-环糊精包合一体化技术研究

采用超临界CO2流体萃取技术,研究紫苏油提取工艺条件,利用β-环糊精超临界微胶囊技术,研究紫苏油超临界包合一体化工艺条件.研究结果表明,制备紫苏油微胶囊的优化条件为:紫苏籽超临界萃取紫苏油的超临界压力 23 MPa,β-环糊精最佳超临界包合压力 12 MPa;包合反应时间 180 min,包合反应温度 55 ℃,萃取剂CO2流量 40 L/min.按此条件制得的紫苏油环糊精包合物,α-亚麻酸包合率为 16.37 %,最高包合物质量分数为 16.42 %,最高包合比(β-环糊精与紫苏油物质的量比)达1.84: 1;平均包合物质量分数为 13.94 %,平均包合比1.55: 1.     

西番莲籽油的超临界CO_2萃取及其特性分析

采用超临界CO2萃取(SCDE)技术从西番莲籽中提取油脂,探讨了萃取工艺条件对油脂提取率的影响,并对西番莲籽油的理化性质和脂肪酸组成进行了分析.研究结果表明,SCDE西番莲籽油的最佳工艺条件为:原料粒径 270 μm,萃取压力 20 MPa,萃取温度 50 ℃,分离釜Ⅰ温度 40 ℃、压力 8 MPa,分离釜Ⅱ温度 40 ℃,压力与CO2钢瓶的压力一致,萃取时间 3 h,在此条件下油脂得率达到了 25 % 以上.SCDE的西番莲籽油色泽明亮,澄清透明,其理化性质明显优于溶剂法提取的油脂,不饱和脂肪酸质量分数高达 89.43 %,其中亚油酸质量分数 72.69 %.     

文冠果籽油的超临界萃取及其脂肪酸组成

为了更加科学而有效地开发与利用文冠果,应用CO2超临界萃取技术,对文冠果籽油的提取工艺条件进行了试验研究,并对超临界萃取的文冠果籽油的各项理化指标值和脂肪酸组成进行了测定与分析。提取试验结果表明,CO2超临界萃取文冠果籽油的工艺条件为:萃取压力30 MPa,萃取温度50℃,C O2流量40 L/h,萃取时间150 min;在此条件下出油率可达44.56%。测定结果表明:文冠果籽油的折光指数n20为1.474 5,相对密度d20为0.917 3,其水分与挥发性物质的含量为0.38%,酸值0.51 mg/g,过氧化值0.000 9 g/g,碘值1.214 g/g,皂化值214 mg/g;超临界萃取的文冠果籽油主要含有亚油酸(40.9%)、油酸(29.5%)、芥酸(8.89%)、棕榈酸(4.95%)、硬脂酸(2.13%)和亚麻酸(0.4%)、花生四烯酸(0.02%)及山嵛酸(0.53%),其中不饱和脂肪酸的总含量为82.22%。     

紫苏籽的超临界CO_2萃取及β-环糊精包合一体化技术研究

采用超临界CO2流体萃取技术,研究紫苏油提取工艺条件,利用β-环糊精超临界微胶囊技术,研究紫苏油超临界包合一体化工艺条件。研究结果表明,制备紫苏油微胶囊的优化条件为:紫苏籽超临界萃取紫苏油的超临界压力23 MPa,β-环糊精最佳超临界包合压力12 MPa;包合反应时间180 min,包合反应温度55℃,萃取剂CO2流量40 L/min。按此条件制得的紫苏油环糊精包合物,α-亚麻酸包合率为16.37%,最高包合物质量分数为16.42%,最高包合比(β-环糊精与紫苏油物质的量比)达1.84∶1;平均包合物质量分数为13.94%,平均包合比1.55∶1。     

超临界二氧化碳萃取装置及其萃取沙棘油的研究

以沙棘籽和沙棘果皮为原料，以无毒，易得，价廉的CO2为萃取剂，采用超临界萃取方法，提取出质量高，无残留溶剂的沙棘籽油（常温下是液体）和沙棘果皮油（常温下是固体）。通过对原料粒度，萃承压力，萃取温度，萃取时间,萃取剂CO2流量不同条件的实验，获得较佳的工艺参数。工艺流程简单，操作方便。     

榛子油提取工艺的研究

以干燥粉碎后的榛子仁为原料,研究应用超临界CO2流体萃取榛子油的工艺.通过单因素试验、正交试验及方差分析得出,超临界CO2萃取榛子油的最佳工艺条件：萃取压力30 MPa,萃取温度55℃,分Ⅰ压力10 MPa,分Ⅰ温度40℃,萃取2h,萃取率达84％以上.     

超临界CO_2萃取油茶籽油的工艺及其脂肪酸成分分析

采用超临界CO2萃取技术对油茶籽进行萃取,提取油茶籽油。考察了油茶籽平均粒径、萃取压力、萃取温度、CO2流量和萃取时间对油茶籽油萃取率的影响,在单因素实验基础上进行了3因素3水平的正交试验,并对试验得到的油茶籽油进行了气相色谱分析。超临界CO2萃取油茶籽油的最佳实际工艺条件为:油茶籽平均粒径0.605mm、萃取压力30MPa、萃取温度50℃、CO2流量30L·h-1和萃取时间90min,最佳实际工艺条件下油茶籽油萃取率为91.17%。气相色谱分析表明,油茶籽油脂肪酸主要由5种脂肪酸组成,其中不饱和脂肪酸占脂肪酸总量的88.28%。     

超临界CO_2萃取野生黄刺玫果籽油试验

对超临界CO_2萃取野生黄刺玫果籽油的工艺进行了单因素试验,分析了不同萃取压力、萃取温度、萃取时间以及原料粒度对黄刺玫果籽油萃取率的影响。结果表明,超临界CO_2流体萃取黄刺玫果籽油的较佳条件为:1 L萃取釜装料量200 g,萃取压力25 MPa,温度40℃,萃取时间为2 h,原料粒度40目。     

沙棘籽含水量对沙棘油品质的影响

讨论了沙棘籽含水量对超临界CO2萃取沙棘油品质的影响,特别是对酸价、维生素E含量、碘价的影响,当沙棘籽含水量〈7％时,超临界CO2萃取的沙棘油品质达到商品化要求。     

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。     

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

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.     

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.     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.