疏水性离子液体[C_4mim][PF_6]对木质纤维预水解液的脱毒作用

将稀酸蒸汽爆破预处理后的玉米秸秆进行预水解,以离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C_4mim][PF_6])萃取脱除预水解液中的抑制物,并对萃取脱毒条件进行优化,进一步分析了离子液体的脱毒效果。研究结果表明,最佳萃取条件为:水油相体积比1∶2、35℃、250 r/min下萃取60 min。在此条件下,水解液中的主要抑制物甲酸、乙酸、乙酰丙酸、5-羟甲基糠醛、糠醛和总酚的去除率分别达到24.72%、21.84%、47.99%、82.76%、100%和39.70%,且可发酵性糖几乎无损失。通过对主要抑制物与离子液体脱毒性能分析可知,随着离子液体[Cnmim][PF6](n=4,6,8)中阳离子烷基碳链增长,离子液体对抑制物萃取能力下降;抑制物疏水性越强,与离子液体的氢键作用越强,萃取分离效果越好;p H值越低,对抑制物的去除效果越好;乙酸、5-羟甲基糠醛、4-羟基苯甲醛在[C_4mim][PF6]中去除率基本不随抑制物初始质量浓度改变而发生变化。     

离子液体在天然活性成分分离中的应用研究进展

离子液体是由阴、阳离子组成的低温熔融盐,几乎没有蒸汽压,稳定性好,溶解能力强,结构可设计,优点突出,被认为是可替代传统溶剂的新型"绿色溶剂",在天然产物的提取分离研究中应用广泛。本文从离子液体联用超声波、微波、双水相萃取、酶法辅助与固相萃取等方面,综述了近年来离子液体在黄酮、萜类、生物碱、色素等天然成分提取分离中的应用情况,介绍了离子液体与其它技术联用的性质和分离机制,探讨了离子液体选择性差、黏度高、回收难及流失严重等问题,并提出了相应的解决思路,以期为离子液体在天然活性成分分离方面的应用提供借鉴和参考。     

虎杖酶解液中白藜芦醇萃取工艺初步研究

为了对虎杖(Polygonum cuspidatum Sieb.et Zucc.)酶解液中白藜芦醇的萃取工艺进行研究,以白藜芦醇的含量和萃取率为考察指标,筛选虎杖酶解液中白藜芦醇的萃取溶剂,对pH值、液-液比、萃取次数进行考察,采用正交试验优化白藜芦醇的萃取工艺。结果得出,在pH值为6、液-液比为1∶3、萃取3次,白藜芦醇得率达到90.54%。该优化工艺适用于虎杖酶解液中白藜芦醇的萃取。     

发泡木塑复合材料中甲酰胺释放量的测定

为有效规范发泡木塑复合材料中偶氮二甲酰胺的使用,本文建立了微波辅助萃取气相色谱质谱法测定甲酰胺的分析方法,并考察了萃取溶剂对试验体系的影响。结果表明,采用丙酮为萃取溶剂,70℃下萃取30 min,利用选择离子扫描,甲酰胺在0.01~1.0 mg/L线性范围内质量浓度与响应值呈现良好的线性关系,加标回收率为98%~116%,相对标准偏差2.4%~6.2%,该方法操作简单,提取效果较好,能够有效的检测发泡木塑复合材料中甲酰胺释放量。     

萃取-酯交换耦合法制备生物柴油过程催化剂应用研究进展

传统的生物柴油生产过程通常包括油脂提取、提纯精炼、酯化/酯交换等步骤,需要消耗大量的能源与化学品。萃取-酯交换耦合技术是近年来开发的一种简单有效、具有较大应用潜力的生物柴油制备方法,该方法直接以含油固体为原料,以短链醇等作为萃取溶剂和酯交换反应试剂,油脂萃取与酯化/酯交换反应同时进行,提高了生产效率,降低了生产成本,减少了环境污染。萃取-酯交换耦合法中催化剂的选择是反应能否实现高效转化的关键。酯交换反应的催化剂种类繁多,但大多数针对的原料是浸提过的液体油脂,较少用来催化固体原料原位酯交换反应。笔者综述了近年来萃取-酯交换耦合技术制备生物柴油的研究进展,包括酸催化法、碱催化法、离子液体催化法、超临界法和生物酶法,探讨了各种方法的优缺点,同时提出了萃取-酯交换耦合法制备生物柴油过程中催化剂制备与应用方面需要解决的主要问题及今后的发展方向。     

