Preparation of high surface area activated carbons from tobacco stems with K2CO3 activation using microwave radiation

In this paper, activated carbons with high surface area from carbonized tobacco stems with K₂CO₃ activation by microwave radiation were investigated. Effects of microwave radiation time and K₂CO₃/C ratio on the yield and adsorption capacities of activated carbons were evaluated. Experimental results indicated that the optimum conditions were as follow: microwave power 700 W; microwave radiation time 30 min; K₂CO₃/C ratio 1.5:1. Iodine number, amount of methylene blue adsorption and the yield of activated carbon prepared under optimum conditions were 1834 mg/g, 517.5 mg/g and 16.65%, respectively. Surface area, micropore volume and pore size distribution (PSD) of the carbons were determined by the BET, H-K and DFT methods. Results showed that activated carbons had a micropore content about 59.98% and a small number of mesopores and macropores; BET specific surface area and total pore volume were 2557 m²/g and 1.647 cm³/g, respectively.     

蚯蚓粪配比的泥炭基质特性及其栽培的小型西瓜幼苗生长状况

以蚯蚓粪按照不同体积比替代泥炭作为基质开展小型西瓜育苗试验,研究蚯蚓粪配比的泥炭基质特性及其栽培的小型西瓜幼苗生长状况。结果表明,随着蚯蚓粪添加比例的增加,基质的pH、电导率（Electric conductivity, EC）、干容重、湿容重总体呈逐渐上升趋势,最大持水量、总孔隙度、毛管孔隙度则呈逐渐下降趋势,当蚯蚓粪所占比例达到或超过50%可能给基质物理特性带来不利影响。添加了蚯蚓粪的基质,细菌和真菌数量明显下降,尤以细菌数量的降幅最大,微生物总量随之大幅降低。小型西瓜幼苗在S2基质（含10%蚯蚓粪）中的株高、茎粗、生物量、根长、根表面积均为最高,生长状况最好,综合评价得分最高,表明在泥炭基质中添加10%蚯蚓粪有利于提升小型西瓜育苗效果。相关性分析结果显示,小型西瓜幼苗的生长受基质物理特性的影响较大,其茎粗、根长及综合评价得分与基质干、湿容重呈极显著或显著负相关,与基质最大持水量、总孔隙度和毛管孔隙度呈极显著或显著正相关。     

Hydrophilic and flexible polyurethane foams using sodium alginate as polyol: Effects of PEG molecular weight and cross-linking agent content on water absorbency

Hydrophilic and flexible polyurethane foams were prepared using sodium alginate as a polyol, and characterized by optical microscopy, FT-IR spectroscopy, density measurements, volume swelling, and water absorbency. Optical microscopy revealed that the resulting cells were closed with round and elongated shapes. FT-IR confirmed that the urethane linkages were formed between the isocyanate and sodium-alginate. As an indirect measurement of porosity, the apparent density indicated an initial decrease followed by an increase with increasing glycerin content. The volume-swelling ratio was initially constant, followed by a gradual decrease with glycerin content. The volume swelling ratio increased with PEG molecular weight. The water absorbency initially increased, followed by a decrease with increasing glycerin content. The correlation-ships between water absorbency, density, and volume-swelling ratio indicated that the absorbency was predominantly influenced by density when the PEG molecular weight was low and was greatly affected by the volume-swelling ratio when the PEG molecular weight was relatively high.     

Influence of the draw ratio on the mechanical properties and electrical conductivity of nanofilled thermoplastic polyurethane fibers

Electrically conducting textile fibers were produced by wet-spinning under various volume fractions using thermoplastic polyurethane (TPU) as a polymer and carbon black (CB), Ag-powder, multi-walled carbon nanotubes (MWCNTs), which are widely used as electrically conducting nanofillers. After applying the fiber to the heat drawing process at different draw ratios, the filler volume fraction, linear density, breaking to strength, and electrical conductivity according to each draw ratio and volume fraction. In addition, scanning electron microscopy (SEM) images were taken. The breaking to strength of the TPU fiber containing the nanofillers increased with increasing draw ratio. At a draw ratio of 2.5, the breaking to strength of the TPU fiber increased by 105 % for neat-TPU, 88 % for CB, 86 % for Ag-powder, and 127 % for MWCNT compared to the undrawn fiber. The breaking to strength of the TPU fiber containing CB decreased gradually with increasing volume fraction, and in case of Ag-powder, it decreased sharply owing to its specific gravity. The electrical conductivity of the TPU fiber containing CB and Ag-powder decreased with increasing draw ratio, but the electrical conductivity of the TPU fiber containing MWCNT increased rapidly after the addition of 1.34 vol. % or over. The moment when the aggregation of MWCNT occurred and its breaking to strength started to decrease was determined to be the percolation threshold of the electrical conductivity. The heat drawing process of the fiber-form material containing the anisotropic electrical conductivity nanofillers make the percolation threshold of the electrical conductivity and the maximum breaking to strength appear at a lower volume fraction. This is effective in the development of a breaking to strength and electrical conductivity.     

