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Sample records for dichromates

  1. Phase holograms in dichromated gelatin.

    PubMed

    Shankoff, T A

    1968-10-01

    The gelatin-dichromate photosensitive system has been shown to be very efficient as a recording medium for both two- and three-dimensional holographic gratings. Upon development, as much as 33% of incident reading light is diffracted into the first order for the unmodulated thin phase gratings and 95% for the thick holograms. The material can record a grating spacing at least as small as 2600 A, and gives reconstructions comparable with those obtained in 649F film. The air-gelatin index differential of 0.54 is considered responsible for the high diffracted powers found. Exposures vary from 3 mJ to 150 mJ at 4880 A. Certain films have speeds within two orders of magnitude of 649F holographic film. PMID:20068941

  2. Diamond Head Revisited with Ammonium Dichromate.

    ERIC Educational Resources Information Center

    Arrigoni, Edward

    1981-01-01

    The classroom demonstration using ammonium dichromate to simulate a volcanic eruption can be modified into a more dramatic and accurate representation of the geologic processes involved in the formation of a volcanic crater. The materials, demonstration setup, safety procedures, and applications to instruction are presented. (Author/WB)

  3. Simplified dichromated gelatin hologram recording process

    NASA Technical Reports Server (NTRS)

    Georgekutty, Tharayil G.; Liu, Hua-Kuang

    1987-01-01

    A simplified method for making dichromated gelatin (DCG) holographic optical elements (HOE) has been discovered. The method is much less tedious and it requires a period of processing time comparable with that for processing a silver halide hologram. HOE characteristics including diffraction efficiency (DE), linearity, and spectral sensitivity have been quantitatively investigated. The quality of the holographic grating is very high. Ninety percent or higher diffraction efficiency has been achieved in simple plane gratings made by this process.

  4. Response of aqueous dichromate and nanoclay dichromate gel dosimeters to carbon ion irradiation

    NASA Astrophysics Data System (ADS)

    Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Fukasaku, K.; Furuta, T.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2013-06-01

    We have recently reported the significant reduction of radiation product diffusion by the incorporation of clay nanoparticles into dichromate gel (DCG) dosimeters. In this work, we investigate the influence of the nanoclay addition and gelation on the MRI R1 (1/T1) image response of the dichromate dosimeter to the therapeutic carbon ion beam (12C6+ 290 MeV/u). The MRI R1 distribution in the aqueous dichromate solution well reproduces physical dose-depth distribution with a high linear-energy-transfer (LET) efficiency. The nanoclay DCG dosimeters, on the other hand, exhibit composition-dependent LET efficiency degradation, while a sharp Bragg peak can still be detected. These results indicate that the nanocomposite gel addition may induce change in the radiation-induced reaction mechanism.

  5. Ammonium dichromate poisoning: A rare cause of acute kidney injury

    PubMed Central

    Radhakrishnan, H.; Gopi, M.; Arumugam, A.

    2014-01-01

    Ammonium dichromate is an inorganic compound frequently used in screen and color printing. Being a strong oxidizing agent, it causes oxygen free radical injury resulting in organ failure. We report a 25-year-old female who presented with acute kidney injury after consumption of ammonium dichromate. She was managed successfully with hemodialysis and supportive measures. This case is reported to highlight the toxicity of ammonium dichromate. PMID:25484533

  6. Sodium dichromate expedited response action assessment

    SciTech Connect

    Not Available

    1993-09-01

    The US Environmental Protection Agency (EPA) and Washington Department of Ecology (Ecology) recommended that the US Department of Energy (DOE) perform an expedited response action (ERA) for the Sodium Dichromate Barrel Disposal Landfill. The ERA lead regulatory agency is Ecology and EPA is the support agency. The ERA was categorized as non-time-critical, which required preparation of an engineering evaluation and cost analysis (EE/CA). The EE/CA was included in the ERA proposal. The EE/CA is a rapid, focused evaluation of available technologies using specific screening factors to assess feasibility, appropriateness, and cost. The ERA goal is to reduce the potential for any contaminant migration from the landfill to the soil column, groundwater, and Columbia River. Since the Sodium Dichromate Barrel Disposal Landfill is the only waste site within the operable unit, the removal action may be the final remediation of the 100-IU-4 Operable Unit. This ERA process started in March 1992. The ERA proposal went through a parallel review process with Westinghouse Hanford Company (WHC), DOE Richland Operations (RL), EPA, Ecology, and a 30-day public comment period. Ecology and EPA issued an Action Agreement Memorandum in March 1993 (Appendix A). The memorandum directed excavation of all anomalies and disposal of the collected materials at the Hanford Site Central Landfill. Primary field activities were completed by the end of April 1993. Final waste disposal of a minor quantity of hazardous waste was completed in July 1993.

  7. Real-time and postprocessing holographic effects in dichromated pullulan.

    PubMed

    Savić, Svetlana; Pantelić, Dejan; Jakovijević, Dragica

    2002-08-01

    Experimental results concerning both real-time and postprocessing (after-development) behavior of a novel photosensitive material, dichromate-sensitized pullulan (DCP), are investigated. The exposure mechanism and possibilities for controlling holographic grating properties are discussed. We have shown that it is possible to maximize the diffraction efficiency of interference gratings after development by controlling diffraction efficiency in real time. Stronger real-time effects of DCP compared with those of dichromated gelatin are achieved. PMID:12153075

  8. New self developed holographic media-dichromated gelatin with isopropanol

    NASA Astrophysics Data System (ADS)

    Malov, Alexander N.; Neupokoeva, Anna V.

    2007-01-01

    The gel-colloidal dichromated gelatin emulsions properties doped by different multyatoms spirits are investigated. The highest diffraction efficiency results turn out at use isopropanol spirit (IPS) for dichromated gelatin (DG) gel. Influence of the IPS on holographic properties of such layers is investigated. Optimum IPS concentration depends on gelatin concentration and makes 5 vol % for 3 % gelatin water emulsion and 10 vol % for 10 % gelatin one. Optimum IPS concentration is approximately 100 % on dry gelatin weight. DG gel with IPS photoreaction speed is increased in 5-6 times in comparison with a layer without spirit and done approximately identical to layers with glycerin.

  9. Holographic gratings in dichromated gelatin with edible dyes

    NASA Astrophysics Data System (ADS)

    Olivares-Pérez, Arturo; Fuentes-Tapia, Israel; Jauregui-Sanchez, Yessenia; Toxqui-Lopez, Santa; Juárez-Néstor, Rosario

    2015-03-01

    We present preliminary results on diffraction gratings made with holographic techniques using dichromated gelatin (DCG) matrix with edible dyes, the purple red, Layar® and blue Sabofrut®. The gratings were recorded with a laser diode, λ = 530nm. Curves show diffracted intensity vs exposure time. The recorded gratings show different diffraction efficiencies of gratings prepared with DCG, purple red + DCG, and blue+ DCG. We observed high diffraction efficiency with purple red. All exposure conditions and reconstruction were therefor for all gratings with the same concentration of dichromate for each one of the photosensitive emulsions prepared.

  10. 40 CFR 415.120 - Applicability; description of the potassium dichromate production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... potassium dichromate production subcategory. 415.120 Section 415.120 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.120 Applicability; description of the potassium dichromate production subcategory. The provisions of this subpart are applicable to discharges...

  11. 40 CFR 415.120 - Applicability; description of the potassium dichromate production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... potassium dichromate production subcategory. 415.120 Section 415.120 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.120 Applicability; description of the potassium dichromate production subcategory. The provisions of this subpart are applicable to discharges...

  12. 40 CFR 415.120 - Applicability; description of the potassium dichromate production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... potassium dichromate production subcategory. 415.120 Section 415.120 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.120 Applicability; description of the potassium dichromate production subcategory. The provisions of this subpart are applicable to discharges...

  13. 40 CFR 415.120 - Applicability; description of the potassium dichromate production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... potassium dichromate production subcategory. 415.120 Section 415.120 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.120 Applicability; description of the potassium dichromate production subcategory. The provisions of this subpart are applicable to discharges...

  14. 40 CFR 415.120 - Applicability; description of the potassium dichromate production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... potassium dichromate production subcategory. 415.120 Section 415.120 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.120 Applicability; description of the potassium dichromate production subcategory. The provisions of this subpart are applicable to discharges...

  15. 40 CFR 415.170 - Applicability; description of the sodium dichromate and sodium sulfate production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... sodium dichromate and sodium sulfate production subcategory. 415.170 Section 415.170 Protection of... MANUFACTURING POINT SOURCE CATEGORY Sodium Dichromate and Sodium Sulfate Production Subcategory § 415.170 Applicability; description of the sodium dichromate and sodium sulfate production subcategory. The provisions...

  16. Tests Of Polyurethane And Dichromate Coats On Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Report describes experiments to determine relative effectiveness of new polyurethane and more-conventional dichromate coat in helping to retard corrosion of anodized 6061-T6 aluminum. Concludes by suggesting greater protection against corrosion achieved by combining polyurethane-sealing method with hard-anodizing method and by increasing thickness of coat.

  17. Non-hydroscopic vanilla doped dichromated gelatin holographic material

    NASA Astrophysics Data System (ADS)

    Pinto-Iguanero, B.; Olivares-Pérez, A.; Méndez-Alvarado, A. W.; Fuentes-Tapia, I.; Treviño-Palacios, C. G.

    2003-06-01

    Dichromate gelatins are well-known holographic materials. By doping this material with synthetic vanilla a change in the spectral response from regular dichromate gelatin is observed as an increase in optical density. This mixture presents an unusual high humidity resistance. It was possible to record holographic diffraction gratings using an argon ion laser ( λ=488 nm). These gratings exhibit good diffraction efficiency in transmission, on the order of 60% at Bragg angle, with more than 1700 lines/mm spatial resolution. The material development process consists simply of dipping it into using a solution of water and isopropyl alcohol. A hypothesis on the hydroscopic response of this new photosensitive material is also presented.

  18. Sodium Dichromate Barrel Landfill expedited response action proposal

    SciTech Connect

    Not Available

    1993-09-01

    The US Environmental Protection Agency (EPA) and Washington State Department of Ecology (Ecology) recommended that the US Department of Energy (DOE) prepare an expedited response action (ERA) for the Sodium Dichromate Barrel Landfill. The Sodium Dichromate Barrel Disposal Site was used in 1945 for disposal of crushed barrels. The site location is the sole waste site within the 100-IU-4 Operable Unit. The Waste Information Data System (WIDS 1992) assumes that the crushed barrels contained 1% residual sodium dichromate at burial time and that only buried crushed barrels are at the site. Burial depth is shallow since visual inspection finds numerous barrel debris on the surface. A non-time-critical ERA proposal includes preparation of an engineering evaluation and cost analysis (EE/CA) section. The EE/CA is a rapid, focused evaluation of available technologies using specific screening factors to assess feasibility, appropriateness, and cost. The ERA goal is to reduce the potential for any contaminant migration from the landfill to the soil column, groundwater, and Columbia River. Since the landfill is the only waste site within the operable unit, the ERA will present a final remediation of the 100-IU-4 operable unit.

  19. Fish gelatin and ammonium dichromate as photosensitive film

    NASA Astrophysics Data System (ADS)

    Orozco-Muñoz, Rosa Elena; Ortiz-Gutiérrez, Mauricio; Salgado-Verduzco, Marco Antonio; Ibarra-Torres, Juan Carlos; Olivares-Pérez, Arturo; Toxqui-López, Santa; Pérez-Cortés, Mario

    2014-02-01

    In this work we propose a phase material based on fish gelatin from Norland Productsmixed with ammonium dichromate deposited on a glass substrate. The photosensitive film has 110 mm thickness. In this material we record low frequency (264 lines/mm) holographic gratings using a λ=532 nm from an Ar laser and reconstruct the image with λ=594 nm from a He-Ne laser. The diffraction efficiency is approximately15% for the first order. The material no requires developing process and is very easy to make. Experimental results are shown.

  20. Dichromated pullulan as a novel photosensitive holographic material.

    PubMed

    Panteli, D; Savi, S; Jakovljevic, D

    1998-05-15

    We found that pullulan [an a -glucan with (1?4) and (1?6) linkages] doped with chromium ions posseses promising holographic properties. It is environmentally stable and is capable of registering high spatial frequencies (as many as 1500 lines/mm) and producing surface relief. At 1000 lines/mm pullulan's diffraction efficiency was 4%. Chemical treatment of pullulan with a mixture of water and isopropyl alcohol is simple. However, as expected from analogy with dichromated gelatin, pullulan is sensitive in only the blue-green region of the spectrum. PMID:18087349

  1. Hepatoprotective effect of Taraxacum officinale leaf extract on sodium dichromate-induced liver injury in rats.

    PubMed

    Hfaiedh, Mbarka; Brahmi, Dalel; Zourgui, Lazhar

    2016-03-01

    Taraxacum officinale (L.) Weber, commonly known as Dandelion, has been widely used as a folkloric medicine for the treatment of liver and kidney disorders and some women diseases such as breast and uterus cancers. The main objective of the present study was to assess the efficiency of T. officinale leaf extract (TOE) in treating sodium dichromate hazards; it is a major environmental pollutant known for its wide toxic manifestations witch induced liver injury. TOE at a dose of 500 mg/kg b.w was orally administered once per day for 30 days consecutively, followed by 10 mg/kg b.w sodium dichromate was injected (intraperitoneal) for 10 days. Our results using Wistar rats showed that sodium dichromate significantly increased serum biochemical parameters. In the liver, it was found to induce an oxidative stress, evidenced from increase in lipid peroxidation and changes in antioxidative activities. In addition, histopathological observation revealed that sodium dichromate causes acute liver damage, necrosis of hepatocytes, as well as DNA fragmentation. Interestingly, animals that were pretreated with TOE, prior to sodium dichromate administration, showed a significant hepatoprotection, revealed by a significant reduction of sodium dichromate-induced oxidative damage for all tested markers. These finding powerfully supports that TOE was effective in the protection against sodium dichromate-induced hepatotoxicity and genotoxicity and, therefore, suggest a potential therapeutic use of this plant as an alternative medicine for patients with acute liver diseases. PMID:25270677

  2. Some principles for formation of self-developing dichromate media

    NASA Astrophysics Data System (ADS)

    Sherstyuk, Valentin P.; Malov, Alexander N.; Maloletov, Sergei M.; Kalinkin, Vyacheslav V.

    1991-02-01

    The optical information recorded in dichromate gelatin (DCG) layers Induced the information of a latent. image Which rnder the action of water and alcohols transforms to a relief or Phase image. The action of water vapours ma appreciably increase diffraction efficiency. judging from the assumPtion that the introduction of multiatomic alcohols favours the retention of water'' moecu1es in a lager in the amount sufficient for deve1oment on its exposure and stabilization of chromium complexes1 a " self-development" regim has teen worked out. In this case the diffraction efficiency of recorded hc. 1ograms is c''ose to the theoretical limiting value for flatphase r''e c o rdI ng me (J i a. At present the occurence of a Primary latent holographic image (or structure) in dichromated gelatin (DCG) layers has been recognized The diffraction efficiency (DE) detected at a step of holographic recording is low (about 0. 1-IZ). It was shown earlier /j_ 2/ that the treatment bY water vaours or eXPOSUPC Of the layers under conditions of increased humidity results ma growth of DE up to the values enabling the use of DCG to record information in real time /3/j Latent image centres in exposed DC3 layers are predominantly chromium(V) compounds. It is particulary evidenced by the observed correlation between the rate of formation of Cr(V) compounds in a Photo process and the specific change in DE of a latent image /5/.

  3. Determination of ethanol in wine by titrimetric and spectrophotometric dichromate methods: collaborative study.

    PubMed

    Pilone, G J

    1985-01-01

    A dichromate-spectrophotometric method for the determination of ethanol in wine was compared in a collaborative, matched pair study with the AOAC dichromate-titrimetric method, 11.008-11.011. Both methods require distillation of the sample into dichromate. The titrimetric method measures ethanol by titrating the excess dichromate with ferrous ammonium sulfate after conversion of ethanol to acetic acid; the spectrophotometric method directly measures the reduced dichromate formed after oxidation. In addition to comparing the 2 methods, the collaborative study also compared the use of 2 types of assemblies for obtaining the ethanol distillate: the Scott-type, which is used in 11.008-11.011, and the electric Kirk-type. Results of the collaborative study indicated that the repeatability and reproducibility of the official titrimetric method were generally far superior to those of the spectrophotometric method; therefore, adoption of the spectrophotometric method is not recommended. Comparison of titrimetric method results obtained using the 2 types of stills indicated that repeatability and reproducibility were somewhat better when Scott apparatus was used, but measurements using Kirk-type compared well in the range of ethanol concentrations found in table and fortified wines. The Kirk-type distillation apparatus has been adopted official first action as an alternative to Scott apparatus in the dichromate oxidation method for ethanol in wine, 11.008-11.011. PMID:3988696

  4. Thermodynamics and density functional theory study of potassium dichromate interaction with galena

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Hua; Long, Xian-Hao; Lan, Li-Hong; He, Qian

    2014-10-01

    The adsorption heat and reaction rate constant of potassium dichromate on the surface of galena were studied. The results indicate that potassium dichromate tends to adsorption on the galena surface. The reaction order is only 0.08385, suggesting that the concentration of potassium dichromate has little influence on its adsorption on the galena surface. In addition, the simulation of CrO{4/2-} adsorption on the PbS (100) surface in the absence and presence of O2 was carried out by density functional theory (DFT). The calculated results show that CrO{4/2-} species adsorb energetically at the Pb-S bond site, and the presence of O2 can enhance this adsorption.

  5. Study on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos.

    PubMed

    Chen, Shifu; Cao, Gengyu

    2005-09-01

    In this paper, dichromate and dichlorvos are selected as the deputies of inorganic and organic pollutants, respectively, and TiO2/beads is used as a photocatalyst. The effects of various parameters, such as the amount of the photocatalyst, H2O2 concentration, metal ions, anions, pH value, and organic compounds on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos are studied. From the studies, the differences of the parameters effect on the photocatalytic degradation of organic and inorganic pollutants are obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g cm(-3) for the photocatalytic reactions. With the addition of a small amount of H2O2, the photocatalytic reduction of dichromate is inhibited while the photocatalytic oxidation of dichlorvos is accelerated. With the addition of trace amounts of Fe3+ or Cu2+, both the reactions are accelerated, and with the addition of Zn2+ and Na+, no obvious effects on the reactions are observed. Acidic solution is favorable for the photocatalytic reduction of dichromate; and acidic and alkaline solutions are favorable for the photocatalytic oxidation of dichlorvos. Adding SO4(2-), the photocatalytic oxidation is accelerated and adding Cl- the reaction is inhibited; and with the addition of trace amounts of SO4(2-), Cl- and NO3-, no obvious effects on the photocatalytic reduction of dichromate are observed. With the addition of methanol and toluene, the photocatalytic reduction of dichromate is accelerated, and the photocatalytic oxidation of dichlorvos is inhibited. The possible roles of the additives on the reactions are also discussed. PMID:16018902

  6. The use of potassium dichromate and ethyl alcohol as blood preservatives for analysis of organochlorine contaminants.

    PubMed

    Schecter, Arnold; Pavuk, Marian; Päpke, Olaf; Malisch, Rainer

    2004-10-01

    The "gold standard" for preserving and shipping of human tissue samples for analysis of organochlorine contaminants is freezing. This method can be difficult, costly if using heavy dry ice for shipping, and often unfeasible, especially in less developed countries where electricity and dry ice are frequently rare or absent. Therefore, it is essential that more convenient and practical methods for preservation of blood samples are found. As an alternative to freezing, there have been studies employing potassium dichromate as a preservative for human or cow's milk or ethyl alcohol preservation of blood for dioxin analysis. In this study, four methods were compared to investigate the effectiveness of ethyl alcohol and potassium dichromate as blood preservatives for analysis of dioxins, dibenzofuran, and polychlorinated biphenyl (PCB) congeners. Samples of whole blood from a Dallas, Texas hospital were collected and pooled. Freezing, ethyl alcohol in two concentrations (20% and 40% per volume of sample), and potassium dichromate were used for blood preservation. The blood samples containing potassium dichromate or ethyl alcohol were stored and sent to ERGO laboratory for dioxin analysis and comparison with results from the frozen sample, which was kept frozen at all times until analyzed. This study suggests that potassium dichromate is a suitable alternative to freezing for preservation of whole blood for dioxin, dibenzofuran, and PCB measurements when either lipid or wet weight based results are reported. Potassium dichromate tablets were very easy and convenient to use--two 100 mg tablets (with a dichromate content of about 33 mg each) were added to each bottle containing 65 ml of blood. However, ethyl alcohol at 20% and 40% concentration under the conditions of this pilot study and the analytical method employed did not appear to provide satisfactory preservation when lipid based results are given or when the fat content has to be determined (wet or whole weight

  7. The Reaction between Iron(II) Iodide and Potassium Dichromate(VI) in Acidified Aqueous Solution

    ERIC Educational Resources Information Center

    Talbot, Christopher

    2013-01-01

    This "Science note" teaching lesson explores the possible reaction between the ions in a reaction mixture consisting of iron(II) iodide and potassium dichromate(VI) in acidified aqueous solution. The electrode potentials will be used to deduce any spontaneous reactions under standard thermodynamic conditions (298 K, 1 bar (approximately…

  8. Dichromate solution as a reference dosemeter for use in industrial irradiation plants

    NASA Astrophysics Data System (ADS)

    Sharpe, P. H. G.; Barrett, J. H.; Berkley, A. M.

    1982-10-01

    The radiolytic reduction of dichromate ion in aqueous solution was investigated as a dosimetry system for reference purposes in the 10 to 40 kGy range. Preliminary work showed 0.4 M sulphuric acid to be unsuitable as a solvent for dichromate and all work reported here has been carried out in 0.1 M perchloric acid solution. An initial concentration of dichromate ions of 2.5 mM was judged optimal for this dose range and measurement wavelength of 440 nm is suggested. Deviations from the Beer-Lambert law at this wavelength were investigated and extinction coefficients are reported for both dichromate ion and chromic (Cr(III)) ion. Solutions were found to be stable after irradiation, even when stored at elevated temperatures. The difference in reduction yield between batches of solution was shown to be less than + or - 0.5%. The effect of irradiation temperature on reduction yield was determined to be -0.2% per deg C over the range 20 to 50 C.

  9. Origin of the photo-cross-linking process in dichromated polyacrylamide under conventional and laser irradiation.

    PubMed

    Berger, Audrey; Frezet, Lawrence; Israëli, Yaël

    2009-10-29

    This work is devoted to determining the contribution of amide groups in the photoredox and cross-linking process of dichromated polyacrylamide based on the fate of the photoactive species and of the polymer under conventional and laser irradiation. It was shown that, in parallel to the reduction of chromium(VI) into chromium(V), the cross-linking of the matrix occurred through a complexation reaction around chromium(V) and through formation of covalent bonds between macromolecular chains. A comparison with dichromated poly(vinyl alcohol) was also reported to highlight the role of the chemical structure of the polymeric matrix in the mechanism of hologram formation. Moreover, for the first time it was demonstrated by in situ infrared spectroscopy that the physicochemical modifications undergone by the photosensitive materials were similar for the two modes of irradiation. PMID:19813708

  10. Acute ammonium dichromate poisoning in a 2 year-old child.

    PubMed

    Sunilkumar, Menon Narayanankutty; Ajith, Thekkuttuparambil Ananthanarayanan; Parvathy, Vadakut Krishnan

    2014-11-01

    Hexavalent chromium compounds are most commonly used in printing, dyeing, plastics and rayon manufacturing. Poisoning in children by ammonium dichromate, an odorless and bright orange-red crystal, are rarely reported. Acute poisoning will result in death due to multi-organ failure. The target organs that are affected by this poison are the respiratory system, kidneys, liver, eyes and skin. On ingestion, initially there is a relative lack of severe symptoms and signs. Hence, the delay in seeking medical attention could lead to the increased rate of mortality. In this case study, we report the ingestion of ammonium dichromate by a child. Despite appropriate management, such as hepatic supportive measures and plasma transfusion, the toxicity progressed to multi-organ failure and death. PMID:25425845

  11. Protective role of cactus cladodes extract on sodium dichromate-induced testicular injury and oxidative stress in rats.

    PubMed

    Hfaiedh, Mbarka; Brahmi, Dalel; Zourgui, Lazhar

    2014-06-01

    Cactus (Opuntia ficus-indica) is a xerophyte plant that belongs to the Cactaceae family. The present study was designed to investigate the possible protective effects of cactus cladodes extract (CCE) on sodium dichromate-induced testis damage in adult male Wistar rats. For this purpose, CCE at a dose of 100 mg/kg was orally administrated, followed by 10 mg/kg sodium dichromate (intraperitoneal injection). After 40 days of treatment, the rats were sacrificed, and the testes were excised for histological, lipid peroxidation (LPO), and antioxidant enzyme analyses. Sodium dichromate treatment significantly (P<0.01) decreased the body, testis, and accessory sex organ weights, sperm count and motility, and serum testosterone level. In addition, histological analysis revealed pronounced morphological alterations with tubular necrosis and reduction in the number of gametes in the lumen of the seminiferous tubules of sodium dichromate-intoxicated rats. Furthermore, exposure to sodium dichromate significantly (P<0.01) increased LPO level and decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in testis. Interestingly, pretreatment with CCE significantly (P<0.01) restored the serum testosterone level, sperm count, and motility to the levels of the control group. Moreover, CCE administration was capable of reducing the elevated level of LPO and significantly (P<0.01) increased SOD, CAT, and GPx activities in testis. Cactus cladodes supplementation minimized oxidative damage and reversed the impairment of spermatogenesis and testosterone production induced by sodium dichromate in the rat testis. PMID:24752970

  12. A glutaraldehyde/potassium dichromate tracing method for the localization and preservation of abdominal extra-adrenal chromaffin tissues.

    PubMed

    Mascorro, J A; Yates, R D; Chen, I L

    1975-11-01

    The present work introduces a method for the localization in situ of the abdominal paraganglia. After treating retroperitoneal tissue blocks with a near-neutral glutaraldehyde/potassium dichromate solution following routine glutaraldehyde perfusion, intra- and extraadrenal chromaffin tissues develop a pronounced brown color from the interaction of glutaraldehyde/potassium dichromate with amines. In this manner, visualization of the abdominal extra-adrenal chromaffin organs is enhanced at the same time that cellular ultrastructure is preserved. Subsequent examination of the dichromate-reacted tissues with the electron microscope confirms that they represent the amine-rich paraganglia. This method offers an effective alternative to extensive sampling of plastic-embedded blocks for localizing peripheral chromaffin tissue and has been used to define the exact distribution of abdominal paraganglia in the rabbit. PMID:58451

  13. Dichromated poly(vinyl alchohol)-xanthene dye systems: holographic characterization and electron spin resonance spectroscopic study

    NASA Astrophysics Data System (ADS)

    Manivannan, Gurusamy; Changkakoti, Rupak; Lessard, Roger A.; Mailhot, Gilles; Bolte, Michel

    1994-01-01

    Dichromated poly(vinyl alcohol)-xanthene dye (DCPVA-XD) systems have been employed as real-time holographic recording materials. In this paper, holographic characterization of dichromated poly(vinyl alcohol) with fluorescein (Fl), eosin Y (EY) and Rose Bengal (RB) is presented. In addition, a systematic ESR spectroscopic investigation was also performed on these systems. The photochemical evolution of Cr(V), Cr(III), polymer radical and dye radical in these systems has been monitored and a comparison is made.

  14. A novel dichromate-sensitive fluorescent nano-chemosensor using new functionalized SBA-15.

    PubMed

    Hosseini, Morteza; Gupta, Vinod Kumar; Ganjali, Mohammad Reza; Rafiei-Sarmazdeh, Zahra; Faridbod, Farnoush; Goldooz, Hassan; Badiei, Ali Reza; Norouzi, Parviz

    2012-02-17

    A novel fluorescence nano-chemosensor for Cr(2)O(7)(2-) anion has been developed by assembly of fluorescent aluminum complex of 8-hydroxyquinoline (AlQ(x)) within the channels of modified SBA-15. SBA-SPS-AlQ(x) shows a fluorescence emission at 486 nm. The observed remarkable fluorescence of SBA-SPS-AlQ(x) quenches in presence of Cr(2)O(7)(2-) anion. The results showed that this fluorescent nano-material can be a useful chemo-sensor for determination of dichromate anions in aqueous solutions. The linear detecting range of fluorescent nano-chemosensor for Cr(2)O(7)(2-) anion was 0.16-2.9 μmol L(-1). The lowest limit of detection (LDL) was also found to be 0.2 ng mL(-1) in aqueous solutions. SBA-SPS-AlQ(x) showed selectively and sensitively fluorescent quenching response toward Cr(2)O(7)(2-) ion in comparison with I(3)(-), NO(3)(-), CN(-), CO(3)(2-), Br(-), Cl(-), F(-), H(2)PO(4)(-) and SO(4)(2-) ions, which was because of the higher stability of its inorganic complex with dichromate ion. PMID:22244170

  15. Primary photochemical process in films of dichromated gelatin: a quantitative approach

    NASA Astrophysics Data System (ADS)

    Lafond, Christophe; Pizzocaro, Christine; Lessard, Roger A.; Bolte, Michele

    2000-03-01

    The photochemical behavior of dichromated gelatin films is investigated on irradiation at 365 nm and 491.6 nm. Fourier transform infrared (FTIR) spectroscopy confirms the two-step reduction of chromium (VI) into chromium (III). Prior to the irradiation, the molar extinction coefficient (epsilon) of chromium (VI) in the film is measured as a function of the pH of the starting solution with the result that (epsilon) appears to be pH independent in the range 2 to 10 contrary to what is observed in solution. Chromium (V) resulting from a charge transfer between the polymeric matrix and chromium (VI) species in the excited state appears to be surprisingly stable in the gelatin matrix. Accordingly, the subsequent slow reduction of chromium (V) into the final chromium (III) does not interfere in a significant way in chromium (VI) reduction. As a result, it is possible to determine the UV- visible spectrum of chromium (V) and to quantify its formation. So far no quantitative results were reported in the literature concerning the chromium (V) spectrum and its formation in a film of dichromated gelatin. FTIR spectroscopy confirms the two-step reduction of chromium (VI) into chromium (III).

  16. Study of skin and mucous membrane disorders among workers engaged in the sodium dichromate manufacturing industry and chrome plating industry

    PubMed Central

    Singhal, Vijay Kumar; Deswal, Balbir Singh; Singh, Bachu Narayan

    2015-01-01

    Background: Inhalation of dusts and fumes arising during the manufacture of sodium dichromate from chrome ore, chromic acid mist emitted during electroplating, and skin contact with chromate produce hazards to workers. Objectives: (1) To elucidate the prevalence of skin and mucous membrane disorders among the workers engaged in the sodium dichromate manufacturing industry and chrome plating industry. (2) To know the relationship of prevalence with the duration of exposure to chrome mist, dust, and fumes. Settings and Design: A cross-sectional study was conducted among all the workers engaged in sodium dichromate manufacturing and chrome plating from several industries situated near the Delhi-Haryana border in the districts of Faridabad and Sonepat of Haryana, India from January 01, 2014 to December 31, 2014. Materials and Methods: All the workers available from the concerned industries for the study were interviewed and medically examined after obtaining their informed consent. A total of 130 workers comprising 66 workers from the sodium dichromate manufacturing industry and 64 workers from the chrome plating industry were examined on a pretested schedule. Statistical Analysis: Descriptive statistical methods (proportions, relative risk, and Chi-square test of significance with P value analyzed using Epi Info version 7). Results: All the workers were found to be males and of the adult age group. Out of the total examined, 69.69% and 56.22% of the workers had disorders of the nasal mucous membrane in the sodium dichromate manufacturing industry and the chrome plating industry, respectively. 42.42% and 28.22% of the workers had perforation of the nasal septum in the sodium dichromate manufacturing industry and chrome plating industry, respectively. 6.06% and 3.12% workers had skin ulcers in the sodium dichromate manufacturing industry and chrome plating industry, respectively. Nasal irritation and rhinorrhea were the most commonly found symptoms in both the processes

  17. Toxicity of sodium molybdate and sodium dichromate to Daphnia magna straus evaluated in acute, chronic, and acetylcholinesterase inhibition tests.

    PubMed

    Diamantino, T C; Guilhermino, L; Almeida, E; Soares, A M

    2000-03-01

    As a result of a widespread application in numerous industrial processes, chromium is a contaminant of many environmental systems. Chromium and their compounds are toxic to both invertebrates and vertebrates and, for this reason, there has been a search for suitable and less toxic alternatives. Molybdenum compounds have been studied as alternative to chromium compounds for some industrial applications. The toxicity of chromium is well known but the effects of molybdenum and molybdenum mining on natural populations and communities of freshwater invertebrates have not often been studied. However, chromium, and molybdenum (and their compounds) are included in the same list (List II) of European Union dangerous substances. In this study, the acute and chronic effects of sodium molybdate and sodium dichromate to Daphnia magna Straus were evaluated. Furthermore, in vitro and in vivo effects of these two metals on acetylcholinesterase (AChE) activity of D. magna Straus were investigated. LC(50) values determined at 48 h were 0.29 and 2847.5 mg L(-1) for chromium (as sodium dichromate) and molybdenum (as sodium molybdate), respectively. No significant in vitro effects of both metals on AChE were found. However, both toxicants inhibited AChE in vivo at concentrations under the respective 48-h LC(50) values. Both sodium dichromate and sodium molybdate inhibited the reproduction and growth of D. magna, but the concentrations inducing significant effects were different for the two chemicals. Sodium molybdate had significant lower toxicity to D. magna Straus than sodium dichromate. PMID:10702344

  18. Kinetics of formation of holographic structure of a hologram mirror in dichromated gelatin

    NASA Astrophysics Data System (ADS)

    Kzuzhilin, Yu E.; Mel'nichenko, Yu. B.; Shilov, V. V.

    1991-02-01

    Optical spectrometry Xray diffraction and molecular light sea ttering were used to investigate the formation of holographic structure of a hologram mirx''or in a gelatin layer sensitized with ammo nium dichromate. It is shown that the intheed phase contrast of the holographic structure is formed due to rnicrophase separation o the system watergelatin-isopropanol into two polymerenrihed or sol ventenriched phases further polymer glass transition which results in the interruption of phase development and micropore formation caused by the removal of a solvent from the recording medium. Pore size distribution is determined by the density of crosslinks (mi tial and formed as a result of photochemical and dark reactions) in the bulk of the recording medium. t.

  19. Band-edge lasing in Rh6G-doped dichromated gelatin at different excitations

    NASA Astrophysics Data System (ADS)

    Ying, Cui-Feng; Zhou, Wen-Yuan; Ye, Qing; Zhang, Xiao-Liang; Tian, Jian-Guo

    2010-11-01

    One-dimensional photonic crystal band-edge lasing at different excitations was studied experimentally by altering the excitation angle. We considered almost every condition including in-band, out-of-band and near the band edge while keeping the density of states unchanged. Holographic rhodamin 6G-doped dichromated gelatin was used for creating low-threshold photonic band-edge lasing (PBEL). Lasing actions excited near the high-energy and low-energy band edges were observed simultaneously, and their full widths at half maximum were different. The results show that the PBEL intensity and pump efficiency are sensitive to the excitation angle, enhanced obviously at the excitation near the band edge and suppressed distinctly in the band which agreed well with the theoretical prediction. We also demonstrated for the first time that active matters exist not only in the air voids but also in the high-index regions of the gelatin.

  20. Holographic recording characteristics and applications of single-layer panchromatic dichromated gelatin material

    NASA Astrophysics Data System (ADS)

    Zhu, Jianhua; Xu, Min; Chen, Ligong; Guo, Yongkang; Guo, Lurong

    2005-09-01

    A high-quality single-layer panchromatic dichromated gelatin material is achieved successfully by employing new types of multi-color photosensitizers and photochemical promoters to conventional photo-crosslinking gelatin system. Its holographic recording characteristics such as spectral response, the photosensitivity of three primary colors, spectral selectivity of volume reflection hologram, angular and wavelength selectivity of volume transmission hologram, are studied in detail. Using red, green and blue lasers, namely three primary colors, the bright volume transmission and reflection holograms can be recorded on the panchromatic material at the exposure level of 30 mJ/cm2. Some preliminary results of space, angle and wavelength multiplexing holographic storage for storing multiple binary and grey-tone optical images, are also reported in this paper.

  1. Determination of total and hexavalent chromium in bile after intravenous administration of potassium dichromate in rats

    SciTech Connect

    Cavalleri, A.; Minoia, C.; Richelmi, P.; Baldi, C.; Micoli, G.

    1985-08-01

    Total and hexavalent chromium were measured in bile samples obtained from cannulated bile ducts of male rats iv administered with potassium dichromate at various doses corresponding to 0.1, 0.5, and 1 mg of chromium. The evaluation of the hexavalent form was performed by separation with a liquid anion exchanger and electrothermal atomization-atomic absorption spectrophotometric determination. Within 2 hr 1.35-2.23% of the chromium injected was recovered in bile as total chromium, the hexavalent form accounting for less than 1% of the total chromium collected, which seems almost entirely excreted as trivalent chromium. Since Cr(VI) administered iv was quickly reduced to Cr(III) in blood, the possibility exists for chromium in trivalent form to penetrate into the liver cells and to be excreted in the bile, possibly by binding to a carrier such as the low-molecular-weight substances described by Yamamoto et al.

  2. The transmission volume-phase holographic grating recorded on dichromated gelatin film used in Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Mei, Qijing; Liu, Peng; Tang, Minxue

    2015-11-01

    With the intrinsic advantages of high diffraction efficiency, signal to noise ratio, wavelength and angular selectivity, and low scattering and absorption, volume phase holographic grating (VPHG) has been widely used for spectroscopy, telecommunications, astronomy and ultra-fast laser sciences. The transmission VPHG combined with on-axis imaging lenses can be used in the Raman spectroscopic imaging, which enables a spectrometer to work at high resolution over a wide field of view, and compresses the configuration to achieve very little vignetting. The subject of this paper is to design a kind of transmission VPHG used in Raman Spectrometer with high diffraction efficiency theoretically. According to the Bragg condition and the coupled wave theory, the diffraction efficiency of transmission VPHG recorded on dichromated gelatin (DCG) has been optimized by using G-solver software, which is applicable to the visible waveband ranging from 0.46μm to 0.70μm. The effects of the recording and reconstruction setup parameters, the amplitude of the index modulation (Δn) and the thickness of the gelatin layer (d), and the polarization state of reconstruction beams on the diffraction efficiency properties of the gratings are analyzed at the same time.

  3. Radiological characteristics of charged particle interactions in the first clay-nanoparticle dichromate gel dosimeter

    NASA Astrophysics Data System (ADS)

    Taylor, M. L.; Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Fukasaku, K.; Furuta, T.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2013-06-01

    The incorporation of clay nanoparticles into gel dosimeters shows promise for significant diffusion reduction - but to what extent does the presence of the nano-clay influence charged particle interactions and, in particular, what is the impact on water equivalence? In this work, we quantify the radiological characteristics of electron, proton and carbon ion interactions in the RIKEN dichromate nanoclay gel and specifically evaluate the water equivalence over a broad energy range. Results indicate that the radiological properties are sufficiently representative of tissues that this low-diffusion gel could readily be used for validation of complex dose distributions. Electron and proton ranges are within 1 % of those in water. Mean effective atomic numbers for electron interactions in the range 10 keV - 10 GeV are within 1 % of those of water which, coupled with the similar mass density, ultimately means the overall impact on dose distributions is not great. The range of C6+ ions in the nanoclay gel is closer to that of water (< 4 %) than a common polymer gel dosimeter (< 7 %), though experimentally measured R1 values indicate an over-response at low doses.

  4. Potassium Dichromate Toxicities: Protective Effect of Methanol Extract of Corchorus olitorius in Albino Rats.

    PubMed

    Akinwumi, Kazeem A; Osifeso, Olabode O; Jubril, Afusat J; Adedoja, Ayobami W; Ogunbiyi, Elizabeth T; Adebo, Fumilayo M; Adesina, Idayat O; Odunola, Oyeronke A

    2016-05-01

    Exposure to hexavalent chromate compounds such as other human carcinogens is unavoidable in the developing countries of the world. Research efforts are being directed toward minimizing exposure to them, intercepting their activity in vivo, and/or prophylaxis. The present study therefore evaluates the effect of methanol extract of the leafy vegetable, Corchorus olitorius (MECO), against potassium dichromate (K2Cr2O7)-induced toxicities. Negative control animals were fed distilled water, while the positive control rats received 12 mg/kg body weight K2Cr2O7 once a week for 6 weeks. Test rats were exposed daily to 25, 50, and 100 mg/kg body weight MECO alone for 6 weeks and 12 mg/kg body weight of K2Cr2O7 once a week for 6 weeks before sacrifice. The frequency of micronucleated polychromatic erythrocytes (mPCEs) was monitored in bone marrow cells, while induction of aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine levels, and hematological parameters were assessed in the plasma. The phytochemical analysis of MECO was also carried out. K2Cr2O7 significantly (P < .05) increased the levels of mPCEs, AST, ALT, creatinine, total white blood cells, and lymphocytes compared with the control. The percentage pack cell volume and neutrophils were, however, reduced. In contrast, MECO at different doses restored the markers toward the levels of the negative control. MECO is rich in flavonoids, saponins, anthraquinones, terpenoids, and phenols, and they might be responsible for the protective effect observed in this study. Our results suggest that MECO has a promising potential in the treatment/management of chromate-induced toxicities. PMID:27152977

  5. Syntheses of [omega]-alkynyl aldehydes and ketones via oxidation of [omega]-alkynyl alcohols with pyridinium dichromate

    SciTech Connect

    Bierer, D.E.; Kabalka, G.W. )

    1988-01-01

    Pyridinium dichromate (PDC) is an effective reagent for the oxidation of alcohols and a number of modifications of the original procedure have been reported. Interestingly, PDC has never been used to oxidize non-conjugated acetylenic alcohols. As a part of a project involving the chemical preparation of a number of unsaturated amino acids, the authors investigated the synthesis of a series of [omega]-alkynyl aldehydes. The authors now report that the PDC oxidation of [omega]-alkynyl alcohols is an effective route to the corresponding [omega]-alkynyl carbonyl compounds.

  6. Identification of leucocyte surface antigens in paraffin-embedded bovine tissues using a modified formalin dichromate fixation.

    PubMed

    Rathkolb, B; Pohlenz, J F; Wohlsein, P

    1997-06-01

    A modified fixative of formalin dichromate was combined with a cold embedding procedure for the preservation of bovine leucocyte surface antigens. Fourteen monoclonal antibodies recognizing seven bovine leucocyte surface antigens (BoCD1w2, BoCD4, BoCD8, BoWC1, BoWC3, BoWC4 and BoIgM) were applied as primary antisera in a sensitive avidin-biotin-peroxidase complex detection method. The staining results were compared with those obtained in cryostat and routinely formalin-fixed sections of corresponding tissue samples. Using the modified formalin dichromate fixative and the cold embedding procedure, all the leucocyte surface antigens tested were detectable immunohistologically in paraffin sections with a generally more distinct staining than in traditionally processed tissues. Morphological structures were better preserved than in cryostat sections but, to some extent, were poorer when compared with routinely formalinfixed tissues. However, this method suggests that there are only mild masking effects and provides an alternative to the use of unfixed material, particularly for morphological-immunohistochemical investigations. PMID:9248856

  7. Coccidian oöcysts as type-specimens: long-term storage in aqueous potassium dichromate solution preserves DNA.

    PubMed

    Williams, R B; Thebo, P; Marshall, R N; Marshall, J A

    2010-05-01

    Preservation of the exogenous oöcyst stage of coccidian parasites (phylum Apicomplexa N.D. Levine, 1970) as type-specimens of newly described species has long been problematical. Conventional fixatives have proved unsatisfactory, and compromises such as embedding oöcysts in resin or photographing them are not entirely appropriate for various reasons. As an alternative, chilled potassium dichromate solution (normally used in the laboratory to prevent putrefaction of temporary preparations of live oöcysts) has been tested as a long-term preservative of sporulated oöcysts of Eimeria brunetti P.P. Levine, 1942, E. maxima Tyzzer, 1929, E. mitis Tyzzer, 1929, E. necatrix Johnson, 1930, E. praecox Johnson, 1930 and E. tenella (Railliet & Lucet, 1891) (suborder Eimeriorina Léger, 1911; family Eimeriidae Minchin, 1903). Oöcysts from faeces of chickens Gallus gallus (Linnaeus) were placed in 2.5% w/v aqueous potassium dichromate solution (PDS) and stored in the dark at 4 +/- 2 degrees C. After 23 years in storage, oöcysts of each species were administered orally to chickens and failed to initiate infections, indicating that the oöcysts were dead. Nevertheless, after about 24 years, DNA was still recoverable from the oöcysts, and the original species identifications made by classic parasitological methods were confirmed by polymerase chain reaction assays. Furthermore, after almost 25 years, microscopical examination revealed that the walls and internal structures remained well preserved in 83-98% of the oöcysts of the six species investigated. Hence, PDS is potentially suitable for the long-term preservation of sporulated coccidian oöcysts as type-specimens for taxonomic purposes. The samples used in this study are now in the care of the Natural History Museum, London, UK. It is recommended that they be monitored in like manner, by suitably qualified scientists, at intervals of about 5 years to assess their state of preservation and the recoverability of DNA

  8. [Effect of potassium dichromate on histopathologic changes in testicles of white rats and results of atomic pilograms on fur].

    PubMed

    Bulikowski, W; Woźniak, F; Borzecki, Z; Radomska, K; Kaliszuk, K; Swies, Z

    1991-01-01

    Male rats were administered, for the period of 30 days, potassium dichromate (K2Cr2O7) in a dose of 2 and 5 mg/kg of body weight and magnesium chloride (Mg Cl2) in a dose of 500 mg/kg of body weight. These two substances were also administered jointly (K2C2O7-5 mg/kg and MgCl2-500 mg/kg of body weight). In the testicles of animals receiving K2Cr2O7 in a dose of 5 mg/kg of body weight in groups III and IV there were observed changes of significant degree, mainly degenerative and multifocal, which consisted in degenerative changes of various degrees and changes of necrotic epithelium cells which, in turn, consist in cell hyper- or hypochromasia of chromatolysis or pycnosis and, too, in lesions of testicle epithelium of the spermatic epithelium cells. The cells of the Leydig intraparenchymatous gland did not reveal any histopathological changes as well as changes in the increase of hyatochemical tests. The highest concentration of chrome was in the hair of the animals receiving K2Cr2O7 in a dose of 5 mg/kg of body weight. PMID:1365005

  9. Accidental potassium dichromate poisoning. Toxicokinetics of chromium by ICP-MS-CRC in biological fluids and in hair.

    PubMed

    Goullé, J P; Saussereau, E; Grosjean, J; Doche, C; Mahieu, L; Thouret, J M; Guerbet, M; Lacroix, C

    2012-04-10

    Intoxications by chromium (Cr) compounds are very life threatening and often lethal. After oral ingestion of 2 or 3g of hexavalent Cr (Cr(VI)), gastrointestinal injury, but also hepatic and renal failure, often occurs which each leads to a fatal outcome in most patients. Cellular toxicity is associated with mitochondrial and lysosomal injury by biologically Cr(VI) reactive intermediates and reactive oxygen species. After Cr(VI) has been absorbed, there is not much that can be done except to control the main complications as the treatment is only symptomatic. The biotransformation of Cr(VI) to Cr(III) reduces the toxicity because the trivalent form does not cross cellular membranes as rapidly. In fact, more than 80% of Cr(VI) is cleared in urine as Cr(III). We report the case of a 58-year-old male patient who was admitted to hospital after accidental oral ingestion of a 30 g/L potassium dichromate (the estimated amount of ingested Cr is about 3g). ICP-MS equipped with a collision/reaction cell (CRC) and validated methods were used to monitor plasma (P), red blood cells (RBCs), urine (U) and hair chromium. For urine the results were expressed per gram of creatinine. After 7 days in the intensive care unit, the patient was discharged without renal or liver failure. P, RBC and U were monitored during 49 days. During this period Cr decreased respectively from 2088 μg/L to 5 μg/L, 631 μg/L to 129 μg/L and 3512 μg/g to 10 μg/g. The half-life was much shorter in P than in RBC as the poison was more quickly cleared from the P than from the RBC, suggesting a cellular trapping of the metal. Hair was collected 2 months after the intoxication. We report a very rare case of survival after accidental Cr poisoning which has an extremely poor prognosis and usually leads to rapid death. For the first time, this toxicokinetic study highlights a sequestration of chromium in the RBC and probably in all the cells. PMID:22024652

  10. Pycnogenol prevents potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats.

    PubMed

    Parveen, Kehkashan; Khan, Mohd Rashid; Siddiqui, Waseem A

    2009-10-30

    Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. Recent evidence indicates that Pycnogenol (PYC), French maritime pine bark extract, exhibits antioxidant potential and protects against various oxidative stressors. The aim of the present study was to examine the modulating impacts of PYC on potassium dichromate K2Cr2O7-induced oxidative damage and nephrotoxicity in rats. Male Wistar rats were divided into four groups. The first group was control, the second group was control plus pre-treated with PYC (10 mg/kg, body weight; in saline; intraperitoneally; once daily for 3 weeks) as drug control and the third group was saline pre-treated plus treated with a single injection of K2Cr2O7 (15 mg/kg, body weight; in saline; intraperitoneally) as toxicant group. The fourth group was PYC pre-treated plus K2Cr2O7 injected. Forty-eight hours after K2Cr2O7-treatment, blood was drawn for estimation of renal injury markers in serum. Rats were then sacrificed, and their kidneys were dissected for biochemical and histopathological assays. K2Cr2O7-treated rats showed significant increases in markers of renal injury in serum, including blood urea nitrogen (BUN), serum creatinine (Scr), and alkaline phosphatase (ALP), which were significantly (P < 0.05) decreased by PYC pre-treatment. Moreover, prophylactic pre-treatment of rats with PYC significantly (P < 0.05) ameliorated increased thiobarbituric reactive substances (TBARS), malonaldehyde (MDA) and protein carbonyl (PC), and decreased levels of glutathione (GSH) and catalase activity in the kidney homogenate of K2Cr2O7-treated rats. These results were also supported and confirmed with histopathological findings. The study suggests that PYC is effective in preventing K2Cr2O7-induced oxidative mediated nephrotoxicity

  11. The effect of copper on iron reduction and its application to the determination of total iron content in iron and copper ores by potassium dichromate titration.

    PubMed

    Hu, Hanjun; Tang, Yang; Ying, Haisong; Wang, Minghai; Wan, Pingyu; Jin Yang, X

    2014-07-01

    The International Standard Organization (ISO) specifies two titrimetric methods for the determination of total iron content in iron ores using potassium dichromate as titrant after reduction of the iron(III) by tin(II) chloride and/or titanium(III) chloride. These two ISO methods (ISO2597-1 and ISO2597-2) require nearly boiling-point temperature for iron(III) reduction and suffer from copper interference and/or mercury pollution. In this study, potassium borohydride was used for reduction of iron(III) catalyzed by copper ions at ambient temperatures. In the absence of copper, iron(III) reduction by potassium borohydride was sluggish while a trace amount of copper significantly accelerated the reduction and reduced potassium borohydride consumption. The catalytic mechanism of iron(III) reduction in sulfuric acid and hydrochloric acid was investigated. Potassium borohydride in sodium hydroxide solution was stable without a significant degradation within 24h at ambient conditions and the use of potassium borohydride prepared in sodium hydroxide solution was safe and convenient in routine applications. The applicability of potassium borohydride reduction for the determination of total iron content by potassium dichromate titration was demonstrated by comparing with the ISO standard method using iron and copper ore reference materials and iron ore samples. PMID:24840467

  12. A novel dichromic self-referencing optical probe SrO:Bi(3+),Eu(3+) for temperature spatially and temporally imaging.

    PubMed

    Fu, Jipeng; Pang, Ran; Jiang, Lihong; Jia, Yonglei; Sun, Wenzhi; Zhang, Su; Li, Chengyu

    2016-09-14

    A novel dichromic luminescence probe SrO:Eu(3+),Bi(3+) for temperature sensing is achieved. The detailed luminescence properties, e.g., the excitation emission spectra, energy transfer efficiency, luminescence decay lifetimes and temperature dependent luminescence are comprehensively studied. The two dominant emissions (5)D0→(7)F2 transition of Eu(3+) and the (3)P1→(1)S0 transition of Bi(3+) display adjustable spectrum area. The interaction effect between Eu(3+) and Bi(3+) are proposed. The dichromic emissions are specifically responding to temperature with high sensitivity at ultra-wide range from 30 to 400 °C. Spatial and temporal temperature images on an aircraft surface have been successfully realized under excitation of commercial 365 nm light emitting diode (LED) by painting the SrO:Bi(3+),Eu(3+) phosphor on a plane model. Finally, the thermal quenching mechanism revealed by Arrhenius theory is employed to interpret the temperature sensitive luminescence behaviour. PMID:27346488

  13. Potential reproductive health effects and oxidative stress associated with exposure to potassium dichromate (K2Cr2O7) and magnesium sulphate (MgSO4) in male mice

    PubMed Central

    Rasool, Mahmood; Zaigham, Kalsoom; Malik, Arif; Naseer, Muhammad Imran; Umm-e-Habiba; Manan, Abdul; Qazi, Mahmood Husain; Asif, Muhammad

    2014-01-01

    Objective: To investigate the potential harmful effects of potassium dichromate and magnesium sulphate causing oxidative stress and reproductive toxicity in adult male mice model. Methods: The experimental work was conducted on sixty male mice (Mus musculus) divided into three groups. Mice in group B and C received potassium dichromate and magnesium sulphate of 5.0 and 500 mg/Kg body weight/ml respectively, for sixty days. The blood sample was analyzed to assess oxidative stress and cellular damage. Results: Results showed high malondialdehyde (MDA) and low levels of antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)] in both potassium dichromate and magnesium sulphate administrated groups as compared to control group. Reduced number of sperm count and excessive destruction of testicular follicles, including destruction of spermatids, leydig cells and sertoli cells, were also seen in both groups. Conclusion: We concluded from present study that potassium dichromate and magnesium sulphate causes oxidative stress by generation of reactive oxygen species (ROS) and causing DNA damage in testicular cells leading to adverse reproductive abnormalities. PMID:25097524

  14. Crystal structure of 1,4-bis­(3-ammonio­prop­yl)piperazine-1,4-diium bis­[dichromate(VI)

    PubMed Central

    Vetrivel, S.; Vinoth, E.; Mullai, R. U.; Aruljothi, R.; NizamMohideen, M.

    2016-01-01

    The asymmetric unit of the organic–inorganic title salt, (C10H28N4)[Cr2O7]2, comprises one half of an 1,4-bis­(3-ammonio­prop­yl)piperazinediium cation (the other half being generated by the application of inversion symmetry) and a dichromate anion. The piperazine ring of the cation adopts a chair conformation, and the two CrO4 tetra­hedra of the anion are in an almost eclipsed conformation. In the crystal, the cations and anions form a layered arrangement parallel to (001). N—H⋯O hydrogen bonds between the cations and anions and additional C—H⋯O inter­actions lead to the formation of a three-dimensional network structure. PMID:27308002

  15. Catalytic kinetic spectrophotometry for the determination of trace amount of oxalic acid in biological samples with oxalic acid-rhodamine B-potassium dichromate system

    NASA Astrophysics Data System (ADS)

    Zhai, Qing-Zhou; Zhang, Xiao-Xia; Liu, Qing-Zhou

    2006-09-01

    A new catalytic kinetic spectrophotometric method was proposed for determining trace oxalic acid based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamin B in 0.10 M of sulfuric acid. Good linearity is obtained over the concentration range 0.40-6.0 μg/mL of oxalic acid. After the reactions of the catalytic and non-catalytic systems were terminated by using 2.00 mL of 4 M sodium hydroxide solution, they can be stable for 3 h at room temperature. The apparent activation energy of the catalytic reaction is 12.44 kJ/mol. The effect of 50 coexisting substances was observed. The method was used to determine trace oxalic acid in tea, spinach and urine samples with satisfactory results.

  16. Curcumin Pretreatment Prevents Potassium Dichromate-Induced Hepatotoxicity, Oxidative Stress, Decreased Respiratory Complex I Activity, and Membrane Permeability Transition Pore Opening

    PubMed Central

    García-Niño, Wylly Ramsés; Tapia, Edilia; Zazueta, Cecilia; Zatarain-Barrón, Zyanya Lucía; Hernández-Pando, Rogelio; Vega-García, Claudia Cecilia; Pedraza-Chaverrí, José

    2013-01-01

    Curcumin is a polyphenol derived from turmeric with recognized antioxidant properties. Hexavalent chromium is an environmental toxic and carcinogen compound that induces oxidative stress. The objective of this study was to evaluate the potential protective effect of curcumin on the hepatic damage generated by potassium dichromate (K2Cr2O7) in rats. Animals were pretreated daily by 9-10 days with curcumin (400 mg/kg b.w.) before the injection of a single intraperitoneal of K2Cr2O7 (15 mg/kg b.w.). Groups of animals were sacrificed 24 and 48 h later. K2Cr2O7-induced damage to the liver was evident by histological alterations and increase in the liver weight and in the activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase in plasma. In addition, K2Cr2O7 induced oxidative damage in liver and isolated mitochondria, which was evident by the increase in the content of malondialdehyde and protein carbonyl and decrease in the glutathione content and in the activity of several antioxidant enzymes. Moreover, K2Cr2O7 induced decrease in mitochondrial oxygen consumption, in the activity of respiratory complex I, and permeability transition pore opening. All the above-mentioned alterations were prevented by curcumin pretreatment. The beneficial effects of curcumin against K2Cr2O7-induced liver oxidative damage were associated with prevention of mitochondrial dysfunction. PMID:23956771

  17. Dissolution kinetics of granular calcium carbonate in concentrated aqueous sodium dichromate solution at pH 6.0-7.0 and 110-130 degrees C.

    PubMed

    Wang, Tiangui; Li, Zuohu

    2005-01-01

    An understanding of the factors controlling calcite dissolution is important for modeling geochemical cycles and impacts of greenhouse gases on climate, diagenesis of sediments, and sedimentary rocks. It also has practical significance in the investigation of behavior of carbonates in petroleum and natural gas reservoirs and in the preservation of buildings and monuments constructed from limestone and marble. A large number of papers have been published on dissolution kinetics of calcium carbonate in aqueous solutions. But few involved the near-equilibrium region, especially at elevated temperatures and in concentrated solutions. In this paper, the dissolution kinetics of calcium carbonate in concentrated aqueous sodium dichromate solutions at pH 6.0-7.0 and 110-130 degrees C were studied in a 2-L autoclave. The results indicate that the dissolution reaction is mix-controlled, with surface reaction as the prevailing factor. The concentration of calcium ions in solution hardly affects the dissolution rate, but carbon dioxide in the vapor phase inhibits the dissolution reaction. The dissolution rate can be expressed by R = k(1)a(2)(H+) + k(2), and the apparent activation energy is 55-84 kJ mol(-1). PMID:15567388

  18. Elevated tissue Cr levels, increased plasma oxidative markers, and global hypomethylation of blood DNA in male Sprague-Dawley rats exposed to potassium dichromate in drinking water.

    PubMed

    Wang, Yu; Wu, Wei; Yao, Chunji; Lou, Jianlin; Chen, Riping; Jin, Lingzhi; Wu, Nanxiang; Gao, Ming; Song, Peng; Tan, Yufeng; Liu, Kecheng

    2016-09-01

    Hexavalent chromium [Cr (VI)] is prevalent in ground water in some areas, but evidence on the toxic effects of Cr (VI) via ingestion through drinking water remains insufficient. The aims of our study were to investigate the toxic effects of Cr (VI) through oral water ingestion on oxidative stress and DNA methylation. Thirty-two Sprague-Dawley rats were randomly divided into four groups, and exposed to porassium dichromate (K2 Cr2 O7 ; 0, 30, 100, and 300 mg/L) in drinking water for 4 weeks. Mean body weight gain, mean water consumption, clinical chemistry determinations, and oxidative stress levels in plasma were measured. Global DNA methylation changes and DNA methylation status at the promoter of p16 gene were also detected. After 4 weeks, mild anemic effects and increased plasma malondialdehyde (MDA) levels occurred in rats exposed to 100 mg/L or 300 mg/L of Cr (VI). Plasma glutathione peroxidase (GSH-Px) activity decreased in all exposed groups. Global DNA methylation levels were reduced in 100 mg/L and 300 mg/L exposure groups. However, DNA methylation status at the promoter of P16 gene remained unchanged in all K2 Cr2 O7- treated groups. The correlation analysis indicated that increased MDA levels were closely correlated to global DNA hypomethylation. Our results indicated that oral ingestion of Cr (VI) through drinking water caused not only oxidative stress in plasma, but also global DNA hypomethylation in blood cells from male rats, and a good correlation was found between increased MDA levels and reduced global DNA methylation. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1080-1090, 2016. PMID:25846368

  19. Using multifractal analysis of ultra-weak photon emission from germinating wheat seedlings to differentiate between two grades of intoxication with potassium dichromate

    NASA Astrophysics Data System (ADS)

    Scholkmann, Felix; Cifra, Michal; Alexandre Moraes, Thiago; de Mello Gallep, Cristiano

    2011-12-01

    The aim of the present study was to test whether the multifractal properties of ultra-weak photon emission (UPE) from germinating wheat seedlings (Triticum aestivum) change when the seedlings are treated with different concentrations of the toxin potassium dichromate (PD). To this end, UPE was measured (50 seedlings in one Petri dish, duration: approx. 16.6- 28 h) from samples of three groups: (i) control (group C, N = 9), (ii) treated with 25 ppm of PD (group G25, N = 32), and (iii) treated with 150 ppm of PD (group G150, N = 23). For the multifractal analysis, the following steps where performed: (i) each UPE time series was trimmed to a final length of 1000 min; (ii) each UPE time series was filtered, linear detrended and normalized; (iii) the multifractal spectrum (f(α)) was calculated for every UPE time series using the backward multifractal detrended moving average (MFDMA) method; (iv) each multifractal spectrum was characterized by calculating the mode (αmode) of the spectrum and the degree of multifractality (Δα) (v) for every UPE time series its mean, skewness and kurtosis were also calculated; finally (vi) all obtained parameters where analyzed to determine their ability to differentiate between the three groups. This was based on Fisher's discriminant ratio (FDR), which was calculated for each parameter combination. Additionally, a non-parametric test was used to test whether the parameter values are significantly different or not. The analysis showed that when comparing all the three groups, FDR had the highest values for the multifractal parameters (αmode, Δα). Furthermore, the differences in these parameters between the groups were statistically significant (p < 0.05). The classical parameters (mean, skewness and kurtosis) had lower FDR values than the multifractal parameters in all cases and showed no significant difference between the groups (except for the skewness between group C and G150). In conclusion, multifractal analysis enables

  20. Inferences on the nature of a Cr(V) or Cr(IV) species formed by reduction of dichromate by a bovine liver homogenate: NMR and mass-spectrometric studies.

    PubMed

    Gaggelli, Elena; D'Amelio, Nicola; Gaggelli, Nicola; Valensin, Gianni; Bovalini, Lucia; Paffetti, Alessandro; Trabalzini, Lorenza

    2003-01-01

    A low-molecular weight chromium-containing fraction of the material resulting from dichromate reduction by bovine liver homogenate was investigated by NMR and ES-MS. The ES-MS spectrum showed a readily detectable peak at m/z = 786.1. The same molecular weight reasonably agreed with the relatively low diffusion coefficient measured by NMR-DOSY experiments on the main species observed in the (1)H NMR spectrum. At least two downfield shifted and broad paramagnetic signals were apparent in the (1)H NMR spectrum. Temperature dependence of chemical shift was exploited in order to estimate the diamagnetic shift of the signals in the diamagnetic region of the spectrum. 2D TOCSY, NOESY, COSY and (1)H-(3)C HMQC spectra revealed the presence of aromatic protons (which were assigned as His residues), Gly and some other short chain amino-acids. Combinations of the molecular masses of such components together with acetate (which is present in the solution) and chromium atoms allowed a tentative proposal of a model for the compound. PMID:18365060

  1. An effective processing agent for dichromated gelatin

    NASA Astrophysics Data System (ADS)

    Pirodda, Luciano; Moriconi, Marcella

    1988-01-01

    It has been found that the proteolytic enzyme papain in diluted water solutions possesses remarkable properties as a developing agent of light exposed DCG layers, since it strongly enhances the relief character of the images. Said properties are particularly evident with not-too-high spacial frequencies and high contrast in the exposure. Some experimental applications are presented.

  2. ALCHEMI of niobium dichrome/vanadium C15 Laves phase

    SciTech Connect

    Kotula, P.G.; Chu, Fuming; Mitchell, T.E.; Anderson, I.M.; Bentley, J.

    1996-05-01

    33Nb42Cr25V was prepared by arc melting and annealing at 1400 C for 120 hr. Energy-dispersive x-ray spectra were collected over a range of {l_brace}400{l_brace} excitations between symmetry and beyond {l_brace}12 0 0{l_brace}. Results show that at least qualitatively V substitutes for Cr. Therefore, electronic effects must be more important than size effects in this case.

  3. Dichromated-gelatin hologram process for improved optical quality

    NASA Technical Reports Server (NTRS)

    Stewart, W. C.

