Synthesis and spectroscopic studies of some new azobenzenesulfonamide

Abstract

Diazotized sulfadiazine derivative (1) was coupled with some nitrogen heterocyclic namely (thiazolone derivatives 2a–c, thiazole derivatives 4a–c and barbituric acid derivatives 6a,b) to give the corresponding azo compounds 3a–c, 5a–c and 7a,b in good yields. The newly synthesized azo benzene sulfonamide dyes were recorded their UV visible spectra in the region 200–600?nm in four different solvents and discussed the effect of solvents, substituent and effect of acid and base on the absorption values of these dyes.     

适用于“一步酸溶法”生产氧化铝工艺中稀释料浆的高分子絮凝剂的合成

为达到"一步酸溶法"生产氧化铝工艺中稀释料浆在高温、高酸度工况下进行固液高效分离的目的,以丙烯酰胺(AM)与阳离子(DMDAAC)为共聚单体,通过水溶液聚合法合成了阳离子聚丙烯酰胺(CPAM)絮凝剂。以转化率和相对分子质量为目标,通过单因素分析法确定了最优的合成工艺条件,即反应温度30℃,单体总质量分数为30%,阳离子度5%,K2S2O8和NaHSO3质量分数均为0.005%,2,2′-偶氮二(2-脒基丙烷盐酸盐)(V50)质量分数为0.0025%,乙二胺四乙酸(EDTA)质量分数为0.05%的条件下,反应时间为6 h,获得相对分子质量为1.2×107溶解性能较好的阳离子型聚丙烯酰胺(CPAM)。     

Peracetic acid as a single endodontic irrigant: effects on microhardness,roughness and erosion of root canal dentin

The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl.     

FDM 3D打印工艺参数对PLA制件力学性能的影响

采用五因素四水平正交试验设计,对16组不同工艺参数(打印层厚、填充密度、打印温度、填充速度、外壳厚度)的FDM 3D打印聚乳酸(PLA)制件力学性能进行了测试和结果分析,确定了影响PLA制件力学性能的主要因素,其中,外壳厚度对制件力学性能影响最为明显,打印温度影响最小,同时分析得到了在打印层厚0.15 mm,填充密度40%,打印温度210℃,填充速度60 mm/s,外壳厚度1.6 mm条件下可获得力学性能最佳的制件。最后对试验数据进行回归分析,拟合得到了FDM打印工艺参数与PLA制件力学性能指标的数学模型;通过对不同打印工艺参数的试样进行试验验证,表明该模型拟合误差小(5%以内),可靠性高,可用来对FDM 3D打印制件的加工提供参考。     

Effect of storage time and temperature on hydrogen fermentation of food waste

Practically, before being fed to the treatment plant, food waste (FW) is stored for up to a week in a storage tank under ambient temperature condition, which would have an impact on the bioenergy yield. In the present work, FW was stored at different temperatures (5 °C, 20 °C, and 35 °C) for 0 d, 1 d, and 2 d, and it was used as a feedstock for mesophilic H₂ fermentation. H₂ production curves were divided by three groups, finally attaining 1.7–1.8 mol H₂/mol hexose_added, 1.4–1.5 mol H₂/mol hexose_added, and 1.2 mol H₂/mol hexose_added, achieved from the (fresh, FW stored at 5 °C), (FW stored at 20 °C, and 35 °C for 1 d), and (FW stored at 35 °C for 2 d), respectively. The different performance was attributed to the growth of indigenous lactic acid bacteria such as Lactobacillus and Weissella during storage under high temperature condition. In addition, it was found that the activity of homoacetogenic reaction (R17, 4H₂ + CO₂ → Acetate) calculated by establishing metabolic flux balance was different depending on the H₂ production performance. The flux of R17 ranged 0.03–0.06 under low H₂ yield achieved conditions, while it increased to 0.10–0.17 those showing low H₂ yields.     

Physicochemical Properties,Lipid Oxidation,and Fatty Acid Composition of Sausage Prepared with Meat of Young Nellore Bulls Fed a Diet with Lauric Acid

This study evaluates the quality of sausage obtained from the meat of Nellore cattle fed diets containing different levels (0, 5, 10, and 15 g per kg total DM) of lauric acid (C12:0) from palm kernel cake. A linear reduction (p ≤ 0.05) in lipid oxidation, as reflected by linear decreases in the lightness (L*), yellowness (b*), and saturation (C*) color parameters, is observed on days 7, 14, and 21 of maturation of sausage, and these decreases are accompanied by linear increases in the redness (a*) color and the linoleic (C18:2n–6) and linolenic (C18:3n–3) fatty acid contents. The inclusion of lauric acid in the diet induces linear reductions in the shear force and cooking loss and does not significantly affect various indices, including the centesimal composition, water activity, water holding capacity, composition of most fatty acids (FA), hypocholesterolemic‐to‐hypercholesterolemic FA ratio, atherogenicity, thrombogenicity, and desirable fatty acids. The use of dietary lauric acid from palm kernel cake is recommended at doses up to 15 g per kg because its presence reduces lipid oxidation and improves color parameters, softness, and linoleic and linolenic FA without affecting the FA composition of sausage from Nellore bull's meat. Practical applications : Sausages are products manufactured from chopped or ground meats packaged into animal casings. This product appeared in Brazil through the adaptation of traditional recipes brought by German and Italian immigrant families to weather conditions and the national palate. However, due to its production characteristics, sausage can become a product with lipid characteristics that are undesirable for human consumption. The inclusion of lauric acid (C12:0) in the animal diet might change the biohydrogenation process in the rumen, improve the quality of the deposited FA and reduce lipid oxidation in sausage manufactured from meat. The FA composition and physicochemical properties of sausage predict its acceptance by the consumer market. An optimal advantage would be achieved if these products can be used as not only preservatives but also functional ingredients with antioxidant properties and products for the treatment of metabolic syndrome and cardiovascular diseases through atherogenic action.     

破囊壶菌发酵生产DHA的研究进展

二十二碳六烯酸（DHA）是一种非常重要的多不饱和脂肪酸，能参与人及动物体内多个生理过程。破囊壶菌具有生长迅速、细胞内DHA含量高的特点，是工业化生产DHA的潜力菌。本文主要介绍破囊壶菌DHA代谢通路、影响破囊壶菌生产DHA的因素以及破囊壶菌中试发酵的研究现状。首先，对破囊壶菌合成DHA的两个代谢途径，即脂肪酸合成酶（fatty acid synthesis pathway，FAS）途径和聚酮合酶（polyketide synthesis pathway，PKS）途径进行总结和描述；其次，对影响破囊壶菌发酵生产DHA的三个主要因素（碳氮源、溶氧和温度）进行综述；随后，阐述了破囊壶菌发酵生产DHA的中试放大工艺的研究现状；最后，提出破囊壶菌发酵生产DHA过程中存在的问题，并指出进一步分离获得优质的破囊壶菌菌株、对其代谢途径和关键酶的研究以及中试放大工艺的研究是下一步研究的重点。通过对上述一系列问题进行综述，旨在为利用破囊壶菌工业化生产DHA提供一定的参考。