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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. Adsorption of dichromate ions on the red mud surface

    NASA Astrophysics Data System (ADS)

    Terekhova, M. V.; Gorichev, I. G.; Lainer, Yu. A.; Artamonova, I. V.; Rusakova, S. M.

    2014-07-01

    The possibility of using a red mud (waste of alumina production) as a sorbent of dichromate ions from aqueous solutions is studied. A method for the activation of red mud by hydrochloric acid is proposed. The dependences of the amount adsorbed of dichromate ions on the pH and initial concentration of aqueous solutions are studied.

  8. 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

  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, 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  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. Dichromated photosensitive materials: involvement of the polymeric matrix

    NASA Astrophysics Data System (ADS)

    Bolte, Michele; Israeli, Yael; Rivaton, Agnes; Frezet, Lawrence; Lessard, Roger A.

    2004-06-01

    Irradiation of dichromated polyvinyl alcohol and dichromated polyacrylic acid DC(PVA-PAA) at 365 nm was investigated in order to understand the involvement of the polymeric matrix in the reduction process of the Cr(VI) leading to the formation of the hologram. The photochemical evolution of the matrix was directly correlated to the disappearance of the absorbing species, chromium(VI). A special attention was paid to the absorption profile of the films. Due to the impermeability of the polymer, no oxidation proceeded. The reduction of Cr(VI) into Cr(V) induced the formation of carboxylate species perfectly correlated with the consumption of carboxylic groups. Besides the acido-basic reaction undergone by the carboxylic groups, the reduction of Cr(VI) provoked the cross-linking of the polymer. Each polymer appears to play a specific role in the mechanism.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. ARTICLES: Waveguide holograms in thin dichromated gelatin films

    NASA Astrophysics Data System (ADS)

    Bablumyan, A. S.; Balagurov, A. Ya; Morozov, V. N.; Shermergor, T. D.

    1984-05-01

    Thin dichromated gelatin films were used to record waveguide holograms directly inside the film. Information was stored and retrieved by light of the same wavelength. The waveguides were characterized by optical attenuation < 1 dB/cm and this value was retained after the film sensitization, exposure, and development cycle, so that holograms could be recorded. Sinusoidal gratings were formed and these were used to couple radiation into thin-film waveguides and also as waveguide Fourier holograms of two-dimensional images. The efficiency of a sinusoidal grating as a coupling component was 60%. A Fourier hologram reconstructed by the waveguide method with a diffraction efficiency of 11% was characterized by a recorded data density of ~ 105 bit/ mm2 over an area of 1 mm2.

  3. 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/.

  4. 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

  5. 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.

  6. Some new applications of ferroin as redox indicator in titrations with dichromate.

    PubMed

    Sriramam, K

    1972-11-01

    Working conditions for the titration of arsenic(III), hydroquinone, ferrocyanide, uranium(IV) and molybdenum(V) with dichromate in sulphuric acid and hydrochloric acid media have been established, with ferroin as the redox indicator.

  7. Dichromated Gelatine as a Material of Optical Element

    NASA Astrophysics Data System (ADS)

    Lee, Hyuk-Soo; Cho, Dong-Hyun; Choi, Yong-Jin; Son, Jung-Young; Park, Seung-Han

    1999-04-01

    In the fabrication process of optical elements (OEs) by the laser scanning method using a dichromated gelatin (DCG) photoplate, the expansion and drying stress of gelatine caused by inhomogeneous liquid flow inside the gelatine affects the shape of OEs. The reason this inhomogeneous liquid flow exists in the energy oversaturated parts of OEs is the presence of surplus energy. In order to obtain the OEs of desired spherical lens shape, the drying stress should be reduced and therefore the maximum energy of the illuminating laser should be defined not to cause the surplus energy. The maximum energy is investigated according to the relative concentrations of (NH4)2Cr2O7 to DCG. The use of photoplates with a relative concentration of (NH4)2Cr2O7 to gelatin of more than 20% has some advantages when making the lens raster, especially a short-focal-length lens raster. It is also very important to increase the drying time to reduce the total drying stress by maintaining high humidity during the drying process.

  8. 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…

  9. Solubility and metastable zone width of aqueous sodium dichromate dihydrate solutions in the presence of sodium chromate additive

    NASA Astrophysics Data System (ADS)

    Wang, Liping; Feng, Haitao; Dong, Yaping; Peng, Jiaoyu; Li, Wu

    2016-11-01

    Solubility and metastable zone width (MSZW) of aqueous sodium dichromate solutions in different concentration of sodium chromate were studied experimentally by the polythermal method using a turbidity monitoring technique. The effects of cooling rate R, saturation temperature T0 of sodium dichromate and concentration ci of sodium chromate on the MSZW were studied. The results show that the MSZW widens with increasing cooling rate R but it narrows with increasing saturation temperature T0 of sodium dichromate and concentration ci of sodium chromate. The experimental data were analyzed by using an equation, based on the classical three-dimensional nucleation theory, relating MSZW with cooling rate R.

  10. Genotoxic effects of linear alkyl benzene sulfonate, sodium pentachlorophenate and dichromate on Tetrahymena pyriformis.

    PubMed

    Wu, Y; Shen, Y

    1992-01-01

    DNA in macro- and micronuclei of Tetrahymena pyriformis treated with linear alkyl benzene sulfonate (LAS) and sodium pentachlorophenate (PCP-Na) were determined by microspectrophotometry. The effects on rate of formation of macronuclear DNA extrusion bodies were also studied. We found DNA content of micronuclei in 0.14 ppm LAS and 0.9 ppb PCP-Na was lower than in that of the control, and LAS was able to increase the formation rate of macronuclear DNA extrusion bodies (the formation rate was 54% in 11.3 ppm LAS and 25.6% in 16.7 ppm dichromate). We concluded that 0.14 ppm LAS (below the maximum acceptable toxicant concentration) was genotoxic, whereas 0.014 ppm LAS was not. Dichromate 0.05 ppm and 0.9 ppb PCP-Na, equal to and below the maximum acceptable toxicant concentration, respectively, were potentially genotoxic.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. Methylene Blue Dichromated-Gelatin Holograms: Antihumidity Method for Taking Off Strongly Adsorbing Humidity Groups

    NASA Astrophysics Data System (ADS)

    Wang, Ketai; Guo, Lurong; Zhu, Jianhua; Zhang, Weiping; Cheng, Bo

    1998-01-01

    A new, to our knowledge, method of modifying methylene blue dichromated-gelatin (MBDCG) holograms by use of ninhydrin and removal of their amino groups and carboxyl groups, which strongly adsorb humidity, has been developed. The modified MBDCG holograms are stable for 1000-line /mm gratings (diffractional efficiency of 95%) in a high-humidity environment (relative humidity of 80% -85%). The modifying reaction does not affect the diffraction efficiency of the MBDCG holograms. It is demonstrated that the amino groups and carboxyl groups of the side chains in the gelatin do not undergo the chelation reaction with Cr iii in the sensitive area.

  16. Spectropolarimetric investigation of the photoinduced dichroism and birefringence in malachite green/dichromated gelatin films

    NASA Astrophysics Data System (ADS)

    Markova, Bistra; Hristov, Boyan; Todorov, Todor; Nikolova, Ludmila; Stoilov, Georgi

    2009-06-01

    We report a spectropolarimetric investigation of the photoinduced anisotropy in dichromated gelatin films containing the dye malachite green. The investigation is done with a novel Spectral Stokesmeter which measures simultaneously and in real time (20 ms) the spectra of all the Stokes parameters of light in the spectral range 500-750 nm. This made it possible to measure not only the spectrum of the dichroism but also, for the first time to our knowledge, the spectrum of the photoinduced birefringence in these films. The results show that we can measure trustworthy dichroism larger than 0.02 and birefringence larger than 2 × 10-4.

  17. Behaviour of ferroin indicator in iron(ii)- dichromate titrations A Critical study.

    PubMed

    Sriramam, K

    1972-10-01

    A critical evaluation has been made of the optimum conditions for a successful direct and reverse titration of iron(II) with dichromate, with ferroin as indicator, taking into account the influence of acidity, the catalytic effect of iron(III) and the induction effect of the iron(II)-dichromate reaction on the indicator oxidation reaction. The difference in the behaviour of the indicator in the direct and reverse titrations is believed to be due to the presence of a slow : step in the indicator oxidation mechanism ; this is however surmounted in the reverse titration, making it possible to use the indicator even in a 2N sulphuric add medium for this titration. The higher potentials recorded in the reverse titration are believed to be due to the oxide film on the platinum metal electrode. While iron(III) seems to help lower the kinetic barrier of the slow step sufficiently in the indicator oxidation mechanism, the ferriin-ferroin system seems to help m a similar way toe establishment of a more positive potential of the Ct(VI)/Cr(III) system at the platinum electrode in me direct titration; this value explains the feasibility of the direct visual titration in 2N sulphuric acid, although the colour change at the end-point is slow for other reasons.

  18. Final report of CCQM-K96.1 `Determination of amount content of dichromate'

    NASA Astrophysics Data System (ADS)

    Hwang, Euijin; Lim, Youngran; Ma, Liandi; Wu, Bing

    2015-01-01

    The CCQM-K96.1 key comparison was a subsequent bilateral comparison to the CCQM-K96 'Determination of amount content of dichromate'. The comparisons were organized jointly by the inorganic analysis and electrochemical analysis working groups of the CCQM to test the abilities of the metrology institutes to measure the content amount of dichromate. The NIM China has obtained unsatisfactory results from the CCQM-K96. The NIM requested a bilateral comparison to demonstrate its capability after improvement. The KRISS acted as the coordinating laboratory and served as a link to the reference value of CCQM-K96. Both participants used high-accuracy constant current coulometry. A good agreement of the results was observed. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  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. Final report on key comparison CCQM-K96: Determination of amount content of dichromate

    NASA Astrophysics Data System (ADS)

    Máriássy, Michal; Hanková, Zuzana; Hwang, Euijin; Lim, Youngran; Pratt, Kenneth W.; Hioki, Akiharu; Asakai, Toshiaki; Bing, Wu; Liandi, Ma; Chao, Wei; Sobina, Alena; Shimolin, Alexandr; Junior, Wiler B. S.; Borges, Paulo P.; Matehuala, Francisco Javier; Segoviano, Francisco; Rivera, Griselda; Ramírez, Pedro; del Rocio Arvizu, María; Ortiz-Aparicio, José Luis

    2013-01-01

    The key comparison CCQM-K96 was organized jointly by the inorganic and electrochemistry working groups of CCQM to test the abilities of the metrology institutes to measure the amount content of dichromate. Slovak Institute of Metrology with help of KRISS acted as the coordinating laboratories. Eight NMIs took part in the comparison. All participants used high accuracy constant current coulometry. Good agreement of the results was observed. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. 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.

  2. Electrochemical titrations of thiosulfate, sulfite, dichromate and permanganate using dual microband electrodes.

    PubMed

    Rajantie, H; Williams, D E

    2001-01-01

    Applications of titration using dual gold microband electrodes in generator-collector mode are presented. The main advantage is that the method dispenses with the need for accurate volume measurements and reagent preparation: rather than balancing of molar amounts, the fluxes of analyte and titrant are balanced instead. The titrant is generated electrochemically and the end-point is detected amperometrically by the appearance of a current due to the presence of the titrant at the other band. The aim is to show the versatility and capability of the method that employs disposable mass-produced electrodes and uses pulsed motion of the electrode before a measurement to renew the boundary conditions. The titration of ascorbic acid (vitamin C) with ferricyanide, which has been a model system, was extended to the determination of thiosulfate and sulfite with iodine and the determination of dichromate and permanganate with iron(II). The accuracy, limited by the present fabrication reproducibility of the disposable electrodes, is +/- 10%. The results demonstrate that the method is effective even with a very simple set-up, and the actual time needed for common titrations is significantly decreased. These examples demonstrate a comprehensive basis for further development and applications, including standard titrations in industry.

  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. 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.

  5. 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

  6. 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.

  7. A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV).

    PubMed

    Rao, G G; Rao, P K

    1966-09-01

    Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator.

  8. 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.

  9. [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

  10. Evaluation of effects of melatonin and caffeic acid phenethyl ester on acute potassium dichromate toxicity and genotoxicity in rats

    PubMed Central

    Cengiz, Mujgan; Alansal, Nurnisa Oya; Tuncdemir, Matem; Tanriverdi, Gamze; Bayoglu, Burcu

    2016-01-01

    Objective: The aim of this study is to investigate the possible protective effects of melatonin and caffeic acid phenethyl ester (CAPE) on potassium dichromate (K2 Cr2O7)-induced nephrotoxicity and genotoxicity. Methods: A total of 40 Wistar albino rats were divided into five groups: control, K2Cr2O7(K2Cr2O715 mg/kg, one dose, i.p.), K2Cr2O7 + melatonin, K2Cr2O7 + CAPE, and K2Cr2O7 + melatonin + CAPE. Urine and blood samples were collected from rats before scarification. One kidney was collected for histopathological studies, and the other was stored at −80°C for further determination of catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), glutathione S-transferase (GST), and glutathione reductase (GR) levels with spectrophotometric method. Comet assay was used to evaluate the genotoxicity. Results: We observed a significant amelioration in genotoxicity by melatonin and simultaneous melatonin + CAPE treatment compared to K2Cr2O7 group (p1, p2< 0.05). SOD, CAT, GSH, GST, and MDA levels did not change when compared with controls. When K2Cr2O7 applied group was treated with melatonin and CAPE, neither melatonin nor CAPE made any changes in kidney GSH, GST, SOD, and MDA levels (P > 0.05). We noted that treatment with CAPE and melatonin + CAPE together caused a significant decrease in renal tissue damage, an upregulation in the kidney CAT levels (P < 0.05) and a slight healing at GR levels when compared with the K2Cr2O7 group. Conclusion: Our results revealed, CAPE and melatonin may have protective effects on K2Cr2O7 induced nephrotoxicity and cellular damage in rats. PMID:27756952

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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

  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).

  18. 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

  19. NTP toxicity studies of sodium dichromate dihydrate (CAS No. 7789-12-0) administered in drinking water to male and female F344/N rats and B6C3F1 mice and male BALB/c and am3-C57BL/6 mice.

    PubMed

    Bucher, John R

    2007-01-01

    Sodium dichromate dihydrate is one of a number of inorganic compounds containing hexavalent chromium (CR VI) found in drinking water supplies as a contaminant resulting from various industrial processes including electroplating operations, leather tanning, and textile manufacturing. Because of the lack of adequate experimental data on the toxicity and carcinogenicity of hexavalent chromium ingested orally, and because hexavalent chromium has been found in human drinking water supplies, the California Congressional delegation and the California Environmental Protection Agency nominated hexavalent chromium to the NTP for study. In study 1, male and female F344/N rats and B6C3F1 mice were exposed to sodium dichromate dihydrate (greater than 99% pure) in drinking water for 3 months. In study 2, sodium dichromate dihydrate was administered in drinking water to male B6C3F1, BALB/c, and am3-C57BL/6 mice for 3 months. Genetic toxicology studies were conducted in Salmonella typhimurium, Escherichia coli, and mouse peripheral blood erythrocytes. In study 1, groups of 10 male and 10 female F344/N rats and B6C3F1 mice were given drinking water containing 0, 62.5, 125, 250, 500, or 1,000 mg sodium dichromate dihydrate/L for 3 months (equivalent to average daily doses of approximately 5, 10, 17, 32, or 60 mg sodium dichromate dihydrate/kg body weight to rats and 9, 15, 26, 45, or 80 mg/kg to mice). On a molecular weight basis, these doses are equivalent to approximately 1.7, 3.5, 5.9, 11.2, and 20.9 mg hexavalent chromium/kg body weight per day to rats and 3.1, 5.2, 9.1, 15.7, and 27.9 mg/kg per day to mice. Additional groups of 10 rats per sex were exposed to the same concentrations of sodium dichromate dihydrate for 4 weeks. All rats and mice survived to the end of the study. Reduced body weights occurred in 500 and 1,000 mg/L male rats, 1,000 mg/L female rats, and in male and female mice exposed to 125 mg/L or greater. Water consumption by male and female rats exposed to 250

  20. NTP toxicity studies of sodium dichromate dihydrate (CAS No. 7789-12-0) administered in drinking water to male and female F344/N rats and B6C3F1 mice and male BALB/c and am3-C57BL/6 mice.

    PubMed

    Bucher, John R

    2007-01-01

    Sodium dichromate dihydrate is one of a number of inorganic compounds containing hexavalent chromium (CR VI) found in drinking water supplies as a contaminant resulting from various industrial processes including electroplating operations, leather tanning, and textile manufacturing. Because of the lack of adequate experimental data on the toxicity and carcinogenicity of hexavalent chromium ingested orally, and because hexavalent chromium has been found in human drinking water supplies, the California Congressional delegation and the California Environmental Protection Agency nominated hexavalent chromium to the NTP for study. In study 1, male and female F344/N rats and B6C3F1 mice were exposed to sodium dichromate dihydrate (greater than 99% pure) in drinking water for 3 months. In study 2, sodium dichromate dihydrate was administered in drinking water to male B6C3F1, BALB/c, and am3-C57BL/6 mice for 3 months. Genetic toxicology studies were conducted in Salmonella typhimurium, Escherichia coli, and mouse peripheral blood erythrocytes. In study 1, groups of 10 male and 10 female F344/N rats and B6C3F1 mice were given drinking water containing 0, 62.5, 125, 250, 500, or 1,000 mg sodium dichromate dihydrate/L for 3 months (equivalent to average daily doses of approximately 5, 10, 17, 32, or 60 mg sodium dichromate dihydrate/kg body weight to rats and 9, 15, 26, 45, or 80 mg/kg to mice). On a molecular weight basis, these doses are equivalent to approximately 1.7, 3.5, 5.9, 11.2, and 20.9 mg hexavalent chromium/kg body weight per day to rats and 3.1, 5.2, 9.1, 15.7, and 27.9 mg/kg per day to mice. Additional groups of 10 rats per sex were exposed to the same concentrations of sodium dichromate dihydrate for 4 weeks. All rats and mice survived to the end of the study. Reduced body weights occurred in 500 and 1,000 mg/L male rats, 1,000 mg/L female rats, and in male and female mice exposed to 125 mg/L or greater. Water consumption by male and female rats exposed to 250

  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. Holograms recorded in dichromated with simple sugars

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    Sugars as glucose and fructose can be used to holographic record. These materials have the advantage to mix very well with K2Cr2O7.Holographic gratings recorded in sugars, were made by a lineal setup to producing interference pattern using a wavelength at 473 nm. These materials have the ability to register information in real time.

  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. 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.

  5. 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.

  6. Silver halide masters for transfer into large format dichromated gelatin (DCG) holograms

    NASA Astrophysics Data System (ADS)

    Unterseher, Fred D.; Muth, August; Deem, Rebecca E.

    1998-02-01

    Techniques used to create several large format, 50 X 60 cm, silver halide masters for transfer into a large format, 45 X 54 cm, DCG hologram are discussed. The subject, a fossilized dinosaur egg, is one of the largest such artifacts ever found. In order to present all facets of the subject, the outer egg shell, the articulated embryo bones and a model of an artist's concept of the embryo inside the shell, several masters were produced to create in the end a double exposure, multichannel transfer image. An emphasis is placed on a practical approach to the production of the holograms.

  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. 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.

  9. 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

  10. 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

  11. 40 CFR Table 1 to Subpart Nnnnnn... - HAP Emissions Sources

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... requirements of the General Provisions (40 CFR part 63, subpart A) as shown in the following table. ... produce sodium dichromate. b. Sodium dichromate crystallization unit. c. Sodium dichromate drying unit. 3... produce chromic acid. c. Chromic acid crystallization unit. d. Chromic acid dryer. 4. Chromic...

  12. 40 CFR Table 1 to Subpart Nnnnnn... - HAP Emissions Sources

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirements of the General Provisions (40 CFR part 63, subpart A) as shown in the following table. ... produce sodium dichromate. b. Sodium dichromate crystallization unit. c. Sodium dichromate drying unit. 3... produce chromic acid. c. Chromic acid crystallization unit. d. Chromic acid dryer. 4. Chromic...

  13. 40 CFR Table 1 to Subpart Nnnnnn... - HAP Emissions Sources

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... requirements of the General Provisions (40 CFR part 63, subpart A) as shown in the following table. ... produce sodium dichromate. b. Sodium dichromate crystallization unit. c. Sodium dichromate drying unit. 3... produce chromic acid. c. Chromic acid crystallization unit. d. Chromic acid dryer. 4. Chromic...

  14. 40 CFR Table 1 to Subpart Nnnnnn... - HAP Emissions Sources

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... requirements of the General Provisions (40 CFR part 63, subpart A) as shown in the following table. ... produce sodium dichromate. b. Sodium dichromate crystallization unit. c. Sodium dichromate drying unit. 3... produce chromic acid. c. Chromic acid crystallization unit. d. Chromic acid dryer. 4. Chromic...

  15. 40 CFR Table 1 to Subpart Nnnnnn... - HAP Emissions Sources

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... requirements of the General Provisions (40 CFR part 63, subpart A) as shown in the following table. ... produce sodium dichromate. b. Sodium dichromate crystallization unit. c. Sodium dichromate drying unit. 3... produce chromic acid. c. Chromic acid crystallization unit. d. Chromic acid dryer. 4. Chromic...

  16. 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...

  17. 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...

  18. Milk tester's dermatitis.

    PubMed

    Herzog, J; Dunne, J; Aber, R; Claver, M; Marks, J G

    1988-09-01

    Hand dermatitis is a frequent problem among workers in milk testing laboratories. An epidemiologic study was conducted at the Pennsylvania Dairy Herd Improvement Association Milk Testing Laboratory, where more than 300,000 milk samples are examined monthly for protein, butterfat, and "somatic" cells. These samples are preserved with potassium dichromate for transport from the farm to the laboratory. A survey of the laboratory was conducted and workers were interviewed. Eight of 16 subjects reported a history of occupationally exacerbated hand dermatitis. Three of 16 subjects had positive patch test results to potassium dichromate. Two of 15 subjects who underwent patch testing to milk preserved with potassium dichromate had positive reactions. None reacted to milk alone, bronopol, or Kathon CG. Two workers are receiving workers' compensation because of severe allergic contact dermatitis of the hands to potassium dichromate. We conclude that milk testing laboratory workers are at substantial risk for acquiring allergic contact dermatitis from milk preserved with potassium dichromate. PMID:2971694

  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, 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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)

  6. 40 CFR 63.11504 - Am I subject to this subpart?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... acetate sealing, sodium dichromate sealing, and manganese phosphate coating; and thermal spraying. (iv..., chromium, lead, manganese, and nickel, as defined in § 63.11511, “What definitions apply to this...

  7. 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.

  8. 21 CFR 175.390 - Zinc-silicon dioxide matrix coatings.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... removed by water washing. Iron oxide Lithium hydroxide Removed by water washing. Methyl orange As an acid-base indicator. Potassium dichromate Removed by water washing. Silica gel Sodium silicate Zinc,...

  9. 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.

  10. 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)

  11. 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)

  12. 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...

  13. 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...

  14. 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,...

  15. A color-reaction-based rapid screening for null activity of butyrylcholinesterase: a step toward point-of-care screening for succinylcholine apnea.

