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1.
利用灰色关联分析方法研究粉煤灰的粒度分布对水泥性能的影响．结果表明：O～5μm、5～10μm粉煤灰颗粒分别是水泥3d、28d抗压强度的最强影响因子;水泥3d、28d强度随小于33μm的粉煤灰颗粒含量增大而提高,随大于33pm的粉煤灰颗粒含量增大而降低;可以通过优化粉煤灰的粒度分布来改善水泥性能． 相似文献
2.
漆酚甲醛缩聚物乳液的研制 总被引：1，自引：0，他引：1
用漆酚基乳化剂（UE）将漆酚甲醛缩聚物（UFP）乳化为水包油（O／W）型的稳定水基分散体系．研究了乳化温度、UE用量及UE结构对相反转乳化过程的的影响,并用乳液体系电导率变化和黏度变化表征了相反转乳化过程．实验结果表明,以漆酚基乳化剂UEl0B为乳化剂,利用相反转技术可得到稳定的漆酚甲醛缩聚物水性乳液．当UE10B与UFP的质量比r≥10％,乳化温度为40℃时,可将漆酚甲醛缩聚物乳化为稳定的水基化分散体系．所制得漆酚甲醛缩聚物乳液粒子为多孔结构的5～20μm微球,孔的尺寸小于1μm． 相似文献
3.
This paper presents the research on the atmospheric corrosion rates of carbon steel, zinc and copper in Chongqing, which was a corrosion subprogram of an international project, Regional Air Pollution in Developing Countries. We performed field exposure tests of carbon steel, zinc and copper at an urban site Guanyinqiao and a rural site Tieshanping inChongqing, then used grey relational analysis, based on the database of the whole corrosion project, to determine the order of the effect of environmental factors on corrosion rates of tested metals, and established dose-response functions for these three metals. The results showed that the two crucial agents of acidic environment, SO2 and H , were common factors that contributed most to the corrosion of the tested metals. The established dose-response functions for outdoor carbon steel and zinc are proved applicable to use in Chongqing, but the function for copper needs further modifying. We employed these dose- response functions and general environmental data to elaborate the maps of corrosion rate respectively of carbon steel and zinc by geological information system (GIS) technique which help to identify areas of high corrosion damage risk. An acceptable annual average SO2 level of 21 μg/m3 for carbon steel and that of 61 μg/m3 for zinc are also put forward to control the air pollution impact on atmospheric corrosion in Chongqing urban areas. 相似文献
4.
INTRODUCTION Over the recent decades extensive research on atmospheric particles in urban environments was carried out. Most of the following papers refer to their authors’ contribution to air pollution and the effects on human health (Dzubay and Mamane, 1989; van Borm et al., 1989; 1990; Rojas et al., 1990; Paoletti et al., 1991; 1999; Al-Rajhi et al., 1996; McMurry et al., 1996; Querol et al., 1996; BéruBé et al., 1997; Esteve et al., 1997; Harrison et al., 1997; Zou and Hooper… 相似文献
5.
Super absorbent polymers (SAPs) are gradually being applied in concrete production as internal curing agents.SAP can effectively reduce early age autogenous shrinkage of concrete,alleviate the hazards caused by concrete cracking and improve its freeze–thaw resistance.However,the relationships between SAP dosage,SAP particle size and the water–cement ratio of concrete have certain influences on the evolution of the compressive strength of SAP-incorporated concrete.In this study,experiments were conducted to investigate the relationships between the water–cement ratio of concrete,the SAP dosage and SAP particle size.The significant factors influencing concrete strength are determined and equations are proposed for predicting the strength of SAP-incorporated concrete at 3,7 and 28 days.The findings from this study,such as the SAP dosage should not be larger than 0.2%,are expected to form a theoretical basis for the rational use of SAP as an additive to concrete. 相似文献
6.
人体呼出气溶胶在封闭环境中的分布特性 总被引：1，自引：0，他引：1
研究了1.0～10.0μm的呼吸道颗粒物在混合送风、置换送风和地板送风的办公室环境中的浓度空间分布和瞬态演变规律.仿真结果表明：小于10.0μm的飞沫在混合送风的房间内几乎是均匀分布的.然而,在置换送风和地板送风中,垂直温度梯度使得小于10.0μm的飞沫在人体呼吸区高度聚集,导致一个较高的浓度水平,因此室内人员被感染的概率比较高.由咳嗽或者打喷嚏产生的飞沫在置换和地板送风中的稀释（浓度衰减）比在混合送风中慢,这是因为置换和地板送风中人体呼吸区的风速比较小,飞沫在此聚集,不易被气流携带排出室内空间. 相似文献
7.
