Capture of carriers to screened charged centres and low temperature shallow impurity electric field break down in semiconductors

Free carrier capture by a screened Coulomb potential in semiconductors are considered. It is established that with decreasing screening radius the capture cross section decreases drastically, and it goes to zero when $$. On the basis of this result a new mechanism of shallow impurity electric field break down in semiconductors is suggested.Comment: 8 pages, latex, 1 figure in gif format, to be submitted to "Journal of Condensed Matter

Unoccupied Topological States on Bismuth Chalcogenides

The unoccupied part of the band structure of topological insulators Bi$_2$Te$_{x}$Se$_{3-x}$ ($x=0,2,3$) is studied by angle-resolved two-photon photoemission and density functional theory. For all surfaces linearly-dispersing surface states are found at the center of the surface Brillouin zone at energies around 1.3 eV above the Fermi level. Theoretical analysis shows that this feature appears in a spin-orbit-interaction induced and inverted local energy gap. This inversion is insensitive to variation of electronic and structural parameters in Bi$_2$Se$_3$ and Bi$_2$Te$_2$Se. In Bi$_2$Te$_3$ small structural variations can change the character of the local energy gap depending on which an unoccupied Dirac state does or does not exist. Circular dichroism measurements confirm the expected spin texture. From these findings we assign the observed state to an unoccupied topological surface state

Revision Anterior Cruciate Ligament Reconstruction: Current Approaches to Preoperative Planning (Systematic Review)

Background. The number of primary anterior cruciate ligament (ACL) reconstructions increases every year, which causes an increase in revision interventions due to ACL graft failure. When studying the literature, we identify many factors that together influence the outcome of revision ACL reconstruction, but are not always taken into account by surgeons. Aim of the review — is to perform a systematic review of studies that evaluated the outcomes of revision anterior cruciate ligament reconstructions and to identify optimal solutions to the most common problems encountered in preoperative planning. Methods. Information search was performed in the eLIBRARY, PubMed, and Scopus databases for the period from 2013 to 2022. Studies describing the main aspects of revision ACL reconstruction were selected for analysis. Inclusion criteria were the following: mean patient follow-up period of no less than 12 months, number of observations of no less than 10 cases. After evaluation of 898 articles, 22 articles were included in the systematic review. Results. Five main factors that should be taken into account in preoperative planning of revision ACL reconstruction have been identified: choice of the graft, necessity of reconstruction of the anterolateral complex, correction of tibial plateau deformity in the sagittal plane, determination of indications for one- or two-stage intervention, method of bone defect replacement in two-stage surgical treatment. Conclusion. The patient’s autogenous tissues should be preferred when choosing a graft. Correction of excessive anteroposterior tibial plateau inclination angle is performed only at the second revision intervention if the inclination angle exceeds 12º. Reconstruction of the anterolateral complex should be performed in young, active patients who are involved in pivot sports and in case of severe anterior instability. When determining the possibility of performing revision ACL reconstruction in one or two stages, the canal diameter is not a crucial parameter, as it is necessary to take into account the possibility of fusion of the canals from the previous surgery with the newly created ones. If the canals have correct entry points, one-stage revision reconstruction can be performed with the canal width not exceeding 10 mm and depending on the expected diameter and type of the prepared tendon graft. Bone grafting of the secondary dilated canals in two-stage intervention can be carried out using any material, but allogenous bone or synthetic grafts have certain advantages

The influence of climatic factors on the course of pregnancy in women of the far north

The article describes the influence of climatic and geographic conditions on the course of pregnancy in women of the Tazovsky district in the far North (Yamalo-Nenets). After analyzing the course of pregnancy on individual cards found that the course of pregnancy has a significant effect on the change in photoperiodicity. In the years of high solar activity, the frequency of complications increases in indigenous and alien residents. In this regard, it is necessary to carry out preventive measures to identify and eliminate complications during pregnancy in all residents of the NorthВ статье рассмотрено влияние климато-географических условий на течение беременности у жительниц Тазовского района Крайнего Севера (ЯНАО). Проанализировав течение беременности по индивидуальным картам установлено, что на течение беременности существенное влияние оказывает изменение фотопериодичности. В годы высокой солнечной активности частота осложнений возрастает у коренных и пришлых жительниц. В связи с этим необходимо проведение профилактических мероприятий по выявлению и устранению осложнений на течение беременности у всех жительниц Север

