Nano

A novel approach for phototherapy is proposed. The proposed method is based on cell apoptosis according to halting activation of cancer cell membrane receptor by exposure to UV light pulses without any side effect. In the proposed method, gold nanoparticles are directed to cancerous cells by conjugating their surface with specific ligands. UV light is created locally adjacent to cells around the gold nanoparticles. UV light is generated due to nonlinear interaction of visible light with gold nanoparticles because of enhancement in third order nonlinear effects. For example, by using 780 nm laser, 260 nm UV will be generated around the nanoparticle because of third harmonic generation process. As the generated UV is localized around the cell, there will be no side effect for other cells. We have numerically analyzed the proposed method by solving Maxwell's equation considering third order nonlinear susceptibility and dispersion behavior of permittivity by 3D nonlinear finite difference time domain using Newton–Raphson method. Simulation results for different geometries show that UV light will be generated around gold nanoparticle and it is maximum in hot spots where electric field enhancement occurs. Simulation results illustrate that there is neither UV irradiation side effect to healthy cells, nor harmful temperature rise.

PEG-encapsulated colloidal nanocrystal clusters (CNCs) have been synthesized via a one-step solvothermal process at a temperature of 230°C. The composition, phase, and morphology of these CNCs have been characterized by X-ray diffraction and transmission electron microscopy. Studies show that each particle is a cluster structure consisting of small primary iron oxide nanocrystals. Magnetic measurements reveal the superparamagnetic nature of these CNCs at room temperature. The CNCs with different sizes (80 nm or 95 nm) can be obtained by changing the time of reaction. The dispersibility and colloidal stability of these CNCs with PEG as the major surface group have also been discussed. In vitro cytotoxicity of these CNCs with different thickness PEG layer on HeLa cell has also been assayed. Cytotoxicity results reveal that the CNCs concentration and the incubation time can influence the cell viability, and the size of CNCs almost does not affect the cell viability.

Hydrogen storage capacity of a carbon nanotube (CNT) sample is investigated using Elastic Recoil Detection Analysis (ERDA) at constant hydrogen uptake pressure of 5 bar and different adsorption temperatures within 30°C–500°C. The results of hydrogen concentration versus temperature revealed three distinct temperature intervals in which a certain adsorption or desorption mechanism is dominant. Moreover, the results showed that hydrogen storage capacity of CNTs at the applied conditions of pressure and temperature is about 0.1 wt.% which is well below the DOE requirements for a viable hydrogen storage system. The physidesorption activation energy is calculated using the Arrhenius plot to be 6 kJmol^-1.

We have used the co-precipitation technique to synthesize nanocrystalline Co-doped CeO₂ dilute magnetic semiconductors with Co concentrations ranging from 0.0–0.07. X-ray diffraction patterns (XRD) demonstrate that all the samples display single phase cubic structure without any impurity phase. Average particle sizes calculated from XRD and transmission electron microscopy (TEM) studies showed a gradual decrease with increase in Co ions concentration. UV–visible optical spectroscopy measurements reflect an energy band gap, which decreases with the increasing concentration of dopant (x ≤ 0.03). Raman spectra show an intensity loss of classical CeO₂ vibration modes, which is an indication of considerable structural modifications and disorder in CeO₂ lattice. Magnetic measurements revealed that all the samples exhibit a weak ferromagnetism at room temperature.

Here we report a safer, easier, and quicker chemical route for synthesis of CdSe quantum dots (QDs), followed by their characterizations by UV/vis Spectroscopy (UV/vis), X-ray diffraction study (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and fluorescence (FL) spectroscopy. The average size of the quantum dots is 7.5 nm. Fluorescence study reveals that CdSe quantum dots emit green light when excited by optical source of wavelength of 550 nm or less.

Molecular dynamics simulations are carried out to examine the heterogeneous solidification of aluminum solution seeded by foreign boron-nitride nanotubes (BNNTs). The final structure indicates noticeably that Al atoms are concentrated to form incredible hierarchical nanostructures composed of coaxial and equidistant cylindrical shells with the BNNTs as the heterogeneous core. The structures of so-formed Al cylinders show strict structural matching and strong structural relevance with BNNTs. Heterogeneous solidification occurred on BNNTs follows a spiral nucleating mechanism. Heredity effect of these hollow cylinders can be clearly observed during the heterogeneous nucleation. The uniform internal potential field around BNNTs is found to be responsible for the formation of the coaxial cylindrical Al shells.

New ex situ polyaniline (PANI)/MnO₂-filled multiwalled carbon nanotubes (MWCNTs) nanocomposites using para-hydroxybenzene sulfonic acid (PHBSA) as a dopant and linker exhibit enhanced electrical conductivity and interfacial interaction. Strong and enhanced interfacial interaction was observed on the surfaces of the filled carbon nanotubes and PANI. Transmission electron microscope (TEM) demonstrated clearly the improved bonding at the interface compared to the nanocomposite without PHBSA.