Structural Analysis of the Black-Legged Tick Saliva Protein Salp15

Salp15 is one of the proteins in the saliva of the tick Ixodes scapularis. Together with other biomolecules injected into the mammalian host at the biting site, it helps the tick to sustain its blood meal for days. Salp15 interferes with the cellular immune response of the mammalian host by inhibiting the activation of CD4⁺ T-lymphocytes. This function is co-opted by pathogens that use the tick as a vector and invade the host when the tick bites, such as Borrelia burgdorferi, the causative agent of Lyme borreliosis. Because of the immunity-suppressing role of Salp15, it has been proposed as a candidate for therapeutic applications in disorders of the immune system. The protein is produced as a 135-residue long polypeptide and secreted without its N-terminal signal 1–21 sequence. Detailed structural studies on Salp15 are lacking because of the difficulty in producing large amounts of the folded protein. We report the production of Salp15 and its structural analysis by NMR. The protein is monomeric and contains a flexible N-terminal region followed by a folded domain with mixed α + β secondary structures. Our results are consistent with a three-dimensional structural model derived from AlphaFold, which predicts the formation of three disulfide bridges and a free C-terminal cysteine.     

含生物功能基团磷脂胆碱的聚乳酸的合成反应

用天然甘油磷脂胆碱开环丙交酯,以获得具有仿生功能的生物降解聚乳酸.采用1H-NMR、FT-IR确证在聚合物结构中引入了生物功能基团磷脂胆碱.通过1H-NMR和GPC测定分子量及其分布,研究了反应时间和温度对聚合物分子量扣产率的影响,聚合物产率达80%以上.将磷脂引入聚乳酸链段中得到可全降解的、生物相容性好的磷脂高分子.这一新的思路可以用于合成一系列新型的药物载体和组织工程支架材料.     

车用涡轮增压器压气机叶轮振动特性分析

利用CAD软件对增压器的压气机叶轮进行了三维实体造型,并运用有限元分析软件I-DEAS对叶轮进行振动特性分析,得到了叶轮在不同转速下的固有频率值及相应振型,通过Matlab软件绘制Camp-bell图,找到了叶轮容易发生共振时的转速和激振频率.从而为该增压器叶轮的优化设计提供依据.     

Electricity market participation of wind farms: the success story of the Spanish pragmatism

In the last 10 years, more than 15 GW of wind power (Asociación Empresarial Eólica (Spanish Wind Energy Association), Nota de prensa (Press release) 17 de enero de 2008. http://www.aeeolica.org/doc/NP_080117_Espana_supera_los_15000_MW_eolicos.pdf) have been installed in Spain, of which more than 3.5 GW in 2007. Furthermore, plans are to reach 20 GW by 2010 and there are expectations of an installed capacity exceeding 40 GW by 2020. This article will present the innovative solutions for technical and economical integration that allow to reach such high level wind penetration objectives (the system peaks at around 44 GW and is almost isolated). It will be described how the regulation has evolved from a pure Feed-in-Tariff to a market+premium option, where technical and economic integration has been a priority. Today, approximately 97% of installed wind capacity accesses the Spanish wholesale electricity market. Market integration has been crucial, sending the correct signals to participants to look for the optimum technical solutions. Technical improvements have come from both wind power producers (fault-ride-through capabilities, visibility and controllability of wind power, power production forecasting, reactive power control) and the system operator (specific control centre dedicated to Renewable Energy Sources (RES), new security analysis tools, gaining technical confidence of wind capabilities).     

多相催化剂用于制备生物柴油的研究进展

生物柴油是绿色可再生能源,属环境友好型燃料,是常规的化学柴油的优良替代品。综述了酯交换方法生产生物柴油过程中的多相催化剂的研究进展,主要包括固体酸催化剂、固体碱催化剂、固定化酶的研究状况,并对催化油脂酯交换反应的多相催化剂的今后研究方向提出几点建议。     

Fe-substituted (La,Sr)TiO3 as potential electrodes for symmetrical fuel cells (SFCs)

In the work presented herein, the potential use of La₄Sr₈Ti_12−xFe_xO_38−δ (LSTF) materials as electrodes for a new concept of solid oxide fuel cells, symmetrical fuel cells (SFCs), is considered. Such fuel cells use simultaneously the same material as anode and cathode, which notably simplifies the assembly and further maintenance of the cells. Therefore, we search for materials showing high conductivity in a wide range of oxygen partial pressures in addition to certain degree of catalytic activity for the oxidation of the fuel and reduction of the oxidant, respectively. The preliminary electrochemical experiments performed reveal that the overall conductivity increases notably upon Fe substitution, being the main contribution electronic n-type. The fuel cell tests indicate that LSTF composites with YSZ and CeO₂ perform reasonably well under H₂ conditions, although the performance in methane is rather modest and require further optimisation.     

