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Scale-up of biomass conversion using 1-ethyl-3-methylimidazolium acetate as the solvent

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Green Energy & Environment 2019年第4期4卷 432-438页

作者： Ling Liang Jipeng Yan Qian He Tina Luong Todd R.Pray Blake A.Simmons Ning Sun Advanced Biofuels and Bioproducts Process Development Unit Lawrence Berkeley National LaboratoryEmeryvilleCA94608USA Joint BioEnergy Institute Lawrence Berkeley National LaboratoryEmeryvilleCA94608USA

This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the *** pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was *** results show that 43 wt%of switchgrass was dissolved in IL after 2 h of pretreatment at 160℃ with 15 wt%solid loading.A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96%glucan and 98%xylan conversion.[C2C1Im][OAc]pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale(6 kg).The mass flow of the overall process was established and the major scale-up challenges of the process were identified.

关键词： Ionic liquid 1-Ethyl-3-methylimidazolium acetate Pretreatment Scale up Enzyme

In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

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Nano-Micro Letters 2019年第3期11卷 178-195页

作者： Maoyu Wang Líneyárnadóttir Zhichuan JXu Zhenxing Feng School of Chemical Biologicaland Environmental EngineeringOregon State UniversityCorvallisOR97331USA School of Materials Science and Engineering Nanyang Technological UniversitySingapore639798Singapore

Nanoscale electrocatalysts have exhibited promising activity and stability,improving the kinetics of numerous electrochemical reactions in renewable energy systems such as electrolyzers,fuel cells,and metal-air *** to the size effect,nano particles with extreme small size have high surface areas,complicated morphology,and various surface terminations,which make them different from their bulk phases and often undergo restructuring during the *** restructured materials are hard to probe by conventional ex-situ characterizations,thus leaving the true reaction centers and/or active sites difficult to ***,in situ techniques,particularly X-ray absorption spectroscopy(XAS),have become an important tool to obtain oxidation states,electronic structure,and local bonding environments,which are critical to investigate the electrocatalysts under real reaction *** this review,we go over the basic principles of XAS and highlight recent applications of in situ XAS in studies of nanoscale electrocatalysts.

关键词： X-ray absorption spectroscopy Electrocatalyst Nanoscale In situ experiments

Sulfur-doped graphene anchoring of ultrafine Au25 nanoclusters for electrocatalysis

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Nano Research 2021年第10期14卷 3509-3513页

作者： Mufan Li Bei Zhang Tao Cheng Sunmoon Yu Sheena Louisia Chubai Chen Shouping Chen Stefano Cestellos-Blanco William AGoddard III Peidong Yang Department of Chemistry University of CaliforniaBerkeleyCalifornia 94720USA Department of Materials Science and Engineering University of CaliforniaBerkeleyCalifornia 94720USA Chemical Science Division Lawrence Berkeley National LaboratoryBerkeleyCalifornia 94720USA Kavli Energy NanoScience Institute BerkeleyCalifornia 94720USA Materials and Process Simulation Center California Institute of TechnologyPasadenaCalifornia 91125USA

The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of *** demonstrate herein that chemical dopants on sulfur-doped graphene(S-G)can be utilized to stabilize ultrafine(sub-2 nm)Au_(25)(PET)18 clusters to enable stable nitrogen reduction reaction(NRR)without significant structural *** Au_(25)@S-G exhibits an ammonia yield rate of 27.5μgNH_(3)·mgAu^(-1)·h^(-1)at-0.5 V with faradic efficiency of 2.3%.More importantly,the anchored clusters preserve~80%NRR activity after four days of continuous operation,a significant improvement over the 15%remaining ammonia production rate for clusters loaded on undoped graphene tested under the same *** labeling experiments confirmed the ammonia was a direct reaction product of N2 feeding gas instead of other chemical ***-situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy of post-reaction catalysts reveal that the sulfur dopant plays a critical role in stabilizing the chemical state and coordination environment of Au atoms in *** ReaxFF molecular dynamics(RMD)simulation confirmed the strong interaction between Au nanoclusters(NCs)and *** substrate-anchoring process could serve as an effective strategy to study ultrafine nanoclusters’electrocatalytic behavior while minimizing the destruction of the under-coordinated surface motif under harsh electrochemical reaction conditions.

