聚丙烯—一种潜在的管道覆盖层新型材料

包覆聚乙烯是当前钢质管道所用的主要防腐层之一，但是，它存在着易发生环境应力开裂，使用温度较低的缺点，聚丙烯作为管道包覆材料，与聚乙烯相比有其相同之处，两者的流劝指数相差不大，力学性质相当，只是聚丙烯的硬度和刚度大一些，不同之处；聚丙烯的耐环境环境温度高于聚乙烯，聚丙烯在－２０℃条件下都具有良好的冲击强度，这对于要求施工环境温度低，生产使用温度高，并有表面活性介质的环境中的长输原油管道来说，聚丙烯将     

Mass loss and nutrient release during litter decay in peatland: The role of microbial adaptability to litter chemistry

In peatlands the reduced decomposition rate of plant litter is the fundamental mechanism making these peat-accumulating ecosystems effective carbon sinks. A better knowledge of litter decomposition and nutrient cycling is thus crucial to improve our predictions of the effects of anthropogenic perturbation on the capacity of peatlands to continue to behave as carbon sinks. We investigated patterns of plant litter decomposition and nutrient release along a minerotrophic-ombrotrophic gradient in a bog on the south-eastern Alps of Italy. We determined mass loss as well as P, N, K, and C release of seven vascular plant species and four moss species after 1 year in both native and transplanted habitats. Hence, differences in litter decay were supposed to reflect the degree of adaptability of microbial communities to litter quality. Polyphenols/nutrient and C/nutrient quotients appeared as the main parameters accounting for decomposition rates of Sphagnum litter. In particular, litter of minerotrophic Sphagnum species decomposed always faster than litter of ombrotrophic Sphagnum species, both in native and transplanted habitats. Decomposition rates of vascular plant litter in native habitats were always higher than the corresponding mass loss rates of Sphagnum litter. Minerotrophic forbs showed the fastest decomposition both in native and transplanted habitats in accordance with low C/P and C/N litter quotients. On the other hand, C/P quotient seems to play a primary role also in controlling decomposition of graminoids. Decomposition of deciduous and evergreen shrubs was negatively related to their high lignin content. Nitrogen release from Sphagnum litter was primarily controlled by C/N quotient, so that minerotrophic Sphagnum litter released more N than ombrotrophic Sphagnum litter. Overall, we observed slower N release from litter of ombrotrophic vascular plant species compared to minerotrophic vascular plant species. No single chemical parameter could predict the variability associated with different functional groups. The release of K was very high compared to all the other nutrients and rather similar between ombrotrophic and minerotrophic litter types. In Sphagnum litter, a higher C/P quotient was associated with a slower P mineralisation, whereas a faster P release from vascular plant litter seems primarily associated with lower C/P and polyphenols/P quotients.     

Decomposition characteristics of cotton stalks from fall to spring as affected by continuous cropping

Knowledge about cotton (Gossypium hirsutum L.) stalk degradation is important for understanding nutrient cycling in soil. The objective of this experiment was to study the effects of continuous cropping on cotton stalk decomposition and nutrient release patterns from fall to spring. Cotton stalks were placed inside nylon mesh bags on 5 October and then buried 15?cm deep in fields that had been continuously cropped to cotton for 1, 10, or 20 yrs. The results showed that the decomposition rates (i.e. mass loss) were significantly greater in the 10- and 20-yr soils than in the 1-yr soil during the first 16 d after burial. The decomposition rates were similar in all three soils between d 16 and 177. However, between d 177 and 193, the decomposition rates were the highest in the 1-yr soil. Overall, stalk mass declined by 35–40% during the 193 d experiment. The largest decreases in stalk mass were in the 1- and 10-yr soils. After 193 d, 95–97% of stalk K had been released compared with 29–34% of stalk P, and 41–48% of stalk N. The duration of continuous cropping had no significant effect on δ¹³C, N, and K release rates. The release rate of stalk P was the greatest in the 20-yr soil followed by the 1-year soil and then the 10-yr soil. In conclusion, the duration of continuous cotton cropping significantly affected the decomposition characteristics of cotton stalks. Additional studies will be done to learn more about how N application and irrigation can be managed in the fall so that (i) undecomposed residue does not interfere with spring sowing and (ii) the nutrients in the stalks are not lost after decomposition.     

