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Sample records for cadmium sulfide quantum

  1. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    OpenAIRE

    Z. O. Lipatova; E. V. Kolobkova; V. A. Aseev

    2015-01-01

    Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been fou...

  2. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    Z. O. Lipatova

    2015-03-01

    Full Text Available Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been found to be dependent on the registration wavelength in the range from 450 to 700 nm. Obtained fluorophosphate glasses with CdS quantum dots can find their application as fluorescent materials with intensive luminescence band and long excited-state natural lifetime.

  3. Luminescent behavior of cadmium sulfide quantum dots for gallic acid estimation.

    Science.gov (United States)

    Singh, Suman; Garg, Sourav; Chahal, Jitender; Raheja, Khushboo; Singh, Deepak; Singla, M L

    2013-03-22

    Thioglycolic acid capped cadmium sulfide (CdS/T) quantum dots have been synthesized using wet chemistry and their optical behavior has been investigated using UV-visible absorption and fluorescence spectroscopy. The role of the capping agent, sulfide source concentration, pH and temperature has been studied and discussed. Studies showed that alkaline pH leads to a decrease in the size of quantum dots and reflux temperature above 70 °C resulted in red-shift of emission spectra which is due to narrowing of the bandgap. Further, to reduce the toxicity and photochemical instability of quantum dots, the quantum dots have been functionalized with polyethylene glycol (PEG), which resulted in a 20% enhancement of the fluorescence intensity. The application potential of CdS/T-PEG quantum dots was further studied using gallic acid as a model compound. The sensing is based on fluorescence quenching of quantum dots in the presence of gallic acid, and this study showed linearity in the range from 1.3 × 10(-8) to 46.5 × 10(-8) mM, with a detection limit of 3.6 × 10(-8) mM.

  4. Luminescent behavior of cadmium sulfide quantum dots for gallic acid estimation

    Science.gov (United States)

    Singh, Suman; Garg, Sourav; Chahal, Jitender; Raheja, Khushboo; Singh, Deepak; Singla, M. L.

    2013-03-01

    Thioglycolic acid capped cadmium sulfide (CdS/T) quantum dots have been synthesized using wet chemistry and their optical behavior has been investigated using UV-visible absorption and fluorescence spectroscopy. The role of the capping agent, sulfide source concentration, pH and temperature has been studied and discussed. Studies showed that alkaline pH leads to a decrease in the size of quantum dots and reflux temperature above 70 °C resulted in red-shift of emission spectra which is due to narrowing of the bandgap. Further, to reduce the toxicity and photochemical instability of quantum dots, the quantum dots have been functionalized with polyethylene glycol (PEG), which resulted in a 20% enhancement of the fluorescence intensity. The application potential of CdS/T-PEG quantum dots was further studied using gallic acid as a model compound. The sensing is based on fluorescence quenching of quantum dots in the presence of gallic acid, and this study showed linearity in the range from 1.3 × 10-8 to 46.5 × 10-8 mM, with a detection limit of 3.6 × 10-8 mM.

  5. Cadmium sulfide quantum dots induce oxidative stress and behavioral impairments in the marine clam Scrobicularia plana.

    Science.gov (United States)

    Buffet, Pierre-Emmanuel; Zalouk-Vergnoux, Aurore; Poirier, Laurence; Lopes, Christelle; Risso-de-Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Perrein-Ettajani, Hanane; Valsami-Jones, Eugenia; Mouneyrac, Catherine

    2015-07-01

    Cadmium sulfide (CdS) quantum dots have a number of current applications in electronics and solar cells and significant future potential in medicine. The aim of the present study was to examine the toxic effects of CdS quantum dots on the marine clam Scrobicularia plana exposed for 14 d to these nanomaterials (10 µg Cd L(-1) ) in natural seawater and to compare them with soluble Cd. Measurement of labile Cd released from CdS quantum dots showed that 52% of CdS quantum dots remained in the nanoparticulate form. Clams accumulated the same levels of Cd regardless of the form in which it was delivered (soluble Cd vs CdS quantum dots). However, significant changes in biochemical responses were observed in clams exposed to CdS quantum dots compared with soluble Cd. Increased activities of catalase and glutathione-S-transferase were significantly higher in clams exposed in seawater to Cd as the nanoparticulate versus the soluble form, suggesting a specific nano effect. The behavior of S. plana in sediment showed impairments of foot movements only in the case of exposure to CdS quantum dots. The results show that oxidative stress and behavior biomarkers are sensitive predictors of CdS quantum dots toxicity in S. plana. Such responses, appearing well before changes might occur at the population level, demonstrate the usefulness of this model species and type of biomarker in the assessment of nanoparticle contamination in estuarine ecosystems.

  6. Charge Carrier Processes in Photovoltaic Materials and Devices: Lead Sulfide Quantum Dots and Cadmium Telluride

    Science.gov (United States)

    Roland, Paul

    Charge separation, transport, and recombination represent fundamental processes for electrons and holes in semiconductor photovoltaic devices. Here, two distinct materials systems, based on lead sulfide quantum dots and on polycrystalline cadmium telluride, are investigated to advance the understanding of their fundamental nature for insights into the material science necessary to improve the technologies. Lead sulfide quantum dots QDs have been of growing interest in photovoltaics, having recently produced devices exceeding 10% conversion efficiency. Carrier transport via hopping through the quantum dot thin films is not only a function of inter-QD distance, but of the QD size and dielectric media of the surrounding materials. By conducting temperature dependent transmission, photoluminescence, and time resolved photoluminescence measurements, we gain insight into photoluminescence quenching and size-dependent carrier transport through QD ensembles. Turning to commercially relevant cadmium telluride (CdTe), we explore the high concentrations of self-compensating defects (donors and acceptors) in polycrystalline thin films via photoluminescence from recombination at defect sites. Low temperature (25 K) photoluminescence measurements of CdTe reveal numerous radiative transitions due to exciton, trap assisted, and donor-acceptor pair recombination events linked with various defect states. Here we explore the difference between films deposited via close space sublimation (CSS) and radio frequency magnetron sputtering, both as-grown and following a cadmium chloride treatment. The as-grown CSS films exhibited a strong donor-acceptor pair transition associated with deep defect states. Constructing photoluminescence spectra as a function of time from time-resolved photoluminescence data, we report on the temporal evolution of this donor-acceptor transition. Having gained insight into the cadmium telluride film quality from low temperature photoluminescence measurements

  7. Circular dichroism sensor based on cadmium sulfide quantum dots for chiral identification and detection of penicillamine

    Energy Technology Data Exchange (ETDEWEB)

    Ngamdee, Kessarin [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 (Thailand); Puangmali, Theerapong [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 (Thailand); Tuntulani, Thawatchai [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330 (Thailand); Ngeontae, Wittaya, E-mail: wittayange@kku.ac.th [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 (Thailand)

    2015-10-22

    A new chemical sensor based on the measuring of circular dichroism signal (CD) was fabricated from cysteamine capped cadmium sulfide quantum dots (Cys-CdS QDs). The chiral-thiol molecules, D-penicillamine (DPA) and L-penicillamine (LPA), were used to evaluate potentials of this sensor. Basically, DPA and LPA provide very low CD signals. However, the CD signals of DPA and LPA can be enhanced in the presence of Cys-CdS QDs. The CD spectra of DPA and LPA exhibited a mirror image profile. Parameters affecting the determination of DPA and LPA were thoroughly investigated in details. Under the optimized condition, the CD signals of DPA and LPA displayed a linear relationship with the concentrations of both enantiomers, ranging from 1 to 35 μM. Detection limits of this sensor were 0.49 and 0.74 μM for DPA and LPA, respectively. To demonstrate a potential application of this sensor, the proposed sensor was used to determine DPA and LPA in real urine samples. It was confirmed that the proposed detection technique was reliable and could be utilized in a broad range of applications. - Highlights: • This paper demonstrates a new CD sensor based on cadmium sulfide quantum dots. • Achiral quantum dots are used for the detection and chiral identification of thiol-chiral containing compounds. • The sensor show highest selectivity towards penicillamine. • The detection limits of the sensor less than 1 μM. • The sensor can potentially be used in physiological urine samples.

  8. Cadmium sulfide quantum dots stabilized by castor oil and ricinoleic acid

    Science.gov (United States)

    Kyobe, Joseph William; Mubofu, Egid Beatus; Makame, Yahya M. M.; Mlowe, Sixberth; Revaprasadu, Neerish

    2016-02-01

    Castor oil and ricinoleic acid (an isolate of castor oil) are environmentally friendly bio-based organic surfactants that have been used as capping agents to prepare nearly spherical cadmium sulfide quantum dots (QDs) at 230, 250 and 280 °C. The prepared quantum dots were characterized by Ultra violet-visible (UV-vis), Photoluminescence (PL), Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM) and X-ray diffraction (XRD) giving an overall CdS QDs average size of 5.14±0.39 nm. The broad XRD pattern and crystal lattice fringes in the HRTEM images showed a hexagonal phase composition of the CdS QDs. The calculated/estimated average size of the prepared castor oil capped CdS QDs for various techniques were 4.64 nm (TEM), 4.65 nm (EMA), 5.35 nm (UV-vis) and 6.46 nm (XRD). For ricinoleic acid capped CdS QDs, the average sizes were 5.56 nm (TEM), 4.78 nm (EMA), 5.52 nm (UV-vis) and 8.21 nm (XRD). Optical properties of CdS QDs showed a change of band gap energy from its bulk band gap of 2.42-2.82 eV due to quantum size confinement effect for temperature range of 230-280 °C. Similarly, a blue shift was observed in the photoluminescence spectra. Scanning electron microscope (SEM) observations show that the as-synthesized CdS QDs structures are spherical in shape. Fourier transform infra-red (FTIR) studies confirms the formation of castor oil and ricinoleic acid capped CdS QDs.

  9. Direct electrochemical stripping detection of cystic-fibrosis-related DNA linked through cadmium sulfide quantum dots

    Science.gov (United States)

    Marin, Sergio; Merkoçi, Arben

    2009-02-01

    Electrochemical detection of a cadmium sulfide quantum dots (CdS QDs)-DNA complex connected to paramagnetic microbeads (MB) was performed without the need for chemical dissolving. The method is based on dropping 20 µl of CdS QD-DNA-MB suspension on the surface of a screen-printed electrode. It is followed by magnetic collection on the surface of the working electrode and electrochemical detection using square-wave voltammetry (SWV), giving a well-shaped and sensitive analytical signal. A cystic-fibrosis-related DNA sequence was sandwiched between the two DNA probes. One DNA probe is linked via biotin-streptavidin bonding with MB and the other one via thiol groups with the CdS QD used as tags. Nonspecific signals of DNA were minimized using a blocking agent and the results obtained were successfully employed in a model DNA sensor with an interest in future applications in the clinical field. The developed nanoparticle biosensing system may offer numerous opportunities in other fields where fast, low cost and efficient detection of small volume samples is required.

  10. Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switches.

    Science.gov (United States)

    Javed, Hina; Fatima, Kalsoom; Akhter, Zareen; Nadeem, Muhammad Arif; Siddiq, Muhammad; Iqbal, Azhar

    2016-02-01

    We have investigated the attachment of azobenzene photochromic switches on the modified surface of cadmium sulfide (CdS) quantum dots (QDs). The modification of CdS QDs is done by varying the concentration of the capping agent (mercaptoacetic acid) and NH3 in order to control the size of the QDs. The X-ray diffraction studies revealed that the crystallite size of CdS QDs ranged from 6 to 10 nm. The azobenzene photochromic derivatives bis(4-hydroxybenzene-1-azo)4,4'(1,1' diphenylmethane) (I) and 4,4'-diazenyldibenzoic acid (II) were synthesized and attached with surface-modified CdS QDs to make fluorophore-photochrome CdS-(I) and CdS-(II) dyad assemblies. Upon UV irradiation, the photochromic compounds (I) and (II) undergo a reversible trans-cis isomerization. The photo-induced trans-cis transformation helps to transfer photo-excited electrons from the conduction band of the CdS QDs to the lowest unoccupied molecular orbital of cis isomer of photochromic compounds (I) and (II). As a result, the fluorescence of CdS-(I) and CdS-(II) dyads is suppressed approximately five times compared to bare CdS QDs. The fluorescence modulation in such systems could help to design luminescent probes for bioimaging applications.

  11. Lossless synthesis of graphene nanosheets decorated with tiny cadmium sulfide quantum dots with excellent nonlinear optical properties.

    Science.gov (United States)

    Feng, Miao; Sun, Ruiqing; Zhan, Hongbing; Chen, Yu

    2010-02-19

    The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended pi conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the pi-pi stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.

  12. A circular dichroism sensor for Ni(2+) and Co(2+) based on L-cysteine capped cadmium sulfide quantum dots.

    Science.gov (United States)

    Tedsana, Wimonsiri; Tuntulani, Thawatchai; Ngeontae, Wittaya

    2015-03-31

    A new circular dichroism sensor for detecting Ni(2+) and Co(2+) was proposed for the first time using chiral chelating quantum dots. The detection principle was based on changing of circular dichroism signals of the chiral quantum dots when forming a chiral complex with Ni(2+) or Co(2+). L-Cysteine capped cadmium sulfide quantum dots (L-Cyst-CdS QDs) were proposed as a chiral probe. The CD spectrum of L-Cyst-CdS QDs was significantly changed in the presence of Ni(2+) and Co(2+). On the other hand, other studied cations did not alter the original CD spectrum. Moreover, when increasing the concentration of Ni(2+) or Co(2+), the intensity of the CD spectrum linearly increased as a function of concentration and could be useful for the quantitative analysis. The proposed CD sensor showed linear working concentration ranges of 10-60 μM and 4-80 μM with low detection limits of 7.33 μМ and 1.13 μM for the detection of Ni(2+) and Co(2+), respectively. Parameters possibly affected the detection sensitivity such as solution pH and incubation time were studied and optimized. The proposed sensor was applied to detect Ni(2+) and Co(2+) in real water samples, and the results agreed well with the analysis using the standard ICP-OES.

  13. The proteomic response of Arabidopsis thaliana to cadmium sulfide quantum dots, and its correlation with the transcriptomic response

    Directory of Open Access Journals (Sweden)

    Marta eMarmiroli

    2015-12-01

    Full Text Available A fuller understanding of the interaction between plants and engineered nanomaterials is of topical relevance because the latter are beginning to find applications in agriculture and the food industry. There is a growing need to establish objective safety criteria for their use. The recognition of two independent Arabidopsis thaliana mutants displaying a greater level of tolerance than the wild type plant to exposure to cadmium sulfide quantum dots (CdS QDs has offered the opportunity to characterize the tolerance response at the physiological, transcriptomic and proteomic levels. Here, a proteomics-based comparison confirmed the conclusions drawn from an earlier transcriptomic analysis that the two mutants responded to CdS QD exposure differently both to the wild type and to each other. Just over half of the proteomic changes mirrored documented changes at the level of gene transcription, but a substantial number of transcript/gene product pairs were altered in the opposite direction. An interpretation of the discrepancies is given, along with some considerations regarding the use and significance of -omics when monitoring the potential toxicity of ENMs for health and environment.

  14. Facile covalent immobilization of cadmium sulfide quantum dots on graphene oxide nanosheets: preparation, characterization, and optical properties

    Science.gov (United States)

    Pham, Tuan Anh; Choi, Byung Choon; Jeong, Yeon Tae

    2010-11-01

    A facile approach for the preparation of a novel hybrid material containing graphene and an inorganic semiconducting material, cadmium sulfide quantum dots (CdS QDs), is demonstrated for the first time. First, amino-functionalized CdS QDs were prepared by modifications of the kinetic trapping method. Then, pristine graphite was oxidized and exfoliated to obtain graphene oxide nanosheets (GONS), which were then acylated with thionyl chloride to introduce acyl chloride groups on their surface. Subsequently, immobilization of the CdS QDs on the GONS surface was achieved through an amidation reaction between the amino groups located on the CdS QDs surface and the acyl chloride groups bound to the GONS surface. Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H-NMR), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and energy dispersive x-ray (EDX) spectroscopy were employed to investigate the changes in the surface functionalities, while high resolution transmission electron microscopy (HR-TEM) and field emission scanning electronic microscopy (FE-SEM) were used to study the morphologies and distribution of the CdS QDs on the GONS surface. Thermogravimetric analysis (TGA) was employed to characterize the weight loss of the samples on heating. Photoluminescence (PL) measurements were used to study the optical properties of the prepared CdS QDs and the CdS-graphene hybrid material.

  15. Improvement of the luminescent properties of cadmium sulfide quantum dots by a post-synthesis modification

    Energy Technology Data Exchange (ETDEWEB)

    López, Israel; Gómez, Idalia, E-mail: maria.gomezd@uanl.edu.mx

    2014-11-15

    Here the improvement of the luminescent properties of CdS quantum dots by a post-synthesis modification with aqueous solutions of NaOH at different concentrations is presented. The CdS quantum dots were synthesized by a microwave-assisted method using citrate ions as stabilizer. The addition of the hydroxide ions increased the intensity of the orange-red emission by about 80%. Besides, a violet-blue emission was achieved by means of this post-synthesis modification. The hydroxide ions control the precipitation equilibria of the CdS and Cd(OH){sub 2}, dissolving and precipitating the surface of the quantum dots. The NaOH treatment increases the number of traps, which produces less band-edge and more deep-trap emission, which explains the decrease and increase in the intensity of the violet-blue and orange-red emissions, respectively.

  16. A bifacial quantum dot-sensitized solar cell with all-cadmium sulfide photoanode

    Science.gov (United States)

    Ma, Chunqing; Tang, Qunwei; Liu, Danyang; Zhao, Zhiyuan; He, Benlin; Chen, Haiyan; Yu, Liangmin

    2015-02-01

    Pursuit of a high power conversion efficiency and reduction of electricity-generation cost has been a persistent objective for quantum dot-sensitized solar cells (QDSSCs). We present here the fabrication of a QDSSC comprising a nanoflower-structured CdS anode, a liquid electrolyte having S2-/Sn2- redox couples, and a transparent CoSe counter electrode. Nanoflower-structured CdS anodes are prepared by a successive ionic layer adsorption and reaction (SILAR) method and subsequently hydrothermal strategy free of any surfactant or template. The CdS nanoparticles synthesized by a SILAR method act as "seed crystal" for growth of CdS nanoflowers. The average electron lifetime is markedly elevated in nanoflower-structured CdS anode in comparison with CdS nanoparticle or nanoporous CdS microsphere anode. Herein, we study the effect of synthesis method on CdS morphology and solar cell's photovoltaic performance, showing a power conversion efficiency of 1.67% and 1.17% for nanoflower-structured CdS QDSSC under front and rear irradiations, respectively.

  17. Preparation, theory, and biological applications of highly luminescent cadmium selenide/zinc sulfide quantum dots in optical and electron microscopy

    Science.gov (United States)

    Bouwer, James Christopher

    This dissertation describes the preparation, theory, and applications of ZnS overcoated CdSe (core) quantum dots for applications as fluorescent probes in optical microscopy and as electron energy loss spectroscopy (EELS) probes in electron microscopy, with applications to the biological sciences. The dissertation begins with a brief overview of quantum dots and their history. Next, a brief overview of the necessary semiconductor theory is discussed including the origin of the band gap, the origin of holes, the concepts of phonons, and trap states. Then, the role of the confinement potential in the quantum dot fluorescent spectrum is discussed in the context of the 3-dimensional spherical well. Included in this discussion is the role of excitonic electron-hole bound states. To provide a complete document useful to anyone who wishes to continue work along these lines, included is a methods section which describes the complete process of synthesis of the CdSe cores, overcoating the cores with ZnS, size selection of nanocrystals, water solubilization, and protein conjugation. The methods used in live cell labeling are included as well. In the section that follows, a discussion of the mathematical methods of image correlation spectroscopy (ICS) for extracting dynamic constants such as flow rates and diffusion constants from time lapse optical image data is discussed in the context of quantum dot fluorescent probes. Dynamic constants were obtained using live NIH3T3 mouse fibroblast cells labeled with IgG-anti-EGF conjugated quantum dots. These same cells were then fixed, imbedded in resin, sectioned to 100nm thick sections and imaged under the electron microscope. The electron dense cadmium selinide provides the contrast necessary to perform direct imaging of EGF receptor sites. In order to improve the data and move toward multi-channel imaging in the electron microscope, EELS spectroscopy and elemental mapping of quantum dots was performed. The theory along with a

  18. INVESTIGATION OF THIN FILM CADMIUM SULFIDE SOLAR CELLS.

    Science.gov (United States)

    SOLAR CELLS , *CADMIUM COMPOUNDS, FILMS, SULFIDES, VAPOR PLATING, VACUUM APPARATUS, SINGLE CRYSTALS, TITANIUM, COPPER COMPOUNDS, CHLORIDES, INDIUM, MOLYBDENUM, SILICON COMPOUNDS, MONOXIDES, SURFACE PROPERTIES, ENERGY CONVERSION.

  19. A circular dichroism sensor for Ni{sup 2+} and Co{sup 2+} based on L-cysteine capped cadmium sulfide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tedsana, Wimonsiri [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Tuntulani, Thawatchai [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ngeontae, Wittaya, E-mail: wittayange@kku.ac.th [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2015-03-31

    Highlights: • Demonstrated a new efficient sensor platform based quantum dots. • Used chiral quantum dots as CD sensor for the detection of heavy metal ions for the first time. • The proposed CD sensor showed highest selectivity towards Ni{sup 2+} and Co{sup 2+}. • Low detection limits of 7.33 μM and 1.13 μM for Ni{sup 2+} and Co{sup 2+}, respectively. • Can be used in real water samples comparing with ICP-OES. - Abstract: A new circular dichroism sensor for detecting Ni{sup 2+} and Co{sup 2+} was proposed for the first time using chiral chelating quantum dots. The detection principle was based on changing of circular dichroism signals of the chiral quantum dots when forming a chiral complex with Ni{sup 2+} or Co{sup 2+}. L-Cysteine capped cadmium sulfide quantum dots (L-Cyst-CdS QDs) were proposed as a chiral probe. The CD spectrum of L-Cyst-CdS QDs was significantly changed in the presence of Ni{sup 2+} and Co{sup 2+}. On the other hand, other studied cations did not alter the original CD spectrum. Moreover, when increasing the concentration of Ni{sup 2+} or Co{sup 2+}, the intensity of the CD spectrum linearly increased as a function of concentration and could be useful for the quantitative analysis. The proposed CD sensor showed linear working concentration ranges of 10–60 μM and 4–80 μM with low detection limits of 7.33 μM and 1.13 μM for the detection of Ni{sup 2+} and Co{sup 2+}, respectively. Parameters possibly affected the detection sensitivity such as solution pH and incubation time were studied and optimized. The proposed sensor was applied to detect Ni{sup 2+} and Co{sup 2+} in real water samples, and the results agreed well with the analysis using the standard ICP-OES.

  20. Cobalt-doped cadmium sulfide nanoparticles as efficient strategy to enhance performance of quantum dot sensitized solar cells

    Science.gov (United States)

    Firoozi, Najmeh; Dehghani, Hossein; Afrooz, Malihe

    2015-03-01

    In this study, we investigate the effect of Co2+ ion incorporation into CdS layer on the photovoltaic performance of quantum dot sensitized solar cell (QDSSC). Quantum dots are deposited by the successive ionic layer adsorption and reaction (SILAR) method on the mesoporous TiO2 film. The doped system modifies the structure of photoanode that leads to an increase in short circuit current density (Jsc) from 13.16 mA cm-2 to 16.6 mA cm-2 in the un-doped system. Electrochemical impedance analysis (EIS) reveals a decrease in charge transfer resistance at the TiO2/QDs/electrolyte interface that arises from the presence of an internal recombination pathway. The highest energy conversion efficiency (η) of 3.16% is obtained under standard air mass 1.5 global (AM 1.5G) simulated sun light by doping the optimized amount of Co2+ ion in CdS nanoparticles, corresponding to efficiency increment (35%) compared to the un-doped system. The origin of the increase in the efficiency is attributed to the dominance of charge collection to recombination. To further investigation of the electron transport time in the photoanode, the intensity modulated photocurrent spectroscopy (IMPS) is performed under standard conditions. Our obtained results can help to develop a simple and effective method to enhance the efficiency in the QDSSCs.

  1. Photocatalytic hydrogen evolution from glycerol and water over nickel-hybrid cadmium sulfide quantum dots under visible-light irradiation.

    Science.gov (United States)

    Wang, Jiu-Ju; Li, Zhi-Jun; Li, Xu-Bing; Fan, Xiang-Bing; Meng, Qing-Yuan; Yu, Shan; Li, Cheng-Bo; Li, Jia-Xin; Tung, Chen-Ho; Wu, Li-Zhu

    2014-05-01

    Natural photosynthesis offers the concept of storing sunlight in chemical form as hydrogen (H2), using biomass and water. Herein we describe a robust artificial photocatalyst, nickel-hybrid CdS quantum dots (Nih-CdS QDs) made in situ from nickel salts and CdS QDs stabilized by 3-mercaptopropionic acid, for visible-light-driven H2 evolution from glycerol and water. With visible light irradiation for 20 h, 403.2 μmol of H2 was obtained with a high H2 evolution rate of approximately 74.6 μmol h(-1)  mg(-1) and a high turnover number of 38 405 compared to MPA-CdS QDs (mercaptopropionic-acid-stabilized CdS quantum dots). Compared to CdTe QDs and CdSe QDs, the modified CdS QDs show the greatest affinity toward Ni(2+) ions and the highest activity for H2 evolution. X-ray photoelectron spectroscopy (XPS), inductively-coupled plasma atomic emission spectrometry (ICP-AES), and photophysical studies reveal the chemical nature of the Nih-CdS QDs. Electron paramagnetic resonance (EPR) and terephthalate fluorescence measurements clearly demonstrate water splitting to generate ⋅OH radicals. The detection of DMPO-H and DMPO-C radicals adduct in EPR also indicate that ⋅H radicals and ⋅C radicals are the active species in the catalytic cycle.

  2. Cadmium sulfide quantum dots supported on gallium and indium oxide for visible-light-driven hydrogen evolution from water.

    Science.gov (United States)

    Pan, Yun-xiang; Zhuang, Huaqiang; Hong, Jindui; Fang, Zheng; Liu, Hai; Liu, Bin; Huang, Yizhong; Xu, Rong

    2014-09-01

    In this work, CdS quantum dots (QDs) supported on Ga2O3 and In2O3 are applied for visible-light-driven H2 evolution from aqueous solutions that contain lactic acid. With Pt as the cocatalyst, the H2 evolution rates on CdS/Pt/Ga2O3 and CdS/Pt/In2O3 are as high as 995.8 and 1032.2 μmol h(-1), respectively, under visible light (λ>420 nm) with apparent quantum efficiencies of 43.6 and 45.3% obtained at 460 nm, respectively. These are much higher than those on Pt/CdS (108.09 μmol h(-1)), Pt/Ga2O3 (0.12 μmol h(-1)), and Pt/In2O3 (0.05 μmol h(-1)). The photocatalysts have been characterized thoroughly and their band structures and photocurrent responses have been measured. The band alignment between the CdS QDs and In2O3 can lead to interfacial charge separation, which cannot occur between the CdS QDs and Ga2O3. Among the various possible factors that contribute to the high H2 evolution rates on CdS/Pt/oxide, the surface properties of the metal oxides play important roles, which include (i) the anchoring of CdS QDs and Pt nanoparticles for favorable interactions and (ii) the efficient trapping of photogenerated electrons from the CdS QDs because of surface defects (such as oxygen defects) based on photoluminescence and photocurrent studies.

  3. A study of the stability of cadmium sulfide/copper sulfide and cadmium sulfide copper-indium-diselenide solar cells

    Science.gov (United States)

    Noel, G.; Richard, N.; Gaines, G.

    1984-08-01

    Groups of high efficiency cadmium sulfide/copper sulfide solar cells were exposed to combinations of stresses designed to isolate and accelerate intrinsic degradation mechanisms. Stresses included elevated temperature, illumination intensity, and cell loading conditions. All stress exposures and tests were conducted in a benign (high purity argon) atmosphere. Two primary intrinsic modes of degradation were identified: degradation of the open circuit voltage under continuous illumination and nonzero loading was found to be self recovering upon interruption of illumination or upon shorting or reverse biasing the cells. It was attributed to traps in the depletion region. Recovery from decay of light generated current was not spontaneous but could be partially accomplished by annealing in a reducing (hydrogen) environment. It was attributed to changes in the stoichiometry of the copper sulfide under the influence of electric fields and currents.

  4. Dual-channel optical sensing platform for detection of diminazene aceturate based on thioglycolic acid-wrapped cadmium telluride/cadmium sulfide quantum dots.

    Science.gov (United States)

    Hao, Chenxia; Zhou, Tao; Liu, Shaopu; Wang, Linlin; Huang, Bowen; Kuang, Nianxi; He, Youqiu

    2016-06-15

    A dual-channel optical sensing platform which combines the advantages of dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) and fluorescence has been designed for the detection of diminazene aceturate (DA). It is based on the use of thioglycolic acid-wrapped CdTe/CdS quantum dots (Q-dots). In the absence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots exhibit the high fluorescence spectrum and low RRS spectrum, so are selected to develop an easy-to-get system. In the presence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots and DA form a complex through electrostatic interaction, which result in the RRS intensity getting enhanced significantly with new RRS peaks appearing at 317 and 397 nm; the fluorescence is powerfully quenched. Under optimum conditions, the scattering intensities of the two peaks are proportional to the concentration of DA in the range of 0.0061-3.0 μg mL(-1). The detection limits for the two single peaks are 4.1 ng mL(-1) and 3.3 ng mL(-1), while that of the DWO-RRS method is 1.8 ng mL(-1), indicating that the DWO-RRS method has high sensitivity. Besides, the fluorescence also exhibits good linear range from 0.0354 to 10.0 μg mL(-1) with a detection limit of 10.6 ng mL(-1). In addition, the system has been applied to the detection of DA in milk samples with satisfactory results.

  5. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  6. Photoluminescence spectral study of single cadmium selenide/zinc sulfide colloidal nanocrystals in poly(methyl methacrylate) and quantum dots molecules

    Science.gov (United States)

    Shen, Yaoming

    Quantum dots (QDs)and Nano-crystals (NCs) have been studies for decades. Because of the nanoscale quantum confinement, delta shape like energy density states and narrowband emitters properties, they hold great promise for numerous optoelectronics and photonics applications. They could be used for tunable lasers, white LED, Nano-OLED, non-volatile memory and solar cells. They are also the most promising candidates for the quantum computing. The benefits for NCs over QDs is that NCs can be incorporated into a variety of polymers as well as thin films of bulk semiconductors. These exceptional flexibility and structural control distinguish NCs from the more traditional QD structures fabricated using epitaxial growth techniques. In my research of work, I studied the photoluminescence (PL) and absorption character of ensemble NCs incorporated in Polymethyl methacrylate (PMMA). To understand the behavior of the NCs in PMMA, it is important to measure a singe NC to avoid the inhomogenous broading of many NCs. So I particularly studied the behavior of a single NC in PMMA matrix. A microphotoluminescence setup to optically isolate a single nanocrystal is used. Random spectral shift and blinking behavior (on and off) are found. Addition to that, two color spectral shifting, is a major phenomena found in the system. Other interesting results such as PL intensity changes (decreasing or increasing with time) and quenching effect are observed and explained too. From the correlation function, we can distinguish the phonon replicas. The energy of these phonons can be calculated very accurately from the experiment result. The Huang-Rhys factors can be estimated too. Self-assembled semiconductor quantum dots (QDs), from highly strained-layer heteroepitaxy in the Stranski-Krastanow (S-K) growth mode, have been intensively studied because of the delta-function-like density of states, which is significant for optoelectronic applications. Spontaneous formation of semiconductor quantum

  7. In situ synthesis of binary cobalt-ruthenium nanofiber alloy counter electrode for electrolyte-free cadmium sulfide quantum dot solar cells

    Science.gov (United States)

    Du, Nan; Ren, Lei; Sun, Weifu; Jin, Xiao; Zhao, Qing; Cheng, Yuanyuan; Wei, Taihuei; Li, Qinghua

    2015-06-01

    A facile, low-cost and low-temperature fabrication approach of counter electrode is essential for pursuing robust photovoltaic devices. Herein, we develop a hydrothermal in situ growth of Cobalt-Ruthenium (Co-Ru) alloy nanofiber electrode for quantum dot solar cell (QDSC) applications. Colloidal CdS QDs with tunable absorption band edge are synthesized and used as light absorber. After optimizing the QDs with the highest photoluminescence quantum yield accompanied by considerable solar light absorption ability, QDSC based on Co-Ru alloy electrode delivers a much higher power conversion efficiency than its counterparts, i.e., either pure Co or Ru metal electrodes. In detail, Co-Ru alloy electrode exhibits high specific area, excellent electrical behavior, intimate interface contact, and good stability, thus leading to notable improved device performances. The impressive robust function of Co-Ru alloy with simple manufacturing procedure highlights its potential applications in robust QDSCs.

  8. Morphological variations in cadmium sulfide nanocrystals without phase transformation

    Directory of Open Access Journals (Sweden)

    Colorado Henry

    2011-01-01

    Full Text Available Abstract A very novel phenomenon of morphological variations of cadmium sulfide (CdS nanorods under the transmission electron microscopy (TEM beam was observed without structural phase transformation. Environmentally stable and highly crystalline CdS nanorods have been obtained via a chemical bath method. The energy of the TEM beam is believed to have a significant influence on CdS nanorods and may melt and transform them into smaller nanowires. Morphological variations without structural phase transformation are confirmed by recording selected area electron diffraction at various stages. The prepared CdS nanorods have been characterized by X-ray powder diffraction, TEM, UV-Vis spectroscopy, and photoluminescence spectroscopy. The importance of this phenomenon is vital for the potential application for CdS such as smart materials.

  9. An ultrasensitive and selective method for the determination of Ceftriaxone using cysteine capped cadmium sulfide fluorescence quenched quantum dots as fluorescence probes

    Science.gov (United States)

    Samadi, Naser; Narimani, Saeedeh

    2016-06-01

    In this paper, L-cysteine (Cys) coated CdS quantum dots (QDs) have been prepared, which have excellent water-solubility and are highly stable in aqueous solution. These QDs is proposed as sensitizers for the determination of Ceftriaxone. The quantum dot nanoparticles were structurally and optically characterized by Ultra Violet-Visible absorption Spectroscopy (UV-vis absorption spectroscopy), Fourier transform infrared spectroscopy (FT-IR spectra) and photoluminescence (PL) emission spectroscopy. High resolution transmission electron microscopy (HRTEM) confirms that the Cys-CdS QDs have a spherical structure with good crystallinity. Therefore, a new simple and selective PL analysis system was developed for the determination of Ceftriaxone (CFX). Under the optimum conditions, The response of L-Cys capped CdS QDs as the probe was linearly proportional to the concentration of Ceftriaxone ions in the range of 1.6 × 10- 9-1.1 × 10- 3 M with a correlation coefficient (R2) of 0.9902. The limit of detection of this system was found to be 1.3 nM. This method is simple, sensitive and low cost.

  10. An ultrasensitive and selective method for the determination of Ceftriaxone using cysteine capped cadmium sulfide fluorescence quenched quantum dots as fluorescence probes.

    Science.gov (United States)

    Samadi, Naser; Narimani, Saeedeh

    2016-06-15

    In this paper, l-cysteine (Cys) coated CdS quantum dots (QDs) have been prepared, which have excellent water-solubility and are highly stable in aqueous solution. These QDs is proposed as sensitizers for the determination of Ceftriaxone. The quantum dot nanoparticles were structurally and optically characterized by Ultra Violet-Visible absorption Spectroscopy (UV-vis absorption spectroscopy), Fourier transform infrared spectroscopy (FT-IR spectra) and photoluminescence (PL) emission spectroscopy. High resolution transmission electron microscopy (HRTEM) confirms that the Cys-CdS QDs have a spherical structure with good crystallinity. Therefore, a new simple and selective PL analysis system was developed for the determination of Ceftriaxone (CFX). Under the optimum conditions, The response of l-Cys capped CdS QDs as the probe was linearly proportional to the concentration of Ceftriaxone ions in the range of 1.6×10(-9)-1.1×10(-3)M with a correlation coefficient (R2) of 0.9902. The limit of detection of this system was found to be 1.3nM. This method is simple, sensitive and low cost.

  11. Cadmium telluride quantum dots advances and applications

    CERN Document Server

    Donegan, John

    2013-01-01

    Optical Properties of Bulk and Nanocrystalline Cadmium Telluride, Núñez Fernández and M.I. VasilevskiyAqueous Synthesis of Colloidal CdTe Nanocrystals, V. Lesnyak, N. Gaponik, and A. EychmüllerAssemblies of Thiol-Capped CdTe Nanocrystals, N. GaponikFörster Resonant Energy Transfer in CdTe Nanocrystal Quantum Dot Structures, M. Lunz and A.L. BradleyEmission of CdTe Nanocrystals Coupled to Microcavities, Y.P. Rakovich and J.F. DoneganBiological Applications of Cadmium Telluride Semiconductor Quantum Dots, A. Le Cign

  12. Cadmium sulfide thin films deposited by close spaced sublimation and cadmium sulfide/cadmium telluride solar cells

    Science.gov (United States)

    Marinskiy, Dmitriy Nikolaevich

    1998-12-01

    been characterized by light and dark current-voltage (I-V) measurements. Based on the I-V results samples were selected for Quantum Efficiency (QE), and I-V-T measurements. The goal of this project was to understand what properties of CdS are important for the formation of a good electrical CdS/CdTe junction and high efficiency solar cells. It was found that passivation of the CdS/CdTe interface is essential to obtain efficient devices. The passivation can be achieved by promoting mixing at the interface or by performing a heat treatment of the CdS surface prior to the CdTe deposition. For the latter case no noticeable intermixing at the CdS/CdTe interface occurs. Therefore, it is suggested that the CdS/CdTe interface is the most critical part of the device and the condition of the CdS surface just before CdTe deposition is one of the factors controlling its formation. To date, the best device has shown an efficiency of 15.1% as verified at the National Renewable Energy Laboratory. It is the highest efficiency reported for an all CSS fabricated solar cell. The best all CSS device fabricated on LOF glass substrate demonstrated an efficiency of 14.3%, which is a new record for the USF solar cell laboratory.

  13. Embedding of colloidal Cadmium sulfide nanoparticles into poly-methylmetacrylate matrix

    OpenAIRE

    M. Bissengaliyeva; M. Zhukush; Irina Irgibayeva

    2012-01-01

    The technique of synthesis of polymethylmethacrylate – cadmium sulfide nanocomposites involving precipitation of CdS nanoparticles from polymethylmethacrylate solution in methylmethacrylate monomer with its subsequent polymerization is presented. A difference between the spectral-luminescent properties of the surface composite layer and the nanomaterial bulk, connected with redistribution of particles with higher degree of imperfection closer to the surface during polymerization is revealed.

  14. Inhibition of sulfate reduction by iron, cadmium and sulfide in granular sludge

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Silva, Blanca M. [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a. Seccion, 78216, San Luis Potosi, S.L.P. (Mexico); Briones-Gallardo, Roberto [Facultad de Ingenieria-Instituto de Metalurgia, Universidad Autonoma de San Luis Potosi, Sierra Leona 550, Lomas 2a. Seccion, 78210, San Luis Potosi, S.L.P. (Mexico); Razo-Flores, Elias [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a. Seccion, 78216, San Luis Potosi, S.L.P. (Mexico); Celis, Lourdes B., E-mail: celis@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a. Seccion, 78216, San Luis Potosi, S.L.P. (Mexico)

    2009-12-15

    This study investigated the inhibition effect of iron, cadmium and sulfide on the substrate utilization rate of sulfate reducing granular sludge. A series of batch experiments in a UASB reactor were conducted with different concentrations of iron (Fe{sup 2+}, 4.0-8.5 mM), cadmium (Cd{sup 2+}, 0.53-3.0 mM) and sulfide (4.2-10.6 mM), the reactor was fed with ethanol at 1 g chemical oxygen demand (COD)/L and sulfate to yield a COD/SO{sub 4}{sup 2-} (g/g) ratio of 0.5. The addition of iron, up to a concentration of 8.1 mM, had a positive effect on the substrate utilization rate which increased 40% compared to the rate obtained without metal addition (0.25 g COD/g VSS-d). Nonetheless, iron concentration of 8.5 mM inhibited the specific substrate utilization rate by 57% compared to the substrate utilization rate obtained in the batch amended with 4.0 mM Fe{sup 2+} (0.44 g COD/g VSS-d). Cadmium had a negative effect on the specific substrate utilization rate at the concentrations tested; at 3.0 mM Cd{sup 2+} the substrate utilization rate was inhibited by 44% compared with the substrate utilization rate without metal addition. Cadmium precipitation with sulfide did not decrease the inhibition of cadmium on sulfate reduction. These results could have important practical implications mainly when considering the application of the sulfate reducing process to treat effluents with high concentrations of sulfate and dissolved metals such as iron and cadmium.

  15. Photocatalytic Activity of Nanosized Cadmium Sulfides Synthesized by Complex Compound Thermolysis

    Directory of Open Access Journals (Sweden)

    Yingchun Yu

    2011-01-01

    Full Text Available The nanosized cadmium sulfides (CdSs containing different phase structures were synthesized via the complex compound thermolysis method using different molar ratio of thiourea to acetate cadmium (S/Cd and characterized by XRD, TEM, UV-Vis, and IR spectra. The results of photocatalytic degradation of rhodamine B (RB show that the activity order of CdS concerning the phase compositions is of cubic > hexagonal > cubic + hexagonal, where the CdS with the cubic phase has the best photocatalytic degradation activity of RB due to its larger abilities of adsorption and absorbance and smaller particle size of about 10∼13 nm.

  16. Aqueous synthesis and characterization of bovine hemoglobin-conjugated cadmium sulfide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangrui [Institute of Environmental and Municipal Engineering, North China University of Water Conservancy and Electric Power, Zhengzhou 450011 (China); Qin, Dezhi, E-mail: dezhiqin@163.com [College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan 467000 (China); Du, Xian; Zhang, Li; Zhao, Ganqing; Zhang, Qiuxia; Wu, Jiulin [College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan 467000 (China)

    2014-08-01

    Highlights: • CdS nanocrystals were synthesized by biomimetic method in bovine hemoglobin (BHb) solution. • The study of the interaction between Cd{sup 2+}/CdS and BHb. • The optical properties of BHb-conjugated CdS nanocrystals. • The synthesis process of BHb-conjugated CdS nanocrystals is facile, effective and environment friendly. • The change of secondary structure of BHb after binding to CdS nanocrystals. - Abstract: Cadmium sulfide (CdS) nanocrystals with average diameter about 5.5 nm were synthesized in aqueous solution of bovine hemoglobin (BHb) via simple biomimetic method. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) characterizations were used to determine the structure and morphology of CdS nanocrystals. It was revealed that amount of BHb, chelating of Cd{sup 2+} to BHb and reaction temperature were key factors in controlling shape and dispersion of CdS nanocrystals. The binding sites of BHb to CdS nanocrystals and the change of secondary structure of protein have been identified by Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy. It was found that conjugating of BHb with Cd{sup 2+} and CdS could protect nanocrystals from agglomerating. Moreover, the thermostability of BHb enhanced after conjugating with CdS nanocrystals. The interaction mechanism of BHb with Cd{sup 2+}/CdS was also proposed. The quantum-confined effect of CdS nanocrystals was confirmed by ultraviolet–visible (UV–vis) spectrum. The nanocrystals exhibited a well-defined photoluminescence (PL) emission feature at about 510 nm with narrow full width at half maximum (FWHM)

  17. Synthesis and Characterization of Cadmium Sulfide Nanoparticles by Chemical Precipitation Method.

    Science.gov (United States)

    Devi, R Aruna; Latha, M; Velumani, S; Oza, Goldie; Reyes-Figueroa, P; Rohini, M; Becerril-Juarez, I G; Lee, Jae-Hyeong; Yi, Junsin

    2015-11-01

    Cadmium sulfide (CdS) nanoparticles were synthesized by chemical precipitation method using cadmium chloride (CdCl2), sodium sulfide (Na2S) and water as a solvent by varying temperatures from 20-80 degrees C. The nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), High-resolution transmission electron microscopy (HR-TEM) and UV-Visible spectroscopy. XRD pattern revealed cubic crystal structure for all the synthesized CdS nanoparticles. Raman spectra showed first and second order longitudinal optical (LO) phonon vibrational modes of CdS. The size of CdS nanoparticles was found to be in the range of 15-80 nm by FE-SEM analysis, in all cases. The atomic percentage of cadmium and sulfur was confirmed to be 1:1 from EDS analysis. TEM micrograph depicts the spherical shape of the particles and the size is in the range of 15-85 nm while HR-TEM images of CdS nanoparticles exhibit well-resolved lattice fringes of the cubic structure of CdS. The optical properties of CdS were examined by UV-Visible spectroscopy which showed variation in absorption band from 460-480 nm. The band gap was calculated from the absorption edge and found to be in the range of 3.2-3.5 eV which is greater than the bulk CdS.

  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. Resonant photoactivation of cadmium sulfide and its effect on the surface chemical activity

    Science.gov (United States)

    Giberti, Alessio; Fabbri, Barbara; Gaiardo, Andrea; Guidi, Vincenzo; Malagù, Cesare

    2014-06-01

    Photo-enhanced surface chemical activity of cadmium sulfide gives rise to a wide class of surface-dependent phenomena, such as heterogeneous photocatalysis, chemoresistivity, and chemiluminescence, which have several technological and scientific applications. In this work, the photochemical properties of nanostructured cadmium sulfide films are investigated by means of electrical conductance measurements in controlled atmosphere, while irradiated by light of wavelengths ranging from 400 to 645 nm. Chemisorption of benzene, carbon monoxide, methane, ethanol, and hydrogen sulfide onto CdS surface has been analyzed as a function of the wavelength, in a gas concentration range of the order of parts per million. It resulted that the increase of photoconductance with gas adsorption is resonant with the bandgap energy. It turns out that this resonant enhancement of the surface chemical activity can be of advantage for all the optical and chemical mechanisms that depend upon it. An interpretation of these results, in terms of electronic optical transitions and Fermi level shift induced by light, is proposed.

  20. Synthesis and Characterization of Cadmium Sulfide Nanoparticles via a Simple Thermal Decompose Method

    Science.gov (United States)

    Seyghalkar, Hamideh; Sabet, Mohammad; Salavati-Niasari, Masoud

    2016-11-01

    In this work, cadmium sulfide (CdS) nanoparticles were synthesized from a new Cd-octanoate complex via a simple thermal decompose method. The crystallinity of the product was obtained from X-ray diffraction (XRD) pattern. The morphology and product size were analyzed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also Fourier transform infrared (FT-IR) spectroscopy was used to investigate the CdS surface purity. Finally, the optical properties of the product were obtained from photoluminescence (PL) spectroscopy.

  1. Well-dispersed cadmium sulfide prepared in the presence of laponite by microwave irradiation

    Science.gov (United States)

    Han, Zhaohui; Yang, Qing; Shi, Jeffrey; Lu, G. Q.; Lewis, Simon W.

    2008-05-01

    The reactions of cadmium chloride and various sulfur sources in the suspension of laponite produced CdS nanoparticles. Laponite was used to help keep good dispersion of the sulfide particles and it also facilitated the formation of the product by providing a basic environment when carbon disulfide was used as a source of sulfur in the reaction. The amount of laponite used in the preparation, heating rate and reaction temperature were tested for their effect on result. Different sulfur source materials were used for the preparation, and reactions involved in the preparation were discussed. The varied reaction conditions produced CdS particles with varied shape and size, and in good dispersion.

  2. The Influence of Technological Modes on the Physical Properties of Cadmium Sulfide Nanocrystals Derived by the Electrolyte Method

    Directory of Open Access Journals (Sweden)

    N.B. Danilevska

    2016-06-01

    Full Text Available The effect of concentration of sodium thiosulfate and the temperature of the electrolyte in the process of obtaining cadmium sulfide nanocrystals electrolyte method using cadmium electrodes. X-ray diffraction studies were used to determine the size of the nanocrystals using the Debye-Scherrer formula and method of Williamson-Hall. Comparison of the results of XRD studies the results of Raman spectroscopy and differential thermal analysis.

  3. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Energy Technology Data Exchange (ETDEWEB)

    Osuntokun, Jejenija; Ajibade, Peter A., E-mail: pajibade@ufh.ac.za

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato–κS,S’–bis (N,N-dimethylthiourea–κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33–7.21 nm for ZnS and 4.95–7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  4. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Science.gov (United States)

    Osuntokun, Jejenija; Ajibade, Peter A.

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato-κS,S'-bis(N,N-dimethylthiourea-κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33-7.21 nm for ZnS and 4.95-7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  5. Defect control in room temperature deposited cadmium sulfide thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Como, N. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Martinez-Landeros, V. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Centro de Investigación en Materiales Avanzados, Monterrey, Nuevo Leon, 66600, México (Mexico); Mejia, I. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Monterrey, Nuevo Leon, 66600, México (Mexico); Nascimento, C.D.; Azevedo, G. de M; Krug, C. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91509-900 (Brazil); Quevedo-Lopez, M.A., E-mail: mquevedo@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States)

    2014-01-01

    The control of defects in cadmium sulfide thin films and its impact on the resulting CdS optical and electrical characteristics are studied. Sulfur vacancies and cadmium interstitial concentrations in the CdS films are controlled using the ambient pressure during pulsed laser deposition. CdS film resistivities ranging from 10{sup −1} to 10{sup 4} Ω-cm are achieved. Hall Effect measurements show that the carrier concentration ranges from 10{sup 19} to 10{sup 13} cm{sup −3} and is responsible for the observed resistivity variation. Hall mobility varies from 2 to 12 cm{sup 2}/V-s for the same pressure regime. Although the energy bandgap remains unaffected (∼ 2.42 eV), the optical transmittance is reduced due to the increase of defects in the CdS films. Rutherford back scattering spectroscopy shows the dependence of the CdS films stoichiometry with deposition pressure. The presence of CdS defects is attributed to more energetic species reaching the substrate, inducing surface damage in the CdS films during pulsed laser deposition. - Highlights: • CdS thin films deposited by pulsed laser deposition at room temperature. • The optical, electrical and structural properties were evaluated. • Carrier concentration ranged from 10{sup 19} to 10{sup 13} cm{sup −3}. • The chemical composition was studied by Rutherford back scattering. • The density of sulfur vacancies and cadmium interstitial was varied.

  6. Biocatalytic etching of semiconductor cadmium sulfide nanoparticles as a new platform for the optical detection of analytes.

    Science.gov (United States)

    Grinyte, R; Saa, L; Garai-Ibabe, G; Pavlov, V

    2015-12-14

    We report for the first time the enzymatic etching of cadmium sulfide nanoparticles (CdS NPs). The fluorescence of semiconductor CdS NPs is modulated irreversibly by an enzymatic reaction catalyzed by horseradish peroxidase (HRP). We observed blue-shifts of the corresponding fluorescence peaks for CdS NPs and a decrease in the intensity of the fluorescence signal.

  7. Synthesis, characterization and toxicological evaluation of maltodextrin capped cadmium sulfide nanoparticles in human cell lines and chicken embryos

    Directory of Open Access Journals (Sweden)

    Rodríguez-Fragoso Patricia

    2012-12-01

    Full Text Available Abstract Background Semiconductor Quantum dots (QDs have become quite popular thanks to their properties and wide use in biological and biomedical studies. However, these same properties entail new challenges in understanding, predicting, and managing potential adverse health effects following exposure. Cadmium and selenium, which are the major components of the majority of quantum dots, are known to be acutely and chronically toxic to cells and organisms. Protecting the core of nanoparticles can, to some degree, control the toxicity related to cadmium and selenium leakage. Results This study successfully synthesized and characterized maltodextrin coated cadmium sulfide semiconductor nanoparticles. The results show that CdS-MD nanoparticles are cytotoxic and embryotoxic. CdS-MD nanoparticles in low concentrations (4.92 and 6.56 nM lightly increased the number of HepG2 cell. A reduction in MDA-MB-231 cells was observed with concentrations higher than 4.92 nM in a dose response manner, while Caco-2 cells showed an important increase starting at 1.64 nM. CdS-MD nanoparticles induced cell death by apoptosis and necrosis in MDA-MD-231 cells starting at 8.20 nM concentrations in a dose response manner. The exposure of these cells to 11.48-14.76 nM of CdS-MD nanoparticles induced ROS production. The analysis of cell proliferation in MDA-MB-231 showed different effects. Low concentrations (1.64 nM increased cell proliferation (6% at 7 days (p 4.92 nM increased cell proliferation in a dose response manner (15-30% at 7 days. Exposures of chicken embryos to CdS-MD nanoparticles resulted in a dose-dependent increase in anomalies that, starting at 9.84 nM, centered on the heart, central nervous system, placodes, neural tube and somites. No toxic alterations were observed with concentrations of  Conclusions Our results indicate that CdS-MD nanoparticles induce cell death and alter cell proliferation in human cell lines at concentrations higher than 4.92 n

  8. Influence of cadmium sulfide nanoparticles on structural and electrical properties of polyvinyl alcohol films

    Directory of Open Access Journals (Sweden)

    J. Koteswararao

    2016-11-01

    Full Text Available Cadmium sulfide (CdS nanoparticles have been synthesized by hydrothermal method and dispersed in poly vinyl alcohol (PVA matrix in varying amounts by weight. Subsequently, PVA/CdS nanocomposites have been synthesized with the objective of investigating the effect of CdS nanoparticles on structural and electrical properties of PVA films. Structural properties were analyzed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD and scanning electron microscopy (SEM techniques. Differential scanning calorimetry (DSC was used to investigate thermal properties of PVA/CdS nanocomposites. Electrical properties were measured by using high frequency LCR meter and were found to be strongly dependent on frequency and nano CdS content. Dielectric constant decreased with increase in frequency and with increase in nanofiller concentration. AC conductivity and dielectric loss increased with frequency and decreased with increase in nano CdS content.

  9. The Potential Application of Raw Cadmium Sulfide Nanoparticles as CT Photographic Developer.

    Science.gov (United States)

    Wu, Qiang; Huang, Lingxin; Li, Zhan; An, Wenzhen; Liu, Dan; Lin, Jin; Tian, Longlong; Wang, Xinling; Liu, Bo; Qi, Wei; Wu, Wangsuo

    2016-12-01

    With the development of science and technology, new applications about nanoparticles should be explored to achieve full-scale knowledge. Therefore, in this work, the toxicity and potential application of raw cadmium sulfide nanoparticles (CdS) in vivo were further studied through ICP-OES and CTs. Surprisingly, CdS exhibited an excellent photographic property, except for finding the accumulation of CdS in the lungs, liver, spleen, and kidney with a strong dependence on time; it is also found that there were a significant uptake in the pancreas for an obvious CT imaging. And the following investigations showed that the raw CdS could damage the tissues accumulating nanoparticles. Through this work, it can be seen that the raw CdS being modified might be an excellent photographic developer for detecting cancers or other diseases.

  10. Well-dispersed cadmium sulfide prepared in the presence of laponite by microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhaohui, Han; Lewis, S.W. [Curtin Univ. of Technology, Nanochemistry Research Institute, Dept. of Applied Chemistry, WA (Australia); Qing, Yang [University of Science and Technology of China, Dept. of Chemistry, Hefei (China); Jeffrey, Shic [Sydney Univ., Dept. of Chemical Engineering, NSW (Australia); Lud, C.Q. [Sydney Univ., Australian Key Centre for Microscopy and Microanalysis, NSW (Australia)

    2008-07-01

    The reactions of cadmium chloride and various sulfur sources in the suspension of laponite produced CdS nano-particles. Laponite was used to help keep good dispersion of the sulfide particles and it also facilitated the formation of the product by providing a basic environment when carbon disulfide was used as a source of sulfur in the reaction. The amount of laponite used in the preparation, heating rate and reaction temperature were tested for their effect on result. Different sulfur source materials were used for the preparation, and reactions involved in the preparation were discussed. The varied reaction conditions produced CdS particles with varied shape and size, and in good dispersion. (authors)

  11. The Potential Application of Raw Cadmium Sulfide Nanoparticles as CT Photographic Developer

    Science.gov (United States)

    Wu, Qiang; Huang, Lingxin; Li, Zhan; An, Wenzhen; Liu, Dan; Lin, Jin; Tian, Longlong; Wang, Xinling; Liu, Bo; Qi, Wei; Wu, Wangsuo

    2016-04-01

    With the development of science and technology, new applications about nanoparticles should be explored to achieve full-scale knowledge. Therefore, in this work, the toxicity and potential application of raw cadmium sulfide nanoparticles (CdS) in vivo were further studied through ICP-OES and CTs. Surprisingly, CdS exhibited an excellent photographic property, except for finding the accumulation of CdS in the lungs, liver, spleen, and kidney with a strong dependence on time; it is also found that there were a significant uptake in the pancreas for an obvious CT imaging. And the following investigations showed that the raw CdS could damage the tissues accumulating nanoparticles. Through this work, it can be seen that the raw CdS being modified might be an excellent photographic developer for detecting cancers or other diseases.

  12. Rhizopus stolonifer mediated biosynthesis of biocompatible cadmium chalcogenide quantum dots.

    Science.gov (United States)

    Mareeswari, P; Brijitta, J; Harikrishna Etti, S; Meganathan, C; Kaliaraj, Gobi Saravanan

    2016-12-01

    We report an efficient method to biosynthesize biocompatible cadmium telluride and cadmium sulphide quantum dots from the fungus Rhizopus stolonifer. The suspension of the quantum dots exhibited purple and greenish-blue luminescence respectively upon UV light illumination. Photoluminescence spectroscopy, X-ray diffraction, and transmission electron microscopy confirms the formation of the quantum dots. From the photoluminescence spectrum the emission maxima is found to be 424 and 476nm respectively. The X-ray diffraction of the quantum dots matches with results reported in literature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability evaluation carried out on 3-days transfer, inoculum 3×10(5) cells, embryonic fibroblast cells lines shows that more than 80% of the cells are viable even after 48h, indicating the biocompatible nature of the quantum dots. A good contrast in imaging has been obtained upon incorporating the quantum dots in human breast adenocarcinoma Michigan Cancer Foundation-7 cell lines.

  13. Nitric oxide-activated hydrogen sulfide is essential for cadmium stress response in bermudagrass (Cynodon dactylon (L). Pers.).

    Science.gov (United States)

    Shi, Haitao; Ye, Tiantian; Chan, Zhulong

    2014-01-01

    Nitric oxide (NO) and hydrogen sulfide (H2S) are important gaseous molecules, serving as important secondary messengers in plant response to various biotic and abiotic stresses. However, the interaction between NO and H2S in plant stress response was largely unclear. In this study, endogenous NO and H2S were evidently induced by cadmium stress treatment in bermudagrass, and exogenous applications of NO donor (sodium nitroprusside, SNP) or H2S donor (sodium hydrosulfide, NaHS) conferred improved cadmium stress tolerance. Additionally, SNP and NaHS treatments alleviated cadmium stress-triggered plant growth inhibition, cell damage and reactive oxygen species (ROS) burst, partly via modulating enzymatic and non-enzymatic antioxidants. Moreover, SNP and NaHS treatments also induced the productions of both NO and H2S in the presence of Cd. Interestingly, combined treatments with inhibitors and scavengers of NO and H2S under cadmium stress condition showed that NO signal could be blocked by both NO and H2S inhibitors and scavengers, while H2S signal was specifically blocked by H2S inhibitors and scavengers, indicating that NO-activated H2S was essential for cadmium stress response. Taken together, we assigned the protective roles of endogenous and exogenous NO and H2S in bermudagrass response to cadmium stress, and speculated that NO-activated H2S might be essential for cadmium stress response in bermudagrass.

