基于DLP 3D打印的高给药效率微针制备工艺

载药微针可以实现一次性快速药物递送,无需二次药物涂敷与输送过程,但其不佳的载药量与刺入率造成了给药效率差的问题。研发了一种基于数字光处理(DLP)3D打印技术的高给药效率微针(HDMN)制备工艺。通过在载药微针上构建锯齿状针体结构与阶梯状载药结构来提高载药微针的刺入率与载药量,进而提高给药效率。实验结果表明使用环氧丙烯酸酯(EA)打印微针时,当曝光时间为700 ms、打印层厚为30μm时,打印出的微针实际尺寸与理论尺寸平均误差最小为9.2%。利用旋涂法在微针表面交联聚乙二醇二丙烯酸酯(PEGDA)以改善微针生物相容性。显微镜观察发现,当交联层数为1层时,PEGDA均匀地覆盖在微针表面。石蜡膜穿刺实验结果表明,HDMN穿透了2层石蜡膜,而相同实验条件下的传统载药微针仅穿透了1层。药物释放实验结果表明,HDMN相对于传统载药微针在猪皮内留下的模拟药物浓度提升了61%。该研究为后续通过改善微针结构来优化微针性能研究提供了有益借鉴。

高效率微带线光导开关非线性特性的实验研究

本文报道了高效率微带线光导开关非线性输出特性的实验研究 ,给出了输出波形 ,并与普通微带线电路光导开关的输出进行了比较 ,指出了这种微带线电路光导开关非线性输出的高效率特性、双极特性及利用非线性光导开关研制新型高效率、高压。

微结构多通道混合器的混合性能研究

微通道混合器的微混合性能是快速反应体系(如聚合物纳米复合材料的制备)的关键影响因素之一。微混合效率是微通道混合器应用和优化的核心参数指标,吸引了大量的研究者关注。本工作设计了一种微结构多通道混合器,并利用光固化3D打印成型技术制造,该混合器具有强化混合和易于优化改进的优点。微结构多通道混合器的混合效率采用碘化物-碘酸盐平行竞争反应体系和计算流体动力学(CFD)结合的方法进行分析,并研究多通道混合腔体内部雷诺数(R_(e))对微混合效率的影响。分离指数(X_(S))被用来评价微混合效率。结果表明,X_(S)随着R_(e)的增加而减少,对于低R_(e)时腔室中心具有低湍动强度,当R_(e)达到4963时,最高湍动能的区域移动到腔室的中心,实现有效混合。实验值与模拟值变化趋势一致,证明入口流速对微混合性能起到关键的作用。这项研究表明,该混合器在提高微混合效率、制造方式等方面具有优势,有望在快速反应及强化混合过程中得到应用。

电致伸缩微位移器在机床刀具微进给系统的应用

随着电子技术、宇航、生物工程等学科的发展,对精密机械的精度要求越来越高,要求精密机械和检测设备具有亚微米甚至纳米精度。使微位移技术得到迅速发展,主要介绍了电致伸缩微位移器的原理和应用。

Sterilization Effect on Microorganisms by High Electrostatic Voltage

利用静电高压在室温条件下做了两种细菌和一种真菌(金黄色葡萄球菌,绿脓杆菌和白色念珠菌)的灭菌实验。实验中用了星形线和芒刺极两种电极结构,研究了这三种菌的存活率与电压、电晕功率和处理时间的关系。作者等也研究了正、负高压。正、负脉冲高压和交流高压对灭菌效果的影响。实验结果表明,适当选取条件,这三种菌完全可被电晕放电场杀死。静电灭菌是一种新方法,到目前为止,特别是对非液体物质的静电灭菌,尚未见报道。尽管这一技术还需进一步研究,但它为寻找新的灭菌途径提供了可能。

Cooperative Differential Game for Model Energy-Bandwidth Efficiency Tradeoff in the Internet of Things

