Unique Solubility of Switchable Alkyl-Amine Surfactants in Water

Because many amine surfactants are soluble in both water and CO₂ phases, they attract interest with regard to stabilizing CO₂-in-water dispersion systems. In our recent research, we find that the solubility of alkyl-amine surfactant in water can be significantly enhanced by salts, even though the salts are usually “salting-out” to other surfactants. The influence of various anions (NO₃⁻, Br⁻, Cl⁻, and SO₄²⁻) and cations (Na⁺, Ca²⁺, and Mg²⁺) on the alkyl-amine surfactants is investigated. The results are contrary to Hofmeister series and show that all the anions can enhance the solubility (salting-in) in the order of: NO₃⁻ > Br⁻ > Cl⁻ > SO₄²⁻, while the impact of the cations is insignificant. A physical–chemistry model based on the switchable property of the surfactant is proposed and well explains the experimental results. Therefore, the switchable alkyl-amine surfactants have potential to be applied under high-salinity and high-temperature conditions, for example, in enhanced oil recovery processes for a hot and salty carbonate reservoir.     

Synthesis of Aminotelechelic Prepolymers to Circumvent the Carbonation of Amines in Epoxy Coatings

This article deals with the amine blush phenomenon in epoxy coatings. Amine blush is due to amine carbonation and weakens the visual aspect of room temperature epoxy coatings. This paper describes a way to avoid the carbonation by preparing aminotelechelic prepolymers is described. For the first time, the amine‐adduct impact over amine carbonation, as well as the amine decarbonation with temperature, has been investigated by infrared spectroscopy. Moreover, a range of epoxy materials displaying various T_g are synthesized from amine‐adducts and compared to polyurethane references generally used for transparent coating applications. Mechanical and thermal properties are also investigated.

     

Lipid Dynamics in Diisobutylene-Maleic Acid (DIBMA) Lipid Particles in Presence of Sensory Rhodopsin II

Amphiphilic diisobutylene/maleic acid (DIBMA) copolymers extract lipid-encased membrane proteins from lipid bilayers in a detergent-free manner, yielding nanosized, discoidal DIBMA lipid particles (DIBMALPs). Depending on the DIBMA/lipid ratio, the size of DIBMALPs can be broadly varied which makes them suitable for the incorporation of proteins of different sizes. Here, we examine the influence of the DIBMALP sizes and the presence of protein on the dynamics of encased lipids. As shown by a set of biophysical methods, the stability of DIBMALPs remains unaffected at different DIBMA/lipid ratios. Coarse-grained molecular dynamics simulations confirm the formation of viable DIBMALPs with an overall size of up to 35 nm. Electron paramagnetic resonance spectroscopy of nitroxides located at the 5th, 12th or 16th carbon atom positions in phosphatidylcholine-based spin labels reveals that the dynamics of enclosed lipids are not altered by the DIBMALP size. The presence of the membrane protein sensory rhodopsin II from Natronomonas pharaonis (NpSRII) results in a slight increase in the lipid dynamics compared to empty DIBMALPs. The light-induced photocycle shows full functionality of DIBMALPs-embedded NpSRII and a significant effect of the protein-to-lipid ratio during preparation on the NpSRII dynamics. This study indicates a possible expansion of the applicability of the DIBMALP technology on studies of membrane protein–protein interaction and oligomerization in a constraining environment.     

Motuporamine Derivatives as Antimicrobial Agents and Antibiotic Enhancers against Resistant Gram‐Negative Bacteria

Dihydromotuporamine C and its derivatives were evaluated for their in vitro antimicrobial activities and antibiotic enhancement properties against Gram‐negative bacteria and clinical isolates. The mechanism of action of one of these derivatives, MOTU‐N44, was investigated against Enterobacter aerogenes by using fluorescent dyes to evaluate outer‐membrane depolarization and permeabilization. Its efficiency correlated with inhibition of dye transport, thus suggesting that these molecules inhibit drug transporters by de‐energization of the efflux pump rather than by direct interaction of the molecule with the pump. This suggests that depowering the efflux pump provides another strategy to address antibiotic resistance.     

Natural Rumen‐Derived trans Fatty Acids Are Associated with Metabolic Markers of Cardiac Health

Evidence suggests that industrial trans fatty acids (iTFA) impair lipid profiles while ruminant trans fatty acids (rTFA) may lower insulin resistance and blood pressure. The objective of this article was to determine if the plasma phospholipid percentage of rTFA is associated with a favorable cardiometabolic profile. We collected fasting blood samples from 200 individuals from Quebec city (QC, Canada) aged from 18 to 55 years old, including 100 obese (BMI ≥ 30 kg m^?2) and 100 non‐obese (BMI < 30 kg m^?2) men and women. Fatty acid levels in plasma phospholipids were determined using gas chromatography. After separating the subjects into two groups, according to the median percentage of rTFA in plasma phospholipids, participants in the group with higher percentages of rTFA (0.86 ± 0.24 %) had higher adiponectin levels (p = 0.01) and a lower blood pressure (systolic, p = 0.005; diastolic, p = 0.04). In contrast, concentrations in plasma phospholipids of elaidic acid, a major iTFA, are positively correlated with glycemia in non‐obese subjects (p = 0.01) and with both triacylglycerol (TAG) (p = 0.0007) and total cholesterol (TC) (p = 0.009) in obese subjects. These data suggest that rTFA may have beneficial effects on cardiometabolic risk factors conversely to their counterpart iTFA. Dietary sources of TFA should be taken into account in future cardiometabolic studies.     

涡轮增压器叶轮超速预过载处理技术的研究(2)——超速预过载叶轮最佳超速转速研究

利用弹性及弹塑性有限元法分析了某一尺寸的叶轮超速转速与塑性变形区面积及最大应力之间的关系 ,以及超速转速与超速预过载处理后内孔最大残余变形量之间的关系 ,判定出超速预过载处理后的叶轮在工作状态下的应力大小及分布情况。总结了叶轮最佳超速转速的确定方法 ,以确定经有限元分析的实际叶轮的最佳超速转速。现场应用表明 ,所采用的叶轮最佳超速转速的确定方法是正确的。     

A Computer Application Investigation on Modification of Nonpoisonous Fruit Packing Equipment

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Research on Bayesian Method of Direction Finding

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