水性异氰酸酯木材胶黏剂耐久性研究

通过红外、热重和压剪强度分析,对水性异氰酸酯(API)木材胶黏剂在加速老化处理1~7个周期(A1~A7)和湿热老化处理1~7个周期(H1~H7)的耐久性进行了研究。红外分析表明:未处理的API胶膜(S)含有大量的异氰酸酯基团,A1~A7的API胶膜中异氰酸酯基团全部消失,H1~H3的API胶膜中仍有异氰酸酯吸收峰存在,但强度减弱,H4~H7的异氰酸酯基团消失。热重分析结果表明:A1~A4胶膜的初期热稳定性优于H1~H4,5~7个周期热稳定性几乎相同。在相同质量损失下,加速老化处理API胶膜更稳定,A1~A7降解活化能不完全相同,即降解速度不同;而H1~H7胶膜的活化能几乎相同。2种处理方法胶合制品的压剪强度随时间延长逐渐降低,加速老化处理到第3个周期压剪强度仅为5.32MPa,湿热老化处理到第5个周期压剪强度降为6.92 MPa,均达不到国家标准。     

不同条件水热处理对思茅松漂白工艺的影响

实木经水热处理后,木材颜色有所变。为此,对不同水热处理后的思茅松实木进行了漂白工艺试验,并根据试验结果选出了与水热处理条件相对应的最佳漂白工艺及影响漂白效果的主要因素。结果表明,同一树种不同水热处理条件下试件的白度不同,与之对应的较佳的漂白工艺亦不同。     

Germination Syndromes and Their Relevance to Rangeland Seeding Strategies in the Intermountain Western United States

Rangelands in the western United States exhibit extremely high temporal variability in seedbed microclimate, and this variability contributes to poor establishment of revegetation species that are typically planted in the fall. We conducted long-term simulations of cumulative germination as a function of planting date and identified alternative germination syndromes based on population-level responses to environmental variability. These germination syndromes reveal ecologically significant differences but also noteworthy similarities in species and seed lot response that can inform rangeland restoration planning and management. Seed germination may occur much sooner than assumed under the traditional paradigm of fall-planting/spring-emergence in the intermountain western United States, and seed germination per se does not appear to be a bottleneck for successful establishment in most years. Instead, simulations of germination response support recent hypotheses that postgermination/preemergent mortality may be the larger contributor to poor seedling establishment. Our data support two general strategies to improve the likelihood of seedling survival into the spring: seeding as late as possible in the fall and active diversification of germination syndromes within a given seed mix. Consistent application of these strategies could increase the probability that some seeds are always available to take advantage of any pulse of seedbed favorability in the late fall, winter, or early spring.     

戊内酯/水体系中磷钨酸铝催化葡萄糖转化制备5-HMF

利用离子交换技术制备了催化剂磷钨酸铝(AlPW12O40),采用FT-IR、XRD、电位滴定和ICP技术对催化剂AlPW12O40进行了系统表征.在水热条件下,对AlPW12O40催化葡萄糖转化制备5-羟甲基糠醛(5-HMF)进行了研究,考察了反应温度、时间、催化剂用量和溶剂配比对5-HMF得率的影响.研究结果表明:在...     

Cooling Capability of Duct-ventilated Highway Embankment Enhanced by Self-windward Vent

For the duct-ventilated highway embankments in permafrost regions of the Qinghai-Tibet Plateau, the cooling capability of duct-ventilated embankment enhanced by a self-windward vent is focused. Based on the intake-air volume in the ventilation pipe, the factors influencing the cooling capability in duct-ventilated embankment enhanced by a self-windward vent are analyzed. The analysis results indicate that the enhancement of the cooling capability in the duct-ventilated embankment with a self-windward vent is significant during winter months. For the self-windward vent equipped on the top of the vertical pipe, the cooling capability during winter months in the embankment increases with the increase of vertical pipe height. Convective heat transfer is a dominant mode of heat exchange between the ventilation pipe wall and the ambient air in the duct-ventilated embankment. From a convective heat transfer point of view, the height of self-windward vent installed ought to be as high as possible. However, due to disturbance of the wind field near both sides of the duct-ventilated highway embankment caused by the running vehicles, the height of self-windward vent shouldn’t exceed the embankment height.     

