Optimization and activation of renewable durian husk for biosorption of lead (II) from a aqueous medium

Background: Biosorption of lead Pb(II) by durian husk activated carbon (DHAC) was investigated. The main aim of this work is to explore the effect of operating variables such as pH, biosorbent dose, temperature, initial metal ion concentration and contact time on the removal of Pb(II) from synthesized aqueous medium using a response surface methodology (RSM) technique. The experimentation was performed in two sets, namely set 1 and set 2. Results: For experimental set 1, pH was set to 7.0. The optimum conditions for the remaining parameters were determined to be 0.39 g DHAC dose, 60 min contact time and 100 mg L−1 of initial metal ion concentration, which yielded maximum biosorption capacity of 14.6 mg g−1. For experimental set 2, 41.27 °C, 8.95 and 99.96 mg L−1 were the optimum conditions determined for temperature, pH and initial Pb(II) concentration, respectively; which revealed a maximum adsorption capacity of 9.67 mg g−1. Characterization of the adsorbent revealed active functional groups such as hydroxyl, carboxylic, alcohol and hemicellulose. The equilibrium adsorption data obeyed the Langmuir isotherm and pseudo‐second‐order kinetic models with maximum Langmuir uptake of 36.1 mg g−1. Conclusions: The biosorbent was capable of reuse, so that the abundant durian husk could be utilized effectively for the removal of Pb(II) from polluted water

Autonomic cerebral vascular response to sildenafil in diabetic patient

<p>Abstract</p> <p>Background</p> <p>Erectile dysfunction is a common problem in type 2 diabetic patients who are at higher risk of cerebrovascular events, and it's recorded with sildenafil, a drug which is primarily used for erectile dysfunction.</p> <p>Objectives</p> <p>We tested the hypothesis whether or not sildenafil modulates cerebrovascular reactivity (CVR) in patients with type 2 diabetes mellitus.</p> <p>Methods</p> <p>A total of 35 male participants were enrolled; eighteen with type 2 diabetes mellitus matched with seventeen normal individuals. Transcranial Doppler Ultrasonographic examination (TCD) was performed for all participants to insonate the middle cerebral artery (MCA) through a trans-temporal window. CVR was assessed by using breath holding (BH)-hyperventilation (HV) test, before and after oral 50 mg sildenafil; recordings were analyzed by using SPSS program version 12.</p> <p>Results</p> <p>In normal individuals, sildenafil did not result in statistically significant change in breath holding index (BHI) from 0.91 ± 0.11 to 0.81 ± 0.09 and full range of vasodilatation (FVD) from (59.4% ± 6.3%) to (53.7% ± 4.9%). In diabetic patients, giving sildenafil resulted in significant increase in BHI (from 0.74 ± 0.14 to 1.03 ± 0.14) and FVD (from 60.2% ± 4.96% to 74% ± 4.8%), (p < 0.05).</p> <p>Conclusion</p> <p>Sildenafil significantly improves CVR in type 2 diabetic patients but not in normal subjects.</p