Synthesis and applications of tungsten and vanadium oxides/oxyhydroxides in both bulk and nanoparticulate forms

The reactions of tungstic acid towards alkenes, alkynes, and nitriles were explored in order to determine the scope of its reactions with unsaturated hydrocarbons. The chemistry was found to be complex with small changes in substrates leading to significant changes in the products produced. Most reactions, but not all, resulted from strong acid catalysis. Dehydrogenation, dimerization, cyclotrimerization, oligomerization, and hydration reactions were observed. Single-step reactions to produce useful triazenes or to convert light petroleum fractions to diesel fuel, the Jacobsen rearrangement of alkyl benzenes, and the first non-enzymatic retro benzoin condensation were discovered. The products have potential applications in organic synthesis, industry, and medicine. The reduction of colloidal suspensions of vanadium bronze were found to produce suspensions of vanadium bronze nanoparticles while reactions with bulk materials produced bulk bronzes. Bimetallic oxides and oxyhydroxides of vanadium combined with aluminum, zirconium, yttrium, and lanthanum were successfully obtained through reaction of the aqueous vanadyl oxalate and the corresponding metal oxide or hydroxide. These materials have important applications in catalysis, pigments, and explosive sensing. In the latter respect, sensing systems for hydrogen peroxide detection utilizing colloidal vanadium bronzes, vanadyl solutions, and thin film of vanadium oxide materials were developed. Thin films of V10O24-12H2O were made successfully from a nanometric suspension of the material produced by reduction of peroxovanadic acid by oxalic acid. This film showed electrical conductivity and stability for long periods of time. All of the vanadium-containing systems tested showed rapid dramatic colors change after exposure to hydrogen peroxide exposure. Supporting the materials on porous alumina surfaces resulted in a significant enhancement of the sensitivity towards peroxide. Two of these sensing systems showed exceptional promise for sensor development due to their ability to regenerate their original color after hydrogen peroxide exposure ends. Kinetic analysis of color regeneration found it to be a first order reaction. The resting states of these two catalytic systems are the blue reduced vanadium compound. When exposed to hydrogen peroxide the materials adopt the red coloration of a vanadium hydroperoxide complex but once removed from hydrogen peroxide, the blue color slowly regenerates as the red color fades

Knowledge of Saudi parents toward the emergency management of avulsed permanent teeth: A cross-sectional survey

Introduction: Traumatic dentoalveolar injuries are frequent in children, affecting teeth, their supporting structures, and adjacent soft tissues. Parents are among the first people to deal with tooth avulsion among children at home or at play. This study, therefore, aimed to examine parental knowledge and attitudes about avulsed permanent teeth and their emergency treatment in children. Materials and Methods: A cross-sectional study was carried out with 274 parents of children receiving care at KKU College of Dentistry, Abha. Informed consent was obtained after explaining the nature of the study and data were collected using a self-administered questionnaire. Data were entered in MS Excel Sheet, and descriptive statistics were obtained. Results: Sixty-one percent of the parents reported dental trauma at home or school. 67.2% were not aware of the steps to be taken in tooth avulsion. The percentage for the source of information for avulsed tooth was a dentist (38.8%) and the internet (34.5%). 73.8% were unaware of the fact that permanent avulsed tooth can be replanted. 56.3% parents said that they would discard the knocked out tooth. Regarding knowledge about traumatic dental injuries 43.9% said it is imperative to know about it. Conclusion: This survey reflected the lack of awareness and adequate knowledge regarding the avulsed tooth. There is an imperative need for educating the parents regarding management of avulsed tooth permanent tooth

Increased Crystallization of CuTCNQ in Water/DMSO Bisolvent for Enhanced Redox Catalysis

Controlling the kinetics of CuTCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) crystallization has been a major challenge, as CuTCNQ crystallizing on Cu foil during synthesis in conventional solvents such as acetonitrile simultaneously dissolves into the reaction medium. In this work, we address this challenge by using water as a universal co-solvent to control the kinetics of crystallization and growth of phase I CuTCNQ. Water increases the dielectric constant of the reaction medium, shifting the equilibrium toward CuTCNQ crystallization while concomitantly decreasing the dissolution of CuTCNQ. This allows more CuTCNQ to be controllably crystallized on the surface of the Cu foil. Different sizes of CuTCNQ crystals formed on Cu foil under different water/DMSO admixtures influence the solvophilicity of these materials. This has important implications in their catalytic performance, as water-induced changes in the surface properties of these materials can make them highly hydrophilic, which allows the CuTCNQ to act as an efficient catalyst as it brings the aqueous reactants in close vicinity of the catalyst. Evidently, the CuTCNQ synthesized in 30% (v/v) water/DMSO showed superior catalytic activity for ferricyanide reduction with 95% completion achieved within a few minutes in contrast to CuTCNQ synthesized in DMSO that took over 92 min

Erratum: Hussain et al. Increased Crystallization of CuTCNQ in Water/DMSO Bisolvent for Enhanced Redox Catalysis. <i>Nanomaterials</i> 2021, <i>11</i>, 954

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