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PubMed2005

Optical absorption and photoluminescence spectroscopy of the growth of silver nanoparticles.

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.

Journal Article↗
PubMed1988

Genetic polymorphism of plasma alpha 1 B-glycoprotein and transferrin in arctic and silver foxes.

Plasma samples of 235 foxes from 38 complete families (14 of arctic foxes, 21 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by one-dimensional horizontal polyacrylamide gel electrophoresis (PAGE) pH 9.0 followed by general-protein staining of gels. A major postalbumin of fox plasma was identified as alpha 1B-glycoprotein (alpha 1B) by using immunoblotting with antiser m specific to human or pig plasma alpha 1B. Four codominant, autosomal alleles of alpha 1B were found in arctic foxes. Two transferrin (TF) alleles (TfF, TfS) were observed in arctic foxes and two (TfD, Tff) in silver foxes; the TF F type of both of the fox species showed identical electrophoretic mobilities. The arctic foxes showed a high degree of polymorphism for both TF and alpha 1B. The silver foxes showed a scarce polymorphism of TF and were monomorphic for alpha 1B. The arctic fox, silver fox and their hybrids could be clearly differentiated from one another by their plasma protein patterns obtained by the PAGE method.

Alleles↗
PubMed2006

Chemical composition and structure of the microcrystals formed between silver(I) and gamma-hydroxybutyric acid and gamma-hydroxyvaleric acid.

This study examined microcrystals formed by silver with gamma-hydroxybutyric acid (GHB) and gamma-hydroxyvaleric acid (GHV), the five-carbon analog of GHB, in the presence of silver, copper, and lanthanide nitrates. Distinct microcrystals formed with silver (+1) and lanthanum (+3) ions but not with the copper (+2) ions. The crystals formed with GHB were distinctly different than those formed with GHV and in all cases, the drug microcrystals were easily distinguishable from reagent crystals. X-ray diffraction analysis provided definitive structure for the microcrystals. The morphological differences between the silver-GHB and silver-GHV crystals were characterized using simple measurements such as size and angles provided by image recognition software. The utility of the test for casework was demonstrated using spiked beverage samples.

Journal Article↗
PubMed1977

Reproductive ability of an adult female with Silver-Russell syndrome.

An adult female with typical features of Silver-Russell dwarfism gave birth to a viable infant. Despite the abnormalities in sexual development that may be associated with the Silver-Russell syndrome, fertility is not necessarily impaired, at least in females. The growth and development of children with the Silver-Russell syndrome have been studied (Silver, 1964; Tanner et al., 1975). There is, however, virtually no information available about adult patients with this syndrome. It is known that both male and female Silver-Russell dwarfs develop secondary sexual characteristics (Rimoin, 1969; McDowell and Sproles, 1973) but fertility of these patients has not been described previously.

Adult↗
PubMed1990

Effect of nicotine, silver acetate, and ordinary chewing gum in combination with group counselling on smoking cessation.

Four hundred and ninety six smokers participated in a randomised comparison of the effect of silver acetate, nicotine, and ordinary chewing gum on smoking cessation. All were motivated to stop smoking abruptly and all had smoked at least 10 cigarettes a day for at least five years. Side effects and taste acceptability were related to outcome after six months. The participants attended nine meetings over a year, at which lectures, support, and advice about stopping smoking were given. Tobacco abstinence was confirmed by measurement of carbon monoxide in expired air. The chewing gums were used for 12 weeks. After 12 weeks there was a trend towards more abstainers in the nicotine group (59%) than in the silver acetate (50%) and ordinary (45%) chewing gum groups that was not quite significant (p = 0.07). At 26 and 52 weeks the number of cigarette abstainers was similar in the three treatment groups. Subjects in the nicotine chewing gum group had a longer mean time before relapse than those in the silver acetate and ordinary chewing gum groups. Mean success rates for all subjects combined at 12, 26, and 52 weeks were 52.8%, 39.7%, and 23.3%. The side effects of nicotine and silver acetate chewing gum were generally mild and transient, and unimportant except for mouth irritation from silver acetate, which had a negative effect on outcome, and the low taste acceptability of nicotine, which had a strong negative influence on the success rate. The results suggest a short term effect on nicotine chewing gum on smoking cessation, but the abstinence rates after one year were generally disappointing.

Acetates↗
PubMed1989

An immunogold-silver staining method for detection of cell surface antigens in cell smears.

