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71.
R. A. Antonov S. P. Besshapov E. A. Bonvech V. I. Galkin T. A. Dzgatdoev A. S. Petkun D. A. Podgrudkov T. M. Roganova T. I. Sysoeva Mik. Finger Mir. Finger D. V. Chernov S. B. Shaulov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):872-874
The SPHERE-2 detector was lifted above the snow-covered surface of Lake Baikal by a captive balloon several times in 2010. The Vavilov-Cherenkov radiation of extensive air showers was measured. Preliminary results from processing the data of the SPHERE-2 experiment at various altitudes of observation are presented. 相似文献
72.
Over the past 5 years, integrated science and mathematics professional development programs for grades 4‐10 science and mathematics teachers have been designed and implemented at Wright State University. The primary goals of the programs were to enhance the science and mathematics content understanding and pedagogical knowledge of the participant teachers in order to increase teacher confidence and promote the implementation of standards‐based teaching practices in precollege classrooms. In this article, the general program structure developed and implemented over the years is discussed. Focusing on the 1999 program, evidence is presented of enhanced participant content understanding and pedagogical preparation, and specific examples of modified teacher practices are discussed. 相似文献
73.
Nuclear orientation measurements on dilute TbGd are analysed to yield the magnetic dipole and electric quadrupole moments of161Tb g.s. and multipole mixing ratios of transitions in161Dy. 相似文献
74.
The decay of Re 186 was investigated with a double focusing spectrometer and scintillation spectrometer. Four transitions were observed with energies of 122·7±0·1 keV, 137·2 keV, 632·2±1·5 keV and 768·2±1·5 keV and the relative-ray intensities 18, 246, 0·9 and 1 respectively. TheK-conversion coefficients determined for low-energy transitions are in good agreement with the theoretical values (
K
122·7
=0·53±0·05,
K
137·2
=0·44±0·02). The relative intensities of theK, L, M andN conversion lines were also determined for these transitions:KL
I
+IIL
III
M=1·20±0·201·32±0·20 1±0·150·57±0·08 for 122·7 keV transition,KL
I
+IIL
III
MN=1·57±0·081· 72±0080·70±0·030·20±0·01 for 137·2 keV transition. In the beta spectrum two groups were observed with the end points of 1076±3 keV and 939±3 keV and relative intensities 74±4% and 21±4% respectively. For the branching ofK-capture it was found that 1·5% populates the 122·7 keV level and 3·5% the ground state. The decay scheme from the present results is proposed.The authors would like to thank M. Buriánek and V. Kopiva for help in the measurements. 相似文献
75.
Despite a wide variety of biological functions, alpha-helical membrane proteins display a rather simple transmembrane architecture. Although not many high resolution structures of transmembrane proteins are available today, our understanding of membrane protein folding has emerged in the recent years. Now we begin to develop a basic understanding of the forces that guide folding and interaction of alpha-helical membrane proteins. Some structural requirements for transmembrane helix interactions are defined, and common motifs have been discovered in the recent years which can drive helix-helix interactions. Nevertheless, many open questions remain to be addressed in future studies. One general problem with investigating transmembrane helix interactions is the limited number of appropriate tools, which can be applied to investigate membrane protein folding. Only recently several new techniques have been developed and established, including genetic systems, which allow measuring transmembrane helix interactions in vitro and in vivo. In the first part of this review, we summarize several aspects of the current understanding of membrane protein folding and assembly. In the second part, we discuss genetic systems, which were developed in the recent years to measure interaction of transmembrane helices in the inner membrane of E. coli. 相似文献
76.
Using an electrochemical quartz crystal microbalance (EQCM), we have produced bubbles of nanoscopic size at the front electrode of an acoustic shear wave resonator. Nanobubbles are usually expected to increase the resonance frequency because they have a low density and, also, because a liquid slides easily at a liquid-air interface. However, the bubble-induced frequency shift in many cases was negative, which implies positive hydrodynamic thickness and reduced slippage. The explanation is based on Laplace pressure. Due to the bubbles' inherent stiffness, the space in-between neighboring bubbles may turn into an assembly of pockets which move with the underlying substrate in the same way as a solid film. If, first, the bubbles are so small that the Laplace pressure can overcome the viscous drag, and, second, the contact angle is in the range of 90°, the latter effect dominates. This interpretation was corroborated by a calculation using the finite element method (FEM). The argument as such is not limited to acoustic shear waves: hemispherical nanobubbles increase the surface drag in stationary flows in the same way. 相似文献
77.
