Effect of lyophilization process on the physical properties and stability of tanshinone IIA microemulsions

Tanshinone IIA microemulsions were successfully prepared by freeze-drying method. Annealing was involved in the freeze-drying process, and the effects of lyophilization process on the physical properties including particle size, surface tension, glass transition temperature, and X-ray diffraction pattern were studied. The lyophilized samples were slightly superior to those untreated with lyophilization in terms of surface properties. Moreover, the physical stabilities of tanshinone IIA microemulsions related to insoluble particles and cloud point thermodynamic were also investigated. The lyophilized samples with annealing showed better physical stabilities than those not lyophilized or lyophilized without annealing.     

Optimization of the freeze-drying process for microemulsion systems

Abstract

The aim of this work was to develop a freeze-dried microemulsion using Design of Experiment and loaded with Amphotericin B, which is quite unstable in aqueous media, as a drug model. Different types of cryoprotectants were studied. The microemulsion containing maltose at 5% (w/w), frozen at a temperature of –80?°C and performed with a 24?h of freeze-drying time, yielded the best results. The freeze-drying process reduced the microemulsion droplet size and does not change the AmB content. Therefore, microemulsions containing maltose are suitable for drug incorporation, and the freeze-drying was able to enhance the drug stability in the system.     

Effect of annealing process on IR transmission and mechanical properties of spark plasma sintered Yttria

In this study, fully dense Yttria ceramics were successfully fabricated by spark plasma sintering (SPS) at temperatures of 1300 and 1350 $℃$. The effects of post-annealing on IR transmission were investigated by Fourier transform infrared spectroscopy (FTIR) at various temperatures ranging from 1050 to 1250 $℃$. It was found that the optimum annealing temperature depends strongly on the sintering temperature. Annealed samples showed white opaqueness mainly due to the increase and coalescence of pores after annealing and showed an absorption band around 6.6 $\mu m$ which limits usage of yttria in IR applications. Sintering at 1350 $℃$ and annealing at 1250 $℃$ led to the maximum IR transmittance above 80% at wavelength of 5 $\mu m$ for a 3.5-mm-thick sample. The hardness and the fracture toughness of the samples were analyzed in detail and hardness of 9.2 GPa and fracture toughness of 1.65 MPa m^1/2 were obtained for the above sample.     

Effect of relative humidity on the oxidative and physical stability of encapsulated milk fat

Milk fat was used in this work as a model to study the effects of humidity and physical properties on lipid oxidation. Although milk fat is considered a relatively stable fat because of its low content of unsaturated FA, it can oxidize significantly under certain conditions, as observed, for example, in the case, of dairy-based powders. Humidity and physical properties have a profound influence on the oxidative stability of powders, containing fat, and these factors affect the surface and encapsulated fractions of the fat differently. To examine these effects, encapsulated milk fat powders were stored under conditions of controlled relative humidity. Oxidation of the encapsulated fat as assessed by measurements of PV, losses of FA, and hexanal production increased, with increasing relative humidity (RH). At higher RH, moisture penetrates into the hydrophilic wall, interacting with and plasticizing the components, thereby making them less effective as moisture and oxygen barriers. Total oxidation of the powders was strongly influenced by the extent of oxidation in the encapsulated fraction (>98% of total lipids) although the surface fat fraction was oxidized more rapidly. Better protection against oxidation was obtained when fats were encapsulated and stored at 14 and 44% RH than at 52% RH.     

