SEED MEDIATED SYNTHESIS OF HEXAGONAL S-DOPED ZnO NANOROD AND ITS PHYSICAL PROPERTIES

Sulfur-doped zinc oxide (S-ZnO) nanorod has been successfully synthesized via the seed-mediated hydrothermal method with different sulfur concentrations (0%, 1%, 2.5%). This research aims to study the influence of the concentration of sulfur on the structure, morphology, and optical properties of ZnO as a promising material in a wide range of applications. Crystal structure, morphology, and optical properties of the samples were characterized using X-Ray Diffraction (XRD), Field Emission Electron Scanning Microscopy (FESEM), and UV-Vis Spectroscopy, respectively. The XRD pattern shows the strongest peak at 2θ = 34.43° for crystal orientation of (002). The crystallinity properties of the S-ZnO sample are higher compared to the ZnO sample. The FESEM images of the 1% S-ZnO sample exhibit the highest nanorod density arrangement. The optical absorbance of the higher sulfur dopant possesses a higher optical absorption peak on the UV-Vis spectrum. The results indicate that S doping to ZnO can alter the structural, morphological, and optical properties of ZnO.

Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

In vitro and in vivo applications of Euphorbia wallichii shoot extract-mediated gold nanospheres

The current study was designed to investigate the potential of Euphorbia wallichii shoot extract for reducting Au3+ and stabilizing gold nanoparticles. UV-visible spectra of gold nanoparticles showed obvious surface plasmon resonance peak at 548 nm. Microscopy (SEM and TEM) showed spherical dimensions, and the energy dispersive X-ray spectra displayed the strongest optical absorption peak for gold (Au) at 2.1 keV. Dynamic light scattering spectra represent polydispersed mixture with particulate diameter of 2.5–103.2 nm. The IR spectra confirm the potential functional groups of shoot extract responsible for the reduction of Au3+ to gold nanoparticles which exhibit tremendous antibacterial potential of 76.31%, 68.47%, 79.85%, 48.10%, and 65.53% against Escherichia coli, Staphylococcus aureus, Bacillus pumilus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, respectively. Gold nanoparticles showed markedly elevated fungicidal potency compared to the shoot extract alone against the tested fungal strains. IC50 for 2,2-diphenyl-1-picrylhydrazyl scavenging was 31.52, 18.29, and 15.32 µg/mL at 30, 60, and 90 min of reaction time, respectively. Both shoot extract and nanoparticles revealed 71% mortality at 100 µg/mL, with LD90 values of 310.56 µg/mL. Experimental mice acquired dose-dependent analgesia of 54.21%, 82.60%, and 86.53% when treated with gold nanoparticles at 50, 100, and 200 mg/kg bw. Inhibition of gastrointestinal muscular contraction was 21.16%, 30.49%, and 40.19% in mice feed with 50, 100, and 200 mg/kg bw, respectively.

COMPREHENSIVE STUDY OF SILVER NANOPARTICLES OBTAINED FROM PINUS ROXBURGHII OBTAINED BY GREEN SYNTHESIS CHARACTERIZATION AND ANTIMICROBIAL APPLICATIONS.

The increasing resistance of microorganisms against antibiotics threatens the microbiologist. Quantum dots are found to be an excellent antibacterial agent against P. aeruginosa. In the present study pinus roxburghii collected from the Mahabaleshwar region of Maharashtra, India. The plants have been washed and dried in the shade for 10- 15 days. The 5 gm dried plant powder was boiled in 100ml of double distilled water, whose extract is used for, The titration of 1mmol silver nitrate solution. The change in color from pale yellow to red wine and, optical absorption peak in UV studies at 420 nm confirms existence of quantum dots. The morphology of the nanoparticles studied by FE-SEM analysis reveals, the particle size of 100 ± 40 nm. A good antimicrobial activity of obtained quantum dots, againstp. aeruginosa is evidenced with 17 mm in diameter a zone of inhibition. As p aeruginosa causes infection in wounds burns this study has recommended the use of quantum dots in ointments, lotions, and skin creams for early and safe recovery.

Electronic Structural and Optical Properties of Multilayer Blue Phosphorus: A First-Principle Study

Using the density functional theory, we systematically calculated the stability, electronic, and optical properties of monolayer and multilayer blue phosphorus. The results show the structures are all dynamically stable, and the gaps decrease with an increase of the number of layers. An unexpected transformation from indirect to direct band gaps is also observed as the tensile strain increases. In addition, the optical properties indicate the optical absorption peak of the material is in the ultraviolet region.

