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  1. ANALISIS KONSENTRASI MERKURI (Hg DAN CADMIUM (Cd DI MUARA SUNGAI PORONG SEBAGAI AREA BUANGAN LIMBAH LUMPUR LAPINDO

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    R Rachmawatie

    2009-10-01

    Full Text Available Tujuan riset ini adalah untuk meneliti konsentrasi Merkuri ( Hg dan Cadmium ( Cd di  muara Sungai Porong serta menentukan tingkat pencemaran logam berat di area tersebut. Analisa statistic yang digunakan adalah  ANOVA  dan analisis regresi yang digunakan untuk menguji hubungan logam berat yang terdeteksi dengan parameter penunjang. Hasil penelitian menunjukkan konsentrasi Cd telah melewati batasan normal di area muara. Disamping itu, Merkuri (Hg tidak terdeteksi. Rata-Rata konsentrasi Cd dari 9 stasiun adalah 0,025 - 0,075 mg/liter. Hasil ANOVA menunjukkan rata-rata konsentrasi Cadmium (Cd dari seluruh stasiun pengamatan  adalah berbeda nyata (p < 0,05. Selanjutnya, analisis regresi menunjukkan bahwa model regresi dapat menjelaskan hubungan konsentrasi logam berat Cadmium (Cd dengan beberapa parameter kualitas air  ( R2 < 70%. Kata Kunci :  Cadmium, Merkuri, muara Sungai Porong

  2. ANALISIS KONSENTRASI MERKURI (Hg) DAN CADMIUM (Cd) DI MUARA SUNGAI PORONG SEBAGAI AREA BUANGAN LIMBAH LUMPUR LAPINDO

    OpenAIRE

    R Rachmawatie; Zainul Hidayah; Indah Wahyuni Abida

    2009-01-01

    Tujuan riset ini adalah untuk meneliti konsentrasi Merkuri ( Hg) dan Cadmium ( Cd) di  muara Sungai Porong serta menentukan tingkat pencemaran logam berat di area tersebut. Analisa statistic yang digunakan adalah  ANOVA  dan analisis regresi yang digunakan untuk menguji hubungan logam berat yang terdeteksi dengan parameter penunjang. Hasil penelitian menunjukkan konsentrasi Cd telah melewati batasan normal di area muara. Disamping itu, Merkuri (Hg) tidak terdeteksi. Rata-Rata konsentrasi Cd d...

  3. Mercury cadmium telluride (HgCdTe) passivation by advanced thin conformal Al2O3 films

    Science.gov (United States)

    Fu, Richard; Pattison, James; Chen, Andrew; Nayfeh, Osama

    2012-06-01

    HgCdTe passivation process must be performed at low temperature in order to reduce Hg depletion. Low temperature plasma enhanced atomic layer deposition (PE-ALD) is an emerging deposition technology for thin highly conformal films to meet the demand. Room temperature PE-ALD Al2O3 film's passivation on HgCdTe has been studied. Conformal film was investigated through SEM images of the Al2O3 film deposited onto high aspect ratio features dry etched into HgCdTe. Minority carrier lifetime was measured and compared by photoconductive decay transients of HgCdTe before and after deposition. Room temperature ALD Al2O3 film increased the minority carrier lifetime of HgCdTe.

  4. Chemical substitution of Cd ions by Hg in CdSe nanorods and nanodots: Spectroscopic and structural examination

    Energy Technology Data Exchange (ETDEWEB)

    Prudnikau, Anatol [Institute for Physico-Chemical Problems, Belarussian State University, 220030 Minsk (Belarus); Artemyev, Mikhail, E-mail: m_artemyev@yahoo.com [Institute for Physico-Chemical Problems, Belarussian State University, 220030 Minsk (Belarus); Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute, 31 Kashirskoe sh., 115409 Moscow (Russian Federation); Molinari, Michael; Troyon, Michel [Universite de Reims Champagne-Ardenne, 51100 Reims (France); Sukhanova, Alyona; Nabiev, Igor [Universite de Reims Champagne-Ardenne, 51100 Reims (France); Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute, 31 Kashirskoe sh., 115409 Moscow (Russian Federation); Baranov, Alexandr V.; Cherevkov, Sergey A.; Fedorov, Anatoly V. [Saint-Petersburg State University of Information Technologies, Mechanics and Optics, St.-Petersburg 197101 (Russian Federation)

    2012-06-05

    Highlights: Black-Right-Pointing-Pointer We studied cadmium-by-mercury chemical substitution in CdSe nanocrystals. Black-Right-Pointing-Pointer Zinc blende CdSe quantum dots can be easily converted to isostructural Cd{sub x}Hg{sub 1-x}Se. Black-Right-Pointing-Pointer Wurtzite CdSe QDs require longer time to convert to a zinc blende Cd{sub x}Hg{sub 1-x}Se. Black-Right-Pointing-Pointer Wurtzite CdSe nanorods transform to nanoheterogeneous luminescent Cd{sub x}Hg{sub 1-x}Se rods. - Abstract: The chemical substitution of cadmium by mercury in colloidal CdSe quantum dots (QDs) and nanorods has been examined by absorption, photoluminescence and Raman spectroscopy. The crystalline structure of original CdSe QDs used for Cd/Hg substitution (zinc blende versus wurtzite) shows a strong impact on the optical and structural properties of resultant Cd{sub x}Hg{sub 1-x}Se nanocrystals. Substitution of Cd by Hg in isostructural zinc blende CdSe QDs converts them to ternary Cd{sub x}Hg{sub 1-x}Se zinc blende nanocrystals with significant NIR emission. Whereas, the wurtzite CdSe QDs transformed first to ternary nanocrystals with almost no emission followed by slow structural reorganization to a NIR-emitting zinc blende Cd{sub x}Hg{sub 1-x}Se QDs. CdSe nanorods with intrinsic wurtzite structure show unexpectedly intense NIR emission even at early Cd/Hg substitution stage with PL active zinc blende Cd{sub x}Hg{sub 1-x}Se regions.

  5. HgTe-CdTe SUPERLATTICES

    OpenAIRE

    Smith, D; Mcgill, T.

    1984-01-01

    We report on a theoretical study of the electronic properties of HgTe-CdTe superlattices. The band gap as a function of layer thickness, effective masses normal to the layer plane and tunneling length are compared to the corresponding (Hg, Cd)Te alloys. We find that the superlattice possesses a number of properties that may make it superior to the corresponding alloy as an infrared material.

  6. Ion Beam Nanostructuring of HgCdTe Ternary Compound

    Science.gov (United States)

    Smirnov, Aleksey B.; Savkina, Rada K.; Udovytska, Ruslana S.; Gudymenko, Oleksandr I.; Kladko, Vasyl P.; Korchovyi, Andrii A.

    2017-05-01

    Systematic study of mercury cadmium telluride thin films subjected to the ion beam bombardment was carried out. The evolution of surface morphology of (111) Hg1 - x Cd x Te ( x 0.223) epilayers due to 100 keV B+ and Ag+ ion irradiation was studied by AFM and SEM methods. X-ray photoelectron spectroscopy and X-ray diffraction methods were used for the investigation of the chemical compound and structural properties of the surface and subsurface region. It was found that in the range of nanoscale, arrays of holes and mounds on Hg0.777Cd0.223Te (111) surface as well as the polycrystalline Hg1 - x Cd x Te cubic phase with alternative compound ( x 0.20) have been fabricated using 100 keV ion beam irradiation of the basic material. Charge transport investigation with non-stationary impedance spectroscopy method has shown that boron-implanted structures are characterized by capacity-type impedance whereas for silver-implanted structures, an inductive-type impedance (or "negative capacitance") is observed. A hybrid system, which integrates the nanostructured ternary compound (HgCdTe) with metal-oxide (Ag2O) inclusions, was fabricated by Ag+ ion bombardment. The sensitivity of such metal-oxide-semiconductor hybrid structure for sub-THz radiation was detected with NEP 4.5 × 10-8 W/Hz1/2at ν ≈ 140 GHz and 296 K without amplification.

  7. HgCdTe barrier infrared detectors

    Science.gov (United States)

    Kopytko, M.; Rogalski, A.

    2016-05-01

    In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar barriers. This idea has been also implemented in HgCdTe ternary material system. However, the implementation of this detector structure in HgCdTe material system is not straightforward due to the existence of a valence band discontinuity (barrier) at the absorber-barrier interface. In this paper we present status of HgCdTe barrier detectors with emphasis on technological progress in fabrication of MOCVD-grown HgCdTe barrier detectors achieved recently at the Institute of Applied Physics, Military University of Technology. Their performance is comparable with state-of-the-art of HgCdTe photodiodes. From the perspective of device fabrication their important technological advantage results from less stringent surface passivation requirements and tolerance to threading dislocations.

  8. MBE HgCdTe heterostructure detectors

    Science.gov (United States)

    Schulman, Joel N.; Wu, Owen K.

    1990-01-01

    HgCdTe has been the mainstay for medium (3 to 5 micron) and long (10 to 14 micron) wavelength infrared detectors in recent years. Conventional growth and processing techniques are continuing to improve the material. However, the additional ability to tailor composition and placement of doped layers on the tens of angstroms scale using molecular beam epitaxy (MBE) provides the opportunity for new device physics and concepts to be utilized. MBE-based device structures to be discussed here can be grouped into two categories: tailored conventional structures and quantum structures. The tailored conventional structures are improvements on familiar devices, but make use of the ability to create layers of varying composition, and thus band gap, at will. The heterostructure junction can be positioned independently of doping p-n junctions. This allows the small band gap region in which the absorption occurs to be separated from a larger band gap region in which the electric field is large and where unwanted tunneling can occur. Data from hybrid MBE/liquid phase epitaxy (LPE)/bulk structures are given. Quantum structures include the HgTe-CdTe superlattice, in which the band gap and transport can be controlled by alternating thin layers (tens of angstroms thick) of HgTe and CdTe. The superlattice has been shown to exhibit behavior which is non-alloy like, including very high hole mobilities, two-dimensional structure in the absorption coefficient, resonant tunneling, and anisotropic transport.

  9. Distribution and age-related bioaccumulation of lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) in tissues of common carp (Cyprinus carpio) and European catfish (Sylurus glanis) from the Buško Blato reservoir (Bosnia and Herzegovina).

    Science.gov (United States)

    Has-Schön, Elizabeta; Bogut, Ivan; Vuković, Rosemary; Galović, Dalida; Bogut, Ante; Horvatić, Janja

    2015-09-01

    The purpose of this study was to quantify the bioaccumulation of Pb, Hg, Cd, and As in tissues of carp (Cyprinus carpio) and catfish (Silurus glanis) from Buško Blato in Bosnia and Herzegovina. Arsenic concentrations were below the Maximal Admissible Concentration (MAC) for Croatia and other countries. Mercury concentrations were below 1 mg kg(-1), but in most muscle samples of both species and all catfish liver samples, the values were higher than 0.5 mg kg(-1) (higher than the MAC for many countries including Croatia). Lead concentrations were higher than 1 mg kg(-1) (the MAC for Croatia) in most muscle samples; all kidney and most catfish liver samples also exceeded 1 mg kg(-1). Cadmium concentrations in all tissues, other than the gonads, were higher than 0.1 mg kg(-1) (MAC for Croatia), with the highest concentrations found in the kidneys. The only gender difference was found in carp, where a 68.4% higher concentration of As was found in the fry compared to the milt (P<0.05). Concentrations of all of the elements were higher in catfish compared to carp for most tissues. Significant correlations were found between all of the elements in the muscles and the liver of carp. In catfish, the muscles were the only tissue in which multiple correlations were found. Linear positive correlations with age and body mass were demonstrated for the concentrations of all heavy metals for all tissues except the gonads in both fish species. We concluded that significant heavy metal accumulation in carp and a catfish tissues correlates with age and body mass; bioaccumulation is species- and tissue-specific and is different for each element.

  10. An investigation for the HgCdTe cleaning process

    Science.gov (United States)

    Lan, Tian-Yi; Wang, Nili; Zhao, Shuiping; Liu, Shi-Jia; Li, Xiang-Yang

    2014-11-01

    A new cleaning process for HgCdTe was designed - which used the improved SC-1,SC-2 and Br2- C2H5OH solutions as the main cleaning fluid and applied mega sound waves in the cleaning process. By analyzing the test results carried out on the HgCdTe surface, it was found that the material of HgCdTe for the application of new cleaning process was better than the one for the application of conventional cleaning process in the minority carrier lifetime, residual organic contamination, responsivity and specific detectivity.

  11. Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

    Energy Technology Data Exchange (ETDEWEB)

    Gajdosechova, Zuzana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Brownlow, Andrew [SAC Wildlife Unit, Inverness (United Kingdom); Cottin, Nicolas T.; Fernandes, Mariana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Read, Fiona L. [Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA (United Kingdom); Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M. [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

    2016-03-01

    The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

  12. Temperature-driven massless Kane fermions in HgCdTe crystals

    Science.gov (United States)

    Teppe, F.; Marcinkiewicz, M.; Krishtopenko, S. S.; Ruffenach, S.; Consejo, C.; Kadykov, A. M.; Desrat, W.; But, D.; Knap, W.; Ludwig, J.; Moon, S.; Smirnov, D.; Orlita, M.; Jiang, Z.; Morozov, S. V.; Gavrilenko, V. I.; Mikhailov, N. N.; Dvoretskii, S. A.

    2016-08-01

    It has recently been shown that electronic states in bulk gapless HgCdTe offer another realization of pseudo-relativistic three-dimensional particles in condensed matter systems. These single valley relativistic states, massless Kane fermions, cannot be described by any other relativistic particles. Furthermore, the HgCdTe band structure can be continuously tailored by modifying cadmium content or temperature. At critical concentration or temperature, the bandgap collapses as the system undergoes a semimetal-to-semiconductor topological phase transition between the inverted and normal alignments. Here, using far-infrared magneto-spectroscopy we explore the continuous evolution of band structure of bulk HgCdTe as temperature is tuned across the topological phase transition. We demonstrate that the rest mass of Kane fermions changes sign at critical temperature, whereas their velocity remains constant. The velocity universal value of (1.07+/-0.05) × 106 m s-1 remains valid in a broad range of temperatures and Cd concentrations, indicating a striking universality of the pseudo-relativistic description of the Kane fermions in HgCdTe.

  13. Removal of Cd (II and Hg(II by chelating resin Chelex-100

    Directory of Open Access Journals (Sweden)

    Afaf Amara-Rekkab

    2015-03-01

    Full Text Available A sensitive, simple method for the determination of amounts of mixture of Hg2+and Cd2+ by spectrophotometry was described based on the formation of the Hg2+- Cd2+- PAN complex in water media. Optimal conditions such as reagent amounts, and pH for the Hg2+- Cd2+ determination were reported. It was found that the 2:1 PAN- Hg2+- Cd2+ complex dominate at pH 13.0. In another hand, the sorption of mixture mercury (II and cadmium (II from aqueous medium on a chelating resin Chelex 100 was studied in batch mode. Since the extraction kinetic was obtained, with a mixture of 0.1 g of resin and 5 mL of mixture at 1 mmol/L of initial concentration, extraction equilibrium was reached within 20 min of mixing. The influence of some parameters such as initial mixture ions concentrations, initial pH of aqueous solution, ion strength and the amounts of resin have been studied at fixed temperature (20±1°C. The optimum pH value level for quantitative sorption was up to 2.6. The best performance obtained was 97.1% of extraction yield equivalent to 15.65 mg/g of resin. The pseudo-first- order, pseudo-second-order models and the intra-particle diffusion model were used to describe the kinetic data and rate constants were evaluated.

  14. Dislocation reduction in HgCdTe grown on CdTe/Si

    Science.gov (United States)

    Wijewarnasuriya, Priyalal S.

    2016-05-01

    Bulk-grown CdZnTe (Zn = 3%) substrates are the natural choice for HgCdTe epitaxy since it is lattice matched to long wave LW-HgCdTe alloy. However, lack of large area CdZnTe substrates, high production costs, and more importantly, the difference in thermal expansion coefficients between CdZnTe and silicon Read out Integrated Circuits (ROIC) are some of the inherent drawbacks of CdZnTe substrates. Consequently, Hg1-xCdxTe detectors fabricated on silicon substrates are an attractive alternative. Recent developments in the molecular beam epitaxy (MBE) buffer layer growth technology on Si substrates has revolutionized the HgCdTe research and offered a new dimension to HgCdTe-based IR technology. Si substrates provide advantages in terms of relatively large area (3 to 6-inch diameter is easily obtained) compared to CZT substrate materials, durability during processing, and reliability to thermal cycling. Innovations in Si-based composite substrates made it possible to fabricate very large-format IR arrays that offer higher resolution, low-cost arrays and more dies per wafer. Between Si substrates and HgCdTe has large lattice mismatch of 19%. This leads to dislocation densities of low-107 cm-2 for optimal growth of HgCdTe on silicon-based substrates as compared to the mid-104 cm-2 dislocation density of HgCdTe grown on CdZnTe. This paper present dislocation reduction by two orders of magnitude using thermal cycle anneal under Hg environment on HgCdTe grown on Si substrates and as well as defect reduction in Cd(Se)Te buffer layers grown on Si Substrates.

  15. Comparative study of Hg xCd 1-xTe films grown on CdTe thin films previously deposited from two different techniques

    Science.gov (United States)

    Ali, A.; Abbas Shah, N.; Maqsood, A.

    2009-04-01

    High quality cadmium telluride (CdTe) thin films were grown on glass substrates with two different techniques, two evaporation source (TES) and closed space sublimation (CSS). Further to the above mercury telluride (HgTe) was then deposited by using single source on both CdTe thin films for obtaining Hg xCd 1-xTe samples. The crystalline structure of the Hg xCd 1-xTe sample grown from CSS-CdTe showed the preferential (1 1 1) orientation with smoother and larger grain size than those of TES-CdTe. The optical transmission for TES-CdTe sample was above 90% in the 1000-1500 nm range whereas it was significantly below 80% for CSS-CdTe sample. The optical transmission for TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe was ˜60%. The resistivity at room temperature of TES-CdTe and CSS-CdTe was ˜3.33×10 9 Ω cm and ˜2.20×10 8 Ω cm, respectively, while the resistivity of TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe samples was ˜1.73 Ω cm and ˜5.34×10 5 Ω cm, respectively. The comparative study of ternary compound prepared with the above techniques has been carried out for the first time.

  16. Doping and Diffusion in HgCdTe

    Science.gov (United States)

    1991-01-28

    In’i, -InT. Te - 1.8 ( - 3 .5 )h ( + 2.9 - 6/) TeT1’- Tej . 4 Hg rich HgCdTe Hg - 1.8 + 1.2 + 1.4 - 2p H - ’g, - H g j.. ’TI - tetrahedral position...A. Anderson, Appl. Phys. Lett. 53, 11.81 (1988). B. D. Patterson, Rev. Mod. Phys. 60, 69 (1988). 60 V. A. Singh , C. Weigel, J. W. Corbett, and L. M

  17. Diffusion Mechanism for Arsenic in Intrinsic and Extrinsic Conditions in HgCdTe

    Science.gov (United States)

    Grenouilloux, T.; Ferron, A.; Péré-Laperne, N.; Mathiot, D.

    2017-09-01

    Due to its low diffusivity and high activation rate, arsenic has become the dopant of choice in p/n HgCdTe high operating temperature technology. Its diffusion mechanism, however, remains imprecise. In this work, arsenic diffusion was studied in molecular beam epitaxy HgCdTe structures consisting of alternatively As-doped and intrinsic layers grown on a CdZnTe substrate. The diffusion coefficient of As was extracted from secondary ion mass spectroscopy concentration profiles. Annealings were performed for different temperatures, mercury partial pressures ( P Hg), annealing times and cadmium atomic fractions. Fermi-level effect on diffusion was observed, indicating extrinsic conditions for diffusion at high As concentration. Based on the variation of As diffusivity with P Hg and As concentration, we propose that As diffusion occurs on both II and VI sublattices. Our results are consistent with the fact that AsVI diffusion is assisted by the Te interstitial, introducing donor levels in the bandgap, while AsII diffusion is assisted by the cation vacancy.

  18. Crystal Growth of Solid Solution HgCdTe Alloys

    Science.gov (United States)

    Lehoczky, Sandor L.

    1997-01-01

    The growth of homogenous crystals of HgCdTe alloys is complicated by the large separation between their liquidus and solidus temperatures. Hg(1-x)Cd(x)Te is representative of several alloys which have electrical and optical properties that can be compositionally tuned for a number of applications. Limitations imposed by gravity during growth and results from growth under reduced conditions are described. The importance of residual accelerations was demonstrated by dramatic differences in compositional distribution observed for different attitudes of the space shuttle that resulted in different steady acceleration components.

  19. 640 X 480 Pace HgCdTe FPA

    Science.gov (United States)

    Kozlowski, Lester J.; Bailey, Robert B.; Cabelli, Scott A.; Cooper, Donald E.; McComas, Gail D.; Vural, Kadri; Tennant, William E.

    1992-12-01

    A hybrid HgCdTe 640 X 480 infrared (IR) focal plane array (FPA) that meets the sensitivity, resolution, and field-of-view requirements of high-performance medium wavelength infrared (MWIR) imaging systems has been developed. The key technology making this large, high sensitivity device producible is the epitaxial growth of HgCdTe on a CdTe-buffered, sapphire substrate (referred to as PACE, for Producible Alternative to CdTe for Epitaxy; PACE-I refers to sapphire). The device offers TV resolution with excellent sensitivity at temperatures below 120 K. Mean NE(Delta) T as low as 13 mK has been achieved at operating temperatures nonuniformity compensation.

  20. Theoretical Study of Midwave Infrared HgCdTe nBn Detectors Operating at Elevated Temperatures

    Science.gov (United States)

    Akhavan, Nima Dehdashti; Jolley, Gregory; Umana-Membreno, Gilberto A.; Antoszewski, Jarek; Faraone, Lorenzo

    2015-09-01

    We report a theoretical study of mercury cadmium telluride (HgCdTe) unipolar n-type/barrier/ n-type (nBn) detectors for midwave infrared (MWIR) applications at elevated temperatures. The results obtained indicate that the composition, doping, and thickness of the barrier layer in MWIR HgCdTe nBn detectors can be optimized to yield performance levels comparable with those of ideal HgCdTe p- n photodiodes. It is also shown that introduction of an additional barrier at the back contact layer of the detector structure (nBnn+) leads to substantial suppression of the Auger generation-recombination (GR) mechanism; this results in an order-of-magnitude reduction in the dark current level compared with conventional nBn or p- n junction-based detectors, thus enabling background-limited detector operation above 200 K.

  1. Phytoremediation of Hg and Cd from industrial effluents using an aquatic free floating macrophyte Azolla pinnata.

    Science.gov (United States)

    Rai, Prabhat Kumar

    2008-01-01

    The level of heavy metal pollution in Singrauli, an industrial region in India, was assessed and the phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae), was observed to purify waters polluted by two heavy metals, i.e., mercury (Hg) and cadmium (Cd) under a microcosm condition. Azolla pinnata is endemic to India and is an abundant and easy-growing free-floating water fern usually found in the rice fields, polluted ponds, and reservoirs of India. The fern was grown in 24 40-L aquariums containing Hg2+ and Cd2+ ions each in concentrations of 0.5, 1.0, and 3.0 mgL(-1) during the course of this study. The study revealed an inhibition of Azolla pinnata growth by 27.0-33.9% with the highest in the presence of Hg (II) ions at 0.5 mgL(-1) in comparison to the control After 13 days of the experiment, metal contents in the solution were decreased up to 70-94%. In the tissues of Azolla pinnata, the concentration of selected heavy metals during investigation was recorded between 310 and 740 mgKg(-1) dry mass, with the highest levelfoundfor Cd (II) treatment at 3.0 mgL(-1) containing a metal solution.

  2. Interactions between photoexcited NIR emitting CdHgTe quantum dots and graphene oxide

    Science.gov (United States)

    Jagtap, Amardeep M.; Varade, Vaibhav; Konkena, Bharathi; Ramesh, K. P.; Chatterjee, Abhijit; Banerjee, Arup; Pendyala, Naresh Babu; Koteswara Rao, K. S. R.

    2016-02-01

    Hydrothermally grown mercury cadmium telluride quantum dots (CdHgTe QDs) are decorated on graphene oxide (GO) sheets through physisorption. The structural change of GO through partial reduction of oxygen functional groups is observed with X-ray photoelectron spectroscopy in GO-QDs composites. Raman spectroscopy provides relatively a small change (˜1.1 times) in D/G ratio of band intensity and red shift in G band from 1606 cm-1 to 1594 cm-1 in GO-CdHgTe QDs (2.6 nm) composites, which indicates structural modification of GO network. Steady state and time resolved photoluminescence (PL) spectroscopy shows the electronic interactions between photoexcited near infrared emitting CdHgTe QDs and GO. Another interesting observation is PL quenching in the presence of GO, and it is quite effective in the case of smaller size QDs (2.6 nm) compared to the larger size QDs (4.2 nm). Thus, the observed PL quenching is attributed to the photogenerated electron transfer from QDs to GO. The photoexcited electron transfer rate decreases from 2.2 × 109 to 1.5 × 108 s-1 with increasing particle size from 2.6 to 4.2 nm. Photoconductivity measurements on QDs-GO composite devices show nearly 3 fold increase in the current density under photo-illumination, which is a promising aspect for solar energy conversion and other optoelectronic applications.

  3. Growth, properties and applications of HgCdTe

    Science.gov (United States)

    Schmit, J. L.

    1983-12-01

    This paper provides primarily a review of the methods used to grow HgCdTe with a summary of some of its basic properties and applications. Methods of crystal growth fall generally into three classes: growth from the melt, from solution and from the vapor phase. All three methods have been and are being used to grow HgCdTe. The high vapor pressure of HgCdTe at the melting point, combined with a large segregation coefficient, have effectively limited the use of Czochralski or zone melting techniques, but two melt growth techniques have survived: (1) a variation of Bridgman growth called quench-anneal wherein a dendritic crystal is formed by quenching the melt and is homogenized by solid state recrystallization below the melting point, (2) a variation of freezing from a large volume called slush-growth wherein a melt is held in a temperature gradient for several weeks while a crystal grows. Growth from solution has taken the form of liquid phase epitaxy (LPE) on CdTe with the LPE systems including growth from Hg-rich, HgTe-rich and Te-rich solutions and using tipping, vertical dipping, vertical sliding and horizontal sliding. Vapor phase growth is very promising but is not yet in production. Techniques include growth by isothermal close spaced epitaxy in which HgTe is transported isothermally by chemical potential onto CdTe, molecular beam epitaxy (MBE) in which elements are evaporated in a high vacuum, and metal organic chemical vapor deposition (MOCVD) in which some of the metal atoms are carried to the substrate bound to organic radicals before being freed by pyrolysis. In all these methods, control of Hg pressure is a major concern. The fundamental properties discussed briefly are those of prime interest to detector manufacturers: energy gap ( Eg), intrinsic carrier concentration ( ni), and electrical activity of dopants. A reasonable fit to the Eg data from ˜ 20 papers is given by Eg = -0.302+1.93x+5.35×10 -4T(1-2x)-0.810x 2+0.832x 3. This gap, combined with k

  4. Selective separation of Hg(II) and Cd(II) from aqueous solutions by complexation-ultrafiltration process.

    Science.gov (United States)

    Zeng, Jian Xian; Ye, Hong Qi; Huang, Nian Dong; Liu, Jun Feng; Zheng, Li Feng

    2009-07-01

    Complexation-ultrafiltration process was investigated to separate selectively Hg(II) and Cd(II) from binary metal solutions by using poly (acrylic acid) sodium salt as a complexing agent. Effects of operating parameters on selective separation factors (beta(Cd/Hg)) of the both metals have been examined in detail. Results indicated that loading rate, pH, concentration of salt added and low-molecular competitive complexing agent affect significantly beta(Cd/Hg) value. Further, a concentration experiment was carried out according to the previous optimum parameters. Rejection coefficient of mercury is close to 1, while that of cadmium is about 0.1. The experiment was characterized by good effectiveness, and enabled the rapid linear increase of mercury concentration and very slow increase of cadmium concentration in the retentate. Then, a diafiltration technique was applied to separate further the both metals. Cadmium concentration in the retentate declines sharply with the diafiltration volume, whereas for mercury it is the contrary.

  5. Barrier formation at graded HgTe/CdTe heterojunctions

    Science.gov (United States)

    Goren, D.; Asa, G.; Nemirovsky, Y.

    1996-11-01

    Numerical calculations of graded HgTe/CdTe heterojunction (HJ) band diagrams at equilibrium are presented and discussed. The calculations are performed in the entire compositional range (0HJs are examined as a function of the graded region width and the graded region doping profiles. The graded region width and doping profiles were found to be the two main factors that determine whether barriers are formed as well as their shape and magnitude. The calculated results indicate that epitaxial ohmic HgTe contacts to extrinsic CdTe are possible, provided that the graded region is wider than one micron, and that it has the same doping type as the doping of the substrate with equal or higher absolute value. Further numerical calculations take into consideration the possible existence of distributed interface charges in the graded region of the HJ. It is shown that by assuming a classical transport over the potential barrier, the effective graded interface charge can be determined from the zero bias differential resistance of the HJ. Experimental transport measurements of metalorganic chemical vapor deposition (MOCVD) grown HgTe/p-CdTe graded HJs show a varying degree of rectification, indicating variations in the graded interface charge distributions which result from different MOCVD growth conditions.

  6. Fractionation distribution and preliminary ecological risk assessment of As, Hg and Cd in ornithogenic sediments from the Ross Sea region, East Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Chuangneng [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Liu, Xiaodong, E-mail: ycx@ustc.edu.cn [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Nie, Yaguang [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Emslie, Steven D. [Department of Biology and Marine Biology, University of North Carolina Wilmington, 601S. College Road, Wilmington, NC 28403 (United States)

    2015-12-15

    To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. Organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation. - Highlights: • Residual As holds a dominant position in ornithogenic sediments. • Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions. • Exchangeable Cd occupies a considerable proportion in ornithogenic sediments. • TOC is the main factor controlling the mobility of Hg and Cd in studied sediments.

  7. RF magnetron sputtering deposition of CdTe passivation on HgCdTe

    Science.gov (United States)

    Rutkowski, Jaroslaw; Adamiec, Krzysztof; Rogalski, Antoni

    1998-04-01

    In this study, we report the RF magnetron sputtering growth and characterization of CdTe passivant on bulk n-type HgCdTe. Our investigations include the HgCdTe surface preparation and in-situ pretreatment, deposition-induced surface damage, interface charge, CdTe film stoichiometry, and thermal stability. The metal-insulator-semiconductor test structures are processed and their electrical properties are measured by capacitance-voltage characteristics. The heterostructures are also characterized by reflectance measurement. In order to investigate the passivation properties of CdTe/HgCdTe heterostructures, we have modeled the band diagram of abrupt CdTe/HgCdTe heterojunction. The effect of sputtering growth condition parameters is also reported. The sputtering CdTe layers, exhibit excellent dielectric, insulating and mechano- chemical properties, as well as interface properties. The interfaces are characterized by slight accumulation and a small hysteresis. A carefully controlled growth process and surface pretreatment tailored to the specific material are required in order to obtain near flat band conditions on n- type materials. Additional informations on surface limitations are obtained from analyzing the I-V characteristics of photodiodes with metal gates covering the p-n junction surface location.

  8. Phase diagrams and microscopic structures of (Hg,Cd)Te, (Hg,Zn)Te, and (Cd,Zn)Te alloys

    Science.gov (United States)

    Patrick, R. S.; Chen, A.-B.; Sher, A.; Berding, M. A.

    1988-01-01

    A cluster theory based on the quasi-chemical approximation has been applied to study the local correlation bond-length distribution, and phase diagrams of the II-VI pseudobinary alloys Hg(1 - x)Cd(x)Te, Hg(1 - x)Zn(x)Te, and Cd(1 - x)Zn(x)Te. The cluster energy is calculated by letting it relax in some effective alloy medium and then considering the contributions from the strain and chemical energies. Two different models are presented to simulate the alloy medium. While both models show that all three alloys have nearly random distributions, the signs of the local correlation prove to be sensitive to the alloy medium chosen for the energy calculation. Good agreement is found between experiment and the bond lengths and phase diagrams in both models.

  9. Characterization of HgCdTe and HgCdSe Materials for Third Generation Infrared Detectors

    Science.gov (United States)

    2011-12-01

    etched HgCdTe photodiode .................................. 13 1.6 (a) Hybrid IR FPA, (b) cross section of structure, (c) indium bumps on Si...to areas of approximately 30 cm2. At this size, the wafers used for growth are unable to accommodate more than two 1024 × 1024 FPAs.3 For more...clear advantages over the other substrates because of its low cost, large wafer size, and a thermal-expansion coefficient that perfectly matches

  10. CdTe介质膜与HgCdTe晶片间界面特性的研究%STUDY OF THE INTERFACE OF THE SPUTTERING CdTe DIELECTRIC FILM AND HgCdTe CRYSTAL

    Institute of Scientific and Technical Information of China (English)

    周咏东; 赵军; 李言谨; 方家熊

    2000-01-01

    利用Ar+束溅射沉积技术在HgCdTe表面低温生长了CdTe介质薄膜.分别用CdTe介质膜和HgCdTe自身阳极氧化膜对HgCdTe表面钝化.利用光电导衰退信号波形的拟合,得到了不同表面钝化的HgCdTe非平衡载流子表面复合速度.结果表明,CdTe/HgCdTe界面质量已超过自身阳极氧化膜/HgCdTe界面质量.

  11. COMPARISON OF CHARACTERIZATION TECHNIQUES IN P-ON-N HgCdTe LWIR PHOTODIODES TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper standard techniques for characterization of HgCdTe liquid phase epitaxial layers (LPE) were presented. The performance of long wavelength p-on-n HgCdTe photodiodes fabricated by arsenic diffusion was described. The correlation between LPE HgCdTe material parameters and properties of the infrared photodiodes was demonstrated.

  12. Sequencing Batch Reactor (SBR) for the removal of Hg{sup 2+} and Cd{sup 2+} from synthetic petrochemical factory wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Malakahmad, Amirhossein, E-mail: amirhossein@petronas.com.my [Faculty of Energy and Environmental Studies, Islamic Azad University, Science and Research branch, Hesarak, Tehran (Iran, Islamic Republic of); Civil Engineering Department, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Hasani, Amirhesam [Faculty of Energy and Environmental Studies, Islamic Azad University, Science and Research branch, Hesarak, Tehran (Iran, Islamic Republic of); Eisakhani, Mahdieh [School of Social, Development and the Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia); Isa, Mohamed Hasnain [Civil Engineering Department, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia)

    2011-07-15

    Highlights: {yields} We assessed SBR performances to treat synthetic wastewater containing Hg{sup 2+} and Cd{sup 2+}. {yields} SBR was able to remove 76-90% of Hg{sup 2+} and 96-98% of Cd{sup 2+}. {yields} COD removal efficiency and MLVSS was affected by Hg{sup 2+} and Cd{sup 2+} concentrations. {yields} Removal was not only biological process but also by biosorption process of sludge. - Abstract: Petrochemical factories which manufacture vinyl chloride monomer and poly vinyl chloride (PVC) are among the largest industries which produce wastewater contains mercury and cadmium. The objective of this research is to evaluate the performance of a lab-scale Sequencing Batch Reactor (SBR) to treat a synthetic petrochemical wastewater containing mercury and cadmium. After acclimatization of the system which lasted 60 days, the SBR was introduced to mercury and cadmium in low concentrations which then was increased gradually to 9.03 {+-} 0.02 mg/L Hg and 15.52 {+-} 0.02 mg/L Cd until day 110. The SBR performance was assessed by measuring Chemical Oxygen Demand, Total and Volatile Suspended Solids as well as Sludge Volume Index. At maximum concentrations of the heavy metals, the SBR was able to remove 76-90% of Hg{sup 2+} and 96-98% of Cd{sup 2+}. The COD removal efficiency and MLVSS (microorganism population) in the SBR was affected by mercury and cadmium concentrations in influent. Different species of microorganisms such as Rhodospirilium-like bacteria, Gomphonema-like algae, and sulfate reducing-like bacteria were identified in the system. While COD removal efficiency and MLVSS concentration declined during addition of heavy metals, the appreciable performance of SBR in removal of Hg{sup 2+} and Cd{sup 2+} implies that the removal in SBR was not only a biological process, but also by the biosorption process of the sludge.

  13. Transient charge technique investigation of HgI/sub 2/ and CdSe nuclear detectors

    Energy Technology Data Exchange (ETDEWEB)

    Roth, M.; Burger, A.; Nissenbaum, J.; Schieber, M.

    1987-02-01

    The use of the Transient Charge Technique (TCT) for the evaluation of high resistivity Mercuric Iodide and Cadmium Selenide nuclear radiation detectors is suggested. It has been shown that the real values of mobilities and trapping times of electrons and holes in HgI/sub 2/ can be easily obtained from the analysis of the voltage transient response to drift of charge carriers created by alpha particles. This allows one to evaluate the bulk transport properties of the material and, additionally, to estimate accurately the surface recombination velocity of the carriers. Preliminary results on the shape of voltage transients in CdSe are also reported, and the limitations of the use of the TCT for characterization of both materials are discussed.

  14. Cd/Hg cationic substitution in magic-sized CdSe clusters: Optical characterization and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Antanovich, Artsiom; Prudnikau, Anatol; Gurin, Valerij; Artemyev, Mikhail, E-mail: m_artemyev@yahoo.com

    2015-07-09

    Highlights: • HgSe magic-sized clusters were prepared via Cd/Hg cationic exchange in pyridine. • Upon cationic exchange CdSe clusters behave differently from quantum dots or rods. • Theoretical calculations of magic-sized clusters agree well with experimental data. - Abstract: We examine conversion of magic-sized CdSe clusters (MSCs) into HgSe ones by means of Cd/Hg cation exchange. With this procedure Cd{sub 8}Cd{sub 17}– and Cd{sub 32}–selenide clusters can be converted into corresponding Hg{sub 8}–, Hg{sub 17}– and Hg{sub 32}–selenide ones. Upon cationic exchange MSCs behavior differs from that of bulkier counterparts – larger (2–3 nm) quantum dots. Unlike CdSe colloidal quantum dots, magic-sized clusters are converted in fast and complete manner without a formation of intermediate mixed Cd{sub x}Hg{sub 1−x} compounds that was established on the basis of optical absorption spectroscopy and chemical composition analysis. These assumptions were supported by DFT quantum chemical calculations performed for Cd{sub 8}–, Cd{sub 17}– and Hg{sub 8}–, Hg{sub 17}–selenide model clusters. Energies of experimental and calculated optical transitions were compared in order to prove the isostructural character of cationic substitution in magic-sized clusters.

  15. Simulation of Small-Pitch HgCdTe Photodetectors

    Science.gov (United States)

    Vallone, Marco; Goano, Michele; Bertazzi, Francesco; Ghione, Giovanni; Schirmacher, Wilhelm; Hanna, Stefan; Figgemeier, Heinrich

    2017-09-01

    Recent studies indicate as an important technological step the development of infrared HgCdTe-based focal plane arrays (FPAs) with sub-wavelength pixel pitch, with the advantage of smaller volume, lower weight, and potentially lower cost. In order to assess the limits of pixel pitch scaling, we present combined three-dimensional optical and electrical simulations of long-wavelength infrared HgCdTe FPAs, with 3 μm, 5 μm, and 10 μm pitch. Numerical simulations predict significant cavity effects, brought by the array periodicity. The optical and electrical contributions to spectral inter-pixel crosstalk are investigated as functions of pixel pitch, by illuminating the FPAs with Gaussian beams focused on the central pixel. Despite the FPAs being planar with 100% pixel duty cycle, our calculations suggest that the total crosstalk with nearest-neighbor pixels could be kept acceptably small also with pixels only 3 μ m wide and a diffraction-limited optical system.

  16. Real-time control of HgCdTe growth by organometallic vapor phase epitaxy using spectroscopic ellipsometry

    Science.gov (United States)

    Murthy, Srikanteswara Dakshina; Bhat, Ishwara; Johs, Blaine; Pittal, Shakil; He, Ping

    1995-09-01

    The use of spectroscopic ellipsometry for monitoring the vapor phase epitaxial growth of mercury cadmium telluride (Hg1-xCdxTe) in real-time is demonstrated. The ellipsometer is used to perform system identification of the chemical vapor deposition reactor used for the growth of CdTe and to measure the response of the reactor to different growth conditions. The dynamic behavior of the reactor is also studied by evaluating the gas transport delay. The optical constants of Hg1-xCdxTe are determined at the growth temperature for different compositions. In-situ real-time composition control is performed during the growth of Hg1-xCdxTe. The required target compositions are attained by the ellipsometer and appropriate corrections are also made by the controller when a noise input in the form of a temperature variation is introduced.

  17. Assessment of cadmium (Cd) concentration in arable soil in China.

    Science.gov (United States)

    Zhang, Xiuying; Chen, Dongmei; Zhong, Taiyang; Zhang, Xiaomin; Cheng, Min; Li, Xinhui

    2015-04-01

    Cadmium (Cd) concentration in arable soil has drawn broad public attention due to its direct effect on Cd concentration in food. However, there have been few studies of surveying Cd accumulation on the national scale in China. This paper collected 486 studies of Cd concentrations in Chinese arable soil. The results showed that the average Cd concentration was 0.27 mg/kg, higher than its background value, indicating that Cd had been introduced into arable soil by human activity. The Cd concentrations in areas of mining and smelting, urban areas, and areas irrigated by wastewater were obviously higher than that in remote areas. Spatially, Cd concentrations were lower in the north than those in the south, and many hotspots existed throughout China due to mining and smelting activities. Most Cd in the arable soil were accumulated from external sources in all investigated provinces except Ningxia Hui Autonomous Region.

  18. MBE Growth and Characterization of Hg Based Compounds and Heterostructures

    Science.gov (United States)

    2002-06-03

    The molecular beam epitaxy ( MBE ) growth of Mercury Cadmium Telluride (Hg(1-x)Cd(x)Te) alloys and type III HgTe/Hg(1-x)Cd(x)Te heterostructures has...been discussed, including similarities and differences between the (0 0 1) and (1 1 2)Beta orientations. Furthermore, the MBE growth of HgTe-based

  19. Minority carrier lifetimes in different doped LWIR HgCdTe grown by LPE

    Science.gov (United States)

    Qiu, GuangYin; Wei, YanFeng; Sun, QuanZhi; Yang, JianRong

    2012-10-01

    The carrier lifetimes of different types of p-type doped HgCdTe(x~0.23) long wavelength infrared (LWIR) epilayers were measured which were Hg-vacancy, Au and arsenic doped ones prepared by Te-rich Liquid-phase epitaxy (LPE). By comparing the lifetimes of Hg-vacancy and extrinsic doped HgCdTe, we focus on three primary mechanisms limiting the lifetimes in these different p-type HgCdTe samples: radiative recombination, Auger recombination and Schokley-Read- Hall (SRH) Recombination. The recombination mechanism in p-type HgCdTe is the SRH recombination at low temperatures and Auger and radiative recombination at high temperature. It is found that the lifetime of As-doped and Au-doped HgCdTe is far longer than that of Hg-vacancy-doped sample which is caused by the deep energy level of the Hg-vacancy acceptor that is considered as a recombination center in HgCdTe. Also we found lifetime in those p-type doped HgCdTe LWIR epilayers is limited by SRH by comparing the experimental lifetimes with the calculated data. Impurity doping was found to have a main effect on minority carrier lifetime.

  20. Tinjauan terhadap tailing mengandung unsur pencemar Arsen (As), Merkuri (Hg), Timbal (Pb), dan Kadmium (Cd) dari sisa pengolahan bijih logam

    OpenAIRE

    Danny Zulkifli Herman

    2014-01-01

    http://dx.doi.org/10.17014/ijog.vol1no1.20064aWhen tailing of a mining activity is discharged into either landscape or river body, the pollutan element wastes are possible to disperse within those areas and may cause pollution on environment. The environment pollution hazards of arsenic (As), mercury (Hg), lead (Pb) and cadmium (Cd) probably occurred if tailing with the content of those elements is not handled properly. Particularly in the tropical regions, higher rates of chemical weathering...

  1. Heavy metals (Pb, Cd, As and MeHg) as risk factors for cognitive dysfunction: A general review of metal mixture mechanism in brain.

    Science.gov (United States)

    Karri, Venkatanaidu; Schuhmacher, Marta; Kumar, Vikas

    2016-12-01

    Human exposure to toxic heavy metals is a global challenge. Concurrent exposure of heavy metals, such as lead (Pb), cadmium (Cd), arsenic (As) and methylmercury (MeHg) are particularly important due to their long lasting effects on the brain. The exact toxicological mechanisms invoked by exposure to mixtures of the metals Pb, Cd, As and MeHg are still unclear, however they share many common pathways for causing cognitive dysfunction. The combination of metals may produce additive/synergetic effects due to their common binding affinity with NMDA receptor (Pb, As, MeHg), Na(+) - K(+) ATP-ase pump (Cd, MeHg), biological Ca(+2) (Pb, Cd, MeHg), Glu neurotransmitter (Pb, MeHg), which can lead to imbalance between the pro-oxidant elements (ROS) and the antioxidants (reducing elements). In this process, ROS dominates the antioxidants factors such as GPx, GS, GSH, MT-III, Catalase, SOD, BDNF, and CERB, and finally leads to cognitive dysfunction. The present review illustrates an account of the current knowledge about the individual metal induced cognitive dysfunction mechanisms and analyse common Mode of Actions (MOAs) of quaternary metal mixture (Pb, Cd, As, MeHg). This review aims to help advancement in mixture toxicology and development of next generation predictive model (such as PBPK/PD) combining both kinetic and dynamic interactions of metals. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. HgCdTe detector technology at Kunming Institute of Physics

    Science.gov (United States)

    Su, Junhong; Zeng, Gehong

    1996-09-01

    HgCdTe detector and thermal image system laboratories at Kunming Institute of Physics have been carrying the research and development of HgCdTe detectors and thermal imaging systems for a wide range applications for over 20 years. During this period, significant progress has been made in many areas such as HgCdTe material, detector, miniature dewar and cooler to meet the requirements of civil and military operations. This paper describes these activities and present status of HgCdTe technology at Kunming Institute of Physics, and some of the problems we faced and how they were solved.

  3. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

    Science.gov (United States)

    Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

    2011-06-15

    A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively.

  4. Nondestructive Characterization of Residual Threading Dislocation Density in HgCdTe Layers Grown on CdZnTe by Liquid-Phase Epitaxy

    Science.gov (United States)

    Fourreau, Y.; Pantzas, K.; Patriarche, G.; Destefanis, V.

    2016-09-01

    The performance of mercury cadmium telluride (MCT)-based infrared (IR) focal-plane arrays is closely related to the crystalline perfection of the HgCdTe thin film. In this work, Te-rich, (111)B-oriented HgCdTe epilayers grown by liquid-phase epitaxy on CdZnTe substrates have been studied. Surface atomic steps are shown on as-grown MCT materials using atomic force microscopy (AFM) and white-light interferometry (WLI), suggesting step-flow growth. Locally, quasiperfect surface spirals are also evidenced. A demonstration is given that these spirals are related to the emergence of almost pure screw threading dislocations. A nondestructive and quantitative technique to measure the threading dislocation density is proposed. The technique consists of counting the surface spirals on the as-grown MCT surface from images obtained by either AFM or WLI measurements. The benefits and drawbacks of both destructive—chemical etching of HgCdTe dislocations—and nondestructive surface imaging techniques are compared. The nature of defects is also discussed. Finally, state-of-the-art threading dislocation densities in the low 104 cm-2 range are evidenced by both etch pit density (EPD) and surface imaging measurements.

  5. Can graphene make better HgCdTe infrared detectors?

    Directory of Open Access Journals (Sweden)

    Shi Yanli

    2011-01-01

    Full Text Available Abstract We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT thin wafers at room temperature. The proposed technique does not cause any thermal and mechanical damages to the MCT wafers. It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K. Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K. These experimental findings suggest that, from a physics point of view, graphene can be utilized as transparent electrodes as a replacement for metal electrodes while producing better and cheaper MCT infrared detectors.

  6. ROIC for HgCdTe e-APD FPA

    Science.gov (United States)

    Chen, Guoqiang; Zhang, Junling; Wang, Pan; Zhou, Jie; Gao, Lei; Ding, Ruijun

    2013-08-01

    Ultra-low light imaging and passive/active dual mode imaging require very low noise optical receivers to achieve detection of fast and weak optical signal. HgCdTe electrons initiated avalanche photodiodes (e-APDs) in linear multiplication mode is the detector of choice thanks to its high quantum efficiency, high gain at low bias, high bandwidth and low noise factor. In my work, a passive/active dual mode readout integrated circuit (ROIC) of e-APD focal plane array (FPA) is designed. Unit cell circuit architecture of ROIC includes a capacitance feedback transimpedance amplifier (CTIA) as preamplifier of ROIC, a high voltage protection module, a comparator, a Sample-Hold circuit module, and output driver stage. There is a protection module in every unit cell circuit which can avoid ROIC to be damaged from avalanche breakdown of some diodes of detector. Conventional 5V CMOS process is applied to implement the high voltage protection with the small area rather than Laterally Diffused Metal Oxide Semiconductor (LDMOS) in high voltage BCD process in the limited 100um×100um pitch area. In CTIA module, three integration capacitances are included in the CTIA module, two of them are switchable to provide different well capacity and noise. Constraints such as pixel area, stability and power lead us design toward a simple one-stage cascade operational transconductance amplifier (OTA) as pre-amplifier. High voltage protection module can protect ROIC to be damaged because of breakdown of some avalanche diodes.

  7. Spectroscopic and electrochemical monitoring of band structure changes during the alloying of CdTe QDs by Hg2+ ions

    Science.gov (United States)

    Tynkevych, Olena O.; Ranoszek-Soliwoda, Katarzyna; Grobelny, Jaroslaw; Selyshchev, Oleksandr V.; Khalavka, Yuriy B.

    2016-10-01

    The series of ultrasmall thioglycolic acid-stabilized colloidal Cd1-x Hg x Te QDs (with d ≈ 2.3 nm) with different % Hg2+ content were synthesized by an ion-exchange reaction in water solution. The resulting Cd1-x Hg x Te QDs were characterized using UV-vis absorption and photoluminescent optical spectroscopic studies, cyclic voltammetry and scanning transmission electron microscopy. By comparison of the results from different methods we conclude that Hg-alloying occurs in three stages—with the formation of three different types of QDs structures, namely core/shell CdTe/Cd1-x Hg x Te QDs, core/shell/shell CdTe/Cd1-x Hg x Te/CdHg QDs and core/shell Cd1-x Hg x Te/CdHg QDs.

  8. Progress in MOCVD growth of HgCdTe epilayers for HOT infrared detectors

    Science.gov (United States)

    Kebłowski, A.; Gawron, W.; Martyniuk, P.; Stepień, D.; Kolwas, K.; Piotrowski, J.; Madejczyk, P.; Kopytko, M.; Piotrowski, A.; Rogalski, A.

    2016-05-01

    In this paper we present progress in MOCVD growth of (100) HgCdTe epilayers achieved recently at the Institute of Applied Physics, Military University of Technology and Vigo System S.A. It is shown that MOCVD technology is an excellent tool in fabrication of different HgCdTe detector structures with a wide range of composition, donor/acceptor doping and without post grown annealing. Particular progress has been achieved in the growth of (100) HgCdTe epilayers for long wavelength infrared photoconductors operated in HOT conditions. The (100) HgCdTe photoconductor optimized for 13-μm attain detectivity equal to 6.5x109 Jones and therefore outperform its (111) counterpart. The paper also presents technological progress in fabrication of MOCVD-grown (111) HgCdTe barrier detectors. The barrier device performance is comparable with state-of-the-art of HgCdTe photodiodes. The detectivity of HgCdTe detectors is close to the value marked HgCdTe photodiodes. Dark current densities are close to the values given by "Rule 07".

  9. MBE Growth and Transfer of HgCdTe Epitaxial Films from InSb Substrates

    Science.gov (United States)

    de Lyon, T. J.; Rajavel, R. D.; Nosho, B. Z.; Terterian, S.; Beliciu, M. L.; Patterson, P. R.; Chang, D. T.; Boag-O'Brien, M. F.; Holden, B. T.; Jacobs, R. N.; Benson, J. D.

    2010-07-01

    An investigation of the heteroepitaxial growth of HgCdTe films onto InSb(211)B substrates is reported. High-quality HgCdTe(211)B single-crystal films have been successfully deposited onto InSb(211)B substrates and have been characterized with x-ray diffraction rocking curve analysis, etch pit density analysis, and surface void defect mapping. X-ray rocking curve (422) reflection full-width at half-maximum of 60 arcsec has been obtained for 7- μm-thick x = 0.22 HgCdTe epitaxial films, and etch pit densities of 3 × 106 cm-2 to 3 × 107 cm-2 have been observed. A significant reduction in HgCdTe void defect densities to 100 cm-2 to 200 cm-2 has been observed on InSb, including a complete absence of large “void cluster” defects that are often observed for growth on CdZnTe. Wafer bow induced by the growth of HgCdTe on InSb is less than 1 μm for 2-inch-diameter substrates. Significant diffusion of In into HgCdTe is observed for HgCdTe/InSb wafers that are subjected to Hg anneals at 250°C to 300°C. A preliminary investigation of the transfer of HgCdTe films from InSb onto Si substrates has also been undertaken, using an adhesive wafer bonding approach evaluated with scanning acoustic microscopy. The infrared transmission characteristics of the bonding adhesive have been investigated with respect to postgrowth annealing procedures to establish the compatibility of the bonding approach with HgCdTe device processing and detector operation.

  10. The longitudinal translocation characters and the influencing factors of Hg, Cd in the soil

    Directory of Open Access Journals (Sweden)

    Zhang Yujuan

    2006-11-01

    Full Text Available Combining the methods of simulation test and field survey, the longitudinal distribution and the influencing factors of Hg and Cd in the profile in the typical sewage irrigation area were studied in this paper and the result shows: (1 the content distribution of Hg, Cd in the superficial soil profile was higher than that in the bottom and the content decreased with the increase of the depth, the translocation ability of the Hg, Cd in the garden mould and cinnamon soil were lower than that in the paddy soil and fluve-aquic soil, the longitudinal translocation ability of the Cd in the soil profile was stronger than that of Hg; (2 Hg was accumulated in the different soil and has the highest accumulation rate in the paddy soil and the lowest in the cinnamon soil; the translocation order of the Cd in the different was: garden mould > paddy soil > cinnamon soil > fluve-aquic soil; (3 the concentration of Hg, Cd in the soil leacheate increased with the concentration increase of Hg, Cd in the sewage, the migration rate increased with the roughness of the soil quality and decreased with the increase of pH and soil organic matter.

  11. Effect of magnetic field on energy spectrum and localization of electron in CdS/HgS/CdS/HgS/CdS multilayered spherical nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Holovatsky, V.A., E-mail: ktf@chnu.edu.ua; Bernik, I.B.; Yakhnevych, M. Ya.

    2017-03-01

    The theoretical investigation of magnetic field effect on energy spectrum and localization of the electron and oscillator strengths of intraband quantum transitions in the nanostructure CdS/HgS/CdS/HgS/CdS is performed. The calculations are made in the framework of effective mass approximation and rectangular potential barriers model using the method of the expansion of quasi-particle wave functions over the complete basis of functions obtained as the exact solutions of the Schrodinger equation for the electron in the nanostructure without the magnetic field. It is shown that the magnetic field violates the spherical symmetry of the system and takes off the degeneration of energy spectrum with respect to the magnetic quantum number. The energy of the electron in the states with m≥0 increases when magnetic field enhances; for the states with m<0 these dependences are non-monotonous (decreasing at first and then increasing). Moreover, the ground state of electron is formed alternately by the states with m=0, −1, −2, …. Magnetic field influences on the distribution of quasi-particle density. It is shown that the electron significantly changes its localization in the nanostructure with two potential wells tunneling through the potential barrier under the effect of magnetic field, changing the oscillator strengths of intraband quantum transitions.

  12. Effect of magnetic field on energy spectrum and localization of electron in CdS/HgS/CdS/HgS/CdS multilayered spherical nanostructure

    Science.gov (United States)

    Holovatsky, V. A.; Bernik, I. B.; Yakhnevych, M. Ya.

    2017-03-01

    The theoretical investigation of magnetic field effect on energy spectrum and localization of the electron and oscillator strengths of intraband quantum transitions in the nanostructure CdS/HgS/CdS/HgS/CdS is performed. The calculations are made in the framework of effective mass approximation and rectangular potential barriers model using the method of the expansion of quasi-particle wave functions over the complete basis of functions obtained as the exact solutions of the Schrodinger equation for the electron in the nanostructure without the magnetic field. It is shown that the magnetic field violates the spherical symmetry of the system and takes off the degeneration of energy spectrum with respect to the magnetic quantum number. The energy of the electron in the states with m≥0 increases when magnetic field enhances; for the states with m<0 these dependences are non-monotonous (decreasing at first and then increasing). Moreover, the ground state of electron is formed alternately by the states with m=0, -1, -2, …. Magnetic field influences on the distribution of quasi-particle density. It is shown that the electron significantly changes its localization in the nanostructure with two potential wells tunneling through the potential barrier under the effect of magnetic field, changing the oscillator strengths of intraband quantum transitions.

  13. In situ compositional control of advanced HgCdTe-based IR detectors

    Science.gov (United States)

    Almeida, L. A.; Dinan, J. H.

    1999-05-01

    The application of a feedback control system for maintaining a desired compositional profile during Hg 1- xCd xTe epitaxy is reported. A spectroscopic ellipsometer monitored the optical properties of Hg 1- xCd xTe films during deposition by molecular beam epitaxy. A library of optical constants was established from in situ measurements of multiple layers of varying composition. The compositions were subsequently determined ex situ using Fourier transform infrared spectroscopy. This work represents an extension of the compositional range of this control system to measure the x-values of Hg 1- xCd xTe sensitive to long-, mid-, and short-wavelength infrared (LWIR, MWIR, and SWIR) radiation (0.16CdTe effusion cell. The application of this control system is demonstrated by measuring the compositional profile of a three layer Hg 1- xCd xTe structure suitable for use as an MWIR/SWIR detector.

  14. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  15. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  16. Cadmium telluride (CdTe) and cadmium selenide (CdSe) leaching behavior and surface chemistry in response to pH and O2.

    Science.gov (United States)

    Zeng, Chao; Ramos-Ruiz, Adriana; Field, Jim A; Sierra-Alvarez, Reyes

    2015-05-01

    Cadmium telluride (CdTe) and cadmium selenide (CdSe) are increasingly being applied in photovoltaic solar cells and electronic components. A major concern is the public health and ecological risks associated with the potential release of toxic cadmium, tellurium, and/or selenium species. In this study, different tests were applied to investigate the leaching behavior of CdTe and CdSe in solutions simulating landfill leachate. CdTe showed a comparatively high leaching potential. In the Toxicity Characteristic Leaching Procedure (TCLP) and Waste Extraction Test (WET), the concentrations of cadmium released from CdTe were about 1500 and 260 times higher than the regulatory limit (1 mg/L). In contrast, CdSe was relatively stable and dissolved selenium in both leaching tests was below the regulatory limit (1 mg/L). Nonetheless, the regulatory limit for cadmium was exceeded by 5- to 6- fold in both tests. Experiments performed under different pH and redox conditions confirmed a marked enhancement in CdTe and CdSe dissolution both at acidic pH and under aerobic conditions. These findings are in agreement with thermodynamic predictions. Taken as a whole, the results indicate that recycling of decommissioned CdTe-containing devices is desirable to prevent the potential environmental release of toxic cadmium and tellurium in municipal landfills.

  17. Recent progress in MBE grown HgCdTe materials and devices at UWA

    Science.gov (United States)

    Gu, R.; Lei, W.; Antoszewski, J.; Madni, I.; Umana-Menbreno, G.; Faraone, L.

    2016-05-01

    HgCdTe has dominated the high performance end of the IR detector market for decades. At present, the fabrication costs of HgCdTe based advanced infrared devices is relatively high, due to the low yield associated with lattice matched CdZnTe substrates and a complicated cooling system. One approach to ease this problem is to use a cost effective alternative substrate, such as Si or GaAs. Recently, GaSb has emerged as a new alternative with better lattice matching. In addition, implementation of MBE-grown unipolar n-type/barrier/n-type detector structures in the HgCdTe material system has been recently proposed and studied intensively to enhance the detector operating temperature. The unipolar nBn photodetector structure can be used to substantially reduce dark current and noise without impeding photocurrent flow. In this paper, recent progress in MBE growth of HgCdTe infrared material at the University of Western Australia (UWA) is reported, including MBE growth of HgCdTe on GaSb alternative substrates and growth of HgCdTe nBn structures.

  18. The Study on the Properties of CdTe Buffer Layer for MBE HgCdTe Epilayer%分子束外延HgCdTe薄膜的CdTe缓冲层特性研究

    Institute of Scientific and Technical Information of China (English)

    宋立媛; 唐利斌; 李艳辉; 孔令德; 陈雪梅

    2009-01-01

    CdTe是GaAs衬底上分子束外延(MBE)HgCdTe薄膜时的缓冲层,引入缓冲层的目的是减小失配位错,CdTe缓冲层的生长直接影响到后续HgCdTe薄膜的制备质量,然而目前现有文献鲜有报道CdTe缓冲层的最佳厚度.采用X射线双晶衍射、位错腐蚀坑密度(EPD)、FT-IR和椭圆偏振光谱的方法,从CdTe缓冲层厚度对位错密度的影响入手,分析并确定了理想的CdTe缓冲层厚度.%CdTe is the buffer layer of GaAs substrate for HgCdTe eoilayer grown by MBE,The purpose for introduction of buffer laver is to decrease the mismatched dislocation,the growth of CdTe buffer layer directly affects the quality of foilowing grown HgCdTe thin film.However,up to now only few papers have reported the optimum thickness for CdTe buffer layer.By using of X-ray double ervstal diffraction,EPD,FT-IR as well as soectroscopic ellipsometry the paper has studied the effects of the thickness on EPD for CdTe buffer layer,the optimum thickness of CdTe buffer layer has been obtained.

  19. Ab Initio Investigation of the Structural and Electronic Properties of HgTe/CdTe Superlattices

    Science.gov (United States)

    Laref, A.; Alsagri, M.; Laref, S.; Luo, S. J.

    2017-08-01

    We carried out first-principle calculations to examine the impact of layer periodicity and strain on the structural and electronic features of HgTe/CdTe superlattices (SLs). The full-potential linearized augmented plane wave methodology is used to determine the electronic characteristics of these CdTe-HgTe heterojunctions. The CdTe and HgTe layers have a strong effect on the emerged fundamental energy gap of the SLs owing to the peculiar quantum confinement effect. The impact of layer thickness changes and strain are indispensable for engineering the energy band gap of HgTe/CdTe SLs. This could lead to an enormous development in the optoelectronic characteristics of these SLs, which may result in their broad applications in electronic devices.

  20. Characteristics of HgCdTe epilayer grown by LPE using horizontal slider

    Indian Academy of Sciences (India)

    J K Radhakrishnan; S Sitharaman; S C Gupta

    2002-11-01

    The characteristics of HgCdTe epilayers grown in a modified horizontal slider system, are reported here. The surface morphology of the grown layers, their IR transmission characteristics, depth and lateral compositional uniformity, structural and electrical characteristics are discussed.

  1. Low-Roughness Plasma Etching of HgCdTe Masked with Patterned Silicon Dioxide

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Yin, W. T.; Huang, J.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2011-08-01

    A novel mask technique utilizing patterned silicon dioxide films has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal-plane arrays (IRFPAs). High-density silicon dioxide films were deposited at temperature of 80°C, and a procedure for patterning and etching of HgCdTe was developed by standard photolithography and wet chemical etching. Scanning electron microscopy (SEM) showed that the surfaces of inductively coupled plasma (ICP) etched samples were quite clean and smooth. Root-mean-square (RMS) roughness characterized by atomic force microscopy (AFM) was less than 1.5 nm. The etching selectivity between a silicon dioxide film and HgCdTe in the samples masked with patterned silicon dioxide films was greater than 30:1. These results show that the new masking technique is readily available and promising for HgCdTe mesa etching.

  2. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Voxtel Inc. proposes to optimize the design of a large area, 1.55?m sensitive HgCdTe avalanche photodiode (APD) that achieves high gain with nearly no excess noise....

  3. Single Photon Sensitive HgCdTe Avalanche Photodiode Detector (APD) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A linear mode HgCdT electron-initiated avalanche photodiode (EAPD) capable of 1570nm photon detection efficiency (PDE) at >10 MHz will be developed. The Phase I...

  4. Engineering steps for optimizing high temperature LWIR HgCdTe photodiodes

    Science.gov (United States)

    Madejczyk, Pawel; Gawron, Waldemar; Martyniuk, Piotr; Keblowski, Artur; Pusz, Wioletta; Pawluczyk, Jaroslaw; Kopytko, Malgorzata; Rutkowski, Jaroslaw; Rogalski, Antoni; Piotrowski, Jozef

    2017-03-01

    The authors report on energy gap engineering solutions to improve the high-temperature performance of long-wave infrared (LWIR) HgCdTe photodiodes. Metalorganic chemical vapour deposition (MOCVD) technology with a wide range of composition and donor/acceptor doping and without ex-situ post grown annealing seems to be an excellent tool for HgCdTe heterostructure epitaxial growth. The heterojunction HgCdTe photovoltaic device based on epitaxial graded gap structures integrated with Auger-suppression is a magnificent solution for high operating temperature (HOT) infrared detectors. The thickness, composition and doping of HgCdTe heterostructure were optimized with respect to photoelectrical parameters like dark current, the responsivity and the response time. In this paper we focus on graded interface abruptness in the progressive optimization.

  5. Molecular beam epitaxy of CdTe and HgCdTe on large-area Si(100)

    Science.gov (United States)

    Sporken, R.; Lange, M. D.; Faurie, Jean-Pierre

    1991-09-01

    The current status of molecular beam epitaxy (MBE) of CdTe and HgCdTe on Si(100) is reviewed. CdTe and HgCdTe grow in the (111)B orientation on Si(100); monocrystalline films with two domains are obtained on most nominal Si(100) substrates, single domain films are grown on misoriented substrates and on nominal Si(100) preheated to 900-950 degree(s)C. Double-crystal x-ray rocking curves (DCRCs) with full-width at half-maximum (FWHM) as low as 110 arcsec are reported for HgCdTe on silicon; these layers are n-type, and electron mobilities higher than 5 X 104 cm2V-2s-1 are measured at 23 K for x equals 0.26. Excellent thickness and composition uniformity is obtained: standard deviation of the CdTe thickness 0.4% of the average thickness on 2-in. and 2.3% on 5-in., standard deviation of the Cd concentration in the HgCdTe layers 0.6% of the average concentration on 3-in. and 2.4% on 5-in. First results regarding growth of CdTe on patterned Si substrates are also reported.

  6. Cd, Pb and Hg Biomonitoring in Fish of the Mediterranean Region and Risk Estimations on Fish Consumption

    Directory of Open Access Journals (Sweden)

    Elisavet A. Renieri

    2014-08-01

    Full Text Available Cadmium (Cd, lead (Pb and mercury (Hg are toxic metals with increasing interest due to their tendency to bioaccumulate in fish tissue which may pose a threat to human health via fish consumption. This review of the recent literature on Cd, Pb, Hg levels summarizes data of fish biomonitoring studies in the Mediterranean Sea in order to determine potential risks due to dietary intake of metals. The analytical methods applied are described, with Atomic Absorption Spectroscopy and Inductively Coupled Plasma Mass Spectroscopy being the most popular. Most of the literature reviewed is focused on the Eastern Mediterranean. Results from the studies indicate that metals mostly accumulate in liver, followed by muscle. Although there are few studies reporting metal levels in fish exceeding the maximum residue levels (MRLs, the bulk of the studies cite levels below the MRLs. The hazard index (HI of fish consumption, namely the ratio of estimated weekly intake to provisional tolerable weekly intake (EWI/PTWI was estimated for adult consumers and no risk emerged. The EWI/PTWI ratios of lead and mercury for Italy (0.14 and 0.22 respectively represent the highest HI levels estimated. In view of maximizing the benefits while minimizing the risks of fish consumption, a more detailed fish-specific database on intakes for consumers is required and extended bimonitoring in as many regions as possible.

  7. Impulse coupling between laser and HgCdTe

    Science.gov (United States)

    Liu, Ji; Li, Xiangyang; Hu, Xierong; Fang, Jiaxiong; Xu, Guosen; Shen, Jie

    1994-10-01

    The interaction between Mercury Cadmium Telluride (MCT) and single pulse of Nd:YAG laser with 1.06 micrometers wavelength and 10 ns pulse duration was studied. The impulse delivered to MCT sample was measured by using ballistic pendulum method. The experiment shows that the momentum transfer results from material being ejected from MCT surface under the impinging of intense pulse laser. The impulse coupling coefficient of MCT gets to its maximum 14.3 dyne(DOT)s/J when incident laser power density is about 7.6 X 10(superscript 8) W/cm(superscript 2). By using 1D model of gas-dynamics, the impulse coupling coefficients have been calculated. The calculated results agree well with measured ones in the region of incident power density larger than 1.5 X 10(superscript 9) W/cm(superscript 2).

  8. Tinjauan terhadap tailing mengandung unsur pencemar Arsen (As, Merkuri (Hg, Timbal (Pb, dan Kadmium (Cd dari sisa pengolahan bijih logam

    Directory of Open Access Journals (Sweden)

    Danny Zulkifli Herman

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol1no1.20064aWhen tailing of a mining activity is discharged into either landscape or river body, the pollutan element wastes are possible to disperse within those areas and may cause pollution on environment. The environment pollution hazards of arsenic (As, mercury (Hg, lead (Pb and cadmium (Cd probably occurred if tailing with the content of those elements is not handled properly. Particularly in the tropical regions, higher rates of chemical weathering and bio-chemical activity will contribute a rapid mobilization of the most potentially toxic elements.One of adverse health effects from arsenic to human life is in the case of arsenic-contained drinking waters exceed the threshold limit value. As a result, it will create chronic symptoms of toxicity within the human body such as gastro-intestinal irritation, nerve damage and tissue wastage. Tailing originated from amalgamation processing of gold ore enables its mercury waste to disperse in the vicinity of mining area and may form environment pollution by either organic or inorganic mercury. The pollution would be more hazardous to human health if mercury element in the water body transform biochemically into a compound of methylmercury. There is a variety of mechanisms by micro-organism which can bring about the formation of the very toxic methylmercury species, particularly with regard to its uptake by fish. Effects to the human health from the organic mercury include the blood-brain barrier and upsetting the metabolism of the nervous system. Whilst the main toxic effect of inorganic mercury is disruption the functions of kidneys and liver within human body. Most mining activity of base metal may discharge tailing with a significant lead (Pb content. Lead is a cumulative poison, hence absorbing this element by human body with particularly exceeding its threshold limit value will bind strongly to a large number of molecules such as amino acids, haemoglobin

  9. Tinjauan terhadap tailing mengandung unsur pencemar Arsen (As, Merkuri (Hg, Timbal (Pb, dan Kadmium (Cd dari sisa pengolahan bijih logam

    Directory of Open Access Journals (Sweden)

    Danny Zulkifli Herman

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol1no1.20064aWhen tailing of a mining activity is discharged into either landscape or river body, the pollutan element wastes are possible to disperse within those areas and may cause pollution on environment. The environment pollution hazards of arsenic (As, mercury (Hg, lead (Pb and cadmium (Cd probably occurred if tailing with the content of those elements is not handled properly. Particularly in the tropical regions, higher rates of chemical weathering and bio-chemical activity will contribute a rapid mobilization of the most potentially toxic elements.One of adverse health effects from arsenic to human life is in the case of arsenic-contained drinking waters exceed the threshold limit value. As a result, it will create chronic symptoms of toxicity within the human body such as gastro-intestinal irritation, nerve damage and tissue wastage. Tailing originated from amalgamation processing of gold ore enables its mercury waste to disperse in the vicinity of mining area and may form environment pollution by either organic or inorganic mercury. The pollution would be more hazardous to human health if mercury element in the water body transform biochemically into a compound of methylmercury. There is a variety of mechanisms by micro-organism which can bring about the formation of the very toxic methylmercury species, particularly with regard to its uptake by fish. Effects to the human health from the organic mercury include the blood-brain barrier and upsetting the metabolism of the nervous system. Whilst the main toxic effect of inorganic mercury is disruption the functions of kidneys and liver within human body. Most mining activity of base metal may discharge tailing with a significant lead (Pb content. Lead is a cumulative poison, hence absorbing this element by human body with particularly exceeding its threshold limit value will bind strongly to a large number of molecules such as amino acids, haemoglobin

  10. Electro-Plating and Characterisation of CdTe Thin Films Using CdCl2 as the Cadmium Source

    OpenAIRE

    Nor A. Abdul-Manaf; Hussein I. Salim; Mohammad L. Madugu; Olajide I. Olusola; Imyhamy M. Dharmadasa

    2015-01-01

    Cadmium telluride (CdTe) thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2)·H2O and tellurium dioxide (TeO2) using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD), Raman spectroscopy, optical profilometry, DC current-voltage (I-V) measurements, photoelectrochemical (PEC) cell measurement, scanning electron micr...

