漆酶-介体系统处理麦草化学浆全无氯漂白性能的研究

采用漆酶－介体系统对麦草化学浆进行预处理，研究了几种全无氯漂白（TCF漂白）[氧碱脱木质素配合两段过氧化氢漂白（OEPP），两段过氧化氢漂白（QPP）和过乙酸配合一段过氧化氢漂白(PaP)]对漆酶处理后纸浆漂白性能的作用，结果表明，麦草浆经过漆酶预处理后，白度上升了12．9个白度单位（%,ISO)，漆酶处理浆氧碱脱木质素配合过氧化氢漂白后比原浆在相同条件下漂白后白度高14个白度单位以上，经两段过氧化氢漂白后白度比原浆在相同条件下（过氧化氢用量4％）漂白后白度高18．3个白度单位，经过乙酸过氧化氢漂白后比原浆在相同条件下漂白后白度高8．1个白度单位。漆酶处理浆漂白后强度比原浆漂白后的低，但是其白度高，如漂至相同的白度可以节约大量漂剂，有利于改善浆的质量，降低漂白废水的污染负荷。     

有机酸生物炼制玉米秸秆皮浆短流程ECF漂白特性

为寻求合理白度、节省资源、节能减排的漂白途径,研究了有机酸玉米秸秆皮生物炼制浆(OABCSRP)的短流程碱处理-二氧化氯-二氧化氯(ED1D2)无元素氯(ECF)漂白特性。结果表明:碱处理对OABCSRP具有良好的脱木质素选择性,是后续二氧化氯(D)漂白的重要基础,在浆浓10.0%(质量分数)、温度70℃、时间1.5 h和用碱量4.0%的条件下碱处理,可获得率为95.4%、脱木质素率23.5%、黏度115 mPa.s、白度44.2%(ISO)的纸浆;在碱处理过程中浆料中木质素和碳水化合物中的酯键发生了水解;ECF短流程ED1D2在4.0%NaOH及总ClO2用量3.6%条件下,经ED1D2漂白后,可获积累得率为88.0%、黏度124 mPa.s、白度74.7%(ISO)的优良纸浆。     

麦草氧碱法纸浆压力/温度过氧化氢漂白

麦草氧碱法纸浆经压力/温度H2O2(Ppt)漂白时,纸浆的卡伯值随H2O2用量和氧压的提高而下降,卡伯值从17.3下降至2.38,下降幅度达86.2 %,表明Ppt漂白时,脱木质素效果明显.若采用氧脱木质素 -鳌合处理 -压力温度H2O2漂白(OQPpt)和氧脱木质素 -酸处理 -压力温度H2O2(OAPpt)漂程,当H2O2用量为原料质量的3 %～4 %时,均可将麦草氧碱纸浆漂至白度80 %(SBD,以下同)左右,而采用OAPpt漂白比OQPpt漂白的纸浆的白度高2.0 %左右,且聚合度达到1 038左右.     

麦草化学机械制浆预处理方法研究

使用麦草原料制取漂白化学机械浆,为了后续多段漂白能够获得高白度的纸浆,研究了3种不同的化学药品用于预浸渍阶段对未漂白浆的光学和物理性能的影响,包括成浆白度、成浆强度指标、纤维筛分级分,并比较了磨浆的比能耗和废水污染负荷.研究结果表明,与碱性过氧化氢(2.0%NaOH、1.5%H2O2、0.4%DTPA)处理(P工艺)磨浆相比亚硫酸钠(2.0%Na2SO3、2.0%Na2CO3、0.4%DTPA)预处理(S工艺)磨浆比能耗降低了33%,果胶酶(10IU/g以绝干浆计)/碱性过氧化氢(2.0%NaOH、1.5%H2O2、0.4%DTPA)预处理(Pe/P工艺)也可以降低磨浆比能耗10%,P工艺预处理与S工艺预处理均能提高成浆白度,Pe/P工艺预处理成浆呈现暗红色;P工艺预处理成浆物理强度高于其他两种浆;S工艺预处理磨浆段废水化学耗氧量(COD)发生量较高,达到84.09kg/t(以绝干浆计).     

