Field-asymmetric transverse magnetoresistance in a nonmagnetic quantum-size structure

A new phenomenon is observed experimentally in a heavily doped asymmetric quantum-size structure in a magnetic field parallel to the quantum-well layers - a transverse magnetoresistance which is asymmetric in the field (there can even be a change in sign) and is observed in the case that the structure has a built-in lateral electric field. A model of the effect is proposed. The observed asymmetry of the magnetoresistance is attributed to an additional current contribution that arises under nonequilibrium conditions and that is linear in the gradient of the electrochemical potential and proportional to the parameter characterizing the asymmetry of the spectrum with respect to the quasimomentum.Comment: 10 pages, 5 figures. For correspondence, mail to [email protected]

Wave-vector dependent intensity variations of the Kondo peak in photoemission from CePd3_3

Strong angle-dependent intensity variations of the Fermi-level feature are observed in 4d - 4f resonant photoemission spectra of CePd$_3$(111), that reveal the periodicity of the lattice and largest intensity close to the Gamma points of the surface Brillouin zone. In the framework of a simplified periodic Anderson model the phenomena may quantitatively be described by a wave-vector dependence of the electron hopping matrix elements caused by Fermi-level crossings of non-4f-derived energy bands

Dispersion of a single 4f4f impurity state in photoemission spectra of Yb/W(110)

Angle-resolved photoemission spectra of a monolayer of Yb on W(110) reveal energy splittings and dispersion of the Yb 4f states that are obviously due to their hybridization with W-derived valence bands. These effects occur at well defined points of the surface Brillouin zone although a smearing over reciprocal space is expected from the structural incoherence of the Yb and W lattices. We conclude therefore that dispersion is not related to the periodic arrangement of the $4f$ states but reflects the k-dependent interaction of a single Yb 4f impurity with W bands.Comment: 7 pages, 4 figure

CeFePO: f-d hybridization and quenching of superconductivity

Being homologue to the new, Fe-based type of high-temperature superconductors, CeFePO exhibits magnetism, Kondo and heavy-fermion phenomena. We experimentally studied the electronic structure of CeFePO by means of angle-resolved photoemission spectroscopy. In particular, contributions of the Ce 4f-derived states and their hybridization to the Fe 3d bands were explored using both symmetry selection rules for excitation and their photoionization cross-section variations as a function of photon energy. It was experimentally found - and later on confirmed by LDA as well as DMFT calculations - that the Ce 4f states hybridize to the Fe 3d states of d_{3z^2-r^2} symmetry near the Fermi level that discloses their participation in the occurring electron-correlation phenomena and provides insight into mechanism of superconductivity in oxopnictides.Comment: 5 pages, 3 figure

