Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Theoretical Investigations of the Chiral Transition of alpha-Amino Acid Confined in Various Sized Armchair Boron Nitride Nanotubes
No full textWe computationally study the chiral transition process of the alpha-Ala molecule under confined different sizes of armchair SWBNNTs to explore the confinement effect. We find that the influence of a confinement environment (in armchair SWBNNTs) on the alpha-Ala molecule would lead to different reaction pathways. Meanwhile, the preferred reaction pathway is also different in various sizes of armchair SWBNNTs, and their energy barriers for the rate limiting step decrease rapidly with the decreasing of the diameters of the nanotubes. It is obvious that significant decrease of the chiral transition energy barrier occurs compared with the isolated a -Ala molecule chirality conversion mechanism, by similar to 15.6 kcal mol(-1), highlighting the improvement in the activity the enantiomers of alpha -Ala molecule. We concluded that the confinement environment has a significant impact at the nanoscale on the enantiomer transformation process of the chiral molecule
科学家开发出太阳能电池用新型聚合物材料
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世界上80%以上的能源化石能源，弊端与危机不必赘述。据估算，全人类每年能量需求约为20太瓦，而太阳每年辐射到地球的能量约105太瓦，用之不竭。以有机半导体材料为基体的太阳能电池具有重量轻、成本低、灵活性等特点，已引起研究人员和创新型企业的极大关注。</p>
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俄罗斯科学家的贡献：（1）创建了适用于有机太阳能电池的新的<strong>共轭聚合物</strong>组，并发现使用单体单元在主链中无序排列的不规则共聚物，其光电特性明显优于链节以严格顺序交替排列的常规结构聚合物，其太阳能电池的效率大于7%，世界领先。（2）开发出用于有机太阳能电池、以<strong>富勒烯衍生物</strong>为基体的新型电子受体材料，能够保证有机太阳能电池在140℃高温下运行稳定。这是实现有机太阳能电池类设备长期稳定运行并得到实际应用的重要步骤。</p>
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研究成果发表在《Journal of Materials Chemistry》杂志材料上，有望对全球能源产业产生重大影响。</p
Understanding Mn-Based Intercalation Cathodes from Thermodynamics and Kinetics
No full textA series of Mn-based intercalation compounds have been applied as the cathode materials of Li-ion batteries, such as LiMn2O4, LiNi1-x-yCoxMnyO2, etc. With open structures, intercalation compounds exhibit a wide variety of thermodynamic and kinetic properties depending on their crystal structures, host chemistries, etc. Understanding these materials from thermodynamic and kinetic points of view can facilitate the exploration of cathodes with better electrochemical performances. This article reviews the current available thermodynamic and kinetic knowledge on Mn-based intercalation compounds, including the thermal stability, structural intrinsic features, involved redox couples, phase transformations as well as the electrical and ionic conductivity
Biomimetic Hybridization of Kevlar into Silk Fibroin: Nanofibrous Strategy for Improved Mechanic Properties of Flexible Composites and Filtration Membranes
No full textSilk, one of the strongest natural biopolymers, was hybridized with Kevlar, one of the strongest synthetic polymers, through a biomimetic nanofibrous strategy. Regenerated silk materials have outstanding properties in transparency, biocompatibility, biodegradability and sustainability, and promising applications as diverse as in pharmaceutics, electronics, photonic devices and membranes. To compete with super mechanic properties of their natural counterpart, regenerated silk materials have been hybridized with inorganic fillers such as graphene and carbon nanotubes, but frequently lose essential mechanic flexibility. Inspired by the nanofibrous strategy of natural biomaterials (e.g., silk fibers, hemp and byssal threads of mussels) for fantastic mechanic properties, Kevlar was integrated in regenerated silk materials by combining nanometric fibrillation with proper hydrothermal treatments. The resultant hybrid films showed an ultimate stress and Young's modulus two times as high as those of pure regenerated SF films. This is not only because of the reinforcing effect of Kevlar nanofibrils, but also because of the increasing content of silk fl-sheets. When introducing Kevlar nanofibrils into the membranes of silk nanofibrils assembled by regenerated silk fibroin, the improved mechanic properties further enabled potential applications as pressure-driven nanofiltration membranes and flexible substrates of electronic devices
Biochemical Characterization and Substrate Degradation Mode of a Novel Exotype beta-Agarase from Agarivorans gilvus WHO801
No full textAgarases are important hydrolytic enzymes for the biodegradation of agar. Understanding the degradation mode and hydrolysis products of agarases is essential for their utilization in oligosaccharide preparations. Herein, we cloned and expressed AgW1150B, a novel neoagarotetraose-forming beta-agarase from Agarivorans gilvus WHO801 that has high specific activity and a fast reaction rate. AgW1150B consists of a C-terminal glycoside hydrolase family 50 catalytic domain with two tandem noncatalytic carbohydrate-binding modules (CBMs) in the N-terminus (residues 45-214 and 236-442). AgWHSOB exhibited good enzymatic properties with high specific activity and catalytic efficiency (1523.2 U/mg and a V-max of 1700 mu mol/min/mg) under optimal hydrolysis conditions of pH 7.0 and 40 degrees C. Analysis of the hydrolysis products revealed that this enzyme is an exotype beta-agarase and that the dominant product of agarose or oligosaccharide degradation was neoagarotetraose. These findings suggest that AgVVH5OB could be utilized to yield abundant neoagarotetraose
The Improved Efficiency of Polymer Solar Cells by Fluorine Atoms at Ortho-Position of Alkxoyphenyl Group in Benzodithiophene (BDT) Units
