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Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).
The results of a multi-nuclear nuclear magnetic resonance (NMR) study of (AgI)x(Ag2O)y(P2O5)1-x-y glasses are reported. Using the two-dimensional variable-angle correlation spectroscopy experiment, the isotropic and anisotropic chemical shift interactions of phosphorus were determined as a function of silver iodide and silver oxide composition. From these measurements we determine the average conformation of the phosphate groups. In addition, the 109Ag NMR spectra were recorded, as a function of both composition and temperature. At high silver oxide concentrations, interaction between the silver and phosphate groups has been detected, but in glasses in the series the (AgPO3)x(AgI)1-x 31P NMR is strikingly independent on the silver iodide composition. The temperature dependence of the silver NMR linewidths in these systems shows clearly the silver mobility, and at lower temperatures no evidence for multiple distinct silver binding sites was observed. The silver chemical shift is strongly dependent on both composition and temperature. The former effect is interpreted in terms of the influence on the chemical shift of binding to oxygen versus iodine.
The differences in the effects of inorganic Se (IV and VI) compounds and seleno-cystine [(CySe)2] on the Te (as Na2TeO3) uptake by the yeast, Saccharomyces cerevisiae, has been studied. Se, Te, Ag, Zn, Fe and Co contents of the cells were measured by instrumental neutron activation analysis. For the determination of the Ag content, the monostandard method was applied as the analytical method. The contents of other elements were determined by comparison with standards having similar amounts of the determined element as the sample. Results obtained show that an antagonist interaction occurs between SeO2 and Te. There was a significant increase in the concentrations of Se and Te when the yeast was incubated in the medium containing (CySe)2 and Te. (CySe)2 markedly increased the Ag content of cells, especially within the first 8 h of incubation. The low level of SeO2 in the medium are the exterior factor which produce an observable increase of the Ag concentration in the cells. The higher level of SeO2 in the medium causes a long-term marked increase in the Ag content of the cells. The uptake yield of Ag also increased in the presence of (NH4)2SeO4 in the medium. The Te supply produced a significant enhancement in the Ag content of the cells during the initial 8 h of incubation. The presence of Se and/or Te in the medium causes change in the intracellular Zn, Fe and Co levels.
The objective of the experiment was to measure the radiation environment inside and outside of the biosatetlite COSMOS 1887. For this purpose, detector packages were built up consisting of plastic detectors and nuclear emulsions having different linear energy transfer (LET) thresholds in particle registration, and thermoluminescence dosimeters (TLD). Particle fluence rates, LET-spectra and absorbed dose are presented. Absorbed dose is measured as a function of shielding depth. The data are compared with those of other missions.
Monocrystalline sheets of AgCl nuclear track detectors, mounted on top of a detector package, covered by a thin light-filter of 15 micrometers-thick Kapton-foil, were flown in the outside facilities of the Biokosmos 8 Mission. The aim of this lay-out was to record low energy protons and heavy ions, including SAA particles, from the unshielded cosmic radiation. The tracks recorded turned out to be strongly faded. The possible reasons, high temperature (>60 degrees C at the detector surface indicated by temperature markers) or too high temporary intensities of the filtered sunlight, are discussed on the basis of simulation experiments. The report briefly describes: (1) Characteristics of the AgCl-detectors. (2) The lay-out of the experiment, postflight handling and results. (3) Simulation experiments on the ground with respect to the observed fading. (4) A new lay-out proposed for a future analogous experiment with AgCl-detectors.
Two layers of AgCl detectors with a total surface of 90 cm2 were flown. Tracks of nuclei, from light (Z>4) up to the heaviest were recorded and could be distinguished by their geometrical trackwidths. The tracks were divided into five groups of atomic numbers, and their abundance was measured. Also the number of surviving nuclear stars was counted. 22.5 cm2 of the detector surface were covered with eggs of Artemia salina. The detectors could be developed without removing the eggs, so that the spots hit could be determined directly. The radiation effect on these eggs is being investigated.
In this work we report a novel method that can monitor in vivo the salt permeation process into a plant Vigna angularis using two Ag/AgCl electrodes. The method is based on the electromotive force (emf) measurement using two Ag/AgCl electrodes, one inserted into the V. angularis pith cavity and the other placed into saline ([NaCl]=1 M) surrounding the roots. Temporary change of emf ranging from 0 to ca. 0.115 V was measured in vivo using the system, and the possible physiological phenomenon during the period was discussed.
Electropolymerization regime of meso-tetrakis(3-methoxy-4-hydroxyphenyl) porphyrin is optimized to yield films possessing both electrocatalytical and permselective properties towards nitric oxide oxidation. The sensor composed of electrochemically oxidized carbon fiber, covered solely with nickel porphyrin derivative layer electropolymerized using our method, is characterized by high selectivity towards nitrite (1:600), ascorbate (1:8000) and dopamine (>1:80), determined by constant potential amperometry at 830 mV (vs. Ag/AgCl). Selectivity for ascorbate and dopamine as well as detection limit for NO (1.5 nM at S/N=3) is 5-10 times better than parameters usually reported for Nafion coated porphyrinic sensors. Nafion coating can further enhance selectivity properties as well as aids to the stability of the sensors' responses.
