Development and characterization of carbon-honeycomb monoliths from kenaf natural fibers: A preliminary study

A series of carbon-honeycomb monoliths from kenaf natural fibers (KNF) have been prepared and characterized. Firstly, KNF were physically mixed with polyvinyl acetate (PVA) as a binder and next the mixture was extruded through a die to form disc type monoliths. After the extrusion, the monoliths were dried, carbonized and, finally, physically activated with synthetic air at different temperatures (350-550 °C). The carbon-honeycomb monoliths were characterized by N₂ adsorption at −196 °C, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The experimental results indicate that the method proposed in this work was suitable for the synthesis of solid carbon monoliths with the presence of large meso- and macropores like long parallel and straight canals extended through their structure. MIP data and SEM images illustrate an evident and progressive aperture of the blocked parallel channels with an increase of the activation temperature.     

Effect of chitosan addition on the surface properties of kenaf (Hibiscus cannabinus) paper

The present paper studies the effect of chitosan, cationic starch and polyvinyl alcohol (PVA) as sizing agents to enhance surface properties of kenaf paper. The polymers were incorporated into the sheets by spray application. The results clearly showed that the addition of chitosan to a sheet formed from beaten fibers had excellent improvement in surface properties, compared to the effect of other additives. Sizing quality of cationic starch fairly matched with the sizing quality of chitosan, however, it was able to reduce the water absorption potential of paper more than chitosan at a same concentration. In most other properties, particularly the most important property for printing papers, surface smoothness, chitosan-sized papers are superior to the paper sized with cationic starch or PVA.     

淹水红麻生长发育及营养吸收规律的研究

本文探讨了淹水条件下红麻生长发育及营养吸收特点．结果表明淹水影响红麻根系的发育和生活力，养分的吸收与运输受阻而富集于麻株茎部，从而导致红麻叶片大量脱落，麻株生长停滞，光合强度降低，干物质积累量减少，茎杆木质素含量增加，纤维素合量减少。播种早的麻株耐淹能力明显大于播种迟的麻株。     

Characterization of kenaf phloem fibers in relation to stem growth

Microscopic study on phloem fibers in kenaf stem was carried out to examine the developmental process of phloem fiber and localization of noncellulosic polysaccharides in the cell walls. Histochemical observation showed that layered phloem fiber bundles developed external to the vascular cambium as stems grew after planting, and the number of layered bundles was higher in the bottom region of the stem regardless of growth stage. Based on immunocytochemical observations, cells making up the phloem fiber bundles had thick secondary cell walls containing mixed-linkage, (1 → 3, 1 → 4)-β-d-glucan as a component of hemicellulose. Other polysaccharides present in cell walls, namely xyloglucan, rhamnogalacturonan, and methyl-esterified homogalacturonan, were localized only, in the primary cell walls and/or in the junction between contiguous cells. In addition, mechanical evaluation on isolated kenaf fibers showed that the fiber strength varied by stem maturity and region: both higher tensile strength and initial Young's modulus were recorded in fibers obtained from the middle region of stems harvested 4-6 months after planting.     

红麻杂种一代及其亲本的遗传组成与配合力分析

以13份红麻品种按NCⅡ（NorthCaralina）6×7交配设计组配42个杂种F1代与其亲本为材料,研究了红麻杂种一代及亲本材料9个主要经济性状的遗传构成及配合力,结果表明：除干皮精洗率外,其它8个性状组合间差异均达显著或极显著水平;遗传变异系数、遗传力、遗传进度均以单株子皮重、单株纤维重等产量性状较高,其余性状相对较低;南选、ID40、84K114－2等亲本一般配合力较好;84210×南选,ID40×917等组合具有高的特殊配合力,表现为强优势组合。     

Improving the use of kenaf for kraft pulping by using mixtures of bast and core fibers

