Microstructure of carbonaceous mesophase spherule

Carbonaceous spherules of mesophase were examined by transmission electron microscopy (TEM) and X-ray diffraction to precisely clarify its structure. A series of thin sections were cut from a single spherule with a microtome, and the three-dimensional lamellar structure of the spherule investigated. From 002 dark-field images and selected area electron diffractions (SAD), it was observed that the spherule was of the Brooks-Taylor type, with the lamellae being parallel even at the poles of the spherule. Structural changes within the spherule was studied following carbonization and graphitization. The structure of the resultant coke was essentially that of spherule of mesophase. Size of the lamellae increased as well as. The number of stacking lamellae also increased, but a rapid increase was not seen. The spherules of mesophase show a high degree of homogeneity and an excellent degree of graphitization.     

Sol-gel synthesis, microstructure and adsorption properties of hollow silica spheres

Spherical colloidal particles with a hollow interior and a mesoporous shell are particularly useful for drug delivery and release because such spheres combine the unique properties of hollow interior (for storing the drug) with mesoporous shell (for controlled release). Hollow silica spheres (HSS) with a mesoporous shell were prepared via a sol-gel process in the presence of dual templates polystyrene spheres and cetyltrimethylammonium bromide for creating the hollow core and mesopore shell. The effect of the ratio of silica precursor over polystyrene spheres on particle morphology and pore structure of the HSS was investigated. The adsorption kinetics of methyl blue on the HSS was evaluated and correlated with the mesoporous shell structure.     

Dynamic energy absorption characteristics of hollow microlattice structures

Hollow microlattice structures are promising candidates for advanced energy absorption and their characteristics under dynamic crushing are explored. The energy absorption can be significantly enhanced by inertial stabilization, shock wave effect and strain rate hardening effect. In this paper we combine theoretical analysis and comprehensive finite element method simulation to decouple the three effects, and then obtain a simple model to predict the overall dynamic effects of hollow microlattice structures. Inertial stabilization originates from the suppression of sudden crushing of the microlattice and its contribution scales with the crushing speed, v. Shock wave effect comes from the discontinuity across the plastic shock wave front during dynamic loading and its contribution scales with v². The strain rate effect increases the effective yield strength upon dynamic deformation and increases the energy absorption density. A mechanism map is established that illustrates the dominance of these three dynamic effects at a range of crushing speeds. Compared with quasi-static loading, the energy absorption capacity at dynamic loading of 250 m/s can be enhanced by an order of magnitude. The study may shed useful insight on designing and optimizing the energy absorption performance of hollow microlattice structures under various dynamic loads.     

周期结构空腹梁的动态特性研究

设计了一种内部周期性挖空的梁，它在中高频具有良好的带通和带阻特性，带阻频率范围内的弹性波不能传播。空腹梁由周期单元串联而成，把周期单元分解成薄梁和刚性联接杆等子结构，推导了Timoshenko梁纵向、弯曲振动导纳，给出了刚性联接杆振动导纳，利用传递矩阵法计算得到了周期结构空腹梁的力传递率和带隙位置。数值模拟计算表明，当激励频率在周期结构的阻带之内时，周期结构空腹梁上的位移响应和传递到基础的力响应将大大衰减。     

A蛋白中空纤维膜吸附分离单克隆抗体

首先以人γ－免疫球蛋白为实验物系，对Ａ蛋白中空纤维亲和膜的吸附性能进行了考察，然后应用亲和膜，从小鼠腹水上清液中直接吸附小鼠抗人绒毛膜促性腺激素单克隆抗体，纯化的单克隆抗体经ＳＤＳ－聚丙烯酰胺凝胶电泳检测达到电泳纯。     

U型中空纤维膜水力特性的模型分析

依据水力学原理，建立了竖立式U型中空纤维膜出水量及内压的数学模型，对其结果的理论分析表明：在相同的水头作用下，纤维膜流量随距出水口距离的减小而呈比例增加，但在出水水头较高时，增加的速率要大于出水水头较低时增加的速率；类似地，在纤维内部的不同位置，流量随出水作用水头的增加而增大的速率也是不同的，离纤维出口越近，这种速率的增加就越快，越明显．因此，要想增大出水流量，应尽量提高出水的作用水头，另外还可以在一定范围内增加纤维的长度；纤维内压随距出水口距离的减小而迅速减小，曲线呈类抛物线的形状；离出水口越远，纤维内压随出水水头的增大而增加的速率越大；流量与内压成直线关系，纤维内部距出水口越近，内压随流量增加而增加的梯度越小；由于液体黏度的影响，温度升高，流量增大；但温度越高，流量的增加梯度越小。     

