酶法提取越桔果渣花色苷酶解条件的研究

对酶法提取越桔果渣花色苷的酶解条件进行研究。考察了酶解温度、酶解液初始pH值、酶解时间、酶用量和固液比对越桔花色苷的影响;确定了酶解的最优条件为50℃、酶解液初始pH值为4.5、酶解时间为3h、酶用量为5.0mg/g果渣粉、固液比为1∶4;对酶法提取越桔果渣花色苷与传统乙醇浸提法进行比较。结果表明在一定条件下,酶法提取工艺比传统乙醇浸提越桔果渣花色苷色价提高了30%。     

水酶法协同超声波辅助提取八角莲总黄酮工艺条件

以八角莲为原料,采用水酶法协同超声波辅助提取法对八角莲总黄酮的提取工艺进行优化,以纤维素酶用量、酶解温度、酶解时间及pH等为影响因素,通过单因素和正交实验,研究了提取八角莲总黄酮的最佳工艺条件。结果表明:纤维素酶0.015 g,提取温度50℃,酶解时间150 min,酶解pH7.0时八角莲总黄酮的提取率最高,达7.398%。     

超声波辅助提取蓝莓果渣中花色苷的工艺研究

目的:确定超声波辅助提取蓝莓果渣中花色苷的最佳工艺。方法:采用正交试验确定超声波辅助提取蓝莓花色苷的最佳工艺条件。结果:超声波辅助提取蓝莓果渣中花色苷的最佳工艺条件为提取剂为酸性乙醇,固液比1∶60(g/mL),超声波功率350W,萃取时间40min,提取温度75℃。在此条件下,确定的蓝莓果渣花色苷含量3.122mg/g。结论:超声波辅助提取技术对充分利用蓝莓资源获取高附加值的花色苷是可行的。     

纤维素酶解预处理法提取杜仲胶的工艺研究

以蒽酮比色法测定的酶解液中的总糖含量和酶解杜仲胶的提取率为考察指标,优化纤维素酶解预处理杜仲粕壳的工艺条件。结果表明,纤维素酶预处理杜仲粕壳的最佳工艺条件:温度50℃,pH值3.8,酶的用量为0.30 g,料液比为1∶15(g∶mL),酶解2次,每次3 h。经最佳酶解工艺条件预处理后的杜仲粕壳,第一次提取酶解物中杜仲胶得率达到57.7%,是非酶解物中的1.3倍。采用薄层层析法检测,结果表明经酶解预处理后所提取的胶与非酶解而提取的胶成分基本相同。     

杜仲叶残渣酶预处理提取杜仲胶生产工艺

为了优化杜仲胶提取工艺,以酶解液中的总糖含量和酶解杜仲胶的提取率为试验考察指标,来确定纤维素复合酶预处理杜仲叶残渣的生产工艺条件。试验结果表明:纤维素复合酶预处理杜仲叶残渣的最佳工艺条件为pH值5.5,温度50℃,酶用量为1.6 mg/g,料液比为1∶15(g∶mL),酶解4 h。与非酶解原料相比,杜仲叶残渣经酶解预处理后胶提取率是未经酶解的1.49倍。表明纤维素复合酶可用于杜仲叶残渣提取杜仲胶的酶解预处理过程。     

红薯膳食纤维提取工艺优化试验

以红薯为原料,对影响红薯可溶性膳食纤维提取的因素(料液比、溶液pH值、温度、纤维素酶添加量和酶解时间5个因素)进行了单因素试验,然后在此基础上进行了正交试验,得到了纤维素酶制备红薯可溶性膳食纤维的最佳条件:料液比1∶12、温度55℃,pH值为6,纤维素酶的添加量20U/g,酶解时间2h。以此条件提取的红薯水溶性膳食纤维的含量高达20.91%,能显著提高红薯水溶性膳食纤维的提取率。     

响应面法优化纤维素酶辅助提取大果沙棘果渣总黄酮工艺研究

采用纤维素酶辅助法对沙棘果加工废弃物沙棘果渣中的总黄酮物质进行提取。在单因素试验的基础上,采用响应面分析法对酶辅助法提取沙棘果渣黄酮类物质提取条件进行优化。建立并分析了酶用量、液固比、提取温度和pH值4因子与总黄酮得率关系的数学模型。沙棘果渣黄酮类物质提取的最佳工艺条件为:纤维素酶用量78.9 IU/g,液固比值25.9,温度59.1℃,pH值3.9。试验证明,在此条件下,总黄酮得率为(8.48±0.16)mg/g(n=3),与模型预测值8.57 mg/g基本一致。响应面模型回归方程与实际情况拟合良好,能较好地预测大果沙棘果渣中总黄酮的提取得率。     

酶法提取红松球果挥发油工艺研究

以红松球果脱种剩余物为原料,经粉碎、酶解、水蒸气蒸馏提取挥发油,通过单因素试验和正交试验,确定最佳提取工艺条件为:选用纤维素酶和果胶酶的混合酶(质量比1∶1),料液比1∶8,酶添加量1.7%,酶解pH为4.5,酶解温度45℃,酶解时间3.5 h,在此工艺条件下,挥发油得率为1.775%。     

酶法提取荆芥总黄酮的研究

研究了酶法提取荆芥总黄酮的工艺。通过单因素实验,探讨了粉碎度、料液比、酶解温度、酶解pH值、酶解时间、酶的用量对总黄酮提取率的影响,筛选出影响提取的主要因素,再通过正交实验,优化得到酶法提取荆芥总黄酮的最佳工艺条件。实验结果表明,各因素对提取率的影响顺序依次为粉碎度〉酶解时间〉酶的用量〉料液比。通过正交实验优选得到的最佳提取工艺为：药材粉碎度为50目,料液比为1：16,酶的用量为0．8％,酶解温度为40℃,酶解pH值为5,酶解时间为20min后,煎煮1．5h。该法操作简单、提取率高,可用于荆芥总黄酮的提取。     

超临界CO_2萃取除脂后再经纤维素酶辅助提取落叶松树皮原花青素

将超临界流体萃取与纤维素酶法相结合,对落叶松树皮中原花青素的提取工艺进行了研究。首先,采用超临界CO2从落叶松树皮中提取脂溶性成分,采用萃取压力35 MPa、温度50℃,萃取130 min后,树脂平均得率为2.16%,然后将萃余物通过纤维素酶辅助提取原花青素,通过单因素和正交试验确定了原花青素提取的最佳工艺条件为:3 g脱脂树皮粉以缓冲液为溶剂,原料粒度为150~178μm,纤维酶加入量为原料质量的0.6%,液料比14∶1(mL∶g),酶解pH值5,酶解温度40℃,酶解时间2 h后,原花青素的得率可以达到7.36%。通过扫描电子显微镜观察和傅立叶变换红外光谱分析表明,提取树脂后的树皮纤维结构有不同程度的破坏,从而促使胞内物质溶出,提高了得率,所获得的落叶松树皮原花青素分子中主要存在原花青定型结构单元,没有使有效成分的结构发生改变。     

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.     

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.     

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。