    PubMed

    Nagpal, Nitish; Chowdhary, Sheemona; Bhattacharyya, Rajasri; Banerjee, Dibyajyoti

    2015-01-01

    Succinylcholine apnea happens in cases of null butyrylcholinesterase activity after administration of preintubation succinylcholine. So far, there is no such popular test that can rapidly screen null butyrylcholinesterase activity from plasma. Development of a novel method for rapid screening of null butyrylcholinesterase activity of plasma samples was the objective of the current work. Dichromate reagent was added to 1-naphthol, 2-naphthol, phenol, and para-nitrophenol in separate aliquots and watched for the color formation. Plasma samples preincubated with and without selective butyrylcholinesterase inhibitor were mixed with 1-naphthylacetate and watched for color development after addition of dichromate reagent. Fitting of 1-naphthylacetate at the active site of butyrylcholinesterase was analyzed by using tools of computational biology. It was seen that 1-naphthol formed color with dichromate reagent in a concentration-dependent manner. Other phenols did not form color with dichromate reagent even at 500-µm concentrations. Plasma sample with and without selective butyrylcholinesterase inhibitor (tetra isopropyl pyrophosphoramide) was distinguishable by color formation when incubated with 1-naphthylacetate, followed by the addition of dichromate reagent. In silico analysis also showed that 1-naphthylacetate fitted well at the active site of butyrylcholinesterase. The developed method may be used for rapid screening for null butyrylcholinesterase activity at point of care.

  16. 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

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

    PubMed

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

    2015-08-19

    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.

  18. 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

  19. 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.

  20. Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

    PubMed Central

    Dubberke, Silke; Abbas, Muhammad

    2011-01-01

    Summary Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the key step. PMID:21512603

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Nile blue and brilliant cresyl blue as redox indicators in iron(II) titrations.

    PubMed

    Sriramam, K

    1975-01-01

    Nile Blue and Brilliant Cresyl Blue, two compounds related to diaminophenoxazine, have been studied as indicators in titrations of iron(II) with cerium(IV)(in hydrochloric, sulphuric and perchloric acid media), dichromate, vanadate and permanganate. They are particularly suited for titrations in a fairly concentrated sulphuric acid medium and for titrations with dilute solutions. A probable indicator mechanism is suggested.

  9. 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)

  10. 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…

  11. 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.

  12. 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...

  13. 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)

  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. 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)

  16. 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)

  17. 40 CFR 63.11505 - What parts of my plant does this subpart cover?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...; electropolishing; electroless plating or other non-electrolytic metal coating operations, such as chromate conversion coating, nickel acetate sealing, sodium dichromate sealing, and manganese phosphate coating. (2...) Process units that are subject to the requirements of 40 CFR part 63, subpart N (National...

  18. 40 CFR 63.11504 - Am I subject to this subpart?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... electroplating). (ii) Electroless or non-eletrolytic plating. (iii) Other non-electrolytic metal coating processes, such as chromate conversion coating, nickel acetate sealing, sodium dichromate sealing, and..., lead, manganese, and nickel, as defined in § 63.11511, “What definitions apply to this subpart?”...

  19. 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...

  20. 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…

  1. 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)

  2. 40 CFR 63.11412 - What definitions apply to this subpart?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... 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, 2011 CFR

    2011-07-01

    ... is mixed with alkaline material (such as soda ash, sodium bicarbonate, and sodium hydroxide) and fed...? Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Bag... 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, 2013 CFR

    2013-07-01

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

  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. 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....

  9. 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)

  10. Electron energy loss spectroscopy elucidates the elusive darkening of zinc potassium chromate in Georges Seurat's A Sunday on La Grande Jatte--1884.

    PubMed

    Casadio, F; Xie, S; Rukes, S C; Myers, B; Gray, K A; Warta, R; Fiedler, I

    2011-03-01

    The color darkening of selected brushstrokes of Georges Seurat's A Sunday on La Grande Jatte--1884 was noted as early as 1892. Artificial aging of model systems containing zinc yellow (K(2)O·4ZnCrO(4)·3H(2)O) mixed with linseed oil successfully replicated the phenomena observed on La Grande Jatte. Electron energy loss spectroscopy measurements performed on the uppermost few microns of thin sections of the paint layers (obtained with focused ion beam milling) determined that samples which turned olive green (aged at 90% RH, with SO(2) and light) contain mostly the altered species Cr(III) and that the ochre-yellow coloration of specimens aged at 50% RH with SO(2) and light is due to the presence of dichromate ions (Cr (VI)). The altered species are only present in the first few microns of paint and are likely poorly crystalline, so that they eluded other types of bulk and surface measurements, but they create a substantial color alteration at the surface of the paint films. A similar phenomenon was confirmed on a sample from La Grande Jatte, where Cr(III) and Cr(VI) dichromate ions were detected in the ochre-colored, altered brushstrokes of zinc yellow. Laboratory simulations demonstrated that the equilibrium between chromate and dichromate ions is reversible within the paint film and that the orange dichromate ions can be transformed back into bright yellow chromates by exposure to highly alkaline gases. PMID:20953774

  11. 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)

  12. 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)

  13. 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...

  14. 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.

  15. 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.

  16. [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.

  17. A cell for high-precision constant-current coulometry with external generation of titrant.

    PubMed

    Knoeck, J; Diehl, H

    1969-05-01

    A cell has been designed for the high-precision coulometric titration, with externally generated titrant, of materials which otherwise undergo undesirable reactions at the working electrodes. With this cell potassium dichromate has been titrated, via its hydrolysis reaction, with hydroxyl ion generated at the cathode, cathodic reduction of the chromium(VI) being circumvented. In this cell 99.9% of the titrant required is generated in one chamber and transferred to another for reaction; the titration is then completed with titrant generated at a second, drip-type electrode working at much lower current. By means of commercially available Leeds and Northrup coulometric titration electrical equipment, titration of NBS 136b Potassium Dichromate gave a purity of 99.976%, standard deviation 0.005%, and of NBS 84d Potassium Acid Phthalate (done as a check) 99.991%, standard deviation 0.005%, both values being in excellent agreement with other work.

  18. [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

  19. 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.

  20. 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.

  1. 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.

  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. 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

  4. 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.

  5. 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.

  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. [Contact eczema and allergens: an analysis of the preliminary results of patch tests in the Dermatology Service of the National Hospital and University Center in Cotonou].

    PubMed

    Yedomon, H G; Fayomi, E B; Do Ango Padonou, F; Zohoun, T

    1998-06-01

    About a preliminary study of patch-test in 39 cases of contact dermatitis with allergens of international Contact Dermatitis Research (ICDRG), the authors noted 27 (69.2%) positive patch-tests. Men are frequently exposed to formaldehyde and dichromate potassium. Women are more exposed to fragrance-mix and formaldehyde. Hand workers have the uppermost percentage of positive patch-test (90.9%). The authors observed also 16 cases of contact polysensitivity for at least two allergens.

  8. Analysis of voltage effect on holographic gratings by modulation transfer function.

    PubMed

    Fontanilla-Urdaneta, Rosangela Coromoto; Olivares-Pérez, Arturo; Fuentes-Tapia, Israel; Ríos-Velasco, Mónica Areli

    2011-05-01

    The experimental data allow us to determine the imaging quality of holographic gratings with photosensitive film using organic material based on a polyvinyl alcohol matrix doped with potassium dichromate and nickel (II) chloride hexahydrate. The diffraction efficiency is estimated by different spatial frequencies, and the readout image quality is analyzed by the modulation transfer function. The experiment is carried out, with and without voltage application, at different spatial frequencies to obtain the image quality of photosensitive film.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. A cationic metal-organic framework consisting of nanoscale cages: capture, separation, and luminescent probing of Cr(2)O7(2-) through a single-crystal to single-crystal process.

    PubMed

    Li, Xinxiong; Xu, Hongyan; Kong, Fanzhen; Wang, Ruihu

    2013-12-16

    Dichromate capture: A 3D cationic metal-organic framework consisting of distorted octahedral and tetrahedral cages was constructed by using Ag(I) and 4,4'-bis(1,2,4-triazole). The complex exhibits fast exchange, high trapping capacity, and good selectivity for Cr2 O7 (2-) through single-crystal to single-crystal transformation. The complex also features a bluish violet luminescence that is distinctly quenched after Cr2 O7 (2-) exchange.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. High throughput cell-based assay for identification of glycolate oxidase inhibitors as a potential treatment for Primary Hyperoxaluria Type 1

    PubMed Central

    Wang, Mengqiao; Xu, Miao; Long, Yan; Fargue, Sonia; Southall, Noel; Hu, Xin; McKew, John C.; Danpure, Christopher J.; Zheng, Wei

    2016-01-01

    Glycolate oxidase (GO) and alanine:glyoxylate aminotransferase (AGT) are both involved in the peroxisomal glyoxylate pathway. Deficiency in AGT function causes the accumulation of intracellular oxalate and the primary hyperoxaluria type 1 (PH1). AGT enhancers or GO inhibitors may restore the abnormal peroxisomal glyoxylate pathway in PH1 patients. With stably transformed cells which mimic the glyoxylate metabolic pathway, we developed an indirect glycolate cytotoxicity assay in a 1,536-well plate format for high throughput screening. This assay can be used to identify compounds that reduce indirect glycolate-induced cytotoxicity by either enhancing AGT activity or inhibiting GO. A pilot screen of 4,096 known compounds identified two membrane permeable GO inhibitors: dichromate salt and colistimethate. We also developed a GO enzyme assay using the hydrogen peroxide-Amplex red reporter system. The IC50 values of potassium dichromate, sodium dichromate, and colistimethate sodium were 0.096, 0.108, and 2.3 μM in the GO enzyme assay, respectively. Further enzyme kinetic study revealed that both types of compounds inhibit GO activity by the mixed linear inhibition. Our results demonstrate that the cell-based assay and GO enzyme assay developed in this study are useful for further screening of large compound libraries for drug development to treat PH1. PMID:27670739

  19. 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.

  20. Common contact sensitizers in Chandigarh, India. A study of 200 patients with the European standard series.

    PubMed

    Sharma, V K; Chakrabarti, A

    1998-03-01

    200 patients (122 male, 78 female) with suspected allergic contact dermatitis were patch tested with the European standard series (ESS) and the results compared with other Asian centres. 131 (65.5%) patients showed 1 or more patch test positives to the ESS. Patch tests were positive to all allergens except primin. Potassium dichromate was the most common allergen (20.5%) followed by nickel sulfate (16.5%), SQL mix (14%), PPD (11.5%), cobalt (8%), fragrance mix (7.5%), formaldehyde (6.5%), colophony (5.5%), neomycin sulfate and mercapto mix (5% each). In women, nickel sulfate was the commonest allergen (30.8%) followed by SQL mix (16.7%) and potassium dichromate (15.4%). In men, potassium dichromate was the commonest sensitizer (23.8%) followed by SQL mix and PPD (12.3% each). Our results are at variance with other centres in Asia. SQL mix was able to detect less than 1/2 (42.2%) of patients allergic to ethanolic dilutions of ether extracts of parthenium. We conclude that the European standard series, with exclusion of primin, is suitable for detection of allergic contact dermatitis in India. However, SQL mix is not a adequate screen for parthenium sensitivity and patch testing with extracts of the plant should be continued, wherever indicated.

  1. Viability of preserved Cryptosporidium baileyi oocysts

    PubMed Central

    Surl, Chan-Gu; Kim, Se-Min

    2003-01-01

    The present study was undertaken to determine the viability and infectivity of oocysts of Cryptosporidium baileyi that had been stored from 1 to 40 months at 4℃ preserved in 2.5% potassium dichromate solution. Oocysts of C. baileyi were purified from the feces of experimentally infected chickens using discontinuous sucrose gradients. Subsequently, the purified oocysts were suspended in 2.5% potassium dichromate solution at a concentration of 1 × 107 organism/ml, and their viabilities were assessed by nucleic acid staining, histologic examination, and infectivity to 2-day-old chickens. All chickens inoculated with oocysts that had been stored for 1-18 months developed patent infections, while chickens infected with older oocysts remained uninfected. Between 5.8% and 82.2% of the oocysts, stored at 4℃ in 2.5% potassium dichromate solution, were found to be viable, as determined by nucleic acid staining. Parasite colonization in the bursa of Fabricius was detected in the microvillus border of bursal epithelium. The finding that C. baileyi oocysts remain infective to chickens for at least 18 months offers important time-saving advantages to investigators who frequently require large numbers of oocysts. PMID:14699260

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Prevalence of delayed hypersensitivity to the European standard series in a self-selected population.

    PubMed

    Greig, J E; Carson, C F; Stuckey, M S; Riley, T V

    2000-05-01

    There are limited reports of the prevalence of positive reactions in healthy adults to patch tests with standard allergens; there are no recent comprehensive studies from Australia. Healthy adult volunteers (n = 219) from the Western Australian community were patch tested using the European standard series of allergens. Seventy-seven (35%) reacted to at least one allergen, positive patch tests being most prevalent to nickel sulfate (20%), potassium dichromate (9%), cobalt chloride (6%) and fragrance mix (4%). Prevalence of positive patch tests to nickel and chromate was higher than that reported for another healthy population, which may stem from self-selection of volunteers or geographical differences, including extent of exposure to allergens.

  8. 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

  9. 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.

  10. 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/.

  11. 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.

  12. Induced and Form Birefringence in High-Frequency Polarization Gratings

    NASA Astrophysics Data System (ADS)

    Martinez-Ponce, Geminiano; Solano, Cristina

    2001-08-01

    High-frequency phase polarization gratings are fabricated holographically in dichromated gelatin dyed with malachite green. It is observed that the intensity of the -1 diffracted beam is a sinusoidal function of the incident polarization angle. In addition, we analyze the dependence of the diffracted order polarization on grating frequency. It is evident from our results that form birefringence becomes significant when the grating period is smaller than the illumination wavelength, thus modifying the optically induced birefringence. Then, in polarization hologram reconstruction, it is not possible to obtain the polarization distribution at the recording step for high-frequency objects.

  13. 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.

  14. 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

  15. Spectrally nonselective holographic objective

    NASA Astrophysics Data System (ADS)

    Wardosanidze, Zurab V.

    1991-10-01

    Reflection holograms and holographic optical elements fabricated by the Denisyuk method are spectrally selective. In certain applications there may be a need for the development of holographic structures that are not selective in terms of the spectral composition of the reconstructing light. This paper describes the possibility of creating spectral nonselective optical elements and reflection holograms on a dichromate gelatin layer (DGL). The essential condition for achieving nonselectivity in this case is a strong absorption of actinic radiation in the initial emulsion layer conditioning the strongly damping character of the summary field in thickness.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Review of the design and manufacturing procedures for large-format holographic optical elements

    NASA Astrophysics Data System (ADS)

    Stojanoff, Christo G.; Schuette, Hartmut; Schulat, Jochen; Froning, Philipp

    1998-10-01

    The objective of this research program was the development of the technology for the industrial manufacturing of HOEs for technical applications such as: holographic solar concentrators for utilization in photovoltaic energy conversion and solar photochemistry, and integrated holographic stacks for daylighting, glazing and shading in buildings. Some of the fabricated HOEs exhibit apertures in the order of 8 square meters. The accomplished technology facilitates the continuous fabrication of the holographic films on glass or plastic substrata. The standard holographic material we use for the fabrication of HOEs is dichromated gelatin (DCG) on glass or plastic film (PET) substrata. The dichromated gelatin layer could be prepared with different compositions to accommodate the desired exposures and chemical processing procedures. At present we manufacture holographic plates on glass substrata in sizes of up to 1 meter square. The holographic film on plastic substratum is 20 cm wide and could be made in lengths of hundredths of meters. The inexpensive fabrication of such large formats is attained by automation of the entire process: film manufacturing, hologram copying, development and test. We present in this paper the design considerations and the developed manufacturing procedures. These comprise the fabrication of large format reflective holograms for concentrating mirrors and the copying of transmissive holograms, such as gratings and lenses, using in-plane contact copying in checkerboard arrangement or rotating drum continuous copying onto an endless plastic film.

  6. 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.

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

    SciTech Connect

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

    1995-03-01

    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.

  8. 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.

  9. 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

  10. Is the European standard series suitable for patch testing in Riyadh, Saudi Arabia?

    PubMed

    el-Rab, M O; al-Sheikh, O A

    1995-11-01

    Due to the lack of a regional patch test series in our geographical area, the suitability of the European standard series was evaluated by patch testing dermatitis patients in Riyadh, Saudi Arabia. Of 240 consecutive patients with various forms of dermatitis, 136 (57%) showed 1 or more positive patch tests, women, 74 (54%), slightly outnumbering men, 62 (46%). Positive reactions were found to 21 of the 22 items in the test series. Sensitization was most common to nickel sulfate (51 = 37.5%), potassium dichromate (48 = 35%) and cobalt chloride (43 = 32%) The frequency of sensitization to nickel was higher in women (41 = 30%) while that to dichromate was higher in men (39 = 29%). Less reactions were found to fragrance mix (21 = 15%), formaldehyde (15 = 11%) and neomycin sulfate (15 = 11%). Sensitization to other allergens ranged between 10 and 1%. Less than 1% of patients (0.7%) reacted to benzocaine and none to primin. The frequency of occurrence of multiple sensitivities is also presented. We conclude that the European standard series is suitable for patch testing dermatitis patients in our region, with the exception of benzocaine and primin. The addition of 3 allergens that could be of local relevance is discussed.

  11. 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

  12. 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

  13. 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.

  14. Bernauer's bands.

    PubMed

    Shtukenberg, Alexander; Gunn, Erica; Gazzano, Massimo; Freudenthal, John; Camp, Eric; Sours, Ryan; Rosseeva, Elena; Kahr, Bart

    2011-06-01

    Ferdinand Bernauer proposed in his monograph, "Gedrillte" Kristalle (1929), that a great number of simple, crystalline substances grow from solution or from the melt as polycrystalline spherulites with helically twisting radii that give rise to distinct bull's-eye patterns of concentric optical bands between crossed polarizers. The idea that many common molecular crystals can be induced to grow as mesoscale helices is a remarkable proposition poorly grounded in theories of polycrystalline pattern formation. Recent reinvestigation of one of the systems Bernauer described revealed that rhythmic precipitation in the absence of helical twisting accounted for modulated optical properties [Gunn, E. et al. J. Am. Chem. Soc. 2006, 128, 14234-14235]. Herein, the Bernauer hypothesis is re-examined in detail for three substances described in "Gedrillte" Kristalle, potassium dichromate, hippuric acid, and tetraphenyl lead, using contemporary methods of analysis not available to Bernauer, including micro-focus X-ray diffraction, electron microscopy, and Mueller matrix imaging polarimetry. Potassium dichromate is shown to fall in the class of rhythmic precipitates of undistorted crystallites, while hippuric acid spherulites are well described as helical fibrils. Tetraphenyl lead spherulites grow by twisting and rhythmic precipitation. The behavior of tetraphenyl lead is likely typical of many substances in "Gedrillte" Kristalle. Rhythmic precipitation and helical twisting often coexist, complicating optical analyses and presenting Bernauer with difficulties in the characterization and classification of the objects of his interest.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. Automated in-syringe single-drop head-space micro-extraction applied to the determination of ethanol in wine samples.

    PubMed

    Srámková, Ivana; Horstkotte, Burkhard; Solich, Petr; Sklenářová, Hana

    2014-05-30

    A novel approach of head-space single-drop micro-extraction applied to the determination of ethanol in wine is presented. For the first time, the syringe of an automated syringe pump was used as an extraction chamber of adaptable size for a volatile analyte. This approach enabled to apply negative pressure during the enrichment step, which favored the evaporation of the analyte. Placing a slowly spinning magnetic stirring bar inside the syringe, effective syringe cleaning as well as mixing of the sample with buffer solution to suppress the interference of acetic acid was achieved. Ethanol determination was based on the reduction of a single drop of 3mmol L(-1) potassium dichromate dissolved in 8mol L(-1) sulfuric acid. The drop was positioned in the syringe inlet in the head-space above the sample with posterior spectrophotometric quantification. The entire procedure was carried out automatically using a simple sequential injection analyzer system. One analysis required less than 5min including the washing step. A limit of detection of 0.025% (v/v) of ethanol and an average repeatability of less than 5.0% RSD were achieved. The consumption of dichromate reagent, buffer, and sample per analysis were only 20μL, 200μL, and 1mL, respectively. The results of real samples analysis did not differ significantly from those obtained with the references gas chromatography method.

  3. 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.

  4. Analytical applications of condensed phosphoric acid-I Determination of ferrous and total iron in iron ores after decomposition with condensed phosphoric acid.

    PubMed

    Mizoguchi, T; Ishii, H

    1978-06-01

    A simple method is described for the determination of ferrous and total iron in iron ores. Iron ores are dissolved by condensed phosphoric acid (CPA) very rapidly without any tedious and time-consuming manipulations such as elimination of silica and filtration. Under the proposed conditions (amount of sample 100 mg, amount of CPA added 10 g, heating temperature 290 degrees , heating time 30 min), magnetite, limonite and hematite are completely dissolved. The iron content can be determined in the presence of condensed phosphoric acid by titration with dichromate solution, if a slight modification is made. The total iron in iron ores, determined by the present method, is in agreement with that found by the JIS method. The ferrous iron in iron ores can be determined by dissolving the samples with CPA in a nitrogen atmosphere and titrating with dichromate solution. Chelatometric titration of iron after solvent extraction with MIBK from solutions prepared by use of CPA is found to be accurate for samples such as pyrite cinder. The ability of CPA to dissolve various materials has been investigated.

  5. Magnetoelectric Control of Exchange Coupling in Monodomain BiFeO3 Heterostructures

    NASA Astrophysics Data System (ADS)

    Irwin, Julian; Saenrang, W.; Davidson, B.; Ryu, S.; Baek, S.-B.; Eom, C. B.; Rzchowski, M. S.; Freeland, J.

    2014-03-01

    The electric field control of magnetization via the exchange bias coupling of a ferromagnetic and antiferromagnetic orderings has exciting applications in spintronic devices such as magnetic tunnel junctions. We investigate the exchange coupling between the monodomain multiferroic BiFeO3(BFO) thin film and a ferromagnetic Co layer. Recently, X-ray magnetic circular dichromism (XMCD) has been used to observe a ~20° rotation in the magnetization of the Co when the electric polarization of the BFO is reversed. Due to the formation of an antiferromagnetic surface ``dead layer'' at high temperatures, observed using X-ray linear magnetic dichromism, this rotation is only seen at temperatures below ~150K. Here we investigate the exchange coupling using anisotropic magnetoresistance (AMR) measurements that detect changes in the magnetization of the Co layer. Out approach using AMR can be applied more generally to study exchange coupling in multiferroic systems. This work is supported by the Army Research Office under Grant No. W911NF-10-1-0362.