微反应器法纳米颗粒制备技术

微反应器法以其特殊的微反应环境而在纳米颗粒的制备中受到越来越广泛的重视，从微反应器的组成和性质入手，介绍了微反应器内纳米颗粒的形成机理及反应特点，举例说明了该法在纳米颗粒制备中的应用，对该法在纳米颗粒制备中的前景作了展望。     

Agglomerating vibro-fluidization behavior of nano-particles

An experiment study of agglomerating fluidization behavior of three kinds of nano-particles (SiO₂, TiO₂, ZnO) in vibro-fluidized bed (VFB) has been performed. At certain amplitude (3 mm) of vibrations applied, the minimum fluidization velocity decreases, whilst the equilibrium pressure drop increases with increase in the vibration frequency. The minimum fluidization velocity is nearly independent of the vibration amplitude at almost constant frequency of about 40 Hz, whilst the equilibrium pressure increases. Using the linear regression, the Richardson–Zaki exponents of three kinds of nano-particles have been calculated. R–Z analyses indicate that the particulate fluidization degree of cohesive particles can be greatly improved by vibration force.     

中空层状羟基磷灰石微球对溶菌酶的吸附与缓释研究

利用锂钙硼玻璃在磷酸盐溶液中的原位转化反应制备表面多孔且具有中空层状结构的羟基磷灰石(HA)微球,以溶菌酶为蛋白的药物模型,研究了中空层状结构的羟基磷灰石微球对溶菌酶的吸附及缓释特性,结果显示,中空微球对不同浓度的溶菌酶溶液,具有不同的吸附机理,当溶菌酶溶液的浓度低于0.8mg/mL时,溶菌酶的吸附主要发生在微球的外表面,符合Langmuir模型,释放速率较快,48h内基本释放完全;当溶菌酶溶液的浓度高于0.8mg/mL时,溶菌酶扩散进入微球内部及球壁的微孔中,使得吸附量显著增加,满足Henry吸附模型,溶菌酶的释放周期明显增加,可持续释放800h,微球对蛋白具有很好的缓释效果。     

Operating characteristics of the hollow anode glow discharge ion source

In this work, a new shape of a glow discharge ion source with axial extraction has been designed and constructed. High output ion beam current can be extracted axially in a direction normal to the discharge region without using extraction system. Optimization of the distance between the anode and the cathode has been determined using argon gas. It is found that the optimum gap distance between the anode and the cathode is equal to 3.5 mm, where stable discharge current and maximum output ion beam current can be obtained. The discharge characteristics of the ion source at different operating gas pressures have been measured at this optimum distance between the anode and the cathode. A disk of Teflon insulator has been put between the anode and the cathode. This disk was covering the cathode area and reducing the discharge area on the cathode surface for discharge confinement, therefore, a higher output ion beam current could be obtained.     

中空型分子印迹聚合物的制备及其对4-甲基二苯并噻吩的吸附性能研究

以SiO2为载体,4-乙烯基吡啶为功能单体,结合牺牲载体法合成了一种具有特异性识别4-甲基二苯并噻吩的中空型分子印迹聚合物。利用傅立叶变换红外光谱、氮气吸附实验、扫描电镜对形态结构进行了表征。通过在模拟油中的静态吸附试验,对印迹聚合物的吸附性能进行了研究。结果表明,在SiO2表面成功地合成了具有多孔结构的分子印迹层,经过牺牲载体法处理后得到的中空分子印迹聚合物具有更好的表面特性,提高了吸附性能。中空型分子印迹聚合物对4-甲基二苯并噻吩表现出良好的特异性识别性能,吸附动力学满足Langergren准二级动力学方程,等温线符合Freundlich等温线模型,吸附热力学研究表明吸附是自发的吸热过程,在328K下的吸附容量为18.31498mg/g,吸附平衡时间为3h。     

Protein adsorption characteristics of plasma treated polyurethane surfaces

The effect of various plasma surface treatments on the protein adsorption characteristics of two polyurethane elastomers (Acushnet E417-0 [ACx] and Texin 480 AR [TN]) were studied. Both substrates are based upon diphenylmethane 4,4-diisocyanate (MDI) hard segments and polyester soft segments. Adsorption characteristics of the untreated samples were initially established, followed by plasma treated surfaces. Contact angle and 2 h albumin adsorption were determined. (1) Results of this study indicate that the protein adsorption characteristics of crosslinked substrate ACx is more linear than that of non-crosslinked substrate TN. Further, substrate TN adsorbs seven-fold greater protein at a rate four times higher on its surface than ACx.N,N-Ethylene bis (stearamide), a processing aid used in substrate TN, may encourage greater protein adsorption on substrate TN and variation in the soft segment mobility between the substrates also may affect their adsorption characteristics. (2) Plasma treatments using CH₄ and/or C _x F _y chemistries increased the contact angle for both substrates while those with O₂ and O₂/CF₄ decreased the contact angle for the substrates considered. In general, the contact angle of the substrates exhibiting greater protein adsorption was smaller.     

