[Effects of nitrogen fertilizer reduction and biochar application on paddy soil nutrient and nitrogen uptake of rice]. / å‡æ°®é æ–½ç¨»ç§†ç”Ÿç‰©ç‚­å¯¹ç¨»ç”°åœŸå£¤å »åˆ†åŠæ¤æ ªæ°®ç´ å¸æ”¶çš„å½±å“.

We explored the impacts of nitrogen (N) reduction and biochar application on soil fertility and nutrient uptake of rice in early and late seasons of 2018 with a field experiment. There were six treatments, including control (no N application, CK), conventional N application (N100), 20% N reduction (N80), 20% N reduction plus biochar application (N80+BC), 40% N reduction (N60), 40% N reduction plus biochar application (N60+BC). Our results showed that 20% and 40% N reduction and/or with biochar application did not affect soil pH, organic matter, total N, total phosphorous (P), total potassium (K), ammonium N, available P and K in comparison with N100 treatment. N80+BC and N60+BC substantially increased soil cation exchange capacity (CEC) at tillering stage and electrical conductivity (EC) at heading stage in late season, respectively. Compared with the treatment with single N reduction, N80+BC significantly increased soil available K in early and late seasons and soil pH and total N in late season, while N60+BC increased soil total K at mature stage in early season. Soil nitrate content was decreased along with the growth stages for all treatments in early season. Compared with tillering stage, soil nitrate N content in conventional N application at heading stage and mature stage was decreased by 50.0% and 71.6%, respectively. Soil nitrate content in biochar treatment only was decreased by 6.3%-45.5%. N application along with biochar application had no significant effects on plant N uptake and utilization in early season. However, N reduction with biochar application significantly increased plant N uptake and N utilization rate by 34.8%-52.4% in late season, compared to conventional N application and single N reduction. Our findings suggest that adequate N reduction along with biochar application could maintain soil health and improve plant N uptake and utilization efficiency.

Combination of pharmacophore hypothesis and molecular docking to identify novel inhibitors of HCV NS5B polymerase.

Hepatitis C virus (HCV) infection or HCV-related liver diseases are now shown to cause more than 350,000 deaths every year. Adaptability of HCV genome to vary its composition and the existence of multiple strains makes it more difficult to combat the emergence of drug-resistant HCV infections. Among the HCV polyprotein which has both the structural and non-structural regions, the non-structural protein NS5B RNA-dependent RNA polymerase (RdRP) mainly mediates the catalytic role of RNA replication in conjunction with its viral protein machinery as well as host chaperone proteins. Lack of such RNA-dependent RNA polymerase enzyme in host had made it an attractive and hotly pursued target for drug discovery efforts. Recent drug discovery efforts targeting HCV RdRP have seen success with FDA approval for sofosbuvir as a direct-acting antiviral against HCV infection. However, variations in drug-binding sites induce drug resistance, and therefore targeting allosteric sites could delay the emergence of drug resistance. In this study, we focussed on allosteric thumb site II of the non-structural protein NS5B RNA-dependent RNA polymerase and developed a five-feature pharmacophore hypothesis/model which estimated the experimental activity with a strong correlation of 0.971 & 0.944 for training and test sets, respectively. Further, the Güner-Henry score of 0.6 suggests that the model was able to discern the active and inactive compounds and enrich the true positives during a database search. In this study, database search and molecular docking results supported by experimental HCV viral replication inhibition assays suggested ligands with best fitness to the pharmacophore model dock to the key residues involved in thumbs site II, which inhibited the HCV 1b viral replication in sub-micro-molar range.