouse Hippocampus Following Exposure to 835 MHz Radiofrequency

PubMed Central

Aryal, Bijay; Maskey, Dhiraj; Kim, Myeung-Ju; Yang, Jae-Won; Kim, Hyung-Gun

2011-01-01

Exponential rise in the use of mobile communication devices has generated health concerns due to radiofrequency (RF) exposure due to its close proximity to the head. Calcium binding proteins like calretinin regulate the levels of calcium (Ca2+) which plays an important role in biological systems. Ginseng is known for maintaining equilibrium in the human body and may play a beneficial radioprotectant role against electromagnetic field (EMF) exposure. In the present study, we evaluated the radioprotective effects of red ginseng (RG) extract in a mouse model. Calretinin (CR) expression was measured using a free-floating immunohistochemical method in the hippocampus of mice after 835 MHz EMF exposure for 5 h/d for 5 d at specific absorption rate=1.6 W/kg for the different experimental groups. The control animals were treated with NaCl while the experimental animals received 10 mg/kg ginseng, or 30 mg/kg; EMF exposed mice were also treated with NaCl, 10 mg/kg ginseng (E10), or 30 mg/kg (E30). Decreases in CR immunoreactivity (IR) along with loss of CA1 and CA3 interneurons and infragranular cells were observed in the ENaCl group while such losses were not observed in the E10 and E30 groups. CR IR significantly increased in the RG-treated group compared to control and EMF-exposed groups treated with NaCl. The study demonstrates that RG extract can serve as a radioprotective agent that maintains Ca2+ homeostasis and prevents neuronal loss in the brain hippocampal region caused by RF exposure. PMID:23717055

Chemical passivation as a method of improving the electrochemical corrosion resistance of Co-Cr-based dental alloy.

PubMed

Rylska, Dorota; Sokołowski, Grzegorz; Sokołowski, Jerzy; Łukomska-Szymańska, Monika

2017-01-01

The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment. The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM. The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification. Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.

Evaluation of extraction methods for hexavalent chromium determination in dusts, ashes, and soils

USGS Publications Warehouse

Wolf, Ruth E.; Wilson, Stephen A.

2010-01-01

One of the difficulties in performing speciation analyses on solid samples is finding a suitable extraction method. Traditional methods for extraction of hexavalent chromium, Cr(VI), in soils, such as SW846 Method 3060A, can be tedious and are not always compatible with some determination methods. For example, the phosphate and high levels of carbonate and magnesium present in the U.S. Environmental Protection Agency (USEPA) Method 3060A digestion for Cr(VI) were found to be incompatible with the High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) detection method used by our laboratory. Modification of Method 3060A by eliminating the use of the phosphate buffer provided improved performance with the detection method, however dilutions are still necessary to achieve good chromatographic separation and detection of Cr(VI). An ultrasonic extraction method using a 1 mM Na2CO3 - 9 mM NaHCO3 buffer solution, adapted from Occupational Safety and Health Administration (OSHA) Method ID215, has been used with good results for the determination of Cr(VI) in air filters. The average recovery obtained for BCR-545 - Welding Dust Loaded on Filter (IRMM, Belgium) using this method was 99 percent (1.2 percent relative standard deviation) with no conversion of Cr(VI) to Cr(III) during the extraction process. This ultrasonic method has the potential for use with other sample matrices, such as ashes and soils. Preliminary investigations using NIST 2701 (Hexavalent Chromium in Contaminated Soil) loaded onto quartz filters showed promising results with approximately 90 percent recovery of the certified Cr(VI) value. Additional testing has been done using NIST 2701 and NIST 2700 using different presentation methods. Extraction efficiency of bulk presentation, where small portions of the sample are added to the bottom of the extraction vessel, will be compared with supported presentation, where small portions of the sample are loaded onto a quartz filter prior to extraction. In addition, results obtained from the standard grinding preparation of NIST 2701 and NIST 2700 will be compared with micronizing to reduce particle size before extraction.

The effect of Cr2O3 doping on structures and dielectric constants of SiO2-Bi2O3-B2O3-Na2CO3 glass based on silica gel of natural sand

NASA Astrophysics Data System (ADS)

Diantoro, M.; Zaini, M. B.; Muniroh, Z.; Nasikhudin; Hidayat, A.

2017-05-01

One of the abundant natural resources along the coastal lines of Indonesia is silica sand. One of the beaches which has a lot of silica content is Bancar-Tuban beach. Silica can be used as a raw material of glass that has multiple properties in optic, dielectric, and other physical properties by introducing specific dopants. Some oxides have been used as dopant e.g. Al2O3, Fe3O4, and NiO. However, there has not been any comprehensive study discussing the multiple properties of natural silica-sand-based glass with Cr2O3 dopant so far. A series of samples have been prepared, which mean two solid steps to state melting technique. Cr2O3 was selected as a dopant due to its potential to control its color and to increase the dielectric constant of the glass. The synthesis of silica (SiO2) sand from BancarTuban beach was conducted through the sol-gel process. The composition varied as the addition of Cr2O3on 50SiO2-25B2O3-(6.5-x) Bi2O3-18.5Na2CO3-xCr2O3 (x = 0, 0.02, 0.04, 0.06 and 0.08mol), later called SBBN glass. The samples’ characterizations of the structure and morphology were conducted through the use of XRD, and SEM-EDX. The measurements were done by using a DC capacitance meter in order to investigate the dielectric properties of the sample, under the influence of light. It is shown that addition of Cr2O3 did not alter the crystal structure but changed the structure of the functional bond formation. It is also revealed that the dielectric constant increased along with the increasing of Cr2O3. An interesting result was that the dielectric constant of the glass was quantized decreasingly as the increase of light.

Cr(VI) removal by FeS-coated alumina, silica, and natural sand

NASA Astrophysics Data System (ADS)

Park, M.; Lee, S.; Jeong, H. Y.

2014-12-01

Removal of Cr(VI) was investigated using mackinawite (FeS)-coated mineral sorbents under anoxic conditions. The sorbents included alumina (Al), silica (WS), and natural sand (NS). By analysis of both solution and solid phases, all FeS-coated sorbents were found to reduce Cr(VI) into Cr(III). The sorption extent and mechanism of Cr(VI) strongly depended on the pH conditions. Only at pH 4.5, significant amounts of the dissolved Cr remained in the solution. Titration of dissolved Cr(III) and Fe(III) by NaOH solutions indicated that no bulk-phase precipitation occurred at pH 4.5. Also, the removal of Cr(VI) at pH 4.5 was the greatest by FeS-coated NS. Consistent with these, Cr-K edge EXAFS revealed that Cr was removed by FeS-coated NS via surface precipitation, and that it was immobilized by FeS-coated WS and Al by forming surface clusters. Regardless of FeS-coated sorbents, at pH 7.0 and pH 9.5, the initially added Cr(VI) was quantitatively removed from the solution phase. By EXAFS analysis, the Cr sorption by FeS-coated Al was mainly due to the bulk-phase precipitation of Cr(OH)3(s) or [Cr, Fe](OH)3(s). In case of FeS-coated WS and NS, the short Cr-Cr distance (~2.6 Å) at pH 7.0 and pH 9.5 was not simply accounted for by the bulk precipitation as either hydroxide (rCr-Cr ~ 3.0 Å), and it would rather result from the surface precipitation. Such a difference in the coordination structure among FeS-coated sorbents was likely due to in the lower surface area of the former available for the surface precipitation.

Increased Concentrations of Glutamate and Glutamine in Normal-Appearing White Matter of Patients with Multiple Sclerosis and Normal MR Imaging Brain Scans

PubMed Central

Tisell, Anders; Leinhard, Olof Dahlqvist; Warntjes, Jan Bertus Marcel; Aalto, Anne; Smedby, Örjan; Landtblom, Anne-Marie; Lundberg, Peter

2013-01-01

In Multiple Sclerosis (MS) the relationship between disease process in normal-appearing white matter (NAWM) and the development of white matter lesions is not well understood. In this study we used single voxel proton ‘Quantitative Magnetic Resonance Spectroscopy’ (qMRS) to characterize the NAWM and thalamus both in atypical ‘Clinically Definite MS’ (CDMS) patients, MRIneg (N = 15) with very few lesions (two or fewer lesions), and in typical CDMS patients, MRIpos (N = 20) with lesions, in comparison with healthy control subjects (N = 20). In addition, the metabolite concentrations were also correlated with extent of brain atrophy measured using Brain Parenchymal Fraction (BPF) and severity of the disease measured using ‘Multiple Sclerosis Severity Score’ (MSSS). Elevated concentrations of glutamate and glutamine (Glx) were observed in both MS groups (MRIneg 8.12 mM, p<0.001 and MRIpos 7.96 mM p<0.001) compared to controls, 6.76 mM. Linear regressions of Glx and total creatine (tCr) with MSSS were 0.16±0.06 mM/MSSS (p = 0.02) for Glx and 0.06±0.03 mM/MSSS (p = 0.04) for tCr, respectively. Moreover, linear regressions of tCr and myo-Inositol (mIns) with BPF were −6.22±1.63 mM/BPF (p<0.001) for tCr and −7.71±2.43 mM/BPF (p = 0.003) for mIns. Furthermore, the MRIpos patients had lower N-acetylaspartate and N-acetylaspartate-glutamate (tNA) and elevated mIns concentrations in NAWM compared to both controls (tNA: p = 0.04 mIns p<0.001) and MRIneg (tNA: p = 0.03 , mIns: p = 0.002). The results suggest that Glx may be an important marker for pathology in non-lesional white matter in MS. Moreover, Glx is related to the severity of MS independent of number of lesions in the patient. In contrast, increased glial density indicated by increased mIns and decreased neuronal density indicated by the decreased tNA, were only observed in NAWM of typical CDMS patients with white matter lesions. PMID:23613944

Defining and Assessing the Impact to the Combat/Weapon Systems of a Ship Post Major Overhaul

DTIC Science & Technology

2013-06-01

vig ati on...ch  Ra da r ( SP S‐6 7)   Un ne ce ss ary  fo r M iss ion   0 Lik e t o h av e  0.2 5 FA LS E 0 0 Na vig ati on  Da ta  (W SN ‐7 )  Ne ce ss ar y  0.5...E 0 0 Na vig ati on  Di str ibu tio n ( NA VS SI)   Ne ce ss ar y  0.5 Ne ce ss ary   0.5 FA LS E 0 0 Cr itic al  Na vig ati on  D ist rib ut ion

Searching for “LiCrIIPO4”

NASA Astrophysics Data System (ADS)

Mosymow, E.; Glaum, R.; Kremer, R. K.

2014-10-01

The two new phosphates LiCrII4(PO4)3 and Li5CrII2CrIII(PO4)4 are discovered as equilibrium phases (ϑ=800 °C) in the quarternary system Li/Cr/P/O. Their crystal structures have been determined from single-crystal X-ray diffraction data {LiCrII4(PO4)3: violet-blue, Pnma (no. 62), Z=4, a=6.175(1) Å, b=14.316(3) Å, c=10.277(2) Å, 100 parameters, R1=0.028, wR2=0.08, 2060 unique reflections with Fo>4σ(Fo); Li5CrII2CrIII(PO4)4: greyish-green, P1bar (no. 2), Z=1, a=4.9379(7) Å, b=7.917(2) Å, c=8.426(2) Å, α=109.98(2)°, β=90.71(1)°, γ=104.91(1)°, 131 parameters, R1=0.022, wR2=0.067, 1594 unique reflections with Fo>4σ(Fo)}. Li5CrII2CrIII(PO4)4 adopts an hitherto unknown structure type. The crystal structure of LiCrII4(PO4)3 is isotypic to that of NaCdII4(PO4)3 and related to that of the mineral silicocarnotite Ca5(PO4)2(SiO4). Significant disorder between Li+ and Cr2+ is observed for both crystal structures. The oxidation states assigned to chromium in these two phosphates are in agreement with UV/vis/NIR absorption spectra and magnetic susceptibility data recorded for both compounds. Instead of “LiCrIIPO4” mixtures of LiCrII4(PO4)3, Li5CrII2CrIII(PO4)4, Cr2O3, and CrP are observed at equilibrium. Instead of “Li2CrIIP2O7” four-phase mixtures consisting of Li9CrIII3(P2O7)3(PO4)2, Li3CrIII2(PO4)3, LiCrP2O7, and CrP were obtained.

Soft X-ray laser using pumping of 3P and 4P levels of He-like and H-like ions

DOEpatents

Hagelstein, P.L.

1987-04-21

X-ray laser method and apparatus are disclosed for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4-50 cm[sup [minus]1]. 8 figs.

Investigation of Reaction Mechanism on the Lime-Free Roasting of Chromium-Containing Slag

NASA Astrophysics Data System (ADS)

Yu, Kai-ping; Zhang, Hong-ling; Chen, Bo; Xu, Hong-bin; Zhang, Yi

2015-12-01

The lime-free roasting process of trivalent chromium-containing slag was investigated. The effect of Fe and liquid phase on the conversion reaction of chromium was discussed. The oxidation of trivalent chromium depends greatly on the diffusion of Na+ and O2. Both the raw material Na2CO3 and the intermediate product NaFeO2 serve as the carriers of Na+. The Na+ diffusion is improved by the binary liquid phase of Na2CrO4-Na2CO3, whereas excess liquid phase results in a low conversion rate of chromium by hindering the diffusion of oxygen towards the reaction interface. With the increasing of liquid volume, the controlled step of chromium oxidation changes from Na+ diffusion to oxygen diffusion. The mechanism study showed that the volume of liquid phase increased while raising the reaction temperature or prolonging the reaction time. Based on the role of both liquid phase and Fe, the oxidation process of chromium was summarized as a three-stage model: the Na+ diffusion-controlled stage, the O2 diffusion-controlled stage, and the oxidation reaction halted stage.

Materials Data on NaCr2P2O9 (SG:62) by Materials Project

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

Kristin Persson

2017-07-17

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions.

PubMed

Kwak, Hyo Won; Shin, Munju; Yun, Haesung; Lee, Ki Hoon

2016-09-02

In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A 1 M lithium chloride (LiCl)/dimethyl sulfoxide (DMSO) solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI) adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI) occurred on the heterogeneous surface. Cr(VI) adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI) ions were recovered from the Cr(VI) adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI) ions in industrial wastewater.

Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions

PubMed Central

Kwak, Hyo Won; Shin, Munju; Yun, Haesung; Lee, Ki Hoon

2016-01-01

In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A 1 M lithium chloride (LiCl)/dimethyl sulfoxide (DMSO) solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI) adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI) occurred on the heterogeneous surface. Cr(VI) adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI) ions were recovered from the Cr(VI) adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI) ions in industrial wastewater. PMID:27598142

Optical and structural investigation on sodium borosilicate glasses doped with Cr2O3

NASA Astrophysics Data System (ADS)

Ebrahimi, E.; Rezvani, M.

2018-02-01

In this work, Sodium borosilicate glasses with chemical composition of 60% SiO2-20% B2O3-20%Na2O doped with different contents of Cr2O3 were prepared by melting-quenching method. Physical, structural and optical properties of glasses were investigated by studying density and molar volume, Fourier Transform Infrared (FT-IR) Spectra and UV-visible absorption spectroscopy. The results showed an increase in density of glasses with the increase of Cr2O3 that can be due to addition of oxide with high molar mass. The optical absorption spectra of un-doped glass reveals UV absorption due to trace iron impurities with no visible band however Cr2O3 doped glasses shows absorption in visible range that are characteristic. Increasing of Cr3 + ions in the glassy microstructure of samples provides a semiconducting character to Sodium borosilicate glass by reducing the direct and indirect optical band gaps of glass samples from 3.79 to 2.59 (ev) and 3.36 to 2.09 (ev), respectively. These changes could be attributed to the role of Cr3 + ions as the network former which asserts improvement of semiconducting behavior in presence of Cr2O3.

Chromium recovery from exhausted baths generated in plating processes and its reuse in the tanning industry.

PubMed

Torras, Josep; Buj, Irene; Rovira, Miquel; de Pablo, Joan

2012-03-30

Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution. Copyright © 2012 Elsevier B.V. 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.

Optical and structural investigation on sodium borosilicate glasses doped with Cr2O3.

PubMed

Ebrahimi, E; Rezvani, M

2018-02-05

In this work, Sodium borosilicate glasses with chemical composition of 60% SiO 2 -20% B 2 O 3 -20%Na 2 O doped with different contents of Cr 2 O 3 were prepared by melting-quenching method. Physical, structural and optical properties of glasses were investigated by studying density and molar volume, Fourier Transform Infrared (FT-IR) Spectra and UV-visible absorption spectroscopy. The results showed an increase in density of glasses with the increase of Cr 2 O 3 that can be due to addition of oxide with high molar mass. The optical absorption spectra of un-doped glass reveals UV absorption due to trace iron impurities with no visible band however Cr 2 O 3 doped glasses shows absorption in visible range that are characteristic. Increasing of Cr 3+ ions in the glassy microstructure of samples provides a semiconducting character to Sodium borosilicate glass by reducing the direct and indirect optical band gaps of glass samples from 3.79 to 2.59 (ev) and 3.36 to 2.09 (ev), respectively. These changes could be attributed to the role of Cr 3+ ions as the network former which asserts improvement of semiconducting behavior in presence of Cr 2 O 3 . Copyright © 2017. Published by Elsevier B.V.

Major and trace element concentrations in samples from 72275 and 72255. [chemical composition of lunar rocks

NASA Technical Reports Server (NTRS)

Haskin, L. A.; Blanchard, D. P.; Korotev, R.; Jacobs, J. W.; Brannon, J. A.; Herrmann, A. G.

1974-01-01

Analytical data have been obtained for Co, Sc, Hf, Zn, Cr, Ga, Rb, Cs, Ni, major elements, and rare earth elements in eight samples from boulder 1. The data for trace elements were obtained by radiochemical neutron activation analysis. Major elements, except Na and Mn, were obtained by atomic absorption spectral photometry. Values for Na and Mn were obtained by neutron activation analysis of the same powder that was later dissolved to provide the atomic absorption analyses.

Padrões de refluxo nas veias safenas em homens com insuficiência venosa crônica

PubMed Central

Engelhorn, Carlos Alberto; Coral, Francisco Eduardo; Soares, Isabela Chaves Monteiro; Corrêa, Gabriel Fernando de Araújo; Ogeda, Jaqueline Pozzolo; Hara, Larissa Yuri; Murasse, Luisa Saemi

2016-01-01

Resumo Contexto A insuficiência venosa crônica (IVCr) é frequente e predomina nas mulheres, mas ainda há poucas informações sobre o refluxo nas veias safenas na população masculina. Objetivos Identificar os diferentes padrões de refluxo nas veias safenas magnas (VSMs) e parvas (VSPs) em homens, correlacionando esses dados com a apresentação clínica conforme a classificação Clínica, Etiológica, Anatômica e Fisiopatológica (CEAP). Métodos Foram avaliados 369 membros inferiores de 207 homens pela ultrassonografia vascular (UV) com diagnóstico clínico de IVCr primária. As variáveis analisadas foram a classificação CEAP, o padrão de refluxo nas VSMs e VSPs e a correlação entre os dois. Resultados Nos 369 membros avaliados, 72,9% das VSMs apresentaram refluxo com predominância do padrão segmentar (33,8%). Nas VSPs, 16% dos membros inferiores analisados apresentaram refluxo, sendo o mais frequente o padrão distal (33,9%). Dos membros classificados como C4, C5 e C6, 100% apresentaram refluxo na VSM com predominância do refluxo proximal (25,64%), e 38,46% apresentaram refluxo na VSP com equivalência entre os padrões distal e proximal (33,3%). Refluxo na junção safeno-femoral (JSF) foi detectado em 7,1% dos membros nas classes C0 e C1, 35,6% nas classes C2 e C3, e 64,1% nas classes C4 a C6. Conclusões O padrão de refluxo segmentar é predominante na VSM, e o padrão de refluxo distal é predominante na VSP. A ocorrência de refluxo na JSF é maior em pacientes com IVCr mais avançada. PMID:29930603

Understanding effect of 3.5 wt.% NaCl on the corrosion of Al0.1CoCrFeNi high-entropy alloy

NASA Astrophysics Data System (ADS)

Kumar, N.; Fusco, M.; Komarasamy, M.; Mishra, R. S.; Bourham, M.; Murty, K. L.

2017-11-01

High entropy alloys are a new class of metallic materials with potential for use in a wide variety of applications including their use in corrosive environment. The present study focused on the corrosion behavior of a single-phase, face-centered cubic high entropy alloy (HEA) Al0.1CoCrFeNi in as-cast condition, and the results are compared with the corrosion behavior of the SS304. The microstructural characterization of the alloys in as-received condition was carried out using optical microscopy, electron backscattered diffraction, energy dispersive spectroscopy, and X-ray diffraction. Corrosion behavior was studied using potentiodynamic polarization test in a 3.5 wt% NaCl solution and electrochemical impedance spectroscopy at room temperature. It was observed that the general corrosion resistance of the HEA was better than that of SS304. Pitting potential of the HEA was found to be superior to that of the SS304. Corrosion pits size was slightly smaller in SS304 than that in the HEA. 3D imaging determined that the pit depths were of the same order in both cases. Overall, the HEA Al0.1CoCrFeNi demonstrated a better resistance to general and pitting corrosion.

The influence of aliovalent impurities on the oxidation kinetics of nickel at high temperatures

NASA Astrophysics Data System (ADS)

Mrowec, S.; Grzesik, Z.; Rajchel, B.; Gil, A.; Dabek, J.

2005-01-01

The influence of chromium and sodium on the nickel oxidation kinetics has been studied as a function of temperature (1373-1673 K) and oxygen activity (10-105 Pa O2), using microthermogravimetric techniques. It has been shown that the oxidation of Ni-Cr and Ni-Na alloys, like that of pure nickel, follows strictly the parabolic rate law being thus diffusion controlled. In agreement with the defect model of Ni1-yO, it has been found that the oxidation rate of the Ni-Cr alloy is higher than that of pure nickel, the reaction rate is pressure independent and the activation energy of this process is lower. This implies that the concentration of double ionized cation vacancies in a Ni1-yO-Cr2O3 solid solution is fixed on a constant level by trivalent chromium ions, substitutionally incorporated into the cation sublattice of this oxide. In the case of the Ni-Na alloy, on the other hand, the oxidation rate is lower than that of pure nickel, the activation energy is higher and the oxidation rate increases more rapidly with oxygen pressure. These results can again be explained in terms of the doping effect, by assuming that univalent sodium ions dissolve substitutionally in the cation sublattice of nickel oxide.

Corrosion of Alloy 690 process pot by sulfate containing high level radioactive waste at feed stage

NASA Astrophysics Data System (ADS)

Sengupta, P.; Soudamini, N.; Kaushik, C. P.; Jagannath; Mishra, R. K.; Kale, G. B.; Raj, K.; Das, D.; Sharma, B. P.

2008-02-01

Prolonged exposure of Alloy 690 process pot to sulfate containing high level radioactive waste leads to (a) depletion of Cr from the alloy, (b) intergranular attack and (c) building up of Cr 2O 3-Ni 2O 3-Fe 2O 3 mixed oxide surface layer containing Na and Cs sulfate precipitates. Time dependence of material loss from Alloy 690 is found to follow a linear relationship of the type Δ w (material loss) = -7.05 + 0.05 t. Corrosion rate calculated for 2400 h exposure is 3.66 mpy. Cr and Ni leach rates obtained for the same sample are 1.61 g m -2 d -1 and 2.52 g m -2 d -1, respectively. Ni leach rates followed a linear time dependence relationship of the type dNL Ni/d t (leach rate) = -0.09 + 0.027 t, whereas Cr leach rates obeyed a non-linear relationship of the type dNL Cr/d t (leach rate) = 0.241 + 0.027 t - 1.33 × 10 -4t1/2.

Corrosion behavior of high-strength spring steel for high-speed railway

NASA Astrophysics Data System (ADS)

Niu, Gang; Chen, Yin-li; Wu, Hui-bin; Wang, Xuan; Tang, Di

2018-05-01

The corrosion resistance and evolution of corrosion products in medium-carbon high-strength spring steels were investigated in a neutral salt spray (5wt% NaCl solution). A formation model of γ-FeOOH and a transformation model describing the conversion of γ-FeOOH to α-FeOOH were constructed. The results indicated that, at the initial corrosion stage, the corrosion resistance was gradually improved with the addition of Cr; however, with the addition of alloying element V, the corrosion resistance decreased. These results were attributed mainly to the initial corrosion stage being closely related to the matrix microstructure parameters such as grain-boundary character and dislocation density. After the rust layer was formed at a later corrosion stage, the corrosion resistance was reinforced with the addition of Cr and V because Cr strongly influenced the composition, structure, and morphology of the corrosion products. The results presented herein show that Cr was conducive to the transformation of γ-FeOOH into α-FeOOH. Moreover, V and Cr exhibited obvious synergy and were enriched in the inner layer of the corrosion products.

In-situ Raman and X-ray photoelectron spectroscopic studies on the pitting corrosion of modified 9Cr-1Mo steel in neutral chloride solution

NASA Astrophysics Data System (ADS)

Ramya, S.; Nanda Gopala Krishna, D.; Mudali, U. Kamachi

2018-01-01

In-situ Raman and X-ray photoelectron spectroscopic studies were performed for the identification of native and corroded surface oxide layers of modified 9Cr-1Mo steel. The Raman data obtained for native oxide layer of modified 9Cr-1Mo steel revealed that it was mainly composed of oxides of Fe and Cr. The presence of alloying element Mo was found to be less significant in the native oxide film. The oxides of Cr were dominant at the surface and were found to be decreasing closer to metal/oxide layer interface. The changes in the chemical composition of the native films upon in-situ pitting during potentiostatic polarization experiment were characterized by in-situ Raman analysis. The corrosion products of potentiostatically polarized modified 9Cr-1Mo steel was composed of dominant Fe (III) phases viz., γ- Fe2O3, α and γ - FeOOH along with the oxides of chromium. The results from Raman analysis were corroborated with the XPS experiments on as received and pitted samples of modified 9Cr-1Mo steel specimens. It was observed that the oxides of Cr and Mo contributed for the stability of the surface layer by forming Cr2O3 and MoO3. Also, the study attempted to find out the intermediate corrosion products inside the metastable pits to account for the pseudo passive behavior of modified 9Cr-1Mo steel in 0.1 M NaCl solution.

An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration.

PubMed

Liu, Jingyong; Fu, Jiewen; Ning, Xun'an; Sun, Shuiyu; Wang, Yujie; Xie, Wuming; Huang, Shaosong; Zhong, Sheng

2015-09-01

The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4. Copyright © 2015. Published by Elsevier B.V.

Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Chen-Tung; Kandasamy, Selvaraj

2008-05-01

Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

High purity polyimide analysis by solid sampling graphite furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Santos, Rafael F.; Carvalho, Gabriel S.; Duarte, Fabio A.; Bolzan, Rodrigo C.; Flores, Erico M. M.

2017-03-01

In this work, Cr, Cu, Mn, Na and Ni were determined in high purity polyimides (99.5%) by solid sampling graphite furnace atomic absorption spectrometry (SS-GFAAS) using Zeeman effect background correction system with variable magnetic field, making possible the simultaneous measurement at high or low sensitivity. The following analytical parameters were evaluated: pyrolysis and atomization temperatures, feasibility of calibration with aqueous solution, linear calibration range, sample mass range and the use of chemical modifier. Calibration with aqueous standard solutions was feasible for all analytes. No under or overestimated results were observed and up to 10 mg sample could be introduced on the platform for the determination of Cr, Cu, Mn, Na and Ni. The relative standard deviation ranged from 3 to 20%. The limits of detection (LODs) achieved using the high sensitivity mode were as low as 7.0, 2.5, 1.7, 17 and 0.12 ng g- 1 for Cr, Cu, Mn, Na and Ni, respectively. No addition of chemical modifier was necessary, except for Mn determination where Pd was required. The accuracy was evaluated by analyte spike and by comparison of the results with those obtained by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry after microwave-assisted digestion in a single reaction chamber system and also by neutron activation analysis. No difference among the results obtained by SS-GFAAS and those obtained by alternative analytical methods using independent techniques. SS-GFAAS method showed some advantages, such as the determination of metallic contaminants in high purity polyimides with practically no sample preparation, very low LODs, calibration with aqueous standards and determination in a wide range of concentration.

Evaluated the Twenty-Six Elements in the Pectoral Muscle of As-Treated Chicken by Inductively Coupled Plasma Mass Spectrometry.

PubMed

Sun, Bonan; Xing, Mingwei

2016-02-01

This study assessed the impacts of dietary arsenic trioxide on the contents of 26 elements in the pectoral muscle of chicken. A total of 100 Hy-line laying cocks were randomly divided into two groups (n = 50), including an As-treated group (basic diet supplemented with arsenic trioxide at 30 mg/kg) and a control group (basal diet). The feeding experiment lasted for 90 days and the experimental animals were given free access to feed and drinking water. The elements lithium (Li), boron (B), natrum (Na), magnesium (Mg), aluminium (AI), silicium (Si), kalium (K), calcium (Ca), vanadium (V), chromium (Cr), manganese (Mn), ferrum (Fe), cobalt (Co.), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), stannum (Sn), stibium (Sb), barium (Ba), hydrargyrum (Hg), thallium (Tl) and plumbum (Pb) in the pectoral muscles were determined using inductively coupled plasma mass spectrometry (ICP-MS). The resulted data indicated that Li, Na, AI, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ba, Tl and Pb were significantly increased (P < 0.05) in chicken exposed to As2O3 compared to control chicken, while Mg, Si, K, As and Cd decreased significantly (P < 0.05). These results suggest that ICP-MS determination of elements in chicken tissues enables a rapid analysis with good precision and accuracy. Supplementation of high levels of As affected levels of 20 elements (Li, Na, AI, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ba, Tl, Pb, Mg, Si, K, As and Cd) in the pectoral muscles of chicken. Thus, it is needful to monitor the concentration of toxic metal (As) in chicken for human health.

Modacrylic anion-exchange fibers for Cr(VI) removal from chromium-plating rinse water in batch and flow-through column experiments.

PubMed

Lee, Seung-Chan; Kang, Jin-Kyu; Sim, Eun-Hye; Choi, Nag-Choul; Kim, Song-Bae

2017-11-10

The aim of this study was to investigate Cr(VI) removal from chromium-plating rinse water using modacrylic anion-exchange fibers (KaracaronTM KC31). Batch experiments were performed with synthetic Cr(VI) solutions to characterize the KC31 fibers in Cr(VI) removal. Cr(VI) removal by the fibers was affected by solution pH; the Cr(VI) removal capacity was the highest at pH 2 and decreased gradually with a pH increase from 2 to 12. In regeneration and reuse experiments, the Cr(VI) removal capacity remained above 37.0 mg g -1 over five adsorption-desorption cycles, demonstrating that the fibers could be successfully regenerated with NaCl solution and reused. The maximum Cr(VI) removal capacity was determined to be 250.3 mg g -1 from the Langmuir model. In Fourier-transform infrared spectra, a Cr = O peak newly appeared at 897 cm -1 after Cr(VI) removal, whereas a Cr-O peak was detected at 772 cm -1 due to the association of Cr(VI) ions with ion-exchange sites. X-ray photoelectron spectroscopy analyses demonstrated that Cr(VI) was partially reduced to Cr(III) after the ion exchange on the surfaces of the fibers. Batch experiments with chromium-plating rinse water (Cr(VI) concentration = 1178.8 mg L -1 ) showed that the fibers had a Cr(VI) removal capacity of 28.1-186.4 mg g -1 under the given conditions (fiber dose = 1-10 g L -1 ). Column experiments (column length = 10 cm, inner diameter = 2.5 cm) were conducted to examine Cr(VI) removal from chromium-plating rinse water by the fibers under flow-through column conditions. The Cr(VI) removal capacities for the fibers at flow rates of 0.5 and 1.0 mL min -1 were 214.8 and 171.5 mg g -1 , respectively. This study demonstrates that KC31 fibers are effective in the removal of Cr(VI) ions from chromium-plating rinse water.

Lenalidomide-induced myelosuppression is associated with renal dysfunction: adverse events evaluation of treatment-naïve patients undergoing front-line lenalidomide and dexamethasone therapy.

PubMed

Niesvizky, Ruben; Naib, Tara; Christos, Paul J; Jayabalan, David; Furst, Jessica R; Jalbrzikowski, Jessica; Zafar, Faiza; Mark, Tomer; Lent, Richard; Pearse, Roger N; Ely, Scott; Leonard, John P; Mazumdar, Madhu; Chen-Kiang, Selina; Coleman, Morton

2007-09-01

Data on 72 patients receiving lenalidomide/dexamethasone for multiple myeloma (MM) was used to determine the factors that are associated with lenalidomide-induced myelosuppression. Eight of 14 patients with grade > or =3 myelosuppression had baseline creatinine clearance (CrCl) < or =0.67 ml/s. Kaplan-Meier analysis by log-rank test demonstrated a significant association (P < 0.0001) between renal insufficiency and time to myelosuppression (hazard ratio = 8.4; 95% confidence interval 2.9-24.7, P = 0.0001). Therefore, CrCl is inversely associated with significant myelosuppression. Caution should be exercised when lenalidomide therapy is commenced and CrCl should be incorporated as a determinant of the initial dosing of lenalidomide in MM patients.

Competitive adsorption of boric acid and chromate onto alumina in aqueous solutions.

PubMed

Demetriou, A; Pashalidis, I

2014-01-01

The competitive adsorption of boric acid and chromate from aqueous solutions by alumina has been investigated by spectrophotometry at pH 8, ionic strength = 0.0, 0.1 and 1.0 M NaClO4, T = 22 ± 3 °C and under normal atmospheric conditions. The experimental data show that addition of excess boric acid in the system leads to the increase of Cr(VI) concentration in solution, indicating the replacement of adsorbed chromate by boron on the alumina surface. Data evaluation results in the determination of the competition reaction constant and the formation constant of the Cr(VI) surface complexes, which are logKCr(VI)-B(III) = -3.5 ± 0.2 and logβ*Cr = 7.6 ± 0.3, respectively.

Corrosion fatigue crack growth behavior of titanium alloys in aqueous solutions

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

Shipilov, S.A.

1998-01-01

The corrosion fatigue crack growth (FCG) behavior, the effect of applied potential on corrosion FCG rates, and the fracture surfaces of VT20 (near-{alpha}) and TS6 (near-{beta}) titanium alloys were studied. Environments were aqueous solutions of sodium chloride (NaCl), sodium hydroxide (NaOH), potassium hydroxide (KOH), ferric chloride (FeCl{sub 3}), and chromic acid (H{sub 2}CrO{sub 4}) with and without NaCl. Depending upon solution composition, corrosion FCG rates were found to be higher or lower than those in air. Cathodic polarization retarded the corrosion FCG, while anodic polarization accelerated insignificantly or almost did not influence it in most of the solutions investigated. However,more » cathodic polarization accelerated corrosion FCG in 0.6 M FeCl{sub 3} and 0.5 M to 2 M H{sub 2}CrO{sub 4} + 0.01 M to 0.1 M NaCl solutions by a dozen times when the maximum stress intensity (K{sub max}) exceeded certain critical values. When K{sub max} was lower than the critical values, the same cathodic polarization (with all other /conditions being equal) retarded corrosion FCG. Results suggested the accelerated crack growth at cathodic potentials resulted from hydrogen-induced cracking (HIC). Therefore, critical values of K{sub max}, as well as the stress intensity range ({Delta}K) were regarded as corresponding to the beginning of corrosion FCG according to a HIC mechanism and designated as K{sub HIC} and {Delta}K{sub HIC}.« less

Material and structural characterization of alkali activated low-calcium brown coal fly ash.

PubMed

Skvára, Frantisek; Kopecký, Lubomír; Smilauer, Vít; Bittnar, Zdenek

2009-09-15

The waste low-calcium Czech brown coal fly ash represents a considerable environmental burden due to the quantities produced and the potentially high content of leachable heavy metals. The heterogeneous microstucture of the geopolymer M(n) [-(Si-O)(z)-Al-O](n).wH(2)O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ((29)Si, (27)Al, (23)Na), ESEM, EDS, and EBSD. The leaching of heavy metals and the evolution of compressive strength were also monitored. The analysis of raw fly ash identified a number of different morphologies, unequal distribution of elements, Fe-rich rim, high internal porosity, and minor crystalline phases of mullite and quartz. Microcalorimetry revealed exothermic reactions with dependence on the activator alkalinity. The activation energy of the geopolymerization process was determined as 86.2kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the (29)Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO(4) tetrahedra. The (23)Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H(2)O)(n) rather than Na(+), thus causing efflorescence in a moisture-gradient environment. As and Cr(6+) are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn(2+), Cu(2+), Cd(2+), and Cr(3+) are reported.

Compositional analysis and pollution impact assessment: A case study in the Gulfs of Naples and Salerno

NASA Astrophysics Data System (ADS)

Menghan, Wang; Stefano, Albanese; Annamaria, Lima; Claudia, Cannatelli; Antonio, Cosenza; Wanjun, Lu; Marco, Sacchi; Angela, Doherty; Benedetto, De Vivo

2015-07-01

This paper presents the results of an environmental geochemical investigation of the Gulfs of Naples and Salerno, near the Campania plain (Southern Italy). Surface marine sediment samples were collected during three field campaigns: 96 from the Gulfs of Naples and Salerno (NaSa); 123 from the Bagnoli site coastal area (BaSi); and 11 from the ports around the Gulf of Naples (PoNa). Elemental concentrations were determined and their interpolated distribution maps were compiled. Three geochemical sources (or processes) were determined associating elemental distribution with the results obtained from a R-mode factor analysis: 1) geogenic, 2) water kinetics and 3) anthropogenic. The results are presented as raw data single element distributions of eight potential toxic elements (PTEs) (As, Cd, Cr, Cu, Hg, Pb, Ni and Zn) in the forms of raw data and additive log-ratio transformed data. The latter showed advantages in revealing the actual distribution patterns. Geochemical background reference values of PTEs were determined from the median value of local background reference values. Based on these values, pollution impact analysis was carried out to both BaSi and PoNa samples, indicating most of BaSi and PoNa sediments were affected by moderate to strong Pb, Zn, Cd and Hg pollution. An ecological risk assessment was subsequently carried out on the entire database, pointing a toxic risk ranking in the order Pb > As > Ni > Cd > Hg > Cr.

Phosphate-based glasses: Prediction of acoustical properties

NASA Astrophysics Data System (ADS)

El-Moneim, Amin Abd

2016-04-01

In this work, a comprehensive study has been carried out to predict the composition dependence of bulk modulus and ultrasonic attenuation coefficient in the phosphate-based glass systems PbO-P2O5, Li2O-TeO2-B2O3-P2O5, TiO2-Na2O-CaO-P2O5 and Cr2O3-doped Na2O-ZnO-P2O5 at room temperature. The prediction is based on (i) Makishima-Mackenzie theory, which correlates the bulk modulus with packing density and dissociation energy per unit volume, and (ii) Our recently presented semi-empirical formulas, which correlate the ultrasonic attenuation coefficient with the oxygen density, mean atomic ring size, first-order stretching force constant and experimental bulk modulus. Results revealed that our recently presented semi-empirical formulas can be applied successfully to predict changes of ultrasonic attenuation coefficient in binary PbO-P2O5 glasses at 10 MHz frequency and in quaternary Li2O-TeO2-B2O3-P2O5, TiO2-Na2O-CaO-P2O5 and Cr2O3-Na2O-ZnO-P2O5 glasses at 5 MHz frequency. Also, Makishima-Mackenzie theory appears to be valid for the studied glasses if the effect of the basic structural units that present in the glass network is taken into account.

The non-serpentine phases in serpentinites from the Braszowice-Brzeźnica Massif (SW Poland) as traces of magmatic processes within oceanic mantle

NASA Astrophysics Data System (ADS)

Wojtulek, Piotr; Puziewicz, Jacek; Ntaflos, Theodoros

2016-04-01

The Braszowice-Brzeźnica Massif - BBM (SW Poland) is a part of the Variscan Central-Sudetic Ophiolite. It is located at the southern termination of the Niemcza Shear Zone and consists of gabbros and serpentinites. The ultramafic rocks occurring in the BBM are (from E to W) serpentinites with abundant relics of olivine and tremolite, lizardite-chrysotile serpentinites and antigorite serpentinites. Clinopyroxene, olivine and zoned chromite grains were found in the central part of the BBM (Mnich Hill) within antigoritic serpentinites. The non-serpentine phases occur in the following microstructures: (1) olivine-chromite aggregates: olivine (Fo = 90.0-91.0) contains 0.35-0.44 wt.% NiO, elongated or amaeboidal chromite I (Cr# = 0.49-0.50, TiO2 = 0.14-0.15 wt.%) is rimmed by chromite II (Cr# = 0.98, TiO2 = 0.01 wt.%); (2) coarse and dismembered diopside grains (Cpx I, Mg# = 0.91-0.92) containing 0.70-0.80 wt.% TiO2, 3.0-4.0 wt.% Al2O3, 1.0-1.4 Cr2O3 and 0.3-0.5 wt.% Na2O; Cpx I is enriched in REE relative to primitive mantle, the REE pattern reveals HREE enrichment relative to LREE and negative Eu anomaly; (3) olivine-clinopyroxene aggregates: olivine (Fo = 90.4-91.3) contains 0.27-0.35 wt.% NiO, anhedral, often elongated clinopyroxene (Cpx II, Mg# = 0.91-0.92) has <0.1 wt.% TiO2, 3.00-4.00 wt.% Al2O3, 1.00-1.40 Cr2O3 and <0.20 wt.% Na2O, (4) magnetite-bearing olivine grains, locally in aggregates with minute clinopyroxene ones; olivine has variable Fo (86.0-96.0) and NiO concentration (0.02-0.55 wt.%), clinopyroxene (Cpx III, Mg# = 0.93-0.97) contains <0.40 wt.% Al2O3 and <0.20 Cr2O3. Cpx III rims also locally Cpx II. The non-serpentine phases from the BBM massif have various compositions and mode of occurrence, thus they record various crystallization events. Composition of chromite I is similar to primary chromite grains occurring in oceanic peridotites of the Romanche and Kurchatov F.Z. (Dick and Bullen, 1984), thus the olivine-chromite aggregates represent probably primary mantle phases. Cpx I contains similar amount of the Al2O3, Cr2O3 and Na2O to primary diopsides described from the Marie Celeste FZ and Indomed FZ (Johnson et al., 1990). REE pattern of the Cpx I suggests depletion in mobile trace elements due to melt extraction. Cpx II has Al2O3, Cr2O3 and TiO2 contents similar to those of diopside originated from the melt-percolation reactions, olivine coexisting with Cpx II crystallized probably in the same event. The Cpx III has Al, Cr and Na contents typical for secondary, metamorphic clinopyroxene. Magnetite-bearing olivine is similar to olivine crystallized at expense of serpentine+magnetite precursors, thus is has secondary, metamorphic origin. This abstract was prepared as a part of the project of the National Science Centre of Poland ("Evolution of serpentinic members of the Lower Silesia ophiolites", DEC-2012/07/N/ST10/03934). References Dick, H.J.B., Bullen, T., 1984. Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contributions to Mineralogy and Petrology 86, 54-76. Johnson K.T.M., Dick H.J.B., Shimizu N., 1990. Melting in the Oceanic Upper Mantle - an ion microprobe study of Diopsides in Abyssal Peridotites. Journal of Geophysical Research 95, 2661-2678.

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

Parrado, G., E-mail: gparrado@sgc.gov.co; Cañón, Y.; Peña, M., E-mail: mlpena@sgc.gov.co

The Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey has developed a technique for multi-elemental analysis of soil and plant matrices, based on Instrumental Neutron Activation Analysis (INAA) using the comparator method. In order to evaluate the analytical capabilities of the technique, the laboratory has been participating in inter-comparison tests organized by Wepal (Wageningen Evaluating Programs for Analytical Laboratories). In this work, the experimental procedure and results for the multi-elemental analysis of four soil and four plant samples during participation in the first round on 2015 of Wepal proficiency test are presented. Only elements with radioactive isotopes withmore » medium and long half-lives have been evaluated, 15 elements for soils (As, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Th, U and Zn) and 7 elements for plants (Br, Co, Cr, Fe, K, Na and Zn). The performance assessment by Wepal based on Z-score distributions showed that most results obtained |Z-scores| ≤ 3.« 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).

Effect of Sulfur and Chlorine on Fireside Corrosion Behavior of Inconel 740 H Superalloy

NASA Astrophysics Data System (ADS)

Jin-tao, Lu; Yan, Li; Zhen, Yang; Jin-yang, Huang; Ming, Zhu; Gu, Y.

2018-03-01

Fireside corrosion behavior of Inconel 740H superalloy was studied at 750 °C in simulated coal ash/flue gas environments by means of XRD, SEM and EDS. The results indicated that the corrosion behavior was strongly related to the SO2 levels and was significantly affected by NaCl additions. In presence of the atmospheres with 0.1 % SO2, the alloy exhibited the highest corrosion resistance due to formation of a stable and dense Cr2O3 film. In presence of the atmosphere with 1.5 % SO2, however, a non-coherent and porous Cr2O3 film was formed. The thickness of film and internal sulfides were substantially increased. The NaCl additions significantly accelerated the corrosion process. A non-protective outer oxide film was formed, composed by multiple layers with serious inner sulfide and spallation. The depths of internal oxidizing and sulfuration zones were significantly increased. The mechanism of ash corrosion formation was also discussed.

Trace elements distribution in hawksbill turtle (Eretmochelys imbricata) and green turtle (Chelonia mydas) tissues on the northern coast of Bahia, Brazil.

PubMed

de Macêdo, Gustavo R; Tarantino, Taiana B; Barbosa, Isa S; Pires, Thaís T; Rostan, Gonzalo; Goldberg, Daphne W; Pinto, Luis Fernando B; Korn, Maria Graças A; Franke, Carlos Roberto

2015-05-15

Concentrations of elements (As, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn) were determined in liver, kidneys and bones of Eretmochelys imbricata and Chelonia mydas specimens found stranded along the northern coast of Bahia, Brazil. Results showed that the concentrations of Cd, Cu, Ni and Zn in the liver and kidneys of juvenile C. mydas were the highest found in Brazil. We also observed a significant difference (p<0.05) on the bioaccumulation of trace elements between the two species: Al, Co, Mo, Na and Se in the liver; Al, Cr, Cu, K, Mo, Ni, Pb, Sr and V in the kidneys; and Al, Ba, Ca, Cd, Mn, Ni, Pb, Se, Sr and V in the bones. This study represents the first report on the distribution and concentration of trace elements in E. imbricata in the Brazilian coast. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improvement of analytical capabilities of neutron activation analysis laboratory at the Colombian Geological Survey

NASA Astrophysics Data System (ADS)

Parrado, G.; Cañón, Y.; Peña, M.; Sierra, O.; Porras, A.; Alonso, D.; Herrera, D. C.; Orozco, J.

