Sonochemical degradation of martius yellow dye in aqueous solution

The sonolytic degradation of the textile dye martius yellow, also known as either naphthol yellow or acid orange 24, was studied at various initial concentrations in water. The degradation of the dye followed first-order kinetics under the conditions examined. Based on gas chromatographic results and sonoluminescence measurements of sonicated aqueous solutions of the dye, it is concluded that pyrolysis does not play a significant role in its degradation. The chromatographic identification of hydroxy added species indicates that an OH radical induced reaction is the main degradation pathway of the dye. Considering the non-volatility and surface activity of the dye, the degradation of the dye most probably takes place at the bubble/solution interface. The quantitative and qualitative formation of the degradation intermediates and final products were monitored using HPLC and ESMS. The analytical results suggest that the sonolytic degradation of the dye proceeds via hydroxylation of the aryl ring and also by C-N bond cleavage of the chromophoric ring, either through OH radical attack or through another unidentified process. The identification of various intermediates and end products also imply that the degradation of martius yellow proceeds through multiple reaction pathways. Total organic carbon (TOC) analyses of the dye solutions at various times following sonication revealed that sonolysis was effective in the initial degradation of the parent dye but very slow in achieving mineralization. The slow rate of mineralization is likely to be due to the inability of many of the intermediate products such as, the carboxylic acids, to accumulate at the bubble (air/water) interface and undergo decomposition due to their high water solubility (low surface activity).     

Fragmentation pathways of deprotonated ortho-hydroxybenzyl alcohol

The ortho, meta, and para isomers of hydroxybenzyl alcohol can be unequivocally distinguished by the collision-induced dissociation mass spectra of their anions. The presence of a prominent peak at m/z 121 for an elimination of a dihydrogen molecule renders the ortho-isomer spectrum markedly different from those of its meta and para congeners. Investigations carried out with deuterium-labeled isotopologues of the ortho isomer verified that the labile hydrogen atom on the hydroxyl group and one of the benzylic hydrogen atoms are specifically removed in the formation of the m/z 121 ion. The ortho-isomer spectrum also showed a prominent peak at m/z 93. Experimental data indicated that the m/z 93 product ion originates either from a two-step H₂and CO elimination mechanism or from a direct loss of a HCHO molecule from the precursor anion. The intensity ratio of the m/z 93 and 94 peaks in the spectrum recorded from the m/z 124 ion generated from a sample of o-hydroxybenzyl alcohol dissolved in D₂O supported the notion that the direct HCHO loss is the more dominant pathway for the generation of the phenolate ion under low activation conditions. In contrast, the two-step mechanism becomes the more dominant pathway under high collisional activation conditions. The spectrum also showed a weak peak at m/z 105 for a water loss. Based on computational data, the m/z 105 ion generated in this way appears to be a composite generated from a common ion-neutral complex intermediate in which a hydroxyl anion is positioned equidistantly between one of the benzylic hydrogens and a nearby hydrogen atom of the benzene ring. Upon activation, the complex dissociates to form either a phenide or a quinone methide anion. The reaction forming a carbon dioxide adduct under ion-mobility conditions was used to support the proposed water-loss mechanism.     

Synthesis and characterization of functional photoactive organic-inorganic block copolymers of poly(methylphenylsilane) and disperse red 1 methacrylate and study of their optical and photophysical properties

Functional photoactive organic-inorganic block copolymers of poly(methylphenylsilane) (PMPS) and disperse red 1 methacrylate (DR1MA) were synthesized in a quartz tube using UV-technique. The synthesized block copolymers were characterized by FTIR, NMR, GPC and thermal analyses and studied for their optical and photoluminescence properties. The weight average and number average molecular weights of such a synthesized block copolymer are 2.47 × 10³ and 2.27 × 10³, respectively. The appearance of two glass transition temperatures indicated the synthesized polymers as block copolymers. The functional organic-inorganic block copolymers exhibited optical absorbance at 276 nm due to aromatic ring associated with both the blocks and at 325 nm due to σ-electron delocalization of Si-Si chain of PMPS block. Also, the optical absorbance appeared at 472 nm is due to combining the contribution of n-π* and first π-π* charge transfer electronic transition of the azobenzene chromophore of DR1MA unit. Two photoemissions were observed at 307 nm and 415 nm when such a polymer was excited at 275 nm. The photoluminescence was also observed at 415 nm when excited by 325 nm. The multi-emission spectra appeared between 510 nm to 580 nm are presumed to be due to exciton coupling between azobenzene chromophore of DR1MA and and Si-Si σ-conjugation of PMPS block. The synthesized copolymers are thermally stable up to 260°C. Such functional photoactive block copolymers may find novel optoelectronic application.     

