NiO/ZnO Composite Derived Metal-Organic Framework as Advanced Electrode Materials for Zinc Hybrid Redox Flow Battery

NiO/ZnO composite derived metal-organic framework (MOF) is used as to modify carbon felt (CF) via a conventional solid-state reaction followed by ultrasonication. The prepared electrode material is used in zinc-hybrid redox flow batteries (RFBs) due to their high redox activity of Zn²⁺/Zn. The electrochemical performance of composite modified CF and pre-treated CF was studied by cyclic voltammetry (CV) in 0.5 M aqueous zinc chloride with 5 M potassium hydroxide solutions showed clear confirmation for enhanced electrocatalytic activity. The unique porous structure of NiO/ZnO-derived MOF with increased surface area improves the battery behavior significantlyThe peak current ratio for the as-prepared material is about 3 times higher than that of the pre-treated CF due to more active sites. Zinc-based RFB with modified CF electrode exhibited better electrochemical performance with voltage efficiency (VE, 88 %), which is higher than true redox flow batteries.     

Toxicity of <Emphasis Type="Italic">Camellia sinensis</Emphasis>-Fabricated Silver Nanoparticles on Invertebrate and Vertebrate Organisms: Morphological Abnormalities and DNA Damages

Our understanding of nanoparticle toxicity and fate in the aquatic environment is still patchy. In the present study, the toxicity of silver nanoparticles coated by Camellia sinensis (Cs) leaf extract metabolites (Cs-AgNPs) was investigated in comparison with C. sinensis leaf extract and AgNO₃ on a micro-crustacean, Ceriodaphnia cornuta, and a fish Poecilia reticulata. 100% mortality of C. cornuta was observed post-exposure to AgNO₃ (40 µg/ml) if compared to the Cs leaf extract and Cs-AgNPs, showing 30 and 56% mortality at the same concentration, respectively. In P. reticulata 100% mortality was observed testing AgNO₃ and Cs-AgNPs post-exposure to 1 and 30 µg/ml, respectively. Light microscopy and CLSM images showed the accumulation of nanoparticles in the intestine of C. cornuta treated with Cs-AgNPs at 40 µg/ml. In addition, histological observations confirmed the abnormal tissue texture in nanoparticle-exposed P. reticulata, if compared to control fishes. Furthermore, C. cornuta and P. reticulata treated with Cs-AgNPs showed DNA damages compared to the control. Overall, these findings indicated relevant limits about the employ of silver-based pesticides in the environment, and also pointed out the Cs-AgNPs were less toxic to C. cornuta and P. reticulata if compared to silver ions.     

A Glycosylated Cationic Block Poly(β-peptide) Reverses Intrinsic Antibiotic Resistance in All ESKAPE Gram-Negative Bacteria

Carbapenem-resistant Gram-negative bacteria (GNB) are heading the list of pathogens for which antibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer-membrane or are excluded by efflux mechanisms. Here, we report a cationic block β-peptide (PAS8-b-PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8-b-PDM12 does not only compromise the integrity of the bacterial outer-membrane, it also deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As a result, PAS8-b-PDM12 sensitizes carbapenem- and colistin-resistant GNB to multiple antibiotics in vitro and in vivo. The β-peptide allows the perfect alternation of cationic versus hydrophobic side chains, representing a significant improvement over previous antimicrobial α-peptides sensitizing agents. Together, our results indicate that it is technically possible for a single adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group, including those resistant to last resort antibiotics.     

Hypolipidemic potential of flowers of Nerium oleander in high fat diet-fed Sprague Dawley rats

Nerium oleander Linn. (NO), an evergreen shrub, is used in folklore medicine as a cardiotonic and exhibits a wide spectrum of bioactivities. Herein, the hypolipidemic potential of the ethanolic extract of flowers of Nerium oleander (ENO) in a minimal dose was assessed. A high fat diet (HFD) resulted in a significant increase in cardiac lipids and lipoproteins and an increase in body weight gain. Simultaneous treatment with ENO significantly lowered the increase in body weight gain, lipid and lipoprotein levels, with a concomitant increase in HDL in the plasma and heart when compared to HFD-fed rats. Likewise, the activities of lipolytic enzymes were also upheld by the ENO treatment in the heart compared to HFD-fed rats. The above findings highlight the possible mechanism of N. oleander as a hypolipidemic agent in its use in folklore medicine as a cardiotonic.     

Production and Characterization of Cellobiohydrolase from a Novel Strain of <Emphasis Type="Italic">Penicillium purpurogenum</Emphasis> KJS506

A high cellobiohydrolase (CBH)-producing strain was isolated and identified as Penicillium purpurogenum KJS506 according to the morphology and comparison of internal transcribed spacer rDNA gene sequence. When rice straw and corn steep powder were used as carbon and nitrogen sources, respectively, a maximum CBH activity of 2.6 U mg-protein⁻¹, one of the highest among CBH-producing microorganisms, was obtained. The optimum temperature and pH for CBH production were 30 °C and 4.0, respectively. The increased production of CBH in P. purpurogenum culture at 30 °C was confirmed by two-dimensional electrophoresis followed by MS/MS sequencing of the partial peptide. The internal amino acid sequences of P. purpurogenum CBH showed a significant homology with hydrolases from glycoside hydrolase family 7. The extracellular CBH was purified to homogeneity by sequential chromatography of P. purpurogenum culture supernatants on a DEAE-sepharose column, a gel filtration column, and then on a Mono Q column with fast-protein liquid chromatography. The purified CBH was a monomeric protein with a molecular weight of 60 kDa and showed broad substrate specificity with maximum activity towards p-nitrophenyl β-d-cellobiopyranoside. P. purpurogenum CBH showed t _1/2 value of 4 h at 60 °C and V _max value of 11.9 μmol min⁻¹ mg-protein⁻¹ for p-nitrophenyl-d-cellobiopyranoside. Although CBHs have been reported, the high specific activity distinguishes P. purpurogenum CBH.     

