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21.
Konstantin Kovler 《Construction and Building Materials》2009,23(1):246-253
The advantages of utilization of coal fly ash, phosphogypsum and some other industrial by-products in construction are discussed, as well as the technological and environmental problems caused by an elevated content of chemical/radioactive contaminants. Radiological aspects and legislation issues are analyzed. The tendency to develop stricter environmental norms observed in the last years in both national and international scale is noted. The reasons and possible methods of solving the difficulties with the application of legislation rules and radiation controls in construction industry are discussed. As an example, an experience with the new Israeli Standard 5098 regulating radioactivity in building products is reported. The principles of this standard are analyzed and compared to the Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials Principles of Radiation (Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials, Radiation Protection Report RP-112, EC, European Commission, Luxembourg, 1999) and other existing national standards and guidelines in the field. 相似文献
22.
Ethylene polymerization with homogeneous and heterogeneous catalysts based on bis(4‐fluorophenyl)methyl‐substituted bis(imino)pyridyliron complexes
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Nina V. Semikolenova Wenjuan Zhang Vladimir A. Zakharov Konstantin P. Bryliakov Wen‐Hua Sun 《应用聚合物科学杂志》2015,132(42)
A series of bis(4‐fluorophenyl)methyl‐substituted bis(imino)pyridyliron chloride complexes were immobilized on oxide supports. The kinetics of ethylene polymerization by both homogeneous and heterogeneous systems was followed, the catalysts mostly demonstrating high activities. The effect of the ligands nature and reaction conditions on the catalytic activities and molecular weights of the resultant polyethylenes was examined. In contrast to homogeneous systems, the supported iron complexes were found to exhibit high and stable activity upon activation with triisobutyl aluminium, producing high‐molecular‐weight polyethylene with good morphology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42674. 相似文献
23.
Development of Saturable Absorbers for Laser Passive Q‐Switching near 1.5 μm Based on Transparent Ceramic Co2+:MgAl2O4
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Adrian Goldstein Pavel Loiko Zeev Burshtein Nikolai Skoptsov Ilya Glazunov Ehud Galun Nikolai Kuleshov Konstantin Yumashev 《Journal of the American Ceramic Society》2016,99(4):1324-1331
We describe the development of a reasonable cost Co2+:MgAl2O4 transparent ceramic plates fabrication technology that allows the producing of parts functioning as passive laser Q‐switches in the 1.3–1.7 μm domain. The main relevant material characteristics were measured. The absorption band, positioned between 1.2 and 1.7 μm, is typical of the 4A2 (4F) → 4T1 (4F) transition of Co2+ substituting Mg2+ ions in their Td symmetry sites. The measured ground‐state absorption cross section σgs = 2.9 × 10?19 cm2, saturation contrast γ = 0.12, and depleted ground‐state recovery time τ2 = 110–430 ns render such parts suitable for the intended application. The radiative lifetime was estimated as . The spin‐orbit splitting constant was estimated as ξSL??150 cm?1 for the 4F parent ground state, and ξSL ? –575 cm?1 for the 4P parent excited state. Obtained specimens had a transmission of ~80% (t = 2 mm, λ = 600 nm) and included some opaque, white spots. Further improvement of host optical transmission and resistance to laser damage are necessary. 相似文献
24.
Jeremy A. Nestele Anne-Katrin Rohlfing Valerie Dicenta Alexander Bild Daniela Eißler Frederic Emschermann Marcel Kremser Konstantin Krutzke Tilman E. Schffer Oliver Borst Moran Levi Netanel Korin Meinrad Paul Gawaz 《International journal of molecular sciences》2022,23(1)
Traditional antithrombotic agents commonly share a therapy-limiting side effect, as they increase the overall systemic bleeding risk. A novel approach for targeted antithrombotic therapy is nanoparticles. In other therapeutic fields, nanoparticles have enabled site-specific delivery with low levels of toxicity and side effects. Here, we paired nanotechnology with an established dimeric glycoprotein VI-Fc (GPVI-Fc) and a GPVI-CD39 fusion protein, thereby combining site-specific delivery and new antithrombotic drugs. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles, NP-BSA, NP-GPVI and NP-GPVI-CD39 were characterized through electron microscopy, atomic force measurements and flow cytometry. Light transmission aggregometry enabled analysis of platelet aggregation. Thrombus formation was observed through flow chamber experiments. NP-GPVI and NP-GPVI-CD39 displayed a characteristic surface coating pattern. Fluorescence properties were identical amongst all samples. NP-GPVI and NP-GPVI-CD39 significantly impaired platelet aggregation. Thrombus formation was significantly impaired by NP-GPVI and was particularly impaired by NP-GPVI-CD39. The receptor-coated nanoparticles NP-GPVI and the bifunctional molecule NP-GPVI-CD39 demonstrated significant inhibition of in vitro thrombus formation. Consequently, the nanoparticle-mediated antithrombotic effect of GPVI-Fc, as well as GPVI-CD39, and an additive impact of CD39 was confirmed. In conclusion, NP-GPVI and NP-GPVI-CD39 may serve as a promising foundation for a novel therapeutic approach regarding targeted antithrombotic therapy. 相似文献
25.
