Identification and Ruminal Outflow of Long-Chain Fatty Acid Biohydrogenation Intermediates in Cows Fed Diets Containing Fish Oil

The abundance of 20- to 24-carbon fatty acids in omasal digesta of cows fed grass silage-based diets supplemented with 0 (Control) and 250 g/day of fish oil (FO) was examined to investigate the fate of long-chain unsaturated fatty acids in the rumen. Complimentary argentation thin-layer chromatography and gas-chromatography mass-spectrometry analysis of fatty acid methyl esters and corresponding 4,4-dimethyloxazoline derivatives prepared from fish oil and omasal digesta enabled the structure of novel 20- to 22-carbon fatty acids to be elucidated. Compared with the Control, the FO treatment resulted in the formation and accumulation of 27 novel 20- and 22-carbon biohydrogenation intermediates containing at least one trans double bond and the appearance of cis-14 20:1, 20:2n-3, 21:4n-3 and 22:3n-6 not contained in fish oil. No conjugated ≥20-carbon fatty acids were detected in Control or FO digesta. In conclusion, fish oil in the diet results in the formation of numerous long-chain biohydrogenation intermediates in the rumen of lactating cows. Comparison of the intake and flow of 20-, 21- and 22-carbon fatty acids at the omasum in cows fed the Control and FO treatments suggests that the first committed steps of 20:5n-3, 21:5n-3 and 22:6n-3 hydrogenation in the rumen involve the reduction and/or isomerisation of double bonds closest to the carboxyl group.     

Application of Taguchi methods to DEM calibration of bonded agglomerates

Discrete element modelling (DEM) is commonly used for particle-scale modelling of granular or particulate materials. Creation of a DEM model requires the specification of a number of micro-structural parameters, including the particle contact stiffness and the interparticle friction. These parameters cannot easily be measured in the laboratory or directly related to measurable, physical material parameters. Therefore, a calibration process is typically used to select the values for use in simulations of physical systems. This paper proposes optimising the DEM calibration process by applying the Taguchi method to analyse the influence of the input parameters on the simulated response of powder agglomerates. The agglomerates were generated in both two and three dimensions by bonding disks and spheres together using parallel bonds. The mechanical response of each agglomerate was measured in a uniaxial compression test simulation where the particle was compressed quasi-statically between stiff, horizontal, frictionless platens. Using appropriate experimental designs revealed the most important parameters to consider for successful calibration of the 2D and 3D models. By analysing the interactive effects, it was also shown that the conventional calibration procedure using a “one at a time” analysis of the parameters is fundamentally erroneous. The predictive ability of this approach was confirmed with further simulations in both 2D and 3D. This demonstrates that a judicious strategy for application of Taguchi principles can provide a sound and effective calibration procedure.     

Evolution of the wettability between carbon fiber and epoxy as a function of temperature and resin curing

This article focuses on experimental studies on the wetting behavior between different carbon fibers (CFs) and epoxy as function of temperature, hardener addition, and progressive curing of the resin. The results indicate that surface sizing plays a key role in wettability of the CF with epoxy. There is a critical temperature for good‐wetting of DGEBA‐DDS mixture/CF. Complete wetting can be obtained for resin/CF after a period of curing time. Moreover, chemical reactions can not only improve the wettability but also strengthen interactions between the curing resin and CF. These results could provide an essential implication for understanding the formation process of interphase region of CF/epoxy composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Antimicrobial and anticoagulation activity of silver nanoparticles synthesized from the culture supernatant of Pseudomonas aeruginosa

Here, we describe biosynthesis of silver nanoparticles by reduction of aqueous Ag⁺ ions with the culture supernatant of Pseudomonas aeruginosa. The morphological, physiological, biochemical and molecular level identification of the strain GS1 resembles P. aeruginosa. The nanoparticles synthesized by P. aeruginosa were characterized by UV–vis spectroscopy, dynamic light scattering (DLS) and scanning electron microscopy (SEM). The size-distribution of nanoparticles was determined using a particle-size analyzer and the average particle-size was found to be 80 nm. The biological activities of the synthesized silver nanoparticles like antimicrobial activity were confirmed against Escherichia coli and Staphylococcus aureus and it have stable anti-coagulant effect.     