    1975-01-01

    Optical distortions are eliminated by use of wetting agency followed by sequential immersion in several alcohol-water baths of increasing alcohol concentration. Dehydration proceeds uniformly over surface of gelatin. Dried plate is free of optically-distorting thickness variations.

  4. Hologram Scanner Design And Fabrication In Dichromated Gelatin (DCG)

    NASA Astrophysics Data System (ADS)

    Rallison, Richard; Lowe, Rick

    1983-07-01

    Two major applications of holographic scanners are considered, the first is the code reader scanner now in use in supermarkets and soon to be used in automated warehousing. The second is the multipurpose line scanner currently used in line printers and soon to be included in automated inspection systems. Code reader facets perform multiple functions, each one deflects and focuses laser light at a unique angle and scans a short arc, the return light from a bar code is collimated by the same facet and is subsequently focused through a small aperture. Ambient light is diffracted at other angles and focused at points all around the aperture giving a high signal to noise ratio and the large high efficiency facets gather sufficient return light so that photo diodes and low power lasers can be used in the system. Line scanners can be made in a large variety of sizes and configurations inexpensively and with perfect fidelity, each one being a holographic replica of a master hologram. Focused arcs as well as parallel straight lines and even arbitrary computer generated scans are possible. The limitations and considerations of such devices are discussed along with design criteria related to fabrication problems and actual production line results.

  5. Silver chromate and silver dichromate nanostructures: Sonochemical synthesis, characterization, and photocatalytic properties

    SciTech Connect

    Soofivand, Faezeh; Mohandes, Fatemeh; Salavati-Niasari, Masoud

    2013-06-01

    Graphical abstract: In this work, Ag{sub 2}CrO{sub 4} and Ag{sub 2}Cr{sub 2}O{sub 7} nanostructures have been sonochemically prepared using silver salicylate. The effect of preparation parameters on the morphology of the products was investigated by SEM images. Highlights: ► Herein, Ag{sub 2}CrO{sub 4} and Ag{sub 2}Cr{sub 2}O{sub 7} nanostructures have been sonochemically prepared. ► The effect of preparation parameters on the morphology of the products was investigated. ► The photocatalytic activity of the as-prepared Ag{sub 2}CrO{sub 4} nanoparticles was tested. ► XPS spectra indicated the high purity of Ag{sub 2}Cr{sub 2}O{sub 7} nanostructures obtained. - Abstract: In this work, Ag{sub 2}CrO{sub 4} and Ag{sub 2}Cr{sub 2}O{sub 7} nanostructures have been produced via a sonochemical method using silver salicylate as precursor. Besides silver salicylate, Na{sub 2}CrO{sub 4} and (NH{sub 4}){sub 2}Cr{sub 2}O{sub 7} as starting reagents were applied. To investigate the effect of preparation parameters on the morphology and particle size of Ag{sub 2}CrO{sub 4} and Ag{sub 2}Cr{sub 2}O{sub 7}, sonication time, type of surfactant and its concentration were changed. The as-produced nanostructures were characterized by techniques like powder X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The scanning electron micrographs showed that particle-like and rod-like nanostructures of Ag{sub 2}CrO{sub 4} and Ag{sub 2}Cr{sub 2}O{sub 7} were produced using different surfactants. To investigate the catalytic properties of Ag{sub 2}CrO{sub 4} nanoparticles, photooxidation of methyl orange (MO) was performed. According to the obtained results, it was found that the methyl orange degradation was about 87.3% after 280 min irradiation of visible light.

  6. Dichromated polyvinyl alcohol (DC-PVA) wet processed for high index modulation

    NASA Astrophysics Data System (ADS)

    Rallison, Richard D.

    1997-04-01

    PVA films have been used as mold releases, strippable coatings, binders for photopolymers and when sensitized with metals and/or dyes they have been used as photoresists, volume HOEs, multiplexed holographic optical memory and real time non destructive holographic testing. The list goes on and includes Slime and birth control. In holography, DC-PVA is a real time photoanisotropic recording material useful for phase conjugation experiments and also a stable long term storage medium needing no processing other than heat. Now we add the capability of greatly increasing the versatility of PVA by boosting the index modulation by almost two orders of magnitude. We can add broadband display and HOE applications that were not possible before. Simple two or three step liquid processing is all that is required to make the index modulation grow.

  7. 75 FR 35796 - Busan 74 (2-hydroxypropyl methanethiosulfonate); Chlorine Gas; and Dichromic Acid, et al...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-23

    ... pesticides listed in the table in Unit III.A. With this document, EPA is opening the public comment period for these registration reviews. Registration review is EPA's periodic review of pesticide... identification (ID) number for the specific pesticide of interest provided in the table in Unit III.A., by one...

  8. Crystal structure of hexa-kis-(urea-κO)chromium(III) dichromate bromide monohydrate from synchrotron X-ray data.

    PubMed

    Moon, Dohyun; Tanaka, Shinnosuke; Akitsu, Takashiro; Choi, Jong-Ha

    2015-11-01

    The title bromide salt, [Cr{CO(NH2)2}6](Cr2O7)Br·H2O, is isotypic to the corresponding chloride salt. Within the complex cation, the Cr(III) atom is coordinated by six O atoms of six urea ligands, displaying a slightly distorted octa-hedral coordination environment. The Cr-O bond lengths involving the urea ligands are in the range 1.9534 (13)-1.9776 (12) Å. The Cr2O7 (2-) anion has a nearly staggered conformation, with a bridging angle of 130.26 (10)°. The individual components are arranged in rows extending parallel to [100]. The Br(-) anion links the complex cation, as well as the solvent water mol-ecule, through N-H⋯Br and O-H⋯Br hydrogen-bonding inter-actions. The supra-molecular architecture also includes N-H⋯O and O-H⋯O hydrogen bonding between urea N-H and water O-H donor groups and the O atoms of the Cr2O7 (2-) anion as acceptor atoms, leading to a three-dimensional network structure. PMID:26594505

  9. Crystal structure of hexa­kis­(urea-κO)chromium(III) dichromate bromide monohydrate from synchrotron X-ray data

    PubMed Central

    Moon, Dohyun; Tanaka, Shinnosuke; Akitsu, Takashiro; Choi, Jong-Ha

    2015-01-01

    The title bromide salt, [Cr{CO(NH2)2}6](Cr2O7)Br·H2O, is isotypic to the corresponding chloride salt. Within the complex cation, the CrIII atom is coordinated by six O atoms of six urea ligands, displaying a slightly distorted octa­hedral coordination environment. The Cr—O bond lengths involving the urea ligands are in the range 1.9534 (13)–1.9776 (12) Å. The Cr2O7 2− anion has a nearly staggered conformation, with a bridging angle of 130.26 (10)°. The individual components are arranged in rows extending parallel to [100]. The Br− anion links the complex cation, as well as the solvent water mol­ecule, through N—H⋯Br and O—H⋯Br hydrogen-bonding inter­actions. The supra­molecular architecture also includes N—H⋯O and O—H⋯O hydrogen bonding between urea N—H and water O—H donor groups and the O atoms of the Cr2O7 2− anion as acceptor atoms, leading to a three-dimensional network structure. PMID:26594505

  10. An Ideal Detector Composed of Two-Dimensional Cd(II)-Triazole Frameworks for Nitro-Compound Explosives and Potassium Dichromate.

    PubMed

    Wang, Ying; Cheng, Lin; Liu, Zheng-Yu; Wang, Xiu-Guang; Ding, Bo; Yin, Long; Zhou, Bing-Bing; Li, Ming-Shu; Wang, Jia-Xuan; Zhao, Xiao-Jun

    2015-09-28

    The two-dimensional (2D) metal-organic framework (MOF) [Cd(TPTZ)(H2O)2(HCOOH)(IPA)2]n (1; TPTZ = {4-[4-(1H-1,2,4-triazol-1-yl)phenyl]phenyl}-1H-1,2,4-triazole, IPA = isophthalic acid) has been constructed with the π-electron-rich aromatic ligand TPTZ, auxiliary ligand IPA, and the metal Cd(2+) ion with a d(10) configuration under solvothermal conditions. Complex 1 exhibits a strong ligand-originated photoluminescence emission, which is selectively sensitive toward electron-deficient nitroaromatic compounds, such as nitrobenzene (NB), 1,3-dinitrobenzene (m-DNB), and 1,4-dinitrobenzene (p-DNB), and nitro-aliphatic compounds, such as nitromethane (NM) and tris(hydroxymethyl)nitromethane. This property makes complex 1 a potential fluorescence sensor for these chemicals. Single-crystal X-ray diffraction studies revealed that dinuclear cadmium building units were further bridged by TPTZ ligands to give a four-connected uninodal net with the Schläfli symbol of [4.6(3).4.6(3).6(2).6(4)]. PMID:26291651

  11. Effect of long-term ingestion of chromium compounds on aggression, sex behavior and fertility in adult male rat.

    PubMed

    Bataineh, H; al-Hamood, M H; Elbetieha, A; Bani Hani, I

    1997-08-01

    The effects of long-term ingestion of chromium chloride (trivalent compound) and potassium dichromate (hexavalent compound) was investigated on sexual behavior, aggressive behavior and fertility in male rats. Adult male rats were exposed to chromium chloride and potassium dichromate in drinking water at a concentration of 1000 ppm for 12 weeks. The exposure of male rats to chromium chloride and potassium dichromate reduced the number of mounts. The exposure of male rats to potassium dichromate increased the time to ejaculation. On the other hand, the exposure of male rats to chromium chloride and potassium dichromate increased the post ejaculatory interval. The number of animals ejaculating were reduced in chromium chloride and potassium dichromate exposed male rats. The exposure of male rats to chromium chloride and potassium dichromate decreased lateralizations, boxing bouts and fights with stud male. The exposure of male rats to chromium chloride and potassium dichromate had no effect on fertility. Testes, seminal vesicle and preputial gland weights were significantly reduced in chromium chloride- and potassium dichromate-exposed males. In conclusion, the long-term ingestion of chromium chloride and potassium dichromate would have adverse effects on sexual behavior and territorial aggression in adult male rat. PMID:9292274

  12. 40 CFR 415.175 - New source performance standards (NSPS).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Sodium Dichromate and Sodium Sulfate Production Subcategory § 415.175 New source performance standards (NSPS). Any new source...

  13. 40 CFR 415.172 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SOURCE CATEGORY Sodium Dichromate and Sodium Sulfate Production Subcategory § 415.172 Effluent... practicable control technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32... technology currently available (BPT): Subpart Q—Sodium Dichromate Pollutant or pollutant property...

  14. Determination of nitrogen in titanium nitride

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Tetzlaff, J. E.

    1970-01-01

    Quantitative determination of nitrogen in titanium nitride involves dissolution of TiN in 10M hydrofluoric acid containing an oxidant. Released nitrogen is determined as ammonia. Best oxidizers are ferric chloride, potassium iodate, and potassium dichromate.

  15. [Developments in chromate allergy in the German construction industry].

    PubMed

    Bock, M; Schmidt, A; Bruckner, T; Diepgen, T L

    2004-05-01

    For decades potassium dichromate has been the most important allergen in the construction industry. In Scandinavian countries the prevalence of potassium dichromate sensitization declined following the introduction of low-chromate cement. In contrast, analysis of our register in Northern Bavaria and the data of workers compensation board show no significant decline in potassium dichromate sensitization in the German construction industry during the 1990s. In 1993, German legislation provided an Approved Code of Practice and the cement manufacturers committed themselves to reduce the level of water-soluble chromates to less than 2 ppm in bag cement. Since 2000 this agreement has also included ready-mixed concrete. It remains to be seen, if sensitization against potassium dichromate will decline in the upcoming years. Based on our data, it would be desirable if only low-chromate cement was used in the construction industry in Germany as in Scandinavia. PMID:15127151

  16. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Presents three demonstrations suitable for undergraduate chemistry classes. Focuses on experiments with calcium carbide, the induction by iron of the oxidation of iodide by dichromate, and the classical iodine clock reaction. (ML)

  17. A rapid stress-corrosion test for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Helfrich, W. J.

    1968-01-01

    Stressed alloy specimens are immersed in a salt-dichromate solution at 60 degrees C. Because of the minimal general corrosion of these alloys in this solution, stress corrosion failures are detected by low-power microscopic examination.

  18. Insights: Tools of the Trade.

    ERIC Educational Resources Information Center

    Bruno, Michael J.

    1988-01-01

    Describes a demonstration showing the chemical reversibility between the chromate and dichromate ions. Includes reaction equations and listing of equipment needed. Recommends a demonstration for illustrating Le Chatelier's principle and stoichiometric relationships. (ML)

  19. 40 CFR 415.122 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32, any existing point... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.122 Effluent limitations...

  20. 40 CFR 415.122 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32, any existing point... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.122 Effluent limitations...

  1. 40 CFR 415.122 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32, any existing point... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.122 Effluent limitations...

  2. 40 CFR 415.122 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32, any existing point... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.122 Effluent limitations...

  3. 40 CFR 415.123 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any existing point source... CATEGORY Potassium Dichromate Production Subcategory § 415.123 Effluent limitations guidelines...

  4. 40 CFR 415.123 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any existing point source... CATEGORY Potassium Dichromate Production Subcategory § 415.123 Effluent limitations guidelines...

  5. 40 CFR 415.122 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... technology currently available (BPT). Except as provided in 40 CFR 125.30 through 125.32, any existing point... SOURCE CATEGORY Potassium Dichromate Production Subcategory § 415.122 Effluent limitations...

  6. 40 CFR 415.123 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any existing point source... CATEGORY Potassium Dichromate Production Subcategory § 415.123 Effluent limitations guidelines...

  7. 40 CFR 415.123 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any existing point source... CATEGORY Potassium Dichromate Production Subcategory § 415.123 Effluent limitations guidelines...

  8. 40 CFR 415.123 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any existing point source... CATEGORY Potassium Dichromate Production Subcategory § 415.123 Effluent limitations guidelines...

  9. Beware of the Permanganate Volcano.

    ERIC Educational Resources Information Center

    Snyder, Ellie

    1980-01-01

    Discusses hazards associated with the permanganate demonstration of volcanic eruptions. Alternate demonstrations are described, including the ammonium dichromate reaction, lava flow demonstration with baking soda and vinegar, and punk to illustrate air pollution from volcanic ash and cinders. (CS)

  10. Determination of Alcohol in Breath for Law Enforcement

    ERIC Educational Resources Information Center

    Treptow, Richard S.

    1974-01-01

    Describes the design and use of the dichromate-photometric breath analyzer. The discussion of this instrument provides a vehicle for demonstrating the relevance of chemical principles to everyday life. (GS)

  11. 40 CFR 415.177 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CATEGORY Sodium Dichromate and Sodium Sulfate Production Subcategory § 415.177 Effluent limitations... conventional pollutant control technology (BCT). Except as provided in 40 CFR 125.30 through 125.32,...

  12. Progress on standardization of electron beam dosimetry for radiation processing

    NASA Astrophysics Data System (ADS)

    Chenghua, Li; Yanli, Zhang; Ruicao, Pang; Zhimian, Liu; Xuan, Xia; Jingmin, Wu

    1993-10-01

    The high dose standards and dissemination system of electron beams are being established at NIM. The graphite and/ or water calorimeters and liquid chemical dosimeter are to be accepted as standards. The transfer dosimeter selected are alanine/ESR dosimeter and radiochromic film (FWT - 60). Several kinds of radiochromic films, undyed cellulose triacetate, polyethylene and blue cellophane will be recommended as working dosimeter. A series of intercomparison studies are conducted between calorimeter and dichromate dosimeter. Agreement is found within 2%. Water calorimeters and dichromate dosimeters are used to make absolute dosimetric measurements of electron beams. These calibrated beams are then used to calibrate several types of dosimeters, such as alanine, radiochromic films, undyed and dyed polyethylene. Preliminary studies show that water calorimeter and dichromate dosimeter are reproducible and sufficiently accurate for electron beam calibration. The estimated overall uncertainty of the measurement is better than 5% at 95% confidence level.

  13. Enhanced removal of soluble Cr(VI) by using zero-valent iron composite supported by surfactant-modified zeolites.

    PubMed

    Dang, Hongyu; Zhang, Yongxiang; Du, Peiwen

    2014-01-01

    Zero-valent iron (ZVI) was immobilized onto surfactant-modified zeolites (SMZ) using calcium alginate. Scanning electron microscopy showed that ZVI powder was uniformly immobilized on the surface of the SMZ. The added ZVI powder resulted in enhanced dichromate removal efficiency and the heterogeneous surface of the composite. The adsorption of dichromate onto the ZVI-SMZ composites fitted well to a pseudo-second-order model and the Langmuir adsorption isotherm. The maximum dichromate adsorption capacity of the composite was 2.49 mg/g at the temperature of 293 K. Higher removal efficiency was obtained at pH lower than 7. X-ray photoelectron spectrometry revealed that the composites combined the strong reductive quality of ZVI and superior adsorption of SMZ. PMID:25353946

  14. Grating formation in diazo salt (sensitized) gelatin.

    PubMed

    Gladden, J W

    1980-05-01

    Diazo (sensitized) gelatins are photosensitive recording materials that, unlike dichromated gelatin, have a long shelf life. Because of their stability, the diazo emulsions have replaced the dichromated colloids used in the photolithographic field and enabled commercialization of presensitized printing plates. We have produced plane wave gratings with peak efficiencies near 67% at an exposure of 625 mJ/cm(2) and a recording wavelength of 488.0 nm in one diazo recording material. Called diazo salt (sensitized) gelatin, the photosensitive material produces gratings in gelatin by a complex process that we found not to be a function of exposure. The methods used are described. PMID:20221070

  15. Effect fixation on T and B lymphocyte surface membrane antigen demonstration in paraffin processed tissue.

    PubMed

    Holgate, C S; Jackson, P; Pollard, K; Lunny, D; Bird, C C

    1986-08-01

    The identification of lymphoid surface membrane antigens in tissue sections using immunohistochemical techniques is becoming increasingly important for the diagnosis and classification of lymphoproliferative disorders. Many of the lymphocyte specific monoclonal antibodies used, however, can only be applied to frozen tissue sections. In this paper we report the successful application of a number of these antibodies to paraffin processed tissue utilizing alternative fixatives and the highly sensitive immunogold-silver staining method. The best fixatives for this purpose were formol dichromate, periodate-lysine-paraformaldehyde (PLP) and a novel fixative formed from the addition of a dichromate solution to PLP. PMID:3020216

  16. [Tefillin-related contact dermatitis].

    PubMed

    Hashkes, Philip J; Sagi, Efraim

    2011-09-01

    We describe a 14 year-old male with a background of atopic dermatitis who developed a contact dermatitis reaction on the left arm to the leather straps of tefillin (phylacteries), a religious article worn by observant Jewish men from the age 13 years during most morning prayer services. Patch testing revealed contact allergy to potassium dichromate, a chemical involved in leather tanning. Placing the leather straps over clothing and later switching to potassium dichromate-free leather straps resolved the condition. It is important to recognize this uncommon phenomena in a population in which a large proportion regularly use this religious article. PMID:22026052

  17. Photosensitive holographic material with a medium of fluorescent ink

    NASA Astrophysics Data System (ADS)

    Olivares-Pérez, A.; Toxqui-López, S.; Fuentes-Tapia, I.; Ortiz-Gutiérrez, M.; Mellado-Villaseñor, G.

    2012-03-01

    Recent researches have been reported that is possible increase the diffraction efficiency parameter from holographic gratings when photosensitive material (PVA with ammonium dichromate) it is painted after register the hologram with commercial fluorescent ink. In this research we shown that PVA as a binder, with the fluorescent ink and ammonium dichromate, this mixed can be used as recording medium. We characterize this material by implementing holographic films in which holographic gratings are recorded with a He- Cd laser at 442nm, and measuring holographic parameters such as diffraction efficiency. We get increased the diffraction efficiency and also the lifetime of the film.

  18. Electrodeposited Zinc-Nickel as an Alternative to Cadmium Plating for Aerospace Application

    NASA Technical Reports Server (NTRS)

    Mcmillan, V. C.

    1991-01-01

    Corrosion evaluation studies were conducted on 4130 alloy steel samples coated with electrodeposited zinc-nickel and samples coated with electrodeposited cadmium. The zinc nickel was deposited by the selection electrochemical metallizing process. These coated samples were exposed to a 5-percent salt fog environment at 35 plus or minus 2 C for a period ranging from 96 to 240 hours. An evaluation of the effect of dichromate coatings on the performance of each plating was conducted. The protection afforded by platings with a dichromate seal was compared to platings without the seal. During the later stages of testing, deposit adhesion and the potential for hydrogen entrapment were also evaluated.

  19. Spectroscopy on the Overhead Projector.

    ERIC Educational Resources Information Center

    Solomon, Sally; And Others

    1994-01-01

    Any overhead projector easily can be converted into a simple spectrometer by placing a piece of diffraction grating over the projecting lens. A detailed description of the apparatus and suggested spectroscopy experiments are included. Demonstrations can utilize solutions of cobalt chloride, potassium permanganate, potassium dichromate, or…

  20. A Commercial Device Involving the Breathalyzer Test Reaction.

    ERIC Educational Resources Information Center

    Dombrink, Kathleen J.

    1996-01-01

    Describes the working of Final Call, a commercially available breath analyzing device, which uses the chemical reaction involving the reduction of chromium (VI) in the orange dichromate ion to the green chromium (III) ion to detect ethyl alcohol. Presents a demonstration that simulates the use of a Final Call device. (JRH)

  1. 21 CFR 175.390 - Zinc-silicon dioxide matrix coatings.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc-silicon dioxide matrix coatings. 175.390... Coatings § 175.390 Zinc-silicon dioxide matrix coatings. Zinc-silicon dioxide matrix coatings may be safely...-base indicator. Potassium dichromate Removed by water washing. Silica gel Sodium silicate Zinc,...

  2. Safety in the Chemical Laboratory: Tested Disposal Methods for Chemical Wastes from Academic Laboratories.

    ERIC Educational Resources Information Center

    Armour, M. A.; And Others

    1985-01-01

    Describes procedures for disposing of dichromate cleaning solution, picric acid, organic azides, oxalic acid, chemical spills, and hydroperoxides in ethers and alkenes. These methods have been tested under laboratory conditions and are specific for individual chemicals rather than for groups of chemicals. (JN)

  3. OXIDATION OF MONOTETRAHYDROPYRANYLATED SHORT-CHAIN SYMMETRICAL DIOLS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The free hydroxyl functions of monotetrahydropyranylated three- to five-carbon symmetrical primary diols are oxidized to aldehydes, without cleavage of the protective group. By using a pyridinium dichromate in CH2Cl2, the oxidation procedure improved for these specific compounds. Anhydrous MgSO4 se...

  4. Troubleshooting 101: An Instrumental Analysis Experiment

    ERIC Educational Resources Information Center

    Vitt, Joseph E.

    2008-01-01

    An experiment is described where students troubleshoot a published procedure for the analysis of ethanol. UV-vis spectroscopy is used to measure the change in absorbance upon reaction of dichromate with ethanol. The experiment requires the students to critically evaluate their experimental results to correct a fundamental flaw in the original…

  5. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Cliche, Jean-Marie; And Others

    1988-01-01

    Describes two demonstrations: 1) the effect of polarity on solubility using sodium dichromate, TTE, ligroin, and water to form nonpolar-polar-nonpolar layers with the polar layer being colored; 2) determination of egg whites to be yellow by determining the content of yellow colored riboflavin in the egg white. (MVL)

  6. Computerized design and generation of space-variant holographic filters. II - Applications of space-variant filters to optical computing

    NASA Technical Reports Server (NTRS)

    Ambs, P.; Fainman, Y.; Esener, S.; Lee, S. H.

    1988-01-01

    Holographic optical elements (HOEs) of space-variant impulse response have been designed and generated using a computerized optical system. HOEs made of dichromated gelatin have been produced and used for spatial light modulator defect removal and optical interconnects. Experimental performance and characteristics are presented.

  7. Holographic Twyman-Green interferometer

    NASA Technical Reports Server (NTRS)

    Chen, C. W.; Breckinridge, J. B.

    1982-01-01

    A dichromated gelatin off-axis Fresnel zone plate was designed, fabricated, and used in a new type of interferometer for optical metrology. This single hologram optical element combines the functions of a beam splitter, beam diverger, and aberrated null lens. Data presented show the successful application for an interferometric test of an f/6, 200-mm diam parabolic mirror.

  8. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1984-01-01

    Background information and procedures are provided for a second part to the dichromate volcano demonstration. The green ash produced during the demonstration is reduced to metal using aluminothermy (Goldschmide process). Also describes suitable light sources and spectroscopes for student observation of emission spectra in lecture halls. (JN)

  9. Unnecessary Risks.

    ERIC Educational Resources Information Center

    Sievers, Dennis

    1984-01-01

    Provides safety considerations related to chemistry experiments and demonstrations. Includes procedures for a volcano demonstration (which does not use ammonium dichromate) and three clock reactions, a list of hazardous chemicals, and a list of questions to help decide whether the risk of an experiment is acceptable for a class. (JN)

  10. TOWARDS A STANDARD METHOD FOR THE MEASUREMENT OF ORGANIC CARBON IN SEDIMENTS

    EPA Science Inventory

    The precisions achieved by two different methods for analysis of organic carbon in soils and sediments were determined and compared. The first method is a rapid dichromate oxidation technique (Walkley-Black) that has long been a standard in soil chemistry. The second is an automa...

  11. Linear Dichroism of Cyanine Dyes in Stretched Polyvinyl Alcohol Films: A Physical Chemistry Laboratory Experiment.

    ERIC Educational Resources Information Center

    Natarajan, L. V.; And Others

    1983-01-01

    Provides background information, procedures, and results of an undergraduate physical chemistry experiment on the polarization of absorption spectra of cyanine dyes in stretched polyvinyl alcohol films. The experiment gives a simple demonstration of the concept of linear dichromism and the validity of the TEM method used in the analyses. (JN)

  12. 40 CFR 415.121 - Specialized definitions. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Specialized definitions. 415.121 Section 415.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Potassium Dichromate...

  13. 40 CFR 415.124 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Potassium Dichromate Production Subcategory § 415.124 Pretreatment standards for existing sources (PSES). Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve...

  14. 40 CFR 415.124 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Potassium Dichromate Production Subcategory § 415.124 Pretreatment standards for existing sources (PSES). Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve...

  15. 40 CFR 415.121 - Specialized definitions. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Specialized definitions. 415.121 Section 415.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Potassium Dichromate...

  16. 40 CFR 415.124 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Potassium Dichromate Production Subcategory § 415.124 Pretreatment standards for existing sources (PSES). Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve...

  17. 40 CFR 415.124 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Potassium Dichromate Production Subcategory § 415.124 Pretreatment standards for existing sources (PSES). Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve...

  18. 40 CFR 415.121 - Specialized definitions. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Specialized definitions. 415.121 Section 415.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Potassium Dichromate...

  19. 40 CFR 415.121 - Specialized definitions. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Specialized definitions. 415.121 Section 415.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Potassium Dichromate...

  20. 40 CFR 415.124 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Potassium Dichromate Production Subcategory § 415.124 Pretreatment standards for existing sources (PSES). Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve...

  1. METHOD FOR DETERMINING THE STABILITY OF FLUOROCARBON IOLS

    DOEpatents

    Sheldon, Z.D.; Haendler, H.M.

    1959-07-21

    A method of determining the stability of a fluorocarbon oil to uranium hexafluoride is presented. The method comprises reacting a weighed sample of the oil with condensed uranium hexafluoride in a reaction zone and titrating the amount of uranium tetrafluoride produced with potassium dichromate.

  2. 40 CFR 415.121 - Specialized definitions. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Specialized definitions. 415.121 Section 415.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Potassium Dichromate...

  3. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed... or acidification of sodium dichromate. Chromium compounds manufacturing means any process that...

  4. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed... or acidification of sodium dichromate. Chromium compounds manufacturing means any process that...

  5. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed... or acidification of sodium dichromate. Chromium compounds manufacturing means any process that...

  6. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed... or acidification of sodium dichromate. Chromium compounds manufacturing means any process that...

  7. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed... or acidification of sodium dichromate. Chromium compounds manufacturing means any process that...

  8. Preservation of Mercury in Polyethylene Containers.

    ERIC Educational Resources Information Center

    Piccolino, Samuel Paul

    1983-01-01

    Reports results of experiments favoring use of 0.5 percent nitric acid with an oxidant (potassium dichromate or potassium permanganate) to preserve samples in polyethylene containers for mercury analysis. Includes procedures used and statistical data obtained from the experiments. (JN)

  9. A Practical and Convenient Diffusion Apparatus: An Undergraduate Physical Chemistry Experiment.

    ERIC Educational Resources Information Center

    Clifford, Ben; Ochiai, E. I.

    1980-01-01

    Described is a diffusion apparatus to be used in an undergraduate physical chemistry laboratory experiment to determine the diffusion coefficients of aqueous solutions of sucrose and potassium dichromate. Included is the principle of the method, apparatus design and description, and experimental procedure. (Author/DS)

  10. 40 CFR 415.171 - Specialized definitions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Except as provided below, the general definitions, abbreviations and methods of analysis set forth in 40 CFR part 401 shall apply to this subpart. (b) The term product shall mean sodium dichromate. (c) The term Cr(T) shall mean total chromium. (d) The term Cr(+6) shall mean hexavalent chromium....

  11. Determination of metallic iron in a mixture of lime, calcium sulphide and pyrrhotite.

    PubMed

    Sastri, V S

    A method is described for the determination of metallic iron in a complex matrix consisting of calcium oxide, calcium sulphide, carbon and pyrrhotite. The procedure consists of leaching the sample with 5% ammonium chloride solution (10% sucrose solution in some cases) followed by treatment with mercury(II) chloride solution and titration with dichromate solution. PMID:18962353

  12. 40 CFR 415.174 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true 415.174 Section 415.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Sodium Dichromate and Sodium Sulfate Production Subcategory § 415.174...

  13. The corrosion protection of 6061-T6 aluminum by a polyurethane-sealed anodized coat

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1990-01-01

    The corrosion protection of 6061-T6 anodized aluminum afforded by a newly patented polyurethane seal was studied using the ac impedance technique. Values of the average corrosion rates over a 27-day exposure period in 3.5 percent NaCl solutions at pH 5.2 and pH 9.5 compared very favorably for Lockheed-prepared polyurethane-sealed and dichromate-sealed coats of the same thickness. Average corrosion rates for both specimens over the first 7 days of exposure compared well with those for a hard anodized, dichromate-sealed coat, but rose well above those for the hard anodized coat over the entire 27-day period. This is attributed both to the greater thickness of the hard anodized coat, and possibly to its inherently better corrosion protective capability.

  14. Gas Phase Spectroscopic Investigation of Chromate-Esters

    NASA Astrophysics Data System (ADS)

    Kaufman, Sydney H.; Weber, J. Mathias

    2012-06-01

    Chromate and dichromate ions are frequently used in the oxidation of alcohols. Chromate esters containing a Cr--O--C bridge are thought to be important intermediates in such reactions. We report the photofragment action spectra of two chromate ester complexes in the UV and visible regions, both of which primarily undergo cleavage of the chromate ester bond resulting in reduction of the chromate from Cr(VI) to Cr(V). Comparison to the UV/Vis absorption spectrum of a methanolic dichromate solution suggests the electronic transitions are the same ligand-to-metal charge transfer transitions in both environments. Comparing the spectral features for different fragment channels leads to insight into the energetics and fragmentation mechanism of these species.

  15. Effect of Garlic (Allium sativum) on Heavy Metal (Nickel II and ChromiumVI) Induced Alteration of Serum Lipid Profile in Male Albino Rats

    PubMed Central

    Gupta, Amrita Das; Das, Swastika N.; Dhundasi, Salim A.; Das, Kusal K.

    2008-01-01

    We have studied the effect of simultaneous oral treatment of aqueous garlic extract (Allium sativum) on heavy metal (nickel II and chromium VI) induced changes in serum lipid profile. Nickel sulfate and potassium dichromate treated rats showed a significant increase in serum low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C) and triglyceride (TG) level as well as decrease in serum high density lipoprotein-cholesterol (HDL-C) level. Simultaneous garlic administration with nickel sulfate showed improvement in serum LDL-C, HDL-C, VLDL-C and TG level. But in case of potassium dichromate, garlic administration did not show satisfactory improvement in lipid profile except VLDL-C and TG level. The results indicate that garlic (Allium sativum) has some beneficial effect in preventing heavy metal (nickel and chromium VI) induced alteration of lipid profile. PMID:19139532

  16. Contact allergy in male construction workers in Sao Paulo, Brazil, 2000-2005.

    PubMed

    Macedo, Marzia Silva; de Avelar Alchorne, Alicede Oliveira; Costa, Enilde Borges; Montesano, Fábio Tadeu

    2007-04-01

    There are no recent data on allergens in the construction industry in Brazil; apparently there were no changes in allergenic substances. The objective of this study was to identify sensitization to allergens in adult males working in the construction industry. A cross-sectional study with adult males submitted to patch tests from May 2000 to December 2005. Out of 169 male patients, 83 were construction workers. The five most frequent allergens among the construction workers were potassium dichromate (57%), carba-mix (34.9%), cobalt chloride (30.2%), thiuram-mix (27.9%) and neomycin (19.8%). There is a significant sensitization to potassium dichromate, cobalt, carba-mix, and thiuram-mix, demonstrating that cement and rubber gloves of personal protection equipment still account for allergic contact dermatitis in construction industry workers. PMID:17343626

  17. Spatial frequency behavior of holograms made with pectin and oxidizing agents

    NASA Astrophysics Data System (ADS)

    Ordóñez-Padilla, M. J.; Olivares-Pérez, A.; Grijalva-Ortiz, N.; Fuentes-Tapia, I.

    2013-03-01

    Preparation of holographic gratings using photosensitive films pectin-H2O-oxidizing agent exposed to a He-Cd laser, wavelength of 442nm. For the photo-oxidation, we used two agents: ammonium dichromate and iron ammonium citrate. Parallel studies performed experimental variation of angles between overlapping beams that generate the interference pattern, generating different spatial frequencies in the holographic gratings. Were prepared from pectin-water-ammonium dichromate and pectin-water-ammoniacal iron citrate. Results module of the transfer function (MTF) of the materials used, to determine the diffraction efficiencies as a function of the spatial frequency (line/mm) of each holographic gratings, which were prepared with different pectin and oxidizing agents. We made an experimental analysis of the MTF, comparing each of the films with different photosensitizers applied.

  18. Information profiles on potential occupational hazards: Inorganic chromium compounds. Draft report (Second)

    SciTech Connect

    Not Available

    1982-02-01

    Information profiles are presented for the following inorganic chromium compounds: chromic(VI) acid, chromic(III) hydroxide, chromic(III) oxide, chromic(III) sulfate, chromic(III) sulfate (basic), chromium dioxide, potassium dichromate(VI), lead chromate, sodium-chromate(VI), sodium-dichromate(VI), and zinc-yellow-chromate(VI). Biological effects of hexavalent chromium in humans included skin ulceration, dermatitis, nasal membrane irritation and ulceration, nasal septal perforation, rhinitis, nosebleed, nephritis, liver damage, epigastric pain, pulmonary congestion and edema, and erosion and discoloration of teeth. Chromium(VI) compounds caused mutations in a variety of systems. Exposure to trivalent chromium in the work place has caused contact dermatitis and chrome ulcers. Epidemiological studies indicated respiratory carcinogenicity among workers occupationally exposed during chromate production.

  19. Fundamental studies to develop certified reference material to calibrate spectrophotometer in the ultraviolet region

    NASA Astrophysics Data System (ADS)

    da Conceição, F. C.; Borges, P. P.; Gomes, J. F. S.

    2016-07-01

    Spectrophotometry is the technique used in a great number of laboratories around the world. Quantitative determination of a high number of inorganic, organic and biological species can be made by spectrophotometry using calibrated spectrophotometers. International standards require the use of optical filters to perform the calibration of spectrophotometers. One of the recommended materials is the crystalline potassium dichromate (K2Cr2O7), which is used to prepare solutions in specific concentrations for calibration or verification of spectrophotometers in the ultraviolet (UV) spectral regions. This paper presents the results concerning the fundamental studies for developing a certified reference material (CRM) of crystalline potassium dichromate to be used as standard of spectrophotometers in order to contribute to reliable quantitative analyses.

  20. Field screening for hexavalent chromium in soil: A fast-turnaround field method based on water extraction

    SciTech Connect

    McCain, R.G.; Baechler, M.A.

    1994-01-01

    Sodium dichromate has been identified as a contaminant of concern at several waste sites on the Hanford Site. Although chromium standards for soil are typically stated in terms of total chrome, much of the toxicity and carcinogenicity are attributed to the hexavalent state, which typically exists as a relatively mobile anion. Investigation and removal of crushed drums potentially containing residual sodium dichromate required a field test for hexavalent chromium to support characterization and remediation activities. Previous experience with a commercially available field test kit had been unsuccessful. This stimulated an effort to determine potential sources of error in the field test and led to a number of modifications that significantly improved the reliability of the test.

  1. Acute toxicity by water containing hexavalent or trivalent chromium in native Brazilian fish, Piaractus mesopotamicus: anatomopathological alterations and mortality.

    PubMed

    Castro, Marcello Pardi; de Moraes, Flávio Ruas; Fujimoto, Rodrigo Yudi; da Cruz, Claudinei; Belo, Marco Antonio de Andrade; de Moraes, Julieta Rodini Engrácia

    2014-02-01

    This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromate to yield an LC50 value at 124.2 mg L(-1). Hexavalent chromium caused reversible and irreversible lesions, which may affect organ functionality. Histopathological evaluation showed that trivalent chromium caused lesions of lower severity. Pacu subjected to different concentrations of chromium carbochelate showed no histopathological changes in the kidneys, liver, skin and gills, being similar to those of the control fish. Among the three sources of Cr(3+), only chromium chloride at 200 mg L(-1) resulted in mortality, which reached 100 % within the first 18 h. These findings confirm that trivalent chromium, when administered within recommended levels, may be used safely in aquaculture. PMID:24346495

  2. Effect of a catalyst on the kinetics of reduction of celestite (SrSO{sub 4}) by active charcoal

    SciTech Connect

    Sonawane, R.S.; Kale, B.B.; Apte, S.K.; Dongare, M.K.

    2000-02-01

    Reduction of celestite (SrSO{sub 4}) powder with particles of active charcoal has been studied extensively in the absence and presence of catalysts. The optimum temperature at the charging zone has been optimized to get a maximum water-soluble strontium sulfide value. The strontium value has been analyzed using a chemical method, which was verified by the instrumental method using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES). The conversion-time data have been analyzed by using a modified volume-reaction (MVR) model, and the effect of the catalyst on kinetic parameters has been elucidated. It was found that potassium carbonate, potassium dichromate, sodium carbonate, and sodium dichromate catalysts were found to enhance the reaction rate quite satisfactorily in the reduction of the celestite (SrSO{sub 4}).

  3. Chemical oxygen demand analysis of wastewater using trivalent manganese oxidant with chloride removal by sodium bismuthate pretreatment.

    PubMed

    Miller, D G; Brayton, S V; Boyles, W T

    2001-01-01

    Current chemical oxygen demand (COD) analyses generate wastes containing hexavalent and trivalent chromium, mercury, and silver. Waste disposal is difficult, expensive, and poses environmental hazards. A new COD test is proposed that eliminates these metals and shortens analysis time, where trivalent manganese oxidant replaces hexavalent chromium (dichromate). A silver catalyst is not required. Optional pretreatment removes chloride via oxidation to chlorine using sodium bismuthate, eliminating the need for mercury. Sample aqueous and solid components are separated for chloride removal, then recombined for total COD measurement. Soluble and nonsoluble COD can be determined separately. Digestion at 150 degrees C is complete in 1 hour. Results are determined by titration or by spectrophotometric reading. Test wastes contain none of the metals regulated for disposal under the Resource Conservation and Recovery Act. Results are shown for selected organic compounds and various wastewaters. Statistical comparisons are made with dichromate COD and biochemical oxygen demand (BOD5) test values. PMID:11558305

  4. [Determination of Total Iron and Fe2+ in Basalt].

    PubMed

    Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

    2015-08-01

    Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively. PMID:26672315

  5. Effects of toxic substances on natural bacterial assemblages determined by means of ( sup 3 H)thymidine incorporation

    SciTech Connect

    Riemann, B., Lindgaard-Jorgensen, P. )

    1990-01-01

    The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were examined by means of ({sup 3}H)thymidine incorporation into trichloroacetic acid-insoluble material. Results from a large number of coastal marine and freshwater samples suggest the following. (i) The effects of the three toxicants included reductions in the bacterial cell number as well as changes in rates of ({sup 3}H)thymidine incorporation and in ({sup 3}H)thymidine incorporation per cell. The concentrations that inhibited ({sup 3}H)thymidine incorporation by 50% ranged from 3 to 11 mg liter{sup {minus}1} for 3,5-dichlorophenol, 5 to 10 mg liter{sup {minus}1} for 2,4-dinitrophenol, and 21 to 123 mg liter{sup {minus}1} for potassium dichromate, with a tendency to higher values in bacterial assemblages from more eutrophic environments. (ii) The effects of 3,5-dichlorophenol and potassium dichromate determined by ({sup 3}H) leucine incorporation into bacterial protein were similar or larger than those obtained from ({sup 3}H) thymidine incorporation. (III) Two to four hours of exposure to the toxicants was necessary before stable maximum effects were found in ({sup 3}H)thymidine incorporation. (IV) Storage of natural environmental samples should be avoided, since tests with water stored for 1 to 3 days sometimes produced results different from results obtained from in situ tests. (V) The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were relatively constant during periods with different growth rates in the assemblages, during various periods of the year, and between samples from freshwater and marine localities.

  6. Complexation Key to a pH Locked Redox Reaction

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Dangat, Yuvraj; Shams, Tahir; Khan, Khaliquz Zaman

    2016-01-01

    An unfavorable pH can block a feasible electron transfer for a pH dependent redox reaction. In this experiment, a series of potentiometric titrations demonstrate the sequential loss in feasibility of iron(II) dichromate redox reaction over a pH range of 0-4. The pH at which this reaction failed to occur was termed as a pH locked reaction. The…

  7. Enantiomeric resolution and absolute configuration of asymmetric derivatives of 3,7-dimethylenebicyclo(3. 3. 1)nonane. Synthesis of chiral derivatives of adamantane

    SciTech Connect

    Krasutskii, P.A.; Rodionov, V.N.; Chesskaya, N.S.; Yurchenko, A.G.

    1986-01-10

    A new method was developed for the enantiomeric resolution of asymmetric derivatives of 3,7-dimethylenebicyclo(3.3.1)nonane by liquid chromatography on a chiral sorbent, i.e., silica gel impregnated with silver d-camphor-10-sulfonate. During transannular electrophilic cyclization and photocyclization the enantiomeric dienes, the absolute configurations of which were determined by means of the circular dichromism spectra, form chiral derivatives of adamantane with full retention of the optical purity.

  8. Semi-automatic version of the potentiometric titration method for characterization of uranium compounds.

    PubMed

    Cristiano, Bárbara F G; Delgado, José Ubiratan; da Silva, José Wanderley S; de Barros, Pedro D; de Araújo, Radier M S; Dias, Fábio C; Lopes, Ricardo T

    2012-09-01

    The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. PMID:22406220

  9. Reducing the drying shrinkage of cement paste by admixture surface treatments

    SciTech Connect

    Xu, Y.; Chung, D.D.L.

    2000-02-01

    The drying shrinkage of concrete during curing is a source of residual stress and cracks. The problem is particularly severe for a large structure, such as a large concrete floor. Surface treatment of carbon fibers and/or silica fume by silane prior to using these admixtures in cement paste increases the effectiveness of these admixtures for reducing the drying shrinkage. Silane treatment of fibers is more effective than dichromate treatment or ozone treatment.

  10. METHOD OF MAINTAINING PLUTONIUM IN A HIGHER STATE OF OXIDATION DURING PROCESSING

    DOEpatents

    Thompson, S.G.; Miller, D.R.

    1959-06-30

    This patent deals with the oxidation of tetravalent plutonium contained in an aqueous acid solution together with fission products to the hexavalent state, prior to selective fission product precipitation, by adding to the solution bismuthate or ceric ions as the oxidant and a water-soluble dichromate as a holding oxidant. Both oxidant and holding oxidant are preferably added in greater than stoichiometric quantities with regard to the plutonium present.

  11. Improvements of a spatial frequency analyzer for automated characterization of holographic recording materials.

    PubMed

    Couture, J J; Tanguay, D

    1992-05-10

    A spatial frequency analyzer was designed to simplify characterization studies for new holographic recording materials. Mechanical movements were automated and a complete informational system gave rapid characterization results. A good fringe stabilization unit was improved by adding simple holographic optical beam combiners. Experimental characterization of two different recording materials shows the versatility of this automated apparatus. Also we present modulation-transfer-function curves of dichromated gelatin between 500 and 3500 cycles/mm obtained with polarization volume transmission holograms. PMID:20725176

  12. Ion-exchange chromatographic separation of anions on hydrated bismuth oxide impregnated papers

    SciTech Connect

    Dabral, S.K.; Muktawat, K.P.S.; Rawat, J.P.

    1988-04-01

    A comparative study of the chromatographic behavior of anions, iodide, sulfide, phosphate, arsenate, arsenite, vanadate, chromate, dichromate, thiosulfate, thiocyanate, ferricyanide and ferrocyanide on papers impregnated with hydrated bismuth oxide and untreated Whatman no.1 paper has been made by employing identical aqueous, non-aqueous and mixed solvent system. Sharp and compact spots were obtained with impregnated papers whereas the opposite applied to plain papers. Various analytically important binary and ternary separations are reported.

  13. Relief hologram replication using a dental composite as an embossing tool

    NASA Astrophysics Data System (ADS)

    Savić Šević, Svetlana; Pantelić, Dejan

    2005-04-01

    A simplified method for holographic embossing tool production is presented. Surface relief diffraction gratings are holographically recorded in pullulan sensitized with ammonium dichromate (DCP). The surface structure is copied into dental photopolymer composite by direct contact and subsequent photo-polymerization. It was found that arbitrary surface micropattern can be replicated. Due to its excellent mechanical and thermal properties, micro-patterned dental composite can be further used as an embossing tool for mass production of holograms.

  14. Holographic recording materials - A review

    NASA Technical Reports Server (NTRS)

    Kurtz, R. L.; Owen, R. B.

    1975-01-01

    Holographic recording materials in current use are examined along with a few of their applications. Some experimental media are also studied. No effort is made to rank the commercial materials, since satisfactory results can be obtained with any of them. The discussion covers silver halide plates and films, photoresists, thermoplastics, photopolymers, dichromated gelatin, photochromic materials, electrooptical crystals, styryl free radical film, and TEP film. A convenient summation of some material properties is presented in tabular form.

  15. Optical matrix-matrix multiplication method demonstrated by the use of a multifocus hololens

    NASA Technical Reports Server (NTRS)

    Liu, H. K.; Liang, Y.-Z.

    1984-01-01

    A method of optical matrix-matrix multiplication is presented. The feasibility of the method is also experimentally demonstrated by the use of a dichromated-gelatin multifocus holographic lens (hololens). With the specific values of matrices chosen, the average percentage error between the theoretical and experimental data of the elements of the output matrix of the multiplication of some specific pairs of 3 x 3 matrices is 0.4 percent, which corresponds to an 8-bit accuracy.

  16. International Conference on Holography Applications, Beijing, People's Republic of China, July 2-4, 1986, Proceedings

    NASA Astrophysics Data System (ADS)

    Ke, Jingtang; Pryputniewicz, Ryszard J.

    Papers are presented on applications of holographic cinematography, application of the holographic technique to supersonic cascade wind tunnels, application of a holographic lens in an HUD, and a numerical method for holographic optical fiber diagnostics. Other topics include the holographic testing of a gear tooth surface, holography in biomedical science, electronic speckle pattern interferometry, a dichromated gelatin holographic scanner, and holographic aquaculture. Also considered are coherent optics in environmental monitoring, optical tomography, and optical sine transformation.

  17. Practical wet oxidation experiment to determine concentrations of particulate organic matter in seawater

    NASA Astrophysics Data System (ADS)

    Berger, V. Ya.; Mityaev, M. V.; Sukhotin, A. A.

    2016-03-01

    The report presents results of experiments testifying to the possibility of using wet oxidation to determine the concentrations of organic carbon in marine particulate matter. We describe a method for eliminating the measurement error caused by the influence of chlorides on the processes of dichromate oxidation of organic matter. We present an equation to calculate the concentration of organic carbon depending on that of sodium chloride.

  18. [Morphological features of the organs of the immune system in conditions of exposure to chromium and benzene].

    PubMed

    Ermolina, E V; Stadnikov, A A; Smoliagin, A I

    2012-01-01

    Morphological features of the thymus, spleen and lymph nodes on the 45th--and 90th day of oral exposure to benzene, potassium dichromate and their mixtures were studied in 40 Wistar rats. A strong trend to a decrease in the activity of T lymphocytes has been established. Apoptotic thymocytes and lymphocytes in the T-dependent areas of spleen and lymph nodes have been revealed. PMID:23088136

  19. Evolution of diffraction efficiency from holograms with monosaccharides

    NASA Astrophysics Data System (ADS)

    Mejias-Brizuela, N. Y.; Olivares Pérez, A.; Grande Grande, A.

    2010-02-01

    We present the behaviors in the time of the diffraction efficiency of holographic gratings, there were recorded in two monosaccharides, glucose and fructose, and both were sensitized with potassium dichromate and blue dye. There monosaccharides present diffraction efficiency with a maximum of 7% approximately, without protection, the sample exposure at environmental conditions, after 48 hours the parameter of diffraction efficiency decays. By this reason is necessary to protect after of the stabilized emulsion the hologram.

  20. Study of Melanin Bleaching After Immunohistochemistry of Melanin-containing Tissues

    PubMed Central

    Wu, Wenqiao

    2015-01-01

    Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3′-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes. PMID:24710084

  1. A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand

    PubMed Central

    Yao, Na; Liu, Zhuan; Chen, Ying; Zhou, Yikai; Xie, Bin

    2015-01-01

    A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5–7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5–1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method. PMID:26295397

  2. Frequency of standard and occupational contact allergens in Tuzla area, Bosnia and Herzegovina: retrospective study.

    PubMed

    Sijercić, Nerma; Hadzigrahić, Nermina; Kamberović, Selma; Suljagić, Edin

    2003-01-01

    Allergic contact dermatitis is acute or chronic inflammatory skin disease of allergic etiology, which develops as a result of delayed type of hypersensitivity, i.e. type IV reaction according to the Gell and Coombs classification. In the retrospective study, we reviewed medical records of 495 patients diagnosed with allergic contact dermatitis in the 1988-1998 period. The records were obtained from the Cabinet of Allergology of the Department of Dermatology and Venerology, Tuzla University Hospital Center. There were 312 women and 183 men, aged between 18 and 60 years. The patients were divided into 6 groups according to their occupation. Contact sensitization was established in 295 or 59.6% of them. The type and frequency of causative agent in allergic contact dermatitis depended on working environment. Potassium dichromate, a component part of cement, caused positive reaction in 48% of construction workers tested, which was significantly more than in the "other occupation" group, where 14.6% of patients showed positive reaction to potassium dichromate (p<0.001). Formaldehyde, used in leather processing, was the most frequent among the four leading allergens in the group of shoe workers (13.3%), whereas charcoal tar (used in the metal processing) was the most frequent allergen in the group of metal workers (13.9%). Nickel sulfate, potassium dichromate, cobalt chloride, and urushiol were frequent allergens in the "other occupation" group, housewives, and textile workers. The listed allergens are present at large in everyday life as well as in particular occupations. PMID:12773263

  3. Introduction of double amidoxime group by double post surface modification on poly(vinylbenzyl chloride) beads for higher amounts of organic dyes, As (V) and Cr (VI) removal.

    PubMed

    Ajmal, Muhammad; Demirci, Sahin; Uzun, Yusuf; Siddiq, Mohammad; Aktas, Nahit; Sahiner, Nurettin

    2016-05-15

    In this study, the synthesis of micron-sized poly(vinylbenzyl chloride) (p(VBC)) beads and subsequent conversion of the reactive chloromethyl groups to double amidoxime group containing moieties by post modification is reported. The prepared beads were characterized by SEM and FT-IR spectroscopy. The amidoximated p(VBC) beads were used as adsorbent for the removal of organic dyes, such as eosin y (EY) and methyl orange (MO), and heavy metals containing complex ions such as dichromate (Cr2O7(2-)) and arsenate (HAsO4(2)(-)) from aqueous media. The effect of the adsorbent dose on the percent removal, the effect of initial concentration of adsorbates on the adsorption rate and their amounts were also investigated. The Langmuir, Freundlich and Temkin adsorption isotherms were applied to the adsorption processes. The results indicated that the adsorption of both dichromate and arsenate ions obeyed the Langmuir adsorption model. Interestingly, it was found that the prepared beads were capable of removing significant amounts of arsenate and dichromate ions from tap and river (Sarıcay, Canakkale-Turkey) water. PMID:26930538

  4. Study for Corrosion and Hydrogen Evolution Behavior of Ti-6Al-4V Alloy in Simulated Acid Rain Water

    NASA Astrophysics Data System (ADS)

    Tammam, R. H.; Fekry, A. M.

    2014-03-01

    The electrochemical behavior of Ti-6Al-4V alloy was investigated using electrochemical impedance spectroscopy (EIS) measurements at the open circuit potentials and potentiodynamic polarization measurements in a simulated acid rain containing inorganic additives. The ac circuit model for Ti-6Al-4V alloy at corrosion interface in simulated acid rain containing inorganic additives was proposed, which was based on two time constants equivalent circuit. Ti-6Al-4V alloy in a simulated acid rain of pH 1.5 containing inorganic additives showed a characteristic of a capacitive behavior. The effect of different concentrations of the inorganic additives (iodate, dichromate, phosphate, and nitrate) on the corrosion of the alloy in acid rain water (ARW) was also studied. It was found that the corrosion rate decreases drastically in the solution containing iodate, dichromate, and phosphate anions; however, nitrate anions increase the corrosion rate of the alloy. The investigated inorganic additives had inhibiting effect on the corrosion of the alloy in ARW, and their efficiency decreases according to the order: iodate > dichromate > phosphate > blank > nitrate. Polarization data results are in good agreement with EIS.

  5. Cr (VI) induced oxidative stress and toxicity in cultured cerebellar granule neurons at different stages of development and protective effect of Rosmarinic acid.

    PubMed

    Dashti, Abolfazl; Soodi, Maliheh; Amani, Nahid

    2016-03-01

    Chromium (Cr) is a widespread metal ion in the workplace, industrial effluent, and water. The toxicity of chromium (VI) on various organs including the liver, kidneys, and lung were studied, but little is known about neurotoxicity. In this study, neurotoxic effects of Cr (VI) have been investigated by cultured cerebellar granule neurons (CGNs). Immature and mature neurons were exposed to different concentrations of potassium dichromate for 24 h and cytotoxicity was measured by MTT assay. In addition, immature neurons were exposed for 5 days as regards cytotoxic effect in development stages. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and the protective effect of Rosmarinic acid on mature and immature neurons exposed to potassium dichromate, were measured. Furthermore, lipid peroxidation, glutathione peroxidase (GPx), and acetylcholinesterase activity in mature neurons were assessed following exposure to potassium dichromate. The results indicate that toxicity of Cr (VI) dependent on maturation steps. Cr (VI) was less toxic for immature neurons. Also, Cr (VI) induced MMP reduction and ROS production in both immature and mature neurons. In Cr (VI) treated neurons, increased lipid peroxidation and GPx activity but not acetylcholinesterase activity was observed. Interestingly, Rosmarinic acid, as a natural antioxidant, could protect mature but not immature neurons against Cr (VI) induced toxicity. Our findings revealed vulnerability of mature neurons to Cr (VI) induced toxicity and oxidative stress. PMID:25213303

  6. Contact sensitivity to standard series allergens in 1038 patients with contact dermatitis in Turkey.

    PubMed

    Akyol, Aynur; Boyvat, Ayşe; Peksari, Yavuz; Gürgey, Erbak

    2005-06-01

    We planned to determine the frequency of sensitivity to European standard patch test allergens in 1038 patients with contact dermatitis. From 1992 to 2004, 1038 patients with the diagnosis of contact dermatitis were patch tested with the European standard series. Seven hundred and five patients were female (67.9%) and 333 patients were male (32.1%). A total of 336 patients (32.3%) had one or more positive patch test reactions. The most common allergens were nickel (17.6%), cobalt chloride (5.3%), potassium dichromate (4.6%), neomycin (2.4%), fragrance mix (2.1%) and balsam of Peru (2.1%). Contact sensitivity to potassium dichromate and thiuram was significantly more frequent in male patients, whereas nickel and primin sensitivity was significantly more frequent in female patients. Higher sensitivity rates for potassium dichromate, neomycin, balsam of Peru, wool alcohol, fragrance mix and primin were noted in patients over 40 years of age. Sensitivity rates of the standard series allergens were all similar in atopic patients and in non-atopic patients. Metals, neomycin and fragrances are the leading allergens in Turkey. Although fragrances are among the most important sensitizers, sensitivity rates to fragrances and also to preservatives are much lower than the rates in Europe and the US. PMID:15932585

  7. Study of melanin bleaching after immunohistochemistry of melanin-containing tissues.

    PubMed

    Shen, Hongwu; Wu, Wenqiao

    2015-04-01

    Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3'-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes. PMID:24710084

  8. Enhanced Exopolymer Production and Chromium Stabilization in Pseudomonas putida Unsaturated Biofilms

    PubMed Central

    Priester, John H.; Olson, Scott G.; Webb, Samuel M.; Neu, Mary P.; Hersman, Larry E.; Holden, Patricia A.

    2006-01-01

    Chromium-contaminated soils threaten surface and groundwater quality at many industrial sites. In vadose zones, indigenous bacteria can reduce Cr(VI) to Cr(III), but the subsequent fate of Cr(III) and the roles of bacterial biofilms are relatively unknown. To investigate, we cultured Pseudomonas putida, a model organism for vadose zone bioremediation, as unsaturated biofilms on membranes overlaying iron-deficient solid media either containing molecular dichromate from potassium dichromate (Cr-only treatment) or with deposits of solid, dichromate-coated hematite (Fe+Cr treatment) to simulate vadose zone conditions. Controls included iron-deficient solid medium and an Fe-only treatment using solid hematite deposits. Under iron-deficient conditions, chromium exposure resulted in lower cell yield and lower amounts of cellular protein and carbohydrate, but providing iron in the form of hematite overcame these toxic effects of Cr. For the Cr and Fe+Cr treatments, Cr(VI) was completely reduced to Cr(III) that accumulated on biofilm cells and extracellular polymeric substances (EPSs). Chromium exposure resulted in elevated extracellular carbohydrates, protein, DNA, and EPS sugars that were relatively enriched in N-acetyl-glucosamine, rhamnose, glucose, and mannose. The proportions of EPS protein and carbohydrate relative to intracellular pools suggested Cr toxicity-mediated cell lysis as the origin. However, DNA accumulated extracellularly in amounts far greater than expected from cell lysis, and Cr was liberated when extracted EPS was treated with DNase. These results demonstrate that Cr accumulation in unsaturated biofilms occurs with enzymatic reduction of Cr(VI), cellular lysis, cellular association, and extracellular DNA binding of Cr(III), which altogether can facilitate localized biotic stabilization of Cr in contaminated vadose zones. PMID:16517647

  9. Artificial infection of chickens with Capillaria obsignata eggs embryonated in different media.

    PubMed

    Tiersch, K M; Daş, G; von Samson-Himmelstjerna, G; Gauly, M

    2014-02-24

    The present study investigated whether incubation media have an impact on infectivity of Capillaria obsignata eggs in chickens infected with gradually increasing doses. C. obsignata eggs collected from female worms were incubated either in formalin (0.5% or 2%) or in potassium dichromate 0.1% or in sulfuric acid 0.1N for three weeks (wk). One-day-old male chicks (N=92) were reared in a parasite-free environment, and infected with 0, 500, 1000 or 2000 eggs at an age of 3 wk. Post-mortem parasitological examinations were performed on day 28 p.i. Although all the infected birds harboured adult worms, their growth performance was not affected. Furthermore there was no significant interaction effect between incubation media and infection dose on worm establishment rates (P=0.080), while main effects of these two factors were significant (P<0.05). The average number of adult worms found in birds infected with the eggs incubated in potassium dichromate were significantly lower (P<0.001) than in formalin 0.5%, formalin 2% and sulfuric acid 0.1N. A higher (P<0.05) percentage of larvae could establish themselves in the intestines when the birds were infected with 500 eggs (40.5%) instead of 2000 eggs (26.2%), indicating density dependent effects. It is concluded that formalin (particularly 0.5%), and sulfuric acid can successfully be used as incubation media for C. obsignata eggs, whereas potassium dichromate impairs subsequent infectivity of the eggs. Although effects of media on the infectivity of the eggs were confirmed to be fairly repeatable, no harmful effect of infection was quantified on the host animal performance with the infection doses up to 2000 eggs. PMID:24365242

  10. Analysis of organic sulfur and nitrogen in coal via tandem degradation methods. Final technical report, September 1, 1992--August 31, 1993

    SciTech Connect

    Kruge, M.A.; Palmer, S.R.

    1993-12-31

    The principal impediment to the molecular characterization of organic sulfur and nitrogen in coal is the polymeric nature of coal`s molecular structure, rendering coal insoluble and impossible to analyze by the necessary gas chromatographic (GC) methods. In this research, the authors apply chemical and thermal degradation techniques to render coal amenable to standard GC characterization. IBC101 floated coal was oxidized with sodium dichromate in five sequential steps. The SIC ratio in the residues decreases markedly with each successive step. It appears the method is effectively mobilizing the organic sulfur. The NIC ratio shows little change. In the GC/MS analysis of the dichromate oxidation products, alkylmethoxy-thiophene carboxylic acids (ATCA) were found to be major organosulfur compounds. Their relative concentrations also drop markedly with each oxidation step, while the concentration of benzene derivatives progressively increases. It is hypothesized the thiophenic moieties are located on the exterior surfaces of the coal structure, while the core is more aromatic. Using analytical micropyrolysis-gas chromatography with a sulfur-selective flame photometric detector (py-GC-FPD), it is possible to easily see a full distribution of organic sulfur forms in a one-step analysis. The predominance of alkylthiophenes in the pyrolyzates lends support to the recognition of thiophenic compounds in the dichromate oxidation products. The thiophene concentrations in pyrolyzates are directly proportional to bulk organic sulfur values. However, thiophene distributions in Illinois Basin coals are remarkably similar, regardless of organic sulfur content. It is possible to distinguish Illinois Basin coals from foreign coals on the basis of thiophene distributions. The py-GC method has an advantage over oxidative degradation techniques in that it permits direct, one-step micro-scale analysis, requiring only a minimum of sample preparation.

  11. Evaluation on the use of cerium in the NBL Titrimetric Method

    SciTech Connect

    Zebrowski, J.P.; Orlowicz, G.J.; Johnson, K.D.; Smith, M.M.; Soriano, M.D.

    1995-03-01

    An alternative to potassium dichromate as titrant in the New Brunswick Laboratory Titrimetric Method for uranium analysis was sought since chromium in the waste makes disposal difficult. Substitution of a ceric-based titrant was statistically evaluated. Analysis of the data indicated statistically equivalent precisions for the two methods, but a significant overall bias of +0.035% for the ceric titrant procedure. The cause of the bias was investigated, alterations to the procedure were made, and a second statistical study was performed. This second study revealed no statistically significant bias, nor any analyst-to-analyst variation in the ceric titration procedure. A statistically significant day-to-day variation was detected, but this was physically small (0.01 5%) and was only detected because of the within-day precision of the method. The added mean and standard deviation of the %RD for a single measurement was found to be 0.031%. A comparison with quality control blind dichromate titration data again indicated similar overall precision. Effects of ten elements on the ceric titration`s performance was determined. Co, Ti, Cu, Ni, Na, Mg, Gd, Zn, Cd, and Cr in previous work at NBL these impurities did not interfere with the potassium dichromate titrant. This study indicated similar results for the ceric titrant, with the exception of Ti. All the elements (excluding Ti and Cr), caused no statistically significant bias in uranium measurements at levels of 10 mg impurity per 20-40 mg uranium. The presence of Ti was found to cause a bias of {minus}0.05%; this is attributed to the presence of sulfate ions, resulting in precipitation of titanium sulfate and occlusion of uranium. A negative bias of 0.012% was also statistically observed in the samples containing chromium impurities.

  12. Applications of holography; Proceedings of the Meeting, Los Angeles, CA, January 21-23, 1985

    SciTech Connect

    Huff, L.

    1985-01-01

    Among the topics discussed are: holographic displays; industrial applications of holography; dual thermoplastic holography recording; holographic interferometry applied to symmetric aerodynamic models in a wind tunnel; and fringe carrier techniques for unambiguous detection of holographically recorded displacements. Attention is also given to: holographic fringe linearization interferometry (FLI) for defect detection; tunable holographic filtering in dichromated gelatin operating in the near infrared region; holographic honeycomb microlenses; and electron-beam fabrication of computer generated holograms (CGH). Among additional topics discussed are: hologram recording with a photopolymer system; white-light Fourier holography; and white light holograms for credit card applications.

