压电非接触式点胶阀的设计与实验

近年来,点胶系统的使用日益广泛,各类精密液体分配系统对该技术需求旺盛。该文提出了一种由叠层压电陶瓷驱动的非接触式点胶阀,该阀由两个相同的叠层压电陶瓷驱动,通过位移放大机构,改变位移的输出方向,并将力传递给阀杆,最终实现喷射。利用FLUENT软件模拟了点胶过程,分析了流体喷射机理,通过实验研究了阀杆抬起时间、气压、流体粘度等喷射参数对于点胶量的影响,实验结果与仿真结果吻合。实验使用直径为0.35mm的喷嘴、喷射液体为甘油时,可以获得平均直径为0.53mm的液滴,其一致性误差小于6%。     

超声波马达定子部分的粘接工艺

压电陶瓷层与金属层间的粘接技术是决定超声波成在能否正常工作的关键性技术，胶层中微观的剪切力是使金属怪产生微波柔性变形，造成输出力的直接原因。粘拉 的强度以及在剪切力作用下的稳定度直接影响到超声波马达长时间工作的稳定性和使用寿命。     

聚乙烯醇生物降解的影响因素

研究了水溶性高分子聚乙烯醇(PVA)的生物降解性及其影响因素.结果表明,PVA的分子量、结晶度对其生物降解性具有决定作用.通过等离子体作用或氧化处理,可在PVA分子上引入＞C=O、-O=C-O、-COOH等基团,从而提高PVA的生物降解性和降解速率.     

Fe78Co2Zr8Nb2B10-xGex（x=1,2,3）合金的晶化过程和磁性能研究

采用单辊快淬法制备Fe78Co2Zr8Nb2B10-xGex(x=1,2,3)系非晶合金,在不同热处理条件下对两种合金进行热处理。利用X射线衍射仪(XRD)、透射电镜(TEM)和振动样品磁强计(VSM)等测试手段对合金的微观结构和磁性能进行研究。研究结果表明,3种合金的晶化过程相似:非晶→非晶+α-Fe(Co)→α-Fe(Co)+Fe3Zr+Fe2B。3种合金的比饱和磁化强度(Ms)大体上随退火温度的升高而增大;3种合金的矫顽力(Hc)随退火温度的升高均呈现先增加、后降低、再增加的复杂变化趋势。     

Preparation and electromagnetic characteristics of silica coated Fe–Ni–Mo alloy flakes

The Fe–Ni–Mo alloy flakes were firstly prepared from water atomized powders. Subsequently, by a facile sol–gel technique using tetraethylorthosilicate (Si(OC₂H₅)₄) as a precursor, we successfully synthesized silica coated Fe–Ni–Mo alloy flakes. These products were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Furthermore, their electromagnetic parameters, complex permittivity and complex permeability within 2–12 GHz were measured. The results show that both and values of the silica coated flakes substantially decrease with the increase of coating times. Meanwhile, the μ′ values of silica coated samples are larger than those of the as-milled sample at the high frequencies. However, the maximum μ′ exhibits a decline while resonance frequency shifts to high values with the increase of coating times. The calculated reflection loss (RL) curve reveals that a proper thickness of coating can redound to improve the absorbing performances of silica coated Fe–Ni–Mo alloy flakes in high frequency range.     

一种新型空气源热泵除霜方式的实验研究

提出了一种新型空气源热泵除霜方式,其基本原理是在热汽旁通除霜循环的基础上将室外换热器分为前后两排,中间用毛细管节流,前后排换热管在除霜过程中分别作为蒸发器和冷凝器,利用四通阀换向分别对其进行除霜.对新循环除霜性能进行了实验研究,并与逆循环除霜方式进行了比较.实验结果表明,新型分组节流除霜方式合理地利用了除霜能量,因此除霜时间及除霜损失小于传统逆循环除霜方式.而且在除霜过程中不从室内吸收热量,对其温度波动影响较小.在除霜过程中,新除霜方式的四通阀换向次数与逆循环除霜方式相同,但系统压力的波动幅度远远小于逆循环除霜方式,因此对系统的机械冲击要小得多.     