ГІПОКСИЧНО-ІШЕМІЧНЕ УШКОДЖЕННЯ ГОЛОВНОГО МОЗКУ ПЛОДА: ПРОГНОЗУВАННЯ ТА ПОПЕРЕДЖЕННЯ

The aim of the study – to investigate the influence of risk factors in the mother and morbidity in the neonatal period on the development of hypoxic-ischemic encephalopathy of newborns, depending on their gestational age, as well as to determine the effect of neuroprotection on the development of hypoxic brain lesions in premature infants. Materials and Methods. At the first stage, a retrospective analysis of the course of pregnancy, childbirth and the condition of newborns was carried out in 150 women whose children had suffered from hypoxic-ischemic brain damage. Group I (GI) consisted of 62 women who gave birth to full-term babies, Group II (GII) – 88 women who gave birth prematurely at 26+6–33+6 weeks of gestation. At the second stage, the level of neurospecific markers of nerve tissue damage (NSE and S100) was prospectively investigated in 60 preterm infants at gestational terms up to 32 weeks, who were divided into two groups. The main group (MG) consisted of 30 preterm infants whose mothers were injected with magnesium sulfate for the purpose of neuroprotection, the comparison group (CG) – 30 preterm infants whose mothers did not receive neuroprotection for various reasons. Results and Discussion. The risk factors for the birth of children with HIE include extragenital pathology in the mother (OR 1090.818, 95 % CI 64.501–18447.401), urogenital infections – chlamydia (OR 21.87, 95 % CI 1.264 – 378.397), prematurity, low weight bodies at birth, PROM, chorionamnionitis (OR 17.6, 95 % CI 2.288 – 135.407), Apgar score <7 points, morbidity in the neonatal period. Neurospecific enolase (NSE) was significantly higher in children with gestational age up to 32 weeks and an Apgar score of <6 points. The lower concentration of protein S100 in newborns of the main group can be explained by the protective effect of magnesium sulfate on the central nervous system of a premature newborn. Conclusions. Risk factors for neurological disorders in newborns include extragenital pathology, urogenital infections of the mother, prematurity, premature rupture of the membranes, the development of chorionamnionitis, and fetal growth retardation. Conducting neuroprotection with magnesium sulfate before delivery is an important measure to prevent hypoxic-ischemic brain damage to the fetus and premature newborn.Цель исследования – изучить влияние факторов риска у матери и заболеваемости в неонатальном периоде на развитие гипоксически-ишемической энцефалопатии (ГИЭ) новорожденных в зависимости от их гестационного возраста, а также определить влияние нейропротекции на развитие гипоксических поражений головного мозга у недоношенных новорожденных. Материалы и методы. На первом этапе проведен ретроспективный анализ течения беременности, родов и состояния новорожденных у 150 женщин, дети которых перенесли гипоксически-ишемическое поражение головного мозга. І группу (І Г) составили 62 женщины, родившие доношенных детей, II группу (ІІ Г) – 88 женщин, родивших преждевременно в сроке 26+6–33+6 недель гестации. На втором этапе проспективно исследован уровень нейроспецифических маркеров повреждения нервной ткани (NSE и S100) у 60 недоношенных новорожденных в сроках гестации до 32 недель, которые были разделены на две группы. Основную группу (ОГ) составили 30 недоношенных новорожденных, матерям которых вводился сульфат магния с целью нейропротекции, группу сравнения (СГ) – 30 недоношенных новорожденных, матери которых по разным причинам нейропротекцию не получили. Результаты исследования и их обсуждение. К факторам риска рождения детей с ГИЭ относятся экстрагенитальная патология у матери (ОШ 1090,818, 95 % ДИ 64,501–18 447,401), урогенитальные инфекции – хламидиоз (ОШ 21,87, 95 % ДИ 1,264–378,397), недоношенность, низкая масса тела при рождении, ПРПО, хорионамнионит (ОШ 17,6, 95 % ДИ 2,288–135,407), оценка по шкале Апгар <7 баллов, заболеваемость в неонатальном периоде. Нейроспецифическая энолаза (NSE) была достоверно выше у детей со сроком гестации до 32 недель и оценкой по Апгар <6 баллов. Более низкая концентрация белка S100 у новорожденных основной группы может объясняться защитным действием сульфата магния на ЦНС недоношенного новорожденного. Выводы. К факторам риска неврологических нарушений у новорожденных относятся экстрагенитальная патология, урогенитальные инфекции у матери, недоношенность, преждевременный разрыв плодных оболочек, развитие хорионамнионита, задержка роста плода. Проведение нейропротекции сульфатом магния перед родоразрешением является важной мерой предупреждения гипоксически-ишемического повреждения головного мозга плода и недоношенного новорожденного.Мета дослідження – вивчити вплив факторів ризику в матері та захворюваності у неонатальному періоді на розвиток гіпоксично-ішемічної енцефалопатії (ГІЕ) новонароджених залежно від їх гестаційного віку, а також дослідити вплив нейропротекції на розвиток гіпоксичних уражень головного мозку в недоношених новонароджених. Матеріали та методи. На першому етапі проведено ретроспективний аналіз перебігу вагітності, пологів та стану новонароджених у 150 жінок, діти яких перенесли гіпоксично-ішемічне ураження головного мозку. І групу (ІГ) склали 62 жінки, які народили доношених дітей, ІІ групу (ІІГ) – 88 жінок, які народили передчасно у терміні 26+6–33+6 тижнів гестації. На другому етапі проспективно досліджено рівень нейроспецифічних маркерів пошкодження нервової тканини (NSE та S100) у 60 недоношених новонароджених у термінах гестації до 32 тижнів, які були розподілені на дві групи. Основну групу (ОГ) склали 30 недоношених новонароджених, матерям яких вводили сульфат магнію з метою нейропротекції, групу порівняння (ПГ) – 30 недоношених новонароджених, матері яких із різних причин нейропротекцію не отримали. Результати дослідження та їх обговорення. До факторів ризику народження дітей із ГІЕ належать екстрагенітальна патологія у матері (ВШ 1090,818, 95 % ДІ 64,501–18 447,401), урогенітальні інфекції – хламідіоз (ВШ 21,87, 95 % ДІ 1,264–378,397), недоношеність, низька маса тіла при народженні, ПРПО, хоріонамніоніт (ВШ 17,6, 95 % ДІ 2,288–135,407), оцінка за шкалою Апгар <7 балів, захворюваність у неонатальному періоді. Нейроспецифічна енолаза (NSE) була вірогідно вища у дітей із терміном гестації до 32 тижнів та оцінкою за Апгар менше 6 балів. Нижча концентрація білка S100 у новонароджених основної групи може пояснюватись захисною дією сульфату магнію на ЦНС недоношеного новонародженого. Висновки. До факторів ризику неврологічних порушень у новонароджених належать екстрагенітальна патологія, урогенітальні інфекції у матері, недоношеність, передчасний розрив плодових оболонок, розвиток хоріонамніоніту, затримка росту плода. Проведення нейропротекції сульфатом магнію перед розродженням є важливим заходом попередження гіпоксично-ішемічного ушкодження головного мозку плода та недоношеного новонародженого

