Multimode resonance bandpass filter with twin wideband channels

A bandpass filter with twin wideband channels in a single-layer guided-mode resonance grating is presented.Strong refractive-index modulation is used to support the excitation of multimode resonances TE1,0,TE1,1,TE2,0,TE1,2,and TE2,1,which are excited by the first and second diffraction orders,relate asymmetrical line shapes and broad low-transmission bands,where TE is the transverse electric.Taking advantage of narrow linewidth and sharp edge line shape in the spectra of TE2,υ(v is the mode),a bandpass filter with form factors of 0.61 and 0.7 for long-and short-wave channels is presented to demonstrate this concept.     

Existence and global attractivity of a positive periodic solution to a Lotka–Volterra model with mutual interference and Holling III type functional response

In this paper, a Volterra model with mutual interference and Holling III type functional response is investigated, some sufficient conditions which guarantee the existence and global attractivity of a positive periodic solution for the system are obtained and two examples are given to verify the results by using MatLab. Furthermore, our results improve the main results in the literature.     

氮化锗多形体的四方、单斜和正交畸变的理论研究

采用量子化学从头算方法,对Ge_3N_4的四方、单斜和正交结构同质异相体的微结构、态密度和声子谱进行了研究.形成焓为负值、弹性常数满足Born稳定性准则和声子谱无虚频等结果证实在0~20 GPa范围内3种相都能保持结构稳定.温度变化影响到晶胞体积,从而使体模量发生改变.3种Ge_3N_4都属于半导体,Ge原子和N原子之间存在明显的s-p杂化现象.当压强增大时诱发了离域电子,从而使体系的带隙减小.本文还采用准谐近似对Ge_3N_4的热力学性质进行了研究,结果表明,温度和压强对热膨胀系数、熵、热容、德拜温度和格林爱森参数产生了明显影响.m-Ge_3N_4和t-Ge_3N_4的热膨胀系数分别为o-Ge_3N_4的3倍和2倍.t-Ge_3N_4和o-Ge_3N_4的晶格谐振频率基本不受温度的影响.     

N-phosphoryl amino acid models for P–N bonds in prebiotic chemical evolution

Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.     

Electrochemical performance of 5 kW all-vanadium redox flow battery stack with a flow frame of multi-distribution channels

In this paper, a flow frame with multi-distribution channels is designed. The electrolyte flow distribution in the graphite felt electrode is simulated to be uniform at some degree with the tool of a commercial computational fluid dynamics (CFD) package of Star-CCM+. A 5 kW-class vanadium redox flow battery (VRB) stack composed of 40 single cells is assembled. The electrochemical performance of the VRB stack is investigated. Under the applied current density of 60 mA cm^?2 during the charge and discharge processes, the current and energy efficiencies are delivered to be 93.9 and 80.8 %, respectively. A higher average output power of 7.2 kW can be achieved at the current density of 80 mA cm^?2 with a lower energy efficiency of 78.4 %. The studies of kW-class VRB stack can be beneficial to the development of large-scale energy storage.