Why do molecules echo atomic periodicity?

Franck–Condon factors are investigated for sequences of free main‐group diatomic molecules. Theory‐based Condon loci (parabolas) and Morse‐potential loci are plotted on Deslandres tables to verify if they, indeed, follow the largest Franck–Condon factors. Then, the inclination angles of the Condon loci are determined. Thus, entire band systems are quantified by one variable, the angle. For all available isoelectronic sequences, this angle increases from a central minimum toward magic‐number molecular boundaries. The theory for the Condon locus gives the angle in terms of the ratio of the upper‐state to the lower‐state force constants. It is concluded that the periodicity is caused due to the fact that this ratio becomes larger as rare‐gas molecules are approached, a trend that probably points to the extreme cases of the rare‐gas molecules themselves. Thus, molecular periodicity echoes atomic periodicity in that data plots have extrema at molecules with magic‐number atoms, yet it does not echo the details of atomic periodicity in series between those molecules. © 2013 The Authors. International Journal of Quantum Chemistry Published by Wiley Periodicals, Inc.     

Screening of Factors Influencing the Adsorption of Methylene Blue Aqueous Solution onto Raw Maize Cobs Using Fractional Factorial Design

Fractional factorial design is used to identify the significant variables that have large effects on the COD reduction and decolorization of methylene blue dye aqueous solution, through adsorption process. Four factors (pH, adsorbent dosage, temperature, and contact time) were screened by using the 2⁴ fractional factorial designs. The results showed that all the main factors have first-order interaction effects and second-order interaction effect, which were significantly affecting decolorization and COD reduction. Results obtained indicated that fractional factorial design can be used as a method to screen a large number of factors and to reduce the number of experimental runs.     

Molecular Lipophilicity Calculations of Chemically Heterogeneous Chemicals and Drugs on the Basis of Structural Similarity and Physicochemical Parameters

Abstract

QSARs based on molecular polarizability (α) and H-bond acceptor factors (∑C_a) as independent variables provided good predictability of octanol/water partition coefficients (P) for chemicals and drugs. However, for some molecules containing few functional groups, the calculated values deviated significantly from those observed. This approach gave good results when applied to a set of 138 chemicals and drugs previously studied by Mannhold and Dross who compared other methods to calculate log P values.

At the same time, three variations on a molecular similarity approach were pursued. In this study, a large training set with experimentally determined octanol/water partition coefficients (P) was searched for structures closely related to the compound-of-interest. The most successful of these variations took the mean log P value of few most closely related compounds after each was adjusted for differences between their and the compound-of-interest's polarizabilities (α) and H-bond acceptor capacities (∑C_a).     

The quality of QSAR models: problems and solutions†

Assessment of the quality of goodness-of-fit and the confidence in predictivity (prediction power) are the main terms used to define the statistical quality of QSAR models. Three parts of this assessment can be defined as:

(1)?Measure of goodness-of-fit.

(2)?Validation of model stability.

(3)?Predictivity analysis.

Currently there are no mandatory requirements for the validation methods to be used and rules for the quantitative confidence estimates. To compare the statistical quality of QSAR models it is necessary to have an overall statistical quality index which will depend on the goodness-of-fit, validation and predictivity results together. To do so it is necessary to define the set of mandatory parameters for all three parts of assessment listed above and develop the approach for overall quality estimates based on these parameters. It is also necessary to include into the overall index the penalty mechanism for parameter absence. The goal of the present study is to analyse parameters for all three parts of the QSAR model statistical quality assessment and investigate the flexible weighting approach for the overall statistical quality index development. Due the different statistical parameters traditionally used for assessment of goodness-of-fit it is necessary to create the mechanism, which allows flexible set of parameters to be used for the overall statistical quality index. Only after approval by scientific community and regulatory boards the final set of mandatory parameters can be selected.     

