喷雾干燥制备角鲨烯微胶囊的研究

以明胶、阿拉伯胶和麦芽糊精复配作为壁材,蔗糖酯和聚氧乙烯脱水山梨醇单油酸酯(吐温-80)为乳化剂,采用超声波乳化-均质-喷雾干燥工艺制备角鲨烯微胶囊产品。对超声波乳化工艺、壁材配比、乳化剂添加量以及喷雾干燥等参数进行了研究,并将优化工艺所制备的产品与冷冻干燥法制备微胶囊进行比较。结果表明,产品的最佳工艺为:角鲨烯3.0 g,吐温-80为0.6 g,经超声波乳化后(功率240 W,时间4 min)与明胶2.0 g,阿拉伯胶2.0 g,麦芽糊精10.0 g,蔗糖酯0.5 g,按料液固体质量分数为3.88%的比例与水混合,在进风温度180℃,出风温度105℃,喷雾空气流速为1.5 m3/h,进料速率为6 m L/min的条件下进行喷雾干燥。此条件下,角鲨烯微胶囊包埋率92.3%,颗粒呈球形,粒径在12.0μm左右。喷雾干燥相较于冷冻干燥,所得微胶囊包埋率更高,产品颗粒呈球形,粒径更小,热性能也更加稳定。     

离心喷雾法制备橡胶籽油ω-3脂肪酸微胶囊的工艺研究

采用尿素包合法富集的橡胶籽油ω-3脂肪酸易氧化劣变,为防止产生氧化劣变,以单甘酯:蔗糖酯=1:5为乳化剂,大豆分离蛋白质、酪朊酸钠、麦芽糊精混合物为壁材,采用离心喷雾法制备橡胶籽油ω-3脂肪酸微胶囊,最佳工艺条件为:大豆分离蛋白质、酪朊酸钠和麦芽糊精之比为1:1:1.5,固形物浓度为20%(W/V)的溶液,进料速度20 mL/min,进风温度为160℃,出风温度为80℃。该工艺条件下制备的微胶囊ω-3脂肪酸包埋率达到93.8%,抗氧化性提高4.9倍。     

核桃粕制备微胶囊速溶核桃粉工艺研究

以冷榨核桃粕为原料,采用微胶囊包埋技术研究速溶核桃粉的制备工艺,为开发高品质核桃深加工产品提供技术。结果表明:添加2%蔗糖脂肪酸酯作乳化剂、0.9%的β-环糊精作稳定剂、乳化温度60℃,核桃液乳化稳定性好。采用微胶囊包埋技术,以明胶、麦芽糊精、β-环糊精为壁材配料,配方为1:4:4,芯壁材比例10:1,核桃粉包埋率可达85.63%。采用食品贮藏期加速测试法(ASLT)测得用上述工艺生产的微胶囊速溶核桃粉保质期可达12个月。     

银杏蛋白-海藻酸钠制备包埋植物乳杆菌微胶囊及其性能研究

植物乳杆菌作为一种益生菌,当人体食用足够量时,可以有益身体的健康。近年来,越来越多的益生菌已被作为辅料添加至食品中,但添加的益生菌在食品加工过程中易高温失活或者在人体胃肠道酸性环境下存活率显著降低。因此,为了提高益生菌在人体胃肠道内和贮藏期间的稳定性,以银杏蛋白和海藻酸钠为复合壁材,采用挤压法制备植物乳杆菌(Lactobacillus plantarum)微胶囊,得到包埋率高的微胶囊产品。通过单因素试验,考察了复合壁材质量浓度、菌液与壁材比例、Ca Cl2质量浓度、固化时间等对植物乳杆菌包埋效果的影响。在单因素试验的基础上,采用正交试验确定了制备微胶囊的最佳工艺参数。结果表明,植物乳杆菌微胶囊的最佳制备工艺如下:壁材质量分数为2.5%,菌液与壁材体积比为1∶2,Ca Cl2质量分数为5%,固化时间为20 min时,植物乳杆菌微胶囊的包埋率最高,可达86.33%。植物乳杆菌微胶囊在模拟胃液中具有较好的耐受性,肠溶性也较好,并且适宜在低温下贮藏。上述结果表明银杏蛋白-海藻酸钠复合壁材可以大大地提高植物乳杆菌微胶囊产品的稳定性。     

松香改性新型微胶囊壁材的制备研究

以松香、富马酸、亚硫酰氯为原料,制备了富马海松酸酰氯.以富马海松酸酰氯为油溶性单体,二乙烯三胺为水溶性单体,在稳定的乳化体系中两种单体在两相界面发生缩聚反应,生成立体网状结构的高分子聚合物囊壳,形成包油微胶囊.确定了富马海松酸酰氯制备反应的最佳条件和微胶囊化过程中的最佳乳化条件、成囊条件及最佳芯壁比.实验得出当芯壁比为71,乳化剂加入量为6%,乳化过程搅拌速度3 000r/min,成囊过程搅拌速度800r/min时,得到微胶囊包埋率为85.4%,包埋度为74.7%.     

