Diffraction-like effects in a highly concentrated W/O emulsion: a PFG NMR study

Diffraction-like effects have been observed by applying pulsed field gradient (PFG) nuclear magnetic resonance (NMR) to a highly concentrated water-in-oil (W/O) emulsion, made up of the nonionic surfactant C12E4 [CH3(CH2)11(OCH2CH2)4OH], n-decane, and brine [1 wt% NaCl(aq) solution]. The pulsed field gradient NMR data show one pronounced maximum and the shoulder of a second maximum in the attenuation curve of the NMR signal from water, the so-called Bragg interference peaks. From the diffraction-like peaks, the average distance (center to center) between the emulsion droplets can be obtained, in this case related to the average size of an emulsion droplet. Furthermore, we note that the long-term stability of the emulsion can be followed by pulsed field gradient NMR.     

W/O微乳液对强碱体系中钒的萃取

实验制备了水/N263/异戊醇/煤油组成的反相胶束和W/O微乳液。通过该微乳液对低浓度钒酸钠水溶液进行萃取,研究了碱浓度对钒萃取的影响。同时研究了在pH=13的强碱条件下,内水相组分、N263浓度、异戊醇浓度、温度、水乳比及萃取时间对钒萃取率的影响。研究表明,随着料液碱浓度的增高,微乳液对钒的萃取率逐步降低;当料液pH=13,内水相为0.6 mol/L NaOH+0.6 mol/L NaCl、N263浓度6%、异戊醇浓度12%、温度35℃、水乳比=3、搅拌时间3 min时,浓度为1 g/L的钒的料液经微乳液一级萃取后,可降至100 mg/L,萃取率达到90%。     

乳状液膜法分离铜工艺中的溶胀问题

研究了表面活性剂、载体对分离提铜时乳状液膜溶胀率的影响,结果表明,以表面活性剂LMS-2为乳化剂,Acorga M5640为载体的乳状液膜体系,分离提铜15min后,铜的迁移率达到94.6％,显示出良好的工业应用前景。     

正相微乳液法制备负载染料的二氧化硅荧光纳米粒子

采用正相微乳液法制备了负载油溶性染料2,5-二[4-(2-N,N-二苯胺苯乙烯基)苯基]-1,3,4-噁二唑(PASPO)的二氧化硅荧光纳米粒子.透射电子显微镜和红外光谱表征结果显示,荧光纳米粒子呈单分散球形,平均粒径约为30 nm.利用紫外光谱和荧光光谱对染料PASPO和荧光纳米粒子的光学性能进行表征,发现其光谱基本一致,从氯仿到N,N-二甲基甲酰胺(DMF),随着溶剂极性的增大,两者的紫外光谱分别蓝移了3和5 nm,荧光光谱分别红移了54和50 nm,表明染料PASPO负载于荧光纳米粒子之后光学性能并没有受到显著的影响.荧光纳米粒子在水中分散后仍然具有较强的荧光,因而可以直接用于含水生物样品的检测,对于发展用于生物标记和生物检测的高灵敏度荧光纳米探针有着重要的意义.     

Preparation, characterization, and in vitro release of ibuprofen from AI2O3/PLA/PMMA composites

PURPOSE: To investigate in vitro the mechanisms involved in the gastro-intestinal absorption of the HIV protease inhibitor, saquinavir mesylate (Invirase), whose oral bioavailability is low, variable, and significantly increased by co-administration with ritonavir, also an HIV protease inhibitor but with higher oral bioavailability. METHODS: Confluent epithelial layers of human Caco-2 cells mimicking the intestinal barrier. RESULTS: Both saquinavir and ritonavir showed polarized transport through Caco-2 cell monolayers in the basolateral to apical direction (secretory pathway), exceeding apical to basolateral transport (absorptive pathway) by factors of 50-70 and 15-25, respectively. Active efflux was temperature dependent, saturable and inhibited by verapamil and cyclosporin A. Saquinavir and ritonavir decreased each other's secretory permeability and hence elevated their net transport by the absorptive pathway. CONCLUSIONS: Saquinavir and ritonavir are both substrates for an efflux mechanism in the gut, most likely P-glycoprotein, which acts as a counter-transporter for both drugs. Together with sensitivity to gutwall metabolism by cytochrome P-450 3A, this may partially account for the low and variable oral bioavailability of saquinavir in clinical studies and for its increased bioavailability after co-administration with ritonavir.     

