Insights into biological delignification of rice straw by Trametes hirsuta and Myrothecium roridum and comparison of saccharification yields with dilute acid pretreatment

Rice straw is the most abundant agricultural residue on a global scale and is widely available as feedstock for cellulosic fuel production. However, it is highly recalcitrant to biochemical deconstruction and also generates inhibitors that affect enzymatic saccharification. Rice straw from eastern Arkansas was subjected to dilute acid pretreatment (160 °C, 48 min and 1.0% sulfuric acid) and solid-state fermentation with two lignocellulolytic fungi, Trametes hirsuta and Myrothecium roridum, and their saccharification efficacies were compared. T. hirsuta and M. roridum were tested separately; pretreatment of rice straw with either strain for seven days resulted in 19 and 70% enrichment of its holocellulose content, respectively. However, liquid chromatography analysis of the alkali extracts showed significant differences in cell wall degradation by T. hirsuta and M. roridum. T. hirsuta removed 15% more phenolic compounds and 38% more glucan than M. roridum, while M. roridum removed 77% more xylan than T. hirsuta. Fungal and dilute acid pretreated biomass was then hydrolyzed using Accellerase^® 1500, a saccharification cocktail. Saccharification efficiency of M. roridum was 37% higher than that of dilute acid pretreatment of rice straw, requiring 8% lower enzyme loading and 50% shorter enzymatic hydrolysis duration. Alkali extraction of fungal pretreated biomass also yielded 10–15 g kg⁻¹ of acid precipitable polymeric lignin (APPL), which is a valuable co-product for biorefineries. In comparison to dilute acid pretreatment, fungal pretreatment could be a cost-effective alternative for the degradation of recalcitrant biomass, such as rice straw.     

Capture of gypsy moth,Lymantria dispar (L.), andLymantria mathura (L.) males in traps baited with disparlure enantiomers and olefin precursor in the People's Republic of China

Pheromone traps baited with (+)-disparlure,cis-7,8-epoxy-2methyocta-decane, captured males ofLymantria dispar, L. monacha, andL. mathura in northeastern People's Republic of China.L. dispar responded to the addition of olefin to (+)-disparlure-baited traps in a negative doseresponse manner. Observations on site and seasonal capture ofL. dispar andL. mathura are discussed.Lepidoptera: Lymantriidae.     

响应面法优化甘油歧化产1,3-丙二醇菌培养基的研究

以甘油为原料,在单因素试验的基础上,利用响应面法研究了(NH4)2HPO4、K2HPO4/KH2PO4、pH值对1,3-丙二醇产量的影响,得到二次多项式回归模型.结果表明:回归模型能很好地反映各因素水平与响应值之间的关系,同时得出这3因素的最佳用量为(NH4)2HPO42.76 g/L、K2HPO4/KH2PO4(质量比1∶1)3.98 g/L、pH值7.58,此时1,3-丙二醇理论产量为28.702 g/L,实际产量为27.597 g/L,比优化前提高了19.02%.     

星点设计-效应面法优化马尾松花粉总黄酮提取工艺

采用超声辅助提取法从马尾松花粉中提取总黄酮,通过单因素实验考察乙醇体积分数、提取时间、料液比以及提取次数等4个因素对马尾松花粉总黄酮得率的影响,并采用星点设计-效应面法优化总黄酮提取工艺。结果表明:马尾松花粉总黄酮的最佳提取工艺条件为乙醇体积分数62.5%,提取时间28.8 min,料液比1∶24,提取次数3次。在此优化条件下,马尾松花粉总黄酮的实际得率为1.37%,与理论值（1.32%）较为接近,表明采用星点设计-效应面法优化马尾松花粉总黄酮提取工艺的方法可行。      

