基于ART-2人工神经网络的煤矿安全风险评价

旨在为煤矿安全风险预控管理提供一种适用的风险评价模型或方法。研究过程中,介绍了人工神经网络自适应共振理论的ART-2算法;在安全系统工程理论及相关研究基础上,结合调研分析建立了风险评价指标体系;选取山西9家煤矿作为研究样本进行实证研究。该算法仿真识别结果与煤矿实际安全风险情况一致性程度达到77.78%,表明针对煤矿安全风险预控管理过程中的安全风险评价,ART-2神经网络具有较好的适用性。     

Changes in methylmercury accumulation in the brain of rat offspring throughout gestation and during suckling

Higher methylmercury (MeHg) accumulation and susceptibility to toxicity in the fetus than in the mother at parturition is well known. However, the degree of MeHg accumulation in the brain during the late pregnancy period when the human brain is most vulnerable is not clear. In addition, changes in MeHg accumulation in the developing rat tissues with consecutive exposure throughout gestation and lactation periods have not been well studied. The purposes of this study were to evaluate the changes in MeHg accumulation in the brain and other tissues of the offspring, based on constant and consecutive doses of MeHg to mothers throughout gestation and lactation. Adult female rats were given a diet containing 5?ppm?Hg (as MeHg) for 8 weeks. Then they were mated and subsequently given the same diet throughout gestation and lactation. On embryonic days 18, 20, 22 and at parturition, the concentrations of Hg in the brains of the offspring were approximately 1.5–2.0 times higher than those in the mothers. On the other hand, during the suckling period Hg concentrations in the brain rapidly declined to about 1/10 of that during late pregnancy. Changes in MeHg accumulation in the blood and liver after parturition were similar to those in the brain. Thus, although mothers are subjected to constant and prolonged MeHg exposure throughout both the gestation and lactating periods, the risk to the offspring may be especially high throughout the late gestation period but rapidly decreases during the suckling period     

顶棚装修材料对地下商业街火灾影响的数值模拟研究

地下商业街处于相对封闭的环境,在强制通风不利的情况下,内装修材料可燃性对火灾影响显得特别重要。应用FDS火灾模拟软件的大涡模拟(LES)模型,对分别采用木质、石膏板、PVC材质顶棚的地下商业街进行火灾模拟,重点讨论了不同顶棚材料对烟气温度、体积分数的影响。模拟结果表明,木质顶棚装修材料明显增加烟气体积分数、加速火灾轰然的形成。烟气蔓延速度快,烟气中CO最高浓度是其他两种材料的40倍,因此应限制地下商业街商户装修中使用木质顶棚材料。     

苍山5.2级地震前后井水位固体潮加卸载响应比的短临异常变化

将尹祥础固体潮加卸载响应比的理论和方法引入到地下水位潮汐资料计算中,从岩石的应变与应力的非线性响应分析了井水位固体潮加卸载响应比的物理机理,从理论上论证可以应用地下水位观测资料来计算加卸载响应比,并研究出利用地下水位对固体潮响应来计算加卸载响应比的方法。以此方法计算了山东省莒南井（Ｌｕ １４井）水位的固体潮加卸载响应比,分析了１９９５年苍山５２级地震前后井水位固体潮加卸载响应比的短临异常变化。     

小麦秸秆生物炭对水中对羟基苯甲酸乙酯的吸附特性

对羟基苯甲酸乙酯属于尼泊金酯类物质,是一种典型的新兴环境污染物.本研究通过制得不同热解温度(300、500和700℃)下的小麦秸秆生物炭(分别表示为BC300、BC500、BC700),对水中对羟基苯甲酸乙酯进行间歇吸附.结果表明,热解温度升高会导致生物炭表面疏水性增强,且引起零电荷点从8.37升至9.42.溶液初始p H值由8升至12时,对羟基苯甲酸乙酯去除率显著递减;此外,溶液离子强度的增强会导致对羟基苯甲酸乙酯去除率的下降.生物炭吸附水中对羟基苯甲酸乙酯的等温吸附过程符合Langmuir方程,其中,最大吸附容量排序为:BC700BC500BC300.同时,吸附过程符合准二级动力学方程,且为吸热自发过程.此外,经过4轮再生吸附,生物炭吸附容量仍可达到最初的90%,其中,BC700展示出最高的吸附效率(92.76%).     

