Geometrical Frustration: A Study of 4d Hard Spheres

The smallest maximum kissing-number Voronoi polyhedron of 3d spheres is the icosahedron and the tetrahedron is the smallest volume that can show up in Delaunay tessalation. No periodic lattice is consistent with either and hence these dense packings are geometrically frustrated. Because icosahedra can be assembled from almost perfect tetrahedra, the terms "icosahedral" and "polytetrahedral" packing are often used interchangeably, which leaves the true origin of geometric frustration unclear. Here we report a computational study of freezing of 4d hard spheres, where the densest Voronoi cluster is compatible with the symmetry of the densest crystal, while polytetrahedral order is not. We observe that, under otherwise comparable conditions, crystal nucleation in 4d is less facile than in 3d. This suggest that it is the geometrical frustration of polytetrahedral structures that inhibits crystallization.Comment: 4 pages, 3 figures; revised interpretatio

Study of "racemic compound-like" behavior of diastereomeric mixture of pinanyl sulfoxides by x-ray diffraction, ir spectroscopy, and DFT calculations

The oxidation of a β-hydroxysulfide in the pinane series by use of mchloroperbenzoic acid resulted in the formation of the corresponding β-hydroxysulfoxide as a mixture of two diastereomers in 4:5 ratio. According to single-crystal X-ray diffraction (XRD) results, it is established that the diastereomeric mixture of sulfoxides crystallizes in the "racemic compound-like" manner under formation of asymmetric dimers through S=O··H-O interactions. This asymmetric dimer formed from diastereomeric molecules is a structural unit in both crystal modifications, the triclinic and the monoclinic one. The behavior of the diastereomeric mixture of pinane derived sulfoxides in crystals, melts and in tetrachloromethane solutions was studied by IR spectroscopy. The density functional theory (DFT) method with 6-31G (d, p) basis set was used to calculate the optimized geometrical parameters and vibrational frequencies of different associates in solution. The calculated vibrational frequencies are compared with experimental IR spectra. Copyright © 2014 Taylor & Francis Group, LLC

Применение методов фрактальной и вычислительной геометрии для картографической генерализации линейных объектов

We present an algorithm for simplifying linear cartographic objects and results obtained with a computer program implementing this algorithm.Предлагается новый алгоритм генерализации линейных картографических объектов. Основным новшеством алгоритма является автоматическая сегментация – разбиение ломаной на участки с одинаковыми свойствами. Сегментация позволяет подобрать параметры сглаживания индивидуально для каждого участка, за счет чего существенно повышается качество результата

Bis-phosphonium salts of pyridoxine: The relationship between structure and antibacterial activity

A series of 23 novel bis-phosphonium salts based on pyridoxine were synthesized and their antibacterial activities were evaluated in vitro. All compounds were inactive against gram-negative bacteria and exhibited the structure-dependent activity against gram-positive bacteria. The antibacterial activity enhanced with the increase in chain length at acetal carbon atom in the order n-Pr > Et > Me. Further increasing of length and branching of alkyl chain leads to the reduction of antibacterial activity. Replacement of the phenyl substituents at the phosphorus atoms in 5,6- bis(triphenylphosphonio(methyl))-2,2,8-trimethyl-4H-[1,3]-dioxino[4,5-c] pyridine dichloride (compound 1) with n-butyl, m-tolyl or p-tolyl as well as chloride anions in the compound 1 with bromides (compound 14a) increased the activity against Staphylococcus aureus and Staphylococcus epidermidis up to 5 times (MICs = 1-1.25 μg/ml). But in practically all cases chemical modifications of compound 1 led to the increase of its toxicity for HEK-293 cells. The only exception is compound 5,6-bis[tributylphosphonio(methyl)]-2,2,8- trimethyl-4H-[1,3]dioxino[4,5-c]pyridine dichloride (10a) which demonstrated lower MIC values against S. aureus and S. epidermidis (1 μg/ml) and lower cytotoxicity on HEK-293 cells (CC50 = 200 μg/ml). Compound 10a had no significant mutagenic and genotoxic effects and was selected for further evaluation. It should be noted that all bis-phosphonium salt based on pyridoxine were much more toxic than vancomycin. © 2013 Elsevier Ltd. All rights reserved

Unintentional high density p-type modulation doping of a GaAs/AlAs core-multi-shell nanowire

Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of considerable technological importance but remains a challenge due to the amphoteric behavior of the dopant atoms. Here we show that placing a narrow GaAs quantum well in the AlAs shell effectively getters residual carbon acceptors leading to an \emph{unintentional} p-type doping. Magneto-optical studies of such a GaAs/AlAs core multi-shell NW reveal quantum confined emission. Theoretical calculations of NW electronic structure confirm quantum confinement of carriers at the core/shell interface due to the presence of ionized carbon acceptors in the 1~nm GaAs layer in the shell. Micro-photoluminescence in high magnetic field shows a clear signature of avoided crossings of the $n=0$ Landau level emission line with the $n=2$ Landau level TO phonon replica. The coupling is caused by the resonant hole-phonon interaction, which points to a large 2D hole density in the structure.Comment: just published in Nano Letters (http://pubs.acs.org/doi/full/10.1021/nl500818k