Regarding the standardization of L-arginine and thiotriazoline in the model mixture by high-performance liquid chromatography

Today, one of the main causes of disability and mortality in the world's population is the disease of the cardiovascular and central nervous systems. Therefore, the development of new highly effective drugs for their treatment becomes an urgent task of modern medicine and pharmacy. Promising in this direction is the creation of a new medicinal product, which combines the active donor NO – neurotransmitter amino acid L-arginine, as well as the famous domestic antioxidant – thiotriazoline. A rational dosage form – pills was chosen to create a new combined drug. Therefore, the actual and timely task is to develop methods for standardizing the active substances in the model mixture, which in future can become the basis for the analysis of the finished dosage forms of the new drug. The purpose of the work is to develop a method for standardizing the model mixture of L-arginine and thiotriazoline in the ratio of 4:1 by HPLC method. Materials and methods. During the research, certified substances L-arginine (manufacturer: Sigma-Aldrich, USA) and thiotriazolin (manufacturer State Enterprise “Chemical Reagents Plant” of the Scientific-Technological Complex “Institute of Single Crystals” of the National Academy of Sciences of Ukraine) were used. The research was carried out using LC-20 Prominence Shimadzu Chromatograph. Results. First, in the laboratory, six series of model mixture of L-arginine and thiotriazoline were produced in an optimum ratio of 4:1. Continuously, the test solution and the solution of the working standard sample, were chromatographed obtaining at least three chromatograms for each solution. It is established that the content of L-arginine in the model mixture ranges from 198.38 mg to 200.66 mg, and thiotriazoline is from 50.82 mg to 51.61 mg. According to the content of the active substances, the studied series of model mixture of L-arginine and thiotriazoline in a ratio of 4:1 correspond to the requirements of the SPF. Conclusions. In the course of the conducted researches the method of standardization of active substances of the model mixture of L-arginine and thiotriazoline in a ratio of 4:1 by the HPLC method, which is reproducible, accurate and can be used later in the quality control of the established tablet formulation, has been developed

Retrospective analysis and materials of authors' researches of stomatological morbidity at the hyperfluorosis