Effects of carbonization temperatures on characteristics of porosity in coconut shell chars and activated carbons derived from carbonized coconut shell chars

A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, 800 and 1000 °C) on characteristics of porosity in carbonized coconut shell char and activated carbon derived from carbonized coconut shell char with different activation times (30, 60, 90 and 120 min) at activation temperature of 900 °C. The results showed that high temperature carbonized coconut shell char and activated carbon samples derived from high temperature carbonized coconut shell chars had higher BET surface area, total volume, micropore volume and yield as compared to those of low temperature carbonized coconut shell char and activated carbon derived from low temperature carbonized coconut shell char. The BET surface area, total volume and micropore volume of activated carbon prepared from char obtained at 1000 °C with activation time of 120 min were 1926 m²/g, 1.26 cm³/g and 0.931 cm³/g, respectively. From the results, it was concluded that we could produce high surface area activated carbons from coconut shells using physical activation (steam activation) by proper selections of carbonization temperature and activation time.     

菌渣在烟草育苗中的应用效果分析

本文以废弃菌渣为基础基质,配以草炭和蚯蚓粪等,探索适合烟草育苗的基质配方,并分析菌渣在烟草育苗中的应用效果。结果表明T4处理组（蚯蚓粪∶菌渣∶蛭石∶珍珠岩=1∶1∶1∶1）在株高、根系发育等表观生长指标和可溶性糖、根系活力等生理活性指标方面相较于市售基质处理组（草炭∶蛭石∶珍珠岩=2∶1∶1）均有明显的优势。通过SPSS软件对基质物理、化学性状和烟草生长生理指标进行多元线性回归分析,结果表明,基质较高的总孔隙度、有效铁含量和全钾含量能有利于烟草幼苗的生长,而较高的电导率、有机碳含量和全氮含量则不利于烟草幼苗的生长。菌渣具有高总孔隙度、高有效铁、适宜营养结构和低成本的优势,但也有高电导率、低容重和高有机碳的劣势,不宜单独作为基质,应用适当配方,可充分发挥菌渣的作用,是一种好的基质材料,具有广阔的基质化应用前景。     

微波辅助乙醇提取大豆异黄酮的研究

以乙醇作为萃取剂,采用微波法从大豆中提取异黄酮,分别考察了微波功率、乙醇的体积分数、料液比和微波辐射时间对异黄酮提取量的影响.结果表明:从大豆中提取异黄酮的最佳工艺条件:微波功率400 w、乙醇的体积分数50%、料液比1:4、微波辐射时间5 min.在最佳工艺条件下,异黄酮的提取量1.3205 mg.g-1.与传统溶剂...     

Electrical Resistivity of Plasma Treated Viscose and Cotton Fabrics with Incorporated Metal Ions

Cellulose fabrics (viscose and cotton) were treated with atmospheric pressure dielectric barrier discharge (DBD) in air. After DBD treatment, samples were characterized and volume electrical resistance was measured under different relative humidity conditions (φ=40-55 %). Results have shown that DBD treatment increases wettability and polar surface functional groups content, which consequently causes a decrease of volume electrical resistivity of cellulose fabrics in measured relative humidity range (φ=40-55 %). Metal ions (silver, copper, and zinc) were incorporated in untreated and plasma treated samples through sorption from aqueous solutions and incorporation of metal ions into plasma treated cellulose samples decreased electrical resistivity even further. Resistivity of cotton and viscose fabrics with incorporated metal ions followed the order Zn²⁺ > Cu²⁺ > Ag⁺. The most pronounced decrease, for entire order of a magnitude, was obtained by modification of cotton fabric with DBD and silver ions, where value of resistivity dropped from GΩ to a several dozens of MΩ.     