2016-07-01

The Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey has developed a technique for multi-elemental analysis of soil and plant matrices, based on Instrumental Neutron Activation Analysis (INAA) using the comparator method. In order to evaluate the analytical capabilities of the technique, the laboratory has been participating in inter-comparison tests organized by Wepal (Wageningen Evaluating Programs for Analytical Laboratories). In this work, the experimental procedure and results for the multi-elemental analysis of four soil and four plant samples during participation in the first round on 2015 of Wepal proficiency test are presented. Only elements with radioactive isotopes with medium and long half-lives have been evaluated, 15 elements for soils (As, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Th, U and Zn) and 7 elements for plants (Br, Co, Cr, Fe, K, Na and Zn). The performance assessment by Wepal based on Z-score distributions showed that most results obtained |Z-scores| ≤ 3.

Inguinodynia in patients submitted to conventional inguinal hernioplasty.

PubMed

Dias, Bruno Garcia; Santos, Marcelo Protásio Dos; Chaves, Ana Barbara DE Jesus; Willis, Mariana; Gomes, Marcio Couto; Andrade, Fernandes Tavares; Melo, Valdinaldo Aragão DE; Santos, Paulo Vicente Dos

2017-01-01

to evaluate the incidence of chronic pain and its impact on the quality of life of patients submitted to inguinal hernioplasty using the Lichtenstein technique. this was a descriptive, cross-sectional study of patients operated under spinal anesthesia from February 2013 to February 2015 and who had already completed six postoperative months. We questioned patients about the presence of chronic inguinal pain and, if confirmed, invited them to a consultation in which we assessed the pain and its impact on quality of life. out of 158 patients submitted to the procedure, we identified 7.6% as having inguinodynia. Of these, there was an impact on the quality of life in 25%. the incidence of inguinodynia after hernioplasty with repercussion in quality of life was similar to the one of found in the world literature. avaliar a incidência de dor crônica e o seu impacto na qualidade de vida de pacientes submetidos à hernioplastia inguinal pela técnica de Lichtenstein. trata-se de estudo transversal descritivo, de pacientes operados de hérnia inguinal pela técnica de Lichtenstein sob anestesia raquidiana, no período de fevereiro de 2013 a fevereiro de 2015, e que já haviam completado seis meses de pós-operatório. Os pacientes foram questionados sobre a presença de dor inguinal crônica e, caso confirmada, convidados a uma consulta na qual foi feita análise da qualidade da dor e seu impacto na qualidade de vida. do total de 158 pacientes submetidos ao procedimento, 7,6% foram identificados como portadores de inguinodinia. Destes, houve impacto na qualidade de vida em 25%. observou-se incidência de inguinodinia pós-hernioplastia com repercussão na qualidade de vida semelhante à literatura mundial.

Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals.

PubMed

Lin, Hao; Xu, Dekang; Li, Anming; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

2016-06-16

A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb(3+), Tm(3+), Er(3+) and Li(+) doped β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+). Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb(3+)/Tm(3+)/Er(3+) doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm(3+):(3)F4 → (3)H6 to Er(3+):(4)I11/2 → (4)F9/2 and the cross-relaxation (CR) effect [Er(3+):(4)S3/2 + (4)I15/2 → (4)I9/2 + (4)I13/2] rather than the long-accepted mechanism [CR process among Er(3+):(4)F7/2 + (4)I11/2 → (4)F9/2 + (4)F9/2]. In addition, compared to the Li(+)-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+) with 15 mol% Li(+) doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies.

Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals

PubMed Central

Lin, Hao; Xu, Dekang; Li, Anming; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

2016-01-01

A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb3+, Tm3+, Er3+ and Li+ doped β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+. Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb3+/Tm3+/Er3+ doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm3+:3F4 → 3H6 to Er3+:4I11/2 → 4F9/2 and the cross-relaxation (CR) effect [Er3+:4S3/2 + 4I15/2 → 4I9/2 + 4I13/2] rather than the long-accepted mechanism [CR process among Er3+:4F7/2 + 4I11/2 → 4F9/2 + 4F9/2]. In addition, compared to the Li+-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+ with 15 mol% Li+ doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies. PMID:27306720

Accelerating CR-39 Track Detector Processing by Utilizing UV

NASA Astrophysics Data System (ADS)

Sparling, Jonathan; Padalino, Stephen; McLean, James; Sangster, Craig; Regan, Sean

2017-10-01

The use of CR-39 plastic as a Solid State Nuclear Track Detector is an effective technique for obtaining data in high energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched in NaOH at 80°C, producing micron-scale signal pits at the nuclear track sites. It has been shown that illuminating CR-39 with UV light prior to etching increases bulk and track etch rates, especially when combined with elevated temperature. Spectroscopic analysis for amorphous solids has helped identify which UV wavelengths are most effective at enhancing etch rates. Absorption peaks found in the near infrared range provide for efficient sample heating, and may allow targeting cooperative IR-UV chemistry. Avoiding UV induced noise can be achieved through variations in absorption depths with wavelength. Vacuum drying and water absorption tests allow measurement of the resulting variation of bulk etch rate with depth. Funded in part by the NSF and an Department of Energy Grant through the Lab of Laser Energetics.

A nutrition curriculum for families with high blood pressure.

PubMed

Farris, R P; Frank, G C; Webber, L S; Berenson, G S

1985-03-01

A nutrition curriculum for 48 students age eight-18 years with high blood pressure was implemented in Franklinton, La., as part of A Dietary/Exercise Alteration Program Trial (ADAPT), a model promoting reduced sodium (Na+) and energy intake and increased potassium (K+) intake. A teacher guide listed basic concepts, teacher and student activities, materials, behavioral outcomes, and evaluation for 12 lessons at three age levels. Games were used to present new information and increase student involvement. Taste-tests promoted attitude change regarding acceptable snacks. Decision-making and assertiveness topics facilitated independent food choices and coping with peers. Self-monitoring of intakes encouraged personal responsibility for eating behavior. Results of paired t-tests showed knowledge increased 8.7% in the spring (p less than 0.01), 4.9% in the summer (N.S.), and 7.3% in the fall (p less than 0.0001). No significant differences in increase in posttest scores by age were found. Comparisons of curriculum compliance with medication use and blood pressure change showed no relationship. A multiple regression analysis of sodium-creatinine (Na+/Cr) ratios on class attendance and posttest scores showed that children with the highest test scores had lower Na+/Cr ratios. This program increased information and skills for those motivated to change lifestyle to control obesity and blood pressure.

Influences of Cr/Ni equivalent ratios of filler wires on pitting corrosion and ductility-dip cracking of AISI 316L weld metals

NASA Astrophysics Data System (ADS)

Kim, Y. H.; Kim, D. G.; Sung, J. H.; Kim, I. S.; Ko, D. E.; Kang, N. H.; Hong, H. U.; Park, J. H.; Lee, H. W.

2011-02-01

To study the pitting corrosion of AISI 316L weld metals according to the chromium/nickel equivalent ratio (Creq/Nieq ratio), three filler wires were newly designed for the flux-cored arc welding process. The weld metal with delta-ferrite at less than 3 vol.%, was observed for ductility-dip cracking (DDC) in the reheated region after multi-pass welding. The tensile strength and yield strength increased with increasing Creq/Nieq ratio. The result of anodic polarization tests in a 0.1 M NaCl solution at the room temperature (25) for 45 min, revealed that the base metal and weld metals have a similar corrosion potential of -0.34 VSCE. The weld metal with the highest content of Cr had the highest pitting potential (0.39 VSCE) and the passivation range (0.64 VSCE) was higher than the base metal (0.21 VSCE and 0.46 VSCE, respectively). Adding 0.001 M Na2S to the 0.1M NaCl solution, the corrosion occurred more severely by H2S. The corrosion potentials of the base metal and three weld metals decreased to -1.0 VSCE. DDC caused the decrease of the pitting potential by inducing a locally intense corrosion attack around the crack openings.

Lake Ellen kimberlite, Michigan, U.S.A.

USGS Publications Warehouse

McGee, E.S.; Hearn, B.C.

1983-01-01

The recently discovered Lake Ellen kimberlite, in northern Michigan, indicates that bedrock sources of diamonds found in glacial deposits in the Great Lakes area could lie within the northern U.S. Magnetic surveys show a main kimberlite 200 m in diameter and an adjacent body 25 x 90 m(?). The kimberlite cuts Proterozoic volcanic rocks that overlie Archean basement, but is post-Ordovician in age based on abundant Ordovician(?) dolomite inclusions. Xenocrysts and megacrysts are ilmenite (abundant, 12.5-19% MgO), pyropealmandine and Cr-pyrope (up to 9.3% Cr2O3), Cr-diopside (up to 4.5% Cr2O3), olivine (Fo 91), enstatite and phlogopite. The kimberlite contains fragments of crustal schist and granulite, as well as disaggregated crystals and rare xenoliths of eclogites, garnet pyroxenites and garnet peridotites from a heterogeneous upper mantle. Eclogites, up to 3 cm size, show granoblastic equant or tabular textures and consist of jadeitic cpx (up to 8.4% Na20, 15.3% Al2O3), pyrope-almandine, ? rutile ? kyanite ? sanidine ? sulfide. Garnet pyroxenite contains pyrope--(0.44% Cr2O3) + cpx (0.85% Na2O, 0.53% Cr2O3) + Mg-Al spinel. Mineral compositions of rare composite xenocrysts of garnet + cpx are distinctively peridotitic, pyroxenitic or eclogitic. Calculated temperatures of equilibration are 920-1060 ?C for the eclogites and 820-910?C for the garnet pyroxenite using the Ellis-Green method. Five peridotite garnet-clinopyroxene composite xenocrysts have calculated temperatures of 980-1120?C using the Lindsley-Dixon 20 kb solvus. Spinel pyroxenite and clinopyroxene-orthopyroxene composites have lower calculated temperatures of 735?C and 820-900?C, respectively. Kyanite-bearing eclogites must have formed at pressures greater than 18-20 kb. Using the present shield geotherm with a heat flow value of 44mW/m 2 for the time of kimberlite emplacement, the eclogite temperatures imply pressures of 35-48 kb (105-140 km) and the garnet pyroxenite temperatures indicate pressures of 24-29 kb (75-90 km). Temperatures of two peridotitic garnet-cpx composite xenocrysts if on a shield geotherm, imply pressures within the diamond stability field.

Caustic stress corrosion tests for the LLTR

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

Indig, M.E.

1976-05-01

A series of tests have been performed in order to determine the effects of the caustic resulting from the Na/H/sub 2/O reaction on the materials used in the LLTR-MSG series of testing. Stainless steel, 2 /sup 1///sub 4/ Cr--1 Mo and carbon steel have been evaluated. Stress corrosion cracking susceptibility and general corrosion are reported. Over the range of temperature, caustic concentration and heating rate tested the stainless steel stressed to 90% of yield or above suffered cracking. Whereas, the 2-/sup 1///sub 4/ Cr--1 Mo and carbon steel were not cracked.

The effect of organic compounds in the oxidation kinetics of Cr(III) by H 2O 2

NASA Astrophysics Data System (ADS)

Pettine, Maurizio; Gennari, Francesca; Campanella, Luigi; Millero, Frank J.

2008-12-01

The oxidation of Cr(III) has been studied in NaCl solutions in the presence of two siderophore models, acetohydroxamic acid (Aha) and benzohydroxamic acid (Bha), the natural siderophore Desferal (DFOB) and the synthetic aminocarboxilate (ethylenedinitrilo)-tetra-acetic acid (EDTA) as a function of pH (8-9), ionic strength (0.01-2 M) and temperature (10-50 °C), at different Cr(III)-organic compound ratios. The addition of Aha and Bha caused the rates to increase at low ligand/Cr(III) ratios and decrease at high ratios. The variation of the pseudo first order rate constant ( k1) as a function of the ligand concentration has been attributed to the formation of three Cr(III)-organo species (1:1, 1:2, 1:3), which can form in the presence of monohydroxamic acids. A kinetic model has been developed that gives a value of 600 (min -1) for the pseudo first order rate constant k and values approaching zero for k and k. These kinetic results demonstrate that these monohydroxamic acids are able to bind with Cr(III) under experimental conditions that may occur in natural waters and can increase the oxidation rates of Cr(III) with H 2O 2 by a factor of 3.5 at an Aha/Cr(III) ratio of about 50-100. The monohydroxamic acids also affect the rates on aged products of Cr(III), suggesting that these ligands are able to affect the oxidation rates by releasing reactive Cr(III). DFOB and EDTA do not have a great effect on the oxidation of Cr(III) with H 2O 2. This is thought to be due to the much longer times they need to form complexes with Cr(III) compared to Aha and Bha. The rates for the formation of DFOB and EDTA complexes with Cr(III) are not competitive with the rates of the formation of aged Cr(III). After allowing Cr(III) and DFOB to react for 5 days to form the complex, reaction rates of Cr(III) with H 2O 2 appear to be lowered probably because of steric hindrance of the chelated Cr(III).

Magnetic biochar combining adsorption and separation recycle for removal of chromium in aqueous solution.

PubMed

Xin, Ouyang; Yitong, Han; Xi, Cao; Jiawei, Chen

2017-03-01

Biochar has been developed in recent years for the removal of contaminants such as Cr (VI) in water. The enhancement of the adsorption capacity of biochar and its recyclable use are still challenges. In this study, magnetic biochar derived from corncobs and peanut hulls was synthesized under different pyrolysis temperatures after pretreating the biomass with a low concentration of 0.5 M FeCl 3 solution. The morphology, specific surface area, saturation magnetization and Fourier transform infrared spectroscopy (FT-IR) spectra were characterized for biochar. The magnetic biochar performed well in combining adsorption and separation recycle for the removal of Cr (VI) in water. The Cr (VI) adsorbance of the biochar was increased with the increase in pyrolysis temperature, and the magnetic biochar derived from corncobs showed better performance for both magnetization and removal of Cr (VI) than that from peanut hulls. The Langmuir model was used for the isothermal adsorption and the maximum Cr (VI) adsorption capacity of corncob magnetic biochar pyrolyzed at 650 °C reached 61.97 mg/g. An alkaline solution (0.1 M NaOH) favored the desorption of Cr (VI) from the magnetic biochar, and the removal of Cr (VI) still remained around 77.6% after four cycles of adsorption-desorption. The results showed that corncob derived magnetic biochar is a potentially efficient and recoverable adsorbent for remediation of heavy metals in water.

Higher adsorption capacity of Spirulina platensis alga for Cr(VI) ions removal: parameter optimisation, equilibrium, kinetic and thermodynamic predictions.

PubMed

Gunasundari, Elumalai; Senthil Kumar, Ponnusamy

2017-04-01

This study discusses about the biosorption of Cr(VI) ion from aqueous solution using ultrasonic assisted Spirulina platensis (UASP). The prepared UASP biosorbent was characterised by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmet-Teller, scanning electron spectroscopy and energy dispersive X-ray and thermogravimetric analyses. The optimum condition for the maximum removal of Cr(VI) ions for an initial concentration of 50 mg/l by UASP was measured as: adsorbent dose of 1 g/l, pH of 3.0, contact time of 30 min and temperature of 303 K. Adsorption isotherm, kinetics and thermodynamic parameters were calculated. Freundlich model provided the best results for the removal of Cr(VI) ions by UASP. The adsorption kinetics of Cr(VI) ions onto UASP showed that the pseudo-first-order model was well in line with the experimental data. In the thermodynamic study, the parameters like Gibb's free energy, enthalpy and entropy changes were evaluated. This result explains that the adsorption of Cr(VI) ions onto the UASP was exothermic and spontaneous in nature. Desorption of the biosorbent was done using different desorbing agents in which NaOH gave the best result. The prepared material showed higher affinity for the removal of Cr(VI) ions and this may be an alternative material to the existing commercial adsorbents.

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

Karin Lundholm; Dan Bostroem; Anders Nordin

The EU Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. Chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60%more » arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO{sub 2}(s), (Fe,Mg,Cu)(Cr,Fe,Al)O{sub 4}(s), Cr{sub 2}O{sub 3}(s), and Ca{sub 3}(AsO{sub 4}){sub 2}(s). Arsenic was also identified in the fine particles as KH{sub 2}AsO{sub 4}(s) and As{sub 2}O{sub 3}). A strong indication of hexavalent chromium in the form of K{sub 2}CrO{sub 4} or as a solid solution between K{sub 3}Na(CrO{sub 4}){sub 2} and K{sub 3}Na(SO{sub 4}){sub 2} was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations. 38 refs., 6 figs., 2 tabs.« less

Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

PubMed

Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

2016-10-01

The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Hexavalent Chromium Causes the Oxidation of Thioredoxin in Human Bronchial Epithelial Cells

PubMed Central

Myers, Judith M.; Antholine, William E.; Myers, Charles R.

2008-01-01

Hexavalent chromium [Cr(VI)] species such as chromates are cytotoxic. Inhalational exposure is a primary concern in many Cr-related industries and their immediate environments, and bronchial epithelial cells are directly exposed to inhaled Cr(VI). Chromates are readily taken up by cells and are reduced to reactive Cr species which may also result in the generation of reactive oxygen species (ROS). The thioredoxin (Trx) system has a key role in the maintenance of cellular thiol redox balance and is essential for cell survival. Cells normally maintain the cytosolic (Trx1) and mitochondrial (Trx2) thioredoxins largely in the reduced state. Redox western blots were used to assess the redox status of the thioredoxins in normal human bronchial epithelial cells (BEAS-2B) incubated with soluble Na2CrO4 or insoluble ZnCrO4 for different periods of time. Both chromates caused a dose- and time-dependent oxidation of Trx2 and Trx1. Trx2 was more susceptible in that it could all be converted to the oxidized form, whereas a small amount of reduced Trx1 remained even after prolonged treatment with higher Cr concentrations. Only one of the dithiols, presumably the active site, of Trx1 was oxidized by Cr(VI). Cr(VI) did not cause significant GSH depletion or oxidation indicating that Trx oxidation does not result from a general oxidation of cellular thiols. With purified Trx and thioredoxin reductase (TrxR) in vitro, Cr(VI) also resulted in Trx oxidation. It was determined that purified TrxR has pronounced Cr(VI) reducing activity, so competition for electron flow from TrxR might impair its ability to reduce Trx. The in vitro data also suggested some direct redox interaction between Cr(VI) and Trx. The ability of Cr(VI) to cause Trx oxidation in cells could contribute to its cytotoxic effects, and could have important implications for cell survival, redox-sensitive cell signaling, and the cells' tolerance of other oxidant insults. PMID:18328613

Chromium-picolinate induced ocular changes: Protective role of ascorbic acid.

PubMed

Mahmoud, Amany A; Karam, Sawsan H; Abdel-Wahhab, Mosaad A

2006-09-21

Chromium-picolinate (Cr-picolinate) is a popular nutritional supplement; however its safety has been questioned with regard to its ability to act as a clastogen. The aim of the present work was to evaluate the biochemical, histological and morphological changes in the cornea and lens following oral administration of Cr-picolinate and the possible protective effect of Vitamin C. Ninety male Sprague-Dawley rats were divided into five groups included the control group, the groups treated with Cr-picolinate (0.8 and 1.5 mg/100 g b.w.) alone or in combination with Vitamin C (0.5 mg/100 g b.w.) for 8 weeks. The results indicated that the high dose of Cr-picolinate induced a significant decrease in SOD, GSH, Na(+)-, K(+)-ATPase levels, and a significant increase in MDA level. Severe morphological and histological changes in the cornea and lens accompanied with a decrease in the total soluble protein of the lens homogenate and changes in the crystalline fractions in lens. Vitamin C supplementation succeeded to restore these changes to great extent. It could be concluded that consumption of Cr-picolinate for a long time induced several hazards to cornea and lens. Supplementation with extra amounts of Vitamin C may be useful to restrain the Cr-picolinate induced ocular changes.

Evaluation of Cyclic Oxidation and Hot Corrosion Behavior of HVOF-Sprayed WC-Co/NiCrAlY Coating

NASA Astrophysics Data System (ADS)

Somasundaram, B.; Kadoli, Ravikiran; Ramesh, M. R.

2014-08-01

Corrosion of metallic structural materials at an elevated temperature in complex multicomponent gas environments are potential problems in many fossil energy systems, especially those using coal as a feedstock. Combating these problems involves a number of approaches, one of which is the use of protective coatings. The high velocity oxy fuel (HVOF) process has been used to deposit WC-Co/NiCrAlY composite powder on two types of Fe-based alloys. Thermocyclic oxidation behavior of coated alloys was investigated in the static air as well as in molten salt (Na2SO4-60%V2O5) environment at 700 °C for 50 cycles. The thermogravimetric technique was used to approximate the kinetics of oxidation. WC-Co/NiCrAlY coatings showed a lower oxidation rate in comparison to uncoated alloys. The oxidation resistance of WC-Co/NiCrAlY coatings can be ascribed to the oxide layer of Al2O3 and Cr2O3 formed on the outermost surface. Coated alloys extend a protective oxide scale composed of oxides of Ni and Cr that are known to impart resistance to the hot corrosion in the molten salt environment.

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.

Recyclable colorimetric sensor of Cr3 + and Pb2 + ions simultaneously using a zwitterionic amino acid modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Sang, Fuming; Li, Xin; Zhang, Zhizhou; Liu, Jia; Chen, Guofu

2018-03-01

In this work, a rapid, simple and sensitive colorimetric sensor for simultaneous (or respective) detection of Cr3 + and Pb2 + using tyrosine functionalized gold nanoparticles (AuNPsTyr) has been developed. Tyrosine, a natural and zwitterionic amino acid, could be as a reducing and capping agent to synthesise AuNPs and allow for the simultaneous and selective detection of Cr3 + and Pb2 +. Upon the addition of Cr3 + or Pb2 + (a combination of them), the color of AuNPsTyr solution changes from red to blue grey and the characteristic surface plasmon resonance (SPR) band is red-shifted to 580 nm due to the aggregation of AuNPs. Interestingly, the aggregated AuNPsTyr can be regnerated and recycled by removing Pb2 + and Cr3 +. Even after 3 rounds, AuNPsTyr show almost the same A580 nm / A520 nm value for the assays of Pb2 + and Cr3 +, indicating the good recyclability of the colorimetric sensor. The responding time (within 1 min) and sensitivity of the colorimetric sensor are largely improved after the addition of 0.1 M NaCl. Moreover, the AuNPsTyr aggregated by Cr3 + or Pb2 + (a combination of them) show excellent selectivity compared to other metal ions (Cr3 +, Pb2 +, Fe2 +,Cu2 +,Zn2 +,Cr6 +,Ni2 +,Co2 +,Hg2 +,Mn2 +,Mg2 +,Ca2 +,Cd2 +). More importantly, the developed sensor manifests good stability at room temperature for 3 months, which has been successfully used to determine Cr3 + and Pb2 + in the real water samples with a high sensitivity.

High-Temperature Exposure Studies of HVOF-Sprayed Cr3C2-25(NiCr)/(WC-Co) Coating

NASA Astrophysics Data System (ADS)

Singh, Harpreet; Kaur, Manpreet; Prakash, Satya

2016-08-01

In this research, development of Cr3C2-25(NiCr) + 25%(WC-Co) composite coating was done and investigated. Cr3C2-25(NiCr) + 25%(WC-Co) composite powder [designated as HP2 powder] was prepared by mechanical mixing of [75Cr3C2-25(NiCr)] and [88WC-12Co] powders in the ratio of 75:25 by weight. The blended powders were used as feedstock to deposit composite coating on ASTM SA213-T22 substrate using High Velocity Oxy-Fuel (HVOF) spray process. High-temperature oxidation/corrosion behavior of the bare and coated boiler steels was investigated at 700 °C for 50 cycles in air, as well as, in Na2SO4-82%Fe2(SO4)3 molten salt environment in the laboratory. Erosion-corrosion behavior was investigated in the actual boiler environment at 700 ± 10 °C under cyclic conditions for 1500 h. The weight-change technique was used to establish the kinetics of oxidation/corrosion/erosion-corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy-dispersive spectroscopy (FE-SEM/EDS), and EDS elemental mapping techniques were used to analyze the exposed samples. The uncoated boiler steel suffered from a catastrophic degradation in the form of intense spalling of the scale in all the environments. The oxidation/corrosion/erosion-corrosion resistance of the HVOF-sprayed HP2 coating was found to be better in comparison with standalone Cr3C2-25(NiCr) coating. A simultaneous formation of protective phases might have contributed the best properties to the coating.

The reduction of chromium (VI) by iron (II) in aqueous solutions

NASA Astrophysics Data System (ADS)

Pettine, Maurizio; D'Ottone, Luca; Campanella, Luigi; Millero, Frank J.; Passino, Roberto

1998-05-01

The rates of the reduction of Cr(VI) with Fe(II) were measured in NaCl, NaClO 4, and natural seawater as a function of pH (1.5-8.7), temperature (5-40°C) and ionic strength (I = 0.01-2 M). The pseudo first-order rate constant (log k 1) showed a parabolic dependence on pH decreasing from 1.5 to 4.5 and increasing from 5.5 to 8.7. The kinetics of the reaction in these two regions of pH also showed different influences of temperature, ionic strength, and reductant concentration. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k [Cr(VI)] [Fe(II)] where k (M -1 min -1) can be determined from the log k=6.74-1.01 pH-188.5/T for the pH range 1.5-4.5 (σ = 0.2) and log k=11.93+0.95 pH-4260.1/T-1.06 I 0.5 for the pH range 5-8.7 (σ = 0.2) from 5 to 40°C and 0.01 to 2 M ionic strength. The effect of pH, temperature, and ionic strength on the reaction indicates that the reactions at low pH are due to H2CrO4+ Fe2+limit→k H2 A-Feproducts While the reactions at high pH are due to HCrO4-+ FeOH+limit→k HA-FeOHproductsHCrO4-+ Fe(OH)2limit→k HA-Fe(OH)2 products The overall rate expression over the entire pH range can be determined from (H 2A = H 2CrO 4) k=k H2 A-Feα( H2A)α( Fe2+)+k HA-FeOHα( HA-)α( FeOH+)+k HA-Fe(OH)2 α( HA-)α( Fe(OH)2) where k H2A-Fe = 5 x 10 6, k HA-FeOH = 1 x 10 6, k HA-Fe (OH)2= 5 x 10 11. In oxic aqueous systems Cr(VI) competes with O 2 in the oxidation of Fe(II) and an extension of the rate law for Cr(VI) reduction with Fe(II) in oxygenated solutions is proposed. The application of this extended rate law to environmental conditions suggests that this reaction influences the distribution of oxidized and reduced species of chromium in oxic and anoxic waters.

Chromium (D-phenylalanine)3 improves obesity-induced cardiac contractile defect in ob/ob mice.

PubMed

Dong, Feng; Yang, Xiaoping; Sreejayan, Nair; Ren, Jun

2007-11-01

Low-molecular weight chromium compounds, such as chromium picolinate [Cr(pic)(3)], improve insulin sensitivity, although toxicity is a concern. We synthesized a novel chromium complex, chromium (d-phenylalanine)(3) [Cr(d-phe)(3)], in an attempt to improve insulin sensitivity with reduced toxicity. The aim of this study was to compare the two chromium compounds on cardiac contractile function in ob/ob obese mice. C57BL lean and ob/ob obese mice were randomly divided into three groups: H(2)O, Cr(d-phe)(3), or Cr(pic)(3) (45 mug/kg per day orally for 6 months). The glucose tolerance test displayed improved glucose clearance by Cr(d-phe)(3) but not Cr(pic)(3). Myocytes from ob/ob mice exhibited depressed peak shortening (PS) and maximal velocity of shortening/relengthening (+/-dL/dt), prolonged time-to-PS and time-to-90% relengthening (TR90), reduced electrically stimulated rise in intracellular Ca(2+) (Deltafura-2 fluorescence intensity), and slowed intracellular Ca(2+) decay. Although a 3-month Cr(d-phe)(3) treatment for a separate group of ob/ob and lean 2-month-old mice only rectified reduced +/-dL/dt in ob/ob mice, all mechanical and intracellular Ca(2+) abnormalities were significantly attenuated or ablated by 6 months of Cr(d-phe)(3) but not Cr(pic)(3) treatment (except TR90). Sarco(endo)plasmic reticulum Ca(2+) ATPase activity and Na(+)-Ca(2+) exchanger expression were depressed in ob/ob mice, which were reversed by both Cr(d-phe)(3) and Cr(pic)(3), with a more pronounced effect from Cr(d-phe)(3). Cr(d-phe)(3) corrected reduced insulin-stimulated glucose uptake and improved basal phosphorylation of Akt and insulin receptor, as well as insulin-stimulated phosphorylation of Akt and insulin receptor in ob/ob myocytes. Heart homogenates from ob/ob mice had enhanced oxidative stress and protein carbonyl formation compared with the lean group, which were attenuated by both Cr(d-phe)(3) and Cr(pic)(3). Our data suggest that the new Cr(d-phe)(3) compound possesses better cardio-protective and insulin-sensitizing properties against obesity.

Corrosion Behavior of Active Screen Plasma Nitrided 38CrMoAl Steel under Marine Environment

NASA Astrophysics Data System (ADS)

Yang, Li; He, Yongyong; Mao, JunYuan; Zhang, Lei

2017-10-01

The 38CrMoAl steels were nitrided at different temperatures for 7 h using active screen plasma discharge. The analysis showed that the thick compound layer composed of ɛ-Fe2-3N and γ‧-Fe4N was formed on the surface. The corrosion behavior was evaluated by measuring the anodic polarization curves in natural sea water (similar 3.5% NaCl solution), and observation of corroded surface were conducted. The electromechanical measurements indicated that the corrosion potential of the nitrided specimens shifted to a nobler value compared to that of untreated specimens. Passive regions were also observed in the polarization curves for all the nitrided specimens. These results indicate that active screen plasma nitriding can enhance the corrosion resistance of the 38CrMoAl steel under marine environment.

In vitro corrosion characteristics of commercially available orthodontic wires.

PubMed

Yonekura, Yasuyuki; Endo, Kazuhiko; Iijima, Masahiro; Ohno, Hiroki; Mizoguchi, Itaru

2004-06-01

The corrosion characteristics of orthodontic alloy wires were investigated both in as-received and grinded conditions in 0.9% NaCl solution by atomic absorption spectrophotometry and potentiodynamic polarization measurements. The amount of each metal ion released from most alloys was larger for the grinded wires than for the as-received wires (p<0.01). The fact that the beta-Ti alloy wire (Ti-Mo-Zr) does not contain allergenic metals such as Ni, Co, and Cr, and the finding that resistance to both general and localized corrosion is the highest among the six wires investigated suggest that this wire is the most biocompatible orthodontic wire. Since a small amount of Ni, Cr or Co ions were released from Ni-Ti, Co-Cr and stainless steel wires, special attention should be paid during their clinical use for patients with allergic tendencies.

Analyses of Mineral Content and Heavy Metal of Honey Samples from South and East Region of Turkey by Using ICP-MS.

PubMed

Kılıç Altun, Serap; Dinç, Hikmet; Paksoy, Nilgün; Temamoğulları, Füsun Karaçal; Savrunlu, Mehmet

2017-01-01

The substantial of mineral ingredients in honey may symbolize the existence of elements in the plants and soil of the vicinity wherein the honey was taken. The aim of this study was to detect the levels of 13 elements (Potassium (K), Sodium (Na), Calcium (Ca), Iron (Fe), Zinc (Zn), Cadmium (Cd), Copper (Cu), Manganese (Mn), Lead (Pb), Nickel (Ni), Chromium (Cr), Aluminum (Al), and Selenium (Se)) in unifloral and multifloral honey samples from south and east regions of Turkey. Survey of 71 honey samples from seven different herbal origins, picked up from the south and east region of Turkey, was carried out to determine their mineral contents during 2015-2016. The mineral contents were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The most abundant minerals were K, Na, and Ca ranging within 1.18-268 ppm, 0.57-13.1 ppm, and 0.77-4.5 ppm, respectively. Zn and Cu were the most abundant trace element while Pb, Cd, Ni, and Cr were the lowest heavy metals in the honey samples surveyed, with regard to the concentrations of heavy metals such as Zn, Cu, Pb, Cd, Ni, and Cr suggested and influence of the botanical origin of element composition. Geochemical and geographical differences are probably related to the variations of the chemical components of honey samples.

Thermodynamic model for solution behavior and solid-liquid equilibrium in Na-Al(III)-Fe(III)-Cr(III)-Cl-H2O system at 25°C

NASA Astrophysics Data System (ADS)

André, Laurent; Christov, Christomir; Lassin, Arnault; Azaroual, Mohamed

2018-03-01

The knowledge of the thermodynamic behavior of multicomponent aqueous electrolyte systems is of main interest in geo-, and environmental-sciences. The main objective of this study is the development of a high accuracy thermodynamic model for solution behavior, and highly soluble M(III)Cl3(s) (M= Al, Fe, Cr) minerals solubility in Na-Al(III)-Cr(III)-Fe(III)-Cl-H2O system at 25°C. Comprehensive thermodynamic models that accurately predict aluminium, chromium and iron aqueous chemistry and M(III) mineral solubilities as a function of pH, solution composition and concentration are critical for understanding many important geochemical and environmental processes involving these metals (e.g., mineral dissolution/alteration, rock formation, changes in rock permeability and fluid flow, soil formation, mass transport, toxic M(III) remediation). Such a model would also have many industrial applications (e.g., aluminium, chromium and iron production, and their corrosion, solve scaling problems in geothermal energy and oil production). Comparisons of solubility and activity calculations with the experimental data in binary and ternary systems indicate that model predictions are within the uncertainty of the data. Limitations of the model due to data insufficiencies are discussed. The solubility modeling approach, implemented to the Pitzer specific interaction equations is employed. The resulting parameterization was developed for the geochemical Pitzer formalism based PHREEQC database.

Chemoradiotherapy enhanced the efficacy of radiotherapy in nasopharyngeal carcinoma patients: a network meta-analysis

PubMed Central

He, Jian; Wu, Ping; Tang, Yaoyun; Liu, Sulai; Xie, Chubo; Luo, Shi; Zeng, Junfeng; Xu, Jing; Zhao, Suping

2017-01-01

Object A Bayesian network meta-analysis (NMA) was conducted to estimate the overall survival (OS) and complete response (CR) performance in nasopharyngeal carcinoma (NPC) patients who have been given the treatment of radiotherapy, concurrent chemoradiotherapy (C), adjuvant chemotherapy (A), neoadjuvant chemotherapy (N), concurrent chemoradiotherapy with adjuvant chemotherapy (C+A), concurrent chemoradiotherapy with neoadjuvant chemotherapy (C+N) and neoadjuvant chemotherapy with adjuvant chemotherapy (N+A). Methods Literature search was conducted in electronic databases. Hazard ratios (HRs) accompanied their 95% confidence intervals (95%CIs) or 95% credible intervals (95%CrIs) were applied to measure the relative survival benefit between two comparators. Meanwhile odd ratios (ORs) with their 95% CIs or CrIs were given to present CR data from individual studies. RESULTS Totally 52 qualified studies with 10,081 patients were included in this NMA. In conventional meta-analysis (MA), patients with N+C exhibited an average increase of 9% in the 3-year OS in relation to those with C+A. As for the NMA results, five therapies were associated with a significantly reduced HR when compared with the control group when concerning 5-year OS. C, C+A and N+A also presented a decreased HR compared with A. There was continuity among 1-year, 3-year and 5-year OS status. Cluster analysis suggested that the three chemoradiotherapy appeared to be divided into the most compete group which is located in the upper right corner of the cluster plot. Conclusion In view of survival rate and complete response, the NMA results revealed that C, C+A and C+N showed excellent efficacy. As a result, these 3 therapies were supposed to be considered as the first-line treatment according to this NMA. PMID:28418901

Marine and freshwater concentration ratios (CR(wo-water)): review of Japanese data.

PubMed

Tagami, K; Uchida, S

2013-12-01

The water-to-organism (whole body) concentration ratio (CR(wo-water)), which is defined as the ratio of the concentration of a radionuclide in the biota (Bq kg(-1) fresh weight) to that in water (Bq L(-1)), has been used in mathematical models for environmental radiation protection. In the present paper, published global fallout (90)Sr, (137)Cs, (106)Ru, (144)Ce and (239+240)Pu activity concentration data and stable element concentration data for Na, K, Ca, Mg, Fe, Cu and Mn for organisms living in freshwater or seawater areas in Japan were collated. The data suitable for obtaining CR(wo-water) values were identified. CR(wo-water) values of (137)Cs were similar for pelagic fish, benthic fish and whitebait (immature, small fish) with respective geometric means of 30 (range: 4.4-69), 32 (range: 15-54) and 33 (range: 13-84). The calculated CR(wo-water) values of the other radionuclides and stable elements were generally similar to other previously reported values; with the exception that those for Ce were lower for marine biota and those of Cu were higher for freshwater fish. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enhanced phosphate selectivity from wastewater using copper-loaded chelating resin functionalized with polyethylenimine.

PubMed

An, Byungryul; Nam, Juhee; Choi, Jae-Woo; Hong, Seok-Won; Lee, Sang-Hyup

2013-11-01

In water and wastewater, phosphate is considered a critical contaminant due to cause algae blooms and eutrophication. To meet the stringent regulation of phosphate in water, a new commercial chelating resin functionalized with polyethylenimine was tested for phosphate removal by loading Cu(2+) and Fe(2+)/Fe(3+) to enhance selectivity for phosphate. Batch and column experiments showed that CR20-Cu exhibited high selectivity for phosphate over other strong anions such as sulfate. The average binary phosphate/nitrate and phosphate/sulfate factors for CR20-Cu were calculated to be 7.3 and 4.8, respectively, which were more than 0.97 and 0.22 for a commercial anion exchanger (AMP16). The optimal pH for the phosphate removal efficiency was determined to be 7. According to the fixed-bed column test, the breakthrough sequence for multiple ions was HPO4(2-)>SO4(2-)>NO3(-)>Cl(-). Saturated CR20-Cu can be regenerated using 4% NaCl at pH 7. More than 95% of the phosphate from CR20-Cu was recovered, and the phosphate uptake capacity for CR20-Cu was not reduced after 7 regeneration cycles. Copyright © 2013 Elsevier Inc. All rights reserved.

Efficient anti-corrosive coating of cold-rolled steel in a seawater environment using an oil-based graphene oxide ink.

PubMed

Singhbabu, Y N; Sivakumar, B; Singh, J K; Bapari, H; Pramanick, A K; Sahu, Ranjan K

2015-05-07

We report the production of an efficient anti-corrosive coating of cold-rolled (CR) steel in a seawater environment (∼3.5 wt% NaCl aqueous solution) using an oil-based graphene oxide ink. The graphene oxide was produced by heating Aeschynomene aspera plant as a carbon source at 1600 °C in an argon atmosphere. The ink was prepared by cup-milling the mixture of graphene oxide and sunflower oil for 10 min. The coating of ink on the CR steel was made using the dip-coating method, followed by curing at 350 °C for 10 min in air atmosphere. The results of the potentiodynamic polarization show that the corrosion rate of bare CR steel decreases nearly 10,000-fold by the ink coating. Furthermore, the salt spray test results show that the red rusting in the ink-coated CR steel is initiated after 100 h, in contrast to 24 h and 6 h in the case of oil-coated and bare CR steel, respectively. The significant decrease in the corrosion rate by the ink-coating is discussed based on the impermeability of graphene oxide to the corrosive ions.

Installation Restoration Program. Volume 2. 110th Fighter Group Michigan Air National Guard, W.K. Kellogg Memorial Airport, Battle Creek, Michigan

DTIC Science & Technology

1993-11-01

RECOMMENDATIONS SECTION 7 REFERENCES APPENDIX A MONITORING WELL CONSTRUCTION RECORDS AND BORING LOGS APPENDIX B SOIL BORING LOGS 3 APPENDIX C ...0.25 .o000 2- C *LUOEITNYL VINYL ETNEE NA i2/o/U NP 0. 131.0ICNLORMTNMIE NA 12/OS/IS 0.35 0.0S 1.000 DIOCULUSUGRTNAN NA 12/OS/US a 0.45 1.000 ¶ ,2...12l/Sm a 10.001011 kS kfue(K)I m ot~b 12/09/ 12/fl/U a 10.00 1.005 ugejpvu 12/09/ tZ/3U 0 10.0 1 .M E, I c . ce 4Z- CR0ESFENGINEERING SCIENCE 135-073

Mineral Composition and Nutritive Value of Isotonic and Energy Drinks.

PubMed

Leśniewicz, Anna; Grzesiak, Magdalena; Żyrnicki, Wiesław; Borkowska-Burnecka, Jolanta

2016-04-01

Several very popular brands of isotonic and energy drinks consumed for fluid and electrolyte supplementation and stimulation of mental or physical alertness were chosen for investigation. Liquid beverages available in polyethylene bottles and aluminum cans as well as products in the form of tablets and powder in sachets were studied. The total concentrations of 21 elements (Ag, Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, Ti, V, and Zn), both essential and toxic, were simultaneously determined in preconcentrated drink samples by inductively coupled plasma-optical emission spectrometry (ICP-OES) equipped with pneumatic and ultrasonic nebulizers. Differences between the mineral compositions of isotonic and energy drinks were evaluated and discussed. The highest content of Na was found in both isotonic and energy drinks, whereas quite high concentrations of Mg were found in isotonic drinks, and the highest amount of calcium was quantified in energy drinks. The concentrations of B, Co, Cu, Ni, and P were higher in isotonic drinks, but energy drinks contained greater quantities of Ag, Cr, Zn, Mn, and Mo and toxic elements, as Cd and Pb. A comparison of element contents with micronutrient intake and tolerable levels was performed to evaluate contribution of the investigated beverages to the daily diet. The consumption of 250 cm(3) of an isotonic drink provides from 0.32% (for Mn) up to 14.8% (for Na) of the recommended daily intake. For the energy drinks, the maximum recommended daily intake fulfillment ranged from 0.02% (for V) to 19.4 or 19.8% (for Mg and Na).

Laser surface alloying of FeCoCrAlNi high-entropy alloy on 304 stainless steel to enhance corrosion and cavitation erosion resistance

NASA Astrophysics Data System (ADS)

Zhang, S.; Wu, C. L.; Zhang, C. H.; Guan, M.; Tan, J. Z.

2016-10-01

FeCoCrAlNi high-entropy alloy coating was synthesized with premixed high-purity Co, Cr, Al and Ni powders on 304 stainless steel by laser surface alloying, aiming at improving corrosion and cavitation erosion resistance. Phase constituents, microstructure and microhardness were investigated using XRD, SEM, and microhardness tester, respectively. The cavitation erosion and electrochemical corrosion behavior of FeCoCrAlNi coating in 3.5% NaCl solution were also evaluated using an ultrasonic vibrator and potentiodynamic polarization measurement. Experimental results showed that with appropriate laser processing parameters, FeCoCrAlNi coating with good metallurgical bonding to the substrate could be achieved. FeCoCrAlNi coating was composed of a single BCC solid solution. The formation of simple solid solutions in HEAs was the combined effect of mixing entropy (ΔSmix), mixing enthalpy (ΔHmix), atom-size difference (δ) and valence electron concentration (VEC), and the effect of ΔSmix was much larger than that of the other factors. The microhardness of the FeCoCrAlNi coating was ~3 times that of the 304 stainless steel. Both the corrosion and cavitation erosion resistance of the coating were improved. The cavitation erosion resistance for FeCoCrAlNi HEA coating was ~7.6 times that of 304 stainless steel. The corrosion resistance was also improved as reflected by a reduction in the current density of one order of magnitude as compared with 304 stainless steel.

Preparation of fluorinated Cr2O3 hexagonal prism and catalytic performance for the dehydrofluorination of 1,1-difluoroethane to vinyl fluoride

NASA Astrophysics Data System (ADS)

Han, Wenfeng; Li, Xiaojuan; Tang, Haodong; Wang, Zhikun; Xi, Miao; Li, Ying; Liu, Huazhang

2015-09-01

A Cr2O3 hexagonal prism structure synthesized via the reaction of aqueous CrCl3 solution with NaBH4 solution at room temperature followed by calcination of the precipitate in N2 atmosphere at 500 °C is investigated as an efficient catalyst for dehydrofluorination of 1,1-difluoroethane producing vinyl fluoride. With the assistance of scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy, experimental results revealed that the uniform hexagonal prism has a prism length of 285 ± 43 nm and width of 233 ± 33 nm. It is in the form of loose and net-like aggregation of nano-Cr2O3 with diameter less than 3-5 nm with polycrystalline structure. NH3 temperature programmed desorption and chlorodifluoromethane dismutation experiments confirm the existence of relatively abundant and strong acidic sites. As a catalyst for dehydrofluorination of 1,1-difluoroethane, compared with commercial Cr2O3, much higher activity and stability were observed due to the evolution of CrO x F y species and much higher surface area and mesoporous structure. No significant morphology changes or sintering of the catalyst are observed after 70-h reaction. Compared with the commercial Cr2O3, we suggest that the much smaller size of Cr2O3 crystalline which possesses higher surface energy, lower strength, and more abundant Lewis acidity and the formation of CrO x F y during reaction over hexagonal prism catalyst probably contributes to the activity and stability difference between these two catalysts.

