轴向约束钢柱温度应力影响因素研究

建筑结构多为超静定结构.火灾条件下,组成结构的各构件在受到不均匀温度作用时,构件内将会产生温度应力.温度应力增加了构件的作用荷载,并影响受火钢柱的稳定性,是导致约束钢柱屈服破坏的主要原因.根据文献分析,轴向约束钢柱的温度应力影响因素主要有轴向约束刚度、长细比、初应力水平和构件升温.采用试验方法研究各因素对约束钢柱温度应力的影响规律.在温度应力增长阶段,构件所产生的温度应力与构件的温度升高值之间为线性关系,温度越高,温度应力越大.温度应力随轴向约束刚度和长细比的增大而增大;初应力水平越高,温度应力值越小.初应力水平的大小不影响温度应力的增长,但决定构件何时进入塑性状态.     

框架柱抗震抗火设计因素分析

在介绍地震火灾危害基础上,分析了钢筋混凝土框架柱地震与火灾引起的破坏形式,论述了同时考虑抗震与抗火的钢筋混凝土框架柱相悖与相符的设计因素及其依据,给出了相悖设计因素的弥补方法。相关结论对需要同时考虑抗震与抗火的钢筋混凝土框架柱的设计具有一定的指导意义。     

铜锰基整体式催化剂对烧结烟气CO净化特性

基于改性铜锰氧化物作为CO催化活性组分,分别制备了催化剂原粉、以泡沫金属、堇青石为载体的两种整体式催化剂,在实验室配气条件下对比了3种样品的CO催化效率及稳定性,优选了堇青石整体式催化剂,并在某钢厂实际烧结烟气条件下测试了其在不同催化剂负载量、空速、温度下的CO催化效率、稳定性以及衰减后样品催化特性;最后批量制备了2m³优选整体式催化剂并开展了6000m³/h烧结烟气CO净化中试实验.结果表明,烟气高浓水蒸气显著抑制CO催化反应,经240h催化后T₉₀最大提升38℃;催化剂负载量越高,T₉₀越低,催化效率衰减时间越短,稳定后的效率越高,但随着空速增加,该优势减小;1440h(2个月)中试实验中,进气温度185~195℃下,CO催化效率大于85%(平均90%),出口CO浓度低于1000×10^-6,出口平均烟温达220℃,具有节能减排双重效益.     

Erratum

The influence of soil macro-porosity and manure on atrazine (6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine) transport was investigated under laboratory conditions using disturbed and undisturbed soil columns. The macro-porosity in the soil column was obtained with CT scanning technique. Liquid manure was applied at the surface of soil column, 19 cm long and 8 cm in diameter, at a rate of 60 m³/ha. Experimental results revealed that atrazine moves faster through the soils in the presence of manure compared to soil without application of manure. The average time for elusion and the relative peak concentration in the disturbed soil column without manure was 14.5 h and 3.1%, respectively compared to 11.0 h and 6.9% in the presence of manure, respectively. Similar behavior was observed in the case of disturbed soil columns. Soil macro-porosity has shown large impact on atrazine transport, especially in the presence of manure.     

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Abstract

The leaching behaviour of the herbicide acetochlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(ethoxymethyl)acetamide] was determined as compared with two congener compounds, alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide]. The leaching profiles of the herbicides in columns with different types of soil and their capacity factors in reverse phase HPLC were compared. An approach for preliminary characteristic of the potential for water pollution of acetochlor is presented. The herbicide is classified as a leacher in soil and its potential for contamination of ground water is comparable with those of alachlor and metolachlor.     

Selective removal of diclofenac from contaminated water using molecularly imprinted polymer microspheres

A molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template. Binding characteristics of the MIP were evaluated using equilibrium binding experiments. Compared to the non-imprinted polymer (NIP), the MIP showed an outstanding affinity towards DFC in an aqueous solution with a binding site capacity (Q_max) of 324.8 mg/g and a dissociation constant (K_d) of 3.99 mg/L. The feasibility of removing DFC from natural water by the MIP was demonstrated by using river water spiked with DFC. Effects of pH and humic acid on the selectivity and adsorption capacity of MIP were evaluated in detail. MIP had better selectivity and higher adsorption efficiency for DFC as compared to that of powdered activated carbon (PAC). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance, which is a definite advantage over single-use activated carbon.     