Evaluation of process parameters involved in chitosan microsphere preparation by the o/w/o multiple emulsion method

Chitosans are interesting biopolymers largely studied for applications in the medical and pharmaceutical fields. In this work, an o/w/o multiple emulsion technique was used for the preparation of hydrophobic drug loaded microspheres. Moreover, the influence of critical variables (concentration of acetic acid in the polymer solution and drug-polymer ratio) on microsphere morphology and drug content was evaluated. Two chitosans of different molecular weights and deacetylation degree were employed; ketoprofen, a non-steroidal anti- inflammatory drug, was chosen as the hydrophobic model drug. The multiple emulsion method produced well-formed microspheres with good yields. Acetic acid concentration in the polymeric solutions influenced particle size and drug content of the microspheres. The highest drug encapsulation efficiencies were obtained for the lowest theoretical drug/chitosan ratio.     

Production of corrosion-resistant S420K2W and S460K2W structural steel

The alloying of steel resistant to atmospheric corrosion is discussed. The differences and similarities of the Russian GOST, European EN, and United States ASTM standards regarding the chemical composition of such steel are analyzed. The prospects for the production of corrosion-resistant high-strength steel sheet exceeding the requirements in the EN 10025-5 standard are considered. In trials, the possibility of producing steel sheet with elevated low-temperature impact strength is demonstrated. Production technology for high-strength steel resistant to atmospheric corrosion is developed.     

Dislocations in continuous filament reinforced W/NiAl and Al2O3/NiAl composites

Continuous filament reinforced W/NiAl and Al₂O₃/NiAl composites (as-processed, annealed, and thermally cycled) have much higher dislocation densities than that of monolithic NiAl. These higher dislocation densities resulted from the relaxation of thermal residual stress, which developed during the cooling of the sample from elevated temperatures and was caused by the difference in the coefficients of thermal expansion between the matrix and the reinforcement. The dislocation density in the region adjacent to the matrix-filament interface was high and decreased only slightly with distance from the interface in the 30 vol pct composites. The as-processed and annealed composites exhibited a rather homogeneous dislocation density in the matrix. After thermal cycling, these composites showed no large difference in the dislocation density and morphology. However, there were local regions of lower dislocation densities. This difference was examined in relationship to filament fracture, surface matrix cracking, and degree of bonding.     

A/A/O/O工艺在包钢焦化废水处理中的应用

焦化废水处理是焦化厂环境污染治理工作中的一个难题.包钢焦化厂在酚氰废水处理站改扩建工程中采用了国内先进的A/A/O/O工艺.该工艺不但能很好地去除废水中的酚、氰、CODcr等污染物,还能有效降解氨氮浓度,使之达到国家二级排放标准.     

钨铜功能梯度材料中掺杂TiC和La2O3性能比较研究

采用超高压力通电烧结工艺制备了添加1%TiC和1%La2O3的W/Cu 功能梯度材料(FGMs),分析研究了其烧结性能、层间剪切强度及抗热冲击性能.此功能梯度材料孔隙度在6%左右;梯度层间剪切强度从富W侧向富Cu侧逐步增高;在激光功率密度200MW/m2下,对此材料进行激光热冲击试验,冲击1 000次,含1%La2O3钨-铜梯度材料表面没有损坏,而含1%TiC钨-铜梯度材料表面出现裂纹.     