Catalytic Silylation of N 2 and Synthesis of NH 3 and N 2H 4 by Net Hydrogen Atom Transfer Reactions Using a Chromium P 4 Macrocycle

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

Kendall, Alexander J.; Johnson, Samantha I.; Bullock, R. Morris

We report the first discrete molecular Cr-based catalysts for the reduction of N2. This study is focused on the reactivity of the Cr-N2 complex, trans-[Cr(N2)2(PPh4NBn4)] P4Cr(N2)2, bearing a 16-membered tetraphosphine macrocycle. The architecture of the [16]-PPh4NBn4 ligand is critical to preserve the structural integrity of the catalyst. P4Cr(N2)2 was found to mediate the reduction of N2 by three complementary reaction pathways: (1) Cr-catalyzed reduction of N2 to N(SiMe3)3 by Na and Me3SiCl affording up to 34 equiv N(SiMe3)3; (2) stoichiometric reduction of N2 by protons and electrons. For example, the reaction of cobaltocene (CoCp2) and collidinium triflate (ColH[OTf]) at roommore » temperature to afforded 1.9 equiv of NH3, or at -78 °C to afforded a mixture of NH3 and N2H4; (3) the first example of NH3 formation from the reaction of a terminally bound N2 ligand with a traditional H atom source, TEMPOH, (2,2,6,6-tetramethylpiperidine-1-ol). We found that trans-[Cr(15N2)2(PPh4NBn4)] reacts with excess TEMPOH to afford a 1.4 equiv of 15NH3.« less

Highly selective and sensitive colorimetric determination of Cr3 + ion by 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol functionalized Au nanoparticles

NASA Astrophysics Data System (ADS)

Shahrivari, Shima; Faridbod, Farnoush; Ganjali, Mohammad Reza

2018-02-01

In this work, a rapid, selective naked eyes colorimetric chemical probe for the detection of Cr3 + was developed based on functionalization of gold nanoparticles. For this purpose, surface of Au NPs was functionalized using 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol (AMTT). Through colorimetric studies, it was found that in the presence of Cr3 + ions, AMTT-Au NPs instantly aggregated and resulted in a color change of the solution from red to blue. The color change of AMTT-Au NPs due to the aggregation induced by Cr3 + can be seen with even naked eyes and also by UV-Vis spectroscopy with a detection limit of 1.8 μM and 0.1 μM, respectively. AMTT-Au NPs showed excellent selectivity toward Cr3 + compared to other cations tested, including K+, Na+, Cs+, Fe3 +, Ni2 +, Cu2 +, Co2 +, Zn2 +, Ba2 +, Ca2 +, Mg2 +, Cd2 +, Pb2 +, Hg2 + ions and especially all trivalent lanthanide ions. The absorbance ratio (A650/A525) was linear toward Cr3 + concentrations in the range of 0.6-6.1 μM (R2 = 0.996). The best response was achieved over a pH range of 3-5. Furthermore, the proposed colorimetric method based on AMTT-Au NPs was successfully used for Cr3 + ion detection in plasma sample and some water samples.

Spectrophotometric and electrochemical study for metal ion binding of azocalix[4]arene bearing p-ethylester group

NASA Astrophysics Data System (ADS)

Kim, Tae Hyun

2017-05-01

The complexation behavior of diazophenylcalix[4]arene bearing para-ethylester group (p-EAC) for alkali, alkaline earth, various heavy and transition metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2 +, Ca2 +, Sr2 +, Ba2 +, Cr3 +, Fe2 +, Co2 +, Ni2 +, Cu2 +, Zn2 +, Pb2 +) was investigated by spectrophotometric and electrochemical methods in CH3CN. p-EAC exhibits decreased absorbance at 353 nm in the presence of Cr3 +, Fe2 +, Pb2 +, and Cu2 +. The spectra of p-EAC showed bathochromic shift in absorption maximum on the addition of Cr3 +, Fe2 +, or Pb2 + with decreasing order of absorbance (Cr3 + > Fe2 + > Pb2 +), and on the other hand, hypsochromic shift on the addition of Cu2 +. This leads to the selective coloration from light green to orange and colorless for Cr3 + and Cu2 + that can be detected by the naked eye, respectively. In electrochemistry experiments, p-EAC also showed two different types of voltammetric changes toward Cr3 +, Fe2 +, or Pb2 +, and toward Cu2 +, whereas no significant changes occurred in the presence of the other metal ions. Nonlinear fitting curve procedure was used to determine a logarithmic value of 5.20, 4.92, 3.54 and 4.80 for the stability constants of the complex of p-EAC with Cr3 +, Fe2 +, Pb2 +, and Cu2 +, respectively.

Study of the effects of gaseous environments on the hot corrosion of superalloy materials

NASA Technical Reports Server (NTRS)

Smeggil, J. G.; Bornstein, N. S.

1980-01-01

The effect of the gaseous corrodent NaCl on the high temperature oxidation and sodium sulfate induced hot corrosion behavior of alumina formers, chromia formers, and the superalloy B-1900 was examined. Isothermal experiments were conducted at 900 C and 1050 C in air in the presence and absence of NaCl vapors. Microstructural changes in oxide morphology and increased rates of oxidation were observed when NaCl(g) was present. It is hypothesized that the accelerated rates of oxidation are the result of removal of aluminum from the scale substrate interface and the weakening of the scale substrate bonds. The aluminum removed was redeposited on the surfaces in the form of alumina whiskers. For the superalloy B-1900, alumina whiskers are also formed, and the alloy oxidizes at catastrophic rates. In the case of Ni-25Cr alloy, NaCl vapors interact with the scale depleting it of chromium.

Reduction of aqueous chromate by Fe(II)/Fe(III) carbonate green rust: kinetic and mechanistic studies.

PubMed

Legrand, Ludovic; El Figuigui, Alaaeddine; Mercier, Florence; Chausse, Annie

2004-09-01

This work describes the heterogeneous reaction between FeII in carbonate green rust and aqueous chromate, in NaHCO3 solutions at 25 degrees C, and at pH values of 9.3-9.6. Evidence for reduction of CrVI to CrIII and concomitant solid-state oxidation of lattice FeII to FeIII was found from FeII titration and from structural analysis of the solids using FTIR, XRD, SEM, and XPS methods. Results indicate the formation of ferric oxyhydroxycarbonate and the concomitant precipitation of CrIII monolayers at the surface of the iron compound that induce passivation effects and progressive rate limitations. The number of CrIII monolayers formed at the completion of the reaction depends on [FeII]t=0, the molar concentration of FeII(solid) at t=0; on [n(o)]t=0, the molar concentration of reaction sites present at the surface of the solid phase at t=0; and on [CrVI]t=0, the molar concentration of CrVI at t=0. Kinetic data were modeled using a model based on the formation of successive CrIII monolayers, -(d[CrVI]/dt) = sigma(1)j k(i)[S] [CrVI]([n(i - 1)] - [n(i)]) with k(i)[S] (in s(-1) L mol(-1)), the rate coefficient of formation of CrIII monolayer i, and [n(i)] and [n(i - 1)], the molar concentration of CrIII precipitated in monolayer i and monolayer i - 1, respectively. Good matching curves were obtained with kinetic coefficients: k(1)[S] = 5-8 x 10(-4), k(2)[S] = 0.5-3 x 10(-5), and k(3)[S] about 1.7 x 10(-6) s(-1) m(-2) L. The CrVI removal efficiency progressively decreases along with the accumulation of CrIII monolayers at the surface of carbonate green rust particles. In the case of thick green rust particles resulting from the corrosion of iron in permeable reactive barriers, the quantity of FeII readily accessible for efficient CrVI removal should be rather low.

An exploratory study on low-concentration hexavalent chromium adsorption by Fe(III)-cross-linked chitosan beads

PubMed Central

Zhang, Yuanjing; Qian, Jin; Xin, Xu; Hu, Sihai; Zhang, Shuai; Wei, Jianguo

2017-01-01

In this study, Fe(III)-cross-linked chitosan beads (Fe(III)-CBs) were synthesized and employed to explore the characteristics and primary mechanism of their hexavalent chromium (Cr(VI)) adsorption under low concentration Cr(VI) (less than 20.0 mg l−1) and a pH range from 2.0 to 8.0. Batch tests were conducted to determine the Cr(VI) adsorption capacity and kinetics, and the effects of pH and temperature on the adsorption under low concentration Cr(VI) and a pH range from 2.0 to 8.0. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were employed to explore the characteristics of Fe(III)-CBs and their Cr(VI) adsorption mechanisms. The results show that, unlike the adsorption of other absorbents, the Cr(VI) adsorption was efficient in a wide pH range from 2.0 to 6.0, and well described by the pseudo-first-order model and the Langmuir–Freundlich isotherm model. The capacity of Cr(VI) adsorption by Fe(III)-CBs was as high as 166.3 mg g−1 under temperature 25°C and pH 6.0. The desorption test was also carried out by 0.1 mol l−1 NaOH solution for Fe(III)-CBs regeneration. It was found that Fe(III)-CBs could be re-used for five adsorption–desorption cycles without significant decrease in Cr(VI) adsorption capacity. Ion exchange was confirmed between functional groups (i.e. amino group) and Cr(VI) anions (i.e. CrO42−). The amino-like functional groups played a key role in Cr(VI) distribution on the Fe(III)-CBs surface; Cr(VI) adsorbed on Fe(III)-CBs was partially reduced to Cr(III) with alcoholic group served as electron donor, and then formed another rate-limiting factor. So, Fe(III)-CBs has a good prospect in purifying low concentration Cr(VI) water with a pH range from 2.0 to 6.0. PMID:29291084

Topotactic redox chemistry of NaFeAs in water and air and superconducting behavior with stoichiometry change.

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

Todorov, I.; Chung, D. Y.; Claus, H.

2010-07-13

We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na deficient. The oxidation of NaFeAs progresses differently in water and in air. In water the material oxidizes slowly and slightly retaining the original anti-PbFCl structure. In air NaFeAs oxidizes topotactically quickly and extensively transforming to the ThCr{sub 2}Si{sub 2} structure type. Water acts as a mild oxidizing agent on the FeAs layer by extracting electrons and Na{sup +} cations from the structure, while oxidation in air is more extensive and leads to change in structure type from NaFeAs to NaFe{sub 2}As{sub 2}. The superconducting transition temperaturemore » moves dramatically during the oxidation process. Exposed to water for an extended time period NaFeAs shows a substantial increase in T{sub c} up to 25 K with contraction of unit cell volume. NaFe{sub 2}As{sub 2}, the air oxidized product, shows T{sub c} of 12 K. We report detailed characterization of the redox chemistry and transformation of NaFeAs in water and air using single crystal and powder X-ray diffraction, magnetization studies, transmission electron microscopy, Moessbauer spectroscopy, pOH and elemental analysis.« less

Mass spectrometry analysis of etch products from CR-39 plastic irradiated by heavy ions

NASA Astrophysics Data System (ADS)

Kodaira, S.; Nanjo, D.; Kawashima, H.; Yasuda, N.; Konishi, T.; Kurano, M.; Kitamura, H.; Uchihori, Y.; Naka, S.; Ota, S.; Ideguchi, Y.; Hasebe, N.; Mori, Y.; Yamauchi, T.

2012-09-01

As a feasibility study, gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) have been applied to analyze etch products of CR-39 plastic (one of the most frequently used solid states nuclear track detector) for the understanding of track formation and etching mechanisms by heavy ion irradiation. The etch products of irradiated CR-39 dissolved in sodium hydroxide solution (NaOH) contain radiation-induced fragments. For the GC-MS analysis, we found peaks of diethylene glycol (DEG) and a small but a definitive peak of ethylene glycol (EG) in the etch products from CR-39 irradiated by 60 MeV N ion beams. The etch products of unirradiated CR-39 showed a clear peak of DEG, but no other significant peaks were found. DEG is known to be released from the CR-39 molecule as a fragment by alkaline hydrolysis reaction of the polymer. We postulate that EG was formed as a result of the breaking of the ether bond (C-O-C) of the DEG part of the CR-39 polymer by the irradiation. The mass distribution of polyallylalcohol was obtained from the etch products from irradiated and unirradiated CR-39 samples by MALDI-MS analysis. Polyallylalcohol, with the repeating mass interval of m/z = 58 Da (dalton) between m/z = 800 and 3500, was expected to be produced from CR-39 by alkaline hydrolysis. We used IAA as a matrix to assist the ionization of organic analyte in MALDI-MS analysis and found that peaks from IAA covered mass spectrum in the lower m/z region making difficult to identify CR-39 fragment peaks which were also be seen in the same region. The mass spectrometry analysis using GC-MS and MALDI-MS will be powerful tools to investigate the radiation-induced polymeric fragments and helping to understand the track formation mechanism in CR-39 by heavy ions.

FAST TRACK COMMUNICATION: Pyroxenes: a new class of multiferroics

NASA Astrophysics Data System (ADS)

Jodlauk, S.; Becker, P.; Mydosh, J. A.; Khomskii, D. I.; Lorenz, T.; Streltsov, S. V.; Hezel, D. C.; Bohatý, L.

2007-10-01

Pyroxenes with the general formula AMSi2O6 (A = mono- or divalent metal, M = di- or trivalent metal) are shown to be a new class of multiferroic materials. In particular, we have found so far that NaFeSi2O6 becomes ferroelectric in a magnetically ordered state below ~6 K. Similarly, magnetically driven ferroelectricity is also detected in the Li homologues, LiFeSi2O6 (TC~18 K) and LiCrSi2O6 (TC~11 K). In all these monoclinic systems the electric polarization can be strongly modified by magnetic fields. Measurements of magnetic susceptibility, pyroelectric current and dielectric constants (and their dependence on magnetic field) are performed using a natural crystal of aegirine (NaFeSi2O6) and synthetic crystals of LiFeSi2O6 and LiCrSi2O6 grown from melt solution. For NaFeSi2O6 a temperature versus magnetic field phase diagram is proposed. Exchange constants are computed on the basis of ab initio band structure calculations. The possibility of a spiral magnetic structure caused by frustration to be the reason for the origin of the multiferroic behaviour is discussed. We propose that other pyroxenes may also be multiferroic, and that the versatility of this family offers an exceptional opportunity to study general conditions for and mechanisms of magnetically driven ferroelectricity.

Response of CR-39 to 0.9-2.5 MeV protons for KOH and NaOH etching solutions

NASA Astrophysics Data System (ADS)

Bahrami, F.; Mianji, F.; Faghihi, R.; Taheri, M.; Ansarinejad, A.

2016-03-01

In some circumstances passive detecting methods are the only or preferable measuring approaches. For instance, defining particles' energy profile inside the objects being irradiated with heavy ions and measuring fluence of neutrons or heavy particles in space missions are the cases covered by these methods. In this paper the ability of polyallyl diglycol carbonate (PADC) track detector (commercially known as CR-39) for passive spectrometry of proton particles is studied. Furthermore, the effect of KOH and NaOH as commonly used chemical etching solutions on the response of the detector is investigated. The experiments were carried out with protons in the energy range of 0.94-2.5 MeV generated by a Van de Graaff accelerator. Then, the exposed track dosimeters were etched in the two aforementioned etchants through similar procedure with the same normality of 6.25 N and the same temperature of 85 °C. Formation of the tracks was precisely investigated and the track diameters were recorded following every etching step for each solution using a multistage etching process. The results showed that the proposed method can be efficiently used for the spectrometry of protons over a wider dynamic range and with a reasonable accuracy. Moreover, NaOH and KOH outperformed each other over different regions of the proton energy range. The detection efficiency of both etchants was approximately 100%.

Bioactive glass coatings for orthopedic metallic implants

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

Lopez-Esteban, Sonia; Saiz, Eduardo; Fujino, Sigheru

2003-06-30

The objective of this work is to develop bioactive glass coatings for metallic orthopedic implants. A new family of glasses in the SiO2-Na2O-K2O-CaO-MgO-P2O5 system has been synthesized and characterized. The glass properties (thermal expansion, softening and transformation temperatures, density and hardness) are in line with the predictions of established empirical models. The optimized firing conditions to fabricate coatings on Ti-based and Co-Cr alloys have been determined and related to the glass properties and the interfacial reactions. Excellent adhesion to alloys has been achieved through the formation of 100-200 nm thick interfacial layers (Ti5Si3 on Ti-based alloys and CrOx on Co-Cr).more » Finally, glass coatings, approximately 100 mu m thick, have been fabricated onto commercial Ti alloy-based dental implants.« less

ESCA study of oxidation and hot corrosion of nickel-base superalloys. [Electron Spectroscopy for Chemical Analysis

NASA Technical Reports Server (NTRS)

Smith, S. R.; Carter, W. J., III; Mateescu, G. D.; Kohl, F. J.; Fryburg, G. C.; Stearns, C. A.

1980-01-01

A study of the high-temperature oxidation and Na2SO4-induced hot corrosion of nickel-base superalloys has been accomplished by using ESCA to determine the surface composition of the oxidized or corroded samples. Oxidation was carried out at 900 or 1000 C in slowly flowing O2 for samples of B-1900, NASA-TRW VIA, 713C, and IN-738. Hot corrosion of B-1900 was induced by applying a coating of Na2SO4 to preoxidized samples, then heating to 900 C in slowly flowing O2. For oxidized samples, the predominant type of scale formed by each superalloy showed a marked surface enrichment of Ti. For corroded samples, the transfer of significant amounts of material from the oxide layer to the surface of the salt layer was observed before the onset of rapidly accelerating weight gain. Marked changes in surface composition coincided with the beginning of accelerating corrosion, the most striking of which were a tenfold decrease in the sulfur to sodium ratio and an increase in the Cr(VI) to Cr(III) ratio.

Bioaugmentation in growing plants for lunar bases

NASA Astrophysics Data System (ADS)

Zaets, I.; Burlak, O.; Rogutskyy, I.; Vasilenko, A.; Mytrokhyn, O.; Lukashov, D.; Foing, B.; Kozyrovska, N.

2011-03-01

Microorganisms may be a key element in a precursory scenario of growing pioneer plants for extraterrestrial exploration. They can be used for plant inoculation to leach nutritional elements from regolith, to alleviate lunar stressors, as well as to decompose both lunar rocks and the plant straw in order to form a protosoil. Bioleaching capacities of both French marigold (Tagetes patula L.) and the associated bacteria in contact with a lunar rock simulant (terrestrial anorthosite) were examined using the model plant-bacteria microcosms under controlled conditions. Marigold accumulated K, Na, Fe, Zn, Ni, and Cr at higher concentrations in anorthosite compared to the podzol soil. Plants inoculated with the consortium of well-defined species of bacteria accumulated higher levels of K, Mg, and Mn, but lower levels of Ni, Cr, Zn, Na, Ca, Fe, which exist at higher levels in anorthosite. Bacteria also affected the Са/Mg and Fe/Mn ratios in the biomass of marigold grown on anorthosite. Despite their growth retardation, the inoculated plants had 15% higher weight on anorthosite than noninoculated plants. The data suggest that the bacteria supplied basic macro-and microelements to the model plant.

Corrosion behavior of high-nickel and chromium alloys in natural Baltic seawater

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

Birn, J.; Janik-Czachor, M.; Wolowik, A.

Effect of Cl{sup {minus}} ion concentration (O M sodium chloride [NaCl] to 2 M NaCl) and temperature (25 C to 75 C) on stability of the passive state of high-Ni and Cr alloys: NI-1 ({approximately} 16% Mo), CR-2 ({approximately} 6.2% Mo), and NI-3 (3.5% Mo) were investigated in acidic and neutral electrolytes in strictly controlled electrochemical conditions. The anodic behavior of the alloys appeared to depend mostly upon Mo content in the alloy. Thus, the NI-1 was the most stable alloy under the applied experimental conditions. The other alloys were also quite resistant, undergoing pitting only at elevated temperatures, atmore » high anodic potentials, and at a chloride concentration not lower than 1 M. In natural Baltic seawater, these alloys did not exhibit any tendency to pitting, in qualitative agreement with the accelerated electrochemical tests. Complementary microscopic and surface analytical (AES) investigations were carried out to correlate the anodic and corrosion behavior of these materials with their composition and structure, and the composition of the passivating films formed at their surfaces.« less

[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.

[Adsorptive Stabilization of Soil Cr (VI) Using HDTMA Modified Montmorillonite].

PubMed

2016-03-15

A series of organo-montomorillonites were prepared using Na-montomorillonite and hexadecyl trimethyl ammonium bromide (HDTMA). The organo-montomorillonites were then investigated for the remediation of Cr(VI) contaminated soils. FT-IR, XRD, SEM and N2 -BET, CEC, Zeta potential measurement were conducted to understand the structural changes of montmorillonites as different amounts of HDTMAs were added as modifier. The characterization results indicated that the clay interlayer spacing distance increased from 1. 25 nm to 2. 13 nm, the clay surface roughness decreased, the clay surface area reduced from 38.91 m² · g⁻¹ to 0.42 m² · g⁻¹, the clay exchangeable cation amount reduced from 62 cmol · kg⁻¹ to 9.9 cmol · kg⁻¹ and the clay surface charge changed from -29.1 mV to 5.59 mV as the dosage of HDTMA in montmorillonite was increased. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of Cr(VI). The effects of the initial soil Cr(VI) concentration, montmorillonites dosage, reaction time and HDTMA modification amount were investigated, respectively. The results revealed that modification of montmorillonites would manifest an attenuated physical adsorptive effect and an enhanced electrostatic adsorptive effect on Cr(VI), suggesting electrostatic effect was the major force that resulted in improved Cr(VI) adsorption onto HDTMA modified montmorillonites.

Effects of seawater acclimation on mRNA levels of corticosteroid receptor genes in osmoregulatory and immune systems in trout

USGS Publications Warehouse

Yada, T.; Hyodo, S.; Schreck, C.B.

2008-01-01

Influence of environmental salinity on expression of distinct corticosteroid receptor (CR) genes, glucocorticoid receptor (GR)-1 and -2, and mineralcorticoid receptor (MR), was examined in osmoregulatory and hemopoietic organs and leucocytes of steelhead trout (Oncorhynchus mykiss). There was no significant difference in plasma cortisol levels between freshwater (FW)- or seawater (SW)-acclimated trout, whereas Na+, K+-ATPase was activated in gill of SW fish. Plasma lysozyme levels also showed a significant increase after acclimation to SW. In SW-acclimated fish, mRNA levels of GR-1, GR-2, and MR were significantly higher in gill and body kidney than those in FW. Head kidney and spleen showed no significant change in these CR mRNA levels after SW-acclimation. On the other hand, leucocytes isolated from head kidney and peripheral blood showed significant decreases in mRNA levels of CR in SW-acclimated fish. These results showed differential regulation of gene expression of CR between osmoregulatory and immune systems. ?? 2008 Elsevier Inc. All rights reserved.

Dissolved Concentrations, Sources, and Risk Evaluation of Selected Metals in Surface Water from Mangla Lake, Pakistan

PubMed Central

Saleem, Muhammad; Iqbal, Javed; Shah, Munir H.

2014-01-01

The present study is carried out for the assessment of water quality parameters and selected metals levels in surface water from Mangla Lake, Pakistan. The metal levels (Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were determined by flame atomic absorption spectrophotometry. Average levels of Cd, Co, Cr, Ni, and Pb were higher than the allowable concentrations set by national and international agencies. Principal component analysis indicated significant anthropogenic contributions of Cd, Co, Cr, Ni, and Pb in the water reservoir. Noncarcinogenic risk assessment was then evaluated using Hazard Quotient (HQing/derm) and Hazard Index (HIing/derm) following USEPA methodology. For adults and children, Cd, Co, Cr, and Pb (HQing > 1) emerged as the most important pollutants leading to noncarcinogenic concerns via ingestion route, whereas there was no risk via dermal contact of surface water. This study helps in establishing pollutant loading reduction goal and the total maximum daily loads, and consequently contributes to preserve public health and develop water conservation strategy. PMID:24744690

Rice seed toxicity tests for organic and inorganic substances

USGS Publications Warehouse

Wang, W.

1994-01-01

Plant seed toxicity tests can be used to evaluate hazardous waste sites and to assess toxicity of complex effluents and industrial chemicals. Conventional plant seed toxicity tests are performed using culture dishes containing filter paper. Some reports indicate that filter papers might interfere with the toxicity of inorganic substances. In this study, a plastic seed tray was used. Rice was used as the test species. A comparison of results in the literature and this study revealed that variation of test species, methods, exposure duration, and other factors may affect the test results. The results of this study showed that the order of decreasing toxicity of metal ions was Cu>Ag>Ni>Cd>Cr(VI)>Pb>Zn>Mn>NaF for rice. The test results were similar to those reported in the literature for lettuce Ag>Ni>Cd,Cu>Cr (VI)>Zn>Mn, millet Cu,Ni>Cd>Cr(VI)>Zn>Mn, and ryegrass Cu>Ni>Mn>>Pb>Cd>Zn> Al>Hg>Cr>Fe. The order of decreasing toxicity of organic herbicides was paraquat, 2,4-D>>glyphosate>bromacil.

The Effect of the Concentration of Oxidant, Cr(VI), on the Iron Oxidation in Saline Water

NASA Astrophysics Data System (ADS)

Ahn, H.; Jo, H. Y.; Ryu, J. H.; Koh, Y. K.

2014-12-01

Deep geological disposal is currently considered as the most appropriate method to isolate high level radioactive wastes (HLRWs) from the ecosystem. If groundwater seeps into underground disposal facilities, water molecules can be dissociated to radicals or peroxides, which can oxidize metal canisters and HLRWs. The oxidized radionuclides with a high solubility can be dissolved in the groundwater. Some dissolved radionuclides can act as oxidants. The continuous radiolysis of water molecules, which results from continuous seepage of groundwater, can enable the continuous production of the radioactive oxidants, resulting in an increase in concentration of oxidants. In this study, the effect of oxidant concentration on iron oxidation in the presence of salt was evaluated. Zero valent iron (ZVI) particles were reacted with Cr(VI) solutions with initial Cr(VI) concentrations ranged from 50 to 300 mg/L in reactors. The initial pH and NaCl concentration were fixed at 3 and 0.5 M, respectively. An increase in the initial Cr(VI) concentration caused an increase in the rate and extend of H2 gas production. The decrement of Cr(VI) was increased as the initial Cr(VI) concentration was increased. The penetration of H+ ions in the presence Cl- ions through the passive film on the ZVI particles caused the reaction between H+ ions and ZVI particles, producing H2 gas and Fe2+ ions. The passive film was damaged during the reaction due to the eruption of H2 gas or peptization by Cl- ions. The Fe2+ ions were reacted with Cr(VI) ions in the solution, producing Fe(III)-Cr(III) (oxy)hydroxides on the passive film of ZVI particles or in the solution as colloidal particles. The Fe(III)-Cr(III) (oxy)hydroxides tends to be precipitated as colloidal particles at a high Cr(VI) concentration and precipitated on the passive film at a low Cr(VI) concentration. The passive film was repaired or thickened by additional formation of Fe(III)-Cr(III) (oxy)hydroxides at a lower Cr(VI) concentration.

An investigation of passivity and breakdown of amorphous chromium-bromine thin films for surface modification of metallic biomaterials

NASA Astrophysics Data System (ADS)

Cormier, Lyne Mercedes

1998-12-01

The objectives of this investigation of amorphous Cr-B thin films as prospective coatings for biomaterials applications were to (i) produce and characterize an amorphous Cr-B thin film coating by magnetron sputtering, (ii) evaluate its corrosion resistance in physiologically relevant electrolytes, and (iii) propose a mechanism for the formation/dissolution of the passive film formed on amorphous Cr-B in chloride-containing near-neutral salt electrolytes. Dense (zone T) amorphous Cr75B25 thin films produced by DC magnetron sputtering were found to be better corrosion barriers than nanoczystalline or porous (zone 1) amorphous Cr75B25 thin films. The growth morphology and microstructure were a function of the sputtering pressure and substrate temperature, in agreement with the structure zone model of Thornton. The passivity/loss of passivity of amorphous Cr 75B25 in near-neutral salt solutions was explained using a modified bipolar layer model. The chromate ions identified by X-Ray Photoelectron Spectroscopy (XPS) in the outer layer of the passive film were found to play a determinant role in the passive behaviour of amorphous Cr75B 25 thin films in salt solutions. In near-neutral salt solutions of pH = 5 to 7, a decrease in pH combined with an increase in chloride concentration resulted in less dissolution of the Cr75B25 thin films. The apparent breakdown potential at 240 mV (SCE) obtained by Cyclic Potentiodynamic Anodic Polarization (CPAP) was associated with oxidation of species within the passive film, but not to dissolution leading to immediate loss of passivity. Pit Propagation Rate (PPR) testing evaluated the stable pitting potential to be between 600 and 650 mV. Amorphous Cr75B25 thin films ranked the best among other Cr-based materials such as 316L stainless steel, CrB2 and Cr investigated in this study for general corrosion behaviour in NaCl and Hanks solutions by CPAP testing. In terms of corrosion resistance, amorphous Cr75B25 thin films were recognized as a promising material for surface modification of biomaterials.

Estimated Prevalence of Cryptococcus Antigenemia (CrAg) among HIV-Infected Adults with Advanced Immunosuppression in Namibia Justifies Routine Screening and Preemptive Treatment.

PubMed

Sawadogo, Souleymane; Makumbi, Boniface; Purfield, Anne; Ndjavera, Christophine; Mutandi, Gram; Maher, Andrew; Kaindjee-Tjituka, Francina; Kaplan, Jonathan E; Park, Benjamin J; Lowrance, David W

2016-01-01

Cryptococcal meningitis is common and associated with high mortality among HIV infected persons. The World Health Organization recommends that routine Cryptococcal antigen (CrAg) screening in ART-naïve adults with a CD4+ count <100 cells/μL followed by pre-emptive antifungal therapy for CrAg-positive patients be considered where CrAg prevalence is ≥3%. The prevalence of CrAg among HIV adults in Namibia is unknown. We estimated CrAg prevalence among HIV-infected adults receiving care in Namibia for the purpose of informing routine screening strategies. The study design was cross-sectional. De-identified plasma specimens collected for routine CD4+ testing from HIV-infected adults enrolled in HIV care at 181 public health facilities from November 2013 to January 2014 were identified at the national reference laboratory. Remnant plasma from specimens with CD4+ counts <200 cells/μL were sampled and tested for CrAg using the IMMY® Lateral Flow Assay. CrAg prevalence was estimated and assessed for associations with age, sex, and CD4+ count. A total of 825 specimens were tested for CrAg. The median (IQR) age of patients from whom specimens were collected was 38 (32-46) years, 45.9% were female and 62.9% of the specimens had CD4 <100 cells/μL. CrAg prevalence was 3.3% overall and 3.9% and 2.3% among samples with CD4+ counts of CD4+<100 cells/μL and 100-200 cells/μL, respectively. CrAg positivity was significantly higher among patients with CD4+ cells/μL < 50 (7.2%, P = 0.001) relative to those with CD4 cells/μL 50-200 (2.2%). This is the first study to estimate CrAg prevalence among HIV-infected patients in Namibia. CrAg prevalence of ≥3.0% among patients with CD4+<100 cells/μL justifies routine CrAg screening and preemptive treatment among HIV-infected in Namibia in line with WHO recommendations. Patients with CD4+<100 cells/μL have a significantly greater risk for CrAg positivity. Revised guidelines for ART in Namibia now recommend routine screening for CrAg.

Source apportionment of airborne particulates through receptor modeling: Indian scenario

NASA Astrophysics Data System (ADS)

Banerjee, Tirthankar; Murari, Vishnu; Kumar, Manish; Raju, M. P.

2015-10-01

Airborne particulate chemistry mostly governed by associated sources and apportionment of specific sources is extremely essential to delineate explicit control strategies. The present submission initially deals with the publications (1980s-2010s) of Indian origin which report regional heterogeneities of particulate concentrations with reference to associated species. Such meta-analyses clearly indicate the presence of reservoir of both primary and secondary aerosols in different geographical regions. Further, identification of specific signatory molecules for individual source category was also evaluated in terms of their scientific merit and repeatability. Source signatures mostly resemble international profile while, in selected cases lack appropriateness. In India, source apportionment (SA) of airborne particulates was initiated way back in 1985 through factor analysis, however, principal component analysis (PCA) shares a major proportion of applications (34%) followed by enrichment factor (EF, 27%), chemical mass balance (CMB, 15%) and positive matrix factorization (PMF, 9%). Mainstream SA analyses identify earth crust and road dust resuspensions (traced by Al, Ca, Fe, Na and Mg) as a principal source (6-73%) followed by vehicular emissions (traced by Fe, Cu, Pb, Cr, Ni, Mn, Ba and Zn; 5-65%), industrial emissions (traced by Co, Cr, Zn, V, Ni, Mn, Cd; 0-60%), fuel combustion (traced by K, NH4+, SO4-, As, Te, S, Mn; 4-42%), marine aerosols (traced by Na, Mg, K; 0-15%) and biomass/refuse burning (traced by Cd, V, K, Cr, As, TC, Na, K, NH4+, NO3-, OC; 1-42%). In most of the cases, temporal variations of individual source contribution for a specific geographic region exhibit radical heterogeneity possibly due to unscientific orientation of individual tracers for specific source and well exaggerated by methodological weakness, inappropriate sample size, implications of secondary aerosols and inadequate emission inventories. Conclusively, a number of challenging issues and specific recommendations have been included which need to be considered for a scientific apportionment of particulate sources in different geographical regions of India.

Experimental calibration of Forsterite-Anorthite-Ca-Tschermak-Enstatite (FACE) geobarometer for mantle peridotites

NASA Astrophysics Data System (ADS)

Fumagalli, P.; Borghini, G.; Rampone, E.; Poli, S.

2017-06-01

The crystallization of plagioclase-bearing assemblages in mantle rocks is witness of mantle exhumation at shallow depth. Previous experimental works on peridotites have found systematic compositional variations in coexisting minerals at decreasing pressure within the plagioclase stability field. In this experimental study we present new constraints on the stability of plagioclase as a function of different Na2O/CaO bulk ratios, and we present a new geobarometer for mantle rocks. Experiments have been performed in a single-stage piston cylinder at 5-10 kbar, 1050-1150 °C at nominally anhydrous conditions using seeded gels of peridotite compositions (Na2O/CaO = 0.08-0.13; X Cr = Cr/(Cr + Al) = 0.07-0.10) as starting materials. As expected, the increase of the bulk Na2O/CaO ratio extends the plagioclase stability to higher pressure; in the studied high-Na fertile lherzolite (HNa-FLZ), the plagioclase-spinel transition occurs at 1100 °C between 9 and 10 kbar; in a fertile lherzolite (FLZ) with Na2O/CaO = 0.08, it occurs between 8 and 9 kbar at 1100 °C. This study provides, together with previous experimental results, a consistent database, covering a wide range of P- T conditions (3-9 kbar, 1000-1150 °C) and variable bulk compositions to be used to define and calibrate a geobarometer for plagioclase-bearing mantle rocks. The pressure sensitive equilibrium: Mg_{2}SiO_{4}^Ol\\limits_{Forsterite} + CaAl_{2}Si_{2}O_{8}^{Pl\\limits_{Anorthite} = CaAl_{2}SiO_{6}^{Cpx}\\limits_{Ca-Tschermak} + Mg_{2}Si_{2}O_{6}^{Opx}\\limits_{Enstatite}, has been empirically calibrated by least squares regression analysis of experimental data combined with Monte Carlo simulation. The result of the fit gives the following equation: P=7.2( ± 2.9)+0.0078( ± 0.0021)T{{ }}+0.0022( ± 0.0001)T ln K, {R^2}=0.93, where P is expressed in kbar and T in kelvin. K is the equilibrium constant K = a CaTs × a en/ a an × a fo, where a CaTs, a en, a an and a fo are the activities of Ca-Tschermak in clinopyroxene, enstatite in orthopyroxene, anorthite in plagioclase and forsterite in olivine. The proposed geobarometer for plagioclase peridotites, coupled to detailed microstructural and mineral chemistry investigations, represents a valuable tool to track the exhumation of the lithospheric mantle at extensional environments.

Mantle Evolution Beneath The Colorado Palteau: Interpreta-tion of The Study of Mineral Concentrate From Kimberlite Pipe Kl-1 Colorado.

NASA Astrophysics Data System (ADS)

Ashchepkov, I.; Vladykin, N.; Mitchell, R.; Coopersmith, H.; Garanin, V.; Saprykin, A. I.; Khmelnikova, O. S.

Mineral grains and their intergrowth from the concentrate form the KL1- kimberlite pipe Colorado plateau was analyzed by EPMA and LAM ICP MS in Analytic Center of UIGGM. Garnets reveal nearly continuous trend of the compositions divided into 5 intervals. 1 cumulates from the crust and Sp facie mantle; 2. Gar-Sp lherzolites; 3- Gar- wehrlites, lherzolites and harzburgites; 4- Gar lherzolites and harzburgites; 4. Pyroxenites and Il peri-dotites . They reveal three trend of Ti decrease with the ris- ing Cr content. Those in the inter-growth with the pyroxenes are less in Tio2 as well as the pyroxenes. Discrete large Cpx grains are richer in Na, Al, Cr. TP conditions determined for the clinopyroxenes with Nimis- Taylor, 2001 thermobarometer and barometer Ashchepkov, 2001 reveal the heating from 35 to 40-42 mv/m2 in 30-50kbar interval. The spinels show two compositional intervals 64-50% Cr2O3 and 47-30%. The branch with the essential enrichment to 8% TiO2with the Cr decrease what also suppose the peridotite alteration due to rising of evolving Ti-rich melts. Two descend- ing crystallization lines for the ilmenites suggest the (polybaric) differentiation in two magmatic chambers. The Cr-rich ilmenites and most Cr-rich subcalcis garnets were found in the serpentinized ilmenite harzburgites that probably surround the most deep mag-matic chamber. The Ilm -Q (coesite) intergrowth suggests the deep differenti- ation. Several ilmenites contain up to 11%MnO. Trace elements determined for the clinopyroxenes suppose small decree melting possibly under influence of subducted- related melts having definite U peak and Ta-Nb minimums. Their reaction with peri- dotites with garnet dissolution according to AFC model decrease La/Ybn ration as well as the Pb* and U peak. Two stages of the Ti-rich melt percolations suggested to be accompanied the plum- re-lated melts influence on the peridotite of Wyoming craton keel which was followed with fur-ther followed by submelting of the subducted essentially eclogitic Na-Ti material. The de-formations assist the melt percolation at the final stage. Supported by RBEF grants 05-99-65688, 00-05-65288

Aluminide slurry coatings for protection of ferritic steel in molten nitrate corrosion for concentrated solar power technology

NASA Astrophysics Data System (ADS)

Audigié, Pauline; Bizien, Nicolas; Baráibar, Ignacio; Rodríguez, Sergio; Pastor, Ana; Hernández, Marta; Agüero, Alina

2017-06-01

Molten nitrates can be employed as heat storage fluids in solar concentration power plants. However molten nitrates are corrosive and if operating temperatures are raised to increase efficiencies, the corrosion rates will also increase. High temperature corrosion resistant coatings based on Al have demonstrated excellent results in other sectors such as gas turbines. Aluminide slurry coated and uncoated P92 steel specimens were exposed to the so called Solar Salt (industrial grade), a binary eutectic mixture of 60 % NaNO3 - 40 % KNO3, in air for 2000 hours at 550°C and 580°C in order to analyze their behavior as candidates to be used in future solar concentration power plants employing molten nitrates as heat transfer fluids. Coated ferritic steels constitute a lower cost technology than Ni based alloy. Two different coating morphologies resulting from two heat treatment performed at 700 and 1050°C after slurry application were tested. The coated systems exhibited excellent corrosion resistance at both temperatures, whereas uncoated P92 showed significant mass loss from the beginning of the test. The coatings showed very slow reaction with the molten Solar Salt. In contrast, uncoated P92 developed a stratified, unprotected Fe, Cr oxide with low adherence which shows oscillating Cr content as a function of coating depth. NaFeO2 was also found at the oxide surface as well as within the Fe, Cr oxide.

Comparative statistical analysis of chrome and vegetable tanning effluents and their effects on related soil.

PubMed

Tariq, Saadia R; Shah, Munir H; Shaheen, Nazia

2009-09-30

Two tanning units of Pakistan, namely, Kasur and Mian Channun were investigated with respect to the tanning processes (chrome and vegetable, respectively) and the effects of the tanning agents on the quality of soil in vicinity of tanneries were evaluated. The effluent and soil samples from 16 tanneries each of Kasur and Mian Channun were collected. The levels of selected metals (Na, K, Ca, Mg, Fe, Cr, Mn, Co, Cd, Ni, Pb and Zn) were determined by using flame atomic absorption spectrophotometer under optimum analytical conditions. The data thus obtained were subjected to univariate and multivariate statistical analyses. Most of the metals exhibited considerably higher concentrations in the effluents and soils of Kasur compared with those of Mian Channun. It was observed that the soil of Kasur was highly contaminated by Na, K, Ca and Mg emanating from various processes of leather manufacture. Furthermore, the levels of Cr were also present at much enhanced levels than its background concentration due to the adoption of chrome tanning. The levels of Cr determined in soil samples collected from the vicinity of Mian Channun tanneries were almost comparable to the background levels. The soil of this city was found to have contaminated only by the metals originating from pre-tanning processes. The apportionment of selected metals in the effluent and soil samples was determined by a multivariate cluster analysis, which revealed significant differences in chrome and vegetable tanning processes.

Signature of Metallic ion in the upper atmosphere of Mars following the passage of comet C/2013 A1 (Siding Spring)

NASA Astrophysics Data System (ADS)

Benna, M.; Grebowsky, J. M.; Mahaffy, P. R.; Plane, J. M. C.; Yelle, R. V.; Jakosky, B. M.

2017-09-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission made the first in situ detection of metal ions in the upper atmosphere of Mars. These ions result from the ablation of dust particles from comet Siding Spring. This detection was carried out by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the MAVEN spacecraft. Metal ions of Na, Mg, Al, K, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and possibly of Si, and Ca, were identified in the ion spectra collected at altitudes of 185 km. The measurements revealed that Na ion was the most abundant species, and that the remaining metals were depleted with respect to the CI (type 1 carbonaceous Chondrites) abundance of Na ion.

Strain-Engineered Multiferroicity in Pnma NaMnF_{3} Fluoroperovskite.

PubMed

Garcia-Castro, A C; Romero, A H; Bousquet, E

2016-03-18

In this study we show from first principles calculations the possibility to induce multiferroic and magnetoelectric functional properties in the Pnma NaMnF_{3} fluoroperovskite by means of epitaxial strain engineering. Surprisingly, we found a very strong nonlinear polarization-strain coupling that drives an atypical amplification of the ferroelectric polarization for either compression or expansion of the cell. This property is associated with a noncollinear antiferromagnetic ordering, which induces a weak ferromagnetism phase and makes the strained NaMnF_{3} fluoroperovskite multiferroic. The magnetoelectric response was calculated and it was found to be composed of linear and nonlinear components with amplitudes similar to the ones of Cr_{2}O_{3}. These findings show that it is possible to move the fluoride family toward functional applications with unique responses.

Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications

DOE PAGES

Rosenberg, M. J.; Séguin, F. H.; Waugh, C. J.; ...

2014-04-14

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ~0.5–8 MeV protons. When the fluence of incident particles becomes too high, the overlap of particle tracks leads to under-counting at typical processing conditions (5h etch in 6N NaOH at 80°C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detectionmore » of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 ×10 6 cm -2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ~50, increasing the operating yield upper limit by a comparable amount.« less

Extraction of anionic dye from aqueous solutions by emulsion liquid membrane.

PubMed

Dâas, Attef; Hamdaoui, Oualid

2010-06-15

In this work, the extraction of Congo red (CR), an anionic disazo direct dye, from aqueous solutions by emulsion liquid membrane (ELM) was investigated. The important operational parameters governing emulsion stability and extraction behavior of dye were studied. The extraction of CR was influenced by a number of variables such as surfactant concentration, stirring speed, acid concentration in the feed solution and volume ratios of internal phase to organic phase and of emulsion to feed solution. Under most favorable conditions, practically all the CR molecules present in the feed phase were extracted even in the presence of salt (NaCl). At the optimum experimental conditions, total removal of antharaquinonic dye Acid Blue 25 was attained after only 10 min. Influence of sodium carbonate concentration as internal receiving phase on the stripping efficiency of CR was examined. The best sodium carbonate concentration in the internal phase that conducted to excellent stripping efficiency (>99%) and emulsion stability was 0.1N. The membrane recovery was total and the permeation of CR was not decreased up to seven runs. ELM process is a promising alternative to conventional methods and should increase awareness of the potential for recovery of anionic dyes. Copyright 2010 Elsevier B.V. All rights reserved.

Mitigating Localized Corrosion Using Thermally Sprayed Aluminum (TSA) Coatings on Welded 25% Cr Superduplex Stainless Steel

NASA Astrophysics Data System (ADS)

Paul, S.; Lu, Q.; Harvey, M. D. F.

2015-04-01

Thermally sprayed aluminum (TSA) coating has been increasingly used for the protection of carbon steel offshore structures, topside equipment, and flowlines/pipelines exposed to both marine atmospheres and seawater immersion conditions. In this paper, the effectiveness of TSA coatings in preventing localized corrosion, such as pitting and crevice corrosion of 25% Cr superduplex stainless steel (SDSS) in subsea applications, has been investigated. Welded 25% Cr SDSS (coated and uncoated) with and without defects, and surfaces coated with epoxy paint were also examined. Pitting and crevice corrosion tests, on welded 25% Cr SDSS specimens with and without TSA/epoxy coatings, were conducted in recirculated, aerated, and synthetic seawater at 90 °C for 90 days. The tests were carried out at both the free corrosion potentials and an applied cathodic potential of -1100 mV saturated calomel electrode. The acidity (pH) of the test solution was monitored daily and adjusted to between pH 7.5 and 8.1, using dilute HCl solution or dilute NaOH, depending on the pH of the solution measured during the test. The test results demonstrated that TSA prevented pitting and crevice corrosion of 25% Cr SDSS in artificial seawater at 90 °C, even when 10-mm-diameter coating defect exposing the underlying steel was present.

Impact of corrosion test container material in molten fluorides

DOE PAGES

Olson, Luke C.; Fuentes, Roderick E.; Martinez-Rodriguez, Michael J.; ...

