Amino Acid Profiles of 44 Soybean Lines and ACE‐I Inhibitory Activities of Peptide Fractions from Selected Lines

Soybeans are cultivated in the United States chiefly for cooking oil, while the residue after oil extraction (soybean meal) is mostly used in animal feed formulations. High protein content in the defatted soybean meals led to the extraction of pure protein and its application in food products. We selected 44 soybean lines to determine their moisture and protein contents, and their amino acid composition was investigated. Soybean lines with high protein content, one high yielding (R95‐1705), and two high oleic acid (N98‐4445A, S03‐543CR), were selected for protein isolate preparation, hydrolysis using alcalase and gastro‐intestinal (GI) resistance. Furthermore, the GI resistant hydrolysates were fractionated and tested for angiotensin‐I‐converting enzyme (ACE‐I) inhibition activity. The amino acid analysis showed high methionine in the high protein and fatty acid lines (R05‐4494 and R05‐5491), and high cysteine content in one of the high oleic acid soybean line CRR05‐188 in comparison to the check lines (UA‐4805 and 5601‐T). The protein isolate with the highest purity (90–93 %) was derived from the selected lines N98‐4445A and S03‐543CR, and hydrolyzed using alcalase enzyme. The protein hydrolysates (500 µg/mL) showed inhibition of the ACE‐I by 49 %. The results from this study will promote the use of high oleic acid soybeans as a source of protein and peptides with functional activities.     

基于天然酯油的绿色变压器

2014年世界上首台使用天然酯绝缘油的420 k V电力变压器成功投入运行。这是420 k V电压等级电力设备中替代矿物油的重要一步和成功案例,在环境和健康保护方面具有重大意义。天然酯油的低燃点特性降低了在人口高密度地区使用变压器的潜在风险,也降低了在城市特别是大型城市中安装变压器在防火方面的费用。使用天然酯油的变压器对水资源无污染,这也使在高环保要求地区安装变压器成为可能。     

A Tripodal Peptidic Titanium Phosphonate as a Homochiral Porous Solid Medium for the Heterogeneous Enantioselective Hydration of Epoxides

A porous, homochiral titanium‐phosphonate material based on a tripodal peptide scaffold was used as a heterogeneous reaction medium for the enantioselective hydration (>99%) of styrene oxide. This titanium‐phosphonate material, which was shown to contain confined chiral spaces, was prepared by polymerization of L ‐leucine onto a tris(2‐aminoethyl)amine initiator, followed by capping with phosphonate groups and completed by non‐aqueous condensation with titanium isopropoxide. Circular dichroism confirmed that the peptide tethers yielded a secondary structure. X‐ray powder diffraction and transmission electron microscopy supported by a semi‐empirical model showed the likely formation of a porous, lamellar material that was quantified by nitrogen adsorption.     

Bis(trifluoromethyl)carbinol polynorbornene as a pseudo-polyelectrolyte in multilayered films

Using weak, opposed to strong polyelectrolytes in multilayer polymer systems provides a convenient means of altering some of the physico-chemical properties of these thin films. Recently, we pushed the limits of the weak polyacids by the introduction of an additional class of polyelectrolytes, the pseudo-polyelectrolytes (pPE). This paper focuses on another pPE, poly[5-(2-trifluoromethyl-1,1,1-trifluoro-2-hydroxypropyl)-2-norbornene] (PNBHFA). As, with poly(4-vinylphenol), multilayer assembly with both a weak and a strong polycation was accomplished from aqueous media. However, this was achieved only at a high pH value of 12.0. The films that were produced were exceptionally thick, > 1.25 μm after only 30 total layers for the poly(allylamine hydrochloride)/PNBHFA system. The films were very hydrophobic with the contact angle of water increasing with the layer number; reaching a maximum of ~ 123° after 50 total layers of poly(diallyldimethylammonium chloride)/PNBHFA.     

Aptasensing of chloramphenicol in the presence of its analogues: reaching the maximum residue limit

A novel, label-free folding induced aptamer-based electrochemical biosensor for the detection of chloramphenicol (CAP) in the presence of its analogues has been developed. CAP is a broad-spectrum antibiotic that has lost its favor due to its serious adverse toxic effects on human health. Aptamers are artificial nucleic acid ligands (ssDNA or RNA) able to specifically recognize a target such as CAP. In this article, the aptamers are fixed onto a gold electrode surface by a self-assembly approach. In the presence of CAP, the unfolded ssDNA on the electrode surface changes to a hairpin structure, bringing the target molecules close to the surface and triggering electron transfer. Detection limits were determined to be 1.6 × 10(-9) mol L(-1). In addition, thiamphenicol (TAP) and florfenicol (FF), antibiotics with a structure similar to CAP, did not influence the performance of the aptasensor, suggesting a good selectivity of the CAP-aptasensor. Its simplicity and low detection limit (because of the home-selected aptamers) suggest that the electrochemical aptasensor is suitable for practical use in the detection of CAP in milk samples.     

Factors of problem-solving competency in a virtual chemistry environment: The role of metacognitive knowledge about strategies

The ability to solve complex scientific problems is regarded as one of the key competencies in science education. Until now, research on problem solving focused on the relationship between analytical and complex problem solving, but rarely took into account the structure of problem-solving processes and metacognitive aspects. This paper, therefore, presents a theoretical framework, which describes the relationship between the components of problem solving and strategy knowledge.     

On the impact of post weld heat treatment on the microstructure and mechanical properties of creep resistant 2.25Cr–1Mo–0.25V weld metal

Creep resistant low-alloyed 2.25Cr-1Mo-0.25V steel is typically applied in hydrogen bearing heavy wall pressure vessels in the chemical and petrochemical industry. For this purpose, the steel is often joined via submerged-arc welding. In order to increase the reactors efficiency via higher operating temperatures and pressures, the industry demands for improved strength and toughness of the steel plates and weldments at elevated temperatures. This study investigates the influence of the post weld heat treatment (PWHT) on the microstructure and mechanical properties of 2.25Cr-1Mo-0.25V multi-layer weld metal aiming to describe the underlying microstructure-property relationships. Apart from tensile, Charpy impact and stress rupture testing, micro-hardness mappings were performed and changes in the dislocation structure as well as alterations of the MX carbonitrides were analysed by means of high resolution methods. A longer PWHT-time was found to decrease the stress rupture time of the weld metal and increase the impact energy at the same time. In addition, a longer duration of PWHT causes a reduction of strength and an increase of the weld metals ductility. Though the overall hardness of the weld metal is decreased with longer duration of PWHT, PWHT-times of more than 12 h lead to an enhanced temper resistance of the heat-affected zones (HAZs) in-between the weld beads of the multi-layer weld metal. This is linked to several influencing factors such as reaustenitization and stress relief in the course of multi-layer welding, a higher fraction of larger carbides and a smaller grain size in the HAZs within the multi-layer weld metal.

     

Rigorous electromagnetic analysis of dipole emission in periodically corrugated layers: the grating-assisted resonant-cavity light-emitting diode

We study the grating-assisted light-emitting diode, an LED design for high brightness based on a resonant cavity containing one- or two-dimensionally periodically corrugated layers (grating). We give in detail a generally applicable electromagnetic analysis based on the rigorous coupled-wave theory to calculate the extraction efficiency of spontaneous emission in a periodically corrugated layer structure. This general model is then specified on the grating-assisted resonant-cavity LED, showing simulated efficiencies of more than 40%.