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关键词： XLPE insulation   Degassing treatment   Space charge   Material testing   Electrical testing  

摘要： An optimal degassing treatment duration for the preparation of commercial 500 kV extra high voltage direct current (EHVDC) cross-linked polyethylene (XLPE) insulation can improve its overall properties, reduce the manufacturing cost and time, which is urgently needed for high voltage cables suppliers. This paper analyzes the effect of different degassing duration on the content of cross-linking by-products, morphological structure and insulation properties of 500 kV EHVDC XLPE insulation. The raw pellets of commercial 500 kV EHVDC XLPE cable material are used to prepare the test samples by the hot-pressing method. Five samples with the different degassing durations of 0 h, 12 h, 36 h, 90 h, and 200 h were at 70 degrees C. Physico-chemical and electrical methods are used to characterize the overall properties of the material under the different degassing durations. The results show that the measured content of the crosslinking by-products is consistent with the theoretical values calculated by Fick's second law. The oxidation induction time of the samples is reduced and tensile properties are improved with the increase of the degassing time. Furthermore, degassing treatment increased the lamellae thickness in the early stages and reduced the difference in the internal aggregation structure of the material. It was found that the degassing treatment significantly suppressed the space charge accumulation inside the material. Moreover, the degassing treatment of 36 h can increase the dielectric breakdown strength and reduce the current density of the samples. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Wool   Protein-based carbon fiber   Thermal stabilization   Stabilization reactions  

摘要： Natural fibres constitute interesting, low cost and environmentally friendly precursors of carbon fibres. However, they are prone to fuse and degrade upon thermal treatment, affecting the properties of the products unless a stabilization step was included. Aiming to reach a better understanding of the stabilization mechanism of wool as a potential precursor for the preparation of carbon fibres, in this study we have analysed the chemical, structural and morphological transformations during its oxidative stabilization in air. Below 400 ?C, both the structure and morphology of the fibres were preserved. The chemical composition changed with the stabilization temperature;main changes include the loss of secondary protein structure, cleavage of sulphur bridges, dehydration, oxidative crosslinking and rearrangements of N-groups through the formation of carbodiimides. Oxidation of the wool at 300 ?C rendered materials with a fibrous morphology and high carbon yield (ca. 36 wt%), yielding carbon fibres upon carbonization at high temperatures.

关键词： American ginseng   Continuous cropping obstacle   Soil microbial communities   Enzymatic activity  

摘要： Aims In the production of the natural medicinal plant American ginseng, replantation typically fails due to continuous cropping obstacles. However, the cause is still not clear and needs more research. Methods Soil samples were collected from (a) maize fields where American ginseng had never been planted, (b) fields where American ginseng had just been harvested, and (c) fields where maize had been planted for 2, 4 and 6 years respectively after American ginseng. We investigated the physicochemical properties, the enzymatic activities, and the soil microbial community structure and composition of the samples. Results We found that the content of soil salt, NH4+-N, and NO3--N increased significantly in samples associated with the production of American ginseng, whereas the soil pH, carbon-to-nitrogen ratio, alkaline phosphatase, and cellulase activity all significantly decreased and gradually recovered to the pre-planting level. Moreover, the bacterial diversity decreased, while fungal diversity and richness increased;fungal richness continued to increase in farmlands replanted maize. The relative abundance of some microbial communities was changed significantly and was gradually restored with a longer time to replant maize. Pearson's correlation analysis shown that significantly changed microbial communities were significantly associated with changes in soil pH, soil salt and nitrogen content, alkaline phosphatase, and cellulase activity. Conclusions Changes in soil pH, soil salt and nitrogen content caused changes in microbial community structure and composition, as well as cellulase and alkaline phosphatase activity. These changes may cause the continuous cropping obstacles of American ginseng and may be improved by planting maize.

关键词： Irradiation dose   Finger millet   Physicochemical characteristics   Microstructural characteristics   Functional characteristics  

摘要： The present study deals with the effect of irradiation dose on the physico-chemical, functional, proximate and microstructural characteristics of finger millet (CO14 and CO15) slurry flours. The finger millet varieties CO14 and CO15 were made into a slurry, filtered and irradiated using 60CO as a radiation source at various doses from 2.5 kGy to 10 kGy. The samples were dried, powdered and analysed for its quality characteristics. The results revealed that both finger millets varieties significantly differed in the aspects of the swelling index, pH, total phenols, total tannins, proximate composition. The bulk density, swelling index, total phenolic content, total tannin, and lightness (L*) of sample flours reduced insignificantly (P ? 0.05) with the increase in irradiation dose and the water & oil absorption capacity, solubility index, pH, total flavonoids, redness (a*) and blueness (b*) were increased. The protein, ash and fat content of the CO14 and CO15 sample flours showed significant difference at higher dose values (10 kGy). The FTIR-spectra and SEM images exhibited the structural modifications of the sample flour by the irradiation dose. The reduced antinutrients and increased functional properties suggest that the irradiation of millet slurry (<10 kGy) could be utilized as a pre-treatment in the development of milletbased value added food products.

