Biocomputational Assessment of Natural Compounds as a Potent Inhibitor to Quorum Sensors in Ralstonia solanacearum

Ralstonia solanacearum is among the most damaging bacterial phytopathogens with a wide number of hosts and a broad geographic distribution worldwide. The pathway of phenotype conversion (Phc) is operated by quorum-sensing signals and modulated through the (R)-methyl 3-hydroxypalmitate (3-OH PAME) in R. solanacearum. However, the molecular structures of the Phc pathway components are not yet established, and the structural consequences of 3-OH PAME on quorum sensing are not well studied. In this study, 3D structures of quorum-sensing proteins of the Phc pathway (PhcA and PhcR) were computationally modeled, followed by the virtual screening of the natural compounds library against the predicted active site residues of PhcA and PhcR proteins that could be employed in limiting signaling through 3-OH PAME. Two of the best scoring common ligands ZINC000014762512 and ZINC000011865192 for PhcA and PhcR were further analyzed utilizing orbital energies such as HOMO and LUMO, followed by molecular dynamics simulations of the complexes for 100 ns to determine the ligands binding stability. The findings indicate that ZINC000014762512 and ZINC000011865192 may be capable of inhibiting both PhcA and PhcR. We believe that, after further validation, these compounds may have the potential to disrupt bacterial quorum sensing and thus control this devastating phytopathogenic bacterial pathogen.     

Crystallization induced room-temperature phosphorescence and chiral photoluminescence properties of phosphoramides

We report the design and synthesis of a series of room temperature phosphorescent phosphoramides TPTZPO, TPTZPS, and TPTZPSe with a donor (phenothiazine)–acceptor (P = X, X = O, S, and Se) architecture. All the compounds show structureless fluorescence with a nanosecond lifetime in dilute solutions. However, these compounds show dual fluorescence and room temperature phosphorescence (RTP) in the solid state. Both the intensity and energy of luminescence depend on the heteroatom attached to the phosphorus center. For example, compound TPTZPO with the P O unit exhibits fluorescence at a higher energy region than TPTZPS and TPTZPSe with the P S and P Se groups, respectively. Crystalline samples of TPTZPO, TPTZPS, and TPTZPSe show stronger RTP than the amorphous powder of respective compounds. Detailed steady-state, time-resolved photoluminescence and computational studies established that the ³n–π* state dominated by the phenothiazine moiety is the emissive state of these compounds. Although TPTZPS and TPTZPSe crystallized in the chiral space group, only TPTZPSe showed chiroptical properties in the solid state. The luminescence dissymmetry factor (g_lum) value of TPTZPS is small and below the detection limit, and a CPL spectrum could not be observed for this compound.

The crystallization-induced room temperature phosphorescence and CPL of phosphoramides are reported. The nonplanar phenothiazine and the tetrahedral geometry of phosphorus curbed the non-radiative deactivation pathways, which led to improved RTP.     

A facile green synthesis of silver nanoparticles: An investigation on catalytic hydroxylation studies for efficient conversion of aryl boronic acids to phenol

Ag nanoparticles (AgNPs) catalyst material is bio-synthesized and fully examined using various spectroscopy and microscopy techniques. Further this synthesized material is used for hydroxylation reaction, for this purpose we developed a simple and versatile bio-based method from aryl boronic acids to phenol. The reaction was studied in the presence of low cost ligand in a hydrated reaction medium without any hazardous organic solvents, as a result a finite amount of yield was achieved in short time (<15 min). The hydroxylation reaction is further carried out in a series of different arenes substituted samples with good amount of yields.     

Theoretical Investigation of the Lead-Free K2InBiX6 (X = Cl,Br) Double Perovskite Compounds Using Ab Initio Calculation

JETP Letters - In this study, we employ the full potential linearized augmented plane wave technique based on density functional theory applied in the WIEN2k code to examine the structural,...     

CuMoO4 Bimetallic Nanoparticles,An Efficient Catalyst for Room Temperature C−S Cross-Coupling of Thiols and Haloarenes

Cu^II catalyst is less efficient at room temperature for C−S cross-coupling. C−S cross-coupling by Cu^II catalyst at room temperature is not reported; however, doping of copper with molybdenum metal has been realized here to be more efficient for C−S cross-coupling in comparison to general Cu^II catalyst. The doped catalyst CuMoO₄ nanoparticle is found to be more efficient than copper. The catalyst works under mild conditions without any ligand at room temperature and is recyclable and effective for a wide range of thiols and haloarenes (ArI, ArBr, ArF) from milligram to gram scale. The copper-based bimetallic catalyst is developed and recognized for C−S cross-coupling of haloarenes with alkyl and aryl thiols.     

