Energy harvesting by implantable abiotically catalyzed glucose fuel cells

Implantable glucose fuel cells are a promising approach to realize an autonomous energy supply for medical implants that solely relies on the electrochemical reaction of oxygen and glucose. Key advantage over conventional batteries is the abundant availability of both reactants in body fluids, rendering the need for regular replacement or external recharging mechanisms obsolete. Implantable glucose fuel cells, based on abiotic catalysts such as noble metals and activated carbon, have already been developed as power supply for cardiac pacemakers in the late-1960s. Whereas, in vitro and preliminary in vivo studies demonstrated their long-term stability, the performance of these fuel cells is limited to the μW-range. Consequently, no further developments have been reported since high-capacity lithium iodine batteries for cardiac pacemakers became available in the mid-1970s. In recent years research has been focused on enzymatically catalyzed glucose fuel cells. They offer higher power densities than their abiotically catalyzed counterparts, but the limited enzyme stability impedes long-term application. In this context, the trend towards increasingly energy-efficient low power MEMS (micro-electro-mechanical systems) implants has revived the interest in abiotic catalysts as a long-term stable alternative. This review covers the state-of-the-art in implantable abiotically catalyzed glucose fuel cells and their development since the 1960s. Different embodiment concepts are presented and the historical achievements of academic and industrial research groups are critically reviewed. Special regard is given to the applicability of the concept as sustainable micro-power generator for implantable devices.     

三相电压不对称时谐波电流检测方法

针对现有检测方法在三相电压不对称或畸变时存在的一些缺陷,提出了一种新的同步坐标变换的检测方法。它能实时检测出不对称三相电路中的基波正序有功电流以及无功电流与不对称分量、谐波电流的和,从而可直接应用于三相三线制或三相四线制系统的综合补偿。该检测方法无需对三相电压进行锁相和滤波,避免了由此带来的检测误差。理论推导和仿真结果验证了所提方法的正确性。     

长螺旋旋喷搅拌水泥土帷幕桩及其应用

介绍了一种新的专利技术——长螺旋旋喷搅拌水泥土桩,尤其适用于北京等硬土地区在已施护坡桩之间做帷幕,克服砂卵石等硬地层,比其它方法在技术可靠、施工高效、安全文明、经济环保4方面有明显优势。同时介绍了该技术在北京大学留学生公寓楼基坑工程中的应用,确保了西侧5栋高教住宅楼的安全和正常使用。     

小角度入射法测油垢厚度的初步实验研究

本文用石蜡模拟油垢,用60Co放射源的1.25MeV平均能量的γ射线小角度入射,分别在小角度和大角度散射角内接收散射γ光子数,发现散射γ计数与被测石蜡厚度之间存在线性关系。实验结果表示小角度散射法结果相对于大角度散射法结果好一些。     

Transient modeling of combined conduction and radiation in wood fibre insulation and comparison with experimental data

This is an innovative study of wood wool used for building insulation and the reported results could be important for improving the cooling and the heating efficiency of buildings. Wood fibre boards are non-grey, absorbing and scattering media. The radiative properties of the wood wool (albedo, optical thickness and phase function coefficients) were identified using an inverse method based on infrared experimental measurements of reflection and transmission. The radiative part was then found negligible with respect to the phonic part in steady state for the material tested. Transient one-dimensional coupled radiative and conductive heat transfer was solved in a wood wool material. The transient numerical results were validated by comparing them with fluxmeter measurements when temperatures were fixed at the boundaries. The temperatures and the heat capacity had strong influence on the transient numerical results. Finally, our computations showed that a purely conductive model gives the same fluxes at the boundary as the coupled radiative-conductive model.     

An improved EAS brick element for finite deformation

A new enhanced assumed strain brick element for finite deformations in finite elasticity and plasticity is presented. The element is based on an expansion of shape function derivatives using Taylor series and an extended set of orthogonality conditions that have to be satisfied for an hourglassing free EAS formulation. Such approach has not been applied so far in the context of large deformation three-dimensional problems. It leads to a surprisingly well-behaved locking and hourglassing free element formulation. Major advantage of the new element is its shear locking free performance in the limit of very thin elements, thus it is applicable to shell type problems. Crucial for the derivation of the residual and consistent tangent matrix of the element is the automation of the implementation by automatic code generation.     

SiC/MoSi_2复合材料1300℃氧化行为研究

采用扫描电镜和X射线衍射研究了不同SiC体积分数(30%～50%)的SiC/MoSi2复合材料的高温(1300℃)氧化性能,建立了SiC/MoSi2复合材料的高温氧化动力学模型,对SiC/MoSi2复合材料的高温氧化行为进行了动力学分析,研究了其高温氧化机理。结果表明,SiC/MoSi2复合材料在高温时具有优异的抗氧化性能,SiC/MoSi2复合材料的高温抗氧化能力好于纯MoSi2的;复合材料的高温抗氧化性随SiC体积分数的增加而降低。     

催化剂再生尾气中二氧化碳分析

介绍了一种定量分析气相氟化催化剂再生处理尾气中 (含氟化氢、氯化氢等酸性气体 )二氧化碳含量的化学方法 ,来判断催化剂再生进行的程度 ,从而决定催化剂再生处理的时间。此方法简洁、快速、实用、设备简单且不受尾气中腐蚀性气体的影响     

用一价盐浮选分离钠长石和钾长石

钠长石和钾长石（正长石或微斜长石）是长石矿石中的重要组成部分。它们通常约含3％－5％Na2O和K2O。尽管钠长石和钾长石的晶体结构和物理化学性质非常相近,但看起来浮选仍角是分离它们的唯一可行的方法。本研究用动电位测定、矿物溶解度测定,表面张力测定,吸附量测定和浮选试验等研究手段,寻找在一价盐作用下钠长石和钾长石胺法浮选的有效分选区间。研究结果表明,NaCl和KCl在某一特定浓度下,钠长石和钾长石浮选分离效果最好,钾长石和钠长石选择性浮选分离的作用机理在于同种离子（即所添加盐中离子与矿物晶格离子相同）吸附和不同种离子（即所 加盐类中离子与矿物晶格离子不相同）交换。     

用改性的羟肟酸类捕收剂浮选高岭土

反浮选是最有效地从高岭土中分离脱除带色杂质（主要是含钛和含铁矿物）方法之一。在高岭土浮选中,传统上采用塔尔油作捕收剂。这要求用金属离子（即Ca^2 ）活化那些带色杂质,以增大塔尔油在矿物上的吸附量。另一方面,业已证实,羟肟酸捕收剂的效果更好,它不需要活化。在本研究中,评估了一系列新型改性羟肟酸捕收剂对粘土矿物浮选性能的影响。原矿采自美国佐治亚洲。与标准的塔尔油捕收剂和工业上已应用的普通羟肟酸捕收剂（如Aero、Promoter-6493）相比,这些新型改性羟肟酸捕收剂具有更好的性能和浮选指标。