改性毛杨梅栲胶减水分散性能研究

研究磺化改性毛杨梅栲胶对水泥的减水分散性能.结果表明:当水泥中栲胶和改性栲胶的掺加质量分数为0.5%,混凝土减水率分别为7.1%和13.1%,掺改性栲胶的水泥净浆初凝和终凝时间比掺栲胶的净浆分别缩短3 h 15 min和8 h 50 min;栲胶磺化改性后表面活性下降,基本失去起泡能力;栲胶和改性栲胶质量浓度为2.0 g·L-1时, 在水泥颗粒表面的平均吸附量分别为7.39和5.91 mg·g-1;栲胶和改性栲胶质量浓度均为1.0 g·L-1时,在水泥颗粒表面的ξ-电位分别为-22.13和-25.53 mV.故栲胶磺化改性后对水泥的减水分散能力增强.     

木质素磺酸钠与聚羧酸减水剂复配研究

通过氧化、磺甲基化改性造纸黑液制取木质素磺酸钠(SLS),磺化度为1.023 7 mmol/L,重均相对分子质量(M_w)为26 320;将SLS与聚羧酸高效减水剂(PCE)按一定比例复配制备复合减水剂,SLS质量分数为10%、20%、30%和40%时,分别制得复合减水剂BPCE1~BPCE4。复合减水剂对水泥颗粒表面吸附层厚度和水泥浆Zeta电位分析表明:吸附层厚度随SLS质量分数增加而增加,水泥浆Zeta电位在SLS质量分数为20%时显示出绝对值最大。采用复配木质素磺酸钠的复合聚羧酸减水剂制备混凝土,复合减水剂掺量0.18%、SLS总掺量1%。通过净浆流动度、胶砂流动度、泌水率、减水率、混凝土抗压强度等指标对复合减水剂进行综合性能分析。结果表明:含20%SLS的复合聚羧酸减水剂BPCE2减水剂综合性能最佳。     

毛杨梅栲胶重度亚硫酸化改性与应用研究

在高温和铝化合物存在下，对毛杨梅（Myrica esculenta)栲胶进行重度亚硫酸化改性，将改性栲胶用作皮革中和剂，研究了影响改性产物性质的一些参数，如缓冲性，中和性能等。得出最佳改性方案，其质量配比为：毛杨梅栲胶100份，NaHSO3 30 份，Na2SO3 36份，含铝化合物1份，在129摄氏度，165kPa下反应10h得到改性栲胶产物。改性栲胶水溶性良好，5％溶液pH值为7．15，10％溶液pH值为7．0，分析表明，其宁含量在20％到30％之间，符合皮革中和复鞣剂的要求，缓冲性实验表明，适量未反应的亚硫酸盐能与改性单宁组成缓冲体系，在pH值3．5－5．5之间具有良好的缓冲性，鞣性实验表明，经亚硫酸盐处理后，毛杨梅栲胶的鞣性显著下降，收敛性缓和，渗透迅速，用量以削匀蓝革计3％－5％为佳，视铬复鞣后pH值而定，1％的用量约可使pH值提高0．3，由于改性栲胶还保留着适当的鞣性和填充性，因此它具有中和与复鞣的双重作用。     

利用栲胶废渣生产水泥塑化剂

在批林批孔运动的推动下,我厂经过一个多月的时间建成塑化剂生产车间。它的主要用途是在混凝土浇筑施工中,减少水的表面张力,以利于机械施工,同时还可节约水泥用量,提高浇筑质量。生产这种塑化剂,设备简单,投资少,可土法上马,充分利用栲胶废渣(红根、橡椀)和栲胶生产过程中的溢漏排污的废水,同时有力地减少了废渣废水对环境河流水系的污染。生产这种液体水泥塑化剂的工艺是:废渣红根或橡椀以绝干重量计,1份料加废水5.5～6份,加固体烧碱(NaOH)约20%,在常压下煮沸1～3小时后放入中和池,约加25%的盐酸(工业用)中和,静置24小时即可供使用。     

去甲基木质素环氧树脂合成及其改性大豆基胶黏剂的性能北大核心

以工业碱木质素为原料,通过去甲基化处理提高木质素酚羟基含量,然后在碱性条件下与环氧氯丙烷反应合成去甲基木质素环氧树脂(DLEP),用于改性大豆基胶黏剂。去甲基化结果表明,木质素酚羟基含量由1.97 mmol/g提升至2.98 mmol/g,与未处理木质素相比,提高约51%。环氧值滴定结果显示,DLEP的环氧值达到0.297 mol/100 g,比直接用木质素合成环氧树脂(LEP)的环氧值提高近29%。红外光谱(FT-IR)和扫描电镜(SEM)表征显示,木质素甲氧基脱除生成了新的酚羟基;DLEP成功枝接了环氧基团;DLEP中的环氧基与大豆蛋白中氨基、羧基及羟基反应,形成致密的交联结构。当DLEP质量分数为4%时,胶黏剂的湿胶合强度达1.34 MPa,比纯大豆基胶黏剂高119.6%,满足GB/T 9846—2015中Ⅱ类板的要求。     