  14. From front contact to back contact in cadmium telluride/cadmium sulfide solar cells: Buffer layer and interfacial layer

    Science.gov (United States)

    Roussillon, Yann

    Cadmium telluride (CdTe) polycrystalline thin film solar cells, with their near optimum direct band-gap of 1.4 eV matching almost perfectly the sun radiation spectrum, are a strong contender as a less expensive alternative, among photovoltaic materials, than the more commonly used silicon-based cells. Polycrystalline solar cells are usually deposited over large areas. Such devices often exhibit strong fluctuations (nonuniformities) in electronic properties, which originate from deposition and post-deposition processes, and are detrimental to the device performance. Therefore their effects need to be constrained. A new approach in this work was, when a CdS/CdTe solar cell is exposed to light and immersed in a proper electrolyte, fluctuations in surface potential can drive electrochemical reactions which result in a nonuniform interfacial layer that could balance the original nonuniformity. This approach improved the device efficiency for CdS/CdTe photovoltaic devices from 1--3% to 11--12%. Cadmium sulfide (CdS), used as a window layer and heterojunction partner to CdTe, is electrically inactive and absorb light energies above its band-gap of 2.4 eV. Therefore, to maximize the device efficiency, a thin US layer needs to be used. However, more defects, such as pinholes, are likely to be present in the film, leading to shunts. A resistive transparent layer, called buffer layer, is therefore deposited before CdS. A key observation was that the open-circuit voltage (Voc) for cells made using a buffer layer was high, around 800 mV, similar to cells without buffer layer after Cu doping. The standard p-n junction theory cannot explain this phenomena, therefore an alternative junction mechanism, similar to metal-insulator-semiconductor devices, was developed. Furthermore, alternative Cu-free back-contacts were used in conjunction with a buffer layer. The Voc of the devices was found to be dependent of the back contact used. This change occurs as the back-contact junction

  15. 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.

  16. Investigation of annealing temperature effect on magnetron sputtered cadmium sulfide thin film properties

    Science.gov (United States)

    Akbarnejad, E.; Ghorannevis, Z.; Abbasi, F.; Ghoranneviss, M.

    2016-12-01

    Cadmium sulfide (CdS) thin films are deposited on the fluorine doped tin oxide coated glass substrate using the radio frequency magnetron sputtering setup. The effects of annealing in air on the structural, morphological, and optical properties of CdS thin film are studied. Optimal annealing temperature is investigated by annealing the CdS thin film at different annealing temperatures of 300, 400, and 500 °C. Thin films of CdS are characterized by X-ray diffractometer analysis, field emission scanning electron microscopy, atomic force microscopy, UV-Vis-NIR spectrophotometer and four point probe. The as-grown CdS films are found to be polycrystalline in nature with a mixture of cubic and hexagonal phases. By increasing the annealing temperature to 500 °C, CdS film showed cubic phase, indicating the phase transition of CdS. It is found from physical characterizations that the heat treatment in air increased the mean grain size, the transmission, and the surface roughness of the CdS thin film, which are desired to the application in solar cells as a window layer material.

  17. Cadmium Sulfide Thin Films Deposited onto MWCNT/Polysulfone Substrates by Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    M. Moreno

    2016-01-01

    Full Text Available Cadmium sulfide (CdS thin films were deposited by chemical bath deposition (CBD onto polymeric composites with electric field-aligned multiwall carbon nanotubes (MWCNTs. MWCNT/polysulfone composites were prepared by dispersing low concentrations of MWCNTs within dissolved polysulfone (PSF. An alternating current electric field was “in situ” applied to align the MWCNTs within the dissolved polymer along the field direction until the solvent was evaporated. 80 μm thick solid MWCNT/PSF composites with an electrical conductivity 13 orders of magnitude higher than the conductivity of the neat PSF were obtained. The MWCNT/PSF composites were subsequently used as flexible substrates for the deposition of CdS thin films by CBD. Transparent and adherent CdS thin films with an average thickness of 475 nm were obtained. The values of the energy band gap, average grain size, rms roughness, crystalline structure, and preferential orientation of the CdS films deposited onto the polymeric substrate were very similar to the corresponding values of the CdS deposited onto glass (conventional substrate. These results show that the MWCNT/PSF composites with electric field-tailored MWCNTs represent a suitable option to be used as flexible conducting substrate for CdS thin films, which represents an important step towards the developing of flexible systems for photovoltaic applications.

  18. Cadmium Sulfide Nanoparticles Synthesized by Microwave Heating for Hybrid Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Claudia Martínez-Alonso

    2014-01-01

    Full Text Available Cadmium sulfide nanoparticles (CdS-n are excellent electron acceptor for hybrid solar cell applications. However, the particle size and properties of the CdS-n products depend largely on the synthesis methodologies. In this work, CdS-n were synthetized by microwave heating using thioacetamide (TA or thiourea (TU as sulfur sources. The obtained CdS-n(TA showed a random distribution of hexagonal particles and contained TA residues. The latter could originate the charge carrier recombination process and cause a low photovoltage (Voc, 0.3 V in the hybrid solar cells formed by the inorganic particles and poly(3-hexylthiophene (P3HT. Under similar synthesis conditions, in contrast, CdS-n synthesized with TU consisted of spherical particles with similar size and contained carbonyl groups at their surface. CdS-n(TU could be well dispersed in the nonpolar P3HT solution, leading to a Voc of about 0.6–0.8 V in the resulting CdS-n(TU : P3HT solar cells. The results of this work suggest that the reactant sources in microwave methods can affect the physicochemical properties of the obtained inorganic semiconductor nanoparticles, which finally influenced the photovoltaic performance of related hybrid solar cells.

  19. An amperometric chloramphenicol immunosensor based on cadmium sulfide nanoparticles modified-dendrimer bonded conducting polymer.

    Science.gov (United States)

    Kim, Dong-Min; Rahman, Md Aminur; Do, Minh Hien; Ban, Changill; Shim, Yoon-Bo

    2010-03-15

    An amperometric chloramphenicol (CAP) immunosensor was fabricated by covalently immobilizing anti-chloramphenicol acetyl transferase (anti-CAT) antibody on cadmium sulfide nanoparticles (CdS) modified-dendrimer that was bonded to the conducting polymer (poly 5, 2': 5', 2''-terthiophene-3'-carboxyl acid (poly-TTCA)) layer. The AuNPs, dendrimers, and CdS nanoparticles were deposited onto the polymer layer in order to enhance the sensitivity of the sensor probes. The particle sizes were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The immobilization of dendrimers, CdS, and anti-CAT were confirmed using energy disruptive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) techniques. The detection of CAP was based on the competitive immuno-interaction between the free- and labeled-CAP for active sites of the anti-CAT. Hydrazine was used as the label for CAP, and it electrochemically catalyzed the reduction of H(2)O(2) at -0.35 V vs. Ag/AgCl. Under optimized conditions, the proposed immunosensor exhibited a linear range of CAP detection between 50 pg/mL and 950 pg/mL, and the detection limit was 45 pg/mL. The immunosensor was examined in real meat samples for the analysis of CAP.

  20. Relation of asid-volatile sulfide and clay content of sediment to the bioavailability of zinc and cadmium: laboratory plus field experiment

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Organic matter and iron and maganese oxides have been considered as the major affecting factors for metals in anoxic or oxidized sediment. In recent research, clay and sulfide are found as major factors in oxic or oxidized sediments that might affect bioavailability of metals. To test this hypothesis, the influence of sulfide, measured as acid-volatile sulfide (AVS), and clay content on the bioavailability of zinc and cadmium in sediments was examined. Laboratory simulative experiment and field verification experiment were conducted,showing that the bioavailability of zinc and cadmium is strongly correlated to AVS and clay content in sediments. Taking into account both AVS and clay parameters in sediments together can better indicate the bioavailability of zinc and cadmium rather than considering one of them alone.

  1. A novel single-precursor nanoparticle growth technique for luminescent metal sulfides (cadmium sulfide, lead sulfide, zinc sulfide) with hydrophilic surface modification

    Science.gov (United States)

    Rama, Jason Eric

    In recent years luminescent semiconductor nanoparticles (quantum dots) have attracted considerable attention, mostly due to their size-dependent tunable spectroscopic properties. Currently, fluorescing particles are put to use as biological labels alongside, or even replacing, fluorescing molecular probes. They are characterized by very narrow and tunable (excitonic) emission bands and long-range stability even under illumination. In particular, the colloidal chemistry approach to luminescent nanoparticle fabrication has been favored due to its relative ease, and high size tunability. However, the development of highly monodisperse, size tunable, and highly stable aqueous colloidal suspension fabrication methodologies has to date been very limited. In this work, the synthesis of luminescent MS (M = Cd, Pb, Zn) nanoparticles was achieved through the development and implementation of three characteristically different reaction methodologies: a spontaneous precipitation reaction (the metal chloride method), a controlled precipitation reaction (the metal oxide method), and a novel controlled aqueous decomposition reaction (the metal ethyl xanthate method) in an alkylamine solvent of 4-dimethylaminopyridine (DMAP). Varying degrees of monodispersity were achieved for the various methods, as evidenced by the photoluminescence full-width at half-maximum (FWHM). Spectral widths range from 150 nm for spontaneous precipitation methods, to as small as 20 nm for each of the temperature-controlled nucleation and ripening methods. For each of the methods, attempts at size tunability through variation of precursor concentration, growth temperature and growth time were performed. This resulted in the demonstration of an ability to fabricate size-specified semiconducting nanoparticles in the sub-10 nm size range. A demonstration of aqueous-organic-aqueous phase transfer versatility of the metal ethyl xanthate-DMAP fabrication method advances the potential of this particular method

  2. CADMIUM SOLUBILITY IN PADDY SOILS: EFFECTS OF SOIL OXIDATION, METAL SULFIDES AND COMPETITIVE IONS.

    Science.gov (United States)

    Cadmium (Cd) is a non-essential element for human nutrition and is an agricultural soil contaminant. Cadmium solubility in paddy soils affects Cd accumulation in the grain of rice. This is a human health risk, exacerbated by the fact that rice grains are deficient in iron (Fe) an...

  3. Photocatalytic Activities of Copper Doped Cadmium Sulfide Microspheres Prepared by a Facile Ultrasonic Spray-Pyrolysis Method

    Directory of Open Access Journals (Sweden)

    Jinzhan Su

    2016-06-01

    Full Text Available Ultrasonic spray pyrolysis is a superior method for preparing and synthesizing spherical particles of metal oxide or sulfide semiconductors. Cadmium sulfide (CdS photocatalysts with different sizes and doped-CdS with different dopants and doping levels have been synthesized to study their properties of photocatalytic hydrogen production from water. The CdS photocatalysts were characterized with scanning electron microscopy (SEM, X-ray fluorescence-spectrometry (XRF, UV-Vis absorption spectra and X-ray diffraction (XRD to study their morphological and optical properties. The sizes of the prepared CdS particles were found to be proportional to the concentration of the metal nitrates in the solution. The CdS photocatalyst with smaller size showed a better photocatalytic activity. In addition, Cu doped CdS were also deposited and their photocatalytic activities were also investigated. Decreased bandgaps of CdS synthesized with this method were found and could be due to high density surface defects originated from Cd vacancies. Incorporating the Cu elements increased the bandgap by taking the position of Cd vacancies and reducing the surface defect states. The optimal Cu-doped level was found to be 0.5 mol % toward hydrogen evolution from aqueous media in the presence of sacrificial electron donors (Na2S and Na2SO3 at a pH of 13.2. This study demonstrated that ultrasonic spray pyrolysis is a feasible approach for large-scale photocatalyst synthesis and corresponding doping modification.

  4. Photocatalytic Activities of Copper Doped Cadmium Sulfide Microspheres Prepared by a Facile Ultrasonic Spray-Pyrolysis Method.

    Science.gov (United States)

    Su, Jinzhan; Zhang, Tao; Li, Yufeng; Chen, Yubin; Liu, Maochang

    2016-06-15

    Ultrasonic spray pyrolysis is a superior method for preparing and synthesizing spherical particles of metal oxide or sulfide semiconductors. Cadmium sulfide (CdS) photocatalysts with different sizes and doped-CdS with different dopants and doping levels have been synthesized to study their properties of photocatalytic hydrogen production from water. The CdS photocatalysts were characterized with scanning electron microscopy (SEM), X-ray fluorescence-spectrometry (XRF), UV-Vis absorption spectra and X-ray diffraction (XRD) to study their morphological and optical properties. The sizes of the prepared CdS particles were found to be proportional to the concentration of the metal nitrates in the solution. The CdS photocatalyst with smaller size showed a better photocatalytic activity. In addition, Cu doped CdS were also deposited and their photocatalytic activities were also investigated. Decreased bandgaps of CdS synthesized with this method were found and could be due to high density surface defects originated from Cd vacancies. Incorporating the Cu elements increased the bandgap by taking the position of Cd vacancies and reducing the surface defect states. The optimal Cu-doped level was found to be 0.5 mol % toward hydrogen evolution from aqueous media in the presence of sacrificial electron donors (Na₂S and Na₂SO₃) at a pH of 13.2. This study demonstrated that ultrasonic spray pyrolysis is a feasible approach for large-scale photocatalyst synthesis and corresponding doping modification.

  5. Effects of Buffer Salt Concentration on the Dominated Deposition Mechanism and Optical Characteristics of Chemically Deposited Cadmium Sulfide Thin Films

    Science.gov (United States)

    Kakhaki, Z. Makhdoumi; Youzbashi, A.; Sangpour, P.; Kazemzadeh, A.; Naderi, N.; Bazargan, A. M.

    2016-02-01

    Effects of buffer salt concentration on the rate of deposition, dominated deposition mechanism and subsequently the structural, morphological, and optical properties of cadmium sulfide (CdS) thin films deposited by chemical bath deposition (CBD) on glass substrate were investigated. The precursors were chosen to be cadmium chloride (CdCl2) as the cadmium source, thiourea (CS(NH2)2) as the sulfur source, ammonium nitrate (NH4NO3) as the buffer salt and ammonia as the complexing agent and the pH controller. The influence of the NH4NO3 concentration on the structure, morphology, film uniformity, stoichiometry and optical properties of CdS thin films was also studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscope, uv-visible and photoluminescence (PL) spectroscopes. The XRD studies revealed that all the deposited films exhibited a (002)h/(111)c preferred orientation. The crystallite size was increased from 20nm to 30nm by the increase of concentration of NH4NO3 from 0.5M to 2.5M. The morphology of CdS thin films were agglomerated spherical particles consisted of smaller particles. The surface of thin films deposited at the NH4NO3 concentration of 0.5M was compact and smooth. The increase of the concentration of NH4NO3 decreased the packing density of the films. The optical band gap was in the range of 2.25-2.4eV, which was decreased by the decrement of packing density. The PL spectra showed two peaks centered at 400nm and 500nm which are attributed to violet and band-to-band emissions, respectively.

  6. Incorporation of sulfide ions into the cadmium(II) thiolate cluster of Cicer arietinum metallothionein2.

    Science.gov (United States)

    Wan, Xiaoqiong; Freisinger, Eva

    2013-01-18

    The plant metallothionein2 from Cicer arietinum (chickpea), cic-MT2, is known to coordinate five divalent metal ions such as Zn(II) or Cd(II), which are arranged in a single metal thiolate cluster. When the Zn(II) form of the protein is titrated with Cd(II) ions in the presence of sulfide ions, an increased Cd(II) binding capacity and concomitant incorporation of sulfide ions into the cluster are observed. The exact stoichiometry of this novel cluster, its spectroscopic properties, and the significantly increased pH stability are analyzed with different techniques, including UV and circular dichroism spectroscopy and colorimetric assays. Limited proteolytic digestion provides information about the spacial arrangement of the cluster within the protein. Increasing the Cd(II) scavenging properties of a metallothionein by additionally recruiting sulfide ions might be an economic and very efficient detoxification strategy for plants.

  7. Cadmium-induced hydrogen sulfide synthesis is involved in cadmium tolerance in Medicago sativa by reestablishment of reduced (homo)glutathione and reactive oxygen species homeostases.

    Science.gov (United States)

    Cui, Weiti; Chen, Huiping; Zhu, Kaikai; Jin, Qijiang; Xie, Yanjie; Cui, Jin; Xia, Yan; Zhang, Jing; Shen, Wenbiao

    2014-01-01

    Until now, physiological mechanisms and downstream targets responsible for the cadmium (Cd) tolerance mediated by endogenous hydrogen sulfide (H2S) have been elusive. To address this gap, a combination of pharmacological, histochemical, biochemical and molecular approaches was applied. The perturbation of reduced (homo)glutathione homeostasis and increased H2S production as well as the activation of two H2S-synthetic enzymes activities, including L-cysteine desulfhydrase (LCD) and D-cysteine desulfhydrase (DCD), in alfalfa seedling roots were early responses to the exposure of Cd. The application of H2S donor sodium hydrosulfide (NaHS), not only mimicked intracellular H2S production triggered by Cd, but also alleviated Cd toxicity in a H2S-dependent fashion. By contrast, the inhibition of H2S production caused by the application of its synthetic inhibitor blocked NaHS-induced Cd tolerance, and destroyed reduced (homo)glutathione and reactive oxygen species (ROS) homeostases. Above mentioned inhibitory responses were further rescued by exogenously applied glutathione (GSH). Meanwhile, NaHS responses were sensitive to a (homo)glutathione synthetic inhibitor, but reversed by the cotreatment with GSH. The possible involvement of cyclic AMP (cAMP) signaling in NaHS responses was also suggested. In summary, LCD/DCD-mediated H2S might be an important signaling molecule in the enhancement of Cd toxicity in alfalfa seedlings mainly by governing reduced (homo)glutathione and ROS homeostases.

  8. Cadmium-induced hydrogen sulfide synthesis is involved in cadmium tolerance in Medicago sativa by reestablishment of reduced (homoglutathione and reactive oxygen species homeostases.

    Directory of Open Access Journals (Sweden)

    Weiti Cui

    Full Text Available Until now, physiological mechanisms and downstream targets responsible for the cadmium (Cd tolerance mediated by endogenous hydrogen sulfide (H2S have been elusive. To address this gap, a combination of pharmacological, histochemical, biochemical and molecular approaches was applied. The perturbation of reduced (homoglutathione homeostasis and increased H2S production as well as the activation of two H2S-synthetic enzymes activities, including L-cysteine desulfhydrase (LCD and D-cysteine desulfhydrase (DCD, in alfalfa seedling roots were early responses to the exposure of Cd. The application of H2S donor sodium hydrosulfide (NaHS, not only mimicked intracellular H2S production triggered by Cd, but also alleviated Cd toxicity in a H2S-dependent fashion. By contrast, the inhibition of H2S production caused by the application of its synthetic inhibitor blocked NaHS-induced Cd tolerance, and destroyed reduced (homoglutathione and reactive oxygen species (ROS homeostases. Above mentioned inhibitory responses were further rescued by exogenously applied glutathione (GSH. Meanwhile, NaHS responses were sensitive to a (homoglutathione synthetic inhibitor, but reversed by the cotreatment with GSH. The possible involvement of cyclic AMP (cAMP signaling in NaHS responses was also suggested. In summary, LCD/DCD-mediated H2S might be an important signaling molecule in the enhancement of Cd toxicity in alfalfa seedlings mainly by governing reduced (homoglutathione and ROS homeostases.

  9. 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.

  10. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xianmei; Wang, Yilin; Gule, Teri; Luo, Qiang [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Zhou, Liya, E-mail: zhouliyatf@163.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Gong, Fuzhong [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China)

    2013-03-15

    Highlights: ► Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ► The fabricated white LEDs show good white balance. ► CdSe QDs present well green to yellow band luminescence. ► CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors.

  11. Impact of back-contact materials on performance and stability of cadmium sulfide/cadmium telluride solar cells

    Science.gov (United States)

    Demtsu, Samuel H.

    Thin-film CdTe based solar cells are one of the leading contenders for providing lowcost and pollution-free energy, The formation of a stable, low resistance, non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with this technology in the fabrication of efficient and stable solar cells. The premise of this thesis is a systematic study of the impact of back-contact materials on the initial performance and the degradation of CdS/CdTe solar cells. Two different back-contact structures that incorporate Cu as a key element are investigated in this study: (a) Cu1.4Te:HgTe-doped graphite and (b) evaporated-Cu back contacts. The effect of Cu inclusion is not limited to the back-contact layer where it is deposited. Cu is a known fast diffuser in p-CdTe, and therefore, a significant amount of Cu reaches both the CdTe and US layers. Hence, the effect of the presence of Cu on the individual layers: back-contact, the absorber (CdTe), and the window (CdS) layers is discussed respectively. The effect of different metals used to form the current-carrying electrode following the Cu layer is also evaluated. Devices are studied through current-voltage (JV) measurements at different temperatures and intensities, quantum efficiency (QE) measurements under light and voltage bias, capacitance-voltage (CV), drive-level-capacitance-profiling (DLCP), and time-resolved photoluminescence (TRPL) measurements. Numerical simulation is also used to reproduce and explain some of the experimental results. In devices made without Cu, a current-limiting effect, rollover (distortion) in the current-voltage characteristic, was observed. With the inclusion of a small amount of Cu (5-nm), however, the distortion disappeared, and higher FF was obtained. The performance of these devices was comparable to devices made with the standard Cu-doped graphite paste contacts when the same CdTe absorber is used. Small amount of Cu (5-20 nm) partially diffused into the

  12. Direct electrochemistry and electrocatalysis of horseradish peroxidase with hyaluronic acid-ionic liquid-cadmium sulfide nanorod composite material

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhihong [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Li Xia; Wang Yan [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Zeng Yan [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Sun Wei, E-mail: sunwei@qust.edu.cn [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Huang Xintang [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China)

    2010-06-18

    A new composite material consisted of hyaluronic acid (HA), ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF{sub 4}) and cadmium sulfide (CdS) nanorod was fabricated and used for the immobilization of horseradish peroxidase (HRP) on the surface of a carbon ionic liquid electrode (CILE), which was prepared with 1-ethyl-3-methyl-imidazolium ethylsulphate ([EMIM]EtOSO{sub 3}) as modifier. Spectroscopic results indicated that HRP remained its native structure in the composite film. Based on the synergistic effect of the materials used, an obvious promotion to the direct electron transfer efficient between HRP and CILE was achieved with a pair of well-defined redox peaks appeared in 0.1 mol L{sup -1} phosphate buffer solution, indicating the realization of the direct electrochemistry of HRP. The immobilized HRP showed good electrocatalytic activity towards the reduction of trichloroacetic acid and H{sub 2}O{sub 2} with the electrochemical parameters calculated. Based on the fabricated electrode, a new third-generation electrochemical biosensor was constructed with good stability and reproducibility.

  13. Size-controlled one-pot synthesis of fluorescent cadmium sulfide semiconductor nanoparticles in an apoferritin cavity

    Science.gov (United States)

    Iwahori, K.; Yamashita, I.

    2008-12-01

    A simple size-controlled synthesis of cadmium sulfide (CdS) nanoparticle (NP) cores in the cavity of apoferritin from horse spleen (HsAFr) was performed by a slow chemical reaction synthesis and a two-step synthesis protocol. We found that the CdS NP core synthesis was slow and that premature CdS NP cores were formed in the apoferritin cavity when the concentration of ammonia water was low. It was proven that the control of the ammonia water concentration can govern the CdS NP core synthesis and successfully produce size-controlled CdS NP cores with diameters from 4.7 to 7.1 nm with narrow size dispersion. X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy (HR-TEM) observation characterized the CdS NP cores obtained as cubic polycrystalline NPs, which showed photoluminescence with red shifts depending on their diameters. From the research of CdS NP core synthesis in the recombinant apoferritins, the zeta potential of apoferritin is important for the biomineralization of CdS NP cores in the apoferritin cavity. These synthesized CdS NPs with different photoluminescence properties will be applicable in a wide variety of nano-applications.

  14. Hydrogen Sulfide Alleviates Cadmium-Induced Cell Death through Restraining ROS Accumulation in Roots of Brassica rapa L. ssp. pekinensis

    Science.gov (United States)

    2015-01-01

    Hydrogen sulfide (H2S) is a cell signal molecule produced endogenously and involved in regulation of tolerance to biotic and abiotic stress in plants. In this work, we used molecular biology, physiology, and histochemical methods to investigate the effects of H2S on cadmium- (Cd-) induced cell death in Chinese cabbage roots. Cd stress stimulated a rapid increase of endogenous H2S in roots. Additionally, root length was closely related to the cell death rate. Pretreatment with sodium hydrosulfide (NaHS), a H2S donor, alleviated the growth inhibition caused by Cd in roots—this effect was more pronounced at 5 μM NaHS. Cd-induced cell death in roots was significantly reduced by 5 μM NaHS treatment. Under Cd stress, activities of the antioxidant enzymes were significantly enhanced in roots. NaHS + Cd treatment made their activities increase further compared with Cd exposure alone. Enhanced antioxidant enzyme activity led to a decline in reactive oxygen species accumulation and lipid peroxidation. In contrast, these effects were reversed by hydroxylamine, a H2S inhibitor. These results suggested that H2S alleviated the cell death caused by Cd via upregulation of antioxidant enzyme activities to remove excessive reactive oxygen species and reduce cell oxidative damage. PMID:26078819

  15. Hydrogen Sulfide Alleviates Cadmium-Induced Cell Death through Restraining ROS Accumulation in Roots of Brassica rapa L. ssp. pekinensis

    Directory of Open Access Journals (Sweden)

    Liping Zhang

    2015-01-01

    Full Text Available Hydrogen sulfide (H2S is a cell signal molecule produced endogenously and involved in regulation of tolerance to biotic and abiotic stress in plants. In this work, we used molecular biology, physiology, and histochemical methods to investigate the effects of H2S on cadmium- (Cd- induced cell death in Chinese cabbage roots. Cd stress stimulated a rapid increase of endogenous H2S in roots. Additionally, root length was closely related to the cell death rate. Pretreatment with sodium hydrosulfide (NaHS, a H2S donor, alleviated the growth inhibition caused by Cd in roots—this effect was more pronounced at 5 μM NaHS. Cd-induced cell death in roots was significantly reduced by 5 μM NaHS treatment. Under Cd stress, activities of the antioxidant enzymes were significantly enhanced in roots. NaHS + Cd treatment made their activities increase further compared with Cd exposure alone. Enhanced antioxidant enzyme activity led to a decline in reactive oxygen species accumulation and lipid peroxidation. In contrast, these effects were reversed by hydroxylamine, a H2S inhibitor. These results suggested that H2S alleviated the cell death caused by Cd via upregulation of antioxidant enzyme activities to remove excessive reactive oxygen species and reduce cell oxidative damage.

  16. Effect of thermal annealing on the properties of cadmium sulfide deposited via chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Faisal R., E-mail: ahmad@ge.com; Yakimov, Aharon; Davis, Robert J.; Her, Jae-Hyuk; Cournoyer, James R.; Ayensu, Nana Menya

    2013-05-01

    This study elucidates how post-deposition annealing in air of CdS thin films deposited via chemical bath deposition, influences the defects and impurities in the films, which in turn affect the electrical conductivity and optical transparency of the films. The electrical properties of the annealed CdS films were characterized using a van der Pauw Hall effect measurement method. Using low-temperature photoluminescence measurements, a variety of sub-bandgap energy levels were observed and identified that are believed to play a critical role in impacting the concentration of carriers in the films. In addition, we studied the optical transmission and crystalline quality of the films as a function of the different annealing conditions. - Highlights: ► Annealing CdS affects its bandgap, structure and electrical conductivity. ► Low temperature photoluminescence spectra show how annealing affects CdS. ► Carrier concentration affected sulfur vacancies and cadmium interstitials.

  17. Roles of hydrogen sulfide and nitric oxide in the alleviation of cadmium-induced oxidative damage in alfalfa seedling roots.

    Science.gov (United States)

    Li, Le; Wang, Yanqin; Shen, Wenbiao

    2012-06-01

    Despite hydrogen sulfide (H(2)S) and nitric oxide (NO) are important endogenous signals or bioregulators involved in many vital aspects of plant growth and responses against abiotic stresses, little information was known about their interaction. In the present study, we evaluated the effects of H(2)S and NO on alfalfa (Medicago sativa L.) plants exposed to cadmium (Cd) stress. Pretreatment with an H(2)S donor sodium hydrosulfide (NaHS) and well-known NO donor sodium nitroprusside (SNP) decreased the Cd toxicity. This conclusion was supported by the decreases of lipid peroxidation as well as the amelioration of seedling growth inhibition and Cd accumulation, in comparison with the Cd-stressed alone plants. Total activities and corresponding transcripts of antioxidant enzymes, including superoxide dismutase, peroxidase and ascorbate peroxidase were modulated differentially, thus leading to the alleviation of oxidative damage. Effects of H(2)S above were reversed by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO), the specific scavenger of NO. By using laser confocal scanning microscope combined with Greiss reagent method, further results showed that NO production increased significantly after the NaHS pretreatment regardless of whether Cd was applied or not, all of which were obviously inhibited by cPTIO. These decreases of NO production were consistent with the exaggerated syndromes associated with Cd toxicity. Together, above results suggested that NO was involved in the NaHS-induced alleviation of Cd toxicity in alfalfa seedlings, and also indicated that there exists a cross-talk between H(2)S and NO responsible for the increased abiotic stress tolerance.

  18. High-Pressure Hydrogen Sulfide by Diffusion Quantum Monte Carlo

    CERN Document Server

    Azadi, Sam

    2016-01-01

    We use the diffusion quantum Monte Carlo to revisit the enthalpy-pressure phase diagram of the various products from the different proposed decompositions of H$_2$S at pressures above 150~GPa. Our results entails a revision of the ground-state enthalpy-pressure phase diagram. Specifically, we find that the C2/c HS$_2$ structure is persistent up to 440~GPa before undergoing a phase transition into the C2/m phase. Contrary to density functional theory, our calculations suggest that the C2/m phase of HS is more stable than the I4$_1$/amd HS structure over the whole pressure range from 150 to 400 GPa. Moreover, we predict that the Im-3m phase is the most likely candidate for H$_3$S, which is consistent with recent experimental x-ray diffraction measurements.

  19. Synthesis of Cadmium Selenide Quantum Dots and Their Cytotoxicity

    OpenAIRE

    Liu, Ruoxi

    2013-01-01

    Cadmium selenide (CdSe) nanoparticles (NPs) have applications in biomedical, biochemistry, bioimaging areas through different methods such as cell labelling and drug delivery (Chapter1). This study aims to test the optical and biological properties of CdSe NPs so that its applications can be improved in these areas in the future. Three types of CdSe NPs have been synthesised using a wet chemical method with the molar ratio of Cd:Se 10:1, 4:1 and 1:1. The observed luminescence of the CdSe N...

  20. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    OpenAIRE

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M.

    2015-01-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, ...

  1. A Rapid and Cost-Effective Laser Based Synthesis of High Purity Cadmium Selenide Quantum Dots.

    Science.gov (United States)

    Gondall, M A; Qahtan, Talal F; Dastageer, M A; Yamani, Z H; Anjum, D H

    2016-01-01

    A rapid and cost effective method is developed to synthesize high purity cadmium Selenide (CdSe) quantum dots in acetone medium using second harmonic of Nd:YAG nanosecond pulsed laser of 532 nm wavelength. The thermal agglomeration due the nanosecond pulse duration of the laser was successfully eliminated by using unfocussed laser beam and thereby providing a favorable conditions for the synthesis of quantum dots having the grain size of 3 nm. The morphological and optical characterizations like XRD, HRTEM, optical absorption of the synthesized CdSe quantum dots, reveal that the material possesses the similar characteristics of the one synthesized through cumbersome wet chemical methods. Relative to the CdSe bulk material, the synthesized CdSe quantum dots showed a blue shift in the measured band gap energy from near infrared spectral region to visible region, making this material very attractive for many solar energy harvesting applications like photo-catalysis and solar cells.

  2. Monitoring Hydrogen Sulfide Using a Quantum Cascade Laser Based Trace Gas Sensing System

    Institute of Scientific and Technical Information of China (English)

    WANG Ling-Fang; SHARPLES Thomas-Roben

    2011-01-01

    @@ We present the detection of hydrogen sulfide (HS) in a quantum cascade laser (QCL) based gas sensing system employing direct laser absorption spectroscopy.The sensitivity is obtained to be 3.61 × 10 cm Hz and the HS broadening coefficient in N is analyzed by fitting to the plot of the Lorentzian half width at the half maximum as a function of N pressure is 0.1124±0.0031 cm.atm.A simulation based on data from the HITRAN database shows broad agreement with the experimentally obtained spectrum.

  3. Photocatalytic Oxidation of Hydrosulfide Ions by Molecular Oxygen Over Cadmium Sulfide Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Raevskaya, A. E., E-mail: photochem@e-mail.ru; Stroyuk, A.L., E-mail: photochem@e-mail.ru; Kuchmii, S.Ya. [National Academy of Sciences of Ukraine, L. V. Pysarzhevsky Institute of Physical Chemistry (Ukraine)], E-mail: photochem@e-mail.ru

    2004-06-15

    Photocatalytic activity of CdS nanoparticles in hydrosulfide-ions air oxidation was revealed and thoroughly investigated. HS{sup -} photooxidation in the presence of CdS nanoparticles results predominantly in the formation of SO{sub 3}{sup 2-} and SO{sub 4}{sup 2-} ions. Photocatalytic activity of ultrasmall CdS crystallites in HS{sup -} photooxidation is much more pronounced as compared to bulk CdS crystals due to high surface area of nanoparticles, their negligible light scattering, improved separation of photogenerated charge carriers etc. It was shown that hydrosulfide ions can be oxidized in two ways. The first is HS{sup -} oxidation by the CdS valence band holes. This process rate depends on the rate of comparatively slow reaction between molecular oxygen and CdS conduction band electrons. The second reaction route is the chain-radical HS{sup -} oxidation induced by photoexcited CdS nanoparticles and propagating in the bulk of a solution. In conditions favourable to chain-radical oxidation of HS{sup -}(i.e. at low light intensities and CdS concentration and high oxygen and Na{sub 2}S concentrations) quantum yields of the photoreaction reach 2.5.

  4. Electrical and optoelectrical modification of cadmium sulfide nanobelts by low-energy electron beam irradiation

    Science.gov (United States)

    Zhang, Lijie; Liu, Manman; Zhao, Mei; Dong, Youqing; Zou, Chao; Yang, Keqin; Yang, Yun; Huang, Shaoming; Zhu, Da-Ming

    2016-09-01

    In this report, we describe a method for modifying electrical and optoelectrical properties of CdS nanobelts using low-energy (lower than 10 keV) e-beam irradiation in a scanning electron microscope. The electrical conductivity of the nanobelts was dramatically improved via the irradiation of e-beams. The modified conductivity of the nanobelts depends on the energy of the e-beam; it exhibits a larger photocurrent and higher external quantum efficiency but slower time-response than that before the modification. A possible mechanism about the modification is the increase of electron accumulation (injected electrons) in the nanobelts due to e-beam irradiation. In addition, the optoelectrical modification could be caused by the trapped electrons in the nanobelts and the decrease of contact resistance between the nanobelts and metal electrodes induced by e-beam irradiation. The results of this work are significant for the in situ study of semiconductor nanostructures in the electron microscope. Besides, the method of electrical and optoelectrical modification presented here has potential application in electronics and optoelectronics.

  5. Fluorescent cadmium sulfide nanoparticles for selective and sensitive detection of toxic pesticides in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Walia, Shanka; Acharya, Amitabha, E-mail: amitabhachem@gmail.com [CSIR-Institute of Himalayan Bioresource Technology, Biotechnology Division (India)

    2014-12-15

    The detection of pesticide residues in ground water, food, or soil samples is extremely important. The currently available laboratory techniques have several drawbacks and needs to be replaced. Fluorescent chemosensors for pesticide detection were reported in the literature, with few reports published on quantum dot-based pesticide sensors, but none of these were focused toward differentiating organophosphorus and organochlorine pesticides specifically. In this respect, glutathione-coated CdS nanoparticles were synthesized and characterized. The TEM studies of the nanoparticles suggested mostly monodispersed spherical particles, with size in the range of 11.5±1 nm. The prepared fluorescent nanoparticles were found to selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles ∼ 2.5 times. Similar studies carried out with organophosphorous pesticide dimethoate did not result any change in the fluorescence intensity of the nanoparticles. Further studies carried out with commercially available pesticide solutions, also confirmed similar results. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol. Control experiments suggested possible role of both amine and carboxylic acid functional groups of glutathione in the recognition of dicofol. The limit of detection of dicofol was found to be ∼ 55±11 ppb.Graphical AbstractGlutathione-coated CdS nanoparticles selectively recognize organochlorine pesticide dicofol among all the other pesticides studied, by increasing the fluorescence intensity of the nanoparticles. The TEM, SEM, and DLS studies suggested aggregation of the nanoparticles in the presence of dicofol.

  6. Biosynthesis and characterization of cadmium sulfide nanoparticles – An emphasis of zeta potential behavior due to capping

    Energy Technology Data Exchange (ETDEWEB)

    Sankhla, Aryan, E-mail: aaryansankhla@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Sharma, Rajeshwar; Yadav, Raghvendra Singh [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Kashyap, Diwakar [Department of Biological Chemistry, Ariel University, Ariel, 40700 (Israel); Kothari, S.L. [Institute of Biotechnology, Amity University, Jaipur, 303002 (India); Kachhwaha, S. [Department of Botany, University of Rajasthan, Jaipur, 302004 (India)

    2016-02-15

    Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m{sup 2}/g and 117 ± 2.41 m{sup 2}/g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area

  7. Synthesis and optical properties of quantum-size metal sulfide particles in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nedeljkovic, J.M.; Patel, R.C.; Kaufman, P.; Joyce-Pruden, C.; O' Leary, N. (Clarkson Univ., Potsdam, NY (United States))

    1993-04-01

    During the past decade, small-particle' research has become quite popular in various fields of chemistry and physics. The recognition of quantum-size effects in very small colloidal particles has led to renewed interest in this area. Small particles' are clusters of atoms or molecules ranging in size from 1 nm to almost 10 nm or having agglomeration numbers from 10 up to a few hundred. In other words, small particles fall in size between single atoms or molecules and bulk materials. The agglomeration number specifies the number of individual atoms or molecules in a given cluster. The research in this area is interdisciplinary, and it links colloidal science and molecular chemistry. The symbiosis of these two areas of research has revealed some intriguing characteristics of small particles. This experiment illustrates the following: simple colloidal techniques for the preparation of two different types of quantum-size metal sulfide particles; the blue shift of the measured optical absorption spectra when the particle size is decreased in the quantum-size regime; and use of a simple quantum mechanical model to calculate the particle size from the absorption onset measured for CdS.

  8. Toxicity of quantum dots and cadmium salt to Caenorhabditis elegans after multigenerational exposure.

    Science.gov (United States)

    Contreras, Elizabeth Q; Cho, Minjung; Zhu, Huiguang; Puppala, Hema L; Escalera, Gabriela; Zhong, Weiwei; Colvin, Vicki L

    2013-01-15

    To fully understand the biological and environmental impacts of nanomaterials requires studies that address both sublethal end points and multigenerational effects. Here, we use a nematode to examine these issues as they relate to exposure to two different types of quantum dots, core (CdSe) and core-shell (CdSe/ZnS), and to compare the effect to those observed after cadmium salt exposures. The strong fluorescence of the core-shell QDs allowed for the direct visualization of the materials in the digestive track within a few hours of exposure. Multiple end points, including both developmental and locomotive, were examined at QD exposures of low (10 mg/L Cd), medium (50 mg/L Cd), and high concentrations (100 mg/L Cd). While the core-shell QDs showed no effect on fitness (lifespan, fertility, growth, and three parameters of motility behavior), the core QDs caused acute effects similar to those found for cadmium salts, suggesting that biological effects may be attributed to cadmium leaching from the more soluble QDs. Over multiple generations, we commonly found that for lower life-cycle exposures to core QDs the parents response was generally a poor predictor of the effects on progeny. At the highest concentrations, however, biological effects found for the first generation were commonly similar in magnitude to those found in future generations.

  9. Synthesis of cadmium telluride quantum wires and the similarity of their band gaps to those of equidiameter cadmium telluride quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin-Wang; Sun, Jianwei; Wang, Lin-Wang; Buhro, William E.

    2008-07-11

    High-quality colloidal CdTe quantum wires having purposefully controlled diameters in the range of 5-11 nm are grown by the solution-liquid-solid (SLS) method, using Bi-nanoparticle catalysts, cadmium octadecylphosphonate and trioctylphosphine telluride as precursors, and a TOPO solvent. The wires adopt the wurtzite structure, and grow along the [002] direction (parallel to the c axis). The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to the experimental results for high-quality CdTe quantum dots. In contrast to the predictions of an effective-mass approximation, particle-in-a-box model, and previous experimental results from CdSe and InP dot-wire comparisons, the band gaps of CdTe dots and wires of like diameter are found to be experimentally indistinguishable. The present results are analyzed using density functional theory under the local-density approximation by implementing a charge-patching method. The higher-level theoretical analysis finds the general existence of a threshold diameter, above which dot and wire band gaps converge. The origin and magnitude of this threshold diameter is discussed.

  10. Photoluminescence properties of cadmium-selenide quantum dots embedded in a liquid-crystal polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tselikov, G. I., E-mail: gleb@vega.phys.msu.ru; Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation); Plenge, J.; Ruehl, E. [Free University of Berlin, Institute of Chemistry and Biochemistry (Germany); Shatalova, A. M.; Shandryuk, G. A.; Merekalov, A. S.; Tal' roze, R. V. [Russian Academy of Sciences, Topchiev Institute of Petrochemical Synthesis (Russian Federation)

    2013-05-15

    The photoluminescence properties of cadmium-selenide (CdSe) quantum dots with an average size of {approx}3 nm, embedded in a liquid-crystal polymer matrix are studied. It was found that an increase in the quantum-dot concentration results in modification of the intrinsic (exciton) photoluminescence spectrum in the range 500-600 nm and a nonmonotonic change in its intensity. Time-resolved measurements show the biexponential decay of the photoluminescence intensity with various ratios of fast and slow components depending on the quantum-dot concentration. In this case, the characteristic lifetimes of exciton photoluminescence are 5-10 and 35-50 ns for the fast and slow components, respectively, which is much shorter than the times for colloidal CdSe quantum dots of the same size. The observed features of the photoluminescence spectra and kinetics are explained by the effects of light reabsorption, energy transfer from quantum dots to the liquid-crystal polymer matrix, and the effect of the electronic states at the CdSe/(liquid crystal) interface.

  11. Effect of capping agents on optical and antibacterial properties of cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Deepika; Rakesh Dhar; Suman Singh; Atul Kumar

    2015-09-01

    Cadmium selenide quantum dots (CdSe QDs) were synthesized in aqueous phase by the freezing temperature injection technique using different capping agents (viz. thioglycolic acid, 1-thioglycerol, L-cysteine). Absorption spectra of CdSe QDs exhibited a blue shift as compared to its bulk counterpart, which is an indication of quantum confinement effect. The photoluminescence spectra of CdSe QDs confirmed that the particles are poly-dispersed and possess enhanced luminescent property, depending upon the chemical nature of capping agents. The QDs have been characterized by Fourier-transform infrared spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. Further, antimicrobial activity of as-prepared QDs has also been investigated using the disk diffusion method.

  12. Cadmium-free quantum dots as time-gated bioimaging probes in highly-autofluorescent human breast cancer cells.

    Science.gov (United States)

    Mandal, Gopa; Darragh, Molly; Wang, Y Andrew; Heyes, Colin D

    2013-01-21

    We report cadmium-free, biocompatible (Zn)CuInS(2) quantum dots with long fluorescence lifetimes as superior bioimaging probes using time-gated detection to suppress cell autofluorescence and improve the signal : background ratio by an order of magnitude. These results will be important for developing non-toxic fluorescence imaging probes for ultrasensitive biomedical diagnostics.

  13. Direct Synthesis of Novel and Reactive Sulfide-modified Nano Iron through Nanoparticle Seeding for Improved Cadmium-Contaminated Water Treatment

    Science.gov (United States)

    Su, Yiming; Adeleye, Adeyemi S.; Huang, Yuxiong; Zhou, Xuefei; Keller, Arturo A.; Zhang, Yalei

    2016-04-01

    Magnetic sulfide-modified nanoscale zerovalent iron (S-nZVI) is of great technical and scientific interest because of its promising application in groundwater remediation, although its synthesis is still a challenge. We develop a new nanoparticle seeding method to obtain a novel and reactive nanohybrid, which contains an Fe(0) core covered by a highly sulfidized layer under high extent of sulfidation. Syntheses monitoring experiments show that seeding accelerates the reduction rate from Fe2+ to Fe0 by 19%. X-ray adsorption near edge structure (XANES) spectroscopy and extended X-ray absorption fine structure analyses demonstrate the hexahedral Fe-Fe bond (2.45 and 2.83 Å) formation through breaking down of the 1.99 Å Fe-O bond both in crystalline and amorphous iron oxide. The XANES analysis also shows 24.2% (wt%) of FeS with bond length of 2.4 Å in final nanohybrid. Both X-ray diffraction and Mössbauer analyses further confirm that increased nanoparticle seeding results in formation of more Fe0 crystals. Nano-SiO2 seeding brings down the size of single Fe0 grain from 32.4 nm to 18.7 nm, enhances final Fe0 content from 5.9% to 55.6%, and increases magnetization from 4.7 to 65.5 emu/g. The synthesized nanohybrid has high cadmium removal capacity and holds promising prospects for treatment of metal-contaminated water.

  14. Tunable White Fluorescent Copper Gallium Sulfide Quantum Dots Enabled by Mn Doping.

    Science.gov (United States)

    Jo, Dae-Yeon; Kim, Daekyoung; Kim, Jong-Hoon; Chae, Heeyeop; Seo, Hyo Jin; Do, Young Rag; Yang, Heesun

    2016-05-18

    Fluorescence of semiconductor quantum dots (QDs) can be tuned by engineering the band gap via size and composition control and further doping them with impurity ions. Targeting on highly bright white-emissive I-III-VI -type copper gallium sulfide (Cu-Ga-S, CGS) host QDs with the entire visible spectral coverage of blue to red, herein, Mn(2+) ion doping, through surface adsorption and lattice diffusion is fulfilled. Upon doping a distinct Mn emission from (4)T1-(6)A1 transition successfully appears in white photoluminescence (PL) of undoped CGS/ZnS core/shell QDs and with varying Mn concentration a systematic white spectral evolution of CGS:Mn/ZnS QDs is achievable with high PL quantum yield retained. The origins of white PL of CGS:Mn/ZnS QDs that is well decomposed into three emission bands are appropriately assigned. The resulting single-phased, doped QDs are then employed as near-UV-to-white down converters for the fabrication of white light-emitting diodes (LEDs). Electroluminescent properties of white QD-LEDs depending on Mn concentration of CGS:Mn/ZnS QDs and forward current are also discussed in detail.

  15. A simple route for making surfactant free lead sulfide (PbS) quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Firoz; Kumar, Neetesh; Dutta, Viresh, E-mail: vdutta@ces.iitd.ac.in

    2015-05-15

    Highlights: • Surfactant free PbS NCs were successfully synthesised using CoSP technique. • The technique eliminates the requirements of washing to remove the ligands. • Grinding using mortar and pestle creates well separated PbS QDs. • Surfactant free PbS NCs are stable and do not show any degradation with time. - Abstract: An efficient, cost effective and less time consuming method suitable for mass production of surfactant free quantum dots (QDs) of lead sulfide (PbS) is reported. PbS nanocrystals (NCs) are first synthesised by continuous spray pyrolysis (CoSP) technique and de-agglomeration into PbS quantum dots (QDs) is achieved by vigorous mechanical grinding using mortar and pestle. Lead acetate and thiourea were used as the precursor materials for preparation of surfactant free PbS NCs. The broadening in XRD peaks of ground NCs as compared to as synthesized PbS NCs clearly indicated the reduction in particle size to be QDs of PbS. The TEM images also showed that ground PbS NCs were nearly spherical in shape having an average diameter in the range of 4–6 nm. The shift in optical gap from 0.41 eV to 1.47 eV supported the QD formation.

  16. Ternary spinel cadmium stannate, cadmium indate, and zinc stannate and binary tin oxide and indium oxide transparent conducting oxides as front contact materials for cadmium sulfide/cadmium tellurium photovoltaic devices

    Science.gov (United States)

    Mamazza, Robert, Jr.

    Transparent conducting oxides (TCO's) of Cd2SnO 4 (cadmium stannate), CdIn2O4 (cadmium indate), and Zn2SnO4 (zinc stannate) thin films were investigated from a materials and applications point of view through. All films were deposited by co-sputtering using either binary oxide or metallic (reactive sputtering) targets. The film properties were investigated as a function of film composition and stoichiometry. The effect of process parameters such as deposition temperatures, and post-deposition heat treatments on the structural and electro-optical properties of the films were also investigated extensively. All as-deposited films were found to be amorphous independent of substrate deposition temperature. The electro-optical and crystallographic properties were heavily dependant on the post deposition heat treatments. Cd2SnO4, Zn 2SnO4, and CdIn2O4 all produced highly transparent films with average transmission values (400--900 nm range) of 92%, 93%, and 90%, respectively. Cd2SnO4 and CdIn 2O4 were highly conductive with resistivity values as low as 2.01 x 10-4 O-cm and 2.90 x 10 -4 O-cm, respectively. Conversely, Zn2SnO 4 was not able to produce highly conductive films, with the lowest resistivity being 4.3 x 10-3 O-cm. CdTe solar cells were fabricated using al the above materials as front contacts or as high-ρ layers in bi-layer structures. All cells were of the superstrate configuration: Low-ρ TCO/high-ρ TCO/CdS/CdTe/Back contact. Only the TCO layers were varied; the remainder of the device was held constant. In most cases the inclusion of a high-ρ TCO layer was found to improve solar cell performance, especially in regard to the open circuit voltage. Cd2SnO4 was the exception. The incorporation of Zn2SnO4 as a high-ρ layer enabled a greatest current collection from high energy wavelengths through an apparent thinning effect on the CdS. This increased the overall short circuit current density to values in excess of 24.9 mA/cm2. The standard device consisted of

  17. Toxicity of quantum dots and cadmium to rainbow trout (Oncorhynchus mykiss in early ontogenesis

    Directory of Open Access Journals (Sweden)

    Živilė Cibulskaitė

    2015-11-01

    Full Text Available The aim of the study was to investigate toxic effects of CdSe/ZnS-COOH quantum dots (QD and cadmium (Cd on biological parameters of rainbow trout (Oncorhychus mykiss in its early stages of development (embryos and larvae. It was found that short-term (24-, 96-hour exposure to sublethal concentrations of QD and Cd increased mortality of embryos and larvae, disturbed function of the cardio-respiratory system (gill ventilation frequency, heart rate and affected behavioural responses (individuals making nests in rainbow trout larvae. The results indicated that toxic effects of QD and Cd on rainbow trout larvae depended on the type of chemical substance, affected stage of development and exposure duration. Comparative studies of the effects of QD and Cd on rainbow trout in early stages of development showed that larvae were more sensitive to Cd and QD as compared to embryos. It was suggested that the chorion envelopes of eggs surround and protect the embryo from QD and Cd. Cadmium was more toxic to larvae than QD. Longer exposure (96-hour of QD and Cd induced more remarkable changes in test-parameters. This original study requires more investigations evaluating the mechanism of toxicity of QD to fish.

  18. New route for preparation of luminescent mercaptoethanoate capped cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Manoj E Wankhede; Shaukatali N Inamdar; Aparna Deshpande; Aniket R Thete; Renu Pasricha; Sulabha K Kulkarni; Santosh K Haram

    2008-06-01

    We report a synthesis of cadmium selenide quantum dots (Q-CdSe) by refluxing a mixture of cadmium acetate, selenium powder, sodium sulfite and 2-mercaptoethanol in N,N′-dimethyl formamide (DMF)/water solution. X-ray and electron diffractions suggest the formation of hexagonal phase of size quantized CdSe. Based on TEM analysis, the formation of nanoparticles with an average diameter of 3.5 ± 0.5 nm is inferred. Their sols in DMF and dimethyl sulphoxide (DMSO) gave characteristic absorption peaks at 300 nm and 327 nm, which is attributed to the formation of high quality, size quantized CdSe particles. Extracted particles from the sol were readily redispersed in DMF and DMSO, which were diluted further with water without losing their optical and colloidal properties. FTIR spectroscopy suggested the formation of 2-mercaptoethanol thiolate on the particle surface, with free –OH groups available for linkage. Sols in DMSO and their solutions in water displayed an intense photoluminescence (PL).

  19. Improved performance of silicon nanowire/cadmium telluride quantum dots/organic hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Zhaoyun [National Laboratory of Solid State Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu Province (China); Xu, Ling, E-mail: xuling@nju.edu.cn [National Laboratory of Solid State Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Renqi; Xue, Zhaoguo; Wang, Hongyu; Xu, Jun; Yu, Yao; Su, Weining; Ma, Zhongyuan; Chen, Kunji [National Laboratory of Solid State Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2015-04-15

    Highlights: • We introduce an intermediate cadmium telluride quantum dots (CdTe QDs) layer between the organic with silicon nanowires of hybrid solar cells as a down-shifting layer. • The hybrid solar cell got the maximum short circuit current density of 33.5 mA/cm{sup 2}, getting an increase of 15.1% comparing to solar cell without CdTe QDs. • The PCE of the hybrid solar cells with CdTe QDs layer increases 28.8%. - Abstract: We fabricated silicon nanowire/cadmium telluride quantum dots (CdTe QDs)/organic hybrid solar cells and investigated their structure and electrical properties. Transmission electron microscope revealed that CdTe QDs were uniformly distributed on the surface of the silicon nanowires, which made PEDOT:PSS easily filled the space between SiNWs. The current density–voltage (J–V) characteristics of hybrid solar cells were investigated both in dark and under illumination. The result shows that the performance of the hybrid solar cells with CdTe QDs layer has an obvious improvement. The optimal short-circuit current density (J{sub sc}) of solar cells with CdTe QDs layer can reach 33.5 mA/cm{sup 2}. Compared with the solar cells without CdTe QDs, J{sub sc} has an increase of 15.1%. Power conversion efficiency of solar cells also increases by 28.8%. The enhanced performance of the hybrid solar cells with CdTe QDs layers are ascribed to down-shifting effect of CdTe QDs and the modification of the silicon nanowires surface with CdTe QDs. The result of our experiments suggests that hybrid solar cells with CdTe QDs modified are promising candidates for solar cell application.

  20. Lead Sulfide Cathode for Quantum Dot Solar Cells: Electrosynthesis and Characterization

    Science.gov (United States)

    Van Le, Nghiem; Nguyen, Hoang Thai; Le, Hai Viet; Nguyen, Thoa Thi Phuong

    2017-01-01

    Deposition of lead sulfide (PbS) nanocrystalline thin films onto conducting fluorine-doped tin oxide (FTO) glass has been performed by cyclic voltammetry (CV) in 1.5 mM solution of lead nitrate and sodium thiosulfate at 100 mV s-1 scan rate in the potential range of -1.0 V to 0.0 V versus saturated calomel electrode. X-ray diffraction analysis and scanning electron microscopy revealed formation of cubic PbS crystals with size of 100 nm to 150 nm after 50 cycles. High electrocatalytic activity of the synthesized PbS film for the S2-/S n 2- redox couple, used as a mediator for quantum dot solar cells (QDSCs), was demonstrated by electrochemical impedance spectroscopy and CV measurements. The prepared PbS/FTO was used as a counterelectrode to fabricate PbS-QDSCs with a photoanode consisting of CdS/CdSe quantum dots adsorbed on mesoporous TiO2 film and a polysulfide solution electrolyte. The performance of the PbS-QDSC was compared with a QDSC with a platinum counterelectrode (Pt-QDSC). It was found that, using the same fabrication conditions, the performance of the PbS-QDSC was better than that of the Pt-QDSC. At 1 sun (100 mW cm-2) simulated light, average energy conversion efficiency of 2.14%, short-circuit current of 9.22 mA cm-2, open-circuit potential of 0.50 V, and fill factor of 0.47 were achieved by the fabricated PbS-QDSC.

  1. Lead Sulfide Cathode for Quantum Dot Solar Cells: Electrosynthesis and Characterization

    Science.gov (United States)

    Van Le, Nghiem; Nguyen, Hoang Thai; Le, Hai Viet; Nguyen, Thoa Thi Phuong

    2016-08-01

    Deposition of lead sulfide (PbS) nanocrystalline thin films onto conducting fluorine-doped tin oxide (FTO) glass has been performed by cyclic voltammetry (CV) in 1.5 mM solution of lead nitrate and sodium thiosulfate at 100 mV s-1 scan rate in the potential range of -1.0 V to 0.0 V versus saturated calomel electrode. X-ray diffraction analysis and scanning electron microscopy revealed formation of cubic PbS crystals with size of 100 nm to 150 nm after 50 cycles. High electrocatalytic activity of the synthesized PbS film for the S2-/S{/n 2-} redox couple, used as a mediator for quantum dot solar cells (QDSCs), was demonstrated by electrochemical impedance spectroscopy and CV measurements. The prepared PbS/FTO was used as a counterelectrode to fabricate PbS-QDSCs with a photoanode consisting of CdS/CdSe quantum dots adsorbed on mesoporous TiO2 film and a polysulfide solution electrolyte. The performance of the PbS-QDSC was compared with a QDSC with a platinum counterelectrode (Pt-QDSC). It was found that, using the same fabrication conditions, the performance of the PbS-QDSC was better than that of the Pt-QDSC. At 1 sun (100 mW cm-2) simulated light, average energy conversion efficiency of 2.14%, short-circuit current of 9.22 mA cm-2, open-circuit potential of 0.50 V, and fill factor of 0.47 were achieved by the fabricated PbS-QDSC.

  2. Synthesis and structural characterization of magnetic cadmium sulfide-cobalt ferrite nanocomposite, and study of its activity for dyes degradation under ultrasound

    Science.gov (United States)

    Farhadi, Saeed; Siadatnasab, Firouzeh

    2016-11-01

    Cadmium sulfide-cobalt ferrite (CdS/CFO) nanocomposite was easily synthesized by one-step hydrothermal decomposition of cadmium diethyldithiocarbamate complex on the CoFe2O4 nanoparticles at 200 °C. Spectroscopic techniques of powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and magnetic measurements were applied for characterizing the structure and morphology of the product. The results of FT-IR, XRD and EDX indicated that the CdS/CFO was highly pure. SEM and TEM results revealed that the CdS/CFO nanocomposite was formed from nearly uniform and sphere-like nanoparticles with the size of approximately 20 nm. The UV-vis absorption spectrum of the CdS/CFO nanocomposite showed the band gap of 2.21 eV, which made it suitable for sono-/photo catalytic purposes. By using the obtained CdS/CFO nanocomposite, an ultrasound-assisted advanced oxidation process (AOP) has been developed for catalytic degradation of methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO)) in the presence of H2O2 as a green oxidant. CdS/CFO nanocomposite exhibited excellent sonocatalytic activity, so that, dyes were completely degraded in less than 10 min. The influences of crucial factors such as the H2O2 amount and catalyst dosage on the degradation efficiency were evaluated. The as-prepared CdS/CFO nanocomposite exhibited higher catalytic activity than pure CdS nanoparticles. Moreover, the magnetic property of CoFe2O4 made the nanocomposite recyclable.

  3. Meta-analysis of cellular toxicity for cadmium-containing quantum dots

    Science.gov (United States)

    Oh, Eunkeu; Liu, Rong; Nel, Andre; Gemill, Kelly Boeneman; Bilal, Muhammad; Cohen, Yoram; Medintz, Igor L.

    2016-05-01

    Understanding the relationships between the physicochemical properties of engineered nanomaterials and their toxicity is critical for environmental and health risk analysis. However, this task is confounded by material diversity, heterogeneity of published data and limited sampling within individual studies. Here, we present an approach for analysing and extracting pertinent knowledge from published studies focusing on the cellular toxicity of cadmium-containing semiconductor quantum dots. From 307 publications, we obtain 1,741 cell viability-related data samples, each with 24 qualitative and quantitative attributes describing the material properties and experimental conditions. Using random forest regression models to analyse the data, we show that toxicity is closely correlated with quantum dot surface properties (including shell, ligand and surface modifications), diameter, assay type and exposure time. Our approach of integrating quantitative and categorical data provides a roadmap for interrogating the wide-ranging toxicity data in the literature and suggests that meta-analysis can help develop methods for predicting the toxicity of engineered nanomaterials.

  4. Toxicological impact of cadmium-based quantum dots towards aquatic biota: Effect of natural sunlight exposure.

    Science.gov (United States)

    Silva, B F; Andreani, T; Gavina, A; Vieira, M N; Pereira, C M; Rocha-Santos, T; Pereira, R

    2016-07-01

    Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same aggregation behaviour after sunlight exposure was observed for bare QDs. These results further emphasize that the shell of QDs seems to make them less harmful to aquatic biota, both under standard environmental conditions and after the exposure to a relevant abiotic factor like sunlight.

