近断层地震动特性研究综述

由于近断层地震动对结构的影响比普通地震动的影响大,近断层地震动特性及其影响引起各国学者的广泛关注。通过对近断层地震动的定义与近断层地震动的脉冲特性等相关研究进行归纳总结,梳理近断层地震动对结构地震需求及抗震性能的影响,明确近断层地震动在结构抗震分析中的模拟方法及关键问题。     

不同震源机制的近断层脉冲型地震动频谱特性及强度指标研究

将不同场地类别和震源机制上的118条近断层地震记录进行分类,基于基础隔震结构的双自由度体系简化模型,利用状态空间法及四阶龙格-库塔法对结构的弹塑性反应谱进行求解,研究了场地类别和震源机制对反应谱频谱特性的影响。通过分析近断层地震记录的3个强度指标与基础隔震结构最大弹塑性响应的相关性,探讨了基础隔震结构地震反应分析时强度指标的选取问题。结果表明,三种场地类别条件中,速度反应谱规律不明显,但逆断层地震动的平均加速度反应谱和逆斜断层地震动的平均位移反应谱均最大。场地类别和震源机制不同,地震动强度指标与结构响应的相关程度不同。因此在进行近断层脉冲型地震动作用下基础隔震结构地震反应分析时,建议考虑结构所在场地及地震动的震源机制后采用不同地震动强度指标来选择和调整地震动输入。     

近断层/远场地震动作用下隧道结构易损性研究

以川藏铁路线控制性工程——折多山隧道为研究对象,建立隧道动力时程分析模型.结合场地地震动设计反应谱,选取近断层脉冲型地震动及远场地震动记录,用于增量动力分析隧道工程结构的抗震性能水平.初步探讨适用于隧道结构的地震动强度指标IM,分析不同特征部位隧道结构易损性,对比分析近断层脉冲型地震动及远场地震动作用下隧道结构的地震易...     

硫酸酯化牡蛎多糖对四氯化碳所致小鼠急性肝损伤的影响

为研究硫酸酯化牡蛎多糖(SCGP)对四氯化碳(CCl4)所致小鼠肝损伤的影响,采用氯磺酸-吡啶法制备得到SCGP,对CCl4致急性肝损伤模型小鼠灌胃不同剂量(200、400、800 mg/kg)的SCGP,并设对照组、模型组(灌胃生理盐水)和药物组(灌胃联苯双酯,200 mg/kg),各组连续灌胃14 d,然后给模型组、药物组和SCGP组腹腔注射CCl_4致病,18 h后处死小鼠,测定各组小鼠血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)活性和肝组织匀浆中超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量,观察小鼠肝组织切片形态学变化和SCGP对小鼠急性肝损伤的影响。结果表明:小鼠肝组织切片在倒置显微镜下显示,SCGP灌胃组和药物组肝细胞病变较模型组明显减少;SCGP高剂量组(800 mg/kg)能显著降低CCl4致急性肝损伤小鼠的血清ALT、AST活性和肝脏MDA含量(P<0.05),显著提高小鼠肝脏的SOD活性(P<0.05)。研究表明,SCGP对经腹腔注射CCl4所致的小鼠肝损伤可起到保护作用。     

Assessing the human health risks from exposure of inorganic arsenic through oyster (Crassostrea gigas) consumption in Taiwan

This study estimated the human health risk associated with ingesting inorganic arsenic through consumption of farmed oysters in Taiwan. Two hundred fifty-four samples of oyster (Crassostrea gigas) were collected from four townships in southwest coastal areas, where 90% of Taiwan's oysters are produced. The concentrations of total arsenic and arsenic species including As(V), As(III), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were analyzed. The analytical results reveal that the ratio of mean concentration among the four townships of inorganic As to total concentration of As in oysters is approximately 1.64%. The mean concentrations of As(III) and As(V) in oysters from the four townships range from 0.071 to 0.145 microg/g, and 0.032 to 0.062 microg/g respectively. The estimated target cancer risks (TR), based on a 95% occurrence probability from ingesting inorganic As by consuming oysters at a rate of 18.6-56 g/day, range from 1.26 x 10(-5) to 3.82 x 10(-5). The probabilities of TR fell within the range 10(-6)-10(-4), suggesting that inorganic As uptake from farmed oysters is associated with a potential cancer risk. Moreover, a target hazard quotient (THQ) was used to evaluate the non-carcinogenic risk associated with ingesting inorganic As through oyster consumption at a rate of 18.6-56 g/day. The THQ values based on a 95% probability of exposure range from 0.071 to 0.214. All THQ values are below unity, indicating that farmed oyster consumption contributes only a little to the non-carcinogenic risk. Based on the estimation of the TR model, an ingestion rate of 1.6 g/day is recommended to meet the 95th percentile of carcinogenic risk, 10(-6), for exposure to inorganic As through the consumption of oysters in Taiwan.     

