清水竹笋罐头加工工艺探索

本文是课题总结。该课题从1983年起至1986年止。协作单位宁波罐头厂。经过小型试验,扩大的加工工艺试验和生产性加工工艺试验,其结果为: Ⅰ.分析了毛竹笋罐头的白色沉淀物的主要成分—酪氨酸含量为90％。Ⅱ.测定了毛竹笋不同时期酪氨酸含量的变化。Ⅲ.测定了毛竹笋不同部位的酪氨酸含量。Ⅳ.分析了毛竹笋罐头汤汁在贮存期酪氨酸含量的变化曲线。了解到形成白色沉淀的原因以及此时酪氨酸的相应浓度范围。Ⅴ.研究出了毛竹笋罐头的最佳予煮和漂洗工艺:加柠檬酸(0.07％)预煮1.5小时,漂洗12小时。产品质量全部超过原工艺。预煮能源和漂洗用水大大节约。新工艺深受厂方欢迎。     

不同预处理与纳滤膜组合工艺的研究综述

阐述了常规水处理工艺、深度处理工艺和超滤与纳滤膜工艺组合的特点,对近年来有关于不同预处理工艺+纳滤组合工艺的研究进行了总结。从水质保证效果、膜污染及运行成本等方面对几种常见的纳滤膜组合工艺进行了分析和总结。以供参考。     

多点循环A~2/O工艺处理工业园区污水的试验研究

本研究针对松花江宾西工业园区所处的寒冷地区气候特点,以多点循环A2/O工艺为研究对象,在不同温度条件下对试验工艺有机污染物去除效果进行分析,研究成果可望对污水厂在低温下的运行给出指导,进而保护冰封期松花江的水质。研究发现,随着温度的降低,试验工艺具有较高的稳定性,对COD、NH3-N及TN及TP的去除效果下降幅度均较小,在低至14℃时仍能达到国家一级A排放标准。     

红松适宜采种期的研究

文章对红松不同采种期进行研究,分析不同时期的种籽质量指标,对红松不同采种期进行了试验,提出了红松采种期的适宜时间。     

降低中密度纤维板预固化层技术探讨

为从理论上研究中密度纤维板预固化层产生的技术成因,通过施胶量、温度、含水率、压机闭合速度等物理方法试验,寻找影响中密度纤维板预固化层的主要原因,探索降低预固化层的工艺路线,并优选工艺参数;通过改变调胶工艺、添加助剂等试验,寻找降低预固化层的合理助剂,确定添加量和添加工艺,并运用到实际生产中.     

桉木循环强化预水解过程中有机酸变化规律

以桉木为原料,将桉木经热水预水解后,将预水解液按不同比例循环回用于桉木的预水解,在桉木粉(8 g)与不同水解介质6∶1(m L∶g)的条件下,探讨了循环强化预水解过程中,主要的有机酸(乙酸、甲酸和乙酰丙酸)及总糖的生成和变化情况。结果表明:反应温度190℃,在不同保温时间下,循环强化预水解液中的甲酸和乙酰丙酸浓度随着保温时间的延长而增加,而乙酸浓度则先增加,后期虽有波动,但是稳定在较高水平,而总糖则呈现先增加后下降的趋势;保温时间60 min,在不同预水解温度下,循环强化预水解液中的有机酸和总糖质量浓度随着预水解温度的升高呈现增加的趋势;在上述两种效应研究中,循环比的增大均对循环强化预水解液中的有机酸质量浓度提升有正面效应。循环强化预水解工艺的水解过程自产酸得以富集,利于其资源化利用,而自产酸具有催化水解进程的功能。     

高酸价酸化油制备生物柴油研究

以酸化油为原料两步法制备生物柴油,以对甲苯磺酸作为催化剂,采用分段反应的预酯化工艺先将酸化油脂中的脂肪酸转变为脂肪酸甲酯(FAME),然后再碱催化酯交换反应得到生物柴油.考察了甲醇与脂肪酸物质的量之比(醇酸比)等不同条件对预酯化反应的影响.通过正交试验得到最佳的预酯化反应条件并研究了油脂酸价对碱催化酯交换的影响.试验结果表明,各因素对酯化反应影响大小依次为反应温度、催化剂用量、醇酸比和反应时间,预酯化最优化的工艺条件为:醇酸比10∶1,催化剂用量3%,反应时间150min,反应温度70℃,通过分段反应的预酯化工艺,反应时间缩短了1h,催化剂回收率达到90%以上.进行碱催化酯交换的油脂要求酸价不能大于4mg/g.     

高浓度茶多酚废水工程升级改造实例

指出了高浓度茶多酚废水其水质特点是有机物浓度高、难于生物降解 ,原工程实例处理效果不达预期 ,其UASB、接触氧化池等工艺无法正常运行 ,出水水质不达标.对此进行了废水工程升级改造 ,介绍了混凝沉淀+微电解+芬顿、水解酸化池、IC反应器、气浮池等在工程中的实际应用 ,详细阐述了工艺原理、主要工艺参数.改造后运行结果表明 :预处理效果显著 ,装置运行稳定 ,操作运行简便 ,对水质波动适应能力强 ,出水水质中COD、SS、色度等指标均达到枟污水综合排放标准枠(GB8978-1996)中二级排放标准.     

水处理与水质稳定技术

水处理与水质稳定技术该项成果包括新型净水剂聚合硫酸铁，工业用水浊循环系统中的水质稳定技术及高效气浮成套设备等三项技术。聚合硫酸铁是一种高效的铁系无机高分子混凝剂，具有絮凝效果好，颗粒沉降快，ＰＨ值适应范围广，对设备腐蚀性小，脱臭性能好等优点。现有液、...     

杉木苗圃化学除草技术

介绍了在杉木育苗播种前，播后苗前，幼苗形成期，苗木初生期、速生期等不同时期进行化学除草应选用的不同除草剂和相应的剂量及施药时应注意的事项。     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

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。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.