  5. Near-infrared luminescence of cadmium pigments: in situ identification and mapping in paintings.

    Science.gov (United States)

    Thoury, Mathieu; Delaney, John K; Rie, E René de la; Palmer, Michael; Morales, Kathryn; Krueger, Jay

    2011-08-01

    A comprehensive study of the luminescence properties of cadmium pigments was undertaken to determine whether these properties could be used for in situ identification and mapping of the pigments in paintings. Cadmium pigments are semiconductors that show band edge luminescence in the visible range and deep trap luminescence in the red/infrared range. Emission maxima, quantum yields, and excitation spectra from the band edge and deep trap emissions were studied for sixty commercial cadmium pigments that span the color range from yellow to red (reflectance transition 470 to 660 nm). For paints containing cadmium pigments, luminescence from deep traps was more readily observable than that from the band edge, although the yield varied widely from zero to around 4.5%. Optimal excitation for emission is found to be in the visible for both pigments in powder form and mixed with a medium. The maxima of the deep trap emission shift with the band gap energy, providing a potentially useful way to assign pigment type even when used in pigment mixtures. The usefulness of the results of the study on mockups was demonstrated by the mapping of cadmium pigments of different hues with the aid of calibrated luminescence imaging spectroscopy in a painting by Edward Steichen, entitled Study for 'Le Tournesol' (1920). Analysis of the luminescence image cube reveals at least six unique spectral components, associated with emission from white pigments, paint binder, and cadmium red and yellow pigments. The results were compared with those from X-ray fluorescence spectrometry (XRF) and fiber-optic reflection spectroscopy (FORS) and the results obtained on paint samples containing cadmium pigments. These results show that, when present, the emission from traps can be used as an analytical tool to identify cadmium pigments, to distinguish among cadmium sulfide, cadmium zinc sulfide, and cadmium sulfoselenide, and to map cadmium pigments, even in mixtures.

  6. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    Science.gov (United States)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  7. Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism

    Science.gov (United States)

    Yan, Si-Qi; Xing, Rui; Zhou, Yan-Feng; Li, Kai-Le; Su, Yuan-Yuan; Qiu, Jian-Feng; Zhang, Yun-Hu; Zhang, Ke-Qin; He, Yao; Lu, Xiao-Ping; Xu, Shi-Qing

    2016-09-01

    Sexual glands are key sites affected by nanotoxicity, but there is no sensitive assay for measuring reproductive toxicity in animals. The aim of this study was to investigate the toxic effects of cadmium telluride quantum dots (CdTe-QDs) on gonads in a model organism, Bombyx mori. After dorsal vein injection of 0.32 nmol of CdTe-QDs per individual, the QDs passed through the outer membranes of gonads via the generation of ROS in the membranes of spermatocysts and ovarioles, as well as internal germ cells, thereby inducing early germ cell death or malformations via complex mechanisms related to apoptosis and autophagy through mitochondrial and lysosomal pathways. Histological observations of the gonads and quantitative analyses of germ cell development showed that the reproductive toxicity was characterized by obvious male sensitivity. Exposure to QDs in the early stage of males had severe adverse effects on the quantity and quality of sperm, which was the main reason for the occurrence of unfertilized eggs. Ala- or Gly-conjugated QDs could reduce the nanotoxicity of CdTe-QDs during germ cell development and fertilization of their offspring. The results demonstrate that males are preferable models for evaluating the reproductive toxicity of QDs in combined in vivo/in vitro investigations.

  8. Inhibition of autophagy contributes to the toxicity of cadmium telluride quantum dots in Saccharomyces cerevisiae.

    Science.gov (United States)

    Fan, Junpeng; Shao, Ming; Lai, Lu; Liu, Yi; Xie, Zhixiong

    2016-01-01

    Cadmium telluride quantum dots (CdTe QDs) are used as near-infrared probes in biologic and medical applications, but their cytological effects and mechanism of potential toxicity are still unclear. In this study, we evaluated the toxicity of CdTe QDs of different sizes and investigated their mechanism of toxicity in the yeast Saccharomyces cerevisiae. A growth inhibition assay revealed that orange-emitting CdTe (O-CdTe) QDs (half inhibitory concentration [IC50] =59.44±12.02 nmol/L) were more toxic than green-emitting CdTe QDs (IC50 =186.61±19.74 nmol/L) to S. cerevisiae. Further studies on toxicity mechanisms using a transmission electron microscope and green fluorescent protein tagged Atg8 processing assay revealed that O-CdTe QDs could partially inhibit autophagy at a late stage, which differs from the results reported in mammalian cells. Moreover, autophagy inhibited at a late stage by O-CdTe QDs could be partially recovered by enhancing autophagy with rapamycin (an autophagy activator), combined with an increased number of living cells. These results indicate that inhibition of autophagy acts as a toxicity mechanism of CdTe QDs in S. cerevisiae. This work reports a novel toxicity mechanism of CdTe QDs in yeast and provides valuable information on the effect of CdTe QDs on the processes of living cells.

  9. Cytotoxicity of cadmium-containing quantum dots based on a study using a microfluidic chip

    Science.gov (United States)

    Zheng, Xiannuo; Tian, Jing; Weng, Lixing; Wu, Lei; Jin, Qinghui; Zhao, Jianlong; Wang, Lianhui

    2012-02-01

    There is a lack of reliable nanotoxicity assays available for monitoring and quantifying multiple cellular events in cultured cells. In this study, we used a microfluidic chip to systematically investigate the cytotoxicity of three kinds of well-characterized cadmium-containing quantum dots (QDs) with the same core but different shell structures, including CdTe core QDs, CdTe/CdS core-shell QDs, and CdTe/CdS/ZnS core-shell-shell QDs, in HEK293 cells. Using the microfluidic chip combined with fluorescence microscopy, multiple QD-induced cellular events including cell morphology, viability, proliferation, and QD uptake were simultaneously analysed. The three kinds of QDs showed significantly different cytotoxicities. The CdTe QDs, which are highly toxic to HEK293 cells, resulted in remarkable cellular and nuclear morphological changes, a dose-dependent decrease in cell viability, and strong inhibition of cell proliferation; the CdTe/CdS QDs were moderately toxic but did not significantly affect the proliferation of HEK293 cells; while the CdTe/CdS/ZnS QDs had no detectable influence on cytotoxicity with respect to cell morphology, viability, and proliferation. Our data indicated that QD cytotoxicity was closely related to their surface structures and specific physicochemical properties. This study also demonstrated that the microfluidic chip could serve as a powerful tool to systematically evaluate the cytotoxicity of nanoparticles in multiple cellular events.

  10. Immunocytotoxicity, cytogenotoxicity and genotoxicity of cadmium-based quantum dots in the marine mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Rocha, Thiago Lopes; Gomes, Tânia; Cardoso, Cátia; Letendre, Julie; Pinheiro, José Paulo; Sousa, Vânia Serrão; Teixeira, Margarida Ribau; Bebianno, Maria João

    2014-10-01

    There is an increased use of Quantum Dot (QDs) in biological and biomedical applications, but little is known about their marine ecotoxicology. So, the aim of this study was to investigate the possible immunocytotoxic, cytogenotoxic and genotoxic effects of cadmium telluride QDs (CdTe QDs) on the marine mussel Mytilus galloprovincialis. Mussels were exposed to 10 μg L(-1) of CdTe QDs or to soluble Cd [Cd(NO3)2] for 14 days and Cd accumulation, immunocytotoxicity [hemocyte density, cell viability, lysosomal membrane stability (LMS), differential cell counts (DCC)], cytogenotoxicity (micronucleus test and nuclear abnormalities assay) and genotoxicity (comet assay) were analyzed. Results show that in vivo exposure to QDs, Cd is accumulated in mussel soft tissues and hemolymph and induce immunotoxic effects mediated by a decrease in LMS, changes in DCC, as well as genotoxicity (DNA damage). However, QDs do not induce significant changes in hemocytes density, cell viability and cytogenetic parameters in opposition to Cd(2+). Soluble Cd is the most cytotoxic and cytogenotoxic form on Mytilus hemocytes due to a higher accumulation of Cd in tissues. Results indicate that immunotoxicity and genotoxicity of CdTe QDs and Cd(2+) are mediated by different modes of action and show that Mytilus hemocytes are important targets for in vivo QDs toxicity.

  11. Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism

    Science.gov (United States)

    Yan, Si-Qi; Xing, Rui; Zhou, Yan-Feng; Li, Kai-Le; Su, Yuan-Yuan; Qiu, Jian-Feng; Zhang, Yun-Hu; Zhang, Ke-Qin; He, Yao; Lu, Xiao-Ping; Xu, Shi-Qing

    2016-01-01

    Sexual glands are key sites affected by nanotoxicity, but there is no sensitive assay for measuring reproductive toxicity in animals. The aim of this study was to investigate the toxic effects of cadmium telluride quantum dots (CdTe-QDs) on gonads in a model organism, Bombyx mori. After dorsal vein injection of 0.32 nmol of CdTe-QDs per individual, the QDs passed through the outer membranes of gonads via the generation of ROS in the membranes of spermatocysts and ovarioles, as well as internal germ cells, thereby inducing early germ cell death or malformations via complex mechanisms related to apoptosis and autophagy through mitochondrial and lysosomal pathways. Histological observations of the gonads and quantitative analyses of germ cell development showed that the reproductive toxicity was characterized by obvious male sensitivity. Exposure to QDs in the early stage of males had severe adverse effects on the quantity and quality of sperm, which was the main reason for the occurrence of unfertilized eggs. Ala- or Gly-conjugated QDs could reduce the nanotoxicity of CdTe-QDs during germ cell development and fertilization of their offspring. The results demonstrate that males are preferable models for evaluating the reproductive toxicity of QDs in combined in vivo/in vitro investigations. PMID:27669995

  12. 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.

  13. Toxicological impact of cadmium-based quantum dots towards aquatic biota: Effect of natural sunlight exposure

    Energy Technology Data Exchange (ETDEWEB)

    Silva, B.F. [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Andreani, T. [Centro de Investigação em Química da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CITAB − Centre for Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes e Alto Douro, UTAD, Vila Real (Portugal); Gavina, A., E-mail: anacsgavina@gmail.com [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Vieira, M.N. [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Pereira, C.M. [Centro de Investigação em Química da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Rocha-Santos, T. [Department of Chemistry and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); and others

    2016-07-15

    Highlights: • Under sunlight exposure, all QDs form particle aggregates in the different media. • CdSeS/ZnS QDs showed lower toxic effects to V. fischeri before sunlight exposure. • Sunlight exposure decreased the toxicity of CdS 480 in all organisms. • Sunlight exposure increased the toxicity of CdS 380 QDs for D. magna. • Shell of QDs seemed to make them less harmful to aquatic organisms. - Abstract: Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same

  14. Controlling electron beam-induced structure modifications and cation exchange in cadmium sulfide–copper sulfide heterostructured nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Haimei [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sadtler, Bryce; Habenicht, Carsten [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Freitag, Bert [FEI Company, P.O. Box 80066, KA 5600 Eindhoven (Netherlands); Alivisatos, A. Paul [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Kisielowski, Christian, E-mail: CFKisielowski@lbl.gov [National Center for Electron Microcopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Joint Center for Artificial Photosynthesis, Berkeley, CA 94720 (United States)

    2013-11-15

    The atomic structure and interfaces of CdS/Cu{sub 2}S heterostructured nanorods are investigated with the aberration-corrected TEAM 0.5 electron microscope operated at 80 kV and 300 kV applying in-line holography and complementary techniques. Cu{sub 2}S exhibits a low-chalcocite structure in pristine CdS/Cu{sub 2}S nanorods. Under electron beam irradiation the Cu{sub 2}S phase transforms into a high-chalcocite phase while the CdS phase maintains its wurtzite structure. Time-resolved experiments reveal that Cu{sup +}–Cd{sup 2+} cation exchange at the CdS/Cu{sub 2}S interfaces is stimulated by the electron beam and proceeds within an undisturbed and coherent sulfur sub-lattice. A variation of the electron beam current provides an efficient way to control and exploit such irreversible solid-state chemical processes that provide unique information about system dynamics at the atomic scale. Specifically, we show that the electron beam-induced copper–cadmium exchange is site specific and anisotropic. A resulting displacement of the CdS/Cu{sub 2}S interfaces caused by beam-induced cation interdiffusion equals within a factor of 3–10 previously reported Cu diffusion length measurements in heterostructured CdS/Cu{sub 2}S thin film solar cells with an activation energy of 0.96 eV. - Highlights: • Heterostructured nanorods were investigated at atomic resolution showing that they are free of extended defects. • Beam–sample interactions are controlled by current and voltage variations to provide pristine crystal structures. • Beam-induced migration of heterointerfaces are measured time-resolved and compared with Cu diffusion coefficients. • Beam–sample interaction overwrite possible signal improvements that can be expected by sample cooling.

  15. Chemical Control of Lead Sulfide Quantum Dot Shape, Self-Assembly, and Charge Transport

    Science.gov (United States)

    McPhail, Martin R.

    Lead(II) sulfide quantum dots (PbS QDs) are a promising excitonic material for numerous application that require that control of fluxes of charge and energy at nanoscale interfaces, such as solar energy conversion, photo- and electrocatalysis, light emitting diodes, chemical sensing, single-electron logic elements, field effect transistors, and photovoltaics. PbS QDs are particularly suitable for photonics applications because they exhibit size-tunable band-edge absorption and fluorescence across the entire near-infrared spectrum, undergo efficient multi-exciton generation, exhibit a long radiative lifetime, and possess an eight-fold degenerate ground-state. The effective integration of PbS QDs into these applications requires a thorough understanding of how to control their synthesis, self-assembly, and charge transport phenomena. In this document, I describe a series of experiments to elucidate three levels of chemical control on the emergent properties of PbS QDs: (1) the role of surface chemistry in controlling PbS QD shape during solvothermal synthesis, (2) the role of QD shape and ligand functionalization in self-assembly at a liquid-air interface, and (3) the role of QD packing structure on steady-state conductivity and transient current dynamics. At the synthetic level (1), I show that the final shape and surface chemistry of PbS QDs is highly sensitive to the formation of organosulfur byproducts by commonly used sulfur reagents. The insight into PbS QD growth gained from this work is then developed to controllably tune PbS QD shape from cubic to octahedral to hexapodal while maintaining QD size. At the following level of QD self-assembly (2), I show how QD size and shape dictate packing geometry in extended 2D arrays and how this packing can be controllably interrupted in mixed monolayers. I also study the role of ligand structure on the reorganization of QD arrays at a liquid-air interface and find that the specific packing defects in QD arrays vary

  16. A study on the connection and physical properties of Cadmium selenide nanoparticles and zinc sulfide nanoparticles made by ultrasonic method

    Directory of Open Access Journals (Sweden)

    Shabnam Taheriniya

    2016-04-01

    Full Text Available Ultrasonic waves are called to hordes of mechanical waves that their oscillation frequency exceeds from human hearing range (20 Hz- 20 KHz. These waves have various applications due to their properties; ultrasonic frequency acoustic waves (16 KHz to 2 MHz are used for curing and ultrasonic process parameters (amplitude, frequency and power can be controlled properly. Ultrasonic process in fluids is followed by acoustic cavitation phenomenon (cavitation. Indeed, acoustic cavitation refers to the formation of bubbles (pores due to the rapid drop in water caused by passing the sound waves through it. In this research, an action was made to produce CdSe and ZnS nanoparticles using this method. Ultimately, ZnS quantum dots and ZnS nanoparticles were connected to each other using a coupling agent copolymer (PEG-PCA. The optical properties of this nanoparticle were examined by using X-ray diffraction and evaluated using UV-Visblel range of coupling effect.

  17. Visible-light driven photocatalytic activity of β-indium sulfide (In2S3) quantum dots embedded in Nafion matrix

    Science.gov (United States)

    Sumi, R.; Warrier, Anita R.; Vijayan, C.

    2014-03-01

    We report on the visible-light-driven photocatalytic activity of highly stable β-indium sulfide (In2S3) quantum dots embedded in Nafion matrix. β-indium sulfide (In2S3) quantum dots (6-10 nm) embedded in Nafion matrix with strong quantum confinement were synthesized by a simple chemical route. The UV-Vis absorption spectrum shows a large blue shift (˜1 eV) which can be controlled by the reaction temperature and time. Strong broadband photoluminescence is observed in the blue, green and red regions of the emission spectrum with variation in particle size and stoichiometry of the quantum dots. Photocatalytic activity measurements show that these hybrid membranes synthesized with equimolar precursors of In and S show paramount photocatalytic activity under visible-light irradiation, with the degradation of Rhodamine-6G dyes up to 95% within 90 min. The photocatalytic membranes are tested for reusable and stable operation.

  18. The influence of ligand type on self-organization and optical properties of cadmium selenide quantum dots

    Science.gov (United States)

    Ushakova, E. V.; Kormilina, T. K.; Burkova, M. A.; Cherevkov, S. A.; Zakharov, V. V.; Turkov, V. K.; Fedorov, A. V.; Baranov, A. V.

    2017-01-01

    A method for successive replacement of organic shells of colloidal cadmium selenide quantum dots (QDs) of different sizes is proposed. It is found that the spectral parameters of QD samples depend on the type of organic shells. It is shown that the structural morphology is independent of the QD size and is determined by the chemical composition of the organic shell. Spectral analysis of the luminescence of QD-based superstructures shows that the luminescence wavelength and intensity strongly depend on the degree of QD surface passivation.

  19. Inhibition of autophagy contributes to the toxicity of cadmium telluride quantum dots in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Fan J

    2016-07-01

    Full Text Available Junpeng Fan,1–4 Ming Shao,1–4 Lu Lai,3–5 Yi Liu,3–5 Zhixiong Xie1–4,6 1College of Life Sciences, Wuhan University, 2Hubei Provincial Cooperative Innovation Center of Industrial Fermentation,3State Key Laboratory of Virology, 4Key Laboratory of Analytical Chemistry for Biology and Medicine (MOE, 5College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 6School of Life Science and Technology, Hubei Engineering University, Xiaogan, People’s Republic of China Abstract: Cadmium telluride quantum dots (CdTe QDs are used as near-infrared probes in biologic and medical applications, but their cytological effects and mechanism of potential toxicity are still unclear. In this study, we evaluated the toxicity of CdTe QDs of different sizes and investigated their mechanism of toxicity in the yeast Saccharomyces cerevisiae. A growth inhibition assay revealed that orange-emitting CdTe (O-CdTe QDs (half inhibitory concentration [IC50] =59.44±12.02 nmol/L were more toxic than green-emitting CdTe QDs (IC50 =186.61±19.74 nmol/L to S. cerevisiae. Further studies on toxicity mechanisms using a transmission electron microscope and green fluorescent protein tagged Atg8 processing assay revealed that O-CdTe QDs could partially inhibit autophagy at a late stage, which differs from the results reported in mammalian cells. Moreover, autophagy inhibited at a late stage by O-CdTe QDs could be partially recovered by enhancing autophagy with rapamycin (an autophagy activator, combined with an increased number of living cells. These results indicate that inhibition of autophagy acts as a toxicity mechanism of CdTe QDs in S. cerevisiae. This work reports a novel toxicity mechanism of CdTe QDs in yeast and provides valuable information on the effect of CdTe QDs on the processes of living cells. Keywords: CdTe quantum dots, Saccharomyces cerevisiae, toxicity, autophagy

  20. Cadmium Disrupts the Balance between Hydrogen Peroxide and Superoxide Radical by Regulating Endogenous Hydrogen Sulfide in the Root Tip of Brassica rapa

    Science.gov (United States)

    Lv, Wenjing; Yang, Lifei; Xu, Cunfa; Shi, Zhiqi; Shao, Jinsong; Xian, Ming; Chen, Jian

    2017-01-01

    Cd (cadmium) stress always alters the homeostasis of ROS (reactive oxygen species) including H2O2 (hydrogen sulfide) and O2•– (superoxide radical), leading to the oxidative injury and growth inhibition in plants. In addition to triggering oxidative injury, ROS has been suggested as important regulators modulating root elongation. However, whether and how Cd stress induces the inhibition of root elongation by differentially regulating endogenous H2O2 and O2•–, rather than by inducing oxidative injury, remains elusive. To address these gaps, histochemical, physiological, and biochemical approaches were applied to investigate the mechanism for Cd to fine-tune the balance between H2O2 and O2•– in the root tip of Brassica rapa. Treatment with Cd at 4 and 16 μM significantly inhibited root elongation, while only 16 μM but not 4 μM of Cd induced oxidative injury and cell death in root tip. Fluorescent and pharmaceutical tests suggested that H2O2 and O2•– played negative and positive roles, respectively, in the regulation of root elongation in the presence of Cd (4 μM) or not. Treatment with Cd at 4 μM led to the increase in H2O2 and the decrease in O2•– in root tip, which may be attributed to the up-regulation of Br_UPB1s and the down-regulation of their predicted targets (four peroxidase genes). Cd at 4 μM resulted in the increase in endogenous H2S in root tip by inducing the up-regulation of LCDs and DCDs. Treatment with H2S biosynthesis inhibitor or H2S scavenger significantly blocked Cd (4 μM)-induced increase in endogenous H2S level, coinciding with the recovery of root elongation, the altered balance between H2O2 and O2•–, and the expression of Br_UPB1s and two peroxidase genes. Taken together, it can be proposed that endogenous H2S mediated the phytotoxicity of Cd at low concentration by regulating Br_UPB1s-modulated balance between H2O2 and O2•– in root tip. Such findings shed new light on the regulatory role of endogenous H2S in

  1. Time-dependent toxicity of cadmium telluride quantum dots on liver and kidneys in mice: histopathological changes with elevated free cadmium ions and hydroxyl radicals

    Directory of Open Access Journals (Sweden)

    Wang M

    2016-05-01

    Full Text Available Mengmeng Wang,1,2,* Jilong Wang,1,2,* Hubo Sun,1,2 Sihai Han,3 Shuai Feng,1 Lu Shi,1 Peijun Meng,1,2 Jiayi Li,1,2 Peili Huang,1,2 Zhiwei Sun1,2 1Department of Toxicology and Sanitary Chemistry, School of Public Health, Capital Medical University, 2Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, 3College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, People’s Republic of China *These authors contributed equally to this work Abstract: A complete understanding of the toxicological behavior of quantum dots (QDs in vivo is of great importance and a prerequisite for their application in humans. In contrast with the numerous cytotoxicity studies investigating QDs, only a few in vivo studies of QDs have been reported, and the issue remains controversial. Our study aimed to understand QD-mediated toxicity across different time points and to explore the roles of free cadmium ions (Cd2+ and hydroxyl radicals (·OH in tissue damage. Male ICR mice were administered a single intravenous dose (1.5 µmol/kg of CdTe QDs, and liver and kidney function and morphology were subsequently examined at 1, 7, 14, and 28 days. Furthermore, ·OH production in the tissue was quantified by trapping ·OH with salicylic acid (SA as 2,3-dihydroxybenzoic acid (DHBA and detecting it using a high-performance liquid chromatography fluorescence method. We used the induction of tissue metallothionein levels and 2,3-DHBA:SA ratios as markers for elevated Cd2+ from the degradation of QDs and ·OH generation in the tissue, respectively. Our experimental results revealed that the QD-induced histopathological changes were time-dependent with elevated Cd2+ and ·OH, and could recover after a period of time. The Cd2+ and ·OH exhibited delayed effects in terms of histopathological abnormalities. Histological assessments performed at multiple time points might facilitate the evaluation of the biological safety of

  2. 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.

  3. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    Science.gov (United States)

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M.

    2015-06-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd2+]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate the

  4. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Torres, Marcos R. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Velez, Christian; Zayas, Beatriz [Universidad Metropolitana, ChemTox Laboratory, School of Environmental Affairs (United States); Rivera, Osvaldo [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Arslan, Zikri [Jackson State University, Department of Chemistry (United States); Gonzalez-Vega, Maxine N. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo [University of Puerto Rico, Molecular Science Research Center (United States); Primera-Pedrozo, Oliva M., E-mail: oprimera1@suagm.edu [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States)

    2015-06-15

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd{sup 2+}]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to

  5. The synthesis of quantum size lead sulfide particles in surfactant-based complex fluid media

    Energy Technology Data Exchange (ETDEWEB)

    Ward, A.J.I.; O' Sullivan, E.C.; Rang, Jing Chen; Nedeljkovic, J.; Patel, R.C. (Clarkson Univ., Potsdam, NY (United States). Dept. of Chemistry)

    1993-12-01

    The relative roles of the ion interactions, molecular complex formation, and the local structure of the medium on the formation of nano-sized particles of lead sulfide (PbS) in a nonionic surfactant/water/oil microemulsion have been investigated. Comparison of the reaction carried out under conditions of minimal hydrolysis of the cation (low pH) in two different counterion/acid systems (nitric or perchlorate) indicates that hydrolysis does not play a significant role in the production of PbS in fine particle form. Furthermore, the nature of tile counterion, NO[sub 3][sup [minus

  6. 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.

  7. SPECTRAL-LUMINESCENT CHARACTERISTICS OF FLUOROPHOSPHATE GLASSES ACTIVATED WITH MANGANESE AND CADMIUM SULPHIDE QUANTUM DOTS

    OpenAIRE

    Zhanna O. Lipatova; Vladimir A. Aseev; Elena V. Kolobkova

    2014-01-01

    Research and development of phosphors based on quantum dots (QD) is a perspective problem of photonics. The main advantages of fluorophosphate glass with quantum dots are: high absorption coefficient, solid matrix and a broad band luminescence with high quantum efficiency of QD. Manganese ions have an intense band luminescence in the red region of the spectrum. Thus, the addition of manganese ions in the glass with quantum dots leads to a broadening of the spectrum in the long wav...

  8. A rapid and sensitive assay for determination of doxycycline using thioglycolic acid-capped cadmium telluride quantum dots.

    Science.gov (United States)

    Tashkhourian, Javad; Absalan, Ghodratollah; Jafari, Marzieh; Zare, Saber

    2016-01-05

    A rapid, simple and inexpensive spectrofluorimetric sensor for determination of doxycycline based on its interaction with thioglycolic acid-capped cadmium telluride quantum dots (TGA/CdTe QDs) has been developed. Under the optimum experimental conditions, the sensor exhibited a fast response time of <10s. The results revealed that doxycycline could quench the fluorescence of TGA/CdTe QDs via electron transfer from the QDs to doxycycline through a dynamic quenching mechanism. The sensor permitted determination of doxycycline in a concentration range of 1.9×10(-6)-6.1×10(-5)molL(-1) with a detection limit of 1.1×10(-7)molL(-1). The sensor was applied for determination of doxycycline in honey and human serum samples.

  9. Physicochemical properties of hybrid graphene-lead sulfide quantum dots prepared by supercritical ethanol

    Science.gov (United States)

    Tavakoli, Mohammad Mahdi; Tayyebi, Ahmad; Simchi, Abdolreza; Aashuri, Hossein; Outokesh, Mohmmad; Fan, Zhiyong

    2015-01-01

    Recently, hybrid graphene-quantum dot systems have attracted increasing attention for the next-generation optoelectronic devices such as ultrafast photo-detectors and solar energy harvesting. In this paper, a novel, one-step, reproducible, and solution-processed method is introduced to prepare hybrid graphene-PbS colloids by employing supercritical ethanol. In the hybrid nanocomposite, PbS quantum dots ( 3 nm) are decorated on the reduced graphene oxide (rGO) nanosheets ( 1 nm thickness and less than 1 micron lengths). By employing X-ray photoelectron and Raman and infrared spectroscopy techniques, it is shown that the rGO nanosheets are bonded to PbS nanocrystals through carboxylic bonds. Passivation of {111} planes of PbS quantum dots with rGO nanosheets is demonstrated by employing density function theory. Quenching of the photoluminescence emission of PbS nanocrystals through coupling with graphene sheets is also shown. In order to illustrate that the developed preparation method does not impair the quantum efficiency of the PbS nanocrystals, the photovoltaic efficiency of solar cell device is reported and compared with oleic acid-capped PbS colloidal quantum dot solar cells. By employing the "Hall effect" measurement, it is shown that the carrier mobility is significantly increased (by two orders of magnitudes) in the presence of graphene nanosheets.

  10. Physicochemical properties of hybrid graphene–lead sulfide quantum dots prepared by supercritical ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Tavakoli, Mohammad Mahdi [Sharif University of Technology, Department of Materials Science and Engineering (Iran, Islamic Republic of); Tayyebi, Ahmad [Sharif University of Technology, Department of Energy (Iran, Islamic Republic of); Simchi, Abdolreza, E-mail: simchi@sharif.edu; Aashuri, Hossein [Sharif University of Technology, Department of Materials Science and Engineering (Iran, Islamic Republic of); Outokesh, Mohmmad [Sharif University of Technology, Department of Energy (Iran, Islamic Republic of); Fan, Zhiyong [Hong Kong University of Science and Technology, Department of Electronic and Computer Engineering (Hong Kong)

    2015-01-15

    Recently, hybrid graphene–quantum dot systems have attracted increasing attention for the next-generation optoelectronic devices such as ultrafast photo-detectors and solar energy harvesting. In this paper, a novel, one-step, reproducible, and solution-processed method is introduced to prepare hybrid graphene–PbS colloids by employing supercritical ethanol. In the hybrid nanocomposite, PbS quantum dots (∼3 nm) are decorated on the reduced graphene oxide (rGO) nanosheets (∼1 nm thickness and less than 1 micron lengths). By employing X-ray photoelectron and Raman and infrared spectroscopy techniques, it is shown that the rGO nanosheets are bonded to PbS nanocrystals through carboxylic bonds. Passivation of {111} planes of PbS quantum dots with rGO nanosheets is demonstrated by employing density function theory. Quenching of the photoluminescence emission of PbS nanocrystals through coupling with graphene sheets is also shown. In order to illustrate that the developed preparation method does not impair the quantum efficiency of the PbS nanocrystals, the photovoltaic efficiency of solar cell device is reported and compared with oleic acid-capped PbS colloidal quantum dot solar cells. By employing the “Hall effect” measurement, it is shown that the carrier mobility is significantly increased (by two orders of magnitudes) in the presence of graphene nanosheets.

  11. Highly effective nickel sulfide counter electrode catalyst prepared by optimal hydrothermal treatment for quantum dot-sensitized solar cells

    Science.gov (United States)

    Gopi, Chandu V. V. M.; Srinivasa Rao, S.; Kim, Soo-Kyoung; Punnoose, Dinah; Kim, Hee-Je

    2015-02-01

    Nickel sulfide (NiS) thin film has been deposited on a fluorine-doped tin oxide substrate by a hydrothermal method using 3-mercaptopropionic acid and used as an efficient counter electrode (CE) for polysulfide redox reactions in quantum dot-sensitized solar cells (QDSSCs). NiS has low toxicity and environmental compatibility. In the present study, the size of the NiS nanoparticle increases with the hydrothermal deposition time. The performance of the QDSSCs is examined in detail using polysulfide electrolyte with the NiS CE. A TiO2/CdS/CdSe/ZnS-based QDSSC using the NiS CE shows enhanced photovoltaic performance with a power conversion efficiency (PCE) of 3.03%, which is superior to that of a cell with Pt CE (PCE 2.20%) under one sun illumination (AM 1.5, 100 mW cm-2). The improved photovoltaic performance of the NiS-based QDSSC may be attributed to a low charge transfer resistance (5.08 Ω) for the reduction of polysulfide on the CE, indicating greater electrocatalytic activity of the NiS. Electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel-polarization measurements were used to investigate the electrocatalytic activity of the NiS and Pt CEs.

  12. Genotoxicity of meso-2,3-dimercapto succinic acid-coated silver sulfide quantum dot

    OpenAIRE

    Deniz Özkan Vardar; ibrahim Hacıoğlu; Sevtap Aydin; Funda Yağcı

    2015-01-01

    Nanotecnology products have been used in wide applications in chemistry, electronics, energy generation, and medicine. Despite significant interest in developing quantum dots (QDs) for biomedical applications, many researchers are convinced that QDs will never be used for the treatment of patients because of their potential toxicity. In various in vitro cell culture studies, the cytotoxic properties of some QD have been demonstrated and they have been suggested to be toxic in humans. In this ...

  13. Effect of cadmium sulphide quantum dot processing and post thermal annealing on P3HT/PCBM photovoltaic device

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. Taukeer [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Bhargav, Ranoo [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Kaur, Amarjeet [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Dhawan, S.K., E-mail: skdhawan@mail.nplindia.erne [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Chand, S., E-mail: schand@mail.nplindia.ernet.i [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2010-11-30

    The present study demonstrates the effect on photovoltaic performance of poly(3-hexylthiophene) (P3HT) on doping of cadmium sulphide (CdS) quantum dots (QDs). The P3HT/CdS nanocomposite shows a 10 nm blue shift in the UV-vis absorption relative to the pristine P3HT. The blue shift in the absorption of the P3HT/CdS nanocomposite can be assigned to the quantum confinement effect from the CdS nanoparticles. Significant PL quenching was observed for the nanocomposite films, attributed to additional decaying paths of the excited electrons through the CdS. Solar cell performance of pure P3HT and dispersed with CdS QDs have been studied in the device configuration viz indium tin oxide (ITO)/poly(3,4-ethylendioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS)/P3HT:PCBM/Al and ITO/PEDOT:PSS/ P3HT:CdS:PCBM/Al, respectively. Incorporation of CdS QDs in the P3HT matrix results in the enhancement in the device efficiency ({eta}) of the solar cell from 0.45 to 0.87%. Postproduction thermal annealing at 150 {sup o}C for 30 min improves device performance due to enhancement in the device parameters like FF, V{sub OC} and improvement in contact between active layer and Al.

  14. Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

    KAUST Repository

    Lee, Kyu-Sung

    2011-12-01

    We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

  15. Continuous-Flow Synthesis and Materials Interface Engineering of Lead Sulfide Quantum Dots for Photovoltaic Applications

    KAUST Repository

    El-Ballouli, Ala’a O.

    2016-05-25

    Harnessing the Sun’s energy via the conversion of solar photons to electricity has emerged as a sustainable energy source to fulfill our future demands. In this regard, solution-processable, size-tunable PbS quantum dots (QDs) have been identified as a promising active materials for photovoltaics (PVs). Yet, there are still serious challenges that hinder the full exploitation of QD materials in PVs. This dissertation addresses two main challenges to aid these QDs in fulfilling their tremendous potential in PV applications. First, it is essential to establish a large-scale synthetic technique which maintains control over the reaction parameters to yield QDs with well-defined shape, size, and composition. Rigorous protocols for cost-effective production on a scale are still missing from literature. Particularly, previous reports of record-performance QD-PVs have been based on small-scale, manual, batch syntheses. One way to achieve a controlled large-scale synthesis is by reducing the reaction volume to ensure uniformity. Accordingly, we design a droplet-based continuous-flow synthesis of PbS QDs. Only upon separating the nucleation and growth phases, via a dual-temperature-stage reactor, it was possible to achieve high-quality QDs with high photoluminescence quantum yield (50%) in large-scale. The performance of these QDs in a PV device was comparable to batch-synthesized QDs, thus providing a promise in utilizing automated synthesis of QDs for PV applications. Second, it is crucial to study and control the charge transfer (CT) dynamics at QD interfaces in order to optimize their PV performance. Yet, the CT investigations based on PbS QDs are limited in literature. Here, we investigate the CT and charge separation (CS) at size-tunable PbS QDs and organic acceptor interfaces using a combination of femtosecond broadband transient spectroscopic techniques and steady-state measurements. The results reveal that the energy band alignment, tuned by the quantum

  16. One-Step Synthesis and Photoluminescence Eva-luation of Cadmium-containing Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    Nisha Shukla; Michael M Nigra; Abigail D Ondeck

    2012-01-01

    We have developed a simple one-step process for synthesis of ternary quantum dots (ZnCdSe, MgCdSe) with photoluminescence wavelengths ranging from the red to the blue region of the visible spectrum. The primary aim of this work was to develop a synthesis for the preparation of Cd-containing quantum dots using a Cd precursor with lower toxicity than those used in common syntheses. This synthesis makes use of Cd(acac)2 which is significantly less toxic than precursors such as CdO and CdCl2 . We have studied the effect of solvent boiling point, precursors and reaction time on the photoluminescence properties of the ternary quantum dots. Ternary quantum dots synthesized from Cd(acac)2 in low boiling point solvents have photoluminescence wavelengths in the blue region, while those synthesized in high boiling point solvents have photoluminescence wavelengths in the red region.

  17. Narrow Band Gap Lead Sulfide Hole Transport Layers for Quantum Dot Photovoltaics.

    Science.gov (United States)

    Zhang, Nanlin; Neo, Darren C J; Tazawa, Yujiro; Li, Xiuting; Assender, Hazel E; Compton, Richard G; Watt, Andrew A R

    2016-08-24

    The band structure of colloidal quantum dot (CQD) bilayer heterojunction solar cells is optimized using a combination of ligand modification and QD band gap control. Solar cells with power conversion efficiencies of up to 9.33 ± 0.50% are demonstrated by aligning the absorber and hole transport layers (HTL). Key to achieving high efficiencies is optimizing the relative position of both the valence band and Fermi energy at the CQD bilayer interface. By comparing different band gap CQDs with different ligands, we find that a smaller band gap CQD HTL in combination with a more p-type-inducing CQD ligand is found to enhance hole extraction and hence device performance. We postulate that the efficiency improvements observed are largely due to the synergistic effects of narrower band gap QDs, causing an upshift of valence band position due to 1,2-ethanedithiol (EDT) ligands and a lowering of the Fermi level due to oxidation.

  18. SPECTRAL-LUMINESCENT CHARACTERISTICS OF FLUOROPHOSPHATE GLASSES ACTIVATED WITH MANGANESE AND CADMIUM SULPHIDE QUANTUM DOTS

    Directory of Open Access Journals (Sweden)

    Zhanna O. Lipatova

    2014-11-01

    Full Text Available Research and development of phosphors based on quantum dots (QD is a perspective problem of photonics. The main advantages of fluorophosphate glass with quantum dots are: high absorption coefficient, solid matrix and a broad band luminescence with high quantum efficiency of QD. Manganese ions have an intense band luminescence in the red region of the spectrum. Thus, the addition of manganese ions in the glass with quantum dots leads to a broadening of the spectrum in the long wavelength region. Such emission is closer to natural sunlight and has a high color rendering index. The work objective is the study of the spectral and luminescent properties of fluorophosphate glasses doped with manganese and CdS quantum dots. Fluorophosphate glasses (47NaPO3-30H3PO4-10Ga2O3-5ZnO-xMnS-7,5NaALF6-4,2CdS, where x = 3, 6, 8 mol. % were synthesized. The secondary heat treatment at the temperature of 430 ° C for 90 minutes has led to the growth of quantum dots in glass volume. Absorption spectra have been measured in the visible range (from 300 to 600 nm. Heat treatment has led to a shift of the fundamental absorption edge in the visible region of the spectrum. This change is due to the growth of quantum dots. Maximum intensity of luminescence is shifted to the red region of the spectrum from 620 nm to 660 nm under laser excitation at 410 nm. The maximum shift was observed in the glass with a concentration of 3 mol. % of manganese, the minimum one - in the glass with a concentration of 8 mol. %. Values of manganese ions lifetime from18 ms for a sample with a concentration of MnS 3 mol. % to15 ms for MnS 8 mol % were obtained. The decrease in the lifetime with concentration increasing of manganese ions is due to the concentration quenching of the luminescence. The growth of CdS quantum dots in the heat treatment leads to a decrease of the lifetimes to the values below 9-3 ms (3 and 8 - mol. % MnS, respectively. Obtained findings prove that fluorophosphate

  19. Genotoxicity of meso-2,3-dimercapto succinic acid-coated silver sulfide quantum dot

    Directory of Open Access Journals (Sweden)

    Deniz Özkan Vardar

    2015-06-01

    Full Text Available Nanotecnology products have been used in wide applications in chemistry, electronics, energy generation, and medicine. Despite significant interest in developing quantum dots (QDs for biomedical applications, many researchers are convinced that QDs will never be used for the treatment of patients because of their potential toxicity. In various in vitro cell culture studies, the cytotoxic properties of some QD have been demonstrated and they have been suggested to be toxic in humans. In this study, the cytotoxic properties of Ag2S-(Meso-2,3-Dimercapto Succinic acid nanomaterials in V79 cells (Chinese lung fibroblast cell line were determined by MTT assay. The genotoxic effects of Ag2S-(Meso-2,3-Dimercapto Succinic acid were evaluated by the alkaline single cell gel electrophoresis. The cells were treated with Ag2S-(Meso-2,3-Dimercapto Succinic acid at the concentrations of 5- 2000 µg/ml. No cytotoxic effect of Ag2S-(Meso-2,3-Dimercapto Succinic acid at all concentrations studied was observed. No significant increases in DNA damage were found at the studied concentrations when compared to negative control in V79 cells. In conclusion, further in vitro and in vivo studies are required to determine the safety doses of Ag2S-(Meso-2,3-Dimercapto Succinic acid.

  20. Quantum Confinement in Cadmium Selenide Multilayer Thin Films Using Physical Vapour Deposition Method

    Directory of Open Access Journals (Sweden)

    M. Melvin David Kumar

    2012-06-01

    Full Text Available Nanocrystals of CdSe have been produced in SiOx matrix layer and in ZnSe heterostructure layer by thermal evaporation method. Structural studies were done by X-ray diffractometer. Quantum confinement effect of CdSe nanocrystals was analyzed from optical studies. Bulk CdSe has band-gap energy of 1.756 eV that can be shifted to larger values by reducing the crystal size to dimensions smaller than the Bohr radius of the exciton. Experimentally measured band-gap shifts with respect to the bulk value for quantum dot thin films are compared with the predictions of the effective mass approximation model (i.e., Brus model and Quantum mechanical model. Sizes of the crystallites calculated from both models were coincident with each other.

  1. Synthesis of cadmium chalcogenide based quantum dots for enhanced multiple exciton generation

    OpenAIRE

    2014-01-01

    Quantum dots (QDs) have the potential to produce more than one exciton per incident photon, if the photon energy is greater than twice the band gap energy. This process of multiple exciton generation (MEG) has the potential to lead to a step change in the efficiency of solar panels, by utilising energy commonly wasted as heat in conventional solar cells. A wide range of CdSe/CdTe and CdTe/CdSe quantum dots with and without a CdS shell were synthesised with varying core sizes and shell thickne...

  2. Simultaneous Determination of Adenine and Guanine Using Cadmium Selenide Quantum Dots-Graphene Oxide Nanocomposite Modified Electrode.

    Science.gov (United States)

    Kalaivani, Arumugam; Narayanan, Sangilimuthu Sriman

    2015-06-01

    A novel electrochemical sensor was fabricated by immobilizing Cadmium Selenide Quantum Dots (CdSe QDs)-Graphene Oxide (GO) nanocomposite on a paraffin wax impregnated graphite electrode (PIGE) and was used for the simultaneous determination of adenine and guanine. The CdSe QDs-GO nanocomposite was prepared by ultrasonication and was characterized with spectroscopic and microscopic techniques. The nanocomposite modified electrode was characterized by cyclic voltammetry (CV). The modified electrode showed excellent electrocatalytic activity towards the oxidative determination of adenine and guanine with a good peak separation of 0.31 V. This may be due to the high surface area and fast electron transfer kinetics of the nanocomposite. The modified electrode exhibited wide linear ranges from 0.167 μM to 245 μM for Guanine and 0.083 μM to 291 μM for Adenine with detection limits of 0.055 μM Guanine and 0.028 μM of Adenine (S/N = 3) respectively. Further, the modified electrode was used for the quantitative determination of adenine and guanine in herring sperm DNA with satisfactory results. The modified electrode showed acceptable selectivity, reproducibility and stability under optimal conditions.

  3. 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.

  4. Improved Sensitization of Zinc Oxide Nanorods by Cadmium Telluride Quantum Dots through Charge Induced Hydrophilic Surface Generation

    Directory of Open Access Journals (Sweden)

    Karthik Laxman

    2014-01-01

    Full Text Available This paper reports on UV-mediated enhancement in the sensitization of semiconductor quantum dots (QDs on zinc oxide (ZnO nanorods, improving the charge transfer efficiency across the QD-ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect-free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD-ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.

  5. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P., E-mail: bhanuprs@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Mumbai- 400076 (India)

    2015-05-15

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  6. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    Science.gov (United States)

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P.

    2015-05-01

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  7. Optical and photovoltaic properties of zinc sulfide quantum dots fabricated by spin-assisted successive ion layer adsorption and reaction technique

    Science.gov (United States)

    Mehrabian, Masood; Mirabbaszadeh, Kavoos; Afarideh, Hossein; Kim, Yoon Sang

    2014-01-01

    Zinc sulfide (ZnS) quantum dots were prepared by successive ion layer adsorption and reaction (SILAR) technique based on spin coating (spin-SILAR). The effect of the number of SILAR cycle (n) on optical and photovoltaic properties was studied. An optimized ZnS quantum dot sensitized solar cell demonstrated maximum power conversion efficiency of 3.58% with a short-circuit current of 10.53 mA/cm2 and an open-circuit voltage of 0.58 V under one sun illumination (AM1.5). The results showed that a ZnS QD layer with n=10 (thickness ˜80 nm) can be used as a highly efficient sensitizer for solar cells. The ZnS QD layer acts as a light absorber and a recombination blocking layer in the ITO/ZnO film/ZnS QD/P3HT/PCBM/Ag structure.

  8. An ultrasensitive method for the determination of melamine using cadmium telluride quantum dots as fluorescence probes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiafei; Li, Jin; Kuang, Huiyan; Feng, Lei; Yi, Shoujun; Xia, Xiaodong; Huang, Haowen [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); Chen, Yong; Tang, Chunran [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Zeng, Yunlong, E-mail: yunlongzeng1955@126.com [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-11-13

    Graphical abstract: Melamine takes place of the TGA on the surface of TGA-CdTe QDs with negative charge to form melamine coated QDs changing the surface charge of the QDs, resulting the fluorescence quenched as the QDs aggregation occurred by electrostatic attraction of the two opposite charged nanocrystals. -- Highlights: •An ultrasensitive and selective method for the determination of melamine was developed at pH 11.0. •The selectivity of the method was improved. •The sensitivity of the method enhanced obviously as the CdTe QDs have higher QYs at pH 11. •The sensitivity and linear range for the analysis are size dependent using QDs PL probes. •Melamine takes the place of TGA resulting fluorescence quenched of QDs. -- Abstract: An ultrasensitive and simple method for the determination of melamine was developed based on the fluorescence quenching of thioglycolic acid (TGA) capped CdTe quantum dots (QDs) at pH 11.0. In strong alkaline aqueous solution, the selectivity of the method has been greatly improved due to most heavy metal ions show no interference as they are in the precipitation form or in their anion form. Furthermore, CdTe quantum dots have higher quantum yields at higher pH. The method has a wider concentration range and lower detection limit. The influence factors on the determination of melamine were investigated and the optimum conditions were determined. Under optimum conditions, the fluorescence intensity change of TGA coated CdTe quantum dots was linearly proportional to melamine over a concentration range from 1.0 × 10{sup −11} to 1.0 × 10{sup −5} mol L{sup −1} with a correlation coefficient of 0.9943 and a detection limit of 5 × 10{sup −12} mol L{sup −1}. The mechanism of fluorescence quenching of the QDs has been proposed based on the infrared spectroscopy information and electrophoresis experiments in presence of melamine under alkaline condition. The proposed method was employed to detect trace melamine in milk powder

  9. Toxicokinetics and tissue distribution of cadmium-based Quantum Dots in the marine mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Rocha, Thiago Lopes; Gomes, Tânia; Pinheiro, José Paulo; Sousa, Vânia Serrão; Nunes, Luís Miguel; Teixeira, Margarida Ribau; Bebianno, Maria João

    2015-09-01

    Environmental health hazards of Quantum Dots (QDs) are of emergent concern, but limited data is available about their toxicokinetics (TK) and tissue distribution in marine bivalves. This study investigated the QDs behavior in seawater, their TK and tissue distribution in Mytilus galloprovincialis, in comparison with soluble Cd. Mussels were exposed to CdTe QDs and soluble Cd for 21 days at 10 μgCd L(-1) followed by a 50 days depuration. TK of QDs in mussels is related to the homo-aggregate uptake, surface charge, aggregation and precipitation as key factors. There were tissue- and time-dependent differences in the TK of both Cd forms, and soluble Cd is the most bioavailable form. Digestive gland is a preferential site for QDs storage and both Cd forms are not eliminated by mussels (t1/2>50 days). Results indicate that the TK model of CdTe QDs in marine mussels is distinct from their soluble counterparts.

  10. Tissue specific responses to cadmium-based quantum dots in the marine mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Rocha, Thiago Lopes; Gomes, Tânia; Mestre, Nélia C; Cardoso, Cátia; Bebianno, Maria João

    2015-12-01

    In recent years, Cd-based quantum dots (QDs) have generated interest from the life sciences community due to their potential applications in nanomedicine, biology and electronics. However, these engineered nanomaterials can be released into the marine environment, where their environmental health hazards remain unclear. This study investigated the tissue-specific responses related to alterations in the antioxidant defense system induced by CdTe QDs, in comparison with its dissolved counterpart, using the marine mussel Mytilus galloprovincialis. Mussels were exposed to CdTe QDs and dissolved Cd for 14 days at 10 μgCd L(-1) and biomarkers of oxidative stress [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (total, Se-independent and Se-dependent GPx) and glutathione-S-transferase (GST) activities] were analyzed along with Cd accumulation in the gills and digestive gland of mussels. Results show that both Cd forms changed mussels' antioxidant responses with distinct modes of action (MoA). There were tissue- and time-dependent differences in the biochemical responses to each Cd form, wherein QDs are more pro-oxidant when compared to dissolved Cd. The gills are the main tissue affected by QDs, with effects related to the increase of SOD, GST and GPx activities, while those of dissolved Cd was associated to the increase of CAT activity, Cd accumulation and exposure time. Digestive gland is a main tissue for accumulation of both Cd forms, but changes in antioxidant enzyme activities are smaller than in gills. A multivariate analysis revealed that the antioxidant patterns are tissue dependent, indicating nano-specific effects possibly associated to oxidative stress and changes in redox homeostasis.

  11. Tissue specific responses to cadmium-based quantum dots in the marine mussel Mytilus galloprovincialis

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Thiago Lopes [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Gomes, Tânia [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo (Norway); Mestre, Nélia C.; Cardoso, Cátia [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Bebianno, Maria João, E-mail: mbebian@ualg.pt [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2015-12-15

    Highlights: • Mussel gills are the main target for oxidative stress induced by Cd-based QDs. • Antioxidants responses induced by Cd-based QDs and dissolved Cd are mediated by different mechanisms. • CdTe QDs are more pro-oxidant Cd form when compared to dissolved Cd. • Differential tissue response indicated nano-specific effects. - Abstract: In recent years, Cd-based quantum dots (QDs) have generated interest from the life sciences community due to their potential applications in nanomedicine, biology and electronics. However, these engineered nanomaterials can be released into the marine environment, where their environmental health hazards remain unclear. This study investigated the tissue-specific responses related to alterations in the antioxidant defense system induced by CdTe QDs, in comparison with its dissolved counterpart, using the marine mussel Mytilus galloprovincialis. Mussels were exposed to CdTe QDs and dissolved Cd for 14 days at 10 μgCd L{sup −1} and biomarkers of oxidative stress [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (total, Se-independent and Se-dependent GPx) and glutathione-S-transferase (GST) activities] were analyzed along with Cd accumulation in the gills and digestive gland of mussels. Results show that both Cd forms changed mussels’ antioxidant responses with distinct modes of action (MoA). There were tissue- and time-dependent differences in the biochemical responses to each Cd form, wherein QDs are more pro-oxidant when compared to dissolved Cd. The gills are the main tissue affected by QDs, with effects related to the increase of SOD, GST and GPx activities, while those of dissolved Cd was associated to the increase of CAT activity, Cd accumulation and exposure time. Digestive gland is a main tissue for accumulation of both Cd forms, but changes in antioxidant enzyme activities are smaller than in gills. A multivariate analysis revealed that the antioxidant patterns are tissue dependent

  12. Size and temperature dependence of the photoluminescence properties of NIR emitting ternary alloyed mercury cadmium telluride quantum dots

    Science.gov (United States)

    Jagtap, Amardeep M.; Chatterjee, Abhijit; Banerjee, Arup; Babu Pendyala, Naresh; Koteswara Rao, K. S. R.

    2016-04-01

    Exciton-phonon coupling and nonradiative relaxation processes have been investigated in near-infrared (NIR) emitting ternary alloyed mercury cadmium telluride (CdHgTe) quantum dots. Organically capped CdHgTe nanocrystals of sizes varying from 2.5-4.2 nm have been synthesized where emission is in the NIR region of 650-855 nm. Temperature-dependent (15-300 K) photoluminescence (PL) and the decay dynamics of PL at 300 K have been studied to understand the photophysical properties. The PL decay kinetics shows the transition from triexponential to biexponential on increasing the size of the quantom dots (QDs), informing the change in the distribution of the emitting states. The energy gap is found to be following the Varshni relation with a temperature coefficient of 2.1-2.8  ×  10-4 eV K-1. The strength of the electron-phonon coupling, which is reflected in the Huang and Rhys factor S, is found in the range of 1.17-1.68 for QDs with a size of 2.5-4.2 nm. The integrated PL intensity is nearly constant until 50 K, and slowly decreases up to 140 K, beyond which it decreases at a faster rate. The mechanism for PL quenching with temperature is attributed to the presence of nonradiative relaxation channels, where the excited carriers are thermally stimulated to the surface defect/trap states. At temperatures of different region (<140 K and 140-300 K), traps of low (13-25 meV) and high (65-140 meV) activation energies seem to be controlling the quenching of the PL emission. The broadening of emission linewidth is found to due to exciton-acoustic phonon scattering and exciton-longitudinal optical (LO) phonon coupling. The exciton-acoustic phonon scattering coefficient is found to be enhanced up to 55 μeV K-1 due to a stronger confinement effect. These findings give insight into understanding the photophysical properties of CdHgTe QDs and pave the way for their possible applications in the fields of NIR photodetectors and other optoelectronic devices.

  13. PEG-phospholipid-encapsulated bismuth sulfide and CdSe/ZnS quantum dot core–shell nanoparticle and its computed tomography/fluorescence performance

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jun; Yang, Xiao-Quan; Qin, Meng-Yao; Zhang, Xiao-Shuai; Xuan, Yang; Zhao, Yuan-Di, E-mail: zydi@mail.hust.edu.cn [Huazhong University of Science and Technology, Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology (China)

    2015-11-15

    In this paper, polyethylene glycol-phospholipid structure is used to synthesize hybrid cluster of 40–50 nm diameter that contains hydrophobic bismuth sulfide nanoparticles and CdSe/ZnS quantum dots. The composite probe’s toxicity, CT imaging, and fluorescence imaging performance are also studied. Experimental results show that the nanocomposite hybrid cluster has obvious CT contrast enhancement and fluorescence imaging capability in vitro even after cellular uptake. It gives a CT number of 700 (Hounsfield units) at 15 mg/mL, higher than that of the current iobitridol CT contrast agent. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide experiment reveals that it has low cytotoxicity at concentration up to of 3.14 mg/mL of Bi, indicating the composite probe has potential ability for CT and fluorescence bimodal imaging.

  14. Tunable optical properties of colloidal quantum dots in electrolytic environments.

    Science.gov (United States)

    Ramadurai, D; Kohanpour, B; Alexson, D; Shi, P; Sethuraman, A; Li, Y; Saini, V; Dutta, M; Stroscio, M A

    2004-12-01

    The absorption spectra of colloidal cadmium sulfide quantum dots in electrolytic solutions are found to manifest a shift in the absorption threshold as the concentration of the electrolyte is varied. These results are consistent with a shift in the absorption threshold that would be caused by electrolytic screening of the field caused by the intrinsic spontaneous polarisation of these würtzite structured quantum dots. These electrolyte-dependent absorption properties provide a potential means of gaining insights on the variable extracellular and intracellular electrolytic concentrations that are present in biological systems.

  15. Synthesis of Bi2S3 quantum dots for sensitized solar cells by reverse SILAR

    Science.gov (United States)

    Singh, Navjot; Sharma, J.; Tripathi, S. K.

    2016-05-01

    Quantum Dot Sensitized Solar cells (QDSSC) have great potential to replace silicon-based solar cells. Quantum dots of various materials and sizes could be used to convert most of the visible light into the electrical current. This paper put emphasis on the synthesis of Bismuth Sulphide quantum dots and selectivity of the anionic precursor by Successive Ionic Layer Adsorption Reaction (SILAR). Bismuth Sulfide (Bi2S3) (group V - Vi semiconductor) is strong contestant for cadmium free solar cells due to its optimum band gap for light harvesting. Optical, structural and electrical measurements are reported and discussed. Problem regarding the choice of precursor for anion extraction is discussed. Band gap of the synthesized quantum dots is 1.2 eV which does not match with the required energy band gap of bismuth sulfide that is 1.7eV.

  16. Efficient charge transfer and field-induced tunneling transport in hybrid composite device of organic semiconductor and cadmium telluride quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Varade, Vaibhav, E-mail: vaibhav.tvarade@gmail.com; Jagtap, Amardeep M.; Koteswara Rao, K. S. R.; Ramesh, K. P.; Menon, R. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Anjaneyulu, P. [Department of Physics, Gitam University, Hyderabad 502329 (India)

    2015-06-07

    Temperature and photo-dependent current–voltage characteristics are investigated in thin film devices of a hybrid-composite comprising of organic semiconductor poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and cadmium telluride quantum dots (CdTe QDs). A detailed study of the charge injection mechanism in ITO/PEDOT:PSS-CdTe QDs/Al device exhibits a transition from direct tunneling to Fowler–Nordheim tunneling with increasing electric field due to formation of high barrier at the QD interface. In addition, the hybrid-composite exhibits a huge photoluminescence quenching compared to aboriginal CdTe QDs and high increment in photoconductivity (∼ 400%), which is attributed to the charge transfer phenomena. The effective barrier height (Φ{sub B} ≈ 0.68 eV) is estimated from the transition voltage and the possible origin of its variation with temperature and photo-illumination is discussed.

  17. Highly sensitive photodetectors based on hybrid 2D-0D SnS{sub 2}-copper indium sulfide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yun; Zhan, Xueying; Xu, Kai; Yin, Lei; Cheng, Zhongzhou; Jiang, Chao; Wang, Zhenxing, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn; He, Jun, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China)

    2016-01-04

    Both high speed and efficiency of photoelectric conversion are essential for photodetectors. As an emerging layered metal dichalcogenide (LMD), tin disulfide owns intrinsic faster photodetection ability than most other LMDs but poor light absorption and low photoelectric conversion efficiency. We develop an efficient method to enhance its performance by constructing a SnS{sub 2}-copper indium sulfide hybrid structure. As a result, the responsivity reaches 630 A/W, six times stronger than pristine SnS{sub 2} and much higher than most other LMDs photodetectors. Additionally, the photocurrents are enhanced by more than 1 order of magnitude. Our work may open up a pathway to improve the performance of photodetectors based on LMDs.

  18. Synthesis and Resonance Energy Transfer in Conjugates of Luminescent Cadmium Selenide Quantum Dots and Chlorin e6 Molecules

    Science.gov (United States)

    Fedosyuk, A. A.; Artemyev, M. V.

    2013-05-01

    We synthesized a new type of conjugates of highly luminescent water soluble CdSe/ZnS colloidal quantum dots covalently bound to Chlorin e6 dye molecules. We observed a resonance energy transfer from quantum dots emitting at 660 nm to Chlorine e6 molecules in our conjugates which can be utilized for phototherapy. Contrary to that quantum dots emitting at 588 nm show non-resonance quenching of excitonic luminescence without the energy transfer to dye molecules.

  19. Lead antimony sulfide (Pb5Sb8S17) solid-state quantum dot-sensitized solar cells with an efficiency of over 4%

    Science.gov (United States)

    Chang, Yi-Cheng; Suriyawong, Nipapon; Aragaw, Belete Asefa; Shi, Jen-Bin; Chen, Peter; Lee, Ming-Way

    2016-04-01

    Lead antimony sulfides are rare in nature and relatively unexplored ternary semiconductors. This work investigates the photovoltaic performance of Pb-Sb-S quantum dot-sensitized solar cells (QDSCs). Pb5Sb8S17 nanoparticles are grown on mesoporous TiO2 electrodes using the successive ionic layer adsorption reaction process. The synthesized Pb5Sb8S17 nanoparticles exhibit two attractive features for a good solar absorber material: a high optical absorption coefficient and a near optimal energy gap. Solid-state QDSCs are fabricated from the synthesized Pb5Sb8S17 nanoparticles using Spiro-OMeTAD as the hole-transporting material. The best cell yields a short-circuit current density Jsc of 11.92 mA cm-2, an open-circuit voltage Voc of 0.48 V, a fill factor FF of 30.7% and a power conversion efficiency (PCE) of 1.76% under 1sun. The external quantum efficiency (EQE) spectrum covers a spectral range of 350-800 nm with a maximal EQE = 65% at λ = 450 nm. At the reduced light intensity of 10% sun, the PCE increases to 4.14% with Jsc = 2.0 mA cm-2 (which could be normalized to 20 mA cm-2 under 1 sun). This PCE is 65% higher than the best previous result. The respectable PCE and Jsc indicate that Pb5Sb8S17 could be a potential candidate for a solar absorber material.

