Plasma splashing from Al and Cu materials induced by and Nd : YAG pulsed laser

Plasma splashing from Al and Cu target materials and the growth of thin films on Cu and Al, respectively, has been studied using a Q-switched Nd:YAG laser with a 1064-nm, 80-mJ, 8-ns pulse width as the source of ablation. The target kept rotating and the substrate, Cu for Al and vice versa, was placed at an angle of 15° with respect to the beam axis. During the laser-matter interaction, the targets absorbed thermal energy within the thermal region depth of 4.7 (1.1) nm, yielding an ablated skin depth of 6.7 (4.2) nm. The surface morphology of the exposed targets was studied by analyzing SEM micrographs obtained using a ZEISS SUPRA 35 VP. The obtained results are explained on the basis of different sputtering/ablation mechanisms. Comparatively severe damage forming a bigger crater is seen on the Al target surface in contrast to the crater on the Cu surface. This observation is correlated with the blustering effect and/or debris formation. Energy dispersive spectroscopy (EDX) of the substrates yielded the deposition of micrometric grain-size particle

Spectroscopic estimation of electron temperature and density of zinc plasma open air induced by Nd:YAG laser

The spectroscopic emission of zinc plasma along with CCD imaging profile has been studied. The zinc target has been irradiated with a Q-switched Nd:YAG laser (1064 nm, 290 mJ, 10 ns, 29 MW) in air at atmospheric pressure. The plasma emission is recorded with 100 ns integration time. Boltzmann plot method and Stark broadening profile of the transition line has been used to estimate the electron temperature (Te) and electron density (Ne) respectively. Estimated values of Te and Ne is in the range of (5700–6756) K and (1.6 × 1015-3.39 × 1015) cm-3 at three laser shots respectively

Multifunctional Silver-based Nanomaterials for Non-conventional Oral Cancer Therapy through Simultaneous LOX and Selective COX-2 inhibition

Neoplastic cells have co-opted inflammatory receptors and signaling molecules that potentiate inflammation. Activated inflammatory pathways lead to neo-angiogenesis, lymph-angiogenesis, immunosuppression, tumor growth, proliferation and metastasis. This cancer-sustaining inflammation is a critical target to arrest cancer growth. Multiple drug resistance, high cost, low oral bioavailability and serious side effects have rendered conventional cytotoxic chemotherapeutics less impressive. The aim of this research was to achieve cancer debulking and proliferation prevention by limiting ‘cancer-sustaining’ tumor niche inflammation through non-conventional oral approach employing anti-inflammatory agents and avoiding conventional cytotoxic agents. Synergistic anti-inflammatory agents, i.e. celecoxib as selective COX-2 inhibitor and montelukast as cysteinyl leukotriene receptor antagonist, were selected. Silver nanoparticles (AgNPs) were used as nanocarriers because of their efficient synergistic anti-neoplastic effects and excellent oral drug delivery potential. Specifically, selected drugs were co-conjugated onto AgNPs. Synthesized nanoparticles were then surface-modified with poly (vinyl alcohol) to control particle size, avoid opsonization/preferred cellular uptake and improve dispersion. Surface plasmon resonance analysis, particle size analysis, DSC, TGA, XRD, FTIR and LIBS analysis confirmed the successful conjugation of drugs and efficient polymer coating with high loading efficiency. In-vitro, the nanoparticles manifested best and sustained release in moderately acidic (pH 4.5) milieu enabling passive tumor targeting potential. In-vivo, synthesized nanoparticles exhibited efficient dose-dependent anti-inflammatory activity reducing the dose up to 25-fold. The formulation also manifested hemo-compatibility, potent anti-denaturation activity and dose-dependent in-vitro and in-vivo anti-cancer potential against MCF-7 breast cancer and Hep-G2 liver cancer cell lines in both orthotopic and subcutaneous xenograft cancer models. The anti-inflammatory nanoparticles manifested tumor specific release potential exhibiting selective cytotoxicity at cancerous milieu with slightly acidic environment and activated inflammatory pathways. The formulation displayed impressive oral bioavailability, sustained release, negligible cytotoxicity against THLE-2 normal human hepatocytes, low toxicity (high LD50) and wide therapeutic window. Results suggest promise of developed nanomaterials as hemo-compatible, potent, cheaper, less-toxic oral anti-inflammatory and non-conventional anti-cancer agents

Low-dimensional carrier statistics in nanostructures

The carrier statistics in a low-dimensional nanostructure with length in one or more of the three dimensions plummeting below carrier's De Broglie wavelength is investigated. The probability distribution, the Fermi level, intrinsic velocity, and energy of the carriers are sternly affected on reducing dimensionality from 3-dimensional (3-D) bulk configuration. The carrier statistics for degenerate and non-degenerate regimes for nanostructures is worked out with an emphasis to predict the ultimate carrier velocity in a high electric field. The general results presented are applicable to all materials once the carrier concentration and ambient temperature are identified

Nano-sized agglomerated Ni particles synthesized by a phase transformation method Multi-photons Trapping Stability within a Fiber Bragg Grating for Quantum Sensor Use

