环境升温过程对常温固化环氧树脂热力学性能的影响

目的提高常温固化环氧树脂体系的高温使用性能。方法采用常温固化剂T31、中温固化剂IPDA以及高温固化剂DDM作为混合固化剂,对E-44型和AG-80型混合环氧树脂体系进行常温固化反应,并分析环境升温过程对固化物热力学性能的影响。通过DMA分析、热变形测量、固化度测试,分别评价室温固化环氧树脂在环境升温过程前后的玻璃化转变温度、热变形量及体系内部的固化反应程度变化,并通过吸水率测试和弯曲强度测试对玻璃纤维布增强常温固化环氧树脂基复合材料的耐湿热性能以及高温条件下的力学性能进行分析。结果环氧树脂常温固化物的tg为85.21℃,经1.5℃/min的平均升温速率加热至90℃之后,该环境升温过程使固化物的固化度增大至92%以上,tg增长为132.06℃的同时热变形温度增大。其复合材料耐湿热性能提高,且100℃时弯曲强度的保持率为65%,对于加热至120℃的环境升温过程,固化物的固化度接近96%,tg增长为144.45℃的同时热变形温度进一步提高,其复合材料耐湿热性能改善程度更加明显,且130℃时弯曲强度保持率仍接近60%。结论常温、中温、高温混合固化剂的合理复配有助于环氧树脂体系在环境升温变化的诱导条件下发生梯度式固化反应,使体系内部的交联固化程度迅速升至较高水平,可以有效提高其玻璃化转变温度,显著改善常温固化环氧树脂体系在高温条件下的热力学性能。     

Application of the benthic index of biotic integrity to environmental monitoring in Chesapeake Bay

The Chesapeake Bay benthic index of biotic integrity (B-IBI) was developed to assess benthic community health and environmental quality in Chesapeake Bay. The B-IBI provides Chesapeake Bay monitoring programs with a uniform tool with which to characterize bay-wide benthic community condition and assess the health of the Bay. A probability-based design permits unbiased annual estimates of areal degradation within the Chesapeake Bay and its tributaries with quantifiable precision. However, of greatest interest to managers is the identification of problem areas most in need of restoration. Here we apply the B-IBI to benthic data collected in the Bay since 1994 to assess benthic community degradation by Chesapeake Bay Program segment and water depth. We used a new B-IBI classification system that improves the reliability of the estimates of degradation. Estimates were produced for 67 Chesapeake Bay Program segments. Greatest degradation was found in areas that are known to experience hypoxia or show toxic contamination, such as the mesohaline portion of the Potomac River, the Patapsco River, and the Maryland mainstem. Logistic regression models revealed increased probability of degraded benthos with depth for the lower Potomac River, Patapsco River, Nanticoke River, lower York River, and the Maryland mainstem. Our assessment of degradation by segment and water depth provided greater resolution of relative condition than previously available, and helped define the extent of degradation in Chesapeake Bay.     

The importance of temperature in assessing iron pipe corrosion in water distribution systems

Temperature is expected to play a significant role in the corrosion of iron pipes in drinking water distribution systems. Temperature impacts many parameters that are critical to pipe corrosion including biological activity, physical properties of the solution, thermodynamic and physical properties of corrosion scale, and chemical rates. Moreover, variations in temperature and temperature gradients may give rise to new corrosion phenomena worthy of consideration by water treatment personnel.     

A study on the orbit of air temperature movement

In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view, air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful model for air temperature analysis.     

MBBR处理低浓度污水的工程应用

用 2座体积 12 0m3的移动床生物膜反应器处理抚顺乙烯有限公司厂区的低浓度 (CODCr6 0～ 80mg L)生活污水 ,停留时间 2 4h ,出水通过高效纤维球过滤罐 ,CODCr降至 2 0mg L ,BOD5降至 5mg L ,SS降至 5mg L ,氨氮降至 1mg L ,达到了循环冷却水的回用标准。进水浓度过低 ,对MBBR挂膜不利 ,工程中采用外加营养物质的措施后 ,3d内反应器成功挂膜启动。     

厌氧处理原理及其在低浓度有机废水处理中的应用现状

介绍了厌氧处理原理，并对厌氧处理低浓度废水的最新进展进行了较全面的综速，高效厌氧反应器及组合工艺为这一发展提供了可能。高效厌氧反应器中以膨胀颗粒污泥床（ECSB）反应器为首选。其结构及远行特性决定了它在处理低浓度虚水方面具有潜在的优势，但中国EC,SB的应用仅处于研究阶段，尚未有生产规模的EGSB；组合工艺对低浓度废水中污染物去除率极高，出水中COD、NH3-N、TP和SS浓度均可达到较高的排放标准，对生活污水、稀释后的工业有机废水等低浓度有机废水处理具有广阔的前景。     

唐钢2×150t转炉煤气回收系统设计及运行实践

在此较详细地介绍了唐钢一炼钢厂 2× 15 0t转炉煤气回收湿法除尘工艺和系统的技术特点。该系统设计吸收了国内外大型转炉煤气回收的经验。经近 18个月的生产实践 ;认为效果良好 ,煤气回收率近 80 % ,热值近 80 0 0kJ Nm3,放散排放浓度小于 80mg m     

植物多酚物质原位钝化污染土壤重金属的研究Ⅱ.对土壤Cu环境行为和生物活性的影响动态

通过室内好气培养和生物盆栽试验研究了缩合类植物多酚L和Y以及 8 羟基喹啉在污染红壤和潮土中的降解动态及其对土壤Cu环境行为的影响 .结果表明植物多酚在两周内降解相对较快 ,而 8 羟基喹啉则难以降解 .与空白相比 ,Cu污染土壤中施用植物多酚后土壤水溶性Cu显著下降 ,钝化Cu的效果次序为 :8 羟基喹啉 >多酚Y >多酚L .随着植物多酚的降解 ,土壤Cu被释出 ,其水溶性Cu浓度与残留在土壤中多酚浓度 (以DOC浓度表示 )呈负相关关系 ,尤其在潮土上更为明显 ,而pH与水溶性Cu没有相关性 .试验还发现 ,钝化剂施用后 ,小麦体内的Cu含量降低 ,因此 ,植物多酚是钝化重金属污染土壤的良好选择     

克山病病区低硒粮喂养的豚鼠红细胞内Na~+浓度变化的研究

豚鼠分别喂以克山病病区粮(低硒)和非病区粮(硒含量正常),借助合成的D_Y(PPP)_2~(-7)位移试剂用XL-400NMR谱仪直接测试完整红细胞内Na~+的NMR谱,并定量计算细胞内Na~+浓度,发现低硒的病区粮饲养的豚鼠红细胞内Na~+浓度显著高于正常组;病区粮喂养的豚鼠红细胞在老化条件下细胞溶血比非病区严重。     

河流枯水流量特征研究

本文以泾、洛、渭三河流干流在陕西境内的主要控制断面为例,分析了１４个时段枯水流量的概率分布特征,选定了理论分布线型,揭示了各枯水序列的时段平均流量均值、变差系数和偏态系数的变化规律,建立了推求不同频率不同时段的枯水流量的经验公式。绘制了相应的关系曲线,应用十分方便。