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Results for “Microscopy, Ultraviolet”

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At least 523 records · Page 29Linked to original sources
PubMed2006

Electrical and optical properties of C46H22N8O4KM (M=Co, Fe, Pb) molecular-material thin films prepared by the vacuum thermal evaporation technique.

In this work, the synthesis of new materials formed from metallic phthalocyanines (Pcs) and double potassium salt from 1,8-dihydroxianthraquinone is reported. The newly synthesized materials were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), infrared (IR) and Ultraviolet-visible (UV-vis) spectroscopy. The powder and thin-film samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds as in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The effect of temperature on conductivity and electrical conduction mechanism was measured in the thin films (approximately 137 nm thickness). They showed a semiconductor-like behaviour with an optical activation energy arising from indirect transitions of 2.15, 2.13 and 3.6eV for the C(46)H(22)N(8)O(4)KFe, C(46)H(22)N(8)O(4)KPb and C(46)H(22)N(8)O(4)KCo thin films.

Cobalt↗
PubMed2006

Microwave-assisted one-step synthesis of polyacrylamide-metal (M = Ag, Pt, Cu) nanocomposites in ethylene glycol.

Polyacrylamide-metal (M = Pt, Ag, Cu) nanocomposites with metal nanoparticles homogeneously dispersed in the polymer matrix have been successfully prepared with the corresponding metal salt and acrylamide monomer in ethylene glycol by microwave heating. This method is based on the single-step simultaneous formation of metal nanoparticles and polymerization of the acrylamide monomer, leading to a homogeneous distribution of metal nanoparticles in the polyacrylamide matrix. Ethylene glycol acts as both a reducing reagent and a solvent, thus no additional reductant is needed. Another advantage is that no initiator for AM polymerization and no surfactant for stabilization of metal nanoparticles are necessary. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), ultraviolet visible (UV-vis) absorption spectra, and thermogravimetric (TG) and differential scanning calorimetric analysis (DSC).

Acrylic Resins↗
PubMed1990

[Ultrastructural changes in the erythrocytes irradiated with ultraviolet light].

The ultrastructure of erythrocytes of donor blood and blood of patients suffering from kidney insufficiency was studied with the help of scanning and transmission electron microscopes before and after it was treated with ultraviolet light. It was concluded that after being treated with ultraviolet light, the ultrastructure of donor blood erythrocytes undergoes significant positive changes which are being characterized by normalization of the form of cells, decrease of associative ties between them, the cytoplasm content becomes more homogenous. There was a noticeable increase of a number of discocytes and a decreased number of associative ties between the cells after the patients' own blood was treated with ultraviolet light. The violation of the wholesomeness of erythrocytes membrane was not discovered. The indications are that the observed therapeutical effect after treating blood with ultraviolet light, is explained, to a certain extent, by the ultrastructural modification of erythrocytes membrane.

Blood Donors↗
PubMed1987

High-performance liquid chromatographic determination of ferulic acid in wheat milling fractions as a measure of bran contamination.

A high-performance liquid chromatographic method was developed for selective determination of ferulic acid in 7 min in the extracts from wheat flour and ground whole wheat at typical levels of 50 and 500 micrograms/g, respectively. Recovery of 99.9% was obtained when ferulic acid was extracted into dilute sulfuric acid, followed by enzymatic treatment of the extract with an alpha-amylase preparation. The chromatographic system included a 100-mm column packed with Hypersil 5 micron reversed-phase ODS operating isocratically with 12% methanol-citrate buffer (pH 5.4) mixture. The selectivity and sensitivity of both ultraviolet diode array and fluorescence detectors was investigated. The optimum wavelengths selected were 320 nm and 312 nm/418 nm respectively. Relative standard deviations of the analytical procedure were 2.43% and 5.10% for whole wheat and flour samples, respectively.

Chromatography, High Pressure Liquid↗
PubMed1992

Characteristics of antigen-presenting cells involved in contact sensitization of normal and UV-irradiated mice.

Exposure of mice to ultraviolet (UV)-B (280-320 nm) radiation alters their immune response to contact-sensitizing haptens applied to UV-irradiated skin. Under these conditions, the contact-hypersensitivity response is reduced, and hapten-specific suppressor T lymphocytes can be found in the spleen. Considerable evidence suggests that the epidermal Langerhans cell is one of the principal targets of this effect of UV irradiation that leads, ultimately, to suppressor cell formation. We are using a combination of cell-surface markers and light and electron microscopy to determine whether differences can be detected in the antigen-presenting cells involved in contact sensitization of normal and UV-irradiated mice.

Animals↗
PubMed1972

Experimental renal disease induced by DNA-anti-DNA immune complexes.

Rabbits immunized with ultraviolet-irradiated DNA (UV-DNA) produced high titers of serum antibody. This experimental model was studied to determine if injection of antigen (UV-DNA) intravenously into immunized animals would induce glomerulonephritis and proteinuria. Proteinuria was observed several days after the start of daily intravenous injections into immunized animals and was sustained as long as injections were continued, but fell to normal values after stopping antigen administration. The kidneys showed glomerulitis sometimes associated with focal proliferative lesions, and immunofluorescence showed rabbit Ig and C3 in glomeruli. By electron microscopy, electron-dense subendothelial deposits were seen. Sucrose density gradient analyses of sera immediately after antigen injections suggested the presence of immune complexes of DNA and antibody since both heavy sedimenting and 7S Ig were detected. After digestion with deoxyribonuclease rabbit Ig could be found only in the 7S sedimenting fractions. Intravenous injection of UV-DNA into normal, nonimmune animals did not produce heavy sedimenting Ig or abnormal sedimentation patterns. These studies with an experimental model might provide insight into pathogenetic mechanisms operating in systemic lupus erythematosus where the importance of DNA-anti-DNA immune complexes have been documented. The studies suggested that gradual accumulation of DNA immune complexes in glomeruli might be one mechanism causing renal functional abnormalities.

