青岛近海主要海捕水产品中金属元素与石油烃含量分析

目的对青岛近海主要海捕水产品开展质量安全与营养评价研究,掌握捕捞水产品的食用安全现状。方法全面分析青岛近海海域主要捕捞水产品中常量元素、微量元素、稀土元素以及石油烃的含量,并进行食用安全评价分析。结果研究表明青岛近海海域水产品中含有丰富的人体必需元素,是补充人体矿物质营养的良好膳食来源。稀土元素总含量为6.08~232μg/kg,且甲壳类高于鱼类。水产品中鱼类的有害微量元素及石油烃含量均符合我国水产品有毒有害物质限量标准,但甲壳类中梭子蟹和虾蛄的镉(Cd)和少数样品中石油烃含量存在超标情况。结论亟需进一步加强水产品中有害元素的形态分析研究,科学开展风险评估。     

Volatile disinfection byproduct formation resulting from chlorination of organic-nitrogen precursors in swimming pools

Clinical studies have documented the promotion of respiratory ailments (e.g., asthma) among swimmers, especially in indoor swimming pools. Most studies of this behavior have identified trichloramine (NCl3) as the causative agent for these respiratory ailments; however, the analytical methods employed in these studies were not suited for identification or quantification of other volatile disinfection byproducts (DPBs) that could also contribute to this process. To address this issue, volatile DBP formation resulting from the chlorination of four model compounds (creatinine, urea, L-histidine, and L-arginine) was investigated over a range of chlorine/precursor (Cl/P) molar ratios. Trichloramine was observed to result from chlorination of all four model organic-nitrogen compounds. In addition to trichloramine, dichloromethylamine (CH3NCl2) was detected in the chlorination of creatinine, while cyanogen chloride (CNCl) and dichoroacetonitrile (CNCHCl2) were identified in the chlorination of L-histidine. Roughly 0.1 mg/L (as Cl2) NCl3, 0.01 mg/L CNCHCl2, and 0.01 mg/L CH3NCl2 were also observed in actual swimming pool water samples. DPD/FAS titration and MIMS (membrane introduction mass spectrometry) were both employed to measure residual chlorine and DBPs. The combined application of these methods allowed for identification of sources of interference in the conventional method (DPD/FAS), as well as structural information about the volatile DBPs that formed. The analysis by MIMS clearly indicates that volatile DBP formation in swimming pools is not limited to inorganic chloramines and haloforms. Additional experimentation allowed for the identification of possible reaction pathways to describe the formation of these DBPs from the precursor compounds used in this study.     

Geochemical and strontium isotope characterization of produced waters from Marcellus Shale natural gas extraction

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ~375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ε(Sr)(SW) = +13.8 to +41.6, where ε(Sr) (SW) is the deviation of the (87)Sr/(86)Sr ratio from that of seawater in parts per 10(4)); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.     

解淀粉芽孢杆菌产葡甘聚糖酶的条件优化及酶学性质研究

为了优化解淀粉芽孢杆菌产葡甘聚糖酶的条件,在单因素试验的基础上,利用响应面法分析发酵条件,并研究葡甘聚糖酶的酶学性质。结果表明,解淀粉芽孢杆菌产葡甘聚糖酶的最佳培养基成分为葡萄糖40 g/L、酵母粉9 g/L、硫酸铵0.8 g/L;最佳发酵条件为温度30℃、发酵时间80 h、接种量8%(体积分数)、装液量100 m L/250 m L,在此条件得到的葡甘聚糖酶活力可达2 509 U/m L。该葡甘聚糖酶的最适反应条件为50℃、pH 7;在30～40℃、p H 3～7酶活力稳定; Al~(3+)、Fe~(3+)、Cu~(2+)等离子对葡甘聚糖酶有抑制作用,Mn~(2+)有激活作用。     

姜酚生产回收液与生姜中风味物质的比较

工业化提取生姜辣味物质后产生大量的酒精回收液,为探索该回收液与生姜中风味物质的差别,采用气质联用仪分离并鉴定两种样品中主要的风味物质成分。通过比较发现酒精回收液中不含有6-姜酚,但含有许多生姜中的其它风味物质,为有效的利用姜酚生产酒精回收液中的风味物质提供了依据。     

Volatile profile and microbiological characterization of hollow defect in dry-cured ham

This paper describes the physicochemical and microbiological parameters and volatile profile of the muscles surrounding the coxofemoral joint which are affected with hollow defect when compared to the part of muscles nearby which did not show this defect. Differences of the same parameters between both areas in dry-cured hams without this defect were also analyzed. Gram-positive catalase-positive cocci were the predominant flora in the muscles affected with hollow defect, with the main species being Staphyloccocus equorum, Staphylococcus nepalensis and Staphylococcus xylosus. Lactic acid bacteria, Listeria monocytogenes and Staphylococcus aureus were < 2 log CFU g^− 1 and Salmonella spp. was not detected. Volatile profile of samples affected with hollow defect had higher amounts of compounds such as esters, pyrazines, sulfurs and furans. There was a positive correlation between the amount of ester compounds and the hollow defect intensity. Moisture content was lower and pH values were higher in affected areas than in unaffected areas.     