收获后烟秆不同处理方式对烟草病害发生的影响

为了探讨烤烟收获后烟秆不同处理方式对烟草病害的影响，采用多点单因素田间小区实验，研究了2种基本烟秆处理方式下烟田青枯病、黑胫病与病毒病的发生情况。结果表明：烟秆离田上岸处理比砍断还田处理的烟田青枯病、黑胫病与病毒病的始发期分别推迟14、35、23 d；盛发期发病率分别降低21.58%、17.02%、16.35%，病指降低8.89、7.95、6.80；定案调查期发病率分别降低32.15%、17.68%、22.10%，病指降低19.77、10.09、10.10；离田上岸处理烟田青枯病、黑胫病与病毒病发病增长率（定案期-盛发期）分别为1.33%、1.23%、0.19%，病指增长（定案期-盛发期）分别为0.39、0.55、0.20。试验表明，烟秆离田上岸处理可以推迟黑胫病的始发期，降低青枯病的发病率与病指，可以更好地减缓病毒病的扩散。     

The influence of water jet pressure settings on the structure and absorbency of spunlace nonwoven

Nowadays, the use of nonwovens as absorbent products is increasing. One of the most important methods for the nonwoven production is spunlace. This research evaluates the effect of spunlace nonwoven structures in wicking, water retention, water vapor permeability and porosity structural parameter of nonwoven. Carded webs from polyester fibers and viscous fibers of four different basis weights (35, 40, 45, and 50 g/m²) were hydroentangled using three different water jet pressures (50, 60, and 70 bar). To study the effect of these variables on the structure of nonwovens and absorbency related properties, sample’s characteristics such as thickness and mass density were measured. An electrical resistance technique was used to study the liquid penetration into nonwovens. The results showed that with increasing water jet pressure, mass density increased and other parameters like thickness, water retention, water vapor permeability and capillary pore size decreased. Also, it was observed with increasing basis weight, the sample thickness increased. On the other hand, with increasing weight, the amount of water retention, water vapor permeability and porosity structural parameter of nonwoven were reduced. The wicking characteristic of nonwovens using the least jet pressure and weight was the best of all the samples.     

密集烘烤过程中烟叶颜色、形态和水分变化及相互关系

以K326中部烟叶为材料,研究了密集烘烤过程中烟叶颜色参数、形态、水分变化特征及其关系.结果表明:密集烘烤过程中烟叶正面与背面颜色参数值变化趋势基本一致,且烘烤前期变化幅度较大,烘烤后期变化幅度较小,同时正面变化速度较背面快.主脉的颜色参数值变化较叶片变化滞后.烘烤开始烟叶厚度收缩率一直呈现较大变化,进入干筋期变化趋势减缓;其余各形态指标前期变化幅度较小,中期相对剧烈,后期又逐渐减缓.烘烤过程中叶片、主脉及整叶相对含水量呈现递减趋势,前期失水速度慢,中期失水速度快.密集烘烤过程中烟叶正面、背面和主脉的红度值与烟叶的收缩率指标、卷曲率指标和含水率指标呈显著或极显著相关;烟叶背面亮度值与收缩率指标和纵向卷曲率、烟叶正面亮度值与厚度收缩率、主脉黄度值与横向卷曲率和含水率指标呈显著或极显著相关.     

Usage of undersize bulgur flour in production of short-cut pasta-like couscous

Couscous is a traditional cereal product produced by rubbing durum semolina particles with water by hand, but can be produced by using pasta pressing technique. This study aimed to produce a short-cut pasta type couscous by substitution of semolina with undersize bulgur at 25, 50, 75 and 100%, by determining optimum parameters. Bulk density, cooking loss, volume and weight increases, protein and ash contents, color, sensory, texture and functional properties were determined. Couscous samples were prepared and dried using packed bed (60 and 80 °C) and microwave dryers (180 and 360 W) to determine optimum parameters. It was found that the quantity of bulgur flour was significantly (p ≤ 0.05) effective on the sensory attributes, bulk density, cooking loss, volume and weight increases, protein and ash contents in contrast to functional properties. Weight and volume increase values decreased with increasing quantity of bulgur flour. Couscous samples containing bulgur flour have higher protein than the control due to higher protein content of bulgur. According to texture profile, hardness of couscous containing bulgur flour was lower than the semolina control for each drying technique. Results revealed the fact that the production of pasta type couscous is possible using totally undersize bulgur instead of semolina.     

