豆胶的热反应特性及胶合特性分析

大豆蛋白胶因其可再生、可降解和环保性而受到广泛关注。豆胶的热反应特性和胶合特性研究结果显示:以20℃/min速率升温时,豆胶胶液在157℃时完全固化,在173℃开始降解;胶合板的胶合强度与涂胶量呈线性正相关。按热压温度160℃、热压时间80s/mm、压力1.6MPa、双面涂胶量450g/m2的工艺制备豆胶胶合板,其湿态胶合强度为0.78 MPa,满足GB/T 9846.3-2004《胶合板第3部分:普通胶合板通用技术条件》中Ⅱ类胶合板的要求。     

松香在木材防腐中的应用

从松香降低木材吸湿性、对水基木材防腐剂的固着以及抑木腐菌松香衍生物的制备3个方面讲述了松香在木材防腐中的应用现状.较高浓度的松香乳液处理对提高木材的耐腐性能有一定帮助,较低浓度的松香乳液处理就表现出对易流失的铜盐类防腐剂较好的固定作用.以松香为原料合成的松香胺类、季铵盐等衍生物能够赋予木材较好的耐腐性能,咪唑啉等其它活...     

Drying and rewetting of forest floors: dynamics of soluble phosphorus,microbial biomass-phosphorus,and the composition of microbial communities

Drying and rewetting (D/W) of soils often leads to a pulse of total dissolved phosphorus (TDP) by lysis of sensitive microorganisms. The relevance of D/W on the P cycle in ecosystems depends on the duration of the TDP release. In forest soils, the forest floor represents a hotspot of microbial activity and is often prone to D/W. Here, we investigated the dynamics of TDP, the microbial P pool (Pmic), and the composition of microbial communities after D/W. Samples were taken from Oi and Oe layers of a European beech and a Norway spruce site and desiccated up to ??100 MPa (pF 6) at 20 °C, while controls were kept moist. TDP and Pmic were measured 0, 1, 3, 7, and 14 days after rewetting and the composition of microbial communities was analyzed by automated ribosomal intergenic spacer analysis after 14 days. After D/W, the largest TDP net release (D/W-control) was from Oe layers with 40–50 mg P kg^?1 and inorganic P as the dominant fraction. The TDP concentrations decreased strongly in Oi layers within 1 (beech) to 4 (spruce) days, while remaining stable in Oe layers. The TDP dynamics were linked to the decrease and recovery of Pmic after D/W. Pmic dynamics differed between layers and stand types, suggesting the influence of microbial communities with different D/W sensitivities. The composition of microbial communities varied strongly among sites and layers, while D/W only affected the composition of bacterial and fungal communities in the spruce Oe layer. D/W of forest floors increases the plant available P and affects the P cycle in forest ecosystems.     

A closer look into shrimp yields and mangrove coverage ratio in integrated mangrove-shrimp farming systems in Ca Mau,Vietnam

Shrimp aquaculture is the biggest source of export income in Vietnam. However, the development of the shrimp poses a serious threat to coastal mangroves by converting coastal mangroves into shrimp farms. Much effort has been made to replant mangroves and reduce the impacts of shrimp farming on the environment, and maintaining mangrove coverage at 30–50% of total farm area has provided the highest benefits in the integrated mangrove shrimp model. In this study, we re-examine the benefits of forest cover on the survival and yield of tiger shrimp (Penaeus monodon) in the integrated mangrove shrimp farming systems in Ca Mau province, Vietnam. The study found positive linear correlations of log transformed survival and yield of tiger shrimp with forest cover of the forms: Ln (survival)?=????1.39?+?0.038?×?forest coverage (r²?=?0.22; p value?=?0.0007); Ln (yield)?=?3.55?+?0.026?×?forest coverage (r²?=?0.16; p value?=?0.004). The households with high forest cover (i.e.,?>?45%) also had 1.07?±?0.29 and 1.39?±?0.36 (CI 95%, p value?=?0.000) kg ha^?1 higher yield per night harvest than those with medium and low forest cover, respectively. As a result, households with high forest cover have higher benefits than those with lower forest cover. Our findings together with previous published studies lead to the recommendation that farmers maintain mangroves in farming systems for better economic and environmental benefits.