We propose an interesting result of the trapped multi photons distribution within a fiber Bragg grating. The trapped photons are con?ned by the potential well, which introduce the motion of photons in a ?ber Bragg grating a?ected by multi perturbations. The external perturbations are de?ned as series of nonlinear parametric in terms of potential energy. This in- vestigation is developed by using the nonlinear couple mode equations and under Bragg resonance condition where the initial frequency of the light, ?0 is the same value as the Bragg frequency, ?B . The results show that the higher perturbation series represents the potential well is much indi?erent of equilibrium. In applications, the perturbation can cause the trapped photons in- stability which introduces the escape photons from the potential well. The applications such as entangled photon source and quantum sensors can be performed

Open-gate liquid-phase sensor fabricated on undoped-AlGaN/GaN HEMT structure

Sensing responses of an open-gate liquid-phase sensor fabricated on undoped-AlGaN/GaN high-electron-mobility-transistor (HEMT) structure are investigated in aqueous solution. In air-exposed ambient, the open-gate undoped AlGaN/GaN HEMT shows the only presence of linear region of currents while Si-doped AlGaN/GaN shows linear and saturation regions of currents, very similar to those of gated devices. This seems to show that very low Fermi level pinning by surface states exists in undoped AlGaN/GaN sample compared to Si-doped sample. In aqueous solution, the typical current-voltage (I-V) characteristics of HEMTs with reasonably good gate controllability are observed. The potential of the AlGaN surface at the open-gate area is effectively controlled via aqueous solution by Ag/AgCl gate electrode. The open-gate undoped AlGaN/GaN HEMT structure is capable of distinguishing pH level in aqueous electrolytes and exhibits linear sensitivity, where high sensitivity of 1.9 mA/pH or 3.88 mA/mm/pH at drain-source voltage, VDS = 5 V is obtained. Due to large leakage current where it increases with the negative gate voltage, the Nernstian’s like sensitivity cannot be determined as what commonly reported in literatures. This large leakage current may be caused by the technical factors rather than the characteristics of the devices themselves. Suprisingly, although there is imperfection in the device preparation, the fabricated devices work very well in distinguishing the pH levels. Suppression of current leakage is likely to improve the device performance. The fabricated open-gate undoped-AlGaN/GaN structure is expected to be suitable for pH sensing application

Detection and investigation of carbon ions induced by ND:YAG laser using SSNTDS

A Q-Switched Nd:YAG laser pulse of pulsed width of 9~14 ns, wavelength of 1064 nm, repetition rate of 0.5 Hz, power of 1.1 MW and energy of 10 mJ has been used to ablate the 4N pure graphite target through IR lens. Solid state nuclear track detector (SSNTD) CR-39 has been used to calculate the energy of carbon ions produced as a result of laser ablation and the whole experiment has been performed under pressure ~10-3 Torr in stainless steel vacuum chamber. The minimum and maximum energy of carbon ions observed are 0.2 KeV to 250 KeV respectively

Carbon thin films deposition by KRF pulsed laser at different temperatures

The surface morphology of carbon thin films deposited at temperatures 20°C and 300°C have been done by Atomic Force Microscope (AFM). The 10,000 pulses of KrF Excimer laser of wavelength 248 nm, pulse energy 13-50 mJ and pulse width 20 ns was focused at an angle of 45° to ablate pure graphite target. Silicon (111) was used as a substrate to deposit carbon thin film and placed at distance of 15 mm from the target surface. The whole experiment has been performed under vacuum ~ 10-4 Torr in stainless steel vacuum chamber. The nature of bonding of carbon thin films deposited at different temperatures has been done by using technique Fourier Infrared Transformation Spectroscopy (FTIR). Results obtained from AFM and FTIR support each other and explain the effect of substrate temperature on thin films deposition

Thermodynamic equilibrium for nitrogen species discharge: comparison with global model

The equilibrium process of plasma nitrogen species by chemical kinetic reactions along various pressures is successfully investigated. The equilibrium process is required in industrial application to obtain the stable condition when heating up the material for having homogenous reaction. Nitrogen species densities is modeled by a continuity equation and extended Arrhenius form. These equations are used to integrate the change of density over the time. The integration is to acquire density and the reaction rate of each reaction where temperature and time dependence are imposed. A comparison is made with global model within pressure range of 1–100 mTorr and the temperature of electron is set to be higher than other nitrogen species. The results show that the chemical kinetic model only agrees for high pressure because of no power imposed; while the global model considers the external power along the pressure range then the electron and nitrogen species give highly quantity densities by factor of 3–5

Organo Opto-Electronics Study of Optical properties of Alpha and Nd:YAG Laser Irradiated Cellulose Nitrate Polymer

Abstract: Samples from cellulose nitrate ( CN-85) sheets of 0.3 mm thickness irradiated with low and high doses of alpha particles have been post exposed to Q-switched pulsed Nd:YAG laser. In this present work, the effect of laser irradiation on the structural properties of CN-85; have been investigated using absorption and fluorescence. The absorption spectra of only alpha irradiated and Nd:YAG laser irradiated samples are studied and optical band gap energy of the samples are calculated. Optical band gap energy measurements for high doses are more significant as compared to low doses. The increase in the band gap energy might be due to hardening of material which happens as a result of crosslinking of the polymer