Facile Synthesis of Stable Cerium Dioxide Sols in Nonpolar Solvents.

A method is proposed for the preparation of stable sols of nanocrystalline cerium dioxide in nonpolar solvents, based on surface modification of CeO nanoparticles obtained by thermal hydrolysis of concentrated aqueous solutions of ammonium cerium(IV) nitrate with residues of 2-ethylhexanoic and octanoic acids. The synthesis was carried out at temperatures below 100 °C and did not require the use of expensive and toxic reagents. An assessment of the radical-scavenging properties of the obtained sols using the superoxide anion-radical neutralization model revealed that they demonstrate notable antioxidant activity.

Strong Antibacterial Properties of Cotton Fabrics Coated with Ceria Nanoparticles under High-Power Ultrasound.

Flexible materials, such as fabric, paper and plastic, with nanoscale particles that possess antimicrobial properties have a significant potential for the use in the healthcare sector and many other areas. The development of new antimicrobial coating formulations is an urgent topic, as such materials could reduce the risk of infection in hospitals and everyday life. To select the optimal composition, a comprehensive analysis that takes into account all the advantages and disadvantages in each specific case must be performed.

[The color analysis of nanocomposite material before and after exposure to whitening toothpastes using a portable spectrophotometer].

Purpose: To determine the effect of whitening toothpastes on the color of a nanocomposite material using a spectrophotometer.

Material And Methods: The study involved 50 samples from nanocomposite restoration material which were exposed under laboratory conditions to brushing with one of 4 types of toothpastes (control with no bleaching agents, peroxide paste with carbamide, abrasive and enzyme-based pastes). Using the parameters a, b and L obtained by spectrophotometry, delta E (ΔE) value was calculated.

Formation and interconversion of CCN and CNC radicals resulting from the radiation-induced decomposition of acetonitrile in solid noble gas matrices.

Acetonitrile and the species resulting from its dehydrogenation play an important role in the radiation-induced evolution of organic matter in the space environment. In this work, we report on FTIR spectroscopic studies of the degradation of isolated CH3CN and CD3CN molecules induced by prolonged X-ray irradiation in solid noble gas matrices at 5 K. The principal products observed at high conversion degree of the parent acetonitrile molecules (70-90%) are CCN and CNC radicals, which result from prompt or two-step dehydrogenation of the corresponding precursors, H2CN and CH2NC radicals, respectively.

Characterization of the HCNCO complex and its radiation-induced transformation to HNCCO in cold media: an experimental and theoretical investigation.

The HCNCO complex and its X-ray induced transformation to HNCCO in solid noble gas (Ng) matrices (Ng = Ne, Ar, Kr, Xe) was first characterized by matrix isolation FTIR spectroscopy at 5 K. The HCNCO complex was obtained by deposition of HCN/CO/Ng gaseous mixtures. The assignment was based on extensive quantum chemical calculations at the CCSD(T) level of theory.

Matrix isolation and ab initio study on HCN/CO system and its radiation-induced transformations: Spectroscopic evidence for HCN⋯CO and trans-HCNH⋯CO complexes.

Spectroscopic characteristics and X-ray induced transformations of the HCN⋯CO complex in solid Ar and Kr matrices were studied by FTIR spectroscopy and ab initio calculations at the CCSD(T) level. The complex was prepared by deposition of the HCN/CO/Ng gas mixtures (Ng = Ar or Kr). The comparison of the experiment and calculations prove formation of a linear, H-bonded NCH⋯OCO complex with a substantial red shift of the C-H stretching band and a blue shift of the H-C-N bending band in respect to the monomer.

[Study on the influence of whitening toothpastes on the nanocomposite material surface].

The influence of whitening toothpastes on the surface of nanocomposite dental restorative materials (24 samples divided in 3 groups according to type of toothpaste used) was studied using optical profilometry. The most significant changes on the surface roughness of the material caused abrasive whitening toothpaste in comparison to enzymes-based paste. Selection and use of whitening toothpastes in patients with dental restorations must be carried out under dentist's supervision.

