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1.
Self-assembly of soy proteins into nanofibrils is gradually considered as an effective method to improve their technical and functional properties. Ultrasound is a non-thermal, non-toxic and environmentally friendly technology that can modulate the formation of protein nanofibrils through controlled structural modification. In this research, the effect of ultrasound pretreatment on soy protein isolate nanofibrils (SPIN) was evaluated by fibrillation kinetics, physicochemical properties and structure characteristics. The results showed that the optimum ultrasound condition (20% amplitude, 15 min, 5 s on-time and 5 s off-time) could increase the formation rate of SPIN by 38.66%. Ultrasound reduced the average particle size of SPIN from 191.90 ± 5.40 nm to 151.83 ± 3.27 nm. Ultrasound could increase the surface hydrophobicity to 1547.67 in the initial stage of nanofibrils formation, and extend the duration of surface hydrophobicity increased, indicating ultrasound could expose more binding sites, creating more beneficial conditions for nanofibrils formation. Ultrasound could change the secondary and tertiary structure of SPIN. The reduction of α-helix content of ultrasound-pretreated soy protein isolate nanofibrils (USPIN) was 12.1% (versus 5.3% for SPIN) and the increase of β-sheet content was 5.9% (versus 3.5% for SPIN) during fibrillation. Ultrasound could accelerate the formation of SPIN by promoting the unfolding of SPI, exposure of hydrophobic groups and formation of β-sheets. Microscopic images revealed that USPIN generated a curlier and looser shape. And ultrasound reduced the zeta potential, free sulfhydryl groups content and viscosity of SPIN. SDS-PAGE results showed that ultrasound could promote the conversion of SPI into low molecular weight peptides, providing building blocks for the nanofibrils formation. The results indicated that ultrasound pretreatment could be a promising technology to accelerate SPIN formation and promote its application in food industry, but further research is needed for the improvement of the functional properties of SPIN. 相似文献
2.
M. López Lorenzo V. A. Nierstrasz M. M. C. G. Warmoeskerken 《Cellulose (London, England)》2009,16(1):103-115
The nature of recycled paper fibres varies widely. Those fibres contain high amounts of heteroxylans and lignin besides cellulose.
In order to study the potential effect of xylanases on the quality of recycled fibres, chemithermomechanical pulp fibres (CTMP)
are used as model substrates owing to their high content in non-cellulosic components. It has been found that the morphology
of CTMP fibres changes by means of xylanase treatment. Treatments of CTMP fibres with an endoxylanase result in an improved
surface area of the fibres by fibrillation, without shortening the fibres. The chemical composition of the surfaces of the
fibres changes and an augment in surface hydrophilicity as a result of the removal of lignin and extractives associated to
the xylan backbones is observed. Experimental results are in agreement with the findings when studying the chemical composition
of the fibres’ surfaces: the xylan backbone is removed by the action of the endoxylanase, resulting in fibre fibrillation;
further hydrolysis of released xylan chains proceeds in the bulk down to the monomer xylose. 相似文献
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Bi-functional reactive dyes have been used for reducing the fibrillation of lyocell fibres. The sole influence of CI Reactive
Black 5 dye on the fibrillation tendency of lyocell single jersey knitted fabrics was investigated by dyeing with different
concentrations (35 g/L for medium shade and 70 g/L for dark shade), dyeing without dyestuff and by decolouration process after
each dyeing. The fibrillation tendency of lyocell fibres was accessed by means of fibre wet abrasion resistance and fibrillation
number. Nitrogen content was used as indication of the amount of reactive dye in fabrics during dyeing and decolouration processes.
The correlation between fibre fibrillation tendency and colour values of fabrics was found. Due to the fibrillation reduction,
pilling formation in dyed lyocell fabrics was improved. As colour values can estimate the dye fixation and reduction in fabrics,
reactive dye can be used as a visible marker for crosslinking effect on lyocell fabrics. 相似文献
5.
