制备超细微粒的超临界流体沉淀技术新进展

超临界流体沉淀(SFP)技术以其特有的优点成为具有广阔应用前景的超细微粒制备方法.本文着重综述了气体饱和溶液沉析(PGSS)、超临界辅助雾化(SAA)和膨胀液体有机溶液减压(DELOS)等最新SFP技术的原理、特点及相关的应用,指出了目前SFP技术存在的问题及今后的研究方向.     

超临界CO_2技术在高分子科学中应用的研究进展

本文综述了超临界CO_2的特殊性质，如溶解能力和溶胀能力随压力急剧变化等，总结了它在高分子科学中的应用，包括以它为介质的溶液聚合、乳液聚合、分散聚合、沉淀聚合反应及RESS技术、分级技术等．     

药用微胶囊的制备

微胶囊技术是21世纪重点研究开发的高新技术之一,用途广泛。本文综述了微胶囊的制备原理及方法,着重阐述了采用超临界二氧化碳技术和溶剂蒸发法制备药物微胶囊的最新研究进展,介绍了超临界流体快速膨胀(RESS)法、超临界流体抗溶剂(SAS)法和气体饱和溶液微粒制备(PGSS)法的特点,总结了溶剂蒸发法制备微胶囊的原理和溶剂蒸发法制备药物微胶囊的工艺研究现状,分析了药物微胶囊的表征方法及性能,并对今后微胶囊技术的发展作了展望。     

向日葵盘果胶对碳钢的缓蚀性能研究

以向日葵盘为原料,利用纤维素酶制备果胶(SFP)。采用静态失重、极化曲线和交流阻抗技术研究SFP在1mol/L HCl及0.5mol/L H_2SO_4溶液中对碳钢的缓蚀性能,并探讨其在碳钢表面的吸附机理。结果表明,缓蚀效率随SFP浓度增大而增大,随温度升高而降低。在HCl和H_2SO_4溶液中,SFP的吸附方式分别服从Langmuir和Temkin等温式,属于物理吸附;极化曲线测试显示SFP是一种混合型缓蚀剂。本文的研究表明,向日葵盘果胶是碳钢的绿色高效缓蚀剂,且在HCl溶液中的缓蚀性能优于在H_2SO_4溶液中。     

电子显微镜下的纳米世界

以高中阶段知识为基础,简述了扫描电子显微镜、透射电子显微镜等电镜技术的发展和基本原理,并以实际应用案例介绍了电镜技术在纳米科学领域的应用,最后给出了电镜技术的未来发展前景。     

分子模拟在生物传感器研究中的应用

分子模拟通常包括以量子力学和经典力学为基础的两部分,依赖于计算机的大量运算能力。其飞速发展渗透和推动了包括工程类学科以及化学、生物学等许多学科的发展。生物传感器是一个多学科交叉的研究热点.本文以计算机模拟研究中与生物传感器有关的内容作为切入点,简要介绍了计算机模拟技术的原理及生物敏感分子吸附和设计筛选、特异性生物反应过程的原理和优化等方面的研究成果,为应用计算机技术推动生物传感器的开发和应用提供了一些新的思路。     

印制电路中电镀铜技术研究及应用

电镀铜技术是制造印制电路板、封装载板等电子互连器件的核心技术.本文介绍了印制电路中电镀铜技术及其发展概况,主要总结了电子科技大学印制电路与印制电子团队在印制电路电镀铜技术基础研究和产业化应用等方面的工作.首先,以三次电流分布理论为基础,采用多物理场耦合方法构建阴极表面轮廓线随时间变化的镀层生长过程模型.该模型描述了铜沉...     

食源性致病菌快速检测方法研究进展

食源性致病菌污染是导致食品安全问题的重要因素,食源性致病菌的检测已成为近年来研究的热点.以免疫分析、分子生物学、生物传感器、代谢组学、核酸适配体等技术为基础的快速检测方法发展迅速,已成为检测食源性致病菌的主要方法.该文结合近年来各种快速检测方法的相关研究进展,介绍了以上述技术为基础的快速检测食源性致病菌的方法,并讨论了...     