Optimal subsidies for distributed photovoltaic generation: Maximizing net policy benefits

Distributed photovoltaic (PV) generation is a promising pathway for reducing carbon emission and meeting energy demands in electricity sector. Subsidies are essential to accelerate its deployment. This paper aims to study the optimal subsidy levels for distributed PV generation from the perspective of maximizing the net policy benefits (environmental and economic) by applying the principal–agent theory, which is a commonly used method of analyzing government incentive issues. Based on a detailed analysis of asymmetric information and of benefit conflicts between the government (the principal) and the investor (the agent), the optimal subsidy principal–agent model is established, in which the investor’s preference toward distributed PV generation is asymmetric and is described by a random variable. The equivalent model is then presented to obtain the optimal solutions, and a numerical example is provided to test the effectiveness of the model and to illustrate the implications of the solutions. The results show that high net policy benefits are directly influenced by a high investor preference. This emphasizes the importance for the government of improving the investor’s preference level and of eliminating asymmetric information to develop distributed PV generation and reduce subsidy costs. Additionally, lowering the market risk and enlarging the overflow value of distributed PV generation both contribute to subsidy cost savings. This paper offers policy makers an effective subsidy scheme to accelerate distributed PV generation development and will also be a useful reference for government to subsidize other renewable power systems to mitigate global climate and energy changes.     

硫代硫酸钠对排硫硫杆菌固碳能力的影响及其作用机制

通过测定不同浓度Na_2S_2O_3·5H_2O培养时排硫硫杆菌(DSM 505)菌液的总有机碳浓度(TOC),分析Na_2S_2O_3·5H_2O对排硫硫杆菌固碳能力的影响,并结合各浓度Na_2S_2O_3·5H_2O条件下固碳关键酶Rubis CO编码基因cbb的转录特性和胞外游离有机碳浓度(EFOC),阐明Na_2S_2O_3·5H_2O影响排硫硫杆菌固碳能力的作用机制.结果表明,适当范围内增加Na_2S_2O_3·5H_2O的浓度能显著提高排硫硫杆菌的固碳能力,降低胞外游离有机碳在总有机碳中所占的比例.cbb基因转录特性分析结果表明,Na_2S_2O_3·5H_2O浓度对cbb基因的转录效率和表达模式均无显著影响.因此推测Na_2S_2O_3·5H_2O影响排硫硫杆菌固碳能力的作用机制可能是作为电子供体提供能量,促进细胞骨架合成,从而削弱胞外游离有机碳对排硫硫杆菌自养过程的抑制作用,进而增强固碳能力.     

Model microgravity enhances endothelium differentiation of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are capable of differentiation into multilineage cell types under certain induction conditions. Previous studies have demonstrated that physical environments and mechanical force can influence MSC fate, indicating that these factors may be favorable inducers for clinical treatment. Our previous study found that MSCs are spread with a spindle shape when cultured in normal gravity (NG), and under modeled microgravity (MMG) for 72 h, they become unspread and round and their cytoskeleton fibers are reorganized. These morphological changes affected the function of MSCs through the activity of RhoA. We examined the responses of MSCs under MMG stimulation, followed with VEGF differentiation. We found that MSCs under MMG for 72 h were differentiated into endothelial-like cells by detecting the expression of endothelial-specific molecules (Flk-1 and vWF), which were also able to form a capillary network. Their endothelial differentiation potential was improved under MMG compared with that under NG. We believe that this method is a novel choice of MMG stimulation for neovascularization. This phenomenon may increase the potential of MSC differentiation, which might be a new strategy for the treatment of various vascular diseases and improve vascularization in tissue engineering.     

阿魏酸和香豆素对铜绿微囊藻的化感作用

通过对铜绿微囊藻(Microcystis aeruginosa)的藻液D680、叶绿素a、电导率(EC)值以及超氧阴离子自由基O.2-含量的测定,研究了不同浓度的阿魏酸和香豆素对铜绿微囊藻的生长抑制作用及其机制.结果表明,阿魏酸和香豆素对铜绿微囊藻的生长均产生"低促高抑"作用,浓度高于100 mg.L-1的阿魏酸和香豆素对铜绿微囊藻表现出明显的抑制作用,200 mg.L-1的阿魏酸和香豆素第6 d的平均抑藻率分别为80.3%和58.0%.在高浓度阿魏酸和香豆素抑制作用下,铜绿微囊藻的叶绿素a含量迅速降低、EC值和O.2-含量明显增大,说明化感物质可能通过破坏细胞膜、增加O.2-含量、降低叶绿素a含量等作用抑制藻细胞的生长.此外,种子发芽实验结果表明,阿魏酸较香豆素毒性小.     

邻苯二甲酸二甲酯的紫外光-H2O2降解机制研究

为研究邻苯二甲酸二甲酯(DMP)在紫外光(UV)-H2O2体系下的光降解机制,利用质谱仪鉴定了目标化合物的降解产物,并借此推测其可能的降解途径.结果表明,在UV-H2O2的体系中,10 mg.L-1的DMP在90 min内的降解率达到92.3%,溶液pH值由初始的6.50降至4.98.通过GC/MS、LC/MS分析,DMP在UV-H2O2降解过程中的产物有六类,并且推断出DMP的两条侧链同时发生水解作用,生成的邻苯二甲酸可以异构为更加稳定的对苯二甲酸.此外,DMP还可以发生苯环取代、侧链缩合成环等反应,最后,在.OH的作用下,DMP及其芳香族中间产物发生开环反应,苯环被破坏,生成多种小分子有机酸,并进一步矿化为CO2和水.