  13. Semi-automated potentiometric titration method for uranium characterization.

    PubMed

    Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

    2012-07-01

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. PMID:22154105

  14. Experimental cryptosporidiosis in laboratory mice.

    PubMed Central

    Sherwood, D; Angus, K W; Snodgrass, D R; Tzipori, S

    1982-01-01

    Eight strains of laboratory mice were susceptible to subclinical infections with Cryptosporidium sp. at 1 to 4 days of age, but only a transient infection could be established at 21 days of age or older. Immunosuppression of 21-day-old mice failed to render them more susceptible to infection. Laboratory storage conditions for Cryptosporidium sp. were investigated by titration in 1- to 4-day-old mice. Storage by freezing with a variety of cryoprotectants was unsuccessful, but storage at 4 degrees C in phosphate-buffered saline or 2.5% potassium dichromate was possible for 4 to 6 months. PMID:7141705

  15. Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating.

    SciTech Connect

    Ashley, Carol S.; Rambo, Patrick K.; Schwarz, Jens; Dunphy, Darren Robert; Branson, Eric D.; Smith, Ian Craig; Johnson, William Arthur; Reed, Scott T.; Cook, Adam W.

    2005-03-01

    In order to develop the next generation of high peak intensity lasers, new grating technology providing higher damage thresholds and large apertures is required. The current assumption is that this technical innovation will be multilayer dielectric gratings, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating. A variant of this is explored with the upper grating layer being a lower density gelatin-based volume phase grating in either sol-gel or dichromated gelatin. One key benefit is the elimination of the etching step.

  16. OXIDATIVE METHOD OF SEPARATING PLUTONIUM FROM NEPTUNIUM

    DOEpatents

    Beaufait, L.J. Jr.

    1958-06-10

    A method is described of separating neptunium from plutonium in an aqueous solution containing neptunium and plutonium in valence states not greater than +4. This may be accomplished by contacting the solution with dichromate ions, thus oxidizing the neptunium to a valence state greater than +4 without oxidizing any substantial amount of plutonium, and then forming a carrier precipitate which carries the plutonium from solution, leaving the neptunium behind. A preferred embodiment of this invention covers the use of lanthanum fluoride as the carrier precipitate.

  17. Real-time holographic gratings modulate with voltage by different thickness film

    NASA Astrophysics Data System (ADS)

    Fontanilla-Urdaneta, Rosangela C.; Olivares-Pérez, Arturo; Fuentes-Tapia, Israel

    2011-04-01

    The holographic gratings on photopolymer films are studied by three different thicknesses for samples A, B, and C. The photopolymer emulsion is prepared with potassium dichromate and nickel (II) chloride hexahydrate in polyvinyl alcohol matrix. The evolution of diffraction efficiency is evaluated during holographic recording with and without voltage as a function of energy exposure by changing the thickness. The curves of diffraction efficiency reach a peak when the films are continuously exposed to energy for a period of time. Sample B obtains the highest diffraction efficiency

  18. Holographic characterization of DYE-PVA films studied at 442 nm for optical elements fabrication

    NASA Astrophysics Data System (ADS)

    Couture, Jean J.

    1991-12-01

    The present work is an experimental study of the speed of hologram recording in dichromated polyvinyl alcohol films (DC-PVA) and DYE-DC-PVA films. Real-time recordings give high diffraction efficiency and low signal-to-noise ratio holograms without any chemical development. The dyes studied here are MALACHITE GREEN, EOSIN Y, and ROSE BENGAL introduced in DC-PVA films having a thickness of 60 - 62 micrometers . The best of these DYE-DC-PVA systems is a good candidate for holographic optical elements fabrication.

  19. Computer-originated polarizing holographic optical element recorded in photopolymerizable layers.

    PubMed

    Carré, C; Habraken, S; Roose, S

    1993-05-01

    The photosensitive system that is used in most cases to produce holographic optical holograms is dichromated gelatin. Other materials may be used, in particular, photopolymerizable layers. In the present investigation, we set out to use the polymer developed in the Laboratoire de Photochimie Générale in Mulhouse in order to duplicate a computer-generated hologram. Our technique is intended to generate polarizing properties. We took into account the fact that no wet chemistry processing is required; grating fringe spacings are not distorted through chemical development. PMID:19802257

  20. METHOD OF RECOVERING PLUTONIUM VALUES FROM AQUEOUS SOLUTIONS BY CARRIER PRECIPITATION

    DOEpatents

    James, R.A.; Thompson, S.G.

    1959-11-01

    A process is presented for pretreating aqueous nitric acid- plutonium solutions containing a small quantity of hydrazine that has formed as a decomposition product during the dissolution of neutron-bombarded uranium in nitric acid and that impairs the precipitation of plutonium on bismuth phosphate. The solution is digested with alkali metal dichromate or potassium permanganate at between 75 and 100 deg C; sulfuric acid at approximately 75 deg C and sodium nitrate, oxaiic acid plus manganous nitrate, or hydroxylamine are added to the solution to secure the plutonium in the tetravalent state and make it suitable for precipitation on BiPO/sub 4/.

  1. Synthesis and cytotoxic activity of N-substituted thiosemicarbazones of 3-(3,4-methylenedioxy)phenylpropanal.

    PubMed

    Joselice e Silva, M; Alves, A J; Do Nascimento, S C

    1998-03-01

    Five new N-substituted thiosemicarbazones of 3-(3,4-methylenedioxy)phenylpropanal were synthesized. Safrole, a natural product obtained from sassafras oil (Ocotea pretiosa), was oxidized to alcohol using BH3-THF and H2O2, followed by oxidation to aldehyde using pyridinium dichromate (PDC) and condensation with five N-substituted derivatives of thiosemicarbazide. Tests were performed to evaluate the cytotoxic activity with continuous chain KB cells (epidermoide carcinoma of the floor of the mouth). Compounds 5 and 6 showed IC50 values of 1.5 and 4.6 micrograms/ml, respectively. PMID:9639871

  2. Progress in holographic applications; Proceedings of the Meeting, Cannes, France, December 5, 6, 1985

    NASA Technical Reports Server (NTRS)

    Ebbeni, Jean (Editor)

    1986-01-01

    Papers are presented on a holographic recording material containing poly-n-vinylcarbozole, photoelectrochemical etching of holographic gratings in semiconductors, the analysis and construction of powered reflection holographic optical elements, achromatic display holograms in dichromated gelatin, and image blurring in display holograms and in holographic optical elements. Topics discussed include two-dimensional optical beam switching techniques using dynamnic holography, a new holographic interferometer with monomode fibers for integrated optics applications, computer controlled holography, and the copying of holograms using incoherent light. Consideration is given to holography of very far objects, rainbow holography with a multimode laser source, and the use of an endoscope for optical fiber holography.

  3. Real-time optical holographic tracking of multiple objects

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Liu, Hua-Kuang

    1989-01-01

    A coherent optical correlation technique for real-time simultaneous tracking of several different objects making independent movements is described, and experimental results are presented. An evaluation of this system compared with digital computing systems is made. The real-time processing capability is obtained through the use of a liquid crystal television spatial light modulator and a dichromated gelatin multifocus hololens. A coded reference beam is utilized in the separation of the output correlation plane associated with each input target so that independent tracking can be achieved.

  4. Materials for VPHGs: practical considerations in the case of astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Bianco, Andrea; Pariani, Giorgio; Zanutta, Alessio; Bertarelli, Chiara

    2012-09-01

    Volume Phase Holographic Gratings are interesting dispersing elements for astronomical instrumentation. An important point, in the realization of the grating, is the choice of the holographic material. Dichromated Gelatines (DCGs) are the best candidate, but they show some drawback especially regarding their water sensitivity and the complex developing process required to enhance their performances. New holographic materials are becoming interesting, such as photopolymers and photochromic materials. An exhaustive review of these classes of materials will be reported and their performances compared to those of DCGs, focusing mainly to the astronomical instrumentation field.

  5. PLUTONIUM SEPARATION METHOD

    DOEpatents

    Beaufait, L.J. Jr.; Stevenson, F.R.; Rollefson, G.K.

    1958-11-18

    The recovery of plutonium ions from neutron irradiated uranium can be accomplished by bufferlng an aqueous solutlon of the irradiated materials containing tetravalent plutonium to a pH of 4 to 7, adding sufficient acetate to the solution to complex the uranyl present, adding ferric nitrate to form a colloid of ferric hydroxide, plutonlum, and associated fission products, removing and dissolving the colloid in aqueous nitric acid, oxldizlng the plutonium to the hexavalent state by adding permanganate or dichromate, treating the resultant solution with ferric nitrate to form a colloid of ferric hydroxide and associated fission products, and separating the colloid from the plutonlum left in solution.

  6. METHOD OF CONTROLLING CORROSION IN A NEUTRONIC REACTOR

    DOEpatents

    Kidder, C.P.; Sloan, C.K.

    1959-10-01

    A method is described for reducing or removing corrosion and iron deposits on aluminum surfaces from coolant water comprising adding to the coolant alkali metal dichromate in a concentration of between 1.8 and 2.2 ppm, adjusting the pH to between 7.3 and 7.8 by adding CaCO/sub 3/ or other similar material, and adding a silicious material such as diatomaceous earth of a particle size of 5 to 15 microns to effect a suspension of between 2 and 300 ppm and circulating it through the reactor.

  7. Fully defined saltwater medium for cultivation of and toxicity testing with marine copepod Acartia tonsa

    SciTech Connect

    Kusk, K.O.; Wollenberger, L.

    1999-07-01

    The marine copepod Acartia tonsa and the food organism Rhodomonas salina were cultured in fully defined medium for 8 months without problems. Both organisms were also cultured in natural seawater and in a commercial salt mixture for at least two generations before the sensitivities of A. tonsa to bisphenol A, potassium dichromate, and 3,5-dichlorophenol in the three different media were compared and found to be at the same level. The defined medium may be used for cultivation and testing, thus avoiding unknown background contaminants.

  8. Effect of Drag Reducing Polymer and Suspended Solid on the Rate of Diffusion Controlled Corrosion in 90° Copper Elbow

    NASA Astrophysics Data System (ADS)

    Fouad, Mohamed Ahmed; Zewail, Taghreed Mohamed; Amine, Nieven Kamal Abbes

    2016-06-01

    Rate of diffusion controlled corrosion in 90° Copper Elbow acidified dichromate has been investigated in relation to the following parameters: effect of solution velocity in the absence and presence of drag- reducing polymer on the rate of diffusion controlled corrosion, and effect of the presence of suspended solids on the rate of diffusion controlled corrosion. It was found that the presence of drag reducing polymer inhibited the rate of mass transfer, while the presence of suspended solid increased significantly the rate of mass transfer.

  9. Atomic force microscopy observations of pitting corrosion and inhibition on 7075-T651 aluminum alloy in hydrochloric acid solutions

    SciTech Connect

    Josefowicz, J.Y.; Farrington, G.C.; DeLuccia, J.J.; Agarwala, V.S.

    1995-03-01

    Atomic force microscopy, a unique surface imaging technique that enables the effects of an imposed environment on the substrate to be measured and assessed, was used to define the effects of a dilute aqueous hydrochloric acid solution (0.03 N) on a polished and etched surface of a peak aged aluminum-zinc-magnesium alloy (7075-T651). A multifunctional corrosion inhibitor with dichromate, nitrite, borate, and molybdate ions, especially solubilized in an organic medium, was introduced to the study and its corrosion retardation effects were observed in situ by the atomic force microscope.

  10. A mathematical model of ionic transport in a porous diaphragm of a chrome-alum cell

    NASA Astrophysics Data System (ADS)

    Vidal, Roberto; Duby, Paul; West, Alan C.

    1994-06-01

    A model of the homogeneous chemistry and transport processes within the separator of a chrome-alum electrowinning cell is introduced, discussed, and compared to experiment. The influences of diffusion, electromigration, and convection are included; it is found that convection was the dominant mode of transport for the experimental conditions. Simulation results explain experimental observations concerning an apparent disappearance of dichromate ions produced at the cell anode. The relation between potential drop across the diaphragm and the current and fluid flow is also illustrated. The model is used to recommend future experimental and theoretical work.

  11. Reduction of hexavalent chromium by Sphaerotilus natans a filamentous micro-organism present in activated sludges.

    PubMed

    Caravelli, Alejandro H; Giannuzzi, Leda; Zaritzky, Noemí E

    2008-08-15

    Wastewaters produced by various industries may contain undesirable amounts of hexavalent chromium (Cr(VI)), as chromate and dichromate, a hazardous metal affecting flora and animals of aquatic ecosystems as well as human health. One removal strategy comprises the microbial reduction of Cr(VI) to Cr(III), a less soluble chemical species that is less toxic than Cr(VI). In this work, the ability to reduce Cr(VI) of Sphaerotilus natans, a filamentous bacterium usually found in activated sludge systems, was evaluated. In aerobic conditions, S. natans was able to efficiently reduce Cr(VI) to Cr(III) from dichromate solutions ranging between 4.5 and 80 mg Cr(VI)l(-1) in the presence of a carbonaceous source. A simultaneous evaluation of the microbial respiratory activity inhibition was also carried out to analyze the toxic effect of Cr(VI). Cr(VI) reduction by S. natans was mathematically modeled; chromium(VI) reduction rate depended on both Cr(VI) concentration and active biomass concentration. Although it is known that S. natans removes heavy metal cations such as Cr(III) by biosorption, the ability of this micro-organism to reduce Cr(VI), which behaves as an oxyanion in aqueous solutions, is a novel finding. The distinctive capacity to reduce Cr(VI) to Cr(III) than remain soluble or precipitated becomes S. natans a potential micro-organism to decontaminate wastewaters. PMID:18215460

  12. Impairment of Bony Crypt Development Associated With Hexavalent Chromium Exposure During Tooth Eruption.

    PubMed

    Sánchez, Luciana M; Lewicki, Marianela; De Lucca, Romina C; Ubios, Ángela M

    2015-12-01

    Improperly treated hexavalent chromium-containing industrial wastes contaminate drinking water, potentially affecting children taking breast milk or baby bottles prepared with infant formula. Thus, the aim of the present work was to determine the effect of this toxic on bone activity in the developing alveolus during tooth eruption of suckling Wistar rats intoxicated with potassium dichromate. Experimental animals received a daily dose of 12.5mg/kg body weight of potassium dichromate by gavage for 10 days; controls received an equivalent volume of saline solution. Histologic and histomorphometric studies of the mandible were performed. The data were statistically analyzed using Student's t test; statistical significance was set at a value of p <0.05. Experimental animals exhibited delayed tooth eruption, decreased periodontal width and bone volume, a lower percentage of bone formation surfaces, and higher percentage of quiescent surfaces (p<0.05) compared to controls. The delay in tooth eruption observed after exposure to hexavalent chromium is the result of a lower rate of bone remodeling in the developing alveolus. The obtained results show the importance of controlling toxic substances in drinking water, since their effects may alter the growth and development of subjects who were exposed during early infancy. PMID:27095619

  13. Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties.

    PubMed

    Madsen, Jakob Torp; Vogel, Stefan; Johansen, Jeanne Duus; Andersen, Klaus Ejner

    2011-06-01

    Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles. The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophilic contact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity of potassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulating isoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and in liposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. These results suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizing capacity of the encapsulated contact allergen. PMID:21198410

  14. Reduction of hexavalent chromium in aqueous medium with zerovalent iron.

    PubMed

    Dutta, Ratnadeepa; Mohammad, S Saker; Chakrabarti, Sampa; Chaudhuri, Basab; Bhattacharjee, Sekhar; Dutta, Binay K

    2010-02-01

    Hexavalent chromium, emanating primarily from the tannery and electroplating industries, can be reduced to the less toxic trivalent variety by several methods, including reduction with metallic iron. In the present work, electrolytic-grade iron dust was used to reduce chromium(VI) in the form of potassium dichromate. Loading of iron dust was varied from 0.5 to 1.0 g in 50 mL of solution; the pH of the medium was varied from 1.5 to 3.5; and the initial concentration of the dichromate solution was varied from 50 to 125 mg/L. Under the specified experimental conditions, maximum removal of the hexavalent chromium achieved was approximately 90% of its original value. The time-concentration data followed a pseudo-first-order kinetic model. The conversion and rate of reduction increased with an increase in iron loading and acidity of the medium, whereas an increase in the initial concentration of chromium(VI) caused a decrease in the reduction. PMID:20183980

  15. Cyto-histological and morpho-physiological responses of common duckweed (Lemna minor L.) to chromium.

    PubMed

    Reale, L; Ferranti, F; Mantilacci, S; Corboli, M; Aversa, S; Landucci, F; Baldisserotto, C; Ferroni, L; Pancaldi, S; Venanzoni, R

    2016-02-01

    Along with cadmium, lead, mercury and other heavy metals, chromium is an important environmental pollutant, mainly concentrated in areas of intense anthropogenic pressure. The effect of potassium dichromate on Lemna minor populations was tested using the growth inhibition test. Cyto-histological and physiological analyses were also conducted to aid in understanding the strategies used by plants during exposure to chromium. Treatment with potassium dichromate caused a reduction in growth rate and frond size in all treated plants and especially at the highest concentrations. At these concentrations the photosynthetic pathway was also altered as shown by the decrease of maximum quantum yield of photosystem II and the chlorophyll b content and by the chloroplast ultrastructural modifications. Starch storage was also investigated by microscopic observations. It was the highest at the high concentrations of the pollutant. The data suggested a correlation between starch storage and reduced growth; there was greater inhibition of plant growth than inhibition of photosynthesis, resulting in a surplus of carbohydrates that may be stored as starch. The investigation helps to understand the mechanism related to heavy metal tolerance of Lemna minor and supplies information about the behavior of this species widely used as a biomarker. PMID:26688244

  16. Ternary Hybrid γ-Fe2 O3 /Cr(VI) /Amine Oxidase Nanostructure for Electrochemical Sensing: Application for Polyamine Detection in Tumor Tissue.

    PubMed

    Bonaiuto, Emanuela; Magro, Massimiliano; Baratella, Davide; Jakubec, Petr; Sconcerle, Elisabetta; Terzo, Milo; Miotto, Giovanni; Macone, Alberto; Agostinelli, Enzo; Fasolato, Silvano; Venerando, Rina; Salviulo, Gabriella; Malina, Ondrej; Zboril, Radek; Vianello, Fabio

    2016-05-10

    Dichromate binds to surface-active maghemite nanoparticles (SAMNs) to form a stable core-shell nanostructures (SAMN@Cr(VI) ). The hybrid was characterized by Mössbauer spectroscopy, high-angle annular dark-field imaging, electron energy-loss spectroscopy, and electrochemical techniques, which revealed a strong interaction of dichromate with the nanoparticle surface. Electrochemical characterization showed lower charge-transfer resistance, better electrochemical performance, and more reversible electrochemical behavior with respect to naked SAMNs. Moreover, SAMN@Cr(VI) is an excellent electrocatalyst for hydrogen peroxide reduction. Furthermore, an enzyme, namely, bovine serum amine oxidase (BSAO: EC 1.4.3.6), was immobilized on SAMN@Cr(VI) by self-assembly to give a ternary hybrid nanostructured catalyst for polyamine oxidation (SAMN@Cr(VI) -BSAO). SAMN@Cr(VI) -BSAO was applied for the development of a reagentless, fast, inexpensive, and interference-free polyamine biosensor, which was successfully exploited for the discrimination of tumorous tissue from healthy tissue in human crude liver extracts. PMID:27060887

  17. A novel method developed for estimating mineralization efficiencies and its application in PC and PEC degradations of large molecule biological compounds with unknown chemical formula.

    PubMed

    Li, Guiying; Liu, Xiaolu; An, Taicheng; Wong, Po Keung; Zhao, Huijun

    2016-05-15

    A new method to estimate the photocatalytic (PC) and photoelectrocatalytic (PEC) mineralization efficiencies of large molecule biological compounds with unknown chemical formula in water was firstly developed and experimentally validated. The method employed chemical oxidation under the standard dichromate chemical oxygen demand (COD) conditions to obtain QCOD values of model compounds with unknown chemical formula. The measured QCOD values were used as the reference to replace QCOD values of model compounds for calculation of the mineralization efficiencies (in %) by assuming the obtained QCOD values are the measure of the theoretical charge required for the complete mineralization of organic pollutants. Total organic carbon (TOC) was also employed as a reference to confirm the mineralization capacity of dichromate chemical oxidation. The developed method was applied to determine the degradation extent of model compounds, such as bovine serum albumin (BSA), lecithin and bacterial DNA, by PC and PEC. Incomplete PC mineralization of all large molecule biological compounds was observed, especially for BSA. But the introduction of electrochemical technique into a PC oxidation process could profoundly improve the mineralization efficiencies of model compounds. PEC mineralization efficiencies of bacterial DNA was the highest, while that of lecithin was the lowest. Overall, PEC degradation method was found to be much effective than PC method for all large molecule biological compounds investigated, with PEC/PC mineralization ratios followed an order of BSA > lecithin > DNA. PMID:26994335

  18. Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

    NASA Technical Reports Server (NTRS)

    Kallenborn, K. J.; Emmons, J. R.

    1995-01-01

    Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.

  19. Chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract against chromium-induced testicular toxicity in rats.

    PubMed

    Sadek, K M

    2014-01-01

    This study was conducted to determine the mechanism underlying the chemotherapeutic efficacy of an ethanolic Moringa oleifera leaf extract (MOLEE) against chromium-induced impairments of rat testes using biochemical methods. Twenty male Wistar rats were divided into four groups of five animals each. Group I (control), group II injected potassium dichromate (8 mg kg(-1) ) i.p., group III gastrogavaged MOLEE (500 mg kg(-1) ) p.o. and group IV received (potassium dichromate plus MOLEE) by the same doses for 60 days. After the blood samples were collected, the animals were sacrificed to determine the testicular antioxidant status and sperm parameters. The chromium-treated group exhibited a significant decrease in testicular antioxidant enzymatic activities, local immunity and sperm parameters as well as an increase in inflammatory markers when compared with the control and MOLEE-treated group. However, concurrent administration of chromium and MOLEE significantly ameliorated the chromium effects on the sperm parameters, local immunity, inflammatory markers and antioxidant enzymatic activities compared with rats exposed to chromium alone. This study concludes that chronic exposure to chromium produces clear testicular toxicity, which can either be prevented or at least decreased by concomitant administration of MOLEE. Interestingly, the metal ion chelation could attribute partly the antioxidant activities of MOLEE. PMID:24215114

  20. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    PubMed

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept. PMID:20031309

  1. Holographic optical element for visual display applications.

    PubMed

    McCauley, D G; Simpson, C E; Murbach, W J

    1973-02-01

    Off-axis and off-bisector reflection-type holographic visual display elements have been recorded in dichromated gelatin deposited on planar or spherical shell substrates of glass or Plexiglas. A procedure for bonding gelatin to Plexiglas is given. Holographic elements are recorded at the argon wavelength of 514.5 nm and reconstructed with spectral lines from a low pressure mercury arc lamp. Measured image characteristics for a flat substrate hologram agree with ray-tracing calculations. A swelling of the gelatin by approximately 6.6% after processing does not perceptibly affect the dispersion, astigmatism, or distortion in the image, that is, the grating equation depends on the spacing between the fringes on the surface of the gelatin and is not affected by the swelling or shrinking. However, the Bragg equation depends on the distance normal to the fringe planes and is affected by thickness changes of the gelatin. Therefore, this thickness change is taken as an independent parameter and used to adjust the wavelength for maximum diffraction efficiency, without affecting the image angle. Data reveal a near linear relationship between the dichromate concentration of 0.5-10% used to photosensitive the gelatin and the display wavelength of maximum diffraction efficiency. Lateral dispersion is 0.12 +/- 0.01 degrees / nanometer for both planar and spherical shell substrate elements recorded in quite similar geometry, but their astigmatisms are not alike. PMID:20125273

  2. Measure of the diffraction efficiency of a holographic grating created by two Gaussian beams.

    PubMed

    Leclere, P; Renotte, Y; Lion, Y

    1992-08-10

    We present a methodology for analyzing the characteristics of a photosensitive material for holography. When two Gaussian beams of equal intensities are exactly superimposed on the recording material, the modulation of the interference pattern is equal to unity. When they are no longer exactly superimposed, this modulation varies from one to zero depending on the analyzed point. On the other hand, the modulation is constant in a direction that is perpendicular to the incident plane. Therefore it is possible to consider a complete analysis (point by point) of only one holographic grating to measure the diffraction efficiency eta at a given modulation versus exposure or for varying modulation (or beam ratio K) for a given exposure. We present the results that are obtained with an experimental setup that was devised for that purpose. From these measurements it was possible to extract various parameters such as refractive-index modulation of the photosensitive support. The tested recording materials consist of film of dichromated gelatin and films of dichromate polyvinyl alcohol. PMID:20725484

  3. Effects of soluble and particulate Cr(VI) on genome-wide DNA methylation in human B lymphoblastoid cells.

    PubMed

    Lou, Jianlin; Wang, Yu; Chen, Junqiang; Ju, Li; Yu, Min; Jiang, Zhaoqiang; Feng, Lingfang; Jin, Lingzhi; Zhang, Xing

    2015-10-01

    Several previous studies highlighted the potential epigenetic effects of Cr(VI), especially DNA methylation. However, few studies have compared the effects of Cr(VI) on DNA methylation profiles between soluble and particulate chromate in vitro. Accordingly, Illumina Infinium Human Methylation 450K BeadChip array was used to analyze DNA methylation profiles of human B lymphoblastoid cells exposed to potassium dichromate or lead chromate, and the cell viability was also studied. Array based DNA methylation analysis showed that the impacts of Cr(VI) on DNA methylation were limited, only about 40 differentially methylated CpG sites, with an overlap of 15CpG sites, were induced by both potassium dichromate and lead chromate. The results of mRNA expression showed that after Cr(VI) treatment, mRNA expression changes of four genes (TBL1Y, FZD5, IKZF2, and KIAA1949) were consistent with their DNA methylation alteration, but DNA methylation changes of other six genes did not correlate with mRNA expression. In conclusion, both of soluble and particulate Cr(VI) could induce a small amount of differentially methylated sites in human B lymphoblastoid cells, and the correlations between DNA methylation changes and mRNA expression varied between different genes. PMID:26433257

  4. Risk assessment for selected xenobiotics by bioassay methods with higher plants

    NASA Astrophysics Data System (ADS)

    Günther, Petra; Pestemer, Wilfried

    1990-05-01

    Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, thiourea), all from a list of reference chemicals, were tested with these methods. Dose-response curves for growth of oats and turnips were evaluated in soil and vermiculite (nonsorptive substrate), and availability to plants was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol, tested with turnips ( Brassica rapa var. rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress ( Lepidium sativum), was found with 2,6-dichlorobenzonitrile, the lowest with atrazine. The effect of an extended exposure of the plants to the chemicals was evaluated in a long-term bioassay with oats ( Avena sativa) in hydroponic culture. Several dose-response curves during the growing period were derived. It was found that the EC50 values for atrazine and thiourea decreased markedly during the first four weeks; thereafter the changes were much smaller. As an overall conclusion, a bioassay procedure is proposed that can be included in the graduated plan recommended by the German Chemicals Act.

  5. Analysis of organic sulfur and nitrogen in coal via tandem degradation methods. Technical report, 1 December 1992--28 February 1993

    SciTech Connect

    Kruge, M.A.; Palmer, S.R.; Ho, K.

    1993-05-01

    N/C and S/C ratios show only minor differences between asphaltenes and coal on this basis, the asphaltenes continue to appear to be good surrogates for the characterization of organic acid rain precursors in coal. Alkylmethoxythiophene carboxylic acids (ATCA) are detected in all dichromate oxidation products analyzed to date. Relative concentrations of ATCA compounds are directly proportional to the sample`s bulk organic sulfur contents. Concentrations of ATCA compounds in oxidation products decrease upon repeated oxidation. This may indicate that the thiophenic groups tend to be located in external positions on the coal macromolecular structure and a high proportion of them can be stripped away with only one mild oxidation step. If true, this may make industrial-scale removal of organic sulfur easier than expected. Using analytical micropyrolysis-gas chromatography with a sulfur-selective flame photometric detector, it is possible to easily see a full distribution of organic sulfur forms in a one-step analysis. The predominance of alkylthiophenes in the pyrolyzates lends credence to the discovery of thiophenic compounds in the dichromate oxidation products. The thiophene concentrations in pyrolyzates are directly proportional to bulk organic sulfur values. However, thiophene distributions in IBCSP coals are remarkably similar, regardless of organic sulfur content. It is thus possible to distinguish Illinois Basin coals from foreign coals on the basis of thiophene ``fingerprints.`` To examine rank effects, we have started analysis on a group of five Appalachian coals ranging from high-volatile C to medium-volatile bituminous rank.

  6. Determination of Mercury in Aqueous and Geologic Materials by Continuous Flow-Cold Vapor-Atomic Fluorescence Spectrometry (CVAFS)

    USGS Publications Warehouse

    Hageman, Philip L.

    2007-01-01

    New methods for the determination of total mercury in geologic materials and dissolved mercury in aqueous samples have been developed that will replace the methods currently (2006) in use. The new methods eliminate the use of sodium dichromate (Na2Cr2O7 ?2H2O) as an oxidizer and preservative and significantly lower the detection limit for geologic and aqueous samples. The new methods also update instrumentation from the traditional use of cold vapor-atomic absorption spectrometry to cold vapor-atomic fluorescence spectrometry. At the same time, the new digestion procedures for geologic materials use the same size test tubes, and the same aluminum heating block and hot plate as required by the current methods. New procedures for collecting and processing of aqueous samples use the same procedures that are currently (2006) in use except that the samples are now preserved with concentrated hydrochloric acid/bromine monochloride instead of sodium dichromate/nitric acid. Both the 'old' and new methods have the same analyst productivity rates. These similarities should permit easy migration to the new methods. Analysis of geologic and aqueous reference standards using the new methods show that these procedures provide mercury recoveries that are as good as or better than the previously used methods.

  7. Two novel calixarene functionalized iron oxide magnetite nanoparticles as a platform for magnetic separation in the liquid-liquid/solid-liquid extraction of oxyanions.

    PubMed

    Sayin, Serkan; Ozcan, Fatih; Yilmaz, Mustafa

    2013-05-01

    This article focuses on the syntheses of 25,27-bis[3-(N-ethylsulfonic acid)aminopropxy]-26,28-dihydroxy-5,11,17,23-tetra-tert-butyl-calix[4]arene (3) and 25,27-bis[3-(N-ethyl-dihydrogen phosphate)aminopropxy]-26,28-dihydroxy-5,11,17,23-tetra-tert-butyl-calix[4]arene (4) as well as their immobilization onto [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-modified Fe3O4 magnetite nanoparticles, and the extraction abilities of four new extractants which were characterized by a combination of FTIR, (1)H NMR, elemental analyses, transmission electron microscopy (TEM) and thermogravimetric analyses (TGA) involving electrostatic and hydrogen bonding interactions between the calixarene and oxide anions such as arsenate and dichromate anions. The extraction results indicate that these new calixarene derivatives having high extraction capabilities would be used as effective extractants for the removal of the dichromate/arsenate ions from water. PMID:23498279

  8. Interactions of chromium ions with starch granules in an aqueous environment.

    PubMed

    Szczygieł, Jadwiga; Dyrek, Krystyna; Kruczała, Krzysztof; Bidzińska, Ewa; Brożek-Mucha, Zuzanna; Wenda, Elżbieta; Wieczorek, Jerzy; Szymońska, Joanna

    2014-06-26

    In this study, interactions of dichromate ions with potato starch granules in highly acidic aqueous solutions and at different temperatures were investigated. It was found that the process underwent a reduction of Cr(2)O(7)(2-) to Cr(3+) accompanied by the formation of intermediate Cr(5+) ions detected by electron paramagnetic resonance (EPR) spectroscopy. The reactions took place after the attachment of dichromate anions to the granules and resulted in a lowering of the Cr(2)O(7)(2-) initial content in the solution. The newly formed Cr(3+) ions were both accumulated by the granules or remained in the solution. It was observed for the first time that the quantity of such ions taken by the granules from the solution was noticeably higher than that delivered by trivalent chromium salt solution. It was revealed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) that the chromium ions were not only adsorbed on the granule surface but also introduced into the granule interior and evenly distributed there. An activation energy of the reduction reaction equal to 65 kJ·mol(-1) and the optimal parameters of the process were established. The proposed mechanism could be useful for the bioremediation of industrial effluents polluted by hexavalent chromium compounds. PMID:24878058

  9. Preservation of Giardia cysts in stool samples for subsequent PCR analysis.

    PubMed

    Wilke, Hans; Robertson, Lucy J

    2009-09-01

    Genotyping of Giardia duodenalis cysts in faecal samples has become a regularly employed tool by researchers investigating different aspects of the epidemiology and pathology of Giardia infection in human and animal populations. However, such investigations are often limited to some extent by lack of PCR amplification from a proportion of the samples, and this often seems to be associated with the storage medium used for the samples. Various different storage media have been used in different studies, but investigation of which storage media are most appropriate and which may compromise subsequent PCR investigations has not been systematically explored to date. In this study, 4 different, commonly used storage media were investigated for their effects over time on subsequent PCR amplification of DNA from Giardia cysts in stool samples. Microscopic examination of the samples and real-time PCR were used to investigate 7 different samples over a period of 3 months. Our findings indicate that storage in ethanol or potassium dichromate at 4 degrees C gave the best results and, that if immunomagnetic separation was used prior to PCR (as may be appropriate for samples with low cyst numbers), then storage in potassium dichromate gave the best results. PMID:19576935

  10. Performance of volume phase holographic transmission grating recorded in DCG for PGP

    NASA Astrophysics Data System (ADS)

    Li, Ming; Tang, Minxue; Xia, Haohan; Fang, Chunhuan; Wu, Jianhong; Zhao, Xunjie

    2010-11-01

    The volume phase holographic (VPH) transmission grating recorded in dichromate gelatin (DCG) with a specific spectral coverage from 420 nm to 760 nm is designed for a novel prism-grating-prism imaging spectrometer. Based on the Rigorous Coupled-Wave Analysis, its performances are predicted and analyzed. The grating is manufactured and its properties are measured experimentally. The diffraction efficiency over the spectral range, the bandwidth, and the angular selectivity of the grating is measured, analyzed and compared with that of the theoretical ones. The results show that by adjusting and controlling the preparation conditions of DCG plates, the exposure time and the post-processing technique of the grating, the VPH transmission grating with high diffraction efficiency approximate to the design requirement can be obtained. The measured peak diffraction efficiency reaches nearly 85% at central wavelength of 590 nm while the average diffraction efficiency is larger than 75% over the required spectral range from 420 nm to 760 nm.

  11. Imaging spectrometer for process industry applications

    NASA Astrophysics Data System (ADS)

    Herrala, Esko; Okkonen, Jukka T.; Hyvarinen, Timo S.; Aikio, Mauri; Lammasniemi, Jorma

    1994-11-01

    This paper presents an imaging spectrometer principle based on a novel prism-grating-prism (PGP) element as the dispersive component and advanced camera solutions for on-line applications. The PGP element uses a volume type holographic plane transmission grating made of dichromated gelatin (DCG). Currently, spectrographs have been realized for the 400 - 1050 nm region but the applicable spectral region of the PGP is 380 - 1800 nm. Spectral resolution is typically between 1.5 and 5 nm. The on-axis optical configuration and simple rugged tubular optomechanical construction of the spectrograph provide a good image quality and resistance to harsh environmental conditions. Spectrograph optics are designed to be interfaced to any standard CCD camera. Special camera structures and operating modes can be used for applications requiring on-line data interpretation and process control.

  12. Health assessment for Coast Wood Preserving, Ukiah, Mendocino County, California, Region 9. CERCLIS No. CAD063015887. Preliminary report

    SciTech Connect

    Not Available

    1989-04-20

    The Coast Wood Preserving site is on the National Priorities List. Wood-preserving activity began at the site in 1971, and the facility has operated continuously up to the present. The wood-preserving operation at the site involves the use of a chemical mixture containing sodium dichromate, copper sulfate, and arsenic acid. Over the years, drippings from the treated wood are believed to have caused soil contamination at the site, particularly during the early years of operation when the treatment and treated-wood storage areas were not paved. Contamination of environmental media with chromium, arsenic, and copper was detected. The site is considered to be of potential health concern because of the risk to human health caused by the possibility of exposure to hazardous substances through the use of contaminated ground water and surface water for consumption and irrigation of agricultural crops.

  13. Hexavalent Chromium-Induced Apoptosis in Rat Uterus: Involvement of Oxidative Stress.

    PubMed

    Marouani, Neila; Tebourbi, Olfa; Mokni, Moncef; Yacoubi, Mohamed Tahar; Sakly, Mohsen; Benkhalifa, Moncef; Rhouma, Khémais Ben

    2015-01-01

    The present study is designed to test the hypothesis that oxidative stress mediates hexavalent chromium (VI)-induced apoptosis in uterus. Female Wistar rats received an intraperitoneal (i.p.) injection of potassium dichromate at doses of 1 and 2 mg/kg. Superoxide anion production was assessed by determination of the reduction of cytochrome c and iodonitrotetrazolium (INT), lipid peroxidation (LPO), metallothioneins (MTs), and catalase (CAT) activity. The expression of Bax and Bcl-2 proteins was investigated. After 15 days of treatment, an increase of LPO and MT levels occurred, whereas CAT activity decreased. Intense apoptosis was observed in endometriotic stromal cells of Cr-exposed rats. Bax protein expression was induced in endometriotic stromal cells with 1 mg of Cr(VI)/kg, and in stromal and epithelial cells at the higher dose. These results clearly suggest that Cr(VI) subacute treatment causes oxidative stress in rat uterus, leading to endometriotic stromal cells apoptosis. PMID:24965329

  14. Large-memory real-time multichannel multiplexed pattern recognition

    NASA Technical Reports Server (NTRS)

    Gregory, D. A.; Liu, H. K.

    1984-01-01

    The principle and experimental design of a real-time multichannel multiplexed optical pattern recognition system via use of a 25-focus dichromated gelatin holographic lens (hololens) are described. Each of the 25 foci of the hololens may have a storage and matched filtering capability approaching that of a single-lens correlator. If the space-bandwidth product of an input image is limited, as is true in most practical cases, the 25-focus hololens system has 25 times the capability of a single lens. Experimental results have shown that the interfilter noise is not serious. The system has already demonstrated the storage and recognition of over 70 matched filters - which is a larger capacity than any optical pattern recognition system reported to date.

  15. Holographic optical system for aberration corrections in laser Doppler velocimetry

    NASA Technical Reports Server (NTRS)

    Kim, R. C.; Case, S. K.; Schock, H. J.

    1985-01-01

    An optical system containing multifaceted holographic optical elements (HOEs) has been developed to correct for aberrations introduced by nonflat windows in laser Doppler velocimetry. The multifacet aberration correction approach makes it possible to record on one plate many sets of adjacent HOEs that address different measurement volume locations. By using 5-mm-diameter facets, it is practical to place 10-20 sets of holograms on one 10 x 12.5-cm plate, so that the procedure of moving the entire optical system to examine different locations may not be necessary. The holograms are recorded in dichromated gelatin and therefore are nonabsorptive and suitable for use with high-power argon laser beams. Low f-number optics coupled with a 90-percent efficient distortion-correcting hologram in the collection side of the system yield high optical efficiency.

  16. Determination of average refractive index of spin coated DCG films for HOE fabrication

    NASA Technical Reports Server (NTRS)

    Kim, T. J.; Campbell, Eugene W.; Kostuk, Raymond K.

    1993-01-01

    The refractive index of holographic emulsions is an important parameter needed for designing holographic optical elements (HOE's). Theoretical calculations of the accuracy required for the refractive index and thickness of emulsions needed to meet predetermined Bragg angle conditions are presented. A modified interferometric method is used to find average refractive index of the unexposed and the developed dichromated gelatin holographic films. Slanted transmission HOE's are designed considering the index and thickness variations, and used to verify the index measurement results. The Brewster angle method is used to measure surface index of the unexposed and the developed films. The differences between average index and surface index are discussed. Theoretical calculation of the effects of index variation on diffraction efficiency, and experimental results for index modulation variation caused by process changes are also presented.

  17. URANIUM DECONTAMINATION

    DOEpatents

    Buckingham, J.S.; Carroll, J.L.

    1959-12-22

    A process is described for reducing the extractability of ruthenium, zirconium, and niobium values into hexone contained in an aqueous nitric acid uranium-containing solution. The solution is made acid-deficient, heated to between 55 and 70 deg C, and at that temperature a water-soluble inorganic thiosulfate is added. By this, a precipitate is formed which carries the bulk of the ruthenium, and the remainder of the ruthenium as well as the zirconium and niobium are converted to a hexone-nonextractable form. The rutheniumcontaining precipitate can either be removed from the solu tion or it can be dissolved as a hexone-non-extractable compound by the addition of sodium dichromate prior to hexone extraction.

  18. Allergic contact dermatitis in children: review of the past decade.

    PubMed

    Admani, Shehla; Jacob, Sharon E

    2014-04-01

    Allergic contact dermatitis (ACD) is a type IV delayed hypersensitivity reaction. During the last decade, there has been a heightened awareness of this disease in the pediatric population. The gold standard for diagnosis is patch testing. The prevalence of positive patch tests in referred children with suspected ACD ranges from 27 to 95.6 %. The most common allergens in children in North America are nickel, neomycin, cobalt, fragrance, Myroxylon pereirae, gold, formaldehyde, lanolin/wool alcohols, thimerosal, and potassium dichromate. The relationship between ACD and atopic dermatitis (AD) is complicated with conflicting reports of prevalence in the literature; however, in a patient with dermatitis not responding to traditional therapies, or with new areas of involvement, ACD should be considered as part of the work-up. PMID:24504525

  19. Toxicity testing with the marine algae, Symbiodinium kawagutii (Dinophyceae)

    SciTech Connect

    Gorrie, J.R.; Bidwell, J.R.; Rippingale, R.J.

    1994-12-31

    The dinoflagellate, Symbiodinium kawagutii, is among the algal taxa which exist in symbiosis with a range of marine invertebrates. S. kawagutii is commonly found in association with the Hawaiian stony coral, Montipora verrucosa. The algae has been successfully cultured in the laboratory using a common marine algal growth media (Guillard f/2), and sufficient cell densities were achieved in a 96-hr bioassay to allow statistical evaluation of toxicity data. A 96-hr EC{sub 50} of 6.47 mg/L (95% C.I.: 3.54--9.88 mg/L) was calculated after exposure to potassium dichromate. Wide distribution of the coral host and ecological importance of the symbiosis make S. kawagutii an excellent candidate species for hazard evaluation in tropical marine ecosystems. Continuing research will seek to further refine the bioassay, including the use of a microplate technique for more rapid testing.

  20. Biological and chemical reactivity and phosphorus forms of buffalo manure compost, vermicompost and their mixture with biochar.

    PubMed

    Ngo, Phuong-Thi; Rumpel, Cornelia; Ngo, Quoc-Anh; Alexis, Marie; Velásquez Vargas, Gabriela; Mora Gil, Maria de la Luz; Dang, Dinh-Kim; Jouquet, Pascal

    2013-11-01

    This study characterized the carbon and phosphorus composition of buffalo manure, its compost and vermicompost and investigated if presence of bamboo biochar has an effect on their chemical and biological reactivity. The four substrates were characterized for chemical and biochemical composition and P forms. The biological stability of the four substrates and their mixtures were determined during an incubation experiment. Their chemical reactivity was analyzed after acid dichromate oxidation. Biological reactivity of these substrates was related to their soluble organic matter content, which decreased in the order buffalo manure>compost>vermicompost. Phosphorus was labile in all organic substrates and composting transformed organic P into plant available P. The presence of biochar led to a protection of organic matter against chemical oxidation and changed their susceptibility to biological degradation, suggesting that biochar could increase the carbon sequestration potential of compost, vermicompost and manure, when applied in mixture. PMID:24071441

  1. Lifetime and regeneration of immobilized titania for photocatalytic removal of aqueous hexavalent chromium.

    PubMed

    Tuprakay, Seree; Liengcharernsit, Winai

    2005-09-30

    Immobilized titania (TiO2) batch reactors reduced hexavalent chromium (Cr(VI)) in the form of potassium dichromate (K2Cr2O7) to trivalent chromium (Cr(III)) in aqueous solution at pH 3 under 171 W/m2 light intensity. The light source was a 125-W ultraviolet (UV) lamp. The Cr(VI) reduction showed zero-order kinetics (k0), while the Cr(VI) adsorption fitted with first-order kinetics (k(1st)). Adsorption capacity increased with increasing initial Cr(VI) concentration, and the area of immobilized TiO2 limited the reduction efficiency. The lifetime of fresh immobilized TiO2 was approximately 14 h. In addition, the regeneration of TiO2 with 3M sodium hydroxide (NaOH) was necessary to improve adsorption reaction. PMID:16046253

  2. SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

    DOEpatents

    Callis, C.F.; Moore, R.L.

    1959-09-01

    >The separation of ruthenium from aqueous solutions containing uranium plutonium, ruthenium, and fission products is described. The separation is accomplished by providing a nitric acid solution of plutonium, uranium, ruthenium, and fission products, oxidizing plutonium to the hexavalent state with sodium dichromate, contacting the solution with a water-immiscible organic solvent, such as hexone, to extract plutonyl, uranyl, ruthenium, and fission products, reducing with sodium ferrite the plutonyl in the solvent phase to trivalent plutonium, reextracting from the solvent phase the trivalent plutonium, ruthenium, and some fission products with an aqueous solution containing a salting out agent, introducing ozone into the aqueous acid solution to oxidize plutonium to the hexavalent state and ruthenium to ruthenium tetraoxide, and volatizing off the ruthenium tetraoxide.

  3. Process for producing gallium-containing solution from the aluminum smelting dust

    SciTech Connect

    Era, A.; Matsui, S.; Ikeda, H.

    1988-03-01

    A process is described for producing a gallium-containing solution from aluminum smelting dust comprising leaching aluminum smelting dust with a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid, and adding an oxidizing agent to the aluminum smelting dust at the time of leaching to preferentially leach and extract gallium from the aluminum smelting dust without extracting aluminum from the aluminum smelting dust. The oxidizing agent is selected from the group consisting of potassium permanganate, manganese dioxide, hydrogen peroxide, ozone, potassium chromate, potassium dichromate, ammonium persulfate, sodium hydrochlorite, sodium chlorite and sodium chlorate. The leached aluminum smelting dust is filtered to obtain a gallium-containing solution of dissolved gallium.

  4. Children with Atopic Dermatitis Should Always be Patch-tested if They Have Hand or Foot Dermatitis.

    PubMed

    Isaksson, Marléne; Olhardt, Sanna; Rådehed, Jeanette; Svensson, Åke

    2015-05-01

    Atopic dermatitis is the most common chronic inflammatory disease among children in industrialised countries. Many factors influence this disease in a negative way and contact allergy is one such factor. The aim of the study was to examine the frequency of contact allergy among children with the diagnosis atopic dermatitis. Contact allergy was found in 22/82 children (26.8%), the most common from Amerchol L101 (11.0%), potassium dichromate (7.3%), and nickel sulfate (4.9%). A statistically significant difference in contact allergy frequency was demonstrated for those with hand and/or foot eczema compared to those without. Children with atopic dermatitis who suffer from hand and/or foot dermatitis should always be patch-tested to evaluate whether they have a relevant contact allergy and thus allergic contact dermatitis. PMID:25367826

  5. Band-edge lasing and miniband lasing in 1-D dual-periodic photonic crystal

    NASA Astrophysics Data System (ADS)

    Ying, Cui-Feng; Zhou, Wen-Yuan; Li, Yi; Ye, Qing; Zhang, Chun-Ping; Tian, Jian-Guo

    2012-06-01

    Herein, we report two different dual-periodic Photonic Crystals (PCs) in dichromated gelatin emulsion which are fabricated by four-beam holography and double-exposure holography. The minibands with high Q-factors have been evidently located in both two structures. By taking into account the non-uniform distribution of material, the numerical results agree quite well with the experimental results. We also compared the band-edge lasing in single-periodic PC and miniband lasing in Moiré dual-periodic PC. Due to extremely flat dispersion and large mode volume of the miniband, high optical conversion efficiency in miniband lasing is achieved as compared with that of band-edge lasing. Such effect may provide potential applications in low-threshold lasers and ultra-sensitive fluorescent probes in biological assays.

  6. PROCESS USING BISMUTH PHOSPHATE AS A CARRIER PRECIPITATE FOR FISSION PRODUCTS AND PLUTONIUM VALUES

    DOEpatents

    Finzel, T.G.

    1959-03-10

    A process is described for separating plutonium from fission products carried therewith when plutonium in the reduced oxidation state is removed from a nitric acid solution of irradiated uranium by means of bismuth phosphate as a carrier precipitate. The bismuth phosphate carrier precipitate is dissolved by treatment with nitric acid and the plutonium therein is oxidized to the hexavalent oxidation state by means of potassium dichromate. Separation of the plutonium from the fission products is accomplished by again precipitating bismuth phosphate and removing the precipitate which now carries the fission products and a small percentage of the plutonium present. The amount of plutonium carried in this last step may be minimized by addition of sodium fluoride, so as to make the solution 0.03N in NaF, prior to the oxidation and prccipitation step.

  7. Patch-test results in children and adolescents: systematic review of a 15-year period*

    PubMed Central

    Rodrigues, Dulcilea Ferraz; Goulart, Eugênio Marcos Andrade

    2016-01-01

    The number of studies on patch-test results in children and adolescents has gradually increased in recent years, thus stimulating reviews. This paper is a systematic review of a 15-year period devoted to studying the issue. Variations pertaining to the number and age groups of tested children and/or adolescents, the number of subjects with atopy/atopic dermatitis history, the quantity, type and concentrations of the tested substances, the test technique and type of data regarding clinical relevance, must all be considered in evaluating these studies, as they make it harder to formulate conclusions. The most common allergens in children were nickel, thimerosal, cobalt, fragrance, lanolin and neomycin. In adolescents, they were nickel, thimerosal, cobalt, fragrance, potassium dichromate, and Myroxylon pereirae. Knowledge of this matter aids health professionals in planning preventive programs aimed at improving children's quality of life and ensuring that their future prospects are not undermined. PMID:26982781

  8. Holograms of fluorescent albumin

    NASA Astrophysics Data System (ADS)

    Ordóñez-Padilla, M. J.; Olivares-Pérez, A.; Berriel-Valdos, L. R.; Mejias-Brizuela, N. Y.; Fuentes-Tapia, I.

    2011-09-01

    We report the characterization and analysis of photochromic films gallus gallus albumin as a matrix modified for holographic recording. Photo-oxidation of homogeneous mixtures prepared with albumin-propylene glycol, to combine chemically with aqueous solution of ammonium dichromate at certain concentrations. We analyzed the diffraction gratings, through the diffraction efficiency of the proposed material. Also, eosin was used as a fluorescent agent, so it is found that produces an inhibitory effect, thus decreasing the diffraction efficiency of the matrices prepared in near-identical circumstances. The work was to achieve stability of albumin films, were prepared with propylene glycol. Finally, experimental studies were performed with films when subjected to aqueous solution of eosin (fluorescent agent) to verify the ability to increase or decrease in diffraction efficiency.

  9. Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry.

    PubMed

    Sohrabpour, M; Hassanzadeh, M; Shahriari, M; Sharifzadeh, M

    2002-10-01

    The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators. PMID:12361333

  10. Preliminary results from the investigation of thermal effects in electrokinetics soil remediation

    SciTech Connect

    Krause, T.R.; Tarman, B.

    1993-10-01

    Electrokinetics is an emerging soil remediation technology. Contaminants are extracted from the soil as a result of a complex set of phenomena that occur when an electric gradient is imposed across a soil-water system. The primary phenomena include electroosmosis, electromigration, and electrophoresis. Secondary phenomena, such as changes in solubility or speciation of various chemical components, may occur as a result of electrically induced changes in the chemical environment of the system. Numerous factors, such as temperature, may affect each of these phenomena and, consequently, the overall process efficiency. We have begun an investigation of thermal effects in the extraction of potassium dichromate from kaolinite soils under conditions of constant saturation and dewatering. Preliminary results suggest that increasing the soil temperature from 21 to 55{degrees}C may decrease the processing time under saturated conditions. However, increasing the soil temperature under dewatering, conditions causes soil cracking, which reduces the overall process efficiency.

  11. Fertilizers and Mixed Crop Cultivation of Chromium Tolerant and Sensitive Plants under Chromium Toxicity

    PubMed Central

    Dheeba, B.; Sampathkumar, P.; Kannan, K.

    2015-01-01

    Zea mays (maize) and Vigna radiata (green gram) are found to be the chromium (Cr) tolerant and sensitive plants, respectively. In the present paper, we investigate the reduction of the toxicity of Cr in the sensitive plants by the mixed crop cultivation in the field using various amendments. Further, the potassium dichromate was used as the source of hexavalent Cr. The results indicated that Cr adversely affects both the growth and yield of plants. The soil properties vary with Cr and different fertilizer amendments and the yield of both plants were affected by Cr. We conclude that metal accumulation of seeds of green gram was higher than corn and the application of single fertilizer either farm yard manure (FYM) or nitrogen, phosphorous, and potassium (NPK) enhances the growth and yield of both the tolerant and sensitive plants in the mixed crop cultivations. PMID:25709647

  12. Novel cone lasing emission in a non-uniform one-dimensional photonic crystal

    NASA Astrophysics Data System (ADS)

    Li, Yi; Zhou, Wen-Yuan; Ying, Cui-Feng; Yang, Na; Chen, Shao-Jie; Ye, Qing; Tian, Jian-Guo

    2015-06-01

    Novel cone lasing emission is observed from a photonic crystal (PC) with graded layers, which is fabricated by two-beam holographic interference in dichromated gelatin. The cone lasing is composed of one lasing spot and one concentric lasing ring. The good agreement between the experimental results and a numerical simulation performed using the transfer matrix method demonstrates that this lasing ring is induced by the coupling between the band edge and minigap, which is represented as some oscillations near the band edge in the passband of the reflection spectrum. The cone lasing may be useful for multi-wavelength fluorescence detection since the dual-colour directional enhanced fluorescence can be achieved without the mutual interference of lasing modes. Moreover, this readily observable cone lasing provides a direct visualization of the dispersion relation of non-uniform PCs.

  13. Effects of metal ions and CCl/sub 4/ on sea urchin embryo (Paracentrotus lividus)

    SciTech Connect

    Congiu, A.M.; Calendi, E.; Ugazio, G.

    1984-02-01

    The determination of embryotoxicity is an experimental tool for detecting the risks of environmental pollutants. In this study, fertilized eggs of sea urchin have been observed morphologically during exposure to heavy metal salts or carbon tetrachloride, with the purpose of testing possible differences in toxicity of various classes of poisons. Mercuric chloride is the most active salt, still harmful at 0.25 x 10(-6) M, while potassium dichromate, cadmium chloride and lead nitrate block embryo development at concentrations ranging between 0.25 x 10(-4) and 0.25 x 10(-5) M. Carbon tetrachloride per se does not affect the gastrulation at concentrations up to 3,520 ppm, and fails in potentiating the toxicity of the studied metal salts. The selective susceptibility of the development phases of sea urchin embryos to different compounds renders this simple morphological study a sensitive and reliable model for predicting the toxicity of environmental pollutants.

  14. Applicability study on existing dosimetry systems to high-power Bremsstrahlung irradiation

    NASA Astrophysics Data System (ADS)

    Mehta, Kishor; Kojima, Takuji; Sunaga, Hiromi

    2003-12-01

    Applicability of the existing dosimetry systems to high-power Bremsstrahlung irradiation was investigated through a dose intercomparison study, where several dosimeters were irradiated in the dose range 4-12 kGy in identical polyethylene phantoms in a Bremsstrahlung beam obtained from a 5-MeV electron accelerator. Included in the study were alanine dosimeters molded by three different binders, three types of liquid dosimeters—ceric-cerous, dichromate and ethanol-chlorobenzen (ECB), and glutamine powder. The dosimeter responses for Bremsstrahlung radiation were analyzed at the issuing laboratories, and the dose values determined using calibration based on cobalt-60 gamma-ray irradiation. Dose values for all the three dose levels for all dosimetry systems were in good agreement—better than 3%. The results of the study demonstrate that these existing dosimetry systems have a potential for application to high-power Bremsstrahlung irradiation.

  15. Holographic perfect shuffle permutation element for a miniaturized switching network

    NASA Astrophysics Data System (ADS)

    Kobolla, H.; Schmidt, J.; Gluch, E.; Schwider, J.

    1995-06-01

    A holographic perfect shuffle element with 80 channels for a miniaturized switching network is reported. An array of vertical-cavity, surface-emitting lasers is used as a transmitter. The whole permutation is carried out totally in glass. The 80 channels are permuted within a rectangle with a volume of 3 mm \\times 4 mm \\times 2 mm. Four planes of stacked volume holograms recorded in dichromated gelatin form this perfect shuffle element with an angular spectrum between 7 deg and 35 deg. Changes in the wavelength of the diode lasers to Delta lambda = +/-10 nm can be compensated with this setup. The overall efficiency per channel lies between 40% and 60%. When Fresnel reflections and absorption are taken into account, a transmission per hologram between 78% and 90% is achieved.

  16. Microfluidic Fabrication of Hydrogel Microparticles Containing Functionalized Viral Nanotemplates

    PubMed Central

    Lewis, Christina L.; Lin, Yan; Yang, Cuixian; Manocchi, Amy K.; Yuet, Kai P.; Doyle, Patrick S.; Yi, Hyunmin

    2010-01-01

    We demonstrate rapid microfluidic fabrication of hybrid microparticles composed of functionalized viral nanotemplates directly embedded in polymeric hydrogels. Specifically, genetically modified tobacco mosaic virus (TMV) templates were covalently labeled with fluorescent markers or metalized with palladium (Pd) nanoparticles (Pd-TMV), then suspended in a poly(ethylene glycol)-based solution. Upon formation in a flow-focusing device, droplets were photopolymerized with UV light to form microparticles. Fluorescence and confocal microscopy images of microparticles containing fluorescently labeled TMV show uniform distribution of TMV nanotemplates throughout the microparticles. Catalytic activity, via the dichromate reduction reaction, is also demonstrated with microparticles containing Pd-TMV complexes. Additionally, Janus microparticles were fabricated containing viruses embedded in one side and magnetic nanoparticles in the other, that enabled simple separation from bulk solution. These results represent a facile route to directly harness the advantages of viral nanotemplates into a readily usable and stable 3D assembled format. PMID:20695589

  17. A Water-Stable Cationic Metal-Organic Framework as a Dual Adsorbent of Oxoanion Pollutants.

    PubMed

    Desai, Aamod V; Manna, Biplab; Karmakar, Avishek; Sahu, Amit; Ghosh, Sujit K

    2016-06-27

    A three-dimensional water-stable cationic metal-organic framework (MOF) pillared by a neutral ligand and with Ni(II)  metal nodes has been synthesized employing a rational design approach. Owing to the ordered arrangement of the uncoordinated tetrahedral sulfate (SO4 (2-) ) ions in the channels, the compound has been employed for aqueous-phase ion-exchange applications. The compound exhibits rapid and colorimetric aqueous-phase capture of environmentally toxic oxoanions (with similar geometries) in a selective manner. This system is the first example of a MOF-based system which absorbs both dichromate (Cr2 O7 (2-) ) and permanganate (MnO4 (-) ) ions, with the latter acting as a model for the radioactive contaminant pertechnetate (TcO4 (-) ). PMID:26855323

  18. A Cause of Chromate Dermatitis among Assemblers in an Automobile Factory

    PubMed Central

    Newhouse, Muriel L.

    1963-01-01

    A series of 230 patients with skin disease and 66 men with no skin disease were tested with a battery of nine common sensitizing substances. Among the patients the incidence of positive reactions was 36%, whereas in the control series it was 7·6%. The most common sensitizing agent was potassium dichromate. The incidence of chromate sensitivity was four times greater among assemblers than among men in other jobs. Hexavalent chromate was found on the surface of the nuts, bolts, screws, and washers used by the assemblers. The source of the chromate was a chromate dip which is used as a passivator in chromium plating and zinc coating. The process was modified in one department and the chromate dip omitted. Patch testing of 12 men who had developed dermatitis since the modification of the process revealed no further cases of chromate sensitivity. This cause of allergic dermatitis appears to have been eliminated from this department. PMID:14046156

  19. Viability staining and animal infectivity of Cryptosporidium andersoni oocysts after long-term storage.

    PubMed

    Kvác, Martin; Kvetonová, Dana; Salát, Jirí; Ditrich, Oleg

    2007-01-01

    Preservation of biological properties of oocysts during the storage is critical for experimental work. Stomach species of cryptosporidia are less resistant against external influences, and their infectivity decreases rapidly in comparison with intestinal cryptosporidia. Cryptosporidium andersoni oocysts lost their infectivity for gerbil (Meriones unguiculatus) after 7 months storage in deionised water (DW) or in 2.5% potassium dichromate solution (PDS). Evaluation of oocyst viability by flow cytometry indicates higher percentage of viable oocysts stored in PDS than in DW, particularly after 6 months of storage. However, direct counting using fluorescent microscope revealed that these results are false and are influenced by the change of staining properties during the storage in PDS. Moreover, the examination of oocyst integrity by flow cytometry revealed that oocysts preserved in PDS kept their wall integrity longer than those stored in DW, and this fact should be taken into consideration during quantification of oocyst survival. PMID:17024363

  20. Patch-test results in children and adolescents: systematic review of a 15-year period.

    PubMed

    Rodrigues, Dulcilea Ferraz; Goulart, Eugênio Marcos Andrade

    2016-02-01

    The number of studies on patch-test results in children and adolescents has gradually increased in recent years, thus stimulating reviews. This paper is a systematic review of a 15-year period devoted to studying the issue. Variations pertaining to the number and age groups of tested children and/or adolescents, the number of subjects with atopy/atopic dermatitis history, the quantity, type and concentrations of the tested substances, the test technique and type of data regarding clinical relevance, must all be considered in evaluating these studies, as they make it harder to formulate conclusions. The most common allergens in children were nickel, thimerosal, cobalt, fragrance, lanolin and neomycin. In adolescents, they were nickel, thimerosal, cobalt, fragrance, potassium dichromate, and Myroxylon pereirae. Knowledge of this matter aids health professionals in planning preventive programs aimed at improving children's quality of life and ensuring that their future prospects are not undermined. PMID:26982781

  1. Environmental contamination of chromium in agricultural and animal products near a chromate industry

    SciTech Connect

    Khasim, D.I. ); Kumar, N.V.N.; Hussain, R.C. )

    1989-11-01

    India is one of the largest leather exporting countries. Accordingly the important raw material required for leather tanning, namely sodium dichromate production, has also been boosted in some states of India. Investigations on irrigation reservoirs, irrigation wells and soil revealed high level contamination of chromium. There was no effluent treatment plant installed and effluents stored in earthen lagoons without cement lining caused contamination of underground aquafers. There is little information on the biomagnification and movement of toxic chromate compounds from the contaminated soil and water resources into the components of the foodchain which might ultimately reach humans. Hence an analysis of chromium was carried out in some commercial plants cultivated in these areas and also in some animal products and foods like milk and fishes.

  2. The gelation mechanism of chromium(III)

    SciTech Connect

    Shu, P.

    1988-05-01

    Chromium(III) is commonly used crosslinker for preparing profile control gels with polymers having carboxylate and amide functionalities. Cr(III) is applied in many forms. For example, it can be used in the form of simple chromic salts of chloride and sulfate, or as complexed Cr(III) used in leather tanning, or as in-situ generated Cr(III) from the redox reaction of dichromate and bisulfite or thiourea. The gelation rate, and gel quality, doped on which form of Cr(III) is used. The author has found that the Cr olates, produced by hydrolysis of Cr(III) ions, are the reactive crosslinking species. The different gelation rates are due to the different degrees of olation. Furthermore, by controlling the degree of hydrolysis Cr(III) derived from various sources mentioned above can exhibit the same gelation rate.

  3. Occupational asthma due to chromium.

    PubMed

    Leroyer, C; Dewitte, J D; Bassanets, A; Boutoux, M; Daniel, C; Clavier, J

    1998-01-01

    We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated. PMID:9782225

  4. Superfund record of decision (EPA Region 5): Peerless Plating, Muskegon Township, MI. (First remedial action), September 1992. Final report

    SciTech Connect

    Not Available

    1992-09-21

    The 1-acre Peerless Plating site is a former electroplating facility in Muskegon Township, Michigan, and is located northwest of Little Black Creek and 1 mile north of Mona Lake. Lake Michigan supplies drinking water for residential and commercial businesses within a 3-mile radius of the site. From 1937 to 1983, onsite electroplating operations and processes included copper, nickel, chromium, cadmium, and zinc plating, in addition to burnishing, polishing, pickling, oiling, passivating, stress relieving, and dichromate dipping. In the 1970s, the state directed Peerless Plating to monitor waste discharge daily and to install a treatment system to meet reduced effluent limitations. The site violated the requirements and was charged by the state. The ROD addresses the onsite contaminated soil and ground water as a final remedy. The primary contaminants of concern are VOCs, including benzene, TCE, toluene, and xylenes; metals, including arsenic, chromium, and lead; and inorganics, including cyanide. The selected remedial action for the site are included.

  5. Practical holography IV; Proceedings of the Meeting, LOS Angeles, CA, Jan. 18, 19, 1990

    NASA Astrophysics Data System (ADS)

    Benton, Stephen A.

