产业用纺织品的织造技术

在织造产业用纺织品时 ,尤其是用片梭和喷气织机织造时需要些什么样的特殊设计和附加的要求呢 ?作者在织物和其他相关的方面提供了一些详细的分析。产业用纺织品可以用传统的或非传统的织机成功地织造 ,如用片梭、喷水、喷气、剑杆织机以及圆机等。虽然织造的基础如 :开口、引纬、打纬保持不变 ,但一些附加的特殊设计却是需要的 ,它与传统的服装纺织品的织造有区别。1　片梭织机单根长丝用作纬纱时 ,采用带边盘的圆柱型纬纱筒子供纱。其升程在 1 60ｍｍ～ 1 2 5ｍｍ之间 ,边盘直径在 2 0 0ｍｍ～ 2 5 0ｍｍ之间。所以纬纱不能直接引纬。为了…     

Monitoring of black tea fermentation process using electronic nose

Black tea fermentation is essentially an oxidation process. After the plucked tea leaves are treated by series of processes called withering (removal of moisture by air flow), pre-conditioning and CTC (essentially maceration and cutting of leaves), the leaves are subjected to the process of fermentation by exposing them to air by laying the cut tea leaves on floor, trough or moving conveyor under controlled temperature, humidity and air-flow conditions. During this process, the leaves change colour from green to coppery brown and the grassy smell gets transformed to floral smell. It is critical that the leaves be allowed to ferment only up to the desired limit and both under and over fermentation result in deteriorated quality of black tea. Out of the two detectable parameters (colour and smell), smell is very important since a strong, very specific fragrance emanates from the leaves once leaves are optimally fermented. A new electronic nose-based approach for monitoring of tea aroma during fermentation is proposed. Two methods namely the 2-Norm method (2NM) and the Mahalanobis distance method (MDM) were tested and the results were correlated with the results of colorimetric tests and human expert evaluation.     

A study on the adsorption mechanism of mercury on Aspergillus versicolor biomass

The adsorption behavior of mercury on Aspergillus versicolor biomass (AVB) has been investigated in aqueous solution to understand the physicochemical process involved and to explore the potentiality of AVB in pollution control management. This biomass has been successfully used for reducing the mercury concentration level in the effluent of chloralkali and battery industries to a permissible limit. The results establish that 75.6 mg of mercury is adsorbed per gram of biomass. The adsorption process is found to be a function of pH of the solution, with the optimum range being pH 5.0-6.0. The process obeys the Langmuir-Freundlich isotherm model. Scanning electron microscopic analysis demonstrates a conspicuous surface morphology change of the mercury-adsorbed biomass. A nearly uniform distribution of metal ions on the mycelial surface excepting a few aggregation points is revealed by X-ray elemental mapping profiles. The results of zeta potential measurement, Fourier transform infrared (FTIR) spectroscopy, and blocking of the functional groups by chemical modification reflect the binding of mercury on the biomass occurs through electrostatic and complexation reactions. The accumulation of mercury on the cell wall associated with negligible diffusion and or transportation into cytoplasm finds support from the results of adsorption kinetics and transmission electron micrographs. Mercury adsorption on biomass also leads to elongation of cells and cytoplasmic aggregation of spheroplast/protoplasts, indicating that the cell wall acts as a permeation barrier against this toxic metal.     

Chemical and physical pretreatments of fruits and vegetables: Effects on drying characteristics and quality attributes – a comprehensive review

Pretreatment is widely used before drying of agro-products to inactivate enzymes, enhance drying process and improve quality of dried products. In current work, the influence of various pretreatments on drying characteristics and quality attributes of fruits and vegetables is summarized. They include chemical solution (hyperosmotic, alkali, sulfite and acid, etc.) and gas (sulfur dioxide, carbon dioxide and ozone) treatments, thermal blanching (hot water, steam, super heated steam impingement, ohmic and microwave heating, etc), and non-thermal process (ultrasound, freezing, pulsed electric field, and high hydrostatic pressure, etc). Chemical pretreatments effectively enhance drying kinetics, meanwhile, it causes soluble nutrients losing, trigger food safety issues by chemical residual. Conventional hot water blanching has significant effect on inactivating various undesirable enzymatic reactions, destroying microorganisms, and softening the texture, as well as facilitating drying rate. However, it induces undesirable quality of products, e.g., loss of texture, soluble nutrients, pigment and aroma. Novel blanching treatments, such as high-humidity hot air impingement blanching, microwave and ohmic heat blanching can reduce the nutrition loss and are more efficient. Non-thermal technologies can be a better alternative to thermal blanching to overcome these drawbacks, and more fundamental researches are needed for better design and scale up.     

