Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cadmium Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2005

HAADF imaging: an effective technique for the study of nonhomogeneous nanostructures.

Atomic number contrast (Z-contrast) imaging using high-angle annular dark field (HAADF) detector, along with high resolution electron microscopy (HREM), is used to study the nanostructured metal, semiconductor, mixed oxide, and soft matter composites of inhomogeneous nature. A comparison between the HREM and HAADF images for the analysis of crystal structure, defects, and compositional inhomogenity in those nanostructures has been made. While the HREM technique is efficient in determining bulk crystallinity and defect structures, the HAADF imaging technique is superior in determining the surface inhomogenity, defect structures in the interior of the nanostructures, even at atomic resolution. The efficiency of the HAADF imaging technique in determining the surface inhomogenity and defect structures is demonstrated for the Au-Pt bimetallic clusters, CdSe nanofibers and nanowires, Nb16W18O94 mixed oxide, and polystyrene-mormorillonite clay nanocomposites.

Cadmium Compounds↗
PubMed2005

Optical studies on chemical bath deposited nanocrystalline CdS thin films.

Nanocrystalline cadmium sulphide thin films were prepared by the chemical bath (CB) deposition using a mixed aqueous solution of cadmium chloride, thiourea, and ammonium chloride. The XRD patterns showed that the CdS films were of hexagonal phase with preferred (002) orientation. From ellipsometric measurements, the film thickness was found to be in order of 66 nm and the optical band gap was estimated to be 2.4 eV.

Ammonium Chloride↗
PubMed2005

Single-crystal CdSe nanowires prepared via vapor-phase growth assisted with silicon.

Hexagonal cadmium selenide (CdSe) nanowires, with diameter around 20 nm, were synthesized using a simple vapor-phase growth. Silicon (Si) powder acts as a source material assisting the synthesis, which is very important to the formation of the CdSe nanowires. We also suggest that self-catalysis at the Cd-terminated (0001) surface, together with the assistance action of Si, leads to the formation of wire-like structures to be formed. Meanwhile, the assistance of Si is responsible for the fineness and uniformity of the CdSe nanowires. The possible growth mechanism of the CdSe nanowires is proposed, and the optical property of the as-grown CdSe nanowires is characterized.

Cadmium Compounds↗
PubMed2005

Synthesis of CdS and alloyed CdMnS nanocrystals using aqueous foams.

Certain surfactant-stabilized aqueous foams provide a potentially efficient and simple chemical route for the synthesis of various nanomaterials with controllable structure, size, and shape. In the present work, a one-step process for the synthesis of CdS and Cd1-xMn(x)S (0 < x < 10) nanocrystals has been described. Aqueous CdCl2 and the aerosol-OT solutions are homogeneously mixed together and thereafter, nitrogen is bubbled through this solution to produce stable aqueous foam. After drainage of the foam, the freestanding dry foam consisting of cadmium cations electrostatically complexed with the anionic aerosol-OT molecules at the liquid-gas interface is treated with H2S vapor. The foam turns yellowish-orange and collapses, in the process yielding CdS nanoclusters of variable morphology. This morphology variation is appropriately attributed to growth of the CdS as well as alloyed Cd1-xMn(x)S nanoparticles in different regions of the foam contributing to the varying topological structure. Optical absorption spectra of both CdS and Cd1-xMn(x)S nanoparticles clearly show a well-defined exciton absorption feature around 450 nm due to quantum confinement effects. The interesting band edge emission characteristics of these AOT-capped CdS and Cd1-xMn(x)S nanoparticles produced in the foam are discussed with respect to their size and shape. Particular interest in the present novel aqueous foam approach arises due to the fact that the cubic zincblende CdS and alloyed Cd1-xMn(x)S nanocrystals could easily be obtained even under ambient experimental conditions itself.

Alloys↗
PubMed2005

One-dimensional semiconductor nanostructures as absorber layers in solar cells.

The one-dimensional (1-D) nanostructures of cadmium chalcogenides (Il-VI: CdSe, CdTe), InP and GaAs (III-V), and the ternary chalcopyrites CulnS2, CulnSe2, and CulnTe2 (I-III-VI2) are the candidate semiconductors of interest as absorber layers in solar cells. In the confinement regime (approximately 1-10 nm) of these 1-D nanostructures, the electronic energy levels are quantized so that the oscillator strength and the resultant absorption of solar energy are enhanced. Moreover, the discrete energy levels effectively separate the electrons and holes at the two electrodes or at the interfaces with a polymer in a hybrid structure, so that an oriented and 1-D nanostructured absorber layer is expected to improve the conversion efficiency of solar cells. The intrinsic anisotropy of Il-VI and l-lll-VI2 crystal lattices and the progress in various growth processes are assessed to derive suitable morphological features of these 1-D semiconductor nanostructures. The present status of research in nanorod-based solar cells is reviewed and possible routes are identified to improve the performance of nanorod-based solar cells. Finally, the characteristics of nanorod-based solar cells are compared with the dye-sensitized and organic solar cells.