A procedure for splitting of a lyocell fiber into a multitude of finer fibrils was developed. Crockmeter, usually used for rub-fastness of colored textiles, was modified and used for obtaining required shear force on swollen lyocell fiber. The shear force applied on fibers, and the concentration of NaOH, which affects swelling degree of fiber, were shown to be the leading parameters determining split number of lyocell fiber. While number of shear cycles was found to be of minor relevance for fiber splitting, the applied pressure directly influences the number of splitted fibrils. For example, at a pressure of 34.8 kPa, the average split number of lyocell fiber in 2.5 M NaOH solution was observed as 15, whereas it was observed as 30 for 47 kPa and 41 for 59.3 kPa. Splitting was not observed above 5 M of NaOH solution. Analyses of fiber splitting permit new aspects to study inner structure of lyocell. 相似文献
6.
利用原子力显微镜、傅里叶变换红外光谱仪和荧光光度计等研究了硫硒化镉纳米颗粒对胰高血糖素聚集的影响, 包括聚集形成纤维数量的多少、纤维的生长速度等. 结果表明: 硫硒化镉纳米颗粒能够抑制胰高血糖素多肽的聚集, 并且随着颗粒浓度的增加, 其抑制胰高血糖素维化的程度也明显加剧. 另外, 还对纳米颗粒抑制胰高血糖素聚集的机理进行了初步讨论. 相似文献
7.
Effect of melt viscosity of polypropylene on fibrillation of thermotropic liquid crystalline polymer in in situ composite film 总被引:1,自引:0,他引:1
Various grades of polypropylene were melt blended with a thermotropic liquid crystalline polymer, a block copolymer of p-hydroxy benzoic acid and ethylene terephthalate (60/40 mole ratio). The blends were extruded as cast films at different values
of draw ratio (slit width/film thickness). Fibrillation of TLCP dispersed phase with high fiber aspect ratio (length/width)
was obtained with the matrix of low melt flow rate, i.e., high viscosity and with increasing film drawing. Melt viscosities
of pure components and blends measured using capillary rheometer were found to decrease with increasing shear rate and temperature.
Viscosity ratios (dispersed phase to matrix phase) of the systems being investigated at 255 °C at the shear rate ranged from
102 to 104 s−1, were found to lie between 0.04 and 0.15. The addition of a few percent of elastomeric compatibilizers; a tri-block copolymer
SEBS, EPDM rubber and maleated-EPDM, was found to affect the melt viscosity of the blend and hence the morphology. Among these
three compatibilizers, SEBS was found to provide the best fibrillation.
Received: 10 January 2000/Accepted: 24 January 2000 相似文献
8.
通过圆二色谱分析研究了PEG-醛修饰胰岛素产物在溶液中的构象变化,采用加速振荡实验研究了PEG化对胰岛素纤维化的影响,以体外酶解实验考察了PEG-醛修饰胰岛素产物的抗酶解能力.结果表明,经PEG-醛修饰可以减少胰岛素单体的自缔合,提高胰岛素在溶液中的稳定性,抑制胰蛋白酶和糜蛋白酶对胰岛素的降解. 相似文献
9.
Wangsun?Zhang Satoko?OkubayashiEmail author Thomas?Bechtold 《Cellulose (London, England)》2005,12(3):267-273
The fibrillation tendencies of various cellulosic fibers in aqueous solution containing alkali metal hydroxide and ethanol
were evaluated with two specific parameters: the critical point of fibrillation (CPFconc.), that is a concentration of swelling agent where the fibrillation begins, and the ratio of initial increase in fibril number
to increase in concentration of swelling agent (Ii). The CPFconc. and the Ii are defined as fibrillation stability and fibrillation sensitivity to swelling agent, respectively. Lyocell fiber (CLY1)
has the smallest CPFconc. and the largest Ii, representing the lowest fibrillation stability and the highest fibrillation sensitivity, leading to the highest fibrillation
tendency in CLY1 among the fibers tested. Although crosslinking improved fibrillation stability in lyocell as compared to
modal, the fibrillation stability remained higher owing to the high water capacity and the high affinity for alkali. In alkali
solution at the same concentration CLY1 fibrillation increased in the order of LiOH > NaOH > KOH. However, the plot of fibril
number against solvent retention value of CLY1 in different alkaline solutions gives a slope of 110 count · g/cm3 regardless of alkali type, the critical degree of swelling for CLY1 with no fibrillation was 0.62 cm3/g in alkali solutions and 0.45 cm3/g in ethanol/water mixture. 相似文献
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