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11.
Zainab Z. Ismail Basma B. Hameed 《The International journal of environmental studies》2013,70(2):122-138
Excess nitrogen is one of the main causes of eutrophication in water bodies. In this study, the undesirable agricultural lignocellulosic material giant reed was used to remove ammonium ions from aqueous solutions. Batch experiments were conducted to investigate the effect of various parameters such as contact time, initial ammonium concentration, adsorbent dosage, pH, particle size, agitation rate and phosphate coexisting during the ammonium adsorption process. The ammonium sorption capacity of fibrous giant reed (FGR) at equilibrium was 12.49?mg?N/g with a maximum removal efficiency of 76% observed within 30?min at pH range of 6.5–9.5. Results revealed that the Freundlich isotherm model fitted better with the sorption process than the Langmuir model, and the adsorption process was well described by pseudo-second-order kinetic model. FT-IR analyses indicated that complexation and ion exchange could be the main mechanisms for the ammonium removal by FGR. Results revealed that FGR has a sorption capacity comparable to that of other natural sorbents with the advantage of greater availability with no cost. 相似文献
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试验研究高顺式聚丁二烯复合橡胶VCR412在全钢巨型工程机械子午线轮胎胎侧胶中的应用。结果表明:配方中在相同的炭黑用量情况下与镍系顺丁橡胶相比高顺式聚丁二烯复合橡胶定伸更高,且具有较好综合物理性能及较低的压缩生热;在同等300%定伸VCR412配方炭黑减量相比镍系顺丁橡胶炭黑量不变情况下,综合物理性能更好且具有优异的抗屈挠裂口增长性能及更低压缩生热。 相似文献
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《Ceramics International》2019,45(12):14675-14683
In this work, the relationships between the composition-driven phase boundary, ferroelectricity and strain properties of the (1-x)(K0.48Na0.52)(Nb1-ySby)O3-xBi0.5(Na0.82K0.18)0.5ZrO3 (abbreviated as (1-x)KNN1-ySy-xBNKZ) ceramics were investigated. A giant electric field-induced strain of 0.3% (d331 = 750 p.m./V) and a low hysteresis (16.4%) were obtained in the 0.97KNN0.98S0.02-0.03BNKZ ceramics. The giant strain is attributed to the enhanced piezoelectricity induced by the appearance of the O-T phase boundary and the electric-field-induced phase transition from the relaxor phase to the ferroelectric phase. Furthermore, the 0.97KNN0.98S0.02-0.03BNKZ ceramics exhibit good thermal stability in the temperature range from 25 °C to 150 °C. Hence, this work can promote the practical applications of KNN-based lead-free piezoelectric ceramics in highly sensitive and precise piezoelectric actuators. 相似文献
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计及涡流效应和应力变化的超磁致伸缩换能器的动态模型 总被引:4,自引:3,他引:4
文中在Jiles—Atherton磁滞模型和换能器振动系统的结构动力学原理的基础上,考虑交流驱动时的涡流效应和应力状态的变化,建立了超磁致伸缩换能器的磁弹性动态模型。对换能器系统不同工作情况进行模型的仿真计算并与实验结果对比,发现模型与实验吻合较好。说明所建立的动态模型能较好地描述换能器系统输出应变与驱动磁场之间的关系。根据模型的计算结果拟合出了换能器系统的伯德图,用于指导对换能器系统进行频率跟踪控制。 相似文献
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The Giant panda communicates with conspecifics by depositing a mixture of volatile compounds (called scent marks) on trees and rocks. Using mass spectrometry, we identified 951 chemical components from scent glands, urine, vaginal secretions, and scent marks made by pandas. The scent marks of the two genders contained a similar array of chemicals but varied in concentration; specifically, males possessed a significantly greater amount of short chain fatty acids (F(1, 29) = 18.4, P = 0.002). Using stepwise discriminate analysis on the relative proportions of a subset of these chemicals, it was possible to classify gender (94% for males and females) and individuality (81% for males and 91% for females) from scent marks. The power to identify individual males was reduced due to the relatedness of two subjects. By cracking the identity code of Giant panda communication, we show insights into how these animals can match individuals with unique chemical profiles. Since radiocollaring is currently banned in China, the techniques described in this paper give field biologists a new means to identify and track pandas in the wild. 相似文献
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Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68 Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained. 相似文献