    1990-05-01

    Various papers on practical holography are presented. Individual topics addressed include: dichromated gelatin for holographic optical elements, novel enhancement of photopolymers, photopolymers for holography, new rehalogenating bleach for the production of Lippmann holograms, effects of bleach constituents on the performance of silver-halide holograms, highly sensitive positive resists for holography, holographic 3-D printer, generation of high-quality holograms with liquid-crystal SLM, display holography for medical tomography, 3-D display of ultrasound B-mode image by holographic stereogram, edge-lit rainbow holograms, electronic display system for computational holography, and DCG recording with red light. Also discussed are: corneal topography via two-wavelength holography, optically produced cylindrical HOEs for signal-processing applications, hybrid diffractive-refractive telescope, volume IR reflective gratings, holographic lithography for microcircuits, photorefractive waveguide grating switches for optical interconnects, non-Fourier computer-generated holography for 3-D display, phase selection in binary-phase-only filters for optical pattern recognition.

  6. False-positive, follicular and irritant patch test reactions to metal salts.

    PubMed

    Fischer, T; Rystedt, I

    1985-02-01

    853 hard metal workers were patch tested with nickel sulphate 5%, potassium dichromate 0.5% and cobalt chloride 1%, each in petrolatum. Non-allergic reactions appeared in 6.5% of the nickel tests, 13% of the chromium tests and 18.3% of the cobalt tests. Most of the individuals with positive, poral or pustular reactions were retested with serial dilutions of metal salts in pet. and in water. The accuracy of a positive initial nickel reaction was 83%, a chromium reaction 40% and a cobalt reaction 62%. The nonallergic reactions were partly reproducible and correlated with both the type of patch test material and with individual factors. Weak and moderately strong positive patch test reactions to metal salts may be irritant and should be checked with serial dilution tests or at least be retested. A reduction of the cobalt chloride concentration from 1% to 0.5% in the standard test material is discussed. PMID:3157537

  7. Dual fluorescent molecular substrates selectively report the activation, sustainability and reversibility of cellular PKB/Akt activity

    NASA Astrophysics Data System (ADS)

    Shen, Duanwen; Bai, Mingfeng; Tang, Rui; Xu, Baogang; Ju, Xiaoming; Pestell, Richard G.; Achilefu, Samuel

    2013-04-01

    Using a newly developed near-infrared (NIR) dye that fluoresces at two different wavelengths (dichromic fluorescence, DCF), we discovered a new fluorescent substrate for Akt, also known as protein kinase B, and a method to quantitatively report this enzyme's activity in real time. Upon insulin activation of cellular Akt, the enzyme multi-phosphorylated a single serine residue of a diserine DCF substrate in a time-dependent manner, culminating in monophospho- to triphospho-serine products. The NIR DCF probe was highly selective for the Akt1 isoform, which was demonstrated using Akt1 knockout cells derived from MMTV-ErbB2 transgenic mice. The DCF mechanism provides unparalleled potential to assess the stimulation, sustainability, and reversibility of Akt activation longitudinally. Importantly, NIR fluorescence provides a pathway to translate findings from cells to living organisms, a condition that could eventually facilitate the use of these probes in humans.

  8. Fiber-optic wavelength-division multiplexing and demultiplexing using volume holographic gratings

    SciTech Connect

    Moslehi, B.; Harvey, P.; Ng, J.; Jannson, T. )

    1989-10-01

    We present theoretical and experimental results of a novel fiber-optic wavelength-division multiplexing (WDM) design employing a broadband (>150-nm) dichromated gelatin volume holographic grating operating in a reflective Littrow configuration with on-axis optics, a single lens, and one fiber array. This configuration can achieve better than {minus}1.5-dB insertion loss and {minus}40-dB cross talk for a 6-channel system and {minus}2.5-dB insertion loss and {minus}20-dB cross talk for a 12-channel system with 15-nm channel spacing. For an experimental 4-channel WDM unit we measured better than {minus}1.5-dB insertion loss for all channels and less than {minus}32-dB cross talk. This design can provide cost and performance benefits for local area network communication applications.

  9. Assessment of Exposure to Alcohol Vapor from Alcohol-Based Hand Rubs

    PubMed Central

    Bessonneau, Vincent; Thomas, Olivier

    2012-01-01

    This study assessed the inhaled dose of alcohol during hand disinfection. Experiments were conducted with two types of hand rub using two hand disinfection procedures. Air samples were collected every 10 s from the breathing zone, by bubbling through a mixture of K2Cr2O7 and H2SO4. The reduction of dichromate ions in the presence of alcohols was followed by UV-vis spectrophotometry. The difference in intensity of the dichromate absorption peak was used to quantify the alcohol concentration expressed in ethanol equivalent. During hygienic hand disinfection, the mean ethanol equivalent concentrations peaked at around 20–30 s for both hand rubs (14.3 ± 1.4 mg/L for hand rub 1 and 13.2 ± 0.7 mg/L for hand rub 2). During surgical hand disinfection, two peaks were found at the same time (40 and 80 s) for both hand rubs. The highest mean concentrations were 20.2 ± 0.9 mg/L for hand rub 1 and 18.1 ± 0.9 mg/L for hand rub 2. For hand rub 1, the total absorbed doses, calculated from ethanol with an inhalation flow of 24 L/min and an absorption rate of 62%, were 46.5 mg after one hygienic hand disinfection and 203.9 mg after one surgical hand disinfection. Although the use of ABHRs leads to the absorption of very low doses, sudden, repeated inhalation of high alcohol concentrations raises the question of possible adverse health effects. PMID:22690169

  10. Contact Allergens Causing Hand Eczema in Ethnic Kashmiri Population: A Study of 7-years

    PubMed Central

    Majid, Imran

    2016-01-01

    Background: Hand eczema is one of the commonest eczemas encountered in dermatology practice. Contact allergens responsible for causing hand eczema vary from one geographical area of the world to another. Aim: The study tries to identify the commonest allergens causing hand eczema in ethnic Kashmiri population. Material and Methods: A total of 800 patients were patch tested at a sole patch testing facility for the local population over a 7-year period out of which 278 were diagnosed with hand eczema. The morphological type of hand eczema was noted and the patch testing results were analyzed. Past or present relevance of the patch-test result to the clinical diagnosis was also analyzed. Results: Hand eczema was the most common type of eczema patch tested over the 7-year period, constituting 34.75% of the patch-tested population. A positive patch-test result was obtained in 135 patients (48.5%) out of which it was found to be clinically relevant in about 65% cases. Nickel and potassium dichromate were found to be the two commonest allergens causing hand eczema in our population with positive patch test reactions in 45 and 27 patients respectively. Females showed a much higher incidence of hand eczema as well as higher patch test positivity than males (54.1% vs. 38.1%). Conclusions: Hand eczema with a positive patch-test report was found to be much more common in females than males and nickel and potassium dichromate were seen to be the commonest allergens causing hand eczema in ethnic Kashmiri population. PMID:26955125

  11. Embryotoxic effects of environmental chemicals: tests with the South African clawed toad (Xenopus laevis)

    SciTech Connect

    Dumpert, K.

    1987-06-01

    In the course of the investigations reported below, it was shown that p-chloroaniline has a lethal effect on the embryos of Xenopus laevis at a concentration of 100 ppm and is development inhibiting (teratogenic) at concentrations of 1 and 10 ppm, respectively. In the case of aniline, a significant development-inhibiting effect was observed at a concentration as low as 1 ppm. A toxic effect was caused by concentrations between 30 and 40 ppm during embryogenesis and by concentrations above 40 ppm during larval development. A very conspicuous finding was an inhibiting effect of 20 to 40 ppm aniline on pigmentation during embryogenesis and of a concentration as low as 1 ppm on the body size of the young toads. In the case of potassium dichromate, it was possible to barely detect a weak development-inhibiting effect during embryogenesis but no development-retarding effect during larval development. Toxic effects of potassium dichromate occurred during embryogenesis at concentrations of 5 and 7.5 ppm and during the larval development at concentrations above 10 ppm. Sodium dodecylbenzenesulfonic acid at a concentration of 50 ppm was found to have such a strong embryolethal effect that 80% of the eggs showed no cell division at all and the remaining 20% developed to only the bicellular stage. A teratogenic effect of this substance was not observed. Phenol, too, was found to be toxic at a concentration of 50 ppm; in contrast to sodium dodecylbenzenesulfonic acid, however, it did not show any lethal effect on the embryos but it did on the tadpoles, mainly in the first stages of larval development. Lower concentrations of phenol (5 and 10 ppm) had a nonsignificant inhibiting effect on the growth of the larvae. A teratogenic effect of phenol was not detected.

  12. Lactational exposure to hexavalent chromium delays puberty by impairing ovarian development, steroidogenesis and pituitary hormone synthesis in developing Wistar rats

    SciTech Connect

    Banu, Sakhila K. Samuel, Jawahar B.; Arosh, Joe A.; Burghardt, Robert C.; Aruldhas, Michael M.

    2008-10-15

    Hexavalent chromium (Cr-VI) is used in a wide range of industries. Cr-VI from chromate industries and atmospheric emissions contribute to the Cr contamination in the environment. Cr is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects including ovotoxicity. Therefore, the goal of this study was to investigate the basic mechanisms involved in Cr(VI)-induced ovotoxicity, and the protective role of vitamin C on ovarian follicular development and function in Cr(VI)-induced reproductive toxicity using both in vivo and in vitro approaches. Lactating rats received potassium dichromate (200 mg/L) with or without vitamin C (500 mg/L), through drinking water from postpartum days 1-21. During postnatal days (PND) 1-21 the pups received Cr(VI) via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards, and euthanized on PND-21, -45 and -65. Cr(VI) decreased steroidogenesis, GH and PRL, increased FSH and did not alter LH. Cr(VI) delayed puberty, decreased follicle number, and extended estrous cycle. Spontaneously immortalized rat granulosa cells were treated with 12.5 {mu}M (IC{sub 50}) potassium dichromate for 12 and 24 h, with or without vitamin C pre-treatment. Cr(VI) decreased the mRNA expressions of StAR, SF-1, 17{beta}-HSD-1, 17{beta}-HSD-2, FSHR, LHR, ER{alpha} and ER{beta}. Vitamin C pre-treatment protected ovary and granulosa cells from the deleterious effects of Cr(VI) toxicity, both in vivo and in vitro. Therefore, Cr(VI) toxicity could be a potential risk to the reproductive system in developing females, and vitamin C plays a protective role against Cr(VI)-induced ovotoxicity.

  13. CONCENTRATION AND DECONTAMINATION OF SOLUTIONS CONTAINING PLUTONIUM VALUES BY BISMUTH PHOSPHATE CARRIER PRECIPITATION METHODS

    DOEpatents

    Seaborg, G.T.; Thompson, S.G.

    1960-08-23

    A process is given for isolating plutonium present in the tetravalent state in an aqueous solution together with fission products. First, the plutonium and fission products are coprecipitated on a bismuth phosphate carrier. The precipitate obtained is dissolved, and the plutonium in the solution is oxidized to the hexavalent state (with ceric nitrate, potassium dichromate, Pb/ sub 3/O/sub 4/, sodium bismuthate and/or potassium dichromate). Thereafter a carrier for fission products is added (bismuth phosphate, lanthanum fluoride, ceric phosphate, bismuth oxalate, thorium iodate, or thorium oxalate), and the fission-product precipitation can be repeated with one other of these carriers. After removal of the fission-product-containing precipitate or precipitates. the plutonium in the supernatant is reduced to the tetravalent state (with sulfur dioxide, hydrogen peroxide. or sodium nitrate), and a carrier for tetravalent plutonium is added (lanthanum fluoride, lanthanum hydroxide, lanthanum phosphate, ceric phosphate, thorium iodate, thorium oxalate, bismuth oxalate, or niobium pentoxide). The plutonium-containing precipitate is then dissolved in a relatively small volume of liquid so as to obtain a concentrated solution. Prior to dissolution, the bismuth phosphate precipitates first formed can be metathesized with a mixture of sodium hydroxide and potassium carbonate and plutonium-containing lanthanum fluorides with alkali-metal hydroxide. In the solutions formed from a plutonium-containing lanthanum fluoride carrier the plutonium can be selectively precipitated with a peroxide after the pH was adjusted preferably to a value of between 1 and 2. Various combinations of second, third, and fourth carriers are discussed.

  14. A Commercial Device Involving the Breathalyzer Test Reaction

    NASA Astrophysics Data System (ADS)

    Dombrink, Kathleen J.

    1996-02-01

    The breathalyzer test, formerly used by law-enforcement agencies to determine the percentage blood alcohol in suspected DUI cases, is still used in the device FINAL CALL, which is available commercially. The reaction involves the reduction of chromuim(VI) in the orange dichromate ion, Cr2O72- to the green chromium(III) ion, Cr3+ by ethyl alcohol. 8H+ + Cr2O72- (orange) + 3C2H5OH ----> 2Cr3+ (green) + 3C2H4O + 7H2O FINAL CALL consists of a 10-cm glass tube packed with three bands of silica gel crystals coated with a dilute acidic solution of potassium dichromate to produce a yellow color. A test subject fills a balloon (included with the device) with breath; the filled balloon is attached to the end of the glass tube to allow the sampled breath to flow through the tube for 60 seconds. When ethyl alcohol vapor makes contact with the yellow-coated crystals, the color changes from yellow to green. The number of bands which change color and the intensity of the color indicate the relative amount of alcohol in the breath. To simulate the use of a FINAL CALL device, a few drops of ethyl alcohol are carefully placed in the end of the tube, followed by blowing through the tube. FINAL CALL is commonly used to monitor patients at alcohol-rehabilitation centers and in other situations where zero tolerance conditions exist (e.g., legal confinement and probation status).

  15. Analysis of organic sulfur and nitrogen in coal via tandem degradation methods. [Quarterly] technical report, March 1--May 31, 1993

    SciTech Connect

    Kruge, M.A.; Palmer, S.R.

    1993-09-01

    There is need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. In our research, we apply chemical and thermal degradation techniques to render coal amenable to standard gas chromatography characterization. Standard density gradient centrifugation successfully isolated vitrinite from the IBC101 coal, whereas the multi-step high resolution method was required to isolate liptinite and inertinite macerals, which are minority constituents. Analytical pyrolysis-gas chromatography, operating with either the sulfur selective flame photometric detector (py-GC-PFD) or a mass spectrometer (py-GC/MS), provides distinctive organosulfur ``fingerprints`` for all coal, asphaltene and maceral samples analyzed to date. PY-GC/MS permits ready differentiation of asphaltenes from low and high rank coals. Of the two pyrolysis techniques, py-GC-FPD is simpler and less expensive, and is the recommended method for situations in which sulfur content is the prime concern. Both py-GC methods are superior to oxidative degradation techniques in that they are permit direct, one-step micro-scale analysis, requiring only a minimum of sample preparation. Distinctive chromatographic profiles are also achieved using the methylated dichromate oxidation products of coals, asphaltenes and macerals, but the extensive wet chemical preparation required is a serious disadvantage. Reasonable matches for the expected masses of alkylthiophene carboxylic acid derivatives have been found in the direct probe, low voltage, high resolution mass spectral data set collected on the methylated dichromate oxidation products of the sulfur-rich Spanish lignite sample, providing an additional line of evidence confirming the presence of such compounds.

  16. Technical approaches of a natural dye extracted from Phytolacca americana L.-berries with chemical mordants.

    PubMed

    Park, Su-Youn; Jung, Suk-Yul

    2014-01-01

    Phytolacca americana L. is a large semi-succulent herbaceous plant which reaches three meters in height. It is native to eastern North America, the Midwest, and the Gulf Coast, with more scattered populations in the far West. It is imported into Korea and has been frequently used as a traditional natural drug for diseases such as systemic edema and nephritis. Its berries, that is, fruits are shiny dark purple held in racemous clusters on pink pedicels with a pink peduncle. They are round with a flat indented top and bottom. Immature berries are green, maturing into white and then blackish purple. It is not well known how the berries are used for a natural staining yet. In this study, using Phytolacca americana L.-berries, a natural staining was analyzed. Moreover, due to the broad use of chemical mordants, five different mordants including copper acetate, aluminum potassium sulfate, sodium tartrate plus citric acid, Iron II sulfate and potassium dichromate were combined. Extracted dye from the berries stained silk fabrics with ivory. The original purple color from the berries disappeared and transformed into ivory. Although the silk fabrics were differentially stained by the berries that were combined with mordants of aluminum potassium sulfate, sodium tartrate plus citric acid and potassium dichromate, only differences in lightness and darkness were observed. Interestingly, the combination of the dye from the berries with a mordant of copper acetate and Iron II sulfate induced the staining of the silk fabrics into khaki and dark khaki, respectively. This study is the first systemic report on staining silk fabrics with Phytolacca americana L.-berries and chemical mordants and suggests application of natural products to the fiber industry. PMID:24704646

  17. Groove binding mediated structural modulation and DNA cleavage by quinoline appended chalcone derivative.

    PubMed

    Kumar, Himank; Devaraji, Vinod; Prasath, Rangaraj; Jadhao, Manojkumar; Joshi, Ritika; Bhavana, Purushothaman; Ghosh, Sujit Kumar

    2015-12-01

    The present study embodies the detail DNA binding interaction of a potential bioactive quinoline appended chalcone derivative (E)-3-(anthracen-10-yl)-1-(6,8-dibromo-2-methylquinolin-3-yl)prop-2-en-1-one (ADMQ) with calf thymus DNA (ctDNA) and its consequences by UV-Vis absorption, steady state fluorescence spectroscopy, fluorescence anisotropy, circular dichromism, helix melting, agarose gel electrophoresis, molecular docking, Induced Fit Docking (IFD) and molecular dynamics (MD) simulation. The UV-Vis absorption and fluorescence study reveal that the molecule undergoes considerable interaction with the nucleic acid. The control KI quenching experiment shows the lesser accessibility of ADMQ molecule to the ionic quencher (I(-)) in presence of ctDNA as compared to the bulk aqueous phase. Insignificant change in helix melting temperature as well as in circular dichromism (CD) spectra points toward non-covalent groove binding interaction. The moderate rotational confinement of this chalcone derivative (anisotropy=0.106) trapped in the nucleic acid environment, the comparative displacement assay with well-known minor groove binder Hoechst 33258 and intercalator Ethidium Bromide establishes the minor groove binding interactions of the probe molecule. Molecular docking, IFD and MD simulation reveal that the DNA undergoes prominent morphological changes in terms of helix unwinding and bending to accommodate ADMQ in a crescent shape at an angle of 110° in a sequence specific manner. During interaction, ADMQ rigidifies and bends the sugar phosphate backbone of the nucleic acid and thereby shortens its overall length by 3.02Å. Agarose gel electrophoresis experiment with plasmid pBR 322 reveals that the groove binded ADMQ result in a concentration dependent cleavage of plasmid DNA into its supercoiled and nicked circular form. The consolidated spectroscopic research described herein provides quantitative insight into the interaction of a heterocyclic chalcone derivative

  18. Thermodynamically Guided Synthesis of Mixed-Linker Zr-MOFs with Enhanced Tunability.

    PubMed

    Yuan, Shuai; Qin, Jun-Sheng; Zou, Lanfang; Chen, Ying-Pin; Wang, Xuan; Zhang, Qiang; Zhou, Hong-Cai

    2016-05-25

    Guided by thermodynamics, we have synthesized two mixed-linker zirconium-based metal-organic frameworks (Zr-MOFs), namely, PCN-133 and PCN-134. Both of them possess a layer-pillar structure, in which the connection between Zr6 clusters and primary BTB linkers form a (3,6)-connected kdg layer that is further extended into 3D frameworks by auxiliary DCDPS/TCPP linkers (BTB = benzene tribenzoate, DCDPS = 4,4'-dicarboxydiphenyl sulfone, TCPP = tetrakis(4-carboxyphenyl)porphyrin). PCN-134 demonstrates high porosity (N2 uptake of 717 cm(3)·g(-1) and BET surface area of 1946 cm(2)·g(-1)) and excellent chemical stability in aqueous solutions with pH values ranging from 0 to 13. More importantly, PCN-134 tolerates the partial absence of auxiliary linkers leading to structural defects during the assembly process while preserving its framework integrity. Furthermore, the defect density can be systematically controlled by tuning the occupancy of the auxiliary linker, which in turn affects the MOF properties. For instance, the dichromate uptake of PCN-134 is tuned by adjusting the BTB/TCPP ratios, which gives rise to an efficient dichromate absorbent when the TCPP molar ratio in linkers is set as 22%. In addition, the photocatalytic reduction of Cr(VI) in aqueous solution was also performed by PCN-134-22%TCPP which exhibits excellent catalytic activity. This work not only opens up a new synthetic route toward mixed-linker MOFs, but also provides tunable control of MOF defects and, in turn, the properties. PMID:27151517

  19. Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules.

    PubMed

    Darwish, Ibrahim A; Khedr, Alaa S; Askal, Hassan F; Mohamed, Ramadan M

    2006-01-01

    Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia. PMID

  20. Black Carbon in Sedimentary Organic Carbon in the Northeast Pacific using the Benzene Polycarboxylic Acid Method

    NASA Astrophysics Data System (ADS)

    Coppola, A. I.; Ziolkowski, L. A.; Druffel, E. R.

    2010-12-01

    Black carbon (BC) in the Northeast Pacific ultrafiltered dissolved organic matter (UDOM) was found to be surprisingly old with a 14C age of 18,000 +/-3,000 14C years (Ziolkowski and Druffel, 2010) using the Benzene Polycarboxylic Acid (BPCA) method, while BC in sedimentary organic carbon (SOC) was found to be 2,400-12,900 14C years older than non-BC SOC (Masiello and Druffel, 1998) with a different method. Using the dichromate-sulfuric acid oxidation method (Wolbach and Anders, 1989), Masiello and Druffel (1998) estimated that 12-31% of SOC in the Northeast Pacific and the Southern Ocean surface sediments was black carbon (BC). However, the dichromate-sulfuric acid oxidation may over-estimate the concentration of BC, because this method is more biased toward modern (char) material (Currie et al., 2002). Alternatively, the BPCA method isolates aromatic components of BC as benzene rings substituted with carboxylic acid groups, and provides structural information about the BC. Recent modifications to the BPCA method by Ziolkowski and Druffel (2009) involve few biases in quantifying BC in the continuum between char and soot in UDOM. Here we use the BPCA method to determine the concentrations and 14C values of BC in sediments from three sites in the Northeast Pacific Ocean. Constraining the difference between non-BC SOC and BC-SOC using the BPCA method allows for a more precise estimate of how much BC is present in the sediments and its 14C age. Presumably, the intermediate reservoir of BC is oceanic dissolved organic carbon (DOC) and is, in part, responsible for DOC’s great 14C age. These results can be utilized to better constrain the oceanic carbon budget as a possible sink of BC. References: Currie, L. A., Benner Jr., B. A., Kessler, J.D., et al (2002), A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, nist srm 1649a, J. Res. Natl. Inst. Stand. Technol., 107, 279-298. Masiello, C

  1. Char BC amendments for soil and sediment amelioration: BC quantification and field pilot trials

    NASA Astrophysics Data System (ADS)

    Cornelissen, G.; Braendli, R. C.; Eek, E.; Henriksen, T.; Hartnik, T.; Breedveld, G. D.

    2008-12-01

    Background Activated char BC binds organic contaminants and possibly mercury so strongly that their bioaccumulation and transport to other environmental compartments are reduced. The advantages of black carbon amendment over many other remediation methods include i) it can be used as an in situ risk reduction method, ii) the price is low, and iii) it overcomes significant controversies associated with disposal of dredged and excavated materials. In this study BC amendment is used in pilot trials in the field for soil and sediment amelioration. Quantification of amended char BC Two methods for char BC quantification were tested: i) chemothermal oxidation (CTO) at a range of temperatures and ii) wet chemical oxidation with a potassium dichromate/sulfuric acid solution. The amount of BC amended to three soils was accurately determined by CTO at 375°C. For two sediments, much of the BC disappeared during combustion at 375°C, which could probably be explained by catalytic effects caused by sediment constituents such as metals, mineral oxides and salts. Attempts to avoid these effects through rinsing with acid before combustion did not result in higher char BC recoveries. CTO at lower temperatures (325-350°C) was a feasible alternative for one of the sediments. Wet oxidation with potassium dichromate/sulfuric acid proved to effectively function for BC quantification in sediments, since almost complete BC recovery (81-92 %) was observed for both sediments, while the amount of organic carbon remaining was low (5-16 %). Field pilots Earlier, we showed the effectiveness of BC amendment in the laboratory. In the laboratory it was shown that BC amendments (2 %) reduced freely dissolved porewater concentrations (factor of 10-50) and bioaccumulation (factor of 5). This presentation will describe 50 × 50 m pilot field trials in Norway (2007-2008): Trondheim Harbor (sediment) and Drammen (soil). The presentation will focus on physical monitoring (distribution of BC in the

  2. Effect of storage media, temperature, and time on preservation of Cryptosporidium parvum oocysts for PCR analysis.

    PubMed

    Lalonde, L F; Gajadhar, A A

    2009-03-23

    The effect of storage media, temperature, and time on suitability of oocysts for use in subsequent molecular studies was examined. Cryptosporidium parvum oocysts were stored for 3, 6, 9, or 12 months in sterile dH(2)O, 70 or 95% ethanol, (room temperature [RT], 4, -20, and -70 degrees C), 10% formalin (RT and 4 degrees C), PBS, TE buffer, antibiotic-antimycotic (A-A) solution (4, -20 and -70 degrees C), 2% sulphuric acid, 2.5% potassium dichromate (4 degrees C), and gDNA from 10(4) oocysts was extracted in triplicate and subjected to PCR. To determine the effect of storage media on PCR sensitivity, gDNA from 10(4), 10(2), and 10(0) oocysts stored for 15 months in the media listed above at RT or 4 degrees C was also extracted in triplicate and subjected to PCR. At RT, ethanol was suitable for up to 15 months, while gDNA from oocysts stored in dH(2)O amplified inconsistently after 3 months. At 4 degrees C, all tested media except dH(2)O and formalin were suitable for storage of 10(4) oocysts up to 15 months, but only 70% ethanol, A-A solution, 2% sulphuric acid and 2.5% potassium dichromate supported amplification of gDNA from fewer than 100 oocysts. At -20 degrees C, 95% ethanol, PBS, or TE were suitable for up to 9 months, while 70% ethanol and A-A solution were effective up to 12 months, and gDNA from oocysts stored in dH(2)O was inconsistently amplified after 6 months. Storage at -70 degrees C for up to 12 months was effective regardless of media type. Oocysts stored in formalin at RT or 4 degrees C could not be amplified by PCR despite washing prior to gDNA extraction. To maintain gDNA quality suitable for PCR, it is recommended that coccidian oocysts be stored at -70 degrees C in dH(2)O, ethanol, PBS, TE or A-A solution, at 4 degrees C in A-A or ethanol, or at RT in ethanol where refrigerated storage is unavailable. PMID:19128883

  3. Efficiencies and Optimization of Weak Base Anion Ion-Exchange Resin for Groundwater Hexavalent Chromium Removal at Hanford

    SciTech Connect

    Nesham, Dean O.; Ivarson, Kristine A.; Hanson, James P.; Miller, Charles W.; Meyers, P.; Jaschke, Naomi M.

    2014-02-03

    The U.S. Department of Energy’s (DOE’s) contractor, CH2M HILL Plateau Remediation Company, has successfully converted a series of groundwater treatment facilities to use a new treatment resin that is delivering more than $3 million in annual cost savings and efficiency in treating groundwater contamination at the DOE Hanford Site in southeastern Washington State. During the production era, the nuclear reactors at the Hanford Site required a continuous supply of high-quality cooling water during operations. Cooling water consumption ranged from about 151,417 to 378,541 L/min (40,000 to 100,000 gal/min) per reactor, depending on specific operating conditions. Water from the Columbia River was filtered and treated chemically prior to use as cooling water, including the addition of sodium dichromate as a corrosion inhibitor. Hexavalent chromium was the primary component of the sodium dichromate and was introduced into the groundwater at the Hanford Site as a result of planned and unplanned discharges from the reactors starting in 1944. Groundwater contamination by hexavalent chromium and other contaminants related to nuclear reactor operations resulted in the need for groundwater remedial actions within the Hanford Site reactor areas. Beginning in 1995, groundwater treatment methods were evaluated, leading to the use of pump-and-treat facilities with ion exchange using Dowex™ 21K, a regenerable, strong-base anion exchange resin. This required regeneration of the resin, which was performed offsite. In 2008, DOE recognized that regulatory agreements would require significant expansion for the groundwater chromium treatment capacity. As a result, CH2M HILL performed testing at the Hanford Site in 2009 and 2010 to demonstrate resin performance in the specific groundwater chemistry at different waste sites. The testing demonstrated that a weak-base anion, single-use resin, specifically ResinTech SIR-700 ®, was effective at removing chromium, had a significantly

  4. Black carbon contribution to stabilised SOM in soil under slash and burn agriculture

    NASA Astrophysics Data System (ADS)

    Rumpel, C.; Chaplot, V.; Valentin, C.

    2008-12-01

    Black carbon (BC) produced during slash and burn agriculture on tropical soils may enhance the soils organic matter content and hence their biological properties. However, once deposited on the soil surface, BC may be subject to erosion and/or microbial decomposition and thus not be preserved on site. Up to now, few studies have been carried out to assess the contribution of BC to the soils stable carbon pool on sites under slash and burn agriculture. The aim of the study was to assess the survival potential of BC in sloping tropical soils of clayey texture. The study was carried out in Northern Laos, where the soils are subjected to addition of black carbon produced by burning of agricultural crop residues. Our conceptual approach included the characterisation of (a) morphologically distinct BC forms and (b) chemical soil fractions. The samples were analysed for elemental content, chemical composition by 13C CPMAS NMR spectroscopy, carbon resistant to acid hydrolysis with HCl, carbon resistant to oxidation with acid dichromate solution and 14C activity. Our results indicated that BC produced by slash and burn agriculture was highly aromatic in nature. Its elemental composition as well as its susceptibility to be lost by chemical oxidation was dependent on its morphology. Acid hydrolysis did not lead to carbon loss from any BC form. We thus hypothesised that BC should be present in the hydrolysis resistant fraction isolated from soil. The charactersation of the chemical composition by 13C CPMAS NMR spectroscopy showed that the hydrolysis residue was composed of highly aromatic carbon. Considering the low lignin content of these soils and the good recovery of bulk soil aromatic carbon signal (80-100%) in the hydrolysis residue, we consider that this fraction may be suitable to assess BC contribution to clayey soils. We suggest that BC isolated as hydrolysis resistant C may represent up to 25% of the soils C as compared to 8% as isolated by acid dichromate oxidation

  5. Design and manufacture of transmission volume phase holographic grating used in VIS/NIR wave band

    NASA Astrophysics Data System (ADS)

    Fang, Chunhuan; Tang, Minxue; Wu, Jianhong

    2011-11-01

    Due to its uniform dispersion and higher diffraction efficiency, transmission volume phase holographic grating (VPHG) has been widely used for astronomical spectroscopy, ultrafast lasers compressors and wavelength division multiplexers. According to its application requirement and based on the Rigorous Coupled Wave Analysis (RCWA), a transmission VPHG with a frequency of 196lp/mm is designed and manufactured in this paper. The thickness of gelatin and the modulation of refraction index are optimized for high diffraction efficiency over a wavelength range from 420nm to 1000nm. The grating was recorded in dichromate gelatin (DCG) and in a symmetrical light path. By controlling the coating, exposure and post-processing conditions, the thickness of gelatin and the modulation of refraction index can be adjusted. The diffraction efficiency varied within the required wave band and the polarization property of the illumination wave were measured and compared with that of the theoretical ones. From the results, it can be seen that by adjusting and controlling the preparation conditions of DCG plates, the exposure value and post-processing technique, the peak diffraction efficiency of VPHG reaches to 47% and the average diffraction efficiency is above 35% in the spectral coverage, which is close to the theoretical values. This transmission VPHG can be applied in a prism-grating-prism (PGP) imaging spectrometer.

  6. Optimization of a histopathological biomarker for sphingomyelin accumulation in acid sphingomyelinase deficiency.

    PubMed

    Taksir, Tatyana V; Johnson, Jennifer; Maloney, Colleen L; Yandl, Emily; Griffiths, Denise; Thurberg, Beth L; Ryan, Susan

    2012-08-01

    Niemann-Pick disease (types A and B), or acid sphingomyelinase deficiency, is an inherited deficiency of acid sphingomyelinase, resulting in intralysosomal accumulation of sphingomyelin in cells throughout the body, particularly within those of the reticuloendothelial system. These cellular changes result in hepatosplenomegaly and pulmonary infiltrates in humans. A knockout mouse model mimics many elements of human ASMD and is useful for studying disease histopathology. However, traditional formalin-fixation and paraffin embedding of ASMD tissues dissolves sphingomyelin, resulting in tissues with a foamy cell appearance, making quantitative analysis of the substrate difficult. To optimize substrate fixation and staining, a modified osmium tetroxide and potassium dichromate postfixation method was developed to preserve sphingomyelin in epon-araldite embedded tissue and pulmonary cytology specimens. After processing, semi-thin sections were incubated with tannic acid solution followed by staining with toluidine blue/borax. This modified method provides excellent preservation and staining contrast of sphingomyelin with other cell structures. The resulting high-resolution light microscopy sections permit digital quantification of sphingomyelin in light microscopic fields. A lysenin affinity stain for sphingomyelin was also developed for use on these semi-thin epon sections. Finally, ultrathin serial sections can be cut from these same tissue blocks and stained for ultrastructural examination by electron microscopy. PMID:22614361

  7. PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM

    DOEpatents

    Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

    1959-11-10

    Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

  8. Detection of Emergence Cyclospora cayetanensis in A HIV+ / AIDS Patient with Diarrhea from Tehran: A Case Report

    PubMed Central

    KHANALIHA, Khadijeh; MOHEBALI, Mehdi; DAVOUDI, Setareh; REZA HOSSEINI, Omid; TARIGHI, Fatemeh; REZAEIAN, Tahereh; REZAEIAN, Mostafa

    2015-01-01

    Coccidian protozoa of Cyclospora cayetanensis are obligate intracellular apicomplexan parasites that infect the mucosal epithelium of the small intestine of immunocompetent and immunocompromised persons. A 25- years old woman from around, Tehran with complaint of faintness and fatigue with HIV positive/AIDS confirmed eight months ago was admitted in Imam Khomeini Hospital, Tehran, Iran in 2014. The patient suffered from intestinal and lung symptoms like watery diarrhea, flu-like symptoms. The stool was examined by direct preparation and concentration technique, stained with modified acid-fast staining method, and observed with light and then Immunofluorescence microscope. The stool cultivation was made in dichromate potassium medium and diagnosis of Cyclospora infection was finally made according to observation of Cyclospora oocysts almost 10 μm in acid-fast staining method and autofluorescence of Cyclospora under Immunofluorescence microscope. The patient was initially treated with azithromycin, tazocin and fluconazol because of lung lesions and diarrhea and relative remission was observed. Cyclospora sp. causes an intestinal infection particularly in immunocompromised patients. PMID:26258100

  9. The protective effect of propylthiouracil against hepatotoxicity induced by chromium in adult mice.

    PubMed

    Ben Hamida, Fatma; Troudi, Afef; Sefi, Madiha; Boudawara, Tahia; Zeghal, Najiba

    2016-02-01

    Environmental and occupational exposure to chromium compounds, especially hexavalent chromium (Cr(VI)), is widely recognized as potentially hepatotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. This study focused on the possible protective effect of propylthiouracil (PTU) against potassium dichromate (K2Cr2O7). Female mice were divided into four groups (groups I-IV) with seven animals in each group. Group I served as a control, which received tap water; group II received K2Cr2O7 alone (75 mg kg(-1) body weight (b.w.)) via drinking water; group III received both K2Cr2O7 via drinking water and PTU by intramuscular injection at a dose 2.5 mg/100 g(-1) b.w. twice a week, and group IV received PTU alone twice a week for 30 days. Exposure of mice to Cr promoted oxidative stress with an increase in malondialdehyde, protein carbonyl, and advanced oxidation protein product levels. Nonenzymatic antioxidants such as glutathione, nonprotein thiol, vitamin C levels and enzymatic antioxidant activities such as glutathione peroxidase and superoxide dismutase were decreased, while catalase activity was increased. Biomarkers of liver injury such as aspartate and alanine transaminases, lactate dehydrogenase activities, bilirubin, albumin, and glucose levels were increased, while triglyceride and cholesterol levels decreased. Coadministration of PTU restored the above-mentioned parameters to near-normal values. The histological findings confirmed the biochemical results. PMID:24081637

  10. Unraveling the mechanism responsible for the contrasting tolerance of Synechocystis and Synechococcus to Cr(VI): Enzymatic and non-enzymatic antioxidants.

    PubMed

    Gupta, Alka; Ballal, Anand

    2015-07-01

    Two unicellular cyanobacteria, Synechocystis and Synechococcus, showed contrasting tolerance to Cr(VI); with Synechococcus being 12-fold more tolerant than Synechocystis to potassium dichromate. The mechanism responsible for this differential sensitivity to Cr(VI) was explored in this study. Total content of photosynthetic pigments as well as photosynthetic activity decreased at lower concentration of Cr(VI) in Synechocystis as compared to Synechococcus. Experiments with (51)Cr showed Cr to accumulate intracellularly in both the cyanobacteria. At lower concentrations, Cr(VI) caused excessive ROS generation in Synechocystis as compared to that observed in Synechococcus. Intrinsic levels of enzymatic antioxidants, i.e., superoxide dismutase, catalase and 2-Cys-peroxiredoxin were considerably higher in Synechococcus than Synechocystis. Content of total thiols (both protein as well as non-protein) and reduced glutathione (GSH) was also higher in Synechococcus as compared to Synechocystis. This correlated well with higher content of carbonylated proteins observed in Synechocystis than Synechococcus. Additionally, in contrast to Synechocystis, Synechococcus exhibited better tolerance to other oxidative stresses like high intensity light and H2O2. The data indicate that the disparity in the ability to detoxify ROS could be the primary mechanism responsible for the differential tolerance of these cyanobacteria to Cr(VI). PMID:25956322

  11. Decolorization of Distillery Spent Wash Using Biopolymer Synthesized by Pseudomonas aeruginosa Isolated from Tannery Effluent

    PubMed Central

    David, Charles; Arivazhagan, M.; Balamurali, M. N.; Shanmugarajan, Dhivya

    2015-01-01

    A bacterial strain was isolated from tannery effluent which can tolerate high concentrations of potassium dichromate up to 1000 ppm. The isolated microorganism was identified as Pseudomonas aeruginosa by performing biochemical tests and molecular characterization. In the presence of excess of carbohydrate source, which is a physiological stress, this strain produces Polyhydroxybutyrate (PHB). This intracellular polymer, which is synthesized, is primarily a product of carbon assimilation and is employed by microorganisms as an energy storage molecule to be metabolized when other common energy sources are limitedly available. Efforts were taken to check whether the PHB has any positive effect on spent wash decolorization. When a combination of PHB and the isolated bacterial culture was added to spent wash, a maximum color removal of 92.77% was found which was comparatively higher than the color removed when the spent wash was treated individually with the PHB and Pseudomonas aeruginosa. PHB behaved as a support material for the bacteria to bind to it and thus develops biofilm, which is one of the natural physiological growth forms of microorganisms. The bacterial growth in the biofilm and the polymer together acted in synergy, adsorbing and coagulating the pollutants in the form of color pigments. PMID:26504787

  12. A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters.

    PubMed

    Zhang, Shanqing; Li, Lihong; Zhao, Huijun

    2009-10-15

    A photoelectrochemical probe for rapid determination of chemical oxygen demand (COD) is developed using a nanostructured mixed-phase TiO2 photoanode, namely PeCOD probe. A UV-LED light source and a USB mircroelectrochemical station are powered and controlled by a laptop computer, which makes the probe portable for onsite COD analyses. The photoelectrochemical measurement of COD was optimized in terms of light intensity, applied bias, and pH. Under the optimized conditions, the net steady state currents originated from the oxidation of organic compounds were found to be directly proportional to COD concentrations. A practical detection limit of 0.2 ppm COD and a linear range of 0-120 ppm COD were achieved. The analytical method using the portable PeCOD probe has the advantages of being rapid, low cost, robust, user-friendly, and environmental friendly. It has been successfully applied to determine the COD values of the synthetic samples consisting of potassium hydrogen phthalate, D-glucose, glutamic acid, glutaric acid, succinic acid, and malonic acid, and real samples from various industries, such as bakery, oil and grease manufacturer, poultry, hotel, fine food factory, and fresh food producer, commercial bread manufacturer. Excellent agreement between the proposed method and the conventional COD method (dichromate) was achieved. PMID:19921898

  13. Toward the complete utilization of rice straw: Methane fermentation and lignin recovery by a combinational process involving mechanical milling, supporting material and nanofiltration.

    PubMed

    Sasaki, Kengo; Okamoto, Mami; Shirai, Tomokazu; Tsuge, Yota; Fujino, Ayami; Sasaki, Daisuke; Morita, Masahiko; Matsuda, Fumio; Kikuchi, Jun; Kondo, Akihiko

    2016-09-01

    Rice straw was mechanically milled using a process consuming 1.9MJ/kg-biomass, and 10g/L of unmilled or milled rice straw was used as the carbon source for methane fermentation in a digester containing carbon fiber textile as the supporting material. Milling increased methane production from 226 to 419mL/L/day at an organic loading rate of 2180mg-dichromate chemical oxygen demand/L/day, corresponding to 260mLCH4/gVS. Storage of the fermentation effluent at room temperature decreased the weight of the milled rice straw residue from 3.81 to 1.00g/L. The supernatant of the effluent was subjected to nanofiltration. The black concentrates deposited on the nanofiltration membranes contained 53.0-57.9% lignin. Solution nuclear magnetic resonance showed that lignin aromatic components such as p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) were retained primarily, and major lignin interunit structures such as the β-O-4-H/G unit were absent. This combinational process will aid the complete utilization of rice straw. PMID:27318161

  14. Diversity of Eimeria spp. in dairy cattle of Guwahati, Assam, India

    PubMed Central

    Das, M.; Deka, D. K.; Sarmah, P. C.; Islam, S.; Sarma, S.

    2015-01-01

    Aim: To determine the prevalence and diversity of Eimeria spp. in dairy cattle present in and around Guwahati, Kamrup district, Assam, India. Materials and Methods: A total of 2339 fecal samples of calves (535), heifer (641) and adult (1163) cattle were screened for 1 year present in and around Guwahati, Assam for detection of Eimeria oocysts by flotation techniques. Sporulation of the oocyst was done in 2.5% potassium dichromate solution for identification of the Eimeria species. Results: Examination of fecal samples revealed an overall prevalence of 11.97% Eimeria infection in dairy cattle of Guwahati, Assam. Age-wise, 33.2%, 45.4%, and 21.4% infections were recorded in calves (<1 year), heifer (1-3 years) and adult (>3 years) cattle, respectively. Season-wise, infection was recorded highest during post-monsoon (16.29%), followed by monsoon (15%), winter (9.44%), and pre-monsoon (7.49%) season. Seven species of Eimeria were recorded viz. Eimeria bovis, Eimeria zuernii, Eimeria subspherica, Eimeria bukidnonensis, Eimeria auburnensis, Eimeria ellipsoidalis and Eimeria alabamensis. The oocyst count per gram of feces ranged from 50 to 1500 in infected cattle. Conclusion: This study indicates that there is the prevalence of seven species of Eimeria in dairy cattle of Guwahati, Assam and mostly prevalent during the post-monsoon season. PMID:27047181

  15. Reduction of Cr(VI) to Cr(III) using silicon nanowire arrays under visible light irradiation.

    PubMed

    Fellahi, Ouarda; Barras, Alexandre; Pan, Guo-Hui; Coffinier, Yannick; Hadjersi, Toufik; Maamache, Mustapha; Szunerits, Sabine; Boukherroub, Rabah

    2016-03-01

    We report an efficient visible light-induced reduction of hexavalent chromium Cr(VI) to trivalent Cr(III) by direct illumination of an aqueous solution of potassium dichromate (K2Cr2O7) in the presence of hydrogenated silicon nanowires (H-SiNWs) or silicon nanowires decorated with copper nanoparticles (Cu NPs-SiNWs) as photocatalyst. The SiNW arrays investigated in this study were prepared by chemical etching of crystalline silicon in HF/AgNO3 aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K2Cr2O7 (10(-4)M) in presence of H-SiNWs showed that these substrates were not efficient for Cr(VI) reduction. The reduction efficiency achieved was less than 10% after 120 min irradiation at λ>420 nm. Addition of organic acids such as citric or adipic acid in the solution accelerated Cr(VI) reduction in a concentration-dependent manner. Interestingly, Cu NPs-SiNWs was found to be a very efficient interface for the reduction of Cr(VI) to Cr(III) in absence of organic acids. Almost a full reduction of Cr(VI) was achieved by direct visible light irradiation for 140 min using this photocatalyst. PMID:26610097

  16. Journey through Bui-Bui

    NASA Astrophysics Data System (ADS)

    MacArthur, Ana C.

    2000-10-01

    In a continuation of my search for an understanding of sunlight's relationship to the health of the human organism, I created the installation A Journey Through Bui-Bui; Lifting the Purdah of Mal-Illumination. It was exhibited in 1999 at The Museum of Fine Arts, Santa Fe, New Mexico. The entire work pivots around the image of the veil worn by Muslim women, as both content and metaphor related to the issue of the absence or presence of light in the physical body. The following paper will discuss the development of concepts and the technical progression of this recently completed large-scale mixed media work. This three-roomed installation integrated life casts of the human figure covered in veils, various sculptural elements, fiber optics, and dichromated gelatin (DCG) holograms. The DCG holographic glass objects were produced with an array of glass sculpting tools. I will also briefly discuss current work evolving out of this installation, which further explored the sculptural possibilities of glass and the coating and recording of DCG on curved surfaces.

  17. In situ Carica papaya stem matrix and Fusarium oxysporum (NCBT-156) mediated bioremediation of chromium.

    PubMed

    Amatussalam, A; Abubacker, M N; Rajendran, R Babu

    2011-12-01

    Removal of heavy metal chromium was carried out using the fungus Fusarium oxysporum NCBT-156 strain isolated from soil of leather tanning effluent in in situ condition using potassium dichromate solution with 10 per cent Czapek-dox liquid medium. Biosorbent matrix was developed using Carica papaya plant dry stem to colonize the fungal strain to facilitate bioabsorption process. Bioabsorption of chromium was by metabolically mediated intracellular accumulation process. Maximum efficiency of chromium removal by biosorption upto 90 per cent was achieved at the end of 5th day of incubation (120 h of contact time) for 100 and 200 ppm concentration, upto 80 per cent for 300 and 400 ppm, and upto 65 per cent for 500 ppm to 1000 ppm concentrations with pH ranging from 5.8, 5.6, 5.5, 5.4 and 5.2, respectively for 100, 200, 300, 400, 500-1000 ppm concentration. SDS-PAGE protein profile showed significant difference in 34 kDa protein band after chromium absorption by the fungus. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of chromium by F. oxysporium strain were carbonyl, carboxyl, amino and hydroxyl groups. PMID:22403866

  18. Structural and spectroscopic characterization of the macrocyclic complex: [Tb(CrO{sub 4})(H{sub 2}O)(C{sub 22}H{sub 26}N{sub 6})] {center_dot}0.5(Cr{sub 2}O{sub 7}){center_dot}(H{sub 2}O)

    SciTech Connect

    Ayala, J.D.; Bombieri, G.; Benetollo, F.

    1995-06-01

    The title complex was obtained by anion metathesis form [Tb(CH{sub 3}COO){sub 2}(C{sub 22}H{sub 26}N{sub 6})] (CH{sub 3}COO){center_dot}4H{sub 2}O and K{sub 2}CrO{sub 4} in aqueous solution. The compound crystallizes in the triclinic space group P1 with a = 8.384(2), b = 10.425(2) c = 15.752(2){angstrom}, {alpha} = 98.82(2), {beta} = 93.52(2), {gamma} = 97.22(2){degrees}, and Z = 2. The structure is ionic and consists of a (+1) complex cation balanced in a 2:1 ratio by a disordered dichromate ion. The 9-coordinate Tb(III) is linked to the six nitrogen atoms of the macrocyclic ligand L = C{sub 22}H{sub 26}N{sub 6}, as well as to a water molecule and a bidentate chelating chromate situated on opposite sides of the macrocycle. The infrared spectrum shows, in addition to the pattern of the macrocyclic ligand, the absorptions arising form the stretching modes of the bidentate chelating CrO{sub 4}{sup 2{minus}} ligand and of the Cr{sub 2}O{sub 7}{sup 2{minus}} counterion.

  19. Corrosion behavior of brass alloys in aqueous solutions of different pH

    SciTech Connect

    Badawy, W.A.; Al-Kharafi, F.M.

    1999-03-01

    Corrosion and passivation behaviors of three brass alloys, including selective leaching of the alloys in acidic, neutral, and basic solutions, were investigated in aqueous solutions of different pH. Open-circuit potential measurements, polarization data, and electrochemical impedance spectroscopy (EIS) were used to obtain the corrosion current density, corrosion potential, and corrosion resistance of each alloy. results, especially for open-circuit potential behavior, were compared to those of the pure alloy constituents (i.e., copper, lead, and zinc). In aqueous solutions, the alloy surface was covered by a passive Cu(I) film, which was responsible for the passive behavior of the surface. The stability of such a passive film was dependent upon the solution pH and was affected by alloy composition. The presence of oxygen (O{sub 2}) or oxidizers such as dichromate (Cr{sub 2}O{sub 7}{sup 2{minus}}) in the solution or the increased ratio of active component in the alloy enhanced the disproportionation reactions, which led to breakdown of the passive film, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to explain and to confirm polarization and EIS results. A mechanism for the reactions taking place at the electrode/electrolyte interface was suggested.

  20. Rapid Determination of the Chemical Oxygen Demand of Water Using a Thermal Biosensor

    PubMed Central

    Yao, Na; Wang, Jinqi; Zhou, Yikai

    2014-01-01

    In this paper we describe a thermal biosensor with a flow injection analysis system for the determination of the chemical oxygen demand (COD) of water samples. Glucose solutions of different concentrations and actual water samples were tested, and their COD values were determined by measuring the heat generated when the samples passed through a column containing periodic acid. The biosensor exhibited a large linear range (5 to 3000 mg/L) and a low detection limit (1.84 mg/L). It could tolerate the presence of chloride ions in concentrations of 0.015 M without requiring a masking agent. The sensor was successfully used for detecting the COD values of actual samples. The COD values of water samples from various sources were correlated with those obtained by the standard dichromate method; the linear regression coefficient was found to be 0.996. The sensor is environmentally friendly, economical, and highly stable, and exhibits good reproducibility and accuracy. In addition, its response time is short, and there is no danger of hazardous emissions or external contamination. Finally, the samples to be tested do not have to be pretreated. These results suggest that the biosensor is suitable for the continuous monitoring of the COD values of actual wastewater samples. PMID:24915178

  1. First report of birds infection by intestinal parasites in Khorramabad, west Iran.

    PubMed

    Badparva, Ebrahim; Ezatpour, Behrouz; Azami, Mehdi; Badparva, Masoud

    2015-12-01

    Parasitic infections in birds are omnipresent, even when they occur in low amounts, may result in subclinical diseases. There aren't any studies, based on Iranian data, investigating the prevalence of intestinal parasitic infections in some birds' species. We conducted a cross-sectional study between December 2011 and December 2012. The fecal samples were taken from 451 birds including hen, turkey, sparrow, pigeon and decorative birds. The samples screened for intestinal parasitic infections using direct smear, formalin-ether concentration technique, modified Ziehl-Neelsen staining, Culture in RPMI 1640 medium, sporulation with potassium dichromate and Trichrome and Giemsa staining. Out of 451 birds' species, 157 (34.8 %), were infected with one or more type of intestinal parasites. We identified two nematode, two cestoda species and five protozoan parasites species. No trematodes were found in the samples studied. The parasites identified among birds involved Raillietina spp. (4.2 %) and Eimeria spp. (7.1 %) were the most common helminthes and protozoa respectively. From total of birds study, 12 (2.7 %) and 6 (1.3 %) have two and three mixed infections respectively. Intestinal parasitic infections are common in birds in west Iran. The future studies are needed in order to determine to which extent the infections influence mortality and performance of the birds. PMID:26688641

  2. Acute effects of hexavalent chromium on survival, oxygen consumption, hematological parameters and some biochemical profiles of the Indian major carp, Labeo rohita.

    PubMed

    Vutukuru, S S

    2005-12-01

    An attempt has been made in the present investigation to determine the acute toxicity of hexavalent chromium and its toxicological effects on survival, physiological, hematological and biochemical parameters of the widely consumed Indian major carp, Labeo rohita. Short-term acute toxicity tests were performed adopting renewal bioassay technique (USEPA, 1975) over a period of 96 h, using different concentrations of potassium dichromate to the fish and the 96 h LC[50] value was found to be 111.45 mg/l (Cr(+6) as 39.40 mg/l). ANOVA results showed that the normal respiratory activity of the fish was significantly affected and there is a depression in the metabolic rate at the end of 24, 48, 72 and 96 h exposure. The metal also induced significant decrease (p<0.001) in the hematological parameters of the fish like total erythrocyte count, hemoglobin percent and absolute value Mean cell hemoglobin (MCH) both at the end of 24h and 96 h exposure indicating anemia. Appreciable decline in the biochemical profiles such as total glycogen, total lipids and total protein contents of the fish was also observed. However, the decrease in protein content was significant only at the end of 96 h. This study reflects the extent of the toxic effects of hexavalent chromium and the metal induced cumulative deleterious effects at various functional levels in the widely consumed freshwater fish, Labeo rohita. PMID:16819101

  3. Molecular design and synthesis of 3-oxocyclohexyl methacrylate for ArF and KrF excimer laser resist

    SciTech Connect

    Kozaki, Koji; Kaimoto, Yuko; Takahashi, Makoto

    1994-09-01

    The authors originally designed 3-oxocyclohexyl methacrylate (OCMA) for an acid-labile component in chemical amplification. The key concept of the molecular design of the 3-oxocyclohexyl substituent was the introduction of acidic protons at the {alpha}-position of the elimination site by using a ketone functional group. OCMA was synthesized by esterification of 1,3-cyclohexanediol and methacryloyl chloride followed by pyridinium dichromate oxidation. Using AIBN as an initiator, the authors also prepared poly(OCMA-co-AdMA) (AdMA: adamantyl methacrylate) by a thermally induced radical copolymerization of OCMA and AdMA. The resist comprises the copolymer and 10 wt % of triphenylsulfonium hexafluoroantimonate as a photoacid generator (PAG). This resist has high sensitivity, good thermal stability, good dry etch resistance, and good postexposure delay durability. Using a KrF excimer laser stepper (NA = 0.45) and 2-propanol mixed aqueous alkali developer, the authors obtained 0.3-{mu}m line and space patterns with this resist. A resist with 1 wt % of the PAG has an acceptable transmittance at 193 nm, proving that this resist is suitable for ArF excimer lithography. 29 refs., 10 figs., 2 tabs.

  4. Flow injection method for the rapid determination of chemical oxygen demand based on microwave digestion and chromium speciation in flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Cuesta, A.; Todoli, J. L.; Canals, A.

    1996-12-01

    The present paper describes a new flow injection method for the determination of Chemical Oxygen Demand (COD). This method consists of a first digestion step, where the sample is heated by microwave radiation, a second one where an anionic exchange resin retains the Cr(VI) that has not been reduced by the organic matter of the sample and a third one where Cr(VI), after being eluted, is determined by flame atomic absorption spectrometry. The microwave power applied, the sulphuric acid concentration, the liquid flow in the digestion step and the sample volume were the variables studied. The recovery and precision obtained with this method are similar to those obtained using a standard semi-micro method, whereas the throughput is much higher (up to 50 determinations per hour). As regards sensitivity, by changing the sample loop volume and the concentration of dichromate, one can analyze samples with Chemical Oxygen Demand values between 25 and 5000 mg/l. The limit of detection is about 7 mg/l COD. An interesting feature of the new method, which is not shared by most other flow injection methods of Chemical Oxygen Demand determination, is that there is no matrix effect in the determination step.

  5. Remediation of chromium-slag leakage with electricity cogeneration via a urea-Cr(VI) cell

    PubMed Central

    Yu, Binbin; Zhang, Huimin; Xu, Wei; Li, Gang; Wu, Zucheng

    2014-01-01

    Chromium pollution has been historically widespread throughout the world. Most available remediation technologies often require energy consumption. This study is aimed to develop electrochemical remediation for Cr(VI) in chromium-slag leakage with self-generated electricity. Dynamic leaching experiments of chromium-slag samples were conducted to survey the release and leaching behavior of Cr(VI). Based on previous work, a unique urea-Cr(VI) was designed, in which urea was employed as the fuel and Cr(VI) from the leakage of the dichromate slag served as the oxidant. Furthermore, the electrochemical results showed that the removal percent of Cr(VI) was more than 96% after 18 h with the leakage Cr(VI) concentration of 2.69 mM. The open circuit potential (OCP) varied in the range of 1.56 ~ 1.59 V under different initial Cr(VI) leakage concentrations. The approach explores the feasibility of the promising technique without the need of energy input for simultaneous chromium-slag remediation and generation of electricity. PMID:25168513

  6. Biotransformation of phosphogypsum in wastewaters from the dairy industry.

    PubMed

    Wolicka, Dorota

    2008-09-01

    The biotransformation of phosphogypsum by stationary cultures of sulphate reducing bacteria (SRB) in dairy wastewaters (sterile and non-sterile) enriched in phosphogypsum, was studied SRB were isolated from soil contaminated with petroleum-derived products and from wastewaters from the petroleum-refining industry, taking into account that these environments are characteristic for the bacteria of the studied group. The biotransformation products formed were investigated using biological and mineralogical methods. Sulphides in the cultures were determined using the iodometric method, sulphates with the hot barium method, COD by the dichromate method. Determinations involving post-culture sediments and fluids, Ca, S, Sr and P were made using the following analytical procedures: IPC emission spectrometry with induced excitation in the medium and X-ray. Analysis of post-culture sediments was made using a DRON-2 X-ray diffractometer. Eleven communities of microorganisms with varying degrees of effectiveness were obtained, biodegrading 58% to 98% of the organic contaminants in non-sterile wastewater, with simultaneous biotransformation of about 2.5 g phosphogypsum/L. PMID:18061442

  7. Isolation of Cellulose-Degrading Bacteria and Determination of Their Cellulolytic Potential

    PubMed Central

    Gupta, Pratima; Samant, Kalpana; Sahu, Avinash

    2012-01-01

    Eight isolates of cellulose-degrading bacteria (CDB) were isolated from four different invertebrates (termite, snail, caterpillar, and bookworm) by enriching the basal culture medium with filter paper as substrate for cellulose degradation. To indicate the cellulase activity of the organisms, diameter of clear zone around the colony and hydrolytic value on cellulose Congo Red agar media were measured. CDB 8 and CDB 10 exhibited the maximum zone of clearance around the colony with diameter of 45 and 50 mm and with the hydrolytic value of 9 and 9.8, respectively. The enzyme assays for two enzymes, filter paper cellulase (FPC), and cellulase (endoglucanase), were examined by methods recommended by the International Union of Pure and Applied Chemistry (IUPAC). The extracellular cellulase activities ranged from 0.012 to 0.196 IU/mL for FPC and 0.162 to 0.400 IU/mL for endoglucanase assay. All the cultures were also further tested for their capacity to degrade filter paper by gravimetric method. The maximum filter paper degradation percentage was estimated to be 65.7 for CDB 8. Selected bacterial isolates CDB 2, 7, 8, and 10 were co-cultured with Saccharomyces cerevisiae for simultaneous saccharification and fermentation. Ethanol production was positively tested after five days of incubation with acidified potassium dichromate. PMID:22315612

  8. Patch Testing with Dental Screening Series in Oral Disease

    PubMed Central

    Kim, Tae-Wook; Kim, Woo-Il; Mun, Je-Ho; Song, Margaret; Kim, Hoon-Soo; Kim, Byung-Soo; Kim, Moon-Bum

    2015-01-01

    Background The oral mucosa is constantly exposed to several irritants and allergens including dental materials, but the role of contact allergy in oral disease is obscure. Objective To analyze positive patch test results in patients with oral diseases and evaluate the clinical relevance of oral diseases with contact allergy to dental materials. Methods We retrospectively analyzed patch test results with dental screening series in 44 patients with oral disease from 2004~2011. Results Oral diseases included oral lichen planus (54.5%), cheilitis (27.3%), burning mouth syndrome (9.1%), and others (9.1%). Thirty-one of 44 patients (70.5%) had positive reactions to one or more allergens. The most commonly detected allergens were gold sodium thiosulfate (25.0%) and nickel sulfate (25.0%), followed by potassium dichromate (22.7%), cobalt (15.9%), palladium (6.8%), mercury (4.5%), copper (4.5%), and methylhydroquinone (4.5%). Six of 24 patients with oral lichen planus had a symptom in areas adjacent to dental materials and positive patch test reactions to allergens contained in the suspected dental materials. Conclusion Patch tests with dental screening series are worth considering for oral diseases, especially for oral lichen planus. PMID:26273153

  9. The mitigative effect of Raphanus sativus oil on chromium-induced geno- and hepatotoxicity in male rats.

    PubMed

    Elshazly, M O; Morgan, Ashraf M; Ali, Merhan E; Abdel-Mawla, Essam; Abd El-Rahman, Sahar S

    2016-05-01

    To study the impact of radish oil on the possible genotoxic and hepatotoxic effects of hexavalent chromium, male rats were divided into 4 groups. Group 1 served as control, group 2 received radish oil at the recommended human therapeutic dose (0.07 mL/kg) by gavage, group 3 received sodium dichromate dihydrate (SDD) 520 mg/L in drinking water, and group 4 received both SDD and radish oil as previously mentioned in groups 2 and 3. All treatments were continued for six months. The results revealed that chromium exposure promoted oxidative stress with a consequently marked hepatic histopathological alterations, increased serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, alfa fetoprotein (AFP) levels, and micronucleated erythrocytes (MNE) % in peripheral blood. Moreover, COMET assay of hepatic DNA revealed that SDD exposure significantly decreased the intact cells %, head diameter, and head DNA % compared to control, indicating DNA damage. However, radish oil co-administration with SDD resulted in marked amendment in the altered parameters as detected by improved liver function markers (ALT and ALP) and AFP level, decreased lipid peroxidation, increased antioxidant markers, inhibited hepatic DNA damage and restored the hepatic histology by preventing the appearance of the altered hepatocytes' foci and decreasing chromium induced histopathological lesions. It could be concluded that radish oil was able to provide a convergent complete protection against the geno- and hepatotoxicity of chromium by its potent antioxidant effect. PMID:27222746

  10. Alternative non-chromatographic method for alcohols determination in Clostridium acetobutylicum fermentations.

    PubMed

    Noriega-Medrano, Laura J; Vega-Estrada, Jesús; Ortega-López, Jaime; Ruiz-Medrano, Roberto; Cristiani-Urbina, Eliseo; Montes-Horcasitas, Maria Del Carmen

    2016-07-01

    An economic, simple, quantitative, and non-chromatographic method for the determination of alcohols using microdiffusion principle has been adapted and validated for acetone-butanol-ethanol (ABE) fermentation samples. This method, based on alcohols oxidation using potassium dichromate in acid medium, and detection by spectrophotometry, was evaluated varying, both, temperature (35°C, 45°C, and 55°C) and reaction time (0 to 125min). With a sample analysis time of 90min at 45°C, a limit of detection (LOD), and a limit of quantification (LOQ) of 0.10, and 0.40g/L, respectively. The proposed method has been successfully applied to determine butanol and ethanol concentrations in ABE fermentation samples with the advantage that multiple samples can be analyzed simultaneously. The measurements obtained with the proposed method were in good agreement with those obtained with the Gas Chromatography Method (GCM). This proposed method is useful for routine analysis of alcohols and screening samples in laboratories and industries. PMID:27155258

  11. Removal of Cr(VI) from Aqueous Solutions Using Powder of Potato Peelings as a Low Cost Sorbent

    PubMed Central

    Mutongo, Farai; Kuipa, Olga; Kuipa, Pardon K.

    2014-01-01

    Potato peels which are a low cost, renewable agroindustry by-product were used for the removal of hexavalent chromium from aqueous effluents. Batch experiments were carried out with an artificial effluent comprising of potassium dichromate in deionised water. The effects of the initial hexavalent chromium concentration, dose of biosorbent, and removal kinetics were explored. An adsorbent dosage of 4 g/L was effective in complete removal of the metal ion, at pH 2.5, in 48 minutes. The kinetic process of Cr(VI) adsorption onto potato peel powder was tested by applying pseudo-first-order and pseudo-second-order models as well as the Elovich kinetic equation to correlate the experimental data and to determine the kinetic parameters. The adsorption data were correlated by the Langmuir and Freundlich isotherms. A maximum monolayer adsorption capacity of 3.28 mg/g was calculated using the Langmuir adsorption isotherm, suggesting a functional group limited adsorption process. The results confirmed that potato peels are an effective biosorbent for the removal of hexavalent chromium from effluent. PMID:25136289

  12. 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. PMID:22326242

  13. Effect of Chromium(VI) Toxicity on Enzymes of Nitrogen Metabolism in Clusterbean (Cyamopsis tetragonoloba L.)

    PubMed Central

    Sangwan, Punesh; Joshi, U. N.