The influence of climatic factors on the course of pregnancy in women of the far north

The article describes the influence of climatic and geographic conditions on the course of pregnancy in women of the Tazovsky district in the far North (Yamalo-Nenets). After analyzing the course of pregnancy on individual cards found that the course of pregnancy has a significant effect on the change in photoperiodicity. In the years of high solar activity, the frequency of complications increases in indigenous and alien residents. In this regard, it is necessary to carry out preventive measures to identify and eliminate complications during pregnancy in all residents of the NorthВ статье рассмотрено влияние климато-географических условий на течение беременности у жительниц Тазовского района Крайнего Севера (ЯНАО). Проанализировав течение беременности по индивидуальным картам установлено, что на течение беременности существенное влияние оказывает изменение фотопериодичности. В годы высокой солнечной активности частота осложнений возрастает у коренных и пришлых жительниц. В связи с этим необходимо проведение профилактических мероприятий по выявлению и устранению осложнений на течение беременности у всех жительниц Север

STUDY OF THE EFFICIENCY AND SAFETY OF MYCOPHENOLATE MOFETIL THERAPY IN PATIENTSWITH SYSTEMIC SCLERODERMA

Interstitial lung disease (ILD) is one of the major causes of death in systemic scleroderma (SSD). Treatment of these patients remains difficult and controversial. Mycophenolate mofetil (MPM) has been in vitro shown to inhibit overproduction of type I collagen and hence may be effective against SSD. Objective: to study the efficiency and safety of MPM therapy in patients with SSD and clinically relevant ILD in an open-label prospective study. Subjects and methods. Ten patients with SSD (7 and 3 with its diffuse and limited forms, respectively) and ILD were given MPM in combination with glucocorticoids (mean daily dose was 10+4 mg). The mean MPM therapy duration was 11.4+1.3 months. The Rodnan total skin thickness score, flexion index, forced vital capacity (FVC), diffusing capacity of the lung for carbon monoxide (DLCO), and European Scleroderma Study Group (EScSG) activity index were estimated and a 6-minute walk test (6MWT) was carried out before and after MPM therapy. Results. After therapy, the whole group showed a significant reduction in skin scores from 12.9+9.8 to 5.6+3.2 (p=0.036) and EScSG from 3.9+1.4 to 2.25+1.03 (p=0.015) and an increase in exercise tolerance from 446+155 to 535+78 m (p=0.03) as evidenced by 6MWT. The degree of flexion contractures decreased from 15+21 to 3.7+11.3 mm (p>0.05). FVC (77.8+18.7% versus 73.8+11.3%) and DLCO (45+14.4% versus 42+16.4%) were significantly unchanged. A 10% or more clinically significant fall was noted in FVC and DLCO in 3 and 1 patients, respectively. In the remaining patients, the lung functional test results remained stable. MPM tolerability was satisfactory. All the patients completed their course of treatment. Conclusion. Stabilization of lung function with higher exercise tolerance and significantly reduced skin density allow therapy with MPM in combination with low-dose glucocorticoids to be regarded as an effective and well-tolerated treatment in patients with ILD in the presence of SS

