微波-超临界CO2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450W、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...     

超临界 CO2 萃取落叶松木材挥发油的工艺研究

采用超临界CO2萃取技术萃取落叶松木材挥发油,以得率为考察指标,研究了萃取压力、萃取温度、CO2流量和萃取时间对得率的影响.确定了超临界CO2萃取落叶松木材挥发油的最佳工艺参数:萃取压力35MPa,萃取温度60℃,CO2流量10kg/h,萃取时间2h,在此条件下挥发油得率可达0.57%.     

萃取及化学成分分析

研究了超临界CO2流体萃取柑橘皮精油的工艺条件并对其化学成分进行了分析。考察了在超临界CO2条件下,萃取时间、萃取压力、萃取温度、CO2流量和分离温度等因素对精油得率的影响,并通过正交试验优化得到最佳工艺条件,用GC-MS法测定柑橘皮精油的化学组成。结果显示最佳工艺条件为:萃取温度40℃,萃取压力20 MPa,分离温度50℃,萃取时间60 min,CO2流量25 kg/h。在此条件下,精油得率为0.86%。GC-MS测定结果显示柑橘皮精油主要由5,5’-二甲氧基-3,3’-二甲基-2,2’-联二萘-1,1’,4,4’-四酮组成(35.54%),其次还含β-羟基-甲基炔诺酮-甲基肟(24.60%)。     

用响应面法优化超临界CO_2萃取缬草油工艺

为了探讨超临界CO2萃取缬草油的优化工艺条件,以缬草油得率为考察指标,采用单因素试验和BoxBehnken设计,探讨萃取压力、萃取温度、萃取时间和CO2流量对缬草油得率的影响。结果表明:在萃取压力21 MPa、CO2流量20 L/h,萃取温度45℃条件下,萃取90 min,缬草油得率为(4.250±0.003)%,与模型预测值接近,表明所建回归模型可靠。     

萃取柿叶精油的工艺研究

通过单因素试验和正交试验研究了超临界流体萃取柿叶精油的影响因素,并对生产工艺进行了优化设计.试验结果表明,萃取压力、萃取温度、CO2流量、萃取时间对萃取得率的影响程度依次递减.最佳工艺条件为,100 g柿叶在萃取压力18 MPa、萃取温度50 ℃、CO2流量20 kg/h、萃取时间2.5 h,得率为3.1 %.用超临界CO2萃取柿叶精油比水蒸气法蒸馏的柿叶精油得率提高了55 %,萃取物纯度高,有浓郁的柿果香味,色淡黄.     

超临界CO2萃取荷叶挥发油工艺的研究

荷叶为多年生水生草本植物莲的叶,具有重要的药用价值.探讨了超临界CO2萃取的压力、温度、流量、时间等条件对荷叶挥发油收率的影响,确定其最佳萃取条件:萃取压力30 MPa,温度40℃,CO2流量25 kg/h和时间90 min,得率为4.36%,水蒸馏法提取率为1.65%.结果表明,超临界CO2萃取挥发油比传统的水蒸气蒸馏提取法质优,收率大大提高,萃取时间短,无溶剂残留.     

Extraction of Orange Peel Oil by SCF-CO2 and Analysis of Its Constituents

研完了超临界CO2流体萃取柑橘皮精油的工艺条件并对其化学成分进行了分析.考察了在超临界CO2条件下,萃取时间、萃取压力、萃取温度、CO2流量和分离温度等因素对精油得率的影响,并通过正交试验优化得到最佳工艺条件,用GC - MS法测定柑橘皮精油的化学组成.结果显示最佳工艺条件为:萃取温度40℃,萃取压力20 MPa,分离温度50℃,萃取时间60 min,CO2流量25 kg/h.在此条件下,精油得率为0.86％.GC-MS测定结果显示柑橘皮精油主要由5,5-二甲氧基-3,3-二甲基-2,2'-联二萘-1,1’,4,4'-四酮组成(35.54％),其次还合β-羟基-甲基炔诺酮-甲基肟(24.60％).     

超临界二氧化碳萃取披针叶黄华总生物碱工艺的研究

利用超临界CO2萃取(SCDE)的方法,研究了披针叶黄华萃取工艺,得到总生物碱.探讨了各种影响因素对披针叶黄华萃取得率的影响,通过正交试验确定了SCDE的最佳工艺为:萃取温度45 ℃、萃取压力20 MPa、CO2流量20 kg/h、萃取时间80 min.在此条件下,总生物碱得率3.12%.     

均匀设计法优化桦木醇的超临界二氧化碳萃取工艺

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.     

超临界二氧化碳萃取杨梅仁油的研究

采用超临界CO2流体萃取技术对杨梅仁中杨梅仁油的提取工艺进行优化研究.运用L9(34)正交表,探讨各因素对萃取效果的影响,并采用气-质联用仪对杨梅仁油的成分进行分析.结果表明:超临界CO2流体萃取得到的杨梅仁油品质好,在萃取压力35 MPa、萃取温度50 ℃、萃取时间60 min、CO2流量30 L/h、分离温度30 ℃时效果最佳,得率高达33.52%;杨梅仁油中脂肪酸以油酸、亚油酸为主,不饱和脂肪酸含量在83%以上,是一种质量很好的保健油.     

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.