    2014-01-01

    Heavy metals are the intrinsic component of the environment with both essential and nonessential types. Their excessive levels pose a threat to plant growth and yield. Also, some heavy metals are toxic to plants even at very low concentrations. The present investigation (a pot experiment) was conducted to determine the affects of varying chromium(VI) levels (0.0, 0.5, 1.0, 2.0, and 4.0 mg chromium(VI) kg−1 soil in the form of potassium dichromate) on the key enzymes of nitrogen metabolism in clusterbean. Chromium treatment adversely affect nitrogenase, nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase in various plant organs at different growth stages as specific enzyme activity of these enzymes decreased with an increase in chromium(VI) levels from 0 to 2.0 mg chromium(VI) kg−1 soil and 4.0 mg chromium(VI) kg−1 soil was found to be lethal to clusterbean plants. In general, the enzyme activity increased with advancement of growth to reach maximum at flowering stage and thereafter decreased at grain filling stage. PMID:24744916

  14. Hexavalent chromium damages chamomile plants by alteration of antioxidants and its uptake is prevented by calcium.

    PubMed

    Kováčik, Jozef; Babula, Petr; Hedbavny, Josef; Klejdus, Bořivoj

    2014-05-30

    Toxicity of low (3μM) and high (60 and 120μM) concentrations of hexavalent chromium/Cr(VI) in chamomile plants was studied. Fluorescence staining confirmed reduction of Cr(VI) to Cr(III). Cr was mainly accumulated in the roots with translocation factor <0.007. Notwithstanding this, both shoots and roots revealed increase in oxidative stress and depletion of glutathione, total thiols, ascorbic acid and activities of glutathione reductase and partially ascorbate peroxidase mainly at 120μM Cr. Though some protective mechanisms were detected (elevation of nitric oxide, enhancement of GPX activity and increase in phenols and lignin), this was not sufficient to counteract the oxidative damage. Consequently, soluble proteins, tissue water content and biomass production were considerably depleted. Surprising increase in some mineral nutrients in roots (Ca, Fe, Zn and Cu) was also detected. Subsequent experiment confirmed that exogenous calcium suppressed oxidative symptoms and Cr uptake but growth of chamomile seedlings was not improved. Alteration of naturally present reductants could be a reason for Cr(III) signal detected using specific fluorescence reagent: in vitro assay confirmed disappearance of ascorbic acid in equimolar mixture with dichromate (>96% at pH 4 and 7) while such response of glutathione was substantially less visible. PMID:24727012

  15. Reproductive toxicity of chromium in adult bonnet monkeys (Macaca radiata Geoffrey). Reversible oxidative stress in the semen

    SciTech Connect

    Subramanian, Senthivinayagam . E-mail: subbi100@yahoo.co.uk; Rajendiran, Gopalakrishnan; Sekhar, Pasupathi; Gowri, Chandrahasan; Govindarajulu, Pera; Aruldhas, Mariajoseph Michael

    2006-09-15

    The present study was designed to test the hypothesis that oxidative stress mediates chromium-induced reproductive toxicity. Monthly semen samples were collected from adult monkeys (Macaca radiata), which were exposed to varying doses (50, 100, 200 and 400 ppm) of chromium (as potassium dichromate) for 6 months through drinking water. Chromium treatment decreased sperm count, sperm forward motility and the specific activities of antioxidant enzymes, superoxide dismutase and catalase, and the concentration of reduced glutathione in both seminal plasma and sperm in a dose- and duration-dependent manner. On the other hand, the quantum of hydrogen peroxide in the seminal plasma/sperm from monkeys exposed to chromium increased with increasing dose and duration of chromium exposure. All these changes were reversed after 6 months of chromium-free exposure period. Simultaneous supplementation of vitamin C (0.5 g/L; 1.0 g/L; 2.0 g/L) prevented the development of chromium-induced oxidative stress. Data support the hypothesis and show that chronic chromium exposure induces a reversible oxidative stress in the seminal plasma and sperm by creating an imbalance between reactive oxygen species and antioxidant system, leading to sperm death and reduced motility of live sperm.

  16. Efficient and aberration-free wavefront reconstruction from holograms illuminated at wavelengths differing from the forming wavelength.

    PubMed

    Lin, L H; Doherty, E T

    1971-06-01

    Recording materials producing higher efficiency, low absorption holograms are usually photosensitive only to blue and uv light. If a hologram is formed at a blue wavelength in such a material and is illuminated at a red wavelength, generally the reconstructed wavefront is aberrated, and the resolution of the image is reduced. A method of hologram formation is described that can alleviate this problem. In this method, a hologram H(1) is formed first at the red wavelength lambda(1) in a photographic emulsion. This hologram is then illuminated at the blue wavelength lambda(2) The diffracted wave from H(1) is used as the subject wave for forming the desired high efficiency hologram H(2). If certain requirements are met, illumination of H(2) at lambda(1) can produce an aberration-free reconstruction of the original subject wave. Experimental results of forming H(2) of a point source on dichromated gelatin film are presented. The hologram was formed at lambda(2) = 4800 A but could reconstruct an aberration-free wavefront at lambda(1) = 6328 A. The hologram had about 80% diffraction efficiency and essentially no absorption loss. PMID:20111111

  17. Planar holographic spectrum-splitting PV module design

    NASA Astrophysics Data System (ADS)

    Gordon, Michael; Zhang, Deming; Vorndran, Shelby; Russo, Juan M.; Luscombe, Christine K.; Shaheen, Sean E.; Kostuk, Raymond K.

    2012-10-01

    A design is presented for a planar spectrum-splitting photovoltaic (PV) module using Holographic Optical Elements (HOEs). A repeating array of HOEs diffracts portions of the solar spectrum onto different PV materials arranged in alternating strips. Several combinations of candidate PV materials are explored, and theoretical power conversion efficiency is quantified and compared for each case. The holograms are recorded in dichromated gelatin (DCG) film, an inexpensive material which is easily encapsulated directly into the panel. If desired, the holograms can focus the light to achieve concentration. The side-by-side split spectrum layout has advantages compared to a stacked tandem cell approach: since the cells are electrically isolated, current matching constraints are eliminated. Combinations of dissimilar types of cells are also possible: including crystalline, thin film, and organic PV cells. Configurations which yield significant efficiency gain using relatively inexpensive PV materials are of particular interest. A method used to optimize HOE design to work with a different candidate cells and different package aspect ratios is developed and presented. (Aspect ratio is width of the cell strips vs. the thickness of the panel) The relationship between aspect ratio and HOE performance properties is demonstrated. These properties include diffraction efficiency, spectral selectivity, tracking alignment sensitivity, and uniformity of cell illumination.

  18. Investigation on the high efficiency volume Bragg gratings performances for spectrometry in space environment: preliminary results

    NASA Astrophysics Data System (ADS)

    Loicq, Jérôme; Gaspar Venancio, Luis Miguel; Georges, Marc

    2012-09-01

    The special properties of Volume Bragg Gratings (VBGs) make them good candidates for spectrometry applications where high spectral resolution, low level of straylight and low polarisation sensitivity are required. Therefore it is of interest to assess the maturity and suitability of VBGs as enabling technology for future ESA missions with demanding requirements for spectrometry. The VBGs suitability for space application is being investigated in the frame of a project led by CSL and funded by the European Space Agency. The goal of this work is twofold: first the theoretical advantages and drawbacks of VBGs with respect to other technologies with identical functionalities are assessed, and second the performances of VBG samples in a representative space environment are experimentally evaluated. The performances of samples of two VBGs technologies, the Photo-Thermo-Refractive (PTR) glass and the DiChromated Gelatine (DCG), are assessed and compared in the Hα, O2-B and NIR bands. The tests are performed under vacuum condition combined with temperature cycling in the range of 200 K to 300K. A dedicated test bench experiment is designed to evaluate the impact of temperature on the spectral efficiency and to determine the optical wavefront error of the diffracted beam. Furthermore the diffraction efficiency degradation under gamma irradiation is assessed. Finally the straylight, the diffraction efficiency under conical incidence and the polarisation sensitivity is evaluated.

  19. Chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade uranyl nitrate solutions

    SciTech Connect

    Not Available

    1981-01-01

    The standard covers analytical procedures to determine compliance of nuclear-grade uranyl nitrate solution to specifications. The following methods are described in detail: uranium by ferrous sulfate reduction-potassium dichromate titrimetry and by ignition gravimetry; specific gravity by pycnometry; free acid by oxalate complexation; thorium by the Arsenazo(III) (photometric) method; chromium by the diphenylcarbazide (photometric) method; molybdenum by the thiocyanate (photometric) method; halogens separation by steam distillation; fluorine by specific ion electrode; halogen distillate analysis: chloride, bromide and iodide by amperometric microtitrimetry; bromine by the fluorescein (photometric) method; sulfate sulfur by (photometric) turbidimetry; phosphorus by the molybdenum blue (photometric) method; silicon by the molybdenum blue (photometric) method; carbon by persulfate oxidation-acid titrimetry; nonvolatile impurities by spectrography; volatile impurities by rotating-disk spark spectrography; boron by emission spectrography; impurity elements by spark source mass spectrography; isotopic composition by multiple filament surface-ionization mass spectrometry; uranium-232 by alpha spectrometry; total alpha activity by direct alpha counting; fission product activity by beta and gamma counting; entrained organic matter by infrared spectrophotometry. (JMT)

  20. A simplified method for generating periodic nanostructures by interference lithography without the use of an anti-reflection coating

    NASA Astrophysics Data System (ADS)

    Kapon, Omree; Muallem, Merav; Palatnik, Alex; Aviv, Hagit; Tischler, Yaakov. R.

    2015-11-01

    Interference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or more simply a one beam configuration based on a Lloyd's Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser, and can be etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.

  1. Efficient adsorption of both methyl orange and chromium from their aqueous mixtures using a quaternary ammonium salt modified chitosan magnetic composite adsorbent.

    PubMed

    Li, Kun; Li, Pei; Cai, Jun; Xiao, Shoujun; Yang, Hu; Li, Aimin

    2016-07-01

    A quaternary ammonium salt modified chitosan magnetic composite adsorbent (CS-CTA-MCM) was prepared by combination of Fe3O4 nanoparticles. Various techniques were used to characterize the molecular structure, surface morphology, and magnetic feature of this composite adsorbent. CS-CTA-MCM was employed for the removal of Cr(VI) and methyl orange (MO), an anionic dye, from water in respective single and binary systems. Compared with chitosan magnetic adsorbent (CS-MCM) without modification, CS-CTA-MCM shows evidently improved adsorption capacities for both pollutants ascribed to the additional quaternary ammonium salt groups. Based on the adsorption equilibrium study, MO bears more affinity to CS-CTA-MCM than Cr(VI) causing a considerable extent of preferential adsorption of dye over metal ions in their aqueous mixture. However, at weak acidic solutions, Cr(VI) adsorption is evidently improved due to more efficient Cr(VI) forms, i.e. dichromate and monovalent chromate, binding to this chitosan-based adsorbent. Thus chromium could be efficient removal together with MO at suitable pH conditions. The adsorption isotherms and kinetics indicate that adsorptions of Cr(VI) and MO by CS-CTA-MCM both follow a homogeneous monolayer chemisorption process. This magnetic adsorbent after saturated adsorption could be rapidly separated from water and easily regenerated using dilute NaOH aqueous solutions then virtually reused with little adsorption capacity loss. PMID:27060639

  2. Factors driving carbon mineralization priming effect in a soil amended with different types of biochar

    NASA Astrophysics Data System (ADS)

    Cely, P.; Tarquis, A. M.; Paz-Ferreiro, J.; Méndez, A.; Gascó, G.

    2014-03-01

    The effect of biochar on soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on soil CO2 emissions and in different physicochemical properties. For this purpose, a sandy-loam soil was amended with the three biochars (BI, BII and BIII) at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving's from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2) greater than 0.97. Results shown a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related with different biochar properties such as ash content, volatile matter, fixed carbon, organic carbon oxidised with dichromate, soluble carbon and metal and phenolic substances content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

  3. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    NASA Astrophysics Data System (ADS)

    Gómez Colín, R.; García Juárez, A.; Zaldívar Huerta, I. E.; Marquina, A. Vera; García Delgado, L. A.; Leal Cruz, A. L.; Gómez Fuentes, R.

    2016-03-01

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade.

  4. A simplified method for generating periodic nanostructures by interference lithography without the use of an anti-reflection coating

    SciTech Connect

    Kapon, Omree; Muallem, Merav; Palatnik, Alex; Aviv, Hagit; Tischler, Yaakov R.

    2015-11-16

    Interference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or more simply a one beam configuration based on a Lloyd's Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser, and can be etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.

  5. Acute toxicity impacts of Euphorbia hirta L extract on behavior, organs body weight index and histopathology of organs of the mice and Artemia salina

    PubMed Central

    Rajeh, Mohammad Abu Basma; Kwan, Yuet Ping; Zakaria, Zuraini; Latha, Lachimanan Yoga; Jothy, Subramanion L.; Sasidharan, Sreenivasan

    2012-01-01

    Background: The methanol extract of Euphorbia hirta L (Euphorbiaceae), which is used in traditional medicines, was tested for in vivo toxicity. Materials and Methods: In vivo brine shrimp lethality assay and oral acute toxicity study at single high dose of 5000 mg/kg and observation for 14 days in mice were used to study the toxic effect of E. hirta. Results: Brine shrimp lethality assay was used to calculate the median lethal concentration (LC50) of E. hirta (for leaves, stems, flowers and roots) methanolic extracts at concentrations from 100 to 0.07 mg/ml. The LC50 values of 1.589, 1.420, 0.206 and 0.0827 mg/ml were obtained for stems, leaves, flowers and roots, respectively. Potassium dichromate (the positive control) had LC50 value of 0.00758 mg/ml. The acute oral toxicity study of the leaf extract resulted in one third mortality and mild behavioral changes among the treated mice. No significant statistical differences found between body weight, relative (%) and absolute (g) organ weights of treated and untreated groups (P> 0.05). Gross and microscopic examination of the vital organ tissues revealed no differences between control and treated mice. All the tissues appeared normal. Conclusions: E. hirta leaves methanol extract has exhibited mild toxic effects in mice. PMID:22923956

  6. Sexual maturation and fertility of male and female mice exposed prenatally and postnatally to trivalent and hexavalent chromium compounds.

    PubMed

    Al-Hamood, M H; Elbetieha, A; Bataineh, H

    1998-01-01

    The reproductive toxicity of trivalent and hexavalent chromium compounds was investigated in male and female mice exposed to 1000 ppm chromium chloride and potassium dichromate via their mother during gestational and lactational periods. Fertility was reduced in male offspring exposed to either trivalent or hexavalent chromium compounds. Body weights and weights of testes, seminal vesicles and preputial glands were reduced in trivalent-exposed male offspring. The exposure of female mice offspring to trivalent and hexavalent chromium compounds delayed sexual maturation. Fertility was reduced in female offspring exposed to either trivalent or hexavalent chromium compounds. The exposure of female mice to hexavalent chromium compound reduced the number of implantations and viable fetuses respectively. Body weight and weights of ovaries and uteri were reduced in trivalent-exposed female offspring. The results indicate that under our experimental conditions, the exposure of male and female mice offspring to either trivalent or hexavalent chromium compounds during gestational and lactational periods impair reproductive functions and fertility in adulthood. PMID:9801270

  7. Potential of Live Spirulina platensis on Biosorption of Hexavalent Chromium and Its Conversion to Trivalent Chromium.

    PubMed

    Colla, Luciane Maria; Dal'Magro, Clinei; De Rossi, Andreia; Thomé, Antônio; Reinehr, Christian Oliveira; Bertolin, Telma Elita; Costa, Jorge Alberto Vieira

    2015-01-01

    Microalga biomass has been described worldwide according their capacity to realize biosorption of toxic metals. Chromium is one of the most toxic metals that could contaminate superficial and underground water. Considering the importance of Spirulina biomass in production of supplements for humans and for animal feed we assessed the biosorption of hexavalent chromium by living Spirulina platensis and its capacity to convert hexavalent chromium to trivalent chromium, less toxic, through its metabolism during growth. The active biomass was grown in Zarrouk medium diluted to 50% with distilled water, keeping the experiments under controlled conditions of aeration, temperature of 30°C and lighting of 1,800 lux. Hexavalent chromium was added using a potassium dichromate solution in fed-batch mode with the aim of evaluate the effect of several additions contaminant in the kinetic parameters of the culture. Cell growth was affected by the presence of chromium added at the beginning of cultures, and the best growth rates were obtained at lower metal concentrations in the medium. The biomass removed until 65.2% of hexavalent chromium added to the media, being 90.4% converted into trivalent chromium in the media and 9.6% retained in the biomass as trivalent chromium (0.931 mg.g(-1)). PMID:25436450

  8. Determination of mercury in whole blood and urine by inductively coupled plasma mass spectrometry.

    PubMed

    Fong, Bonnie Mei Wah; Siu, Tak Shing; Lee, Joseph Sai Kit; Tam, Sidney

    2007-06-01

    The conventional method for the determination of mercury in clinical samples is cold vapor atomic absorption spectrometry. Sample digestion or pretreatment require large sample volume and long sample preparation time. The inductively coupled plasma mass spectrometry (ICP-MS) method developed in this study requires only 100 microL of sample with practically no preparation, except for dilution with diluent. Significant savings in sample volumes, reagents, technician time, and analysis time are realized. Among different types of diluents, the one containing acid, tert-butanol, and potassium dichromate gave the best results to remove the mercury memory effect. The interassay precisions for whole blood and urine were < 5% and < 8%, respectively, and the intra-assay precisions were < 3% and < 7%, respectively. The lower limits of detection were 0.13, 0.17, and 0.26 microg/L for aqueous standard, urine, and whole blood, respectively. The developed ICP-MS method correlated well with the atomic absorption method and can offer an alternative to the atomic absorption method for mercury analysis with less sample volume requirement as well as shorter analysis time. PMID:17579973

  9. Efficient production of methane from artificial garbage waste by a cylindrical bioelectrochemical reactor containing carbon fiber textiles.

    PubMed

    Sasaki, Daisuke; Sasaki, Kengo; Watanabe, Atsushi; Morita, Masahiko; Igarashi, Yasuo; Ohmura, Naoya

    2013-01-01

    A cylindrical bioelectrochemical reactor (BER) containing carbon fiber textiles (CFT; BER + CFT) has characteristics of bioelectrochemical and packed-bed systems. In this study, utility of a cylindrical BER + CFT for degradation of a garbage slurry and recovery of biogas was investigated by applying 10% dog food slurry. The working electrode potential was electrochemically regulated at -0.8 V (vs. Ag/AgCl). Stable methane production of 9.37 L-CH4 · L-1 · day-1 and dichromate chemical oxygen demand (CODcr) removal of 62.5% were observed, even at a high organic loading rate (OLR) of 89.3 g-CODcr · L-1 · day-1. Given energy as methane (372.6 kJ · L-1 · day-1) was much higher than input electric energy to the working electrode (0.6 kJ · L-1 · day-1) at this OLR. Methanogens were highly retained in CFT by direct attachment to the cathodic working electrodes (52.3%; ratio of methanogens to prokaryotes), compared with the suspended fraction (31.2%), probably contributing to the acceleration of organic material degradation and removal of organic acids. These results provide insight into the application of cylindrical BER + CFT in efficient methane production from garbage waste including a high percentage of solid fraction. PMID:23497472

  10. Influence of temperature on Cryptosporidium parvum oocyst infectivity in river water samples as detected by tissue culture assay.

    PubMed

    Pokorny, Nicholas J; Weir, Susan C; Carreno, Ramon A; Trevors, Jack T; Lee, Hung

    2002-06-01

    Cryptosporidium parvum oocysts were stored in 1-ml aliquots of filtered river water at -20, 4, 10, and 21-23 C in the dark. Oocysts were also added to filter-sterilized river water samples and stored at 21-23 C. The infectivity of oocysts stored under different conditions was assayed at weekly intervals through infection of human adenocarcinoma ileocecal (HCT-8) cell monolayers. Wells containing between 10 and 100 foci of infection were enumerated by immunofluorescent microscopy, and the number of infective oocysts was calculated. No infectious oocysts were detected after 1 wk at -20 C. The number of infective oocysts stored at 4 C decreased 5-fold, and the number of those stored at 10 C decreased 2.5-fold after 14 wk. The infectivity of oocysts stored in potassium dichromate (positive control) at 4 C decreased 2-fold over 14 wk. The number of infective oocysts in filter-sterilized and non-filter-sterilized river water stored at 21-23 C decreased by 3.3 and 2.6 log units, respectively, over 12 wk, and no foci of infection were detected at 14 wk. The results show that as temperature increased from 4 to 23 C, the duration of oocyst infectivity decreased. PMID:12099446

  11. METHOD FOR SEPARATION OF PLUTONIUM FROM URANIUM AND FISSION PRODUCTS BY SOLVENT EXTRACTION

    DOEpatents

    Seaborg, G.T.; Blaedel, W.J.; Walling, M.T. Jr.

    1960-08-23

    A process is given for separating from each other uranium, plutonium, and fission products in an aqueous nitric acid solution by the so-called Redox process. The plutonium is first oxidized to the hexavalent state, e.g., with a water-soluble dichromate or sodium bismuthate, preferably together with a holding oxidant such as potassium bromate. potassium permanganate, or an excess of the oxidizing agent. The solution is then contacted with a water-immiscible organic solvent, preferably hexone. whereby uranium and plutonium are extracted while the fission products remain in the aqueous solution. The separated organic phase is then contacted with an aqueous solution of a reducing agent, with or without a holding reductant (e.g., with a ferrous salt plus hydrazine or with ferrous sulfamate), whereby plutonium is reduced to the trivalent state and back- extracted into the aqueous solution. The uranium may finally be back-extracted from the organic solvent (e.g., with a 0.1 N nitric acid).

  12. The prevalence of ovine Eimeria infection in Rudsar, North of Iran, (2011-2012).

    PubMed

    Nourollahi-Fard, S R; Khedri, J; Ghashghaei, O; Mohammadyari, N; Sharifi, H

    2016-09-01

    This study was undertaken to determine the prevalence of Eimeria infection in sheep in Rudsar, North of Iran, in period of 1 year (March 2011 to March 2012). The samples (approximately 3-5 grams of faeces) were collected from the rectum of 270 sheep and transferred to the parasitology laboratory. Eimeria species were identified following sporulation of faeces in a thin layer of 2.5 % potassium dichromate for one or 2 weeks at 27 °C. Out of 270 faecal samples examined, 170[(63.0 %; 95 % Confidence Interval (CI) 56.9-68.7)] were positive for Eimeria spp. Five species of Eimeria, including E. ahsata, E. ovina, E. crandallis, E. parva and E. ovinoidalis were identified in faecal samples by modified McMaster technique. The most frequent species was E. crandallis. Sheep were considered in four age groups (less than 1 year old, 1-2 years old, 2-3 years old and over 3 years old).The results also indicated that less than 1 year old sheep have greater infection ratio as compare with older animals. Female had significantly higher prevalence of Eimeria than male. Higher infection was seen in females compare to males and in winter compare to summer. Parasitological gross and microscopic examinations revealed Eimeria infection is common in sheep of Rudsar, North Iran. PMID:27605817

  13. The Remedial Efficacy of Spirulina platensis versus Chromium-Induced Nephrotoxicity in Male Sprague-Dawley Rats

    PubMed Central

    Elshazly, M. O.; Abd El-Rahman, Sahar S.; Morgan, Ashraf M.; Ali, Merhan E.

    2015-01-01

    This study was conducted to investigate the possible protective effect of Spirulina platensis against chromium-induced nephrotoxicity. A total of 36 adult male Sprague-Dawley rats were divided into 4 equal groups (Gps). Gp1 served as control, rats of Gps 2, 3, and 4 were exposed to Spirulina platensis (300 mg/kg b.wt per os) and sodium dichromate dihydrate (SDD) via drinking water at concentration of 520 mg /l respectively. Chromium administration caused alterations in the renal function markers as evidenced by significant increase of blood urea and creatinine levels accompanied with significant increase in kidney’s chromium residues and MDA level as well as decreased catalase activity and glutathion content in kidney tissue. Histologically, Cr provoked deleterious changes including: vascular congestion, wide spread tubular epithelium necrobiotic changes, atrophy of glomerular tuft and proliferative hyperplasia. The latter was accompanied with positive PCNA expression in kidney tissues as well as DNA ploidy interpretation of major cellular population of degenerated cells, appearance of tetraploid cells, high proliferation index and high DNA index. Morphometrical measurements revealed marked glomerular and tubular lumen alterations. On contrary, spirulina co-treatment with Cr significantly restored the histopathological changes, antioxidants and renal function markers and all the previously mentioned changes as well. PMID:26029926

  14. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF

    SciTech Connect

    Ondrejcin, R.S.; McLaughlin, B.D.

    1980-04-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.

  15. Synthesis, characterization and antitumor activity of cis-bis(acylthioureato) platinum(II) complexes, cis-[PtL(2)] [HL=N,N-diphenyl-N'-benzoylthiourea or HL=N,N-diphenyl-N'-(p-nitrobenzoyl)thiourea].

    PubMed

    Hernández, Wilfredo; Spodine, Evgenia; Muñoz, Juan Carlos; Beyer, Lothar; Schröder, Uwe; Ferreira, Jorge; Pavani, Mario

    2003-01-01

    A low-molecular weight chromium-containing fraction of the material resulting from dichromate reduction by bovine liver homogenate was investigated by NMR and ES-MS. The ES-MS spectrum showed a readily detectable peak at m/z 786.1. The same molecular weight reasonably agreed with the relatively low diffusion coefficient measured by NMR-DOSY experiments on the main species observed in the (1)H NMR spectrum. At least two downfield shifted and broad paramagnetic signals were apparent in the (1)H NMR spectrum. Temperature dependence of chemical shift was exploited in order to estimate the diamagnetic shift of the signals in the diamagnetic region of the spectrum. 2D TOCSY, NOESY, COSY and (1)H-(13)C HMQC spectra revealed the presence of aromatic protons (which were assigned as His residues), Gly and some other short chain amino-acids. Combinations of the molecular masses of such components together with acetate (which is present in the solution) and chromium atoms allowed a tentative proposal of a model for the compound. PMID:18365059

  16. Determination of betamethasone and triamcinolone acetonide by GC-NCI-MS in excreta of treated animals and development of a fast oxidation procedure for derivatisation of corticosteroids.

    PubMed

    Courtheyn, D; Vercammen, J; Logghe, M; Seghers, H; De Wasch, K; De Brabander, H

    1998-12-01

    The use of corticosteroids in combination with other hormonal substances has long been known to result in increased mass gain with bovines. Practice has demonstrated, however, that even the single use of a glucocorticoid may result in growth promoting effects. In addition to the popular dexamethasone, more recently other corticosteroids have also been misused for fattening purposes. The first part of this study deals with the detection of two of them, namely betamethasone and triamcinolone acetonide. Betamethasone was administered orally to a cow at a dose of 50 mg d-1 for 5 d, then later the same cow was injected intramuscularly with a dose of 50 mg of betamethasone dipropionate. Excretion in urine and faeces was followed with both HPLC-enzyme immunoassay and a previously described method based on negative chemical ionization mass spectrometry (NCI-MS) after oxidation. For the triamcinolone acetonide study a cow was treated with 50 mg d-1 of the drug during a 7 d period. Excretion in faeces was followed with GC-NCI-MS. As triamcinolone acetonide is resistant to the previously described oxidation procedure, however, a hydrolysis step had to be introduced prior to oxidation. In addition to this specific modification necessary for triamcinolone acetonide, in a subsequent part of this study the original oxidation procedure with pyridinium chlorochromate was re-investigated especially to shorten the procedure. With the introduction of potassium dichromate the reaction time could be decreased from 3 h to 10 min. PMID:10435270

  17. Effect of pyrolysis temperature on the chemical oxidation stability of bamboo biochar.

    PubMed

    Chen, Dengyu; Yu, Xinzhi; Song, Chao; Pang, Xiaoli; Huang, Jing; Li, Yanjun

    2016-10-01

    Biochar produced by biomass pyrolysis has the advantage of carbon sequestration. However, some of the carbon atoms in biochar are not very stable. In this study, the effect of pyrolysis temperature on the chemical oxidation stability of bamboo biochar was investigated using the atomic ratios of H/C and O/C, Fourier transform infrared spectroscopy, and potassium dichromate (K2Cr2O7) oxidation spectrophotometric method. The results show that the carbon yield and ratios of H/C and O/C decreased from 71.72%, 0.71, and 0.32 to 38.48%, 0.22, and 0.06, respectively, as the temperature was increased from 300°C to 700°C. Moreover, the main oxygen-containing functional groups gradually decreased, while the degree of aromatization increased accordingly. The biochar showed a better stability at a higher pyrolysis temperature. The proportion of carbon loss, i.e., the amount of oxidized carbon with respect to the total carbon of the biochar, decreased from 16.52% to 6.69% with increasing temperature. PMID:27481469

  18. Photopatch and UV-irradiated patch testing in photosensitive dermatitis

    PubMed Central

    Rai, Reena; Thomas, Maria

    2016-01-01

    Background: The photopatch test is used to detect photoallergic reactions to various antigens such as sunscreens and drugs. Photosensitive dermatitis can be caused due to antigens like parthenium, fragrances, rubbers and metals. The photopatch test does not contain these antigens. Therefore, the Indian Standard Series (ISS) along with the Standard photopatch series from Chemotechnique Diagnostics, Sweden was used to detect light induced antigens. Aim: To detect light induced antigens in patients with photosensitive dermatitis. Methods: This study was done in a descriptive, observer blinded manner. Photopatch test and ISS were applied in duplicate on the patient's back by the standard method. After 24 hours, readings were recorded according to ICDRG criteria. One side was closed and other side irradiated with 14 J/cm2 of UVA and a second set of readings were recorded after 48 hrs. Result: The highest positivity was obtained with parthenium, with 18 out of 35 (51%) patients showing a positive patch test reaction with both photoallergic contact dermatitis and photoaggravation. Four patients (11%) showed positive patch test reaction suggestive of contact dermatitis to potassium dichromate and fragrance mix. Six patients had contact dermatitis to numerous antigens such as nickel, cobalt, chinoform and para-phenylenediamine. None of these patients showed photoaggravation on patch testing. Conclusion: Parthenium was found to cause photoallergy, contact dermatitis with photoaggravation and contact allergy. Hence, photopatch test and UV irradiated patch test can be an important tool to detect light induced antigens in patients with photosensitive dermatitis. PMID:26955581

  19. Contact Hypersensitivity to European Baseline Series and Corticosteroid Series Haptens in a Population of Adult Patients with Contact Eczema.

    PubMed

    Kot, Marek; Bogaczewicz, Jarosław; Kręcisz, Beata; Woźniacka, Anna

    2016-04-01

    Contact eczema (CE) is one of the most common skin diseases and is regarded as a reaction pattern. However, the skin can react in the same way to different stimuli, some of which may act together. The golden standard in the diagnosis of allergic contact dermatitis (ACD) is the patch test. Contact allergy to topical corticosteroids is known to be gradually rising, and this represents a significant problem in the treatment of contact eczema. The aim of this study was to evaluate the prevalence of contact allergy to European Baseline Series and Corticosteroid Series haptens in a population of patients with CE. A group of 126 patients with the clinical diagnosis of contact eczema were patch tested with 28 European Baseline Series allergens and 8 corticosteroid allergens in different concentrations and in different media: 80 (64.5%) women and 46 (36.5%) men, mean age 50.4 years. The average duration of CE was 6.9 years. In total, 65 patients (51.6%) demonstrated an allergic reaction to at least one European Baseline Series allergen, and 22 patients (17.4%) to at least one corticosteroid. The most common allergens giving positive results were nickel sulfate (26.2%), cobalt chloride (15.1%), budesonide (14.3%), potassium dichromate (13.5%), and myroxylon pereirae resin (MPR) (11.9%). According our data, the European Baseline Series tests allow the cause of ACD to be identified in over 50% of cases. PMID:27149128

  20. The corrosion protection of aluminum by various anodizing treatments

    NASA Technical Reports Server (NTRS)

    Danford, Merlin D.

    1989-01-01

    Corrosion protection to 6061-T6 aluminum, afforded by both teflon-impregnated anodized coats (Polylube and Tufram) and hard-anodized coats (water sealed and dichromate sealed), was studied at both pH 5.5 and pH 9.5, with an exposure period of 28 days in 3.5 percent NaCl solution (25 C) for each specimen. In general, corrosion protection for all specimens was better at pH 9.5 than at pH 5.5. Protection by a Tufram coat proved superior to that afforded by Polylube at each pH, with corrosion protection by the hard-anodized, water-sealed coat at pH 9.5 providing the best protection. Electrochemical work in each case was corroborated by microscopic examination of the coats after exposure. Corrosion protection by Tufram at pH 9.5 was most comparable to that of the hard-anodized samples, although pitting and some cracking of the coat did occur.

  1. Eects of Post Deposition Treatments on Vacuum Evaporated CdTe Thin Films and CdS=CdTe Heterojunction Devices

    NASA Astrophysics Data System (ADS)

    Bayhan, Habibe; Erçelebý, Çiðdem

    1998-05-01

    CdTe, CdS thin films and n-CdS/p-CdTe heterostructures have been prepared by conventional vacuum evaporation technique. Some post deposition treatments to optimize the device efficiency have been analyzed and the effects of the individual process steps on the material and device properties were investigated. Annealing in air with and without CdCl2-treatment decreased the CdTe resistivity. The CdCl2-dip followed by annealing in air at 300°C for 5 min improved the grain size and polycrystalline nature of CdTe thin films. Solar efficiency improvements were achieved when heterojunctions were prepared on successively treated (i.e. etched, air annealed, CdCl2-processed) CdTe surfaces. Etching of the CdTe surface with potassium dichromate solution prior to metal contact deposition lead to the formation of low-resistance Au contacts and increase in open circuit voltage and fill factor values.

  2. Kinetics of the reduction of chromium(VI) by vitamin C.

    PubMed

    Xu, Xiang-Rong; Li, Hua-Bin; Gu, Ji-Dong; Li, Xiao-Yan

    2005-06-01

    The kinetics of the reduction of Cr(VI) to Cr(III) by vitamin C was studied using potassium dichromate solution as the model pollutant. Effects of the concentration of vitamin C, pH, temperature, and irradiation on the reduction of Cr(VI) were examined. The kinetics of Cr(VI) reduction by vitamin C can be described as -d[Cr(VI)]/dt = 0.0156 (microM s(-1).[Cr(VI)][vitamin C] (pH 5), where dt is the differential function (d) of time (t). The activation entropy (deltaS) and enthalpy (deltaH) are 42.4 kJ mol(-1) and -71.0 J mol(-1) K(-1), respectively, and the activation energy at 298 K is 63.5 kJ mol(-1). The advantages of vitamin C as a reductant are as follows: It is an important biological reductant in humans and animals, and it is not toxic. Toxic Cr(VI) can be reduced by vitamin C not only in acidic conditions but also in alkaline solutions (pH 9); furthermore, the reduction was shown to occur both under the irradiation and in the dark. The present results suggest that vitamin C could be used effectively in the remediation of Cr(VI)-contaminated soil and groundwater in a wide range of pH, with or without sunlight. PMID:16117105

  3. Reduction of hexavalent chromium by ascorbic acid in aqueous solutions.

    PubMed

    Xu, Xiang-Rong; Li, Hua-Bin; Li, Xiao-Yan; Gu, Ji-Dong

    2004-11-01

    Hexavalent chromium is a priority pollutant in the USA and many other countries. Reduction of Cr(VI) to Cr(III) is environmentally favorable as the latter species is not toxic to most living organisms and also has a low mobility and bioavailability. Reduction of Cr(VI) by ascorbic acid (vitamin C) as a reductant was studied using potassium dichromate solution as the model pollutant. Effects of concentration of vitamin C, pH, temperature, irradiation and reaction time on the reduction of Cr(VI) were examined. Cr(VI) might be reduced by vitamin C not only in acidic conditions but also in weakly alkaline solutions. The reduction of Cr(VI) by vitamin C might occur not only under irradiation but also in the dark. Vitamin C is an important biological reductant in humans and animals, and not toxic. It is water-soluble and can easily permeate through various types of soils. The results indicate that vitamin C could be used in effective remediation of Cr(VI)-contaminated soils and groundwater in a wide range of pH, with or without sunlight. PMID:15488923

  4. 18-Substituted steroids: synthesis of 18-hydroxycortisol (11 beta,17 alpha,18,21-tetrahydroxy-4-pregnene-3,20-dione) and 18-hydroxycortisone (17 alpha,18,21-trihydroxy-4-pregnene-3,11,20-trione).

    PubMed

    Gomez-Sanchez, C E; Kirk, D N; Farrant, R D; Milewich, L

    1985-01-01

    The isolation of 18-hydroxycortisol from the urine of patients with primary aldosteronism was recently described and no synthetic procedure was available for its preparation. The C-13 angular methyl group of prednisolone-17 alpha,21-acetonide-11 beta-nitrite was functionalized by photolysis in the presence of oxygen to give the product 18-hydroxy-prednisolone-17 alpha,21-acetonide-18-nitrate. The 18-nitrate was reduced with zinc and ammonium acetate to the corresponding 18-hydroxy compound, 18-hydroxy-prednisolone-17 alpha,21-acetonide. Homogeneous hydrogenation with Tris(triphenyl-phosphine)rhodium (I) chloride as catalyst resulted in the formation of 18-hydroxy-cortisol-17 alpha,21-acetonide. Acid hydrolysis of the latter compound gave 18-hydroxycortisol. Oxidation of 18-hydroxycortisol-17 alpha,21-acetonide with pyridinium dichromate followed by acid hydrolysis gave 18-hydroxycortisone. The 18-hydroxylated steroids exist as the 18,21-hemiacetals. Catalytic reduction with tritium gas with Tris(triphenyl-phosphine)rhodium (I) chloride of 18-hydroxyprednisolone-17 alpha,21-acetonide and acid hydrolysis gave [1,2(3)H]18-hydroxycortisol. PMID:3974224

  5. Developmental toxicity, acute toxicity and mutagenicity testing in freshwater snails Biomphalaria glabrata (Mollusca: Gastropoda) exposed to chromium and water samples.

    PubMed

    Tallarico, Lenita de Freitas; Borrely, Sueli Ivone; Hamada, Natália; Grazeffe, Vanessa Siqueira; Ohlweiler, Fernanda Pires; Okazaki, Kayo; Granatelli, Amanda Tosatte; Pereira, Ivana Wuo; Pereira, Carlos Alberto de Bragança; Nakano, Eliana

    2014-12-01

    A protocol combining acute toxicity, developmental toxicity and mutagenicity analysis in freshwater snail Biomphalaria glabrata for application in ecotoxicological studies is described. For acute toxicity testing, LC50 and EC50 values were determined; dominant lethal mutations induction was the endpoint for mutagenicity analysis. Reference toxicant potassium dichromate (K2Cr2O7) was used to characterize B. glabrata sensitivity for toxicity and cyclophosphamide to mutagenicity testing purposes. Compared to other relevant freshwater species, B. glabrata showed high sensitivity: the lowest EC50 value was obtained with embryos at veliger stage (5.76mg/L). To assess the model applicability for environmental studies, influent and effluent water samples from a wastewater treatment plant were evaluated. Gastropod sensitivity was assessed in comparison to the standardized bioassay with Daphnia similis exposed to the same water samples. Sampling sites identified as toxic to daphnids were also detected by snails, showing a qualitatively similar sensitivity suggesting that B. glabrata is a suitable test species for freshwater monitoring. Holding procedures and protocols implemented for toxicity and developmental bioassays showed to be in compliance with international standards for intra-laboratory precision. Thereby, we are proposing this system for application in ecotoxicological studies. PMID:25259848

  6. Sensitizing potential of triclosan and triclosan-based skin care products in patients with chronic eczema.

    PubMed

    Schena, Donatella; Papagrigoraki, Anastasia; Girolomoni, Giampiero

    2008-10-01

    Triclosan is a lypophilic chlorophenol biocide with broad-spectrum antibacterial and antifungal activity. Triclosan-based topical products have been shown to be tolerated and beneficial in atopic dermatitis. The aim of this study was to evaluate the sensitizing potential of triclosan and triclosan-based creams in patients affected by eczematous dermatitis. Two hundred and seventy-five patients affected by chronic eczema (allergic contact dermatitis, irritant contact dermatitis, atopic eczema, nummular eczema, stasis dermatitis) were patch tested with standard patch test series as well as triclosan and triclosan-based products. Standard patch test series resulted positive in 164 patients (61%), with nickel sulfate, house dust mites, fragrance mix, propolis, thimerosal, myroxylon pereira, potassium dichromate, wool alcohols, and p-phenylenediamine the most common sensitizing haptens. Only two patients developed positive reactions to triclosan (0.7%) and four (1.4%) to triclosan-based products. The present study's results confirm that triclosan is well tolerated and has a very low sensitizing potential even in high-risk patients affected by eczema. PMID:18837732

  7. Sensitizations to allergens of TRUE test in 864 consecutive eczema patients in Israel.

    PubMed

    Magen, Eli; Mishal, Joseph; Schlesinger, Menachem

    2006-12-01

    The TRUE test is a widespread diagnostic tool for initial patch testing of patients with contact dermatitis (CD). From 2002 to 2005, 864 patients with eczema were patch-tested using TRUE test in one Israeli allergology clinic. 547 (63.3%) patients were female and 317 (36.7%) were male. 346 (40%) patients had > or =1 positive patch test reactions. The most common allergens were nickel sulfate for 114 (13.2%) patients, potassium dichromate 111 (12.8%), fragrance mix 59 (6.8%), cobalt chloride 12 (1.4%), ethylenediamine dihydrochloride 11 (1.3%), epoxy resin 11 (1.3%), balsam of Peru 9 (1.0%), carba mix 7 (0.8%), thiomersal 6 (0.7%), wool alcohol 5 (0.6%), black rubber (PPD) mix 5 (0.6%), neomycin 4 (0.5%); Kathon CG, Colophony and Quaternium 15 - each 2 (0.2%), other allergens - each 1 (0.1%). In male patients, carba mix, black rubber (PPD) mix and epoxy resin sensitivity was more frequent, whereas nickel sulfate, fragrance mix, ethylenediamine dihydrochloride and cobalt chloride sensitivity was significantly more frequent in female patients. Our results are in general agreement with previously published reports, excluding the low sensitivity rates to cobalt, which maybe is missed by TRUE test. PMID:17101019

  8. Contact sensitization in 1094 children undergoing patch testing over a 7-year period.

    PubMed

    Seidenari, Stefania; Giusti, Francesca; Pepe, Patrizia; Mantovani, Lucia

    2005-01-01

    Contact sensitization in children is frequent. However, because exposure to sensitizing agents varies rapidly, it is of utmost importance to perform a periodic evaluation of patch test results. Our purpose was to compare our data on contact sensitization in children during the past 7 years to our previous 1988-1994 findings, in order to identify emerging allergens and update our pediatric series. From 1995 to 2001, 1094 consecutive children were examined. Of these, 997 patients were patch tested with our pediatric series, which includes 30 allergens, whereas 97 underwent patch testing with 46 allergens. A total of 570 children proved allergic (52.1%). The highest sensitization rate was observed in children under 3 years of age. No differences between atopic dermatitis patients and nonatopic ones were observed in the sensitization rate. Neomycin, nickel, wool alcohols, thimerosal, and ammoniated mercury gave most of the positive responses. With respect to 1988-1995 data, allergy to substances such as neomycin, nickel, wool alcohols, thimerosal, ammoniated mercury, propolis, potassium dichromate, and thiuram mix proved more frequent. In conclusion, as sensitization rates to different allergens show great variations over time, periodic evaluations of patch test results in children is necessary in order to update the test trays. PMID:15660887

  9. Contact sensitization in chronic venous insufficiency: modern wound dressings.

    PubMed

    Gallenkemper, G; Rabe, E; Bauer, R

    1998-05-01

    Patch tests with an expanded European standard series and 20 different wound dressings revealed sensitization in 78% of all (36) patients. The charts of allergens were headed by ointment bases (wool wax alcohols sensitization in 33% of all patients; Amerchol L-101 19.4%; cetearyl alcohol 13.9%; propylene glycol 8.3%), followed by plant resins/ethereal oils (balsam of Peru 22.2%; colophony 13.9%, fragrance mix 8.3%; propolis 5.6%) and topical antibiotics (neomycin sulfate 16.7%, chloramphenicol 13.9%), while usually common sensitizers like metal salts were not found as often (nickel sulfate 16.7%; potassium dichromate 13.9%; cobalt chloride 5.6%). Sensitization to modern wound dressings was found in 8.3% (3 cases) and was caused by propylene glycol as an ingredient of hydrogels; no sensitization was found to hydrocolloids, alginates or polyurethane foams. The overall sensitization rate in 2nd degree CVI was nearly as high as in 3rd degree CVI, but sensitization to ointments, their additives and topical antibiotics was significantly higher in 3rd degree CVI. Significant differences in sensitization frequencies to individual allergens were found between male and female patients. Our investigation points out the high risk of sensitization in 2nd as well as 3rd degree CVI, especially to ointment bases and active principles of topical drugs. Even wound dressings may cause allergic contact reactions. PMID:9667445

  10. Ultrasound-promoted cold vapor generation in the presence of formic acid for determination of mercury by atomic absorption spectrometry.

    PubMed

    Gil, Sandra; Lavilla, Isela; Bendicho, Carlos

    2006-09-01

    A new cold vapor technique within the context of green chemistry is described for determination of mercury in liquid samples following high-intensity ultrasonication. Volatile Hg evolved in a sonoreactor without the use of a chemical reducing agent is carried to a quartz cell kept at room temperature for measurement of the atomic absorption. The mechanism involved lies in the reduction of Hg(II) to Hg(0) by reducing gases formed upon sonication and subsequent volatilization of Hg(0) due to the degassing effect caused by the cavitation phenomenon. Addition of a low molecular weight organic acid such as formic acid favors the process, but vapor generation also occurs from Hg solutions in ultrapure water. The detection limit of Hg was 0.1 microg/L, and the repeatability, expressed as relative standard deviation, was 4.4% (peak height). Addition of small amounts of oxidizing substances such as the permanganate or dichromate anions completely suppressed the formation of Hg(0), which confirms the above mechanism. Effect of other factors such as ultrasound irradiation time, ultrasound amplitude, and the presence of concomitants are also investigated. Some complexing anions such as chloride favored the stabilization of Hg(II) in solution, hence causing an interference effect on the ultrasound-assisted reduction/volatilization process. PMID:16944910

  11. Effect of Carbon and Energy Source on Bacterial Chromate Reduction

    SciTech Connect

    Smith, William Aaron; Apel, William Arnold; Petersen, J. N.; Peyton, Brent Michael

    2002-07-01

    Studies were conducted to evaluate carbon and energy sources suitable to support hexavalent chromium (Cr(VI)) reduction by a bacterial consortium enriched from dichromate-contaminated aquifer sediments. The consortium was cultured under denitrifying conditions in a minimal, synthetic groundwater medium that was amended with various individual potential carbon and energy sources. The effects of these individual carbon and energy sources on Cr(VI) reduction and growth were measured. The consortium was found to readily reduce Cr(VI) with sucrose, acetate, L-asparagine, hydrogen plus carbon dioxide, ethanol, glycerol, glycolate, propylene glycol, or D-xylose as a carbon and energy source. Minimal Cr(VI) reduction was observed when the consortium was cultured with citrate, 2-ketoglutarate, L-lactate, pyruvate, succinate, or thiosulfate plus carbon dioxide as a carbon and energy source when compared with abiotic controls. The consortium grew on all of the above carbon and energy sources, with the highest cell densities reached using D-xylose and sucrose, demonstrating that the consortium is metabolically diverse and can reduce Cr(VI) using a variety of different carbon and energy sources. The results suggest that the potential exists for the enrichment of Cr(VI)-reducing microbial populations in situ by the addition of a sucrose-containing feedstock such as molasses, which is an economical and readily available carbon and energy source.

  12. Effect of stubble burning on soil organic matter studied at a longterm experimental site

    NASA Astrophysics Data System (ADS)

    Normand, E.; Rumpel, C.; Mary, B.

    2009-04-01

    Stubble burning is a common agricultural practice in many regions of the world. It was frequently used in former times and is less applied nowerdays due to legal restrictions. Despite the importance of this practice, few studies were carried out to study its influence on soil organic matter. In general, the influence of fire on the global carbon cycle is not well understood. Using a longterm agricultural experiment to model C turnover, we discovered high amounts of stable carbon in the soil after 30 years of stubble burning. The aim of this study was to assess changes occurring in SOM composition following stubble burning. Soils were sampled from the longterm experiment "brûlage des pailles" at Issoudun en Champagne Berrichonne, which was carried out from 1962 to 1994. We sampled with three replicates soil which underwent continous stubble burning for 30 years, as well as a control soil, which did not receive this treatment. The samples were analysed for elemental and isotopic composition, acid dichromate resistant OC and acid hydrolysis resistant OC. After 30 years of stubble burning no significant change of the carbon content could be noticed in the carbon stock, whereas N-stocks were significantly depleted. After 30 years, stubble burning led to a reduction of mineral bound organic matter. This reduction is most enhanced for carbon compared to nitrogen and could indicate, that fire in the long-term affects SOM stabilisation mechanisms.

  13. The gas-liquid chromatograph and the electron capture detection in equine drug testing.

    PubMed Central

    Blake, J. W.; Tobin, T.

    1976-01-01

    Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four "esses" of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization. PMID:1000157

  14. Evaluation of Cajanus cajan (pigeon pea) for phytoremediation of landfill leachate containing chromium and lead.

    PubMed

    Jerez Ch, José A; Romero, Rosaura M

    2016-11-01

    Landfill leachates containing heavy metals are important contaminants and a matter of great concern due to the effect that they might have on ecosystems. We evaluated the use of Cajanus cajan to remove chromium and lead from landfill leachates. Eight-week-old plants were submitted to varied tests to select the experimental conditions. Water assays with a solution (pH 6) containing leachate (25% v/v) were selected; the metals were added as potassium dichromate and lead (II) nitrate salts. Soil matrices that contained leachate (30% v/v) up to field capacity were used. For both water and soil assays, the metal concentrations were 10 mg kg(-1). C. cajan proved able to remove 49% of chromium and 36% of lead, both from dilute leachate. The plants also removed 34.7% of chromium from irrigated soil, but were unable to decrease the lead content. Removal of nitrogen from landfill leachate was also tested, resulting in elimination of 85% of ammonia and 70% of combined nitrite/nitrate species. The results indicate that C. cajan might be an effective candidate for the rhizofiltration of leachates containing chromium and lead, and nitrogen in large concentrations. PMID:27196815

  15. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    NASA Astrophysics Data System (ADS)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  16. Histochemical and ultrastructural characterization of serotonin-containing cells in rabbit tracheal epithelium

    SciTech Connect

    Dey, R.D.; Shannon, W.A. Jr.; Hagler, H.K.; Said, S.I.

    1983-04-01

    Tracheal endocrine cells (TECs) that contain serotonin have been characterized previously by staining with ferric ferricyanide. In the present article, the ferric ferricyanide staining reaction has been used to locate the TECs in deplasticized thick sections of Epon-embedded rabbit tracheas. Adjacent thin sections of the same cell were subsequently observed by electron microscopy. The TECs were filled with dense-core vesicles (DCVs) located in the cytoplasm between the nucleus and the lumen and also lateral to the nucleus. In a separate experiment, pieces of rabbit trachea were treated with a solution of glutaraldehyde-dichromate to demonstrate the presence of amines. High levels of chromium were detected in the DCVs by energy-dispersive X-ray analysis. The results from these studies have correlated the ultrastructure of a serotonin-containing endocrine cell present in rabbit tracheal epithelium with a cell type previously characterized only by light and fluorescence histochemical methods. The results also indicate that serotonin in these cells is stored in the DCVs.

  17. Alternative Confidence Interval Methods Used in the Diagnostic Accuracy Studies

    PubMed Central

    Gülhan, Orekıcı Temel

    2016-01-01

    Background/Aim. It is necessary to decide whether the newly improved methods are better than the standard or reference test or not. To decide whether the new diagnostics test is better than the gold standard test/imperfect standard test, the differences of estimated sensitivity/specificity are calculated with the help of information obtained from samples. However, to generalize this value to the population, it should be given with the confidence intervals. The aim of this study is to evaluate the confidence interval methods developed for the differences between the two dependent sensitivity/specificity values on a clinical application. Materials and Methods. In this study, confidence interval methods like Asymptotic Intervals, Conditional Intervals, Unconditional Interval, Score Intervals, and Nonparametric Methods Based on Relative Effects Intervals are used. Besides, as clinical application, data used in diagnostics study by Dickel et al. (2010) has been taken as a sample. Results. The results belonging to the alternative confidence interval methods for Nickel Sulfate, Potassium Dichromate, and Lanolin Alcohol are given as a table. Conclusion. While preferring the confidence interval methods, the researchers have to consider whether the case to be compared is single ratio or dependent binary ratio differences, the correlation coefficient between the rates in two dependent ratios and the sample sizes. PMID:27478491

  18. Proposal of an in vivo comet assay using haemocytes of Drosophila melanogaster.

    PubMed

    Carmona, Erico R; Guecheva, Temenouga N; Creus, Amadeu; Marcos, Ricardo

    2011-03-01

    This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (γ-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of γ-irradiation (2, 4, and 8 Gγ). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment. PMID:20740640

  19. Aerosol assisted chemical vapor deposition using nanoparticle precursors: a route to nanocomposite thin films.

    PubMed

    Palgrave, Robert G; Parkin, Ivan P

    2006-02-01

    Gold nanoparticle and gold/semiconductor nanocomposite thin films have been deposited using aerosol assisted chemical vapor deposition (CVD). A preformed gold colloid in toluene was used as a precursor to deposit gold films onto silica glass. These nanoparticle films showed the characteristic plasmon absorption of Au nanoparticles at 537 nm, and scanning electron microscopic (SEM) imaging confirmed the presence of individual gold particles. Nanocomposite films were deposited from the colloid concurrently with conventional CVD precursors. A film of gold particles in a host tungsten oxide matrix resulted from co-deposition with [W(OPh)(6)], while gold particles in a host titania matrix resulted from co-deposition with [Ti(O(i)Pr)(4)]. The density of Au nanoparticles within the film could be varied by changing the Au colloid concentration in the original precursor solution. Titania/gold composite films were intensely colored and showed dichromism: blue in transmitted light and red in reflected light. They showed metal-like reflection spectra and plasmon absorption. X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis confirmed the presence of metallic gold, and SEM imaging showed individual Au nanoparticles embedded in the films. X-ray diffraction detected crystalline gold in the composite films. This CVD technique can be readily extended to produce other nanocomposite films by varying the colloids and precursors used, and it offers a rapid, convenient route to nanoparticle and nanocomposite thin films. PMID:16448130

  20. Healthy response from chromium survived pteridophytic plant-Ampelopteris prolifera with the interaction of mycorrhizal fungus-Glomus deserticola.

    PubMed

    Singh, Joginder; Kumar, Manoj; Vyas, Anil

    2014-01-01

    Interaction between arbuscular mycorrhizal fungus Glomus deserticola and pteridophytic member Ampelopteris prolifera was found abundant on entire growth level based on elemental composition and gaseous exchange as a potential remediation system for phytoextraction of chromium. Inoculated A. prolifera (AM) and non-inoculated A. prolifera (Non-AM) were supplied with two Cr species: 12 mmol of trivalent cation (Cr(+3)) [Cr(III)] and 0.1 mmol of divalent dichromate anion (Cr2O7(-2)) [Cr(VI)]. Both Cr species were found to be depressed in overall growth and inefficient stomatal conductance (g(s)) and net photosynthesis (NP). Mycorrhizal association was found to be natural scavenger of Cr toxicity as indicated by greater growth in plants exposed to Cr species, and increased gas exchange of Cr(III) treated plants. Though, chromium reduction resulted lower level of nitrogen (N), phosphorus (P), and potassium (K) but interestingly elevated the level of aluminum (Al), iron (Fe), and zinc (Zn) uptake in many folds which is the significance of sustainable growth of plant. PMID:24912233

  1. Histological Stains: A Literature Review and Case Study

    PubMed Central

    Alturkistani, Hani A; Tashkandi, Faris M; Mohammedsaleh, Zuhair M

    2016-01-01

    The history of histology indicates that there have been significant changes in the techniques used for histological staining through chemical, molecular biology assays and immunological techniques, collectively referred to as histochemistry. Early histologists used the readily available chemicals to prepare tissues for microscopic studies; these laboratory chemicals were potassium dichromate, alcohol and the mercuric chloride to harden cellular tissues. Staining techniques used were carmine, silver nitrate, Giemsa, Trichrome Stains, Gram Stain and Hematoxylin among others. The purpose of this research was to assess past and current literature reviews, as well as case studies, with the aim of informing ways in which histological stains have been improved in the modern age. Results from the literature review has indicated that there has been an improvement in histopathology and histotechnology in stains used. There has been a rising need for efficient, accurate and less complex staining procedures. Many stain procedures are still in use today, and many others have been replaced with new immunostaining, molecular, non-culture and other advanced staining techniques. Some staining methods have been abandoned because the chemicals required have been medically proven to be toxic. The case studies indicated that in modern histology a combination of different stain techniques are used to enhance the effectiveness of the staining process. Currently, improved histological stains, have been modified and combined with other stains to improve their effectiveness. PMID:26493433

  2. The mitigative effect of Raphanus sativus oil on chromium-induced geno- and hepatotoxicity in male rats

    PubMed Central

    Elshazly, M.O.; Morgan, Ashraf M.; Ali, Merhan E.; Abdel-mawla, Essam; Abd El-Rahman, Sahar S.

    2016-01-01

    To study the impact of radish oil on the possible genotoxic and hepatotoxic effects of hexavalent chromium, male rats were divided into 4 groups. Group 1 served as control, group 2 received radish oil at the recommended human therapeutic dose (0.07 mL/kg) by gavage, group 3 received sodium dichromate dihydrate (SDD) 520 mg/L in drinking water, and group 4 received both SDD and radish oil as previously mentioned in groups 2 and 3. All treatments were continued for six months. The results revealed that chromium exposure promoted oxidative stress with a consequently marked hepatic histopathological alterations, increased serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, alfa fetoprotein (AFP) levels, and micronucleated erythrocytes (MNE) % in peripheral blood. Moreover, COMET assay of hepatic DNA revealed that SDD exposure significantly decreased the intact cells %, head diameter, and head DNA % compared to control, indicating DNA damage. However, radish oil co-administration with SDD resulted in marked amendment in the altered parameters as detected by improved liver function markers (ALT and ALP) and AFP level, decreased lipid peroxidation, increased antioxidant markers, inhibited hepatic DNA damage and restored the hepatic histology by preventing the appearance of the altered hepatocytes’ foci and decreasing chromium induced histopathological lesions. It could be concluded that radish oil was able to provide a convergent complete protection against the geno- and hepatotoxicity of chromium by its potent antioxidant effect. PMID:27222746

  3. Removal of Cr(VI) from Aqueous Solutions Using Powder of Potato Peelings as a Low Cost Sorbent.

    PubMed

    Mutongo, Farai; Kuipa, Olga; Kuipa, Pardon K

    2014-01-01

    Potato peels which are a low cost, renewable agroindustry by-product were used for the removal of hexavalent chromium from aqueous effluents. Batch experiments were carried out with an artificial effluent comprising of potassium dichromate in deionised water. The effects of the initial hexavalent chromium concentration, dose of biosorbent, and removal kinetics were explored. An adsorbent dosage of 4 g/L was effective in complete removal of the metal ion, at pH 2.5, in 48 minutes. The kinetic process of Cr(VI) adsorption onto potato peel powder was tested by applying pseudo-first-order and pseudo-second-order models as well as the Elovich kinetic equation to correlate the experimental data and to determine the kinetic parameters. The adsorption data were correlated by the Langmuir and Freundlich isotherms. A maximum monolayer adsorption capacity of 3.28 mg/g was calculated using the Langmuir adsorption isotherm, suggesting a functional group limited adsorption process. The results confirmed that potato peels are an effective biosorbent for the removal of hexavalent chromium from effluent. PMID:25136289

  4. Effect of oxidizing adulterants on human urinary steroid profiles.

    PubMed

    Kuzhiumparambil, Unnikrishnan; Fu, Shanlin

    2013-02-01

    Steroid profiling is the most versatile and informative technique adapted by doping control laboratories for detection of steroid abuse. The absolute concentrations and ratios of endogenous steroids including testosterone, epitestosterone, androsterone, etiocholanolone, 5α-androstane-3α,17β-diol and 5β-androstane-3α,17β-diol constitute the significant characteristics of a steroid profile. In the present study we report the influence of various oxidizing adulterants on the steroid profile of human urine. Gas chromatography-mass spectrometry analysis was carried out to develop the steroid profile of human male and female urine. Oxidants potassium nitrite, sodium hypochlorite, potassium permanganate, cerium ammonium nitrate, sodium metaperiodate, pyridinium chlorochromate, potassium dichromate and potassium perchlorate were reacted with urine at various concentrations and conditions and the effect of these oxidants on the steroid profile were analyzed. Most of the oxidizing chemicals led to significant changes in endogenous steroid profile parameters which were considered stable under normal conditions. These oxidizing chemicals can cause serious problems regarding the interpretation of steroid profiles and have the potential to act as masking agents that can complicate or prevent the detection of the steroid abuse. PMID:23238517

  5. Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Idehara, Toshitaka; Fukazawa, Jun; Fujiwara, Toshimichi

    2016-03-01

    Sensitivity enhancement of MAS NMR using dynamic nuclear polarization (DNP) is gaining importance at moderate fields (B0 < 9 T) and temperatures (T > 90 K) with potential applications in chemistry and material sciences. However, considering the ever-increasing size and complexity of the systems to be studied, it is crucial to establish DNP under higher field conditions, where the spectral resolution and the basic NMR sensitivity tend to improve. In this perspective, we overview our recent efforts on hardware developments, specifically targeted on improving DNP MAS NMR at high fields. It includes the development of gyrotrons that enable continuous frequency tuning and rapid frequency modulation for our 395 GHz-600 MHz and 460 GHz-700 MHz DNP NMR spectrometers. The latter 700 MHz system involves two gyrotrons and a quasi-optical transmission system that combines two independent sub-millimeter waves into a single dichromic wave. We also describe two cryogenic MAS NMR probe systems operating, respectively, at T ∼100 K and ∼30 K. The latter system utilizes a novel closed-loop helium recirculation mechanism, achieving cryogenic MAS without consuming any cryogen. These instruments altogether should promote high-field DNP toward more efficient, reliable and affordable technology. Some experimental DNP results obtained with these instruments are presented.

  6. Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures.

    PubMed

    Matsuki, Yoh; Idehara, Toshitaka; Fukazawa, Jun; Fujiwara, Toshimichi

    2016-03-01

    Sensitivity enhancement of MAS NMR using dynamic nuclear polarization (DNP) is gaining importance at moderate fields (B0<9T) and temperatures (T>90K) with potential applications in chemistry and material sciences. However, considering the ever-increasing size and complexity of the systems to be studied, it is crucial to establish DNP under higher field conditions, where the spectral resolution and the basic NMR sensitivity tend to improve. In this perspective, we overview our recent efforts on hardware developments, specifically targeted on improving DNP MAS NMR at high fields. It includes the development of gyrotrons that enable continuous frequency tuning and rapid frequency modulation for our 395 GHz-600 MHz and 460 GHz-700 MHz DNP NMR spectrometers. The latter 700 MHz system involves two gyrotrons and a quasi-optical transmission system that combines two independent sub-millimeter waves into a single dichromic wave. We also describe two cryogenic MAS NMR probe systems operating, respectively, at T ∼ 100K and ∼ 30K. The latter system utilizes a novel closed-loop helium recirculation mechanism, achieving cryogenic MAS without consuming any cryogen. These instruments altogether should promote high-field DNP toward more efficient, reliable and affordable technology. Some experimental DNP results obtained with these instruments are presented. PMID:26920836

  7. Laser-induced breakdown spectroscopy (LIBS) to measure quantitatively soil carbon with emphasis on soil organic carbon. A review.

    PubMed

    Senesi, Giorgio S; Senesi, Nicola

    2016-09-28

    Soil organic carbon (OC) measurement is a crucial factor for quantifying soil C pools and inventories and monitoring the inherent temporal and spatial heterogeneity and changes of soil OC content. These are relevant issues in addressing sustainable management of terrestrial OC aiming to enhance C sequestration in soil, thus mitigating the impact of increasing CO2 concentration in the atmosphere and related effects on global climate change. Nowadays, dry combustion by an elemental analyzer or wet combustion by dichromate oxidation of the soil sample are the most recommended and commonly used methods for quantitative soil OC determination. However, the unanimously recognized uncertainties and limitations of these classical laboursome methods have prompted research efforts focusing on the development and application of more advanced and appealing techniques and methods for the measurement of soil OC in the laboratory and possibly in situ in the field. Among these laser-induced breakdown spectroscopy (LIBS) has raised the highest interest for its unique advantages. After an introduction and a highlight of the LIBS basic principles, instrumentation, methodologies and supporting chemometric methods, the main body of this review provides an historical and critical overview of the developments and results obtained up-to-now by the application of LIBS to the quantitative measurement of soil C and especially OC content. A brief critical summary of LIBS advantages and limitations/drawbacks including some final remarks and future perspectives concludes this review. PMID:27619082

  8. A bioelectrochemical reactor containing carbon fiber textiles enables efficient methane fermentation from garbage slurry.

