Asphalt stripping bacteria

A study of asphaltic pavements ranging in age from 3 to 42 years, taken from several locations in the State of Kansas (USA) revealed that bacteria belonging to the family Pseudomonadaceae and the genus Thiobacillus appear to play an important role in the deterioration of asphaltic materials. The pinhole effect on the stripping of asphalt from aggregate surface is described alongside the synergistic effect of moisture and bacteria on asphalt deterioration.     

Assembly of asphaltene molecular aggregates as studied by near-UV/visible spectroscopy: II. Concentration dependencies of absorptivities

The properties of molecular aggregation in toluene solutions of a crude oil and solid asphaltenes are determined almost solely by the concentration of asphaltenes, as shown by absorptivity measurements at 315–750 nm. From non-monotonic concentration dependencies of absorptivities, it is concluded that asphaltene monomers are abundant in solutions with asphaltene concentrations below 1–5 mg/l, while molecular aggregates are effectively formed above 20–25 mg/l. The most stable oligomers are a dimer and a dimer pair (Yen's “nanocrystallite” [NC]). Nanocrystallites act as building blocks for more complex aggregates at asphaltene concentrations exceeding 90–100 mg/l. These optical absorption results are supported by studies of Rayleigh scattering in asphaltene solutions.     

Quantifying Rainfall and Flooding Impacts on Groundwater Levels in Irrigation Areas: GIS Approach

Landscapes continuously irrigated without proper drainage for a long period of time frequently experience a rise in water-table levels. Waterlogging and salinization of irrigated areas are immediate impacts of this situation in arid areas, especially when groundwater salinity is high. Flooding and heavy rainfall further recharge groundwater and accelerate these impacts. An understanding of regional groundwater dynamics is required to implement land and water management strategies. The purpose of this study is to quantify the impact of flood and rain events on spatial scales using a geographic information system (GIS). This paper presents a case study of shallow water-table levels and salinity problems in the Wakool irrigation district located in the Murray irrigation area with groundwater average electrical conductivity greater than 25,000?μS/cm. This area has experienced several large flood events during the past several decades. Piezometric data are interpolated to generate a water-table surface for each event by applying the Kriging method of spatial interpolation using the linear variogram model. Spatial and temporal analysis of major flood events over the last four decades is conducted using calculated water-table surfaces to quantify the change in groundwater storage and shallow water-table levels. The drainage impact of a subsurface drainage scheme partially covering the area has also been quantified in this paper. The results show that flooding and local rainfall have a significant impact on shallow groundwater. The study also found that postflood climatic conditions (evaporation and rainfall) play a significant role in the groundwater dynamics of the area. The spatial net average groundwater recharge during the flooding events ranges from 0.19 to 0.52?ML/ha. The GIS-based techniques described in this paper can be used for net recharge estimation in semiarid regions where it is important to quantify net recharge impacts of regional flooding and local rainfall. The spatial visualization of the net recharge in a GIS environment can help prioritize management actions by local communities.     

半花菁LB多层膜二次谐波产生的温度特性研究

利用吸收谱和二次谐波产生 (SHG)技术研究了温度对半花菁Langmuir Blodgett(LB)多层膜的膜结构和非线性光学特性的影响。LB膜的二次谐波强度起初随温度的增加而增加 ,最大值约在 45℃左右 ,然后随温度的增加而减小。在半花菁与花生酸或花生酸铬交替的LB多层膜中 ,由于花生酸的融化 ,导致膜结构的变化 ,使得二次谐波强度随温度的变化有一个突变点。线性吸收谱表明半花菁分子在LB多层膜中形成了H 聚集体 ,并且通过加热可以使聚集体分解     

降低二氧化钛粗粒子数目的研究

用常规干燥、真空干燥及超临界干燥等方法研究了二氧化钛粗粒子的形成机理。结果表明 ,二氧化钛表面羟基间的脱水反应是形成二氧化钛粗粒子的原因 ,只有通过表面处理把羟基屏蔽起来或用超临界的方法防止干燥时的毛细孔塌陷才能有效地避免二氧化钛粗粒子的生成。对于已生成的二氧化钛粗粒子 ,用不同的加工设备研究了消除二氧化钛粗粒子的方法 ,结果表明砂磨的方法最佳。     

Spherical granular structures of Ag/Co nanoparticles: Synthesis, characterization and magnetic properties