柠檬酸钠促进S-腺苷蛋氨酸和谷胱甘肽联合高产

考察了柠檬酸钠对S-腺苷蛋氨酸(SAM)和谷胱甘肽(GSH)联产发酵的影响,发现柠檬酸钠有利于SAM和GSH的联合高产。采用响应面分析法对柠檬酸钠浓度及其添加时间进行优化,模型预测和验证实验结果均表明在联产发酵6 h时一次性添加10 g/L柠檬酸钠的效果最佳。通过对SAM和GSH联产发酵过程进行分析,发现柠檬酸钠能够显著提高胞内NADH和ATP的水平,为SAM和GSH的过量合成提供了足够的能量物质,也为类似耗能化合物的生物合成及其发酵高产提供了可行的优化策略。     

Removal of heavy metals from electroplating rinsewaters by precipitation, flocculation and ultrafiltration

Chromium, nickel, copper and zinc can be effectively removed from electroplating rinsewaters by hydroxide precipitation, flocculation and ultrafiltration. Prior to precipitation, chromium is reduced from the hexavalent to the trivalent form by ferrous sulfate and cyanide in copper and zinc rinsewaters are oxidized by sodium hypochlorite. Minimum metal concentrations in the permeate from separate batches of chromium, nickel, copper and zinc rinsewaters were found to be, respectively, 0.17 mg 1⁻¹ Cr (T), 0.26 mg 1⁻¹ Ni, 0.30 mg 1⁻¹ Cu and 1.84 mg 1⁻¹ Zn. These solubilities are in good agreement with the theoretical solubility curves, except for copper where the formation of stable copper cyanide complexes appears to increase the solubilities at least two orders of magnitude relative to those predicted on the basis of the equilibrium constants for copper hydroxides and oxides. A simple mass balance model, assuming concentrate recycle and constant metal concentration in the permeate, is adequate for the prediction of feed and permeate concentrations as a function of the volume filtered up to a relative volume of about 0.3. Above this value, the feed concentrations are lower than predicted, apparently because of entrapment of metal precipitate in the strainer. Water recoveries are strongly dependent on the specific metal removed and are found to be 24% for Ni with a 0.20 μm membrane, 10% for Cr with a 0.80 μm membrane, 6.5% for Cu and 3.7% for Zn, both with a 0.45 μm membrane.     

Water recovery from treated urban wastewater by ultrafiltration and reverse osmosis for landscape irrigation

Techno-economic feasibility of water recovery from secondary effluents of an urban wastewater treatment plant (WWTP) for landscape irrigation was investigated considering two distinctive strategies: ultrafiltration (UF)/chlorination and UF/reverse osmosis (RO). Experimental performance evaluations were conducted separately for UF membranes and for different RO trans-membrane pressures. The quality of the effluent recovered by the UF/RO system was in accordance with the national and international guidelines. The produced reuse water was first class quality according to the national guideline for all parameters except sodium adsorption ratio (SAR), which can be eliminated readily by direct addition of KCl into the recovered water. Estimated field-scale costs indicated that UF/RO yielded a total cost of US$12,500,000–13,600,000 with annual operating cost being US$482,000–533,000 at 5–20 bar. The economic estimations guaranteed reimbursement with US$7,600,000–7,400,000 net present value, 0.22–0.39 year payback time, US$0.44–0.49/m³ treatment cost, and a benefit/cost ratio of 0.57.     

Removal of uranium from waters with the various salt content by the ultrafiltration method

We have investigated the impact of various salt content of waters being purified on regularities of ultrafiltration only and ultrafiltration combined with complexation of water purification of waters contaminated with U(VI). The uranium detention coefficient of the membranes used in the course of investigation reached the values 0.90–0.999.     

低环境负荷型功能胶凝材料的制备与性能

采用50%以上的钢渣、矿渣、粉煤灰等工业废渣与52.5PI.I水泥复合制备3种低环境负荷型强度等级42.5的特种水泥,同时全部采用废渣制备新型膨胀剂WUT,低热水泥3d、7d水化热分别比42.5PO.水泥下降27%和36%,达到GB200—89对低热42.5级水泥的要求,化学收缩显著降低,在37℃环境中经1.5h的流动度损失小于4cm;经抗硫酸盐侵蚀和抗海水侵蚀试验,水泥的抗硫酸盐侵蚀作用显著;膨胀剂WUT比一般膨胀剂早期膨胀值低,但后期膨胀持续时间长。     

混凝沉淀超滤组合工艺净化地表水的研究

结合水厂现有工艺,采用混凝沉淀超滤组合工艺处理北方地表水,为新建水厂以及现有水厂的改造提供技术储备。研究结果表明:超滤对浊度、细菌、大肠菌和总铁有很好的去除效果,但对有机物的去除效果有限,且能去除的主要为分子量30 ku的有机物。根据现有条件进行经济分析得出,超滤单元的最高处理成本为0.27元/m3。     

含多种侧链官能团共聚羧酸与萘磺酸甲醛缩合物复合高效减水剂的制备与性能

采用分子设计方法合成了含多种侧链官能团共聚羧酸(CoPoCa-300)外加剂,与萘磺酸甲醛缩合物复配得到一系列新的复合型高效减水剂CoPoCa-NSF系列.复合型高效减水剂降低了萘系减水剂用量,并且产生超叠加效应使复合减水剂具有较高的减水率(24%～28%)和良好的坍落度保持性,可显著提高混凝土的强度40%～50%.     

火灾中的热对人身和财产的危害

在烃类液体火灾（油池火）或蒸气与空气混合燃烧的火灾（蒸气火,vapor fire）中,来自火焰的辐射热（即热辐射）,增加了对火灾以外区域人员和财产的危害。