Surface cationization of cellulose to enhance durable antibacterial finish in phytosynthesized silver nanoparticle treated cotton fabric

Cellulose - Elimination of disease-causing bacteria from cotton fabrics is critically important to control several bacteria-mediated infections in humans. Antibacterial nanoparticles, particularly...     

Synthesis,Phase Transition of La<Subscript>0.69</Subscript>Sr<Subscript>0.31</Subscript>MnO<Subscript>3</Subscript> Nanoperovskites Toward Its Versatile Structural,Electrical and Mechanical Properties Employing Ultrasonic Measurements

The present investigation correlates the propagation of ultrasonic waves with various micro structural features of nano La_0.69Sr_0.31MnO₃ (LSMO) perovskites with different grain sizes. A solid state reaction followed by the ball milling technique was used to synthesize the nano LSMO perovskite samples with various grain sizes. The occurrence of ferro-paramagnetic transition temperature (T_c) was explored through the observed anomalous behaviour in ultrasonic velocities, attenuations and elastic moduli. As the particle size gets reduced, lower T_c and broader transitions are observed due to the distribution of grain boundaries. The diffusion of the FM–PM phase transition along with decrease in T_c is correlated due to the effect of particle size. Furthermore structural, vibrational and electrical properties of nanosized LSMO perovskite samples with different grain sizes were studied by XRD, FTIR, BET surface area measurement, HRSEM, TEM and four probe conductivity studies. The phase of the synthesized nano LSMO perovskite samples are perfectly indexed to pure rhombohedral perovskite type crystal structure. The conductivity study proves the semiconductor nature of the nano LSMO perovskite samples. In addition to this, the peak broadening in ultrasonic studies at phase transition is in line with the observation made from the XRD pattern for the prepared nano LSMO perovskite samples.     

Synthesis, stereochemistry, and antimicrobial activity of 2,6-diaryl-3-(arylthio)piperidin-4-ones

A series of novel 2,6-diaryl-3-(arylthio)piperidin-4-ones have been synthesized by reaction of arylthioacetones, substituted aromatic aldehydes, and methylamine/ammonium acetate and their structures elucidated by (1)H, (13)C, and 2D NMR (H, H-COSY, C, H-COSY, HMBC, and NOESY) spectroscopy. The NMR data reveal that all these piperidones exist in chair conformation with the 2,6-diaryl groups equatorially oriented, while the arylthio group prefers to be in either an equatorial or axial orientation depending on whether the substituent in the 2,6-diaryl rings is present in 4- or 2-position, respectively. In the case of NH-2,6-diaryl-3-(arylthio)piperidin-4-ones with o-substituted 2,6-diaryl groups, the arylthio group prefers the axial orientation presumably in a bid to minimize the steric and/or electronic repulsion. The arylthiopiperidin-4-ones exhibit significant antibacterial activity against Staphylococcus aureus, Vibrio cholerae, Salmonella typhi, and Escherichia coli and antifungal activity against Candida albicans and Aspergillus niger.     

Thermogravimetric analysis of different molar mass ammonium cations intercalated different cationic forms of montmorillonite

Different cationic forms of montmorillonite, mainly K-, Na-, Ca- and Mg-montmorillonites were intercalated in this study via ion exchange process with mono-, di-, and triethanolammonium cations. The developed samples were characterized by TG, XRD, and CHNS techniques. Thermogravimetric study of ammonium-montmorillonites shows three thermal transition steps, which are attributable to the volatilization of the physically adsorbed water and dehydration, followed by the decomposition of the intercalated ammonium cations and dehydroxylation of the structural water of the modified clay, respectively, while untreated and cationic forms of montmorillonite showed only two decomposition steps. The type of ammonium cation has affected both desorption temperature (Position) and the amount of the adsorbed water (intensity). XRD results show a stepwise change in the crystallographic spacings of montmorillonite with the molar mass of ammonium cation, reflecting a change in the structure of the clay. CHNS data confirm the intercalation of ammonium cations into the interlayer space of montmorillonite and corroborate the effect of the molar mass of ammonium cation on the amount adsorbed by the clay.     

Synthesis,spectroscopic investigations,antioxidants and DNA binding studies of a charge transfer of benzimidazole with 4-methylbenzenesulfonic acid

A new charge transfer (CT) complex benzimidazolium-4-methylbenzenesulfonate formed between benzimidazole and 4-methylbenzenesulfonic acid has been studied spectrophotometrically in methanol at room temperature. The binding of the novel CT complex with calf thymus DNA has been investigated by adsorption spectrum, the establish the ability of the CT complex for its interaction with the chosen DNA. The elemental stiochiometry and the X-ray crystallographic structure of the complex were studied, showing the significance of sulfonate anion in holding stability. Powder XRD confirms the crystalline nature of the compound. NMR signals explicitly confirmed the molecular structure crystal. Antioxidant activity of the CT complex was found to be potent. TG-DTA studies also proves the stability of the synthesized complex.     