Measles in Minsk, Belarus, 2001-2003: clinical, virological and serological parameters.

Background: A number of cases of measles have been reported in the Republic of Belarus despite vaccine coverage of 98%. The absence of information on measles virus genotypes circulating in the Republic of Belarus has made it difficult to asses the situation.

Objectives: The purpose of this study was to isolate and sequence measles virus strains from clinical cases in Minsk, Belarus, and to estimate the role of vaccine failure in those cases.

[Virological and immunological indices in patients with multiple sclerosis].

The level of specific antibodies to viruses of measles, parotitis, type-6 herpes, Epstein-Barr, tick-borne encephalitis and Borrelia burgdorferi as well as presence of genetic samples and antigens of the above infectious antigens were studied in patients with multiple sclerosis (MS). The cytokines Th1 and Th2 parameters were investigated in blood serum of patients at different MS stages. The titer of antibodies to measles virus was noted to be increasing in MS patients with age and disease aggravation.

Acute infectious mononucleosis and coincidental measles virus infection.

Background: Both Epstein-Barr and measles viruses (MV) cause immune suppression, and the association of the two viruses is evaluated as life threatening. The cell immune impairment caused by simultaneous Epstein-Barr and measles viral infections was responsible for the complicated course of the disease in all described previously reports and for unfavorable outcomes in most of the cases. Timely diagnosis of coincidental viral infections could be a useful predictor for the clinical course and complications.

[Cloning and identification of an Agrobacterium radiobacter 5D-1 chromosome fragment involved in control of nitrogen metabolism, biosynthesis of indolylacetic acid and replication of ColE1 plasmids].

Pleiotropic chromosomal mutations were earlier identified in saprophytic associative bacterium Agrobacterium radiobacter 5D-1. The mutations changed nitrogen metabolism, disturbed synthesis of indolylacetic acid (IAA), and conferred the ability to sustain replication of ColE1 plasmid derivatives, which are not normally maintained in bacteria other than Escherichia. The mutations were designated Nr (Nitrogen metabolism) and assigned to a single cluster on an A.

[Genetic control of processes of bacterial interactions with plants in associations].

This review is devoted to the mechanisms and genetic control of processes underlying the formation and efficiency of associative relationships between bacteria and plants. The role of different polysaccharides and cellular fibrils in the appearance of associative relations and the biosynthetic pathway of these compounds and structures is considered. The molecular mechanisms of bacterial systems responsible for stimulating plant growth and development--nitrogen fixation and synthesis of a plant hormone, indoleacetic acid--are presented.

[Bacterial conjugative transposons].

Data on conjugative transposons of Gram-positive and Gram-negative bacteria are reviewed. Their organization and the mechanism of their transposition and mobilization of other replicons are considered. The transposition regulation by tetracycline and the role of conjugative transposons in bacterial gene transfer are briefly discussed.

[Mutants of the phototrophic bacteria Rhodobacter sphaeroides sensitive to the mutagenic action of long-wave ultraviolet light].

The mutagenic action of near ultraviolet (NUV, greater than or equal to 280) nm) on purple phototrophic soil bacteria Rhodobacter sphaeroides: wild strain 2R and 12 mutants obtained earlier sensitive to UV derivates (UVS) was investigated. The mutagenic action of NUV was measured by induction of resistance to tetracycline (Tet) and nalidixic acid (Nal) and reversion of pigment mutants to wild-type phenotype. The NUV light induces the mutations of resistance to Nal and Tet in wild-type strain 2R; the UVS mutants differed greatly in their NUV-induced mutability.

[Mobilization of the pACYC184 plasmid by hybrid pAS8-121 delta plasmids in Escherichia coli cells].