Different ambient conditions for the synthesis of Ag（Nb0.8Ta0.2）O3 ceramics were investi- gated. The Ag（Nb0.8Ta0.2）O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disks and sintered between 1060 ℃ and 1100 ℃ respectively. Samples were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurement. The results show that perovskite Ag（Nb0.8Ta0.2）O3 powder was easier to be synthesized in air than in vacuum at 950℃. Grain size of ceramic samples sintered in air was uniform （about 1 μm） and its dielectric loss was small for its high density. However, the samples decomposed greatly and ceramics could hardly be densified when sintered in vacuum, Thus,. higher atmospheric pressure and oxygen atmosphere would benifit the synthesis of Ag （Nb0.8Ta0.2）O3, and suppress its decomposition at high temperature. 相似文献
8.
Laser Doppler Anemometer has been used to measure the flow field characteristics near the interface around a moving bubble in the presence of ultrafine particles. In order to model a moving bubble, the bubble was fixed into the counter-flow liquid by a metal mesh. Experimental materials are air and water, and the particles are complex oxidate powder. Experiments were carried out under the operating conditions: the liquid flow velocity u0 is 12.6 cm/s, the equivalent diameter de is 0.6 cm, the mass concentration of particle is 0.2%,the average particle diameter is about 10 nm and the density is 2 g/cm3. The velocity profiles of both frontal and tail-vortex areas were measured respectively. The experimental results show that the velocity fields are obviously changed in the existence of particles. In the frontal area of the bubble, both tangential and normal velocities decrease due to the presence of particles, but in tail vortex area, the tangential velocities increase remarkably, and normal velocities rise gradually from the center towards the fringe in the opposite tendency to that of no particles. The influences of flow field change in the presence of particles on gas-liquid mass transfer are analyzed and discussed. 相似文献
9.
根据乐山大佛景区环境空气质量监测数据,分析了二氧化硫(SO2)、二氧化氮(NO2)、可吸入颗粒物(PM10)3种污染物的时间变化规律及污染特征.结果表明:乐山大佛景区环境空气质量相对较好,优良率在87%以上,可吸入颗粒物浓度值在低浓度水平的基础上有上升的变化趋势,达到现行国家环境空气质量标准,二氧化硫、二氧化氮的污染总体上变化不显著. 相似文献
10.
Li-qiang Su Jia-guo Li Hua Xue Xiao-feng Wang 《Journal of Zhejiang University. Science. B》2017,18(8):696-706
Coating seeds with water absorbent materials can improve their survival, especially for those planted in drought or barren areas. In this study, effects of five kinds of super absorbent polymers (SAPs) on seed germination and seedling growth of Caragana korshinskii under drought conditions were investigated. Our results showed that SAP coatings could significantly improve the percentage and energy of seed germination, as well as reduce the relative electrical conductivity (REC), proline, malondialdehyde (MDA), H2O2 content, and peroxidase (POD) activity during germination. These results implied that seeds could uptake moisture from SAP coatings to alleviate drought-induced oxidative stress and membrane damage, thus exhibiting a better vigor and germination performance. After coating C. korshinskii seeds with SAPs, more seedlings emerged and grew better. Under the combined influence of the water absorption capacity of SAP and other factors, the efficiencies of five SAP coatings are in the sequence D>E>B>A>C. The function of the SAP coating on promoting seedling survival was confirmed in Mu Us Sandy Land in Ordos, Inner Mongolia Autonomous Region, China. The average seedling number of SAP D-coated seeds increased twofold on that of naked seeds. Our results are expected to be helpful in understanding and utilizing SAP seed coatings in improving plant survival under drought conditions. 相似文献
11.
遂宁市大气主要污染物污染水平及变化规律 总被引：2，自引：0，他引：2
根据遂宁市2006年1月1日至2010年12月31日的环境监测数据,采用API指数法分析和评价了遂宁市大气中污染物变化规律.结果表明：各功能区的PM10的日平均浓度为0.077－0.123 mg/m^3,二氧化硫为0.030－0.043 mg/m^3,二氧化氮为0.022－0.025 mg/m^3,空气污染指数小于100.在时间变化规律上,各功能区PM10污染总体表现为第一季度污染相对稍重,其次为第二季度,再次为第四季度,第三季度污染较轻.在空间变化规律性上,以城南（群康印染厂）工业区污染稍重,次之为城西（监测站）片区,河东新区（市行政中心）环境质量最好.提示遂宁市可吸入颗粒物为空气中的主要污染物. 相似文献
12.
