Fiber charge characteristics of pulp suspension containing aluminum sulfate

Fiber charge characteristics of pulp suspensions containing aluminum sulfate were investigated with relation to adsorption behavior of aluminum components on the pulp fibers by streaming potential measurement using a particle charge detector, X-ray photoelectron spectroscopy, and X-ray fluorescence analysis. When aluminum sulfate was added to a pulp suspension prepared using deionized water, a streaming potential of the suspension went from negative to slightly negative according to the adsorption of aluminum components on the pulp fibers. Subsequent addition of a dilute NaOH solution to the suspension drastically cationized the fibers in the pH range of around 5 by predominant and homogeneous adsorption of cationic aluminum complexes on the fiber surfaces. However, the aluminum flocs that formed heterogeneously on the fiber surfaces at higher pH by further alkali addition made nearly no contribution to cationization of the fibers, although the abundant aluminum components were retained in the pulp sheets. Therefore, only aluminum cations adsorbed uniformly on the fiber surfaces perform well to control the charge properties of the pulp fibers at the wet end; and the preferential aluminum adsorption behavior on the fiber surfaces, by utilizing the required amounts of hydroxyl ions, probably accounts for the effective cationization of the fibers under acidic to neutral papermaking conditions.This research was presented in part at the presymposium of the International Symposium on Wood and Pulping Chemistry, Seoul, June 1999; at the International Symposium on Environmentally Friendly and Emerging Technologies for a Sustainable Pulp and Paper Industry, Taipei, April 2000; and at the 2000 annual meeting of the Society of Fiber Science and Technology, Japan, Kyoto, June 2000     

Influence of neutral inorganic chlorides on primary and secondary char formation from cellulose

The influence of various alkali and alkaline earth metal chlorides (LiCl, NaCl, KCl, MgCl₂, and CaCl₂) on primary and secondary char formation from cellulose was studied at 400°C. Secondary char was formed through carbonization of the volatile products. All chlorides increased the primary char yield while decreasing the secondary char formation, and this situation was promoted in the order of alkaline earth Mg, Ca, alkali Li > alkali Na, K. Levoglucosan yield also decreased along with the secondary char yield. These results indicate that the reduced formation of volatile levoglucosan was related to the decreasing yield of secondary char. A model experiment at 250°C revealed that these chlorides, especially the two alkaline earth metals, had catalytic action on the polymerization of levoglucosan, which serves to reduce the formation of volatile levoglucosan.     

Decomposition behavior of cellulose in supercritical water, subcritical water, and their combined treatments

A comparative study on decomposition of cellulose between supercritical water (400°C, 40MPa) and subcritical water (280°C, 40MPa) treatments was made to elucidate the difference in their decomposition behavior. Consequently, the supercritical water treatment was found to be more suitable for obtaining high yields of hydrolyzed products. However, cellulose was found to be more liable to fragment under supercritical water treatment, resulting in a decrease in the yield of hydrolyzed products. On the contrary, cellulose was found to be liable to more dehydration in the subcritical water treatment. Based on these results, we have proposed the combined process of short supercritical water treatment followed by subcritical water treatment so as to inhibit fragmentation. Consequently, this combined treatment was able to effectively control the reaction condition, and to increase the yield of hydrolyzed products.     

Pyrolysis behavior of levoglucosan as an intermediate in cellulose pyrolysis: polymerization into polysaccharide as a key reaction to carbonized product formation

Pyrolysis behavior of levoglucosan (1,6-anhydro--d-glucopyranose), the major anhydromonosaccharide formed during cellulose pyrolysis, was studied at 250°–400°C under nitrogen. The pyrolysis products were found to change stepwise: levoglucosan MeOH-soluble fraction (lower-molecular-weight products and oligosaccharides) water-soluble fraction (polysaccharides) insoluble fraction (carbonized products). From the present experimental results, a pathway of cellulose pyrolysis via anhydromonosaccharide is proposed including polymerization to polysaccharides (a reversible reaction) as a key reaction to carbonized product formation.Part of this study was presented at the XIXth International Carbohydrate Symposium, San Diego, August 1998; and the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

Effect of nitrogen and carbon sources on lignin and cellulose degradation by Armillaria ostoyae

Lignin has been hypothesized to be the primary mechanism of resistance to fungal pathogens in plant tissue. Degradation of lignin and cellulose by Armillaria ostoyae cultured for six weeks in Melin-Norkrans medium containing various nitrogen and carbon sources was measured radiometrically. No consistent pattern of lignin or cellulose degradation was found, regardless of A. ostoyae isolate, nitrogen source and concentration, or carbon concentration. More lignin was degraded as the concentration of glucose and fructose increased but not when the concentration of sucrose increased.     

