120 research outputs found
Terapeutiliste harjutuste ja manuaalsete võtete kasutamine lülisamba kaelapiirkonna radikulopaatia ravis = Use of the therapeutic exercises and manual techniques in treatment of cervical radiculopathy
https://www.ester.ee/record=b5348243*es
Perspectives of Single-Wall Carbon Nanotube Production in the Arc Discharge Process
Single-wall carbon nanotubes (SWNTs) promise wide applications in many technical fields. As a result purified SWNT material is sold now on the West market at more than $1000 per 1 gram. Thus developing an effective technology for SWNTs production rises to a very important scientific problem. The perspectives of three existing methods providing raw material in the technology of SWNT production have been analyzed. They are i) pulsed laser evaporation of graphite/metal composites, ii) evaporation of graphite electrodes with metal content in the arc discharge process, and iii) catalytic decomposition of the mixture of CO and metal carbonyl catalyst precursor. The observed dynamics of SWNT market points to replacing the laser method of SWNTs production by the arc process. The conclusion has been made that the technology based on the arc process will be the major one for the fabrication of purified SWNTs at least for the next five years. A reliable estimation of a low price limit of SWNTs was derived from a comparison of two technologies based on the arc discharge process: the first one is the production of SWNTs and the second one is the production of a fullerene mixture С60 + С70. The main conclusion was made that the price of purified SWNTs should always be more by 2-3 times the price of fullerene mixture. The parameters of a lab-scale technology for the production of purified SWNTs are listed. A large-scale application of the developed technology is expected to reduce the price of purified SWNTs by approximately ten times. The methods now employed for the characterization of products containing SWNTs are briefly observed. It is concluded that electron microscopy, thermogravimetric analysis, absorption and Raman spectroscopy, measurement of the specific surface aria, optical microscopy - each in separation is not enough for extensive characterization of a sample containing SWNTs, and all these methods should be used together
Miniature Arcs for Synthesis of Carbon Nanotubes in Microgravity
Although many methods are available for producing single-walled carbon nanotubes (SWNTs), the conventional carbon arc process remains the most popular due to its simplicity and large production rate. In the carbon arc, SWNTs are catalytically synthesized by rapidly evaporating a graphite anode impregnated with NiN metal catalyst from which the nanotubes grow in an inert atmosphere. However, high temperatures inside the carbon arc generate strong buoyancy driven convection, and it is hypothesized that the non-uniform environment created by this flow has a large effect on the growth and morphology of the SWNTs. To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was developed to synthesize SWNTs in a microgravity environment substantially free from these strong convective flows. The reactor was operated for either 2.2 or 5 seconds during free-fall in the drop towers at the NASA Glenn Research Center. Two apparatus designs differing mainly in their production rate and power capacity were investigated. The first consisted of a miniaturized carbon arc employing a 1 mm diameter graphite anode and powered by a 0.54 F capacitor bank charged to 65 V. The second, larger apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5 second drop. Initial results indicated that transient heating is a very large effect in the short-duration drop tower carbon arcs, and thermal equilibrium of the arc plasma, buffer gas, and apparatus was not attained during the short microgravity periods. In addition, removal of the buoyant convection by the microgravity now allowed clear observation of large jets of evaporated carbon vapor streaming from the anode and mixing with the inert buffer gas. The initial mixing of these jets with the cold buffer gas combined with the thermal transient made it difficult to establish a uniform high temperature environment around the arc in the 2.1 to 5 second microgravity time interval, and even with a very high-powered arc, the arc region was cooler than in continuously operated arcs. Despite these difficulties, the miniature arc produced SWNTs in microgravity. However, given the large thermal transient to overcome, no dramatic difference in sample yield or composition was noted between normal gravity and q2-,andL%econd long microgravity runs
