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1.
Huang J.  Ni D.  Ni X.  Chen W.  Fu Y. 《丝绸》2022,(12):187-196
Silk is a kind of natural fiber with good luster strength elasticity dyeability hygroscopicity and other advantages. Silk products are quite popular to the customers because of their excellent performance such as heat preservation air permeability and so on which make them comfortable to use. Silk floss which is made from pupa lining secondary cocoon etc. can be used as floc and filler materials and is an important part of silk products. According to its production mode silk floss can be divided into manual silk floss and machine-made silk floss and the latter has become the main processing mode of silk floss production due to its high production efficiency. In terms of composition silk flossing generally contains 20% - 30% sericin pupa oil and impurities so in the degumming process in addition to adding sodium carbonate and other degumming agents to remove sericin a large amount of hydrogen peroxide with strong oxidation property is also used to increase the cleanliness and smoothness. Unfortunately hydrogen peroxide is highly flammable and explosive and poses a risk in transportation and storage causing potential safety hazards to the silk processing industry. In order to solve this problem we innovatively propose two hydrogen peroxide-free processing methods of machine-made silk floss by using sodium percarbonate degumming or sodium carbonate-ozone. As an environmentally friendly solid oxidant sodium percarbonate can produce hydrogen peroxide and sodium carbonate after decomposition and is often used to degrade organic harmful substances. Similarly ozone is a common strong oxidant with broad-spectrum antibacterial properties and because ozone can be produced instantly by ozone generators there is no risk of transport and storage. Silk is composed of silk fibroin and sericin. Among them silk fibroin is fibrous protein which will swell in hot water while sericin is globular protein which is easy to dissolve in hot water. As a result in this paper heated sodium percarbonate solution and sodium carbonate-ozone system were used to deglue silk floss. The methods were as follows silk floss was degummed three times in boiling 0. 78 g / L sodium percarbonate solution for 30 minutes each time or was degummed three times in boiled 0. 5 g / L Na2 CO3 solution with ozone continuously flow at a rate of 100 mg / L - h for 30 minutes each time. After cleaning and drying the degummed silk floss can be obtained. After the experiment the apparent morphology sericin residual efficiency impurity rate compression resilience whiteness and other silk floss quality indexes of the two methods were analyzed and compared with superior machine-made silk floss processed by commercial way with hydrogen peroxide. The results show that both two processing methods got uniform degumming effect of silk floss and the surface of the single fiber was smooth and the degumming effect was basically the same as that of commercial products prepared with hydrogen peroxide. The sericin residual rate of silk floss was between 3% - 4% which was in line with the requirements of less than 5% of superior silk floss. There was no significant difference between silk floss obtained and commercial superior products in smoothness and whiteness. In conclusion the performance of silk floss in all aspects has reached the standard of superior products that is the sericin content is not more than 5% the impurity content is not more than 0. 1% the compression rate is not less than 45% and the response rate is not less than 92% . Based on the experimental results and analysis it can be concluded that the machine-made silk floss with good performance can be prepared without hydrogen peroxide showing the feasibility of processing machine-made silk floss without hydrogen peroxide which is of great significance to the research and development of a safe and reliable oxidant system for the removal of impurities in silk floss and to further improve the safety of machine-made silk floss production process. © 2022 China Silk Association. All rights reserved.  相似文献   
2.
The present article investigates the influence of Joule heating and chemical reaction on magneto Casson nanofluid phenomena in the occurrence of thermal radiation through a porous inclined stretching sheet. Consideration is extended to heat absorption/generation and viscous dissipation. The governing partial differential equations were transformed into nonlinear ordinary differential equations and numerically solved using the Implicit Finite Difference technique. The article analyses the effect of various physical flow parameters on velocity, heat, and mass transfer distributions. For the various involved parameters, the graphical and numerical outcomes are established. The analysis reveals that the enhancement of the radiation parameter increases the temperature and the chemical reaction parameter decreases the concentration profile. The empirical data presented were compared with previously published findings.  相似文献   
3.
文冠果叶提取物降血压活性研究   总被引:1,自引:0,他引:1  
目的:探究文冠果叶提取物对原发性高血压大鼠(SHR)的降血压活性。方法:试验设计为空白对照组(正常血压大鼠)、阳性对照组(SHR大鼠灌胃氨氯地平)、阴性对照组(SHR大鼠)和高、中、低剂量组(SHR大鼠灌胃2,1,0.5 g/kg文冠果叶提取物)。灌胃4周后,观察大鼠收缩压、舒张压、平均压、心率、血清内皮素-1、NO、总胆固醇及甘油三酯等指标。结果表明:灌胃4周后,与阴性对照组相比,高、中、低剂量组SHR大鼠收缩压、舒张压、平均压及血脂均显著降低(P<0.05),中剂量组大鼠的血脂与血清ET-1显著降低,血清NO水平升高(P<0.05),而对SHR大鼠心率和胆固醇无显著影响(P>0.05)。结论:动物体内试验表明文冠果叶提取物可以显著降低SHR大鼠血压,中剂量组效果显著。  相似文献   
4.
Maidebura  Y. E.  Malin  T. V.  Zhuravlev  K. S. 《Semiconductors》2022,56(6):340-345
Semiconductors - The transformation of a two-dimensional GaN layer into three-dimensional islands (2D–3D transition) under increasing temperature in a flow of ammonia is investigated...  相似文献   
5.
Thin-film composite (TFC) membranes are commendable semipermeable barriers for water treatment. Although conventionally immiscible interfaces between aqueous and organic solutions are widely utilized for obtaining TFC membranes, interfacial polymerization still suffers from the issues of harmful solvents, complex diffusion/reaction of the reactants, and thermodynamic and kinetic instability of interfaces. In this study, vapor-phase polymerization with no requirements for organic solvent and immiscible interface is utilized for processing TFC nanofiltration membranes. Through cross-linking of β-cyclodextrin and piperazine layers by trimesoyl chloride vapor, polyester and polyamide TFC membranes with high cross-linking degree are simply prepared in a scalable and reproducible manner. The prepared TFC membranes exhibit stable nanofiltration and desalination performance for all water, organic solvent, and water–organic mixture systems, with permeance up to an order of magnitude higher than that of commercial membranes.  相似文献   
6.
Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics.  相似文献   
7.
8.
Gao  Dongli  Chen  Xingchao  Yang  Xinyu  Tong  Y. O.  Lin  Peng 《Fire Technology》2022,58(1):571-590
Fire Technology - The critical velocity is the minimum velocity blowing towards the fire seat in tunnels to reduce the length of back-layering to zero, and it has been extensively adopted in the...  相似文献   
9.
Journal of Materials Science - A simple route has been developed for the preparation of mesoporous graphitic carbons with embedded cobalt nanoparticles just using glycine as a nitrogen source,...  相似文献   
10.
A strategy for creating potent and pan-genotypic stimulator of interferon genes (STING) agonists is described. Locking a bioactive U-shaped conformation of cyclic dinucleotides by introducing a transannular macrocyclic bridge between the nucleic acid bases leads to a topologically novel macrocycle-bridged STING agonist (MBSA). In addition to substantially enhanced potency, the newly designed MBSAs, exemplified by clinical candidate E7766 , exhibit broad pan-genotypic activity in all major human STING variants. E7766 is shown to have potent antitumor activity with long lasting immune memory response in a mouse liver metastatic tumor model. Two complementary stereoselective synthetic routes to E7766 are also described.  相似文献   
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