  6. Purification and chromium-excretory function of low-molecular-weight, chromium-binding substances from dog liver.

    PubMed

    Wada, O; Wu, G Y; Yamamoto, A; Manabe, S; Ono, T

    1983-10-01

    From liver of dogs injected iv with potassium dichromate (38 mg/kg body wt), a low-molecular-weight chromium-binding substance (LMCr) was purified into two subfractions, LMCr I and LMCr II, which differ in physical and chemical properties. LMCr I was identified to be an anionic, organic chromium compound with a molecular weight of 1500. It contained glutamic acid, glycine, and cysteine as the predominant amino acids and firmly bound chromium in a ratio of one chromium(III) to one molecule of LMCr I. LMCr II was isolated in crystalline form and demonstrated to be a water-soluble, inorganic chromium(III) complex consisting of Na2HPO4 . 7H2O and Na2HPO4 . 2H2O. Although its crystallization reduced the chromium content, it had a maximum chromium-binding capacity as much as one chromium per one phosphorus in water. The mixture of LMCr I and LMCr II as approximated to be the natural composition showed a lower acute toxicity as measured by lethality in mice and had higher rates of urinary excretion and renal clearance in rabbits, accompanied by lower rates of renal tubular reabsorption and retention in kidney and liver than potassium dichromate(VI) and chromium(III) chloride. Pretreatment with chromium-free LMCr II remarkably reduced the mortality rates of mice acutely poisoned with chromium chloride. These results indicate that LMCr plays an important role in the detoxification and excretion of chromium in mammals. PMID:6617615

  7. 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

  8. Silver halide sensitized gelatin derived from BB-640 holographic emulsion.

    PubMed

    Neipp, C; Pascual, I; Beléndez, A

    1999-03-10

    Silver halide sensitized gelatin (SHSG) is one of the most interesting techniques for the production of holographic optical elements, achieving relatively high sensitivity of photographic material with a low scattering of dichromated gelatin. Here we present experimental results for SHSG derived from the novel BB-640, a red-sensitive ultra-fine-grain emulsion from Holographic Recording Technologies (Steinau, Germany). The material is characterized before recording and after processing, and information about the thickness, absorption, and refractive-index modulation of the final holograms is obtained. The influence of the developer is analyzed, and diffraction efficiencies as great as 96.2% (after allowing for reflections) with a transmission of 1% and absorption and scatter losses of 2.8% are obtained with AAC developer. Our investigations reveal that high-quality SHSG transmission holograms may be obtained with the new BB-640 plates.

  9. 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.

  10. 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.

  11. Circadian reduction of chromium in the gastric environment.

    PubMed

    De Flora, S; Badolati, G S; Serra, D; Picciotto, A; Magnolia, M R; Savarino, V

    1987-11-01

    Samples of gastric juice from variously treated subjects efficiently reduced hexavalent chromium and decreased its mutagenicity. Chromium reduction was due to thermostable components of gastric secretions and was favoured by the acidity of the intragastric environment. The circadian monitoring of pH and of chromium reduction, as assessed by colorimetric analysis at hourly intervals, showed a basal activity (less than 10 micrograms/ml gastric juice) during the night and interdigestive periods, and peaks (tens of micrograms/ml) during the 3-4-h periods after each meal. Assays in the Ames reversion test confirmed that the decrease in mutagenicity of sodium dichromate produced by gastric juice was significantly enhanced after meals. This physiological mechanism is expected to provide an important protective barrier against the oral toxicity of this metal, and may explain its lack of oral carcinogenicity.

  12. 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.

  13. 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.

  14. GFAAS determination of ultratrace quantities of organotins in sea-water by using enhancement methods.

    PubMed

    Parks, E J; Blair, W R; Brinckman, F E

    1985-08-01

    Tributyltin in sea-water is preconcentrated by extraction into toluene and determined by enhanced graphite-furnace atomic-absorption (GFAAS) at ultratrace concentrations (as low as 1.0 mug l .) equal to or lower than the toxic limits for aquatic organotins. Toluene is preferred to MIBK, chloroform or hexane as the solvent. Sea salts, in concentrations as low as 0.1%, critically interfere with GFAAS tin determinations, and must be removed by washing the extract with demineralized water. Signal enhancement effected by inserting L'vov platforms in the graphite furnace tubes or by adding ammonium dichromate to the analyte solution is nearly additive when both methods of enhancement are combined.

  15. 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.

  16. Optical interconnects for multiprocessors in computer backplane

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Jin; Tu, Kun-Yii; Ramsey, Darrell; Oh, Tchang-Hun; Kostuk, Raymond K.

    1995-04-01

    Optical interconnects have potential advantage over electrical methods at the backplane level. In this paper we present a free-space optical connection cube for backplane interconnect applications. The connection cube has a symmetric structure which reduces skew between boards. It can be expanded into a 3-dimensional configuration for parallel communication using vertical-cavity surface-emitting laser (VCSEL) and receiver arrays. Fan-out and fan-in of propagation beams for the connection cube are realized using volume holographic optical elements formed in dichromated gelatin (DCG) emulsion. A four-port communication system has been demonstrated using the connection cube and tested at 500 MHz. In this paper, advantages and detailed implementation of the free-space optical connection cube are presented. Design considerations for fan-out/in holographic gratings and alignment tolerances for the connection cube are discussed. Characteristics of the connection cube are also presented.

  17. 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.

  18. 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.

  19. Phase holograms formed by silver halide /sensitized/ gelatin processing

    NASA Astrophysics Data System (ADS)

    Graver, W. R.; Gladden, J. W.; Eastes, J. W.

    1980-05-01

    A novel recording process for the formation of phase volume holograms at up to 1500 cycles/mm is described. The term silver halide (sensitized) gelatin or SHG denotes an all-gelatin phase material, which records the initial image information through photon absorption by the silver halide. Our process uses a reversal bleach that dissolves the developed silver image and cross-links the gelatin molecules in the vicinity of the developed image. Experiments have determined the stored image as refractive-index differences within the remaining gelatin. The major attributes of SHG holograms are (1) panchromatic response, (2) 100:1 greater light sensitivity than dichromate (sensitized) gelatin, and (3) elimination of darkening (printout) effects.

  20. 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.

  1. 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.

  2. Chemical reduction of europium(III) in hydrochloric acid

    SciTech Connect

    Atanasyants, A.G.; Gurinov, Yu.S.; Sofenina, E.V.

    1988-07-10

    The authors have devised a method for use at set pH and temperature, in which the volume of hydrogen produced is recorded and samples are taken for europium(II) analysis. The solution is poured into a glass cell with a thermostatic jacket; argon is passed through a capillary tube 2 for 0.5 h before the reduction is started, with the bubbling rate determined from the change in level in a burette. This burette is also used to record the hydrogen volume. The europium(II) concentration is determined by titration with potassium dichromate by a standard method. Europium is reduced by zinc in acid solution. The zinc consumption in hydrogen production can be reduced by operating at pH 2-3, with the precipitant introduced after the reaction starts.

  3. Increased anatomical detail by in vitro MR microscopy with a modified Golgi impregnation method.

    PubMed

    Zhang, Xiaowei; Bearer, Elaine L; Perles-Barbacaru, Adriana T; Jacobs, Russell E

    2010-05-01

    Golgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although there is some differential uptake of the standard small-molecular-weight contrast agents by different tissue types, detailed discrimination of tissue architecture in MR images does not approach that of standard histology. Our modified Golgi impregnation method significantly increases anatomic detail in magnetic resonance microscopy images. Fixed mouse brains were treated with a solution containing a paramagnetic contrast agent (gadoteridol) and potassium dichromate. Results demonstrate a specific contrast enhancement likely due to diamagnetic hexavalent chromium undergoing tissue specific reduction to paramagnetic trivalent chromium. This new method dramatically improves neuroanatomical contrast compared to conventional fixation, displaying detail approximating that of histologic specimens at low (4x) magnification.

  4. 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.

  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. 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

  7. 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

  8. 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

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

    PubMed

    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

  10. 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

  11. Design and optimization of a volume-phase holographic grating for simultaneous use with red, green, and blue light using unpolarized light.

    PubMed

    Mahamat, Adoum H; Narducci, Frank A; Schwiegerling, James

    2016-03-01

    Volume-phase holographic (VPH) gratings have been designed for use in many areas of science and technology, such as optical communication, optical imaging, and astronomy. In this paper, the design of a volume-phase holographic grating, simultaneously optimized to operate in the red, green, and blue wavelengths, is presented along with a study of its fabrication tolerances. The grating is optimized to produce 98% efficiency at λ=532  nm and at least 75% efficiency in the region between 400 and 700 nm, when the incident light is unpolarized. The optimization is done for recording in dichromated gelatin with a thickness of 12 μm, an average refractive index of 1.5, and a refractive index modulation of 0.022. PMID:26974620

  12. 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.

  13. Synthesis, structural and optical properties of Eskolaite nanoparticles derived from Cr doped polyanthranilic acid (CrPANA)

    NASA Astrophysics Data System (ADS)

    Hosny, Nasser Mohammed; Zoromba, Mohamed Shafick; Samir, Ghada; Alghool, Samir

    2016-10-01

    Cr doped polyanthranilic acid (Cr PANA) has been used as a molecular precursor of Cr2O3 nanoparticles. Potassium dichromate acted as an oxidant and a dopant in Cr PANA synthesis. The spectral, optical and thermal properties of the precursor have been described. Thermogravimetric Analysis (TGA) and differential scanning calorimetric (DSC) were used to clarify the thermal stability of Cr PANA. The optical band gap (Eg) measurements indicated that Cr PANA has wider optical band than the pure PANA. Calcination of Cr PANA at 600 °C produced Eskolaite (Cr2O3) nanoparticles. The obtained nanoparticles have been characterized by XRD and TEM. The average size of the nanoparticles was found to be 70 nm. The measured optical band gap of Eskolaite nanoparticles is 0.35 eV wider than the bulk.

  14. Determination of total mercury in biological and geological samples

    USGS Publications Warehouse

    Crock, James G.

    2005-01-01

    The analytical chemist is faced with several challenges when determining mercury in biological and geological materials. These challenges include widespread mercury contamination, both in the laboratory and the environment, possible losses of mercury during sample preparation and digestion, the wide range of mercury values commonly observed, ranging from the low nanogram per gram or per liter for background areas to hundreds of milligrams per kilogram in contaminated or ore-bearing areas, great matrix diversity, and sample heterogeneity1. These factors can be naturally occurring or anthropogenic, but must be addressed to provide a precise and accurate analysis. Although there are many instrumental methods available for the successful determination of mercury, no one technique will address all problems or all samples all of the time. The approach for the determination of mercury used at the U.S. Geological Survey, Crustal Imaging and Characterization Team, Denver Laboratories, utilizes a suite of complementary instrumental methods when approaching a study requiring mercury analyses. Typically, a study could require the analysis of waters, leachates or selective digestions of solids, vegetation, and biological materials such as tissue, bone, or shell, soils, rocks, sediments, coals, sludges, and(or) ashes. No one digestion or sample preparation method will be suitable for all of these matrices. The digestions typically employed at our laboratories include: (i) a closed-vessel microwave method using nitric acid and hydrogen peroxide, followed by digestion/dilution with a nitric acid/sodium dichromate solution, (ii) a robotic open test-tube digestion with nitric acid and sodium dichromate, (iii) a sealed Teflon? vessel with nitric acid and sodium dichromate, (iv) a sealed glass bottle with nitric acid and sodium dichromate, or (v) open test tube digestion with nitric and sulfuric acids and vanadium pentoxide. The common factor in all these digestions is that they are

  15. Genome-wide gene expression profiling of acute metal exposures in male zebrafish.

    PubMed

    Baer, Christine E; Ippolito, Danielle L; Hussainzada, Naissan; Lewis, John A; Jackson, David A; Stallings, Jonathan D

    2014-12-01

    To capture global responses to metal poisoning and mechanistic insights into metal toxicity, gene expression changes were evaluated in whole adult male zebrafish following acute 24 h high dose exposure to three metals with known human health risks. Male adult zebrafish were exposed to nickel chloride, cobalt chloride or sodium dichromate at concentrations corresponding to their respective 96 h LC20, LC40 and LC60 (i.e. 96 h concentrations at which 20%, 40% and 60% lethality is expected, respectively). Histopathology was performed on a subset of metal-exposed zebrafish to phenotypically anchor transcriptional changes associated with each metal exposure. Here we describe in detail the contents and quality controls for the gene expression and other data associated with the study published by Hussainzada and colleagues in BMC Pharmacology and Toxicology (Hussainzada et al., 2014) with the data uploaded to Gene Expression Omnibus (accession number GSE50648).

  16. Genome-wide gene expression profiling of acute metal exposures in male zebrafish

    PubMed Central

    Baer, Christine E.; Ippolito, Danielle L.; Hussainzada, Naissan; Lewis, John A.; Jackson, David A.; Stallings, Jonathan D.

    2014-01-01

    To capture global responses to metal poisoning and mechanistic insights into metal toxicity, gene expression changes were evaluated in whole adult male zebrafish following acute 24 h high dose exposure to three metals with known human health risks. Male adult zebrafish were exposed to nickel chloride, cobalt chloride or sodium dichromate at concentrations corresponding to their respective 96 h LC20, LC40 and LC60 (i.e. 96 h concentrations at which 20%, 40% and 60% lethality is expected, respectively). Histopathology was performed on a subset of metal-exposed zebrafish to phenotypically anchor transcriptional changes associated with each metal exposure. Here we describe in detail the contents and quality controls for the gene expression and other data associated with the study published by Hussainzada and colleagues in BMC Pharmacology and Toxicology (Hussainzada et al., 2014) with the data uploaded to Gene Expression Omnibus (accession number GSE50648). PMID:26484131

  17. Grisms Developed for FOCAS

    NASA Astrophysics Data System (ADS)

    Ebizuka, Noboru; Kawabata, Koji S.; Oka, Keiko; Yamada, Akiko; Kashiwagi, Masako; Kodate, Kashiko; Hattori, Takashi; Kashikawa, Nobunari; Iye, Masanori

    2011-03-01

    Faint Object Camera and Spectrograph (FOCAS) is a versatile common-use optical instrument for the 8.2 m Subaru Telescope, offering imaging and spectroscopic observations. FOCAS employs grisms with resolving powers ranging from 280 to 8200 as dispersive optical elements. A grism is a direct-vision grating composed of a transmission grating and prism(s). FOCAS has five grisms with replica surface-relief gratings including an echelle-type grism, and eight grisms with volume-phase holographic (VPH) gratings. The size of these grisms is 110 mm × 106 mm in aperture with a maximum thickness of 110 mm. We employ not only the dichromated gelatin, but also the hologram resin as a recording material for VPH gratings. We discuss the performance of these FOCAS grisms measured in the laboratory, and verify it by test observations, and show examples of astronomical spectroscopic observations.

  18. 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.

  19. Dense silica coatings on ceramic powder particles

    SciTech Connect

    Opitz, J.F.A.; Mayr, W.

    1995-09-01

    Dense silica coatings on the surface of inorganic powders particles are prepared by the hydrolysis of tetraethoxysilane (TEOS) in alcoholic suspensions. In a first reaction step, the TEOS is pre-hydrolysed in acidic solution and afterwards, a suspension of powder particles in this reaction solution is treated with ammonia which results in a dense silica coating of typically 10 - 100 nm thickness. Different luminescent powders which are used in the manufacture of cathode-ray tubes or fluorescent lamps have been coated by this procedure. The silica coating forms a transparent layer and the suspension properties of the coated powders are determined by the silica layer. The silica coating also protects sulfidic luminescent powders from being attacked by oxidizing agents like dichromate ions which are used in the suspension formulations for TV tube fabrication.

  20. Increased Anatomical Detail by In Vitro MR Microscopy With a Modified Golgi Impregnation Method

    PubMed Central

    Zhang, Xiaowei; Bearer, Elaine L.; Perles-Barbacaru, Adriana T.; Jacobs, Russell E.

    2010-01-01

    Golgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although there is some differential uptake of the standard small-molecular-weight contrast agents by different tissue types, detailed discrimination of tissue architecture in MR images does not approach that of standard histology. Our modified Golgi impregnation method significantly increases anatomic detail in magnetic resonance microscopy images. Fixed mouse brains were treated with a solution containing a paramagnetic contrast agent (gadoteridol) and potassium dichromate. Results demonstrate a specific contrast enhancement likely due to diamagnetic hexavalent chromium undergoing tissue specific reduction to paramagnetic trivalent chromium. This new method dramatically improves neuroanatomical contrast compared to conventional fixation, displaying detail approximating that of histologic specimens at low (4×) magnification. PMID:20432310

  1. Some consideration on potentials of coal organic materials for chemicals

    SciTech Connect

    Nomura, Masakatsu; Artok, Levent; Su, Yan; Murata, Satoru

    1998-12-31

    According to the recent structural studies on bituminous coals, the presence of condensed aromatic nuclei and alicyclic portion in coal is considered to be more abundant than believed so far. Based on these data consideration of the potential of coal for chemical production is made by referring to the results on sodium dichromate-oxidation of Akabira coal and detailed analysis of vacuum residue from Illinois No.6 coal derived liquid. It is also stressed that to select the appropriate coal samples for either flash pyrolysis or hydroliquefaction based on their detailed structural index is important to attain their effective conversion. Three methods occurs in the minds of coal chemists, pyrolysis, direct liquefaction and indirect liquefaction. In this paper, the authors focus on the former two methods because indirect liquefaction makes use of carbon monoxide and hydrogen obtained in coal gasification, being not fitted in the present context of potentials of coal organic materials.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Dosimetry for radiation processing

    NASA Astrophysics Data System (ADS)

    Miller, Arne

    During the past few years significant advances have taken place in the different areas of dosimetry for radiation processing, mainly stimulated by the increased interest in radiation for food preservation, plastic processing and sterilization of medical products. Reference services both by international organizations (IAEA) and national laboratories have helped to improve the reliability of dose measurements. Several dosimeter systems like calorimetry, perspex, and radiochromic dye films are being improved and new systems have emerged, e.g. spectrophotometry of dichromate solution for reference and sterilization dosimetry, optichromic dosimeters in the shape of small tubes for food processing, and ESR spectroscopy of alanine for reference dosimetry. In this paper the special features of radiation processing dosimetry are discussed, several commonly used dosimeters are reviewed, and factors leading to traceable and reliable dosimetry are discussed.

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

    PubMed

    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.

  12. Determination of carbon-14-labeled 3,4-benzopyrene adsorbed on different solids

    SciTech Connect

    Janssen, F.; Kanij, J.

    1983-09-01

    Recovery studies for 3,4-benzopyrene (BaP) are necessary for quantifying polynuclear aromatic hydrocarbons on solid matrices. One of the main problems in recovery studies is the simulation of samples, on which a known quantity of BaP is adsorbed and homogeneously divided on solid substrates. In this study the samples were spiked by the addition of a toluene solution containing /sup 14/C-BaP, taking into account that BaP was not homogeneously divided on the adsorbent. The samples were treated by two destruction methods, i.e., a wet destruction with a potassium dichromate-sulfuric acid and orthophosphoric acid and a combustion with oxygen. The liberated CO/sub 2/ was adsorbed and the /sup 14/C radioactivity analyzed by means of liquid scintillation counting. 6 references, 1 figure, 5 tables.

  13. Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part I. Transmission holographic optical elements.

    PubMed

    Kim, J M; Choi, B S; Kim, S I; Kim, J M; Bjelkhagen, H I; Phillips, N J

    2001-02-10

    Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOE's). The drawback of DCG is its low sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-high-resolution silver halide emulsions. An optimized processing technique for transmission HOE's recorded in these materials is introduced. Diffraction efficiencies over 90% can be obtained for transmissive diffraction gratings. Understanding the importance of the selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOE's.

  14. 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.

  15. Genotoxicity and antioxidant enzyme activity induced by hexavalent chromium in Cyprinus carpio after in vivo exposure.

    PubMed

    Kumar, Pavan; Kumar, Ravindra; Nagpure, Naresh S; Nautiyal, Prakash; Kushwaha, Basdeo; Dabas, Anurag

    2013-10-01

    Fish, being an important native of the aquatic ecosystem, are exposed to multipollution states and are therefore considered as model organisms for ecotoxicological studies of aquatic pollutants, including metal toxicity. We investigated oxidative stress (OS) in liver, kidney and gill tissues through antioxidant enzyme activities and genotoxicity induced in whole blood and gill tissues through comet assay and micronucleus (MN) test in Cyprinus carpio after 96-hour in vivo static exposure to potassium dichromate at three sublethal (SL) test concentrations, including SL-I [93.95 mg/L, i.e. one quarter of half-maximal lethal concentration (LC50)], SL-II (187.9 mg/L, i.e. one half of LC50), and SL-III (281.85 mg/L, i.e. three quarters of LC50), along with a control. The 96-hour LC50 value for potassium dichromate was estimated to be 375.8 mg/L in a static system in the test species. Tissues samples were collected at 24, 48, 72 and 96 hours postexposure. Results indicated that the exposed fish experienced OS as characterized by significant (p < 0.05) variation in antioxidant enzyme activities, as compared to the control. Activities of superoxide dismutase and glutathione peroxidase increased, whereas activity of catalase decreased with the progression of the experiment. The mean percent DNA damage in comet tail and MN induction in gills and whole blood showed a concentration-dependent increase up to 96-hour exposure. The findings of this study would be helpful in organ-specific risk assessment of Cr(VI)-induced OS and genotoxicity in fishes.

  16. 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).

  17. 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.

  18. 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.

  19. Changes in the pattern of sensitization to common contact allergens in denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies.

    PubMed

    Johansen, J d; Menné, T; Christophersen, J; Kaaber, K; Veien, N

    2000-03-01

    The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period. Attention is given to possible effects of preventive strategies introduced in Denmark regarding nickel and chromate sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0-18 years of age, the frequency of nickel allergy decreased from 24.8% in the first study period to 9.2% in the second study period (P < 0. 0008). Fragrance mix allergy doubled in frequency from 4.1% in 1985-86 to 9.9% in 1997-98, an increase that affected all age groups. Contact allergy to potassium dichromate decreased significantly from 3.0% in the first period to 1.2% in the second period (P = 0. 001). The decrease was seen in both sexes and was most pronounced among those of working age. No other significant changes were found in the frequency of sensitization to common allergens over the 12-year observation period.

  20. Patch tests in children: a review of 13 years of experience in comparison with previous data.

    PubMed

    Milingou, Maria; Tagka, Anna; Armenaka, Melina; Kimpouri, Konstantina; Kouimintzis, Dimitris; Katsarou, Alexandra

    2010-01-01

    The true prevalence of allergic contact dermatitis (ACD) in children remains unknown. Our aim was to compare the results of patch tests in children with suspected ACD between two different periods of time and identify possible changes in emerging allergens. We compared contact allergens, gender, age distribution, and personal history of atopic dermatitis (AD), in correlation with the positivity of patch tests, between two equal periods of time (232 children tested during 1980-1993, period A, and 255 children during 1994-2007, period B) in the same region and in the same institution. Patch test positivity was 47.8% in period A, and 60% in period B (p = 0.083). The most common allergens in period A were: nickel sulfate (16.3%), cobalt chloride (8.6%), fragrance mix (7.3%), potassium dichromate (4.3%), and thimerosal only (1.7%). In period B, the allergen distribution was as follows: nickel sulfate (21.56%), thimerosal (18.03%), cobalt chloride (12.9%), potassium dichromate (9.4%), and fragrance mix (4.7%). Girls were more likely to have a positive patch test compared with boys, with reactions in 53% of girls and 39% of boys in period A (p = 0.003), and 61% of girls and 58% of boys in period B (p = 0.691). Twenty-nine per cent of patients with positive results had a personal history of AD in period A and 44% in period B (p = 0.015). Differences in the positivity of allergens between different time periods reflect changes in habits, of allergens exposure or preventive measures.

  1. Measurement of DNA-protein cross-links in human leukocytes following acute ingestion of chromium in drinking water.

    PubMed

    Kuykendall, J R; Kerger, B D; Jarvi, E J; Corbett, G E; Paustenbach, D J

    1996-09-01

    Increased DNA-protein cross-linking (DPX) in circulating leukocytes has been proposed as a potential biomarker for exposure and genotoxic damage caused by inhalation of certain reactive chemicals, such as hexavalent chromium [Cr(VI)]. This study was designed to determine whether ingestion of a single dose of potassium dichromate alone [Cr(VI)] or potassium dichromate fully reduced to Cr(III) with orange juice (prior to ingestion) causes an increase in DPX of circulating leukocytes in humans. Four adult male volunteers ingested a bolus dose of 5000 micro chromium in a 0.51 volume of water (10 p.p.m.), and blood samples were collected at 0, 60, 120, 180 and 240 min afterwards for analysis of DPX formation in circulating leukocytes. Results were compared to each person's own background concentration of DPX in leukocytes. Blood and urine samples were also collected for up to 2 weeks following the dose to examine the pattern of uptake and excretion of chromium. The results showed that there was no significant change in DPX observed following either Cr(VI) or Cr(III) ingestion, even though blood and urine chromium measurements indicated systemic uptake of a substantial fraction of the ingested chromium. Since Cr(III) does not possess DPX-inducing properties while Cr(VI) does, these results suggest that the Cr(VI) was reduced to Cr(III) intragastrically prior to absorption or that the amount of Cr(VI) absorbed into the blood was insufficient to produce DPX. These results are consistent with prior research that indicated that DPX would not occur following exposure to Cr(VI) except at very high doses.