Sheng-chun DANG Yan-hua ZENG Ping-jiang WANG Bao-ding CHEN Rong-fang CHEN Arun KUMAR SINGH Pankaj KUMAR Shu FENG Lei CUI Hao WANG Jian-xin ZHANG 《Journal of Zhejiang University. Science. B》2014,15(6):556-565
Background and objective
It has been shown that macrophages play an important role in the development of severe acute pancreatitis (SAP), and eventually lead to multiple organ failure (MOF). Clodronate-liposome selectively depleted macrophages. This study was to investigate the role of renal macrophage infiltration in acute renal injury in rats with SAP and to evaluate the potential of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) for diagnosis.Methods
Superparamagnetic Fe3O4 nanoparticles were prepared by chemical coprecipitation. SPIO-liposomes and SPIO-clodronate-liposomes were prepared by the thin film method. SAP models were prepared by injection of sodium taurocholate into the subcapsular space of rat pancreas. Sprague-Dawley rats were randomly divided into a control group, SAP plus SPIO-liposome (P) group, and SAP plus SPIO-clodronate-containing liposome (T) group. Kidney injury was evaluated by T2-weighted MRI scan. The levels of serum amylase (SAM), blood urea nitrogen (BUN), and serum creatinine (SCr) were measured by an automated enzymatic method. Serum tumor necrosis factor-α (TNF-α) was measured by enzyme-linked immunosorbent assay (ELISA). Pathological changes in the pancreas and kidney were observed using hematoxylin and eosin (H&E) staining, while cell apoptosis was detected with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. In addition, the macrophage markers (CD68) of the renal tissue were detected with immunohistochemistry.Results
The pathological changes in the pancreas and kidneys of rats in the T group were milder than those in the P group. The MRI signal intensity of the kidneys in the P and T groups was significantly lower than that in the control group. There were significant changes in the two experimental groups (P<0.01). The levels of SAM, Bun, SCr, and TNF-α in rats in the P group were higher than those in the control group (P<0.01) and in the T group (P<0.01). The apoptosis of the kidney in the T group was higher than that in the P group at 2 and 6 h (P<0.01).Conclusions
Clodronate-containing liposomes protected against renal injury in SAP rats, and SPIO can be used as a tracer for MRI examination to detect renal injury in SAP rats. SPIO-aided MRI provided an efficient non-invasive way to monitor the migration of macrophages after renal injury in rats with SAP. 相似文献13.
Irradiated by infrared laser, the surface reducibility and adsorbability of Cu-Cr complex could be improved, owing to the interaction of photo-fragmentation and laser texturing. Analyzed by the binding energy spectra and the auger spectra, the valence states of chromium ion and copper ion were+3 and+1 after radiation respectively, which still had the reducibility to release electrons. In contrast with the near-infrared(NIR)1 064 nm and mid-infrared(MIR) 10 600 nm laser at the same average output power of 15 W, the reduced metal percentage in the Cu-Cr complex was obviously distinguished at the depth from nanometer to micron. After chemical plating, the average coating thickness and mean-square deviation of the NIR sample were 11.61 μm and 0.30 for copper layer, and 2.69 μm and 0.08 for nickel layer. The results were much better than those of the MIR sample. 相似文献
14.
YANG Ying TONG Mingwei WU Zhijuan College of Power Engineering Chongqing University Chongqing P. R. China 《重庆大学学报(英文版)》2004,3(1):6-10
1.IntroductionTherequirementsforenvironmentalprotectionaregettingstricterworldwide.Notonlythenaturalecologyandresourcesshouldbeconsideredinconservation,butalsotheenvironmentbeprotectedfrombeingsacrificedastheexpenseofproductivityboosts.Aconventionalmachiningprocessusedtotakeoilasthelubricantandcoolantforthesurfacesofmachinedtoolsandworkpieces,whichbroughtforthenvironmentpollution,andincreasedcostsonpost-treatingoftools,workpiecesandcuttingscrap.Asaresult,greenmachiningtechnologyfeaturingcleanp… 相似文献
15.
