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11.
Y. Isshiki J. Shi H. Nakai M. Hashimoto 《Applied Physics A: Materials Science & Processing》2000,70(4):395-402
Laser surface alloying (LSA) with silicon was conducted on austenitic stainless steel 304. Silicon slurry composed of silicon
particle of 5 μm in average diameter was made and a uniform layer was supplied on the substrate stainless steel. The surface
was melted with beam-oscillated carbon dioxide laser and then LSA layers of 0.4–1.2 mm in thickness were obtained. When an
impinged energy density was adjusted to be equal to or lower than 100 W mm−2, LSA layers retained rapidly solidified microstructure with dispersed cracks. In these samples, Fe3Si was detected and the concentration of Si in LSA layer was estimated to be 10.5 wt.% maximum. When the energy density was
equal to or greater than 147 W mm−2, cellular grained structure with no crack was formed. No iron silicate was observed and alpha iron content in LSA layers
increased. Si concentration within LSA layers was estimated to be 5 to 9 wt.% on average. Crack-free as-deposited samples
exhibited no distinct corrosion resistance. The segregation of Si was confirmed along the grain boundaries and inside the
grains. The microstructure of these samples changed with solution-annealing and the corrosion resistance was fairly improved
with the time period of solution-annealing.
Received: 2 September 1999 / Accepted: 6 September 1999 / Published online: 1 March 2000 相似文献
12.
Mario Thevis Andreas Thomas Maxie Kohler Simon Beuck Wilhelm Schänzer 《Journal of mass spectrometry : JMS》2009,44(4):442-460
The number of compounds and doping methods in sports is in a state of constant flux. In addition to ‘traditional’ doping agents, such as anabolic androgenic steroids or erythropoietin, new therapeutics and emerging drugs have considerable potential for misuse in elite sport. Such compounds are commonly based on new chemical structures, and the mechanisms underlying their modes of action represent new therapeutic approaches arising from recent advances in medical research; therefore, sports drug testing procedures need to be continuously modified and complementary methods developed, preferably based on mass spectrometry, to enable comprehensive doping controls. This tutorial not only discusses emerging drugs that can be categorized as anabolic agents (selective androgen receptor modulators, SARMs), gene doping [hypoxia‐inducible factor stabilizers, peroxisome‐proliferator‐activated receptor (PPAR)δ‐agonists] and erythropoietin‐mimetics (Hematide) but also compounds with potentially performance‐enhancing properties that are not classified in the current list of the World Anti‐Doping Agency. Compounds such as ryanodine‐calstabin‐complex modulators (benzothiazepines) are included, their mass spectrometric properties discussed, and current approaches in sports drug testing outlined. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
13.
A method for classifying orbits near asteroids 总被引:1,自引:0,他引:1
A method for classifying orbits near asteroids under a polyhedral gravitational field is presented, and may serve as a valuable reference for spacecraft orbit design for asteroid exploration. The orbital dynamics near aster- oids are very complex. According to the variation in orbit characteristics after being affected by gravitational perturbation during the periapsis passage, orbits near an as- teroid can be classified into 9 categories: (1) surrounding- to-surrounding, (2) surrounding-to-surface, (3) surrounding- to-infinity, (4) infinity-to-infinity, (5) infinity-to-surface, (6) infinity-to-surrounding, (7) surface-to-surface, (8) surface- to-surrounding, and (9) surface-to- infinity. Assume that the orbital elements are constant near the periapsis, the gravitation potential is expanded into a harmonic series. Then, the influence of the gravitational perturbation on the orbit is studied analytically. The styles of orbits are dependent on the argument of periapsis, the periapsis radius, and the periapsis velocity. Given the argument of periapsis, the orbital energy before and after perturbation can be derived according to the periapsis radius and the periapsis velocity. Simulations have been performed for orbits in the gravitational field of 216 Kleopatra. The numerical results are well consistent with analytic predictions. 相似文献
14.
Dionysios Raptis Charalampos Livas George Stavroglou Rafaela Maria Giappa Emmanuel Tylianakis Taxiarchis Stergiannakos George E. Froudakis 《Molecules (Basel, Switzerland)》2022,27(11)
The interaction strength of nitrogen dioxide (NO2) with a set of 43 functionalized benzene molecules was investigated by performing density functional theory (DFT) calculations. The functional groups under study were strategically selected as potential modifications of the organic linker of existing metal–organic frameworks (MOFs) in order to enhance their uptake of NO2 molecules. Among the functional groups considered, the highest interaction energy with NO2 (5.4 kcal/mol) was found for phenyl hydrogen sulfate (-OSO3H) at the RI-DSD-BLYP/def2-TZVPP level of theory—an interaction almost three times larger than the corresponding binding energy for non-functionalized benzene (2.0 kcal/mol). The groups with the strongest NO2 interactions (-OSO3H, -PO3H2, -OPO3H2) were selected for functionalizing the linker of IRMOF-8 and investigating the trend in their NO2 uptake capacities with grand canonical Monte Carlo (GCMC) simulations at ambient temperature for a wide pressure range. The predicted isotherms show a profound enhancement of the NO2 uptake with the introduction of the strongly-binding functional groups in the framework, rendering them promising modification candidates for improving the NO2 uptake performance not only in MOFs but also in various other porous materials. 相似文献
15.
