Transmission and filtering in photonic circuits: effects of absorption and amplification

We study the effect of absorption and amplification on transmission and filtering in one-dimensional dielectric photonic structures made of dangling side branches grafted periodically along an infinite monomode waveguide with defective branches. The loss and gain are introduced by adding an imaginary part ″ to the dielectric constant. We show that for reasonable values of ″, loss and gain affect essentially the transmission at the frequencies of localized modes associated with the defect branch introduced into the periodic structure. The amplitude and the phase of the transmission and reflection coefficients associated with defect modes are discussed as function of ″ and the size of the structure. The properties of the defect modes in presence of loss and gain can be used as an on/off switching device in a demultiplexer made of the above photonic structures.     

Graphical approach to analyzing DNA sequences

Recently, we proposed a 2D graphical representation of DNA sequence [J Comput Chem 25(2004) 1364-1368]. Based on this representation, we outline one approach to search optimal alignment. We also can judge the mutations between bases and an unknown sequence based on its graph and a known sequence's graph.     

脊髓小脑共济失调的分子遗传学研究进展

脊髓小脑共济失调（SCAs）是一组具有多变的小脑、脊髓小脑束和脑干神经元变性的异质性神经病．按照目前的分子分类法,SCAs包括SCA1～SCA27等亚型．SCAs同样具有遗传异质性,加上各亚型的临床症状有较多的重叠,使得临床亚型的确诊较为复杂．SCA1、SCA2、SCA3、SCA6、SCA7、SCA17和DRPLA由三核苷酸重复（CAG）n引起,SCA8和SCA10则分别由（CTG）n和（AT—TCT）n重复造成,而易感基因的点突变可能是SCA14和SCA27的分子病因．由于核苷酸重复的不稳定性,SCAs的一个主要特点是存在遗传早现．SCAs患者包含多聚谷氨酰胺的神经元核内及细胞质包涵体的作用不详,但其细胞内的蛋白质聚集现象可能是SCAs不同于其他异质性疾病的常见病理过程．     

Intermolecular Mechanism and Dynamic Investigation of Avian Influenza H7N9 Virus’ Susceptibility to E119V-Substituted Peramivir–Neuraminidase Complex

The H7N9 virus attaches itself to the human cell receptor protein containing the polysaccharide that terminates with sialic acid. The mutation of neuraminidase at residue E119 has been explored experimentally. However, there is no adequate information on the substitution with E119V in peramivir at the intermolecular level. Therefore, a good knowledge of the interatomic interactions is a prerequisite in understanding its transmission mode and subsequent effective inhibitions of the sialic acid receptor cleavage by neuraminidase. Herein, we investigated the mechanism and dynamism on the susceptibility of the E119V mutation on the peramivir–neuraminidase complex relative to the wildtype complex at the intermolecular level. This study aims to investigate the impact of the 119V substitution on the neuraminidase–peramivir complex and unveil the residues responsible for the complex conformations. We employed molecular dynamic (MD) simulations and extensive post-MD analyses in the study. These extensive computational investigations were carried out on the wildtype and the E119V mutant complex of the protein for holistic insights in unveiling the effects of this mutation on the binding affinity and the conformational terrain of peramivir–neuraminidase E119V mutation. The calculated total binding energy (ΔG_bind) for the peramivir wildtype is −49.09 ± 0.13 kcal/mol, while the E119V mutant is −58.55 ± 0.15 kcal/mol. The increase in binding energy (9.46 kcal/mol) is consistent with other post-MD analyses results, confirming that E119V substitution confers a higher degree of stability on the protein complex. This study promises to proffer contributory insight and additional knowledge that would enhance future drug designs and help in the fight targeted at controlling the avian influenza H7N9 virus. Therefore, we suggest that experimentalists collaborate with computational chemists for all investigations of this topic, as we have done in our previous studies.     

Structural Investigations and Binding Mechanisms of Oseltamivir Drug Resistance Conferred by the E119V Mutation in Influenza H7N9 Virus

The use of vaccinations and antiviral medications have gained popularity in the therapeutic management of avian influenza H7N9 virus lately. Antiviral medicines are more popular due to being readily available. The presence of the neuraminidase protein in the avian influenza H7N9 virus and its critical role in the cleavage of sialic acid have made it a target drug in the development of influenza virus drugs. Generally, the neuraminidase proteins have common conserved amino acid residues and any mutation that occurs around or within these conserved residues affects the susceptibility and replicability of the influenza H7N9 virus. Herein, we investigated the interatomic and intermolecular dynamic impacts of the experimentally reported E119V mutation on the oseltamivir resistance of the influenza H7N9 virus. We extensively employed molecular dynamic (MD) simulations and subsequent post-MD analyses to investigate the binding mechanisms of oseltamivir-neuraminidase wildtype and E119V mutant complexes. The results revealed that the oseltamivir-wildtype complex was more thermodynamically stable than the oseltamivir-E119V mutant complex. Oseltamivir exhibited a greater binding affinity for wildtype (−15.46 ± 0.23 kcal/mol) relative to the E119V mutant (−11.72 ± 0.21 kcal/mol). The decrease in binding affinity (−3.74 kcal/mol) was consistent with RMSD, RMSF, SASA, PCA, and hydrogen bonding profiles, confirming that the E119V mutation conferred lower conformational stability and weaker protein–ligand interactions. The findings of this oseltamivir-E119V mutation may further assist in the design of compounds to overcome E119V mutation in the treatment of influenza H7N9 virus patients.     

