A Bayesian strategy for combining predictions from empirical and process-based models

We present a strategy for using an empirical forest growth model to reduce uncertainty in predictions made with a physiological process-based forest ecosystem model. The uncertainty reduction is carried out via Bayesian melding, in which information from prior knowledge and a deterministic computer model is conditioned on a likelihood function. We used predictions from an empirical forest growth model G-HAT in place of field observations of aboveground net primary productivity (ANPP) in a deciduous temperate forest ecosystem. Using Bayesian melding, priors for the inputs of the process-based forest ecosystem PnET-II were propagated through the model, and likelihoods for the PnET-II output ANPP were calculated using the G-HAT predictions. Posterior distributions for ANPP and many PnET-II inputs obtained using the G-HAT predictions largely matched posteriors obtained using field data. Since empirical growth models are often more readily available than extensive field data sets, the method represents a potential gain in efficiency for reducing the uncertainty of process-based model predictions when reliable empirical models are available but high-quality data are not.     

哌嗪氨基二硫代甲酸型螯合树脂的合成及其吸附性能

用哌嗪和二硫化碳反应合成氨基二硫代甲酸中间体，再与二卤代烃反应得到1，4-双(二硫代酯基)哌嗪聚合物，考察了中间体和螯合树脂对Ag^ ，Cu^2 ，Zn^2 ，Ni^2 ，CO^2 ，Pb^2 ，Pd^2 ，Cr^3 的静态吸附性能，结果表明，两者均可以吸附金属离子，缩聚后的螯合树脂具有更强的吸附能力。     

A straightforward synthesis in aqueous medium of enantiomerically enriched S(-)2,2′-dihydroxy-1,1′-binaphthyl

Chiral, atropisomeric 2,2'-dihydroxy-1,1'-binaphthyl has been extensively used to direct asymmetric processes. Its key role in asymmetric catalysis has spurred efforts to synthesize it in the optically pure form, but the reported synthetic routes have a significant environmental impact. In an aqueous peroxydase-cyclodextrin system the oxidative coupling of 2-naphthol took place very rapidly in almost quantitative yield and resulted in an enantiomeric excess. This one-pot synthesis do not require any organic solvents and oxidising metal cations.     

Increasing the microbial activity in activated sludge by the phenomenon of 'biological resonance

Mechanical oscillations as well as electrical oscillations (e.g. in an electrical oscillatory circuit) can lead to resonance conditions by external agitation with the natural frequency of the system. During the microbial protein synthesis, the induction and repression mechanisms also cause oscillations in the form of varying protein concentrations. The aim of this work concentrates on an induced resonance case of the biological system, comparable with physical resonance phenomena, by external periodic stimulations. For this, system theoretical computer simulations with a structured genetic model were carried out, which built the theoretical fundament for describing the effect of 'Biological Resonance'. Based on that, lab-scale experiments using a mixed microbial culture (activated sludge) and skimmed milk as an inducing substrate revealed an enhanced microbial productivity of around 60%-75% compared to values of the productivity under steady-state conditions in a narrow range of process parameters. The optimum (resonance case) was confirmed by a repetition of the variation experiments and is characterised by a substrate supply period of approx. 18 min and a following starvation period of about 9 min. Long-term investigations under optimised process conditions indicate adaptation mechanisms of the microorganisms to evade the imposed stress conditions. The productivity will not remain constant without additional stimulation and declines to its original level. However, temporal modulation of the starvation period permanently increases the productivity (elevated catabolism) to about 60%, which was observed over a period of several weeks.     