  11. Enhanced Cadmium (Cd Phytoextraction from Contaminated Soil using Cd-Resistant Bacterium

    Directory of Open Access Journals (Sweden)

    Kunchaya Setkit

    2014-01-01

    Full Text Available A cadmium (Cd-resistant bacterium, Micrococcus sp. MU1, is able to produce indole-3-acetic acid and promotes root elongation and plant growth. The potential of this bacterium on enhancement of Cd uptake and bioaccumulation of Cd in Helianthus annuus L. planted in Cd-contaminated soil was evaluated in greenhouse condition. The results showed that Micrococcus sp. MU1promoted the growth of H. annuus L. by increasing the root length, stem height, dry biomass, root to shoot ratio and also significantly increased Cd accumulation in the root and above-ground tissues of H. annuus L. compared to uninoculated control. Re-inoculation with Micrococcus sp. MU1in contaminated soil helped in promoting plant growth and Cd phytoextraction throughout the cultivation period. In addition, phytoextraction coefficient and translocation factor (TF of H. annuus L. inoculated with Micrococcus sp. MU1were higher than that of uninoculated control and TF continuously increased with time. Our results suggested that Micrococcus sp. MU1 has an ability to enhance plant growth and Cd uptake in H. annuus L. Synergistic interaction between Micrococcus sp. MU1 and H. annuus L. could be further applied for Cd phytoextraction in polluted areas.

  12. Bioavailability of Cd, Zn and Hg in Soil to Nine Recombinant Luminescent Metal Sensor Bacteria

    Directory of Open Access Journals (Sweden)

    Olesja Bondarenko

    2008-11-01

    Full Text Available A set of nine recombinant heavy metal-specific luminescent bacterial sensors belonging to Gram-negative (Escherichia and Pseudomonas and Gram-positive (Staphylococcus and Bacillus genera and containing various types of recombinant metalresponse genetic elements was characterized for heavy metal bioavailability studies. All nine strains were induced by Hg and Cd and five strains also by Zn. As a lowest limit, the sensors were detecting 0.03 μg·L-1 of Hg, 2 μg·L-1 of Cd and 400 μg·L-1 of Zn. Limit of determination of the sensors depended mostly on metal-response element, whereas the toxicity of those metals towards the sensor bacteria was mostly dependent on the type of the host bacterium, with Gram-positive strains being more sensitive than Gram-negative ones. The set of sensors was used to evaluate bioavailability of Hg, Cd and Zn in spiked soils. The bioavailable fraction of Cd and Zn in soil suspension assay (2.6 – 5.1% and 0.32 – 0.61%, of the total Cd and Zn, respectively was almost comparable for all the sensors, whereas the bioavailability of Hg was about 10-fold higher for Gram-negative sensor cells (30.5% of total Hg, compared to Gram-positive ones (3.2% of the total Hg. For Zn, the bioavailable fraction in soil-water suspensions and respective extracts was comparable (0.37 versus 0.33% of the total Zn. However, in the case of Cd, for all the sensors used and for Hg concerning only Gram-negative sensor strains, the bioavailable fraction in soilwater suspensions exceeded the water-extracted fraction about 14-fold, indicating that upon direct contact, an additional fraction of Cd and Hg was mobilized by those sensor bacteria. Thus, for robust bioavailability studies of heavy metals in soils any type of genetic metal-response elements could be used for the construction of the sensor strains. However, Gram-positive and Gram-negative senor strains should be used in

  13. Bioaccumulation of As, Cd, Cr, Hg(II), and MeHg in killifish (Fundulus heteroclitus) from amphipod and worm prey.

    Science.gov (United States)

    Dutton, Jessica; Fisher, Nicholas S

    2011-08-15

    Elevated metal levels in fish are a concern for the fish themselves, their predators, and possibly humans who consume contaminated seafood. Metal bioaccumulation models often rely on assimilation efficiencies (AEs) of ingested metals and loss rate constants after dietary exposure (k(ef)s). These models can be used to better understand processes regulating metal accumulation and can be used to make site-specific predictions of metal concentrations in animal tissues. Fish often consume a varied diet, and prey choice can influence these two parameters. We investigated the trophic transfer of As, Cd, Cr, Hg(II), and methylmercury (MeHg) from a benthic amphipod (Leptocheirus plumulosus) and an oligochaete (Lumbriculus variegatus) to killifish (Fundulus heteroclitus) using gamma-emitting radioisotopes. Except for MeHg, AEs varied between prey type. AEs were highest for MeHg (92%) and lowest for Cd (2.9-4.5%) and Cr (0.2-4%). Hg(II) showed the largest AE difference between prey type (14% amphipods, 24% worms). For Cd and Hg(II) k(ef)s were higher after consuming amphipods than consuming worms. Tissue distribution data shows that Cd and Hg(II) were mainly associated with the intestine, whereas As and MeHg were transported throughout the body. Calculated trophic transfer factors (TTFs) suggest that MeHg is likely to biomagnify at this trophic step at all ingestion rates, whereas As, Cd, Cr, and Hg(II) will not. Data collected in this study and others indicate that using one prey item to calculate AE and k(ef) could lead to an over- or underestimation of these parameters.

  14. (112)面CdTe/Cd1-yZnyTe,Hg1-xCdxTe/CdTe和CdTe/GaAs异质结的方向倾斜%Oriental Shift at CdTe/Cd1-yZnyTe, Hg1-xCdxTe/CdTe and CdTe/GaAs Heterojunctions Grown on (112) plane

    Institute of Scientific and Technical Information of China (English)

    刘义族; 于福聚

    2001-01-01

    用X射线双晶衍射(XDCD)法测得分子束外延(MBE)法生长的CdTe/Cd0.959Zn0.041Te(112)B异质结的倾斜角为0.2185°,而且朝[1-1-1]晶体学方向倾斜.为了获得较精确的倾斜角值,绘制了外延层和衬底衍射角的差值Δθ与绕样品表面法线旋转的角度φ之间的准正弦函数.为高分辨率透射电子显微镜(HRTEM)分析制备了MBE法生长的Hg0.535Cd0.465Te/CdTe/GaAs(1-12)B多层异质结的横截面薄膜. CdTe/GaAs异质结的HRTEM明场象表明CdTe(1-12)缓冲层相对于GaAs(1-12)衬底朝[1-1 1-]方向倾斜约3°,并且在Hg0.535Cd0.465Te/CdTe异质结,Hg0.535Cd0.465Te(1-12)外延膜相对于CdTe(1-12)缓冲层在[1 1-1]方向,即[1-1 1-]的反方向倾斜约1°.也分析了Hg0.535Cd0.465Te/CdTe/GaAs多层膜之间的倾斜角关系.

  15. Terahertz photoconductivity in GaAs/AlGaAs and HgTe/HgCdTe quantum Hall devices

    Energy Technology Data Exchange (ETDEWEB)

    Stellmach, C.; Bonk, R.; Hirsch, A.; Nachtwei, G. [Institut fuer Angewandte Physik, TU Braunschweig, Mendelssohnstr. 2, 38106 Braunschweig (Germany); Vasilyev, Y.B. [Institut fuer Angewandte Physik, TU Braunschweig, Mendelssohnstr. 2, 38106 Braunschweig (Germany); A.F. Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); Hein, G. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Becker, C.R. [Physikalisches Institut der Universitaet Wuerzburg, 97074 Wuerzburg (Germany)

    2006-08-15

    We present measurements of the THz photoconductivity on different quantum Hall systems. GaAs/AlGaAs and HgTe/HgCdTe (MCT) heterostructures with Hall-bar and Corbino geometry are investigated. A recipe for the preparation of metallic Corbino contacts on MCT is shown. The system is excited by the radiation of a p -Ge laser (tunable from 1.7 to 2.5 THz) and the photoresponse (PR) is measured versus the magnetic field B. We observe enhanced PR around integer filling factors (bolometric PR) and cyclotron resonance (CR) effects. Because of the lower effective mass in MCT, the CR in this system appears at a relatively low magnetic field ({approx}2 T). This is appropriate for possible applications. Finally we present time resolved measurements of the PR on the GaAs system. We find relaxation times from about 10 to over 200 ns, which depend on the geometry, the applied source-drain voltage and the on mobility of the sample. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Investigation of possibility of VLWIR lasing in HgCdTe based heterostructures

    Science.gov (United States)

    Morozov, S. V.; Rumyantsev, V. V.; Kadykov, A. M.; Dubinov, A. A.; Antonov, A. V.; Kudryavtsev, K. E.; Kuritsin, D. I.; Mikhailov, N. N.; Dvoretskii, S. A.; Teppe, F.; Gavrilenko, V. I.

    2015-10-01

    The optical properties of a number of Hg1-xCdxTe bulk epilayers (x = 0.152 - 0.23) and heterostructures with quantum wells (QW) based on narrow gap HgCdTe are examined aiming to reveal the prospects of such structures for laser development in long wave infrared and very long wave infrared ranges. Experimental evidence of long wavelength superluminescence, i.e. amplification of spontaneous emission, at 8.4 μm in narrow gap HgCdTe bulk epitaxial film at 100 K is reported. Employing heterostructures with QW is demonstrated to be promissory for furthering the radiation wavelength to 10 - 30 μm range.

  17. Monolithic dual-band HgCdTe infrared detector structure

    CSIR Research Space (South Africa)

    Parish, G

    1997-07-01

    Full Text Available A monolithic HgCdTe photoconductive device structure is presented that is suitable for dual-band optically registered infrared photodetection in the two atmospheric transmission windows of 3-5 mu m and 8-12 mu m, which correspond to the mid...

  18. Real Time Monitor and Control of MBE Growth of HgCdTe by Spectroscopic Ellipsometry.

    Science.gov (United States)

    2007-11-02

    The primary goal of this contract develop a real-time monitoring capability for HgCdTe composition during MBE growth . This goal was realized by...methodology for acquiring and analyzing insitu SE data in the MBE growth environment. These improvements and developments are part of an extensive

  19. Thermal Cycle Annealing and its Application to Arsenic-Ion Implanted HgCdTe

    Science.gov (United States)

    2014-06-26

    doping profile, as shown in Figure 3. The TCA treatment on the unimplanted epilayers showed an exponential defect reduction proportional to the...Chamonal, P. Castelein, J. Zanatta, M. Tchagaspanian, A. Papon, J. Barnes, F. Henry, S. Gout , G. Bourgeois, C. Pautet and P. Fougeres, "HgCdTe FPAs

  20. Arsenic complexes optical signatures in As-doped HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Gemain, F.; Robin, I. C.; Brochen, S.; Ballet, P.; Gravrand, O.; Feuillet, G. [CEA-LETI Minatec Campus, 17 rue des Martyrs, 38000 Grenoble (France)

    2013-04-08

    In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

  1. The accumulation of heavy metals (Cd, Pb, Hg, Cr) and their state in ...

    African Journals Online (AJOL)

    ONOS

    2010-01-25

    Jan 25, 2010 ... metals (Cd, Pb, Hg and Cr) in the water and plankton of Beysehir and ... In addition, heavy metals show harmful effects ... in laboratory for a period of time for evaporation of water. ...... biochemical effects in an estuarine teleost.

  2. Influence of photoresist feature geometry on ECR plasma-etched HgCdTe trenches

    Science.gov (United States)

    Benson, J. David; Stoltz, Andrew J., Jr.; Kaleczyc, Andrew W.; Martinka, Mike; Almeida, Leo A.; Boyd, Phillip R.; Dinan, John H.

    2002-12-01

    Factors that affect width and aspect ratio in electron cyclotron resonance (ECR) etched HgCdTe trenches are investigated. The ECR etch bias and anisotropy are determined by photoresist feature erosion rate. The physical characteristics of the trenches are attributed to ECR plasma etch chemistry.

  3. STABILITY OF BINARY COMPLEXES OF Pb(II), Cd(II) AND Hg(II ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. Binary complexes of maleic acid with toxic metal ions such as Pb(II), Cd(II) and Hg(II) have been ... By binding the metal ions electrostatically to the negatively charged ..... results in highly stable seven membered rings (Figure 3).

  4. Development of megapixel HgCdTe detector arrays with 15 micron cutoff

    Science.gov (United States)

    Forrest, William J.; McMurtry, Craig W.; Dorn, Meghan; Pipher, Judith; Cabrera, Mario S.

    2016-10-01

    I. HistoryHgCdTe is a versatile II-VI semiconductor with a direct-bandgap tunable via the Hg:Cd ratio. Hg:Cd ratio = 53:47 (2.5 micron cutoff) was used on the NICMOS instrument on HST and the 2MASS. Increasing Hg:Cd ratio to 70:30 leads to a 5.4 micron cutoff, utilized in NEOWISE and many JWST instruments. Bailey, Wu et al. (1998) motivated extending this technology to 10 microns and beyond. Bacon, McMurtry et al. (2003, 2004) indicated significant progress toward this longwave (LW) goal.Warm-Spitzer has pioneered passive cooling to below 30 K in space, enabling the JWST mission.II. CurrentNASA's proposed NEOcam mission selected HgCdTe with a 10.6 micron cutoff because it promises natural Zodiacal background limited sensitivity with modest cooling (40 K). Teledyne Imaging Systems (TIS) is producing megapixel arrays with excellent performance (McMurtry, Lee, Dorn et al. (2013)) for this mission.III. FutureModest cooling requirements (circa 30 K) coupled with megapixel arrays and LW sensitivity in the thermal IR make HgCdTe attractive for many infrared instruments. For instance, the spectral signature of a terrestrial planet orbiting in the habitable zone of a nearby star will be the deep and wide absorption by CO_2 centered at 15 microns (Seager and Deming, 2010). LW instruments can enhance Solar System missions, such as exploration of the Enceladus geysers (Spencer, Buratti et al. 2006). Passive cooling will be adequate for these missions. Modern ground-based observatories will benefit from infrared capability out to the N band (7.5-13.6 microns). The required detector temperatures (30-40 K) are easily achievable using commercially available mechanical cryo-coolers (refrigerators).IV. Progress to dateTIS is developing megapixel HgCdTe arrays sensitive out to 15 microns under the direction of the University of Rochester. As a first step, we have produced arrays with a 13 micron cutoff. The initial measurements indicate very promising performance. We will present the

  5. Studies on photoinduced effects in pulse-electrodeposited Ag/Hg-1212/CdSe hetero-nanostructures

    Indian Academy of Sciences (India)

    D D Shivagan; P M Shirage; S H Pawar

    2002-05-01

    Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined. The increase in carrier concentration across the junction due to photo-irradiation has been observed.

  6. Real-Time Monitoring and Control of HgCdTe MBE Using an Integrated Multi-Sensor System

    Science.gov (United States)

    1998-08-01

    layer composition, and effusion cell flux during MBE growth of HgCdTe epilayers for advanced IR detectors. Substrate temperature is measured and...HgCdTe MBE growth of high performance IR detector structures over a wide range of compositions, layer thickness and substrate temperature.

  7. Optical transmittance properties for CdS films in CdTe-HgCdTe tandem solar cells%CdTe-HgCdTe叠层太阳电池CdS窗口层透射光谱性能研究

    Institute of Scientific and Technical Information of China (English)

    郭珉; 朱秀荣; 李贺军

    2016-01-01

    Improving the spectral transmittance of CdS window layer used in CdTe-HgCdTe tandem solar cells has a significant impact on the effective utilization of sunlight and increases the device short-circuit current density(Jsc). Herein, the average transmittance(T) and Jsc losses of as-deposited and CdCl2 annealed CdS films prepared by chemical bath deposition ( CBD ) , near space sublimation ( CSS ) and magnetron sputtering(SPUT) are studied. The results show that: in the range of 520-820 nm, the as-deposited and annealed CdS films by CBD exhibit the highest T and the lowest Jsc losses of the CdTe top cell; in the range of 820-1 150 and 520-1 150 nm, the as-deposited and annealed CdS films by SPUT exhibit the highest T and the lowest Jsc losses of the HgCdTe bottom cell and the CdTe-HgCdTe tandem solar cells. In the range of 520-820, 820-1 150 and 520-1 150 nm, the CdCl2 annealing can greatly increase T of CdS films and decrease the Jsc losses of the CdTe top cell, the HgCdTe bottom cell and the CdTe-HgCdTe tandem solar cells.%CdS窗口层光谱透射率的提高对CdTe-HgCdTe叠层太阳电池有效利用入射太阳光并增大电池的短路电流密度有重要的影响。通过研究化学水浴法、近空间升华法和磁控溅射法制备的CdS薄膜在CdCl2退火前后的光谱平均透过率和短路电流密度损失表明:在光谱区520~820 nm,化学水浴法制备的CdS薄膜在退火前后具有最高的光谱平均透过率,对应的CdTe顶电池有最小的短路电流密度损失;在光谱区820~1150和520~1150 nm,磁控溅射法制备的CdS薄膜在退火前后均具有最高的光谱平均透过率,对应的HgCdTe底电池和CdTe-HgCdTe叠层太阳电池有最小的短路电流密度损失。在光谱区520~820、820~1150和520~1150 nm,CdCl2退火可以显著增大CdS薄膜的光谱平均透过率,降低对应CdTe顶电池、HgCdTe底电池和CdTe-HgCdTe叠层电池的短路电流密度损失。

  8. Responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil.

    Science.gov (United States)

    Yan, Chong Ling; Lin, Peng; Wang, Xiao Rong

    2002-09-01

    Pot experiment was used to study the responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil. The results showed that POD activity gradually increased with increasing concetrations of Hg, Cd and Pb. CAT and SOD activity gradually decreased under three heavy metals common existing and SOD variation curve showed unimodal curve under single or two elements existing with increase of concentration of Hg, Cd and Pb. The effects of Hg, Cd and Pb in soil: three elemets together > two elements together > single element only. The effects resulted in an imbalance--activated oxygen produce and scavenge and physiological biochemical process disorder. There was a synergistic action for the effect of Hg, Cd and Pb in soil on membrane protection enzyme system in tobacco leaves.

  9. Investigation of Substrate Effects on Interface Strain and Defect Generation in MBE-Grown HgCdTe

    Science.gov (United States)

    Gu, R.; Lei, W.; Antoszewski, J.; Faraone, L.

    2016-09-01

    Si, Ge, and GaAs have been extensively investigated as alternative substrates for molecular-beam epitaxy (MBE) growth of HgCdTe and, at present, are widely used for HgCdTe-based infrared focal-plane arrays. However, the problem of high dislocation density in HgCdTe layers grown on these lattice-mismatched substrates has yet to be resolved. In this work, we investigated another alternative substrate, GaSb, which has a significantly smaller lattice mismatch with HgCdTe in comparison with Si, Ge, and GaAs, and is readily available as large-area, epiready wafers at much lower cost in comparison with lattice-matched CdZnTe substrates. The resultant stress due to lattice and thermal mismatch between the HgCdTe epilayer and various substrates has been calculated in this work using the elasticity matrix, and the corresponding stress distribution simulated using ANSYS. The simulated structures were matched by experimental samples involving MBE growth of HgCdTe on GaAs, GaSb, and CdZnTe substrates, and were characterized via reflection high-energy electron diffraction and x-ray diffraction analysis, followed by etch pit density (EPD) analysis. In comparison with other alternative substrates, GaSb is shown to have lower interface stress and lower EPD, rendering it an interesting and promising alternative substrate material for HgCdTe epitaxy.

  10. HgTe/CdHgTe double quantum well with a spectrum of bilayer graphene and peculiarities of its magnetotransport

    Science.gov (United States)

    Yakunin, M. V.; Krishtopenko, S. S.; Podgornykh, S. M.; Popov, M. R.; Neverov, V. N.; Mikhailov, N. N.; Dvoretsky, S. A.

    2016-09-01

    The quantum Hall effect (QHE) in a HgTe/CdHgTe double quantum well (DQW) with a tunneling-transparent barrier and the energy spectrum resembling the band structure of bilayer graphene has been investigated. An experimental manifestation of a tunnel gap between the states of light carriers seen as a magnetoresistance (MR) peak in the in-plane magnetic field has been discovered. An unusual structure of the QHE has been observed in a sample with hole conductivity: there is a pronounced peak on a plateau with the number i = 2 and the slopes of this anomalous peak correspond to two peaks of the longitudinal MR. On the other hand, a stable 2-1 plateau-plateau transition has been observed in much higher fields with the position of this transition corresponding to a considerably higher hole density than follows from the pattern of the QHE in weak fields. The anomalous peak is interpreted as a reentrant QHE between the 2-1-2 states. The position of the anomalous peak is immune to IR illumination and the tilting angle of the magnetic field, although these factors strongly affect its amplitude. According to comparison with the calculated structure of magnetic levels, the anomalous peak is attributed to crossing of electron-like and hole-like levels in the valence band. The difference between the hole densities found in weak field and from the 2-1 transition in strong fields is attributed to the effects of redistribution of holes between the localized states in sideband maxima of the valence subband and the ones delocalized in the overlapping levels of light holes.

  11. Recent progress in the doping of MBE HgCdTe

    Science.gov (United States)

    Sivananthan, Sivalingam; Wijewarnasuriya, P. S.; Faurie, Jean-Pierre

    1995-09-01

    We present a review of the recent progress in the doping of HgCdTe grown by molecular beam epitaxy. A detailed analysis of the unintentional/intrinsic, n-type, and p-type doping is presented. Our results show that CdZnTe substrates should be carefully screened to reduce the out-diffusion of impurities from the substrate. N-type HgCdTe layers exhibit excellent Hall characteristics down to indium levels of 2 X 10(superscript 15) cm(superscript -3). Electron mobilities in the range of (2 - 3) X 10(superscript 5) cm(superscript 2)/vs at 23 K were obtained. Measured lifetime data fits very well with the intrinsic band-to-band recombination. However, below 2 X 10(superscript 15) cm(superscript -3) doping levels, minority carrier lifetime is limited by Schockley-Reed recombination. We have implemented planar doping with arsenic as p-type dopant during MBE growth. Our results clearly indicate that arsenic incorporates as an acceptor dopant during the growth of MBE HgCdTe.

  12. Proton irradiation results for long-wave HgCdTe infrared detector arrays for NEOCam

    CERN Document Server

    Dorn, M; McMurtry, C; Hartman, S; Mainzer, A; McKelvey, M; McMurray, R; Chevara, D; Rosser, J

    2016-01-01

    HgCdTe detector arrays with a cutoff wavelength of ~10 ${\\mu}$m intended for the NEOCam space mission were subjected to proton beam irradiation at the University of California Davis Crocker Nuclear Laboratory. Three arrays were tested - one with 800 $\\mu$m substrate intact, one with 30 $\\mu$m substrate, and one completely substrate-removed. The CdZnTe substrate, on which the HgCdTe detector is grown, has been shown to produce luminescence in shorter wave HgCdTe arrays that causes elevated signal in non-hit pixels when subjected to proton irradiation. This testing was conducted to ascertain whether or not full substrate removal is necessary. At the dark level of the dewar, we detect no luminescence in non-hit pixels during proton testing for both the substrate-removed detector array and the array with 30 ${\\mu}$m substrate. The detector array with full 800 ${\\mu}$m substrate exhibited substantial photocurrent for a flux of 103 protons/cm$^2$-s at a beam energy of 18.1 MeV (~ 750 e$^-$/s) and 34.4 MeV ($\\sim$ 6...

  13. Cross-Sectional Study of Macrodefects in MBE Dual-Band HgCdTe on CdZnTe

    Science.gov (United States)

    Reddy, M.; Lofgreen, D. D.; Jones, K. A.; Peterson, J. M.; Radford, W. A.; Benson, J. D.; Johnson, S. M.

    2013-11-01

    HgCdTe dual-band mid-wave infrared/long-wave infrared focal-plane arrays on CdZnTe are a key component in advanced electrooptic sensor applications. Molecular beam epitaxy (MBE) has been used successfully for growth of dual-band layers on larger CdZnTe substrates. However, the macrodefect density, which is known to reduce the pixel operability and its run-to-run variation, is larger when compared with layers grown on Si substrate. This paper reports the macrodefect density versus size signature of a well-optimized MBE dual-band growth and a cross-sectional study of a macrodefect that represents the most prevalent class using focused ion beam, scanning transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The results show that the macrodefect originates from a void, which in turn is associated with a pit on the CdZnTe substrate.

  14. Investigation of magnetoabsorption at different temperatures in HgTe/CdHgTe quantum-well heterostructures in pulsed magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, V. V.; Kudasov, Yu. B.; Makarov, I. V.; Maslov, D. A.; Surdin, O. M. [Sarov Physical–Technical Institute—National Research Nuclear University MEPhI (Russian Federation); Zholudev, M. S.; Ikonnikov, A. V.; Gavrilenko, V. I. [Russian Academy of Sciences, Institute of Physics of Microstructures (Russian Federation); Mikhailov, N. N.; Dvoretsky, S. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-12-15

    The magnetoabsorption in magnetic fields as high as 40 T is investigated at T > 77 K in HgTe/CdHgTe quantum-well heterostructures (d{sub QW} ≈ 8 nm). The spectra reveal two lines associated both with intraband transition from the lower Landau level in the conduction band and with interband transition. It is shown that the band structure in these systems changes from inverted to normal with increasing temperature.

  15. The Liquid-Liquid Extraction of Toxic Metals (Cd, Hg and Pb by Calixarenes

    Directory of Open Access Journals (Sweden)

    D. Max Roundhill

    2009-12-01

    Full Text Available Toxic metals (Cd, Hg and Pb are mostly present in the environment due to natural phenomenon and human activities as well. Exposure of these non-essential elements in the environment causes severe effects. They are known to cause problems in humans as well as in aquatic life. In this work, we demonstrate various studies regarding liquid-liquid extraction of selected ions with different functionalized calixarenes. This review article briefly discusses several molecular designs of calixarenes for divalent ion (Cd2+, Hg2+ and Pb2+ recognition; as well as the relationship between structure and selectivity of the macrocycles is elaborated. The article does not, however, attempt to cover all of the different approaches to these toxic metal ions extraction.

  16. Linear Mode HgCdTe Avalanche Photodiodes for Photon Counting Applications

    Science.gov (United States)

    Sullivan, William, III; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

    2015-01-01

    An overview of recent improvements in the understanding and maturity of linear mode photon counting with HgCdTe electron-initiated avalanche photodiodes is presented. The first HgCdTe LMPC 2x8 format array fabricated in 2011 with 64 micron pitch was a remarkable success in terms of demonstrating a high single photon signal to noise ratio of 13.7 with an excess noise factor of 1.3-1.4, a 7 ns minimum time between events, and a broad spectral response extending from 0.4 micron to 4.2 micron. The main limitations were a greater than 10x higher false event rate than expected of greater than 1 MHz, a 5-7x lower than expected APD gain, and a photon detection efficiency of only 50% when greater than 60% was expected. This paper discusses the reasons behind these limitations and the implementation of their mitigations with new results.

  17. High precision strain mapping of topological insulator HgTe/CdTe

    Science.gov (United States)

    Haas, Benedikt; Thomas, Candice; Jouneau, Pierre-Henri; Bernier, Nicolas; Meunier, Tristan; Ballet, Philippe; Rouvière, Jean-Luc

    2017-06-01

    Topological insulators (TIs) represent a class of matter associated with unique electronic and spin properties held by chiral and massless Dirac fermions. The lattice mismatch between the HgTe layer and the CdTe substrate, which is the reason for the TI properties in HgTe/CdTe, is less than 0.4%. Measuring it necessitates an extremely sensitive technique, while a nanometric spatial resolution is mandatory to characterize the strain gradient across the layers. In this letter, we demonstrate the use of nano-beam precession electron diffraction to map the strain of the whole stack, thus experimentally addressing the strain distribution in such systems. Strain maps with a precision of 0.03% and a spatial resolution of 1.9 nm show good agreement with finite element simulations of the expected strain. Strain values and gradients are within the intervals predicted to yield the TI properties of the material.

  18. Dislocation Reduction of HgCdTe/Si Through Ex Situ Annealing

    Science.gov (United States)

    2016-06-07

    position, policy or decision, unless so designated by other documentation. 12. DISTRIBUTION AVAILIBILITY STATEMENT Approved for public release; distribution...967 mercury overpressure needed to maintain the surface morphologies and composition of HgCdTe, a cap layer of ZnTe or ZnSe was used for these...proper surface morphology could be main- tained. The cycle annealing process was also com- pared with our standard device annealing process in terms of

  19. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    Science.gov (United States)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  20. Update on Linear Mode Photon Counting with the HgCdTe Linear Mode Avalanche Photodiode

    Science.gov (United States)

    Beck, Jeffrey D.; Kinch, Mike; Sun, Xiaoli

    2014-01-01

    The behavior of the gain-voltage characteristic of the mid-wavelength infrared cutoff HgCdTe linear mode avalanche photodiode (e-APD) is discussed both experimentally and theoretically as a function of the width of the multiplication region. Data are shown that demonstrate a strong dependence of the gain at a given bias voltage on the width of the n- gain region. Geometrical and fundamental theoretical models are examined to explain this behavior. The geometrical model takes into account the gain-dependent optical fill factor of the cylindrical APD. The theoretical model is based on the ballistic ionization model being developed for the HgCdTe APD. It is concluded that the fundamental theoretical explanation is the dominant effect. A model is developed that combines both the geometrical and fundamental effects. The model also takes into account the effect of the varying multiplication width in the low bias region of the gain-voltage curve. It is concluded that the lower than expected gain seen in the first 2 × 8 HgCdTe linear mode photon counting APD arrays, and higher excess noise factor, was very likely due to the larger than typical multiplication region length in the photon counting APD pixel design. The implications of these effects on device photon counting performance are discussed.

  1. Density, Electrical Conductivity and Viscosity of Hg(0.8)Cd(0.2)Te Melt

    Science.gov (United States)

    Li, C.; Scripa, R. N.; Ban, H.; Su, C.-H.; Lehoczky, S. L.

    2004-01-01

    The density, viscosity, and electrical conductivity of Hg(0.8)Cd(0.2)Te melt were measured as a function of temperature. A pycnometric method was used to measure the melt density in the temperature range of 1072 to 1122 K. The viscosity and electrical conductivity were determined using a transient torque method from 1068 to 1132 K. The density result from this study is within 0.3% of the published data. However, the current viscosity result is approximately 30% lower than the existing data. The electrical conductivity of Hg(0.8)Cd(0.2)Te melt as a function of temperature, which is not available in the literature, is also determined. The analysis of the temperature dependent electrical conductivity and the relationship between the kinematic viscosity and density indicated that the structure of the melt appeared to be homogeneous when the temperature was above 1090 K. A structural transition occurred in the Hg(0.8)Cd(0.2)Te melt as the temperature was decreased to below 1090 K

  2. Candidate 10 micron HgCdTe arrays for the NEOCam space mission

    Science.gov (United States)

    McMurtry, Craig W.; Dorn, Meghan; Cabrera, Mario S.; Pipher, Judith L.; Forrest, William J.; Mainzer, Amy K.; Wong, Andre

    2016-08-01

    The Near Earth Object Camera (NEOCam, Mainzer et al. 2015) is one of five NASA Discovery Class mission experiments selected for Phase A: down-select to one or two experiments will take place late in 2016. NEOCam will survey the sky in search of asteroids and comets, particularly those close to the Earth's orbit. The NEOCam infrared telescope will have two infrared (IR) channels; one covering 4 to 5 microns, and one covering 6-10 microns. Both IR cameras will use multiple 2Kx2K pixel format HAWAII-2RG arrays with different cutoff wavelength HgCdTe detectors from Teledyne Imaging Sensors. Past development work by the University of Rochester with Teledyne Imaging Sensors and JPL (McMurtry et al. 2013, Dorn et al. 2016) focused upon bringing the 10 micron HgCdTe detector technology up to NASA TRL 6+. This work extends that development program to push the format from 1Kx1K to the larger 2Kx2K pixel array. We present results on the first 2Kx2K candidate 10 micron cutoff HgCdTe arrays, where we measured the dark current, read noise, and total noise.

  3. Update on Linear Mode Photon Counting with the HgCdTe Linear Mode Avalanche Photodiode

    Science.gov (United States)

    Beck, Jeffrey D.; Kinch, Mike; Sun, Xiaoli

    2014-01-01

    The behavior of the gain-voltage characteristic of the mid-wavelength infrared cutoff HgCdTe linear mode avalanche photodiode (e-APD) is discussed both experimentally and theoretically as a function of the width of the multiplication region. Data are shown that demonstrate a strong dependence of the gain at a given bias voltage on the width of the n- gain region. Geometrical and fundamental theoretical models are examined to explain this behavior. The geometrical model takes into account the gain-dependent optical fill factor of the cylindrical APD. The theoretical model is based on the ballistic ionization model being developed for the HgCdTe APD. It is concluded that the fundamental theoretical explanation is the dominant effect. A model is developed that combines both the geometrical and fundamental effects. The model also takes into account the effect of the varying multiplication width in the low bias region of the gain-voltage curve. It is concluded that the lower than expected gain seen in the first 2 × 8 HgCdTe linear mode photon counting APD arrays, and higher excess noise factor, was very likely due to the larger than typical multiplication region length in the photon counting APD pixel design. The implications of these effects on device photon counting performance are discussed.

  4. Accumulation and tolerance characteristics of cadmium in a halophytic Cd-hyperaccumulator, Arthrocnemum macrostachyum

    Energy Technology Data Exchange (ETDEWEB)

    Redondo-Gomez, Susana, E-mail: susana@us.es [Departamento de Biologia Vegetal y Ecologia, Facultad de Biologia, Universidad de Sevilla, Apartado 1095, 41080 Sevilla (Spain); Mateos-Naranjo, Enrique; Andrades-Moreno, Luis [Departamento de Biologia Vegetal y Ecologia, Facultad de Biologia, Universidad de Sevilla, Apartado 1095, 41080 Sevilla (Spain)

    2010-12-15

    The potential of the extreme halophyte Arthrocnemum macrostachyum was examined to determine its tolerance and ability to accumulate cadmium for phytoremediation purposes. A glasshouse experiment was designed to investigate the effect of cadmium from 0 to 1.35 mmol l{sup -1} on the growth and the photosynthetic apparatus of A. macrostachyum by measuring chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. We also determined ash, cadmium, calcium, copper, iron, manganese, magnesium, phosphorous, sodium, and zinc concentrations, and C/N ratio. A. macrostachyum demonstrated hypertolerance to cadmium stress; it did not show phytotoxicity at shoot concentration as high as 70 mg kg{sup -1}. The bioaccumulator factors exceeded the critical value (1.0) for all Cd treatments, and the transport factors indicated that this species has higher ability to transfer Cd from roots to shoots at lower Cd concentrations. At 1.35 mmol l{sup -1} Cd A. macrostachyum showed 25% biomass reduction after a month of treatment. Long-term effects of cadmium on the growth were mainly determined by variations in net photosynthetic rate (P{sub N}). Reductions in P{sub N} could be accounted by higher dark respiration and lower pigment concentrations. Finally, A. macrostachyum has the basic characteristics of a Cd-hyperaccumulator and may be useful for restoring Cd-contaminated sites.

  5. Heavy metal levels (Pb, Cd, Cr and Hg) in the adult general population near an urban solid waste incinerator.

    Science.gov (United States)

    Zubero, Miren Begoña; Aurrekoetxea, Juan José; Ibarluzea, Jesús María; Arenaza, Maria Jesús; Rodríguez, Carlos; Sáenz, José Ramón

    2010-09-15

    In 2005 an urban solid waste incinerator (SWI) was commissioned in Bilbao (Basque Country, Spain). Serum and urine samples were collected from 95 and 107 volunteers in 2006 and 2008 respectively, of which 62 were repeats from the same individuals. Blood lead levels (BPb) were determined, as were the concentrations of cadmium (Cd), chromium (Cr) and mercury (Hg) in urine (UCd, UCr and UHg). The town of Alonsotegi and a borough of Bilbao (Altamira, Rekalde) were considered to be close, less than 2 km from the plant, and correspond to an urban environment with high traffic density. The areas of reference were a borough of Bilbao (Santutxu-Zurbaran), 5 km from the plant, also in an urban area with high traffic density, and a small town with little industrial activity and low traffic density (Balmaseda) 20 km from the plant; neither of these is downwind from the site with respect to prevailing winds. There was a significant correlation for BPb, r=0.63 (p0.05). Multiple linear regression models did not show increases over time of the levels of BPb, UCd, UCr and UHg in the areas close to the SWI compared to those of areas located further away, after adjusting for confounding variables. These results reinforce the hypothesis that populations near modern plants for solid waste incineration do not manifest increased levels of heavy metals. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Development of non-hybridised HgCdTe detectors for the next generation of astronomical instrumentation

    Science.gov (United States)

    Dalton, Gavin B.; Dennis, Peter N.; Lees, David J.; Hall, David J.; Cairns, John W.; Gordon, Neil T.; Hails, Janet E.; Giess, Jean

    2008-07-01

    The superb image quality that is predicted, and even demanded, for the next generation of Extremely Large Telescopes (ELT) presents a potential crisis in terms of the sheer number of detectors that may be required. Developments in infrared technology have progressed dramatically in recent years, but a substantial reduction in the cost per pixel of these IR arrays will be necessary to permit full exploitation of the capabilities of these telescopes. Here we present an outline and progress report of an initiative to develop a new generation of astronomical grade Cadmium Mercury Telluride (HgCdTe) array detectors using a novel technique which enables direct growth of the sensor diodes onto the Read Out Integrated Circuit (ROIC). This technique removes the need to hybridise the detector material to a separate Silicon readout circuit and provides a route to very large monolithic arrays. We present preliminary growth and design simulation results for devices based on this technique, and discuss the prospects for deployment of this technology in the era of extremely large telescopes.

  7. Accumulation and localization of cadmium in potato (Solanum tuberosum) under different soil Cd levels.

    Science.gov (United States)

    Chen, Zhifan; Zhao, Ye; Gu, Lei; Wang, Shuifeng; Li, Yongliang; Dong, Fangli

    2014-06-01

    Phytoavailability and uptake mechanism of Cd in edible plant tissues grown on metal polluted agricultural soils has become a growing concern worldwide. Uptake, transport, accumulation and localization of cadmium in potato organs under different soil Cd levels were investigated using inductively-coupled plasma mass spectrometry and energy dispersive X-ray microanalysis. Results indicated that Cd contents in potato organs increased with increasing soil Cd concentrations, and the order of Cd contents in different organs was leaves > stems/roots > tubers. Root-to-stem Cd translocation coefficients ranged from 0.89 to 1.81. Cd localization in potato tissues suggested that leaves and stems should be the main compartment of Cd storage and uptake. Although low concentrations of Cd migrated from the root to tuber, Cd accumulation in the tuber exceeded the standard for food security. Therefore, the planting of potato plants in farmland containing Cd should be closely evaluated due to its potential to present health risks.

  8. Valve movement response of the mussel mytilus galloprovincialis to metals (Cu, Hg, Cd and Zn) and phosphate industry effluents from Moroccan Atlantic coast.

    Science.gov (United States)

    Fdil, Mohamed Ait; Mouabad, Abdelfattah; Outzourhit, Abdelkader; Benhra, Ali; Maarouf, Abdelmalek; Pihan, Jean Claude

    2006-07-01

    Valve activity was measured in the Mediterranean mussel Mytilus galloprovincialis in response to sublethal concentrations of four metals (Hg, Cu, Zn and Cd) and two phosphate industry effluents from the Atlantic coast of Morocco. Valve movements were monitored using a proximity inductive sensor which could display all activity figures from full closure to wide opening of the shell valves. In a 1 h exposure experiments, all metals induced a decrease in the time of normal opening and the appearance of sequences of stress behaviour, including enhanced valve adductions and complete closure at high concentrations. Mercury (tested from 5 to 75 microg Hg l(-1)) was the most toxic to the valve activity, with a threshold effective concentration at 10 microg Hg l(-1) and full valve closure occurring at 50 microg Hg l(-1). Copper (15-150 microg Cu l(-1)) showed a toxic effect starting at threshold concentration of 20 microg Cu l(-1) and induced full valve closure at 150 microg Cu l(-1). Zinc (100-500 microg Zn l(-1)) was effective in reducing the time of normal opening (threshold concentration at 100 microg Zn I(-1)) but no complete closure was recorded in any of the tested concentrations. For cadmium (1000-5000 microg Cd l(-1)), the valve activity was insensitive for exposures under 2000 microg Cd l(-1). Results for the testing of several samplings of the phosphate industry effluents (Safi and Jorf Lasfar) showed that their toxicity varied over the time. The effluent of the Jorf Lasfar plant (2-9.4%) was, however, more toxic than that of Safi (1-25%). In the light of these results, the sensitivity of the valve activity of Mytilus galloprovincialis to pollutants and its usefulness for in situ monitoring of coastal pollution in Morocco are discussed.

  9. Separation of cadmium and nickel from waste Ni-Cd batteries

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    To separate the cadmium and nickel resources in waste Ni-Cd batteries, a self-designed vacuum distillation recycling system was studied under laboratory conditions. The effects of system temperature, operating pressure, and time on the separation of Ni and Cd were studied respectively. The mechanism of vacuum thermal recycling was also discussed. Results show that vacuum distillation is a very effective separation method for waste Ni-Cd batteries. At a constant pressure, the increase of temperature can improve the separating efficiency of Cd. When the temperature is 1 173K, cadmium can evaporate completely from the samples during 3 h at 10 Pa. The reduction of pressure in a certain range is effective to the separating of Cd from Ni-Cd batteries by vacuum distillation.

  10. Mechanical properties and material removal characteristics of soft-brittle HgCdTe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Irwan, R. [School of Mechanical and Mining Engineering, the University of Queensland, Brisbane, QLD 4072 (Australia); Huang, H., E-mail: han.huang@uq.edu.au [School of Mechanical and Mining Engineering, the University of Queensland, Brisbane, QLD 4072 (Australia); Zheng, H.Y.; Wu, H. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore)

    2013-01-01

    Mechanical properties and material removal characteristics of mercury cadmium telluride (Hg{sub 0.84}C{sub 0.16}Te) single crystals were investigated by the use of indentation and single point diamond turning. The nanoindentation tests showed that the average values of elastic modulus and hardness were 40 and 0.55 GPa, respectively. The fracture toughness estimated by Vickers indentation fracture toughness test was 0.200 MPa m{sup 1/2}, in the predicted range of 0.204-0.235 MPa m{sup 1/2} by the Bifano model. The diamond turning experiments revealed that there was a threshold value in depth of cut that was responsible for the transition from ductile to brittle removal modes during the cutting of the Hg{sub 0.84}C{sub 0.16}Te single crystals. The measured critical depth of cut was between 1.5 and 2 {mu}m, in agreement with that of 1.541 {mu}m calculated by the Bifano model.

  11. HgCdTe Infrared Avalanche Photodiode Single Photon Detector Arrays for the LIST and Other Decadal Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop a HgCdTe avalanche photodiode (APD)  SWIR/IR linear mode photon counting (LMPC) array detector system in support of the LIST lidar. Provide a new type...

  12. RESPONSES OF MEMBRANE PROTECTION ENZYME SYSTEM OF TOBACCO LEAVES ON Hg, Cd AND Pb STRESSES IN SOIL%烟草叶片膜保护酶系统对土壤Hg,Cd,Pb胁迫的响应

    Institute of Scientific and Technical Information of China (English)

    严重玲; 林鹏; 王晓蓉

    2002-01-01

    采用盆栽实验,就烟草膜保护酶系统对土壤Hg,Cd,Pb胁迫的响应进行研究.结果表明:随着Hg,Cd,Pb浓度的增加,POD活性逐渐增加,CAT活性逐渐减小,SOD活性在三种元素共同作用时逐渐下降,在元素单一或两两作用时,SOD活性呈单峰曲线,但总体水平仍较低.土壤Hg,Cd,Pb的这种影响表现出三元素共同作用>两两元素作用>单一元素作用.影响的结果造成活性氧产生与清除之间的不平衡,致使相关生理生化过程紊乱.三种重金属对烟草活性氧清除系统的影响表现出明显地协同作用.%Pot experiment was used to study the responses of membrane protection enzyme system of tobac-co loves on Hg, Cd and Pb stresses in soil. The results showed that POD activity gradually increased with in-creasing concetrations of Hg, Cd and Pb. CAT and SOD activity gradually decreased under three heavy metalscommon existing and SOD variation curve showed unimodal curve under single or two elements existing withincrease of concentration of Hg, Cd and Pb. The effects of Hg, Cd and Pb in soil: three elemets together>twoelements together>single element only. The effects resulted in an imbalance -- activated oxygen produce andscavenge and physiological biochemical process disorder. There was a synergistic action for the effect of Hg, Cdand Pb in soil on membrane protection enzyme system in tobacco leaves.

  13. Size distribution effects of cadmium tellurium quantum dots (CdS/CdTe) immunotoxicity on aquatic organisms.

    Science.gov (United States)

    Bruneau, A; Fortier, M; Gagne, F; Gagnon, C; Turcotte, P; Tayabali, A; Davis, T L; Auffret, M; Fournier, M

    2013-03-01

    The increasing use of products derived from nanotechnology has raised concern about their potential toxicity to aquatic life. This study sought to examine the comparative immunotoxicity of capped cadmium sulphide/cadmium telluride (CdS/CdTe) quantum dots (QDs) and possible impact of particle/aggregate size on two bivalves (Mytilus edulis and Elliptio complanata) and a fish (Oncorhynchus mykiss). The QDs were dispersed in sterile water and fractionated using a series of micro/ultrafiltration membranes of decreasing pore size: 450 nm, 100 nm, 50 nm, 25 nm, 100 kDa (6.8 nm), 30 kDa (4.6 nm), 10 kDa (3.2 nm) and 1 kDa (1.5 nm). The total concentrations of cadmium and tellurium were determined for the filtered material and for that retained on the filters (retentate). The immunotoxicity was determined by measuring cell viability and phagocytosis. Results revealed that nanoparticles retained on the ultrafilters had a higher Cd/Te ratio compared to the permeate fraction (ratio of 5 and 2 respectively) which could indicate that the CdS core was not associated with the permeable fraction of Cd. Our results demonstrate that the toxicity of CdS/CdTe QDs was concentration and size dependent. Large CdS/CdTe QD aggregates (25 nm < size < 100 nm) reduced phagocytosis more than did smaller nanoparticles (<25 nm). Moreover, our results revealed that the different species responded differently to these fractions. Mytilus edulis hemocytes were less sensitive to CdS/CdTe QDs than the Oncorhynchus mykiss macrophage and Elliptio complanata hemocytes.

  14. Growth and characterization of Hg(1-x)Cd(x)Se alloys

    Science.gov (United States)

    Andrews, R. N.; Szofran, F. R.; Lehoczky, S. L.

    1988-01-01

    A detailed evaluation of the influence of growth conditions on the radial and axial compositional variations in directionally solidified Hg(1-x)Cd(x)Se alloys was performed. The measured axial compositional profiles were fitted to theoretical profiles to determine the effective solute (CdSe) diffusion coefficient (D) for the Hg(1-x)Cd(x)Se system. The value for D was estimated to be 3.0 + or - 0.5 x 10 to the -5th sq cm/s and did not appear to be significantly affected by the rate of crystal growth. The axial crystal uniformity was shown to be highly growth-rate dependent, with the faster growth rates producing crystals of more uniform composition in the axial direction. The magnitude of the radial variations was also shown to be highly growth-rate dependent, with the slower growth rates producing crystals of greater radial uniformity. This translation rate dependence of the radial uniformity is discussed in terms of lateral solute diffusion and convective interfacial fluid flows.

  15. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  16. High-Performance MWIR HgCdTe on Si Substrate Focal Plane Array Development

    Science.gov (United States)

    Bommena, R.; Ketharanathan, S.; Wijewarnasuriya, P. S.; Dhar, N. K.; Kodama, R.; Zhao, J.; Buurma, C.; Bergeson, J. D.; Aqariden, F.; Velicu, S.

    2015-09-01

    The development of low noise-equivalent differential temperature (NEDT), high-operability midwave infrared (MWIR) focal plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates is reported. High-quality n-type MWIR HgCdTe layers with a cutoff wavelength of 4.90 μm at 77 K and a carrier concentration of 1-2 × 1015 cm-3 were grown on CdTe/Si substrates by MBE. Highly uniform composition and thickness over 3-inch areas were demonstrated, and low surface defect densities (voids ~5 × 102 cm-2, micro-defects ~5 × 103 cm-2) and etch pit density (~3.5 × 106 cm-2) were measured. This material was used to fabricate 320 × 256, 30 μm pitch FPAs with planar device architecture; arsenic implantation was used to achieve p-type doping. Radiometric and noise characterization was also performed. A low NEDT of 13.8 m K at 85 K for a 1 ms integration time with f/#2 optics was measured. The NEDT operability was 99% at 120 K with a mean dark current noise of 8.14 × 10-13 A/pixel. High-quality thermal images were obtained from the FPA up to a temperature of 150 K.

  17. Characterization of HgCdTe Films Grown on Large-Area CdZnTe Substrates by Molecular Beam Epitaxy

    Science.gov (United States)

    Arkun, F. Erdem; Edwall, Dennis D.; Ellsworth, Jon; Douglas, Sheri; Zandian, Majid; Carmody, Michael

    2017-09-01

    Recent advances in growth of Hg1- x Cd x Te films on large-area (7 cm × 7.5 cm) CdZnTe (CZT) substrates is presented. Growth of Hg1- x Cd x Te with good uniformity on large-area wafers is achieved using a Riber 412 molecular beam epitaxy (MBE) tool designed for growth of Hg1- x Cd x Te compounds. The reactor is equipped with conventional CdTe, Te, and Hg sources for achieving uniform exposure of the wafer during growth. The composition of the Hg1- x Cd x Te compound is controlled in situ by employing a closed-loop spectral ellipsometry technique to achieve a cutoff wavelength ( λ co) of 14 μm at 78 K. We present data on the thickness and composition uniformity of films grown for large-format focal-plane array applications. The composition and thickness nonuniformity are determined to be maps show the spatial distribution of defects generated during the epitaxial growth of the Hg1- x Cd x Te films. Microdefect densities are in the low 103 cm-2 range, and void defects are below 500 cm-2. Dislocation densities less than 5 × 105 cm-2 are routinely achieved for Hg1- x Cd x Te films grown on CZT substrates. HgCdTe 4k × 4k focal-plane arrays with 15 μm pitch for astronomical wide-area infrared imagers have been produced using the recently developed MBE growth process at Teledyne Imaging Sensors.

  18. History of the "Detector Materials Engineering" Crystal Growth Process for Bulk Hg1- x Cd x Te

    Science.gov (United States)

    Higgins, W. M.; Nelson, D. A.; Roy, R. G.; Murosako, R. P.; Lancaster, R. A.; Tower, J.; Norton, P.

    2013-11-01

    This paper reviews the history and technology of a bulk Hg1- x Cd x Te crystal growth process that was developed in the early 1980s at Honeywell Electro-Optics Division (presently BAE Systems, Electronic Solutions). The crystal growth process name, DME, was an acronym for the department name: Detector Materials Engineering. This was an accelerated crucible rotation technique (ACRT) vertical traveling heater method growth process. Crystal growth occurred in the pseudobinary Hg1- x Cd x Te system. ACRT mixing allowed the lower-density, higher- x-value Hg1- x Cd x Te growth nutrient in the upper region of the ampoule to replenish the depleted melt and allowed the growth of constant- x-value, higher-density Hg1- x Cd x Te. The material grown by this research and production growth process yielded single crystals that had improved purity, compositional uniformity, precipitate density, and reproducibility in comparison with solid-state recrystallization and other bulk Hg1- x Cd x Te growth techniques. Radial and longitudinal nonuniformities in x-value for Hg1- x Cd x Te were reduced to DME material had highly desired performance characteristics.

  19. Study of Morphological Defects on Dual-Band HgCdTe on CdZnTe

    Science.gov (United States)

    Reddy, M.; Radford, W. A.; Lofgreen, D. D.; Olsson, K. R.; Peterson, J. M.; Johnson, S. M.

    2014-08-01

    HgCdTe dual-band epitaxial layers on lattice-matched CdZnTe substrates often have morphological defects. These defects, unlike normal void and microvoid defects, do not contain a polycrystalline core and, therefore, do not offer a good contrast for observation using optical and electron microscopes. This paper reports a way of identifying these defects by using a Nomarski optical microscopy image overlay on focused ion beam microscopy images for preparation of thin cross-sectional foils of these defects. Transmission electron microscopy was used to study the defect cross-sections to identify the origin and evolution of the morphological defects and their effect on the epitaxial layer. This paper reports cross-sectional analysis of four morphological defects of different shape and size.

  20. Evaluation of harmful heavy metal (Hg, Pb and Cd reduction using Halomonas elongata and Tetragenococcus halophilusfor protein hydrolysate product

    Directory of Open Access Journals (Sweden)

    Ruttiya Asksonthon

    2016-04-01

    with mercury (Hg, lead (Pb and cadmium (Cd at concentration, 0.5, 1, and 3 mg/L, respectively. Subsequently, the supernatant of each condition was incubated at 48h and taken for heavy metal analysisat96 h. Results: The results showed that higher NaCl content resulted in slower late log and stationary phases, particularly inT. halophilus. This may due to T. halophilus not producing special metabolite such as exopolysaccharide, which was found in H. elongata. Regardless of heavy metal concentration, the results revealed that Cdat 3 mg/kg caused more cell death ofH. Elongate, but not that of T. halophilus. Furthermore, removal of Hg, Pb and Cd was 12.70, 84.78 and 75.83% respectively, by rearing with H. elongata for 48 hand by rearing with T. halophilus for 96 h was 12.68, 91.27 and 95.12%, respectively. Conclusion: H. elongata and T. halophilus prefered SNB containing NaCl concentration between 10-20%. At higher NaCl concentration, 20-25%, the log phase was extended. Both H. elongata and T. halophiluswere able to remove all test heavy metals. However,T. halophilusappearedto have higherPb and Cd removal capability compared with H. elongata. Therefore, using H. elongata andT. Halophilus for fermented tuna viscera is possible.

  1. Dry etched SiO2 Mask for HgCdTe Etching Process

    Science.gov (United States)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  2. Intrinsic Spin Hall Effect Induced by Quantum Phase Transition in HgCdTe Quantum Wells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wen; Chang, Kai; /Beijing, Inst. Semiconductors; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-19

    Spin Hall effect can be induced both by the extrinsic impurity scattering and by the intrinsic spin-orbit coupling in the electronic structure. The HgTe/CdTe quantum well has a quantum phase transition where the electronic structure changes from normal to inverted. We show that the intrinsic spin Hall effect of the conduction band vanishes on the normal side, while it is finite on the inverted side. This difference gives a direct mechanism to experimentally distinguish the intrinsic spin Hall effect from the extrinsic one.

  3. Feasibility of Open Tube Slider Growth of HgCdTe from Te-Rich Solution.

    Science.gov (United States)

    1980-02-01

    od of Equation (26), which assumes CdTe and HgTe molecules are dissolved in Te and that the solution is 3.2 percent less dense than the solid...finished slice is protected with a layer of beeswax and diced to the size of our slider system, either I 1Xlcm 2 or 2X3cm2 . Just before use, the...h time allowed for the solute to dissolve at 770’C produces ent with the annealing studies of Schrnt and Stelzer 1211 on 55 ’- IKIKE TRANSACTIONS ON

  4. Technology for advanced focal plane arrays of HgCdTe and AIGaN

    CERN Document Server

    He, Li; Ni, Guoqiang

    2016-01-01

    This book introduces the basic framework of advanced focal plane technology based on the third-generation infrared focal plane concept. The essential concept, research advances, and future trends in advanced sensor arrays are comprehensively reviewed. Moreover, the book summarizes recent research advances in HgCdTe/AlGaN detectors for the infrared/ultraviolet waveband, with a particular focus on the numerical method of detector design, material epitaxial growth and processing, as well as Complementary Metal-Oxide-Semiconductor Transistor readout circuits. The book offers a unique resource for all graduate students and researchers interested in the technologies of focal plane arrays or electro-optical imaging sensors.

  5. SURFACE RECOMBINATION VELOCITY OF THE HgCdTe SURFACE PASSIVATED WITH SPUTTERING CdTe FILM%CdTe钝化的HgCdTe非平衡载流子表面复合速度的实验研究

    Institute of Scientific and Technical Information of China (English)

    周咏东; 赵军; 龚海梅; 李言谨; 方家熊

    2000-01-01

    利用Ar+束溅射沉积技术在HgCdTe表面实现了低温CdTe介质薄膜的低温生长.在同一HgCdTe晶片表面分别用CdTe介质膜、HgCdTe自身阳极氧化膜进行表面钝化.利用光电导衰退测量技术测量了两种不同表面钝化的薄HgCdTe晶片的非平衡载流子(少数载流子)寿命,并通过光电导衰减信号波形的拟合,得到两种不同表面钝化的HgCdTe表面复合速度.实验结果表明,获得的CdTe/HgCdTe界面质量已超过了成熟的自身阳极氧化膜/HgCdTe界面质量水平.

  6. Electro-Plating and Characterisation of CdTe Thin Films Using CdCl2 as the Cadmium Source

    Directory of Open Access Journals (Sweden)

    Nor A. Abdul-Manaf

    2015-09-01

    Full Text Available Cadmium telluride (CdTe thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2·H2O and tellurium dioxide (TeO2 using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD, Raman spectroscopy, optical profilometry, DC current-voltage (I-V measurements, photoelectrochemical (PEC cell measurement, scanning electron microscopy (SEM, atomic force microscopy (AFM and UV-Vis spectrophotometry. It is observed that the best cathodic potential is 698 mV with respect to standard calomel electrode (SCE in a three electrode system. Structural analysis using XRD shows polycrystalline crystal structure in the as-deposited CdTe thin films and the peaks intensity increase after CdCl2 treatment. PEC cell measurements show the possibility of growing p-, i- and n-type CdTe layers by varying the growth potential during electrodeposition. The electrical resistivity of the as-deposited layers are in the order of 104 Ω·cm. SEM and AFM show that the CdCl2 treated samples are more roughness and have larger grain size when compared to CdTe grown by CdSO4 precursor. Results obtained from the optical absorption reveal that the bandgap of as-deposited CdTe (1.48–1.52 eV reduce to (1.45–1.49 eV after CdCl2 treatment. Full characterisation of this material is providing new information on crucial CdCl2 treatment of CdTe thin films due to its built-in CdCl2 treatment during the material growth. The work is progressing to fabricate solar cells with this material and compare with CdTe thin films grown by conventional sulphate precursors.

  7. Leaching of cadmium and tellurium from cadmium telluride (CdTe) thin-film solar panels under simulated landfill conditions.

    Science.gov (United States)

    Ramos-Ruiz, Adriana; Wilkening, Jean V; Field, James A; Sierra-Alvarez, Reyes

    2017-08-15

    A crushed non-encapsulated CdTe thin-film solar cell was subjected to two standardized batch leaching tests (i.e., Toxicity Characteristic Leaching Procedure (TCLP) and California Waste Extraction Test (WET)) and to a continuous-flow column test to assess cadmium (Cd) and tellurium (Te) dissolution under conditions simulating the acidic- and the methanogenic phases of municipal solid waste landfills. Low levels of Cd and Te were solubilized in both batch leaching tests (<8.2% and <3.6% of added Cd and Te, respectively). On the other hand, over the course of 30days, 73% of the Cd and 21% of the Te were released to the synthetic leachate of a continuous-flow column simulating the acidic landfill phase. The dissolved Cd concentration was 3.24-fold higher than the TCLP limit (1mgL(-1)), and 650-fold higher than the maximum contaminant level established by the US-EPA for this metal in drinking water (0.005mgL(-1)). In contrast, the release of Cd and Te to the effluent of the continuous-flow column simulating the methanogenic phase of a landfill was negligible. The remarkable difference in the leaching behavior of CdTe in the columns is related to different aqueous pH and redox conditions promoted by the microbial communities in the columns, and is in agreement with thermodynamic predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Cadmium triggers Elodea canadensis to change the surrounding water pH and thereby Cd uptake.

    Science.gov (United States)

    Javed, M Tariq; Greger, Maria

    2011-01-01

    This study was aimed to investigate the influence of Elodea canadensis shoots on surrounding water pH in the presence of cadmium and the effect of plant-induced pH on cadmium uptake. The pH change in the surrounding nutrient solution and Cd uptake by Elodea shoots were investigated after cultivation of various plant densities (1, 3, 6 plants per 500 ml) in hydroponics at a starting pH of 4.0 and in the presence of different concentrations of cadmium (0, 0.1, 0.5 microM). Cadmium uptake was also investigated at different constant pH (4.0, 4.5, 5.5 and 6.5). To investigate if the pH change arose from photosynthetic activities, plants were grown under light, darkness or in the presence of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and 0.5 microM cadmium in the solution. Elodea had an ability to increase the surrounding water pH, when the initial pH was low, which resulted in increased accumulation of Cd. The higher the plant density, the more pronounced was the pH change. The pH increase was not due to the photosynthetic activity since the pH rise was more pronounced under darkness and in the presence of DCMU. The pH increase by Elodea was triggered by cadmium.

  9. Comparison of the Schaake and Benson Etches to Delineate Dislocations in HgCdTe Layers

    Science.gov (United States)

    Farrell, S.; Rao, Mulpuri V.; Brill, G.; Chen, Y.; Wijewarnasuriya, P.; Dhar, N.; Benson, J. D.; Harris, K.

    2013-11-01

    The morphology and classification of etch pits in molecular beam epitaxy-grown (211) HgCdTe/CdTe/Si layers were investigated using the Schaake and Benson etch pit density (EPD) etches. The two EPD etches were compared and shown to have a 1:1 correlation in the etch pits that were produced. Close examination of the shape of the etch pits via scanning electron microscopy shows that several distinguishable classifications of etch pits are revealed using both etches. Samples subjected to thermal cycle annealing (TCA) treatment show a nonuniform reduction in etch pit populations according to the classification defined in this study. In particular, a class of etch pits called "fish shaped" are completely absent after TCA and can account for up to one-third of the total reduction in EPD.

  10. Assessment of potential soybean cadmium excluder cultivars at different concentrations of Cd in soils.

    Science.gov (United States)

    Zhi, Yang; He, Kangxin; Sun, Ting; Zhu, Yongqiang; Zhou, Qixing

    2015-09-01

    The selection of cadmium-excluding cultivars has been used to minimize the transfer of cadmium into the human food chain. In this experiment, five Chinese soybean plants were grown in three soils with different concentrations of Cd (0.15, 0.75 and 1.12mg/kg). Variations in uptake, enrichment, and translocation of Cd among these soybean cultivars were studied. The results indicated that the concentration of Cd in seeds that grew at 1.12mg/kg Cd in soils exceeded the permitted maximum levels in soybeans. Therefore, our results indicated that even some soybean cultivars grown on soils with permitted levels of Cd might accumulate higher concentrations of Cd in seeds that are hazardous to human health. The seeds of these five cultivars were further assessed for interactions between Cd and other mineral nutrient elements such as Ca, Cu, Fe, Mg, Mn and Zn. High Cd concentration in soil was found to inhibit the uptake of Mn. Furthermore, Fe and Zn accumulations were found to be enhanced in the seeds of all of the five soybean cultivars in response to high Cd concentration. Cultivar Tiefeng 31 was found to fit the criteria for a Cd-excluding cultivar under different concentrations of Cd in soils.

  11. HgCdTe and silicon detectors and FPAs for remote sensing applications

    Science.gov (United States)

    D'Souza, Arvind I.; Stapelbroek, Maryn G.; Robinson, James E.

    2004-02-01

    Photon detectors and focal plane arrays (FPAs) are fabricated from HgCdTe and silicon in many varieties. With appropriate choices for bandgap in HgCdTe, detector architecture, dopants, and operating temperature, HgCdTe and silicon can cover the spectral range from ultraviolet to the very-long-wavelength infrared (VLWIR), exhibit high internal gain to allow photon counting over this broad spectral range, and can be made in large array formats for imaging. DRS makes HgCdTe and silicon detectors and FPAs with unique architectures for a variety of applications. Detector characteristics of High Density Vertically Integrated Photodiode (HDVIP) HdCdTe detectors as well as Focal Plane Arrays (FPAs) are presented in this paper. MWIR[λc(78 K) = 5 μm] HDVIP detectors RoA performance was measured to within a factor or two or three of theoretical. In addition, 256 x 256 detector arrays were fabricated. Initial measurements had seven out of ten FPAs having operabilities greater than 99.45% with the best 256 x 256 array having only two inoperable pixels. LWIR [λc(78K)~10 μm] 640 X 480 arrays and a variety of single color linear arrays have also been fabricated. In addition, two-color arrays have been fabricated. DRS has explored HgCdTe avalanche photo diodes (APDs) in the λc = 2.2 μm to 5 μm range. The λc = 5 μm APDs have greater than 200 DC gain values at 8 Volts bias. Large-format to 10242 Arsenic-doped (Si:As, λc ~ 28 μm), Blocked-Impurity-Band (BIB) detectors have been developed for a variety of pixel formats and have been optimized for low, moderate, and high infrared backgrounds. Antimony-doped silicon (Si:Sb) BIB arrays having response to wavelengths > 40 μm have also been demonstrated. Avalanche processes in Si:As at low temperatures (~ 8 K) have led to two unique solid-state photon-counting detectors adapted to infrared and visible wavelengths. The infrared device is the solid-state photomultiplier (SSPM). A related device optimized for the visible spectral

  12. Toxicity and Traces of Hg, Pb and Cd in the Hepatopancreas, Gills and Muscles of Perna viridis from Jakarta Bay, Indonesia.

    Science.gov (United States)

    Irnidayanti, Y

    2015-02-01

    Heavy metals contamination on the coast of Jakarta Bay has led to the level of pollution and can cause toxicity to organisms living in the sea, i.e., green mussels. Green mussels have the ability to detoxify metals entering their bodies. Their ability to accumulate metals is higher than other aquatic animals. This is due to their sedentary life which prevents them from avoiding the effects of pollution and their high tolerance to certain metals. The high concentration of metal content would be toxic to the cell because metal ions can act as oxidants and bind to organic and protein molecules. The results of the study showed that traces of heavy metals were detected in the hepatopancreas, gills, muscles and gonads organs of the mussels living in the waters of Muara Angke. Lead (Pb) and cadmium (Cd) were found in all four organs, while mercury (Hg) was not detected in the muscles. Traces of Hg and Cd were not detected in hepatopancreas, gills, muscles and gonads of green mussels in Panimbang, while Pb was detected by 0.00 1 in the male gonads and 0.01 in hepatopancreas. The concentration of Pb in the male gonads are still below the acceptable limit and concentration of Pb in the hepatopancreas is relatively equivalent to the acceptable limit. Metal detection in the organs above shows that the Muara Angke waters tend to be polluted and have an impact on the mussels weight loss as a result of heavy metal toxicity.

  13. Thermal cycling reliability of indirect hybrid HgCdTe infrared detectors

    Science.gov (United States)

    Chen, Xing; He, Kai; Wang, Jian-xin; Zhang, Qin-yao

    2013-09-01

    Thermal cycling reliability is one of the most important issues whether the HgCdTe infrared focal plane array detectors can be applied to both military and civil fields. In this paper, a 3D finite element model for indirect hybrid HgCdTe infrared detectors is established. The thermal stress distribution and thermally induced warpage of the detector assembly as a function of the distance between the detector chip and Si-ROIC, the thickness and the materials properties of electrical lead board in cryogenic temperature are analyzed. The results show that all these parameters have influences on the thermal stress distribution and warpage of the detector assembly, especially the coefficient of thermal expansion(CTE) of electrical lead board. The thermal stress and warpage in the assembly can be avoided or minimized by choosing the appropriate electrical lead board. Additionally, the warpage of some indirect hybrid detectors assembly samples is measured in experiment. The experimental results are in good agreement with the simulation results, which verifies that the results are calculated by finite element method are reasonable.

  14. A New nBn IR Detection Concept Using HgCdTe Material

    Science.gov (United States)

    Gravrand, O.; Boulard, F.; Ferron, A.; Ballet, Ph.; Hassis, W.

    2015-09-01

    This paper presents a new HgCdTe-based heterostructure to perform quantum infrared detection. The structure is based on the unipolar barrier concept, introduced by White in the 1980s for HgCdTe. The driving concept is the use of a large gap barrier layer to impede the flow of majority carriers (electrons on the conduction band in the case of n-type material) while facilitating the transport of minority (photo) carriers (holes on the valence band). The issue encountered here is the formation of a small potential barrier on the valence band, blocking photocarriers and therefore killing the quantum efficiency. The idea is to optimize the structure with an asymmetric barrier: abrupt on the contact side to efficiently block the majority carriers, and gradual on the absorption layer side to plane down the remaining potential barrier for the collected photocarriers. The concept has been studied by finite element modeling simulation and showed promising results. An optimal design has been identified in the middle wave band and molecular beam epitaxy layers have been grown then processed. First experimental characterization of the electro-optical properties of such structures showed promising features: 60% quantum efficiency and low turn-on voltage have been measured on single pixels.

  15. Subcellular localization of several heavy metals of Hg,Cd and Pb in human liver

    Institute of Scientific and Technical Information of China (English)

    CHEN Chunying; ZHANG Peiqun; CHAI Zhifang

    2005-01-01

    Liver, as an important metabolic and detoxicological organ of human body, can be used as a good bioindicator for evaluating body burden of environmental pollutants. Its elemental contents and their chemical forms are closely related to the status of human health and disease. In this paper, the liver samples collected from normal subjects were separated to different subcellular fractions of nuclei, mitochondria, lysosome, microsome and cytosol by differential centrifugation. Then their concentrations of heavy metals of As, Pb, Cd, and Hg were determined by atomic absorption and atomic fluorescent spectroscopy. Our results show no significant difference with literature ones when comparing their gross concentrations. In the case of their subcellular distribution, the Hg concentrations are higher in mitochondrial, microsomal and cytosolic fractions; the Cd concentrations are higher in cytosolic and mitochondrial fractions, while As highest in nuclear fraction. The highest concentration of Pb is found in microsomal fraction with similarity to Fe. Mercury in liver is mainly in the form of inorganic, and methylmercury ranged from 9% to 50% with the average value of 20.9%(13.3%. These results indicate that the cellular distribution and the accumulated target organelles are quite different among these heavy metals, which suggest their various pathways and toxic mechanism in vivo.

  16. Developments in MOVPE HgCdTe arrays for passive and active infrared imaging

    Science.gov (United States)

    Baker, Ian; Maxey, Chris; Hipwood, Les; Weller, Harald; Thorne, Peter

    2012-09-01

    SELEX Galileo Infrared Ltd has developed a range of 3rd Generation infrared detectors based on HgCdTe grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on low cost GaAs substrates. There have been four key development aims: reducing the cost especially for large arrays, extending the wavelength range, improving the operating temperature for lower power, size and weight cameras and increasing the functionality. Despite a 14% lattice mismatch between GaAs and HgCdTe MOVPE arrays show few symptoms of misfit dislocations even in longwave detectors. The key factors in the growth and device technology are described in this paper to explain at a scientific level the radiometric quality of MOVPE arrays. A feature of the past few years has been the increasingly sophisticated products that are emerging thanks to custom designed silicon readout devices. Three devices are described as examples: a multifunctional device that can operate as an active or passive imager with built-in range finder, a 3-side buttable megapixel array and an ultra-low noise device designed for scientific applications.

  17. Spatial distribution of dissolved Pb,Hg,Cd,Cu and As in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25.2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas.Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals,followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data,average concentrations of dissolved heavy metals appear to decline in recent years.

  18. Numerical Device Modeling, Analysis, and Optimization of Extended-SWIR HgCdTe Infrared Detectors

    Science.gov (United States)

    Schuster, J.; DeWames, R. E.; DeCuir, E. A.; Bellotti, E.; Dhar, N.; Wijewarnasuriya, P. S.

    2016-09-01

    Imaging in the extended short-wavelength infrared (eSWIR) spectral band (1.7-3.0 μm) for astronomy applications is an area of significant interest. However, these applications require infrared detectors with extremely low dark current (less than 0.01 electrons per pixel per second for certain applications). In these detectors, sources of dark current that may limit the overall system performance are fundamental and/or defect-related mechanisms. Non-optimized growth/device processing may present material point defects within the HgCdTe bandgap leading to Shockley-Read-Hall dominated dark current. While realizing contributions to the dark current from only fundamental mechanisms should be the goal for attaining optimal device performance, it may not be readily feasible with current technology and/or resources. In this regard, the U.S. Army Research Laboratory performed physics-based, two- and three-dimensional numerical modeling of HgCdTe photovoltaic infrared detectors designed for operation in the eSWIR spectral band. The underlying impetus for this capability and study originates with a desire to reach fundamental performance limits via intelligent device design.

  19. Recovery of cadmium by high-temperature vaccum evaporation from Ni-Cd batteries

    Institute of Scientific and Technical Information of China (English)

    朱建新; 李金惠; 聂永丰; 于波

    2003-01-01

    High-temperature vaccum evaporation is a recycling technology that includes a selective material recovering process. The fundamental research on a process of disassembling and recovering selected materials from Ni-Cd batteries was conducted using self-designed experimental apparatus. An effective recycling technology based on the evaporation phenomenon of batteries and the elements of cadmium under the laboratory condition was studied. The results show that: (1)Ni/Cd can be effectively recovered by vacuum distillation at appropriate temperature, pressure and time, and high purity cadmium (>99%) can be obtained through the process; (2)the effective distillatory temperature should be at the range of 573-1173K; (3)the higher the evaporation temperature, the lower the purity of cadmium in condensate metal

  20. A density functional theory study of Raman modes of cadmium hexathiohypodiphosphate (CdPS3

    Directory of Open Access Journals (Sweden)

    Shakoor Abdul

    2015-06-01

    Full Text Available Raman scattering investigations based on density functional theory (DFT calculations were performed to explore the vibrational modes of a cadmium hexathiohypodiphosphate CdPS3 single crystal. The calculations were performed to obtain the Raman spectra for the cadmium hexathiohypodiphosphate atoms to study the size dependence. Several vibrational modes indicating stretching and bending features related to Cd, S and P atoms were observed. Modifications of the frequency and intensity of different Raman modes with an increase in the number of atoms in CdPS3 were discussed in detail. Hydrogen atoms were added in order to make the closed shell configuration and saturate the CdPS3 as per the requisite for calculating the Raman spectra. This produced some additional modes of vibration related to hydrogen atoms. Band gap and formation energy were also calculated. The results generated are found to be in close agreement with the experimental values.

