Semi-empirical systematics of (n,He-3) cross sections for 14.6 MeV neutrons

A new semi-empirical formula for the calculation of the (n, He-3) cross section at 14.6 MeV neutron energy is obtained. It is based on the evaporation model. The new formula with three parameters is found to give a better fit to the data than the previous comparable formulae.     

Study of processing parameters influencing the properties of Diltiazem hydrochloride microspheres

Diltiazem hydrochloride-ethylcellulose microspheres were prepared by the water-in-oil emulsion-solvent evaporation technique. Small and spherical microspheres having a mean microsphere diameter in the range of 40-300 µm and entrapment efficiency of ~60-90% were obtained. Scanning electron micrographs of drug-loaded microspheres showed the presence of uniformly distributed small pores and absence of drug crystals on their surface, indicating simultaneous precipitation of drug and the polymer from the solvent during solvent evaporation. Differential scanning calorimetric analysis confirmed the absence of any drug-polymer interaction. The in vitro release profile could be altered significantly by changing various processing parameters to give a controlled release of drug from the microspheres. The stability studies of the drug-loaded microspheres showed that the drug was stable at storage temperatures, 5-55°C, for 12 weeks.     

HPLC测定刺蒺藜总皂苷中的薯蓣皂苷元

目的测定刺蒺藜总皂苷水解后薯蓣皂苷元的含量。方法采用ELSD-HPLC法,并考察其方法学。结果薯蓣皂苷元39.68~942μg.ml-1与峰面积的线性关系良好,方法具有较好的精密度、稳定性、重复性和较高的回收率。结论所建方法准确、简便、易行,可作为刺蒺藜总皂苷的质量控制指标。     

样品自动防蒸发保存系统研究与应用评价

目的　为防止样品待检时的蒸发浓缩 ,研制了样品自动防蒸发保存系统 (已获国家专利 ) ,并对应用效果进行评价。方法　用自动控制的加湿装置使封闭的系统内水蒸汽迅速达到并维持饱和状态 ,起到防蒸发效果。用蒸馏水及混合血清样品分别在该系统内、外存放 ,检测存放前后蒸馏水的重量及混合血清K、Na、Cl、TP、Alb的含量。结果　蒸馏水样品在该系统内、外存放 2 4h ,0 .5ml和 1.5ml样品杯的平均蒸发率差异均有非常显著性 (P <0 .0 1)。混合血清在该系统内、外存放 2、4、8、16、2 4h ,0 .5ml样品杯和 1.5ml样品杯的平均蒸发率差异均有非常显著性 (P <0 .0 1)。结论　样品自动防蒸发保存系统可防止待检样品蒸发浓缩 ,提高检测结果正确性。     

2020年IAEA比对样品中总α和总β放射性分析

目的:对2020年国际原子能机构(IAEA)比对样品中总α和总β放射性测量实践进行总结,以期对同类测量提供参考。方法:按照比对要求,薄层法分别以 241Am、总Th、 90Sr/ 90Y、 40K和 137Cs溶液为标准源,测定水样、气溶胶样品中总α和总β放射...     

Formulation and characterization of azidothymidine-loaded liposomes

Entrapment efficiency (EE%) and in vitro stability of azidothymidine (AZT)-loaded hand-shaken multilamellar vesicles (MLVs), freeze and thaw vesicles (FATMLVs), and reverse phase evaporation vesicles (REVs) were compared. AZT entrapment in FATMLVs was further studied by varying initial lipid concentrations, drug concentration, and lipid composition. The results suggest that AZT entrapment is dependent on the aqueous volume entrapped within liposomes, and the interaction between the drug and liposomal bilayer may not be significant. Increasing the lipid concentration increases the liposomal entrapment of AZT but the encapsulation yield decreases above a lipid concentration of 30 μmol/mL. No significant difference was observed in EE% when the AZT concentration was varied from 5 to 20 mg/mL. The entrapment efficiency was highest (43.2%) for DSPC/CHOL/PS (molar ratio 6:3:3) vesicles but DSPC/CHOL/PS liposome formulations in a molar ratio of 4:3:3 or 4:5:1 and DSPC/CHOL/SA liposome formulations in a molar ratio of 4:5:1 were found to be more stable in vitro. In vitro drug release from liposomes was dependent on bilayer composition and the method of preparation.     

Statistical Approaches to Assessing Single and Multiple Outcome Measures in Dry Eye Therapy and Diagnosis

Dry eye is a multifactorial disease which would require a broad spectrum of test measures in the monitoring of its treatment and diagnosis. However, studies have typically reported improvements in individual measures with treatment. Alternative approaches involve multiple, combined outcomes being assessed by different statistical analyses. In order to assess the effect of various statistical approaches to the use of single and combined test measures in dry eye, this review reanalyzed measures from two previous studies (osmolarity, evaporation, tear turnover rate, and lipid film quality). These analyses assessed the measures as single variables within groups, pre- and post-intervention with a lubricant supplement, by creating combinations of these variables and by validating these combinations with the combined sample of data from all groups of dry eye subjects. The effectiveness of single measures and combinations in diagnosis of dry eye was also considered.     

