Perturbations for linear difference equations

In this paper we study boundary value problems for perturbed second-order linear difference equations with a small parameter. The reduced problem obtained when the parameter is equal to zero is a first-order linear difference equation. The solution is represented as a convergent series in the small parameter, whose coefficients are given by means of solutions of the reduced problem.     

Design and numerical analysis of a gold-coated photonic crystal fiber based refractive index sensor

Optical and Quantum Electronics - Optical sensors are very attractive in chemical and bio-chemical applications due to some unique characteristics, such as immunity to electromagnetic interference...     

Effect of functionalized multi-walled carbon nanotubes with poly(N-vinyl pyrrolidone-co-2-acrylamido-2-methyl-1-propanesulfonic acid) on the release of tramadol hydrochloride

Multi-walled carbon nanotubes(MWCNTs) were grafted with poly(N-vinyl-2-pyrrolidone) and with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) at different compositions by using γ-rays technique as initiator. The MWCNTs, MWCNT-graft-PNVP, MWCNT-graft-PAMPS and MWCNTs-graft-P(NVP-co-AMPS) were characterized by Fourier transform infra red(FTIR) spectroscopy, X-ray diffraction(XRD), thermal gravimetric analysis(TGA), elemental analysis and high-resolution transmission electron microscopy(HR-TEM). The results indicated that the grafting processes of PNVP, PAMPS and P(NVP-co-AMPS) occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride(TH) was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid(SGF, p H = 1.2) and simulated intestinal fluid(SIF, p H = 7.4) at 37 °C. Controlled release of TH from grafted MWCNTs was investigated. The outcome results suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and p H level of the simulated biological fluids.     

The Profile of Plasma Free Amino Acids in Type 2 Diabetes Mellitus with Insulin Resistance: Association with Microalbuminuria and Macroalbuminuria

Applied Biochemistry and Biotechnology - Altered plasma levels of branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) may predict the development of insulin resistance and other type...