纳米生色面料的防水透气性能与抗菌性能

简述了纳米生色技术的原理,归纳了纳米生色技术的6大优势;给出了纳米生色面料防水透气性能和抗菌性能的实验结果。与传统方法比较,纳米生色面料的防水透气性能与抗菌性能是该技术赋予面料本身的自然属性,并没有做专门的处理,既绿色环保,又有很高的性价比,为纳米生色面料的大面积推广应用奠定了基础。     

Reducing drag force on polyester fabric through superhydrophobic surface via nano-pretreatment and water repellent finishing

Energy saving is a very important factor for athletics that works in high speed and award winning competition. Drag force is of prime importance for determining the speed of objects that moves in the fluid. Nanotechnology is of great potential among the methods for reducing drag force. Enhancing the fabric speed in the fluids could be achieved using superhydrophobic surfaces to reduce the drag force. A simple and versatile method was utilized for the fabrication of superhydrophobic surfaces via pad-dry-cure and in situ synthesis of ZnO nanoparticles as a pre-treatment. The treated samples were examined by SEM for assessing the structure and size of nanoparticles and mapping and EDX analysis was carried out for further characterization. A novel method was designed based on the tensile tester apparatus for studying the changes in drag force. The results indicated a reduction of 80% in drag force of the treated fabric in the optimum conditions of pre-treatment with 10% zinc nitrate (Zn(NO₃)₂) and 5% sodium hydroxide (NaOH) at 130 °C for 1 h.     

近代工艺和变速控制技术融合 降低抄纸机真空系统的能耗

介绍由可变速控制的真空泵-生态透平泵构建的纸机新真空系统的优越性和可行性,投资省而且回收率高,比以往水环式真空泵或多段式透平风机系统节能30%~60%,并大大节约用水。文中有应用实例和流程说明。     

亚麻织物接枝率与透气率变化关系的数学模型

 摘 要 ： 本设计通过紫外光引发接枝丙烯酸对亚麻织物进行改性处理。应用BP神经网络法和最小二乘回归法分别对不同光照接枝时间、光引发剂用量、单体浓度下的织物接枝率与透气率变化量之间关系进行建模。将接枝率作为输入、透气率变化量作为输出,通过讨论确定神经网络结构为1-10-1,S型函数作为激活函数;同时选出最优网络参数即迭代次数100、训练目标0.001。BP 网络模型与最小二乘模型相比,仿真输出与目标输出相关系数高,误差百分比小。因此,BP神经网络模型具有更好的仿真精度,为接枝率和透气率间关系的探索提供了一种准确有效的预测模型。     

Short communication: Effects of changing teatcup removal and vacuum settings on milking efficiency of an automatic milking system

The aim of this experiment was to assess strategies to reduce milking time in a pasture-based automatic milking system (AMS). Milking time is an important factor in automatic milking because any reductions in box time can facilitate more milkings per day and hence higher production levels per AMS. This study evaluated 2 end-of-milking criteria treatments (teatcup removal at 30% and 50% of average milk flowrate at the quarter-level), 2 milking system vacuum treatments (static and dynamic, where the milking system vacuum could change during the peak milk flowrate period), and the interaction of these treatment effects on milking time in a Lely Astronaut A4 AMS (Maassluis, the Netherlands). The experiment was carried out at the research facility at Teagasc Moorepark, Cork, Ireland, and used 77 spring-calved cows, which were managed on a grass-based system. Cows were 179 DIM, with an average parity of 3. No significant differences in milk flowrate, milk yield, box time, milking time, or milking interval were found between treatments in this study on cows milked in an AMS on a pasture-based system. Average and peak milk flowrates of 2.15 kg/min and 3.48 kg/min, respectively, were observed during the experiment. Small increases in maximum milk flowrate were detected (+0.09 kg/min) due to the effect of increasing the system vacuum during the peak milk flow period. These small increases in maximum milk flowrate were not sufficient to deliver a significant reduction in milking time or box time. Furthermore, increasing the removal setting from 30% of the average milk flowrate to 50% of the average milk flowrate was not an effective means of reducing box time, because the resultant increase in removal flowrate of 0.12 kg/min was not enough to deliver practical or statistically significant decreases in milking time or box time. Hence, to make significant reductions in milking time, where cows have an average milk flow of 2 kg/min and yield per milking of 10 kg, end-of-milking criteria above 50% of average milk flowrate at the quarter level would be required.     