关键词： gold nanoclusters sulfur-doped graphene nitrogen reduction reaction electrocatalysis anchoring effect

Temporal and spatial study of differently charged ions emitted by ns-laser-produced tungsten plasmas using time-of-flight mass spectroscopy

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Plasma Science and Technology 2021年第9期23卷 176-183页

作者： Ding WU George C-Y CHAN Xianglei MAO Yu LI Richard E RUSSO Hongbin DING Vassilia ZORBA School of Physics Dalian University of TechnologyDalian 116024People's Republic of China Lawrence berkeley National Laboratory BerkeleyCA 94720United States of America Department of Mechanical Engineering University of CaliforniaBerkeleyCA 94720United States of America

Tungsten(W)is an important material in tokamak walls and *** W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using laser-ablation-based diagnostics such as laser-induced breakdown spectroscopy and laser-induced ablation *** this work,we investigate the temporal and spatial evolutions of differently charged ions in a nanosecond-laser-produced W plasma in vacuum using time-of-flight mass *** with different charge states from 1 to 7(W+to W7+)are all *** temporal evolutions of the differently charged ions show that ions with higher charge states have higher velocities,indicating that space separation occurs between the differently charged ion ***-resolved mass spectroscopy measurements further demonstrate the separation *** temporal profile can be accurately fitted by a shifted Maxwell–Boltzmann distribution,and the velocities of the differently charged ions are also obtained from the *** is found that the ion velocities increase continuously from the measured position of 0.75 cm to 2.25 cm away from the target surface,which indicates that the acceleration process lasts through the period of plasma *** acceleration and space separation of the differently charged ions confirm that there is a dynamic plasma sheath in the laser-produced plasma,which provides essential information for the theoretical laser-ablation model with plasma formation and expansion.

关键词： laser ablation temporal and spatial evolution time-of-flight mass spectroscopy spatial separation differently charged ions

Molecular Evolution of VEF-Domain-Containing PcG Genes in Plants

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Molecular Plant 2009年第4期2卷 738-754页

作者： Ling-Jing Chen Zhao-Yan Diao Chelsea Specht Z. Renee Sung Department of Plant and Microbial Biology University of California Berkeley CA 94720-3102 USA

Arabidopsis VERNALIZATION2 （VRN2）, EMBRYONIC FLOWER2 （EMF2）, and FERTILIZATION-INDEPENDENT SEED2 （FIS2） are involved in vernalization-mediated flowering, vegetative development, and seed development, respectively. Together with Arabidopsis VEF-L36, they share a VEF domain that is conserved in plants and animals. To investigate the evolution of VEF-domain-containing genes （VEF genes）, we analyzed sequences related to VEF genes across land plants. To date, 24 full-length sequences from 11 angiosperm families and 54 partial sequences from another nine families were identified. The majority of the full-length sequences identified share greatest sequence similarity with and possess the same major domain structure as Arabidopsis EMF2. EMF2-1ike sequences are not only widespread among angiosperms, but are also found in genomic sequences of gymnosperms, lycophyte, and moss. No FIS2- or VEF-L36-1ike sequences were recovered from plants other than Arabidopsis, including from rice and poplar for which whole genomes have been sequenced. Phylogenetic analysis of the full-length sequences showed a high degree of amino acid sequence conservation in EMF2 homologs of closely related taxa. VRN2 homologs are recovered as a clade nested within the larger EMF2 clade. FIS2 and VEF-L36 are recovered in the VRN2 clade. VRN2 clade may have evolved from an EMF2 duplication event that occurred in the rosids prior to the divergence of the eurosid I and eurosid II lineages. We propose that dynamic changes in genome evolution contribute to the generation of the family of VEF-domain-containing genes, Phylogenetic analysis of the VEF domain alone showed that VEF sequences continue to evolve following EM F2NRN2 divergence in accordance with species relationship. Existence of EMF2-1ike sequences in animals and across land plants suggests that a prototype form of EMF2 was present prior to the divergence of the plant and animal lineages. A proposed sequence of events, based on domain organization and

关键词： VEF EMF2 FIS2 VRN2 VEF-L36 Arabidopsis PcG phylogeny evolution.