2015-10-15

The effects of crucible material choice on alloy corrosion rates in immersion tests in molten LiF–NaF–KF (46.5–11.5-42 mol. %) salt held at 850 °C for 500 hrs are described. Four crucible materials were studied. Molten salt exposures of Incoloy-800H in graphite, Ni, Incoloy-800H, and pyrolytic boron nitride (PyBN) crucibles all led to weight-loss in the Incoloy-800H coupons. Alloy weight loss was ~30 times higher in the graphite and Ni crucibles in comparison to the Incoloy-800H and PyBN crucibles. It is hypothesized galvanic coupling between the alloy coupons and crucible materials contributed to the higher corrosion rates. Alloy salt immersion inmore » graphite and Ni crucibles had similar weight-loss hypothesized to occur due to the rate limiting out diffusion of Cr in the alloys to the surface where it reacts with and dissolves into the molten salt, followed by the reduction of Cr from solution at the molten salt and graphite/Ni interfaces. As a result, both the graphite and the Ni crucibles provided sinks for the Cr, in the formation of a Ni–Cr alloy in the case of the Ni crucible, and Cr carbide in the case of the graphite crucible.« less

The Influence of Plasma-Based Nitriding and Oxidizing Treatments on the Mechanical and Corrosion Properties of CoCrMo Biomedical Alloy

NASA Astrophysics Data System (ADS)

Noli, Fotini; Pichon, Luc; Öztürk, Orhan

2018-04-01

Plasma-based nitriding and/or oxidizing treatments were applied to CoCrMo alloy to improve its surface mechanical properties and corrosion resistance for biomedical applications. Three treatments were performed. A set of CoCrMo samples has been subjected to nitriding at moderate temperatures ( 400 °C). A second set of CoCrMo samples was oxidized at 395 °C in pure O2. The last set of CoCrMo samples was nitrided and subsequently oxidized under the experimental conditions of previous sets (double treatment). The microstructure and morphology of the layers formed on the CoCrMo alloy were investigated by X-ray diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy. In addition, nitrogen and oxygen profiles were determined by Glow Discharge Optical Emission Spectroscopy, Rutherford Backscattering Spectroscopy, Energy-Dispersive X-ray, and Nuclear Reaction Analysis. Significant improvement of the Vickers hardness of the CoCrMo samples after plasma nitriding was observed due to the supersaturated nitrogen solution and the formation of an expanded FCC γ N phase and CrN precipitates. In the case of the oxidized samples, Vickers hardness improvement was minimal. The corrosion behavior of the samples was investigated in simulated body fluid (0.9 pct NaCl solution at 37 °C) using electrochemical techniques (potentiodynamic polarization and cyclic voltammetry). The concentration of metal ions released from the CoCrMo surfaces was determined by Instrumental Neutron Activation Analysis. The experimental results clearly indicate that the CoCrMo surface subjected to the double surface treatment consisting in plasma nitriding and plasma oxidizing exhibited lower deterioration and better resistance to corrosion compared to the nitrided, oxidized, and untreated samples. This enhancement is believed to be due to the formation of a thicker and more stable layer.

Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro

PubMed Central

Li, Jing; Cao, Wei; Lv, Xiao-xing; Jiang, Li; Li, Yue-jun; Li, Wang-zhou; Chen, Shao-zong; Li, Xue-yong

2013-01-01

Aim: To examine the changes in electrolyte concentrations after addition of zeolite-based hemostat QuikClot in blood and the effects of zeolite on blood coagulation in vitro. Methods: Fresh blood was taken from healthy adult volunteers and sheep, and the electrolyte concentrations in blood were measured using a blood electrolyte analyzer. Zeolite Saline Solution (ZSS) was prepared by addition of 2 g zeolite to 0.9% NaCl solution (4, 8, or 16 mL). The electrolytes in ZSS were measured using inductively coupled plasma atomic emission spectroscopy. The prothrombin time (PT) and activated partial thromboplastin time (APTT) of blood were measured using the test tube method. The activated clotting time (ACT) and clotting rate (CR) of blood were measured with Sonoclot Coagulation and Platelet Function Analyzer. Results: Addition of zeolite (50 and 100 mg) in 2 mL human blood significantly increased Ca2+ concentration, while Na+ and K+ concentrations were significantly decreased. Addition of zeolite (50 and 100 mg) in 0.9% NaCl solution (2 mL) caused similar changes in Ca2+ and Na+ concentrations. Si4+ (0.2434 g/L) and Al3+ (0.2575 g/L) were detected in ZSS (2 g/8 mL). Addition of ZSS in sheep blood shortened APTT in a concentration dependent manner, without changing PT. ZSS or aqueous solution of CaCl2 that contained Ca2+ concentration identical to that of ZSS significantly shortened ACT in human blood without significantly changing CR, and the effect of ZSS on ACT was not significantly different from that of CaCl2. Conclusion: Zeolite releases Ca2+ into blood, thus accelerating the intrinsic pathway of blood coagulation and shortening the clot formation time. PMID:23334236

Trace metals and macroelements in mussels from Chinese coastal waters: National spatial patterns and normalization.

PubMed

Lu, Guang-Yuan; Wang, Wen-Xiong

2018-06-01

Metal contamination is one of the most ubiquitous and complex problems in the Chinese coastal environment. To explore the large-scale spatial patterns of bioavailable metals, we sampled three major mussels, including 784 blue mussels (Mytilus edulis Linnaeus, 1758) of 14 sites, 224 hard-shelled mussels (Mytilus unguiculatus Valenciennes, 1858) of 4 sites, and 392 green mussels (Perna viridis (Linnaeus, 1758)) of 7 sites, ranging from temperate to tropical coastlines of China, during August and September 2015. The concentrations of macroelements (Na, K, Ca, Mg, and P) and toxic trace metals (Ag, Cd, Cr, Cu, Ni, Pb, Ti, and Zn) in the mussel's whole soft tissues were determined. Among the four Chinese coastal basins, Cd, Ti and Cr in the mussel tissues were the highest at Bohai Sea (BS) and Yellow Sea (YS), and Cu, Ni, Pb and Ag in the mussel tissues were the highest at East China Sea (ECS) and South China Sea (SCS). Zinc concentrations in mussels from YS were significantly higher than those from the other regions. Given the variability of environmental conditions such as salinity and nutrients, we further normalized the measured tissue metal concentrations with tissue Na and P levels. After Na normalization as the salinity proxy, the variability of Cd, Cu, Zn, Ag, and Ni was reduced. Trace elements accumulation in the mussel tissues was significantly related to both macroelements (Na or P) and body dry weight. The present study demonstrated that nonlinear optimization of different elements was necessary in assessing metal bioaccumulation patterns in marine mussels at a large spatial scale. Copyright © 2018 Elsevier B.V. All rights reserved.

Alterations in perivascular innervation function in mesenteric arteries from offspring of diabetic rats

PubMed Central

de Queiroz, D B; Sastre, E; Caracuel, L; Callejo, M; Xavier, F E; Blanco-Rivero, J; Balfagón, G

2015-01-01

Background and Purpose We have reported that exposure to a diabetic intrauterine environment during pregnancy increases blood pressure in adult offspring, but the mechanisms involved are not completely understood. This study was designed to analyse a possible role of perivascular sympathetic and nitrergic innervation in the superior mesenteric artery (SMA) in this effect. Experimental Approach Diabetes was induced in pregnant Wistar rats by a single injection of streptozotocin. Endothelium-denuded vascular rings from the offspring of control (O-CR) and diabetic rats (O-DR) were used. Vasomotor responses to electrical field stimulation (EFS), NA and the NO donor DEA-NO were studied. The expressions of neuronal NOS (nNOS) and phospho-nNOS (P-nNOS) and release of NA, ATP and NO were determined. Sympathetic and nitrergic nerve densities were analysed by immunofluorescence. Key Results Blood pressure was higher in O-DR animals. EFS-induced vasoconstriction was greater in O-DR animals. This response was decreased by phentolamine more in O-DR animals than their controls. L-NAME increased EFS-induced vasoconstriction more strongly in O-DR than in O-CR segments. Vasomotor responses to NA or DEA-NO were not modified. NA, ATP and NO release was increased in segments from O-DR. nNOS expression was not modified, whereas P-nNOS expression was increased in O-DR. Sympathetic and nitrergic nerve densities were similar in both experimental groups. Conclusions and Implications The activity of sympathetic and nitrergic innervation is increased in SMA from O-DR animals. The net effect is an increase in EFS-induced contractions in these animals. These effects may contribute to the increased blood pressure observed in the offspring of diabetic rats. PMID:26177571

Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro.

PubMed

Li, Jing; Cao, Wei; Lv, Xiao-xing; Jiang, Li; Li, Yue-jun; Li, Wang-zhou; Chen, Shao-zong; Li, Xue-yong

2013-03-01

To examine the changes in electrolyte concentrations after addition of zeolite-based hemostat QuikClot in blood and the effects of zeolite on blood coagulation in vitro. Fresh blood was taken from healthy adult volunteers and sheep, and the electrolyte concentrations in blood were measured using a blood electrolyte analyzer. Zeolite Saline Solution (ZSS) was prepared by addition of 2 g zeolite to 0.9% NaCl solution (4, 8, or 16 mL). The electrolytes in ZSS were measured using inductively coupled plasma atomic emission spectroscopy. The prothrombin time (PT) and activated partial thromboplastin time (APTT) of blood were measured using the test tube method. The activated clotting time (ACT) and clotting rate (CR) of blood were measured with Sonoclot Coagulation and Platelet Function Analyzer. Addition of zeolite (50 and 100 mg) in 2 mL human blood significantly increased Ca(2+) concentration, while Na(+) and K(+) concentrations were significantly decreased. Addition of zeolite (50 and 100 mg) in 0.9% NaCl solution (2 mL) caused similar changes in Ca(2+) and Na(+) concentrations. Si(4+) (0.2434 g/L) and Al(3+) (0.2575 g/L) were detected in ZSS (2 g/8 mL). Addition of ZSS in sheep blood shortened APTT in a concentration dependent manner, without changing PT. ZSS or aqueous solution of CaCl2 that contained Ca(2+) concentration identical to that of ZSS significantly shortened ACT in human blood without significantly changing CR, and the effect of ZSS on ACT was not significantly different from that of CaCl2. Zeolite releases Ca(2+) into blood, thus accelerating the intrinsic pathway of blood coagulation and shortening the clot formation time.

Structural relatedness of three ion-transport adenosine triphosphatases around their active sites of phosphorylation.

PubMed

Walderhaug, M O; Post, R L; Saccomani, G; Leonard, R T; Briskin, D P

1985-03-25

Three membrane-bound adenosine triphosphatases were investigated for homology in the sequence of four amino acids about the active site of phosphorylation. The ATPases were as follows: sodium-potassium-dependent ATPase from dog kidney, Na,K-ATPase; hydrogen-potassium-dependent ATPase from hog gastric mucosa, H,K-ATPase, an ATPase similar to Na,K-ATPase; and an ATPase activity in the plasma membrane of corn, Zea mays, roots (CR-ATPase), a higher plant ATPase. A membrane preparation containing an ATPase of Acholeplasma laidlawii, a prokaryote, (AL) was also investigated. For most of the experiments, the preparations were phosphorylated from [gamma-32P]ATP, denatured in acid, and subjected to proteolytic digestion. Radioactive phosphopeptides were separated by high voltage paper electrophoresis and characterized by sensitivity to chemical reagents. In gastric H,K-ATPase, the aspartate residue at the active site was determined directly by labeling with [3H]borohydride. A common sequence around the active site was found for Na,K-ATPase, H,K-ATPase, and CR-ATPase. This sequence, -Cys-(Ser/Thr)-Asp(P)-Lys-, is similar to that in the calcium ion-transport ATPase of sarcoplasmic reticulum. The AL membrane preparation showed an acylphosphate that turned over rapidly after a chase of labeled membranes with unlabeled ATP. The corresponding sequence was different from that of the three ATPases. An acylphosphate was on two polypeptides with molecular weights of about 80,000 and 60,000; these appear not to correspond to subunits of a Na+-stimulated ATPase in this organism (Lewis, R. N. A. H., and McElhaney, R. N. (1983) Biochim. Biophys. Acta 735, 113-122).

A Study on Characteristics of Atmospheric Heavy Metals in Subway Station

PubMed Central

Kim, Chun-Huem; Yoo, Dong-Chul; Kwon, Young-Min; Han, Woong-Soo; Kim, Gi-Sun; Park, Mi-Jung; Kim, Young Soon

2010-01-01

In this study, we investigated the atmospheric heavy metal concentrations in the particulate matter inside the subway stations of Seoul. In particular, we examined the correlation between the heavy metals and studied the effect of the heavy metals on cell proliferation. In six selected subway stations in Seoul, particulate matter was captured at the platforms and 11 types of heavy metals were analyzed. The results showed that the mean concentration of iron was the highest out of the heavy metals in particulate matter, followed by copper, potassium, calcium, zinc, nickel, sodium, manganese, magnesium, chromium and cadmium in that order. The correlation analysis showed that the correlations between the heavy metals was highest in the following order: (Cu vs Zn) , (Ca vs Na) , (Ca vs Mn) , (Ni vs Cr) , (Na vs Mn) , (Cr vs Cd) , (Zn vs Cd) , (Cu vs Cd) , (Ni vs Cd) , (Cu vs Ni) , (K vs Zn) , (Cu vs K) , (Cu vs Cr) , (K vs Cd) , (Zn vs Cr) , (K vs Ni) , (Zn vs Ni) , (K vs Cr) , and (Fe vs Cu) . The correlation coefficient between zinc and copper was 0.937, indicating the highest correlation. Copper, zinc, nickel, chromium and cadmium, which are generated from artificial sources in general, showed correlations with many of the other metals and the correlation coefficients were also relatively high. The effect of the heavy metals on cell proliferation was also investigated in this study. Cultured cell was exposed to 10 mg/l or 100 mg/l of iron, copper, calcium, zinc, nickel, manganese, magnesium, chromium and cadmium for 24 hours. The cell proliferation in all the heavy metal-treated groups was not inhibited at 10 mg/l of the heavy metal concentration. The only exception to this was with the cadmium-treated group which showed a strong cell proliferation inhibition. This study provides the fundamental data for the understanding of simultaneous heavy metal exposure tendency at the time of particulate matter exposure in subway stations and the identification of heavy metal sources. Moreover, this study can be used as the fundamental data for the cell toxicity study of the subway-oriented heavy metal-containing particulate matter. PMID:24278519

Trivalent chromium solubility and its influence on quantification of hexavalent chromium in ambient particulate matter using EPA method 6800.

PubMed

Huang, Lihui; Yu, Chang Ho; Hopke, Philip K; Shin, Jin Young; Fan, Zhihua

2014-12-01

Measurement of carcinogenic Cr(VI) in ambient PM is challenging due to potential errors associated with conversion between Cr (VI) (a carcinogen) and Cr(III) (an essential nutrient). Cr(III) conversion is a particular concern due to its > 80% atomic abundance in total Cr. US. Environmental Protection Agency (EPA) method 6800 that uses water-soluble isotope spikes can be used to correct the interconversion. However, whether the enriched Cr(III) isotope spikes can adequately mimic the Cr(III) species originally in ambient PM is unknown. This study examined the water solubility of Cr(III) in ambient PM and discussed its influence on Cr(VI) measurement. Ambient PM10 samples were collected on Teflon filters at four sites in New Jersey that may have different Cr emission sources. The samples were ultrasonically extracted with 5 mL DI-H2O (pH 5.7) at room temperature for 40 min, and then analyzed by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS). Cr(III) was below detection limit (0.06 ng/m3) for all samples, suggesting water-soluble Cr(III) species, such as CrCl3, Cr(NO3)3, and amorphous Cr(OH)3, in the ambient PM were negligible. Therefore, the enriched 50Cr(III) isotope spike (in the form of Cr(NO3)3) could not mimic the original ambient Cr(III). Only the conversion of 53Cr(VI) (in the form of K2CrO4) was taken into account when correcting the interconversion. We then used NaHCO3-pretreated MCE filters (prespiked with enriched isotope species) to measure Cr(VI) in the ambient PM10. The samples were ultrasonically extracted at 60 C pH 9 solutions for 40 min followed by IC-ICPMS analysis. Due to the correction of Cr(VI) reduction, the Cr(VI) concentrations determined by EPA method 6800, 0.26 ± 0.16 (summer) and 0.16 ± 0.11(winter) ng/m3 (n = 64), were significantly greater than those by the external standard curve, 0.21 ± 0.17 (summer) and 0.10 ± 0.07 (winter) ng/m3 (n = 56) (p < 0.01, Student's t-test). Our study revealed that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species in ambient PM. Implications: Accurate measurement of carcinogenic Cr(VI) in ambient PM is challenging due to conversion between Cr(VI) (a human carcinogen) and Cr(III) (a human essential nutrient). The conversion of CR(III) is of particular concern due to its dominant presence in total Cr (>80%). This study examined the water solubility of Cr(III) in ambient PM that was collected at four locations in New Jersey. Then we discussed the influence of Cr(III) solubility on the application of EPA method 6800, which utilizes enriched isotope spikes to correct the interconversion. Our results suggested that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species.

Carboxymethylhydroxyethyl cellulose in drilling, workover and completion fluids

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

Sauber, C. A.

Certain carboxymethylhydroxyethyl cellulose (CMHEC) solutions in waters of various salinities are gelled by dichromate ion at a pH of about 5 or less, thus forming a drilling fluid or component thereof. In an embodiment a CMHEC water solution is gelled using an alkali metal dichromate, e.g., Na2Cr2O7.2H2O.

Characteristics of HY-180 and Ti-100 for Welded High Strength Structures

DTIC Science & Technology

1974-12-01

materials in welded structures are reported. The 10Ni-8Co-2Cr-lMo steel arid the Ti- 6Al -2Cb-lTa-0. 8Mo titanium alloy were selected as candidate...only li- 6Al -iCb-na-0.»Mo (Ti-6-2-1-1) and’Ii- 6Al - 4V are competitive with 10Ni-8Co-2Cr-lMo steel on a strength-weight basis, while possessing ade...Ti- 6Al -2Cb-lTa-0. 8Mo has better toughness in plate form, based upon dynamic tear properties. There- fore the Ti- 6Al -2Cb-lTa-0.8Mo titanium alloy

Equilibrium isotherms, kinetics, and thermodynamics studies for congo red adsorption using calcium alginate beads impregnated with nano-goethite.

PubMed

Munagapati, Venkata Subbaiah; Kim, Dong-Su

2017-07-01

The present study is concerned with the batch adsorption of congo red (CR) from an aqueous solution using calcium alginate beads impregnated with nano-goethite (CABI nano-goethite) as an adsorbent. The optimum conditions for CR removal were determined by studying operational variables viz. pH, adsorbent dose, contact time, initial dye ion concentration and temperature. The CABI nano-goethite was characterized by Fourier transform infrared spectroscopy (FTIR), X- ray diffraction (XRD) and Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis. The CR sorption data onto CABI nano-goethite were described using Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The results show that the best fit was achieved with the Langmuir isotherm model. The maximum adsorption capacity (181.1mg/g) of CR was occurred at pH 3.0. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Desorption experiments were carried out to explore the feasibility of regenerating the adsorbent and the adsorbed CR from CABI nano-goethite. The best desorbing agent was 0.1M NaOH with an efficiency of 94% recovery. The thermodynamic parameters ΔG°, ΔH°, and ΔS° for the CR adsorption were determined by using adsorption capacities at five different temperatures (293, 303, 313, 323 and 303K). Results show that the adsorption process was endothermic and favoured at high temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

Radiation-induced graft polymerization for the preparation of a highly efficient UHMWPE fibrous adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Gao, Qianhong; Hua, Jiangtao; Li, Rong; Xing, Zhe; Pang, Lijuan; Zhang, Mingxing; Xu, Lu; Wu, Guozhong

2017-01-01

A novel fibrous adsorbent containing amine and quaternary ammonium groups was prepared by radiation-induced graft of glycidyl methacrylate (GMA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber and further modifying with triethylenetetramine (TETA) and glycidyl trimethylammonium chloride (GTA). The ATR-IR spectra and SEM observation demonstrated that amine and quaternary ammonium groups were immobilized onto the surface of UHMWPE fiber. The principal factors affecting the adsorption of Cr(VI) ions have been investigated including pH of the aqueous solution, contact time, temperature and coexisting anions. This novel fibrous adsorbent could effectively adsorb Cr(VI) in the range of pH 1-9, and the maximum adsorption capacity reached 295 mg/g at pH 3 and 25 °C based on the Langmuir isotherm. It was found that adsorption equilibrium could be achieved within 2 h for initial Cr(VI) of 100 mg/L, following the pseudo-second order model. The effect of coexisting anions (including SO42-, H2PO4-, NO3-and Cl-) on the uptake of Cr(VI) was investigated in detail. Additionally, the adsorption saturated fiber could be regenerated by soaking in 0.5 mol/L NaOH solution, and the adsorption performance of this adsorbent could be maintained at 90% after eight cycles of adsorption-desorption. ATR-IR and XPS analysis revealed that Cr(VI) ions were adsorbed on the fiber adsorbent through ion exchange mechanism.

Chemical and mineralogical characterization of chromite ore processing residue from two recent Indian disposal sites.

PubMed

Matern, Katrin; Kletti, Holger; Mansfeldt, Tim

2016-07-01

Chromite ore processing residue (COPR) is a hazardous waste. Nevertheless, deposition of COPR in uncontrolled surface landfills is still common practice in some countries. Whereas old (between at least 40 and 180 years) COPR from the temperate zone has been intensively investigated, information on COPR in other regions is restricted. Relatively young (<25 years) COPR samples obtained from two abandoned landfill sites in India were investigated by a modified total microwave digestion method, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM) in order to determine their chemical and mineralogical nature. By the use of microwave digestion with acid mixtures of HNO3, H3PO4, and HBF4 (5:3:2 vol), COPR was completely dissolved and element contents similar to those obtained by X-ray fluorescence were found. Total Cr contents of the two COPR accounted for 81 and 74 g kg(-1), of which 20 and 13% were present in the carcinogenic hexavalent form (CrVI). Apart from the common major mineral phases present in COPR reported earlier, a further Cr host mineral, grimaldiite [CrO(OH)], could be identified by XRPD and SEM. Additionally, well soluble Na2CrO4 was present. Improving the effectiveness of chromite ore processing and preventing the migration of Cr(VI) into water bodies are the main challenges when dealing with these COPR. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Comparative Study of the Corrosion Behavior of Three Stainless Steels in an Eutectic (Li,Na,K)2CO3 Melt with and without (Na,K)Cl Additives at 973K in Air

NASA Astrophysics Data System (ADS)

Zeng, C. L.; Liu, Y.

2011-04-01

The ternary carbonate eutectic mixture of Li2CO3, K2CO3 and Na2CO3 as a heat transfer and storage medium has excellent thermophysical properties, but with high viscidity as compared with some other inorganic salts such as chlorides and nitrates. The addition of chlorides or fluorides to molten carbonates may improve their fluidity, but possibly making the melt become more corrosive. In this study, the corrosion behavior of type 304, 310 and 316 stainless steels in an eutectic (Li,Na,K)2CO3 melt with and without an eutectic mixture of NaCl and KCl at 973K in air have been examined. The experimental results indicated that 310 steel shows a much better corrosion resistance in molten carbonates than both 304 and 316 steels, due to the formation of a continuous LiCrO2 scale. The addition of chlorides to carbonates melt accelerated the corrosion of the steels, especially 310 steel, producing scales with more porosity.

Generation and detection of metal ions and volatile organic compounds (VOCs) emissions from the pretreatment processes for recycling spent lithium-ion batteries.

PubMed

Li, Jia; Wang, Guangxu; Xu, Zhenming

2016-06-01

The recycling of spent lithium-ion batteries brings benefits to both economic and environmental terms, but it can also lead to contaminants in a workshop environment. This study focused on metals, non-metals and volatile organic compounds generated by the discharging and dismantling pretreatment processes which are prerequisite for recycling spent lithium-ion batteries. After discharging in NaCl solution, metal contents in supernate and concentrated liquor were detected. Among results of condition #2, #3, #4 and #5, supernate and concentrated liquor contain high levels of Na, Al, Fe; middle levels of Co, Li, Cu, Ca, Zn; and low levels of Mn, Sn, Cr, Zn, Ba, K, Mg, V. The Hg, Ag, Cr and V are not detected in any of the analyzed supernate. 10wt% NaCl solution was a better discharging condition for high discharge efficiency, less possible harm to environment. To collect the gas released from dismantled LIB belts, a set of gas collecting system devices was designed independently. Two predominant organic vapour compounds were dimethyl carbonate (4.298mgh(-1)) and tert-amylbenzene (0.749mgh(-1)) from one dismantled battery cell. To make sure the concentrations of dimethyl carbonate under recommended industrial exposure limit (REL) of 100mgL(-1), for a workshop on dismantling capacity of 1000kg spent LIBs, the minimum flow rate of ventilating pump should be 235.16m(3)h(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Residual waste from Hanford tanks 241-C-203 and 241-C-204. 1. Solids characterization.

PubMed

Krupka, Kenneth M; Schaef, Herbert T; Arey, Bruce W; Heald, Steve M; Deutsch, William I; Lindberg, Michael J; Cantrell, Kirk J

2006-06-15

Bulk X-ray diffraction (XRD), synchrotron X-ray microdiffraction (microXRD), and scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM/EDS) were used to characterize solids in residual sludge from single-shell underground waste tanks C-203 and C-204 at the U.S. Department of Energy's Hanford Site in southeastern Washington state. Cejkaite [Na4(UO2)(CO3)3] was the dominant crystalline phase in the C-203 and C-204 sludges. This is one of the few occurrences of cejkaite reported in the literature and may be the first documented occurrence of this phase in radioactive wastes from DOE sites. Characterization of residual solids from water leach and selective extraction tests indicates that cejkaite has a high solubility and a rapid rate of dissolution in water at ambient temperature and that these sludges may also contain poorly crystalline Na2U207 [or clarkeite Na[(UO2)O(OH)](H2O)0-1] as well as nitratine (soda niter, NaNO3), goethite [alpha-FeO(OH)], and maghemite (gamma-Fe2O3). Results of the SEM/EDS analyses indicate that the C-204 sludge also contains a solid that lacks crystalline form and is composed of Na, Al, P, O, and possibly C. Other identified solids include Fe oxides that often also contain Cr and Ni and occur as individual particles, coatings on particles, and botryoidal aggregates; a porous-looking material (or an aggregate of submicrometer particles) that typically contain Al, Cr, Fe, Na, Ni, Si, U, P, O, and C; Si oxide (probably quartz); and Na-Al silicate(s). The latter two solids probably represent minerals from the Hanford sediment, which were introduced into the tank during prior sampling campaigns or other tank operation activities. The surfaces of some Fe-oxide particles in residual solids from the water leach and selective extraction tests appear to have preferential dissolution cavities. If these Fe oxides contain contaminants of concern, then the release of these contaminants into infiltrating water would be limited by the dissolution rates of these Fe oxides, which in general have lowto very low solubilities and slow dissolution rates at near neutral to basic pH values under oxic conditions.

Strain-Engineered Multiferroicity in P n m a NaMnF3 Fluoroperovskite

NASA Astrophysics Data System (ADS)

Garcia-Castro, A. C.; Romero, A. H.; Bousquet, E.

2016-03-01

In this study we show from first principles calculations the possibility to induce multiferroic and magnetoelectric functional properties in the P n m a NaMnF3 fluoroperovskite by means of epitaxial strain engineering. Surprisingly, we found a very strong nonlinear polarization-strain coupling that drives an atypical amplification of the ferroelectric polarization for either compression or expansion of the cell. This property is associated with a noncollinear antiferromagnetic ordering, which induces a weak ferromagnetism phase and makes the strained NaMnF3 fluoroperovskite multiferroic. The magnetoelectric response was calculated and it was found to be composed of linear and nonlinear components with amplitudes similar to the ones of Cr2O3. These findings show that it is possible to move the fluoride family toward functional applications with unique responses.

Removal of Cd(II), Pb(II) and Cr(III) from water using modified residues of Anacardium occidentale L.

NASA Astrophysics Data System (ADS)

Coelho, Gustavo Ferreira; Gonçalves, Affonso Celso; Schwantes, Daniel; Rodríguez, Esperanza Álvarez; Tarley, César Ricardo Teixeira; Dragunski, Douglas; Conradi Junior, Élio

2018-06-01

The pollution of water has been one of the greatest problems faced by the modern society, due to industrialization and urban growth. Rivers, lakes and seas have been continually suffering from the rising concentration of various pollutants, especially toxic elements. This study aimed to evaluate the use of cashew nut shell ( Anacardium occidentale) (CNS), after chemical modification with H2O2, H2SO4 and NaOH, as an new and renewable adsorbent material, for the removal of metals Cd2+, Pb2+ and Cr3+ in aqueous medium. The adsorbents were characterized by its chemical constitution, structure, infrared spectroscopy, morphology, by means of scanning electron microscopy, determination of the point of zero charge, thermogravimetrical analysis and porosimetry assessments. Tests were conducted to determine the optimal conditions (pH vs. adsorbent mass) for adsorption, by means of multivariate analysis using a central composite design. The adsorption kinetics was evaluated by models of pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion, while adsorption isotherms were linearized by Langmuir, Freundlich and Dubinin-Radushkevich. The effect of initial concentration, temperature and desorption was also performed. The adsorbents exhibited irregular, spongy and heterogeneous structure. FTIR analysis confirms the presence of hydroxyl, aliphatic, phenolic and carboxylic acid groups, which are favorable adsorption characteristics. The pHPZC of adsorbent is 4.35, 2.50 e 6.92, respectively, for CNS H2O2, H2SO4 and NaOH. The optimum adsorption conditions were as follows: pH 5.0; relation of adsorbent mass/volume of water: 4 g L-1; 40 min of contact time for reaching the equilibration. Results suggest the predominance of chemisorption of Cd2+ and Cr3+. Most of biosorbents exhibited good fit by Langmuir and Freundlich, suggesting the occurrence of adsorption on mono- and multilayers. The adsorbents of cashew nut shell exhibited high removal efficiency of Cd, Pb and Cr from waters.

The Corrosion Behavior of Stainless Steel 316L in Novel Quaternary Eutectic Molten Salt System

NASA Astrophysics Data System (ADS)

Wang, Tao; Mantha, Divakar; Reddy, Ramana G.

2017-03-01

In this article, the corrosion behavior of stainless steel 316L in a low melting point novel LiNO3-NaNO3-KNO3-NaNO2 eutectic salt mixture was investigated at 695 K which is considered as thermally stable temperature using electrochemical and isothermal dipping methods. The passive region in the anodic polarization curve indicates the formation of protective oxides layer on the sample surface. After isothermal dipping corrosion experiments, samples were analyzed using SEM and XRD to determine the topography, corrosion products, and scale growth mechanisms. It was found that after long-term immersion in the LiNO3-NaNO3-KNO3-NaNO2 molten salt, LiFeO2, LiFe5O8, Fe3O4, (Fe, Cr)3O4 and (Fe, Ni)3O4 oxides were formed. Among these corrosion products, LiFeO2 formed a dense and protective layer which prevents the SS 316L from severe corrosion.

Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

NASA Astrophysics Data System (ADS)

Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

2017-03-01

The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating < the stainless steel with Al-Si coating < the stainless steel without any coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace.

PubMed

Stanislawska, Magdalena; Janasik, Beata; Wasowicz, Wojciech

2013-12-15

The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 μm, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

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.

Influence of Oxidation Treatments and Surface Finishing on the Electrochemical Behavior of Ni-20Cr HVOF Coatings

NASA Astrophysics Data System (ADS)

Ruiz-Luna, H.; Porcayo-Calderon, J.; Alvarado-Orozco, J. M.; Mora-García, A. G.; Martinez-Gomez, L.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

2017-12-01

The low-temperature electrochemical behavior of HVOF Ni-20Cr coatings was assessed. The coatings were evaluated in different conditions including as-sprayed, as-ground, and heat-treated in air and argon atmospheres. A detailed analysis of the coatings was carried out by means of XRD, SEM, and EPMA, prior and after the corrosion test. The corrosion rate was analyzed in a NaCl solution saturated with CO2. Results demonstrate that the use of a low-oxygen partial pressure favors the formation of a Cr2O3 layer on the surface of the coatings. According to the electrochemical results, the lower corrosion rates were obtained for the heat-treated coatings irrespective of the surface finishing, being the ground and argon heat-treated condition that shows the best corrosion performance. This behavior is due to the synergistic effect of the low-pressure heat treatment and the grinding processes. The grinding promotes a more homogeneous reaction area without surface heterogeneities such as voids, and the pre-oxidation treatment decreases the porosity content of the coating and also allows the growing of a Cr-rich oxide scale which acts as a barrier against the ions of the aqueous solution.

MIL-68 (In) nano-rods for the removal of Congo red dye from aqueous solution.

PubMed

Jin, Li-Na; Qian, Xin-Ye; Wang, Jian-Guo; Aslan, Hüsnü; Dong, Mingdong

2015-09-01

MIL-68 (In) nano-rods were prepared by a facile solvothermal synthesis using NaOAc as modulator agent at 100°C for 30 min. The BET test showed that the specific surface area and pore volume of MIL-68 (In) nanorods were 1252 m(2) g(-1) and 0.80 cm(3) g(-1), respectively. The as-prepared MIL-68 (In) nanorods showed excellent adsorption capacity and rapid adsorption rate for removal of Congo red (CR) dye from water. The maximum adsorption capacity of MIL-68 (In) nanorods toward CR reached 1204 mg g(-1), much higher than MIL-68 (In) microrods and most of the previously reported adsorbents. The adsorption process of CR by MIL-68 (In) nano-rods was investigated and found to be obeying the Langmuir adsorption model in addition to pseudo-second-order rate equation. Moreover, the MIL-68 (In) nanorods showed an acceptable reusability after regeneration with ethanol. All information gives an indication that the as-prepared MIL-68 (In) nanorods show their potential as the adsorbent for highly efficient removal of CR in wastewater. Copyright © 2015 Elsevier Inc. All rights reserved.

Method for the quantitation of gastric emptying time of gel test meals.

PubMed

Russell, J; Bass, P

1984-09-01

Isotopic markers were developed to allow measurement of the gastric emptying times of homogeneous and nonhomogeneous gel meals. Meals containing the dietary fibers psyllium and guar gum presented as homogeneous, viscous gels while meals containing the synthetic polymer polycarbophil presented as discrete gel particle-water mixtures. Fiber meals were labeled differently than polycarbophil meals. Fiber meals were labeled with 51Cr-CM-Sephadex. The marker was uniformly suspended in meals containing at least 1% guar or 2% psyllium. In contrast, polycarbophil particles were labeled by hydrating the dried granules with saline in which Na2(51)CrO4 had been dissolved. Use of the markers to measure gastric emptying was demonstrated in dogs fitted with duodenal cannulas. Half of the fiber meals emptied from the stomach in about 40 min without significant dilution by secretions. In contrast, only 8% of the polycarbophil particles emptied by 90 min. Particle-specific labeling of polycarbophil was important because the meal effluent was diluted extensively by secretions. We conclude that 51Cr-CM-Sephadex and soluble Cr-51 may be used as meal markers for estimation of the gastric emptying times of certain homogeneous and nonhomogeneous gel-type meals, respectively.

FUSED SALT METHOD FOR COATING URANIUM WITH A METAL

DOEpatents

Eubank, L.D.

1959-02-01

A method is presented for coating uranium with a less active metal such as Cr, Ni, or Cu comprising immersing the U in a substantially anhydrous molten solution of a halide of these less active metals in a ternary chloride composition which consists of selected percentages of KCl, NaCl and another chloride such as LiCl or CaCl/sub 2/.

Role of sodium ions in the vitrification process: glass matrix modification, slag structure depolymerization, and influence of metal immobilization.

PubMed

Kuo, Yi-Ming

2014-07-01

This study investigates the role of Na ions, a common flux, in the vitrification process. Artificial glass systems composed of Al2O3, CaO, and SiO2 with various Na concentrations were melted at 1450 degrees C. The specimens were cooled by air cooling and water quenching and the metal mobility was evaluated using a sequential extraction procedure. The X-ray diffraction analysis and scanning electron microscopy observations showed that Na ions governed the air-cooled slag's structure. Na ions initially depolymerized CaSiO3-linked chains into CaSiO3 chains, and further cut them into shorter and nonuniform ones, making the slag structure amorphous. With even more Na ions, CaSiO3 chains were divided into single SiO4 tetrahedrons and formed Na-related crystals (Na2Ca3Si2O8 and NaAlSiO4). The phase distributions of Al, Cr, Cu Mn, and Ni showed that Na has a positive effect on the immobilization of heavy metals at suitable concentrations, but a negative effect when in excess amounts. Implications: Vitrification has been widely used to treat hazardous materials. The Na-bearing additives were often used as a flux to improve the melting process. This study described the role of Na played in the vitrification process. The Na ions acted as glass modifier and depolymerize the chain structure of slag. With adequate addition amount of Na ions, the immobilization of heavy metals was improved. The results provided much information about the crystalline phase variation, metal mobility, and surface characteristics while Na serves as a flux.

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.

Investigation of the Influence of Selected Soil and Plant Properties from Sakarya, Turkey, on the Bioavailability of Trace Elements by Applying an In Vitro Digestion Model.

PubMed

Altundag, Huseyin; Albayrak, Sinem; Dundar, Mustafa S; Tuzen, Mustafa; Soylak, Mustafa

2015-11-01

The main aim of this study was an investigation of the influence of selected soil and plant properties on the bioaccessibility of trace elements and hence their potential impacts on human health in urban environments. Two artificial digestion models were used to determine trace element levels passing from soil and plants to man for bioavailability study. Soil and plant samples were collected from various regions of the province of Sakarya, Turkey. Digestive process is started by addition of soil and plant samples to an artificial digestion model based on human physiology. Bioavailability % values are obtained from the ratio of the amount of element passing to human digestion to element content of soil and plants. According to bioavailability % results, element levels passing from soil samples to human digestion were B = Cr = Cu = Fe = Pb = Li < Al < Ni < Co < Ba < Mn < Sr < Cd < Na < Zn < Tl, while element levels passing from plant samples to human digestion were Cu = Fe = Ni = Pb = Tl = Na = Li < Co < Al < Sr < Ba < Mn < Cd < Cr < Zn < B. It was checked whether the results obtained reached harmful levels to human health by examining the literature.

Determination of elements in hospital waste with neutron activation analysis method

NASA Astrophysics Data System (ADS)

Dwijananti, P.; Astuti, B.; Alwiyah; Fianti

2018-03-01

The producer of the biggest B3 waste is hospital. The waste is from medical and laboratory activities. The purpose of this study is to determine the elements contained in the liquid waste from hospital and calculate the levels of these elements. This research was done by analysis of the neutron activation conducted at BATAN Yogyakarta. The neutron activation analysis is divided into two stages: activation of the samples using neutron sources of reactor Kartini, then chopping by using a set of tools, gamma spectrometer with HPGe detector. Qualitative and quantitative analysis were done by matching the gamma spectrum peak to the Neutron Activation Table. The sample was taken from four points of the liquid waste treatment plant (WWTP) Bhakti Wira Tamtama Semarang hospital. The results showed that the samples containing elements of Cr, Zn, Fe, Co, and Na, with the levels of each element is Cr (0.033 - 0.075) mg/L, Zn (0.090 - 1.048) mg/L, Fe (2.937-37.743) mg/L, Co (0.005-0.023) mg/L, and Na (61.088-116.330) mg/L. Comparing to the standard value, the liquid is safe to the environment.

Formation of TiO2 nanostructure by plasma electrolytic oxidation for Cr(VI) reduction

NASA Astrophysics Data System (ADS)

Torres, D. A.; Gordillo-Delgado, F.; Plazas-Saldaña, J.

2017-01-01

Plasma electrolytic oxidation (PEO) is an environmentally friendly technique that allows the growth of ceramic coatings without organic solvents and non-toxic residues. This method was applied to ASME SB-265 titanium (Ti) plates (2×2×0.1cm) using voltage pulses from a switching power supply (340V) for 10 minutes at frequency of 1000Hz changing duty cycle at 10, 60 and 90% and the electrolytes were Na3PO4 and NaOH. The treated sheets surfaces were analysed by X-ray diffraction and scanning electron microscopy. According to the diffractograms, the duty cycle increase produces amorphous TiO2 coating on Ti sheets and the thickness increases. After sintering at 900°C during 1 hour, the 10% duty cycle generated a combination of anatase and rutile phases at the sample surface with weight percentages of 13.3 and 86.6% and particle sizes of 32.461±0.009nm and 141.14±0.03 nm, respectively. With this sample, the total reduction of hexavalent chromium was reached at 50 minutes for 1ppm solution. This photocatalytic activity was measured following the colorimetric method ASTM-3500-Cr B.

FERRATE TREATMENT FOR REMOVING CHROMIUM FROM HIGH-LEVEL RADIOACTIVE TANK WASTE

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

Sylvester, Paul; Rutherford, Andy; Gonzalez-Martin, Anuncia

2000-12-01

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(III) molar ratio, but the chromium removal tends to level out for Fe(VI)/Cr(III) greater than 10.more » Increasing temperature leads to better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be handled as low-activity waste.« 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.

Wetted Foam Liquid DT Layer ICF Experiments at the NIF

NASA Astrophysics Data System (ADS)

Olson, R. E.; Leeper, R. J.; Peterson, R. R.; Yi, S. A.; Zylstra, A. B.; Kline, J. L.; Bradley, P. A.; Yin, L.; Wilson, D. C.; Haines, B. M.; Batha, S. H.

2016-10-01

A key physics issue in indirect-drive ICF relates to the understanding of the limitations on hot spot convergence ratio (CR), principally set by the hohlraum drive symmetry, the capsule mounting hardware (the ``tent''), and the capsule fill tube. An additional key physics issue relates to the complex process by which a hot spot must be dynamically formed from the inner ice surface in a DT ice-layer implosion. These physics issues have helped to motivate the development of a new liquid DT layer wetted foam platform at the NIF that provides an ability to form the hot spot from DT vapor and experimentally study and understand hot spot formation at a variety of CR's in the range of 12

Electrochemical corrosion behaviour of nickel chromium-chromium carbide coating by HVOF process

NASA Astrophysics Data System (ADS)

Amudha, A.; Nagaraja, H. S.; Shashikala, H. D.

2018-04-01

To overcome the corrosion problem in marine industry, coatings are one of the most economical solutions. In this paper, the corrosion behaviour of 25(NiCr)-75Cr3C2 cermet coating on low carbon steel substrate by HVOF process is studied. Different phases such as Cr7C3 and Cr3C2, along with Ni and chromium oxide(Cr3O2) constituents present in the coating were revealed by X-Ray Diffraction (XRD) analysis. The morphology of the coating obtained by scanning electron microscope (SEM) gave confirmation for the XRD analysis. Electrochemical corrosion techniques such as Linear Polarization Resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS) were used to study the corrosion behaviour of the cermet in 3.5wt% NaCl electrolyte solution. The corrosion current density of the coated sample and substrate were found to be 6.878µA/cm-2 and 21.091µA/cm-2 respectively. The Nyquist Impedance spectra were used to derive an equivalent circuit to analyze the interaction between the coating and electrolyte. The Bode Impedance plots obtained by EIS for the coating showed a typical passive material capacitive behaviour, indicated by medium to low frequency with phase angle approaching -60o, suggesting that a stable film is formed on the tested material in the electrolyte used.

Stress Corrosion Behavior of 12Cr Martensite Steel for Steam Turbine LP Blade

NASA Astrophysics Data System (ADS)

Tianjian, Wang; Yubing, Pei; Zhenhuan, Gao; Hua, Fan; Gongxian, Yang

With the development of capacity and efficiency of coal-fired thermal power plant, the length of Low Pressure (LP) last-stage blade of steam turbine became longer. Therefore, the design static stress of blade gets closer or even higher than the yield strength of material. Because of the special operation condition of LP last stage blade, the stress corrosion crack of 12Cr-Ni-Mo-V-N Martensite stainless steel may happen especially at the root of the blade where designed the highest static stress. In this paper, the stress corrosion behavior of 12Cr-Ni-Mo-V-N Martensite stainless steels used for steam turbine LP last stage blade in 3vol% NaCl solution was studied, the constant stress is about 95%, 85%, 65% and 35% of yield stress respectively and the test was lasted for 3000 hours, the stress corrosion behavior was studied and then, the effect of shot penning strengthen for anti-stress corrosion property of 12Cr-Ni-Mo-V-N Martensitic steel was studied. The results showed that the purity of steel affects the stress corrosion behavior huge especially at the high and medium stress condition. The shot penning cannot enhances the anti-stress corrosion property of the 12Cr-Ni-Mo-V-N steel at high tensile constant stress condition, however it will make the anti-stress corrosion property better when the stress is low.

Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

NASA Astrophysics Data System (ADS)

Pranoto; Masykur, A.; Nugroho, Y. A.

2018-03-01

Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

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.

Oxidation of Alumina-Forming MAX Phases in Turbine Environments

NASA Technical Reports Server (NTRS)

Smialek, James; Garg, Anita; Harder, Bryan; Nesbitt, James; Gabb, Timothy; Gray, SImon

2017-01-01

Protective coatings for high temperature turbine components are based on YSZ thermal barriers and oxidation resistant, alumina-forming NiAl or NiCoCrAlY bond coats. Ti2AlC and Cr2AlC MAX phases are thus of special interest because of good oxidation resistance and CTE that can match Al2O3 and YSZ. Their alumina scales grow according to cubic kinetics due to grain growth in the scale, with initial heating dominated by fast TiO2 growth. Protective cubic kinetics are also found in high pressure burner rig tests of MAXthal 211 Ti2AlC, but with reduced rates due to volatile TiO(OH)2 formation in water vapor. YSZ-coatings on bulk Ti2AlC exhibit remarkable durability up to 1300C in furnace tests and at least a 25x life advantage compared to superalloys. At another extreme, Cr2AlC is resistant to low temperature Na2SO4 hot corrosion and exhibits thermal cycling stability bonded to a superalloy disk material. Accordingly, sputtered Cr2AlC coatings on disk specimens prevented hot corrosion detriments on LCF. Breakaway oxidation (Ti2AlC), scale spallation (Cr2AlC), interdiffusion, and processing as coatings still present serious challenges. However the basic properties of MAX phases provide some unusual opportunities for use in high temperature turbines.

A novel method for vanadium slag comprehensive utilization to synthesize Zn-Mn ferrite and Fe-V-Cr alloy.