Comparative evaluation of atmospheric and vacuum microwave‐assisted extraction of bioactive compounds from fresh and dried Centella asiatica L. leaves

Microwave‐assisted extraction (MAE) involves extraction under higher‐temperature and oxygen‐rich environment, which may cause degradation of bioactive compounds being extracted. Reducing the extraction temperature by reducing the system pressure is thus of interest. Nevertheless, information is lacking on the kinetics of vacuum microwave‐assisted extraction (VMAE) at various pressures. Detailed temperature evolution of a material–solvent mixture during VMAE is also not available. This study investigated the extraction kinetics of triterpene saponins and phenolics from both fresh and dried Centella leaves during MAE and VMAE at various pressures. In the case of fresh leaves, the maximum contents of triterpene saponins were reached when VMAE was performed at 60 kPa, whereas the maximum total phenolics content (TPC) was achieved when the extraction was performed at atmospheric condition. In the case of dried leaves, the maximum triterpene saponins contents as well as TPC were achieved when extraction was performed at atmospheric condition.     

Separation of ultimate and technical esparto grass fibres: comparison between extraction methods

Esparto grass fibres are used as cordage or paper pulp. Ultimate and technical fibres used in pulp or cords have specific characteristics. Technical fibres have higher mechanical properties. However, ultimate fibres have a higher cellulosic rate, hence higher absorbency and retention capacity. To produce ultimate fibres, we must look for an appropriate method of extraction. In this paper, a method of extraction that gives cellulosic fibres without any damage is investigated and a comparison with other methods is also made. The structure of esparto grass technical fibres is discontinuous, where cellulosic fibres are found in matrix which contains pectin, lignin and hemicelluloses. The ultimate fibres from esparto grass have a length between 0, 2 and 3 mm and a diameter between 6 and 22 µm. This shows that ultimate fibres are very short; however, they have very interesting features. The chosen extraction method has many specifications: protecting properties using a combined method which is accomplished in a short time and which takes the ecological impact into consideration. In this work different stages are followed to obtain cellulosic fibres. These fibres are then characterised through several analyses such as scanning electron microscopy, X‐ray diffraction, diameter and rate of lignin elimination.     

Evaluation of antioxidant capacity of some fruit and vegetable foods: efficiency of extraction of a sequence of solvents

All methods for assessing the total antioxidant capacity (TAC) of food samples are strongly affected by the solvents used during extraction. In recent years a sequential solvent extraction procedure utilising water and acetone has been widely used for TAC measurements of foods. To better understand the efficiency of this procedure in terms of the amount of extracted antioxidants and the subsequent measurement of TAC, two vegetables (onion and spinach) and two fruits (orange and tomato) were sequentially extracted with water, acetone and chloroform. Each extract fraction was analysed separately for its content of known antioxidant compounds by specific procedures and for its TAC by the Trolox equivalent antioxidant capacity assay. The results showed that the compounds in the water and acetone extracts were the main contributors to TAC. The chloroform extracts did not contribute to TAC, with the exception of the spinach extract, owing to the presence of low levels of carotenoids. In conclusion, the analysed extraction procedure was more effective for foods rich in water‐soluble antioxidants than for those rich in lipid‐soluble antioxidants. Copyright © 2006 Society of Chemical Industry     

Comparative evaluation of microwave‐assisted extraction and preheated solvent extraction of bioactive compounds from a plant material: a case study with cabbages

Preheated solvent extraction (PSE) was evaluated via the analysis of the extraction kinetics, microstructure of extracted samples and energy consumption as alternative to microwave‐assisted extraction (MAE). Cabbage outer leaves and ethanol were used as test material and extraction solvent, respectively. MAE was first optimised in terms of glucosinolates and phenolics yields; total antioxidant activity of the extracts was also assessed. MAE at a specific absorbed power of 0.37 W g^?1 for 9 min was selected as optimum condition to extract glucosinolates and phenolics, while PSE was optimised at 6 min of the extraction. The highest normalised total glucosinolates and phenolic contents as well as antioxidant activities of the extracts obtained via MAE were not significantly different from those obtained via PSE. Confocal laser scanning microscopy revealed no significant differences in cabbage cell damages rendered by MAE and PSE. PSE nevertheless exhibited slightly higher specific energy consumption than MAE.     