  1. Heavy metal levels (Pb, Cd, Cr and Hg) in the adult general population near an urban solid waste incinerator

    Energy Technology Data Exchange (ETDEWEB)

    Zubero, Miren Begona, E-mail: txitea@gmail.com [Research Unit, Cruces Hospital, Barakaldo, Bizkaia (Spain); Department of Preventative Medicine and Public Health, University of the Basque Country, Leioa, Bizkaia (Spain); Aurrekoetxea, Juan Jose, E-mail: jaurrekoetxea@ej-gv.es [Public Health Department, Dept. of Health, Basque Government, Gipuzkoa (Spain); Epidemiolgy and Public Health CIBER (CIBERESP) (Spain); Ibarluzea, Jesus Maria, E-mail: mambien3-san@ej-gv.es [Public Health Department, Dept. of Health, Basque Government, Gipuzkoa (Spain); Epidemiolgy and Public Health CIBER (CIBERESP) (Spain); Arenaza, Maria Jesus, E-mail: osalanrlhba@ej-gv.es [Basque Institute for Occupational Health and Safety, Barakaldo, Bizkaia (Spain); Rodriguez, Carlos, E-mail: carlos.rodriguez-andres@ehu.es [Department of Preventative Medicine and Public Health, University of the Basque Country, Leioa, Bizkaia (Spain); Saenz, Jose Ramon, E-mail: jrsaenz@chdo.osakidetza.net [Department of Preventative Medicine and Public Health, University of the Basque Country, Leioa, Bizkaia (Spain)

    2010-09-15

    In 2005 an urban solid waste incinerator (SWI) was commissioned in Bilbao (Basque Country, Spain). Serum and urine samples were collected from 95 and 107 volunteers in 2006 and 2008 respectively, of which 62 were repeats from the same individuals. Blood lead levels (BPb) were determined, as were the concentrations of cadmium (Cd), chromium (Cr) and mercury (Hg) in urine (UCd, UCr and UHg). The town of Alonsotegi and a borough of Bilbao (Altamira, Rekalde) were considered to be close, less than 2 km from the plant, and correspond to an urban environment with high traffic density. The areas of reference were a borough of Bilbao (Santutxu-Zurbaran), 5 km from the plant, also in an urban area with high traffic density, and a small town with little industrial activity and low traffic density (Balmaseda) 20 km from the plant; neither of these is downwind from the site with respect to prevailing winds. There was a significant correlation for BPb, r = 0.63 (p < 0.001), between the two surveys. However, there was no linear correlation for the other three metals (UCd, UCr and UHg), between the two sampling periods (p > 0.05). Multiple linear regression models did not show increases over time of the levels of BPb, UCd, UCr and UHg in the areas close to the SWI compared to those of areas located further away, after adjusting for confounding variables. These results reinforce the hypothesis that populations near modern plants for solid waste incineration do not manifest increased levels of heavy metals.

  2. Minority carrier lifetime in iodine-doped molecular beam epitaxy-grown HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Madni, I.; Umana-Membreno, G. A.; Lei, W.; Gu, R.; Antoszewski, J.; Faraone, L. [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Crawley, Western Australia 6009 (Australia)

    2015-11-02

    The minority carrier lifetime in molecular beam epitaxy grown layers of iodine-doped Hg{sub 1−x}Cd{sub x}Te (x ∼ 0.3) on CdZnTe substrates has been studied. The samples demonstrated extrinsic donor behavior for carrier concentrations in the range from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3} without any post-growth annealing. At a temperature of 77 K, the electron mobility was found to vary from 10{sup 4} cm{sup 2}/V s to 7 × 10{sup 3} cm{sup 2}/V s and minority carrier lifetime from 1.6 μs to 790 ns, respectively, as the carrier concentration was increased from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3}. The diffusion of iodine is much lower than that of indium and hence a better alternative in heterostructures such as nBn devices. The influence of carrier concentration and temperature on the minority carrier lifetime was studied in order to characterize the carrier recombination mechanisms. Measured lifetimes were also analyzed and compared with the theoretical models of the various recombination processes occurring in these materials, indicating that Auger-1 recombination was predominant at higher doping levels. An increase in deep-level generation-recombination centers was observed with increasing doping level, which suggests that the increase in deep-level trap density is associated with the incorporation of higher concentrations of iodine into the HgCdTe.

  3. Concentration of Cd, Pb, Hg, and Se in Different Parts of Human Breast Cancer Tissues

    Directory of Open Access Journals (Sweden)

    Mehrnoosh Mohammadi

    2014-01-01

    Full Text Available Breast cancer is the major cause of cancer morbidity and mortality between women in the world. Metals involved in environmental toxicology are closely related to tumor growth and cancer. On the other hand, some metals such as selenium have anticarcinogenic properties. The aim of this study is to determine the concentration of cadmium, lead, mercury, and selenium in separated parts of tegmen, tumor, tumor adiposity, and tegmen adiposity of 14 breast cancer tissues which have been analyzed by graphite furnace atomic absorption (AA-670 and ICP-OES (ULTIMA 2CE. Our results show that Se and Hg have maximum and minimum concentration, respectively. Statistical analysis reveals no significant differences between metal accumulations in different parts of cancer tissues (P>0.05 and this observation might be due to the close relation of separated parts of fatty breast organ. Thus, we could conclude that a high level of these heavy metals is accumulated in Iranian cancerous breasts and their presence can be one of the reasons of cancer appearance.

  4. Determination of As, Cd, Cu, Hg and Pb in biological samples by modern electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Sardans, Jordi, E-mail: j.sardans@creaf.uab.ca [Ecophysiological and Global Change Unit CSIC-CREAF, Edifici C, Universitat Autonoma de Barcelona, Bellaterra 08193, Barcelona (Spain); Montes, Fernando [Departamento de Ciencias Analiticas, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), C/ Senda del Rey 9. 28040 Madrid (Spain); Penuelas, Josep [Ecophysiological and Global Change Unit CSIC-CREAF, Edifici C, Universitat Autonoma de Barcelona, Bellaterra 08193, Barcelona (Spain)

    2010-02-15

    Pollution from heavy metals has increased in recent decades and has become an important concern for environmental agencies. Arsenic, cadmium, copper, mercury and lead are among the trace elements that have the greatest impact and carry the highest risk to human health. Electrothermal atomic absorption spectrometry (ETAAS) has long been used for trace element analyses and over the past few years, the main constraints of atomic absorption spectrometry (AAS) methods, namely matrix interferences that provoked high background absorption and interferences, have been reduced. The use of new, more efficient modifiers and in situ trapping methods for stabilization and pre-concentration of these analytes, progress in control of atomization temperatures, new designs of atomizers and advances in methods to correct background spectral interferences have permitted an improvement in sensitivity, an increase in detection power, reduction in sample manipulation, and increase in the reproducibility of the results. These advances have enhanced the utility of Electrothermal atomic absorption spectrometry (ETAAS) for trace element determination at mug L{sup -1} levels, especially in difficult matrices, giving rise to greater reproducibility, lower economic cost and ease of sample pre-treatment compared to other methods. Moreover, the recent introduction of high resolution continuum source Electrothermal atomic absorption spectrometry (HR-CS-ETAAS) has facilitated direct solid sampling, reducing background noise and opening the possibility of achieving even more rapid quantitation of some elements. The incorporation of flow injection analysis (FIA) systems for automation of sample pre-treatment, as well as chemical vapor generation renders (ETAAS) into a feasible option for detection of As and Hg in environmental and food control studies wherein large numbers of samples can be rapidly analyzed. A relatively inexpensive approach with low sample consumption provide additional advantages

  5. Differential influences of Cu and Zn chronic exposure on Cd and Hg bioaccumulation in an estuarine oyster.

    Science.gov (United States)

    Liu, Fengjie; Wang, Wen-Xiong

    2014-03-01

    In this study, the effects of Cu and Zn exposure, alone and in combination, on the bioaccumulation of Cd and Hg were investigated in an estuarine oyster Crassostrea hongkongensis under different salinity gradients. We showed that Zn, but not Cu, exposure significantly enhanced the Cd bioaccumulation. In contrast, both Cu and Zn exposure significantly enhanced the Hg bioaccumulation. Combined exposure and salinity did not affect the metal interactions in oysters. The increased tissue concentrations of Cd or Hg were associated with their increased storage in inducible metal-binding ligands (e.g. metallothionein-like proteins, MTLP) by Cu/Zn exposure. The differential roles of Cu and Zn exposure in Cd and Hg bioaccumulation resulted from their contrasting ligand induction and affinities. Analysis of field collected oysters indicated that Cu/Zn exposure was a significant contributor to tissue concentrations of Cd, Cu and Hg. Overall, biochemical/physiological changes of the animals chronically exposed to metal stressors played a key role in affecting tissue concentrations of other metals. One metal's ability to enhance the bioaccumulation of other metals depended upon the relative affinities of the metals for MTLP.

  6. Evolution of oxygenated cadmium sulfide (CdS:O) during high-temperature CdTe solar cell fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Meysing, Daniel M.; Reese, Matthew O.; Warren, Charles W.; Abbas, Ali; Burst, James M.; Mahabaduge, Hasitha P.; Metzger, Wyatt K.; Walls, John M.; Lonergan, Mark C.; Barnes, Teresa M.; Wolden, Colin A.

    2016-12-01

    Oxygenated cadmium sulfide (CdS:O) produced by reactive sputtering has emerged as a promising alternative to conventional CdS for use as the n-type window layer in CdTe solar cells. Here, complementary techniques are used to expose the window layer (CdS or CdS:O) in completed superstrate devices and combined with a suite of materials characterization to elucidate its evolution during high temperature device processing. During device fabrication amorphous CdS:O undergoes significant interdiffusion with CdTe and recrystallization, forming CdS1-yTey nanocrystals whose Te fraction approaches solubility limits. Significant oxygen remains after processing, concentrated in sulfate clusters dispersed among the CdS1-yTey alloy phase, accounting for ~30% of the post-processed window layer based on cross-sectional microscopy. Interdiffusion and recrystallization are observed in devices with un-oxygenated CdS, but to a much lesser extent. Etching experiments suggest that the CdS thickness is minimally changed during processing, but the CdS:O window layer is reduced from 100 nm to 60-80 nm, which is confirmed by microscopy. Alloying reduces the band gap of the CdS:O window layer to 2.15 eV, but reductions in thickness and areal density improve its transmission spectrum, which is well matched to device quantum efficiency. The changes to the window layer in the reactive environments of device fabrication are profoundly different than what occurs by thermal annealing in an inert environment, which produced films with a band gap of 2.4 eV for both CdS and CdS:O. These results illustrate for the first time the significant changes that occur to the window layer during processing that are critical to the performance of CdTe solar cells.

  7. Spatial noise limited NETD performance of a HgCdTe hybrid focal plane array

    Science.gov (United States)

    Gopal, Vishnu

    1996-04-01

    This paper presents a model for theoretically estimating the residual spatial noise in a direct injection readout hybrid focal plane array (FPA) consisting of photovoltaic detectors. The procedure consists of computing the response of the pixels after taking into account the nonlinearity induced by the transfer function in the hybrid configuration and the estimated r.m.s. response nonuniformity from the known input parameters of the detector and readout arrays. A linear two point nonuniformity compensation algorithm is applied to the computed pixel responses to calculate the residual spatial noise. Signal-to-spatial noise ratio is then used to estimate the spatial noise limited NETD performance of MWIR and LWIR Hg 1- x Cd x Te hybrid FPAs.

  8. (55)Fe X-ray Response of HgCdTe NIR Detector Arrays

    Science.gov (United States)

    Fox, Ori; Rauscher, Bernard J.

    2008-01-01

    Conversion gain is a fundamental parameter in detector characteristics that is used to measure many identifying detector properties, including read noise, dark current, and quantum efficiency (QE). Charge coupling effects, such as inter-pixel capacitance, attenuate photon shot noise and result in an overestimation of of conversion gain when implementing the photon transfer technique. The (55)Fe X-ray technique is a direct and simple method by which to measure the conversion gain by comparing the observed instrumental counts (ADU) to the known charge (e-) liberated by a single X-ray photon. Here we present the calibrated pair production energy for 1.7 micron HgCdTe infrared detectors.

  9. Quantitative damage depth profiles in arsenic implanted HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Lobre, C., E-mail: clement.lobre@cea.fr [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jalabert, D. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Vickridge, I.; Briand, E.; Benzeggouta, D. [Institut des NanoSciences de Paris, UMR 7588 du CNRS, Universite de Pierre et Marie Curie, Paris (France); Mollard, L. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jouneau, P.H. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Ballet, P. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)

    2013-10-15

    Rutherford backscattering experiments under channeling conditions (RBS-c) have been carried out on Hg{sub 0.77}Cd{sub 0.23}Te (MCT) layers implanted with arsenic. Accurate damage profiles have been extracted through a simple formalism for implanted and annealed layers. Quantitative damage profiles are correlated with structural defects observed by bright-field scanning transmission electron microscopy (BF-STEM) and chemical composition measured by secondary ion mass spectrometry (SIMS). Evolution of damage for increasing ion implantation fluence has been investigated by these three complementary techniques. Evidence is found of irradiation induced annealing during implantation. A fast damage recovery has been observed for post-implantation thermal anneals. In the case of an implanted layer annealed during 1 h, the damage profile, associated with arsenic concentration measurements, indicates the presence of complexes involving arsenic.

  10. HgCdTe Avalanche Photodiode Detectors for Airborne and Spaceborne Lidar at Infrared Wavelengths

    Science.gov (United States)

    Sun, Xiaoli; Abshire, James B.; Beck, Jeffrey D.; Mitra, Pradip; Reiff, Kirk; Yang, Guangning

    2017-01-01

    We report results from characterizing the HgCdTe avalanche photodiode (APD) sensorchip assemblies (SCA) developed for lidar at infrared wavelength using the high density vertically integrated photodiodes (HDVIP) technique. These devices demonstrated high quantum efficiency, typically greater than 90 between 0.8 micrometers and the cut-off wavelength, greater than 600 APD gain, near unity excess noise factor, 6-10 MHz electrical bandwidth and less than 0.5 fW/Hz(exp.1/2) noise equivalent power (NEP). The detectors provide linear analog output with a dynamic range of 2-3 orders of magnitude at a fixed APD gain without averaging, and over 5 orders of magnitude by adjusting the APD and preamplifier gain settings. They have been successfully used in airborne CO2 and CH4 integrated path differential absorption (IPDA) lidar as a precursor for space lidar applications.

  11. Characterization of the Microstructure of HgCdTe with p-Type Doping

    Science.gov (United States)

    Lobre, C.; Jouneau, P.-H.; Mollard, L.; Ballet, P.

    2014-08-01

    Nitrogen, phosphorus, arsenic, and antimony ions were implanted in Hg0.3Cd0.7Te (MCT) layers under the same implantation conditions. An identical annealing process was then applied to these layers to eradicate implantation damage and to activate the impurities. Implantation damage was investigated by direct visualization, by use of bright-field scanning transmission electron microscopy (BF-STEM). Secondary-ion mass spectrometry was used to investigate impurity diffusion on annealing. The combination of these two techniques revealed the significant effect of structural implantation damage on the diffusion process. Annealed layers were then investigated by high-resolution STEM imaging and energy-dispersive x-ray spectroscopy in STEM (STEM-EDX). This approach enables direct visualization and, therefore, further description of arsenic and antimony-rich nanocrystals.

  12. Volatile (As and Hg) and non-volatile (Pb and Cd) toxic heavy metals analysis in rhizome of Zingiber officinale collected from different locations of North Western Himalayas by Atomic Absorption Spectroscopy.

    Science.gov (United States)

    Gupta, S; Pandotra, P; Gupta, A P; Dhar, J K; Sharma, G; Ram, G; Husain, M K; Bedi, Y S

    2010-10-01

    Ginger is an important ingredient of spice and herbals. The monitoring of toxic heavy metals in the rhizome of ginger is important for protecting public health against the hazards of metal toxicity. The concentration of volatile and non-volatile metals (As, Hg, Pb and Cd), in the soil and rhizome of Zingiber officinale were analyzed using AAS. Soil analysis profile showed uniformity in the metal contents, in active root zone and subsoil, except mercury, which was present in higher quantity in one, out of the four sectors, of the field. The infield metal content in the soil in increasing order was, cadmium < arsenic < lead < mercury. In ginger rhizome the volatile toxic heavy metals arsenic (As) and mercury (Hg) varied from not detected to 0.13 μg/g and 0.01 to 0.42 μg/g, respectively. The non-volatile metals lead (Pb) and cadmium (Cd) ranged from 0.06 to 0.64 μg/g and 0.002 to 0.03 μg/g, respectively(.) The results illustrated the findings that soil is the major but not the only source of metal accumulation in the plants. In our study, the volatile metal content (As, Hg) was found more in rhizomes collected from Himachal Pradesh while the non-volatile metals were predominant in samples from Uttarakhand.

  13. Numerical modeling of HgCdTe solidification: effects of phase diagram double-diffusion convection and microgravity level

    Science.gov (United States)

    Bune, Andris V.; Gillies, Donald C.; Lehoczky, Sandor L.

    1997-07-01

    A numerical model of HgCdTe solidification was implemented using finite the element code FIDAP. Model verification was done using both experimental data and numerical test problems. The model was used to eluate possible effects of double- diffusion convection in molten material, and microgravity level on concentration distribution in the solidified HgCdTe. Particular attention was paid to incorporation of HgCdTe phase diagram. It was found, that below a critical microgravity amplitude, the maximum convective velocity in the melt appears virtually independent on the microgravity vector orientation. Good agreement between predicted interface shape and an interface obtained experimentally by quenching was achieved. The results of numerical modeling are presented in the form of video film.

  14. Analysis of IMP-grown Cd sub x Hg sub 1-x Te using helium ion RBS

    Energy Technology Data Exchange (ETDEWEB)

    Avery, A.J.; Diskett, D.J. (Royal Military Coll. of Science, Shrivenham, Swindon (United Kingdom)); Gough, J.S.; Young, M.L. (Royal Signals and Radar Establishment, Malvern (United Kingdom))

    1992-02-01

    Epitaxial layers of Cd{sub x}Hg{sub 1-x}Te may be grown by the IMP (interdiffused multilayer process) technique in which alternate layers of CdTe and HgTe are deposited by metalorganic vapour phase epitaxy and interdiffused at the growth temperature. The infrared optical properties of the layers are critically dependent upon the value of x which may be tailored by controlling the relative thickness of the CdTe and HgTe sublayers. This paper describes the application of helium ion RBS to the study of the completeness of interdiffusion between sublayers and the application of channelling to the study of their crystalline quality. (orig.).

  15. Magnum(R) NiCd advanced nickel-cadmium battery cells

    Science.gov (United States)

    Scoles, Darren

    1995-01-01

    The Power Systems Department of Eagle-Picher Industries, Inc., located in Colorado Springs, Colorado, had developed a long-life advanced Nickel-Cadmium battery cell for aerospace applications. This battery cell, known as the MAGNUM NiCd cell, offers significant life expectancy increase over traditional NiCd battery cells. In addition, it offers significant cost reduction from the Super NiCd battery cell (developed by Hughes Aircraft Company and manufactured by the Power Systems Department of Eagle-Picher Industries, Inc.).

  16. Quantum chemistry insight into Mg-substitution in chlorophyll by toxic heavy metals: Cd, Hg and Pb

    Science.gov (United States)

    Bechaieb, Rim; Ben Akacha, Azaiez; Gérard, Hélène

    2016-10-01

    In this paper, we examined the structural, electronic and energetic data associated to the Mg-substitution in chlorophyll by three major toxic pollutants: Cd2+, Hg2+ and Pb2+. We evidenced a highly versatile bonding of the cations with the pheophytin ligand, with a strong out-of-plane distortion for Hg and Pb. The binding energies ranged from slightly stronger than Mg2+ in the case of Hg2+ to much smaller for Pb2+. Nevertheless, our various approaches of free cations solvation allowed us to evidence that Mg-substitution should be possible for all title elements.

  17. Thermoelectric properties of MBE-grown HgCdTe-based superlattices from 100K to 300K

    Science.gov (United States)

    Zhang, Kejia; Yadav, Abhishek; Shao, Lei; Bommena, Ramana; Zhao, Jun; Velicu, Silviu; Pipe, Kevin P.

    2016-07-01

    We report on the thermoelectric properties of long-period HgCdTe superlattices (MCT SLs) from cryogenic temperature to room temperature. We find that the thermal conductivity is lower than the alloy value especially at low temperatures, the electrical conductivity is similar to that of alloy films, and the Seebeck coefficient is comparable to other SLs. Calculations based on Rytov's elastic model show that the phonon group velocity is reduced due to folding by more than a factor of two relative to its value in bulk CdTe or HgTe. Thermal conductivity is found to be relatively constant over a wide range of temperatures.

  18. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jian, E-mail: zhaojian0209@aliyun.com [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); He, Man-Chao [State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China)

    2014-10-30

    Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

  19. First principles study on electronic structure and elastic properties of LaCd and LaHg

    Energy Technology Data Exchange (ETDEWEB)

    Devi, Hansa, E-mail: gita-pagare@yahoo.co.in, E-mail: gita-pagare@yahoo.co.in; Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in, E-mail: gita-pagare@yahoo.co.in; Chouhan, S. S., E-mail: gita-pagare@yahoo.co.in, E-mail: gita-pagare@yahoo.co.in [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal-462002 (India); Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal-462026 (India)

    2014-04-24

    Full -potential linearized augmented plane wave method (FP- LAPW) has been used for the comparative study of electronic structure and elastic properties of CsCl-type LaCd and LaHg intermetallic compounds using generalized gradient approximation (GGA). The density of states at the Fermi Level, N (E{sub F}), is found to be 0.06 and 3.03 states/eV for LaCd and LaHg respectively. We report elastic constants for these compounds for the first time. The ductility/brittleness of these compounds has been analyzed using Pugh rule and Cauchy’s pressure.

  20. Competitive adsorption of Cd, Cu, Hg and Pb by agricultural soils of the Changjiang and Zhujiang deltas in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas,China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concentration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased.The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils.

  1. Ultra-Low Dark Current HgCdTe Detector in SWIR for Space Applications

    Science.gov (United States)

    Cervera, C.; Boulade, O.; Gravrand, O.; Lobre, C.; Guellec, F.; Sanson, E.; Ballet, P.; Santailler, J. L.; Moreau, V.; Zanatta, J. P.; Fieque, B.; Castelein, P.

    2016-09-01

    This paper presents recent developments at Commissariat à l'Energie atomique, Laboratoire d'Electronique et de Technologie de l'Information infrared laboratory on processing and characterization of p-on-n HgCdTe (MCT) planar infrared focal plane arrays (FPAs) in short-wave infrared (SWIR) spectral band for the astrophysics applications. These FPAs have been grown using both liquid phase epitaxy and molecular beam epitaxy on a lattice-matched CdZnTe substrate. This technology exhibits lower dark current and lower series resistance in comparison with n-on-p vacancy-doped architecture and is well adapted for low flux detection or high operating temperature. This architecture has been evaluated for space applications in long-wave infrared and very-long-wave infrared spectral bands with cut-off wavelengths from 10 μm up to 17 μm at 78 K and is now evaluated for the SWIR range. The metallurgical nature of the absorbing layer is also examined and both molecular beam epitaxy and liquid phase epitaxy have been investigated. Electro-optical characterizations have been performed on individual photodiodes from test arrays, whereas dark current investigation has been performed with a fully functional readout integrated circuit dedicated to low flux operations.

  2. 硫、氮双齿配体与Cd(Ⅱ)和Hg(Ⅱ)配合物的合成与表征%Synthesis of Complexes of Bidentate Ligands with Cd(Ⅱ) and Hg(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    刘晓岚; 刘永红; 袁冬梅; 景淆壁; 石尧成

    2005-01-01

    以HMFC[(反)-肉桂酰基二茂铁缩(S)-甲基二硫代碳酰腙]与HBFC[(反)-肉桂酰基二茂铁缩(S)-苄基二硫代碳酰腙]两种Schiff碱分别与醋酸镉[Cd(OAc)2·2H2O]、醋酸汞[Hg(OAc)2]反应,合成了6个未见文献报道的配合物Cd(MFC)2·H2O,Cd(MFC)OAc,Cd(BFC)2,Hg(MFC)2,Hg(MFC)OAc,Hg(BFC)2,考察了其物理性质,并利用元素分析、IR,1HNMR及摩尔电导表征了其组成、可能结构,推断了配位过程.结果表明:这两种Schiff碱都是反式双齿配体,经烯硫醇化并失去质子后,以负硫离子与过渡金属离子形成共价键,氮原子与中心金属离子形成配位键.

  3. Determination of As, Cd, Pb, and Hg in urine using inductively coupled plasma mass spectrometry with the direct injection high efficiency nebulizer

    Science.gov (United States)

    Minnich, Michael G.; Miller, Derek C.; Parsons, Patrick J.

    2008-03-01

    The application of the large-bore direct injection high efficiency nebulizer (LB-DIHEN) for the determination of arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in urine by inductively coupled plasma mass spectrometry (ICP-MS) is described. The LB-DIHEN is compared with the standard method using a concentric pneumatic nebulizer and cyclonic spray chamber. In addition to the toxicological significance of As, Cd, Pb, and Hg, these elements represent a cross-section of analytical issues including spectral interferences (e.g., 40Ar 35Cl + on 75As + and 98Mo 16O + on 114Cd +) and memory effects (Hg). In this study, the low sample consumption of the LB-DIHEN is used to reduce the volume of urine needed for analysis, and to reduce the volume of final diluted sample required for analysis. Eliminating the spray chamber and reducing the dead volume of the nebulizer reduces memory effects, especially for analytes such as Hg. The Dynamic Reaction Cell (DRC) is used in this study to attenuate the background level of ArCl + in spite of the increase in the solvent load and, in turn, the urine matrix (chloride) delivered to the plasma by the LB-DIHEN. This is the first report on coupling the LB-DIHEN to a standard autosampler for unattended sample analysis. The robustness of direct injection nebulization for routine analysis and the issues associated with automation of the sample introduction process are discussed. Although the figures of merit (sensitivity, limit of detection, and precision) determined for both nebulizers are slightly poorer for the LB-DIHEN than for the concentric pneumatic nebulizer, there is not a clinically significant difference between the results for both sample introduction systems. The accuracy of results is assessed using archived urine materials that are circulated by several different proficiency testing (PT) programs and external quality assessment schemes (EQAS). Results obtained using the LB-DIHEN were within the acceptable range

  4. Growth and characterization of Hg1–CdTe epitaxial films by isothermal vapour phase epitaxy (ISOVPE)

    Indian Academy of Sciences (India)

    Manju Malhotra; Madhukar Gautam; J K Radhakrishnan; Vinod Kapoor; Sudeep Verma; Upendra Kumar; Anand Kumar; Garima Gupta; Anshu Goyal; S Sitharaman

    2005-04-01

    Growth of Hg1–CdTe epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have been successfully solved. The epitaxial films have been electrically characterized by using the Hall effect and capacitance–voltage (–) measurements.

  5. Cd-Resistant Strains of B. cereus S5 with Endurance Capacity and Their Capacities for Cadmium Removal from Cadmium-Polluted Water.

    Science.gov (United States)

    Wu, Huiqing; Wu, Qingping; Wu, Guojie; Gu, Qihui; Wei, Linting

    2016-01-01

    The goal of this study was to identify Cd-resistant bacterial strains with endurance capacity and to evaluate their ability to remove cadmium ions from cadmium-polluted water. The Bacillus cereusS5 strain identified in this study had the closest genetic relationship with B. cereus sp. Cp1 and performed well in the removal of Cd2+ions from solution. The results showed that both the live and dead biomasses of the Cd2+-tolerant B. cereus S5 strain could absorb Cd2+ ions in solution but that the live biomass of the B. cereus S5 strain outperformed the dead biomass at lower Cd2+concentrations. An analysis of the cadmium tolerance genes of B. cereus S5 identified ATPase genes that were associated with cadmium tolerance and involved in the ATP pumping mechanism. The FTIR spectra revealed the presence of amino, carboxyl and hydroxyl groups on the pristine biomass and indicated that the cadmium ion removal ability was related to the structure of the strain. The maximum absorption capacity of the B. cereus S5 strain in viable spore biomass was 70.16 mg/g (dry weight) based on a pseudo-second-order kinetic model fit to the experimental data. The Langmuir and Langmuir-Freundlich isotherm adsorption models fit the cadmium ion adsorption data well, and the kinetic curves indicated that the adsorption rate was second-order. For Cd2+ concentrations (mg/L) of 1-109 mg/L, good removal efficiency (>80%) was achieved using approximately 3.48-10.3 g/L of active spore biomass of the B. cereus S5 strain. A cadmium-tolerant bacteria-activated carbon-immobilized column could be used for a longer duration and exhibited greater treatment efficacy than the control column in the treatment of cadmium-polluted water. In addition, a toxicity assessment using mice demonstrated that the biomass of the B. cereus S5 strain and its fermentation products were non-toxic. Thus, the isolated B. cereus S5 strain can be considered an alternative biological adsorbent for use in emergency responses to severe

  6. Adsorbent-adsorbate interactions in the adsorption of Cd(II) and Hg(II) on ozonized activated carbons.

    Science.gov (United States)

    Sánchez-Polo, M; Rivera-Utrilla, J

    2002-09-01

    The present work investigated the effect of surface oxygenated groups on the adsorption of Cd(II) and Hg(II) by activated carbon. A study was undertaken to determine the adsorption isotherms and the influence of the pH on the adsorption of each metallic ion by a series of ozonized activated carbons. In the case of Cd(II), the adsorption capacity and the affinity of the adsorbent augmented with the increase in acid-oxygenated groups on the activated carbon surface. These results imply that electrostatic-type interactions predominate in this adsorption process. The adsorption observed at solution pH values below the pH(PZC) of the carbon indicates that other forces also participate in this process. Ionic exchange between -C pi-H3O+ interaction protons and Cd(II) ions would account for these findings. In the case of Hg(II), the adsorption diminished with an increase in the degree of oxidation of the activated carbon. The presence of electron-withdrawing groups on oxidized carbons decreases the electronic density of their surface, producing a reduction in the adsorbent-adsorbate dispersion interactions and in their reductive capacity, thus decreasing the adsorption of Hg(II) on the activated carbon. At pH values above 3, the pH had no influence on the adsorption of Hg(II) by the activated carbon, confirming that electrostatic interactions do not have a determinant influence on Hg(II) adsorption.

  7. Toxic harm of Hg2+、Cd2+ and their combined stress on Elodea nuttallii%Hg2+、Cd2+及其复合胁迫对伊乐藻的毒害

    Institute of Scientific and Technical Information of China (English)

    吴振斌; 马剑敏; 赵强; 贺锋; 成水平

    2005-01-01

    利用水生微宇宙系统研究了不同浓度的Hg2+、Cd2+单一及复合处理对伊乐藻可溶性蛋白质浓度、叶绿素含量、叶绿素a/b比值,以及生产力和呼吸作用的影响.可溶性蛋白质和叶绿素含量在低浓度胁迫时(Hg2+≤2.5μmol/L,Cd2+≤10μmol/L,Hg2+ +Cd2+≤1.25μmol/L Hg2++5μmol/L Cd2+)略有升高,之后随胁迫的增强而持续下降,两者呈负相关;叶绿素a/b比值、净生产力、呼吸强度随离子浓度增加不断下降,除呼吸强度外,两者也呈负相关.Hg2+对伊乐藻的毒性是Cd2+的4倍左右(以摩尔浓度计).两者共同作用时,对可溶性蛋白和叶绿素含量以及净生产力的影响有协同效应,对呼吸作用的影响有相加效应.

  8. [The role of Cd-binding proteins and phytochelatins in the formation of cadmium resistance in Nicotiana plumbaginifolia cell lines].

    Science.gov (United States)

    Fenik, S I; Solodushko, V G; Kaliniak, T B; Blium, Ia B

    2007-01-01

    Nicotiana plumbaginifolia callus lines with the equal resistance to cadmium have been produced under different selective conditions--either without inhibition of the phytochelatin synthesis (line Cd-R) or in the presence of the inhibitor butionine sulfoximine (line Cd-Ri). The level of phytochelatin synthesis in the line Cd-R five-fold exceeded the control value and in the line Cd-Ri it was twice as much as in the control. It was shown that in the control line mainly three cadmium-binding proteins are expressed of the molecular weihgts 41, 34 and 19 kD. The common feature of the both resistant lines is the expression of the cadmium-binding proteins of 40, 37 and 19 kD. The resistant lines differ with respect to the synthesis of relatively low-molecular cadmium-binding proteins. The proteins of the molecular weights 12.5, 11.5 and 9 kD are expressed in the line Cd-R, while the proteins of 13 and 10 kD are expressed in the line Cd-Ri. It was supposed that both the phytochelatins and the Cd-binding proteins contribute to the resisitance of N. plumbaginifolia callus lines to cadmium and the lack of the phytochelatins can be equilibrated by the changes in the low-molecular Cd-binding protein synthesis.

  9. Cadmium accumulation and biochemical responses in Sparus aurata following sub-lethal Cd exposure.

    Science.gov (United States)

    Isani, G; Andreani, G; Cocchioni, F; Fedeli, D; Carpené, E; Falcioni, G

    2009-01-01

    Cadmium (Cd), a heavy metal with limited biological function, is widely distributed in the aquatic environment as a result of natural and anthropogenic activities. The effect of 4 and 11 days exposure of gilthead sea bream Sparus aurata to sub-lethal concentrations of Cd was evaluated as levels of Cd content and Cd-metallothionein (MT) presence in different organs. The possible genotoxic effect was also evaluated in erythrocytes by using the "comet assay", a promising tool for estimating DNA damage at the single-cell level. The results obtained show that in the controls, Cd content was significantly higher in gills compared to in liver, but the treatment of fish with 0.1mg/l Cd induced a stronger accumulation of metal in liver depending on the length of the exposure period. Cd traces were found in plasma, muscle and kidney. Cd forms complexes in the cytosol with MT only in the liver but Cd-MT content significantly increased after 11 days of exposure to the metal, while after 4 days of treatment the protein level was similar to the control. The "comet assay" performed on S. aurata eryhtrocytes isolated from fish treated for 4 and 11 days with 0.1mg/l Cd, showed that there was no DNA damage at both exposure periods.

  10. Overcoming Etch Challenges on a 6″ Hg1- x Cd x Te MBE on Si Wafer

    Science.gov (United States)

    Apte, Palash; Norton, Elyse; Robinson, Solomon

    2017-10-01

    The effect of increasing photoresist (PR) thickness on the inductively coupled plasma (ICP) dry etched characteristics of a 6″ (c.15 cm) molecular beam epitaxy Hg1- x Cd x Te/Si wafer is investigated. It is determined that the Hg1- x Cd x Te etch rate (ER) does not vary significantly with a change in the PR thickness. Also, the vertical ER of the PR is seen to be independent of the PR thickness, but the lateral ER is seen to reduce significantly with increased PR thickness. Indeed, very little reduction in the pixel mesa area post-dry etch is seen for the thicker PR. Consequently, the trench sidewall angle is also seen to vary as a function of the PR thickness. Since ICP is the more attractive choice for dry etching Hg1- x Cd x Te, this simple, cost-effective way to extend the capabilities of dry etching (larger mesa top area post-dry etch, ability to create tailor-made trench sidewall angles for optimal conformal passivation deposition, and potential for reduced dry etch damage) described here would allow for the fabrication of next generation infrared detectors with increased yield and reduced cost. Although similar results have been presented using the electron cyclotron resonance system to dry etch Hg1- x Cd x Te, to the best of our knowledge, this is the first time that such results have been presented using an ICP system.

  11. Status of HgCdTe Barrier Infrared Detectors Grown by MOCVD in Military University of Technology

    Science.gov (United States)

    Kopytko, M.; Jóźwikowski, K.; Martyniuk, P.; Gawron, W.; Madejczyk, P.; Kowalewski, A.; Markowska, O.; Rogalski, A.; Rutkowski, J.

    2016-09-01

    In this paper we present the status of HgCdTe barrier detectors with an emphasis on technological progress in metalorganic chemical vapor deposition (MOCVD) growth achieved recently at the Institute of Applied Physics, Military University of Technology. It is shown that MOCVD technology is an excellent tool for HgCdTe barrier architecture growth with a wide range of composition, donor /acceptor doping, and without post-grown annealing. The device concept of a specific barrier bandgap architecture integrated with Auger-suppression is as a good solution for high-operating temperature infrared detectors. Analyzed devices show a high performance comparable with the state-of-the-art of HgCdTe photodiodes. Dark current densities are close to the values given by "Rule 07" and detectivities of non-immersed detectors are close to the value marked for HgCdTe photodiodes. Experimental data of long-wavelength infrared detector structures were confirmed by numerical simulations obtained by a commercially available software APSYS platform. A detailed analysis applied to explain dark current plots was made, taking into account Shockley-Read-Hall, Auger, and tunneling currents.

  12. Facile synthesis of N-acetyl-L-cysteine capped CdHgSe quantum dots and selective determination of hemoglobin.

    Science.gov (United States)

    Wang, Qingqing; Zhan, Guoqing; Li, Chunya

    2014-01-03

    Using N-acetyl-L-cysteine (NAC) as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared NAC capped CdHgSe quantum dots were thoroughly characterized by fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. A novel method for the selective determination of hemoglobin (Hb) was developed based on fluorescence quenching of the NAC capped CdHgSe quantum dots. A number of key factors including pH value of phosphate buffer solution, quantum dots concentration, the adding sequence of reagents and reaction time that influence the analytical performance of the NAC capped CdHgSe quantum dots in Hb determination were investigated. Under the optimal experimental conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of Hb in the range of 4.0×10(-9)-4.4×10(-7) mol L(-1) with a detection limit of 2.0×10(-9) mol L(-1). The developed method has been successfully employed to determine Hb in human urine samples.

  13. Water Soluble Cationic Porphyrin Sensor for Detection of Hg2+, Pb2+, Cd2+, and Cu2+

    Directory of Open Access Journals (Sweden)

    Matibur Zamadar

    2016-01-01

    Full Text Available Here we report the sensing properties of the aqueous solution of meso-tetra(N-methyl-4-pyridylporphine tetrachloride (1 for simultaneous detection of toxic metal ions by using UV-vis spectroscopy. Cationic porphyrin 1 displayed different electronic absorptions in UV-vis region upon interacting with Hg2+, Pb2+, Cd2+, and Cu2+ ions in neutral water solution at room temperature. Quite interestingly, the porphyrin 1 showed that it can function as a single optical chemical sensor and/or metal ion receptor capable of detecting two or more toxic metal ions, particularly Hg2+, Pb2+, and Cd2+ ions coexisting in a water sample. Porphyrin 1 in an aqueous solution provides a unique UV-vis sensing system for the determination of Cd2+ in the presence of larger metal ions such as Hg2+, or Pb2+. Finally, the examination of the sensing properties of 1 demonstrated that it can operate as a Cu2+ ion selective sensor via metal displacement from the 1-Hg2+, 1-Pb2+, and 1-Cd2+.

  14. First-principles study of structure and nonlinear optical properties of CdHg(SCN)4 crystal

    Institute of Scientific and Technical Information of China (English)

    张鹏; 孔垂岗; 郑超; 王新强; 马跃; 冯金波; 矫玉秋; 卢贵武

    2015-01-01

    The geometric structure, electronic structure, and optical properties of CdHg(SCN)4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approximation. The band gap of CdHg(SCN)4 crystal is calculated to be 3.198 eV, which is in good agreement with the experimental value 3.265 eV. The calculated second-order nonlinear optical coefficients are d14=1.2906 pm/V and d15=5.0928 pm/V, which are in agreement with the experimental results (d14=(1.4 ± 0.6) pm/V and d15=(6.0 ± 0.9) pm/V). Moreover, it is found that the contribution to the valence band mainly comes from Cd-4d, Hg-5d states, and the contributions to the valence band top and the conduction band bottom predominantly come from C-2p, N-2p, and S-3p states. The second-order nonlinear optical effect of CdHg(SCN)4 crystal results mainly from the internal electronic transition of (SCN)−.

  15. Megapixel mercury cadmium telluride focal plane arrays for infrared imaging out to 12 microns Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the fabrication of large format, long wave infrared (LWIR) mercury cadmium telluride (HgCdTe or MCT) detector arrays where the cutoff wavelength is...

  16. Sublethal effects of cadmium, manganese, lead, zinc and iron on the ...

    African Journals Online (AJOL)

    caleb

    implied that heavy metals have toxic effects and plasma electrolyte is a useful tool for early detection and diagnosis of ... essential metals, such as arsenic (As), mercury (Hg), cadmium (Cd) and ... underlying electrolyte imbalances can prevent.

  17. High-Operating Temperature HgCdTe: A Vision for the Near Future

    Science.gov (United States)

    Lee, D.; Carmody, M.; Piquette, E.; Dreiske, P.; Chen, A.; Yulius, A.; Edwall, D.; Bhargava, S.; Zandian, M.; Tennant, W. E.

    2016-09-01

    We review recent advances in the HgCdTe material quality and detector performance achieved at Teledyne using molecular beam epitaxy growth and the double-layer planar hetero-junction (DLPH) detector architecture. By using an un-doped, fully depleted absorber, Teledyne's DLPH architecture can be extended for use in high operating temperatures and other applications. We assess the potential achievable performance for long wavelength infrared (LWIR) hetero-junction p-lightly-doped n or p-intrinsic- n (p-i-n) detectors based on recently reported results for 10.7 μm cutoff 1 K × 1 K focal plane arrays (FPAs) tested at temperatures down to 30 K. Variable temperature dark current measurements show that any Shockley-Read-Hall currents in the depletion region of these devices have lifetimes that are reproducibly greater than 100 ms. Under the assumption of comparable lifetimes at higher temperatures, it is predicted that fully-depleted background radiation-limited performance can be expected for 10- μm cutoff detectors from room temperature to well below liquid nitrogen temperatures, with room-temperature dark current nearly 400 times lower than predicted by Rule 07. The hetero-junction p-i-n diode is shown to have numerous other significant potential advantages including minimal or no passivation requirements for pBn-like processing, low 1/ f noise, compatibility with small pixel pitch while maintaining high modulation transfer function, low crosstalk and good quantum efficiency. By appropriate design of the FPA dewar shielding, analysis shows that dark current can theoretically be further reduced below the thermal equilibrium radiative limit. Modeling shows that background radiation-limited LWIR HgCdTe operating with f/1 optics has the potential to operate within √2 of background-limited performance at 215 K. By reducing the background radiation by 2/3 using novel shielding methods, operation with a single-stage thermo-electric-cooler may be possible. If the

  18. Multi-color IRFPAs made from HgCdTe grown by MOVPE

    Science.gov (United States)

    Jones, C. L.; Hipwood, L. G.; Price, J.; Shaw, C. J.; Abbott, P.; Maxey, C. D.; Lau, H. W.; Catchpole, R. A.; Ordish, M.; Knowles, P.; Gordon, N. T.

    2007-04-01

    The drive towards improved target recognition has led to an increasing interest in detection in more than one infrared band. This paper describes the design, fabrication and performance of two-colour and three-colour infrared detectors made from HgCdTe grown by Metal Organic Vapour Phase Epitaxy (MOVPE). The detectors are staring, focal plane arrays consisting of HgCdTe mesa-diode arrays bump bonded to silicon read-out integrated circuits (ROICs). Each mesa diode has one connection to the ROIC and the colours are selected by varying the applied bias. Results will be presented for both two-colour and three-colour devices. In a two-colour n-p-n design the cut-off wavelengths are defined by the compositions of the two n-type absorbers and the doping and composition of the p-type layer are chosen to prevent transistor action. The bias polarity is used to switch the output between colours. This design has been used to make MW/LW detectors with a MW band covering 3 to 5 μm and a LW band covering 5 to 10 μm. In a three-colour n-p-n design the cut-off wavelengths are defined by the compositions of the two n-type absorbers and the p-type absorber, which has an intermediate cut-off wavelength. The absorbers are separated from each other by electronic barriers consisting of wide band-gap material. At low applied bias these barriers prevent photo-electrons generated in the p-type absorber from escaping and the device then gives an output from one of the n-type absorbers. At high applied bias the electronic barrier is pulled down and the device gives an output from both the p-type absorber and one of the n-type absorbers. Thus by varying the polarity and magnitude of the bias it is possible to obtain three-colours from a two-terminal device. This design has been used to make a SW/MW/MW detector with cut-off wavelengths of approximately 3, 4 and 6 μm.

  19. An in vitro model for the in vivo mobilization of cadmium by chelating agents using 113Cd-NMR spectroscopy.

    Science.gov (United States)

    Beaty, J A; Jones, M M; Wilson, D J; Ma, L

    1992-01-01

    An in vitro method, based on 113Cd-NMR spectroscopy, that provides an alternative to the use of animals for an initial screening of cadmium antagonists is presented. The relative values of the effective stability constants of potential chelating antagonists for cadmium are estimated by using 113Cd-NMR spectroscopy to determine the concentrations of the cadmium species involved in appropriate competitive equilibria. This is accomplished via an examination of the competition between the proposed antagonist and EDTA (ethylenediaminetetraacetic acid) for cadmium-113; previously, EDTA has been shown to be capable of removing cadmium from such in vivo binding sites as metallothionein. The reactions proceed via the stepwise addition of three dithiocarbamate groups to the cadmium accompanied by the concurrent stepwise release of donor groups from the EDTA. The resulting 113Cd-NMR data allow for the determination of the overall stability constant for the complex formed between cadmium and N-methyl-D-glucamine dithiocarbamate, iminodiacetic acid dithiocarbamate, proline dithiocarbamate, sarcosine dithiocarbamate. The use of 113Cd-NMR spectroscopy has the potential for providing direct evidence on the effectiveness of chelate antagonists to compete with endogenous ligands for other toxic metal ions. This technique could prove very useful for other compounds that are not stable enough toward acid and/or base to be examined by standard titrimetric methods.

  20. HgCdTe technology in Germany: the past, the present, and the future

    Science.gov (United States)

    Cabanski, W.; Ziegler, J.

    2009-05-01

    The first HgCdTe (MCT) activities at AEG-Telefunken in Germany were started in 1976. As part of the closing of AEG, the Heilbronn based IR-technology division was established as a spin-off company in 1995, under the brand name of AIM Infrarot-Module GmbH. A rapidly growing team of scientists focused on the detector-dewar-cooler technology and the development of linear photoconductive MCT arrays by applying the solid-state-recrystallization (SSR) technique for MCT growth, depositing and thinning MCT on sapphire substrates and oxide passivation. In 1979, after successful development of an own MCT-technology base, AEG-Telefunken entered into a license agreement with Texas Instruments for US Common Module (CM) technology in order to speed up the entry into full scale production with a transfer of MCT-material, dewar and cooler processes. CMs are still manufactured in small numbers. At the same time, a proprietary pc-MCT technology, independent of the CM production line, was developed and continuously matured and is today successfully applied in various custom designs like detectors for smart ammunition, for commercial and space applications. In 1982 started the development of 2nd Gen. photovoltaic MCT detectors, based on liquid-phase-epitaxy (LPE) in tilting and dipping technique and on planar array technology with Hg-Diffusion and ion implantation for pn-junction formation and CdTe/ZnS passivation. Linear MCT arrays in the 8-10,5 μm wavelength range with state of the art electro-optical performance have rapidly been demonstrated. Within the frame of the European anti-tank program TRIGAT, a two-way know-how-transfer between AEGTelefunken and SOFRADIR was established for linear LW MCT array processing, flip-chip-technology and dewar technology. Today, AIM's 2nd Gen. portfolio is based on MCT-LPE in dipping technique on CdZnTe substrates, characterized by a very low defect and dislocation density for 0,9 μm to 15μm wavelength application. Array processing is performed

  1. Interface morphology studies of liquid phase epitaxy grown HgCdTe films by atomic force microscopy

    Science.gov (United States)

    Azoulay, M.; George, M. A.; Burger, A.; Collins, W. E.; Silberman, E.

    1994-04-01

    In this paper we report an investigation of the morphology of the interfaces of liquid phase epitaxy (LPE) grown HgCdTe thin films on CdTe and CdZnTe substrates by atomic force microscopy (AFM) on freshly cleaved (110) crystallographic planes. An empirical observation which may be linked to lattice mismatch was indicated by an angle between the cleavage steps of the substrate to those of the film. The precipitates with size ranging from 5 nm to 20 nm were found to be most apparent near the interface.

  2. Passivation Effect of Atomic Layer Deposition of Al2O3 Film on HgCdTe Infrared Detectors

    Science.gov (United States)

    Zhang, Peng; Ye, Zhen-Hua; Sun, Chang-Hong; Chen, Yi-Yu; Zhang, Tian-Ning; Chen, Xin; Lin, Chun; Ding, Ring-Jun; He, Li

    2016-09-01

    The passivation effect of atomic layer deposition of (ALD) Al2O3 film on a HgCdTe infrared detector was investigated in this work. The passivation effect of Al2O3 film was evaluated by measuring the minority carrier lifetime, capacitance versus voltage ( C- V) characteristics of metal-insulator-semiconductor devices, and resistance versus voltage ( R- V) characteristics of variable-area photodiodes. The minority carrier lifetime, C- V characteristics, and R- V characteristics of HgCdTe devices passivated by ALD Al2O3 film was comparable to those of HgCdTe devices passivated by e-beam evaporation of ZnS/CdTe film. However, the baking stability of devices passivated by Al2O3 film is inferior to that of devices passivated by ZnS/CdTe film. In future work, by optimizing the ALD Al2O3 film growing process and annealing conditions, it may be feasible to achieve both excellent electrical properties and good baking stability.

  3. Ion Exchange Processed CdS Nanorods in Powder Form Using Cadmium Hydroxide Nanowires By Wet Chemical Route

    Directory of Open Access Journals (Sweden)

    Savita L. Patil

    2010-06-01

    Full Text Available Simple, inexpensive and soft chemical route (wet chemical method was employed for the synthesis of bulk forms of cadmium hydroxide [Cd(OH2] nanowires bundles and their conversion to cadmium sulphide [CdS] nanorods at room temperature by simple anion exchange route. Due to difference in solubility product and diffusion rates of the Cd(OH2 and CdS, the anion exchange reaction was taken place and CdS nanorods were formed. CdS nanorods were characterized by X-ray diffraction (XRD, and scanning electron microscopy (SEM, energy-dispersive X-ray (EDX analysis. Since CdS is semi-conducting material, it has variety of potential applications, this work demonstrates a cost effective method for the synthesis of CdS nanorods in bulk form like CNT.

  4. $^{111m}$Cd- and $^{199m}$Hg-derivatives of blue oxidases

    CERN Multimedia

    2002-01-01

    The rack-induced bonding concept (H.B.Gray & B.G.~Malmstroem, Comments Inorg. Chem, 2, 203, 1983) postulates that the bound metal ion in metalloproteins is forced to adopt a coordination geometry determined by the rigid peptide conformation of the protein. Alternatively, the metal ion could create its own favoured coordination geometry in a soft peptide conformation. In order to decide who is slave or master the changes of coordination and rigidity of metal sites in blue copper proteins due to metal and ligand exchange were studied by $^{111m}$Cd and $^{199m}$Hg $\\gamma$-$\\gamma$-perturbed angular correlation (PAC). To get a better understanding of the so called " Type 1 Copper Site " of the blue oxidases laccase (LAC) and ascorbate oxidase (AO) we concentrated our investigations on the small blue copper proteins azurin and plastocyanin. \\\\ \\\\In azurin~(Az), the metal ligand methionine 121~(M121) was replaced by several amino acids, e.g. asparagine~(N), glutamic acid~(E), via site directed mutagenesis. Di...

  5. Two-color HgCdTe infrared staring focal plane arrays

    Science.gov (United States)

    Smith, Edward P.; Pham, Le T.; Venzor, Gregory M.; Norton, Elyse; Newton, Michael; Goetz, Paul; Randall, Valerie; Pierce, Gregory; Patten, Elizabeth A.; Coussa, Raymond A.; Kosai, Ken; Radford, William A.; Edwards, John; Johnson, Scott M.; Baur, Stefan T.; Roth, John A.; Nosho, Brett; Jensen, John E.; Longshore, Randolph E.

    2003-12-01

    Raytheon Vision Systems (RVS) in collaboration with HRL Laboratories is contributing to the maturation and manufacturing readiness of third-generation two-color HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256x256 30μm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) spectral regions. FPAs configured for MWIR/MWIR, MWIR/LWIR and LWIR/LWIR detection are used for target identification, signature recognition and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer-heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all two-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single mesa, single indium bump, and sequential mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

  6. HOT MWIR HgCdTe performance on CZT and alternative substrates

    Science.gov (United States)

    Pellegrino, Joseph G.; DeWames, Roger; Perconti, Philip; Billman, Curtis; Maloney, Patrick

    2012-06-01

    Mid wave infrared (MWIR) imaging in the 3-5 um spectral band has traditionally been performed by InSb sensors. InSb technology is presently limited to a near 80K operating temperature and the hunt has been on for a higher operating temperature (HOT) technology that does as well at 150K as InSb at 80K, but with reduced power requirements. Amongst these alternative technologies are photovoltaic sensors consisting of heterostructures of HgCdTe (MCT). In previous work we assessed the device performance of several alternative MWIR HOT technologies (MCT on Si, MCT on GaAs) as a function of operating temperature. In this work we compare the NEDT histograms for these alternative technologies with InSb to better understand how their performance can be improved at higher temperatures. We also present analysis formalism for quantitatively assessing the number of FPA pixels which reside in the central versus the shoulder portions of the histogram.Begin the Introduction two lines below the Keywords. The manuscript should not have headers, footers, or page numbers. It should be in a onecolumn format. References are often noted in the text1 and cited at the end of the paper.

  7. Human biomonitoring for Cd, Hg and Pb in blood of inhabitants of the Sacco Valley (Italy

    Directory of Open Access Journals (Sweden)

    Sonia D'Ilio

    2013-03-01

    Full Text Available INTRODUCTION. The Sacco Valley (Lazio, Italy is characterized by high density population and several industrial chemical productions that during the time had led to a substantial amount of by-products. The result was a severe environmental pollution of the area and in particular of the river Sacco. In 1991, the analysis of water and soils samples of three industrial landfills revealed the presence of organochlorine compounds and heavy metals. A research project named "Health of residents living in Sacco Valley area", coordinated by the regional Department of Epidemiology, was undertaken and financed to evaluate the state of health of the population living near those polluted areas. MATERIALS AND METHODS. Cd, Hg and Pb were quantified in 246 blood samples of potentially exposed residents of the Sacco Valley by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS. RESULTS. Individuals who agreed to be sampled did not exhibit high levels of the elements. The distance from the river does not seem to be directly connected with the elements levels in blood. The contribution of these contaminants to the total intake due to ingestion of food was difficult to evaluate. The unclear trend of data would require a characterization of the polluted site with environmental sampling of different matrices.

  8. Optical absorption, induced bleaching, and photoluminescence of CdSe nanoplatelets grown in cadmium octanoate matrix

    Science.gov (United States)

    Lyashchova, Alina; Dmytruk, Andriy; Dmitruk, Igor; Klimusheva, Gertruda; Mirnaya, Tetyana; Asaula, Vitaliy

    2014-02-01

    CdSe nanoparticles (NPs) are chemically synthesized in thermotropic ionic liquid crystalline (LC) phase of cadmium octanoate that was used as a nanoreactor. The nanocomposite samples are obtained by the rapid cooling of the LC phase to room temperature. Observed doublet structure in absorption spectra of the nanocomposites is characteristic for the two-dimensional CdSe nanoplatelets (NPLs). The thicknesses of the CdSe NPLs are 1.6, 1.9 and 2.3 nm as determined from the absorption spectra, and correspond to 4, 5 and 6 CdSe monolayers, respectively. Induced simultaneous bleaching of the doublet components observed under femtosecond laser excitation, as well as photoluminescence spectra and their kinetics are found compatible with the model of excitons with heavy- and light-hole valence bands confined in nanoplatelets.

  9. 113Cd-NMR investigation of a cadmium-substituted copper, zinc-containing superoxide dismutase from yeast

    DEFF Research Database (Denmark)

    Kofod, Pauli; Bauer, Rogert; Danielsen, Eva

    1991-01-01

    113Cd nuclear magnetic resonance spectroscopy has been used to investigate the metal binding sites of cadmium-substituted copper,zinc-containing superoxide dismutase from baker's yeast. NMR signals were obtained for 113Cd(II) at the Cu site as well as for 113Cd(II) at the Zn site. The two subunits...... an explanation for the discrepancy in the literature regarding 113Cd-NMR investigations of bovine superoxide dismutase....

  10. Different growth response of Euglena gracilis to Hg, Cd, Cr and Ni compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gajdosova, J. [Institute of Preventive and Clinical Medicine, Limbova 14, Bratislava (Slovakia); Reichrtova, E. [Institute of Preventive and Clinical Medicine, Limbova 14, Bratislava (Slovakia)

    1996-03-01

    The toxicity of inorganic mercury, nickel, chromium and cadmium on the unicellular photosynthetic flagellate Euglena gracilis, strain Z (E.g.) has been tested. Under the conditions used each metal impaired the growth rate of E.g., and had a very strong effect on cell motility. The degree of cytotoxicity and motility decreased from mercury iodide to cadmium chloride to cadmium nitrate to potassium dichromate to nickel sulfate. No mutagenic effects of the metals investigated have been observed. Adverse effects of metal compounds can be tested on the eukaryotic species of Euglena gracilis used as an intermediate model system between bacterial and animal model. (orig.). With 2 figs.

  11. Cadmium-zinc accumulation and photosystem II responses of Noccaea caerulescens to Cd and Zn exposure.

    Science.gov (United States)

    Bayçu, Gülriz; Gevrek-Kürüm, Nurbir; Moustaka, Julietta; Csatári, István; Rognes, Sven Erik; Moustakas, Michael

    2017-01-01

    A population of the metallophyte Noccaea (Thlaspi) caerulescens originating from a Zn-enriched area at Røros Copper Mine (Norway) was studied. N. caerulescens tolerance to accumulate Cd and Zn was evaluated in hydroponic experiments by chlorophyll fluorescence imaging analysis. In the field-collected N. caerulescens mother plants, Zn shoot concentrations were above Zn hyperaccumulation threshold while, in hydroponic experiments under 40-μM Cd exposure, shoot Cd concentrations were clearly above Cd hyperaccumulation threshold. Cadmium ions and, to a less extent, Zn were mainly retained in the roots. Exposure to Cd enhanced Zn translocation to the shoot, while decreased significant total Ca(2+) uptake, suggesting that Cd uptake occurs through Ca(2+) transporters. Nevertheless, it increased Ca(2+) translocation to the leaf, possibly for photoprotection of photosystem II (PSII). Exposure to 800 μM Zn or 40 μM Cd resulted in increased Fe(3+) uptake suggesting that in N. caerulescens, Cd uptake does not take place through the pathway of Fe(3+) uptake and that conditions that lead to Cd and Zn accumulation in plants may also favor Fe accumulation. Despite the significant high toxicity levels of Zn and Cd in leaves, under Zn and Cd exposure, respectively, the allocation of absorbed light energy at PSII did not differ compared to controls. The results showed that N. caerulescens keep Cd and Zn concentrations in the mesophyll cells in non-toxic forms for PSII and that the increased Ca and Fe accumulation in leaves alleviates the toxicity effects. Chlorophyll fluorescence imaging revealed that PSII of N. caerulescens resisted better the phytotoxic effects of 20 times higher Zn than Cd exposure concentration. Overall, it is concluded that the use of chlorophyll fluorescence imaging constitutes a promising basis for investigating heavy metal tolerance of plants.

  12. Cadmium (Cd) distribution and contamination in Chinese paddy soils on national scale.

    Science.gov (United States)

    Liu, Xiaojuan; Tian, Guangjin; Jiang, Dong; Zhang, Chi; Kong, Lingqiang

    2016-09-01

    Rice is a staple food by an increasing number of people in China. As more issues have arisen in China due to rice contaminated by cadmium (Cd), Cd contamination in arable soils has become a severe problem. In China, many studies have examined Cd contamination in arable soils on a national scale, but little studies have focused on the distribution of Cd in paddy fields. This study explored the spatial pattern of Cd in paddy soils in China, made a preliminary evaluation of the potential risk, and identified the most critically contaminated regions based on the domestic rough rice trade flow. The results showed that Cd concentrations in paddy soils in China ranged from 0.01 to 5.50 mg/kg, with a median value of 0.23 mg/kg. On average, the highest Cd concentrations were in Hunan (0.73 mg/kg), Guangxi (0.70 mg/kg), and Sichuan (0.46 mg/kg) provinces. Cd concentrations in paddy soils in central and western regions were higher than those in eastern regions, especially the southeastern coastal regions. Of the administrative regions, Cd standard exceedance rate was 33.2 %, and the heavy pollution rate was 8.6 %. Regarding to Cd of paddy soil, soil environmental quality was better in Northeast China Plain than in Yangtze River Basin and southeastern coastal region. Mining activities were the main anthropogenic pollution source of Cd in Chinese paddy soil. Based on rice trade, more of the Chinese population would be exposed to Cd through intake of rice produced in Hunan province. Certain regions that output rice, especially Hunan province, should be given priority in the management and control of Cd contamination in paddy soil.

  13. Comparison of a static and a dynamic in vitro model to estimate the bioaccessibility of As, Cd, Pb and Hg from food reference materials Fucus sp. (IAEA-140/TM) and Lobster hepatopancreas (TORT-2)

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Escribano, Silvia [Instituto de Agroquimica y Tecnologia de Alimentos (IATA-CSIC), Apdo. 73, 46100, Burjassot, Valencia (Spain); Denis, Sylvain; Blanquet-Diot, Stephanie [Clermont Universite, Universite d' Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception ingenierie et developpement de l' aliment et du medicament, BP 10448, F-63000 Clermont-Ferrand (France); Calatayud, Marta [Instituto de Agroquimica y Tecnologia de Alimentos (IATA-CSIC), Apdo. 73, 46100, Burjassot, Valencia (Spain); Barrios, Laura [Departamento de Informatica Cientifica (SGAI-CSIC), C/ Pinar 19, 28006 Madrid (Spain); Velez, Dinoraz, E-mail: deni@iata.csic.es [Instituto de Agroquimica y Tecnologia de Alimentos (IATA-CSIC), Apdo. 73, 46100, Burjassot, Valencia (Spain); Alric, Monique [Clermont Universite, Universite d' Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception ingenierie et developpement de l' aliment et du medicament, BP 10448, F-63000 Clermont-Ferrand (France); Montoro, Rosa [Instituto de Agroquimica y Tecnologia de Alimentos (IATA-CSIC), Apdo. 73, 46100, Burjassot, Valencia (Spain)

    2011-01-01

    Bioaccessibility, the fraction of an element solubilized during gastrointestinal digestion and available for absorption, is a factor that should be considered when evaluating the health risk of contaminants from food. Static and dynamic models that mimic human physiological conditions have been used to evaluate bioaccessibility. This preliminary study compares the bioaccessibility of arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) in two food certified reference materials (CRMs) (seaweed: Fucus sp., IAEA-140/TM; Lobster hepatopancreas: TORT-2), using two in vitro gastrointestinal digestion methods: a static method (SM) and a dynamic multicompartment method (TIM-1). There are significant differences (p < 0.05) between the bioaccessible values of As, Cd, Pb and Hg obtained by SM and TIM-1 in the two CRMs. The specific form in which the elements studied are present in the CRM may help to explain the bioaccessibility values obtained. - Research Highlights: {yields}Data are reported for As, Cd, Pb and Hg bioaccessibility from food CRMs. {yields}The static and TIM-1 methods give significantly different bioaccessibility values. {yields}The possible influence of speciation on bioaccessibility is discussed. {yields}To improve bioaccessibility quality data, food reference materials are needed.

  14. Cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Stoeppler, M. (Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Angewandte Physikalische Chemie); Piscator, M. (Karolinska Inst., Stockholm (Sweden). Dept. of Environmental Hygiene) (eds.)

    1988-01-01

    The proceedings contain the 18 papers presented at the workshop. They are dealing with the following themes: Toxicity, carcinogenesis and metabolism of cadmium, epidemiology; environmental occurrence; quantitative analysis and quality assessment. (MG) With 57 figs., 79 tabs.

  15. Hg1-xCdxTe vapor deposition on CdZnTe substrates by Closed Space Sublimation technique

    Science.gov (United States)

    Rubio, Sandra; Sochinskii, Nikolai V.; Repiso, Eva; Tsybrii, Zinoviia; Sizov, Fiodor; Plaza, Jose Luis; Diéguez, Ernesto

    2017-01-01

    Closed Space Sublimation (CSS) technique has been studied to deposit Hg1-xCdxTe polycrystalline films on CdZnTe substrates at the improved pressure-temperature conditions. The experimental results on film characterization suggest that the CSS optimal conditions are the argon atmospheric pressure (1013 mbar) and the deposition temperature in the range of 500-550 °C. These conditions provide macro-defect free Hg1-xCdxTe films with the uniform size and surface distribution of polycrystals.

  16. Minimizing Reflectivity by Etching Microstructures in Mercury Cadmium Telluride (HgCdTe)

    Science.gov (United States)

    2013-02-01

    readout integrated circuit (ROIC) (figure 1) using a p-n junction, which collects the photocharge into pixels using electric fields, and indium bump ...by ICP, a dry etch technique (figure 4). The samples were first mounted to a Si wafer with Apiezon N adhesive and loaded into the plasma etcher...flowing helium (He) gas on the backside of the handle wafer . The kinetic energy of the ionized gases bombards the sample and physically removes

  17. Proton irradiation results for long-wave HgCdTe infrared detector arrays for Near-Earth Object Camera

    Science.gov (United States)

    Dorn, Meghan L.; Pipher, Judith L.; McMurtry, Craig; Hartman, Spencer; Mainzer, Amy; McKelvey, Mark; McMurray, Robert; Chevara, David; Rosser, Joshua

    2016-07-01

    HgCdTe detector arrays with a cutoff wavelength of ˜10 μm intended for the Near-Earth Object Camera (NEOCam) space mission were subjected to proton-beam irradiation at the University of California Davis Crocker Nuclear Laboratory. Three arrays were tested-one with 800-μm substrate intact, one with 30-μm substrate, and one completely substrate-removed. The CdZnTe substrate, on which the HgCdTe detector is grown, has been shown to produce luminescence in shorter wave HgCdTe arrays that causes an elevated signal in nonhit pixels when subjected to proton irradiation. This testing was conducted to ascertain whether or not full substrate removal is necessary. At the dark level of the dewar, we detect no luminescence in nonhit pixels during proton testing for both the substrate-removed detector array and the array with 30-μm substrate. The detector array with full 800-μm substrate exhibited substantial photocurrent for a flux of 103 protons/cm2 s at a beam energy of 18.1 MeV (˜750 e-/s) and 34.4 MeV (˜65 e-/s). For the integrated space-like ambient proton flux level measured by the Spitzer Space Telescope, the luminescence would be well below the NEOCam dark current requirement of <200 e-/s, but the pattern of luminescence could be problematic, possibly complicating calibration.

  18. Threading and misfit-dislocation motion in molecular-beam epitaxy-grown HgCdTe epilayers

    Science.gov (United States)

    Carmody, M.; Lee, D.; Zandian, M.; Phillips, J.; Arias, J.

    2003-07-01

    Lattice mismatch between the substrate and the absorber layer in single-color HgCdTe infrared (IR) detectors and between band 1 and band 2 in two-color detectors results in the formation of crosshatch lines on the surface and an array of misfit dislocations at the epi-interfaces. Threading dislocations originating in the substrate can also bend into the interface plane and result in misfit dislocations because of the lattice mismatch. The existence of dislocations threading through the junction region of HgCdTe IR-photovoltaic detectors can greatly affect device performance. High-quality CdZnTe substrates and controlled molecular-beam epitaxy (MBE) growth of HgCdTe can result in very low threading-dislocation densities as measured by the etch-pit density (EPD ˜ 104cm-2). However, dislocation gettering to regions of high stress (such as etched holes, voids, and implanted-junction regions) at elevated-processing temperatures can result in a high density of dislocations in the junction region that can greatly reduce detector performance. We have performed experiments to determine if the dislocations that getter to these regions of high stress are misfit dislocations at the substrate/absorber interface that have a threading component extending to the upper surface of the epilayer, or if the dislocations originate at the cap/absorber interface as misfit dislocations. The preceding mechanisms for dislocation motion are discussed in detail, and the possible diode-performance consequences are explored.

  19. Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico).

    Science.gov (United States)

    Ruelas-Inzunza, J; Green-Ruiz, C; Zavala-Nevárez, M; Soto-Jiménez, M

    2011-08-15

    With the purpose of knowing seasonal variations of Cd, Cr, Hg and Pb in a river basin with past and present mining activities, elemental concentrations were measured in six fish species and four crustacean species in Baluarte River, from some of the mining sites to the mouth of the river in the Pacific Ocean between May 2005 and March 2006. In fish, highest levels of Cd (0.06 μg g ⁻¹ dry weight) and Cr (0.01 μg g⁻¹) were detected during the dry season in Gobiesox fluviatilis and Agonostomus monticola, respectively; the highest levels of Hg (0.56 μg g⁻¹) were detected during the dry season in Guavina guavina and Mugil curema. In relation to Pb, the highest level (1.65 μg g⁻¹) was detected in A. monticola during the dry season. In crustaceans, highest levels of Cd (0.05 μg g⁻¹) occurred in Macrobrachium occidentale during both seasons; highest concentration of Cr (0.09 μg g⁻¹) was also detected in M. occidentale during the dry season. With respect to Hg, highest level (0.20 μg g⁻¹) was detected during the rainy season in Macrobrachium americanum; for Pb, the highest concentration (2.4 μg g⁻¹) corresponded to Macrobrachium digueti collected in the dry season. Considering average concentrations of trace metals in surficial sediments from all sites, Cd (pseason. Biota sediment accumulation factors above unity were detected mostly in the case of Hg in fish during both seasons. On the basis of the metal levels in fish and crustacean and the provisional tolerable weekly intake of studied elements, people can eat up to 13.99, 0.79 and 2.34 kg of fish in relation to Cd, Hg and Pb, respectively; regarding crustaceans, maximum amounts were 11.33, 2.49 and 2.68 kg of prawns relative to levels of Cd, Hg and Pb, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. HgCdTe探测器应力的多重晶X射线衍射分析%Multiple crystal X - ray diffraction analysis of stress in HgCdTe photovoltaic detector

    Institute of Scientific and Technical Information of China (English)

    孙涛; 王庆学; 陈文桥; 梁晋穗; 陈兴国; 胡晓宁; 李言谨; 何力

    2004-01-01

    HgCdTe光伏探测器的钝化介质膜应力常常限制其低温性能,利用高分辨率多重晶X射线衍射仪中的三重晶衍射技术和倒易空间作图对钝化介质膜应力进行了表征,发现在较高溅射能量下沉积的钝化膜,由于应力的作用,HgCdTe晶片出现弯曲,并有大量镶嵌结构,而在较低的溅射能量下和热蒸发下沉积的钝化膜,晶面未出现明显弯曲,可获得较低应力的钝化介质层.

  1. Development of radiopure cadmium tungstate crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd to search for double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Danevich, F. A.; Boiko, R. S.; Chernyak, D. M.; Kobychev, V. V.; Kropivyansky, B. N.; Mokina, V. M.; Nikolaiko, A. S.; Poda, D. V.; Podviyanuk, R. B.; Tretyak, V. I. [Institute for Nuclear Research, Kyiv (Ukraine); Barabash, A. S.; Konovalov, S. I.; Umatov, V. I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Belli, P.; Bernabei, R.; D' Angelo, S. [INFN, Section of Rome Tor Vergata, Rome, Italy and Department of Physics, University of Rome Tor Vergata, Rome (Italy); Brudanin, V. B. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Cappella, F.; Incicchitti, A. [INFN, Section of Rome La Sapienza, Rome, Italy and Department of Physics, University of Rome La Sapienza, Rome (Italy); Caracciolo, V. [INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy and Department of Physics, University of L' Aquila, L' Aquila (Italy); and others

    2013-08-08

    Cadmium tungstate crystal scintillators enriched in {sup 106}Cd up to 66% ({sup 106}CdWO{sub 4}) and in {sup 116}Cd up to 82% ({sup 116}CdWO{sub 4}) have been developed. The low radioactive contamination of the crystals measured on the level of ≤ 1.5 mBq/kg ({sup 40}K), ≤ 0.005 - 0.012 mBq/kg ({sup 226}Ra), 0.04 - 0.07 mBq/kg ({sup 228}Th) allows to carry out high sensitivity experiments to search for double beta processes in {sup 106}Cd and {sup 116}Cd.

