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均匀设计法优化桦木醇超声波辅助提取工艺 总被引：1，自引：1，他引：0
以95%(体积分数,下同)的乙醇为溶剂,利用均匀设计法优化了超声波辅助提取白桦树皮中桦木醇的工艺,考察了各因素对桦木醇提取率的影响,并以高效液相色谱法测定了萃取物中桦木醇的含量。结果表明,在超声波功率400 W、提取时间70 min、提取温度70℃、液固比40∶1(mL∶g)的条件下,超声波辅助提取桦木醇提取率可达到83.43%±1.89%,纯度71.20%±0.74%。与传统回流提取法相比,超声波辅助提取法提取时间短、提取率高,具有一定的应用前景。用5%的碳酸钠水溶液对原料进行预处理,可减少酸性杂质对桦木醇提取的干扰。 相似文献
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四氢呋喃-苯混合溶剂法分离纯化桦木醇 总被引：1，自引：0，他引：1
本研究从白桦树皮中提取了桦木醇。采用混合溶剂法对提取的桦木醇进行了分离纯化，运用紫外分光光度法（UV）对纯化效果进行了比较分析；利用傅立叶红外光谱（FT-IR）对纯化样品进行了结构表征；利用高效液相色谱（HPLC）对纯化样品进行了定量测定。结果表明：从白桦树皮中提取桦木醇粗品的得率为34．52％；混合溶剂四氢呋喃-苯是纯化桦木醇的优良试剂，其体积比为1：2，桦木醇与混合溶剂比为1：30（g：mL），纯化桦木醇得率为31．19％。纯度为94．53％。纯化后桦木醇的熔点为248．9～251．3℃，与文献值一致，FT-IR谱图与标准品基本一致。与以往的分离纯化方法相比，四氢呋喃-苯混合溶剂法是一种简便、高效的分离纯化桦木醇的方法。 相似文献
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本研究从白桦树皮中提取了桦木醇.采用混合溶剂法对提取的桦木醇进行了分离纯化,运用紫外分光光度法(UV)对纯化效果进行了比较分析;利用傅立叶红外光谱(FT-IR)对纯化样品进行了结构表征;利用高效液相色谱(HPLC)对纯化样品进行了定量测定.结果表明从白桦树皮中提取桦木醇粗品的得率为34.52%;混合溶剂四氢呋喃-苯是纯化桦木醇的优良试剂,其体积比为12,桦木醇与混合溶剂比为130(gmL),纯化桦木醇得率为31.19%,纯度为94.53%.纯化后桦木醇的熔点为248.9～251.3℃,与文献值一致,FT-IR谱图与标准品基本一致.与以往的分离纯化方法相比,四氢呋喃-苯混合溶剂法是一种简便、高效的分离纯化桦木醇的方法. 相似文献
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白桦树皮中桦木醇超临界二氧化碳萃取的研究(英文) 总被引：4，自引：0，他引：4
桦木醇,一种药用五环三萜成分,大量存在于白桦(Betulaplatyphlly)树皮中。白桦树皮于2000年9月采集自黑龙江省塔源林场。超临界流体萃取技术(SFE)是一种新型分离技术,广泛用于药物和天然产物生产。本文研究了利用超临界CO2萃取技术从白桦皮中提取桦木醇的工艺条件,系统分析了携带剂用量、萃取压力和萃取温度等参数对桦木醇提取率的影响。结果表明,最佳的萃取条件为:每克桦树皮粉所用携带剂用量为1.5mL,萃取压力为20Mpa,萃取温度为55C,CO2流量为10kg/h,分离压力和分离温度分别为5.5Mpa和50C。图4参6。 相似文献
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均匀设计法优化桦木醇的超临界二氧化碳萃取工艺 总被引：1，自引：5，他引：1
利用均匀设计法优化了超临界CO2萃取(SCDE)桦树皮中桦木醇的工艺.采用均匀设计法考察了萃取温度、萃取压力、萃取时间对桦木醇收率的影响,并用高效液相色谱法测定了萃取物中桦木醇的含量.试验结果表明,在萃取温度 32 ℃、萃取压力 8 MPa、萃取时间 1 h、CO2流量为 20 kg/h 的条件下,SCDE的桦木醇得率为 16.96%,萃取物中桦木醇含量达到 74.88%.与其他提取方法相比,SCDE法尽管得率略低,但选择性好且无环境污染,具有一定的应用前景. 相似文献
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以兴安落叶松(Larix gmelinii Rupr．)木材的加工剩余物为原料．以水为溶剂，微波辅助提取阿拉伯半乳聚糖。通过对影响提取率的主要因素微波作用时间、做波功率、料液比和木粉粒度等进行正交试验．分析得出微波辅助提取阿拉伯半乳聚糖的较佳工艺参数为10．0g兴安落叶松木粉。微波功率210W。微波作用时间35min。料液质量比1：35．木粉粒度0．2～0．3mm时．阿拉伯半乳聚糖提取率17．47％。比传统水浴浸提法高1．6％，时间仅为原来的1/10。用红外和紫外光谱分析两种方法所得产物的化学结构相同。微波辅助提取的粗糖中杂质含量比传统水浴法低。实验结果表明．对于兴安落叶松木材中阿拉伯半乳聚糖的提取．微波辅助提取优于传统水浴浸提法。 相似文献