Spectrofluorometric studies on the binding interaction of bioactive imidazole with bovine serum albumin: a DFT based ESIPT process

Bioactive imidazole derivatives were synthesized and characterized by NMR spectra, mass and CHN analysis. An excited state intramolecular proton transfer (ESIPT) process in hydroxy imidazole has been studied using emission spectroscopy. In hydrocarbon solvent, the tautomer emission predominates over the normal emission and in alcoholic solvent like ethanol; a dramatic enhancement of normal emission is observed which was due to increased solvation. DFT calculation on energy, charge distribution of the rotamers in the ground and excited states of the imidazole derivative were performed and discussed. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than in the ground state. The interaction between bioactive imidazole derivative and bovine serum albumin (BSA) was investigated.     

Solvatochromic analysis of some N-nitroso oxime derivatives--Taft and Catalan approach

Some novel N-nitroso oxime derivatives were synthesized and characterized by (1)H, (13)C, (1)H-(1)H and (1)H-(13)C COSY NMR spectra. The spectra of all these N-nitroso oximes reveal the presence of two isomers labelled as E (-NOH group is anti to N-N=O moiety) and Z (-NOH group is syn to N-N=O moiety) in solution and the coupling constants ruled out the possibility of normal chair conformation. From the theoretical studies and coupling constant values it was found that both E (major) and Z (minor) isomers of N-nitroso oximes exist as an equilibrium mixture of CA and boat conformation (B(1)) and this was also supported by DFT calculation. The photophysical properties of these oxime derivatives were studied and the observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed due to the presence of non-chair conformation of N-nitroso oxime derivatives.     

Luminescent study on the binding interaction of bioactive imidazole with bovine serum albumin-A static quenching mechanism

Novel bioactive imidazole derivatives were synthesized and characterized by NMR spectra, mass and CHN analysis. The interaction between the imidazole derivative and bovine serum albumin (BSA) was investigated by fluorescence and UV-vis absorption spectroscopy. The fluorescence quenching of BSA by the imidazole derivatives may be due to the formation of imidazole-BSA complex. The fluorescence quenching mechanism of BSA by imidazole was analyzed and the binding constant has been calculated. The binding distance between imidazole and BSA was obtained based on Forester's non-radiation energy transfer (FRET). The effect of some common ions on the binding constant between imidazole and BSA was also examined.     

Comparison of Bacterial Communities in the Throat Swabs from Healthy Subjects and Pharyngitis Patients by Terminal Restriction Fragment Length Polymorphism

Terminal restriction fragment length polymorphism (T-RFLP) analysis was applied to characterize bacterial flora present in the throats of healthy subjects and pharyngitis patients. The 16S?rRNA genes of bacteria present in throat metagenome were amplified by PCR with 6-carboxy-fluorescein (6-FAM)-labeled universal forward primer (27?F) and a universal reverse primer (1513R). The 16S rDNAs were digested with restriction enzymes with 4-bp recognition sites (MspI or RsaI) and analyzed by using an automated DNA sequencer. T-RFLP patterns were numerically analyzed using computer programs. From analysis of the throat bacterial community, patterns derived from MspI and RsaI digested samples of healthy subjects and pharyngitis patients were grouped into different clusters, though RsaI digested samples showed some uncertainty. Pharyngitis throats generated an average species richness of 9 [±2.1 (SD)] and 10 (±2.9) for MspI and RsaI digests, respectively, whereas healthy throats generated 6.3 (±1.2) and 6.1 (±1.5) in MspI and RsaI digests, respectively. These results suggest that samples from pharyngitis patients contain an unexpected diversity of causative bacteria. The pharyngitis throats were colonized with a rich diversity of bacterial species than that of healthy throats. Using T-RFLP, we are able to detect a model bacterium, Streptococcus pyogenes SF370, and T-RF patterns were consistent with the Streptococcal T-RFLP patterns. Our study indicates that T-RFLP analysis is useful for the assessment of diversity of throat bacterial flora and rapid comparison of the community structure between subjects with and without pharyngitis.     

Photophysical Properties of Novel Picrate Derivatives – Solvent Effect

H and ¹³C NMR spectra were recorded for some novel picrate derivatives derived from 3,3-dimethyl-2,6-diarylpiperidin-4-ones and 3-benzyl-2,6-diarylpiperidin-4-one. The photophysical properties of the picrate derivatives were studied in several solvents, which include a wide range of apolar, polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed due to the presence of increased electrostatic interaction between N-protonated piperidone ring and picryl anion ring so that the picryl anion ring lies perpendicular to the plane of the N-protonated piperidone ring i.e., non co-planarity. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions. The higher fluorescence quantum yield of the picrate derivatives are observed in polar media.