Состояние минеральной плотности кости у пациентов с системной склеродермией

Objective: to assess the frequency of a reduction in bone mineral density (BMD) and its association with traditional risk factors and clinical parameters in patients with systemic scleroderma (SSD).Patients and methods. The investigation included 330people: 190 patients (median age 55 [41; 61.5] years) with SSD and 140 control individuals (median age 57 [40.5; 66] years without a history of inflammatory rheumatic diseases. The patients were interviewed using a uniform questionnaire; dual-energy X-ray absorptiometry was used to measure BMD in the lumbar spine (Li-iv), femoral neck (FN), entire proximal femur (PF), and distal third of the forearm (DTF). The concentration of 25(OH)D was measured in 155 examinees.Results and discussion. Decreased BMD was found in 69% of patients with SSD and in 58% of controls (p=0.0392), including osteoporosis (OP) in 38 and 31% of cases, respectively. BMD in the Li-iv and FN was significantly lower in the women with SSD than in the control exam-nees, regardless of age. There was a direct correlation between BMD and body mass index (BMi) and an inverse correlation between BMD and the duration of menopause, that of the disease, and cumulative dose of glucocorticoids (GCs). Among the analyzed clinical factors, there was an inverse correlation between Li-iv BMD and erythrocyte sedimentation rate (ESR), between BMD in both femoral areas (FN and PF) and C-reactive protein (CRP). The mean concentration of 25(OH)D was 19.83+11.06 ng/mL in the patients with SSD and 23.29+8.61 ng/mL in the controls; normal vitamin D levels were detected in 9% of the patients with SSD and 24% of the controls (p<0.05).Conclusion. Low BMD was found in 69% of patients with SSD, including in those with OP (38%). Most (91%) patients had vitamin D deficiency. BMD correlated with traditional risk factors: positively with BMi and negatively with age and menopause duration. The clinical factors were found to be association with disease duration and cumulative GC dose.Цель исследования — оценка частоты снижения минеральной плотности кости (МПК) и ее взаимосвязи с традиционными факторами риска и клиническими параметрами у пациентов с системной склеродермией (ССД).Пациенты и методы. В исследование включено 330 человек: 190 пациентов с ССД (медиана возраста 55 [41; 61,5] лет) и 140 лиц контрольной группы без воспалительных ревматических заболеваний в анамнезе (медиана возраста 57[40,5; 66] лет). Пациенты были опрошены с помощью унифицированной анкеты, МПК измеряли с использованием двуэнергетической рентгеновской абсорб-циометрии в поясничном отделе позвоночника (Li-rv), шейке бедра (ШБ), проксимальном отделе бедра в целом (ПОБ) и в области трети дистального отдела предплечья (ДОП). Определение концентрации 25(OH)D проведено у 155 обследованных.Результаты и обсуждение. Сниженная МПК выявлена у 69% пациентов с ССД и 58% лиц контрольной группы (р=0,0392), в том числе остеопороз (ОП) — у 38 и 31% соответственно. Величина МПК у женщин с ССД в Li-ivu ШБ была значимо меньше, чем у обследованных контрольной группы, независимо от возраста. Установлена прямая корреляция между величиной МПК и индексом массы тела (ИМТ) и обратная — с продолжительностью постменопаузы, длительностью заболевания, кумулятивной дозой глюкокортикоидов (ГК). Среди проанализированных клинических факторов обнаружена обратная зависимость между МПК в Li-vu СОЭ; между МПК в обеих областях ПОБ (ШБ и ПОБ) и СРБ. Средняя концентрация 25(OH)D составила 19,83+11,06нг/мл у пациентов с ССД и 23,29+8,61 нг/мл у лиц контрольной группы; нормальный уровень витамина D определен у 9 и 24% обследованных соответственно (p<0,05).Выводы. Низкая МПК выявлена у 69% пациентов с ССД, в том числе ОП - у 38%. Недостаточность и дефицит витамина D имелись у 91% больных. Величина МПК коррелировала с традиционными факторами риска: позитивно с ИМТ и негативно с возрастом и продолжительностью постменопаузы. Среди клинических факторов установлена связь с длительностью заболевания и кумулятивной дозой ГК

Изолированное снижение диффузионной способности легких при системной склеродермии без легочной артериальной гипертензии: длительное проспективное наблюдение

