Morphological influence of graphitic carbon nanofibers by N–F dual-doping on Pt electrocatalytic activity and stability for oxygen reduction reaction in polymer electrolyte membrane fuel cells

Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N–F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs–NF–Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N–F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H–NF–Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H–NF–Pt as cathode catalyst with minimum loading of 0.10 mg cm^?2, delivers power density of 0.942 W cm^?2 at current density of 2.50 A cm^?2 without backpressures in H₂–O₂ feeds. The H–NF–Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell.     

Leucokinin and Associated Neuropeptides Regulate Multiple Aspects of Physiology and Behavior in Drosophila

Leucokinins (LKs) constitute a family of neuropeptides identified in numerous insects and many other invertebrates. LKs act on G-protein-coupled receptors that display only distant relations to other known receptors. In adult Drosophila, 26 neurons/neurosecretory cells of three main types express LK. The four brain interneurons are of two types, and these are implicated in several important functions in the fly’s behavior and physiology, including feeding, sleep–metabolism interactions, state-dependent memory formation, as well as modulation of gustatory sensitivity and nociception. The 22 neurosecretory cells (abdominal LK neurons, ABLKs) of the abdominal neuromeres co-express LK and a diuretic hormone (DH44), and together, these regulate water and ion homeostasis and associated stress as well as food intake. In Drosophila larvae, LK neurons modulate locomotion, escape responses and aspects of ecdysis behavior. A set of lateral neurosecretory cells, ALKs (anterior LK neurons), in the brain express LK in larvae, but inconsistently so in adults. These ALKs co-express three other neuropeptides and regulate water and ion homeostasis, feeding, and drinking, but the specific role of LK is not yet known. This review summarizes Drosophila data on embryonic lineages of LK neurons, functional roles of individual LK neuron types, interactions with other peptidergic systems, and orchestrating functions of LK.     

Cytotoxic Potential of a-Azepano- and 3-Amino-3,4-SeCo-Triterpenoids

Semi-synthetic triterpenoids, holding an amino substituted seven-membered A-ring (azepano-ring), which could be synthesized from triterpenic oximes through a Beckmann type rearrangement followed by a reduction of lactame fragment, are considered to be novel promising agents exhibiting anti-microbial, alpha-glucosidase, and butyrylcholinesterase inhibitory activities. In this study, in an attempt to develop new antitumor candidates, a series of A-ring azepano- and 3-amino-3,4-seco-derivatives of betulin, oleanolic, ursolic, and glycyrrhetinic acids were evaluated for their cytotoxic activity against five human cancer cell lines and non-malignant mouse fibroblasts by means of a colorimetric sulforhodamine assay. Azepanoallobetulinic acid amide derivative 11 was the most cytotoxic compound of this series but showed little selectivity between the different human tumor cell lines. Flow cytometry experiments showed compound 11 to act mainly by apoptosis (44.3%) and late apoptosis (21.4%). The compounds were further screened at the National Cancer Institute towards a panel of 60 cancer cell lines. It was found that compounds 3, 4, 7, 8, 9, 11, 15, 16, 19, and 20 showed growth inhibitory (GI₅₀) against the most sensitive cell lines at submicromolar concentrations (0.20–0.94 μM), and their cytotoxic activity (LC₅₀) was also high (1–6 μM). Derivatives 3, 8, 11, 15, and 16 demonstrated a certain selectivity profile at GI₅₀ level from 5.16 to 9.56 towards K-562, CCRF-CEM, HL-60(TB), and RPMI-8226 (Leukemia), HT29 (Colon cancer), and OVCAR-4 (Ovarian cancer) cell lines. Selectivity indexes of azepanoerythrodiol 3 at TGI level ranged from 5.93 (CNS cancer cell lines SF-539, SNB-19 and SNB-75) to 14.89 for HCT-116 (colon cancer) with SI 9.56 at GI₅₀ level for the leukemia cell line K-562. The present study highlighted the importance of A-azepano-ring in the triterpenic core for the development of novel antitumor agents, and a future aim to increase the selectivity profile will thus lie in the area of modifications of azepano-triterpenic acids at their carboxyl group.     

Novel energy-saving window coating based on F doped TiO2 nanocrystals with enhanced NIR shielding performance

To reduce the energy consumption of cooling in the hot summer days, searching for novel NIR shielding materials for buildings is of great value. In this report, monodispersed F doped TiO₂ nanocrystals with an average size of 8.6 nm were synthesized as novel solar shielding materials for energy-saving windows. All the products adopted an anatase TiO₂ structure. After doping of F ions, the morphology of TiO₂ was transformed from an irregular shape to a pseudospherical shape. The Raman shift and XPS depth analysis confirmed the successful doping of F⁻ ions into the lattice oxygen sites in the TiO₂ structure. The introduction of F⁻ ions generated free electrons and bulk Ti³⁺ in TiO₂ crystals, which activated a localized surface plasmon resonance (LSPR) absorption in the NIR region. Correspondingly, the NIR shielding performance of the TiO₂ films improved with increasing F doping amounts. The NIR shielding value of the films increased from 1.3% to 43.2% when the molar ratio of F to Ti increased from 0 to 0.3. The reason can be attributed to the enhanced NIR absorption induced by the increased electron concentration after doping of fluorine ions. The F–TiO₂ films showed superior visible transmittance (90.1–96.7%). Moreover, the F–TiO₂ films lowered the indoor temperature of the heat box by 5.3 °C in the thermal tests. Overall, the prepared F–TiO₂ nanocrystals show a great potential to be used for energy-saving windows.     

