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81.
R. E. Bullock 《辐射效应与固体损伤》2013,168(2):107-112
Two types of commercially available carbon fibers (high tensile strength, HTS, and high modulus, HMS) were irradiated in the Ground Test Reactor in environments of air and of liquid nitrogen (LN2). The tensile strength of HTS fibers irradiated in air increased sharply above a fast-neutron fluence of 6 × 1017 n/cm2 (E> 1 MeV) and was 17 per cent greater than the strength of unirradiated control fibers at a fluence of 8.5 × 1017 n/cm2, but then the strengrh began to decrease for additional neutron exposure in air and fell 25 per cent below the control strength at the highest fluence of 4.5 × 1018 n/cm2. However, when irradiated in LN2 where surface oxidation did not take place, the room-temperature strength of HTS fibers continued to increase beyond 8.5 × 1017 n/cm2 and became almost 30 per cent greater than the control strength for a fluence of 3 × 1018 n/cm2. The tensile strength of HMS fibers irradiated in air increased slowly but steadily with neutron exposure and was only 4 per cent greater than the control strength at the highest fluence of 4.5 × 1018 n/cm2; the room-temperature strength of the HMS fibers decreased by 13 per cent when irradiated to a fluence of 3 × 1018 n/cm2 in LN2. 相似文献
82.
Raman spectroscopy can detect conformational changes in collagen structures and these findings are reviewed in this article. More specifically, some progressive diseases are mainly caused by alterations of collagen molecules but what is occurring at the biochemical level of this complex molecule usually remains unclear. While it may be true that a number of analytical techniques can analyze collagen, most of them have a series of limitations that limit their applicability to a wide range of samples. To understand in more detail the progression of a disease due to changes in the collagen structure, a technique that can detect subtle alterations at the biochemical level is needed. Raman spectroscopy is a label-free and noninvasive technique that can easily pick up on any conformational changes reflected primarily at the lipids, amides and proline and hydroxyproline regions. This review is the first compilation of studies of conformational changes in collagen molecules, providing help to understand changes in collagen biochemistry that can be of relevance to the human wound healing, ageing and pathologies. 相似文献
83.
D. Bullock 《Commentarii Mathematici Helvetici》1997,72(4):521-542
Let M be a compact orientable 3-manifold. The set of characters of SL
2()-representations of forms a closed affine algebraic set. We show that its coordinate ring is isomorphic to a specialization of the Kauffman bracket
skein module, modulo its nilradical. This is accomplished by realizing the module as a combinatorial analog of the ring in
which tools of skein theory are exploited to illuminate relations among characters. We conclude with an application, proving
that a small manifold's specialized module is necessarily finite dimensional.
Received: April 18, 1996 相似文献
84.
An estimate of the low wavenumber component of surface turbulence shear stress as a function of frequency has been obtained
through measurements of the correlations of the longitudinal component of turbulence velocity made close to the surface at
y
+=7. The data were acquired in a fully-developed turbulent pipe flow at a Reynolds number (based on centreline velocity and
pipe diameter) of 268000, using two single hot-wire anemometer probes. A novel data analysis procedure has been introduced
to establish the accuracy limits of the low wavenumber turbulence energy estimate for frequencies in the similarity regime
of wall turbulence and the results are compared with other measurement techniques.
Received: 18 November 1993/Accepted: 21 April 1997 相似文献
85.
86.