Design,fabrication and performance analysis of a 200 W PEM fuel cell short stack

A PEM fuel cell short stack of 200 W capacity, with an active area of 100 cm² has been designed and fabricated in-house. The status of unit cell performance was 0.55 W cm⁻². Based on the unit cell technology, a short stack has been developed. The proper design of uniform flow distribution, cooling plate and compressed end plate were important to achieve the best performance of the short stack. The performance of four cells stack was analyzed in static and dynamic modes. In the static mode of polarization curve, the stack has peak power density of 0.55 W cm⁻² (220 W) at 0.5 V per cell, when the voltage was scanning from low to high voltage (1.5–3.5 V), and resulted in minimum water flooding inside the stack. In this study a series of dynamic loadings were tested to simulate the vehicle acceleration. The fuel cell performances respond to dynamic loading influenced by the hydrogen/air stoichiometric, back pressure, and dynamic-loading time. It was needed high hydrogen stoichiometric and back pressure to maintain high dynamic performance. In the long-time stable power testing, the stack was difficult to maintain at high performance, due to the water flooding at high output power. An adjusting cathode back-pressure method for purging water was proposed to prevent the water flooding at flow channels and maintain the stable output power at 170 W (0.42 W cm⁻²).     

Aluminum and aluminum alloys as sources of hydrogen for fuel cell applications

Production of hydrogen using aluminum and aluminum alloys with aqueous alkaline solutions is studied. This process is based on aluminum corrosion, consuming only water and aluminum which are cheaper raw materials than other compounds used for in situ hydrogen generation, such as chemical hydrides. In principle, this method does not consume alkali because the aluminate salts produced in the hydrogen generation undergo a decomposition reaction that regenerates the alkali. As a consequence, this process could be a feasible alternative for hydrogen production to supply fuel cells. Preliminary results showed that an increase of base concentration and working solution temperature produced an increase of hydrogen production rate using pure aluminum. Furthermore, an improvement of hydrogen production rates and yields was observed varying aluminum alloys composition and increasing their reactive surface, with interesting results for Al/Si and Al/Co alloys. The development of this idea could improve yields and reduce costs in power units based on fuel cells which use hydrides as raw material for hydrogen production.     

高性能套管锻铣工具在威阳89井应用

为实现177.8mm套管的快速切割和高效锻铣,通过刀片尖端锐化处理改善套管切割时的受力,提高套管切割速度;采用非均匀布齿+内凹圆柱形切削齿,防止形成细长铁丝,有利于铁削返排,提高套管锻铣进尺和锻铣速度。威阳89井应用结果表明:套管切割时间仅为10min与常规工具相比,套管切割效率提高400%以上;平均单趟套管锻铣进尺10m,最大进尺13.3m,平均锻铣速度0.6m/h,最大速度0.7m/h,表明该工具能够实现177.8mm套管的快速切割和高效锻铣。研究成果对于提高老井侧钻和弃井的作业效率提供了支撑。     

进路宽度对无底柱分段崩落法放矿效果的影响

无底柱分段崩落采矿法结构参数对其放矿的损失与贫化有着较大的影响,本文采用单分段、单进路的放矿模型,研究了放矿过程中进路宽度对放矿量、回收率和贫化率的影响,分析了放矿效果产生变化的原因。实验发现:(1)随着进路宽度的增加,同一崩矿步距内的放矿量明显增加,进路口眉线处矿岩结拱现象大幅减少;(2)增加进路宽度可显著提高矿岩的流动性,进路宽度每增加0.5m,矿石回收率约提高1.3个百分点;(3)随着进路宽度的增加,矿石产生贫化的时间延迟,贫化率增长速度减小,但最终贫化率呈小幅度增加趋势。研究结果表明:放矿效果发生变化的主要原因一方面是进路宽度的增加提高了滑动微面以内的矿岩总量,因而大幅提高了放出的矿石量;另一方面是在出矿过程中,进路宽度越大,进路内矿岩被重复扰动的区域越小,进而减缓了废石的侵入速度。