Low-filled suspensions of α-chitin nanorods for electrorheological applications.

Highly anisometric α-chitin nanoparticles isolated by TEMPO-oxidation were investigated as filler for electrorheological fluids. The dimensions of rod-like particles were determined by AFM and cryo-TEM methods. The rheological behavior of α-chitin nanoparticles in polydimethylsiloxane changes from viscous to elastic under electric field. The yield stress reaches about 220 Pa at 7 kV/mm for 1.0 wt% fluid. Despite the nanosize of particles, the suspensions sedimentation ratio was found to be low (~23%). The electrorheological behavior of the fluids was discussed in terms of the Mason numbers. The stability of fluids response under switching electric field was shown. The activation energy of polarization processes in suspensions was calculated as 58 ± 2 and 64 ± 1 kJ/mol for 0.5 and 1.0 wt% filler content from the impedance spectra. The high aspect ratio (~70) and dielectric permittivity result in high electrorheological activity of α-chitin suspensions at extremely low concentrations (≤1.0 wt%).

[Diagnostic meningococcal sera and their quality]. / Diagnosticheskie meningokokkovye syvorotki i ikh kachestvo.

The findings evidence that preparation of highly active specific meningococcal sera depends on the selection of production strains and reference cultures for the assessment of their conformity to technological requirements. Meningococcal cultures selection conditions may be unified if standard immune sera are developed, characterized by stable titres of antibodies to group capsule antigens. Employment of such sera will improve the quality of commercial agglutinating sera.

[Pneumococcal serotypes in children with acute and chronic inflammatory diseases of the lungs and in healthy children]. / Serotipy pnevmokokka u detei s ostrymi i khronicheskimi vospalitel'nymi zabolevaniiami legkikh i u zdorovykh.

The serotyping of 350 Streptococcus pneumoniae strains isolated from patients with acute and chronic diseases of the respiratory organs and from healthy children was carried out with the use of the agglutination test. 145 pleural fluid samples were tested for the presence of the pneumococcal antigen and its K-type. The prevailing pneumococcal serotypes were 6, 1, 19, 12 and 9 in acute pneumonia and 6, 19, 42, 3 and 12 in chronic pneumonia, including, respectively, 64.8% and 62% of all typed strains. Cases of pneumonia with complications in the form of pleuritis were mostly induced by serotypes 3, 1, 12 and 14, while in the destructive forms of pneumonia K-types 3, 14, 9 and 12 were isolated. Examinations of healthy pre-school children have shown 16.1% of them to be transitory pneumococcus carriers. Multiple biological examinations carried out during 1.5 years revealed that in this period 42.4% of the children were pneumococcus carriers.

[Incidence of staphylococcal carriage in pregnant women]. / Rasprostranenie stafilokokkovogo nositel'stva u beremennykh.

In 1,494 pregnant women (on weeks 32-36) staphylococcal carriership was studied. One-third of the women under investigation were found to be carriers, their bacterial discharge increasing in spring and summer. The isolated strains proved to be polyresistant to antibiotics and belonged to epidemic strains. About a half of Staphylococcus aureus strains could not be identified with the use of the international set of phages.

[Immunological characteristics of the protein antigens of the family Neisseriaceae. II. The importance of an immunochemical analysis of the protein complexes for a study of taxonomy problems]. / Immunologicheskaia kharakteristika belkovykh antigenov semeistva Neisseriaceae. Soobshchenie II. Znachenie immunokhimicheskogo analiza belkovykh kompleksov dlia izucheniia voprosov taksonomii.

The study of antigenic interrelations in the family Neisseriaceae resulted in the isolation of 2 main immunologically separated variants of protein complexes: the first variant was characteristic of nonpathogenic and pathogenic species of the genus Neisseria as well as of 7 taxonomically undefined Neisseria species (N. lactamicus, N. cuniculi, N. ellongata, N. ovis, N. animalis, N. cinerea, N. canis) and Gemella haemolysans; the second variant was represented by the genera Branhamella and Acinetobacter. N. caviae and 3 out of 14 Neisseria strains of undefined species had no common antigens with the genera Neisseria and Branhamella. The importance of the immunotyping of protein complexes for studying the problems connected with the taxonomy of the family Neisseriaceae was considered.

[Assessment of the condition of the population of gonococcal cultures]. / Otsenka sostoianiia populiatsii gonokokkovykh kul'tur

Application of the method of oblique illumination permitted to reveal nonhomogeneousness of the cultures isolated from the patients with a different (acute and torpid) course of the disease. Passage of the freshly-isolated cultures on the nutrient media led to the appearance of mutants characterized by the fluorescence of the third type which also characterized all the 48 museum cultures stored for a long time on the nutrient media. The method suggested permits not only to evaluate the gonococcal cultures condition but also to carry out their directed selection.

[Use of the oblique illumination method for characterizing N. meningitidis cultures]. / Primenenie metoda kosogo osveshcheniia dlia kharakteristki kul'tur N. meningitidis

The authors used the method of oblique illumination for detection of the state of the population of meningococcus cultures. In studying 48 strains there were revealed three types of fluorescence of the colonies: bright orange with a transition into greenish-light blue along the lower margin (the I type), bright light blue with a narrow orange or green upper margin (the II type) and greyish-light blue colonies (the III type). The type of fluorescence was not associated with the sero-group specificity. Populations of meningococcus cultures, depending on conditions and duration of growth on the nutrient medium could consist both of the colonies with the same type of fluorescence, and also represent a combination of colonies with a different type of fluorescence. The colonies of the I and II types of fluorescence had marked group specificity, but mutation occurred during passage and the III type of fluorescence formed with a loss of serological specificity. Continuous selection of the colonies of the I and the II types of fluorescence permitted to preserve the population with specific properties necessary for production of diagnostic and vaccine preparations for a long time.

[Isolation and identification of Neisseria in bronchial asthma]. / Vydelenie i identifikatsiia neisserii pri bronkhial'noi astme

A study was made of 29 strains of neisseria isolated from the mucosa of the pharynx and the bronchi of patients suffering from infectious-allergic bronchial asthma of different severity. Comparison of the strains by 22 tests (including the assessment of the morphological, biochemical and other signs) permitted to establish the species of neisseria with some probability. The species reference was determined in 23 cultures. N. perflava was isolated in 10 cases, N. subflava--in 6, N. flava--in 3 cases and N. sicca--in 4 cases, 2 strains corresponded to apigmentary N. cinerea. The species was not established in 4 cultures. There was found no connection between a definite microbial association and the species of neisseria and the severity of the disease. Pigment species of neisseria should be tested as diagnostic allergens.