  2. 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.

  3. 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

  4. Preservation of samples for dissolved mercury

    USGS Publications Warehouse

    Hamlin, S.N.

    1989-01-01

    Water samples for dissolved mercury requires special treatment because of the high chemical mobility and volatility of this element. Widespread use of mercury and its compounds has provided many avenues for contamination of water. Two laboratory tests were done to determine the relative permeabilities of glass and plastic sample bottles to mercury vapor. Plastic containers were confirmed to be quite permeable to airborne mercury, glass containers were virtually impermeable. Methods of preservation include the use of various combinations of acids, oxidants, and complexing agents. The combination of nitric acid and potassium dichromate successfully preserved mercury in a large variety of concentrations and dissolved forms. Because this acid-oxidant preservative acts as a sink for airborne mercury and plastic containers are permeable to mercury vapor, glass bottles are preferred for sample collection. To maintain a healthy work environment and minimize the potential for contamination of water samples, mercury and its compounds are isolated from the atmosphere while in storage. Concurrently, a program to monitor environmental levels of mercury vapor in areas of potential contamination is needed to define the extent of mercury contamination and to assess the effectiveness of mercury clean-up procedures.Water samples for dissolved mercury require special treatment because of the high chemical mobility and volatility of this element. Widespread use of mercury and its compounds has provided many avenues for contamination of water. Two laboratory tests were done to determine the relative permeabilities of glass and plastic sample bottles to mercury vapor. Plastic containers were confirmed to be quite permeable to airborne mercury, glass containers were virtually impermeable. Methods of preservation include the use of various combinations of acids, oxidants, and complexing agents. The combination of nitric acid and potassium dichromate successfully preserved mercury in a

  5. 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.

  6. Butylated hydroxytoluene does not protect Chinese hamster ovary cells from chromosomal damage induced by high-dose rate 192Ir irradiation.

    PubMed

    Grillo, C A; Dulout, F N

    2006-11-01

    Previous reports showed the protective effect of the synthetic antioxidant butylated hydroxytoluene (BHT) against the chromosomal damage induced by bleomycin (BLM), cadmium chloride and potassium dichromate. To test the hypothesis that this effect was exerted by inhibition and/or scavenging of reactive oxygen species (ROS), the effect of BHT on the chromosomal damage induced by a high dose-rate gamma rays (HDR (192)Ir). Experiments were carried out by irradiating G(1) CHO cells with nominal doses of 1, 2 or 3 Gy. BHT (doses of 1.0, 2.5 or 5.0 microg/ml) was added to the culture immediately before or immediately after irradiation. Cells were then incubated in the presence of BHT for 13 h until harvesting and fixation. Results obtained showed that BHT did not decrease the chromosomal damage induced by radiation in any consistent fashion. On the contrary, in cells post-treated with 5.0 microg/ml of BHT the yield of chromosomal aberrations increased in several experimental points. These results with ionizing radiation suggest that the previous observed protective effects of BHT on the chromosomal damage induced by chemical genotoxicants may not be mediated solely through the scavenging or inactivating reactive oxidative species. The decrease of the yield of chromosomal damage induced by BLM could be due to the union of BHT with a metallic ion, in this case Fe (II), required for the activation of BLM. In the same way, the protective effect of BHT on the chromosomal damage induced by cadmium chloride and potassium dichromate could be due to the decrease of the effective dose of both salts in the cell through the chelation of the cations by BHT.

  7. 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

  8. Assessment of exposure to alcohol vapor from alcohol-based hand rubs.

    PubMed

    Bessonneau, Vincent; Thomas, Olivier

    2012-03-01

    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 K(2)Cr(2)O(7) and H(2)SO(4). 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

  9. 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

  10. 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

  11. 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

  12. 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.

  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. Evolution of soil organic matter changes using pyrolysis and metabolic indices: a comparison between organic and mineral fertilization.

    PubMed

    Marinari, S; Masciandaro, G; Ceccanti, B; Grego, S

    2007-09-01

    The aim of this study was to evaluate chemical and biochemical changes of organic matter in fertilized (ammonium nitrate) and amended (vermicompost and manure) soils using pyrolysis and metabolic indices. The metabolic potential [dehydrogenase (DH-ase)/water soluble organic carbon (WSOC)], the metabolic quotient (qCO2) and the microbial quotient (Cmic:Corg) were calculated as indices of soil organic matter evolution. Pyrolysis-gas chromatography (Py-GC) was used to study structural changes in the organic matter. Carbon forms and microbial biomass have been measured by dichromate oxidation and fumigation-extraction methods, respectively. Dehydrogenase activity has been tested using INT (p-Iodonitrotetrazolium violet) as substrate. The results showed that organic amendment increased soil microbial biomass and its activity which were strictly related to pyrolytic mineralization and humification indices (N/O, B/E3). Mineral fertilization caused a greater alteration of native soil organic matter than the organic amendments, in that a high release of WSOC and relatively large amounts of aliphatic pyrolytic products, were observed. Therefore, the pyrolysis and metabolic indices provided similar and complementary information on soil organic matter changes after mineral and organic fertilization.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Automated amperometric plutonium assay system

    SciTech Connect

    Burt, M.C.

    1985-01-01

    The amperometric titration for plutonium assay has been used in the nuclear industry for over twenty years and has been in routine use at the Hanford Engineering Development Laboratory since 1976 for the analysis of plutonium oxide and mixed oxide fuel material for the Fast Flux Test Facility. It has proven itself to be an accurate and reliable method. The method may be used as a direct end point titration or an excess of titrant may be added and a back titration performed to aid in determination of the end point. Due to the slowness of the PuVI-FeII reaction it is difficult to recognize when the end point is being approached and is very time consuming if the current is allowed to decay to the residual value after each titrant addition. For this reason the back titration in which the rapid FeII-CrVI reaction occurs is used by most laboratories. The back titration is performed by the addition of excess ferrous solution followed by two measured aliquots of standard dichromate with measurement of cell current after each addition.

  2. Determination of mercury in geological materials by continuous-flow, cold-vapor, atomic absorption spectrophotometry

    SciTech Connect

    Kennedy, K.R.; Crock, J.G.

    1987-06-01

    To determine mercury in geological materials, samples are digested with nitric acid and sodium dichromate in a closed teflon vessel. After bringing to a constant weight, the digest is mixed with air and a sodium chloride-hydroxylamine hydrochloride-sulfuric acid solution and then Hg(II) is reduced to Hg/sup 0/ with stannous chloride in a continuous flow manifold. The mercury vapor is then separated and measured using cold vapor atomic absorption spectrophotometry (CV-AAS). For a 100 mg sample the limit of detection is 20 parts-per-billion (ppb) Hg in sample. To obtain a 1% absorption signal, the described method requires 0.21 ppb Hg solution (equal to 16 ppb in sample). Precision is acceptable at less than 1.2% RSD for a 10 ppb Hg aqueous standard. Accuracy is demonstrated by the results of the analysis on standard reference materials. Several elements do interfere but the effect is minimal because either the digestion procedure does not dissolve them (e.g., Au or Pt) or they are normally of low abundance (e.g., Se or Te).

  3. 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.

  4. 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.

  5. Synthesis, Characterization and Antitumor Activity of cis-bis(acylthioureato) platinum(II) Complexes, cis-[PtL2] [HL1=N,N-Diphenyl-N'-Benzoylthiourea or HL2=N,N-diphenyl-N'-(p-nitrobenzoyl)thiourea

    PubMed Central

    Hernández, Wilfredo; 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 1H NMR spectrum. At least two downfield shifted and broad paramagnetic signals were apparent in the 1H 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 1H-13C 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

  6. Cytoprotection against Cr(6+)-induced DNA damage by alpha-lipoic acid: implications in reducing occupational cancer risk.

    PubMed

    Kumar, Sushil; Budhwar, Roli; Nigam, Akanksha; Priya, Shivam

    2009-11-01

    Alpha-lipoic acid (LA), the metabolic antioxidant, was evaluated for its potential to protect against Cr(6+)-induced DNA damage. Potassium dichromate was administered to Swiss albino mice orally ad libitum at the doses of 5, 10 or 25 mg/kg body weight in drinking water to set DNA damage in cells, which was characterized in mouse peripheral blood mononuclear cells and bone marrow cells using single-cell gel electrophoresis and analyses of generated comets for Tail moment, Tail DNA and Tail length. DNA damage was dose dependent. Cytoprotection by LA was remarkable. LA (5, 10 and 25 mg/kg body weight intraperitoneally) in pre-, co- and post-toxicant administration schedule abrogated DNA damage substantially in both cell types. Protection by LA was also dose dependent. LA annulled DNA damage by Cr(6+) in plasmid relaxation assay. A negligible DNA damage resulted during interaction of Cr(6+) and LA. Compared to ascorbate, LA emerged as a better antioxidant and least DNA damaging. In conclusion, our study advocated an experimental therapeutic research potential in LA against Cr(6+)-induced DNA damage for reduction of occupational cancer risk in humans. PMID:19710206

  7. Developing ultrafast laser inscribed volume gratings

    NASA Astrophysics Data System (ADS)

    MacLachlan, David G.; Choudhury, Debaditya; Arriola, Alexander; Cunningham, Colin; Thomson, Robert R.; Kirkham, Andrew; Lee, David

    2014-07-01

    Due to their high efficiency and broad operational bandwidths, volume phase holographic gratings (VPHGs) are often the grating technology of choice for astronomical instruments, but current VPHGs exhibit a number of drawbacks including limits on their size, function and durability due to the manufacturing process. VPHGs are also generally made using a dichromated gelatine substrate, which exhibits reduced transmission at wavelengths longer than ~2.2 μm, limiting their ability to operate further into the mid-infrared. An emerging alternative method of manufacturing volume gratings is ultrafast laser inscription (ULI). This technique uses focused ultrashort laser pulses to induce a localised refractive index modification inside the bulk of a substrate material. We have recently demonstrated that ULI can be used to create volume gratings for operation in the visible, near-infrared and mid-infrared regions by inscribing volume gratings in a chalcogenide glass. The direct-write nature of ULI may then facilitate the fabrication of gratings which are not restricted in terms of their size and grating profile, as is currently the case with gelatine based VPHGs. In this paper, we present our work on the manufacture of volume gratings in gallium lanthanum sulphide (GLS) chalcogenide glass. The gratings are aimed at efficient operation at wavelengths around 1 μm, and the effect of applying an anti-reflection coating to the substrate to reduce Fresnel reflections is studied.

  8. Holographic optical coupling and beamsplitting elements for optoelectronic interconnects and sensors

    NASA Astrophysics Data System (ADS)

    Schmidt, Juerg; Voelkel, Reinhard; Rosner, S.; Stork, Wilhelm; Sheridan, John T.; Durst, Franz; Schwider, Johannes; Streibl, Norbert

    1993-01-01

    Holographic optical elements (HOEs) are compact and flexible in their function: they can integrate focussing deflection and beamsplitting into a single element. Optical systems consisting of several elements can be built by recording planar HOEs side by side onto a common planar substrate -- a light guiding plate. By folding the light path, i.e., using multiple reflections within this plate, the light is guided from one HOE to the other. This concept is investigated for two applications: (1) An optoelectronic board to board interconnection based on holographic coupling elements on a light guiding plate: Diode lasers and pin diodes were used as optoelectronic transmitters at a data rate of 500 MBits/s. The coupling elements were volume gratings, recorded in dichromated gelatine (DCG) and coated onto the surface of the light guiding plate. Inside the plate the light was guided by total internal reflection. An overall loss of this transmission system of -2.6 dB over a distance of 11 cm was observed. (2) A miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry (LDV): HOEs mounted onto a glass substrate are used for beamsplitting and deflection. Volume holograms in DCG exhibit good optical efficiency (75% transmission of a cascade of two HOEs). In contrast to conventional sensor heads with diffractive devices one can achieve achromatic behavior which makes the sensor insensitive against wavelength drifts or mode hopping of a semiconductor laser.

  9. Phase-diffractive coating for daylight control on smart window

    NASA Astrophysics Data System (ADS)

    Perennes, Frederic; Twardowski, Patrice J.; Gesbert, D.; Meyrueis, Patrick

    1992-11-01

    Daylight can be processed by a smart window in a transmission, reflective, refractive, and diffractive mode. In the future an optimization will be realized by a mixing of these approaches depending on the applied cases. Non-imaging diffractive optics has its roots in the work done in holographic diffractive coating for head up displays (HUD) and helmet mounted displays. For having globally good results on smart window with diffractive coating, a very high diffraction efficiency must be reached close to 100% without having a too important lowering of the control of other parameters of the light processed by a smart window (direction and frequency control essentially). We propose a method for designing, realizing, and using diffractive coating for a smart window that is based on a new organic material and diffractive model that were already validated in HUD. Potential low cost is possible for mass production on a large surface with an adapted investment. We describe the present technology and its limits and the ones that can be reached in the future. In this work, we present a holographic way to modify the slant of sun rays through a window, and to filter infrared radiations by using dichromated gelatin material. In this way it would be able to ensure a more uniform lighting and a more pleasant temperature inside buildings or vehicles, without using dye or photochromics glasses.

  10. Polarization properties of gelatin holograms

    NASA Astrophysics Data System (ADS)

    Rallison, Richard D.; Schicker, Scott R.

    1992-05-01

    Dichromated gelatin exhibits variable changes in effective refractive index (n) from 1.54 before exposure to less than 1.25 as it expands during processing. This aerogel like effects causes aberrations in diffractive optics and Kogelnik's theory predicts strong polarization separation in gratings at many different angles other than 90 degrees. The diffraction efficiency of both S and P polarizations at any angle is dependent on the product of thickness and index modulation while the angle inside the medium is dependent on n. We investigated predicted conditions where only one polarization would be diffracted and subsequently proved n varies from about 1.4 to 1.2 after processing and depends on the film thickness and processing procedures. Transmission gratings made at angles from 36 to 66 degrees were fit to mathematical models as proof of the phenomena, some performed with extinction ratios greater than 100:1. We were also able to demonstrate a similar range in conformal reflection structures and to design a novel polarizer. The calculation of exposure geometries for display holograms becomes more accurate when index change is included in the formulas but some results remain hard to explain.

  11. 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.

  12. Spectrophotometric determination of certain cephalosporins in pure form and in pharmaceutical formulations

    NASA Astrophysics Data System (ADS)

    Amin, Alaa S.; Ragab, Gamal H.

    2004-10-01

    A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 μg ml -1 at λmax 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 μg ml -1. The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient ≤0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods.

  13. 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.

  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. Effect of acute hexavalent chromium exposure on pituitary-thyroid axis of a freshwater fish, Channa punctatus (Bloch).

    PubMed

    Mishra, Ashish K; Mohanty, Banalata

    2015-01-01

    Acute exposure to hexavalent chromium (10 mg L(-1) , 20 mg L(-1) , and 40 mg L(-1) potassium dichromate for 96 h) dose-dependently affected the pituitary-thyroid axis of teleost, Channa punctatus. Significant hypertrophy of the thyroid follicle was observed in 20 mg L(-1) and 40 mg L(-1) groups; the follicular epithelium was however hypertrophied only in 40 mg L(-1) group. The colloid depletion in the lumen of thyroid follicle was evident in 20 mg L(-1) and 40 mg L(-1) groups. Serum thyroid hormones (thyroxine/T4 and triiodothyronine/T3) level increased significantly at both the higher doses. Increased immunointensity and significant hypertrophy of the pituitary thyrotrophs (anti TSHβ-immunoreactive cells) was observed in both 20 mg L(-1) and 40 mg L(-1) chromium-exposed fish. The increased thyroid hormones secretion observed in this study might be an adaptive response of the pituitary-thyroid axis under acute chromium-induced stress condition to maintain homeostasis. The long-term Cr(VI) exposures, however, may lead to attenuation/exhaustion of the pituitary-thyroid axis and pose serious threat to fish health and affect their population.

  16. Changes in chromium distribution during the electrodialytic remediation of a Cr (VI)-contaminated soil.

    PubMed

    Nieto Castillo, Ana M; Soriano, Juan José; García-Delgado, Rafael A

    2008-04-01

    A laboratory study has been carried out to determine the feasibility of in situ remediation of chromium (VI)-contaminated soil using electrodialysis in relation to its speciation in soil. This technique is best suited for low-permeability soils or sediments, which may be difficult to remediate by other means and implies the application of a low-intensity direct current to the soil, which is separated from the electrode compartments by ion-exchange membranes. A clayey soil was prepared for use in the experiments and was characterized before being mixed with a solution of potassium dichromate for several days to produce a final Cr content of 4,056 mg/kg of soil dry wt. Remediation tests were carried out under constant-voltage conditions for periods of 7-14 days and the evolution of applied current to the cell, pH, and conductivity of the electrolytes were recorded periodically. Fractionation of chromium was determined for soil samples before and after remediation using a standardized four-step sequential extraction procedure (SEP) with acetic acid, hydroxylamine, hydrogen peroxide, and aqua regia solutions. Results show that chromium is mobilized from the most labile phases (soluble/exchangeable/carbonate). In a 15 V test, SEP results show that the amount of chromium extracted in the first step drops from 80% to 9%, but also that changes in the total chromium distribution occur during the treatment with some transferred to other soil phases that are more difficult to mobilize.

  17. Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

    PubMed Central

    Ding, Yuanzhao; Peng, Ni; Du, Yonghua; Ji, Lianghui

    2014-01-01

    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 (Cr2O72−), 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

  18. Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides)--an in vitro study.

    PubMed

    Geetha, S; Sai Ram, M; Singh, V; Ilavazhagan, G; Sawhney, R C

    2002-03-01

    This study was designed to determine the anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) using lymphocytes as a model system. Chromium(VI) as potassium dichromate was used to induce oxidative damage. The production of free radicals by chromium and the ability of alcoholic leaf and fruit extracts of seabuckthorn to inhibit the oxidative damage induced by chromium was investigated. Addition of chromium (10 microg/ml) to the cells resulted in enhanced cytotoxicity, apoptosis, free radical production and decreased glutathione (reduced) levels. Chromium also caused a significant inhibition of lymphocyte proliferation induced by both lipopolysaccharide and concanavalin A. Alcoholic extracts of leaves and fruits of seabuckthorn at a concentration of 500 microg/ml were found to inhibit chromium-induced free radical production, apoptosis, DNA fragmentation and restored the anti-oxidant status to that of control cells. In addition, these extracts also were able to arrest the chromium-induced inhibition of lymphocyte proliferation. These observations suggest that the alcoholic extracts of leaves and fruits of seabuckthorn have marked cytoprotective properties, which could be attributed to the anti-oxidant activity. PMID:11849845

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

    PubMed

    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.

  20. 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.

  1. A facile synthesis-fabrication strategy for integration of catalytically active viral-palladium nanostructures into polymeric hydrogel microparticles via replica molding.

    PubMed

    Yang, Cuixian; Choi, Chang-Hyung; Lee, Chang-Soo; Yi, Hyunmin

    2013-06-25

    The synthesis of small, uniform, well-dispersed and active Pd nanocatalysts under mild conditions in a predictable and controlled manner is an unmet challenge. Viral nanomaterials are attractive biotemplates for the controlled synthesis of nanoparticles due to their well-defined and monodisperse structure along with abundant surface functionalities. Here, we demonstrate spontaneous formation of small (1-2 nm), uniform and highly crystalline palladium (Pd) nanoparticles along genetically modified tobacco mosaic virus (TMV1cys) biotemplates without external reducing agents. The ratio between TMV and Pd precursor plays an important role in the exclusive formation of well-dispersed Pd nanoparticles along TMV biotemplates. The as-prepared Pd-TMV complexes are then integrated into the poly(ethylene glycol) (PEG)-based microparticles via replica molding (RM) technique in a simple, robust and highly reproducible manner. High catalytic activity, recyclability and stability of the hybrid Pd-TMV-PEG microparticles are further demonstrated through dichromate reduction as a model reaction. Taken together, these findings demonstrate a significant step toward simple, robust, and scalable synthesis and fabrication of efficient biotemplate-supported Pd nanocatalysts in readily deployable polymeric scaffolds with high capacity in a controlled manner.

  2. Influence of irritants on lymph node cell proliferation and the detection of contact sensitivity to metal salts in the murine local lymph node assay.

    PubMed

    Ikarashi, Y; Tsukamoto, Y; Tsuchiya, T; Nakamura, A

    1993-09-01

    Dimethyl sulfoxide (DMSO) and sodium lauryl sulfate (SLS) are known to cause irritation of the skin, and to enhance the penetration of chemicals into the epidermis. In the present study, the lymph node cell (LNC) proliferative response following exposure to irritants, such as SLS and DMSO, was examined in the murine local lymph node assay (LLNA). Exposure to DMSO or SLS aqueous solution induced a small increase in lymph node cell proliferation compared with aqueous solution alone. Exposure to SLS in DMSO caused a significant increase in LNC proliferation. Further, the effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was examined. Application of potassium dichromate and nickel sulfate in DMSO or SLS aqueous solution caused increases in LNC proliferation. Exposure to metal allergen with SLS in DMSO also induced a significant LNC proliferative response, but did not induce a significant increase in stimulation index (increase in 3H-thymidine incorporation relative to vehicle-treated control group). This was because of increased 3H-thymidine incorporation following exposure to SLS-DMSO in the control group. These results suggest that irritants enhance the LNC proliferative responses to metal allergens. The use of SLS in aqueous solution is effective for the detection of sensitivity to water-soluble allergens, such as metal allergens, in the LLNA, as well as the use of DMSO as an application vehicle.

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Patch test results in schoolchildren. Results from the Information Network of Departments of Dermatology (IVDK) and the German Contact Dermatitis Research Group (DKG)

    PubMed

    Brasch, J; Geier, J

    1997-12-01

    Our aim was to explore the current spectrum of contact allergens in schoolchildren, as a basis for diagnosis and prevention of allergic contact dermatitis. Results of patch tests in children 6-15 years old, performed in the years 1990-1995 by 22 centres of the German Contact Dermatitis Research Group and filed by the Information Network of Departments of Dermatology, were analysed and evaluated retrospectively, including epidemiologic data. Children with positive tests (62 out of 156 boys and 108 out of 260 girls tested) had a higher frequency of allergic contact dermatitis and a lower frequency of atopic dermatitis than patch test negative ones. 16 distinct allergens elicited positive reactions in > or = 1% of the children tested. Reactions to nickel sulfate occurred in 15.9% of all children tested, but in 25.0% of girls 14/15 years old, and in only 4.5% of boys 6-13 years old. Double-sensitizations with cobalt salts, potassium dichromate and palladium were seen. Mercury compounds were found in 2nd place (thimerosal: all children: 11.3%; 6-13 years old: 14.3%; 14/15 years old: 8.0%), followed by fragrance allergens. We conclude that contact allergy in children is related to their sex and age. Prophylaxis against nickel, mercury, and fragrance allergy needs to be improved. A shortened standard series may be sufficient for testing children.