低温热水地板辐射采暖系统与节能技术

本文吸收引进国外成熟的先进经验,提出一种适合我国国情的低温热水地板辐射采暖技术。它与对流采暖方式相比,具有节能、节材、节约占地空间等特点。通过实践与测试的结果表明,这种低温热水地板辐射采暖技术在满足人们舒适的基础上做到降低能耗,具有推广价值。     

水热及水热氧化预处理对木屑成型颗粒理化性质的影响

生物质成型处理可以提高生物质的能量密度而降低其运输与储存成本,有利于生物质资源的综合利用。该研究以杉木屑为研究对象,经170～260 ℃水热及水热氧化预处理后制备成型颗粒,并使用范式法、X射线衍射仪和热重分析仪等测试手段分析了水热及水热氧化预处理过程对木屑及其成型颗粒理化性能的影响。结果表明：与原料相比,水热及水热氧化预处理后木屑成型颗粒的机械性能从原料的16.2 MPa分别增至38.9 和41.1 MPa,水热氧化预处理对木屑的机械性能提升更有效。在水热及水热氧化预处理过程中,随着预处理温度上升,木屑样品的结晶度均呈现先升高后降低的趋势,分别在230和200 ℃时达到最高值,且成型颗粒的机械性能与木屑中纤维素含量及其结晶度呈正相关趋势,结晶纤维素是影响其成型过程的关键组分。与原料相比,水热及水热氧化预处理明显改善了木屑成型颗粒的燃料品质及其燃烧性能,成型燃料的热值、综合燃烧指数和稳燃指标均得到明显提升,其中水热氧化处理更有利于木屑炭化程度的提升。     

Hydrochar amendment promotes microbial immobilization of mineral nitrogen

Hydrochars and biochars are products of the carbonization of biomass in different conversion processes. Both are considered suitable soil amendments, though they differ greatly in chemical and physical composition (e.g., aromaticity, inner surface area) due to the different production processes (pyrolysis, hydrothermal carbonization), thus affecting their degradability in soil. Depending on the type, char application may provide soil microorganisms with more (hydrochars) or less (biochars) accessible C sources, thus resulting in the incorporation of nitrogen (N) into microbial biomass. A soil‐incubation experiment was conducted for 8 weeks to determine the relationship between mineral‐N concentration in the soil solution and microbial‐biomass development as well as soil respiration. An arable topsoil was amended with two hydrochars from feedstocks with different total N contents. Biochars from the same feedstocks were used for comparison. Both char amendments significantly decreased mineral‐N concentration and promoted microbial biomass compared to the nonamended control, but the effects were much stronger for hydrochar. Hydrochar application increased soil respiration significantly during the first week of incubation, simultaneous with the strongest decrease in mineral‐N concentration in the soil and an increase in microbial biomass. The amount of N detected in the microbial biomass in the hydrochar treatments accounted for the mineral N “lost” from the soil during incubation. This shows that microbial immobilization is the main sink for decreasing mineral‐N concentrations after hydrochar application. However, this does not apply to biochar, since the amount of N recovered in microorganisms was much lower than the decrease in soil mineral‐N concentration. Our results demonstrate that while both chars are suitable soil amendments, their properties need to be considered to match the application purpose (C sequestration, organic fertilizer).     

生长基质性状对肋脉羊肚菌矿质元素含量的影响

[目的]为羊肚菌的进一步研究和开发利用可提供依据。[方法]研究生长基质的理化性质和矿质元素的含量对羊肚菌矿质元素的吸收及其生物学特性与药理活性的影响。[结果]结果表明:肋脉羊肚菌原产地土壤pH值范围为8.52~8.55;土壤中重金属含量达到国家一级土壤环境标准;肋脉羊肚菌中含有丰富的微量元素,以K、Ca、Mg为主,其次为Fe、Sr、Zn、Cu,重金属As、Cd、Pb、Hg等未检出,肋脉羊肚菌的锌铜比值为4.77。[结论]肋脉羊肚菌具有较高的药用研究和开发价值。