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Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa

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Molecular Plant 2009年第5期2卷 1000-1014页

作者： Kerry H. Caffall Sivakumar Pattathil Sarah E. Phillips michael G. hahn Debra Mohnen Department of Biochemistry and Molecular Biology University of Georgia Athens GA 30602 USA Complex Carbohydrate Research Center BioEnergy Science Center 315 Riverbend Road University of Georgia Athens GA 30602 USA Department of Plant Biology University of Georgia Athens GA 30602 USA

Galacturonosyltransferase 1 （GAUT1） is an α1,4-D-galacturonosyltransferase that transfers galacturonic acid from uridine 5＇-diphosphogalacturonic acid onto the pectic polysaccharide homogalacturonan （Sterling et al., 2006）. The 25-member Arabidopsis thaliana GAUT1-related gene family encodes 15 GAUT and 10 GAUT-like （GATL） proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to GAUT1. Previous phylogenetic analyses of AtGAUTs indicated three clades： A through C. A comparative phylogenetic analysis of the Arabidopsis, poplar and rice GAUT families has sub-classified the GAUTs into seven clades： clade A-1 （GAUTs 1 to 3）; A-2 （GAUT4）; A-3 （GAUTs 5 and 6）; A-4 （GAUT7）; B-1 （GAUTs 8 and 9）; B-2 （GAUTs 10 and 11）; and clade C （GAUTs 12 to 15）. The Arabidopsis GAUTs have a distribution comparable to the poplar orthologs, with the exception of GAUT2, which is absent in poplar. Rice, however, has no orthologs of GAUTs 2 and 12 and has multiple apparent orthologs of GAUTs 1, 4, and 7 compared with eitherArabidopsis or poplar. The cell wall glycosyl residue compositions of 26 homozygous T-DNA insertion mutants for 13 of 15 Arabidopsis GAUTgenes reveal significantly and reproducibly different cell walls in specific tissues of gaut mutants 6, 8, 9, 10, 11, 12, 13, and 14 from that of wild-type Arabidopsis walls. Pectin and xylan polysaccharides are affected by the loss of GAUT function, as demonstrated by the altered galacturonic acid, xylose, rhamnose, galactose, and arabinose composition of distinct gaut mutant walls. The wall glycosyl residue compositional phenotypes observed among the gaut mutants suggest that at least six different biosynthetic linkages in pectins and/or xylans are affected by the lesions in these GAUTgenes. Evidence is also presented to support a role for GAUT11 in seed mucilage expansion and in seed wall and mucilage composition.

关键词： Carbohydrate metabolism cell walls Arabidopsis biosynthesis mutant pectin mucilage

Two Poplar Glycosyltransferase Genes, PdGATL 1.1 and PdGATL1.2, Are Functional Orthologs to PARVUS/AtGATL 1 in Arabidopsis

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Molecular Plant 2009年第5期2卷 1040-1050页

作者： Yingzhen Kong Gongke Zhou Utku Avci Xiaogang Gu Chelsea Jones Yanbin Yin Ying Xu michael G. hahn Complex Carbohydrate Research Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA BioEnergy Science Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA Computational System Biology Lab Dept. of Biochemistry and Molecular Biology and Institute of Bioinformatics The University of Georgia Athens GA 30602 USA

Several genes in Arabidopsis, including PARVUS/AtGATL1, have been implicated in xylan synthesis. However, the biosynthesis of xylan in woody plants, where this polysaccharide is a major component of wood, is poorly understood. Here, we characterize two Populus genes, PdGATL 1.1 and PdGATL 1.2, the closest orthologs to the Arabidopsis PARVUS/GATL1 gene, with respect to their gene expression in poplar, their sub-cellular localization, and their ability to complement the parvus mutation in Arabidopsis. Overexpression of the two poplar genes in the parvus mutant rescued most of the defects caused by the parvus mutation, including morphological changes, collapsed xylem, and altered cell wall monosaccharide composition. Quantitative RT-PCR showed that PdGATL1.1 is expressed most strongly in developing xylem of poplar. In contrast, PdGATL1.2 is expressed much more uniformly in leaf, shoot tip, cortex, phloem, and xylem, and the transcript level of PdGATL1.2 is much lower than that of PdGATL 1.1 in all tissues examined. Sub-cellular localization experiments showed that these two proteins are localized to both ER and Golgi in comparison with marker proteins resident to these sub-cellular compartments. Our data indicate that PdGATLI.1 and PdGATL1.2 are functional orthologs of PARVUS/ GATL1 and can play a role in xylan synthesis, but may also have role（s） in the synthesis of other wall polymers.

