Ex situ bioremediation of pyrene contaminated soil in bio-slurry phase reactor operated in periodic discontinuous batch mode: Influence of bioaugmentation

Ex situ treatment of simulated pyrene-contaminated soil was studied in bio-slurry phase reactors operated in periodic discontinuous batch mode under anoxic–aerobic–anoxic–anoxic microenvironment. Experiments were performed in six different bio-slurry phase reactors (retention time of 120 h; soil loading rate of 20 kg soil/m³-day; operating temperature at 28±2 °C) by varying substrate concentration (substrate loading rate (SLR), 0.12, 0.24 and 0.36 g pyrene/kg soil-day) and bioaugmentation application (domestic sewage inoculum; CFU—2×10⁶). The performance of slurry phase reactors was found to be dependent on the applied SLR and application of bioaugmentation (domestic sewage as augmented inoculum). Control reactor (killed control) showed only 6% of pyrene degradation while the non-augmented reactor showed an efficiency of 34% (substrate degradation rate (SDR)—0.0165 g pyrene/kg soil-day). In the case of augmented reactors, the system operated with low SLR showed a pyrene degradation efficiency of almost 90% (SDR—0.04 g pyrene/kg soil-day) and the reactor with high SLR showed 50% (SDR—0.025 g pyrene/kg soil-day) of pyrene degradation indicating the dependence of performance on the substrate concentration. Colony forming units (CFUs) variation was in good agreement with the performance of the reactors with respect to pyrene degradation. On the whole, pyrene degradation rate was greater in the augmented reactors compared to non-augmented reactors.     

Effect of novel N-aryl sulfonamide substituted 3-morpholino arecoline derivatives as muscarinic receptor 1 agonists in Alzheimer's dementia models

A series of novel, potent, and selective muscarinic receptor 1 agonists (M1 receptor agonists) that employ a key N-substituted morpholine Arecoline moiety has been synthesized as part of research effort for the therapy of Alzheimer’s diseases. The ester group of arecoline (which is reported as muscarinic agonist) has been replaced by N-substituted morpholine ring. The structure–activity relationship reveals that the electron donating 4-substituted sulfonyl derivatives (9a, 9b, 9c, and 9e) on the nitrogen atom of the morpholine ring increases the affinity of M1 receptor binding 50- to 80-fold greater than the corresponding arecoline. Other derivatives also showed considerable M1 receptor binding affinity.     

Elucidating the interactions and phytotoxicity of zinc oxide nanoparticles with agriculturally beneficial bacteria and selected crop plants

There is a growing interest in the use of bioinoculants to assist mineral fertilizers in improving crop production and yield. Azotobacter and Pseudomonas are two agriculturally relevant strains of bacteria which have been established as efficient bioinoculants. An experiment involving addition of graded concentrations of zinc oxide (ZnO) nanoparticles was undertaken using log phase cultures of Azotobacter and Pseudomonas. Growth kinetics revealed a clear trend of gradual decrease with Pseudomonas; however, Azotobacter exhibited a twofold enhancement in growth with increase in the concentration of ZnO concentration. Scanning electron microscopy (SEM), supported by energy-dispersive X-ray (EDX) analyses, illustrated the significant effect of ZnO nanoparticles on Azotobacter by the enhancement in the abundance of globular biofilm-like structures and the intracellular presence of ZnO, with the increase in its concentration. It can be surmised that extracellular mucilage production in Azotobacter may be providing a barrier to the nanoparticles. Further experiments with Azotobacter by inoculation of wheat and tomato seeds with ZnO nanoparticles alone or bacteria grown on ZnO-infused growth medium revealed interesting results. Vigour index of wheat seeds reduced by 40–50% in the presence of different concentrations of ZnO nanoparticles alone, which was alleviated by 15–20%, when ZnO and Azotobacter were present together. However, a drastic 50–60% decrease in vigour indices of tomato seeds was recorded, irrespective of Azotobacter inoculation.     