聚砜中空丝支撑膜结构及性能的研究

聚砜为材料，用特制的喷丝头，以干湿法制备了适用于ＰＤＭＳ－ＰＳ复合膜的ＰＳ中空纤维多孔支撑膜，研究了纺丝液配方、温度及纺丝速度、蒸发距离等有关工艺条件对ＰＳ多孔底膜结构的影响，用扫描电子显微镜观察分析其微观结构，对ＰＳ多孔底膜结构与ＰＤＭＳ－ＰＳ复合膜透气性关系进行了初步的讨论。研制的用于空气富氧的直径１００ｍｍ×１０００ｍｍ ＰＤＭＳ－ＰＳ中空纤维复合膜组件的性能参数为：透量１２Ｎｍ＾３／ｈ·０     

羟基磷灰石内连通空心球陶瓷支架的形貌特征及力学性能

利用聚苯乙烯微球模板,采用负压抽滤注浆工艺制备了羟基磷灰石(hydroxylapatite,HA)内连通空心球陶瓷支架,分析了制备工艺对空心球陶瓷的形貌特征和力学性能的影响,并研究了孔隙率与压缩强度的关系.结果表明,空心球陶瓷支架具有连通球形孔及连通球体间隙的独特复合孔结构;当注浆2次,浆料固含量为0.5g/ml时支架的孔壁完整,表面形态有利于骨细胞生长;通过改变工艺参数,得到HA空心球陶瓷的孔隙率为61%～90%,压缩强度为1.1～6.9MPa,孔隙率P与压缩强度σf的关系符合ln(σf)=ln(σf0)-bP方程.     

Surface plasmon resonance imaging measurements of DNA and RNA hybridization adsorption onto DNA microarrays

Surface plasmon resonance (SPR) imaging is a surface-sensitive spectroscopic technique for measuring interactions between unlabeled biological molecules with arrays of surface-bound species. In this paper, SPR imaging is used to quantitatively detect the hybridization adsorption of short (18-base) unlabeled DNA oligonucleotides at low concentration, as well as, for the first time, the hybridization adsorption of unlabeled RNA oligonucleotides and larger 16S ribosomal RNA (rRNA) isolated from the microbe Escherichia coli onto a DNA array. For the hybridization adsorption of both DNA and RNA oligonucleotides, a detection limit of 10 nM is reported; for large (1,500-base) 16S rRNA molecules, concentrations as low as 2 nM are detected. The covalent attachment of thiol-DNA probes to the gold surface leads to high surface probe density (10(12) molecules/cm2) and excellent probe stability that enables more than 25 cycles of hybridization and denaturing without loss in signal or specificity. Fresnel calculations are used to show that changes in percent reflectivity as measured by SPR imaging are linear with respect to surface coverage of adsorbed DNA oligonucleotides. Data from SPR imaging is used to construct a quantitative adsorption isotherm of the hybridization adsorption on a surface. DNA and RNA 18-mer oligonucleotide hybridization adsorption is found to follow a Langmuir isotherm with an adsorption coefficient of 1.8 x 10(7) M(-1).     

Correlation between structure and adsorption characteristics of oriented polymers

In a more or less swollen state the methods by which the fiber structure is determined provide more realistic information about their properties and structure in wet conditions, because of the swelling and alteration of fiber structure. These results, however, of sorption analyses are very rarely in accordance with those obtained from structural analyses. One such ”wet” method is the iodine sorption test. The iodine sorption test was originally proposed by Schwertassek [1] and since then has been constantly modified by other researchers [2–7]. In this presented work the correlation between different structural parameters, iodine sorption (ISV) and conventional sorption analyses (water vapor sorption and water retention power) of polyamide 6 (PA 6) and cellulose fibers was studied. The results demonstrate that the iodine sorption value best correlates with the degree of crystallinity and the perfection of the crystalline phase of both polyamide and cellulose fibers. The correlation is linear. Received: 25 August 2000 / Reviewed and accepted: 28 August 2000     

表面活性剂在纳米粉体制备中的应用

本文论述了表面活性剂在Al2O3纳米粉体制备、改性等方面的应用,并简要介绍表面活性剂在纳米粉体修饰中的作用。