A screen-printed enzyme electrode based on flavocytochrome P450scc (RfP450scc) for amperometric determination of cholesterol has been developed. A one-step method for RfP450scc immobilization in the presence of glutaraldehyde or by entrapment of enzyme within a hydrogel of agarose is discussed. The sensitivity of the biosensor based on immobilization procedures of flavocytochrome P450scc by glutaric aldehyde is 13.8 nA microM(-1) and the detection limit is 300 microM with a coefficient of linearity 0.98 for cholesterol in the presence of sodium cholate as detergent. The detection limits and the sensitivity of the agarose-based electrode are 155 microM and 6.9 nA microM(-1) with a linearity coefficient of 0.99. For both types of electrodes, the amperometric response to cholesterol in the presence of detergent was rather quick (1.5-2 min).
BACKGROUND: The risk factors for catheter-associated urinary tract infections (CAUTIs) that are associated with catheter care have not been examined in detail by prospective studies or randomised clinical trials. OBJECTIVES: To examine the patterns of catheter care and to identify the CAUTI risk factors associated with catheter care. DESIGN: Prospective observational study. METHODS: Between January and December 2004, 555 adult patients who were catheterised for 3 days in five general hospitals in Japan were surveyed. One researcher collected the following data twice a week: catheter insertion method, catheter management, and signs and symptoms of urinary tract infections. The relative risk exceeding 1 by the Poisson regression were selected for Cox proportional hazard analysis in order to calculate adjusted risks. In addition, expected reductions in the incidence of CAUTIs by elimination of the risk factors were estimated using the population attributable risk percent. RESULTS: The mean duration of catheterisation was 25 days. The overall incidence of CAUTIs was 3.9 cases per 1000-device days; the incidence of CAUTIs ranged from 0.6 to 7.2 cases per 1000-device days among the five hospitals. Only fecal incontinent patients were analysed since they accounted for 94% of the CAUTI cases. In the univariate analysis, the silver-alloy catheter, which contains antimicrobial property, emerged as a potential risk. Since silver-alloy catheters were used in only one hospital, silver-alloy catheter care was compared with that of the other types of catheter, and a significantly higher percentage of inappropriate care was observed. In the final Cox model, two variables remained: 'non-pre-connected closed system (standard system)' (RR 2.35, 95%CI 1.20-4.60, p = 0.013) and 'no daily cleansing of the perineal area' (RR 2.49, 95%CI 1.32-4.69, p = 0.005). The population attributable risk percent suggested that the use of a 'pre-connected closed system' and 'daily cleansing of the perineal area' could reduce the incidence of CAUTIs by nearly 50%. CONCLUSIONS: Our investigation identified fecal incontinence as the major risk factor for CAUTIs in the study population. However, attributable risk percent indicates that the implementation of two basic elements of catheter care could reduce CAUTIs by nearly 50%. The hospital using silver-alloy catheters had the highest CAUTI rates, strongly suggesting the hazards of relying on the antimicrobial property of silver and the resultant laxity in care.
Argyria is a rare skin disease caused by cutaneous deposition of silver granules in the skin as a result of exposure to silver substrate or ingestion of silver salt. This report describes a patient with generalized argyria caused by ingestion of homemade colloidal silver solution. The patient learned about the uses of the silver solution and its preparation at a convention for "natural medicine."
Surface-enhanced Raman scattering (SERS) spectra of four amphiphilic nucleolipids in single-layer Langmuir-Blodgett (LB) films deposited on silver island film substrates from pure water and complementary nucleotide-containing subphase and corresponding powder normal Raman spectra were obtained. The analysis of these spectra indicates that the SERS effect is mainly caused by a charge-transfer mechanism, and only the nucleobase headgroup moieties and complementary bases combined with them through hydrogen bonds, which are directly in contact with the silver island film substrates, could be enhanced. For the amphiphilic nucleolipids with the identical nucleobase headgroups, the SERS spectra of the LB films are similar, implying that the orientations of these nucleobase moieties on the silver substrates are analogous. However, the nucleobase takes different orientations on the silver substrates before and after complementary binding. The nucleobases in the LB films deposited from pure water are nearly lying flat on the silver surface, while the complementary binding pairs transferred from the air/water interface tend to take an end-on orientation on the metal surface.
