木质纤维素接枝丙烯酸系吸附剂的合成技术研究

在离子液体中,以木质纤维素为基质,分别采用过硫酸铵和氧化--还原体系为引发剂,N,N′-亚甲基双丙烯酰胺为交联剂,与丙烯酸及丙烯酸丁酯反应,利用接枝聚合合成技术制备了纤维素改性吸附剂。用石蜡为分散相,经反相悬浮技术将接枝物球化。对产物进行了热重分析,并通过接枝率、接枝效率及金属离子吸附量对各个产物进行了对比,结果表明,氧化———还原引发下制得的共聚物吸附效果最佳,且对铜离子吸收最为敏感,最大吸附量可达218.3mg/g。     

微晶纤维素氰乙基化及其反应动力学研究

通过微晶纤维素的氰乙基化试验,研究了反应温度和反应时间对氰乙基化产物取代度(DS)的影响,表明在50℃以下,微晶纤维素的氰乙基化取代度随反应温度的升高和反应时间的延长而增加。傅里叶红外光谱分析显示微晶纤维素氰乙基化后羟基峰明显减弱,并形成了新的碳氮三键吸收峰,证明纤维素中的部分羟基氢被氰乙基所取代。X射线衍射分析显示微晶纤维素中原有的结晶结构被破坏。X4显微熔融温度测定仪、维卡软化点测定仪等的分析表明微晶纤维素氰乙基化产物的热塑性先随取代度的升高而提高,取代度超过1.43后,产物的热塑性又随取代度的升高而下降。确定了微晶纤维素氰乙基化在不同温度(30、35、40和45℃)下的反应速率常数(分别为1.30、1.61、1.94和2.26 s-1),计算出了微晶纤维素氰乙基化反应的表观活化能为29.8 kJ/mol。     

纤维素C_6位伯羟基的选择性氧化及用于双酚A的吸附研究

采用HNO3/H3PO4-NaNO2氧化体系制备了氧化纤维素,通过红外光谱、固体13C NMR对其结构进行表征,用酸碱中和滴定法测定了产物的羧基含量。同时以氧化纤维素为吸附剂,研究了对水中内分泌干扰物双酚A(BPA)的吸附性能。结果表明:该氧化体系能很好的选择性氧化纤维素的C6位伯羟基,含羧基为20%。在298 K时,氧化纤维素对双酚A最大吸附量为12.67 mg/g,吸附平衡时间为30 min,平衡吸附量随双酚A浓度增加而增加;溶液接近中性及低温条件有利于吸附的进行,溶液中存在电解质则不利于吸附的进行。双酚A的吸附过程属于单分子层吸附,以化学吸附为主,符合准二级动力学方程和Langmuir吸附等温模型。     

二醛基纤维素的制备及其对尿素的吸附性能

以微晶纤维素为原料,高碘酸钠作为氧化剂,制备二醛基纤维素(DAC),考察各影响因素对二醛基纤维素制备的影响,采用FTIR、元素分析、XRD以及化学官能团测定等手段对二醛基纤维素的结构进行表征;探讨二醛基纤维素的醛基含量与尿素吸附容量之间的关系,并研究二醛基纤维素对尿素的吸附平衡和吸附动力学。结果表明:高碘酸钠与微晶纤维素的质量比为2.4∶1、反应温度为35℃、反应时间为3.5 h、反应介质的pH为2时,制得二醛基纤维素的醛基含量最大为97.74%。二醛基纤维素对尿素的吸附容量随醛基含量的增加先增大后减小,最大吸附容量为59.23 mg.g-1,是包醛氧淀粉尿素吸附容量的10倍(6 mg.g-1),是包醛酶淀粉吸附容量的4倍(15 mg.g-1),吸附平衡时间为4 h。吸附等温线符合Freundich方程。     

端氨基超支化聚合物接枝双醛基纳米纤维素的 制备及其对Ni2+的吸附

通过聚合反应制得一种端氨基超支化聚合物(HBP-NH_2),并以桉木浆为原料,经超声波辅助-TEMPO氧化制得羧基化纳米纤维素(CNC)、再经高碘酸钠氧化制得双醛基纳米纤维素(DNC),最后利用HBP-NH_2对DNC进行氨基化改性,得到端氨基超支化聚合物接枝双醛基纳米纤维素(HBPN-DNC),并对反应条件进行优化,当10%的HBP-NH_2溶液加入量为10 mL,反应温度为70℃,反应时间为4 h时N元素质量分数最高,达到6.0%。采用多种方法对纳米纤维素的结构和性能进行了表征,结果表明:氨基成功地接枝到了纳米纤维素链上,使得分子链变长,HBPN-DNC的热稳定性提高。HBPN-DNC对Ni(II)的吸附性能研究表明:室温条件下,当HBPN-DNC吸附剂用量为0.1 g,溶液初始质量浓度为500 mg/L且pH值为5.0的条件下吸附3 h,吸附量为150.21 mg/g。吸附过程符合准二级动力学吸附模型和Langmuir等温吸附模型,说明其吸附过程主要为单分子层的化学吸附。     