  8. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    PubMed

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm. PMID:27661578

  9. 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

  10. 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.

  11. 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.

  12. Preliminary study on the use of a Teladorsagia circumcincta bulk milk ELISA test in dairy goats under experimental conditions.

    PubMed

    Molina, J M; Hernández, Y; Ruiz, A; González, J F; Argüello, A; Ferrer, O; Forbes, A B

    2009-12-23

    An ELISA test for the detection of anti-Teladorsagia circumcincta antibodies in goat milk samples (both individual and bulk milk samples) has been developed in dairy goats experimentally infected with a trickle infection. The results observed were compared with those obtained when some other standard methods for the detection of animals infected with gastrointestinal nematodes (GIN), such as faecal egg counts (FEC) and serum pepsinogen levels. Some factors that could affect the final results of the test (dilution and nature of samples as well as their preservation at 4 degrees C for 0-10 days) were also monitored. The results show that the proposed test could allow the detection of infected herds using bulk milk samples. The levels of anti-T. circumcincta antibodies in milk and serum samples and the concentrations of serum pepsinogen showed a similar pattern over time. Refrigeration of milk samples for less than 5 days or its preservation with potassium dichromate for 10 days did not significantly affect the ability of the test to detect infected animals. Finally, when a commercial Ostertagia ostertagi ELISA kit was used to assay milk samples from goats infected with T. circumcincta, the results suggest that it may be possible to use a crude O. ostertagi antigen-based ELISA for the detection of goats infected with T. circumcincta.

  13. Observations on the contrasting reaction of some electron dense stains applied on epoxy-embedded tissue sections.

    PubMed

    Tato, A; Ferrer, J M; Quintana, E; Romero, J B; Del Castillo, P; Stockert, J C

    1990-01-01

    Epon sections from glutaraldehyde-fixed rat bone marrow were treated with aqueous solutions of the following electron contrasting agents: uranyl acetate, ruthenium red, potassium permanganate, potassium dichromate, stannous chloride, palladium (II) chloride, sodium molybdate, phosphomolybdic acid, molybdenum heteropolyblue, phosphotungstic acid, iron(II)-phenanthroline, aluminium-hematoxylin, mercurochrome, cuprolinic blue, and sirius light turquoise blue. At the ultrastructural level, a high degree of electron opacity was always observed in mast cell granules and the crystalline inclusion (internum) of eosinophil granules. The chromatin revealed a somewhat lower and variable contrasting reaction, while the matrix (externum) of eosinophil granules appeared with scarce or no contrast. This pattern of electron opacity showed no correlation with the type of agent used; therefore, it can be assumed that binding processes based on the own chemical reactivity of the compounds are rather of secondary importance. The differential epoxy resin embedding of cell structures and the variable access of aqueous reagents through the non-polar plastic could be the predominant factors which account for these contrasting reactions.

  14. 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.

  15. 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.

  16. 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

  17. Isolation of Toxoplasma gondii from horse meat in Egypt.

    PubMed

    Shaapan, R M; Ghazy, A A

    2007-01-01

    Portions of heart, liver, skeletal and diaphragmatic muscles obtained from 150 slaughtered horses at Giza-Zoo abattoir were used for bioassays in mice and cats. T. gondii tachyzoites were isolated successfully from the peritoneal exudates of the inoculated mice 6-8 days post inoculation with pooled horse tissues. Whereas, T. gondii tissue cysts containing bradyzoites were detected in the impression smears of mice brain on the 45th days or more post infection. The oocysts were detected in feces of cats 3-6 days post feeding on horse tissues containing tissue cysts. The oocysts became sporulated within 3-5 days in 2.5% Potassium dichromate. A total of 79 out of 150 horse meat samples were found to be infected with an incidence rate of 52.6 %. This is the first trial for isolation of T. gondii infective stages from horses in Egypt. Moreover, this study pointed out to the high infection rate of T. gondii in horse meat which may be considered as an important source of infection to wild zoo-animals in Egypt and humans in some countries if consumed raw or insufficiently cooked.

  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. 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

  20. 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

  1. Role of Carum copticum seeds in modulating chromium-induced toxicity on human bronchial epithelial cells and human peripheral blood lymphocytes.

    PubMed

    Deb, Dipanwita Dutta; Parimala, G; Devi, S Saravana; Chakrabarti, T

    2012-11-01

    Carum copticum seeds are well known for ailment of various diseases since ancient times. The present study pertains to investigate modulatory effects of methanolic extract of C. copticum seeds (MCE) against hexavalent chromium induced cytotoxicity, genotoxicity, apoptosis and oxidative stress on human bronchial epithelial cells (BEAS-2B) and isolated human peripheral blood lymphocyte (PBL) in vitro. Treatment of BEAS-2B and PBL with MCE prior to potassium dichromate (K(2)Cr(2)O(7)) treatment exhibited an increase in cell viability and decrease of DNA damage as compared to K(2)Cr(2)O(7) treatment alone, as evaluated by WST-8 and Comet assay respectively. Further, MCE administration 1h prior to graded doses of K(2)Cr(2)O(7) significantly decreased reactive oxygen species (ROS) level, increased the mitochondrial membrane potential, reduced apoptosis and caspase 3 activity. MCE also ameliorated K(2)Cr(2)O(7) induced decrease in superoxide dismutase (SOD), glutathione peroxidase (GPx) antioxidant enzyme levels in BEAS-2B and PBL cells accompanied by reduction in lipid peroxides with maximum effect at 50 μg/ml. Thus, this study provides strong evidence to support the beneficial effect of MCE in preventing Cr(VI) induced toxicity in BEAS-2B and PBL cells.

  2. Long-Term Methadone Intake and Genotoxicity in Addicted Patients

    PubMed Central

    Rezaei, Mohsen; Khodaei, Forouzan; Sayah Bargard, Mehdi; Abasinia, Mahsa

    2015-01-01

    Background: It is well known that contact with some physical, chemical or biological compounds can increase the incidence of mutation. Among these compounds, are pharmaceuticals that meet long duration of use and potentially could be misused and taken more than the ordered dosage. Objectives: The aim of this study was to evaluate mutagenic effect of methadone in addicted patients referred to Imam Khomeini Hospital in Ahvaz by single cell gel electrophoresis technic or comet assay. Patients and Methods: In this study, 90 subjects were divided into dichromate treated group, no treated healthy volunteers group and test group. Each group included 30 subjects. Screening was performed according to questionnaire and qualified subjects were entered the study. Blood samples were collected and lymphocytes were isolated, mixed with low melting point agarose for slide preparation according to standard method. Slides were analyzed using fluorescence microscope and comet patterns were assessed. Results: The mutagenicity index in addicted group was robustly higher than healthy volunteers. Fortunately, this significant difference was lower than positive control. Conclusions: Genome instability in addicted patients was demonstrated in this study. Controversially, considering incoherent results of previous studies and our data, more studies in longer duration of methadone use are needed to elucidate the consequence. PMID:25866713

  3. Validation test with embryonic and larval stages of Chordodes nobilii (Gordiida, Nematomorpha): sensitivity to three reference toxicants.

    PubMed

    Achiorno, Cecilia L; de Villalobos, Cristina; Ferrari, Lucrecia

    2010-09-01

    Chordodes nobilii is a parasite whose pre- and postparasitic stages are found in different types of freshwater bodies. Due to the peculiarities of its life cycle, it acts as a link between freshwater bodies and terrestrial ecosystems. There is little toxicological information on the group Gordiida. It is only known that embryos and larvae of C. nobilii are sensitive to glyphosate and malathion at relevant concentrations in the environment. On this basis, the aims of this study were to characterize the sensitivity of the pre-parasitic stages of C. nobilii to three reference toxicants: sodium dodecyl sulfate (SDS), cadmium chloride and potassium dichromate (Cr(6+)), and to validate a previous experimental protocol for ecotoxicological risk assessment. The protocol involved acute exposure of early embryonic stages and larvae to the three toxicants for 96 h and 48 h, respectively. Embryo development was inhibited only by Cr(6+) which presented a IC(50) of 0.71 mg Cr(6+)L(-1). The development of the eggs exposed to SDS and those exposed to cadmium chloride showed no differences as compared to that of controls. However, the infective capacity of larvae derived from the eggs exposed to the three toxicants was lower than that of controls. Larval survival was affected even at the lowest concentration of the three toxicants assayed. In relation to other freshwater organisms, C. nobilii can be characterized as an organism medium to highly sensitive to the toxicants tested.

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  6. Exposure to sublethal chromium and endosulfan alter the diel vertical migration (DVM) in freshwater zooplankton crustaceans.

    PubMed

    Gutierrez, María Florencia; Gagneten, Ana María; Paggi, Juan Cesar

    2012-01-01

    Among zooplankton behaviors, diel migrations constitute one of the most effective predator avoidance strategy and confer metabolic and demographic advantages. We aim to examine whether sublethal concentrations of two widespread pollutants (a pesticide with endosulfan and chromium as potassium dichromate) alter the depth selection, vertical migration and grouping of five freshwater species: Argyrodiaptomus falcifer, Notodiaptomus conifer, Pseudosida variabilis, Ceriodaphnia dubia and Daphnia magna. In a series of experimental assays, performed with 150 cm length transparent tubes, we analyzed the ascents and descents movements through periods of 24 h. Among controls, the copepods showed a tendency to remain closest to the surface, however, N. conifer registered a downward movement of 18.14 cm between 06:00 and 12:00. The cladoceran P. variabilis occupied the deeper position (85 cm), C. dubia showed a tendency to hike to the surface at 06:00 (57.7 cm) descending to lower levels at 18:00. D. magna showed a constant movement of ascent between 00:00 and 18:00, making an average travel of 29.4 cm. When subjected to pollutants, these behaviors were altered. It is hypothesized that a reduction in swimming activity and disorientation would be the main cause of such alterations. The high sensitivity of this endpoint sugests it to be adecuate as a complement in future standard toxicity tests.

  7. 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 %.

  8. 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

  9. 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.

  10. Contamination of public parks and squares from Guarulhos (São Paulo State, Brazil ) by Toxocara spp. and Ancylostoma spp.

    PubMed

    Marques, Jacó Pereira; Guimarães, Catarina de Rezende; Boas, Ailton Vilas; Carnaúba, Paulo Usignolo; Moraes, Josué de

    2012-01-01

    The contaminated soil with mammal feces is an important factor of risk to infection with zoonotic diseases. Amongst these zoonoses are visceral larva migrans and cutaneous larva migrans caused by Toxocara spp. and Ancylostoma spp., respectively. The aim of this study was to assess the environmental contamination by Toxocara spp. eggs and hookworms (Ancylostoma spp.) in public parks and squares in the city of Guarulhos, a metropolitan area of São Paulo, São Paulo State, Brazil. Soil samples were collected, between September and December 2010, and examined using the centrifugal flotation technique with sodium dichromate and zinc sulphate as well as the modified Baermann method. Notably, 35 (74.5%) of the 47 districts surveyed in Guarulhos possessed samples contaminated with Toxocara spp. and/or eggs or larvae of Ancylostoma spp. The frequency of Toxocara spp. and Ancylostoma spp. in the samples from public areas was 68.1% and 46.8%, respectively. Overall, the eastern side of Guarulhos is the region with the highest occurrence of causative agents of larva migrans. In all collection sites, the presence of feces from dogs and cats accompanied by their owners and stray animals were observed. Notably, it is important to adopt measures to control dog and cat breeding, to treat infected animals, and provide health education to the population.

  11. Replication of cultured lung epithelial cells

    SciTech Connect

    Guzowski, D.; Bienkowski, R.

    1986-03-05

    The authors have investigated the conditions necessary to support replication of lung type 2 epithelial cells in culture. Cells were isolated from mature fetal rabbit lungs (29d gestation) and cultured on feeder layers of mitotically inactivated 3T3 fibroblasts. The epithelial nature of the cells was demonstrated by indirect immunofluorescent staining for keratin and by polyacid dichrome stain. Ultrastructural examination during the first week showed that the cells contained myofilaments, microvilli and lamellar bodies (markers for type 2 cells). The following changes were observed after the first week: increase in cell size; loss of lamellar bodies and appearance of multivesicular bodies; increase in rough endoplasmic reticulum and golgi; increase in tonafilaments and well-defined junctions. General cell morphology was good for up to 10 wk. Cells cultured on plastic surface degenerated after 1 wk. Cell replication was assayed by autoradiography of cultures exposed to (/sup 3/H)-thymidine and by direct cell counts. The cells did not replicate during the first week; however, between 2-10 wk the cells incorporated the label and went through approximately 6 population doublings. They have demonstrated that lung alveolar epithelial cells can replicate in culture if they are maintained on an appropriate substrate. The coincidence of ability to replicate and loss of markers for differentiation may reflect the dichotomy between growth and differentiation commonly observed in developing systems.

  12. Excess chromium alters uptake and translocation of certain nutrients in citrullus.

    PubMed

    Dube, B K; Tewari, Kamlesh; Chatterjee, J; Chatterjee, C

    2003-12-01

    Citrullus plants were grown in refined sand with varying levels of chromium to determine their tolerance limit to excess chromium. The plants were maintained in control nutrient solution for 24 days and on the 25th day chromium as dichromate was added at 0.05, 0.1, 0.2, 0.3 and 0.4 mM. A control set of plants was grown in the same nutrient solution without chromium. At chromium levels >0.2 mM plants showed growth depression, with chlorosis and loss of turgor of middle leaves. Affected leaves had narrow lamina; tendrils were thin, short and did not have coiling property. Later chlorosis became severe and changed to necrosis in patches. Petiole along with lamina became wilted, rugged and hung down due to complete loss of water. At lower chromium concentration, (0.05, 0.1 and 0.2 mM) only depression in growth was observed. With increase in chromium concentration of nutrient solution accumulation of chromium in different parts of Citrullus was increased. Increase in concentrations of phosphorus, manganese and decrease in iron, copper, zinc and sulphur were observed in leaves. Toxicity of chromium was greater at 0.2-0.4 mM, compared to lower concentrations. Threshold of toxicity and toxicity of Cr in old leaves were, respectively, 0.9 and 3.9 microg g(-1) dry matter of citrullus.

  13. 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).

  14. 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.

  15. Effect of V addition to Al and Al grain refined by Ti on chemical corrosion rates in NaOH solution with and without inhibitor at different temperatures

    NASA Astrophysics Data System (ADS)

    Zaid, Adnan I. O.; Al-Haj-Ali, Ahmad M.; Allawi, G. T. A.

    2014-06-01

    The paper presents the effect of vanadium addition to aluminum grain refined by titanium, in the range from 0.005 wt % to 0.236 wt %, on corrosion rate of these micro alloys in caustic soda (NaOH) solution at different temperatures. The corrosion rate decreased by the addition of any percent of vanadium at 25°C compared to pure Al. The corrosion rate increased with increase of solution temperature from 25 to 40 and 60 °C at any percent of vanadium addition. However, addition of vanadium reduced the corrosion rate at these temperatures at most wt.% of V addition. The maximum achieved reduction in corrosion rate due to vanadium addition was 40 % at 0.148 wt % and 60°C. The addition of 3 % potassium dichromate as corrosion inhibitor to NaOH solution reduced the average corrosion rates at any wt.% of vanadium. The inhibition efficiency ranged from 44- 58% at 25 °C and from 97-99% at 40 and 60°C.

  16. Surface preparation of polyolefins prior to adhesive bonding

    SciTech Connect

    Rosty, R.; Martinelli, D.; Devine, A.; Bodnar, M.J.; Beetle, J.

    1987-08-01

    The standard polyolefin surface treatment for adhesive bonding specifies using a potassium dichromate/sulfuric acid/water solution. This solution is both carcinogenic and polluting due to chromate inclusion. A study was made of the treated surface of polyolefin versus a control (untreated) surface in an attempt to find an alternate chemical polyolefin pretreatment for adhesive bonding. The new pretreatment solution would have to be noncarcinogenic and nonpolluting. Scanning electron microscope photos of a polyethylene surface treated in the standard solution show pitting not seen in the controls, similar to the P2 etch effect on aluminum surfaces. This pitting roughens the surface and leaves a larger surface area for adhesive bonding, suggesting one of the reasons this pretreatment yielded such good bond strengths. Another reason may be because it is an oxidant. Many nonchromate-bearing alternative solutions were tested. A good number of these were oxidizing agents, patterning the standard solution. Several test solutions resulted in bond strengths close in magnitude to those resulting from standard solution usage. 7 references.

  17. 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.

  18. Effects of temperature and different food matrices on Cyclospora cayetanensis oocyst sporulation.

    PubMed

    Sathyanarayanan, Lakshmi; Ortega, Ynes

    2006-04-01

    Effects of temperature on the sporulation of the parasite Cyclospora cayetanensis were studied in 2 food substrates, dairy and basil. Unsporulated Cyclospora oocysts were subjected to freezing and heating conditions for time periods ranging from 15 min to 1 wk. Oocysts were then removed from the food substrates and placed in 2.5% potassium dichromate for 2 wk to allow viable unsporulated oocysts to differentiate and fully sporulate, and to determine the percentage sporulation as an indicator of viability. Sporulation occurred when oocysts resuspended in dairy substrates were stored within 24 hr at -15 C. When oocysts were placed in water or basil, sporulation occurred after incubation for up to 2 days at -20 C, and up to 4 days at 37 C. Few oocysts sporulated when incubated for 1 hr at 50 C. Sporulation was not observed in basil leaves or water at -70 C, 70 C, and 100 C. Sporulation was not affected when incubated at 4 C and 23 C for up to 1 wk, which was the duration of the experiment in both of the tested substrates.

  19. 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).

  20. 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.

  1. Determination of mercury in rice by MSFIA and cold vapour atomic fluorescence spectrometry.

    PubMed

    da Silva, Douglas G; Portugal, Lindomar A; Serra, Antonio M; Ferreira, Sergio L C; Cerdà, Victor

    2013-04-15

    In the present paper the use of a MSFIA system for determination of mercury in rice by cold vapour atomic fluorescence spectrometry (CV AFS) is proposed. The sample digestion is performed in a microwave oven using nitric acid and hydrogen peroxide. The experimental conditions for vapour generation were determined using a full two-level factorial design involving the following factors: nitric acid and tin chloride concentrations and sample flow rate. Employing the conditions optimised, the method allows the determination of mercury using the external calibration technique with aqueous standards. The reached limits of detection and quantification were 0.48 and 1.61 ng g⁻¹ respectively, and the precision (as relative standard deviation) was 3.28% and 1.56% for rice samples with a mercury content of 3.63 and 5.81 ng g⁻¹, respectively. The method accuracy was confirmed analysing a certified reference material of rice flour furnished by National Institute of Standard and Technology. The interference of nitrous acid and nitrous oxides are removed using potassium dichromate. The method was applied to mercury determination in twelve rice samples acquired in Palma de Mallorca (Spain) between the months of January and April of 2012. The mercury content found varied from 2.15 to 7.25 ng g⁻¹. These results agree with those reported by others authors.

  2. 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

  3. Effects of temperature and different food matrices on Cyclospora cayetanensis oocyst sporulation.

    PubMed

    Sathyanarayanan, Lakshmi; Ortega, Ynes

    2006-04-01

    Effects of temperature on the sporulation of the parasite Cyclospora cayetanensis were studied in 2 food substrates, dairy and basil. Unsporulated Cyclospora oocysts were subjected to freezing and heating conditions for time periods ranging from 15 min to 1 wk. Oocysts were then removed from the food substrates and placed in 2.5% potassium dichromate for 2 wk to allow viable unsporulated oocysts to differentiate and fully sporulate, and to determine the percentage sporulation as an indicator of viability. Sporulation occurred when oocysts resuspended in dairy substrates were stored within 24 hr at -15 C. When oocysts were placed in water or basil, sporulation occurred after incubation for up to 2 days at -20 C, and up to 4 days at 37 C. Few oocysts sporulated when incubated for 1 hr at 50 C. Sporulation was not observed in basil leaves or water at -70 C, 70 C, and 100 C. Sporulation was not affected when incubated at 4 C and 23 C for up to 1 wk, which was the duration of the experiment in both of the tested substrates. PMID:16729675

  4. 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

  5. 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

  6. Thermostable lipase from Geobacillus sp. Iso5: bioseparation, characterization and native structural studies.

    PubMed

    Mahadevan, Gurumurthy D; Neelagund, Shivayogeeswar E

    2014-05-01

    The extracellular thermoalkaline lipase from Geobacillus sp. Iso5 was purified to homogeneity by ultrafiltration, 6% cross-linked agarose and Phenyl spehrose HIC column chromatography. The final purified lipase resulted in 8.7-fold with 6.2% yield. The relative molecular weight of the enzyme was determined to be a monomer of 47 kDa by SDS-PAGE and MALDI-TOF MS/MS spectroscopy. The purified enzyme exhibit optimum activity at 70 °C and pH 8.0. The enzyme retained above 90% activity at temperatures of 70 °C and about 35% activity at 85 °C for 2 h. However, the stability of the enzyme decreased at the temperature over 90 °C. The enzyme activity was promoted in the presence of Ca(2+) and Mg(2+) and strongly inhibited by HgCl2 , PMSF, DTT, K(+) , Co(2+) , and Zn (2+) . EDTA did not affect the enzyme activity. The secondary structure of purified lipase contains 36% α-helix and 64% β-sheet which was determined by Circular dichromism, FTIR, and Raman Spectroscopy.

  7. 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.

  8. Polarization gratings with surface relief in dyed gelatin and their postdevelopment diffraction

    NASA Astrophysics Data System (ADS)

    Martinez-Ponce, Geminiano; Solano, Cristina

    2002-04-01

    Some characteristics of dyed gelatin films when polarization gratings are recorded are reported. Two dyes, Malachite Green and Methylene Blue, are used in our experiment. In particular, no dichromate was added to Methylene Blue plates before or after exposure. It is shown that, in spite of its having high viscosity, a relief grating is formed when orthogonal linearly polarized beams are superimposed upon the plates. In contrast with previous observations in another photoanisotropic medium, the frequency of the gelatin relief grating does not depend on the directions of the electric field of the orthogonal recording beams. Besides, when orthogonal circularly polarized beams are used in the formation of polarization gratings, no relief grating is produced. Finally, we study the phase modulation obtained after dehydration of the gelatin plates in which the polarization gratings were formed. Postdevelopment phase gratings do not preserve the polarization information of the interference pattern. Also, the grating frequency is increased by a factor of 2 for linear polarization, whereas for circular polarization there is no phase modulation.

  9. 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

  10. 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

  11. Novel Aspects of Holographic Technologies and Applications Based on New Stationary and Dynamic Holographic Recording Media

    NASA Astrophysics Data System (ADS)

    Semenova, Irina

    2002-06-01

    This report results from a contract tasking of the Ioffe Institute as follows: Historically Russian holographic research laboratories developed many unique materials having no analogs in other countries. This effort leverages that expertise and investigates two aspects related to correction of distortion of laser communications signals: 1. Development of the technique for compensation of atmospheric distortions in laser communication systems by means of dynamic holograms. We expect that depending upon the chosen holographic medium the following operational characteristics are attainable: Duration of a write/read/erase cycle - 1.0 msecond; Quality of correction - 80%; Improvement of the signal to noise ratio - 90%. The device will be automatic, real-time and reliable. 2. Development of a new holographic material based on self-developing dichromated colloids, for recording of stationary volume holograms. This task will include measurement of the optical effects caused by photo induced structural changes and hopes to achieve a resolution of up to 5000 l/mm and sensitivity down to 100 mJ/cm2.

  12. 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

  13. 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.

