Structure,morphology and I–V characteristics of thermally evaporated LaAlO3 nanostructured thin films

Journal of Materials Science: Materials in Electronics - Nanostructured perovskite LaAlO3 thin films with thickness of 50 nm, 100 nm, and 150 nm were prepared using...     

The effect of inflation‐induced demand and trade credit on ordering policy of exponentially deteriorating and imperfect quality items

This paper develops an inventory model for exponentially deteriorating and imperfect quality items when a trade credit is offered by the supplier. As it has been seen that the changing rates of inflation do not just have an effect on the ordered quantity but they also stimulate the demand for products, so this paper considers the combined effect of inflation, deterioration, imperfect quality and ‘’ trade credit policy on the economic ordering policy using a discounted cash flow (DCF) approach. In the study, mathematical models are derived under two different circumstances, i.e., Case I: When the discount offered by the supplier with a condition of making the payment by a specified period, M₁ is accepted; and Case II: Discount is not taken and instead the payment is made by the end of the full credit period M (M > M₁). Finally, a numerical example demonstrating the applicability of the proposed model has been included.     

Pseudospectral methods for solving infinite-horizon optimal control problems

An important aspect of numerically approximating the solution of an infinite-horizon optimal control problem is the manner in which the horizon is treated. Generally, an infinite-horizon optimal control problem is approximated with a finite-horizon problem. In such cases, regardless of the finite duration of the approximation, the final time lies an infinite duration from the actual horizon at t=+∞. In this paper we describe two new direct pseudospectral methods using Legendre–Gauss (LG) and Legendre–Gauss–Radau (LGR) collocation for solving infinite-horizon optimal control problems numerically. A smooth, strictly monotonic transformation is used to map the infinite time domain t∈[0,∞) onto a half-open interval τ∈[−1,1). The resulting problem on the finite interval is transcribed to a nonlinear programming problem using collocation. The proposed methods yield approximations to the state and the costate on the entire horizon, including approximations at t=+∞. These pseudospectral methods can be written equivalently in either a differential or an implicit integral form. In numerical experiments, the discrete solution exhibits exponential convergence as a function of the number of collocation points. It is shown that the map ?:[−1,+1)→[0,+∞) can be tuned to improve the quality of the discrete approximation.     

Synthesis and characterization of polyacrylamide‐grafted coconut coir pith having carboxylate functional group and adsorption ability for heavy metal ions

The present investigation was undertaken to evaluate the effectiveness of a new adsorbent prepared from coconut coir pith (CP), a coir industry‐based lignocellulosic residue in removing metal ions from aqueous solutions. The adsorbent (PGCP‐COOH) having a carboxylate functional group at the chain end was prepared by grafting polyacrylamide onto CP using potassium peroxydisulphate as an initiator and in the presence of N,N′‐methylenebisacrylamide as a crosslinking agent. The adsorbent was characterized by infrared (IR) spectroscopy, thermogravimetry (TG), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and potentiometric titration. The adsorbent exhibits very high adsorption potential for the removal of Pb(II), Hg(II), and Cd(II) ions from aqueous solutions. The optimum pH range for metal ion removal was found to be 6.0–8.0. The adsorption process follows a pseudo‐second‐order kinetic model. The adsorption capacities for Hg(II), Pb(II), and Cd(II) calculated using the Langmuir isotherm equation were 254.52, 189.49, and 63.72 mg g^?1, respectively. Adsorption isotherm experiments were also conducted for comparison with a commercial carboxylate form cation exchanger. Different industry wastewater samples were treated by the PGCP‐COOH to demonstrate its efficiency in removing heavy metals from wastewater. The reusability of the PGCP‐COOH was also demonstrated using 0.2M HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3670–3681, 2007     

Plasma processing of PDMS based spinal implants for covalent protein immobilization,cell attachment and spreading

PDMS is widely used for prosthetic device manufacture. Conventional ion implantation is not a suitable treatment to enhance the biocompatibility of poly dimethyl siloxane (PDMS) due to its propensity to generate a brittle silicon oxide surface layer which cracks and delaminates. To overcome this limitation, we have developed new plasma based processes to balance the etching of carbon with implantation of carbon from the plasma source. When this carbon was implanted from the plasma phase it resulted in a surface that was structurally similar and intermixed with the underlying PDMS material and not susceptible to delamination. The enrichment in surface carbon allowed the formation of carbon based radicals that are not present in conventional plasma ion immersion implantation (PIII) treated PDMS. This imparts the PDMS surfaces with covalent protein binding capacity that is not observed on PIII treated PDMS. The change in surface energy preserved the function of bound biomolecules and enhanced the attachment of MG63 osteosarcoma cells compared to the native surface. The attached cells, an osteoblast interaction model, showed increased spreading on the treated over untreated surfaces. The carbon-dependency for these beneficial covalent protein and cell linkage properties was tested by incorporating carbon from a different source. To this end, a second surface was produced where carbon etching was balanced against implantation from a thin carbon-based polymer coating. This had similar protein and cell-binding properties to the surfaces generated with carbon inclusion in the plasma phase, thus highlighting the importance of balancing carbon etching and deposition. Additionally, the two effects of protein linkage and bioactivity could be combined where the cell response was further enhanced by covalently tethering a biomolecule coating, as exemplified here with the cell adhesive protein tropoelastin. Providing a balanced carbon source in the plasma phase is applicable to prosthetic device fabrication as illustrated using a 3-dimensional PDMS balloon prosthesis for spinal implant applications. Consequently, this study lays the groundwork for effective treatments of PDMS to selectively recruit cells to implantable PDMS fabricated biodevices.