We developed an indirect immunogold-silver staining method for detection of leukocyte cell surface antigens in cell smears. Air-dried and fixed cytocentrifuge preparations or smears of peripheral blood leukocytes were incubated with monoclonal antibodies (MAb) and colloidal gold-labeled secondary antibodies. The preparations were post-fixed and silver enhancement was performed. The smears were counterstained with May-Grunwald-Giemsa and examined in brightfield light microscopy. The morphology of the cells was well preserved. Leukocytes reacting with the MAb showed black granules on their surface membranes. The intense immunostaining and the low background allowed a rapid enumeration of the positive cells. The labeling could be detected with high sensitivity by epipolarization microscopy. This immunogold-silver staining method was used to quantify T- and B-lymphocytes and natural killer cells in buffy coat smears of normal adult blood. These lymphocyte subsets correlated well with those obtained in smears with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) method and with those found by labeling of mononuclear cells in suspension with immunogold-silver staining. This immunogold-silver staining method forms a good alternative to immunoenzyme methods for study of hematologic cells. In addition, it could be a general procedure for detection of cell surface antigens in all kinds of cell smears.

Antibodies, Monoclonal↗
PubMed2006

Activity patterns of South American silver catfish (Rhamdia quelen).

The South American silver catfish (Rhamdia quelen) is a widely distributed species in Central and South America in areas east of the Andes between Venezuela and the northern parts of Argentina. The bottom dwelling species occurs in lakes and reservoirs as well as in rivers. Between June 2000 and December 2001, sixteen silver catfish were tracked during fourteen 24-h cycles in two-hour-intervals, with the aim of investigating daily movements and habitat use. Covered distances varied between 0 m/2 h and 326 m/2 h and the mean distance covered in 2 h was 25.6 m. The mean activity of individual silver catfish varied between 5.6 m/2 h and 81.4 m/2 h. The swimming activity was linearly related to the total fish length. The highest mean swimming activity occurred in the morning and at nightfall. Silver catfish concentrated in three areas of frequent use. All of them were characterized by steep banks providing shelter in the form of rip-rap or large woody debris. Vertically, silver catfish preferred the upper 2 m layer where tracked fish encountered higher temperatures and higher dissolved oxygen concentrations.

Animals↗
PubMed2002

Catalytic determination of traces of silver(I) using the oxidation of Janus Green with peroxodisulfate.

A method for sensitive and selective determination of silver based on the catalytic effect of silver(I) ion on the oxidation of Janus Green by peroxodisulfate is described. o-Phenanthroline is used as an activator. The rate of the decrease in absorbance of Janus Green (at 615 nm) is proportional to the concentration of silver in the range of 0.3-4.0 ng mL(-1) and 4.0-500.0 ng mL(-1). The theoretical limit of detection was 0.25 ng mL(-1). The method is free from most interferences. The method was applied to the determination of silver in plants (the uptake of silver by plants), in photographic solutions, lake water and several synthetic samples.

Journal Article↗
PubMed2002

Silver-selective sensor using an electrode-separated piezoelectric quartz crystal modified with a chitosan derivative.

Silver(I) adsorbed selectively onto a quartz plate modified with N-(2-pyridylmethyl)chitosan in an ammonium chloride buffer solution containing EDTA, and the frequency of the quartz plate increased. It was supposed that the increasing frequency was caused by the desorption of adsorbed water on the chitosan derivative, which was induced from the reaction of silver(I) with the chitosan derivative. The concentration of the buffer, pH, temperature, conductivity and eluent affected the frequency shift resulting from the adsorption of silver(I). The frequency decreased at a conductivity lower than 2.2 mS/cm, and increased with increasing conductivity above this value. The frequency shifts caused by the adsorption of silver(I) were proportional to the concentration over the range 10-80 nM of silver(I), and the correlation coefficient was 0.9969. The detection limit and the relative standard deviation at 50 nM for five times were 6 nM and 3.4%, respectively. The proposed method was simple while showing higher sensitivity and selectivity.

Journal Article↗
PubMed2004

Potentiometric performance of silver ion-selective electrodes based on tridentate Schiff base derivatives.