    PubMed

    Sasaki, Kengo; Morita, Masahiko; Sasaki, Daisuke; Hirano, Shin-ichi; Matsumoto, Norio; Watanabe, Atsushi; Ohmura, Naoya; Igarashi, Yasuo

    2011-07-01

    A packed-bed system includes supporting materials to retain microorganisms and a bioelectrochemical system influences the microbial metabolism. In our study, carbon fiber textiles (CFT) as a supporting material was attached onto a carbon working electrode in a bioelectrochemical reactor (BER) that degrades garbage slurry to methane, in order to investigate the effect of combining electrochemical regulation and packing CFT. The potential on the working electrode in the BER containing CFT was set to -1.0 V or -0.8 V (vs. Ag/AgCl). BERs containing CFT exhibited higher methane production, elimination of dichromate chemical oxygen demand, and the ratio of methanogens in the suspended fraction than reactors containing CFT without electrochemical regulation at an organic loading rate (OLR) of 27.8 gCODcr/L/day. In addition, BERs containing CFT exhibited higher reactor performances than BERs without CFT at this OLR. Our results revealed that the new design that combined electrochemical regulation and packing CFT was effective. PMID:21550235

  9. Construction of hydrogen fermentation from garbage slurry using the membrane free bioelectrochemical system.

    PubMed

    Sasaki, Kengo; Morita, Masahiko; Matsumoto, Norio; Sasaki, Daisuke; Hirano, Shin-ichi; Ohmura, Naoya; Igarashi, Yasuo

    2012-07-01

    The aim of this study was to show the effectiveness of the membrane free bioelectrochemical system (BES) using three electrodes on inhibition of methanogenesis and construction of hydrogen fermentation from the artificial garbage slurry. The electrical redox-potential on the working electrode was adjusted to -1.0V (vs. Ag/AgCl) that has positive effect on methanogenesis. The redox-potential on the counter electrode was measured to be 1.6V. The pH in the effluents was 5.5-6.4. Hydrogen production rate at the cathode side was similar to that at the anode side and much higher than that calculated from current, and reached a maximum of 2445±815 (average±standard deviation) mL L(-1) d(-1) at an organic loading rate of 58.7g dichromate chemical oxygen demand per L d(-1). Methane production was negligible throughout the experiment. Acetate and butyrate were the main products of the fermentation using a BES; these offered favorable conditions for hydrogen production. The bacterial community in the bioelectrochemical hydrogen fermentor differed from that in the methanogenic seed sludge and included hitherto unknown species. These results show that high redox-potential on the anodic electrode and acidic pH in the membrane free BES can be utilized for hydrogen fermentation from the artificial garbage slurry by avoiding methanogenesis. PMID:22571961

  10. Effect of adding carbon fiber textiles to methanogenic bioreactors used to treat an artificial garbage slurry.

    PubMed

    Sasaki, Kengo; Morita, Masahiko; Hirano, Shin-Ichi; Ohmura, Naoya; Igarashi, Yasuo

    2009-08-01

    To compare the performances and microbial populations of methanogenic reactors with and without carbon fiber textiles (CFT), we operated small-scale (200 ml) reactors using a slurry of artificial garbage. For both types of reactors, the organic loading rate (OLR) was stepwisely and rapidly increased in the same manner. Start-up period was shortened by adding CFT. Reactors with CFT showed greater efficiency for removal of suspended solid and volatile suspended solid than reactors without CFT at a long hydraulic retention time (HRT) between 8 and 13 days. The reactors with CFT maintained stable methane production at an OLR of 15.3 g dichromate chemical oxygen demand (CODcr)/l/day and DNAs from microorganisms were highly concentrated in adhering fractions on CFT. As shown by quantitative PCR analysis, the proportions of methanogenic archaea were conserved more than 25% in adhering fractions on CFT in reactors with CFT. By contrast, reactors without CFT showed accumulation of volatile fatty acid and deteriorated at an OLR of 2.4 gCODcr/l/day. Methanogenic proportions dropped to 17.1% in suspended fractions of reactors without CFT. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that all archaeal DGGE bands in both types of reactors were related to methanogens, but more bands were observed in reactors with CFT. Thus the higher performance of reactors with CFT likely reflects the greater abundance of microorganisms and methanogenic diversity. PMID:19619860

  11. Bioelectrochemical system stabilizes methane fermentation from garbage slurry.

    PubMed

    Sasaki, Kengo; Sasaki, Daisuke; Morita, Masahiko; Hirano, Shin-Ichi; Matsumoto, Norio; Ohmura, Naoya; Igarashi, Yasuo

    2010-05-01

    Methanogenic bioreactors, which are packed with supporting material, have attracted attention as an efficient means of degrading garbage. We aimed to increase bioreactor performance by using an electrochemical system to regulate the electrical potential on supporting material. At an organic loading rate of 26.9g dichromate chemical oxygen demand (CODcr)/L/day, reactors with a potential of -0.6 or -0.8V, generated by a cathodic electrochemical reaction, showed greater removal of CODcr and methanogenesis than reactors with a potential of 0.0 or -0.3V, generated by anodic reaction, or control reactors without electrochemical regulation. 16S rRNA gene analysis revealed that the same methanogens were present in all our reactors, but quantitative real-time polymerase chain reaction showed that higher prokaryotic and methanogenic copy numbers were present on cathodic electrodes than on anodic or control electrodes. These results indicate that cathodic electrochemical regulation can support methane fermentation from garbage. PMID:20074940

  12. The role of mitochondria in chromium carcinogenesis

    SciTech Connect

    Rossi, S.C. )

    1987-01-01

    The uptake and reduction of chromium(VI) compounds are crucial to their carcinogenicity. Many cellular systems have been shown to reduce chromium(VI). The ability of mitochondria to reduce chromate in vitro was investigated using rat liver submitochondrial particles (SMPs), which contain the electron transport chain, and isolated rat liver mitochondria. SMPs with NADH as substrate reduced chromate as shown by EPR and UV-VIS spectroscopic studies. Chromate was reduced to a chromium(V) species, which was detectable by EPR. SMPs with succinate as substrate were less effective in reducing chromate relative to NADH-driven chromate-reductase activity. SMPs show a higher rate of oxygen depletion with NADH as substrate as compared to succinate as substrate. In SMPs with NADH as substrate, rotenone, antimycin and cyanide all produced a {approx}40% inhibition of chromate-reductase activity. In SMPs with succinate as substrate, cyanide and antimycin produced {approx}50% inhibition of chromate-reductase activity and rotenone caused no detectable inhibition. In vivo studies of rats injected with sodium dichromate spiked with {sup 51}Cr showed that after 24 hr, chromium was bound preferentially to mitochondrial DNA relative to nuclear DNA by a factor of {approximately}1500.

  13. Chromium stress induced alterations in biochemical and enzyme metabolism in aquatic and terrestrial plants.

    PubMed

    Ganesh, K Sankar; Baskaran, L; Rajasekaran, S; Sumathi, K; Chidambaram, A L A; Sundaramoorthy, P

    2008-06-01

    Water is seriously polluted by the discharge of various industrial wastewater containing heavy metals. Among them, chromium is considered to be toxic to living organisms and it is released mostly from tanneries. The chromium-contaminated water is discharged into nearby water bodies and it affects both aquatic and terrestrial plants. So the present experiment was conducted with an aquatic plant, water lettuce (Pistia stratiotes L.) and a terrestrial plant soybean (Glycine max L. Merr.). They were treated with different concentrations (0, 5, 10, 25, 50, 100 and 200mg/L) of potassium dichromate solution. The biochemical parameters such as total chlorophyll, carotenoid, protein and amino acid content and the enzymatic activities like catalase and peroxidase were estimated. The accumulation of chromium was also analysed in both the plants. All the biochemical contents and enzyme activities of water lettuce and soybean seedlings showed a great variation with respect to the increase in chromium concentrations. The accumulation of chromium increased gradually with the increase of chromium concentrations. Total inhibition of all the parameters were observed at 300 mg/L chromium concentration. The terrestrial plant soybean was sensitive than the aquatic plant water lettuce towards chromium stress. PMID:18206355

  14. Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

    PubMed

    Mahajan, Rakesh Kumar; Kaur, Ravneet; Kaur, Inderpreet; Sharma, Vandana; Kumar, Manoj

    2004-05-01

    A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. PMID:15171285

  15. A miniature photoelectrochemical sensor based on organic electrochemical transistor for sensitive determination of chemical oxygen demand in wastewaters.

    PubMed

    Liao, Jianjun; Lin, Shiwei; Zeng, Min; Yang, Yue

    2016-05-01

    A three-electrode configuration is often required in the conventional photoelectrochemical measurements. Nevertheless, one common drawback is the reference electrode and the counter electrode used in the measurements, which has been proved to be an impediment for the miniaturization. In this study, a simple, cost-effective and miniature photoelectrochemical sensor based on high sensitive organic electrochemical transistor (OECT) is developed and used for the determination of chemical oxygen demand (COD) in wastewaters. The devices show detection limit down to 0.01 mg/L COD, which is two orders of magnitude better than that of the conventional photoelectrochemical method. The excellent sensing performance can be contributed to the novel sensing mechanism of OECT devices. That is, the devices are sensitive to the potential changes induced by the photoelectrochemical reaction on TiO2 nanotube arrays gate electrodes. Real sample analyses are also carried out. The results demonstrate that the measured COD values using the OECT devices and the standard dichromate methods are in a good agreement. Since the proposed sensor is constructed on a miniature transistor, it is expected that the device shows a promising application on the integrated COD monitoring platform. PMID:26971805

  16. Disruption of putrescine biosynthesis in Shewanella oneidensis enhances biofilm cohesiveness and performance in Cr(VI) immobilization.

    PubMed

    Ding, Yuanzhao; Peng, Ni; Du, Yonghua; Ji, Lianghui; Cao, Bin

    2014-02-01

    Although biofilm-based bioprocesses have been increasingly used in various applications, the long-term robust and efficient biofilm performance remains one of the main bottlenecks. In this study, we demonstrated that biofilm cohesiveness and performance of Shewanella oneidensis can be enhanced through disrupting putrescine biosynthesis. Through random transposon mutagenesis library screening, one hyperadherent mutant strain, CP2-1-S1, exhibiting an enhanced capability in biofilm formation, was obtained. Comparative analysis of the performance of biofilms formed by S. oneidensis MR-1 wild type (WT) and CP2-1-S1 in removing dichromate (Cr2O7(2-)), i.e., Cr(VI), from the aqueous phase showed that, compared with the WT biofilms, CP2-1-S1 biofilms displayed a substantially lower rate of cell detachment upon exposure to Cr(VI), suggesting a higher cohesiveness of the mutant biofilms. In addition, the amount of Cr(III) immobilized by CP2-1-S1 biofilms was much larger, indicating an enhanced performance in Cr(VI) bioremediation. We further showed that speF, a putrescine biosynthesis gene, was disrupted in CP2-1-S1 and that the biofilm phenotypes could be restored by both genetic and chemical complementations. Our results also demonstrated an important role of putrescine in mediating matrix disassembly in S. oneidensis biofilms. PMID:24362428

  17. Chromium-VI arrests cell cycle and decreases granulosa cell proliferation by down-regulating cyclin-dependent kinases (CDK) and cyclins and up-regulating CDK-Inhibitors

    PubMed Central

    Stanley, Jone A.; Lee, JeHoon; Nithy, Thamizh K.; Arosh, Joe A.; Burghardt, Robert C.; Banu, Sakhila K.

    2011-01-01

    Environmental contamination with hexavalent chromium (CrVI) has been increasing in the drinking water of the USA and developing countries. CrVI causes various health problems including menstrual disorders and infertility. Recently, we reported that CrVI causes granulosa cell apoptosis through the intrinsic apoptotic pathway. Our previous studies showed that postnatal exposure to CrVI arrests follicle development. In order to explore the underlying mechanism, primary and immortalized granulosa cells from rats were treated with 10 μM potassium dichromate and analyses of the cell cycle, and cell cycle regulatory proteins were performed. CrVI decreased cell proliferation as a result of cell cycle arrest and down-regulated cyclin-dependent kinases (CDK), cyclins, and PCNA while up-regulating CDK-inhibitors and down-regulating FSH receptor and ERβ. Vitamin C mitigated the effects of CrVI. This study shows that CrVI causes cell cycle arrest in granulosa cells by altering cell cycle regulatory proteins with potential intervention by vitamin C. PMID:21621607

  18. A Microfluidic Device for Continuous Sensing of Systemic Acute Toxicants in Drinking Water

    PubMed Central

    Zhao, Xinyan; Dong, Tao

    2013-01-01

    A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety. PMID:24300075

  19. Critical assessment of the formation of hydrogen peroxide in dough by fermenting yeast cells.

    PubMed

    Rezaei, Mohammad N; Dornez, Emmie; Verstrepen, Kevin J; Courtin, Christophe M

    2015-02-01

    Fermentation of bread dough leads to strengthening of the dough matrix. This effect has previously been ascribed to the action of hydrogen peroxide (H2O2) produced by yeast in dough. In this study, we re-evaluate the production of H2O2 by yeast in dough and aqueous fermentation broth. Results show that the previously reported high levels of H2O2 in fermenting dough were most probably due to the lack of specificity of the potassium dichromate/acetic acid-based method used. Using the chemiluminescent HyPerBlu assay, no yeast H2O2 production could be detected in fermented dough or broth. Even though the formation of low levels of H2O2 cannot be ruled out due to the presence of catalase in flour and the fast reaction of H2O2 with gluten proteins, our results suggest that the changes in dough matrix rheological properties upon fermentation are not due to production of H2O2 by yeast. PMID:25172698

  20. Genotoxicity is modulated by ascorbic acid. Studies using the wing spot test in Drosophila.

    PubMed

    Kaya, Bülent; Creus, Amadeu; Velázquez, Antonia; Yanikoğlu, Atila; Marcos, Ricardo

    2002-09-26

    The ability of ascorbic acid (Vitamin C) to modulate the genotoxic action of several mutagens was investigated in the wing spot test of Drosophila melanogaster. In this assay, 3-day-old transheterozygous larvae for the multiple wing hairs (mwh, 3-0.3) and flare (flr, 3-38.8) genes were treated with three reference mutagenic compounds, namely cobalt chloride (CoCl2), 4-nitroquinoline 1-oxide (4-NQO) and potassium dichromate (K2Cr2O7). The results obtained show that the three reference mutagens tested were clearly genotoxic in the Drosophila wing somatic mutation and recombination test (SMART). None of the three concentrations tested of ascorbic acid (25, 75 and 250mM) induced significant increases in the frequency of the mutant clones recorded. When co-treatment experiments with ascorbic acid were carried out, different results were found. Thus, ascorbic acid was effective in reducing the genotoxicity of K2Cr2O7 virtually to the control level; on the contrary, it did not show any antigenotoxic effect on the genotoxicity of 4-NQO. Finally, co-treatments with CoCl2 and ascorbic acid show a significant increase in the frequency of mutant clones over the values obtained with CoCl2 alone. PMID:12297148

  1. Determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions by potentiometric titration

    SciTech Connect

    Tucker, H.L.; McElhaney, R.J.

    1983-01-01

    A simple, fast method for the determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions has been adapted from the Davies-Gray volumetric method to meet the needs of Y-12. One-gram duplicate aliquots of uranium metal or uranium oxide are dissolved in 1:1 HNO/sub 3/ and concentrated H/sub 2/SO/sub 4/ to sulfur trioxide fumes, and then diluted to 100-mL volume. Duplicate aliquots are then weighed for analysis. For uranyl nitrate samples, duplicate aliquots containing between 50 and 150 mg of U are weighed and analyzed directly. The weighed aliquot is transferred to a Berzelius beaker; 1.5 M sulfamic acid is added, followed in order by concentrated phosphoric acid, 1 M ferrous sulfate, and (after a 30-second interval) the oxidizing reagent. After a timed 3-minute waiting period, 100 mL of the 0.1% vanadyl sulfate-sulfuric acid mixture is added. The sample is then titrated past its endpoint with standard potassium dichromate, and the endpoint is determined by second derivative techniques on a mV/weight basis.

  2. The Remedial Efficacy of Spirulina platensis versus Chromium-Induced Nephrotoxicity in Male Sprague-Dawley Rats.

    PubMed

    Elshazly, M O; Abd El-Rahman, Sahar S; Morgan, Ashraf M; Ali, Merhan E

    2015-01-01

    This study was conducted to investigate the possible protective effect of Spirulina platensis against chromium-induced nephrotoxicity. A total of 36 adult male Sprague-Dawley rats were divided into 4 equal groups (Gps). Gp1 served as control, rats of Gps 2, 3, and 4 were exposed to Spirulina platensis (300 mg/kg b.wt per os) and sodium dichromate dihydrate (SDD) via drinking water at concentration of 520 mg /l respectively. Chromium administration caused alterations in the renal function markers as evidenced by significant increase of blood urea and creatinine levels accompanied with significant increase in kidney's chromium residues and MDA level as well as decreased catalase activity and glutathion content in kidney tissue. Histologically, Cr provoked deleterious changes including: vascular congestion, wide spread tubular epithelium necrobiotic changes, atrophy of glomerular tuft and proliferative hyperplasia. The latter was accompanied with positive PCNA expression in kidney tissues as well as DNA ploidy interpretation of major cellular population of degenerated cells, appearance of tetraploid cells, high proliferation index and high DNA index. Morphometrical measurements revealed marked glomerular and tubular lumen alterations. On contrary, spirulina co-treatment with Cr significantly restored the histopathological changes, antioxidants and renal function markers and all the previously mentioned changes as well. PMID:26029926

  3. Microspectrofluorometric study of monoamines in the auricle of the heart of Protopterus aethiopicus.

    PubMed

    Scheuermann, D W; Stilman, C; Reinhold, C; De Groodt-Lasseel, M H

    1981-01-01

    The auricle of the heart of Protopterus aethiopicus contains large numbers of chromaffin cells, often lying immediately adjacent to the endothelium and displaying a bright blue-white fluorescence characteristic for catecholamines after formaldehyde treatment (Falck and Owman 1965). These results combined with X-ray microanalysis after initial fixation with glutaraldehyde and subsequent treatment with dichromate established that these chromaffin cells are the storage site of primary catecholamines (Scheuermann 1978, 1979, 1980; Scheuermann et al. 1980). The aim of the present pilot study was to demonstrate in these cells noradrenaline (NA) or dopamine (DA), or a mixture of both. The evaluation of the excitation spectra of the catecholamine fluorophore transformed by treatment with HCl vapour (excitation maxima at 320 and 370 nm) and the excitation-peak ratio analysis (peak ratio 370/320 nm = 1.05-1.5; and 320/280 nm greater than 1.5) identify DA as the primary catecholamine stored in these chromaffin cells. The low fading rate of the monoamine fluorescence after acidification confirms the presence of DA. These microspectrofluorometric findings demonstrate that chromaffin cells in the auricle of the Protopterus heart, which are a part of the medullary homologue of the adrenal gland of higher vertebrates, contain a primary catecholamine, namely DA. PMID:7237540

  4. Oxidative stress and hypermethylation induced by exposure of Oreochromis niloticus to complex environmental mixtures of river water from Cubatão do Sul, Brazil.

    PubMed

    Fuzinatto, Cristiane Funghetto; Flohr, Letícia; Melegari, Sílvia Pedroso; Matias, William Gerson

    2015-04-01

    In this study, we investigated the effects of oxidative stress and hypermethylation through lipid peroxidation and DNA methylation, respectively, in erythrocytes of Oreochromis niloticus exposed to environmental complex mixture of water from Cubatão do Sul River throughout the year. This river is the source of drinking water for the region of Florianópolis, the capital of Santa Catarina State, Brazil. Lipid peroxidation was quantified by the rate of malondialdehyde (MDA) formation, and DNA methylation was quantified by the rate of 5-methyldeoxycytosine (m(5)dC) formation. In all studied sites, the river water samples caused metabolic changes in O. niloticus. MDA formation rates were significantly different when compared to the negative control (except for samples from Site 1 during spring 2010, summer 2011 and fall 2011). All samples (except Site 1, spring 2010) induced increases in the m(5)dC formation rates, and at the end of the study, the values were near the values found in the positive control (potassium dichromate 2.5mg/L). The results showed that samples of environmental complex mixtures of water from Cubatão do Sul River are capable of inducing high levels of oxidative damage and hypermethylation in O. niloticus. PMID:25638525

  5. Demonstration of multifunctional DNBM corrosion inhibitors in protective coatings for Naval Air/Weapon Systems. Final report, September 1989-July 1992

    SciTech Connect

    Bailin, L.J.

    1993-12-01

    The corrosion protective properties of multifunctional DNBM salts (quaternary ammonium dichromate, nitrate, borate, and molybdate) have been demonstrated on high-strength steel and aluminum alloys found in prototype aerospace weapon systems. The 100% DNBM mixture added to MIL-P-23377 epoxy-polyamide, minus strontium chromate inhibitor, on bare 7075-T6 aluminum alloy resisted 1000 h ASTM B-117 salt spray. However, the coatings were not resistant to hydraulic fluid immersion at the higher concentrations required for the corrosion inhibition. Microencapsulation of the reactive DNBM mixture was adopted as a means to prevent this susceptibility, as well as the destructive oxidation of the hydroxyl groups in the epoxy resin during cure. In the scale-up operation, approximately 20 gallons of DNBM weighing 64 kg (141 lb) was prepared from the four starting quarternary salts synthesized in a chemical process pilot plant. The salts were mixed by dissolving in toluene. Following removal of solvent, the resultant dark-brown liquid, approximating molasses in viscosity, was microencapsulated by the following method: The DNBM was dispersed to form an oil-in-water emulsion in an aqueous colloidal solution of low-viscosity, high-purity methyl cellulose using a Gifford-Wood homogenizer, followed by spray drying in an Anhydro spray dryer. The maximum practicable payload was 75% DNBM. After spray drying, the capsules Corrosion inhibitors, DNBM, Microencapsulation, Epoxy primers, Protective coatings.

  6. Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation.

    PubMed

    Veselská, Veronika; Fajgar, Radek; Číhalová, Sylva; Bolanz, Ralph M; Göttlicher, Jörg; Steininger, Ralph; Siddique, Jamal A; Komárek, Michael

    2016-11-15

    This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3-10), ionic strengths (0.001-0.1M KNO3), sorbate concentrations (10(-4), 10(-5), and 10(-6)M Cr(VI)), and sorbate/sorbent ratios (50-500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes. PMID:27450335

  7. Effect of hexavalent chromium-treated sperm on in vitro fertilization and embryo development.

    PubMed

    Yoisungnern, Ton; Das, Joydeep; Choi, Yun-Jung; Parnpai, Rangsun; Kim, Jin-Hoi

    2016-09-01

    Hexavalent chromium (Cr(VI)) is an environmental contaminant that is associated with reproductive abnormalities in both humans and animals. In the present study, we evaluated the cytotoxic effect of Cr(VI) on sperm function and subsequent embryo development after in vitro fertilization (IVF). Sperm obtained from BDF1 male mice were treated with potassium dichromate (0, 3.125, 6.25, 12.5, 25, or 50 μM) for 3 h. Cr(VI) significantly decreased sperm viability and acrosome reaction with increasing dose. These Cr(VI)-treated sperms were further used for IVF of oocytes obtained from BDF1 female mice. Results showed that Cr(VI)-treated sperm caused a significant reduction in IVF success, higher developmental arrest at the two-cell stage of embryos, and delayed blastocyst formation with increasing dose. In particular, most blastocysts from the Cr(VI)-treated sperm resulted in hatching failure as well as decreased inner cell mass and trophectoderm (TE). Furthermore, blastocysts obtained from Cr(VI)-treated sperm showed lower expression of not only TE-associated genes (eomes, cdx2, and krt8) but also pluripotent marker genes (sox2, pou5f1, and klf4) that are responsible for further embryo development of blastocyst embryos. The results of our current study showed that Cr(VI)-treated sperm had negative effects on oocyte fertilization and subsequent embryo development. PMID:25903088

  8. Molecular characterization of Cryptosporidium spp. from fecal samples of birds kept in captivity in Brazil.

    PubMed

    Nakamura, Alex Akira; Simões, Daniel Castendo; Antunes, Rômulo Godik; da Silva, Deuvânia Carvalho; Meireles, Marcelo Vasconcelos

    2009-12-01

    The aim of this study was to determine the prevalence of Cryptosporidium species and genotypes in birds kept in captivity in Brazil. A total of 966 samples from 18 families of birds was collected and stored in 5% potassium dichromate solution at 4 degrees C until processing. Oocysts were purified in Sheather sugar solution following extraction of genomic DNA. Molecular analyses were performed using nested-PCR for amplification of fragments of the 18S subunit of rRNA gene and of the actin gene. Amplification of Cryptosporidium DNA fragments was obtained in 47 (4.86%) samples. Sequencing of amplified fragments and phylogenetic analyses allowed the identification of Cryptosporidium baileyi in a black vulture (Coragyps atratus), a domestic chicken (Gallus gallus domesticus) and a saffron finch (Sicalis flaveola); Cryptosporidium galli in canaries (Serinus canaria), a cockatiel (Nymphicus hollandicus) and lesser seed-finches (Oryzoborus angolensis); Cryptosporidium meleagridis in a domestic chicken (G. g. domesticus); Cryptosporidium parvum in a cockatiel (N. hollandicus); Cryptosporidium avian genotype I in a canary (S. canaria) and an Indian peafowl (Pavo cristatus); Cryptosporidium avian genotype II in ostriches (Struthio camelus) and Cryptosporidium avian genotype III in a cockatiel (N. hollandicus) and a peach-faced lovebird (Agapornis roseicolis). PMID:19683397

  9. Preparation of explosive nanoparticles in a porous chromium(III) oxide matrix: a first attempt to control the reactivity of explosives.

    PubMed

    Comet, M; Siegert, B; Pichot, V; Gibot, P; Spitzer, D

    2008-07-16

    This paper reports the first attempt to control the combustion and the detonation properties of a high explosive through its structure. A porous chromium(III) oxide matrix produced by the combustion of ammonium dichromate was infiltrated by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The structure of the Cr(2)O(3) matrix was studied by both scanning and transmission electron microscopy (SEM, TEM); the Cr(2)O(3)/RDX nanocomposites were characterized by nitrogen adsorption. A mathematical model based on these techniques was used to demonstrate that the Cr(2)O(3) matrix encloses and stabilizes RDX particles at the nanoscale. The decomposition process of the nanocomposites was investigated by atomic force microscopy (AFM). The reactivity and sensitivity of the nanocomposites were studied by impact and friction tests, differential scanning calorimetry (DSC), time-resolved cinematography and detonation experiments, and were correlated with their structure. The size of RDX nanoparticles and their distribution in the Cr(2)O(3) matrix have an important influence on their reactivity. The reactive properties of nanostructured RDX differ significantly from those of classical micron-sized RDX. For instance, the melting point disappears and the decomposition temperature is significantly lowered. The quantization of the explosive particles in the Cr(2)O(3) matrix decreases the sensitivity to mechanical stress and allows controlling the decomposition mode-i.e. combustion versus detonation. PMID:21828750

  10. Viral-templated Palladium Nanocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Cuixian

    Despite recent progress on nanocatalysis, there exist several critical challenges in simple and readily controllable nanocatalyst synthesis including the unpredictable particle growth, deactivation of catalytic activity, cumbersome catalyst recovery and lack of in-situ reaction monitoring. In this dissertation, two novel approaches are presented for the fabrication of viral-templated palladium (Pd) nanocatalysts, and their catalytic activities for dichromate reduction reaction and Suzuki Coupling reaction were thoroughly studied. In the first approach, viral template based bottom-up assembly is employed for the Pd nanocatalyst synthesis in a chip-based format. Specifically, genetically displayed cysteine residues on each coat protein of Tobacco Mosaic Virus (TMV) templates provide precisely spaced thiol functionalities for readily controllable surface assembly and enhanced formation of catalytically active Pd nanoparticles. Catalysts with the chip-based format allow for simple separation and in-situ monitoring of the reaction extent. Thorough examination of synthesis-structure-activity relationship of Pd nanoparticles formed on surface-assembled viral templates shows that Pd nanoparticle size, catalyst loading density and catalytic activity of viral-templated Pd nanocatalysts can be readily controlled simply by tuning the synthesis conditions. The viral-templated Pd nanocatalysts with optimized synthesis conditions are shown to have higher catalytic activity per unit Pd mass than the commercial Pd/C catalysts. Furthermore, tunable and selective surface assembly of TMV biotemplates is exploited to control the loading density and location of Pd nanocatalysts on solid substrates via preferential electroless deposition. In addition, the catalytic activities of surface-assembled TMV-templated Pd nanocatalysts were also investigated for the ligand-free Suzuki Coupling reaction under mild reaction conditions. The chip-based format enables simple catalyst separation and

  11. Comparing the methods for determination of carbon in soil

    NASA Astrophysics Data System (ADS)

    Bidló, A.; Szżcs, P.; Horváth, A.; Kámán, O.; Németh, E.; Juhász, P.

    2012-04-01

    The global climate change raised the question of carbon sequestration of forests. Forests are important natural carbon sequesters in the temperate zone. It can be ascertained, that a significant part of carbon (often more than half of it), can be found in the soil. The greater amount of carbon can be found in the organic substance of soil (humus). There are several methods for determination of carbon in soil. The most popular method is determination by dry-burning, which means that the samples are exposed to high temperature and the amount of carbon content of CO2 becomes observable with the help of thermal conductivity detector or infrared spectroscopy. The advantage of this system is that burning and carbon content determination happens in a reproducible way if the conditions are satisfactory. However, this method is limited, because e. g. in Hungary the soil contains too much lime (often above 50%) and during the burning CO2 evolves from decomposition of minerals. The previous hydrochloric destruction of carbonate is not usable for lime content during examination. In the case of soils with high lime content the application of wet oxidation by potassium dichromate for organic matter determination is correct. During our investigation we made a comparison between the results of dry and three different wet burning, in the same way we did with organic matter determination in parallel with the determination of 320 soil samples. Between the results of wet burning we detected a decided difference. The Tyurin-type humus (Benediktas 2006, Tóth and Szabó 2003) determination (which is widely applied in Eastern Europe and it is a gas burning destruction method) showed high dispersion. The other destruction method showed favourable results, this method is applied on water bath, and is corresponding to the Hungarian standard. The correlation coefficient was between 0,87 és 0,98 amongst three analytical methods. We made a comparison between results of wet and dry burning

  12. NMR studies on the chemical alteration of soil organic matter precursors during controlled charring

    NASA Astrophysics Data System (ADS)

    Knicker, Heike

    2010-05-01

    Beside the production of volatiles, vegetation fire transforms various amounts of labile organic components into recalcitrant dark colored and highly aromatic structures. They are incorporated into soils and are assumed to represent an important sink within the global carbon cycle. In order to elucidate the real importance of PyOM as a C-sink, a good understanding of its chemistry is crucial. Although several 'Black Carbon' (BC) models are reported, a commonly accepted view of the chemistry involved in its formation is still missing. Its biogeochemical recalcitrance is commonly associated with a highly condensed aromatic structure. However, recent studies indicated that this view may be oversimplified for PyOM derived from vegetation fire. In order to bring some more light on the structural properties of PyOM produced during vegetation fire, charred plant residues and model chars derived from typical plant macromolecules (casein, cellulose, lignin and condensed tannins) were subjected to controlled charring under oxic conditions (350°C and 450°C) and then characterized by nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Subsequently, the chemical features of the PyOM were related to its chemical recalcitrance as determined by chemical oxidation with acid potassium dichromate. Charring cellulose (350°C, 8 min) yielded in a low C-recovery (11%). Treating casein in the same way resulted in a survival of 62% of its C and 46% of its N. Comparable high C-recoveries are reported for lignin. After charring Lolium perenne, 34% of its N and C were recovered. NMR-spectroscopic studies revealed that for this sample most of the charred N and C occurred in pyrrole-type structures. Our studies further indicate that the aromatic skeleton of char accumulating after a vegetation fire must contain remains of the lignin backbone and considerable contributions of furans and anhydrosugars from thermally altered cellulose. Enhancing the temperature during the

  13. Examination of a vehicle for use with water soluble materials in the murine local lymph node assay.

    PubMed

    Ryan, C A; Cruse, L W; Skinner, R A; Dearman, R J; Kimber, I; Gerberick, G F

    2002-11-01

    The murine local lymph node assay (LLNA) is a validated method for identifying skin sensitization hazard. Vehicle choice can influence the sensitization potential of haptens in both the LLNA and in humans, therefore selection of an appropriate vehicle is important. Suggested vehicles for the LLNA include organic solvents and organic-aqueous mixtures. However, due to its high surface tension and poor wetting qualities, water is not recommended and therefore testing aqueous soluble materials can be problematic. The aims of this investigation were to identify a water-based vehicle that possesses better skin wetting properties than water alone, and to assess its performance relative to other solvents in the LLNA using aqueous soluble haptens. The selected wetting agent was the surfactant Pluronic(R) L92 (L92). Concentrations of L92 of up to 50% did not induce positive responses in the LLNA. 1% aqueous L92 was chosen for further examination. Dose-response analyses were performed with dinitrobenzene sulfonic acid (DNBS) and formaldehyde formulated either in water, 1% L92, dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). Potassium dichromate (PDC) and nickel sulfate were tested in 1% L92, DMSO or DMF. The highest concentration of potassium dichromate was retested in each vehicle and in water to assess the effect of the wetting agent. Estimates of the relative sensitizing potency in each vehicle were determined by calculation of EC3 values (the estimated concentration required to induce a threshold positive response). While DNBS and formaldehyde produced positive responses in all four vehicles, their relative potency varied among the vehicles. The rank ordering of potencies for both materials was, from highest to lowest, DMF > or = DMSO > 1% L92 > water. Compared with water, use of 1% L92 resulted in >2-fold increase in potency for DNBS and >3-fold increase for formaldehyde. PDC was positive in DMF, DMSO and 1% L92. The potency ranking was DMF > or = DMSO > 1% L92

  14. RESULTS FROM RECENT SCIENCE AND TECHNOLOGY INVESTIGATIONS TARGETING CHROMIUM IN THE 100D AREA HANFORD SITE WASHINGTON USA

    SciTech Connect

    PETERSEN SW; THOMPSON KM; TONKIN MJ

    2009-12-03

    Sodium dichromate was used in Hanford's 100D Area during the reactor operations period of 1950 to 1964 to retard corrosion in the reactor cooling systems. Some of the sodium dichromate was released to the environment by spills and/or leaks from pipelines used to deliver the chemical to water treatment plants in the area. As a result, hexavalent chromium [Cr(VI)] has migrated through the vadose zone to the groundwater and contaminated nearly 1 km{sup 2} of groundwater to above the drinking water standard of 48 {micro}g/L. Three technology tests have recently been completed in this area to characterize the source area of the plumes and evaluate alternative methods to remove Cr(VI) from groundwater. These are (1) refine the source area of the southern plume; (2) test electrocoagulation as an alternative groundwater treatment technology; and (3) test the ability to repair a permeable reactive barrier by injecting micron or nanometer-size zero-valent iron (ZVI). The projects were funded by the US Department of Energy as part of a program to interject new technologies and accelerate active cleanup. Groundwater monitoring over the past 10 years has shown that Cr(VI) concentrations in the southern plume have not significantly diminished, strongly indicating a continuing source. Eleven groundwater wells were installed in 2007 and 2008 near a suspected source area and monitored for Cr(VI) and groundwater levels. Interpretation of these data has led to refinement of the source area location to an area of less than 1 hectare (ha, 2.5 acres). Vadose zone soil samples collected during drilling did not discover significant concentrations of Cr(VI), indicating the source is localized, with a narrow wetted path from the surface to the water table. Electrocoagulation was evaluated through a pilot-scale treatability test. Over 8 million liters of groundwater were treated to Cr(VI) concentrations of {le}20 {micro}g/L. The test determined that this technology has the potential to treat

  15. Observational Approach to Chromium Site Remediation - 13266

    SciTech Connect

    Scott Myers, R.

    2013-07-01

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the observational

  16. Resveratrol protects the ovary against chromium-toxicity by enhancing endogenous antioxidant enzymes and inhibiting metabolic clearance of estradiol.

    PubMed

    Banu, Sakhila K; Stanley, Jone A; Sivakumar, Kirthiram K; Arosh, Joe A; Burghardt, Robert C

    2016-07-15

    Resveratrol (RVT), a polyphenolic component in grapes and red wine, has been known for its cytoprotective actions against several diseases. However, beneficial effects of RVT against early exposure to endocrine disrupting chemicals (EDCs) have not been understood. EDCs are linked to several ovarian diseases such as premature ovarian failure, polycystic ovary syndrome, early menopause and infertility in women. Hexavalent chromium (CrVI) is a heavy metal EDC, and widely used in >50 industries. Environmental contamination with CrVI in the US is rapidly increasing, predisposing the human to several illnesses including cancers and still birth. Our lab has been involved in determining the molecular mechanism of CrVI-induced female infertility and intervention strategies to mitigate CrVI effects. Lactating mother rats were exposed to CrVI (50ppm potassium dichromate) from postpartum days 1-21 through drinking water with or without RVT (10mg/kg body wt., through oral gavage daily). During this time, F1 females received respective treatments through mother's milk. On postnatal day (PND) 25, blood and the ovary, kidney and liver were collected from the F1 females for analyses. CrVI increased atresia of follicles by increasing cytochrome C and cleaved caspase-3; decreasing antiapoptotic proteins; decreasing estradiol (E2) biosynthesis and enhancing metabolic clearance of E2, increasing oxidative stress and decreasing endogenous antioxidants. RVT mitigated the effects of CrVI by upregulating cell survival proteins and AOXs; and restored E2 levels by inhibiting hydroxylation, glucuronidation and sulphation of E2. This is the first study to report the protective effects of RVT against any toxicant in the ovary. PMID:27129868

  17. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  18. Prenatal exposure to chromium induces early reproductive senescence by increasing germ cell apoptosis and advancing germ cell cyst breakdown in the F1 offspring

    PubMed Central

    Sivakumar, Kirthiram K.; Stanley, Jone A.; Arosh, Joe A.; Pepling, Melissa E.; Burghardt, Robert C.; Banu, Sakhila K.

    2014-01-01

    Hexavalent chromium (CrVI), one of the more toxic heavy metals, is widely used in more than 50 industries such as chrome plating, welding, wood processing and tanneries. As one of the world’s leading producers of chromium compounds, the U.S. is facing growing challenges in protecting human health against multiple adverse effects of CrVI. CrVI is rapidly converted to CrIII intracellularly, and can induce apoptosis through different mechanisms. Our previous studies demonstrated postnatal exposure to CrVI results in a delay or arrest in follicle development and puberty. Pregnant rats were treated with 25 ppm potassium dichromate (CrVI) from gestational day (GD) 9.5 to 14.5 through drinking water, placentae were removed on GD 20, and total Cr was estimated in the placentae; ovaries were removed from the F1 offspring on postnatal day (PND)-1 and various analyses were performed. Our results show that gestational exposure to CrVI resulted in (i) increased Cr concentration in the placenta, (ii) increased germ cell apoptosis by up-regulating p53/p27–Bax–caspase-3 proteins and by increasing p53–SOD-2 co-localization; (iii) accelerated germ cell cyst (GCC) breakdown; (iv) advanced primordial follicle assembly and primary follicle transition and (v) down regulation of p-AKT, p-ERK and XIAP. As a result of the above events, CrVI induced early reproductive senescence and decrease in litter size in F1 female progeny. PMID:24530425

  19. New light-trapping concept by means of several optical components applied to compact holographic 3D concentration solar module

    NASA Astrophysics Data System (ADS)

    Villamarín Villegas, Ayalid M.; Pérez López, Francisco J.; Calo López, Antonio; Rodríguez San Segundo, Hugo-José

    2014-05-01

    A new light-trapping concept is presented, which joins broad bandwidth volume phase reflection holograms (VPRH) working together with three other optical components: specifically designed three-dimensional (3D) cavities, Total Internal Reflection (TIR) within an optical medium, and specular reflection by means of a highly reflective surface. This concept is applied to the design and development of both low concentration photovoltaic (LCPV) and solar thermal modules reaching a concentration factor of up to 3X. Higher concentrations are feasible for use in concentrated solar power (CSP) devices. The whole system is entirely made of polymeric materials (except for the solar cells or fluid carrying pipes), thus reducing cost by up to 40%. The module concentrates solar light onto solar cells - or fluid carrying pipes - with no need for active tracking of the sun, covering the whole seasonal and daily incident angle spectrum while it also minimizes optical losses. In this work we analyze the first experimentally measured optical characteristics and performance of VPRH in dichromated gelatin film (DCG) in our concept. The VPRH can reach high diffraction efficiencies (˜98%, ignoring Fresnel reflection losses). Thanks to specifically designed raw material, coating and developing process specifications, also very broad selective spectral (higher than 300 nm) and angular bandwidths (˜+20º) per grating are achieved. The VPRH was optimized to use silicon solar cells, but designs for other semiconductor devices or for fluid heating are feasible. The 3D shape, the hologram's and reflective surface's optical quality, the TIR effect and the correct coupling of all the components are key to high performance of the concentration solar module.

  20. Evaluation of Acinetobacter sp. B9 for Cr (VI) resistance and detoxification with potential application in bioremediation of heavy-metals-rich industrial wastewater.

    PubMed

    Bhattacharya, Amrik; Gupta, Anshu

    2013-09-01

    Present work demonstrates Cr (VI) detoxification and resistance mechanism of a newly isolated strain (B9) of Acinetobacter sp. Bioremediation potential of the strain B9 is shown by simultaneous removal of major heavy metals including chromium from heavy-metals-rich metal finishing industrial wastewater. Strain B9 tolerate up to 350 mg L(-1) of Cr (VI) and also shows level of tolerance to Ni (II), Zn (II), Pb (II), and Cd (II). The strain was capable of reducing 67 % of initial 7.0 mg L(-1) of Cr (VI) within 24 h of incubation, while in presence of Cu ions 100 % removal of initial 7.0 and 10 mg L(-1) of Cr (VI) was observed with in 24 h. pH in the range of 6.0-8.0 and inoculum size of 2 % (v/v) were determined to be optimum for dichromate reduction. Fourier transform infrared spectroscopy and transmission electron microscopy studies suggested absorption or intracellular accumulation and that might be one of the major mechanisms behind the chromium resistance by strain B9. Scanning electron microscopy showed morphological changes in the strain due to chromium stress. Relevance of the strain for treatment of heavy-metals-rich industrial wastewater resulted in 93.7, 55.4, and 68.94 % removal of initial 30 mg L(-1) Cr (VI), 246 mg L(-1) total Cr, and 51 mg L(-1) Ni, respectively, after 144 h of treatment in a batch mode. PMID:23619927

  1. Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

    NASA Astrophysics Data System (ADS)

    Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

    2006-05-01

    A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (<1 μm) cubic highly crystalline precipitates on the flyash, although this new crystalline zeolite growth did not occur rapidly enough to enable productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

  2. Application of the Stopped Flow Technique to the TiO₂-Heterogeneous Photocatalysis of Hexavalent Chromium in Aqueous Suspensions: Comparison with O₂ and H₂O₂ as Electron Acceptors.

    PubMed

    Meichtry, Jorge M; Dillert, Ralf; Bahnemann, Detlef W; Litter, Marta I

    2015-06-01

    The dynamics of the transfer of electrons stored in TiO2 nanoparticles to Cr(VI) in aqueous solution have been investigated using the stopped flow technique. TiO2 nanoparticles were previously irradiated under UV light in the presence of formic acid, and trapped electrons (e(trap)(-)) were made to react with Cr(VI) as acceptor species; other common acceptor species such as O2 and H2O2 were also tested. The temporal evolution of the number of trapped electrons was followed by the decrease in the absorbance at 600 nm, and the kinetics of the electron-transfer reaction was modeled. Additionally, the rate of formation of the surface complex between Cr(VI) and TiO2 was determined with the stopped flow technique by following the evolution of the absorbance at 400 nm of suspensions of nonirradiated TiO2 nanoparticles and Cr(VI) at different concentrations. An approximately quadratic relationship was observed between the maximum absorbance of the surface complex and the concentration of Cr(VI), suggesting that Cr(VI) adsorbs onto the TiO2 surface as dichromate. The kinetic analyses indicate that the electron transfer from TiO2 to Cr(VI) does not require the previous formation of the Cr(VI)-TiO2 surface complex, at least the complex detected here through the stopped flow experiments. When previously irradiated TiO2 was used to follow the evolution of the Cr(VI)-TiO2 complex, an inhibition of the formation of the complex was observed, which can be related to the TiO2 deactivation caused by Cr(III) deposition. PMID:25974749

  3. Facile Synthesis of n-type (AgIn)(x)Zn(2(1-x))S2/p-type Ag2S Nanocomposite for Visible Light Photocatalytic Reduction To Detoxify Hexavalent Chromium.

    PubMed

    Abdullah, Hairus; Kuo, Dong-Hau

    2015-12-01

    n-type (AgIn)(x)Zn(2(1-x))S2/p-type Ag2S nanocomposites with 10%, 20%, and 30% Ag2S loading were successfully synthesized via the simple solvothermal and sol gel methods. The as-prepared nanocomposites were characterized, and their visible light photocatalytic reductions were tested for detoxification of hexavalent chromium (Cr(VI)). The results showed only 20 mg of the as-prepared nanocomposites could reduce 100 mL of 20 ppm potassium dichromate by almost 100% in less than 90 min without adding any hole scavenger agents and pH adjustment (pH = 7). The good photocatalytic reduction was related to the narrower bandgap of (AgIn)(x)Zn(2(1-x))S2 solid solution because of the hybridized orbitals of Ag, In, Zn, and S and low recombination rate of photogenerated electron and hole pairs due to the effectiveness of p-type Ag2S and n-type (AgIn)(x)Zn(2(1-x))S2 nanoheterojunctions. This work not only gives a contribution to the creation of visible light photocatalysis for wide-bandgap semiconductors, but also extends our technological viewpoints in designing highly efficient metal sulfide photocatalyst. To the best of our knowledge, this work is the first finding of a high photocatalytic reduction of hexavalent chromium under visible light illumination by simultaneously using both concepts of p-n nanoheterojunction and solid solution in our photocatalyst design. In this present work, these concepts were used to replace the use of hole scavenger agents, which were commonly used by many other works to retard the recombination rate of photoinduced electron and hole pairs for photodegradation of hexavalent chromium. PMID:26575792

  4. Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study.

    PubMed

    Riew, Tae-Ryong; Shin, Yoo-Jin; Kim, Hong Lim; Cho, Jeong Min; Pak, Ha-Jin; Lee, Mun-Yong

    2016-01-01

    Calcification in areas of neuronal degeneration is a common finding in several neuropathological disorders including ischemic insults. Here, we performed a detailed examination of the onset and spatiotemporal profile of calcification in the CA1 region of the hippocampus, where neuronal death has been observed after transient forebrain ischemia. Histopathological examinations showed very little alizarin red staining in the CA1 pyramidal cell layer until day 28 after reperfusion, while prominent alizarin red staining was detected in CA1 dendritic subfields, particularly in the stratum radiatum, by 14 days after reperfusion. Electron microscopy using the osmium/potassium dichromate method and electron probe microanalysis revealed selective calcium deposits within the mitochondria of degenerating dendrites at as early as 7 days after reperfusion, with subsequent complete mineralization occurring throughout the dendrites, which then coalesced to form larger mineral conglomerates with the adjacent calcifying neurites by 14 days after reperfusion. Large calcifying deposits were frequently observed at 28 days after reperfusion, when they were closely associated with or completely engulfed by astrocytes. In contrast, no prominent calcification was observed in the somata of CA1 pyramidal neurons showing the characteristic features of necrotic cell death after ischemia, although what appeared to be calcified mitochondria were noted in some degenerated neurons that became dark and condensed. Thus, our data indicate that intrahippocampal calcification after ischemic insults initially occurs within the mitochondria of degenerating dendrites, which leads to the extensive calcification that is associated with ischemic injuries. These findings suggest that in degenerating neurons, the calcified mitochondria in the dendrites, rather than in the somata, may serve as the nidus for further calcium precipitation in the ischemic hippocampus. PMID:27414398

  5. Section 9.1 new dosimeters. New dosimetry systems

    NASA Astrophysics Data System (ADS)

    McLaughlin, William L.

    During the past two years there have been significant advances in several forms of radiation measurement systems for radiation processing, covering dose ranges of 1-10 6 Gy. Calorimeters as reference standards for both ionizing photon and electron fields have become well-established. In addition to the older ceric-cerous dosimetry solution analyzed potentiometrically, new liquid-phase dosimeters include those analyzed by spectrophotometry, e.g., improved forms of acidic aqueous solutions of K-Ag dichromate and organic radiochromic dye solutions. It has recently been demonstrated that by using certain refined sugars, e.g., D-(-) ribose, optical rotation response in aqueous solutions can be enhanced for dosimetry at doses > 10 4 Gy. There has been expanded development, use, and formulation (rods, tablets, and thin films) of the amino acid, alanine, as a solid-phase dosimeter analyzed by either ESR spectrometry or by glutamine or alanine spectrophotometry of complexes with ferric ion in the presence of a sulfonphthalein dye (xylenol orange). New commercial types of radiochromic plastic dosimeters, e.g., GafChromic TM, Riso B3 TM, GAMMACHROME YR TM, Radix TM, and Gammex TM, have been introduced and applied in practice. Improvements and broader use of optical waveguide dosimeters, e.g., Opti-Chromic TM, have also been reported, especially in food irradiation applications. Several novel dyed plastic dosimeters are available in large quantities and they lose color due to irradiation. An example is a dyed cellulosic thin film (ATC type DY-42 TM) which can be measured spectrophotometrically or densitometrically up to doses as high as 10 6 Gy.

  6. Adsorption of divalent metal ions from aqueous solutions using graphene oxide.

    PubMed

    Sitko, Rafal; Turek, Edyta; Zawisza, Beata; Malicka, Ewa; Talik, Ewa; Heimann, Jan; Gagor, Anna; Feist, Barbara; Wrzalik, Roman

    2013-04-28

    The adsorptive properties of graphene oxide (GO) towards divalent metal ions (copper, zinc, cadmium and lead) were investigated. GO prepared through the oxidation of graphite using potassium dichromate was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR). The results of batch experiments and measurements by flame atomic absorption spectrometry (F-AAS) indicate that maximum adsorption can be achieved in broad pH ranges: 3-7 for Cu(II), 5-8 for Zn(II), 4-8 for Cd(II), 3-7 for Pb(II). The maximum adsorption capacities of Cu(II), Zn(II), Cd(II) and Pb(II) on GO at pH = 5 are 294, 345, 530, 1119 mg g(-1), respectively. The competitive adsorption experiments showed the affinity in the order of Pb(II) > Cu(II) ≫ Cd(II) > Zn(II). Adsorption isotherms and kinetic studies suggest that sorption of metal ions on GO nanosheets is monolayer coverage and adsorption is controlled by chemical adsorption involving the strong surface complexation of metal ions with the oxygen-containing groups on the surface of GO. Chemisorption was confirmed by XPS (binding energy and shape of O1s and C1s peaks) of GO with adsorbed metal ions. The adsorption experiments show that the dispersibility of GO in water changes remarkably after complexation of metal ions. After adsorption, the tendency to agglomerate and precipitate is observed. Excellent dispersibility of GO and strong tendency of GO-Me(II) to precipitate open the path to removal of heavy metals from water solution. Potential application of GO in analytical chemistry as a solid sorbent for preconcentration of trace elements and in heavy metal ion pollution cleanup results from its maximum adsorption capacities that are much higher than those of any of the currently reported sorbents. PMID:23443993

  7. Adsorption studies of chromium (VI) removal from water by lanthanum diethanolamine hybrid material.

    PubMed

    Mandal, Sandip; Sahu, Manoj Kumar; Giri, Anil Kumar; Patel, Raj Kishore

    2014-01-01

    In the present research work, lanthanum diethanolamine hybrid material is synthesized by co-precipitation method and used for the removal of Cr(VI) from synthetic dichromate solution and hand pump water sample. The sorption experiments were carried out in batch mode to optimize various influencing parameters such as adsorbent dose, contact time, pH, competitive anions and temperature. The characterization of the material and mechanism of Cr(VI) adsorption on the material was studied by using scanning electron microscope, Fourier transform infrared, X-ray diffraction, Brunauer-Emmett-Teller and thermogravimetric analysis-differential thermal analysis. Adsorption kinetics studies reveal that the adsorption process followed first-order kinetics and intraparticle diffusion model with correlation coefficients (R2) of 0.96 and 0.97, respectively. The adsorption data were best fitted to linearly transformed Langmuir isotherm with correlation coefficient (R2) of 0.997. The maximum removal of Cr(VI) is found to be 99.31% at optimal condition: pH = 5.6 of the solution, adsorbent dose of 8 g L(-1) with initial concentration of 10mgL(-1) of Cr(VI) solution and an equilibrium time of 50 min. The maximum adsorption capacity of the material is 357.1 mg g(-1). Thermodynamic parameters were evaluated to study the effect of temperature on the removal process. The study shows that the adsorption process is feasible and endothermic in nature. The value of E (260.6 kJ mol(-1)) indicates the chemisorption nature of the adsorption process. The material is difficult to be regenerated. The above studies indicate that the hybrid material is capable of removing Cr(VI) from water. PMID:24645464

  8. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana.

    PubMed

    Eleftheriou, Eleftherios P; Adamakis, Ioannis-Dimosthenis S; Panteris, Emmanuel; Fatsiou, Maria

    2015-01-01

    Chromium (Cr) is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI)], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7), in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2) production and peroxidase activity were found in Cr(VI)-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER) was less affected under Cr(VI) stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS)-correlated and the malformations observed are organelle specific. PMID:26204828

  9. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana.

    PubMed

    Eleftheriou, Eleftherios P; Adamakis, Ioannis-Dimosthenis S; Panteris, Emmanuel; Fatsiou, Maria

    2015-01-01

    Chromium (Cr) is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI)], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7), in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2) production and peroxidase activity were found in Cr(VI)-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER) was less affected under Cr(VI) stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS)-correlated and the malformations observed are organelle specific. PMID:26184178

  10. Hexavalent chromium-induced apoptosis of granulosa cells involves selective sub-cellular translocation of Bcl-2 members, ERK1/2 and p53

    SciTech Connect

    Banu, Sakhila K.; Stanley, Jone A.; Lee, JeHoon; Stephen, Sam D.; Arosh, Joe A.; Hoyer, Patricia B.; Burghardt, Robert C.

    2011-03-15

    Hexavalent chromium (CrVI) has been widely used in industries throughout the world. Increased usage of CrVI and atmospheric emission of CrVI from catalytic converters of automobiles, and its improper disposal causes various health hazards including female infertility. Recently we have reported that lactational exposure to CrVI induced a delay/arrest in follicular development at the secondary follicular stage. In order to investigate the underlying mechanism, primary cultures of rat granulosa cells were treated with 10 {mu}M potassium dichromate (CrVI) for 12 and 24 h, with or without vitamin C pre-treatment for 24 h. The effects of CrVI on intrinsic apoptotic pathway(s) were investigated. Our data indicated that CrVI: (i) induced DNA fragmentation and increased apoptosis, (ii) increased cytochrome c release from the mitochondria to cytosol, (iii) downregulated anti-apoptotic Bcl-2, Bcl-XL, HSP70 and HSP90; upregulated pro-apoptotic BAX and BAD, (iv) altered translocation of Bcl-2, Bcl-XL, BAX, BAD, HSP70 and HSP90 to the mitochondria, (v) upregulated p-ERK and p-JNK, and selectively translocated p-ERK to the mitochondria and nucleus, (vi) activated caspase-3 and PARP, and (vii) increased phosphorylation of p53 at ser-6, ser-9, ser-15, ser-20, ser-37, ser-46 and ser-392, increased p53 transcriptional activation, and downregulated MDM-2. Vitamin C pre-treatment mitigated CrVI effects on apoptosis and related pathways. Our study, for the first time provides a clear insight into the effect of CrVI on multiple pathways that lead to apoptosis of granulosa cells which could be mitigated by vitamin C.

  11. Bovine Cryptosporidiosis: Clinical and Pathological Findings in Forty-two Scouring Neonatal Calves

    PubMed Central

    Sanford, S. E.; Josephson, G. K. A.

    1982-01-01

    Cryptosporidia organisms were identified in 42 of 161 (26%) neonatal, diarrheic calves, over a 32 month period commencing July 1979. Forty of the 161 calves were submitted alive and cryptosporidiosis was diagnosed in 63% (25 of 40) of them. The cryptosporidia infected calves were usually one to two weeks old and came from 26 herds where the typical history was profuse, watery diarrhea in nearly all neonatal calves. The diarrhea usually started around one week of age, was unresponsive to all conventional antidiarrhea therapies, lasted for two or more weeks and was usually fatal. Twenty-nine (69%) of the cryptosporidia infected calves were submitted between December and February. These calves were often hutch reared. Histopatholoical examination revealed large numbers of the coccidial parasite Cryptosporidium sp embedded in the microvilli of jejunal and ileal absorptive enterocytes of all affected calves. The organisms were identified as trophozoites and schizonts (asexual stages) and macrogametes (female sexual stages) with the electron microscope. Microgametes (male sexual stages) were not identified. Occasionally a merozoite (asexual stage) was also seen apparently burrowing into or about to be enveloped by a host microvillus. Observation of the organisms was much easier when diarrheic calves were submitted alive. Enterotoxigenic Escherichia coli were often cultured from intestines of dead calves and occasionally from calves submitted alive. Coronavirus particles were seen in one calf. In the last year of this study, oocysts were identified in fecal smears stained with May-Grünwald-Giemsa stain and fecal samples using a dichromate solution flotation technique. ImagesFigure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7. PMID:17422204

  12. Natural Attenuation of Anthropogenic Chromium in Selected Puye Formation in Regional Aquifer System of LOS Alamos, New Mexico

    NASA Astrophysics Data System (ADS)

    Brown, D. B.; Ding, M.; WoldeGabriel, G. W.; Cheshire, M.; Rearick, M.; Conradson, S.; Kluk, E.; Katzman, D.

    2014-12-01

    Routine groundwater monitoring conducted in 2005 revealed significant chromium (Cr) contamination in regional groundwater in Los Alamos, New Mexico. Previous use of potassium dichromate (K2Cr2O7) in cooling towers at Los Alamos National Laboratory's main power plant is believed to be the source of the elevated chromium levels. From 1956 to 1972 between 31,000 and 72,000 Kg of toxic Cr(IV) was released into Sandia Canyon. Initial investigations of the vadose zone using chromium isotopes indicated that reduction of anthropogenic Cr(IV) had occurred. However, to justify the use of Monitoring Natural Attenuation (MNA) as a valid remediation strategy, the Cr attenuation mechanism and the reduction capacity of the regional aquifer needs to be determined. Conventional batch sorption and synchrotron-based X-ray absorption spectroscopy studies were performed. Two samples were selected from the Puye formation, a silicoclastic sedimentary rock sequence located within the contaminated aquifer. Additionally, two Los Alamos Puye outcrop samples with no chromium exposure were selected for comparison. Each sample was subsequently sorted based on grain size, magnetic, and clay fractions. Groundwater with a known concentration of Cr(IV) was used in the batch experiments. Spectroscopy measurements of Puye samples before and after exposure to the same contaminated groundwater were conducted at the Stanford Synchrotron Radiation Lightsource (SSRL). Batch sorption results indicated little to no attenuation, as indicated by the small measured sorption coefficient (Kd < 5 Kg/L). Spectroscopic measurements suggest that attenuation of hexavalent chromium in groundwater is due to reduction of Cr(VI) to Cr(III) in the Puye and may be attributed almost exclusively to the clay fraction. These results indicate that the tested Puye sediments occurring in the regional aquifer have minor ability to naturally attenuate anthropogenic Cr(IV), with the clay fraction dominating the reduction process

  13. Chromium speciation in oxide-type compounds: application to minerals, gems, aqueous solutions and silicate glasses

    NASA Astrophysics Data System (ADS)

    Farges, François

    2009-09-01

    Cr K-edge XANES spectra were obtained for a variety of Cr-bearing model compounds containing Cr(II), Cr(III), Cr(IV), Cr(V) and Cr(VI), in which the Cr-site symmetry is D4h, Oh and Td. The centroid position of the pre-edge feature is a better indicator of the Cr valence than the edge position. In Cr-rich oxides, higher-energy transitions must be excluded in order to refine a robust valence for Cr. The pre-edge for chromates is not unique and varies as a function of the CrO4 2- moiety distortion, which is often related to Cr-polymerization (monochromate vs. dichromate). Both the analogy with the Mn K-pre-edge information and ab initio FEFF calculations of the pre-edge feature for Cr(III) and Cr(VI) confirm the experimental trends. This methodology is applied to the Cr K-edge pre-edge feature collected in gems (emerald, spinel and ruby), the layered minerals fuchsite and kämmererite, two Cr-bearing aqueous solutions and a set of sodo-calcic silicate glasses used for bottling sparkling white wine. In emerald and fuchsite, the Cr-site is differently distorted than its ruby or spinel counterpart. In a Cr(III)-bearing aqueous solution and sodo-calcic glass, no evidence for Cr(III) with Td and C3v symmetry is detected. However, minor amounts of chromate moieties (most likely monomeric) are detected in a glass synthesized in air. Preliminary spectra for the wine bottle glass suggest that only trace amounts of chromates might possibly be present in these glasses.

  14. Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater

    PubMed Central

    Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N.

    2012-01-01

    A novel reactive electrochemical flow system consisting of iron anode and porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides proton and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (< 7.5 mg/L) and high current (> 45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants from flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures. PMID:23067023

  15. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana

    PubMed Central

    Eleftheriou, Eleftherios P.; Adamakis, Ioannis-Dimosthenis S.; Panteris, Emmanuel; Fatsiou, Maria

    2015-01-01

    Chromium (Cr) is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI)], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7), in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2) production and peroxidase activity were found in Cr(VI)-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER) was less affected under Cr(VI) stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS)-correlated and the malformations observed are organelle specific.

  16. High-efficiency cadmium and zinc-telluride-based thin-film solar cells. Annual subcontract report, 1 March 1990--28 February 1991

    SciTech Connect

    Rohatgi, A.; Sudharsanan, R.; Ringel, S.

    1992-02-01

    This report describes research into polycrystalline CdTe solar cells grown by metal-organic chemical vapor deposition. Efficiencies of {approximately}10% were achieved using both p-i-n and p-n structures. A pre-heat treatment of CdS/SnO{sub 2}/glass substrates at 450{degrees}C in hydrogen atmosphere prior to the CdTe growth was found to be essential for high performance because this heat treatment reduces oxygen-related defects from the CdS surface. However, this treatment also resulted in a Cd-deficient CdS surface, which may in part limit the CdTe cell efficiency to 10% due to Cd vacancy-related interface defects. Preliminary model calculations suggest that removing these states can increase the cell efficiency from 10% to 13.5%. Photon absorption in the CdS film also limits the cell performance, and eliminating this loss mechanism can result in CdTe efficiencies in excess of 18%. Polycrystalline, 1.7-e, CdZnTe films were also grown for tandem-cell applications. CdZnTe/CdS cells processed using the standard CdTe cell fabrication procedure resulted in 4.4% efficiency, high series resistance, and a band-gap shift to 1.55 eV. The formation of Zn-O at and near the CdZnTe surface is the source of high contact resistance. A saturated dichromate each prior to contact deposition was found to solve the contact resistance problem. The CdCl{sub 2} treatment was identified as the cause of the observed band-gap shift due to the preferred formation of ZnCl{sub 2}. 59 refs.

  17. The effectiveness of ferrous iron and sodium dithionite for decreasing resin-extractable Cr(VI) in Cr(VI)-spiked alkaline soils.

    PubMed

    Cheng, Chia-Jung; Lin, Tzu-Huei; Chen, Chiou-Pin; Juang, Kai-Wei; Lee, Dar-Yuan

    2009-05-30

    Ferrous iron, Na(2)S(2)O(4), and a mixture of Fe(II) and Na(2)S(2)O(4) (4:1 mol/mol) were tested for their effectiveness for decreasing resin-extractable Cr(VI) in alkaline Cr(VI)-spiked soils. The results indicated that adding those reductants greatly decreased the amount of resin-extractable Cr(VI) when the application rate of reductants equaled the number of equivalents of dichromate added to the Cr(VI)-spiked soils. This was mainly as a result of the Cr(VI) reduction into Cr(III), as supported by the XANES spectra. Among the tested reductants, a mixture of Fe(II) and Na(2)S(2)O(4) was the most effective to decrease resin-extractable Cr(VI). The extent to which resin-extractable Cr(VI) and soil pH were decreased was affected by the pH of the reductants. Among the tested reductants at various pH, FeSO(4) at pH below 1 was the most effective in decreasing resin-extractable Cr(VI) in alkaline soils. However, the soil pH was the most decreased as well. On the other hand, the mixtures of ferrous iron and dithionite at a wide range of pH were all efficient (>70% efficiency) in decreasing resin-extractable Cr(VI). Moreover, the extent of the decrease in soil pH was much smaller than that by FeSO(4) (pH<1) alone, and thus the possibility of the Cr(III) hazard can be avoided. PMID:18824300

  18. Effects of drilling fluids on soils and plants: I. Individual fluid components

    SciTech Connect

    Miller, R.W.; Honarvar, S.; Hunsaker, B.

