Adsorption behavior of benzenesulfonic acid by novel weakly basic anion exchange resins

Two novel weakly basic anion exchange resins(SZ-1 and SZ-2) were prepared via the reaction of macroporous chloromethylated polystyrene-divinylbenzene(Cl-PS-DVB) beads with dicyclohexylamine and piperidine, respectively. The physicochemical structures of the resulting resins were characterized using Fourier Transform Infrared Spectroscopy and pore size distribution analysis. The adsorption behavior of SZ-1 and SZ-2 for benzenesulfonic acid(BA) was evaluated, and the common commercial weakly basic anion exchanger D301 was also employed for comparison purpose. Adsorption isotherms and influence of solution p H, temperature and coexisting competitive inorganic salts(Na2SO4and Na Cl) on adsorption behavior were investigated and the optimum desorption agent was obtained.Adsorption isotherms of BA were found to be well represented by the Langmuir model.Thermodynamic parameters involving ΔH, ΔG and ΔS were also calculated and the results indicate that adsorption is an exothermic and spontaneous process. Enhanced selectivity of BA sorption over sulfate on the two novel resins was observed by comparison with the commercial anion exchanger D301. The fact that the tested resins loaded with BA can be efficiently regenerated by Na Cl solution indicates the reversible sorption process. From a mechanistic viewpoint, this observation clearly suggests that electrostatic interaction is the predominant adsorption mechanism. Furthermore, results of column tests show that SZ-1possesses a better adsorption property than D301, which reinforces the feasibility of SZ-1for potential industrial application.     

Perturbations in the antioxidant metabolism during Newcastle disease virus (NDV) infection in chicken

The aim of the present study was to investigate the effect of vitamin E on pro/anti-oxidant status in the liver, brain and heart of Newcastle disease virus (NDV) infected chickens. Activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and the levels of reduced glutathione and malonaldehyde were estimated in selected tissues of uninfected, NDV-infected and NDV + vit. E-treated chickens. A significant increase in MDA levels in brain and liver (p < 0.05) was observed in NDV-infected chickens when compared to controls. The activities of SOD, CAT, GPx, GR, GST and levels of GSH were significantly (p < 0.05) decreased in brain and liver of NDV-infected chickens over controls. On the other hand, a significant decreased MDA levels and enhanced antioxidant enzyme activity levels were observed in NDV + vit. E-treated animals compared to NDV-infected chickens. Histopathological studies revealed that liver of NDV infected chicken shows focal coagulation and infiltration of hepatocytes, whereas neuronal necrosis and degeneration of Purkinje cells were observed in brain and moderate infiltration of inflammatory cells was observed in heart. However such histological alterations were not observed in NDV + vit. E-treated animals. The results of the present study, thus demonstrated that antioxidant defense mechanism is impaired after the induction of NDV, suggesting its critical role in cellular injury in brain and liver. Further, the results also suggest that vitamin E treatment will ameliorate the antioxidant status in the infected animals. The findings could be beneficial to understand the role of oxidative stress in the pathogenesis of NDV and therapeutic interventions of antioxidants.     

A comparative assessment of land management approaches in Bhutan

Arable land in Bhutan is under serious threats of land degradation. Proper land management approach is needed to control soil erosion problems. This study is an attempt to characterize and document the conventional and the community-based land management approaches, applied in Chukha and Dagana districts, respectively. The study tried to make a comparative assessment of their social, economic and environmental impacts on the participating farmers. Farmers’ level of participation in the program, implementation of the soil erosion control measures (SECM) and subsequent social, economic and environmental impacts were found to be significantly influenced by the type of approach applied. The study found that community-based approach is by any means better suited for the study sites than the conventional approach. The social, economic and environmental attributes of respondents from the community-based approach were found to have improved significantly as compared to the conventional approach. The community-based approach was thus found to have a higher potential to meet the diverse requirements of rural subsistence farming communities in Bhutan than the conventional approach.