Effect of sterilization techniques on the physicochemical properties of polysulfone hollow fibers

Sterilized hollow‐fiber membranes are used in hemodialysis, ultrafiltration, bioprocessing, and tissue engineering applications that require a stable and biocompatible surface. In this study, we demonstrated significant changes in the fiber physicochemical properties with different methods of sterilization. Commercial polysulfone (PS) hollow fibers containing poly(vinyl pyrrolidone) were subjected to standard ethylene oxide (ETO), sodium hypochlorite (bleach), and electron‐beam (e‐beam) sterilization techniques followed by analysis of the surface hydrophilicity, morphology, and water‐retention ability. E‐beam sterilization rendered more hydrophilic fibers with water contact angles near 47° compared to the ETO‐ and bleach‐treated fibers, which were each near 56°. Atomic force microscopy revealed lumen root mean square (rms) roughness values near 19 nm for all three sterilization methods; however, e‐beam‐sterilized and bleach‐treated fibers had significantly higher (～ 106 nm) rms values for the outer wall compared to the ETO‐sterilized fibers (～ 39 nm). The increased hydrophilicity and surface area of the e‐beam‐sterilized fiber were reflected by a greater water evaporation rate than that of the ETO‐treated fiber. These results demonstrate that common sterilization methods may significantly and distinctly alter the polymer membrane physicochemical properties, which may, in turn, impact the performance and, in particular, surface fouling. For tissue engineering and bioprocessing applications, these changes may be leveraged to promote cell adhesion and spreading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Use of multiple regression analysis to develop predictive models for failure times of adhesive bonds at constant stress

Predictive models were developed for failure times of adhesively bonded titanium and aluminum under a constant stress. The independent variables in the equations were temperature, relative humidity, and stress. The predictive equations were developed using multiple regression analysis which was performed by computer. A comparison of actual failure times with those predicted by the models gave at least an order-of-magnitude agreement. A previously developed reaction rate model was also verified by regression techniques.     

A new mode of fear expression: Perceptual bias in height fear.

Emotion and psychopathology researchers have described the fear response as consisting of four main components--subjective affect, physiology, cognition, and behavior. The current study provides evidence for an additional component in the domain of height fear (perception) and shows that it is distinct from measures of cognitive processing. Individuals High (N = 35) and Low (N = 36) in acrophobic symptoms looked over a two-story balcony ledge and estimated its vertical extent using a direct height estimation task (visual matching), and an indirect task (size estimation); the latter task seems to exhibit little influence from cognitive factors. In addition, implicit and explicit measures of cognitive processing were obtained. Results indicated that, as expected, the High Fear group showed greater relative, implicit height fear associations and explicit threat cognitions. Of primary interest, the High (compared to Low) Fear group estimated the vertical extent to be higher, and judged target sizes to be greater, even when controlling for the cognitive bias measures. These results suggest that emotional factors such as fear are related to perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

第一名无边界花园

花园是否需要可见的边界呢?它与周边环境之间的过渡能否以其他方式来实现?一位牧师和她的丈夫在修建他们花园的时候不得不面对这些问题.现在花园已经建成,修剪整齐的角树为花园划定明确界限,让其与周围的田地自然地融合在一起.在花园的东面,密集的角树很好地保护花园的私密性.春暖花开之时,草地上随处可见水仙和牡丹;金秋送爽之际,番红花为草地换上新衣裳.宽敞的草坪是人们散步休闲的好去处.车棚的后墙爬满蔷薇.房子前方的沙砾地上放置着七个圆顶岗亭.角树形状和岗亭的数量具有宗教象征意义.     

第三名男爵花园极简主义风景园

这座新建的避暑农舍傲然耸立在石质裙房之上,远远望去像是花园的围墙. 花园糅合了瑞典南部村舍的直线型建筑风格,简约却不失当代气息.斯卡那地区典型农场为这座农舍的比例设计、材质选择和建筑平面以及花园严谨的几何图案设计带来灵感,让它与周围的风景相互呼应. 作为农舍典型元素的庭院,铺满了冰块形鹅卵石,外围和门槛内外则采用花岗岩铺装.一株孤植日本山茱萸为小庭院带来阵阵荫凉.     

