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.     

磁控溅射纳米膜与不同纺织基材的结合牢度

针对天然纤维基材上磁控溅射纳米膜易整层脱落问题,系统测试了不同纤维基材上磁控溅射结构生色膜的耐摩擦色牢度和耐皂洗色牢度,研究了样品的初始含水率和低温等离子体表面改性对磁控溅射膜与纤维基材结合牢度的影响,进而借助扫描电子显微镜并结合纤维材料的理化性能分析得出磁控溅射膜与各种纺织基材结合牢度不同的原因。结果表明:热塑性的涤纶存在软化点,磁控溅射高能粒子沉积到纤维表面时动能转化为热能,使涤纶局部达到软化点,粘结溅射粒子;棉和蚕丝没有软化点,纤维对磁控溅射粒子无熔融粘结作用,且棉和蚕丝具有高吸湿溶胀性,皂洗过程中水分子的侵入削弱纤维和纳米粒子间的作用力,致使磁控溅射膜易脱落。     

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.     

非对称润湿特性纺织基材上高稳固光子晶体的构筑

为提升纺织基材上光子晶体结构色的耐久性,从印花色浆性能和基材润湿性2个角度切入,以具有自交联特性的聚(苯乙烯-N-羟甲基丙烯酰胺)(P(St-NMA))胶体微球为主要成分制备印花色浆,采用丝网印花法在具有非对称润湿特性的纺织基材上构筑光子晶体生色结构,并测试制备所得光子晶体在纺织基材上的稳固性。结果表明：当印花色浆中微球质量分数为80%、自交联促进剂盐酸质量分数为5%～10%时,有助于得到结构色鲜艳且结构稳固的光子晶体;采用等离子体技术可实现纺织基材的非对称润湿特性,当处理时间为3 min时,可得到正、反面接触角为56°和110°的纺织基材,且在此基材正面构筑得到的光子晶体能够兼顾结构色效果和结构稳固性。     

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。     

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.     

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。     

南美白对虾酚氧化酶催化不同底物的生化特性研究

为揭示南美白对虾酚氧化酶（phenoloxidase,PO）催化不同底物时的生化特性,本文以L-多巴、甲基多巴、邻苯二酚为底物,分别测定南美白对虾酚氧化酶催化这三种底物时的最适温度、最适p H,酶促动力学常数K_m、V_max值、活化能。结果表明,南美白对虾PO酶催化三种底物的最适温度分别为45、40、30℃,最适p H分别为6.8、7.2、8.0,酶促动力学常数K_m分别为2.5003、5.8661、1.8429 mmol/L,V_max分别为0.0624、0.1008、0.1692ΔA/min,活化能Ea分别为15.2158、18.1981、10.4696 k J/mol;邻苯二酚与PO酶的结合能力较强,但其结合受外界温度的影响较大;而PO酶与L-多巴和甲基多巴的结合受外界温度影响较小。由此可得,底物结构越简单,越容易与PO酶活性中心结合;底物与酶的结合能力越强,酶活化底物时所需的活化能越小;在PO酶研究中,如果影响因素有温度这一条件时,不应该选择邻苯二酚作为底物。      

芽苗菜集硒特性及富硒芽苗菜生理活性研究进展

硒是人体的必需微量元素,具有抗氧化、抗癌等多种生理活性,缺硒往往导致慢性疾病的发生。发芽富硒培育是提高芽苗菜硒含量的有效途径。芽苗菜具有较强的无机硒富集和转化能力,且因资源丰富、生物利用度高而备受消费者欢迎。众多研究表明,富硒之后的芽苗菜在生长特性、营养物质、生理活性等方面都得到显著提高。本文对芽苗菜的集硒途径、集硒条件、富硒芽苗菜的生理活性等方面的研究现状进行了综述,在此基础上探讨了富硒芽苗菜的发展前景,以期为富硒芽苗菜的开发利用提供一定的理论支撑。     

The functional, rheological and sensory characteristics of ice creams with various fat replacers

The effects of fat replacers (Simplesse® D-100, N-Lite D, and inulin) on the melting characteristics, overruns, hardness, rheological parameters and sensory attributes of reduced (RF, 60.0 g/kg), low (LF, 40.0 g/kg), and nonfat (NF, 1.0 g/kg) ice creams were investigated. The magnitudes of the melting rates were in the order RF>LF>NF for samples that contained Simplesse® D-100 or inulin, but the reverse order was found for samples with N-Lite D. The nonfat ice creams had lowest overrun values of around 10%. Inulin-containing ice creams possessed higher overrun values than others ( P  > 0.05). The use of fat replacer decreased the hardness of ice creams. All ice cream samples showed pseudoplastic (shear-thinning) behavior. The addition of N-Lite D and inulin decreased the flow behaviour index of ice cream samples. The reduced and low fat ice cream samples were rated as similar to the control by a sensory panel. On the other hand, no correlations ( P  > 0.05) were observed between rheological parameters and sensory texture and mouthfeel.     

