以酶解渣为碳源制备木聚糖酶的研究

以里氏木霉（Tichoderma reesei)Rut C-30为产酶菌，低聚木糖制备过程中酶解渣为碳源可透导产生含低纤维素酶活（0.106IU/mL)的木聚糖酶（154.67IU/mL)，两种酶活的比值达1459，与粗木聚糖为碳源产木聚糖酶相比，木聚糖酶活提高了1.67倍，而纤维素酶活没有增加。此酶在50℃条件下酶解粗木聚糖和酶解渣时，pH值5时酶解效率最高，酶解产物通过HPLC分析，主要是木糖。该酶系的组成主要是外切-β-木糖苷酶。     

Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]     

Cost minimization through the use of taungya system in pulpwood plantation establishment

The costs and benefits of the use of three labour alternatives: direct permanent, direct casual and taungya labour in Gmelina arborea pulpwood plantation establishment in Nigeria were investigated. Results show that cost per hectare is lowest with taungya labour and highest with permanent labour with savings in cost of as much as 30% and 47% by taungya labour over casual and permanent labour respectively. The net present value per hectare of investment is highest when taungya labour is used and lowest and negative with permanent labour. Also, the internal rate of return of investment is highest with taungya labour and lowest with permanent labour. The net present values and internal rates of return for Gmelina plantations calculated for the three pulp and paper mills in Nigeria show the same trend in favour of taungya labour.     

硫酸盐草浆黑液制粉状活性炭的研究

本文探讨硫酸盐草浆纸厂黑液的治理和利用,提出用酸化法从黑液中沉析木素制取粉状活性炭。大约生产10t草浆可制取1t优质粉状活性炭。同时还含有占总碱量24%的Na_2S可回收。排出的废液即使不再经过处理,其污染程度也已大大降低。     

料慈竹不同年龄纤维形态的研究

就贵州省赤水市料慈竹（Ｂａｍｂｕｓａｄｉｓｔｅｇｕｓ）０～４ａ５个龄级的纤维形态进行显微观测和系统分析表明，其纤维长度为２．１３～２．６９ｍｍ（平均２．４５ｍｍ），纤维宽度为１３．４２～１５．０６μｍ（平均１４．０９μｍ），长宽比历８～１８５（平均１７４），壁厚２．５２～６．４６μｍ平均４．８６μｍ），腔径２．１５～８．３９μｍ（平均４．４１μｍ），壁腔比为０．６～６．１７（平均３．２４）。通过方差分析后表明，除纤维长度和宽度外，年龄对料慈竹纤维形态有一定影响，表现在纤维壁厚度上，从０～１ａ有增厚，１ａ后相对稳定，至４ａ时明显增厚；纤维腔径相反，从０～１ａ腔径减小，至４ａ时明显减小。     

洞庭湖滩地造林成活率的关键影响因子

用样行法对洞庭湖滩地新造速生丰产纸浆林的成活率进行调查,同时了解造林地连续4 a汛期的水文规律和海拔高程的演变过程,通过分析造林成活率与主要影响因子之间的关系,发现淹水时间为滩地造林的限制性因子,营造速生丰产林、一般用材林和短周期工业原料林时,造林地年淹水天数依次不能超过19、35和62 d;苗木等级对造林成活率有重大影响,特级苗、Ⅰ级苗、Ⅱ级苗、Ⅲ级苗的平均成活率在海拔低于32 m的造林地上分别为68.8%、49.3%、18.7%、2.4%,在海拔超过32 m的造林地上分别为98.8%、79.6%、36.4%、14.7%;采用开沟抬垄整地可减轻涝渍胁迫,从而大幅度提高造林成活率.     

漆酶处理对未漂硫酸盐浆抗张强度和纤维表面的影响

探讨了漆酶处理对未漂硫酸盐浆抗张强度的影响,研究了漆酶处理的主要工艺参数对纸页湿抗张强度的影响;并采用扫描电镜(SEM)对漆酶处理前后纤维表面微细结构的变化进行了研究。结果表明,漆酶可以改善纸浆的湿抗张强度,但对于抗张强度不起作用;提高纸浆湿强度的最佳酶促反应条件为:酶用量16U(以每克绝干浆计),温度45℃,pH值4.5,处理时间2h。扫描电镜分析表明,漆酶处理使得纤维表面变得粗糙,纤维之间产生了黏结性,湿强度得以提高。     

Liquefaction and product identification of main chemical compositions of wood in phenol

To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose.     

Carbon and nitrogen dynamics under windrowed residues during the establishment phase of a second-rotation hoop pine plantation in subtropical Australia

The dynamics of carbon (C) and nitrogen (N), derived from the decomposition of windrowed harvest residues, was examined in the establishment phase of a second rotation (2R) hoop pine (Araucaria cunninghamii Aiton ex A. Cunn) plantation in subtropical Queensland, Australia. Following harvesting and site preparation, when residues were formed into windrows, in situ N mineralisation was measured in positions along the three tree-planting rows formed between the windrows. The position above the windrow had a higher nitrification rate than the other positions, averaging about 18 kg N ha⁻¹/month compared with 12 and 9 Kg N ha⁻¹ for the positions between and below the windrow positions, respectively. This position also had consistently greater soil moisture.

Macroplots were formed extending 5 m above and 10 m below a windrow. Windrowed residues within the macroplots were replaced by ¹⁵N-labelled material comprising hoop pine foliage, branch and stem. Hoop pine trees were planted within each macroplot with foliar samples taken at 12 and 24 months. Differences in foliar ¹⁵N enrichment between positions within macroplots were <1‰. Soil samples were taken from positions along the macroplots at 6-monthly intervals. Samples revealed an initial release of labile C and N but soil δ¹⁵N showed that residue-derived N was largely immobilised within the windrows for the 30-month sampling period. Whilst the use of windrows may act as a barrier to the down-slope movement of water, the residue N within the windrows may not be available to the trees of the following rotation for a considerable period following planting. Trees closest to the windrows may be able to introduce roots under the windrows thereby gaining access to the available N, but trees in the central tree planting row are unlikely to derive any significant benefit from the decomposition of windrowed residues.     

超高效液相色谱法测定吡蚜酮在棉花和土壤中的残留

建立了超高效液相色谱-亲水色谱柱测定吡蚜酮在棉花和土壤中残留量的分析方法。样本在弱碱条件下采用分散固相萃取(QuEChERS)法进行前处理。结果表明:吡蚜酮在棉叶和棉籽中添加水平为0.05~0.50 mg/kg时,其平均回收率分别为76.9%~91.1%和76.4%~93.7%,相对标准偏差(RSD)为7.2%~8.2%和6.2%~9.8%;在土壤中添加水平为0.02~0.5 mg/kg时,平均回收率为83.8%~94.6%,RSD为5.3%~8.0%。在山东和河南两地按推荐剂量(有效成分30 g/hm2)和1.5倍推荐剂量(有效成分45 g/hm2)施用10%吡蚜酮·高效氯氟氰菊酯悬浮剂后4 d,吡蚜酮在土壤和棉叶中的残留量分别低于0.02和0.05 mg/kg;至收获时,其在土壤和棉籽中的最终残留量低于0.02和0.05 mg/kg。