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1.
Activated carbon production from almond shells using phosphoric acid activation agent was achieved by applying both conventional heating and microwave heating in succession. The morphology and surface properties of activated carbon were studied using thermogravimetric and differential gravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. A surface area of 1128 m2/g was achieved by optimizing the microwave power (500?W), microwave application time (15?minutes), conventional heating time (45?minutes), conventional heating temperature (500?°C), and the phosphoric acid:sample ratio (0.7:1). An adsorption capacity of methylene blue of 148?mg/g and an iodine value of 791?mg/g was obtained for the prepared activated carbon. 相似文献
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We extend the previously found accelerated Kerr-Schild metrics for Einstein-Maxwell-null dust and Einstein-Born-Infeld-null dust equations to the cases including the cosmological constant. This way we obtain the generalization of the charged de Sitter metrics in static space-times. We also give a generalization of the zero acceleration limit of our previous Einstein-Maxwell and Einstein-Born-Infeld solutions. 相似文献
6.
通过数值求解一维瞬态受激布里渊散射(SBS)声光耦合波方程,从理论上分析了泵浦激光参数及光学材料参数对SBS过程发生阈值的影响。以SBS过程中建立起来的应力场抗拉(压)强度和散射场的反射率为判据,分析了激光脉宽及作用区域长度对激光超声破坏材料效果的影响,探讨了短脉冲激光(约ns)引起的激光超声对材料的破坏机理;讨论了通过参数配置有效遏制SBS过程激光超声对光学材料的破坏问题。 相似文献
7.
We examine the nonlinear dynamical behavior of a spinor Bose-Einstein condensate in a double-well potential. Considering a condensate with large number of atoms, such that it can be described using the mean field theory, we separate the spinor dynamics from the spatial dynamics under the single-mode approximation. We limit ourselves to certain initial conditions under which the spatial mode is frozen so that we can focus on the spinor dynamics only. Identifying collective spin variables of our system, we derive the corresponding nonlinear equations of motion for them. Employing standard stability analysis, we find and characterize fixed points of the system. For a wide range of physical parameters such as tunneling strength and non-linear interactions, as well as for various initial preparations of the system, we identify qualitatively different dynamical regimes possible in the system. In particular, complete and incomplete oscillations of spin variables between quantum wells are found. We also show that by bringing some fixed points close to each other in the phase space of the system, it is possible to induce amplitude modulation to those otherwise regular tunneling oscillations. 相似文献
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The spectral structure of two parameter unbounded operator pencils of waveguide type is studied. Theorems on discreteness
of the spectrum for a fixed parameter are proved. Variational principles for real eigenvalues in some parts of the root zones
are established. In the case of n = 1 (quadratic pencils) domains containing the spectrum are described (see Fig. 1–3). Conditions in the definition of the
pencils of waveguide type arise naturally from physical problems and each of them has a physical meaning. In particular a
connection between the energetic stability condition and a perturbation problem for the coefficients is given. 相似文献
9.
分别用连续波1.319μm激光和10.6μm激光辐照PC型HgCdTe红外探测器时,得到了不同辐照光功率密度下,探测器输出的一系列实验结果。给出了在波长为1.319μm的波段内激光辐照下PC型HgCdTe探测器的饱和阈值;用波长为10.6μm的波段外CO2激光辐照探测器时,发现了一些与波段内激光辐照探测器时大不相同的实验现象;对实验结果进行了分析。简要总结了PC型HgCdTe探测器对于波段内和波段外激光辐照的响应机制。 相似文献
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The application of the recently introduced ethylchloroformate derivatization method for the separation and determination of selenomethionine and selenocystein in selenium-enriched yeast and yeast-free tablets by means of a gas chromatography-mass spectrometry (GC-MS) system has been studied. The efficiency of three methods for the extraction of selenomethionine from the tablets were compared. Total selenium content of the same tablets were measured using inductively coupled plasma (ICP)-MS and it was found that in the selenized yeast tablets about 80% of the total selenium is present as selenomethionine. The results were in agreement with the values in the labels and with the literature. The accuracy of the total selenium analysis was controlled by the analysis of a reference material. 相似文献