Invited review: Contemporary environmental issues: A review of the dairy industry's role in climate change and air quality and the potential of mitigation through improved production efficiency

Environmental concerns involving the dairy industry are shifting from an exclusive focus on water quality to encompass climate change and air quality issues. The dairy industry's climate change air emissions of concern are the greenhouse gases methane and nitrous oxide. With regard to air quality, the dairy industry's major emission contributions are particulate matter, volatile organic compounds, and ammonia. The emissions of these compounds from dairies can be variable because of a number of factors including weather conditions, animal type, management, and nutrition. To evaluate and compare emissions across the diverse operations that comprise the US dairy industry, emissions should be reported per unit of output (e.g., per kg of 3.5% fat-corrected milk). Accurately modeling emissions with models that can predict the complex bio-geochemical processes responsible for emissions is critical to assess current emissions inventories and develop mitigation strategies. Improving the dairy industry's production efficiency (e.g., improvements in management, nutrition, reproduction, and cow comfort) is an effective way to reduce emissions per unit of milk. With accurate process-based models, emissions reductions due to improved production efficiency could be reported per unit of milk and predicted on a farm-to-farm basis.     

Relation between the structure of matrices and their mechanical relaxation mechanisms during the glass transition of biomaterials: A review

It has been demonstrated that industrial polysaccharides (agarose, deacylated gellan and κ-carrageenan) form networks of reduced enthalpic content in the presence of high levels of non-crystallizing co-solute (e.g., glucose syrup) that exhibit time-temperature dependent behaviour of a typical rubberlike polymer. In contrast, amylose holds its structural characteristics unaltered and does not reach a state of molecular mixing with glucose syrup, with morphological features being those of a micro phase-separated mixture. Variation in phase morphology and density of intermolecular associations leads to entropic or enthalpic viscoelasticity in systems, and it was utilised to define distinct classes of food related biomaterials exhibiting an extensive glass transition region or absence of vitrification phenomena. The approach was extended to encompass the experimental parameters of a porous matrix and the application of hydrostatic pressure. In the former, work discusses discrepancies in the T_g - porosity relationship attributable to the different extent to which the two techniques of calorimetry and mechanical spectroscopy respond to degrees of molecular mobility. In the latter, it was shown that the time-temperature-pressure equivalence of synthetic amorphous polymers is not operational in the glass-like behaviour of high sugar systems in the presence of gelatin or gelling polysaccharides. The existing body of evidence allowed quantitative treatment of results based on the asymmetric distribution theory of molecular relaxation time that identifies the chemical fingerprint of the local motions operating at the vicinity of T_g. Furthermore, the diffusional mobility of a bioactive compound within a glassy matrix could be followed in relation to temperature induced changes in free volume using the time-temperature superposition principle.     

Energy issues in microwave food processing: A review of developments and the enabling potentials of solid-state power delivery

The enormous magnitude and variety of microwave applications in household, commercial and industrial food processing creates a strong motivation for improving the energy efficiency and hence, sustainability of the process. This review critically assesses key energy issues associated with microwave food processing, focusing on previous energy performance studies, energy performance metrics, standards and regulations. Factors affecting energy-efficiency are categorised into source, load and source-load matching factors. This highlights the need for highly-flexible and controllable power sources capable of receiving real-time feedback on load properties, and effecting rapid control actions to minimise reflections, heating non-uniformities and other imperfections that lead to energy losses. A case is made for the use of solid-state amplifiers as alternatives to conventional power sources, magnetrons. By a full-scale techno-economic analysis, including energy aspects, it is shown that the use of solid-state amplifiers as replacements to magnetrons is promising, not only from an energy and overall technical perspective, but also in terms of economics.