M. Fehr A. Schnegg B. Rech K. Lips O. Astakhov F. Finger C. Freysoldt R. Bittl C. Teutloff 《Journal of Non》2012,358(17):2067-2070
Paramagnetic coordination defects in undoped hydrogenated amorphous silicon (a-Si:H) are studied using multifrequency pulsed electron-paramagnetic resonance (EPR) spectroscopy at S-, X-, Q- and W-band microwave frequencies (3.6, 9.7, 34, and 94 GHz, respectively). The improved spectral information extractable from a multifrequency fitting procedure allows us to conclude that the g tensor exhibits a rhombic splitting instead of axial symmetry. Our methods allow for precise and accurate determination of the g tensor principal values gx = 2.0079(2), gy = 2.0061(2) and gz = 2.0034(2) and their distribution parameters (g strain). 相似文献
78.
Wei‐Jun Kong Lars H. Finger Joo C. A. Oliveira Lutz Ackermann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6408-6412
Rapid access to structurally diversified polycyclic aromatic hydrocarbons (PAHs) in a controlled manner is of key significance in materials sciences. Herein, we describe a strategy featuring two distinct electrocatalytic C?H transformations for the synthesis of novel nonplanar PAHs. The combination of rhodaelectrooxidative C?H activation/[2+2+2] alkyne annulation of easily accessible boronic acids with electrocatalytic cyclodehydrogenation provided modular access to diversely substituted PAHs with electricity as a sustainable oxidant. The unique molecular topology as well as the photophysical and electronic properties of the thus obtained PAHs were fully analyzed. The unique power of this metallaelectrocatalysis method was demonstrated by the chemoselective assembly of synthetically useful iodo‐substituted PAHs. 相似文献
79.
Jens Rumschöttel Susann Baus Sabine Kosmella Dietmar Appelhans 《Composite Interfaces》2018,25(1):1-11
Polyplexes between a double-stranded Salmon DNA and hyperbranched poly(ethyleneimine) (PEI) as well as a maltosylated PEI-Mal were incorporated into a gelatin/chitosan hydrogel scaffold. Calorimetric experiments of the polyplexes show a decrease of the melting temperature in presence of PEI and a peak splitting in presence of PEI-Mal, which can be interpreted to a partial compaction of the DNA strands in presence of PEI-Mal. When the polyplexes are incorporated into a gelatin/chitosan scaffold in the swollen state, the DNA melting peaks at 90 and 93 °C, respectively, indicate in both cases the release of the DNA at the surface of the hydrogel scaffold in a more compact form. Specific interactions between the PEI-Mal shell and gelatin are responsible for the tuning of the release properties in presence of the maltose units in the hyperbranched PEI. 相似文献
80.
J. Ferencei M. Finger J. Dupák A. Jankech J. Koníček F. A. Schus J. Říkovská A. Machová D. W. Hamilton 《Czechoslovak Journal of Physics》1981,31(5):511-521
The anisotropy in the directional distribution of gamma-rays from the decay of152,154Tb oriented in a gadolinium matrix at low temperatures, has been measured at the angles of 0 and π/2 with respect to the applied magnetic field direction at temperature of (15±1) mK. Unambiguous values of spin have been deduced for several levels in152Gd. Multipole mixing ratios of many gamma-ray transitions occurring in152Gd have been found and results are compared with the similar transitions in150,154,156Gd and they are discussed in terms of the rotational-vibrational model and dynamic deformation theory based on the Strutinsky method. Our results confirm the spin value of 0 for 21·4 h isomer in154Tb and they establish the spin value of 3 for the 2277·0 and 2336·1 keV levels and the spin value of 4 for the 2416·3 keV level in154Gd. 相似文献