针对建筑群监控的无线传感器网络设计

现代建筑群结构复杂、楼层多,对其实现集中监控的无线传感器网络的网络容量需求大,且在多障碍物的复杂环境下保障无线通信链路具有一定难度。通过分析对比现有主要无线通信技术的特点,设计了一种融合Zigbee技术与433 MHz射频通讯技术的无线传感器网络模型,其中Zigbee网络的实现采用TI公司的Z-STACK协议栈和CC2530 Zigbee模块,433 MHz射频通讯模块选用RFM69H。试验结果表明,该传感器网络能实现半径约600 m的区域内建筑群覆盖,丢包率低于5%,能保障较好的网络服务质量(Qos),整个网络通信在ISM频段,成本低,具有一定应用前景。     

林窗面积对连香树幼苗生长及生物量分配的影响

【目的】为有效保护连香树资源、人工促进连香树群落天然更新和种群形成,探索林窗面积变化对幼苗生长及生物量分配的规律。【方法】以连香树幼苗为材料,通过设置2种林窗面积和林下环境,研究林窗面积对连香树幼苗生长及生物量分配的影响。【结果】不同处理连香树幼苗地径和高呈现极显著差异。小林窗下连香树幼苗高生长和地径生长最大,分别是大林窗和林下处理的108.15%、284.86%和109.13%、197.12%。连香树幼苗在不同处理下叶片形态性状、总生物量以及各营养器官生物量均达到显著水平(P<0.05),其总生物量大小依次为小林窗>大林窗>林下,小林窗单株总生物量分别比大林窗和林下增加134.14%和860.35%。【结论】连香树在幼苗期适宜在光照强度相对较弱的环境下生长,小林窗环境下连香树幼苗生长迅速,生物量分配均衡,苗木竞争力强,有利于幼苗天然更新。     

Characteristic emission of negatively charged particles during tensile deformation of oxide-covered aluminum alloys

Electrons, positive and negative ions as well as photons are known to be emitted from oxide- covered pure polycrystalline Al, Ni, and Ti during tensile deformation. It has been shown that the propagation of cracks in the oxide is uniquely associated with this so-called tribo-stimulated exoemission phenomenon. In this paper we report recent results of tribo-stimulated emission of negatively charged particles from bare and Al-clad aluminum alloys. The investigated samples were anodically oxidized under various conditions such as to produce oxide layers of different thickness as well as chemical and mechanical properties. Of particular interest in this connection are certain porous oxides which facilitate adhesive bonding. The characteristic exoemission curve (emission rate versus strain of the Al substrate) is obtained by measuring the number of emitted negative particles as a function of strain ϵ during tensile deformation of the sample with a constant strain rate dϵ/dt. The features of the curves obtained from different oxides are compared. Initial evidence is presented indicating that the exoemission curve is unique for a given oxide- metal alloy system and has potential as a monitor of certain characteristics of the oxide layer.     

On the stability of conventional and nano-structured carbon-based catalysts in the oxidative dehydrogenation of ethylbenzene under industrially relevant conditions

Relevant carbon-based materials, home-made carbon–silica hybrids, commercial activated carbon, and nanostructured multi-walled carbon nanotubes (MWCNT) were tested in the oxidative dehydrogenation of ethylbenzene (EB). Special attention was given to the reaction conditions, using a relatively concentrated EB feed (10 vol.% EB), and limited excess of O₂ (O₂:EB = 0.6) in order to work at full oxygen conversion and consequently avoid O₂ in the downstream processing and recycle streams. The temperature was varied between 425 and 475 °C, that is about 150–200 °C lower than that of the commercial steam dehydrogenation process. The stability was evaluated from runs of 60 h time on stream. Under the applied reactions conditions, all the carbon-based materials are apparently stable in the first 15 h time on stream. The effect of the gasification/burning was significantly visible only after this period where most of them fully decomposes. The carbon of the hybrids decomposes completely rendering the silica matrix and the activated carbon bed is fully consumed. Nano structured MWCNT is the most stable; the structure resists the demanding reaction conditions showing an EB conversion of ∼30% (but deactivating) with a steady selectivity of ∼80%. The catalyst stability under the ODH reaction conditions is predicted from the combustion apparent activation energies.