排序方式: 共有33条查询结果,搜索用时 31 毫秒
1.
Anastasia C. Boussia Stamatina N. Vouyiouka Athanasios D. Porfiris Constantine D. Papaspyrides 《大分子材料与工程》2010,295(9):812-821
Long‐aliphatic‐segment polyamides were prepared based on hexamethylenediamine and α,ω‐(CH2)x biosynthetic diacids (x = 10, 11, 12). The pertinent monomers (salts) were isolated as solids, thoroughly characterized for the first time, and then submitted to an anhydrous melt prepolymerization technique. The obtained prepolymers exhibited in the range of 5 100–11 800 g · mol?1, and the molecular weight was further increased by up to 55% through solid‐state finishing. The suggested overall polyamidation cycle was conducted at short melt‐reaction times, so as to avoid any thermal degradation, and was proved efficient, indicating similar reactants polymerizability independently of the methylene content.
2.
Stamatina Kallithraka Laura Aliaj Dimitris P. Makris Panagiotis Kefalas 《International Journal of Food Science & Technology》2009,44(12):2385-2393
A range of fourty‐six red grape (Vitis vinifera spp.) samples, originating from six widely cultivated varieties and covering major parts of the Hellenic vineyard, were assayed for their content in six principal anthocyanin pigments. Representative in vitro antioxidant parameters were also determined, including antiradical activity (AAR), reducing power (PR) and hydroxyl free radical scavenging activity (SAHFR). Quantitative determination using high performance liquid chromatography showed that the prevalent pigment was malvidin 3‐O‐glucoside (average content 82.53 mg per 100 g fresh berry weight), followed by its coumarate derivative (29.26 mg per 100 g), paeonidin 3‐O‐glucoside (10.84 mg per 100 g), petunidin 3‐O‐glucoside (7.80 mg per 100 g) cyanidin 3‐O‐glucoside (5.67 mg per 100 g) and delphinidin 3‐O‐glucoside (1.28 mg per 100 g). The richest variety was Syrah, with total average anthocyanin content of 186.02 mg per 100 g, whereas the Hellenic native variety Xinomavro had the lowest average anthocyanin level (38.70 mg per 100 g). The establishment of correlations of individual and total anthocyanin contents with the values from the antioxidant test was accomplished with linear regression. The links of total anthocyanins were significant with all antioxidant parameters (P < 0.001), but more importantly with SAHFR (R2 = 0.740). Malvidin 3‐O‐glucoside content had the higher correlation with SAHFR compared with all other anthocyanins (R2 = 0.698, P < 0.001). 相似文献
3.
Eleni Psarra Dimitris P Makris Stamatina Kallithraka Panagiotis Kefalas 《Journal of the science of food and agriculture》2002,82(9):1014-1020
The total hydroxycinnamate (THC) and total flavanol (TF) contents were determined in 26 selected Greek white wines of ‘Appellation of Origin of High Quality’ using well‐established spectrophotometric methodology. Furthermore, two parameters related to the antioxidant capacity of wines, the antiradical activity (AAR) and the reducing power (PR), were also determined using the stable DPPH· radical and a ferric reducing power assay respectively. THC content varied from 64.4 to 197.1 mg l?1 chlorogenic acid equivalents (CGAE), whereas TF content exhibited larger variation, ranging from 3.3 to 205.3 mg l?1 catechin equivalents (CTE). AAR and PR were found to range from 0.47 to 0.60 mM Trolox equivalents (TRE) and from 0.32 to 2.05 mM quercetin equivalents (QE) respectively. Regression analysis at 95% significance level indicated that reducing effects are likely to be exerted by the flavanol fraction (SF < 0.05), as opposed to antiradical efficiency which is primarily affected by the sum of THC and TF contents (SF < 0.05), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. © 2002 Society of Chemical Industry 相似文献
4.
5.
The traditional PA 6.6 production route, i.e. solution melt polymerization followed by extrusion, is applied to the in situ intercalation of PA 6.6/clay nanocomposites. Organoclays of different types are tested and the derived nanocomposites are thoroughly characterized in terms of molecular weight, thermal properties and morphology. Reaction acceleration is found in the presence of fully exchanged organoclays, which is attributed to a chain extension mechanism based on clay SiOH groups. Analysis of the nanocomposites' nanostructure indicates that the applied solution melt polymerization process results in some flocculation of the tested organoclays, which is improved in some cases after extrusion and leads to partially exfoliated nanocomposites.
6.
Stamatina N. Vouyiouka Viviane Filgueiras Constantine D. Papaspyrides Enrique L. Lima Jose Carlos Pinto 《应用聚合物科学杂志》2012,124(6):4457-4465
Poly(ethylene terephthalate‐co‐isophthalate) (PETI) prepolymer was submitted to solid state polymerization (SSP) at 184–230°C in a fixed bed reactor, to study the evolution of morphological changes during the process. Short reaction times were selected to investigate crystallization phenomena during nonisothermal (heating) and isothermal SSP phases. More specifically, multiple PETI melting behavior was observed and attributed to secondary crystallization, the rate of which increased significantly with SSP temperature. Reaction time was also found to exert a positive effect on solid‐phase perfection of secondary crystals, leading at each temperature to melting points close to the value of bottle‐grade poly(ethylene terephthalate). Finally, the mass fraction crystallinity of the SSP grades was found to comply with the crystal morphology encountered. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
7.
