高效液相色谱法测定水中痕量丙烯酰胺

建立旋转蒸发浓缩固相萃取与高效液相联用测定水中痕量丙烯酰胺的方法。水样经旋转蒸发浓缩活性炭固相萃取柱净化后进行高效液相色谱分析,流动相为甲醇：水（10∶90）,流速为0.8 mL/min,进样量为20μL,检测波长为210 nm,丙烯酰胺标准溶液介质为超纯水。试验表明：在同等条件下采用超纯水配制标准丙烯酰胺溶液进行高效液相测定的灵敏度比用甲醇配制的高5倍,线性范围为5～250μg/Lr,=0.999 8;在浓缩100倍的条件,丙烯酰胺回收率为83%￣95%,水样最低检测限为50 ng/L。该方法经济、简单、灵敏、准确,可向常规实验室推广。     

The effect of parboiled rice on glycemia in Wistar rats

Starch is an important energy source and can represent more than 60% of the calories of the human diet. The starch fraction resistant to enzymatic digestion is called resistant starch. When rice is parboiled, the starch retrogrades with the formation of type 3-resistant starch (retrograded), which presents beneficial effects on the health, since it acts as a prebiotic. In the present study three types of rice were selected, with high, medium and low amylose contents, with the objective of evaluating the effects of conventional and parboiled rice on glycemia in Wistar rats. The samples with high and medium amylose contents were soaked for 6 h at 65 degrees C, and the low amylose sample for 7 h at 70 degrees C. The samples were subsequently autoclaved for 10 minutes at 0.7kgf x cm(-2). Six male Wistar rats were used for each treatment. Seven experimental diets were elaborated, formulated according to AIN-93M, the control diet and diets substituting the carbohydrate source with conventional or parboiled rice. Resistant starch was determined in the diets and glycemia monitored using glucose paper strips, the sample being blood obtained from the distal part of the rat's tail. For the glycemic curve, glycemia was measured in the fasting state and during 90 minutes post-prandial. The results indicated there were no significant differences between the diets formulated with high, medium and low amylose, parboiled or conventionally prepared, with respect to fasting or post-prandial glycemia in Wistar rats.     

Effects of cis-9,trans-11 CLA in rats at intake levels reported for breast-fed infants

CLA intake in exclusively breast-fed infants is close to levels found to have physiological effects in animals. However, in the majority of studies mixtures of CLA isomers have been used and the independent effects of the major CLA isomer in human milk, cis-9, trans-11 CLA, at the intake level in exclusively breast-fed infants have hardly been studied. We therefore studied the effects of cis-9, trans-11 CLA on plasma lipids and glucose, immune function, and bone metabolism in growing rats. Thirty male Sprague-Dawley rats (n=10/group) were fed either 20 mg/kg/d cis-9, trans-11 CLA and 20 mg/kg/d sunflower oil (CLA20), 40 mg/kg/d cis-9, trans-11 CLA (CLA40), or 40 mg/kg/d sunflower oil (placebo) for 8 wk. No significant differences between groups were found in plasma lipids, glucose, insulin, C-reactive protein, or lipid peroxidation. Liver fat content was lowest in the CLA20 group. In vitro interleukin 2 (IL-2) production increased, and tumor necrosis factor alpha, IL-1β, prostaglandin E₂, and leukotriene B₄ production decreased in the CLA20 group. No differences between groups were detected in IL-4, IL-6, or interferon gamma production, plasma osteocalcin, insulin-like growth factor, or urinary deoxypyridino line crosslinks. Plasma tartrate-resistant acid phosphatase 5b activity was significantly increased in the CLA40 group. The results indicate anti-inflammatory effects and enhanced T-cell function for the CLA20 group. No adverse effects were seen in the CLA20 group, whereas indications of increased bone resorption rate were observed in the CLA40 group.     