  14. Effect of chemical stress and ultraviolet radiation in the bacterial communities of zebrafish embryos.

    PubMed

    Oliveira, Jacinta M M; Almeida, Ana Rita; Pimentel, Tânia; Andrade, Thayres S; Henriques, Jorge F; Soares, Amadeu M V M; Loureiro, Susana; Gomes, Newton C M; Domingues, Inês

    2016-01-01

    This study aimed to assess the effect of ultraviolet radiation (UVR) and chemical stress (triclosan-TCS; potassium dichromate-PD; prochloraz-PCZ) on bacterial communities of zebrafish (Danio rerio) embryos (ZEBC). Embryos were exposed to two UVR intensities and two chemical concentrations not causing mortality or any developmental effect (equivalent to the No-Observed-Effect Concentration-NOEC; NOEC diluted by 10-NOEC/10). Effects on ZEBC were evaluated using denaturing gradient gel electrophoresis (DGGE) and interpreted considering structure, richness and diversity. ZEBC were affected by both stressors even at concentrations/doses not affecting the host-organism (survival/development). Yet, some stress-tolerant bacterial groups were revealed. The structure of the ZEBC was always affected, mainly due to xenobiotic presence. Richness and diversity decreased after exposure to NOEC of PD. Interactive effects occurred for TCS and UVR. Aquatic microbiota imbalance might have repercussions for the host/aquatic system, particularly in a realistic scenario/climate change perspective therefore, future ecotoxicological models should consider xenobiotics interactions with UVR.

  15. 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.

  16. Precision of the EPA Seven-Day Fathead Minnow Larval Survival and Growth Test: Intra- and interlaboratory study: Final report

    SciTech Connect

    DeGraeve, G.M.; Cooney, J.D.; Pollock, T.L.; Reichenbach, N.G.; Dean, J.H.; Marcus, M.D.; McIntyre, D.O.

    1989-01-01

    The US Environmental Protection Agency (US EPA) has recently developed a ''Seven-Day Fathead Minnow Larval Survival and Growth Test'' for measuring the toxicity of effluents. This study evaluated the intra- and interlaboratory variability of this seven-day test using two reference toxicants (sodium pentachlorophenate and potassium dichromate), two treated refinery effluents, and one untreated internal utility waste stream. Ten different laboratories, representing academia, private industry, contractors, State EPA and US EPA participated in the study. The reference toxicants were tested twice during two separate test periods and each industrial effluent was treated once during a single period. Weight NOEC values were generally similar to those for survival, but had substantially greater variability than survival NOEC values. Increasing the number of replicate test chambers from two to three increased the test sensitivity and decreased the variability in NOEC values. Overall this chronic test procedure was moderately easy to carry-out for experienced laboratories and appears to be a precise method for estimating toxicity. The laboratories were able to successfully complete 126 of 140 tests. Nine of the 14 unsuccessful completed tests were invalid because survival of larvae in control exposures was below the US EPA's survival criterion of 80% for chronic bioassays. 26 refs., 13 figs., 40 tabs.

  17. Morphology of the rat cochlear primary afferents during prenatal development: a Cajal's reduced silver and rapid Golgi study.

    PubMed Central

    Angulo, A; Merchán, J A; Merchán, M A

    1990-01-01

    In this study, we analyse the process of spatial organisation of the cochlear root related to the morphological and topographical changes in the CN during the prenatal development of Wistar rats, placing special emphasis on aspects of the latero-medial distribution of the cochlear afferents. A total of 35 embryos from 8 Wistar rats was employed, corresponding to embryonic days 14, 16, 18 and 20. Twenty of these embryos were studied by the Cajal's reduced silver stain and 15 by the rapid Golgi method (osmium dichromate method). The otocyst, the vestibulo-cochlear ganglion and vestibulo-cochlear nerve were first observed at embryonic Day 14 (E14). At E16, a sharp separation between the cochlear and vestibular roots was distinguished. The final position of the primary afferents and their main branches (anterior and posterior) in the CN was observed at E18 and E20, when the total number of cochlear turns had been formed. The cochlear afferents coming from the apical coil, the last to be incorporated into the cochlear root, project their posterior branches at the bifurcation towards more medial portions of the PVCN and their anterior branches towards the more lateral regions of the AVCN. Images Fig. 1 Fig. 2 Fig. 3(Cont.) Fig. 3 Fig. 4 Fig. 5(Cont.) Fig. 5 PMID:1691163

  18. Histological Stains: A Literature Review and Case Study.

    PubMed

    Alturkistani, Hani A; Tashkandi, Faris M; Mohammedsaleh, Zuhair M

    2015-06-25

    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.

  19. 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.

  20. A microfluidic device for continuous sensing of systemic acute toxicants in drinking water.

    PubMed

    Zhao, Xinyan; Dong, Tao

    2013-12-01

    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.

  1. Reversible immobilization of uricase on conductive polyaniline brushes grafted on polyacrylonitrile film.

    PubMed

    Bayramoğlu, Gülay; Altıntaş, Begüm; Arıca, M Yakup

    2011-02-01

    Polyacrylonitrile film (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The conductive films were used for immobilization of uricase. The surface resistance of the conductive film in this work was found to be 0.97 kΩ/cm. The maximum amount of immobilized enzyme on conductive film containing 2.4% PANI was about 216 μg/cm(2). The optimum pH for free and immobilized enzymes was observed at 7.0 and 7.5, respectively. The K (m) values for free and immobilized uricase were found to be 94 and 138 μM, respectively. V (max) values were calculated as 1.87 and 1.63 U/mg protein for the free and immobilized enzymes, respectively. Immobilized uricase exhibited ~68% of its original activity even after 2 months of storage at 4 °C while the free enzyme lost its initial activity within 4 weeks. PMID:20652599

  2. Surface modification of polyacrylonitrile film by anchoring conductive polyaniline and determination of uricase adsorption capacity and activity

    NASA Astrophysics Data System (ADS)

    Bayramoğlu, Gülay; Metin, Ayşegul Ü.; Arıca, M. Yakup

    2010-09-01

    Polyacrylonitrile (PAN) films were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The effect of aniline concentration on the grafting efficiency and on the electrical surface resistance of PAN and (PAN/PANI)-1-3 composite film was investigated. The surface resistances of the conductive composite films were found to be between 6.32 and 0.97 kΩ/cm. As the amount of grafted PANI increased on the PAN films, the electrical resistance of composite film decreased. The PAN/PANI composite films were also characterized using SEM and FTIR. The changes in the surface properties of the films were characterized by contact angle measurements. As expected, the PAN, PAN/PANI and PAN/PANI-uricase immobilized films, exhibited different contact angle values and surface free energy due to different interactive functional groups of the films. The conductive films were well characterized and used for immobilization of uricase. The amount of adsorbed enzyme increases with the increase of surface concentration of grafted fibrous polyaniline polymer. The maximum amount of immobilized enzyme onto composite film containing 2.4% PANI was about 216 μg/cm 2 (i.e., PAN/PANI-3). The immobilized uricase was reused 24 times in batch wise assay in a day. Finally, the immobilized uricase enzyme system was successfully fabricated and applied to determine the uric acid level in human serum samples.

  3. 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.

  4. 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

  5. Effects of the film manufacturing procedure and development process on the holographic properties of HOE in DCG

    NASA Astrophysics Data System (ADS)

    Stojanoff, Christo G.

    2004-06-01

    The objective of this research program was the development of a technology for the industrial manufacturing of high efficiency HOE (Holographic Optical Elements) with predetermined spectral characteristics and angular selectivity ranging in format from few square millimeters to square meters. The developed technology includes the machine fabrication of precision holographic films (2 to 30 micron thickness) on glass or plastic substrata, and chemically and thermally adapted hologram development processes. The desired optical properties of the holographic material for a specific technical application are determined during the making of the film and are modified during the exposure and the development of the HOE. This is achieved through the use of filler material to swell or shrink the hologram and a specific development process to fix the desired spectral properties of the film. The developed technology extends the applicability of dichromated gelatin ( DCG) into the blue and infrared spectral domains. The effects of the holographic layer deposition and of the development process on the holographic properties are illustrated with electron-microscope photographs of the cross section of the hologram. The photographs reveal the presence of the nano-size voids that are generated during the hologram processing. These voids are regarded as the cause for bandwidth enlargement of the HOE.

  6. Histological Stains: A Literature Review and Case Study.

    PubMed

    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

  7. 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

  8. Rapid determination of the chemical oxygen demand of water using a thermal biosensor.

    PubMed

    Yao, Na; Wang, Jinqi; Zhou, Yikai

    2014-06-06

    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.

  9. 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.

  10. 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.

  11. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    PubMed

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm.

  12. 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.

  13. 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

  14. 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

  15. Gold(III) chloride catalyzed synthesis of chiral substituted 3-formyl furans from carbohydrates: application in the synthesis of 1,5-dicarbonyl derivatives and furo[3,2-c]pyridine.

    PubMed

    Mal, Kanchan; Sharma, Abhinandan; Das, Indrajit

    2014-09-01

    This report describes a gold(III)-catalyzed efficient general route to densely substituted chiral 3-formyl furans under extremely mild conditions from suitably protected 5-(1-alkynyl)-2,3-dihydropyran-4-one using H2 O as a nucleophile. The reaction proceeds through the initial formation of an activated alkyne-gold(III) complex intermediate, followed by either a domino nucleophilic attack/anti-endo-dig cyclization, or the formation of a cyclic oxonium ion with subsequent attack by H2 O. To confirm the proposed mechanistic pathway, we employed MeOH as a nucleophile instead of H2 O to result in a substituted furo[3,2-c]pyran derivative, as anticipated. The similar furo[3,2-c]pyran skeleton with a hybrid carbohydrate-furan derivative has also been achieved through pyridinium dichromate (PDC) oxidation of a substituted chiral 3-formyl furan. The corresponding protected 5-(1-alkynyl)-2,3-dihydropyran-4-one can be synthesized from the monosaccharides (both hexoses and pentose) following oxidation, iodination, and Sonogashira coupling sequences. Furthermore, to demonstrate the potentiality of chiral 3-formyl furan derivatives, a TiBr4 -catalyzed reaction of these derivatives has been shown to offer efficient access to 1,5-dicarbonyl compounds, which on treatment with NH4 OAc in slightly acidic conditions afforded substituted furo[3,2-c]pyridine.

  16. Comparison of European Standard Patch Test Results of 330 Patients from an Occupational Diseases Hospital

    PubMed Central

    Aytekin, Aslı; Tutkun, Engin; Yılmaz, Hınç

    2016-01-01

    Background and Aim. Contact dermatitis (CD) is the most prevalent occupational skin disease with a significant impact on quality of life. Patch testing is used for the identification of responsible allergens which may improve protective and preventive measures in the workplace. Herein, we aim to identify the demographic characteristics and occupation of patients with early diagnosis of occupational CD and compare patch test results. Materials and Methods. The study included 330 patients referred to our clinic between April 2009 and April 2011 and who were patch-tested with 28-allergen European Standard Test. Results. 126 (38%) patients were female and 204 (62%) were male with a mean age of 36.12 (±13.13) years. Positive allergic reactions were observed in 182 (55%) patients. Nickel sulphate (41/126) and potassium dichromate (39/204) were significantly the most common allergens in women and men, respectively (P < 0.005). Additionally, the most common occupation in women was household activities (83/126) and in men was manufacturing (80/204). Conclusion. The allergens to which people become sensitized differ according to their working environment and occupation. Classification of occupations is important for identification of sensitization risks and monitoring of changes in allergen distribution of different occupations. PMID:27807445

  17. 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

  18. 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.

  19. Validation and application of a thermal-optical reflectance (TOR) method for measuring black carbon in loess sediments.

    PubMed

    Zhan, Changlin; Han, Yongming; Cao, Junji; Wei, Chong; Zhang, Jiaquan; An, Zhisheng

    2013-06-01

    Three techniques were used to measure black carbon (BC) in samples from Chinese loess-paleosol sequences. The results obtained by (1) chemo-thermal oxidation (CTO, performed two ways), (2) acid dichromate oxidation (Cr2O7), and (3) thermal-optical reflectance (TOR) were intercompared because prior studies have shown that the methods can yield disparate results. BC concentrations did vary among the methods, most likely because they measured different components of the BC continuum, but the high-temperature BC (soot) determined by CTO was correlated with the BC and soot obtained by TOR. The CTO and TOR methods both yielded statistically significant linear relationships for loess and lake sediments that had incremental additions of a standard (SRM-1649a). The results also showed that charred material was more abundant in these test sediments than soot carbon. Data for BC in Luochuan loess generated using TOR showed a trend similar to that of magnetic susceptibility, that is, high BC and large susceptibilities during the last interglacial and low values for both variables in the last glacial. The results thus indicate that the TOR method is well suited for studies of sedimentary materials and that more biomass burned during the last interglacial than in the last glacial.

  20. Volume phase holographic grating used for beams combination of RGB primary colors

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Zhang, Xizhao; Tang, Minxue

    2013-12-01

    Volume phase holographic grating (VPHG) has the characteristics of high diffraction efficiency, high signal to noise ratio, high wavelength and angular selectivity, low scattering , low absorption and low cost. It has been widely used in high resolution spectrometer, wavelength division multiplexing and pulse compression technique. In this paper, a novel kind of RGB primary colors beams combiner which is consisted of a transmission VPHG and a reflection VPHG as core components is proposed. The design idea of the element is described in detail. Based on the principle of VPHG, the rigorous coupled wave analysis (RCWA) and Kogelnik's coupled wave theory, diffraction properties of the transmission and reflection VPHG are studied theoretically. As an example, three primary colors at wavelengths of 632.8nm, 532nm and 476.5nm are taken into account. Dichromated gelatin (DCG) is used as the holographic recording material. The grating parameters are determined by the Bragg conditions. The TE and TM wave diffraction efficiency, the wavelength selectivity and the angular selectivity of the transmission and reflection VPHG are calculated and optimized by setting the amplitude of the index modulation (Δn) and the thickness of the gelatin layer (d) by applying Kogelnik's coupled wave theory and G-solver software, respectively. The theoretical calculating results give guidance for further manufacture of the element.

  1. 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.

  2. 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

  3. Chronic exposure to sublethal hexavalent chromium affects organ histopathology and serum cortisol profile of a teleost, Channa punctatus (Bloch).

    PubMed

    Mishra, Ashish K; Mohanty, Banalata

    2009-09-01

    Effects of chronic exposures (one and two months) to sublethal doses of hexavalent chromium (2 and 4 mg/L potassium dichromate) on organ histopathology and serum cortisol profile were investigated and their overall impact on growth and behavior of a teleost fish, Channa punctatus was elucidated. Histopathological lesions were distinct in the vital organs gill, kidney and liver. The gill lamellae became lifted, fused, and showed oedema. Hyperplasia and hypertrophy of lamellar epithelial cells were distinct with desquamation. Hypertrophy of epithelial cells of renal tubules and reduction in tubular lumens were observed in the trunk kidney. The atrophy of the head kidney interrenal cells and decreased serum cortisol level indicated exhaustion of interrenal activity. Hepatocyte vacuolization and shrinkage, nuclear pyknosis and increase of sinusoidal spaces were observed in the liver. Abnormal behavioral patterns and reduced growth rate were also noticed in the exposed fish. The chronic hexavalent chromium exposure thus by affecting histopathology of gill, kidney (including interrenal tissue) and liver could impair the vital functions of respiration, excretion, metabolic regulation and maintenance of stress homeostasis which in the long-run may pose serious threat to fish health and affect their population.

  4. 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

  5. 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

  6. 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

  7. 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

  8. Comparison of thermophilic anaerobic digestion characteristics between single-phase and two-phase systems for kitchen garbage treatment.

    PubMed

    Park, YongJin; Hong, Feng; Cheon, JiHoon; Hidaka, Taira; Tsuno, Hiroshi

    2008-01-01

    Lab-scale single-phase and two-phase thermophilic methane fermentation systems (SPS and TPS, respectively) were operated and fed with artificial kitchen waste. In both SPS and TPS, the highest methane recovery ratio of 90%, in terms of chemical oxygen demand by dichromate (CODcr), was observed at an organic loading rate (OLR) of 15 gCODcr/(l.d). The ratio of particle CODcr remaining to total CODcr in the influent was 0.1 and the ratio of NH(4)-N concentration to the input total nitrogen concentration was 0.5 in both SPS and TPS. However, the propionate concentration in the SPS reactor fluctuated largely and was 2 gCODcr/l higher than that in TPS, indicating less stable digestion. Regardless, efficient kitchen waste degradation can be accomplished in both SPS and TPS at an OLR of <20 gCODcr/(l.d), even though TPS may be more stable and easier to maintain. Bacillus coagulans predominated with an occupied ratio of approximately 90% in the acid fermentation reactor of TPS, and then a richer microbial community with a higher Shannon index value was maintained in the methane fermentation reactor of TPS than in the SPS reactor. PMID:18295719

  9. 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

  10. 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

  11. A Case of Chromium Contact Dermatitis due to Exposure from a Golf Glove

    PubMed Central

    Lim, Jong Ho; Kim, Hei Sung; Park, Young Min; Lee, Jun Young

    2010-01-01

    Chromium is a transition metal and has been shown to elicit contact dermatitis. Although leather products have been known to be the most significant source of chromium exposure these days, the majority of reports have been related to exposure from shoe products. We herein report a professional golfer who became allergic to golf gloves made of chromium-tanned leather. A 27-year-old woman golfer presented with recurrent, pruritic, erythematous plaques that had been occurring on both hands for several years. The lesions developed whenever she had worn golf gloves for an extended period of time, especially during tournament season. To identify the causative agent, patch tests were performed and the results demonstrated a strong positive reaction to potassium dichromate 0.5% and to her own glove. The amount of chromium in her golf glove was analyzed to be 308.91 ppm and based on this, a diagnosis of allergic contact dermatitis due to a chromium-tanned leather glove was made. She was treated with oral antihistamines combined with topical steroids and advised to wear chromium-free leather gloves. There has been no evidence of recurrence during a six month follow-up period. PMID:20548885

  12. Toxicity and Mutagenicity of Hexavalent Chromium on Salmonella typhimurium

    PubMed Central

    Petrilli, Fernando L.; De Flora, Silvio

    1977-01-01

    Four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the Salmonella typhimurium/mammalian-microsome test. All hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 μg/plate, a significant increase of his+ revertant colonies at doses ranging from 10 to 200 μg, and no effect at doses of less than 10 μg. The distinctive sensitivity of the four Salmonella strains tested (TA1535, TA1537, TA98, and TA100) suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions. The latter mutations, which are prevalent, are amplified by an error-prone recombinational repair of the damaged deoxyribonucleic acid. On the average, 1 μmol of hexavalent chromium yielded approximately 500 revertants of the TA100 strain, irrespective of the compound tested (sodium dichromate, calcium chromate, potassium chromate, or chromic acid). The mutagenic potency of the hexavalent metal was not enhanced by adding the microsomal fraction of rat hepatocytes, induced either with sodium barbital or with Aroclor 1254. The two trivalent compounds (chromium potassium sulfate and chromic chloride), with or without the microsomal fraction, were neither toxic nor mutagenic for the bacterial tester strains. Images PMID:326184

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

    PubMed

    Subramanian, Senthivinayagam; 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. PMID:16678873

  14. A Case of Chromium Contact Dermatitis due to Exposure from a Golf Glove.

    PubMed

    Lim, Jong Ho; Kim, Hei Sung; Park, Young Min; Lee, Jun Young; Kim, Hyung Ok

    2010-02-01

    Chromium is a transition metal and has been shown to elicit contact dermatitis. Although leather products have been known to be the most significant source of chromium exposure these days, the majority of reports have been related to exposure from shoe products. We herein report a professional golfer who became allergic to golf gloves made of chromium-tanned leather. A 27-year-old woman golfer presented with recurrent, pruritic, erythematous plaques that had been occurring on both hands for several years. The lesions developed whenever she had worn golf gloves for an extended period of time, especially during tournament season. To identify the causative agent, patch tests were performed and the results demonstrated a strong positive reaction to potassium dichromate 0.5% and to her own glove. The amount of chromium in her golf glove was analyzed to be 308.91 ppm and based on this, a diagnosis of allergic contact dermatitis due to a chromium-tanned leather glove was made. She was treated with oral antihistamines combined with topical steroids and advised to wear chromium-free leather gloves. There has been no evidence of recurrence during a six month follow-up period. PMID:20548885

  15. 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

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

    PubMed

    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

  17. 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

  18. 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

  19. Holographic Recordings in Dye/Polymer Systems For Engineering Applications

    NASA Astrophysics Data System (ADS)

    Lessard, Roger A.; Couture, Jean J.

    1990-04-01

    Since Gabor's first demonstration of reconstructed wavefronts, many holographic techniques provided interesting tools and applications. Presently the future of holography is strongly dependent upon new holographic recording thin films. Because of their excellent responses to high spatial frequency grating recordings (up to 6800 cycles/mm), photopolymers and photocrosslinking materials seem to be good candidates to overcome some limitations. Dichromated gelatin films demons-trated excellent properties for permanent recording grating applications like HOE construction but they are humidity sensitive and they need a chemical development. Today's holographic works need real-time like recording material and law cost organic materials as DYE/POLYMER systems offer some possibilities. We present a review of research works done in our holography laboratories of COPL at Universite Laval. Using an automated spatial frequency analyzer designed at COPL, DYE/POLYMER systems are characterized for transmission holography and also for applications involving real-time holography and four-wave mixing techniques. Also, most of our characterization studies consider volume polarization holograms. The second subject is devoted to polarization hologram recordings in thin colored polyvinyl alcohol films. Those AZO/WA solid films are erasable and can be used for many thousands duty cycles for polarization volume holograms. Holographic characterization studies are conducted in order to know best experimental conditions and applications that allow to use those films. Finally, sensitized PVA films will be discussed.

  20. 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

  1. Non-invasive methods for identifying oocysts of Sarcocystis spp. from definitive hosts.

    PubMed

    Xiang, Zheng; Chen, Xinwen; Yang, Lijun; He, Yongshu; Jiang, Runsheng; Rosenthal, Benjamin M; Luan, Pengtao; Attwood, S W; Zuo, Yangxian; Zhang, Ya-ping; Yang, Zhaoqing

    2009-09-01

    Because the excreted sporocysts and/or oocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts and/or sporocysts from three taxa of Sarcocystis were collected from human, feline, and canine definitive hosts that had fed upon meats infected with the muscle cysts of Sarcocystis hominis, Sarcocystis fusiformis and a species of Sarcocystis from water buffalo that could not be distinguished from Sarcocystis cruzi. Using a new collection method employing filter paper, these excreted oocysts and sporocysts were subjected to DNA extraction, as were the corresponding muscle cysts. Methods employing PCR-RFLP and DNA sequencing of a partial 18S rDNA gene (ssrRNA) sequence were then used to successfully distinguish among the three taxa. The same, unique restriction digestion pattern characterizes the tissue cysts and oocysts and/or sporocysts of each parasite taxon. The technique makes possible amplification and identification of species specific gene sequences based on DNA extracted from as few as 7 excreted sporocysts (the equivalent of 3 and 1/2 oocysts) from freshly prepared material, or as few as 50 sporocysts from feces samples that had been stored in potassium dichromate (K2Cr2O7) for as long as 6 years. This represents the first report using molecular diagnostic procedures to diagnose oocysts of Sarcocystis in faecal samples, describing a valuable new tool for studying the epidemiology of various Sarcocystis species.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part 2. Reflection holographic optical elements.

