Mechanistic aspects of lean NO2 reduction by propane over HZSM-5

This study focuses on the mechanism of lean NO₂ reduction by propane. In particular the role of isocyanate- and amine species has been studied in transient experiments by in situ Fourier Transform Infrared (FTIR) spectroscopy. The results imply that these species are possible reaction intermediates over acidic HZSM-5.     

Quantitative Use of Paramagnetic Relaxation Enhancements for Determining Orientations and Insertion Depths of Peptides in Micelles

We describe the background and implementation of a method to determine, at atomic resolution, the insertion depths and orientations of peptides embedded in micelles. A nonperturbing paramagnetic agent—Gd(DTPA–BMA)—was used to induce paramagnetic relaxation enhancements (PREs) of peptide atoms inside the micelle. By calibrating these PREs it was possible to translate them into distance restraints that could be used for structure calculation. We demonstrate this here on the antimicrobial peptides novicidin and novispirin. Characterization of the interactions between antimicrobial peptides and membranes is important for understanding of their biological activities and functions, and a further development of tools to study these interactions is described.     

Dynamic Wettability of Different Machined Wood Surfaces

Wetting dynamics on machined wood surfaces is of great interest for the adhesive bonding technology of wood. In this work, the change of apparent contact angles with time of phenolresorcinol-formaldehyde (PRF), polyvinyl-acetate (PVAc), and a series of probe liquids on sawed, planed, sanded, and razor-blade-cut wood surfaces of Southern pine was studied by the sessile drop method using a CCD camera technique. The results indicate that the fastest wetting of the probe liquids occurs on the sanded surfaces because of higher surface roughness and the resulting increase in capillary forces as compared with the sawed, planed and razor blade cut surfaces. The fastest wetting of the PRF and PVAc resins occurred on the comparably smooth planed and razor-blade-cut wood surfaces. A smoother wood surface seems to provide better wetting and penetration properties for high-viscosity liquids such as adhesives, which probably can be attributed to less entrapment of air between the resin and the wood structure.     

Alternative method to precipitation techniques for synthesizing yttrium oxide nanopowder

Yttrium oxide nano-powder has been successfully synthesized by a novel approach. In the first step, a foamy structure was produced by combustion synthesis using yttrium nitrate and glycine. This was followed by the addition of sulfate ions and calcination at 1100 °C for 4 h. The sulfated and unsulfated powders were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller method (BET). The sinterability of the resulting powders was also studied by dilatometry. The studies indicated that this method not only allows for producing weakly-agglomerated nano-particles, but is also a very time-efficient process in comparison to precipitation techniques. Moreover, the possibility of performing all processing steps in a fully automated batch reactor was also considered.     

Analysis of pilots for residual frequency offset estimation in MIMO OFDM systems

This paper analyses the estimation of residual frequency offset in MIMO OFDM systems using pilot subcarriers embedded in the data payload. A closed-form expression for the MSE is derived and it shows how the frequency and spatial correlation influence performance. It is also shown that an orthogonal design ensures robust performance, which is independent of the frequency correlation of the channel.     

Electrochromic display cells driven by an electrolyte-gated organic field-effect transistor

Monolithic integration of an organic field-effect transistor (OFET) and an organic electrochromic display cell operating at around 1 V is reported. This was achieved by utilising a common patterned layer of poly(styrenesulfonic acid) (PSSH). In the OFET, PSSH served as the electric double layer capacitors between the gate and the organic semiconductor channel. In the electrochromic pixel, PSSH was included as the electrolyte and transports protons from and to the electrochromic layer upon switching. The enhancement mode OFET enables a relatively faster updating speed, of the display cell, and provides a much simpler addressing and updating scheme as compared to smart pixels including a depletion mode electrochemical transistor.     

Effect of composition and temperature on the burning velocity of the nitric oxide—hydrogen flame

The burning velocity of the nitric oxide-hydrogen flame has been measured at 1 atm, over the composition range 35–70% NO, for two initial temperatures, 298°K and 1023°K. In addition, the burning velocity of the 50% NO mixture was determined as a function of initial temperature over the temperature range 300 to 1000°K. A free radical mechanism is proposed in which the principal nitro-oxide destruction reaction is: H + NO = OH + N.     

用于千兆比特信号传输的高速、高密度夹层连接器

最新的通信技术不断提高数据传输速度要求。目前,PCB板上的数据信号速度已经达到了5Gbps并会在未来几年提升到10Gbps,因此需要增强的背板及夹层连接器技术来满足这些高速系统的信号完整性。背板连接器市场上目前已有的高速背板连接器如ERmet ZD连接器,其设计主要解决信号带宽、信号损失及电缆处理等方面的挑战。电信、数据通信市场的蓬勃发展是高速连接器,尤其是背板、板对板和I/O产品走向高速的推动因素。为了满足高速应用的需求,需要对接地、端子栅极及屏蔽的时候进行特别设计,其中最大的挑战是接地系统。高频接地可以通过连接器的接…     

Synthesis of monoglycerides by glycerolysis of rapeseed oil using immobilized lipase

Reaction conditions for the synthesis of monoglycerides (MG) by enzyme-catalyzed glycerolysis of rapeseed oil using Lipozyme® IM have been studied. Silica gel was used to adsorb the glycerol to overcome the problems of low glycerol solubility in the organic phase. An experimental design was used where temperature, time, the ratio of silica gel to glycerol (w/w), the water activity (a) _w , the isooctane concentration, and the ratio of glycerol to triglycerides (mol/mol) were varied. Response surface methodology was used to evaluate initial reaction rate and yield for the different products. The best yield of MG achieved under the studied conditions was 17.4% (mol fatty acid in substance/total mol fatty acid in mixture) (75°C, 20 h, silica gel/glycerol 2:1, a _w =0.17, 48% isooctane, glycerol/triglycerides 6:1). The same conditions yielded 36.8% diglycerides, 13.6% free fatty acids (FFA), and 36.9% triglycerides. This is at the same level as the equilibrium yield. The yield of MG is low compared to the final yield achieved with solid-phase glycerolysis. However, in solid-phase glycerolysis the reaction mixture becomes solid, and therefore the solid-phase process is not suitable for industrial application. The formation of FFA was very fast compared to the synthesis of MG. Equilibrium for FFA was reached within 2 h, and the yield was strongly affected by the a _w . Increasing a _w greatly increased the formation of FFA. In the a _w ratio 0.06–0.3, the yield of FFA increased from 4 to 19% while the yield of MG was nearly unaffected. As FFA is an undesired product, it is important to keep the a _w as low as possible.     

Enantioselective Organocatalytic Reactions of 4‐Hydroxycoumarin and 4‐Hydroxypyrone with α,β‐Unsaturated Aldehydes – An Efficient Michael Addition‐Acetalization Cascade to Chromenones,Quinolinones and Pyranones

An efficient, organocatalytic enantioselective addition‐cyclization reaction of cyclic 1,3‐dicarbonyl compounds with different α,β‐unsaturated aldehydes has been developed. The diarylprolinol ether‐catalyzed reaction cascade provides a variety of chromenones, quinolinones and pyranones in good yields and with excellent enantioselectivities.