微波辅助木质素脱甲基化改性及结构表征

为提高木质素的反应活性,采用微波辅助加热方式,在HBr/十六烷基三正丁基溴化磷(HBr/TBHDPB)体系下对木质素进行脱甲基化改性。考察了HBr用量、反应温度、反应时间和催化剂用量对木质素改性反应的影响。通过紫外光谱(UV)、核磁共振氢谱(1H NMR)、傅里叶变换红外光谱(FT-IR)、凝胶渗透色谱(GPC)和元素分析等手段研究了木质素改性前后的官能团及分子质量变化,并由羟甲基化反应和曼尼希反应分析了木质素改性前后的活性变化。结果表明:木质素在微波辅助加热条件下,HBr用量为20 mmol/g,催化剂TBHDPB用量为木质素质量的2%,95℃反应1 h,制备的改性木质素含酚羟基为4.95%,相比原料木质素提高了32.71%,甲氧基为6.11%,相比原料木质素降低了20.44%。与甲醛反应的活性提高了18.15%,胺基侧链增加了7.54%。UV、1H NMR和FT-IR分析也表明,改性木质素的酚羟基含量增加,甲氧基含量降低。     

低游离甲醛羟甲基化木质素磺酸盐-酚醛复合胶黏剂研究

以工业木质素为原料,采用羟甲基化反应提高木质素反应活性,确定了羟甲基化反应木质素和催化剂的最佳配比:木质素与甲醛质量比为3:1、催化剂用量为0.25%(以木质素原料计).并用FT-IR和13C NMR对羟甲基化反应结果进行了分析.通过羟甲基化木质素磺酸盐(HLF)与酚醛树脂(PF)共混制得木质素酚醛树脂(LPF)胶黏剂.实验结果表明,该胶具有制备工艺简单、游离甲醛低的特点,用HLF替代40%的PF时,其胶合强度达到国家Ⅰ类胶合板的要求.     

改性木材硫酸盐木质素制备染料分散剂的研究

以松木硫酸盐木质素为原料合成染料分散剂。硫酸盐木质素经亚硫酸盐磺化或亚硫酸盐一甲醛磺甲基化后，再用环氧氯丙烷将部分酚羟基封闭，同时使木质素分子间交联，得到改性木质素染料分散剂。研究了磺化时间、磺化剂用量等因素对木质素磺化度、木质素染料分散剂热稳定性及分散性的影响。确定了适宜的反应条件，以每克木质素为基准，磺化反应：Na2SO3用量1．3mmol，反应时间3h，反应温度160℃；磺甲基化反应：Na2SO3用量1．3mmol，甲醛／亚硫酸钠摩尔比为O．8：1，反应时间3h，反应温度140℃。     

二元端乙烯基型松香衍生物的微波辅助制备及表征

以丙烯酸改性松香酸钠和氯丙烯为原料,十六烷基三甲基溴化铵为催化剂,对苯二酚为阻聚剂(用量为丙烯酸改性松香钠质量的0.2%),N,N-二甲基甲酰胺为溶剂(用量为丙烯酸改性松香钠质量的3倍),在微波辅助条件下,探讨了工艺条件对二元端乙烯基型松香衍生物丙烯酸改性松香烯丙酯得率的影响,确定了最佳工艺条件为:微波功率400 W,反应时间100 min,催化剂用量4%,物料配比n(氯丙烯)∶n(丙烯酸改性松香钠)2∶1,反应温度50℃,在此条件下产物得率高达92.2%。采用GC、GC-MS和FT-IR等技术表征了反应产物的结构,结果表明合成产物结构与目标产物结构一致。     

新型脂肪族高效水泥减水剂技术

随着建筑业水利工程的迅速发展,对混凝土各方面的性能不断提出了新的要求。减水剂是混凝土中用量最大的外加剂品种,按其减水效果可分为普通减水剂和高效减水剂。随着工程质量要求的提高,高效减水剂的发展越来越受到重视。水泥减水剂的作用,就是加入水泥减水剂后可明显减少拌和水泥混凝土时所加入的水量,同时大大提高水泥混凝土浆料的流动性能和水泥混凝土的强度,从而提高工程的质量。我国在20世纪80年代开始使用水泥减水剂,但由于普通减水剂的天然缺陷、萘系减水剂的价格居高不下、伪劣产品等因素的     

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.