Influence of the degree of substitution and pretreatments on the surface structure of cellulose nitrate fibres

Summary Cellulose nitrate fibres of three different degrees of substitution (DS) were prepared by heterogeneous reaction. The fibre surfaces were observed in the scanning electron microscope. Apart from the DS the influence of pretreatments such as prenitration and boiling of the fibres prior to nitration was studied. The results reveal an interaction between the cell wall layers and the esterification and swelling capacity of the nitration medium. In all cases the DS was determined by the composition of the nitration medium. A pretreatment influenced the fibre surfaces after nitration. The peculiar role of the primary wall during esterification is emphasized.Supported by the Federal Ministry for Research and Technology (BMFT)     

Effect of thinning and fertilizer on the cellulose crystallite width of Eucalyptus globulus

An analysis of cellulose crystallite width, microfibril angle and wood density after the time of thinning (at 8 years) in straight vertical trees was undertaken in a 13-year-old E. globulus trial designed to assess the effect of thinning on tension wood formation. The most important effect was on cellulose crystallite width, which increased with thinning intensity and this was mitigated where fertilizer was applied at the time of thinning. Given the relationship between high crystallite width and tension wood occurrence the results demonstrate that heavy thinning of E. globulus at this age can contribute to tension wood formation. However, tension wood production may be significantly reduced where fertilizer is applied. This is possibly because increased diameter growth as a response to fertilizer application stabilises the stems and this is the mechanism by which trees cope with internal stresses that are generated from wind in destabilsed stands following thinning. In contrast, trees that respond poorly to thinning produce tension wood.     

锈蚀诱导处理下竹钉和钢钉的抗剪性能

以钢钉、普通竹钉和压缩竹钉连接SPF(云杉-松木-冷杉类)规格材试件,用质量分数为5%的盐水对试件作锈蚀诱导处理,进行短梁剪切和抗剪试验,探讨锈蚀诱导处理对钉抗剪性能的影响。结果表明,竹钉和木材连接部位呈犬牙交错状,能有效约束木构件,维持其抗剪性能;锈蚀诱导处理对钉连接的水平剪切承载力和极限抗弯承载力的影响不显著,不同钉连接的水平剪切承载力和极限抗弯承载力无显著差异,水平剪切承载力范围为6.08~6.90 k N,极限抗弯承载力范围为6.19~7.01 k N;锈蚀诱导处理使钢钉剪切破坏提前,而对竹钉的极限荷载影响并不显著;锈蚀诱导处理使普通竹钉的极限荷载对应位移显著增大,而对钢钉和压缩竹钉影响不显著。     

Influence of carboxyl group on the acid hydrolysis of cellulose

Cellulose isolated from wood is more susceptible than cotton cellulose to homogeneous hydrolysis in phosphoric acid. The influence of carboxyl group introduction at the C6 position on the hydrolysis rate of cellulose in 82.5% phosphoric acid was studied as a model of the oxidation of cellulose during pulping. The rate constant of hydrolysis for dissolving pulp was larger than that of cotton cellulose at temperatures of 25°–35°C. Mercerized cotton cellulose was partially oxidized regioselectively at the C6 position by a free radical system using 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). The oxidized cellulose was obtained at a range of 1.7–12.7 mEq carboxyl content per 100 g of cellulose. The hydrolysis rate of the oxidized cellulose samples accelerated with increasing carboxyl content in the samples.Part of this work was presented at the 5th Annual Meeting of the Cellulose Society of Japan, Kyoto, July 1998     

天牛类昆虫交配行为研究进展

天牛是一类在我国危害严重且防治难度较大的林木蛀干害虫.虽然其种类众多,经济和生态价值大,但国内外较少有对天牛繁殖交配行为的总结报道.梳理国内外对天牛交配行为的研究,发现天牛交配行为可分为求偶、性冲动、交配前准备、交配四个阶段,每个阶段都不可缺少,且有其阶段特征性的行为.在交配后,一些雄性天牛会表现出配后保护行为.天牛交...     