Internet of Things （IoT） refers to an infrastructure which enables the forms of com- munication and collaboration between people and things, and between things themselves. In order to improve its performance, we present a tradeoff between bandwidth and energy con- sumption in the loT in this paper. A service providing model is built to find the relation- ship between bandwidth and energy consump- tion using a cooperative differential game mo- del. The game solution is gotten in the condi- tion of grand coalition, feedback Nash equili- brium and intermediate coalitions and an allo- cation policy is obtain by Shapley theory. The results are shown as follows. Firstly, the per- formance of IoT decreases with the increasing of bandwidth cost or with the decreasing of en- ergy cost; secondly, all the nodes in the IoT com- posing a grand coalition can save bandwidth and energy consumption; thirdly, when the fac- tors of bandwidth cost and energy cost are eq- ual, the obtained number of provided services is an optimised value which is the trade-off between energy and bandwidth consumption.

Root Zone Microbial Populations, Urease Activities, and Purification Efficiency for a Constructed Wetland

In order to investigate the effects of microorganisms and their urease activities in macrophytic root zones on pollutant removal, four small-scale plots (SSPs) of vertical/reverse-vertical flow wetlands were set up to determine: a) the relationship between the abundance of microorganisms in the root zones and water purification efficiency; and b) the relationship between urease activities in the root zones and pollutant removal in a constructed wetland system. Total numbers of the microbial population (bacteria, fungi, and actinomyces) along with urease activities in the macrophytic root zones were determined. In addition, the relationships between microbial populations and urease activities as well as the wastewater purification efficiencies of total phosphorus (TP), total Kjeldahl nitrogen (TKN), biochemical oxygen demand in 5 days (BOD5), and chemical oxygen demand (COD) were also analyzed. The results showed that there was a highly significant positive correlation (r = 0.9772, P ＜ 0.01) between the number of bacteria in the root zones and BOD5 removal efficiency and a significant negative correlation (r = -0.9092, P ＜ 0.05) between the number of fungi and the removal efficiency of TKN. Meanwhile, there was a significant positive correlation (r -- 0.8830, P ＜ 0.05) between urease activities in the root zones and the removal efficiency of TKN. Thus, during wastewater treatment in a constructed wetland system,microorganism and urease activities in the root zones were very important factors.

Effect of bath composition and pulse electrodeposition condition on characteristics and microhardness of cobalt coatings

Nanocrystalline cobalt coatings were produced from cobalt sulfate based electrolytes by using pulse current electrodeposition technique.The effects of bath composition and electrodeposition condition on current efficiency,morphology,structure and hardness of the coatings were investigated and the optimum deposition condition was determined.It was found that increment of cobalt sulfate concentration and sodium dodecyl sulfate(SDS)concentration in the bath had a negligible effect on microhardness of the coatings,while they were effective on electrodeposition current efficiency.Adding saccharin to electrodeposition bath decreased crystallite size of hexagonal close-packed(hcp)cobalt films and increased their microhardness without significant effect on current efficiency.Smoother and less defective coatings were also obtained from baths containing SDS and saccharin.The results revealed that both the current efficiency and microhardness were changed by variation of peak current density and duty cycle.Besides change of smooth morphology of the coatings to needle-shaped one,crystallite sizes and preferred orientation also varied with increasing the current density and duty cycle.

Numerical Simulation of the Scalar Mixing Characteristics in Three-dimensional Microchannels

Based on the transport phenomena theory, the passive mixing of water and ethanol in different threedimensional microchannels is simulated numerically. The average variance of water volume fraction is used to index the mixing efficiency in the cases with different Reynolds number and different fabricated mixers. The results show that the efficiency of liquid mixing is progressively dependent on the convective transport as the Reynolds number increases. The efficiency of serpentine microchannel decreases with the increasing Reynolds number in the laminar regime. Altering the aspect ratio of channel inlet section has no significant effect on the mixing efficiency. Increasing the area of channel inlet section will cause the decrease of the mixing efficiency. The mixing in serpentine channels is the most efficient among three different mixers because of the existence of second flow introduced by its special structure.