  20. Indium sulfide buffer/CIGSSe interface engineering: Improved cell performance by the addition of zinc sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Allsop, N.A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)]. E-mail: allsop@hmi.de; Camus, C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Haensel, A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Gledhill, S.E. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lauermann, I. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lux-Steiner, M.C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Fischer, Ch.-H. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)

    2007-05-31

    Indium sulfide buffer layers deposited by the spray-ion layer gas reaction (Spray-ILGAR) technique are a viable alternative to the traditional cadmium sulfide buffer layer in thin film solar cells. In the present work we report on the results of manipulating the absorber/buffer interface between the chalcopyrite Cu(In,Ga)(S,Se){sub 2} absorber (CIGSSe) and the indium sulfide buffer. It is shown that the deposition of a small amount of zinc sulfide at the absorber/buffer interface can be used to increase the open circuit voltage. A small but significant increase of 20 mV (up to 580 mV), as compared to the pure indium sulfide buffered cells is possible leading to an increase in the overall efficiency.

  1. In vivo cancer targeting and fluorescence-CT dual-mode imaging with nanoprobes based on silver sulfide quantum dots and iodinated oil.

    Science.gov (United States)

    Qin, Meng-Yao; Yang, Xiao-Quan; Wang, Kan; Zhang, Xiao-Shuai; Song, Ji-Tao; Yao, Ming-Hao; Yan, Dong-Mei; Liu, Bo; Zhao, Yuan-Di

    2015-12-14

    In this article, a fluorescence-CT dual-mode nanoprobe is successfully synthesized by making use of distearoylphosphatidylethanolamine-poly(ethylene glycol)-folate (DSPE-PEG2000-FA) and other amphiphilic molecules to coat silver sulfide (Ag2S) quantum dots (QDs) and iodinated oil simultaneously. In vitro experiments show that the fluorescence wavelength of the nanoprobe is 1170 nm in the near infrared-II region. Its size is 139.6 nm, it has good dispersibility, and it has low cellular toxicity at concentrations up to 25 μg mL(-1) Ag. In vivo experiments revealed that the probe has a rather long circulation time (blood half-life of 5.7 hours), and the tissue histopathological tests show that it is not obviously harmful to major organs' normal function. Biochemical analysis (glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels) and blood analysis (white blood cell, red blood cell, hemoglobin and blood platelet counts) reveal that it has little influence on blood within 15 days of administration. When injected into HeLa xenograft nude mice by the tail vein, the probe elicited intensely enhanced fluorescence and X-ray computed tomography (CT) signals in the tumors after 24 hours, and the structure, size and position of tumor tissue were shown clearly. In a word, the probe has good tumor targeting capabilities, and it has significant value in fluorescence-CT dual-mode imaging in vivo.

  2. Cadmium-free aqueous synthesis of ZnSe and ZnSe@ZnS core–shell quantum dots and their differential bioanalyte sensing potential

    Science.gov (United States)

    Mir, Irshad Ahmad; Rawat, Kamla; Bohidar, H. B.

    2016-10-01

    Herein we report a facile and cadmium-free approach to prepare water-soluble fluorescent ZnSe@ZnS core–shell quantum dots (QDs), using thioglycolic acid (TGA) ligand as a stabilizer and thiourea as a sulfur source. The optical properties and morphology of the obtained core–shell QDs were characterized by UV–vis and fluorescence spectroscopy, transmission electron microscopy (TEM), energy-dispersive x-ray analysis (EDX), x-ray diffraction (XRD), electrophoresis and dynamic light scattering (DLS) techniques. TEM analysis, and electrophoresis data showed that ZnSe core had an average size of 3.60 ± 0.12 nm and zeta potential of ‑38 mV; and for ZnSe@ZnS QDs, the mean size was 4.80 ± 0.20 nm and zeta potential was ‑45 mV. Compared to the core ZnSe QDs, the quantum yield of these core–shell structures was higher (13% versus 32%). These were interacted with five common bioanalytes such as, ascorbic acid, citric acid, oxalic acid, glucose and cholesterol which revealed fluorescence quenching due to concentration dependent binding of analytes to the core only, and core–shell QDs. The binding pattern followed the sequence: cholesterol shell QDs. Thus, enhanced binding was noticed for the analyte citric acid which may facilitate development of a fluorescence-based sensor based on the ZnSe core-only quantum dot platform. Further, the hydrophilic core–shell structure may find use in cell imaging applications.

  3. Distance-dependent energy transfer between CdSe/CdS quantum dots and a two-dimensional semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Goodfellow, Kenneth M.; Vamivakas, A. Nick, E-mail: nick.vamivakas@rochester.edu [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Chakraborty, Chitraleema [Materials Science, University of Rochester, Rochester, New York 14627 (United States); Sowers, Kelly [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States); Waduge, Pradeep; Wanunu, Meni [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Krauss, Todd [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States); Driscoll, Kristina [Department of Physics, Rochester Institute of Technology, Rochester, New York 14627 (United States)

    2016-01-11

    Atomically thin semiconductors, such as the transition metal dichalcogenides, show great potential for nanoscale photodetection, energy harvesting, and nanophotonics. Here, we investigate the efficiency of energy transfer between colloidal quantum dots with a cadmium selenide core and cadmium sulfide shell and monolayer molybdenum diselenide (MoSe{sub 2}). We show that MoSe{sub 2} effectively quenches the fluorescence of quantum dots when the two materials are in contact. We then separate the MoSe{sub 2} and quantum dots by inserting variable thickness hexagonal boron nitride (h-BN) spacers and show that the efficiency at which the MoSe{sub 2} quenches fluorescence decreases as the h-BN thickness is increased. For distances d, this trend can be modeled by a 1/d{sup 4} decay, in agreement with theory and recent studies involving graphene.

  4. Doped zinc sulfide quantum dots based phosphorescence turn-off/on probe for detecting histidine in biological fluid

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Wei [School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); School of Basic Medical Science, Shanxi Medical University, Taiyuan 030001 (China); Wang, Fang [School of Basic Medical Science, Shanxi Medical University, Taiyuan 030001 (China); Wei, Yanli; Wang, Li; Liu, Qiaoling; Dong, Wenjuan [School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Shuang, Shaomin, E-mail: smshuang@sxu.edu.cn [School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Choi, Martin M.F., E-mail: mmfchoi@gmail.com [Partner State Key Laboratory of Environmental and Biological Analysis, and Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, Hong Kong SAR (China)

    2015-01-26

    Highlights: • A turn-on phosphorescence quantum dots probe for histidine is fabricated. • High sensitivity, good selectivity and low interference are achieved. • Histidine in urine samples can be easily detected by the phosphorescence probe. - Abstract: We report a turn-on phosphorescence probe for detection of histidine based on Co{sup 2+}-adsorbed N-acetyl-L-cysteine (NAC) capped Mn: ZnS quantum dots (QDs) which is directly synthesized by the hydrothermal method. The phosphorescence of NAC-Mn: ZnS QDs is effectively quenched by Co{sup 2+} attributing to the adsorption of Co{sup 2+} onto the surface of QDs with a concomitant in suppressing the recombination process of hole and electron of QDs. The phosphorescence of Co{sup 2+}-adsorbed NAC-Mn: ZnS QDs can be recovered by binding of Co{sup 2+} with histidine. The quenching and regeneration of the phosphorescence of NAC-Mn: ZnS QDs have been studied in detail. The as-prepared QDs-based probe is applied to determine histidine with a linear range of 1.25–30 μM and a detection limit of 0.74 μM. The relative standard deviation for eleven repeat detections of 20 μM histidine is 0.65%. Co{sup 2+}-adsorbed NAC-Mn: ZnS QDs show high sensitivity and good selectivity to histidine over other amino acids, metal ions and co-existing substances. The proposed QDs probe has been successfully applied to determination of histidine in human urine samples with good recoveries of 98.5–103%.

  5. In vivo cancer targeting and fluorescence-CT dual-mode imaging with nanoprobes based on silver sulfide quantum dots and iodinated oil

    Science.gov (United States)

    Qin, Meng-Yao; Yang, Xiao-Quan; Wang, Kan; Zhang, Xiao-Shuai; Song, Ji-Tao; Yao, Ming-Hao; Yan, Dong-Mei; Liu, Bo; Zhao, Yuan-Di

    2015-11-01

    In this article, a fluorescence-CT dual-mode nanoprobe is successfully synthesized by making use of distearoylphosphatidylethanolamine-poly(ethylene glycol)-folate (DSPE-PEG2000-FA) and other amphiphilic molecules to coat silver sulfide (Ag2S) quantum dots (QDs) and iodinated oil simultaneously. In vitro experiments show that the fluorescence wavelength of the nanoprobe is 1170 nm in the near infrared-II region. Its size is 139.6 nm, it has good dispersibility, and it has low cellular toxicity at concentrations up to 25 μg mL-1 Ag. In vivo experiments revealed that the probe has a rather long circulation time (blood half-life of 5.7 hours), and the tissue histopathological tests show that it is not obviously harmful to major organs' normal function. Biochemical analysis (glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels) and blood analysis (white blood cell, red blood cell, hemoglobin and blood platelet counts) reveal that it has little influence on blood within 15 days of administration. When injected into HeLa xenograft nude mice by the tail vein, the probe elicited intensely enhanced fluorescence and X-ray computed tomography (CT) signals in the tumors after 24 hours, and the structure, size and position of tumor tissue were shown clearly. In a word, the probe has good tumor targeting capabilities, and it has significant value in fluorescence-CT dual-mode imaging in vivo.In this article, a fluorescence-CT dual-mode nanoprobe is successfully synthesized by making use of distearoylphosphatidylethanolamine-poly(ethylene glycol)-folate (DSPE-PEG2000-FA) and other amphiphilic molecules to coat silver sulfide (Ag2S) quantum dots (QDs) and iodinated oil simultaneously. In vitro experiments show that the fluorescence wavelength of the nanoprobe is 1170 nm in the near infrared-II region. Its size is 139.6 nm, it has good dispersibility, and it has low cellular toxicity at concentrations up to 25 μg mL-1 Ag. In vivo experiments revealed that the

  6. Effects of long-term exposure of gelatinated and non-gelatinated cadmium telluride quantum dots on differentiated PC12 cells

    Directory of Open Access Journals (Sweden)

    Prasad Babu R

    2012-01-01

    Full Text Available Abstract Background The inherent toxicity of unmodified Quantum Dots (QDs is a major hindrance to their use in biological applications. To make them more potent as neuroprosthetic and neurotherapeutic agents, thioglycolic acid (TGA capped CdTe QDs, were coated with a gelatine layer and investigated in this study with differentiated pheochromocytoma 12 (PC12 cells. The QD - cell interactions were investigated after incubation periods of up to 17 days by MTT and APOTOX-Glo Triplex assays along with using confocal microscopy. Results Long term exposure (up to 17 days to gelatinated TGA-capped CdTe QDs of PC12 cells in the course of differentiation and after neurites were grown resulted in dramatically reduced cytotoxicity compared to non-gelatinated TGA-capped CdTe QDs. Conclusion The toxicity mechanism of QDs was identified as caspase-mediated apoptosis as a result of cadmium leaking from the core of QDs. It was therefore concluded that the gelatine capping on the surface of QDs acts as a barrier towards the leaking of toxic ions from the core QDs in the long term (up to 17 days.

  7. Effects of Long-term exposure of Gelatinated and Non-gelatinated Cadmium Telluride Quantum Dots on Differentiated PC12 cells

    LENUS (Irish Health Repository)

    Prasad, Babu R

    2012-01-20

    Abstract Background The inherent toxicity of unmodified Quantum Dots (QDs) is a major hindrance to their use in biological applications. To make them more potent as neuroprosthetic and neurotherapeutic agents, thioglycolic acid (TGA) capped CdTe QDs, were coated with a gelatine layer and investigated in this study with differentiated pheochromocytoma 12 (PC12) cells. The QD - cell interactions were investigated after incubation periods of up to 17 days by MTT and APOTOX-Glo Triplex assays along with using confocal microscopy. Results Long term exposure (up to 17 days) to gelatinated TGA-capped CdTe QDs of PC12 cells in the course of differentiation and after neurites were grown resulted in dramatically reduced cytotoxicity compared to non-gelatinated TGA-capped CdTe QDs. Conclusion The toxicity mechanism of QDs was identified as caspase-mediated apoptosis as a result of cadmium leaking from the core of QDs. It was therefore concluded that the gelatine capping on the surface of QDs acts as a barrier towards the leaking of toxic ions from the core QDs in the long term (up to 17 days).

  8. 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.

  9. 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.

  10. Doped zinc sulfide quantum dots based phosphorescence turn-off/on probe for detecting histidine in biological fluid.

    Science.gov (United States)

    Bian, Wei; Wang, Fang; Wei, Yanli; Wang, Li; Liu, Qiaoling; Dong, Wenjuan; Shuang, Shaomin; Choi, Martin M F

    2015-01-26

    We report a turn-on phosphorescence probe for detection of histidine based on Co(2+)-adsorbed N-acetyl-L-cysteine (NAC) capped Mn: ZnS quantum dots (QDs) which is directly synthesized by the hydrothermal method. The phosphorescence of NAC-Mn: ZnS QDs is effectively quenched by Co(2+) attributing to the adsorption of Co(2+) onto the surface of QDs with a concomitant in suppressing the recombination process of hole and electron of QDs. The phosphorescence of Co(2+)-adsorbed NAC-Mn: ZnS QDs can be recovered by binding of Co(2+) with histidine. The quenching and regeneration of the phosphorescence of NAC-Mn: ZnS QDs have been studied in detail. The as-prepared QDs-based probe is applied to determine histidine with a linear range of 1.25-30 μM and a detection limit of 0.74 μM. The relative standard deviation for eleven repeat detections of 20 μM histidine is 0.65%. Co(2+)-adsorbed NAC-Mn: ZnS QDs show high sensitivity and good selectivity to histidine over other amino acids, metal ions and co-existing substances. The proposed QDs probe has been successfully applied to determination of histidine in human urine samples with good recoveries of 98.5-103%.

  11. Development of cadmium-free quantum dot for intracellular labelling through electroporation or lipid-calcium-phosphate

    Science.gov (United States)

    Liu, Ying-Feng; Hung, Wei-Ling; Hou, Tzh-Yin; Huang, Hsiu-Ying; Lin, Cheng-An J.

    2016-04-01

    Traditional fluorescent labelling techniques has severe photo-bleaching problem such as organic dyes and fluorescent protein. Quantum dots made up of traditional semiconductor (CdSe/ZnS) material has sort of biological toxicity. This research has developed novel Cd-free quantum dots divided into semiconductor (Indium phosphide, InP) and noble metal (Gold). Former has lower toxicity compared to traditional quantum dots. Latter consisting of gold (III) chloride (AuCl3) and toluene utilizes sonochemical preparation and different stimulus to regulate fluorescent wavelength. Amphoteric macromolecule surface technology and ligand Exchange in self-Assembled are involved to develop hydrophilic nanomaterials which can regulate the number of grafts per molecule of surface functional groups. Calcium phosphate (CaP) nanoparticle (NP) with an asymmetric lipid bilayer coating technology developed for intracellular delivery and labelling has synthesized Cd-free quantum dots possessing high brightness and multi-fluorescence successfully. Then, polymer coating and ligand exchange transfer to water-soluble materials to produce liposome nanomaterials as fluorescent probes and enhancing medical applications of nanotechnology.

  12. Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots

    Science.gov (United States)

    Haugen, Neale O.

    The use of single wall carbon nanotubes (SW-CNTs) in solar photovoltaic (PV) devices is a relatively new, but quickly growing field. SW-CNTs have found application as transparent front contacts, and high work function back contacts in thin film solar PV. For the utility of SW-CNTs to be fully realized, however, controllable and stable doping as well as long term protection from doping must be achieved. Spectroscopic techniques facilitate detailed investigations of the intrinsic and variable properties of semiconductor materials without the issues of contact deposition and the possibility of sample contamination. Detailed spectroscopic analysis of the doping induced changes in the optical properties of SW-CNTs has revealed normally hidden excited state transitions in large diameter single walled carbon nanotubes for the first time. Spectroscopic monitoring of the degree of doping in SW-CNTs made possible studies of the dopant complex desorption and readsorption energies and kinetics. The long term protection from doping of SW-CNTs exposed to ambient laboratory conditions was achieved as a result of the more detailed understanding of the doping processes and mechanisms yielded by these spectroscopic studies. The application of SW-CNTs to other roles in solar PV devices was another goal of this research. Efficient collection of photogenerated charge carriers in semiconductor quantum dot (QD) based solar photovoltaic devices has been limited primarily by the poor transport properties and high density of recombination sites in the QD films. Coupling semiconductor QDs to nanomaterials with better transport properties is one potential solution to the poor transport within the QD films. This portion of the work investigated the possibility of charge transfer occurring in nano-heterostructures (NHSs) of PbS QDs and SW-CNTs produced through spontaneous self-assembly in solution. Electronic coupling in the form of charge transfer from the QDs to the SW-CNTs is unambiguously

  13. The Determination of Hydrogen Sulfide in Stack Gases, Iodometric Titration After Sulfite Removal.

    Science.gov (United States)

    Robles, E. G.

    The determination of hydrogen sulfide in effluents from coal-fired furnaces and incinerators is complicated by the presence of sulfur oxides (which form acids). Organic compounds also may interfere with or prevent the formation of the cadmium sulfide precipitate or give false positive results because of reaction with iodine. The report presents a…

  14. Eco-friendly intracellular biosynthesis of CdS quantum dots without changing Escherichia coli's antibiotic resistance.

    Science.gov (United States)

    Yan, Zheng-Yu; Du, Qing-Qing; Qian, Jing; Wan, Dong-Yu; Wu, Sheng-Mei

    2017-01-01

    In the paper, a green and efficient biosynthetical technique was reported for preparing cadmium sulfide (CdS) quantum dots, in which Escherichia coli (E. coli) was chosen as a biomatrix. Fluorescence emission spectra and fluorescent microscopic photographs revealed that as-produced CdS quantum dots had an optimum fluorescence emission peak located at 470nm and emitted a blue-green fluorescence under ultraviolet excitation. After extracted from bacterial cells and located the nanocrystals' foci in vivo, the CdS quantum dots showed a uniform size distribution by transmission electron microscope. Through the systematical investigation of the biosynthetic conditions, including culture medium replacement, input time point of cadmium source, working concentrations of raw inorganic ions, and co-cultured time spans of bacteria and metal ions in the bio-manufacture, the results revealed that CdS quantum dots with the strongest fluorescence emission were successfully prepared when E. coli cells were in stationary phase, with the replacement of culture medium and following the incubation with 1.0×10(-3)mol/L cadmium source for 2 days. Results of antimicrobial susceptibility testing indicated that the sensitivities to eight types of antibiotics of E. coli were barely changed before and after CdS quantum dots were prepared in the mild temperature environment, though a slight fall of antibiotic resistance could be observed, suggesting hinted the proposed technique of producing quantum dots is a promising environmentally low-risk protocol.

  15. Charge transport through exciton shelves in cadmium chalcogenide quantum dot-DNA nano-bioelectronic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Samuel M.; Singh, Vivek [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Noh, Hyunwoo [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering Program and Department of Nanoengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, California 92093 (United States); Cha, Jennifer N. [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering Program and Department of Nanoengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, California 92093 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Nagpal, Prashant, E-mail: pnagpal@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder, 2445 Kittredge Loop, Boulder, Colorado 80309 (United States)

    2015-02-23

    Quantum dot (QD), or semiconductor nanocrystal, thin films are being explored for making solution-processable devices due to their size- and shape-tunable bandgap and discrete higher energy electronic states. While DNA has been extensively used for the self-assembly of nanocrystals, it has not been investigated for the simultaneous conduction of multiple energy charges or excitons via exciton shelves (ES) formed in QD-DNA nano-bioelectronic thin films. Here, we present studies on charge conduction through exciton shelves, which are formed via chemically coupled QDs and DNA, between electronic states of the QDs and the HOMO-LUMO levels in the complementary DNA nucleobases. While several challenges need to be addressed in optimizing the formation of devices using QD-DNA thin films, a higher charge collection efficiency for hot-carriers and our detailed investigations of charge transport mechanism in these thin films highlight their potential for applications in nano-bioelectronic devices and biological transducers.

  16. Influence of the temperature on the synthesis of CdS quantum dots stabilized with poly (vinil alcohol); Influencia da temperatura na sintese de pontos quanticos de sulfeto de cadmio estabilizados por poli (alcool vinilico)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Semiconductor nanoparticles (Quantum Dots, QDs) have been the subject of recent research by presenting quantum properties. This property has stimulated the study of these particles in biological applications such as bookmarks, which creates the necessity of using different synthesis routes resulting in biocompatible systems. Thus, this study aimed to evaluate the effect of temperature on the properties of QDs cadmium sulfide, aqueous route using poly (vinyl alcohol), a biocompatible polymer, such as stabilizing agent. The characterization of particles produced was performed by UV-Vis spectroscopy and photoluminescence (PL) spectra for obtaining the absorption and emission, respectively and Transmission microscopy (TEM) for analysis of the diameter of the nanocrystals. (author)

  17. Encapsulation of cadmium selenide quantum dots using a self-assembling nanoemulsion (SANE) reduces their in vitro toxicity.

    Science.gov (United States)

    Edmund, Anton R; Kambalapally, Swetha; Wilson, Thomas A; Nicolosi, Robert J

    2011-02-01

    Although, nanometer-scale semi-conductor quantum dots (QDs) have attracted widespread interest in medical diagnosis and treatment, many can have intrinsic toxicities, especially those composed of CdSe, associated with their elemental composition. Using our self-assembling nanoemulsion (SANE) formulations which we have previously reported to be composed of non-toxic components, i.e., such as vegetable oil, surfactant and water, we hypothesized that their appropriate utilization would reduce the toxicity of QDs by encapsulating the CdSe QDs in our (SANE) system using a modified phase-inversion temperature (PIT) method. SANE encapsulation of the QDs did not alter their emission wavelength of 600nm which remained unchanged during the encapsulation process. In contrast, zeta potential of encapsulated QDs was reduced from -30 to -6.59 mV, which we have previously reported to be associated with beneficial properties (increased bioavailability and efficacy) for SANE-encapsulated bioactives such as pharmaceuticals. Relative to the untreated controls, the viability of HeLa cells exposed for 48 h to un-encapsulated CdSe QDs at a concentration of 115 μg/mL was 22.7±1.7% (p<0.05). In contrast, the percentage of viable HeLa cells following exposure to SANE-encapsulated CdSe QDs at the same concentration was 91.6±3.5% (p<0.05) or a 307% increase in the number of viable cells (p<0.05). When the dose of CdSe QDs was increased to 230 μg/mL, the percentage of viable HeLa cells after exposure to the un-encapsulated CdSe QDs was 16.1±1.3% compared to controls (p<0.05). In contrast, at the same increased concentration (230 μg/mL) of un-encapsulated CdSe QDs, the percentage of viable HeLa cells following exposure to SANE-encapsulated CdSe QDs was 87.9±3.3% relative to controls (p<0.05) or a 448% increase in the number of viable cells (p<0.05). Exposure of HeLa cells to a nanoblank, (nanoemulsion without QDs), showed no significant effect on cell viability (97.2±2.5%) compared to

  18. The Study of Metal Sulfide as Efficient Counter Electrodes on the Performances of CdS/CdSe/ZnS-co-sensitized Hierarchical TiO2 Sphere Quantum Dot Solar Cells.

    Science.gov (United States)

    Buatong, Nattha; Tang, I-Ming; Pon-On, Weeraphat

    2017-12-01

    The effects of using different counter electrode metal sulfides on the performances of solar cells made with CdS/CdSe/ZnS quantum dots co-sensitized onto hierarchical TiO2 spheres (HTSs) used as photo-electrode are reported. The HTS in the QDSSCs is composed of an assembly of numerous TiO2 spheres made by the solvolthermal method. The photoelectrical performance of HTS/CdS/CdSe/ZnS coupled to CuS or to Cu2ZnSn(S1 - x Se x )4 with x = 0, 0.5, or 1.0 counter electrodes (CEs) were compared to those coupled to Pt CE. The HTS/CdS/CdSe/ZnS coupled to the CuS CE showed the highest power conversion efficiency η (of 3.46%). The efficiencies η of 1.88, 2.64, and 2.06% were obtained for CZTS (x = 0), CZTS0.5Se0.5 (x = 0.5), and CZTSe (x = 1), respectively. These are significantly higher than those using a standard Pt CE (η = 0.37%). These higher efficiencies are the results of the higher electrocatalytic activities when the metal sulfide CEs are used.

  19. Model microcavity laser with CdSe/CdS quantum dots as lasing media

    Science.gov (United States)

    Naveed, H. B.; Popov, S.; Shafique, M.

    2016-02-01

    A model is established for a microcavity laser with cadmium selenium/cadmium sulfide (CdSe/CdS) core/shell quantum dots (QDs) as a lasing medium. The research was organised to develop and solve the rate equations for the above mentioned microcavity laser to calculate the output parameters during lasing. Using time-resolved fluorescence spectroscopy, the radiative life time of the lasing medium was measured along with its fluorescence and absorption spectra. A model is also established on the basis of the segment contact method (SCM) to demonstrate the threshold gain profile using the absorption spectrum of CdSe/CdS core/shell type-II QDs residing in the cavity. A laser cavity of size 1 μm was pumped with an optical source (532 nm) to achieve an optimised laser peak at 470 nm.

  20. Recombination barrier layers in solid-state quantum dot-sensitized solar cells

    KAUST Repository

    Roelofs, Katherine E.

    2012-06-01

    By replacing the dye in the dye-sensitized solar cell design with semiconductor quantum dots as the light-absorbing material, solid-state quantum dot-sensitized solar cells (ss-QDSSCs) were fabricated. Cadmium sulfide quantum dots (QDs) were grown in situ by successive ion layer adsorption and reaction (SILAR). Aluminum oxide recombination barrier layers were deposited by atomic layer deposition (ALD) at the TiO2/hole-conductor interface. For low numbers of ALD cycles, the Al2O3 barrier layer increased open circuit voltage, causing an increase in device efficiency. For thicker Al2O3 barrier layers, photocurrent decreased substantially, leading to a decrease in device efficiency. © 2012 IEEE.

  1. Thermal Decomposition Based Synthesis of Ag-In-S/ZnS Quantum Dots and Their Chlorotoxin-Modified Micelles for Brain Tumor Cell Targeting

    OpenAIRE

    Chen, Siqi; Ahmadiantehrani, Mojtaba; Publicover, Nelson G.; Hunter, Kenneth W.; Zhu, Xiaoshan

    2015-01-01

    Cadmium-free silver-indium-sulfide (Ag-In-S or AIS) chalcopyrite quantum dots (QDs) as well as their core-shell structures (AIS/ZnS QDs) are being paid significant attention in biomedical applications because of their low toxicity and excellent optical properties. Here we report a simple and safe synthetic system to prepare high quality AIS and AIS/ZnS QDs using thermal decomposition. The synthetic system simply involves heating a mixture of silver acetate, indium acetate, and oleic acid in d...

  2. Direct water-phase synthesis of lead sulfide quantum dots encapsulated by β-lactoglobulin for in vivo second near infrared window imaging with reduced toxicity.

    Science.gov (United States)

    Chen, Jun; Kong, Yifei; Wang, Wei; Fang, Hongwei; Wo, Yan; Zhou, Dejian; Wu, Ziying; Li, Yunxia; Chen, Shiyi

    2016-03-14

    Compared to conventional fluorescence imaging in the visible (400-700 nm) and NIR-I regions (700-900 nm), optical fluorescence imaging in the second near infrared window (NIR-II, 1000-1400 nm) offers reduced photon scattering, deeper tissue penetration and lower auto-fluorescence. Despite excellent imaging capabilities, current NIR-II probes have not yet reached their full potential due to weak quantum yield, low water solubility and suboptimal biocompatibility. To address these problems, we report herein a new NIR-II fluorescent PbS quantum dots (QDs) that are fabricated in water using β-lactoglobulin (LG) as a biological template. The LG-PbS QDs exhibit satisfactory dispersibility, relatively high quantum yield and favorable biocompatibility, and therefore are suitable for high-resolution in vivo imaging applications.

  3. Quantum

    CERN Document Server

    Al-Khalili, Jim

    2003-01-01

    In this lively look at quantum science, a physicist takes you on an entertaining and enlightening journey through the basics of subatomic physics. Along the way, he examines the paradox of quantum mechanics--beautifully mathematical in theory but confoundingly unpredictable in the real world. Marvel at the Dual Slit experiment as a tiny atom passes through two separate openings at the same time. Ponder the peculiar communication of quantum particles, which can remain in touch no matter how far apart. Join the genius jewel thief as he carries out a quantum measurement on a diamond without ever touching the object in question. Baffle yourself with the bizzareness of quantum tunneling, the equivalent of traveling partway up a hill, only to disappear then reappear traveling down the opposite side. With its clean, colorful layout and conversational tone, this text will hook you into the conundrum that is quantum mechanics.

  4. Cadmium and zinc relationships.

    Science.gov (United States)

    Elinder, C G; Piscator, M

    1978-08-01

    Cadmium and zinc concentrations in kidney and liver have been measured under different exposure situations in different species including man. The results show that zinc increases almost equimolarly with cadmium in kidney after long-term low-level exposure to cadmium, e.g., in man, horse, pig, and lamb. In contrast, the increase of zinc follows that of cadmium to only a limited extent, e.g., in guinea pig, rabbit, rat, mouse, and chicks. In liver, the cadmium--zinc relationship seems to be reversed in such a way that zinc increases with cadmium more markedly in laboratory animals than in higher mammals. These differences between cadmium and zinc relationships in humans and large farm animals and those in commonly used laboratory animals must be considered carefully before experimental data on cadmium and zinc relationships in laboratory animals can be extrapolated to humans.

  5. Process for removing and detoxifying cadmium from scrap metal including mixed waste

    Energy Technology Data Exchange (ETDEWEB)

    Kronberg, J.W.

    1994-07-01

    Cadmium-bearing scrap from nuclear applications, such as neutron shielding and reactor control and safety rods, must usually be handled as mixed waste since it is radioactive and the cadmium in it is both leachable and highly toxic. Removing the cadmium from this scrap, and converting it to a nonleachable and minimally radioactive form, would greatly simplify disposal or recycling. A process now under development will do this by shredding the scrap; leaching it with reagents which selectively dissolve out the cadmium; reprecipitating the cadmium as its highly insoluble sulfide; then fusing the sulfide into a glassy matrix to bring its leachability below EPA limits before disposal. Alternatively, the cadmium may be recovered for reuse. A particular advantage of the process is that all reagents (except the glass frit) can easily be recovered and reused in a nearly closed cycle, minimizing the risk of radioactive release. The process does not harm common metals such as aluminum, iron and stainless steel, and is also applicable to non-nuclear cadmium-bearing scrap such as nickel-cadmium batteries.

  6. Influence of poly(vinyl alcohol) degree of hydrolysis in the production of quantum dots for bioconjugation; Influencia do grau de hidrolise do poli(alcool vinilico) na obtencao de pontos quanticos para bioconjugacao

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Quantum dots, also known as semiconducting nanoparticle, are promising zero-dimensional advanced materials because of their nanoscale size and their quantum confinement properties. One of the fastest moving and most exciting interfaces of nanotechnology is the use of QDs in medicine, cell, and molecular biology, especially as biological detectors. In the case of these applications, it is crucial QDs synthesis based on aqueous routes and biocompatible stabilizers. In this sense, the main goal of this study was to obtain cadmium sulfide quantum dots from aqueous route using poly(vinyl alcohol), PVA, as capping agent, evaluating the influence of polymer degree of hydrolysis in nanoparticle formation and stabilization. UV-Vis spectroscopy was used to detect quantum dots production and size. The results have shown that PVA degree of hydrolysis is a crucial parameter to be controlled in order to obtain semiconducting nanoparticles in aqueous media for conjugation with biomolecules such as immunoglobulins, proteins, DNS, and oligonucleotides. (author)

  7. Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2015-09-01

    Full Text Available The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2 of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

  8. Effect of Mn Doping on Properties of CdS Quantum Dot-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Tianxing Li

    2014-01-01

    Full Text Available Quantum dot-sensitized solar cells (QDSSCs have received extensive attention in recent years due to their higher theoretical conversion efficiency and lower production costs. However, the photoelectric conversion efficiency of QDSSCs is still lower than the DSSCs because of the severe recombination of electrons of quantum dots conduction band. In order to improve the photoelectric conversion efficiency of QDSSCs, impurity element Mn2+ is doped into the precursor solution of cadmium sulfide (CdS. By optimizing the experimental parameters, the photoelectric conversion efficiency of QDSSCs can be greatly improved. For the deposition of a fixed number of six times, the photoelectric conversion efficiency shows the maximum value (1.51% at the doped ratio of 1 : 10.

  9. Dielectric and Thermal Properties of Transformer Oil Modified by Semiconductive CdS Quantum Dots

    Science.gov (United States)

    Abd-Elhady, Amr M.; Ibrahim, Mohamed E.; Taha, T. A.; Izzularab, Mohamed A.

    2016-10-01

    In this paper, modified transformer oil semiconductor quantum dots (QDs) are presented. Cadmium sulfide (CdS) quantum dots of radius 4.5 nm with a hexagonal crystal structure are added to transformer oil to improve its dielectric and thermal properties. CdS QDs modified oil is prepared considering different filler loading levels. Alternating current breakdown voltages of the transformer oil samples before and after the modification are measured based on American Society for Testing and Materials D1816 standard. The relative permittivity and dissipation factor are measured for all samples. Also, thermal properties of the oil samples are experimentally evaluated according to the temperature change measurement considering heating and cooling processes. The results show significant improvements in dielectric and thermal properties of the modified transformer oil, as well as an increase in the breakdown strength by about 81% in comparison to the base transformer oil.

  10. Preparation of SnS/CdS Co-sensitized TiO2 Photoelectrodes for Quantum Dots Sensitized Solar Cells

    Science.gov (United States)

    Xie, Yu-Long; Song, Ping; Zhao, Su-Qing

    2016-10-01

    TiO2 porous films have been prepared by electrophoresis deposition method, while tin sulfide (SnS) and cadmium sulfide quantum dots (QDs) have been deposited by a simple and inexpensive successive ionic layer adsorption and reaction method. The CdS and SnS QDs modifications expanded the photoresponse range of TiO2 nanoparticles from the ultraviolet region to visible range. Such prepared SnS/CdS/TiO2 films were used as photo-anodes to assemble QDs sensitized solar cells with I-/I3 - liquid electrolyte and Pt-coated fluorine-doped tin oxide glass counter electrode. The best resulting cells had an open circuit voltage of 520 mV, a short circuit current density of 2.972 mA cm-2, a fill factor of 0.61, and with a conversion efficiency of 0.936%.

  11. The Magic-Size Nanocluster (CdSe)34 as a Low-Temperature Nucleant for Cadmium Selenide Nanocrystals; Room-Temperature Growth of Crystalline Quantum Platelets

    OpenAIRE

    Wang, Yuanyuan; Zhang, Ying; Wang, Fudong; Giblin, Daryl E.; Hoy, Jessica; Rohrs, Henry W.; Loomis, Richard A.; Buhro, William E.

    2014-01-01

    Reaction of Cd(OAc)2·2H2O and selenourea in primary-amine/secondary-amine cosolvent mixtures affords crystalline CdSe quantum platelets at room temperature. Their crystallinity is established by X-ray diffraction analysis (XRD), high-resolution transmission electron microscopy (TEM), and their sharp extinction and photoluminescence spectra. Reaction monitoring establishes the magic-size nanocluster (CdSe)34 to be a key intermediate in the growth process, which converts to CdSe quantum platele...

  12. Interstellar hydrogen sulfide.

    Science.gov (United States)

    Thaddeus, P.; Kutner, M. L.; Penzias, A. A.; Wilson, R. W.; Jefferts, K. B.

    1972-01-01

    Hydrogen sulfide has been detected in seven Galactic sources by observation of a single line corresponding to the rotational transition from the 1(sub 10) to the 1(sub 01) levels at 168.7 GHz. The observations show that hydrogen sulfide is only a moderately common interstellar molecule comparable in abundance to H2CO and CS, but somewhat less abundant than HCN and much less abundant than CO.

  13. Cadmium and zinc relationships

    Energy Technology Data Exchange (ETDEWEB)

    Elinder, C.; Piscator, M.

    1978-08-01

    Higher mammals, such as homo sapiens, accumulate zinc in kidney cortex almost equimolarly with cadmium. A different pattern seems to be present in liverthere is a limited increase of zinc in two species of large farm animals compared with a marked increase in the laboratory. In large farm animals, an equimolar increase of zinc with cadmium in renal cortex seems to indicate that the form of metallothionein that binds equal amounts of cadmium and zinc in present. Differences in cadmium and zinc relationships in large animals and humans compared with laboratory animals must be carefully considered. (4 graphs, 26 references)

  14. Copper Sulfide Catalyzed Porous Fluorine-Doped Tin Oxide Counter Electrode for Quantum Dot-Sensitized Solar Cells with High Fill Factor

    Directory of Open Access Journals (Sweden)

    Satoshi Koyasu

    2017-01-01

    Full Text Available The performance of quantum dot-sensitized solar cell (QDSSC is mainly limited by chemical reactions at the interface of the counter electrode. Generally, the fill factor (FF of QDSSCs is very low because of large charge transfer resistance at the interface between the counter electrode and electrolyte solution containing redox couples. In the present research, we demonstrate the improvement of the resistance by optimization of surface area and amount of catalyst of the counter electrode. A facile chemical synthesis was used to fabricate a composite counter electrode consisting of fluorine-doped tin oxide (FTO powder and CuS nanoparticles. The introduction of a sputtered gold layer at the interface of the porous-FTO layer and underlying glass substrate also markedly reduced the resistance of the counter electrode. As a result, we could reduce the charge transfer resistance and the series resistance, which were 2.5 [Ω] and 6.0 [Ω], respectively. This solar cell device, which was fabricated with the presently designed porous-FTO counter electrode as the cathode and a PbS-modified electrode as the photoanode, exhibited a FF of 58%, which is the highest among PbS-based QDSSCs reported to date.

  15. Investigation of cadmium resistance in an Alcaligenes sp

    Energy Technology Data Exchange (ETDEWEB)

    McEntee, J.D.; Woodrow, J.R.; Quirk, A.V.

    1986-03-01

    The mechanisms of metal resistance of a cadmium-resistant Alcaligenes sp. were studied. Growth in a defined medium was unaffected by cadmium at concentrations up to 0.1 mM, while at concentrations up to 2.5 mM, growth occurred after an extended lag phase. The increase in length of the lag phase was abolished by repeated subculturing at these higher concentrations. However, subculture in the absence of cadmium reversed the adaptation process. Plasmid DNA was not detected in adapted cells, suggesting that adaptation is not plasmid mediated. Increased sulfide production in response to cadmium was observed, although the levels were too low to account fully for cadmium resistance. Adaptation of cells to cadmium resulted in the appearance of a major new membrane preparation. This protein was induced at cadmium concentrations of 0.1 mM and above, but below this level the protein was absent. The onset of growth at concentrations above 0.1 mM was coincident with the appearance of this protein, which was also induced by zinc (0.4 mM) but not by manganese or nickel. The protein was only solubilized by a sodium dodecyl sulfate-2-mercaptoethanol mixture. Similar solubility properties were shown by a second major membrane protein (molecular weight, 33,000). These two proteins proved to be similar by peptide-mapping experiments and amino acid analysis. The appearance of the 34,500-molecular-weight protein and its possible role in cadmium resistance are discussed.

  16. Single Crystalline Cadmium Sulfide Nanowires with Branched Structure

    Directory of Open Access Journals (Sweden)

    Lu Qingyi

    2009-01-01

    Full Text Available Abstract In this article, we report the synthesis of branched single crystal CdS nanowires. This branched CdS nanostructure is prepared by a simple surfactant-directing method, which is of particular interest as it uses readily available reagents and provides a convenient route to high-yield single crystal nanowires but with branched shape. These branched nanowires have an average diameter of about 40 nm and length up to several micrometers. A possible mechanism has been proposed and the addition of surfactant dodecylthiol into the two mixed-solvents would play an importance effect on the structure of the product. Based on the mechanism, by controlling the synthesis conditions, such as the ratios between the surfactant, inorganic solvent, and organic solvent, other kinds of nanostructures based on CdS nanowires were also prepared. Photoluminescence (PL measurement reveals that the branched CdS nanowires have a strong emission at about 700 nm which might be due to its special structure.

  17. Nanostructured Cadmium Sulfide: Sonochemical Synthesis, Optical Properties and Formation Process

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution ofCdCl2, Na2S2O3 and (CH3)2CHOH in Ar atmosphere at room temperature. The results of a detailed investigationwith X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and optical absorption spec-troscopy are reported. A clearly red shift of the absorption edge and a broad absorption band related to the surfacestates of nanoparticles have been observed in the optical absorption spectra with the increasing of CdS particle size.The mechanisms of the CdS nanoparticle formation and size growth during sonochemical irradiation were discussed.This convenient method is found to be an efficient way to produce other chalcogenides as well.

  18. Solid state, transparent, cadmium sulfide-polymer nanocomposites

    Science.gov (United States)

    Kothurkar, Nikhil K.

    This dissertation deals with the preparation and characterization of solid state, transparent CdS-polymer nanocomposites for potential applications in optical limiting, lenses and photovoltaics. The focus of this research was controlling CdS aggregation to obtain 1 mm thick, films with a transmittance >85%. CdS-polysulfone nanocomposites gave transparent sols using thiol-capping agents however solid films obtained, were translucent to opaque. CdS-epoxy nanocomposites gave 1 mm thick films with >85% transmittance. Oligomeric polyoxypropylene diamine stabilizers were used to shield the inter particle forces and increase the viscosity of the medium to give air stable sols. Films were obtained by curing the CdS sols with an epoxy resin system. The band edge of the nanocomposites showed a shoulder corresponding to the absorption from the CdS particles. A majority of small amorphous and non-stoichiometric (richer in Cd) particles epoxy system depends on a number of factors including temperature, stabilizer concentration, stabilizer molar mass and US concentration. Effective aggregation control yields transparent films. Factors affecting the band edge and transparency of the films were detected and regression models were fitted to the data. Temperature, stabilizer concentration and CdS concentration had significant effects on the band edge and transparency. Interactions between temperature-stabilizer concentration and temperature-CdS concentration had significant effects on the band edge. Band edge tunability with temperature was demonstrated. An attempt to estimate the particle size from the band edge was made but owing absence of any suitable theoretical models, an accurate estimate was not possible. However a rough estimate was provided. High concentration CdS-epoxy thin and thick films containing up to 21% US were synthesized using two different methods. High transparency of about 85% was obtained in some of them.

  19. Harnessing Sun’s Energy with Quantum Dots Based Next Generation Solar Cell

    Science.gov (United States)

    Halim, Mohammad A.

    2012-01-01

    Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal) and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun’s broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%.

  20. Harnessing Sun's Energy with Quantum Dots Based Next Generation Solar Cell.

    Science.gov (United States)

    Halim, Mohammad A

    2012-12-27

    Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal) and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun's broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%.

  1. Harnessing Sun’s Energy with Quantum Dots Based Next Generation Solar Cell

    Directory of Open Access Journals (Sweden)

    Mohammad A. Halim

    2012-12-01

    Full Text Available Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun’s broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%.

  2. 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.

  3. An easy shortcut synthesis of size-controlled bismuth nanoparticles and their use in the SLS growth of high-quality colloidal cadmium selenide quantum wires.

    Science.gov (United States)

    Wang, Fudong; Buhro, William E

    2010-02-22

    An easy shortcut synthesis of thermally stable, near-monodisperse Bi nanoparticles from BiCl(3) and Na[N(SiMe(3))(2)] is described. The diameters of the Bi nanoparticles are controlled in the range of 4-29 nm by varying the amounts of BiCl(3) and Na[N(SiMe(3))(2)] employed. Standard deviations in their diameter distributions are 5-15% of the mean diameters, consistent with near monodispersity. These Bi nanoparticles are shown to be the best currently available catalysts for the solution-liquid-solid (SLS) growth of high-quality CdSe quantum wires.

  4. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Dezhao, Liu; Hansen, Michael Jørgen;

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  5. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen;

    2012-01-01

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  6. Cysteamine capped CdS quantum dots as a fluorescence sensor for the determination of copper ion exploiting fluorescence enhancement and long-wave spectral shifts

    Science.gov (United States)

    Boonmee, Chanida; Noipa, Tuanjai; Tuntulani, Thawatchai; Ngeontae, Wittaya

    2016-12-01

    We described a turn-on fluorescence sensor for the determination of Cu2 + ions, utilizing the quantum confinement effect of cadmium sulfide quantum dots capped with cysteamine (Cys-CdS QDs). The fluorescence intensity of the Cys-CdS QDs was both enhanced and red shifted (from blue-green to yellow) in the presence of Cu2 +. Fluorescence enhancement was linearly proportional to the concentration of Cu2 + in the concentration range 2 to 10 μM. Other cations at the same concentration level did not significantly change the intensity and spectral maxima of Cys-CdS QDs, except Ag+. The limit of detection was 1.5 μM. The sensor was applied to the determination of Cu2 + in (spiked) real water samples and gave satisfactory results, with recoveries ranging from 96.7 to 108.2%, and with RSDs ranging from 0.3 to 2.6%.

  7. Ligand exchange on the surface of cadmium telluride quantum dots with fluorosurfactant-capped gold nanoparticles: synthesis, characterization and toxicity evaluation.

    Science.gov (United States)

    Wang, Lingyun; Zhang, Hongxia; Lu, Chao; Zhao, Lixia

    2014-01-01

    CdTe quantum dots (QDs) can provide high-intensity and photostable luminescent signals when they are used as labeling materials for sensing trace amounts of bioanalytes. However, a major concern is whether the capping ligands of CdTe QDs cause toxic effects in living systems. In the current study, we address this problem through the complete ligand transformation of CdTe QDs from toxic thiolglycolic acid (TGA) to green citrate, which is attributed to the Cd-S bond breaking and the Au-S bond formation. The highly efficient depletion of S atom from the surface of the CdTe QDs occurs after the addition of fluorosurfactant (FSN)-capped gold nanoparticles into TGA-capped CdTe QDs, accompanying with the rapid aggregation of FSN-capped gold nanoparticles via noncrosslinking mechanism in the presence of high salt. After the ligand transformation, negligible differences are observed on both photoluminescence spectra and luminescent quantum yield. In addition, the cytotoxicity of the original and new-born CdTe QDs is detected by measuring cell viability after the nanoparticle treatment. In comparison with the original TGA-capped QDs, the new-born CdTe QDs can induce minimal cytotoxicity against human hepatocellular liver carcinoma (HepG2) cells even at high dosages. Our study indicates that the extremely simple method herein opens up novel pathways for the synthesis of green CdTe QDs, and the as-prepared citrate-capped CdTe QDs might have great potential for biological labeling and imaging applications.

  8. Subcellular partitioning kinetics, metallothionein response and oxidative damage in the marine mussel Mytilus galloprovincialis exposed to cadmium-based quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Thiago Lopes [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Gomes, Tânia [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo (Norway); Durigon, Emerson Giuliani [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Bebianno, Maria João, E-mail: mbebian@ualg.pt [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2016-06-01

    The environmental health impact of metal-based nanomaterials is of emerging concern, but their metabolism and detoxification pathways in marine bioindicator species remain unclear. This study investigated the role of subcellular partitioning kinetics, metallothioneins (MTs) response and oxidative damage (lipid peroxidation – LPO) in the marine mussel Mytilus galloprovincialis exposed to CdTe quantum dots (QDs) in comparison with its dissolved counterpart. Mussels were exposed to QDs and dissolved Cd for 21 days at 10 μg Cd L{sup −1} followed by a 50 days depuration. Higher Cd concentrations were detected in fractions containing mitochondria, nucleus and lysosomes, suggesting potential subcellular targets of QDs toxicity in mussel tissues. Tissue specific metabolism patterns were observed in mussels exposed to both Cd forms. Although MT levels were directly associated with Cd in both forms, QDs subcellular partitioning is linked to biologically active metal (BAM), but no increase in LPO occurred, while in the case of dissolved Cd levels are in the biologically detoxified metal (BDM) form, indicating nano-specific effects. Mussel gills showed lower detoxification capability of QDs, while the digestive gland is the major tissue for storage and detoxification of both Cd forms. Both mussel tissues were unable to completely eliminate the Cd accumulated in the QDs form (estimated half-life time > 50 days), highlighting the potential source of Cd and QDs toxicity for human and environmental health. Results indicate tissue specific metabolism patterns and nano-specific effects in marine mussel exposed to QDs. - Highlights: • Subcellular partitioning and MT response are Cd form, tissue and time dependent. • Tissue specific metabolism of Cd-based quantum dots (QDs) in marine mussels. • QDs are slower biologically detoxified when compared to dissolved Cd. • Subcellular partitioning and biomarker responses indicate nano-specific effects. • Subcellular

  9. Imaging pancreatic cancer using bioconjugated InP quantum dots.

    Science.gov (United States)

    Yong, Ken-Tye; Ding, Hong; Roy, Indrajit; Law, Wing-Cheung; Bergey, Earl J; Maitra, Anirban; Prasad, Paras N

    2009-03-24

    In this paper, we report the successful use of non-cadmium-based quantum dots (QDs) as highly efficient and nontoxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulfide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in nonaqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjugation with pancreatic cancer specific monoclonal antibodies, such as anticlaudin 4 and antiprostate stem cell antigen (anti-PSCA), to the functionalized InP/ZnS QDs, allowed specific in vitro targeting of pancreatic cancer cell lines (both immortalized and low passage ones). The receptor-mediated delivery of the bioconjugates was further confirmed by the observation of poor in vitro targeting in nonpancreatic cancer based cell lines which are negative for the claudin-4-receptor. These observations suggest the immense potential of InP/ZnS QDs as non-cadmium-based safe and efficient optical imaging nanoprobes in diagnostic imaging, particularly for early detection of cancer.

  10. Luminescence and bio-imaging response of thio-glycolic acid (TGA) and sodium dodecyl sulfate (SDS)-coated fluorescent cadmium selenide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Runjun; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

    2015-05-15

    We demonstrate the usefulness of surfactant coated CdSe quantum dots in bio-imaging applications after evaluating their steady state and time resolved emission responses. The surfactant coated QDs, with the respective sizes of ~14 nm and 10 nm are synthesized considering two different types of coating agents, namely, thio-glycolic acid (TGA) and sodium dodecyl sulfate (SDS). The steady state luminescence response is characterized by both near band edge (NBE) and defect-related emissions, but with a strong dependency on the nature of surfactant coating. Time resolved photoluminescence (TR-PL) studies have revealed bi-exponential characteristics with CdSe–TGA QDs exhibiting longer life time decay parameters than those of CdSe–SDS QDs. To be specific, the fast (τ{sub 1}) and the slow (τ{sub 2}) components are characterized by ~10 and 30 times larger values in the former than the latter case. In the FT-IR spectra, several stretching and bending vibrations are observed to be adequately influenced by the nature of surfactant coating. The availability of plentiful Na{sup +} counter ions around SDS coated QDs, as evident from the FT-IR spectroscopy studies, can also be responsible for obtaining reduced size of the QDs. In contrast, Raman active modes are apparently distinguishable in TGA coated QDs, with LO and TO mode positions significantly blue-shifted from the bulk values. While attributing to the intense defect mediated emission of TGA coated QDs, the effect of TGA coating presented a stronger fluorescence imaging capability over the SDS coated ones. A detailed assessment of fluorescent counts, as a basis of bio-imaging response, is being discussed on a comparative basis. - Highlights: • Fluorescent CdSe quantum dots are synthesized with two different kinds of surfactant coatings. • Time resolved photoluminescence (TR-PL) studies have revealed bi-exponential decay characteristics. • Both slow and fast decay parameters are found to be longer in CdSe QDs

  11. In vivo biodistribution and behavior of CdTe/ZnS quantum dots.

    Science.gov (United States)

    Zhao, Yan; Zhang, Yue; Qin, Gaofeng; Cheng, Jinjun; Zeng, Wenhao; Liu, Shuchen; Kong, Hui; Wang, Xueqian; Wang, Qingguo; Qu, Huihua

    2017-01-01

    The unique features of quantum dots (QDs) make them desirable fluorescent tags for cell and developmental biology applications that require long-term, multitarget, and highly sensitive imaging. In this work, we imaged fluorescent cadmium telluride/zinc sulfide (CdTe/ZnS) QDs in organs, tissues, and cells, and analyzed the mechanism of their lymphatic uptake and cellular distribution. We observed that the fluorescent CdTe/ZnS QDs were internalized by lymph nodes in four cell lines from different tissue sources. We obtained the fluorescence intensity-QD concentrations curve by quantitative analysis. Our results demonstrate that cells containing QDs can complete mitosis normally and that distribution of QDs was uniform across cell types and involved the vesicular transport system, including the endoplasmic reticulum. This capacity for CdTe/ZnS QD targeting provides insights into the applicability and limitations of fluorescent QDs for imaging biological specimens.

  12. Enhanced Performance of DSSCs Based on the Insertion Energy Level of CdS Quantum Dots

    Directory of Open Access Journals (Sweden)

    Xiaoping Zou

    2014-01-01

    Full Text Available Cadmium sulfide (CdS quantum dots (QDs are assembled onto the TiO2 films by chemical bath deposition method (CBD. And the QDs size is controlled by the times of CBD cycles. They are characterized by UV-visible absorption. To avoid the photo corrosion and electrolyte corrosion, CdS and N719 are sequentially assembled onto the nanocrystalline TiO2 films to prepare a CdS/N719 cosensitized photo electrode for the dye-sensitized solar cells. In the structure of TiO2/CdS/N719 electrode, the reorganization of energy levels between CdS and N719 forms a stepwise structure of band-edge levels which is advantageous to the electron injection and hole recovery of CdS and N719 QDs. The open circuit voltage (Voc, short circuit current density (Jsc, and efficiency are increased.

  13. High efficiency thin film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.; Chu, Shirley S.; Britt, J.; Chen, G.; Ferekides, C.; Schultz, N.; Wang, C.; Wu, C. Q.

    1992-12-01

    Cadmium sulfide (CdS), grown from an aqueous solution, and zinc oxide (ZnO), cadmium zinc sulfide (Cd1-xZnxS), and zinc selenide (ZnSe), deposited by metalorganic chemical vapor deposition (MOCVD), have been used as the window for thin film cadmium telluride (CdTe) solar cells. Thin film solar cells were prepared by the successive deposition of the window and p-CdTe (by MOCVD and close-spaced sublimation, CSS) on SnO2:F/glass substrates. CdS/CdTe(CSS) solar cells show considerably better characteristics than CdS/CdTe(MOCVD) solar cells because of the better microstructure of CSS CdTe films. Total area conversion efficiency of 14.6%, verified by the National Renewable Energy Laboratory, has been achieved for solar cells of about 1 cm2 area. Solar cell prepared by using ZnO, ZnSe, or Cd1-xZnxS as window have significantly lower photovoltage than CdS/CdTe solar cells.

  14. 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.

  15. Subcellular partitioning kinetics, metallothionein response and oxidative damage in the marine mussel Mytilus galloprovincialis exposed to cadmium-based quantum dots.

    Science.gov (United States)

    Rocha, Thiago Lopes; Gomes, Tânia; Durigon, Emerson Giuliani; Bebianno, Maria João

    2016-06-01

    The environmental health impact of metal-based nanomaterials is of emerging concern, but their metabolism and detoxification pathways in marine bioindicator species remain unclear. This study investigated the role of subcellular partitioning kinetics, metallothioneins (MTs) response and oxidative damage (lipid peroxidation - LPO) in the marine mussel Mytilus galloprovincialis exposed to CdTe quantum dots (QDs) in comparison with its dissolved counterpart. Mussels were exposed to QDs and dissolved Cd for 21 days at 10 μg Cd L(-1) followed by a 50 days depuration. Higher Cd concentrations were detected in fractions containing mitochondria, nucleus and lysosomes, suggesting potential subcellular targets of QDs toxicity in mussel tissues. Tissue specific metabolism patterns were observed in mussels exposed to both Cd forms. Although MT levels were directly associated with Cd in both forms, QDs subcellular partitioning is linked to biologically active metal (BAM), but no increase in LPO occurred, while in the case of dissolved Cd levels are in the biologically detoxified metal (BDM) form, indicating nano-specific effects. Mussel gills showed lower detoxification capability of QDs, while the digestive gland is the major tissue for storage and detoxification of both Cd forms. Both mussel tissues were unable to completely eliminate the Cd accumulated in the QDs form (estimated half-life time>50 days), highlighting the potential source of Cd and QDs toxicity for human and environmental health. Results indicate tissue specific metabolism patterns and nano-specific effects in marine mussel exposed to QDs.

  16. Enhanced fluorescence, morphological and thermal properties of CdSe/ZnS quantum dots incorporated in silicone resin.

    Science.gov (United States)

    Trung, Nguyen Ngoc; Luu, Quynh-Phuong; Son, Bui Thanh; Sinh, Le Hoang; Bae, Jin-Young

    2013-01-01

    Our research focused on the morphological and optical properties of core/shell cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots incorporated in silicone resin. After dispersing ligand-coated quantum dots into Dow Corning two-component silicone resins (OE6630A and OE6630B at 1:4 mixing ratio by weight), the resins were cured at 150 degrees C for 1.5 hours to produce the quantum dot-silicone resin nanocomposites. The optical, morphological and thermal properties of the quantum dot incorporated in silicone resin were investigated by ultraviolet-visible, fluorescence, atomic force microscopy, field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis. When the quantum dots, originally coated with trioctylamine ligand, were transferred from a chloroform solvent to methyl phenyl silicone oil and silicone resins of high viscosity, the quantum dots showed increased turbidity and lowered fluorescence intensity. Fluorescence enhancement was investigated by using various functional ligands such as poly(1, 1-dimethyl silazane) (multi-silazane), hexamethylenediamine (diamine), cysteamine (amino-thiol), triethylsilane (reactive hydrosilane), hexamethyldisilazane, nonamethyltrisilazane, octamethylcyclotetrasilazane (reactive amines). The results showed that the reactive amines were good additive ligands for enhancing the fluorescence of CdSe/ZnS quantum dots dispersed in the silicone resins, providing 1.2-2.48 Im/W and 4.2-5.56% higher luminous efficiency and photoluminescence conversion efficiency, respectively. We speculate that these reactive amines donate electrons to the surface electron traps, thereby reducing charge recombination. In addition, quantum dots aggregate to form quantum dot clusters with a relatively homogeneously dispersed in the silicone resin matrices, showing good emission properties due to surface passivation and good colloidal stability with the addition of silazane compounds to the resin

  17. Histopathological assessment and inflammatory response in the digestive gland of marine mussel Mytilus galloprovincialis exposed to cadmium-based quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Thiago Lopes [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Laboratory of Cellular Behavior, Biological Sciences Institute, Federal University of Goiás, Goiânia, Goiás (Brazil); Sabóia-Morais, Simone Maria Teixeira [Laboratory of Cellular Behavior, Biological Sciences Institute, Federal University of Goiás, Goiânia, Goiás (Brazil); Bebianno, Maria João, E-mail: mbebian@ualg.pt [CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2016-08-15

    Highlights: • Digestive gland of marine mussels is target for Cd-based QDs toxicity. • Both Cd forms increase the frequency of atrophic digestive tubules in a time dependent pattern. • QDs induce higher inflammatory responses when compared to dissolved Cd. • Multiparametric tissue-levels biomarkers show distinct mode of action in the digestive gland. - Abstract: Although tissue-level biomarkers have been widely applied in environmental toxicology studies, the knowledge using this approach in marine invertebrates exposed to engineered nanomaterials (ENMs) remains limited. This study investigated histopathological alterations and inflammatory responses induced by Cd-based quantum dots (QDs), in comparison with their dissolved counterparts, in the marine mussel Mytilus galloprovincialis. Mussels were exposed to CdTe QDs and dissolved Cd at the same concentration (10 μg Cd L{sup −1}) for 14 days and a total of 15 histopathological alterations and 17 histomorphometric parameters were analysed in the digestive gland along with the determination of histopathological condition indices (I{sub h}). A multivariate analysis showed that the mussel response to QDs was more related to exposure time, inflammatory conditions (frequency of haemocytic infiltration and granulocytomas) and changes of cell-type composition (especially the rate between basophilic and digestive cells) when compared to dissolved Cd, while the response to dissolved Cd was associated with histomorphometric parameters of the epithelium and lumen of digestive tubules and increase of the atrophic tubule frequency. Both Cd forms induced higher I{sub h} compared to unexposed mussels indicating a significant decrease in the health status of digestive gland in a Cd form and time-dependent pattern. Results indicate that the multiparametric tissue-level biomarkers in the digestive gland provide a suitable approach to assess the ecotoxicity and mode of action of metal-based ENMs in marine bivalves.

