马拉硫磷微胶囊剂的气相释放行为的研究

本文详细叙述了农药微胶囊剂活性组分气相瞬时释放速率的测定装置和测定方法,并采用所述方法测定以天然高分子材料海藻胶——明胶为囊膜的马拉硫磷微胶囊剂的气相释放行为和壁膜渗透率的研究结果.     

Hydrogen evolution characteristics of Ni–Mn microencapsulated MlNi3.03Si0.85Co0.60Mn0.31Al0.08 alloys in 6 M KOH

Nickel–manganese alloys were coated from sulphate baths by electrodeposition with ‘Packed Bed’ technique on the surface of proprietary lanthanum rich non-stoichiometric MlNi_3.03Si_0.85Co_0.60Mn_0.31Al_0.08 (Ml = lanthanum rich misch metal) hydrogen storage alloy particles. The structure and nature of the microencapsulated alloys were characterized using X-ray diffraction (XRD) and electron paramagnetic resonance (EPR). The hydrogen evolution reaction (HER) was investigated in 6 M KOH at 30 °C by galvnostatic cathodic polarisation technique. The effects of Ni/Mn ratio in the bath and deposition current density were studied. Among the investigated depositions, Ni₁₅₀Mn₁₀₀ (30) and Ni₁₅₀Mn₁₀ (60) (concentration of Ni and Mn salts in electrodeposition bath given in grams per liter; electrodeposition current density (CD) given within brackets in milliamphere per square centimeter) coated samples exhibited the highest activity towards the HER. It can be concluded that disordered paramagnetic coatings with Ni concentrations above 80 at.% exhibit higher catalytic activity towards HER. The Tafel mechanism is the easiest pathway for HER on most of the studied coatings. However, some of the Ni-rich coatings prefer the Volmer–Tafel path and one sample [Ni₁₅₀Mn₁₅₀ (80)] prefers the Heyrovsky–Volmer path.     

乳液微封装技术制备聚苯乙烯空心微球

介绍了乳液微封装技术制备不同直径空心聚苯乙烯微球的工艺技术,着重研究了表面活性剂、电解质、水溶性聚合物对多重乳液的稳定性、微球的直径以及微球表面光洁度的影响。在选定的实验参数下,制备得到直径150～3000μm,壁厚0.8～15μm,表面粗糙度Ra约为4nm,微球同心度≥95%的空心聚苯乙烯微球。     

Synthesis and characterization of β-cyclodextrin inclusion complexes of thymol and thyme oil for antimicrobial delivery applications

Microencapsulation with β-cyclodextrin (β-CD) as a delivery platform offers a promising application for natural antimicrobial delivery for food safety. Hence, this study aimed to characterize inclusion complexes of thymol and thyme essential oil with β-CD and their resulting antimicrobial activities. Inclusion complexes were prepared by kneading (KN) and freeze-drying (FD) methods. The entrapment efficiencies ranged from 71 to 83 g/100 g with higher (P < 0.05) values for thymol and FD particles. All particles showed irregular shapes and sharp edges with significant differences in size distribution and strong tendency to agglomerate. FD produced higher (P < 0.05) particle sizes than KN method. Differential Scanning Calorimetry (DSC) analysis confirmed inclusion complexes formation between β-CD and both compounds. Phase solubility tests indicated B_S-type complexes formation between thymol and β-CD. All compounds effectively inhibited bacterial growth within the concentration range tested. Free thyme oil showed higher (P < 0.05) antimicrobial activity than thymol, and FD β-CD inclusion complexes were able to inhibit Escherichia coli K12 at lower (P < 0.05) active compound concentrations than corresponding free oils. Antimicrobial activities of β-CD inclusion complexes against total viable counts in pork meat system throughout storage were observed. The FD method showed to be the best encapsulation method with enhanced antimicrobial activity for both compounds.     

二氢杨梅素微胶囊化壁材的优化研究

本文研究了喷雾干燥制备二氢杨梅素微胶囊的壁材组成优化,选用阿拉伯胶和麦芽糊精作为二氢杨梅素微胶囊的壁材,结果表明,当微胶囊壁材组成为:二氢杨梅素与壁材的比例为15:85(m/m),阿拉伯胶与麦芽糊精的比例为70:30(m/m),乳化剂添加量为0.5 %(v/m)时,该壁材具有较好的性能.     

Liposomal microencapsulation using the conventional methods and novel supercritical fluid processes

BackgroundLiposomes are spherical phospholipid vesicles with the capability of versatile microencapsulation of hydrophilic and lipophilic compounds. Organic solvent residue has always been a concern in conventional methods of liposome generation.Scope and approachDense gas techniques using supercritical carbon dioxide as the phospholipid-dissolving agent can provide a green solution for reduction or avoidance of organic solvent use.Key findings and conclusionsIn this review, conventional and dense gas processes of liposomal microencapsulation are evaluated. Comprehensively understanding the current progress of supercritical fluid techniques for liposomal microencapsulation will be helpful for development of a non-toxic continuous process of this application in the food and related industries.     