移栽株距对隆回烟叶产量和质量的影响

烤烟的移栽密度已成为影响烟叶产量和质量的重要因素。2012年度,以移栽株距为45 cm、行距110 cm和目前推广的移栽株距为50 cm、行距110 cm进行对比试验。试验结果表明,处理组的综合表现优于对照组：产值比对照提高5.15%,低次等烟降低了0.13%;烟株生长前期和中期,处理组的根密集层密度较对照组分别大3 cm和1 cm,在生长后期,处理的烟株较对照茎高高17 cm,茎围大4 cm。表明株距为45 cm、行距为110 cm的移栽密度适宜在邵阳隆回地区大面积推广。     

Microwave irradiation differentially affect the physicochemical properties of waxy and non-waxy hull-less barley starch

Waxy and non-waxy hull-less barley kernels and their isolated starches were irradiated under different microwave conditions (power 640, 720, and 800 W, time 60, 120 and 180 s). Changes in physicochemical properties were studied to investigate the effects of microwave irradiation (MWI) on in-kernel starches and isolated starches. For in-kernel starch, microwave reduced the ratio of 1047/1022 cm⁻¹ wavelengths, gelatinization enthalpy (ΔH_g) and relative crystallinity (RC), indicating that microwave of starch within the cells disrupted the crystalline regions. For isolated starch, microwave decreased the ratio of 1047/1022 cm⁻¹ wavelengths but increased ΔH_g of isolated starch, indicating that microwaving resulted in disruption of amorphous structure and an increase in the amount of remaining double helix structure. Moreover, viscosities of in-kernel starches decreased as microwave power and time increased, but this was not observed in isolated starches. Microwave treatment induced an enhancement of gelatinization temperature for non-waxy starches (NWS) but decreased in waxy starches (WS). Microwave had a greater effect for swelling power and solubility on in-kernel MWI-WS than MWI-WS, whereas the reverse results were found between in-kernel MWI-NWS and MWI-NWS. The results indicated that amylose plays a profound role in the properties of isolated and in-kernel starches during microwaving.     

Hemp-fiber based nonwoven composites: Effects of alkalization on sound absorption performance

The effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of alkalized three layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature, duration and concentration. The alkalized composite was a three-layered nonwoven sandwich structure consisting layers of Polypropylene/Hemp/Polypropylene. Alkalization treatment has been found to result in a loss of basis weight and a decrease in air flow resistivity. Among treatment factors, only temperature was found to be a statistically-significant factor on air flow resistivity. Higher-temperature alkalization leads to higher air flow resistivity compared to the lower-temperature treatment. Alkalization at higher temperature and higher concentrations gives better results in normalized sound absorption performance compared to lower-temperature and lower-concentration treatments, respectively.     

Starch Digestibility and Physicochemical and Cooking Properties of Irradiated Rice Grains

This study evaluated the starch digestibility, physicochemical properties and cooking characteristics of polished rice (varieties IRGA417 and IAC202) subjected to the doses of 0 (as the control), 1, 2 and 5 kGy of gamma radiation. The highest dose decreased the apparent amylose content, peak viscosity, water absorption and volume expansion. Irradiation increased the solid loss by 119% and 187% for IAC202 and IRGA417, respectively, when comparing the higher dose with the control. For IAC202, irradiation decreased the rapidly digestible starch and increased the slowly digestible starch (SDS) and resistant starch (RS). IRGA417 showed an elevation of SDS and a reduction in RS. And 1 kGy dose of gamma radiation generated the highest level of RS for both the two varieties and presented the smallest changes in other physicochemical and cooking properties.     

