Removal of Dissolved- and Free-Phase Benzene Pools from Ground Water Using In Situ Air Sparging

This paper presents the results of a laboratory investigation performed to study the use of air sparging to remediate dissolved-phase and free-phase [or non-aqueous-phase liquid (NAPL)-phase] benzene pools from ground water. The specific objectives of the study were (1) to assess how air injection rate affects the mass transfer and transport of dissolved- and NAPL-phase pools; and (2) to determine the effect of ground-water flow on the removal of dissolved- and NAPL-phase pools during the application of air sparging. A total of five 2D physical model tests were performed in a homogeneous coarse sand profile subjected to both static ground water and ground-water flow conditions. Three different air injection rates were used in a static ground-water condition, and two different air flow rates were used in soil profiles subjected to ground-water flow (hydraulic gradient = 0.011). All tests were performed with similar initial dissolved- and NAPL-phase benzene conditions. Injected air traveled within a parabolic zone of influence (in channel mode) when subjected to both static ground water and ground-water flow conditions, indicating that ground-water flow (for the ground-water velocities tested) did not affect the injected air zone of influence. An increase in air injection rate led to faster contaminant removal; however, at higher air injection rates, a threshold rate of removal was reached above which further increases in injection rate are a waste of effort. Additionally, air injected into the soil profile reduced the hydraulic conductivity within the zone of influence. This in turn led to lower ground-water flow rates, allowing for effective interception and treatment of a migrating NAPL plume. Higher air injection rates led to further reductions in hydraulic conductivity, allowing for substantial control of the NAPL plume in the downgradient direction. Overall, this study showed that air sparging can be used to effectively remediate dissolved- and NAPL-phase benzene.     

Synthesis and characterization of nano-hydroxyapatite at ambient temperature using cationic surfactant

Hydroxyapatite (HAP) nanorods were successfully prepared by co-precipitation method using cationic surfactant template, at ambient temperature and pressure. The preparation was done in the customary environment by a process which eliminates the temperature control. The structure of the prepared HAP was confirmed by the FTIR and XRD. HAP rods with diameter ~ 20 nm and length in the range of 100–120 nm were confirmed by FESEM and TEM while the SAED pattern established the crystalline nature of particles. The cytotoxicity studies show IC₅₀ of HAP in 3T3 cell line in the range 850 ± 10 μM for 24 h and 650 ± 10 μM for 48 h treatment.     

Lateral Load Resistance Evaluation of Wood- and Steel-Stud Partition Shear Walls

This paper summarizes the findings of an experimental study to characterize the cyclic racking and monotonic loading performance of wood-stud and steel-stud wall specimens, which were sheathed on both faces with gypsum wall board (GWB). Some specimens were finished with joint compound at the GWB joints and over screw heads. The study provided data on monotonic and cyclic hysteresis load-displacement relationships. Based on the visual inspection of the specimens during the tests, several aspects of the failure modes were noted. Shear-load capacity and drift capacities were determined based on the envelope curves of the hysteresis cycles. A comparison of the envelope curves for steel-stud and wood-stud specimens provided insight as to the relative behaviors of the two wall system types, including capacity, measures of ductility, and energy dissipation. Finally, the study provided better understanding of the effects of finishing GWB joints on the shear capacity of the wall systems.     

Time perspective in socioeconomic inequalities in smoking and body mass index.

Objective: To determine if time perspective plays a mediating role in the relationship between socio-economic position (SEP) and both smoking and body mass index (BMI). Design: 2000 adults aged 18 years and over were randomly selected from the edited electoral register for the city of Newcastle upon Tyne, England and sent a postal questionnaire. Two reminders were sent. Main outcome measures: Socio-economic position was measured using the Index of Multiple Deprivation (IMD) of the area of residence. Time perspective was measured using the Consideration of Future Consequences Scale (CFCS). Smoking and BMI were self-reported. Results: Full data was available for 804 individuals (response rate: 40.2%). After controlling for age, gender and health status, IMD was significantly associated with BMI, smoking status and CFCS score (p