ANTIBACTERIAL ACTIVITY OF SYNTHESIZED SILVER NANOPARTICLES BY SIMAROUBAGLAUCA AGAINST PATHOGENIC BACTERIA

Objective: The present study outline the plant-mediated synthesis of silver nanoparticles (AgNPs) using leaf extract Simaroubaglauca, which act as both reducing and stabilizing agent.Methods: Formation of silver nanoparticles was confirmed by primarily by Ultraviolet/visible spectroscopy. X-ray diffraction studies revealed the crystallinity of the nanoparticles. The scanning electron microscopy was carried out to determine the mean particle size, as well as the morphology of the NPs and the composition of elements, was studied with Energy Dispersive X-ray analysis (EDS).Results: The silver nanoparticles were spherical in shape with a mean size of 23 nm. The EDS showed strong optical absorption peak at 3keV and it was confirmed the formation of AgNPs. The synthesised AgNPs further utilized for the evaluation of antibacterial activity and shown significant antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Enterobacter and Klebsiella pneumonia at 50 µg/ml and 100µg/ml concentrations.Conclusion: The synthesised silver nanoparticles have been characterised by UV-vis, SEM-EDAX and XRD to determine the sizes and shapes of the silver nanoparticles.

Fabrication of Metal Nanoparticle Arrays in the ZrO2(Y), HfO2(Y), and GeOx Films by Magnetron Sputtering

The single sheet arrays of Au nanoparticles (NPs) embedded into the ZrO2(Y), HfO2(Y), and GeOx (x≈2) films have been fabricated by the alternating deposition of the nanometer-thick dielectric and metal films using Magnetron Sputtering followed by annealing. The structure and optical properties of the NP arrays have been studied, subject to the fabrication technology parameters. The possibility of fabricating dense single sheet Au NP arrays in the matrices listed above with controlled NP sizes (within 1 to 3 nm) and surface density has been demonstrated. A red shift of the plasmonic optical absorption peak in the optical transmission spectra of the nanocomposite films (in the wavelength band of 500 to 650 nm) has been observed. The effect was attributed to the excitation of the collective surface plasmon-polaritons in the dense Au NP arrays. The nanocomposite films fabricated in the present study can find various applications in nanoelectronics (e.g., single electronics, nonvolatile memory devices), integrated optics, and plasmonics.

The Optical Properties of Doped Silicon Nanotubes

We perform the first-principles calculations within the framework of density functional theory to determine the electronic structure and optical properties of P-doped and B-doped silicon nanotubes. The results indicate that the electronic structure and optical properties of P-doped and B-doped silicon nanotubes are sensitive to the impurity composition. In particular, when doped with P or B, obviously the band gap decreases and the conductivity enhanced, the P-doped and B-doped silicon nanotubes displays a closer band structure and the unit cell volume of doped silicon nanotubes increased than before doping, the change depends on the doping charge and Si-Si bond length dSi-Si. Moreover, the dielectric constant decreases and increased when doped P and B, the optical absorption peak obviously has a blue shift and red shift respectively. The calculated results provide important theoretical guidance for the applications of Uv detector and the solar cell in optical detectors.

First-Principle Study on the Hexagonal Phase Properties for ZnO under High-Pressure

The evolution regularity of the optical properties and electronic structure for ZnO hexagonal phase is studied under high-pressure, by using first-principles plane wave pseudo-potential method. The method is based on density functional theory (DFT) within the generalized gradient approximation (GGA) approaches. The calculation reveals that the valence band and the conduction band move to the direction of low energy and the direction of high energy by an increase of pressure, respectively, and thus the band gap is enlarged. The results of calculate also show that the energy band structure of ZnO hexagonal phase changes and the band gap is broadened with the increasing of pressure, which results in the move of the optical absorption margin and the optical absorption peak towards the aspect of the high energy.

First-Principles Calculation of Tetragonal Phase Properties of ZnO under High-Pressure

First-principles plane wave pseudopotential method based on the density functional theory is used to study of the evolution rule of the optical properties and electronic structure for ZnO tetragonal phase under different pressure. The results show that the chemical bond between zinc and oxygen is shortened with the increase of the external pressure, while the increase of orbital hybridization between the zinc atom and the oxygen atom. The calculations also show that the band structure of ZnO tetragonal phase changes with the increase of the pressure, and the band gap is broadened, which causes that the optical absorption margin and the optical absorption peak move to the direction of high energy.