Character of electron reflection at a normal metal-Peierls semiconductor boundary

The reflection of electrons incident from a normal metal on the boundary of the metal with a quasi-one-dimensional conductor containing a charge-density wave (CDW) is investigated theoretically. It is shown that the reflection is not of an Andreev character, as it was suggested earlier, but rather of a Bragg character. This is due to the fact that the CDW is actually an electronic crystal, and its wave vector is a reciprocal lattice vector of the electronic crystal. The ratio of the intensities of the standard and Bragg reflection depends on the phase of the CDW.Comment: 9 pages, no figures, revte

Electron transport through a mesoscopic metal-CDW-metal junction

In this work we study the transport properties of a finite Peierls-Fr\"ohlich dielectric with a charge density wave of the commensurate type. We show that at low temperatures this problem can be mapped onto a problem of fractional charge transport through a finite-length correlated dielectric, recently studied by Ponomarenko and Nagaosa [Phys. Rev. Lett {\bf 81}, 2304 (1998)]. The temperature dependence of conductance of the charge density wave junction is presented for a wide range of temperatures.Comment: Latex, Revtex 3.0, 7 pages, 2 EPS figures (uses epfs

Non-invasive methods of laser-therapy un complex treatment of the patients with gastroduodenal ulcer

160 patients with stomach ulcer disease (SUD) and 136 patients with duodenal ulcer (DU) at the age of 18-60 years were selected by the method of routine randomization on the basis of the gastroenterological department of the MUS CCH № 3. The course of laserotherapy was added to the treatment of 110 patients with SUD and 86 patients with DU. 56 patients with SUD and 42 with DU underwent overvenous irradiation of blood with red laser in the regional cubital vein with the use of laserotherapeutic apparatus uAsor-2K". In treatment of 54 patients SUD and 44 patients with DU laserotherapeutic apparatus "ADEPT-Euro” with quasofrequency emmitor was used for local transcutaneus irradiation in the region of ulcerative defect. Considerable differences in longevity of the main clinical symptoms were found depending on age and methods of laserotherapy actions.The application of “Asor-2K” in such patients, independently of their age, made in possible to decrease of symptoms terms from vegeto - vascular system, while the use of "ADEPT-Euro” was of more active action on the symptoms of digestive tract.На базе гастроэнтерологического отделения МУЗ ГКБ №3 методом простой рандомизации было отобрано 160 больных ЯБЖ и 136 больных ЯБДПК в возрасте от 18 до 60 лет. Среди обследуемых были выделены 2 возрастные группы — до 50 лет и старше 50-летнего возраста. К лечению 110 больных ЯБЖ и 86 больных ЯБДПК был добавлен курс лазеротерапии. 56 больным ЯБЖ и 42 больным ЯБДПК проводилось надвенное облучение крови красным лазером в области кубитальной вены с использованием лазеротерапевтического аппарата «Азор - 2К». В лечении 54 больных ЯБЖ и 44 больных ЯБДПК был использован лазеротерапевтический аппарат «АДЕПТ-Евро» с квазичастотным излучателем для местного транскутанного облучение области язвенного дефекта. У больных ЯБЖ и ЯБДПК выявлены значительные различия продолжительности основных клинических симптомов в зависимости от возраста больных и способов воздействия лазеротерапии. Применение «Азор-2К» у больных ЯБДПК независимо от возраста, более способствовало сокращению сроков симптоматики со стороны вегето-сосудистой системы, тогда как применение «АДЕПТ-Евро» оказывало более активное воздействие на симптомы со стороны ЖКТ