The inner wind of IRC+10216 revisited: New exotic chemistry and diagnostic for dust condensation in carbon stars
Aims. We model the chemistry of the inner wind of the carbon star IRC+10216
and consider the effect of periodic shocks induced by the stellar pulsation on
the gas to follow the non-equilibrium chemistry in the shocked gas layers. We
consider a very complete set of chemical families, including hydrocarbons and
aromatics, hydrides, halogens and phosphorous-bearing species. Derived
abundances are compared to the latest observational data from large surveys and
Herschel. Results. The shocks induce a non-equilibrium chemistry in the dust
formation zone of IRC+10216 where the collision destruction of CO in the
post-shock gas triggers the formation of O-bearing species (H2O, SiO). Most of
the modelled abundances agree very well with the latest values derived from
Herschel data on IRC+10216. Hydrides form a family of abundant species that are
expelled into the intermediate envelope. In particular, HF traps all the atomic
fluorine in the dust formation zone. Halogens are also abundant and their
chemistry is independent of the C/O ratio of the star. Therefore, HCl and other
Cl-bearing species should also be present in the inner wind of O-rich AGB or
supergiant stars. We identify a specific region ranging from 2.5 R* to 4 R*,
where polycyclic aromatic hydrocarbons form and grow. The estimated carbon
dust-to-gas mass ratio derived from the mass of aromatics ranges from 1.2 x
10^(-3) to 5.8 x 10^{-3} and agrees well with existing observational values.
The aromatic formation region is located outside hot layers where SiC2 is
produced as a bi-product of silicon carbide dust synthesis. Finally, we predict
that some molecular lines will show flux variation with pulsation phase and
time (e.g., H2O) while other species will not (e.g., CO). These variations
merely reflect the non-equilibrium chemistry that destroys and reforms
molecules over a pulsation period in the shocked gas of the dust formation
zone.Comment: 15 pages, 10 figures. Accepted for publication in Astronomy &
Astrophysic
Патогенез опущения влагалища с формированием ректоцеле
To carry out a systematic analysis of the data available in the modern literature on the pathogenesis of the formation of vaginal prolapse with the formation of rectocele rectum. The failure of the pelvic floor, namely its posterior compartment with the formation of a rectocele against the background of the lowering of the posterior vaginal wall, continues to be one of the most common gynecological diseases. This article presents an analysis of current literature data on the pathogenesis of pelvic organ prolapse with the formation of rectocele. Analyzing the above-mentioned data, it can be noted that the research data of recent years have significantly expanded the understanding of the etiology and pathogenesis of pelvic organ prolapse in its posterior compartment. However, the issues of etiology and pathogenesis of genital prolapse in patients of reproductive age, the role of individual risk factors and their combinations, pathogenetic mechanisms of development are still far from being resolved. Unfortunately, none of the above theories fully explains all the reasons for the formation of pelvic organ prolapse in its posterior compartment.Проведен систематический анализ данных, имеющихся в современной литературе, относительно патогенеза формирования опущения влагалища с формиро-
ванием ректоцеле. Несостоятельность тазового дна, а именно заднего компартмента с формированием ректоцеле на фоне опущения задней стенки влагалища,
продолжает оставаться одним из наиболее распространенных гинекологических заболеваний. В статье представлен анализ современных данных литературы о
патогенезе пролапса тазовых органов (ПТО) с формированием ректоцеле. Исследования последних лет заметно расширили представления об этиологии и пато-
генезе ПТО в его заднем компартменте. Однако вопросы этиологии и патогенеза генитального пролапса у пациенток репродуктивного возраста, роли отдельных
факторов риска и их сочетаний, патогенетические механизмы развития все еще далеки от окончательного решения. К сожалению, ни одна из существующих
