微囊化薰衣草香型环保胶合板的研制

采用原位聚合成法制备的薰衣草香精微胶囊,按照普通胶合板生产工艺制备环保香型胶合板。研究了热压温度、热压时间及施香量等因子对环保香型胶合板表面胶合强度的影响,并进行了SEM电镜观测和GC-MS成分检测。结果表明:施香量5%(含水率10%左右的单板质量百分比),热压压力1.0 MPa,热压温度105℃,热压时间2.5 min条件下制得的环保香型胶合板,其表面胶合强度符合《人造板及饰面人造板理化性能》(GB/T 17657—1999)中规定的要求;薰衣草香精微胶囊能够存留于胶合板材中并缓释香味。     

三种植物精油对茶小绿叶蝉的作用及效果评价

指出了茶小绿叶蝉是危害茶叶的一种重要害虫,为此,选取3种植物精油,试验了它们对茶小绿叶蝉的作用及效果。结果表明:茶园使用适宜浓度的薰衣草、罗勒、迷迭香三种植物精油,能起到引诱茶小绿叶蝉的作用,且引诱效果罗勒精油最好,薰衣草精油其次,迷迭香精油最后。为茶小绿叶蝉无公害化防治及开发精油作为环保型行为调节剂提供理论依据。     

打造一座薰衣草花园

薰衣草的分类真薰衣草——最芳香的薰衣草所有提炼精油的薰衣草都是来自于这个类别,又分成三种:英国狭叶薰衣草:最为常见,原产地在南欧,花期6～7月。这是相对早花的品种,花色有蓝紫、淡粉和白色,非常耐寒,一般可耐-25℃。     

废旧车体竹胶板回收与再利用研究

对原料粒径、热压工艺及施胶量等影响再生刨花板的物理力学因素进行了探讨,总结了利用废旧竹胶板制备再生刨花板的实用工艺条件:原料粒径16~20目;热压温度140℃;热压时间10min;热压压力10MPa;施胶量15%。     

制板工艺因子对硅酸钠/酚醛树脂玉米秸秆刨花板性能的影响

采用硅酸钠/酚醛树脂胶制备玉米秸秆刨花板,考察工艺因子对试板物理力学性能的影响。结果表明:随着施胶量增加、热压温度升高、热压时间延长,试板吸水厚度率逐渐减小,静曲强度、弹性模量和内结合强度呈先增大后减小的趋势。按照优化工艺:施胶量17%、热压温度180℃,热压时间20s/mm,制备试板的吸水厚度膨胀率和力学性能均满足GB/T4897-2015《刨花板》中干燥状态下使用的家具型刨花板的(P2型)的要求。     

制板工艺因子对硅酸钠/酚醛树脂玉米秸秆刨花板性能的影响

采用硅酸钠/酚醛树脂胶制备玉米秸秆刨花板,考察工艺因子对试板物理力学性能的影响。结果表明:随着施胶量增加、热压温度升高、热压时间延长,试板吸水厚度率逐渐减小,静曲强度、弹性模量和内结合强度呈先增大后减小的趋势。按照优化工艺:施胶量17%、热压温度180℃,热压时间20 s/mm,制备试板的吸水厚度膨胀率和力学性能均满足GB/T 4897-2015《刨花板》中干燥状态下使用的家具型刨花板的(P2型)的要求。     

迷迭香抗氧化剂和精油综合提取技术研究(Ⅰ)——两步提取法

极性溶剂和非极性溶剂的两步提取法是迷迭香抗氧化剂和精油综合提取的有效方法,操作简单,容易实施。迷迭香抗氧化剂和精油两步综合提取的合理条件为:粉碎的迷迭香叶子,极性溶剂95%乙醇,90℃提取3~4 h,提取物再经非极性溶剂60~90℃石油醚提取。迷迭香精油的提取得率为1.50%,其成分分析显示为西班牙型;迷迭香抗氧化剂的提取得率为16.08%,活性炭脱色精制得率为85.00%,迷迭香抗氧化剂主要含有鼠尾草酸、鼠尾草酚和迷迭香酸等活性成分,它们的平均含量分别为17.78%、6.23%和3.37%。     

快速固化水泥刨花板的工艺试验

以速生杉木加工剩余物为主要原料、Na2SiO3为快速固化添加剂制备水泥刨花板,研究了冷、热压两种压板方式、Na2SiO3添加量、热压温度、热压时间、水灰比、灰木比、水泥种类和刨花形态等因素对水泥刨花板主要性能的影响.结果表明,热压法可适用于水泥刨花板制造,最佳工艺条件为:Na2SiO3添加量10%、热压温度95℃、热压时间12 min、水灰比0.6、灰木比2.6,制备的水泥刨花板的静曲强度达到10 MPa;采用MgCl2后处理能显著改善板的性能.     

喷雾干燥法制备皱皮木瓜籽油微胶囊及其性能研究

在单因素试验的基础上,利用正交试验探讨了皱皮木瓜籽油微胶囊制备的较佳工艺,结果表明:均质压力30 MPa,进风温度190℃,进料速率16 m L/min的条件下制备得到的微胶囊产品为淡黄色粉末,包埋率达83.59%,水分2.51%,密度0.625g/cm~3,吸水性9.191%,粒径39.440μm。对微胶囊产品的SEM电镜结果显示:微胶囊产品呈球形,表面完整光滑,微胶囊结构致密。在贮藏稳定性试验中,皱皮木瓜籽油微胶囊的稳定性优于未包埋的皱皮木瓜籽油,喷雾干燥法制备的微胶囊产品性能优异,大大延长了皱皮木瓜籽油的货架期。     

油茶籽油微胶囊凝聚法工艺技术的研究

以阿拉伯胶和明胶为壁材的凝聚法生产茶油微胶囊的工艺过程及条件如下5%阿拉伯胶和5%明胶与一定量油茶籽油在60℃下乳化1min,在pH4.4下凝聚0.5h,10℃下固化1h,经离心和真空干燥即可.该法制备的微胶囊,有较高的含油率和包埋率.其粒径与凝聚时的搅拌速度密切相关,但其水溶性较差.     

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.     

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.     

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。