Measurements of size-segregated emission particles by a sampling system based on the cascade impactor

A special sampling system for measurements of size-segregated particles directly at the source of emission was designed and constructed. The central part of this system is a low-pressure cascade impactor with 10 collection stages for the size ranges between 15 nm and 16 microm. Its capability and suitability was proven by sampling particles atthe stack (100 degrees C) of a coal-fired power station in Slovenia. These measurements showed very reasonable results in comparison with a commercial cascade impactor for PM10 and PM2.5 and with a plane device for total suspended particulate matter (TSP). The best agreement with the measurements made by a commercial impactor was found for concentrations of TSP above 10 mg m(-3), i.e., the average PM2.5/PM10 ratios obtained by a commercial impactor and by our impactor were 0.78 and 0.80, respectively. Analysis of selected elements in size-segregated emission particles additionally confirmed the suitability of our system. The measurements showed that the mass size distributions were generally bimodal, with the most pronounced mass peak in the 1-2 microm size range. The first results of elemental mass size distributions showed some distinctive differences in comparison to the most common ambient anthropogenic sources (i.e., traffic emissions). For example, trace elements, like Pb, Cd, As, and V, typically related to traffic emissions, are usually more abundant in particles less than 1 microm in size, whereas in our specific case they were found at about 2 microm. Thus, these mass size distributions can be used as a signature of this source. Simultaneous measurements of size-segregated particles at the source and in the surrounding environment can therefore significantly increase the sensitivity of the contribution of a specific source to the actual ambient concentrations.     

Adsorption characteristics of various proteins to a titanium surface

Adsorption characteristics of 18 proteins, with different sizes and isoelectric points, to a titanium oxide surface were studied. The adsorption isotherms were categorized based on protein type and pH: type 1, irreversible adsorption; type 2, Langmuir-type reversible adsorption; and type 3, reversible and irreversible adsorption. Most of the proteins tested were irreversibly adsorbed in the pH range of 3-8, whereas most adsorbed reversibly at pH 8.5-9.4. Protamine, with a pI value of 12, adsorbed reversibly in the pH range of 3-9. pH values that gave maximal sums of irreversibly and reversibly adsorbed proteins were in the pH range of 3-8 and tended to increase slightly with the pI value of the corresponding protein. pH values that gave maximal quantities of irreversibly adsorbed protein ranged between 4-6 and were nearly independent of pI.     

我国不同品种黄牛肉质研究概述

我国黄牛品种较多,了解其牛肉本质特性对于优质黄牛资源的开发利用具有重要意义。该文就我国不同品种肉用黄牛及其杂交牛的肉品品质进行了总结,包括其肉色和嫩度等食用品质及蛋白质、脂肪、氨基酸、脂肪酸、矿物质与维生素等营养品质。我国黄牛(尤其是杂交肉牛品种)食用品质较好,具有高蛋白低脂肪、富含矿物质、氨基酸评价优良等特征,但是不同品种之间的脂肪酸的含量及组分等信息匮乏,亟需开展大量的系统性研究工作填补这一空白。     

Modelling of rheological characteristics of various spaghetti types

Spaghetti enriched with resistant starch was produced to increase the dietary fibre intake of consumers. In the product base it was compared to bran and control spaghetti regarding to viscoelastic properties. Viscoelastic properties were tested by relaxation and creep tests by using TA-XT2i texture analyser. The viscoelastic properties gave structural information. Relaxation and creep data were analysed by generalized Maxwell (two- and three-termed), Peleg & Normand, Burgers and Peleg models, respectively. For relaxation three-termed Maxwell and for creep behaviour Burgers model represented viscoelastic behaviour satisfactorily. In general, bran spaghetti was found to have the lowest elasticity. All the samples started to loose their elasticity as cooking time proceeded and it became easy to deform them. Instrumentally, spaghetti with resistant starch was found to be better than bran enriched spaghetti.     

