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Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters

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science China Chemistry 2024年第11期67卷 3791-3797页

作者： Debasis Pal Kirana D.Veeranna Yuk Fai Wong P.Andrew evans Department of Chemistry Queen's University Xiangya school of Pharmaceutical sciences Central South University

The Reformatsky reagent derived from ethyl bromoacetate circumvents the challenge associated with the direct regio-and enantioselective iridium-catalyzed allylic alkylation with an unstabilized aliphatic ester enolate. Notably, this work represents the first example of using a Reformatsky reagent in a metal-allyl reaction, which permits the direct construction of enantioenriched β-stereogenic homoallylic esters without preactivation of the pronucleophile or post-reaction modification of the product(e.g., thermal decarboxylation of a 1,3-dicarbonyl). Moreover, the process allows the coupling of a broad range of sterically and electronically diverse electrophiles bearing aryl, heteroaryl and alkenyl derivatives, including the significantly more challenging alkyl-substituted allylic carbonates. The versatility of the ester product is exemplified by a series of functional group manipulations and the development of a concise and efficient enantioselective total synthesis of the natural product,(+)-descurainolide A. Finally, mechanistic studies indicate that the zinc enolate behaves as a soft nucleophile that undergoes outer-sphere alkylation.

关键词： allylic substitution asymmetric catalysis mechanistic studies natural product synthesis Reformatsky reagent

数字化能源管理系统促进工业界节能减碳的分析与建议

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中国科学院院刊 2024年第2期39卷 311-322页

作者：耿端阳许通朱庆华 s.eve evans 英国剑桥大学工程系制造研究所剑桥CB30FS 英国剑桥大学土地经济系环境能源与自然资源管理中心剑桥CB33QZ 上海交通大学安泰经济与管理学院上海200030

工业生产是碳排放的主要来源。减少能源浪费、达成生产节能对实现我国“双碳”目标至关重要。随着数字化技术进步,数字化能源管理系统可通过将不可见的能源可视化,促进企业节能。文章分析了英国、美国、德国、日本和瑞典应用能源管理系... 详细信息

工业生产是碳排放的主要来源。减少能源浪费、达成生产节能对实现我国“双碳”目标至关重要。随着数字化技术进步,数字化能源管理系统可通过将不可见的能源可视化,促进企业节能。文章分析了英国、美国、德国、日本和瑞典应用能源管理系统的现状,总结了其特点与应用条件,与我国在此方面的发展进行了对比,并探讨了我国在部署能源管理系统过程中所面临的挑战。文章还提出从“工厂、产线和设备”到“产品”角度分析能耗,构建“基于生产步骤的单位产品能耗标签”的方法论框架。探讨了政府、企业等利益相关者在该方法论中的角色,并提出了政府支持发展数字化能源管理系统的对策,包括推动系统建设、支持合作、确定能耗基准和引导企业对标行业最优实践。

关键词：数字化技术能源浪费能源管理能源系统碳中和

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Giving Food a Fiber Boost: Adding High Beta-Glucan Ingredient from Barley to everyday Foods

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Food and Nutrition sciences 2024年第4期15卷 277-289页

作者： Gongshe Hu sherry Ellberg Kathy satterfield Chris evans UsDA ARS Pacific West Area 1691 S. 2700 W Aberdeen Idaho USA

Lack of dietary fiber contributes to many health issues, particularly chronic vascular diseases. Mixed linkage β-1.3 - 1.4 beta-glucan (beta-glucan, in this paper) is a confirmed beneficial ingredient for the human diet through reduction of cholesterol and the glycemic index. Barley contains the highest beta-glucan content of all the grains, and in this study, a percentage of flour from two high beta glucan lines was, each, added to an array of wheat-based food products to measure how it impacted total dietary fiber. Results showed that beta-glucan content was higher in all the products containing the added high beta-glucan flour, along with increased total dietary fiber content. Protein content in the food products is also increased with the higher protein in the barley flours added. Beta-glucan content in the barley-added products increased to 1.2% - 4.0% versus 0.2% - 0.5% in the pure wheat products, while the dietary fibers increased to 3.5% - 24.4% versus 2.1% - 9.1% in pure wheat product controls. This research provided experimental evidence that using a high beta-glucan barley ingredient in food can increase dietary fiber to benefit health.