Kenaf (Hibiscus cannabinus L.) is a herbaceous annual plant amenable to use as a papermaking raw material. Kraft and soda pulping of kenaf have so far been done exclusively on the bark fraction (about 34–38% of the stem) or whole stem of the plant. Using kenaf bark exploits the higher quality of its bast fibers but reduces the typically high crop yields of this plant. In any case, core kraft pulp has acceptable properties some of which (e.g. tensile index, burst index) can even surpass those of bark pulp. Pulp made from both fractions has been found to exhibit better bonding properties than bark pulp. However, too high a proportion of core fibers can result in difficult drainage, a low tear strength or poor air permeability. These problems restrict the proportion of core that can be mixed with bast fibers, hinders separation of the two fractions and raises operational costs.The primary purpose of this study was to examine the influence of the core–bark ratio on the properties of mixed kenaf pulp. We used unrefined core pulp and refined bark pulp. Based on the results for kraft sacks, obtaining kenaf paper from both fractions has some advantages. Because Gurley air porosity changed dramatically with the proportion of core pulp used, it was used to determine the maximum amount of core fibers to be added to bast fibers. A proportion of up to 34% was found to have no adverse effect on air permeability. Such a proportion allowed paper strength to be preserved with an acceptable tear index (19.8 mN m²/g) and excellent tensile index (72 N m/g). Also, energy consumption was reduced if only the bark fraction was refined. The proposed strategy thus provides increased fiber yields of kenaf per hectare per year and valorizes the core fraction.     

Evaluation of the fineness of degummed bast fibers

Fiber fineness characteristics are important for yarn production and quality. In this paper, degummed bast fibers such as hemp, flax and ramie have been examined with the Optical Fiber Diameter Analyzer (OFDA100 and OFDA2000) systems for fiber fineness, in comparison with the conventional image analysis and the Wira airflow tester. The correlation between the results from these measurements was analysed. The results indicate that there is a significant linear co-relation between the fiber fineness measurement results obtained from those different systems. In addition, the mean fiber width and its coefficient of variation obtained from the OFDA100 system are smaller than those obtained from the OFDA2000 system, due to the difference in sample preparation methods. The OFDA2000 system can also measure the fiber fineness profile along the bast fiber plants, which can be useful for plant breeding.     

基于磁性固定化酶的α-亚麻酸植物甾醇酯合成工艺研究

采用固载有Candida rugosa的磁性固定化酶为生物催化剂,并将其用于α-亚麻酸植物甾醇酯的酶促合成。通过响应面分析优化实验条件,得到最佳工艺参数为：固定化酶用量为25.2mg/mL,甾醇底物浓度为146.5μmol/mL,异辛烷为溶剂,55℃反应5h,得到的植物甾醇的酯化率为92.61%。该固定化脂肪酶经过简单的溶剂清洗可以重复使用10次以上,仍能保持71.8%的催化活性。     

Chemical composition of lipophilic extractives from jute (Corchorus capsularis) fibers used for manufacturing of high-quality paper pulps

The chemical composition of the lipophilic extractives from jute (Corchorus capsularis) fibers, which are used for high-quality paper pulp manufacturing, was thoroughly studied. The extractives content was low (0.4%), and its composition was studied by gas chromatography–mass spectrometry. For a better characterization of the different homologous series and compounds present in minor amounts, the extract was also fractionated by solid-phase extraction. The most predominant lipophilic compounds present in jute fibers were high molecular weight ester waxes (24% of total extract), followed by free fatty acids (17%), free fatty alcohols (17%) and α-hydroxyfatty acids (14%). Additionally, significant amounts of alkanes (6%), ω-hydroxyfatty acids (6%), sterols (6%), steroid and triterpenoid ketones (3%) and steryl glycosides (1%) were also identified, together with minor amounts of mono- and diglycerides.     

酶法制备大豆多肽的研究

本文研究了以Alcalase碱性蛋白酶和风味蛋白酶水解大豆蛋白制备大豆肽的工艺。确定了酶水解的最佳温度、底物浓度、酶与底物浓度比,得到了Alcalase碱性蛋白酶和风味蛋白酶水解大豆分离蛋白的最佳水解工艺。     

Application of analytic hierarchy process for the selection of cotton fibers

In many engineering applications, the final decision is based on the evaluation of a number of alternatives in terms of a number of criteria. This problem may become very intricate when the selection criteria are expressed in terms of different units or the pertinent data are difficult to be quantified. The Analytic Hierarchy Process (AHP) is an effective way in dealing with such kind of complicated problems. Cotton fiber is selected or graded, in the spinning industries, based on several quality criteria. However, the existing selection or grading method based on Fiber quality Index (FqI) is rather crude and ambiguous. This paper presents a novel approach of cotton fiber selection using the AHP methodology of Multi Criteria Decision Making.     

