漆酶活化木素磺酸盐条件对胶合板强度的影响

采用漆酶活化木素或其磺酸盐制备胶黏剂用于人造板生产,可以消除游离甲醛的污染问题。以漆酶、工业木素及其磺酸盐、杨木为原料,在处理时间分别为30、45、60min,pH值分别为3．5、4．5、5．5,温度20℃条件下,分别以漆酶处理工业木素、木素磺酸钠和木素磺酸铵三种底物制备胶黏剂,然后在热压时间30min,压力4．5～5MPa,热压温度150℃条件下生产杨木胶合板。结果表明,除漆酶木素磺酸钠胶合体系外,漆酶木素和漆酶木素磺酸铵的胶合体系的胶合板胶合强度均达到并超过国家Ⅲ类胶合板的要求。     

邻苯二酚基多糖交联剂合成与表征及其对豆胶性能影响

仿照贻贝蛋白高黏附结构,合成邻苯二酚基多糖交联剂(CP)用以增强大豆蛋白胶黏剂的耐水胶接性能,研究CP原料中玉米淀粉与叔丁基二甲基氯硅烷保护的3, 4-二羟基苯甲酸(DHBAT)质量比、CP加入量、胶合板热压工艺(涂胶量、热压温度和热压时间)对大豆蛋白胶黏剂制备胶合板耐水胶接性能的影响规律,表征CP和改性大豆蛋白胶黏剂(SPI-CP)的功能性基团以及胶黏剂热稳定性、结晶区间、断面形貌等解析CP对大豆蛋白胶黏剂的增强机制。试验结果表明：通过4-二甲基氨基-吡啶和N, N-二环己基碳二亚胺催化的酯化反应将邻苯二酚结构成功接枝到玉米淀粉制成CP;CP的最佳配方为m(多糖)∶m(DHBAT)=1∶2,加入量为6%。SPI-CP胶黏剂制备胶合板耐水胶合强度较未改性时提高了64.62%,达1.07 MPa,干状胶合强度提高了154.44%,达2.29 MPa,满足国家标准中的Ⅱ类胶合板要求。这归因于CP中的邻苯二酚结构氧化形成醌类结构与蛋白氨基发生席夫碱反应,形成化学键交联,增强胶黏剂的耐水胶接性能;SCI-CP胶黏剂制备胶合板的优化热压工艺参数为热压温度130℃,热压时间4.5 min(板坯厚4...     

丙烯酸树脂豆基胶黏剂的研究

以丙烯酸树脂作为交联剂,制备共混改性豆基胶黏剂。探讨了助剂加入量、助剂种类、胶液pH值及热压温度对胶合板的胶合强度与耐水性的影响。结果表明:当助剂加入量为胶液的3/1 000、助剂为聚氯化铝、胶液pH值为3.75时,压板工艺为热压时间6 min、热压压力1.1 MPa、热压温度125℃时,胶合板胶合强度为0.74 MPa,符合GB/T9846—2015中Ⅱ类胶合板强度要求。     

改性豆基蛋白胶黏剂的胶合工艺初探

以杨木单板为试材研究了改性豆基蛋白胶黏剂的胶合性能,采用单因素实验方法,探讨了改性豆基蛋白胶黏剂压制胶合板的胶合工艺。分析了热压温度、热压时间和涂胶量对三层杨木胶合板胶合性能的影响。结果表明:采用改性后的豆基蛋白胶黏剂,在压力为1.4MPa,温度为165℃左右,热压时间为1.4～1.6 min/mm,涂胶量为220g/m~2,压制的杨木胶合板胶合性能较佳且达到Ⅰ类胶合板的标准。     

油菜籽蛋白-丙烯酸酯乳液共混胶黏剂的制备

将油菜籽蛋白和丙烯酸酯乳液共混制备胶黏剂,以其代替部分醛类胶黏剂用于胶合板生产。采用单因素试验方法,确定油菜籽蛋白和丙烯酸酯乳液添加比例;采用正交试验方法,优化该胶黏剂制备胶合板工艺;通过热重分析评价胶黏剂的热稳定性。结果表明:油菜籽蛋白与丙烯酸酯乳液配比为8∶2,胶合板制备理想的热压工艺为二苯甲烷二异氰酸酯(MDI)添加量4%、热压温度140℃、热压时间700s、热压压力0.8MPa,板材剪切强度1.71MPa,符合GB/T9846—2015《普通胶合板》中Ⅱ类胶合板的要求。     

