豚草提取物微胶囊剂的制备与表征

本文利用微胶囊技术,以豚草提取物为囊芯材料,明胶为囊壁材料,采用单凝聚法制备豚草提取物植物源农药微胶囊剂,设计正交试验并对其性能进行表征。结果表明:豚草提取物微胶囊最优配比方案为明胶质量浓度5 g·L^-1,芯壁比1:2,搅拌速度200 r·min^-1,乳化时间90 min。其中,四因素对成囊影响由大到小排列顺序为,明胶质量浓度>搅拌速度>乳化时间>芯壁比。从扫描电子显微镜成像图片可以看出,微胶囊形状规则、表面光滑。微胶囊中位径为20.55μm,大部分粒径大小分布在18.23～33.31μm间。豚草提取物微胶囊剂缓释效果优于豚草提取物。     

羧甲基纤维素/蜜胺树脂相变纳米储能材料的制备与表征

以羧甲基纤维素(CMC)改性的蜜胺树脂作为壁材,以石蜡为芯材,采用原位聚合法,制备CMC改性的蜜胺树脂相变纳米胶囊。采用FTIR、DSC、SEM及光学显微镜等现代分析仪器对产物的性能进行分析和表征,探讨乳化剂种类和芯材乳液制备转速对胶囊制备过程的影响。结果表明,采用复配乳化剂制备的相变胶囊的性能要优于使用单一乳化剂制备的相变胶囊;当制备芯材乳液的转速为8 000 r/min时,芯材乳液的性能最好;所制得的相变胶囊为球形、平均粒径约为50 nm,且包裹完全、粒径均匀,相变焓为81.87 J/g。     

缓释型甲醛捕捉剂的制备及其在刨花板甲醛释放控制中的应用北大核心

为降低刨花板游离甲醛释放量,研究以尿素为功能性芯材,壳聚糖为壁材,采用乳化交联法制备具有缓释功能的微囊型甲醛捕捉剂,并将其应用于刨花板制备过程中。结果表明:在芯壁材比例为2∶1,水油比为1.5∶1,乳化剂用量2%的条件下制备的微囊型甲醛捕捉剂形状规则,平均粒径在50μm左右,芯材负载量和负载效率达到45.86%和68.76%。相较于未处理材,添加微囊型甲醛捕捉剂的刨花板在第1天、第14天、第28天的甲醛释放浓度分别降低了38.27%、49.74%和25.74%。以微囊型甲醛捕捉剂填充刨花板内部孔隙结构,在芯材缓释降解游离甲醛的同时,影响游离甲醛的扩散迁移路径,从而达到较好的甲醛控释效果。     

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...     

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。     

油茶籽油微胶囊凝聚法工艺技术的研究

以阿拉伯胶和明胶为壁材的凝聚法生产茶油微胶囊的工艺过程及条件如下5%阿拉伯胶和5%明胶与一定量油茶籽油在60℃下乳化1min,在pH4.4下凝聚0.5h,10℃下固化1h,经离心和真空干燥即可.该法制备的微胶囊,有较高的含油率和包埋率.其粒径与凝聚时的搅拌速度密切相关,但其水溶性较差.     

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%.     

肉桂叶精油/β-环糊精微胶囊的制备及缓释特性

为进一步拓宽肉桂精油在食品、饲料等领域的应用,以β-环糊精为壁材、肉桂叶精油为芯材,采用共沉淀法制备了肉桂叶精油/β-环糊精微胶囊,正交试验优化了微胶囊制备条件,并通过气相色谱-质谱联用(GC-MS)、傅里叶变换红外光谱(FT-IR)对制备的肉桂叶精油/β-环糊精微胶囊进行表征.研究结果表明:壁芯比6:1、包埋温度50...     

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7：1，乳化剂加入量为6％，乳化过程搅拌速度3000r／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％。     

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。     

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.