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Optical and structural properties of Mg doped ZnO thin films by chemical bath deposition method

The chemical bath deposition method has often been employed to successfully deposit pure and Mg doped ZnO thin films on a glass substrate. The impact of Mg creates a strained stress in ZnO films affecting its structural and optical properties. XRD patterns revealed that all thin films possess a polycrystalline hexagonal wurtzite structure and Mg doped ZnO thin films (002) plane peak position is shifted towards a lower angle due to Mg doping. From the SEM image, it is understood that the Mg doped ZnO thin films are uniformly coated and are seen as dense rods like pillers deposited over the film. The energy dispersive X-ray analysis confirmed the presence of Mg in doped ZnO thin films. The transmittance spectra exhibit that it is possible for Mg doping to enhance ZnO thin films. The optical energy gap of the films was assessed by applying Tauc’s law and it is observed to show an increasing tendency with an improvement in Mg doping concentrations. The optical constants such as reflectance, index of refraction, extinction coefficient and optical conductivity are determined by using transmission at normal incidence of light by using wavelength range of 200–800 nm. In PL spectra, the band edge emission shifted to the blue with increasing amount of Mg doping.     

Focused Ultrasound Preconditioning for Augmented Nanoparticle Penetration and Efficacy in the Central Nervous System

Microbubble activation with focused ultrasound (FUS) facilitates the noninvasive and spatially‐targeted delivery of systemically administered therapeutics across the blood–brain barrier (BBB). FUS also augments the penetration of nanoscale therapeutics through brain tissue; however, this secondary effect has not been leveraged. Here, 1 MHz FUS sequences that increase the volume of transfected brain tissue after convection‐enhanced delivery of gene‐vector “brain‐penetrating” nanoparticles were first identified. Next, FUS preconditioning is applied prior to trans‐BBB nanoparticle delivery, yielding up to a fivefold increase in subsequent transgene expression. Magnetic resonance imaging (MRI) analyses of tissue temperature and K_trans confirm that augmented transfection occurs through modulation of parenchymal tissue with FUS. FUS preconditioning represents a simple and effective strategy for markedly improving the efficacy of gene vector nanoparticles in the central nervous system.     

1,3-Benzodioxole-Modified Noscapine Analogues: Synthesis,Antiproliferative Activity,and Tubulin-Bound Structure

Since the revelation of noscapine's weak anti-mitotic activity, extensive research has been conducted over the past two decades, with the goal of discovering noscapine derivatives with improved potency. To date, noscapine has been explored at the 1, 7, 6′, and 9′-positions, though the 1,3-benzodioxole motif in the noscapine scaffold that remains unexplored. The present investigation describes the design, synthesis and pharmacological evaluation of noscapine analogues consisting of modifications to the 1,3-benzodioxole moiety. This includes expansion of the dioxolane ring and inclusion of metabolically robust deuterium and fluorine atoms. Favourable structural modifications were subsequently incorporated into multi-functionalised noscapine derivatives that also possessed modifications previously shown to promote anti-proliferative activity in the 1-, 6′- and 9′-positions. Our research efforts afforded the deuterated noscapine derivative 14 e and the dioxino-containing analogue 20 as potent cytotoxic agents with EC₅₀ values of 1.50 and 0.73 μM, respectively, against breast cancer (MCF-7) cells. Compound 20 also exhibited EC₅₀ values of <2 μM against melanoma, non-small cell lung carcinoma, and cancers of the brain, kidney and breast in an NCI screen. Furthermore, compounds 14 e and 20 inhibit tubulin polymerisation and are not vulnerable to the overexpression of resistance conferring P-gp efflux pumps in drug-resistant breast cancer cells (NCI^ADR/RES). We also conducted X-ray crystallography studies that yielded the high-resolution structure of 14 e bound to tubulin. Our structural analysis revealed the key interactions between this noscapinoid and tubulin and will assist with the future design of noscapine derivatives with improved properties.     

EFFECT OF MAGNETIC FIELD-DEPENDENT VISCOSITY ON THERMAL CONVECTION IN A FERROMAGNETIC FLUID

This article deals with the theoretical investigation of the effect of magnetic field-dependent (MFD) viscosity on a layer of ferromagnetic fluid heated from below subject to a transverse uniform magnetic field. For a flat fluid layer contained between two free boundaries, an exact solution is obtained using a linear stability analysis and normal mode analysis method. For the case of stationary convection, the MFD viscosity has a stabilizing effect, whereas the departure of linearity in the magnetic equation of state has a destabilizing (or stabilizing) effect on the system under certain conditions. The critical wave number and critical magnetic thermal Rayleigh number for the onset of instability are also determined numerically for large values of buoyancy magnetization, and results are depicted graphically. The principle of exchange of stabilities is valid for the ferromagnetic fluid heated from below.