智能涂料制备方法探索与应用

智能涂料是近几年在新型特种功能涂料基础上发展起来的.本文主要对其制备方法、类别及应用进行了详细论述.智能涂料的制备可以从聚合物膜、颜料及制作工艺等方面入手,其中创造具有"开关"性质且依赖于外部环境的刺激/响应聚合物膜的设计最为重要,它关系到膜的形成和膜表面性质,是涂料智能化的关键所在.在合成方法上,活性/可控自由基聚合技术、表面接枝技术和层层自组装工艺等已经应用于智能聚合物膜的制备;另外,纳米技术应用于涂料,也是智能涂料另一制备方法,因其某些超强性能而被视为智能涂料的初级阶段.目前,整个智能涂料的发展还基本处于以纳米技术为基础的初级阶段,其中进展较大的品种有:自清洁、抗菌、防腐、隐身、发光、磁性等对光、电、磁、温、湿、压敏感的涂料,而以智能聚合物膜为基础的高层次智能涂料还基本处于研究开发阶段.     

MXenes材料的光学特性及相关研究进展

过渡金属碳化物、 氮化物或碳氮化物(MXenes)具有丰富的元素组成和结构可调性, 显示出丰富的物理化学性质和巨大的应用潜力. 本文以此类材料的基本光学特性为基础, 从光子发射、 透明导电及储能、 非线性光学、 表面等离激元及拉曼增强、 光热转化、 光催化及光响应等光学相关领域展开分析和综述. 并对此二维材料相关应用的未来发展及机遇作了简单评述, 以期为进一步的研究提供参考.     

Fabrication of Micron Level Particles of Amoxicillin by Rapid Expansion of Supercritical Solution

In this study, the rapid expansion of supercritical solution (RESS) process was used to precipitate fine solid particles of amoxiccilin where supercritical carbon dioxide was used as a solvent. The process has been done by changing the RESS parameters, including extraction pressure (150–210 bar), extraction temperature (313–333 K), nozzle length (2–15 mm), effective nozzle diameter (450–1700 µm), and spraying distance (1–10 cm), to investigate the effect of these parameters on the size and morphology of the precipitated amoxicillin particles. The characterization (size and morphology) of the particles was examined using scanning electron microscopy (SEM). Based on the different experimental conditions, the mean particle size of the fabricated particles were between 1.08 and 5.72 µm, while the intact particles of amoxicillin were about 41.46 µm. Also, no regular changes in the morphology of the processed particles were observed.     

Solubility and micronisation of phenacetin in supercritical carbon dioxide

The rapid expansion of a supercritical solution (RESS) process represents an attractive prospect for producing sub-micron and nano-particles of medical compounds with low solubility. The solubility of phenacetin in supercritical carbon dioxide was measured by the analytical-isothermal method at pressures ranging from 9.0 MPa to 30.0 MPa and temperatures ranging from 308.0 K to 328.0 K. The results show that the mole fraction solubility of phenacetin in supercritical carbon dioxide is up to 10^?5. Four density-based semi-empirical models were introduced to correlate the experimental data. Agreement between the model predictions and experimental data is greater with the Adachi-Lu-modified Chrastil model than with the Chrastil model, Méndez-Santiago-Teja model, and the Bartle model and the average absolute relative deviation (AARD) observed is 0.0483. The preparation of fine phenacetin particles by the RESS process under different conditions of extraction temperatures (308.0–328.0 K), extraction pressures (9.0–30.0 MPa), nozzle temperatures (373.0–393.0 K), nozzle diameters (0.1–0.8 mm), and collection distance (20.0–40.0 mm) was investigated. The size and morphology of the resultant particles were analysed by SEM. A remarkable modification in size and morphology can be obtained by condition-optimisation.     

The precipitation of the dispersed phase of liquid medium impurities in a magnetized ferrito-ferromagnetic nozzle

Magnetization curves of ferrito-ferromagnetic filtering nozzles were measured experimentally at various mass ratios between nozzle components. Magnetization curves were approximated. The dependences of residual magnetization on the mass ratio between nozzle components were determined. Magnetic field influence on the precipitation of the dispersed phase of aqueous suspension impurities in ferrito-ferromagnetic nozzles was studied.     

Production of microsized PMMA droplets using electrospraying with various auxiliary fields

To fabricate uniform nano/microsized beads using the electrospraying process, poly(methylmethacrylate) (PMMA) polymer solution is ejected from a reservoir tip to form suspended droplets using the force of a controllable syringe pump. Using a newly designed electrode connected to the nozzle and a field-controllable target electrode, we obtained uniform microsized beads of the solution. Moreover, by using a two-axis x-y stage, we could obtain selective coverage of microsized PMMA droplets on an insulating PET film. To clarify the effect of the applied field conditions, the droplets deposited on a dielectric substrate were characterized under an optical microscope.     