Mild ingestion of used frying oil damages hepatic and renal cells in Wistar rats

Male Wistar rats were fed ad libitum a powdered diet (AIN93G; no fat) containing 7 wt% of fresh oil (control) or used frying oil recovered from Japanese food manufacturing companies (recovered oil) for 12 weeks and subjected to anthropometric measurements, hematological analyses, and observations of the liver and kidneys. All of the rats grew well, and no gross symptoms attributable to recovered oil were observed. There was a tendency toward higher consumption of the diet in the experimental group as compared to the control group. In the serum of the experimental group, no difference was detected in the levels of glucose, triacylglycerol, and phospholipids. But many dark-red patches, necrosis, and bleeding were found in the livers of 75% of the experimental rats; these rats had extremely high aspartate aminotransferase (AST) and alanine aminotransferase (ALT) values. Average AST and ALT values of the experimental group were significantly higher than those of the controls. The renal cells were also obviously damaged. These results raise the concern that frying oil contained in ready-made foods, snacks, etc., if deteriorated to an extent equal to or greater than that of the recovered oil, may be able to change human serum AST/ALT levels and damage the liver and kidneys.     

Effects of flour sources on acrylamide formation and oil uptake in fried batters

Food batters were formulated using flours of long-grain rice, waxy rice, wheat, or corn. Acrylamide and oil analyses were conducted for the flour and the corresponding fried batter. During frying, the formation of acrylamide ranged from 82 ng/g for the long-grain rice batter to 263 ng/g for the corn batter. Oil uptake ranged from 21.4% for the long-grain rice batter to 47.3% for the wheat batter. The incorporation of 5% pregelatinized rice flour and 1.5–3.0% milk as functional additives into the long-grain rice batter only slightly increased the acrylamide and oil contents.     

Transformation of bile acids and sterols by clostridia (fusiform bacteria) in Wistar rats

The effects on bile acid and sterol transformation of clostridia (fusiform bacteria), the dominant intestinal bacteria in rodents (ca. 10¹⁰ counts per g wet feces) were examined in Wistar rats. After inoculation of clostridia into germ-free rats and into rats previously inoculated solely with Escherichia coli, most of the endogenous bile acids were deconjugated, and cholic acid and chenodeoxycholic acid were 7α-dehydroxylated to deoxycholic acid and lithocholic acid, respectively. Tauro-β-muricholic acid, another major bile acid in rats, was deconjugated, but only part of it (ca. 30%) was transformed into hyodeoxycholic acid. Cholesterol and sitosterol were also reduced to coprostanol and sitostanol, respectively. Escherichia coli transformed neither bile acids nor sterols. These data suggest that clostridia play an imporant role in the formation of secondary bile acids and coprostanol in rats.     

Effects of trace elements on transition metal cohesion

First-principles atomic cluster calculations of the effects of trace elements on transition metal cohesion have identified different mechanisms of cohesive enhancement and decohesion. This study of Li-row interstitial atoms in a Ni₆ octahedral host shows that elements which form covalent bonds with host atoms without leading to much strain (e.g. B and C) increase the cohesive strength of the host. Decohesion, a lowering of the cohesive strength of the host, is promoted by trace elements which favor the formation of ionic bonds (e.g. Li and F). In this case, decohesion occurs by mechanisms involving metal-metal bond density reduction (by charge transfer and/or Pauli exclusion) and/or by incomplete screening of the impurity nucleus. These mechanisms are identified through directly calculated restoring forces in the cluster and analysis of deformation densities which detail the charge density rearrangements in the host in the presence of Li-row interstitial atoms.     

Effects of agitation in emulsion polymerization of vinyl acetate,ethylene, and N-methylol acrylamide

The emulsion polymerization of vinyl acetate monomer (VAM), ethylene and N-methylol acrylamide (NMA) was carried out in a high pressure stirred reactor using an Rushton flat blade impeller at a rotational speed of 300 rpm under a semi-batch polymerization process, which was subsequently grown by the continuous addition of monomers (VAM, ethylene, and NMA). The particle diameters of the samples withdrawn during polymerization were determined by using capillary hydrodynamic fractionation (CHDF). Also, the number of particles was calculated from the data obtained by CHDF. Coagulum formation was studied. It was found that coagulum formation increased with increasing conversion and auto-accelerated from ca. 20% conversion. The definition of coagulum in this research was presented. The coagulum formation pattern on the impeller was shown. Also, the flow pattern in the reactor under the same geometrical configuration and operating conditions was simulated.     

