从栀子皮中提取果胶的研究

对栀子皮提取果胶的方法进行了研究,先用水提取水溶性果胶,再用酸水解法提取水不溶性果胶.用正交试验法优化了水不溶性果胶提取工艺.最佳工艺条件为:pH值1～1.5,温度 90 ℃,时间 120 min,水料比8.25∶1(mL∶g).水溶性果胶得率 13.2%,水不溶性果胶得率 14.1%,总得率 27.3%.本方法提取的果胶甲氧基含量为 4.93%,果胶含量为 82.4%.     

响应面法对狐臭柴鲜叶果胶提取条件的优化

筛选并优化狐臭柴鲜叶果胶提取条件,为狐臭柴鲜叶果胶资源的有效利用提供参考。以狐臭柴鲜叶为原料,柠檬酸为酸解质提取其鲜叶果胶,首先进行单因素实验,研究不同液料比、柠檬酸浓度、提取温度、提取时间对果胶提取率的影响。在单因素实验基础上,采用响应面法对果胶提取条件进行优化。响应面方程模型的P 0.000 1 0.01,其模拟效果较为合理(模型失拟项P=0.728 3 0.05)。最佳提取条件为液料比12:1(mL:g)、柠檬酸含量7.0%、提取温度85℃、提取时间2.0 h。在此优化条件下,果胶提取率为23.32%,与理论值(24.12%)具有较好的拟合。该方法提取的果胶呈鲜嫩淡黄色,其制作的神仙豆腐色泽翠绿、外观规则,为狐臭柴资源的产业化开发提供了有效途径。     

天仙果果胶提取条件及含量测定

以天仙果果实为原料采取盐酸溶液萃取、酒精沉析制取果胶;确定最佳提取工艺条件为提取温度87~90℃、pH 0.5~1.0、萃取时间2h、料液比1∶20。研究了亚硫酸氢钠对天仙果果胶得率的影响;用咔唑比色法对其含量进行了准确测定。     

柚皮果胶的盐析研究

采用盐析法从柚皮果胶提取液中盐析沉淀果胶.研究了盐析剂种类对果胶沉淀得率及盐折过程中pH值对果胶沉淀得率和果胶灰分含量的影响,并探索了适宜盐析条件和盐析机理.实验结果表明:以硫酸铝钾为柚皮果胶盐析剂,适宜盐析条件为:pH值5.8.盐析温度25℃,盐析时间30 min,果胶沉淀得率可达91.4%,采用三氯化铁盐析果胶,则pH值宜控制在4.0,于60℃下盐析60 min,果胶沉淀得率达95.8%.两种盐析方法所得果胶灰分均低于5.0%.铝盐盐析的果胶为白色,铁盐盐析的果胶颜色呈浅黄色,加入脱铁助剂Aid-4后可以获得较好的脱色效果.铁盐和铝盐盐析果胶的机理相似,都是果胶中的羧基离子取代金属水合物中的羟基,与金属离子发生配位反应,生成沉淀实现果胶从溶液中的分离.     

树莓中鞣花酸提取工艺的优化

以红树莓为原料,无水乙醇作为提取溶剂,采用超声波辅助提取红树莓中的鞣花酸,分析料液比、提取时间和提取温度对鞣花酸得率的影响,在单因素试验的基础上,利用响应面试验优化红树莓中鞣花酸提取工艺。结果表明,鞣花酸的最佳提取工艺条件为料液比1∶14.04(g/mL)、提取时间19.72min、提取温度80.02℃,此条件下鞣花酸得率为670.28μg/g,验证实验得率为675.134μg/g,相对误差0.72%,模型可靠。     

豆腐柴叶制取低甲氧基果胶工艺条件研究

以豆腐柴叶为原料,用氨——醇脱脂化法作制取低甲氧基果胶的工艺路线,采用正交设计法[L_(16)(4~4×2~3)]对高甲氧基果胶酰胺化过程中的五个主因子各水平进行最优化选择试验。结果表明,五个主因子的最佳参数为:酰胺化pH 11.0、时间12小时、温度30℃,中和反应pH1.2、时间2小时。在最佳参数下,制取的低甲氧基果胶主要质量指标为胶凝度(USA-SAG法)116级,酯化度36.70%,酰胺度21.05%。     

狐臭柴叶片中果胶提取条件的初步研究

以狐臭柴叶为原料、柠檬酸为酸解液提取果胶,采用单因素实验、正交实验对酸浓度、提取温度、料液比和提取时间等条件进行探索,并以响应面实验设计方法进行工艺优化。结果表明:酸浓度和料液比是影响果胶酸解的主要因子;一定范围内,酸浓度与果胶粗产率(Y1)呈线性正相关,料液比与果胶粗产率(Y1)呈线性负相关,二者与粗果胶半乳糖醛酸含量(Y2)的关系符合二元二次多项式方程模型,但随着酸浓度的增加和料液比的降低,半乳糖醛酸含量有下降趋势;半乳糖醛酸提取率(果胶有效提取率Y3)的拟合效果是一个平均值模型,即Y3=8.86%。在提取温度、提取时间分别为90℃和120 min,响应面的优化条件为酸浓度3.91%、料液比1∶44.09时,果胶粗产率、半乳糖醛酸含量和果胶有效提取率分别为36.72%、32.09%和11.78%。     

微波-超临界CO_2萃取联用萃取柚皮果胶工艺研究

采用超临界CO2萃取与微波处理技术相结合萃取柚皮果胶,探讨了微波辐射功率、萃取时间、萃取压力、萃取温度、CO2流量对柚皮果胶得率的影响,并采用正交试验对实验方案进行优化。研究结果表明:当原料用量5 g、微波辐射功率450 W、萃取时间15 min、萃取压力8.5 MPa、萃取温度40℃和CO2流量12 L/h时,果胶的平均得率22.63%,比相同条件下微波辅助水浴加热提取法的果胶得率高6.52个百分点。     

不同沉淀方法提取柚皮果胶的研究

柚皮经盐酸溶液提取而得果胶提取液,分别以醇沉法和盐析法从提取液中沉淀果胶.研究并获得了两种沉淀方法的最佳沉淀条件,比较了不同沉淀方法的乙醇消耗量,探索了不同沉淀方法对果胶沉淀得率和品质的影响.结果表明:醇沉法所消耗的乙醇量几乎为盐析法乙醇消耗量的两倍.盐析法能大大降低乙醇使用量,省去稀酸提取液浓缩工序和减少乙醇回收量,节省能耗,降低生产成本,并能保证较高的沉淀得率和果胶品质.     

正交试验法优选枇杷叶中科罗索酸提取工艺的研究

研究了枇杷叶中治疗Ⅱ型糖尿病有效成分科罗索酸的最佳提取工艺。以科罗索酸提取率为指标,通过正交试验考察了枇杷叶中4种三萜酸提取效果的影响因素,其最佳提取条件为:温度80℃,提取时间3.0 h,提取溶剂为80%乙醇溶液,料液比1∶14(g∶mL),分2次提取,科罗索酸得率为0.984%。     

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.     

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.