Anisotropy↗
PubMed2006

Self-organized CdSSe quantum dots thin films.

Self-organized and strained CdSSe quantum dot (Q-dot) thin films have been grown on ITO-coated glass substrates by novel wet chemical route. The Q-dots are (002) oriented faceted pyramids with average particle size of 7.5 nm. The X-ray diffraction results reveal the formation of a solid solution of CdSSe. Atomic force microscopy is used to investigate the morphology of the nanocrystalline thin films. The energy dispersive X-ray analysis spectrum confirms the presence of Cd, S, and Se in the films. Optical absorption and photoluminescence spectra show the blue shift for quantum dot thin films.

Cadmium Compounds↗
PubMed2006

Generation of CdS nano-necklaces and NiS nanotubes templated by sugar-appended hydrogel.

A new hydrogel based on glucose-appended Schiff base derivative has been employed as the template to synthesize CdS and NiS nanostructures with different morphologies. The FT-IR and UV-vis results revealed that H-bonding and pi-pi interaction played important roles in the formation of original hydrogel fibers. The study of mineralization mechanism suggested that the inorganic ions were firstly adsorbed at the surface of the hydrogel fibers due to the hydrophilic affinity with the hydrophilic glucose groups. With the penetration of H2S gas, the preformed CdS or NiS nanoparticles on the surface of the fibers acted as the growing points for the continuous growth. And the different adsorption abilities of the metal ions at the hydrogel fibers resulted in the formation of CdS nano-necklaces and NiS nanotubes.

Cadmium Compounds↗
PubMed2006

Self-surface passivation of CdX (X = Se, Te) quantum dots.

A small portion of a reaction mixture including unpurified CdX (X = Se or Te) quantum dots (QDs), in which unreacted Cd and Se ions were left together with coordinating solvents, was dropped into an organic solvent. The CdX QDs in this organic solution showed enhancement of photoluminescence (PL) efficiency, growth of particles, and focusing of size distribution for more than 10 h at room temperature (RT, -23 degrees C). These effects were attributed to passivation of QDs' surface by Cd and X ions present in the solution. No external energy source was used for these achievements; therefore, the process is termed as self-surface passivation. The self-surface passivation was reproduced using purified CdX QDs with additional Cd and X ions in an organic solvent. The self-surface passivation method was applied to RT-synthesized CdSe QDs, which is characterized by a broad PL spectrum (fwhm - 150 nm) for monodispersed QDs, to modify their emission characteristics. On self-surface passivation, the broad PL spectrum was narrowed (fwhm - 35 nm) and the QDs were grown. The X-ray diffraction measurements of RT-synthesized CdSe QDs and that subsequently aged in 1-butanol showed that crystallinity of the samples was improved on aging.

Cadmium Compounds↗
PubMed2006

Synthesis and characterization of metal selenide (ZnSe, CdSe, HgSe) nanoparticles.

Thermolysis of [M(SeCH2CH2CH2NMe2)2] (M = Zn, Cd, Hg), prepared by the reactions of sodium salt of 3-(N,N-dimethylamino)propaneselenolate with metal acetates, afforded metal selenides (MSe). The metal selenides were characterized by XRD, EDAX, SEM, AFM, and TEM techniques. Nanoparticles of HgSe were prepared by pyrolysis in a quartz boat, solvothermal, and sonochemical methods. EDAX showed 1:1 Hg/Se ratio, while XRD and SAED patterns confirmed the formation of cubic HgSe. These particles are spherical in nature with an average diameter of 15 nm (from TEM).

Cadmium Compounds↗
PubMed2006

Synthesis and properties of water-soluble core-shell-shell silica-CdSe/CdS-silica nanoparticles.