    PubMed

    Kim, Jong Man; Choi, Byung So; Choi, Yoon Sun; Kim, Jong Min; Bjelkhagen, Hans I; Phillips, Nicholas J

    2002-03-10

    Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOEs). The drawback of DCG is its low energetic sensitivity and limited spectral response. Silver halide materials can be processed in such away that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-fine-grain silver halide (AgHal) emulsions. In particular, high spatial-frequency fringes associated with HOEs of the reflection type are difficult to construct when SHSG processing methods are employed. Therefore an optimized processing technique for reflection HOEs recorded in the new AgHal materials is introduced. Diffraction efficiencies over 90% can be obtained repeatably for reflection diffraction gratings. Understanding the importance of a selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOEs, also including high-quality display holograms of the reflection type in both monochrome and full color.

  8. Common contact sensitizers in Delhi.

    PubMed

    Singhal, V; Reddy, B S

    2000-07-01

    Seventy-five patients of both sexes with clinically suspected contact dermatitis were patch tested with the Indian Standard Series and indigenous antigens. The results were compared with the data from other centers. Most of these patients were young adults between 20 and 39 yrs old with the mean age of 36.63 +/- 5.6 yrs. Their occupational profiles included household workers (17.33%), masons (10.66%), farmers (6.66%), factory workers (4%), medical personnel (4%), lab workers (2.66%), and miscellaneous (17.33%). Itching and burning were two of the most common complaints, and chronic dermatitis was the predominant morphologic pattern of the lesions observed. Frequent sites involved included the hands (40.83%), airborne type (22.44%), hands and feet (12.24%), feet (12.24%), face (10.2%), and neck (2.04%). Patch test analysis of these patients revealed that, out of 75 subjects tested, 49 (65.3%) reacted to one or more allergens. Parthenium (20%) is the most common contact sensitizer followed by potassium dichromate (16%), xanthium (13.33%), nickel sulphate (12%), chrysanthemum (8%), mercaptobenzothiazole, and garlic (6.66% each). These findings are in broad conformity with those in other reports. We concluded that the Indian Standard Series of antigens with the addition of a few more (such as garlic, onion and chlorheximide of local relevance) is suitable for detecting the allergens responsible for the contact dermatitis prevailing in this region. PMID:10935340

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  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. 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. 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. Non-Arrhenian Multicomponent Melts Viscosity: Extension of the Model.

    NASA Astrophysics Data System (ADS)

    Mangiacapra, A.; Giordano, D.; Potuzak, M.; Dingwell, D. B.; Russell, J. K.

    2003-12-01

    Viscosity exerts a strong control on many magmatic and petrological processes on micro- and macroscopic scales. Furthermore, knowledge of such a property gives important constraints for structural theories of silicate melts. Giordano and Dingwell (GD)[1] recently described the viscosity of a large number of silicate melts coping a wide compositional range, on the basis of an empirical parameter (SM), sum on a molar basis of the network modifying cations. That model does not consider the contribution of the iron oxidation state to influencing the viscosity. Here, this is rectified. In this experimental study we have doubled (over 700 data) the number of viscosity determinations input into the model provided by [1] extending the compositional basis to further rhyolitic, trachytic, moldavitic, andesitic, latitic, pantelleritic, basaltic and basanitic melt compositions. The effect of Fe2+/Fe3+ on viscosity has been expressly examined. The temperature-dependence of the new liquid compositions have been investigated at high temperature (1050-1600° C) and low temperature (616-860° C) by using a concentric cylinder apparatus and the micropenetration technique, respectively. Fe2+/Fe3+ ratio has been determined by combining a wet chemistry technique (potassium dichromate titration) with microprobe analysis for each sample, before and after the high and low-T viscometry. Viscosity parameterization along the lines of the GD model, and incorporating the constraint that the high-T viscosities converge to a common value [2], reveal very good agreement with those calculated by [1]. Explicit redox influences appear to be small. [1] D.Giordano, D.B. Dingwell, 2003. Earth Planet. Sci. Lett. 208, 337-349; [2] J.K. Russell, D. Giordano, D.B. Dingwell, 2003, Am. Mineral. 88, 1390-1394.

  18. 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.

  19. Variability in oxidative degradation of charcoal: Influence of production conditions and environmental exposure

    NASA Astrophysics Data System (ADS)

    Ascough, P. L.; Bird, M. I.; Francis, S. M.; Thornton, B.; Midwood, A. J.; Scott, A. C.; Apperley, D.

    2011-05-01

    Charcoal is a key component of the Black Carbon (BC) continuum, where BC is characterized as a recalcitrant, fire-derived, polyaromatic material. Charcoal is an important source of palaeoenvironmental data, and of great interest as a potential carbon sink, due to its high apparent environmental stability. However, at least some forms of charcoal are clearly susceptible to environmental alteration and degradation over relatively short timescales. Although these processes have importance for the role of charcoal in global biogeochemistry, they remain poorly understood. Here we present results of an investigation into the susceptibility of a range of charcoal samples to oxidative degradation in acidified potassium dichromate. The study examines both freshly-produced charcoal, and charcoal exposed to environmental conditions for up to 50,000 years. We compare the proportion of carbon present in different forms between the samples, specifically with respect to the relative chemical resistance of these forms. This was undertaken in order to improve understanding of the post-depositional diagenetic changes affecting charcoal within environmental deposits. A wide range in chemical compositions are apparent both within and between the sample groups. In freshly-produced charcoal, material produced at 300 °C contains carbon with more labile forms than charcoal produced at ⩾400 °C, signifying a key chemical change over the 300-400 °C temperature range. Charcoal exposed to environmental depositional conditions is frequently composed of a highly carboxylated aromatic structure and contains a range of carbon fractions of varying oxidative resistance. These findings suggest that a significant number of the environmental charcoals have undergone post-depositional diagenetic alteration. Further, the data highlight the potential for the use of controlled progressive oxidative degradation as a method to characterize chemical differences between individual charcoal samples.

  20. 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.

  1. 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.

  2. Extending and improving a non-arrhenian model to predict newtonian viscosities of natural silicate melts

    NASA Astrophysics Data System (ADS)

    Mangiacapra, A.; Giordano, D.; Potuzak, M.; Dingwell, D. B.

    2003-04-01

    Viscosity is one of the most important properties governing igneous processes. It is known that viscosity is a function of temperature, bulk composition, crystals, bubbles and volatiles content, and is a reflection of melt structure. Several equations and models describing the viscosity-temperature relationship and incorporating both high and low viscosity data already exist. These models are however insufficient in at least one important aspect: they only apply to limited ranges of composition. Recently a new model [1] based on the VFT equation takes into account the chemical composition of the investigated samples. Here we have extended the compositional range over which that model was calibrated. The effect of Fe 2+/Fe 3+ on viscosity has also been examined. New data presented here are for a wide range of natural compositions from different eruptive environments: rhyolitic, trachytic, moldavitic, andesitic, latitic, pantelleritic, basaltic and basanitic. Dry Newtonian shear viscosities were investigated at high temperature (1050-1600 oC) and low temperature (616-860 oC) using the concentric cylinder apparatus and the micropenetration technique, respectively. Results to date indicate good agreement between measured viscosities data and calculated data from the model [1]. Fe 2+ content has been determined wet chemically(potassium dichromate titration), for each sample. In the current work a temperature-dependent partitioning of Fe between network forming (Fe 3+) and network modifying (Fe 2+) roles has been obtained. We have found that by adding this effect, the accuracy of the viscosity model [1] is improved. [1] D.Giordano, D.B. Dingwell, 2003. Earth Planet. Sci. Lett. In press.

  3. 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

  4. 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

  5. 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

  6. Evaluation of methyl tert-butyl ether (MTBE) as an interference on commercial breath-alcohol analyzers.

    PubMed

    Buckley, T J; Pleil, J D; Bowyer, J R; Davis, J M

    2001-12-01

    Anecdotal reports suggest that high environmental or occupational exposures to the fuel oxygenate methyl tert-butyl ether (MTBE) may result in breath concentrations that are sufficiently elevated to cause a false positive on commercial breath-alcohol analyzers. We evaluated this possibility in vitro by establishing a response curve for simulated breath containing MTBE in ethanol. Two types of breath-alcohol analyzers were evaluated. One analyzer's principle of operation involves in situ wet chemistry (oxidation of ethanol in a potassium dichromate solution) and absorption of visible light. The second instrument uses a combination of infrared absorption and an electrochemical sensor. Both types of instruments are currently used, although the former method represents older technology while the latter method represents newer technology.The percent blood alcohol response curve was evaluated over a breath concentration range thought to be relevant to high-level environmental or occupational exposure (0-361 microg/l). Results indicate that MTBE positively biases the response of the older technology Breathalyzer when evaluated as a single constituent or in combination with ethanol. We conclude that a false positive is possible on this instrument if the MTBE exposure is very high, recent with respect to testing, and occurs in combination with ethanol consumption. The interference can be identified on the older technology instrument by a time dependent post-reading increase in the instrument response that does not occur for ethanol alone. In contrast, the newer technology instrument using infrared and electrochemical detectors did not respond to MTBE at lower levels (0-36 microg/l), and at higher levels (>72 microg/l) the instrument indicated an "interference" or "error". For this instrument, a false positive does not occur even at high MTBE levels in the presence of ethanol. PMID:11728735

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Diffusion of dissolved ions from wet silica sol-gel monoliths: implications for biological encapsulation.

    PubMed

    Dickson, David J; Lassetter, Bethany; Glassy, Benjamin; Page, Catherine J; Yokochi, Alexandre F T; Ely, Roger L

    2013-02-01

    Divalent nickel (Ni(2+)), Cu(II)EDTA, methyl orange, and dichromate were used to investigate diffusion from hydrated silica sol-gel monoliths. The objective was to examine diffusion of compounds on a size regime relevant to supporting biological components encapsulated within silica gel prepared in a biologically compatible process space with no post-gelation treatments. With an initial sample set, gels prepared from tetraethoxysilane were explored in a factorial design with Ni(2+) as the tracer, varying water content during hydrolysis, acid catalyst present during hydrolysis, and the final concentration of silica. A second sample set explored diffusion of all four tracers in gels prepared with aqueous silica precursors and a variety of organically modified siloxanes. Excluding six outliers which displayed significant syneresis, the mean diffusion constant (D(gel)) across the entire process space of sample set 1 was 2.42×10(-10) m(2) s(-1); approximately 24% of the diffusion coefficient of Ni(2+) in unconfined aqueous solution. In sample set 2, the tracer size and not gel hydrophobicity was the primary determinant of changes in diffusion rates. A strong linear inverse correlation was found between tracer size and the magnitude of D(gel). Based on correlation with the tracers used in this investigation, the characteristic 1-h diffusion distance for carbonate species relevant to supporting active phototrophic organisms was approximately 1.5mm. These results support the notion that silica sol-gel formulations may be optimized for a given biological entity of interest with manageable impact to the diffusion of small ions and molecules.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. Genome-wide gene expression effects in B6C3F1 mouse intestinal epithelia following 7 and 90days of exposure to hexavalent chromium in drinking water.

    PubMed

    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 90days of exposure to 0, 0.3, 4, 14, 60, 170 or 520mg/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(50) values ranging from 10 to 100mg/L SDD. Only 16 genes satisfying the dose-dependent differential expression criteria had EC(50) values <10mg/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.

  20. 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.

  1. Patch-test reaction patterns in patients with a predisposition to atopic dermatitis.

    PubMed

    Brasch, Jochen; Schnuch, Axel; Uter, Wolfgang

    2003-10-01

    Patients with a predisposition to atopic dermatitis often need to be patch tested in order to detect possible contact sensitization. However, it is unknown whether immunologic or other peculiarities of atopic skin are related to altered patch-test reaction patterns. Our study was aimed at answering this question, because patch-test reaction patterns are of considerable practical importance in the reading and interpretation of patch tests. Therefore, we compared patterns of patch-test reactions in patients with a predisposition to atopic dermatitis and in control patients matched for sex, age, reason for testing and test centre. Patch-test results from 9 centres (2322 patients with a disposition to atopic dermatitis and 2126 matched controls) were evaluated retrospectively. All patients were tested with nickel sulfate, fragrance mix, potassium dichromate, lanolin alcohol, formaldehyde and mercury ammonium chloride. Patch tests applied for 1 day with readings on days 1, 2 and 3 were evaluated in order to cover the early phase of the reactions. Not unexpectedly, we found that, compared to the matched controls, patients with a predisposition to atopic dermatitis tended to have more doubtful and irritant reactions on day 1. As a new observation, it turned out that they had less reactions of crescendo pattern and more strong reactions on day 3. All these differences were slight/insignificant. A higher skin irritability in patients with a predisposition to atopic dermatitis is a likely explanation. In conclusion, standard methods for patch testing can be applied in patients with a predisposition to atopic dermatitis, but minor differences in reaction patterns should be considered.

  2. Occupational hand dermatitis in a tertiary referral dermatology clinic in Taipei.

    PubMed

    Sun, C C; Guo, Y L; Lin, R S

    1995-12-01

    Occupational skin disease is one of the most common occupational diseases. The hand is the most frequent site of involvement in occupational skin disease. We interviewed and examined patients seen in the Contact Dermatitis Clinic of the National Taiwan University Medical Center, a tertiary referral center in Taipei City. For patients suspected of having allergic skin diseases, patch testing was carried out using the European standard series and suspected allergens. Occupational hand dermatitis (OHD) was diagnosed according to medical history, work exposure, physical examination, and patch test findings. 36% of patients seen were diagnosed as having OHD. Electronics, hairdressing, medical, chemical, and construction were the most important industries causing OHD. In the 164 patients with OHD, 58.5% had irritant contact dermatitis (ICD) and 41.5% allergic contact dermatitis (ACD). Dorsal fingers, nail folds, and dorsal hands were most frequently involved in patients with ACD; dorsal fingers, volar fingers and fingertips were most frequently involved in those with ICD. Using logistic regression analysis, we were able to identify the most important clinical presentations that predicted the types of OHD, ACD versus ICD. Patients with atopic history and palm involvement were more likely to have ICD, and those with nail fold involvement more likely to have ACD. In patients with ACD, the most important allergens were dichromate, nickel, cobalt, fragrance mix, epoxy resin, thiuram mix, and p-phenylenediamine. In this study, we identified the important industries and causal agents for OHD. Future preventive measures focused on these industries and agents to reduce OHD will be warranted.

  3. 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.

  4. Comparison of semiautomated method with official optical somatic cell counting method III for determining somatic cells in milk.

    PubMed

    Mochrie, R D; Dickey, D A

    1984-01-01

    The new method specifying the Fossomatic-90 differs from the official method, 46.105-46.109, in that the modified instrument includes a halogen lamp; a semiconductor photoelectric detector; a less expensive, bench-top cabinet; manual injection of a larger sample, and a reduced capacity. The new instrument was compared with 2 optical somatic cell counters in routine use. On each of 3 days, 12 subsamples were prepared for each of 5 cell count levels from AM milk with half kept fresh and half preserved with 0.05% potassium dichromate. Subsamples were refrigerated and read 30+ h post-collection. Duplicate sets were read in random order on each machine daily (CV 0.77%). Two sets of slides read by 2 technicians each (strip reticle on 2 smears/slide) gave geometric mean direct microscopic somatic cell count (DMSCC) levels of 296, 526, 772, 930, and 1438 th/mL. Within-technician CV values (from day-level means) ranged from 1.68 to 2.28%. Geometric mean cells in th/mL on the new machine were significantly higher than those on the other two (674 vs 621) and were closer to the DMSCC (694). On the new machine, cell counts were 8.5% greater than on the original machines, were only 2.9% lower than the DMSCC, and showed no significant evidence of bias. Preserved samples averaged slightly greater than fresh (5.3%) but only on the original machines. Carryover by covariance analysis was insignificant. Except for cell levels, high machine precision (error CV value of 1.18%) gave differences with statistical but not practical significance, even for regulatory laboratories. PMID:6378874

  5. 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

  6. 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.

  7. Comparison of the effects of hexavalent chromium in the alimentary canal of F344 rats and B6C3F1 mice following exposure in drinking water: implications for carcinogenic modes of action.

    PubMed

    Thompson, Chad M; Proctor, Deborah M; Suh, Mina; Haws, Laurie C; Hébert, Charles D; Mann, Jill F; Shertzer, Howard G; Hixon, J Gregory; Harris, Mark A

    2012-01-01

    Exposure to high concentrations of hexavalent chromium (Cr[VI]) in drinking water is reported to induce oral mucosa tumors in F344 rats and intestinal tumors in B6C3F1 mice. To investigate the modes of action underlying these tumors, 90-day drinking water studies (with interim necropsy at day 8) were conducted with concentrations of 0.1-182 mg/l Cr(VI), administered as 0.3-520 mg/l sodium dichromate dihydrate. Blood and tissue samples were analyzed for chromium content, oxidative stress, iron levels, and gross and microscopic lesions. Results for the F344 rats are described herein and compared with results from B6C3F1 mice published previously. After 90 days of exposure, total chromium concentrations in the rat and mouse oral mucosae were comparable, yet significant dose-dependent decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed only in rats. In the duodenum, changes in GSH/GSSG were only observed in mice. Levels of 8-hydroxydeoxyguanosine were not increased in the oral or duodenal mucosae of either species. Glutathione levels were increased in the duodenum but decreased in the jejunum of both species, indicating potential differential responses in the intestinal segments. Histiocytic infiltration was observed in the duodenum of both species, yet duodenal cytokines were repressed in mice but increased in rats. Serum and bone marrow iron levels were more decreased in rats than mice. Collectively, these data suggest that Cr(VI)-induced carcinogenesis in the rodent alimentary canal involves oxidative stress; however, differences in histopathology, cytokines, and iron status suggest potential contributions from other factors as well.

  8. Investigation of the mode of action underlying the tumorigenic response induced in B6C3F1 mice exposed orally to hexavalent chromium.

    PubMed

    Thompson, Chad M; Proctor, Deborah M; Haws, Laurie C; Hébert, Charles D; Grimes, Sheila D; Shertzer, Howard G; Kopec, Anna K; Hixon, J Gregory; Zacharewski, Timothy R; Harris, Mark A

    2011-09-01

    Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice. To investigate the mode of action (MOA) underlying these tumors, a 90-day drinking water study was conducted using similar exposure conditions as in a previous cancer bioassay, as well as lower (heretofore unexamined) drinking water concentrations. Tissue samples were collected in mice exposed for 7 or 90 days and subjected to histopathological, biochemical, toxicogenomic, and toxicokinetic analyses. Described herein are the results of toxicokinetic, biochemical, and pathological findings. Following 90 days of exposure to 0.3-520 mg/l of sodium dichromate dihydrate (SDD), total chromium concentrations in the duodenum were significantly elevated at ≥ 14 mg/l. At these concentrations, significant decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed. Beginning at 60 mg/l, intestinal lesions were observed including villous cytoplasmic vacuolization. Atrophy, apoptosis, and crypt hyperplasia were evident at ≥ 170 mg/l. Protein carbonyls were elevated at concentrations ≥ 4 mg/l SDD, whereas oxidative DNA damage, as assessed by 8-hydroxydeoxyguanosine, was not increased in any treatment group. Significant decreases in the GSH/GSSG ratio and similar histopathological lesions as observed in the duodenum were also observed in the jejunum following 90 days of exposure. Cytokine levels (e.g., interleukin-1β) were generally depressed or unaltered at the termination of the study. Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice.

  9. 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

  10. 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

  11. 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.

  12. Chromium (VI) induced changes in growth and root plasma membrane redox activities in pea plants.

    PubMed

    Pandey, Vivek; Dixit, Vivek; Shyam, Radhey

    2009-03-01

    The effect of chromium (Cr) on growth as well as root plasma membrane redox reactions and superoxide radical production was studied in pea (Pisum sativum L. cv. Azad) plants exposed for 7 days to 20 and 200 microM Cr (VI), respectively, supplied as potassium dichromate. The growth of pea plants declined significantly at 200 microM Cr, as indicated by reduced leaf area and biomass. Relative to the control plants (no Cr exposure), the Cr content of roots increased significantly, both at 20 and 200 microM Cr. Following exposure to 200 microM Cr, there was a significant increase in root lipid peroxidation and hydrogen peroxide (H(2)O(2)) content, while both the Fv/Fm ratio and chlorophyll content were reduced. Exposure to Cr increased NADPH-dependent superoxide production in pea root plasma membrane vesicles, with the effect being more significant at 200 microM Cr than at 20 microM Cr. Treatment with Cr rapidly increased the activities of NADPH oxidase: relative to the controls, plants exposed to 20 microM Cr showed approximately a 67% increase in activity while there was a threefold increase in those plants exposed to 200 microM Cr. NADH-ferricyanide oxido-reductase activity was found to be inhibited by 16 and 51% at 20 and 200 microM Cr, respectively. The results of this study suggest that exposure to excess Cr damages pea root plasma membrane structure and function, resulting in decreased photosynthesis and poor plant growth.

  13. 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

  14. 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

  15. Artificial extracellular matrix proteins containing phenylalanine analogues biosynthesized in bacteria using T7 expression system and the PEGylation.

    PubMed

    Takasu, Akinori; Kondo, Shiori; Ito, Akihiro; Furukawa, Yuya; Higuchi, Masahiro; Kinoshita, Takatoshi; Kwon, Inchan

    2011-10-10

    In vivo incorporation of phenylalanine (Phe) analogues into an artificial extracellular matrix protein (aECM-CS5-ELF) was accomplished using a bacterial expression host that harbors the mutant phenylalanyl-tRNA synthetase (PheRS) with an enlarged binding pocket. Although the Ala294Gly/Thr251Gly mutant PheRS (PheRS**) under the control of T5 promoter allows incorporation of some Phe analogues into a protein, the T5 system is not suitable for material science studies because the amount of materials produced is not sufficient due to the moderate strength of the T5 promoter. This limitation can be overcome by using a pair of T7 promoter and T7 RNA polymerase instead. In the T7 expression system, it is difficult, however, to achieve a high incorporation level of Phe analogues, due to competition of Phe analogues for incorporation with the residual Phe that is required for synthesis of active T7 RNA polymerase. In this study, we prepared the PheRS** under T7 promoter and optimized culture condition to improve both the incorporation level of recombinant aECM protein and the incorporation level of Phe analogues. Incorporation and expression levels tend to increase in the case of p-azidophenylalanine, p-iodophenylalanine, and p-acetylphenylalanine. We evaluated the lower critical transition temperature, which is dependent on the incorporation ratio and the turbidity decreased when the incorporation level increased. Circular dichromism measurement indicated that this tendency is based on conformational change from random coil to β-turn structure. We demonstrated that polyethylene glycol (PEG) can be conjugated at reaction site of Phe analogues incorporated. We also demonstrated that the increased hydrophilicity of elastin-like sequences in the aECM-CS5-ELF made by PEG conjugation could suppress nonspecific adhesion of human umbilical vein endothelial cells (HUVEC).

  16. 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

  17. 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.

  18. 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.

  19. Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium.

    PubMed

    Pedersen, P; Thomsen, E; Stern, R M

    1983-09-01

    The replica plating method as developed by Lederberg has been used to differentiate between "true" and "false" histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of "false" revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between "true" and "false" revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting "revertant" colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Activation of the nuclear receptor FXR enhances hepatocyte chemoprotection and liver tumor chemoresistance against genotoxic compounds.