Electrical and chemical stability engineering of solution-processed indium zinc oxide thin film transistors via a synergistic approach of annealing duration and self-combustion process

The electrical and chemical stability of solution-processed indium zinc oxide (IZO) channel thin-film transistors (TFTs) were engineered via a synergistic approach of annealing duration and self-combustion process. In particular, the amorphous IZO TFTs that were thermally treated at 400 °C for 3 h using the specific precursor combination to generate internal self-combustion energy showed the best electrical performance [high saturation mobility (μ_SAT)=2.7 cm²/V s] and stability [low threshold voltage shift (ΔV_TH) under positive bias stress of 10.5 V] owing to the formation of oxide films with excellent metal–oxide–metal (M–O–M) bonds, fewer impurities, and an amorphous phase compared to IZO TFTs using other precursor formulas and annealing times. Longer annealing times led to a saturated M–O bond ratio and crystallization via extreme thermal annealing, which induced electrical degradation (low μ_SAT and high ΔV_TH) of IZO TFTs. In the wet chemical patterning of electrodes, conventional acidic and basic wet etchants cause severe damage to the surfaces of the IZO channels; thus, insufficiently annealed IZO TFTs exhibited considerable degradation in terms of their on-current level and mobility. Alternatively, the TFTs subjected to an excessively long-term thermal annealing showed only a moderate decrease in mobility with the formation of small nanocrystals.     

Effect of functional monomer on the stability and film properties of thermosetting core-shell latexes

Functionalized core-shell latexes were prepared by copolymerization of butyl acrylate and methyl methacrylate with 2-hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA), which were added during the first or second stages of polymerization, respectively. The HEMA and MAA concentrations were increased while the equivalent ratio of functional groups remained constant. Colloidal stability, particle size, particle size distribution, film properties and morphology were studied as functions of functional monomer content. The upper limit functionality content was limited by the stability of the system during synthesis. A bimodal particle size distribution was observed for high concentrations of functional monomers. Increase in carboxyl and hydroxyl functionalities improved tensile strength and modulus for un-crosslinked films, and generally higher tensile strength, tensile modulus and storage modulus at high temperature were obtained after the functional latexes were crosslinked with a cycloaliphatic diepoxide.     

Effect of freeze-drying treatment on the optical properties of SPS-sintered alumina

This study looks at the influence of alumina powder processing on the preparation of transparent alumina by Spark Plasma Sintering (SPS). Zeta potential measurements were carried out on alumina suspensions in order to determine the best dispersion conditions. Stable slurries were submitted to a spray freeze drying process and their sintering behavior was compared with the corresponding non spray freeze dried powders. Transparent alumina samples were successfully prepared from alumina powders by Spark Plasma Sintering. An optical model considering pore and grain size distributions has been developed to obtain information about porosity in dense materials. It was found that the final density and, accordingly, the optical properties were improved when spray freeze dried starting powder was used.     

二溴邻硝基偶氮胂的纯化,性质及其钍络合物的稳定常数

研究了钍的新试剂二溴邻硝基偶氮砷（ＤＢＯＮＡ）的纯化方法和性质。测定的其离解常数（ｐＫａ）、质子化常数（ｌｏｇＫｐ）分别为１０．１７和－４．７５。求得钍络合物的组成为１：２，其积累稳定常数为２７．９８。     

Effect of organoclay on the morphology, phase stability and mechanical properties of polypropylene/polystyrene blends

The effect of organically modified clay on the morphology, phase stability and mechanical properties of polypropylene (PP) and polystyrene (PS) blends was studied using three molecular weight grades of PP. Maleated polypropylene was used, at a PP-g-MA/organoclay ratio of 1, to preferentially promote dispersion of the organoclay in the PP matrix. The MMT content was fixed at 3 wt% based on the PP/PP-g-MA/MMT phase and the PS content was varied from 0-100 wt% in the blend. All blends were processed using a twin screw extruder. The organoclay resides in the PP phase and at the PP/PS interface. The dispersed PS particle size is significantly reduced by the presence of MMT, with maximum decrease observed for the low viscosity PP compared to its blend without MMT. The blends with MMT did not show any change in onset of co-continuity, though MMT shifts the phase inversion composition toward lower PS contents. The phase stability of the blend was significantly improved by the presence of MMT; for blends annealed at 210 °C for 2 h the dispersed phase particle size increased by as much as 10x without MMT with little change was noted with MMT present in the blend. The tensile modulus of blends improved with the addition of MMT at low PS contents. Blends based on the highest molecular weight grade PP showed increase in the tensile yield stress up to 40 wt% PS in the absence of MMT. The tensile strength at break for blend increased slightly with MMT while elongation at break and impact strength decreased in the presence of MMT. Surface energy analysis model was used to predict the orientation and equilibrium position of the clay platelet at the interface based on the surface energies.     

