Direct-current nanogenerator driven by ultrasonic waves

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.     

Giant piezoelectricity on Si for hyperactive MEMS

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.     

Mechanical writing of ferroelectric polarization

Ferroelectric materials are characterized by a permanent electric dipole that can be reversed through the application of an external voltage, but a strong intrinsic coupling between polarization and deformation also causes all ferroelectrics to be piezoelectric, leading to applications in sensors and high-displacement actuators. A less explored property is flexoelectricity, the coupling between polarization and a strain gradient. We demonstrate that the stress gradient generated by the tip of an atomic force microscope can mechanically switch the polarization in the nanoscale volume of a ferroelectric film. Pure mechanical force can therefore be used as a dynamic tool for polarization control and may enable applications in which memory bits are written mechanically and read electrically.     

Laser scribing of high-performance and flexible graphene-based electrochemical capacitors

Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.     

不同采摘期甘薯茎尖中矿质元素分析

[目的]比较不同采摘期甘薯(Dioscorea esculenta)茎尖中的矿质元素含量,为甘薯茎尖的开发利用提供可靠的理论依据。[方法]甘薯品种分别为一窝红、红腿、卢选1号和胜利100号。采摘期为甘薯的茂盛和成熟阶段,具体日期分别为2011年8月15、24和9月4、15、26日。测定矿质元素分别为铜、铁、钙、锌、镁和锰。[结果]不同采摘期的甘薯茎尖矿质元素含量不同。整体上,4个甘薯品种的矿质元素含量较丰富,其中,除铁、锌、锰外,胜利100号的矿质元素含量均最高。[结论]甘薯茎尖具有较高的营养价值,可进行推广和综合开发。     

Single-crystal nanorings formed by epitaxial self-coiling of polar nanobelts

Freestanding single-crystal complete nanorings of zinc oxide were formed via a spontaneous self-coiling process during the growth of polar nanobelts. The nanoring appeared to be initiated by circular folding of a nanobelt, caused by long-range electrostatic interaction. Coaxial and uniradial loop-by-loop winding of the nanobelt formed a complete ring. Short-range chemical bonding among the loops resulted in a single-crystal structure. The self-coiling is likely to be driven by minimizing the energy contributed by polar charges, surface area, and elastic deformation. Zinc oxide nanorings formed by self-coiling of nanobelts may be useful for investigating polar surface-induced growth processes, fundamental physics phenomena, and nanoscale devices.     

高锌日粮对断奶仔猪血清锌和粪便排泄锌含量的影响

选用80头"杜洛克×长白×约克夏"三元杂交断奶仔猪,按公母各半、体重相近的原则随机分为4个处理组(即Ⅰ、Ⅱ、Ⅲ和Ⅳ组),每组20头仔猪,分别饲喂在相同基础日粮中添加100 mg/kg锌(氧化锌,Ⅰ组)、1 000 mg/kg锌(氧化锌,Ⅱ组)、2 000 mg/kg锌(氧化锌,Ⅲ组)、3 000 mg/kg锌(氧化锌,Ⅳ组)的饲料,试验期6周.在试验的第14、28、42 d分别从各组随机采集6头仔猪的血液样本,进行血清锌的检测;试验的第1～7 d每日收集各组6头仔猪的粪便,以后每周收集1次,测定粪便中锌的含量.结果表明:高锌日粮能显著增加断奶仔猪血清的锌浓度;也可使断奶仔猪粪便中锌排泄浓度显著增加,易造成环境污染.     

不同水基防腐剂处理木材的表面自由能

该研究中测定了蒸馏水、二碘甲烷、甲酰胺和甘油等4种参照液体在不同水基防腐处理（包括铬化砷酸铜CCA以及另外两种商品名为NW和NS的处理）后的木材表面所形成的接触角，并根据酸碱作用理论计算得到其表面自由能及其两个分量——Lifshiz van der Waals（LW）分量和酸碱作用（AB）分量.结果表明，NW和CCA处理使木材表面的疏水性有所增加，而NS处理由于早材的水分渗透速率加快总体表现为亲水性增加.利用蒸馏水、二碘甲烷、甲酰胺这3种参照液体计算得到的未处理早材、未处理晚材、CCA处理早材、CCA处理晚材、NW处理早材、NW处理晚材、NS处理早材和NS处理晚材的表面自由能分别为43.1、44.5、43.4、45.1、49.4、40.6、46.0和40.9 mJ/m[[sup]]2[[/sup]].由此可见，CCA处理材的表面自由能接近于未处理材，而经过NW和NS处理后，早材和晚材的表面能都有一定程度的变化，但对于木材整体来说表面自由能仍接近于未处理材.      

基于抗菌活性的氧化锌粒子的制备及其性能研究

为制备具有抗菌活性的氧化锌粒子,以硝酸锌和氢氧化钠为原料,采取水热法制备得到纳米氧化锌,并研究其抗菌性能.采用粒度分析、红外光谱分析、扫描电镜分析和热重分析手段,系统研究了pH、反应温度、反应时间、氢氧化钠浓度对纳米氧化锌粒径的影响,获得了制备纳米氧化锌的最佳条件.研究结果表明,当氢氧化钠浓度为0.2 mol/L、pH...     