Due to limitations of the existing preparative methods of hollow nanoparticles by either heating at high temperature (>600 degrees C) or by using strong acid, alkali, or an organic solvent, it was not possible up till now to encapsulate any sensitive organic molecule like enzyme or others inside the cavity of hollow nanoparticles. We have demonstrated a much softer method of preparing hollow silica nanoparticles with horseradish peroxidase (HRP) inside the cavity by synthesizing HRP-doped core-shell silica-coated silver chloride nanoparticles and finally leaching out silver chloride with dilute ammonia at low temperatures. TEM pictures showed the hollow cavity inside the nanoparticles. The enzyme entrapped in these particles was active. The turnover number of HRP entrapped into these hollow particles and dispersed in aqueous buffer (pH 7.2) (k(cat) = 2.56 x 10(6) s(-1)) was found to be less than that of free enzyme in aqueous buffer (k(cat) = 6.133 x 10(7) s(-1)) but higher than that of HRP entrapped in solid-core silica nanoparticles and dispersed in aqueous buffer (k(cat) = 1.05 x 10(5) s(-1)). The result showed that hollow nanoparticles could be prepared using soft chemical methods and sensitive chemicals like active enzyme could be entrapped in the cavities and it retains its activity.
The effect of endotracheal tubes (ETTs) impregnated with chlorhexidine (CHX) and silver carbonate (antiseptic ETTs) against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacter aerogenes [organisms associated with ventilator-associated pneumonia (VAP)], was evaluated in a laboratory airway model. Antiseptic ETTs and control ETTs (unimpregnated) were inserted in culture tubes half-filled with agar media (airway model) previously contaminated at the surface with 10(8) cfu/mL of the selected test organism. After five days of incubation, bacterial colony counts on all ETT segments were determined. Swabs of proximal and distal ends of the agar tract in antiseptic and control models were subcultured. The initial and residual CHX levels, (five days post-implantation in the model) were determined. Cultures of antiseptic ETTs revealed colonization by the tested pathogens ranging from 1-100 cfu/tube, compared with approximately 10(6) cfu/tube for the control ETTs (P < 0.001). Subcultures from proximal and distal ends of the agar tract showed minimal or no growth in the antiseptic ETTs compared with the control ETTs (P < 0.001). The amount of CHX retained in the antiseptic ETTs after five days of implantation was an average of 45% of the initial level. Antiseptic ETTs prevented bacterial colonization in the airway model and also retained significant amounts of the antiseptic. These results indicate that the effectiveness of antiseptic-impregnated ETTs in preventing the growth of bacterial pathogens associated with VAP may vary with different organisms.
Ionic silver exhibits antimicrobial activity against a broad range of micro-organisms. As a consequence, silver is included in many commercially available healthcare products. The use of silver is increasing rapidly in the field of wound care, and a wide variety of silver-containing dressings are now commonplace (e.g. Hydrofiber dressing, polyurethane foams and gauzes). However, concerns associated with the overuse of silver and the consequent emergence of bacterial resistance are being raised. The current understanding of the biochemical and molecular basis behind silver resistance has been documented since 1998. Despite the sporadic evidence of bacterial resistance to silver, there have been very few studies undertaken and documented to ascertain its prevalence. The risks of antibacterial resistance developing from the use of biocides may well have been overstated. It is proposed that hygiene should be emphasized and targeted towards those applications that have demonstrable benefits in wound care. It is the purpose of this review to assess the likelihood of widespread resistance to silver and the potential for silver to induce cross-resistance to antibiotics, in light of its increasing usage within the healthcare setting.
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Catheter-associated urinary tract infections (CAUTIs) are a common occurrence and are associated with increased patient morbidity and mortality. In addition, they delay patient discharge from hospital, substantially increase hospital costs and promote the emergence of resistant organisms. Any intervention resulting in a decrease in the incidence of CAUTIs would have a significant impact on patient quality of life and hospital costs. By reviewing the current literature, it can be seen that the use of silver-alloy-coated hydrogel catheters can reduce CAUTIs by up to 45%. Despite reducing CAUTIs in most hospital situations, the greatest reduction is seen in postoperative patients, intensive care unit patients and burns patients.
AG3 (AYSSGAPPMPPF) is an inorganic-binding peptide that specifically and selectively binds to silver demonstrated by phage display library according to the Stone group. In our experiment, synthesized silver-binding peptide AG3 was immobilized on the surface of protonated poly(ethylene terephthalate) (PET) film which was prepared for biomimetic synthesis silver particles in vitro. Silver crystallites formatted on the surface of AG3-PET film showed various shapes and was 1-4 microm in size. In addition to hexagonal and triangular crystallite, a silver crystallite presents a cubical shape that has seldom been reported in the literatures so far. With comparison of the control and silver nitrate salt, the surface energy of the silver particles on AG3-PET film surface XPS analysis suggested that Ag+ was being reduced to Ag0 in the reaction. Moreover, CD spectrum revealed that the secondary structure of AG3 peptide in solution had a little change before and after binding silver.