The relationship of textural characteristics with composition of sandesh produced from various market milk classes

The texture of sandesh an Indian milk‐based sweetmeat, was characterised by instrumental means and interrelationships among textural parameters and composition were studied. Hardness, fracturability, chewiness and adhesiveness was highest for sandesh prepared from milk containing 6% fat, 9% SNF and lowest for sandesh prepared from milk containing 1.5% fat, 9% SNF. Hardness of sandesh was significantly positively (P < 0.01) correlated with the fat content but negatively (P < 0.01) correlated with moisture and ash. Moisture and fat had negative and positive correlation (P < 0.01) with fracturability, respectively. Ash and moisture had a positive (P < 0.01) influence on resilience whereas fat had a negative influence. Cohesiveness was not influenced by composition parameters. Springiness had positive and negative correlation (P < 0.05) with fat and moisture, respectively. Gumminess followed similar pattern to that of hardness. Moisture and fat had negative and positive effect respectively (P < 0.01) on adhesiveness. Chewiness was negatively and positively influenced (P < 0.01) by moisture and fat of sandesh, respectively.     

Physicochemical characteristics of Ethiopian Coffea arabica cv. Heirloom coffee extracts with various roasting conditions

This study aimed to investigate the physicochemical characteristics of Ethiopian Coffea arabica cv. Heirloom coffee extracts with various roasting conditions. Green coffee beans were roasted at four different conditions (Light-medium, Medium, Moderately dark, and Very dark) and used to extract espresso and drip coffee. Moisture content in coffee beans was decreased as the roasting degree increased. The contents of crude fat and ash were lower in the Light-medium roasted coffee beans than in green coffee beans but increased as the roasting degree increased. The values of lightness (L^*), redness (a^*), yellowness (b^*), and browning index of coffee extracts were decreased as the roasting degree increased. Total dissolved solids in espresso coffee were increased with increasing roasting degree but decreased in drip coffee. In both the extracts, the contents of reducing sugar, titratable acidity, organic acids, and chlorogenic acid were decreased, but that of caffeine was increased with the roasting degree increased.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-020-00865-w.     

Physical and sensory characteristics and probiotic survival in ice cream sweetened with various polyols

The effect of polyols (xylitol, erythritol, maltitol and isomalt) on physical and sensory properties of probiotic ice cream, as well as the survival of Bifidobacterium BB‐12 during freezing over 28 days of frozen storage, was investigated. The control sample of ice cream, sweetened with sugar, showed a lower pH and higher overrun than those sweetened with polyols. The viable bifidobacteria counts remained above 8 log cfu/g in all samples. The amount of erythritol added was not enough to obtain a similar sweetness as in control, but too high to get an ice cream with good textural properties.     

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.     

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。     

3D enabled facile fabrication of substrates with human tongue characteristics for analysing the tribological behaviour of food emulsions

The mouth-feel or oral perception of a food may vary in different oral surfaces or tongue-palate environment depending on the physical characteristics of human tongue. Tribological measurements emulating the characteristics of tongue-palate environment will assist in the evaluation of oral perception of food materials. This study reports a 3D printing assisted approach for rapid fabrication of the soft elastomer substrates with different surface (roughness) and bulk characteristics (elastic modulus and thickness) for tribological measurements. The influence of substrates with various regularly patterned surfaces, elastic modulus, and thickness on the lubrication properties of four food emulsions (full-fat and skim milk, high-fat and low-fat yoghurt) has been investigated. It is observed that friction coefficient of food emulsions increases with a decrease in height or an increase in density of rectangular micro-scale pillars representing papillae on the surface of soft substrate. Interestingly, a decrease in the elastic modulus of the substrates causes an increase in the friction coefficient for the milk samples, whereas for yoghurt samples it causes a decrease. The variations in the thickness of the substrates have little effect on the friction coefficients of the food emulsions.