文化风景园

花园还是乡村的文化景观?若不是因为东斯提利亚乡村边上那现代的透明建筑,这个问题可能很难回答。一面由玄武岩堆砌而成的干石墙连接着房子和附属建筑,它们之间设有一个花园式庭院,里面种有三棵喜马拉雅白桦树。干石墙是当地文化景观的一部分,同样的,独立式的辅助构筑是传统农舍的一部分。一条散步道通向入口;房间的正面全是落地玻璃,让人们在室内就可将远方的风景尽收眼底。黑色的石头从内部一直延伸到台地上。紧挨着观景木台的内凹私密园地里种有柳树。在房子周围还能发现更多的奥地利文化景观,落叶松制成的花园栅栏,勾起人们对田园生活的回忆。观景木台和     

High‐Performance Multifunctional Graphene‐PLGA Fibers: Toward Biomimetic and Conducting 3D Scaffolds

The development of electrically conducting fibers based on known cytocompatible materials is of interest to those engaged in tissue regeneration using electrical stimulation. Herein, it is demonstrated that with the aid of rheological insights, optimized formulations of graphene containing spinnable poly(lactic‐co‐glycolic acid) (PLGA) dopes can be made possible. This helps extend the general understanding of the mechanics involved in order to deliberately translate the intrinsic superior electrical and mechanical properties of solution‐processed graphene into the design process and practical fiber architectural engineering. The as‐produced fibers are found to exhibit excellent electrical conductivity and electrochemical performance, good mechanical properties, and cellular affinity. At the highest loading of graphene (24.3 wt%), the conductivity of as‐prepared fibers is as high as 150 S m^?1 (more than two orders of magnitude higher than the highest conductivity achieved for any type of nanocarbon‐PLGA composite fibers) reported previously. Moreover, the Young's modulus and tensile strength of the base fiber are enhanced 647‐ and 59‐folds, respectively, through addition of graphene.     

Ethical Observations on the Choice of Parenteral Solvents

The parenteral administration of insoluble drugs leads to the use of biologically active solvents inducing effects associated with ethical cause of concern including pain and pharmacological interactions. Selected vehicles currently used were ethically and scientifically reviewed. Our investigations allowed reinforcing the formulation decision tree with an ethical point of view. The last generation of cyclodextrin appears to be the safest solvent. Second choice could be lipidic emulsions, third choice being co-solvents, and finally non-ionic surfactants because of their hypersensitivity reactions. Screening tests including pH, osmolality measurements, cytotoxicity, and hemotoxicity, should allow to check the formulation tolerance before the animals' administration.     

The effect of water suppression on the hepatic lipid quantification,as assessed by the LCModel,in a preclinical and clinical scenario

Objective

To investigate the effect of water suppression on the hepatic lipid quantification, using the LCModel.

Materials and methods

MR spectra with and without water suppression were acquired in the liver of mice at 4.7 T and patients at 3 T, and processed with the LCModel. The Cramér–Rao Lower Bound (CRLB) values of the seven lipid resonances were determined to assess the impact of water suppression on hepatic lipid quantification. A paired t test was used for comparison between the CRLBs obtained with and without water suppression.

Results

For the preclinical data, in the high (low) fat fraction subset an overall impairment in hepatic lipid quantification, i.e. an increase of CRLBs (no significant change of CRLBs) was observed in spectra acquired with water suppression. For the clinical data, there were no substantial changes in the CRLB with water suppression. Because (1) the water suppression does not overall improve the quantification of the lipid resonances and (2) the MR spectrum without water suppression is always acquired for fat fraction calculation, the optimal data-acquisition strategy for liver MRS is to acquire only the MR spectrum without water suppression.

Conclusion

For quantification of hepatic lipid resonances, it is advantageous to perform MR spectroscopy without water suppression in a clinical and preclinical scenario (at moderate fields).