Peculiarities of formation and growth of nanodispersed intermetallic strengthening inclusions in rapidly-solidified alloys of Al–Mg–Zr–X-system

The paper is devoted to the influence of the fourth element on the microstructure of the rapidly-solidified alloys of the Al–Mg–Zr-system. Alloys were additionally doped with high-melting-point metals Ti, Hf, W, and Nb. In the structure of all samples in the immediate area of the cooled surface, uniformly distributed intermetallic inclusions of several nanometers in size were detected. Such a structure can be represented as a dispersion-strengthened composite. A quantitative metallographic analysis was carried out to quantitatively describe the structure of the obtained particles of the cooled melt. The obtained rapidly-solidified alloys can be described as dispersion-strengthened composite materials with the aluminum-magnesium alloy matrix and the intermetallic particles strengthener. Depending on the alloying component, these particles differ in shape (spheres, plates, agglomerates) and in size (from 200 nm when alloying with Hf and W up to 1.2-1.5 μm with Ti and Nb alloying). The X-ray phase analysis (XPA) showed that in the studied alloys of the Al–5Mg–1.2Zr–(0.5÷2.0)X-system, high cooling rates of melts lead to the formation of new intermetallic compounds that are absent in equilibrium systems. The example of an alloy with hafnium additive shows that an increase in the content of the alloying component (from 0.5 to 2 % by mass) leads to an increase in the volume ratio of intermetallic inclusions (from 5 to 12.8 %). At the same time, their shape and average size remain unchanged. The additional alloying component will improve the mechanical characteristics of aluminum alloys by increasing the recrystallization threshold of a rapidly-solidified alloy

Reasons for unfavorable results of surgical treatment of diaphyzary fractures of bones of the forearm.

The article provides a retrospective analysis of the causes of complications of surgical treatment of diaphyseal fractures of the forearm bones.В статье проводится ретроспективный анализ причин осложнений оперативного лечения диафизарных переломов костей предплечья

Comprehensive approach to improving the efficiency of treatment of purulent diseases of hand

63 patients with phlegmons of a hand of various localization were treated. Patients were divided into 2 groups of observations. The change in the indices of the T-cell link of immunity was revealed. Patients of the study group received immunotropic therapy in combination with the use of ultrasonic cavitation of wounds, and hydroactive wound coatings. The complex of measures used improves the results of treatment of patients with phlegmon.Проведено лечение 63 пациентов с флегмонами кисти различной локализации. Больные были разделены на 2 группы наблюдений. Выявлено изменение показателей Т-клеточного звена иммунитета. Пациенты группы исследования получали иммунотропную терапию в сочетании с использованием ультразвуковой кавитации ран и гидроактивных раневых покрытий. Используемый комплекс мероприятий улучшает результаты лечения больных с флегмонами кисти

Drug Resistant Mycobacterium tuberculosis of the Beijing Genotype Does Not Spread in Sweden

BACKGROUND: Drug resistant (DR) and multi-drug resistant (MDR) tuberculosis (TB) is increasing worldwide. In some parts of the world 10% or more of new TB cases are MDR. The Beijing genotype is a distinct genetic lineage of Mycobacterium tuberculosis, which is distributed worldwide, and has caused large outbreaks of MDR-TB. It has been proposed that certain lineages of M. tuberculosis, such as the Beijing lineage, may have specific adaptive advantages. We have investigated the presence and transmission of DR Beijing strains in the Swedish population. METHODOLOGY/PRINCIPAL FINDINGS: All DR M. tuberculosis complex isolates between 1994 and 2008 were studied. Isolates that were of Beijing genotype were investigated for specific resistance mutations and phylogenetic markers. Seventy (13%) of 536 DR strains were of Beijing genotype. The majority of the patients with Beijing strains were foreign born, and their country of origin reflects the countries where the Beijing genotype is most prevalent. Multidrug-resistance was significantly more common in Beijing strains than in non-Beijing strains. There was a correlation between the Beijing genotype and specific resistance mutations in the katG gene, the mabA-inhA-promotor and the rpoB gene. By a combined use of RD deletions, spoligotyping, IS1547, mutT gene polymorphism and Rv3135 gene analysis the Beijing strains could be divided into 11 genomic sublineages. Of the patients with Beijing strains 28 (41%) were found in altogether 10 clusters (2-5 per cluster), as defined by RFLP IS6110, while 52% of the patients with non-Beijing strains were in clusters. By 24 loci MIRU-VNTR 31 (45%) of the patients with Beijing strains were found in altogether 7 clusters (2-11 per cluster). Contact tracing established possible epidemiological linkage between only two patients with Beijing strains. CONCLUSIONS/SIGNIFICANCE: Although extensive outbreaks with non-Beijing TB strains have occurred in Sweden, Beijing strains have not taken hold, in spite of the proximity to high prevalence countries such as Russia and the Baltic countries. The Beijing sublineages so far introduced in Sweden may not be adapted to spread in the Scandinavian population