Papri Bhattacharya Zachariah M. Heiden Geoffrey M. Chambers Samantha I. Johnson R. Morris Bullock Michael T. Mock 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11744-11750
Catalysts for the oxidation of NH3 are critical for the utilization of NH3 as a large‐scale energy carrier. Molecular catalysts capable of oxidizing NH3 to N2 are rare. This report describes the use of [Cp*Ru(PtBu2NPh2)(15NH3)][BArF4], (PtBu2NPh2=1,5‐di(phenylaza)‐3,7‐di(tert‐butylphospha)cyclooctane; ArF=3,5‐(CF3)2C6H3), to catalytically oxidize NH3 to dinitrogen under ambient conditions. The cleavage of six N?H bonds and the formation of an N≡N bond was achieved by coupling H+ and e? transfers as net hydrogen atom abstraction (HAA) steps using the 2,4,6‐tri‐tert‐butylphenoxyl radical (tBu3ArO.) as the H atom acceptor. Employing an excess of tBu3ArO. under 1 atm of NH3 gas at 23 °C resulted in up to ten turnovers. Nitrogen isotopic (15N) labeling studies provide initial mechanistic information suggesting a monometallic pathway during the N???N bond‐forming step in the catalytic cycle. 相似文献
87.
88.
Olivier E. Nonga Darja Lavogina Erki Enkvist Katrin Kestav Apirat Chaikuad Sarah E. Dixon-Clarke Alex N. Bullock Sergei Kopanchuk Taavi Ivan Ramesh Ekambaram Kaido Viht Stefan Knapp Asko Uri 《Molecules (Basel, Switzerland)》2021,26(14)
We performed an X-ray crystallographic study of complexes of protein kinase PIM-1 with three inhibitors comprising an adenosine mimetic moiety, a linker, and a peptide-mimetic (d-Arg)6 fragment. Guided by the structural models, simplified chemical structures with a reduced number of polar groups and chiral centers were designed. The developed inhibitors retained low-nanomolar potency and possessed remarkable selectivity toward the PIM kinases. The new inhibitors were derivatized with biotin or fluorescent dye Cy5 and then applied for the detection of PIM kinases in biochemical solutions and in complex biological samples. The sandwich assay utilizing a PIM-2-selective detection antibody featured a low limit of quantification (44 pg of active recombinant PIM-2). Fluorescent probes were efficiently taken up by U2OS cells and showed a high extent of co-localization with PIM-1 fused with a fluorescent protein. Overall, the developed inhibitors and derivatives represent versatile chemical tools for studying PIM function in cellular systems in normal and disease physiology. 相似文献
89.
James Bullock Andrew Thomson Andrés Cuevas Boris Veith Jan Schmidt Ari Karkkainen 《固体物理学:研究快报》2013,7(8):530-533
Low refractive index polymer materials have been investigated with a view to form the back surface mirror of advanced silicon solar cells. SiOx:H or AlOy SiOx:H polymer films were spun on top of an ultra‐thin (<10 nm) atomic‐layer‐deposited (ALD) Al2O3 layer, itself deposited on low‐resistivity (1 Ω cm) p‐type crystalline silicon wafers. These double‐layer stacks were compared to both ALD Al2O3 single layers and ALD Al2O3/plasma‐enhanced chemical vapour deposited (PECVD) SiNx stacks, in terms of surface passivation, firing stability and rear‐side reflection. Very low surface recombination velocity (SRV) values approaching 3 cm/s were achieved with ALD Al2O3 layers in the 4–8 nm range. Whilst the surface passivation of the single ALD Al2O3 layer is maintained after a standard firing step typical of screen printing metallisation, a harsher firing regime revealed an enhanced thermal stability of the ALD Al2O3/SiOx:H and ALD Al2O3/AlOy SiOx:H stacks. Using simple two‐dimensional optical modelling of rear‐side reflection it is shown that the low refractive index exhibited by SiOx:H and AlOy SiOx:H results in superior optical performance as compared to PECVD SiNx, with gains in photogenerated current of ~0.125 mA/cm2 at a capping thickness of 100 nm. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
90.
Dial BE Rasberry RD Bullock BN Smith MD Pellechia PJ Profeta S Shimizu KD 《Organic letters》2011,13(2):244-247
A molecular rotor was designed in which the rate of rotation is accelerated by guest complexation. The binding of an acetate guest to the urea groups lowers the barrier of the adjacent C(aryl)-N(imide) bond by 2 to 4 kcal/mol. This behavior is in contrast to most molecular rotors in which guest complexation slows rotation. 相似文献