关键词： Arabidopsis thaliana poplar xylan glycosyltransferase.

Virus-Induced Gene Silencing Offers a Functional Genomics Platform for Studying Plant Cell Wall Formation

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Molecular Plant 2010年第5期3卷 818-833页

作者： Xiaohong Zhu Sivakumar Pattathil Koushik Mazumder Amanda Brehm michael G. hahn S.P. Dinesh-Kumar Chandrashekhar P. Joshi Biotechnology Research Center School of Forest Resources and Environmental Science Michigan Technological University Houghton MI 49931 USA BioEnergy Science Center Complex Carbohydrate Research Center University of Georgia 315 Riverbend Road Athens GA 30602 USA Department of Plant Biology University of Georgia Athens GA 30602 USA Section of Plant Biology and Genome Center University of California Davis CA 95616 USA Department of Bioenergy Science and Technology Chonnam National University Gwangju 500-757 Korea

Virus-induced gene silencing （VIGS） is a powerful genetic tool for rapid assessment of plant gene functions in the post-genomic era. Here, we successfully implemented a Tobacco Rattle Virus （TRV）-based VlGS system to study functions of genes involved in either primary or secondary cell wall formation in Nicotiana benthamiana plants. A 3-week post- VIGS time frame is sufficient to observe phenotypic alterations in the anatomical structure of stems and chemical composition of the primary and secondary cell walls. We used cell wall glycan-directed monoclonal antibodies to demonstrate that alteration of cell wall polymer synthesis during the secondary growth phase of VIGS plants has profound effects on the extractability of components from woody stem cell walls. Therefore, TRV-based VlGS together with cell wall component profiling methods provide a high-throughput gene discovery platform for studying plant cell wall formation from a bioenergy perspective.

关键词： Plant cell wall VIGS cellulose xylan lignin Nicotiana.

Multifaceted progress in high-field superconducting magnet mechanics

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Acta Mechanica Sinica 2024年第4期40卷 1-3页

作者： Xingzhe Wang Seungyong hahn Key Laboratory of Mechanics on Western Disaster and Environment Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea

High-field superconducting magnets are poised to revolutionize technologies,including particle accelerators,magnetic resonance imaging(MRI)machines,and fusion *** stand at the frontier of superconductor ***_(3)Sn wires,which operate at cold temperatures,along with rare-earth barium copper oxide(REBCO)coated conductors that include rare earth elements like Y,Gd,and Dy,are gaining *** high electrical efficiency in strong magnetic fields makes them particularly attractive for such advanced applications.

关键词： Nb_(3)Sn field earth

Solvation Effects on the Dielectric Constant of 1 M LiPF6 in Ethylene Carbonate:Ethyl Methyl Carbonate 3:7

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Energy & Environmental Materials 2024年第1期7卷 253-256页

作者： Julian Self Nathan T.hahn Kristin A.Persson Department of Chemical Engineering Polytechnique MontrealMontrealQC H3T 1J4Canada Department of Materials Science and Engineering University of CaliforniaBerkeleyCA 94720USA Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Material Physical and Chemical Sciences CenterSandia National LaboratoriesAlbuquerqueNM 87185USA

We report the dielectric constant of 1 M LiPF_(6)in EC:EMC 3∶7 w/w(ethylene carbonate/ethyl methyl carbonate)in addition to neat EC:EMC 3∶7 w/*** three Debye relaxations,the static permittivity value,or dielectric constant,is extrapolated to 18.5,which is compared to 18.7 for the neat solvent *** EC solvent is found to strongly coordinate with the Li^(+)cations of the salt,which results in a loss of dielectric contribution to the ***,the small amplitude and large uncertainty in relaxation frequency for EMC cloud definitive identification of the Li^(+)solvation ***,the loss of the free EC permittivity contribution due to Li^(+)solvation is almost completely balanced by the positive contribution of the associated LiPF_(6)salt,demonstrating that a significant quantity of dipolar ion pairs exists in 1 M LiPF_(6)in EC:EMC 3∶7.

