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分析矫形器的产品设计以及材料的应用现状,探讨矫形器的研究方向。以患者的需求和矫形器目前的发展状况为依据,探讨了矫形器设计中的重点问题,并对矫形器材料的应用展开了分析和论述。矫形器的设计应该从患者需求出发,满足生理需求和心理需求,坚持设计以人为中心的指导思想,同时注意安全性、舒适性、艺术性、定制化和智能化问题;目前矫形器的材料主要是是合成高分子材料及其复合材料,它们以良好的机械性能和生物性能广泛应用于矫形器领域。 相似文献
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聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHA)是许多细菌在非平衡生长条件下在胞内积累的以颗粒状态存在的碳源和能源储藏物质。PHA因其具有生物可降解性、生物相容性等许多良好的材料性质、可以作为化学合成塑料未来的替代品而引起广泛关注。但由短链脂肪酸或单一脂肪酸单体合成的PHA的材料性质具有局限性,需要利用多种单体合成满足实际需求的PHA材料。PHA合成酶的底物特异性和PHA合成代谢途径决定着PHA的单体组成情况,进而影响着PHA的理化特性和材料性能。因此需要对PHA合成酶进行改造,扩展其对底物的特异性。另一方面需要构建新的PHA合成代谢途径,能合成出一些不常见的且性能优良的PHA材料。综述了近些年对PHA合成酶改造的研究及PHA代谢途径构建的研究进展。 相似文献
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蛋白质类医用高分子是一类重要的功能高分子材料,在生物医学领域有着广泛的应用。随着现代生物技术特别是分子生物学技术的发展,微生物合成医用高分子材料已成为可能。微生物合成除了大规模、低成本的特点外,还可对蛋白质高分子进行分子设计,从而赋予其新的材料性能,以满足不同的需要。该文综述了蛋白质类医用高分子(胶原与明胶、弹性蛋白、丝蛋白)微生物合成的研究进展,指出微生物合成的原理方法及应用现状,并对其发展前景进行了展望。 相似文献
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摘要:天然和合成聚合物因优良的特性引起了越来越多研究者的兴趣,并已被广泛用于人类的日常生活中。聚苹果酸(Polymalic acid,PMLA)一种天然的高分子聚酯材料,具有良好的生物相容性和完全生物降解性,其衍生物同样具有优异的生物学性能,被广泛应用于众多领域中。本文就聚苹果酸及其衍生物的结构、性质和合成方法进行了概述,并全面总结了其在制药和其他领域的应用研究现状,最后对未来发展方向进行了展望。 相似文献
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本文设计合成了一种可湿法加工单层发光材料—2-(4-(N-辛基二苯胺基)-8-(4-(N-辛基咔唑基)二-苯并噻吩砜,目标分子的结构采用MS,NMR及元素分析进行表征。测试了其进行光致发光及电致发光性能,其中电致发光性能通过建构四种不同的器件结构进行测定,结果发现,器件的最大发光亮度为1298cd/m2,效率为1.52cd/A。 相似文献
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以酶促聚合为代表的绿色高分子合成途径,以其反应条件温和、产物多分散性低、无金属催化剂残留、高度立体和区位选择性等优势,成为医用高分子材料合成领域中的研究热点。目前,氧化还原酶、水解酶、转移酶均成功应用于聚合反应,其中脂肪酶催化的缩聚反应及开环聚合反应研究最为广泛,同时,以可逆加成-断裂链转移聚合和原子转移自由基聚合为代表的酶促可逆失活自由基聚合得到了快速发展。针对酶促聚合中单体及合成产物结构与性能单一、应用范围有限等缺陷,基于酶促聚合与原子转移自由基聚合、开环易位聚合等反应的偶联,制备了多种不同结构与性能的聚合物材料,推动了上述材料在药物与基因递送领域中的应用。本文综述了脂肪酶催化聚合、酶促可逆失活自由基聚合、酶促化学偶联催化等方面的研究进展,并探讨了目前研究的局限性和未来研究方向。 相似文献
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Nengwu Zhu Xi Chen Ting Zhang Pingxiao Wu Ping Li Jinhua Wu 《Bioresource technology》2011,102(1):422-426
Surface modifications of anode materials are important for enhancing power generation of microbial fuel cell (MFC). Membrane free single-chamber air-cathode MFCs, MFC-A and MFC-N, were constructed using activated carbon fiber felt (ACF) anodes treated by nitric acid and ethylenediamine (EDA), respectively. Experimental results showed that the start-up time to achieve the maximum voltages for the MFC-A and MFC-N was shortened by 45% and 51%, respectively as compared to that for MFC-AT equipped with an unmodified anode. Moreover, the power output of MFCs with modified anodes was significantly improved. In comparison with MFC-AT which had a maximum power density of 1304 mW/m2, the MFC-N achieved a maximum power density of 1641 mW/m2. The nitric acid-treated anode in MFC-A increased the power density by 58% reaching 2066 mW/m2. XPS analysis of the treated and untreated anode materials indicated that the power enhancement was attributable to the changes of surface functional groups. 相似文献
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A Robust Approach for Efficient Sodium Storage of GeS2 Hybrid Anode by Electrochemically Driven Amorphization
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Sodium ion batteries (NIBs) have become attractive promising alternatives to lithium ion batteries in a broad field of future energy storage applications. The development of high‐performance anode materials has become an essential factor and a great challenge toward satisfying the requirements for NIBs, advancement. This work is the first report on GeS2 nanocomposites uniformly distributed on reduced graphene oxide (rGO) as promising anode materials for NIBs prepared via a facile hydrothermal synthesis and a unique carbo‐thermal annealing. The results show that the GeS2/rGO hybrid anode yields a high reversible specific capacity of 805 mA h g?1 beyond the theoretical capacity, an excellent rate capability of 616 mA h g?1 at 5 A g?1, and a cycle retention of 89.4% after 100 cycles. A combined ex situ characterization study reveals that the electrochemically driven amorphization plays a key role in achieving efficient sodium storage by accommodating excess sodium ions in the electrode materials. Understanding the sequential conversion‐alloying reaction mechanism for GeS2/rGO hybrid anodes provides a new approach for developing high‐performance energy storage applications. 相似文献