No full textIn this article, two novel donor polymers containing fluorine atoms at ortho-position of alkxoyphenyl group in benzodithiophene (BDT) units are constructed. Compared with the reference polymer(P1) without fluorine atom, the polymers with fluorine atoms (P2 and P3) show their great different electrochemical properties, optical properties, morphology and hole mobility. Most significant change is their photovoltaic performances. The devices formed by P2 and P3 show much higher power conversion efficiency (PCE), 5.44% and 6.12%, respectively. The reasons should be that the incorporation of fluorine atom at ortho-position of alkoxyphenyl side chains increases the oxidation potential, decreases the highest occupied molecular orbit (HOMO) level of donor polymers, and thus increases the open circuit voltage (Voc) in device. Moreover, the linear hexyl side chain of P3 causes much higher PCE because it generates better molecular aggregation and hole transport in device
Synthesis and Properties of 2D Carbon-Graphdiyne
No full textCONSPECTUS: Graphdiyne (GDY) is a flat material comprising sp(2)- and sp-hybridized carbon atoms with high degrees of pi conjugation that features uniformly distributed pores. It is interesting not only from a structural point of view but also from the perspective of its electronic, chemical, mechanical, and magnetic properties. We have developed an in situ homocoupling reaction of hexaethynylbenzene on Cu foil for the fabrication of large-area ordered films of graphdiyne. These films are uniform and composed of graphdiyne multilayers. The conductivity of graphdiyne films, calculated at 2.52 x 10(-4) S m(-1), is comparable to that of Si, suggesting excellent semiconducting properties. Through morphology-controlled syntheses, we have prepared several well-defined graphdiyne structures (e.g., nanotubes, nanowires, and nanowalls) having distinct properties. The graphdiyne nanotube arrays and graphdiyne nanowalls exhibited excellent field emission performance, higher than that of some other semiconductors such as graphite and carbon nanotubes. These structures have several promising applications, for example, as energy storage materials and as anode materials in batteries. The unique atomic arrangement and electronic structure of graphdiyne also inspired us to use it to develop highly efficient catalysts; indeed, its low reduction potential and highly conjugated electronic structure allow graphdiyne to be used as a reducing agent and stabilizer for the electroless deposition of highly dispersed and surfactant-free Pd clusters. GDY-based three-dimensional (3D) nanoarchitectures featuring well-defined porous network structures can function as highly active cathodes for H-2 evolution. Heteroatom-doped GDY structures are excellent metal-free electrocatalysts for the oxygen reduction reaction (ORR). Its excellent electrocatalytic activity and inexpensive, convenient, and scalable preparation make GDY a promising candidate for practical and efficient energy applications; indeed, we have explored the application of GDY as a highly efficient lithium storage material and have elucidated the method through which lithium storage occurs in multilayer GDY. Lithium-ion batteries featuring GDY-based electrodes display excellent electrochemical performance, including high specific capacity, outstanding rate performance, and long cycle life. We have also explored the application of GDY in energy conversion and found that it exhibits excellent conductivity
A hemicellulose modified HZSM-5 and their application in the light olefins oligomerization to high-quality liquid fuels reaction
No full textThe biomass hemicellulose as well as initiating agents (ammonium persulfate and tetramethylethylenediamine) was first used as additive for traditional hydro-thermal synthesis for ZSM-5. The results demonstrate that the addition of biomass hemicellulose and initiating agents make the HZSM-5-Hc-S catalyst have larger BET surface areas, more mesopore structure, and stronger acidity. As a result, the HZSM-5-Hc-S catalyst exhibits high stability for the butene oligomerization with butene conversion of about 90% and diesel selectivity of about 86% during the 72 h time on stream
Strain-released method to enhance the photovoltaic performance in solution-processed organic solar cells
No full textTo release the steric-strain in largely fused molecular backbone and achieve the much planar molecules for efficient organic solar cells, a facile method was proposed by dividing the rigidly fused dibenzo-sexithiophene (DBST) units in FT3 with large molecular skeletons to two smaller building blocks to construct the electron donor-acceptor type compound FT4. As observed, much improved molecular co-planarity was achieved for FT4 in contrast to that of FT3, then leading to the higher charge carrier mobilities up to 6.7 x 10(-4) cm(2)V(-1)s(-1) by SCLC method. Meanwhile, FT4-based BHJ solar cells also exhibited much enhanced photovoltaic performance with the maximum PCE value of 3.07% and higher Jsc value of 8.23 mA/cm(2), which is only 2.13% and 5.67 mA/cm(2) for FT3-based solar cells. The results here indicated that the strain-released method, especially in the highly fused molecules, is beneficial to further improve their co-planarity, then leading to the high charge carrier mobilities and much enhanced photovoltaic performance in solar cells. (C) 2017 Elsevier Ltd. All rights reserved
A hybrid composite catalyst of Fe3O4 nanoparticles-based carbon for electrochemical reduction of oxygen
No full textThe design of efficient and cheap electrocatalysts for the oxygen reduction reaction (ORR) plays a key role for renewable energy technologies such as fuel cells and metal-air batteries. Using a simple and effective route, electronically conductive acetylene black (AB) was deliberately introduced into Fe3O4/HCS-600 with enough ORR active sites to be used as an ORR catalyst. The good homogenization of the electron conductor AB and the high intimate contact of Fe3O4/HCS-600 and AB in the composite catalyst provide the possibility of facile electron accessibility. The resulting composite catalyst exhibited a high and stable electrocatalytic activity for the ORR, which is better than Fe3O4/HCS-600 or AB alone. These features may offer potential for the development of efficient ORR catalysts with low cost for alkaline fuel cells