  18. Sulfide detoxification in plant mitochondria.

    Science.gov (United States)

    Birke, Hannah; Hildebrandt, Tatjana M; Wirtz, Markus; Hell, Rüdiger

    2015-01-01

    In contrast to animals, which release the signal molecule sulfide in small amounts from cysteine and its derivates, phototrophic eukaryotes generate sulfide as an essential intermediate of the sulfur assimilation pathway. Additionally, iron-sulfur cluster turnover and cyanide detoxification might contribute to the release of sulfide in mitochondria. However, sulfide is a potent inhibitor of cytochrome c oxidase in mitochondria. Thus, efficient sulfide detoxification mechanisms are required in mitochondria to ensure adequate energy production and consequently survival of the plant cell. Two enzymes have been recently described to catalyze sulfide detoxification in mitochondria of Arabidopsis thaliana, O-acetylserine(thiol)lyase C (OAS-TL C), and the sulfur dioxygenase (SDO) ethylmalonic encephalopathy protein 1 (ETHE1). Biochemical characterization of sulfide producing and consuming enzymes in mitochondria of plants is fundamental to understand the regulatory network that enables mitochondrial sulfide homeostasis under nonstressed and stressed conditions. In this chapter, we provide established protocols to determine the activity of the sulfide releasing enzyme β-cyanoalanine synthase as well as sulfide-consuming enzymes OAS-TL and SDO. Additionally, we describe a reliable and efficient method to purify OAS-TL proteins from plant material.

  19. Luminescent Properties of Graded Cadmium Sulfoselenide Electrodes Prepared from Cadmium Sulfide Substrates.

    Science.gov (United States)

    1984-09-28

    Michael K. Carpenter and Arthur B. Ellis Prepared for Publication in Journal of Electroanalytical Chemistry and Interfacial Electrochemistry Department of...Reportj * IS. SUPPLEMENTARY NOTES Prepared for publication in the Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 19. KEY WORDS

  20. Stability studies of cadmium telluride/cadmium sulfide thin film solar cells

    Science.gov (United States)

    Tetali, Bhaskar Reddy

    CdTe/CdS solar cells have shown great potential for terrestrial solar power applications. To be commercially viable they need to operate efficiently for about 30 years. CdS/CdTe solar cells fabricated at USF have shown record efficiencies upto 16.5% [46]. This research involves the study of thermal stress (TS) and light soaking (LS) on the stability of high efficiency (>10%) solar cells. The change in key electrical parameters Voc, FF, J sc, A and Jo are quantified for more than 2000 hours of stressing. The device degradation was found to increase with stress temperature for TS. Below 100°C, the changes were due to collection and recombination losses. Above 100°C, "shunting" mechanisms were found to start affecting the device performance. A fast drop in performance within the first 500 hours was observed. It is believed to be due to an increase in deep-level Cu-related defects that increase with stress temperature. Diffusion of Cu i+ ions from the back contact along CdTe grain boundaries had been previously reported [16]. An increase in light/dark J-V crossover and bulk Rs with stress time and temperature was observed. A slow degradation component attributed to Cu-related substitutional defect [23] formation/diffusion to the junction and CdS is proposed. This should compensate the CdS over time and increase its photoconductivity/resistivity. An improvement in the current collection and FF within 100 hours of LS was observed. This is possibly due to the enhancement of Cui + diffusion into the junction and CdS during LS as previously reported [16]. A reduction in light/dark J-V crossover was observed, possibly due to an increase in CdS doping and reduction in the CdS/SnO2 front contact barrier. However, a fast decrease in Voc and increase in recombination current was also observed in the first 1000 hours of LS. This is possibly due to the existence of higher concentration of Cu-related deep level defects at the junction. A larger decrease in Voc was found for LS than TS at the same operating temperature. A continuous drop in performance over time is observed for both TS and LS. The existence of a slow degradation component involving the formation/diffusion of Cu-related substitutional defects at the junction and CdS is proposed. The concentration of this defect is probably not high enough in CdS for LS samples to affect their photoconductivity and cause light/dark J-V crossover in 2000 hours.

  1. Silver-cadmium alloys: Physical and metallurgical properties. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    The bibliography contains citations concerning the metallurgical and physical properties of silver-cadmium alloys, oxides, and sulfides. The phase relationships and crystal structure of this alloy system are presented. Applications for electrical contact devices are discussed extensively. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  2. Plausible Mechanisms of Cadmium Carcinogenesis

    Science.gov (United States)

    Cadmium is a transition metal and an ubiquitous environmental and industrial pollutant. Laboratory animal studies and epidemiological studies have shown that exposure to cadmium is associated with various organ toxicities and carcinogenic effects. Several national and internation...

  3. Improved Performance of CdS/CdTe Quantum Dot-Sensitized Solar Cells Incorporating Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ho Kyeong; Park, Tae Hee; Lee, Jun Young; Yang, Jong Hee; Han, Jin Wook; Yi, Whi Kun [Hanyang University, Seoul (Korea, Republic of)

    2014-09-15

    We fabricated quantum dot-sensitized solar cells (QDSSCs) using cadmium sulfide (CdS) and cadmium telluride (CdTe) quantum dots (QDs) as sensitizers. A spin coated TiO{sub 2} nanoparticle (NP) film on tin-doped indium oxide glass and sputtered Au on fluorine-doped tin oxide glass were used as photo-anode and counter electrode, respectively. CdS QDs were deposited onto the mesoporous TiO{sub 2} layer by a successive ionic layer adsorption and reaction method. Pre-synthesized CdTe QDs were deposited onto a layer of CdS QDs using a direct adsorption technique. CdS/CdTe QDSSCs had high light harvesting ability compared with CdS or CdTe QDSSCs. QDSSCs incorporating single-walled carbon nanotubes (SWNTs), sprayed onto the substrate before deposition of the next layer or mixed with TiO{sub 2} NPs, mostly exhibited enhanced photo cell efficiency compared with the pristine cell. In particular, a maximum rate increase of 24% was obtained with the solar cell containing a TiO{sub 2} layer mixed with SWNTs.

  4. Chirality Inversion of CdSe and CdS Quantum Dots without Changing the Stereochemistry of the Capping Ligand.

    Science.gov (United States)

    Choi, Jung Kyu; Haynie, Benjamin E; Tohgha, Urice; Pap, Levente; Elliott, K Wade; Leonard, Brian M; Dzyuba, Sergei V; Varga, Krisztina; Kubelka, Jan; Balaz, Milan

    2016-03-22

    L-cysteine derivatives induce and modulate the optical activity of achiral cadmium selenide (CdSe) and cadmium sulfide (CdS) quantum dots (QDs). Remarkably, N-acetyl-L-cysteine-CdSe and L-homocysteine-CdSe as well as N-acetyl-L-cysteine-CdS and L-cysteine-CdS showed "mirror-image" circular dichroism (CD) spectra regardless of the diameter of the QDs. This is an example of the inversion of the CD signal of QDs by alteration of the ligand's structure, rather than inversion of the ligand's absolute configuration. Non-empirical quantum chemical simulations of the CD spectra were able to reproduce the experimentally observed sign patterns and demonstrate that the inversion of chirality originated from different binding arrangements of N-acetyl-L-cysteine and L-homocysteine-CdSe to the QD surface. These efforts may allow the prediction of the ligand-induced chiroptical activity of QDs by calculating the specific binding modes of the chiral capping ligands. Combined with the large pool of available chiral ligands, our work opens a robust approach to the rational design of chiral semiconducting nanomaterials.

  5. 29 CFR 1910.1027 - Cadmium.

    Science.gov (United States)

    2010-07-01

    ... battery Plate making, plate preparation 50 All other processes 15 Zinc/Cadmium refining* Cadmium refining... as an airborne concentration of cadmium of 2.5 micrograms per cubic meter of air (2.5 µg/m3... air cadmium level to which an employee is exposed means the exposure to airborne cadmium that...

  6. Fluorescence quantum efficiency of CdSe/ZnS quantum dots functionalized with amine or carboxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Pilla, Viviane, E-mail: vivianepilla@infis.ufu.br [Universidade Federal de Uberlandia (UFU), Instituto de Fisica (Brazil); Munin, Egberto [Universidade Camilo Castelo Branco (UNICASTELO), Centro de Engenharia Biomedica (Brazil)

    2012-10-15

    The thermo-optical parameters of cadmium selenide/zinc sulfide (CdSe/ZnS) core-shell quantum dots (QDs) suspended in aqueous solutions were measured using a Thermal Lens (TL) technique. TL transient measurements were performed using the mode-mismatched dual-beam (excitation and probe) configuration. A He-Ne laser at {lambda}{sub p} = 632.8 nm was used as the probe beam, and an Ar{sup +} laser (at {lambda}{sub e} = 514.5 nm) was used as the excitation beam to study the effect of the core sizes (2-4 nm) of CdSe/ZnS nanocrystals functionalized with amine (R-NH{sub 2}) or carboxyl (R-COOH) groups. The average values of the thermal diffusivity D = (1.48 {+-} 0.06) Multiplication-Sign 10{sup -3} cm{sup 2}/s obtained for QDs samples are in good agreement with the pure water solvent result. The fraction thermal load ({phi}) and radiative quantum efficiencies ({eta}) of the functionalized CdSe/ZnS QDs were determined and compared with non-functionalized CdSe/ZnS QDs. The obtained {eta} values for non-functionalized CdSe/ZnS are slightly higher than those for the QDs functionalized with amine or carboxyl groups.

  7. 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.

  8. Cadmium and cancer.

    Science.gov (United States)

    Hartwig, Andrea

    2013-01-01

    Cadmium is an established human and animal carcinogen. Most evidence is available for elevated risk for lung cancer after occupational exposure; however, associations between cadmium exposure and tumors at other locations including kidney, breast, and prostate may be relevant as well. Furthermore, enhanced cancer risk may not be restricted to comparatively high occupational exposure, but may also occur via environmental exposure, for example in areas in close proximity to zinc smelters. The underlying mechanisms are still a matter of manifold research activities. While direct interactions with DNA appear to be of minor importance, elevated levels of reactive oxygen species (ROS) have been detected in diverse experimental systems, presumably due to an inactivation of detoxifying enzymes. Also, the interference with proteins involved in the cellular response to DNA damage, the deregulation of cell growth as well as resistance to apoptosis appears to be involved in cadmium-induced carcinogenicity. Within this context, cadmium has been shown to disturb nucleotide excision repair, base excision repair, and mismatch repair. Particularly sensitive targets appear to be proteins with zinc-binding structures, present in DNA repair proteins such as XPA, PARP-1 as well as in the tumor suppressor protein p53. Whether or not these interactions are due to displacement of zinc or due to reactions with thiol groups involved in zinc complexation or in other critical positions under realistic exposure conditions remains to be elucidated. Further potential mechanisms relate to the interference with cellular redox regulation, either by enhanced generation of ROS or by reaction with thiol groups involved in the regulation of signaling pathways. Particularly the combination of these multiple mechanisms may give rise to a high degree of genomic instability evident in cadmium-adapted cells, relevant not only for tumor initiation, but also for later steps in tumor development.

  9. Nanotoxicological evaluation of oxidative responses in rat nephrocytes induced by cadmium

    Directory of Open Access Journals (Sweden)

    Trabelsi H

    2013-09-01

    Full Text Available Hamdi Trabelsi, Inès Azzouz, Soumaya Ferchichi, Olfa Tebourbi, Mohsen Sakly, Hafedh Abdelmelek Laboratory of Integrative Physiology, Faculty of Sciences of Bizerte, Carthage University, Jarzouna, Tunisia Abstract: The aim of this study was to investigate the interaction of cadmium chloride with mineral elements in rat nephrocytes in terms of the biosynthesis of nanocomplexes. The results show that selenium supplementation enhanced cadmium accumulation in kidneys. Analysis of the fluorescence revealed an increase in red fluorescence in the kidneys of rats co-exposed to cadmium and selenium. Interestingly, X-ray diffraction measurements carried out on kidney fractions of co-exposed rats point to the biosynthesis of cadmium selenide and/or sulfide nanoparticles (about 62 nm in size. Oxidative stress assays showed the ability of selenium to reduce lipid peroxidation and to restore glutathione peroxidase and superoxide dismutase activity in kidneys. Hence, cadmium complexation with selenium and sulfur at a nanoscale level could reduce oxidative stress induced by cadmium in kidneys. Keywords: nanoparticles, detoxification, oxidative stress, X-ray diffraction, fluorescence microscopy, kidneys

  10. Sulfide intrusion and detoxification in Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2014-01-01

    indicating a possible role of sulfide in the sulfur nutrition beside the detoxification function. Our results suggest different adaptations of Z. marina to reduced sediments and sulfide intrusion ranging from bacterial and chemical reoxidation of sulfide to sulfate to incorporation of sulfide into organic...

  11. Hollow glass waveguides with multilayer polystyrene and metal sulfide thin film coatings for improved infrared transmission

    Science.gov (United States)

    Johnson, Valencia S.

    2007-12-01

    The overall goal of this project was to improve transmission of infrared radiation in hollow waveguides. First, polystyrene was studied as a new dielectric material for silver-coated hollow glass waveguides. The deposition and performance of polystyrene, as a single dielectric layer, were investigated. The potential of polystyrene as the low index of refraction material in a multilayer coating was also demonstrated. Cadmium sulfide and lead sulfide were each considered as the high index material in the multilayer stack. Multilayer silver coated hollow glass waveguides can be formed using polystyrene and either cadmium sulfide or lead sulfide. These material pairs are interesting because they form a multilayer structure with high index contrast, which can significantly lower the loss of a waveguide. The deposition of lead sulfide was also optimized in this project. Lead sulfide, as a single layer dielectric coating, is an attractive material for transmission of longer wavelength radiation, especially 10.6 mum. It is also of interest for emerging applications such as metals processing by lasers because hollow waveguides with silver and lead sulfide can make a low loss waveguide. Losses as low as 0.1dB/m were achieved. The deposition of zinc sulfide and zinc selenide was also investigated in this project. They are of interest because of their small extinction coefficients at longer wavelengths and potential for use in waveguides used for materials processing. The numerous simultaneous chemical reactions occurring during deposition of these materials makes obtaining pure films difficult. Gold was evaluated as a replacement for silver as the highly reflecting metallic layer. It was considered an attractive alternative because it has greater resistance to degradation in high temperature and corrosive environments. All samples were made using an electroless process. Characterization of the samples was performed using the optical techniques of FTIR and UV

  12. Polycation-Capped CdS Quantum Dots Synthesized in Reverse Microemulsions

    Directory of Open Access Journals (Sweden)

    Karina Lemke

    2012-01-01

    Full Text Available This paper is focused on the formation and recovery of cadmium sulfide (CdS nanoparticles in two different types of polycation-modified reverse microemulsions using low molecular weight poly(diallyldimethylammonium chloride (PDADMAC and poly(ethyleneimine (PEI. Both polymers were incorporated in a quaternary w/o microemulsion consisting of water, toluene-pentanol (1 : 1, and sodium dodecyl sulfate (SDS, as well as in a ternary w/o microemulsion consisting of water, heptanol, and 3-(N,N-dimethyl-dodecylammonio-propanesulfonate (SB. UV-vis and fluorescence measurements in the microemulsion illustrate the capping effect of the polycations on the formation of the CdS quantum dots. The nanoparticles are redispersed in water and characterized by using UV-vis and fluorescence spectroscopy, in combination with dynamic light scattering. From the quaternary microemulsion, only nanoparticle aggregates of about 100 nm can be redispersed, but, from the ternary microemulsion, well-stabilized polycation-capped CdS quantum dots can be obtained. The results show that the electrostatic interactions between the polycation and the surfactant are of high relevance especially in the solvent evaporation and redispersion process. That means only that in the case of moderate polycation-surfactant interactions a redispersion of the polymer-capped CdS quantum dots without problems of aggregation is possible.

  13. A novel method for improving cerussite sulfidization

    Institute of Scientific and Technical Information of China (English)

    Qi-cheng Feng; Shu-ming Wen; Wen-juan Zhao; Qin-bo Cao; Chao L

    2016-01-01

    Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sul-fide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

  14. Fabrication of ZnO nanostructures sensitized with CdS quantum dots for photovoltaic application using a convenient solution method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huan [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Zhang, Gengmin, E-mail: zgmin@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); SIP-UCLA Institute for Technology Advancement, Suzhou 215123, Jiangsu Province (China); Yin, Jianbo [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Liang, Jia; Sun, Wentao; Shen, Ziyong [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China)

    2015-01-15

    Zinc oxide (ZnO) nanostructures sensitized with cadmium sulfide quantum dots (CdS QDs) were fabricated using a simple and inexpensive solution method. ZnO nanostructures, in the form of either nanocones or nanorods, were first grown directly from fluorine-doped tin oxide (FTO) substrates in aqueous solutions of zinc nitrate (Zn(NO{sub 3}){sub 2}) and hexamethylenetetramine (HMTA, C{sub 6}H{sub 12}N{sub 4}) under external voltages. Then, CdS QDs were attached to these ZnO nanostructures via reactions in the mixed aqueous solutions of cadmium nitrate (Cd(NO{sub 3}){sub 2}) and thioacetamide (C{sub 2}H{sub 5}NS). Photovoltaic responses were obtained from the quantum dot sensitized solar cells (QDSSCs) in which these CdS QD-covered ZnO nanostructures were employed as the photoanodes. The morphologies of the ZnO nanostructures, which could be effectively modulated via the substrate location in the solutions during the fabrication, were found to have played an important role in determining the properties of the QDSSCs.

  15. Improved performance of CdS/CdSe quantum dots sensitized solar cell by incorporation of ZnO nanoparticles/reduced graphene oxide nanocomposite as photoelectrode

    Science.gov (United States)

    Ghoreishi, F. S.; Ahmadi, V.; Samadpour, M.

    2014-12-01

    Here we present novel quantum dot sensitized solar cells (QDSSC) based on ZnO nanoparticles (NPs)/reduced graphene oxide (RGO) nanocomposite photoanodes for better light harvesting and energy conversion. Photoelectrodes are prepared by doctor blading ZnO NPs/GO nanocomposite paste on a fluorine doped tin oxide substrate which are then sintered at 450 °C to obtain ZnO NPs/RGO nanocomposites. The partial reduction of GO after thermal reduction, is studied by Fourier transform infrared and Raman spectroscopies. Cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots are deposited on the films through successive ionic layer adsorption and reaction and chemical bath deposition methods, respectively. The unique properties of ZnO NPs/RGO photoanodes, lead to a significant enhancement in the photovoltaic properties of solar cells in comparison with bare ZnO photoanodes. Current-voltage characteristics of cells are studied and the best results are obtained from ZnO NPs-RGO/CdS/CdSe with photoelectric conversion efficiency of 2.20% which is almost two times higher than cells which are made by pure ZnO NPs as photoanode (1.28%). Electrochemical impedance measurements show that the enhancement can be attributed to the increase of electron transfer rate in the ZnO NPs/RGO nanocomposite photoanode which arises from the ultrahigh electron mobility in graphene (RGO) sheets.

  16. Cadmium in Sweden - environmental risks

    Energy Technology Data Exchange (ETDEWEB)

    Parkman, H.; Iverfeldt, Aa. [Swedish Environmental Research Inst. (Sweden); Borg, H.; Lithner, G. [Stockholm Univ. (Sweden). Inst. for Applied Environmental Research

    1998-03-01

    This report aims at assessing possible effects of cadmium in the Swedish environment. Swedish soils and soft freshwater systems are, due to a generally poor buffering capacity, severely affected by acidification. In addition, the low salinity in the Baltic Sea imply a naturally poor organism structure, with some important organisms living close to their limit of physiological tolerance. Cadmium in soils is mobilized at low pH, and the availability and toxicity of cadmium in marine systems are enhanced at low salinity. The Swedish environment is therefore extra vulnerable to cadmium pollution. The average concentrations of cadmium in the forest mor layers, agricultural soils, and fresh-waters in Sweden are enhanced compared to `back-ground concentrations`, with a general increasing trend from the north to the south-west, indicating strong impact of atmospheric deposition of cadmium originating from the central parts of Europe. In Swedish sea water, total cadmium concentrations, and the fraction of bio-available `free` cadmium, generally increases with decreasing salinity. Decreased emissions of cadmium to the environment have led to decreasing atmospheric deposition during the last decade. The net accumulation of cadmium in the forest mor layer has stopped, and even started to decrease. In northern Sweden, this is due to the decreased deposition, but in southern Sweden the main reason is increased leakage of cadmium from the topsoil as a consequence of acidification. As a result, cadmium in the Swedish environments is undergoing an extended redistribution between different soil compartments, and from the soils to the aquatic systems. 90 refs, 23 figs, 2 tabs. With 3 page summary in Swedish

  17. Renal cadmium overload without nephrotoxicity.

    OpenAIRE

    1981-01-01

    A redundant nickel/cadmium battery worker was investigated for non-specific fatigue after completing five years in the industry. Sensitive techniques for in-vivo organ cadmium measurement showed a moderate accumulation in the liver but a very large concentration in the kidneys. Despite this, overall glomerular and tubular function were not impaired. It was concluded that the mechanism of proteinuria observed in some cadmium workers is obscure and not clearly related to the degree of kidney sa...

  18. Prevention of sulfide oxidation in sulfide-rich waste rock

    Science.gov (United States)

    Nyström, Elsa; Alakangas, Lena

    2015-04-01

    The ability to reduce sulfide oxidation in waste rock after mine closure is a widely researched area, but to reduce and/or inhibit the oxidation during operation is less common. Sulfide-rich (ca 30 % sulfur) waste rock, partially oxidized, was leached during unsaturated laboratory condition. Trace elements such as As and Sb were relatively high in the waste rock while other sulfide-associated elements such as Cu, Pb and Zn were low compared to common sulfide-rich waste rock. Leaching of unsaturated waste rock lowered the pH, from around six down to two, resulting in continuously increasing element concentrations during the leaching period of 272 days. The concentrations of As (65 mg/L), Cu (6.9 mg/L), Sb (1.2 mg/L), Zn (149 mg/L) and S (43 g/L) were strongly elevated at the end of the leaching period. Different alkaline industrial residues such as slag, lime kiln dust and cement kiln dust were added as solid or as liquid to the waste rock in an attempt to inhibit sulfide oxidation through neo-formed phases on sulfide surfaces in order to decrease the mobility of metals and metalloids over longer time scale. This will result in a lower cost and efforts of measures after mine closure. Results from the experiments will be presented.

  19. Chemically grown vertically aligned 1D ZnO nanorods with CdS coating for efficient quantum dot sensitized solar cells (QDSSC): a controlled synthesis route.

    Science.gov (United States)

    Mali, Sawanta S; Kim, Hyungjin; Patil, Pramod S; Hong, Chang Kook

    2013-12-28

    In the present article, vertically aligned ZnO nanorod arrays were synthesized by an aqueous chemical growth (ACG) route on a fluoride doped tin oxide (FTO) coated glass substrate. These nanorods were further sensitized with cadmium sulfide (CdS) quantum dots (QDs) by a successive ionic layer adsorption and reaction (SILAR) technique. The synthesized CdS coated ZnO nanorods were characterized for their structural and morphological properties with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). Finally, prepared CdS coated 1D ZnO photoelectrodes were tested for their photoelectrochemical performance. Our results show that the sample deposited after 40 SILAR cycles shows 5.61 mA cm(-2) short current density (JSC) with η = 1.61% power conversion efficiency.

  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. 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%)....

  2. Hydrogen sulfide in signaling pathways.

    Science.gov (United States)

    Olas, Beata

    2015-01-15

    For a long time hydrogen sulfide (H₂S) was considered a toxic compound, but recently H₂S (at low concentrations) has been found to play an important function in physiological processes. Hydrogen sulfide, like other well-known compounds - nitric oxide (NO) and carbon monoxide (CO) is a gaseous intracellular signal transducer. It regulates the cell cycle, apoptosis and the oxidative stress. Moreover, its functions include neuromodulation, regulation of cardiovascular system and inflammation. In this review, I focus on the metabolism of hydrogen sulfide (including enzymatic pathways of H₂S synthesis from l- and d-cysteine) and its signaling pathways in the cardiovascular system and the nervous system. I also describe how hydrogen sulfide may be used as therapeutic agent, i.e. in the cardiovascular diseases.

  3. Mechanochemical reduction of copper sulfide

    DEFF Research Database (Denmark)

    Balaz, P.; Takacs, L.; Jiang, Jianzhong

    2002-01-01

    The mechanochemical reduction of copper sulfide with iron was induced in a Fritsch P-6 planetary mill, using WC vial filled with argon and WC balls. Samples milled for specific intervals were analyzed by XRD and Mossbauer spectroscopy. Most of the reaction takes place during the first 10 min...... of milling and only FeS and Cu are found after 60 min. The main chemical process is accompanied by phase transformations of the sulfide phases as a result of milling. Djurleite partially transformed to chalcocite and a tetragonal copper sulfide phase before reduction. The cubic modification of FeS was formed...... first, transforming to hexagonal during the later stages of the process. The formation of off-stoichiometric phases and the release of some elemental sulfur by copper sulfide are also probable....

  4. Luminescence in Sulfides: A Rich History and a Bright Future

    Directory of Open Access Journals (Sweden)

    Philippe F. Smet

    2010-04-01

    Full Text Available Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs. The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles.

  5. Is cadmium hazardous to health. Cadmium - ein Gesundheitsrisiko

    Energy Technology Data Exchange (ETDEWEB)

    Zartner-Nyilas, G.; Valentin, H.; Schaller, K.H.; Schiele, R.

    1983-01-01

    This study entitled ''Is cadmium hazardous to health'' summarizes the current state of knowledge on and experience with cadmium. The authors have made efforts to take into account the more recent literature relating to cadmium. The data evaluated were, especially, biological, toxicological, and epidemiological ones. A principal object was to try to assess the importance of the presence of cadmium in the environment to man. The interest was focused on the uptake of heavy metals with food, danger thresholds for the cadmium exposure of the population, nature and extent of eventual damage to health including possible carcinogenous effects, and suggestions for further points of main emphasis in research. 3 figs., 12 tabs.

  6. Luminescent properties of fluorophosphate glasses with molecular cadmium selenide clusters

    Science.gov (United States)

    Kolobkova, E. V.; Kukushkin, D. S.; Nikonorov, N. V.; Sidorov, A. I.; Shakhverdov, T. A.

    2015-02-01

    It is experimentally shown that, prior to the formation of CdSe quantum dots in fluorophosphate glasses with cadmium and selenium ions in the process of synthesis, subnanosized molecular clusters (CdSe) n are formed, which exhibit luminescence in the visible spectral region upon UV excitation. Heat treatment of the glasses increases the size of molecular clusters and makes their optical properties closer to the optical properties of CdSe semiconductor quantum dots. An increase in the sample temperature from 20 to 250°C leads to reversible thermal quenching of the luminescence.

  7. Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production

    Science.gov (United States)

    Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

    2017-01-01

    Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h-1 g-1 and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1-xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes.

  8. Novel one pot stoichiometric synthesis of nickel sulfide nanomaterials as counter electrodes for QDSSCs

    Energy Technology Data Exchange (ETDEWEB)

    Mani, A. Daya; Deepa, Melepurath [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India); Xanthopoulos, N. [Ecole Polytechnique Federale de Lausanne (EPFL), CH-Lausanne (Switzerland); Subrahmanyam, Ch, E-mail: csubbu@iith.ac.in [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India)

    2014-11-14

    Solution combustion synthesis has been used for the first time to synthesize metal sulfide nanomaterials. Selective stoichiometric synthesis of nickel sulfide nanomaterials was achieved in a single step by using combustion synthesis under ambient conditions and the samples were tested as counter electrodes in a typical quantum dot sensitized solar cell (QDSSC). By varying the oxidant/fuel ratio, different stoichiometric nickel sulfide nanomaterials were obtained. Interestingly, a maximum of fourfold increase in efficiency (1.1%) was achieved with nickel sulfide counter electrode when compared to the Pt counter electrode (0.25%). This can be attributed to the less charge transfer resistance offered by nickel sulfide samples compared to Pt, which was confirmed by electrochemical impedance spectroscopy. Among different stoichiometric compositions of nickel sulfide, Ni{sub 3}S{sub 2} was found to exhibit the least charge transfer resistance and superior solar cell efficiency. The present study describes a novel selective stoichiometric synthetic approach and facile fabrication procedure for low cost counter electrode materials in QDSSCs. - Highlights: • Novel and facile phase selective synthesis of nickel sulfide nanomaterials. • A different sensitization approach of TiO{sub 2} with CdS. • A simple paint approach for working and counter electrode fabrication. • Fourfold increase of efficiency with Ni{sub 3}S{sub 2} compared to the conventional Pt.

  9. Cadmium exposure in the Swedish environment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This report gives a thorough description of cadmium in the Swedish environment. It comprises three parts: Cadmium in Sweden - environmental risks;, Cadmium in goods - contribution to environmental exposure;, and Cadmium in fertilizers, soil, crops and foods - the Swedish situation. Separate abstracts have been prepared for all three parts

  10. Cadmium carcinogenesis – some key points

    OpenAIRE

    2011-01-01

    The article presents briefly the main mechanisms of cadmium carcinogenesis and the most important sites of cancer (lung, breast, prostate, testes, kidney) induced by cadmium. In spite of some evidence showing carcinogenic potential of cadmium, further research is still required to elucidate the relative contributions of various molecular mechanisms involved in cadmium carcinogenesis

  11. Cadmium carcinogenesis – some key points

    Directory of Open Access Journals (Sweden)

    Loreta Strumylaite

    2011-09-01

    Full Text Available The article presents briefly the main mechanisms of cadmium carcinogenesis and the most important sites of cancer (lung, breast, prostate, testes, kidney induced by cadmium. In spite of some evidence showing carcinogenic potential of cadmium, further research is still required to elucidate the relative contributions of various molecular mechanisms involved in cadmium carcinogenesis

  12. Effects of Self-Assembled Monolayers on Solid-State CdS Quantum Dot Sensitized Solar Cells

    KAUST Repository

    Ardalan, Pendar

    2011-02-22

    Quantum dot sensitized solar cells (QDSSCs) are of interest for solar energy conversion because of their tunable band gap and promise of stable, low-cost performance. We have investigated the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state QDSSCs. CdS quantum dots ∼2 to ∼6 nm in diameter were grown on SAM-passivated planar or nanostructured TiO 2 surfaces by successive ionic layer adsorption and reaction (SILAR), and photovoltaic devices were fabricated with spiro-OMeTAD as the solid-state hole conductor. X-ray photoelectron spectroscopy, Auger electron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, water contact angle measurements, ellipsometry, and electrical measurements were employed to characterize the materials and the resulting device performance. The data indicate that the nature of the SAM tailgroup does not significantly affect the uptake of CdS quantum dots on TiO2 nor their optical properties, but the presence of the SAM does have a significant effect on the photovoltaic device performance. Interestingly, we observe up to ∼3 times higher power conversion efficiencies in devices with a SAM compared to those without the SAM. © 2011 American Chemical Society.

  13. Cadmium immobilization by hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Smičiklas Ivana D.

    2003-01-01

    Full Text Available The contamination of air, soil and water by cadmium is a great environmental problem. If cadmium occurs in nature in ionic form, soluble in water, it easily enters into the food chain. Hydroxyapatite (HAP, Ca-o(POAe(OH2 is a sparingly soluble salt and an excellent matrix for the removal of heavy metals from solutions. Considerable research attention has been paid to the bond between Cc/2+ ions and synthetic hydroxyapatite of known composition. The sorption mechanism is complex. The dominant process is ion exchange, but surface adsorption, surface complexation and coprecipitation can also contribute to the overall mechanism. The sorption capacity depends on the characteristics of hydroxyapatite itself and on the experimental conditions. Under optimum conditions a maximum capacity of 0.8 mol Cd2+/mol HAP can be achieved. HAP is a potential sorbent for the remediation of contaminated water and soil, for industrial waste treatment, and it is also referenced as a material that can be used as a barrier around waste depositories.

  14. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH, β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group. β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  15. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    PENG LingLing; ZHANG Xiu; MA Jie; ZHONG ZhenZhen; ZHANG Zhe; ZHANG Yan; WANG JianBo

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH.,β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group.β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  16. Nanostructured metal sulfides for energy storage.

    Science.gov (United States)

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-07

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

  17. 30 CFR 250.604 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.604 Section 250.604... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Workover Operations § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  18. 30 CFR 250.504 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.504 Section 250.504... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Completion Operations § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  19. 30 CFR 250.808 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.808 Section 250.808... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Safety Systems § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of...

  20. Modeling the band gap of CdS quantum well structures

    Science.gov (United States)

    Harris, R. A.; Terblans, J. J.

    2016-10-01

    Within the framework of the effective mass approximation, an excited electron is studied in a cadmium sulfide (CdS) quantum well with varying well widths. The envelope function approximation is employed involving a three parameter variational calculation wherein one of these parameters is the distance between the electron and the hole. The relative change in the electron's energy (relative to its energy when it is in the valence band; in the hole) is investigated as a function of the electron-hole distance. Results from numerical calculations are presented and the non-linear behavior of different sized CdS quantum wells are discussed. Comparisons between experimentally measured CdS band gap energies (as a function of well-width) and the simulation data are made. A good agreement between the current model and experimental data exists. Density functional theory (DFT) calculations are done on crystallites of extremely small sizes to compare the current model's bandgap energies to DFT-predicted bandgap values at these extremes.

  1. Cadmium effects on the thyroid gland.

    Science.gov (United States)

    Jancic, Snezana A; Stosic, Bojan Z

    2014-01-01

    Cadmium has been listed as one of the 126 priority pollutants and a category I carcinogen. Carcinogenic effects of cadmium on the lungs, testicles, and prostate are widely recognized, but there has been insufficient research on the effect of cadmium on the thyroid gland. Cadmium has the affinity to accumulate not only in the liver, kidneys, and pancreas but also in the thyroid gland. It has been established that cadmium blood concentration correlates positively with its accumulation in the thyroid gland. Women of fertile age have higher cadmium blood and urine concentrations than men. In spite of its redox inertia, cadmium brings about oxidative stress and damage to the tissue by indirect mechanisms. Mitochondria are considered to be the main intracellular targets for cadmium. Colloid cystic goiter, adenomatoid follicular hyperplasia with low-grade dysplasia and thyroglobulin hypo- and asecretion, and parafollicular cell diffuse and nodular hyperplasia and hypertrophy are often found in chronic cadmium toxicity.

  2. STUDY OF HYDROGEN SULFIDE REMOVAL FROM GROUNDWATER

    Directory of Open Access Journals (Sweden)

    T. Lupascu

    2013-06-01

    Full Text Available The process of the hydrogen sulfide removal from the underground water of the Hancesti town has been investigated. By oxygen bubbling through the water containing hydrogen sulfide, from the Hancesti well tube, sulfur is deposited in the porous structure of studied catalysts, which decreases their catalytic activity. Concomitantly, the process of adsorption / oxidation of hydrogen sulfide to sulfate take place. The kinetic research of the hydrogen sulfide removal from the Hancesti underground water, after its treatment by hydrogen peroxide, proves greater efficiency than in the case of modified carbonic adsorbents. As a result of used treatment, hydrogen sulfide is completely oxidized to sulfates

  3. Enrichment of cadmium in biomasses

    Energy Technology Data Exchange (ETDEWEB)

    Gwenner, C.; Wittig, H.; Glombitza, F.

    1986-01-01

    The uptake of cadmium ions from an aqueous solution by living, resting, and dead biomasses was investigated. The dependence of the uptaked amounts on pH-value of the medium, temperature and concentration of cadmium ions is demonstrated as well as the rate of uptake. Maximum realisable concentrations were 12 mg/g biomass in living cells and about 20 mg/g biomass in resting or dead cells, respectively.

  4. Interactions between N-acetyl-L-cysteine protected CdTe quantum dots and doxorubicin through spectroscopic method

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiupei, E-mail: xiupeiyang@163.com [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, Nanchong 637000 (China); College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637000 (China); Lin, Jia; Liao, Xiulin; Zong, Yingying; Gao, Huanhuan [College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637000 (China)

    2015-06-15

    Highlights: • CdTe quantum dots with the diameter of 3–5 nm were synthesized in aqueous solution. • The modified CdTe quantum dots showed well fluorescence properties. • The interaction between the CdTe quantum dots and doxorubicin (DR) was investigated. - Abstract: N-acetyl-L-cysteine protected cadmium telluride quantum dots with a diameter of 3–5 nm were synthesized in aqueous solution. The interaction between N-acetyl-L-cysteine/cadmium telluride quantum dots and doxorubicin was investigated by ultraviolet–visible absorption and fluorescence spectroscopy at physiological conditions (pH 7.2, 37 °C). The results indicate that electron transfer has occurred between N-acetyl-L-cysteine/cadmium telluride quantum dots and doxorubicin under light illumination. The quantum dots react readily with doxorubicin to form a N-acetyl-L-cysteine/cadmium telluride-quantum dots/doxorubicin complex via electrostatic attraction between the −NH{sub 3}{sup +} moiety of doxorubicin and the −COO{sup −} moiety of N-acetyl-L-cysteine/cadmium telluride quantum dots. The interaction of N-acetyl-L-cysteine/cadmium telluride-quantum dots/doxorubicin complex with bovine serum albumin was studied as well, showing that the complex might induce the conformation change of bovine serum due to changes in microenvironment of bovine serum.

  5. Zinc-induced protection against cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Early, J.L.; Schnell, R.C.

    1978-02-01

    Pretreatment of male rats with cadmium acetate potentiates the duration of hexobarbital hypnosis and inhibits the rate of hepatic microsomal drug metabolism. Pretreatment of rats with zinc acetate protects against these alterations in drug action elicited by cadmium.

  6. Metallothionein and bioaccumulation of cadmium in juvenile bluegills exposed to aqueous and sediment-associated cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Cope, W.G.

    1991-01-01

    The author evaluated metallothionein (MT), free (unbound) hepatic cadmium and whole body cadmium as indicators of cadmium exposure in juvenile bluegills Lepomis macrochirus in laboratory tests. Two types of cadmium exposure were tested; aqueous and sediment-associated. In the aqueous tests, fish were exposed to cadmium (0.0 to 32.3 [mu]g/L) in an intermittent-flow diluter. In the sediment-associated cadmium test, fish were exposed to resuspended river sidment containing 1.3 to 21.4 [mu]g Cd/g (dry weight) at a nominal total suspended solids concentration of 1,000 mg/L in revolving, circular glass exposure chambers. Total cadmium concentrations were measured in various bluegill liver fractions, whole bluegill, water, and resuspended sediment to assess the partitioning and bioaccumulation of cadmium after the tests. Mean concentrations of MT and free cadmium in bluegill livers and concentrations of cadmium in whole bluegills were positively correlated with aqueous cadmium concentration and were equally suitable as indicators of aqueous cadmium exposure. Sediment-associated cadmium was biologically available, but to a lesser extent than aqueous cadmium. Cadmium concentrations in whole bluegills exposed to resuspended river sediment were 1.5- to 3.5-fold the concentrations in bluegills in sediment-free controls. Free cadmium and MT concentrations in bluegill liver and whole-body cadmium concentrations in bluegills were positively correlated with the cadmium concentrations in filtered water, resuspended sediment, and bulk river sediment; however, whole-body cadmim concentrations were a more sensitive indicator of exposure to sediment-associated cadmium than either free cadmium or MT concentratons in liver.

  7. Hydrogen sulfide and translational medicine

    OpenAIRE

    Guo, Wei; Cheng, Ze-yu; Zhu, Yi-Zhun

    2013-01-01

    Hydrogen sulfide (H2S) along with carbon monoxide and nitric oxide is an important signaling molecule that has undergone large numbers of fundamental investigations. H2S is involved in various physiological activities associated with the regulation of homeostasis, vascular contractility, pro- and anti-inflammatory activities, as well as pro- and anti-apoptotic activities etc. However, the actions of H2S are influenced by its concentration, reaction time, and cell/disease types. Therefore, H2S...

  8. Redox Biochemistry of Hydrogen Sulfide*

    OpenAIRE

    Kabil, Omer; Banerjee, Ruma

    2010-01-01

    H2S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of γ-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H2S production in the vasculature. However, patients with inherited deficiency in γ-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxid...

  9. Bioavailability of cadmium from linseed and cocoa

    DEFF Research Database (Denmark)

    Hansen, Max; Sloth, Jens Jørgen; Rasmussen, Rie Romme

    In Denmark and EU the exposure of cadmium from food is at a level that is relatively close to the Tolerable Daily Intake (TDI). This report describes an investigation of the bioavailability of cadmium in selected food items known to contain high levels of cadmium. The purpose was to provide data ...... or crushed linseed nor the intake of cocoa and chocolate....

  10. Sulfide intrusion and detoxification in seagrasses ecosystems

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    Sulfide intrusion in seagrasses represents a global threat to seagrasses and thereby an important parameter in resilience of seagrass ecosystems. In contrast seegrasses colonize and grow in hostile sediments, where they are constantly exposed to invasion of toxic gaseous sulfide. Remarkably little...... strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis, tracing sulfur compounds combined with ecosystem parameters we found different spatial, intraspecific and interspecific strategies to cope with sulfidic sediments. 1...... not present in terrestrial plants at that level. Sulfide is not necessarily toxic but used as sulfur nutrition, presupposing healthy seagrass ecosystems that can support detoxification mechanisms. Presence or absence of those mechanisms determines susceptibility of seagrass ecosystems to sediment sulfide...

  11. Phosphonate self-assembled monolayers as organic linkers in solid-state quantum dot sensetized solar cells

    KAUST Repository

    Ardalan, Pendar

    2010-06-01

    We have employed X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, water contact angle (WCA) measurements, ellipsometry, and electrical measurements to study the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state quantum dot sensitized solar cells (QDSSCs). ∼2 to ∼6 nm size CdS quantum dots (QDs) were grown on the SAM-passivated TiO2 surfaces by successive ionic layer adsorption and reaction (SILAR). Our results show differences in the bonding of the CdS QDs at the TiO2 surfaces with a SAM linker. Moreover, our data indicate that presence of a SAM increases the CdS uptake on TiO2 as well as the performance of the resulting devices. Importantly, we observe ∼2 times higher power conversion efficiencies in the devices with a SAM compared to those that lack a SAM. © 2010 IEEE.

  12. Oral cadmium chloride intoxication in mice

    DEFF Research Database (Denmark)

    Andersen, O; Nielsen, J B; Svendsen, P

    1988-01-01

    Diethyldithiocarbamate (DDC) is known to alleviate acute toxicity due to injection of cadmium salts. However, when cadmium chloride was administered by the oral route, DDC enhanced rather than alleviated the acute toxicity; both oral and intraperitoneal (i.p.) administration of DDC had this effect....... Thus, orally administered DDC enhanced cadmium-induced duodenal and ileal tissue damage and inhibition of peristalsis, as indicated by an increased intestinal transit time. At low cadmium doses, the whole-body retention of cadmium was increased by oral DDC administration. Intraperitoneally administered...

  13. Synthetic Developments of Nontoxic Quantum Dots.

    Science.gov (United States)

    Das, Adita; Snee, Preston T

    2016-03-03

    Semiconductor nanocrystals, or quantum dots (QDs), are candidates for biological sensing, photovoltaics, and catalysis due to their unique photophysical properties. The most studied QDs are composed of heavy metals like cadmium and lead. However, this engenders concerns over heavy metal toxicity. To address this issue, numerous studies have explored the development of nontoxic (or more accurately less toxic) quantum dots. In this Review, we select three major classes of nontoxic quantum dots composed of carbon, silicon and Group I-III-VI elements and discuss the myriad of synthetic strategies and surface modification methods to synthesize quantum dots composed of these material systems.

  14. Arsenic-cadmium interaction in rats.

    Science.gov (United States)

    Díaz-Barriga, F; Llamas, E; Mejía, J J; Carrizales, L; Santoyo, M E; Vega-Vega, L; Yáñez, L

    1990-11-01

    Simultaneous exposure to cadmium and arsenic is highly probable in the urban area of San Luis Potosi, Mexico due to common localization of copper and zinc smelters. Therefore, in this work, rats were intraperitoneally exposed either to cadmium or arsenic alone, or simultaneously to both metals. The effects of these treatments on three different toxicological parameters were studied. Cadmium modified the LD50 of arsenic and conversely arsenic modified the LD50 for cadmium. At the histopathological level, arsenic appeared to protect against the cadmium effects, especially on testes. This protective effect seemed to be related to the glutathione levels found in this tissue: rats exposed to both arsenic and cadmium, presented glutathione values intermediate to those observed after exposure to either metal alone; arsenic had the highest value and cadmium the lowest. In liver, rats exposed to arsenic, cadmium or arsenic and cadmium, presented glutathione values below those in the saline group, with the lowest value corresponding to the arsenic and cadmium treatment. The results appear to support the proposed interaction between arsenic and cadmium and coexposure to both metals seems to alter certain effects produced by either metal alone.

  15. Insulin Expression in Rats Exposed to Cadmium

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objectives To investigate the effects of cadmium exposure on insulin expression in rats. Methods Eighteen adult SD assessed. The levels of cadmium and zinc in pancreas, blood and urine glucose, serum insulin and urine NAG (N-acyetyl-β-glucosaminidase) were determined. The gene expressions of metallothionein (MT) and insulin were also measured,and the oral glucose tolerance tests (OGTT) were carried out. Results The contents of cadmium in pancreas in cadmium-treated rats were higher than that in the control group, which was associated with slight increase of zinc in pancreas.not change significantly after cadmium administration, and the UNAG had no change in Cd-treated group. The gene expression the change of the expression of insulin, MT-Ⅰ and MT-Ⅱ genes. Cadmium can influence the biosynthesis of insulin, but does not induce the release of insulin. The dysfunction of pancreas occurs earlier than that of kidney after administration of cadmium.

  16. Photoluminescent Response of Palladium-Cadmium Sulfide and Palladium-Graded Cadmium Sulfoselenide Schottky Diodes to Molecular Hydrogen.

    Science.gov (United States)

    2014-09-26

    assistance - and helpful discussions. 8 Re ferences 1. Hollingsworth, R. E.; Sites, J. R. 3. Appi . Phys. 1982, 53, 5357 and references therein. 2. Hobson...W. S.; Ellis, A. B. J. Ap. Phys. 1983, 54, 5956 and references therein. 3. Mettler, K. Appi . Phys. 1977, 12, 75. 4. Stephens, R. B. Phys. Rev.. B...1984, 29, 3283. 5. Steele, M. C.; Maclver, B. A. Appi . Phys. Lett. 1976, 28, 687. 6. Yamamoto, N.; Tonomura, S.; Matsuoka-, T.; Tsubomura, H. Surf. Sci

  17. Hydrogen sulfide and vascular relaxation

    Institute of Scientific and Technical Information of China (English)

    SUN Yan; TANG Chao-shu; DU Jun-bao; JIN Hong-fang

    2011-01-01

    Objective To review the vasorelaxant effects of hydrogen sulfide (H2S) in arterial rings in the cardiovascular system under both physiological and pathophysiological conditions and the possible mechanisms involved.Data sources The data in this review were obtained from Medline and Pubmed sources from 1997 to 2011 using the search terms "hydrogen sulfide" and ""vascular relaxation".Study selection Articles describing the role of hydrogen sulfide in the regulation of vascular activity and its vasorelaxant effects were selected.Results H2S plays an important role in the regulation of cardiovascular tone.The vasomodulatory effects of H2S depend on factors including concentration,species and tissue type.The H2S donor,sodium hydrosulfide (NarS),causes vasorelaxation of rat isolated aortic rings in a dose-dependent manner.This effect was more pronounced than that observed in pulmonary arterial rings.The expression of KATP channel proteins and mRNA in the aortic rings was increased compared with pulmonary artery rings.H2S is involved in the pathogenesis of a variety of cardiovascular diseases.Downregulation of the endogenous H2S pathway is an important factor in the pathogenesis of cardiovascular diseases.The vasorelaxant effects of H2S have been shown to be mediated by activation of KATP channels in vascular smooth muscle cells and via the induction of acidification due to activation of the CI/HCO3 exchanger.It is speculated that the mechanisms underlying the vasoconstrictive function of H2S in the aortic rings involves decreased NO production and inhibition of cAMP accumulation.Conclusion H2S is an important endogenous gasotransmitter in the cardiovascular system and acts as a modulator of vascular tone in the homeostatic regulation of blood pressure.

  18. Medical Functions of Hydrogen Sulfide.

    Science.gov (United States)

    Olas, Beata

    2016-01-01

    Hydrogen sulfide (H(2)S) is a gasomediator synthesized from L- and D-cysteine in various tissues. It is involved in a number of physiological and pathological processes. H(2)S exhibits antiatherosclerotic, vasodilator, and proangiogenic properties, and protects the kidney and heart from damage following ischemia/reperfusion injury. H(2)S donors may be natural or synthetic, and may be used for the safe treatment of a wide range of diseases. This review article summarizes the current state of knowledge of the therapeutic function of H(2)S.

  19. Molybdenum sulfide/carbide catalysts

    Science.gov (United States)

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  20. Quantum Dots Microstructured Optical Fiber for X-Ray Detection

    Science.gov (United States)

    DeHaven, Stan; Williams, Phillip; Burke, Eric

    2015-01-01

    Microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide are presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dot application technique are discussed.

  1. Quantum dots microstructured optical fiber for x-ray detection

    Science.gov (United States)

    DeHaven, S. L.; Williams, P. A.; Burke, E. R.

    2016-02-01

    A novel concept for the detection of x-rays with microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide is presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dots application technique are discussed.

  2. Ammonia and hydrogen sulfide removal using biochar

    Science.gov (United States)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  3. FCC汽油噻吩类硫化物烷基化硫转移反应机理的量子化学%Quantum Chemistry Research in Alkylation Sulfur Transfer Reaction Mechanism of Thiophene Sulfide in FCC Gasoline

    Institute of Scientific and Technical Information of China (English)

    徐亚荣; 沈本贤; 徐新良; 朱庆才

    2011-01-01

    With the catalytic alkylation of methyl-thiophene and 2-methybutene-2 as the model reaction, the alkylation mechanism and the orientation effect of thiophenes in FCC gasoline were theoretically studied by ab initio quantum chemistry. LST/QST/CG was used to search the transition state to prove the feasibility and specific path of 2'-carbonium to 3'-carbornium by rearrangement. The results showed that the energy of 3 -carbonium was lower than that of 2'-carbonium, reaction active energy released by 2'-carbonium rearrangement to 3'-carbonium was only 19. 74 kj/mol, meaning that the rearrangement was a exothermic process. Alkylation reaction of 2-methyl-thiophene was typical electrophilic substitution reaction. The geometry structures of reactants, intermediates, transition states and products were optimized by searching for transient with LST/QST/CG. Energy of transition TS1 with R and IM as starting point was - 2. 072 X 106 kj/mol, with only virtual frequency of 132 cm-1. Energy of transition TS2 with IM and P as starting point was -2.071X106 kj/mol , with only virtual frequency of 128. 9 cm-1.%以各种甲基噻吩与2-甲基丁烯-2在催化剂作用下的烷基化反应为模型反应,对FCC汽油的噻吩类硫化物的定位效应和烷基化反应机理进行了从头算的量子化学研究.采用LST/QST/CG进行过渡态搜索,验证仲正碳离子进行重排转变为叔正碳离子的可行性和具体途径.结果表明,计算得到的叔正碳离子的能量低于仲正碳离子的,仲正碳离子重排为叔正碳离子是放热过程,该反应的能垒仅19.74 kJ/mol.2-甲基噻吩的烷基化反应是典型的亲电取代反应,对中间体IM及产物P进行结构优化,以分子复合物R和IM为起点进行LST/QST/CG过渡态搜索,所得过渡态TS1经优化后的几何构型的能量为-2.072×106 kJ/mol,在132 cm-1有唯一的虚频;以IM和P为起点进行LST/QST/CG过渡态搜索,所得过渡态TS2经优化后的能量为-2.071×106 k

  4. Modulation of cadmium bioaccumulation and enhancing cadmium tolerance in Pichia kudriavzevii by sodium chloride preincubation.

    Science.gov (United States)

    Ma, Ning; Li, Chunsheng; Zhang, Dandan; Yu, Jinzhi; Xu, Ying

    2016-07-01

    Application of growing microorganisms for cadmium removal is limited by the sensitivity of living cells to cadmium. The effects of sodium chloride (NaCl) preincubation on the cadmium bioaccumulation and tolerance of Pichia kudriavzevii and Saccharomyces cerevisiae were investigated in this study. NaCl preincubation significantly reduced the intracellular and cell-surface cadmium bioaccumulation of P. kudriavzevii at both 6 and 20 mg L(-1) cadmium, while no obvious effect was observed in S. cerevisiae except that the intracellular cadmium bioaccumulation at 20 mg L(-1) cadmium was reduced obviously by 20-60 g L(-1)  NaCl. For both yeasts, the improved contents of protein and proline after NaCl preincubation contributed to the cadmium tolerance. The thiol contents in P. kudriavzevii under cadmium stress were alleviated by NaCl preincubation, which might be due to the decrease of intracellular cadmium bioaccumulation. NaCl preincubation enhanced the contents of glycerol and trehalose in P. kudriavzevii under cadmium stress, while no acceleration was observed in S. cerevisiae. The results suggested that NaCl preincubation could be applied in cadmium removal by growing P. kudriavzevii to increase the cadmium tolerance of the yeast.

  5. Sulfide toxicity kinetics of a uasb reactor

    Directory of Open Access Journals (Sweden)

    D. R. Paula Jr.

    2009-12-01

    Full Text Available The effect of sulfide toxicity on kinetic parameters of anaerobic organic matter removal in a UASB (up-flow anaerobic sludge blanket reactor is presented. Two lab-scale UASB reactors (10.5 L were operated continuously during 12 months. The reactors were fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. One of the reactors also received increasing concentrations of sodium sulfide. For both reactors, the flow rate of 16 L.d-1 was held constant throughout the experiment, corresponding to a hydraulic retention time of 15.6 hours. The classic model for non-competitive sulfide inhibition was applied to the experimental data for determining the overall kinetic parameter of specific substrate utilization (q and the sulfide inhibition coefficient (Ki. The application of the kinetic parameters determined allows prediction of methanogenesis inhibition and thus the adoption of operating parameters to minimize sulfide toxicity in UASB reactors.

  6. Bioaccumulation of cadmium by growing Zygosaccharomyces rouxii and Saccharomyces cerevisiae.

    Science.gov (United States)

    Li, Chunsheng; Jiang, Wei; Ma, Ning; Zhu, Yinglian; Dong, Xiaoyan; Wang, Dongfeng; Meng, Xianghong; Xu, Ying

    2014-03-01

    Bioaccumulation via growing cells is a potential technique for heavy metal removal from food materials. The cadmium bioaccumulation characteristics by growing Zygosaccharomyces rouxii and Saccharomyces cerevisiae were investigated. Z. rouxii displayed powerful cadmium removal ability at low cadmium concentrations, which mainly depended on the intracellular cadmium bioaccumulation. The percentage of intracellular cadmium bioaccumulation of both yeasts obviously decreased with the increase of initial biomass and cadmium concentrations. Low pH and elevated concentrations of zinc and copper significantly decreased the intracellular cadmium bioaccumulation of both yeasts but improved the cadmium tolerance and the cell-surface cadmium bioaccumulation of Z. rouxii. Cadmium removal of Z. rouxii was improved by zinc and copper conditionally. Z. rouxii that possessed more powerful cadmium tolerance and removal ability at low pH and high concentration of competing ions can be developed into a potential cadmium removal agent using in complex food environment in future.

  7. Enhancement of Charge Transfer and Quenching of Photoluminescence of Capped CdS Quantum Dots

    Science.gov (United States)

    Mehata, Mohan Singh

    2015-07-01

    Quantum dots (Q-dots) of cadmium sulfide (CdS) with three different capping ligands, 1-butanethiol (BT), 2-mercaptoethanol (ME) and benzyl mercaptan (BM) have been investigated. An external electric field of variable strength of 0.2-1.0 MV cm-1 was applied to the sample of capped CdS Q-dots doped in a poly(methyl methacrylate) (PMMA) films. Field-induced changes in optical absorption of capped CdS Q-dots were observed in terms of purely the second-derivative of the absorption spectrum (the Stark shift), indicating an enhancement in electric dipole moment following transition to the first exciton state. The enhancement depends on the shape and size of the Q-dots prepared using different capping ligands. Field induced-change in photoluminescence (PL) reveals similar changes, an enhancement in charge-transfer (CT) character in exciton state. PL of capped CdS Q-dots is significantly quenched in presence of external electric field. The strong field-induced quenching occurs as a result of the increased charge separation resulting exciton dissociation. Thus, understanding the CT character and field-induced PL quenching of CdS Q-dots is important for photovoltaic, LEDs and biological applications.

  8. Investigation of novel quantum dots/proteins/cellulose bioconjugate using NSOM and photoluminescence

    Science.gov (United States)

    Zhang, Peng; Ding, Shi-You; Xu, Qi; Smith, Steve; Rumbles, Garry; Himmel, Michael E.

    2004-10-01

    We investigated the engineered bioconjugate of cadmium selenide core/zinc sulfide shell, (CdSe)ZnS, quantum dots (QDs) with genetically modified proteins using near-field scanning optical microscopy (NSOM). A genetically engineered protein polymer was expressed and purified from E. coli. The protein polymer was allowed to self-assemble to the bacterial microcrystalline cellulose surface through the cellulosic binding domain. QDs were then conjugated to the protein/cellulose assembly through interaction with the 6x-histidine tag on the protein. The transmitted near-field optical signals are collected and detected by both a PMT (near-field scanning optical microscopy, NSOM) and a spectrometer (near-field scanning optical spectroscopy, NSOS). Results from the sample containing the QDs/protein/cellulose assemblies suggest that QDs were arrayed along the cellulose surface. The near-field spectroscopic study also showed that the slight change of spectroscopic properties of the QDs upon bioconjugation, indicating the strong interaction between the constructed protein and QDs.

  9. 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.

  10. Sulfide oxidation as a process for the formation of copper-rich magmatic sulfides

    Science.gov (United States)

    Wohlgemuth-Ueberwasser, Cora C.; Fonseca, Raúl O. C.; Ballhaus, Chris; Berndt, Jasper

    2013-01-01

    Typical magmatic sulfides are dominated by pyrrhotite and pentlandite with minor chalcopyrite, and the bulk atomic Cu/Fe ratio of these sulfides is typically less than unity. However, there are rare magmatic sulfide occurrences that are dominated by Cu-rich sulfides (e.g., bornite, digenite, and chalcopyrite, sometimes coexisting with metallic Cu) with atomic Cu/Fe as high as 5. Typically, these types of sulfide assemblages occur in the upper parts of moderately to highly fractionated layered mafic-ultramafic intrusions, a well-known example being the Pd/Au reef in the Upper Middle Zone of the Skaergaard intrusion. Processes proposed to explain why these sulfides are so unusually rich in Cu include fractional crystallization of Fe/(Ni) monosulfide and infiltration of postmagmatic Cu-rich fluids. In this contribution, we explore and experimentally evaluate a third possibility: that Cu-rich magmatic sulfides may be the result of magmatic oxidation. FeS-dominated Ni/Cu-bearing sulfides were equilibrated at variable oxygen fugacities in both open and closed system. Our results show that the Cu/Fe ratio of the sulfide melt increases as a function of oxygen fugacity due to the preferential conversion of FeS into FeO and FeO1.5, and the resistance of Cu2S to being converted into an oxide component even at oxygen fugacities characteristic of the sulfide/sulfate transition (above FMQ + 1). This phenomenon will lead to an increase in the metal/S ratio of a sulfide liquid and will also depress its liquidus temperature. As such, any modeling of the sulfide liquid line of descent in magmatic sulfide complexes needs to address this issue.