The plasmid pACYC184 is shown to be mobilized for conjugal transfer in Escherichia coli cells by the deleted (Tn7-TcR) derivatives of the hybrid conjugative plasmid pAS8-121 (RP4-Co1E1). Both the mobilized and mobilizing plasmids are autonomously inherited by the recipient cells when the mobilizing plasmid carries single copy of IS8 (the plasmid pAS8-121 delta 16). Cointegrates pAS8-121 delta 16D:: ::pACYC184 are found in the recipient cells with pACYC184 being inserted between two repeats of IS8 if the derivate plasmid pAS8-121 delta 16D having the duplication of IS8 is used to mobilize pACYC184 for conjugal transfer.

[Selective method of isolating mutants sensitive to ultraviolet radiation from a culture of Rhodopseudomonas sphaeroides].

The method of penicillin selection used after UV-irradiation (lambda = 254 nm) allows one to select UV-sensitive mutants (uvs-mutants) of the phototrophous bacterium Rhodopseudomonas sphaeroides induced by nitrosomethylurea with an effectiveness greater by an order of magnitude. Over 30% of the uvs-mutants obtained using this method had an elevated sensitivity not only to far-UV (F-UV, lambda = 254 nm) but also to near-UV (N-UV, lambda greater than 280 nm) UV-irradiation. No correlation was found in the degree of sensitivity to F-UV and N-UV-irradiation of the uvs-mutants.

[Variants of the plasmid pAS8 delta with increased frequency of integration into Rhodopseudomonas sphaeroides chromosome--the result of IS8-element duplication].

The possible participation of IS8 and IS elements of Rhodopseudomonas sphaeroides in cointegrate formation by chromosome of the purple bacterium and plasmid pAS8-121 delta has been studied. The plasmid derivatives having deleted Tn7 have been studied. Plasmid integration into the chromosome of the purple bacterium is shown to be mediated by IS8 element of the plasmid.

[Inheritance of hybrid plasmid pAS*-21 by cells of the purple phototropic nitrogen-fixing bacterium Rhodopseudomonas sphaeroides].

Clones of purple nitrogenfixing prototrophic bacterium Rhodopseudomonas sphaeroides carrying an incertion into the chromosome of the hybrid pAS8-121 (RP4-ColE1 (repA::Tn7] plasmid were analysed. It is revealed that plasmid integration could be due to both Tn7 and other migrating elements (IS8 and possibly, to resident migrating elements of purple bacteria). The plasmid pAS 8-121 can be autonomously transferred from the cointegrate state into Escherichia coli K-12; the plasmid is not inherited autonomously in cells of the purple bacterium.

[Lethal and mutagenic action of solar radiation on model microbiological test systems].

Lethal, mutagenic and recombonogenic action of the solar radiation on the model microorganisms--phage T4, bacteria Escherichia coli and ascomycet Aspergillus nidulans--has been studied. A considerable lethal effect of the solar radiation on phage T4 and E. coli was found.

[Conjugation in Rhodopseudomonas sphaeroides mediated by R plasmids].

Plasmids R68.45, RP4, RP4::Mu cts62, RP1ts::Tn10, RP1ts::Tn9, Rts1 and RP41 were transferred into cells of photosynthetic nitrogen-fixation bacterium Rhodopseudomonas sphaeroides from Escherichia coli and Pseudomonas aeruginosa. The transfer of plasmids occurred with high frequency of 10(-1) to 10(-2) per donor cell in all cases.

[Genetic control of recombination processes in Aspergillus nidulans. IV. The effect of uvs mutations on the frequency of spontaneous and nitrosomethylurea-induced intragenic mitotic recombination].

Effects of three uvs mutations were studied on spontaneous and nitrosomethyl-induced intragenic mitotic segregation in the methA region of the chromosome II in Aspergillus diploids homozygous for uvs and heteroallelic for methA mutation. The reversion frequencies of methA alleles in parent haploid strains were also determined. All the mutations increased the frequency of spontaneous and decreased that of induced intragenic mitotic recombination.