Animals↗
PubMed1994

Modification of layered atelocollagen by ultraviolet irradiation and chemical cross-linking: structure stability and mechanical properties.

Physical and chemical modifications of atelocollagen materials have been carried out to improve their physical, chemical and biological properties. We have studied the influence of physical modification using ultraviolet irradiation and of chemical modification using hexamethylene diisocyanate on the physical properties of layered atelocollagen materials. The study evaluated the structural stability of cross-linked materials using swelling experiments. Influence on mechanical properties is also discussed.

Animals↗
PubMed2003

[Effect of exogenous nitrogen oxide on the hamster buccal sac capillaries after ultraviolet exposure].

Effects of exogenous nitrogen oxide (NO) on the time course of results of laser Doppler flowmetry (LDF) and biomicroscopy of the buccal sac capillaries were studied in a hamster pre-exposed to UV light. After NO treatment capillary vasodilatation was replaced by vasoconstriction in the focus of UV exposure. Parameters calculated by Dopplerograms indicate an increase of the vascular tone.

Animals↗
PubMed1991

Effects of high hydrostatic pressure on characteristics of pork slurries and inactivation of microorganisms associated with meat and meat products.

Pork slurries inoculated with various test microorganisms were prepared and subjected to high hydrostatic pressure at 1000 to 6000 atm for 10 min at 25 degrees C to examine for the pressure effects on characteristics of the slurries and the inactivation of the microorganisms associated with meat and meat products. Pressure treatment at higher than 3000 atm caused coagulation and discoloration of the pork slurries. Harder and more white coagulants were obtained by increasing the pressure. Pressure treatment at 3000 to 6000 atm killed all the microorganisms tested by more than 6-log colony-forming units (cfu)/g except Bacillus cereus spores. Gram-negative microorganisms were more labile to pressure than Gram-positive ones. Campylobacter jejuni, Pseudomonas aeruginosa, Salmonella typhimurium and Yersinia enterocolitica were inactivated at pressures higher than 3000 atm; Escherichia coli, Saccharomyces cerevisiae and Candida utilis at pressures higher than 4000 atm; Micrococcus luteus, Staphylococcus aureus and Streptococcus faecalis at 6000 atm. Only less than one-log cfu/g of B. cereus spores were inactivated at 6000 atm. Ultraviolet absorption spectra and acridine orange staining suggested that E. coli became permeable and leaked cytoplasmic RNA at lower pressure than S. aureus. From the present findings, the authors propose high hydrostatic pressure treatment as a promising means of preparing wholesome meat and meat products.

Animals↗
PubMed1997

Cell surface and organelle transport share the same enzymatic properties in Reticulomyxa.

Reticulomyxa transports particulates, like bacterial and algal prey items, bidirectionally along the outside of its pseudopodia. This cell surface transport and intracellular organelle transport can be reactivated in detergent permeabilized cell models [Orokos et al., 1997: Cell Motil. Cytoskeleton]. We have used this unique system to compare cell surface and organelle mechanochemistry in situ in the same reactivated pseudopodia. The ATPase activities of both types of transport were indistinguishable; each displayed identical nucleoside triphosphate specificity, transport ATPase kinetics, and inhibitor sensitivity. Organelle and cell surface transport reactivation required "hydrolyzable" adenosine nucleoside triphosphates; neither reactivated with GTP, CTP, UTP, ITP, AMP-PNP, AMP-PCP, or ATP-gamma-S. However, other ATP analogues, such as 2'-deoxy-ATP and 3'-deoxy-ATP and 2',3'-dideoxy-ATP, supported the reactivation of organelle and cell surface transport at similar, but markedly reduced, velocities. Both transport processes were inhibited similarly by known inhibitors of dynein ATPases such as erythro-9-(3-[2-hydroxynonyl]) adenine (EHNA) or sodium (Na)-orthovanadate. N-ethylmaleimide (NEM) and ultraviolet (UV) irradiation in the presence of Na-orthovanadate and ATP permanently disabled both transport processes. Organelle and surface transport followed identical Michaelis-Menten kinetics with a calculated Km of 118 microM ATP and a maximum translocation velocity (Vmax) of 8.33 microm/sec. These findings strongly suggest that cell surface transport shares the same cytoplasmic dynein motor [Schliwa et al., 1991: J. Cell Biol. 112:1199-1203] that drives organelle transport.

Adenosine Triphosphatases↗
PubMed2004

Resonance light scattering spectroscopy study of interaction between gold colloid and thiamazole and its analytical application.

In this paper, we used resonance light scattering (RLS) spectroscopy to study the interaction between thiol-containing pharmaceutical-thiamazole and gold colloid. At pH 5.2, the resonance light scattering spectrum of gold nanoparticles has a maximum peak at 555 nm and the RLS intensity is enhanced by trace amount of thiamazole due to the interaction between thiamazole and gold colloid. The binding of colloidal gold to thiamazole results in ligand-induced aggregation of colloidal gold, which was characterized by RLS spectrum, ultraviolet-visible (UV-Vis) spectrum, and transmission electron microscopy (TEM). Based upon the study, we proposed a highly sensitive, gold colloid-based assay using RLS spectrum to detect pharmaceuticals for the first time. The mechanism of binding interaction between Au colloid and thiamazole was also discussed.

Absorption↗