Sialic acid‐conjugated PLGA nanoparticles enhance the protective effect of lycopene in chemotherapeutic drug‐induced kidney injury

Lycopene (LYC) is known to protect cells from oxidative damage caused by free radicals in human tissues. In the present study, the authors designed a LYC‐loaded sialic acid (SA)‐conjugated poly(D,L‐lactide‐co‐glycolide) (PLGA) nanoparticle (LYC‐NP) to enhance the therapeutic efficacy of LYC in acute kidney injury. The characteristics of the LYC‐NPs were defined according to particle size, morphology, and in vitro drug release. The LYC‐NPs exhibited a controlled release of LYC over 48 h. Confocal laser scanning microscopy clearly highlighted the targeting potential of SA. Enhanced green fluorescence was observed for the LYC‐NPs in H₂ O₂ ‐treated human umbilical vein endothelial cells, indicating enhanced internalisation of NPs. The LYC‐NPs showed significantly greater cell viability than H₂ O₂ ‐treated cells. In addition, the LYC‐NPs remarkably reduced proinflammatory cytokine levels, attributable mainly to the increased cellular internalisation of the SA‐based carrier delivery system. Furthermore, protein levels of caspase‐3 and ‐9 were significantly down‐regulated after treatment with the LYC‐NPs. Overall, they have demonstrated that SA‐conjugated PLGA‐NPs containing LYC could be used to treat kidney injury.Inspec keywords: fluorescence, biomedical materials, biological tissues, cellular biophysics, drugs, proteins, molecular biophysics, injuries, drug delivery systems, kidney, nanomedicine, biochemistry, optical microscopy, nanoparticles, nanofabrication, cancer, toxicology, blood vessels, particle sizeOther keywords: sialic acid‐conjugated PLGA nanoparticles, chemotherapeutic drug‐induced kidney injury, LYC‐NP, LYC‐loaded sialic acid‐conjugated poly(D,L‐lactide‐co‐glycolide) nanoparticle, SA‐conjugated PLGA‐NP, protective effect, lycopene, human tissues, particle size, in vitro drug release, confocal laser scanning microscopy, green fluorescence, human umbilical vein endothelial cells, cell viability, proinflammatory cytokine levels, cellular internalisation, SA‐based carrier delivery system, time 48.0 hour     

山东、河南烟草病毒病发生种类、发病规律研究

受干旱和异常气候的影响,目前逐年加重的烟草病毒病已成为北方地区烟草生产的制约因素。为进一步研究有效防治病毒病的途径,于2000~2002年对河南、山东主产烟区烟草病毒病的发病情况进行了详细调查和病毒种类检测。结果表明,PVY、CMV是危害该地区的主要病毒种类,TRSV近几年已经成为该地区又一重要病毒。结合烟草病毒病的发生规律,对烟草病毒病的防治对策及生产中急需解决的问题作了探讨。      

g-C3N4/CQDs光催化材料的制备及性能

采用高温热解法制备了石墨相氮化碳(g-C_3N_4),将其与碳量子点(CQDs)进行水热复合,得到g-C_3N_4/CQDs复合光催化剂。采用SEM、TEM、FTIR、XRD、UV-Vis/DRS、XPS、N2吸附-脱附等温线手段对制备的复合光催化剂进行了表征,以罗丹明B(Rh B)为模拟污染物,考察了g-C_3N_4/CQDs的可见光催化活性及稳定性。结果表明:与g-C_3N_4相比,g-C_3N_4/CQDs对可见光吸收强度增加,同时其吸收波长向可见光区发生红移;当CQDs含量为1.5%(以g-C_3N_4质量为基准)时,所得g-C_3N_4/CQDs光催化材料的催化活性最佳,其对Rh B的光催化降解率是54.5%,是g-C_3N_4光催化降解率的1.38倍,化学反应动力学拟合相关系数R2=0.9982。且g-C_3N_4/CQDs循环使用3次后,其催化降解率仍保持在50%以上。光催化机理研究表明,空穴(h+)、超氧阴离子自由基(·O2–)、过氧化氢分子(H2O2)和羟基自由基(·OH)都是光催化过程中的主要活性物种,四者氧化作用大小依次为:h+·O2– H2O2·OH。     

基于Cosserat理论的柱状节理岩体本构模型

柱状节理岩体复杂的各向异性对相关工程设计及施工提出了挑战,准确掌握其各向异性力学参数对降低工程风险十分重要。基于Cosserat理论和Goodman当量叠加原理,首先建立了四棱柱、五棱柱、六棱柱柱状节理岩体二维本构模型。通过引入应力集中系数,将本构关系扩展至三维空间。针对白鹤滩水电站柱状节理岩体,采用3种模型分别计算了工程常数取值,并分析了3种模型计算结果与工程经验取值差异,比较了3种模型各向异性特征。结果表明,3种模型计算值与经验公式估算结果及现场原位承压板试验结果相近,四棱柱、五棱柱、六棱柱柱状节理岩体模型的弹性参数变化曲线分别反映出各模型正交各向异性、准横观各向同性、横观各向同性的各向异性特征。