Carbon-based supercapacitors produced by activation of graphene

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp(2)-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.     

不同锌源及其水平对桃源鸡血清抗氧化指标的影响

[目的]探究不同锌源、锌水平对桃源鸡血清抗氧化指标的影响。[方法]选用420只桃源鸡,采用2因素3水平完全随机试验设计,2种锌源分别为羟基蛋氨酸锌、氧化锌,添加水平分别为30、60、90mg/kg,将桃源鸡随机分为7个处理组,每个处理组设3个重复,每个重复20只鸡,分3～48、48～93日龄2个阶段饲养,每个试验期结束时进行桃源鸡血清抗氧化指标测定试验。[结果]试验前期,锌的添加及不同添加水平时桃源鸡血清SOD活性、血清MDA含量在0.05水平上差异不显著,随着锌水平的添加同一锌源内血清SOD活性呈上升趋势;试验后期,锌源添加水平为90 mg/kg时血清SOD活性在0.05水平上显著高于基础日粮组,氧化锌添加水平为90mg/kg时血清MDA含量在0.05水平上显著低于基础组,不同锌源、锌水平间血清SOD活性差异不显著,血清MDA含量呈下降趋势。[结论]锌源的添加能提高桃源鸡血清中SOD酶活性,降低血清中MDA含量,减轻自由基的损伤,从而提高机体的抗氧化能力,在高温条件下更加明显;但羟基蛋氨酸锌和氧化锌两者间对桃源鸡血清中SOD活性和MDA含量的影响变化规律还有待进一步研究。     

Fuel-powered artificial muscles

Artificial muscles and electric motors found in autonomous robots and prosthetic limbs are typically battery-powered, which severely restricts the duration of their performance and can necessitate long inactivity during battery recharge. To help solve these problems, we demonstrated two types of artificial muscles that convert the chemical energy of high-energy-density fuels to mechanical energy. The first type stores electrical charge and uses changes in stored charge for mechanical actuation. In contrast with electrically powered electrochemical muscles, only half of the actuator cycle is electrochemical. The second type of fuel-powered muscle provides a demonstrated actuator stroke and power density comparable to those of natural skeletal muscle and generated stresses that are over a hundred times higher.     

双稳态压电悬臂梁发电系统的动力学分析

双稳态压电悬臂梁发电系统由于其自身在发电效率方面的优越性,受到了科研人员的广泛关注。为了研究该系统的相关特性,首先建立了等效的周期激励和随机激励作用下双稳态压电悬臂梁俘能系统的数学模型;其次通过龙格-库塔法,得出系统在单势阱和双势阱内振动响应的振幅、输出功率和电压等计算结果;并分析了双稳态系统工作过程中出现的随机共振现象,得到它们的变化规律及特性;通过将这些数值计算结果进行分类对比分析,显示了双稳态压电俘能系统在激励响应幅值、频率响应范围和输出功率等方面的优越性。以上研究结果为优化双稳态压电悬臂梁俘能器的设计和应用提供了理论依据。     

Induction of nitric oxide-dependent apoptosis in motor neurons by zinc-deficient superoxide dismutase

Mutations in copper, zinc superoxide dismutase (SOD) have been implicated in the selective death of motor neurons in 2 percent of amyotrophic lateral sclerosis (ALS) patients. The loss of zinc from either wild-type or ALS-mutant SODs was sufficient to induce apoptosis in cultured motor neurons. Toxicity required that copper be bound to SOD and depended on endogenous production of nitric oxide. When replete with zinc, neither ALS-mutant nor wild-type copper, zinc SODs were toxic, and both protected motor neurons from trophic factor withdrawal. Thus, zinc-deficient SOD may participate in both sporadic and familial ALS by an oxidative mechanism involving nitric oxide.     

Energy generation for an ad hoc wireless sensor network-based monitoring system using animal head movement

The supply of energy to electronics is an imperative constraining factor to be considered during the design process of mobile ad hoc wireless sensor networks (MANETs). This influence is especially important when the MANET is deployed unattended or the wireless modules within the MANET are not easily accessible. Therefore, exploring novel sources of energy generation rather than operating electronics only on limited power supplies such as batteries is a major challenge. Monitoring free-ranging animal behavior is an application in which the entities (animals) within the MANET are not readily accessible; however, animal movement can be potentially used to generate energy. In this study, the head movements of individual sheep in a flock during grazing were monitored in order to investigate the amount of energy that can be generated by these movements. By applying the Lagrange-d’Alembert Principle to this problem, the equations of motion from each neck-mounted sensor as well as the amount of mechanical energy generated per time instant (each second) during upward and downward head movements were calculated. This resulted in the production of 857 mW and 1660 mW during the downward and upward movements, respectively. Furthermore, the energy consumption of each wireless node within the MANET was estimated to be 117.8 mW per second. Conversion of energy from mechanical to electrical requires miniature electromechanical generators that can currently provide between 25% and 50% conversion efficiency. Even using the worst conversion efficiency (25%), a minimum of 214 ± 25 mW of electrical energy per second could be generated. This amount exceeds the energy consumed by the wireless sensors that can be used to gather parameters describing animal behavior such as neck and head movement. This study suggests that the amount of energy generated by the vertical neck-head movement of sheep during grazing can be converted to useful electrical power adequate to provide power for operation of wireless sensor nodes on a continuous basis within a MANET-based animal behavior monitoring system.     