    PubMed

    Vaquero, Javier; Briz, Oscar; Herraez, Elisa; Muntané, Jordi; Marin, Jose J G

    2013-10-01

    The success of pharmacological treatments in primary liver cancers is limited by the marked efficacy of mechanisms of chemoresistance already present in hepatocytes. The role of the nuclear receptor FXR is unclear. Although, in non-treated liver tumors, its expression is reduced, the refractoriness to anticancer drugs is high. Moreover, the treatment with cisplatin up-regulates FXR. The aim of this study was to investigate whether FXR is involved in stimulating chemoprotection/chemoresistance in healthy and tumor liver cells. In human hepatocytes, the activation of FXR with the agonist GW4064 resulted in a significant protection against cisplatin-induced toxicity. In human hepatoma Alexander cells, with negligible endogenous expression of FXR, GW4064 also protected against cisplatin-induced toxicity, but only if they were previously transfected with FXR/RXR. Investigation of 109 genes potentially involved in chemoresistance revealed that only ABCB4, TCEA2, CCL14, CCL15 and KRT13 were up-regulated by FXR activation both in human hepatocytes and FXR/RXR-expressing hepatoma cells. In both models, cisplatin, even in the absence of FXR agonists, such as bile acids and GW4064, was able to up-regulate FXR targets genes, which was due to FXR-mediated trans-activation of response elements in the promoter region. FXR-dependent chemoprotection was also efficient against other DNA-damaging compounds, such as doxorubicin, mitomycin C and potassium dichromate, but not against non-genotoxic drugs, such as colchicine, paclitaxel, acetaminophen, artesunate and sorafenib. In conclusion, ligand-dependent and independent activation of FXR stimulates mechanisms able to enhance the chemoprotection of hepatocytes against genotoxic compounds and to reduce the response of liver tumor cells to certain pharmacological treatments.

  1. 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.

  2. Whole adult organism transcriptional profiling of acute metal exposures in male Zebrafish

    PubMed Central

    2014-01-01

    Background A convergence of technological breakthroughs in the past decade has facilitated the development of rapid screening tools for biomarkers of toxicant exposure and effect. Platforms using the whole adult organism to evaluate the genome-wide response to toxicants are especially attractive. Recent work demonstrates the feasibility of this approach in vertebrates using the experimentally robust zebrafish model. In the present study, we evaluated gene expression changes in whole adult male zebrafish following an acute 24 hr high dose exposure to three metals with known human health risks. Male adult zebrafish were exposed to nickel chloride, cobalt chloride or sodium dichromate concentrations corresponding to their respective 96 hr LC20, LC40 and LC60. Histopathology was performed on a subset of metal-exposed zebrafish to phenotypically anchor transcriptional changes associated with each metal. Results Comparative analysis identified subsets of differentially expressed transcripts both overlapping and unique to each metal. Application of gene ontology (GO) and transcription factor (TF) enrichment algorithms revealed a number of key biological processes perturbed by metal poisonings and the master transcriptional regulators mediating gene expression changes. Metal poisoning differentially activated biological processes associated with ribosome biogenesis, proteosomal degradation, and p53 signaling cascades, while repressing oxygen-generating pathways associated with amino acid and lipid metabolism. Despite appreciable effects on gene regulation, nickel poisoning did not induce any morphological alterations in male zebrafish organs and tissues. Histopathological effects of cobalt remained confined to the olfactory system, while chromium targeted the gills, pharynx, and intestinal mucosa. A number of enriched transcription factors mediated the observed gene response to metal poisoning, including known targets such as p53, HIF1α, and the myc oncogene, and novel

  3. An ultrastructural study of the stellate ganglion of the pig-tailed monkey (Macaca nemestrina).

    PubMed Central

    Leong, S K; Wong, W C

    1989-01-01

    The stellate ganglia of Macaca nemestrina were studied with the electron microscope, using the conventional and chromate-dichromate methods of aldehyde fixation. The principal neurons are multipolar and mostly mononucleated. They measure between 10 and 50 microns in their average somal diameters. The organelles of the perikaryon are arranged in perinuclear, intermediate and peripheral zones. Unusual organelles consisting of stacks of closely apposed paired membranes, with or without dense bodies studded on their surfaces, are encountered. Nuclear eccentricity is a regular feature of the neuron and the nuclear membrane shows a varying degree of invagination. All parts of the neurons are surrounded by satellite or Schwann cells though dendritic surfaces in direct contact with the basal lamina associated with the satellite cells are not uncommonly seen. Features peculiar to dendrites have been described. Structures resembling dendritic growth cones are present in abundance. Most synapses are axodendritic; axosomatic synapses are much less frequently encountered. While most synapses are of the simple type, complex types are also present. Desmosome-like junctional complexes exist between dendrites, dendrites and somata and axons and dendrites. Differences between Schwann cells of myelinated axons and those of myelinated axons and satellite cells have been noted. In addition to an abundance of macrophages, other connective tissue cells such as mast cells, fibroblasts and plasma cells are also present. Degenerative profiles observed include neuronal cell bodies and cell processes, especially dendrites. They are phagocytosed by the satellite cells and macrophages. The presence of degenerative profiles, chromatolytic neurons and structures resembling dendritic growth cones in the normal stellate ganglion has been discussed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Figs. 19

  4. 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.

  5. 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.

  6. 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

  7. [A case of chrome asthma induced by exposure to the stone cutter dust].

    PubMed

    Onizuka, Reiko; Tanabe, Kimiko; Nakayama, Yoshihisa; Fukuchi, Tetsuroh; Nakata, Kazunori; Hiki, Toshinobu

    2006-12-01

    The case of a forty-six year old, male patient with asthma caused by exposure to dust containing chrome is presented. When the patient was nineteen years old, he started working as a stonemason in a factory. He cut and ground stone with a stone-cutter to make statues and tombstones. Three years after staring to work, contact dermatitis was observed on his arms and hands. Within six years of work, he suffered from chronic coughing. After eight years, he experienced bronchial asthma attacks with wheezing and dyspnea. He had been exposed to dust for eight years before developing asthma. The symptoms increased gradually. He fell into severe asthma attacks causing unconsciousness and dyspnea. Several common therapies were not effective. The characteristics of his clinical course and occupational history suggested that the asthma must be caused by exposure to dust containing metal generated in the factory. Skin Patch Tests (SPT) were performed for cobalt, copper, iron, chrome, tin, and manganese salt. The result of the SPT indicated a strong positive result for potassium dichromate and positive for chromium sulfate, but did not show any indications in the control or for other metallic salt. Fluorescent X-ray analysis detected that chrome was present in the powder dust under the stone-cutter machine. However, the fluorescent X-ray analysis did not detect chrome in the stone materials. It was suggested that chrome must be contained in the metal dust generated from the steel cutter used to cut off and grind the stone. The metal component in the used cutter edge and the unused cutter edge were analyzed with electro-probe microanalyzer (EPMA). The result revealed that chrome was contained in the used, dull cutter edge and not in the new sharp cutter edge. Thus, the patient had been exposed to the dust containing chrome generated from part of the stainless steel of cutter. He had sensitized to chrome and this had caused the occupational chrome-asthma.

  8. Reflection hologram solar spectrum-splitting filters

    NASA Astrophysics Data System (ADS)

    Zhang, Deming; Gordon, Michael; Russo, Juan M.; Vorndran, Shelby; Escarra, Matthew; Atwater, Harry; Kostuk, Raymond K.

    2012-10-01

    In this paper we investigate the use of holographic filters in solar spectrum splitting applications. Photovoltaic (PV) systems utilizing spectrum splitting have higher theoretical conversion efficiency than single bandgap cell modules. Dichroic band-rejection filters have been used for spectrum splitting applications with some success however these filters are limited to spectral control at fixed reflection angles. Reflection holographic filters are fabricated by recording interference pattern of two coherent beams at arbitrary construction angles. This feature can be used to control the angles over which spectral selectivity is obtained. In addition focusing wavefronts can also be used to increase functionality in the filter. Holograms fabricated in dichromated gelatin (DCG) have the benefit of light weight, low scattering and absorption losses. In addition, reflection holograms recorded in the Lippmann configuration have been shown to produce strong chirping as a result of wet processing. Chirping broadens the filter rejection bandwidth both spectrally and angularly. It can be tuned to achieve spectral bandwidth suitable for spectrum splitting applications. We explore different DCG film fabrication and processing parameters to improve the optical performance of the filter. The diffraction efficiency bandwidth and scattering losses are optimized by changing the exposure energy, isopropanol dehydration bath temperature and hardening bath duration. A holographic spectrum-splitting PV module is proposed with Gallium Arsenide (GaAs) and silicon (Si) PV cells with efficiency of 25.1% and 19.7% respectively. The calculated conversion efficiency with a prototype hologram is 27.94% which is 93.94% compared to the ideal spectrum-splitting efficiency of 29.74%.

  9. 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

  10. 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

  11. 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

  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. 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.

  14. 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.

  15. 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.

  16. "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

  17. The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: the Yin/Yang actions of rhubarb.

    PubMed

    Zeng, Ling-na; Ma, Zhi-jie; Zhao, Yan-ling; Zhang, Lin-dong; Li, Rui-sheng; Wang, Jia-bo; Zhang, Ping; Yan, Dan; Li, Qi; Jiang, Bing-qian; Pu, Shi-biao; Lü, Yang; Xiao, Xiao-he

    2013-02-15

    Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed.

  18. 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.

  19. The Chromate-Inducible chrBACF Operon from the Transposable Element TnOtChr Confers Resistance to Chromium(VI) and Superoxide▿

    PubMed Central

    Branco, Rita; Chung, Ana Paula; Johnston, Tatiana; Gurel, Volkan; Morais, Paula; Zhitkovich, Anatoly

    2008-01-01

    Large-scale industrial use of chromium(VI) has resulted in widespread contamination with carcinogenic chromium(VI). The abilities of microorganisms to survive in these environments and to detoxify chromate require the presence of specific resistance systems. Here we report identification of the transposon-located (TnOtChr) chromate resistance genes from the highly tolerant strain Ochrobactrum tritici 5bvl1 surviving chromate concentrations of >50 mM. The 7,189-bp-long TnOtChr of the mixed Tn21/Tn3 transposon subfamily contains a group of chrB, chrA, chrC, and chrF genes situated between divergently transcribed resolvase and transposase genes. The chrB and chrA genes, but not chrF or chrC, were essential for establishment of high resistance in chromium-sensitive O. tritici. The chr promoter was strongly induced by chromate or dichromate, but it was completely unresponsive to Cr(III), oxidants, sulfate, or other oxyanions. Plasmid reporter experiments identified ChrB as a chromate-sensing regulator of chr expression. Induction of the chr operon suppressed accumulation of cellular Cr through the activity of a chromate efflux pump encoded by chrA. Expression of chrB, chrC, or chrF in an Escherichia coli sodA sodB double mutant restored its aerobic growth in minimal medium and conferred resistance to superoxide-generating agents menadione and paraquat. Nitroblue tetrazolium staining on native gels showed that ChrC protein had superoxide dismutase activity. TnOtChr appears to represent a mobile genetic system for the distribution of the chromate-regulated resistance operon. The presence of three genes protecting against superoxide toxicity should provide an additional survival advantage to TnOtChr-containing cells in the environments with multiple redox-active contaminants. PMID:18776016

  20. Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes evaluated by the single cell gel electrophoresis (comet assay).

    PubMed

    Trzeciak, A; Kowalik, J; Małecka-Panas, E; Drzewoski, J; Wojewódzka, M; Iwaneńko, T; Błasiak, J

    2000-01-01

    Hexavalent chromium compounds are well-recognized carcinogens. They easily penetrate the cell membrane and are reduced inside the cell to their trivalent form, which is supposed to react directly with DNA. Chromium is present in some workplaces as well as in water resources and food chain, so it can interact with the mucosa of the gastrointestinal tract. In order to elucidate the genotoxic potency of chromium in human gastric mucosa (GM) cells, the DNA-damaging effect of potassium dichromate (K2Cr2O7) was investigated using alkaline single cell gel electrophoresis (comet assay). Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach. Parallel test with human peripheral blood lymphocytes was also performed. Both types of cells were incubated at 37 degrees C with 1.6 mM of K2Cr2O7 for 1 h and after washing, were placed in a chromium-free medium to examine DNA repair. Alkaline single cell gel electrophoresis (comet assay) was used to assess DNA damage and repair. Chromium introduced a damage to DNA both in the GM cells and lymphocytes. The effect induced by K2Cr2O7 in GM cells was comparable with that caused in the lymphocytes. Treated cells were able to recover within a 60-min incubation in a chromium-free medium at 37 degrees C. The results obtained indicate that hexavalent chromium compounds, which may be found in the diet, can interact directly with DNA of the mucosa of the stomach. PMID:11208279

  1. 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

  2. Phosphor coating technique with slurry method in application of white LED

    NASA Astrophysics Data System (ADS)

    Hou, Bin; Rao, Haibo; Li, Junfei

    2008-03-01

    White light was realized through combining a cerium-doped yttrium aluminum garnet (YAG:Ce 3+) phosphor with a gallium nitride (GaN)-based blue LED. In order to coat the high quality yellow phosphor layer on a GaN chip, the slurry coating technique was focused on because of the speed and coating uniformity. The slurry method is based on a phosphor suspension in a water-soluble photoresist, which is consisted of polyvinyl alcohol (PVA) and ammonium dichromate (ADC). And self-exposure of LED chip was employed as an optimized exposing way to make the photoresist crosslinking. The properties of the phosphor layer in terms of profile, light intensity and uniformity and spectrum were investigated. To improve the qualities of phosphor layer some additives were introduced such as polyvinyl acetate (PVAc) for improving adhesion strength, dispersants and defoamer for uniformity. The thickness of phosphor layer was controlled by altering the time of exposure under UV or blue light. The phosphor pattern with clear margins according to the mask and conformal shape were achieved in different substrates either glasses or LED chips. The white light output of high intensity and good uniformity due to the optimized thickness of phosphor layer were achieved. A defect of photoresist is that the ADC would absorb parts of blue light emitted from LED chip and quench light output, especially in the high concentration, some approaches can be employed to diminish and avoid this defect, such as reduce the ADC's concentration, and find new photosensitizer to replace the ADC.

  3. 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

  4. Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium.

    PubMed Central

    Pedersen, P; Thomsen, E; Stern, R M

    1983-01-01

    The replica plating method as developed by Lederberg has been used to differentiate between "true" and "false" histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of "false" revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between "true" and "false" revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting "revertant" colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6357773

  5. "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

  6. 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

    2016-01-01

    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.

  7. Potential contributions of asphalt and coal tar to black carbon quantification in urban dust, soils, and sediments

    NASA Astrophysics Data System (ADS)

    Yang, Yaning; Mahler, Barbara J.; Van Metre, Peter C.; Ligouis, Bertrand; Werth, Charles J.

    2010-12-01

    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 (Cr 2O 7) 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 Cr 2O 7 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 Cr 2O 7 oxidation and CTO-375. The reference asphalt is resistant to Cr 2O 7 oxidation but not to CTO-375, and the reference coal tar is resistant to both Cr 2O 7 oxidation and CTO-375. These results indicate that coal tar and/or asphalt can contribute to BC measurements in samples from urban areas using Cr 2O 7 oxidation or CTO-375, and caution is advised when interpreting BC measurements made with these methods.

  8. 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.

  9. 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.

  10. Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater.

    PubMed

    Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N

    2012-11-01

    A novel reactive electrochemical flow system consisting of an iron anode and a 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 protons 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 the 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 in 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.

  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. Effect of Iron on Rheological Properties of HPG8

    NASA Astrophysics Data System (ADS)

    Chevrel, M. O.; Hess, K.; Dingwell, D. B.

    2010-12-01

    The influence of iron on the structure and properties of magmatic melts remains controversial. Simple system investigations indicate an as yet insufficiently parameterized influence of the oxidation state of iron on the rheology and other properties of silicate melts. Previously, two different simple Fe-bearing systems have been studied: an iron-bearing sodium disilicate and anorthite-diopside eutectic with different amounts of iron up to 30 wt % FeO. It has been shown that iron decreases the viscosity of the melt and the increase of the Fe2+/ΣFe ratio reduces non-linearly the viscosity. This last effect is a lot more efficient for polymerized melt than for depolymerized melts if Fe2+ plays a role as network modifier and Fe3+as network former. Here, the compositional range has been extended to Fe-bearing haplogranite (HPG8), as analogue to fully polymerized volcanic melt. The viscosity has been investigated at 1atm over a large range of temperatures. Low viscosity measurements were performed with a concentric cylinder assembly and the super-cooled melt viscosities with micro-penetration method. Calorimetric glass transition temperatures have been measured with a Differential Scanning Calorimeter and the ratio Fe2+/ΣFe was measured by potassium dichromate titration. Our first results indicate that in the super-liquidus state (1500°C) the addition of iron decreases significantly the viscosity of HPG8 (10 wt. % Fe2O3 involves a viscosity decrease of 1.28 log Pa s). In respect to other oxides, at low contents, Fe behaves like Ca and at higher contents (20 wt. %) it tends to have a stronger influence by decreasing the viscosity such as Mg and Ca. In contrast, at the glass transition the present of 5 wt. % Fe has almost no influence on the viscosity, however, 10 wt. % Fe will decrease the viscosity by about 2 log units (acting like Mg). Considering Fe3+ as a network former and Fe2+ a network modifier, whatever the amount of Fe we add the NBO/T remains zero. Therefore

  13. 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

  14. Statistical design of experiments as a tool for optimizing the batch conditions to Cr(VI) biosorption on Araucaria angustifolia wastes.

    PubMed

    Brasil, Jorge L; Ev, Ricardo R; Milcharek, Caroline D; Martins, Lucas C; Pavan, Flavio A; dos Santos, Araci A; Dias, Silvio L P; Dupont, Jairton; Zapata Noreña, Caciano P; Lima, Eder C

    2006-05-20

    In order to reduce the total number of experiments for achieving the best conditions for Cr(VI) uptake using Araucaria angustifolia (named pinhão) wastes as a biosorbent, three statistical design of experiments were carried out. A full 2(4) factorial design with two blocks and two central points (20 experiments) was experimented (pH, initial metallic ion concentration-C(o), biosorbent concentration-X and time of contact-t), showing that all the factors were significant; besides, several interactions among the factors were also significant. These results led to the performance of a Box-Behnken surface analysis design with three factors (X, C(o) and t) and three central points and just one block (15 experiments). The performance of these two statistical designs of experiments led to the best conditions for Cr(VI) biosorption on the pinhão wastes using a batch system, where: pH 2.0; C(o) = 1200 mg l(-1) Cr(VI); X = 1.5 g l(-1) of biosorbent; t = 8 h. The maximum Cr(VI) uptake in these conditions was 125 mg g(-1). After evaluating the best Cr(VI) biosorption conditions on pinhão wastes, a new Box-Behnken surface analysis design was employed in order to verify the effects of three concomitant ions (Cl(-), NO(3)(-) and PO(4)(3-)) on the biosorption of Cr(VI) as a dichromate on the biosorbent (15 experiments). These results showed that the tested anions did not show any significant effect on the Cr(VI) uptake by pinhão wastes. In order to evaluate the pinhão wastes as a biosorbent in dynamic system, a glass column was fulfilled with pinhão wastes (4.00 g) as biosorbent, and it was fed with 25.0 mg l(-1) Cr(VI) at pH 2.0 and 2.5 ml min(-1). The breakpoint was attained when concentrations of effluent of the column attained the value of 0.05 mg l(-1) Cr(VI) using 5550 ml of the metallic ion solution. In these conditions, the biosorbent was able to remove completely Cr(VI) from aqueous solution with a ratio of Cr(VI) effluent volume/biosorbent volume of 252.3.

  15. Changes of soil organic matter and microbial activity in irrigated and non irrigated olive groves

    NASA Astrophysics Data System (ADS)

    Kavvadias, Victor; Papadopoulou, Maria; Theocharopoulos, Sideris; Vavoulidou, Evagelia; Doula, Maria; Reppas, Spiros

    2014-05-01

    The implementation of olive cultivation techniques in Greece has not been systematically tested under the prevailing Mediterranean conditions. A LIFE+ project was initiated (oLIVE-CLIMA; LIFE 11/ENV/000942) aiming to introduce new management practices in olive tree crops that lead to increased carbon dioxide uptake by plants as well as carbon sequestration from the atmosphere and reverse the trend of soil organic matter decline, erosion and desertification. This paper presents data on soil organic matter and microbial activity from a soil campaign in a pilot region in Greece, and particularly in the area of Chora, prefecture of Messinia, South west Peloponnese. The soil campaign took place during the period December 2012-February 2013. Twelve soil parcels of olive groves were selected (6 irrigated and 6 rainfed) and in each soil parcel six composite soil samples were taken from 0-10 cm depth at equal intervals along a straight line of the trunk of the tree to the middle of the distance from the nearest tree of the next tree series. The first three samples were under olive tree canopy. An additional composite sample was taken at depth of 10-40 cm. Soil samples were analyzed for soil physicochemical and biological properties. In this study results for total organic carbon (TOC), soil basal microbial respiration (BR), microbial biomass C (MB-C) from the region of Messinia, are presented. Organic matter was determined by dichromate oxidation. The microbial activity was measured by the amount of CO2 evolution, while microbial biomass C was determined by substrate-induced respiration, after the addition of glucose. The results showed considerable differences in TOC, BR and MB-C associated with the sampling position and soil depth. The higher TOC, BR and MB-C values, in most cases, were determined in samples taken from points under the canopy, but not close to the tree trunk compared to the sampling points outside the canopy. This indicates the positive effect of

  16. 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

  17. Monocarbaborane anion chemistry. [COOH], [CH2OH] and [CHO] units as functional groups on ten-vertex monocarbaborane anionic compounds.

    PubMed

    Franken, Andreas; Carr, Michael J; Clegg, William; Kilner, Colin A; Kennedy, John D

    2004-11-01

    B(10)H(14) reacts with para-C(6)H(4)(CHO)(COOH) in aqueous KOH solution to give the [nido-6-CB(9)H(11)-6-(C(6)H(4)-para-COOH)](-) anion 1, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB(9)H(9)-2-(C(6)H(4)-para-COOH)](-) anion 2. Upon heating, anion 2 rearranges to form the [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-COOH)](-) anion 3. Similarly, B(10)H(14) with glyoxylic acid OHCCOOH in aqueous KOH gives the [arachno-6-CB(9)H(13)-6-(COOH)](-) anion 4, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB(9)H(9)-2-(COOH)](-) anion 5. Upon heating, anion 5 rearranges to give the [closo-1-CB(9)H(9)-1-(COOH)](-) anion 6. Reduction of the [COOH] anions 3 and 6 with diisobutylaluminium hydride gives the [CH(2)OH] hydroxy anions [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CH(2)OH)](-) and [closo-1-CB(9)H(9)-1-(CH(2)OH)](-) 8 respectively. The [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CH(2)OH)](-) anion 7 can also be made via isomerisation of the [closo-2-CB(9)H(9)-2-(C(6)H(4)-para-CH(2)OH)](-) anion 9, in turn obtained from the [nido-6-CB(9)H(11)-6-(C(6)H(4)-para-CH(2)OH)](-) anion 10, which is obtained from the reaction of B(10)H(14) with terephthaldicarboxaldehyde, C(6)H(4)-para-(CHO)(2), in aqueous KOH solution. Oxidation of the hydroxy anions 7 and 8 with pyridinium dichromate gives the aldehydic [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CHO)](-) anion 11 and the aldehydic [closo-1-CB(9)H(9)-1-(CHO)](-) anion 12 respectively, characterised as their 2,4-dinitrophenylhydrazone derivatives, the [closo-1-CB(9)H(9)-1-C(6)H(4)-para-CH=N-NHC(6)H(3)(NO(2))(2)](-) anion 13 and the [closo-1-CB(9)H(9)-1-CH=N-NHC(6)H(3)(NO(2))(2)](-) anion respectively.

  18. 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

  19. 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

  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