相思木EMCC硫酸盐浆氧脱木质素前后酶处理的影响研究

研究了酶处理对相思木EMCC(延伸改良连续蒸煮)硫酸盐浆(KP浆)氧脱木质素效果的影响。结果表明,由白腐菌直接合成的漆酶/木聚糖酶体系(LXS)预处理相思木EMCC硫酸盐浆的的适宜酶用量为7 IU/g;LXS预处理后浆料氧脱木质素的适宜反应时间、最高反应温度及用碱量分别为60 min、100℃和2.5%;利用LXS进行氧脱木质素后处理的适宜反应时间及酶用量分别为2 h和5 IU/g。SEM观察到经过酶处理后纤维表面及横切面出现大量的裂隙及孔隙,其中以酶后处理最为明显,为后续漂白中化学药品的渗透和漂白降解产物的溶出创造条件。     

DMD的活化预处理及其全无氯漂序的研究

研究了桉木硫酸盐浆对氧脱木质素段和过氧化氢漂段的活化作用以及ＤＭＤ用量对氧段和过氧化氢段浆性能的影响,使经ＭＯＱＭＰ多段漂白的纸浆最终白度达８０％以上,纸浆粘度满足要求,可以实现桉木硫酸盐浆的全无氯漂白。     

三倍体毛白杨低硬度NaOH-AQ浆全无氯漂白的研究

通过实验探讨了三倍体毛白杨低硬度NaOH-AQ浆(卡伯值13.5,粘度851 mL/g,白度37%,ISO)H2O2强化氧脱木质素(QOP)的工艺条件,在此基础上提出了QOP、QP全无氯漂白的漂序,此漂序可以把该纸浆漂至82.0%(ISO),粘度保持在716 mL/g,漂后纸浆得率91.78%,而且该漂序可操作性强,是一种适合低硬度NaOH-AQ浆的全无氯漂白新工艺.     

二氧化氯漂白技术用于提高竹浆粕白度的研究

探讨了竹浆粕生产过程中二氧化氯漂白(D1、D2段)的重要性和必要性,D1段和D2段分别研究了ClO2用量、NaOH用量、温度、时间4个因素及ClO2用量单因素对二氧化氯漂白效果的影响,包括α-纤维素、聚戊糖、白度、卡伯值、黏度、灰分等性能,其中D1段分析了白度提高与浆粕α-纤维素、聚戊糖及灰分的关系。结果表明,D1段最优工艺条件为:ClO2用量1.52%且NaOH用量0.76%(NaOH与ClO2质量比1∶2),温度75℃,时间120 min,浆质量分数10%。经D1段处理后,竹浆白度提高率达到了78.8%,黏度下降率仅为19.55%,漂白选择性高。在D1段漂白工艺的基础上,确定D2段的ClO2用量0.8%,且漂白时间120 min,漂白温度75℃,浆质量分数10%。浆料白度增加的过程中,一定程度上提高了α-纤维素含量同时降低了聚戊糖及灰分等杂质的含量,达到了调整竹浆粕质量指标和提高反应性能的目的。经含有两段二氧化氯漂白的无元素氯漂白流程处理后,竹浆粕最终白度达到了88.2%(ISO)。     

碱性木聚糖酶在中小径竹KP浆漂白中的应用

探讨碱性木聚糖酶用于中小径竹KP浆漂白预处理的最佳工艺条件及碱性木聚糖酶预处理对中小径竹KP浆ECF漂白的影响.结果表明,碱性木聚糖酶Unikfect 100处理浆的最佳工艺为:浆浓度4%,pH值9.0,温度65℃,时间20 min,酶用量15.0×10-7 mol·s-1g-1浆;对ECF漂白的影响为:O-X-D1-EOP-D2漂序的漂白效果优于O-D/C-EOP-D2,在白度相近的情况下,纸浆的粘度及物理强度较高.     

甲脒亚磺酸漂白废旧新闻纸脱墨浆

采用甲脒亚磺酸(FAS)对废旧新闻纸脱墨浆进行了单段漂白实验,探讨了FAS用量、NaOH和FAS用量比、浆浓、漂白温度和时间对纸浆漂白的影响。结果表明:废旧新闻纸脱墨浆采用单段FAS漂白,其最佳工艺条件为FAS用量0.6%,NaOH用量0.3%,浆浓5%,温度70℃,时间60 min,纸浆白度可达57.9%SBD。     

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.