Mass transfer of hazardous organic compounds in soil matrices relevant to thermal desorption/incineration

Soils contaminated with hazardous organic compounds have been known to threaten human health both directly through various contact mechanisms and indirectly through leaching or transfer to the food chain. Thermal desorption of contaminated soil matrices with secondary treatment of the effluent gases (collection, incineration, etc) is one of most feasible and developing technologies for cleaning of contaminated soils. There is, however, little known about the mass transfer principles of organic contaminants through the heated soil matrices. The objectives of this study is, therefore, to learn and understand details of the mass transfer processes of organic compounds in these soil matrices. We have performed several varied types of experiments to determine specific mass transfer parameters and developed a model which accurately describes the process and can be utilized to obtain optimal operation conditions. Chromatographic response analysis and transient adsorption desorption equations of flow through soil columns have been utilized in developing the initial model. We incorporate intra (pore) and interparticle diffusion, equilibria, in addition to normal mass transfer parameters of axial dispersion and film mass transfer around particle surface.Experiments primarily consist of plug flow deposition of the contaminants on a well characterized soil column and saturation desorption of a soil bed, in addition to equilibrium tests. The plug flow deposition experiments connected with chromatographic analysis successfully yielded equilibrium constants, heats of adsorption and mass transfer parameters. In addition we identified a minimum allowable temperature (MAT), below which the organic compounds are not completely desorbed from the soil within a 1 hour operating time. Resulting equilibrium constants were strongly dependent on temperature and were revealed to follow the van\u27t Hoff equation above the MAT\u27s. Analysis of heats of adsorption showed that the organic - soil system can be considered as a moderately weak physical adsorption system. Analysis results utilizing an experimental equilibrium test apparatus demonstrated that adsorption isotherms show good linearity at lower concentration and that linear zone tends to extend to higher concentrations with increasing temperature. The slopes of linear adsorption isotherms tend to decrease with increasing temperature, indicating less adsorption. As a result of desorption experiments using the equilibrium apparatus, data showed hysteresis phenomena at lower temperatures probably due to irreversibility of adsorption processes. The observed hysteresis tended to become weaker i.e. the data for desorption closely followed the adsorption isotherm as temperature increases. An analytical solution and a numerical approach using orthogonal collocation have been utilized for the purpose of predicting the transient mass transfer behavior of organics in a soil column. The two methods result in satisfactory coincidence

Cupping for Treating Pain: A Systematic Review

The objective of this study was to assess the evidence for or against the effectiveness of cupping as a treatment option for pain. Fourteen databases were searched. Randomized clinical trials (RCTs) testing cupping in patients with pain of any origin were considered. Trials using cupping with or without drawing blood were included, while trials comparing cupping with other treatments of unproven efficacy were excluded. Trials with cupping as concomitant treatment together with other treatments of unproven efficacy were excluded. Trials were also excluded if pain was not a central symptom of the condition. The selection of studies, data extraction and validation were performed independently by three reviewers. Seven RCTs met all the inclusion criteria. Two RCTs suggested significant pain reduction for cupping in low back pain compared with usual care (P < .01) and analgesia (P < .001). Another two RCTs also showed positive effects of cupping in cancer pain (P < .05) and trigeminal neuralgia (P < .01) compared with anticancer drugs and analgesics, respectively. Two RCTs reported favorable effects of cupping on pain in brachialgia compared with usual care (P = .03) or heat pad (P < .001). The other RCT failed to show superior effects of cupping on pain in herpes zoster compared with anti-viral medication (P = .065). Currently there are few RCTs testing the effectiveness of cupping in the management of pain. Most of the existing trials are of poor quality. Therefore, more rigorous studies are required before the effectiveness of cupping for the treatment of pain can be determined