Swelling behavior of poly(acrylamide)/clay nanocomposite hydrogels in acrylamide aqueous solution

The swelling behaviors of poly(acrylamide) (PAAm)/clay nanocomposite hydrogels (hereinafter abbreviated as NC gels) in acrylamide (AAm) aqueous solution have been investigated. As‐prepared PAAm/clay hydrogels (S‐M gels) were posttreated by immersing them in AAm aqueous solution. It was found that the swelling ratio of the NC gels increased greatly when the concentration of the solution is below a critical concentration (c*), whereas the gels were disintegrated in the solution when the concentration of the solution is above the c*. Some disc‐like particles were found in the AAm solution accompanying with the unusual swelling behaviors. This unusual swelling behavior is resulted from the change of network structure of the NC gels in AAm aqueous solution, which was further convinced by transmission electron microscopy and element analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Zanthoxylum piperitum, an Asian spice, inhibits food intake in rats

We investigated the effects of a total extract from Zanthoxylum piperitum fruit, of the volatile components of extract, and of a non-volatile fraction containing the major alkylamides of Zanthoxylum (NVA) on food intake in rats. In Experiment 1, three groups (A, B, C) of mildly food deprived rats were given one hour long feeding trials during which they were offered choices between an oat-bran wafer paired with vegetable oil and a wafer paired with a Zanthoxylum preparation in vegetable oil. Trials were divided into three blocks of two tests each. During Blocks 1 and 3, two wafers coated with vegetable oil were offered to establish baseline consumption. During Block 2, Group A was given choices between wafers coated with oil and wafers coated with total extract. Group B was offered oil coated wafers and wafers coated with the NVA fraction. Group C received two oil coated wafers. One was served on top of a screened dish containing a sample of total extract. In this manner, the rats were exposed to volatile compounds emanating from the extract but could not contact the extract. The second wafer was served on top of a screened sample of oil. Results: In Blocks 1 and 3 trials, the rats fed indiscriminately from both wafers. During Block 2, total extract, the NVA fraction and the volatile compounds from extract all significantly reduced food consumption. In Experiment 2, habituation to the NVA fraction and to the volatile constituents of extract was examined in two additional groups (D, E), using the methods described above. Baseline consumption was tested in Blocks 1 and 3 by offering two oil coated wafers. During Block 2, group D was given 10 trials with oil coated and NVA-fraction coated wafers. Group E was given 10 trials with oil coated wafers paired with the volatile constituents of total extract and with those of oil. Results: Both groups failed to habituate to the Zanthoxylum stimuli. Wafers treated with the NVA fraction and wafers paired with the volatile constituents of extract were avoided throughout the 10 test days.     

丙烯酰胺聚合物与发泡剂对油水界面性质及乳状液稳定性的影响

用界面张力仪、表面黏弹性仪和Zeta电位仪研究了胜利埕东油田聚合物强化泡沫复合驱中聚合物和/或发泡剂质量浓度对油水界面特性及乳状液稳定性的影响.结果表明,随聚合物质量浓度增加,模拟水与原油模拟油间油水界面张力、界面剪切黏度和油滴表面的Zeta电位绝对值增大;而随发泡剂质量浓度增加,模拟水与原油模拟油间的界面张力降低,界面剪切黏度有所增加,但变化幅度很小,油滴表面的Zeta电位绝对值增大;原油模拟油与含聚合物和发泡剂的模拟水间所形成的W/O乳状液稳定性随聚合物和/或发泡剂质量浓度增加而增强.     

Adiabatic photopolymerization of acrylamide

Although the adiabatic polymerization of acrylamide using photoinitiation was first described over 30 years ago, it still offers convenient opportunities for innovation. In the present work, the effect of EDTA (ethylenediaminetetraacetic acid, tetrasodium salt) as a reducing agent with two photosensitizers is described. With riboflavin-5'-phosphate sodium, the rate of polymerization rises with the ? power of the EDTA concentration. With a new photosensitizer, 4-benzoyl-N,N,N-trimethylbenzenemethanaminium chloride, the rate rises with the ½ power of the EDTA concentration. Adiabatic temperature rise is used as the measure of conversion in the early stages of polymerization.     