聚酰胺多胺环氧氯丙烷树脂大豆胶黏剂制备及性能研究

采用己二酸(AA)、二乙烯三胺、环氧氯丙烷(ECH)合成聚酰胺多胺环氧氯丙烷树脂(PAE),将其与大豆蛋白按比例混合制备PAE大豆胶黏剂。在合成预聚体(PA)后,通过单因素试验,探究AA与ECH摩尔比、大豆蛋白添加量对胶合板胶合强度的影响,研究了PAE对大豆蛋白的改性作用及胶接机理。结果表明:在胶黏剂合成过程中AA与ECH摩尔比为1:1.0,大豆蛋白添加量为30%,热压温度为120℃、压力1.0 MPa、热压时间6 min条件下,PAE大豆蛋白胶黏剂胶合强度可达1.02 MPa,满足GB/T 9846-2015Ι类板指标要求。     

改性大豆蛋白胶黏剂制造杨木胶合板热压工艺

利用单因素试验方法,研究了热压温度、热压时间、热压压力和施胶量对使用改性大豆蛋白胶黏剂制造的杨木胶合板胶合强度的影响规律.结果表明:在100～ 220℃热压温度范围内,随着热压温度的增加,胶合强度显著增大;在35～60 s/mm热压时间范围内,胶合强度随热压时间的增加呈上升趋势,当时间从60 s/mm升至85 s/mm,胶合强度几乎保持一致;热压压力在1.25 MPa时,胶合强度达到最大值;施胶量在130 ～430g/m2热压时间范围内,胶合强度随施胶量的增加呈上升趋势.由此得出最优工艺参数为:热压温度180℃,热压压力1.25 MPa,热压时间60 s/mm,施胶量为310g/m2.     

小球藻蛋白基胶黏剂的制备及其胶合性能研究

小球藻蛋白具有可再生、价格低廉等优点,可用于制备蛋白基胶黏剂。采用氢氧化钠(Na OH)、十二烷基硫酸钠(SDS)和三羟甲基丙烷三缩水甘油醚(TTE)改性处理小球藻蛋白后制备胶黏剂。多种方式表征结果显示,改性处理破坏了小球藻蛋白的球形结构,提供了更多的交联位点,从而提高了胶黏剂的胶合强度及耐水性能。在优化工艺参数:双面涂胶量400g/m2,热压压力1.5 MPa、热压温度150℃、热压时间8 min的条件下,制备的三层桉木胶合板的干、湿胶合强度分别为1.78、1.11 MPa,满足GB/T 9846—2015《普通胶合板》中II类胶合板的要求。     

豆胶的热反应特性及胶合特性分析北大核心

大豆蛋白胶因其可再生、可降解和环保性而受到广泛关注。豆胶的热反应特性和胶合特性研究结果显示:以20℃/min速率升温时,豆胶胶液在157℃时完全固化,在173℃开始降解;胶合板的胶合强度与涂胶量呈线性正相关。按热压温度160℃、热压时间80s/mm、压力1.6MPa、双面涂胶量450g/m2的工艺制备豆胶胶合板,其湿态胶合强度为0.78 MPa,满足GB/T 9846.3-2004《胶合板第3部分:普通胶合板通用技术条件》中Ⅱ类胶合板的要求。     

豆胶的热反应特性及胶合特性分析

大豆蛋白胶因其可再生、可降解和环保性而受到广泛关注。豆胶的热反应特性和胶合特性研究结果显示:以20℃/min速率升温时,豆胶胶液在157℃时完全固化,在173℃开始降解;胶合板的胶合强度与涂胶量呈线性正相关。按热压温度160℃、热压时间80s/mm、压力1.6MPa、双面涂胶量450g/m2的工艺制备豆胶胶合板,其湿态胶合强度为0.78 MPa,满足GB/T 9846.3-2004《胶合板第3部分:普通胶合板通用技术条件》中Ⅱ类胶合板的要求。     

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.