交联羧甲基魔芋葡甘聚糖微球的制备与表征

采用魔芋葡甘聚糖颗粒(KGG)在醇水溶液中合成了羧甲基魔芋葡甘聚糖微球(CMKGG)，进而合成了交联羧甲基魔芋葡甘聚糖微球(CCMKGG)，讨论了合成过程中的影响因素。通过应用正交设计的方法确定了碱用量为魔芋葡甘聚糖(KGM)量的20％，氯乙酸用量为KGM量的10倍，温度55℃，反应8h制得的羧甲基魔芋葡甘聚糖的羧甲基程度较好。交联产物具有较好的交换容量。红外光谱、光学显微镜和扫描电镜的结果表明，该颗粒为蜂窝状多孔微球，粒度均匀。经测试其阳离子交换容量为0．9538mmol／g，不溶于水，对酸、碱稳定。     

酚醛树脂原料配比对麻毡板性能的影响

研究了酚醛树脂的不同原料配比对麻毡板性能的影响。结果表明：1)麻毡板的内结合强度随着F／P摩尔比的增加而增加，随尿素用量的增加而降低；在一定范围内，碱用量、甲基葡萄糖甙(TD)的用量对其影响不大。2)麻毡板的吸水厚度膨胀率随着F／P摩尔比的增加而减少，随着碱、尿素、甲基葡萄糖甙用量的增加而增加。适宜的原料配比为：尿素量在树脂总量的4％，F／P摩尔比为2．0，NaOH／P摩尔比为0．06，甲基葡萄糖甙在树脂总量的4％。     

微波辐射没下食子酸异丁酯的合成

采用微波辐射技术，以对甲苯磺酸（PTSA）为催化剂，没食子酸和异丁醇为原料，直接酯化合成没食子酸异丁酯。研究了微波功率、辐射时间、催化剂的用量、酸醇摩尔比等因素对于酯化反应产率的影响，并对产品进行了分析和鉴定。通过正交试验探讨出最佳的反应条件为：没食子酸与异丁醇摩尔比1：17，没食子酸与催化剂摩尔比1：0．05，微波功率510W（没食子酸用量10．94g），辐射时间60min，平均酯化产率为86．3％。     

苯甲酸对魔芋精粉化学改性的初步研究

经用苯甲酸对魔芋葡甘聚糖进行化学改性试验，所得的改性较好条件为：苯甲酸与魔芋精粉的用量比（Ｗ／Ｗ）为０６∶１００；反应温度４５℃；反应时间３ｈ；ｐＨ值为４～５；烘干时间为６ｈ；干燥温度为５０℃。实验结果表明：魔芋葡甘聚糖经苯甲酸改性后，具有与用其他方法改性制品相似的性质，其成膜性、稳定性与未改性者相比，均有明显的改善，粘度提高了２倍多，且具有相当的抑菌效果。通过对改性魔芋葡甘聚糖进行保鲜试验，结果表明改性后的魔芋葡甘聚糖保鲜效果较好，可作为保鲜剂。     

苯甲酸对魔芋精粉化学改性的初步研究

经用苯甲酸对魔芋葡甘糖进行化学改性试验,所得的改性较条件为：苯甲酸与魔芋精粉的用量比（Ｗ／Ｗ）为０．６：１０．０;反应温度４５℃;反应时间３ｈ;ｐＨ值为４－５;烘干时间为６ｈ;干燥温度为５０℃。实验结果表明：魔芋葡甘聚糖经苯甲酸改性后,具有与用其他方法改性制品相似的性质,     