石膏刨花板饰面性能的研究

本研究分别采用刨切薄木、三聚氰胺浸渍纸及PVC塑料薄膜对石膏刨花板进行了饰面装饰试验,并测定了饰面材料与基材的胶合强度。结果表明,石膏刨花板具有良好的饰面性能。     

Effect of temperature and compression on the mechanical behavior of steam-treated wood

The mechanical behavior of steamed spruce wood changes dramatically with compression along the grain, the change being much more moderate perpendicular to the grain. The stiffness decrement due to increased temperature is greatest in the tangential material direction. The stiffness decrement due to compression is greatest along the grain. Compression to 80% compressive strain at 131°C inverts the order of the material directions regarding stiffness, the stiffness being the least along the grain. Plastic strain due to compression is greater at higher temperatures. The compression-induced decrement of stiffness along the grain is greater at higher temperatures, but the off-axis decrement of stiffness is less at higher temperatures.     

Effect of thermomechanical densification on surface roughness of wood veneers

The effect of short-term thermomechanical densification of veneer on the surface roughness and surface anatomical changes in four wood species – alder (Alnus glutinosa Gaertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.) – was studied. Veneer sheets were densified at a temperature of 100, 150, or 200°C and at a pressure of 4, 8, or 12 MPa for 4 minutes. Seven roughness parameters such as R_a, R_z, R_q, R_p, R_v, R_sk, and R_ku were determined. Profile surface was recorded using a modified Carl Zeiss ME-10 profile gauging profilometer. Surface anatomical changes of veneer were examined using scanning electron microscopy. The results showed that densification temperature and pressure affect surface roughness of veneer. The surface became smoother, and roughness values decreased significantly (except for R_ku which increased slightly) with increasing temperature and pressure of densification. The effect of temperature on surface roughness changes is more pronounced compared with that of densification pressure. The lowest values of surface roughness were recorded for pine veneer samples followed by alder, birch, and beech samples. These results can be used to provide initial data for adhesive application processes in woodworking industry.     

宽带砂光机主要参数对其加工工件表面粗糙度的影响

以台湾CHIALUNG公司300型宽带砂光机为研究对象,在分析了其砂削工件表面粗糙度影响因素的基础上,以桦木、松木、柞木为加工对象进行实验,研究各主要参数对其加工工件表面精度的影响规律.     

Influence of host on behavior ofSclerotinia sclerotiorum

All these hosts became less susceptible as the plants matures. Ascospores were unable to infect linseed leaves in the absence of an exogenous nutrient base. Even though sucrose could be used as an exogenous nutrient to stimulate the ascospores to germinate, the ascospores subsequently failed to infect undamaged linseed leaves. Linseed flower petals were an effective nutrient base which stimulated ascospores to germinate as well as to infect undamaged linseed leaves. (Responsible: Editor: Sun Yueqi).     

STUDY ON MEASUREMENT OF WOOD SURFACEROUGHNESS BY COMPUTER VISION

The working processes,machining devices and tools,cutting amount,consumptionof materials,productivity and quality of products are directly affected wood surface roughness.This paper gives an extensive review of methods used previously to measure wood surfaceroughness,and concludes that computer vision is the most suitable.The preliminarystudy shows that computer vinon method has the advantages of a noncontact,three--dimensionalmeasurement,high speed and well correlates with stylus tracing method.The method can be usedin classification and in-time measurement of wood surface roughness after being improved.     

Predatory behavior of Tetrigus lewisi on Monochamus aiternatus

Pine wilt is a serious and fatal disease in pine forests. It is caused by the pine wood nematode, Bursaphelenchus xylophilus,transmitted by the Japanese saw beetle Monochamus alternatus. Control of this disease depends on reducing its vector population.The public is demanding environmentally friendly control methods and biological control has become increasingly seen as an important, safe and effective approach. Through our investigations both in the field and by breeding in our laboratory, a new predator of M.alternatus, Tetrigus lewisi (Coleoptera: Elateridae), was found for the first time in China. Given our continuous observations, we are assured that the predatory behavior of the elater can be separated into four parts, i.e., foraging and sensing, killing, eating and excretion. They always took several hours to eat the preys that have been killed momentarily. We finally found that most of the elaters preferably attacked in the stomach and abdomen of the larva of M. alternatus.     