26.
Vladimir P. Sotskov Nikita A. Pospelov Viktor V. Plusnin Konstantin V. Anokhin 《International journal of molecular sciences》2022,23(2)
Hippocampal place cells are a well-known object in neuroscience, but their place field formation in the first moments of navigating in a novel environment remains an ill-defined process. To address these dynamics, we performed in vivo imaging of neuronal activity in the CA1 field of the mouse hippocampus using genetically encoded green calcium indicators, including the novel NCaMP7 and FGCaMP7, designed specifically for in vivo calcium imaging. Mice were injected with a viral vector encoding calcium sensor, head-mounted with an NVista HD miniscope, and allowed to explore a completely novel environment (circular track surrounded by visual cues) without any reinforcement stimuli, in order to avoid potential interference from reward-related behavior. First, we calculated the average time required for each CA1 cell to acquire its place field. We found that 25% of CA1 place fields were formed at the first arrival in the corresponding place, while the average tuning latency for all place fields in a novel environment equaled 247 s. After 24 h, when the environment was familiar to the animals, place fields formed faster, independent of retention of cognitive maps during this session. No cumulation of selectivity score was observed between these two sessions. Using dimensionality reduction, we demonstrated that the population activity of rapidly tuned CA1 place cells allowed the reconstruction of the geometry of the navigated circular maze; the distribution of reconstruction error between the mice was consistent with the distribution of the average place field selectivity score in them. Our data thus show that neuronal activity recorded with genetically encoded calcium sensors revealed fast behavior-dependent plasticity in the mouse hippocampus, resulting in the rapid formation of place fields and population activity that allowed the reconstruction of the geometry of the navigated maze. 相似文献
27.
28.
Pavel P. Fedorov Vera Y. Proydakova Sergey V. Kuznetsov Valery V. Voronov Alexandr A. Pynenkov Konstantin N. Nishchev 《Journal of the American Ceramic Society》2020,103(5):3390-3400
The thermal analysis and X-ray powder diffraction studies of the Li2SO4–Na2SO4 system, including the high-temperature X-ray diffraction technique, have elucidated four phases of variable composition: three solid solutions based on the α-Li2SO4, α-Na2SO4, and α-LiNaSO4 high-temperature polymorphs, and a low-temperature β-LiNaSO4 phase. α-Na2SO4-Base solid solution disintegrates into two phases via a monotectoid phase transformation. It is quite probable that the monotectoid process is related to the conversion of the second-order phase transition to the first-order phase transition. 相似文献
29.
Levitsky K Boersma MD Ciolli CJ Belshaw PJ 《Chembiochem : a European journal of chemical biology》2005,6(5):890-899
Investigations on the scope and utility of exo-mechanism proximity-accelerated reactions in engineered receptor-ligand systems are reported. We synthesized a series of electrophilic cyclosporin (CsA) derivatives by varying electrophiles and linker lengths, prepared a series of nucleophilic cysteine mutations on the surface of cyclophilin A (Cyp), and examined their reactivity and specificity in proximity-accelerated reactions. Acrylamide and epoxide electrophiles afforded useful reactivity and high specificity for alkylation of engineered receptors in Jurkat cell extracts. We found that remote cysteines (>17 A from the ligand) could be alkylated with useful rates under physiological conditions. The results from mutations of the receptor surface suggest that the dominant factors governing the rates of proximity-accelerated reactions are related to the local environment of the reactive group on the protein surface. This study defines several parameters affecting reactivity in exo-mechanism proximity-accelerated reactions and provides guidance for the design of experiments for biological investigations involving proximity-accelerated reactions. 相似文献
30.
The susceptibility of 16 noncompetitive cardiac pacemakers to radiation from a powerful radar system was investigated in the laboratory and in the vicinity of its prototype. From comparative in vitro tests in air, fat, water, and saline it was concluded that only tests in fat or air represent the worst case condition after implantation. In air all pacemakers showed signs of interference at pulse power densities between 0.025 mW/cm2 and 62.5 mW/CM2. Three of six implanted pacemakers were triggered or inhibited depending on their mode of operation when tested at a location 1.2 km away from the radar station by the radar beam occurring every 5.5 sec. Because interfering radiation can enter the pacemaker circuitry directly along the electrode, acting as an antenna, metal encapsulation of the pulse generator does not provide sufficient shielding against microwave radiation. However, pacemakers modified by metal encapsulation and a low-pass filter at the electrode remained undistrubed at pulse power densities of greater than 10 W/cm2 when tested under worst case condition in air. 相似文献