The internal strain of three-dimensional braided composites with co-braided FBG sensors

The performance analysis of three-dimensional (3-D) braided composites is made difficult by their complex and interlacing structure, and is still under development. To get complete first-hand data on the material parameters of these composites, co-braided optical fiber sensors (OFS) can be used to measure the internal strain. This information is helpful for subsequent stiffness predictions and failure analysis. This paper introduces a method of incorporating OFS into braided composites, and establishes a constitutive theoretical model for the hybrid material. Experiments are conducted to measure the internal strain of specimens under tension, and the results are compared to theoretical predictions.     

The millimeter wave rotational spectrum of pyruvic acid

The rotational spectrum of pyruvic acid has been investigated for the first time in the millimeter-wave region, at 160-314 GHz, and also in supersonic expansion, at 10-17.4 GHz. The analysis of the broadband spectra recorded in this work was carried out with the newly developed AABS software package for Assignment and Analysis of Broadband Spectra, and precise spectroscopic constants are reported for the ground state, the first excited state of the low-frequency skeletal torsional mode ν₂₄, and the first excited state of the methyl torsional mode ν₂₃. Limited results have also been obtained for several higher excited states. The dataset for the ground state currently exceeds 1500 lines and for both the A and E internal rotor sublevels spans the complete range of values of K_a at the mid values of J for the measured transitions. The results were analysed with three freely available computer programs employing different strategies for dealing with internal rotation and a comparative discussion of their merits is made.     

Synthesis and applications of cyano‐vinylene‐based polymers containing cyclopentadithiophene and dithienosilole units for photovoltaic cells

Two β‐cyano‐thiophenevinylene‐based polymers containing cyclopentadithiophene ( CPDT‐CN ) and dithienosilole ( DTS‐CN ) units were synthesized via Stille coupling reaction with Pd(PPh₃)₄ as a catalyst. The effects of the bridged atoms (C and Si) and cyano‐vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about ?5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about ?3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron‐donor polymers ( CPDT‐CN and DTS‐CN ) blended with an electron‐acceptor, that is, [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) or [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM), in different weight ratios were explored under 100 mW/cm² of AM 1.5 white‐light illumination. The PSC device based on DTS‐CN: PC₇₁BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with V_oc = 0.74 V, J_sc = 8.39 mA/cm², and FF = 0.36. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Development of a highly α-selective galactopyranosyl donor based on a rational design

A galactosyl donor was rationally designed based on protecting group-stereoselectivity study. This donor was prepared and tested in a series of glycosylation reaction. Excellent α-selectivity was observed in the test reactions.     

一个参数自洽的超额函数模型

用热力学方法建立了一个新超额函数模型，它有3个模型参数。联立拟合H^E和G^E实验数据表明，对于非级性和弱极性液体混合物，这些参数值具有满意的自洽性。     

Synthesis,structure, and biological properties of a Co(II) complex with tridentate Schiff base ligand

A new Co(II) complex of general formula [Co(L)₂] has been synthesized from a NNO tridentate Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (L). The title complex is characterized by elemental, spectroscopic, antibacterial, and single crystal X-ray structural studies. X-Ray crystallography reveals that the complex shows a distorted octahedral geometry around the Co(II) ion. The complex was tested against several bacteria and shows good antibacterial activities against almost all of the bacteria. The interactions of the title complex with calf thymus deoxyribonucleic acid (CT-DNA) have been investigated by electronic absorption and fluorescence spectroscopy, showing that the complex interacts with CT-DNA via partial intercalation. Thermogravimetric analysis (TGA) of the complex has also been reported and the result shows that the complex is thermally stable up to 134 °C.     

An optimized gas chromatographic determination of priority pollutant phenols

Priority pollutant phenols are determined by gas chromatography on an SE-30 WCOT column using hydrogen carrier and flame ionization detection with dual internal standards. Linear responses over ranges ca. 12–125 ng per component are achieved and detection limits at or below 1 ng are obtained. Carrier flow and temperature program are optimized to maintain baseline resolution while affording an analysis time of less than 15 minutes.     

Ab initio study of long-range electron transfer between biphenyl anion radical and naphthalene

After the separation of the donor, the aeceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then the reorganization energy for the intermolecular electron transfer (ET) at the levels of HF/4-31G and HF/DZP is calculated. The ET matrix elements of the self-exchange reactions of the π-σ-π systems have been calculated by means of both the direct calculation based on the variational principle, and the transition energy between the molecular orbitals at the linear coordinate R=0.5. For the cross reactions, the ET matrix element and the geometry of the transition state are determined by searching the minimum energy splitting △_(min) along the reaction coordinate. In the evaluation of the solvent reorganization energy of the ET in solution, the Marcus' two-sphere model has been invoked. A few of ET rate constants for the intramolecular ET reactions for the π-σ-π systems, which contain     

EFFECT OF INTERNAL VISCOSITY OF POLYMERIC FLUIDS UNDER STRONG EXTENSIONAL FLOWS

The dumbbell model with internal viscosity for a dilute polymer solution is investigated based on a balance of viscous drag and restoring Brownian forces.An approximate method is used to obtain the solution of extensional stress in closed form in the case of steady flow.For different internal viscosities,this parametric study shows different asymptotic regimes of the extensional viscosity as a function of strain rate.This analysis may explain the attenuation of pressure drop in strong flows from a phenom...     

CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

Conformational elasticity theory recently developed has been used to explore the internal energy contribution tothe elastic force f_e/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1, 4-isoprene). Calculated f_e/f values arein good agreement with those obtained experimentally. Results show that behavior of f_e/f is mainly contributed by chemicalstructure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution isstrain dependent.