可生物降解材料聚羟基脂肪酸酯（PHA）的合成与应用概述

聚羟基脂肪酸酯（polyhydroxyalkanoates,PHA）是很多微生物合成的一种细胞内聚酯,是一种天然的高分子生物材料。PHA具有良好的生物相容性能、生物可降解性和塑料的热加工等性能。文章主要综述了PHA的合成途径与有关应用方面的研究。     

铜藻基载铁活性炭的制备及其对亚甲基蓝的吸附特性研究

以一种大型海藻——铜藻为原料,Fe Cl3·6H2O为活化剂,采用超声浸渍-原位合成法制备了铜藻基载铁活性炭(Fe/SAC),并以活性炭得率和亚甲基蓝吸附值为指标,通过正交法考察了活化温度、活化时间和浸渍比的影响.同时,采用X射线衍射、扫描电镜和比表面积分析仪对最优结果进行表征,并考察了Fe/SAC吸附亚甲基蓝的热力学与动力学特性.结果表明,Fe/SAC的最优制备工艺条件为活化温度600℃、活化时间1 h、浸渍比1∶1,此时的活性炭得率为39.5%,亚甲基蓝吸附值为255.67 mg·g~(-1);最优工艺条件下制得的Fe/SAC比表面积为558.31 m2·g~(-1),其负载的铁组分主要为Fe3O4和Fe O;亚甲基蓝在Fe/SAC上的吸附过程符合准二级动力学模型,Langmuir等温吸附模型能够很好地描述吸附平衡过程,该吸附是熵增加的自发吸热(ΔS0、ΔG0、ΔH0)过程,升温有利于吸附.     

内蒙镶黄旗人群胃癌环境病因的研究──关于人体内合成亚硝胺的评估

测定了内蒙古自治区锡盟镶黄旗１５个不同地点水样中的ＮＯ＾－２含量。实验结果显示,１５个地点水样中ＮＯ＾－２的含量相差很大,大致分为Ａ、Ｂ、Ｃ３组,其平均值分别为０．１８６、０．６４０、３．８５０μｇ／ｍｌ。     

二甲基二烯丙基氯化铵的合成

为制备聚二甲基二烯丙基氯化铵絮凝剂,采用二步法制备了二甲基二烯丙基氯化铵单体,即在强碱性条件下由烯丙基氯和二甲胺反应先生成二收藏 －烯丙基叔胺,将该叔胺分离出来并再次加入烯丙基氯同会２丙介质中结晶析出委胺晶体。     

基于能量合成法的塔式结构刚度识别研究

在Rayleigh能量法和Southwell's频率合成法的基础上,将结构的振动基频表示为由各变形元和惯性元组成的子系统频率的合成,其中变形元为结构的弯曲变形和剪切变形,惯性元为结构的分布质量和塔顶附加质量。通过选取满足边界条件的挠度函数,建立了底部固定、顶端带有附加质量的塔式结构基频与刚度的关系,因此可通过测量结构的振动基频识别出塔式结构的抗弯刚度和抗剪刚度。以某钢塔为计算实例,采用该算法推导出了结构振动基频与弹性模量的关系,只要知道截面的几何尺寸和材料性质,便可快速识别出各截面的刚度。有限元空间建模计算结果证明了本文提出的算法具有较高精度。该方法适合底部固定的塔式结构,可为复杂空间塔式结构使用状态的监测与评估提供参考。     

Optimizing synthesis conditions of nanoscale zero-valent iron (nZVI) through aqueous reactivity assessment

Nanoscale iron particles (nZVI) is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a facile method to screen the reactivity of candidate nZVI materials produced using different methods or under varying synthesis conditions has yet been established. In this study, four reaction parameters were adjusted in the preparation of borohydride-reduced nZVI. The reductive properties of the resultant nanoparticles were assayed independently using two model aqueous contaminants, Cu(II) and nitrate. The results confirm that the reductive reactivity of nZVI is most sensitive to the initial concentration of iron precursor, borohydride feed rate, and the loading ratio of borohydride to ferric ion during particle synthesis. Solution mixing speed, in contrast, carries a relative small weight on the reactivity of nZVI. The two probing reactions (i.e., Cu(II) and nitrate reduction) are able to generate consistent and quantitative inference about the mass-normalized surface activity of nZVI. However, the nitrate assay is valid in dilute aqueous solutions only (50 mg·L⁻¹ or lower) due to accelerated deactivation of iron surface at elevated nitrate concentrations. Additional insights including the structural and chemical makeup of nZVI can be garnered from Cu(II) reduction assessments. The reactivity assays investigated in this study can facilitate screening of candidate materials or optimization of nZVI production parameters, which complement some of the more sophisticated but less chemically specific material characterization methods used in the nZVI research.