Influence of coating properties on paper-to-paper friction of coated paper

Coated paper-to-coated paper friction properties were examined in relation to printing runnability difficulties like erroneous double feeding of paper sheets. Higher ratios of precipitated calcium carbonate (PCC) to clay in mixed pigment coatings resulted in higher static and kinetic coefficients of friction (COFs). Microroughness in the order of pigment particle size is considered to relate to COF, because cube-shaped particles of PCC resist sliding. Calendering decreased COF at larger amounts of PCC, but did not change COF of the sole clay formulation at all. Addition of ground calcium carbonate (GCC) decreased COF. The rate of decrease in kinetic COF with increasing number of sliding for the GCC-rich formulation was higher than that for the PCC-rich formulation, presumably because protruding parts, characteristic of the GCC-rich formulation, on the surface were selectively flattened. Addition of styrene-butadiene (SB)-latex up to 14pph decreased COF, but static COF had the highest value at 18pph. The antislip property (as a rubber) of SB-latex developed only in the static mode. Among lubricants formulated, the wax type decreased COF the most remarkably with more effect on kinetic COF than on static COF. Part of this report was presented at the 11th International Printing and Graphic Arts Conference, Bordeaux, France, October 2002     

地表积水状况对芦苇形态结构及生物量的影响

地表积水对芦苇形态结构及生长的影响研究结果表明：（1）地表积水深度对芦苇个体茎粗度、节间长度、节数均有显著影响。随着地表积水深度的增加芦苇平均茎粗度变大,节问变长,节数减少。（2）在不同积水状况下,芦苇地下茎形态变化明显,3种积水类型平均茎粗度排序为常年干旱〉季节性积水〉长期积水。季节性积水苇田的芦苇地下茎的节间长度较长,节数最多;常年干旱次之,但节数少;长期积水苇田的芦苇地下茎细、节间短、节数多。（3）土壤积水类型,芦苇地下茎与须根的比例差异很大。常年干旱苇田芦苇地下茎占地下部分总生物量的91．84％;季节性积水苇田芦苇地下茎占总量的54．95％;长期积水苇田的芦苇地下茎占总量的45．13％。（4）地表积水状况对芦苇个体生长有很大影响。表现为常年干旱苇田的芦苇个体粗大,密度过稀。季节性积水苇田的芦苇生物量最高,但密度较低。而长期积水苇田的芦苇粗度小,但密度最大。     

Prescribed burning effects on the hydrologic behavior of gullies in the South Carolina Piedmont

Gullies found in the Piedmont of South Carolina are legacies of past land use and erosion. Although the majority of these gullies are now under forest vegetation and perceived as geomorphologically stable, the question of gully contribution to nonpoint source pollution remains undetermined, especially when these gullies are subjected to prescribed burning or other forest disturbance. Six prescribed burned and two reference gullies draining mature pine stands grown on former cotton fields were instrumented at the Long Cane Ranger District, Sumter National Forest, South Carolina to characterize the hydrologic behavior of these gullies and to investigate response to prescribed burning. Flow in the gullies was observed for one year of pre-burn and one year of post-burn conditions. Hydrologic behavior of these eight gullies varied greatly in the pre-treatment period. During the study, 48 rainfall events exceeding 12.7 mm were recorded, but one reference gully never produced flow and three treatment gullies flowed during three events or less and only in the pre-burn period. Although significant storm events occurred throughout the year, all gully flow events occurred between December and March. Double-mass and graphical analysis of relative stormflow production of the reference and treatment gullies in the pre- and post-treatment periods did not indicate an effect of the controlled burn on flow behavior, but the post-burn year was characterized by drought. The observed inter-annual variation in gully behavior was large. Observations of local groundwater conditions with piezometers and electrical resistivity surveys indicated that gully flows were controlled by the presence of a flow-restricting layer below the gully bed.