  2. Effect of plant growth-promoting rhizobacteria inoculation on cadmium (Cd) uptake by Eruca sativa.

    Science.gov (United States)

    Kamran, Muhammad Aqeel; Syed, Jabir Hussain; Eqani, Syed Ali Musstjab Akber Shah; Munis, Muhammad Farooq Hussain; Chaudhary, Hassan Javed

    2015-06-01

    Microbe-assisted phyto-remediation approach is widely applied and appropriate choice to reduce the environmental risk of heavy metals originated from contaminated soils. The present study was designed to screen out the nested belongings of Eruca sativa plants and Pseudomonas putida (ATCC 39213) at varying cadmium (Cd) levels and their potential to deal with Cd uptake from soils. We carried out pot trial experiment by examining the soil containing E. sativa seedlings either treated with P. putida and/or untreated plants subjected to three different levels (ppm) of Cd (i.e., 150, 250, and 500). In all studied cases, we observed an increase in Cd uptake for E. sativa plants inoculated with P. putida than those of un-inoculated plants. Cd toxicity was assessed by recording different parameters including stunted shoot growth, poor rooting, and Cd residual levels in the plants that were not inoculated with P. putida. Significant difference (p sativa exhibited increased values for different growth parameters (except proline contents) at lower Cd levels than those of their corresponding higher levels, shoot length (up to 27 %), root length (up to 32 %), whole fresh plant (up to 40 %), dry weight (up to 22 %), and chlorophyll contents (up to 26 %). Despite the hyperaccumulation of Cd in whole plant of E. sativa, P. putida improved the plant growth at varying levels of Cd supply than those of associated non-inoculated plants. Present results indicated that inoculation with P. putida enhanced the Cd uptake potential of E. sativa and favors the healthy growth under Cd stress.

  3. Immobilization of Cadmium in a Cd-Spiked Soil by Different Kinds of Amendments

    Directory of Open Access Journals (Sweden)

    Mahboub Saffari

    2015-07-01

    Full Text Available    Chemical stabilization of heavy metals is one of the soil remediation methods based on the application amendments to reduce mobility of heavy metals. A laboratory study was conducted to investigate the influence of different kinds of amendments on cadmium (Cd stabilization in a Cd-spiked soil. The amendments were municipal solid waste compost (MSWC, Coal fly ash (CFA, rice husk biochars prepared at 300°C (B300 and 600°C (B600, zero valent iron (Fe0 and zero valent manganese (Mn0. The Cd-spiked soils were separately incubated with selected amendments at the rates of 2 and 5% (W/W for 90 days at 25 °C. Soil samples were extracted by EDTA for periods of 5 to 975min. In addition, sequential extraction was used as a suitable method for identification of chemical forms of Cd and their plant availability. The addition of amendments to soil had significant effects on desorption and chemical forms of Cd. Changes in Cd fractions and their conversion into less soluble forms were clear in all treated soils. The addition of amendments resulted in a significant reduction in mobility factor of Cd compared to the control treatment. Among all amendments tested, Fe0 was the most effective treatment in decreasing dynamic of Cd. Biphasic pattern of Cd desorption kinetic was fitted well by the model of two first-order reactions. In general, from the practical point of view, Fe0, MSWC and Mn0 treatments are effective in Cd immobilization, while application of  Fe0 at 5% (W/W was the best treatment for stabilization of Cd

  4. HgCdTe Detectors for Space and Science Imaging: General Issues and Latest Achievements

    Science.gov (United States)

    Gravrand, O.; Rothman, J.; Cervera, C.; Baier, N.; Lobre, C.; Zanatta, J. P.; Boulade, O.; Moreau, V.; Fieque, B.

    2016-09-01

    HgCdTe (MCT) is a very versatile material system for infrared (IR) detection, suitable for high performance detection in a wide range of applications and spectral ranges. Indeed, the ability to tailor the cutoff frequency as close as possible to the needs makes it a perfect candidate for high performance detection. Moreover, the high quality material available today, grown either by molecular beam epitaxy or liquid phase epitaxy, allows for very low dark currents at low temperatures, suitable for low flux detection applications such as science imaging. MCT has also demonstrated robustness to the aggressive environment of space and faces, therefore, a large demand for space applications. A satellite may stare at the earth, in which case detection usually involves a lot of photons, called a high flux scenario. Alternatively, a satellite may stare at outer space for science purposes, in which case the detected photon number is very low, leading to low flux scenarios. This latter case induces very strong constraints onto the detector: low dark current, low noise, (very) large focal plane arrays. The classical structure used to fulfill those requirements are usually p/ n MCT photodiodes. This type of structure has been deeply investigated in our laboratory for different spectral bands, in collaboration with the CEA Astrophysics lab. However, another alternative may also be investigated with low excess noise: MCT n/ p avalanche photodiodes (APD). This paper reviews the latest achievements obtained on this matter at DEFIR (LETI and Sofradir common laboratory) from the short wave infrared (SWIR) band detection for classical astronomical needs, to long wave infrared (LWIR) band for exoplanet transit spectroscopy, up to very long wave infrared (VLWIR) bands. The different available diode architectures ( n/ p VHg or p/ n, or even APDs) are reviewed, including different available ROIC architectures for low flux detection.

  5. Uptake of cadmium by cress, lettuce and tomato in Cd-contaminated soil

    Directory of Open Access Journals (Sweden)

    J. Abedi-Koupai

    2015-06-01

    Full Text Available Increasing of water consumption and demand for irrigation water in agriculture has led to an increase in reuse of treated, or even raw, municipal and industrial wastewater in many countries. Heavy metals (HMs in these unconventional waters are one of the sources of pollution of water, soil and plant. HM toxicity in plants may eventually cause disturbances in plant growth. Accumulation of HMs in plants has health problems for human beings and animals which consume these plants. In this research, uptake of cadmium (Cd by three vegetables (cress (Lepidium sativum L., lettuce (Lactuca sativa L. and tomato (Solanum lycopersicum L. from a contaminated soil was studied. The experimental design was completely randomized. For each plant, two soil treatments (control soil and contaminated soil by 100 mg/L Cd and five replications were considered. After planting, growing and harvesting, and preparation of the samples, Cd uptake in roots and shoots was measured. Results showed that mean Cd uptake by all three plants was significantly different from the control treatment. Maximum uptake of Cd belonged to tomato, whereas lettuce had the lowest uptake. Transfer coefficient of Cd from soil into cress, lettuce and tomato was 1.3, 0.33 and 0.65, respectively. Although transfer coefficient of Cd to lettuce is lower than the other two plants, but consumption of lettuce per person is much greater than cress. Hence, irrigation management of polluted wastewater is important.

  6. Electrical and Optical Studies of Defect Structure of HgCdTe Films Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Świątek, Z.; Ozga, P.; Izhnin, I. I.; Fitsych, E. I.; Voitsekhovskii, A. V.; Korotaev, A. G.; Mynbaev, K. D.; Varavin, V. S.; Dvoretsky, S. A.; Mikhailov, N. N.; Yakushev, M. V.; Bonchyk, A. Yu.; Savytsky, H. V.

    2016-07-01

    Electrical and optical studies of defect structure of HgCdTe films grown by molecular beam epitaxy (MBE) are performed. It is shown that the peculiarity of these films is the presence of neutral defects formed at the growth stage and inherent to the material grown by MBE. It is assumed that these neutral defects are the Te nanocomplexes. Under ion milling, they are activated by mercury interstitials and form the donor centers with the concentration of 1017 cm-3, which makes it possible to detect such defects by measurements of electrical parameters of the material. Under doping of HgCdTe with arsenic using high temperature cracking, the As2 dimers are present in the arsenic flow and block the neutral Te nanocomplexes to form donor As2Te3 complexes. The results of electrical studies are compared with the results of studies carried out by micro-Raman spectroscopy.

  7. Determination of a natural valence-band offset - The case of HgTe and CdTe

    Science.gov (United States)

    Shih, C. K.; Spicer, W. E.

    1987-01-01

    A method to determine a natural valence-band offset (NVBO), i.e., the change in the valence-band maximum energy which is intrinsic to the bulk band structures of semiconductors is proposed. The HgTe-CdTe system is used as an example in which it is found that the valence-band maximum of HgTe lies 0.35 + or - 0.06 eV above that of CdTe. The NVBO of 0.35 eV is in good agreement with the X-ray photoemission spectroscopy measurement of the heterojunction offset. The procedure to determine the NVBO between semiconductors, and its implication on the heterojunction band lineup and the electronic structures of semiconductor alloys, are discussed.

  8. Analysis of whole human blood for Pb, Cd, Hg, Se, and Mn by ICP-DRC-MS for biomonitoring and acute exposures.

    Science.gov (United States)

    Jones, Deanna R; Jarrett, Jeffery M; Tevis, Denise S; Franklin, Melanie; Mullinix, Neva J; Wallon, Kristen L; Derrick Quarles, C; Caldwell, Kathleen L; Jones, Robert L

    2017-01-01

    We improved our inductively coupled plasma mass spectrometry (ICP-MS) whole blood method [1] for determination of lead (Pb), cadmium (Cd), and mercury (Hg) by including manganese (Mn) and selenium (Se), and expanding the calibration range of all analytes. The method is validated on a PerkinElmer (PE) ELAN® DRC II ICP-MS (ICP-DRC-MS) and uses the Dynamic Reaction Cell (DRC) technology to attenuate interfering background ion signals via ion-molecule reactions. Methane gas (CH4) eliminates background signal from (40)Ar2(+) to permit determination of (80)Se(+), and oxygen gas (O2) eliminates several polyatomic interferences (e.g. (40)Ar(15)N(+), (54)Fe(1)H(+)) on (55)Mn(+). Hg sensitivity in DRC mode is a factor of two higher than vented mode when measured under the same DRC conditions as Mn due to collisional focusing of the ion beam. To compensate for the expanded method's longer analysis time (due to DRC mode pause delays), we implemented an SC4-FAST autosampler (ESI Scientific, Omaha, NE), which vacuum loads the sample onto a loop, to keep the sample-to-sample measurement time to less than 5min, allowing for preparation and analysis of 60 samples in an 8-h work shift. The longer analysis time also resulted in faster breakdown of the hydrocarbon oil in the interface roughing pump. The replacement of the standard roughing pump with a pump using a fluorinated lubricant, Fomblin®, extended the time between pump maintenance. We optimized the diluent and rinse solution components to reduce carryover from high concentration samples and prevent the formation of precipitates. We performed a robust calculation to determine the following limits of detection (LOD) in whole blood: 0.07µgdL(-1) for Pb, 0.10µgL(-1) for Cd, 0.28μgL(-1) for Hg, 0.99µgL(-1) for Mn, and 24.5µgL(-1) for Se.

  9. Temperature dependence of Hg{sub 0.68}Cd{sub 0.32}Te infrared photoconductor performance

    Energy Technology Data Exchange (ETDEWEB)

    Siliquini, J.F.; Musca, C.A.; Nener, B.D.; Faraone, L. [Univ. of Western Australia, Nedlands, Western Australia (Australia). Dept. of Electrical and Electronic Engineering

    1995-08-01

    An experimental and theoretical study has been carried out of the temperature dependent noise and responsivity performance of n-type x = 0.32 Hg{sub 1{minus}x}Cd{sub x}Te photoconductors. The fundamental noise sources that ultimately limit the specific detectivity, D*{sub {lambda}}, at the three main temperatures of interest are identified and correlated with the experimental material parameters of the device. A device model is presented for the responsivity and noise voltage which takes into account surface effects such as surface recombination and accumulation layer shunting. For a given set of device and material parameters this model is well able to account for the observed experimental values of responsivity and noise voltage over the full temperature range from 80--300 K. Using a theoretical model, it is shown that under ideal conditions it is possible to achieve background limited performance at temperatures up to 210 K. Experimental results are presented for responsivity, noise voltage, semiconductor surface charge density and D*{sub {lambda}} for a frontside-illuminated Hg{sub 1{minus}x} Cd{sub x} Te photoconductive detector, as a function of temperature in the range 80--300 K. The devices were fabricated on Liquid Phase Epitaxially (LPE) grown n-type Hg{sub 0.68}Cd{sub 0.32}Te, and were passivated with anodic oxide/ZnS on the front side.

  10. Density, Electrical Conductivity and Viscosity of Hg(sub 0.8)Cd(sub 0.2)Te Melt

    Science.gov (United States)

    Li, C.; Scripa, R. N.; Ban, H.; Lin, B.; Su, C.-H.; Lehoczky, S. L.

    2004-01-01

    The density, viscosity, and electrical conductivity of Hg(sub 0.8)Cd(sub 0.2)Te melt were measures as a function of temperature. A pycnometric method was used to measure the melt density in the temperature range of 1072 to 1122 K. The viscosity and electrical conductivity were determined using a transient torque method from 1068 to 1132 K. The density result from this study is within 0.3% of the published data. However, the current viscosity result is approximately 30% lower than the existing data. The electrical conductivity of Hg(sub 0.8)Cd(sub 0.2)Te melt as a function of temperature, which is not available in the literature, is also determined. The analysis of the temperature dependent electrical conductivity and the relationship between the kinematic viscosity and density indicated that the structure of the melt appeared to be homogeneous when the temperature was above 1090 K. A structural transition occurred in the Hg(sub 0.8)Cd(sub 0.2)Te melt as the temperature was decreased to below 1090 K.

  11. Synthesis and Cell Imaging of a Near-Infrared Fluorescent Magnetic "CdHgTe-Dextran-Magnetic Layered Double Hydroxide-Fluorouracil" Composite.

    Science.gov (United States)

    Jin, XueQin; Zhang, Min; Gou, GuoJing; Ren, Jie

    2016-05-01

    In this article, a water-soluble near-infrared quantum dots of CdHgTe were prepared and subsequently combined with the drug delivery system "dextran-magnetic layered double hydroxide-fluorouracil" (DMF) to build a new nanostructure platform in form of CdHgTe@DMF, in which the fluorescent probe function of quantum dots and the magnetic targeting transport and slow-release curative effect of DMF were blended availably together. The luminescent property particle size, and internal structure of the composite were characterized using fluorescence spectrophotometer, ultraviolet spectrophotometer, laser particle size distribution, TEM, X-ray diffraction, and Fourier transform infrared. The experimental study on fluorescent tags effect and magnetic targeting performance of the multifunctional platform were performed by fluorescent confocal imaging. The results showed that the CdHgTe could be grafted successfully onto the surface of DMF by electrostatic coupling. The CdHgTe@DMF composite showed super-paramagnetic and photoluminescence property in the near-infrared wavelength range of 575-780 nm. Compared with CdHgTe, the CdHgTe@DMF composite could significantly improve the cell imaging effect, the label intensity increased with the magnetic field intensity, and obeyed the linear relationship Dmean = 1.758 + 0.0075M under the conditions of magnetic field interference. It can be implied that the CdHgTe@DMF may be an effective multifunction tool applying to optical bioimaging and magnetic targeted therapy.

  12. Effect of biochars and microorganisms on cadmium accumulation in rice grains grown in Cd-contaminated soil.

    Science.gov (United States)

    Suksabye, Parinda; Pimthong, Apinya; Dhurakit, Prapai; Mekvichitsaeng, Phenjun; Thiravetyan, Paitip

    2016-01-01

    Cadmium (Cd) contaminated in rice grains is a serious problem because most Asians consume rice on a daily basis. Rice grown in Cd-contaminated soil normally did not have high concentration of Cd. However, soil samples used in this study had high concentrations of Cd. The purpose of this study was to clearly see the effects of biochar and microorganism addition in rice growing in Cd-contaminated soil. The initial Cd concentration in Cd-contaminated soil used in this study was about 650 mg kg(-1). Cadmium concentration in rice plants grown in Cd-contaminated soil with the addition of 1% (w/w) different biochars such as sawdust fly ash (SDFA), bagasse fly ash (BGFA), and rice husk ash (RHA) was investigated. The results showed that SDFA was the best biochar in terms of reducing cadmium accumulation in rice grains when compared to BGFA and RHA under the same conditions. In addition, rice plants grown in Cd-contaminated soil with the addition of various nonpathogenic microorganisms, such as Pseudomonas aeruginosa, Bacillus subtilis, and Beauveria bassiana were also studied. The results showed that the addition of 2% (v/v) microorganisms can reduce Cd accumulation in grains. It was found that grains obtained from Cd-contaminated soil with the addition of P. aeruginosa had the lowest cadmium concentration compared to the ones from soil amended with other strains. This was due to the fact that P. aeruginosa adsorbed more Cd itself into its cells than other strains. The rice plants grown in Cd-contaminated soil with the addition of biochars and microorganisms were also compared. The results showed that adding 2% (v/v) microorganisms seemed to reduce Cd accumulation in rice grains better than adding 1% (w/w) biochars. In addition, the amounts of calcium and magnesium in rice grains and the dry weight of plant in Cd-contaminated soil amended with P. aeruginosa were the highest in comparison to other microorganisms, biochars, and the soil without any amendments (Cd

  13. Temporal trends of Cd, Cu, Hg, Pb and Zn in mussel (Mytilus galloprovincialis) from the Spanish North-Atlantic coast 1991-1999.

    Science.gov (United States)

    Besada, V; Fumega, J; Vaamonde, A

    2002-04-15

    Temporal trends for heavy metals (Cd, Cu, Hg, Pb and Zn) in mussel (Mytilus galloprovincialis) from the Galician and Cantabrian areas in Spain, where samples were yearly collected from 1991 to 1999, are presented. This study was carried out by the Centro Oceanográfico de Vigo of the Instituto Español de Oceanografia (I.E.O.) as part of the Spanish contribution to the Joint Assessment and Monitoring Programme (JAMP) of the OSPAR Convention. The experimental work and subsequent statistical treatment, following OSPAR procedures and guidelines, are described. In order to carry out the statistical treatment of the data, median values of the different shell length classes were used for each contaminant, year and area. The Kendall T-b correlation coefficient was used with the purpose of demonstrating the existence of a downward significant temporal trend in the pollution levels, according to the advice of ICES Working Group on Statistical Aspects of Environmental Monitoring. A decrease of copper levels was detected in Vigo, Pontevedra and Arosa, of mercury in Pontevedra and A Coruña, of lead in Vigo, Pontevedra, A Coruña and Bilbao and of zinc in Pontevedra and A Coruña. However, a cadmium positive trend was registered at Ria de Vigo. No significant trends were detected in the other cases.

  14. Hg 1- xCd xTe (0 ≦ x ≦ 1): a correlation between stoichiometry, surface preparation and electroreflectance measurements

    Science.gov (United States)

    Lemasson, Philippe; Van Huong, Chau Nguyen

    1990-11-01

    Mercury cadmium telluride (HCT) alloys are studied in the whole composition range by electrochemistry and electroreflectance (ER). For Hg 1- xCd xTe with 0 ≦ x ≦ 0.5 and x = 1, fairly well-defined ER structures are easily obtained using a simple pro The alloy surface is mechanically polished (0.5 μm), chemically etched in 1% bromine in methanol solution and then prepared electrochemically by cyclic voltammetry. On the other hand, ER measurements for x = 0.7 are possible only if the HCT sample is, in addition, treated specifically by means of a large amplitude AC perturbation (1 V rms, 15 Hz) for 1 to 5 min while the mean current is kept approximately zero. The electrochemical processes involved in the alloy surface preparation are analyzed in terms of a decomposition which leads to soluble species. In the whole composition range, ER spectra can be fairly well interpreted using classical methods. Energy values obtained, in particular for the E1 band-band transition, correspond exactly to what is expected on the basis of the composition of the bulk material. Therefore, electrochemistry and electroreflectance appear to be complementary techniques for the preparation and characterization of HCT alloy surfaces.

  15. Temperature Control of Mid-wave HgCdTe Thin Films Grown by MBE%MBE生长中波HgCdTe薄膜材料温度控制

    Institute of Scientific and Technical Information of China (English)

    李艳辉; 王善力; 宋立媛; 孔金丞; 赵俊; 张筱丹; 唐利斌; 姬荣斌

    2007-01-01

    报道在品格失配GaAs衬底上分子束外延CdTe缓冲层和中波HgCdTe薄膜的温度控制过程.通过红外测温仪监测样品表面温度,来改变加热功率,从而把温度控制在需要的生长温度范围.通过此方法,可以把CdTe生长时样品的表面温度控制在±5℃,MCT生长时可以达到±1℃.生长得到的样品,表面光亮,组分、厚度均匀性好,X射线双晶回摆曲线半峰宽为72 arcsec.

  16. THE CONTENT OF Cd, Pb AND Hg IN THE GRAIN OF MAIZE (ZEA MAYS L. HARVESTED IN THE ALLUVIAL SOILS OF THE UPPER REACHES OF THE RIVER NITRA

    Directory of Open Access Journals (Sweden)

    Radovan Stanovič

    2015-02-01

    Full Text Available The region of Upper Nitra has been influenced for several decades by the intensive activity of the industry. The Nitra is a river with the most polluted water ecosystems. It was caused by anthropogenic activities in the past decades. In the upper reaches of the river in the cadastral territory of the village Zemianske Kostoľany is located the thermal power plant. There is the sedimentation reservoir, which caused the ecological disaster in 1965. During this accident there was a bursting of the dam and the downstream sedimentation of sludge spill, which contaminated the entire water catchment area of the Nitra river. As a result of an ecological accident occurred to a long-term contamination of the stream but also the adjacent alluvial areas by heavy metals (Hg, As, Pb and others. In the present work, we have focused on ascertaining the level of contamination the adjacent plot of land and seeds of corn in the cadastral territory of Malé Kršteňany. We ascertained the excess of the limit values in the case of Hg on the south side of the agricultural land in Malé Kršteňany, which borders with the stream of the river. The Cd content has exceeded the limit value at the five sampling places, in the case of lead, content does not exceed the limit value. The average mercury concentration in the grain of maize was 0.095 mg.kg-1, which exceeds the limit value by 90.5%. The average cadmium content in maize grain reached the value of 0.06 mg.kg-1. This value does not exceed the limit value. Average lead accumulation in the grain of maize was 0.54 mg.kg-1, which exceeds 2.7 times the limit value. The results of analyzes indicate an increased level of land contamination by mercury and cadmium, which was reflected in an increased level of contamination by monitored metals of crops.

  17. Advanced methods for preparation and characterization of infrared detector materials. [crystallization and phase diagrams of Hg sub 1-x Cd sub x Te

    Science.gov (United States)

    Lehoczy, S. L.

    1979-01-01

    Crystal growth of Hg sub 1-x Cd sub x Te and density measurements of ingot slices are discussed. Radial compositional variations are evaluated from the results of infrared transmission edge mapping. The pseudo-binary HgTe-CdTe phase diagram is examined with reference to differential thermal analysis measurements. The phase equilibria calculations, based on the 'regular association solution' theory (R.A.S.) are explained and, using the obtained R.A.S. parameters, the activities of Hg, Cd, and Te vapors and their partial pressures over the pseudo-binary melt are calculated.

  18. Receiver Performance of CO2 and CH4 Lidar with Low Noise HgCdTe Avalanche Photodiodes

    Science.gov (United States)

    Sun, X.; Abshire, J. B.

    2012-12-01

    NASA Goddard Space Flight Center (GSFC) is currently developing CO2 lidars at 1.57 μm wavelength for the Active Sensing of CO2 Emission over Days, Nights, and Seasons (ASCENDS) mission. One of the major technical challenges is the photodetectors that have to operate in short wave infrared (SWIR) wavelength region and sensitive to received laser pulses of only a few photons. We have been using InGaAs photocathode photomultiplier tubes (PMT) in our airborne simulator of the CO2 lidar that can detect single photon with up to 10% quantum efficiency at photodetector for our CO2 lidars. The new HgCdTe APDs have typically a >50% quantum efficiency, including the effect of fill-factor, from 0.9 to 4.5 μm wavelength. DRS RSTA will integrate a low noise read-out integrated circuit (ROIC) with the HgCdTe APD array into a low noise analog SWIR detector with near single photon sensitivity. The new HgCdTe APD SWIR detector assembly is expected to improve the receiver sensitivity of our CO2 lidar by at least a factor of two and provide a sufficient wide signal dynamic range. The new SWIR detector systems can also be used in the CH4 lidars at 1.65 μm wavelength currently being developed at GSFC. The near infrared PMTs have diminishing quantum efficiency as the wavelength exceeds 1.6 μm. InGaAs APDs have a high quantum efficiency but too high an excess noise factor to achieve near quantum limited performance. The new HgCdTe APDs is expected to give a much superior performance than the PMTs and the InGaAs APDs. In this paper, we will give a brief description of the new HgCdTe APD assembly and present a receiver performance analysis of our CO2 lidar and a CH4 lidar with the new detector system in comparison to the near infrared PMTs and InGaAs APDs.

  19. Indirect exchange interaction between magnetic impurities in the two-dimensional topological insulator based on CdTe/HgTe/CdTe quantum wells

    Science.gov (United States)

    Kurilovich, P. D.; Kurilovich, V. D.; Burmistrov, I. S.

    2016-10-01

    We study indirect exchange interaction between magnetic impurities in the (001) CdTe/HgTe/CdTe symmetric quantum well. We consider low temperatures and the case of the chemical potential placed in the energy gap of the two-dimensional quasiparticle spectrum. We find that the indirect exchange interaction is suppressed exponentially with the distance between magnetic impurities. The presence of inversion asymmetry results in oscillations of the indirect exchange interaction with the distance and generates additional terms which are noninvariant under rotations in the (001) plane. The indirect exchange interaction matrix has complicated structure with some terms proportional to the sign of the energy gap.

  20. Tris(2-mercaptoimidazolyl)hydroborato Cadmium Thiolate Complexes, [Tm(Bu(t))]CdSAr: Thiolate Exchange at Cadmium in a Sulfur-Rich Coordination Environment.

    Science.gov (United States)

    Kreider-Mueller, Ava; Quinlivan, Patrick J; Owen, Jonathan S; Parkin, Gerard

    2017-04-17

    A series of cadmium thiolate compounds that feature a sulfur-rich coordination environment, namely [Tm(Bu(t))]CdSAr, have been synthesized by the reactions of [Tm(Bu(t))]CdMe with ArSH (Ar = C6H4-4-F, C6H4-4-Bu(t), C6H4-4-OMe, and C6H4-3-OMe). In addition, the pyridine-2-thiolate and pyridine-2-selenolate derivatives, [Tm(Bu(t))]CdSPy and [Tm(Bu(t))]CdSePy have been obtained via the respective reactions of [Tm(Bu(t))]CdMe with pyridine-2-thione and pyridine-2-selone. The molecular structures of [Tm(Bu(t))]CdSAr and [Tm(Bu(t))]CdEPy (E = S or Se) have been determined by X-ray diffraction and demonstrate that, in each case, the [CdS4] motif is distorted tetrahedral and approaches a trigonal monopyramidal geometry in which the thiolate ligand adopts an equatorial position; [Tm(Bu(t))]CdSPy and [Tm(Bu(t))]CdSePy, however, exhibit an additional long-range interaction with the pyridyl nitrogen atoms. The ability of the thiolate ligands to participate in exchange was probed by (1)H and (19)F nuclear magnetic resonance (NMR) spectroscopic studies of the reactions of [Tm(Bu(t))]CdSC6H4-4-F with ArSH (Ar = C6H4-4-Bu(t) or C6H4-4-OMe), which demonstrate that (i) exchange is facile and (ii) coordination of thiolate to cadmium is most favored for the p-fluorophenyl derivative. Furthermore, a two-dimensional EXSY experiment involving [Tm(Bu(t))]CdSC6H4-4-F and 4-fluorothiophenol demonstrates that degenerate thiolate ligand exchange is also facile on the NMR time scale.

  1. AKUMULASI CADMIUM (CD PADA IKAN WADER MERAH (PUNTIUS BRAMOIDES C.V, DI SUNGAI KALIGARANG

    Directory of Open Access Journals (Sweden)

    R. Prabowo

    2016-11-01

    Full Text Available Kadmium merupakan bahan beracun yang menyebabkan keracunan kronik pada manusia, maka tingkat maksimun yang diperbolehkan di perairan adalah 0,01 mg/L (PP No 82 Th 2001 Tentang Kualitas Air. Penelitian ini bertujuan (1 mengidentifikasi gambaran umum kualitas air Sungai Kaligarang, (2 Mengidentifikasi konsentrasi logam berat Kadmium (Cd di Sungai Kaligarang, serta (3 mengidentifikasi akumulasi logam berat Cd pada ikan wader merah (Puntius bramoides C.V yang hidup di Sungai Kaligarang. Penelitian ini merupakan penelitian observasi eksploratif dengan pendekatan kuantitatif yang bertujuan untuk menggambarkan kandungan logam berat Cd pada air dan ikan wader merah di Sungai Kaligarang. Penentuan lokasi pengambilan sampel secara purposif sampling. Hasil penelitian menunjukkan bahwa parameter lingkungan berupa Suhu, pH, BOD, DO di Sungai Kaligarang tidak melebihi baku mutu berdasarkan mutu air penggolongan kelas I. Parameter logam berat Cd dalam air tidak melebihi aturan yang ditetapkan PP Nomor 82 Th 2001 tentang Pengelolaan Kualitas Air dan Pengendalian Pencemaran Air. Kadar logam berat yang terkandung pada ikan wader merah masih berada di bawah baku mutu yang ditetapkan baik dari FDR New Zealand, FAO, Serta SNI. 7387.2009, Tentang Batas Maksimum Cemaran logam Berat Dalam Pangan.Cadmium is a toxic substance that causes chronic poisoning in humans and the maximum permissible level in the water is 0.01 mg / L. (Th Government Regulation No. 82 of 2001 on water quality. This study aimes to (1 identify general description of Kaligarang water quality, (2 heavy metalconcentrations of Cadmium (Cd in Kaligarang river and (3 identifying Cd accumulation of heavy metal in red Wader fish. This research is an observational exploration with a quantitative approach that aims to describe the level of heavy metal Cd in water and wader in Kaligarang. The location is determined by sampling study with purposive sampling. The result shows that the environmental parameters

  2. Influence of infrared radiation on the electrical characteristics of the surface-barrier nanostructures based on MBE HgCdTe

    Science.gov (United States)

    Pociask-Bialy, Malgorzata; Izhnin, Ihor; Voitsekhovskii, Alexander; Nesmelov, Sergey; Dzyadukh, Stanislav

    2016-12-01

    Impact of illumination on the admittance of the MIS structures based on MBE Hg1-xCdxTe with graded-gap layers and single quantum wells was investigated. It is shown that for HgCdTe-based nanostructures the illumination greatly affects the capacitance and conductance dependencies. The capacitance-voltage characteristics exhibit a low-frequency behavior, which is associated with a decrease in the differential resistance of the space charge region. Especially informative illumination exposure is in the study of deep traps in n-HgCdTe (x=0.21-0.23) without graded-gap layer. Illumination leads to the low-frequency behavior of capacitance-voltage characteristics of MIS structures based on p-HgCdTe with HgTe single quantum well in the active region, and maximums in the voltage dependences do not appear.

  3. Critical loads of Cadmium, Lead and Mercury and their exceedances in Europe

    NARCIS (Netherlands)

    Hettelingh, J.P.; Schutze, G.; Vries, W. de; Denier van der Gon, H.A.C.; Ilyin, I.; Reinds, G.J.; Slootweg, J.; Travnikov, O.

    2015-01-01

    Cadmium (Cd), lead (Pb) and mercury (Hg) are known to be transported over relatively long distances from their sources. Deposited metals may accumulate over time in soils and catchments, and then follow varying pathways to endpoints in humans and the environment. Cadmium and lead, that are emitted p

  4. Low-Cost Lattice Matching Si Based Composite Substrates for HgCdTe

    Science.gov (United States)

    2013-09-01

    211). ..............................................5 Figure 3. Relationship between calculated alloy compositions based on Se/CdTe BEP ratio and...Se:CdTe beam equivalent pressure ( BEP ) ratios. During CdSeTe growth, Se and Te are in competition for the same nucleation sites. If we assume that all...therefore, x(cal) = ΦSe/ΦCd = 2ΦSe/ΦCdTe, where Φ is the BEP of the material, measured by the nude ion gauge at the substrate position. Figure 3 shows the

  5. Cadmium sulfate and CdTe-quantum dots alter DNA repair in zebrafish (Danio rerio) liver cells

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Song; Cai, Qingsong [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States); Chibli, Hicham [Department of Biomedical Engineering, McGill University, Montréal, QC H3A 2B4 (Canada); Allagadda, Vinay [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States); Nadeau, Jay L. [Department of Biomedical Engineering, McGill University, Montréal, QC H3A 2B4 (Canada); Mayer, Gregory D., E-mail: greg.mayer@ttu.edu [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States)

    2013-10-15

    Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24 h of CdSO{sub 4} or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks. Measured levels of stress defense and DNA repair genes were elevated in both cases. However, removal of bulky DNA adducts by nucleotide excision repair (NER) was inhibited with CdSO{sub 4} but not with CdTe QDs. The adverse effects caused by acute exposure of CdTe QDs might be mediated through differing mechanisms than those resulting from ionic cadmium toxicity, and studying the effects of metallic components may be not enough to explain QD toxicities in aquatic organisms. - Highlights: • Both CdSO{sub 4} and CdTe QDs lead to cell death and Cd accumulation. • Both CdSO{sub 4} and CdTe QDs induce cellular ROS generation and DNA strand breaks. • Both CdSO{sub 4} and CdTe QDs induce the expressions of stress defense and DNA repair genes. • NER repair capacity was inhibited with CdSO{sub 4} but not with CdTe QDs.

  6. Active Pixel HgCdTe Detectors With Built-in Dark Current Reduction for Near-Room Temperature Operation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High sensitivity HgCdTe infrared arrays operating at 77K can now be tailored in a wide range of wavelengths from 1 to 14 microns. However, due to the cooling...

  7. Active Pixel HgCdTe Detectors With Built-in Dark Current Reduction for Near-Room Temperature Operation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High sensitivity HgCdTe infrared arrays operating at 77K can now be tailored in a wide range of wavelengths from 1 to14 um. However, the cooling requirements make...

  8. The average concentrations of As, Cd, Cr, Hg, Ni and Pb in residential soil and drinking water obtained from springs and wells in Rosia Montana area.

    Data.gov (United States)

    U.S. Environmental Protection Agency — The average concentrations of As, Cd, Cr, Hg, Ni and Pb in n=84 residential soil samples, in Rosia Montana area, analyzed by X-ray fluorescence spectrometry are...

  9. Experimental analysis of the simultaneous uptake of the heavy metals Cd, Hg, Pb, Cu, Zn, Se in the sporophore of mushrooms. Versuche ueber die simultane Aufnahme der Schwermetalle Cd, Hg, Pb, Cu, Zn und Se in Pilzfruchtkoerper

    Energy Technology Data Exchange (ETDEWEB)

    Suehs, K.

    With mushrooms of the species Agaricus bisporus and Boletus badius the simultaneous uptake of the heavy metals Cd, Hg, Pb, Cu, Zn, and Se from soil to the sporophore was studied. To avoid misleadingly overrated enrichmentfactors when comparing the heavy metal contents of dried mushrooms and soils, a so-called transfer factor TF[sub v] which is related to the volume is put to discussion here, this factor takes account of the relatively small amount of dry matter in mushrooms and of the different composition (that means specific weight) of the soils in question. With help of these transfer factors the conclusion is derived, that essential elements show a better enrichment behaviour than biologically superfluous heavy metals, at least this is true with the insignificantly contaminated soils we investigated. With Cd as an example of a ''superfluous'' element it is shown that there is a strict proportionality of Cd concentrations in the mushrooms and the corresponding soils, thus producing a constant transfer factor. Apart from this the uptake of copper into the mushrooms is promoted (growth of the transfer factor) by a larger Cd supply, whereas the other elements under investigation (even the classical antagonist Zn) are not significantly affected. Furthermore there is evidence that with increasing heavy metal concentration (Cd) first the fructification of the thallus is supported and moreover, that increasing age of this primary fungus corresponds with an increase of heavy metals in the mushrooms. (orig.)

  10. Assessment of Individual and Combined Toxicities of Four Non-Essential Metals (As, Cd, Hg and Pb in the Microtox Assay

    Directory of Open Access Journals (Sweden)

    Paul B. Tchounwou

    2006-03-01

    Full Text Available Although most researches with non-essential metals (NEMs have been done with single or individual metals, in reality, organisms are often exposed to multiple contaminants at the same time through the air, food and water. In this study, we tested the toxicity of four NEMs, As, Cd, Pb, and Hg, individually and as a composite mixture using the microtox bioassay. This assay uses the reduction of bioluminescence of the bacterium Vibrio fischeri as a measure of toxicity. The concentrations of each chemical in the mixture were based on multiples of their maximum contaminant levels (MCLs set by the U.S. EPA. The highest concentration of exposure was 20 times the MCL, which translated into 200, 100, 40 and 300 ppb for As, Cd, Hg and Pb, respectively. The ratio for the mixture from these concentrations was 10:5:2:15 for As, Cd, Hg and Pb, respectively. Among the individual metals tested, the ranking of toxicity was Hg>Pb>Cd>As based on the EC50 values of 109, 455, 508 and 768 ppb for Hg, Pb, Cd and As, respectively. The EC50 for the composite mixture was 495% MCL which translated into nominal concentrations of 49, 25, 10 and 74 ppb for As, Cd, Hg, and Pb, respectively. Overall, the EC50 value of each NEM within the mixture was lower than the EC50 of the individual chemical; an evidence of synergism for the mixture. The individual toxic units (TU were 0.06, 0.05, 0.09, and 0.16 for As, Cd Hg, and Pb, respectively and the summed toxic unit (TU was 0.37 (less than 1. This study provides needed scientific data necessary for carrying out complete risk assessment of As, Cd, Hg, and Pb mixtures of some priority compounds.

  11. Absorption Reduction Capacity with Chromium (Cr and Cadmium (Cd Contaminants of Vetiver Phytoremediation Process on Compost Soil

    Directory of Open Access Journals (Sweden)

    Ahamad Zubair

    2016-01-01

    Full Text Available This study aims to analyze the large of reduction capacity of chromium metals and cadmium in the soil compost media and absorption capacity of chrome and cadmium in phytoremediation process of vetiver; to compare the reduction-absorption capacities of chromium and cadmium metals in phytoremediation process of vetiver (Vetivera zizanioides. The study was carried out for 2 months with a range of sampling every 7 days, and then analyzed by using Atomic Absorption Spectrophotometer (AAS. Contaminants used as artificial contaminants containing heavy metals chromium (Cr and cadmium (Cd. This study is an experimental research includes two variables. First, the variations of Cr concentrations used were 400 ppm, 600 ppm and 800 ppm and Cd concentrations used were 40 ppm, 60 ppm, 800 ppm. Secondly, the variations of total plant are 3, 6, and 9 plant. The period of observation is made every week. Planting media used is compost soil with compost and clay composition of 20%, 30% and 40%. The results of study showed that there are a significant relationship between the reduction capacity of Cr and Cd of compost soil and the absorption capacity of Cr and Cd for vetiver (Vetiveria zizanioides. The higher of Cr and Cd decreases in soil followed by increased levels of Cr and Cd in vetiver (Vetiveria zizanioides. The capacity of Cr reduction varies between 57% - 86% and Cd 36% - 64% where as the absorption capacity of vetiver on Cr between 38% - 75% and Cd between 34%-74%. The capacity of reduction-absorption of Cr is relatively higher than Cd in phytoremediation process of vetiver.

  12. Hole Transport in Arsenic-Doped Hg1- x Cd x Te with x ≥ 0.5

    Science.gov (United States)

    Umana-Membreno, G. A.; Kala, H.; Bains, S.; Akhavan, N. D.; Antoszewski, J.; Maxey, C. D.; Faraone, L.

    2016-09-01

    Hole transport in arsenic-doped p-type Hg1- x Cd x Te epitaxial layers with x ≥ 0.5 has been studied employing Hall-effect measurements and theoretical modeling of hole scattering mechanisms. The hole transport parameters extracted from four different Hg1- x Cd x Te films with x = 0.50, 0.56-0.58, 0.65, and 0.80, were analyzed using an iterative solution of Boltzmann's transport equation. Hole mobilities in the samples with x values of 0.5 and 0.56-0.58 were found to be predominantly limited by ionized impurity scattering, and exhibited relatively high impurity compensation ratios ≥2. The sample with x = 0.65 exhibited the highest hole mobility, a low compensation ratio of 1.05, and mobility characteristics were limited predominantly by polar optical phonon scattering at temperatures ≥200 K. Hole mobility in the sample with x = 0.80 was found to be limited by polar optical phonon scattering and ionized impurity scattering (compensation ratio 1.20-1.56). Although the sample temperatures employed were not sufficiently low to unambiguously discriminate the scattering strength of static strain and dislocations, the experimental hole mobility characteristics cannot be adequately modeled if these two mechanisms are neglected. The ionization energy of the arsenic acceptor impurities was found to exhibit a quadratic dependence on the CdTe mole fraction.

  13. Development of High-Performance eSWIR HgCdTe-Based Focal-Plane Arrays on Silicon Substrates

    Science.gov (United States)

    Park, J. H.; Pepping, J.; Mukhortova, A.; Ketharanathan, S.; Kodama, R.; Zhao, J.; Hansel, D.; Velicu, S.; Aqariden, F.

    2016-09-01

    We report the development of high-performance and low-cost extended short-wavelength infrared (eSWIR) focal-plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates. High-quality n-type eSWIR HgCdTe (cutoff wavelength ˜2.68 μm at 77 K, electron carrier concentration 5.82 × 1015 cm-3) layers were grown on CdTe/Si substrates by MBE. High degrees of uniformity in composition and thickness were demonstrated over three-inch areas, and low surface defect densities (voids 9.56 × 101 cm-2, micro-defects 1.67 × 103 cm-2) were measured. This material was used to fabricate 320 × 256 format, 30 μm pitch FPAs with a planar device architecture using arsenic implantation to achieve p-type doping. The dark current density of test devices showed good uniformity between 190 K and room temperature, and high-quality eSWIR imaging from hybridized FPAs was obtained with a median dark current density of 2.63 × 10-7 A/cm2 at 193 K with a standard deviation of 1.67 × 10-7 A/cm2.

  14. Cadmium(II) complex formation with selenourea and thiourea in solution: an XAS and 113Cd NMR study.

    Science.gov (United States)

    Jalilehvand, Farideh; Amini, Zahra; Parmar, Karnjit

    2012-10-15

    The complexes formed in methanol solutions of Cd(CF(3)SO(3))(2) with selenourea (SeU) or thiourea (TU), for thiourea also in aqueous solution, were studied by combining (113)Cd NMR and X-ray absorption spectroscopy. At low temperature (~200 K), distinct (113)Cd NMR signals were observed, corresponding to CdL(n)(2+) species (n = 0-4, L = TU or SeU) in slow ligand exchange. Peak integrals were used to obtain the speciation in the methanol solutions, allowing stability constants to be estimated. For cadmium(II) complexes with thione (C═S) or selone (C═Se) groups coordinated in Cd(S/Se)O(5) or Cd(S/Se)(2)O(4) (O from MeOH or CF(3)SO(3)(-)) environments, the (113)Cd chemical shifts were quite similar, within 93-97 ppm and 189-193 ppm, respectively. However, the difference in the chemical shift for the Cd(SeU)(4)(2+) (578 pm) and Cd(TU)(4)(2+) (526 ppm) species, with CdSe(4) and CdS(4) coordination, respectively, shows less chemical shielding for the coordinated Se atoms than for S, in contrast to the common trend with increasing shielding in the following order: O > N > Se > S. In solutions dominated by mono- and tetra-thiourea/selenourea complexes, their coordination and bond distances could be evaluated by Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. At ~200 K and high excess of thiourea, a minor amount (up to ~30%) of [Cd(TU)(5-6)](2+) species was detected by an upfield shift of the (113)Cd NMR signal (up to 423 ppm) and an amplitude reduction of the EXAFS oscillation. The amount was estimated by fitting linear combinations of simulated EXAFS spectra for [Cd(TU)(4)](2+) and [Cd(TU)(6)](2+) complexes. At room temperature, [Cd(TU)(4)](2+) was the highest complex formed, also in aqueous solution. Cd L(3)-edge X-ray absorption near edge structure (XANES) spectra of cadmium(II) thiourea solutions in methanol were used to follow changes in the CdS(x)O(y) coordination. The correlations found from the current and previous studies between (113

  15. 分子束外延生长Hg1-χCdχTe材料原位退火研究%A Study of In Situ Annealing of MBE Growth Hg1-xCdxTe

    Institute of Scientific and Technical Information of China (English)

    苏栓; 李艳辉; 周旭昌; 杨春章; 谭英; 高丽华; 李全保

    2009-01-01

    对分子束外延(MBE)生长了Hg1-χCdχTe薄膜材料进行原位退火研究.显微镜观察可知,原位退火可以得到光滑的材料表面,并可以降低材料的腐蚀坑密度(EPD).霍尔测试结果表明,通过调整退火温度和汞束流可以明显地改善Hg1-χCdχTe材料的电学性能.研究表明Hg1-χCdχTe材料的原位退火技术在改善材料的微观结构和电学性能方面有着重要的意义.

  16. Cadmium in the waters off South Morocco: Nature of particles hosting Cd and insights into the mechanisms fractionating Cd from phosphate

    Science.gov (United States)

    Waeles, Matthieu; Planquette, Hélène; Afandi, Imane; Delebecque, Nina; Bouthir, Fatimazohra; Donval, Anne; Shelley, Rachel U.; Auger, Pierre-Amaël.; Riso, Ricardo D.; Tito de Morais, Luis

    2016-05-01

    In this study, we report the distributions of total dissolvable cadmium and particulate cadmium from 27 stations in southern Moroccan coastal waters (22°N-30°N), which is part of the North-West African upwelling system. These distributions were predominantly controlled by upwelling of the North Atlantic Central Waters (NACWs) and uptake by primary production. Atmospheric inputs and phosphogypsum slurry inputs from the phosphate industry at Jorf Lasfar (33°N), recently estimated as an important source of dissolved cadmium (240 t Cd yr-1), are at best of minor importance for the studied waters. Our study provides new insights into the mechanisms fractionating cadmium from phosphate. In the upper 30 m, the anomalies observed in terms of Cd:P ratios in both the particulate and total dissolvable fractions were related to an overall preferential uptake of phosphate. We show that the type of phytoplanktonic assemblage (diatoms versus dinoflagellates) is also a determinant of the fractionation intensity. In subsurface waters (30-60 m), a clear preferential release of P (versus Cd) was observed indicating that remineralization in Oxygen Minimum Zones is a key process in sequestering Cd.

  17. Performance of MWIR and SWIR HgCdTe-based focal plane arrays at high operating temperatures

    Science.gov (United States)

    Melkonian, Leon; Bangs, James; Elizondo, Lee; Ramey, Ron; Guerrero, Ernesto

    2010-04-01

    Raytheon Vision Systems (RVS) is producing large format, high definition HgCdTe-based MWIR and SWIR focal plane arrays (FPAs) with pitches of 15 μm and smaller for various applications. Infrared sensors fabricated from HgCdTe have several advantages when compared to those fabricated from other materials -- such as a highly tunable bandgap, high quantum efficiencies, and R0A approaching theoretical limits. It is desirable to operate infrared sensors at elevated operating temperatures in order to increase the cooler life and reduce the required system power. However, the sensitivity of many infrared sensors, including those made from HgCdTe, declines significantly above a certain temperature due to the noise resulting from increasing detector dark current. In this paper we provide performance data on a MWIR and a SWIR focal plane array operating at temperatures up to 160K and 170K, respectively. The FPAs used in the study were grown by molecular beam epitaxy (MBE) on silicon substrates, processed into a 1536x1024 format with a 15 μm pixel pitch, and hybridized to a silicon readout integrated circuit (ROIC) via indium bumps to form a sensor chip assembly (SCA). This data shows that the noise equivalent delta temperature (NEDT) is background limited at f/3.4 in the SWIR SCA (cutoff wavelength of 3.7 μm at 130K) up to 140K and in the MWIR SCA (cutoff wavelength of 4.8 μm at 115K) up to 115K.

  18. First and second harmonic generation of the XAl2Se4 (X=Zn,Cd,Hg) defect chalcopyrite compounds

    OpenAIRE

    Ouahrani, Tank; Khenata, R.; Lasri, B; Reshak, Ali H.; Bouhemadou, A.; Bin-Omran, S

    2012-01-01

    The chemical bonding of the ZnAl2Se4, CdAl2Se4 and HgAl2Se4 defect chalcopyrites has been studied in the framework of the quantum theory of atoms in molecules (AIM). The GW quasi-particle approximation is used to correct the DFT-underestimation of energy gap, and as a consequence the linear and nonlinear optical properties are significantly enhanced. The second harmonic generation (SHG) displays certain dependence with the ionicity degree decrease through the dependency of the SHG on the band...

  19. CÁLCULOS DE PRIMEIROS PRINCÍPIOS EM ISOLANTES TOPOLÓGICOS: HgTe/CdTe

    OpenAIRE

    Jonas Anversa

    2014-01-01

    A observação do efeito Spin Hall Quântico na heteroestrutura HgTe/CdTe motivou o estudo de materiais que exibem uma corrente eletrônica spin-polarizada nas suas interfaces/ superfícies. Estes estados são topologicamente protegidos frente a perturbações que preservam a simetria de reversão temporal e apresentam uma dispersão linear formando um Cone de Dirac. Entretanto, perturbações não-magnéticas (que preservam a reversão temporal) irão certamente afetar estes estados de interf...

  20. Reverse breakdown in long wavelength lateral collection Cd sub x Hg sub 1 sub minus x Te diodes

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, C.T.; Gordon, N.T.; Hall, R.S. (Royal Signals, Malvern, Worcs WR14 3PS, (England) Radar Establishment, Malvern, Worcs WR14 3PS, England (GB)); Crimes, G. (Philips Components, Southampton, Hants S09 7BH, (England))

    1990-03-01

    Long wavelength diodes in Cd{sub {ital x}}Hg{sub 1{minus}{ital x}}Te show large deviations from ideality in their reverse characteristics. The excess currents are attributed in many published papers on band to band tunneling at high reverse bias and to trap assisted tunneling at low reverse bias. Measurements of photocurrent multiplication, current--voltage characteristics, and noise have been made on long wavelength loophole diodes to determine the breakdown mechanism. This has produced strong evidence that the reverse characteristics of good quality diodes of this type are limited by impact ionization. At higher biases, there is evidence of an additional breakdown mechanism, probably tunneling.

  1. Development of HgCdSe for Third Generation Focal Plane Arrays using Molecular Beam Epitaxy

    Science.gov (United States)

    2013-08-01

    chemomechanical polishing, or CMP ), or submerging the material and applying a potential difference ( electrochemical polishing). In addition to reducing...as Nate England, Eric Schires, and Dr. Ravi Droopad their work setting up the molecular beam epitaxy growth and characterization systems for the...would like to thank Dr. Craig H. Swartz at Texas State University—San Marcos for his work on the electrical characterization of Hg1-xCdxSe, and Dr

  2. Trace elements concentrations (Zn, Cu, Pb, Cd, As and Hg in the Mediterranean mussel (Mytilus galloprovincialis and evaluation of mussel quality and possible human health risk from cultivated and wild sites of the southeastern Adriatic Sea, Montenegro

    Directory of Open Access Journals (Sweden)

    Jović Mihajlo

    2011-01-01

    Full Text Available The Mediterranean mussel Mytilus galloprovincialis (L was collected from the fall 2005 to the winter 2009 from the six sites on the Montenegrin coastline. Two wild samples were collected from the open sea coastline, and two cultivated and two wild were from the Boka Kotorska Bay. The mussels soft tissue was analyzed for zinc (Zn, copper (Cu, lead (Pb, cadmium (Cd, arsenic (As and total mercury (Hg. Concentrations of these metals ranged from 135.5-210 for Zn, 6.2-14.5 for Cu, 4.0-11.5 for Pb, 1.7-2.1 for Cd, 5.8-12.4 for As and 0.11-0.51 for Hg, in mg kg-1 dry weight. The metals were found to be present in the samples at different levels, but not in concentrations higher than maximum residual levels prescribed by the European Union (EU and US Food and Drug Administration (USFDA regulations for seafood. This indicates that the consumption of wild or cultivated mussels from the studied area is safe in moderate quantities.

  3. Electroplating of CdTe Thin Films from Cadmium Sulphate Precursor and Comparison of Layers Grown by 3-Electrode and 2-Electrode Systems

    Directory of Open Access Journals (Sweden)

    Imyhamy M. Dharmadasa

    2017-01-01

    Full Text Available Electrodeposition of CdTe thin films was carried out from the late 1970s using the cadmium sulphate precursor. The solar energy group at Sheffield Hallam University has carried out a comprehensive study of CdTe thin films electroplated using cadmium sulfate, cadmium nitrate and cadmium chloride precursors, in order to select the best electrolyte. Some of these results have been published elsewhere, and this manuscript presents the summary of the results obtained on CdTe layers grown from cadmium sulphate precursor. In addition, this research program has been exploring the ways of eliminating the reference electrode, since this is a possible source of detrimental impurities, such as K+ and Ag+ for CdS/CdTe solar cells. This paper compares the results obtained from CdTe layers grown by three-electrode (3E and two-electrode (2E systems for their material properties and performance in CdS/CdTe devices. Thin films were characterized using a wide range of analytical techniques for their structural, morphological, optical and electrical properties. These layers have also been used in device structures; glass/FTO/CdS/CdTe/Au and CdTe from both methods have produced solar cells to date with efficiencies in the region of 5%–13%. Comprehensive work carried out to date produced comparable and superior devices fabricated from materials grown using 2E system.

  4. Competing mechanism driving diverse pressure dependence of thermal conductivity of X Te (X =Hg ,Cd , and Zn)

    Science.gov (United States)

    Ouyang, Tao; Hu, Ming

    2015-12-01

    Effectively engineering the lattice thermal conductivity of materials is a key interest of the current thermal science community. Pressure or compressive strain is one of the most worthwhile processes to modify the thermal transport property of materials, due to its robust tunability and flexibility of realization. While it is well documented in the literature that the application of hydrostatic pressure normally increases the thermal conductivity of bulk materials, little work has been performed on abnormal pressure-dependent thermal conductivity and the governing mechanism has not been fully understood yet. In this paper, taking bulk telluride systems X Te (X =Hg ,Cd ,Zn ) as examples, we show, by combining first-principle calculation and the phonon Boltzmann transport equation, that the thermal conductivity presents diverse pressure dependence although they belong to the same group. The thermal conductivity of ZnTe is independent of pressure, while abnormal negative pressure dependence of thermal conductivity is observed in HgTe. As for CdTe, the trend falls in between HgTe and ZnTe and relies largely on the temperature. By comparing the key contributors of the lattice thermal conductivity, we find that the diverse pressure dependence of the lattice thermal conductivity is governed by the competition between the enhancement of group velocity of longitudinal acoustic and optic modes and the reduction of phonon relaxation time of transverse acoustic modes, with both effects being fully quantified by our calculation. Comparison with traditional bulk systems such as silicon further underpins the governing mechanism. The correlation between the diverse thermal transport phenomena and the nature of the atomic bonding is also qualitatively established. These findings are expected to deepen our understanding of manipulating phonon transport of bulk materials via simple compressive strain and are also helpful for related applications, such as optimizing thermoelectric

  5. Local structure and site occupancy of Cd and Hg substitutions in CeTIn_5 (T=Co, Rh, Ir)

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Corwin H.; Bauer, Eric. D.; Bianchi, Andrea D.; Ronning, Fillip; Thompson, Joe D.; Sarrao, John L.; Cho, Jung Young; Chan, Julia Y.; Capan, Cigdem; Fisk, Zachary

    2009-04-22

    The CeTIn_5 superconductors (T=Co, Rh, or Ir) have generated great interest due to their relatively high transition temperatures, non-Fermi liquid behavior, and their proximity to antiferromagnetic order and quantum critical points. In contrast to small changes with the T-species, electron doping in CeT(In_1-x M_x)_5 with $M$=Sn and hole doping with Cd or Hg have a dramatic effect on the electronic properties at very low concentrations. The present work reports local structure measurements usingthe extended x-ray absorption fine-structure (EXAFS) technique that address the substituent atom distribution as a function of T, M, and x, in the vicinity of the superconducting phase. Together with previous measurements for M=Sn, the proportion of the $M$ atom residing on the In(1) site, f_\\textrm In(1), increases in the order M=Cd, Sn, and Hg, ranging from about 40\\percent to 70percent, showing a strong preference for each of these substituents to occupy the In(1) site (random occupation = 20percent). In addition, f_In(1) ranges from 70percent to 100percent for M=Hg in the order T=Co,Rh, and Ir. These fractions track the changes in the atomic radii of the various species, and help explain the sharp dependence of $T_c$ on substituting into the In site. However, it is difficult to reconcile the small concentrations of M with the dramatic changes in the ground state in the hole-doped materials with only an impurity scattering model. These results therefore indicate that while such substitutions have interesting local atomic structures with important electronic and magnetic consequences, other local changes in the electronic and magnetic structure are equally important in determining the bulk properties of these materials.

  6. Local structure and site occupancy of Cd and Hg substitutions in CeTIn5 (T=Co, Rh, Ir)

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Eric D [Los Alamos National Laboratory; Ronning, Filip [Los Alamos National Laboratory; Thompson, J D [Los Alamos National Laboratory; Sarrao, J L [Los Alamos National Laboratory; Booth, C H [LBNL; Bianchi, A D [UC, IRVINE; Cho, J Y [LSU; Chan, J Y [LSU; Capan, C [UC-IRVINE; Fisk, Z [UC-IRVINE

    2009-01-01

    The CeTIn{sub 5} superconductors (T = Co, Rh, or Ir) have generated great interest due to their relatively high transition temperatures, non-Fermi liquid behavior, and their proximity to antiferromagnetic order and quantum critical points. In contrast to small changes with the T-species, electron doping in CeT(In{sub 1-x}M{sub x}){sub 5} with M = Sn and hole doping with Cd or Hg have a dramatic effect on the electronic properties at very low concentrations. The present work reports local structure measurements using the extended x-ray absorption fine-structure (EXAFS) technique that address the substituent atom distribution as a function of T, M, and x, in the vicinity of the superconducting phase. Together with previous measurements for M = Sn, the proportion of the M atom residing on the In(1) site, f{sub 1n(1)}, increases in the order M = Cd, Sn, and Hg, ranging from about 40% to 70%, showing a strong preference for each of these substituents to occupy the In(1) site (random occupation = 20%). In addition, f{sub In(1)} ranges from 70% to 100% for M = Hg in the order T = Co, Rh, and Ir. These fractions track the changes in the atomic radii of the various species, and help explain the sharp dependence of T{sub c} on substituting into the In site. However, it is difficult to reconcile the small concentrations of M with the dramatic changes in the ground state in the hole-doped materials with only an impurity scattering model. These results therefore indicate that while such substitutions have interesting local atomic structures with important electronic and magnetic consequences, other local changes in the electronic and magnetic structure are equally important in determining the bulk properties of these materials.

  7. Chalcophile elements Hg, Cd, Pb, As in Lake Umbozero, Murmansk Region, Russia

    DEFF Research Database (Denmark)

    Dauvalter, V.A.; Kashulin, N.A.; Lehto, J.;

    2009-01-01

    to higher concentrations of heavy metals in upper layers of sediments as compared to deeper layers. Among heavy metals, the highest factors of contamination were found for Cd and Pb. Pollution of the lake by chalcophile elements has also resulted in their accumulation in organs and tissues of whitefish...... is affected by emissions and effluents from mining and metallurgical enterprises of the Murmansk Region, as well as air pollution of a global character. Surface and near-bottom maxima were found in the distributions of Pb and Cd in the water column. These two maxima appear to be associated with the cyclical...... growth of phytoplankton in surface water layers and with sedimentation of lifeless organisms and suspended particles in near-bottom layers. Average concentrations of Pb and Cd in the water column were more than the average value for water of lakes of the taiga zone. Pollution of Lake Umbozero led...

  8. Extraction and isolation of the salidroside-type metabolite from zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance

    Institute of Scientific and Technical Information of China (English)

    Yan XING; Hong-yun PENG; Xia LI; Meng-xi ZHANG; Ling-ling GAO; Xiao-e YANG

    2012-01-01

    The active metabolite in the post-harvested biomass of zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance from phytoextraction is of great interest in China.The current study demonstrates that a salidroside-type metabolite can be yielded from the ZniCd hyperaccumulator S.alfredii biomass by means of sonication/ethanol extraction and macroporous resin column (AB-8 type) isolation.The concentrations of Zn and Cd in the salidroside-type metabolite were below the limitation of the national standards.

  9. Extraction and isolation of the salidroside-type metabolite from zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance*

    Science.gov (United States)

    Xing, Yan; Peng, Hong-yun; Li, Xia; Zhang, Meng-xi; Gao, Ling-ling; Yang, Xiao-e

    2012-01-01

    The active metabolite in the post-harvested biomass of zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance from phytoextraction is of great interest in China. The current study demonstrates that a salidroside-type metabolite can be yielded from the Zn/Cd hyperaccumulator S. alfredii biomass by means of sonication/ethanol extraction and macroporous resin column (AB-8 type) isolation. The concentrations of Zn and Cd in the salidroside-type metabolite were below the limitation of the national standards. PMID:23024051

  10. Synthesis and characterization of La11+xHg45-x and RE11Hg44.5 (RE = Nd, Sm) as hettotypes of the Sm11Cd45 structure type

    Science.gov (United States)

    Tambornino, Frank; Schwärzer, Kuno; Hoch, Constantin

    2016-10-01

    The mercury-rich amalgams La11+xHg45-x and RE11Hg44.5 (space group F4bar3m (No. 216), La11+xHg45-x : a = 21.9342(19) Å, RE = Nd: a = 21.7384(14) Å; RE = Sm: a = 21.6555(4) Å), were synthesized by dissolving the respective rare earth metals in a mercury surplus and subsequently distilling off the excess. The compounds were characterized by single crystal and powder X-ray methods together with ab-initio band structure calculations. Both crystal structures deviate significantly and in different ways from their common aristotype, the Sm11Cd45 structure type. In La11+xHg45-x (x = 0.7(1)) two crystallographic sites show mixed occupancy, whereas in RE11Hg44.5 one of the Hg positions is fully unoccupied. Their band structures exhibit typical broad Hg d states at low energies, and a strong mixing of s and p states indicates a mercury sublattice with high connectivity.

  11. Visible to SWIR response of HgCdTe HDVIP detectors

    Science.gov (United States)

    D'Souza, A. I.; Robinson, E. W.; Stapelbroek, M. G.; Wong, W.; Skokan, M.; Shih, H.-D.

    2009-05-01

    Detectors that have broadband response from the visible (~ 400 nm) to near infrared (~ 2.5 μm) have remote sensing hyperspectral applications on a single chip. 2.2 and 2.5 μm cutoff detectors permit operation in the 200 K range. The DRS HDVIP detector technology is a front side illuminated detector technology. Consequently, there is no substrate to absorb the visible photons as in backside-illuminated detectors and these 2.2 and 2.5-μm-cutoff detectors should be well suited to respond to visible light. However, HDVIP detectors are passivated using CdTe that absorbs the visible light photons. CdTe with a direct bandgap ~ 1.6 eV strongly absorbs photons of wavelength shorter than about 800 nm. Detectors in 320 x 6 arrays with varying thickness of CdTe passivation layers were fabricated to investigate the visible response of the 2.5-μm-cutoff detectors. The SWIR HDVIP detectors have well known high quantum efficiency (QE) in the near infrared region. Focus here was in acquiring array level data in the visible region of the spectrum. 320 x 6 FPA QE and NEI data was acquired using a 642 nm narrow band filter with 50 % points at 612 nm and 698 nm. The array QE average is ~ 70 % for the array with CdTe passivation thickness = 44.5 nm. The NEI is ~ 5 x 1010 ph/cm2/s at a flux Φ = 5.36 x 1013 ph/cm2/s. QE for an array with CdTe passivation thickness = 44.5 nm is ~ 10 % higher than an array with CdTe passivation thickness = 79.3 nm. In addition, a model that takes into account the complex optical properties of every layer in the HDVIP photodiode architecture was developed to predict the QE of the detectors in the near infrared and visible wavelength regions as a function of CdTe thickness. Measured QE as a function of wavelength is not a good match to the model QE probably due to limitations in the measured QE and knowledge of optical constants that are input into the model.

  12. Magnetic hyperfine interactions on Cd sites of the rare-earth cadmium compounds R Cd (R =Ce , Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

    Science.gov (United States)

    Cavalcante, F. H. M.; Leite Neto, O. F. L. S.; Saitovitch, H.; Cavalcante, J. T. P. D.; Carbonari, A. W.; Saxena, R. N.; Bosch-Santos, B.; Pereira, L. F. D.; Mestnik-Filho, J.; Forker, M.

    2016-08-01

    This paper reports the investigation of the magnetic hyperfine field Bh f in a series of rare-earth (R ) cadmium intermetallic compounds R Cd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using 111In/111Cd as probe nuclei at Cd sites as well as first-principles calculations of Bh f at Cd sites in the studied compounds. Vapor-solid state reaction of R metals with Cd vapor and the 111In radioisotope was found to be an appropriate route of doping rare-earth cadmium compounds with the PAC probe 111In/111Cd. The observation that the hyperfine parameters depend on details of the sample preparation provides information on the phase preference of diffusing 111In in the rare-earth cadmium phase system. The 111Cd hyperfine field has been determined in the compounds R Cd for the R constituents Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, in several cases as a function of temperature. For most R constituents, the temperature dependence Bh f(T ) of 111Cd:R Cd is consistent with ferromagnetic order of the compound. DyCd, however, presents a remarkable anomaly: a finite magnetic hyperfine field is observed only in the temperature interval 35 K ≤ T ≤ 80 K which indicates a transition from ferromagnetic order to a spin arrangement where all 4 f -induced contributions to the magnetic hyperfine field at the Cd site cancel. First-principles calculation results for DyCd show that the (π , π , 0) antiferromagnetic configuration is energetically more favorable than the ferromagnetic. The approach used in the calculations to simulate the R Cd system successfully reproduces the experimental values of Bh f at Cd sites and shows that the main contribution to Bh f comes from the valence electron polarization. The de Gennes plot of the hyperfine field Bh f of 111Cd:R Cd vs the 4 f -spin projection (g -1 )J reflects a decrease of the strength of indirect 4 f -4 f exchange across the R series. Possible mechanisms are discussed and the experimental results indicate that

  13. 中波HgCdTe光导探测器组件的故障树和失效研究%Study on HgCdTe Detector Assemble Fault Tree and Failure Analysis

    Institute of Scientific and Technical Information of China (English)

    王韡; 许金通; 周青; 张立瑶; 李向阳

    2012-01-01

    Discussed are the reliability problems of HgCdTe(MCT) infrared photoconductive detectors working at near room temperature,including package failure,chip bonding failure and performance attenuation.Based on collecting the failure data of the detectors,fault tree analysis(FTA) was built by analyzing the failure mechanism of physics and chemistry,manufacturing process and parameters of the detectors.Minimal cut sets of FTA were obtained from qualitative analysis and the failure probability of top event was calculated.The failure modes in detectors,structures and process were analyzed.%讨论了近室温工作的HgCdTe中波光导探测器组件的可靠性问题,包括组件封装失效、引线键合失效和探测器的性能衰减等。通过收集探测器组件的失效信息,对其失效物理化学机制、制造工艺和探测器参数进行了分析,建立了组件的故障树(FTA),为探测器组件的失效分析提供了理论依据。由FTA定性分析得出探测器组件FTA的最小割集;计算了顶事件的失效几率。通过计算底事件概率重要度,得出组件封装失效是探测器组件失效的主要故障途径;同时实验发现,失效组件探测器的少子寿命值有较大的衰减,这可能起源于失效探测器的表面钝化层退化。

  14. Experimental Determination of Effective Minority Carrier Lifetime in HgCdTe Photovoltaic Detectors Using Optical and Electrical Methods

    Directory of Open Access Journals (Sweden)

    Haoyang Cui

    2015-01-01

    Full Text Available This paper presents experiment measurements of minority carrier lifetime using three different methods including modified open-circuit voltage decay (PIOCVD method, small parallel resistance (SPR method, and pulse recovery technique (PRT on pn junction photodiode of the HgCdTe photodetector array. The measurements are done at the temperature of operation near 77 K. A saturation constant background light and a small resistance paralleled with the photodiode are used to minimize the influence of the effect of junction capacitance and resistance on the minority carrier lifetime extraction in the PIOCVD and SPR measurements, respectively. The minority carrier lifetime obtained using the two methods is distributed from 18 to 407 ns and from 0.7 to 110 ns for the different Cd compositions. The minority carrier lifetime extracted from the traditional PRT measurement is found in the range of 4 to 20 ns for x=0.231–0.4186. From the results, it can be concluded that the minority carrier lifetime becomes longer with the increase of Cd composition and the pixels dimensional area.

  15. Expression differences for genes involved in lignin, glutathione and sulphate metabolism in response to cadmium in Arabidopsis thaliana and the related Zn/Cd-hyperaccumulator Thlaspi caerulescens

    NARCIS (Netherlands)

    Mortel, van de J.E.; Schat, H.; Moerland, P.D.; Loren van Themaat, Ver E.; Ent, van der S.; Blankestijn-de Vries, M.H.C.; Ghandilyan, A.; Tsiatsiani, S.; Aarts, M.G.M.

    2008-01-01

    Cadmium (Cd) is a widespread, naturally occurring element present in soil, rock, water, plants and animals. Cd is a non-essential element for plants and is toxic at higher concentrations. Transcript profiles of roots of Arabidopsis thaliana (Arabidopsis) and Thlaspi caerulescens plants exposed to Cd

  16. Dielectric functions and carrier concentrations of Hg{sub 1−x}Cd{sub x}Se films determined by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A. J.; Peiris, F. C., E-mail: peirisf@kenyon.edu [Department of Physics, Kenyon College, Gambier, Ohio 43022 (United States); Brill, G.; Doyle, K. [U.S. Army Research Laboratory, Adelphi, Maryland 20783-1197 (United States); Myers, T. H. [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)

    2015-08-17

    Spectroscopic ellipsometry, ranging from 35 meV to 6 eV, was used to determine the dielectric functions of a series of molecular beam epitaxy-grown Hg{sub 1−x}Cd{sub x}Se thin films deposited on both ZnTe/Si(112) and GaSb(112) substrates. The fundamental band gap as well as two higher-order electronic transitions blue-shift with increasing Cd composition in Hg{sub 1−x}Cd{sub x}Se, as expected. Representing the free carrier absorption with a Drude oscillator, we found that the effective masses of Hg{sub 1−x}Cd{sub x}Se (grown on ZnTe/Si) vary between 0.028 and 0.050 times the free electron mass, calculated using the values of carrier concentration and the mobility obtained through Hall measurements. Using these effective masses, we determined the carrier concentrations of Hg{sub 1−x}Cd{sub x}Se samples grown on GaSb, which is of significance as films grown on such doped-substrates posit ambiguous results when measured by conventional Hall experiments. These models can serve as a basis for monitoring Cd-composition during sample growth through in-situ spectroscopic ellipsometry.

  17. Comparing FDTD and Ray-Tracing Models in Numerical Simulation of HgCdTe LWIR Photodetectors

    Science.gov (United States)

    Vallone, Marco; Goano, Michele; Bertazzi, Francesco; Ghione, Giovanni; Schirmacher, Wilhelm; Hanna, Stefan; Figgemeier, Heinrich

    2016-09-01

    We present a simulation study of HgCdTe-based long-wavelength infrared detectors, focusing on methodological comparisons between the finite-difference time-domain (FDTD) and ray-tracing optical models. We performed three-dimensional simulations to determine the absorbed photon density distributions and the corresponding photocurrent and quantum efficiency spectra of isolated n-on- p uniform-composition pixels, systematically comparing the results obtained with FDTD and ray tracing. Since ray tracing is a classical optics approach, unable to describe interference effects, its applicability has been found to be strongly wavelength dependent, especially when reflections from metallic layers are relevant. Interesting cavity effects around the material cutoff wavelength are described, and the cases where ray tracing can be considered a viable approximation are discussed.

  18. The Effect of Metal-Semiconductor Contact on the Transient Photovoltaic Characteristic of HgCdTe PV Detector

    Directory of Open Access Journals (Sweden)

    Haoyang Cui

    2013-01-01

    Full Text Available The transient photovoltaic (PV characteristic of HgCdTe PV array is studied using an ultrafast laser. The photoresponse shows an apparent negative valley first, then it evolves into a positive peak. By employing a combined theoretical model of pn junction and Schottky potential, this photo-response polarity changing curves can be interpreted well. An obvious decreasing of ratio of negative valley to positive peak can be realized by limiting the illumination area of the array electrode. This shows that the photoelectric effect of Schottky barrier at metal-semiconductor (M/S interface is suppressed, which will verify the correctness of the model. The characteristic parameters of transient photo-response induced from p-n junction and Schottky potential are extracted by fitting the response curve utilizing this model. It shows that the negative PV response induced by the Schottky barrier decreases the positive photovoltage generated by the pn junction.