Chryssanthi Pateraki Spiros Paramithiotis Agapi I. Doulgeraki Stamatina Kallithraka Yorgos Kotseridis Eleftherios H. Drosinos 《European Food Research and Technology》2014,239(6):1067-1075
The aim of the present study was to assess the effect of sulfur dioxide addition in the wild yeast population dynamics as well as the polyphenolic composition during spontaneous red wine fermentation from Vitis vinifera cultivar Agiorgitiko. The grapes were crushed and fermentation took place at 21 °C without the addition of any commercial yeast, and with and without the addition of 40 mg L?1 SO2. A combination of culture-dependent and culture-independent techniques was used for wild yeast population dynamics assessment and HPLC analysis for the determination of polyphenolic compounds. Regarding the former, the effect of sulfur dioxide addition was only marginal since Saccharomyces cerevisiae strains dominated the fermentation from the first day; strains belonging to Hanseniaspora spp., Lachancea thermotolerans and Metschnikowia pulcherrima species appeared only occasionally. As far as the polyphenolic content was concerned, it was enhanced with sulfur dioxide addition; however, as time progressed, the differences were reduced, suggesting that the time the juice was in contact with the skins was of greater importance than sulfur dioxide addition. 相似文献
8.
Nikos Sioumis Stamatina Kallithraka Epaminondas Tsoutsouras Dimitris P. Makris Panagiotis Kefalas 《European Food Research and Technology》2005,220(3-4):326-330
Browning is a serious problem in relation to white wine quality and mostly affects the sensory attributes, whereas its impact on the dietary value of wines has never been investigated. Browning, however, is well known to be associated with polyphenol oxidation, and therefore it may be accompanied by changes in the antioxidant capacity. On the basis of this consideration, experimental white wines vinified and stored under identical conditions were subjected to accelerated browning, and efforts were made to distinguish compositional parameters that might be related to the extent of browning development. Further, the consequences of browning on the reducing power and antiradical activity were assessed. It was shown that none of the parameters examined (titratable acidity, pH, total SO2, total polyphenols and total flavanols) play an important role in browning onset, but SO2 appeared to exert a statistically significant influence (r2=0.6394, P<0.05) on the percentage change in the antiradical activity. Evidence also suggested that browning development might be prominently associated with decreases in both antiradical activity (r2=0.7891, P<0.01) and reducing power (r2=0.6925, P<0.05). 相似文献
9.
Production of biodegradable polyesters via enzymatic polymerization and solid state finishing 下载免费PDF全文
Maria Kanelli Aliki Douka Stamatina Vouyiouka Constantine D. Papaspyrides Evangelos Topakas Lefki‐Maria Papaspyridi Paul Christakopoulos 《应用聚合物科学杂志》2014,131(19)
The synthesis of aliphatic polyesters (PEs) derived from diols (1,4‐butanediol and 1,8‐octanediol) and diacids or their derivatives (diethyl succinate, sebacic acid, 1,12‐dodecanedioic acid, and 1,14‐tetradecanedioic acid) was achieved in order to produce poly(butylene succinate) (PE 4.4), poly(octylene sebacate) (PE 8.10), poly(octylene dodecanate) (PE 8.12), and poly(octylene tetradecanate) (PE 8.14). The herein suggested procedure involved two stages, both sustainable and in accordance with the principles of “green” polymerization. The first comprised an enzymatic prepolymerization under vacuum, in the presence of diphenylether as solvent using Candida antarctica lipase B as biocatalyst, whereas a low‐temperature postpolymerization step [solid state polymerization (SSP)] followed in order to upgrade the PEs quality. In the enzymatically synthesized prepolymers, the range of number–average molecular weight attained was from 3700 to 8000 g/mol with yields reaching even 97%. Subsequently, SSP of PE 4.4 and 8.12 took place under vacuum or flowing nitrogen and lasted 10–48 h, at temperatures close to the prepolymer melting point (Tm ? TSSP varied between 4°C and 14°C). The solid state finishing led to increase in the molecular weight depending on the prepolymer type, and it also contributed to improvement of the physical characteristics and the thermal properties of the enzymatically synthesized PEs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40820. 相似文献
10.
Triga K Dousdampanis P Aggelakou-Vaitis S Gellner K 《Hemodialysis international. International Symposium on Home Hemodialysis》2012,16(1):109-112
New-onset psoriasis is extremely rare in hemodialysis (HD) patients, and several trials of dialysis therapies (HD and peritoneal dialysis) in psoriasis have indicated remarkable improvement in skin lesions and well-being even in patients without renal impairment. We describe a patient who developed severe psoriasis despite undergoing chronic maintenance hemodialysis for 5 years and was treated successfully with oral cyclosporin A. 相似文献