Biogenic amines in Spanish beers: differences among breweries

Ten biogenic amines in Spanish beers were studied using HPLC. Agmatine, tyramine and putrescine were the prevailing amines, while histamine,-phenylethylamine, tryptamine, cadaverine, spermine and spermidine were detected at relatively low levels (in general <2 mg/l). On the basis of the wide range of levels observed for tyramine (from 1.90 to 31.55 mg/l), the consumption of beer requires restriction in patients receiving monoamine oxidase inhibitor drugs. Biogenic amine levels in beers of the same type from the same company and from different companies were monitored every month over 1 year. Agmatine and putrescine levels showed minimal fluctuations in beers from the same company as well as from different breweries. Raw materials and brewing conditions would not affect the levels of those amines. However, tyramine levels were subject to wide fluctuations in beers produced by particular breweries irrespective of whether they were produced by the same company. Relatively high levels of tyramine were specific to some breweries.     

QSAR结合人工神经网络方法研究取代芳烃分子结构与Na-K-ATP酶活性

运用函数连接型神经网络研究 3 8种取代芳烃化合物的分子结构—毒性的定量构效关系 (QSAR) ,计算结果与MLR计算结果比较 ,前者比后者好。与实验结果的线性拟合相关系数 ,FLN所得结果为 0 9561～ 0 9996,MLR所得结果为 0 869～ 0 965。     

The molecular structure of asphaltene: an unfolding story

From detailed chemical and thermal degradation studies, a host of structural units have been identified in Alberta asphaltenes. It has been shown that the extent of aromatic condensation is low and that highly condensed pericyclic aromatic structures are present in very low concentrations. From the available data reported to date, it is concluded that petroleum asphaltenes were mainly derived through the catalytic cyclization, aromatization and condensation of n-alkanoic, probably fatty acids, precursors.     

EPISODIC SUSPENDED SEDIMENT TRANSPORT AND ELEVATED POLYCYCLIC AROMATIC HYDROCARBON CONCENTRATIONS IN A SMALL,MOUNTAINOUS RIVER IN COASTAL CALIFORNIA

Suspended sediment and organic contaminants were measured during a period of 2 years in the San Lorenzo River, central California, which discharges into the Pacific Ocean within the Monterey Bay National Marine Sanctuary, in an effort to quantify the potential environmental effects of storm events from a steep, mountainous coastal urban watershed. Most suspended sediment transport occurred during flooding caused by winter storms; 56% of the total sediment load for the 2‐year study was transported by the river during one storm event in January 2010. Concentrations of polycyclic aromatic hydrocarbons can exceed regulatory criteria during high‐flow events in the San Lorenzo River, and total annual polycyclic aromatic hydrocarbon load was on the order of 10 kg in water year 2010. These results highlight the importance of episodic sediment and contaminant transport in steep, mountainous coastal watersheds and emphasize the importance of understanding physical processes and quantifying chemical constituents in discharge from coastal watersheds on event‐scale terms. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

黄河河口段水-沙-芳烃类污染物相互作用的数值研究

考虑复合污染条件下泥沙吸附污染物和泥沙冲淤运动对污染物输移扩散特性的影响,建立了非恒定非饱和输沙模型和污染物迁移转化模型,并结合黄河河口段利津至清7河段监测数据,研究该河段水流、泥沙过程及污染物迁移转化规律,分析了多组份共存的复合污染条件下苯酚、苯胺及氯苯之间的吸附竞争关系及其浓度变化情况。研究结果表明,从上游到下游先冲刷后淤积的河段中,溶解态污染物浓度值沿程降低,吸附态污染物浓度值沿程升高。三组分复合体系下各污染物之间存在竞争吸附,吸附态苯胺浓度值升高而溶解态浓度值降低,苯酚和氯苯在泥沙上的吸附作用受到抑制,吸附态浓度值有所下降,溶解态浓度值略有升高。     

MEA-AMP混合醇胺捕集烟气二氧化碳过程分析

本文根据焦化烟道气实际数据,应用流程模拟软件Aspen Plus模拟分析了MEA吸收剂以及MEA和空间位阻胺AMP混合吸收剂捕集烟道气中CO₂的吸收解吸效果。结果表明,混合胺浓度30 wt%（摩尔比MEA:AMP=1:1）吸收剂的吸收效果较好,为了进一步考察该种配比混合胺吸收剂的吸收、解吸特性,对其进行了灵敏度分析,并选取了25 wt%MEA为基准吸收剂,对比分析了进料温度、解吸塔再沸器热负荷和解吸塔压力对吸收解吸效果的影响,当吸收剂进料温度40℃时,单一MEA吸收剂吸收CO₂效率86.8%,混合胺的吸收率89.6%:2种吸收剂达到55%的解吸率,单一MEA吸收剂工艺再沸器热负荷为4500 kW,混合胺吸收剂工艺再沸器热负荷为3000 kW;当解吸塔压力1.5 bar时,单一MEA吸收剂对CO₂解吸率52.4%,混合胺吸收剂的解吸率55.8%,由对比结果得出混合胺（摩尔比MEA:AMP=1:1）的吸收、解吸效果均优于单一25 wt%MEA吸收剂。     

硫酸铈氧化对二甲苯制对甲基苯甲醛

用硫酸铈为媒质间接电氧化对二甲苯制对甲基苯甲醛。在优选的条件下，电氧化Ｃｅ（ＩＶ）的产率≥８５％。采用十二烷基硫酸钠等催化剂可以明显地加速合成对甲基苯甲醛的反应。     

胺法在脱碳工艺中的应用

主要介绍了MDEA及空间位阻胺这两种高效，低耗的脱碳合成氨原料气和天然气脱碳工艺中的应用情况。     

芳烃化合物对普通小球藻毒性的QSAR研究

用DFT-B3LYP方法,在较高基组6-311G**水平下,全优化计算了23种苯胺、苯酚和苯甲醛衍生物。从中获得前线分子轨道能级(EHOMO,ELUMO),最正氢原子电荷Q ,最负非氢原子电荷Q-,及分子偶极矩和体积(μ,V)等描述符。结合文献中标题化合物对普通小球藻的毒性值(-logEC50)和疏水性参数(logKow),由线性回归方法成功建立QSAR模型。将-logEC50与logKow直接相关,发现标题物对普通小球藻的毒性均高于基本毒性,而多元线性回归所得二变量模型(-logEC50=-1.945 0.612logKow-7.690ELUMO,n=23,R2=0.834,F=50.322,SE=0.274,P=0.000,VIF=1.093)能更好地描述标题物对普通小球藻的毒性,由此推断,标题物取非共价作用毒性机理,其对普通小球藻的毒性作用分为两步,首先穿过细胞壁在细胞内富集,以logKow描述;其次与亲核试剂发生亲电反应,以ELUMO表示。     

双马来酰亚胺改性芳香胺固化剂的合成与表征

以二苯甲烷双马来酰亚胺(BMDPM)和芳香二胺为原料,经溶液反应合成了BMDPM改性二胺WDDM521,并以单官能环氧化合物丁基缩水甘油醚(GLY)对WDDM521二胺进行了化学增韧改性,得到GHJ1固化剂。改性二胺WD-DM521和GHJ1均适宜用作环氧树脂固化剂。研究了WDDM521溶液的反应温度,并采用红外光谱(FTIR)、凝胶渗透色谱(GPC)及核磁共振(NMR)等手段表征了上述2种固化剂的结构。