W,N共掺杂TiO_2/SiO_2/Fe_3O_4磁性光催化剂研究

以Fe3O4纳米颗粒为内核,SiO2惰性层为隔离层和钛酸四正丁酯为前驱体,钨酸铵、硝酸铵为掺杂源,采用低温溶胶法制备磁负载型的钨、氮共掺杂二氧化钛磁性光催化剂;通过XRD、SEM、DRS和IR等表征手段,对低温溶胶制备磁负载型的钨、氮共掺杂的二氧化钛磁性光催化剂的性质进行研究。结果表明:催化剂为锐钛矿晶型,球形纳米颗粒,禁带宽度降低了0.66eV。以氙灯模拟太阳光降解甲基橙,光照1h,催化剂降解率均达到90%以上。     

添加1%TiC和1%La2O3钨/铜FGM的性能研究

通过超高压力通电烧结制备了添加1%TiC和1%La2O3的W/Cu FGM,研究了其烧结、层间剪切强度及抗热冲击性能;此功能梯度材料气孔率在11%左右;在激光功率密度200 mW·m-2下,对此材料进行激光热冲击试验,冲击1000次,含1%La2O3钨-铜梯度材料表面没有损坏,而含1%TiC钨-铜梯度材料表面出现裂纹.并对此材料抗热冲击现象进行了简要分析.     

Y_2W_3O_(12)和Yb_2W_3O_(12)的制备及其负热膨胀性能

利用液相沉淀法制备了Y2W3O12和Yb2W3O12粉体。经室温XRD测定,Y2W3O12(空间群为Pnca)和Yb2W3O12(空间群为Pbcn)皆为单一的正交相。在50-800℃温度区间对两种粉体进行高温XRD测试,并利用软件TOPAS3.0对其在不同温度下的XRD图谱进行精修,发现Y2W3O12和Yb2W3O12都具有较大的负热膨胀特性,经计算两者的线热膨胀系数(αl)平均值分别为-6.38×10-6℃-1和-4.18×10-6℃-1。与高温固相反应法相比,液相沉淀法大大缩短了粉体的合成周期,降低了合成温度。     

Effect of formation of surface complex between hydroxypropylcellulose and sodium dodecylsulfate on dispersion/flocculation of O/W-type emulsion of soybean oil

An O/W-type emulsion of soybean oil (theta v = 0.05) was prepared in the presence of various concentrations of hydroxypropylcellulose (HPC) and sodium dodecylsulfate (SDS). The mean diameter (d) of secondary particles of the oil droplets decreased with concentrations of SDS and HPC after attaining a maximum at [SDS] = 5 mmol/dm3 and [HPC] = 10(-3) g/dl, while the relative viscosity (eta rel) of the emulsion increased with an SDS concentration after attaining a minimum around 5 mmol/dl3 when the HPC concentration was kept constant. These facts were explained in terms of the formulation of a surface complex by hydrophobic interaction between SDS and HPC adsorbed on the surface of the droplets. When the concentration of SDS is low, it bridges between the HPC segments intra- and intermolecularly on and between the particles, resulting in shrinking of the HPC surface layers as well as in bridging among the particles. Therefore, the total volume of the secondary particles effective on eta rel decreases while the d-value increases with the SDS concentration. When the concentration becomes high, binding ratio of SDS to HPC also increases and the segments are repulsive each other owing to the negative charges given by the bound SDS. As a result, the adsorption layer swells and the secondary particles are redispersed. This fact causes an increase in eta rel and a decrease in d-value with a concentration of added SDS.     