Effect of the full refining process on rice bran oil composition and its heat stability

The effects of the chemical refining process on the minor compounds of rice bran oil and its heat stability were investigated. After 8 h of heating, about 50% and 30% of total tocopherols remained in crude and refined rice bran oil, respectively. The individual tocopherols were differently affected by the refining process. The order of heat stability of tocopherols and tocotrienols in crude oil was found to be different from that in fully refined oil. A similar tendency was observed for sterols. After 8 h of heating, 65% and 72% of total sterols, and 14% and 46% of sterol esters, of crude or fully refined rice bran oil, respectively, disappeared. The heating process led to a 4% and 10.3% increase in polymer contents in crude and refined rice bran oil, respectively. Although refined rice bran oil showed good heat stability, when compared to crude oil its heat stability was decreased to some extent.     

Effect of nickel incorporation on the acidity and stability of HZSM-5 zeolite in the MTO process

A study has been carried on the effect of Ni incorporation on the acidity (acid strength distribution and total acidity), on the hydrothermal stability of a HZSM-5 zeolite and on the kinetic performance of this catalyst in the MTO process at high temperature (up to 500 °C, in order to increase selectivity to olefins) and when there is a high water content in the feed (in order to minimise deactivation by coke). The incorporation of Ni in the HZSM-5 zeolite implies a decrease in the total acidity and in the acid strength of the zeolite and, consequently, the activity of the catalyst decreases. Nevertheless, the catalysts with Ni are hydrothermally more stable than the parent zeolite catalyst. A Ni content around 1 wt% is the optimum, as it allows for uninterrupted operation in reaction–regeneration cycles, with water contents higher than 50 wt% in the medium, without irreversible deactivation, whereas a higher Ni content produces an unnecessary loss of initial activity.     

Effects of annealing on wettability and physical properties of SnO thin films deposited at low RF power densities

The SnO thin films were deposited at low RF power densities by RF magnetron sputtering. According to XRD and XPS analyses, the SnO thin film comprised nanocrystalline orthorhombic SnO with a (110) orientation. Reducing RF power density resulted in better nanocrystallinity, changing hydrophobicity to hydrophilicity, and increasing the optical transmission in the UV–vis–NIR region. After annealing, the SnO thin film favored p-type conductivity and hydrophilicity. As the annealing temperature increased, the coexistence of nanocrystalline orthorhombic SnO and tetragonal SnO₂ in the film clearly increased the optical transmission in the ultraviolet region. The SnO thin films after annealing at 500 ℃ in vacuum and N₂ (200 sccm) exhibited a higher hole mobility and a better optical selection in the ultraviolet region, respectively.     

伏立康唑PLGA纳米微粒的制备及其形态和释放特点分析

目的制备伏立康唑PLGA纳米微粒,并分析其形态及释放特点。方法采用乳化-溶剂挥发法制备伏立康唑PLGA纳米微粒,用激光粒径分析仪及扫描电镜分别进行分散性和形态学分析,经HPLC分析其载药量及释放特点。结果经激光粒径分析,样品粒径峰值为(126±20)nm,分布指数为1.5。电镜观察颗粒分布均匀,表面光滑。HPLC分析载药量为(1.9±0.6)%,包封率约为12%,24h内存在突释,第2天到第8天缓慢释放。结论已成功制备了伏立康唑PLGA纳米微粒,能实现缓慢释放,减少给药次数的目的。     

Effect of internal stresses on the structure and physical and mechanical properties of a complex glass fibre

The correlations of internal stresses arising in a complex glass fibre during with the shape of the fibre as a function of the surface properties of the lubricant and the tension of the fibre in the pack layers were obtained in differential and integral form. The results of the studies confirm the validity of the proposed analytical model of formation of internal stresses in a complex fibre during its drying. The conclusion that the different lengths of the monofilaments in the complex fibre is the basic cause of formation of the twisted structure of the complex fibre was experimentally confirmed.Fiberglass Plastics—Certificate AF, Moscow. Translated from Khimicheskie Volokna, No. 1, pp. 46–48, January–February, 1994.     