不同品种高粱糊化特性研究

为研究高粱糊化特性,以不同品种高粱为原料,采用Brabender型粘度仪描绘出粘度曲线,测评不同品种高粱糊化特性各项指标;结果表明,不同品种高粱由于其淀粉组成、结构、性质不同,具有不同糊化特性。     

Quantifying and mapping the spatial distribution of fluence inside a pulsed light treatment chamber and various liquid substrates

Pulsed light (PL) is a technology that uses short, high-energy pulses of UV-rich broad spectrum light to inactivate a range of pathogenic and spoilage microorganisms in foods and on food contact surfaces. Microbial inactivation is directly related to the energy dose (fluence) received by the target microbes. Since fluence decays away from the lamp source due to light absorption and scattering phenomena, it is necessary to accurately quantify the fluence received locally within a substrate in order to design uniform antimicrobial PL treatments. The main objective of this work was to quantify and map the spatial distribution of both total and UV fluence both in air and in liquid substrates with different optical properties. Butterfield’s phosphate buffer (BPB), trypticase soy broth (TSB), and apple juice (clarified apple cider) were used as substrates and Listeria innocua was used as the challenge microorganism. A pyroelectric head, and a UV-VIS-NIR spectrophotometer connected to a 1000 μm optical fiber, were used to measure the fluence in air and the three liquid substrates. Fluence was measured at incremental distances from the lamp, along the x-, y- and z-axes. As expected, fluence decreased with increasing distance from the lamp, in all three directions. A 3-parameter Gaussian model described well the spatial distribution of fluence, both in air and in the liquid substrates. Overall, this study emphasizes the fact that substrate-light interactions affect the spatial distribution of fluence within a substrate, and these non-uniformities need to be taken into account when developing commercial applications of PL.     

湖南不同类型刺葡萄植物学性状研究

本试验收集了湖南省内的20份刺葡萄种质资源,利用Galet葡萄叶形特征值编码方法,发现高山2号与木叶溪刺葡萄的编码值一样,为证明湘西的高山2号刺葡萄与从木叶溪筛选出的紫秋2号是同一个类型的说法提供了依据。同时将叶形特征值结合果实性状运用DPS数据处理软件进行UPGMA聚类分析,进一步证明了白刺葡萄即水晶刺葡萄与其它刺葡萄的亲缘关系较远,为一新的刺葡萄类型。     

Use of energy substrates by various stage preimplantation pig embryos produced in vivo and in vitro

The aim of in vitro embryo systems is to produce embryos of comparable quality to those derived in vivo. Comparison of embryo metabolism as an indicator of viability may be useful in optimization of culture conditions. The aim of the present study was to determine glucose, glutamine and pyruvate use by various stage pig embryos produced in vitro and in vivo. The results indicate that pig embryos use glucose via glycolysis in significant amounts at all stages examined, regardless of embryo origin. In vitro-derived embryos have significantly increased glycolytic activity after the eight-cell stage, whereas in vivo-derived embryos have increased glycolysis at the blastocyst stage. In vivo-derived embryos have higher rates of glycolysis compared with in vitro-derived embryos. Glucose usage through the Krebs cycle for in vitro- and in vivo-derived embryos increased significantly at the blastocyst stage. Pig embryos produced in vitro used constant amounts of glutamine throughout development, whereas in vivo-derived embryos increased glutamine usage after the eight-cell stage. Pyruvate use was minimal at all stages examined for both in vitro- and in vivo-derived pig embryos, showing significant increases at the blastocyst stage. Krebs cycle metabolism of pyruvate, glutamine and glucose by in vivo-derived embryos was higher than that by in vitro-derived embryos. Current in vitro culture conditions produce pig embryos with altered metabolic activity, which may compromise embryo viability.     

Quality characteristics of vacuum-fried snacks prepared from various sweet potato cultivars

The effects of vacuum frying and atmospheric frying on the physicochemical properties and quality characteristics of the deep-fat-fried snacks were compared in manufacturing snacks using general, yellow-fleshed, and purple-fleshed sweet potatoes. Regarding the moisture and lipid content of snacks, vacuum-fried snacks showed about 50% lower values compared to atmospheric-fried snacks, while for the colors, vacuum-fried snacks showed higher L and b values and a slightly lower a value, with almost no difference in the texture, compared to atmospheric-fried snacks. The total carotenoid and anthocyanin contents of snacks were decreased greatly compared to fresh sweet potatoes, and was considerably higher in vacuum-fried snacks compared to atmospheric-fried snacks. For the sensory evaluation of snacks, the acceptability for color and flavor was higher in the vacuum-fried snacks, while the acceptability for texture was higher in atmospheric-fried snacks due to a higher degree of crispiness. In conclusion, it is considered that the vacuum frying in manufacturing sweet potato snacks, compared to the atmospheric frying, is the appropriate deep-fat frying method for modern people who take excessive fats and oils from foods and are highly interested in health and high quality products.     