The alginate fermentation strain Pantoea sp. F16-PCAi-T3P21 and ethanol production

Bio-ethanol production from algae is a promising way to help solve the energy problem. Alginate is a major component of algae, but it cannot be utilized by existing ethanol fermentation microorganisms. In order to improve the utilization rate of brown algae, high alginate fermentation strains should be obtained. In this research, strains for algae fermentation were got from several experiments. The ethanol yield of strain A was the highest, which was 0.095 g/g (ethanol to alginate). The identification of strain A was carried out and it was 99% identical to Pantoea sp. F16-PCAi-T3P21. Fermentation experiments with different substrates were carried out, such as laminaran, mannitol, L. japonica and acid hydrolysate of L. japonica, and the ethanol yield rate of L. japonica acid hydrolysate was the highest, which reached 0.17 g/g ethanol to L. japonica. It showed that strain A can converse alginate to ethanol in a relatively high yield rate, and might be a promising strain with L. japonica as the substrate, we believe more research should be carried out on this strain.     

Hit to Leads with Cytotoxic Effect in Leukemic Cells: Total Synthesis Intermediates as a Molecule Treasure Chest

A previously designed and developed 12-step total synthesis that includes [1,1′-biphenyl]-2-amine and carbazole intermediates and that ultimately produces the carbazole alkaloid carbazomycin G was exploited as a screening compound library with the goal of identifying potential lead compound(s) with cytotoxic effect. These compounds were investigated by using in-vitro tests involving the two human cell lines HL-60 and MOLM-13, which both model acute myeloid leukaemia (AML). The in-vitro biological test results were used together with the molecular structures of the various intermediates in a concise SAR analysis. Several of the intermediates revealed cytotoxicity (IC₅₀<10⁻⁴ M), although the final natural product carbazomycin G did not reveal cytotoxicity versus the two said human cell lines.     

ZK60镁合金表面滚压强化试验研究

试验研究了ZK60镁合金表面滚压加工中工艺参数对试件表面粗糙度、表面形貌、表面残余应力和表层显微硬度的影响,结果表明滚压力和重复滚压次数对试件的表面粗糙度、表面形貌以及表面残余应力和表层硬度影响程度较大,滚压速度影响较小。对精车ZK60镁合金试件进行滚压加工,试件表面粗糙度R a、R z最大减小了50.3%和48.1%;残余压应力最大可达-54.55 MPa;显微硬度从试件表层到内部基体材料逐渐降低,表层硬度值最大为92.83 HV 0.25,比基体材料硬度提高了15.32%。     

云南野生黄毛草莓的营养价值评价和香气成分分析

分析黄毛草莓的果实品质和香气成分并对比其他栽培品种的差异，为其品质特性评价和香气利用奠定基础。通过直接滴定法、酸碱滴定法、福林酚法、直接法、2,6-二氯靛酚滴定法和质构仪测定法对4种草莓（黄毛草莓、密宝、哈尼、R7）的还原糖、总酸、总酚、花色苷、维生素C和硬度共6项指标进行测定，综合比较4种草莓的品质；运用顶空固相微萃取和气相色谱—质谱联用技术分析草莓果实的香气成分并做聚类分析。结果显示，在营养价值方面，黄毛草莓综合评分值仅次于哈尼排在第2位，高于密宝和R7。在果实香气方面，黄毛草莓的香气鉴定物质种类最多为83种，密宝有66种，哈尼有64种，R7有57种。在4种草莓的挥发物中，酯类是主要的挥发物（30.23%~52.70%），其中黄毛草莓的酯类相对含量最高（52.70%）。构成黄毛草莓特征香气的主要成分是香味酯：异戊酸乙酯、己酸乙酯、辛酸乙酯、乙酸辛酯、甲酸辛酯、癸酸乙酯、乙酸癸酯、香味醇反式-2-己烯-1-醇。黄毛草莓香气主成分聚类分析的结果显示，黄毛草莓和其他3个栽培品种分为两类，在香气主成分上与其他3种栽培品种存在显著差异。黄毛草莓中富含多种香精香料与洗护产品等行业所需的特殊香气成分，具有极大应用潜力。     

短波紫外线照射和~(60)Co-γ辐照处理对大樱桃贮藏品质的影响

为探究不同射线辐照处理对大樱桃果实保鲜效果的影响,采用不同剂量短波紫外线(short-wave ultraviolet light,UV-C)照射(1.37、2.05、2.74 kJ/m~2)和~(60)Co-γ辐照(0.75、1.5、2.25 kGy)分别处理大樱桃果实,定期检测其冷藏期间生理品质指标和果皮超微结构变化。结果表明:贮藏15 d内,1.37 kJ/m~2照射和0.75 kGy辐照较对照组可显著延缓大樱桃果实好果率下降、抑制果实质量损失,较好保持果实质地特性,促进花青素合成,有效抑制过氧化物酶与超氧化物歧化酶活性下降,但对可溶性固形物含量影响不大,且会引起丙二醛含量增加。由于两种处理对好果率、硬度、质量损失率、花青素等感官品质核心指标具有良好的积极作用,因此对丙二醛的不利变化并不足以影响到果实的商品品质评价。电子显微镜结果显示,大樱桃经1.37 kJ/m~2照射和0.75 kGy辐照处理后,与对照组相比,能在一定程度上减轻果皮细胞膜、线粒体、叶绿体等细胞结构的损伤程度,显著延缓果皮细胞衰老。此外,在贮藏前期与末期,1.37 kJ/m~2照射和0.75 kGy辐照所发挥的作用并不相同。针对于5 d以内的短期贮藏,可采用1.37 kJ/m~2 UV-C照射,而长期贮藏则以0.75 kGy~(60)Co-γ辐照效果更好。