The objective of this 5year prospective study was to investigate a clinical role of isolated decrease of DLCO in patients with systemic sclerosis (SS) without pulmonary arterial hypertension (PAH).Methods. We selected 48 out of 142 patients with SS: 35 (73%) with limited SS and 13 (27%) with diffuse SS. The average length of the disease was 12.9 ± 7.9 years. Inclusion criteria were DLCO < 80% pred., forced vital capacity (FVC) ≥ 80% pred. and systolic pulmonary artery pressure (PAP) ≤ 35 mm Hg according to echocardiographic examination (echoCG). High resolution computed tomography (HRCT), spirometry, DLCO measurement, and echoCG were obtained at baseline and after 4.7 ± 1 year of follow up. All patients were treated with standard therapy.Results. CT signs of interstitial lung disease (ILD) were found in 43 (89.6%) patients at baseline and newly developed in 3 other patients during the followup. During the followup, lung CT improved in 5 (10.4%) patients and progressed in 15 (31.3%) patients. Over 5 years, FVC did not change significantly (97.6 ± 10.7% and 100.8 ± 18.9%; р = 0.15), while DLCO significantly decreased both in limited and diffuse SS groups (59.8 ± 13.5% and 56.3 ± 12%; р = 0.006). Mean PAP values remained within normal range in majority of patients. Clinically significant FVC reduction (≥ 10%) was found in 5 patients; of them, CT signs of ILD at baseline were seen in 3 patients and newly developed during the followup in 2 others. Clinically significant DLCO reduction (≥ 10%) was documented in 11 (23%) patients, all had CT signs of ILD at baseline, although CT progression during the followup was noted only in six of them. Contemporary deterioration in FVC, DLCO and CT was found in 3 patients.Conclusion. Clinical course of ILD in SS patients with isolated DLCO reduction and without PAH was relatively benign, with respiratory volumes being preserved within normal range for long time. Comparison of radiological and functional changes in a prospective study has suggested that DLCO is a more sensitive tool to determine ILD progression compared to HRCT. Regular DLCO measurements could be used as a reliable tool for monitoring of ILD associated with SS.Интерстициальное поражение легких (ИПЛ) при системной склеродермии (ССД), как правило, сопровождается рестриктивными нарушениями легочной функции, при этом снижение дыхательных объемов и диффузионной способности легких (DLCO) происходит параллельно. В ряде случаев при ИПЛ выявляется изолированное снижение DLCO, клиническое значение которого остается до конца неясным.Цель. Клиническая оценка изолированного снижения DLCO у больных ССД без легочной артериальной гипертензии (ЛАГ) в 5летнем проспективном исследовании.Материалы и методы. Из больных (n = 142), наблюдавшихся в Федеральном государственном бюджетном научном учреждении «Научноисследовательский институт ревматологии имени В.А.Насоновой», отобраны пациенты (n = 48) с лимитированной – 35 (73 %) и диффузной – 13 (27 %) формами ССД (давность ССД – 12,9 ± 7,9 года; снижение DLCO < 80 %; форсированная жизненная емкость легких (ФЖЕЛ) ≥ 80 %долж., отсутствие ЛАГ по данным эхокардиографии (ЭхоКГ); систолическое давление в легочной артерии (СДЛА) ≤ 35 мм рт. ст.). Компьютерная томография высокого разрешения (КТВР), спирометрия, определение DLCO, ЭхоКГ проводились при включении в исследование и через 4,7 ± 1,0 года. Все пациенты получали стандартную терапию.Результаты. При включении в исследование КТпризнаки ИПЛ обнаружены у 43 (89,6 %) больных и через 5 лет появились еще у 3; при этом положительная КТдинамика отмечена у 5 (10,4 %), прогрессирование – у 15 (31,3 %) пациентов. Показатели ФЖЕЛ в среднем по группе значимо не изменились (97,6 ± 10,7 и 100,8 ± 18,9 соответственно; р = 0,15), DLCO достоверно снизилась (59,8 ± 13,5 и 56,3 ± 12,0 % соответственно; р = 0,006). Показатели СДЛА оставались в пределах нормальных значений у большинства пациентов. Клинически значимое (≥ 10 %) снижение ФЖЕЛ выявлено у 5 пациентов, из них в 3 случаях КТпризнаки ИПЛ отмечены при включении в исследование, в 2 – появились в динамике. Клинически значимое снижение DLCO (≥ 10 %) обнаружено у 11 (23 %) пациентов. У всех при 1м обследовании выявлены КТпризнаки ИПЛ, однако только в 6 случаях в динамике отмечалось нарастание рентгенологических признаков ИПЛ. Параллельное снижение ФЖЕЛ и DLCO, сопровождавшееся прогрессированием рентгенологических признаков ИПЛ, выявлено у 3 больных.Заключение. Течение ИПЛ у больных ССД с изолированным снижением DLCO без ЛАГ было относительно доброкачественным с сохранением легочных объемов в пределах нормальных значений в течение длительного времени. При сопоставлении рентгенологической динамики и легочных тестов в проспективном наблюдении отмечено, что в отражении прогрессирования ИПЛ DLCO является более чувствительным тестом, чем КТВР. Регулярное определение DLCO может быть информативным инструментом динамического наблюдения больных ССД при ИПЛ

Electronic properties and phase transitions in low-dimensional semiconductors

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, non-linear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. Electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.Comment: 70 pages, 38 figure