Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Nanocatalysts and other nanomaterials for water remediation from organic pollutants

Piezocatalysis induced by polarization of piezoelectric materials is considered as an emerging technology in environmental cleanup. In this work, a piezoelectric material, Au nanoparticles modified BiVO4 (Au/BiVO4) is synthesized and its piezoelectric response is observed by piezo-response force microscopy. Au/BiVO4 is used as a bifunctional piezocatalyst for simultaneous removal of 4-chlorophenol (4-CP) and hexavalent chromium (Cr(VI)) upon ultrasonic vibration, with 91% and 83% of removal efficiency in 120 min, respectively. The piezocatalytic performance of Au/BiVO4 increases with the increase of ultrasonic power and the decrease of pH. The main active species for 4-CP oxidation and Cr(VI) reduction are determined to be OH and H2O2, respectively, since a significant formation rate of OH is estimated by a probe method, and a high amount of H2O2 accumulation is directly detected. This study provides understanding on the piezocatalysis mechanism and brings new insights for development of piezocatalysis for multifunctional environmental applications.

Efficient bifunctional piezocatalysis of Au/BiVO4 for simultaneous removal of 4-chlorophenol and Cr(VI) in water

Metal oxide semiconductors with a bandgap between 2 and 4 eV are an important class of compounds in the electronics industry and for photocatalysis. With the demand for these materials expanding ra...

Visible-Light-Active Doped Metal Oxide Nanoparticles: Review of their Synthesis, Properties, and Applications

We perform a general model-independent analysis of $b \to c \tau \bar{\nu}_\tau $ transitions, including measurements of $\mathcal{R}_D$, $\mathcal{R}_{D^*}$, their $q^2$ differential distributions, the recently measured longitudinal $D^*$ polarization $F_L^{D^*}$, and constraints from the $B_c \to \tau \bar{\nu}_\tau$ lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected $b \to c\tau\bar\nu_\tau$ observables, such as the baryonic transition $\Lambda_b \to \Lambda_c \tau \bar{\nu}_\tau$, the ratio $\mathcal{R}_{J/\psi}$, the forward-backward asymmetries ${\cal A}_\text{FB}^{D^{(*)}}$, the $\tau$ polarization asymmetries $\mathcal{P}_\tau^{D^{(*)}}$, and the longitudinal $D^*$ polarization fraction $F_L^{D^*}$. The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact. We also discuss the potential change due the very recently announced preliminary $\mathcal{R}_{D^{(*)}}$ measurement by the Belle collaboration.

/pdf/global-fit-to-b-to-c-tau-nu-transitions-25vzsh8q88.pdf

Global fit to $b \to c \tau \nu$ transitions

Piezocatalysis is a promising alternative of photocatalysis where the strained state of a piezoelectric material is exploited for electrochemical surface reactions under dark conditions. Among vari...

ZnSnO3 Nanoparticle-Based Piezocatalysts for Ultrasound-Assisted Degradation of Organic Pollutants

Nanoparticles are widely used in photocatalytic degradation of toxic chemicals and photodynamic therapy of cells that involve light-induced generation of reactive oxygen species (ROS) followed by R...

TiO2 Nanoparticles Co-doped with Nitrogen and Fluorine as Visible-Light-Activated Antifungal Agents

Visible light photocatalysis by TiO2 requires efficient doping of other elements with red-shifted band edge to the visible region. However, preparation of such TiO2 with tunable doping is challenging. Here we report a method of making nitrogen (N) and fluorine (F) codoped TiO2 nanoparticle with tunable doping between 1 and 7 at. %. The preparation of N, F codoped TiO2 nanoparticle involves reaction of colloidal TiO2 nanorods with an ammonium fluoride–urea mixture at 300 °C, and the extent of N/F doping is tuned by varying the amount of ammonium fluoride–urea and the reaction time. Resultant colloidal N, F codoped TiO2 nanoparticles show doping dependent shifting of the band edge from the UV to near-IR region, visible light induced generation of reactive oxygen species (ROS), and visible light photodegradation of bisphenol A. A colloidal form of doped TiO2 nanoparticle offers labeling of cells, visible light induced ROS generation inside a cell, and successive cell death. This work shows the potential adva...

https://pubs.acs.org/doi/pdf/10.1021/acsami.7b14025

Nitrogen and Fluorine Codoped, Colloidal TiO2 Nanoparticle: Tunable Doping, Large Red-Shifted Band Edge, Visible Light Induced Photocatalysis, and Cell Death.

Although the piezoelectric property of a BaTiO3 nanoparticle is routinely used in energy harvesting application, it can also be exploited for wireless cell stimulation and cell therapy. However, such biomedical application is rare due to limited availability of colloidal BaTiO3 nanoparticles of <100 nm hydrodynamic size with good piezocatalytic property and efficient biolabeling performance. Here, we report a colloidal form of a piezocatalytic BaTiO3-based nanorod of <100 nm hydrodynamic size that can offer wireless cell stimulation. The nanorod is prepared using a TiO2 nanorod as the template, and the resultant TiO2-BaTiO3-based composite nanorod is coated with a hydrophilic polymer shell. These nanorods can label cells and, under the ultrasound exposure, produce reactive oxygen species inside cells via piezocatalysis, leading to cell death. These nanorods can be used for wireless modulation of intracellular processes.

TiO2-Templated BaTiO3 Nanorod as a Piezocatalyst for Generating Wireless Cellular Stress.

Considering the recent experimental results on exclusive semileptonic $B$ meson decays showing sizable departure from their Standard Model prediction of lepton flavor universality and keeping ongoing and proposed non-standard Higgs searches in mind, we explore the charged current flavor observables ($\mathcal{R}_{D^{(*)}}$, $\mathcal{R}_{J/\psi}$), among other $b\to c\ell \nu$ transitions, in the presence of a relevant scalar current effective new physics operator. We use $B_c$ lifetime and predicted bounds on the branching fraction of $B_c \to \tau \nu$ decay as constraints. We show the allowed parameter space in terms of the real and imaginary parts of the corresponding Wilson coefficients for such interactions. Under the light of obtained results, we study the prospect of two benchmark models, rendering the Wilson coefficients real (Georgi-Machacek (GM)) and complex (Leptoquark (LQ)) respectively. We show that constraints from $b\to c\ell \nu$ on GM parameters are consistent with other flavor constraints on the model, if we drop the \Babar~results. Including those disfavors the model by more than $3\sigma$. On the other hand, one benchmark LQ scenario, which gives rise to a single scalar current effective interaction, is still allowed within $68\%$ confidence level, albeit with a shrunk parameter space.

Aritra Biswas

Papers

ZnSnO3 Nanoparticle-Based Piezocatalysts for Ultrasound-Assisted Degradation of Organic Pollutants

TiO2 Nanoparticles Co-doped with Nitrogen and Fluorine as Visible-Light-Activated Antifungal Agents

Nitrogen and Fluorine Codoped, Colloidal TiO2 Nanoparticle: Tunable Doping, Large Red-Shifted Band Edge, Visible Light Induced Photocatalysis, and Cell Death.

TiO2-Templated BaTiO3 Nanorod as a Piezocatalyst for Generating Wireless Cellular Stress.

$b \to c \ell \nu$ anomalies in light of extended scalar sectors