Liposome Microencapsulation for the Surface Modification and Improved Entrapment of Cytochrome c for Targeted Delivery

In this study, we established a procedure based on the microencapsulation vesicle (MCV) method for preparing surface‐modified liposomes, using polyethylene glycol (PEG) and a site‐directed ligand, with high entrapment efficiency of cytochrome c (Cyt c). For preparing a water‐in‐oil (W/O) emulsion, egg phosphatidylcholine and cholesterol were dissolved in organic solvents (O phase) and emulsified by sonication with aqueous solution of Cyt c (W₁). Although the dispersion stability of the W₁/O emulsion was low when n‐hexane was used to dissolve the lipids in the O phase, it was substantially improved by using mixed solvents consisting of n‐hexane and other organic solvents, such as ethanol and dichloromethane (DCM). The W₁/O emulsion was then added to another water phase (W₂) to prepare the W₁/O/W₂ emulsion. PEG‐ and/or ligand‐modified lipids were introduced into the W₂ phase as external emulsifiers not only for stabilizing the W₁/O/W₂ emulsion but also for modifying the surface of liposomes obtained later. After solvent evaporation and extrusion for downsizing the liposomes, approximately 50% of Cyt c was encapsulated in the liposomes when the mixed solvent consisting of n‐hexane and DCM at a volume ratio of 75/25 was used in the O phase. Finally, the fluorescence‐labeled liposomes, with a peptide ligand having affinity to the vasculature in adipose tissue, were prepared by the MCV method and intravenously injected into mice. Confocal microscopy showed the substantial accumulation of these liposomes in the adipose tissue vessels. Taken together, the MCV technique, along with solvent optimization, could be useful for generating surface‐modified liposomes with high drug entrapment efficiency for targeted delivery.     

Orthogonal array design method for optimization experiments of sodium azide microencapsulation with stearic acid

In this study, an orthogonal array design (OAD), OA₉, was employed as a statistical experimental method for mircoencapsulation of sodium azide with stearic acid through a solvent/non-solvent procedure which is based on the coacervation principle. Scanning electron microscopy (SEM) was used to examine the coating morphology. The effect of stearic acid coating on sodium azide decomposition has been studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC). Our findings revealed that stearic acid can provide an effective coating shell around sodium azide microparticle and the coating quality is affected by some parameters, such as percent of stabilizer, addition time of non-solvent, volume of non-solvent and stirring speed of the mixture (revolutions per minute, rpm). The effects of these factors on the thermal decomposition temperature of microencapsulated sample were quantitatively evaluated by the analysis of variance (ANOVA). The statistical results showed that sodium azide powder can optimally be coated and stabilized by controlling of stabilizer percent, addition time of non-solvent, and volume of non-solvent. The OAD evaluation of initial experimental data provide optimized amount of the parameters to obtain the most stabilized sample, at which the thermal decomposition temperature of sodium azide is predicted at 436 °C. The prediction is in excellent agreement with experimental result obtained at the same conditions that is 435 °C. These data could be compared to that of the pure stearic acid and sodium azide in which decomposition temperature ranges are 160–300 and 382–397 °C, respectively. Also, the kinetic parameters such as activation energy and frequency factor of the decomposition processes of pure components and microencapsulated sodium azide at optimum condition were obtained from the DSC data by non-isothermal methods proposed by ASTM E696. Our finding showed that the treated NaN₃ has much lower decomposition rate as compared to the pure one.     

Physicochemical Characterization of Whole Egg Powder Microencapsulated by Spray Drying

Physical characterization and oxidative stability of egg powder microencapsulated by spray drying were studied in this work. The wall material (gelatin, lactose, pullulan, and their mixtures) and liquid egg mixtures were prepared by homogenization at 22,000 rpm for 60 s. The spray drying was carried out at pilot-scale spray dryer (Niro Mobile Minor, Søborg, Denmark). The spray-dried egg powders were analyzed for moisture content, water activity, peroxide value, total cholesterol oxidation products (TCOPs), particle properties, and bulk properties. Using gelatin as wall material resulted in a significant increase in the moisture content and water activity of egg powder during storage and it improved flowability. Egg powders containing pullulan as wall material showed a fibrous structure and had the lowest bulk density. Adding lactose as wall material increased the oxidative stability, which was indicated with lowest peroxide value and TCOPs level of egg powder.     

Quantifying Trace 2,4,6‐Trinitrotoluene (TNT) in Polymer Microspheres

Well characterized test materials are essential for validating the performance of current trace explosive detection systems. Explosive encapsulated microspheres have proven to be a valuable test material for trace explosive detection because of their precise size, shape, and composition. Presented herein is the quantification of explosives in the polymer microspheres by high performance liquid chromatography with UV/Vis detection (HPLC‐UV/Vis). A size exclusion separation is employed to quantify the amount of explosive encapsulated in cured microspheres. Complete quantification was achieved by simultaneously separating and quantifying the explosive and polymer components. Results indicate that approximately 30 % of the TNT is lost in the manufacturing of the microspheres and subsequent loss from the cured microspheres is minimal if stored at 4 °C.