赵国求 《武汉工程职业技术学院学报》1997,(1)
传递弱作用的规范粒子是有质量的,有质量的粒子在相互作用中要做加速运动,建在其上的坐标系是加速系,时空不均匀、不对称.在弱电统一理论中,希格斯机制的实质是提供一个时空的事先破缺,并让其与传递弱作用的规范粒子带进的时空破缺性质相反,两者刚好相互抵消,使真空保持均匀对称性.这样的时空系统可以保证拉格朗日密度不变,相对性原理成立. 相似文献
16.
Indoor environment separated with down.feed air curtain was numerically simulated and experimentally researched.Indoor airflow and temperature fields separated with air curtain were numerically simulated.Resuits show that both polluted airflow and thermal air current can be separated with a down.feed air curtain to prevent contaminants from spreading in the room space.In a test chamber.the smoke of burning Tibetan incense served as the source of contaminants.and the probe test shows that 1.0 pm is the prevailing diameter of the smoke particles.During the release of the smoke.the particle concentration of the indoor air was tested with a laser particle counter at the points of three different heights from the floor when the air curtain was running or not.Experimental results show that the higher the test point is located,the lower the particle concentration is,implying that the separating or isolating eflfect decreases as the air velocity of the curtain reduces along with the height descends.According to both simulation and experimental results.down.feed air curtain can separate indoor environment effectively when the supply air velocity of air curtain is not less than 3 m/s.In order to strengthen separation effect,it is suggested that the supply air velocity be speeded up to 5 m/s. 相似文献
17.
张力 《遵义师范学院学报》2004,6(4):36-37
僰人并不是一种少数民族,而是自西周以来被发配到西南边疆的流放罪犯的后裔.明末清初,天下大乱,四川为祸甚烈,僰人为躲避祸乱,化整为零,从他们的聚居地散避出来,分布于现今的川南,黔北,滇东一带.悬棺葬是为了防止野兽掘坟啮尸的一种无可奈何的安葬方法. 相似文献
18.
Qing-yu Zhang Guo-jin Sun Wei-li Tian Yu-mei Wei Si-mai Fang Jin-feng Ruan Guo-rong Shan Yao Shi 《浙江大学学报(A卷英文版)》2011,12(9):702-709
This paper deals with a mortality-weighted synthetic evaluation (MWSE) method for evaluating urban air risk. Sulphur dioxide
(SO2), nitrogen oxide (NO
x
), and particulate matter (PM10) were used as pollution indices. The urban area of Hangzhou, China is divided into 756 grid cells, with a resolution of 1
km×1 km, and is evaluated using the MWSE and the air quality index (AQI), a widely-used method to evaluate ambient air quality
and air risk. In an evaluation of one day in April 2004, the surface areas categorized as levels I and III, as defined by
the integrated air risk evaluation, were 27.3% and 3.3% lower, respectively, than grades I and III defined by the AQI evaluation.
Meanwhile, the areas classified as level II or above level III by the integrated air risk evaluation were 55.1% and 101.1%
higher, respectively, than grade II or above grade III when using the AQI evaluation. From this comparison, we find that the
MWSE method is more sensitive than the AQI method. The AQI method uses a single index to assess integrated air quality and
is therefore unable to evaluate integrated air risks due to multiple pollutants. The MWSE method overcomes this problem, providing
improved accuracy in air risk assessment. 相似文献
19.
陈晓英 《天津职业院校联合学报》2007,9(2):3-5
在中央空调系统中,经大型喷水室处理后的空气在通过挡水板后,总有一些悬浮在空气中的小水滴,未能被挡水板挡去(分离出去),这些水滴随着空气进入风道进入空调房间。这种现象本是不应出现的,水滴会使风道锈蚀,也会使风口处的设备锈蚀,减少了风道及设备的寿命,在这些缺点的背后,还带来了其他的影响。 相似文献
20.
The distribution and characteristics of nonmetallic micro-inclusions of GCrI5 bearing steel were explored through metallographic area method in virtue of tracer method and electronic microscope.The results show that the micro-inclusions,of which the average value is 0.032%,are mainly the compounds formed via the adsorption/aggregation of multielement deoxidized compounds and secondarily deoxidized products on tundish liquid level.The micro-inclusions of diameters from 0 to 5 μm are 92.5% in total,which basically determines the characteristics of inclusions distribution in casting slab.The inclusions of diameters more than 10 μm only account for less than 1% in total,which have little influence on steel quality.The relationship between equilibrium compositions of the first deoxidation products and molten steel compositions was also calculated based on thermodynamic theory. 相似文献