This paper describes the synthesis of highly water-soluble and fluorescent core-shell-shell silica-CdSe/CdS-silica nanoparticles (CSS silica-QDs-silica NPs). We used cadmium nitrate and 1,1-dimethyl-2-selenourea precursors to synthesize CdSe quantum dots (QDs) in aqueous solution under simultaneous illumination with a diode-pumped solid state green laser and a Xe-Hg lamp. After passivation of the CdSe QDs with CdS, the CdSe/CdS QDs were then conjugated covalently to (3-mercaptopropyl)trimethoxysilane (MPS); we call these nanoparticles "MPS-QDs". We mixed the MPS-QDs with tetraethoxysilane (TEOS), ethanol, and NH3. By controlling the concentrations of the reagents, the stirring speed, and the reaction time, we synthesized CSS silica-QDs-silica NPs having sizes ranging from 75 to 190 nm. The incubation time for preparing the MPS-QDs and their concentrations are important parameters in determining the morphologies of the CSS silica-QDs-silica NPs. When we mixed 50 nM MPS-QDs, 1.1 mM TEOS, and 78 mM NH3 and reacted them at a stirring speed of 750 rpm, we obtained 85-nm-diameter CSS silica-QDs-silica NPs having a QD shell thickness of about 20 nm. The CSS silica-QDs-silica NPs provide a strong photoluminescence intensity (quantum yield 88%) and exhibit enhanced stability both photochemically and in high-conductivity media (e.g., 1.0 M NaCl).

Cadmium Compounds↗
PubMed2006

Shake and break--shaking-induced changes of size quantization in aggregated quantum dots.

We show how simple mechanical agitation of precipitated CdSe quantum dot aggregates causes partially reversible color changes (clearly visible to the eye) in the absorption spectrum of the CdSe (about 4 nm size). The color changes, which are due to changes in size quantization, are not accompanied by change in quantum dot size. This phenomenon is explained by partial deaggregation of the precipitates, leading to reduced charge overlap between neighboring dots. Shaking was shown to result in a looser aggregate structure. It is suggested that CdSO3 particles (an initial product of the CdSe formation reaction) act as weak bridges between CdSe quantum dots, mediating the interparticle interactions and allowing the deaggregation to occur on shaking.

Cadmium Compounds↗
PubMed2006

Organization of nanoparticles on hard substrates using block copolymer films as templates.

We present a technique for the organization of pre-synthesized nanoparticles on hard substrates, using block copolymer films as sacrificial templates. A thin block copolymer film is dip-coated on the substrate of interest and the sample is exposed to a solution containing nanoparticles. Spontaneous preferential adsorption of the nanoparticles on one phase of the block copolymer film results in their lateral organization. An oxygen plasma etch is used to remove the polymer film; the nanoparticles end up organized on the substrate. We demonstrate that this is a general approach for the patterning of inorganic nanoparticles on hard substrates, showing the organization of metal and semiconductor nanoparticles having different chemistries at the particle/solvent and solvent/polymer interfaces. The nanoparticle patterns that we present have typical periodicities in the nanometer scale. In some cases, microcontact printing is used to create a double length scale of organization, on the micrometer and on the nanometer level. The characteristic periodicity of the template is studied with respect to the nanoparticle size in order to optimize the organization. Finally, we describe how to extend this technique for the production of continuous gold nanowires on hard substrates. We expect that the flexibility of this approach and the degree of control that can be obtained over nanoparticle organization should make it a powerful tool for nanoscale fabrication.

Cadmium Compounds↗
PubMed2006

Sonochemical synthesis of CdS and CdSe nanowires.

A convenient sonochemical route was developed to fabricate one-dimensional (1D) CdS or CdSe assemblies via a simple template method with two-steps: Firstly, the colloid one dimensional cadmium hydroxide particles were prepared as templates under sonication; then, the colloid particles were converted into 1D CdS or CdSe assemblies via a replacement reaction after the surface nucleation and crystal growth processes. The as-prepared CdS and CdSe nanowires were characterized by XRD, TEM, XPS, and UV-visible Spectroscopy. The effects of the ultrasonic irradiation were discussed. It is believed that the ultrasound irradiation played a positive role in both the assembly of the colloid cadmium hydroxide particles into the 1D structure and the growth of CdSe and CdS nanowires. The effects of pH on the morphologies of the cadmium hydroxide template were also discussed. The band gaps of the as-prepared 1D CdSe and CdS assemblies were calculated to be 3.1 eV and 4.9 eV, respectively, indicating the quantum size effect. The as-prepared products might have potential applications in nanodevices in future.

Cadmium Compounds↗
PubMed1984

Liver hyperplasia and regression after lead nitrate administration.

The effect of a single intravenous injection of lead nitrate on liver, was investigated in male Wistar rats. Lead nitrate at 5 and 10 mumoles/100 g of body weight stimulated a 19-fold increase in the incorporation of 3H-thymidine into liver DNA and resulted in temporal changes in DNA synthesis, as determined by assays of specific activity. Thirty-six hours after lead nitrate administration, the incorporation of 3H-thymidine reached its maximum and returned to normal levels within 3 days. A significant increase in the number of cells entering mitosis at 36 hours indicated the capacity of lead to stimulate liver cell proliferation. Enlargement of the liver after lead treatment was also observed in both female Wistar rats as well in male Fischer rats. This stimulatory effect of lead on liver growth was reversible; during the involution of the liver, cell death morphologically similar to the one described as apoptosis was observed in histological sections of liver from animals sacrificed 4-7 days after lead treatment.