PubMed

Liu, Shi-Yuan; Li, Shu-Jin; Wu, Shun; Wang, Li-Jun; Chou, Kuo-Chih

2018-07-15

Vanadium slag is a by-product from steelmaking process of vanadium-titanium magnetite, which mainly contains FeO, MnO, V 2 O 3 , and Cr 2 O 3 , The elements Fe and Mn are major components of Mn-Zn ferrite. The elements V and Cr are major components of V-Cr alloy. In view of the potential application in these study, a Mn 0.8 Zn 0.2 Fe 2 O 4 of high saturation magnetization (Ms = 68.6 emu/g) and low coercivity (Hc = 3.3 Oe) was successfully synthesized from the leaching solutions of vanadium slag by adding appropriate chemical reagents, ZnCl 2 and MnCl 2 ·4H 2 O, via roasting at 1300 °C for 1 h. The minor components (CaO and SiO 2 ) in the leaching solution of vanadium slag segregated to the grain boundaries resulting in increasing the resistivity of ferrite. The value of DC resistivity of Mn 0.8 Zn 0.2 Fe 2 O 4 at 25 °C reached 1230.7Ω m. The residue containing Fe, V and Cr was chlorinated by AlCl 3 and the Fe 3+ , V 3+ , and Cr 3+ ions were released into the NaCl-KCl eutectic. The current-time curve for the electrolysis of molten salt was investigated. Alloy (Fe, V, and Cr) of granular shape was obtained. The residue can be used to produce the mulite. This process provided a new approach to utilize slag from steelmaking. Copyright © 2018 Elsevier B.V. All rights reserved.

Catalytic Silylation of N2 and Synthesis of NH3 and N2H4 by Net Hydrogen Atom Transfer Reactions Using a Chromium P4 Macrocycle.

PubMed

Kendall, Alexander J; Johnson, Samantha I; Bullock, R Morris; Mock, Michael T

2018-02-21

We report the first discrete molecular Cr-based catalysts for the reduction of N 2 . This study is focused on the reactivity of the Cr-N 2 complex, trans-[Cr(N 2 ) 2 (P Ph 4 N Bn 4 )] (P 4 Cr(N 2 ) 2 ), bearing a 16-membered tetraphosphine macrocycle. The architecture of the [16]-P Ph 4 N Bn 4 ligand is critical to preserve the structural integrity of the catalyst. P 4 Cr(N 2 ) 2 was found to mediate the reduction of N 2 at room temperature and 1 atm pressure by three complementary reaction pathways: (1) Cr-catalyzed reduction of N 2 to N(SiMe 3 ) 3 by Na and Me 3 SiCl, affording up to 34 equiv N(SiMe 3 ) 3 ; (2) stoichiometric reduction of N 2 by protons and electrons (for example, the reaction of cobaltocene and collidinium triflate at room temperature afforded 1.9 equiv of NH 3 , or at -78 °C afforded a mixture of NH 3 and N 2 H 4 ); and (3) the first example of NH 3 formation from the reaction of a terminally bound N 2 ligand with a traditional H atom source, TEMPOH (2,2,6,6-tetramethylpiperidine-1-ol). We found that trans-[Cr( 15 N 2 ) 2 (P Ph 4 N Bn 4 )] reacts with excess TEMPOH to afford 1.4 equiv of 15 NH 3 . Isotopic labeling studies using TEMPOD afforded ND 3 as the product of N 2 reduction, confirming that the H atoms are provided by TEMPOH.

Alumina-Forming MAX Phases in Turbine Material Systems

NASA Technical Reports Server (NTRS)

Smialek, James L.; Harder, Bryan J.; Garg, Arnita; Nesbitt, James A.

2015-01-01

Coatings for high temperature turbine components are based on low conductivity YSZ thermal barriers and protective NiAl, NiCoCrAlY bond coats. Good oxidation hot corrosion resistance, intermediate CTE, and strain tolerance of Ti2AlC and Cr2AlC MAX phases are thus of special interest. Their alumina scale growth follows a cubic law in accord with FeCrAlY alloys, with oxygen grain boundary diffusivity: Dgb 1.8 x 10-10 exp(-375 kJmole) m3s. Protective cubic kinetics are also found in high pressure burner rig (6 atm., 25 ms) and TGA tests of MAXthal 211Ti2AlC. The initial portion (0.1 hr) is dominated by fast TiO2 growth (with little evidence of scale volatility in high pressure water vapor, as found for SiO2 scales). Bulk Ti2AlC and Cr2AlC substrates show promise as potential bond coats for YSZ TBCs in 1000-1200 C furnace life (500 h) tests. Cr2AlC is proving to be very resistant to 700-900 C Na2SO4 hot corrosion and is of interest for disk alloys. Preliminary diffusion bonded Cr2AlC-superalloy hybrid couples have survived 1000 hr interrupted furnace tests at 800C with no indication of cracking or debonding. Diffusion zones of -NiAl+Cr7C3 were produced in these above 1000 C, but did not grow to any great extent after 1000 hr at 800 C. Processing as coatings presents challenges, however the basic properties of MAX phases provide novel opportunities for high temperature turbine components.

Surfactant modified zeolite as amphiphilic and dual-electronic adsorbent for removal of cationic and oxyanionic metal ions and organic compounds.

PubMed

Tran, Hai Nguyen; Viet, Pham Van; Chao, Huan-Ping

2018-01-01

A hydrophilic Y zeolite was primarily treated with sodium hydroxide to enhance its cation exchange capacity (Na-zeolite). The organo-zeolite (Na-H-zeolite) was prepared by a modification process of the external surface of Na-zeolite with a cationic surfactant (hexadecyltrimethylammonium; HDTMA). Three adsorbents (i.e., pristine zeolite, Na-zeolite, and Na-H-zeolite) were characterized with nitrogen adsorption/desorption isotherms, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, cation exchange capacities, and zeta potential. Results demonstrated that HDTMA can be adsorbed on the surface of Na-zeolite to form patchy bilayers. The adsorption capacity of several hazardous pollutants (i.e., Pb 2+ , Cu 2+ , Ni 2+ , Cr 2 O 7 2- , propylbenzene, ethylbenzene, toluene, benzene, and phenol) onto Na-H-zeolite was investigated in a single system and multiple-components. Adsorption isotherm was measured to further understand the effects of the modification process on the adsorption behaviors of Na-H-zeolite. Adsorption performances indicated that Na-H-zeolite can simultaneously adsorb the metal cations (on the surface not covered by HDTMA), oxyanions (on the surface covered by HDTMA). Na-H-zeolite also exhibited both hydrophilic and hydrophobic surfaces to uptake organic compounds with various water solubilities (from 55 to 75,000mg/L). It was experimentally concluded that Na-H-zeolite is a potential dual-electronic and amphiphilic adsorbent for efficiently removing a wide range of potentially toxic pollutants from aquatic environments. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

PubMed Central

Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik

2017-01-01

Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. PMID:28772651

Similarities of biochemical abnormalities between major depressive disorder and bipolar depression: a proton magnetic resonance spectroscopy study.

PubMed

Zhong, Shuming; Wang, Ying; Zhao, Guoxiang; Xiang, Qi; Ling, Xueying; Liu, Sirun; Huang, Li; Jia, Yanbin

2014-10-01

Depression in the context of bipolar disorder (BD) is often misdiagnosed as major depressive disorder (MDD), leading to mistreatments and poor clinical outcomes for many bipolar patients. Previous neuroimaging studies found mixed results on brain structure, and biochemical metabolism of the two disorders. To eliminate the compounding effects of medication, and aging, this study sought to investigate the brain biochemical changes of treatment-naïve, non-late-life patients with MDD and BD in white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC) and hippocampus by using proton magnetic resonance spectroscopy ((1)H-MRS). Three groups of participants were recruited: 26 MDD patients, 20 depressed BD patients, and 13 healthy controls. The multi-voxel (1)H-MRS [repetition time (TR)=1000ms; echo-time (TE)=144ms] was used for the measurement of N-acetylaspartate(NAA), choline containg compounds (Cho), and creatine (Cr) in three brain locations: white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC), and hippocampus. Two ratios of NAA/Cr and Cho/Cr as a measure of brain biochemical changes were compared among three experimental groups. On the comparison of brain biochemical changes, both MDD patients and BD patients showed many similarities compared to the controls. They both had a significantly lower NAA/Cr ratio in the left WMP lobe. There were no significant differences among three experimental groups for Cho/Cr ratio in the WMP lobe, and for the ratios of NAA/Cr and Cho/Cr in the bilateral ACC and hippocampus. The only difference between MDD and BD patients existed for the NAA/Cr ratio in the right WMP lobe. While MDD patients had a significantly lower NAA/Cr ratio than controls, BD patients showed no such differences. On the comparison of correlation of medical variables and brain biochemical changes, all participants demonstrated no significant correlations. Reduced NAA/Cr ratio at the left WMP lobe indicated the dysfunction of neuronal viability in deep white matter, in both MDD and BD patients who shared similarities of brain biochemical abnormalities, which might imply an overlap in neuropathology of depression. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate in welding fume alkaline extracts by HPLC-ICP-MS.

PubMed

Ščančar, Janez; Berlinger, Balázs; Thomassen, Yngvar; Milačič, Radmila

2015-09-01

A novel analytical procedure was developed for the simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate by anion-exchange high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Linear gradient elution from 100% water to 100% 0.7 M NaCl was applied for chromatographic separation of metal species. In standard aqueous solution at neutral pH molybdate, tungstate and vanadate exist in several aqueous species, while chromate is present as a single CrO4(2-) species. Consequently, only chromate can be separated from this solution in a sharp chromatographic peak. For obtaining sharp chromatographic peaks for molybdate, tungstate and vanadate, the pH of aqueous standard solutions was raised to 12. At highly alkaline conditions single CrO4(2-), MoO4(2-) and WO4(2-) are present and were eluted in sharp chromatographic peaks, while VO4(3-) species, which predominates at pH 12 was eluted in slightly broaden peak. In a mixture of aqueous standard solutions (pH 12) chromate, molybdate, tungstate and vanadate were eluted at retention times from 380 to 420 s, 320 to 370 s, 300 to 350 s and 240 to 360 s, respectively. Eluted species were simultaneously detected on-line by ICP-MS recording m/z 52, 95, 182 and 51. The developed procedure was successfully applied to the analysis of leachable concentrations of chromate, molybdate, tungstate and vanadate in alkaline extracts (2% NaOH+3% Na2CO3) of manual metal arc (MMA) welding fumes loaded on filters. Good repeatability and reproducibility of measurement (RSD±3.0%) for the investigated species were obtained in both aqueous standard solutions (pH 12) and in alkaline extracts of welding fumes. Low limits of detection (LODs) were found for chromate (0.02 ng Cr mL(-1)), molybdate (0.1 ng Mo mL(-1)), tungstate (0.1 ng W mL(-1)) and vanadate (0.2 ng V mL(-1)). The accuracy of analytical procedure for the determination of chromate was checked by analysis of CRM 545, Cr(VI) in welding dust loaded on a filter. Good agreement between determined and reported certified values was obtained. For molybdate, tungstate and vanadate the assessment of accuracy was performed by spiking welding fume filters. Good recoveries for all investigated species (98-101%) confirmed the accuracy of the analytical procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

Recycling of ancient subduction-modified mantle domains in the Purang ophiolite (southwestern Tibet)

NASA Astrophysics Data System (ADS)

Gong, Xiao-Han; Shi, Ren-Deng; Griffin, W. L.; Huang, Qi-Shuai; Xiong, Qing; Chen, Sheng-Sheng; Zhang, Ming; O'Reilly, Suzanne Y.

2016-10-01

Ophiolites in the Indus-Yarlung Zangbo (IYZ) suture (southern Tibet) have been interpreted as remnants of the Neo-Tethyan lithosphere. However, the discovery of diamonds and super-reducing, ultra-high pressure (SuR-UHP) mineral assemblages (e.g., coesite after stishovite, olivine after wadsleyite, native metals, alloys, and moissanite) in some of these massifs and associated chromitites requires a re-evaluation of their origin and evolution. A new petrological and geochemical study of the Purang ophiolite in the western IYZ suture sheds new lights on these issues. The depleted harzburgites of the Purang massif have low modal contents of clinopyroxene (< 2%), and high Cr# [100*Cr3 +/(Cr3 + + Al3 +)] in spinel (> 40 70) and pyroxenes (> 16 in orthopyroxene, and > 20 in clinopyroxene), suggesting high degrees of melt extraction (> 20%). These features are not consistent with formation in a (ultra-) slow-spreading mid-ocean ridge. These peridotites have high modal contents of orthopyroxene; this, and the extremely high Cr# of spinels in these peridotites, suggests modification in a subduction zone. The clinopyroxene-rich harzburgites and lherzolites contain rare spinel-pyroxene symplectites after garnet. Their clinopyroxenes have low MREE-to-HREE ratios ((Sm/Yb)N < 0.1) at relatively high HREE concentrations, and are Na-rich but Nd-poor. The relatively enrichment of Na but depletion of Nd in clinopyroxene cannot be explained by refertilization with MORB melts but are consistent with an origin from Na-rich subcontinental lithospheric mantle (SCLM). All lines of evidence suggest that these peridotites underwent initial melting in the stability field of garnet-facies peridotites, followed by additional melting in the spinel-facies mantle. Whole-rock Os isotopic compositions of the Purang peridotites give ancient TRD model ages (up to 1.3 Ga), indicating that the formation of these ancient depletion residues predated the opening of Neo-Tethyan Ocean. These observations, together with recent studies on other IYZ peridotites, suggest that the Purang peridotites are genetically unrelated to the associated mafic crust. Instead, they represent ancient SCLM domains, initially formed beneath a continental margin, and then modified by subduction, before they were incorporated into the Neo-Tethyan ocean basin. This model is consistent with the deep-mantle-recycling model for the presence of SuR-UHP phases in the IYZ ophiolites. The infiltration of MORB melts through these ancient depleted peridotites during their final exhumation in a (ultra-) slow-spreading center may have refertilized them to produce the clinopyroxene-rich peridotites.

Arctic Ice Studies

DTIC Science & Technology

1993-02-01

Aeronautics and Space Administration; DMSP: Defense Meteorological Satellit= innovative helicopter survey for ambient Program; AVHRR: Advanced Very High...a" aA z’•Lae Na g 419" .aso ." -I Nas"o Te a ’ b 0 York A4CJ ’ crk A19. YCrk t•nrtid 0 .436 b = -. 49cr9k Trott *._-. 3 - -. Now A19. No~v, AtC. Nowv

The speciation and transport of palladium in hydrothermal fluids: Experimental modeling and thermodynamic constraints

NASA Astrophysics Data System (ADS)

Tagirov, Boris R.; Baranova, Nina N.; Zotov, Alexandr V.; Akinfiev, Nikolay N.; Polotnyanko, Natalya A.; Shikina, Nadezhda D.; Koroleva, Lyudmila A.; Shvarov, Yuri V.; Bastrakov, Evgeniy N.

2013-09-01

The solubility of PdO(cr) was measured in NaOH (to 0.1m, mol/kg H2O) solutions at 400 °C, 1 kbar, and the solubility of Pd(cr) was determined at 400-500 °C, 1 kbar in acidic chloride solutions (to 1.5m NaCl) buffered with respect to hydrogen. The Pd electrode potential Eo(PdCl42-)/Pd for the reaction PdCl42- + 2e- = Pd(cr) + 4 Cl- was determined at 50 and 70 °C in 1m chloride solutions. These data, together with reliable literature values, were used for calculation of the standard thermodynamic properties and the formation constants for Pd-OH, Pd-Cl, and Pd-S-HS complexes within the framework of the revised Helgeson-Kirkham-Flowers model. It was found that PdCl3- and PdCl42- become the most important Pd complexes in high temperature (t > 300 °C), chloride-rich fluids, and PdCl42- predominates at m(Cl) > 0.1. The stability of Pd-Cl complexes increases sharply with increase in temperature. The near-neutral chloride-sulfide solutions (1m NaCl, <0.1m Stot) can transport Pd at ppm concentration levels at t ⩾ 600 °C, whereas decrease in temperature and increase in pH can lead to effective deposition of Pd minerals. The stability of Pd-S-HS complexes (Pd(°, Pd(HS)3- and PdS(HS)2-) decreases with increase in temperature. Therefore, the role of these complexes in hydrothermal transport of palladium is restricted to the low temperature solutions (t < 100 °C) and sulfur can be considered an efficient depositing agent for Pd. The calculated HKF Equation of State parameters were used to predict thermodynamic properties of Pd2+, Pd-OH, Pd-Cl, and Pd-S-HS complexes to 700 °C, 2 kbar. These parameters are incorporated into the FreeGs web-enabled database (http://www-b.ga.gov.au/minerals/research/methodology/geofluids/thermo/calculator/search.jsp) that can be used for geochemical application of thermodynamic data obtained in the present study.

Structure and corrosion properties of PVD Cr-N coatings

NASA Astrophysics Data System (ADS)

Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

2002-05-01

PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

Modulation of microenvironmental pH for dual release and reduced in vivo gastrointestinal bleeding of aceclofenac using hydroxypropyl methylcellulose-based bilayered matrix tablet.

PubMed

Kang, Won-Ho; Nguyen, Hien Van; Park, Chulhun; Choi, Youn-Woong; Lee, Beom-Jin

2017-05-01

This study was designed to develop a once-daily controlled-release matrix tablet of aceclofenac 200mg (AFC-CR) with dual release characteristics and to investigate the role of an alkalizer in enhancing drug solubility and reducing the occurrence of gastroduodenal mucosal lesions. Two formulation approaches were employed, namely a monolithic matrix tablet and a bilayered tablet. In vitro dissolution studies of AFC-CR tablets were carried out in simulated intestinal fluid (pH6.8 buffer). The in vivo pharmacokinetic studies and drug safety of the immediate-release reference tablet Airtal® 100mg (Daewoong Co., Korea) and the optimized AFC-CR tablet were compared in beagle dogs under fasted condition. The optimally selected AFC-CR formulation displayed the desired dual release characteristics in simulated intestinal fluid with satisfactory micromeritic properties. The swelling action of the optimal matrix tablet, which was visualized by near-infrared (NIR) chemical imaging, occurred rapidly following hydration. Incorporation of sodium carbonate (Na 2 CO 3 ) was found to enhance the release rate of the AFC-CR bilayered tablets at early stages and increase the microenvironmental pH (pH M ). A pharmacokinetic study in beagle dogs indicated a higher drug plasma concentration and a sustained-release pattern for the AFC-CR tablet compared to the Airtal® tablet. AFC-CR was also superior to Airtal® in terms of in vivo drug safety, since no beagle dog receiving AFC-CR experienced gastrointestinal bleeding. The significant enhancement of drug safety was attributed to the size reduction and the increase of pH M of drug particles by means of incorporation of the alkalizer. These findings provide a scientific rationale for developing a novel controlled-release matrix tablet with enhanced patient compliance and better pain control. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanism of corrosion of Ni base superalloys by molten Na2MoO4 at elevated temperatures

NASA Technical Reports Server (NTRS)

Misra, A. K.; Stearns, C. A.

1983-01-01

The corrosion of nickel base superalloy, U-700, by molten Na2MoO4 was studied in the temperature range of 750 deg to 950 deg C. After an induction period, the rate of corrosion is linear and catastrophic corrosion is observed. It is shown that the induction period is associated with the attainment of a minimum MoO3 activity in the melt, which corresponds to the equilibrium MoO3 activity for the reaction, 2MoO3(l) + Mo = 3MoO2(s). A mechanism is proposed to describe the catastrophic nature of corrosion, which involves transport of Ni++ through the melt resulting in formulation of NiO at the melt gas interface and basic fluxing of Cr2O3. The effect of the amount of Na2MoO4 on the corrosion kinetics was also studied. It is found that evaporation and the thermodynamic calculations for the Na2MoO4 - MoO3 system the activity of MoO3 is reduced considerably when dissolved in Na2MoO4, which causes a sharp decrease in the rate of evaporation of MoO3 from a Na2MoO4 - MoO3 melt.

Combustion synthesis of complex oxides

NASA Astrophysics Data System (ADS)

Ming, Qimin

Advanced ceramic materials have numerous applications in electronic engineering, chemical engineering, and semiconductor industry. The synthesis of these materials at an economical cost is the bottleneck in the application of these materials. Self-propagating High-temperature Synthesis (SHS) is a new technique for producing these materials for exothermic systems by a combustion wave that propagates and produces high purity products. The full potential of SHS to produce advanced materials has not yet been utilized. In this study, we used SHS to prepare two types of complex oxides: La 1-xSrxCrO3, La0.89Sr0.1 MnO3, powders, used to make interconnect and cathode of solid oxide fuel cells; and chromium- and gallium-doped La1-xSr xFeO3-delta, mixed ionic and electronic conductive powders used to manufacture ceramic membranes for oxygen separation. A thermodynamic feasibility analysis shows that the oxidation of Cr is the main source of heat generation of La1-xSrxCrO 3, which maintains a stable reaction front. Replacing part of the metallic Cr in the reaction mixture by its oxides decreases the combustion temperature and front propagating velocity and modifies the product morphology. The oxygen needed for the Cr oxidation is provided by the decomposition of CrO3 , SrO2, or NaClO4. The predicted and observed combustion temperatures are in reasonable agreement. TG/DTA analyses of La1-xSrxCrO3 indicated that SHS stability was strongly affected by the transport of oxygen between the two regions, in which oxygen was generated by the decomposition of either NaClO4 or CrO3 and that in which it was consumed by the oxidation of Cr. Partial melting at the high combustion temperature during SHS of La 1-xSrxMnO3 increased product homogeneity. The electrical conductivity at 1000°C in air of SHS-produced cathode material (of 180 O-1·cm-1) matches that of the commercial product made by other processes. However, the SHS process provides much higher productivity and decreases processing time and the consumption of the electrical power. SrFeO3-x and LaCrO3 were the main intermediates and products for SHS of chromium-doped La0.2Sr0.8FeO 3-delta. The final structure was a solid solution of Fe and Sr rich oxides and La and Cr rich oxides. Decreasing the reactant particle size increased the homogeneity of the SHS product and increased the velocity of the propagating combustion front. The SHS produced La0.2Sr 0.8Cr0.2Fe0.8O3-delta had a maximal electrical conductivity of 8.8 O-1·cm -1 at 560°C in a pure oxygen. The material, having the highest stability in reducing conditions, had a moderate oxygen permeation rate of 3.35 x 10-9 mol/s·cm2 at 980°C in an oxygen partial pressure gradient from air to 4 x 10 -5 atm. The homogeneity and particle size of the combustion product of gallium-doped La0.5Sr0.5FeO3-delta may be increased by decreasing the cooling rate of the sample, either by increasing the sample diameter or by controlling the post-combustion temperature. The perovskite oxide maintained its cubic structure at all temperatures (from 20 to 1000°C) in air. However, decomposition occurred at 860°C under a simulated synthesis gas environment (22%CH4+21%CO2+57%H2, oxygen partial pressure of about 10-21 atm). Its maximal electrical conductivity was 142 O-1·cm-1 at 580°C under oxygen pressure of 1 atm. This material is suitable for use as a membrane in synthesis gas production, since the thermal expansions in air and reducing conditions are rather close at high temperatures.

Multi-Elements in Source Water (Drinking and Surface Water) within Five Cities from the Semi-Arid and Arid Region, NW China: Occurrence, Spatial Distribution and Risk Assessment

PubMed Central

Wu, Ting; Li, Xiaoping; Yang, Tao; Sun, Xuemeng; Cai, Yue; Ai, Yuwei; Zhao, Yanan; Liu, Dongying; Zhang, Xu; Li, Xiaoyun; Wang, Lijun; Yu, Hongtao

2017-01-01

The purpose of this study was to identify the concentration of multi-elements (MEs) in source water (surface and drinking water) and assess their quality for sustainability. A total of 161 water samples including 88 tap drinking waters (DW) and 73 surface waters (SW) were collected from five cities in Xi’an, Yan’an, Xining, Lanzhou, and Urumqi in northwestern China. Eighteen parameters including pH, electrical conductivity (EC), total organic carbon (TOC) total nitrogen (TN), chemical compositions of anions (F−, Cl−, NO3−, HCO3−, SO42−), cations (NH4+, K+, Na+, Ca2+, Mg2+), and metals (lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu)) were analyzed in the first time at the five cities . The results showed that pH values and concentrations of Cl−, SO42−, Na+, K+, Ca2+, Mg2+ and Cd, Cr, Cu in DW were within the permissible limits of the Chinese Drinking Water Quality Criteria, whereas the concentrations of other ions (F−, NO3−, NH4+ and Pb) exceeded their permissible values. In terms of the SW, the concentrations of F−, Cl−, NO3−, SO42− were over the third range threshold i.e., water suitable for fishing and swimming of the Surface Water Quality Standards in China. The spatial distributions of most MEs in source water are similar, and there was no clear variation for all ions and metals. The metals in DW may be caused by water pipes, faucets and their fittings. The noncarcinogenic risk of metals in DW for local children are in decreasing order Cr > Cd > Pb > Cu. The carcinogenic risk from Cr exposure was at the acceptable level according to threshold of USEPA. Although the comprehensive index of potential ecological assessment of Cr, Cd, Pb and Cu in SW ranked at low risk level and was in the order of Huang River in Xining > Peaceful Canal in Urumqi > Yan River in Yan’an > Yellow River in Lanzhou, their adverse effects to ecology and human health at a low concentration in local semi-arid and arid areas should not be ignored in the long run. PMID:28974043

Phase I/II evaluation of RV1001, a novel PI3Kδ inhibitor, in spontaneous canine lymphoma.

PubMed

Gardner, Heather L; Rippy, Sarah B; Bear, Misty D; Cronin, Kim L; Heeb, Heather; Burr, Holly; Cannon, Claire M; Penmetsa, Kumar V; Viswanadha, Srikant; Vakkalanka, Swaroop; London, Cheryl A

2018-01-01

RV1001 is a novel, potent, and selective PI3Kδ inhibitor. The purpose of this study was to evaluate the safety and efficacy of RV1001 in canine Non-Hodgkin lymphoma (NHL). Inhibition of endogenous pAKT by RV1001 in primary canine NHL cells was determined by Western blotting. A phase I study of RV1001 was performed in 21 dogs with naïve and drug resistant T and B-cell NHL to assess safety, pharmacokinetic profile, and response to therapy. The objective response rate was 62% (complete response (CR) n = 3; partial response (PR) n = 10), and responses were observed in both naïve and chemotherapy-resistant B and T cell NHL. This study provided the recommended starting dose for a phase II, non-pivotal, exploratory, open label multi-centered clinical trial in 35 dogs with naïve and drug resistant T and B-cell NHL, to further define the efficacy and safety profile of RV1001. The objective response rate in the phase II study was 77% (CR n = 1; PR n = 26). Clinical toxicities were primarily hepatobiliary and gastrointestinal, and were responsive to dose modifications and/or temporary drug discontinuation. Hepatotoxicity was the primary dose limiting toxicity. RV1001 exhibits good oral bioavailability, an acceptable safety profile, and biologic activity with associated inhibition of pAKT in dogs with B and T cell NHL. Data from these studies can be leveraged to help inform the design of future studies involving isoform-selective PI3K inhibitors in humans.

Development of a SREX Flowsheet for the Separation of Strontium from Dissolved INEEL Zirconium Calcine

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

Law, Jack Douglas; Wood, David James; Todd, Terry Allen

1999-02-01

Laboratory experimentation has indicated that the SREX process is effective for partitioning 90 Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run #64 pilot plant calcine spiked with 85 Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4',4'(5')-di-(tert-butylcyclohexo)-18-crown-6 andmore » 1.5 M TBP in Isopar-L.), a 1.0 M NaNO3 scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO3 strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO3 wash section to remove degradation products from the solvent, and a 0.1 M HNO3 rinse section. The behavior of 85 Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted 85 Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for 85 Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO3 resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO3 scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable.« less

Development of a SREX flowsheet for the separation of strontium from dissolved INEEL zirconium calcine

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

Law, J.D.; Wood, D.J.; Todd, T.A.

1999-01-01

Laboratory experimentation has indicated that the SREX process is effective for partitioning {sup 90}Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run No.64 pilot plant calcine spiked with {sup 85}Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4{prime},4{prime}(5{prime})-di-(tert-butylcyclohexo)-18-crown-6 andmore » 1.5 M TBP in Isopar-L.), a 1.0 M NaNO{sub 3} scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO{sub 3} strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO{sub 3} wash section to remove degradation products from the solvent, and a 0.1 M HNO{sub 3} rinse section. The behavior of {sup 85}Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted {sup 85}Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for {sup 85}Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO{sub 3} resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO{sub 3} scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable.« less

Magnetic properties and hyperfine interactions in Cr{sub 8}, Cr{sub 7}Cd, and Cr{sub 7}Ni molecular rings from {sup 19}F-NMR

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

Bordonali, L.; Borsa, F.; Consorzio INSTM, Via Giusti 9, I-50121 Firenze

2014-04-14

A detailed experimental investigation of the {sup 19}F nuclear magnetic resonance is made on single crystals of the homometallic Cr{sub 8} antiferromagnetic molecular ring and heterometallic Cr{sub 7}Cd and Cr{sub 7}Ni rings in the low temperature ground state. Since the F{sup −} ion is located midway between neighboring magnetic metal ions in the ring, the {sup 19}F-NMR spectra yield information about the local electronic spin density and {sup 19}F hyperfine interactions. In Cr{sub 8}, where the ground state is a singlet with total spin S{sub T} = 0, the {sup 19}F-NMR spectra at 1.7 K and low external magnetic fieldmore » display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the {sup 19}F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S{sub T} = 1. In the heterometallic rings, Cr{sub 7}Cd and Cr{sub 7}Ni, whose ground state is magnetic with S{sub T} = 3/2 and S{sub T} = 1/2, respectively, the {sup 19}F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the {sup 19}F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F{sup −}-Ni{sup 2+} and the F{sup −}-Cd{sup 2+} bonds. The values of the hyperfine constants compare well to the ones known for F{sup −}-Ni{sup 2+} in KNiF{sub 3} and NiF{sub 2} and for F{sup −}-Cr{sup 3+} in K{sub 2}NaCrF{sub 6}. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F{sup −} ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.« less

Proton magnetic resonance spectroscopy in obsessive-compulsive disorder: evidence for reduced neuronal integrity in the anterior cingulate.

PubMed

Tükel, Raşit; Aydın, Kubilay; Ertekin, Erhan; Özyıldırım, Seda Şahin; Taravari, Vedat

2014-12-30

Neuroimaging studies have suggested that dysfunction of the cortico-striatal-thalamo-cortical (CSTC) circuit is a key pathophysiologic feature of obsessive-compulsive disorder (OCD). Several studies using proton magnetic resonance spectroscopy ((1)H MRS) have found abnormal neural metabolite concentrations among OCD patients. The aim of this study was to investigate the metabolic integrity of the anterior cingulate, caudate and putamen in OCD. In the present study, 32 unmedicated patients with OCD, including 23 who were drug-naïve, were compared using MRS with 32 healthy controls. Metabolite levels of N-acetylaspartate (NAA), choline (Cho) and myo-inositol (mI) were measured in terms of their ratios to creatine (Cr). The ratio of NAA/Cr was significantly lower in OCD patients than in healthy controls in the anterior cingulate. There was a tendency for levels of NAA/Cr to be lower in the caudate and the putamen in patients with OCD compared with healthy controls. NAA/Cr ratios were negatively correlated with the total scores on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) in the anterior cingulate in patients with OCD. Our results support the significance and biochemical involvement of the anterior cingulate cortex (ACC) in the pathophysiology of OCD. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Application of Sawdust modified with m-DMDHEU/Choline chloride for the removal of CrO4 2- and H2AsO4 - in water

NASA Astrophysics Data System (ADS)

Dang, N. T.; Quan, P. T.; Sang, P. H. P.

2017-06-01

This article studies the use of acacia auriculiformis wood sawdust modified with 4,5-dihydroxy-1,3-bis (methoxymethyl) imidazolidin-2-one (m-DMDHEU) and choline chloride for separating CrO4 2- and H2AsO4 - ions in water. NaOH 0.2N/ethanol 70° solution was used to remove lignin from the raw material, the material was then immersed in m-DMDHEU/choline chloride aqueous solution for 24 hours, after that the material was activated at 140oC for one hour. The ability to adsorb and exchange ions of the material was examined using solutions containing CrO4 2- and H2AsO4 - ions in different conditions. The results suggested that the ability to separate CrO4 2- and H2AsO4 - ions of the modified material was better than that of anion resin at pH = 7.0; the chromate adsorption capacity was the highest in acidic condition; the presence of arsenate (V) anions had no effect on the ability to remove chromate. Lastly, the modified material was used to treat water samples containing concentrations of arsenic similar to groundwater in several arsenic-contaminated areas of Vietnam.

Effect of nitroso complexes of some transition metals on the activity of soluble guanylate cyclase.

PubMed

Severina, I S; Bussygina, O G; Grigorjev, N B

1992-03-01

Effects of nitroso complexes of some transition metals (Fe, Co, Cr), differing in the character of NO oxidation on the activity of human and rat platelet guanylate cyclase were studied. 3 types of nitroso complexes were used: (1) NO group carries a positive charge--a nitrosonium cation (Na2[FeNO + (CN)5]-nitroprusside); (2) NO is neutral--(K3[CrNO(CN)5 and [CoNO(NH3)5]SO4) and (3) NO is coordinated as anion NO- (K3[CoNO-(CN)5]. It is shown that the highest stimulatory effect is produced by sodium nitroprusside, whose activating action is due to the interaction of its NO group with the guanylate cyclase heme. Nitroso complexes (Co and Cr) the NO group of which is neutral stimulated guanylate cyclase activity insignificantly and this activation was not guanylate cyclase heme directed. Nitroso complex (Co) with NO coordinated as anion NO(-)--is a guanylate cyclase inhibitor. In contrast to nitroprusside, the nitroso complexes used (Co and Cr) have no hypotensive effect. It was concluded that the essential requirement for the realization of the hypotensive effect of transition metals' nitroso complexes is the ability of these compounds to activate soluble guanylate cyclase solely by the heme-dependent mechanism.

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.

Searching for order in chaos: a sediment stratigraphical study of a multiple-impacted bay of the Baltic Sea

NASA Astrophysics Data System (ADS)

Vaalgamaa, S.; Korhola, A.

2004-02-01

The lithological and geochemical properties of sediment cores collected from a heavily impacted embayment in the Gulf of Finland, Baltic Sea, were investigated. Hillonlahti Bay has been the focus of much human activity, including timber and oil industries, transportation, housing, dredging and waste discharge, thus constituting an exceptionally challenging environment for sediment studies. A total of nine cores were sampled along perpendicular transects across the elongated bay, and described lithologically in the field. Major and trace element concentrations were determined for a "master core" taken from the central area of the bay. The vertical distribution of 210Pb, 137Cs and spheroidal carbonaceous particles (SCP) was also examined in order to provide a chronological framework for the sediment. Changes in the sediment nature and differences in the distributions of soluble heavy metals (Cd, Cr, Cu, Ni, V, Zn), lithophilous (Al, Ti, K, Mg, Ca, Na), redox-sensitive (Fe, Mn), and nutrient (TP) elementary concentrations were related to temporal and spatial processes. These include the building of the Hamina port starting in the mid-1930s, establishment of the timber and oil industry in 1950-1960s, construction of railway embankments in 1950 and 1996, increasing urbanisation from 1960s, and wastewater discharge between 1950 and 1987. The use of Cr as a preservative in the wood processing industry is reflected in the marked enrichment of Cr in the sediment, while the influence of wastewater discharge can be seen in the sediment record by a rise in concentrations of P and evidently organically bound Na, Cu and Zn. The results are encouraging in demonstrating that via a rather simple repertoire of sediment-analytical methods it is possible to obtain information about the land-use history and contamination in such a strongly rampaged system.

Searching for “LiCr{sup II}PO{sub 4}”

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

Mosymow, E.; Glaum, R., E-mail: rglaum@uni-bonn.de; Kremer, R.K.

The two new phosphates LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} and Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} are discovered as equilibrium phases (ϑ=800 °C) in the quarternary system Li/Cr/P/O. Their crystal structures have been determined from single-crystal X-ray diffraction data (LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}: violet-blue, Pnma (no. 62), Z=4, a=6.175(1) Å, b=14.316(3) Å, c=10.277(2) Å, 100 parameters, R{sub 1}=0.028, wR{sub 2}=0.08, 2060 unique reflections with F{sub o}>4σ(F{sub o}); Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4}: greyish-green, P1{sup ¯} (no. 2), Z=1, a=4.9379(7) Å, b=7.917(2) Å, c=8.426(2) Å, α=109.98(2)°, β=90.71(1)°, γ=104.91(1)°, 131 parameters, R{sub 1}=0.022, wR{sub 2}=0.067, 1594 unique reflectionsmore » with F{sub o}>4σ(F{sub o})). Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} adopts an hitherto unknown structure type. The crystal structure of LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} is isotypic to that of NaCd{sup II}{sub 4}(PO{sub 4}){sub 3} and related to that of the mineral silicocarnotite Ca{sub 5}(PO{sub 4}){sub 2}(SiO{sub 4}). Significant disorder between Li{sup +} and Cr{sup 2+} is observed for both crystal structures. The oxidation states assigned to chromium in these two phosphates are in agreement with UV/vis/NIR absorption spectra and magnetic susceptibility data recorded for both compounds. Instead of “LiCr{sup II}PO{sub 4}” mixtures of LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}, Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4}, Cr{sub 2}O{sub 3}, and CrP are observed at equilibrium. Instead of “Li{sub 2}Cr{sup II}P{sub 2}O{sub 7}” four-phase mixtures consisting of Li{sub 9}Cr{sup III}{sub 3}(P{sub 2}O{sub 7}){sub 3}(PO{sub 4}){sub 2}, Li{sub 3}Cr{sup III}{sub 2}(PO{sub 4}){sub 3}, LiCrP{sub 2}O{sub 7}, and CrP were obtained. - Graphical abstract: Investigations on the equilibrium relations in the system Li/Cr/P/O revealed the two hitherto unknown phosphates Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} and LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}. They form instead of “LiCr{sup II}PO{sub 4}”. The crystal structures, magnetic behavior and optical spectra of these phosphates are reported. - Highlights: • The two new phosphates Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} and LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} have been characterized. • Optical spectra and paramagnetism of the these phosphates are explained by AOM. • Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4}, LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}, Cr{sub 2}O{sub 3}, and CrP occur instead of “LiCr{sup II}PO{sub 4}”. • LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} is structurally closely related to Silicocarnotite Ca{sub 5}(PO{sub 4}){sub 2}(SiO{sub 4}). • Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} and LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} exhibit significant cation disorder Li{sup +}/Cr{sup 2+}.« less

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

NASA Astrophysics Data System (ADS)

Ye, Qingfeng; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Li, Ruifeng; Huang, Jian; Wu, Yixiong

2017-02-01

Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower icorr than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted Rt value reaches its maximum at 24 h during a 48 h' immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H2SO4 reveals that corrosion starts from Cr-depleted interdendrites.

Study of Adsorption Mechanism of Congo Red on Graphene Oxide/PAMAM Nanocomposite

PubMed Central

Rafi, Mohammad; Samiey, Babak; Cheng, Chil-Hung

2018-01-01

Graphene oxide/poly(amidoamine) (GO/PAMAM) nanocomposite adsorbed high quantities of congo red (CR) anionic dye in 0.1 M NaCl solution, with the maximum adsorption capacity of 198 mg·g−1. The kinetics and thermodynamics of adsorption were investigated to elucidate the effects of pH, temperature, shaking rate, ionic strength, and contact time. Kinetic data were analyzed by the KASRA model and the KASRA, ISO, and pore-diffusion equations. Adsorption adsorption isotherms were studied by the ARIAN model and the Henry, Langmuir, and Temkin equations. It was shown that adsorption sites of GO/PAMAM at experimental conditions were phenolic hydroxyl groups of GO sheets and terminal amine groups of PAMAM dendrimer. Analysis of kinetic data indicated that amine sites were located on the surface, and that hydroxyl sites were placed in the pores of adsorbent. CR molecules interacted with the adsorption sites via hydrogen bonds. The molecules were adsorbed firstly on the amine sites, and then on the internal hydroxyl sites. Adsorption kinetic parameters indicated that the interaction of CR to the –NH3+ sites was the rate-controlling step of adsorption of CR on this site and adsorption activation energies calculated for different parts of this step. On the other hand, kinetic parameters showed that the intraparticle diffusion was the rate-controlling step during the interaction of CR molecules to –OH sites and activation energy of this step was not calculable. Finally, the used GO/PAMAM was completely regenerated by using ethylenediamine. PMID:29587463

First liquid-layer implosion experiments at the NIF

NASA Astrophysics Data System (ADS)

Zylstra, Alex

2017-10-01

Replacing the standard ice layer in an ignition design with a liquid layer allows fielding the target with a higher central vapor pressure, leading to reduced implosion convergence ratio (CR). At lower CR, the implosions are expected to be more robust to instabilities and asymmetries than standard ice-layer designs, and are also unique in that the hot spot can be primarily formed from material originating in the central fuel vapor. The first liquid-layer implosions on the National Ignition Facility (NIF) have been performed by wicking the liquid fuel into a supporting foam that lines the inside surface of the capsule. A series of shots has been conducted between CR of 12 and 20 using a HDC ablator driven by a 3-shock pulse in a near-vacuum Au hohlraum. At the lowest CR the implosion performance is well predicted by 2-D radiation-hydrodynamics calculations. However, as the CR is increased the nominal simulations do not capture the experimentally observed trends. Data-based models suggest that the hot spot formation is unexpectedly suppressed at higher convergence. The data could be explained by reduced hydrodynamic coupling efficiency, or an anomalously enhanced thermal conductivity in the mixed DT/foam material. We show that the latter hypothesis can explain observed trends in several experimental metrics, including the yield, ion temperature, and burn duration. This work was performed under the auspices of the U.S. DoE by LANL under contract DE-AC52-06NA52396.

Selenium Administration Alleviates Toxicity of Chromium(VI) in the Chicken Brain.

PubMed

Hao, Pan; Zhu, Yiran; Wang, Shenghua; Wan, Huiyu; Chen, Peng; Wang, Yang; Cheng, Ziqiang; Liu, Yongxia; Liu, Jianzhu

2017-07-01

Selenium (Se) can play a protective role against heavy metal toxicity. This experiment aims to evaluate the effect of Se supplementation at different doses on the chicken brains. Oxidative stress was induced in the chicken brains by chromium(VI). A total of 105 Hyland brown male chickens were randomly divided into seven groups, including the control group, poisoned group [6%LD 50 K 2 Cr 2 O 7 body weight (B.W.)], and detoxification groups K 2 Cr 2 O 7 (6%LD 50 ) + Se (0.31, 0.63, 1.25, 2.50, and 5.00 Na 2 SeO 3 mg/kg B.W.) orally in water for 42 days. The chickens were detected by the activities of mitochondrial membrane potential, 2'-benzoyloxycinnamaldehyde, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), and Ca 2+ -ATPase. Cr(VI) administration caused histopathological damage. In addition, changes in oxidative stress indicators were observed in the chicken's brains. Se supplement increased the levels of GSH, mitochondrial membrane potential (MMP), and Ca 2+ -ATPase and reduced MDA activity in the detoxification groups. However, the high-dose Se supplementation groups of 2.50 and 5.00 mg/kg reduced the activities of GSH, MMP, and Ca 2+ -ATPase; increased the brain-body ratio; and increased SOD activity. In conclusion, Cr(VI) exposure caused oxidative stress. Se exerted a remission effect on toxic responses in the chicken brains. However, a high Se concentration was synergistic to the toxic effect of Cr(VI).

Measurement and simulation of the cross sections for nuclide production in {sup 56}Fe and {sup nat}Cr targets irradiated with 0.04- to 2.6-GeV protons

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

Titarenko, Yu. E., E-mail: Yury.Titarenko@itep.ru; Batyaev, V. F.; Titarenko, A. Yu.

The cross sections for nuclide production in thin {sup 56}Fe and {sup nat}Cr targets irradiated by 0.04-2.6-GeV protons are measured by direct {gamma} spectrometry using two {gamma} spectrometers with the resolutions of 1.8 and 1.7 keV for the {sup 60}Co 1332-keV {gamma} line. As a result, 649 yields of radioactive residual product nuclei have been obtained. The {sup 27}Al(p, x){sup 22}Na reaction has been used as a monitor reaction. The experimental data are compared with the MCNPX (BERTINI, ISABEL), CEM03.02, INCL4.2, INCL4.5, PHITS, and CASCADE07 calculations.

Preparation of Trivalent Chromium and Rare Earth Composite Conversion Coating on Aluminum Alloy Surface

NASA Astrophysics Data System (ADS)

Huang, Jianzhen

2018-01-01

In this paper, the surface conversion film on 6063 aluminum alloy was prepared by chemical plating process with chromium sulfate, lanthanum sulfate and sodium phosphate as film forming agent. The corrosion resistance and surface morphology of the conversion film were analyzed by pitting corrosion test of copper sulfate and SEM. The results show that when Cr2(SO4)3 is 10 g/L, La2(SO4)3 is 2 g/L, Na3PO4 is 8 g/L, pH value is 3, temperature is 40 °C, reaction time is 10 min, the corrosion resistance of the surface conversion film is the best. The conversion coating is light green, composed of Cr, La, P, Al, O and other elements.

Studies on the hot corrosion of a nickel-base superalloy, Udimet 700

NASA Technical Reports Server (NTRS)

Misra, A. K.

1984-01-01

The hot corrosion of a nickel-base superalloy, Udimet 700, was studied in the temperature range of 884 to 965 C and with different amounts of Na2SO4. Two different modes of degradation were identified: (1) formation of Na2MoO4 - MoO3 melt and fluxing by this melt, and (2) formation of large interconnected sulfides. The dissolution of Cr2O3, TiO2 in the Na2SO4 melt does not play a significant role in the overall corrosion process. The conditions for the formation of massive interconnected sulfides were identified and a mechanism of degradation due to sulfide formation is described. The formation of Ns2MoO4 - MoO3 melt requires an induction period and various physiochemical processes during the induction period were identified. The factors affecting the length of the induction period were also examined. The melt penetration through the oxide appears to be the prime mode of degradation whether the degradation is due to the formation of sulfides or the formation of the Na2MoO4 - MoO3 melt.

Trace elements and electrolytes in human resting mixed saliva after exercise

PubMed Central

Chicharro, J. L.; Serrano, V.; Urena, R.; Gutierrez, A. M.; Carvajal, A.; Fernandez-, H; Lucia, A.