Biological evaluation of redox stable cisplatin/Cu(II)-DNA adducts as potential anticancer agents

A series of non-enolizable β-diketonate-based copper(II) complexes with LCuCl₂ [L = Knoevenagel condensates of curcumin (Salcimine) and methylacetoacetate (SalMaA)-based Schiff bases] chromospheres as functional models of chemotherapy drug cisplatin were investigated for their covalent interaction with herring sperm DNA. The synthesis and structural characterization of 1a and 1b have been reported in our previous article. However, their DNA interactions and cytotoxicity properties were not studied. These analyses have been carried out mainly through electrochemical techniques supplemented with spectral, relative viscosity, gel electrophoresis techniques, and AGS cancer cells using MTT assay. The cytotoxic activities of the ligand, curcumin-based copper complex, and cisplatin were tested against the AGS cancer cell line under similar experimental conditions showing that the complex exhibited cancer cell inhibitory rate closer to cisplatin even at low concentration. This was also seen in the docking of the Cu-complex onto a rich guanine B-DNA decamer, where a Cu–N3_(guanine) interaction instead of Pt-N7 as cisplatin is detected. The obtained results in this study prove that these complexes could be a promising substitute for cisplatin as a new family of non-platinum-based anticancer metallo-drugs after in vivo tests on animal models.     

Kinetics of the outer-sphere oxidation of thiourea by heteropoly-α<Subscript>2</Subscript>-17-tungsto-1-vanadodiphosphate anion

Kinetics of the oxidation of thiourea (tu) by heteropoly-α₂-17-tungsto-1-vanadodiphosphate anion, α₂-[P₂V^VW₁₇O₆₂]^7?, have been studied spectrophotometrically in aqueous acidic medium at 25 °C. At low pH (2.4–3.0), the neutral form of tu is the only reactive species. At higher pH (4.2–4.9), both neutral and deprotonated forms of tu participate in the reaction. The observed mixed-order kinetics suggest two parallel reactions: one in which the order in [tu] is unity, and a second in which it is two. In both cases, the order in [α₂-[P₂V^VW₁₇O₆₂]^7?] is unity. Based on the kinetic studies, a mechanism is proposed, in which a second-order proton-coupled electron transfer involving NH₂CSNH₂ and α₂-[P₂V^VW₁₇O₆₂]^7? proceeds through a sequential electron transfer, followed by proton transfer such that the reaction is an “activation-controlled” outer-sphere electron transfer process. By applying the Marcus equation, the self-exchange rate constants for the couples \({\text{NH}}_{2} {\text{CSNH}}_{2}^{ \cdot + }\)/NH₂CSNH₂ and α₂-[P₂V^VW₁₇O₆₂]^7?/α₂-[P₂V^IVW₁₇O₆₂]^8? were evaluated.     

Structure-reactivity relationship of piperidine nitroxide: electrochemical, ESR and computational studies

We have synthesized several nitroxides with different substituents which vary the steric and electronic environment around the N-O moiety and have systematically investigated the role of substituents on the stability of the radicals. Our results demonstrated the reactivity toward ascorbate correlates with the redox potential of the derivatives. Furthermore, ab initio calculations also indicated a correlation between the reduction rate and the computed singly occupied molecular orbital-lowest unoccupied molecular orbital energy gap, but not with solvent accessible surface area of the N-O moiety, supporting the experimental results and suggesting that the electronic factors largely determine the radicals' stability. Hence, it is possible to perform virtual screening of nitroxides to optimize their stability, which can help to rationally design novel nitroxides for their potential use in vivo.     

On-wafer thermomechanical characterization of a thin film polyimide formed by vapor deposition polymerization for through-silicon via applications: Comparison to plasma-enhanced chemical vapor deposition SiO2

Thin-film polyimides were prepared by solvent-less vapor deposition polymerization (VDP) from pyromellitic dianhydride and 4,4′-oxydianiline at 200 °C for liner dielectric formation of vertical interconnects called through-silicon vias (TSVs) used in three-dimensionally stacked integrated circuit (3DICs). FTIR, synchrotron XPS, and TDS were employed for determining the imidization ratio, and in addition, the mechanical properties, coefficient of thermal expansion and Young's modulus, of the VDP polyimide were characterized on Si wafers. The VDP polyimide exhibited extremely high conformality, beyond 75%, toward high-aspect-ratio deep Si holes, compared with conventional SiO₂ prepared by plasma-enhanced chemical vapor deposition. The adhesion between the VDP polyimide and Si wafer was enhanced by an Al-chelate promotor. Remarkably, the VDP polyimide TSV liner dielectrics showed much less thermomechanical stresses applied to the Si surrounding the TSVs than the plasma-chemical vapor deposition SiO₂. The small keep-out zone is expected for scaling down highly reliable 3DICs for the upcoming real artificial intelligence society.     

Metal based pharmacologically active agents: Synthesis,structural elucidation,DNA interaction,in vitro antimicrobial and in vitro cytotoxic screening of copper(II) and zinc(II) complexes derived from amino acid based pyrazolone derivatives

The paper presents the synthesis of complex combinations of Cu(II) and Zn(II) with Schiff base obtained by the condensation reaction of 4-aminoantipyrine with benzaldehyde and 2-amino-3-methyl-butanoicacid. Structural features of synthesized compounds were determined by analytical and spectral techniques. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied by spectroscopic methods and viscosity measurements. Experimental results indicated the ability of the complexes to form adducts with DNA and to distort the double helix by changing the base stacking. Oxidative DNA cleavage activities of the complexes were studied with supercoiled (SC) pUC19 DNA using gel electrophoresis. The in vitro antimicrobial screening effects of the investigated compounds were monitored by the disk diffusion method. The synthesized Schiff base complexes exhibited higher antimicrobial activity than the respective free Schiff base. The in vitro cytotoxicity of synthesized complexes against Ehrlich ascites carcinoma (EAC) tumor model was investigated using trypan blue dye exclusion assay. The complexes possessed significant cytotoxic activity.