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Guojin Liang Funian Mo Hongfei Li Zijie Tang Zhuoxin Liu Donghong Wang Qi Yang Longtao Ma Chunyi Zhi 《Liver Transplantation》2019,9(32)
Conventional charge storage mechanisms for electrode materials are common in widely exploited insertion/extraction processes, while some sporadic examples of chemical conversion mechanisms exist. It is perceived to be of huge potential, but it is quite challenging to develop new battery chemistry to promote battery performance. Here, an initiating and holistic deposition–dissolution battery mechanism for both cathodes and anodes is reported. A MnO2–Cu battery based on this mechanism demonstrates outstanding energy density (27.7 mWh cm?2), power density (1232 mW cm?2), high reversibility, and unusual Coulombic efficiency. It can be charged to 0.8 mAh cm?2 within 42 s and possessees a stable rate cyclability within vastly varied discharging current density (4–64 mA cm?2). Moreover, the deposition–dissolution mechanism can be universally adopted and derived such that the corresponding MnO2–Zn and MnO2–Bi batteries are successfully constructed. The material selection principle, deposition–dissolution behaviors of cathode/anode materials, and battery performance are systematically elaborated. Since the electrodeposition chemistry is capable of involving a large family of materials, for example, metal oxides as cathode materials, or metals as anode materials, the research could be a model system to open a door to explore new aqueous battery materials and chemistry. 相似文献
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Metal‐organic coordination frameworks have been widely used as efficient precursors for the preparation of functional carbon‐based materials with various nanostructures. However, to date, the design of 2D carbon nanostructures from single coordination frameworks remains a great challenge. Herein, an efficient strategy for the fabrication of N‐rich porous carbon nanosheets from 2D Zn‐hexamine coordination framework nanosheets is developed. Remarkably, the N‐doping level of carbon nanosheets can attain 16.54 at%. In addition, the thickness of the carbon nanosheets can effectively be tuned by simply adjusting the molar ratio of the starting materials. As a proof‐of‐concept application, the as‐prepared carbon nanosheets as an anode material for sodium‐ion batteries exhibit an ultrafast sodium storage capability of 194 mAh g?1 even at 10 A g?1. As far as it is known, such a high‐rate capability has been rarely achieved in previous studies on carbonaceous anode materials for Na‐ion storage. Moreover, this approach is readily controllable and could be extended to prepare a series of 2D N‐doped carbon‐based nanomaterials on a large scale. 相似文献
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The dendritic structure is a disastrous problem of lithium metal batteries as well as other metal rechargeable batteries. The dendritic structures are usually caused by diffusion limitation. Here, a novel strategy is reported to inhibit lithium dendrites based on the understanding of their formation mechanism. An alternating current field perpendicular to the anode is set up, which promotes Li+ movement along the anode surface and prevents ions' deposition on the tips from forming dendrites. Furthermore, an external direct current field parallel to the current is employed, which accelerates the transport of Li+ in electrolytes to mitigate the concentration gradient nearby the anode and thus inhibits the formation of dendritic structures. A simultaneous employment of these two fields gains five times increase of the lifespan of batteries at the high charging current density of 2 mA cm?2, confirming the effectiveness of this strategy in protecting the metal anode and inhibiting lithium dendrites. This strategy may have a wide feasibility since it does not change the materials and structures of batteries. 相似文献