Dielectric properties of Simon poplar wood flour/polypropylene composite at oven-dry state

Interfacial compatibility is a crucial factor to the performance of wood-plastic composites （WPCs）. Yet, so far, the coupling mechanisms of WPC have not been completely understood. In order to further clarify the interfacial coupling mechanism, the dielectric constant and dielectric loss factor of Simon poplar wood flour/polypropylene composites without additives at different wood contents were measured at oven-dry state, and parameters and thermodynamic quantities of the relaxation process were also analyzed and calculated. Consequently, an obvious relaxation process based on the reorientation of methanol groups in amorphous region of wood cell wall was observed exactly that its dielectric loss factor peak decreased with the decreasing wood content within the measured range of 50%-100%. With the trend of dielectric relaxation strength, the two changing trends both revealed that the existence of polypropylene could hinder reorientation of methanol groups. Following the decreasing wood contents, the effect of the hindrance on the dielectric properties turned obvious gradually. It elucidated that introduction of polypropylene caused the quantities of hydrogen bonds formed between each methanol group and the groups around it change. The same conclusion could be drawn from the analysis of thermodynamic quantities during the dielectric relaxation progress.     

不同果袋对丰水梨果实品质的影响

[目的]筛选出综合效果好、适合丰水梨的果袋。[方法]以不套袋为对照,研究9种类型果袋套袋对丰水梨果实品质的影响。[结果]套袋处理可明显改善丰水梨的果皮色泽、果点密度和大小,套袋果实直径较对照平均增加2.97 mm,单果重较对照平均增加17.73 g。丰水梨套袋后果实可溶性固形物、可溶性总糖的含量及果肉硬度大多下降,固/酸比值大多提高。套袋处理的果实外观总分较对照提高1.18～2.88分,套袋对丰水梨果实内在品质的总体效果在9种果袋之间差异较大。[结论]套袋效果最佳的果袋是外袋外白内黑、内袋黑色双层纸袋,综合得分、外观总分均第1,内在品质总分第2,然后是内袋黑色、外袋灰色双层纸袋和内袋黑色、外袋灰黑色双层纸袋。     

Improvement in compatibility and mechanical properties of modified wood fiber/polypropylene composites

To improve the interfacial compatibility between wood fibers and polypropylene and the toughness of wood-fiber/polypropylene composites, maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymers (SEBS-g-MAH) were used as modifiers. Mechanical properties of wood-fiber/polypropylene (WF/PP) composites were improved when PP-g-MAH or SEBS-g-MAH was added. When either of these copolymers was added, the composites had better interfacial compatibility than the unmodified composite. This was verified by scanning electron microscope (SEM) observations and dynamic mechanical analysis (DMA). The mechanical properties of the composites were significantly improved because of the good interfacial bonding between wood fibers and polypropylene when PP-g-MAH and SEBS-g-MAH were added. __________ Translated from Journal of Beijing Forestry University, 2007, 29(2): 133–137 [译自: 北京林业大学学报]     

Mesh repair of a large traumatic lateral abdominal wall hernia in an 8‐day‐old foal

An 8‐day‐old French trotter colt was admitted with a traumatic lateral abdominal wall hernia with reducible intestinal content. A 15 cm long full thickness tear was identified in both the internal abdominal oblique and transverse abdominal muscles. This case report describes the surgical repair of the hernia using a polypropylene mesh.     

不同精粗比日粮添加甘露寡糖对绵羊瘤胃纤维降解率的影响

选取6只安装永久瘤胃瘘管羯羊(白萨福克♂×小尾寒羊♀)为瘤胃液供试动物,采用4×6二因子析因试验设计,共设2个因子,分别为不同精粗比日粮(A1(20:80)、A2(30:70)、A3(40:60)、A4(50:50))和不同甘露寡糖添加量(B1 (0)、B2 (0.4%)、B3 (0.8%)、B4 (1.2%)、B5 (1.6%)、B6 (2.0%)),进行尼龙袋半体内试验,旨在研究不同精粗比日粮中添加甘露寡糖对绵羊瘤胃中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)降解率的影响。结果表明,A因子对日粮中不同时间点NDF、ADF瘤胃降解率、降解参数及有效降解率均产生了显著影响(P< 0.05),A1处理组的NDF和ADF各个时间点(除3 h外)的瘤胃降解率均显著高于A3和A4处理组(P< 0.05);B因子对3、6、9、12、48 h的瘤胃ADF降解率均产生了显著影响(P< 0.05),其中B5处理组显著高于B1、B2处理组(P< 0.05);A3处理组的NDF有效降解率显著高于A1、A2处理组(P< 0.05),稍高于A4处理组(P >0.05)。综上所述,在精粗比为40:60时,NDF和ADF的瘤胃有效降解率处于较高水平。     

植生带(袋)的分类及其在边坡治理上的应用

植生带(袋)分为植生带和植生袋等形式,广泛应用于草坪绿化,边坡复绿,尤其是在高等级公路边坡、废弃矿山、河流堤岸等生态环境恢复与重建工程应用日益广泛。现就植生带(袋)的分类及其在边坡复绿上的应用进行了综述。     

黑荆木屑发酵处理后袋栽香菇试验研究

通过对黑荆树木屑进行发酵处理,有效地降解木屑中的单宁含量,从而克服了出菇初期长“蜡烛状畸形菇”的现象,为利用黑荆木屑袋栽香菇获得优质高产提供了切实可行的技术措施