羟基保护法合成松香酰二乙醇胺及其表面活性初探

先用二氢吡喃保护二乙醇胺的羟基，与松香酸甲酯(RAME)反应制得松香酰二乙醇胺二(四氢吡喃醚)后，再经羟基解保护后制备松香酰二乙醇胺(RDEA)。二次回归正交试验优化的合成条件为：松香酸甲酯与二乙醇胺二(四氢吡喃醚)摩尔比1：1．6，反应温度93℃，反应时间4．4h，催化剂乙醇钠用量为二乙醇胺二(四氢吡喃醚)的2．5％，松香酰二乙醇胺得率为93．87％。性能测定表明，松香酰二乙醇胺的发泡能力及泡沫稳定性、乳化能力与十二烷基硫酸钠(K12)相当，临界胶束浓度较K12略大。松香甲酯化制备松香酸甲酯的最佳制备条件：松香与甲醇摩尔比1：3、反应时间1h、反应温度70℃、催化剂氢氧化钾用量为松香的2％，酯化率为95．50％。     

重金属离子捕集剂——不溶性木屑黄原酸酯(IXS)

中国林业科学研究院林产化学工业研究所苏才元、何友仁同志研究了以木屑为原料,利用木屑中的纤维素的C_2、C_3的仲醇基和C_6的伯醇基,在适宜条件下化合成醚或酯等衍生物。制备过程如下: 木屑→NaOH碱渍→CS_2黄原酸化→稳定化→过滤洗涤→产品IXS。通过实验确定了NaOH和CS_2的最适用量;当100克木屑用20％NaOH和30毫升的CS_2制备的IXS,其交换能力最大,此时交换当量能达到2.19毫克当量/克。 IXS用于水溶液中回收重金属离子,其交换容量如下:Ag~(+1)(90.60),Cd~(+2)(19.10),     

歧化松香胺Schiff碱-铜配合物催化苯乙烯氧化反应的研究

以H2O2为氧源，研究了歧化松香胺Schiff碱-铜配合物催化苯乙烯的氧化反应，探讨了溶剂种类、催化荆用量、氧化剂用量、反应温度及反应时间对催化氧化反应的影响。结果表明，催化氧化反应的较佳条件是：以1，4-二氧杂环己烷为溶剂，苯乙烯5.000g，催化剂Schiff碱-铜配合物用量为苯乙烯质量的0．5％，质量分数为30％的H20：15mL，80℃反应6h。苯乙烯转化率为93．3％，主产物苯甲醛的收率和选择性分别为66．8％和71．7％。     

响应面法优化钙基固体碱KF/CaO催化沉香籽油制备生物柴油

采用固体碱KF/Ca O催化沉香籽油进行酯交换反应制备生物柴油(脂肪酸甲酯),通过扫描电镜、X射线衍射和傅里叶红外的表征发现KF/Ca O呈多层片状结构,具有较大的比表面积(107±0.5)m~2/g,催化活性主要成分为KCa F3,红外谱图验证了Ca—O—F晶格的存在。单因素试验对影响催化酯交换反应的各因素进行优化,得出较佳范围为:反应时间100 min、催化剂用量2.0%、醇油摩尔比8∶1、反应温度79℃。单因素试验基础上采用Design-Expert软件Box-Behnken模块进行响应面试验条件优化,探讨了催化剂用量(A)、反应温度(B)、醇油摩尔比(C)、反应时间(D)4个因素及各因素间交互作用对转化率的影响,结果表明各因素一次项对转化率都呈高度显著水平,最佳条件为:反应时间107.2 min、催化剂用量2.02%、醇油摩尔比8.36∶1、反应温度79.14℃,所制备的生物柴油能够满足国标要求。     

魔芋葡苷聚糖/壳聚糖共混胶黏剂应用于胶合板的研究

以胶合强度为考察指标,进行魔芋葡苷聚糖/壳聚糖共混配比胶黏剂工艺的制备研究.试验结果表明,胶黏剂中各组分用量的较佳参数为:壳聚糖1%,魔芋葡苷聚糖1.5%,NaOH为1%.此配比制备的胶黏剂压制的胶合板,干状胶合强度最大;在壳聚糖1%,魔芋葡苷聚糖1.5%,NaOH为2%的配比时,胶合板的湿状胶合强度最大.     

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

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.     

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.     

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.     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.