双丙酮丙烯酰胺的合成

以丙酮和丙烯腈为原料,浓硫酸为催化剂,合成双丙酮丙烯酰胺(DAAM),确定较优条件为反应时间5h,反应温度55℃,n(丙酮)∶n(丙烯腈)∶n(浓硫酸)=2.4∶1∶2.4,阻聚剂的用量为丙酮质量的0.5%。对分离精制过程中的碱液洗涤过程进行了优化,确定较佳条件为碱液质量分数20%,碱液用量30mL,碱洗时间60min。在上述条件下反应得到的产品的收率约为65%,产品质量分数达99.3%,熔点54~56℃。采用FT-IR与1 HNMR对产物结构进行了表征。     

Synthetic hydrogels. 1. Effects of solvent on poly(acrylamide) networks

Acrylamide hydrogels were synthesized in a series of hydro-organic solvents to examine how solvent affects the network structure by influencing properties of the first formed polymer in the reaction mixture. The looser and more heterogeneous network structure of gels formed in aqueous solutions of ethylene glycol or propylene glycol was found to be largely due to the reduced chain lengths of the primary polymer molecules. Results from NMR analysis of the monomer, and intrinsic viscosity measurements of the polymer in various solvents indicate that solvent effects on the reactivity of the monomer and the propagating radical impose an overriding control over properties of the resultant networks.     

Effects of Virgin Olive Oil on Blood Pressure and Renal Aminopeptidase Activities in Male Wistar Rats

High saturated fat diets have been associated with the development of obesity and hypertension, along with other pathologies related to the metabolic syndrome. In contrast, the Mediterranean diet, characterized by its high content of monounsaturated fatty acids, has been proposed as a dietary factor capable of positively regulating cardiovascular function. These effects have been linked to changes in the local renal renin angiotensin system (RAS) and the activity of the sympathetic nervous system. The main goal of this study was to analyze the role of two dietary fat sources on aminopeptidases activities involved in local kidney RAS. Male Wistar rats (six months old) were fed during 24 weeks with three different diets: the standard diet (S), the standard diet supplemented with virgin olive oil (20%) (VOO), or the standard diet enriched with butter (20%) plus cholesterol (0.1%) (Bch). Kidney samples were separated in medulla and cortex for aminopeptidase activities (AP) assay. Urine samples were collected for routine analysis by chemical tests. Aminopeptidase activities were determined by fluorometric methods in soluble (sol) and membrane-bound (mb) fractions of renal tissue, using arylamide derivatives as substrates. After the experimental period, the systolic blood pressure (SBP) values were similar in standard and VOO animals, and significantly lower than in the Bch group. At the same time, a significant increase in GluAP and IRAP activities were found in renal medulla of Bch animals. However, in VOO group the increase of GluAP activity in renal medulla was lower, while AspAP activity decreased in the renal cortex. Furthermore, the VOO diet also affected other aminopeptidase activities, such as TyrAP and pGluAP, related to the regulation of the sympathetic nervous system and the metabolic rate. These results support the beneficial effect of VOO in the regulation of SBP through changes in local AP activities of the kidney.     

Self-condensing vinyl polymerization of acrylamide

Summary A novel approach to branched polyacrylamide was described. The branched structure resulted from the amidyl radicals which were formed by the reaction of amide groups with Cu(III) of potassium diperiodatocuprate, K₅[Cu(HIO₆)₂], in alkaline medium and capable of initiating the vinyl polymerization of acrylamide monomer. The obtained polymer was characterized by ¹H NMR, FT-IR and intrinsic viscosity measurements. Received: 8 January 1999/Revised version: 26 May 1999/Accepted: 25 June 1999     

荧光标识丙烯酰胺单体的合成

以邻氨基苯酚、对氨基苯甲酸和丙烯酰氯为原料,以多聚磷酸为脱水剂、三乙胺为脱酸剂,研制了一种新的荧光丙烯酰胺单体N-[4-(苯并唑-2-)苯基]丙烯酰胺(BPAA)。采用红外分析、核磁分析、紫外吸收、双键含量测定等方法对BPAA的结构进行了分析和确定,采用荧光测试对该荧光单体的荧光性能进行了研究。结果表明BPAA具有很强的荧光强度,而且其荧光性能对环境的敏感性较低。