  19. The effect of metal-semiconductor contact on the transient photovoltaic characteristic of HgCdTe PV detector.

    Science.gov (United States)

    Cui, Haoyang; Xu, Yongpeng; Yang, Junjie; Tang, Naiyun; Tang, Zhong

    2013-01-01

    The transient photovoltaic (PV) characteristic of HgCdTe PV array is studied using an ultrafast laser. The photoresponse shows an apparent negative valley first, then it evolves into a positive peak. By employing a combined theoretical model of pn junction and Schottky potential, this photo-response polarity changing curves can be interpreted well. An obvious decreasing of ratio of negative valley to positive peak can be realized by limiting the illumination area of the array electrode. This shows that the photoelectric effect of Schottky barrier at metal-semiconductor (M/S) interface is suppressed, which will verify the correctness of the model. The characteristic parameters of transient photo-response induced from p-n junction and Schottky potential are extracted by fitting the response curve utilizing this model. It shows that the negative PV response induced by the Schottky barrier decreases the positive photovoltage generated by the pn junction.

  20. Speciation of Aquatic Heavy Metals in Humic Substances by$^{111m}$Cd/$^{199m}$Hg-TDPAC

    CERN Multimedia

    2002-01-01

    Humic substances are ubiquitous in waters and soils and act as complexing agents for different heavy metals, e.g. Cd, Hg. Toxicity, reactivity, fixation and migration are therefore strongly influenced by the interactions between heavy metals and humic substances. Humic substances derive from postmortal materials such as rotten plants, have dark colours and usually a molecular weight between 500 and 10~000 Dalton. Complex formation studies with different heavy metal ions indicate at least two different kinds of metal sites. Usually, these studies are restricted to heavy metal concentrations 2 to 3 orders of magnitude higher than the natural heavy metal abundance (i.e. 10$^{-10}$ molar). This serious limitation can be overcome by the use of suitable radiosotope techniques capable of metal speciation at extreme sensitivity levels such as TDPAC (Time Differential Perturbed Angular Correlation of~$\\gamma$-rays). Thus, we studied the interaction of heavy metals with humic substances by monitoring the nuclear quadru...

  1. The use of helium ion RBS for profiling epitaxial layers of Cd sub x Hg sub 1-x Te

    Energy Technology Data Exchange (ETDEWEB)

    Avery, A.J.; Diskett, D.J.; Lane, D.W. (Royal Military Coll. of Science, Shrivenham, Swindon, Wiltshire (UK)); Giess, J.; Irvine, S.J.C. (Royal Signals and Radar Establishment, Malvern, Worcestershire (UK))

    1990-01-01

    This paper describes the application of helium ion RBS and channelling to the characterization of an epitaxial layer of Cd{sub x}Hg{sub 1-x}Te. The layer was grown by MOVPE on a substrate of GaAs as part of a programme for developing infrared detector materials. The use of RBS with the aid of computer techniques is discussed for obtaining compositional (x) profiles both within the layers and, in particular, in the near-surface region. Conventional- and grazing-geometry measurements have been used to establish layer quality and interfacial abruptness. Variations in composition close to the surface have been correlated with the conditions under which layer growth was terminated. Channelling measurements are presented for the assessment of the layer crystalline quality. (orig.).

  2. Structural, electronic, elastic, thermodynamic and phonon properties of LaX (X = Cd, Hg and Zn) compounds in the B2 phase

    Science.gov (United States)

    Örnek, Osman; Arıkan, Nihat

    2016-07-01

    The ab initio computations have been performed to examine the structural, elastic, electronic and phonon properties of cubic LaX (X = Cd, Hg and Zn) compounds in the B2 phase. The optimized lattice constants, bulk modulus, and its pressure derivative and elastic constants are evaluated and compared with available data. Electronic band structures and total and partial densities of states (DOS) have been derived for LaX (X = Cd, Hg and Zn) compounds. The electronic band structures show metallic character; the conductivity is mostly governed by La-5d states for three compounds. Phonon-dispersion curves have been obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume CV of LaX (X = Cd, Hg and Zn) compounds are calculated and discussed.

  3. Tandem quadruplication of HMA4 in the zinc (Zn) and cadmium (Cd) hyperaccumulator Noccaea caerulescens.

    Science.gov (United States)

    Ó Lochlainn, Seosamh; Bowen, Helen C; Fray, Rupert G; Hammond, John P; King, Graham J; White, Philip J; Graham, Neil S; Broadley, Martin R

    2011-03-10

    Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea.A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOS™ clones with insert sizes ∼20-40 kbp, and screened with a PCR-generated HMA4 genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs.Four tandem HMA4 repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of AtHMA4 in Arabidopsis thaliana. Promoter-reporter β-glucuronidase (GUS) fusion analysis of a NcHMA4 in A. thaliana revealed deregulated expression in roots and shoots, analogous to AhHMA4 promoters, but distinct from AtHMA4 expression which localised to the root vascular tissue.This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between N. caerulescens and A. halleri, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae.

  4. Tandem quadruplication of HMA4 in the zinc (Zn and cadmium (Cd hyperaccumulator Noccaea caerulescens.

    Directory of Open Access Journals (Sweden)

    Seosamh Ó Lochlainn

    Full Text Available Zinc (Zn and cadmium (Cd hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea.A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOS™ clones with insert sizes ∼20-40 kbp, and screened with a PCR-generated HMA4 genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs.Four tandem HMA4 repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of AtHMA4 in Arabidopsis thaliana. Promoter-reporter β-glucuronidase (GUS fusion analysis of a NcHMA4 in A. thaliana revealed deregulated expression in roots and shoots, analogous to AhHMA4 promoters, but distinct from AtHMA4 expression which localised to the root vascular tissue.This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between N. caerulescens and A. halleri, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae.

  5. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ni [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Jiang, Shiuh-Jen, E-mail: sjjiang@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Chen, Yen-Ling [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Sahayam, A.C. [National Centre for Compositional Characterisation of Materials (CCCM), Hyderabad (India)

    2015-02-20

    Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL{sup −1} Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g{sup −1} for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.

  6. [Effect of Ryegrass and Arbuscular Mycorrhizal on Cd Absorption by Varieties of Tomatoes and Cadmium Forms in Soil].

    Science.gov (United States)

    Chen, Yong-qin; Jiang, Ling; Xu, Wei-hong; Chi, Sun-lin; Chen, Xu-gen; Xie, Wen-wen; Xiong, Shi- juan; Zhang, Jin-zhong; Xiong, Zhi-ting

    2015-12-01

    Field trial was carried out to investigate the effects of ryegrass and arbuscular mycorrhizal single or compound treatment to two varieties of tomato ("Defu mm-8" and "Luobeiqi") on the plant growth, concentrations and accumulations of Cd as well as the impact on microorganisms, enzyme activities, pH and Cd forms in soil when exposed to Cd (5.943 mg · kg⁻¹). The results showed that dry weights of fruit, root, stem, leaf and plant significantly increased by single or compound treatment of ryegrass and arbuscular mycorrhizal by 14.1%-38.4% and 4.2%-18.3%, 20.9%-31.5% and 8.4%-10.3%, 13.0%-16.8% and 3.0%-9.5%, 10.7%- 16.8% and 2.7%-7.6%, 14.3%-36.6% and 4.5%-16.8%, respectively. The amounts of bacteria, fungi, actinomycetes of soil and the activities of urease, invertase, acid phosphatase, catalase in soil were increased by single or compound treatment of ryegrass and arbuscular mycorrhizal, and the soil microorganism amounts and enzyme activities significantly differed between the two varieties of tomato and treatments (P Cd, CAB-Cd, Fe-Mn-Cd and total Cd in soil were decreased, and the total Cd content was decreased by 16.9%-27.8%. Cadmium concentrations in fruit, leaf, stem and root of both varieties were significantly decreased by 6.9%-40.9%, 5.7%-40.1%, 4.6%-34.7% and 9.8%-42.4%, respectively. Cadmium accumulations in tomato were in order of leaf > stem > root > fruit. Comparing the two tomato varieties, Cd concentrations and Cd accumulations in fruit and plant were in order of "Luobeiqi" < "Defu mm-8" in the presence or absence of single or compound treatment of ryegrass and arbuscular mycorrhizal.

  7. Microbial toxicity of ionic species leached from the II-VI semiconductor materials, cadmium telluride (CdTe) and cadmium selenide (CdSe).

    Science.gov (United States)

    Ramos-Ruiz, Adriana; Zeng, Chao; Sierra-Alvarez, Reyes; Teixeira, Luiz H; Field, Jim A

    2016-11-01

    This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity.

  8. Phytoavailability of cadmium (Cd) to Pak choi (Brassica chinensis L.) grown in Chinese soils: a model to evaluate the impact of soil Cd pollution on potential dietary toxicity.

    Science.gov (United States)

    Rafiq, Muhammad Tariq; Aziz, Rukhsanda; Yang, Xiaoe; Xiao, Wendan; Stoffella, Peter J; Saghir, Aamir; Azam, Muhammad; Li, Tingqiang

    2014-01-01

    Food chain contamination by soil cadmium (Cd) through vegetable consumption poses a threat to human health. Therefore, an understanding is needed on the relationship between the phytoavailability of Cd in soils and its uptake in edible tissues of vegetables. The purpose of this study was to establish soil Cd thresholds of representative Chinese soils based on dietary toxicity to humans and develop a model to evaluate the phytoavailability of Cd to Pak choi (Brassica chinensis L.) based on soil properties. Mehlich-3 extractable Cd thresholds were more suitable for Stagnic Anthrosols, Calcareous, Ustic Cambosols, Typic Haplustalfs, Udic Ferrisols and Periudic Argosols with values of 0.30, 0.25, 0.18, 0.16, 0.15 and 0.03 mg kg-1, respectively, while total Cd is adequate threshold for Mollisols with a value of 0.86 mg kg-1. A stepwise regression model indicated that Cd phytoavailability to Pak choi was significantly influenced by soil pH, organic matter, total Zinc and Cd concentrations in soil. Therefore, since Cd accumulation in Pak choi varied with soil characteristics, they should be considered while assessing the environmental quality of soils to ensure the hygienically safe food production.

  9. Bioaccumulation of Hg, Cd and Pb by Fucus vesiculosus in single and multi-metal contamination scenarios and its effect on growth rate.

    Science.gov (United States)

    Henriques, Bruno; Lopes, Cláudia B; Figueira, Paula; Rocha, Luciana S; Duarte, Armando C; Vale, Carlos; Pardal, Miguel A; Pereira, Eduarda

    2017-03-01

    Results of 7-days exposure to metals, using environmentally realistic conditions, evidenced the high potential of living Fucus vesiculosus to remove Pb, Hg and Cd from contaminated salt waters. For different contamination scenarios (single- and multi-contamination), ca 450 mg L(-1) (dry weight), enable to reduce the concentrations of Pb in 65%, of Hg in 95% and of Cd between 25 and 76%. Overall, bioconcentration factors ranged from 600 to 2300. Elovich kinetic model described very well the bioaccumulation of Pb and Cd over time, while pseudo-second-order model adjusted better to experimental data regarding Hg. F. vesiculosus showed different affinity toward studied metals, following the sequence order: Hg > Pb > Cd. Analysis of metal content in the macroalgae after bioaccumulation, proved that all metal removed from solution was bound to the biomass. Depuration experiments reveled no significant loss of metal back to solution. Exposure to contaminants only adversely affected the organism's growth for the highest concentrations of Cd and Pb. Findings are an important contribute for the development of remediation biotechnologies for confined saline waters contaminated with trace metal contaminants, more efficient and with lower costs than the traditional treatment methods.

  10. The effect of cadmium vacancies on the optical properties of chemically prepared CdS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Madan, Shikha; Kumar, Jitender; Singh, Inderpreet; Madhwal, Devinder; Bhatnagar, P K; Mathur, P C, E-mail: shikhamadan16@gmail.co [Material Science Laboratory, Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India)

    2010-10-15

    CdS quantum dots (QDs) in a polyvinyl alcohol (PVA) matrix have been grown by a chemical method and are characterized by transmission electron microscopy (TEM), UV-vis absorption, photoluminescence (PL) and energy dispersive x-ray diffraction (EDX). TEM studies of CdS films show that a nearly spherical cluster of CdS QDs with an average radius of 10-15 nm is formed. From absorption measurements, it is observed that with increasing the PVA concentration from 5 to 8 wt.%, the absorption edge shifts from 3.1 to 3.6 eV, which is attributed to an increase in quantum confinement with decreasing the QD size. PL studies in an energy range of 1.8-3.3 eV show two distinct peaks. The higher-energy peak corresponds to band edge emission, whereas the lower-energy peak corresponds to defect emission. EDX results revealed that the atomic concentration of cadmium is much lower than that of sulfur, indicating that cadmium vacancies are predominant. It was concluded that cadmium vacancies are mainly responsible for defect emission in the PL spectrum.

  11. Luminescence and influence of defect concentration on excitons in $^{197}\\!$Hg / $^{197}\\!$Au-doped CdTe

    CERN Document Server

    Hamann, J; Deicher, M; Filz, T; Ostheimer, V; Strasser, F; Wolf, H; Wichert, T

    1999-01-01

    CdTe, implanted with $^{197}\\!$Hg ions, which decay to $^{197}\\!$Au with a half-life of 64.1 h, was investigated by photoluminescence (PL) spectroscopy. The results unambiguously verify the assignments of both, the donor–acceptor pair transition at 1.335 eV, which corresponds to an acceptor level with E$\\scriptstyle_{A}$=263 meV, and the recombination of excitons bound to neutral acceptors at 1.57606 eV to single Au atoms on Cd sites. In addition, the dependence of the intensities of excitonic lines on the defect concentration was investigated quantitatively. The observed intensities are well explained, assuming that a defect can only bind an exciton if there is no additional defect within the volume of the bound exciton. The ratio between the exciton radii of the Cu and Au-bound excitons R$\\scriptscriptstyle^\\textrm{Cu}_{exc}$ / R$\\scriptscriptstyle^\\textrm{Au}_{exc}$ = 1.2$\\pm$0.2 obtained from this model is in good agreement with the ratio derived from the diamagnetic shift parameters of the two correspo...

  12. Data on HepG2 cells changes following exposure to cadmium sulphide quantum dots (CdS QDs

    Directory of Open Access Journals (Sweden)

    Laura Paesano

    2017-04-01

    Full Text Available The data included in this paper are associated with the research article entitled "Markers for toxicity to HepG2 exposed to cadmium sulphide quantum dots; damage to mitochondria" (Paesano et al. [1]. The article concerns the cytotoxic and genotoxic effects of CdS QDs in HepG2 cells and the mechanisms involved. In this dataset, changes in expression levels of candidate genes are reported, together with details concerning synthesis and properties of CdS QDs, additional information obtained through literature survey, measures of the mitochondrial membrane potential and the glutathione redox state.

  13. Characterization of cadmium ((108)Cd) distribution and accumulation in Tagetes erecta L. seedlings: effect of split-root and of remove-xylem/phloem.

    Science.gov (United States)

    Qin, Qin; Li, Xuemei; Wu, Haiyan; Zhang, Yinqiu; Feng, Qian; Tai, Peidong

    2013-11-01

    Tagetes erecta has a high potential for cadmium (Cd) phytoremediation. Through several hydroponic experiments, characteristics of (108)Cd distribution and accumulation were investigated in T. erecta with split -roots or removed xylem/phloem. The results showed that (108)Cd transport from roots to aboveground tissues showed the homolateral transport phenomenon in split-root seedlings. (108)Cd content of leaves on the +(108)Cd side and the -(108)Cd side was not significantly different, which implied that there was horizontal transport of (108)Cd from the +(108)Cd side to the -(108)Cd side in cut-root seedlings. Like (108)Cd transport, the transport of (70)Zn was homolateral. Reduction of water consumption in the removed xylem treatment significantly decreased (108)Cd accumulation; whereas, the removed phloem treatment had no significant effect on water consumption, but did decrease (108)Cd accumulation in leaves of the seedlings. The removal of phloem significantly reduced distal leaf (108)Cd content, which was significantly lower than that in the basal leaves in both the split-root and unsplit-root seedlings. Overall, the results presented in this study revealed that the root to aboveground cadmium translocation via phloem is as an important and common physiological process as xylem determination of the cadmium accumulation in stems and leaves of marigold seedlings. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Study of structure-function alterations of olfactory organ in Hg2+、Cd2+ poisoned Tilapia. Sp and the detoxifcation of Ca2+%Hg2+、Cd2+对鱼类嗅觉的毒性及Ca2+的解毒作用

    Institute of Scientific and Technical Information of China (English)

    陈荣; 柴敏娟

    2001-01-01

    When these fish (Tilapia. Sp) are exposed to four different kinds of Hg2+ or Cd2+ solutions, the structure-function alterations of olfactory organ are systematically studied by electrophysiological and histological method, and the detoxifcation of Ca2+ on Hg2+ or Cd2+ is also studied. The results are shown as follows: 1) Both of Hg2+ and Cd2+ are effective inhibitors on the EOG responses, and the inhibitions become stronger with the increasing of the ions concentration and prolonging of the polluted time. The IC50 (concentration which inhibited respoonses by 50%) values of Hg2+ and Cd2+ are 67.73 μg/L and 33.90 μg/L, respectively. The inhibitory effect of Cd2+ is stronger than that of Hg2+. 2) The inhibiting effects of the mixtures containing Ca2+ (80 mg/L)+Hg2+ or Ca2+ (80 mg/L) + Cd2+ weaker than that of single heavy metal ion with the same concentration, and the detoxifcation of Ca2+ on Hg2+-poisoned fish is much more pronounced than that of Cd2+. The results indicate that Ca2+ has some detoxifcation on the Hg2+ and Cd2+-poisoned fish. 3) After 15 days exposure to four polluting solution of 10、50 μg/L Hg2+ or Cd2+ respectively, the olfactory epithelium of all polluted fish are observed different degree damage by light microscopy. In the low concentration groups, the main alteration is the hypertrophy of mucous cells in the non-sensory region. In the high concentration groups, some vacuoles appear in the regional olfactory epithelium; some cells spill over the surface of olfactory epithelium from the region of dead sensory cells.   When the olfactory epithelium of Tilapia. SP is exposed to the mixture containing 80 mg/L Ca2+ and 10 μg/L Hg2+ or Cd2+, no changes is observed by light microscopy. But mixture groups containing 80 mg/L Ca2+ and 50 μg/L Hg2+ or Cd2+, olfactory epithelium has cellular shrinkage and no vacuole presented.%以罗非鱼为实验对象,采用电生理学和组织学方法系统研究了4种不同浓度的Hg2+、Cd2+污染液对

  15. Synthesis and characterization of aspartic acid-capped CdS/ZnS quantum dots in reverse micelles and its application to Hg(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mohammad Saeid, E-mail: mshosseini1336@yahoo.com; Kamali, Mohsen

    2015-11-15

    In this work, CdS/ZnS quantum dots (QDs) coated with aspartic acid (AsA) were synthesized in reverse micelles. The synthesized QDs were characterized by XRD, TEM, IR and photoluminescence (PL) spectroscopy. It was found that the intensity of CdS/ZnS QDs coated with AsA is much greater than CdS, and CdS/ZnS QDs. The interaction of some heavy metal ions with CdS/ZnS/AsA QDs was investigated at different buffering pH media. Based on the PL quenching of the QDs in the presence of each one of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be easily determined in contaminated atmospheric environments with the detection limit of 0.05 mg m{sup −3}. The results were satisfactorily confirmed by cold vapor atomic absorption spectrometric method. - Highlights: • A new CdS/ZnS quantum dot capped with aspartic acid (DDBA) was prepared. • The prepared QDs benefit from a favorable fluorescence. • Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. • The determination of Hg(II) is feasible in the present of many co-existence metal ions. • The method benefits from a high-speed and considerable simplicity for Hg(II) determination.

  16. Whole-body aerosol exposure of cadmium chloride (CdCl{sub 2}) and tetrabromobisphenol A (TBBPA) induced hepatic changes in CD-1 male mice

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yuanhong; Hu, Yabing; Liu, Shuyun; Zheng, Huiying; Wu, Xiaojuan; Huang, Zhengyu; Li, Hao; Peng, Baoqi; Long, Jinlie [Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035 (China); Pan, Bishu [Taizhou Center for Disease Control and Prevention, Taizhou 318000 (China); Huang, Changjiang, E-mail: cjhuang5711@163.com [Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035 (China); Dong, Qiaoxiang, E-mail: dqxdong@163.com [Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035 (China)

    2016-11-15

    Highlights: • Hepatotoxicity of TBBPA and Cd aerosol co-exposure was evaluated in CD-1 male mice. • Hepatic changes include focal necrosis, increased organ weight, and elevated enzymes. • TBBPA group exhibited highest hepatic toxicity followed by co-exposure and Cd groups. • We did not observe any synergistic effect of hepatic toxicity between TBBPA and Cd. • TBBPA/Cd suppressed antioxidant defensive mechanisms and increased oxidative stress. - Abstract: Cadmium (Cd) and tetrabromobisphenol A (TBBPA) are two prevalent contaminants in e-waste recycling facilities. However, the potential adversely health effect of co-exposure to these two types of pollutants in an occupational setting is unknown. In this study, we investigated co-exposure of these two pollutants on hepatic toxicity in CD-1 male mice through a whole-body aerosol inhalation route. Specifically, mice were exposed to solvent control (5% DMSO), Cd (8 μg/m{sup 3}), TBBPA (16 μg/m{sup 3}) and Cd/TBBPA mixture for 8 h/day and 6 days a week for 60 days. Hepatic changes include increased organ weight, focal necrosis, and elevated levels of liver enzymes in serum. These changes were most severe in mice exposed to TBBPA, followed by Cd/TBBPA mixture and Cd. These chemicals also led to suppressed antioxidant defensive mechanisms and increased oxidative stress. Further, these chemicals induced gene expression of apoptosis-related genes, activated genes encoding for phase I detoxification enzymes and inhibited genes encoding for phase II detoxification enzymes. These findings indicate that the hepatic damages induced by subchronic aerosol exposure of Cd and TBBPA may result from the oxidative damages caused by excessive ROS production when these chemicals were metabolized in the liver.

  17. Studies on a novel mask technique with high selectivity and aspect-ratio patterns for HgCdTe trenches ICP etching

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Li, Y.; Huang, J.; Yin, W. T.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2012-06-01

    A novel mask technique, combining high selectivity silicon dioxide patterns over high aspect-ratio photoresist (PR) patterns has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal plane arrays (IRFPAs). High-density silicon dioxide film covering high aspect-ratio PR patterns was deposited at the temperature of 80°C and silicon dioxide film patterns over high aspect-ratio PR patterns of HgCdTe etching samples was developed by standard photolithography and wet chemical etch. Scanning electron microscopy (SEM) shows that the surfaces of inductively coupled plasma (ICP) etched samples are quite clean and smooth. The etching selectivity between the novel mask and HgCdTe of the samples is increased to above 32: 1 while the side-wall impact of etching plasma is suppressed by the high aspect ratio patterns. These results show that the combined patterning of silicon dioxide film and thick PR film is a readily available and promising masking technique for HgCdTe mesa etching.

  18. Fluorescent sensor for selective determination of copper ion based on N-acetyl-L-cysteine capped CdHgSe quantum dots.

    Science.gov (United States)

    Wang, Qingqing; Yu, Xiangyang; Zhan, Guoqing; Li, Chunya

    2014-04-15

    Using N-acetyl-L-cysteine as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared N-acetyl-L-cysteine capped CdHgSe quantum dots were thoroughly characterized by transmission electron microscopy, X-ray diffraction spectroscopy and FTIR. A fluorescent sensor for selective determination of copper ions was developed using N-acetyl-L-cysteine capped CdHgSe quantum dots as fluorescent probe. The fluorescence intensity of N-acetyl-L-cysteine capped CdHgSe quantum dots decreased when interacted with copper ions due to the formation of coordination complex and aggregates. The method possesses high selectivity and is not influenced by some potential interferences such as Ag(+), Zn(2+), Co(2+) and Ni(2+). Under the optimal conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of copper ions in the range of 1.0×10(-9)-4.0×10(-7) mol L(-1), with a detection limit as low as 2.0×10(-10) mol L(-1) (S/N=3). The developed method had been successfully employed to determine Cu(2+) in shrimp and South-lake water samples, and the results were verified by atomic absorption spectroscopy. The fluorescent sensor was demonstrated to be selective, sensitive and simple for copper ion determination, and promise for practical applications.

  19. The effect of dephasing on edge state transport through p-n junctions in HgTe/CdTe quantum wells.

    Science.gov (United States)

    Zhang, Ying-Tao; Song, Juntao; Sun, Qing-Feng

    2014-02-26

    Using the Landauer-Büttiker formula, we study the effect of dephasing on the transport properties of the HgTe/CdTe p-n junction. It is found that in the HgTe/CdTe p-n junction the topologically protected gapless helical edge states manifest a quantized 2e²/h plateau robust against dephasing, in sharp contrast to the case for the normal HgTe/CdTe quantum well. This robustness of the transport properties of the edge states against dephasing should be attributed to the special construction of the HgTe/CdTe p-n junction, which limits the gapless helical edge states to a very narrow region and thus weakens the influence of the dephasing on the gapless edge states to a large extent. Our results demonstrate that the p-n junction could be a substitute device for use in experimentally observing the robust edge states and quantized plateau. Finally, we present a feasible scheme based on current experimental methods.

  20. Metallothionein induction by Cu, Cd and Hg in Dicentrarchus labrax liver: assessment by RP-HPLC with fluorescent detection and spectrophotometry

    OpenAIRE

    Jebali, Jamel; Banni, Mohamed; Gerbej, Hamadi; Boussetta, Hamadi; López-Barea, Juan; Alhama, José

    2008-01-01

    Metallothionein induction by Cu, Cd and Hg in Dicentrarchus labrax liver: assessment by RP-HPLC with fluorescent detection and spectrophotometry correspondance: Corresponding author. Tel.: +34 957 218082; fax: +34 957 218688. (Alhama, Jose) (Alhama, Jose) Laboratoire de Biochimie et de Toxicologie Environmentale--> , Institut Superieur d?Agronomie de Chott-Mariem--> , 4042 Sousse--> - TUNISIA (Jebali,...

  1. [Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) captured in Veracruz, Mexico].

    Science.gov (United States)

    Mendoza-Díaz, Fernando; Serrano, Arturo; Cuervo-López, Liliana; López-Jiménez, Alejandra; Galindo, José A; Basañez-Muñoz, Agustin

    2013-06-01

    Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was an adult female, three were juvenile males, and three juvenile females. Four heavy metals (Hg, Pb, Cd, and Cr) and one metaloid (As) were analyzed in shark livers using an atomic absorption spectrophotometry with flame and hydride generator. Our results showed that the maximum concentrations found were: Hg = 0.69 mg/kg, Cd = 0.43 mg/kg, As = 27.37 mg/kg, Cr = 0.70 mg/kg. The minimum concentrations found were: As = 14.91 mg/kg, Cr = 0.35 mg/kg. The Pb could not be determined because the samples did not have the spectrophotometer minimum detectable amount (0.1 mg/kg). None of the 19 samples analyzed showed above the permissible limits established by Mexican and American laws. There was a correlation between shark size and Cr and As concentration (Pearson test). The concentration of Cr and As was observed to be higher in bigger animals. There was not a significant difference in heavy metals concentration between juveniles and adults; however, there was a difference between males and females. A higher Cr concentration was found in females when compared to males. None of the samples exceed the maximum limit established by the laws of Mexico and the United States of America. Much longer studies are needed with C. limbatus and other species caught in the region, in order to determine the degree of contaminants exposure in aquatic ecosystems

  2. Whole-body aerosol exposure of cadmium chloride (CdCl2) and tetrabromobisphenol A (TBBPA) induced hepatic changes in CD-1 male mice.

    Science.gov (United States)

    Chen, Yuanhong; Hu, Yabing; Liu, Shuyun; Zheng, Huiying; Wu, Xiaojuan; Huang, Zhengyu; Li, Hao; Peng, Baoqi; Long, Jinlie; Pan, Bishu; Huang, Changjiang; Dong, Qiaoxiang

    2016-11-15

    Cadmium (Cd) and tetrabromobisphenol A (TBBPA) are two prevalent contaminants in e-waste recycling facilities. However, the potential adversely health effect of co-exposure to these two types of pollutants in an occupational setting is unknown. In this study, we investigated co-exposure of these two pollutants on hepatic toxicity in CD-1 male mice through a whole-body aerosol inhalation route. Specifically, mice were exposed to solvent control (5% DMSO), Cd (8μg/m(3)), TBBPA (16μg/m(3)) and Cd/TBBPA mixture for 8h/day and 6days a week for 60 days. Hepatic changes include increased organ weight, focal necrosis, and elevated levels of liver enzymes in serum. These changes were most severe in mice exposed to TBBPA, followed by Cd/TBBPA mixture and Cd. These chemicals also led to suppressed antioxidant defensive mechanisms and increased oxidative stress. Further, these chemicals induced gene expression of apoptosis-related genes, activated genes encoding for phase I detoxification enzymes and inhibited genes encoding for phase II detoxification enzymes. These findings indicate that the hepatic damages induced by subchronic aerosol exposure of Cd and TBBPA may result from the oxidative damages caused by excessive ROS production when these chemicals were metabolized in the liver.

  3. 10.6μm激光对HgCdTe焦平面器件热应力的分析%Theoretical analysis of thermal-stress effect of HgCdTe infrared focal plane device induced by 10.6 μm laser

    Institute of Scientific and Technical Information of China (English)

    郝向南; 聂劲松; 李化; 卞进田; 雷鹏

    2012-01-01

    建立了HgCdTe红外焦平面器件的多膜层理论模型,利用有限元分析的方法,对10.6 μm激光辐照下HgCdTe红外焦平面器件的升温情况与热应力分布情况进行模拟,并通过参考已有文献的实验结果,验证了理论模型的合理性.理论分析结果表明:激光作用时探测器的温度场变化剧烈,200 W/cm2连续激光作用1 s后,HgCdTe感光层所受热应力为-986 MPa;脉宽100 ns,功率密度15 MW/cm2脉冲激光作用后,HgCdTe感光层所受热应力为-1300 MPa,都比器件制造过程中由于热失配而产生的热应力大;应力损伤发生的概率增大,可能比热损伤先发生,是HgCdTe红外焦平面器件激光损伤中的重要原因.%Muti-layer theoretical Model of HgCdTe Infrared Focal Plane Device was established. With the method of finite element analysis, temperature field and thermal-stress field induced by 10.6 μm laser were simulated. By considering experiments carried out in other papers as reference,the rationality and feasibility of the muti-layer model are proved. Results of theoretical analysis indicates that the temperature field changes greatly when irradiated by laser. With CW laser of 200 W/cm2 power density irradiating the sensor for 1 s, thermal-stress of HgCdTe photo-sensitive surface is -986MPa:With pulsed laser of 100 ns and 15 MW/cm2 irradiating the sensor,thermal-stress of HgCdTe photo-sensitive surface is - 1300 Mpa. The thermal-stress mentioned above are both beyond that caused by thermal-mismatch in the production process. Besides, the probability of thermal-stress damage increases and may happen before thermal damage,which should be an important factor in the research of laser damage to HgCdTe Infrared Focal Plane Device.

  4. Hydrothermal syntheses and characterization of two novel luminescent Cadmium(II) frameworks: From 1D infinite triple Cd-(trz)-Cd bridges to a rare I2O0 network with 2D Cd-Br-Cd inorganic connectivity

    Science.gov (United States)

    Liu, Shi Xin; Li, Jian Hui; Wang, You You; Wu, Xiang Xia; Huo, Jian Zhong; Ding, Bin; Wang, Xiu Guang; Zhu, Zhao Zhou; Xia, Jun

    2015-05-01

    Using the 4-substituted-1,2,4-triazole derivate ligand 4-p-tolyl-1,2,4-triazole (L), two novel luminescent Cadmium(II) frameworks, namely {[Cd(μ2-L)3]·(NO3)2·L}n (1) and [Cd1.5(μ2-L)(μ2-Br)2(μ3-Br)]n (2) have been isolated under hydrothermal conditions. The structural analysis reveals that 1 presents a one-dimensional (1D) chain structural motif containing novel infinite triple Cd-(trz)-Cd bridges (triply trz-bridged M-M species). While 2 presents a rare I2O0 type framework, in which the infinite 2D Cd-Br-Cd inorganic connectivity with a 4-connected Kagome topology can be observed. The FT-IR, PXRD and thermal stabilities of 1-2 have investigated. The solid-state photo-luminescent spectra of organic ligand L and 1-2 also have been measured indicating strong emission bands.

  5. The energetic impact of small Cd{sub x}Te{sub y} clusters on Cadmium Telluride

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Miao, E-mail: M.Yu2@lboro.ac.uk; Kenny, Steven D., E-mail: S.D.Kenny@lboro.ac.uk

    2015-06-01

    Cadmium Telluride (CdTe) is an excellent material for low-cost, high efficiency thin film solar cells. It is important to do research on how these defects are formed during the growth process, since defects lower the efficiency of solar cells. In this work we use computer simulation to predict the growth of a sputter deposited CdTe thin film. Single deposition tests have been performed, to study the behaviour of deposited clusters under different conditions. We deposit a Cd{sub x}Te{sub y} (x,y = 0,1) cluster onto the (100) and (111) Cd and Te terminated surfaces with energies ranging from 1 to 40 eV. More than 1000 simulations have been performed for each of these cases so as to sample the possible deposition positions and to collect sufficient statistics. The results show that Cd atoms are more readily sputtered from the surface than Te atoms and the sticking probability is higher on Te terminated surfaces than Cd terminated surfaces. They also show that increasing the deposition energy typically leads to an increase in the number of atoms sputtered from the system and tends to decrease the number of atoms that sit on or in the surface layer, whilst increasing the number of interstitials observed. - Highlights: • Deposition of Cd, Te and CdTe particles on (100) and (111) Cd and Te surfaces • Cd atoms are more readily sputtered from the surface than Te atoms. • The Te terminated surfaces have a higher sticking probability than the Cd ones. • Higher impact energies imply more sputtered atoms from the surface.

  6. Dark conductivity and photoconductivity of amorphous Hg0.78Cd0.22Te thin films

    Institute of Scientific and Technical Information of China (English)

    Qiu Feng; Ji Rongbin; Xiang Jinzhong; Kong Jincheng; Yu Lianjie; Kong Lingde; Wang Guanghua; Li Xiongjun; Yang Lili; Li Cong

    2011-01-01

    This paper reports the dark conductivity and photoconductivity of amorphous Hg0.78Cd0.22 Te thin films deposited on an Al2O3 substrate by RF magnetron sputtering.It is determined that dark conduction activation energy is 0.417 eV for the as-grown sample.Thermal quenching is absent for the as-grown sample during the testing temperature zone,but the reverse is true for the polycrystalline sample.Photosensitivity shows the maximum at 240 K for amorphous thin films,while it is higher for the as-grown sample than for polycrystalline thin films in the range from 170 to 300 K.The recombination mechanism is the monomolecular recombination process at room temperature,which is different from the low temperature range.Theμτ-product is low in the range of 10-11-10-9 cm2/V,which indicates that some defect states exist in the amorphous thin films.

  7. First principles study of structural, electronic, elastic and thermal properties of YX (X = Cd, In, Au, Hg and Tl) intermetallics

    Science.gov (United States)

    Chouhan, Sunil Singh; Pagare, Gitanjali; Rajagopalan, M.; Sanyal, S. P.

    2012-08-01

    The structural, electronic, elastic and thermal properties of YX (X = Cd, In, Au, Hg and Tl) intermetallic compounds crystallizing in B2-type structure have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. Amongst all the YX compounds, YIn is stable in distorted tetragonal (P4/mmm) CuAu-type structure at ambient pressure with very small energy difference of 0.00681 Ry. but it undergoes to CsCl-type (B2 phase) structure at 23.3 GPa. Rest of the compounds are stable in B2 structure at ambient condition. The values of elastic moduli as a function of pressure are also reported. The ductility of these compounds has been analyzed using the Pugh rule. Our calculated results indicate that YTl is the most ductile amongst all the B2-YX compounds. YAu is the hardest and less compressible compound due to the largest bulk modulus. The elastic properties such as Young's modulus (E), Poisson's ratio (σ) and anisotropic ratio (A) are also predicted. The anisotropic factor is found to be unity for YHg which shows that this compound is isotropic.

  8. Effect of surface fields on the dynamic resistance of planar HgCdTe mid-wavelength infrared photodiodes

    Science.gov (United States)

    He, Kai; Zhou, Song-Min; Li, Yang; Wang, Xi; Zhang, Peng; Chen, Yi-Yu; Xie, Xiao-Hui; Lin, Chun; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao

    2015-05-01

    This work investigates the effect of surface fields on the dynamic resistance of a planar HgCdTe mid-wavelength infrared photodiode from both theoretical and experimental aspects, considering a gated n-on-p diode with the surface potential of its p-region modulated. Theoretical models of the surface leakage current are developed, where the surface tunnelling current in the case of accumulation is expressed by modifying the formulation of bulk tunnelling currents, and the surface channel current for strong inversion is simulated with a transmission line method. Experimental data from the fabricated devices show a flat-band voltage of V F B = - 5.7 V by capacitance-voltage measurement, and then the physical parameters for bulk properties are determined from the resistance-voltage characteristics of the diode working at a flat-band gate voltage. With proper values of the modeling parameters such as surface trap density and channel electron mobility, the theoretical R 0 A product and corresponding dark current calculated from the proposed model as functions of the gate voltage Vg demonstrate good consistency with the measured values. The R 0 A product remarkably degenerates when Vg is far below or above VFB because of the surface tunnelling current or channel current, respectively; and it attains the maximum value of 5.7 × 10 7 Ω . cm 2 around the transition between surface depletion and weak inversion when V g ≈ - 4 V , which might result from reduced generation-recombination current.

  9. TEQUILA: NIR camera/spectrograph based on a Rockwell 1024x1024 HgCdTe FPA

    Science.gov (United States)

    Ruiz, Elfego; Sohn, Erika; Cruz-Gonzales, Irene; Salas, Luis; Parraga, Antonio; Perez, Manuel; Torres, Roberto; Cobos Duenas, Francisco J.; Gonzalez, Gaston; Langarica, Rosalia; Tejada, Carlos; Sanchez, Beatriz; Iriarte, Arturo; Valdez, J.; Gutierrez, Leonel; Lazo, Francisco; Angeles, Fernando

    1998-08-01

    We describe the configuration and operation modes of the IR camera/spectrograph: TEQUILA based on a 1024 X 1024 HgCdTe FPA. The optical system will allow three possible modes of operation: direct imaging, low and medium resolution spectroscopy and polarimetry. The basic system is being designed to consist of the following: 1) A LN(subscript 2) dewar that allocates the FPA together with the preamplifiers and a 24 filter position cylinder. 2) Control and readout electronics based on DSP modules linked to a workstation through fiber optics. 3) An opto-mechanical assembly cooled to -30 degrees that provides an efficient operation of the instrument in its various modes. 4) A control module for the moving parts of the instrument. The opto-mechanical assembly will have the necessary provision to install a scanning Fabry-Perot interferometer and an adaptive optics correction system. The final image acquisition and control of the whole instrument is carried out in a workstation to provide the observer with a friendly environment. The system will operate at the 2.1 m telescope at the Observatorio Astronomico Nacional in San Pedro Martir, B.C. (Mexico), and is intended to be a first-light instrument for the new 7.8m Mexican IR-Optical Telescope.

  10. Human exposure to mercury, lead and cadmium through consumption of canned mackerel, tuna, pilchard and sardine.

    Science.gov (United States)

    Okyere, H; Voegborlo, R B; Agorku, S E

    2015-07-15

    Total mercury (Hg), cadmium (Cd) and lead (Pb) concentrations were determined in canned fish on the Ghanaian market. Total mercury was determined using an automatic mercury analyzer while cadmium and lead levels were determined by flame atomic absorption spectrophotometry. The metal contents in the samples, expressed in μg g(-1) (wet weight), varied from canned fish from the Ghanaian market have concentrations well below the permissible FAO/WHO for these toxic metals. Thus considering the Provisional Tolerable Weekly Intake (PTWI) of Hg, Pb and Cd the levels obtained in this study are unlikely to constitute a significant exposure to the public through consumption of moderate amounts.

  11. Cadmium uptake and translocation in tumbleweed (Salsola kali), a potential Cd-hyperaccumulator desert plant species: ICP/OES and XAS studies.

    Science.gov (United States)

    de la Rosa, Guadalupe; Peralta-Videa, Jose R; Montes, Milka; Parsons, Jason G; Cano-Aguilera, Irene; Gardea-Torresdey, Jorge L

    2004-06-01

    Cadmium is a heavy metal, which, even at low concentrations, can be highly toxic to the growth and development of both plants and animals. Plant species vary extensively in their tolerance to excess cadmium in a growth medium and very few cadmium-tolerant species have been identified. In this study, tumbleweed plants (Salsola kali) grown in an agar-based medium with 20 mgl(-1) of Cd(II) did not show phytotoxicity, and their roots had the most biomass (4.5 mg) (P < 0.05) compared to the control plants (2.7 mg) as well as other treated plants. These plants accumulated 2696, 2075, and 2016 mg Cd kg(-1) of dry roots, stems, and leaves, respectively. The results suggest that there is no restricted cadmium movement in tumbleweed plants. In addition, the amount of Cd found in the dry leaf tissue suggests that tumbleweed could be considered as potential cadmium hyperaccumulating species. X-ray absorption spectroscopy studies demonstrated that in roots, cadmium was bound to oxygen while in stems and leaves, the metal was attached to oxygen and sulfur groups. This might imply that some small organic acids are responsible for Cd transport from roots to stems and leaves. In addition, it might be possible that the plant synthesizes phytochelatins in the stems, later coordinating the absorbed cadmium for transport and storage in cell structures. Thus, it is possible that in the leaves, Cd either exists as a Cd-phytochelatin complex or bound to cell wall structures. Current studies are being performed in order to elucidate the proposed hypothesis.

  12. Effects of Gravity on the Double-Diffusive Convection during Directional Solidification of a Non-Dilute Alloy with Application to the HgCdTe

    Science.gov (United States)

    Bune, Andris; Gillies, Donald; Lehoczky, Sandor

    1999-01-01

    General 2-D and 3-D finite element model of non-dilute alloy solidification was used to simulate growth of HgCdTe in terrestrial and microgravity conditions. Parametric research was undertaken to investigate effects of gravity level, gravity vector orientation and growth velocity on the pattern of melt convection, shape of crystal/melt interface and radial thermal gradient. Verification of the model was undertaken by comparison with previously published results. For low growth velocities plane front solidification occurs. The location and the shape of the interface was determined using melting temperatures obtained from the HgCdTe liquidus curve. The low thermal conductivity of the solid HgCdTe causes thermal short circuit through the ampoule walls, resulting in curved isotherms in the vicinity of the interface. Double-diffusive convection in the melt is caused by radial temperature gradients and by material density inversion with temperature. Cooling from below and the rejection at the solid-melt interface of the heavier HgTe-rich solute each tend to reduce convection. Because of these complicating factors dimensional rather then non-dimensional modeling was performed. For gravity levels higher then 10(exp -7) of terrestrial one it was found that the maximum convection velocity is extremely sensitive to gravity vector orientation and can be reduced at least by 50% by choosing proper orientation of the ampoule. The predicted interface shape is in agreement with one obtained experimentally by quenching.

  13. Effects of Gravity on the Double-Diffusive Convection During Directional Solidification of a Non-Dilute Alloy with Application to HgCdTe

    Science.gov (United States)

    Bune, Andris V.; Gillies, Donald C.; Lehoczky, Sandor L.

    1999-01-01

    A general 2-D and 3-D finite element model of non-dilute alloy solidification was used to simulate growth of HgCdTe in terrestrial and microgravity conditions. Verification of the 3-D model was undertaken by comparison with previously published results on convection in an inclined cylinder. For low growth velocities, plane front solidification occurs. The location and the shape of the interface were determined using melting temperatures obtained from the HgCdTe liquidus curve. The low thermal conductivity of the solid HgCdTe causes a thermal short circuit through the ampoule walls, resulting in curved isotherms in the vicinity of the interface. Double-diffusive convection in the melt is caused by radial temperature gradients and by material density inversion due to the combined effects of composition and temperature. Cooling from below and the rejection at the solid-melt interface of the heavier HgTe-rich solute each tend to reduce convection. Because of these complicating factors, dimensional rather than non-dimensional modeling was performed. the predicted interface shape is in agreement with one obtained experimentally by quenching.

  14. Cadmium biosorption by free and immobilised microorganisms cultivated in a liquid soil extract medium: effects of Cd, pH and techniques of culture.

    Science.gov (United States)

    Lebeau, T; Bagot, D; Jézéquel, K; Fabre, B

    2002-05-27

    Instead of soil clean-up, a process not very technically and economically suited to agricultural soil contaminated by heavy metals (with a low concentration of heavy metals but highly or potentially highly contaminated surfaces), the control of the transfer of cadmium from the soil to the crops may well be a convenient method. We tested the bacterium ZAN-044, the actinomycete R27 and a basidiomycete Fomitopsis pinicola isolated for their ability to biosorb Cd, in order to inoculate agricultural soils afterwards. We then compared the cadmium biosorption by viable microbial cells which were free or immobilised in alginate beads and incubated in a soil extract liquid medium at various pH values (5, 6 and 7) and cadmium concentrations (1 and 10 mg/l). The Cd concentration in the medium had the most important effect on the percentage of Cd biosorbed by the microorganisms, but the culture mode (free or immobilised cells) was not a side effect. In the case of F. pinicola and the actinomycete R27, the percentage of Cd biosorbed by free cells did not decrease when the Cd concentration in the medium increased (6-42% at the lowest Cd concentration to 11-48% at 10 mg Cd/l). On the other hand, with a low Cd concentration (1 mg Cd/l), the percentage of Cd biosorbed by the bacterium ZAN-044 was maximum (69%) at pH 7, while this bacterium did not grow at 10 mg Cd/l and it did not accumulate Cd. For the three micro-organisms tested, relatively low specific biosorptions of Cd were observed, when the microorganisms were cultivated with a soil extract medium ('poor' medium), comparatively to those with a 'rich' medium. Finally, the choice of microorganism for the inoculation of contaminated soils depends on the cadmium level in the medium and on the distribution of the metal between the biomass and the medium.

  15. Cadmium (Cd) Localization in Tissues of Cotton (Gossypium hirsutum L.), and Its Phytoremediation Potential for Cd-Contaminated Soils.

    Science.gov (United States)

    Chen, Zhifan; Zhao, Ye; Fan, Lidong; Xing, Liteng; Yang, Yujie

    2015-12-01

    Phytoremediation using economically valuable, large biomass, non-edible plants is a promising method for metal-contaminated soils. This study investigated cotton's tolerance for Cd and remediation potential through analyzing Cd bioaccumulation and localization in plant organs under different soil Cd levels. Results showed cotton presents good tolerance when soil Cd concentration ≤20.26 mg kg(-1). Cotton had good Cd accumulation ability under low soil Cd levels (soil Cd, while roots and stems were the main compartments of Cd storage. Cd complexation to other organic constituents in root and stem cell sap could be a primary detoxifying strategy. Therefore, cotton is a potential candidate for phytoremediation of Cd-contaminated soils.

  16. Mercury Cadmium Selenide for Infrared Detection

    Science.gov (United States)

    2013-06-01

    were grown using elemental mercury (Hg), cadmium (Cd), and selenium (Se) sources. The beam equiva- lent pressure ( BEP ) emanating from all sources was...flux), the BEP measured for the cracker source was found to vary with the cracking zone temperature, tracking with the data found in Ref. 7. This sug...The Se BEP measured for the typical cracking zone temperature of 800 C was found to be close to a factor of two lower than at the typical effusion cell

  17. Transcriptomic changes during maize roots development responsive to Cadmium (Cd) pollution using comparative RNAseq-based approach.

    Science.gov (United States)

    Peng, Hua; He, Xiujing; Gao, Jian; Ma, Haixia; Zhang, Zhiming; Shen, Yaou; Pan, Guangtang; Lin, Haijian

    2015-09-04

    The heavy metal cadmium (Cd), acts as a widespread environmental contaminant, which has shown to adversely affect human health, food safety and ecosystem safety in recent years. However, research on how plant respond to various kinds of heavy metal stress is scarcely reported, especially for understanding of complex molecular regulatory mechanisms and elucidating the gene networks of plant respond to Cd stress. Here, transcriptomic changes during Mo17 and B73 seedlings development responsive to Cd pollution were investigated and comparative RNAseq-based approach in both genotypes were performed. 115 differential expression genes (DEGs) with significant alteration in expression were found co-modulated in both genotypes during the maize seedling development; of those, most of DGEs were found comprised of stress and defense responses proteins, transporters, as well as transcription factors, such as thaumatin-like protein, ZmOPR2 and ZmOPR5. More interestingly, genotype-specific transcriptional factors changes induced by Cd stress were found contributed to the regulatory mechanism of Cd sensitivity in both different genotypes. Moreover, 12 co-expression modules associated with specific biological processes or pathways (M1 to M12) were identified by consensus co-expression network. These results will expand our understanding of complex molecular mechanism of response and defense to Cd exposure in maize seedling roots. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Gamma Irradiation Synthesis and Influence the Optical and Thermal Properties of Cadmium Sulfide (CdS/Poly (Vinyl Pyrolidone Nanocomposites

    Directory of Open Access Journals (Sweden)

    Shawkat S. Gasaymeh

    2010-01-01

    Full Text Available Problem statement: Gamma irradiation has been successfully used to prepare a spherical cadmium sulfide CdS/Poly Vinylpyrolidone (PVP quantum dots nanoparticles with enhancement of their optical band gap energy and thermal properties at room temperature and under ambient pressure. Sodium thiosulfate was used as a sulfur source in an aqueous solution. The formation of lower band gap energy of CdS/PVP nanoparticles and thermal stability can be controlled by using different irradiation doses. TEM images showed that the CdS/PVP particle size tends to be smaller and with better distribution as irradiation dose increases. Approach: Gamma (γ irradiation offered many advantages for the preparation of metal nanoparticles by producing large number of hydrated electrons during γ-ray irradiation, which can reduce the metal ions to zero valiant metal particles. Results: CdS/PVP nanoparticles were successfully prepared in one-step by γ-irradiation technique in an aqueous system at room temperature and under ambient pressure. The particle size was found to be less than 10 nm based on the Transmission Electron Microscopy (TEM that depended on the irradiation doses value, which showed a well distribution with a controlled size as doses change. The presence of PVP polymer was considered an important reason that influenced the shape and the distribution of those nanoparticles. The optical band gap energy of those nanoparticles was calculated by using the UV-VIS absorption spectra. Thermal analysis TGA showed that the composite had a higher degradation temperature than the PVP alone. A possible mechanism of the formation of cadmium sulfide by irradiation system was proposed. Conclusion: This result indicated that CdSO4 can effectively dope PVP and enhance the optical and thermal properties. In addition, γ-irradiation is an effective technique for preparing inorganic/organic nanocomposites.

  19. Effect of surface fields on the dynamic resistance of planar HgCdTe mid-wavelength infrared photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    He, Kai; Wang, Xi; Zhang, Peng; Chen, Yi-Yu [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Song-Min; Xie, Xiao-Hui; Lin, Chun, E-mail: chun-lin@mail.sitp.ac.cn; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao, E-mail: qinyao@mail.sitp.ac.cn [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Yang [Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-05-28

    This work investigates the effect of surface fields on the dynamic resistance of a planar HgCdTe mid-wavelength infrared photodiode from both theoretical and experimental aspects, considering a gated n-on-p diode with the surface potential of its p-region modulated. Theoretical models of the surface leakage current are developed, where the surface tunnelling current in the case of accumulation is expressed by modifying the formulation of bulk tunnelling currents, and the surface channel current for strong inversion is simulated with a transmission line method. Experimental data from the fabricated devices show a flat-band voltage of V{sub FB}=−5.7 V by capacitance-voltage measurement, and then the physical parameters for bulk properties are determined from the resistance-voltage characteristics of the diode working at a flat-band gate voltage. With proper values of the modeling parameters such as surface trap density and channel electron mobility, the theoretical R{sub 0}A product and corresponding dark current calculated from the proposed model as functions of the gate voltage V{sub g} demonstrate good consistency with the measured values. The R{sub 0}A product remarkably degenerates when V{sub g} is far below or above V{sub FB} because of the surface tunnelling current or channel current, respectively; and it attains the maximum value of 5.7×10{sup 7} Ω · cm{sup 2} around the transition between surface depletion and weak inversion when V{sub g}≈−4 V, which might result from reduced generation-recombination current.

  20. Bioaccumulation of arsenic, cadmium, mercury, lead and selenium in the benthic and pelagic food chain of Lake Baikal

    OpenAIRE

    Leeves, Sara Ann

    2011-01-01

    Increased anthropogenic release of potentially toxic trace elements such as arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb) and selenium (Se) into freshwater ecosystems over the past century has caused much concern. These elements are well known toxicants in aquatic ecosystems and may exert toxic effects even if present at relatively low concentrations in organisms. In this study, bioaccumulation of As, Cd, Hg, Pb and Se in the pelagic and benthic food chain of Lake Baikal have been inves...

  1. Fabrication and application of a new modified electrochemical sensor using nano-silica and a newly synthesized Schiff base for simultaneous determination of Cd{sup 2+}, Cu{sup 2+} and Hg{sup 2+} ions in water and some foodstuff samples

    Energy Technology Data Exchange (ETDEWEB)

    Afkhami, Abbas, E-mail: afkhami@basu.ac.ir [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Soltani-Felehgari, Farzaneh; Madrakian, Tayyebeh; Ghaedi, Hamed [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Rezaeivala, Majid [Department of Chemical Engineering, Hamedan University of Technology, Hamedan (Iran, Islamic Republic of)

    2013-04-10

    Highlights: ► A new modified electrochemical sensor was constructed and used. ► A new Schiff base coated nano-silica was used as modifier. ► The electrochemical properties of electrode were studied. ► This modifier enhanced the electrochemical properties of electrode. ► The electrode was used for simultaneous determination of Cd{sup 2+}, Cu{sup 2+} and Hg{sup 2+} ions. -- Abstract: A new chemically modified carbon paste electrode was constructed and used for rapid, simple, accurate, selective and highly sensitive simultaneous determination of cadmium, copper and mercury using square wave anodic stripping voltammetry (SWASV). The carbon paste electrode was modified by N,N′-bis(3-(2-thenylidenimino)propyl)piperazine coated silica nanoparticles. Compared with carbon paste electrode, the stripping peak currents had a significant increase at the modified electrode. Under the optimized conditions (deposition potential, −1.100 V vs. Ag/AgCl; deposition time, 60 s; resting time, 10 s; SW frequency, 25 Hz; pulse amplitude, 0.15 V; dc voltage step height, 4.4 mV), the detection limit was 0.3, 0.1 and 0.05 ng mL{sup −1} for the determination of Cd{sup 2+}, Cu{sup 2+} and Hg{sup 2+}, respectively. The complexation reaction of the ligand with several metal cations in methanol was studied and the stability constants of the complexes were obtained. The effects of different cations and anions on the simultaneous determination of metal ions were studied and it was found that the electrode is highly selective for the simultaneous determination of Cd{sup 2+}, Cu{sup 2+} and Hg{sup 2+}. Furthermore, the present method was applied to the determination of Cd{sup 2+}, Cu{sup 2+} and Hg{sup 2+} in water and some foodstuff samples.

  2. Computer optimization of multispectral solar cells based on GaAs Hg{sub 1-x}Cd{sub x}Te

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, D.; Esteve, D. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France); Rouhani, D. [Toulouse-3 Univ., 31 (France); Sylla, A.; Kouadja, K. [Abidjan Univ. (Cote d`Ivoire)

    1995-12-31

    The performances of the monolithic two solar cells tandem is studied. The geometrical and physical parameters of the two cells connected in series are determined for the optimal operation of the device. The chemical composition of the infra red sensitive Hg{sub 1-x}Cd{sub x}Te solar cell is for x = 0.53 with an energy gap of 0.6 eV. The maximum efficiency of the tandem under AM1 solar radiation has been found to be 30 % with contributions of 25 % and 5% for the GaAs and Hg{sub 1-w}Cd{sub x}Te solar cells, respectively. However, sophisticated technologies are needed to achieve this efficiency. (author) 12 refs.

  3. Computer optimization of multispectral solar cells based on GaAs Hg{sub 1-x}Cd{sub x}Te

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, D.; Esteve, D. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France); Rouhani, D. [Toulouse-3 Univ., 31 (France); Sylla, A.; Kouadja, K. [Abidjan Univ. (Cote d`Ivoire)

    1995-12-31

    The performances of the monolithic two solar cells tandem is studied. The geometrical and physical parameters of the two cells connected in series are determined for the optimal operation of the device. The chemical composition of the infra red sensitive Hg{sub 1-x}Cd{sub x}Te solar cell is for x = 0.53 with an energy gap of 0.6 eV. The maximum efficiency of the tandem under AM1 solar radiation has been found to be 30 % with contributions of 25 % and 5% for the GaAs and Hg{sub 1-w}Cd{sub x}Te solar cells, respectively. However, sophisticated technologies are needed to achieve this efficiency. (author) 12 refs.

  4. Preparation of cross-linked magnetic chitosan-phenylthiourea resin for adsorption of Hg(II), Cd(II) and Zn(II) ions from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Monier, M., E-mail: monierchem@yahoo.com [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abdel-Latif, D.A. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer Chitosan was chemically modified through the reaction with phenylisothiocyanate. Black-Right-Pointing-Pointer The modified chitosan-phenylthiourea cross-linked with formaldehyde in presence of magnetite to produce modified magnetic resin. Black-Right-Pointing-Pointer The resulted resin characterized by various instrumental methods. Black-Right-Pointing-Pointer The resin was applied to remove Hg{sup 2+}, Cd{sup 2+} and Zn{sup 2+} from aqueous solutions. - Abstract: In this study, cross-linked magnetic chitosan-phenylthiourea (CSTU) resin were prepared and characterized by means of FTIR, {sup 1}H NMR, SEM high-angle X-ray diffraction (XRD), magnetic properties and thermogravimetric analysis (TGA). The prepared resin were used to investigate the adsorption properties of Hg(II), Cd(II) and Zn(II) metal ions in an aqueous solution. The extent of adsorption was investigated as a function of pH and the metal ion removal reached maximum at pH 5.0. Also, the kinetic and thermodynamic parameters of the adsorption process were estimated. These data indicated that the adsorption process is exothermic and followed the pseudo-second-order kinetics. Equilibrium studies showed that the data of Hg(II), Cd(II) and Zn(II) adsorption followed the Langmuir model. The maximum adsorption capacities for Hg(II), Cd(II) and Zn(II) were estimated to be 135 {+-} 3, 120 {+-} 1 and 52 {+-} 1 mg/g, which demonstrated the high adsorption efficiency of CSTU toward the studied metal ions.

  5. Magnetotransmission of unpolarized infrared radiation in Hg1 - x Cd x Cr2Se4 (0 ≤ x ≤ 1) single crystals studied using the voigt geometry

    Science.gov (United States)

    Sukhorukov, Yu. P.; Telegin, A. V.; Bebenin, N. G.; Patrakov, E. I.; Naumov, S. V.; Fedorov, V. A.; Menshchikova, T. K.

    2013-11-01

    The features characterizing the behavior of magnetotransmission in Hg1 - x Cd x Cr2Se4 single crystals are studied using natural light in the infrared spectral range. The relation between the changes in the magneto-optical properties and in the electron band structure is found. It is shown that the most significant changes in the magnetotransmission spectrum and the band structure occur within the 0.1 < x < 0.25 range.

  6. Concentración de Hg, Pb, Cd, Cr y As en hígado de Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) capturado en Veracruz, México

    OpenAIRE

    Mendoza Díaz, Fernando; Serrano, Arturo; CUERVO LÓPEZ, LILIANA; López Jiménez, Alejandra; Galindo, José A.; Basañez Muñoz, Agustín

    2013-01-01

    Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) captured in Veracruz, Mexico. Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study ...

  7. Transcriptomic changes during maize roots development responsive to Cadmium (Cd) pollution using comparative RNAseq-based approach

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Hua [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Sichuan Tourism College, Chengdu, 610000, Sichuan (China); He, Xiujing [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Gao, Jian [Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing (China); Ma, Haixia; Zhang, Zhiming; Shen, Yaou [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Pan, Guangtang, E-mail: pangt@sicau.edu.cn [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Lin, Haijian, E-mail: linhj521@gmail.com [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China)

    2015-09-04

    The heavy metal cadmium (Cd), acts as a widespread environmental contaminant, which has shown to adversely affect human health, food safety and ecosystem safety in recent years. However, research on how plant respond to various kinds of heavy metal stress is scarcely reported, especially for understanding of complex molecular regulatory mechanisms and elucidating the gene networks of plant respond to Cd stress. Here, transcriptomic changes during Mo17 and B73 seedlings development responsive to Cd pollution were investigated and comparative RNAseq-based approach in both genotypes were performed. 115 differential expression genes (DEGs) with significant alteration in expression were found co-modulated in both genotypes during the maize seedling development; of those, most of DGEs were found comprised of stress and defense responses proteins, transporters, as well as transcription factors, such as thaumatin-like protein, ZmOPR2 and ZmOPR5. More interestingly, genotype-specific transcriptional factors changes induced by Cd stress were found contributed to the regulatory mechanism of Cd sensitivity in both different genotypes. Moreover, 12 co-expression modules associated with specific biological processes or pathways (M1 to M12) were identified by consensus co-expression network. These results will expand our understanding of complex molecular mechanism of response and defense to Cd exposure in maize seedling roots. - Highlights: • Transcriptomic changes responsive to Cd pollution using comparative RNAseq-based approach. • 115 differential expression genes (DEGs) were found co-modulated in both genotypes. • Most of DGEs belong to stress and defense responses proteins, transporters, transcription factors. • 12 co-expression modules associated with specific biological processes or pathways. • Genotype-specific transcriptional factors changes induced by Cd stress were found.

  8. Opto-electronic Properties of Mid-Wavelength: n Type II InAs/InAs1- x Sb x and Hg1- x Cd x Te

    Science.gov (United States)

    De Wames, Roger E.

    2016-09-01

    There is significant interest in mid-wavelength type II strained layer superlattices (SLSs) and HgCdTe material systems for background limited performance, operating at significantly higher temperature, T ≥ 150 K, than InSb, T ≈ 80-90 K. A precise knowledge of the electronic and optical properties of these materials is desirable since they determine detector performance and are needed for input parameters in self-consistent physics-based predictive models. Recently, data on the optical absorption coefficient, and the hole minority carrier lifetime has become available, suggesting that in the extrinsic region the limiting recombination processes in mid-wavelength type II Ga-free SLSs are radiative and Shockley-Read-Hall (SRH). These findings provide the opportunity for comparisons with mid-wavelength HgCdTe. The comparisons show that the radiative recombination coefficients are similar; however, the SRH lifetime limited to 9 μs for the SLS implies that the dark current density is expected to be limited by bulk generation-recombination (G-R) SRH processes for temperatures below 160 K; hence requiring heterojunction designs to suppress the G-R dark currents and be diffusion limited. Mid-wavelength infrared HgCdTe photodiodes are shallow p+n photovoltaic devices and because of the very long SRH hole lifetime are diffusion radiatively limited photodiodes down to 80 K.

  9. ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2011-08-01

    Full Text Available The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm, 2.91 eV (426 nm and 4.27 eV (290 nm for the ZnS, CdS and HgS samples respectively.

  10. Synthesis, characterization, DFT and biological studies of isatinpicolinohydrazone and its Zn(II), Cd(II) and Hg(II) complexes

    Science.gov (United States)

    El-Gammal, O. A.; Rakha, T. H.; Metwally, H. M.; Abu El-Reash, G. M.

    2014-06-01

    Isatinpicolinohydrazone (H2IPH) and its Zn(II), Cd(II) and Hg(II) complexes have been synthesized and investigated using physicochemical techniques viz. IR, 1H NMR, 13C NMR, UV-Vis spectrometric methods and magnetic moment measurements. The investigation revealed that H2IPH acts as binegative tetradentate in Zn(II), neutral tridentate in Cd(II) and as neutral bidentate towards Hg(II) complex. Octahedral geometry is proposed for all complexes. The bond length, bond angle, chemical reactivity, energy components (kcal/mol), binding energy (kcal/mol) and dipole moment (Debyes) for all the title compounds were evaluated by DFT and also MEP for the ligand is shown. Theoretical infrared intensities of H2IPH and also the theoretical electronic spectra of the ligand and its complexes were calculated. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The in vitro antibacterial studies of the complexes proved them as growth inhibiting agents. The DDPH antioxidant of the compounds have been screened. Antitumor activity, carried out in vitro on human mammary gland (breast) MCF7, have shown that Hg(II) complex exhibited potent activity followed by Zn(II), Cd(II) complexes and the ligand.

  11. Preparation of cross-linked magnetic chitosan-phenylthiourea resin for adsorption of Hg(II), Cd(II) and Zn(II) ions from aqueous solutions.

    Science.gov (United States)

    Monier, M; Abdel-Latif, D A

    2012-03-30

    In this study, cross-linked magnetic chitosan-phenylthiourea (CSTU) resin were prepared and characterized by means of FTIR, (1)H NMR, SEM high-angle X-ray diffraction (XRD), magnetic properties and thermogravimetric analysis (TGA). The prepared resin were used to investigate the adsorption properties of Hg(II), Cd(II) and Zn(II) metal ions in an aqueous solution. The extent of adsorption was investigated as a function of pH and the metal ion removal reached maximum at pH 5.0. Also, the kinetic and thermodynamic parameters of the adsorption process were estimated. These data indicated that the adsorption process is exothermic and followed the pseudo-second-order kinetics. Equilibrium studies showed that the data of Hg(II), Cd(II) and Zn(II) adsorption followed the Langmuir model. The maximum adsorption capacities for Hg(II), Cd(II) and Zn(II) were estimated to be 135 ± 3, 120 ± 1 and 52 ± 1 mg/g, which demonstrated the high adsorption efficiency of CSTU toward the studied metal ions.

  12. Adsorption Study of Pb(II, Cd(II, Hg(II And Cr(III Onto Calix[4]Resorcinarene Derivative

    Directory of Open Access Journals (Sweden)

    Chairil Anwar

    2016-11-01

    Full Text Available In this study, the removal of several heavy metal ions of Pb(II, Cd(II, Hg(II and Cr(III from aqueous medium via sorption process onto calix[4]resorcinarene derivative was investigated. The used adsorbent was highly oxygenated calix[4]resorcinarene namely C-4-hydroxyphenylcalix[4]resorcinarene. Several adsorption parameters were studied including pH, adsorbent dosage, interaction time as well as the kinetic studies. While the maximum removals of Pb(II, Cd(II and Hg(II were observed in pH 5, the removal of Cr(III reached the maximum value at pH 6. The optimum adsorbent dosages for Pb(II, Hg(II and Cr(III were 0.025 g, whereas that for Cd(II was 0.05 g. The kinetic data were evaluated by using three kinetic models of first order model of Santosa, pseudo-first order of Lagergren and pseudo-second order of Ho. The results showed that the adsorption of these metal ions could be well described with Ho's pseudo-first order model.

  13. Pengaruh Waktu Perendaman dan Konsentrasi Karboksimetil Kitosan untuk Menurunkan Kandungan Logam Berat Hg, Cd, Dan Pb Pada Kerang Hijau (Perna Viridis Linn.

    Directory of Open Access Journals (Sweden)

    Jovita Tri Murtini

    2008-06-01

    Full Text Available ABSTRAK Penelitian telah dilakukan untuk mengetahui pengaruh waktu perendaman dan konsentrasi karboksimetil kitosan larut air (KMK terhadap kandungan logam berat Hg, Cd, dan Pb pada daging kerang hijau (Perna viridis Linn.. Perlakuan perendaman larutan karboksimetil kitosan menggunakan konsentrasi 0; 0,5; 1; dan 1,5% dengan lama perendaman 1, 2, dan 3 jam. Hasil penelitian menunjukkan bahwa perlakuan yang paling efektif untuk penurunan logam Hg adalah perendaman dengan larutan KMK 0,5% selama 1 jam, sedangkan perlakuan yang paling efektif untuk penurunan Pb adalah perendaman dengan larutan KMK 0,5% selama 3 jam. Hasil penelitian juga menunjukkan bahwa KMK tidak efektif untuk menurunkan Cd pada kerang hijau. Analisis sidik ragam menunjukkan tidak ada interaksi antara konsentrasi KMK dengan lama perendaman yang dapat menurunkan kandungan Hg dan Cd, tetapi terdapat interaksi yang sangat nyata antara konsentrasi KMK dan lama perendaman untuk menurunkan kandungan Pb. Perendaman dalam akuades (KMK 0% sudah dapat menurunkan kandungan logam berat dalam kerang hijau, diduga karena terjadinya leaching dari senyawa organik yang berikatan dengan logam berat.

  14. Determination of charge-carrier diffusion length in the photosensing layer of HgCdTe n-on-p photovoltaic infrared focal plane array detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vishnyakov, A. V.; Stuchinsky, V. A., E-mail: stuchin@isp.nsc.ru; Brunev, D. V.; Zverev, A. V.; Dvoretsky, S. A. [Institute of Semiconductor Physics, Russian Academy of Science, Siberian Division, 13, Acad. Lavrent' ev Avenue, Novosibirsk 630090 (Russian Federation)

    2014-03-03

    In the present paper, we propose a method for evaluating the bulk diffusion length of minority charge carriers in the photosensing layer of photovoltaic focal plane array (FPA) photodetectors. The method is based on scanning a strip-shaped illumination spot with one of the detector diodes at a low level of photocurrents j{sub ph} being registered; such scanning provides data for subsequent analysis of measured spot-scan profiles within a simple diffusion model. The asymptotic behavior of the effective (at j{sub ph} ≠ 0) charge-carrier diffusion length l{sub d} {sub eff} as a function of j{sub ph} for j{sub ph} → 0 inferred from our experimental data proved to be consistent with the behavior of l{sub d} {sub eff} vs j{sub ph} as predicted by the model, while the obtained values of the bulk diffusion length of minority carriers (electrons) in the p-HgCdTe film of investigated HgCdTe n-on-p FPA photodetectors were found to be in a good agreement with the previously reported carrier diffusion-length values for HgCdTe.

  15. Synthesis, Spectroscopy, Theoretical, and Electrochemical Studies of Zn(II, Cd(II, and Hg(II Azide and Thiocyanate Complexes of a New Symmetric Schiff-Base Ligand

    Directory of Open Access Journals (Sweden)

    Morteza Montazerozohori

    2013-01-01

    Full Text Available Synthesis of zinc(II/cadmium(II/mercury(II thiocyanate and azide complexes of a new bidentate Schiff-base ligand (L with general formula of MLX2 (M = Zn(II, Cd(II, and Hg(II in ethanol solution at room temperature is reported. The ligand and metal complexes were characterized by using ultraviolet-visible (UV-visible, Fourier transform infrared (FT-IR, 1H- and 13C-NMR spectroscopy and physical characterization, CHN analysis, and molar conductivity. 1H- and 13C-NMR spectra have been studied in DMSO-d6. The reasonable shifts of FT-IR and NMR spectral signals of the complexes with respect to the free ligand confirm well coordination of Schiff-base ligand and anions in an inner sphere coordination space. The conductivity measurements as well as spectral data indicated that the complexes are nonelectrolyte. Theoretical optimization on the structure of ligand and its complexes was performed at the Becke’s three-parameter hybrid functional (B3 with the nonlocal correlation of Lee-Yang-Parr (LYP level of theory with double-zeta valence (LANL2DZ basis set using GAUSSIAN 03 suite of program, and then some theoretical structural parameters such as bond lengths, bond angles, and torsion angles were obtained. Finally, electrochemical behavior of ligand and its complexes was investigated. Cyclic voltammograms of metal complexes showed considerable changes with respect to free ligand.

  16. [Phytoavailability and chemical speciation of cadmium in different Cd-contaminated soils with crop root return].

    Science.gov (United States)

    Zhang, Jing; Yu, Ling-Ling; Xin, Shu-Zhen; Su, De-Chun

    2013-02-01

    Pot experiments were conducted under greenhouse condition to investigate the effects of crop root return on succeeding crops growth, Cd uptake and soil Cd speciation in Cd-contaminated soil and artificial Cd-contaminated soil. The results showed that the amount of root residue returned to soil by corn and kidney bean growth successive for 3 times was 0.4%-1.1%. The Cd returned to soil by root residue was 1.3%-3.5% to the total soil Cd. There was no significant difference in the shoot dry weights of winter wheat and Chinese cabbage grown on the 2 Cd-contaminated soils with and without root return. While Cd concentration of Chinese cabbage increased significantly in the Cd-contaminated soil with corn or kidney bean root return. Light fraction of soil organic matter increased with root return in both of the Cd-contaminated soils. The percentage of Cd in the light fraction of soil organic matter increased with root return in the artificial Cd-contaminated soil. Soil carbonates-bound Cd concentration decreased significantly with corn root return in the Cd-contaminated soil. Soil exchangeable Cd concentration decreased and soil Fe-Mn oxide-bound Cd concentration increased significantly with kidney bean root return in the artificial Cd-contaminated soil.

  17. Calculation of critical loads for cadmium, lead and mercury; background document to a mapping manual on critical loads of cadmium, lead and mercury

    NARCIS (Netherlands)

    Vries, de W.; Schütze, G.; Lofts, S.; Tipping, E.; Meili, M.; Römkens, P.F.A.M.; Groenenberg, J.E.