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Yeonguk Son Jiyoung Ma Namhyung Kim Taeyong Lee Yoonkwang Lee Jaekyung Sung Seong‐Hyeon Choi Gyutae Nam Hyeyoung Cho Youngshin Yoo Jaephil Cho 《Liver Transplantation》2019,9(11)
Pseudocapacitive materials have been highlighted as promising electrode materials to overcome slow diffusion‐limited redox mechanism in active materials, which impedes fast charging/discharging in energy storage devices. However, previously reported pseudocapacitive properties have been rarely used in lithium‐ion batteries (LIBs) and evaluation methods have been limited to those focused on thin‐film‐type electrodes. Hence, a nanocage‐shaped silicon–carbon composite anode is proposed with excellent pseudocapacitive qualities for LIB applications. This composite anode exhibits a superior rate capability compared to other Si‐based anodes, including commercial silicon nanoparticles, because of the higher pseudocapacitive contribution coming from ultrathin Si layer. Furthermore, unprecedent 3D pore design in cage shape, which prevents the particle scale expansion even after full lithiation demonstrates the high cycling stability. This concept can potentially be used to realize high‐power and high‐energy LIB anode materials. 相似文献
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Advanced Phosphorus‐Based Materials for Lithium/Sodium‐Ion Batteries: Recent Developments and Future Perspectives
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High‐performance and lost‐cost lithium‐ion and sodium‐ion batteries are highly desirable for a wide range of applications including portable electronic devices, transportation (e.g., electric vehicles, hybrid vehicles, etc.), and renewable energy storage systems. Great research efforts have been devoted to developing alternative anode materials with superior electrochemical properties since the anode materials used are closely related to the capacity and safety characteristics of the batteries. With the theoretical capacity of 2596 mA h g?1, phosphorus is considered to be the highest capacity anode material for sodium‐ion batteries and one of the most attractive anode materials for lithium‐ion batteries. This work provides a comprehensive study on the most recent advancements in the rational design of phosphorus‐based anode materials for both lithium‐ion and sodium‐ion batteries. The currently available approaches to phosphorus‐based composites along with their merits and challenges are summarized and discussed. Furthermore, some present underpinning issues and future prospects for the further development of advanced phosphorus‐based materials for energy storage/conversion systems are discussed. 相似文献
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Potassium ion hybrid capacitors have great potential for large‐scale energy devices, because of the high power density and low cost. However, their practical applications are hindered by their low energy density, as well as electrolyte decomposition and collector corrosion at high potential in potassium bis(fluoro‐sulfonyl)imide‐based electrolyte. Therefore, anode materials with high capacity, a suitable voltage platform, and stability become a key factor. Here, N‐doping carbon‐coated FeSe2 clusters are demonstrated as the anode material for a hybrid