Optical thermometry using FIR of two close lying levels of different ions in Y2O3:Ho3+–Tm3+–Yb3+ phosphor

The possibility of combustion synthesized Ho³⁺–Tm³⁺–Yb³⁺ codoped Y₂O₃ phosphor as temperature sensor using fluorescence intensity ratio (FIR) technique under a 980 nm excitation has been reported. The variation in FIR of blue upconversion emissions generated from two closely spaced levels of the Tm³⁺ and Ho³⁺ ions (¹G₄ and ⁵F₃) as a function of temperature has been monitored up to 703 K. The maximum relative sensitivity has been found to be 3.38 × 10^?3 K^?1 which indicates that the present phosphor material can play a vital role for high optical thermometric purpose. The results imply that the FIR of two closely spaced levels of two different rare earth ions can also be used as temperature sensor.     

Fourth order finite difference method for sixth order boundary value problems

In the present paper, finite difference method is used to construct an approximate solution for the sixth order linear boundary value problems. Numerical examples are considered to illustrate the efficiency and convergence of the method. Numerical results show that proposed method is very effective, efficient, and fourth order accurate. Also fourth order accurate numerical value of second and fourth derivatives of solution, were obtained as by product of the proposed method.     

Performance analysis of symmetrical 10 Gbps colorless WDM-PON using subcarrier modulated downstream and wavelength converted upstream through RSOA

Here we have demonstrated a novel architecture of colorless wavelength division multiplexed-passive optical network (WDM-PON) and analyze its performance which is capable of transmitting 10 Gbps data symmetrically in both downstream and upstream. In this architecture downstream data is subcarrier modulated (SCM) using radio frequency (RF) as subcarrier and laser frequency as carrier with the help of a Mach–Zehnder modulator (MZM). For upstream data modulation an electro-absorption modulator, an optical coupler and reflective semiconductor optical amplifier (RSOA) are used. Upstream data is transmitted through wavelength conversion between pump wavelength and continuous wave light sent from central office (CO) using cross gain modulation (XGM) in RSOA. Pump wavelengths have separate wavelength band than the carrier's wavelength sent from optical network unit (ONU) and can be chosen any one in its band. Since carrier reuse scheme is implemented so all the ONUs are operates in colorless mode. Effect of ER of delay interferometer (DI) on output OCSR of DI for different input OCSR is performed for SCM data. Simulation is performed with all 16 downlink and 16 uplink channels having data rate of 10 Gbps having acceptable performance.     

Biodegradable thermoresponsive polymeric magnetic nanoparticles: a new drug delivery platform for doxorubicin

The use of nanoparticles as drug delivery systems for anticancer therapeutics has great potential to revolutionize the future of cancer therapy. The aim of this study is to construct a novel drug delivery platform comprising a magnetic core and biodegradable thermoresponsive shell of tri-block-copolymer. Oleic acid-coated Fe₃O₄ nanoparticles and hydrophilic anticancer drug “doxorubicin” are encapsulated with PEO–PLGA–PEO (polyethylene oxide–poly d, l lactide-co-glycolide–polyethylene oxide) tri-block-copolymer. Structural, magnetic, and physical properties of Fe₃O₄ core are determined by X-ray diffraction, vibrating sample magnetometer, and transmission electron microscopy techniques, respectively. The hydrodynamic size of composite nanoparticles is determined by dynamic light scattering and is found to be ~36.4 nm at 25 °C. The functionalization of magnetic core with various polymeric chain molecules and their weight proportions are determined by Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. Encapsulation of doxorubicin into the polymeric magnetic nanoparticles, its loading efficiency, and kinetics of drug release are investigated by UV–vis spectroscopy. The loading efficiency of drug is 89% with a rapid release for the initial 7 h followed by the sustained release over a period of 36 h. The release of drug is envisaged to occur in response to the physiological temperature by deswelling of thermoresponsive PEO–PLGA–PEO block-copolymer. This study demonstrates that temperature can be exploited successfully as an external parameter to control the release of drug.     

The origin of stacking modulations

The explanations for the origin of stacking modulated structures observed in as grown SiC crystals as well as during restacking transitions induced in short period structures by thermal annealing are reviewed.     

Efficient synthesis of the siderophore petrobactin via antimony triethoxide mediated coupling

Chemical synthesis of petrobactin, a siderophore for Bacillus anthracis, has been achieved via Sb(OEt)₃-mediated ester–amide exchange.     

Controllability of second‐order Sobolev‐type impulsive delay differential systems

In this paper, we study some controllability results for second‐order Sobolev‐type impulsive integrodifferential systems with finite delay. The results are obtained by using the concepts of measure of noncompactness and Mönch's fixed point theorem. Particularly, we consider the damping term y′(·) and find a control u such that the mild solution satisfies y(T) = y_T and . Finally, an application is given to illustrate the obtained results.     

The Kinetic Space of Multistationarity in Dual Phosphorylation

Journal of Dynamics and Differential Equations - Multistationarity in molecular systems underlies switch-like responses in cellular decision making. Determining whether and when a system displays...