Microwave freeze drying of sea cucumber (Stichopus japonicus)

Freeze drying (FD) yields the best quality of dried sea cucumber but at the cost of long drying time and also the overall cost. Air drying (AD) gives an unacceptably poor quality product. To achieve faster drying along with a high quality product a microwave freeze drying (MFD) technique was developed to dry sea cucumbers. The relationship between corona discharge and microwave power at various pressures and initial moisture content conditions was studied to avoid the possibility of corona discharge during MFD. According to the drying characteristics of MFD, a control strategy for the MFD process was also developed. MFD reduced the drying time by about half of conventional FD process and provided a similar good product quality.     

Optimization and surface modification of silk fabric using DBD air plasma for improving wicking properties

It is necessary to study the suitable effect of plasma parameters, such as exposure time and applied voltage on the wicking properties of silk fabrics. Wicking property of silk fabric has been improved by using air dielectric barrier discharge plasma treatment. The plasma treatment has been utilized to modify the surface properties of silk fabrics. Untreated and plasma-treated fabrics have been characterized by contact angle Goniometer, wicking test, Wet-out time, scanning electron microscope, Attenuated Total Reflection Fourier Transforms Infrared spectrometer (ATR-FTIR) and dye uptake test. The ATR-FTIR characterization shows that the hydroxyl functional group has been increased after plasma treatment of silk fabric. The experimental results of wicking rate and Wet-out time of the plasma-treated silk fabrics have shown significant improvement in hydrophilic properties that could be confirmed by contact angle measurement which is close to 0°. The tensile strength of untreated and plasma-treated fabrics has been measured to confirm the enhanced surface property.     

Lactic acid bacteria isolated from ethnic preserved meat products of the Western Himalayas

We used culture- and molecular-biology-based methods to investigate the diversity of lactic acid bacteria (LAB) in the ethnic chevon (goat) meat products chartayshya, jamma and arjia of the Western Himalayas. In six chartayshya, six jamma and four arjia samples, LAB were the predominant microbial component involved in the fermentation of these samples, and the total LAB population in arjia (7.8 ± 0.1 log cfu g⁻¹; mean ± SD) was significantly higher (P < 0.05) than in chartayshya (6.9 ± 0.1 log cfu g⁻¹) and jamma (7.5 ± 0.1 log cfu g⁻¹). We identified 53 LAB samples by 16S rRNA and phenylalanyl-tRNA synthase (pheS) genes sequencing. The LAB isolates were identified as Enterococcus durans, Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Leuconostoc citreum, Leuconostoc mesenteroides, Pediococcus pentosaceus, and Weissella cibaria. These results revealed that there is a high level of diversity of LAB in the Himalayan ethnic preserved meat products.     

Hardness and Fracture Toughness of SiC-Particle-Reinforced MoSi2 Composites

The indentation technique has been used to evaluate the hardness and fracture toughness of SiC-reinforced MoSi₂ composites made by hot-pressing. It is seen that the toughness increases with increasing indentation crack length (under increasing load) and a probable mechanism responsible for this behavior is described. It is also observed that there is an optimum volume fraction of SiC particles for which the maximum fracture toughness of the composite can be achieved.     

DRYING OF CLAY AND NONCLAY MEDIA : HEAT AND MASS TRANSFER AND QUALITY ASPECTS

The researches on drying of clay and nonclay media are briefly reviewed and the role of drying in the manufacturing process is summarized. The drying process must be carefully controlled to maintain the desired product configuration. Inefficient completion of drying and poor operation of the dryer influence directly the product quality. The importance of R&D on the heat and moisture transfer phenomena, shrinkage mechanisms, deformation behavior, strain-stress relations and the internal pressure in the media during drying is stressed. Suggestions are given for further improvement of the drying process and improved design of the molding and casting processes for higher product quality