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131.
Ductile nickel-tungsten (Ni-W) alloys containing about 20–21 at.%W were electroplated onto copper substrates. The development
of the amorphous/nanocrystalline microstructure towards a complete crystallization by isochronal heat treatments in vacuum
was monitored by different methods. For medium annealing temperatures a solid-solution of W in the fcc-Ni lattice was achieved
resulting in an increased hardness. For temperatures of 600 °C and upward recrystallization started and thermodynamically
stable intermetallic compounds like Ni4W and NiW were formed. A third phase, containing more than 80 at.%W was also detected but could not be identified so far.
Only by combination of different methods and especially by use of analytical TEM structural analysis and phase identification
in these amorphous-nanocrystalline Ni-W alloys were successful. 相似文献
132.
Hardoko I. Qudus Purwadi Purwadi Iis Holilah Sutopo Hadi 《Molecules (Basel, Switzerland)》2021,26(11)
This research aimed at developing an analysis method, which was optimized and validated to determine the content of mercury in skin lightening cream discovered in the market in Bandar Lampung, Indonesia, through the use of microwave plasma atomic emission spectroscopy (MP-AES). The optimization on the analysis method was conducted on pump rate, viewing position, and reductant concentration in order to obtain the highest mercury emission intensity, while the solution stability was optimized to know the stability of mercury in the solution. The result showed that the method developed had precision with a relative standard deviation of 2.67%, recovery value of 92.78%, and linearity with an r value of 0.993, respectively. The sensitivity of the instrument detection had a limit of analysis method detection and quantification of 0.59 and 1.98 µg/L, respectively. The results of the test of the lightening cream (8 of 16 samples) positively contained mercury in the range of 422.61–44,960.79 ng/g. Therefore the method of analysis developed may be used for routine analysis of chemicals in any cosmetics products. 相似文献
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136.
唐雪平 《数学的实践与认识》2008,38(22)
讨论了一般二维井眼轨道设计问题.建立了二维轨道设计一般数学模型,根据轨道设计约束方程,可任意选择两个设计参数作为未知数进行求解,得到了全部解析计算公式.这种方法设计计算简单、精确、快速、灵活,具有普遍适用性.可广泛用于二维定向井、水平井和多目标井的设计,为井眼轨道设计提供了理论依据. 相似文献
137.
Xiangrong Xu Lee Koetzner Jamie Boulet Harry Maselli Jessica Beyenhof Gary Grover 《Biomedical chromatography : BMC》2009,23(9):973-979
A simple and sensitive analytical method using liquid chromatography–tandem mass spectrometry (LC/MS/MS) for determination of acetylsalicylic acid (aspirin, ASA) and its major metabolite, salicylic acid (SA), in animal plasma has been developed and validated. Both ASA and SA in plasma samples containing potassium fluoride were extracted using acetonitrile (protein precipitation) with 0.1% formic acid in it. 6‐Methoxysalicylic acid was used as the internal standard (IS). The compounds were separated on a reversed‐phase column. The multiple reaction monitoring mode was used with ion transitions of m/z 178.9 → 136.8, 137.0 → 93.0 and 167.0 → 123.0 for ASA, SA and IS, respectively. The lower limits of quantification for ASA and SA were 3 and 30 ng/mL, respectively. The developed method was successfully applied for the evaluation of pharmacokinetics of ASA and SA after p.o. and i.v. administration of 1 mg/kg to rats. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
138.
林一青 《数学的实践与认识》2008,38(6):136-142
对文艺复兴时写实绘画所采用的透视画法进行了精确的数学描述,并利用所得结论给出了使用计算机进行作图的方法. 相似文献
139.
V. N. Paimushin V. A. Ivanov S. A. Lukankin A. A. Bushkov A. E. Vyalkov 《Mechanics of Composite Materials》2005,41(1):23-32
Equations are set up for describing, in a correct statement and with an accuracy sufficient in actual practice, the shear buckling modes (BMs) of cylindrical sandwich shells with a transversely soft core of arbitrary thickness. Based on them, solutions are obtained to a number of problems on the buckling instability according to shear modes under some force and thermal loadings. It is found that the BMs occur in the shell along the circumferential and axial directions if, in the precritical state, a normal compressive stress arises in the transverse direction. It is shown that this condition is fulfilled in the following cases: in axial tension of the shell with unequal forces applied to the end faces of bearing layers (the parameter of critical load is maximum if the tensile forces are equal); under external (internal) pressure; on cooling the outer and heating the inner layers. The results obtained are presented in the form of simple analytical formulas for determining the corresponding critical parameters of the force and thermal actions.Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 1, pp. 37–48, January–February, 2005. 相似文献
140.
In this article, a novel semi-analytical algorithm for calculating backward-pumped Raman amplifier is proposed. The algorithm does not need iteration and can greatly save computational time. Simulation results for Raman amplifiers with 25 km, 50 km, and 100 km fibers show that the accuracy of the method is quite satisfying in comparison with the shooting algorithm and the deviation is within 0.02 dB. 相似文献