This paper presents the dynamic characteristics of functionally graded beam with material graduation in axially or transversally through the thickness based on the power law. The present model is more effective for replacing the non-uniform geometrical beam with axially or transversally uniform geometrical graded beam. The system of equations of motion is derived by using the principle of virtual work under the assumptions of the Euler–Bernoulli beam theory. The finite element method is employed to discretize the model and obtain a numerical approximation of the motion equation. The model has been verified with the previously published works and found a good agreement with them. Numerical results are presented in both tabular and graphical forms to figure out the effects of different material distribution, slenderness ratios, and boundary conditions on the dynamic characteristics of the beam. The above mention effects play very important role on the dynamic behavior of the beam. 相似文献
16.
Experimental study on radiation effects in floating gate read-only-memories and static random access memories
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Radiation effects of the floating gate read-only-memory (FG ROM) and
the static random access memory (SRAM) have been evaluated using the
14~MeV neutron and 31.9MeV proton beams and Co-60 $\gamma $-rays. The
neutron fluence, when the first error occurs in the FG ROMs, is at
least 5 orders of magnitude higher than that in the SRAMs, and the
proton fluence, 4 orders of magnitude higher. The total dose
threshold for Co-60 $\gamma $-ray irradiation is about 10$^{4}$~rad
(Si) for both memories. The difference and similarity are attributed
to the structure of the memory cells and the mechanism of radiation
effects. It is concluded that the FG ROMs are more reliable as
semiconductor memories for storing data than the SRAMs, when they are
used in the satellites or space crafts exposed to high energy
particle radiation. 相似文献
17.
18.
By using the second-order moment of the power density, the beam width, far-field divergence angle and M2 factor of nonparaxial truncated flattened Gaussian (FG) beams are derived analytically. It is shown that the M2 factor of nonparaxial truncated FG beams depends not only on the truncation parameter δ and beam order N, but also on the initial waist-width to wavelength ratio w0/λ. The far-field divergence angle approaches an asymptotic value of θmax=63.435° when the truncation parameter δ → 0. For the special cases of N = 0 and δ → ∞ our results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated FG beams, respectively. 相似文献
19.
Ming‐Gang Li Jiang‐Yuan Zhao Shao‐Jie Gu Yuan Gao Fei Wang Jian‐Hai Ding Meng‐Liang Wen 《Helvetica chimica acta》2016,99(8):583-587
Eight phenylspirodrimane‐type analogues, including five new compounds, named stachartins A – E ( 1 , 3 , 6 – 8 ), were isolated from cultures of the tin mine tailings‐associated fungus Stachybotrys chartarum. Their structures were elucidated by spectroscopic methods including extensive 2D‐NMR techniques. 相似文献
20.
Ge Wang Wenhui Wu Quangang Zhu Shiqing Fu Xiaoyu Wang Shaotong Hong Ruihua Guo Bin Bao 《中国化学》2015,33(9):1089-1095
An isoindolone derivative, Fungi fibrinolytic compound (R)‐2,5‐bis((2R,3R)‐2‐((E)‐4,8‐dimethylnona‐3,7‐dien‐1‐yl)‐3,5‐dihydroxy‐2‐methyl‐7‐oxo‐3,4,7,9‐tetrahydropyrano[2,3‐e]isoindol‐8(2H)‐yl)pentanoic acid (FGFC1, Fungi fibrinolytic compound 1 ), was isolated from a rare marine microorganism strain Stachybotrys longispora FG216. The structure of FGFC1 was elucidated by 1H NMR, 13C NMR, IR, and MS data; moreover, it was also evaluated for fibrinolytic activity in vitro and in vivo. The results showed that 0.1–0.4 mmol/L of FGFC1 could stimulate generation of plasmin activity (increased by 2.05–11.44 folds) by measuring Glu‐plasminogen and Lys‐plasminogen activation in vitro. The experiment of fluorescein isothiocyanate (FITC)‐fibrinogen degradation indicated that the effect of FGFC1 on fibrinolytic activity was mediated by plasminogen and scuPA. In addition, FGFC1 (10 mg/kg) could dissolve most of pulmonary thrombus of Wistar rat in vivo. It is possible that FGFC1 is a potential thrombolytic agent in the future. 相似文献