    1980-01-01

    The effects of 31 drilling fluid (drilling mud) components on the growth of green beans (Phaseolus vulgaris L., Tendergreen) and sweet corn (Zea may var. saccharata (Sturtev.) Bailey, Northrup King 199) were evaluated in greenhouse studies. Plants grew well in fertile Dagor silt loam soil (Cumulic Haploxeroll) when the soil was mixed with most soil-component mixtures at disposal proportions normally expected. Vinyl acetate and maleic acid polymer (VAMA) addition caused significantly increased growth at the 95% confidence level. No statistically significant depression of plant growth occurred at normal rates with asbestos, asphalt, barite, bentonite, calcium lignosulfonate, sodium polyacrylate, a modified tannin, ethoxylated nonylphenol, a filming amine, gilsonite, a Xanthan gum, paraformaldehyde, a pipe dope, hydrolized polyacrylamide, sodium acid pyrophosphate, sodium carboxymethyl cellulose, sodium hydroxide added as pellets, and a sulfonated tall oil. Statistically significant reductions in plant yields (at the 95% confidence level) occurred at normal disposal rates with a long-chained aliphatic alcohol, sodium dichromate, diesel oil, guar gum, an iron chromelignosulfonate, lignite, a modified asphalt, a plant fibersynthetic fiber mixture, lignite, a nonfermenting starch, potassium chloride, pregelatinized starch, and sulfated triglyceride. Thirteen drilling fluid components added individually to a fluid base (water, bentonite, and barite) and then to soil were also tested for their effect on plant growth. Only the sulfated triglyceride (Torq-Trim) and the long-chain (high molecular weight) alcohol (Drillaid 405) caused no plant growth reductions at either rate added. The modified tannin (Desco) caused minimal reduction in bean growth only when added to soil in excess levels.

  19. Incidence of allergic contact sensitization in central Chinese subjects with chronic urticaria*

    PubMed Central

    Chen, Hao; Liu, Guanghui; Huang, Nan; Li, Wenjing; Dong, Xiang; Zhu, Rongfei

    2016-01-01

    BACKGROUND Chronic urticaria (CU) can be provoked by a wide variety of causes. Some studies suggest contact sensitization may play a role in the disease. OBJECTIVE To investigate the incidence and distribution characteristics of allergic contact sensitization in central Chinese subjects with CU, and assess contact allergen avoidance measures in managing CU. METHODS Patch tests were performed, following the recommended standard procedure, with 20 selected allergens, in line with the European baseline series. All subjects with positive results were prescribed appropriate avoidance measures for the sensitizing substances, while subjects with negative results served as the control group. CU severity was assessed daily from week1 to week4 and for each subject, applying the Urticaria Activity Score. RESULTS 42.9% (233/543) of subjects with CU showed positive reactions to one or more contact allergen(s). Potassium dichromate, benzene mix and carba mix were more common in male patients, while nickel sulfate was more frequent in females. The positive rates for different allergens varied with age and occupation. The median (interquartile range) severity scores at week 1 were 20 (14-21) and 15 (14-27) for the allergen avoidance group and control group, respectively (P>0.05); and 12 (7-15) and 14 (12-17) at week 4 (P<0.001). CONCLUSION The incidence of allergic contact sensitization in CU patients was high, and appropriate contact allergen avoidance measures benefitted CU management. Contact allergens may play a role in the pathogenic mechanism of CU and patch tests are an option for CU patients. PMID:27192515

  20. Plant Line Trial Evaluation of Viable Non-Chromium Passivation Systems for Electrolytin Tinplate, ETP (TRP 9911)

    SciTech Connect

    John A. Sinsel

    2003-06-30

    Plant trial evaluations have been completed for two zirconium-based, non-chromium passivation systems previously identified as possible alternatives to cathodic dichromate (CDC) passivation for electrolytic tinplate (ETP). These trials were done on a commercial electrolytic tin plating line at Weirton Steel and extensive evaluations of the materials resulting from these trials have been completed. All this was accomplished as a collaborative effort under the AISI Technology Roadmap Program and was executed by seven North American Tin Mill Products producers [Bethlehem Steel (now acquired by International Steel Group (ISG)), Dofasco Inc., National Steel (now acquired by U.S. Steel), U.S. Steel, USS-Posco, Weirton Steel, and Wheeling-Pittsburgh Steel] with funding partially from the Department of Energy (DOE) and partially on an equal cost sharing basis among project participants. The initial phases of this project involved optimization of application procedures for the non-chromium systems in the laboratories at Bethlehem Steel and Betz Dearborn followed by extensive testing with various lacquer formulations and food simulants in the laboratories at Valspar and PPG. Work was also completed at Dofasco and Weirton Steel to develop methods to prevent precipitation of insoluble solids as a function of time from the zirconate system. The results of this testing indicated that sulfide staining characteristics for the non-chromium passivation systems could be minimized but not totally eliminated and neither system was found to perform quite as good, in this respect, as the standard CDC system. As for the stability of zirconate treatment, a method was developed to stabilize this system for a sufficient period of time to conduct plant trial evaluations but, working with a major supplier of zirconium orthosulfate, a method for long term stabilization is still under development.

  1. GROUDWATER REMEDIATION AT THE 100-HR-3 OPERABLE UNIT HANFORD SITE WASHINGTON USA - 11507

    SciTech Connect

    SMOOT JL; BIEBESHEIMER FH; ELUSKIE JA; SPILIOTOPOULOS A; TONKIN MJ; SIMPKIN T

    2011-01-12

    The 100-HR-3 Groundwater Operable Unit (OU) at the Hanford Site underlies three former plutonium production reactors and the associated infrastructure at the 100-D and 100-H Areas. The primary contaminant of concern at the site is hexavalent chromium; the secondary contaminants are strontium-90, technetium-99, tritium, uranium, and nitrate. The hexavalent chromium plume is the largest plume of its type in the state of Washington, covering an area of approximately 7 km{sup 2} (2.7 mi{sup 2}) with concentrations greater than 20 {micro}g/L. Concentrations range from 60,000 {micro}g/L near the former dichromate transfer station in the 100-D Area to large areas of 20 to 100 {micro}g/L across much of the plume area. Pump-and-treat operations began in 1997 and continued into 2010 at a limited scale of approximately 200 gal/min. Remediation of groundwater has been fairly successful in reaching remedial action objectives (RAOs) of 20 {micro}g/L over a limited region at the 100-H, but less effective at 100-D. In 2000, an in situ, permeable reactive barrier was installed downgradient of the hotspot in 100-D as a second remedy. The RAOs are still being exceeded over a large portion of the area. The CH2M HILL Plateau Remediation Company was awarded the remediation contract for groundwater in 2008 and initiated a remedial process optimization study consisting of modeling and technical studies intended to enhance the remediation. As a result of the study, 1,400 gal/min of expanded treatment capacity are being implemented. These new systems are designed to meet 2012 and 2020 target milestones for protection of the Columbia River and cleanup of the groundwater plumes.

  2. Origin and endpoint of the olfactory nerve fibers: as described by Santiago Ramón y Cajal.

    PubMed

    Levine, Catherine; Marcillo, Alexander

    2008-07-01

    In the late Nineteenth Century, Santiago Ramón y Cajal was able to reproduce an exceptional illustration of the Olfactory Nerve pathway and its myriad of cells, by using the Golgi Method. Dr. Cajal focused intense study on the histology of the nervous system and published a treatise on the olfactory nerve fibers and the distinct peripheral origin and central nervous system endpoint of this unique pathway. The original title of this work is "Origen y terminación de las fibras nerviosas olfatorias" published in 1890. As the original publication is in Spanish, here we provide an English translation allowing present-day English speakers to read these writings. Cajal followed the trajectory of the olfactory nerve fibers as they transitioned between the peripheral and central nervous system and was able to assert that these fibers were not continuous from the olfactory bulb to the bipolar cells that relinquish into the olfactory epithelium, but that the olfactory system was made up of various cell types each having distinct morphologies and functions. This may very well be the first definitive description of the olfactory receptor neurons and the first illustrations of the continuity of these cells throughout the olfactory pathway. These meticulous histological preparations were created by first using Camillo Golgi's potassium dichromate and silver nitrate impregnation method known as "reazione nera" or "black reaction," where nerve cells, nerve fibers, and neuroglia could be visualized. This study exhibits the structural and functional organization of the mammalian fila olfactoria as it was investigated in centuries past. PMID:18383279

  3. The toxicity of carbofuran to the freshwater rotifer, Philodina roseola.

    PubMed

    Moreira, Raquel Aparecida; da Silva Mansano, Adrislaine; Rocha, Odete

    2015-04-01

    In this study, the effects of exposing the rotifer Philodina roseola to the pesticide carbofuran were investigated. Its range of sensitivity to potassium dichromate, the acute toxicity of active ingredient carbofuran and of carbofuran dosed as its commercial form, Furadan(®) 350 SC were determined. Chronic toxicity of carbofuran dosed as Furadan(®) 350 SC on P. roseola survival and fecundity were also studied. The sensitivity of P. roseola to K2Cr2O7 ranged from 29.52 to 64.67 mg L(-1), averaging 47.10 mg L(-1). The 48-h EC50 were 13.36 ± 2.63 mg L(-1) for carbofuran and 89.32 ± 6.52 mg L(-1) for commercial form. Chronic toxicity tests showed that the survival of this rotifer was not affected by the carbofuran dosed as Furadan(®) 350 SC at the concentrations tested and that at 1.56 and 3.12 mg L(-1) their fecundity was higher than in the absence of this commercial product, characterizing the hormesis phenomenon. The sensitivity profile of several species to carbofuran indicated that P. roseola is more susceptible to this pesticide than the fish Clarias batrachus, the bacterium Vibrio fischeri, the protozoan Paramecium caudatum and the rotifer Brachionus calyciflorus, although the acute toxicity of carbofuran dosed as Furadan(®) 350 SC to P. roseola is much lower than that of active ingredient carbofuran. The results also imply that the exacerbated use of pesticides and the constant, accelerated expansion of agricultural activity will make aquatic non-target species even more vulnerable. Furthermore, the relevant role of benthic organisms in aquatic environments justifies the inclusion of P. roseola and other benthic species in toxicity screening for risk assessment, regarding this environmental compartment. PMID:25588673

  4. Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study

    PubMed Central

    Kim, Hong Lim; Cho, Jeong Min; Pak, Ha-Jin; Lee, Mun-Yong

    2016-01-01

    Calcification in areas of neuronal degeneration is a common finding in several neuropathological disorders including ischemic insults. Here, we performed a detailed examination of the onset and spatiotemporal profile of calcification in the CA1 region of the hippocampus, where neuronal death has been observed after transient forebrain ischemia. Histopathological examinations showed very little alizarin red staining in the CA1 pyramidal cell layer until day 28 after reperfusion, while prominent alizarin red staining was detected in CA1 dendritic subfields, particularly in the stratum radiatum, by 14 days after reperfusion. Electron microscopy using the osmium/potassium dichromate method and electron probe microanalysis revealed selective calcium deposits within the mitochondria of degenerating dendrites at as early as 7 days after reperfusion, with subsequent complete mineralization occurring throughout the dendrites, which then coalesced to form larger mineral conglomerates with the adjacent calcifying neurites by 14 days after reperfusion. Large calcifying deposits were frequently observed at 28 days after reperfusion, when they were closely associated with or completely engulfed by astrocytes. In contrast, no prominent calcification was observed in the somata of CA1 pyramidal neurons showing the characteristic features of necrotic cell death after ischemia, although what appeared to be calcified mitochondria were noted in some degenerated neurons that became dark and condensed. Thus, our data indicate that intrahippocampal calcification after ischemic insults initially occurs within the mitochondria of degenerating dendrites, which leads to the extensive calcification that is associated with ischemic injuries. These findings suggest that in degenerating neurons, the calcified mitochondria in the dendrites, rather than in the somata, may serve as the nidus for further calcium precipitation in the ischemic hippocampus. PMID:27414398

  5. Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE)

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.

    1998-01-01

    Scanning holographic lidar receivers are currently in use in two operational lidar systems, PHASERS (Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing) and now HARLIE (Holographic Airborne Rotating Lidar Instrument Experiment). These systems are based on volume phase holograms made in dichromated gelatin (DCG) sandwiched between 2 layers of high quality float glass. They have demonstrated the practical application of this technology to compact scanning lidar systems at 532 and 1064 nm wavelengths, the ability to withstand moderately high laser power and energy loading, sufficient optical quality for most direct detection systems, overall efficiencies rivaling conventional receivers, and the stability to last several years under typical lidar system environments. Their size and weight are approximately half of similar performing scanning systems using reflective optics. The cost of holographic systems will eventually be lower than the reflective optical systems depending on their degree of commercialization. There are a number of applications that require or can greatly benefit from a scanning capability. Several of these are airborne systems, which either use focal plane scanning, as in the Laser Vegetation Imaging System or use primary aperture scanning, as in the Airborne Oceanographic Lidar or the Large Aperture Scanning Airborne Lidar. The latter class requires a large clear aperture opening or window in the aircraft. This type of system can greatly benefit from the use of scanning transmission holograms of the HARLIE type because the clear aperture required is only about 25% larger than the collecting aperture as opposed to 200-300% larger for scan angles of 45 degrees off nadir.

  6. Rapid algal toxicity assay using variable chlorophyll fluorescence for Chlorella kessleri (chlorophyta).

    PubMed

    Kvíderová, Jana

    2010-12-01

    Three methods of algal assays--the standard assay, microassay, and the proposed fluorescence assay--are compared from the point of view of reliability of EC50 detection, the minimum required time for the detection, sensitivity of individual measurement, i.e. at which cell density the particular assay can be used for EC50 estimation, and the time stability of the EC50 values. The assays were performed with green alga Chlorella kessleri strain LARG/1 growing in potassium dichromate solution in Z-medium ranging from 0.01 to 100 mg Cr L⁻¹. The inoculation cell density was set according to the standards to 10⁴ cells mL⁻¹ and according to spectrophotometer/plate reader detection limit. The average EC50 ranged from 0.096 to 0.649 mg Cr L⁻¹ and there were no significant differences in EC50 between the assay type and the inoculation methods with the exception of the significant difference between EC(c)50₇₂ (EC50 established from biomass measured as chlorophyll a concentration after 72 h of cultivation) in the standard assay and EC(r)50 (EC50 derived from growth rate) in the microassay in the standard inoculation experiment due to low variability of their values. The EC(f)50 (EC50 derived from variable fluorescence measurement) values correspond to EC50 values derived from the growth rates. Fluorescence measurement revealed the toxic effect of the chromium after 24 h of exposure at cell density of 5 x 10⁴ cells mL⁻¹, less by half than other used assay methods. The positive correlation of EC(f)50 and time was found in the standard inoculation experiment but opposite effect was observed at the spectrophotometric one. PMID:19551890

  7. The applications of populus fiber in removal of Cr(VI) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Miaomiao; Gong, Yumei; Lyu, Aichao; Liu, Yuanfa; Zhang, Hong

    2016-10-01

    The surface modification of natural materials to be applied in removal of Cr(VI) from aqueous solutions has attracted much attention. A natural sorbent for Cr(VI) based on natural populus fibers (PF) is prepared by transforming the cyano groups (AN) in polyacrylonitriles (PAN) grafted from PF into amidoxime groups (AO), which has strong ability to attract and chelate heavy metal ions. The prepared sorbent is characterized by Fourier Transform Infrared Spectra (FT-IR), thermogravimetric analysis (TGA), solid-state nuclear magnetic resonance (13C NMR) and scanning electron microscope (SEM). As potassium dichromate solution (K2Cr2O7) is used as a target solution for detecting adsorption capacity of the sorbent, the adsorption kinetics of the sorbent for chromiun is consistent with the pseudo-second-order kinetic model by analyzing the adsorption amount as a function of the sorbent dispersed duration in solution at pH = 2. The expected adsorption mechanism is that the Cr(VI) in anionic ions Cr2O72- and HCrO4- are adsorbed through electrostatic attraction but when Cr(VI) is reduced to Cr(III) by AO, the electronegative nitrogen and oxygen in AO chelate it through coordination bond. The as-prepared PF derivant with high adsorption efficiency of chromium 180.5 mg/g (3.47 mmol/g), low cost, reusability and greenly preparation process suggests that the development of natural PF as a sorbent in removal of Cr(VI) from aqueous solutions is a destined significant approach.

  8. Identifying a novel role for X-prolyl aminopeptidase (Xpnpep) 2 in CrVI-induced adverse effects on germ cell nest breakdown and follicle development in rats.

    PubMed

    Banu, Sakhila K; Stanley, Jone A; Sivakumar, Kirthiram K; Arosh, Joe A; Barhoumi, Rola; Burghardt, Robert C

    2015-03-01

    Environmental exposure to endocrine-disrupting chemicals (EDCs) is one cause of premature ovarian failure (POF). Hexavalent chromium (CrVI) is a heavy metal EDC widely used in more than 50 industries, including chrome plating, welding, wood processing, and tanneries. Recent data from U.S. Environmental Protection Agency indicate increased levels of Cr in drinking water from several American cities, which potentially predispose residents to various health problems. Recently, we demonstrated that gestational exposure to CrVI caused POF in F1 offspring. The current study was performed to identify the molecular mechanism behind CrVI-induced POF. Pregnant rats were treated with 25 ppm of potassium dichromate from Gestational Day (GD) 9.5 to GD 14.5 through drinking water, and the fetuses were exposed to CrVI through transplacental transfer. Ovaries were removed from the fetuses or pups on Embryonic Day (ED) 15.5, ED 17.5, Postnatal Day (PND) 1, PND 4, or PND 25, and various analyses were performed. Results showed that gestational exposure to CrVI: 1) increased germ cell/oocyte apoptosis and advanced germ cell nest (GCN) breakdown; 2) increased X-prolyl aminopeptidase (Xpnpep) 2, a POF marker in humans, during GCN breakdown; 3) decreased Xpnpep2 during postnatal follicle development; and 4) increased colocalization of Xpnpep2 with Col3 and Col4. We also found that Xpnpep2 inversely regulated the expression of Col1, Col3, and Col4 in all the developmental stages studied. Thus, CrVI advanced GCN breakdown and increased follicle atresia in F1 female progeny by targeting Xpnpep2. PMID:25568306

  9. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    PubMed

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface. PMID:23755692

  10. An international evaluation of the murine local lymph node assay and comparison of modified procedures.

    PubMed

    Kimber, I; Hilton, J; Dearman, R J; Gerberick, G F; Ryan, C A; Basketter, D A; Scholes, E W; Ladics, G S; Loveless, S E; House, R V

    1995-11-20

    The murine local lymph node assay is a predictive test for the identification of skin-sensitizing chemicals. The method has been the subject both of national inter-laboratory studies and of extensive comparisons with guinea pig tests. In the investigations reported here, the local lymph node assay has been evaluated further in the context of an international study comprising five independent laboratories. In addition, the influence of minor modifications to the standard assay procedure on the performance of the test has been examined. The modified procedures investigated were exposure of mice for 4 rather than 3 consecutive days, excision of lymph nodes 4 rather than 5 days after the initiation of exposure and the use of an alternative isotope. All five laboratories, irrespective of whether the standard or a modified protocol was used, were able to identify accurately, and with comparable sensitivity, potassium dichromate and 2,4-dinitrochlorobenzene as skin sensitizers. Using standard criteria, none of the laboratories recorded positive responses with methyl salicylate, a non-sensitizer. In the standard protocol, lymph nodes are pooled for each experimental group and the vigor of responses measured as a stimulation index relative to vehicle controls. A stimulation index of 3 or greater is considered to indicate skin-sensitizing potential. One further modification adopted by three of the laboratories was to analyze nodes from individual animals and, thereby, permit statistical evaluation. This allowed a direct comparison of statistical significance with the conventional stimulation index as criteria for a positive response. The data indicate that, while statistical evaluation may provide, in some instances, for small increases in sensitivity, this may be at the expense of some loss of selectivity. There are, however, insufficient data presently to draw firm conclusions regarding the relative value of statistical analysis. These studies demonstrate that the local

  11. A fetal whole ovarian culture model for the evaluation of CrVI-induced developmental toxicity during germ cell nest breakdown.

    PubMed

    Stanley, Jone A; Arosh, Joe A; Burghardt, Robert C; Banu, Sakhila K

    2015-11-15

    Prenatal exposure to endocrine disrupting chemicals (EDCs), including bisphenol A, dioxin, pesticides, and cigarette smoke, has been linked to several ovarian diseases such as premature ovarian failure (POF) and early menopause in women. Hexavalent chromium (CrVI), one of the more toxic heavy metals, is widely used in more than 50 industries. As one of the world's leading producers of Cr compounds, the U.S. is facing growing challenges in protecting human health against adverse effects of CrVI. Our recent findings demonstrated that in vivo CrVI exposure during gestational period caused POF in F1 offspring. Our current research focus is three-fold: (i) to identify the effect of CrVI on critical windows of great vulnerability of fetal ovarian development; (ii) to understand the molecular mechanism of CrVI-induced POF; (iii) to identify potential intervention strategies to mitigate or inhibit CrVI effects. In order to accomplish these goals we used a fetal whole ovarian culture system. Fetuses were removed from the normal pregnant rats on gestational day 13.5. Fetal ovaries were cultured in vitro for 12 days, and treated with or without 0.1 ppm potassium dichromate (CrVI) from culture day 2-8, which recapitulated embryonic day 14.5-20.5, in vivo. Results showed that CrVI increased germ cell/oocyte apoptosis by increasing caspase 3, BAX, p53 and PUMA; decreasing BCL2, BMP15, GDF9 and cKIT; and altering cell cycle regulatory genes and proteins. This model system may serve as a potential tool for high throughput testing of various drugs and/or EDCs in particular to assess developmental toxicity of the ovary. PMID:26348139

  12. Oxidative Stress Markers and Histological Analysis in Diverse Organs from Rats Treated with a Hepatotoxic Dose of Cr(VI): Effect of Curcumin.

    PubMed

    García-Niño, Wylly Ramsés; Zatarain-Barrón, Zyanya Lucía; Hernández-Pando, Rogelio; Vega-García, Claudia Cecilia; Tapia, Edilia; Pedraza-Chaverri, José

    2015-09-01

    Hexavalent chromium [Cr(VI)] compounds are extremely toxic and carcinogenic. Despite the vast quantity of reports about Cr(VI) toxicity, the information regarding its effects when it is intraperitoneally (i.p.) administered is still limited. In contrast, it has been shown that curcumin prevents hepatotoxicity induced by a single intraperitoneal injection of 15 mg/kg body weight (b.w.) of potassium dichromate (K2Cr2O7). This study aims to evaluate oxidative stress markers, the activity of antioxidant enzymes, and the potential histological injury in brain, heart, lung, kidney, spleen, pancreas, stomach, and intestine from rats treated with a hepatotoxic dose of K2Cr2O7 (15 mg/kg b.w.), and the effect of curcumin pretreatment. Rats were divided into four groups: control, curcumin, K2Cr2O7, and curcumin+K2Cr2O7. At the end of the treatment, plasma and ascites fluid were collected and target organs were dissected out for biochemical and histological analysis. K2Cr2O7 induced hepatotoxicity but failed to induce in all the other studied organs either oxidative or histological injury, since levels of malondialdehyde (MDA), glutathione (GSH), and the activity of superoxide dismutase (SOD), catalase (CAT), and related GSH enzymes were unchanged. As expected, curcumin was safe. Lack of K2Cr2O7-induced toxicity in those target organs could be due to the following: (1) route of administration, (2) absorption through the portal circulation, (3) lower dose than needed, (4) short time of exposure, or (5) repeated doses are required to produce damage. Thus, the intraperitoneal injection of 15 mg/kg of K2Cr2O7, that is able to induce hepatotoxicity, was unable to induce histological and oxidative damage in other target organs. PMID:25774041

  13. Is UV radiation changing the toxicity of compounds to zebrafish embryos?

    PubMed

    Almeida, Ana Rita; Andrade, Thayres S; Burkina, Viktoriia; Fedorova, Ganna; Loureiro, Susana; Soares, Amadeu M V M; Domingues, Inês

    2015-12-01

    At ecosystems level, environmental parameters such as temperature, pH, dissolved oxygen concentration and intensity of UV radiation (UVR) have an important role on the efficiency of organisms' physiological and behavioral performances and consequently on the capacity of response to contaminants. Insignificant alterations of these parameters may compromise this response. In addition, these parameters can additionally alter chemical compounds by inducing their degradation, producing thereafter other metabolites. Understanding the combined effects of chemicals and environmental parameters is absolutely necessary for an adequate prediction of risk in aquatic environments. According to this scenario, this work aims at studying the combined toxicity of UVR and three xenobiotics: the biocide triclosan (TCS), the metal chromium (as potassium dichromate, PD) and the fungicide prochloraz (PCZ). To achieve this goal zebrafish (Danio rerio) embryos (3h post fertilization (hpf)) were exposed to several concentrations of each chemical combined with different UV intensities; mortality and eggs were recorded every 24h for the all test duration (96 h). Results showed different response patterns depending on the toxicant, stress levels and duration of exposure. The combination of UVR and TCS indicated a dose ratio deviation where synergism was observed when UVR was the dominant stressor (day 2). The combination of UVR and PD presented a dose level dependency at day 3 indicating antagonism at low stress levels, changing with time where at day 4, a dose ratio deviation showed statistically that synergism occurred at higher PD concentrations. Finally, UVR combined with PCZ indicated a dose ratio at day 3 and dose level deviation at day 4 of exposure, suggesting a synergistic response when PCZ is the dominant stressor in the combination. The obtained results in this study highlighted the importance of taking into account the possible interaction of stressors and time of exposure to

  14. Efficient production of methane from artificial garbage waste by a cylindrical bioelectrochemical reactor containing carbon fiber textiles

    PubMed Central

    2013-01-01

    A cylindrical bioelectrochemical reactor (BER) containing carbon fiber textiles (CFT; BER + CFT) has characteristics of bioelectrochemical and packed-bed systems. In this study, utility of a cylindrical BER + CFT for degradation of a garbage slurry and recovery of biogas was investigated by applying 10% dog food slurry. The working electrode potential was electrochemically regulated at −0.8 V (vs. Ag/AgCl). Stable methane production of 9.37 L-CH4 · L−1 · day−1 and dichromate chemical oxygen demand (CODcr) removal of 62.5% were observed, even at a high organic loading rate (OLR) of 89.3 g-CODcr · L−1 · day−1. Given energy as methane (372.6 kJ · L−1 · day−1) was much higher than input electric energy to the working electrode (0.6 kJ · L−1 · day−1) at this OLR. Methanogens were highly retained in CFT by direct attachment to the cathodic working electrodes (52.3%; ratio of methanogens to prokaryotes), compared with the suspended fraction (31.2%), probably contributing to the acceleration of organic material degradation and removal of organic acids. These results provide insight into the application of cylindrical BER + CFT in efficient methane production from garbage waste including a high percentage of solid fraction. PMID:23497472

  15. In vitro cultivation of Hammondia heydorni: Generation of tachyzoites, stage conversion into bradyzoites, and evaluation of serologic cross-reaction with Neospora caninum.

    PubMed

    Gondim, L F P; Meyer, J; Peters, M; Rezende-Gondim, M M; Vrhovec, M G; Pantchev, N; Bauer, C; Conraths, F J; Schares, G

    2015-06-15

    Hammondia heydorni was in vitro isolated from oocysts shed by three dogs using a finite cell line from embryonal bovine heart (KH-R). The oocysts were purified and suspended in 2% potassium dichromate or 2% sulphuric acid for sporulation for 2-5 days at room temperature. The parasites were confirmed as H. heydorni by PCR using specific primers (JS4/JS5) and by negative reaction for Neospora caninum employing the primers Np6+/Np21+. H. heydorni sporulated oocysts (1 × 10(6)) from each dog were initially treated with sodium hypochlorite. For excystation of sporozoites, oocysts from one dog were lysed by ultrasound followed by incubation with 0.75% taurocholate. Excystation of sporozoites from the other two dogs was achieved by oocyst fragmentation with glass beads with no further chemical treatment. Tachyzoites were clearly seen in the cultures at three days post inoculation (dpi). Bradyzoite conversion and cyst formation were evaluated at different time points by using a polyclonal rabbit serum against a bradyzoite-specific antigen (anti-BAG1), and a rat monoclonal antibody (mAbCC2) against a cyst wall protein. Bradyzoites were firstly detected at 7 dpi. Between 18 and 21 dpi most of cultured parasites consisted of encysted bradyzoites. The H. heydorni cysts increased in size during cultivation and reached a length of up to 135 μm. The parasite was maintained in the bovine heart cells up to 4.5months. Sera from mice and sheep experimentally infected with H. heydorni oocysts reacted with H. heydorni by IFAT, but did not cross-react with N. caninum antigens using IFAT or immunoblot. These findings suggest that serological cross-reactivity between H. heydorni and N. caninum seems to be of minor importance. PMID:25887985

  16. Seasonal prevalence of gastrointestinal parasites in desi fowl (Gallus gallus domesticus) in and around Gannavaram, Andhra Pradesh.

    PubMed

    Sreedevi, C; Jyothisree, Ch; Rama Devi, V; Annapurna, P; Jeyabal, L

    2016-09-01

    A study was carried out to know the prevalence of gastrointestinal parasites in desi fowl in and nearby villages of Gannavaram, Andhra Pradesh for a period of 1 year. Screening of 492 samples comprising faecal samples and gastrointestinal tracts from freshly slaughtered desi birds at local poultry shops and samples from post mortem examinations at NTR College of Veterinary Science, Gannavaram revealed 63.21 % of gastrointestinal parasites. Faecal samples were examined by floatation technique using salt solution and samples positive for coccidian oocysts were sporulated in 2.5 % potassium dichromate solution for species identification. Adult worms were identified after routine processing and mounting. The species identified includes Davainea proglottina, Raillietina cesticillus and Raillietina echinobothrida in cestodes (32.47 %), Ascaridia galli, Capillaria annulata, Heterakis gallinarum in nematodes (39.87 %), Eimeria tenella, Eimeria acervulina and Eimeria necatrix in Eimeria spp. (39.87 %). Ascaridia galli and R. cesticillus and A. galli and Eimeria spp. were common in mixed infection (12.86 %). Ascaridia galli was the more prevalent species. No trematode parasite was identified during the study period. Significant (p = 0.001) relationship between the seasonality and prevalence of gastrointestinal parasites was observed (χ2 = 17.46, df = 2). Data revealed high prevalence in rainy season (43.41 %) followed by summer (38.91 %) and winter (17.68 %) seasons for all parasites except for A. galli and C. annulata infections which were higher in summer season. Results indicated high prevalence of gastrointestinal parasites in desi fowl in study area emphasizing the need of improved management practices of backyard poultry. PMID:27605762

  17. Identifying a Novel Role for X-prolyl Aminopeptidase (Xpnpep) 2 in CrVI-Induced Adverse Effects on Germ Cell Nest Breakdown and Follicle Development in Rats1

    PubMed Central

    Banu, Sakhila K.; Stanley, Jone A.; Sivakumar, Kirthiram K.; Arosh, Joe A.; Barhoumi, Rola; Burghardt, Robert C.

    2015-01-01

    ABSTRACT Environmental exposure to endocrine-disrupting chemicals (EDCs) is one cause of premature ovarian failure (POF). Hexavalent chromium (CrVI) is a heavy metal EDC widely used in more than 50 industries, including chrome plating, welding, wood processing, and tanneries. Recent data from U.S. Environmental Protection Agency indicate increased levels of Cr in drinking water from several American cities, which potentially predispose residents to various health problems. Recently, we demonstrated that gestational exposure to CrVI caused POF in F1 offspring. The current study was performed to identify the molecular mechanism behind CrVI-induced POF. Pregnant rats were treated with 25 ppm of potassium dichromate from Gestational Day (GD) 9.5 to GD 14.5 through drinking water, and the fetuses were exposed to CrVI through transplacental transfer. Ovaries were removed from the fetuses or pups on Embryonic Day (ED) 15.5, ED 17.5, Postnatal Day (PND) 1, PND 4, or PND 25, and various analyses were performed. Results showed that gestational exposure to CrVI: 1) increased germ cell/oocyte apoptosis and advanced germ cell nest (GCN) breakdown; 2) increased X-prolyl aminopeptidase (Xpnpep) 2, a POF marker in humans, during GCN breakdown; 3) decreased Xpnpep2 during postnatal follicle development; and 4) increased colocalization of Xpnpep2 with Col3 and Col4. We also found that Xpnpep2 inversely regulated the expression of Col1, Col3, and Col4 in all the developmental stages studied. Thus, CrVI advanced GCN breakdown and increased follicle atresia in F1 female progeny by targeting Xpnpep2. PMID:25568306

  18. Redox Viscosity of Iron Rich Silicate Melts - Martian Mantle Analogues.

    NASA Astrophysics Data System (ADS)

    Dingwell, D. B.

    2004-12-01

    The dependence of shear viscosity on the oxidation state of ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace. Two different simple Fe-bearing systems have been studied to date: (i) anorthite-diopside eutectic composition (AnDi) with variable amount of Fe (up to 20 wt%) as a basalt analogue and (ii) sodium disilicate (NS2 up to 30 wt % Fe). In addition, the compositional range has been extended to include the more complex SNC meteorite composition, a composition more relevant to Mars. The measurements were performed under air, CO2 and CO2-CO mixture at 1 atm and in a temperature range of 1300 to 1350 \\ºC. The experimental procedure involve a continuous measurement of viscosity during stepwise reduction state. The melt was reduced by flowing CO2 and then successively reducing mixtures of CO2-CO through the alumina muffle tube. Gas flow rates were electronically controlled using Tylan mass flow controllers and oxygen fugacity was directly measured using a sensor and calculated with Nernst equation. The composition and oxidation state of the melt was monitored by obtaining a melt sample after each redox equilibrium step. The melts were sampled by dipping an alumina rod into the sample and drawing out a drop of liquid, which was then plunged into water for quenching. The resulting glasses were analyzed by electron microprobe, and the volumetric potassium dichromate titration were employed to determine FeO. In addition, the redox dependence of viscosity of our samples have been compared with data from literature (Mysen et al. 1985, Dingwell and Virgo, 1988; Dingwell 1989, Dingwell 1991). The viscosity of all melts investigated herein decreases with melt reduction. The viscosity decrease is, in general, a nonlinear function of oxidation state expressed as Fe2+/Fetot and can be fitted using logarithmic equation.

  19. Ecotoxicological studies with newly hatched larvae of Concholepas concholepas (Mollusca, Gastropoda): bioassay with secondary-treated kraft pulp mill effluents.

    PubMed

    Manríquez, Patricio H; Llanos-Rivera, Alejandra; Galaz, Sylvana; Camaño, Andrés

    2013-12-01

    The Chilean abalone or "loco" (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification. PMID:24099753

  20. Patch test results in patients with allergic contact dermatitis in the Podlasie region

    PubMed Central

    Bacharewicz, Joanna; Pawłoś, Anna

    2013-01-01

    Introduction The aim of the study was to provide current data on the incidence of allergy to various contact allergens in patients with allergic contact eczema and the analysis of selected socio-demographic data of the patients. Material and methods The study included 1532 patients (1010 women and 522 men) treated for allergic contact dermatitis at the Department of Dermatology and Venereology and at the Dermatology Outpatient Clinic in Bialystok in 2007–2011. The assessment of selected demographic data and skin lesions was based on the MOAHFLA index, while the results of patch tests were analyzed with modified Baseline European Series consisting of 31 allergens. Results In the group of patients with eczema, 34.1% were men, and 55% of all respondents were people over 40 years of age. The occupational character of skin lesions was found in 22.5%. Most frequently (38.9%) skin lesions were localized on the hands, rarely involved legs (3.98%). Atopic dermatitis was diagnosed in 4.5% of patients. The ten most frequent allergens were: nickel sulfate (24%), cobalt chloride (15.3%), fragrance mix (8.25%), potassium dichromate (6.8%), balsam of Peru (5.5%), neomycin (4.42%), paraphenylenediamine (3.85%), Quatermium-15 (2.1%), detreomycin (1.83%) and budesonide (1.44% of tested patients). Conclusions Frequent allergy to detreomycin indicates the need of patch testing for this allergen of all examined patients with allergic contact dermatitis. The increased frequency of the nickel allergy is a worrying problem and indicates the need for education about the risk factors for nickel allergy development and the implementation of appropriate legal regulations. PMID:24493997

  1. Dispersion modeling of particulate matter containing hexavalent chromium during high winds in southern Iraq.

    PubMed

    Zannetti, Paolo; Daly, Aaron D; Freedman, Frank R

    2015-02-01

    The aim of this paper is to describe a scientific methodology (i.e., the combination of different well-established modeling techniques) and its application to a real case scenario of contaminated dust emissions in high winds. This scenario addresses potential air pollution problems at the water treatment plant (WTP) at Qarmat-Ali, Basra, Iraq, during 2003. Workplace practices at the WTP before 2003 resulted in sodium dichromate contamination in the area. Looting at the site in early 2003 also contributed to this contamination. Individuals who were assigned to provide security at the site in 2003 have claimed adverse health effects caused by exposure to dust containing hexavalent chromium [Cr(VI)]. This report presents our modeling study with respect to these claims in relation to (1) amount of Cr(VI) present in the soil, (2) wind erosion episodes, and (3) possible long-term (e.g., annual average) Cr(VI) concentrations inhaled by different people while at the site. Our modeling approach included (1) the analysis of Cr(VI) soil measurements to assess the degree of contamination in different areas of the plant at different times; (2) the use of DUSTRAN model equations to calculate the emission rate of particulate matter (PM) less than 10 µm in diameter (PM10) during high-wind episodes; (3) the use of the U.S. Environmental Protection Agency (EPA) AERMOD modeling system to estimate Cr(VI) concentrations at the site; and (4) the calculation of modeling results in the form of both contour lines of average Cr(VI) concentrations at the site, and specific concentration values for selected individuals, based upon their recollection of their visits to the site. PMID:25947053

  2. Chromium (VI) Inhibits Heme Oxygenase-1 Expression In Vivo and in Arsenic-Exposed Human Airway Epithelial Cells

    PubMed Central

    O’HARA, KIMBERLEY A.; NEMEC, ANTONIA A.; ALAM, JAWED; KLEI, LINDA R.; MOSSMAN, BROOKE T.; BARCHOWSKY, AARON

    2015-01-01

    Inhaled hexavalent chromium (Cr(VI)) promotes lung injury and pulmonary diseases through poorly defined mechanisms. One hypothesis for this lung pathogenesis is that Cr(VI) silences induction of cytoprotective genes, such as heme oxygenase-1 (HO-1), whose total lung mRNA levels were reduced 21 days after nasal instillation of potassium dichromate in C57BL/6 mice. To investigate the mechanisms for this inhibition, Cr(VI) effects on basal and arsenic (As(III))-induced HO-1 expression were examined in cultured human bronchial epithelial (BEAS-2B) cells. An effect of Cr(VI) on the low basal HO-1 mRNA and protein levels in BEAS-2B cells was not detectible. In contrast, Cr(VI) added to the cells before As(III), but not simultaneously with As(III), attenuated As(III)-induced HO-1 expression. Transient transfection with luciferase reporter gene constructs controlled by the full length ho-1 promoter or deletion mutants demonstrated that this inhibition occurred in the E1 enhancer region containing critical antioxidant response elements (ARE). Cr(VI) pretreatment inhibited As(III)-induced activity of a transiently expressed reporter construct regulated by three ARE tandem repeats. The mechanism for this Cr(VI)-attenuated transactivation appeared to be Cr(VI) reduction of the nuclear levels of the transcription factor Nrf2 and As(III)-stimulated Nrf2 transcriptional complex binding to the ARE cis element. Finally, exposing cells to Cr(VI) prior to co-exposure with As(III) synergized for apoptosis and loss of membrane integrity. These data suggest that Cr(VI) silences induction of ARE-driven genes required for protection from secondary insults. The data also have important implications for understanding the toxic mechanisms of low level, mixed metal exposures in the lung. PMID:16775837

  3. A case study to optimise and validate the brine shrimp Artemia franciscana immobilisation assay with silver nanoparticles: The role of harmonisation.

    PubMed

    Kos, Monika; Kahru, Anne; Drobne, Damjana; Singh, Shashi; Kalčíková, Gabriela; Kühnel, Dana; Rohit, Rekulapelly; Gotvajn, Andreja Žgajnar; Jemec, Anita

    2016-06-01

    Brine shrimp Artemia sp. has been recognised as an important ecotoxicity and nanotoxicity test model organism for salt-rich aquatic environments, but currently there is still no harmonised testing protocol which would ensure the comparable results for hazard identification. In this paper we aimed to design the harmonised protocol for nanomaterial toxicity testing using Artemia franciscana and present a case study to validate the protocol with silver nanoparticles (AgNPs). We (i) revised the existing nanotoxicity test protocols with Artemia sp. (ii) optimised certain methodological steps based on the experiments with AgNPs and potassium dichromate (K2Cr2O7) as a soluble reference chemical and (iii) tested the optimised protocol in an international inter-laboratory exercise conducted within the EU FP7 NanoValid project. The intra- and inter-laboratory reproducibility of the proposed protocol with a soluble reference chemical K2Cr2O7 was good, which confirms the suitability of this assay for conventional chemicals. However, the variability of AgNPs toxicity results was very high showing again that nanomaterials are inherently challenging for toxicity studies, especially those which toxic effect is linked to shed metal ions. Among the identified sources for this variability were: the hatching conditions, the type of test plate incubation and the illumination regime. The latter induced variations assumingly due to the changes in bioavailable silver species concentrations. Up to our knowledge this is the first inter-laboratory comparison of the Artemia sp. toxicity study involving nanomaterials. Although the inter-laboratory exercise revealed poor repeatability of AgNPs toxicity results, this study provides valuable information regarding the importance of harmonisation of all steps in the test procedure. Also, the presented AgNPs toxicity case study may serve as a platform for further validation steps with other types of NMs. PMID:26895539

  4. Polycyclic aromatic hydrocarbons and black carbon in intertidal sediments of China coastal zones: Concentration, ecological risk, source and their relationship.

    PubMed

    Li, Xiaofei; Hou, Lijun; Li, Ye; Liu, Min; Lin, Xianbiao; Cheng, Lv

    2016-10-01

    Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) have attracted many attentions, especially in the coastal environments. In this study, spatiotemporal distributions of PAHs and BC, and the correlations between BC and PAHs were investigated in the intertidal sediments of China coastal zones. BC in sediments was measured through dichromate oxidation (BCCr) and thermal oxidation (BCCTO). The concentrations of BCCr in the intertidal sediments ranged between 0.61 and 6.32mgg(-1), while BCCTO ranged between 0.57 and 4.76mgg(-1). Spatial variations of δ(13)C signatures in TOC and BC were observed, varying from -21.13‰ to -24.87‰ and from -23.53‰ to -16.78‰, respectively. PAH contents of sediments ranged from 195.9 to 4610.2ngg(-1) in winter and 98.2 to 2796.5ngg(-1) in summer, and significantly seasonal variations were observed at most sampling sites. However, the results of potential toxicity assessment indicated low ecological risk in the intertidal sediments of China coastal zones. Greater concentrations of PAHs measured in the sediments of estuarine environments indicated that rivers runoff may have been responsible for the higher PAH pollution levels in the intertidal sediments of China coastal zones. Pearson's correlation analysis suggested that pyrogenic compounds of PAH were significantly related to BC, due to that both BC and these compounds derived mainly from the combustion process of fossil fuels and biomass. Overall, increasing energy consumptions caused by anthropogenic activities can contribute more emissions of BC as well as PAHs and thus improve the importance of BC in indicating pyrogenic compounds of PAHs in the intertidal sediments of China coastal zones. PMID:27266522

  5. Exploratory study of coal-conversion chemistry. Quarterly report No. 9, March 20, 1980-June 19, 1980. [Hydroxydiphenylmethane, diphenylether, diphenymethane

    SciTech Connect

    McMillen, Donald F.; Ogier, Walter C.

    1980-11-19

    This report describes work accomplished under two tasks: Task A, Mechanism of Cleavage of Key Bond Types Present in Coals, and Task B, Catalysis of Conversion in CO-H/sub 2/O Systems. Under Task A, the very effective catalysis of carbon-carbon bond cleavage by iron oxides in hydroxydiphenylmethane structures has been further characterized. An electron-transfer mechanism offers the most likely explanation of the observations that (1) alumina and silica-alumina surfaces are less active catalysts than Fe/sub 3/O/sub 4/, (2) meta-hydroxydiphenylmethane is almost as subject to catalysis as para-hydroxydiphenylmethane, (3) diphenyl ether is less subject to Fe/sub 3/O/sub 4/ catalysis than diphenylmethane, and (4) ortho-methoxydiphenylmethane exhibits the same susceptibility to Fe/sub 3/O/sub 4/ catalysis as ortho-hydroxydiphenylmethane. Under Task B, this quarter we have completed the survey of possible metal catalysts present in the Hastelloy C autoclave. We have found that coal conversion in CO-H/sub 2/O systems is effective when metal oxides such as MoO/sub 4//sup =/, Cr/sub 2/O/sub 7//sup =/, and MnO/sub 4//sup -/ are used as catalysts, but there is less or no coal conversion with FeCl/sub 3/ or Ni(CH/sub 3/COO)/sub 2/. While studying the fate of the catalyst after the reaction, we have isolated formate in the water-soluble fraction. This important information could help us in studying the role of formate in coal conversion. During this quarter, we have also studied the influence of reaction time and fresh CO on coal conversion in the presence of a catalyst. A striking result of 67% of benzene-soluble materials was obtained with an equivalent of 6000 ppM of Cr as sodium dichromate.

  6. Mechanistic insight into chromium(VI) reduction by oxalic acid in the presence of manganese(II).

    PubMed

    Wrobel, Katarzyna; Corrales Escobosa, Alma Rosa; Gonzalez Ibarra, Alan Alexander; Mendez Garcia, Manuel; Yanez Barrientos, Eunice; Wrobel, Kazimierz

    2015-12-30

    Over the past few decades, reduction of hexavalent chromium (Cr(VI)) has been studied in many physicochemical contexts. In this research, we reveal the mechanism underlying the favorable effect of Mn(II) observed during Cr(VI) reduction by oxalic acid using liquid chromatography with spectrophotometric diode array detector (HPLC-DAD), nitrogen microwave plasma atomic emission spectrometry (HPLC-MP-AES), and high resolution mass spectrometry (ESI-QTOFMS). Both reaction mixtures contained potassium dichromate (0.67 mM Cr(VI)) and oxalic acid (13.3mM), pH 3, one reaction mixture contained manganese sulfate (0.33 mM Mn(II)). In the absence of Mn(II) only trace amounts of reaction intermediates were generated, most likely in the following pathways: (1) Cr(VI)→ Cr(IV) and (2) Cr(VI)+Cr(IV)→ 2Cr(V). In the presence of Mn(II), the active reducing species appeared to be Mn(II) bis-oxalato complex (J); the proposed reaction mechanism involves a one-electron transfer from J to any chromium compound containing CrO bond, which is reduced to CrOH, and the generation of Mn(III) bis-oxalato complex (K). Conversion of K to J was observed, confirming the catalytic role of Mn(II). Since no additional acidification was required, the results obtained in this study may be helpful in designing a new, environmentally friendly strategy for the remediation of environments contaminated with Cr(VI). PMID:26177490

  7. High-efficiency cadmium and zinc-telluride-based thin-film solar cells

    SciTech Connect

    Rohatgi, A.; Sudharsanan, R.; Ringel, S. )

    1992-02-01

    This report describes research into polycrystalline CdTe solar cells grown by metal-organic chemical vapor deposition. Efficiencies of {approximately}10% were achieved using both p-i-n and p-n structures. A pre-heat treatment of CdS/SnO{sub 2}/glass substrates at 450{degrees}C in hydrogen atmosphere prior to the CdTe growth was found to be essential for high performance because this heat treatment reduces oxygen-related defects from the CdS surface. However, this treatment also resulted in a Cd-deficient CdS surface, which may in part limit the CdTe cell efficiency to 10% due to Cd vacancy-related interface defects. Preliminary model calculations suggest that removing these states can increase the cell efficiency from 10% to 13.5%. Photon absorption in the CdS film also limits the cell performance, and eliminating this loss mechanism can result in CdTe efficiencies in excess of 18%. Polycrystalline, 1.7-e, CdZnTe films were also grown for tandem-cell applications. CdZnTe/CdS cells processed using the standard CdTe cell fabrication procedure resulted in 4.4% efficiency, high series resistance, and a band-gap shift to 1.55 eV. The formation of Zn-O at and near the CdZnTe surface is the source of high contact resistance. A saturated dichromate each prior to contact deposition was found to solve the contact resistance problem. The CdCl{sub 2} treatment was identified as the cause of the observed band-gap shift due to the preferred formation of ZnCl{sub 2}. 59 refs.

  8. Stability of sulfonamides, nitrofurans, and chloramphenicol residues in preserved raw milk samples measured by liquid chromatography.

    PubMed

    Noa, Mario; Perez, Norima; Gutierrez, Rey; Escobar, Irma; Diaz, Gilberto; Vega, Salvador; Prado, Guadalupe; Urban, Georgina

    2002-01-01

    A stability study was made of 10 antimicrobials: 6 sulfonamides, 3 nitrofurans, and chloramphenicol residues in raw milk samples preserved with 0.1 % potassium dichromate (K2Cr2O7) and 0.05% mercuric bichloride (HgCl2) during cold storage for 7 days. Preserved milk samples fortified with 50 ppb of each antimicrobial were analyzed by liquid chromatography (modified AOAC Method 993.32). Drugs were extracted with chloroform-acetone after solvent evaporation residues were dissolved with aqueous sodium acetate buffer solution (0.02M, pH 4.8), and fat was removed with hexane. Sulfonamides and chloramphenicol were detected at 275 nm (UV) by using a gradient system of sodium acetate buffer solution-acetonitrile starting at 95 + 5 (v/v) and finishing at 80 + 20 (v/v). Nitrofurans were detected at 375 nm (UV) isocratically with sodium acetate buffer solution-acetonitrile (80 + 20, v/v). Residues stability was measured through recovery data. Sulfamethoxazole, sulfachloropyridazine, nitrofurazone, furazolidone, and furaltadone residues remained stable in the presence of either preservative for 7 days. Sulfamethazine and chloramphenicol were not affected by K2Cr2O7, but had significant losses (p <0.05) when HgCl2 was used: 26.2 and 13.4%, respectively. Average recoveries of sulfamonomethoxine, sulfamerazine, and sulfathiazole significantly decreased by Day 7, with losses of 17.1, 17.2, and 23.2% for K2Cr2O7, and 23.3, 20.7, and 48.0% for HgCl2, respectively. During 5 days of cold storage all antimicrobials tested, except sulfathiazole, remained stable in milk samples preserved with 0.1 % K2Cr2O7 or 0.05% HgCl2. PMID:12477207

  9. Genomic and proteomic profiling of responses to toxic metals in human lung cells.

    PubMed Central

    Andrew, Angeline S; Warren, Amy J; Barchowsky, Aaron; Temple, Kaili A; Klei, Linda; Soucy, Nicole V; O'Hara, Kimberley A; Hamilton, Joshua W

    2003-01-01

    Examining global effects of toxic metals on gene expression can be useful for elucidating patterns of biological response, discovering underlying mechanisms of toxicity, and identifying candidate metal-specific genetic markers of exposure and response. Using a 1,200 gene nylon array, we examined changes in gene expression following low-dose, acute exposures of cadmium, chromium, arsenic, nickel, or mitomycin C (MMC) in BEAS-2B human bronchial epithelial cells. Total RNA was isolated from cells exposed to 3 M Cd(II) (as cadmium chloride), 10 M Cr(VI) (as sodium dichromate), 3 g/cm2 Ni(II) (as nickel subsulfide), 5 M or 50 M As(III) (as sodium arsenite), or 1 M MMC for 4 hr. Expression changes were verified at the protein level for several genes. Only a small subset of genes was differentially expressed in response to each agent: Cd, Cr, Ni, As (5 M), As (50 M), and MMC each differentially altered the expression of 25, 44, 31, 110, 65, and 16 individual genes, respectively. Few genes were commonly expressed among the various treatments. Only one gene was altered in response to all four metals (hsp90), and no gene overlapped among all five treatments. We also compared low-dose (5 M, noncytotoxic) and high-dose (50 M, cytotoxic) arsenic treatments, which surprisingly, affected expression of almost completely nonoverlapping subsets of genes, suggesting a threshold switch from a survival-based biological response at low doses to a death response at high doses. PMID:12760830

  10. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    PubMed

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  11. Potential contributions of asphalt and coal tar to black carbon quantification in urban dust, soils, and sediments

    USGS Publications Warehouse

    Yang, Y.; Mahler, B.J.; Van Metre, P.C.; Ligouis, B.; Werth, C.J.

    2010-01-01

    Measurements of black carbon (BC) using either chemical or thermal oxidation methods are generally thought to indicate the amount of char and/or soot present in a sample. In urban environments, however, asphalt and coal-tar particles worn from pavement are ubiquitous and, because of their pyrogenic origin, could contribute to measurements of BC. Here we explored the effect of the presence of asphalt and coal-tar particles on the quantification of BC in a range of urban environmental sample types, and evaluated biases in the different methods used for quantifying BC. Samples evaluated were pavement dust, residential and commercial area soils, lake sediments from a small urban watershed, and reference materials of asphalt and coal tar. Total BC was quantified using chemical treatment through acid dichromate (Cr2O7) oxidation and chemo-thermal oxidation at 375??C (CTO-375). BC species, including soot and char/charcoal, asphalt, and coal tar, were quantified with organic petrographic analysis. Comparison of results by the two oxidation methods and organic petrography indicates that both coal tar and asphalt contribute to BC quantified by Cr2O7 oxidation, and that coal tar contributes to BC quantified by CTO-375. These results are supported by treatment of asphalt and coal-tar reference samples with Cr2O7 oxidation and CTO-375. The reference asphalt is resistant to Cr2O7 oxidation but not to CTO-375, and the reference coal tar is resistant to both Cr2O7 oxidation and CTO-375. These results indicate that coal tar and/or asphalt can contribute to BC measurements in samples from urban areas using Cr2O7 oxidation or CTO-375, and caution is advised when interpreting BC measurements made with these methods. ?? 2010 Elsevier Ltd.

  12. Estimation of blood alcohol concentration in deaths due to roadside accidents.

    PubMed

    Arora, Puneet; Chanana, Ashok; Tejpal, Hakumat R

    2013-05-01

    Like any other disease, accidents too are caused by interaction between agent, host, and environment. Human factors include age, (accidents most common between 10 and 24 years), sex, education, medical conditions (heart attack, impaired vision), fatigue, influence of alcohol and other drugs, lack of bodily protection (like helmets, seat belts) and psychosocial factors like lack of experience, impulsiveness, aggressiveness, defective judgment and delay in decisions. Drunken driving is an important risk factor in causing accidents. This study was focused on the status of alcohol consumption in relation with roadside accidents in northern India in the region of Amritsar. The present study was carried out in 100 cases alleged to have died of roadside accident and brought to the mortuary attached to the Department of Forensic Medicine and Toxicology, Government Medical College, Amritsar for autopsy examination. Blood samples were collected from the femoral vein and were tested for the presence of alcohol with steam distillation and titration method using potassium dichromate and sulfuric acid. In the present study, 23% of the fatal driver/pedestrian victims of roadside accidents were found to have consumed alcohol before accident. Most of the victims of road accident were from the age group 21-30 and 31-40 years. Most of the accidents occurred on straight roads instead of bends or intersections, more during daytime and weekends. 57% of the blood alcohol positives were between 100 mg% and 149 mg%. Majority of the victims of roadside accidents were motorcyclists and the striking vehicles were trucks and buses causing head & neck injuries in most of the victims. Death occurred within a few minutes in most of the cases. PMID:23622478

  13. Synthesis, interactions, molecular structure, biological properties and molecular docking studies on Mn, Co, Zn complexes containing acetylacetone and pyridine ligands with DNA duplex.

    PubMed

    Thamilarasan, V; Sengottuvelan, N; Stalin, N; Srinivasan, P; Chakkaravarthi, G

    2016-07-01

    Three metal complexes (1-3) of the type [Mn(acac)2(py)·H2O] (1), [Co(acac)2(py)·H2O] (2) and [Zn(acac)2(py)·H2O] (3), [Where acac=acetylacetone, py=pyridine] were synthesized and characterized by spectral (UV-vis, FT-IR, ESI-mass) analysis. The structure of complex 2 has been determined by single crystal X-ray diffraction studies and the configuration of ligand-coordinated to metal(II) ion was well described as distorted octahedral coordination geometry. The interaction of the complexes with CT-DNA has been explored by absorption, fluorescence, circular dichromism spectroscopy, viscosity measurements and molecular docking studies. The intrinsic binding constant Kb of complexes 1-3 with CT-DNA obtained from UV-vis absorption spectral studies were 2.1×10(4), 2.1×10(5) and 1.98×10(4)M(-1), respectively, which revealed that the complexes could interact with CT-DNA through groove binding. The results indicated that the complexes (1-3) were able to bind to DNA with different binding affinity, in the order: 2>1>3. The interaction of the compounds with bovine serum albumins were also investigated using fluorescence methods and the gel electrophoresis assay demonstrates weak cleavage ability of the pBR322 plasmid DNA in the presence of the metal complexes (1-3) with various activators. Further, the in vitro cytotoxic effect of the complexes were examined on cancerous cell line, with human breast cancer cells MCF-7. PMID:27104666

  14. Bioavailability assessment of toxic metals using the technique "acid-volatile sulfide (AVS)-simultaneously extracted metals (SEM)" in marine sediments collected in Todos os Santos Bay, Brazil.

    PubMed

    Silva, Jucelino B; Nascimento, Rodrigo A; de Oliva, Sergio T; de Oliveira, Olívia M C; Ferreira, Sergio L C

    2015-10-01

    This paper reports the bioavailability of the metals (cadmium, copper, zinc, lead, and nickel) in sediment samples collected in seven stations from the São Paulo Estuary, Todos os Santos Bay, Brazil. The bioavailability was determined by employing the technique "acid-volatile sulfide (AVS) and simultaneously extracted metal (SEM)". The elements cadmium, copper, lead, and zinc were determined using differential pulse anodic stripping voltammetry (DPASV), while nickel was quantified utilizing electrothermal atomic absorption spectrometry (ET AAS). The accuracy of these methods was confirmed using a certified reference material of estuarine sediment (NIST 1646). The sulfide was quantified using potentiometry with selective electrode and the organic matter determination employing an indirect volumetric method using potassium dichromate and iron(II) sulfate solutions. The bioavailability of the metals was estimated by relationship between the concentration of AVS and the sum of the concentrations of the simultaneously extracted metals (ΣSEM), considering a significant toxicity when (ΣSEM)/(AVS) is higher than 1. The bioavailability values in the seven stations studied varied from 0.93 to 1.31 (June, 2014) and from 0.34 to 0.58 (September, 2014). These results demonstrated a critical condition of toxicity (bioavailability >1) in six of the seven sediment samples collected during the rainy season (June, 2014). In the other period (September, 2014), the bioavailability was always lower than 1 for all sediment samples collected in the seven stations. The individual values of the concentrations of the five metals were compared with the parameters PEL (probable effects level) and TEL (threshold effects level), which are commonly employed for characterization of ecological risk in environmental systems. This comparison revealed that all metals have concentrations lower than the PEL and only zinc and lead in some stations have contents higher than the TEL. The

  15. Magnetic solid-phase extraction of protein with deep eutectic solvent immobilized magnetic graphene oxide nanoparticles.

    PubMed

    Xu, Kaijia; Wang, Yuzhi; Ding, Xueqin; Huang, Yanhua; Li, Na; Wen, Qian

    2016-02-01

    As a new type of green solvent, four kinds of choline chloride (ChCl)-based deep eutectic solvents (DESs) have been synthesized, and then a core-shell structure magnetic graphene oxide (Fe3O4-NH2@GO) nanoparticles have been prepared and coated with the ChCl-based DESs. Magnetic solid-phase extraction (MSPE) based Fe3O4-NH2@GO@DES was studied for the first time for the extraction of proteins. The characteristic results of vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM) indicated the successful preparation of Fe3O4-NH2@GO@DES. The concentrations of proteins in studies were determined by a UV-vis spectrophotometer. The advantages of Fe3O4-NH2@GO@DES in protein extraction were compared with Fe3O4-NH2@GO and Fe3O4-NH2, and Fe3O4-NH2@GO@ChCl-glycerol was selected as the suitable extraction solvent. The influence factors of the extraction process such as the pH value, the temperature, the extraction time, the concentration of protein and the amount of Fe3O4-NH2@GO@ChCl-glycerol were evaluated. Desorption experimental result showed 98.73% of BSA could be eluted from the solid extractant with 0.1 mol/L Na2HPO4 solution contained 1 mol/L NaCl. Besides, the conformation of BSA was not changed during the elution by the investigation of circular dichromism (CD) spectra. Furthermore, the analysis of real sample demonstrated that the prepared magnetic nanoparticles did have extraction ability on proteins in bovine whole blood. PMID:26653436

  16. Ultrastructural investigation of microcalcification and the role of oxygen-glucose deprivation in cultured rat hippocampal slices.

    PubMed

    Riew, Tae-Ryong; Kim, Hong Lim; Shin, Yoo-Jin; Park, Joo-Hee; Pak, Ha-Jin; Lee, Mun-Yong

    2015-10-01

    Intracellular calcium accumulation is associated with cell death in several neuropathological disorders including brain ischemia, but the exact mechanisms of calcification need to be clarified. We used organotypic hippocampal slice culture - cultures subjected to oxygen-glucose deprivation (OGD) mimicking the in vivo situation to investigate the events underlying ectopic calcification. Alizarin red staining indicating calcium deposition was observed in the cornu ammonis (CA)1 and dentate gyrus regions in control hippocampal slices despite no specific labeling for cell death markers. Electron microscopy using the osmium/potassium dichromate method revealed scattered degenerated cells throughout the normally appearing CA1 region. They contained electron-dense precipitates within mitochondria, and electron probe microanalysis confirmed that they were calcifying mitochondria. Selective calcium deposition was noted within, but not beyond, mitochondria in these mineralized cells. They showed ultrastructural features of non-necrotic, non-apoptotic cell death and retained their compact ultrastructure, even after the majority of mitochondria were calcified. Unexpectedly, no intracellular calcification was noted in necrotic CA1 pyramidal cells after OGD, and there was no progression of calcification in OGD-lesioned slices. In addition, mineralized cells in both control and OGD-lesioned slices were closely associated with or completely engulfed by astrocytes but not microglia. These astrocytes were laden with heterogeneous cytoplasmic inclusions that appeared to be related with their phagocytic activity. These data demonstrate that microcalcification specifically associated with mitochondria might lead to a novel type of cell death and suggest that astrocytes may be involved in the phagocytosis of these mineralized cells and possibly in the regulation of ectopic calcification. PMID:26188662

  17. Effect of hexavalent chromium on drug-metabolizing enzymes in male domesticated rabbits.

    PubMed

    Anjum, F; Shakoori, A R; Gorrod, J W

    1996-01-01

    We studied the effect of chromium on the drug-metabolizing enzymes (DME) in male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The activities of cytochrome P-450 (183%), aniline hydroxylase (ANH, 265%), acetanilide hydroxylase (ACH, 160%), benzphetamine demethylase (BD, 112%), aminopyrine demethylase (AD, 97%), N,N,-dimethyl aniline demethylase (DAD, 72%), and cytochrome-c-reductase (100%) were increased after PB treatment. The activities of cytochrome b5 and N,N,-dimethyl aniline N-oxide (DAO) were, however, decreased 79% and 47%, respectively. Most of the DME remained unaffected after PM treatment except for the increase in ANH (55%), ACH (56%), and BD (16%). Potassium dichromate administered to rabbits at a dose of 8 mg/kg body weight/day for 5 days resulted in an increase in the activities of ANH (108%), BD (76%), AD (25%), and DAD (49%), while that of cytochrome b5 and DAO were inhibited 81 and 77%, respectively. There was no effect on the activities of cytochrome P-450, ACH, and cytochrome-c-reductase. Chromium, administered to PB-pretreated animals decreased the activities of ANH (41%), ACH (35%), BD (34%), AD (30%), DAD (51%), cytochrome-c-reductase (72%), and DAO (62%). Other enzymes remained unaffected. When administered to PM-pretreated animals, the activities of ANH, BD, AD, and DAD increased 34, 69, 24 and 54%, respectively, whereas activities of cytochrome b5 and DAO were decreased 96 and 68%, respectively. All other DME remained unaffected. PMID:9037263

  18. Biodegradability of fluorinated fire-fighting foams in water.

    PubMed

    Bourgeois, A; Bergendahl, J; Rangwala, A

    2015-07-01

    Fluorinated fire-fighting foams may be released into the environment during fire-fighting activities, raising concerns due to the potential environmental and health impacts for some fluorinated organics. The current study investigated (1) the biodegradability of three fluorinated fire-fighting foams, and (2) the applicability of current standard measures used to assess biodegradability of fluorinated fire-fighting foams. The biodegradability of three fluorinated fire-fighting foams was evaluated using a 28-day dissolved organic carbon (DOC) Die-Away Test. It was found that all three materials, diluted in water, achieved 77-96% biodegradability, meeting the criteria for "ready biodegradability". Defluorination of the fluorinated organics in the foam during biodegradation was measured using ion chromatography. It was found that the fluorine liberated was 1-2 orders of magnitude less than the estimated initial amount, indicating incomplete degradation of fluorinated organics, and incomplete CF bond breakage. Published biodegradability data may utilize biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) metrics to quantify organics. COD and TOC of four fluorinated compounds were measured and compared to the calculated carbon content or theoretical oxygen demand. It was found that the standard dichromate-based COD test did not provide an accurate measure of fluorinated organic content. Thus published biodegradability data using COD for fluorinated organics quantification must be critically evaluated for validity. The TOC measurements correlated to an average of 91% of carbon content for the four fluorinated test substances, and TOC is recommended for use as an analytical parameter in fluorinated organics biodegradability tests. PMID:25813673

  19. Genome-wide gene expression effects in B6C3F1 mouse intestinal epithelia following 7 and 90 days of exposure to hexavalent chromium in drinking water

    SciTech Connect

    Kopec, Anna K.; Kim, Suntae; Forgacs, Agnes L.; Zacharewski, Timothy R.; Proctor, Deborah M.; Harris, Mark A.; Haws, Laurie C.; Thompson, Chad M.