Magnetic Resonance Imaging for Rapid Screening for the Nephrotoxic and Hepatotoxic Effects of Microcystins

In vivo visualization of kidney and liver damage by Magnetic Resonance Imaging (MRI) may offer an advantage when there is a need for a simple, non-invasive and rapid method for screening of the effects of potential nephrotoxic and hepatotoxic substances in chronic experiments. Here, we used MRI for monitoring chronic intoxication with microcystins (MCs) in rat. Male adult Wistar rats were treated every other day for eight months, either with MC-LR (10 μg/kg i.p.) or MC-YR (10 μg/kg i.p.). Control groups were treated with vehicle solutions. T₁-weighted MR-images were acquired before and at the end of the eight months experimental period. Kidney injury induced by the MCs presented with the increased intensity of T₁-weighted MR-signal of the kidneys and liver as compared to these organs from the control animals treated for eight months, either with the vehicle solution or with saline. The intensification of the T1-weighted MR-signal correlated with the increased volume density of heavily injured tubuli (R² = 0.77), with heavily damaged glomeruli (R² = 0.84) and with volume density of connective tissue (R² = 0.72). The changes in the MR signal intensity probably reflect the presence of an abundant proteinaceous material within the dilated nephrons and proliferation of the connective tissue. T₁-weighted MRI-is a valuable method for the in vivo screening of kidney and liver damage in rat models of intoxication with hepatotoxic and nephrotoxic agents, such as microcystins.     

Effect of processing method on the quality of cowpea (Vigna unguiculata) flour for akara preparation

An indigenous food mixture containing rice flour, milk coprecipitate, sprouted green gram paste and tomato pulp (2: 1: 1: 1 w/w) was developed and called a RCGT food mixture. It was autoclaved (1.5 kg/cm², 15min, 121 °C), cooled and fermented with 2% liquid culture (containing 10⁶ cells/ml broth). Two types of fermentations were carried out i.e. one step single culture fermentation [L. casei or L. plantarum (37 °C, 24 hr.)] and sequential culture fermentation [S. boulardii (25 °C, 24 hr.) +L. casei (37 °C, 24 hr.)]; [S. boulardii (25 °C, 24 hr.) + L. plantarum (37 °C, 24 hr.)]. All fermentations drastically reduced the contents of phytic acid, polyphenols and trypsin inhibitor activity while significantly improving the in vitro digestibilities of starch and protein. Sequential culture fermentations brought about further changes compared to one step single culture fermentation.     

A simple and rapid method for the detection of potato spindle tuber viroid (PSTVd) by RT-PCR

Summary A test procedure for PSTVd is described based on immobilisation of plant sap on filter paper, by dotting or tissue printing followed by RT-PCR. Tests were carried out using primarily and secondarily infected potato plants, primarily infected in vitro plants, and potato tubers. Print PCR was shown to be suitable for testing large samples of potato plants whereas dot PCR is recommended for in vitro plantlets and tuber tissue. Bulking one infected plant to 4 or 9 healthy plants gave reliable results with secondarily infected potato plants, but sometimes the test failed to detect PSTVd in primarily infected in vitro plants. Dotted and printed paper squares could be stored at 4°C for at least 2 weeks in Triton X-100 solution or under dry conditions. Storing at room temperature can lead to unreliable results.     

Low temperature suspension polymerization of methyl methacrylate for the preparation of high molecular weight poly(methyl methacrylate)/silver nanocomposite microspheres

In order to prepare high molecular weight poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres, methyl methacrylate was suspension-polymerized in the presence of silver nanoparticles at low temperature with 2,2′-azobis(2,4-dimethylvaleronitrile) as an initiator. The rate of conversion was increased by increasing the initiator concentration. When silver nanoparticles were added, the rate of polymerization decreased slightly. High monomer conversion (about 85 %) was obtained in spite of low polymerization temperature of 30°C. Under controlled conditions, PMMA/silver microspheres with various number-average degrees of polymerization (6,000–37,000) were prepared. Morphology studies revealed that except for normal suspension microspheres with a smooth surface, a golf ball-like appearance of the microspheres was observed, due to the migration and aggregation of the hydrophilic silver nanoparticles at the sublayer beneath the microsphere’s surface.     

结合海南橡胶龙江分公司割胶生产实践，从常规割胶、新制度割胶、阴阳刀割胶和气刺割胶等几方面来阐述不同割胶制度的割面规划及其要点与注意事项，以期对目前天然橡胶生产，尤其是民营胶园割胶生产提供理论指导。

结合海南橡胶龙江分公司割胶生产实践,从常规割胶、新制度割胶、阴阳刀割胶和气刺割胶等几方面来阐述不同割胶制度的割面规划及其要点与注意事项,以期对目前天然橡胶生产,尤其是民营胶园割胶生产提供理论指导。