    2005-01-01

    This report on heavy metals provides up-to-date methodologies to derive critical loads for the heavy metals cadmium (Cd), lead (Pb) and mercury (Hg) for both terrestrial and aquatic ecosystems. It presents background information to a Manual on Critical Loads for those metals. Focus is given to the m

  18. Macro-loading Effects in Inductively Coupled Plasma Etched Mercury Cadmium Telluride

    Science.gov (United States)

    Apte, Palash; Rybnicek, Kimon; Stoltz, Andrew

    2016-09-01

    This paper reports the effect of macro-loading on mercury cadmium telluride (Hg1- x Cd x Te) and Photoresist (PR) etched in an inductively coupled plasma (ICP). A significant macro-loading effect is observed, which affects the etch rates of both PR and Hg1- x Cd x Te. It is observed that the exposed silicon area has a significant effect on the PR etch rate, but not on the Hg1- x Cd x Te etch rate. It is also observed that the exposed Hg1- x Cd x Te area has a significant effect on the etch rate of the PR, but the exposed PR area does not seem to have an effect on the Hg1- x Cd x Te etch rate. Further, the exposed Hg1- x Cd x Te area is shown to affect the etch rate of the Hg1- x Cd x Te, but there does not seem to be a similar effect for the exposed PR area on the etch rate of the PR. Since the macro-loading affects the selectivity significantly, this effect can cause significant problems in the etching of deep trenches. A few techniques to reduce the effect of macro-loading on the etch rates of the PR and Hg1- x Cd x Te are listed, herein.

  19. 广东贵屿土壤Cd、Hg潜在威胁评价%Potential Threat of Cd, Hg in Soil of Guiyu, Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    罗杰; 温汉辉; 吴丽霞; 游远航; 欧阳春飞

    2012-01-01

    通过表层土壤、深层土壤、水稻样品及水样的采取与分析,结果表明,水俣病的元凶Hg在广东省贵屿镇土壤中具有极高的富集系数,易在酸性条件下向有效形态转化的弱有机结合态Hg占全Hg的17.74%;痛痛病的元凶Cd在部分土壤中的含量已超过环境承受的极限,且最易与生命体发生作用的水溶态Cd和离子交换态Cd占全Cd的比例高达16.2%.Hg、Cd的块金系数均大于70%,具明显的表层富集特征,与家电拆解作坊表层土壤重金属元素同源性较好,说明Cd、Hg的分布、富集受人类活动影响强烈,其对生态环境和居民健康存在极强的潜在威胁,在特定条件下有可能引发各类地方病.%Guiyu is located in the junction of Chaoyang, Puning and Jieyang. It is a famous "first town of e-lectronic-waste". Electronic-waste in the local has caused serious environmental pollution and damaged the health of residents. The research showed the Hg which is the main cause of Minamata disease has a high soil enrichment factor in the town. The weak organic-bound Cd which could easily transform to Hg under acidic conditions accounts for 17. 74% of the total content. Cd is the main cause of Itai-itai disease. The content of Cd in some soil has exceeded the environmental limit. The content of water-soluble Cd and ion-exchange Cd which can most easily influence living body accounts for 16. 2% of the total content. The nugget coefficient of Hg and Cd were more than 70%, which has a significant surface enrichment characteristics and has good homology with heavy metals in surface soil of dismantling workshops. This showed that the distribution and enrichment characteristics of Cd and Hg are affected by human activities significantly, and existence of a potential threat to environment and health of residents under certain conditions may lead to endemic diseases.

  20. Ellipsometric Analysis of Cadmium Telluride Films’ Structure

    Directory of Open Access Journals (Sweden)

    Anna Evmenova

    2015-01-01

    Full Text Available Ellipsometric analysis of CdTe films grown on Si and CdHgTe substrates at the “hot-wall” epitaxy vacuum setup has been performed. It has been found that ellipsometric data calculation carried out by using a simple one-layer film model leads to radical distortion of optical constants spectra: this fact authenticates the necessity to attract a more complicated model that should include heterogeneity of films. Ellipsometric data calculation within a two-layer film model permitted to conclude that cadmium telluride films have an outer layer that consists of the three-component mixture of CdTe, cavities, and basic matter oxide. Ratio of mixture components depends on the time of deposition, that is, on the film thickness. The inner layer consists of cadmium telluride.

  1. Sellmeier and thermo-optic dispersion formulas for CdGa2S4 and their application to the nonlinear optics of Hg1-xCdxGa2S4

    Science.gov (United States)

    Kato, Kiyoshi; Umemura, Nobuhiro; Petrov, Valentin

    2017-03-01

    This paper reports the Sellmeier and thermo-optic dispersion formulas for CdGa2S4 that provide excellent reproduction of the temperature-dependent phase-matching conditions in Hg0.35Cd0.65Ga2S4 and Hg0.51Cd0.49Ga2S4 for second-harmonic generation (SHG) and sum-frequency generation (SFG) in the 0.897-10.5910 μm spectral range coupled with Sellmeier and thermo-optic dispersion formulas for HgGa2S4 presented in our previous papers (Kato et al., 2016 [1]; Umemura et al., 2012 [2]).

  2. KHELASI PLUMBUM (Pb DAN CADMIUM (Cd MENGGUNAKAN ASAM SITRAT PADA BIJI KEDELA (Chelation of Plumbum and Cadmium by Citric acid in Soybean Seeds

    Directory of Open Access Journals (Sweden)

    Sapto Priyadi

    2014-02-01

    Full Text Available A study on the chelation of plumbum and cadmium by citric acid in soybean seeds, it was aimed to identify the effect of chelation treatment (chelating ratio, time contact and seeds condition on plumbum reduction and cadmium in soybean seeds. A factors of research covering 1st chelating ratio (citric acid/”C” consisting of three (1, 2 and 3 grams of citric acid; 2nd the time contact (“D” consisting of three (90, 120 and 180 minutes and the 3rd factors is condition of the seeds (“E” consisting of three standard (whole qualify e.i. passing sieve of 0.3 inch and restrained at 0.2 inch, ruptured e.i. restrained for sieve at 10 mesh, and flour qualify for pass for sieves 50 mesh. The result showed that the combination of three factors were able to reduce Cd maximaly (non detected/detect limit 0.01 ppm. Reduction Pb maximaly (non detected /detect limit 0.09 ppm occured in treatment C1D1E1, C1D1E2, C1D2E1, C1D2E2, C1D2E2, C2D1E1, C2D1E2, C2D2E1, C2D3E1, C2D3E2, C3D1E1 and C3D2E1. A combination of citric acid chelation (C with the time contact (D showing significant difference and both showed interactions, the reduction of the highest was C1D1 treatment. A combination of citric acid chelation (C with the condition of the nut (E showed significant difference and both no interaction, the reduction of the highest was C2E1 treatment. The combination between the time of contact (D with the condition of the seed (E showed significant difference and both no interaction, the reduction of the highest were D1E1 and D2E1 treatments. Keywords: chelation, plumbum, cadmium and soybean   ABSTRAK Telah dilakukan penelitian tentang khelasi plumbum (pb dan cadmium (cd menggunakan asam sitrat pada biji kedelai, dengan tujuan untuk mengetahui pengaruh faktor perlakuan khelasi (ratio pengkhelat, waktu kontak dan kondisi biji dalam mereduksi Pb dan Cd pada biji kedelai. Faktor penelitian meliputi 1 rasio pengkhelat (asam sitrat/C yang terdiri dari tiga taraf (1

  3. ROIC with on-chip sigma-delta AD converter for HgCdTe e-APD FPA

    Science.gov (United States)

    Chen, Guoqiang; Zhang, Junling; Wang, Pan; Zhou, Jie; Gao, Lei; Ding, Ruijun

    2013-10-01

    HgCdTe electron injection avalanche photodiodes (e-APDs) work at linear mode. A weak optical current signal is amplified orders of magnitude due to the internal avalanche mechanism and it has been demonstrated to be one of the most promising methods to focal-plane arrays (FPAs) for low-flux like hyper-spectral imaging and high-speed applications such as active imaging. This paper presents the design of a column-shared ADC for cooled e-APDs FPA. Designing a digital FPA requires fulfilling very stringent requirements in terms of power consumption, silicon area and speed. Among the various ADC architectures sigma-delta conversion is a promising solution for high-performance and medium size FPA such as 128×128. The performance of Sigma-delta ADC rather relies on the modulator structure which set over-sampling and noise shaping characteristics than on critical analog circuits. This makes them quite robust and flexible. A multistage noise shaping (MASH) 2-1 single bit architecture sigma-delta conversion with switched-capacitor circuits is designed for column-shared ADC, which is implanted in the GLOBALFOUNDRIES 0.35um CMOS process with 4-poly and 4-metal on the basis of a 100um pixel pitch. It operates under 3.3V supply and the output range of the quantizer is 2V. A quantization noise subtraction circuit in modulator is designed to subtract the quantization noise of first-stage modulator. The quantization noise of the modulator is shaped by a high-pass filter. The silicon area and power consumption are mainly determined by the decimation low pass filter. A cascaded integrator-comb (CIC) filter is designed as the digital decimator filter. CIC filter requires no multipliers and use limited storage thereby leading to more economical hardware implementation. The register word length of the filter in each stage is carefully dimensioned in order to minimize the required hardware. Furthermore, the digital filters operate with a reduced supply voltage to 1.5V. Simulation

  4. Translocation of mercury and cadmium into the fruiting bodies of six higher fungi

    Energy Technology Data Exchange (ETDEWEB)

    Brunnert, H.; Zadrazil, F.

    1983-01-01

    The species- and metal-specific translocation of cadmium and mercury from the substrate to the fruiting bodies of 6 higher fungi has been investigated. The 6 species differed greatly in their ability to translocate cadmium and mercury. The highest translocation rates displayed Pleurotus flabellatus: 75.0% of the applied cadmium and 38.5% of the mercury could be recovered from the fruiting bodies. High translocation rates also found with Pleurotus ostreatus (19.3 and 38.5% for cadmium and mercury, respectively). This compares with only 1.27% of cadmium and 8.42% of mercury in Agaricus bisporus or 3.71% of cadmium and 3.63% of mercury in Pleurotus sajor caju. For Agaricus bisporus it was shown that there was proportionality of translocation over a 1:10 concentration range. In 4 out of 6 species there was a tendency towards higher heavy metal contents in later crops, when calculated on the basis of ..mu..g/g of dry fruiting body. In 4 out of 6 more mercury than cadmium was translocated into the fruiting bodies, the Cd/Hg ratios being 6.6, 2.0, 5.6, and 3.2, respectively. In Pleurotus sajor caju the ratio was about 1. Only in Pleurotus flabellatus more cadmium than mercury was found in the fruiting bodies (Cd/Hg ratio 0.65).

  5. Effect of lead, mercury and cadmium on a sulphate-reducing bacterium

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Sathe, V.; Chandramohan, D.

    Pollution 67 (1990) 361-374 Effect of Lead, Mercury and Cadmium on a Sulphate-Reducing Bacterium P. A. Loka Bharathi, V. Sathe & D. Chandramohan National Institute of Oceanography, Dona Paula, Goa-403004, India (Received 9 March 1990; revised version... oftoxicity to growth of these metal salts in a lactate-based medium at 50 J1g mr 1 concentrations was Cd> Pb> Hg and to respiration Pb> Cd> Hg. Inhibitory concentrations (viz. 100 J1g mr 1 ofHgCl z and200 J1g mr 1 ofPb(N0 3 )z) hada stimulatory effect when...

  6. Cadmium sulfide nanowires for the window semiconductor layer in thin film CdS-CdTe solar cells.

    Science.gov (United States)

    Liu, Piao; Singh, Vijay P; Jarro, Carlos A; Rajaputra, Suresh

    2011-04-08

    Thin film CdS/CdTe heterojunction device is a leading technology for the solar cells of the next generation. We report on two novel device configurations for these cells where the traditional CdS window layer is replaced by nanowires (NW) of CdS, embedded in an aluminum oxide matrix or free-standing. An estimated 26.8% improvement in power conversion efficiency over the traditional device structure is expected, primarily because of the enhanced spectral transmission of sunlight through the NW-CdS layer and a reduction in the junction area/optical area ratio. In initial experiments, nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved.

  7. Self-Assembled Templates of Aromatic Pentapeptides for Synthesis of CdS Quantum-Dots to Detect the Trace Amounts of Hg(2+) in Aqueous Solutions.

    Science.gov (United States)

    Meng, Min; Dou, Yingying; Xu, Wenlong; Hao, Jingcheng

    2016-05-01

    Molecular self-assembly has become a popular tool to prepare nanomaterials with potential applications, such as ion-responsive detection of Hg(2+) in aqueous solutions. In this study, FFACD aromatic pentapeptides, whose N-terminuses were protected by carboxyl (Ac-FFACD) or a 9-fluorenylmethoxycarbonyl group (Fmoc-FFACD), were chosen as building blocks to produce nanostructures in solutions. Based on the preliminary determination of the critical aggregation concentration (CAC) of Ac-FFACD and Fmoc-FFACD aromatic pentapeptides in water, the order of magnitude of which is 10(-5) mol·L(-1), self-assembled spiral and networked nanowires can be easily obtained over a range of concentrations. These nanowires were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The self-assembled spiral and networked nanowires were designed to be used as templates for preparing CdS quantum dots (QDs) in-situ at room temperature. The peptide-functionalized, nanowire-encapsulated CdS QDs can be used for rapid, sensitive, and selective detection of trace amounts of mercuric ions (Hg(2+)) in aqueous solutions. This method enables rapid, linear detection (the linear correlation coefficients are 0.9972 of ΔF = 257.09 + 3.58 cHg(2+) for Ac-FFACD and 0.9994 of ΔF = 48.13 + 32.96 cHg(2+) for Fmoc-FFACD) with the Hg(2+) limit of detection at 300.85 ng·L(-1) and 32.09 ng·L(-1) for Ac-FFACD and Fmoc-FFACD, respectively. The supramolecular, self-assembled nanowires, fabricated from the two aromatic pentapeptides and having encapsulated QDs, exhibit superior properties attributable to the large loading capacity and the coordination sites of these peptides with Hg(2+). These structures can serve as novel Hg(2+) sensors and have possible applications for detection of various targets in scientific and engineering systems.

  8. Optimization of simultaneous electrochemical determination of Cd(II), Pb(II), Cu(II) and Hg(II) at carbon nanotube-modified graphite electrodes.

    Science.gov (United States)

    Pikna, L'ubomír; Heželová, Mária; Kováčová, Zuzana

    2015-01-01

    The health of the environment is worsening every day. Monitoring of potentially toxic elements and remediation of environmental pollution are necessary. Therefore, the research and development of simple, inexpensive, portable and effective sensors is important. Electrochemistry is a useful component of the field of environment monitoring. The present study focuses on evaluating and comparing three types of electrodes (PIGE, PIGE/MWCNT/HNO3 and PIGE/MWCNT/EDTA/HNO3) employed for the simultaneous electrochemical determination of four potentially toxic elements: Cd(II), Pb(II), Cu(II) and Hg(II). Cyclic voltammograms were measured in an acetate buffer. The LOD, LOQ, the standard and relative precisions of the method and a prediction intervals were calculated (according to the technical procedure DIN 32 645) for the three electrodes and for each measured element. The LOD for PIGE/CNT/HNO3 (the electrode with narrowest calculated prediction intervals) was 2.98 × 10(-7) mol L(-1) for Cd(II), 4.83 × 10(-7) mol L(-1) for Pb(II), 3.81 × 10(-7) mol L(-1) for Cu(II), 6.79 × 10(-7) mol L(-1) for Hg(II). One of the benefits of this study was the determination of the amount of Hg(II) in the mixture of other elements.

  9. Synthesis and structural characterization of dinuclear Cd2+, Hg2+ and Fe2+ complexes with neutral bi and tetradentate flexible pyrazole-based ligands

    Science.gov (United States)

    Beheshti, Azizolla; Lalegani, Arash; Behvandi, Fatemeh; Safaeiyan, Forough; Sarkarzadeh, Afsoon; Bruno, Giuseppe; Amiri Rudbari, Hadi

    2015-02-01

    Four new complexes of [Hg2Cl4(bpp)]n (1), [Hg2Cl4(tdmpp)] (2), [Cd2I4(tdmpp)] (3) and [Fe2Cl4(tdmpp)] (4) were prepared by using the neutral N-donor ligands 1,3-bis(3,5-dimethyl-1-pyrazolyl)propane (bpp) and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (tdmpp) with different flexibility and appropriate metal salts of Cd(II), Hg(II) and Fe(II) ions. These compounds were characterized by the infrared spectroscopy, elemental analysis and X-ray crystallography. Flexible ligands and non-covalent Csbnd H⋯Cl hydrogen bonds play a major role in the crystal packing of compounds 1, 2 and 4. In the two-dimensional non-covalent structure of 1, there are two distinctly different coordination modes for the mercury atoms. One mercury atom has pseudo-trigonal bipyramidal geometry and the other adopts a distorted tetrahedral environment. In the dinuclear structures of 2 and 4 the neutral molecules are linked together by the Csbnd H⋯Cl hydrogen bonds, forming an infinite one-dimensional zigzag chain structure. Compounds 2-4 are isostructural with each other.

  10. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits.

    Science.gov (United States)

    Wen, Hanjie; Zhu, Chuanwei; Zhang, Yuxu; Cloquet, Christophe; Fan, Haifeng; Fu, Shaohong

    2016-04-28

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ(114/110)Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ(114/110)Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

  11. Responses of different Chinese flowering cabbage (brassica parachinensis l.) cultivars to cadmium and lead exposure: screening for Cd + Pb pollution-safe cultivars

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Qiu; Yang, Zhongyi; Xin, Junliang; Yuan, Jiangang; Wang, Jianbing; Xin, Guorong [State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou (China); Wang, Yutao [Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, Guangdong (China)

    2011-11-15

    To reduce the potential risks of cadmium (Cd) and lead (Pb) entering the human food chain in vegetables, two pot experiments (Exp. 1 and Exp. 2) were carried out to screen for Cd and Pb pollution-safe cultivars (PSCs) of Chinese flowering cabbage (Brassica parachinensis L.). The three Cd treatments in Exp. 1 (0.114, 0.667, and 1.127 mg kg{sup -1}) showed that Chinese flowering cabbage could easily take up Cd from polluted soils, and there were wide variations in Cd accumulation among different cultivars. The Cd accumulation trait at cultivar level was rather stable under different soil Cd treatments. In Exp. 2, seven cultivars that had been shown in Exp. 1 to be typical high or low accumulators of Cd were selected and six Cd + Pb joint exposure treatments were applied to them. The results showed that there were similar trends of accumulation between Cd and Pb for the tested cultivars, but Pb accumulation by the species was much poorer than that of Cd. It was worth noting that an increase in soil Pb levels significantly (p < 0.01) depressed shoot Cd accumulation. Six cultivars were selected as Cd + Pb PSCs. This study showed that it is feasible to apply a PSC strategy in Chinese flowering cabbage cultivation, to cope with the Cd and Pb contamination commonly found in agricultural soils. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Genotype variations in accumulation of cadmium and lead in celery (Apium graveolens L.) and screening for low Cd and Pb accumulative cultivars

    Institute of Scientific and Technical Information of China (English)

    Kun ZHANG; Jianbing WANG; Zhongyi YANG; Guorong XIN; Jiangang YUAN; Junliang XIN; Charlie HUANG

    2013-01-01

    To help reduce risks of heavy metal pollution, two pot experiments were conducted to investigate the variations, transfer potential, and stability of Cadmium (Cd) and Lead (Pb) accumulations in celery (Apium graveolens L.) and to screen for low Cd and Pb accumulative cultivars. The maximum differences in shoot Cd concentration were 4.7-fold under low-Cd exposure and 3.3-fold under high-Cd exposure. These genotype variations in Cd accumulation are sufficiently large to help reduce Cd contamination risk in soil by using the Low-Cd-Accumulative genotypes. Cd accumulation of the Low-Cd-Accumulative genotypes is significantly positive correlated with Pb accumulation. Evidence obtained proves that Cd and Pb accumulations in celery are stable and genotype-dependent at the cultivar level. The presence of high-Pb contamination in soil promoted Cd accumulation in shoots of celery. Celery is considered a species with high risks in Cd pollution and low risks in Pb pollution. Among the tested cultivars, cv. Shuanggang- kangbing (SGKB) had the lowest shoot Cd and Pb accumulating abilities, and thus is the most important material for breeding of pollution-safe cultivars (PSCs) to minimize Cd and Pb accumulations in celery.

  13. Raman scattering and electrical studies of the phase stability in the Hg{sub 1-x}Cd{sub x}Te

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anand [Indian Institute of Technology, Department of Physics, Delhi (India); Solid State Physics Laboratory, Delhi (India); Shukla, A.K. [Indian Institute of Technology, Department of Physics, Delhi (India); Pal, R. [Solid State Physics Laboratory, Delhi (India)

    2016-05-15

    Raman scattering is performed to access phase stability in the boron-implanted Hg{sub 0.7}Cd{sub 0.3}Te with fluences ranging from 1 x 10{sup 12} to 1 x 10{sup 15} cm{sup -2}. Threshold fluence for the formation of an amorphous phase is invoked here using Thomas-Fermi statistical model. Asymmetric broadening and red shift of the Raman active HgTe-like LO phonon mode are observed with varying fluencies. Electrical properties such as sheet carrier concentration and mobility are also changed with the fluence and reach their saturated values beyond threshold fluence of 5 x 10{sup 13} cm{sup -2}. Threshold fluence for the formation of amorphous phase is also validated by the Raman measurements and electrical transport properties in the implanted layers. The excess free energy of 6.8 kJ/mole is found corresponding to the threshold fluence for phase transition. (orig.)

  14. Interface Lattice Engineering of Si Composite Wafers for Large-Format HgCdTe Infrared Focal Plane Arrays

    Science.gov (United States)

    2012-08-07

    sessile dislocation. Examples of such sessile dislocation coalescence are the Lomer lock a 2 [011̄] + a 2 [101] → a 2 [110], (2.22) or a Lomer-Cottrell...Hg droplets condensing on to the layer. This will leave concentric circular marks where the Hg drop forms and evaporates away as seen in figure 5.2(d...sake, also assume that bα+ bβ = bsessile, where the result is a sessile dislocation. Finally, stipulate that when is near a side wall, α dislocations

  15. A 4K x 4K HgCdTe astronomical camera enabled by the JWST NIR detector development program

    Science.gov (United States)

    Hall, Donald N. B.; Luppino, Gerard; Hodapp, Klaus W.; Garnett, James D.; Loose, Markus; Zandian, Majid

    2004-09-01

    The ambitious science goals of the James Webb Space Telescope (JWST) have driven spectacular advances in λco ~ 5um detector technology over the past five years. This paper reviews both the UH/RSC team"s Phase A development and evaluation of 2Kx2K arrays exceeding the detector requirements for JWST"s near infrared instruments and also the hardware integration of these into a 4Kx4K (16Mpxl) close packed mosaic focal plane array housed in an Ultra Low Background test facility. Both individual first generation 2Kx2K SCA"s and 4Kx4K mosaic focal planes have been extensively characterized in the laboratory and, since September 2003, a NIR camera utilizing the 4Kx4K mosaic focal plane has been in use for nearly 100 nights at the UH 2.2 m telescope on Mauna Kea. Typical test results for the first generation 2Kx2K arrays and their integration into 4Kx4K mosaic focal planes are reported. Demonstration of the design concepts and both array and mosaic focal plane performance in actual hardware, as described here, has provided the foundation for design iterations leading to later generations of 2Kx2K arrays and 4Kx4K mosaic focal planes. Four major technology developments leading to first generation hardware demonstrations of both 2Kx2K SCA"s and a 4Kx4K mosaic FPA are reviewed. These are: 1) improvement in test equipment and procedures to characterize the detectors against JWST requirements and goals, primarily at 37K but with the capability to test from 30K to 100K; 2) optimization of λc ~ 5 um MBE HgCdTe material on a CZT substrate for low dark current (goal of 0.003 e-/sec at 37K) with high quantum efficiency, low cross-talk and greatly reduced image persistence; 3) development of the 2Kx2K HAWAII-2RG multiplexer designed specifically to take full advantage of these detector characteristics for a wide range of astronomical applications (and fully compatible with an ASIC controller developed under the JWST Instrument Technology Development initiative) and 4) development of

  16. Preparation of a new Cd(II)-imprinted polymer and its application to determination of cadmium(II) via flow-injection-flame atomic absorption spectrometry.

    Science.gov (United States)

    Gawin, Marta; Konefał, Jadwiga; Trzewik, Bartosz; Walas, Stanisław; Tobiasz, Anna; Mrowiec, Halina; Witek, Ewa

    2010-01-15

    A new cadmium(II)-imprinted polymer based on cadmium(II) 2,2'-{ethane-1,2-diylbis[nitrilo(E)methylylidene]} diphenolate-4-vinylpyridine complex was obtained via suspension polymerization. The beads were used as a minicolumn packing for flow-injection-flame atomic absorption spectrometry (FI-FAAS) determination of cadmium(II) in water samples. Sorption effectiveness was optimal within pH range of 6.6-7.7. Nitric acid, 0.5% (v/v) was used as eluent. Fast cadmium(II) sorption by the proposed material enabled to apply sample flow rates up to 10mLmin(-1) without loss in sorption effectiveness. Enrichment factor (EF), concentration efficiency (CE) and limit of detection (LOD, 3sigma) found for 120-s sorption time were 117, 39.1min(-1) and 0.11microgL(-1), respectively. Sorbent stability was proved for at least 100 preconcentration cycles (RSD=2.9%). When compared to non-imprinted polymer the new Cd(II)-imprinted polymer exhibited improved selectivity towards cadmium(II) against other heavy metal ions, especially Cu(II) and Pb(II), as well as light metal ions. Accuracy of the method was tested for ground water and waste water certified reference materials and fortified water. The method was applied to Cd(II) determination in natural water samples.

  17. Transcriptome sequencing and differential gene expression analysis in Viola yedoensis Makino (Fam. Violaceae) responsive to cadmium (Cd) pollution

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jian [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute of Sichuan Agricultural University, Wenjiang, Sichuan (China); Luo, Mao [Drug Discovery Research Center of Luzhou Medical College, Luzhou, Sichuan (China); Zhu, Ye; He, Ying; Wang, Qin [Department of Pharmacy of Luzhou Medical College, Luzhou, Sichuan (China); Zhang, Chun, E-mail: zc83good@126.com [Department of Pharmacy of Luzhou Medical College, Luzhou, Sichuan (China)

    2015-03-27

    Viola yedoensis Makino is an important Chinese traditional medicine plant adapted to cadmium (Cd) pollution regions. Illumina sequencing technology was used to sequence the transcriptome of V. yedoensis Makino. We sequenced Cd-treated (VIYCd) and untreated (VIYCK) samples of V. yedoensis, and obtained 100,410,834 and 83,587,676 high quality reads, respectively. After de novo assembly and quantitative assessment, 109,800 unigenes were finally generated with an average length of 661 bp. We then obtained functional annotations by aligning unigenes with public protein databases including NR, NT, SwissProt, KEGG and COG. In addition, 892 differentially expressed genes (DEGs) were investigated between the two libraries of untreated (VIYCK) and Cd-treated (VIYCd) plants. Moreover, 15 randomly selected DEGs were further validated with qRT-PCR and the results were highly accordant with the Solexa analysis. This study firstly generated a successful global analysis of the V. yedoensis transcriptome and it will provide for further studies on gene expression, genomics, and functional genomics in Violaceae. - Highlights: • A de novo assembly generated 109,800 unigenes and 5,4479 of them were annotated. • 31,285 could be classified into 26 COG categories. • 263 biosynthesis pathways were predicted and classified into five categories. • 892 DEGs were detected and 15 of them were validated by qRT-PCR.

  18. Determination of Cd, Hg, Pb and Tl in coal and coal fly ash slurries using electrothermal vaporization inductively coupled plasma mass spectrometry and isotopic dilution

    Energy Technology Data Exchange (ETDEWEB)

    Maia, S.M.; Pozebon, D.; Curtius, A.J. [Univ. Federal de Santa Catarina, Florianopolis, SC (Brazil)

    2003-07-01

    A method has been investigated for the determination of Cd, Hg, Pb and Tl in coal and in coal fly ash, using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry and isotope dilution. The slurry, 25 mg ml{sup -1}, was prepared by mixing the powdered sample (less than or equal to 36 - 45 mm) with acid solutions (nitric acid for coal and nitric and hydrofluoric acids for coal fly ash) and submitting the mixture to an ultrasonic agitation, letting it stand afterwards in a water bath at 60{sup o}C for 2 h. An ultrasonic probe was used to homogenize the slurry in the autosampler cup just before its introduction into the graphite tube. The best conditions were determined regarding analyte sensitivity, furnace temperature program, amount of modifier, acid concentration, gas flow rate and particle size. For Hg, the pyrolysis stage was omitted and a low vaporization temperature was used (450 - 1000{sup o}C); the residual matrix was eliminated in the first step of the following cycle. The modifiers used were: Pd for Cd and Tl; Au, Ir or Pd for Hg; Ir or Pd for Pb. The accuracy of the method was checked by analyzing six certified coal reference materials (SARM 20, SARM 19, BCR No. 40, BCR No. 180, BCR No. 181 and NIST 1630a) and one certified coal fly ash (NIST 1633b). With one exception (Hg in BCR No. 180), the found concentrations were typically within 95% confidence interval of the certified values, or close enough to the recommended values, as long as the samples were ground to a small enough particle size. The limits of detection were typically around 0.08 {mu}g g{sup -1}, 0.03 {mu}g g{sup -1}, 1 {mu}g g{sup -1} and 0.02 {mu}g g{sup -1} for Cd, Hg, Pb and Tl, respectively. The precision was also adequate with relative standard deviations of usually < 5%.

  19. EFFECTS OF OCEAN ACIDIFICATION ON THE ACUTE TOXICITY OF Cd2+ AND Hg2+ TO JUVENILE MERETRIX LAMARCKII%海洋酸化条件下Cd2+和Hg2+对斧文蛤幼贝急性毒性效应

    Institute of Scientific and Technical Information of China (English)

    蒋国萍; 肖国强; 张炯明; 刘广绪; 滕爽爽; 方军; 柴雪良

    2016-01-01

    为研究在海洋酸化条件下重金属污染物对滩涂贝类的影响,采用半静态急性毒性实验的研究方法,利用海洋酸化人工模拟系统,分析了不同酸化条件下(对照组pH 8.20、酸化组pH分别为7.80、7.60和7.40)Cd2+和Hg2+对斧文蛤(Meretrix lamarckii)幼贝急性毒性效应的影响.实验结果表明:在实验设定的海洋酸化范围内,单一的海洋酸化对斧文蛤幼贝的存活没有显著性影响,但海洋酸化显著增强了Cd2+和Hg2+的急性毒性.与对照组相比,酸化组Cd2+和Hg2+的毒性随着酸化程度的加剧而呈现出逐渐增强的趋势;Cd2+和Hg2+均在pH 7.40时对斧文蛤的毒性最强,其96h半致死(96h LC50)浓度分别为4.068 mg/L(Cd2+)和10.332 mg/L(Hg2+),明显低于pH8.20、7.80和7.60时其对斧文蛤幼贝的96h LC50浓度(其值分别为Cd2+ 6.458、5.947、4.728 mg/L和Hg2+ 12.027、11.169、10.595 mg/L).研究有助于丰富海洋酸化与重金属毒理作用在海洋贝类中的研究内容,为斧文蛤资源恢复和海洋环境保护提供科学依据.

  20. 长波碲镉汞材料 As 掺杂激活研究%Research on arsenic-doping activation in LW HgCdTe

    Institute of Scientific and Technical Information of China (English)

    张舟; 陈慧卿; 朱西安

    2015-01-01

    Arsenic-doped long-wavelength HgCdTe was realized by ion implantation.As doping medium,arsenic shows amphiprotic doping property.When Arsenic only occupies Te-site to be acceptor,P type HgdTe material can be formed.After the arsenic-doped HgCdTe is annealed in the mercury atmosphere,the change of electrical property which is caused by annealing is analyzed.And the effect of mercury pressure,temperature and time on arsenic activa-tion is studied.The activation effect is analyzed by Hall measurement and SIMS.In the end,when the arsenic-doped HgCdTe is annealed in the high temperature and high mercury atmosphere,arsenic activation is achieved.%利用离子注入工艺实现长波碲镉汞材料的 As 掺杂,As 作为掺杂介质表现出两性掺杂行为,而 As 只有占据 Te 位成为受主才能形成 P 型碲镉汞材料。通过对砷掺杂碲镉汞材料在汞气氛中进行退火,分析注入退火引起的样品电学性质的变化,对砷激活退火采用的汞压、温度及时间进行了研究,利用霍尔测试和二次离子质谱仪(SIMS)等手段分析激活效果,研究发现,高温富汞热退火可以实现碲镉汞 As 激活。

  1. Temporal changes in Hg, Pb, Cd and Zn environmental concentrations in the southern Baltic Sea sediments dated with 210Pb method

    Directory of Open Access Journals (Sweden)

    Tamara Zalewska

    2015-01-01

    Full Text Available The article presents data on heavy metal – Hg, Pb, Cd and Zn – distribution in the layers of marine sediments from the off-shore areas of the southern Baltic Sea: Gdańsk Deep, SE Gotland Basin and Bornholm Deep. Depth profiles of metal concentrations were converted to time-based profiles using the 210Pb dating method and verified by 137Cs distribution in the vertical profile. The linear sedimentation rates in the Gdańsk Deep and SE Gotland Basin are similar, 0.18 cm yr−1 and 0.14 cm yr−1, respectively, while the region of the Bornholm Deep is characterized by a greater sedimentation rate: 0.31 cm yr−1. Regarding anthropogenic pressure, Gdańsk Deep receives the largest share among the analyzed regions. The maximal metal concentrations detected in this area were Zn – 230 mg kg−1, Pb – 77 mg kg−1, Cd – 2.04 mg kg−1 and Hg – 0.27 mg kg−1. The least impact of anthropogenic pressure was noticeable in SE Gotland Basin. The combination of sediment dating with the analysis of vertical distribution of heavy metals in sediments benefited in the determination of target metal concentrations used in environmental status assessments. Reference values of heavy metal concentrations in marine sediments were determined as: Zn – 110 mg kg−1, Pb – 30 mg kg−1, Cd – 0.3 mg kg−1 and Hg – 0.05 mg kg−1 from the period of minor anthropogenic pressure. Basing on the determined indices: enrichment factor (EF, geoaccumulation indicator (Igeo and contamination factor (CF the status of marine environment was assessed regarding the pollution with heavy metals.

  2. Syntheses, characterization and electrocatalytical comparison of two cadmium-containing mono-lacunary Wells-Dawson polyoxometalates, α1- and α2-[P2W17Cd(H2OO61]8-

    Directory of Open Access Journals (Sweden)

    Zonoz Farrokhzad Mohammadi

    2014-01-01

    Full Text Available Two new cadmium-containing Wells-Dawson polyoxometalates K8[α1-P2W17Cd(OH2O61]•16H2O (α1-P2W17Cd and K8[α2-P2W17Cd(OH2 O61]•16H2O (α2-P2W17Cd were synthesized as aqueous soluble potassium salts. The cadmium-substituted complexes have been characterized by IR, 31P NMR, 113Cd NMR spectroscopy and cyclic voltametry (CV. Redox activities for the tungsten and cadmium centers have been observed by using cyclic voltammetry. It was found that the presence of cadmium decreases the electrocatalytic activity of the [α1-LiP2W17O61]9- and α2-[P2W17O61]10-heteropolyanions.

  3. Cadmium (II) pyrrolidine dithiocarbamate complex as single source precursor for the preparation of CdS nanocrystals by microwave irradiation and conventional heating process

    Science.gov (United States)

    Marx Nirmal, R.; Pandian, K.; Sivakumar, K.

    2011-01-01

    The complex of cadmium with pyrrolidine dithiocarbamate Cd(pdtc)2 has been used as single source precursor for the synthesis of CdS nanoparticles. The formation of CdS nanostructures was achieved by thermal decomposition of the complex under microwave irradiation and conventional heating in presence of hexadecylamine. The CdS nanoparticles with disordered close-packed structure were obtained under microwave irradiation, whereas wurtzite hexagonal phase CdS nanorods were obtained by conventional heating method (up to 150 °C). Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and high resolution transmission electron microscopy (HRTEM) studies also were carried out to study the structure and morphology of nanoparticles. The optical property of the CdS nanoparticles was studied by UV-visible and fluorescence emission spectral studies. Fluorescence measurements on the CdS nanoparticles show a strong emission spectrum with two sub bands that are attributed to band-edge and surface-defect emissions. The reduction of a suitable cadmium metal complex is considered to be one of the single pot methods to generate CdS semiconductor nanoparticles with different shapes and high yield.

  4. Cadmium (II) pyrrolidine dithiocarbamate complex as single source precursor for the preparation of CdS nanocrystals by microwave irradiation and conventional heating process

    Energy Technology Data Exchange (ETDEWEB)

    Marx Nirmal, R. [Department of Physics, Anna University Chennai, Chennai, Tamil Nadu 600025 (India); Pandian, K. [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600025 (India); Sivakumar, K., E-mail: ksivakumar@annauniv.edu [Department of Physics, Anna University Chennai, Chennai, Tamil Nadu 600025 (India)

    2011-01-15

    The complex of cadmium with pyrrolidine dithiocarbamate Cd(pdtc){sub 2} has been used as single source precursor for the synthesis of CdS nanoparticles. The formation of CdS nanostructures was achieved by thermal decomposition of the complex under microwave irradiation and conventional heating in presence of hexadecylamine. The CdS nanoparticles with disordered close-packed structure were obtained under microwave irradiation, whereas wurtzite hexagonal phase CdS nanorods were obtained by conventional heating method (up to 150 deg. C). Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and high resolution transmission electron microscopy (HRTEM) studies also were carried out to study the structure and morphology of nanoparticles. The optical property of the CdS nanoparticles was studied by UV-visible and fluorescence emission spectral studies. Fluorescence measurements on the CdS nanoparticles show a strong emission spectrum with two sub bands that are attributed to band-edge and surface-defect emissions. The reduction of a suitable cadmium metal complex is considered to be one of the single pot methods to generate CdS semiconductor nanoparticles with different shapes and high yield.

  5. Constrained DFT+U approach for understanding the magnetic behaviour of ACr2O4 (A = Zn, Mg, Cd and Hg) compounds

    Science.gov (United States)

    Lal, Sohan; Pandey, Sudhir K.

    2017-03-01

    In this work, we try to understand the inconsistency reported by Yaresko (2008) [10] in the theoretically estimated sign of nearest neighbour exchange coupling constant (J1) and variation of its magnitude with increasing U in ACr2O4 (A = Zn, Cd, Mg and Hg) compounds by using density functional theory. In unconstrained calculations, the sign of J1 and variation of its magnitude as a function of U in the present study are not consistent with the experimental data and not according to the relation, J1 ∝ t2/U, respectively especially for CdCr2O4 for U > 3 eV and HgCr2O4 for U = 2- 6 eV. Such an inconsistent behaviour of J1 is almost similar to that of Yaresko for these two compounds for U = 2- 4 eV. For ZnCr2O4 and MgCr2O4, the sign of J1 and variation of its magnitude in the present work are in accordance with the experimental data and above mentioned relation, respectively for U = 2- 6 eV and are similar to that of Yaresko for ZnCr2O4 for U = 2- 4 eV. However, in constrained calculations the sign of J1c and variation of its magnitude in the present work are according to experimental data and above mentioned relation, respectively for all four compounds. Hence, the present study shows the importance of constrained calculations in understanding the magnetic behaviour of these spinels. The values of magnitude of Curie-Weiss temperature (ΘCW)c for ZnCr2O4 > MgCr2O4 > CdCr2O4 > HgCr2O4 for U = 2- 5 eV, which are according to the order of experimentally observed values for these spinels. The calculated values of (ΘCW)c for ZnCr2O4, MgCr2O4, CdCr2O4 and HgCr2O4 are -982 K, -721 K, -147 K and -122 K, respectively at U = 5 eV.

  6. [Simultaneous determination of the total content of As, Ba, Cd, Cr, Hg, Pb, Se, Sb in paint coating on toys by ICP-AES].

    Science.gov (United States)

    Liu, Chong-hua; Zhong, Zhi-guang; Li, Bing-zhong; Huang, Li-na; Yi, Le-zhou

    2002-10-01

    ICP-AES was used for the simultaneous determination of the total content of As, Ba, Cd, Cr, Hg, Pb, Se, Sb in paint coating on toys. Digestion procedures of these materials with different acid mixtures have been developed. The sample was dissvolved in the acid mixture of nitric acid, tartaric acid, and a little phosphoric acid. The matrix elements effect was studied and the preferable experimental conditions were investigated. The recovery rates of this procedure were between 99% and 109%. The RSD was within 1.5%. The proposed method was simple, rapid and can be used in daily inspection of toys.

  7. The growth of various buffer layer structures and their influence on the quality of (CdHg)Te epilayers

    CSIR Research Space (South Africa)

    Gouws, GJ

    1993-05-01

    Full Text Available to the formation of electrically active defects in the material. An intermediate ZnTe layer was used to select the (100) orientation and (100) CdTe layers were then deposited on this ZnTe layer. The quality of the resultant CdTe buffer was found to critically...

  8. Subcellular cadmium distribution and antioxidant enzymatic activities in the leaves of two castor (Ricinus communis L.) cultivars exhibit differences in Cd accumulation.

    Science.gov (United States)

    Zhang, Hanzhi; Guo, Qingjun; Yang, Junxing; Shen, Jianxiu; Chen, Tongbin; Zhu, Guangxu; Chen, Hui; Shao, Chunyan

    2015-10-01

    The aims of this study were: (1) the study of cadmium (Cd) accumulation and toxicity in different castor cultivars (Ricinus communis L.); (2) to investigate changes in antioxidant enzymatic activities and the subcellular distribution of Cd in young and old leaves from two different castor cultivars, after exposure to two different Cd concentrations, and explore the underlying mechanism of Cd detoxification focusing on antioxidant enzymes and subcellular compartmentalization. The Cd concentration, toxicity, and subcellular distribution, as well as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were measured in Zibo-3 and Zibo-9 cultivars after exposure to two different concentrations of Cd (2mg/L and 5mg/L) for 10 days. This research revealed Cd accumulation characteristics in castor are root>stem>young leaf>old leaf. Castor tolerance was Cd dose exposure and the cultivars themselves dependent. Investigation of subcellular Cd partitioning showed that Cd accumulated mainly in the heat stable protein (HSP) and cellular debris fractions, followed by the Cd rich granule (MRG), heat denatured protein (HDP), and organelle fractions. With increasing Cd concentration in nutrient solution, the decreased detoxified fractions (BDM) and the increased Cd-sensitive fractions (MSF) in young leaves may indicate the increased Cd toxicity in castor cultivars. The BDM-Cd fractions or MSF-Cd in old leaves may be linked with Cd tolerance of different cultivars of castor. The antioxidant enzymes that govern Cd detoxification were not found to be active in leaves. Taken together, these results indicate Cd tolerance and toxicity in castor can be explained by subcellular partitioning.

  9. Human renal tubular cells contain CD24/CD133 progenitor cell populations: Implications for tubular regeneration after toxicant induced damage using cadmium as a model.

    Science.gov (United States)

    Shrestha, Swojani; Somji, Seema; Sens, Donald A; Slusser-Nore, Andrea; Patel, Divyen H; Savage, Evan; Garrett, Scott H

    2017-09-15

    The proximal tubules of the kidney are target sites of injury by various toxicants. Cadmium (Cd(+2)), an environmental nephrotoxicant can cause adverse effects and overt renal damage. To decipher the mechanisms involved in nephrotoxicity, an in vitro model system is required. Mortal cultures of human proximal tubule (HPT) cells have served, as models but are difficult to acquire and do not lend themselves to stable transfection. The immortalized human proximal tubule cell line HK-2, has served as a model but it lacks vectorial active transport and shows signs of lost epithelial features. Recently a new proximal tubule cell line was developed, the RPTEC/TERT1, and the goal of this study was to determine if this cell line could serve as a model to study nephrotoxicity. Global gene expression analysis of this cell line in comparison to the HK-2 and HPT cells showed that the RPTEC/TERT1 cells had gene expression patterns similar to HPT cells when compared to the HK-2 cells. The HPT and the RPTEC/TERT1 cell line had an increased population of stem/progenitor cells co-expressing CD24 and CD133 when compared to the HK-2 cells. The level of expression of cadherins, claudins and occludin molecules was also similar between the RPTEC/TERT1 and the HPT cells. Acute exposure to Cd(+2) resulted in necrosis of the RPTEC/TERT1 cells when compared to the HK-2 cells which died by apoptosis. Thus, the RPTEC/TERT1 cells are similar to HPT cells and can serve as a good model system to study mechanisms involved in toxicant induced renal damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Evaluation of HgCdTe on GaAs Grown by Molecular Beam Epitaxy for High-Operating-Temperature Infrared Detector Applications

    Science.gov (United States)

    Wenisch, J.; Schirmacher, W.; Wollrab, R.; Eich, D.; Hanna, S.; Breiter, R.; Lutz, H.; Figgemeier, H.

    2015-09-01

    Molecular beam epitaxy (MBE) growth of HgCdTe (MCT) on alternative substrates enables production of both cheaper and more versatile (third-generation) infrared (IR) detectors. After rapid progress in the development of MBE-grown MCT on GaAs in recent years, the question of whether the considerable benefits of this material system are also applicable to high-operating-temperature (HOT) applications demands attention. In this paper, we present a mid-wavelength-IR 640 × 512 pixel, 15- μm-pitch focal-plane array with operability of 99.71% at operating temperature of 120 K and low dark current density. In the second part of the paper, MBE growth of short-wavelength IR material with Cd fraction of up to 0.8 is investigated as the basis for future evaluation of the material for low-light-level imaging HOT applications.

  11. Mercury, cadmium and arsenic contents of calcium dietary supplements.

    Science.gov (United States)

    Kim, Meehye

    2004-08-01

    The cadmium (Cd) and arsenic (As) contents of calcium (Ca) supplements available on the Korean market were determined by a graphite furnace atomic absorption spectrometer using Zeeman background correction and peak area mode after microwave digestion. The mercury (Hg) content of the supplements was measured using an Hg analyser. Recoveries ranged from 92 to 98% for Hg, Cd and As analyses. Fifty-five brands of Ca supplements were classified into seven categories based on the major composite: bone, milk, oyster/clam shell, egg shell, algae, shark cartilage and chelated. The means of Hg, Cd and As in Ca supplements were 0.01, 0.02, and 0.48 mg kg(-1), respectively. Ca supplements made of shark cartilage had the highest means of Hg (0.06 mg kg(-1)) and Cd (0.13 mg kg(-1)). The mean daily intakes of Hg and Cd from the supplement were estimated as about 0.1-0.2 microg, with both contributing less than 0.4% of provisional tolerable daily intakes set by the Food and Agricultural Organization/World Health Organization Joint Food Additive and Contaminants Committee.

  12. Accumulation of mercury and cadmium in rice from paddy soil near a mercury mine.

    Science.gov (United States)

    Li, W C; Ouyang, Y; Ye, Z H

    2014-11-01

    Paddy soil and rice (Oryza sativa L.) in the Wanshan mining area in Guizhou Province, China, have been contaminated by toxic trace metals such as cadmium (Cd) and mercury (Hg). The present study examined correlations between the types and physicochemical parameters of the soil and the contents of trace metals and the different forms of Hg in rice. The health risks of consuming contaminated rice from the Wanshan mining area were also assessed. Sequential extraction procedures were used to investigate the chemical behavior of Hg in the soil. The results showed that Hg and Cd were the most abundant trace metals in the Wanshan mining area. The toxic methylmercury (MeHg) content was substantial in brown rice, and the total amounts of total Hg (THg), diethylenetriaminepentaacetic acid-Hg, and water-soluble Hg varied in the rhizosphere and non-rhizosphere soils. An antagonistic interaction between Mn in brown rice, straw, and husk and MeHg in brown rice was also shown. An analysis of calculated dietary intake, target hazard quotients, and hazard indexes showed a potential risk of transferring Hg, MeHg, and Cd to humans when rice from the Wanshan mining area is consumed. Therefore, it must be concluded that consuming contaminated rice near the Wanshan mining area is a potential threat to human health.

  13. Isolation and control of voids and void-hillocks during molecular beam epitaxial growth of HgCdTe

    Science.gov (United States)

    Chandra, D.; Aqariden, F.; Frazier, J.; Gutzler, S.; Orent, T.; Shih, H. D.

    2000-06-01

    Formation of small voids and defect complexes involving small voids during the molecular beam epitaxial growth of mercury cadmium telluride on cadmium zinc telluride was investigated. Some of these defects were demonstrated to form away from the substrate-epi interface. Other defects were demonstrated to close before reaching the top surface without leaving any perturbations on the surface, thus remaining completely hidden. The voids, which formed away from the substrate-epifilm fixed interface, nucleated on defects introduced into the film already grown, leading to the formation of defect complexes, unlike the voids which nucleated at the substrate-epifilm fixed interface. These defect complexes are decorated with high density dislocation nests. The voids which closed before reaching the film surface usually also nucleated slightly away from the film-substrate interface, continued to replicate for a while as the growth progressed, but then relatively rapidly closed off at a significant depth from the film surface. These voids also appeared to form defect complexes with other kinds of defects. Correlations between these materials defects and performance of individual vertically integrated photodiode (VIP) devices were demonstrated, where the relative location of these defects with respect to the junction boundary appears to be particularly important. Elimination or reduction of fluctuations in relative flux magnitudes or substrate temperature, more likely during multi-composition layer growth, yielded films with significantly lower defect concentrations.

  14. Le Tellurure de Cadmium amorphe oxygéné a - CdTe:O Synthèse et étude de quelques propriétés physico-chimiques

    OpenAIRE

    El Azhari, Youssef

    2003-01-01

    The work presented in this thesis is part of the study of the properties of thin layers of semiconductor materials based on cadmium telluride CdTe. The study of the influence of various deposition parameters on the properties of CdTe thin films has enabled us to develop a method of preparing a new material based on CdTe. It is the oxygenated amorphous cadmium telluride aCddTe: O. The thin film deposition of CdTe a-O from a target polycrystalline CdTe requires the use of a plasma high oxidizin...

  15. RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

    Institute of Scientific and Technical Information of China (English)

    J.X.Zhu; B.Yu; J.H.Li; Y.F.Nie

    2001-01-01

    Several typical methods for the recovery of Ni-Cd batteries are described in detail.Based on the comparing of hydrometallurgical and pyrometallurgical processes,the latter was selected as the suitable method for recycling Ni-Cd batteries in China.

  16. Comparison on cellular mechanisms of iron and cadmium accumulation in rice: prospects for cultivating Fe-rich but Cd-free rice.

    Science.gov (United States)

    Gao, Lei; Chang, Jiadong; Chen, Ruijie; Li, Hubo; Lu, Hongfei; Tao, Longxing; Xiong, Jie

    2016-12-01

    Iron (Fe) is essential for rice growth and humans consuming as their staple food but is often deficient because of insoluble Fe(III) in soil for rice growth and limited assimilation for human bodies, while cadmium (Cd) is non-essential and toxic for rice growth and humans if accumulating at high levels. Over-accumulated Cd can cause damage to human bodies. Selecting and breeding Fe-rich but Cd-free rice cultivars are ambitious, challenging and meaningful tasks for researchers. Although evidences show that the mechanisms of Fe/Cd uptake and accumulation in rice are common to some extent as a result of similar entry routes within rice, an increasing number of researchers have discovered distinct mechanisms between Fe/Cd uptake and accumulation in rice. This comprehensive review systematically elaborates and compares cellular mechanisms of Fe/Cd uptake and accumulation in rice, respectively. Mechanisms for maintaining Fe homeostasis and Cd detoxicification are also elucidated. Then, effects of different fertilizer management on Fe/Cd accumulation in rice are discussed. Finally, this review enumerates various approaches for reducing grain Cd accumulation and enhancing Fe content in rice. In summary, understanding of discrepant cellular mechanisms of Fe/Cd accumulation in rice provides guidance for cultivating Fe-fortified rice and has paved the way to develop rice that are tolerant to Cd stress, aiming at breeding Fe-rich but Cd-free rice.

  17. Toxicity of cadmium sulfide (CdS) nanoparticles against Escherichia coli and HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Sk Tofajjen; Mukherjee, Samir Kumar, E-mail: dr.samirmukherjee@gmail.com

    2013-09-15

    Highlights: • Toxic effect of CdS NPs on the growth and cell division in E. coli was studied. • CdS NPs affected cell surface topology and cell division. • Downregulation of both FtsZ and FtsQ was observed due to NPs exposure. • CdS NPs affected HeLa cell morphology with fragmented nuclei. • All such effects might be due to elevated oxidative stress. -- Abstract: The present study endeavours to assess the toxic effect of synthesized CdS nanoparticles (NPs) on Escherichia coli and HeLa cells. The CdS NPs were characterized by DLS, XRD, TEM and AFM studies and the average size of NPs was revealed as ∼3 nm. On CdS NPs exposure bacterial cells changed morphological features to filamentous form and damage of the cell surface was found by AFM study. The expression of two conserved cell division components namely ftsZ and ftsQ in E. coli was decreased both at transcriptional and translational levels upon CdS NPs exposure. CdS NPs inhibited proper cell septum formation without affecting the nucleoid segregation. Viability of HeLa cells declined with increasing concentration of CdS NPs and the IC{sub 50} value was found to be 4 μg/mL. NPs treated HeLa cells showed changed morphology with condensed and fragmented nuclei. Increased level of reactive oxygen species (ROS) was found both in E. coli and HeLa cells on CdS NPs exposure. The inverse correlation between declined cell viabilities and elevated ROS level suggested that oxidative stress seems to be the key event by which NPs induce toxicity both in E. coli and HeLa cells.

  18. Synthesis of hydroximic acid functionalized PMMA/AM/HOA resin and its adsorbability for Hg2+ and Cd2+%羟肟酸功能化PMMA/AM/HOA的合成及对Hg2+和Cd2+的吸附性能

    Institute of Scientific and Technical Information of China (English)

    孙林; 刘春萍; 马松梅; 孙豪展; 陈秋

    2016-01-01

    用悬浮聚合法合成了甲基丙烯酸甲酯(MMA)与丙烯酰胺(AM)的共聚物PMMA/AM,再经羟胺改性制备了含羟肟酸功能基的改性PMMA/AM/HOA树脂.通过红外光谱(FTIR)和热重分析(TG)对PMMA/AM/HOA树脂的结构和稳定性进行了表征.以PMMA/AM/HOA为吸附剂,考察了温度、吸附时间、pH值和金属离子浓度等条件对Hg2+、Cd2+两种金属离子吸附性能的影响.结果表明,改性树脂对Hg2+、Cd2+具有良好的吸附能力,其实验吸附量分别为0.822和0.384 mmol·g-1.改性树脂对Hg2+和Cd2+的吸附过程符合拟二级动力学方程,25℃时其二级动力学吸附速率常数分别为5.301×10-2和3.582×10-2g·(mmol·min)-1;改性树脂对Hg2+和Cd2+的吸附量随温度的升高有所增大,吸附过程符合Langmuir和Freundlich吸附等温式.

  19. Purification of cadmium up to 5N+ by vacuum distillation

    Indian Academy of Sciences (India)

    S T Ali; J V Rao; K S Varma; T L Prakash

    2002-11-01

    Cadmium was refined by vacuum distillation, a technique suitable for low boiling and melting point materials, to remove the heavy and low vapour pressure impurities at ppm level. The detailed analysis of the purified Cd as well as raw Cd was done by ICP–OES techniques for 27 impurity elements. Purification was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 3N+ purity indigenous cadmium to 5N+ (99.999%). Analysis confirmed the reduction of total impurity content from 134 ppm (3N7) for raw Cd to 3 ppm (5N7) upon vacuum distilled Cd. The present study shows that the analysis of impurities such as Fe, Mg and Ca are contributed from environmental effect, whereas impurities such as Pb, Bi, Ag, Ni, Cu, Zn and Tl require adaptation of elemental analysing technique to counter dilution effect. The Hg trace analysis can however be carried out by hydride generation techniques.

  20. Geochemical Transformation of Cadmium (Cd) from Creek to Paddy Fields in W Thailand

    Science.gov (United States)

    Kosolsaksakul, Peerapat; Graham, Margaret; Farmer, John

    2013-04-01

    Extensive Cd contamination of paddy soils in Tak Province, western Thailand, a consequence of Zn mining activities, was first established in 2005 and medical studies showed that the health of local communities was being impaired. Mae Tao, Tak Province, comprising many paddy fields and irrigation canals, has been selected for this study of the geochemical transformation of Cd from the contamination source in the mountainous region to the east of the study site through the community irrigation system to the paddy soils. The aim of this research is to (i) investigate the geochemical transformation of Cd as it is transported from the main irrigation creek through the canals and to the paddy fields, (ii) assess the availability of Cd to rice plants, which may be affected by both chemical and physical factors, and (iii) trial some practical treatments to minimise Cd concentrations in rice grains. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Soil Cd concentrations were in the range 2.5-87.6 µg g-1, with higher values being obtained for fields furthest from the main creek. Although current irrigation water Cd inputs are low (mean 1.9 μg L-1; flood period), high loads of suspended particles still contribute additional Cd (4.2-9.8 µg L-1) to the paddy fields. For bioavailability assessment by a 3-step BCR sequential extraction, 70-90% Cd was in the exchangeable; HOAc-extractable fraction. That indicated that most of

  1. AVALIAÇÃO DOS TEORES DE Pb, Cd, Sn, Co, Hg, Mo E As EM SOLOS DA PENÍNSULA FILDES - ANTÁRTICA

    Directory of Open Access Journals (Sweden)

    Bruna M. Dalfior

    Full Text Available Antarctic Continent is one of the few places that has not been explored at all, but studies show that this place is suffering interference by human activities. Therefore, monitoring of this region becomes very important. After optimization and verification of the methodology, the concentrations of Pb, Cd, Sn, Co, Hg, Mo and As in soil samples collected in the Fildes Peninsula, King George Island, Antarctica, were determined by ICP-MS. The ranges found (µg kg-1 were: for Pb 525.2-2314.1, for Cd 54.8-193.8, for Sn 54.8-193.8, for Co 2095.0-11094.1, for Hg < 2.4-54.6, for Mo 5.3-38.7 and for As 120.3-1297.1. In general, the presence of these elements can be attributed to different factors, such as natural composition of soil, melting process and transport of chemical elements caused by physical phenomena as sea and air currents, besides anthropic contamination. Using enrichment factor was possible suggest contribution by anthropic activities mainly for Co and As. Thus, it is important monitoring the elements levels constantly assisting in environmental protection.

  2. Magnetocaloric effect and inhomogeneity of CdCr{sub 2}Se{sub 4} and HgCr{sub 2}Se{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bebenin, N.G., E-mail: bebenin@imp.uran.ru; Zainullina, R.I.; Sukhorukov, Yu P.

    2015-08-01

    Magnetocaloric effect in single crystals of spinels CdCr{sub 2}Se{sub 4} and HgCr{sub 2}Se{sub 4} is studied. The maximum value of the magnetic-field-induced change in entropy in the field of 15 kOe is about 1.4–1.5 J/(kg K). At Curie temperature the entropy change obeys the relation: −ΔS=αH^(2/3)–β. The magnetic transitions in the spinels are found to be noticeably smeared. The experimental data have been compared with the theoretical results obtained for Heisenberg model in the mean field approximation (MFA). It is found that MFA overestimates the change of entropy in a magnetic field and underestimates the influence of inhomogeneity on ΔS. - Highlights: • The maximum value of the magnetic-field-induced change in entropy in CdCr{sub 2}Se{sub 4} and HgCr{sub 2}Se{sub 4} in the field of 15 kOe is found to be about 1.4–1.5 J/(kg K). • At Curie temperature the entropy change obeys the relation: −ΔS= αH^(2/3)−β. • Heisenberg model in the mean field approximation overestimates the change of entropy in magnetic field.

  3. Simultaneous spectrophotometric determination of Cu2+, Hg2+, and Cd2+ ions using 2-(3-hydroxy-1-methylbut-2-enylideneamino)pyridine-3-ol.

    Science.gov (United States)

    Tarighat, Maryam Abbasi; Mohammadi, Khosro

    2015-04-01

    New complexes of Cu2+, Hg2+, and Cd2+ with a recently synthesized Schiff base derived from 2-(3-hydroxy-1-methylbut-2-enylideneamino)pyridine-3-ol were applied for their simultaneous determination with artificial neural networks. A new analytical method using principal component-feed forward neural networks (PC-FFNNs) and principal component-radial basis function networks (PC-RBFNs) was used. Spectral data was reduced using principal component analysis and subjected to ANNs. The data obtained from synthetic mixtures of metal ions were processed by PC-FFNNs and PC-RBFNs. Performances of the proposed methods were tested with regard to relative standard error of prediction. Limit of detections and limit of quantifications were determined. The results obtained by PC-FFNNs and PC-RBFNs were compared to each other. Under the working conditions, the proposed methods were successfully applied to simultaneous determination of Hg2+, Cu2+, and Cd2+ in different water and soil samples. Concentrations of metal ions in the samples were also determined by flame atomic absorption spectrometry (FAAS) and standard addition method. The amounts of metal ions obtained by the proposed methods were in good agreement with those obtained by FAAS and standard addition method.

  4. Survey of trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) in retail samples of flavoured and bottled waters.

    Science.gov (United States)

    Barroso, M F; Ramos, S; Oliva-Teles, M T; Delerue-Matos, C; Sales, M G F; Oliveira, M B P P

    2009-01-01

    Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p difference in Mn, Co, Se and Si content.

  5. Electronic Band Structure and New Magneto-transport Properties in p-type Semiconductor Medium-infrared HgTe / CdTe Superlattice

    Science.gov (United States)

    Nafidi, Ab.; EL Abidi, A.; El Kaaouachi, A.; Nafidi, Ah.

    2005-06-01

    We report here the band structure and new magneto-transport results for HgTe (56 Å) / CdTe (30 Å) superlattice grown by molecular beam epitaxy (MBE). The angular dependence of the transverse magnetoresistance follows the two-dimensional (2D) behaviour. At low temperature, the sample exhibits p type conductivity with a concentration of 1.84×1012 cm-2 and a Hall mobility of 8200 cm2/Vs. The observed Shubnikov-de Haas effect gives a carrier density of 1.80×1012 cm-2. The superlattice heavy holes dominate the conduction in plane with an effective mass of 0.297 m0 and Fermi energy (2D) of 14 meV. In intrinsic regime, the measured gap Eg = 190 meV agree well with calculated Eg(Γ, 300 K) =178 meV. The formalism used here predicts that the system is semiconductor, for our HgTe to CdTe thickness ratio d1/d2 = 1,87, when d2 < 140 Å. In our case, d2=30 Å and Eg (Γ, 4.2 K) = 111 meV. In spite of it, the sample exhibits the features typical of a p type semiconductor and is a medium-infrared detector (7 μm< λ< 11 μm).

  6. Properties of RF sputtered cadmium telluride (CdTe) thin films: Influence of deposition pressure

    Science.gov (United States)

    Kulkarni, R. R.; Pawbake, A. S.; Waykar, R. G.; Rondiya, S. R.; Jadhavar, A. A.; Pandharkar, S. M.; Karpe, S. D.; Diwate, K. D.; Jadkar, S. R.

    2016-04-01

    Influence of deposition pressure on structural, morphology, electrical and optical properties of CdTe thin films deposited at low substrate temperature (100°C) by RF magnetron sputtering was investigated. The formation of CdTe was confirmed by low angle XRD and Raman spectroscopy. The low angle XRD analysis revealed that the CdTe films have zinc blende (cubic) structure with crystallites having preferred orientation in (111) direction. Raman spectra show the longitudinal optical (LO) phonon mode peak ˜ 165.4 cm-1 suggesting high quality CdTe film were obtained over the entire range of deposition pressure studied. Scanning electron microscopy analysis showed that films are smooth, homogenous, and crack-free with no evidence of voids. The EDAX data revealed that CdTe films deposited at low deposition pressure are high-quality stoichiometric. However, for all deposition pressures, films are rich in Cd relative to Te. The UV-Visible spectroscopy analysis show the blue shift in absorption edge with increasing the deposition pressure while the band gap show decreasing trend. The highest electrical conductivity was obtained for the film deposited at deposition pressure 1 Pa which indicates that the optimized deposition pressure for our sputtering unit is 1 Pa. Based on the experimental results, these CdTe films can be useful for the application in the flexible solar cells and other opto-electronic devices.

  7. Toxicity of cadmium sulfide (CdS) nanoparticles against Escherichia coli and HeLa cells.

    Science.gov (United States)

    Hossain, Sk Tofajjen; Mukherjee, Samir Kumar

    2013-09-15

    The present study endeavours to assess the toxic effect of synthesized CdS nanoparticles (NPs) on Escherichia coli and HeLa cells. The CdS NPs were characterized by DLS, XRD, TEM and AFM studies and the average size of NPs was revealed as ∼3 nm. On CdS NPs exposure bacterial cells changed morphological features to filamentous form and damage of the cell surface was found by AFM study. The expression of two conserved cell division components namely ftsZ and ftsQ in E. coli was decreased both at transcriptional and translational levels upon CdS NPs exposure. CdS NPs inhibited proper cell septum formation without affecting the nucleoid segregation. Viability of HeLa cells declined with increasing concentration of CdS NPs and the IC₅₀ value was found to be 4 μg/mL. NPs treated HeLa cells showed changed morphology with condensed and fragmented nuclei. Increased level of reactive oxygen species (ROS) was found both in E. coli and HeLa cells on CdS NPs exposure. The inverse correlation between declined cell viabilities and elevated ROS level suggested that oxidative stress seems to be the key event by which NPs induce toxicity both in E. coli and HeLa cells.

  8. Transcriptional regulation of metal transport genes and mineral nutrition during acclimatization to cadmium and zinc in the Cd/Zn hyperaccumulator, Thlaspi caerulescens (Ganges population).

    Science.gov (United States)

    Küpper, Hendrik; Kochian, Leon V

    2010-01-01

    We investigated changes in mineral nutrient uptake and cellular expression levels for metal transporter genes in the cadmium (Cd)/zinc (Zn) hyperaccumulator, Thlaspi caerulescens during whole plant and leaf ontogenesis under different long-term treatments with Zn and Cd. Quantitative mRNA in situ hybridization (QISH) revealed that transporter gene expression changes not only dependent on metal nutrition/toxicity, but even more so during plant and leaf development. The main mRNA abundances found were: ZNT1, mature leaves of young plants; ZNT5, young leaves of young plants; MTP1 (= ZTP1 = ZAT), young leaves of both young and mature plants. Surprisingly different cellular expression patterns were found for ZNT1 and ZNT5, both belonging to the ZIP family of transition metal transporters: ZNT1, photosynthetic mesophyll and bundle sheath cells; ZNT5, nonphotosynthetic epidermal metal storage cells and bundle sheath cells. Thus, ZNT1 may function in micronutrient nutrition while ZNT5 may be involved in metal storage associated with hyperaccumulation. Cadmium inhibited the uptake of Zn, iron (Fe) and manganese (Mn), probably by competing for transporters or by interfering with the regulation of transporter gene expression. Cadmium-induced changes in cellular expression for ZNT1, ZNT5 and MTP1 could also be part of plant acclimatization to Cd toxicity. Defence against Cd toxicity involved enhanced uptake of magnesium (Mg), calcium (Ca) and sulphur (S).

  9. Concentración de Hg, Pb, Cd, Cr y As en hígado de Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae capturado en Veracruz, México

    Directory of Open Access Journals (Sweden)

    Fernando Mendoza-Díaz

    2013-06-01

    Full Text Available La contaminación de los ecosistemas marinos y costeros por metales pesados en el Golfo de México es uno de los problemas que afectan a los recursos naturales del medio acuático. Los tiburones por situarse en niveles tróficos superiores de la red alimenticia acumulan y magnifican cantidades considerables de contaminantes. Por esta razón, el objetivo de este trabajo fue determinar la concentración de cuatro metales pesados (Hg, Cd, Pb y Cr y un metaloide (As en el tiburón punta negra (Carcharhinus limbatus por medio de espectrofotometría de absorción atómica con flama y generador de hidruros. Se muestrearon 19 hígados de tiburones capturados cerca de Tamiahua, Veracruz entre noviembre 2007 y marzo 2008, de los cuales 12 fueron machos adultos, una hembra adulta, tres machos jóvenes y tres hembras jóvenes. Las concentraciones máximas registradas para cada metal fueron: Hg=0.69mg/ kg, Cd=0.43mg/kg, As=27.37mg/kg, Cr=0.35mg/kg. El Pb no fue detectado, no al menos la cantidad mínima de detección requerida por el espectrofotómetro de absorción atómica (0.1mg/kg. Ninguna de las muestras analizadas rebasó los límites máximos permisibles por las leyes mexicanas y americanas.Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae captured in Veracruz, Mexico. Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was

  10. Characterization of a degraded cadmium yellow (CdS) pigment in an oil painting by means of synchrotron radiation based X-ray techniques.

    Science.gov (United States)

    Van der Snickt, Geert; Dik, Joris; Cotte, Marine; Janssens, Koen; Jaroszewicz, Jakub; De Nolf, Wout; Groenewegen, Jasper; Van der Loeff, Luuk

    2009-04-01

    On several paintings of James Ensor (1860-1949), a gradual fading of originally bright yellow areas, painted with the pigment cadmium yellow (CdS), is observed. Additionally, in some areas exposed to light, the formation of small white-colored globules on top of the original paint surface is observed. In this paper the chemical transformation leading to the color change and to the formation of the globules is elucidated. Microscopic X-ray absorption near-edge spectroscopy (mu-XANES) experiments show that sulfur, originally present in sulfidic form (S(2-)), is oxidized during the transformation to the sulfate form (S(6+)). Upon formation (at or immediately below the surface), the highly soluble cadmium sulfate is assumed to be transported to the surface in solution and reprecipitates there, forming the whitish globules. The presence of cadmium sulfate (CdSO(4).2H(2)O) and ammonium cadmium sulfate [(NH(4))(2)Cd(SO(4))(2)] at the surface is confirmed by microscopic X-ray diffraction measurements, where the latter salt is suspected to result from a secondary reaction of cadmium sulfate with ammonia. Measurements performed on cross sections reveal that the oxidation front has penetrated into the yellow paint down to ca. 1-2 microm. The morphology and elemental distribution of the paint and degradation product were examined by means of scanning electron microscopy equipped with an energy-dispersive spectrometer (SEM-EDS) and synchrotron radiation based micro-X-ray fluorescence spectrometry (SR micro-XRF). In addition, ultraviolet-induced visible fluorescence photography (UIVFP) revealed itself to be a straightforward technique for documenting the occurrence of this specific kind of degradation on a macroscale by painting conservators.

  11. Effect of a boron implantation on the electrical properties of epitaxial HgCdTe with different material composition

    Science.gov (United States)

    Lyapunov, D. V.; Pishchagin, A. A.; Grigoryev, D. V.; Korotaev, A. G.; Voitsekhovskii, A. V.; Kokhanenko, A. P.; Iznin, I. I.; Savytskyy, H. V.; Bonchik, A. U.; Dvoretskii, S. A.; Mikhailov, N. N.

    2016-08-01

    In this work the experimental results of investigations of the dynamics of accumulation and spatial distribution of electrically active radiation defects when irradiating epitaxial films of Hg1-xCdxTe (MCT) with different material composition (x). The films, grown by molecular beam epitaxy (MBE) were irradiated by B ions at room temperature in the radiation dose range 1012 -1015 ions/cm2 and with ion energy 100 keV. The results give the differences in implantation profiles, damage accumulation and electrical properties as a function of the material composition of the films.

  12. Evolution of different morphologies of CdS nanoparticles by thermal decomposition of bis(thiourea)cadmium chloride in various solvents

    Energy Technology Data Exchange (ETDEWEB)

    Gaur, Rama; Jeevanandam, P., E-mail: jeevafcy@iitr.ernet.in, E-mail: jeevafcy@iitr.ac.in [Indian Institute of Technology Roorkee, Department of Chemistry (India)

    2015-03-15

    CdS nanoparticles with different morphologies have been synthesized by thermal decomposition of bis(thiourea)cadmium chloride in different solvents without the use of any ligand/surfactant. CdS nanoparticles with pyramid, sponge-like and hexagonal disc-like morphologies were obtained in diphenyl ether (DPE), 1-octadecene (ODE) and ethylene glycol (EG), respectively. In addition, CdS nanoparticles with unique morphologies were obtained when the decomposition of the complex was carried out in mixed solvents (DPE–EG and ODE–EG). Extensive characterization of the CdS nanoparticles was carried out using powder X-ray diffraction, FT-IR spectroscopy, thermal analysis, field-emission scanning electron microscopy, diffuse reflectance spectroscopy and photoluminescence spectroscopy, and detailed mechanism of the formation of CdS nanoparticles with different morphologies in various solvents has been proposed.