关键词： Sensory properties   Water activity   Freeze pre-drying   Expansion ratio   Crispness  

摘要： The effect pre-drying method in terms of freeze (FD), hot air (HD), and microwave drying (MD), moisture content of turkey breast meat (50%, 40%, 30%, w.b.) prior to puff drying and pre-drying conditions following pressure (15, 20, 25 Pa) for FD, air temperature (65, 70, 75 degrees C) for HD and power (180, 360, 540 W) for MD was evaluated on puff dried turkey breast meat. Samples that dried with different pre-drying and puff drying were examined physically (moisture content, water activity, bulk density and color properties), chemically (salt, fat, protein and TBARS), texturally (crispness, expansion and rehydration ratio, macro and micro structure, mean pore diameter) sensorially (color, puffing degree, hardness, elasticity, crispness, taste, overall impression). The freeze pre-drying method exhibited smaller porous structure and resulted in low moisture content, water activity, bulk density, high expansion and rehydration ratio after puff drying. The hot air pre-dried samples had larger pore diameters and high elasticity because of higher moisture content and water activity values. The mean pore diameter of the microwave pre-dried products did not affect the rehydration and expansion ratio. Generally, the results showed that freeze pre-drying till 50% moisture content at 20 Pa pressure was the most suitable method.

关键词： Biomass   Three main components   Pyrolysis   ZSM-5   Coke  

摘要： Catalytic fast pyrolysis of biomass is an effective strategy for the preparation of high value-added liquid fuels or chemicals. Understanding the effects of different biomass materials on the physicochemical property changes of ZSM-5 is important for the design of modified catalysts and targeted regulation of products. In this study, the catalytic upgrading of lignocellulosic biomass over ZSM-5 was investigated. Lignin, cellulose and xylan were used as model compounds of lignocellulosic biomass, and the upgraded products were analyzed online. Several techniques were used to gain a deep understanding of the physiochemical changes in ZSM-5. The results showed that the addition of ZSM-5 contributed to the production of aromatic hydrocarbons and olefins. The crystal structure and morphology of ZSM-5 were not changed, but the total acid, Bronsted and Lewis acid contents decreased. The amount of coke deposited on ZSM-5 follows the order cellulose/ZSM-5 > xylan/ZSM-5 > lignin/ ZSM-5. Coke on cellulose/ZSM-5 has the lowest H/C ratio of 0.50. Coke on ZSM-5 will create new micropores and increase the specific surface area of micropores.

关键词： Acanthopanax brachypus   water-soluble polysaccharides   ultrasound-assisted extraction   response surface methodology   physicochemical property   structural and functional properties   functional additives  

摘要： The ultrasound-assisted extraction (UAE) parameters of total water-soluble polysaccharides (TABPs) from Acanthopanaxbrachypus fruit were optimized by Box-Behnken design (BBD) and response surface methodology (RSM). Physicochemical, structural, and functional properties of TABPs were investigated by chemical analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), water-holding capacity (WHC), oil-holding capacity (OHC), emulsion capacity (EC), emulsion stability (ES), as well as DPPH. and ABTS(.+)scavenging assays. The results showed that the maximal UAE-yield of TABPs was 3.81 +/- 0.18 % under the optimal conditions (ultrasonic power 325 W, extraction temperature 47 degrees C, extraction time 22 min). TABPs was rich in some beneficial element (Mg, K, Fe, Zn and Na) but little in harmful elements (Hg, Cd, As and Pb), and displayed rough surface with flake-like features and large dents, contained 93.89 +/- 0.08 % of total carbohydrate with more different monosaccharides including glucose, galactose, rhamnose, arabinose, mannose, xylose, and uronic acid in a molar ratio of 8.83 : 7.90 : 4.74 : 4.55 : 2.80 : 2.39 : 1.00, respectively. TABPs exhibited broad weight distribution (11.2-133.5 kDa), excellent thermal stability (>280 degrees C), WHC (0.61 +/- 0.08 g water/g sample) and OHC (4.53 +/- 0.12 g oil/g sample), as well as higher EC (43.75 +/- 1.23 %) and ES (38.32 +/- 1.50 %). Furthermore, TABPs also displayed remarkable scavenging activities on DPPH. and ABTS(.+) in vitro. These findings provide a scientific basis for the applications of TABPs in functional additives for food, medicine, and cosmetics.