心电图用放大器的设计注意事项

心电图(ECG)设备的普及程度已显著加深,随着电子和机械设计的进步,如今的ECG已能够自主进行各种信号分析、提供实时显示,甚至使便携式设备能记录长时间的心电活动。这些高级功能依赖于心电信号的精确捕捉和调理,这使得放大器的选择和设计成为ECG系统成功的关键因素。此技术文章重点分析了心电图(ECG)用放大器的设计注意事项,其中包括信号调理、共模抑制、失调校正以及噪声消除等。     

Doping efficiency and energy-level scheme in C60F48-doped zinc–tetraphenylporphyrin films

High resolution synchrotron-based core level spectroscopy was used to examine the energy level alignment at the interface of zinc–tetraphenylporphyrin films doped by the surface acceptor C₆₀F₄₈. Two distinct fluorofullerene charge states were identified, corresponding to ionized and neutral molecules, and their relative concentration as a function of coverage was used to evaluate the probability of occupation of the acceptor lowest unoccupied molecular orbital (LUMO). From an initial acceptor energy of ?0.25 eV, the C₆₀F₄₈ LUMO shifts upwards with coverage due to a doping-induced interfacial dipole potential, and stabilization of the LUMO at an energy 0.45 eV above the Fermi energy was obtained. While the energy difference upon saturation is consistent with the results obtained for other donor–acceptor systems that have been interpreted as Fermi level pinning, the present work shows that the energy offset is a direct consequence of the interplay between Fermi–Dirac statistics in combination with the interfacial dipole potential.     

Continuous Synthesis of Device‐Grade Semiconducting Polymers in Droplet‐Based Microreactors

A method is reported for the controlled synthesis of device‐grade semiconducting polymers, utilizing a droplet‐based microfluidic reactor. Using poly(3‐hexylthiophene) (P3HT) as a test material, the reactor is shown to provide a controlled and stable environment for polymer synthesis, enabling control of molecular weight via tuning of flow conditions, reagent composition or temperature. Molecular weights of up to 92 000 Da are readily attainable, without leakage or reactor fouling. The method avoids the usual deterioration in materials quality that occurs when conventional batch syntheses are scaled from the sub‐gram level to higher quantities, with a prototype five‐channel reactor producing material of consistent molecular weight distribution and high regioregularity (>98%) at a rate of ≈60 g/day. The droplet‐synthesized P3HT compares favorably with commercial material in terms of absorption spectrum, polydispersity, regioregularity, and crystallinity, yielding power conversion efficiencies of up to 4% in bulk heterojunction solar cells with [6,6]‐phenyl‐C61‐butyric acid methyl ester.     

Intraphase Microstructure–Understanding the Impact on Organic Solar Cell Performance

A comprehensive study of the effect of intraphase microstructure on organic photovoltaic (OPV) device performance is undertaken. Utilizing a bilayer device architecture, a small molecule donor (TIPS‐DBC) is deposited by both spin‐coating and by thermal evaporation in vacuum. The devices are then completed by thermal evaporation of C₆₀, an exciton blocking layer and the cathode. This bilayer approach enables a direct comparison of device performance for donor layers in which the same material exhibits subtle differences in microstructure. The electrical performance is shown to differ considerably for the two devices. The bulk and interfacial properties of the donor layers are compared by examination with photoelectron spectroscopy in air (PESA), optical absorption spectroscopy, charge extraction of photo‐generated charge carriers by linearly increasing voltage (photo‐CELIV), time‐resolved photoluminescence measurements, X‐ray reflectometry (XR), and analysis of dark current behavior. The observed differences in device performance are shown to be influenced by changes to energy levels and charge transport properties resulting from differences in the microstructure of the donor layers. Importantly, this work demonstrates that in addition to the donor/acceptor microstructure, the intraphase microstructure can influence critical parameters and can therefore have a significant impact on OPV performance.     

Quasi‐One Dimensional in‐Plane Conductivity in Filamentary Films of PEDOT:PSS

The mechanism and magnitude of the in‐plane conductivity of poly(3,4‐ethy‐lenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films is determined using temperature dependent conductivity measurements for various PEDOT:PSS weight ratios with and without a high boiling solvent (HBS). Without the HBS the in‐plane conductivity of PEDOT:PSS is lower and for all studied weight ratios well described by the relation $ \sigma = \sigma _0 {\rm exp}[- \left({{{{T_0}}\over{T}}} \right)^{0.5}] $ with T₀ a characteristic temperature. The exponent 0.5 indicates quasi‐one dimensional (quasi‐1D) variable range hopping (VRH). The conductivity prefactor σ₀ varies over three orders of magnitudes and follows a power law σ₀∝c^3.5_PEDOT with c_PEDOT the weight fraction of PEDOT in PEDOT:PSS. The field dependent conductivity is consistent with quasi‐1D VRH. Combined, these observations suggest that conductance takes place via a percolating network of quasi‐1D filaments. Using transmission electron microscopy (TEM) filamentary structures are observed in vitrified dispersions and dried films. For PEDOT:PSS films with HBS, the conductivity also exhibits quasi‐1D VRH behavior when the temperature is less than 200 K. The low characteristic temperature T₀ indicates that HBS‐treated films are close to the critical regime between a metal and an insulator. In this case, the conductivity prefactor scales linearly with c_PEDOT, indicating the conduction is no longer limited by a percolation of filaments. The lack of observable changes in TEM upon processing with the HBS suggests that the changes in conductivity are due to a smaller spread in the conductivities of individual filaments, or a higher probability for neighboring filaments to be connected rather than being caused by major morphological modification of the material.