Почечно-клеточный рак с метастазами в наружных половых органах. Обзор литературы и клинический случай

Annually, up to 300 thousand new cases of kidney cancer and more than 134 thousand deaths associated with this disease are registered in the world. In the Russian Federation in 2019, 20,758 patients with a newly diagnosed renal cell carcinoma were registered; it should be noted that at the end of 2019, 177,755 patients with this diagnosis were registered. The issue of renal cell carcinoma metastasis seems to be quite relevant. The most common organs for metastatic renal cell carcinoma are lungs (up to 55 %), lymph nodes (up to 34 %), liver (up to 32 %), bones (up to 32 %), adrenal glands (up to 19 %), contralateral kidney (up to 11 %) and the brain (up to 5.7 %). The incidence of skin metastases in renal cell carcinoma ranges from 2.8 to 6.8 %, according to various authors.Our publication presents a case of treatment of a patient with a rare localization of renal cell carcinoma metastases in the external genital organs. The patient underwent palliative nephrectomy and vulvectomy. Taking into account the data on the prevalence of the disease, therapy with cabozantinib is carried out. Cabosantinib is an inhibitor of the tyrosine kinase domains of a number of growth factors, angiogenesis, abnormal bone remodeling, metastasis, and drug resistance.Ежегодно в мире регистрируют до 300 тыс. новых случаев рака почки и более 134 тыс. смертей, связанных с этим заболеванием. В России в 2019 г. были поставлены на учет 20 758 пациентов с впервые установленным почечно-клеточным раком, на конец 2019 г. на учете состояли 177 755 пациентов с данным диагнозом. Достаточно актуальной является проблема метастазирования почечно-клеточного рака. Наиболее распространенные органы для метастазирования - легкие (до 55 %), лимфатические узлы (до 34 %), печень (до 32 %), кости (до 32 %), надпочечники (до 19 %), контралатеральная почка (до 11 %) и головной мозг (до 5,7 %). Частота кожных метастазов при почечно-клеточном раке колеблется от 2,8 до 6,8 %, по мнению разных авторов.  В настоящей статье представлен случай лечения пациентки с редкой локализацией метастазов почечно-клеточного рака в наружных половых органах. Пациентка перенесла паллиативную нефрэктомию и вульвэктомию. С учетом данных о распространенности заболевания проводится терапия кабозантинибом. Кабозантиниб - ингибитор тирозинкиназных доменов ряда факторов роста, ангиогенеза, абнормального ремоделирования кости, метастазирования, а также лекарственной устойчивости.

Последовательное назначение противоопухолевой лекарственной терапии у пациентки с первично-множественным метахронным раком тела матки и раком молочной железы

Breast cancer (BC) is a heterogeneous disease characterized by the presence or absence of membrane receptor overexpression on tumor cells that correlates with the disease prognosis. Understanding of the patterns and mechanisms of tumor progression gained through clinical experience of managing BC patients is important. The treatment strategy depends on the hormone receptor status of the tumor, the HER2 / neu expression, and the proliferative activity level. A clinical case of advanced luminal A breast cancer is reported, and the rationale for sequential treatment strategy is provided taking into account the clinical situation and clinical course of the disease. Adequate endocrine therapy for hormone-positive metastatic BC provides long-term tumor control like in this case, as well as a high quality of life over the entire course of sequential treatment with anticancer drugs.Рак молочной железы (РМЖ) — гетерогенное заболевание, для которого характерно наличие или отсутствие гиперэкспрессии рецепторов на поверхности опухолевых клеток, что коррелирует с прогнозом заболевания. Важным является понимание особенностей и механизмов опухолевой прогрессии, полученное, в том числе, из клинического опыта ведения пациентов с РМЖ. Исходя из гормонального статуса опухоли, наличия или отсутствия экспрессии рецепторов HER2/neu, а также уровня пролиферативной активности определяется тактика лечения. В статье представлено описание клинического случая пациентки с распространенным люминальным А подтипом РМЖ, обоснована последовательная стратегия лечения с учетом клинической ситуации и особенностей течения заболевания. Рациональное назначение эндокринотерапии при гормоноположительном метастатическом РМЖ позволяет достичь длительного контроля над опухолью. На клиническом примере при последовательном назначении противоопухолевых лекарственных препаратов достигнут длительный контроль над опухолью и высокое качество жизни на протяжении всего периода лечения

Fractal and Computational Geometry for Generalizing Cartographic Objects

We present an algorithm for simplifying linear cartographic objects and results obtained with a computer program implementing this algorithm.</p

Fractal and Computational Geometry for Generalizing Cartographic Objects

We present an algorithm for simplifying linear cartographic objects and results obtained with a computer program implementing this algorithm