Pumpless dispensing of a droplet by breaking up a liquid bridge formed by electric induction

Dispensing uniform pico‐to‐nanoliter droplets has become one of essential components in various application fields from high‐throughput bio‐analysis to printing. In this study, a new method is suggested and demonstrated for dispensing a droplet on the top plate with an inverted geometry by using electric field. The process of dispensing droplets consists of two stages: (i) formation of liquid bridge by moving up the charged fluid mass using the electrostatic force between the charges on the fluid mass and the induced charges on the substrate and (ii) its break‐up by the motion of the top plate. Different from conventional electrohydrodynamic methods, electric induction enables the droplets to be dispensed on various surfaces including non‐conducting substrate. The use of capillarity with an inverted geometry removes the need of external pumps or elaborates control for constant flow feed. The droplet diameter has been characterized as a function of the nozzle‐to‐plate distance and the plate moving velocity. The robustness of the present method is shown in terms of nozzle length and applied voltage. Finally, its practical applicability is confirmed by rendering a 19 by 24 array of highly uniform droplets with only 1.8% size variation without use of any active feedback control.     

Co-electrospinning of core-shell fibers using a single-nozzle technique

Co-electrospinning is ideally suited for fabricating continuous fibers encasing materials within a polymer sleeve, but requires relatively complex coannular nozzles. A single-nozzle co-electrospinning technique is demonstrated using blends of poly(methyl methacrylate) (PMMA)/polyacrylonitrile (PAN) solutions in dimethylformamide (DMF). The as-spun fibers have outer diameters in the range of 0.5-5 microm and possess a core-shell structure similar to that attained via coannular nozzles. The technique relies on the precipitation of PMMA solution droplets, which become trapped at the base of the Taylor cone issuing the PAN solution jet from its tip. A theoretical analysis shows that the outer shell flow is sufficiently strong to stretch the inner droplet into the Taylor cone, thus forming a core-shell jet. The method seems attractive for technological applications involving macroscopically long and radially inhomogeneous or hollow nano/micro fibers.     

Polymeric nanoparticles from rapid expansion of supercritical fluid solution

In this concept paper we highlight applications of supercritical fluid technology in particle formation and production, especially some recent advances in the rapid expansion of supercritical solutions (RESS) processing technique. We also highlight the simple but significant modification to the traditional RESS by using a liquid solvent or solution at the receiving end of the supercritical solution expansion, or the rapid expansion of a supercritical solution into a liquid solvent (RESOLV), and applications of the technique to the preparation of nanoparticles. In particular, successes and challenges in the use of RESOLV for nanoscale (<100 nm) polymeric particles and the subsequent protection of the suspended nanoparticles from agglomeration are discussed.     

Binary nucleation rates for ethanol/water mixtures in supersonic Laval nozzles

Although the conditions corresponding to the onset of condensation of aqueous-alcohol mixtures have been measured in supersonic nozzles [B. E. Wyslouzil et al., J. Chem. Phys. 113, 7317 (2000)], the true nucleation rates have not. Here, we propose a new analytical method to estimate the temperature, the concentrations of condensable species in both the vapor and the liquid phases, and the amount of the condensate using only the measured static pressure profiles in the nozzle. We applied the method to ethanol/water (CH(3)CH(2)OH/D(2)O or CH(3)CH(2)OD/D(2)O) mixtures and confirmed that the aerosol volume fractions derived from pressure measurements and small angle neutron scattering measurements are in very good agreement when this method is used. Combining the results from the pressure measurements with the number densities of the condensed droplets, measured either by small angle neutron or small angle x-ray scattering, we determined the first quantitative ethanol/water binary nucleation rates in the supersonic nozzle at a temperature of 229±1?K.     

Driving forces of the solute self-organization in an evaporating liquid microdroplet

A method is proposed for preparing solid phases of desired morphologies from microscopic droplets on solid substrates with a GMS 417 Arrayer, which is commonly used for biochip production. The initial droplet of an aqueous solution is about 100 pl (about 100 μm in diameter), and the evaporation time is about 0.5 s. Such small solution volumes are first considered from the viewpoint of the solute self-organization. Aqueous solutions of inorganic molecular and ionic substances, organic dyes, and latex colloid particles in the evaporating droplets are experimentally studied. Various substrates and solute concentrations are used. The morphology of the solid phase formed on the substrate after water evaporation is analyzed with the use of computer simulation of dynamics of the latex particles within the evaporating microdroplet. Elucidating the self-organization mechanisms will facilitate producing of the desired morphology of the solid phase, which can find an application in nanotechnology.