теорий полностью не объясняет все причины формирования ПТО в его заднем компартменте
САХАРНЫЙ ДИАБЕТ И ТРОМБОЭМБОЛИЯ ЛЕГОЧНОЙ АРТЕРИИ
Purpose. The aim of the study is to analyze characteristics and the clinical course of pulmonary embolism in patients with diabetes on the basis of the Pulmonary Embolism Register (PE) of deaths inTomskhospitals between 2003 and 2011.Materials and methods. We studied the autopsy reports and medical records of all patients (712 cases) diagnosed with pulmonary embolism anteand/or postmortem, died between 2003 and 2010. Diabetes mellitus was diagnosed in 141 patients and all of them had moderately severe course of the disease or were sub-or decompensated. 28.57% had a high body mass as well: 31,59 + 8,36 kg/m2 . The ratio of medical to surgical patients was 2.1 : 1.Results. All patients with diabetes were hospitalized on an emergency basis. 31 patients (21,6 %) stayed in hospital less than a day, so blood clots – the sources of thromboembolism, were formed at home, outside of hospital. The major source of thromboembolism was inferior vena cava branches. At the same time, 31,4 % diabetic patients had thrombi in the right chambers of the heart. Anticoagulants were used in 16,4 % of cases to prevent thromboembolism.Conclusion. The importance of type 2 diabetes mellitus as a risk factor for thromboembolic complications has been until now underestimated both at the outpatient and hospital stages. Цель. По данным госпитального Регистра тромбоэмболии легочной артерии (ТЭЛА) проанализировать варианты ее течения у пациентов с сахарным диабетом.Материалы и методы. Изучены протоколы вскрытий и историй болезни пациентов (712 случаев) с диагностированной прижизненно и/или посмертно ТЭЛА среди умерших в стационарах Томска. Сахарный диабет выявлен у 141 больного и у всех имел среднетяжелое или тяжелое течение, находился в стадии субили декомпенсации, у 28,57 % сопровождался повышенной массой тела. Соотношение «терапевтических» и «хирургических» пациентов составило 2,2 : 1.Результаты. Все пациенты с диабетом госпитализировались в экстренном порядке; 31 пациент (21,6 %) находился в стационаре менее суток, т. е. тромбообразование в местах – источниках тромбоэмболии у них происходило в домашних условиях вне стационара. Ведущим источником тромбоэмболии были ветви нижней полой вены, в том числе вены культи нижней конечности. В 31,4 % местом первичного тромбообразования у пациентов с сахарным диабетом были правые камеры сердца. Профилактические мероприятия в отношении ТЭЛА в виде применения антикоагулянтов использовались в 16,4 % случаев.Заключение. Значимость сахарного диабета 2-го типа как фактора риска развития тромбоэмболических осложнений до настоящего времени недооценивается как на амбулаторном, так и госпитальном этапе.
Chemically activated reactions on the C7H5 energy surface: propargyl + diacetylene, i-C5H3 + acetylene, and n-C5H3 + acetylene
Polycaproamide Modified by Single-Walled Carbon Nanotubes as Protective Coating for Optical Fiber
Mitochondrion as a Target of Astaxanthin Therapy in Heart Failure
Mitochondria are considered to be important organelles in the cell and play a key role in the physiological function of the heart, as well as in the pathogenesis and development of various heart diseases. Under certain pathological conditions, such as cardiovascular diseases, stroke, traumatic brain injury, neurodegenerative diseases, muscular dystrophy, etc., mitochondrial permeability transition pore (mPTP) is formed and opened, which can lead to dysfunction of mitochondria and subsequently to cell death. This review summarizes the results of studies carried out by our group of the effect of astaxanthin (AST) on the functional state of rat heart mitochondria upon direct addition of AST to isolated mitochondria and upon chronic administration of AST under conditions of mPTP opening. It was shown that AST exerted a protective effect under all conditions. In addition, AST treatment was found to prevent isoproterenol-induced oxidative damage to mitochondria and increase mitochondrial efficiency. AST, a ketocarotenoid, may be a potential mitochondrial target in therapy for pathological conditions associated with oxidative damage and mitochondrial dysfunction, and may be a potential mitochondrial target in therapy for pathological conditions
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