提高热媒系统稳定性

介绍了热媒系统运行的现状,分析了导致热媒膨胀槽导热油温度高的原因。包括:导热油劣化、员工技能水平低、1套热媒系统2个膨胀槽、一、二车间热媒膨胀槽高度不一。针对上述原因,制定了相应对策,提高了热媒系统的稳定性,降低了运行的经济成本。     

Effect of polymer additives and process temperature on the physical properties of bitumen‐based composites

Polymer modified bitumen (PMB) is a binder obtained by the incorporation of polymer into the bitumen by mechanical mixing or chemical reaction. This study deals with the modification of bitumen with three types of polymers (LDPE, EVA, and SBS) in the presence of filler (CaCO₃). The morphological, mechanical, rheological properties, and thermal conductivity of the PMBs have been analyzed by scanning electron microscopy, tensile testing, melt flow index (MFI) measurements and hot wire method, respectively. The results indicate that the above‐mentioned properties of PMBs are influenced by polymer and bitumen nature and its composition. The mechanical properties of composites prepared at different temperatures exhibit small differences. In general, the inclusion of polymer increases tensile strength and Young's modulus and reduces percentage strain and MFI values, also, polymer inclusion reduces the thermal conductivity values of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of annealing on the properties of waterborne polyurethane adhesive containing urethane-based thickener

Different amounts of hydrophobically modified ethoxylated urethane-based thickener (HEUR) were added to improve the rheology of waterborne polyurethane adhesives. The thickened solid adhesive films were thermally annealed and characterised by IR spectroscopy, plate–plate rheology, dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Hydrogen bonds played a key role in the thickening mechanism of polyurethane dispersions containing urethane-based thickener, along with ionic adsorption and micelles formation between hydrophobic groups. The adhesion properties were measured from T-peel test of leather/polyurethane adhesive/vulcanised styrene-butadiene rubber joints. Optimal results were obtained when water in the waterborne polyurethane adhesive (just before joint formation) was removed under open air, while forced air drying impeded the complete removal of water. On the other hand, the thermal annealing did not greatly affect the rheological and thermal properties of the thickened polyurethanes.     

Effect of annealing on the structure and magnetic properties of CoFe2O4:SiO2 nanocomposites

The decomposition of succinate type precursors obtained by a modified sol-gel method using cobalt and iron nitrates, 1,4-butanediol and tetraethylorthosilicate, followed by the formation of single phase cobalt ferrite embedded in the silica matrix by annealing at 400–1100 °C was studied. The thermal analysis indicated the formation temperature of succinate type precursors, while the Fourier transform infrared spectroscopy (FT-IR) data confirmed the formation of the precursors in the pores of silica matrix. The formation of CoFe₂O₄ was investigated by X-ray diffraction and FT-IR, the size and shape of the nanoparticles by transmission electron microscopy, while the resulted microstructures by scanning electron microscopy. The crystallinity and crystallites size increased with the annealing temperature. The hysteresis loops revealed a direct relationship between annealing temperature and saturation magnetization in constant coercive field. The particle size of ferrite powders is critically dependent on the annealing temperature.     

Effect of aluminum annealing on the galvanoluminescence properties of anodic oxide films formed in organic electrolytes

The galvanoluminescence (GL) properties of anodic oxide films formed in organic electrolytes were investigated at different aluminum annealing temperatures. The results of the spectral measurements showed two different types of GL sources: carboxylate ions incorporated in oxide films during the anodization and the molecules AlH, AlO, Al₂, AlH₂, also formed during anodization process and already recognized in the case of inorganic electrolytes. The latter was related to gamma alumina crystalline regions formed by annealing of the aluminum samples at temperatures above 500 °C.