Meaty flavour compounds formation from the submerged liquid culture of Pleurotus ostreatus

The capacity of oyster mushroom (Pleurotus ostreatus) mycelium to produce meaty flavour compounds in the presence of amino acids and sugars was studied. The submerged liquid culture of P. ostreatus mycelium along with base medium made of defatted soybean powder, sucrose, potassium phosphate, and magnesium sulphate was incubated for 3 days at 25 °C. Cysteine, glutamine, or methionine and fructose, galactose, ribose, or xylose were added to the base medium to study the effect of amino acids and sugars on meaty flavour formation by trained panelists. The flavour compounds were isolated and identified by GC–MS and GC retention time of authentic compounds. The base medium required P. ostreatus, cysteine, ribose, and heat treatment to produce meaty flavour. The sulphur containing heterocyclic compounds such as 2,5‐diethylthiophene, 2‐formyl‐5‐methylthiophene, 3‐ethyl‐2‐formylthiophene, and dimethylformyl thiophene were responsible for meaty flavour. These compounds were formed by non‐enzymatic browning reaction between ribose and cysteine during heat treatment.     

Mitigation of methane production from cattle by feeding cashew nut shell liquid

The effects of cashew nut shell liquid (CNSL) feeding on methane production and rumen fermentation were investigated by repeatedly using 3 Holstein nonlactating cows with rumen fistulas. The cows were fed a concentrate and hay diet (6:4 ratio) for 4 wk (control period) followed by the same diet with a CNSL-containing pellet for the next 3 wk (CNSL period). Two trials were conducted using CNSL pellets blended with only silica (trial 1) or with several other ingredients (trial 2). Each pellet type was fed to cows to allow CNSL intake at 4g/100kg of body weight per day. Methane production was measured in a respiration chamber system, and energy balance, nutrient digestibility, and rumen microbial changes were monitored. Methane production per unit of dry matter intake decreased by 38.3 and 19.3% in CNSL feeding trials 1 and 2, respectively. Energy loss as methane emission decreased from 9.7 to 6.1% (trial 1) and from 8.4 to 7.0% (trial 2) with CNSL feeding, whereas the loss to feces (trial 1) and heat production (trial 2) increased. Retained energy did not differ between the control and CNSL periods. Digestibility of dry matter and gross energy decreased with CNSL feeding in trial 1, but did not differ in trial 2. Feeding CNSL caused a decrease in acetate and total short-chain fatty acid levels and an increase in propionate proportion in both trials. Relative copy number of methyl coenzyme-M reductase subunit A gene and its expression decreased with CNSL feeding. The relative abundance of fibrolytic or formate-producing species such as Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, and Treponema bryantii decreased, but species related to propionate production, including Prevotella ruminicolla, Selenomonas ruminantium, Anaerovibrio lipolytica, and Succinivibrio dextrinosolvens, increased. If used in a suitable formulation, CNSL acts as a potent methane-inhibiting and propionate-enhancing agent through the alteration of rumen microbiota without adversely affecting feed digestibility.     

以螺旋藻生化提取液制造螺旋藻啤酒的研究

螺旋藻是一种生长在热带、亚热带碱性湖泊中的微藻类植物。它含有丰富的蛋白质、叶绿素、γ-亚麻酸、β-胡萝卜素及维生素，且富含人体必需的8种氨基酸和钙、锌、铁、钾、镁、硒、磷等矿物质和微量元素。螺旋藻除具有丰富的营养之外，还被公认对人体有较强的保健作用，对多种病症有预防和辅助治疗作用，能够调节人体机能平衡，增强人体免疫力，且无任何副作用，因此螺旋藻被联合国粮农组织誉为“21世纪人类最理想的天然保健品”。     

Growth and hydrocarbon production of microalga Botryococcus braunii in bubble column photobioreactors

Microalga Botryococcus braunii, which produces high levels of liquid hydrocarbons called botryococcenes, was cultivated in bubble column photobioreactors. Algal cells, adapted to low irradiance (3 klx) in the preculture, showed lower biomass and hydrocarbons productivity in the photobioreactor illuminated at high irradiance (10 klx) due to the effects of photoinhibition. The degree of photoinhibition was reduced by partial shading, the lighted volume ratio being varied from 25 to 100%. The algal cells adapted to high irradiance in the preculture showed a high biomass productivity at 10 klx: the cell concentration reached higher than 7 kg/m3 and the hydrocarbon content was 50% based on cell dry weight. Hydrocarbon production kinetics of this alga in the linear growth phase was found to be growth-associated irrespective of the experimental conditions of illumination and preculture.     