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《林业工程学报》2016,(6)
原花色素的提取通常采取用传统外加热方式的溶剂浸渍法,存在提取时间长、提取效率低等缺点,而微波辅助提取技术具有加热效率高、提取时间短和提取率高等优点,成为传统提取技术的一种替代方式。笔者以兴安落叶松和日本落叶松树皮为研究对象,对比研究了微波辅助提取法和常规水浴浸渍法在不同提取时间下对原花色素提取得率的影响,并利用紫外光谱仪和红外光谱仪对树皮提取物的结构进行了表征。结果表明,和常规浸渍法相比,利用微波辅助提取法可显著缩短提取时间,提高原花色素的提取得率,并且不会引起原花色素结构的破坏。兴安落叶松和日本落叶松树皮中原花色素的微波辅助提取适宜工艺条件为:微波功率200 W,提取时间10 min,温度60℃,溶剂为50%乙醇,溶剂和树皮的体积与质量比(mL∶g)为10∶1。在此条件下,兴安落叶松和日本落叶松树皮中原花色素的提取得率分别为239%和278%。两者树皮中的原花色素均以原花青素结构为主,仅含有少量原翠雀素。相同条件下,兴安落叶松树皮比日本落叶松树皮的原花色素提取得率稍低。微波辅助提取法适用于落叶松树皮中原花色素的提取,是一种快速、有效和安全的方法。 相似文献
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微波辅助提取柚皮精油的研究 总被引：7，自引：0，他引：7
进行了微波辅助提取柚皮精油的实验。结果表明,石油醚是微波辅助提取柚皮精油的最佳溶剂,液料质量比、物料含水率、粒度、微波功率等因素对微波辅助提取柚皮精油有较大影响。通过实验得到了柚皮精油提取的最佳工艺条件：物料粒度60目,物料含水率7．4％,总液料质量比14：1,微波功率300w,提取两次,每次微波辐射时间3min。提取液进行真空浓缩至不再有溶剂蒸出,得精油粗产品。往精油粗产品中加入乙醇溶解,放入～15℃冰箱中冷冻48h,离心分离去除树脂状物质,过滤,滤液进行真空浓缩后,即得精油,产率约2．09％,精油纯度99．0％。与传统的直接加热提取法相比,微波辅助提取法所用时间仅为直接加热提取法的1／20。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
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. 相似文献
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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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
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. 相似文献
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Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):118-130
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. 相似文献
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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。 相似文献
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Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
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. 相似文献
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《Wood material science & engineering》2013,8(2):76-84
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. 相似文献