水性涂料微胶囊的制备及其涂层自修复性能研究

采用乳液聚合法,以三聚氰胺甲醛树脂为壁材,以虫胶溶液、水性涂料为芯材制备自修复微胶囊,通过五因素四水平正交试验,探究W_芯∶W_壁、W_(乳化剂)∶W_芯、W_虫∶W_水、W_(乳化剂溶液)∶W_芯质量比与搅拌速率对微胶囊产量和包覆率的影响。结果表明:搅拌速率对微胶囊的影响较大。当W_芯∶W_壁为0.8∶1,W_(乳化剂)∶W_芯为3∶100,搅拌速率为600 r/min,W_(虫胶)∶W_(涂料)为1∶1,W_(乳化剂溶液)∶W_芯为9∶1时,制备的微胶囊具有较好的形状和尺寸。将该微胶囊加入水性涂料,随着微胶囊浓度的增加,漆膜的色差和光泽度逐渐减小。随后对漆膜的拉伸强度、表面形貌、化学成分及修复效果进行了分析,当微胶囊添加量为5.0%～10.0%时,漆膜的修复效果明显。当微胶囊添加量为5.0%时,漆膜综合性能较好。研究结论为木质家具自修复涂层的研发提供理论依据。     

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。     

绿僵菌分生孢子微胶囊乳液制备研究

金龟子绿僵菌(Metarhizium anisopliae var.anisopliae)是一种重要的真菌,常用于防治林业害虫,但其分生孢子制剂不耐贮藏,且高温、干燥、强紫外光等环境条件影响其田间防治效果.为增强绿僵菌分生孢子的贮藏性及野外应用的抗逆性,该研究探索了水包油法制备绿僵菌分生孢子微胶囊乳液的技术工艺.结果表明,以辛烯基琥珀酸淀粉钠为壁材料,绿僵菌孢子粉(分散于大豆色拉油中)为芯材,其最佳组合和制备条件为,壁材料∶芯材料(m/m) =10∶1,其中大豆色拉油∶孢子粉=3∶1,乳化剂为0.5％吐温-80,剪切速度为13 000 rmp,剪切时间为1 min,制成微胶囊乳液的包覆率和萌发率分别达到75.53％、82.50％.     

漆脂基脂肪粉的制备工艺及性质研究

以漆脂为芯材,采用不同种类的壁材进行复配,并通过喷雾干燥制备漆脂基脂肪粉,以乳化能力和包埋率为指标,通过单因素试验优化了漆脂基脂肪粉的制备工艺:壁材为麦芽糊精/大豆分离蛋白(4∶1,质量比,下同),乳化剂为蔗糖脂肪酸酯/单硬脂酸甘油酯(8∶2),乳化剂添加量为3.5%(以芯壁总质量计,下同),阿拉伯胶添加量为2.5%,壁芯质量比为2∶1,乳液含总固形物30%,在此条件下制得的乳液的乳化能力为94.2%,漆脂脂肪粉的包埋率为83.46%。红外光谱分析表明漆脂脂肪粉的包埋结构初步形成; GC-MS检测发现乳化和喷雾干燥对漆脂主要脂肪酸组成基本没有影响,漆脂脂肪粉含有68.329%的棕榈酸、19.245%的油酸和8.673%的硬脂酸;扫描电镜和粒径分析显示漆脂脂肪粉呈球形,分布较为均匀,粒径主要分布在1～5μm;加速氧化储藏试验表明经过微囊化包埋处理30天后,漆脂的过氧化值(67.8 mmol/kg)明显高于漆脂脂肪粉(27.2 mmol/kg),说明微胶囊包埋能够有效减缓漆脂的氧化酸败。     

水性涂料芯材微胶囊的制备及对椴木表面涂层性能影响

采用原位聚合法,以脲醛树脂为壁材、水性丙烯酸涂料为芯材制备微胶囊.探求芯壁比(质量比)、陈放时间和水浴温度对微胶囊形貌、产量和包覆率的作用,进行了 3因素2水平的正交实验,确定了陈放时间和水浴温度对微胶囊性能影响不大,影响最大的因素为芯壁比.为了进一步优化微胶囊性能,以芯壁比为单一变量进行单因素独立试验,发现随着芯壁比...     

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.