Preparation and characterization of hCG-loaded polylactide or poly(lactide-co-glycolide) microspheres using a modified water-in-oil-in-water (w/o/w) emulsion solvent evaporation technique

A modified w/o/w emulsion solvent evaporation technique was adopted to prepare human Chorionic Gonadotropin (hCG)-loaded polylactide (PLA) or poly(lactide-co-glycolide) (PLGA) microspheres. The effects of preparative parameters, such as stirring rate, polymer MW and concentration, and the composition of both the inner aqueous phase and oil phase etc., on hCG entrapment efficiency and microsphere characteristics were investigated. It was found that by adding 20% glycerol into the inner aqueous phase and 40% acetone into the oil phase, smooth microspheres 1mum in diameter could be produced with high hCG entrapment efficiency (&gt;90%). In vitro release test showed a burst release of hCG from PLGA (75:25) microspheres, followed by sustained release of 55% hCG over 2 months. The initial hCG burst from PLGA microspheres increased with the glycerol concentration in the inner aqueous phase, but decreased to a low value (ca. 20%) with the addition of acetone into the oil phase, which could beattributed to the associated changes in surface morphology of the microspheres. In vivo experiments demonstrated that a single shot of hCG-loaded PLGA microspheres could produce a comparable antibody response with the inoculation of free hCG four times.     

Magnetite (Fe 3 O 4) microcapsules prepared using a glass membrane and solvent removal

Fine magnetite powders dispersed in polymer solution were encapsulated from an oil-in-water emulsion prepared by an emulsification process employing a porous glass membrane and subsequent evaporation of the solvent. Styrenebased copolymers were dissolved in a magnetic fluid, and then continuously pushed through the pores of glass membrane into the aqueous phase, which had dissolved polyvinyl alcohol (PVA) and sodium dodecyl sulphate (SDS) as a mixed stabilizer. P(styrene-co-acrylic acid) (PS-AA), P(stryrene-co-butyl acrylate) (PS-BA) and styrene-butadiene rubber (SBR) were dissolved in the specially ordered magnetite fluid (25 wt% magnetite dispersed in toluene) separately or as a mixture, and uniform droplets suspending the magnetic particles were obtained. After the evaporation of toluene, PS-AA capsules retained a spherical shape and uniformity, whereas PS-AA/PS-BA capsules revealed a creased surface and broader size distribution. The microcapsules entrapped 30-40 wt% of magnetite, and the encapsulation yield of magnetite was 20-40%. Glass membranes with 9.5, 5.25 and 1.42 #119 m pore size were employed and 5-40 #119 m microcapsules were obtained depending on the pore size. When magnetite suspended in chloroform was used, magnetite capsules with broader size distributions were obtained because of the sticking of the droplets to the membrane wall. The advantage of the membrane emulsification which provides uniform sized droplets was lost.     

Interactions of polar lipids with cholesteryl ester multilayers elucidate tear film lipid layer structure

PurposeThe tear film lipid layer (TFLL) covers the tear film, stabilizing it and providing a protective barrier against the environment. The TFLL is divided into polar and non-polar sublayers, but the interplay between lipid classes in these sublayers and the structure-function relationship of the TFLL remains poorly characterized. This study aims to provide insight into TFLL function by elucidating the interactions between polar and non-polar TFLL lipids at the molecular level.MethodsMixed films of polar O-acyl-ω-hydroxy fatty acids (OAHFA) or phospholipids and non-polar cholesteryl esters (CE) were used as a model of the TFLL. The organization of the films was studied by using a combination of Brewster angle and fluorescence microscopy in a Langmuir trough system. In addition, the evaporation resistance of the lipid films was evaluated.ResultsPhospholipids and OAHFAs induced the formation of a stable multilamellar CE film. The formation of this film was driven by the interdigitation of acyl chains between the monolayer of polar lipids and the CE multilayer lamellae. Surprisingly, the multilayer structure was destabilized by both low and high concentrations of polar lipids. In addition, the CE multilayer was no more effective in resisting the evaporation of water than a polar lipid monolayer.ConclusionsFormation of multilamellar films by major tear film lipids suggest that the TFLL may have a similar structure. Moreover, in contrast to the current understanding, polar TFLL lipids may not mainly act by stabilizing the non-polar TFLL sublayer, but through a direct evaporation resistant effect.