全细胞生物催化制备生物柴油研究——全细胞生物催化剂催化豆油甲酯化反应

研究了全细胞生物催化剂催化大豆油甲酯化反应制备生物柴油的反应条件.结果表明,水是适宜的反应溶剂,且含水量占大豆油质量5%～20%时,全细胞催化剂有很高的催化活性.在甲醇分批添加(每12h加入1批),催化剂用量4%,甲醇与大豆油物质的量之比(醇油比)5∶1时,甲酯得率最高可达94%.全细胞生物催化剂在反应4次后甲酯得率仍可保持在82%,显示出良好的重复催化性能.     

促溶剂法制备光皮树油生物柴油研究

以光皮树油和甲醇为原料制备生物柴油,以丁酮作促溶剂,KOH做催化剂,考察反应时间、温度、催化剂、甲醇与油脂摩尔比对光皮树油转化为生物柴油得率的影响。得到光皮树油制备生物柴油的工艺条件:醇油摩尔比为6,温度65℃,催化剂为油脂质量的0.8%,反应时间为8 min,精制生物柴油得率为96%。     

全细胞生物催化制备生物柴油研究——固定化细胞的制备及其催化性能

以硅藻土、聚氨酯树脂、氧化铝和海藻酸钠4种载体固定化米根霉细胞,探讨它们催化大豆油甲酯化反应生产生物柴油的能力.结果表明聚氨酯树脂为适宜的固定载体,在80mL液体发酵培养基中,加入聚氨酯树脂0.6g时所制备得到的固定化细胞性能最佳,此时固定上细胞干质量为0.5560g,培养液酶活为17.4U/mL.将此固定化细胞用于催化大豆油甲酯化反应,在m(甲醇)∶m(大豆油)为5∶1甲醇分批加入(每12h加入1批)的情况下,甲酯得率可达94%.     

油茶籽残饼油制备生物柴油研究及工艺优化

研究了油茶籽残饼油制备生物柴油碱催化酯交换反应动力学过程,探索了反应动力学因素醇油物质的量比、催化剂用量、反应温度和反应时间对生物柴油得率的影响.正交试验结果表明,油茶籽残饼油酯交换反应的理想条件为:反应温度70℃,醇油物质的量比为6:1,催化剂用量为油质量的0.6%,反应时间90 min;此条件下生物柴油得率为94.43%.经权威机构检测,所制得生物柴油主要性能指标完全符合国家标准GB/T 20828-2007,具有广阔的应用前景.     

乌桕梓油酸碱催化法制备生物柴油的研究

以乌桕梓油为原料,采用酸碱催化法制备生物柴油,探讨温度、醇油比、催化剂含量等因素,在碱催化酯交换反应过程中对生物柴油转化率的影响。结果表明,随着温度、醇油比、催化剂含量的升高,乌桕梓油的转化率呈上升的趋势;在温度60℃,醇油比6∶1,KOH 1%的条件下,生物柴油的转化率可达98.84%,基本性质符合生物柴油的国家标准和0#柴油的国家标准。表明,乌桕籽可以作为制备生物柴油的一种良好原料。     

生物酶法制备生物柴油研究综述

就生物酶法制备生物柴油的研究现状进行了扼要概括,探讨了固定化脂肪酶法、液体酶法和全细胞催化法制备生物柴油的最新工艺进展。     

N~+注入诱变黑曲霉选育单宁酶生产菌株

以黑曲霉为出发菌株,经多次N+注入诱变,得到突变高产单宁酶菌株黑曲霉ANO2。该突变菌株其产单宁酶酶活为670.2 U/mL,较出发菌株的单宁酶酶活442.3 U/mL提高51.4%以上,突变菌株经传10代培养,产酶特性稳定,是一株比较理想的单宁酶生产菌株。     

磁性固体催化剂催化制备生物柴油的研究

乌桕是我国特有的四大木本油料树种之一,本研究用磁性固体催化剂催化乌桕梓油制备生物柴油。通过正交试验得出最佳条件下的酯化率为95.59%;气相色谱检测表明:由乌桕梓油制备的生物柴油的主要成分是C16∶0、C18∶0、C18∶1、C18∶2和C18∶3的脂肪酸甲酯。     

生物油脂精炼制备柴油新方法的研究进展

综述了以甘油三酯为原料的生物质柴油精练新方法。重点介绍了脂肪酶催化、催化热裂解、催化加氢3种途径的特点和现状:其中脂肪酶催化是制备生物柴油环境友好的生产工艺,是目前最有产业化前景的制备技术;而催化热裂解、催化加氢目前尚在研究阶段,这两种制备方法所得到的燃料油性能较好,与化石燃料油组成及燃料性质接近。同时指出了3种制备方法存在的问题,并展望了3种生物质柴油制备方法各自的发展方向。     

响应面法优化钙基固体碱KF/CaO催化沉香籽油制备生物柴油

采用固体碱KF/Ca O催化沉香籽油进行酯交换反应制备生物柴油(脂肪酸甲酯),通过扫描电镜、X射线衍射和傅里叶红外的表征发现KF/Ca O呈多层片状结构,具有较大的比表面积(107±0.5)m~2/g,催化活性主要成分为KCa F3,红外谱图验证了Ca—O—F晶格的存在。单因素试验对影响催化酯交换反应的各因素进行优化,得出较佳范围为:反应时间100 min、催化剂用量2.0%、醇油摩尔比8∶1、反应温度79℃。单因素试验基础上采用Design-Expert软件Box-Behnken模块进行响应面试验条件优化,探讨了催化剂用量(A)、反应温度(B)、醇油摩尔比(C)、反应时间(D)4个因素及各因素间交互作用对转化率的影响,结果表明各因素一次项对转化率都呈高度显著水平,最佳条件为:反应时间107.2 min、催化剂用量2.02%、醇油摩尔比8.36∶1、反应温度79.14℃,所制备的生物柴油能够满足国标要求。     

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.     

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。     

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.