    2012-02-15

    Chronic administration of high doses of hexavalent chromium [Cr(VI)] as sodium dichromate dihydrate (SDD) elicits alimentary cancers in mice. To further elucidate key events underlying tumor formation, a 90-day drinking water study was conducted in B6C3F1 mice. Differential gene expression was examined in duodenal and jejunal epithelial samples following 7 or 90 days of exposure to 0, 0.3, 4, 14, 60, 170 or 520 mg/L SDD in drinking water. Genome-wide microarray analyses identified 6562 duodenal and 4448 jejunal unique differentially expressed genes at day 8, and 4630 and 4845 unique changes, respectively, in the duodenum and jejunum at day 91. Comparative analysis identified significant overlap in duodenal and jejunal differential gene expression. Automated dose–response modeling identified > 80% of the differentially expressed genes exhibited sigmoidal dose–response curves with EC{sub 50} values ranging from 10 to 100 mg/L SDD. Only 16 genes satisfying the dose-dependent differential expression criteria had EC{sub 50} values < 10 mg/L SDD, 3 of which were regulated by Nrf2, suggesting oxidative stress in response to SDD at low concentrations. Analyses of differentially expressed genes identified over-represented functions associated with oxidative stress, cell cycle, lipid metabolism, and immune responses consistent with the reported effects on redox status and histopathology at corresponding SDD drinking water concentrations. Collectively, these data are consistent with a mode of action involving oxidative stress and cytotoxicity as early key events. This suggests that the tumorigenic effects of chronic Cr(VI) oral exposure likely require chronic tissue damage and compensatory epithelial cell proliferation. Highlights: ► Mouse small intestine gene expression is highly responsive to hexavalent chromium [Cr(VI)]. ► Cr(VI) elicits more differential gene expression after 7 days of exposure than 90 days of exposure. ► Oral exposure to Cr(VI) leads to

  20. Renoprotective Effect of Lactoferrin against Chromium-Induced Acute Kidney Injury in Rats: Involvement of IL-18 and IGF-1 Inhibition.

    PubMed

    Hegazy, Rehab; Salama, Abeer; Mansour, Dina; Hassan, Azza

    2016-01-01

    Hexavalent chromium (CrVI) is a heavy metal widely used in more than 50 industries. Nephrotoxicity is a major adverse effect of chromium poisoning. The present study investigated the potential renoprotective effect of lactoferrin (Lf) against potassium dichromate (PDC)-induced acute kidney injury (AKI) in rats. Beside, because previous studies suggest that interlukin-18 (IL-18) and insulin-like growth factor-1 (IGF-1) play important roles in promoting kidney damage, the present work aimed to evaluate the involvement of these two cytokines in PDC model of AKI and in the potential renoprotective effect of lactoferrin. Adult male albino Wistar rats were pretreated with Lf (200 mg/kg/day, p.o.) or (300 mg/kg/day, p.o.); the doses that are usually used in the experiment studies, for 14 days followed by a single dose of PDC (15 mg/kg, s.c.). PDC caused significant increase in serum urea, creatinine, and total protein levels. This was accompanied with decreased renal glutathione content, and increased renal malondialdehyde, IL-18, IL-4, nuclear factor kappa B (NFκB), IGF-1, and the phosphorylated form of forkhead box protein O1 (FoxO1) levels. Moreover, normal expression IFN-γ mRNA and enhanced expression of TNF-α mRNA was demonstrated in renal tissues. Histopathological investigations provoked deleterious changes in the renal tissues. Tubular epithelial hyperplasia and apoptosis were demonstrated immunohistochemically by positive proliferating cell nuclear antigen (PCNA), Bax, and Caspase-3 expression, respectively. Pretreatment of rats with Lf in both doses significantly corrected all previously mentioned PDC-induced changes with no significant difference between both doses. In conclusion, the findings of the present study demonstrated the involvement of oxidative stress, inflammatory reactions, tubular hyperplasia and apoptosis in PDC-induced AKI. It suggested a role of IL-18 through stimulation of IL-4-induced inflammatory pathway, and IGF-1 through triggering Fox

  1. Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh; Dong, Hailiang; Liu, Deng; Zhao, Linduo; Marts, Amy R.; Farquhar, Erik; Tierney, David L.; Almquist, Catherine B.; Briggs, Brandon R.

    2015-01-01

    Despite significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70 °C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations using 1,5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to 1.9 μM h-1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature subsurface radioactive waste disposal

  2. In-situ determination of the oxidation state of iron in Fe-bearing silicate melts

    NASA Astrophysics Data System (ADS)

    Courtial, P.; Wilke, M.; Potuzak, M.; Dingwell, D. B.

    2005-12-01

    glasses from different temperatures, when possible, using wet-chemical analysis (i.e., K-dichromate potentiometry). Both datasets agree reasonably well (within 10 %). References: Wilke et al. (2004) Chemical Geology, 213, 71-87.

  3. Long-Term Exposure of Tropical Soils to Pressure Treated Lumber, Barro Colorado Island, Panama: Impacts on Soil Metal Mobility and Microbial Community Structure

    NASA Astrophysics Data System (ADS)

    Marietta, M. L.; Fowle, D. A.; Roberts, J. A.

    2008-12-01

    Pressure treated lumber (CCA) has been used in a variety of structures for over seven decades, but recent concerns have been raised about leaching of metals such as chromium (Cr) and arsenic (As) into proximal soils and water supplies. Pressure treated lumber abundance and its continued use necessitate a thorough understanding of metal release and sequestration in the subsurface. To date, no long-term, in situ study on the migration of CCA compounds from lumber has been performed. Barro Colorado Island, Panama is the site of several previous CCA studies and provides an opportunity to investigate the long-term (>70 years) effects of pressure treated lumber in oxisols, where high rainfall and warm temperatures may represent an end-member condition for the leaching and mobility of these metals. Soil samples from CCA and control sites were measured for Cr, As, Cu, Zn, and Fe abundances, microbial biomass and community structure via phospholipid fatty acid analysis, along with basic soil properties. CCA lumber samples were also characterized for their metal abundance. Lumber treated with zinc meta-arsenite displayed advanced decay with elevated As, Cu, and Zn concentrations observed in the adjacent soil. Increased soil organic matter and microbial biomass correlate to decreases in Fe and Fe-associated metals compared to the control. High As concentrations persist to <1 m of the source. Lumber treated with potassium dichromate contained high chromium concentrations and displayed little decay, however, soil concentrations of Cr, Fe, and Cu were generally less than control soils. Over these same intervals, soil organic matter and microbial biomass increased, particularly the fraction of metal reducing bacteria (MRB). We hypothesize that organic carbon loading from lumber stimulates MRB, leading to mobilization of Fe and Fe-associated metals from these oxide-rich soils. Principal component analysis of PLFA data confirms a distinction between controls and samples with

  4. Ecotoxicological risks associated with tannery effluent wastewater.

    PubMed

    Shakir, Lubna; Ejaz, Sohail; Ashraf, Muhammad; Qureshi, Naureen Aziz; Anjum, Aftab Ahmad; Iltaf, Imran; Javeed, Aqeel

    2012-09-01

    The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P<0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural

  5. Treatability study Number PDC-1-O-T. Final report

    SciTech Connect

    1998-04-22

    Los Alamos National Laboratory provided treatability study samples from four waste streams, designated Stream {number_sign}1, Stream {number_sign}3, Stream {number_sign}6, and Stream {number_sign}7. Stream {number_sign}1 consisted of one 55-gallon drum of personal protective equipment (PPE), rags, and neutralizing agent (bicarbonate) generated during the cleanup of a sodium dichromate solution spill. Stream {number_sign}3 was one 55-gallon drum of paper, rags, lab utensils, tools, and tape from the decontamination of a glovebox. The sample of Stream {number_sign}6 was packaged in three 30-gallon drums and a 100 ft{sup 3} wooden box. It consisted of plastic sheeting, PPE, and paper generated from the cleanup of mock explosive (barium nitrate) from depleted uranium parts. Stream {number_sign}7 was scrap metal (copper, stainless and carbon steel joined with silver solder) from the disassembly of gas manifolds. The objective of the treatability study is to determine: (1) whether the Perma-Fix stabilization/solidification process can treat the waste sample to meet Land Disposal Restrictions and the Waste Acceptance Criteria for LANL Technical Area 54, Area G, and (2) optimum loading and resulting weight and volume of finished waste form. The stabilized waste was mixed into grout that had been poured into a lined drum. After each original container of waste was processed, the liner was closed and a new liner was placed in the same drum on top of the previous closed liner. This allowed an overall reduction in waste volume but kept waste segregated to minimize the amount of rework in case analytical results indicated any batch did not meet treatment standards. Samples of treated waste from each waste stream were analyzed by Perma-Fix Analytical Services to get a preliminary approximation of TCLP metals. Splits of these samples were sent to American Environmental Network`s mixed waste analytical lab in Cary, NC for confirmation analysis. Results were all below applicable

  6. Deferoxamine pretreatment prevents Cr(VI)-induced nephrotoxicity and oxidant stress: role of Cr(VI) chelation.

    PubMed

    Molina-Jijón, Eduardo; Zarco-Márquez, Guillermo; Medina-Campos, Omar Noel; Zataraín-Barrón, Zyanya Lucía; Hernández-Pando, Rogelio; Pinzón, Enrique; Zavaleta, Rosa Marina; Tapia, Edilia; Pedraza-Chaverri, José

    2012-01-27

    Deferoxamine (DFO) is a recognized iron chelator which has been shown to exert nephroprotection in models of toxic nephropathies. In the present work the potential protective effects of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress were evaluated. Rats were injected with a single injection (15mg/kg, s.c.) of potassium dichromate (K(2)Cr(2)O(7)). DFO was given as a single i.p. injection 30min before K(2)Cr(2)O(7) administration at three different doses (100, 200 and 400mg/kg). It was found that DFO pretreatment attenuated, in a dose-dependent way, K(2)Cr(2)O(7)-induced renal dysfunction and structural alterations evaluated by serum creatinine, blood urea nitrogen, creatinine clearance, proteinuria, plasma glutathione peroxidase activity, urinary excretion of N-acetyl-β-d-glucosaminidase and histological analyses. Furthermore, DFO prevented the K(2)Cr(2)O(7)-induced renal oxidant stress and the decrease in the activity of the antioxidant enzymes superoxide dismutase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase and catalase. Finally it was found that DFO, at 400mg/kg, decreases renal Cr(VI) content which prompted us to evaluate the potential Cr(VI) chelating properties of this compound. Indeed was found in an in vitro assay that DFO was an effective Cr(VI) chelator with an IC(50) of 800μg. In additional groups of rats was found that DFO posttreatment was ineffective to attenuate K(2)Cr(2)O(7)-induced nephrotoxicity and renal oxidant stress. Furthermore, DFO was unable to modify urinary excretion of total chromium. The nephroprotective effect of DFO against Cr(VI)-induced nephrotoxicity and oxidant stress may be explained, at least partially, by the ability of DFO to chelate Cr(VI) and to attenuate renal Cr(VI) content. However, it cannot be excluded that the ability of DFO to chelate iron may also be involved in the protection observed in our study. PMID:22115772

  7. Anthropogenic Charcoal Deposits: Analogues for the Long-Term Functioning and Stability of Biochar in European Soils?

    NASA Astrophysics Data System (ADS)

    Mugford, Ian; Street-Perrot, Alayne; Santín, Cristina; Denman, Huw

    2014-05-01

    Anthropogenic charcoal deposits, characterised by thick charcoal-rich soil horizons, offer an invaluable Late Quaternary record of pyrogenic carbon (PyC) additions to soils. A traditional source of archaeological, anthracological and palaeoecological data, the potential contribution of anthropogenic charcoal deposits to soil science and assessment of carbon (C) sequestration is often overlooked. If addition of biochar to soils is to form a key component of a low-C economy, crucial questions must be addressed relating to its longevity and behaviour in the soil environment. With rare exceptions, previous studies have focussed on short-term incubation experiments and field or pot trials, often neglecting important natural soil and environmental processes. This study addresses these issues by comparing the physicochemical properties of European anthropogenic charcoal-rich deposits, with 14C ages ranging from > 43 ka to Modern, to native soils (nearby control sites). We will present results from a study of 23 charcoal-rich soil cores, collected from a 'Pre-historic' ditch mound, a Bronze Age burnt mound, a Roman furnace, and post-mediaeval and Modern Meilers, situated along a climatic gradient from Mediterranean (Southern Italy) to Humid Temperate (South Wales). The ability of charcoal to alter fertility and retain plant-available nutrients was assessed by measuring soil cation- exchange capacity. Retention of refractory C by the charcoal deposits was evaluated from their total organic C (TOC) contents, atomic H:C and O:C ratios, and residues after acid- dichromate oxidation. Picked charcoal fragments were also compared with modern biochars and biomass using: 1) their thermogravimetric recalcitrance (R50) indices (Harvey et al. 2012); and 2) attenuated total reflectance (ATR) FT-IR data, to gauge the development of functional groups linked to the long-term oxidation of the particle surfaces. Radiocarbon dating was used to assess the ages of the deposits. Our study

  8. Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

    DOE PAGESBeta

    Singh, Rajesh; Dong, Hailiang; Liu, Deng; Zhao, Linduo; Marts, Amy R.; Farquhar, Erik; Tierney, David L.; Almquist, Catherine B.; Briggs, Brandon R.

    2014-10-22

    Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions bymore » this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to1.9 μM h₋1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature

  9. Aberration of mitosis by hexavalent chromium in some Fabaceae members is mediated by species-specific microtubule disruption.

    PubMed

    Eleftheriou, Eleftherios P; Michalopoulou, Vasiliki A; Adamakis, Ioannis-Dimosthenis S

    2015-05-01

    Because the detrimental effects of chromium (Cr) to higher plants have been poorly investigated, the present study was undertaken to verify the toxic attributes of hexavalent chromium [Cr(VI)] to plant mitotic microtubules (MTs), to determine any differential disruption of MTs during mitosis of taxonomically related species and to clarify the relationship between the visualized chromosomal aberrations and the Cr(VI)-induced MT disturbance. For this purpose, 5-day-old uniform seedlings of Vicia faba, Pisum sativum, Vigna sinensis and Vigna angularis, all belonging to the Fabaceae family, were exposed to 250 μM Cr(VI) supplied as potassium dichromate (K₂Cr₂O₇) for 24, 72 and 120 h and others in distilled water serving as controls. Root tip samples were processed for tubulin immunolabelling (for MT visualization) and DNA fluorescent staining (for chromosomal visualization). Microscopic preparations of cell squashes were then examined and photographed by confocal laser scanning microscopy (CLSM). Cr(VI) halted seedling growth turning roots brown and necrotic. Severe chromosomal abnormalities and differential disturbance of the corresponding MT arrays were found in all mitotic phases. In particular, in V. faba MTs were primarily depolymerized and replaced by atypical tubulin conformations, whereas in P. sativum, V. sinensis and V. angularis they became bundled in a time-dependent manner. In P. sativum, the effects were milder compared to those of the other species, but in all cases MT disturbance adversely affected the proper aggregation of chromosomes on the metaphase plate, their segregation at anaphase and organization of the new nuclei at telophase. Cr(VI) is very toxic to seedling growth. The particular effect depends on the exact stage the cell is found at the time of Cr(VI) entrance and is species-specific. Mitotic MT arrays are differentially deranged by Cr(VI) in the different species examined, even if they are taxonomically related, while their

  10. Distinct Contributions of JNK and p38 to Chromium Cytotoxicity and Inhibition of Murine Embryonic Stem Cell Differentiation

    PubMed Central

    Chen, Liang; Ovesen, Jerald L.; Puga, Alvaro; Xia, Ying

    2009-01-01

    Background Potassium dichromate [Cr(VI)] is a widespread environmental toxicant responsible for increased risk of several human diseases. Cr(VI) exposure leads to activation of mitogen-activated protein kinases (MAPKs), including c-Jun N-terminal kinase (JNK)1/2, p38, and extracellular-signal regulated kinase (ERK)1/2. Objectives We evaluated the contribution of MAPKs to Cr(VI) toxicity. Methods Phosphorylation of MAPKs and their downstream effectors was evaluated by Western immunoblotting; reactive oxygen species were measured by DCFDA (5′,6′-chloromethyl-2′-7′-dichlorofluorescin diacetate) labeling and flow cytometry, and glutathione and glutathione disulfide levels were determined by monochrome graphic spectroflurometer. Cytotoxicity was assessed by the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay and colony formation. Embryoid body (EB) differentiation was evaluated by contracting cardiomyocyte formation, and real-time polymerase chain reaction (RT-PCR) was used for cardiomyocyte-specific and stem-cell-specific gene expression. Results Acute treatment of mouse embryonic stem (ES) cells with 50 μM Cr(VI) induced the rapid phosphorylation of JNK, p38, and ERK and their respective downstream transcription factors, c-JUN, activating transcription factor-2, and ELK1. MAPK activation and cytotoxicity induction were partially blocked by pretreatment with the antioxidant N-acetyl cysteine. Ablation of the upstream MAP kinase kinase (MAP2K7) in ES cells prevented JNK activation, whereas ablation of MAP2K4 prevented both JNK and p38 activation. Using specific MAPK inhibitors and MAP2K4- and MAP2K7-deficient ES cells, we showed that JNK reduced acute Cr(VI) cytotoxicity, p38 potentiated it, and ERK had no effect. At low submicromolar concentrations, Cr(VI) caused MAP2K4/7-dependent JNK activation and MAP2K4-dependent p38 activation and strongly inhibited contracting cardiomyocyte development in wild-type ES

  11. BICAPA case study of natural hazards that trigger technological disasters

    NASA Astrophysics Data System (ADS)

    Boca, Gabriela; Ozunu, Alexandru; Nicolae Vlad, Serban

    2010-05-01

    Industrial facilities are vulnerable to natural disasters. Natural disasters and technological accidents are not always singular or isolated events. The example in this paper show that they can occur in complex combinations and/or in rapid succession, known as NaTech disasters, thereby triggering multiple impacts. This analysis indicates that NaTech disasters have the potential to trigger hazmat releases and other types of technological accidents. Climate changes play an important role in prevalence and NATECH triggering mechanisms. Projections under the IPCC IS92 a scenario (similar to SRES A1B; IPCC, 1992) and two GCMs indicate that the risk of floods increases in central and eastern Europe. Increase in intense short-duration precipitation is likely to lead to increased risk of flash floods. (Lehner et al., 2006). It is emergent to develop tools for the assessment of risks due to NATECH events in the industrial processes, in a framework starting with the characterization of frequency and severity of natural disasters and continuing with complex analysis of industrial processes, to risk assessment and residual functionality analysis. The Ponds with dangerous technological residues are the most vulnerable targets of natural hazards. Technological accidents such as those in Baia Mare, (from January to March 2000) had an important international echo. Extreme weather phenomena, like those in the winter of 2000 in Baia Mare, and other natural disasters such as floods or earthquakes, can cause a similar disaster at Târnăveni in Transylvania Depression. During 1972 - 1978 three decanting ponds were built on the Chemical Platform Târnăveni, now SC BICAPA SA, for disposal of the hazardous-wastes resulting from the manufacture of sodium dichromate, inorganic salts, sludge from waste water purification and filtration, wet gas production from carbide. The ponds are located on the right bank of the river Târnava at about 35-50m from the flooding defense dam. The total

  12. Prospective role of ascorbic acid (vitamin C) in attenuating hexavalent chromium-induced functional and cellular damage in rat thyroid.

    PubMed

    Qureshi, Irfan Zia; Mahmood, Tariq

    2010-07-01

    Occupational exposure to toxic heavy metals may render industrial workers with thyroid-related problems. Here, we examined the role of ascorbic acid (vitamin C) against hexavalent chromium Cr (VI)-induced damage in rat thyroid gland. Potassium dichromate (K2Cr2O7) and ascorbic acid doses were 60 microg and 120 mg kg(-1) body wt (intraperitoneally [i.p.]) respectively. Treatment regimens were group I rats, saline treated control; group II, only K2Cr2O7; group III, ascorbic acid 1 hour prior K2Cr2O7; group IV, simultaneous doses of ascorbic acid and K2Cr2O7, and group V, a combined premix dose of ascorbic acid and K2 Cr2O7 (2:1 ratio). Blood samples were taken before dosing the animals and 48 hours post exposure to determine the serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) concentrations. Toward end of experiment, rats were sacrificed and thyroid glands were processed to evaluate the extent of cellular insult. Results showed significantly increased TSH and decreased FT3 and FT4 concentrations in groups II, III and IV rats as compared to control levels (p < 0.05). In contrast, in group V rats, serum TSH, FT3 and FT4 concentrations neared control concentrations. Histopathologically, protective effect of ascorbic acid was found in group V rats only, where thyroid gland structure neared control thyroid except the follicular size that was decreased (p < 0.05). Follicular density was no different from control. Basal laminae were intact, interfollicular spaces were normal. Colloid retraction and/or reabsorption were reduced maximally. Epithelial cell height was no different from control; epithelial follicular index increased only 1.3 fold, whereas nuclear-cytoplasmic (N/C) ratio was decreased by 14% only. The study indicates that the ascorbic acid may have the potential to protect thyroid gland from chromium toxicity; however, the study warrants further in-depth experimentation to precisely elucidate this role. PMID:20504825

  13. Renoprotective Effect of Lactoferrin against Chromium-Induced Acute Kidney Injury in Rats: Involvement of IL-18 and IGF-1 Inhibition

    PubMed Central

    Hegazy, Rehab; Salama, Abeer; Mansour, Dina; Hassan, Azza

    2016-01-01

    Hexavalent chromium (CrVI) is a heavy metal widely used in more than 50 industries. Nephrotoxicity is a major adverse effect of chromium poisoning. The present study investigated the potential renoprotective effect of lactoferrin (Lf) against potassium dichromate (PDC)-induced acute kidney injury (AKI) in rats. Beside, because previous studies suggest that interlukin-18 (IL-18) and insulin-like growth factor-1 (IGF-1) play important roles in promoting kidney damage, the present work aimed to evaluate the involvement of these two cytokines in PDC model of AKI and in the potential renoprotective effect of lactoferrin. Adult male albino Wistar rats were pretreated with Lf (200mg/kg/day, p.o.) or (300mg/kg/day, p.o.); the doses that are usually used in the experiment studies, for 14 days followed by a single dose of PDC (15mg/kg, s.c.). PDC caused significant increase in serum urea, creatinine, and total protein levels. This was accompanied with decreased renal glutathione content, and increased renal malondialdehyde, IL-18, IL-4, nuclear factor kappa B (NFκB), IGF-1, and the phosphorylated form of forkhead box protein O1 (FoxO1) levels. Moreover, normal expression IFN-γ mRNA and enhanced expression of TNF-α mRNA was demonstrated in renal tissues. Histopathological investigations provoked deleterious changes in the renal tissues. Tubular epithelial hyperplasia and apoptosis were demonstrated immunohistochemically by positive proliferating cell nuclear antigen (PCNA), Bax, and Caspase-3 expression, respectively. Pretreatment of rats with Lf in both doses significantly corrected all previously mentioned PDC-induced changes with no significant difference between both doses. In conclusion, the findings of the present study demonstrated the involvement of oxidative stress, inflammatory reactions, tubular hyperplasia and apoptosis in PDC-induced AKI. It suggested a role of IL-18 through stimulation of IL-4-induced inflammatory pathway, and IGF-1 through triggering FoxO1

  14. Mechanical behavior and structure of passive films on austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Al-Amr, Abdulaziz

    2005-07-01

    The Taguchi analysis method was used in conjunction with ex-situ and in-situ nanoindentation tests to study the effects of alloy chemistry, solution pH, and halide ion concentrations on the mechanical fracture of electrochemically grown passive films formed at passive and metastable pitting potentials. Three austenitic stainless steels, SS, 304, 316, and 904L were anodically polarized in hydrochloric acid solutions for this study. The ex-situ study indicated that the alloy chemistry is the dominant factor of the mechanical fracture of the film formed at a stable passive potential; the average load to fracture the films using a 450 nm radius diamond tip was 52 muN. The films formed on 904L were the strongest, while the films on 316 SS were the weakest. The fracture load of the films formed at a metastable pitting potential, on the other hand, was equally influenced by the chloride ion concentration and the alloy chemistry. The load at fracture of films formed in the metastable pitting region was 64% of the fracture load of passive films formed at a stable potential. The fracture load of the passive films was depended on the degree of crystallinity of the passive film. The passive film on 316SS with lower density of crystalline islands than that of 304 SS had the lowest fracture load. In contrast, when the film was epitaxial, the fracture load was the largest. The dichromate treatment results indicate that the increase in degree of crystallinity of the passive films is associated with the increase in the chromium content of the substrate. In-situ measurements during anodic polarization led to similar behavior and results. The measured strength of films measured in ambient conditions after removal from the electrolyte was greater than when the films were measured in situ. However, the trends in film strength as a function of environment are the same between in situ and ex situ testing, suggesting the two tests are both feasible methods of analyzing environmental

  15. Cytotoxic and clastogenic effects of soluble and insoluble compounds containing hexavalent and trivalent chromium.

    PubMed Central

    Levis, A. G.; Majone, F.

    1981-01-01

    Cr(III) and Cr(VI) compounds of varying solubilities have been tested in vitro for their ability to inhibit cell growth and nucleic acid and protein syntheses in BHK cells, to induce alterations in the mitotic cycle in HEp cells, and to increase the frequency of chromosomal aberrations and sister chromatid exchanges (SCE) in CHO cells. All Cr(VI) compounds, and particularly those containing soluble Cr(VI), such as potassium dichromate and zinc yellow, differentially inhibit macromolecular syntheses in BKH cells, that of DNA being always the most affected. Among Cr(III) compounds, which generally have very low cytotoxicity, chromite is particularly active, and inhibits cell growth and DNA synthesis even more than the poorly soluble Cr(VI) compounds. Preincubation in growth medium, with or without metabolizing cell cultures, solubilizes considerable amounts of Cr(VI) from zinc yellow and chromite, but significant amounts are also obtained from the most insoluble Cr(VI) pigments. When BHK cells are treated with such preincubated solutions, reduction of soluble Cr(VI) to Cr(III) by cell metabolites is seen with all Cr(VI) compounds, accompanied by decreased cytotoxicity. The same differences between Cr(VI) and Cr(III) compounds apply to the cytotoxic effects on mitosis of HEp cells and the clastogenic effects on CHO cells. The activity of chromite, the only Cr(III) pigment capable of significantly increasing the frequency of SCE, is due to contamination with soluble Cr(VI). In contrast to the very low cytotoxicity of Cr(III), much higher chromium levels are detected in the cells incubated with soluble Cr(III) than with the same concentrations of soluble Cr(VI). 50% and 75% of chromium accumulated in the cells during treatments with Cr(VI) and Cr(III) respectively remains firmly bound to the cells, even when they are incubated for up to 48 h in normal growth medium. Chromium accumulated in the cells after treatment with Cr(III) is most probably bound to the cell

  16. Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

    PubMed Central

    Singh, Rajesh; Dong, Hailiang; Liu, Deng; Zhao, Linduo; Marts, Amy R.; Farquhar, Erik; Tierney, David L.; Almquist, Catherine B.; Briggs, Brandon R.

    2015-01-01

    Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to1.9 µM h−1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature

  17. Stability of elemental carbon in a savanna soil

    NASA Astrophysics Data System (ADS)

    Bird, M. I.; Moyo, C.; Veenendaal, E. M.; Lloyd, J.; Frost, P.

    1999-12-01

    We have investigated the stability of oxidation-resistant elemental carbon (OREC) in a sandy savanna soil at the Matopos fire trial site, Zimbabwe. The protection of some soil plots from fire for the last 50 years at this site has enabled a comparison of OREC abundances between those plots which have been protected from fire and plots which have continued to be burnt. The total 0-5 cm OREC inventory of the soil protected from fire is estimated to be 2.0±0.5 mg cm-2; approximately half the "natural" OREC inventory at the study site of 3.8±0.5 mg cm-2 (the mean for plots burnt every 1-5 years). The associated half-life for natural OREC loss from the 0-5 cm interval of the protected plots is calculated to be <100 years, with the half-life for large carbonized particles (>2000 μm) in the soil being considerably <50 years. These results suggest that at least in well-aerated tropical soil environments, charcoal and OREC can be can be significantly degraded on decadal to centennial timescales. OREC abundance and carbon-isotope data suggest that OREC in coarse particles is progressively degraded into finer particle sizes, with a concomitant increase in resistance to oxidative degradation of OREC in the finer particle sizes due to the progressive loss of more readily degraded OREC. It remains unclear whether the OREC that is degraded is oxidized completely to CO2 and subsequently emitted from the soil, reduced to a sufficiently small particle size to be illuviated to deeper parts of the soil profile, solubilized and lost from the profile as dissolved organic carbon or transmuted into a chemical form which is susceptible to attack by the acid-dichromate reagent. The conclusion that a significant proportion of OREC can undergo natural degradation in well-aerated environments on decadal/centennial timescales suggests that only a fraction of the total production of OREC from biomass burning and fossil fuel combustion is likely to be sequestered in the slow

  18. Novel Fabrication Strategies for Multifunctional Hydrogel Particles

    NASA Astrophysics Data System (ADS)

    Lewis, Chrisitna L.

    2011-12-01

    Three fabrication strategies for poly (ethylene glycol) (PEG) -based microparticles and their utility for exploiting the advantages of viral nanotemplates and DNA oligonucleotides are presented in this dissertation: 1. Nucleic Acid Hybridization Assembly of Viral Nanotemplates on Microparticles A flow lithography technique known as stop-flow lithography (SFL) was used to fabricate microparticles with discrete regions for sample identification and patterned assembly of functionalized tobacco mosaic virus (TMV) nanotemplates. TMV nanotemplates were programmed with linker DNA, complementary to the probe DNA in the assembly region of the microparticles. The hybridization-based assembly yielded specific, programmable, and spatially selective assembly of TMV nanotemplates on encoded hydrogel microparticles and demonstrates a novel high throughput route to create multiplexed and multifunctional viral-synthetic hybrid microentities. 2. Microparticles Containing Functionalized Viral Nanotemplates Functionalized viral assemblies were uniformly distributed throughout hydrogel microparticles by direct embedding with a microfluidic flow-focusing device and UV photopolymerization. Fluorescence and confocal microscopy images showed uniform distribution of the TMV nanotemplates. Microparticles containing TMV-templated palladium (Pd) nanoparticles exhibited catalytic activity for the dichromate reduction reaction. The results reveal that microparticles provide a stable and simple-to-handle carrier for TMV nanotemplates and address a critical challenge of 3D assembly of functionalized viral hybrid nanomaterials. 3. DNA-Conjugated Microparticles via Replica Molding (RM) DNA-conjugated microparticles were fabricated using a soft-lithographic batch processing-based technique, known as RM. A humidity controlled environment was found to minimize the negative effects of rapid evaporation and ensure uniformity across batch fabricated microparticles. It was also found that PEG

  19. Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site - Part 2

    SciTech Connect

    Qafoku, Nikolla; Dresel, P. Evan; McKinley, James P.; Ilton, Eugene S.; Um, Wooyong; Resch, Charles T.; Kukkadapu, Ravi K.; Petersen, Scott W.

    2011-01-04

    At the Hanford Site, chromate was used throughout the 100 Areas (100-B, 100-C, 100-D/DR, 100-F, 100-H, and 100 K) as a corrosion inhibitor in reactor cooling water. Chromate was delivered in rail cars, tanker trucks, barrels, and local pipelines as dichromate granular solid or stock solution. In many occasions, chromate was inevitably discharged to surface or near-surface ground through spills during handling, pipeline leaks, or during disposal to cribs. The composition of the liquids that were discharged is not known and it is quite possible that Cr(VI) fate and transport in the contaminated sediments would be a function of the chemical composition of the waste fluids. The major objectives of this investigation which was limited in scope by the financial resources available, were to 1) determine the leaching characteristics of hexavalent chromium [Cr(VI)] from contaminated sediments collected from 100-D Area spill sites; 2) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford Site 100 Areas through the use of macroscopic leaching studies, and microscale characterization of contaminated sediments; and 3) provide information to construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 Area vadose zone that can be used for developing options for environmental remediation. The information gathered from this research effort will help to further improve our understanding of Cr(VI) behavior in the vadose zone and will also help in accelerating the 100 Area Columbia River Corridor cleanup by providing valuable information to develop remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry. A series of column experiments were conducted with contaminated sediments to study Cr(VI) desorption patterns. Column experiments used the field size fraction of the sediment samples and a simulated Hanford Site groundwater solution. Periodic stop flow events were applied to

  20. Comparative toxicogenomic analysis of oral Cr(VI) exposure effects in rat and mouse small intestinal epithelia

    SciTech Connect

    Kopec, Anna K.; Thompson, Chad M.; Kim, Suntae; Forgacs, Agnes L.; Zacharewski, Timothy R.

    2012-07-15

    Continuous exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water results in intestinal tumors in mice but not rats. Concentration-dependent gene expression effects were evaluated in female F344 rat duodenal and jejunal epithelia following 7 and 90 days of exposure to 0.3–520 mg/L (as sodium dichromate dihydrate, SDD) in drinking water. Whole-genome microarrays identified 3269 and 1815 duodenal, and 4557 and 1534 jejunal differentially expressed genes at 8 and 91 days, respectively, with significant overlaps between the intestinal segments. Functional annotation identified gene expression changes associated with oxidative stress, cell cycle, cell death, and immune response that were consistent with reported changes in redox status and histopathology. Comparative analysis with B6C3F1 mouse data from a similarly designed study identified 2790 differentially expressed rat orthologs in the duodenum compared to 5013 mouse orthologs at day 8, and only 1504 rat and 3484 mouse orthologs at day 91. Automated dose–response modeling resulted in similar median EC{sub 50}s in the rodent duodenal and jejunal mucosae. Comparative examination of differentially expressed genes also identified divergently regulated orthologs. Comparable numbers of differentially expressed genes were observed at equivalent Cr concentrations (μg Cr/g duodenum). However, mice accumulated higher Cr levels than rats at ≥ 170 mg/L SDD, resulting in a ∼ 2-fold increase in the number of differentially expressed genes. These qualitative and quantitative differences in differential gene expression, which correlate with differences in tissue dose, likely contribute to the disparate intestinal tumor outcomes. -- Highlights: ► Cr(VI) elicits dose-dependent changes in gene expression in rat intestine. ► Cr(VI) elicits less differential gene expression in rats compared to mice. ► Cr(VI) gene expression can be phenotypically anchored to intestinal changes. ► Species

  1. ANC, BNC and mobilization of Cr from polluted sediments in function of pH changes

    NASA Astrophysics Data System (ADS)

    Shtiza, A.; Swennen, R.; Cappuyns, V.; Tashko, A.

    2009-02-01

    responsible for the fast release of the Cr(VI) are: the chromate salts (i.e. sodium chromate and sodium dichromate), while sparingly soluble chromatite (CaCrO4) and hashemite (BaCrO4) release Cr(VI) very slowly. Thus, pH and mineral solubility have been identified as key factors in the retention and the release of the hexavalent CrO4 2- and Cr2O7 - from the COPR-rich pond sediments.

  2. Biological Parameters for Evaluating the Toxic Potency of Petroleum Ether Extract of Wattakaka volubilis in Wistar Female Rats

    PubMed Central

    Gopal, Velmani; Agrawal, Nitin; Mandal, Subhash C.

    2014-01-01

    Objectives: The present study investigated the toxic properties of petroleum ether extract of Wattakaka (W.) volubilis in Wistar female rats. Methods: An in vitro brine shrimp lethality bioassay was studied in A. Salina nauplii, and the lethality concentrations were assessed for petroleum ether extract of W. volubilis. A water soluble portion of the test extract was used in different concentrations from 100-1000 μg/mL of 1 mg/mL stock solution. A 24-hours incubation with a 1-mL aliquot in 50 mL of aerated sea water was considered to calculate the percentage rate of dead nauplii with test extract administration against a potassium-dichromate positive control. The acute and the sub-acute toxicities of petroleum ether extract of W. volubilis were evaluated orally by using gavage in female Wistar rats. Food and water intake, body weight, general behavioral changes and mortality of animals were noted. Toxicity or death was evaluated following the administration of petroleum ether extract for 28 consecutive days in the female rats. Serum biochemical parameters, such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, total cholesterol, triglyceride, total protein, glucose, urea, creatinine, sodium, potassium and α-amylase levels, were measured in the toxicity evaluations. Pathological changes in isolated organs, such as the liver, kidneys, and pancreas, were also examined using hematoxylin and eosin dye fixation after the end of the test extract’s administration. Results: The results of the brine-shrimp assay indicate that the evaluated concentrations of petroleum ether extract of W. volubilis were found to be non-toxic. In the acute and the sub-acute toxicity evaluations, no significant differences were observed between the control animals and the animals treated with extract of W. volubilis. No abnormal histological changes were observed in any of the animal groups treated with petroleum ether extract of W. volubilis. Conclusion: These results

  3. Growth and Process-Induced Defects and Recombination Mechanisms in Aluminum Gallium Arsenide/gallium Arsenide and CADMIUM(1-X) Zinc(x) Tellurium/cadmium Sulfide Photovoltaic Device Structures

    NASA Astrophysics Data System (ADS)

    Ringel, Steven Adam

    The objective of this research was to provide guidelines to improve the performance of crystalline GaAs and polycrystallize CdTe and CdZnTe solar cells through an improved understanding of defects and recombination mechanisms within these structures. Three main issues were investigated: the role of bulk defects and interface recombination on GaAs cell performance and design; performance limiting defects in CdTe thin film cells; and processing of wide bandgap CdZnTe for use as the top cell of a two cell tandem arrangement. In the first part of the research an improved methodology to determine lifetime and recombination velocity within AlGaAs/GaAs heteroface cells was developed. The quantitative dependence of device performance on defect characteristics was demonstrated. A novel device structure was proposed which is shown to minimize the effects of defects while resulting in high efficiency. The second area of research investigated the effects of the commonly used but poorly understood CdCl_2 treatment on CdTe/CdS solar cells. The CdCl_2 treatment was found to improve cell performance via increased carrier collection from the bulk and across the interface, and by a change in the dominant current transport mechanism from interface-assisted tunneling to depletion region recombination. However, an E _{v} + 0.64 eV trap was detected in the CdCl_2-treated cells, resulting from the formation of cadmium vacancy-related defects during processing, that may limit CdTe cell performance. A preliminary correlation between the trap density and cell V_{oc} was established. In the third area, 1.7 eV bandgap CdZnTe was successfully grown on CdS substrates by molecular beam epitaxy. However, subsequent standard cell processing reduced photoresponse, decreased the CdZnTe bandgap, and caused high series resistance. The high series resistance resulted from the preferential oxidation of Zn during the anneal, which was removed by a dichromate etch. The reaction of Zn with CdCl_2 and

  4. Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

    SciTech Connect

    Singh, Rajesh; Dong, Hailiang; Liu, Deng; Zhao, Linduo; Marts, Amy R.; Farquhar, Erik; Tierney, David L.; Almquist, Catherine B.; Briggs, Brandon R.

    2014-10-22

    Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to1.9 μM h₋1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of

  5. Effect of various storage conditions on the stability of quinolones in raw milk.

    PubMed

    Chen, Meixia; Wen, Fang; Wang, Hui; Zheng, Nan; Wang, Jiaqi

    2016-07-01

    Research on the storage stability of antibiotic residues in milk is important for method development or validation, milk quality control and risk assessment during screening, confirmation, qualitative or quantitative analysis. This study was conducted using UPLC-MS/MS to determine the stability of six quinolones - ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), sarafloxacin (SAR), difloxacin (DIF) and flumequine (FLU) - in raw milk stored under various conditions to investigate if quinolones degrade during storage of milk, and finally to determine optimal storage conditions for analysis and scientific risk assessment of quinolone residues in raw milk. The storage conditions included different temperatures and durations (4°C for 4, 8, 24 and 48 h; -20°C for 1, 7 and 30 days; -80°C for 1, 7 and 30 days), thawing temperatures (25, 40 and 60°C), freeze-thaw cycles (1-5), and the addition of different preservatives (sodium thiocyanate, sodium azide, potassium dichromate, bronopol and methanal). Most quinolones exhibited high stability at 4°C for up to 24 h, but began to degrade after 48 h. In addition, no degradation of quinolones was seen when milk samples were stored at -20°C for up to 7 days; however, 30 days of storage at -20°C resulted in a small amount of degradation (about 30%). Similar results were seen when samples were stored at -80°C. Moreover, no losses were observed when frozen milk samples were thawed at 25, 40 or 60°C. All the quinolones of interest, except sarafloxacin, were stable when milk samples were thawed at 40°C once and three times, but unstable after five freeze-thaw cycles. Preservatives affected the stability of quinolones, but the effects differed depending on the preservative and quinolone. The results of this study indicate optimum storage protocols for milk samples, so that residue levels reflect those at the time of initial sample analysis, and should improve surveillance programmes for quinolones in raw milk

  6. 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. PMID:24209303

  7. Reduction of aqueous transition metal species on the surfaces of Fe(II)-containing oxides

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.

    1996-01-01

    Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1-7 at 25??C. For an aqueous transition metal m, such reactions are 3[Fe2+Fe3+2]O4(magnetite) + 2/nmz ??? 4[Fe3+2]O3(maghemite) + Fe2+ + 2/nmz-n and 3[Fe2+Ti]O3(ilmenite) + 2/nmz ??? Fe3+2Ti3O9(pseudorutile) + Fe2+ + 2/nmz-n, where z is the valance state and n is the charge transfer number. The half cell potential range for solid state oxidation [Fe(II)] ??? [Fe(III)] is -0.34 to -0.65 V, making structural Fe(II) a stronger reducing agent than aqueous Fe2+ (-0.77 V). Reduction rates for aqueous metal species are linear with time (up to 36 h), decrease with pH, and have rate constants between 0.1 and 3.3 ?? 10-10 mol m-2 s-1. Iron is released to solution both from the above reactions and from dissolution of the oxide surface. In the presence of chromate, Fe2+ is oxidized homogeneously in solution to Fe3+. X-ray photoelectron spectroscopy (XPS) denotes a Fe(III) oxide surface containing reduced Cr(III) and V(IV) species. Magnetite and ilmenite electrode potentials are insensitive to increases in divalent transition metals including Zn(II), Co(II), Mn(II), and Ni(II) and reduced V(IV) and Cr(III) but exhibit a log-linear concentration-potential response to Fe(III) and Cu(II). Complex positive electrode responses occur with increasing Cr(VI) and V(V) concentrations. Potential dynamic scans indicate that the high oxidation potential of dichromate is capable of suppressing the cathodic reductive dissolution of magnetite. Oxide electrode potentials are determined by the Fe(II)/Fe(III) composition of the oxide surface and respond to aqueous ion potentials which accelerate this oxidation process. Natural magnetite sands weathered under anoxic conditions are electrochemically reactive as demonstrated by rapid chromate reduction and the release of aqueous Fe(III) to experimental

  8. Molecular Marker Approach on Characterizing and Quantifying Charcoal in Environmental Media

    NASA Astrophysics Data System (ADS)

    Kuo, L.; Herbert, B. E.; Louchouarn, P.

    2006-12-01

    levoglucosan in the two charcoals. Interestingly, the low temperature charcoals are undetectable by the acid dichromate oxidation method, a popular soot/charcoal analytical approach. Our study demonstrates that levoglucosan can serve as a proxy of low temperature charcoals that are undetectable using other BC methods. Moreover, our study highlights the limitations of the common BC quantification methods to characterize the entire BC continuum.

  9. Embryonation ability of Ascaridia galli eggs isolated from worm uteri or host faeces.

    PubMed

    Rahimian, Shayan; Gauly, Matthias; Daş, Gürbüz

    2016-01-15

    Experimental infection models for Ascaridia galli rely on the use of eggs isolated either directly from worm uteri or from host faeces. We investigated whether A. galli eggs isolated from the two sources differ in their embryonation ability. A. galli eggs originating from 12 worm infrapopulations were isolated both from faeces of the living host (faecal eggs) and directly from worm uteri after host necropsy (uterine eggs). The isolated eggs from each infrapopulation and source were incubated in Petri dishes (n=24) containing a potassium-dichromate (0.1%) medium for 28 days (d) at room temperature. Starting from the day of egg isolation (d0), in ovo larval development was evaluated every second day by examining morphological characteristics of 200 eggs/petri dish. A total of 72,000 eggs were classified into undeveloped, early development, vermiform or fully embryonated stages. Isolation procedures caused similar damage to uterine and faecal eggs (2.2% and 0.5%, respectively; P=0.180). The first sign of in ovo embryonic development in faecal eggs (7%) was observed during the 24-h period when faeces were collected. On d28, a higher percentage of uterine eggs remained undeveloped when compared with faecal eggs (58.6% vs 11.0%; P<0.001). Although a higher (P<0.001) percentage of faecal eggs entered both the early developmental and vermiform stages, which took place primarily within the first two weeks of incubation, there was no time-shift between the development of faecal and uterine eggs. Starting from day 10, higher (P<0.05) percentages of faecal eggs completed embryonation compared with uterine equivalents. Eggs from both sources reached a plateau of embryonation by the end of 2nd week of incubation, with faecal eggs having a greater than two-fold higher embryonation ability. Cumulative mortality was higher in uterine eggs (14.3%) than in faecal eggs (0.2%). We conclude that faecal eggs have a higher embryonation ability than uterine eggs possibly due to maturation

  10. Hanford's 100-HX Pump and Treat Project - a Successful Blend of Science, Technology, Construction, and Project Management - 12412

    SciTech Connect

    Albin, Kenneth A.; Bachand, Marie T.; Biebesheimer, Fred H.; Neshem, Dean O.; Smoot, John L.

    2012-07-01

    CH2M Hill Plateau Remediation Company (CHPRC) recently completed construction and start-up of the $25 million 100-HX Groundwater Pump and Treat Project for the Department of Energy (DOE) at its Hanford Reservation site in Washington State. From the onset, the 100-HX Project Leadership Team was able to successfully blend the science and technology of a state-of-the-art groundwater pump and treat system with the principles, tools, and techniques of traditional industrial-type construction and project management. From the 1940's through most of the 1980's, the United States used the Hanford Site to produce nuclear material for national defense at reactor sites located along the Columbia River. While the reactors were operational, large volumes of river water were treated with sodium dichromate (to inhibit corrosion of the reactor piping) and used as a coolant for the reactors. After a single pass through the reactor and before being discharged back to the river, the coolant water was sent to unlined retention basins to cool and to allow the short-lived radioactive contaminants to decay. As a result of these operations, hexavalent chromium was introduced to the vadose zone, and ultimately into the groundwater aquifer and the adjacent Columbia River. In addition, numerous leaks and spills of concentrated sodium dichromate stock solution over the lifetime of reactor operations led to higher concentrations of chromate in the vadose zone and groundwater in localized areas. As a result, the 100 Area was included in the National Priorities List sites under the Comprehensive Environmental Response Compensation and Liability Act of 1980 (CERCLA). The mission of the 100-HX Project is to significantly reduce the concentration of hexavalent chromium in the groundwater by treating up to 3.8 billion gallons (14,300 mega-liters) of contaminated water over its first nine years of operations. In order to accomplish this mission, groundwater scientists and geologists using

  11. Soil water repellency patterns following long-term irrigation with waste water in a sandy calcareous soil, SE Spain

    NASA Astrophysics Data System (ADS)

    Mataix-Solera, J.; García-Irles, L.; Morugán, A.; Doerr, S. H.; García-Orenes, F.; Atanassova, I.; Navarro, M. A.; Ayguadé, H.

    2009-04-01

    One of the consequences of long-term irrigation with waste water can be the development of soil water repellency (WR). Its emergence can affect soil-water balance, irrigation efficiency and crop yield. Water repellency development has been suggested to be controlled by parameters such as organic matter quantity and type present in the waste water, soil properties (particularly the texture), and the overall time period of irrigation. Here we examine the effect of long-term (~20 years) irrigation with low quality waste-water on soil wettability under a Populus alba tree stand used as a "green filter". The plot exhibited considerable micro-topography (ridges and furrows) and consisted of sandy calcareous soil (Xerofluvent). Water repellency and organic carbon content (OC) were studied in 160 samples taken from the plot and from an adjacent area used as control (no irrigated). From the control area 40 samples were taken from the first 5 cm of mineral soil (C samples). From the irrigated plot a total of 120 samples were collected. To account for the micro-topography of the terrain, 40 samples each were taken from ridges (R samples; 0-5 cm depth), furrows (F samples; 0-5 cm depth), and from furrows at depth (FD samples, 5-10 cm depth). Soil WR was assessed in the laboratory for all air dry samples using the water drop penetration time test (WDPT Test). Samples with WDPT ? 5 seconds were classified as non-repellent. Organic carbon content (OC) was analyzed in all samples by potassium dichromate oxidation method. We also carried out a detailed chemical characterisation of the organic matter in two furrow samples that exhibited contrasting wettability, but no major difference in OC content (F10: WDPT 9960s, OC 6.7%; F31: WDPT 10s, OC 7.5%). Following accelerated solvent extraction with Dichloro-methane/MeOH (95:5), the extract was analysed by GC-MS. All samples from the control area (C) were wettable (mean WDPT=1s). In the irrigated plot, water repellency was present for 48

  12. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments

    NASA Astrophysics Data System (ADS)

    Holroyd, N. J. Henry; Scamans, G. M.

    2013-03-01

    Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack ("pop-in" vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies ( E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (<0.2 wt pct) are typically ranging from

  13. Nitrogen availability from residues-based biochar at two pyrolisis temperatures

    NASA Astrophysics Data System (ADS)

    Coscione, Aline Renee; Silveira Bibar, Maria Paula; de Andrade, Cristiano Alberto

    2014-05-01

    Biochar has been studied for several applications, such as soil quality improvement, heavy metals remediation and N2O mitigation. Considering the soil quality improvement aspect it is desirable to evaluate if the nitrogen content in biochar samples obtained from several residues used as the biomass sources could be available for plants. Samples of sewage sludge (SS), coffee grounds (CG), chicken manure (CM) and fungi mycelia (FM) were pyrolyzed at two temperatures, 400 and 700 oC (indicated by the number 4 and 7 in this abstract, respectively), in order to obtain the biochar samples. The Kjeldahl nitrogen of biochar was (% m/m): 3.0 (CM4, CG7, FM7 and CG4); 2.0 (CM7 e SS4); 3.4 (FM7); 1.4 (SS7), with organic carbon (potassium dichromate method) ranging from 2.0 to 3.0% for all but CG4 (6%). The C/N ratio of biochar samples was: 9 (CM4, SS4 and CG7); 11 (CM7); 15 (SS7); 7 (FM4 and FM7); 21 (CG4). The eight soil + biochar resulting mixtures, prepared using the equivalent to 60 t/ha of biochar (about 3% w/w), and one additional control treatment (no biochar added) were incubated for 90 days, with four replications of each treatment per time evaluated. Inorganic nitrogen and soil pH measurements were performed for all treatments at 0, 5, 15, 30, 60 and 90 days of incubation. Soil moisture was kept at 40% soil water holding capacity, by weighting, during the experiment. The data was submitted to ANOVA with Tukey's average comparison test (p < 0.05). No significative pH changes were observed during the incubation of biochar samples. At the initial incubation time (zero days) no statistical difference was observed among biochar sources or pyrolisis temperatures. After five days of incubation SS4 and CM4 showed significant inorganic nitrogen release compared to all other treatments, behavior repeated at all the following times evaluated. For CM7, FM4 and FM7 maximum nitrogen availability was observed after 15 days, while it occurred after 90 days for SS4. After 90 days

  14. Innovative Use of Cr(VI) Plume Depictions and Pump-and-Treat Capture Analysis to Estimate Risks of Contaminant Discharge to Surface Water at Hanford Reactor Areas

    SciTech Connect

    Miller, Chuck W.; Hanson, James P.; Ivarson, Kristine A.; Tonkin, M.

    2015-01-14

    The Hanford Site nuclear reactor operations required large quantities of high-quality cooling water, which was treated with chemicals including sodium dichromate dihydrate for corrosion control. Cooling water leakage, as well as intentional discharge of cooling water to ground during upset conditions, produced extensive groundwater recharge mounds consisting largely of contaminated cooling water and resulted in wide distribution of hexavalent chromium (Cr[VI]) contamination in the unconfined aquifer. The 2013 Cr(VI) groundwater plumes in the 100 Areas cover approximately 6 km2 (1500 acres), primarily in the 100-HR-3 and 100-KR-4 groundwater operable units (OUs). The Columbia River is a groundwater discharge boundary; where the plumes are adjacent to the Columbia River there remains a potential to discharge Cr(VI) to the river at concentrations above water quality criteria. The pump-and-treat systems along the River Corridor are operating with two main goals: 1) protection of the Columbia River, and 2) recovery of contaminant mass. An evaluation of the effectiveness of the pump-and-treat systems was needed to determine if the Columbia River was protected from contamination, and also to determine where additional system modifications may be needed. In response to this need, a technique for assessing the river protection was developed which takes into consideration seasonal migration of the plume and hydraulic performance of the operating well fields. Groundwater contaminant plume maps are generated across the Hanford Site on an annual basis. The assessment technique overlays the annual plume and the capture efficiency maps for the various pump and treat systems. The river protection analysis technique was prepared for use at the Hanford site and is described in detail in M.J. Tonkin, 2013. Interpolated capture frequency maps, based on mapping dynamic water level observed in observation wells and derived water levels in the vicinity of extraction and injection wells

  15. Is There Evidence for Impact-Triggered Fires at the End Pleistocene?

    NASA Astrophysics Data System (ADS)

    Wolbach, W. S.; Stich, A.; Kloosterman, J. B.; Becker, L.; Kennett, J.; Firestone, R.; West, A.

    2007-05-01

    Recent evidence suggests an extraterrestrial contribution to the End Pleistocene extinctions. Sediments at the base of a carbon-rich, dark layer dating to ~12.9 ka contain magnetic grains, microspherules, elevated Ir, fullerenes with abundant 3He, and other evidence consistent with extraterrestrial impact [1]. To test the possibility that combustion of the impactor, carbon-bearing rocks, or biomass could have been triggered by the impact (as hypothesized at the End Cretaceous 65 Ma ago [2]), we searched for soot in a variety of Clovis-age sites marked by this dark layer in North America, Germany, and Belgium. Thirty-eight samples from the following North American sites were studied: Carolina Bays at Blackville and Myrtle Beach, SC; Murray Springs, AZ; Chobot Site, Alberta, Canada; Blackwater Draw, Clovis, NM; Glacial Lake Hind, Manitoba, Canada; Daisy Cave, San Miguel Channel Island, Santa Barbara. Four samples from the Usselo Horizon in Schleswig-Holstein and one sample from Lommel, Belgium were also analyzed. Dissolution and analysis procedures were based on those used successfully for detecting soot from impact- produced wildfires at the Cretaceous-Tertiary (K/T) boundary [3, 4, 5]. Reduced carbon was isolated from sediments using HCl and HCl/HF. Elemental carbon was separated from organic carbon by acidic dichromate oxidation. Any remaining minerals were removed from carbonaceous residues using sodium metatungstate density separation. The elemental carbon of interest (soot) was identified and characterized using SEM imaging and quantified by weighing and particle size analysis. Two of the samples contained significant quantities of soot: Murray Springs, AZ, with a soot content of 21 ± 5 ppm; and Carolina Bay, Blackville, SC, with a soot content of 1969 ± 167 ppm. None of the remaining End Pleistocene samples studied showed significant soot contents. Negative results do establish that surface contamination by soot was not a problem, even though some sample

  16. Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site

    SciTech Connect

    Dresel, P. Evan; Qafoku, Nikolla; McKinley, James P.; Fruchter, Jonathan S.; Ainsworth, Calvin C.; Liu, Chongxuan; Ilton, Eugene S.; Phillips, J. L.

    2008-07-16

    The major objectives of the proposed study were to: 1.) determine the leaching characteristics of hexavalent chromium [Cr(VI)] from contaminated sediments collected from 100 Area spill sites; 2.) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford Site 100 Areas through the use of i.) macroscopic leaching studies and ii.) microscale characterization of contaminated sediments; and 3.) provide information to construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 Area vadose zone. In addressing these objectives, additional benefits accrued were: (1) a fuller understanding of Cr(VI) entrained in the vadose zone that will that can be utilized in modeling potential Cr(VI) source terms, and (2) accelerating the Columbia River 100 Area corridor cleanup by providing valuable information to develop remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry. A series of macroscopic column experiments were conducted with contaminated and uncontaminated sediments to study Cr(VI) desorption patterns in aged and freshly contaminated sediments, evaluate the transport characteristics of dichromate liquid retrieved from old pipelines of the 100 Area; and estimate the effect of strongly reducing liquid on the reduction and transport of Cr(VI). Column experiments used the < 2 mm fraction of the sediment samples and simulated Hanford groundwater solution. Periodic stop-flow events were applied to evaluate the change in elemental concentration during time periods of no flow and greater fluid residence time. The results were fit using a two-site, one dimensional reactive transport model. Sediments were characterized for the spatial and mineralogical associations of the contamination using an array of microscale techniques such as XRD, SEM, EDS, XPS, XMP, and XANES. The following are important conclusions and implications. Results from column experiments indicated that most

  17. Multiplexed Volume Bragg Gratings in Narrowand Broad-band Spectral Systems: Analysis and Application

    NASA Astrophysics Data System (ADS)

    Ingersoll, Gregory B.

    Volume Bragg gratings (VBGs) are important holographic optical elements in many spectral systems. Using multiple volume gratings, whether multiplexed or arranged sequentially, provides advantages to many types of systems in overall efficiency, dispersion performance, flexibility of design, etc. However, the use of multiple gratings---particularly when the gratings are multiplexed in a single holographic optical element (HOE)---is subject to inter-grating coupling effects that ultimately limit system performance. Analyzing these coupling effects requires a more complex mathematical model than the straightforward analysis of a single volume grating. We present a matrix-based algorithm for determining diffraction efficiencies of significant coupled waves in these multiplexed grating holographic optical elements (HOEs). Several carefully constructed experiments with spectrally multiplexed gratings in dichromated gelatin verify our conclusions. Applications of this theory to broad- and narrow-band systems are explored in detailed simulations. Broadband systems include spectrum splitters for diverse-bandgap photovoltaic (PV) cells. Volume Bragg gratings can serve as effective spectrum splitters, but the inherent dispersion of a VBG can be detrimental given a broad-spectrum input. The performance of a holographic spectrum splitter element can be improved by utilizing multiple volume gratings, each operating in a slightly different spectral band. However, care must be taken to avoid inter-grating coupling effects that limit ultimate performance. We explore broadband multi-grating holographic optical elements (HOEs) in sandwiched arrangements where individual single-grating HOEs are placed in series, and in multiplexed arrangements where multiple gratings are recorded in a single HOE. Particle swarm optimization (PSO) is used to tailor these systems to the solar spectrum taking into account both efficiency and dispersion. Both multiplexed and sandwiched two-grating systems

  18. Dissolved Organic In Natural and Polluted Waters: Methodology and Results of Running Control of Chemical Oxygen Demand (cod) For The Inland and Marine Aquatic System

    NASA Astrophysics Data System (ADS)

    Melentyev, K. V.; Worontsov, A. M.

    Current control of dissolved organic matter in natural and waste waters is the definition traditionally of chemical oxygen demand (COD) -- one of the basic parameters of quality of water. According to the International Standard (ISO 6060), it requires not less than one hour, while in many cases the operative information about amount of dissolved organic matter in aquatic environments have importance for prevention of an emergency. The standard method is applicable to waters with meaning of COD above 30 mg O2/l and, as the chloride ion prevents, it could be difficult for assessment of organic matter in sea water. Besides it is based on dichromate oxidation of the sum of organic substances in strong acid conditions at the presence of silver and mercury, that resulted in formation toxic pollutants. Till now attempts of automation of the COD definition in aquatic system were limited, basically, to duplication of the technology submitted the above standard (automatic COD analyzers "SERES Co."-- France, or "Tsvet Co." - Russia). The system of ozone-chemiluminescence automatic control of organic matter in water (CS COD) is offered and designed. Its based on the ozone oxidation of these substances in flowing water system and measurement arising from luminescent effects. CS COD works in real time. An instrument uses for reaction the atmospheric air, doesn't require fill of reagents and doesn't make new toxic pollutants. The system was tested in laboratory, and biochemical control of organic matter in water samples gathered from the river Neva and other polluted inland water areas and basins in St. Petersburg region was fulfilled (distilled water was used as "zero" media). The results of systematization of these measurements are presented. The new special ozone generator and flowing reactor for real-time running control of different waters in natural conditions were developed, and several series of large - scale field experiments onboard research ship were provided

  19. Dissolved Organic In Natural and Polluted Waters: Methodology and Results of Running Control of Chemical Oxygen Demand (cod) For The Inland and Marine Aquatic System

    NASA Astrophysics Data System (ADS)

    Melentyev, K. V.; Worontsov, A. M.

    Current control of dissolved organic matter in natural and waste waters is the definition traditionally of chemical oxygen demand (COD) -- one of the basic parameters of quality of water. According to the International Standard (ISO 6060), it requires not less than one hour, while in many cases the operative information about amount of dissolved organic matter in aquatic environments have importance for prevention of an emergency. The standard method is applicable to waters with meaning of COD above 30 mg O2/l and, as the chloride ion prevents, it could be difficult for assessment of organic matter in sea water. Besides it is based on dichromate oxidation of the sum of organic substances in strong acid conditions at the presence of silver and mercury, that resulted in formation toxic pollutants. Till now attempts of automation of the COD definition in aquatic system were limited, basically, to duplication of the technology submitted the above standard (automatic COD analyzers "SERES Co."-- France, or "Tsvet Co." - Russia). The system of ozone-chemiluminescence automatic control of organic matter in water (CS COD) is offered and designed. Its based on the ozone oxidation of these substances in flowing water system and measurement arising from luminescent effects. CS COD works in real time. An instrument uses for reaction the atmospheric air, doesn't require fill of reagents and doesn't make new toxic pollutants. The system was tested in laboratory, and biochemical control of organic matter in water samples gathered from the river Neva and other polluted inland water areas and basins in St. Petersburg region was fulfilled (distilled water was used as "zero" media). The results of systematization of these measurements are presented. The new special ozone generator and flowing reactor for real-time running control of different waters in natural conditions were developed, and several series of large - scale field experiments onboard research ship were provided

  20. The effect of break of runoff connectivity on SOC concentration in loess catchment of the Lublin Upland (Poland)

    NASA Astrophysics Data System (ADS)

    Rejman, Jerzy; Rafalska-Przysucha, Anna; Paluszek, Jan

    2014-05-01

    Soil erosion processes lead to redistribution of soils and soil organic carbon (SOC) in the landscape. In this study, we aimed to evaluate the effect of runoff connectivity on horizontal and vertical SOC concentration in the catchment. SOC concentration was examined in a small agricultural catchment located in deep loess area of the Lublin Upland, Poland (51019'55"N, 22023'16"E). The catchment area of 5.6 ha is divided into 11 parcels. Conventional tillage is performed on each of the parcel and plow includes of 1-2 moldboard and 1 cultivator operations per year. Tillage is performed along the longest side of parcels. Crop rotation includes wheat, barley, sugar beets, potatoes and maize. Connectivity of temporal overland flow in the catchment is disturbed by grassed borders of the parcels. SOC concentration was studied in 151 sampling points in a grid 20 by 20 m. Structure of soil profile was studied in each of the sampling points, and soil cores were taken from two soil layers of 0-25 and 25-50 cm, and from 7 profiles located within the closed depression and the areas where line of temporary overland flow cross the grassed parcel borders. SOC concentration in soil samples was determined by wet combustion with dichromate solution. Depositional soils represented 57 profiles in the catchment. The thickness of accumulated soil layer varied from 20 to 151 cm with a mean of 55 cm. SOC concentration ranged from 8.4 to 15.0 g kg-1 (with a mean of 11.0 g kg-1) in the upper and from 2.9 to 14.5 g kg-1 (7.5) in the deeper soil layer. Coefficient of variation was 12.9% in the layer 0-25 cm, and 44.5% in the layer 25-50 cm. To find the reasons of high variability of SOC concentration in deeper soil layer, the location of depositional soils in the catchment was analyzed. The analysis enabled to distinguish two groups of depositional soils of different SOC concentration at the depth of 25-50 cm. Depositional soils located in the zones of temporal stagnation of overland flow (i