  11. Tolerance to cadmium and cadmium-binding ligands in Great Salt Lake brine shrimp (Artemia salina)

    Energy Technology Data Exchange (ETDEWEB)

    Jayasekara, S.; Drown, D.B.; Sharma, R.P.

    1986-02-01

    Information on the accumulation of cadmium in cytosolic proteins of Great Lake brine shrimp (Artemia salina) was obtained from animals collected directly from the lake and also from animal hatched and maintained in three sublethal concentrations of cadmium (0.5, 2.0, 5.0 ppm) in saltwater aquaria. Brine shrimp growth under these conditions was monitored by measuring body lengths during a 7-day exposure period. Heat-stable, cadmium-binding ligands were isolated and identified by Sephadex G-75 chromatography and atomic absorption spectrophotometry. Cadmium was found to be equally distributed between high and low molecular weight proteins in animals collected from the lake and the 0.5 ppm cadmium group. There was also a slight growth stimulation noted in the 0.5-pm group. Higher cadmium incorporation was noted in low molecular weight fractions with increasing cadmium concentration in the exposure media. Low molecular weight fractions were also found to have high uv absorption characteristics at 250 nm and low absorption at 280 nm. Molecular weight of the cadmium-binding ligands was found to be 11,000 as estimated by the gel filtration method. De novo synthesis of this protein was increased as a function of cadmium concentration in the media. However, slow accumulation of cadmium in other protein fractions was also noticed in higher cadmium exposure groups, suggesting the existence of possible tolerance mechanisms in brine shrimp exposed to suspected acute cadmium concentrations.

  12. Thermal Decomposition Based Synthesis of Ag-In-S/ZnS Quantum Dots and Their Chlorotoxin-Modified Micelles for Brain Tumor Cell Targeting.

    Science.gov (United States)

    Chen, Siqi; Ahmadiantehrani, Mojtaba; Publicover, Nelson G; Hunter, Kenneth W; Zhu, Xiaoshan

    Cadmium-free silver-indium-sulfide (Ag-In-S or AIS) chalcopyrite quantum dots (QDs) as well as their core-shell structures (AIS/ZnS QDs) are being paid significant attention in biomedical applications because of their low toxicity and excellent optical properties. Here we report a simple and safe synthetic system to prepare high quality AIS and AIS/ZnS QDs using thermal decomposition. The synthetic system simply involves heating a mixture of silver acetate, indium acetate, and oleic acid in dodecanethiol at 170 °C to produce AIS QDs with a 13% quantum yield (QY). After ZnS shell growth, the produced AIS/ZnS QDs achieve a 41% QY. To facilitate phase transfer and bioconjugation of AIS/ZnS QDs for cellular imaging, these QDs were loaded into the core of PLGA-PEG (5k:5k) based micelles to form AIS/ZnS QD-micelles. Cellular imaging studies showed that chlorotoxin-conjugated QD-micelles can be specifically internalized into U-87 brain tumor cells. This work discloses that the scalable synthesis of AIS/ZnS QDs and the facile surface/interface chemistry for phase transfer and bioconjugation of these QDs may open an avenue for the produced QD-micelles to be applied to the detection of endogenous targets expressed on brain tumor cells, or more broadly to cell- or tissue-based diagnosis and therapy.

  13. Study on characteristics of CdS quantum dot-sensitized solar cells prepared by successive ionic layer adsorption and reaction with different adsorption times

    Science.gov (United States)

    Jeong, Myeong-Soo; Son, Min-Kyu; Kim, Soo-Kyoung; Park, Songyi; Prabakar, Kandasamy; Kim, Hee-Je

    2014-05-01

    Cadmium sulfide (CdS) quantum dots (QDs) were adsorbed on a titanium dioxide (TiO2) nanoporous film by successive ionic layer adsorption and reaction (SILAR) method with different adsorption times to study the influences of different SILAR adsorption times on CdS quantum dot-sensitized solar cells (QDSCs). The optical properties of CdS sensitized TiO2 films were studied by scanning electron microscopy and UV-Vis absorbance spectroscopy. The particle size of the CdS QDs was approximated using the effective mass approximation theory from the absorbance spectra. The photovoltaic characteristics of the CdS QDSCs were analyzed by I- V characteristics and electrochemical impedance spectroscopy under air mass 1.5 illumination. As a result, the particle size of the CdS QDs became larger and light harvesting was enhanced with increasing SILAR adsorption time. The maximum photovoltaic conversion efficiency of the CdS QDSCs (1.86%) was obtained at the SILAR adsorption time of 30 min with the highest short circuit current density and lowest charge transfer resistance.

  14. Zone refining of cadmium and related characterization

    Indian Academy of Sciences (India)

    N R Munirathnam; D S Prasad; Ch Sudheer; J V Rao; T L Prakash

    2005-06-01

    We present the zone refining results of cadmium using horizontal resistive zone refiner under constant flow of moisture free hydrogen gas. The boron impurity in cadmium can be avoided using quartz (GE 214 grade) boat in lieu of high pure graphite boat. The analytical results using inductively coupled plasma optical emission spectrometry (ICPOES) show that majority of the impurities are less than the detection limits. Comparatively, zinc is the most difficult impurity element to remove in cadmium matrix by zone refining.

  15. 21 CFR 177.2490 - Polyphenylene sulfide resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyphenylene sulfide resins. 177.2490 Section 177... Components of Articles Intended for Repeated Use § 177.2490 Polyphenylene sulfide resins. Polyphenylene sulfide resins (poly(1,4-phenylene sulfide) resins) may be safely used as coatings or components...

  16. The Epigenetic Effects of Prenatal Cadmium Exposure.

    Science.gov (United States)

    Vilahur, Nadia; Vahter, Marie; Broberg, Karin

    2015-06-01

    Prenatal exposure to the highly toxic and common pollutant cadmium has been associated with adverse effects on child health and development. However, the underlying biological mechanisms of cadmium toxicity remain partially unsolved. Epigenetic disruption due to early cadmium exposure has gained attention as a plausible mode of action, since epigenetic signatures respond to environmental stimuli and the fetus undergoes drastic epigenomic rearrangements during embryogenesis. In the current review, we provide a critical examination of the literature addressing prenatal cadmium exposure and epigenetic effects in human, animal, and in vitro studies. We conducted a PubMed search and obtained eight recent studies addressing this topic, focusing almost exclusively on DNA methylation. These studies provide evidence that cadmium alters epigenetic signatures in the DNA of the placenta and of the newborns, and some studies indicated marked sexual differences for cadmium-related DNA methylation changes. Associations between early cadmium exposure and DNA methylation might reflect interference with de novo DNA methyltransferases. More studies, especially those including environmentally relevant doses, are needed to confirm the toxicoepigenomic effects of prenatal cadmium exposure and how that relates to the observed health effects of cadmium in childhood and later life.

  17. Adequate hydrogen sulfide, healthy circulation

    Institute of Scientific and Technical Information of China (English)

    DU Jun-bao; CHEN Stella; JIN Hong-fang; TANG Chao-shu

    2011-01-01

    Previously,hydrogen sulfide (H2S) was considered to be a toxic gas.However,recently it was discovered that it could be produced in mammals and even in plants,throughtheproductionandmetabolismof sulfur-containing amino acids.In mammals,H2S is mainly catalyzed by cystathionine-γ-lyase (CSE),cystathionin-β-lyase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) with the substrate of L-cysteine.Endogenous H2S exerts many important physiological and pathophysiological functions,including hypotensive action,vasorelaxation,myocardial dilation,inhibition of smooth muscle cell proliferation,and antioxidatve actions.Importantly,it plays a very important role in the pathogenesis of systemic hypertension,pulmonary hypertension,atherosclerosis,myocardialinjury,angiogenesis,hyperhomocysteinemi aandshock.Therefore,H2S is now being considered to be a novel gasotransmitter after nitric oxide and carbon monoxide in the regulation of circulatory system.

  18. Redox biochemistry of hydrogen sulfide.

    Science.gov (United States)

    Kabil, Omer; Banerjee, Ruma

    2010-07-16

    H(2)S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of gamma-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H(2)S production in the vasculature. However, patients with inherited deficiency in gamma-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxidative phosphorylation while also exposing cytochrome c oxidase to this metabolic poison. This report focuses on the biochemistry of H(2)S biogenesis and clearance, on the molecular mechanisms of its action, and on its varied biological effects.

  19. Uptake, retention and internalization of quantum dots in Daphnia is influenced by particle surface functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Feswick, A., E-mail: afeswick@yahoo.ca [Center for Environmental and Human Toxicology, University of Florida, PO Box 110885, Gainesville, FL 32611 (United States); Canadian Rivers Institute, University of New Brunswick, PO Box 5050, Saint John NB, CA (United States); Griffitt, R.J., E-mail: joe.griffitt@usm.edu [Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564 (United States); Siebein, K., E-mail: kerry.siebein@nist.gov [Major Analytical Instrumentation Center, University of Florida, PO Box 116400, Gainesville, FL 32611 (United States); Barber, D.S., E-mail: barberd@vetmed.ufl.edu [Center for Environmental and Human Toxicology, University of Florida, PO Box 110885, Gainesville, FL 32611 (United States)

    2013-04-15

    Highlights: ► Daphnia underwent a waterborne exposure of PEG, NH{sub 2} and COOH functionalized quantum dot nanoparticles. ► There was preferential retention of COOH nanoparticles. ► TEM demonstrated that NH{sub 2} and COOH nanoparticles were internalized in cells adjacent to the GI tract. ► This cellular internalization was confirmed using energy dispersive spectroscopy. -- Abstract: Nanomaterials are a diverse group of compounds whose inevitable release into the environment warrants study of the fundamental processes that govern the ingestion, uptake and accumulation in aquatic organisms. Nanomaterials have the ability to transfer to higher trophic levels in aquatic ecosystems, and recent evidence suggests that the surface chemistry of both the nanoparticle and biological membrane can influence uptake kinetics. Therefore, our study investigates the effect of surface functionalization on uptake, internalization and depuration in Daphnia spp. Uncharged (polyethylene glycol; PEG), positively charged (amino-terminated: NH{sub 2}) and negatively charged (carboxyl-modified; COOH) cadmium selenide/zinc sulfide quantum dots were used to monitor ingestion, uptake and depuration of nanometals in Daphnia magna and Ceriodaphnia dubia over 24 h of exposure. These studies demonstrated that particles with higher negative charge (COOH quantum dots) were taken up to a greater extent by Daphnia (259.17 ± 17.70 RFU/20 Daphnia) than either the NH{sub 2} (150.01 ± 18.91) or PEG quantum dots (95.17 ± 9.78), however this is likely related to the functional groups attached to the nanoparticles as there were no real differences in zeta potential. Whole body fluorescence associates well with fluorescent microscopic images obtained at the 24 h timepoint. Confocal and electron microscopic analysis clearly demonstrated that all three types of quantum dots could cross the intestinal epithelial barrier and be translocated to other cells. Upon cessation of exposure, elimination of

  20. Microbial control of hydrogen sulfide production

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J. [Univ. of Oklahoma, Tulsa, OK (United States)] [and others

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  1. Removal of methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide from contaminated air by Thiobacillus thioparus TK-m.

    OpenAIRE

    Kanagawa, T; Mikami, E.

    1989-01-01

    Methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide were efficiently removed from contaminated air by Thiobacillus thioparus TK-m and oxidized to sulfate stoichiometrically. More than 99.99% of dimethyl sulfide was removed when the load was less than 4.0 g of dimethyl sulfide per g (dry cell weight) per day.

  2. Hydrogen Sulfide Induces Oxidative Damage to RNA and DNA in a Sulfide-Tolerant Marine Invertebrate

    OpenAIRE

    Joyner-Matos, Joanna; Predmore, Benjamin L.; Stein, Jenny R.; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes ...

  3. Hydrogen sulfide at high pressure: Change in stoichiometry

    Science.gov (United States)

    Goncharov, Alexander F.; Lobanov, Sergey S.; Kruglov, Ivan; Zhao, Xiao-Miao; Chen, Xiao-Jia; Oganov, Artem R.; Konôpková, Zuzana; Prakapenka, Vitali B.

    2016-05-01

    Hydrogen sulfide (H2S ) was studied by x-ray synchrotron diffraction and Raman spectroscopy up to 150 GPa at 180-295 K and by quantum-mechanical variable-composition evolutionary simulations. The experiments show that H2S becomes unstable with respect to formation of compounds with different structure and composition, including Cccm and a body-centered cubic like (R 3 m or I m -3 m ) H3S , the latter one predicted previously to show a record-high superconducting transition temperature, a Tc of 203 K. These experiments provide experimental ground for understanding of this record-high Tc. The experimental results are supported by theoretical structure searches that suggest the stability of H3S , H4S3 , H5S8 , H3S5 , and H S2 compounds that have not been reported previously at elevated pressures.

  4. Photoluminescence study of copper-doped cadmium-telluride and related stability issues for cadmium-sulfide/cadmium-telluride solar-cell devices

    Science.gov (United States)

    Grecu, Dan S.

    Lifetime predictions for CdTe photovoltaic modules represent a complex problem, partly due to the fact that a fundamental understanding of the CdTe material properties and device operation is far from being complete. One of the stability issues actively investigated is the use of Cu for the formation of a back contact. Cu is one of the few good p-dopants for CdTe, which, by forming a p+ layer at the surface of the CdTe, relaxes the requirement for a high work function metal at the back contact. On the other hand, it is known that Cu is a fast diffuser in CdTe and it was suggested that Cu migration within the device could lead to some of the observed degradation effects. in this work, we explore Cu states and migration effects in CdTe and CdS/CdTe devices using photoluminescence (PL) as the main investigative method. We confirm the assignment of several Cu-related PL transitions observed in the CdTe spectrum, namely, a bound exciton transition (X, CUCd) at 1.59eV and a donor-acceptor pair (DAP) (D, CuCd) at 1.45eV. In addition, we observe and characterize new effects related to Cu diffusion in CdTe: (a) the quenching of a DAP, Cd-vacancy related band, at 1.55eV, and (b) the formation of a new strong lattice-coupled transition at 1.555eV. These effects, we suggest, are consistent with Cu atoms occupying substitutional positions on the Cd sublattice and/or forming Frenkel pairs of the type CUi-VCd- with Cd vacancies. Similar spectral characteristics are observed for the low-S-content CdS-CdTe alloy existent in the vicinity of the junction in solar-cell devices. Using Cu-induced changes in the PL spectrum, we propose that Cu diffuses rapidly through an interstitial mechanism, as a positively charged ion, throughout the CdTe and possibly the CdS layer during the back-contact fabrication procedure. Applied electrical fields can reverse the direction of Cu migration leading to device performance degradation. In addition, it was found that Cu-doped CdTe samples exhibit a substantial, thermally restorable "aging" behavior. PL results indicate that Cu acceptor states decay simultaneously with the formation of nonradiative recombination centers.

  5. Detection of Reactive Oxygen Species Induced by Cadmium Tellurium Quantum Dots%碲化镉量子点诱导氧自由基产生的检测

    Institute of Scientific and Technical Information of China (English)

    刘娜; 赵淑锐; 林彤; 冯爽; 牟颖; 韩四海; 黄沛力; 孙志伟

    2012-01-01

    With the extensive application of quantum dots (QDs) in biomarker and bioimaging, the amount of human exposure to QDs increases, so the exploration of the mechanism of their biological toxicity is of significant concern. The generation of ROS (reactive oxygen species) induced by QDs is accepted to act as a mechanism to produce toxicity. To investigate the relationship between the toxicity of QDs and the production of ROS, cadmhim-telhiride QDs (CdTe QDs and CdTe/ZnS QDs) were selected, and the type and intensity of ROS were detected using electron paramagnetic resonance (EPR) when adding various concentrations of CdTe QDs or CdTe/ZnS QDs in the cell-free system. The promotive effect of CdTe QDs or CdTe/ZnS QDs on the production of superoxide anion ( · O2- ) and hydroxyl free radicals ( · OH) was studied by EPR, ultraviolet and fluorescence spectrophotometer. Results showed that CdTe QDs could induce the production of · O2-,. The generation of · OH and ·O2- could be obviously promoted by CdTe QDsand CdTe/ZnS QDs. The intensity of ·OH (or ·O2- ) and the dose of QDs showed a clear dose-effect relationship. It was indicated that QDs could induce and promote the production of ROS. The inducing and promoting effect was dependent on the structure of QDs.%随着量子点(quantum dots,QDs)在生物标记和医学影像等领域的应用日益广泛,其环境暴露量逐渐增加,深入探讨QDs的毒性机制具有重要意义.QDs通过产生活性氧(ROS)诱发毒性效应是目前普遍接受的毒作用模式.为了探讨量子点的毒性与所诱发的ROS的种类和数量的关系,选用碲化镉量子点(CdTe QDs和CdTe/ZnS QDs),利用电子顺磁共振技术(EPR)分别测定了CdTe QDs和CdTe/ZnS QDs在无细胞体系中诱导ROS产生的种类和强度;利用EPR法、紫外可见分光光度法和荧光分光光度法分别测定了4、20和l 00 nmol· mL-1的CdTe QDs和CdTe/ZnS QDs对超氧阴离子(·O-2)和羟基自由基(·OH)产生的促进作

  6. Nitrate-reducing, sulfide-oxidizing bacteria as microbial oxidants for rapid biological sulfide removal.

    Science.gov (United States)

    De Gusseme, Bart; De Schryver, Peter; De Cooman, Michaël; Verbeken, Kim; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2009-01-01

    The emission of hydrogen sulfide into the atmosphere of sewer systems induces the biological production of sulfuric acid, causing severe concrete corrosion. As a possible preventive solution, a microbial consortium of nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) was enriched in a continuously stirred tank reactor in order to develop a biological technique for the removal of dissolved sulfide. The consortium, dominated by Arcobacter sp., was capable of removing 99% of sulfide. Stable isotope fractioning of the sulfide indicated that the oxidation was a biological process. The capacity of the NR-SOB consortium for rapid removal of sulfide was demonstrated by using it as an inoculum in synthetic and real sewage. Removal rates up to 52 mg sulfide-S g VSS(-1) h(-1) were achieved, to our knowledge the highest removal rate reported so far for freshwater species in the absence of molecular oxygen. Further long-term incubation experiments revealed the capacity of the bacteria to oxidize sulfide without the presence of nitrate, suggesting that an oxidized redox reserve is present in the culture.

  7. Improvement of cadmium phytoremediation after soil inoculation with a cadmium-resistant Micrococcus sp.

    Science.gov (United States)

    Sangthong, Chirawee; Setkit, Kunchaya; Prapagdee, Benjaphorn

    2016-01-01

    Cadmium-resistant Micrococcus sp. TISTR2221, a plant growth-promoting bacterium, has stimulatory effects on the root lengths of Zea mays L. seedlings under toxic cadmium conditions compared to uninoculated seedlings. The performance of Micrococcus sp. TISTR2221 on promoting growth and cadmium accumulation in Z. mays L. was investigated in a pot experiment. The results indicated that Micrococcus sp. TISTR2221significantly promoted the root length, shoot length, and dry biomass of Z. mays L. transplanted in both uncontaminated and cadmium-contaminated soils. Micrococcus sp. TISTR2221 significantly increased cadmium accumulation in the roots and shoots of Z. mays L. compared to uninoculated plants. At the beginning of the planting period, cadmium accumulated mainly in the shoots. With a prolonged duration of cultivation, cadmium content increased in the roots. As expected, little cadmium was found in maize grains. Soil cadmium was significantly reduced with time, and the highest percentage of cadmium removal was found in the bacterial-inoculated Z. mays L. after transplantation for 6 weeks. We conclude that Micrococcus sp. TISTR2221 is a potent bioaugmenting agent, facilitating cadmium phytoextraction in Z. mays L.

  8. Hydrogen sulfide in hemostasis: friend or foe?

    Science.gov (United States)

    Olas, Beata

    2014-06-25

    Hydrogen sulfide (H2S) is a well known toxic gas that is synthesized from the amino acids: cysteine (Cys) and homocysteine (Hcy) by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and mercaptopyruvate sulfurtransferase (3-MST). Hydrogen sulfide, like carbon monoxide (CO) or nitric oxide (NO) is a signaling molecule in different biological systems, including the cardiovascular system. Moreover, hydrogen sulfide plays a role in the pathogenesis of various cardiovascular diseases. It modulates different elements of hemostasis (activation of blood platelet, and coagulation process) as well as proliferation and apoptosis of vascular smooth muscle cells. However, the biological role and the therapeutic potential of H2S is not clear. This review summarizes the different functions of hydrogen sulfide in hemostasis.

  9. [Fatal outcome of an hydrogen sulfide poisoning].

    Science.gov (United States)

    Querellou, E; Jaffrelot, M; Savary, D; Savry, C; Perfus, J-P

    2005-10-01

    We report a case of fatal outcome poisoning by massive exposure to hydrogen sulfide of a sewer worker. This rare event was associated with a moderate intoxication of two members of the rescue team. The death was due to asystole and massive lung oedema. Autopsy analysis showed diffuse necrotic lesions in lungs. Hydrogen sulfide is a direct and systemic poison, produced by organic matter decomposition. The direct toxicity mechanism is still unclear. The systemic toxicity is due to an acute toxicity by oxygen depletion at cellular level. It is highly diffusable and potentially very dangerous. At low concentration, rotten egg smell must trigger hydrogen sulfide suspicion since at higher concentration it is undetectable, making intoxication possible. In case of acute intoxication, there is an almost instantaneous cardiovascular failure and a rapid death. Hydrogen sulfide exposure requires prevention measures and more specifically the use of respiratory equipment for members of the rescue team.

  10. Atomic scale investigations on Cd{sub x}Zn{sub 1−x}Se quantum dots: Correlation between the composition and emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Benallali, H., E-mail: hammouda.benallali@im2np.fr; Hoummada, K.; Mangelinck, D. [Aix-Marseille Université, IM2NP-CNRS, Case 142, 13397 Marseille Cedex 20 (France); Cremel, T.; André, R.; Tatarenko, S.; Kheng, K. [University of Grenoble Alpes, F-38000 Grenoble (France); CEA, INAC, F-38054 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France)

    2014-08-04

    Atom probe tomography and photoluminescence spectroscopy have been used to study Cd{sub x}Zn{sub 1−x}Se quantum dots embedded in a ZnSe layer grown on a (001) GaAs substrate. Atom probe tomography analyses show significant cadmium incorporation in the center of the dots surrounded by poor cadmium region. These measurements illustrate that the maximum cadmium concentration in the quantum dots is significantly higher than the concentration estimated by transmission electron microscopy. The composition and size of quantum dots obtained by atom probe tomography have been used to calculate the transition energies including excitonic and strain effects.

  11. Concurrent reduction and distillation: an improved technique for the recovery and chemical refinement of the isotopes of cadmium and zinc

    Energy Technology Data Exchange (ETDEWEB)

    Caudill, H.H.; McBride, L.E.; McDaniel, E.W.

    1982-01-01

    The Electromagnetic Isotope Separations Program of the Oak Ridge National Laboratory has been involved in the separation, chemical recovery, and refinement of the stable isotopes of cadmium and zinc since 1946. Traditionally, the chemical refinement procedures for these elements consisted of ion exchange separations using anion exchange resins followed by pH-controlled hydrogen sulfide precipitations. The procedures were quite time-consuming and made it difficult to remove trace quantities of sulfur which interferes in subsequent attempts to prepare rolled metal foils. As demands for /sup 113/Cd and /sup 68/Zn (a precursor for the production of the radiopharmaceutical /sup 67/Ga) increased, it became evident that a quicker, more efficient refinement procedure was needed. Details of an improved method, which employs concurrent hydrogen reduction and distillation in the recovery and refinement of isotopically enriched zinc, are described. Modifications of the procedure suitable for the refinement of cadmium isotopes are also described. 3 figures, 1 table.

  12. Mechanism of mechanical activation for sulfide ores

    Institute of Scientific and Technical Information of China (English)

    HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun

    2007-01-01

    Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.

  13. Electrodialytic Removal of Cadmium from Straw Ash

    DEFF Research Database (Denmark)

    Hansen, Henrik; Ottosen, Lisbeth M.; Villumsen, Arne;

    1999-01-01

    A problem with flyash from straw and wood combustion is the high level of heavy metals, especially cadmium. Two electrodialytic remediation experiments were carried out on cadmium polluted flyash from straw combustion. The flyash could be cleaned to 1/3 of its initial level after 24 days...

  14. Cadmium and children : Exposure and health effects

    NARCIS (Netherlands)

    Schoeters, G.; Hond, E. Den; Zuurbier, M.; Naginiene, R.; Hazel, P.J. van den; Stilianakis, N.; Ronchetti, R.; Koppe, J.G.

    2006-01-01

    Cadmium exposure and accumulation in the body start at young age. Exposure routes in children are mainly via food, environmental tobacco smoke and house dust. Excretion from the body is limited. Cadmium accumulation in the kidney is responsible for effects such as nephrotoxicity and osteoporosis whi

  15. Cadmium and children: exposure and health effects.

    Science.gov (United States)

    Schoeters, Greet; Den Hond, Elly; Zuurbier, Moniek; Naginiene, Rima; van den Hazel, Peter; Stilianakis, Nikolaos; Ronchetti, Roberto; Koppe, Janna G

    2006-10-01

    Cadmium exposure and accumulation in the body start at young age. Exposure routes in children are mainly via food, environmental tobacco smoke and house dust. Excretion from the body is limited. Cadmium accumulation in the kidney is responsible for effects such as nephrotoxicity and osteoporosis which are observed at adult age. Cadmium exposure through inhalation is also associated with lung cancer in adulthood. Although transfer to the neonate through the placenta and through breast milk is limited, teratogenic and developmental effects were observed in experimental animals. The database on human studies involving children is limited, yet effects on motoric and perceptual behaviour in children have been associated with elevated in utero cadmium exposure. In school age children urinary cadmium levels were associated with immune suppressive effects. More studies are needed to confirm these results. Experimental data in vitro and in animals refer to effects of cadmium on the hypothalamus-pituitary axis at different levels. This may lead to disorders of the endocrine and/or immune system. Cadmium exposure at early age should be limited as much as possible to prevent direct effects on children and to prevent accumulation of cadmium which may have serious health effects only becoming manifest at older age.

  16. Immunoassay for Cadmium Detection and Quantification

    Institute of Scientific and Technical Information of China (English)

    GONG-LIANG LIU; JU-FANG WANG; ZHI-YONG LI; SHI-ZHONG LIANG; XIAO-NING WANG

    2009-01-01

    Objective To detect cadmium in environmental and food samples by graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma atomic emission spectroscopy (ICPAES). Methods An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) was developed based on a cadmium-specific monoclonal antibody.IC-ELISA for cadmium in environmental and food samples was evaluated. Results IC-ELISA showed an IC50 of 45.6 μg/L with a detection limit of 1.95 μg/L for cadmium,and showed a mean recovery ranging 97.67%-107.08%.The coefficient of variations for intra- and iuterassay was 3.41%-6.61% and 4.70%-9.21%,respectively.The correlation coefficient between IC-ELISA and GFAAS was 0.998. Conclusion IC-ELISA can detect and quantify cadmium residue in environmental or food samples.

  17. Cadmium a metalloestrogen: are we convinced?

    Science.gov (United States)

    Silva, Nalinda; Peiris-John, Roshini; Wickremasinghe, Rajitha; Senanayake, Hemantha; Sathiakumar, Nalini

    2012-05-01

    Metalloestrogens are inorganic metal ions that bind to and activate oestrogen receptors. They are implicated in the aetiology of oestrogen-dependent diseases such as cancers of the breast and endometrium as well as endometriosis. Cadmium is one of the most studied metalloestrogens. In this review, scientific evidence for the oestrogenic effects of cadmium is critically evaluated to determine if there is sufficient evidence to support cadmium as an aetiological factor of oestrogen-dependent disease in humans. Results of the review indicated that, although the in vitro and in vivo evidence of the oestrogenic properties of cadmium was persuasive, evidence from population-based human studies remains conflicting. Considerable knowledge gaps exist on the potential oestrogenic effect of cadmium in humans. Research that focuses on bridging these knowledge gaps would be useful in preventing and managing oestrogen-dependent disease in humans.

  18. Thermo chemical stability of cadmium sulfide nanoparticles under intense pulsed light irradiation and high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Colorado, H.A., E-mail: hcoloradolopera@ucla.edu [Materials Science and Engineering Department, University of California, Los Angeles, CA 90095 (United States); Universidad de Antioquia, Mechanical Engineering, Medellin (Colombia); Dhage, S.R. [International Advanced Research Center for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005 (India); Hahn, H.T. [Materials Science and Engineering Department, University of California, Los Angeles, CA 90095 (United States); Mechanical and Aerospace Engineering Department, University of California, Los Angeles (United States)

    2011-09-15

    Highlights: > In this paper is about the thermochemical stability of CdS nanoparticles under Intense Pulsed Light (IPL) irradiation. > After few irradiation shots over the nano-particles, CdS pillars appeared without phase transformation. > No oxidation was observed during the treatment process. > CdS nanoparticles are thermally stable until around 400 deg. C and 600 deg. C for air and argon atmospheres respectively. > It has been studied and demonstrated the stability of CdS nanoparticles under intense pulsed light and under high temperature conditions. - Abstract: Thermo chemical stability of CdS nanoparticles under an Intense Pulsed Light from a xenon flash lamp and high temperature X-ray Diffraction (XRD) were investigated. The CdS nanoparticles were obtained with a chemical bath method. The CdSO{sub 4} (0.16 M) solution was added to an NH{sub 3} (7.5 M) solution under constant stirring. Afterwards, a thiourea (0.6 M) solution was added. The bath temperature and pH were maintained at 65 deg. C and 10, respectively and the mixture was stirred constantly until a solid precipitate of yellow CdS was produced. Its microstructure was investigated with Scanning Electron Microscopy, and its electronic properties were determined by UV-visible and Photo luminescence Spectroscopy. The microstructure of the sintered CdS nanoparticles, obtained the high temperature XRD, was investigated with EDAX and X-ray micro Tomography. In addition, high temperature XRD and Themogravimetric Analysis tests were conducted over the samples. The CdS nanoparticles' crystallinity increased with the irradiation exposure and they were thermally stable until 600 deg. C in argon atmosphere. However new phases start to appear after annealing at 400 deg. C for 30 min in air atmosphere. The main contribution of this paper was to investigate the stability of CdS nanoparticles under intense light and high temperature conditions. It was found that the number of irradiation shots conducted with the IPL technique increased the crystallinity of the CdS, by increasing the CdS nanopillars formation. A simple mechanism of ultra fast melting and cooling like quenching has been proposed to explain the phenomenon. It is also shown than at temperatures higher than 600 deg. C, different oxides appeared, while temperatures higher than 900 deg. C had a complete degradation of the CdS.

  19. Chemical spray pyrolysis of copper indium diselenide/cadmium sulfide solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Brown, B.J.

    1989-01-01

    This dissertation concentrates on Chemical Spray Pyrolysis (CSP) of CuInSe{sub 2} and CdS thin films and solar cells. The primary goal is to gain an understanding of the chemistry and physics of CSP, and apply this knowledge to the fabrication of CuInSe{sub 2}/CdS solar cells. It provide an extensive review of the literature on the properties of CuInSe{sub 2} an CdS produced by CSP and other techniques. The films are characterized by x-ray diffractometry, scanning electron microscopy, electron microprobe, van der Pauw-Hall measurements, and optical absorption spectroscopy, and the devices are characterized electrically in the dark and under illumination. A model for the chemical mechanisms involved in CSP of CdS an CuInSe{sub 2} thin films is developed which is used to point out similarities between the two systems and explain the correlation between spray solution pH and second phases in CuInSe{sub 2} thin films. Structural investigations show that the CuInSe{sub 2} films can be produced in either the ordered or disordered crystal structure, while different substrates radically change the morphology of the films. By taking into account the effect of second phases, the electrical and optical properties of the sprayed films agree with published results for CuInSe{sub 2} produced by other techniques. The properties of the sprayed CdS films in this work are shown to agree with those sprayed by others. The device properties of cells fabricated in both the backwall and reverse backwall configuration are compared with each other and related to the materials properties of the semiconductor layers. The highest efficiency cell employing sprayed CuInSe{sub 2} is reported; however, the efficiency of the cells still need improvement before becoming practical. The dissertation concludes with recommendations for increasing the efficiency of completely sprayed CuInSe{sub 2}/CdS solar cells.

  20. Determination of the band alignment of multi-walled carbon nanotubes decorated with cadmium sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.F.O., E-mail: mangos@ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Paniago, R.M., E-mail: paniago@fisica.ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Miquita, D.R., E-mail: douglas.miquita@gmail.com [Centro de Microscopia da Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Pinheiro, C.B., E-mail: basilio@fisica.ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Ladeira, L.O., E-mail: ladeira@fisica.ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Ferlauto, A.S., E-mail: ferlauto@fisica.ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Rodrigues, W.N., E-mail: wagner@fisica.ufmg.br [Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil); Centro de Microscopia da Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil)

    2014-12-01

    Highlights: • MWCNTs and CdS composite were grown by the solvothermal method. • Photoelectron spectroscopy was used to analyze energy levels at the interface. • The interface shows zero value for the Schottky barrier between MWCNTs and CdS. • MWCNTs act as ohmic contacts for CdS nanoparticles. • MWCNTs may act as charge collector in CdS-based devices.

  1. Growth analysis of cadmium sulfide thin films by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Dhere, R.G.; Ramanathan, K. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    CdS films have been deposited by solution growth on SnO{sub 2} and glass substrates. Nucleation on SnO{sub 2} occurs at early deposition times, and complete conformal coverage is observed at low thickness values. The average grain size of the CdS films is established at these early times. In films deposited on glass substrates, nucleation is slower and occurs through 3-dimensional islands that increase in size and number as deposition proceeds. Optical measurements show that the bandgap values of CdS films deposited on SnO{sub 2} depend mainly on substrate structure. Hydrogen heat treatment does not affect the surface morphology of the samples, but decreases bandgap values.

  2. Inorganic salt-induced phase control and optical characterization of cadmium sulfide nanoparticles

    Science.gov (United States)

    Tai, Guo'an; Zhou, Jianxin; Guo, Wanlin

    2010-04-01

    Phase-controlled synthesis of CdS nanoparticles from zinc-blende to wurtzite has been successfully realized by an inorganic salt-induced process with no use of surfactants or other ligands in an ultrasound-assisted microwave synthesis system. Pure zinc-blende CdS nanoparticles were produced without adding NaCl, while mixed zinc-blende and wurtzite nanoparticles were obtained by adding NaCl/Cd2 + molar ratios below 1, and pure wurtzite nanoparticles were produced at a molar ratio of 1. The energy bandgap (Eg) of the CdS nanoparticles calculated from optical absorption spectra increases as the phase transformation from zinc-blende to wurtzite occurs. Additionally, the CdS nanoparticles showed a 489 nm band-edge emission without adding NaCl, and a 501 nm emission when the molar ratios of NaCl to Cd2 + are 0.25, 0.5 and 1. It was found that the phase transformation originates from the effect of the halide ion Cl - . We also found that some other halide ions such as Br - and I - can induce the phase transformation. It is shown that the phase, size and optical properties of the anisotropic nanoparticles can be well tuned by varying the concentration of the halide ions.

  3. Inorganic salt-induced phase control and optical characterization of cadmium sulfide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Guo' an; Zhou Jianxin; Guo Wanlin, E-mail: taiguoan@nuaa.edu.cn, E-mail: wlguo@nuaa.edu.cn [Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)

    2010-04-30

    Phase-controlled synthesis of CdS nanoparticles from zinc-blende to wurtzite has been successfully realized by an inorganic salt-induced process with no use of surfactants or other ligands in an ultrasound-assisted microwave synthesis system. Pure zinc-blende CdS nanoparticles were produced without adding NaCl, while mixed zinc-blende and wurtzite nanoparticles were obtained by adding NaCl/Cd{sup 2+} molar ratios below 1, and pure wurtzite nanoparticles were produced at a molar ratio of 1. The energy bandgap (E{sub g}) of the CdS nanoparticles calculated from optical absorption spectra increases as the phase transformation from zinc-blende to wurtzite occurs. Additionally, the CdS nanoparticles showed a 489 nm band-edge emission without adding NaCl, and a 501 nm emission when the molar ratios of NaCl to Cd{sup 2+} are 0.25, 0.5 and 1. It was found that the phase transformation originates from the effect of the halide ion Cl{sup -}. We also found that some other halide ions such as Br{sup -} and I{sup -} can induce the phase transformation. It is shown that the phase, size and optical properties of the anisotropic nanoparticles can be well tuned by varying the concentration of the halide ions.

  4. Growth analysis of cadmium sulfide thin films by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Dhere, R.G.; Ramanathan, K.; Sheldon, P.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States)

    1996-09-01

    CdS films have been deposited by solution growth on SnO{sub 2} and glass substrates. Nucleation on SnO{sub 2} occurs at early deposition times, and complete conformal coverage is observed at low thickness values. The average grain size of the CdS films is established at these early times. In films deposited on glass substrates, nucleation is slower and occurs through 3-dimensional islands that increase in size and number as deposition proceeds. Optical measurements show that the bandgap values of CdS films deposited on SnO{sub 2} depend mainly on substrate structure. Hydrogen heat treatment does not affect the surface morphology of the samples, but decreases bandgap values.

  5. Highly Efficient Photocatalytic Hydrogen Production of Flower-like Cadmium Sulfide Decorated by Histidine

    Science.gov (United States)

    Wang, Qizhao; Lian, Juhong; Li, Jiajia; Wang, Rongfang; Huang, Haohao; Su, Bitao; Lei, Ziqiang

    2015-09-01

    Morphology-controlled synthesis of CdS can significantly enhance the efficiency of its photocatalytic hydrogen production. In this study, a novel three-dimensional (3D) flower-like CdS is synthesized via a facile template-free hydrothermal process using Cd(NO3)2•4H2O and thiourea as precursors and L-Histidine as a chelating agent. The morphology, crystal phase, and photoelectrochemical performance of the flower-like CdS and pure CdS nanocrystals are carefully investigated via various characterizations. Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS. On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution. The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. Furthermore, the photocatalytic contrast experiments illustrate that the as-synthesized flower-like CdS with L-Histidine is more stable than CdS without L-Histidine in the hydrogen generation.

  6. Plasma-enhanced microwave solid-state synthesis of cadmium sulfide: reaction mechanism and optical properties.

    Science.gov (United States)

    Du, Ke-zhao; Chaturvedi, Apoorva; Wang, Xing-zhi; Zhao, Yi; Zhang, Ke-ke; Iqbal Bakti Utama, M; Hu, Peng; Jiang, Hui; Xiong, Qi-hua; Kloc, Christian

    2015-08-14

    CdS synthesis by plasma-enhanced microwave physical vapor transport (PMPVT) has been developed in this work. The photoluminescence (PL), absorbance, Raman spectra and the mechanism of CdS crystal growth have been investigated. Furthermore, plasma-enhanced microwave chemical vapour transport (PMCVT) synthesis of CdS with additional chemical transport agents has been explored. In addition, other II-VI chalcogenides were also synthesized by PMPVT.

  7. 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.

  8. 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.

  9. Cadmium mobility and accumulation in soils of the European Communities

    NARCIS (Netherlands)

    Fraters B; van Beurden AUCJ

    1993-01-01

    In this overview of the effects of cadmium pollution on agricultural soils in the European Community, both the cadmium loads on agricultural land and the soil sensitivity to cadmium accumulation have been estimated. Cadmium loads have been estimated separately for arable land and grassland. The ef

  10. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  11. Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors

    NARCIS (Netherlands)

    Villa Gomez, D.K.; Cassidy, J.; Keesman, K.J.; Sampaio, R.M.; Lens, P.N.L.

    2014-01-01

    Step changes in the organic loading rate (OLR) through variations in the influent chemical oxygen demand (CODin) concentration or in the hydraulic retention time (HRT) at constant COD/SO4 2- ratio (0.67) were applied to create sulfide responses for the design of a sulfide control in sulfate reducing

  12. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    Science.gov (United States)

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  13. Hydrogen sulfide induces oxidative damage to RNA and DNA in a sulfide-tolerant marine invertebrate.

    Science.gov (United States)

    Joyner-Matos, Joanna; Predmore, Benjamin L; Stein, Jenny R; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes exposed in vitro to sulfide (0-3 mmol L(-1) for 1 h) showed dose-dependent increases in oxidative stress (as 2',7'-dichlorofluorescein fluorescence) and superoxide production (as dihydroethidine fluorescence). Coelomocytes exposed in vitro to sulfide (up to 0.73 mmol L(-1) for 2 h) also acquired increased oxidative damage to RNA (detected as 8-oxo-7,8-dihydroguanosine) and DNA (detected as 8-oxo-7,8-dihydro-2'-deoxyguanosine). Worms exposed in vivo to sulfide (0-10 mmol L(-1) for 24 h) acquired elevated oxidative damage to RNA and DNA in both coelomocytes and body wall tissue. While the consequences of RNA and DNA oxidative damage are poorly understood, oxidatively damaged deoxyguanosine bases preferentially bind thymine, causing G-T transversions and potentially causing heritable point mutations. This suggests that sulfide can be an environmental mutagen in sulfide-tolerant invertebrates.

  14. Combining experiment and theory to elucidate the role of supercritical water in sulfide decomposition.

    Science.gov (United States)

    Kida, Yuko; Class, Caleb A; Concepcion, Anthony J; Timko, Michael T; Green, William H

    2014-05-28

    The cleavage of C-S linkages plays a key role in fuel processing and organic geochemistry. Water is known to affect these processes, and several hypotheses have been proposed, but the mechanism has been elusive. Here we use both experiment and theory to demonstrate that supercritical water reacts with intermediates formed during alkyl sulfide decomposition. During hexyl sulfide decomposition in supercritical water, pentane and CO + CO2 were detected in addition to the expected six carbon products. A multi-step reaction sequence for hexyl sulfide reacting with supercritical water is proposed which explains the surprising products, and quantum chemical calculations provide quantitative rates that support the proposed mechanism. The key sequence is cleavage of one C-S bond to form a thioaldehyde via radical reactions, followed by a pericyclic addition of water to the C[double bond, length as m-dash]S bond to form a geminal mercaptoalcohol. The mercaptoalcohol decomposes into an aldehyde and H2S either directly or via a water-catalyzed 6-membered ring transition state. The aldehyde quickly decomposes into CO plus pentane by radical reactions. The time is ripe for quantitative modelling of organosulfur reaction kinetics based on modern quantum chemistry.

  15. Sealed nickel-cadmium battery

    Energy Technology Data Exchange (ETDEWEB)

    1989-08-15

    Overcharge protection, and especially the chargeability of a sealed Ni/Cd battery with high currents is improved by rolling a carbon-containing powdered material into the surface of the negative electrode, which material catalyzes the reduction of oxygen. Wetting of the electrode with a Tylose dispersion prior to application of the powder (by powdering, vibration or in an agitator) improves the adhesion of the powder. The cadmium electrode thus prepared combines in itself the functions of a negative principal electrode and of an auxiliary oxygen electrode.

  16. Quantum computing

    OpenAIRE

    Li, Shu-Shen; Long, Gui-lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi

    2001-01-01

    Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization.

  17. Response of Saccharomyces cerevisiae to cadmium stress

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Luciana Mara Costa; Ribeiro, Frederico Haddad; Neves, Maria Jose [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Lab. de Radiobiologia], e-mail: luamatu@uol.com.br; Porto, Barbara Abranches Araujo; Amaral, Angela M.; Menezes, Maria Angela B.C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Lab. de Ativacao Neutronica], e-mail: menezes@cdtn.br; Rosa, Carlos Augusto [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Microbiologia], e-mail: carlrosa@icb.ufmg

    2009-07-01

    The intensification of industrial activity has been greatly contributing with the increase of heavy metals in the environment. Among these heavy metals, cadmium becomes a serious pervasive environmental pollutant. The cadmium is a heavy metal with no biological function, very toxic and carcinogenic at low concentrations. The toxicity of cadmium and several other metals can be mainly attributed to the multiplicity of coordination complexes and clusters that they can form. Some aspects of the cellular response to cadmium were extensively investigated in the yeast Saccharomyces cerevisiae. The primary site of interaction between many toxic metals and microbial cells is the plasma membrane. Plasma-membrane permeabilisation has been reported in a variety of microorganisms following cadmium exposure, and is considered one mechanism of cadmium toxicity in the yeast. In this work, using the yeast strain S. cerevisiae W303-WT, we have investigated the relationships between Cd uptake and release of cellular metal ions (K{sup +} and Na{sup +}) using neutron activation technique. The neutron activation was an easy, rapid and suitable technique for doing these metal determinations on yeast cells; was observed the change in morphology of the strains during the process of Cd accumulation, these alterations were observed by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) during incorporation of cadmium. (author)

  18. Response of Pleurotus ostreatus to cadmium exposure

    Energy Technology Data Exchange (ETDEWEB)

    Favero, N.; Bressa, G.; Costa, P. (Univ. of Padua (Italy))

    1990-08-01

    The possibility of utilizing agroindustrial wastes in the production of edible, high-quality products (e.g., mushrooms) implies the risk of bringing toxic substances, such as heavy metals, into the human food chain. Thus, growth in the presence of cadmium and cadmium accumulation limits have been studied in the industrially cultivated fungus P. ostreatus. Fruit body production is substantially unaffected in the presence of 25, 139, and 285 mg Cd/kg of dried substrate. Cadmium concentration in fruit bodies is related to cadmium substrate level, the metal being present at higher levels in caps (22-56 mg/kg dry wt) than in stems (13-36 mg/kg dry wt). Concentration factor (CF), very low in the controls (about 2), further decreases in treated specimens. The presence of a cadmium control mechanism in this fungi species is suggested. Fruit body cadmium levels could, however, represent a risk for P. ostreatus consumers, according to FAO/WHO limits related to weekly cadmium intake.

  19. Interactions of cadmium and zinc during pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Sorell, T.L.

    1988-01-01

    The interactions of cadmium exposure and zinc during pregnancy were investigated by studying rats exposed to 0, 5, 50, or 100 ppm cadmium (as CdCl{sub 2}) in the drinking water from day 6 to day 20 of pregnancy. On day 20 of pregnancy, fetuses of rats exposed to 50 and 100 ppm of cadmium were slightly but significantly smaller than those of control animals. Fetal weight was negatively correlated with fetal cadmium concentration and positively correlated with fetal cadmium concentration. Significant fetal cadmium accumulation occurred in both the 50 and 100 ppm cadmium exposure groups; fetal zinc concentrations were decreased. Maternal liver and kidney zinc concentrations were slightly elevated, and the possible role of maternal organ sequestration of available zinc is discussed. The activity of two zinc metalloenzymes, alkaline phosphatase and {delta}-aminolevulinic acid dehydratase, was decreased in maternal and fetal tissues, providing evidence of an alteration in zinc metabolism. In addition, the placental transport of {sup 65}Zn was characterized in control animals and compared to exposed groups; placental zinc transport was significantly decreased in the 50 and 100 ppm exposure groups.

  20. Cadmium inhalation and male reproductive toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Ragan, H.A.; Mast, T.J. (Battelle Pacific Northwest Laboratories, Richland, WA (USA))

    1990-01-01

    Cadmium is a highly toxic element that is cumulative and has a long biological half-life in mammals. The severe toxicity of cadmium in man has been known for more than 100 years. Despite the knowledge that cadmium is toxic, only 20 human cases of poisoning via ingestion were recorded prior to 1941, whereas in the ensuing five-year period more than 680 cases of cadmium poisonings from accidental oral ingestion of this metal were documented. Some of the recorded effects of exposure to cadmium in laboratory animals include renal tubular damage, placental and testicular necrosis, structural and functional liver damage, osteomalacia, testicular tumors, teratogenic malformations, anemia, hypertension, pulmonary edema, chronic pulmonary emphysema, and induced deficiencies of iron, copper, and zinc. Some of these effects have also been observed in human after accidental exposures to cadmium oxide fumes and are characteristic of the syndrome described in Japan as Itai Itai disease in which ingestion of cadmium is the inciting chemical.134 references.

  1. Sulfide capacities of fayalite-base slags

    Science.gov (United States)

    Simeonov, S. R.; Sridhar, R.; Toguri, J. M.

    1995-04-01

    The sulfide capacities of fayalite-base slags were measured by a gas-slag equilibration technique under controlled oxygen and sulfur potentials similar to those encountered in the pyrometallurgical processing of nonferrous metals. The oxygen pressure range was from 10-9.5 to 10-11 MPa and the sulfur pressure range from 10-3 to 10-4.5 MPa, over a temperature range of 1473 to 1623 K. The slags studied were FeO-SiO2 at silica saturation and those with addition of CaO, MgO, and Al2O3 to determine their effect on sulfide capacities. For these slags, the sulfide capacities were found to vary from 10-3.3 to 10-5. The sulfide capacities increased with increasing temperature from 1473 to 1623 K. A comparison of the reported plant data on sulfur content of industrial slags shows good agreement with the present experimental results. The present data will be useful in estimating metal losses in slag due to metal sulfide entrainment in nonferrous smelters.

  2. [Association between cadmium and breast cancer].

    Science.gov (United States)

    Strumylaite, Loreta; Bogusevicius, Algirdas; Ryselis, Stanislovas; Pranys, Darius; Poskiene, Lina; Kregzdyte, Rima; Abdrachmanovas, Olegas; Asadauskaite, Rūta

    2008-01-01

    Cadmium is a known human lung carcinogen, although some studies indicate a link between cadmium exposure and human breast cancer. The objective of this study was to assess cadmium concentration in breast tissue samples of patients with breast cancer and benign breast tumor. MATERIAL AND METHODS. The concentration of cadmium was determined in breast tissue samples of 21 breast cancer and 19 benign tumor patients. Two samples of breast tissue from each patient, i.e. tumor and normal tissue close to tumor, were taken for the analysis. Cadmium was determined by atomic absorption spectrometry (Perkin-Elmer, Zeeman 3030). RESULTS. In patients with breast cancer, the mean cadmium concentration was 33.1 ng/g (95% CI, 21.9-44.4) in malignant breast tissue and 10.4 ng/g (95% CI, 5.6-15.2) in normal breast tissue (P=0.002). In patients with benign tumor, the corresponding values were 17.5 ng/g (95% CI, 8.4-26.5) and 11.8 ng/g (95% CI, 5.1-18.5) (P=0.3144). There was a statistically significant difference in cadmium concentration between malignant and benign breast tissues (P=0.009). CONCLUSION. The data obtained show that cadmium concentration is significantly higher in malignant breast tissue as compared with normal breast tissue of the same women or benign breast tissue. Further studies are necessary to determine the association between cadmium concentration in malignant breast tissue and estrogen receptor level, and smoking.

  3. Biochemical Effects of Cadmium Exposure and the Potential Pharmacologic Significance of Cadmium Mediated Hydrolase Inhibition

    Science.gov (United States)

    1997-04-18

    increase Cd absorption from the intestines (Larson and Piscator 1971; Itokawa, Abe et al. 197 4; Pond and Walker 1975). Pyridoxine, vitamin B 6 , is...considerations on uptake and retention of cadmium in human kidney cortex. Cadmium in the Environment. L. Friberg, M. Piscator and G. F. Nordberg. Cleveland...Columbia, Missouri, University of Missouri. Larson, S.-E. and M. Piscator (1971). "Effect of cadmium on skeletal tissue in normal and calcium

  4. Cadmium Toxicity to Ringed Seals (Phoca hispida)

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, R.; Riget, F. F.;

    as laboratory mammals. We have studied possible cadmium induced histopathological changes in the kidneys as well as a demineralisation of the skeletal system (DXA-scanning of lumbal vertebraes). No obvious cadmium induced toxic changes were found. Food composition and physiological adaptations may explain......Cadmium concentrations in kidneys from ringed seals (Phoca hispida) from North West Greenland (Qaanaaq) are high. Concentrations range at level known to induce renal toxic effects (mainly tubulopathy) and demineralisation (osteopenia) of the skeletal system (Fanconi's Syndrome) in humans as well...

  5. Quantum Distinction: Quantum Distinctiones!

    OpenAIRE

    Zeps, Dainis

    2009-01-01

    10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...

  6. Synthesis of CdSe Quantum Dots Using Fusarium oxysporum

    OpenAIRE

    Takaaki Yamaguchi; Yoshijiro Tsuruda; Tomohiro Furukawa; Lumi Negishi; Yuki Imura; Shohei Sakuda; Etsuro Yoshimura; Michio Suzuki

    2016-01-01

    CdSe quantum dots are often used in industry as fluorescent materials. In this study, CdSe quantum dots were synthesized using Fusarium oxysporum. The cadmium and selenium concentration, pH, and temperature for the culture of F. oxysporum (Fusarium oxysporum) were optimized for the synthesis, and the CdSe quantum dots obtained from the mycelial cells of F. oxysporum were observed by transmission electron microscopy. Ultra-thin sections of F. oxysporum showed that the CdSe quantum dots were pr...

  7. Solar thermal extraction of copper from sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Guesdon, C.; Sturzenegger, M.

    2003-03-01

    With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates re-search on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite (Cu{sub 2}S) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS{sub 2}) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO{sub 2}, and is beneficial to the removal of volatile impurities. Chemical equilibrium calculations for CuFeS{sub 2} contaminated with enargite (Cu{sub 3}AsS{sub 4}) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation. (author)

  8. Sulfide and methane production in sewer sediments.

    Science.gov (United States)

    Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

    2015-03-01

    Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

  9. Membrane for hydrogen recovery from streams containing hydrogen sulfide

    Science.gov (United States)

    Agarwal, Pradeep K.

    2007-01-16

    A membrane for hydrogen recovery from streams containing hydrogen sulfide is provided. The membrane comprises a substrate, a hydrogen permeable first membrane layer deposited on the substrate, and a second membrane layer deposited on the first layer. The second layer contains sulfides of transition metals and positioned on the on a feed side of the hydrogen sulfide stream. The present invention also includes a method for the direct decomposition of hydrogen sulfide to hydrogen and sulfur.

  10. Acute inhalation toxicity of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Benson, J.M.; Hahn, F.F.; Barr, E.B. [and others

    1995-12-01

    Carbonyl sulfide (COS), a colorless gas, is a side product of industrial procedures sure as coal hydrogenation and gasification. It is structurally related to and is a metabolite of carbon disulfide. COS is metabolized in the body by carbonic anhydrase to hydrogen sulfide (H{sub 2}S), which is thought to be responsible for COS toxicity. No threshold limit value for COS has been established. Results of these studies indicate COS (with an LC{sub 50} of 590 ppm) is slightly less acutely toxic than H{sub 2}S (LC{sub 50} of 440 ppm).

  11. Modeling of Sulfide Microenvironments on Mars

    Science.gov (United States)

    Schwenzer, S. P.; Bridges, J. C.; McAdam, A.; Steer, E. D.; Conrad, P. G.; Kelley, S. P.; Wiens, R. C.; Mangold, N.; Grotzinger, J.; Eigenbrode, J. L.; Franz, H. B.; Sutter, B.

    2016-01-01

    Yellowknife Bay (YKB; sol 124-198) is the second site that the Mars Science Laboratory Rover Curiosity investigated in detail on its mission in Gale Crater. YKB represents lake bed sediments from an overall neutral pH, low salinity environment, with a mineralogical composition which includes Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral phyllosilicates. We investigate whether sulfide alteration could be associated with ancient habitable microenvironments in the Gale mudstones. Some textural evidence for such alteration may be pre-sent in the nodules present in the mudstone.

  12. Iron-sulfide crystals in probe deposits

    DEFF Research Database (Denmark)

    Laursen, Karin; Frandsen, Flemming

    1998-01-01

    Iron-sulfides were observed in deposits collected on a probe inserted at the top of the furnace of a coal-fired power station in Denmark. The chemical composition of the iron-sulfides is equivalent to pyrrhotite (FeS). The pyrrhotites are present as crystals and, based on the shape of the crystals......, it was deduced that they were not deposited but instead grew within the deposit. The presence of unburned char particles within the deposits supports the concept that a reducing environment existed in the deposits. Two processes are proposed for explaining the existence of pyrrhotite crystals within a deposit...

  13. Cu-doped ZnO nanoporous film for improved performance of CdS/CdSe quantum dot-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Myeong-Soo; Son, Min-Kyu; Kim, Soo-Kyoung; Park, Songyi; Prabakar, Kandasamy; Kim, Hee-Je, E-mail: heeje@pusan.ac.kr

    2014-11-03

    Copper (Cu) doped zinc oxide (ZnO) powders were synthesized by co-precipitation method with different at% (0 and 0.5 at%) of Cu dopant. Cu-doped ZnO nanoporous (NP) films were fabricated to enhance the performance of the ZnO based cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dot-sensitized solar cells (QDSSCs). The existence of Cu ions in the Cu-doped ZnO NP film was detected by X-ray fluorescence. The surface morphology, microstructure and crystal structure of Cu-doped ZnO NP films were analyzed by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The optical property of CdS/CdSe co-sensitized Cu-doped ZnO NP film was studied by UV–vis absorption spectroscopy. The photovoltaic performance and electrical property of Cu-doped ZnO CdS/CdSe QDSSCs were studied by current–voltage characteristic curves and electrochemical impedance spectroscopy under air mass 1.5 condition. As a result, short circuit current density and fill factor increased from 9.074 mA/cm{sup 2} and 0.403 to 9.865 mA/cm{sup 2} and 0.427 respectively, based on the enhanced absorbance and electron transport by Cu-doping. This led to the increasing light conversion efficiency from 2.27% to 2.61%. - Highlights: • Cu-doped ZnO powders were synthesized by co-precipitation method. • Cu-doped ZnO nanoporous films with high crystallinity were uniformly deposited. • Absorbance of Cu-doped ZnO nanoporous film was enhanced. • Electron conductivity of Cu-doped ZnO nanoporous film was enhanced. • Performance of Cu-doped ZnO CdS/CdSe QDSSC was improved.

  14. Use of biogenic sulfide for ZnS precipitation

    NARCIS (Netherlands)

    Esposito, G.; Veeken, A.; Weijma, J.; Lens, P.N.L.

    2006-01-01

    A 600 ml continuously stirred tank reactor was used to assess the performance of a zinc sulfide precipitation process using a biogenic sulfide solution (the effluent of a sulfate-reducing bioreactor) as sulfide source. In all experiments, a proportional-integral (PI) control algorithm was used to co

  15. A physiologically based kinetic model for bacterial sulfide oxidation

    NARCIS (Netherlands)

    Klok, J.B.; Graaff, M. de; Bosch, P.L. van den; Boelee, N.C.; Keesman, K.J.; Janssen, A.J.W.M.

    2013-01-01

    In the biotechnological process for hydrogen sulfide removal from gas streams, a variety of oxidation products can be formed. Under natron-alkaline conditions, sulfide is oxidized by haloalkaliphilic sulfide oxidizing bacteria via flavocytochrome c oxidoreductase. From previous studies, it was concl

  16. Reducing charge trapping in PbS colloidal quantum dot solids

    NARCIS (Netherlands)

    Balazs, D. M.; Nugraha, M. I.; Bisri, S. Z.; Sytnyk, M.; Heiss, W.; Loi, M. A.

    2014-01-01

    Understanding and improving charge transport in colloidal quantum dot solids is crucial for the development of efficient solar cells based on these materials. In this paper, we report high performance field-effect transistors based on lead-sulfide colloidal quantum dots (PbS CQDs) crosslinked with 3

  17. 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...

  18. Pressure tuning of strains in Zn{sub 1-x}Cd{sub x}Se/ZnSe single quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z.Z.; Liang, X.X.; Ban, S.L

    2002-12-30

    The pressure tuning of strains in ZnCdSe/ZnSe single quantum wells is studied theoretically. It is shown that the tuning can still occur before the structural phase transition for the quantum wells with small Cadmium content and thinner ZnSe/ZnCdSe layers. The effects of the Cadmium content change on the tuning pressure and the separation between the heavy hole and the light hole are also demonstrated.

  19. Some Aspects of Sealed Nickel Cadmium Cells

    Directory of Open Access Journals (Sweden)

    P. K. Saha

    1967-11-01

    Full Text Available Sealed Nickel Cadmium Cell system is termed till today as the most reliable power pack for electronic apparatus specially in low temperature use. This paper brings out the development and production of sealed nickel cadmium cells of pocket plate construction. The author who has gained experience in production of Ni-Cd cells in East Germany discusses also the major problems faced by the battery manufactures of to-day.

  20. Effect of Al 2 O 3 Recombination Barrier Layers Deposited by Atomic Layer Deposition in Solid-State CdS Quantum Dot-Sensitized Solar Cells

    KAUST Repository

    Roelofs, Katherine E.

