Focal plane transport assembly for the HEAO-B X-ray telescope

The High Energy Astronomy Observatory - Mission B (HEAO-B), an earth orbiting X-ray telescope facility capable of locating and imaging celestial X-ray sources within one second of arc in the celestial sphere, is considered. The Focal Plane Transport Assembly (FPTA) is one of the basic structural elements of the three thousand pound HEAO-B experiment payload. The FPTA is a multifunctional assembly which supports seven imaging X-ray detectors circumferentially about a central shaft and accurately positions any particular one into the focus of a high resolution mirror assembly. A drive system, position sensor, rotary coupler, and detent alignment system, all an integral part of the rotatable portion which in turn is supported by main bearings to the stationary focal plane housing are described

Interfacial architecture on the fractal support: polycrystalline gold films as support for self-assembling monolayers

Multifractal analysis is performed for description of the surface topography of thin polycrystalline gold film. Its structure was modified by annealing at different temperatures in the range 20÷200 ⁰C and films were imaged by Atomic Force Microscopy. Image was analyzed as a collection of layers taken parallel to the mean surface. Fractal subsets with different scaling properties were described by multifractal divergence (e.g. the difference between maximal and minimal values of the f (a) spectrum). This allowed to highlight the effect of the temperature of film annealing on the surface structure. We found that fractal diversity jumps down in the temperature range 130÷140 ⁰C. Therefore, phase transition occurs in the system. Below the temperature of the phase transition the surface topography is characterized by high roughness and existence of small-scale irregularities. At critical temperature the surface structure undergoes morphological transition caused by melting of small-scale irregularities. The melting also results in a decrease of the surface roughness due to the flowing down of gold crystallites. A notable feature of the approach is its ability to highlight a possible influence of substrate structure on the adsorption/self-assembling processes at the interface, which may be disturbed by the surface irregularities. The typical and expressive example taken from the self-assembling on the polycrystalline substrate. Particularly, substrate topography determines an order of thiols layers resulting in peculiarities of chemical functionality of obtained material. It was shown that formation of well-ordered monolayers of ω-substituted alkanethiols on gold films occurs only if the freshly evaporated gold films were annealed at temperature more than ca.120 ⁰C. The analysis of surface peculiarities allows suggesting that this behavior is caused by disappearance of short-scale multifractal structures. Therefore, the multifractal analysis opens a new avenue for both characterization and direct prediction of surface properties. Particularly, it gives a hint regarding a formation of the Euclidean two-imensional structures at the multifractal substrates

Diarylethene moiety as an enthalpy-entropy switch: photoisomerizable stapled peptides for modulating p53/MDM2 interaction

Analogs of the known inhibitor (peptide pDI) of the p53/MDM2 protein–protein interaction are reported, which are stapled by linkers bearing a photoisomerizable diarylethene moiety. The corresponding photoisomers possess significantly different affinities to the p53-interacting domain of the human MDM2. Apparent dissociation constants are in the picomolar-to-low nanomolar range for those isomers with diarylethene in the “open” configuration, but up to eight times larger for the corresponding “closed” isomers. Spectroscopic, structural, and computational studies showed that the stapling linkers of the peptides contribute to their binding. Calorimetry revealed that the binding of the “closed” isomers is mostly enthalpy-driven, whereas the “open” photoforms bind to the protein stronger due to their increased binding entropy. The results suggest that conformational dynamics of the protein-peptide complexes may explain the differences in the thermodynamic profiles of the binding

Клинические наблюдения гигантоклеточного гепатита у детей

Giant cell hepatitis is characterized, by inflammation and large multinucleated. hepatocytes in hepatic parenchyma It is an unusual hepatocytes response to various noxious stimuli, characterized, by presence of multinucleated cells in liver with generally dismal clinical outcome. Giant cell hepatitis is commonly reported, in neonatal and. infantile liver diseases but rarely in adults (postinfantile giant cell hepatitis). Giant cell hepatitis is associated, with many diseases, including drugs toxicity, viral and. autoimmune liver diseases, with autoimmune hepatitis being the most prevalent. We report some clinical cases of giant cell hepatitis with review of literature regarding various etiological agents and their respective prognostic outcome.Гигантоклеточный гепатит, характеризуется наличием воспалительного инфильтрата и гигантских многоядерных клеток в печеночной паренхиме. Гигантоклеточная трансформация представляет, собой необычный ответ, гепатоцитов на различные повреждающие факторы, обычно с неблагоприятным, клиническим, исходом. Гигантоклеточный гепатит, обычно наблюдается при неонатальных и инфантильных заболеваниях печени и редко у взрослых (постинфантильный гигантоклеточный гепатит). Гигантоклеточный гепатит, ассоциируется со многими заболеваниями, включая токсическое воздействие лекарственных средств, вирусные и аутоиммунные заболевания печени. Наиболее распространенным, является аутоиммунный гепатит. Мы сообщаем, о нескольких клинических случаях гигантоклеточного гепатита с обзором, литературы, относительно различных этиологических агентов и их соответствующих прогностических результатов

Fluorescent amino acids as versatile building blocks for chemical biology

Fluorophores have transformed the way we study biological systems, enabling non-invasive studies in cells and intact organisms, which increase our understanding of complex processes at the molecular level. Fluorescent amino acids have become an essential chemical tool because they can be used to construct fluorescent macromolecules, such as peptides and proteins, without disrupting their native biomolecular properties. Fluorescent and fluorogenic amino acids with unique photophysical properties have been designed for tracking protein–protein interactions in situ or imaging nanoscopic events in real time with high spatial resolution. In this Review, we discuss advances in the design and synthesis of fluorescent amino acids and how they have contributed to the field of chemical biology in the past 10 years. Important areas of research that we review include novel methodologies to synthesize building blocks with tunable spectral properties, their integration into peptide and protein scaffolds using site-specific genetic encoding and bioorthogonal approaches, and their application to design novel artificial proteins, as well as to investigate biological processes in cells by means of optical imaging. [Figure not available: see fulltext.]