造纸涂料用丙烯酸增稠剂的合成

通过乳液聚合合成了造纸涂料用的增稠剂，最佳条件是：所用乳化剂以阴离子与非离子复合为优，阴离子与非离子的比例为1．5：1，乳化剂的质量用量为1．5％；所用单体中疏水单体丙烯酸乙酯占70．6％、亲水单体丙烯酸占29．4％、交联剂占O．4％～O．6％；引发剂的质量用量为O．15％～O．24％(单体量的)；羟甲基丙烯酰胺的质量用量为1％～1．4％；乳液固含量以28％～30％为宜；乳液的pH值达4时乳液稳定。     

木质素磺酸盐与丙烯酸类单体的接枝共聚研究

研究了木质素磺酸盐粗产品与丙烯酸类单体的接枝共聚反应，对其反应机理进行了评述，并采用红外光谱分析证实了聚合反应的发生。与现有的对纯化木质素磺酸盐的研究结果不同，粗产品的接枝共聚反应可以单纯由过氧化氢引发，原因可能是粗产品中含有的还原性物质起到了亚铁离子的作用。研究表明，合适的引发剂用量应该是木质素磺酸盐干重的1．5％～2．0％，当反应体系中引发剂用量充分时，反应温度和时间对产物粘度的影响不明显。产物的粘度随丙烯酸类单体用量的增加而提高，在相同单体用量下，丙烯酰胺改性产物的粘度高于丙烯酸改性产物，原因是丙烯酰胺聚合物上酰胺基的亲水性比丙烯酸聚合物上羧酸基的亲水性低。     

丙烯酰胺/马来酸酐共聚高吸水树脂PAMMAH研究

以丙烯酰胺(AM)和马来酸酐(MAH)为单体M,N,N’-亚甲基双丙烯酰胺为交联剂C,过硫酸钾为引发剂I,在一定中和度下采用溶液聚合法,合成了丙烯酰胺／马来酸酐共聚高吸水树脂PAMMAH,并进行了吸液性能研究,得到最优合成条件为:R(n (AM):n(MAH))=5:1,WM=25％,WC=0．02％,WI=0．4％,N=130％,30℃(4 h)→60℃(4 h)→80℃(3 h)．最大吸液性能为:吸蒸馏水倍率Qw=3 193 g／s,吸0．9％NaCl盐水倍率Qs=213 g／g．PAMMAH树脂的吸蒸馏水倍率、吸0．9％NaCl盐水倍率与吸液时间的关系为:Qw=1 174．15 t0．2511和Qs=68．86 t0.2127．     

萜烯－马来酸酐不饱和聚酯树脂的合成及其性能研究

以优级松节油为原料，合成萜烯－马来酸酐加成物（简称ＴＭ）．再以ＴＭ、马来酸酐、二元醇等为基料，合成了几种不饱和聚酯树脂（ＴＭ－ＵＰ树脂）．讨论了不同配方及合成工艺与树脂产品性能的关系，并对其物化性能、树脂浇铸体力学性能及耐腐蚀性能等进行了测试，从中选出了几种综合性能较好、工艺较简单、成本较低的ＴＭＡ－ＵＰ树脂配方．通过比较得知制得的ＴＭ－ＵＰ树脂性能达到或超过通用型商品ＵＰ树脂，完全可代替通用型商品ＵＰ树脂应用．     

用磷钼酸催化合成马来海松酸反应的研究

以杂多酸磷钼酸为催化剂合成了马来海松酸。号察了催化剂用量、溶剂、反应时间及原料配比等对双烯加成反应的影响。实验结果表明．松香与马来酸酐摩尔比为1．7：1．催化剂质量分数为2．0%，甲苯作溶剂，反应时间4h，反应得率可达78．9％。     

复合型淀粉高吸水性树脂在不同介质中的吸水能力研究

以亚硫酸氢钠和过硫酸铵组成的氧化还原引发剂，N，N`-亚甲基二丙烯酰胺为交联剂，使淀粉三元接枝丙烯酸和丙烯酰胺，在含有粘土的悬浮液中反应，制得淀粉复合型高吸水性树脂。在本实验条件下获得最优反应条件为：反应温度为70℃，引发剂含量为单体0．3％、丙烯酰胺含量为丙烯酸40％、丙烯酸中和度为90％。发现树脂在一元醇中吸收能力小于多元醇，并且分子越大，吸收能力越低。而且在醇中的吸收能力明显低于在去离子水中的吸水能力。在中性范围内，树脂具有最大的吸水能力。而在酸性或碱性条件下，树脂的吸水能力明显减小。     

聚醋酸乙烯酯乳液的改性研究

从聚醋酸乙烯酯的分子结构、性质及其乳液的最低成膜温度出发，以丙烯酸类单体为改性单体，采用均匀设计法来设计合成共聚型乳白胶的配方，对乳液的胶合性能进行检测，对胶合强度进行回归分析，从而得到具有一定使用价值的工艺配方。研究结果表明：当聚乙烯醇的浓度为8．5％、醋酸乙烯与改性单体的比例为75：25、官能性单体的比例为2％、引发剂的比例为2．5％、乳化剂的比例为4％时，其玻璃化温度Tg=2．94℃，干态剪切强度达13MPa以上，木破率达90％以上，湿态剪切强度达4MPa以上，而且胶层的韧性和耐水性得到明显改善。     

冰片烯-二氧化硫聚砜树脂的合成及表征

以α-蒎烯为原料合成冰片烯.以冰片烯(BE)、二氧化硫(SO2)为单体,采用自由基聚合方法合成了冰片烯-二氧化硫聚砜树脂(BE-SO2),用同样的方法分别以冰片烯(BE)、二氧化硫(SO2)、马来酸酐为单体和以冰片烯(BE)、二氧化硫(SO2)、苯乙烯(St)为单体,合成冰片烯-二氧化硫-马来酸酐(BE-SO2-Ma)...     

双戊烯合成萜马加成物反应的动力学及主产物结构的研究

以稀土金属氧化物为催化剂，催化工业双民顺丁烯二酸酐连续进行异构／Ｄｉｅｌｓ－Ａｌｄｅｒ反应，合成出萜烯／马来酸酐加成物；用气相色谱法跟踪研究了反应的进程，并模拟了反应反动力学方程，鉴定了主产物的结构，结果表明动力学方程的拟合精度好，平均相对误差小于２．５％；产物中绝大部分是正常的双烯加成物。     

双组分有机硅改性丙烯酸聚氨酯水性木器涂料的研制

探讨了有机硅氧烷的种类、酸值、羟值、中和度和玻璃化温度对水性有机硅丙烯酸羟基树脂的外观、粘度、水溶性、分子质量大小、与固化剂的相容性和所配置清漆涂膜性能的影响。研究结果表明，使用含水解阻碍性官能团的有机硅氧烷单体、酸值在35～50mgKOH／g，羟基含量为3．5％左右，中和度约为85％，玻璃化转变温度为0～15℃，合成的树脂与固化剂配漆所得涂膜性能优异。     

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.