Anti-corrosion ceramic coatings on the surface of Nd-Fe-B repelling magnets

The results of vacuum-arc deposition of thin ZrO₂coatings to protect the surface of Nd-Fe-B permanent magnets used as repelling devices in orthodontics are presented. The structure, phase composition and mechanical properties of zirconium dioxide films have been investigated by means of SEM, XRD, EDX, XRF and nanoindentation method. It was revealed the formation of polycrystalline ZrO₂ films of monoclinic modification with average grain size 25 nm. The influence of the ZrO₂ coating in terms of its barrier properties for corrosion in quasi-physiological 0.9 NaCl solution has been studied. Electrochemical measurements indicated good barrier properties of the coating on specimens in the physiological solution environment

Synthesis and characterisation of nanocrystalline ZrN PVD coatings on AISI 430 stainless steel

The nanocrystalline films of zirconium nitride have been synthesized using ion-plasma vacuum-arc deposition technique in combination with high-frequency discharge (RF) on AISI 430 stainless steel at 150oC. Structure examinations X-ray fluorescent analysis (XRF), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) with microanalysis (EDS), and transmission electron microscopy (TEM), nanoidentation method – were performed to study phase and chemical composition, surface morphology, microstructure and nanohardness of coatings. The developed technology provided low-temperature coatings synthesis, minimized discharge breakdown decreasing formation of macroparticles (MPs) and allowed to deposit ZrN coatings with hardness variation 26.6…31.5 GPa. It was revealed that ZrN single-phase coatings of cubic modification with finecrystalline grains of 20 nm in size were formed

Peritektični čelici: značajke strukture, tehnologije legiranja i primjene

The article presents analysis of phase transformation characteristics, primary structure formation, alloying technology and usage of steels, which undergo a peritectic transformation during their solidification.U članku se predočuje analiza značajki fazne transformacije, nastanka primarne strukture, tehnologije legiranja i primjene čelika podvrgnutih peritektičkoj transformaciji pri skrućivanju

Plant sulfolipid. II. Mutant study and phosphate deficiency

Study with SQDG-deficient mutants showed that formation of the sulfonic acid precursor, UDP-sulfoquinovose, in higher plants is considered to be catalyzed by the orthologous plant proteins SQD1. The second required plant enzyme, SQD2, is highly similar to glycosyltransferases and it is proposed that this protein represents sulfolipid synthase. The results of recent works have shown that for the stable activity PS II needs the presence of SQDG and that it participates in PS II recovering through some mechanism dependent on light. Under phosphate-limiting conditions a decrease in the content of one acidic lipid (PG) was accompanied by an increase in the content of the other acidic lipid (SQDG), which resulted in the maintenance of a certain level of total acidic lipids of chloroplast membranes

Some aspects of periodontitis pathogenesis in children.

Inflammatory processes in the tissues surrounding tooth root are frequent enough and develop as the direct complication of caries. As acute periodontitis is manifested with grinding toothache and violation of ph­y­sio­logical act of chewing, symptoms of general intoxication, the continuous sluggish chronic periodontitis is harmful and dangerous to the organism as well. It forms the state of chronic оdontogenetic intoxication and chroneosepsis with wrong functioning of some internal organs and body systems. The like complications can cause significant disturbance to the function of kidneys, liver, heart, joints and their treatment without ablating focus of inflammation is often in- effective; this must be taken into account by doctors-interns. However, scanning of the oral cavity by conservative means has its difficulties mostly because of ignoring pathogenesis of such inflammation. That is why activity of ferments of blood dehydrogenases from the periapical tissues of the teeth affected with the chronic periodontitis was studied. The level of succinate dehydrogenase and alpha-glycerophosphate degydrogenase of lymphocytes of 110 schoolchildren aged 13-17 years old was studied. The main group of examined individuals included those of infected with tuber­culousis – 50 individuals, and the control group (60 individuals) – clinically healthy ones without tuberculousis desease. All schoolchildren had 1 or 2 teeth affected with chronic periodontitis of the apical localization. The re­searchers found that a significant inhibition of activity of succinate dehydrogenase and alpha-glycerophosphate degydrogenase ferments occurs in the inflammatory periodontal tissues, which indicates to local immunity decline, and as a consequence, pathogenic bacteria activation. In people infected with tuberculousis these violations were  more developed. Such features of periodontitis pathogenesis must be taken into account when providing a combined treatment

