Cis Watson-Crick/Watson-Crick Base Pairs in DNA： A Density Functional Theory(DFT) Study

The four nucleic acid DNA bases（adenine, thymine, guanine, cytosine） and ten cis Watson-Crick/Watson-Crick（cis WC/WC） DNA base pairs were investigated by density functional theory（DFT） quantum chemical calculations. Geometry optimizations were carried out on the four bases and ten base pairs at the B3LYP level with 6-31G^（＊＊） basis set. All the optimizations were performed within Cs symmetry. The optimum structures for the four bases and seven cis WC/WC base pairs were obtained, and Natural Bond Orbital analysis（NBO） was based on these structures. The possibilities of matches between any two of the four bases through their Watson-Crick（WC） edges were discussed. The structures of seven cis WC/WC base pairs change to a certain extent relative to these of the four bases due to the formation of hydrogen bonds. These base pairs existing in DNA have an important influence on the structural stability of the double helix. The analysis of the electronic structures and molecular orbitals for seven cis WC/WC base pairs can provide significant information about the relationship between charge transfer along the hydrogen bond and the Frontier orbitals of these base pairs.

Electrodeposition and Characterization of CuInSe_2 Thin Films for Solar Cells

CulnSe2 （CIS） thin films were prepared by electrodeposition from the de-ionized water solution consisting of CuCl2, InCl3, H2SeO3 and Na-citrate onto Mo/soda-lime glass （SLG） substrates. A thermal processing in Se atmosphere at 450℃ was carried out for the electrodepositied films to improve the stoichiometry. The composition and morphology of selenized CIS thin films were studied using energy dispersive spectroscopy （EDS） and scanning electron microscopy （SEM）, respectively. X-ray diffraction （XRD） studies show that the annealing in Se atmosphere at 450℃ promotes the structural formation of CIS chalcopyrite structure.

Synthesis of the CuInSe_2 thin film for solar cells using the electrodeposition technique and Taguchi method

The Taguchi method was used to obtain the optimum electrodeposition parameters for the synthesis of the CuInSe2 thin film for solar cells. The parameters consist of annealing temperature, current density, CuCl2 concentration, FeCl3 concentration, H2SeO3 concentration, TEA amount, pH value, and deposition time. The experiments were carried out according to an L18（2^13^7） table An X-ray diffractometer （XRD） and a scanning electron microscope （SEM） were respectively used to analyze the phases and observe the microstructure and the grain size of the CuInSe2 film before and after annealing treatment. The results showed that the CuInSe2 phase was deposited with a preferred plane （112） parallel to the substrate surface. The optimum parameters are as follows： current density, 7 mA/cm^2; CuCl2 concentration, 10 mM; FeCl3 concentration, 50 mM; H2SeO3 concentration, 15 mM; TEA amount, 0 mL; pH value, 1.65; deposition time, 10 min; and annealing temperature, 500℃.

Collaborative information seeking: An investigation of community members' behavior

Purpose： This article reports on an experiment that tested community members＇ collaborative information seeking （CIS） behavior, with an emphasis on how community type and task difficulty can affect user behavior and user awareness in collaboration.Design/methodology/approach： We carried out a laboratory study with 18 participants in 9 pairs using an experimental CIS system. Data were collected from questionnaires, Web logs and semi-structured interviews. Descriptive statistics and two-way analysis of variance （ANOVA） were used for data analysis. Findings： Compared with non-community members, community participants had a better understanding of search tasks and were aware of the ways of completing tasks successfully. They did not depend on the information retrieval system when constructing search queries and would adopt diversified cooperation strategies. They were more likely to recommend information to their partners. However, no significant difference was found between subject- based community and interest-based community in CIS practices and user awareness in collaboration. In addition, task difficulty only influenced user preference of issuing queries and confidence of completing search tasks. Research limitations： Our work was limited by the community type we chose and the small group size, which could affect the generalizability of our findings and should be addressed in future studies. Practical implications： The study results will help inform information system designers as they design collaborative systems to facilitate social communication in the information seeking process. Originality/value： Few studies have investigated community participants＇ information seeking practices. This study provides insights into community-based CIS behavior. The findings will help us understand social interactions among community members during their information seeking process.

High-stage analog accumulator for TDI CMOS image sensors

The impact of the parasitic phenomenon on the performance of the analog accumulator in TDI CMOS image sensor is analyzed and resolved. A 128-stage optimized accumulator based on 0.18-μm one-poly four-metal 3.3 V CMOS technology is designed and simulated. A charge injection effect from the top plate sampling is em- ployed to compensate the un-eliminated parasitics based on the accumulator with a decoupling switch, and then a calibration circuit is designed to restrain the mismatch and Process, Voltage and Temperature （PVT） variations. The post layout simulation indicates that the improved SNR of the accumulator upgrades from 17.835 to 21.067 dB, while an ideal value is 21.072 dB. In addition, the linearity of the accumulator is 99.62%. The simulation results of two extreme cases and Monte Carlo show that the mismatch and PVT variations are restrained by the calibration circuit. Furthermore, it is promising to design a higher stage accumulator based on the proposed structure.