To examine the directivity for improving the silver ion discrimination ability of a Schiff base, three kinds of tridentate ligands were synthesized and compared with the similar quadridentate ligand as the silver ionophore. Among the Schiff base derivatives tested, 3-(2-pyridylethylimino)-2-butanoneoxime, having one oxime and a pyridine substituent, was found to be the best ionophore for a silver-ion electrode. The electrode based on this derivative exhibited good silver-ion selectivity, -log Kpot(Ag+,K+) = 3.8, comparable to that of a quadridentate Schiff base, N,N'-bis(2'-hydroxyimino-1'-phenylpropyleden)-1,3-propanediamine, reported previously, except for a pseudo Nernstian response (35.6 mV decade(-1)) with a wide silver-ion activity change in the activity change from 5.0 x 10(-7) to 7.9 x 10(-2) mol dm(-3).

Journal Article↗
PubMed1999

[Studies on the antiviral activity of silver sulfathiazole].

Silver sulfathiazole shows strong antibacterial activity and good tolerance after topical application. The aim of the study was to determine the antiviral activity of silver sulfathiazole in tissue culture after incubation of drug and virus. The antiviral activity was measured after various periods of exposure and at different drug concentrations. The results obtained indicate the activity of silver sulfathiazole against Herpesvirus type 1 and type 2. This drug suppresses or completely inactivates the infectivity of virus. The antiviral effect is directly related to concentration of the drug and duration of exposure. At concentration of 10 micrograms/ml it has the highest activity after 30 minutes of exposure, however at a concentration of 20 micrograms/ml it induces a similar effect after 10 minutes. Silver sulfathiazole had antiviral activity similar to that of silver nitrate, while sulfathiazole alone was ineffective.

Antiviral Agents↗
PubMed2005

Class I and Class II silver amalgam and resin composite posterior restorations: teaching approaches in Canadian faculties of dentistry.

A 10-question survey was mailed to the 10 Canadian faculties of dentistry to determine current approaches to teaching undergraduates about silver amalgam and resin composite for posterior restorations in adults and children. Responses were received from all 10 pedodontic programs and from 8 of the 10 operative and restorative programs. The use of silver amalgam and posterior composite for restorations of primary and permanent teeth is covered in the curricula of all dental schools, but the relative emphasis on the 2 materials varies. In the operative and restorative programs, curriculum time devoted to silver amalgam is either greater than or equal to that devoted to posterior composite. Five of the 8 schools reported greater educational emphasis on silver amalgam for the permanent dentition; however, course directors noted that the preference among patients seen in clinics is tending toward composite restorations. Curricula appear designed to educate students about the optimal use of both materials. Requirements for performance of restorations during training generally do not specify the type of material; these requirements range from 60 restorations to 250 surfaces. Five of the 8 schools conduct clinical competency tests with both materials. The responses from the pedodontic programs were more diverse. The proportion of curriculum time devoted to each type of material in these programs ranged from less than 25% to more than 75%. Five schools reported more emphasis on silver amalgam, 3 schools reported equal emphasis, and 2 schools reported more emphasis on posterior composite. No clinical requirements were specified in any of the undergraduate pedodontic programs. Within some of the faculties, there were differences between the operative and restorative program and the pedodontic program with respect to emphasis on different materials for the posterior dentition.

Adult↗
PubMed2005

[A holographic plate silver film-preparation, morphology and SERS activity].

A new method for preparing SERS-active substrate was reported. After being exposed, developed and fixed, the commercially available holographic plate can be used to generate attractive SERS-active silver surface. The obtained silver film was characterized by UV-Vis spectroscopy and scanning electron microscope (SEM) observation. The absorption spectrum locates at around 420 nm with a narrow half-width due to the surface plasmon resonance, which implies that there are silver particles on the prepared substrate with uniform sizes. And the silver particles distribute uniformly anywhere on the holographic plate with a diameter of about 100 nm by SEM observation. Furthermore, the measurements of the SERS spectrum of crystal violet indicate that such substrate has the features of satisfactory reproducibility, long term stability and high SERS activity. The prepared silver film keeps high SERS activity even if it was stored for several months in the air at room temperature.

English Abstract↗
PubMed1980

[Coincidence of Feulgen-achromasia, in situ hybridization and silver banding in four nucleolus organizers of Vicia sativa (author's transl)].

The results of three cytological techniques have been used to clear up the chromosomal locus and function of NOs in a commercial cultivar of Vicia sativa (2n=12) from Rumania. Karyotypic investigations after Feulgen-staining and arrangement of chromosomes in order of decreasing length of the long arm define chromosome I and chromosome III as SAT-chromosomes. The loci of the Feulgen-negative secondary constrictions coincide with those of the grain clusters after in situ rRNA/DNA hybridization and those of silver precipitation after ammoniacal silver staining. The median position of the weak secondary constriction in the long arm of chromosome I coincides with the position of the small grain cluster after in situ hybridization and the small silver dot after silver staining. The submedian position of the strong secondary constriction in the long arm of chromosome III coincides with the position of the big grain cluster and the big silver dot.