  13. Concentration of metallothionein in the liver of chicken which were given cadmium (Cd into their feed

    Directory of Open Access Journals (Sweden)

    Darmono

    2000-12-01

    Full Text Available Metallothionein is a metal-binding protein which always detected in the liver of chicken, especially essential element binding protein such as Zn-thionein. Zinc binding protein is usually used for enzyme activity in normal physiology of the animal. The aim of this study was to detect the effect of Cd given into feed on Zn-thionein contain in the liver of broiler chicken. Forty-five broiler chicken were divided into three groups, which was 15 animals in each group. Group 1 as a control group, Group 2 was given 100 mgCd/kg of feed, and group 3 was given 200 mgCd/kg of feed respectively. Body weight of five chicken per group were measured every day and liver samples of five animals per group were collected at day 7 , 14 and 21 after treatment respectively for analysis of Cd and Zn total concentrations and Cd and Zn binding protein. The result indicated that body weight of chicken in the treatment groups were lower than the control group. Zinc binding protein was highest in the control group after 21 days of treatment (2.35 ug/g, but it was low in the two treatment groups were 1.30 and 0.64 ug/g respectively, in which Cd-thionein was formed. On the other hand total Zn concentration were almost similar between treatment, 20.95 ug/g for the control group and 21.24 ug/g for group 2, and 25.37 ug/g for group 3 respectively (P>0.05. It can be concluded that Cd contamination in feed can cause decreased of Zn-thionein within 21 days of treatment, causing retardation of the animals.

  14. 重金属Cu2+、Cd2+、Hg2+对斑马鱼胚胎发育的毒性效应%Toxic effect of heavy metal ions of Cu2+, Cd2+ and Hg2+ on embryo development of zebrafish (Danio rerio)

    Institute of Scientific and Technical Information of China (English)

    陈玉翠; 陈锦云

    2016-01-01

    在半静态水的条件下,研究了铜离子(Cu2+)、镉离子(Cd2+)和汞离子(Hg2+)对斑马鱼(Danio rerio)胚胎发育的单一和联合毒性效应.采用48 h、72 h、96 h致死率和72 h、96 h孵化抑制率作为生理毒性终点,以其半数致死浓度(LC50)值作为毒性评价标准.结果表明:Cu2+、Cd2+和Hg2+对斑马鱼胚胎的48 h-LC50分别为0.58 mg·L-1、0.72 mg·L-1和0.00046 mg·L-1,72 h-LC50分别为0.39 mg·L-1、1.15 mg·L-1和0.00030 mg·L-1,96 h-LC50分别为0.08 mg·L-1、0.19 mg·L-1和0.00018 mg·L-1;Cu2+、Cd2+和Hg2+的72 h孵化抑制率的LC50分别为0.05 mg·L-1、0.01 mg·L-1和0.00004 mg·L-1,96 h孵化抑制率的LC50分别为0.06 mg·L-1、0.05 mg·L-1和0.00011 mg·L-1;Cu2+、Cd2+和Hg2+对斑马鱼胚胎毒性大小顺序为Hg2+>Cu2+>Cd2+.Cu2+、Cd2+和Hg2+对斑马鱼胚胎的致死率和孵化抑制率均具有明显的剂量-效应关系,72 h孵化抑制率可以作为斑马鱼胚胎最敏感的毒性终点指标.分别用单一毒性Cu2+、Cd2+和Hg2+的96 h-LC50值,按毒性单位1∶1两两混合,对斑马鱼胚胎在第48、第72、第96小时的联合毒性均为协同作用;按毒性单位1∶1∶1混合共存时,对斑马鱼胚胎在第48、第72、第96小时的联合毒性均为拮抗作用.

  15. Visible response of λc=2.5´m HgCdTe HDVIP detectors

    Science.gov (United States)

    Stapelbroek, Maryn G.; Guptill, Matthew; D'Souza, Arvind I.; Bryan, Elizabeth R.; Beck, J. D.; Kinch, M. A.; Robinson, James E.

    2004-08-01

    Cu-doped HDVIP detectors with different cut-off wavelengths are routinely manufactured. The DRS HDVIP detector technology is a front-side-illuminated detector technology. There is no substrate to absorb the visible photons as in backside-illuminated detectors and these detectors should be well suited to respond to visible light. However, HDVIP detectors are passivated using CdTe that absorbs the visible light photons. CdTe strongly absorbs photons of wavelength shorter than about 800 nm. Detectors with varying thickness of CdTe passivation layers were fabricated to investigate the visible response of the 2.5-μm-cutoff detectors. A model was developed to predict the quantum efficiency of the detectors in the near infrared and visible wavelength regions as a function of CdTe thickness. Individual photodiodes (λc = 2.5 μm) in test bars were examined. Measurements of the quantum efficiency as a function of wavelength region will be presented and compared to the model predictions.

  16. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  17. Flowing Liquid Anode Atmospheric Pressure Glow Discharge as an Excitation Source for Optical Emission Spectrometry with the Improved Detectability of Ag, Cd, Hg, Pb, Tl, and Zn.

    Science.gov (United States)

    Greda, Krzysztof; Swiderski, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-09-06

    A novel atmospheric pressure glow discharge generated in contact with a flowing liquid anode (FLA-APGD) was developed as the efficient excitation source for the optical emission spectrometry (OES) detection. Differences in the appearance and the electrical characteristic of the FLA-APGD and a conventional system operated with a flowing liquid cathode (FLC-APGD) were studied in detail and discussed. Under the optimal operating conditions for the FLA-APGD, the emission from the analytes (Ag, Cd, Hg, Pb, Tl, and Zn) was from 20 to 120 times higher as compared to the FLC-APGD. Limits of detections (LODs) established with a novel FLA-APGD system were on average 20 times better than those obtained for the FLC-APGD. A further improvement of the LODs was achieved by reducing the background shift interferences and, as a result, the LODs for Ag, Cd, Hg, Pb, Tl, and Zn were 0.004, 0.040, 0.70, 1.7, 0.035, and 0.45 μg L(-1), respectively. The precision of the FLA-APGD-OES method was evaluated to be within 2-5% (as the relative standard deviation of the repeated measurements). The method found its application in the determination of the content of Ag, Cd, Hg, Pb, Tl, and Zn in a certified reference material (CRM) of Lobster hepatopancreas (TORT-2), four brass samples as well as mineral water and tea leaves samples spiked with the analytes. In the case of brass samples, a reference method, i.e., inductively coupled plasma optical emission spectrometry (ICP-OES) was used. A good agreement between the results obtained with FLA-APGD-OES and the certified values for the CRM TORT-2 as well as the reference values obtained with ICP-OES for the brass samples was revealed, indicating the good accuracy of the proposed method. The recoveries obtained for the spiked samples of mineral water and tea leaves were within the range of 97.5-102%.

  18. Isotherm studies for the determination of Cd (II) ions removal capacity in living biomass of a microalga with high tolerance to cadmium toxicity.

    Science.gov (United States)

    Torres, Enrique; Mera, Roi; Herrero, Concepción; Abalde, Julio

    2014-11-01

    The biosorption characteristics of Cd (II) ions using the living biomass of the marine diatom Phaeodactylum tricornutum were investigated. This microalga is a highly tolerant species to cadmium toxicity; for this reason, it is interesting to know its potential for use in the removal of this metal. The use of living biomass offers better possibilities than that of dead biomass since cadmium can also be bioaccumulated inside the cells. For this purpose, tolerant species are necessary. P. tricornutum is within this category with an EC50,96h of 19.1 ± 3.5 mg Cd (II)/L, and in the present manuscript, it is demonstrated that this microalga has a very good potential for bioremediation of Cd (II) ions in saline habitats. Cadmium removed by the cells was divided into three fractions: total, intracellular and bioadsorbed. The experiments were conducted for 96 h in natural seawater with a concentration range of 1-100 mg Cd (II)/L. Each fraction was characterized every 24 h by sorption isotherms. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin equations. The biosorption was well described by Langmuir isotherm followed by Freundlich. The worst model was Temkin. The biosorption capacity of this microalga for Cd (II) ions was found to be 67.1 ± 3.2 mg/g after 96 h with approximately 40 % of this capacity in the intracellular fraction. The bioconcentration factor determined was 2,204.7 after 96 h and with an initial Cd (II) concentration of 1 mg/L.

  19. Transcriptional up-regulation of genes involved in photosynthesis of the Zn/Cd hyperaccumulator Sedum alfredii in response to zinc and cadmium.

    Science.gov (United States)

    Tang, Lu; Yao, Aijun; Ming Yuan; Tang, Yetao; Liu, Jian; Liu, Xi; Qiu, Rongliang

    2016-12-01

    Zinc (Zn) and cadmium (Cd) are two closely related chemical elements with very different biological roles in photosynthesis. Zinc plays unique biochemical functions in photosynthesis. Previous studies suggested that in some Zn/Cd hyperaccumulators, many steps in photosynthesis may be Cd tolerant or even Cd stimulated. Using RNA-seq data, we found not only that Cd and Zn both up-regulated the CA1 gene, which encodes a β class carbonic anhydrase (CA) in chloroplasts, but that a large number of other Zn up-regulated genes in the photosynthetic pathway were also significantly up-regulated by Cd in leaves of the Zn/Cd hyperaccumulator Sedum alfredii. These genes also include chloroplast genes involved in transcription and translation (rps18 and rps14), electron transport and ATP synthesis (atpF and ccsA), Photosystem II (PSBI, PSBM, PSBK, PSBZ/YCF9, PSBO-1, PSBQ, LHCB1.1, LHCB1.4, LHCB2.1, LHCB4.3 and LHCB6) and Photosystem I (PSAE-1, PSAF, PSAH2, LHCA1 and LHCA4). Cadmium and Zn also up-regulated the VAR1 gene, which encodes the ATP-dependent zinc metalloprotease FTSH 5 (a member of the FtsH family), and the DAG gene, which influences chloroplast differentiation and plastid development, and the CP29 gene, which supports RNA processing in chloroplasts and has a potential role in signal-dependent co-regulation of chloroplast genes. Further morphological parameters (dry biomass, cross-sectional thickness, chloroplast size, chlorophyll content) and chlorophyll fluorescence parameters confirmed that leaf photosynthesis of S. alfredii responded to Cd much as it did to Zn, which will contribute to our understanding of the positive effects of Zn and Cd on growth of this plant.

  20. Effects of rice straw on the speciation of cadmium (Cd) and copper (Cu) in soils

    NARCIS (Netherlands)

    Cui, Y.S.; Du, X.; Weng, L.P.; Zhu, Y.G.

    2008-01-01

    Four soils were collected from different sites of China in Lechang (LC, Guangdong province), Changsha (CS, Hunan province), Jiaxing UX, Zhejiang province) and Hangzhou (HZ, Zhejiang province), and were spiked with Cu (50 mg kg(-1)) and Cd (5 mg kg(-1)). The effects of rice straw addition (6%) on the

  1. Determination of Five Heavy Metals (Cu, Pb, As, Cd, Hg) in Folium Microcotis by Microwave Digestion with Inductively Coupled Plasma Mass Spectrometry%微波消解/ICP-MS法测定布渣叶中5种重金属的含量

    Institute of Scientific and Technical Information of China (English)

    卢鹏; 陈浩桉; 隆颖; 杨立伟; 叶文才; 江仁望

    2011-01-01

    Objective To assay the contents of 5 heavy metals of copper(Cu) , arsenic 1 (As) , cadmium(Cd), hydrargyrum (Hg), plumbum (Pb) in Folium Microcotis by microwave digestion with inductively coupled plasma mass spectrometry(ICP-MS). Methods With germanium(72Ge) , indium(115In) and bismuth(209Bi) as the internal standard substance, the contents of the 5 heavy metals of Cu, Pb, Hg, As and Cd were detected with ICP-MS simultaneously after the samples of Folium Microcotis was treated by microwave digestion. The national standard substance of orange leaves(GBW10020) was used to estimate the accuracy of method. Results For all of the analyzed heavy metals, the correlation coefficient of the calibration curves was over 0.9990, RSD were in the range of 1.1 %~11.6 %, and the recovery rates of the procedure were 97.9 %~108.9 %. Conclusion This method is accurate, convenient, and rapid with high sensitivity, and can be applied to assay the five heavy metals of Cu, Cd, Hg, Pb, As in Folium Microcotis.%目的 采用微波消解电感耦合等离子体质谱(ICP- MS)法测定布渣叶药材中铜(Cu)、铅(Pb)、汞(Hg)、砷(As)、镉(Cd)五种重金属的含量.方法布渣叶经微波消解后,以锗(72Ge)、铟(115In)、铋(209Bi)作为内标物质,用ICP- MS法同时测定样品中Cu、Pb、Hg、As、Cd五种重金属元素的含量.用国家一级标准物质柑橘叶(GBW 10020)评价方法的准确性.结果对于所测元素,校准曲线相关系数r>0.9990回收率为97.9%~108.9%,RSD值在1.1%~11.6%.结论该方法简便、快速、灵敏度高,适合于布渣叶中五种重金属的含量测定.

  2. Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for spectral sensing of Hg, Cd and Pb: A comparative study

    Science.gov (United States)

    Ansari, Zarina; Singha, Shib Shankar; Saha, Abhijit; Sen, Kamalika

    2017-04-01

    A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time ( 20 h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg2 +, Cd2 + and Pb2 +.

  3. Peculiarities of hopping conduction in p-Hg sub 0 sub . sub 7 sub 8 Cd sub 0 sub . sub 2 sub 2 Te crystals at binary doping

    CERN Document Server

    Bogoboyashchij, V V

    2002-01-01

    Electric conductivity and the Hall effect within the 4.2-125 K temperature range have been investigated in p-Hg sub 0 sub . sub 7 sub 8 Cd sub 0 sub . sub 2 sub 2 Te crystals, containing 3 x 10 sup 1 sup 6 cm sup - sup 3 of copper impurities and 1.83 x 10 sup 1 sup 6 cm sup - sup 3 of mercury vacancies (together or separately). The epsilon sub 1 -conductivity due to free holes above 10-12 K and the hopping conductivity below 8-10 K are dominant in such crystals respectively. It was found that the epsilon sub 1 -conductivity in copper-doped crystals is independent of the vacancy presence, while the hopping conductivity essentially increases due to the vacancy availability. This phenomenon is explained in terms hole joining neutral mercury vacancies.The binding energy is calculated; it equal 3.7 meV in background state

  4. Elastic properties of Cs{sub 2}HgBr{sub 4} and Cs{sub 2}CdBr{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kityk, A.V.; Zadorozhna, A.V.; Shchur, Y.I.; Martynyuk-Lototska, Y.I.; Burak, Y.; Vlokh, O.G. [Institute of Physical Optics, Lvov (Ukraine)

    1998-12-31

    Using ultrasonic velocity measurements, all components of the elastic constant matrix C{sub ij} , elastic compliances matrix S{sub ij}, and linear compressibility constants matrix K{sub ij} of orthorhombic Cs{sub 2}HgBr{sub 4} and Cs{sub 2}CdBr{sub 4} crystals have been determined over a wide temperature range, including the region of the phase transition from the normal to the incommensurate phase. Results obtained are considered within the framework of the phenomenological theory. Preliminary analysis of the acoustical properties at room temperature clearly indicates that both crystals are relatively important materials for acousto-optical applications. Copyright (1998) CSIRO Australia 16 refs., 1 tab. 8 figs. The URL for the electronic version of this article is http://www.publish.csiro.au/journals/ajp/electronic.html

  5. Reactive ion etching (RIE) induced p- to n-type conversion in extrinsically doped p-type HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Musca, C.A.; Smith, E.P.G.; Siliquini, J.F.; Dell, J.M.; Antoszewski, J.; Faraone, L. [Univ. of Western Australia, Nedlands, Western Australia (Australia). Dept. of Electrical and Electronic Engineering; Piotrowski, J. [Vigo System Ltd., Warsaw (Poland)

    1998-12-31

    Mercury annealing of reactive ion etching (RIE) induced p- to n-type conversion in extrinsically doped p-type epitaxial layers of HgCdTe (x = 0.31) has been used to reconvert n-type conversion sustained during RIE processing. For the RIE processing conditions used (400 mT, CH{sub 4}/H{sub 2}, 90 W) p- to n-type conversion was observed using laser beam induced current (LBIC) measurements. After a sealed tube mercury anneal at 200 C for 17 hours, LBIC measurements clearly indicated no n-type converted region remained. Subsequent Hall measurements confirmed that the material consisted of a p-type layer, with electrical properties equivalent to that of the initial as-grown wafer (N{sub A}-N{sub D} = 2 {times} 10{sup 16} cm{sup {minus}3}, {mu} = 350 cm{sup 2}.V{sup {minus}1}.s{sup {minus}1}).

  6. First and second harmonic generation of the XAl{sub 2}Se{sub 4} (X=Zn,Cd,Hg) defect chalcopyrite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ouahrani, Tarik, E-mail: tarik_ouahrani@yahoo.fr [Laboratoire de Physique Theorique, Universite de Tlemcen, B.P.230,13000 Tlemcen (Algeria); Ecole Preparatoire en Sciences et Techniques, Depertement de Physique EPST-T, Tlemcen 13000 (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Universite de Mascara, 29000 Mascara (Algeria); Lasri, B. [Laboratoire de Physique Theorique, Universite de Tlemcen, B.P.230,13000 Tlemcen (Algeria); Universite Dr Tahar Moulay de Saida, B.P. 138, Cite el Nasr, Saida 20000 (Algeria); Reshak, Ali H. [School of Complex systems, FFPW- South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Bouhemadou, A. [Department of Physics, Faculty of Sciences, University of Setif, 19000 Setif (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2012-09-15

    The chemical bonding of the ZnAl{sub 2}Se{sub 4}, CdAl{sub 2}Se{sub 4} and HgAl{sub 2}Se{sub 4} defect chalcopyrites has been studied in the framework of the quantum theory of atoms in molecules (AIM). The GW quasi-particle approximation is used to correct the DFT-underestimation of energy gap, and as a consequence the linear and nonlinear optical properties are significantly enhanced. The second harmonic generation (SHG) displays certain dependence with the ionicity degree decrease through the dependency of the SHG on the band gap. The occurrence of the AIM saddle point is characterized and some clarifying features in relationship with the density topology are exposed, which enable to understand the relation with the second harmonic generation effect.

  7. AB INITIO INVESTIGATION OF 12-CROWN-4 AND BENZO-12-CROWN-4 COMPLEXES WITH Li+, Na+, K+, Zn2+, Cd2+, AND Hg2+

    Directory of Open Access Journals (Sweden)

    Yahmin Yahmin

    2010-06-01

    Full Text Available The structure and binding energies of 12-crown-4 and benzo-12-crown-4 complexes with Li+, Na+, K+, Zn2+, Cd2+, and Hg2+were investigated with ab initio calculations using Hartree-Fock approximation and second-order perturbation theory. The basis set used in this study is lanl2mb. The structure optimization of cation-crown ether complexes was evaluated at HF/lanl2mb level of theory and interaction energy of the corresponding complexes was calculated at MP2/lanl2mb level of theory (MP2/lanl2mb//HF/lanl2mb. Interactions of the crown ethers and the cations were discussed in term of the structure parameter of crown ether. The binding energies of the complexes show that all complex formed from transition metal cations is more stable than the complexes formed from alkali metal cations.   Keywords: 12-crown-4, benzo-12-crown-4, alkali metals, transition metals

  8. Cation recognition of thiacalix[2]thianthrene and p-tert-butylthiacalix[2]thianthrene and their conformers and complexes with Zn(II), Cd(II) and Hg(II): a theoretical investigation.

    Science.gov (United States)

    Kaenkaew, Saowapak; Sae-Khow, Ornchuree; Ruangpornvisuti, Vithaya

    2010-02-01

    The structures of thiacalix[2]thianthrene, p-tert-butylthiacalix[2]thianthrene and their complexes with Zn(2+), Cd(2+) and Hg(2+) were obtained using B3LYP/LanL2DZ and HF/LanL2DZ calculations. The structures of the most stable conformers of thiacalix[2]thianthrene and p-tert-butylthiacalix[2]thianthrene optimized at either the B3LYP/LanL2DZ or HF/LanL2DZ level are in good agreement with their corresponding X-ray crystallographic structures. The binding energies of cations, Zn(2+), Cd(2+) and Hg(2+) to thiacalix[2]thianthrene and to p-tert-butylthiacalix[2]thianthrene conformers, and the thermodynamic properties of their associations were obtained. The relative selectivities of both thiacalix[2]thianthrene and thiacalix[2]thianthrene conformer are in same order: Zn(2+) > Hg(2+) > Cd(2+).

  9. Evaluation of Integrated Time-Temperature Effect in Pyrolysis Process of Historically Contaminated Soils with Cadmium (Cd and Lead (Pb

    Directory of Open Access Journals (Sweden)

    Bulmău C

    2013-04-01

    Full Text Available It is already known that heavy metals pollution causes important concern to human and ecosystem health. Heavy metals in soils at the European level represents 37.3% between main contaminates affecting soils (EEA, 2007. This paper illustrates results obtained in the framework of laboratory experiments concerning the evaluation of integrated time-temperature effect in pyrolysis process applied to contaminated soil by two different ways: it is about heavy metals historically contaminated soil from one of the most polluted areas within Romania, and artificially contaminated with PCB-containing transformer oil. In particular, the authors focused on a recent evaluation of pyrolysis efficiency on removing lead (Pb and cadmium (Cd from the contaminated soil. The experimental study evaluated two important parameters related to the studied remediation methodology: thermal process temperature and the retention time in reactor of the contaminated soils. The remediation treatments were performed in a rotary kiln reactor, taking into account three process temperatures (400°C, 600°C and 800°C and two retention times: 30 min. and 60 min. Completed analyses have focused on pyrolysis solids and gas products. Consequently, both ash and gas obtained after pyrolysis process were subjected to chemical analyses.

  10. Latest developments of 10μm pitch HgCdTe diode array from the legacy to the extrinsic technology

    Science.gov (United States)

    Péré-Laperne, Nicolas; Berthoz, Jocelyn; Taalat, Rachid; Rubaldo, Laurent; Kerlain, Alexandre; Carrère, Emmanuel; Dargent, Loïc.

    2016-05-01

    Sofradir recently presented Daphnis, its latest 10 μm pitch product family. Both Daphnis XGA and HD720 are 10μm pitch mid-wave infrared focal plane array. Development of small pixel pitch is opening the way to very compact products with a high spatial resolution. This new product is taking part in the HOT technology competition allowing reductions in size, weight and power of the overall package. This paper presents the recent developments achieved at Sofradir to make the 10μm pitch HgCdTe focal plane array based on the legacy technology. Electrical and electro-optical characterizations are presented to define the appropriate design of 10μm pitch diode array. The technological tradeoffs are explained to lower the dark current, to keep high quantum efficiency with a high operability above 110K, F/4. Also, Sofradir recently achieved outstanding Modulation Transfer Function (MTF) demonstration at this pixel pitch, which clearly demonstrates the benefit to users of adopting 10μm pixel pitch focal plane array based detectors. Furthermore, the HgCdTe technology has demonstrated an increase of the operating temperature, plus 40K, moving from the legacy to the P-on-n one at a 15μm pitch in mid-wave band. The first realizations using the extrinsic P-on-n technology and the characterizations of diodes with a 10μm pitch neighborhood will be presented in both mid-wave and long-wave bands.

  11. Concentración de Hg, Pb, Cd, Cr y As en hígado de Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae capturado en Veracruz, México

    Directory of Open Access Journals (Sweden)

    Fernando Mendoza-Díaz

    2013-06-01

    Full Text Available La contaminación de los ecosistemas marinos y costeros por metales pesados en el Golfo de México es uno de los problemas que afectan a los recursos naturales del medio acuático. Los tiburones por situarse en niveles tróficos superiores de la red alimenticia acumulan y magnifican cantidades considerables de contaminantes. Por esta razón, el objetivo de este trabajo fue determinar la concentración de cuatro metales pesados (Hg, Cd, Pb y Cr y un metaloide (As en el tiburón punta negra (Carcharhinus limbatus por medio de espectrofotometría de absorción atómica con flama y generador de hidruros. Se muestrearon 19 hígados de tiburones capturados cerca de Tamiahua, Veracruz entre noviembre 2007 y marzo 2008, de los cuales 12 fueron machos adultos, una hembra adulta, tres machos jóvenes y tres hembras jóvenes. Las concentraciones máximas registradas para cada metal fueron: Hg=0.69mg/ kg, Cd=0.43mg/kg, As=27.37mg/kg, Cr=0.35mg/kg. El Pb no fue detectado, no al menos la cantidad mínima de detección requerida por el espectrofotómetro de absorción atómica (0.1mg/kg. Ninguna de las muestras analizadas rebasó los límites máximos permisibles por las leyes mexicanas y americanas.

  12. Model optimization of cadmium and accumulation in switchgrass (Panicum virgatum L.): potential use for ecological phytoremediation in Cd-contaminated soils.

    Science.gov (United States)

    Wang, Quanzhen; Gu, Muyu; Ma, Xiaomin; Zhang, Hongjuan; Wang, Yafang; Cui, Jian; Gao, Wei; Gui, Jing

    2015-11-01

    Soil pollution with heavy metals is an increasingly serious threat to the environment, food security, and human health. Therefore, it is urgent to develop economic and highly efficient soil restoration technology for environmental improvement; phytoremediation is an option that is safe, has low cost, and is environmentally friendly. However, in selecting hyperaccumulators or tolerant plants, theories and operation technologies for optimal restoration should be satisfied. In this study, the switchgrass growth response and performance of phytoextraction under the coupling effect of Cd and pH were investigated by evaluating seed germination, seedling growth, and the Cd content in the plant to evaluate the potential use of switchgrass as a phytoremediation plant in cadmium contaminated soil. This study conducted three sets of independent experiments with five levels of Cd concentrations, including two orthogonal matrix designs of combining Cd with pH values. The results showed that switchgrass was germinated well under all treatments (Cd concentration of 0-500 μM), but the seedling growth was significantly affected by Cd and pH, as shown by multivariate regression analyses. Hormesis was found during the growth of switchgrass plants exposed to low Cd concentrations under hydroponic conditions, and switchgrass plants were capable of developing with a Cd concentration of 100-175 μM and pH of 4.1-5.9. Mild acidic conditions can enhance the ability of Cd to accumulate in switchgrass. Switchgrass was moderately tolerant to Cd and may be used as a phytoremediation plant for Cd-contaminated soils in the future. Our results also suggest that hormetic effects should be taken into consideration in the phytoremediation of Cd-contaminated soils. We discuss the physiological and biochemical mechanisms contributing to the effective application of the plant for the phytoremediation of Cd-contaminated soils.

  13. Synthesis, Characterization and in Vitro Antibacterial Activities of CdO Nanoparticle and Nano-sheet Mixed-ligand of Cadmium(ІІ Complex

    Directory of Open Access Journals (Sweden)

    Zohreh Rashidi Ranjbar

    2016-07-01

    Full Text Available Here, we report the synthesis of a Schiff-base mixed-ligand complex of cadmium(ІІ in bulk and nano-scales via the precipitation and sonochemical methods, respectively. The complex formula is [Cd(3-bpdh(3-bpdbCl2]n (1, where the ligands are 3-bpdh = 2,5-bis(3-pyridyl-3,4-diaza-2,4-hexadiene and 3-bpdb = 1,4-bis(3-pyridyl-2,3-diaza-1,3-butadiene. The structure of mixed-ligand complex (1 was characterized by IR, 1H NMR and elemental analyses. Cadmium(ІІ oxide nanoparticles were prepared by direct thermolysis from nanosheet of complex (1. The cadmium(ІІ oxide structure was characterized by X-ray Diffraction (XRD and Energy Dispersive X-ray  analyses (EDAX. Size, morphology and structural dispersion of all obtained nanostructures were characterized by Scanning Electron Microscopy (SEM. The Schiff-base ligands, bulk and nano-scales of complex (1 and cadmium(ІІ oxide nanoparticles were analyzed for antibacterial activities against Bacillus alvei (bacteria causing the honey bee European foulbrood disease. The Minimum Inhibitory Concentrations (MIC has been shown moderate antibacterial activities compared with some other standard drugs. Known antibiotics like penicillin and SXT (Trimethoprim/sulfamethoxazole were used as positive control.

  14. Effects of zinc on cadmium uptake by spring wheat (Triticum aestivum, L.): long-time hydroponic study and short-time 109Cd tracing study

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhong-qiu; ZHU Yong-guan; CAI Yun-long

    2005-01-01

    To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 h) (Experiment 2) were conducted. In Experiment 1, spring wheat (cv. Brookton) was grown in nutrient solution at uniform cadmium concentration of 20μ mol/L and 10 zinc concentrations (0, 1, 5, 10, 20, 100, 200, 500, 1000, 2000 μ mol/L). In Experiment 2, spring wheat seedlings,pre-cultivated in complete nutrient solution, were treated with 109Cd of uniform activity and the same series of Zn concentrations as those in Experiment 1 for 24 h. Cd concentrations in shoots and roots in Experiment 1 increased marginally but not consistently with Zn increasing at Zn rates of 1~200 μmol/L, and then decreased significantly at high rates (>200 μ mol/L). In Experiment 2, the response of 109Cd activities in shoots and roots to increasing Zn was greatly similar to the response of Cd concentrations to Zn increasing in Experiment 1. The results of the two experiments indicated that the short-time and long-time exposure of spring wheat to Zn had similar effects on Cd accumulation.

  15. Cadmium telluride quantum dots (CdTe-QDs) and enhanced ultraviolet-B (UV-B) radiation trigger antioxidant enzyme metabolism and programmed cell death in wheat seedlings.

    Science.gov (United States)

    Chen, Huize; Gong, Yan; Han, Rong

    2014-01-01

    Nanoparticles (NPs) are becoming increasingly widespread in the environment. Free cadmium ions released from commonly used NPs under ultraviolet-B (UV-B) radiation are potentially toxic to living organisms. With increasing levels of UV-B radiation at the Earth's surface due to the depletion of the ozone layer, the potential additive effect of NPs and UV-B radiation on plants is of concern. In this study, we investigated the synergistic effect of CdTe quantum dots (CdTe-QDs), a common form of NP, and UV-B radiation on wheat seedlings. Graded doses of CdTe-QDs and UV-B radiation were tested, either alone or in combination, based on physical characteristics of 5-day-old seedlings. Treatments of wheat seedlings with either CdTe-QDs (200 mg/L) or UV-B radiation (10 KJ/m(2)/d) induced the activation of wheat antioxidant enzymes. CdTe-QDs accumulation in plant root cells resulted in programmed cell death as detected by DNA laddering. CdTe-QDs and UV-B radiation inhibited root and shoot growth, respectively. Additive inhibitory effects were observed in the combined treatment group. This research described the effects of UV-B and CdTe-QDs on plant growth. Furthermore, the finding that CdTe-QDs accumulate during the life cycle of plants highlights the need for sustained assessments of these interactions.

  16. Cadmium telluride quantum dots (CdTe-QDs and enhanced ultraviolet-B (UV-B radiation trigger antioxidant enzyme metabolism and programmed cell death in wheat seedlings.

    Directory of Open Access Journals (Sweden)

    Huize Chen

    Full Text Available Nanoparticles (NPs are becoming increasingly widespread in the environment. Free cadmium ions released from commonly used NPs under ultraviolet-B (UV-B radiation are potentially toxic to living organisms. With increasing levels of UV-B radiation at the Earth's surface due to the depletion of the ozone layer, the potential additive effect of NPs and UV-B radiation on plants is of concern. In this study, we investigated the synergistic effect of CdTe quantum dots (CdTe-QDs, a common form of NP, and UV-B radiation on wheat seedlings. Graded doses of CdTe-QDs and UV-B radiation were tested, either alone or in combination, based on physical characteristics of 5-day-old seedlings. Treatments of wheat seedlings with either CdTe-QDs (200 mg/L or UV-B radiation (10 KJ/m(2/d induced the activation of wheat antioxidant enzymes. CdTe-QDs accumulation in plant root cells resulted in programmed cell death as detected by DNA laddering. CdTe-QDs and UV-B radiation inhibited root and shoot growth, respectively. Additive inhibitory effects were observed in the combined treatment group. This research described the effects of UV-B and CdTe-QDs on plant growth. Furthermore, the finding that CdTe-QDs accumulate during the life cycle of plants highlights the need for sustained assessments of these interactions.

  17. Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

    KAUST Repository

    Saliba, Daniel

    2016-06-23

    Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

  18. Diverse strategies conferring extreme cadmium (Cd) tolerance in the dark septate endophyte (DSE), Exophiala pisciphila: evidence from RNA-seq data.

    Science.gov (United States)

    Zhao, Dake; Li, Tao; Shen, Mi; Wang, Junling; Zhao, Zhiwei

    2015-01-01

    Dark septate endophytes (DSE) ubiquitously colonize the roots of plants growing in extreme heavy metals (HMs)-contaminated soils. Little is known about the overall molecular response of DSE to excessive HMs. Therefore, RNA-seq was performed through Illumina Hiseq 2000 sequencing based on two cDNA libraries of the DSE strain Exophiala pisciphila, cultured under cadmium (Cd)-free and Cd-stressed conditions, and 21,376 unigenes were generated. In total, 575 differentially expressed genes (DEGs) were obtained. Approximately 40% of the DEGs (228 unigenes) were involved in 10 well-known HMs-tolerant pathways, conferring the extreme cadmium (Cd) tolerance of E. pisciphila, including metal ion binding and transportation, organic acid metabolism and transportation, reactive oxygen species (ROS) scavenging, redox homeostasis, transcription factors production, sulfate assimilation, DNA repair and cell wall integrity maintenance, etc. Our results indicate that integral tactics associated with the collaboration of extracellular and intracellular mechanisms contribute to the enhanced HMs tolerance of this fungus. This study represents the first investigation of the transcriptome of DSE under Cd stress, and our results provide valuable information for future molecular studies of HMs tolerance in fungi.

  19. Synthesis, characterization and thermal studies of Zn(II), Cd(II) and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate: the single crystal structure of [(C(6)H(5))(CH(3))NCS(2)](4)Hg(2).

    Science.gov (United States)

    Onwudiwe, Damian C; Ajibade, Peter A

    2011-01-01

    Zn(II), Cd(II) and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate have been synthesized and characterized by elemental analysis and spectral studies (IR, (1)H and (13)C-NMR). The single crystal X-ray structure of the mercury complex revealed that the complex contains a Hg centre with a distorted tetrahedral coordination sphere in which the dinuclear Hg complex resides on a crystallographic inversion centre and each Hg atom is coordinated to four S atoms from the dithiocarbamate moiety. One dithiocarbamate ligand acts as chelating ligand while the other acts as chelating bridging ligand between two Hg atoms, resulting in a dinuclear eight-member ring. The course of the thermal degradation of the complexes has been investigated using thermogravimetric and differential thermal analyses techniques. Thermogravimetric analysis of the complexes show a single weight loss to give MS (M = Zn, Cd, Hg) indicating that they might be useful as single source precursors for the synthesis of MS nanoparticles and thin films.

  20. Evaluation of low-cadmium ZnCdSeS alloyed quantum dots for remote phosphor solid-state lighting technology.

    Science.gov (United States)

    Siffalovic, Peter; Badanova, Dominika; Vojtko, Andrej; Jergel, Matej; Hodas, Martin; Pelletta, Marco; Sabol, Dusan; Macha, Marek; Majkova, Eva

    2015-08-10

    We report on the possibility to enhance color rendering of commercially available remote phosphor light-emitting diode modules by using low-cadmium content ZnCdSeS alloyed quantum dots. The employed numerical simulations showed that the color-rendering index of 90+ at the color-correlated temperature of 3200 K can be achieved by application of a single layer of quantum dots onto a neutral-white remote phosphor substrate. The experimental results fully support the numerical calculations, thus revealing the only limiting factor in achieving a higher photometric performance: the self-absorption effect in quantum dots. The presented low-cadmium content quantum dots allow a price-effective upgrade of already existing remote phosphor solid-state lighting technology toward a higher color-rendering capability.

  1. A field-scale study of cadmium phytoremediation in a contaminated agricultural soil at Mae Sot District, Tak Province, Thailand: (1) Determination of Cd-hyperaccumulating plants.

    Science.gov (United States)

    Khaokaew, Saengdao; Landrot, Gautier

    2015-11-01

    The cadmium (Cd) phytoremediation capabilities of Gynura pseudochina, Chromolaena odorata, Conyza sumatrensis, Crassocephalum crepidioides and Nicotiana tabacum were determined by conducting in-situ experiments in a highly Cd-contaminated agricultural field at Mae Sot District, Tak Province, Thailand. Most of these five plant species, which are commonly found in Thailand, previously demonstrated Cd-hyperaccumulating capacities under greenhouse conditions. This study represented an important initial step in determining if any of these plants could, under field-conditions, effectively remove Cd from the Mae Sot contaminated fields, which represent a health threat to thousands of local villagers. All plant species had at least a 95% survival rate on the final harvest day. Additionally, all plant species, except C. odorata, could hyperaccumulate the extractable Cd amounts present in the soil, based on their associated Bioaccumulation Factor (BAF), Translocation Factor (TF), and background Vegetation Factor (VF). Therefore, the four Cd-hyperaccumulating plant species identified in this study may successfully treat a majority of contaminated fields at Mae Sot, as it was previously reported that Cd amounts present in a number of these soils were mostly available.

  2. First-principles prediction of a novel cadmium disulfide monolayer (penta-CdS2): Indirect to direct band gap transition by strain engineering

    Science.gov (United States)

    Naseri, Mosayeb

    2017-10-01

    Using first principles calculation a novel two dimensional structure of Cadmium Disulfide (penta-CdS2) is predicted. The calculated cohesive energy of -3.61 eV/atom indicates the thermodynamic stability of the predicted monolayer. Furthermore, the kinetic stability of the monolayer is examined by phonon dispersion calculation. According to our calculations, penta-CdS2 monolayer is a semiconductor with an indirect band gap of 2.97 eV, which can be effectively engineered by employing external biaxial compressive and tensile strain, The results emphasize that penta-CdS2 monolayer as a wide band gap semiconductor can become a promising material for application in new generation of nano-optoelectronic devices.

  3. PVA-Fe(Ⅲ)、Zn(Ⅱ)、Cd(Ⅱ)、Hg(Ⅱ)配合物的合成、表征及抗菌性能%Synthesis, Characterization and Anti-bacterial Activity of PVA-Fe(Ⅲ), Zn(Ⅱ), Cd(Ⅱ), Hg(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    吴之传; 张宇东; 陈培根; 周凯; 陶庭先

    2008-01-01

    以聚乙烯醇(PVA)为高分子配体,与金属离子在溶液中进行配位反应,合成了PVA-Fe(Ⅲ)、PVA-Zn(Ⅱ)、PVA-Cd(Ⅱ)、PVA-Hg(Ⅱ)配合物.通过IR、Raman和XPS测试技术对配合物进行表征.IR结果显示,各配合物νc-o从纯PVA的1094cm-1向低波数方向移动8~11cm-1,νc-c由纯PVA的1430cm-1向低波数方向移动3~8cm-1;Raman显示,PVA-re(Ⅲ)、PVA-Zn(Ⅱ)、PVA-Cd(Ⅱ)、PVA-Hg(Ⅱ)配合物均在200~400cm-1处出现金属-氧键新峰;PVA-Fe(Ⅲ)的XPS显示O1s(533.0ev)、C1s(285.0eV)、Fe2p(712.0eV)的结合能与PVA[O1s(532.5eV)、C1s(284.6eV)]及FeCl3[Fe2p(711.2eV)]比较,发生了显著变化.以上结果表明,PVA分子侧链上的羟基氧提供孤对电子对与金属离子的空轨道形成配位键.配合物的抗菌实验结果显示,PVA-Hg(Ⅱ)对大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌具有很强的灭菌效果,PVA-Zn(Ⅱ)的灭菌效果较弱.

  4. Metales pesados (Pb, Cd, Cr y Hg en población general adulta próxima a una planta de tratamiento de residuos urbanos de Bizkaia

    Directory of Open Access Journals (Sweden)

    Miren Begoña Zubero Oleagoitia

    2008-01-01

    Full Text Available Fundamento: Entre las posibles emisiones de una planta de valorización energética de residuos sólidos urbanos (PVERSU se encuentran los metales pesados. el objetivo del estudio es conocer los niveles en sangre y orina de metales pesados en población general de Bizkaia. Métodos: En 2006 se midió la exposición a Pb en 95 muestras de sangre y Cd, Cr y Hg en 93 muestras de orina de adultos de la población general de Bizkaia, País Vasco, obtenidas de dos áreas con alta densidad de tráfico del área metropolitana de Bilbao en la cercanía de una PVERSU que iniciaba su actividad, una tercera correspondiente a una zona urbana de Bilbao con tráfico denso y alejada del área de influencia de las posibles emisiones de la PVERSU y la cuarta alejada de la planta y con baja densidad de tráfico. De cada área se estableció como objetivo elegir a un mínimo 20 participantes, la mitad de cada sexo y, a su vez, la mitad de 20 a 44 años y la mitad de 45 a 69. Se utilizó la prueba de la c2 para estudiar la asociación entre variables categóricas. Como prueba de comparación de medias se utilizó la t de Student y la ANOVA para variables con dos o más categorías, respectivamente. Para ajustar factores de confusión se utilizó un modelo de regresión lineal múltiple. Resultados: Las concentraciones medias fueron PbS: 2,68 ¿g/100ml, CdU 0,54 ug/g creatinina, CrU: 0,51 uig/g creatinina, y HgU: 0,65 ug/g creatinina. Conclusión: No se observaron diferencias entre las zonas. El análisis unifactorial y multifactorial mostró que los niveles de PbS se incrementaban con la edad y estaban asociados con el consumo de productos locales de huerta y con el trabajo en la metalurgia. La edad eleva los niveles de CdU y se observa en clases sociales altas niveles más elevados, así como en mujeres y en personas fumadoras. Los niveles de CrU eran más elevados en zonas alejadas a la PVERSU y en las clases altas. Los niveles de HgU fueron más elevados en

  5. Cd4As2Br3

    Directory of Open Access Journals (Sweden)

    Mohammed Kars

    2014-03-01

    Full Text Available Single crystals of Cd4As2Br3 (tetracadmium biarsenide tribromide were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I and contains two independent As atoms on special positions with site symmetry -3 and two independent Cd atoms, of which one is on a special position with site symmetry -3. The Cd4As2Br3 structure consists of AsCd4 tetrahedra sharing vertices with isolated As2Cd6 octahedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd...Br contacts.

  6. Crystal structure, DNA interaction and thermal analysis data of two new antimicrobial active binuclear cadmium and mercury complexes

    Science.gov (United States)

    Musavi, S. A.; Montazerozohori, M.; Masoudiasl, A.; Naghiha, R.; Joohari, S.; Assoud, A.

    2017-10-01

    Two new binuclear Schiff base complexes with the general formula [CdLBr(μ-Br)]2 (1) and [Hg2L(μ-I)2I2] (2) were prepared by the reaction of 2,2-dimethyl-N,N'- bis-(3-phenyl-allylidene)-propane-1,3-diamine (L), CdBr2 and HgI2. The crystal structure of two complexes was determined by X-ray crystallography. The common structures for four-coordinated compounds are square planar or the tetrahedral geometries, which is evaluated by the Houser angular index (τ4). In [CdLBr(μ-Br)]2 (1), each cadmium center is five-coordinated by two iminic nitrogen atoms from Schiff base ligand, two μ2-bridging bromide anions and one terminal coordinating bromide anion. The metal center in this centrosymmetric dimer has a distorted square-pyramidal geometry. [Hg2L(μ-I)2I2] (2) consists of two four-coordinated mercury centers with different coordination spheres (HgN2I2 for Hg1 and HgI4 for Hg2). The TG/DTG diagrams showed that both complexes were completely decomposed under a nitrogen atmosphere. Furthermore, antibacterial activities of compounds have been screened against various bacteria and fungi by Disk diffusion method. Mercury complex inhibited the growth of the microorganisms more efficient than cadmium complex. DNA cleavage potential of compounds was evaluated by agarose gel electrophoresis method. Finally, nano-structure cadmium complex was sono-chemically synthesized and applied as precursor for preparation of cadmium oxide nanoparticles.

  7. A discrete element model of laser beam induced current (LBIC) due to the lateral photovoltaic effect in open-circuit HgCdTe photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Fynn, K.A.; Faraone, L. [Univ. of Western Australia, Nedlands (Australia). Dept. of Electrical and Electronic Engineering; Bajaj, J. [Rockwell International Science Center, Thousand Oaks, CA (United States)

    1995-10-01

    The non-destructive optical characterization technique of Laser-Beam-Induced-Current (LBIC) imaging has proven useful in qualitatively assessing electrically active defects and localized non-uniformities in HgCdTe materials and devices used for infrared photovoltaic arrays. To further the development of a quantitative working model for LBIC, this paper focuses on the application of the technique to photovoltaic structures that are represented by a discrete element equivalent circuit. For this particular case the LBIC signal arises due to the lateral photovoltaic effect in non-uniformly illuminated open-circuit photodiodes. The outcomes of the model predict all of the experimentally observed geometrical features of the LBIC image and signal. Furthermore, the model indicates that the LBIC signal has an extremely weak dependence on the p-n junction reverse saturation current, and shows a linear dependence with laser power. This latter feature may be useful for non-contact measurement of the quantum efficiency of individual photodiodes within a large two-dimensional focal plane array. The decay of the LBIC signal outside the physical boundary of the p-n junction is of the same form as the roll-off in the short circuit photoresponse and, therefore, can be used to extract the diffusion length of minority carriers. Experimental data are obtained from an arsenic implanted p-on-n junction fabricated on MBE grown Hg{sub 1{minus}x}Cd{sub x}Te material with an x-value of 0.3. The p-on-n diode is shown to be uniform and of high quality with an R{sub o}A product of 1 {times} 10{sup 8} {Omega}{center_dot}cm{sup 2} at 77 K. The validity of the simple model developed in this paper, is confirmed by the excellent agreement with experimental results. Consequently, the LBIC technique is shown to be an appropriate diagnostic tool for non-contact quantitative analysis of semiconductor materials and devices.

  8. Determination of cadmium, lead and mercury residual levels in meat of canned light tuna (Katsuwonus pelamis and Thunnus albacares) and fresh little tunny (Euthynnus alletteratus) in Libya.

    Science.gov (United States)

    Abolghait, S K; Garbaj, A M

    2015-01-01

    Surveillance for mercury (Hg), lead (Pb) and cadmium (Cd) contamination in tuna products is crucial for consumer food safety. Hg, Pb and Cd contaminants were monitored in a total of 60 specimens of fresh little tunny (Euthynnus alletteratus) and popular brands of skipjack and yellowfin (Katsuwonus pelamis and Thunnus albacares) canned tuna commercially available in Tripoli, Libya. Direct Mercury Analyzer (DMA-80) was implemented for determination of total Hg level and graphite furnace atomic absorption spectrometry (GFAAS) was employed for determination of Cd and Pb concentrations. The results indicated that Hg had the highest concentration level and Cd had the lowest concentration level either in tested canned tuna or fresh little tunny samples. The average concentration of Hg in fresh little tunny samples was 1.185 ± 0.968 mg kg(-1) wet weight (ww) and often exceeded the standard permissible limit. In addition, canned yellowfin tuna had the lowest levels of Cd (0.027 ± 0.026 mg kg(-1) ww), Pb (0.075 ± 0.071) and Hg (0.163 ± 0.122 mg kg(-1) ww). Results of the current surveillance indicated that canned skipjack and yellowfin tuna sold in Tripoli markets show contaminant levels well under the European thresholds adopted for Cd, Pb and Hg. However, consumption of large quantities of Mediterranean little tunny products significantly increases human exposure to the risk of Hg toxicity.

  9. Zinc and cadmium monosalicylates

    Energy Technology Data Exchange (ETDEWEB)

    Kharitonov, Yu.Ya.; Tujebakhova, Z.K. (Moskovskij Khimiko-Tekhnologicheskij Inst. (USSR))

    1984-06-01

    Zinc and cadmium monosalicylates of the composition MSal, where M-Zn or Cd, Sal - twice deprotonated residue of salicylic acid O-HOC/sub 6/H/sub 4/COOH (H/sub 2/Sal), are singled out and characterized. When studying thermograms, thermogravigrams, IR absorption spectra, roentgenograms of cadmium salicylate compounds (Cd(OC/sub 6/H/sub 4/COO) and products of their thermal transformations, the processes of thermal decomposition of the compounds have been characterized. The process of cadmium monosalicylate decomposition takes place in one stage. Complete loss of salicylate acido group occurs in the range of 320-460 deg. At this decomposition stage cadmium oxide is formed. A supposition is made that cadmium complex has tetrahedral configuration, at that, each salicylate group plays the role of tetradentate-bridge ligand. The compound evidently has a polymer structure.

  10. Lead, mercury, and cadmium in umbilical cord serum and birth outcomes in Chinese fish consumers.

    Science.gov (United States)

    Tang, Mengling; Xu, Chenye; Lin, Nan; Liu, Kai; Zhang, Yongli; Yu, Xinwei; Liu, Weiping

    2016-04-01

    Heavy metals such as lead (Pb), mercury (Hg), and cadmium (Cd) were detected in the islands of Yangtze River estuary and Hangzhou bay and their exposure caused potential health risk for the residents. To assess the exposure levels of Pb, Hg, and Cd, the umbilical cord serum samples were collected from 103 mother-newborn pairs as the noninvasive specimens. The association of the concentration of Pb, Hg, and Cd with the birth outcomes was evaluated. Pb, Hg, and Cd had high exposure levels with the median concentrations at 76.20 μg L(-1) [interquartile range (IQR): 44.71, 115.80], 21.94 μg L(-1) (IQR: 15.10, 27.64), and 6.36 μg L(-1) (IQR: 3.63, 13.34), respectively. A unit increase in the Pb umbilical cord serum concentration (μg L(-1)) was significantly associated with a 0.29 cm (95% CI: -0.50, -0.09) decrease in birth height and a 0.22 cm (95%CI: -0.44, 0.00) decrease in head circumference. The middle tertile Pb and Hg exposure levels were found significantly negative effects on birth outcomes compared with low tertile exposure levels. Exposure to Cd showed no apparent effect on birth outcomes. Our results suggested that Pb and Hg exposure has potential adverse effects on birth outcomes in Chinese fish consumers from Yangtze River outlet and Hangzhou bay estuary regions.

  11. Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

    Directory of Open Access Journals (Sweden)

    S. Bensalem

    2016-12-01

    Full Text Available Through first-principles calculation based on the density functional theory (DFT within the pseudo potential-plane wave (PP-PW approach, we studied the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials. The calculated lattice parameters are in good agreement with experimental and theoretical reported data. The elastic constants are calculated for both compounds using the static finite strain scheme. The hydrostatic pressure action on the elastic constants predicts that both materials are mechanically stable up to 10 GPa. The polycrystalline mechanical parameters, i.e., the anisotropy factor (A, bulk modulus (B, shear modulus (G, Young's modulus (E, Lame's coefficient (λ and Poisson's ratio (ν have been estimated from the calculated single crystal elastic constants. The analysis of B/G ratio shows that the two studied compounds behave as ductile. Based on the calculated mechanical parameters, the Debye temperature and the thermal conductivity have been probed. In the framework of the quasi-harmonic approximation, the temperature dependence of the lattice heat capacity of both crystals has been investigated.

  12. Photocatalytic removal of M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) over new catalyst CuCrO(2).

    Science.gov (United States)

    Ketir, W; Bouguelia, A; Trari, M

    2008-10-30

    The metal ions M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) are potentially toxic. Their electro deposition has been carried out in aqueous air-equilibrated CuCrO(2) suspension upon visible illumination. The delafossite CuCrO(2) is p-type semiconductor characterized by a low band gap (1.28 eV) and a long-term chemical stability. The corrosion rate is found to be 10(-2) micromol m(-2)month(-1) in aqua regia. The oxide has been elaborated through nitrate route where the specific surface area is increased via the surface/bulk ratio. A correlation exists between the dark M(2+) adsorption, the redox potential of M(2+/0) couple and the conduction band of CuCrO(2) positioned at -1.06 V(SCE). Ag(+) cannot be photoreduced because of its positive potential located far above the valence band. By contrast, Zn(2+) is efficiently deposited due to the large driving force at the interface. The improved photoactivity of copper with a deposition percentage (90%) is attributed to the strong dark adsorption onto the surface catalyst. The results indicate a competitive effect with the water reduction; it has been observed that the M(2+) deposition goes parallel with the hydrogen evolution. Such behavior is attributed to the low H(2) over voltage when ultra fine aggregate of M islands are photodeposited onto CuCrO(2) substrate.

  13. The isotypic family of the diarsenates MM'As{sub 2}O{sub 7} (M = Sr, Ba; M' = Cd, Hg)

    Energy Technology Data Exchange (ETDEWEB)

    Weil, Matthias [Technische Univ. Wien (Austria). Inst. for Chemical Technologies and Analytics

    2016-08-01

    The diarsenates MM'As{sub 2}O{sub 7} (M = Sr, Ba; M' = Cd, Hg) were prepared under hydrothermal conditions (∝200 C, autogenous pressure), starting from As{sub 2}O{sub 5} and the corresponding metal oxides or precursor compounds thereof in aqueous solutions. Structure analyses on the basis of single crystal X-ray data revealed the four structures to be isotypic. They are the first diarsenates to crystallize in the triclinic BaZnP{sub 2}O{sub 7} structure type (space group P anti 1, Z = 2, a ∼ 5.8 Aa, b ∼ 7.3 Aa, c ∼ 7.6 Aa, α ∼ 101 , β ∼ 91 , γ ∼ 98 ). All related MM'As{sub 2}O{sub 7} diarsenates reported so far (M = Sr, Ba, Pb; M' = Mg, Co, Cu, Zn) crystallize in the monoclinic α-Ca{sub 2}P{sub 2}O{sub 7} structure type (P2{sub 1}/n, Z = 4). Hence, the size of the divalent M' cation determines which of the two structure types is adopted.

  14. Can heavy metal pollution defend seed germination against heat stress? Effect of heavy metals (Cu(2+), Cd(2+) and Hg(2+)) on maize seed germination under high temperature.

    Science.gov (United States)

    Deng, Benliang; Yang, Kejun; Zhang, Yifei; Li, Zuotong

    2016-09-01

    Heavy metal pollution, as well as greenhouse effect, has become a serious threat today. Both heavy metal and heat stresses can arrest seed germination. What response can be expected for seed germination under both stress conditions? Here, the effects of heavy metals (Cu(2+), Cd(2+) and Hg(2+)) on maize seed germination were investigated at 20 °C and 40 °C. Compared with 20 °C, heat stress induced thermodormancy. However, this thermodormancy could be significantly alleviated by the addition of a low concentration of heavy metals. Heavy metals, as well as heat stress induced H2O2 accumulation in germinating seeds. Interestingly, this low concentration of heavy metal that promoted seed germination could be partly blocked by DMTU (a specific ROS scavenger), irrespective of temperature. Accordingly, H2O2 addition reinforced this promoting effect on seed germination, which was induced by a low concentration of heavy metal. Furthermore, we found that the NADPH oxidase derived ROS was required for seed germination promoted by the heavy metals. Subsequently, treatment of seeds with fluridone (a specific inhibitor of ABA) or ABA significantly alleviated or aggravated thermodormancy, respectively. However, this alleviation or aggravation could be partly attenuated by a low concentration of heavy metals. In addition, germination that was inhibited by high concentrations of heavy metals was also partly reversed by fluridone. The obtained results support the idea that heavy metal-mediated ROS and hormone interaction can finally affect the thermodormancy release or not.

  15. $^{204m}$Pb: A new Probe for TDPAC Experiments in Biology Complementing the Well Established Probes $^{111}$Cd and $^{199m}$Hg

    CERN Multimedia

    2002-01-01

    The short-lived nuclear probes $\\,^{111m}$Cd( t$_{1/2}$ = 49 min) , $^{199m}$Hg ( t$_{1/2}$ = 43 min) , and $^{204m}$Pb( t$_{1/2}$ = 43 min) supplied by ISOLDE are used to study the interaction of metals with biological macromolecules like, e.g., DNA and proteins. The structure and dynamics of metal sites in biomolecules are important in determining the functional efficiency of these macromolecules. Many life processes are based on such interactions. In order to study those metal sites close to physiological conditions a highly sensitive spectroscopic method is required, like Time Differential Perturbed Angular Correlation (TDPAC). Here, a radioactive atom is placed at the site of interest and by correlating the emitted $\\gamma$-quanta in space and on a nanosecond time scale local structural information is provided via the Nuclear Quadrupole Interaction. These investigations will allow a deeper insight into the adaptivity and rigidity of metal sites in the blue copper proteins (electron transfer proteins), th...

  16. 六元扩展卟啉的Zn2+,Cd2+,Hg2+单金属配合物的光电性质的理论研究%Theoretical investingation on electronic transition of [26]hexaphyrin (1.1.1.1.1.1) and their Zn2+ ,Cd2+and Hg2+ mono-metal complexes

    Institute of Scientific and Technical Information of China (English)

    高影; 韩育志; 赵利维; 林美玉; 孙刚

    2012-01-01

    The electronic absorption spectra of Zn2+,Cd2+ and Hg2+ mono-metal complexes of [26] hexaphyrind. 1.1.1.1.1) were systematically investigated using the localized density matrix (LDM) method and time-dependent density functional theory (TD-DFT). The results show that complexes are more co-planarity when HP coordinates with Zn2+ ,Cd2+ and Hg2+ ions. The absorption characteristics represent weak Q-like bands. In addition , the introduction of group 12 transition metals ( E ) leads to red shifts by adding central metal atomic number. The absorption characteristics of strong B-like bands exhibit ligand-to-metal charge transfer characteristics due to contributions from phenyl rings in the meso-carbons. The LDM method is a reliable approach for determining the electronic transition properties of the complexes and substantially reduces the computational cost.%通过定域密度矩阵方法和含时密度泛函方法研究了六元扩展卟啉及其Zn,Cd和Hg单金属配合物的光电性质.通过计算得到扩展卟啉HP同金属Zn2+,Cd2+和Hg2+发生配位时,分子趋于平面化.配合物在Q带有弱得吸收峰,它们随着中心金属的原子序数的增加产生了红移.在B带有强吸收峰,其特征峰主要来自于中心金属离子的d轨道和同金属配位的C原子所处的吡咯环以及吡咯环两侧的meso-C原子上的苯基的参与.对于扩展卟啉极其配合物,定域密度矩阵方法也可以很好的预测光谱和电子跃迁性质.

  17. Comparison of pollutant emission control strategies for cadmium and mercury in urban water systems using substance flow analysis

    DEFF Research Database (Denmark)

    Revitt, D. M.; Lundy, L.; Eriksson, Eva

    2013-01-01

    for the evaluation of ECS using substance flow analysis (SFA). The results indicate that the full implementation of existing EU legislation is capable of reducing the total emissions of cadmium (Cd) and mercury (Hg) by between 11% and 20%. The ability to apply voluntary reduction practices is shown...... increases in stormwater sediment loadings (2.6–14.9 kg/year or 0.6–2.4 kg/year for Hg) or wastewater sludge loadings (45.8–57.2 kg/year or 42.0–57.4 kg/year for Cd)....

  18. Temperature Dependences of the Product of the Differential Resistance by the Area in MIS-Structures Based on Cd x Hg1- x Te Grown by Molecularbeam Epitaxy on Alternative Si and GaAs Substrates

    Science.gov (United States)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.; Varavin, V. S.; Vasil'ev, V. V.; Dvoretskii, S. A.; Mikhailov, N. N.; Yakushev, M. V.; Sidorov, G. Yu.

    2017-06-01

    In a temperature range of 9-200 K, temperature dependences of the differential resistance of space-charge region in the strong inversion mode are experimentally studied for MIS structures based on CdxHg1-xTe (x = 0.22-0.40) grown by molecular-beam epitaxy. The effect of various parameters of structures: the working layer composition, the type of a substrate, the type of insulator coating, and the presence of a near-surface graded-gap layer on the value of the product of differential resistance by the area is studied. It is shown that the values of the product RSCRA for MIS structures based on n-CdHgTe grown on a Si(013) substrate are smaller than those for structures based on the material grown on a GaAs(013) substrate. The values of the product RSCRA for MIS structures based on p-CdHgTe grown on a Si(013) substrate are comparable with the value of the analogous parameter for MIS structures based on p-CdHgTe grown on a GaAs(013) substrate.

  19. Surface enhanced Raman scattering, natural bond orbitals and Mulliken atomic charge distribution in the normal modes of diethyldithiocarbamate cadmium (II) complex, [Cd(DDTC)2

    Science.gov (United States)

    Téllez Soto, C. A.; Costa, A. C.; Versiane, O.; Lemma, T.; Machado, N. C. F.; Mondragón, M. A.; Martin, A. A.

    2015-07-01

    Theoretical and experimental bands have been assigned to the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethyldithiocarbamate)Cd(II) complex, abbreviated as ([Cd(DDTC)2]). The calculations and spectral interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis to assist in the assignment of observed fundamentals. This study validated the unusual pseudo tetrahedral molecular structure formed around the Cd(II) cation. Surface-enhanced Raman scattering (SERS) was used to determine the interactions of the normal-modes of the diethyldithiocarbamate cadmium (II) complex on nano-structured silver surfaces. Natural bond orbital (NBO) analysis was also carried out to study the Cd(II) hybridization causing the pseudo tetrahedral geometry of the framework of the [Cd(DDTC)2] complex, and to confirm the charge transfer mechanisms through second order perturbation theory analysis of the Fox Matrix. In order to find out the electronic dispersion of the Mulliken atomic charges (MAC) in the normal modes, we calculated the MAC for each normal mode and correlated these values with the SERS effect. Experimental UV-Vis spectra were obtained and charge transfer bands were assigned. Good agreement between the calculated and experimental values for the vibrational and UV-Vis spectra was obtained.

  20. Toxicity of cadmium to soil microbial biomass and its activity: Effect of incubation time on Cd ecological dose in a paddy soil

    Institute of Scientific and Technical Information of China (English)

    LIAO Min; LUO Yun-kuo; ZHAO Xiao-min; Huang Chang-yong

    2005-01-01

    Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity,including microbial biomass carbon (Cmic), dehydrogenase activity (DHA) and basal respiration (BR), etc., Cmic, DHA, BR were used as bioindicators of the toxic effect of Cd in soil. This study was conducted to determine the effects of Cd on soil microbial biomass and its activity in a paddy soil. The inhibition of microbial biomass and its activity by different Cd concentrations was described by the kinetic model (M1) and the sigmoid dose-response model (M2) in order to calculate three ecological doses of Cd:ED50, ED10 and ED5. Results showed that M2 was better fit than M1 for describing the ecological toxicity dose effect of cadmium on soil microbial biomass and its activity in a paddy soil. M2 for ED values (mg/kg soil) of Cmic, DHA, BR best fitted the measured paddy soil bioindicators. M2 showed that all ED values (mg/kg) increased in turn with increased incubation time. ED50, ED10 and ED5 of Cmic with M2 were increased in turn from 403.2, 141.1,100.4 to 1000.7, 230.9, 144.8, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of DHA with M2 increased in turn from 67.6, 6.2, 1.5 to 101.1, 50.9, 41.0, respectively, after 10 d to 60 d of incubation. ED50, ED10 and ED5 of BR with M2 increased in turn from 149.7, 6.5, 1.8 to 156.5, 50.8, 35.5, respectively,after 10 d to 60 d of incubation. So the ecological dose increased in turn with increased incubation time for M2 showed that toxicity of cadmium to soil microbial biomass and its activity was decreased with increased incubation time.

  1. Al-Cd Alloy Formation by Aluminum Underpotential Deposition from AlCl3+NaCl Melts on Cadmium Substrate

    Science.gov (United States)

    Jovićević, Niko; Cvetković, Vesna S.; Kamberović, Željko J.; Jovićević, Jovan N.

    2013-02-01

    Aluminum was incorporated into a polycrystalline cadmium electrode surface by underpotential deposition from equimolar AlCl3+ NaCl melt at 473 K, 523 K, and 573 K (200 °C, 250 °C, and 300 °C). The process was studied by linear sweep voltammetry and potentiostatic deposition/galvanostatic striping. The deposits were characterized X-ray diffraction (XRD), Auger electron spectroscopy (AES), and electron probe microanalyzer (EPMA). The electrochemical measurements showed evidence of Cd-Al alloys being formed but they could not be identified. The growth kinetics of the Cd-Al layers of various proportion and depths that depended on temperature and deposition time were described.

  2. Confirmation of Auger-1 Minority-Carrier Lifetimes in Hg0.77Cd0.23Te and Prediction of Dark Current for Long-Wave Infrared Focal-Plane Arrays

    Science.gov (United States)

    Destefanis, V.; Kerlain, A.

    2016-09-01

    Minority-carrier lifetime measurements have been carried out on Hg0.77Cd0.23Te (111)B materials with gap suitable for detection in the Long-Wave Infrared (LWIR) band. The materials were grown on top of CdZnTe substrates using a liquid-phase epitaxy (LPE) process. From measurements done at 80 K, a clear difference in terms of minority-carrier lifetimes was obtained, as expected, between p-intrinsic (≤5 ns) and n-extrinsic doped samples (420 ns). Minority-carrier lifetimes were also measured as a function of temperature for the n-type samples. Auger-1-limited lifetimes were demonstrated over a wide temperature range (from 80 K to 300 K) with negligible Radiative or Shockley-Read-Hall lifetime contributions. Predictions of dark current densities are made from those lifetime measurements, assuming an Auger-1-limited lifetime. The agreement is very good between the predictions and dark current densities measured from p-on- n 640 × 512 pixels LWIR HgCdTe focal-plane arrays with 15- μm pitch from SOFRADIR, Agreement between predicted and measured dark currents and Rule'07 for LWIR is also demonstrated herein. Finally, minority-carrier lifetime measurements are demonstrated as a predictive method for focal-plane array performance. State-of-the-art dark currents from SOFRADIR p-on- n LWIR focal-plane arrays based upon high-quality HgCdTe materials are also illustrated.

  3. The cadmium-tolerant pea (Pisum sativum L.) mutant SGECdt is more sensitive to mercury: assessing plant water relations.

    Science.gov (United States)

    Belimov, Andrey A; Dodd, Ian C; Safronova, Vera I; Malkov, Nikita V; Davies, William J; Tikhonovich, Igor A

    2015-04-01

    Heavy metals have multiple effects on plant growth and physiology, including perturbation of plant water status. These effects were assessed by exposing the unique Cd-tolerant and Cd-accumulating pea (Pisum sativum L.) mutant SGECd(t) and its wild-type (WT) line SGE to either cadmium (1, 4 μM CdCl2) or mercury (0.5, 1, 2 μM HgCl2) in hydroponic culture for 12 days. When exposed to Cd, SGECd(t) accumulated more Cd in roots, xylem sap, and shoot, and had considerably more biomass than WT plants. WT plants lost circa 0.2 MPa turgor when grown in 4 μM CdCl2, despite massive decreases in whole-plant transpiration rate and stomatal conductance. In contrast, root Hg accumulation was similar in both genotypes, but WT plants accumulated more Hg in leaves and had a higher stomatal conductance, and root and shoot biomass compared with SGECd(t). Shoot excision resulted in greater root-pressure induced xylem exudation of SGECd(t) in the absence of Cd or Hg and following Cd exposure, whereas the opposite response or no genotypic differences occurred following Hg exposure. Exposing plants that had not been treated with metal to 50 μM CdCl2 for 1h increased root xylem exudation of WT, whereas 50 μM HgCl2 inhibited and eliminated genotypic differences in root xylem exudation, suggesting differences between WT and SGECd(t) plants in aquaporin function. Thus, root water transport might be involved in mechanisms of increased tolerance and accumulation of Cd in the SGECd(t) mutant. However, the lack of cross-tolerance to Cd and Hg stress in the mutant indicates metal-specific mechanisms related to plant adaptation.

  4. Growth, crystal structure and optical properties of layered dibarium cadmium diborate, Ba{sub 2}Cd(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Min [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Pan Shilie, E-mail: slpan@ms.xjb.ac.cn [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Han Jian [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Yang Yun; Cui Liang [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou Zhongxiang [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China)

    2011-06-09

    Graphical abstract: A new phase, Ba{sub 2}Cd(BO{sub 3}){sub 2}, has been discovered in the ternary M{sub 2}O-CdO-B{sub 2}O{sub 3} (M = alkaline-earth metal) system. The crystal structure is built up from the stacking of infinite stoichiometric layers along the c axis. Display Omitted Highlights: > Ba{sub 2}Cd(BO{sub 3}){sub 2} is the first borate discovered in the ternary M{sub 2}O-CdO-B{sub 2}O{sub 3} (M = alkaline-earth metal) system. > Ba{sub 2}Cd(BO{sub 3}){sub 2} crystal structure includes a two-dimensional infinite stoichiometric layers. > Intrinsic layered structure leads to layered crystal morphology in the process of crystal growth. - Abstract: A novel dibarium cadmium diborate, Ba{sub 2}Cd(BO{sub 3}){sub 2}, has been successfully synthesized by standard solid-state reaction. Large sheet-like crystal with size up to 20 mm x 15 mm x 0.7 mm has been obtained using top-seed solution growth method. Ba{sub 2}Cd(BO{sub 3}){sub 2} crystallizes in the monoclinic space group C2/m with a = 9.6305(4) A, b = 5.3626(3) A, c = 6.5236(2) A, {beta} = 118.079(3){sup o}, Z = 2. The crystal structure is composed of isolated [BO{sub 3}] triangles, [CdO{sub 6}] octahedra and [BaO{sub 9}] polyhedra. CdO{sub 6} are vertex-connected with six BO{sub 3} to form infinite {sub {infinity}}[Cd(BO{sub 3}){sub 2}] layers extending in (0 0 1) plane, and two rows of Ba atoms closely occupy two side of {sub {infinity}}[Cd(BO{sub 3}){sub 2}] layers to forming stoichiometric sheets. IR and transmittance spectrum of Ba{sub 2}Cd(BO{sub 3}){sub 2} were reported.

  5. Cadmium and mercury accumulation in European hare (Lepus europaeus): age-dependent relationships in renal and hepatic tissue.

    Science.gov (United States)

    Petrović, Zoran; Teodorović, Vlado; Djurić, Spomenka; Milićević, Dragan; Vranić, Danijela; Lukić, Mirjana

    2014-12-01

    A total of 63 European hares have been collected from five Serbian agricultural regions. The hares assayed were divided into four age groups (3-6 months, 12 months, 12-24 months, and 24-36 months) and investigated upon presence at cadmium (Cd) and mercury (Hg) in the kidney and liver. The positive significant correlation (Ps-Pearson's coefficient) between Cd concentrations in the kidney and liver within age group the 3-6 months was found (Ps = 0.81, p 0.05). Statistically significant differences were registered between Hg content in the liver of the hares aged 24-36 and 12 months (p 0.05). The strong statistically significant associations were registered between Cd and Hg content in the liver (Cd L/Hg L) in the age group 3-6 and 12-24 months (Cd L/Hg L, Ps = 0.94; p < 0.001 and Ps = 0.91; p < 0.001, respectively). The polynomial regression model used for graphing the observed data seems to be a method for modeling the relationship between measured Cd and Hg concentrations in the liver and kidney as first approximation for bioaccumulation in hares.

  6. DNA damage and transcriptional changes in the gills of mytilus galloprovincialis exposed to nanomolar doses of combined metal salts (Cd, Cu, Hg.

    Directory of Open Access Journals (Sweden)

    Laura Varotto

    Full Text Available Aiming at an integrated and mechanistic view of the early biological effects of selected metals in the marine sentinel organism Mytilus galloprovincialis, we exposed mussels for 48 hours to 50, 100 and 200 nM solutions of equimolar Cd, Cu and Hg salts and measured cytological and molecular biomarkers in parallel. Focusing on the mussel gills, first target of toxic water contaminants and actively proliferating tissue, we detected significant dose-related increases of cells with micronuclei and other nuclear abnormalities in the treated mussels, with differences in the bioconcentration of the three metals determined in the mussel flesh by atomic absorption spectrometry. Gene expression profiles, determined in the same individual gills in parallel, revealed some transcriptional changes at the 50 nM dose, and substantial increases of differentially expressed genes at the 100 and 200 nM doses, with roughly similar amounts of up- and down-regulated genes. The functional annotation of gill transcripts with consistent expression trends and significantly altered at least in one dose point disclosed the complexity of the induced cell response. The most evident transcriptional changes concerned protein synthesis and turnover, ion homeostasis, cell cycle regulation and apoptosis, and intracellular trafficking (transcript sequences denoting heat shock proteins, metal binding thioneins, sequestosome 1 and proteasome subunits, and GADD45 exemplify up-regulated genes while transcript sequences denoting actin, tubulins and the apoptosis inhibitor 1 exemplify down-regulated genes. Overall, nanomolar doses of co-occurring free metal ions have induced significant structural and functional changes in the mussel gills: the intensity of response to the stimulus measured in laboratory supports the additional validation of molecular markers of metal exposure to be used in Mussel Watch programs.

