The determination of thermal properties of textile
materials is difficult and subject to errors. Here we used two experimental
methods. A PhotoPyroElectric method (Front PPE configuration with a
modulated heat flow imposed on the surface of the sensor) and a commercial
device (Alambeta) based the hot plate method. Two theorical approaches for
the latter device were used. We tested the two methods on different textile
materials (cotton, modal, wool and spacer). We observe good agreement
between thermal conductivities measured with the two methods. 相似文献
Liquid scintillation spectrometry is widely used for the analysis of alpha and beta emitting radionuclides. Robust calibration of liquid scintillation (LS) spectrometers is fundamental to accurate LS measurement but at the same time is time consuming and costly, particularly if a wide range of radionuclides are analysed by the laboratory. The frequency of the calibration varies in different laboratories and is based on many practical and operational factors. This work summarizes the observations regarding variations in 1220 Quantulus spectrometers efficiency calibrations performed annually using various radionuclides: 3H 63Ni, 55Fe, 36Cl, 45Ca, 147Pm, 241Pu, 99Tc for a period of 9 years and discusses the implication to calibration frequency.
The importance of β‐peptides lies in their ability to mimic the conformational behavior of α‐peptides, even with a much shorter chain length, and in their resistance to proteases. To investigate the effect of substitution of β‐peptides on their dominant fold, we have carried out a molecular‐dynamics (MD) simulation study of two tetrapeptides, Ac‐(2R,3S)‐β2,3hVal(αMe)‐(2S)‐β2hPhe‐(R)‐β3hLys‐(2R,3S)‐β2,3‐Ala(αMe)‐NH2, differing in the substitution at the Cα of Phe2 (pepF with F, and pepH with H). Three simulations, unrestrained (UNRES), using 3J‐coupling biasing with local elevation in combination with either instantaneous (INS) or time‐averaging (AVE) NOE distance restraining, were carried out for each peptide. In the unrestrained simulations, we find three (pepF) and two (pepH) NOE distance bound violations of maximally 0.22 nm that involve the terminal residues. The restrained simulations match both the NOE distance bounds and 3J‐values derived from experiment. The fluorinated peptide shows a slightly larger conformational variability than the non‐fluorinated one. 相似文献
Biofuels, such as bio‐ethanol, bio‐butanol, and biodiesel, are of increasing interest as alternatives to petroleum‐based transportation fuels because they offer the long‐term promise of fuel‐source regenerability and reduced climatic impact. Current discussions emphasize the processes to make such alternative fuels and fuel additives, the compatibility of these substances with current fuel‐delivery infrastructure and engine performance, and the competition between biofuel and food production. However, the combustion chemistry of the compounds that constitute typical biofuels, including alcohols, ethers, and esters, has not received similar public attention. Herein we highlight some characteristic aspects of the chemical pathways in the combustion of prototypical representatives of potential biofuels. The discussion focuses on the decomposition and oxidation mechanisms and the formation of undesired, harmful, or toxic emissions, with an emphasis on transportation fuels. New insights into the vastly diverse and complex chemical reaction networks of biofuel combustion are enabled by recent experimental investigations and complementary combustion modeling. Understanding key elements of this chemistry is an important step towards the intelligent selection of next‐generation alternative fuels. 相似文献
Mass spectrometry (MS) based proteomics has brought a radical approach to systems biology, offering a platform to study complex biological functions. However, key proteomic technical challenges remain, mainly the inability to characterise the complete proteome of a cell due to the thousands of diverse, complex proteins expressed at an extremely wide concentration range. Currently, high throughput and efficient techniques to unambiguously identify and quantify proteins on a proteome-wide scale are in demand. Miniaturised analytical systems placed upstream of MS help us to attain these goals. One time-consuming step in traditional techniques is the in-solution digestion of proteins (4-20 h). This also has other drawbacks, including enzyme autoproteolysis, low efficiency, and manual operation. Furthermore, the identification of α-helical membrane proteins has remained a challenge due to their high hydrophobicity and lack of trypsin cleavage targets in transmembrane helices. We demonstrate a new rapidly produced glass/PDMS micro Immobilised Enzyme Reactor (μIMER) with enzymes covalently immobilised onto polyacrylic acid plasma-modified surfaces for the purpose of rapidly (as low as 30 s) generating peptides suitable for MS analysis. This μIMER also allows, for the first time, rapid digestion of insoluble proteins. Membrane protein identification through this method was achieved after just 4 min digestion time, up to 9-fold faster than either dual-stage in-solution digestion approaches or other commonly used bacterial membrane proteomic workflows. 相似文献
We studied the influence of a pyridine moiety versus a phenyl moiety when introduced in the molecular design of an ambipolar host. These pyridine-based host materials for organic light-emitting diodes (OLEDs) were synthesized in three to five steps from commercially available starting materials. The isomeric hosts have similar HOMO/LUMO energies; however, data from OLEDs fabricated using the above host materials demonstrate that small structural modification of the host results in significant changes in its carrier-transporting characteristics. 相似文献