Rapid Discrimination of Bacterial Drug Resistivity by Array-Based Cross-Validation Using 2D MoS2

The precise discrimination of microbes based on family, class and drug resistivity is essential for the early diagnosis of infectious diseases. Information about the type and strength of drug resistivity can help the analyst to prescribe a suitable antibiotic at the proper dosage to completely eradicate microbes without giving them a chance to gain further resistance. Herein, we propose a sensor array based on the use of cationic two-dimensional MoS₂ units and green fluorescence protein as building blocks. Cationic surfaces of receptors with various functionality were suitable for tunable interaction with anionic surfaces of microbes. The array successfully discriminates six different bacterial strains. The versatile ability of the receptors to bind with the wild-type as well as the corresponding ampicillin-resistant strain contributed significantly to rapid detection with high sensitivity. The optimized array was able to classify five different types and three different extents of drug-resistant variants of Escherichia coli by using bacteria cells and lysates. Finally, we have introduced the cross identification method using both bacteria cells and lysates and we found a great enhancement of detection in sensitivity and accuracy. This is the first report of this approach, which can be extended to many other methods for better accuracy in array-based detection.     

Ionic liquid-induced unprecedented size enhancement of aggregates within aqueous sodium dodecylbenzene sulfonate

Physicochemical properties of aqueous micellar solutions may change in the presence of ionic liquids (ILs). Micelles help to increase the aqueous solubility of ILs. The average size of the micellar aggregates within aqueous sodium dodecylbenzene sulfonate (SDBS) is observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) to increase in a sudden and drastic fashion as the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) is added. Similar addition of [bmim][PF(6)] to aqueous sodium dodecyl sulfate (SDS) results in only a slow gradual increase in average aggregate size. While addition of the IL [bmim][BF(4)] also gives rise to sudden aggregate size enhancement within aqueous SDBS, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF(4)]), and inorganic salts NaPF(6) and NaBF(4), only gradually increase the assembly size upon their addition. Bulk dynamic viscosity, microviscosity, dipolarity (indicated by the fluorescent reporter pyrene), zeta potential, and electrical conductance measurements were taken to gain insight into this unusual size enhancement. It is proposed that bmim(+) cations of the IL undergo Coulombic attractive interactions with anionic headgroups at the micellar surface at all [bmim][PF(6)] concentrations in aqueous SDS; in aqueous SDBS, beyond a critical IL concentration, bmim(+) becomes involved in cation-π interaction with the phenyl moiety of SDBS within micellar aggregates with the butyl group aligned along the alkyl chain of the surfactant. This relocation of bmim(+) results in an unprecedented size increase in micellar aggregates. Aromaticity of the IL cation alongside the presence of sufficiently aliphatic (butyl or longer) alkyl chains on the IL appear to be essential for this dramatic critical expansion in self-assembly dimensions within aqueous SDBS.     

Fluctuation induced magneto-conductivity studies in YBa2Cu3O7−δ + xBaZrO3 composite high-Tc superconductors

Fluctuations on the electrical conductivity of polycrystalline YBa₂Cu₃O_7?δ + xBaZrO₃ (x = 1.0, 2.5, 5.0 and 10.0 wt.%) superconductors were investigated from the resistivity vs. temperature data for zero field and 8 T (Tesla) external magnetic fields. Attempts have been made to identify the optimum inclusion of BaZrO₃ (BZO) in YBa₂Cu₃O_7?δ (YBCO) superconductors. The phase formation, texture and grain alignments were analyzed by XRD and SEM techniques. Then the effects of superconducting fluctuations on the electrical conductivity of granular composite superconductors were studied for zero field and 8 T external magnetic fields. Though inclusions of BZO sub-micron particles are not expected to influence superconducting order-parameter fluctuation (SCOPF) much, the transition from 2D to 3D of the order parameter in the mean-field region depends on the BZO content in the composites. It has been observed that BZO residing at the grain boundary of YBCO matrix influences the tailing region without having significant change in the mean-field critical temperature. In the present work, attention has been focused mostly in the experimental domain relatively above the T_c. It reveals that, 1 wt.% composite exhibits a better superconducting property in comparison with pure YBCO.