    2013-03-21

    Despite the promise of quantum dots (QDs) as a light-absorbing material to replace the dye in dye-sensitized solar cells, quantum dot-sensitized solar cell (QDSSC) efficiencies remain low, due in part to high rates of recombination. In this article, we demonstrate that ultrathin recombination barrier layers of Al2O3 deposited by atomic layer deposition can improve the performance of cadmium sulfide (CdS) quantum dot-sensitized solar cells with spiro-OMeTAD as the solid-state hole transport material. We explored depositing the Al2O3 barrier layers either before or after the QDs, resulting in TiO2/Al2O3/QD and TiO 2/QD/Al2O3 configurations. The effects of barrier layer configuration and thickness were tracked through current-voltage measurements of device performance and transient photovoltage measurements of electron lifetimes. The Al2O3 layers were found to suppress dark current and increase electron lifetimes with increasing Al 2O3 thickness in both configurations. For thin barrier layers, gains in open-circuit voltage and concomitant increases in efficiency were observed, although at greater thicknesses, losses in photocurrent caused net decreases in efficiency. A close comparison of the electron lifetimes in TiO2 in the TiO2/Al2O3/QD and TiO2/QD/Al2O3 configurations suggests that electron transfer from TiO2 to spiro-OMeTAD is a major source of recombination in ss-QDSSCs, though recombination of TiO2 electrons with oxidized QDs can also limit electron lifetimes, particularly if the regeneration of oxidized QDs is hindered by a too-thick coating of the barrier layer. © 2013 American Chemical Society.

  1. Screening micro-organisms for cadmium absorption from aqueous solution and cadmium absorption properties of Arthrobacter nicotianae.

    Science.gov (United States)

    Tsuruta, Takehiko; Umenai, Daishi; Hatano, Tomonobu; Hirajima, Tsuyoshi; Sasaki, Keiko

    2014-01-01

    To obtain basic information on how microbial cells absorb cadmium from aqueous solution, we examined cadmium absorption in various micro-organisms. Of 51 micro-organism strains tested, we found that some Gram-positive bacteria, such as, Arthrobacter nicotianae and Bacillus subtilis, and some actinomycetes, such as, Streptomyces flavoviridis and S. levoris were highly capable of absorbing cadmium from an aqueous solution. A. nicotianae absorbed the largest amount of cadmium, over 800 μmol cadmium per gram of dry wt. cells. However, cadmium absorption by A. nicotianae was affected by the solution pH, cadmium concentration, and cell density. The absorption of cadmium was very rapid. Some factors that affected cadmium absorption by A. nicotianae cells were also discussed.

  2. Cadmium exposure and breast cancer risk.

    Science.gov (United States)

    McElroy, Jane A; Shafer, Martin M; Trentham-Dietz, Amy; Hampton, John M; Newcomb, Polly A

    2006-06-21

    Cadmium, a highly persistent heavy metal, has been categorized as a probable human carcinogen by the U.S. Environmental Protection Agency. Primary exposure sources include food and tobacco smoke. We carried out a population-based case-control study of 246 women, aged 20-69 years, with breast cancer and 254 age-matched control subjects. We measured cadmium levels in urine samples by inductively coupled plasma mass spectrometry and conducted interviews by telephone to obtain information on known breast cancer risk factors. Odds ratios (ORs) and 95% confidence intervals (CIs) for breast cancer by creatinine-adjusted cadmium levels were calculated by multivariable analysis. Statistical tests were two-sided. Women in the highest quartile of creatinine-adjusted cadmium level (> or = 0.58 microg/g) had twice the breast cancer risk of those in the lowest quartile (cadmium level (P(trend) = .01). Based on this study, the absolute risk difference is 45 (95% CI = 0 to 77) per 100,000 given an overall breast cancer rate of 124 per 100,000. Whether increased cadmium is a causal factor for breast cancer or reflects the effects of treatment or disease remains to be determined.

  3. Cadmium contamination of agricultural soils and crops resulting from sphalerite weathering.

    Science.gov (United States)

    Robson, T C; Braungardt, C B; Rieuwerts, J; Worsfold, P

    2014-01-01

    The biogeochemistry and bioavailability of cadmium, released during sphalerite weathering in soils, were investigated under contrasting agricultural scenarios to assess health risks associated with sphalerite dust transport to productive soils from mining. Laboratory experiments (365 d) on temperate and sub-tropical soils amended with sphalerite (soil accumulated ≈38% (29 μmol kg(-1)) of the liberated Cd, exceeding food safety limits. In contrast, rice grown in flooded sub-tropical soil accumulated far less Cd (0.60 μmol kg(-1)) due to neutral soil pH and Cd bioavailability was possibly also controlled by secondary sulfide formation. The results demonstrate long-term release of Cd to soil porewaters during sphalerite weathering. Under oxic conditions, Cd may be sufficiently bioavailable to contaminate crops destined for human consumption; however flooded rice production limits the impact of sphalerite contamination.

  4. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices.

    NARCIS (Netherlands)

    Tangerman, A.

    2009-01-01

    This review deals with the measurement of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  5. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices

    NARCIS (Netherlands)

    Tangerman, Albert

    2009-01-01

    This review deals with the measurement of the volatile Sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  6. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco

    DEFF Research Database (Denmark)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild;

    2015-01-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree...... such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers...... (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit...

  7. Comparison of Hydrogen Sulfide Analysis Techniques

    Science.gov (United States)

    Bethea, Robert M.

    1973-01-01

    A summary and critique of common methods of hydrogen sulfide analysis is presented. Procedures described are: reflectance from silver plates and lead acetate-coated tiles, lead acetate and mercuric chloride paper tapes, sodium nitroprusside and methylene blue wet chemical methods, infrared spectrophotometry, and gas chromatography. (BL)

  8. Microbial Fuel Cells for Sulfide Removal

    NARCIS (Netherlands)

    Rabaey, K.; Sompel, van de S.; Maignien, L.; Boon, N.; Aelterman, P.; Clauwaert, P.; Schamphelaire, de L.; The Pham, H.; Vermeulen, J.; Verhaege, M.; Lens, P.N.L.; Verstraete, W.

    2006-01-01

    Thus far, microbial fuel cells (MFCs) have been used to convert carbon-based substrates to electricity. However, sulfur compounds are ubiquitously present in organic waste and wastewater. In this study, a MFC with a hexacyanoferrate cathodic electrolyte was used to convert dissolved sulfide to eleme

  9. 30 CFR 250.490 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... been confirmed. Well-control fluid means drilling mud and completion or workover fluid as appropriate... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Drilling Operations Hydrogen Sulfide § 250.490 Hydrogen... section when conducting drilling, well-completion/well-workover, and production operations in zones...

  10. Hydrogen Sulfide in Preeclampsia : Potential Therapeutic Implications

    NARCIS (Netherlands)

    Holwerda, Kim

    2015-01-01

    The thesis provide insights into the production and possible therapeutic effect of the gaseous molecule hydrogen sulfide (H2S) in preeclampsia (PE). H2S is an important molecule in the (human) body. It is among others involved in blood pressure regulation, stimulation of vascular growth and modulati

  11. Nucleation of mercury sulfide by dealkylation

    Science.gov (United States)

    Enescu, Mironel; Nagy, Kathryn L.; Manceau, Alain

    2016-12-01

    Metal sulfide minerals are assumed to form naturally at ambient conditions via reaction of a metallic element with (poly)sulfide ions, usually produced by microbes in oxygen-depleted environments. Recently, the formation of mercury sulfide (β-HgS) directly from linear Hg(II)-thiolate complexes (Hg(SR)2) in natural organic matter and in cysteine solutions was demonstrated under aerated conditions. Here, a detailed description of this non-sulfidic reaction is provided by computations at a high level of molecular-orbital theory. The HgS stoichiometry is obtained through the cleavage of the S-C bond in one thiolate, transfer of the resulting alkyl group (R’) to another thiolate, and subsequent elimination of a sulfur atom from the second thiolate as a thioether (RSR’). Repetition of this mechanism leads to the formation of RS-(HgS)n-R chains which may self-assemble in parallel arrays to form cinnabar (α-HgS), or more commonly, quickly condense to four-coordinate metacinnabar (β-HgS). The mechanistic pathway is thermodynamically favorable and its predicted kinetics agrees with experiment. The results provide robust theoretical support for the abiotic natural formation of nanoparticulate HgS under oxic conditions and in the absence of a catalyst, and suggest a new route for the (bio)synthesis of HgS nanoparticles with improved technological properties.

  12. Platinum metals in magmatic sulfide ores

    Science.gov (United States)

    Naldrett, A.J.; Duke, J.M.

    1980-01-01

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. Copyright ?? 1980 AAAS.

  13. Monitoring sulfide and sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.S.

    1995-12-31

    Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

  14. Reviews of the environmental effects of pollutants: IV. Cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Hammons, A.S.; Huff, J.E.; Braunstein, H.M.; Drury, J.S.; Shriner, C.R.; Lewis, E.B.; Whitfield, B.L.; Towill, L.E.

    1978-06-01

    This report is a comprehensive, multidisciplinary review of the health and environmental effects of cadmium and specific cadmium derivatives. More than 500 references are cited. The cadmium body burden in animals and humans results mainly from the diet. In the United States, the normal intake of cadmium for adult humans is estimated at about 50 ..mu..g per day. Tobacco smoke is a significant additional source of cadmium exposure. The kidneys and liver together contain about 50% of the total cadmium body burden. Acute cadmium poisoning is primarily an occupational problem, generally from inhalation of cadmium fumes or dusts. In the general population, incidents of acute poisoning by inhaled or ingested cadmium or its compounds are relatively rare. The kidney is the primary target organ for toxicity from prolonged low-level exposure to cadmium. No causal relationship has been established between cadmium exposure and human cancer, although a possible link between cadmium and prostate cancer has been indicated. Cadmium has been shown to be teratogenic in rats, hamsters, and mice, but no such effects have been proven in humans. Cadmium has been reported to increase the frequency of chromosomal aberrations in cultured Chinese hamster ovary cells and in human peripheral leukocytes. The major concern about environmental cadmium is the potential effects on the general population. There is no substantial evidence of hazard from current levels of cadmium in air, water, or food. However, because cadmium is a cumulative poison and because present intake provides a relatively small safety margin, there are adequate reasons for concern over possible future increases in background levels.

  15. CdS quantum dots as fluorescence probes for the sensitive and selective detection of highly reactive HSe- ions in aqueous solution.

    Science.gov (United States)

    Wu, Chuan-Liu; Zhao, Yi-Bing

    2007-06-01

    Water-soluble cadmium sulfide (CdS) quantum dots (QDs) capped by mercaptoacetic acid were synthesized by aqueous-phase arrested precipitation, and characterized by transmission electron microscopy, spectrofluorometry, and UV-Vis spectrophotometry. The prepared luminescent water-soluble CdS QDs were evaluated as fluorescence probes for the detection of highly reactive hydrogen selenide ions (HSe(-) ions). The quenching of the fluorescence emission of CdS QDs with the addition of HSe(-) ions is due to the elimination of the S(2-) vacancies which are luminescence centers. Quantitative analysis based on chemical interaction between HSe(-) ions and the surface of CdS QDs is very simple, easy to develop, and has demonstrated very high sensitivity and selectivity features. The effect of foreign ions (common anions and biologically relevant cations) on the fluorescence of the CdS QDs was examined to evaluate the selectivity. Only Cu(2+) and S(2-) ions exhibit significant effects on the fluorescence of CdS QDs. With the developed method, we are able to determine the concentration of HSe(-) ions in the range from 0.10 to 4.80 micromol L(-1), and the limit of detection is 0.087 micromol L(-1). The proposed method was successfully applied to monitor the obtained HSe(-) ions from the reaction of glutathione with selenite. To the best of our knowledge, this is the first report on fluorescence analysis of HSe(-) ions in aqueous solution.

  16. Selective turn-on fluorescence sensor for Ag+ using cysteamine capped CdS quantum dots: determination of free Ag+ in silver nanoparticles solution.

    Science.gov (United States)

    Khantaw, Thitima; Boonmee, Chanida; Tuntulani, Thawatchai; Ngeontae, Wittaya

    2013-10-15

    Cadmium sulfide quantum dots capped with cysteamine (Cys-CdS QDs) were demonstrated as a selective fluorescence probe for sensing of free trace silver ions. The fluorescence intensity of the Cys-CdS QDs can be enhanced only in the presence of free Ag(+) and the fluorescence spectrum was slightly red shift from the original spectra. In addition, the fluorescence intensities were linearly increased upon increasing Ag(+) concentration. At the optimized condition for Ag(+) detection, when adding other metal ions to the Cys-CdS QDs solution, fluorescence spectra of Cys-CdS QDs did not change significantly revealing good selectivity of the sensors towards Ag(+). The working linear concentration range was found to be 0.1-1.5 µM with LOD of 68 nM. The proposed sensor was then applied to detect free Ag(+) in the silver nanoparticles solution. The results showed that the proposed sensor can be efficiently used with good accuracy and precision providing the simple method for detection of free Ag(+) in silver nanoparticles of quality control products.

  17. Sulfide Intrusion and Detoxification in the Seagrass Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2015-01-01

    Gaseous sulfide intrusion into seagrasses growing in sulfidic sediments causes little or no harm to the plant, indicating the presence of an unknown sulfide tolerance or detoxification mechanism. We assessed such mechanism in the seagrass Zostera marina in the laboratory and in the field with sca......Gaseous sulfide intrusion into seagrasses growing in sulfidic sediments causes little or no harm to the plant, indicating the presence of an unknown sulfide tolerance or detoxification mechanism. We assessed such mechanism in the seagrass Zostera marina in the laboratory and in the field...... with scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, chromatographic and spectrophotometric methods, and stable isotope tracing coupled with a mass balance of sulfur compounds. We found that Z. marina detoxified gaseous sediment-derived sulfide through incorporation and that most...

  18. Sulfide removal by moderate oxygenation of anaerobic sludge environments

    Energy Technology Data Exchange (ETDEWEB)

    Van der Zee, F.P.; Villaverde, S.; Polanco, F. [Valladolid Univ., Valladolid (Spain). Dept. of Chemical Engineering; Garcia, P.A.

    2004-07-01

    Treating wastewater through anaerobic bioreactors results in the formation of hydrogen sulfide. The sulfide can be removed from the biogas by introducing air directly into the anaerobic bioreactor system. This study presents the results of batch experiments that provided a better insight into the fate of sulfur compounds and oxygen during microaerobic sulfide oxidation in granular sludge. It was shown that sulfide could be removed rapidly upon introduction of low amounts of oxygen to the sulfide-amended batch vials with granular sludge treating vinasse. Initially, the sulfide was oxidized to elemental sulfur, thiosulfate and polysulfide. Significant production of sulfate did not occur. The introduction of oxygen, however, could result in the growth of aerobic organic-chemical oxygen demand-oxidizing bacteria that compete with sulfide oxidation for oxygen. 6 refs., 1 tab., 1 fig.

  19. Experimental and theoretical investigations of cadmium diffusion in vacancy-rich Cu(In, Ga)Se2 material

    Science.gov (United States)

    Biderman, Norbert J.

    Copper indium gallium selenide (Cu(In,Ga)Se2 or CIGS) has become a significant topic of research and development for photovoltaic application. CIGS photovoltaic devices have demonstrated record conversion efficiencies however are still below the maximum solar conversion efficiency. Losses in performance have been attributed structural defects including vacancies, doping, grain boundaries, and compositional non-uniformity that are poorly understood and controlled. The cadmium sulfide (CdS) buffer layer plays a critical role in high-performance CIGS photovoltaic devices, serving as the n-type component of the p-n junction formed with the p-type CIGS absorber layer. Cadmium diffusion into the CIGS surface during CdS deposition creates a buried p-n homojunction in addition to the CIGS/CdS p-n heterojunction. CdS is believed to assist in reducing carrier recombination at the CIGS/CdS interface, an important attribute of high-efficiency solar cells. In the present work, cadmium diffusion mechanisms in CIGS are experimentally investigated via secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES). Two cadmium diffusion profiles with distinct Arrhenius diffusion kinetics within a single depth profile of the CIGS thin film are observed with SIMS and AES: an intense first-stage diffusion profile directly below the CIGS/CdS interface and a long-range, second-stage diffusion profile that extends deep into the thin film. Cadmium grain boundary diffusion is also detected in fine-grain CIGS samples. These multiple diffusion processes are quantified in the present work, and the two-stage cadmium diffusion profiles suggest distinctive lattice diffusion mechanisms. Calculations and modeling of general impurity diffusion via interstitial sites in CIGS are also conducted via numerical including cadmium, iron, and zinc. In the numerical simulations, the standard diffusion-reaction kinetics theory is extended to vacancy-rich materials like CIGS that contain 1 at

  20. Quantum Computing

    CERN Document Server

    Steane, A M

    1998-01-01

    The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. This review aims to summarise not just quantum computing, but the whole subject of quantum information theory. It turns out that information theory and quantum mechanics fit together very well. In order to explain their relationship, the review begins with an introduction to classical information theory and computer science, including Shannon's theorem, error correcting codes, Turing machines and computational complexity. The principles of quantum mechanics are then outlined, and the EPR experiment described. The EPR-Bell correlations, and quantum entanglement in general, form the essential new ingredient which distinguishes quantum from classical information theory, and, arguably, quantum from classical physics. Basic quantum information ideas are described, including key distribution, teleportation, data compression, quantum error correction, the universal quantum computer and qua...

  1. Quantum stochastics

    CERN Document Server

    Chang, Mou-Hsiung

    2015-01-01

    The classical probability theory initiated by Kolmogorov and its quantum counterpart, pioneered by von Neumann, were created at about the same time in the 1930s, but development of the quantum theory has trailed far behind. Although highly appealing, the quantum theory has a steep learning curve, requiring tools from both probability and analysis and a facility for combining the two viewpoints. This book is a systematic, self-contained account of the core of quantum probability and quantum stochastic processes for graduate students and researchers. The only assumed background is knowledge of the basic theory of Hilbert spaces, bounded linear operators, and classical Markov processes. From there, the book introduces additional tools from analysis, and then builds the quantum probability framework needed to support applications to quantum control and quantum information and communication. These include quantum noise, quantum stochastic calculus, stochastic quantum differential equations, quantum Markov semigrou...

  2. Identification of three relationships linking cadmium accumulation to cadmium tolerance and zinc and citrate accumulation in lettuce.

    Science.gov (United States)

    Zorrig, Walid; Rouached, Aïda; Shahzad, Zaigham; Abdelly, Chedly; Davidian, Jean-Claude; Berthomieu, Pierre

    2010-10-15

    Lettuce (Lactuca sativa) is a plant species that shows high accumulation of cadmium, a toxic heavy metal. Lettuce is therefore a good model both for identifying determinants controlling cadmium accumulation in plant tissues and for developing breeding strategies aimed at limiting cadmium accumulation in edible tissues. In this work, 14-day-old plants from three lettuce varieties were grown for 8 days on media supplemented with cadmium concentrations ranging from 0 to 50 microM. Growth, as well as Cd(2+), Zn(2+), K(+), Ca(2+), NO(3)(-), SO(4)(2-), Cl(-), phosphate, malate and citrate root an shoot contents were analyzed. The three lettuce varieties Paris Island Cos, Red Salad Bowl and Kordaat displayed differential abilities to accumulate cadmium in roots and shoots, Paris Island Cos displaying the lowest cadmium content and Kordaat the highest. From the global analysis of the three varieties, three main trends were identified. First, a common negative correlation linked cadmium tissue content and relative dry weight reduction in response to cadmium treatments in the three varieties. Second, increasing cadmium concentration in the culture medium resulted in a parallel increase in zinc tissue content in all lettuce varieties. A common strong positive correlation between cadmium and zinc contents was observed for all varieties. This suggested that systems enabling zinc and cadmium transport were induced by cadmium. Finally, the cadmium treatments had a contrasting effect on anion contents in tissues. Interestingly, citrate content in shoots was correlated with cadmium translocation from roots to shoots, suggesting that citrate might play a role in cadmium transport in the xylem vessels. Altogether, these results shed light on three main strategies developed by lettuce to cope with cadmium, which could help to develop breeding strategies aimed at limiting cadmium accumulation in lettuce.

  3. Quantum Blobs

    OpenAIRE

    Gosson, Maurice A. de

    2012-01-01

    Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level set...

  4. Cadmium exposure induces hematuria in Korean adults

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seung Seok [Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Kim, Myounghee, E-mail: dkkim73@gmail.com [Department of Dental Hygiene, College of Health Science, Eulji University, Gyeonggi-do 461-713 (Korea, Republic of); Lee, Su Mi [Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Lee, Jung Pyo [Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul 156-707 (Korea, Republic of); Kim, Sejoong [Department of Internal Medicine, Seoul National University Bundang Hospital, Gyeonggi-do 463-707 (Korea, Republic of); Joo, Kwon Wook [Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Lim, Chun Soo [Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul 156-707 (Korea, Republic of); Kim, Yon Su; Kim, Dong Ki [Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of)

    2013-07-15

    Introduction: Toxic heavy metals have adverse effects on human health. However, the risk of hematuria caused by heavy metal exposure has not been evaluated. Methods: Data from 4701 Korean adults were obtained in the Korean National Health and Nutritional Examination Survey (2008–2010). Blood levels of the toxic heavy metals cadmium, lead, and mercury were measured. Hematuria was defined as a result of ≥+1 on a urine dipstick test. The odds ratios (ORs) for hematuria were measured according to the blood heavy metal levels after adjusting for multiple variables. Results: Individuals with blood cadmium levels in the 3rd and 4th quartiles had a greater OR for hematuria than those in the 1st quartile group: 3rd quartile, 1.35 (1.019–1.777; P=0.037); 4th quartile, 1.52 (1.140–2.017; P=0.004). When blood cadmium was considered as a log-transformed continuous variable, the correlation between blood cadmium and hematuria was significant: OR, 1.97 (1.224–3.160; P{sub trend}=0.005). In contrast, no significant correlations between hematuria and blood lead or mercury were found in the multivariate analyses. Discussion: The present study shows that high cadmium exposure is associated with a risk of hematuria. -- Highlights: • A high level of blood cadmium is associated with a high risk of hematuria. • This correlation is independent of several confounding factors. • Blood levels of lead and mercury are not associated with risk of hematuria. • This is the first study on the correlation between cadmium exposure and hematuria risk.

  5. Hazards to wildlife from soil-borne cadmium reconsidered

    Science.gov (United States)

    Beyer, W.N.

    2000-01-01

    Cadmium is a toxic element that should be included in environmental risk assessments of contaminated soils. This paper argues, however, that hazards to wildlife from cadmium have often been overstated. The literature contains only meager evidence that wild animals have been seriously harmed by cadmium, even at severely contaminated sites. Although some researchers have reported that wildlife have accumulated concentrations of cadmium in their kidneys that were above suggested injury thresholds, the thresholds may be disputed, since they were well below the World Health Organization criterion of 200 mg/kg (wet weight) of cadmium in the renal cortex for protecting human health. Recent risk assessments have concluded that soil cadmium concentrations less than 1 mg/kg are toxic to soil organisms and wildlife, which implies that background concentrations of cadmium naturally found in soils are hazardous. An examination of the databases used to support these assessments suggested that the toxicity of cadmium has been exaggerated.

  6. Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

    OpenAIRE

    Kröger, H.

    2003-01-01

    We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

  7. Undocumented water column sink for cadmium in open ocean oxygen-deficient zones

    Science.gov (United States)

    Janssen, David J.; Conway, Tim M.; John, Seth G.; Christian, James R.; Kramer, Dennis I.; Pedersen, Tom F.; Cullen, Jay T.

    2014-01-01

    Cadmium (Cd) is a micronutrient and a tracer of biological productivity and circulation in the ocean. The correlation between dissolved Cd and the major algal nutrients in seawater has led to the use of Cd preserved in microfossils to constrain past ocean nutrient distributions. However, linking Cd to marine biological processes requires constraints on marine sources and sinks of Cd. Here, we show a decoupling between Cd and major nutrients within oxygen-deficient zones (ODZs) in both the Northeast Pacific and North Atlantic Oceans, which we attribute to Cd sulfide (CdS) precipitation in euxinic microenvironments around sinking biological particles. We find that dissolved Cd correlates well with dissolved phosphate in oxygenated waters, but is depleted compared with phosphate in ODZs. Additionally, suspended particles from the North Atlantic show high Cd content and light Cd stable isotope ratios within the ODZ, indicative of CdS precipitation. Globally, we calculate that CdS precipitation in ODZs is an important, and to our knowledge a previously undocumented marine sink of Cd. Our results suggest that water column oxygen depletion has a substantial impact on Cd biogeochemical cycling, impacting the global relationship between Cd and major nutrients and suggesting that Cd may be a previously unidentified tracer for water column oxygen deficiency on geological timescales. Similar depletions of copper and zinc in the Northeast Pacific indicate that sulfide precipitation in ODZs may also have an influence on the global distribution of other trace metals. PMID:24778239

  8. Hydrogen bonding in thiobenzamide synthon and its Cadmium complex: Crystal structure and Hirshfeld analysis

    Indian Academy of Sciences (India)

    INES RIGANE; SIWAR WALHA; ABDELHAMID BEN SALAH

    2016-09-01

    The thiobenzamid TBA and its Cd(II) complex, dichlorothiobenzamidecadmium(II) [Cd(TBA)Cl₂] complex has been synthesized and characterized by FT-IR, FT-Raman and UV–Vis spectroscopy. The crystal and molecular structure of TBA and [Cd(TBA)Cl₂] were determined by single crystal X-ray diffraction analysis. The molecular arrangement in the crystal structure of TBA can be described on the basis of supramolecular dimeric synthons built up by four independent TBA molecules stacked via N-H. . .S hydrogen bonds. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular interactions. The N-H. . .S hydrogen bond percentages were estimated to be 23.1%, 22.9%, 30.6% and 27.3% of Hirshfeld surfaces area respectively for each TBA molecule. Synthons are associated through C–H. . . π interactions at percentage of 33.8%, 38.2%, 24.3% and 19.4% to result in 3D network. The dichlorothiobenzamide cadmium(II) complex bonded by sulfur atom of thiobenzamide shows a double chain of distorted octahedra around the cadmium atoms running along the a axis and the packing is stabilized by intra- and inter-chain hydrogen bonding interactions of the type N–H. . .Cl and aromatic π. . .π stacking interactions between ring centroids at 21.8% and 7.6% of the Hirshfeld surface area, respectively. The decomposition of the complex to cadmium sulfide has been investigated by thermogravimetric analysis (TGA).

  9. Impact of Different Surface Ligands on the Optical Properties of PbS Quantum Dot Solids

    OpenAIRE

    Fan Xu; Luis Felipe Gerlein; Xin Ma; Chelsea R. Haughn; Doty, Matthew F.; Cloutier, Sylvain G.

    2015-01-01

    The engineering of quantum dot solids with low defect concentrations and efficient carrier transport through a ligand strategy is crucial to achieve efficient quantum dot (QD) optoelectronic devices. Here, we study the consequences of various surface ligand treatments on the light emission properties of PbS quantum dot films using 1,3-benzenedithiol (1,3-BDT), 1,2-ethanedithiol (EDT), mercaptocarboxylic acids (MPA) and ammonium sulfide ((NH4)2S). We first investigate the influence of differen...

  10. Modeling cadmium in the feed chain and cattle organs

    NARCIS (Netherlands)

    Fels-Klerx, van der H.J.; Romkens, P.F.A.M.; Franz, E.; Raamsdonk, van L.W.D.

    2011-01-01

    The objectives of this study were to estimate cadmium contamination levels in different scenarios related to soil characteristics and assumptions regarding cadmium accumulation in the animal tissues, using quantitative supply chain modeling. The model takes into account soil cadmium levels, soil pH,

  11. Epidemiological aspects of cadmium in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Piscator, M.

    1973-01-01

    Cadmium is highly toxic to man and it has an extremely long biological half-time. Under long-term low level exposure about one third of the total body burden is in the kidneys. In some European countries and USA mean renal cortical concentrations of cadmium 24-50 ppM wet weight at age 50 have been reported. In three areas in Japan the corresponding concentrations were 60 to 125 ppM wet weight. These normal concentrations have been thought to cause hypertension but so far epidemiological data are not available to support such a hypothesis. Renal tubular dysfunction may begin at a renal cortical concentration of about 200 ppM wet weight. In Japan extensive investigations have been carried out in several areas polluted by cadmium. Available data indicate that the prevalence of proteinuria is higher in the cadmium polluted areas and that the proteinuria is of the tubular type. Studies on dose-response relationships must include accurate and sensitive methods for the detection of low molecular weight proteinuria, which is an early sign in cadmium intoxication. 6 references, 1 table.

  12. Recycling of Spent Nickel-Cadmium Batteries

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A technique for recycling spent nickel-cadmium batteries, which makes separation of cadmium and nickel possible, is developed by laboratory-scale experiments. NH3-H2CO3 aqueous solution was used in this leaching technique. Since neutralization and/or solvent extraction were not required in the separation procedure of nickel and cadmium, the closed systemization of the process becomes possible. Experimental results show that, (1) if the NH3 concentration of leaching solution is sufficiently high and the ratio of H2CO3 to NH3 is properly adjusted, both Ni(OH)2 and Cd(OH)2 react with NH3 and quickly dissolve into leaching solution, and (2) Ni(OH)2 can be converted into insoluble NiO by calcination at 500€癈, and CdO from Cd(OH)2 by calcination maintains good solubility in NH3-H2CO3 aqueous solution. As a conclusion, the recycling technique characterized by two step leaching can be developed based on such changes in dissolution behavior by calcination. Meanwhile, the yields of 99.8% for nickel and 97.6% for cadmium are obtained, and the purities of recovered nickel and cadmium are 99.9% and 98.6%, respectively.

  13. Effect of anions on Toxicity of Cadmium Applied to MIcrobial Biomass in Red Soil

    Institute of Scientific and Technical Information of China (English)

    K.S.KHAN; XIEZHENGMIAO; 等

    1997-01-01

    A laboratory incubation experiment was conducted to elucidat the effects of associated anions on toxicity of cadmium applied to microbial biomass in the red soil. Cadmium was applied at six different levels,i.e.,O(background),5,15,30,60 and 100μg g-1 soil in the form of either cadmium acetate or cadmium chloride. Application of cadmium as cadmium acetate markedly reduced the soil microbial biomass carbon compared to cadmium applied as cadmium chlorde at all the tested levels.Similarly,organic carbon to biomass carbon ration in the soil was markedly increased by increasing the level of the cadmium in the soil as cadmium acetate,while the change wa much smaller in the case of cadmium chloride at the same cadmium levels.The results suggested that due consideration should be given to the source of cadmium while deciding the cadmium levles in experiments.

  14. Sulfide, the first inorganic substrate for human cells.

    Science.gov (United States)

    Goubern, Marc; Andriamihaja, Mireille; Nübel, Tobias; Blachier, François; Bouillaud, Frédéric

    2007-06-01

    Hydrogen sulfide (H2S) is produced inside the intestine and is known as a poison that inhibits cellular respiration at the level of cytochrome oxidase. However, sulfide is used as an energetic substrate by many photo- and chemoautotrophic bacteria and by animals such as the lugworm Arenicola marina. The concentrations of sulfide present in their habitats are comparable with those present in the human colon. Using permeabilized colonic cells to which sulfide was added by an infusion pump we show that the maximal respiratory rate of colonocyte mitochondria in presence of sulfide compares with that obtained with succinate or L-alpha-glycerophosphate. This oxidation is accompanied by mitochondrial energization. In contrast, other cell types not naturally exposed to high concentration of sulfide showed much lower oxidation rates. Mitochondria showed a very high affinity for sulfide that permits its use as an energetic substrate at low micromolar concentrations, hence, below the toxic level. However, if the supply of sulfide exceeds the oxidation rate, poisoning renders mitochondria inefficient and our data suggest that an anaerobic mechanism involving partial reversion of Krebs cycle already known in invertebrates takes place. In conclusion, this work provides additional and compelling evidence that sulfide is not only a toxic compound. According to our study, sulfide appears to be the first inorganic substrate for mammalian cells characterized thus far.

  15. The Evolution of Sulfide Tolerance in the Cyanobacteria

    Science.gov (United States)

    Miller, Scott R.; Bebout, Brad M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Understanding how the function of extant microorganisms has recorded both their evolutionary histories and their past interactions with the environment is a stated goal of astrobiology. We are taking a multidisciplinary approach to investigate the diversification of sulfide tolerance mechanisms in the cyanobacteria, which vary both in their degree of exposure to sulfide and in their capacity to tolerate this inhibitor of photosynthetic electron transport. Since conditions were very reducing during the first part of Earth's history and detrital sulfides have been found in Archean sediments, mechanisms conferring sulfide tolerance may have been important for the evolutionary success of the ancestors of extant cyanobacteria. Two tolerance mechanisms have been identified in this group: (1) resistance of photosystem II, the principal target of sulfide toxicity; and (2) maintenance of the ability to fix carbon despite photosystem II inhibition by utilizing sulfide as an electron donor in photosystem I - dependent, anoxygenic photosynthesis. We are presently collecting comparative data on aspects of sulfide physiology for laboratory clones isolated from a variety of habitats. These data will be analyzed within a phylogenetic framework inferred from molecular sequence data collected for these clones to test how frequently different mechanisms of tolerance have evolved and which tolerance mechanism evolved first. In addition, by analyzing these physiological data together with environmental sulfide data collected from our research sites using microelectrodes, we can also test whether the breadth of an organism's sulfide tolerance can be predicted from the magnitude of variation in environmental sulfide concentration it has experienced in its recent evolutionary past and whether greater average sulfide concentration and/or temporal variability in sulfide favors the evolution of a particular mechanism of sulfide tolerance.

  16. Investigating the distribution of dissolved copper, zinc, silver and cadmium in the Pacific Ocean

    Science.gov (United States)

    Janssen, D. J.; Cullen, J. T.

    2012-12-01

    A stated goal of the GEOTRACES program is to better understand the large-scale distribution of trace metals in the marine environment. A characteristic feature of the soft Lewis acid metals like copper (Cu), zinc (Zn), silver (Ag) and cadmium (Cd) is their correlation with the major algal nutrients. These correlations imply that the proximate control on the distribution of these metals is microbial uptake at the ocean surface, sinking associated with particulate organic matter and subsequent remineralization in the ocean interior. Combined with sedimentary records of past metal concentrations such correlations can provide much needed information on water mass circulation and nutrient cycling in the paleo-ocean. Today, as trace nutrients and/or toxins these metals help shape microbial community composition and influence productivity. Here we present depth profiles through the low dissolved oxygen waters of the north Pacific which show decoupling of trace metal-macronutrient relationships driven by depletion anomalies of trace metal concentrations in the broad, low oxygen layer. Similar anomalies have been previously reported in permanently anoxic layers (e.g. fjords) or in waters in contact with suboxic sediments and attributed to sulfidic removal of soft trace metals. The observed trace metal behavior and trace metal-macronutrient relationships in the oxygen minimum layer in the northeastern Pacific is consistent with the possibility of sulfidic scavenging of soft metals and the formation of insoluble metal sulfides in the water column. Implications of this influence on the basin scale distribution of soft metals like Cu, Zn, Ag, Cd through scavenging in the spreading low oxygen layer in the northeastern Pacific are discussed.

  17. A metal sulfide photocatalyst composed of ubiquitous elements for solar hydrogen production.

    Science.gov (United States)

    Shiga, Y; Umezawa, N; Srinivasan, N; Koyasu, S; Sakai, E; Miyauchi, M

    2016-06-14

    A visible-light-sensitive tin sulfide photocatalyst was designed based on a ubiquitous element strategy and density functional theory (DFT) calculations. Computational analysis suggested that tin monosulfide (SnS) would be more efficient than SnS2 as a photocathode for hydrogen production because of the low ionization potential and weak ionic character of SnS. To test this experimentally, nanoparticles of SnS were loaded onto a mesoporous electrode using a wet chemical method, and the bandgap of the synthesized SnS quantum dots was found to be tunable by adjusting the number of successive ionic layer adsorption and reaction (SILAR) cycles, which controls the magnitude of the quantum confinement effect. Efficient hydrogen production was achieved when the bandgap of SnS was wider than that of the bulk form.

  18. Speciation of arsenic in sulfidic waters

    Directory of Open Access Journals (Sweden)

    Ford Robert G

    2003-03-01

    Full Text Available Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH2S from 10-7.5 to 10-3.0 M, ΣAs from 10-5.6 to 10-4.8 M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH30, and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10-4.3 M at neutral pH. Conversion from neutral As(OH30 to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions.

  19. Iron-sulfide redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Guanguang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2016-06-14

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  20. Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2013-01-01

    A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts satisfact......A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts...... by the competition between chain‐branching and ‐propagating steps; modeling predictions are particularly sensitive to the branching fraction for the OCS + O reaction to form CO + SO or CO2 + S....

  1. Iron-sulfide redox flow batteries

    Science.gov (United States)

    Xia, Guan-Guang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2013-12-17

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  2. Reduction of Cadmium Uptake of Rice Plants Using Soil Amendments in High Cadmium Contaminated Soil: A Pot Experiment

    Directory of Open Access Journals (Sweden)

    Dian Siswanto

    2013-05-01

    Full Text Available The aims of this study were to investigate the effect of agricultural residues on reducing cadmium uptake in rice plants. The rice plants growing on no cadmium/free cadmium soils (N, Cd soils (Cds, and Cd soils each amended with 1% w/w of coir pith (CP, coir pith modified with sodium hydroxide (CPm and corncob (CC under high cadmium contaminated soil with an average 145 mg Cd kg-1 soil were investigated. The results showed that the cumulative transpiration of rice grown in various treatments under high cadmium contaminated soil followed the order: Cds > CPm ≥ CP ≥ CC. These transpirations directly influenced cadmium accumulation in shoots and husks of rice plants. The CC and CP seemed to work to reduce the cadmium uptake by rice plants indicated by accumulated cadmium in the husk that were 2.47 and 7.38 mg Cd kg-1 dry weight, respectively. Overall, transpiration tended to drive cadmium accumulation in plants for rice grown in high cadmium contaminated soil. The more that plants uptake cadmium, the lower cadmium that remains in the soil.

  3. Cadmium accumulation by Axonopus compressus (Sw. P. Beauv and Cyperus rotundas Linn growing in cadmium solution and cadmium-zinc contaminated soil

    Directory of Open Access Journals (Sweden)

    Paitip Thiravetyan

    2007-05-01

    Full Text Available This research investigated the phyto-remediation potentials of Cyperus rotundas Linn (Nutgrass and Axonopus compressus (Sw. P. Beauv (Carpetgrass for cadmium removal from cadmium solution andcadmium-zinc contaminated soil. Plants growth in the solution showed that cadmium decreased the relative growth rate of both grasses. However, the amount of cadmium accumulated in shoot and root was increasedwith the increase in cadmium concentration and exposure time. Growth in fertile soil mixed with Cd-contaminated zinc silicate residue (65% Si, 19% Ca, 2% Zn, 1% Mg and 0.03% Cd at the ratio of 50:50 (w/wfor 30 days showed that C. rotundas Linn accumulated cadmium in root and shoot to 2,178 and 1,144 mg kg-1 dry weight, respectively. A. compressus (Sw. P. Beauv accumulated cadmium in root and shoot to 1,965and 669 mg kg-1 dry weight, respectively. Scanning electron microscope connected to energy-dispersive X-ray spectroscopy suggested that the mechanism of cadmium accumulation by both grasses involved thecadmium precipitation in the stable form of cadmium silicate, which indicated that C. rotundas Linn and A. compressus (Sw. P. Beauv could be grown to prevent soil erosion and to remediate cadmium-contaminatedsoil.

  4. Subsurface heaters with low sulfidation rates

    Energy Technology Data Exchange (ETDEWEB)

    John, Randy Carl; Vinegar, Harold J

    2013-12-10

    A system for heating a hydrocarbon containing formation includes a heater having an elongated ferromagnetic metal heater section. The heater is located in an opening in a formation. The heater section is configured to heat the hydrocarbon containing formation. The exposed ferromagnetic metal has a sulfidation rate that goes down with increasing temperature of the heater, when the heater is in a selected temperature range.

  5. Hydrogen sulfide prodrugs—a review

    Directory of Open Access Journals (Sweden)

    Yueqin Zheng

    2015-09-01

    Full Text Available Hydrogen sulfide (H2S is recognized as one of three gasotransmitters together with nitric oxide (NO and carbon monoxide (CO. As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications.

  6. Hydrogen sulfide prodrugs—a review

    Science.gov (United States)

    Zheng, Yueqin; Ji, Xingyue; Ji, Kaili; Wang, Binghe

    2015-01-01

    Hydrogen sulfide (H2S) is recognized as one of three gasotransmitters together with nitric oxide (NO) and carbon monoxide (CO). As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications. PMID:26579468

  7. ELECTROKINETIC REMEDIATION STUDY FOR CADMIUM CONTAMINATED SOIL

    Directory of Open Access Journals (Sweden)

    P. Bala Ramudu

    2007-09-01

    Full Text Available This paper presents the results of an experimental research undertaken to evaluate different purging solutions to enhance the removal of cadmium from spiked contaminated field soil by electrokinetic remediation. Three experiments were conducted when soil was saturated with deionised water and subsequently deionised water, ammonium citrate and sodium citrate were used as purging solutions at anode end. One experiment was conducted when the soil was saturated with ammonium citrate and itself was used as the purging solution. Results showed that 49% reduction of cadmium concentration was achieved in the case of soil saturated (washed with ammonium citrate as well as purging solution also was ammonium citrate. The soil pH and washing solutions were the most important factors in controlling the removal of cadmium in electrokinetic remediation process.

  8. Redetermination of piperidinium hydrogen sulfide structure

    Science.gov (United States)

    Andras, Maria T.; Hepp, Aloysius F.; Fanwick, Phillip E.; Duraj, Stan A.; Gordon, Edward M.

    1994-01-01

    The presence of adventitious water in a reaction between dicyclopentamethylene thiuram-disulfide (C5H10NCS2)(sub 2) and a picoline solution of tricyclopentadienyl indium(III) (C5H5)(sub 3). It resulted in the formation of piperidinium hydrogen sulfide (C5H13NS). The piperidinium hydrogen sulfide produced in this way was unambiguously characterized by X-ray crystallography. The structure determination showed that the piperidinium hydrogen sulfide crystal (MW = 119.23 g/mol) has an orthorhombic (Pbcm) unit cell whose parameters are: a = 9.818(2), b = 7.3720(1), c = 9.754(1) A, V = 706.0(3) A(exp 3), Z=4. D(sub chi) = 1.122 g cm(exp -3), Mo K(alpha) (lamda = 0.71073), mu= 3.36 cm(exp -1), F(000) = 264.0, T =293 K, R = 0.036 for 343 reflections with F(sub O)(sup 2) greater than 3 sigma (F(sub O)(sup 2)) and 65 variables. The compound consists of (C5H10NH2)(+) cations and (SH)(-) anions with both species residing on crystallographic mirror planes. N-H -- S hydrogen bonding contributes to the interconnection of neighboring piperidinium components of the compound.

  9. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.;

    2004-01-01

    experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...... differences in KLaH2S at pH values between 4.5 and 8.0 became larger as the turbulence level increased, whereas those at pH between 4.5 and 7.0 did not statistically show any change. At constant pH, KLaH2S/KLaO2 was observed not to be dependent on the turbulence range studied. KLaH2S/KLaO2 ratio was 0...

  10. Quantum Blobs

    CERN Document Server

    de Gosson, Maurice A

    2011-01-01

    Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level sets defined by Fermi for the purpose of representing geometrically quantum states.

  11. Quantum Malware

    CERN Document Server

    Wu, L A; Wu, Lian-Ao; Lidar, Daniel

    2005-01-01

    Quantum computation and communication offer unprecedented advantages compared to classical information processing. Currently, quantum communication is moving from laboratory prototypes into real-life applications. When quantum communication networks become more widespread it is likely that they will be subject to attacks by hackers, virus makers, and other malicious intruders. Here we introduce the concept of "quantum malware" to describe such human-made intrusions. We offer a simple solution for storage of quantum information in a manner which protects quantum networks from quantum malware.

  12. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  13. Cadmium toxicity in the free-living nematode, Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Popham, J.D.; Webster, J.M.

    1979-10-01

    The effect of cadmium on the fecundity, growth, and fine structure of the free-living nematode Caenorhabditis elegans was studied. High concentrations of cadmium significantly decreased the fecundity and growth of these organisms. Electron microscopy showed that cadmium modifies the structure of the mitochondria in the esophagus and intestine, causes the formation of inclusion bodies in the nucleus of esophageal cells, and alters the morphology of cytosomes in the intestinal cells. The results suggest that the decreased fecundity and growth of cadmium-exposed C. elegans may be due to cadmium interfering with nutrient uptake or assimilation or both.

  14. Treatment of cadmium dust with two-stage leaching process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The treatment of cadmium dust with a two-stage leaching process was investigated to replace the existing sulphation roast-leaching processes. The process parameters in the first stage leaching were basically similar to the neutralleaching in zinc hydrometallurgy. The effects of process parameters in the second stage leaching on the extraction of zincand cadmium were mainly studied. The experimental results indicated that zinc and cadmium could be efficiently recoveredfrom the cadmium dust by two-stage leaching process. The extraction percentages of zinc and cadmium in two stage leach-ing reached 95% and 88% respectively under the optimum conditions. The total extraction percentage of Zn and Cdreached 94%.

  15. Sulfide scaling in low enthalpy geothermal environments; A survey

    Energy Technology Data Exchange (ETDEWEB)

    Criaud, A.; Fouillac, C. (Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France))

    1989-01-01

    A review of the sulfide scaling phenomena in low-temperature environments is presented. While high-temperature fluids tend to deposit metal sulfides because of their high concentrations of dissolved metals and variations of temperature, pressure and fluid chemistry, low temperature media are characterized by very low metal content but much higher dissolved sulfide. In the case of the goethermal wells of the Paris Basin, detailed studies demonstrate that the relatively large concentrations of chloride and dissolved sulfide are responsible for corrosion and consequent formation of iron sulfide scale composed of mackinawite, pyrite and pyrrhotite. The effects of the exploitation schemes are far less important than the corrosion of the casings. The low-enthalpy fluids that do not originate from sedimentary aquifers (such as in Iceland and Bulgaria), have a limited corrosion potential, and the thin sulfide film that appears may prevent the progress of corrosion.

  16. Oxidation and Precipitation of Sulfide in Sewer Networks

    DEFF Research Database (Denmark)

    Nielsen, A. H.

    calibrated and validated against field data. In the extension to the WATS model, sulfur transformations were described by six processes: 1. Sulfide production taking place in the biofilm and sediments covering the permanently wetted sewer walls; 2. Biological sulfide oxidation in the permanently wetted...... on oxidation and precipitation of sulfide, which are considered important processes in the sulfur cycle in wastewater and biofilms of sewer networks. Based on experimental studies, it was the objective to establish kinetics and stoichiometry of oxidation and precipitation of sulfide and to integrate...... the processes in an already existing sewer process model, thereby improving its capabilities for prediction of sulfide buildup in wastewater and atmosphere of sewer networks. Accordingly, efforts were made to develop experimental procedures for estimation of model parameters. Sulfide oxidation in both...

  17. Organization of the human mitochondrial hydrogen sulfide oxidation pathway.

    Science.gov (United States)

    Libiad, Marouane; Yadav, Pramod Kumar; Vitvitsky, Victor; Martinov, Michael; Banerjee, Ruma

    2014-11-07

    Sulfide oxidation is expected to play an important role in cellular switching between low steady-state intracellular hydrogen sulfide levels and the higher concentrations where the physiological effects are elicited. Yet despite its significance, fundamental questions regarding how the sulfide oxidation pathway is wired remain unanswered, and competing proposals exist that diverge at the very first step catalyzed by sulfide quinone oxidoreductase (SQR). We demonstrate that, in addition to sulfite, glutathione functions as a persulfide acceptor for human SQR and that rhodanese preferentially synthesizes rather than utilizes thiosulfate. The kinetic behavior of these enzymes provides compelling evidence for the flow of sulfide via SQR to glutathione persulfide, which is then partitioned to thiosulfate or sulfite. Kinetic simulations at physiologically relevant metabolite concentrations provide additional support for the organizational logic of the sulfide oxidation pathway in which glutathione persulfide is the first intermediate formed.

  18. Environmental cadmium and breast cancer risk

    OpenAIRE

    2010-01-01

    Breast cancer is the most prevalent women's cancer, with an age-adjusted incidence of 122.9 per 100,000 US women. Cadmium, a ubiquitous carcinogenic pollutant with multiple biological effects, has been reported to be associated with breast cancer in one US regional case-control study. We examined the association of breast cancer with urinary cadmium (UCd), in a case-control sample of women living on Long Island (LI), NY (100 with breast cancer and 98 without), a region with an especially high...

  19. Quantum cloning

    OpenAIRE

    Scarani, Valerio; Iblisdir, Sofyan; Gisin, Nicolas; Acin, Antonio

    2005-01-01

    The impossibility of perfectly copying (or cloning) an arbitrary quantum state is one of the basic rules governing the physics of quantum systems. The processes that perform the optimal approximate cloning have been found in many cases. These "quantum cloning machines" are important tools for studying a wide variety of tasks, e.g. state estimation and eavesdropping on quantum cryptography. This paper provides a comprehensive review of quantum cloning machines (both for discrete-dimensional an...

  20. Measurement of plasma hydrogen sulfide in vivo and in vitro

    OpenAIRE

    Shen, Xinggui; Pattillo, Christopher B.; Pardue, Sibile; Bir, Shyamal C.; Wang, Rui; Kevil, Christopher G.

    2011-01-01

    The gasotransmitter hydrogen sulfide is known to regulate multiple cellular functions during normal and pathophysiological states. However, a paucity of concise information exists regarding quantitative amounts of hydrogen sulfide involved in physiological and pathological responses. This is primarily due to disagreement among various methods employed to measure free hydrogen sulfide. In this article, we describe a very sensitive method of measuring the presence of H2S in plasma down to nanom...

  1. Cadmium Exposure and Pancreatic Cancer in South Louisiana

    Directory of Open Access Journals (Sweden)

    Brian G. Luckett

    2012-01-01

    Full Text Available Cadmium has been hypothesized to be a pancreatic carcinogen. We test the hypothesis that cadmium exposure is a risk factor for pancreatic cancer with a population-based case-control study sampled from a population with persistently high rates of pancreatic cancer (south Louisiana. We tested potential dietary and nondietary sources of cadmium for their association with urinary cadmium concentrations which reflect long-term exposure to cadmium due to the accumulation of cadmium in the kidney cortex. Increasing urinary cadmium concentrations were significantly associated with an increasing risk of pancreatic cancer (2nd quartile OR = 3.34, 3rd = 5.58, 4th = 7.70; test for trend P≤0.0001. Potential sources of cadmium exposure, as documented in the scientific literature, found to be statistically significantly associated with increased risk of pancreatic cancer included working as a plumber, pipefitter or welder (OR = 5.88 and high consumption levels of red meat (4th quartile OR = 6.18 and grains (4th quartile OR = 3.38. Current cigarette smoking, at least 80 pack years of smoking, occupational exposure to cadmium and paints, working in a shipyard, and high consumption of grains were found to be statistically significantly associated with increased concentrations of urinary cadmium. This study provides epidemiologic evidence that cadmium is a potential human pancreatic carcinogen.

  2. Cadmium-induced cancers in animals and in humans.

    Science.gov (United States)

    Huff, James; Lunn, Ruth M; Waalkes, Michael P; Tomatis, Lorenzo; Infante, Peter F

    2007-01-01

    Discovered in the early 1800s, the use of cadmium and various cadmium salts started to become industrially important near the close of the 19th century, rapidly thereafter began to flourish, yet has diminished more recently. Most cadmium used in the United States is a byproduct from the smelting of zinc, lead, or copper ores, and is used to manufacture batteries. Carcinogenic activity of cadmium was discovered first in animals and only subsequently in humans. Cadmium and cadmium compounds have been classified as known human carcinogens by the International Agency for Research on Cancer and the National Toxicology Program based on epidemiologic studies showing a causal association with lung cancer, and possibly prostate cancer, and studies in experimental animals, demonstrating that cadmium causes tumors at multiple tissue sites, by various routes of exposure, and in several species and strains. Epidemiologic studies published since these evaluations suggest that cadmium is also associated with cancers of the breast, kidney, pancreas, and urinary bladder. The basic metal cationic portion of cadmium is responsible for both toxic and carcinogenic activity, and the mechanism of carcinogenicity appears to be multifactorial. Available information about the carcinogenicity of cadmium and cadmium compounds is reviewed, evaluated, and discussed.

  3. Quantum Computer Games: Quantum Minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  4. Quantum CPU and Quantum Algorithm

    OpenAIRE

    Wang, An Min

    1999-01-01

    Making use of an universal quantum network -- QCPU proposed by me\\upcite{My1}, it is obtained that the whole quantum network which can implement some the known quantum algorithms including Deutsch algorithm, quantum Fourier transformation, Shor's algorithm and Grover's algorithm.

  5. Study of cadmium electrochemical deposition in sulfate medium

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, T.; Solorza, O.; Sanchez, H.

    2000-03-01

    The cadmium electrochemical deposition process from sulfate medium was studied by means of different electrochemical techniques in both stationary and nonstationary diffusion regimes. The kinetics of the electrochemical reduction of cadmium on solid cadmium electrodes was examined and the kinetic parameters are presented, as well as the diffusion coefficient derived from the different techniques. Temperature has an important effect on the cadmium reduction kinetics, and the activation energy of the process was evaluated. The electrochemical deposition of cadmium is a complex process due to the coexistence of adsorption and nucleation processes; the adsorbed electroactive species appears to be Cd{sup +2}, and a mechanism for cadmium electrodeposition on solid cadmium electrodes is proposed.

  6. Murine strain differences and the effects of zinc on cadmium concentrations in tissues after acute cadmium exposure

    Energy Technology Data Exchange (ETDEWEB)

    King, L.M. [ARS USDA, Germplasm and Gamete Physiology Lab., Beltsville, MD (United States); Anderson, M.B. [Dept. of Anatomy, Tulane Univ. School of Medicine, New Orleans, LA (United States); Sikka, S.C. [Dept. of Urology, Tulane Univ. School of Medicine, New Orleans, LA (United States); George, W.J. [Dept. of Pharmacology, Tulane Univ. School of Medicine, New Orleans, LA (United States)

    1998-10-01

    The role of strain differences in cadmium tissue distribution was studied using sensitive (129/J) and resistant (A/J) mice. These murine strains have previously been shown to differ in their susceptibility to cadmium-induced testicular toxicity. Cadmium concentration was measured in testis, epididymis, seminal vesicle, liver, and kidney at 24 h after cadmium chloride exposure (4, 10, and 20 {mu}mol/kg CdCl{sub 2}). The 129/J mice exhibited a significant increase in cadmium concentration in testis, epididymis, and seminal vesicle at all cadmium doses used, compared to A/J mice. However, cadmium concentrations in liver and kidney were not different between the strains, at any dose, indicating that cadmium uptake is similar in these organs at 24 h. These murine strains demonstrate similar hepatic and renal cadmium uptake but significantly different cadmium accumulation in the reproductive organs at 24 h. The mechanism of the protective effect of zinc on cadmium toxicity was studied by assessing the impact of zinc acetate (ZnAc) treatment on cadmium concentrations in 129/J mice after 24 h. Zinc pretreatment (250 {mu}mol/kg ZnAc), given 24 h prior to 20 {mu}mol/kg CdCl{sub 2} administration, significantly decreased the amount of cadmium in the testis, epididymis, and seminal vesicle of 129/J mice, and significantly increased the cadmium content of the liver after 24 h. Cadmium levels in the kidney were unaffected at this time. Zinc pretreatment also prevented the cadmium-induced decrease in testicular sperm concentration and epididymal sperm motility seen in 129/J mice. These findings suggest that the differences in the two murine strains may be attributed partly to the differential accumulation of cadmium in murine gonads. This may be caused by strain differences in the specificity of cadmium transport mechanisms. The protective role of zinc in cadmium-induced testicular toxicity in the sensitive strain may be due to an interference in the cadmium uptake by susceptible

  7. Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy.

    Science.gov (United States)

    Song, Kai; Wang, Fen; Li, Qian; Shi, Yong-Bing; Zheng, Hui-Fen; Peng, Hanjing; Shen, Hua-Ying; Liu, Chun-Feng; Hu, Li-Fang

    2014-06-01

    Hydrogen sulfide has recently been found decreased in chronic kidney disease. Here we determined the effect and underlying mechanisms of hydrogen sulfide on a rat model of unilateral ureteral obstruction. Compared with normal rats, obstructive injury decreased the plasma hydrogen sulfide level. Cystathionine-β-synthase, a hydrogen sulfide-producing enzyme, was dramatically reduced in the ureteral obstructed kidney, but another enzyme cystathionine-γ-lyase was increased. A hydrogen sulfide donor (sodium hydrogen sulfide) inhibited renal fibrosis by attenuating the production of collagen, extracellular matrix, and the expression of α-smooth muscle actin. Meanwhile, the infiltration of macrophages and the expression of inflammatory cytokines including interleukin-1β, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in the kidney were also decreased. In cultured kidney fibroblasts, a hydrogen sulfide donor inhibited the cell proliferation by reducing DNA synthesis and downregulating the expressions of proliferation-related proteins including proliferating cell nuclear antigen and c-Myc. Further, the hydrogen sulfide donor blocked the differentiation of quiescent renal fibroblasts to myofibroblasts by inhibiting the transforming growth factor-β1-Smad and mitogen-activated protein kinase signaling pathways. Thus, low doses of hydrogen sulfide or its releasing compounds may have therapeutic potentials in treating chronic kidney disease.

  8. Limitation of Sulfide Capacity Concept for Molten Slags

    Science.gov (United States)

    Jung, In-Ho; Moosavi-Khoonsari, Elmira

    2016-04-01

    The sulfide capacity concept has been widely used in pyrometallurgy to define sulfur removal capacities of slags. Typically, the sulfide capacity is considered to be a unique slag property depending only on temperature regardless of partial pressures of oxygen and sulfur. In the present study, it is demonstrated that sulfide capacities of slags in particular those of Na2O-containing slags can vary with partial pressures of oxygen and sulfur due to large solubility of sulfide in Na2O-containing slag systems.

  9. Influence of iron on sulfide inhibition in dark biohydrogen fermentation.

    Science.gov (United States)

    Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Nakhla, George

    2012-12-01

    Sulfide impact on biohydrogen production using dark fermentation of glucose at 37 °C was investigated. Dissolved sulfide (S(2-)) at a low concentration (25mg/L) increased biohydrogen production by 54% relative to the control (without iron addition). Whereas on initial dissolved S(2-) concentration of 500 mg/L significantly inhibited the biohydrogen production with total cumulative biohydrogen decreasing by 90% compared to the control (without iron addition). At sulfide concentrations of 500 mg S(2-)/L, addition of Fe(2+) at 3-4 times the theoretical requirement to precipitate 100% of the dissolved S(2-) entirely eliminated the inhibitory effect of sulfide.

  10. MEASURING METAL SULFIDE COMPLEXES IN OXIC RIVER WATERS WITH SQUARE WAVE VOLTAMMETRY. (R825395)

    Science.gov (United States)

    A sulfide identification protocol was developed to quantify specific metal sulfides that could exist in river water. Using a series of acid additions, nitrogen purges, and voltammetric analyses, metal sulfides were identified and semiquantified in three specific gr...

  11. Urinary cadmium and estimated dietary cadmium in the Women's Health Initiative.

    Science.gov (United States)

    Quraishi, Sabah M; Adams, Scott V; Shafer, Martin; Meliker, Jaymie R; Li, Wenjun; Luo, Juhua; Neuhouser, Marian L; Newcomb, Polly A

    2016-01-01

    Cadmium, a heavy metal dispersed in the environment as a result of industrial and agricultural applications, has been implicated in several human diseases including renal disease, cancers, and compromised bone health. In the general population, the predominant sources of cadmium exposure are tobacco and diet. Urinary cadmium (uCd) reflects long-term exposure and has been frequently used to assess cadmium exposure in epidemiological studies; estimated dietary intake of cadmium (dCd) has also been used in several studies. The validity of dCd in comparison with uCd is unclear. This study aimed to compare dCd, estimated from food frequency questionnaires, to uCd measured in spot urine samples from 1,002 participants of the Women's Health Initiative. Using linear regression, we found that dCd was not statistically significantly associated with uCd (β=0.006, P-value=0.14). When stratified by smoking status, dCd was not significantly associated with uCd both in never smokers (β=0.006, P-value=0.09) and in ever smokers (β=0.003, P-value=0.67). Our results suggest that because of the lack of association between estimated dCd and measured uCd, dietary estimation of cadmium exposure should be used with caution in epidemiologic studies.