Comprehensive characterization of the functional activities of pressurized liquid and ultrasound-assisted extracts from Chlorella vulgaris

Chlorella vulgaris has been referred as a potential source of bioactive compounds (carotenoids and fatty acids). In this work, the ability of an environmentally friendly extraction technique such as Pressurized Liquid Extraction (PLE) and a traditional extraction technique such as Ultrasound-Assisted Extraction (UAE) to obtain functional compounds from C. vulgaris, at analytical scale, has been demonstrated. Seeked bioactivities were antioxidant and antimicrobial, for their interest in the food industry. Therefore, a methodology including analytical extraction, in-vitro assays and chemical characterization via HPLC-DAD and GC–MS has been used to determine the interest of Chlorella as a source of functional food ingredients. Results demonstrated that PLE provide higher yields than UAE while similar bioactivities were obtained. Important concentration of carotenoids (lutein, neoxanthin, β-carotene, etc.), chlorophylls, sterols, phytols, and fatty acids (among others) have been found in Chlorella extracts that could be correlated to the observed biological activity.     

Iodate and iodo-trihalomethane formation during chlorination of iodide-containing waters: role of bromide

The kinetics of iodate formation is a critical factor in mitigation of the formation of potentially toxic and off flavor causing iodoorganic compounds during chlorination. This study demonstrates that the formation of bromine through the oxidation of bromide by chlorine significantly enhances the oxidation of iodide to iodate in a bromide-catalyzed process. The pH-dependent kinetics revealed species specific rate constants of k(HOBr + IO(-)) = 1.9 × 10(6) M(-1) s(-1), k(BrO(-) + IO(-)) = 1.8 × 10(3) M(-1) s(-1), and k(HOBr + HOI) < 1 M(-1) s(-1). The kinetics and the yield of iodate formation in natural waters depend mainly on the naturally occurring bromide and the type and concentration of dissolved organic matter (DOM). The process of free chlorine exposure followed by ammonia addition revealed that the formation of iodo-trihalomethanes (I-THMs), especially iodoform, was greatly reduced by an increase of free chlorine exposure and an increase of the Br(-)/I(-) ratio. In water from the Great Southern River (with a bromide concentration of 200 μg/L), the relative I-incorporation in I-THMs decreased from 18 to 2% when the free chlorine contact time was increased from 2 to 20 min (chlorine dose of 1 mg Cl(2)/L). This observation is inversely correlated with the conversion of iodide to iodate, which increased from 10 to nearly 90%. Increasing bromide concentration also increased the conversion of iodide to iodate: from 45 to nearly 90% with a bromide concentration of 40 and 200 μg/L, respectively, and a prechlorination time of 20 min, while the I-incorporation in I-THMs decreased from 10 to 2%.     

新型液晶高分子聚合物的合成与表征

合成了丙烯酸异山梨醇双酯和4-(丙烯酸乙氧基酯)苯甲酸胆甾醇酯液晶中间体,经红外光谱、核磁共振氢谱和元素分析确认其结构。通过聚合反应将丙烯酸六氟丁酯引入并合成了4-(丙烯酸乙氧基酯)苯甲酸胆甾醇酯基元含氟侧链高分子液晶,采用红外光谱、核磁共振氢谱和氟谱表征了该液晶的分子结构。通过DSC和偏光显微镜分析这种高分子液晶的玻璃化温度、清亮点及相变区间,结果表明,该液晶具有玻璃化温度、清亮点低,相变区间窄的特点,且随着丙烯酸六氟丁酯成分的增加,高分子液晶的玻璃化温度略有增加。     

三硅氧烷型吡啶类离子液体表面活性剂的合成与表征

通过两步法制备了一种三硅氧烷型吡啶类离子液体表面活性剂([Si(3)Py]Cl),用IR、1H NMR和13C NMR对产物的结构进行表征,表面活性和聚集行为通过表面张力仪、动态光散射(DLS)和负染色透射电镜(TEM)进行测量.结果表明:[Si(3)Py]Cl具有良好的表面活性,其cmc为24.81 mmol/L,γcmc为23.04 mN/m,在水溶液中能聚集成直径为50~100 nm的囊泡.     

Detection of protozoan parasites and microsporidia in irrigation waters used for crop production

The occurrence of human pathogenic parasites in irrigation waters used for food crops traditionally eaten raw was investigated. The polymerase chain reaction was used to detect human pathogenic microsporidia in irrigation waters from the United States and several Central American countries. In addition, the occurrence of both Cryptosporidium oocysts and Giardia cysts was determined by immunofluorescent techniques. Twenty-eight percent of the irrigation water samples tested positive for microsporidia, 60% tested positive for Giardia cysts, and 36% tested positive for Cryptosporidium oocysts. The average concentrations in samples from Central America containing Giardia cysts and Cryptosporidium oocysts were 559 cysts and 227 oocysts per 100 liters. In samples from the United States, averages of 25 Giardia cysts per 100 liters and <19 (average detection limit) Cryptosporidium oocysts per 100 liters were detected. Two of the samples that were positive for microsporidia were sequenced, and subsequent database homology comparisons allowed the presumptive identification of two human pathogenic species, Encephalitozoon intestinalis (94% homology) and Pleistophora spp. (89% homology). The presence of human pathogenic parasites in irrigation waters used in the production of crops traditionally consumed raw suggests that there may be a risk of infection to consumers who come in contact with or eat these products.