Emission characteristics of carbonaceous particles from various residential coal-stoves in China

China is thought to be the most important contributor to the global burden of carbonaceous aerosols, and residential coal combustion is the greatest emission source of black carbon (BC). In the present study, two high-efficiency household coal-stoves are tested together with honeycomb-coal-briquettes and raw-coal-chunks of nine different coals. Coal-burning emissions are collected onto quartz fiber filters (QFFs) and analyzed by a thermal-optical transmittance (TOT) method. Emission factors (EFs) of particulate matter (PM), organic carbon (OC), and elemental carbon (EC) are systematically measured, and the average EFs are calculated by taking into account our previous data. For bituminous coal-briquette and -chunk, EFs of PM, OC, and EC are 7.33, 4.16, and 0.08 g/kg and 14.8, 5.93, and 3.81 g/kg, respectively; and for anthracite-briquette and -chunk, they are 1.21, 0.06, and 0.004 g/kg and 1.08, 0.10, and 0.007 g/kg, respectively. Annual estimates for PM, OC, and EC emissions in China are calculated for the years of 2000 and 2005 according to the EFs and coal consumptions, and the results are consistent with our previous estimates. Bituminous coal-chunk contributes 68% and 99% of the total OC and EC emissions from household coal burning, respectively. Additionally, a new model of Aethalometer (AE90) is introduced into the sampling system to monitor the real-time BC concentrations. On one hand, AE90 provides a set of EFs for optical BC in parallel to thermal-optical EC, and these two data are generally comparable, although BC/EC ratios vary in different coal/stove combinations. On the other hand, AE90 offers a chance to observe the variation of BC concentrations during whole burning cycles, which demonstrates that almost all BC emits into the flue during the initial period of 15 min after coal addition into household stoves.     

Degradation characteristics of proteins in cheonggukjang (fermented unsalted soybean paste) prepared with various soybean cultivars

In order to select the most ideal soybean cultivars for producing cheonggukjang, the protein degradation characteristics of cheonggukjangs prepared with 30 different soybean cultivars were compared. Cheonggukjang prepared with ‘Nampung’ (18.00±0.28%) and ‘Sohwang’ (17.91±0.63%) soybeans showed the highest contents of viscous substances. Acidic-protease activity was highest (590.24±2.92 μg/mL) in cheonggukjang prepared with small ‘Pungsannalmul’ soybeans. Neutral-protease activity was highest (528.13±3.11 and 527.36±0.44 μg/mL, respectively) in cheonggukjang prepared with ‘Singi’ and ‘Nampung’ soybeans. Cheonggukjang prepared with ‘Wonkwang’ and ‘Sohwang’ soybeans had amino-type nitrogen contents of 780.50±2.92 and 729.95±1.07 mg%, respectively. Glutamic acid, which is a major component of viscous substances, was also detected. Although total free amino acid levels in cheonggukjang prepared with ‘Daewon’ and ‘Wonkwang’ soybeans measured 2,551.21 and 2,340.02 mg%, respectively, cheonggukjang prepared with black soybeans exhibited low levels of total free amino acids. Therefore, based on protein degradation characteristics, large ‘Daewon’ soybeans and small ‘Wonkwang’ soybeans were the most suitable for producing cheonggukjang.     

Microencapsulation of Lactobacillus acidophilus ATCC 43121 with prebiotic substrates using a hybridisation system

The objective of this study was to evaluate the effects of prebiotic substrates on the growth of Lactobacillus acidophilus ATCC 43121 and to investigate the utilisation of these prebiotic substrates as coating materials for microencapsulation. The cell growth of L. acidophilus ATCC 43121 was significantly increased in the presence of fructooligosaccharide, lactulose and raffinose. The microencapsulation of L. acidophilus ATCC 43121 cells was carried out by dry surface reforming process (hybridisation) using the selected prebiotic substrates and the enteric coating material, Sureteric^TMsans. Scanning and transmission electron microscopy revealed that the double‐microencapsulated bacteria exhibited smooth, rounded external surfaces, with a thick external coating composed of the prebiotic substrates and the Sureteric. The acid (artificial gastric juice) or heat tolerance (55 °C) of the double‐microencapsulated preparations (prebiotic and enteric coating) was significantly higher than that of the uncoated and single‐coated (enteric coating) preparation at prolonged acid (5 h) or heat exposure (3 h). On the contrary, no significant differences were found in salt tolerance. During the storage up to 20 days at 25 and 37 °C, the stability of L. acidophilus ATCC 43121 was significantly improved by double‐microencapsulation.     