1999-01-01

OBJECTIVES: Exercise is known to cause changes in the concentration of salivary components such as amylase, Na, and Cl. The aim of this investigation was to evaluate the effect of physical exercise on the levels of trace elements and electrolytes in whole (mixed) saliva. METHODS: Forty subjects performed a maximal exercise test on a cycle ergometer. Samples of saliva were obtained before and immediately after the exercise test. Sample concentrations of Fe, Mg, Sc, Cr, Mn, Co, Cu, Zn, Se, Sr, Ag, Sb, Cs, and Hg were determined by inductively coupled plasma mass spectrometry and concentrations of Ca and Na by atomic absorption spectrometry. RESULTS: After exercise, Mg and Na levels showed a significant increase (p < 0.05) while Mn levels fell (p < 0.05). Zn/Cu molar ratios were unaffected by exercise. CONCLUSIONS: Intense physical exercise induced changes in the concentrations of only three (Na, Mg, and Mn) of the 16 elements analysed in the saliva samples. Further research is needed to assess the clinical implications of these findings. 


 PMID:10378074

Accumulating pollutants in conifer needles on an Atlantic island - a case study with Pinus canariensis on Tenerife, Canary Islands.

PubMed

Tausz, Michael; Trummer, Walter; Goessler, Walter; Wonisch, Astrid; Grill, Dieter; Naumann, Simone; Jiménez, Maria Soledad; Morales, Domingo

2005-08-01

Concentrations of potential pollutant elements Na, Cl, and S were investigated in needles of Pinus canariensis grown at 55 field plots in Tenerife. Microelement concentrations (including heavy metals) were measured at a subset of 18 plots. Na and Cl concentrations were high at low elevations (up to 8 mg g(-1) Cl and 5.5 mg g(-1) Na). Na/Cl ratio close to standard seawater indicated sea spray influence up to 1200 m a.s.l. Only at few plots, sulphur concentrations indicated possible pollutant impact. Cluster and correlation analyses identified a related group of V, As, Cr, Fe, Mo, Ni, Cu, Pb, and Al, possibly related to traffic exhaust aggregated with soil particles. Mainly north-eastern, lower elevated plots were exposed to those immissions, but metal concentrations were generally low compared to data from other studies. In conclusion, seawater and soil particles explained most of the element distribution pattern in pine needles in Tenerife, but strong indications for some effect of local sources of air pollutants were detected.

Design, characterization and evaluation of hydroxyethylcellulose based novel regenerable supersorbent for heavy metal ions uptake and competitive adsorption.

PubMed

Abbas, Azhar; Hussain, Muhammad Ajaz; Sher, Muhammad; Irfan, Muhammad Imran; Tahir, Muhammad Nawaz; Tremel, Wolfgang; Hussain, Syed Zajif; Hussain, Irshad

2017-09-01

Hydroxyethylcellulose succinate-Na (HEC-Suc-Na) was designed and evaluated for removal of some heavy metal ions from aqueous solution. Pristine sorbent HEC-Suc-Na was thoroughly characterized by FTIR and solid-state CP/MAS 13 C NMR spectroscopy, SEM-EDS and zero point charge analyses. Langmuir isotherm, pseudo second order kinetic and ion exchange models provided best fit to the experimental data of sorption of metal ions. Maximum sorption capacities of supersorbent HEC-Suc-Na for sorption of heavy metal ions from aqueous solution as calculated by Langmuir isotherm model were found to be 1000, 909.09, 666.6, 588 and 500mgg -1 for Pb(II), Cr(VI), Co(II), Cu(II) and Ni(II), respectively. Competitive sorption of these heavy metal ions was carried out from galvanic and nuclear waste water simulated environment. The negative values of ΔG° and ΔH° indicated spontaneity and exothermic nature of sorption. The sorbent was efficiently regenerated with no significant decrease in sorption capacity after five cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Etching Methods in Metallographic Studies of Duplex Stainless Steel 2205

NASA Astrophysics Data System (ADS)

Kisasoz, A.; Karaaslan, A.; Bayrak, Y.

2017-03-01

Three different etching methods are used to uncover the ferrite-austenite structure and precipitates of secondary phases in stainless steel 22.5% Cr - 5.4% Ni - 3% Mo - 1.3% Mn. The structure is studied under a light microscope. The chemical etching is conducted in a glycerol solution of HNO3, HCl and HF; the electrochemical etching is conducted in solutions of KOH and NaOH.

ONR Tokyo Scientific Bulletin. Volume 5, Number 1, January-March 1980,

DTIC Science & Technology

1980-03-01

alloys studied are in die AI-Zn, Al -Mg, Al -Si. Al - Cu . Cu - Al . and Cu -Fe... alloys Digital processing Measuring N 20. Abstract (cont.) with certain reports also being contributed by visiting stateside scientist. Occasionally a...atomic absorption spectrophotometer with tubes for the determination of Zn, Cu , Pb, Cr, Fe, Mg, Mn, Al , Co, Cd, Si, Ti, Zr, Ga, Au, Ag, Ni, Na, and

Elemental composition of commercial sea cucumbers (holothurians).

PubMed

Wen, J; Hu, C

2010-01-01

Toxic and essential elements in 11 different sea cucumber species were determined and compared with daily intake recommendations and maximum allowed levels. The contents of macro-elements contents in dried sea cucumber samples were found to be 25,000-152,000 mg kg(-1) for Na, 4000-8600 mg kg(-1) for Mg, 1100-5200 mg kg(-1) for K, 15,000-68,000 mg kg(-1) and 36,300-251,000 mg kg(-1) for Cl. Trace element concentrations in dried sea cucumber samples were found to be 11-100 mg kg(-1) for Zn, 41-660 mg kg(-1) for Fe, 3-74 mg kg(-1) for Cu, 1.1-16 mg kg(-1) for Mn, 1.4-3.7 mg kg(-1) for Se, 1.1-9.6 mg kg(-1) for Cr, and 0.3-5.1 mg kg(-1) for Ni. All sea cucumber species were rich sources of Na, Cl, Mg, Ca, Fe, Cu, Se and Cr for human consumption. Regarding contaminants, As, Cd and Pb concentrations in dried sea cucumbers were in the ranges of 1.1-6.1, 0.03-0.06 and 0.11-0.69 mg kg(-1), respectively. Moreover, Hg values of 11 sea cucumbers were below the detection limit (0.01 mg kg(-1)).

The use of olive tree (Olea europaea L.) leaves as a bioindicator for environmental pollution in the Province of Aydın, Turkey.

PubMed

Turan, Dilek; Kocahakimoglu, Cemre; Kavcar, Pınar; Gaygısız, Handan; Atatanir, Levent; Turgut, Cafer; Sofuoglu, Sait C

2011-03-01

In this study, olive tree leaves, collected from 50 sampling sites throughout the Province of Aydın, Turkey, were used to estimate level of pollution by measuring Al, As, B, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn concentrations and calculating pollution factor (PF) values. After sample preparation, collected leaves were microwave digested, and extracts were analyzed by an inductively coupled plasma-mass spectrometer. The maximum PF values were ≥10 for a number of elements ranging from 11-13 (Al, As, Cr, Fe, Mn, Ni) to >100 for Cu, Li, and Na. Urban-rural and roadside-nonroadside concentration comparisons showed that some of the elements (As, Cu, and Pb) were at significantly higher levels on urban and/or roadside sampling sites. Correlations and factor analysis showed that there may be common sources for some elements, which included several soil types and anthropogenic activities. Based on the results of the statistical source apportionment, possible sources were narrowed down with help of the constructed elemental concentration maps. In conclusion, utilization of olive tree leaves for biomonitoring and assessment of environmental pollution was shown to be possible in the Mediterranean region where they are indigenous and cultivated.

Macrominerals and Trace Element Requirements for Beef Cattle.

PubMed

Costa e Silva, Luiz Fernando; Valadares Filho, Sebastião de Campos; Engle, Terry Eugene; Rotta, Polyana Pizzi; Marcondes, Marcos Inácio; Silva, Flávia Adriane Sales; Martins, Edilane Costa; Tokunaga, Arnaldo Taishi

2015-01-01

Eighty-seven Nellore animals were utilized in this study to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral. The net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals.

Application of X-ray photoelectron spectroscopy to the analysis of stainless-steel welding aerosols

NASA Astrophysics Data System (ADS)

Tandon, R. K.; Payling, R.; Chenhall, B. E.; Crisp, P. T.; Ellis, J.; Baker, R. S.

1985-02-01

Aerosol particles ("fume") from manual metal arc welding of stainless steel with E316L-16 electrodes were analysed by X-ray photoelectron spectroscopy. The inherent complexity of the particles required the use of a wide range of experimental techniques. These included IR spectrophotometry, TGA/DTA, XRF, XRD, AAS and electron microprobe analysis. The surface of the fume particles comprised ≈ 50 at% NaF and KF, ≈ 8 at.% soluble (probably K) chromate, ≈ 30 at% SiO 2 and several at.% transition-metal oxides, hydroxides or silicates. The fluorides and chromates were removed by washing to reveal a surface which was predominantly SiO 2 (≈ 60 at%) with the remainder comprising of transition-metal oxides, silicates and fluorides. Approximately 6 at% F remained on the surface of the water-washed particles, presumably as transition-metal fluoro-complexes. The water-soluble fraction of the fume contained K +, Na +, F - and CrO 2-4 ions in the mole ratio 5:5:4:3. When aerosol particles are deposited in lung tissues, water-soluble constituents would be expected to dissolve rapidly. In view of the suspected carcinogenicity of stainless steel welding fume, a bio-medical study of the combined effects of F - and CrO 2-4 ions on lung tissue is warranted.

Macrominerals and Trace Element Requirements for Beef Cattle

PubMed Central

Costa e Silva, Luiz Fernando; de Campos Valadares Filho, Sebastião; Engle, Terry Eugene; Rotta, Polyana Pizzi; Marcondes, Marcos Inácio; Silva, Flávia Adriane Sales; Martins, Edilane Costa; Tokunaga, Arnaldo Taishi

2015-01-01

Eighty-seven Nellore animals were utilized in this study to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral. The net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals. PMID:26657049

Disparities of Selected Metal Levels in the Blood and Scalp Hair of Ischemia Heart Disease Patients and Healthy Subjects.

PubMed

Ilyas, Asim; Shah, Munir H

2017-12-01

Imbalances in the concentrations of trace metals have become an increasingly recognized source of infirmity worldwide particularly in the development of ischemia heart disease (IHD). Present study is intended to analyze the concentrations of Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr, and Zn in the blood and scalp hair of the patients and counterpart controls by flame atomic absorption spectrometry after wet-acid digestion. On the average, Cd, Co, Cr, Fe, K, Li, Mn, Na, and Pb revealed significantly elevated concentrations in the blood of the patients compared with the controls (p < 0.05), whereas mean levels of Ca, Cd, Fe, K, Li, Pb, and Sr in the scalp hair were significantly higher in the patients than the controls (p < 0.05). Most of the metals exhibited noticeable disparities in their concentrations based on gender, abode, dietary/smoking habits, and occupations of both donor groups. The correlation study and multivariate statistical analyses revealed some significantly divergent associations and apportionment of the metals in both donor groups. Overall, comparative variations of the metal contents in blood/scalp hair of the patients were significantly different than the controls; thus, evaluation of trace metals status may be indicative of pathological disorders, such as IHD.

Removal optimization of heavy metals from effluent of sludge dewatering process in oil and gas well drilling by nanofiltration.

PubMed

Hedayatipour, Mostafa; Jaafarzadeh, Neemat; Ahmadmoazzam, Mehdi

2017-12-01

Oil and gas well drilling industries discharge large volumes of contaminated wastewater produced during oil and gas exploration process. In this study, the effect of different operational variables, including temperature, pH and transmembrane pressure on process performance of a commercially available nanofiltration membrane (JCM-1812-50N, USA) for removing Ba, Ni, Cr, NaCl and TDS from produced wastewater by dewatering unit of an oil and gas well drilling industry was evaluated. In optimum experimental conditions (T = 25 °C, P = 170 psi and pH = 4) resulted from Thaguchi method, 85.3, 77.4, 58.5, 79.6 and 56.3% removal efficiencies were achieved for Ba, Ni, Cr, NaCl and TDS, respectively. Also, results from a comparison of the Schuller and Wilcox diagrams revealed that the effluent of the membrane system is usable for drinking water, irrigating and agriculture purposes. Moreover, the process effluent quality showed a scaling feature, according to Langelier saturation index and illustrated that the necessary proceedings should be taken to prevent scaling for industrial application. The nanofiltration membrane process with an acceptable recovery rate of 47.17% represented a good performance in the wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mineralogical studies of the nitrate deposits of Chile. V. Iquiqueite, Na4K3Mg(CrO4)B24O39(OH).12H2O, a new saline mineral.

USGS Publications Warehouse

Ericksen, G.E.; Mrose, M.E.; Marinenko, J.W.; McGee, J.J.

1986-01-01

Iquiqueite (Na4K3Mg(CrO4)B24O39(OH).12H2O, a 11.6369(14), c 30.158(7) A, P31c, Z = 3) occurs as a widespread minor constituent in the nitrate fields of northern Chile. It is particularly abundant in the vicinity of Zapiga, Tarapaca province. Associated minerals include nitratite, halite, nitre, darapskite, blodite, glauberite, dietzeite, bruggenite, ulexite and gypsum. Iquiqueite forms thin, yellow, hexagonal platelets (5-50 mu m in diameter, <5 mu m in thickness) that are disseminated singly or in vermiform aggregates in nitrate ore. Observed forms are c(0001) and m(1010). Cleavage is perfect on (0001) and imperfect on (1010); H. = or <2. D(calc.) 2.05 g/cm3 and measured sp. gr. 2.05 + or - 0.09. The mineral is uniaxial negative, epsilon 1.447(2), omega 1.502(2). The XRD pattern has the six strongest lines 3.02(100), 2.856(100), 10.11(85), 6.04(85), 3.28(85), 3.22(85) A. The name is for the city of Iquique, Chile.-J.A.Z.

Dynamics of multiple elements in fast decomposing vegetable residues.

PubMed

Cao, Chun; Liu, Si-Qi; Ma, Zhen-Bang; Lin, Yun; Su, Qiong; Chen, Huan; Wang, Jun-Jian

2018-03-01

Litter decomposition regulates the cycling of nutrients and toxicants but is poorly studied in farmlands. To understand the unavoidable in-situ decomposition process, we quantified the dynamics of C, H, N, As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, and Zn during a 180-d decomposition study in leafy lettuce (Lactuca sativa var. longifoliaf) and rape (Brassica chinensis) residues in a wastewater-irrigated farmland in northwestern China. Different from most studied natural ecosystems, the managed vegetable farmland had a much faster litter decomposition rate (half-life of 18-60d), and interestingly, faster decomposition of roots relative to leaves for both the vegetables. Faster root decomposition can be explained by the initial biochemical composition (more O-alkyl C and less alkyl and aromatic C) but not the C/N stoichiometry. Multi-element dynamics varied greatly, with C, H, N, K, and Na being highly released (remaining proportion<20%), Ca, Cd, Cr, Mg, Ni, and Zn released, and As, Cu, Fe, Hg, Mn, and Pb possibly accumulated. Although vegetable residues serve as temporary sinks of some metal(loid)s, their fast decomposition, particularly for the O-alkyl-C-rich leafy-lettuce roots, suggest that toxic metal(loid)s can be released from residues, which therefore become secondary pollution sources. Copyright © 2017 Elsevier B.V. All rights reserved.

Instrumental and bio-monitoring of heavy metal and nanoparticle emissions from diesel engine exhaust in controlled environment.

PubMed

Giordano, Simonetta; Adamo, Paola; Spagnuolo, Valeria; Vaglieco, Bianca Maria

2010-01-01

In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of light-duty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO2, 02, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7-54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of Al and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in Al, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.

Ferrate treatment for removing chromium from high-level radioactive tank waste.

PubMed

Sylvester, P; Rutherford, L A; Gonzalez-Martin, A; Kim, J; Rapko, B M; Lumetta, G J

2001-01-01

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. This method could be generally applicable to removing chromium from chromium-contaminated solids, when coupled with a subsequent reduction of the separated chromate back to chromium(III). The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(II) molar ratio, but the chromium removal tends to level out for Fe(VI)/ Cr(III) greaterthan 10. Increasingtemperature leadsto better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be disposed as low-activity waste.

Electro-enhanced hollow fiber membrane liquid phase microextraction of Cr(VI) oxoanions in drinking water samples.

PubMed

Chanthasakda, Nattaporn; Nitiyanontakit, Sira; Varanusupakul, Pakorn

2016-02-01

Hollow fiber membrane liquid phase microextraction (HF-LPME) of metal oxoanions was studied using an ionic carrier enhanced by the application of an electric field (electro-enhanced HF-LPME). The Cr(VI) oxoanion was used as the model. The transportation of Cr(VI) oxoanions across the supported liquid membrane (SLM) was explored via the ion-exchange process and electrokinetic migration. The type of SLM, type of acceptor solution, extraction time, electric potential, and stirring rate were investigated and optimized using MilliQ water. Electro-enhanced HF-LPME provided a much higher enrichment factor compared to conventional HF-LPME (no electric potential) for the same extraction time. A mixture of an anion exchange carrier (methyltrialkyl-ammonium chloride, Aliquat 336) in the SLM facilitated the transportation of Cr(VI) oxoanions. The SLM that gave the best performance was 1-heptanol mixed with 5% Aliquat 336 with 1M NaOH as the acceptor. Linearity was obtained in the working range of 3-15 µg L(-1) Cr(VI) (R(2)>0.99) at 30 V with a 5 min extraction time. The limit of detection was below 5 µg L(-1). The relative standard deviation was less than 12%. The method was applied to drinking water samples. The recoveries of spiked Cr(VI) in drinking water samples were in the range of 96-101% based on the matrix-matched calibration curves. The method was limited to samples containing low levels of ions due to the occurrence of electrolysis. The type of SLM, particularly regarding its resistance, should be tuned to control this problematic phenomenon. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface microstructure and high temperature corrosion resistance of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam

NASA Astrophysics Data System (ADS)

Hao, Shengzhi; Zhao, Limin; He, Dongyun

2013-10-01

The surface microstructure of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam (HCPEB) with long pulse duration of 200 μs was characterized by using optical microscopy, scanning electron microscopy and X-ray diffractometry. The distribution of chemical composition in modified surface layer was measured with electron probe micro-analyzer. The high temperature corrosion resistance of FeCrAl coating was tested in a saturated Na2SO4 and K2SO4 solution at 650 °C. After HCPEB irradiation, the coarse surface of arc-sprayed coating was changed as discrete bulged nodules with smooth and compact appearance. When using low energy density of 20 J/cm2, the surface modified layer was continuous entirely with an average melting depth of ˜30 μm. In the surface remelted layer, Fe and Cr elements gave a uniform distribution, while Al and O elements agglomerated particularly at the concave part between nodule structures to form α-Al2O3 phase. After high temperature corrosion tests, the FeCrAl coating treated with HCPEB of 20 J/cm2 remained a glossy surface with weight increment of ˜51 mg/cm2, decreased by 20% as compared to the initial sample. With the increasing energy density of HCPEB irradiation, the integrity of surface modified layer got segmented due to the formation of larger bulged nodules and cracks at the concave parts. For the HCPEB irradiation of 40 J/cm2, the high temperature corrosion resistance of FeCrAl coating was deteriorated drastically.

Prefrontal N-acetylaspartate is strongly associated with memory performance in (abstinent) ecstasy users: preliminary report.

PubMed

Reneman, L; Majoie, C B; Schmand, B; van den Brink, W; den Heeten, G J

2001-10-01

3,4-methylenedioxymethamphetamine (MDMA or "Ecstasy") is known to damage brain serotonin neurons in animals and possibly humans. Because serotonergic damage may adversely affect memory, we compared verbal memory function between MDMA users and MDMA-naïve control subjects and evaluated the relationship between verbal memory function and neuronal dysfunction in the MDMA users. An auditory verbal memory task (Rey Auditory Verbal Learning Test) was used to study eight abstinent MDMA users and seven control subjects. In addition 1H-MRS was used in different brain regions of all MDMA users to measure N-acetylaspartate/creatine (NAA/Cr) ratios, a marker for neuronal viability. The MDMA users recalled significantly fewer words than control subjects on delayed (p =.03) but not immediate recall (p =.08). In MDMA users, delayed memory function was strongly associated with NAA/Cr only in the prefrontal cortex (R(2) =.76, p =.01). Greater decrements in memory function predicted lower NAA/Cr levels-and by inference greater neuronal dysfunction-in the prefrontal cortex of MDMA users.

A Synthetic Calcite Standard for Determination of Relative Mn/Cr Sensitivity Factor

NASA Astrophysics Data System (ADS)

Fujiya, W.; Ichimura, K.; Takahata, N.; Sugiura, N.; Sano, Y.

2009-12-01

Primitive chondrites which suffered from aqueous alteration often contain carbonates such as calcites, dolomites and breunnerites. 53Mn-53Cr decay system (half-life: 3.7 Myr) is applicable to dating their precipitation and many authors have measured their Mn-Cr ages using the SIMS. However, the relative Mn/Cr sensitivity factor: RSF (measured Mn+/Cr+ ratio divided by the true ratio) is not well established due to the absence of suitable standards, therefore the ages have systematic uncertainties. We prepared a synthetic Mn and Cr bearing calcite to evaluate the Mn/Cr RSF. Here we report the technical details of preparation for the standard and its Mn/Cr RSF. We also measured the Mn/Cr RSF of San Carlos olivine which is often assumed to be the same as that of a carbonate, and compared it with that of our synthetic calcite. The Cr-bearing calcite was produced in a N2 filled closed system by the reaction Ca2+ + CO32- = CaCO3 in an aqueous solution. The reaction proceeded by continuous addition of ammonium carbonate vapor to the solution. The crystal size of the calcite was ~300 μm. A small amount of hydrazine was added to the solution in order to keep chromous ion from oxidation. Mn and Cr concentrations in the calcite grains were determined by the SEM-EDS. A weak, defocused beam was used due to prevent electron beam damage. In a spherical grain, radial zoning of Mn and Cr concentrations occur and they decrease towards the periphery. At the center of the grains, Mn and Cr concentrations are ~0.5 atomic % and the values of the Mn/Cr ratios are relatively constant. The Mn/Cr RSF was determined with the CAMECA NanoSIMS 50 at Ocean Research Institute of Univ. of Tokyo. A primary O- beam of ~1 nA and 5 μm diameter was used. 43Ca+, 52Cr+, 53Cr+ and 55Mn+ ions were analyzed in a combined peak-jumping/multi-detection mode. The total measurement time was typically ~20 minutes. The measurements were started after presputtering of 15 minutes. The mass resolution power was ~3500, sufficient to resolve all relevant isobaric interferences. Several points near the center of calcite grains with constant Mn and Cr concentrations were measured. As for San Carlos olivine, a primary beam was rastered over 20 x 20 μm2 areas. Signals of all ions decreased with time during the measurements. The 55Mn/52Cr RSF also decreased with time. Initially it was ~0.7-0.8, and approached to a nearly constant value of ~0.5-0.6 after ~20 minutes. 53Cr+/52Cr+ isotopic ratio was 0.1105 ± 0.0002 (1σ), not dependent on time and space. This value corresponds to ~-26 permil fractionation from the reference value. On the other hand, the RSF of San Carlos olivine was found to be ~0.9, consistent with previous studies. The RSF of our calcite is significantly lower than the values used in previous studies and the RSF of San Carlos olivine measured in this study. This implies that Mn-Cr ages for carbonates obtained in previous studies may have systematic biases (~3 Myr).

Nuclear Decay Data for the International Reactor Dosimetry Library for Fission and Fusion (IRDFF): Updated Evaluations of the Half-Lives and Gamma Ray Intensities

NASA Astrophysics Data System (ADS)

Chechev, Valery P.; Kuzmenko, Nikolay K.

2016-02-01

Updated evaluations of the half-lives and prominent gamma ray intensities have been presented for 20 radionuclides - dosimetry reaction residuals. The new values of these decay characteristics recommended for the IRDFF library were obtained using the approaches and methodology adopted by the working group of the Decay Data Evaluation Project (DDEP) cooperation. The experimental data published up to 2014 were taken into account in updated evaluations. The list of radionuclides includes 3H, 18F, 22Na, 24Na, 46Sc, 51Cr, 54Mn, 59Fe, 57Co, 60Co, 57Ni, 64Cu, 88Y, 132Te, 131I, 140Ba, 140La, 141Ce, 182Ta, 198Au.

Passive Films, Surface Structure and Stress Corrosion and Crevice Corrosion Susceptibility. Part I. A Qualitative Ellipsometric-Electrochemical Approach for the Study of Film Growth under Organic Coatings. Part II. Hydrogen Interactions with Stressed Titanium-Palladium Alloys and Stressed Vanadium Explored with Field Ion Microscopy.

DTIC Science & Technology

1980-08-01

vs. time for Fe with collodion in 0.05 N NaCl. 8. A, 6 p, pH and 0Fe vs. time for Fe with collodion and CrO 4 " 2 islands in 0.05 N NaCl. REFERENCES...hydrogen embrittlement with the field ion microscope, and to compare the results with those previously obtained with pure titanium [ 4 ]. 2.2. Specimen...percent pure, and was used in the previous field ion microscopy study of titanium [ 4 ], where it was found that strain annealing titanium wire markedly

Spatial and temporal characterization of trace elements and nutrients in the Rawal Lake Reservoir, Pakistan using multivariate analysis techniques.

PubMed

Malik, Riffat Naseem; Nadeem, Muhammad

2011-12-01

Rawal Lake Reservoir is renowned for its ecological significance and is the sole source of drinking water of the third largest city of Pakistan. However, fish kill in recent years and anthropogenic impacts from human-related activities in its catchment area have resulted in deterioration of its surface water quality. This study aims to characterize spatial and temporal variations in surface water quality, identify contaminant sources, and compare their levels with quality guidelines. Surface water samples were collected from 10 sites and analyzed for 27 physicochemical parameters for a period of 2 years on a seasonal basis. Concentration of metals in surface water in pre-monsoon were in the order: Fe > Mg > Ca > Mn > Zn > Ni > Cr > Cu > Co > Pb, whereas in post-monsoon, the order of elemental concentrations was: Ca > Mg > Na > Fe > K > Zn > Cr > Li > Pb > Co > Ni > Cu > Mn > Cd. Metals (Ni, Fe, Zn, and Ca), pH, electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), and nutrients (PO (4) (3-) , NO(3)-N, and SO (4) (2-) ) were measured higher in pre-monsoon, whereas concentration of Cu, Mn, Cr, Co, Pb, Cd, K, Na, Mg, Li, Cl(-), and NH(4)-N were recorded higher in post-monsoon. Results highlighted serious metal pollution of surface water. Mean concentration of Zn, Cd, Ni, Cu, Fe, Cr, and Pb in both seasons and Mn in post-monsoon were well above the permissible level of surface water quality criteria. Results stress the dire need to reduce heavy-metal input into the lake basin and suggest that heavy-metal contamination should be considered as an integral part of future planning and management strategies for restoration of water quality of the lake reservoir.

RCoronae Borealis at the 2003 light minimum

NASA Astrophysics Data System (ADS)

Kameswara Rao, N.; Lambert, David L.; Shetrone, Matthew D.

2006-08-01

A set of five high-resolution optical spectra of R CrB obtained in 2003 March is discussed. At the time of the first spectrum (March 8), the star was at V = 12.6, a decline of more than six magnitudes. By March 31, the date of the last observation, the star at V = 9.3 was on the recovery to maximum light (V = 6). The 2003 spectra are compared with the extensive collection of spectra from the 1995-1996 minimum presented previously. Spectroscopic features common to the two minima include the familiar ones also seen in spectra of other R Coronae Borealis stars (RCBs) in decline: sharp emission lines of neutral and singly ionized atoms, broad emission lines including HeI, [NII] 6583 Å, Na D and CaII H & K lines, and blueshifted absorption lines of Na D, and KI resonance lines. Prominent differences between the 2003 and 1995-1996 spectra are seen. The broad Na D and Ca H & K lines in 2003 and 1995-1996 are centred approximately on the mean stellar velocity. The 2003 profiles are fit by a single Gaussian, but in 1995-1996 two Gaussians separated by about 200 km s-1 were required. However, the HeI broad emission lines are fit by a single Gaussian at all times; the emitting He and Na-Ca atoms are probably not colocated. The C2 Phillips 2-0 lines were detected as sharp absorption lines and the C2 Swan band lines as sharp emission lines in 2003, but in 1995-1996 the Swan band emission lines were broad and the Phillips lines were undetected. The 2003 spectra show CI sharp emission lines at minimum light with a velocity changing in 5 d by about 20 km s-1 when the velocity of `metal' sharp lines is unchanged; the CI emission may arise from shock-heated gas. Reexamination of spectra obtained at maximum light in 1995 shows extended blue wings to strong lines with the extension dependent on a line's lower excitation potential; this is the signature of a stellar wind, also revealed by published observations of the HeI 10830 Å line at maximum light. Changes in the cores of the resonance lines of AlI and Na D (variable blueshifts) and the CaII infrared (IR) lines (variable blueshifts and redshifts) suggest complex flow patterns near the photosphere. The spectroscopic differences at the two mimima show the importance of continued scrutiny of the declines of R CrB (and other RCBs). Thorough understanding of the outer atmosphere and circumstellar regions of R CrB will require such continued scrutiny. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München and Georg-August-Universität Göttingen. E-mail: dll@anchor.as.utexas.edu (DLL)

Origin, speciation, and fluxes of trace-element gases at Augustine volcano, Alaska: Insights into magma degassing and fumarolic processes

NASA Astrophysics Data System (ADS)

Symonds, Robert B.; Reed, Mark H.; Rose, William I.

1992-02-01

Thermochemical modeling predicts that trace elements in the Augustine gas are transported from near-surface magma as simple chloride (NaCl, KCl, FeCl 2, ZnCl 2, PbCl 2, CuCl, SbCl 3, LiCl, MnCl 2, NiCl 2, BiCl, SrCl 2), oxychloride (MoO 2Cl 2), sulfide (AsS), and elemental (Cd) gas species. However, Si, Ca, Al, Mg, Ti, V, and Cr are actually more concentrated in solids, beta-quartz (SiO 2), wollastonite (CaSiO 3), anorthite (CaAl 2Si 2O 8), diopside (CaMgSi 2O 6), sphene (CaTiSiO 5), V 2O 3(c), and Cr 2O 3(c), respectively, than in their most abundant gaseous species, SiF 4, CaCl 2, AlF 2O, MgCl 2 TiCl 4, VOCl 3, and CrO 2Cl 2. These computed solids are not degassing products, but reflect contaminants in our gas condensates or possible problems with our modeling due to "missing" gas species in the thermochemical data base. Using the calculated distribution of gas species and the COSPEC SO 2 fluxes, we have estimated the emission rates for many species (e.g., COS, NaCl, KCl, HBr, AsS, CuCl). Such forecasts could be useful to evaluate the effects of these trace species on atmospheric chemistry. Because of the high volatility of metal chlorides (e.g., FeCl 2, NaCl, KCl, MnCl 2, CuCl), the extremely HCl-rich Augustine volcanic gases are favorable for transporting metals from magma. Thermochemical modeling shows that equilibrium degassing of magma near 870°C can account for the concentrations of Fe, Na, K, Mn, Cu, Ni and part of the Mg in the gases escaping from the dome fumaroles on the 1986 lava dome. These calculations also explain why gases escaping from the lower temperature but highly oxidized moat vents on the 1976 lava dome should transport less Fe, Na, K, Mn and Ni, but more Cu; oxidation may also account for the larger concentrations of Zn and Mo in the moat gases. Nonvolatile elements (e.g., Al, Ca, Ti, Si) in the gas condensates came from eroded rock particles that dissolved in our samples or, for Si, from contamination from the silica sampling tube. Only a very small amount of rock contamination occurred (water/rock ratios between 10 4 and 10 6). Erosion is more prevalent in the pyroclastic flow fumaroles than in the summit vents, reflecting physical differences in the fumarole walls: ash vs. lava. Trace element contents of volcanic gases show enormous variability because of differences in the intensive parameters of degassing magma and variable amounts of wall rock erosion in volcanic fumaroles.

Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

NASA Astrophysics Data System (ADS)

Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

2013-06-01

This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

Zirconium-based metal organic frameworks loaded on polyurethane foam membrane for simultaneous removal of dyes with different charges.

PubMed

Li, Juan; Gong, Ji-Lai; Zeng, Guang-Ming; Zhang, Peng; Song, Biao; Cao, Wei-Cheng; Liu, Hong-Yu; Huan, Shuang-Yan

2018-10-01

Treating dye wastewater by membrane filtration technology has received much attention from researchers all over the world, however, current studies mainly focused on the removal of singly charged dyes but actual wastewater usually contains dyes with different charges. In this study, the removal of neutral, cationic and anionic dyes in binary or ternary systems was conducted by using zirconium-based metal organic frameworks loaded on polyurethane foam (Zr-MOFs-PUF) membrane. The Zr-MOFs-PUF membrane was fabricated by an in-situ hydrothermal synthesis approach and a hot-pressing process. Neutrally charged Rhodamine B (RB), positively charged Methylene blue (MB), and negatively charged Congo red (CR) were chosen as model pollutants for investigating filtration performance of the membrane. The results of filtration experiments showed that the Zr-MOFs-PUF membrane could simultaneously remove RB, MB, and CR not only from their binary system including RB/MB, RB/CR, and MB/CR mixtures, but also from RB/MB/CR ternary system. The removal of dyes by Zr-MOFs-PUF membrane was mainly attributed to the electrostatic interactions, hydrogen bond interaction, and Lewis acid-base interactions between the membrane and dye molecules. The maximum removal efficiencies by Zr-MOFs-PUF membrane were 98.80% for RB at pH ≈ 7, 97.57% for MB at pH ≈ 9, and 87.39% for CR at pH ≈ 3. Additionally, when the NaCl concentration reached 0.5 mol/L in single dye solutions, the removal efficiencies of RB, MB, and CR by Zr-MOFs-PUF membrane were 93.08%, 79.52%, and 97.82%, respectively. All the results suggested that the as-prepared Zr-MOFs-PUF membrane has great potential in practical treatment of dye wastewater. Copyright © 2018 Elsevier Inc. All rights reserved.

Assessment of trace metal contamination in stream sediments of the Tuul River, Mongolia

NASA Astrophysics Data System (ADS)

Dalai, B.

2011-12-01

Thirty four sediment samples were collected in Ulaanbaatar basin, along the Tuul River which is the main source of water for the capital city Ulaanbaatar, Mongolia. The catchment can be divided three parts (upper, middle, and lower) according to the extent of urbanization. The upper part of the river basin is comparatively less affected by human activity and it can be represent the natural background condition. The middle part is the urban area of Ulaanbaatar and lower part extends SW of the end of the urban area mostly used for agriculture and farming activity. The present study focused on the levels of potentially toxic metals such as As, Pb, Zn, Cu, Ni and Cr in order to assess the extent of environmental pollution and to discuss the origin of these contaminants in sediments of the Tuul River using X-ray fluorescence analyses. Metal concentrations in the sediments are discussed by comparison with average Upper Continental Crust values (UCC) and ecological risk assessment by reference to sediment quality guidelines (SQG). The results showed thet average abundances of metals are measurable contrast between upper, middle and lower parts of the river. The Upper part and its surrounding area's sediment signature indicated that more depletion comparatively other parts (Pb, Zn, Cu, Ni and Cr), whereas enrichment sign did not detect. However, among the Upper part sediments, two samples (NA1 and NA2) enriched with trace metals which sampled from Nalaikh area were significantly affected by coal mining activity. Most metals are (As, Pb, Zn, Cu and Ni) higher in the middle part (within the city) than the upper and lower part due to the urban activities. The small tributaries such as Selbe, Uliastai, Gachuurt and Tolgoit were significantly affected by urban activities and highest values are detected from them. Lower part significantly enriched with Cr (av 98 ppm). Highest concentration of Cr (183 ppm) was at Shuvuu which is receiving point of domestic and industrial wastewater discharge. However all three parts show depletion in some chalcophile and HFSE elements (Cu, Ni, Cr, Sr, Nb, Zr, Th, Sc). This depletion of elements relative to UCC suggest that the river sediments were derived from a highly felsic crustal source. The assessment of ecological risk assessment result showed that adverse aquatic biological effects caused by As and Cr. While, concentration of Pb, Zn, Cu and Ni are generally below their respective Threshold effect level (TEL), in middle part reaches to reach values bordering on the Probable effect level (PEL). This indicated that anthropogenic contribution in the urban areas, increasing values above a naturally low regional background.

Mg2+ ion effect on conformational equilibrium of poly A . 2 poly U and poly A poly U in aqueous solutions.

PubMed

Sorokin, Victor A; Valeev, Vladimir A; Gladchenko, Galina O; Degtiar, Marina V; Karachevtsev, Victor A; Blagoi, Yuri P

2003-01-15

Differential UV spectroscopy and thermal denaturation were used to study the Mg(2+) ion effect on the conformational equilibrium in poly A.2 poly U (A2U) and poly A . poly U (AU) solutions at low (0.01 M Na(+)) and high (0.1 M Na(+)) ionic strengths. Four complete phase diagrams were obtained for Mg(2+)-polynucleotide complexes in ranges of temperatures 20-96 degrees C and concentrations (10(-5)-10(-2)) M Mg(2+). Three of them have a 'critical' point at which the type of the conformational transition changes. The value of the 'critical' concentration ([Mg(t)(2+)](cr)=(4.5+/-1.0) x 10(-5) M) is nearly independent of the initial conformation of polynucleotides (AU, A2U) and of Na(+) contents in the solution. Such a value is observed for Ni(2+) ions too. The phase diagram of the (A2U+Mg(2+)) complex with 0.01 M Na(+) has no 'critical' point: temperatures of (3-->2) and (2-->1) transitions increase in the whole Mg(2+) range. In (AU+Mg(2+)) phase diagram at 0.01 M Na(+) the temperature interval in which triple helices are formed and destroyed is several times larger than at 0.1 M Na(+). Using the ligand theory, a qualitative thermodynamic analysis of the phase diagrams was performed.

A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag.

PubMed

Dean, Philip A W; Craig, Don; Dance, Ian; Russell, Vanessa; Scudder, Marcia

2004-01-26

Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single crystals, this reversible dehydration-hydration occurs without visually evident crystal change, but with loss of mechanical strength. We postulate a general mechanism for transport of water molecules along the channels, associated with local partial collapses of the channel framework, with concomitant bending but little breaking of the host Ag-O and Cr-O bonds, which is readily reversed.

Incremental Sampling Methodology (ISM) for Metallic Residues

DTIC Science & Technology

2013-08-01

Deviation (also %RSD) Sb Antimony Sn Tin Sr Strontium STD Standard Deviation ERDC TR-13-5 x SU Sampling Unit Ti Titanium UCL Upper Confidence Limit...Ce), chromium (Cr), Cu, Fe, Pb, mag- nesium (Mg), Mn, potassium (K), sodium (Na), strontium (Sr), titanium (Ti), W, zirconium (Zr), and Zn (Clausen...wastes. A proposed alternative to EPA SW 846 Method 3050. Environmental Science and Technology 23: 89 −900. Matzke, B., N. Hassig, J. Wilson, R. Gilber

Photographic Processing Interpretation Facility Wastewater Conceptual Treatment Design.

DTIC Science & Technology

1983-03-01

Total Chromium (Cr) - - - ɘ.05 - Copper (Cu) - - - ɘ.05 - Iron (Fe) - - - - - Manganese (Mn) - - - ɘ.03 - Mercury (Hg) - - - ɘ.004 - Potassium (K...8.3 - Silver (Ag) 2.2 7.0 17 0.15 2.2 Sodium (Na) - - - 8.2 - Zinc (Zn) - - - 0.12 - Biochemical Oxygen " Demand (BOD_) - - - 40 - Sulfate (SO...nonconventional pollutants include boron, dissolved sol i halides, iron, ammonia, nitrogen, phenols, sulfate and TOC. ,P,, 99 percent of the 11,000

Physicochemical characterization of cactus pads from Opuntia dillenii and Opuntia ficus indica.

PubMed

Méndez, Lorena Pérez; Flores, Fidel Tejera; Martín, Jacinto Darias; Rodríguez Rodríguez, Elena M; Díaz Romero, Carlos

2015-12-01

Physicochemical characteristics (weight, length, width, thickness, moisture, Brix degree, total fiber, protein, ash, pH, acidity, ascorbic acid, total phenolic compounds, P, Na, K, Ca, Mg, Fe, Cu, Zn, Mn and Cr) were determined in cactus pads from Opuntia dillenii and Opuntia ficus indica. The physicochemical characteristics of both species were clearly different. There were important differences between the orange and green fruit pulp of O. ficus indica; the cactus pads of O. dillenii could be differentiated according to the region (North and South). Consumption of cactus pads contributes to the intake of dietary fiber, total phenolic compounds, K, Mg, Mn and Cr. Applying factor and/or discriminant analysis, the cactus pad samples were clearly differentiated according to the species, the fruit pulp color and production region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Long-Term Experimental Determination of Solubilities of Micro-Crystalline Nd(III) Hydroxide in High Ionic Strength Solutions: Applications to Nuclear Waste Management [A Pitzer Model for Am(III)/Nd(III) hydroxide solubility in NaCl-H 2O at 298.15 K to high ionic strengths: Experimental validation and model applications

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

Xiong, Yongliang; Kirkes, Leslie Dawn; Marrs, Cassandra

In this paper, the experimental results from long-term solubility experiments on micro crystalline neodymium hydroxide, Nd(OH) 3(micro cr), in high ionic strength solutions at 298.15 K under well-constrained conditions are presented. The starting material was synthesized according to a well-established method in the literature. In contrast with the previous studies in which hydrogen ion concentrations in experiments were adjusted with addition of either an acid or a base, the hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH) 3(micro cr), avoiding the possibility of phase change.

Long-Term Experimental Determination of Solubilities of Micro-Crystalline Nd(III) Hydroxide in High Ionic Strength Solutions: Applications to Nuclear Waste Management [A Pitzer Model for Am(III)/Nd(III) hydroxide solubility in NaCl-H 2O at 298.15 K to high ionic strengths: Experimental validation and model applications

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie Dawn; Marrs, Cassandra

2017-12-01

In this paper, the experimental results from long-term solubility experiments on micro crystalline neodymium hydroxide, Nd(OH) 3(micro cr), in high ionic strength solutions at 298.15 K under well-constrained conditions are presented. The starting material was synthesized according to a well-established method in the literature. In contrast with the previous studies in which hydrogen ion concentrations in experiments were adjusted with addition of either an acid or a base, the hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH) 3(micro cr), avoiding the possibility of phase change.

Electrochemical screening of organic and inorganic inhibitors for the corrosion of ASTM A-470 steel in concentrated sodium hydroxide solution

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

Moccari, A.; MacDonald, D.D.

The corrosion of ASTM A-470 turbine disk steel in concentrated sodium hydroxide solution (10 mol/kg) containing sodium silicate, sodium dihydrogen phosphate, sodium chromate, aniline and some of its derivatives, tannic acid, L-(-)-phenylalanine (aminopropionic acid) and octadecylamine as potential inhibitors has been studied using the potentiodynamic, AC impedance, and Tafel extrapolation techniques. All tests were performed at 115 + or - 2 C. The anodic and cathodic polarization data show that aniline and its derivatives, L-(-)-phenylalanine, NaH/sub 2/PO/sub 4/, Na/sub 2/SiO/sub 3/, and Na/sub 2/CrO/sub 4/ inhibit the anodic process, whereas tannic acid inhibits the cathodic reaction. Octadecylamine was found tomore » inhibit both the anodic and cathodic processes. The mechanisms of inhibition for some of these compounds have been inferred from the wide band width frequency dispersions of the interfacial impedance.« less

Cr(VI) transport via a supported ionic liquid membrane containing CYPHOS IL101 as carrier: system analysis and optimization through experimental design strategies.

PubMed

Rodríguez de San Miguel, Eduardo; Vital, Xóchitl; de Gyves, Josefina

2014-05-30

Chromium(VI) transport through a supported liquid membrane (SLM) system containing the commercial ionic liquid CYPHOS IL101 as carrier was studied. A reducing stripping phase was used as a mean to increase recovery and to simultaneously transform Cr(VI) into a less toxic residue for disposal or reuse. General functions which describe the time-depending evolution of the metal fractions in the cell compartments were defined and used in data evaluation. An experimental design strategy, using factorial and central-composite design matrices, was applied to assess the influence of the extractant, NaOH and citrate concentrations in the different phases, while a desirability function scheme allowed the synchronized optimization of depletion and recovery of the analyte. The mechanism for chromium permeation was analyzed and discussed to contribute to the understanding of the transfer process. The influence of metal concentration was evaluated as well. The presence of different interfering ions (Ca(2+), Al(3+), NO3(-), SO4(2-), and Cl(-)) at several Cr(VI): interfering ion ratios was studied through the use of a Plackett and Burman experimental design matrix. Under optimized conditions 90% of recovery was obtained from a feed solution containing 7mgL(-1) of Cr(VI) in 0.01moldm(-3) HCl medium after 5h of pertraction. Copyright © 2014 Elsevier B.V. All rights reserved.

An improved method for high precision measurement of chromium isotopes using double spike MC-ICP-MS

NASA Astrophysics Data System (ADS)

Zhu, J.; Wu, G. L.; Wang, X.; Zhang, L. X.; Han, G.