关键词： batteries dielectric relaxation spectroscopy electrolytes

Enhanced activity and durability of FeCoCrMoCBY nanoglass in acidic hydrogen evolution reaction

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Journal of Materials Science & Technology 2024年第3期170卷 212-220页

作者： Mengyang Yan Shuangqin Chen Shangshu Wu Xuechun Zhou Shu Fu Di Wang Christian Kübel Horst hahn Si Lan Tao Feng Herbert Gleiter Institute of Nanoscience School of Material Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe 76021Germany

In the present work,a multi-element nanoglass(m-NG)of FeCoCrMoCBY is obtained first time by the laser ablation combined with inert gas condensation(laser-IGC)*** with the conventional rapid-quenched metallic glass(MG)with identical composition,the Fe-based m-NG demonstrates a superior performance as a self-supported electrocatalyst for hydrogen evolution reaction(HER)in acidic *** enhanced HER activity of m-NG is proposed to be closely related to its high en-ergy states,which is originated from the unique inhomogeneous nanostructures with a high density of low-coordinated ***,the Fe-based m-NG exhibits an outstanding comprehensive catalytic performance even beyond the commercial Pt/C catalyst in long-term test due to its self-optimization *** work not only opens the way to the preparation of m-NGs by the novel laser-IGC technique,but also makes a great contribution to developing low-cost,high-efficient,and super-durable HER electrocat-alysts in acidic environment.

关键词： Nanoglass Inert gas condensations High energy states Hydrogen evolution reactions

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计算超导螺线管磁体中电磁应力的解析方法

Acta Mechanica Sinica 2024年第4期40卷 4-20页

作者： Jeonghwan Park Kibum Choi Yufan Yan Jaemin Kim Seungyong hahn Department of Electrical and Computer Engineering Seoul National UniversitySeoul08826Republic of Korea Applied Superconductivity Center and Electric Power Institute Seoul National UniversitySeoul08826Republic of Korea

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来... 详细信息

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来的自保护行为至关重要.根据关键磁体设计参数(如目标中心场、背景磁场、内外绕组直径和外部径向堆叠),我们给出了可以从解析上确定高场超导磁体具有压缩径向应力的电磁-力学条件.本文提出的方法可以识别干绕线圈中径向匝间接触行为的3种不同模式:(1)完全分离;(2)完全接触;以及(3)混合模式(即部分分离和接触).文章随后提出一种使用完全压缩径向应力电磁-力学条件来计算干绕线圈中应力分布的解析方法.并通过有限元分析示例验证了解析方法与数值方法的良好一致性.文章结果可以帮助磁体工程师在早期设计阶段更好地概览高场超导磁体的电磁-力学行为.

关键词：高温超导背景磁场径向应力力学条件拉伸应力匝间接触行为混合模式

Screening-current-induced magnetic fields and strains in a compact REBCO coil in self field and background field

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Superconductivity 2024年第1期9卷 35-49页

作者： Yufan Yan Donghui Jiang Peng Song Jeonghwan Park Seungyong hahn Yunfei Tan Timing Qu Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China High Magnetic Field Laboratory Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhan 430074China

REBa_(2)Cu_(3)O_(7−x)(REBCO)coated conductors,owing to its high tensile strength and current‐carrying ability in a background field,are widely regarded a promising candidate in high‐field *** the great potentials,recent studies have highlighted the challenges posed by screening currents,which are featured by a highly nonuniform current distribution in the superconducting *** this paper,we report a comprehensive study on the behaviors of screening currents in a compact REBCO coil,specifically the screeningcurrent‐induced magnetic fields and *** were carried out in the self‐generated magnetic field and a background field,*** the self‐field condition,the full hysteresis of the magnetic field was obtained by applying current sweeps with repeatedly reversed polarity,as the nominal center field reached 9.17 T with a maximum peak current of 350 *** a background field of 23.15 T,the insert coil generated a center field of 4.17 T with an applied current of 170 ***,a total center field of 32.58 T was achieved before *** the sequential model and the coupled model considering the perpendicular field modification due to conductor deformation are *** comparative study shows that,for this coil,the electromagnetic–mechanical coupling plays a trivial role in self‐field conditions up to 9 *** contrast,with a high axial field dominated by the background field,the coupling effect has a stronger influence on the predicted current and strain *** discussions regarding the role of background field on the strains in the insert suggest potential design strategies to maximize the total center field.