万通离子色谱仪测定PM2.5中水溶性阴离子

采用万通离子色谱测定PM_2.5中水溶性阴离子,在碳酸根-碳酸氢根体系下通过使用带英蓝超滤单元,从空白试验、方法检出限、标准曲线、实际样品比对等方面进行了方法验证。结果表明：使用Metrosep A Supp 5-150/4.0型阴离子色谱柱,流速0.7 mL/min、柱温30℃,16 min内可完成4种阴离子分离,该方法标准曲线线性良好,相关系数大于0.999,实验室空白、全程序空白、检出限和样品的精密度、准确度均能达到质控要求,不同离子色谱仪测定实际样品比对结果良好。该方法操作简单,适用于PM_2.5中水溶性阴离子的测定。     

纤维素在四己基醋酸铵/助溶剂混合体系中的溶解及再生

纤维素在自然界中储量丰富,是一种很好的生物质资源,但纤维素中含大量氢键,很难溶于常见有机溶剂,开发有效的纤维素溶解体系是纤维素应用的重点和难点。相对传统纤维素溶剂而言,离子液体具有对纤维素溶解性好,低毒性、难挥发等优点,成为近几年的研究热点。本研究通过离子交换法合成了四己基醋酸铵(THAA)离子液体,并分别以二甲基亚砜(DMSO)、N,N-二甲基乙酰胺(DMAc)和N,N-二甲基甲酰胺(DMF)为助溶剂对不同纤维素原料微晶纤维素、滤纸等进行溶解。探讨助溶剂类型、THAA含量、溶解温度和纤维素聚合度对THAA/助溶剂混合体系溶解纤维素的影响。结果表明,DMSO对纤维素溶解有促进作用,DMAc和DMF效果不大。当THAA/DMSO混合体系中THAA质量分数为30%时溶解纤维素性能最佳,25℃下能溶解7.51%的微晶纤维素。此外,纤维素在此溶剂体系中的溶解速度随溶解温度的升高及纤维素聚合度的降低而提高。纤维素经THAA/DMSO混合体系溶解再生后纤维素晶型由Ⅰ型变成Ⅱ型。     

[Psmim]HSO_4离子液体催化液化木材及其产物表征

合成了1-磺酸丙基-3-甲基咪唑硫酸氢盐离子液体([Psmim]HSO4),对其结构进行了傅里叶红外光谱(FT-IR)和核磁共振(13C NMR)表征。以正辛醇为溶剂,初步考察了该离子液体对杉木屑液化的催化性能,并对残渣、重油和轻油液化产物进行了FT-IR、X射线粉末衍射(XRD)、热重分析(TG)、气质联用(GC-MS)表征。FT-IR和13C NMR分析结果证实了合成产物与目标离子液体结构一致。液化实验结果表明该离子液体具有较好的催化液化性能,10 g杉木屑、60 g正辛醇在催化剂用量8.6 mmol、150℃、60 min条件下,木屑的液化率达66.5%。液化残渣表面的木质素衍生物含量高;轻油主要由纤维素和半纤维素的液化产物组成,重油主要由木质素的液化产物组成。     

漆籽漆蜡超临界CO2萃取工艺研究

采用超临界CO₂流体萃取技术对漆籽中漆蜡的提取进行了研究。通过单因素试验考察了萃取时间、萃取压力、萃取温度以及分离釜Ⅰ压力、分离釜I温度对漆蜡得率的影响。根据单因素试验结果,选择萃取釜压力、萃取温度、分离釜Ⅰ压力、分离釜Ⅰ温度作为考察因素,以漆蜡得率为评价指标,用正交试验对整个萃取工艺进行优化。结果表明：漆蜡最佳萃取条件为萃取釜压力30 MPa、萃取釜温度55℃,分离釜Ⅰ压力12 MPa、温度为55℃,分离釜Ⅱ压力为6 MPa、温度为50℃,分离釜Ⅲ压力为6 MPa、温度为50℃,萃取时间120 min。在此工艺条件下,漆蜡的平均萃取得率为36.45%。GC-MS分析显示,超临界CO₂流体萃取漆蜡的脂肪酸组成主要为棕榈酸、硬脂酸、亚油酸、油酸及二十烷酸(花生酸),其中棕榈酸、油酸和硬脂酸约占92%～95%。理化性质分析显示,超临界CO₂流体萃取漆蜡的熔点53℃、酸值21.61～25.96 mg·g^-1、碘值34.79～36.82 g·100 g^-1、皂化值198.29～214....     

离子液体在光催化剂制备中的应用

指出了离子液体因具有熔点低、蒸汽压低、导电性良好等优点而被认为是新一代的"绿色溶剂",受到人们广泛的关注和研究。目前,离子液体已经被开发应用到电化学、有机合成、无机合成等诸多领域。介绍了离子液体的合成方法,并针对其在光催化剂制备中的应用的研究进展进行了阐述,也对离子液体的进一步发展进行了展望。     

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.