稻壳灰同时制备脱色剂和水玻璃的研究

基于稻壳灰(RHA)含有均匀分布的主要由SiO2组成的高含量矿物质的事实,研究了RHA综合利用的方法.RHA先经碱法处理后转化为水玻璃和脱硅RHA(DRHA),然后DRHA用硫酸活化制得应用于植物油精炼中的脱色剂纯RHA(PRHA).分别探讨了影响水玻璃模数和PRHA脱色能力的因素.结果表明,在2～3 mol/L范围内改变NaOH浓度或在2～3 h范围内改变溶煮时间,可获得2.3～3.6模数的水玻璃产品.高脱硅率有利于PRHA的多孔性形成.在NaOH溶液浓度2 mol/L和溶煮时间2 h条件下,RHA转化为模数3.3的水玻璃和DRHA,SiO2溶出率达到94.83%.活化DRHA制备PRHA的最佳工艺为硫酸质量分数5%、活化时间4 h、活化温度90℃.PRHA对中性大豆毛油的脱色能力是目前植物油工业中常用的活性凹凸棒石粘土的3倍.     

综合利用烟杆废料制取优质活性炭

研究了以烟杆废料为原料，在微波辐照和传统加热下氯化锌法制取活性炭的方法．经对比实验得出，用微波辐照９min即可完成传统工艺中预热、干燥、炭化和活化４个阶段，活性炭产品的亚甲基监脱色力为170mL/g，微波辐照工艺的加热时间仅为传统工艺的1/20；用传统加热方法，炭化温度680℃，炭化时间1h，活化温度800℃，活化时间2h，活性炭的亚甲基蓝脱色力为150mL/g。2种方法制得的活性炭的亚甲基蓝脱色力均超过国家标准一级产品的指标（120mL/g）。     

微波辐射处理竹节废料制备活性炭研究

研究了以竹节及其炭化料为原料，采用微波辐射氯化锌法和水蒸气法制备活性炭的可行性。探讨了微波功率、活化时间、活化剂浓度及水蒸气流量对活性炭性能的影响。得到了微波辐射竹节废料制备活性炭的最佳工艺条件：水蒸气法的最佳条件为微波功率700W、活化时间7min、水蒸气流量3．1mL／min。用此工艺条件制得的活性炭碘吸附值1012．2mg／g、亚甲基蓝脱色率165mL／g、得率52．3％。该工艺所需活化时间为传统方法的l／45左右，得率为传统方法的2倍左右。氯化锌法的最佳条件为微波功率350w、活化时间5min、氯化锌质量分数40％。用此工艺条件制得的活性炭碘吸附值l088．4mg／g、亚甲基蓝脱色率220mL／g、得率39．2％。该工艺所需活化时间为传统方法的l／36，产品活性炭亚甲基蓝脱色率为国家一级标准的1．83倍(GB／T 12496．10-1999)。     

磷酸活化法制备棉秆活性炭的研究

通过研究活化工艺条件对棉秆活性炭吸附性能的影响，探讨了磷酸活化棉秆原料制备活性炭的可行性。结果表明：磷酸活化棉秆原料能制备出糖液脱色用活性炭的优级品，其碘吸附值、亚甲基蓝以及焦糖脱色力分别达N920mg／g、200mL/g和130％。其最佳活化工艺务件为：磷酸浓度50％，浸渍比2．5：1，浸溃时间60min，活化温度500％，活化时间60min。其中浸渍比对棉秆活性炭的脱色能力影响最大。     

磁性固体酸催化剂的合成及其酯化催化活性的研究

研究了以磁性体为核、催化活性体为壳的固体酸催化剂制备过程的结构转化及其酯化催化活性变化.在ZrOCl2/FeCl2投料为10∶1(质量比),酸浓度为1 mol/L,浸泡时间2 h,400℃焙烧1 h的条件下,制得了具有优异的催化活性的纳米磁性催化剂ZrO2/SiO2-Fe3O4.采用IR、扫描电镜(SEM)和孔径分布等...     