Automated test analysis of main technological modes of stepless transmissions

Предложена методика по комплексной оценке, сравнению альтернативных вариантов и общая идеология автоматизированного конструирования бесступенчатых трансмиссий шахтных дизелевозов. Рассмотрен автоматизированный тестовый анализ основных технологических режимов работы бесступенчатых гидрообъемно-механических или электромеханических трансмиссий.The methodology for integrated evaluation, comparison of alternatives and the general ideology of automated construction of stepless transmissions are offered. The automated test analysis of the main technological modes of stepless hydrovolumetric mechanical or electromechanical transmissions is reviewed

Vascular mechanism in the formation of diclophenac induced gastrotoxicity: the association with the level of hydrogen sulfide

Department of Pharmacology, N. I. Pirogov National Medical University of Vinnitsa, UkraineBackground: Non-steroid anti-inflammatory drugs (NSAIDs)-induced gastrotoxicity arises as a result of imbalance between vasodilator and vasoconstrictor bioregulators. The influence of deficiency and excess of hydrogen sulfide on vascular mechanisms in the formation of NSAIDs-induced gastrotoxicity was investigated. Material and methods: Male nonlinear rats underwent preconditioning with donor of H2S (NaHS) and inhibitor of its synthesis (propargilglycine). Diclophenac sodium was introduced orally (8 mg/kg). In homogenates of rats’ gastric mucosa was evaluated the activity of prostaglandin-H-synthase (PgH-synthase), NO-synthase, content of nitrites and nitrates, H2S and the activity of cystathionine-γ-lyase. In vitro H2S-induced relaxation of mesenteric arteries was measured. Results: Diclophenac sodium decreased cystathionine-γ-lyase enzyme activity, NO-synthase and PGH-synthase (by 17-24%), content of their H2S metabolites and nitrites/nitrates (by 20-22%) in gastric mucosa, and accompanied with the decrease of mesenteric artery sensitivity to vasodilatory action of H2S (EC50 increased to 27.5%). H2S deficiency – increases and excess of H2S – inhibits the negative influence of diclophenac on the production of vasoactive molecules and H2S-induced relaxation of mesenteric arteries. Conclusions: Excess of H2S in organism increases the content of vasoligating molecules and thus can prevent vascular disturbances caused by NSAIDs in rat stomach mucosa

Features of application of stepless hydrovolumetric mechanical transmissions

Наведено основні переваги й недоліки гідрооб’ємно-механічних трансмісій. Проаналізовано кінематичні та функціональні схеми двопотокових гідрооб’ємно‐механічних трансмісій. Доведено, що застосування безступінчастих трансмісій перспективне як на автомобілях, так і на шахтних дизелевозах.The basic advantages and disadvantages hydrovolumetric mechanical transmissions are given. Kinematic and functional scheme of double‐mechanical transmissions are analyzed. It is proved that the use of stepless transmissions is promising as in cars, and on mine diesel locomotives

Algorithm of benchmarking transmissions of transport vehicles

Для бесступенчатых трансмиссий транспортных средств модернизированы и обобщены интегральные стохастические критерии по тяговой динамике, КПД и мощности тепловыделений. Предложен новый интегральный стохастический критерий по топливной экономичности.For the stepless transmissions of transport vehicles modernized and generalized integral stochastic criteria on a hauling dynamics and powers of exotherm. A new stochastic integral criterion is offered for a fuel economy