关键词： microbial transglutaminase   physicochemical properties   soymilk   tofu gel   ultrasound pretreatment  

摘要： Tofu prepared by conventional methods often has a bitter taste and poor water-holding capacity (WHC). To improve the quality of the product, alternative processes must be developed. Herein, the effect of ultrasound pretreatment on the properties of soymilk and tofu gel derived thereof were investigated. Treatment of soymilk with ultrasound gave rise to a reduction in the particle size and an enhancement in the surface hydrophobicity, whereby optimum values were obtained after 15 min treatment. Subsequently, microbial transglutaminase (MTG) was added to ultrasound-treated soymilk to promote the soy protein crosslinking. The gel strength, WHC, and nonfreezable water content of MTG-catalyzed tofu gel obtained from treated soymilk increased with the extension of the ultrasound pretreatment time, whereas the free sulfhydryl content decreased because of the formation of disulfide bonds. Fourier transform infrared spectroscopy demonstrated variations in the secondary structure of MTG-catalyzed tofu gel. Furthermore, soymilk's exposure to high-intensity ultrasound pretreatment led to a tofu gel with a dense, homogenous, and stable network structure, as evidenced by scanning electron microscopy. Therefore, this study answers for the theoretical support of the industrial production of MTG-catalyzed tofu gel from ultrasound-treated soymilk. Practical Application High-intensity ultrasound pretreatment improved the texture properties of MTG-catalyzed tofu gel. The resulting MTG-catalyzed tofu gel has potential application in industrial production.

关键词： Ions release   Alkalizing activity   Microtensile bonding strength   Nanoleakage   Bioactive glass   Mechanical properties   Self-etching adhesive systems   Bioactivity  

摘要： Objective. The aim of study was to develop and characterize experimental bioactive glasses (45S5 and niobophosphate bioactive glass (NbG)) and evaluate the effects of their addition in self-etching adhesive systems on physicochemical, mechanical, and bioactive properties, microtensile bond strength (& micro;TBS), and nanoleakage (NL). Methods. Two-step self-etching adhesive systems containing 5, 10, and 20 wt.% of 45S5 and NbG bioactive glasses were developed. An experimental adhesive without microparticles and a commercial adhesive (Clearfil SE Bond) were used as control groups. The materials were evaluated for their degree of conversion (DC%), ultimate tensile strength (UTS), soft -ening in solvent, radiopacity, sorption and solubility, alkalizing activity (pH), ionic release, and bioactivity. & micro;TBS and NL were evaluated after 24 h and 1 year of storage. The data were subjected to analysis of variance and post-Holm-Sidak tests ( = 0.05). Results. The addition of the two bioactive glasses did not change the values of the degree of conversion, ultimate tensile strength, and softening in solvent. The adhesive system containing 20% NbG showed the highest radiopacity. The incorporation of 45S5 increased water sorption and solubility, raised the pH, and allowed the release of large amounts of calcium. After 28 days of immersion in simulated body fluid, the 45S5 adhesive precipitated hydroxyapatite and calcium carbonate (SEM/EDX, ATR/FTIR, and XDR). The addition of 45S5 and NbG to the adhesives improved the stability of the resin-dentin interface after 1 year. Significance. The incorporation of microparticles from 45S5 bioactive glass in self-etching adhesive systems is considered an excellent alternative for the development of a bioactive adhesive that improves the integrity of the hybrid layer on sound dentin. (c) 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

关键词： Bacteriocins   Recombinant proteins   Enterocin A   pyocin R   Lactocin   Anticancer  

摘要： Gastric cancer treatment remains a major challenge. There are many reports on the positive efficacy of Bacteriocins associated with anti-cancer sequences. The main purpose of this study was to determine and design a fusion gene contraceptive containing anticancer Enterocin A, R-type pyocin, Lactocin, ligand against AGS gastric cancer cell line using Real Time_ RT_ PCR technique. This study was designed EntA-PynR-Lac recombinant proteins containing ligand and anticancer using bioinformatics software. Escherichia coli BL-21 was used to express cloned genes in expression vectors that have a T7 bacteriophage promoter. The specific ligand of the AGS cell line was designed and added to the recombinant construct sequence, and its three-dimensional structures, conformity, and stability were evaluated. Synthesis of fusion gene concentrate was performed in the expression vector, the transformation of the recombinant plasmid containing anticancer fusion gene construct in the respective host. Confirmation and purification of the recombinant protein by Western blotting and nickel column chromatography through the His tag, cytotoxicity determination against AGS cell line via the MTT technique, and finally, Real-time PCR was performed. Protein fusion at a concentration of 80 mu g/ml in 24 h kills 83% of the cells tested and treatment of the cells with this concentration leads to increased expression of caspase3 and bax genes and decreased expression of bcl2. The results show that the treatment of gastric cancer cells with recombinant protein at a concentration of 80 mu g/ml induces apoptosis in this cell line.