2017-12-01

Chormium(Cr) isotopes have been used to trace pollution processes and reconstruct paleo-redox conditions. However, the precise determination of Cr isotopes has still been challenged due to difficulties in purifying Cr from samples with low Cr content and complex matrices. Here we report an improved four-step column chromatographic procedure to separate Cr from matrix elements. Firstly, Cr in sample solution was mixed with 50Cr-54Cr double spike (the optimized 54Crspike/52Crsample = 0.4 and (50Cr/54Cr)spike = 1.3:1) was completely converted into Cr (III) in 8.5mol/L HCl and loaded onto 2ml of AG50W-X8(200-400m) resin conditioned with 11 mol/L HCl. The 2.65ml of eluent was adjusted to 4.5ml of 6mol/L HCl and immediately loaded onto a Bio-Rad column filled with 2ml of AG1-X8 anion resin (100-200m). These two steps can remove at least 99% of Ca, Fe and most matrix elements. Secondly, the 7.5ml of eluent was dried down and dissolved in 0.1ml of 0.5mol/L HNO3.before adding 2ml 4mol/L HF, which was then loaded onto 1ml of AG1-X8 anion resin (100-200m) to remove Ti and V. Finally, sample was dissolved in 0.1ml of 0.5 mol/L HNO3 and oxidized by 0.5mL 0.2 mol/L (NH4)2S2O8 and 4.4mL H2O, which was then centrifuged to remove Mn oxide, and supernatant was loaded onto AG1-X8 resin to remove SO42-, Ni, Al, Na and some Mg using 8ml H2O and 3ml 2mol/L HCl. Cr was eluted by 2 mol/L HNO3 containing 5% H2O2 and the dried Cr was dissolved in 3% HNO3for isotopic analysis. The total yield to Cr is great than 80% even for samples with low Cr content. Chromium isotopes was measured on a Neptune plus MC-ICP-MS in China University of Geosciences(Beijing). Using our improved method, the δ53/52CrSRM979 values of USGS reference materials BHVO-2, BCR-2 and SGR-1b are -0.12±0.06‰(n=15), -0.09±0.06‰ (n=5), and 0.30±0.06‰ (n=12), respectively, which agree well with previously reported values. The δ53/52CrSRM979 of carbonaceous shale CP0-1 and CP0-12 collected from Hubei, China are 2.05±0.08‰ (n=3) and 2.08±0.07‰ (n=3), respectively, identical to 2.17±0.08‰ and 2.14±0.08‰ determined at the Department of Geology, UIUC. This work was supported by the National Key Basic Research Program of China (2014CB238903) and the National Natural Science Foundation of China (41473028, 41273029).

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.

Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

NASA Astrophysics Data System (ADS)

Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

2016-09-01

Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal peridotites and MORB from very slow-spreading ridges. Instead, the distinctive compositions of abyssal peridotites and MORB from very slow-spreading ridges could result from the presence of a thick lithospheric lid, leading to a lower average degree of melting, and a higher contribution to melting from more fertile mantle lithologies. Alternatively, spreading rate influences the thermal structure of the upper mantle such that the mantle beneath very slow-spreading ridges is cooler.

The measurement of radiation exposure of astronauts by radiochemical techniques

NASA Technical Reports Server (NTRS)

Brodzinski, R. L.

1972-01-01

Cosmic radiation doses to the crews of the Apollo 14, 15, and 16 missions of 142 + or - 80, 340 + or - 80, and 210 + or - 130 mR respectively were calculated from the specific activities of Na-22 and Na-24 in the postflight urine specimens of the astronauts. The specific activity of Fe-59 was higher in the urine than in the feces of the Apollo 14 and 15 astronauts, and a possible explanation is given. The concentrations of K-40, K-42, Cr-51, Co-60, and Cs-137 in the urine are also reported for these astronauts. The radiation doses received by pilots and navigators flying high altitude missions during the solar flare of March 27 to 30, 1972 were calculated from the specific activity of Na-24 in their urine. These values are compared with the expected radiation dose calculated from the known shape and intensity of the proton spectrum and demonstrate the magnitude of atmospheric shielding. The concentrations of Na, K, Rb, Cs, Fe, Co, Ag, Zn, Hg, As, Sb, Se, and Br were measured in the urine specimens from the Apollo 14 and 15 astronauts by neutron activation analysis. The mercury and arsenic levels were much higher than expected.

Chemistry of impact events on Mercury

NASA Astrophysics Data System (ADS)

Berezhnoy, Alexey A.

2018-01-01

Based on the equilibrium thermochemical approach and quenching theory, formation of molecules and dust grains in impact-produced clouds formed after collisions between meteoroids and Mercury is considered. Based on observations of Al, Fe, and Mn atoms in the exosphere of Mercury and new results of studies of the elemental composition of the surface of Mercury, quenching temperatures and pressures of main chemical reactions and condensation of dust particles were estimated. The behavior of the main Na-, K-, Ca-, Fe-, Al-, Mn-, Mg-, Si-, Ti, Ni-, Cr-, Co, Zn-, O-, H-, S-, C-, Cl-, N-, and P-containing species delivered to the Hermean exosphere during meteoroid impacts was studied. The importance of meteoroid bombardment as a source of Na, K, Ca, Fe, Al, Mn, Mg, and O atoms in the exosphere of Mercury is discussed.

Evidence for Metabolic Hypothalamo-Amygdala Dysfunction in Narcolepsy

PubMed Central

Poryazova, Rositsa; Schnepf, Betina; Werth, Esther; Khatami, Ramin; Dydak, Ulrike; Meier, Dieter; Boesiger, Peter; Bassetti, Claudio L.

2009-01-01

Study Objectives: Proton resonance spectroscopy (1H-MRS) allows noninvasive chemical tissue analysis in the living brain. As neuronal loss and gliosis have been described in narcolepsy, metabolites of primary interest are N-acetylaspartate (NAA), a marker of neuronal integrity and myo-Inositol (mI), a glial marker and second messenger involved in the regulation of intracellular calcium. One 1H-MRS study in narcolepsy found no metabolic changes in the pontomedullary junction. Another study showed a reduction in NAA/creatine-phosphocreatine (Cr) in the hypothalamus of narcolepsy patients with cataplexy. We aimed to test for metabolic changes in specific brain areas, “regions of interest,” thought to be involved in emotional processing, sleep regulation and pathophysiology of narcolepsy: hypothalamus, pontomesencephalic junction and both amygdalae. Design: We performed 1H-MRS using a 3T Philips Achieva whole body MR scanner. Single-voxel proton MR spectra were acquired and quantified with LCModel to determine metabolite concentration ratios. Setting: The participants in the study were recruited at the outpatient clinic for sleep medicine, Department of Neurology and magnetic resonance spectroscopy was performed at the MRI facility, University Hospital Zurich. Participants: 1H-MRS was performed in fourteen narcolepsy patients with cataplexy, CSF hypocretin deficiency (10/10) and HLA-DQB1*0602 positivity (14/14) and 14 age, gender and body mass index matched controls. Patients were treatment naïve or off therapy for at least 14 days before scanning. Measurements and Results: No differences were observed in the regions of interest for (total NAA)/Cr ratios. Myo-Inositol (mI)/Cr was significantly lower in the right amygdala of the patients, compared to controls (P < 0.042). Significant negative correlations only in the patients group were found between (total NAA)/Cr in hypothalamus and mI/Cr in the right amygdala (r = −0.89, P < 0.001), between mI/Cr in hypothalamus and (total NAA)/Cr in the right amygdala (r = −63, P < 0.05) and between mI/Cr in the left amygdala and total NAA)/Cr in the pontomesencephalic junction (r = −0.69, P < 0.05). Conclusion: Our findings suggest amygdala involvement and possible hypothalamo-amygdala dysfunction in narcolepsy. Citation: Poryazova R; Werth E; Khatami R; Dydak U; Meier D; Boesiger P; Bassetti CL. Evidence for metabolic hypothalamo-amygdala dysfunction in narcolepsy. SLEEP 2009;32(5):607-613. PMID:19480227

Characterization of Long-term Stability of Sodium Dithionite for Evaluation of its Potential Utility for Cr(VI) Remediation at Los Alamos National Laboratory

NASA Astrophysics Data System (ADS)

Telfeyan, K.; Migdissov, A. A.; Reimus, P. W.

2017-12-01

Sodium dithionite (Na2S2O4) has proven to be an effective remediation agent in aquifers contaminated with Cr(VI). S2O42- rapidly reduces the Fe(III) in aquifer sediments to Fe(II), which then reduces aqueous Cr(VI) to insoluble Cr(III). Previous work demonstrated that the reaction products from this treatment have no long-lasting undesirable effects. However, current literature regarding the stability of dithionite in aqueous solution and its decomposition products, which are important for developing a practical treatment approach, is sparse and inconsistent. Furthermore, S2O42- treatment effectiveness depends on site-specific geochemical and hydrological conditions, so experiments using site-specific materials are necessary to develop an optimal treatment strategy. In this study, we conducted (1) batch aqueous-phase-only experiments aimed at elucidating dithionite lifetimes and decomposition products as a function of dithionite concentration and pH, (2) batch experiments at the most practical pH for a field deployment, with use of four different representations of site aquifer sediments to evaluate dithionite reaction rates in the presence of the sediments and to determine the reduction capacity of the treated sediments, and (3) column experiments to represent a field-scale deployment of dithionite and determine the Cr(VI) reduction capacity of the reduced sediments. The aqueous-phase-only batch experiments verified the presence of S2O42- in aqueous anoxic solution beyond 100 days at alkaline pH. Each sampling interval also recorded the concentration of decomposition products, which enabled the derivation of a possible hydrolysis/decomposition reaction. In the batch experiments with sediments, dithionite reacted more rapidly than in blank solutions, but measurable concentrations remained for over a month. Cr was then added to the reactors to determine the efficacy of treatment. Depending on the sediment type and concentration of dithionite, the treated sediments were able to remove between 100 and 1000 µg Cr per gram of sediment. Column experiments then determined that the dithionite treatment of aquifer sediments could treat over 30 pore volumes of contaminated water (900 ppb Cr) prior to any breakthrough of Cr, suggesting that S2O42- should be an effective treatment agent at this site.

Computer program for determination of concentrations of trace elements in components of water systems by nondestructive activation analysis (in German)

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

Slavic, I.; Draskovic, R.; Tasovac, T.

1973-03-01

A computer program for the determination of trace elements in components of the water systems bed material, suspended material, dissolved substances, plankton, algae) by nondestructive activation analysis was developed. Results of the determination of Cr, Sb, Sc, Fe, Co, Na, and La concentrations in suspended materials from the Danube river, obtained by interpretation of data with a CDC- 3600 computer (64 k words), are presented. (auth)

In Situ Determination of Trace Elements in Fish Otoliths by Laser Ablation Double Focusing Sector Field Inductively Coupled Plasma Mass Spectrometry Using a Solution Standard Addition Calibration Method

NASA Astrophysics Data System (ADS)

Chen, Z.; Jones, C. M.

2002-05-01

Microchemistry of fish otoliths (fish ear bones) is a very useful tool for monitoring aquatic environments and fish migration. However, determination of the elemental composition in fish otolith by ICP-MS has been limited to either analysis of dissolved sample solution or measurement of limited number of trace elements by laser ablation (LA)- ICP-MS due to low sensitivity, lack of available calibration standards, and complexity of polyatomic molecular interference. In this study, a method was developed for in situ determination of trace elements in fish otoliths by laser ablation double focusing sector field ultra high sensitivity Finnigan Element 2 ICP-MS using a solution standard addition calibration method. Due to the lack of matrix-match solid calibration standards, sixteen trace elements (Na, Mg, P, Cr, Mn, Fe, Ni, Cu, Rb, Sr, Y, Cd, La, Ba, Pb and U) were determined using a solution standard calibration with Ca as an internal standard. Flexibility, easy preparation and stable signals are the advantages of using solution calibration standards. In order to resolve polyatomic molecular interferences, medium resolution (M/delta M > 4000) was used for some elements (Na, Mg, P, Cr, Mn, Fe, Ni, and Cu). Both external calibration and standard addition quantification strategies are compared and discussed. Precision, accuracy, and limits of detection are presented.

Estimation of dietary intake and target hazard quotients for metals by consumption of wines from the Canary Islands.

PubMed

Gutiérrez, Angel J; Rubio, Carmen; Moreno, Isabel M; González, A Gustavo; Gonzalez-Weller, Dailos; Bencharki, Naouel; Hardisson, Arturo; Revert, Consuelo

2017-10-01

This paper describes the impact of mineral content on wines and assesses the potential health risk from consuming these wines from Canary Islands. The metal content (B, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Zn) of red wines belonging to different regions in the Canary Islands was determined by ICP-OES. The studied wine regions were Valle de la Orotava, Tacoronte-Acentejo, Ycoden-Daute-Isora, Abona and Valle de Güimar in Tenerife Island and only one in La Gomera and La Palma Islands. According to the content found, elements could be classified in two categories: the main group including Ca, K, Mg, Na, and the ''minor'' set consisting of B, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb and Zn. Once calculated the metal intake through red wines consumption, we can conclude that Canarian drinkers are not exposed to unsafe levels of the metals studied, actually, the safety intake limits (daily) ranges between 0.9% in Zn and 2% in Cu, for normal drinkers. And also it has been demonstrated the good quality of Canarian red wines and there is no reason for health concern through the THQ calculation being the highest values determined in La Gomera wines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of marine, terrestrial and anthropogenic sources on ionic and metallic composition of rainwater at a suburban site (northwest coast of Spain)

NASA Astrophysics Data System (ADS)

Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Moscoso-Pérez, Carmen; Blanco-Heras, Gustavo; Turnes-Carou, Isabel; López-Mahía, Purificación; Muniategui-Lorenzo, Soledad; Prada-Rodríguez, Darío

2014-05-01

In the present research, the rainwater chemistry of soluble (SF) and non-soluble (NSF) fractions is studied over a one a half year period (from March 2011 to August 2012) at a suburban site (Oleiros, A Coruña, Spain). The monthly rainfall in this region during the studied period ranged from 10 to 137 mm, while the NSF ranged from 0.9 to 54 mg L-1. More rainfall occurs within October-January. Eighteen samples, which provide information pertaining to the monthly variation in chemistry, were analyzed. Trace metals (Al, As, Ba, Co, Cu, Cr, Fe, Mn, Ni, Pb, Sr, V, Zn) were enclosed in the study of both fractions of the rainwater. Major inorganic ions (Cl-, NO3-, SO42-, Na+, K+, Ca2+, Mg2+ and NH4+) were also enclosed in the study of the SF of the rainwater. After partition coefficients analysis, univariate and principal components analysis (PCA) and air mass back trajectories analysis, three sources were found for the ionic and metal composition of the SF of rainwater; terrestrial (Ca2+, non sea salt SO42-, Al and Fe), marine (Mg2+, Na+, Cl-) and anthropogenic (K+, NH4+, NO3-, Fe, Mn, Pb, Sr, V and Zn). Results also suggest ubiquitous sources for Ba, Co, Cu, Cr and Ni. One source (terrestrial) was found for NSF of rainwater.

Quantitative energy-filtered TEM imaging of interfaces

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

Bentley, J.; Kenik, E.A.; Siangchaew, K.

Quantitative elemental mapping by inner shell core-loss energy-filtered transmission electron microscopy (TEM) with a Gatan Imaging Filter (GIF) interfaced to a Philips CM30 TEM operated with a LaB{sub 6} filament at 300 kV has been applied to interfaces in a range of materials. In sensitized type 304L stainless steel aged 15 h at 600{degrees}C, grain-boundary Cr depletion occurs between Cr-rich intergranular M{sub 23}C{sub 6} particles. Images of net Cr L{sub 23} intensity show segregation profiles that agree quantitatively with focused-probe spectrum-line measurements recorded with a Gatan PEELS on a Philips EM400T/FEG (0.8 nA in 2-nm-diam probe) of the same regions.more » Rare-earth oxide additives that are used for the liquid-phase sintering of Si{sub 3}N{sub 4} generate second phases of complex composition at grain boundaries and edges. These grain boundary phases often control corrosion, crack growth and creep damage behavior. High resolution imaging has been widely and with focused probes can be compromised by beam damage, but elemental mapping by EFTEM appears not to cause appreciable beam damage.« less

Wild Plant Assessment for Heavy Metal Phytoremediation Potential along the Mafic and Ultramafic Terrain in Northern Pakistan

PubMed Central

Shah, Mohammad Tahir; Khan, Sardar; Saddique, Umar; Gul, Nida; Khan, Muhammad Usman; Malik, Riffat Naseem; Farooq, Muhammad; Naz, Alia

2013-01-01

This study investigates the wild plant species for their phytoremediation potential of macro and trace metals (MTM). For this purpose, soil and wild plant species samples were collected along mafic and ultramafic terrain in the Jijal, Dubair, and Alpuri areas of Kohistan region, northern Pakistan. These samples were analyzed for the concentrations of MTM (Na, K, Ca, Mg, Fe, Mn, Pb, Zn, Cd, Cu, Cr, Ni, and Co) using atomic absorption spectrometer (AAS-PEA-700). Soil showed significant (P < .001) contamination level, while plants had greater variability in metal uptake from the contaminated sites. Plant species such as Selaginella jacquemontii, Rumex hastatus, and Plectranthus rugosus showed multifold enrichment factor (EF) of Fe, Mn, Cr, Ni, and Co as compared to background area. Results revealed that these wild plant species have the ability to uptake and accumulate higher metals concentration. Therefore, these plant species may be used for phytoremediation of metals contaminated soil. However, higher MTM concentrations in the wild plant species could cause environmental hazards in the study area, as selected metals (Fe, Mn, Cr, Ni, Co, and Pb) have toxicological concerns. PMID:24078907

Scaling of Liquid DT Layer Capsules to an ICF Burning Plasma

NASA Astrophysics Data System (ADS)

Olson, R. E.; Peterson, R. R.; Haines, B. M.; Yi, S. A.; Bradley, P. A.; Zylstra, A. B.; Kline, J. L.; Leeper, R. J.; Batha, S. H.

2017-10-01

Recent experiments at the NIF demonstrated cryogenic liquid DT layer ICF implosions. Unlike DT ice layer implosions, DT liquid layer designs can operate with low-to-moderate convergence ratio (12

Do group 1 metal salts form deep eutectic solvents?

PubMed

Abbott, A P; D'Agostino, C; Davis, S J; Gladden, L F; Mantle, M D

2016-09-14

Mixtures of metal salts such as ZnCl 2 , AlCl 3 and CrCl 3 ·6H 2 O form eutectic mixtures with complexing agents, such as urea. The aim of this research was to see if alkali metal salts also formed eutectics in the same way. It is shown that only a limited number of sodium salts form homogeneous liquids at ambient temperatures and then only with glycerol. None of these mixtures showed eutectic behaviour but the liquids showed the physical properties similar to the group of mixtures classified as deep eutectic solvents. This study focussed on four sodium salts: NaBr, NaOAc, NaOAc·3H 2 O and Na 2 B 4 O 7 ·10H 2 O. The ionic conductivity and viscosity of these salts with glycerol were studied, and it was found that unlike previous studies of quaternary ammonium salts with glycerol, where the salt decreased the viscosity, most of the sodium salts increased the viscosity. This suggests that sodium salts have a structure making effect on glycerol. This phenomenon is probably due to the high charge density of Na + , which coordinates to the glycerol. 1 H and 23 Na NMR diffusion and relaxation methods have been used to understand the molecular dynamics in the glycerol-salt mixtures, and probe the effect of water on some of these systems. The results reveal a complex dynamic behaviour of the different species within these liquids. Generally, the translational dynamics of the 1 H species, probed by means of PFG NMR diffusion coefficients, is in line with the viscosity of these liquids. However, 1 H and 23 Na T 1 relaxation measurements suggest that the Na-containing species also play a crucial role in the structure of the liquids.

Recovery Of Chromium Metal (VI) Using Supported Liquid Membrane (SLM) Method, A study of Influence of NaCl and pH in Receiving Phase on Transport

NASA Astrophysics Data System (ADS)

Cholid Djunaidi, Muhammad; Lusiana, Retno A.; Rahayu, Maya D.

2017-06-01

Chromium metal(VI) is a valuable metal but in contrary has high toxicity, so the separation and recovery from waste are very important. One method that can be used for the separation and recovery of chromium (VI) is a Supported Liquid Membrane (SLM). SLM system contains of three main components: a supporting membrane, organic solvents and carrier compounds. The supported Membrane used in this research is Polytetrafluoroethylene (PTFE), organic solvent is kerosene, and the carrier compound used is aliquat 336. The supported liquid membrane is placed between two phases, namely, feed phase as the source of analyte (Cr(VI)) and the receiving phase as the result of separation. Feed phase is the electroplating waste which contains of chromium metal with pH variation about 4, 6 and 9. Whereas the receiving phase are the solution of HCl, NaOH, HCl-NaCl and NaOH-NaCl with pH variation about 1, 3, 5 and 7. The efficiency separation is determined by measurement of chromium in the feed and the receiving phase using AAS (Atomic Absorption Spectrophotometry). The experiment results show that transport of Chrom (VI) by Supported Liquid membrane (SLM) is influenced by pH solution in feed phase and receiving phase as well as NaCl in receiving phase. The highest chromium metal is transported from feed phase about 97,78%, whereas in receiving phase shows about 58,09%. The highest chromium metal transport happens on pH 6 in feed phase, pH 7 in receiving phase with the mixture of NaOH and NaCl using carrier compound aliquat 336.

Extraction of heavy metal ions from waste colored glass through phase separation.

PubMed

Chen, Danping; Masui, Hirotsugu; Miyoshi, Hiroshi; Akai, Tomoko; Yazawa, Tetsuo

2006-01-01

A new method utilizing phase separation phenomena for the extraction of heavy metal ions used as colorants in colored glass is proposed. Colored soda-lime-silica glass containing Co or Cr as a colorant was remelted with B2O3 to yield soda-lime-borosilicate glass. The soda-lime-borosilicate glass thus obtained was leached in 1M nitric acid at 90 degrees C to dissolve the borate phase. All cations (Na, Ca, Cr and Co) concentrated in the borate phase are successfully leached out with the dissolution of the borate phase, when the amount of the B2O3 added to the glass and heat treatment conditions are properly chosen. Porous silicate glass powders with high SiO2 purity are obtained as the result of the leaching. Porous glass can also be formed as bulk material by controlling the composition of additives during the remelting.

Effects of surface chemistry on hot corrosion life

NASA Technical Reports Server (NTRS)

Fryxell, R. E.

1984-01-01

Baseline burner rig hot corrosion with Udimet 700, Rene' 80; uncoated and with RT21, Codep, or NiCoCrAlY coatings were tested. Test conditions are: 900C, hourly thermal cycling, 0.5 ppm sodium as NaCl in the gas stream, velocity 0.3 Mach. The uncoated alloys exhibited substantial typical sulfidation in the range of 140 to 170 hours. The aluminide coatings show initial visual evidence of hot corrosion at about 400 hours, however, there is no such visual evidence for the NiCoCrAlY coatings. The turbine components show sulfidation. The extent of this distress appeared to be inversely related to the average length of mission which may, reflect greater percentage of operating time near ground level or greater percentage of operation time at takeoff conditions (higher temperatures). In some cases, however, the location of maximum distress did not exhibit the structural features of hot corrosion.

The Effect of Hydrogen Annealing on the Impurity Content of Alumina-Forming Alloys

NASA Technical Reports Server (NTRS)

Smialek, James L.

2000-01-01

Previously, the effect of hydrogen annealing on increasing the adhesion of Al2O3 scales had been related to the effective desulfurization that occurred during this process. The simultaneous reduction of other impurities has now been re-examined for up to 20 impurity elements in the case of five different alloys (NiCrAl, FeCrAl, PWA 1480, Rene'142, and Rene'N5). Hydrogen annealing produced measurable reductions in elemental concentration for B, C, Na, Mg, P, K, Sr, or Sn in varying degrees for at least one and up to three of these alloys. No single element was reduced by hydrogen annealing for all the alloys except sulfur. In many cases spalling occurred at low levels of these other impurities, while in other cases the scales were adherent at high levels of the impurities. No impurity besides sulfur was strongly correlated with adhesion.

Band gap tuning in transition metal oxides by site-specific substitution

DOEpatents

Lee, Ho Nyung; Chisholm, Jr., Matthew F; Jellison, Jr., Gerald Earle; Singh, David J; Choi, Woo Seok

2013-12-24

A transition metal oxide insulator composition having a tuned band gap includes a transition metal oxide having a perovskite or a perovskite-like crystalline structure. The transition metal oxide includes at least one first element selected form the group of Bi, Ca, Ba, Sr, Li, Na, Mg, K, Pb, and Pr; and at least one second element selected from the group of Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Hf, Ta, W, Re, Os, Ir, and Pt. At least one correlated insulator is integrated into the crystalline structure, including REMO.sub.3, wherein RE is at least one Rare Earth element, and wherein M is at least one element selected from the group of Co, V, Cr, Ni, Mn, and Fe. The composition is characterized by a band gap of less of 4.5 eV.

Quantitative Model to Predict Melts on the Ol-Opx Saturation Boundary during Mantle Melting: The Role of H2O

NASA Astrophysics Data System (ADS)

Andrews, A. L.; Grove, T. L.

2014-12-01

Two quantitative, empirical models are presented that predict mantle melt compositions in equilibrium with olivine (ol) + orthopyroxene (opx) ± spinel (sp) as a function of variable pressure and H2O content. The models consist of multiple linear regressions calibrated using new data from H2O-undersaturated primitive and depleted mantle lherzolite melting experiments as well as experimental literature data. The models investigate the roles of H2O, Pressure, 1-Mg# (1-[XMg/(XMg+XFe)]), NaK# ((Na2O+K2O)/(Na2O+K2O+CaO)), TiO2, and Cr2O3 on mantle melt compositions. Melts are represented by the pseudoternary endmembers Clinopyroxene (Cpx), Olivine (Ol), Plagioclase (Plag), and Quartz (Qz) of Tormey et al. (1987). Model A returns predictive equations for the four endmembers with identical predictor variables, whereas Model B chooses predictor variables for the four compositional endmember equations and temperature independently. We employ the use of Akaike Information Criteria (Akaike, 1974) to determine the best predictor variables from initial variables chosen through thermodynamic reasoning and by previous models. In both Models A and B, the coefficients for H2O show that increasing H2O drives the melt to more Qz normative space, as the Qz component increases by +0.012(3) per 1 wt.% H2O. The other endmember components decrease and are all three times less affected by H2O (Ol: -0.004(2); Cpx: -0.004(2); Plag: -0.004(3)). Consistent with previous models and experimental data, increasing pressure moves melt compositions to more Ol normative space at the expense of the Qz component. The models presented quantitatively determine the influence of H2O, Pressure, 1-Mg#, NaK#, TiO2, and Cr2O3 on mantle melts in equilibrium with ol+opx±sp; the equations presented can be used to predict melts of known mantle source compositions saturated in ol+opx±sp. References Tormey, Grove, & Bryan (1987), doi: 10.1007/BF00375227. Akaike (1974), doi: 10.1109/TAC.1974.1100705.

Cerebral Metabolic Alterations in Rats With Diabetic Ketoacidosis

PubMed Central

Glaser, Nicole; Yuen, Natalie; Anderson, Steven E.; Tancredi, Daniel J.; O'Donnell, Martha E.

2010-01-01

OBJECTIVE Cerebral edema is a life-threatening complication of diabetic ketoacidosis (DKA) in children. Recent data suggest that cerebral hypoperfusion and activation of cerebral ion transporters may be involved, but data describing cerebral metabolic alterations during DKA are lacking. RESEARCH DESIGN AND METHODS We evaluated 50 juvenile rats with DKA and 21 normal control rats using proton and phosphorus magnetic resonance spectroscopy (MRS). MRS measured cerebral intracellular pH and ratios of metabolites including ATP/inorganic phosphate (Pi), phosphocreatine (PCr)/Pi, N-acetyl aspartate (NAA)/creatine (Cr), and lactate/Cr before and during DKA treatment. We determined the effects of treatment with insulin and intravenous saline with or without bumetanide, an inhibitor of Na-K-2Cl cotransport, using ANCOVA with a 2 × 2 factorial study design. RESULTS Cerebral intracellular pH was decreased during DKA compared with control (mean ± SE difference −0.13 ± 0.03; P < 0.001), and lactate/Cr was elevated (0.09 ± 0.02; P < 0.001). DKA rats had lower ATP/Pi and NAA/Cr (−0.32 ± 0.10, P = 0.003, and −0.14 ± 0.04, P < 0.001, respectively) compared with controls, but PCr/Pi was not significantly decreased. During 2-h treatment with insulin/saline, ATP/Pi, PCr/Pi, and NAA/Cr declined significantly despite an increase in intracellular pH. Bumetanide treatment increased ATP/Pi and PCr/Pi and ameliorated the declines in these values with insulin/saline treatment. CONCLUSIONS These data demonstrate that cerebral metabolism is significantly compromised during DKA and that further deterioration occurs during early DKA treatment—consistent with possible effects of cerebral hypoperfusion and reperfusion injury. Treatment with bumetanide may help diminish the adverse effects of initial treatment with insulin/saline. PMID:20028943

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.

Removal of anionic dyes (Reactive Black 5 and Congo Red) from aqueous solutions using Banana Peel Powder as an adsorbent.

PubMed

Munagapati, Venkata Subbaiah; Yarramuthi, Vijaya; Kim, Yeji; Lee, Kwon Min; Kim, Dong-Su

2018-02-01

The adsorption characteristics of Reactive Black 5 (RB5) and Cong Red (CR) onto Banana Peel Powder (BPP) from aqueous solution were investigated as a function of pH, contact time, initial dye concentration and temperature. The BPP was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis. FTIR results revealed that hydroxyl (-OH), amine (-NH) and carboxyl (-C˭O) functional groups present on the surface of BPP. The SEM results show that BPP has an irregular and porous surface morphology which is adequate for dye adsorption. The equilibrium data were analyzed using Langmuir and Freundlich isotherm models. Experimental results were best represented by the Langmuir isotherm model. The adjustments of models were confirmed by the Chi-square (χ 2 ) test and the correlation coefficients (R 2 ). The maximum monolayer adsorption capacities of RB5 and CR on BPP calculated from Langmuir isotherm model were 49.2 and 164.6mg/g at pH 3.0 and 298K. Experimental data were also tested in terms of adsorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption processes of both RB5 and CR followed well pseudo-second-order kinetic models. The calculated thermodynamic parameters ΔG°, ΔH° and ΔS° showed that the adsorption of RB5 and CR onto BPP was feasible, spontaneous and endothermic in the temperature range 298-318K. The RB5 and CR were desorbed from BPP using 0.1M NaOH. The recovery for both anionic dyes was found to be higher than 90%. Based on these it can be concluded that BPP can be used as an effective, low cost, and eco-friendly adsorbent for CR removal than RB5 from aqueous solution. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of the process of recycling and renal parenchymal injury after eswl with metabolites excreted in the urine.

PubMed

Ceylan, Cavit; Dogan, Serkan; Saydam, Gulsevim; Kocak, Mehmet Zait; Doluoglu, Omer Gokhan

2013-01-01

To show renal parenchymal injury depending on extracorporeal shock wave lithotripsy (ESWL). The patients with one renal stone and in whom ESWL is planned among the patients in whom renal stone was determined. Their 24-h urine samples were collected just before and after the ESWL treatment. Cit (citrate), UrA (uric acid), RBP (retinol-binding protein), NAG (N-acetyl-β-Đ-glucosaminidase), Cr (creatinine), Na (sodium), K (potassium), P (phosphor), Ca (calcium), and Cl (chlorine) metabolites excreted in urine were evaluated after urine samples were taken on the study day. Changes in the metabolites excreted; the number, frequency, and duration of ESWL shock wave; the energy; and the body mass index were recorded. The results for p < 0.05 will be accepted as statistically significant. Two sessions of ESWL were applied to a total of 20 patients. When metabolites excreted in the urine before (B1E) and after (A1E) the first session of ESWL, and before (B2E) and after (A2E) the second session of ESWL, were evaluated, no statistically significant result for Ca and Cl excretion was noted. For NAG and Cr, a significant difference was observed in terms of metabolite excretion between B1E and B2E. For other metabolites, we saw that there is no difference between B1E and B2E. While a significant metabolite change was observed for RBP, NAG, Cr, and Na as long as A1E and A2E ESWL session number increases, other metabolites were not significant. Shock waves induce significant damage to the renal and adjacent tissues as indicated by a significant increase in cell-escaped enzymes and electrolytes and the extent of damage depends on the energy and the number of shock wave exposure.

Geochemistry and mineralogy of sediments from the Ventersdorp and Transvaal Supergroups, South Africa: Cratonic evolution during the early Proterozoic

NASA Astrophysics Data System (ADS)

Wronkiewicz, David J.; Condie, Kent C.

1990-02-01

Approximately 100 pelite and 12 quartzite samples from the Ventersdorp (~2.7 Ga) and Transvaal Supergroups (~2.6-2.1 Ga) have been analyzed to monitor the early Proterozoic evolution of the Kaapvaal Craton, southern Africa. From oldest to youngest, pelites were sampled from the Ventersdorp-Bothaville (BOT), Transvaal-Selati (SEL), Black Reef (BR), Timeball Hill (TH), Strubenkop (STR), and Silverton (SIL) Formations. Paleocurrent measurements in Transvaal quartzites indicate sources lying predominantly to the north and east. Relative to the BOT-SEL-BR, pelites from the TH-STR-SIL are enriched in heavy-REE, LILE, Zr, Hf, Nb, and Ta, depleted in K 2O, MgO, Ni, and Cr, and have lower Cr/Zr, Sc/Th, K 2O/Na 2O, and K/ Rb ratios. Compared to SEL-BR, BOT-TH-STR-SIL pelites have higher light-REE contents and La/Yb ratios, and lower Eu/Eu∗ ratios (0.61-0.66). Relative to NASC (North American Shale Composite), THSTR-SIL pelites are enriched in light-REE, Th, U, Ta, Nb, Sc, Cs, have higher La/Yb ratios, and are depleted in K 2O and MgO. BOT-SEL-BR pelites are enriched in K 2O, MgO, Cr, and Ni, have higher K 2O/Na 2O, Sc/Th, and Eu/Eu∗ ratios, and are depleted in Th, U, heavy-REE, and High Field Strength Elements (HFSE) relative to NASC. Compositions of TH-STR-SIL pelites suggest a provenance similar to average Phanerozoic uppercontinental crust. This source is more evolved than that of BOT-SEL-BR pelites, indicating a transformation from primitive (mafic-rich) to evolved (felsic-rich) upper-crust at 2.2 Ga. This transition follows earlier primitive to evolved trends in Moodies-Pongola (3.3-3.0 Ga) and Witwatersrand (~2.8 Ga) successions. These data suggest that several cycles of changing upper-continental crust occurred in the Kaapvaal craton between 3.3-2.1 Ga.

Timescales between mantle metasomatism and kimberlite ascent indicated by diffusion profiles in garnet crystals from peridotite xenoliths

NASA Astrophysics Data System (ADS)

Jollands, Michael C.; Hanger, Brendan J.; Yaxley, Gregory M.; Hermann, Jörg; Kilburn, Matthew R.

2018-01-01

Rare garnet crystals from a peridotite xenolith from the Wesselton kimberlite, South Africa, have distinct zones related to two separate episodes of mantle metasomatism. The garnet cores were firstly depleted through melt extraction, then equilibrated during metasomatism by a potentially diamond-forming carbonate-bearing or proto-kimberlitic fluid at 1100-1300 °C and 4.5-5.5 GPa. The garnet rim chemistry, in contrast, is consistent with later overgrowth in equilibrium with a kimberlite at around 1025 ± 25 °C and 4.2 ± 0.5 GPa. This suggests that the rock was physically moved upwards by up to tens of kilometres between the two metasomatic episodes. Preserved high Ca, Al and Cr contents in orthopyroxenes suggest this uplift was tectonic, rather than magmatic. Diffusion profiles were measured over the transitions between garnet cores and rims using electron microprobe (Mg, Ca, Fe for modelling, plus Cr, Mn, Ti, Na, Al) and nano Secondary Ion Mass Spectrometry (NanoSIMS; 89Y, along with 23Na, Ca, Cr, Fe, Mn and Ti) analyses. The short profile lengths (generally <10 μm) and low Y concentrations (0.2-60 ppm) make the NanoSIMS approach preferable. Diffusion profiles at the interface between the zones yield constraints on the timescale between the second metasomatic event and eruption of the kimberlite magma that brought the xenolith to the surface. The time taken to form the diffusion profiles is on the order of 25 days to 400 yr, primarily based on modelling of Y diffusion along with Ca, Fe and Mg (multicomponent diffusion) profiles. These timescales are too long to be produced by the interaction of the mantle xenolith with the host kimberlite magma during a single-stage ascent to the crust (hours to days). The samples offer a rare opportunity to study metasomatic processes associated with failed eruption attempts in the cratonic lithosphere.

Determination of selected trace elements in foodstuffs and biological materials by destructive neutron activation analysis.

PubMed

Bayat, I; Etehadiyan, M; Ansar, M

1995-01-01

Concentration of trace elements in Nescafé, Fariman sugar, and Sadaf turmeric and mercury content in cancerous blood were determined by radiochemical, neutron activation analysis. By this separation method levels of 110mAg, 198Au, 203Hg, 76Se, 51Cr, 24Na, 42K, 99Mo, 122Sb, 82Br, 59Fe, 60Co were measured without interference in the gamma spectroscopy. A nondestructive method has also been used for the analysis of sodium, potassium, and bromine.

Corrosion of austenitic steels and their components in vanadium-containing chloride melts

NASA Astrophysics Data System (ADS)

Abramov, A. V.; Polovov, I. B.; Rebrin, O. I.; Lisienko, D. G.

2014-08-01

The corrosion of austenitic 12Kh18N10T, 10Kh17N13M2T, and 03Kh17N14M3 steels and their components (Cr, Fe, Ni, Mo) in NaCl-KCl-VCl2 melts with 5 wt % V at 750°C is studied. The rates and mechanisms of corrosion of the materials under these conditions are determined. The processes that occur during contact of the metals and steels with vanadium-containing chloride electrolytes are investigated.

Dynamic nuclear polarization of (1)H, (13)C, and (59)Co in a tris(ethylenediamine)cobalt(III) crystalline lattice doped with Cr(III).

PubMed

Corzilius, Björn; Michaelis, Vladimir K; Penzel, Susanne A; Ravera, Enrico; Smith, Albert A; Luchinat, Claudio; Griffin, Robert G

2014-08-20

The study of inorganic crystalline materials by solid-state NMR spectroscopy is often complicated by the low sensitivity of heavy nuclei. However, these materials often contain or can be prepared with paramagnetic dopants without significantly affecting the structure of the crystalline host. Dynamic nuclear polarization (DNP) is generally capable of enhancing NMR signals by transferring the magnetization of unpaired electrons to the nuclei. Therefore, the NMR sensitivity in these paramagnetically doped crystals might be increased by DNP. In this paper we demonstrate the possibility of efficient DNP transfer in polycrystalline samples of [Co(en)3Cl3]2·NaCl·6H2O (en = ethylenediamine, C2H8N2) doped with Cr(III) in varying concentrations between 0.1 and 3 mol %. We demonstrate that (1)H, (13)C, and (59)Co can be polarized by irradiation of Cr(III) with 140 GHz microwaves at a magnetic field of 5 T. We further explain our findings on the basis of electron paramagnetic resonance spectroscopy of the Cr(III) site and analysis of its temperature-dependent zero-field splitting, as well as the dependence of the DNP enhancement factor on the external magnetic field and microwave power. This first demonstration of DNP transfer from one paramagnetic metal ion to its diamagnetic host metal ion will pave the way for future applications of DNP in paramagnetically doped materials or metalloproteins.

Dynamic Nuclear Polarization of 1H, 13C, and 59Co in a Tris(ethylenediamine)cobalt(III) Crystalline Lattice Doped with Cr(III)

PubMed Central

2015-01-01

The study of inorganic crystalline materials by solid-state NMR spectroscopy is often complicated by the low sensitivity of heavy nuclei. However, these materials often contain or can be prepared with paramagnetic dopants without significantly affecting the structure of the crystalline host. Dynamic nuclear polarization (DNP) is generally capable of enhancing NMR signals by transferring the magnetization of unpaired electrons to the nuclei. Therefore, the NMR sensitivity in these paramagnetically doped crystals might be increased by DNP. In this paper we demonstrate the possibility of efficient DNP transfer in polycrystalline samples of [Co(en)3Cl3]2·NaCl·6H2O (en = ethylenediamine, C2H8N2) doped with Cr(III) in varying concentrations between 0.1 and 3 mol %. We demonstrate that 1H, 13C, and 59Co can be polarized by irradiation of Cr(III) with 140 GHz microwaves at a magnetic field of 5 T. We further explain our findings on the basis of electron paramagnetic resonance spectroscopy of the Cr(III) site and analysis of its temperature-dependent zero-field splitting, as well as the dependence of the DNP enhancement factor on the external magnetic field and microwave power. This first demonstration of DNP transfer from one paramagnetic metal ion to its diamagnetic host metal ion will pave the way for future applications of DNP in paramagnetically doped materials or metalloproteins. PMID:25069794

Thermometric studies on the Fe(III)-EDTA chelate.

PubMed

Dot, K

1978-02-01

A DeltaH of -11.5 +/- 0.5 kJ/mole has been determined for the formation of the Fe(III)-EDTA chelate at 25.0 degrees and mu = 0.1(= [HClO(4)] + [NaClO(4)]) by a direct thermometric titration procedure. The entropy change, DeltaS, has been calculated to be 440 J.mole(-1) .deg(-1) by combining the result of the heat measurements with the free energy change obtained from the stability constant previously determined. A relationship between the DeltaS values and the standard partial molal entropies of the tervalent metal ions is discussed. In addition, conditions for the thermometric titration of Fe(III) with NA(4)EDTA at room temperature have been investigated. Iron(III) can be determined in the presence of fairly large amounts of phosphate, Cr(III), Mn(II) and Al(III).

Anode materials for lithium ion batteries

DOEpatents

Abouimrane, Ali; Amine, Khalil

2015-06-09

A composite material has general Formula (1-x)J-(x)Q wherein: J is a metal carbon alloy of formula Sn.sub.zSi.sub.z'Met.sub.wMet'.sub.w'C.sub.t; Q is a metal oxide of formula A.sub..gamma.M.sub..alpha.M'.sub..alpha.'O.sub..beta.; A is Li, Na, or K; M, M', Met, and Met' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; 0

Proton Spectroscopy in a Cross-Section of HIV-Positive Asymptomatic Patients Receiving Immediate Compared with Deferred Zidovudine (Concorde Study).

PubMed

Hall-Craggs, M A; Williams, I G; Wilkinson, I D; Paley, M; Chinn, R J; Chong, W K; Kendall, B E; Harrison, M J; Baldeweg, T; Pugh, K; Riccio, M; Catalan, J; Weller, I V

1997-01-01

The purpose of this study was to examine by proton spectroscopy for any difference in cerebral metabolites in patients taking part in the Concorde study (comparing the efficacy of immediate versus deferred treatment with zidovudine on asymptomatic HIV infected individuals). Forty seven HIV positive male patients [29 immediate, 18 deferred zidovudine] were examined in the last 9 months of the therapeutic trial. Magnetic resonance imaging and proton spectroscopy were performed at 1.5 Tesla using a single voxel placed in the parieto-occipital white matter. No significant difference was found in metabolite ratios comparing immediate versus deferred zidovudine (NA/NA+Cho+Cr 0.52 vs. 0.52). High quality spectra were acquired in relatively large numbers of patients and logistically spectroscopy may be applied to clinical therapeutic studies.

Potential influence of tubular dysfunction on the difference between estimated and measured glomerular filtration rate after kidney transplantation.

PubMed

Lezaic, V; Mirkovic, D; Ristic, S; Radivojevic, D; Dajak, M; Naumovic, R; Marinkovic, J; Djukanovic, L J

2013-05-01

Because no consensus exists regarding the most accurate calculation to estimate glomerular filtration rate (GFR) based on serum creatinine concentrations (sCr) after kidney transplantation, this study sought to assess the potential role of tubular dysfunction on GFR estimates using various equations as well as the effect of pharmacologic blockades on tubular secretion of creatinine on creatinine clearance (ClCr). Iohexol GFR (mGFR) was performed in 17 stable kidney transplant recipients(R) at >24 months post-transplantation. Their mean age was 48.3 ± 11.3 years. All R were treated with a calcineurin inhibitor (CNI). At the time of study we measured sCr, 24 hour-ClCr, cystatin C, 24-hour proteinuria, microalbuminuria, FE Na, alfa1-microglobulinuria (alfa1-MG), and CNI concentrations. To block tubular secretion of Cr, recipients were prescribed cimetidine (2400 mg) 2 days before the sCr measurement. Additionally, to exclude dietary influences on sCr, R did not eat meat for 2 days before testing. GFR was estimated using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockroft-Gault (C&G), and Cystatin C (Cyst C) GFR equations. Mean kidney graft function over the previous 6 months was used as the control. Pearson correlation was determined between the differences between mGFR and estimatedGFR: Iohexol minus MDRD, EPI, Cyst C or C&G GFR for paired estimates. The diagnostic accuracy of the eGFRs to detect an mGFR of 60 mL/min/1.73 m(2) was examined by receiver operating characteristic curves. Mean mGFR was 75.2 ± 35.8 mL/min/1.73 m(2). The sCr increased but the 24-hour ClCr, MDRD, EPI, and C&G decreased after vs before cimetidine. The difference was significant for sCr (F = 12.933; P = .002) and MDRD GFR (F = 15.750; P = .001). mGFR was not significantly higher than all pair values of eGFRs, and not significantly lower than 24-hour ClCr before and after cimetidine. However, in comparison to all eGFRs, ClCr after cimetidine most approached mGFR. A significant positive correlation was observed between alfa1-MG and the difference between mGFR and MDRD (before, r = .543 [P = .045]; after cimetidine, 0.568 [P = .034]), EPI (before, r = 0.516 [P = .050]; after cimetidine, r = 0.562 [P = .036]), and ClCr (r = 0.633; P = .016), C&G (P = .581; P = .029) before cimetidine. Accuracy of eGFRs to detect mGFR of 60 mL/min/1.73 m(2) showed EPI GFR before cimetidine to show diagnostic accuracy for patients with GFR >60 mL/min/1.73 m(2) with a sensitivity of 81.8% and a specificity of 71.4%. Because mGFR is unavailable in many transplant centers, determination of ClCr after cimetidine may help to achieve a more accurate diagnosis of CKD among transplant patients. Copyright © 2013 Elsevier Inc. All rights reserved.

Embryo-larval toxicity tests with the African catfish (Clarias gariepinus): comparative sensitivity of endpoints.