Characterisation,screening and selection of Bacillus subtilis isolates for its biocontrol efficiency against major rice diseases

A Soil bacterium, Bacillus subtilis, isolated from the rhizosphere of rice, showed high biocontrol activity against blast, sheath blight and bacterial blight. In the present study, four B. subtilis strains isolated from paddy soil were studied under laboratory, greenhouse and field conditions. Among the four strains assayed, UASP17 gave maximum inhibition of paddy pathogens and was validated under field trials. B. subtilis (UASP17) under different doses and methods of applications was evaluated for two seasons at Agriculture Research Station (UAS, Raichur). UASP17 was effective in reducing the severity of blast (9.00% and 15.57%), bacterial leaf blight (BLB) (5.00% and 6.11%) and sheath blight (11.93% and 4.17%) diseases for two seasons. The application of bioagent also increased the paddy grain yield (61.00 and 64.30?Q/ha) in the two seasons, respectively. Taken together, these results indicate that B. subtilis UASP17 as seedling dip for 30?min (10?mL/L of water) prior to transplanting and 2.50?L/ha foliar application was effective in managing the diseases of paddy.     

Extraction of Y2O3:Cr3+ nanophosphor by eco‐friendly approach and its suitability for white light‐emitting diode applications

Cr³⁺‐doped Y₂O₃ (0.5–9 mol%) was synthesized by a simple solution combustion method using Aloe vera gel as a fuel/surfactant. The final obtained product was calcined at 750°C for 3 h, which is the lowest temperature reported so far for the synthesis of this compound. The calcined product was confirmed for its crystallinity and purity by powder X‐ray diffraction (PXRD) studies which showed a single‐phase nano cubic phosphor. The particles size estimated by Scherrer formula was in the range of 6–19 nm. The UV–vis spectra showed absorption bands at 198, 272 and 372 nm having band gap energy in the range 4.00–4.26 eV. In order to investigate the possibility of its use in white light emitting display applications, the photoluminescence properties of Cr³⁺‐doped Y₂O₃ nanophosphors were studied at an excitation wavelength in the near ultraviolet (UV) light region (361 nm). The emission spectra consisted of emission peaks in the blue (⁴F_9/2 → ⁶H_15/2), orange (⁴F_9/2 → ⁶H_13/2) and red (⁴F_9/2 → ⁶H_11/2) regions. The CIE coordinates (0.33, 0.33) lie in the white light region. Hence Y₂O₃:Cr³⁺ can be used for white light‐emitting diode (LED) applications.     

Open‐Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge‐Transfer Bands

In organic solar cells (OSCs), the energy of the charge‐transfer (CT) complexes at the donor–acceptor interface, E _CT, determines the maximum open‐circuit voltage (V _OC). The coexistence of phases with different degrees of order in the donor or the acceptor, as in blends of semi‐crystalline donors and fullerenes in bulk heterojunction layers, influences the distribution of CT states and the V _OC enormously. Yet, the question of how structural heterogeneities alter CT states and the V _OC is seldom addressed systematically. In this work, we combine experimental measurements of vacuum‐deposited rubrene/C₆₀ bilayer OSCs, with varying microstructure and texture, with density functional theory calculations to determine how relative molecular orientations and extents of structural order influence E _CT and V _OC. We find that varying the microstructure of rubrene gives rise to CT bands with varying energies. The CT band that originates from crystalline rubrene lies up to ≈0.4 eV lower in energy compared to the one that arises from amorphous rubrene. These low‐lying CT states contribute strongly to V _OC losses and result mainly from hole delocalization in aggregated rubrene. This work points to the importance of realizing interfacial structural control that prevents the formation of low E _CT configurations and maximizes V _OC.     

Modulation of carbonic anhydrase activity in two nitrogen fixing cyanobacteria, Nostoc calcicola and Anabaena sp

The activity of enzyme carbonic anhydrase (CA) was investigated in two diazotrophic cyanobacteria, Anabaena sp. (ARM 629) and Nostoc calcicola, in the presence of CO2/NaHCO3 and different inhibitors. The CA activity increased when the cells were pretreated with a high concentration of CO2/NaHCO3 and then transferred to ambient level CO2. Maximum activity of CA was observed after 8 h of incubation in light on transfer of cells from high Ci to ambient level CO2, and was low when incubated in dark. Addition of the photosynthetic inhibitor DCMU brought about a differential reduction in CA activity, depending on the carbon source (NaHCO3/CO2). CA inhibitors--ethoxyzolamide (EZ) and acetazolamide (AZ)--inhibited the enzyme activity in both the genera, but the extent of inhibition was greater in Anabaena sp. than in N. calcicola. Such a variation in extent of inhibition/stimulation of CA activity being different in the two genera reflects differences in their inherent potential and genetic background. The relevance of such cyanobacterial strains as CO2 sinks is also discussed.