Autoradiography↗
PubMed2002

Fully reversible procedure for silver staining improves densitometry of complex mixtures of biopolymers resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Due to its high sensitivity, silver staining is a widely popular method for the revelation of biopolymers separated by both native and denaturing electrophoresis. A step-by-step method for the destaining and restaining of overdeveloped/overloaded silver-stained bands is described that is applicable to both proteins and nucleic acids. The procedure significantly improves densitometric analysis of gels that have been silver stained with either commercial kits or solutions made in-house. The method permits reproducible densitometry of silver-stained gels and allows quantification of both main and minor components in complex mixture of molecules resolved on the same gel slab. All steps may be interrupted and are readily reversible, allowing for facile densitometric analyses and photographic recording under optimized conditions. Furthermore, common artifacts such as differential staining of the two gel surfaces, localized uneven yellow-ochre background, and the presence of fold marks and fingerprints can be easily removed.

Artifacts↗
PubMed1996

A simplified silver diammine method for the staining of nucleic acids in polyacrylamide gels.

High sensitivity and low background, which are the significant features of the procedure of Johansson and Skoog (J. Biochem. Biophys. Methods. 1987, 14, (Suppl.) 33) for silver staining of nucleic acids in polyacrylamide gels, have been improved by excluding ethanol from all solutions and increasing the length of washing steps after sensitisation and staining. Including a fixation step before sensitisation increased the contrast of the bands even at high concentration of nucleic acid, producing a shift in the tone of colour from black to grey instead of gold to yellow bands. This technique is superior in terms of sensitivity and background to a number of other silver staining protocols, three which utilise silver diammine and three which utilise silver nitrate ions.

Ammonia↗
PubMed1991

Fast and sensitive silver staining of DNA in polyacrylamide gels.

The photochemically derived silver stain of nucleic acids in polyacrylamide gels originally described by Merril et al. (1981, Science 211, 1437-1438) was modified to reduce unspecific background staining and increase sensitivity (down to 1 pg/mm2 band cross-section). Detection limits for double-stranded DNA fragments from HaeIII endonuclease digests of phage phi X174 were maintained despite eliminating oxidation pretreatment of fixed gels and reducing silver nitrate concentration. Preexposure to formaldehyde during silver impregnation enhanced sensitivity and the inclusion of the silver-complexing agent sodium thiosulphate in the image developer decreased background staining. Higher formaldehyde concentration during image development resulted in darker bands with good contrast. The procedure almost halves the number of steps, solutions and experimental time required and can be used for the staining of DNA fragments in polyacrylamide gels bound to a polyester backing film by controlling temperature during image development. We have applied this improved staining procedure for the routine analysis of complex DNA profiles generated by DNA amplification fingerprinting (DAF).

Bacteriophages↗
PubMed1989

Quantitative electron microscopic analysis of postnatal development of zinc-positive nerve endings in the rat amygdala using Timm's sulphide silver technique.

The distribution and quantitation of zinc during postnatal development of the rat amygdala were investigated by light and electron microscopy with Timm's sulphide silver method. The adult rat amygdala could be divided into basolateral, basomedial, central, cortical, intercalated, lateral and medial subnuclei on the basis of Timm's plus Toluidine blue staining. Only a very weakly positive Timm's reaction could be observed in newborns, and a positive reaction was seen on the 5th postnatal day. The reaction became stronger with development, and reached adult levels by the 30th postnatal day. Electron microscopically, we investigated the basolateral subnucleus of the amygdala. The electron-dense deposits of silver grains from the Timm's reaction were only seen in nerve fibers endings containing many small clear vesicles. The results are similar to those described for mossy fiber endings in the rat hippocampus and in boutons of other telencephalic structures. The number of deposits of silver grains increased with age, and reached that of the adult between the 20th and 30th postnatal days. A significant increase in the number of silver grains per micron 2 area of the Timm's-positive nerve terminals occurred between the 10th and 20th postnatal days. Based on the available literature, these findings suggest that zinc exists in nerve fiber endings in the rat amygdala and that the amount increases with postnatal age. The findings are consistent with an important role for zinc in synaptic transmission.

Aging↗