表面活性剂对纳米氧化锌合成及分散性的影响

在比较了各种合成方法后，我们采用固相合成法来制备纳米氧化锌，并对其提出了改进．通过在固相反应过程中加入表面活性剂对纳米氧化锌进行了表面改性，制备出了粒径更小、分散性更好的氧化锌．用X-射线粉末衍射仪、扫描电镜表征产物的结构和形貌，用分光光度计研究其分散性．结果表明，改性后产物的分散性得到了显的改善，较之未改性样品，其吸光度均有不同程度的增加，且在不同极性溶剂中的分散性随表面活性剂种类和用量的不同而不同．     

植物细胞的皂苷反应研究进展

天然皂苷具有广泛的药理学性质,细胞毒性和皂苷化学预防的作用由一个信号传导途径来调节,这在动物细胞中的作用十分显著。一氧化氮、锌和金属硫蛋白是机体内重要的生物活性因子,它们之间存在着相互作用,一氧化氮能够与金属硫蛋白形成稳定的化合物,引起蛋白质的构象变化和锌的选择性释放,同时参与细胞氧化应激反应,金属硫蛋白除了在重金属解毒上的作用外,还具有抗氧化作用,锌和一氧化氮可以调控金属硫蛋白的表达。植物细胞和动物细胞在皂苷反应方面有共同特点,但植物细胞对皂苷和相关信号传导通路的反应很少,机制也不明确,有待进一步研究。就一氧化氮、金属硫蛋白和锌在植物细胞皂苷反应中的作用加以论述。     

Carbon nanotube quantum resistors

The conductance of multiwalled carbon nanotubes (MWNTs) was found to be quantized. The experimental method involved measuring the conductance of nanotubes by replacing the tip of a scanning probe microscope with a nanotube fiber, which could be lowered into a liquid metal to establish a gentle electrical contact with a nanotube at the tip of the fiber. The conductance of arc-produced MWNTs is one unit of the conductance quantum G0 = 2e2/h = (12.9 kilohms)-1. The nanotubes conduct current ballistically and do not dissipate heat. The nanotubes, which are typically 15 nanometers wide and 4 micrometers long, are several orders of magnitude greater in size and stability than other typical room-temperature quantum conductors. Extremely high stable current densities, J > 10(7) amperes per square centimeter, have been attained.     

纳米氧化锌对肉鸡免疫性能及组织锌含量的影响

本试验研究了纳米氧化锌对肉鸡免疫性能及组织锌含量的影响。选用1日龄AA肉仔鸡192只,随机分为4组,每组设4个重复,每个重复12只鸡。在玉米-豆粕型日粮基础上添加纳米氧化锌0mg/kg(对照)、40mg/kg、80mg/kg、120mg/kg,全期分为0~21日龄、22~42日龄两个饲养阶段。按常规免疫鸡群新城疫(ND),每隔7d翼下静脉采血(8只/组)用HA-HI法测定ND的抗体滴度;并于21日龄和42日龄时各宰杀48只体重接近全群平均体重的试验鸡(3只/重复),取其胸腺、脾脏和法氏囊分别称重,同时采集肝脏、胫骨及血清样品,用于测定血清、肝脏、胫骨锌含量和血清碱性磷酸酶活性,取抗凝血(4只/组),MTT法测定淋巴细胞转化率。结果表明:添加40~80mg/kg水平纳米氧化锌,显著提高了肉鸡的免疫能力(P<0.05),提高了外周血T淋巴细胞转化率;添加40mg/kg纳米氧化锌可显著提高肉鸡肝脏和胫骨中锌含量和血清碱性磷酸酶活性(P<0.05)。因此,纳米氧化锌在40~80mg/kg添加水平时能较显著的增强肉鸡的免疫能力,增加组织中锌含量。     

64通道压电超声管道腐蚀检测原型机研制及试验

基于压电超声管道腐蚀检测技术,研制了一套适用于油、水等液体长输高压管道的64通道压电超声腐蚀检测原型机,并开展原型机整机静态和动态测试工作。验证结果表明:由电子系统、机械载体、传感器支撑结构、里程信息采集单元、超低频发射及接收单元组成的跟踪定位系统能够满足设计指标和性能需求,可以获得高质量的检测数据。64通道压电超声管道腐蚀检测原型机的研制与测试,对于提高中国压电超声管道腐蚀检测技术水平,促进管道检测技术手段的多样化具有重要的推动作用。