capacitor, delivering a reversible capacity of 295 mAh g?1 at 100 mA g?1 over 100 cycles and a high rate capability of 158 mAh g?1 at 2000 mA g?1 over 2000 cycles. Meanwhile, through density functional theory calculations, in situ X‐ray diffraction, and ex situ transmission electron microscopy, the evolution of FeSe2 to Fe3Se4 for the electrochemical reaction mechanism is successfully revealed. The battery‐supercapacitor hybrid using commercial activated carbon as the cathode and FeSe2/N‐C as the anode is obtained. It delivers a high energy density of 230 Wh kg?1 and a power density of 920 W kg?1 (the energy density and power density are calculated based on the total mass of active materials in the anode and cathode). 相似文献
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Bin Cao Qing Zhang Huan Liu Bin Xu Shilin Zhang Tengfei Zhou Jianfeng Mao Wei Kong Pang Zaiping Guo Ang Li Jisheng Zhou Xiaohong Chen Huaihe Song 《Liver Transplantation》2018,8(25)
As an emerging electrochemical energy storage device, potassium‐ion batteries (PIBs) have drawn growing interest due to the resource‐abundance and low cost of potassium. Graphite‐based materials, as the most common anodes for commercial Li‐ion batteries, have a very low capacity when used an anode for Na‐ion batteries, but they show reasonable capacities as anodes for PIBs. The practical application of graphitic materials in PIBs suffers from poor cyclability, however, due to the large interlayer expansion/shrinkage caused by the intercalation/deintercalation of potassium ions. Here, a highly graphitic carbon nanocage (CNC) is reported as a PIBs anode, which exhibits excellent cyclability and superior depotassiation capacity of 175 mAh g?1 at 35 C. The potassium storage mechanism in CNC is revealed by cyclic voltammetry as due to redox reactions (intercalation/deintercalation) and double‐layer capacitance (surface adsorption/desorption). The present results give new insights into structural design for graphitic anode materials in PIBs and understanding the double‐layer capacitance effect in alkali metal ion batteries. 相似文献
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Performance and microbial ecology of air-cathode microbial fuel cells with layered electrode assemblies 总被引:1,自引:0,他引:1
Microbial fuel cells (MFCs) can be built with layered electrode assemblies, where the anode, proton exchange membrane (PEM),
and cathode are pressed into a single unit. We studied the performance and microbial community structure of MFCs with layered
assemblies, addressing the effect of materials and oxygen crossover on the community structure. Four MFCs with layered assemblies
were constructed using Nafion or Ultrex PEMs and a plain carbon cloth electrode or a cathode with an oxygen-resistant polytetrafluoroethylene
diffusion layer. The MFC with Nafion PEM and cathode diffusion layer achieved the highest power density, 381 mW/m2 (20 W/m3). The rates of oxygen diffusion from cathode to anode were three times higher in the MFCs with plain cathodes compared to
those with diffusion-layer cathodes. Microsensor studies revealed little accumulation of oxygen within the anode cloth. However,
the abundance of bacteria known to use oxygen as an electron acceptor, but not known to have exoelectrogenic activity, was
greater in MFCs with plain cathodes. The MFCs with diffusion-layer cathodes had high abundance of exoelectrogenic bacteria
within the genus Geobacter. This work suggests that cathode materials can significantly influence oxygen crossover and the relative abundance of exoelectrogenic
bacteria on the anode, while PEM materials have little influence on anode community structure. Our results show that oxygen
crossover can significantly decrease the performance of air-cathode MFCs with layered assemblies, and therefore limiting crossover
may be of particular importance for these types of MFCs. 相似文献