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

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.]

An Investigation of Methanol Anomalous Diffusion in Mesoporous Silica

Methanol transport in mesoporous silica is investigated. It is demonstrated that usual approach based on the second Fick’s law fails describing the experimental kinetic data. Contrary, the solution of the time-fractional diffusion equation fits the experimental data in a fairly good manner. Obtained value of the fractional order reveals the presence of fast super-diffusive regime of transport.Keywords: diffusion, anomalous diffusion, fractional diffusion, super-diffusion, silica, methanol.</p

Water evaporation particularities in the process of forest fire extinguishing

Numerical simulation of water massif motion through the high temperature gases corresponding to the typical conditions of forest fires was carried out. Maximal values of part by volume of liquid evaporating from water massif under its motion through the flaming burning area were determined when solving the heat and mass transfer problem under the conditions of endothermic phase transformations. Influence of liquid phase transition heat on the heat and mass transfer conditions on the track of water massif was determined. The expediency of polydisperse interspaced in time and space atomization of water massifs under the large-scale (especially, forest fires) fire extinguishing was proved

Using Ignition of Coal Dust Produced by Different Types of Mechanical Treatment under Conditions of Rapid Heating

Experiments aimed at studying the ignition of coal dust obtained by coal disintegration in high-energy mills are performed in a tubular furnace. Effective kinetic constants of ignition of coal dust ground in a vibrational–centrifugal mill and in a disintegration mill under conditions of rapid heating are determined for the first time. It is shown that the volatile release rate depends on the method of coal grindin

Forecasting investigation of mode fire hazard of electrical overload of cable lines

The physical and predictive mathematical models of heat and mass transfer, phase transformations and chemical reaction have been developed to determine the necessary and sufficient conditions of inflammation and fire nascence at typical cable lines electrical overloads. The integral characteristics of study process complex – ignition delay times have been established according to cable lines electrical overloads modes. The temperature distributions in typical cable lines at overloads have been determined. The concentration variation characteristic ranges (which are sufficient for gas-phase ignition) of thermal decomposition components of cable sheaths at overloads have been adduced. The two-dimensional heat-and-mass transfer problem for a three-layer cable in the area of limited heat sink is solved. Thermal decomposition of the cable sheath and diffusion of thermal decomposition components and air were taken into account. Fire risk assessment of cable lines on overload in conditions of limited heat transfer is carried out. The dependence of ignition time delay for mixture of oxidized and thermal decomposition components from intensity of a current