Early Stage of Oxidation on Titanium Surface by Reactive Molecular Dynamics Simulation

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Computers, Materials & Continua 2018年第4期55卷 177-188页

作者： Liang Yang Caizhuang Wang Shiwei Lin Yang Cao Xiaoheng Liu School of chemical Engineering Nanjing University of science&TechnologyNanjing 210094China Materials and Chemical Engineering Hainan UniversityHaikou570228China Ames laboratory and Department of Physics Iowa State UniversityAmesIA 50011USA

Understanding of metal oxidation is very critical to corrosion control,catalysis synthesis,and advanced materials *** oxidation is a very complex phenomenon,with many different processes which are coupled and involved from the onset of *** this work,the initial stage of oxidation on titanium surface was investigated in atomic scale by molecular dynamics(MD)simulations using a reactive force field(ReaxFF).We show that oxygen transport is the dominant process during the initial *** simulation also demonstrate that a compressive stress was generated in the oxide layer which blocked the oxygen transport perpendicular to the Titanium(0001)surface and further prevented oxidation in the deeper *** mechanism of initial oxidation observed in this work can be also applicable to other self-limiting oxidation.

关键词： Reactive force field metal oxidation self-limiting oxidation Titanium(0001)surface molecular dynamics simulation compressive stress

Intraparticle Charge Delocalization through Conjugated Metal-Ligand Interfacial Bonds:Effects of Metal d Electrons

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Chinese Journal of Chemical Physics 2018年第4期31卷 433-438,613页

作者： Yi Peng EduardoY.Hirata WanzhangPan Limei Chen Jia En Lu Shaowei Chen Department of Chemistry and Biochemistry University of CaliforniaSanta CruzCalifornia 95054US

Intraparticle charge delocalization occurs when metal nanoparticles are functionalized with organic capping ligands through conjugated rnetal-ligand interfacial bonds. In this study, metal nanoparticles of 5d metals （Ir, Pt, and Au） and 4d metals （Ru, Rh, and Pd） were prepared and capped with ethynylphenylacetylene and the impacts of the number of metal d electrons on the nanoparticle optoelectronic properties were examined. Both FTIR and photoluminescence measurements indicate that intraparticle charge delocalization was en- hanced with the increase of the number of d electrons in the same period with palladium being an exception.

关键词： Nanoparticle d Electron Acetylene Interracial bond Intraparticle charge delocalization

Laser requirements for a laser fusion energy power plant

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High Power Laser Science and Engineering 2013年第1期1卷 2-10页

作者： Stephen E.Bodner Andrew J.Schmitt John D.Sethian 550 Carolina Meadows Villas Chapel Hill NC 27517United States Plasma Physics Division Naval Research LaboratoryWashington DC 20375United States

We will review some of the requirements for a laser that would be used with a laser fusion energy power plant, including frequency, spatial beam smoothing, bandwidth, temporal pulse shaping, efficiency, repetition rate, and reliability. The lowest risk and optimum approach uses a krypton fluoride gas laser. A diode-pumped solid-state laser is a possible contender.

关键词： laser fusion energy

热力学和光谱学方法在锕系元素络合化学研究中的应用(英文)

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化学进展 2011年第7期23卷 1295-1307页

作者：饶林峰美国劳伦斯伯克利国立实验室加利福尼亚伯克利94720

为了安全地,可持续地发展和利用核能,必须建立新一代的,包括先进的锕系元素分离流程及安全可靠的核废物处理/处置流程在内的核燃料循环体系。由于锕系元素络合化学的基础研究在核燃料循环体系的开发中起着十分重要的作用,近年来锕系元... 详细信息

为了安全地,可持续地发展和利用核能,必须建立新一代的,包括先进的锕系元素分离流程及安全可靠的核废物处理/处置流程在内的核燃料循环体系。由于锕系元素络合化学的基础研究在核燃料循环体系的开发中起着十分重要的作用,近年来锕系元素与各种配体的络合成为相当热门的研究课题。有的配体作为萃取剂或反萃剂用于后处理过程中锕系元素的分离,另一些配体存在于环境中通过络合或氧化还原反应来决定锕系元素的物种形式及迁移行为。因此,只有在基础科学的层面上来研究锕系元素的络合化学,才能有助于解释和预测锕系元素在分离过程和环境迁移中的行为。许多热力学和光谱学方法可以用来研究锕系元素在溶液中的络合反应,提供关于锕系元素络合物的本性(如:离子价/共价,外界/内界络合),能量(如:自由能,热焓,热熵,热容)和结构的基础科学信息。本文有选择地介绍几种近年来常用于锕系元素络合化学研究的热力学和光谱学方法,包括微量热学,吸收光谱和荧光光谱学,以及X射线吸收光谱学。本文重点不在阐述方法原理,而在举例说明使用这些方法能得到的科学信息。

关键词：锕系元素络合热力学光谱学