红外偏振成像系统的成像条件分析

红外偏振成像技术是未来目标搜索方法的研究热点,它对于入射角、目标表面粗糙度等条件比较敏感,为使红外偏振成像系统有效工作,有必要研究系统成像条件。研究从菲涅尔反射定理和基尔霍夫定律出发,分析了偏振产生原理;针对不同入射角、入射光强、观测波段、目标表面粗糙度、目标材质等观测因素对成像效果的影响,通过定性定量分析、数据仿真、对比实验得出结论。实验结果与之前的理论分析吻合,即当入射角越接近布儒斯特角时,反射光的线偏振程度越大,发现布儒斯特角并非红外偏振成像的最佳观测角;当光照强度越大,目标表面越光滑时,偏振度也越大。对于将偏振成像技术在目标搜索、跟瞄等领域的工程化应用有着重要的意义。     

TD-LTE系统中影响容量因素的研究

TD-LTE采用了OFDM、MIMO和AMC等先进技术,因此在容量规划方面表现得更加复杂。为更快地推动TD-LTE的技术研究与商用进程,当前亟需对TD-LTE容量规划技术进行研究。根据TD-LTE系统组网的工程实践,介绍了TD-LTE的容量特性和容量规划的基本原则,分析了影响TD-LTE容量特性的因素,包括资源分配、MIMO技术、同频组网和异频组网对容量的影响,提出了吞吐量计算以及容量分析的方法。研究结果为TD-LTE系统组网提供了参考依据。     

光学瞄具宽光谱透射率检测及误差影响因素分析

透射率参数是评价光学瞄具成像亮度和清晰程度的重要参数,介绍了一种高精度的光学瞄具宽光谱透射率的检测系统。针对检测过程中影响检测精度的因素包括偏振的敏感性、光束偏移、系统的杂散光、探测器的非线性和空间均匀性,结合验证实验和光学模拟软件(tracepro)给出定量的分析以及仪器的合成不确定度。对于探测器非线性误差利用最小二乘法原理予以修正。标定实验表明,可见光波段的透射率测量误差小于0.35%,近红外波段透射率测量误差小于0.65%。     

Flexible user-centric service selection algorithm for Internet of Things services

In Internet of Things (IoT), the similar functional services are evolving in different quality of services (QoS) due to the widespread deployment of spatially distributed things on dynamic networks through the web. Therefore, the user involvement in service selection systems becomes a vital role to enhance the system performance by taking into account of subjective factors. This paper proposes a flexible QoS-based service selection algorithm (FQSA) which mainly targets to the users to be able to give their subjective preferences in an easy and friendly manner. The FQSA algorithm selects the services based on subjective information provided by the service consumers and objective information supported by the service providers. It adopts artificial neural network backpropagation algorithm to find the objective factors and applies similarity aggregation method to evaluate the creditability of the user subjective factors which have already been evaluated by ontological reasoning with the help of proposed QoS ontology. The comparative study and experimental results show that our FQSA algorithm is superior to other service selection approaches.     

Natural Phenolic Acid,Product of the Honey Bee,for the Control of Oxidative Stress,Peritoneal Angiogenesis,and Tumor Growth in Mice

Tumor-associated macrophages (TAM) are key regulators of the link between inflammation and cancer, and the interplay between TAM and tumor cells represents a promising target of future therapeutic approaches. We investigated the effect of gallic acid (GA) and caffeic acid (CA) as strong antioxidant and anti-inflammatory agents on tumor growth, angiogenesis, macrophage polarization, and oxidative stress on the angiogenic model caused by the intraperitoneal (ip) inoculation of Ehrlich ascites tumor (EAT) cells (2.5 × 10⁶) in Swiss albino mouse. Treatment with GA or CA at a dose of 40 mg/kg and 80 mg/kg ip was started in exponential tumor growth phase on days 5, 7, 9, and 11. On day 13, the ascites volume and the total number and differential count of the cells present in the peritoneal cavity, the functional activity of macrophages, and the antioxidant and anti-angiogenic parameters were determined. The results show that phenolic acids inhibit the processes of angiogenesis and tumor growth, leading to the increased survival of EAT-bearing mice, through the protection of the tumoricidal efficacy of M1 macrophages and inhibition of proangiogenic factors, particularly VEGF, metalloproteinases -2 and -9, and cyclooxygenase-2 activity.     

我国化学教育类硕士的TPACK现状调查与分析

为在宏观上了解化学教育类硕士是否具有进行有效技术整合所必需的知识,基于TPACK提供的知识框架,对我国230名化学教育类硕士的TPACK水平及影响因素进行调查。结果表明,化学教育类硕士TPACK呈中等偏上水平;学术型硕士的TPACK水平高于专业型硕士;学习经历和实践经历对TPACK各要素有不同程度的影响;学习能力对TPACK的发展无显著影响;TPK、TCK和CK是影响TPACK发展的主要因素。在此基础上,提出了提升TPACK水平的相关策略。