磷酸活化法制备木质活性炭研究

在不同操作条件下制备得到各种活性炭，实验测定了相应的活性炭得率及活性炭的亚甲基蓝脱色力和苯酚吸附值。并分别研究了它们与活化实验的浸渍比、活化时间和活化温度之间的关系。实验结果表明，浸渍比是磷酸活化法制备活性炭的最重要的影响因素。综合考虑活性炭的得率和吸附性能受活化操作参数的影响规律，探讨了磷酸活化法生产木质活性炭的最优操作参数。在实验范围内，选择磷酸活化法生产木质活性炭的浸渍比100％～150％，活化温度500℃左右，活化时间60～90min比较适宜。在相对最优实验条件下制备所得到的活性炭的比表面积达到1536m^2／g，微孔孔容和中孔孔容分别为0．581和0.267cm^3／g。     

马尾松硫酸盐浆两段氧脱木质素最佳工艺条件的研究

研究了马尾松硫酸浆两段氧脱木质素的最佳工艺条件。结果表明，第一段氧脱木质素的条件为：氧压0．6MPa，温度100℃，时间80min,NaOH 量5％，MgSO4用量0．5％，浆浓10％；第二段氧脱木质素的条件为：氧压0．4MPa，温度90℃，时间60min，NaOH用量3％，MgSO4用量0．5％，浆浓10％。在此条件下，OIOⅡ木质素脱除率达到72．5％，粘度775．2cm^3/g,得率90．5％。经过氧脱木质素后浆的裂断长5．8km，耐破指数5．3kPa.m^2/g，撕裂指数12．7mN.m^2/g。     

碱浸提法制备稻壳多孔质炭试验

采用碱浸提法制备了稻壳多孔质炭,探讨了碱煮稻壳炭化物制备多孔质炭的可行性,以及稻壳的炭化温度、碱液浓度、碱煮时间和浸提次数等因素对多孔质炭的碘吸附值和亚甲基蓝吸附值等吸附性能的影响.结果表明:使用2 mol/L的氢氧化钠溶液溶对600℃下炭化得到的稻壳炭化物1次碱煮2 h后,能够制备出碘吸附值达600mg/g,亚甲基蓝吸附值为45.4 mL/g的多孔质炭.用碱液直接浸提稻壳炭化物制备多孔质炭的方法是可行的.     

餐厨废油壳聚糖脱酸初探

指出了游离脂肪酸含量过高会对餐厨废油后续碱性酯化处理产生不利影响，通过碱液对壳聚糖进行（活化）改性，并对不同活化条件下的壳聚糖吸附餐厨废油中游离脂肪酸的效果进行了评价。研究发现：壳聚糖在40℃，0．9mol／L NaO H －乙醇溶液中活化6h后，吸附效率得到极大提升，再与餐厨废油发生吸附，当吸附时间为6h ，吸附温度为65℃时，吸附量最大，为131．1mgKO H／g。     

漂白稳定剂的研究

对改性蛋白石用作纸浆H2O2漂白稳定剂的可能性进行了考察，结果表明，纸浆H2O2漂白过程中采用改性蛋白石替代Na2SiO3作稳定剂是可行的。在相同用量下，麦草浆和脱墨浆的白度均可提高3％(ISO)以上。与蛋白石相比，改性蛋白石对纸浆H2O2漂白的稳定效能显著增强。对于改性蛋白石作稳定剂的纸浆H2O2漂白，在一定范围内提高温度和延长时间对漂白有利。适宜的工艺条件为：浆浓10％，H2O23％，NaOH1．5％，改性蛋白石3％，时间60min，温度70℃以上。在此条件下漂白麦草浆，白度增值可达16％(ISO)以上。此外，改性蛋白石用作纸浆H2O2漂白稳定剂时，添加少量MgSO4对漂白有利，添加0．05％MgSO。可提高纸浆白度约1％(ISO)。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。