Thia-Michael Addition in Diverse Organic Synthesis

Thia-Michael addition reactions are significant for organic syntheses of important class of compounds to form C-S bond and its derivatives. It shows the prominent feature in medicinal field and material science. This review is focused on various methods towards thia-Michael adducts using Michael addition of sulfur containing electron rich species (Michael donor) on electron poor olefins (Michael acceptor). The C-S bond is ideal of making bioactive molecules generalized for the synthesis of various drug molecules and applied in field as insect sprays and polymer substances which are common for daily life. Due to the importance of C-S bond in recent years, novel methods for C-S bond formation were developed, which are more convenient with environment

Stable Field Emission from Layered MoS2 Nanosheets in High Vacuum and Observation of 1/f Noise

Field emission and current noise of hydrothermally synthesized MoS2 nanosheets are investigated in ultra-high-vacuum and industrially suited high-vacuum conditions. The study reveals that the emission turn-on field is pressure dependent. Moreover, the MoS2 nano‐sheets exhibit more stable field-electron emission in high- vacuum than in ultra-high-vacuum conditions. The investigations on field-emission current fluctuations show features of 1/f-type noise in ultra-high-vacuum and high-vacuum conditions, attributed to adsorption and desorption processes. The post-field-emission results indicate the MoS2 nanosheets are a robust field emitter in high-vacuum conditions

Investigation of growth mechanism for highly oriented TiO2 nanorods: the role of reaction time and annealing temperature

Titanium dioxide (TiO2) is a versatile and inexpensive material for extended applicability in several scientific and technological fields including photo-catalysis for industrial waste treatment, energy harvesting, and hydrogen production. In this work, we report the synthesis of TiO2 thin film using hydrothermal method and investigations on the influence of reaction time and annealing temperature on growth mechanism of the TiO2 nanorods. The synthesized TiO2 films were studied by using UV–visible spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscope and energy-dispersive X-ray spectroscopy (EDS). The XRD and Raman measurements revealed the formation of defect free and pure tetragonal TiO2 rutile phase. The TiO2 thin films show absorption band edge at around 420 nm in the UV–visible spectrum and exhibit direct band gap value of 2.9 eV. The TiO2 nanorods are demonstrated to grow randomly on the FTO substrate with changing reaction times but grow uniformly in a flower-like pattern with increasing annealing temperature. Investigation of the field emission properties of TiO2 thin films (tested as field-emitter array) estimates the turn-on and threshold field at 4.06 and 7.06 V/µm at 10 and 100 µA/cm2, respectively

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 degrees C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2-30 walls with an inner diameter of 3-8 nm. Raman spectrum analysis shows G-band at 1580 cm(-1) and D-band at 1340 cm(-1). The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm(2) at 1.2V/mu m), low turn-on field (0.6 V/mu m) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron source

Molybdenum Doped SnO2 Thin Films as a Methanol Vapor Sensor

The molybdenum doped SnO2 thin films were synthesized by conventional spray pyrolysis route and has been investigated for the methanol vapor sensing. The structural and elemental composition analysis of thin films was carried out by X- ray diffraction and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDAX).The XRD spectrum revealed that the thin films have the polycrystalline nature with a mixed phase comprising of SnO2 and MoO3. The scanning Electron Microscopy (SEM) clears that the surface morphology observed to be granular, uniformly covering the entire surface area of the thin film. The methanol vapor sensing studies were performed in dry air at the different temperatures. The influence of the concentration of Molybdenum and operating temperature on the sensor performance has been investigated

Galvano static deposition of conducting poly (o-toluidine -co-o-anisidine) coating on low carbon steel and its corrosion performance

Conducting poly(o-toluidine -co-o-anisidine) coatings were synthesized on low carbon steel by electrochemical polymerization of o-toluidine and o- anisidine in aqueous oxalic acid by using galvano static method. The characterization of these coatings were carried out by using Scanning electron microscopy. The corrosion protection performance of these coatings were evaluated by using Potentiodynamic polarization technique. It was found that uniform and adherent conducting poly (o-toluidine -co-oanisidine)coating can be obtained on low carbon steel using galvano static technique. The potentiodynamic polarization study reveals that the coating offers significant corrosion protection to low carbon steel in acidic medium