S100beta induces neuronal cell death through nitric oxide release from astrocytes

The glial-derived neurotrophic protein S100beta has been implicated in the development and maintenance of the nervous system. S100beta has also been postulated to play a role in mechanisms of neuropathology because of its specific localization and selective overexpression in Alzheimer's disease. However, the exact relationship between S100beta overexpression and neurodegeneration is unclear. Recent data have demonstrated that treatment of cultured rat astrocytes with high concentrations of S100beta results in a potent activation of inducible nitric oxide synthase (iNOS) and a subsequent generation of nitric oxide (NO), which can lead to astrocytic cell death. To investigate whether S100beta-induced NO release from astroctyes might influence neurons, we studied S100beta effects on neuroblastoma B104 cells or primary hippocampal neurons co-cultured with astrocytes. We found that S100beta treatment of astrocyte-neuron co-cultures resulted in neuronal cell death by both necrosis and apoptosis. Neuronal cell death induced by S100beta required the presence of astrocytes and depended on activation of iNOS. Cell death correlated with the levels of NO and was blocked by a specific NOS inhibitor. Our data support the idea that overexpression of S100beta may be an exacerbating factor in the neurodegeneration of Alzheimer's disease.     

偏重亚硫酸钠—空气法处理氰化尾渣

采用偏重亚硫酸钠—空气法处理氰化尾渣进行脱氰的研究,考察Na2S2O5浓度、Cu2+浓度、空气速率、初始pH和反应时间对脱氰效果的影响。结果表明,在Na2S2O5浓度0.2g/L、Cu2+浓度80mg/L、空气鼓入速率250mL/min、初始pH≈10的条件下反应2h,氰化尾渣矿浆中全氰浓度从91.5mg/L降到0.2mg/L左右,可以满足GB8978-1996污水综合排放标准。     

Diffusional reactions during processing of TIMETAL 21S/Al2O3 composites

The stability of an Al₂O₃ reinforcement in TIMETAL 21S has been investigated by annealing diffusion couples and consolidated fiber composites at 1100 °C, 900 °C, and 750 °C. Diffusion couple studies indicate that γ-TiAl, α ₂-Ti₃Al, and α-Ti(Al,O) phases can form upon annealing above the β transus of TIMETAL 21S, but γ-TiAl, α ₂-Ti₃Al, and a ternary T phase form during annealing below the β transus. The phases developed during diffusional interaction define a diffusion path between TIMETAL 21S and Al₂O₃. A coating of Nb, Mo, or Ta between TIMETAL 21S and Al₂O₃ acts as a diffusion barrier, but the coatings can diffuse into TIMETAL 21S at high temperature. In agreement with a kinetics analysis, a 2-μm-thick interface coating of Nb, Mo, or Ta in the TIMETAL 21S/Al₂O₃ composite can prevent the reaction during processing (2 hours at 850 °C or 900 °C) with no detectable diffusion into the matrix. If there are imperfections such as pinholes or cracks present in the diffusion barrier, the reaction quickly starts at the interface and does not remain confined at the imperfection; rather, it progresses along the interface. The mechanism for progressive development of interface reaction at a discontinuity in the diffusion barrier has been proposed. The analysis of the diffusional interface reactions in this work has identified some of the governing design concepts for development of robust high-temperature titanium-based composites.     

Equilibria in the systems C−O−S and C−O−S−H as related to sulfur recovery from sulfur dioxide

Equilibrium phase diagrams for the titled systems, showing gas composition as a function of temperature for the carbon and sulfur-saturation surfaces, were calculated from thermochemical data on the numerous gas species present. The recent experimental work of Drowart,et al ¹. was used to obtain consistent thermodynamic behavior for the seven vapor polymers of sulfur (S _n ,n=2 to 8). For the system C?O?S?H, only the pseudo-ternary at the constant atom ratio H/C=4.0 is presented. An iterative procedure, adapted for the digital computer, was used to solve the complex equilibria involved. The influence of the equilibrium chemistry on the design of processes to reduce SO₂ with C, CO, and CH₄ is discussed. In all cases, production of sulfur vapor reaches a sharp maximum at the gas composition having the atom ratio (H+C)/O =(1+X)/(2+X/2), whereX is the atom ratio H/C in the reducing agent. Reducing agents with lower values ofX yield better sulfur recovery because of the smaller residual amount of H₂S and SO₂ in the reacted gas.