Ultrasensitive electrochemical detection of nucleic acid based on the isothermal strand-displacement polymerase reaction and enzyme dual amplification

We describe an ultrasensitive electrochemical detection of DNA protocol based on the isothermal strand-displacement polymerase reaction (ISDPR) and enzyme dual amplifications. Target DNA triggered an ISDPR to produce numerous bi-functionalized duplex DNA complexes. Following an immuno-magnetic collection via an immunoreaction between the attached digoxin on the duplex DNA and the anti-digoxin antibody on the magnetic bead, horseradish (HRP) tracers were bound to the duplex DNA through a biotin–streptavidin interaction. The quantification of DNA was realized by square wave voltammetric detection of the enzymatic products with a screen-printed gold electrode. The voltammetric response was proportional to the concentration of DNA in the range of 0.1 fM–0.5 pM, and the limit of detection was estimated to be 0.06 fM. The new protocol showed great promise for simple, cost-effective, and quantitative gene analysis.     

Synthesis, characterization, and thermal study of polyaniline composite with the photoadduct of potassium hexacyanoferrate (II) involving hexamine ligand

The present paper involves the synthesis of polyaniline (PANI) composite with photoadduct of potassium hexacyanoferrate (II) involving hexamine as a ligand and cobalt chloride as a complexing agent via in situ oxidative polymerization by ammonium persulphate. The photoadduct has been synthesized by photoirradiation followed by substitution with the hexamine ligand. The final product has been isolated by using CoCl₂ as complexing agent. Viscosity average molar mass has been determined by viscosity method using Ostwald’s viscometer. The photoirradiation, substitution, and successful synthesis have been proved by recording pH, UV–visible spectra before and after irradiation, and FTIR of the photoadduct. The composite based on the synthesized photoadduct has been subjected to FTIR, X-ray diffraction, and SEM characterization techniques. Thermal analysis has been done by using TG and DSC technique. FTIR absorption peaks confirm the insertion of photoadduct in the backbone of PANI. SEM of the composite also supports its successful synthesis. The XRD of photoadduct shows crystalline structure, which has remained dominant in the composite, hence proving the successful synthesis of PANI composite with photoadduct. Thermal analysis shows high thermal stability of photoadduct which in turn has improved the thermal stability of PANI composite, therefore, shows the potential of composite for high-temperature application purposes.     

Symmetry structure and phase transitions

We study chiral symmetry structure at finite density and temperature in the presence of external magnetic field and gravity, a situation relevant in the early Universe and in the core of compact stars. We then investigate the dynamical evolution of phase transition in the expanding early Universe and possible formation of quark nuggets and their survival.     

Structural, thermal and conductive properties of Bi4−xMxV2O11 (M = La, Gd; 0 x 0.4) compounds

Bi_4−xM_xV₂O₁₁ (M = La, Gd) was prepared by solid state reactions. The amount of La and Gd in the (Bi_4−xM_xV₂O₁₁) was varied in the range of (0 x 0.4). The addition of La and Gd to Bi₄V₂O₁₁ electrolyte was found to stabilize the β crystalline phase for x 0.3. In addition, the phase transition corresponding β- to γ-phases are evident in the ionic conductivity plots as well as in XRD, DSC profiles of x 0.3 samples. The highest ionic conductivity was observed in Bi_3.9La_0.1V₂O₁₁ and Bi_3.8Gd_0.2V₂O₁₁ samples in the range of 10⁻³–10⁻⁴ S/cm for 700–500 °C. These results were supported by impedance spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC).     

Repurposing the antibacterial drugs for inhibition of SARS-CoV2-PLpro using molecular docking,MD simulation and binding energy calculation

Molecular Diversity - Papain-like protease (nsp-3; non-structural protein) of novel corona virus is an ideal target for developing drugs as it plays multiple important functions for viral growth...     

Linear balls and the multiplicity conjecture

A linear ball is a simplicial complex whose geometric realization is homeomorphic to a ball and whose Stanley–Reisner ring has a linear resolution. It turns out that the Stanley–Reisner ring of the sphere which is the boundary complex of a linear ball satisfies the multiplicity conjecture. A class of shellable spheres arising naturally from commutative algebra whose Stanley–Reisner rings satisfy the multiplicity conjecture will be presented.