771 research outputs found
Особливості змісту права громадян на екологічну безпеку
В статье сделан анализ содержания права граждан на экологическую безопасность, определяется момент, с которого право на экологическую безопасность считается нарушенным
Exotics and all that
This invited contribution summarizes some of the more important aspects of
exotics. We review theoretical expectations for exotic and nonexotic hybrid
mesons, and briefly discuss the leading experimental candidate for an exotic,
the pi_1(1600).Comment: 4 pages. Invited contribution to Electron-Nucleus Scattering VII,
Elba, 24-28 June 200
Alpha-decay Rates of Yb and Gd in Solar Neutrino Detectors
The -decay rates for the nuclides Yb
and Gd have been estimated from transmission probabilities
in a systematic -nucleus potential and from an improved fit to
-decay rates in the rare-earth mass region. Whereas -decay of
Gd in natural gadolinium is a severe obstacle for the use of gadolinium
as a low-energy solar-neutrino detector, we show that
-decay does not contribute significantly to the background in a
ytterbium detector. An extremely long -decay lifetime of Yb
is obtained from calculation, which may be close to the sensitivity limit in a
low-background solar neutrino detector.Comment: 12 pages, 1 figure; An author name was correcte
Возможность прогнозирования клеточного типа увеальных меланом без использования инвазивных методов диагностики
Резюме. С помощью дискриминантного анализа установлена возможность определения клеточного типа меланомы увеального тракта в процессе проведения комбинированного (фотокоагуляция + брахитерапия) лечения. Разработана высокозначимая (l = 0,08; р = 0,002) дискриминантная модель, включающая ряд клинических (степень пигментации, пол, скорость роста меланомы) и иммунологических (количество Т- и В-лимфоцитов, процент Т-хелперов и др.) показателей. Особое место в модели занимают признаки, в наибольшей степени отражающие биологические особенности увеальных меланом различного клеточного состава, а именно — скорость изменения размера опухоли в процессе лечения и изменение показателей клеточного иммунитета.
Ключевые слова: увеальная меланома, клеточный тип, клинико-морфологические, иммунологические показатели, дискриминантный анализ.Summary. Application of the discriminant analysis shows that it is possible to define the cell type of melanoma of uveal tract of the eye in the process of combined (photocoagulation + brachytherapy) treatment. A highly reliable (l= 0,08; р = 0,002) discriminant model was elaborated, involving a number of both clinical (pigmentation level, gender, melanoma growth rate) and immunological (number of T and B lymphocytes, T helper rate, etc.) indicators. In this model, especially important are those traits that most pronouncedly reflect the biological peculiarities of uveal melanomas of various cellular compositions, namely — the pace of tumor size growth in the process of treatment and changes in cell immunity indicators.
Key Words: uveal melanoma, cell type, clinical and morphological, immunological indicators, discriminant analysis
The study of titanium oxynitride coatings solubility deposited by reactive magnetron sputtering
To improve hemocompatibility of cardiovascular stents the coatings based on titanium oxides and oxynitrides were used. In the present work the morphology, surface properties (wettability and surface energy), and in vitro solubility of the ternary system Ti-N-O coating were investigated. Experimentally, low dissolution rate of the coating in saline NaCl (0,9%) was confirmed. Instrumental methods of quantitative analysis (XRF, AES) revealed that the Ti-N-O coating is chemical-resistant and does not change the qualitative and quantitative composition of body fluids
New insight into the catalytic mechanism of bacterial MraY from enzyme kinetics and docking studies
Phospho-MurNAc-pentapeptide translocase (MraY) catalyzes
the synthesis of Lipid I, a bacterial peptidoglycan precursor. As such, MraY is essential for bacterial survival and therefore is an ideal target for developing novel antibiotics. However, the understanding of its catalytic mechanism, despite the recently determined
crystal structure, remains limited. In the present study, the kinetic properties of Bacillus subtilis MraY (BsMraY) were investigated by fluorescence enhancement using dansylated UDP-Mur-NAc-pentapeptide and heptaprenyl phosphate (C35-P, shortchain homolog of undecaprenyl phosphate, the endogenous substrate ofMraY)as second substrate. Varying the concentrations of both of these substrates and fitting the kinetics data to two-substrate
models showed that the concomitant binding of both UDPMurNAc-pentapeptide-DNS and C35-P to the enzyme is required before the release of the two products, Lipid I andUMP.We built a model of BsMraY and performed docking studies with the substrate C35-P to further deepen our understanding of how MraY accommodates this lipid substrate. Based on these modeling studies, a novel catalytic role was put forward for a fully conserved histidine residue inMraY(His-289 in BsMraY), which has been experimentally confirmed to be essential for MraY activity. Using the current model of BsMraY, we propose that a small conformational change is necessary to relocate the His-289 residue, such that the translocase reaction can proceed via a nucleophilic attack of the phosphate moiety of C35-P on bound UDP-MurNAc-pentapeptide
A Two-Tailed Phosphopeptide Crystallizes to Form a Lamellar Structure
The crystal structure of a designed phospholipid-inspired amphiphilic phosphopeptide at 0.8 Å resolution is presented. The phosphorylated β-hairpin peptide crystallizes to form a lamellar structure that is stabilized by intra- and intermolecular hydrogen bonding, including an extended β-sheet structure, as well as aromatic interactions. This first reported crystal structure of a two-tailed peptidic bilayer reveals similarities in thickness to a typical phospholipid bilayer. However, water molecules interact with the phosphopeptide in the hydrophilic region of the lattice. Additionally, solid-state NMR was used to demonstrate correlation between the crystal structure and supramolecular nanostructures. The phosphopeptide was shown to self-assemble into semi-elliptical nanosheets, and solid-state NMR provides insight into the self-assembly mechanisms. This work brings a new dimension to the structural study of biomimetic amphiphilic peptides with determination of molecular organization at the atomic level
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