  12. Quantum memristors

    Science.gov (United States)

    Pfeiffer, P.; Egusquiza, I. L.; di Ventra, M.; Sanz, M.; Solano, E.

    2016-07-01

    Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.

  13. RISK ASSESSMENT FOR CADMIUM IN PHOSPHATE FERTILIZERS

    Science.gov (United States)

    Cadmium induced renal tubular dysfunction occurred where subsistence rice farmers produced their lifetime dietary rice on Zn-mine waste contaminated soils in Japan and other Asian countries. Research has shown that polished rice Cd is greatly increased while grain Zn is not incre...

  14. Field scale behaviour of cadmium in soil.

    NARCIS (Netherlands)

    Boekhold, A.E.

    1992-01-01

    Although total heavy metal contents of soil are often used to express the degree of contamination, they are of little value to judge environmental effects. The main objective of this thesis was to develop and test methodologies with which environmental risks of cadmium pollution of field soils can b

  15. Koper, zink en cadmium in voeding

    NARCIS (Netherlands)

    Smolders, E.A.A.

    2003-01-01

    In een tabel is aangegeven hoeveel koper, zink en cadmium een rantsoen gemiddeld moet bevatten om de behoefte van melkvee te dekken. Daarbij is uitgegaan van een gemiddelde benutting. De vraag is of er bij een tekort aangevuld moet worden en of er bij een teveel weggelaten moet worden.

  16. Mobiliteit van cadmium in de bodem

    NARCIS (Netherlands)

    Chardon, W.J.

    1984-01-01

    The adsorption of cadmium by twelve Dutch soils was investigated under widely varying circumstances. The adsorption can be described with the Freundlich equation; the parameters of this equation can be predicted using the properties of the soil (pH, organic carbon and clay content).The adsorption ap

  17. Toxicological analysis of 17 autopsy cases of hydrogen sulfide poisoning resulting from the inhalation of intentionally generated hydrogen sulfide gas.

    Science.gov (United States)

    Maebashi, Kyoko; Iwadate, Kimiharu; Sakai, Kentaro; Takatsu, Akihiro; Fukui, Kenji; Aoyagi, Miwako; Ochiai, Eriko; Nagai, Tomonori

    2011-04-15

    Although many cases of fatal hydrogen sulfide poisoning have been reported, in most of these cases, it resulted from the accidental inhalation of hydrogen sulfide gas. In recent years, we experienced 17 autopsy cases of fatal hydrogen sulfide poisoning due to the inhalation of intentionally generated hydrogen sulfide gas. In this study, the concentrations of sulfide and thiosulfate in blood, urine, cerebrospinal fluid and pleural effusion were examined using GC/MS. The sulfide concentrations were blood: 0.11-31.84, urine: 0.01-1.28, cerebrospinal fluid: 0.02-1.59 and pleural effusion: 2.00-8.59 (μg/ml), while the thiosulfate concentrations were blood: 0-0.648, urine: 0-2.669, cerebrospinal fluid: 0.004-0.314 and pleural effusion: 0.019-0.140 (μmol/ml). In previous reports, the blood concentration of thiosulfate was said to be higher than that of sulfide in hydrogen sulfide poisoning cases, although the latter was higher than the former in 8 of the 14 cases examined in this study. These results are believed to be strongly influenced by the atmospheric concentration of hydrogen sulfide the victims were exposed to and the time interval between exposure and death.

  18. Quantum trajectories

    CERN Document Server

    Chattaraj, Pratim Kumar

    2010-01-01

    The application of quantum mechanics to many-particle systems has been an active area of research in recent years as researchers have looked for ways to tackle difficult problems in this area. The quantum trajectory method provides an efficient computational technique for solving both stationary and time-evolving states, encompassing a large area of quantum mechanics. Quantum Trajectories brings the expertise of an international panel of experts who focus on the epistemological significance of quantum mechanics through the quantum theory of motion.Emphasizing a classical interpretation of quan

  19. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco.

    Science.gov (United States)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild; Nielsen, Asbjørn Haaning

    2015-11-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit with some uncertainty. It was concluded that the model could be applied for the purpose in mind.

  20. Lead and cadmium in breast milk

    Energy Technology Data Exchange (ETDEWEB)

    Sternowsky, H.J.; Wessolowski, R.

    1985-04-01

    Breast milk from 10 women each from the city of Hamburg and from a rural area was analyzed by atomic absorption spectrometry for contamination with lead and cadmium. Samples were examined at regular intervals for 3 months after birth. On day 5 a diurnal profile was analyzed; on the other days milk was taken before and after the morning feed. For breast milk as the main source of nutrition in infants, this study shows values of 9.1 +- 2.5 (SD) ..mu..g/l for lead in the rural population, with a tendency to decrease towards the end of lactation. Urban mothers had 13.3 +- 5.5 (SD) ..mu..g/l, with a tendency to increase. Mean cadmium content in rural mothers was 17.3 +- 4.9 ..mu..g/l, with much higher values in the colostrum and a decrease after 15 days. Urban mothers had 24.6 +- 7.3 ..mu..g/l, again with high colostrum values and a subsequent decrease. Calculated daily intake according to these values is presented, based on 840 ml breast milk for a 5.5 kg infant per day. Rural infants ingested 0.9-1.3 ..mu..g/kg/day of lead, and in the city 1.5-2.3 ..mu..g/kg/day. Cadmium intake in rural infants amounted from 1.2-1.8 ..mu..g/kg/day; in Hamburg it was 1.6-2.2 ..mu..g/kg/day. Thus the daily ingestion of lead was just below the DPI, cadmium ingestion was higher than the DPI for adults. The rural population had lower values in breast milk for both heavy metals than the urban population, although not statistically significant. Compared to earlier reports there was a slight increase in lead concentration and a more significant increase for cadmium.

  1. Cadmium and Chrome Concentrations in Human Milk

    Directory of Open Access Journals (Sweden)

    Sima Nazarpour

    2014-04-01

    Full Text Available Introduction: Nutrition of children has the highest priority in any program aimed at children's health care. Milk contaminated with various toxic elements can have adverse effects on children's health. This study aimed to determine the concentration of heavy metals including cadmium(Cd and chromium (Cr of breast feeding women’s milk in Varamin. Methods: This is a cross sectional study. In the present study, chromium and cadmium levels in milk of 100 mothers attending clinics in the city of Varamin were measured in four to eight weeks after delivery, using atomic absorption spectrometry. Results: The mean values (±SD of Cd and Cr in human milk were 5±6.9 μg/ml and 3±2.7 μg/ml respectively. Result of Linear regression showed that cadmium levels were higher in breast milk of people living close to the factory or industrial center. Also, the chromium levels were higher in the breast milk of women in cases of: Smoking by spouses, consumption of imported rice, consumption of mineral water, and living close to the factory or an industrial center. Conclusion: This study showed that the relationship of some factors such as living near a factory or an industrial center, smoking by spouse, the type of consumed rice and water, with the level of cadmium and chromium. Cadmium and chromium levels of breast milk in this study were higher than the levels of these elements mentioned in the reviewed articles and international standard. Because some variables, such as living near a factory or an industrial center, smoking by spouse, the type of consumed rice and water can affect the amount of entering elements in breast milk. Actions can be taken to reduce or eliminate these variables in order to decrease the mentioned elements in human milk.

  2. Cadmium phytoextraction potential of different Alyssum species

    Energy Technology Data Exchange (ETDEWEB)

    Barzanti, R., E-mail: rbarzanti@supereva.it [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Colzi, I., E-mail: ilariacolzi@hotmail.it [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Arnetoli, M., E-mail: miluscia@gmail.com [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Gallo, A., E-mail: galloalessia@hotmail.com [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Pignattelli, S., E-mail: sara.pignattelli@gmail.com [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Gabbrielli, R., E-mail: gabbrielli@unifi.it [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy); Gonnelli, C., E-mail: cristina.gonnelli@unifi.it [Department of Evolutionary Biology, Universita di Firenze, via Micheli 1, 50121 Firenze (Italy)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer The possibility of using serpentine plants for phytoextraction of Cd was investigated. Black-Right-Pointing-Pointer Variation in Cd tolerance, accumulation and translocation in three Alyssum plants with different phenotypes were found. Black-Right-Pointing-Pointer Alyssum montanum showed higher Cd tolerance and accumulation than the Ni hyperaccumulator Alyssum bertolonii. Black-Right-Pointing-Pointer As for the kinetic parameters of the Cd uptake system, A. montanum presented a low apparent K{sub m} value. Black-Right-Pointing-Pointer The V{sub max} values were not significantly different among the plants. - Abstract: This work was planned for providing useful information about the possibility of using serpentine adapted plants for phytoextraction of cadmium, element scarcely represented in such metalliferous environment. To this aim, we investigated variation in cadmium tolerance, accumulation and translocation in three Alyssum plants with different phenotypes: Alyssum bertolonii, that is a serpentine endemic nickel hyperaccumulator, and two populations of Alyssum montanum, one adapted and one not adapted to serpentine soils. Plants were hydroponically cultivated in presence of increasing concentrations of CdSO{sub 4} for two weeks. For the metal concentration used in the experiments, the three different Alyssum populations showed variation in cadmium tolerance, accumulation and content. The serpentine adapted population of A. montanum showed statistically higher cadmium tolerance and accumulation than A. bertolonii and the population of A. montanum not adapted to serpentine soil thus deserving to be investigated for phytoextraction purposes. Furthermore, as for the kinetic parameters of the cadmium uptake system, A. montanum serpentine population presented a low apparent K{sub m} value, suggesting a high affinity for this metal of its uptake system, whereas the V{sub max} values were not significantly different among the

  3. Modelling of Cadmium Transport in Soil-Crop System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A model for simulating cadmium transport in a soil-plant system was built using a commercial simu lating program named Powersim on the basis of input-output processes happening in the soil-plant system.Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52 ug m-2 under initial soil cadmium concentrations to 65 μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.

  4. Accumulation of cadmium in livers and kidneys in Greenlanders

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, Poul [National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)]. E-mail: poj@dmu.dk; Mulvad, Gert [Primary Health Care Center, DK-3900 Nuuk, Greenland (Denmark); Centre for Arctic Environmental Medicine, University of Aarhus, Universitetsparken, DK-8000 Aarhus C (Denmark); Pedersen, Henning Sloth [Primary Health Care Center, DK-3900 Nuuk, Greenland (Denmark); Centre for Arctic Environmental Medicine, University of Aarhus, Universitetsparken, DK-8000 Aarhus C (Denmark); Hansen, Jens C. [Centre for Arctic Environmental Medicine, University of Aarhus, Universitetsparken, DK-8000 Aarhus C (Denmark); Riget, Frank [National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)

    2006-12-15

    In the Arctic, the traditional diet exposes its people to a very high intake of cadmium because it is highly concentrated in the liver and kidneys of commonly eaten marine mammals. In one study in Greenland, the cadmium intake was estimated to 182 {mu}g/day/person in the fall and 346 in the spring. To determine whether the cadmium is accumulated in humans, we analyzed autopsy samples of liver and kidneys from 95 ethnic Greenlanders (aged 19-89) who died from a wide range of causes. The cadmium concentration in liver (overall mean 1.97 {mu}g/g wet wt) appeared to be unrelated to any particular age group, whereas the concentrations in the kidneys peaked in Greenlanders between 40 and 50 years of age (peak concentration 22.3 {mu}g/g wet wt). Despite the high cadmium levels in the typical Greenlander diet, we found that the cadmium concentrations in livers and kidneys were comparable to those reported from Denmark, Sweden, Australia and Great Britain. Furthermore, even though the mean cadmium intake from the diet was estimated to be 13-25 times higher in Greenlanders than in Danes, we found similar cadmium levels in the kidneys of both. Seal livers and kidneys are the main source of cadmium in the diet of Greenlanders, but these tissues are not eaten in Denmark. Thus, our results suggest that the accumulation of cadmium from Greenlander's marine diet is very low.

  5. Hepatoprotective activity of Moringa oleifera against cadmium toxicity in rats

    Directory of Open Access Journals (Sweden)

    Reetu Toppo

    2015-04-01

    Full Text Available Aim: The present investigation has been conducted to evaluate the hepatoprotective activity of Moringa oleifera against cadmium-induced toxicity in rats. Materials and Methods: For this study, 18 Wistar albino rats were taken. Control group, Group I rats were given cadmium chloride @ 200 ppm per kg and Group II rats were treated with M. oleifera extract @ 500 mg/kg along with cadmium chloride @ 200 ppm per kg (daily oral for 28 days. On 29th day, animals were slaughtered and various parameters were determined. Serum biomarkers, oxidative stress parameters, histomorphological examination were carried out with estimation of cadmium concentration in liver tissues. Results: Oral administration of cadmium chloride @ 200 ppm/kg for 28 days resulted in a significant increase in aspartate aminotransferase (AST, alanine transaminase (ALT, alkaline phosphatase (ALP, significant (p≤0.01 increase of lipid peroxidation (LPO and decrease in superoxide dismutase (SOD, and increase in cadmium accumulation in liver. Treatment with M. oleifera @ 500 mg/kg significantly (p<0.01 decreased the elevated ALP, AST, ALT, LPO levels and increase in SOD levels, and as compared to cadmium chloride treated group. However, there was no significant difference in cadmium concentration in liver when compared with cadmium chloride treated group. Conclusion: The study conclude that supplementation of M. oleifera (500 mg/kg, daily oral for 28 days has shown protection against cadmium-induced hepatotoxicity.

  6. Mercury Sulfide Dimorphism in Thioarsenate Glasses

    OpenAIRE

    KASSEM, Mohammad; Sokolov, Anton; Cuisset, Arnaud,; Usuki, Takeshi; Khaoulani, Sohayb; Masselin, Pascal; Le Coq, David,; Feygenson, M.; Benmore, C. J.; Hannon, Alex,; Neuefeind, J. C.; Bychkov, Eugene

    2016-01-01

    International audience; Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding pattern are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity o...

  7. 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.

  8. Quantum robots and quantum computers

    Energy Technology Data Exchange (ETDEWEB)

    Benioff, P.

    1998-07-01

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  9. Quantum Darwinism

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H [Los Alamos National Laboratory

    2008-01-01

    Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.

  10. Quantum music

    CERN Document Server

    Putz, Volkmar

    2015-01-01

    We consider ways of conceptualizing, rendering and perceiving quantum music, and quantum art in general. Thereby we give particular emphasis to its non-classical aspects, such as coherent superposition and entanglement.

  11. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    Science.gov (United States)

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  12. Recent findings on sinks for sulfide in gravity sewer networks

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2006-01-01

    summarizes this newly obtained knowledge and emphasizes important implications of the findings. Model simulations of the in-sewer processes important for the sulfur cycle showed that sulfide oxidation in the wetted biofilm is typically the most important sink for dissolved sulfide in gravity sewers. However...

  13. Hydrogen sulfide: physiological properties and therapeutic potential in ischaemia.

    Science.gov (United States)

    Bos, Eelke M; van Goor, Harry; Joles, Jaap A; Whiteman, Matthew; Leuvenink, Henri G D

    2015-03-01

    Hydrogen sulfide (H2 S) has become a molecule of high interest in recent years, and it is now recognized as the third gasotransmitter in addition to nitric oxide and carbon monoxide. In this review, we discuss the recent literature on the physiology of endogenous and exogenous H2 S, focusing upon the protective effects of hydrogen sulfide in models of hypoxia and ischaemia.

  14. Quantum Abacus

    CERN Document Server

    Cheon, T

    2004-01-01

    We show that the U(2) family of point interactions on a line can be utilized to provide the U(2) family of qubit operations for quantum information processing. Qubits are realized as localized states in either side of the point interaction which represents a controllable gate. The manipulation of qubits proceeds in a manner analogous to the operation of an abacus. Keywords: quantum computation, quantum contact interaction, quantum wire

  15. Quantum Econophysics

    OpenAIRE

    Esteban Guevara

    2006-01-01

    The relationships between game theory and quantum mechanics let us propose certain quantization relationships through which we could describe and understand not only quantum but also classical, evolutionary and the biological systems that were described before through the replicator dynamics. Quantum mechanics could be used to explain more correctly biological and economical processes and even it could encloses theories like games and evolutionary dynamics. This could make quantum mechanics a...

  16. Quantum Nanomechanics

    OpenAIRE

    2008-01-01

    Quantum Nanomechanics is the emerging field which pertains to the mechanical behavior of nanoscale systems in the quantum domain. Unlike the conventional studies of vibration of molecules and phonons in solids, quantum nanomechanics is defined as the quantum behavior of the entire mechanical structure, including all of its constituents--the atoms, the molecules, the ions, the electrons as well as other excitations. The relevant degrees of freedom of the system are described by macroscopic var...

  17. Cadmium sulfide/copper sulfide heterojunction cell research by sputter deposition. Quarterly technical progress report, March 1, 1981-June 30, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, J.A.; Anderson, W.W.; Meakin, J.D.

    1981-08-01

    A second series of hybrid cells with sputter-deposited Cu/sub 2/S layers has been fabricated. An efficiency of about 4 3/4%, without antireflection coating, was achieved for one of the cells. This result approaches the 5 3/4% which was achieved in the first set (different Cu/sub 2/S deposition conditions) and confirms the viability of the sputtering process for this application. Significant progress has been made in fabricating all-sputtered cells with CdS layers deposited by planar magnetron reactive sputtering. Efficiencies of approximately 3%, without antireflection coatings, have been achieved in the as-deposited state for seven cells. Individual cells have yielded a J/sub sc/ of 12 mA/cm/sup 2/, a V/sub oc/ of 0.53V, and a fill factor of 0.72. Taken together these parameters would yield an efficiency of 4 1/2%. A strong coupling is found between the properties of the Cu/sub 2/S and CdS layers. However, the conditions which maximize J/sub sc/, V/sub oc/ and the fill factor do not appear to be mutually exclusive. Reflectance measurements indicate that 30% or more of the incident radiation is being reflected from the front surface of the cells over the wavelength range of the solar spectrum. Thus optimization of the cell parameters with a suitable antireflection coating should yield cell efficiencies of about 6%. Characterization of the junctions formed in the all-sputtered cells under near-optimum deposition conditions indicates that they have remarkable properties in their as-deposited state, being very similar to high performance conventional cells after heat treatment. Junction ideality factors are about unity in the light, with J/sub 0/ values of about 2 x 10/sup -8/ mA/cm/sup 2/. Interface recombination velocities are as low as a few times 10/sup 5/ cm/sec. CdS depletion layer widths are about 2000 nm in the dark and collapse to about 200 nm under illumination.

  18. Quantum cryptography

    NARCIS (Netherlands)

    Fehr, S.

    2010-01-01

    Quantum cryptography makes use of the quantum-mechanical behavior of nature for the design and analysis of cryptographic schemes. Optimally (but not always), quantum cryptography allows for the design of cryptographic schemes whose security is guaranteed solely by the laws of nature. This is in shar

  19. Influence of Water Salinity on Air Purification from Hydrogen Sulfide

    Directory of Open Access Journals (Sweden)

    Leybovych L.I.

    2015-12-01

    Full Text Available Mathematical modeling of «sliding» water drop motion in the air flow was performed in software package FlowVision. The result of mathematical modeling of water motion in a droplet with diameter 100 microns at the «sliding» velocity of 15 m/s is shown. It is established that hydrogen sulfide oxidation occurs at the surface of phases contact. The schematic diagram of the experimental setup for studying air purification from hydrogen sulfide is shown. The results of the experimental research of hydrogen sulfide oxidation by tap and distilled water are presented. The dependence determining the share of hydrogen sulfide oxidized at the surface of phases contact from the dimensionless initial concentration of hydrogen sulfide in the air has been obtained.

  20. Mechanical properties of gutta-percha sulfide modified asphalt

    Science.gov (United States)

    Zou, X. Y.; Gu, X. Y.; Wang, X. W.

    2017-01-01

    Gutta-percha is the isomer of caoutchouc and can be used to enhance the performance of asphalt. In this paper, the produce proceedings of gutta-percha sulfide and gutta-percha sulfide modified asphalt are introduced. The performance indices of gutta-percha sulfide modified asphalt samples with different proportions are examined based on laboratory tests and the optimum ratio of gutta-percha and sulfur is decided.The micromechanism, temperature sensitivity, high and low temperature properties and viscoelasticity of the polymer modified asphalt are analyzed to discuss the modified mechanism and to decide the optimal polymer content. Low temperature bending tests are carried out to verify the low temperature performance of gutta-percha sulfide modified asphalt mixture. Research results showed that gutta-percha sulfide modified asphalt has good low temperature performance and a promising application prospect in the cold regions.

  1. Sulindac Sulfide, but Not Sulindac Sulfone, Inhibits Colorectal Cancer Growth

    Directory of Open Access Journals (Sweden)

    Christopher S. Williams

    1999-06-01

    Full Text Available Sulindac sulfide, a metabolite of the nonsteroidal antiinflammatory drug (NSAID sulindac sulfoxide, is effective at reducing tumor burden in both familial adenomatous polyposis patients and in animals with colorectal cancer. Another sulindac sulfoxide metabolite, sulindac sulfone, has been reported to have antitumor properties without inhibiting cyclooxygenase activity. Here we report the effect of sulindac sulfone treatment on the growth of colorectal carcinoma cells. We observed that sulindac sulfide or sulfone treatment of HCA-7 cells led to inhibition of prostaglandin E2 production. Both sulindac sulfide and sulfone inhibited HCA-7 and HCT-116 cell growth in vitro. Sulindac sulfone had no effect on the growth of either HCA-7 or HCT-116 xenografts, whereas the sulfide derivative inhibited HCA-7 growth in vivo. Both sulindac sulfide and sulfone inhibited colon carcinoma cell growth and prostaglandin production in vitro, but sulindac sulfone had no effect on the growth of colon cancer cell xenografts in nude mice.

  2. Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides

    Directory of Open Access Journals (Sweden)

    Priyanka Jood

    2015-03-01

    Full Text Available Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based layered sulfides, misfit layered sulfides, homologous chalcogenides, accordion-like layered Sn chalcogenides, and thermoelectric minerals. CS2 sulfurization is an appropriate method for preparing sulfide thermoelectric materials. At the atomic scale, the intercalation of guest atoms/layers into host crystal layers, crystal-structural evolution enabled by the homologous series, and low-energy atomic vibration effectively scatter phonons, resulting in a reduced lattice thermal conductivity. At the nanoscale, stacking faults further reduce the lattice thermal conductivity. At the microscale, the highly oriented microtexture allows high carrier mobility in the in-plane direction, leading to a high thermoelectric power factor.

  3. Effect of palladium on sulfide tarnishing of noble metal alloys.

    Science.gov (United States)

    Suoninen, E; Herø, H; Minni, E

    1985-10-01

    Electron spectroscopic studies of Au-Ag-Cu alloys of the type used for dental castings show that small additions (less than or equal to 3 wt%) of palladium reduce essentially the thickness of the sulfide layer formed on surfaces of samples treated in aqueous Na2S solutions. Relative to silver, palladium does not enrich in the sulfide, but statistically significant enrichment is found immediately below the sulfide layer. This enrichment probably takes place during the exposure of the substrate surface to atmosphere before the sulfiding treatment. The mechanism of the impeding effect of palladium on sulfiding is assumed to be a decrease in diffusion from the bulk alloy to the surface due to the enriched layer. The effect cannot be explained by changes in the electronic structure of the alloy due to palladium alloying.

  4. Regulation of bacterial sulfate reduction and hydrogen sulfide fluxes in the central Namibian coastal upwelling zone

    DEFF Research Database (Denmark)

    Bruchert, V.; Jørgensen, BB; Neumann, K.;

    2003-01-01

    and the low capacity to oxidize and trap sulfide. The inner shelf break marks the seaward border of sulfidic bottom waters, and separates two different regimes of bacterial sulfate reduction. In the sulfidic bottom waters on the shelf, up to 55% of sulfide oxidation is mediated by the large nitrate...... to the sediment-water interface and reduce the hydrogen sulfide flux to the water column. Modeling of pore water sulfide concentration profiles indicates that sulfide produced by bacterial sulfate reduction in the uppermost 16 cm of sediment is sufficient to account for the total flux of hydrogen sulfide...... to the water column. However, the total pool of hydrogen sulfide in the water column is too large to be explained by steady state diffusion across the sediment-water interface. Episodic advection of hydrogen sulfide, possibly triggered by methane eruptions, may contribute to hydrogen sulfide in the water...

  5. Carbonyl sulfide: No remedy for global warming

    Science.gov (United States)

    Taubman, Steven J.; Kasting, James F.

    1995-04-01

    The enhancement of the stratospheric aerosol layer caused by the eruption of Mt. Pinatubo (June 15, 1991), and the subsequent cooling of the earth's lower atmosphere [Dutton and Christy, 1992; Minnis et al., 1993] shows that stratospheric aerosols can have a strong effect on the earth's climate. This supports the notion that the intentional enhancement of the stratospheric aerosol layer through increased carbonyl sulfide (OCS) emissions might be an effective means for counteracting global warming. Through the use of a one-dimensional photochemical model, we investigate what effect such a program might have on global average stratospheric ozone. In addition, we consider the impact of enhanced OCS emissions on rainwater acidity and on the overall health of both plants and animals. We find that while the warming produced by a single CO2 doubling (1 to 4°C) might be offset with ozone losses of less than 5%, any attempt to use carbonyl sulfide as a permanent solution to global warming could result in depletion of global average ozone by 30% or more. We estimate that in order to achieve cooling of 4°C rainwater pH would fall to between 3.5 and 3.8. Finally, a 4°C cooling at the surface will require that ambient near ground OCS levels rise to above 10 ppmv which is probably greater than the safe exposure limit for humans. Thus, enhanced OCS emissions do not provide an environmentally acceptable solution to the problem of global warming.

  6. Hydrogen Sulfide and Polysulfides as Biological Mediators

    Directory of Open Access Journals (Sweden)

    Hideo Kimura

    2014-10-01

    Full Text Available Hydrogen sulfide (H2S is recognized as a biological mediator with various roles such as neuromodulation, regulation of the vascular tone, cytoprotection, anti-inflammation, oxygen sensing, angiogenesis, and generation of mitochondrial energy. It is produced by cystathionine β-synthase (CBS, cystathionine γ-lyase (CSE, and 3-mercaptopyruvate sulfurtransferase (3MST. The activity of CBS is enhanced by S-adenosyl methionine (SAM and glutathionylation, while it is inhibited by nitric oxide (NO and carbon monoxide (CO. The activity of CSE and cysteine aminotransferase (CAT, which produces the 3MST substrate 3-mercaptopyruvate (3MP, is regulated by Ca2+. H2S is oxidized to thiosulfate in mitochondria through the sequential action of sulfide quinone oxidoreductase (SQR, sulfur dioxygenase, and rhodanese. The rates of the production and clearance of H2S determine its cellular concentration. Polysulfides (H2Sn have been found to occur in the brain and activate transient receptor potential ankyrin 1 (TRPA1 channels, facilitate the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2 to the nucleus, and suppress the activity of phosphatase and tensin homolog (PTEN by sulfurating (sulfhydrating the target cysteine residues. A cross talk between H2S and NO also plays an important role in cardioprotection as well as regulation of the vascular tone. H2S, polysulfides, and their cross talk with NO may mediate various physiological and pathophysiological responses.

  7. Normal state of metallic hydrogen sulfide

    Science.gov (United States)

    Kudryashov, N. A.; Kutukov, A. A.; Mazur, E. A.

    2017-02-01

    A generalized theory of the normal properties of metals in the case of electron-phonon (EP) systems with a nonconstant density of electron states has been used to study the normal state of the SH3 and SH2 phases of hydrogen sulfide at different pressures. The frequency dependence of the real Re Σ (ω) and imaginary ImΣ (ω) parts of the self-energy Σ (ω) part (SEP) of the Green's function of the electron Σ (ω), real part Re Z (ω), and imaginary part Im Z (ω) of the complex renormalization of the mass of the electron; the real part Re χ (ω) and the imaginary part Imχ (ω) of the complex renormalization of the chemical potential; and the density of electron states N (ɛ) renormalized by strong electron-phonon interaction have been calculated. Calculations have been carried out for the stable orthorhombic structure (space group Im3¯ m) of the hydrogen sulfide SH3 for three values of the pressure P = 170, 180, and 225 GPa; and for an SH2 structure with a symmetry of I4/ mmm ( D4 h1¯7) for three values of pressure P = 150, 180, and 225 GP at temperature T = 200 K.

  8. Hydrogen sulfide and polysulfides as biological mediators.

    Science.gov (United States)

    Kimura, Hideo

    2014-10-09

    Hydrogen sulfide (H2S) is recognized as a biological mediator with various roles such as neuromodulation, regulation of the vascular tone, cytoprotection, anti-inflammation, oxygen sensing, angiogenesis, and generation of mitochondrial energy. It is produced by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST). The activity of CBS is enhanced by S-adenosyl methionine (SAM) and glutathionylation, while it is inhibited by nitric oxide (NO) and carbon monoxide (CO). The activity of CSE and cysteine aminotransferase (CAT), which produces the 3MST substrate 3-mercaptopyruvate (3MP), is regulated by Ca2+. H2S is oxidized to thiosulfate in mitochondria through the sequential action of sulfide quinone oxidoreductase (SQR), sulfur dioxygenase, and rhodanese. The rates of the production and clearance of H2S determine its cellular concentration. Polysulfides (H2Sn) have been found to occur in the brain and activate transient receptor potential ankyrin 1 (TRPA1) channels, facilitate the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) to the nucleus, and suppress the activity of phosphatase and tensin homolog (PTEN) by sulfurating (sulfhydrating) the target cysteine residues. A cross talk between H2S and NO also plays an important role in cardioprotection as well as regulation of the vascular tone. H2S, polysulfides, and their cross talk with NO may mediate various physiological and pathophysiological responses.

  9. First detection of doubly deuterated hydrogen sulfide

    CERN Document Server

    Vastel, C; Ceccarelli, C; Pearson, J

    2003-01-01

    This work was carried out with using the Caltech Submillimeter Observatory and presents the observational study of HDS and D2S towards a sample of Class 0 sources, and dense cores. We report the first detection of doubly deuterated hydrogen sulfide (D2S) in two dense cores and analyze the chemistry of these molecules aiming to help understand the deuteration processes in the interstellar medium. The observed values of the D2S/HDS ratio, and upper limits, require an atomic D/H ratio in the accreting gas of 0.1-1. The study presented in this Letter supports the hypothesis that formaldehyde, methanol and hydrogen sulfide are formed on the grain surfaces, during the cold pre-stellar core phase, where the CO depleted gas has large atomic D/H ratios. The high values for the D/H ratios are consistent with the predictions of a recent gas-phase chemical model that includes H3+ and its deuterated isotopomers, H2D+, D2H+ and D3+ (Roberts et al. 2003).

  10. Calculation of sulfide capacities of multicomponent slags

    Science.gov (United States)

    Pelton, Arthur D.; Eriksson, Gunnar; Romero-Serrano, Antonio

    1993-10-01

    The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A12O3 and TiO2 as components. The model has been extended to calculate a priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO2-Al2O3-TiO2-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria.

  11. CALCULATION OF CONDITIONAL EQUILIBRIUM IN SERIAL MULTIPLE PRECIPITATION OF METAL SULFIDES WITH HYDROGEN SULFIDE STREAM GENERATED FROM SODIUM SULFIDE: A DIDACTIC TOOL FOR CHEMISTRY TEACHING

    Directory of Open Access Journals (Sweden)

    Renata Bellová

    2016-07-01

    Full Text Available Hydrogen sulfide is presented in textbooks as toxic, environmentally unacceptable species, however some positive effects in human metabolism were discovered in the last decades. It is important to offer students also some new information about this compound. As didactic tool in this case may serve serial precipitation of Cd2+, Cu2+, Zn2+, Mn2+ and Pb2+ ions forming various colored sulfides in bubblers with chemically generated hydrogen sulfide stream. This experiment has strong and diverse color effect for enhancing the visual perception to motivate students to understand more abstract and complex information about hydrogen sulfide. It also may be helpful in analytical chemistry courses for conditional precipitation equilibrium teaching and calculations.

  12. Histopathological changes in relation to cadmium concentration in horse kidneys

    Energy Technology Data Exchange (ETDEWEB)

    Elinder, C.G.; Jonsson, L.; Piscator, M.; Rahnster, B.

    1981-10-01

    Histopathological changes in kidney cortex, as observed by light microscopy, are related to cadmium concentration in kidney cortex from 69 normal Swedish horses. Cadmium concentrations in kidney ranged from 11 to 186 ..mu..g Cd/g wet wt with an average of 60 ..mu..g Cd/g, which is considerably higher than those normally found in humans. The microscopical changes were rated and related to cadmium concentrations in kidneys by dose-response curves. A relationship existed between frequency of morphological changes and cadmium concentration in the renal cortex. There was no obvious relationship between age and frequency of histopathological changes. This indicates that in horse kidneys morphological changes occur at cadmium concentrations which are lower than the tentative critical level for humans of 200 ..mu..g Cd/g. It is concluded that horses constitute a population at risk for environmental cadmium contamination.

  13. Study on electrokinetic remediation of cadmium contaminated soils

    Institute of Scientific and Technical Information of China (English)

    SHI Wen-xin; CUI Chong-wei; YU Shui-li; FENG Wei-ming

    2007-01-01

    Kaolinite from a lead-zinc mining district, which was spiked with cadmium, has been treated by electrokinetics to investigate effects of treatment time and applied voltage gradient. The results showed that the increased test duration had induced a higher removal rate of cadmium. Being treated for 7 days, cadmium was removed from kaolinite dramatically. It was also found that higher removal rate happened when a higher voltage gradient was applied and cadmium accumulated near the cathode because pH increased. Increase of pH near the cathode caused accumulation of cadmium. Moreover, it was observed that cation exchange membrane which was placed between kaolinite and cathode could make pH lower than the initial value and avoid the higher pH near the cathode. As a result, the high concentration accumulation of cadmium near the cathode was avoided.

  14. Assessment and management of risk to wildlife from cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Joanna [Division of Life Sciences, Environmental and Occupational Health Sciences Institute, Consortium for Risk Evaluation with Stakeholder Participation, Rutgers University, Piscataway, New Jersey, 08854-8082 (United States)], E-mail: burger@biology.rutgers.edu

    2008-01-15

    Cadmium, a nonessential heavy metal that comes from natural and anthropogenic sources, is a teratogen, carcinogen, and a possible mutagen. Assessment of potential risk from cadmium requires understanding environmental exposure, mainly from ingestion, although there is some local exposure through inhalation. Chronic exposure is more problematic than acute exposure for wildlife. There is evidence for bioaccumulation, particularly in freshwater organisms, but evidence for biomagnification up the food chain is inconsistent; in some bird studies, cadmium levels were higher in species that are higher on the food chain than those that are lower. Some freshwater and marine invertebrates are more adversely affected by cadmium exposure than are birds and mammals. There is very little experimental laboratory research on the effects of cadmium in amphibians, birds and reptiles, and almost no data from studies of wildlife in nature. Managing the risk from cadmium to wildlife involves assessment (including ecological risk assessment), biomonitoring, setting benchmarks of effects, regulations and enforcement, and source reduction.

  15. Quantum Operations as Quantum States

    CERN Document Server

    Arrighi, P; Arrighi, Pablo; Patricot, Christophe

    2004-01-01

    In this article we formalize the correspondence between quantum states and quantum operations, and harness its consequences. This correspondence was already implicit in Choi's proof of the operator sum representation of Completely Positive-preserving linear maps; we go further and show that all of the important theorems concerning quantum operations can be derived as simple corollaries of those concerning quantum states. As we do so the discussion first provides an elegant and original review of the main features of quantum operations. Next (in the second half of the paper) we search for more results to arise from the correspondence. Thus we propose a factorizability condition and an extremal trace-preservedness condition for quantum operations, give two novel Schmidt-type decompositions of bipartite pure states and two interesting composition laws for which the set of quantum operations and quantum states remain stable. The latter enables us to define a group structure upon the set of totally entangled state...

  16. Quantum memory in quantum cryptography

    CERN Document Server

    Mor, T

    1999-01-01

    [Shortened abstract:] This thesis investigates the importance of quantum memory in quantum cryptography, concentrating on quantum key distribution schemes. In the hands of an eavesdropper -- a quantum memory is a powerful tool, putting in question the security of quantum cryptography; Classical privacy amplification techniques, used to prove security against less powerful eavesdroppers, might not be effective when the eavesdropper can keep quantum states for a long time. In this work we suggest a possible direction for approaching this problem. We define strong attacks of this type, and show security against them, suggesting that quantum cryptography is secure. We start with a complete analysis regarding the information about a parity bit (since parity bits are used for privacy amplification). We use the results regarding the information on parity bits to prove security against very strong eavesdropping attacks, which uses quantum memories and all classical data (including error correction codes) to attack th...

  17. Quantum Computing for Quantum Chemistry

    Science.gov (United States)

    2010-09-01

    This three-year project consisted on the development and application of quantum computer algorithms for chemical applications. In particular, we developed algorithms for chemical reaction dynamics, electronic structure and protein folding. The first quantum computing for

  18. Quantum Darwinism

    Science.gov (United States)

    Zurek, Wojciech Hubert

    2009-03-01

    Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system. It explains how the quantum fragility of a state of a single quantum system can lead to the classical robustness of states in their correlated multitude; shows how effective `wave-packet collapse' arises as a result of the proliferation throughout the environment of imprints of the state of the system; and provides a framework for the derivation of Born's rule, which relates the probabilities of detecting states to their amplitudes. Taken together, these three advances mark considerable progress towards settling the quantum measurement problem.

  19. Urinary cadmium and mammographic density in premenopausal women.

    Science.gov (United States)

    Adams, Scott V; Newcomb, Polly A; Shafer, Martin M; Atkinson, Charlotte; Bowles, Erin J Aiello; Newton, Katherine M; Lampe, Johanna W

    2011-08-01

    Mammographic density (MD), a strong marker of breast cancer risk, is influenced by genetic, environmental, and hormonal factors. Cadmium, a persistent and widespread environmental pollutant, has been associated with risk of breast cancer, and laboratory evidence suggests cadmium is a carcinogen in the breast. We investigated the hypothesis that cadmium exposure is associated with higher MD. In a cross-sectional study of MD and urinary cadmium concentration, percentage MD (MD%) and Breast Imaging-Reporting and Data Systems (BI-RADS®) density category were determined from screening mammograms of 190 premenopausal women ages 40-45 years. Women completed a health questionnaire, and the cadmium content of spot urine samples was measured with inductively coupled plasma mass spectrometry and corrected for urine creatinine. Urinary cadmium concentrations are thought to reflect exposure to cadmium during a period of 20-30 years. Multivariable linear regression and logistic regression were used to estimate the strength of association between urinary cadmium and mammographic breast density. Adjusted mean MD% among women in the upper tertile of creatinine-corrected urinary cadmium was 4.6% higher (95% CI: -2.3 to 11.6%) than in women in the lowest cadmium tertile. Each twofold increase in urinary cadmium was associated with higher odds of MD% in the upper tertile (OR: 1.29, 95% CI: 0.82-2.02) or a BI-RADS category rating of "extremely dense" (OR: 1.75, 95% CI: 1.14-2.70). Stronger associations were observed among nulliparous women, and current or former smokers. Exposure to cadmium may be associated with increased breast density in premenopausal women.

  20. Comparison of three methods for accurate quantification of hydrogen sulfide during fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Ugliano, Maurizio, E-mail: maurizio.ugliano@awri.com.au [Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064 (Australia); Henschke, Paul A. [Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064 (Australia)

    2010-02-15

    Two analytical approaches for the rapid measurement of hydrogen sulfide (H{sub 2}S) have been compared to a reference method for their potential application as a rapid procedure for the quantification of H{sub 2}S formed during alcoholic fermentations. In one case, silver nitrate, lead acetate, and mercuric chloride selective detector tubes for the analysis of H{sub 2}S in air were investigated. In the other case, a commercially available kit for the diagnosis of nitrogen starvation in wine fermentations, which is based on the detection of H{sub 2}S, was investigated. Both methods exhibited excellent linearity of response, but the mercuric chloride tube was found to suffer from interferences due to the concomitant presence of mercaptans, which resulted in erroneous H{sub 2}S quantification. A comparative study between the two methods studied and the cadmium hydroxide/methylene blue reference method commonly used to monitor H{sub 2}S indicate that the two new methods displayed better recoveries at low H{sub 2}S concentrations, besides being more rapid and economical. The two new methods were successfully used to quantify production of H{sub 2}S in different grape juice fermentations. The suitability of each method for the study of specific aspects of H{sub 2}S production during fermentation is discussed.

  1. Quantum entanglement and quantum operation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is a simple introduction to quantum entanglement and quantum operations. The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations. It includes remote state preparation by using any pure entangled states, nonlocal operation implementation using entangled states, entanglement capacity of two-qubit gates and two-qubit gates construction.

  2. Quantum entanglement

    CERN Document Server

    Horodecki, R; Horodecki, M; Horodecki, K; Horodecki, Ryszard; Horodecki, Pawel; Horodecki, Michal; Horodecki, Karol

    2007-01-01

    All our former experience with application of quantum theory seems to say: {\\it what is predicted by quantum formalism must occur in laboratory}. But the essence of quantum formalism - entanglement, recognized by Einstein, Podolsky, Rosen and Schr\\"odinger - waited over 70 years to enter to laboratories as a new resource as real as energy. This holistic property of compound quantum systems, which involves nonclassical correlations between subsystems, is a potential for many quantum processes, including ``canonical'' ones: quantum cryptography, quantum teleportation and dense coding. However, it appeared that this new resource is very complex and difficult to detect. Being usually fragile to environment, it is robust against conceptual and mathematical tools, the task of which is to decipher its rich structure. This article reviews basic aspects of entanglement including its characterization, detection, distillation and quantifying. In particular, the authors discuss various manifestations of entanglement via ...

  3. Quantum relations

    CERN Document Server

    Weaver, Nik

    2010-01-01

    We define a "quantum relation" on a von Neumann algebra M \\subset B(H) to be a weak* closed operator bimodule over its commutant M'. Although this definition is framed in terms of a particular representation of M, it is effectively representation independent. Quantum relations on l^\\infty(X) exactly correspond to subsets of X^2, i.e., relations on X. There is also a good definition of a "measurable relation" on a measure space, to which quantum relations partially reduce in the general abelian case. By analogy with the classical setting, we can identify structures such as quantum equivalence relations, quantum partial orders, and quantum graphs, and we can generalize Arveson's fundamental work on weak* closed operator algebras containing a masa to these cases. We are also able to intrinsically characterize the quantum relations on M in terms of families of projections in M \\otimes B(l^2).

  4. β—Correction Spectrophotometric Determination of Cadmium with Cadion

    Institute of Scientific and Technical Information of China (English)

    郜洪文

    1995-01-01

    Cadmium has been determined by β-correction spectrophotometry with cadion,p-nitrobenzenediazoaminoaz-obenzone,and a non-ionic surfactant,tuiton X-100.The real absorbance of a Cd-cadion chelate in the colored solution can be accurately determined and the complex-ratio of cadion with Cd(II) has been worked out to be 2.Beer's law is obeyed over the concentration range of 0-0.20mg/1 cadmium and the detec-tion limit for cadmium is only 0.003mg/1.Satisfactory experimental results are presented with respect to the determination of trace cadmium in wastewaters.

  5. Phytosynthesis of Cadmium Oxide Nanoparticles from Achillea wilhelmsii Flowers

    Directory of Open Access Journals (Sweden)

    Javad Karimi Andeani

    2013-01-01

    Full Text Available The study here deals with the plant synthesis of cadmium oxide nanoparticles using flowers extract of Achillea wilhelmsii as the reducing agent. The photosynthesis is carried out at room temperature in the laboratory ambience. The aqueous cadmium ions when exposed to flower extract were reduced and resulted in their nanoparticles. The synthesized nanoparticles were characterized using techniques such as scanning electron microscope (SEM, Fourier transform infrared spectroscopy (FTIR, and UV-visible absorption spectroscopy. Stable cadmium oxide nanoparticles were formed by treating aqueous solution of cadmium chloride (CdCl2 with the plant flower extracts as reducing agent.

  6. 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.

  7. Lead, mercury, and cadmium in breast milk

    OpenAIRE

    Kadriye Yurdakök

    2015-01-01

    Toxic heavy metals are the major source of environmental pollution in this new millennium. Lead, mercury, and cadmium are the most common toxic heavy metals in the environment. There is no known function of these toxic heavy metals in the human body. In females, toxic heavy metals can be accumulated in maternal body before pregnancy and may be transferred to fetus through placenta and later, via breast milk. Lead previously accumulated in maternal bones can be mobilized along with calcium in ...

  8. 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

  9. Bioaugmentation with cadmium-resistant plant growth-promoting rhizobacteria to assist cadmium phytoextraction by Helianthus annuus.

    Science.gov (United States)

    Prapagdee, Benjaphorn; Chanprasert, Maesinee; Mongkolsuk, Skorn

    2013-07-01

    Micrococcus sp. MU1 and Klebsiella sp. BAM1, the cadmium-resistant plant growth-promoting rhizobacteria (PGPR), produce high levels of indole-3-acetic acid (IAA) during the late stationary phase of their growth. The ability of PGPR to promote root elongation, plant growth and cadmium uptake in sunflowers (Helianthus annuus) was evaluated. Both species of bacteria were able to remove cadmium ions from an aqueous solution and enhanced cadmium mobilization in contaminated soil. Micrococcus sp. and Klebsiella sp. use aminocyclopropane carboxylic acid as a nitrogen source to support their growth, and the minimum inhibitory concentrations of cadmium for Micrococcus sp. and Klebsiella sp. were 1000 and 800mM, respectively. These bacteria promoted root elongation in H. annuus seedlings in both the absence and presence of cadmium compared to uninoculated seedlings. Inoculation with these bacteria was found to increase the root lengths of H. annuus that had been planted in cadmium-contaminated soil. An increase in dry weight was observed for H. annuus inoculated with Micrococcus sp. Moreover, Micrococcus sp. enhanced the accumulation of cadmium in the root and leaf of H. annuus compared to untreated plants. The highest cadmium accumulation in the whole plant was observed when the plants were treated with EDTA following the treatment with Micrococcus sp. In addition, the highest translocation of cadmium from root to the above-ground tissues of H. annuus was found after treatment with Klebsiella sp. in the fourth week after planting. Our results show that plant growth and cadmium accumulation in H. annuus was significantly enhanced by cadmium-resistant PGPRs, and these bacterial inoculants are excellent promoters of phytoextraction for the rehabilitation of heavy metal-polluted environments.

  10. Synthesis of Diaryl Ethers, Diaryl Sulfides, Heteroaryl Ethers and Heteroaryl Sulfides under Microwave Heating

    Institute of Scientific and Technical Information of China (English)

    LI,Feng; ZOU,Jiong; WANG,Quan-Rui; TAO,Feng-Gang

    2004-01-01

    @@ Diaryl ether moiety is found in a pool of naturally occurring and medicinally important compounds.[1] As a consequent, considerable efforts have been devoted to the assembly of this framework.[2] Recently, we have developed a microwave heating version of the synthesis of diaryl ethers as well as aryl sulfides. Under our conditions, even the extremely electron-poor 4-nitrophenol works well and its reaction with 1-halo-4-nitrobenzenes produces 4-(nitrophenoxy)-benzonitriles in satisfactory yield. The scope of the present protocol has been expanded to hydroxylated six-membered heterocycles as well as 2-pyrimidinethiol with mildly activated aryl halides, affording heteroaryl ethers and respectively sulfides. The advantages of the present method include the wide substrate scope, no use of any metal catalysts, the ease of product isolation and high yields.

  11. Influence of bioaccessibility on the toxicity of heavy metal (nickel, chromium, cadmium and lead) species; Einfluss der Resorptionsverfuegbarkeit auf die Toxizitaet von Verbindungen der Schwermetalle Nickel, Chrom, Cadmium und Blei

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, K.; Oltmanns, J.; Kalberlah, F. [FoBiG Forschungs- und Beratungsinstitut Gefahrstoffe GmbH, Freiburg im Breisgau (Germany); Voss, J.U. [Toxikologische Beratung, Chemikalienbewertung - Risikoabschaetzung, Muellheim (Germany)

    2001-07-01

    The risk assessment of heavy metals at hazardous waste sites is based on total elemental concentrations in the soil without differentiation of metal species. This literature study investigates the correlation between bioaccessibility and toxicity of compounds of the heavy metals nickel, chromium, cadmium and lead with low water solubility. Chronic oral toxicity studies for sparsely soluble species are generally lacking. Only for chromic oxide (Cr{sub 2}O{sub 3}) derivation of a tolerable daily dose is possible based on chronic toxicity studies. The chronic oral toxicity of water-soluble chromium-III-compounds can be assessed by comparing effective doses with well-studied, highly toxic Cr-VI-compounds. In general, lower water-solubility is correlated with lower bioaccessibility and lower toxicity in case of the sulfides of nickel, lead and cadmium (and also with nickel oxide and lead chromate). However, some carbonates, oxides and hydroxides (lead oxide, lead carbonate, cadmium oxide, cadmium carbonate, nickel carbonate, nickel hydroxide) show a better solubility in biological media and higher toxicity than expected based solely on poor water solubility. This can be explained by a higher solubility of these compounds in acid environments. Compounds with poor water solubility like nickel oxide and cadmium sulfide are absorbed only to a minor extent from the respiratory tract after inhalation. However, absorption in the respiratory tract is not strictly correlated with bioaccessibility in the gastrointestinal tract. The influence of absorption on respiratory toxicity and on lung carcinogenicity of the heavy metals differs. For example, nickel sulfate, a compound with high water solubility, was toxic in the respiratory tract by inhalation, but not carcinogenic, whereas nickel subsulfide, a compound with lower water solubility, induced lung tumours. For the risk assessment of hazardous waste sites this means that results of in vitro digestive models (for the

  12. Quantum Games and Quantum Discord

    CERN Document Server

    Nawaz, Ahmad

    2010-01-01

    We quantize prisoners dilemma and chicken game by our generalized quantization scheme to explore the role of quantum discord in quantum games. In order to establish this connection we use Werner-like state as an initial state of the game. In this quantization scheme measurement can be performed in entangled as well as in product basis. For the measurement in entangled basis the dilemma in both the games can be resolved by separable states with non-zero quantum discord. Similarly for product basis measurement the payoffs are quantum mechanical only for nonzero values of quantum discord.

  13. Bioavailability of cadmium from linseed and cocoa

    DEFF Research Database (Denmark)

    Hansen, Max; Rasmussen, Rie Romme; Sloth, Jens Jørgen

    2014-01-01

    for the food authorities in order to give correct advises to the population. The aim of this study was to investigate the bioavailability of cadmium from whole linseed, crushed linseed, cocoa and cadmium chloride in rats. An experiment where 40 rats were divided into 4 groups and a control group and dosed...... with whole linseed, crushed linseed, cocoa and CdCl2 for 3 weeks was performed. Linseed or cocoa made up 10% of the feed (by weight) and was added as a replacement for carbohydrate source. The rats were dosed for 3 weeks and the cadmium content in the rats' kidneys was measured by ICPMS as a biomarker...... be measured in the kidney compared to the calculated total intake was as follows: Control 2.0 %, Crushed linseed 0.9 %, whole linseed, 1.5 %, cocoa 0.7 % and CdCl2 4.6 %. Based on this study it could not be concluded that the bioavailability in rats form whole linseed is lower that for crushed linseed...

  14. Occupation, cadmium exposure, and prostate cancer.

    Science.gov (United States)

    Elghany, N A; Schumacher, M C; Slattery, M L; West, D W; Lee, J S

    1990-03-01

    A population-based case-control study was used to investigate associations between prostate cancer and cadmium exposure, longest industry held, and longest occupation held. The study included 358 men with newly diagnosed prostate cancer and 679 control men identified from the Utah population. Occupational exposures to cadmium were ascertained from self-reported data, through several a priori suspect industries and occupations, through an occupation-exposure linkage system, and through dietary food frequency questionnaires. Overall, cadmium exposure appeared to result in a small increased relative risk for prostate cancer, most apparent for aggressive tumors (OR = 1.7, CI = 1.0-3.1 for any occupational exposure, high dietary intake, or smoking cigarettes). Cases were more likely to have worked in the following industries: mining, paper and wood, medicine and science, and entertainment and recreation. Among men younger than 67, cases were also more likely to have worked in the food and tobacco industries (OR = 3.6, CI = 1.0-12.8). Cases were less likely to have worked in industries involved with glass, clay and stone, or rubber, plastics, and synthetics. Men employed as janitors and in other building service occupations showed increased relative risk for aggressive tumors (OR = 7.0, CI = 2.5-19.6). Agricultural occupations did not appear to be related to prostate cancer, although an increased relative risk for aggressive tumors was detected among younger men (OR = 2.6, CI = 0.6-12.1).

  15. Soil ecotoxicity assessment using cadmium sensitive plants

    Energy Technology Data Exchange (ETDEWEB)

    An, Youn-Joo

    2004-01-01

    The crop plants, sorghum and cucumber, can be used as indicator species to assess ecotoxicity of soils contaminated by cadmium. - Four crop plant species (sweet corn, Zea may; wheat, Triticum aestivum; cucumber, Cucumis sativus; and sorghum, Sorghum bicolor) were tested to assess an ecotoxicity in cadmium-amended soils. The measurement endpoints used were seed germination and seedling growth (shoot and root). The presence of cadmium decreased the seedling growth. The medium effective concentration values (EC50) for shoot or root growth were calculated by the Trimmed Spearman-Karber method. Due to the greater accumulation of Cd to the roots, root growth was a more sensitive endpoint than shoot growth. Bioavailability and transport of Cd within plant were related to concentration and species. The ratio of bioaccumulation factor (BAF) in the shoots to the roots indicated high immobilization of Cd in the roots. Seed germination was insensitive to Cd toxicity, and is not recommended for a suitable assay. Among the test plants and test endpoints, root growth of sorghum and cucumber appears to be a good protocol to assess ecotoxicity of soils contaminated by Cd.

  16. Environmental cadmium and breast cancer risk.

    Science.gov (United States)

    Gallagher, Carolyn M; Chen, John J; Kovach, John S

    2010-11-01

    Breast cancer is the most prevalent women's cancer, with an age-adjusted incidence of 122.9 per 100,000 US women. Cadmium, a ubiquitous carcinogenic pollutant with multiple biological effects, has been reported to be associated with breast cancer in one US regional case-control study. We examined the association of breast cancer with urinary cadmium (UCd), in a case-control sample of women living on Long Island (LI), NY (100 with breast cancer and 98 without), a region with an especially high rate of breast cancer (142.7 per 100,000 in Suffolk County) and in a representative sample of US women (NHANES 1999-2008, 92 with breast cancer and 2,884 without). In a multivariable logistic model, both samples showed a significant trend for increased odds of breast cancer across increasing UCd quartiles (NHANES, p=0.039 and LI, p=0.023). Compared to those in the lowest quartile, LI women in the highest quartile had increased risk for breast cancer (OR=2.69; 95% CI=1.07, 6.78) and US women in the two highest quartiles had increased risk (OR=2.50; 95% CI=1.11, 5.63 and OR=2.22; 95% CI=.89, 5.52, respectively). Further research is warranted on the impact of environmental cadmium on breast cancer risk in specific populations and on identifying the underlying molecular mechanisms.

  17. Cadmium and zinc in pregnancy and lactation

    Energy Technology Data Exchange (ETDEWEB)

    Lucis, O.J.; Lucis, R.; Shaikh, Z.A.

    1972-07-01

    Radioactive cadmium (/sup 109/Cd) and zinc (/sup 65/Zn) were injected subcutaneously into pregnant rats. More cadmium than zinc was found in the placentae. After birth, newborns showed detectable /sup 109/Cd only in liver, gastrointestinal tract, and in the brain tissue. Zinc 65 was present in all newborns' tissues. During lactation, highest output of /sup 65/Zn was in colostrum and, on subsequent days, /sup 65/Zn in milk declined rapidly. Cadmium 109 in milk was present in low concentration throughout the lactation period. Rats injected with /sup 109/Cd and /sup 65/Zn after parturition excreted these isotopes in milk in a similiar pattern. Newborns nursed on radioactive milk showed rapid absorption of /sup 65/Zn, whereas /sup 109/Cd accumulated primarily in the intestinal tract; a lesser quantity of /sup 109/Cd was deposited in the liver. In other organs, only /sup 65/Zn was found. The lactating mammary gland contained more /sup 109/Cd than /sup 65/Zn; after lactation, /sup 65/Zn was depleted, whereas /sup 109/Cd remained in mammary tissue.

  18. Measurement of plasma hydrogen sulfide in vivo and in vitro.

    Science.gov (United States)

    Shen, Xinggui; Pattillo, Christopher B; Pardue, Sibile; Bir, Shyamal C; Wang, Rui; Kevil, Christopher G

    2011-05-01

    The gasotransmitter hydrogen sulfide is known to regulate multiple cellular functions during normal and pathophysiological states. However, a paucity of concise information exists regarding quantitative amounts of hydrogen sulfide involved in physiological and pathological responses. This is primarily due to disagreement among various methods employed to measure free hydrogen sulfide. In this article, we describe a very sensitive method of measuring the presence of H₂S in plasma down to nanomolar levels, using monobromobimane (MBB). The current standard assay using methylene blue provides erroneous results that do not actually measure H₂S. The method presented herein involves derivatization of sulfide with excess MBB in 100 mM Tris-HCl buffer (pH 9.5, 0.1 mM DTPA) for 30 min in 1% oxygen at room temperature. The fluorescent product sulfide-dibimane (SDB) is analyzed by RP-HPLC using an eclipse XDB-C18 (4.6 × 250 mm) column with gradient elution by 0.1% (v/v) trifluoroacetic acid in acetonitrile. The limit of detection for sulfide-dibimane is 2 nM and the SDB product is very stable over time, allowing batch storage and analysis. In summary, our MBB method is suitable for sensitive quantitative measurement of free hydrogen sulfide in multiple biological samples such as plasma, tissue and cell culture lysates, or media.

  19. Sulfide elimination by intermittent nitrate dosing in sewer sediments

    Institute of Scientific and Technical Information of China (English)

    Yanchen Liu; Chen Wu; Xiaohong Zhou; David Z.Zhu; Hanchang Shi

    2015-01-01

    The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards,and requires expensive programs for its prevention.The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments.The study was carried out based on lab-scale experiments and batch tests using real sewer sediments.The intermittent nitrate dosing mode and the optimal control condition were investigated.The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment.The oxidation-reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S (nitrate/sulfide)ratio with slight excess nitrate is necessary for optimal conditions ofefficient sulfide control with lower carbon source loss.The opth-nal control condition is feasible for the sulfide elimination in sewer systems.

  20. Azo dye decolorization assisted by chemical and biogenic sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Prato-Garcia, Dorian [Laboratory for Research on Advanced Processes for Water Treatment, Unidad Académica Juriquilla, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76230 (Mexico); Cervantes, Francisco J. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José 2055, San Luis Potosí 78216 (Mexico); Buitrón, Germán, E-mail: gbuitronm@ii.unam.mx [Laboratory for Research on Advanced Processes for Water Treatment, Unidad Académica Juriquilla, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76230 (Mexico)

    2013-04-15

    Highlights: ► Azo dyes were reduced efficiently by chemical and biogenic sulfide. ► Biogenic sulfide was more efficient than chemical sulfide. ► There was no competition between dyes and sulfate for reducing equivalents. ► Aromatic amines barely affected the sulfate-reducing process. -- Abstract: The effectiveness of chemical and biogenic sulfide in decolorizing three sulfonated azo dyes and the robustness of a sulfate-reducing process for simultaneous decolorization and sulfate removal were evaluated. The results demonstrated that decolorization of azo dyes assisted by chemical sulfide and anthraquinone-2,6-disulfonate (AQDS) was effective. In the absence of AQDS, biogenic sulfide was more efficient than chemical sulfide for decolorizing the azo dyes. The performance of sulfate-reducing bacteria in attached-growth sequencing batch reactors suggested the absence of competition between the studied azo dyes and the sulfate-reducing process for the reducing equivalents. Additionally, the presence of chemical reduction by-products had an almost negligible effect on the sulfate removal rate, which was nearly constant (94%) after azo dye injection.