Pre-Existing Isoniazid Resistance, but Not the Genotype of Mycobacterium Tuberculosis Drives Rifampicin Resistance Codon Preference in Vitro

Both the probability of a mutation occurring and the ability of the mutant to persist will influence the distribution of mutants that arise in a population. We studied the interaction of these factors for the in vitro selection of rifampicin (RIF)-resistant mutants of Mycobacterium tuberculosis. We characterised two series of spontaneous RIF-resistant in vitro mutants from isoniazid (INH)-sensitive and -resistant laboratory strains and clinical isolates, representing various M. tuberculosis genotypes. The first series were selected from multiple parallel 1 ml cultures and the second from single 10 ml cultures. RIF-resistant mutants were screened by Multiplex Ligation-dependent Probe Amplification (MLPA) or by sequencing the rpoB gene. For all strains the mutation rate for RIF resistance was determined with a fluctuation assay. The most striking observation was a shift towards rpoB-S531L (TCG→TTG) mutations in a panel of laboratory-generated INH-resistant mutants selected from the 10-ml cultures (p<0.001). All tested strains showed similar mutation rates (1.33×10−8 to 2.49×10−7) except one of the laboratory-generated INH mutants with a mutation rate measured at 5.71×10−7, more than 10 times higher than that of the INH susceptible parental strain (5.46–7.44×10−8). No significant, systematic difference in the spectrum of rpoB-mutations between strains of different genotypes was observed. The dramatic shift towards rpoB-S531L in our INH-resistant laboratory mutants suggests that the relative fitness of resistant mutants can dramatically impact the distribution of (subsequent) mutations that accumulate in a M. tuberculosis population, at least in vitro. We conclude that, against specific genetic backgrounds, certain resistance mutations are particularly likely to spread. Molecular screening for these (combinations of) mutations in clinical isolates could rapidly identify these particular pathogenic strains. We therefore recommend that isolates are screened for the distribution of resistance mutations, especially in regions that are highly endemic for (multi)drug resistant tuberculosis

Effect of positive ionisation of inspired air on the response of asthmatic children to exercise.

To evaluate the effect of positive ionisation of inspired air on bronchial reactivity, 12 asthmatic children were twice challenged by exercise in random order. During one test positively ionised air (5-10 X 10(5) ions/cm) was breathed. All challenges were matched in terms of basal lung function and exercise tests were matched in terms of ventilation and respiratory heat loss. Exercise induced asthma was significantly aggravated by exposure to positively ionised air, the postexercise fall in FEV1 (delta FEV1) being 24.7% (SEM and 5.3%) and 35.3% (5%) after the control and ionised air tests respectively (p less than 0.04). It is concluded that positive ionisation aggravates the bronchial response to exercise

VALIDATION OF ANALYTICAL METHOD OF ASSAY OF SERPISTEN IN OINTMENT

In this work are presented the results of analytical method validation of potency assay of serpisten in ointment according to the UF-spectrometry method. A method is validated on such indicators as specificity, range, linearity, trueness and a precision