Temperature modelling and prediction for activated sludge systems.

Temperature is an important factor affecting biomass activity, which is critical to maintain efficient biological wastewater treatment, and also physiochemical properties of mixed liquor as dissolved oxygen saturation and settling velocity. Controlling temperature is not normally possible for treatment systems but incorporating factors impacting temperature in the design process, such as aeration system, surface to volume ratio, and tank geometry can reduce the range of temperature extremes and improve the overall process performance. Determining how much these design or up-grade options affect the tank temperature requires a temperature model that can be used with existing design methodologies. This paper presents a new steady state temperature model developed by incorporating the best aspects of previously published models, introducing new functions for selected heat exchange paths and improving the method for predicting the effects of covering aeration tanks. Numerical improvements with embedded reference data provide simpler formulation, faster execution, easier sensitivity analyses, using an ordinary spreadsheet. The paper presents several cases to validate the model.

Perfusion alters free zinc levels in the rodent brain.

BACKGROUND: Fixation of brain tissue is a common practice which allows preservation of tissue and aids in preventing structural and chemical abnormalities. However, fixation procedures may disrupt the levels of biometals such as zinc when compared to tissue that is fresh-frozen. Thus, we sought to determine if any differences in free-zinc levels exist between perfused and fresh-frozen tissue. Zinc is an essential biometal critical for cellular communication and memory and exists in both bound and free forms; the latter playing critical roles in synaptic communication. New method: C57BL/6 J mice were divided into two water types: those given lab water and those given water supplemented with 10 ppm zinc carbonate. Perfusion was carried out with 4% paraformaldehyde on half of the animals in each water group to assess the impact on levels of free Zn as measured through Zinpyr-1 fluorescence. RESULTS: There were significant differences in Zn fluorescence values between Zn-supplemented and lab water groups as well as between perfused and fresh-frozen tissues in the dentate gyrus and CA3 regions of the hippocampus, regions critical in learning & memory. Comparison with existing methods: These results show that when determining a method for euthanasia, any future histological techniques involving assessment of metal content should first be considered. CONCLUSIONS: Researchers must be cautious with the way in which tissue is collected and treated since this can lead to misleading conclusions when linking changes in behavior and relative levels of trace metals.

Oxcarbazepine monotherapy in postherpetic neuralgia unresponsive to carbamazepine and gabapentin.

OBJECTIVES: We present the results of a preliminary, open-label trial to evaluate the efficacy and tolerability of oxcarbazepine in postherpetic neuralgia (PHN) unresponsive to treatment with antiepileptic drugs (carbamazepine and gabapentin) and local anesthetic blocks. MATERIALS AND METHODS: Twenty-four patients were treated with oxcarbazepine monotherapy for 8 weeks. Starting dose was 150 mg/day, subsequently increased by 150 mg/day every 2 days until a maintenance dose of 900 mg/day. Pain was assessed using a visual analog scale (VAS). RESULTS: There was a significant decrease in the mean VAS score following 8 weeks of treatment (Delta=5.33; paired t-test: P <0.0001) compared with baseline. Oxcarbazepine was effective from the first week of treatment. There was a significant reduction in allodynia, leading to improvements in patients' functioning and quality of life. Oxcarbazepine was generally well tolerated. CONCLUSION: Oxcarbazepine appears to be a promising alternative monotherapeutic approach for patients affected by PHN.