Electrochemical determination of methylparaben with manganese ferrite/activated carbon-modified electrode

Journal of Materials Science: Materials in Electronics - Manganese ferrite/rice husk-derived activated carbon (MF/AC) was synthesized in a coprecipitation process followed by hydrothermal...     

Polymer-based nanoparticles for the delivery of nucleoside analogues

Nucleoside analogues, together with nucleobases and nucleotide analogues, are commonly used in the treatment of cancer and viral infections. In both cases, they act as antimetabolite agents and interfere with the synthesis of cellular or viral nucleic acids. However, the need of high doses due to the rapid elimination of these compounds, to their poor activation, and/or to their non-specific distribution, often leads to side effects and resistances. The present paper aims to review the different types of polymer nanoparticles which have been designed as drug delivery devices to address these issues. Thus, poly(alkylcyanoacrylate) nanoparticles have been demonstrated as potential carriers for antiviral nucleoside analogues, especially for anti-HIV agents, regarding both intravenous and oral routes. Nanoparticles based on polyesters such as poly(lactic acid) and poly(lactide-co-glycolide) have been used as nanocarriers for nucleosides analogues too, and especially for their ocular delivery. Albumin has shown interesting properties in the design of nanoparticles for the same application, but also for the oral administration of anticancer analogues. Finally, new hydrophilic nanoparticles consisting of cross-linked polymer network ('Nanogels') open the perspective to deliver nucleoside analogues within their active triphosphate form.     

Tracking control of a three-wheeled omnidirectional mobile manipulator system with disturbance and friction

This paper proposes a tracking control method for a three-wheeled omnidirectional manipulator system (OMMS) with disturbance and friction. The OMMS is separated into two subsystems, a three-wheeled omnidirectional mobile platform (OMP) and a selective compliant articulated robot for assembly (SCARA) type of manipulator. Therefore, two controllers are designed to control the OMP and the manipulator system. Firstly, based on a kinematic modeling of the manipulator, a kinematic controller (KC), combined with an integral sliding mode controller (ISMC), is designed for the end-effector of the manipulator to track a desired trajectory with the desired angular velocity vector of links. Secondly, a differential sliding mode controller (DSMC) based on a dynamic modeling of the OMP with force external disturbances is proposed to obtain control inputs moving the OMP so that the manipulator tracks the desired posture without singularity. The system stability is proven using Lyapunov stability theory. The simulation and experimental results are presented to illustrate the effectiveness of the proposed controllers in the presence of disturbance and friction.     

Railroad tracks: a potential source of ignition in hazardous ( classified) locations

This article uses a case history to illustrate how railroads are a potential source of ignition in hazardous (classified) locations. It will provide an overview of industry standards, design requirements, and operating procedures to ensure proper isolation, bonding, and grounding of railroad tracks and railcars at loading/unloading facilities.     

A Comparative Study of Hydroxyapatite- and Alumina-Based Catalysts in Dry Reforming of Methane

The dry reforming of methane over hydroxyapatite- and alumina/magnesia (commercial Pural MG 30)-supported nickel catalysts was investigated. The catalytic performance of the catalysts prepared with fresh supports highly depended on the basicity, the metal-support interaction, and the metal particle size. Calcination of the supports at 1200 °C for 5 h made the catalysts less active because of specific surface area reduction and basicity destruction. However, this treatment allowed avoiding any further catalyst deactivation by thermal sintering and maintained excellent catalytic stability over 300 h of time-on-stream. These tests under simulated industrial conditions (high contact time and long time-on-stream) showed the competitiveness of the prepared catalysts in this important catalytic process.     

Fluidic laser beam shaper by using thermal lens effect

Laser measurement and laser processing techniques have been gaining strong attention from various applications. This research aims at the development of a fluidic laser beam shaper, and in order to fulfill the objective, thermal lens effect characteristics are studied. This phenomenon has the optical property of a divergent lens since the refractive index distribution on the optical axis is formed when a liquid is irradiated. In this research, effects of the pump power and the propagation distance to the probe beam profile are investigated experimentally and theoretically, with the purpose of developing a fluidic laser beam shaper. It is indicated that, by controlling some parameters in thermal lens system such as the pump power (in the regime of linear optics) and absorption coefficient, an input Gaussian beam can be converted into a flat-top beam profile. The relationship between the distance to obtain the flat-top beam, the pump power and absorption coefficient is investigated to show the flexibility of the fluidic laser beam shaper in many fields of laser application.     

Y2O3:Eu3+ phosphor: a novel solution for an increase in color rendering index of multi-chip white LED packages

Abstract

In this study, a novel compound is synthesized by adding the red-emitting Y₂O₃:Eu³⁺ dopant to conformal phosphor package (CPP) or in-cup phosphor package (IPP), to be employed as a component in multi-chip white LEDs lamps (W-LEDs). It was found that this solution can enhance the color rendering index (CRI) of W-LEDs that have correlated color temperatures of 5600 K through 8500 K to more than 86. Besides, the impacts of the Y₂O₃:Eu³⁺ phosphor on the attenuation of light through the phosphor layers, CPP and IPP, are also demonstrated based on the Beer–Lambert law and Mie theory. These results provide important information for producing W-LEDs with higher CRI.