PubMed

Nguyen, L T H; Janssen, C R

2002-02-01

Embryo-larval toxicity tests with the African catfish (Clarias gariepinus) were performed to assess the comparative sensitivity of different endpoints. Measured test responses included embryo and larval survival, hatching, morphological development, and larval growth. Chromium, cadmium, copper, sodium pentachlorphenol (NaPCP), and malathion were used as model toxicants. Hatching was not affected by any of the chemicals tested, and embryo survival was only affected by chromium at > or = 36 mg/L. The growth of larvae was significantly reduced at > or = 11 mg/L Cr, > or = 0.63 mg/L Cu, > or = 0.03 mg/L NaPCP, and > or = 1.25 mg/L malathion. Morphological development of C. gariepinus was affected by all of the toxicants tested. Different types of morphological aberrations were observed, i.e., reduction of pigmentation in fish exposed to cadmium and copper, yolk sac edema in fish exposed to NaPCP and malathion, and deformation of the notochord in fish exposed to chromium and malathion. The sensitivity of the endpoints measured can be summarized as follows: growth > abnormality > larval survival > embryo survival > hatching.

Removal of anionic and cationic dyes with bioadsorbent oxidized chitosans.

PubMed

León, Orietta; Muñoz-Bonilla, Alexandra; Soto, Diana; Pérez, Daniela; Rangel, Medarda; Colina, Marinela; Fernández-García, Marta

2018-08-15

Different oxidized chitosans were prepared following various approaches, by thermo-acid oxidation or by using KMnO 4 /NaHSO 3 , (NH 4 ) 2 S 2 O 8 /NaHSO 3 and K 2 Cr 2 O 7 /NaHSO 3 redox pairs added sequentially or simultaneously. All these reactions pursue the formation of carboxylic groups which enhance their capability to remove model cationic and anionic dyes such as methylene blue and methyl orange, respectively. The resulting oxidized chitosans were structurally and thermally characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy and thermogravimetry. The swelling capacity of these hydrogels was also determined as well as the remediation ability of dyes in different conditions. The results showed that the adsorption of methylene blue followed a pseudo second-order kinetics model, while the adsorption behavior was in agreement with the Langmuir isotherm model. Remarkably, the oxidized chitosans showed removal ability for both dyes cationic and anionic, which of great importance for application of these materials as versatile bioadsorbents. Copyright © 2018 Elsevier Ltd. All rights reserved.

On the entropy of glaucophane Na2Mg3Al2Si8O22(OH)2

USGS Publications Warehouse

Robie, R.A.; Hemingway, B.S.; Gillet, P.; Reynard, B.

1991-01-01

The heat capacity of glaucophane from the Sesia-Lanza region of Italy having the approximate composition (Na1.93Ca0.05Fe0.02) (Mg2.60Fe0.41) (Al1.83Fe0.15Cr0.01) (Si7.92Al0.08)O22(OH)2 was measured by adiabatic calorimetry between 4.6 and 359.4 K. After correcting the Cp0data to values for ideal glaucophane, Na2Mg3Al2Si8O22(OH)2 the third-law entropy S2980-S00was calculated to be 541.2??3.0 J??mol-1??K-1. Our value for S2980-S00is 12.0 J??mol-1??K-1 (2.2%) smaller than the value of Likhoydov et al. (1982), 553.2??3.0, is within 6.2 J??mol-1??K-1 of the value estimated by Holland (1988), and agrees remarkably well with the value calculated by Gillet et al. (1989) from spectroscopic data, 539 J??mol-1??K-1. ?? 1991 Springer-Verlag.

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

Developing high strength and ductility in biomedical Co-Cr cast alloys by simultaneous doping with nitrogen and carbon.

PubMed

Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

2016-02-01

There is a strong demand for biomedical Co-Cr-based cast alloys with enhanced mechanical properties for use in dental applications. We present a design strategy for development of Co-Cr-based cast alloys with very high strength, comparable to that of wrought Co-Cr alloys, without loss of ductility. The strategy consists of simultaneous doping of nitrogen and carbon, accompanied by increasing of the Cr content to increase the nitrogen solubility. The strategy was verified by preparing Co-33Cr-9W-0.35N-(0.01-0.31)C (mass%) alloys. We determined the carbon concentration dependence of the microstructures and their mechanical properties. Metal ion release of the alloys in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid was also evaluated to ensure their corrosion resistance. As a result of the nitrogen doping, the formation of a brittle σ-phase, a chromium-rich intermetallic compound, was significantly suppressed. Adding carbon to the alloys resulted in finer-grained microstructures and carbide precipitation; accordingly, the strength increased with increasing carbon concentration. The tensile ductility, on the other hand, increased with increasing carbon concentration only up to a point, reaching a maximum at a carbon concentration of ∼0.1mass% and decreasing with further carbon doping. However, the alloy with 0.31mass% of carbon exhibited 14% elongation and also possessed very high strength (725MPa in 0.2% proof stress). The addition of carbon did not significantly degrade the corrosion resistance. The results show that our strategy realizes a novel high-strength Co-Cr-based cast alloy that can be produced for advanced dental applications using a conventional casting procedure. The present study suggested a novel alloy design concept for realizing high-strength Co-Cr-based cast alloys. The proposed strategy is beneficial from the practical point of view because it uses conventional casting approach-a simpler, more cost-effective, industrially friendly manufacturing process than other manufacturing processes such as thermomechanical processing or powder metallurgy. The developed alloys showed the excellent strength-ductility balance and significantly high strength comparable to that of wrought Co-Cr-Mo alloys, while maintaining acceptable ductility and good corrosion resistance. We described the relationship between microstructures and mechanical and corrosion prosperities of the developed alloys; this provides the fundamental aspect of the proposed strategy and will be helpful for further investigations or industrial realization of the proposed strategy. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Comparison of classic and microwave-assisted synthesis of benzo-thio crown ethers, and investigation of their ion pair extractions

NASA Astrophysics Data System (ADS)

Calisir, Umit; Çiçek, Baki

2017-11-01

Macrocyclic benzo-thio crown ethers and benzo-oxo crown ethers were prepared using an esterification-ring closing method. These compounds were synthesised using 2,2‧-dithiodibenzoyl chloride, and various glycols and dithiols, in the presence of pyridine base under a nitrogen atmosphere in chloroform. All reactions were performed under reflux condition with conventional heating and microwave (MW) irradiation. The synthesised macrocycles were characterised by FT-IR, 1H NMR, 13C NMR, LC-MS, and elemental analysis methods. Extraction studies have been performed on these original macrocycles using liquid-liquid ion-pair extraction with Li+, Na+, K+, Ni2+, Ca2+, Mg2+, Zn2+, Fe2+,Fe3+, Co3+, Pb2+, Cr3+, Ag+, and Cd2+.The KD, ext.%, ΔG and log KExt values were also calculated. While (U1-U7) ligands exhibits selectivity for Zn2+, Ag+, Ca2+, Pb2+, Fe3+, Cr3+, Co2+, Mg2+, Cd2+, and Ni2+ metal salts, they showed no selectivity for Li+, K+ and Na+ metal salts. Furthermore, Fe3+is the most selective cation for all ligands for competitive extraction. We also observed that microwave heating can have certain benefits over conventional ovens: reaction rate acceleration, milder reaction conditions, higher chemical yield, and lower energy usage. These ligands could be used as metal sensors, enzyme inhibitors, antimicrobial/antifungal agents, and in biological applications.

APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

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

Hasselquist, Sten; Holtzman, Jon; Shetrone, Matthew

The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars withmore » [Fe/H] ≳ −0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.« less

APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

NASA Astrophysics Data System (ADS)

Hasselquist, Sten; Shetrone, Matthew; Smith, Verne; Holtzman, Jon; McWilliam, Andrew; Fernández-Trincado, J. G.; Beers, Timothy C.; Majewski, Steven R.; Nidever, David L.; Tang, Baitian; Tissera, Patricia B.; Fernández Alvar, Emma; Allende Prieto, Carlos; Almeida, Andres; Anguiano, Borja; Battaglia, Giuseppina; Carigi, Leticia; Delgado Inglada, Gloria; Frinchaboy, Peter; García-Hernández, D. A.; Geisler, Doug; Minniti, Dante; Placco, Vinicius M.; Schultheis, Mathias; Sobeck, Jennifer; Villanova, Sandro

2017-08-01

The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] ≳ -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.

Concentrates and mantle xenocrysts from the Lao river Guinea and reconstructions of the mantle structure

NASA Astrophysics Data System (ADS)

Afanasiev, Valentin; Ashchepkov, Igor; Nikolenko, Eeugeny

2015-04-01

The discovery of the kimberlite dykes in Quinea in the basin of the Lao river means finding of the new diamondiferous kimberlite field in the West Africa. It is locating 100 km SW from Bubudu and contains large dykes and placers in Lao river. The kimberlite concentrate and diamondiferous placers are containing pyropes, chromites, Ilmenites and Cr diosides and low Cr- pyroxenes. Two river placers in Lao and Bobeko and newly discovered dyke slightly differ in compositions of minerals. mainly in representatives of the minerals though their compositional trends are in general similar. The concentrates from and Druzhba pipe (Bunudu) contains mainly ilmenite and more are pyropes. Garnets from all localities are close and belong mainly to the lherzolite field to 10 wt%Cr2O3. But the dyke contains essential amount of harzburgitic garnets starting from 2 %wt Cr2O3 and they became prevailing from 6 wt %Cr2O3. There are also megacrystic low - Cr pyropes in dyke concentrate. Dyke is rich in peridotites and coarse grained garnet pyroxenite xenoliths which are ranging from the low Cr -to Cr -diopside type Chromites from Dyke are Ti - low but are often Al rich. While chromites from Bobeko and especially Lao placers define the Cr- rich trend from 60 to 40 wt%Cr2O3 and demonstrate the deviation to ulvospinel trends with increasing of Al2O3 . Cr - Diopsides clinopyroxenites trace the Fe- Ti-Na-Al enrichment trend. Ilmenites from three localities - define close trends splitting to the two intervals 60-40 wt% TiO2 and 33-27 TiO2 which are enriched in Cr2O3 to 5wt% reflecting the crystallization of megacrystalline association at the lithosphere base and Ilm metasomatic vein stockwark near the Moho in pre-eruption feeding system. The Dyke ilmenites are Mg rich and mainly are captured from the deep part of the mantle section. Babeko and Druzhba localities are similar variations of ilmenite trends. Some ilmenites from Lao and Druzhba are Mn - rich and are less in Cr possibly reflecting the interaction protokimberlite magma with subducted material. The calculated PTXFO2 diagrams with monominreral methods (Ashchepkov et al ., 2010 -2014) the layered structure and presence of thick pyroxenite enriched lens in the middle part of mantle section which also contain harzburgite associations. He interval 4.5-5.5 GPa contains the Crromite bearing peridotites together with Ga- harburghites. Cr- low pyroxenites probablly are associated with the ilmenites while some of them are more Fe rich and reflects the de -eclogitization. The typical deformed peridotite association were not detected but heating for the garnets is found along the magma feeder traced by ilmenites. The TRE geochemistry show that most of Cr clinopyroxenes are typical for Ga- bearing peridotites with concave upward REE patterns. They are also are rich in Nb - Ba- U and extremely depleted in Zr suggesting probably the preceding depletion with the H2O rich melts . Zircon is abundant in concentrates what corresponds to large scale H2O bearing metasomatism. Garnets demonstrates semi round HREE - high patterns with MREE humper typical for pyroxenites and small LREE- enrichment. RFBR grants 05-05-64718, 03-05-64146; 11 -05-00060a 11-05-91060-PICSа

Prospective study of serial 18F-FDG PET and 18F-fluoride (18F-NaF) PET to predict time to skeletal related events, time-to-progression, and survival in patients with bone-dominant metastatic breast cancer.

PubMed

Peterson, Lanell M; O'Sullivan, Janet; Wu, Qian Vicky; Novakova-Jiresova, Alena; Jenkins, Isaac; Lee, Jean H; Shields, Andrew; Montgomery, Susan; Linden, Hannah M; Gralow, Julie R; Gadi, Vijayakrishna K; Muzi, Mark; Kinahan, Paul E; Mankoff, David A; Specht, Jennifer M

2018-05-10

Assessing therapy response of breast cancer bone metastases is challenging. In retrospective studies, serial 18 F-FDG PET was predictive of time to skeletal related events (tSRE) and time-to-progression (TTP). 18 F-NaF PET improves bone metastasis detection compared to bone scans. We prospectively tested 18 F-FDG PET and 18 F-NaF PET to predict tSRE, TTP, and overall survival (OS) in patients with bone-dominant metastatic breast cancer (BD MBC). Methods: Patients with BD MBC were imaged with 18 F-FDG PET and 18 F-NaF PET prior to starting new therapy (scan1) and again at a range of times centered around approximately 4 months later (scan2). SUV max and SULpeak were recorded for a single index lesion and up to 5 most dominant lesions for each scan. tSRE, TTP, and OS were assessed exclusive of the PET images. Univariate Cox regression was performed to test the association between clinical endpoints and 18 F-FDG PET and 18 F-NaF PET measures. mPERCIST (Modified PET Response Criteria in Solid Tumors) criteria were also applied. Survival curves for mPERCIST compared response categories of Complete Response+Partial Response+Stable Disease versus Progressive Disease (CR+PR+SD vs PD) for tSRE, TTP, and OS. Results: Twenty-eight patients were evaluated. Higher FDG SULpeak at scan2 predicted shorter time to tSRE ( P = <0.001) and TTP ( P = 0.044). Higher FDG SUV max at scan2 predicted a shorter time to tSRE ( P = <0.001). A multivariable model using FDG SUV max of the index lesion at scan1 plus the difference in SUV max of up to 5 lesions between scans was predictive for tSRE and TTP. Among 24 patients evaluable by 18 F-FDG PET mPERCIST, tSRE and TTP were longer in responders (CR, PR, or stable) compared to non-responders (PD) ( P = 0.007, 0.028 respectively), with a trend toward improved survival ( P = 0.1). An increase in the uptake between scans of up to 5 lesions by 18 F-NaF PET was associated with longer OS ( P = 0.027). Conclusion: Changes in 18 F-FDG PET parameters during therapy are predictive of tSRE and TTP, but not OS. mPERCIST evaluation in bone lesions may be useful in assessing response to therapy and is worthy of evaluation in multicenter, prospective trials. Serial 18 F-NaF PET was associated with OS, but was not useful for predicting TTP or tSRE in BD MBC. Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Experiences in the Family Health Strategy: demands and vulnerabilities in the territory.

PubMed

Pinto, Antonio Germane Alves; Jorge, Maria Salete Bessa; Marinho, Mirna Neyara Alexandre de Sá Barreto; Vidal, Emery Ciana Figueirêdo; Aquino, Priscila de Souza; Vidal, Eglídia Carla Figueirêdo

2017-01-01

To understand the daily demands of Family Health Strategy in clinical practice of the team and social vulnerabilities of community territory. Research with qualitative approach, in a critical-reflexive perspective, held with two teams of the Family Health Strategy, in the city of Fortaleza, State of Ceará, Brazil. The participants were 22 users and 19 health professionals from the basic health network. Data from the interviews and observation were analyzed under the assumptions of critical hermeneutics. We highlight the unveiling of sufferings and daily clashes, the influence of social determinants on health and psychosocial demands, limits and possibilities of everyday clinical practice. The clinic attention must recognize the perceptions and living conditions by listening and promoting health in the community. Compreender as demandas cotidianas da Estratégia Saúde da Família na prática clínica da equipe e as vulnerabilidades sociais do território comunitário. Pesquisa com abordagem qualitativa, numa perspectiva crítico-reflexiva, realizada com duas equipes da Estratégia Saúde da Família, no município de Fortaleza, Estado do Ceará, Brasil. Os participantes foram 22 usuários e 19 profissionais de saúde da rede básica de saúde. Os dados das entrevistas e observação foram analisados sob os pressupostos da hermenêutica crítica. Evidenciam-se o desvelamento de sofrimentos e enfrentamentos cotidianos, a influência dos determinantes sociais na saúde e as demandas psicossociais, limites e possibilidades da prática clínica cotidiana. Considera-se que a atenção clínica deve reconhecer as percepções e condições de vida pela escuta e ações de promoção de saúde na comunidade.

Mass and number size distributions of particulate matter components: comparison of an industrial site and an urban background site.

PubMed

Taiwo, Adewale M; Beddows, David C S; Shi, Zongbo; Harrison, Roy M

2014-03-15

Size-resolved composition of particulate matter (PM) sampled in the industrial town of Port Talbot (PT), UK was determined in comparison to a typical urban background site in Birmingham (EROS). A Micro-Orifice Uniform Deposit Impactor (MOUDI) sampler was deployed for two separate sampling campaigns with the addition of a Grimm optical spectrometer at the PT site. MOUDI samples were analysed for water-soluble anions (Cl(-), NO₃(-) and SO₄(2-)) and cations (Na(+), NH4(+), K(+), Mg(2+) and Ca(2+)) and trace metals (Al, V, Cr, Mn, Fe, Cu, Zn, Sb, Ba and Pb). The PM mass distribution showed a predominance of fine particle (PM₂.₅) mass at EROS whereas the PT samples were dominated by the coarse fraction (PM₂.₅₋₁₀). SO₄(2-), Cl(-), NH4(+), Na(+), NO₃(-), and Ca(2+) were the predominant ionic species at both sites while Al and Fe were the metals with highest concentrations at both sites. Mean concentrations of Cl(-), Na(+), K(+), Ca(2+), Mg(2+), Cr, Mn, Fe and Zn were higher at PT than EROS due to industrial and marine influences. The contribution of regional pollution by sulphate, ammonium and nitrate was greater at EROS relative to PT. The traffic signatures of Cu, Sb, Ba and Pb were particularly prominent at EROS. Overall, PM at EROS was dominated by secondary aerosol and traffic-related particles while PT was heavily influenced by industrial activities and marine aerosol. Profound influences of wind direction are seen in the 72-hour data, especially in relation to the PT local sources. Measurements of particle number in 14 separate size bins plotted as a function of wind direction and speed are highly indicative of contributing sources, with local traffic dominant below 0.5 μm, steelworks emissions from 0.5 to 15 μm, and marine aerosol above 15 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

On the nature of absorption features toward nearby stars

NASA Astrophysics Data System (ADS)

Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

2016-06-01

Context. Diffuse interstellar absorption bands (DIBs) of largely unknown chemical origin are regularly observed primarily in distant early-type stars. More recently, detections in nearby late-type stars have also been claimed. These stars' spectra are dominated by stellar absorption lines. Specifically, strong interstellar atomic and DIB absorption has been reported in τ Boo. Aims: We test these claims by studying the strength of interstellar absorption in high-resolution TIGRE spectra of the nearby stars τ Boo, HD 33608, and α CrB. Methods: We focus our analysis on a strong DIB located at 5780.61 Å and on the absorption of interstellar Na. First, we carry out a differential analysis by comparing the spectra of the highly similar F-stars, τ Boo and HD 33608, whose light, however, samples different lines of sight. To obtain absolute values for the DIB absorption, we compare the observed spectra of τ Boo, HD 33608, and α CrB to PHOENIX models and carry out basic spectral modeling based on Voigt line profiles. Results: The intercomparison between τ Boo and HD 33608 reveals that the difference in the line depth is 6.85 ± 1.48 mÅ at the DIB location which is, however, unlikely to be caused by DIB absorption. The comparison between PHOENIX models and observed spectra yields an upper limit of 34.0 ± 0.3 mÅ for any additional interstellar absorption in τ Boo; similar results are obtained for HD 33608 and α CrB. For all objects we derive unrealistically large values for the radial velocity of any presumed interstellar clouds. In τ Boo we find Na D absorption with an equivalent width of 0.65 ± 0.07 mÅ and 2.3 ± 0.1 mÅ in the D2 and D1 lines. For the other Na, absorption of the same magnitude could only be detected in the D2 line. Our comparisons between model and data show that the interstellar absorption toward τ Boo is not abnormally high. Conclusions: We find no significant DIB absorption in any of our target stars. Any differences between modeled and observed spectra are instead attributable to inaccuracies in the stellar atmospheric modeling than to DIB absorption. The spectra are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A20

Hydrothermal assisted decoration of NiS2 and CoS nanoparticles on the reduced graphene oxide nanosheets for sunlight driven photocatalytic degradation of azo dye: Effect of background electrolyte and surface charge.

PubMed

Borthakur, Priyakshree; Das, Manash R

2018-04-15

The semiconductor NiS 2 nanoparticles with an average size of 10 ± 0.317 nm were successfully deposited on the reduced graphene oxide (rGO) sheets by simple hydrothermal method. The synthesized nanocomposite was characterized by various instrumental techniques like XRD, FTIR, FESEM, EDX, HRTEM, fluorescence spectrophotometer analysis. In this study we mainly focus on the determination of the surface potential values of NiS 2 -rGO and CoS-rGO nanocomposite under different experimental conditions and evaluated the photodegradation efficiency towards azo dye Congo Red (CR) molecule under natural sunlight irradiation. We found that the surface charge (zeta potential) of the both nanocomposite materials in presence of different inorganic ions salt solutions like NaCl, NaNO 3 , Na 2 SO 4 , MgCl 2 , CaCl 2 etc. is varied based on the polarizability of the ions as well as pH of the suspension. Different inorganic ions present in the catalyst suspension can alter the surface charge of the catalyst by forming a double layer around the molecule and thus change the electrostatic interaction between the dye molecule and the catalyst surface which change the degradation efficiency of the photocatalyst towards CR molecule. The photocatalytic efficiency of NiS 2 -rGO and CoS-rGO nanocomposite towards CR degradation was found to be 97.03% and 88.03% in 40 min, respectively under same experimental condition whereas NiS 2 and CoS nanoparticles without support exhibited photodegradation efficiency 57.89% and 50.52%, respectively. The observed improved photocatalytic activity of the metal sulfide-rGO nanocomposite results the presence of synergistic effect between the metal sulfide nanoparticles and the rGO sheets of the photocatalysts which inhibits the recombination rate of photogenerated electrons and holes. The mechanism of the degradation process was investigated by photoluminescence study in presence of terephthalic acid and also quenching experiment in presence of isopropanol and benzoquinone. The photocatalyst was characterized after degradation process and found that the crystallinity and the morphology of the nanocomposite remained unchanged. The ion-chromatography experiment confirms the formation of non-toxic products after degradation. The present study focuses on the importance of the use of metal sulphide-rGO nanocomposite towards environment remediation process and study of the influence of inorganic salts on the surface charge of the photocatalyst as well as on the degradation process. Copyright © 2018 Elsevier Inc. All rights reserved.

Cognate clinopyroxene from Paleogene mantle xenolith-bearing basanite lavas (East Serbia, SE Europe): the role of dissolution of mantle orthopyroxene

NASA Astrophysics Data System (ADS)

Cvetković, Vladica; Erić, Suzana; Radivojević, Maša; Šarić, Kristina

2012-11-01

The study focuses on clinopyroxene from mantle xenolith-bearing East Serbian basanites and suggests that dissolution of mantle orthopyroxene played an important role in at least some stages of the crystallization of these alkaline magmas. Five compositional types of clinopyroxene are distinguished, some of them having different textural forms: megacrysts (Type-A), green/colourless-cored phenocrysts (Type-B), overgrowths and sieve-textured cores (Type-C), rims and matrix clinopyroxene (Type-D), and clinopyroxene from the reaction rims around orthopyroxene xenocrysts (Type-E). Type-A is high-Al diopside that probably crystallized at near-liquidus conditions either directly from the host basanite or from compositionally similar magmas in previous magmatic episodes. Type-B cores show high VIAl/IVAl≥1 and low Mg# of mostly <75 and are interpreted as typical xenocrysts. Type-C, D and E are interpreted as typical cognate clinopyroxene. Type-D has Mg#<78, Al2O3 = 6-13 wt.%, TiO2 = 1.5-4.5 wt.%, and Na2O = 0.4-0.8 wt.% and compositionally similar clinopyroxene is calculated by MELTS as a phase in equilibrium with the last 30 % of melt starting from the average host lava composition. Type-C has Mg# = 72-89, Al2O3 = 4.5-9.5 wt.%, TiO2 = 1-2.5 wt.%, Na2O = 0.35-1 wt.% and Cr2O3 = 0.1-1.5 wt.%. This clinopyroxene has some compositional similarities to Type-E occurring exclusively around mantle orthopyroxene. Cr/Al vs Al/Ti and Cr/Al vs Na/Ti plots revealed that Type-C clinopyroxene can crystallize from a mixture of the host basanite magma and 2-20 wt.% mantle orthopyroxene. Sieve-textured Type-C crystals show characteristics of experimentally produced skeletal clinopyroxene formed by orthopyroxene dissolution suggesting that crystallization of Type-C was both texturally and compositionally controlled by orthopyroxene breakdown. According to FeO/MgOcpx/melt modelling the first clinopyroxene precipitating from the host basanite was Type-A (T ~ 1250 °C, p ~ 1.5 GPa). Dissolution of orthopyroxene produced decreasing FeO/MgOmelt and crystallization of Type-E and sieve-textured Type-C clinopyroxene (0.3-0.8 GPa and 1200-1050 °C). The melt composition gradually shifted towards higher FeO/MgOmelt ratios precipitating more evolved Type-C and Type-D approaching near-solidus conditions (<0.3 GPa; ~950 °C).

Micromonospora halotolerans sp. nov., isolated from the rhizosphere of a Pisum sativum plant.

PubMed

Carro, Lorena; Pukall, Rüdiger; Spröer, Cathrin; Kroppenstedt, Reiner M; Trujillo, Martha E

2013-06-01

A filamentous actinomycete strain designated CR18(T) was isolated on humic acid agar from the rhizosphere of a Pisum sativum plant collected in Spain. This isolate was observed to grow optimally at 28 °C, pH 7.0 and in the presence of 5 % NaCl. Phylogenetic analyses based on the 16S rRNA gene sequence indicated a close relationship with the type strains of Micromonospora chersina and Micromonospora endolithica. A further analysis based on a concatenated DNA sequence stretch of 4,523 bp that included partial sequences of the atpD, gyrB, recA, rpoB and 16S rRNA genes clearly differentiated the new strain from recognized Micromonospora species compared. DNA-DNA hybridization studies further supported the taxonomic position of strain CR18(T) as a novel genomic species. Chemotaxonomic analyses which included whole cell sugars, polar lipids, fatty acid profiles and menaquinone composition confirmed the affiliation of the new strain to the genus Micromonospora and also highlighted differences at the species level. These studies were finally complemented with an array of physiological tests to help differentiate between the new strain and its phylogenetic neighbours. Consequently, strain CR18(T) (= CECT 7890(T) = DSM 45598(T)) is proposed as the type strain of a novel species, Micromonospora halotolerans sp. nov.

Modification of tooth and enamel characteristics following the Er,Cr:YSGG laser treatment

NASA Astrophysics Data System (ADS)

Suhaimi, Fatanah M.; Aziz, N. Afifah; Jaafar, M. S.; Azizan, Nur Syazana; Zali, Nurulakma; Razak, N. A. Abd

2016-12-01

Lasers have been widely used in the dental field to treat a number of applications in dentistry. The main objective of this study is to analyse the modification of tooth composition following the Er,Cr:YSGG laser procedure. In this study, human premolar teeth were collected and prepared. The samples were sectioned and molded. 3M Unitek Transbond™ Plus Self Etching Primer adhesive materials were applied to the tooth surface. Er,Cr:YSGG laser with a wavelength of 2790 nm was used in this study to remove the adhesive materials on the enamel surface. The irradiation process was done with four different output powers that are 0.25, 0.5, 0.75, and 1.0 W. The change of tooth characteristics was analysed by observing the morphology of the enamel surface and the elemental composition usinga Field Emission Scanning Electron Microscope (FESEM) and Electron Dispersive X-ray Spectrometer (EDX). Calcium (Ca), phosphorus (P), sodium (Na), oxygen (O), and carbon (C) were the elementsidentified by EDX in the samples. Additionally, oxygen was the most abundant element found in the sample. The level of oxygen composition decreased after laser irradiation while the carbon element increased. Another element, calcium was found to be decreasing due to the process of applying adhesive materials on the enamel surface.

Transfer parameters for ICRP's Reference Animals and Plants in a terrestrial Mediterranean ecosystem.

PubMed

Guillén, J; Beresford, N A; Baeza, A; Izquierdo, M; Wood, M D; Salas, A; Muñoz-Serrano, A; Corrales-Vázquez, J M; Muñoz-Muñoz, J G

2018-06-01

A system for the radiological protection of the environment (or wildlife) based on Reference Animals and Plants (RAPs) has been suggested by the International Commission on Radiological Protection (ICRP). To assess whole-body activity concentrations for RAPs and the resultant internal dose rates, transfer parameters are required. However, transfer values specifically for the taxonomic families defined for the RAPs are often sparse and furthermore can be extremely site dependent. There is also a considerable geographical bias within available transfer data, with few data for Mediterranean ecosystems. In the present work, stable element concentrations (I, Li, Be, B, Na, Mg, Al, P, S, K. Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Cs, Ba, Tl, Pb and U) in terrestrial RAPs, and the corresponding whole-body concentration ratios, CR wo , were determined in two different Mediterranean ecosystems: a Pinewood and a Dehesa (grassland with disperse tree cover). The RAPs considered in the Pinewood ecosystem were Pine Tree and Wild Grass; whereas in the Dehesa ecosystem those considered were Deer, Rat, Earthworm, Bee, Frog, Duck and Wild Grass. The CR wo values estimated from these data are compared to those reported in international compilations and databases. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Eclogite-facies guyanaite, carmichaelite and eskolaite in xenoliths of Cr-omphacitite from Navajo diatremes, Utah: Hydration and dehydration in the subducted Farallon plate

NASA Astrophysics Data System (ADS)

Schulze, D. J.; Helmstaedt, H.

2013-12-01

The mantle-derived xenolith suite in the Navajo serpentinized ultramafic diatremes includes low-temperature metamorphic rocks such as lawsonite- and phengite-bearing eclogites, Cr-pyrope xenocrysts with inclusions of hydrous minerals and hydrated peridotites and pyroxenites containing minerals such as chlorite, pargasite, tremolite and antigorite. We have now also identified a suite of bright green Cr-rich clinopyroxenites from the Moses Rock and Mule's Ear diatremes that contain unusual assemblages of dark to opaque accessory minerals such as guyanaite [CrOOH], carmichaelite [(Ti,Cr)2-x(OH)x], eskolaite [Cr2O3], chromite and rutile. The xenoliths are dominated by omphacitic pyroxenes (most in the range 10-55 mole% jadeite) that are locally enriched in Cr adjacent to clots of accessory minerals (to 35 mole% kosmochlor). Most samples have small clusters of scattered accessory minerals (individual grains on the scale of tens of microns) but one sample has clusters to 2 mm dominated by guyanaite blades intergrown with Cr-rich omphacite. Thin grains of eskolaite traverse the guyanaite and occur at the guyanaite-omphacite interfaces. Patches of zincian chromite (to 5.7 wt% ZnO) are associated with some of the guyanaite-dominated clusters and consist of lamellar intergrowths of two texturally and compositionally different types of chromite, interpreted as an exsolution feature and precursor to hydration and metasomatic development of guyanaite-omphacite intergrowths. Minor carmichaelite occurs in these clusters. In another sample carmichaelite with finely intergrown patches of rutile dominates the clusters. Equilibration conditions of these assemblages are poorly constrained, but the reaction guyanaite = eskolaite + H2O (Jahn et al., Eur. J. Min., 2012) is consistent with an estimate for equilibration conditions of a phengite eclogite (700oC, 3.4GPa - Smith et al., GGG, 2013). We interpret these rocks to be Na-metasomatized and hydrated basalts (small clusters) and peridotites (clusters to 2mm), formed in serpentinites during subduction of the Farallon Plate under the Colorado Plateau in Laramide time, based on similarities with subduction-origin Cr-jade bodies associated with serpentinites (e.g., Myanmar). At the time of entrainment in the host diatremes, these rocks were undergoing dehydration reactions (guyanaite to eskolaite, carmichaelite to rutile) providing water to the overlying subcrustal mantle section and contributing to Plateau uplift. The occurrence of carmichaelite as inclusions armoured within pyrope garnet xenocrysts from the nearby Garnet Ridge diatreme is now linked to the presence of carmichaelite in the open system of the upper mantle in these Cr-omphacitites (the only two known occurrences of carmichaelite), complicating interpretation of the pyropes as being derived from subcontinental upper mantle formed by Proterozoic subduction.

Forsterite-Anorthite-CaTschermak-Enstatite (FACE): A geobarometer for plagioclase-bearing peridotites

NASA Astrophysics Data System (ADS)

Fumagalli, P.; Borghini, G.; Rampone, E.; Poli, S.

2017-12-01

Plagioclase peridotites can be the result of either metamorphic recrystallization, or diffuse melt-rock interactions. Although they represent an important geodynamic marker of shallow mantle exhumation, the accurate estimation of their barometric evolution is poorly constrained. Systematic correlations between pressure and composition of coexisting minerals within the plagioclase stability field have been reported in previous experimental studies. In this experimental study we present new constraints on the stability of plagioclase as a function of different Na2O/CaO bulk ratios, and we present a new geobarometer for mantle rocks. Experiments have been performed in a single-stage piston cylinder at 5-10 kbar, 1050-1150 °C at nominally anhydrous conditions using seeded gels of peridotite compositions (Na2O/CaO = 0.08-0.13; XCr = Cr/(Cr + Al) = 0.07-0.10). As expected, the increase of the bulk Na2O/CaO extends the plagioclase stability to higher pressure; in the Na2O enriched fertile lherzolite the plagioclase-spinel transition occurs between 9 and 10 kbar, 1100 °C; in the fertile lherzolite with Na2O/CaO = 0.08, it occurs between 8 and 9 kbar, 1100 °C. The present data together with previous experimental results provide a consistent database, covering a wide range of P-T conditions (3-9 kbar, 1000-1150 °C) and variable bulk compositions to be used to define and calibrate a geobarometer for plagioclase-bearing mantle rocks. We have empirically calibrated by least squares regression analysis of experimental data combined with MonteCarlo simulation the following pressure sensitive equilibrium: Mg2SiO4 Ol + CaAl2Si2O8 Pl = CaAl2SiO6 Cpx + Mg2Si2O6 OpxForsterite Anorthite Ca-Tschermak Enstatite We derive the following equation: P = 7.2 (±2.9) + 0.0078 (±0.0021) T + 0.0022 (±0.0001) T lnK R2= 0.93 where P is expressed in kbar and T in kelvin. K is the equilibrium constant K = aCa-Ts*aen / aan *afo, where aCaTs, aen, aan and afo are the activities of Ca-Tschermak in clinopyroxene, enstatite in orthopyroxene, anorthite in plagioclase and forsterite in olivine. The proposed geobarometer for plagioclase peridotites, coupled to detailed microstructural and mineral chemistry investigations, represents a valuable tool to track the exhumation of the lithospheric mantle at extensional environments.

Corrosion behavior and microstructures of experimental Ti-Au alloys.

PubMed

Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu; Okabe, Toru

2004-06-01

Anodic polarization was performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and microstructures of cast Ti-Au (5-40%) alloys. An abrupt increase in the current density occurred at approximately 0.6 V vs. SCE for the 30% and 40% Au alloys in the 0.9% NaCl solution. The microstructures after corrosion testing indicated that this breakdown may have been caused by the preferential dissolution of the Ti3Au. However, the potential for preferential dissolution was higher than the breakdown potential of stainless steel or Co-Cr alloy, which meant that the corrosion resistance of the Ti-Au alloys was superior. In 1% lactic acid solution, the corrosion resistance of the Ti-Au alloys was excellent, with no breakdown at any composition. In the present test solutions, the Ti-Au alloys up to 20% Au had good corrosion resistance comparable to that for pure titanium.

Solid state of CG-400549, a novel FabI inhibitor: characterization, dissolution, transformation.

PubMed

Kim, Bo-Yeon; Sohn, Young-Taek

2011-05-01

The polymorphic and pseudopolymorphic forms of CG-400549, a novel FabI inhibitor with potent in vivo activity were prepared and characterized by differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TG). Seven crystal forms of CG-400549, one anhydrate and six solvates, have been isolated by recrystallization and the DSC and PXRD patterns of the seven crystal forms of CG-400549 were different respectively. The dissolution patterns of these seven crystal forms of CG-400549 were studied and they showed significant differences in the dissolution rate. After storage of 1 month at 0% RH (silica gel, 20°C), 52% RH (saturated solution of Na(2)Cr(2)O(7)2H(2)O/20°C) and 95% RH (saturated solution of Na(2)HPO(4)/20°C), all crystal forms were not transformed.

VizieR Online Data Catalog: DIB and NaD spectra of 3 nearby stars (Kohl+, 2016)

NASA Astrophysics Data System (ADS)

Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

2016-05-01

The present data collection contains coadded spectra of tau Boo, HD 33608 and alpha CrB. This data was used to obtain the equivalent widths of interstellar features. The spectra show the wavelength regions around the Na D lines and around 5780Å. The latter location corresponds to a wavelength range where a strong diffuse interstellar band (DIB) is found in the spectrum of the early-type supergiant HD 183143. Each single spectrum has been corrected for telluric absorption and the wavelength axis has been shifted to the barycentric reference frame. However, the data has not been corrected for radial velocity of the star. The spectra have been acquired at the 1.2m Tigre telescope located in La Luz, Mexico. The spectral resolution of the HEROS spectrograph is 20000. A detailed description of the spectra is given in the aforementioned paper. (2 data files).

Adsorption and co-precipitation behavior of arsenate, chromate, selenate and boric acid with synthetic allophane-like materials.

PubMed

Opiso, Einstine; Sato, Tsutomu; Yoneda, Tetsuro

2009-10-15

Pollution caused by boric acid and toxic anions such as As(V), Cr(VI) and Se(VI) is hazardous to human health and environment. The sorption characteristics of these environmentally significant ionic species on allophane-like nanoparticles were investigated in order to determine whether allophane can reduce their mobility in the subsurface environment at circum-neutral pH condition. Solutions containing 100 or 150 mmol of AlCl(3)x6H(2)O were mixed to 100 mmol of Na(4)SiO(4) and the pH were adjusted to 6.4+/-0.3. The mineral suspensions were shaken for 1h and incubated at 80 degrees C for 5 days. Appropriate amounts of As, B, Cr and Se solutions were added separately during and after allophane precipitation. The results showed that As(V) and boric acid can be irreversibly fixed during co-precipitation in addition to surface adsorption. However, Cr(VI) and Se(VI) retention during and after allophane precipitation is mainly controlled by surface adsorption. The structurally fixed As(V) and boric acid were more resistant to release than those bound on the surface. The sorption characteristics of oxyanions and boric acid were also influenced by the final Si/Al molar ratio of allophane in which Al-rich allophane tend to have higher uptake capacity. The overall results of this study have demonstrated the role of allophane-like nanoparticles and the effect of its Si/Al ratio on As, B, Cr and Se transport processes in the subsurface environment.

Hydrogen Environment Assisted Cracking of Modern Ultra-High Strength Martensitic Steels

NASA Astrophysics Data System (ADS)

Pioszak, Greger L.; Gangloff, Richard P.

2017-09-01

Martensitic steels (Aermet®100, Ferrium®M54™, Ferrium®S53®, and experimental CrNiMoWV at ultra-high yield strength of 1550 to 1725 MPa) similarly resist hydrogen environment assisted cracking (HEAC) in aqueous NaCl. Cracking is transgranular, ascribed to increased steel purity and rare earth addition compared to intergranular HEAC in highly susceptible 300M. Nano-scale precipitates ((Mo,Cr)2C and (W,V)C) reduce H diffusivity and the K-independent Stage II growth rate by 2 to 3 orders of magnitude compared to 300M. However, threshold K TH is similarly low (8 to 15 MPa√m) for each steel at highly cathodic and open circuit potentials. Transgranular HEAC likely occurs along martensite packet and {110}α'-block interfaces, speculatively governed by localized plasticity and H decohesion. Martensitic transformation produces coincident site lattice interfaces; however, a connected random boundary network persists in 3D to negate interface engineering. The modern steels are near-immune to HEAC when mildly cathodically polarized, attributed to minimal crack tip H production and uptake. Neither reduced Co and Ni in M54 and CrNiMoWV nor increased Cr in S53 broadly degrade HEAC resistance compared to baseline AM100. The latter suggests that crack passivity dominates acidification to widen the polarization window for HEAC resistance. Decohesion models predict the applied potential dependencies of K TH and d a/d t II with a single-adjustable parameter, affirming the importance of steel purity and trap sensitive H diffusivity.

Influence of temperature on Yb:YAG/Cr:YAG microchip laser operation

NASA Astrophysics Data System (ADS)

Šulc, Jan; Eisenschreiber, Jan; Jelínková, Helena; Nejezchleb, Karel; Å koda, Václav

2017-02-01

The goal of this work was an investigation of the temperature influence (in range from 80 up to 320 K) on the laser properties of Yb:YAG/Cr:YAG Q-switched diode-pumped microchip laser. This laser was based on monolith crystal (diameter 3mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3mm long) and saturable absorber (Cr:YAG crystal, 1.36mm long, initial transmission 90% @ 1031 nm). The laser resonator pump mirror (HT for pump radiation, HR for generated radiation) was directly deposited on the Yb:YAG monolith part. The output coupler with reflection 55% for the generated wavelength was placed on the Cr:YAG part. The microchip laser was placed in the temperature controlled cupreous holder inside vacuum chamber of the liquid nitrogen cryostat. For Yb:YAG part longitudinal pulsed pumping (pumping pulse length 2.5 ms, rep-rate 20 Hz, power amplitude 21W) a fibre coupled (core diameter 400 μm, NA= 0:22) laser diode, operating at wavelength 933 nm, was used. The microchip laser mean output power, pulse duration, repetition rate, emission wavelength, and laser beam profile were measured in dependence on temperature. The generated pulse length was in range from 2.2 ns to 1.1 ns (FWHM) with the minimum at 230 K. The single pulse energy was peaking (0.4 mJ) at 180 K. The highest peak power (325 kW) was obtained at 220 K. The highest pulse repetition rate (38 kHz) and output mean power (370mW) was reached for temperature 80 K.

[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.

Spectroscopic studies of different brands of cigarettes using laser-induced breakdown spectroscopy

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

Sayyad, M. H.; Saleem, M.; Shah, M.

In this work the technique of laser-induced breakdown spectroscopy (LIBS) has been used for the elemental analysis of cigarettes. For this purpose emission spectra have been measured of eleven different kinds of cigarette brands sold and/or produced in Pakistan. Analysis of the spectral peaks observed shows that Na, Mg, Al, K, Ca, Cr, Fe, Sr and Ba are contained in all brands. Exhibiting the LIBS results, the powerful potential of this method for the identification of the elemental content of cigarettes is demonstrated.

Spectroscopic studies of different brands of cigarettes using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Sayyad, M. H.; Saleem, M.; Shah, M.; Shaikh, N. M.; Baig, M. A.

2008-05-01

In this work the technique of laser-induced breakdown spectroscopy (LIBS) has been used for the elemental analysis of cigarettes. For this purpose emission spectra have been measured of eleven different kinds of cigarette brands sold and/or produced in Pakistan. Analysis of the spectral peaks observed shows that Na, Mg, Al, K, Ca, Cr, Fe, Sr and Ba are contained in all brands. Exhibiting the LIBS results, the powerful potential of this method for the identification of the elemental content of cigarettes is demonstrated.

Corrosion behavior of austenitic steels and their components in niobium-containing chloride melts

NASA Astrophysics Data System (ADS)

Abramov, A. V.; Polovov, I. B.; Rebrin, O. I.; Volkovich, V. A.; Lisienko, D. G.

2014-02-01

The mechanism of corrosion of austenitic steels 12Kh18N10T, 10Kh17N13M2T, and 03Kh17N14M3 and metals Cr, Fe, Ni, and Mo in a NaCl-KCl-NbCl n ( n = 3.5, Nb content is 5 ± 0.1 wt %) melt at 750°C is studied. The metal and steel corrosion rates under these conditions are determined. The character of material fracture and the mechanisms of material corrosion are found.

Defense AT And L Magazine. Vol. 47, No. 1, January February 2018

DTIC Science & Technology

2018-01-01

available for em - ployees at all levels to engage with DoD personnel in a non- competitive, structured educational environment. Miscom- munication can...medical, fire, bomb , cyber attack, bio/ chem/rad) • Kidnap/ransom • Infrastructure • Power redundancy • Facilities hardening • Perimeter security...aly sis Th rea ts/ Ha za rd s Ris k i de nt ic ati on Mi tig ati on Em erg en cy op era tio ns Fu nc tio na l re sp on sib ilit ies Cr itic al fun

Occurrence of rhombic prisms in some structures

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

Nyman, H.

1976-02-01

An ideal rhombic prism is defined as two regular trigonal prisms sharing a square face. In terms of such rhombic prisms, the structures of CrB and ..cap alpha..-PdCl/sub 2/, U/sub 3/Si/sub 2/ and Au/sub 3/Zn, and CoCa/sub 3/ and PdS are easily described. A network of rhombic prisms, with cubic symmetry, is also used to describe the structures of CoAs/sub 3/, Sc(OH)/sub 3/, WAl/sub 12/, and NaMn/sub 7/O/sub 12/.

Determination of palladium and platinum by atomic absorption

USGS Publications Warehouse

Schnepfe, M.M.; Grimaldi, F.S.

1969-01-01

Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

A Coherent Fused Silica Fiberoptic Array.

DTIC Science & Technology

1986-07-01

7 AD-R I? 09 3 COHERENT FUSED SILIC FIBEROPTIC ARR AY(U) O ALILED / ELECTRa-OPTICS CORP STURBRIDGE MR J E ROURKE ET AL. JUL 86 ORL-CR-557 DAAIKiS...7. AUTHOR(a) 6. CONTRACT OR GRANT NUMUER(a) J. Edward Rourke * Dean J. Geraci Mark L. DeLong DAAA15-85- C -Olll 9. PERFORMING ORGANIZATION NAME AND...3r.4 c Le o COL 0) * EE >0 a) LL 141 opposite end. A variation of light intensity vs. angular position was approximately Gaussian. The NA is

Nanoscale structure in AgSbTe2 determined by diffuse elastic neutron scattering

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

Specht, Eliot D; Ma, Jie; Delaire, Olivier A

2015-01-01

Diffuse elastic neutron scattering measurements confirm that AgSbTe2 has a hierarchical structure, with defects on length scales from nanometers to microns. While scattering from mesoscale structure is consistent with previously-proposed structures in which Ag and Sb order on a NaCl lattice, more diffuse scattering from nanoscale structure suggests a structural rearrangement in which hexagonal layers form a combination of (ABC), (ABA), and (AAB) stacking sequences. The AgCrSe2 structure is the best-fitting model for the local atomic arrangements.