关键词： Food High Fiber Barley Ingredient Beta-Glucan Human Health

Isolative synthesis and Characterization of Cellulose and Cellulose Nanocrystals from Typha angustifolia

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Open Journal of Applied sciences 2024年第9期14卷 2443-2459页

作者： Lynda s. Mesoppirr evans K. suter Wesley N. Omwoyo Nathan M. Oyaro simphiwe M. Nelana Department of Mathematics and Physical science Maasai Mara University Narok Kenya Biotechnology and Chemistry Department Vaal University of Technology Vanderbijlpark South Africa

The application potential of cellulosic materials in natural composites and other fields needs to be explored to develop innovative, sustainable, lightweight, functional biomass materials that are also environmentally friendly. This study investigated Typha angustifolia (Typha sp.) as a potential new raw material for extracting cellulose nanocrystals (CNCs) for application in wastewater treatment composites. Alkaline treatments and bleaching were used to remove cellulose from the stem fibres. The CNCs were then isolated from the recovered cellulose using acid hydrolysis. The study showed a few distinct functional groups (O-H, -C-H, =C-H and C-O, and C-O-C) in the Fourier Transform Infrared (FTIR) spectra. A scanning electron microscope (sEM) revealed the smooth surface of CPC and CNCs, which resulted from removing lignin and hemicellulose from powdered Typha angustifolia. Based on the crystalline index, the powdered Typha angustifolia, CPC, and CNCs were 42.86%, 66.94% and 77.41%. The loss of the amorphous section of the Typha sp. fibre resulted in a decrease in particle size. It may be inferred from the features of a Typha sp. CNC that CNCs may be employed as reinforcement in composites for wastewater treatment.

关键词： Typha angustifolia Cellulose Acid Hydrolysis Chemically Purified Cellulose Cellulose Nanocrystals

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从不准时:变体与事后性

中世纪与文艺复兴研究 2024年第1期 83-98页

作者：露斯·埃文斯圣路易斯大学英语系

本文重新解读了中古英语文学作品中手稿变体对句法和意义产生的效果。论文借用“事后性”(弗洛伊德称之为“延迟性”)这一心理分析概念,以《巴斯妇人的开场语》为个案,将变体视为一个双向时间结构。伯纳德·塞尔奎利尼在《对变体的赞美... 详细信息

本文重新解读了中古英语文学作品中手稿变体对句法和意义产生的效果。论文借用“事后性”(弗洛伊德称之为“延迟性”)这一心理分析概念,以《巴斯妇人的开场语》为个案,将变体视为一个双向时间结构。伯纳德·塞尔奎利尼在《对变体的赞美》(1989)中将变体描述为一种产生新句法结构的活动。异文追溯、重构了它嵌入其中的话语的句法。异文不是嵌入固定句法结构的替代词汇选择;它们应被视为动态组合,当它们在话语中出现时,会改变每个话语的结构,往前往后都起作用。因此,意义永远不会准时到达,而是总会延迟。

关键词：变体事后性双向性手稿研究中古英语乔叟《巴斯妇人的开场语》誊稿人亚当

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The importance of pre-and postcopulatory sexual selection promoting adaptation to increasing temperatures

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Current Zoology 2021年第3期67卷 321-327页

作者： Miguel Gomez-Llano eve scott Erik I.svensson Department of Biological sciences University of ArkansasFayettevilleAR72701USA Faculty of Biology Medicine and HealthThe University of ManchesterOxford RoadManchesterM139PLUK Department of Animal and Plant sciences The University of SheffieldSheffieldS102TNUK Biology Department Lund UniversityEvolutionary Ecology UnitLund22362Sweden

Global temperatures are increasing rapidly affecting species *** if and how different species can adapt fast enough to keep up with increasing temperatures is of vital *** mechanism that can accelerate adaptation and promote evolutionary rescue is sexual *** different mechanisms by which sexual selection can facilitate adaptation are pre-and postcopulatory sexual ***,the relative effects of these different forms of sexual selection in promoting adaptation are ***,we present the results from an experimental study in which we exposed fruit flies Drosophila melanogaster to either no mate choice or 1 of 2 different sexual selection regimes(pre-and postcopulatory sexual selection)for 6 generations,under different thermal *** showed evidence of thermal adaptation under preco-pulatory sexual selection,but this effect was not detected in the postcopulatory sexual selection and the no choice mating *** further demonstrate that sexual dimorphism decreased when flies evolved under increasing temperatures,consistent with recent theory predicting more sexually concordant selection under environmental *** results suggest an important role for precopulatory sexual selection in promoting thermal adaptation and evolutionary rescue.

