Synthesis and degradation of agar‐carbomer based hydrogels for tissue engineering applications

Hydrogels studied in this investigation, synthesized starting from agarose and Carbomer 974P, were chosen for their potential use in tissue engineering. The strong ability of hydrogels to mimic living tissues should be complemented with optimized degradation time profiles: a critical property for biomaterials but essential for the integration with target tissue. In this study, chosen hydrogels were characterized both from a rheological and a structural point of view before studying the chemistry of their degradation, which was performed by several analysis: infrared bond response [Fourier transform infrared (FT‐IR)], calorimetry [differential scanning Calorimetry (DSC)], and % mass loss. Degradation behaviors of Agar‐Carbomer hydrogels with different degrees of crosslinkers were evaluated monitoring peak shifts and thermal property changes. It was found that the amount of crosslinks heavily affect the time and the magnitude related to the process. The results indicate that the degradation rates of Agar‐Carbomer hydrogels can be controlled and tuned to adapt the hydrogel degradation kinetics for different cell housing and drug delivery applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

中变质煤结构演化的FT-IR分析

选择5种有代表性的炼焦用煤,分属不同地方不同煤种的中等变质程度煤,在实验室条件下利用美国生产的FTS-165傅立叶变换红外光谱仪对其进行FT-IR分析,采用WIN-IR软件中的谱图解叠子程序针对煤特有的结构性质进行研究。结果表明:煤中存在5种类型的羟基,其与氧碳原子比（O/C）的关系较为复杂;随着煤中氧含量的减少,碳含量的增高,煤中各类脂肪类物质增加,在肥煤阶段达到最大然后减少;煤中含氧官能团的变化趋势为稳定的官能团具有增大的特征,而不稳定的则减少;在肥煤阶段其芳香烃碳-碳双键强度减小,然后又增大;提出在肥煤阶段煤化作用跃变是由于脂肪侧链和芳香体系相互竞争的结果。     

面向存储测试系统的FT245RL数据传输控制器设计

针对传统以单片机和CPLD构建存储测试系统的方案中器件多设计繁琐系统稳定性差的问题,提出了基于单片FPGA的存储测试系统构建方案,在介绍了这一方案的总体设计及工作原理后,重点阐述了以FPGA和FT245RL为核心器件的USB接口电路以及运用有限状态机在FPGA内部实现数据传输控制的方法。最后通过实验对存储测试系统的准确...     

Sensitivity and analysis GPS signals based bridge damage using GPS observations and wavelet transform

This paper uses GPS monitoring system on the Yonghe Bridge. After a year from re-construction of this bridge, cracks were pronounced 48.2 m far from the beginning of the abutment. To analyze the movements of bridge tower, the current operational safety, the cause of bridge cracks and sensitivity of GPS signals, and its movements were observed under different stress factors such as wind speed, temperature change and traffic loads. The observed lateral, longitudinal of bridge’s towers were studied. Two analytical methods namely; DWT and FT were used for the analysis of observation data. The analysis of test results indicates that: (1) The STFT is a significant step forward from the traditional FFT in terms of structural response analysis. (2) The sensitivity of GPS signals does not depend on the position of GPS antenna; and (3) the cracks of bridge deck bring out the frequency of the bridge tower movement transient characteristics.     

Glycidyl methacrylate grafted natural rubber: Synthesis,characterization, and mechanical property

Glycidyl methacrylate (GMA) was grafted onto natural rubber (NR) using emulsion polymerization method. The structures of copolymers were characterized by ¹H nuclear magnetic resonance (¹H‐NMR), solid state ¹³C‐NMR spectroscopy, and Fourier transform infrared spectrometer (FTIR). The %grafting obtained from the gravimetric method and the absorbance ratio were compared. Effects of reaction temperature, GMA content, and reaction time on %grafting, grafting efficiency, and %conversion of GMA monomer were determined. Effect of %grafting on mechanical properties of the graft copolymer was studied. Experimental result showed that the appropriate reaction time was 8 h at a reaction temperature of 30°C. Moreover, tensile strength and modulus of the graft copolymer increased with increasing %grafting. However, elongation at break of the graft copolymer decreased with increasing %grafting. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3152–3159, 2011     

Differentiation of post harvest date fruit varieties non‐destructively using FT‐NIR spectroscopy

The world production of dates has more than doubled over the last two decades. Presently, the industrial sorting of dates is a difficult operation, affected by a high level of losses. As a consequence, the objective of this article is to study the variety discrimination capabilities of Fourier Transform‐Near Infrared (FT‐NIR) reflectance spectroscopy for post‐harvest sorting purposes. The same methodology was tested on six commercial date varieties named Estamaran, Kabkab, Mazafati, Piarom, Deglet nour and Zahedi. For each cultivar, 100 fruits were analysed using the FT‐NIR spectrometer, subsequently characterised by destructive measurements. A multivariate analysis of the FT‐NIR spectra appears a feasible tool for cultivar discrimination and even to estimate the soluble solid content (SSC) and dry matter (DM) of dates at their optimal harvesting conditions. FT‐NIR, as a non‐destructive techniques, could be a suitable way for on‐line screening of different dates varieties.     

Isolation and characterization of pepsin‐solubilized collagen from the integument of sea cucumber (Stichopus vastus)

BACKGROUND: Sea cucumber (Stichopus vastus) is considered an underutilized resource, since only its stomach and intestines are eaten raw as salad in a few countries and the remaining parts, especially the integument rich in collagen, is discarded. Hence a valuable by‐product having potential nutraceutical and pharmaceutical applications is wasted. In the present investigation, pepsin‐solubilized collagen (PSC) from the integument of S. vastus was isolated, purified and characterized. RESULTS: Sodium dodecyl sulfate–polyacrylamide gel electrophoretic analysis showed that the purified collagen was of type I, consisting of three α1 chains of approximately 122 kDa each. The peptide map of PSC digested by V8 protease was different from that of calf skin type I collagen. Fourier transform infrared spectroscopy revealed that the triple helical structure was well preserved in isolated collagen. The denaturation temperature of PSC was 21.23 °C and showed good gel‐forming capability at pH 6.5 and 300 mmol L^?1 NaCl. CONCLUSION: It is inferred that the collagen isolated from S. vastus integument has potential for use as an alternative to land‐based mammalian collagen in food, nutraceuticals and pharmaceutical industries. © 2012 Society of Chemical Industry     

Application of a hydrolyzable cationic agent,poly(acryloxyethyl trimethylammonium chloride), in salt‐free reactive dyeing for good dyeing properties

Poly(acryloxyethyl trimethylammonium chloride) (PAOTAC), in which cationic groups were connected with the polymer skeleton through ester bonds, was applied in the salt‐free reactive dyeing of cotton with the aim of achieving good dyeing properties. Exhaust and exhaust–pad–steam dyeing procedures were used with the cotton cationized with PAOTAC in the absence of salt; for comparison, both dyeing procedures were also applied with the untreated cotton in the presence of salt. The dyeing results show that only the exhaust–pad–steam dyeing procedure was suitable for dyeing cationic cotton to achieve a high dye fixation. Color yields, colorimetric properties, fastness properties, dyeing levelness, and penetration behaviors with different dyeing methods were evaluated. Compared with the dyeings with untreated cotton in conventional exhaust dyeing, dyeings with cationic cotton in the exhaust–pad–steam procedure showed equivalent or even better fastness with generally higher color yields and good dye penetration. Possible reasons for the improved salt‐free dyeing properties were proposed, and the hydrolysis of ester bonds within PAOTAC under the dyeing conditions was proven by IR spectroscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011