Ag/Co bimetallic nanoparticles in the form of hierarchical spherical structures were prepared by the polyol process using oleic acid and oleylamine as surfactants. The Ag/Co nanoparticles so obtained were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), UV-vis spectroscopy (UV-Vis), small angle X-ray scattering (SAXS), vibrating sample magnetometer (VSM) and super-conducting quantum interference device (SQUID). The XRD results in complement with the UV-vis studies indicated the absence of Ag-Co alloy formation during the synthesis. The FESEM observations depicted dense and uniform spherical granular structures for the Ag/Co nanoparticles; while the TEM studies apparently revealed a bimodal distribution of nanoparticles exist in the Ag/Co samples. The SAXS analysis on the Ag/Co colloids further validated the TEM results. The VSM studies showed typical ferromagnetic characteristics for the Ag/Co nanoparticles at room temperature; whereas the SQUID measurements demonstrated superparamagnetic nature for these nanoclusters with a blocking temperature close to 250 K. The synthetic route presented in this work represents a simple means of producing bimetallic composite superstructures of Ag/Co nanoparticles in the form of spherical granules on a large scale. These spherical aggregates have the potential to be important building blocks for more complex nanostructures and would be interesting for magnetic studies and catalytic applications.     

Post-fire mechanical performance of concrete made with selected plastic waste aggregates

This paper presents an experimental study about the effects of elevated temperatures on the residual mechanical properties of concrete incorporating selected plastic waste aggregates (PWAs). Six different concrete mixes were prepared: a reference concrete (RC) made with natural aggregates (NAs) and five concrete mixes with replacement ratios of 7.5% and 15% of natural aggregate by three types of polyethylene terephthalate (PET) plastic waste aggregate (CPWA). Specimens were exposed to temperatures of 600 °C and 800 °C for a period of 1 h, after being heated in accordance with the ISO 834 time–temperature curve. After cooling down to ambient temperature, the following properties were evaluated and compared with reference values obtained prior to fire exposure: (i) compressive and (ii) splitting tensile strengths, (iii) elastic modulus, (iv) ultrasonic pulse velocity (UPV), (v) surface hardness, and (vi) water absorption by immersion. For the replacement ratios used in these experiments, the maximum temperatures reached in CPWA were higher than those measured in RC, due to the higher porosity increase with temperature of the former type of concrete that facilitated the propagation of heat inside concrete, and the exothermic thermal decomposition of plastic aggregates that generated additional heat. After exposure to elevated temperatures, the degradation of compressive strength and elastic modulus of CPWA was higher than that of RC, particularly for the highest replacement ratio, as a consequence of the higher porosity increase experienced by CPWA. The reduction of residual splitting tensile strength of CPWA was found to be similar to that of RC, possibly because the incorporation of PWA led to lower internal stresses due to thermal gradients and allowed an easier dispersion of gases confined in pores, thus reducing crack development in the matrix. The magnitude of the degradation of concrete’s residual mechanical properties was seen to depend on the type of PWAs and the replacement ratio. The residual compressive strength of CPWA proved to be strongly correlated with both UPV and water absorption by immersion, but its correlation with surface hardness was less significant.     

Environmental effects of coal gangue and its utilization

Coal gangue has accumulated huge coal gangue piles, occupying lots of land as well as having striking influence on the neighboring environmental effects. This paper seeks a new way of coal gangue treatment in which the coal gangue blended with shale and sludge was sintered in rotary kiln to form lightweight aggregates. The results show that the optimum mixture ratio of coal gangue, shale, and sludge is 50, 40, and 10 wt% and the corresponding indicators of aggregates obtained are: (a) bulk density of 658 kg/m³, (b) granule strength of 643N, (c) 1 h absorption water to be 13.8%.     

The effect of ethoxylated nonyl phenols on viscosity of crude oil

In this study, viscosities of different crude oils was determined in the temperature range of (298–373 K) in presence of ethoxylated nonyl phenols as nonionic surfactant with ethoxy group numbers 4 and 9 (nonyl phenol 4 and nonyl phenol 9). Viscosity was measured using Viscolab PVT viscometer. Viscosity of crude oil decreased with the increase of concentration in the range of 0–1.4 g l^?1). The most radical change was observed in the presence of nonyl phenol 9. For both surfactants, the viscosities of crude oil decreased with the increase of temperature, but the effect of temperature on the viscosity of crude oil decreased when surfactant concentration increased. Because of the formation of mixed micellar aggregates, the effect of mixed surfactants on the reduction of viscosity was more obvious than individual surfactant, but mixed surfactants had very little sensitivity to the temperature than individual surfactant. The best mixture of two surfactants system was observed in the mass ratio of 3 for nonyl phenol 9 and nonyl phenol 4.