关键词： evolutionary rescue local adaptation climate change Drosophila sexual selection

Relativistic domain-wall dynamics in van der Waals antiferromagnet MnPs_(3)

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npj Computational Materials 2022年第1期8卷 27-35页

作者： Ignacio M.Alliati Richard F.L.evans Kostya s.Novoselov Elton J.G.santos school of Mathematics and Physics Queen’s University BelfastBelfastBT71NNUK Department of Physics The University of YorkYorkYO105DDUK Institute for Functional Intelligent Materials National University of SingaporeSingapore117544Singapore Institute for Condensed Matter Physics and Complex systems School of Physics and AstronomyThe University of EdinburghEdinburghEH93FDUK Higgs Centre for Theoretical Physics The University of EdinburghEdinburghEH93FDUK

The discovery of two-dimensional(2D)magnetic van der Waals(vdW)materials has flourished an endeavor for fundamental problems as well as potential applications in computing,sensing and storage *** particular interest are antiferromagnets,which due to their intrinsic exchange coupling show several advantages in relation to ferromagnets such as robustness against external magnetic *** we show that,despite of this cornerstone,the magnetic domains of recently discovered 2D vdW MnPs_(3)antiferromagnet can be controlled via magnetic fields and electric *** achieve ultrafast domain-wall dynamics with velocities up to~3000 m s^(−1)within a relativistic *** contraction and emission of spin-waves in the terahertz gap are observed with dependence on the edge termination of the *** results indicate that the implementation of 2D antiferromagnets in real applications can be further controlled through edge engineering which sets functional characteristics for ultrathin device platforms with relativistic features.

关键词： relativistic dynamics antiferromagnet

synthesis of layered LiMnO_2 by in situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

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Chinese science Bulletin 2005年第3期50卷 213-216页

作者： D.G.evans Key Laboratory of science and Technology of Controllable Chemical Reactions Ministry of EducationBeijing University of Chemical Tech- nologyBeijing 100029China

Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2s2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was characterized by XRD, ICP, TEM and Li-NMR. The results reveal that 7 orthorhombic LiMnO2 with high purity and good crystallin- ity can be obtained by this method. During electrochemical tests, a LiMnO2/Li cell shows an initial reversible capacity of 208 mAh·g?1 and a reversible capacity of 180 mAh·g?1 after 30 cycles at room temperature.

关键词： LiMnO2 氧化反应电化学特性锂离子电池分析方法

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Effects of the level and source of dietary physically effective fiber on feed intake, nutrient utilization, heat energy, ruminal fermentation,and milk production by Alpine goats

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Animal Nutrition 2024年第2期17卷 312-324页

作者： Raquel V.Lourencon Amlan K.Patra Luana P.s.Ribeiro Ryszard Puchala Wei Wang Terry A.Gipson Arthur L.Goetsch American Institute for Goat Research Langston University

Thirty-two primiparous and 31 multiparous Alpine goats were used to determine influences of diets varying in level and source of forage on performance in early to mid-lactation for 16 wk. Diets consisted of 40%, 50%, 60%, and 70% forage(designated as 40F, 50F, 60F, and 70F, respectively) with 60F and 70F containing coarsely ground grass hay(primarily orchardgrass) and 40F and 50F containing cottonseed hulls, alfalfa pellets, and coarsely ground wheat hay. Diets contained 15.9% to 16.3% crude protein and37.8%, 42.1%, 53.5%, and 55.4% neutral detergent fiber(NDF) with 10.0%, 15.8%, 50.1%, and 55.5% particle retention on a 19-mm s.eve, and 26.1%, 29.6%, 38.3%, and 40.0% physically effective NDF(pe NDF) for 40F,50F, 60F, and 70F, respectively. Dry matter intake(2.71, 2.75, 1.96, and 1.95 kg/d) and milk yield(2.82,2.71, 2.23, and 2.10 kg/d for 40F, 50F, 60F, and 70F, respectively) were lower(P s highest in forage. Digestion of organic matter was similar among diets(P > 0.05), but digestibility of NDF was greater(P spectively). Diet affected(P s(2.62%, 2.69%, 2.58%, and 2.52% for 40F, 50F, 60F, and 70F, respectively). Milk energy yield was greater(P s lowest in forage(7.51, 7.45, 5.68, and 5.34 MJ/d), although yield relative to dry matter intake was not affected(P > 0.05) by diet and was lower(P s vs. multiparous goats(2.71 and 3.09 MJ/kg). Ruminal p H and acetate proportion were greater for 60F and 70F than for the other diets and the proportion of butyrate was lower for the two diets highest in fiber. The mean lengths of time spent ruminating, eating, standing, and lying were not affected(P > 0.05) by diet or parity, but many interactions involving diet, period, hour, and parity were significant(P sion, lactational performance o

关键词： Physically effective fiber Alpine goat Lactation Ruminal fermentation Feeding behavior