Effect of microbial inoculants on Albizia saman germination and seedling growth

Microbial Inoculants as Effective Microorganisms （EM） were applied to find out their effects on germination and seedling growth of Albizia saman in the nursery. The seedlings were grown in a mixture of sandy soils and cow dung （3：1） kept in polybags. The EM solution at different concentrations （0.1%, 0.5%, 1%, 2%, 5% and 10%） was incorporated before and after a week of sowing seeds. Germination and physical growth parameters, including shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total biomass increment over the control were measured. The nodulation status influenced by EM was also observed along with the estimation of chemical parameters like chlorophyll a, chlorophyll b and carotenoid. Both germination and the measured physical growth parameters were found significantly （P〈0.05） higher in seedlings treated with different concentrations of EM solution in comparison to the control. Maximum growth was found at 2% followed by 1% EM solution. Nodulation was higher at 0.1% concentration but it normally decreased with the increase of concentrations. Although there were a higher amount of pigments in leaves of the treated seedlings than of the control, the variations recorded with respect to chlorophyll a, b and carotenoid were not significantly higher in most of the treatments. Treated seedlings showed variable results along with the increment of EM applications and most of the parameters showed best results at the medium range of concentrations. The study indicates that the Microbial Inoculant （EM） technology might be useful to improve the growth of seedlings in the nursery. This also indicates that the associated beneficial organisms along with the polybag soils might be of value in improving the degraded soil or poor field soil for better nutrient and water uptake during the initial growth of transplanted seedlings.

Electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V controlled by elements segregation and phases distribution

The electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V were investigated through Tafel polarization,potentiostatic polarization and AC impedance measurements.The results show that the solution treatment−aging(STA)process aggravates the element micro-segregation compared to the annealing process,leading to varied Al and V contents of the phases from different samples.It is proven that either Al-rich or V-rich condition can highly affect the electrochemical dissolution behaviors due to thermodynamical instability caused by element segregation.The dissolution rate in the metastable passivation process is controlled by the stability of the produced film that is affected by phases distribution,especially the difficult-to-dissolve phase.And then,the dissolution rate of the phases in the transpassivation region is consistent with the rank in the activation process because the dense film is not capable of being produced.Compared to the annealed sample,the higher dissolution rate of the STA sample is beneficial to the electrochemical machining(ECM)of Ti6Al4V.

Micromixing efficiency in a T-shaped confined impinging jet reactor

Confined impinging jet reactor(CIJR)offers advantages for chemical rapid processes and has become an important new reactor used in the chemical industry.The micromixing efficiency in a T-shaped CIJR for two tubes of inner diameter of 3 mm was studied by using a parallel competing iodide–iodate reaction as the working system.In this work,the effects of different operating conditions,such as impinging velocity and acid concentration,on segregation index were investigated.In addition,the effects of the inner nozzles diameter and the distance L between the jet axis and the top wall of the mixing chamber on the micromixing efficiency were also considered.It is concluded that the best range of L in this CIJR is 6.5–12.5 mm.Based on the incorporation model,the estimated minimum micromixing time tmof CIJR approximately equals to 2×10-4s.These experimental results indicate clearly that CIJR possesses a much better micromixing performance compared with the conventional stirred tank(micromixing time of 2×10-3to 2×10-2s).Hence,it can be envisioned that CIJR has more promising applications in various industrial processes.

Investigation of compaction and sintering behavior of SiC powder after ultra-fine treatment

Silicon carbide ceramics were prepared with SiC powder treated by the fluidized bed opposed jet mill as raw materials, and the effects of the ultra-fine treatment mechanism on the compaction and sintering behavior of SiC ceramics were investigated. The results showed that the compacts had higher density and microstructure homogeneity when the sintering temperature of the compact was decreased; and that the surface microstructure, densification and mechanical properties of the sintered body could be ameliorated obviously.