Animals↗
PubMed1997

HSF1 granules: a novel stress-induced nuclear compartment of human cells.

Heat shock factor 1 (HSF1) is the ubiquitous stress-responsive transcriptional activator which is essential for the inducible transcription of genes encoding heat shock proteins and molecular chaperones. HSF1 localizes within the nucleus of cells exposed to heat shock, heavy metals, and amino acid analogues, to form large, irregularly shaped, brightly staining granules which are not detected during attenuation of the heat shock response or when cells are returned to their normal growth conditions. The kinetics of detection of HSF1 granules parallels the transient induction of heat shock gene transcription. HSF1 granules are also detected using an HSF1-Flag epitope tagged protein or a chimeric HSF1-green fluorescent protein which reveals that these nuclear structures are stress-induced and can be detected in living cells. The spatial organization of HSF1 granules in nuclei of stressed cells reveals that they are novel nuclear structures which are stress-dependent and provides evidence that the nucleus undergoes dynamic reorganization in response to stress.

Amino Acids↗
PubMed2000

Structure and dynamics of hnRNP-labelled nuclear bodies induced by stress treatments.

We have previously described HAP, a novel hnRNP protein that is identical both to SAF-B, a component of the nuclear scaffold, and to HET, a transcriptional regulator of the gene for heat shock protein 27. After heat shock, HAP is recruited to a few nuclear bodies. Here we report the characterisation of these bodies, which are distinct from other nuclear components such as coiled bodies and speckles. The formation of HAP bodies is part of a general cell response to stress agents, such as heat shock and cadmium sulfate, which also affect the distribution of hnRNP protein M. Electron microscopy demonstrates that in untreated cells, similar to other hnRNP proteins, HAP is associated to perichromatin fibrils. Instead, in heat shocked cells the protein is preferentially associated to clusters of perichromatin granules, which correspond to the HAP bodies observed in confocal microscopy. Inside such clusters, perichromatin granules eventually merge into a highly packaged 'core'. HAP and hnRNP M mark different districts of these structures. HAP is associated to perichromatin granules surrounding the core, while hnRNP M is mostly detected within the core. BrU incorporation experiments demonstrate that no transcription occurs within the stress-induced clusters of perichromatin granules, which are depots for RNAs synthesised both before and after heat shock.

Cadmium Compounds↗
PubMed1986

An improved technique of intra-operative bone scanning.

Radiopharmaceuticals have been successfully used to detect occult neoplasms and infective lesions. Bone scans using 99mTc-labelled methylene diphosphonate located osteoid osteomas accurately in a series of 30 symptomatic patients. A portable radiation detector system has been designed to help intra-operative localisation and facilitate complete excision of the lesions with minimal damage to normal tissue. A sodium iodide detector with a fibre-optic link was used at first, but a cadmium telluride system has provided a more durable, reliable and sensitive sterilisable probe.

Adolescent↗
PubMedDate not supplied

Nonselective cation current in rabbit ventricular myocytes.

Currents contributing repolarization in rabbit ventricular myocytes are very complex because the I(to.s) covers almost the whole repolarization phase of the action potential. The other components of repolarizing currents, such as I(Kr) and I(Ks), are small. In the present work, with whole-cell patch-clamp technique, a clear evidence was provided for the existence of a hitherto unreported, voltage-dependent, nonselective cation current (NSCC) in rabbit ventricular myocytes. Na(+), K(+), and Cs(+) can permeate through the nonselective cation channel and the NSCC can be blocked by Gd(3+). The channels are sensitive to Ca(2+), Mg(2+)-free, and insulin in bathing solution. Activation of NSCC may provide complex effects on action potential configuration depending on the basal conditions and the experimental situations. Considering the voltage dependence and rapid activation kinetics of this current, we speculate that this current can provide an important influence on all repolarization phases of the action potential as well as contribute to the resting membrane potential in rabbit ventricular myocytes. In addition, it is conceivable that, under certain pathophysiological conditions (e.g., ischemia or excessive mechanical stress), the sensitivity of the channels could be altered in such a way that the conductance opens even in the presence of physiological Ca(2+), Mg(2+), and insulin. It might be an important factor on the repolarization of the action potential. Changes in NSCC may lead to an induction or inhibition of arrhythmia.

4-Aminopyridine↗