Phosphorylated chitosan/poly(vinyl alcohol) based proton exchange membranes modified with propylammonium nitrate ionic liquid and silica filler for fuel cell applications

In our previous work, phosphorylated chitosan was modified through polymer blending with poly(vinyl alcohol) (PVA) polymer to produce N-methylene phosphonic chitosan/poly(vinyl alcohol) (NMPC/PVA) composite membranes. The aim of this work is to further investigate the effects of a propylammonium nitrate (PAN) ionic liquid and/or silicon dioxide (SiO₂) filler on the morphology and physical properties of NMPC/PVA composite membranes. The temperature-dependent ionic conductivity of the composite membranes with various ionic liquid and filler compositions was studied by varying the loading of PAN ionic liquid and SiO₂-PAN filler in the range of 5–20 wt%. As the loading of PAN ionic liquid increased in the NMPC/PVA membrane matrix, the ionic conductivity value also increased with the highest value of 0.53 × 10^?3 S cm^?1 at 25 °C and increased to 1.54 × 10^?3 S cm^?1 at 100 °C with 20 wt% PAN. The NMPC/PVA-PAN (20 wt%) composite membrane also exhibited the highest water uptake and ion exchange capacity, with values of 60.5% and 0.60 mequiv g^?1, respectively. In addition, in the single-cell performance test, the NMPC/PVA-PAN (20 wt%) composite membrane displayed a maximum power density, which was increased by approximately 14% compared to the NMPC/PVA composite membrane with 5 wt% SiO₂-PAN. This work demonstrated that modified NMPC/PVA composite membranes with ionic liquid PAN and/or SiO₂ filler showed enhanced performance compared with unmodified NMPC/PVA composite membranes for proton exchange membrane fuel cells.     

Chemoenzymatic Asymmetric Synthesis of Pyridine-Based α-Fluorinated Secondary Alcohols

Fluoro-substituted and heteroaromatic compounds are valuable intermediates for a variety of applications in pharma- and agrochemistry and synthetic chemistry. This study investigates the chemoenzymatic preparation of chiral alcohols bearing a heteroaromatic ring with an increasing degree of fluorination in α-position. Starting from readily available picoline derivatives prochiral α-halogenated acyl moieties were introduced with excellent selectivity and 64–95 % yield. The formed carbonyl group was subsequently reduced to the corresponding alcohols using the alcohol dehydrogenase from Lactobacillus kefir, yielding an enantiomeric excess of 95–>99 % and up to 98 % yield.     

Collective reflection strategy for moderating conformity tendency and promoting reflective judgment performance

Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies.     

Structures and properties of chicken myofibrillar protein gel induced by microwave heating

Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics.     

HIGHER PLANT BIOMARKERS IN PALEOGENE CRUDE OILS FROM THE YUFUTSU OIL-AND GASFIELD AND OFFSHORE WILDCATS, JAPAN

Geochemical investigation of Paleogene oils from the onshore Yufutsu oil- and gasfield, southern Hokkaido, and from two nearby offshore wells, revealed the presence of numerous biomarkers of higher plant origin. Biomarkers in the oils belong to different groups of both angiosperm and gymnosperm origin; they include bicyclic sesquiterpanes, diterpanes, and triterpanes and their aromatized counterparts, which suggests a terrestrial origin for the oils. The oils were characterized as having a high wax content, a low content of organosulphur compounds, a high pristane/phytane ratio, and a low C₂₇/(C₂₇+C₂₉) sterane ratio.
Although the oils from on- and offshore Southern Hokkaido are similar in their geochemical composition, notable differences were observed in the biomarker signature of both saturate and aromatic fractions. The oils from the offshore wells appeared to have a greater abundance of higher plant biomarkers compared to those from the Yufutsu field, suggesting an enrichment in higher plant components. Differences in biomarker fingerprint could not be linked to the maturity effect, since the oils appeared to be of similar maturity levels, corresponding to the late stage of the oil window (0.9–1.2%, Rc). The differences in the biomarker signatures between the oils from the Yufutsu field and the offshore wells are likely to be due to facies variations in source organic matter, resulting from differences in the quantity and quality of land plant input.     

论激励教育

分析了高职学生的心理、惩罚教育的弊端,并从理论、心理、现实论述的基础上提出应大力提倡激励教育.     

阳离子型高温酸化缓蚀剂的合成及其性能评价

针对Mannich碱型缓蚀剂存在的溶解性不好和缓蚀率不高等问题,以甲醛、环己酮和苯胺为原料,合成了一种Mannich碱型缓蚀剂CH-9,将其阳离子化后,再与丙炔醇复配,得到了阳离子型高温酸化缓蚀剂CH-10。由室内性能评价可知,CH-10在盐酸中有良好的溶解分散性;与酸液中其他添加剂如粘土稳定剂和铁离子稳定剂的配伍性良好,不会对酸化地层造成堵塞;在90℃和常压下,在20%HCl溶液中加入浓度为1%的CH-10,其对N80钢片的腐蚀速率为4.765g/(m2·h);在120℃时,浓度为2%的CH-10对N80钢片的腐蚀速率为14.30g/(m2·h),均达到了SY/T5405-1996标准中的一级标准。     

SO4^2-／ZrO2固体超强酸的制备及其催化合成ETBE的研究

采用沉淀一浸渍法制备了负载型SO4^2-／ZrO2固体超强酸催化剂，运用IR、XRD等方法表征所制备催化剂的物化性质。结果表明，所制备的催化剂具有固体超强酸催化剂的特征，酸性与焙烧温度有关，适当提高焙烧温度有利于样品酸强度的提高，但焙烧温度过高会导致脱硫；浸渍液H2SO4浓度高有利于提高催化剂的硫含量，但是浓度过高，会在催化剂上形成硫酸盐，从而降低催化剂的比表面积和酸性。采用制备的催化剂气相催化乙醇与叔丁醇合成乙基叔丁基醚反应，乙基叔丁基醚的选择性为54．71％。