The authors conducted retrospective analysis and study of materials of their own clinical researches of stomatological morbidity both of population of the ecologically adverse region and. workers of manufactures connected with fluorine outburst into environment. Analysis of stomatological morbidity was performed in two variations: 1) retrospective analysis of out-patient charts over 2000—2008; 2) analysis of own clinical observations over 2007—2010. 1245 out-patient charts of two groups (the first one — residents of Irkutsk, the second. — residents of Angarsk) were retrospectively analyzed. Depending on nosological form and. degree of manifestation of stomatological pathology all obtained material was divided in three main parts: teeth affection (I), pathology of tunica mucosa of mouth. (II) and. lesions of periodontium. (III). In population of the ecologically affected region (the second and. third groups) lesions of parodontium, were found to increase in numbers depending on duration of residence or length of work. At the same time in this category of patients we marked the increase of more generalized forms (generalized periodontitis, periodontosis) of affections. In the third group on the background of lessening of periodontitis and nidal periodontosis diagnostics there is growth of destructive-dystrophic changes in periodontium, the intensity of which is directly proportional to increasing of time of exposition of pathogenic factor. And, as a consequence, the number of more generalized forms of stomatological pathologies increases, which correspondingly demands working out and. introducing into practice up-to-date systems of treatment-diagnostic and. preventive measurements for this category of population

Clinical-radiological aspects of development of dental fluorosis

There have been a clinical-roentgenological research of influence of chronicle fluorine intoxication on the change of periodontium structures which in conditions of hyperfluorosis have systemic character and predetermine certain clinical-roentgenological manifestations and development of pathological processes in periodontum. The research has been performed basing on clinical-roentgenological manifestations of fluorosis observed both in population of ecologically adverse regions and. in workers of plants and with the help of comparative analysis of the results received during the study. Analysis of the obtained data of clinical-roentgenological changes of periodontum. at chronic fluorine intoxication showed that in the first (control) group observed manifestations stayed within the limits of age changes in this region. In the second group pathological signs were marked during the second time period. (6—10 years), henceforth clinical picture of affected periodontium structures became aggravated. In workers of chemical production because of more intense accumulation of fluoric compounds in structures of periodontium clinical signs of it affection are displayed in the first and. avalanche-like grow in the second and the third time periods, whereas destructive-dystrophic changes in periodontium have more generalized and. irreversible character. The dynamics of revealed clinical-roentgenological manifestations happening in structures of periodontium shows that with the increase of time of residence on the territory and length of service on the manufacture, destructive-dystrophic processes in those structures become more extended

Optimization of L-tryptophan and thiotriazoline compound analysis by high-performance liquid chromatography

Introduction. An actual task of modern medicine is the development of treatment methods of the central nervous system diseases. The solution of this problem was the creation of new, more effective neuropsychotropic drug that shows pronounced antidepressant, nootropic, neuroprotective and antioxidant effects based on the fixed combination of L-tryptophan with thiotriazoline. One of the steps in creating a new drug is the standardization of active ingredients. Today, much attention is being paid to new physical-chemical methods of drugs study, including high-performance liquid chromatography (HPLC). Increasingly, the HPLC method is used for the determination of active ingredients of organic nature, both in mono-preparations and in combined dosage forms. Therefore, we have proposed the HPLC method for new combined L-tryptophan and thiotriazoline drug in order to determine active substances based on their effects. The purpose of our study is to develop a method for the simultaneous standardization of L-tryptophan and thiotriazoline in an artificial compound by high-performance liquid chromatography, in particular the selection of the mobile and stationary phase. Materials and methods. In the first stage of our work, a selection of phase and eluents was carried out for L-tryptophan and thiotriazoline model compound in a ratio of 1:1. The analysis method of thiotriazoline in the reverse phase (C 18) using the eluents, which are water-methanol compounds, was taken as a basis. Results. In the course of study, it was found that the retention volume of both tryptophan and thiotriazoline decreased, and the peak distribution coefficient increased with the number of theoretical plates with increasing content of methanol in phosphate buffer compound. Therefore, as an eluent, attention was drawn to a solution of 20% methanol with 80 % phosphate buffer. Under these conditions, the tryptophan retention volume was 15.11 ml, thiotriazoline – about 6.05 ml, the efficacy of the chromatographic column, calculated on the tryptophan peak of about 3300 theoretical plates. Findings: A highly sensitive technic was developed as part of the study for the simultaneous determination of L-tryptophan and thiotriazoline in a model mixture by HPLC (high performance liquid chromatography method, that is planned to be used in further study, was developed as a part of the study. The method is developed not only for L-tryptophan and thiotriazoline standardization in the combined drug, but also for their determination in biological fluids