Molecularly imprinted polymers for the detection of benomyl residues in water and soil samples

Benomyl is a benzimidazol fungicide used against various crop pathogens. Although banned in many countries, it is still widely used worldwide and is listed in different monitoring programs among the substances to be monitored to assess human exposure to pesticide residues. The assessment of benomyl is mainly based on the analysis of the residues of its most important metabolite, carbendazim. Existing methods often lack of selectivity and display a limited performance because of the presence of co-extracted compounds. Molecularly imprinted polymers (MIPs) offer an alternative methodology, adsorbing preferentially those target molecules for which the polymers are specifically prepared. In this study, we optimized the synthesis of a polymer imprinted with benomyl. Tests of specificity recognition showed a good performance for carbendazim compared with other similar pesticides. The mean recovery of benomyl (measured as carbendazim) from water samples was estimated to be 90% for MIPs while with real soil samples collected in Morocco the recovery efficiency was 62%. Preliminary tests also suggest that this MIP can implement traditional SPE techniques for assessing benomyl residual concentrations in environmental samples.     

杉木短柱高温烘烤后残余承载力研究

为了研究杉木短柱在高温后残余承载力,制作了一批构件,进行了高温烘烤和轴心压缩试验。通过对试验结果进行分析,研究杉木短柱炭化速度和压缩性能变化规律,探讨烘烤温度、防火漆对杉木短柱炭化速度、残余承载力的影响。试验表明,杉木短柱炭化速度随着烘烤温度的增加而增加,高温后杉木短柱的压缩曲线分为弹塑性阶段和破坏下降阶段,当荷载达到极限荷载后,曲线出现明显的下降段而发生破坏;杉木短柱残余承载力随温度升高而降低;木材防火漆能改善杉木短柱的耐火性能,降低其炭化速度和提高残余承载力。采用剩余截面法计算高温烘烤后的杉木短柱残余承载力,理论公式与实验值基本吻合。     

火灾后圆钢管约束钢筋再生混凝土轴压短柱 力学性能分析

利用ABAQUS软件建立了火灾后圆钢管约束钢筋再生混凝土轴压短柱的非线性有限元模型,在确定混凝土和钢材的本构基础上,对其火灾后剩余承载力和轴压刚度进行了数值计算,并与已有相关试验数据进行比对分析。分析了升温时间、截面直径、材料强度、骨料取代率、含钢率和配筋率等参数对火灾后剩余承载力和轴压刚度的影响规律。结果表明:升温时间和截面直径是影响火灾后试件剩余承载力和轴压刚度的主要因素;提出了该类试件火灾后剩余承载力和轴压刚度的简化计算公式,可为工程实际应用提供参考。     

双柱双ECD检测器气相色谱仪测定有机氯农药方法的研究

采用Angilent 6890N双柱双ECD检测器气相色谱仪,色谱条件为:柱1 DB-1701 30m×0.53rnm×0.83μm,柱2 DB-608 30m×0.53mm×1μm,柱温范围为150.0～270.0℃,2柱分别为5.0mL/min载气(N_2)流量,60.0mL/min尾吹气流量,采用不分流模式,建立了测定有机氯农药的分析方法。在此色谱条件下得到了较好的组分分离,2根柱可分离20个有机氯农药化合物及2个示踪剂,被分离化合物具有良好的线性(r>0.99).较好的精密度(C.V%0.47～5.21)和准确度。由于采用了双柱双ECD检测器,故该方法具有定性更准确、定量更精确的特点。同时,对各组分和示踪剂的回收率及最小检出浓度进行了研究并得到了满意的结果,对实际水样进行了测试。