关键词： Electromagnetic-mechanical analysis High‐field insert coil REBCO coated conductor Screening‐current‐induced magnetic field Screening‐current‐induced stress

Prenatal and postnatal factors associated with sudden infant death syndrome:an umbrella review of meta-analyses

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World Journal of Pediatrics 2024年第5期20卷 451-460页

作者： Tae Hyeon Kim Hyeri Lee Selin Woo Hayeon Lee Jaeyu Park Guillaume Fond Laurent Boyer Jong Woo hahn Jiseung Kang Dong Keon Yon Department of Medicine Kyung Hee University College of MedicineSeoulSouth Korea Center for Digital Health Medical Science Research InstituteKyung Hee University College of MedicineSeoulSouth Korea Department of Regulatory Science Kyung Hee UniversitySeoulSouth Korea Department of Biomedical Engineering Kyung Hee UniversityYonginSouth Korea CEReSS-Health Service Research and Quality of Life Center Assistance Publique des Hôpitaux de MarseilleAix-Marseille UniversityMarseilleFrance Department of Pediatrics Seoul National University College of MedicineSeoulSouth Korea Department of Pediatrics Seoul National University Bundang HospitalSeongnamSouth Korea Department of Anesthesia Critical Care and Pain MedicineMassachusetts General Hospital14913th StreetRoom 4140CharlestownBostonMAUSA Division of Sleep Medicine Harvard Medical SchoolBostonMAUSA Department of Pediatrics Kyung Hee University Medical CenterKyung Hee University College of Medicine23 Kyungheedae-roDongdaemun-guSeoul02447South Korea Department of Precision Medicine Kyung Hee University College of MedicineSeoulSouth Korea

Background Comprehensive quantitative evidence on the risk and protective factors for sudden infant death syndrome(SIDS)effects is *** investigated the risk and protective factors related to *** We conducted an umbrella review of meta-analyses of observational and interventional studies assessing SIDS-related ***/MEDLINE,Embase,EBSCO,and Google Scholar were searched from inception until January 18,*** extraction,quality assessment,and certainty of evidence were assessed by using A Measurement Tool Assessment Systematic Reviews 2 following PRISMA *** to observational evidence,credibility was graded and classified by class and quality of evidence(CE;convincing,highly suggestive,suggestive,weak,or not significant).Our study protocol was registered with PROSPERO(CRD42023458696).The risk and protective factors related to SIDS are presented as equivalent odds ratios(eORs).Results We identified eight original meta-analyses,including 152 original articles,covering 12 unique risk and protective factors for SIDS across 21 countries/regions and five *** risk factors,including prenatal drug exposure[eOR=7.84(95%CI=4.81–12.79),CE=highly suggestive],prenatal opioid exposure[9.55(95%CI=4.87–18.72),CE=suggestive],prenatal methadone exposure[9.52(95%CI=3.34–27.10),CE=weak],prenatal cocaine exposure[4.38(95%CI=1.95–9.86),CE=weak],prenatal maternal smoking[2.25(95%CI=1.95–2.60),CE=highly suggestive],postnatal maternal smoking[1.97(95%CI=1.75–2.22),CE=weak],bed sharing[2.89(95%CI=1.81–4.60),CE=weak],and infants found with heads covered by bedclothes after last sleep[11.01(95%CI=5.40–22.45),CE=suggestive],were *** the other hand,three protective factors,namely,breastfeeding[0.57(95%CI=0.39–0.83),CE=non-significant],supine sleeping position[0.48(95%CI=0.37–0.63),CE=suggestive],and pacifier use[0.44(95%CI=0.30–0.65),CE=weak],were also *** Based on the evidence,we propose several risk and protecti

关键词： Infant Protective factor Risk factor Sudden infant death syndrome Umbrella review