  7. A new ROIC with high-voltage protection circuit of HgCdTe e-APD FPA for passive and active imaging

    Science.gov (United States)

    Chen, Guoqiang; Zhang, Junling; Wang, Pan; Zhou, Jie; Gao, Lei; Ding, Ruijun

    2012-12-01

    HgCdTe electrons initiated avalanche photodiodes (e-APDs) in linear multiplication mode can be used for high speed applications such as active imaging. A readout integrated circuit of e-APD FPA is designed for dual mode passive/active imaging system. Unit cell circuit architecture of ROIC includes a high voltage protection module, a Sample-Hold circuit module, a comparator, output driver stage and a integrator module which includes a amplifier and three capacitors. Generally, APD FPA works at reversed bias such as 5V-15V in active imaging mode, and pixels' dark currents increase exponentially as the reverse-bias voltage is increased. Some cells of ROIC may be short to high voltage because of avalanche breakdown of diodes. If there is no protection circuit, the whole ROIC would be burnt out. Thus a protection circuit module introduced in every ROIC cell circuit is necessary to make sure the rest units of ROIC can still work. Conventional 5V CMOS process is applied to implement the high voltage protection with the small area other than LDMOS in high voltage BCD process in the limited 100μm×100μm pitch area. In integrator module, three integration capacitors are included in the ROIC to provide switchable well capacity. One of them can be shared in two modes in order to save area. Constraints such as pixel area and power lead us design toward a simple one-stage cascade operational transconductance amplifier (OTA) as pre-amplifier which can avoid potential instability caused by inaccuracy of MOSFET Model at 77K.

  8. Variation of Cd concentration in various rice cultivars and derivation of cadmium toxicity thresholds for paddy soil by species-sensitivity distribution

    Institute of Scientific and Technical Information of China (English)

    SONG Wen-en; CHEN Shi-bao; LIU Ji-fang; CHEN Li; SONG Ning-ning; LI Ning; LIU Bin

    2015-01-01

    It is imperative to derive an appropriate cadmium (Cd) health risk toxicity threshold for paddy soils to ensure the Cd con-centration of rice grains meet the food safety standard. In this study, 20 rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0 (CK), 0.3 mg kg–1 (T1) and 0.6 mg kg–1 (T2) Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed signiifcant difference (P<0.05) in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143–0.202, 0.128–0.458 and 0.332–0.806 mg kg–1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain (BCFs) and transfer factors (TFs, root to grain and straw to grain) among the tested cultivars were observed in this study. The bioconcentration factors (BCFgrain) and TFs of the 20 rice cultivars were 0.300–1.112 and 0.342–0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with signiifcant differences among these 20 rice cultivars. The bioconcentration factors (BCFgrain) and TFs among the 20 rice cultivars ranged from 0.300–1.112 and 0.342–0.817, respectively. The species-sensitivity distribu-tion (SSD) of Cd sensitivity of the rice species could be iftted wel with Burr-III (R2=0.987) based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg–1 in the present study.

  9. Recovery of zinc and cadmium from spent batteries using Cyphos IL 102 via solvent extraction route and synthesis of Zn and Cd oxide nanoparticles.

    Science.gov (United States)

    Singh, Rashmi; Mahandra, Harshit; Gupta, Bina

    2017-09-01

    The overall aim of this study is to separate and recover zinc and cadmium from spent batteries. For this purpose Cyphos IL 102 diluted in toluene was employed for the extraction and recovery of Zn and Cd from Zn-C and Ni-Cd batteries leach liquor. The influence of extractant concentration for the leach liquors of Zn-C (0.01-0.05mol/L) and Ni-Cd (0.04-0.20mol/L) batteries has been investigated. Composition of the leach liquor obtained from Zn-C/Ni-Cd spent batteries is Zn - 2.18g/L, Mn - 4.59g/L, Fe - 4.0×10(-3)g/L, Ni - 0.2×10(-3)g/L/Cd - 4.28g/L, Ni - 0.896×10(-1)g/L, Fe - 0.148g/L, Co - 3.77×10(-3)g/L, respectively. Two stage counter current extraction at A/O 1:1 and 3:2 with 0.04mol/L and 0.2mol/L Cyphos IL 102 for Zn and Cd, respectively provide more than 99.0% extraction of both the metal ions with almost negligible extraction of associated metal ions. A stripping efficiency of around 99.0% for Zn and Cd was obtained at O/A 1:1 using 1.0mol/L HNO3 in two and three counter current stages, respectively. ZnO and CdO were also synthesized using the loaded organic phase and characterized using XRD, FE-SEM and EDX techniques. XRD peaks of ZnO and CdO correspond to zincite and monteponite, respectively. The average particle size was ∼27.0nm and ∼37.0nm for ZnO and CdO, respectively. The EDX analysis of ZnO and CdO shows almost 1:1 atomic percentage. Copyright © 2017. Published by Elsevier Ltd.

  10. A study on dependence of the structural, optical and electrical properties of cadmium lead sulphide thin films on Cd/Pb ratio

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Sinitha B., E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Abraham, Anitha, E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Philip, Rachel Reena, E-mail: reenatara@rediffmail.com [Thin film research Lab, U.C. College, Aluva, Kerala (India); Pradeep, B., E-mail: bp@cusat.ac.in [Solid State Physics Laboratory, Cochin University of science and Technology, Cochin (India); Shripathi, T., E-mail: shri@csr.res.in, E-mail: vganesancsr@gmail.com; Ganesan, V., E-mail: shri@csr.res.in, E-mail: vganesancsr@gmail.com [UGC-DAE CSR, Khandwa Road, Indore, 452001, Madhya Pradesh (India)

    2014-10-15

    Cadmium Lead Sulphide thin films with systematic variation in Cd/Pb ratio are prepared at 333K by CBD, adjusting the reagent-molarity, deposition time and pH. XRD exhibits crystalline-amorphous transition as Cd% exceeds Pb%. AFM shows agglomeration of crystallites of size ∼50±5 nm. EDAX assess the composition whereas XPS ascertains the ternary formation, with binding energies of Pb4f{sub 7/2} and 4f{sub 5/2}, Cd3d{sub 5/2} and 3d{sub 3/2} and S2p at 137.03, 141.606, 404.667, 412.133 and 160.218 eV respectively. The optical absorption spectra reveal the variance in the direct allowed band gaps, from 1.57eV to 2.42 eV as Cd/Pb ratio increases from 0.2 to 2.7, suggesting possibility of band gap engineering in the n-type films.

  11. The high-pressure cadmium borate Cd{sub 6}B{sub 22}O{sub 39} . H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Sohr, Gerhard; Ciaghi, Nina; Wurst, Klaus; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2015-06-01

    Single crystals of the hydrous cadmium borate Cd{sub 6}B{sub 22}O{sub 39} . H{sub 2}O were obtained through a high-pressure/high-temperature experiment at 4.7 GPa and 1000 C using a Walker-type multianvil apparatus. CdO and partially hydrolyzed B{sub 2}O{sub 3} were used as starting materials. A single crystal X-ray diffraction study has revealed that the structure of Cd{sub 6}B{sub 22}O{sub 39} . H{sub 2}O is similar to that of the type M{sub 6}B{sub 22}O{sub 39} . H{sub 2}O (M=Fe, Co). Layers of corner-sharing BO{sub 4} groups are interconnected by BO{sub 3} groups to form channels containing the metal cations, which are six- and eight-fold coordinated by oxygen atoms. The compound crystallizes in the space group Pnma (no. 62) [R1=0.0379, wR2=0.0552 (all data)] with the unit cell dimensions a=1837.79(5), b=777.92(2), c=819.08(3) pm, and V=1171.00(6) Aa{sup 3}. The IR and Raman spectra reflect the structural characteristics of Cd{sub 6}B{sub 22}O{sub 39} . H{sub 2}O.

  12. M@B9 and M@B10 molecular wheels containing planar nona-and deca-coordinate heavy group 11, 12, and 13 metals (M=Ag, Au, Cd, Hg, In, Tl)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A density functional and ab initio theory investigation on M@B9 and M@B10 molecular wheels containing planar nona-and deca-coordinate heavy group 11, 12 and 13 metals (M=Ag, Au, Cd, Hg, In, Ti) has been performed. These unusual clusters all prove to be true minima on the potential energy surfaces of the systems and σ+π double aromatic in nature. The first two vertical one-electron detachment energies of M@B-10 (M=Ag, Au) anions and first two ionization potentials of M@B9 (M=Ag, Au) and M@B10 (M=Cd, Hg) neutrals were calculated to aid future experiments. The cluster complexes designed in this work may expend the domain of planar hyper-coordinate elements to include heavy group 11, 12, and 13 metals and serve as interesting candidates to be targeted in experiments.

  13. Cadmium - is it hazardous

    Energy Technology Data Exchange (ETDEWEB)

    Zartner-Nyilas, G.; Valentin, H.; Schaller, K.H.; Schiele, R.

    1983-01-01

    The report summarizes the state of knowledge and experience on cadmium. Biological, toxicological and epidemiological data have been evaluated. Cd pollution of the environment is reviewed under the aspect of human health. Uptake in food, threshod values of Cd exposure of the population, types and extent of health hazards, possible carcinogenic effects and future fields of research are discussed.

  14. Interaction of selenium with cadmium and mercury in semen and reproductive tissues: in vivo and in vitro studies

    Energy Technology Data Exchange (ETDEWEB)

    Alabi, N.S.

    1984-01-01

    Studies were conducted to investigate the metabolism of selenium (Se), and the influences of Se on the metabolism of cadmium (Cd) and inorganic mercury (Hg) in rats, and in ram semen in vitro. Se-deficient (-Se) or Se-adequate (+Se) rats were injected intraperitoneally with either /sup 109/CdCl/sub 2/ or /sup 203/HgNO/sub 3/. Semen ejaculates from yearling Suffolk rams were used for the in vitro studies. Whole-body retention of Cd and Hg in rats was significantly increased by Se. However, regardless of the Se status, the predominant route of Cd and Hg excretion was feces. Data on whole tissue Cd retention for both -Se and +Se rats gave the following order of decreasing tissue Cd levels: liver > kidney > testis > epididymis > seminal vesicles > prostate > brain. Cd and Hg concentrations ranging from 10/sup -6/ to 10/sup -2/ M were shown to be injurious to ram sperm in vitro as indicated by the depressed motility and reduced oxygen uptake.

  15. Temperature and Field Dependences of Parameters of the Equivalent Circuit Elements of MIS Structures Based on MBE n-Hg0.775Cd0.225Te in the Strong Inversion Mode

    Science.gov (United States)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.

    2016-11-01

    A technique is proposed for the determining the parameters of the equivalent circuit elements in strong inversion mode using the measurement results of the admittance of MIS structures based on n-Hg0.775Cd0.225Te grown by molecular beam epitaxy. It is shown that at 77 K and frequencies above 10 kHz, the capacitancevoltage characteristics of MIS structures based on n-Hg0.775Cd0.225Te with a near-surface graded gap layer have a high-frequency behavior with respect to the recharge time of surface states located near the Fermi level of intrinsic semiconductor. It is established that the electron concentration in the near-surface graded-gap layer exceeds an average concentration found by the Hall method by more than 2 times. The proposed technique was used for determining the temperature dependences of the insulator capacitance, capacitance and differential resistance of the space-charge region, and capacitance of the inversion layer in MIS structures based on n-Hg0.775Cd0.225Te without a graded-gap layer. The temperature and voltage dependences of the parameters of the equivalent circuit elements in strong inversion are calculated. The results of calculation are qualitatively consistent with the results obtained from the measurements of the admittance.

  16. Zirconia-coated graphite adsorption bar micro-extraction combined with ETV-ICP-MS for the determination of trace amounts of Cd, Hg and Pb in environmental and biological samples.

    Science.gov (United States)

    Pu, Xuli; Jiang, Zucheng; Hu, Bin

    2006-07-01

    In this work, a new and simple micro-extraction method termed graphite adsorption bar micro-extraction was developed, for the first time, for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) determination of trace Cd, Hg and Pb. In this method, the graphite bar was first coated with zirconia and then inserted into the sample solution for extraction. The graphite bar enriched with the analytes was inserted directly into a graphite tube, and subsequently analyzed by ETV-ICP-MS according to an established temperature program. The experimental parameters, which had influence on the extraction and vaporization, were systematically investigated and the optimal experimental conditions were established. Under the optimized conditions, the detection limits of the method were 0.05, 0.42 and 0.06 pg/ml for Cd, Hg and Pb and the relative standard deviations (RSDs) for 11 replicates at the 0.1 ng/ml level were 7.4, 8.2 and 7.7%, respectively. The proposed method was successfully applied to the determination of trace Cd, Hg and Pb in environmental and biological samples. The results of the experiments indicate that the method has a high enrichment factor and sample utilization efficiency. Furthermore, the method is fast and environment-friendly.

  17. Variation of Cd concentration in various rice cultivars and derivation of cadmium toxicity thresholds for paddy soil by species-sensitivity distribution

    Institute of Scientific and Technical Information of China (English)

    SONG Wen-en[1; CHEN Shi-bao[1; LIU Ji-fang[2; CHEN Li[3; SONG Ning-ning[1; LINing[1; LIU Bin[1

    2015-01-01

    It is imperative to derive an appropriate cadmium (Cd) health risk toxicity threshold for paddy soils to ensure the Cd con- centration of rice grains meet the food safety standard. In this study, 20 rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0 (CK), 0.3 mg kg-1 (T1) and 0.6 mg kg-1(T2) Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed significant difference (P〈0.05) in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143-0.202, 0.128-0.458 and 0.332-0.806 mg kg-1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain (BCFs) and transfer factors (TFs, root to grain and straw to grain) among the tested cultivars were observed in this study. The bioconcentration factors (BCFgrain) and TFs of the 20 rice cultivars were 0.300-1.112 and 0.342-0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with significant differences among these 20 rice cultivars. The bioconcentration factors (BCFgrain) and TFs among the 20 rice cultivars ranged from 0.300-1.112 and 0.342-0.817, respectively. The species-sensitivity distribu- tion (SSD) of Cd sensitivity of the rice species could be fitted well with Burr-Ill (R2=0.987) based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg-1 in the present study.

  18. Cadmium, mercury, and lead in kidney cortex of living kidney donors: Impact of different exposure sources,

    Energy Technology Data Exchange (ETDEWEB)

    Barregard, Lars, E-mail: lars.barregard@amm.gu.se [Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and University of Gothenburg, P.O. Box 414, SE 405 30 Gothenburg (Sweden); Fabricius-Lagging, Elisabeth [Department of Nephrology, Sahlgrenska University Hospital and Boras Hospital (Sweden); Lundh, Thomas [Department of Occupational and Environmental Medicine, Lund University Hospital and Lund University (Sweden); Moelne, Johan [Department of Clinical Pathology, Sahlgrenska University Hospital and University of Gothenburg (Sweden); Wallin, Maria [Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and University of Gothenburg, P.O. Box 414, SE 405 30 Gothenburg (Sweden); Olausson, Michael [Department of Transplantation and Liver Surgery, Sahlgrenska University Hospital and University of Gothenburg (Sweden); Modigh, Cecilia; Sallsten, Gerd [Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and University of Gothenburg, P.O. Box 414, SE 405 30 Gothenburg (Sweden)

    2010-01-15

    Background: Most current knowledge on kidney concentrations of nephrotoxic metals like cadmium (Cd), mercury (Hg), or lead (Pb) comes from autopsy studies. Assessment of metal concentrations in kidney biopsies from living subjects can be combined with information about exposure sources like smoking, diet, and occupation supplied by the biopsied subjects themselves. Objectives: To determine kidney concentrations of Cd, Hg, and Pb in living kidney donors, and assess associations with common exposure sources and background factors. Methods: Metal concentrations were determined in 109 living kidney donors aged 24-70 years (median 51), using inductively coupled plasma-mass spectrometry (Cd and Pb) and cold vapor atomic fluorescence spectrometry (Hg). Smoking habits, occupation, dental amalgam, fish consumption, and iron stores were evaluated. Results: The median kidney concentrations were 12.9 {mu}g/g (wet weight) for cadmium, 0.21 {mu}g/g for mercury, and 0.08 {mu}g/g for lead. Kidney Cd increased by 3.9 {mu}g/g for a 10 year increase in age, and by 3.7 {mu}g/g for an extra 10 pack-years of smoking. Levels in non-smokers were similar to those found in the 1970s. Low iron stores (low serum ferritin) in women increased kidney Cd by 4.5 {mu}g/g. Kidney Hg increased by 6% for every additional amalgam surface, but was not associated with fish consumption. Lead was unaffected by the background factors surveyed. Conclusions: In Sweden, kidney Cd levels have decreased due to less smoking, while the impact of diet seems unchanged. Dental amalgam is the main determinant of kidney Hg. Kidney Pb levels are very low due to decreased exposure.

  19. Assessment of micro, macro, toxic elements (Cd, Hg, Pb) and fatty acids profile in consumed fish commercially available in Cananeia and Cubatao, Sao Paulo State; Avaliacao de micro e macroelementos, elementos toxicos (Cd, Hg e Pb) e acidos graxos, em peixes disponiveis comercialmente para consumo em Cananeia e Cubatao, Estado de Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Curcho, Michel Rodrigues da Silva Morales

    2009-07-01

    Aside from their nutritional importance, fish are considered one of the most important bio indicators in aquatic systems for the estimation of pollution levels by toxic metals. This is so, since fish can bio accumulate these elements and they occupy different trophic levels and present different sizes and age. The purpose of the present study was to contribute with important data for the knowledge of nutritional and toxic constituents in muscles of the most consumed fish species from two coastal regions, Cananeia and Cubatao. Cananeia fish species analyzed were: Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Centropomus undecimalis (Robalo peba) and Mugil platanus (Tainha). From Cubatao, Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Menticirrhus americanus (Perna de moca), Sardella braziliensis (Sardinha) and Mugil liza (Tainha). For this study, analytical methodologies were developed and validated, regarding precision and accuracy, by means of certified reference materials. Micronutrients (Ca, Fe, K, Na, Se and Zn) and some trace elements (As, Br, Co, Cr, Rb) in fish muscle were determined by means of neutron activation analysis (NAA). Cold Vapor Atomic Absorption Spectrometry (CV AAS) was used for total Hg determination and Electrothermal Atomic Absorption Spectrometry (ET AAS) for Cd and Pb determinations. Proximate composition determinations according to AOAC methodologies and fatty acids profiles by gas chromatography were done in these muscle fish samples. Regarding fatty acids profile from the {omega}-6 family, Tainha species pool presented the highest values (8.9%) and Pescada species pool the lowest ones (4.4%) for Cananeia species. Fatty acids from the {omega}-3 family, Sardinha pool species presented the highest values (31.8%) for all species analyzed. Regarding micronutrients content great concentration variations between individual of the same species and between different species were observed. Discriminate analysis

  20. CADMIUM – ENVIRONMENTAL HAZARD

    Directory of Open Access Journals (Sweden)

    Henryka Langauer-Lewowicka

    2010-06-01

    Full Text Available The paper presents some information about current status of cadmium as an environmental health problem. Agricultural uses of phosphate fertilizers, sewage sludge and industrial uses of Cd are the major source of widespread of this metal at trace levels into the general environment and human foodstuffs. It is well known that high cadmium (Cd exposure causes renal damage, anemia, enteropathy, osteoporosis, osteomalacia, whereas the dose-response relationship at low levels exposure is less established. During the last decade an increasing number of studies have found an adverse health effects due to low environmental exposure to Cd. Many authors try to determine the relationship between Cd intake and Cd toxicity indicators, especially dealing renal tubular damage. The level of b2-microglobulin in urine is regarded as the most sensitive biomarker of renal disfunction due to low environmental Cd concentrations.

  1. Cadmium, iron, lead and mercury bioaccumulation in abu mullet, Liza abu, different tissues from Karoun and Karkheh rivers, Khozestan, Iran.

    Science.gov (United States)

    Askary Sary, Abolfazl; Beheshti, Mahboubeh

    2012-02-01

    Lead, mercury, cadmium and iron concentration in following tissues: muscle, liver and gill of Liza abu in Karoun and Kharkheh were measured. Karoun and Kharkheh are important rivers in Iran. Significant variation in metal values were evaluated using Student's t test at p < 0.05. Result showed that maximum concentration of metals were recorded in gill tissues. Iron concentration was higher than lead, cadmium and mercury in different organs (p < 0.05). The level of metals Cd, Hg, Fe in different tissues of Karoun river was higher than Karkheh river (p < 0.05). Metals level in different tissue were upper than WHO standard.

  2. Analysis of the auger recombination rate in P+N-n-N-N HgCdTe detectors for HOT applications

    Science.gov (United States)

    Schuster, J.; Tennant, W. E.; Bellotti, E.; Wijewarnasuriya, P. S.

    2016-05-01

    Infrared (IR) photon detectors must be cryogenically cooled to provide the highest possible performance, usually to temperatures at or below ~ 150K. Such low operating temperatures (Top) impose very stringent requirements on cryogenic coolers. As such, there is a constant push in the industry to engineer new detector architectures that operate at higher temperatures, so called higher operating temperature (HOT) detectors. The ultimate goal for HOT detectors is room temperature operation. While this is not currently possibly for photon detectors, significant increases in Top are nonetheless beneficial in terms of reduced size, weight, power and cost (SWAP-C). The most common HgCdTe IR detector architecture is the P+n heterostructure photodiode (where a capital letter indicates a wide band gap relative to the active layer or "AL"). A variant of this architecture, the P+N-n-N-N heterostructure photodiode, should have a near identical photo-response to the P+n heterostructure, but with significantly lower dark diffusion current. The P+N-n-N-N heterostructure utilizes a very low doped AL, surrounded on both sides by wide-gap layers. The low doping in the AL, allows the AL to be fully depleted, which drastically reduces the Auger recombination rate in that layer. Minimizing the Auger recombination rate reduces the intrinsic dark diffusion current, thereby increasing Top. Note when we use the term "recombination rate" for photodiodes, we are actually referring to the net generation and recombination of minority carriers (and corresponding dark currents) by the Auger process. For these benefits to be realized, these devices must be intrinsically limited and well passivated. The focus of this proceeding is on studying the fundamental physics of the intrinsic dark currents in ideal P+N-n-N-N heterostructures, namely Auger recombination. Due to the complexity of these devices, specifically the presence of multiple heterojunctions, numerical device modeling techniques must be

  3. Separation of Hg(Ⅱ), Cu(Ⅱ) and Cd(Ⅱ) by Complexation-ultrafiltration with Poly(acrylic acid) Sodium%聚丙烯酸钠配合-超滤分离Hg(Ⅱ)、Cu(Ⅱ)和Cd(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    曾坚贤; 贺勤程; 孙霞辉; 郑立锋

    2010-01-01

    以聚丙烯酸钠为配合剂,研究了Hg(Ⅱ)、Cu(Ⅱ)和Cd(Ⅱ)混合溶液配合-超滤分离行为. 考察了pH值和负载比LR对混合体系分离的影响,结果表明,pH=5适宜分离;当LR从0.01增大至2时,金属离子分离系数SHg-Cd和SHg-Cu逐渐增大,LR=2时达到最大值. 在pH=5、LR=2、体积浓缩因子为15和各金属离子的初始质量浓度为30 mg/L时,截留液中金属离子的质量浓度ρr,Hg、ρr,Cu和ρr,Cd分别为435.3、42.6和34.2 mg/L;SHg-Cd、SHg-Cu和Scu-Cd基本不变,依次为229.3、184.3和1.2,即Hg(Ⅱ)得到选择性浓缩. 浓缩液的洗涤研究结果表明,随着洗涤液体积增大,ρr,Hg基本不变,ρr,Cu 和ρr,Cd分别下降至12.54和4.73 mg/L. 收集含Cu(Ⅱ)和Cd(Ⅱ)的各渗透液,调节LR=0.033和pH=5,浓缩16倍时,ρr,Cu从27.34 mg/L升高至430.9 mg/L,ρr,Cd从27.83 mg/L仅升高至61.5 mg/L,Scu-Cd为95.8,Cu(Ⅱ)获得选择性浓缩.

  4. Synthesis and Crystal Structure of Dinuclear Cadmium Complex [Cd2(phen)4(fca)2](ClO4)2·(H2O)2

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-Xiang; ZHANG Ze; WU Jie-Ying; TIAN Yu-Peng; DU Peng; LIU Qing-Liang; FUN Hoong Kun; C. Suchada

    2003-01-01

    A novel complex [Cd2(phen)4(fca)2](ClO4)2((H2O)2 (fca = dianion of 3-ferrocenyl- 2-crotonic acid, phen = 1,10-phenanthroline) has been synthesized and characterized by X-ray single-crystal structure analysis. It crystallizes in triclinic system, space group Pī with a = 11.6297(5), b = 12.5165(5), c = 13.8986(6) A, α = 63.345(1), β = 87.747(1), γ = 71.862(1)°, V = 1706.20(1) A3, Z = 1, Dc = 1.673 g/cm3, F(000) = 868 and μ(MoKα) = 1.185 mm-1 (λ = 0.71073 A). R = 0.0800 and Wr = 0.1793 for 7653 observed reflections (I > 2σ(I)). The structure consists of a dinuclear cation [Cd2(phen)4(fca)2]2+, two discrete perchlorate anions and two water molecules. The cationic part of the complex shows a tetrametallic core in which two fca groups act as the (O, O') bridging ligands between two cadmium(Ⅱ) ions with a distorted octahedral environment. The Cd…Cd intradimer distance is 4.128 A.

  5. Speciation of Dissolved Cadmium

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Andersen, Sjur; Christensen, Thomas Højlund

    1995-01-01

    Equilibrium dialysis and ion exchange methods, as well as computer calculations (GEOCHEM), were applied for speciation of dissolved cadmium (Cd) in test solutions and leachate samples. The leachate samples originated from soil, compost, landfill waste and industrial waste. The ion exchange (IE...... leachates showed different Cd speciation patterns as expected. Some leachates were dominated by free divalent Cd (1-70%), some by inorganic complexes (1-87%), and some by organic complexes (7-98%)....

  6. Synthesis of Co-Doped CdS Nanocrystals by Direct Thermolysis of Cadmium and Cobalt Thiolate Clusters

    Directory of Open Access Journals (Sweden)

    Jianing Zhao

    2015-01-01

    Full Text Available Co-doped CdS (Co:CdS nanocrystals with controllable morphology (quantum dots and nanorods were easily synthesized by direct thermolysis of (Me4N2[Co4(SC6H510] and (Me4N4[S4Cd10(SPh16] under different precursor concentration, in virtue of the ions exchange of molecular clusters. The Co:CdS quantum dots were produced under low precursor concentration, and the Co:CdS nanorods could be obtained under higher precursor concentration. The Co-doping effect on the structure, growth process, and property of CdS nanocrystals was also investigated. The results indicated that the Co-doping was favorable for the formation of the nanorod structures for a short reaction time. In addition, the Co-doping in the CdS lattice resulted in the ferromagnetic property of the Co:CdS quantum dots at room temperature. Moreover, compared with the CdS quantum dots, the Co:CdS quantum dots exhibited obvious quantum confinement effect and photoluminescence emission with slightly red-shift.

  7. Investigating a potential mechanism of Cd resistance in Chironomus riparius larvae using kinetic analysis of calcium and cadmium uptake

    Energy Technology Data Exchange (ETDEWEB)

    Gillis, Patricia L. [Department of Biology, McMaster University, Hamilton, ON, L8S-4K1 (Canada)], E-mail: patty.gillis@ec.gc.ca; Wood, Chris M. [Department of Biology, McMaster University, Hamilton, ON, L8S-4K1 (Canada)

    2008-09-17

    The uptake kinetics of waterborne Ca and Cd, both independently and in combination, were examined in C. riparius larvae, which are extremely Cd tolerant. Larvae exposed to Ca (100-2500 {mu}mol L{sup -1}), exhibited classic Michaelis-Menten saturation kinetics for Ca influx, measured using {sup 45}Ca as a radio-tracer. The maximum rate of Ca influx (J{sub max}{sup Ca}) was 0.39 {mu}mol g{sup -1} h{sup -1}, and the Ca concentration where the carrier reached half saturation (K{sub M}{sup Ca}) was 289 {mu}mol L{sup -1}. Cd influx was measured using {sup 109}Cd as a radio-tracer in larvae exposed to Cd (0-1400 {mu}mol L{sup -1}) while the Ca concentration was set to the K{sub M}{sup Ca}. This revealed a J{sub max}{sup Cd} (2.26 {mu}mol g{sup -1} h{sup -1}) which was nearly 6-fold higher that of Ca. This unusually high capacity for Cd uptake is in accordance with the huge tissue Cd burdens that chironomid larvae are able to accumulate during high level exposures. The apparent K{sub M}{sup Cd} (1133 {mu}mol Cd L{sup -1}), when recalculated to account for the background Ca level, was still high (567 {mu}mol Cd L{sup -1}), suggesting that this organism has a low affinity for Cd relative to most aquatic animals, indeed lower or comparable to its affinity for Ca. In consequence, even well above environmentally relevant Cd exposures, C. riparius does not accumulate Cd at the expense of Ca, thereby avoiding internal hypocalcaemia, in contrast to most other organisms which are much more sensitive to Cd. However, Ca influx was significantly reduced when 1200 {mu}mol Cd L{sup -1} was added to Ca exposures (96-2410 {mu}mol L{sup -1}). Michaelis-Menten analysis revealed a similar J{sub max}{sup Ca} in Cd-exposed and control larvae (i.e. exposed only to Ca), but that the apparent K{sub M}{sup Ca} was many-fold higher in larvae which were simultaneously exposed to Ca and Cd. Conversely, increasing Ca concentrations (96-2410 {mu}mol L{sup -1}) progressively inhibited Cd uptake from a

  8. Effect of the cadmium chloride treatment on RF sputtered Cd{sub 0.6}Zn{sub 0.4}Te films for application in multijunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shimpi, Tushar M., E-mail: mechanical.tushar@gmail.com; Kephart, Jason M.; Swanson, Drew E.; Munshi, Amit H.; Sampath, Walajabad S. [Department of Mechanical Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, Colorado 80523 (United States); Abbas, A.; Walls, John M. [CREST (Centre for Renewable Energy Systems and Technology), Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2016-09-15

    Single phase Cd{sub 0.6}Zn{sub 0.4}Te (CdZnTe) films of 1 μm thickness were deposited by radio frequency planar magnetron sputter deposition on commercial soda lime glass samples coated with fluorine-doped tin oxide and cadmium sulphide (CdS). The stack was then treated with cadmium chloride (CdCl{sub 2}) at different temperatures using a constant treatment time. The effect of the CdCl{sub 2} treatment was studied using optical, materials, and electrical characterization of the samples and compared with the as-deposited CdZnTe film with the same stack configuration. The band gap deduced from Tauc plots on the as-deposited CdZnTe thin film was 1.72 eV. The deposited film had good crystalline quality with a preferred orientation along the {111} plane. After the CdCl{sub 2} treatment, the absorption edge shifted toward longer wavelength region and new peaks corresponding to cadmium telluride (CdTe) emerged in the x-ray diffraction pattern. This suggested loss of zinc after the CdCl{sub 2} treatment. The cross sectional transmission electron microscope images of the sample treated at 400 °C and the energy dispersive elemental maps revealed the absence of chlorine along the grain boundaries of CdZnTe and residual CdTe. The presence of chlorine in the CdTe devices plays a vital role in drastically improving the device performance which was not observed in CdZnTe samples treated with CdCl{sub 2}. The loss of zinc from the surface and incomplete recrystallization of the grains together with the presence of high densities of stacking faults were observed. The surface images using scanning electron microscopy showed that the morphology of the grains changed from small spherical shape to large grains formed due to the fusion of small grains with distinct grain boundaries visible at the higher CdCl{sub 2} treatment temperatures. The absence of chlorine along the grain boundaries, incomplete recrystallization and distinct grain boundaries is understood to cause the poor

  9. 3-D Modeling of Double-Diffusive Convection During Directional Solidification of a Non-Dilute Alloy with Application to the HgCdTe Growth Under Microgravity Conditions

    Science.gov (United States)

    Bune, Andris V.; Gillies, Donald C.; Lehoczky, Sandor L.

    1998-01-01

    A numerical calculation for a non-dilute alloy solidification was performed using the FIDAP finite element code. For low growth velocities plane front solidification occurs. The location and the shape of the interface was determined using melting temperatures from the HgCdTe liquidus curve. The low thermal conductivity of the solid HgCdTe causes thermal short circuit through the ampoule walls, resulting in curved isotherms in the vicinity of the interface. Double-diffusive convection in the melt is caused by radial temperature gradients and by material density inversion with temperature. Cooling from below and the rejection at the solid-melt interface of the heavier HgTe-rich solute each tend to reduce convection. Because of these complicating factors dimensional rather then non-dimensional modeling was performed. Estimates of convection contributions for various gravity conditions was performed parametrically. For gravity levels higher then 1 0 -7 of earth's gravity it was found that the maximum convection velocity is extremely sensitive to gravity vector orientation and can be reduced at least by factor of 50% for precise orientation of the ampoule in the microgravity environment. The predicted interface shape is in agreement with one obtained experimentally by quenching. The results of 3-D modeling are compared with previous 2-D finding. A video film featuring melt convection will be presented.

  10. The fatty acid profile of rainbow trout liver cells modulates their tolerance to methylmercury and cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Ferain, Aline, E-mail: aline.ferain@uclouvain.be [Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve (Belgium); Bonnineau, Chloé [Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve (Belgium); Irstea, UR MALY, Centre de Lyon-Villeurbanne, rue de la Doua 5/32108, F-69616 Villeurbanne (France); Neefs, Ineke; Rees, Jean François; Larondelle, Yvan [Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve (Belgium); Schamphelaere, Karel A.C.De [Laboratory of Environmental Toxicology and Aquatic Ecology, Environmental Toxicology Unit, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium); Debier, Cathy [Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve (Belgium)

    2016-08-15

    Highlights: • The phospholipid composition of rainbow trout liver cells was successfully changed. • Cell phospholipids influenced methylmercury (MeHg) and cadmium (Cd) toxicity. • Cells enriched in 18:3n-3, 20:5n-3 or 22:5n-6 were more resistant to MeHg and Cd. • Cell enrichment in 22:6n-3 increased resistance to Cd but not MeHg. - Abstract: The polyunsaturated fatty acid (PUFA) composition of fish tissues, which generally reflects that of the diet, affects various cellular properties such as membrane structure and fluidity, energy metabolism and susceptibility to oxidative stress. Since these cellular parameters can play an important role in the cellular response to organic and inorganic pollutants, a variation of the PUFA supply might modify the toxicity induced by such xenobiotics. In this work, we investigated whether the cellular fatty acid profile has an impact on the in vitro cell sensitivity to two environmental pollutants: methylmercury and cadmium. Firstly, the fatty acid composition of the rainbow trout liver cell line RTL-W1 was modified by enriching the growth medium with either alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), linoleic acid (LA, 18:2n-6), arachidonic acid (AA, 20:4n-6) or docosapentaenoic acid (DPA, 22:5n-6). These modified cells and their control (no PUFA enrichment) were then challenged for 24 h with increasing concentrations of methylmercury or cadmium. We observed that (i) the phospholipid composition of the RTL-W1 cells was profoundly modulated by changing the PUFA content of the growth medium: major modifications were a high incorporation of the supplemented PUFA in the cellular phospholipids, the appearance of direct elongation and desaturation metabolites in the cellular phospholipids as well as a change in the gross phospholipid composition (PUFA and monounsaturated fatty acid (MUFA) levels and n-3/n-6 ratio); (ii) ALA, EPA and DPA enrichment significantly

  11. Fabrication of polymer/cadmium sulfide hybrid solar cells [P3HT:CdS and PCPDTBT:CdS] by spray deposition.

    Science.gov (United States)

    Kumar, Neetesh; Dutta, Viresh

    2014-11-15

    This paper investigates fabrication of surfactant free CdS nanoparticles (NPs) and application in the fabrication of P3HT:CdS and PCPDTBT:CdS bulk-heterojunction hybrid solar cells using high-throughput, large-area, low cost spray deposition technique. Both the hybrid active layers and hole transport layers are deposited by spray technique. The CdS/Poly(3-hexylthiophene-2,5-diyl) (P3HT) and CdS/Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) hybrid devices are fabricated by spray deposition process at optimized conditions (i.e. film thickness, spray solution volume, distance between sample and spray nozzle, substrate temperature, etc.). The power conversion efficiency of η=0.6% and 1.02% is obtained for P3HT:CdS and PCPDTBT:CdS hybrid devices, respectively. Spray coating holds significant promise as a technique capable of fabricating large-area, high performance hybrid solar cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Sonochemical synthesis and DFT studies of nano novel Schiff base cadmium complexes: Green, efficient, recyclable catalysts and precursors of Cd NPs

    Science.gov (United States)

    Parsaee, Zohreh

    2017-10-01

    Novel asymmetric (N4) Schiff bases (Ln, n = 1-3) and their nanosized cadmium complexes derived of 4,4'-(pentylazanediyl) dibenzaldehyde and aminobenzaldehyde are synthesized by sonochemical method and characterized based on physicochemical analysis including 1H NMR, 13C NMR, SEM, TGA, Mass, FT-IR, UV-Vis spectroscopy, elemental analysis, magnetic moment and molar conductance measurements. According to the analytic results of the NMR, UV-Vis and magnetic moment studies, it is found that the geometrical structures of these complexes [CdII2LnCl4], (L = C45H40N5X, X = CH3, Cl, OH) are square planer. The synthesized complexes were so effective as nanocatalyst on the oxidation of primary and secondary alcohols. The oxidation reactions were carried out in ethyl-methyl-imidazolium ionic liquid in presence of NaOCl. In addition Cd NPs were synthesized through the thermal decomposition of mentioned complexes and characterized by using FT-IR, SEM, TEM, EDX and XRD methods, which indicated close accordance to the standard pattern of CdO nanoparticles and an acceptable size at the nanorange (22-27 nm). Furthermore geometrical optimization of the Cd2LnCl4 calculated using DFT/B3LYP with LanL2DZ/6-311+G (d,p) level. The electronic parameter including HOMO-LUMO orbitals, bond gap, chemical hardness-softness, electronegativity, electrophilicity, NMR chemical shifts and IR frequencies were calculated. The calculated NMR shifts and vibrational frequencies showed excellent agreement with experimental data.

  13. New five coordinated supramolecular structured cadmium complex as precursor for CdO nanoparticles: Synthesis, crystal structure, theoretical and 3D Hirshfeld surface analyses

    Science.gov (United States)

    Ghanbari Niyaky, S.; Montazerozohori, M.; Masoudiasl, A.; White, J. M.

    2017-03-01

    In this paper, a combined experimental and theoretical study on a new CdLBr2 complex (L = N1-(2-bromobenzylidene)-N2-(2-((E)-(2-bromobenzylidene) amino)ethyl) ethane-1,2-diamine) synthesized via template method, is described. The crystal structure analysis of the complex indicates that, the Cd(II) ion is centered in a distorted square pyramidal space constructed by three iminic nitrogens of the ligand as well as two bromide anions. More analysis of crystal packing proposed a supramolecular structure stabilized by some non-covalent interactions such as Br⋯Br and Xsbnd H⋯Br (X = N and C) in solid state. Furthermore, 3D Hirshfeld surface analyses and DFT studies were applied for theoretical investigation of the complexes. Theoretical achievements were found in a good agreement with respect to the experimental data. To evaluate the nature of bonding and the strength of the intra and inter-molecular interactions a natural bond orbital (NBO) analysis on the complex structure was performed. Time dependent density functional theory (TD-DFT) was also applied to predict the electronic spectral data of the complex as compared with the experimental ones. CdLBr2 complex as nano-structure compound was also prepared under ultrasonic conditions and characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). Finally, it was found that the cadmium complex can be used as a suitable precursor for preparation of CdO nanoparticles via calcination process at 600 °C under air atmosphere.

  14. Radiation Characterization Summary: ACRR Cadmium-Polyethylene (CdPoly) Bucket Located in the Central Cavity on the 32-Inch Pedestal at the Core Centerline

    Energy Technology Data Exchange (ETDEWEB)

    Parma, Edward J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naranjo, Gerald E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kaiser, Krista Irene [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Arnold, James F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lippert, Lance L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clovis, Ralph D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Lonnie E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Quirk, Thomas J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-10-01

    This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the cadmium-polyethylene (CdPoly) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-CdPoly-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to Drew Tonigan for helping field the activation experiments in ACRR, David Samuel for helping to finalize the drawings and get the parts fabricated, and Elliot Pelfrey for preparing the active dosimetry plots.

  15. Radiation Characterization Summary: ACRR Cadmium-Polyethylene (CdPoly) Bucket Located in the Central Cavity on the 32-Inch Pedestal at the Core Centerline.

    Energy Technology Data Exchange (ETDEWEB)

    Parma, Edward J.,; Naranjo, Gerald E.; Kaiser, Krista Irene; Arnold, James F.; Lippert, Lance L.; Clovis, Ralph D.; Martin, Lonnie E.; Quirk, Thomas J.; Vehar, David W.

    2016-10-01

    This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the cadmium-polyethylene (CdPoly) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-CdPoly-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to Drew Tonigan for helping field the activation experiments in ACRR, David Samuel for helping to finalize the drawings and get the parts fabricated, and Elliot Pelfrey for preparing the active dosimetry plots.

  16. Synthesis, Structure and Fluorescent Property of a Novel 2-D Sheet Inorganic-organic Hybrid Cadmium Polymer [CdBr2(bpdo)]n

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel 2-D sheet inorganic-organic hybrid cadmium polymer, [CdBr2(bpdo)]n (bpdo = N,N'-O,O-4,4'-bipyridine) has been hydrothermally synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The crystal crystallizes in monoclinic, space group C2/c, with a = 16.336(3), b = 3.9904(5), c = 18.479(3) (A), β = 91.640(6)°, Mr = 460.40, V = 1204.1(3) (A)3, Z = 4, Dc = 2.540 g/cm3, μ = 8.439 mm-1, F(000) = 864, R = 0.0314 and wR = 0.0733 for 1069 observed reflections (I>2σ(I)). X-ray diffraction reveals that the title compound consists of the 2-D inorganic-organic hybrid sheet constructed from [CdBr2]n chains and bpdo bridges in the packing motif of …ABAB…. The title compound exhibits intense blue photoluminescence in the solid state at room temperature.

  17. 重金属镉(Cd)在植物体内的转运途径及其调控机制%Transport pathways of cadmium (Cd) and its regulatory mechanisms in plant

    Institute of Scientific and Technical Information of China (English)

    王晓娟; 王文斌; 杨龙; 金樑; 宋瑜; 姜少俊; 秦兰兰

    2015-01-01

    重金属镉( Cd)的毒害效应与其由土壤向植物地上部分运输有关,揭示Cd2+转运途径及其调控机制可为提高植物抗镉性以及镉污染的植物修复提供依据。对Cd2+在植物体内的转运途径,特别是限制Cd2+移动的细胞结构和分子调控机制研究进展进行了回顾。 Cd2+通过共质体和质外体途径穿过根部皮层进入木质部的过程中,大部分在皮层细胞间沉积,少部分抵达中柱后转移到地上部分。为了免受Cd2+的危害,植物体产生了多种限制Cd2+吸收和转移的生理生化机制:1)环绕在内皮层径向壁和横向壁上的凯氏带阻止Cd2+以质外体途径进入木质部;2)螯合剂与进入根的Cd2+螯合形成稳定化合物并区隔在液泡中;3)通过H+/Cd2+离子通道等将Cd2+逆向转运出根部。植物共质体和质外体途径转运重金属镉的能力以及两条途径的串扰尚待进一步明晰和阐明。%Heavy metal ( HM ) toxicity is a worldwide concern because it damages plants by altering their major physiological and metabolic processes. The heavy metal cadmium ( Cd) is a nonessential element, and is a valid inhibitor of plant growth. The toxic effect of cadmium is closely related to its transfer from the soil to the plant above ground parts. Understanding the transport pathway and regulatory mechanism of cadmium in plants may improve plant resistance to this heavy metal, in addition to providing a theoretical basis for the phytoremediation soils contaminated by cadmium. In this paper, we reviewed the transport pathways of Cd2+ in plants and what limits its mobility based on the cytological structural and molecular regulation mechanism of plants. As the main organ for transporting water and nutrients to the plant body, the plant root is also the main organ that absorbs toxic metals, such as cadmium. During the process of Cd2+ transfer from the root cortex to the xylem, most Cd2+is deposited between the cells of the

  18. RISK ASSESSMENT AND MANAGEMENT OF ENVIRONMENTAL CADMIUM

    Science.gov (United States)

    Cadmium consumed in foods grown on soils contaminated by industrial Cd+Zn discharge has caused renal tubular dysfunction in exposed humans in discrete situations. However, lack of understanding about environmental Cd has caused wide concern that generalpopulations may...

  19. Stoichiometry, thickness and crystallinity of MOCVD grown Hg{sub 1x-y}Cd{sub x}Mn{sub y}Te determined by nuclear techniques of analysis

    Energy Technology Data Exchange (ETDEWEB)

    Studd, W.B.; Johnston, P.N.; Bubb, I.F. [Royal Melbourne Inst. of Tech., VIC (Australia); Leech, P.W. [Applied Research and Developement, Telecom Australia, Clayton, VIC (Australia)

    1993-12-31

    The quaternary semi-conductor Hg{sub 1-x-y}Cd{sub x}Mn{sub y}Te has been grown by Metal Organic Chemical Vapour Deposition using the Interdiffused Multi-layer Process. The layers have been analysed by Ion beam (PIXE, RBS, channeling) and related analytical techniques (EDXRF, XRD, RHEED) to obtain stoichiometric and structural information. The analysis shows that all four elements are present throughout the layer and that the elemental concentrations and thickness of the layer vary considerably over the film. Channeling, XRD and RHEED have been combined to show that the layer is polycrystalline. 14 refs., 3 figs.

  20. A 1.5k x 1.5k class photon counting HgCdTe linear avalanche photo-diode array for low background space astronomy in the 1-5micron infrared

    Science.gov (United States)

    Hall, Donald

    Under a current award, NASA NNX 13AC13G "EXTENDING THE ASTRONOMICAL APPLICATION OF PHOTON COUNTING HgCdTe LINEAR AVALANCHE PHOTODIODE ARRAYS TO LOW BACKGROUND SPACE OBSERVATIONS" UH has used Selex SAPHIRA 320 x 256 MOVPE L-APD HgCdTe arrays developed for Adaptive Optics (AO) wavefront (WF) sensing to investigate the potential of this technology for low background space astronomy applications. After suppressing readout integrated circuit (ROIC) glow, we have placed upper limits on gain normalized dark current of 0.01 e-/sec at up to 8 volts avalanche bias, corresponding to avalanche gain of 5, and have operated with avalanche gains of up to several hundred at higher bias. We have also demonstrated detection of individual photon events. The proposed investigation would scale the format to 1536 x 1536 at 12um (the largest achievable in a standard reticule without requiring stitching) while incorporating reference pixels required at these low dark current levels. The primary objective is to develop, produce and characterize a 1.5k x 1.5k at 12um pitch MOVPE HgCdTe L-APD array, with nearly 30 times the pixel count of the 320 x 256 SAPHIRA, optimized for low background space astronomy. This will involve: 1) Selex design of a 1.5k x 1.5k at 12um pitch ROIC optimized for low background operation, silicon wafer fabrication at the German XFab foundry in 0.35 um 3V3 process and dicing/test at Selex, 2) provision by GL Scientific of a 3-side close-buttable carrier building from the heritage of the HAWAII xRG family, 3) Selex development and fabrication of 1.5k x 1.5k at 12 um pitch MOVPE HgCdTe L-APD detector arrays optimized for low background applications, 4) hybridization, packaging into a sensor chip assembly (SCA) with initial characterization by Selex and, 5) comprehensive characterization of low background performance, both in the laboratory and at ground based telescopes, by UH. The ultimate goal is to produce and eventually market a large format array, the L

  1. Cadmium status in Egypt

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    It is inferred from these studies that releases of Cd are still increasing and it is recommended that measures must be taken to reduce emissions of cadmium. Any cadmium discharged into the Egyptian environment may move from one compartment to another at varying rates,resulting in an accumulation in compartments such as soils and biota. Such accumulation can be expected to increase with continued emissions,and attention should be given to all sources of cadmium, natural as well as anthropogenic especially in the industrial cities in Egypt. Cadmium present in sewage, as well as industrial effluent (also, other liquid and solid wastes) and sewage sludge will increase levels in soils and is xpected to contribute to dietary levels and body burdens. The current information indicates that such effects may have to be evaluated over long periods of time, possibly as long as 50 - 100 years.

  2. Cadmium Alternatives

    Science.gov (United States)

    2012-08-01

    accessories) and be non- reflective Cadmium Replacements – Zinc Nickel Passivated Zinc Nickel Non-hex chrome passivate of high interest, but...for Change Cadmium passivated with hexavalent chromium has been in use for many decades Cadmium is toxic , and is classified as a priority...including cadmium! Cadmium Replacements (With MIL-DTL-38999 Designations) Zn/Ni (Class Z) Per ASTM B 841, type D (black) Electroless Nickel plus

  3. Lead, mercury, and cadmium exposure and attention deficit hyperactivity disorder in children

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Stephani [Division of Epidemiology and Biostatistics, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH 45267 (United States); Arora, Monica [Department of Psychiatry, Creighton University School of Medicine, Omaha, NE 68131 (United States); Fernandez, Cristina [Department of Pediatrics, Creighton University School of Medicine, Omaha, NE 68131 (United States); Landero, Julio; Caruso, Joseph [Metallomics Center, Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221 (United States); Chen, Aimin, E-mail: aimin.chen@uc.edu [Division of Epidemiology and Biostatistics, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH 45267 (United States)

    2013-10-15

    Background: There is limited research examining the relationship between lead (Pb) exposure and medically diagnosed attention deficit hyperactivity disorder (ADHD) in children. The role of mercury (Hg) and cadmium (Cd) exposures in ADHD development is even less clear. Objectives: To examine the relationship between Pb, Hg, and Cd and ADHD in children living inside and outside a Lead Investigation Area (LIA) of a former lead refinery in Omaha, NE. Methods: We carried out a case-control study with 71 currently medically diagnosed ADHD cases and 58 controls from a psychiatric clinic and a pediatric clinic inside and outside of the LIA. The participants were matched on age group (5–8, 9–12 years), sex, race (African American or Caucasians and others), and location (inside or outside LIA). We measured whole blood Pb, total Hg, and Cd using inductively coupled plasma mass spectrometry. Results: Inside the LIA, the 27 cases had blood Pb geometric mean (GM) 1.89 µg/dL and the 41 controls had 1.51 µg/dL. Outside the LIA, the 44 cases had blood Pb GM 1.02 µg/dL while the 17 controls had 0.97 µg/dL. After adjustment for matching variables and maternal smoking, socioeconomic status, and environmental tobacco exposure, each natural log unit blood Pb had an odds ratio of 2.52 with 95% confidence interval of 1.07–5.92. Stratification by the LIA indicated similar point estimate but wider CIs. No associations were observed for Hg or Cd. Conclusions: Postnatal Pb exposure may be associated with higher risk of clinical ADHD, but not the postnatal exposure to Hg or Cd. -- Highlights: • Blood Pb levels are associated with ADHD diagnosis in children. • No association was found between blood Cd or Hg levels and ADHD. • Children living close to hazardous waste site need to reduce metal exposure.

  4. Cadmium content of plants as affected by soil cadmium concentration

    Energy Technology Data Exchange (ETDEWEB)

    Lehoczky, E. [Pannon Univ. of Agricultural Sciences, Keszthely (Hungary); Szabados, I.; Marth, P. [Plant Health and Soil Conservation Station, Higany (Hungary)

    1996-12-31

    Pot experiments were conducted in greenhouse conditions to study the effects of increasing cadmium (Cd) levels on biomass production and Cd contents in corn, (Zea mays L.), garlic (Allium sativum L.), and spinach (Spinacia oleracea L.). Plants were grown in two soil types: Eutric cambisol soil and A gleyic luvisol soil. Spinach proved to be the most sensitive to Cd treatments as its biomass considerably decreased with the increasing Cd levels. Cadmium contents of the three crops increased with increasing levels of Cd applications. Statistical differences were observed in the Cd contents of crops depending on soil type. With the same Cd rates, Cd tissue concentration of test plants grown in the strongly acidic Gleyic luvisol soil were many times higher than that of plants grown in a neutral Eutric cambisol soil. 14 refs., 4 tabs.

  5. Application of the ALE and MBE Methods to the Growth of Layered Hg sub x Cd sub 1-x Te Films.

    Science.gov (United States)

    1986-09-26

    Devices. edited by M. A. Her- 𔃽 T. Cheung. M. Khoshenexnsan. and T J Magee, App] Phys [ett 43, man (PWN-Polish Science Publishing, Warsaw. 1983). p...into two categories, depending on %hether the speciesir transported physicall , kr chernicillk to the deessi . ,iLiqu.d Field Sold FieldO)× In the...Polis. material nearly ideal for infrared device applications. The Academy of Sciences , Warsaw) for stimulating discussions need for large-area Hg

  6. Temperature dependence of the fundamental band gap parameters in cadmium-rich ZnCd1-Se using photoluminescence spectroscopy

    Indian Academy of Sciences (India)

    Lalita Gupta; S Rath; S C Abbi; F C Jain

    2003-10-01

    Thin films of ternary ZnCd1-Se were deposited on GaAs (100) substrate using metal-organic-chemical-vapour-deposition (MOCVD) technique. Temperature dependence of the near-band-edge emission from these Cd-rich Zn Cd1-Se (for = 0.025, 0.045) films has been studied using photoluminescence spectroscopy. Relevant parameters that describe temperature variation of the energy and broadening of the fundamental band gap have been evaluated using various models including the two-oscillator model, the Bose–Einstein model and the Varshni model. While all these models suffice to explain spectra at higher temperatures, the two-oscillator model not only explains low temperature spectra adequately but also provides additional information concerning phonon dispersion in these materials.

  7. Hydrothermal synthesis and crystal structure analysis of two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79

    Directory of Open Access Journals (Sweden)

    N. Kumada

    2015-09-01

    Full Text Available Two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79, were prepared by hydrothermal reaction using NaBiO3·nH2O as one of the starting compounds. The crystal structures of these compounds were refined by using synchrotron X-ray powder diffraction data. The former bismuthate has a MnSb2O6-type structure with a hexagonal cell (space group: P321; the cell parameters were a = 9.3641(7 and c = 4.9523(3 Å, and the final R-factors were Rwp = 4.59% and Rp = 3.04%. The latter bismuthate has a fluorite-type structure with a cubic cell (space group: Fm3¯m of a = 5.4110(4 Å, and the final R-factors were Rwp = 4.79% and Rp = 3.57%. These new bismuthates exhibit no photocatalytic activity under visible light.

  8. Survey of mercury, cadmium and lead content of household batteries.

    Science.gov (United States)

    Recknagel, Sebastian; Radant, Hendrik; Kohlmeyer, Regina

    2014-01-01

    The objective of this work was to provide updated information on the development of the potential impact of heavy metal containing batteries on municipal waste and battery recycling processes following transposition of the new EU Batteries Directive 2006/66/EC. A representative sample of 146 different types of commercially available dry and button cells as well as lithium-ion accumulators for mobile phones were analysed for their mercury (Hg)-, cadmium (Cd)- and lead (Pb)-contents. The methods used for preparing the cells and analysing the heavy metals Hg, Cd, and Pb were either developed during a former study or newly developed. Several batteries contained higher mass fractions of mercury or cadmium than the EU limits. Only half of the batteries with mercury and/or lead fractions above the marking thresholds were labelled. Alkaline-manganese mono-cells and Li-ion accumulators, on average, contained the lowest heavy metal concentrations, while zinc-carbon batteries, on average, contained the highest levels.

  9. Speciation of Dissolved Cadmium

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Andersen, Sjur; Christensen, Thomas Højlund

    1995-01-01

    Equilibrium dialysis and ion exchange methods, as well as computer calculations (GEOCHEM), were applied for speciation of dissolved cadmium (Cd) in test solutions and leachate samples. The leachate samples originated from soil, compost, landfill waste and industrial waste. The ion exchange (IE...

  10. Spectroscopic, DNA binding ability, biological activity, DFT calculations and non linear optical properties (NLO) of novel Co(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes with ONS Schiff base

    Science.gov (United States)

    Abdel Aziz, Ayman A.; Elantabli, Fatma M.; Moustafa, H.; El-Medani, Samir M.

    2017-08-01

    The reaction of Co(II), Cu(II), Zn(II), Cd(II) and Hg(II) with the synthesized N-(2-hydroxy-1-naphthylidene)-2-aminothiophenol Schiff base ligand (H2L) at room temperature resulted in the formation of the five complexes; [Co(HL)2]H2O, 1; [M(HL)2] (M = Cu, Zn and Cd), (2-4) and [Hg(HL)Cl], 5. The ligand and its complexes were characterized based on elemental analyses, IR, 1H NMR, magnetic measurement, molar conductance, and thermal analysis. Coats and Redfern method was used to compute the kinetic and thermodynamic parameters. Antimicrobial activities of H2L and its complexes have been studied. The binding of Co(II), Cu(II) and Zn(II) complexes to calf thymus DNA (CT-DNA) has been investigated using UV-Vis and fluorescence absorption spectra. The results indicated that the ligand and its complexes may bind to DNA by intercalation modes, with a much higher binding affinity of the complexes than that of the ligand. The equilibrium geometries of the studied complexes are investigated theoretically at the B3LYP/LANL2DZ level of theory, and it was found that these geometries are non-linear. The calculated EHOMO and ELUMO energies of the studied complexes can be used to calculate the global properties. The calculated nonlinear optical parameters (NLO); first order hyperpolarizibility (β) of the studied complexes show promising optical properties.

  11. Impact of D2O/H2O Solvent Exchange on the Emission of HgTe and CdTe Quantum Dots: Polaron and Energy Transfer Effects.

    Science.gov (United States)

    Wen, Qiannan; Kershaw, Stephen V; Kalytchuk, Sergii; Zhovtiuk, Olga; Reckmeier, Claas; Vasilevskiy, Mikhail I; Rogach, Andrey L

    2016-04-26

    We have studied light emission kinetics and analyzed carrier recombination channels in HgTe quantum dots that were initially grown in H2O. When the solvent is replaced by D2O, the nonradiative recombination rate changes highlight the role of the vibrational degrees of freedom in the medium surrounding the dots, including both solvent and ligands. The contributing energy loss mechanisms have been evaluated by developing quantitative models for the nonradiative recombination via (i) polaron states formed by strong coupling of ligand vibration modes to a surface trap state (nonresonant channel) and (ii) resonant energy transfer to vibration modes in the solvent. We conclude that channel (i) is more important than (ii) for HgTe dots in either solution. When some of these modes are removed from the relevant spectral range by the H2O to D2O replacement, the polaron effect becomes weaker and the nonradiative lifetime increases. Comparisons with CdTe quantum dots (QDs) served as a reference where the resonant energy loss (ii) a priori was not a factor, also confirmed by our experiments. The solvent exchange (H2O to D2O), however, is found to slightly increase the overall quantum yield of CdTe samples, probably by increasing the fraction of bright dots in the ensemble. The fundamental study reported here can serve as the foundation for the design and optimization principles of narrow bandgap quantum dots aimed at applications in long wavelength colloidal materials for infrared light emitting diodes and photodetectors.

  12. Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water.

    Science.gov (United States)

    Guo, Xiaoyao; Du, Bin; Wei, Qin; Yang, Jian; Hu, Lihua; Yan, Liangguo; Xu, Weiying

    2014-08-15

    In the present study, a kind of graphenes magnetic material (Fe3O4-GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effective for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pHZPC value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe3O4-GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g(-1) for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature.

  13. Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base

    Science.gov (United States)

    Halli, Madappa B.; Sumathi, R. B.

    2012-08-01

    A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

  14. Handelsgødnings indflydelse på afgrøders indhold af arsen, bly, cadmium, krom, kviksølv og nikkel

    DEFF Research Database (Denmark)

    Christensen, Bent Tolstrup; Elsgaard, Lars

    Denne rapport belyser indholdet af arsen (As), bly (Pb), cadmium (Cd), krom (Cr), kviksølv (Hg) og nikkel (Ni) i afgrøder, der er dyrket ved forskellige niveauer af handelsgødning (fra ugødet til to gange normal gødskning). Effekten af handelsgødning er sammenlignet med effekten af husdyrgødning...

  15. Effects of cadmium and mercury on the upper part of skeletal muscle glycolysis in mice.

    Directory of Open Access Journals (Sweden)

    Maria José Ramírez-Bajo

    Full Text Available The effects of pre-incubation with mercury (Hg(2+ and cadmium (Cd(2+ on the activities of individual glycolytic enzymes, on the flux and on internal metabolite concentrations of the upper part of glycolysis were investigated in mouse muscle extracts. In the range of metal concentrations analysed we found that only hexokinase and phosphofructokinase, the enzymes that shared the control of the flux, were inhibited by Hg(2+ and Cd(2+. The concentrations of the internal metabolites glucose-6-phosphate and fructose-6-phosphate did not change significantly when Hg(2+ and Cd(2+ were added. A mathematical model was constructed to explore the mechanisms of inhibition of Hg(2+ and Cd(2+ on hexokinase and phosphofructokinase. Equations derived from detailed mechanistic models for each inhibition were fitted to the experimental data. In a concentration-dependent manner these equations describe the observed inhibition of enzyme activity. Under the conditions analysed, the integral model showed that the simultaneous inhibition of hexokinase and phosphofructokinase explains the observation that the concentrations of glucose-6-phosphate and fructose-6-phosphate did not change as the heavy metals decreased the glycolytic flux.

  16. Radioactive zinc ( sup 65 Zn), zinc, cadmium, and mercury in the Pacific Hake, Merluccius productus (Ayres), off the West Coast of the United States

    Energy Technology Data Exchange (ETDEWEB)

    Naidu, J.R.

    1974-06-01

    The Pacific Hake, Merluccius productus (Ayers) was used to monitor the waters off Puget Sound and the West Coast of the US for zinc(Zn), cadmium(Cd), mercury(Hg) and {sup 65}Zn. The Columbia River is not the source of Zn, Cd or Hg contamination, but is the source of {sup 65}Zn, with the concentration in the Hake reflecting the position of the Columbia River plume. Zn and Cd accumulation in the Hake were fit to the equation Y=B{sub 1}+B{sub 2}e{sup B}{sub 3}X where Y is the concentration of the element and X is the length or weight of the fish. Biological attributes were assigned to the other parameters as follows: B{sub 1} is the asymptotic value for Zn or Cd at chemical maturity; B{sub 2} is the location of the curve with respect to the length or weight of the fish; and B{sub 3} is a constant pertaining to the rate of change of Zn or Cd. Although Zn, Cd and Hg are all Group 2B elements, only the concentrations of Zn and Cd were correlated for all locations; Hg concentrations varied as a function of location. Zn and Cd concentrations increase with fish size and approach an asymptotic value at maturity, while Hg concentrations were linear and the slope is a function of sampling location. Zn and Cd levels are regulated in the adult, while Hg continues to increase with age. It may be significant that the age distribution of fish caught commercially coincides with the maximum concentration of Zn and Cd. 195 refs., 30 figs., 10 tabs. (MHB)

  17. Optical and magnetic properties of monophasic cadmium ferrite (CdFe{sub 2}O{sub 4}) nanostructure prepared by thermal treatment method

    Energy Technology Data Exchange (ETDEWEB)

    Naseri, Mahmoud, E-mail: mahmoud.naseri55@gmail.com

    2015-10-15

    This paper reports optical and magnetic properties of CdFe{sub 2}O{sub 4} nanostructure which was prepared by a simple thermal treatment method. Calcination was conducted at temperatures between 673 and 773 K, and final products had different crystallite sizes ranging from 47 to 138 nm. The influence of calcination temperature on the degree of crystallinity, microstructure, and phase composition was investigated by different characterization techniques, i.e., X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and Fourier transform infrared spectroscopy (FT-IR), respectively. The compositions of the samples were determined by Energy dispersive X-ray analysis (EDXA). The effect of calcination temperature on band gap energy was studied by UV–vis absorption spectra. The formed nanostructures exhibited ferromagnetic behaviors with unpaired electrons spins, which was confirmed by using vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy. - Highlights: • Metal nitrates were added into an aqueous solution of PVA and the mixed solution was heated at 373 K. • The effect of calcination temperature on morphology of cadmium ferrite nanostructures was characterized. • Elemental composition, phase composition and others properties were investigated.

  18. Cellular model for studying accommodation to environmental stressors: protection and potentiation by cadmium and other metals

    Energy Technology Data Exchange (ETDEWEB)

    Chin, B.; Lesowitz, G.S.; Bernstein, I.A.

    1978-01-01

    Exposure of Physarum polycephalum to a subthreshold challenge of Cd/sup 2 +/, which did not delay mitosis, elicited a protective response against a mitotic delay resulting from subsequent exposure to a suprathreshold challenge of Cd/sup 2 +/. Some characteristics of this protective response are herein identified. The concentration of Cd/sup 2 +/ in the subthreshold challenge could be lowered to 10/sup -5/ M and maintain complete protection against a suprathreshold challenge of 5 x 10/sup -4/ M Cd/sup 2 +/. A subthreshold challenge of 10/sup -4/ M provided full protection against a Cd2/sup +/ concentration of 7 x 10/sup -4/ M. A subthreshold challenge of 10/sup -4/ M Cd/sup 2 +/ could be placed anywhere in the cell cycle approaching but not abutting a suprathreshold challenge of 5 x 10/sup -4/ M Cd/sup 2 +/ in late G/sub 2/ and still provide complete protection with the exception of one point in early S. At that point, 10/sup -4/ M Cd/sup 2 +/ by itself was toxic to the cell; partial protection, however, developed. Other responses developed when metals were substituted for cadmium. Cd/sup 2 +/ protected against exposure to Hg/sup 2 +/ and Ni/sup 2 +/ but potentiated exposures to Co/sup 2 +/, Cu/sup 2 +/, Pb/sup 2 +/, or Zn/sup 2 +/. A curious observation is that exposure to Hg/sup 2 +/ and Ni/sup 2 +/ protected against exposure to Cd/sup 2 +/, while exposure to Co/sup 2 +/, Pb/sup 2 +/, or Zn/sup 2 +/ potentiated exposure to Cd/sup 2 +/, Hg/sup 2 +/ and Ni/sup 2 +/ protected against reexposure to themselves.

  19. Low-Cost Lattice Matching Zn(Se)Te/Si Composite Substrates for HgCdSe and Type-2 Superlattices

    Science.gov (United States)

    2013-09-01

    which thin ZnTe grown on Si is used as a buffer layer to bridge the lattice 2 parameter gap between Si and CdTe , we believe that high quality...ZnSeTe. To date, the only research on ZnTe growth on Si has been related to the nucleation thin ZnTe buffer layer used for growing high quality CdTe ...Considering light passing through a thin film , the thickness (t) of the thin film can be expressed as a function of the interference fringe separation (Δ

  20. CdS thin films obtained by thermal treatment of cadmium(II) complex precursor deposited by MAPLE technique

    Energy Technology Data Exchange (ETDEWEB)

    Rotaru, Andrei [INFLPR - National Institute for Laser, Plasma and Radiation Physics, PPAM - Lasers Department, 409 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania); Mietlarek-Kropidlowska, Anna [Gdansk University of Technology, Chemistry Faculty, 11/12 G. Narutowicza Str., PL-90-233 Gdansk (Poland); Constantinescu, Catalin, E-mail: catalin.constantinescu@inflpr.ro [INFLPR - National Institute for Laser, Plasma and Radiation Physics, PPAM - Lasers Department, 409 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania); Scarisoreanu, Nicu; Dumitru, Marius [INFLPR - National Institute for Laser, Plasma and Radiation Physics, PPAM - Lasers Department, 409 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania); Strankowski, Michal [Gdansk University of Technology, Chemistry Faculty, 11/12 G. Narutowicza Str., PL-90-233 Gdansk (Poland); Rotaru, Petre [University of Craiova, Faculty of Physics, 13 A.I. Cuza St., Craiova RO-200585, Dolj (Romania); Ion, Valentin [INFLPR - National Institute for Laser, Plasma and Radiation Physics, PPAM - Lasers Department, 409 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania); Vasiliu, Cristina [INOE 2000 - National Institute for Optoelectronics, 1 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania); Becker, Barbara [Gdansk University of Technology, Chemistry Faculty, 11/12 G. Narutowicza Str., PL-90-233 Gdansk (Poland); Dinescu, Maria [INFLPR - National Institute for Laser, Plasma and Radiation Physics, PPAM - Lasers Department, 409 Atomistilor Bvd., Magurele RO-077125, Bucharest (Romania)

    2009-05-15

    Thin films of [Cd{l_brace}SSi(O-Bu{sup t}){sub 3}{r_brace}(S{sub 2}CNEt{sub 2})]{sub 2}, precursor for semiconducting CdS layers, were deposited on silicon substrates by Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Structural analysis of the obtained films by Fourier transform infrared spectroscopy (FTIR) confirmed the viability of the procedure. After the deposition of the coordination complex, the layers are manufactured by appropriate thermal treatment of the system (thin film and substrate), according to the thermal analysis of the compound. Surface morphology of the thin films was investigated by atomic force microscopy (AFM) and spectroscopic-ellipsometry (SE) measurements.

  1. Cadmium, lead and mercury exposure in non smoking pregnant women

    Energy Technology Data Exchange (ETDEWEB)

    Hinwood, A.L., E-mail: a.hinwood@ecu.edu.au [Centre for Ecosystem Management, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027 (Australia); Callan, A.C.; Ramalingam, M.; Boyce, M. [Centre for Ecosystem Management, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027 (Australia); Heyworth, J. [School Population Health, The University of Western Australia, 35 Stirling Highway Crawley, WA 6009 (Australia); McCafferty, P. [ChemCentre, PO Box 1250, Bentley, WA 6983 (Australia); Odland, J.Ø. [Department of Community Medicine, University of Tromsø, N-9037 Tromsø (Norway)

    2013-10-15

    Recent literature suggests that exposure to low concentrations of heavy metals may affect both maternal and child health. This study aimed to determine the biological heavy metals concentrations of pregnant women as well as environmental and dietary factors that may influence exposure concentrations. One hundred and seventy three pregnant women were recruited from Western Australia, each providing a sample of blood, first morning void urine, residential soil, dust and drinking water samples. Participants also completed a questionnaire which included a food frequency component. All biological and environmental samples were analysed for heavy metals using ICP-MS. Biological and environmental concentrations of lead and mercury were generally low (Median Pb Drinking Water (DW) 0.04 µg/L; Pb soil <3.0 µg/g; Pb dust 16.5 µg/g; Pb blood 3.67 µg/L; Pb urine 0.55; µg/L Hg DW <0.03; Hg soil <1.0 µg/g; Hg dust <1.0 µg/g; Hg blood 0.46 µg/L; Hg urine <0.40 µg/L). Cadmium concentrations were low in environmental samples (Median CdDW 0.02 µg/L; Cdsoil <0.30 ug/g; Cddust <0.30) but elevated in urine samples (Median 0.55 µg/L, creatinine corrected 0.70 µg/g (range <0.2–7.06 µg/g creatinine) compared with other studies of pregnant women. Predictors of increased biological metals concentrations in regression models for blood cadmium were residing in the Great Southern region of Western Australia and not using iron/folic acid supplements and for urinary cadmium was having lower household annual income. However, these factors explained little of the variation in respective biological metals concentrations. The importance of establishing factors that influence low human exposure concentrations is becoming critical in efforts to reduce exposures and hence the potential for adverse health effects. -- Highlights: • Biological heavy metals concentrations in women in their 3rd trimester of pregnancy. • Exposure assessment including environmental, lifestyle and activity

  2. Human exposure to lead, cadmium and mercury through fish and seafood product consumption in Italy: a pilot evaluation.

    Science.gov (United States)

    Pastorelli, A A; Baldini, M; Stacchini, P; Baldini, G; Morelli, S; Sagratella, E; Zaza, S; Ciardullo, S

    2012-01-01

    The presence of selected toxic heavy metals, such as cadmium (Cd), lead (Pb) and mercury (Hg), was investigated in fish and seafood products, namely, blue mussel, carpet shell clam, European squid, veined squid, deep-water rose shrimp, red mullet, European seabass, gilthead seabream, Atlantic cod, European hake, Atlantic bluefin tuna and swordfish so as to assess their human exposure through diet. Metals were detected by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and hydride generation atomic absorption spectrometry (Hg-AAS). Measurements of Cd, Pb and Hg were performed by means of analytical methods validated in compliance with UNI CEI EN ISO/IEC 17025 [2005. General requirements for the competence of testing and calibration laboratories. Milano (Italy): UNI Ente Nazionale Italiano di Unificazione]. The exposure assessment was undertaken matching the levels of Cd, Pb and total Hg with consumption data related to fish and seafood products selected for this purpose. In order to establish human health implications, the estimated weekly intakes (EWIs) for Cd, Pb and Hg were compared with the standard tolerable weekly intakes (TWI) for Cd and provisional tolerable weekly intakes (PTWIs) for Pb and Hg stipulated by the European Food Safety Authority (EFSA) and the Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Expert Committee on Food Additives (JECFA). The found metal concentrations were largely below the maximum levels (MLs) established at the European Union level with the exception of Cd. This metal exceeded the MLs in squid, red mullet, European hake and Atlantic cod. Squid and blue mussel showed the highest Pb concentrations which accounted for 60% and 10% of the MLs, respectively. Highest Hg levels were found in predatory fish. The concentrations of Hg in swordfish, Atlantic bluefin tuna and red mullet accounted for 50%, 30% and 30% of the MLs, respectively. The EWIs for Cd, Pb and Hg related to the consumption

  3. Prestatiekenmerken van de bepaling van As, Cd, Pb en Hg in voeding en biologisch materiaal met ICP-MS en AFS

    NARCIS (Netherlands)

    Velde-Koerts T van der; Bom CM; LAC

    1999-01-01

    Een ICP-MS-methode werd ontwikkeld voor de bepaling van As, Cd en Pb in salpeterzuur-destruaten van voeding en biologisch materiaal. De methode werd