Influence of CsNO_3 as electrolyte additive on electrochemical property of lithium anode in rechargeable battery

Lithium metal is one of the most promising anode materials for rechargeable battery with high energy density,but its practical use is still hindered by two main problems,namely,lithium dendrite growth and low Coulombic efficiency.To address the issues,cesium nitrate(CsNO3)is selected as the additive to modify the electrolyte for lithium secondary battery.Here we report electrochemical performance of lithium secondary battery with different concentration of CsNO3 as electrolyte additive.The study result demonstrates that Coulombic efficiency of Li–Cu cells and the lifetime of symmetric lithium cells contained CsNO3 additive are improved greatly.Li–Cu cell with 0.05 mol/L CsNO3 and 0.15 mol/L LiNO3 as electrolyte additive presents the best electrochemical performance,having the highest Coulombic efficiency of around 97%and the lowest interfacial resistance.With increasing the concentration of CsNO3 as electrolyte additive,the electrochemical performance of cells becomes poor.Meanwhile,the morphology of lithium deposited films with CsNO3-modified electrolyte become smoother and more uniform compared with the basic electrolyte.

Numerical investigations on effects of bluff body in flat plate micro thermo photovoltaic combustor with sudden expansion

In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased.

The Qualitative Analysis of a Solution of a Series Maintenance System with Two Components

In this paper, firstly we study the series ma intenance system with two components, obtain its exsistence and uniqueness of a dynamic state nonnegative solution by strongly continuous semigroups of operator s theory. Then we prove that 0 is the eigenvalue of the system’s host operators, a nd finally we study the eigenvector of the eigenvalue 0.

Application of micro/nanoscale thermal radiation to thermophotovoltaic system

Thermophotovoltaic （TPV） system has been regarded as one promising means to alleviate current energy demand because it can directly generate electricity from radiation heat via photons. However, the presently available TPV systems suffer from low conversion efficiency and low throughput. A viable solution to increase their efficiency is to apply micro/nanoscale radiation principles in the design of different components to utilize the characteristics ~f thermal radiation at small distances and in microstructures. Several critical issues are reviewed, such as photovoltaic effect, quantum efficiency and efficiency of TPV system. Emphasis is given to the development of wavelength-selective emitters and filters and the aspects of micro/nanoscale heat transfer. Recent progress, along with the challenges and opportunities for future development of TPV systems are also outlined.

An Enhanced Spectrum Resource Allocation Algorithm in Hetnets

Efficient spectrum resource allocation in wireless heterogeneous networks is important for improving the system throughput and guaranteeing the user's Quality-of-Service(QoS).In this paper,we propose an enhanced algorithm for spectrum resource allocation in heterogeneous networks.First,the bandwidth of each user is determined by the user's rate demand and the channel state.Second,graph theory is enhanced and used to improve the spectrum efficiency.Third,spectrum resource is dynamically split between macrocell and femtocells with the changes of users' conditions.Our simulation results show that the proposed algorithm improves the system throughput significantly and also guarantees the fairness for the users.

Using Magnetic Technique to Increase Efficiency of Organic Pollutants Biodegradation in Wastewater

The intensity of Magnetic field by 200, 300 and 400 gaos were selective to study their impacts on bacteria Bacillus, Pseudomonas and yeasts Candida dubliniensis, Candida glabrata, lssatchenkia orientalis and Rhodotorula mucilaginosa growth and to reduce organic pollutants in wastewater by COD, TOC, TN and TP in concentrations of 180, 75, 52 and 84 ppm in pH 7.6 and treatment periods of 2, 4, 6 and 18 h in batch system. Results showed that magnetic field 300 gaos had higher ability to increase bacterial and yeasts growth by 400-600% in 18 h and reduced COD, TOC, TN and TP by 88, 85, 90 and 98.5% in same period treatment. While, the intensity of magnetic field 200 and 400 gaos have no effect on microorganisms growth and reducing organic pollutants. This study is first record for showing and explaining the positive effective of magnetic field on microorganisms growth.

Effect of Manure on Distribntion of Micronutrients in Rhizosphere of Wheat

A rhizobox system was used to determine the distribution of micronutrients (Fe, Mn, Cu and Zn) acrossthe rhmosphere of wheat (Triticum aestivum). The available contents of Fe and Mn in the rhizosphere wereraised by addition of manure or chemical fertilizer combined with manure, but those of Cu and Zn werehardly affected, which might be an important reason why manure addition could improve the Fe and Mnnutrition status of plants. Several possible mechanisms for the increase of the availabilities of Fe and Mn inthe rhizosphere due to manuring are discussed as well.