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81.
82.
Paul R. Stysley Demetrios Poulios Donald B. Coyle Richard B. Kay 《Optics & Laser Technology》2008,40(3):435-440
A diode-pumped, Q-switched Nd:YAG laser employing a dual-pump zig-zag slab head scheme in an unstable resonator configuration for use in space-based planetary altimetry or atmospheric LIDAR is described. The pump heads are aligned orthogonally to each other, producing a symmetric overall thermal lens that eliminates the need for an intracavity cylindrical lens and aperture. This laser has demonstrated over 100 mJ in Q-switched operation with high optical efficiency (24%), good beam quality, high pointing stability, and large operational margins for multi-billion shot lifetimes. 相似文献
83.
84.
John Pattinson Gibb Kay Sexton David Watson W. J. Ward T. Egleston O. Pufahl und K. A. Åkerblom 《Fresenius' Journal of Analytical Chemistry》1886,25(1):255-258
Ohne Zusammenfassung 相似文献
85.
This essay investigates the relationships among the metric, the connection, the curvature, and the covariant curvature derivatives in general relativity. The extent to which the connection or the curvature together, possibly with certain curvature derivatives, determines the metric is considered, as well as other related problems. Some topological aspects of the problem are included and some applications to holonomy and symmetry groups are given.This article received honorable mention from the Gravity Research Foundation for 1987. 相似文献
86.
Poly(vinylferrocene) (pVFc) homopolymer was synthesized by free radical polymerization, along with a series of pVFc-based copolymers containing either styrene, vinylanthracene or methylmethacrylate. This report details the electrochemical experiments conducted to examine the stability of the various pVFc based polymers, which is shown to be critically dependent on the extent of copolymerization. A trend was found that when the concentration of co-monomer was decreased, electrochemical stability was enhanced. Furthermore incorporation of a second monomer into the polymer chain produced a profound effect on the scan rate behaviour of the vinylferrocene moiety. As the concentration of co-monomer was decreased, the behaviour tended towards that of a diffusion controlled process. These results are of vital significance for the development of pVFc-based electrochemical sensors. 相似文献
87.
We report the preparation of hybrid self-assembled microgel beads by combining the low molecular weight gelator (LMWG) DBS-CONHNH2 and the natural polysaccharide calcium alginate polymer gelator (PG). Microgel formulations based on LMWGs are extremely rare due to the fragility of the self-assembled networks and the difficulty of retaining any imposed shape. Our hybrid beads contain interpenetrated LMWG and PG networks, and are obtained by an emulsion method, allowing the preparation of spherical gel particles of controllable sizes with diameters in the mm or μm range. Microgels based on LMWG/alginate can be easily prepared with reproducible diameters <1 μm (ca. 800 nm). They are stable in water at room temperature for many months, and survive injection through a syringe. The rapid assembly of the LMWG on cooling plays an active role in helping control the diameter of the microgel beads. These LMWG microbeads retained the ability of the parent gel to deliver the bioactive molecule heparin, and in cell culture medium this enhanced the growth of human mesenchymal stem cells. Such microgels may therefore have future applications in tissue repair. This approach to fabricating LMWG microgels is a platform technology, which could potentially be applied to a variety of different functional LMWGs, and hence has wide-ranging potential.We report microgel beads with diameters of ca. 800 nm based on interpenetrating networks of a low-molecular-weight gelator and a polymer gelator, and demonstrate their use as heparin delivery vehicles to enhance stem cell growth. 相似文献
88.
W. Simarew S. G. Menefee O. R. Overman A. Gorbatschewa H. Chr Jorgensen I. V. Hunt A. Konoplew H. Fincke C. Ehrlich R. Trommsdorff M. Asdrubali S. Hadwen R. Gwatkin F. K. Neave H. D. Kay W. R. Graham R. Aschaffenburg A. Jepsen P. Madelung Ch. Paley H. Kreker A. M. Williams May Davies S. B. Thomas G. M. Phillips W. M. Ashton G. D. Simons J. Davies B. F. Thomas L. Little H. A. Sirks G. Sjöström P. Jaulmes L. Poujol und J. A. B. Smith 《Fresenius' Journal of Analytical Chemistry》1943,126(7):282-286
Ohne Zusammenfassung 相似文献
89.
Benjamin De Bari Alexandra Paxton Dilip K. Kondepudi Bruce A. Kay James A. Dixon 《Entropy (Basel, Switzerland)》2021,23(5)
Coordination within and between organisms is one of the most complex abilities of living systems, requiring the concerted regulation of many physiological constituents, and this complexity can be particularly difficult to explain by appealing to physics. A valuable framework for understanding biological coordination is the coordinative structure, a self-organized assembly of physiological elements that collectively performs a specific function. Coordinative structures are characterized by three properties: (1) multiple coupled components, (2) soft-assembly, and (3) functional organization. Coordinative structures have been hypothesized to be specific instantiations of dissipative structures, non-equilibrium, self-organized, physical systems exhibiting complex pattern formation in structure and behaviors. We pursued this hypothesis by testing for these three properties of coordinative structures in an electrically-driven dissipative structure. Our system demonstrates dynamic reorganization in response to functional perturbation, a behavior of coordinative structures called reciprocal compensation. Reciprocal compensation is corroborated by a dynamical systems model of the underlying physics. This coordinated activity of the system appears to derive from the system’s intrinsic end-directed behavior to maximize the rate of entropy production. The paper includes three primary components: (1) empirical data on emergent coordinated phenomena in a physical system, (2) computational simulations of this physical system, and (3) theoretical evaluation of the empirical and simulated results in the context of physics and the life sciences. This study reveals similarities between an electrically-driven dissipative structure that exhibits end-directed behavior and the goal-oriented behaviors of more complex living systems. 相似文献
90.
Mark S. Oliver Kay Y. Blohowiak Reinhold H. Dauskardt 《Journal of Sol-Gel Science and Technology》2010,55(3):360-368
The mechanical reliability of hybrid films depends critically on their fracture properties which are controlled largely by
the film composition and molecular structure. We have investigated the adhesive and cohesive fracture properties of hybrid
films processed from 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetra n-propoxyzirconium (TPOZ), for which the roles of molecular structure and composition have not been well established. The influences
of film Zr/GPTMS ratio, silane crosslinking, and substrate composition on fracture resistance were quantified in terms of
the critical strain energy release rate, GC Film fracture energy was found to increase, then decrease with increasing Zr/GPTMS ratio. Removal of the epoxy rings of GPTMS
from the film was found to drastically decrease the cohesive fracture energy of the film as well as the adhesive fracture
energy of the film/epoxy interface. Finally, films deposited on silicon had much higher fracture energies compared to those
deposited onto aluminum and titanium from identical sols. FTIR, XPS, and AFM were used to characterize the film structure
and fracture surfaces. The molecular-scale mechanisms responsible for the observed trends are discussed. These results provide
new insights into the interaction between the substrate chemistry, molecular structure, and mechanical reliability of hybrid
sol-gel films. 相似文献