Effect of microwave irradiation on composition,structure and properties of rice (Oryza sativa L.) with different milling degrees

Effects of microwave irradiation on composition, structure, thermal and storage properties of rice with different milling degrees were investigated. Microwave irradiation partially inactivated the lipase and lipoxidase, damaged thiamine, and created puffed rice. In addition, the transition temperatures (T_o and T_P) of rice were shifted to higher temperatures, and the enthalpy of gelatinization decreased after irradiation. The effect was more obvious when the power of microwave was increased. Microstructure analysis showed that stress cracks and some “explosion” were created in rice kernels after microwave irradiation. Storage property analysis indicated that free fatty acid content of all rice samples increased gradually in the process of storage. Microwave irradiation reduced the release of free fatty acids during storage. The higher the power, the lesser the free fatty acids generated. The results suggested that microwave irradiation was potentially applicable for improving storage properties of brown and milled rice.     

Determination of the Mineral Fraction and Rheological Properties of Microwave Modified Starch from Canna Edulis

The goal of this study was to evaluate the effect of the physical modification by microwave irradiation on the mineral fraction and rheological properties of starch isolated from Canna edulis rhizomes. Phosphorus, sodium, potassium, magnesium, iron, calcium and zinc were evaluated using atomic absorption spectrophotometry. Rheological properties were determined using both the Brabender amylograph and Brookfield viscosimeter. Except for the calcium concentration, mineral contents decreased significantly (p < 0.05) after microwave treatment. The amylographic profile was also modified, showing increased pasting temperature range and breakdown index, whereas the viscosity peak, viscosity at holding (95°C) and cooling periods (50°C), setback and consistency decreased as compared to the native starch counterpart. Although viscosity decreased in the microwaved sample, presumably due to starch changes at molecular level, it retained the general pseudo plastic behavior of native starch. It is concluded that canna starch may be modified by microwave irradiation in order to change its functional properties. This information should be considered when using microwave irradiation for food processing. Furthermore, the altered functional attributes of canna modified starch could be advantageous in new product development.     

Preparation and characterization of porous carbon based nanocomposite for supercapacitor

Porous nanocomposites are prepared by electrospinning blended polyacrylonitrile, copper acetate and mutiwalled carbon nanotube in N, N-dimethylformamide. The electrospun nanofiber webs are oxidatively stabilized and then carbonized resulting in composite carbon nanofibers. The study reveals that composite nanofibers with relatively smooth surface morphology are successfully prepared. X-ray diffraction is used to confirm the presence of Cu in carbon nanofibers. The carbon nanofibers with CNTs have better thermal stability and higher electrical conductivity. The Brunauer-Emmett-Teller analysis reveals that C/Cu/CNTs nanocomposites with mesopores possess larger specific surface area and narrower pore size distribution than that of C/Cu nanofibers. The electrochemical properties are investigated by cyclic voltammetry and galvanostatic charge-discharge tests. The nanocomposite with 0.5 wt.% CNT loading exhibits an energy density of 2 Whkg^?1, power density of 1916 Wkg^?1, a specific capacitance of about 225 Fg^?1 at a current density of 2 Ag^?1 and its capacitance decreased to 78 % of its initial value after 3,000 cycles.     

Impact of shading and cutting on the demography and composition of Mimosa pudica L., a ligneous weed species of tropical grasslands

The aim of the study was to evaluate the potential impact of grazing on the control of Mimosa pudica, a ligneous weed species that invades grasslands in French Guiana. Three experiments were conducted in a glasshouse to test the potential impact of: (i) shading by testing different Photsynthetically Active Radiation (PAR) fluxes on seedlings and (ii) cutting of juveniles, at three stages of development, on their survival, flowering rate and nutritive value as measured by the mass:length ratio of stems and by branching processes. A significant mortality rate (0·20) was obtained only for seedlings at the cotyledon stage when the PAR flux was reduced proportionately by 0·83. Shading reduced both flowering rate and mass:length ratio of stems. For seedlings at the cotyledon stage, the flowering rate decreased from 0·85 for the control to zero for the low light treatment (0·13 of PAR flux of the control treatment). The mass:length ratio of stems of seedlings in the low light treatment was reduced to 0·20 of that of control seedlings, at the fifth‐leaf stage. Cutting treatment had no effect on mortality of juvenile plants whatever the size of the juvenile plant. The proportion of juvenile plants flowering was high for all cutting treatments. It is suggested that regular, but not continuous grazing, could maintain a dense sward to limit recruitment by seedling establishment and seed production, and maintain branched and juvenile plants with a high‐nutritive value at the seedling stage.