СПОСОБЫ ПОВЫШЕНИЯ БЕЗОПАСНОСТИ КАТЕТЕРИЗАЦИИ ВНУТРЕННЕЙ ЯРЕМНОЙ ВЕНЫ ПРИ ГИПОВОЛЕМИИ

The aim of research is to study the possibility to increase the security of the internal jugular vein catheterization through the choice of access to puncture it, based on the values of its size.Materials and methods. Ultrasound scanning of IJV with the measurement of anteriorposterior and medial-lateral size was conducted among 20 healthy adult volunteers (control group) and 16 adult patients (observation group) who were treated in the Anesthesiology and Resuscitation Department.Results. It was found that the test values in the control group the anterior-posterior and medial-lateral vein is larger than 7 mm in both inhalation and exhalation. Under the conditions of hypovolemia (observation group) anterior-posterior size IJV inspiratory became less than 7 mm, and the medial-lateral vein size, despite its decrease retained value of more than 7 mm in most subjects. Among healthy volunteers it was found that the rotation of the ultrasonic sensor 45 ° is accompanied by increase in the average values of the medial-lateral vein size by more than 50%. This maneuver may be useful for patients whose value of the medial-lateral vein size inspiratory was less than 7 mm.Conclusion. The choice of central or lateral approach to puncture the internal jugular vein may be based on the actual values of the anterior-posterior and medial-lateral dimensions of it. The usage of lateral access for catheterization of internal jugular vein under ultrasound imaging can be more secure for patients with hypovolemia. The maneuver of ultrasonic sensor for 45° clockwise can be used to increase the size of the medial-lateral rotation. Цель исследования - изучить возможность повышения безопасности катетеризации внутренней яремной вены (ВЯВ) за счет выбора доступа для ее пункции, основанного на значениях ее размеров.Материалы и методы. Ультразвуковое сканирование ВЯВ с измерением их переднезаднего и медиально-латерального размера проведено у 20 здоровых взрослых добровольцев (контрольная группа) и 16 взрослых пациентов (группа наблюдения), находившихся на лечении в отделении анестезиологии-реанимации.Результаты. Установлено, что у исследуемых контрольной группы значения переднезаднего и медиально-латерального размеров вены превышали 7 мм как на вдохе, так и на выдохе. В условиях гиповолемии (группа наблюдения) переднезадний размер ВЯВ на вдохе становился менее 7 мм, а медиально-латеральный размер вены, несмотря на свое уменьшение, у большинства исследуемых сохранял значение более 7 мм. На здоровых добровольцах установлено, что поворот ультразвукового датчика на 45° сопровождается увеличением средних значений медиально-латерального размера вены более чем на 50%. Данный маневр может быть полезен для пациентов, у которых медиально-латеральный размер вены на вдохе оказался менее 7 мм.Заключение. Выбор центрального или латерального доступа для пункции внутренней яремной вены может быть основан на фактических значениях переднезаднего и медиально-латерального ее размеров. У пациентов с гиповолемией использование латерального доступа для катетеризации внутренней яремной вены в условиях ультразвуковой визуализации может быть более безопасным. Для увеличения медиально-латерального размера может быть применен маневр поворота ультразвукового датчика на 45° по часовой стрелке.

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

A new method for the synthesis of peroxomonophosphate, based on the use of boron-doped diamond electrodes, is described. The amount of oxidant electrogenerated depends on the characteristics of the supporting media (pH and solute concentration) and on the operating conditions (temperature and current density). Results show that the pH, between values of 1 and 5, does not influence either the electrosynthesis of peroxomonophosphate or the chemical stability of the oxidant generated. Conversely, low temperatures are required during the electrosynthesis process to minimize the thermal decomposition of peroxomonophosphate and to guarantee significant oxidant concentration. In addition, a marked influence of both the current density and the initial substrate is observed. This observation can be explained in terms of the contribution of hydroxyl radicals in the oxidation mechanisms that occur on diamond surfaces. In the assays carried out below the water oxidation potential, the generation of hydroxyl radicals did not take place. In these cases, peroxomonophosphate generation occurs through a direct electron transfer and, therefore, at these low current densities lower concentrations are obtained. On the other hand, at higher potentials both direct and hydroxyl radical-mediated mechanisms contribute to the oxidant generation and the process is more efficient. In the same way, the contribution of hydroxyl radicals may also help to explain the significant influence of the substrate concentration. Thus, the coexistence of both phosphate and hydroxyl radicals is required to ensure the generation of significant amounts of peroxomonophosphoric acid

Features of electrochemical formation of metal and semiconductor nanowires in anodic alumina matrices with variable pores

Methods for the porous membranes formation from anodic alumina with periodically alternating pore diameters along the membrane depth and the electrochemical nanowires formation of complex morphology from various materials have been developed and tested. The features of the electrochemical deposition of indium and copper antimonide into pores with varying diameters under different chemical conditions and electrical modes have been investigated. The electron microscopic studies of the created nanosystems have been carried out, the elemental composition has been investigated, the current-voltage characteristics of InSb nanowires of complex morphology have been measured

Clinical and epidemiological characteristics of cancers associated with human papillomavirus in the regions of North-West Russia

Introduction. The leading role of the human papillomavirus in the etiopathogenesis of malignant neoplasms of some localizations is generally recognized. Vaccines that are used in the world and in Russia for the prevention of papillomavirus infection create the basis for the elimination of diseases associated with the human papillomavirus in the future. The aim of the study is to determine the regional, gender and age-specific features of cancers associated with the human papillomavirus to substantiate the development of a unified system of epidemiological surveillance and vaccination. Materials and methods. The retrospective epidemiological analysis of the incidence of cancers associated with the human papillomavirus and mortality due to these neoplasms in the regions of the North-Western Federal District of Russia in 20112020 was carried out based on data from Statistic Form 7 "Information on malignant neoplasms" and the Population cancer Registers of St. Petersburg (13,117 cases), Leningrad region (3204 cases) and the Kaliningrad region (2898 cases). Results. In the structure of cancers associated with the human papillomavirus in St. Petersburg, Leningrad and Kaliningrad regions, more than 90% of men had tumors of the oral cavity, oropharynx and larynx, more than 60% of women had cervical cancer. Regional and age-specific features of the incidence of cervical cancer and mortality from this pathology have been established. Statistically significant differences in the incidence of cancer of the head and neck, anus and anal canal in different age groups of the male and female population were revealed. Conclusion. As a result of the study, regional, gender and age-specific features of the incidence of human papillomavirus-associated malignant neoplasms in the North-West of Russia were established. These data should be used to develop a system of epidemiological surveillance of papillomavirus infection and vaccination program