排序方式: 共有27条查询结果,搜索用时 15 毫秒
1.
The effect of different shot-peening treatments on the cyclic fluctuating bending fatigue behavior of a new aluminum-lithium alloy (the 2091) has been investigated. The residual-stresses in-depth profiles have been defined just after the shot peening using mainly the X-ray diffraction method. To reach a given depth inside the material, the surface layer was removed by electro-polishing. The acquired data had to be then corrected in order to account for the redistribution of the stresses during the polishing. Furthermore, this alloy contains up to 15-percent intermetallic precipitates. Moreover, the X-rays penetrate deeply inside the material (23 m). For these reasons, a special procedure, based on a self-consistent micromechanical scheme, has been developed to correct the acquired data. The stress profiles obtained by this procedure are compared to those obtained by other mechanical experimental methods and those calculated by a theoretical shot-peening method. Shot peening improves the life of the material but the surface residual stresses are partially released during the first cycles of fatigue and are then quickly stabilized.Paper was presented at the 1994 SEM International Conference on Residual Stresses (ICRS4) held in Baltimore, MD on June 8–10. 相似文献
2.
3.
This paper describes the stereoselective outcome of the intramolecular Diels-Alder furan (IMDAF) reaction of substituted (2S,3S)-ethanolamides 9-13, which were synthesised from a furyl substituted cyanohydrin. The latter was obtained from 2-furaldehyde with high enantioselectivity by an oxynitrilase catalysed addition of hydrogen cyanide. The stereochemistry of the IMDAF products was shown to be dependent on the size of the ethanolamide substituents R. Small substituents (H, Me, CN) gave exclusively exo-cycloaddition, whereas more bulky ones (Ph, Et) gave both evo- and endo-addition, the larger phenyl substituent giving a high endo-exo-ratio. 相似文献
4.
5.
Inside Cover: A Dynamic and Responsive Host in Action: Light‐Controlled Molecular Encapsulation (Angew. Chem. Int. Ed. 52/2016) 下载免费PDF全文
6.
J. S. Alencar S. Pietri M. Culcasi C. Orneto P. Piccerelle J. P. Reynier H. Portugal A. Nicolay J. Kaloustian 《Journal of Thermal Analysis and Calorimetry》2009,98(1):133-143
Dry emulsions prepared from saccharose (SAC), Labrafil? M 1944 CS, sesamol (SEOH), and hydroxypropylmethylcellulose (HPMC) or sodium caseinate (SC) by grinding or dissolution, and
different desiccation techniques (spray (SD)- or freeze (FD)-drying, or heating at 60 °C) were investigated to determine possible
interactions between mixture components. The goal of this study was to determine the best formulation which will regenerate
perfectly, after water dilution of dry emulsions, the initial liquid emulsion with the same characteristics that before drying.
The morphological state of SAC and dry emulsions were determined by scanning electron microscopy analysis (SEM) analysis.
Glass transition temperature, and melting (endothermic), decomposition (endothermic), oxidation (exothermic) peak temperatures
and enthalpies were measured by differential scanning calorimetry (DSC). The antioxidant activity of emulsions was evaluated
through their ability to reduce 1,1-diphenyl-2-picrylhydrazil (DPPH) free radical. SEM analysis showed that SD-prepared, SC-containing
dry emulsions formed better spherical particles with smooth surface at about 5 μm diameter as compared to emulsion containing
HPMC. These former emulsions also showed more thermal stability by DSC. The combined results of the three analytical techniques
emphasized the importance of the dry emulsion process regarding the efficiency and the thermal stability of antioxidant substances.
A specific physical and/or chemical combination (such as hydrogen bond) sufficiently stable, at about 150 °C, could be suggested
when the technique used for dry emulsion preparation was SD. After water dilution, this dry emulsion obtained from quaternary
mixture: SAC, Labrafil?, SEOH and SC, will regenerate the initial liquid emulsion with the same characteristics that before drying. 相似文献
7.
N. Jegenyes J. Etchepare B. Reynier D. Scuderi A. Dos-Santos Z. Tóth 《Applied Physics A: Materials Science & Processing》2008,91(3):385-392
The evolution of a fs laser generated plume on copper was studied by dual laser pulses. The plume generated by the first pulse
(620 nm) was excited by the second, delayed pulse (310 nm). The actual state of the plume was monitored by detecting the intensities
of the emitted light and the reflected delayed pulse from the interaction range, i.e. 0–150 μm above the surface. Four peaks
were observed in the 0–1400 ps time range and assigned to appearance of electrons, ions, atomic species and nanoparticles.
Accordingly, the timing of the creation and ejection of these species was determined. By integrating the intensity of the
nanoparticle peak, the production yield of the nanoparticles and its dependence on the ablating laser fluence was calculated.
The ablation products were deposited on a Si substrate, too, and analyzed by atomic force microscopy and scanning electron
microscopy. The results of the deposition and the dual-pulse experiments are in good agreement with the theory.
PACS 52.38.Mf; 79.20.Ds; 61.80.Ba 相似文献
8.
9.
A technique for simulating large optical path lengths by use of digital delay buffers is presented. This technique is used to generate a synthetic interferometer with one arm having an arbitrary length. The response of the interferometer to phase and frequency modulation is measured and found to be in agreement with predictions. This technique could be used to simulate long-baseline interferometric space missions such as the Laser Interferometer Space Antenna. 相似文献
10.
Dr. Jesús del Barrio Dr. Reynier Suardíaz Dr. Daniel F. Ryan Dr. Edina Rosta Prof. Dr. Oren A. Scherman 《Angewandte Chemie (International ed. in English)》2016,55(52):16096-16100
The rational design of a flexible molecular box, oAzoBox 4+, incoporating both photochromic and supramolecular recognition motifs is described. We exploit the E?Z photoisomerization properties of azobenzenes to alter the shape of the cavity of the macrocycle upon absorption of light. Imidazolium motifs are used as hydrogen‐bonding donor components, allowing for sequestration of small molecule guests in acetonitrile. Upon E→Z photoisomerization of oAzoBox 4+ the guest is expelled from the macrocyclic cavity. 相似文献