对伞花烃及其裂解产物甲苯的间接电解氧化反应研究

在无隔膜电解槽中,Pb-Sb合金为阳阴电极,Mn2 电解氧化成Mn3 的理想条件为:极板面积比(A /A-)为5:1,硫酸浓度为5 mol/L,阳极电流密度为80 mA/cm2,Mn2 浓度为1 mol/L左右,温度在25～35 ℃,电量比值为1.20.此时电解电流效率在60%左右,Mn3 得率超过70%.Mn3 氧化对伞花烃得到的主要产物为对甲基苯乙酮和枯茗醛,Mn3 与对伞花烃摩尔比为4:1时,氧化产物中枯茗醛的选择性相对较高,对甲基苯乙酮和枯茗醛的得率分别为55.19%和31.64%.Mn3 氧化甲苯得到的主要产物为苯甲醛,合适的氧化条件是Mn3 与甲苯摩尔比为1:6,苯甲醛的得率为73.67%.电解液经正己烷萃取和活性炭吸附可再生循环使用8次以上.     

纸浆纤维素苄基化及其反应动力学

通过纸浆纤维素的苄基化试验,研究反应温度和反应时间对苄基化产物取代度的影响,证明适当延长反应时间、提高反应温度有利于提高产物的取代度。傅里叶红外光谱仪、差示扫描量热仪、X射线衍射仪等对纸浆纤维素苄基化产物的分析表明:原料中的部分羟基被苄基取代,原有的结晶结构被破坏,产物热稳定性略有下降。维卡软化点和熔融温度测试显示产物的热塑性随取代度的增加而增加。本文还确定纸浆纤维素苄基化在4个不同温度下的反应速度常数,计算出纸浆苄基化反应的表观活化能为46.1kJ·mol-1。     

利用FTIR对苯基异氰酸酯与不同含水率纤维素反应的研究

通过FTIR红外光谱对苯基异氰酸酯与醇、水、不同含水率纤维素反应产物的研究 ,确定了产物的红外光谱吸收峰的归属。研究发现 :异氰酸酯与绝干纤维素羟基反应产物是氨基甲酸酯 ,随着纤维素含水率的增加 ,异氰酸酯与纤维素的反应越来越低 ,与水反应的比例越来越高 ;当纤维素含水率为 9 78%时 ,异氰酸酯绝大部分与水反应生成取代脲     

端氨基纳米纤维素的制备及对Pb(Ⅱ)的吸附性能研究

以桉木浆为原料,经TEMPO氧化制得羧基化纳米纤维素(CNC)、再经高碘酸钠氧化制得双醛基纳米纤维素(DANC),最后利用二乙烯三胺(DETA)通过席夫碱反应对其进行氨基化改性,得到端氨基纳米纤维素(ANCC)。采用多种方法对纳米纤维素的结构和性能进行了表征,结果表明:DANC含醛基为2.95 mmol/g,ANCC含氨基为1.7 mmol/g,DETA上的氨基成功地接枝到了纳米纤维素链上,使得分子链变长,ANCC的热稳定性提高。ANCC对Pb(Ⅱ)的吸附性能研究表明:室温条件下,当ANCC吸附剂用量为0.1 g,溶液初始质量浓度为400 mg/L且p H值为5.0的条件下吸附3 h,吸附量为210.15 mg/g。吸附过程符合准二级动力学吸附模型和Langmuir等温吸附模型,说明其吸附过程主要为单分子层的化学吸附。     

甘蔗渣基离子吸附剂的研究

以甘蔗渣为原料,用丙烯腈和盐酸羟胺对其进行改性,在甘蔗渣分子中引入胺肟基团,提高其对金属离子的吸附能力.讨论了羟胺化反应条件如温度、时间、羟胺质量浓度对胺肟基团含量的影响.用红外光谱表征了产物的结构,用元素分析法测试了产物中氮元素的含量.在反应温度90℃、反应时间180min、羟胺质量浓度100g/L时,改性甘蔗渣中最大含氮元素为13.4%,最大含胺肟基团为3.38mmol/g,并对改性产物进行了铜离子的吸附研究,其最大铜离子吸附量为54.0mg/g.     

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.