采用纳米金和双链探针比色检测单碱基突变

将链置换的高度特异性与纳米金凝聚变色的光学特性相结合,设计了一种新型的单碱基突变比色检测方法。本方法直接采用纳米金作为比色报告基团,以两个末端均带有巯基的双链DNA为特异捕获探针,利用互补序列和单碱基突变序列对双链探针置换能力的差异,实现了对单碱基突变的检测。本检测方法直观、快速、简便、成本低,pmol级的样品无需仪器就可以观察到颜色的变化。     

Mass and isotopic concentrations of water-insoluble refractory carbon in total suspended particulates at Mt. Waliguan Observatory (China)

Mass concentration and isotopic values δ¹³C and ¹⁴C are presented for the water-insoluble refractory carbon (WIRC) component of total suspended particulates (TSP), collected weekly during 2003, as well as from October 2005 to May 2006 at the WMO-GAW Mt. Waliguan (WLG) site. The overall average WIRC mass concentration was (1183 ± 120) ng/m³ (n = 79), while seasonal averages were 2081 ± 1707 (spring), 454 ± 205 (summer), 650 ± 411 (autumn), and 1019 ± 703 (winter) ng/m³. Seasonal variations in WIRC mass concentrations were consistent with black carbon measurements from an aethalometer, although WIRC concentrations were typically higher, especially in winter and spring. The δ¹³C PDB value (−25.3 ± 0.8)‰ determined for WIRC suggests that its sources are C₃ biomass or fossil fuel combustion. No seasonal change in δ¹³C PDB was evident. The average percent Modern Carbon (pMC) for ¹⁴C in WIRC for winter and spring was (67.2 ± 7.7)% (n = 29). Lower pMC values were associated with air masses transported from the area east of WLG, while higher pMC values were associated with air masses from the Tibetan Plateau, southwest of WLG. Elevated pMC values with abnormally high mass concentrations of TSP and WIRC were measured during a dust storm event.     

Electrochemical Detection of DNA Hybridization Based on the Probe Labeled with Carbon‐Nanotubes Loaded with Silver Nanoparticles

A sensitive electrochemical method for the detection of DNA hybridization based on the probe labeled with multiwall carbon‐nanotubes (MWNTs) loaded with silver nanoparticles (Ag‐MWNTs) has been developed. MWNTs were electroless‐plated with a large number of silver nanoparticles to form Ag‐MWNTs. Probe single strand DNA (ss‐DNA) with a thiol group at the 3′‐terminal labeled with Ag‐MWNTs by self‐assembled monolayer (SAM) technique was employed as an electrochemical probe. Target ss‐DNA with a thiol group was immobilized on a gold electrode by SAM technique and then hybridized with the electrochemical probe. Binding events were monitored by differential pulse voltammetric (DPV) signal of silver nanoparticles. The signal difference permitted to distinguish the match of two perfectly complementary DNA strands from the near perfect match where just three base pairs were mismatched. There was a linear relation between the peak current at +120 mV (vs. SCE) and complementary target ss‐DNA concentration over the range from 3.1×10^?14 to 1.0×10^?11 mol/L with a detection limit of 10 fmol/L of complementary target ss‐DNA. The proposed method has been successfully applied to detection of the DNA sequence related to cystic fibrosis. This work demonstrated that the MWNTs loaded with silver nanoparticles offers a great promising approach for sensitive detection of DNA hybridization.     

激光技术在林木和园艺植物育种及基因工程中的应用

激光具有极高的功率密度，因而可被应用于种子催芽和诱变育种，可作为林木和园艺植物育种和基因改良的新技术手段。文章从四个方面进行了探讨：（1）激光辐照的生物效应机理；（2）激光在林木和园艺植物种子催芽中的应用；（3）激光在林木和园艺植物诱变育种中的应用；（4）激光在林木和园艺植物基因工程中的应用。     

Speeding up chaos and limit cycles in evolutionary language and learning processes

Evolution of human language and learning processes have their foundation built on grammar that sets rules for construction of sentences and words. These forms of replicator–mutator (game dynamical with learning) dynamics remain however complex and sometime unpredictable because they involve children with some predispositions. In this paper, a system modeling evolutionary language and learning dynamics is investigated using the Crank–Nicholson numerical method together with the new differentiation with non‐singular kernel. Stability and convergence are comprehensively proven for the system. In order to seize the effects of the non‐singular kernel, an application to game dynamical with learning dynamics for a population with five languages is given together with numerical simulations. It happens that such dynamics, as functions of the learning accuracy μ, can exhibit unusual bifurcations and limit cycles followed by chaotic behaviors. This points out the existence of fickle and unpredictable variations of languages as time goes on, certainly due to the presence of learning errors. More interestingly, this chaos is shown to be dependent on the order of the non‐singular kernel derivative and speeds up as this derivative order decreases. Hence, can people use that order to control chaotic behaviors observed in game dynamical systems with learning! Copyright © 2016 John Wiley & Sons, Ltd.