Fat spectro-colorimetric characteristics of lambs switched from a low to a high dietary carotenoid level for various durations before slaughter

This study investigated the changes in fat reflectance spectrum characteristics and color in lambs switched from a low to a high dietary carotenoid level for various durations before slaughter. Six treatments, feeding a high dietary carotenoid level for 0, 15, 30, 45, 60 or 75days before slaughter, were compared in individually indoor penned lambs. Each treatment used 10 Romane lambs; feeding management ensured similar growth pattern and carcass weight for all the treatment groups. There was a change in reflectance spectrum characteristics and yellowness of subcutaneous fat as early as 15days after the switch. Mean concentration of carotenoid pigments and yellowness of subcutaneous fat increased linearly with the duration of the high dietary carotenoid level. In perirenal fat, the change in reflectance spectrum characteristics was observed as early as 15days after the switch, but the response to the duration of the high dietary carotenoid level was curvilinear.     

不同品种粳米-低筋小麦混合粉体系粉质特性研究

采用市售低筋粉分别与5种粳米粉组成混合粉体系,对其粉质和拉伸特性变化规律,及其与各品种粳米粉的组成成分的相关性进行分析。结果表明:随粳米粉添加量的增加,吸水率以及拉伸比值整体呈上升变化趋势;面团形成时间、稳定时间、评价值以及面团抗拉伸阻力整体略呈下降变化趋势;延伸性呈显著性下降;弱化度整体先升高后降低。当粳米粉添加量不同时,除蛋白质和灰分外的其它组分均与粳米-低筋小麦混合粉面团的各项粉质特性参数指标呈现显著相关性。     

传统风鸭产品特性分析

对传统风鸭产品的产品特性进行分析,结果表明,风鸭肉是一种高蛋白低脂肪的营养肉制品,其蛋白质和脂肪含量分别为27.75%和4.47%。风鸭肉Aw为0.86,鸭皮Aw为0.72,属于Aw值低于0.90的半干食品,具备良好的非制冷可贮性。风鸭产品中游离脂肪酸总含量为1.452%,显著高于鲜鸭(0.216%)。虽然其不饱和脂肪酸含量略低于鲜鸭,但差异不显著,而其必需脂肪酸的含量较鲜鸭高3.74%。风鸭中游离氨基酸总量为29.4%,显著高于鲜鸭(22.1%)。风鸭中含有Lys、Leu、Ile、Met、Phe、Thr、Val、His必需氨基酸,未检出Tre,其必需氨基酸总量为10.99%,高于鲜鸭。与氨基酸需要量模式相比,风鸭产品中的氨基酸含量较低,但除了色氨酸未检出外,风鸭产品中必需氨基酸的含量比与氨基酸模式很接近。     

不同粒径聚酯底物的微生物降解

为研究形态结构对高聚物底物生物反应性的影响,分别以不同粒径的聚酯粉末为唯一碳源培养菌种,通过检测菌株生物量、发酵液中产物种类与浓度以及聚酯底物结晶度变化,研究菌株对底物尺寸结构的生物反应性影响。结果表明:以粒径小的粉末作为底物时,菌株的生长速率和生物量都远大于底物粒径较大的情况;在培养过程中,不同粒径底物发酵液中产物种类不尽相同,产物浓度的变化规律不同;菌株更易降解小粒径颗粒,且主要作用于无定形区域。     

Development of a methyl bromide collection system for fumigated farmland

Recent research has indicated that up to 73% of the methyl bromide (MeBr) applied to agricultural farmland is ultimately emitted to the atmosphere despite the practice of complete coverage of the fields with polyethylene (PE) tarp. To reduce the emission of MeBr, several techniques have been investigated. An alternative that has received little consideration is the collection and recycle or treatment of MeBr emissions. We investigated the potential of using a two-layer tarp system for collecting the MeBr. Laboratory experiments with a small two-layer diffusion reactor were conducted to determine the mass transfer coefficient (K) of MeBr through tarps and to validate a model of the collection system. For PE tarps K was 1.15 x 10(-6) m s-1 at 20 degrees C and 5.2 x 10(-6) m s-1 at 60 degrees C. K for so-called virtually impermeable films ranged from 4.6 x 10(-10) m s-1 to 1.3 x 10(-8) m s-1. The mathematical model was then used to simulate a full scale fumigant field application. Results indicate excellent agreement between the model, laboratory experiments, and previous field studies. Total emission from the field was a function of the air exchange rate through the swept volume between the two layers, the length of time the field is covered by the collection system, and the mass transfer coefficient of MeBr though the tarps. The results indicate that the proposed two-layer system can be very effective in collecting MeBr emissions from fumigated farmland.