Locating Emergency Facilities Using the Weighted k-median Problem: A Graph-metaheuristic Approach

An efficient approach is presented for addressing the problem of finding the optimal facilities location in conjunction with the k-median method. First the region to be investigated is meshed and an incidence graph is constructed to obtain connectivity properties of meshes. Then shortest route trees (SRTs) are rooted from nodes of the generated graph. Subsequently, in order to divide the nodes of graph or the studied region into optimal k subregions, k-median approach is utilized. The weights of the nodes are considered as the risk factors such as population, seismic and topographic conditions for locating facilities in the high-risk zones to better facilitation. For finding the optimal facility locations, a recently developed meta-heuristic algorithm that is called Colliding Bodies Optimization (CBO) is used. The performance of the proposed method is investigated through different alternatives for minimizing the cost of the weighted k-median problem. As a case study, the Mazandaran province in Iran is considered and the above graph-metaheuristic approach is utilized for locating the facilities

Improved Inactivation Effect of Bacteria Fabrication of Mesoporous Anatase Films with Fine Ag Nanoparticles Prepared by Coaxial Vacuum Arc Deposition

We realize ultrarapid inactivation of bacteria by modifying fine Ag nanoparticles with uniform size on mesoporous anatase films with high surface areas

Effect of the mechanical activation on size reduction of crystalline acetaminophen drug particles

The decrease in particle size may offer new properties to drugs. In this study, we investigated the size reduction influence of the acetaminophen (C8H9O2N) particles by mechanical activation using a dry ball mill. The activated samples with the average size of 1 μm were then investigated in different time periods with the infrared (IR), inductively coupled plasma (ICP), atomic force microscopy (AFM), and X-ray diffraction (XRD) methods. The results of the IR and XRD images showed no change in the drug structure after the mechanical activation of all samples. With the peak height at full width at half maximum from XRD and the Scherrer equation, the size of the activated crystallite samples illustrated that the AFM images were in sound agreement with the Scherrer equation. According to the peaks of the AFM images, the average size of the particles in 30 hours of activation was 24 nm with a normal particle distribution. The ICP analysis demonstrated the presence of tungsten carbide particle impurities after activation from the powder sample impacting with the ball and jar. The greatest reduction in size was after milling for 30 hours

Voltammetric Determination of Homocysteine Using Multiwall Carbon Nanotube Paste Electrode in the Presence of Chlorpromazine as a Mediator

We propose chlorpromazine (CHP) as a new mediator for the rapid, sensitive, and highly selective voltammetric determination of homocysteine (Hcy) using multiwall carbon nanotube paste electrode (MWCNTPE). The experimental results showed that the carbon nanotube paste electrode has a highly electrocatalytic activity for the oxidation of Hcy in the presence of CHP as a mediator. Cyclic voltammetry, double potential step chronoamperometry, and square wave voltammetry (SWV) are used to investigate the suitability of CHP at the surface of MWCNTPE as a mediator for the electrocatalytic oxidation of Hcy in aqueous solutions. The kinetic parameters of the system, including electron transfer coefficient, and catalytic rate constant were also determined using the electrochemical approaches. In addition, SWV was used for quantitative analysis. SWV showed wide linear dynamic range (0.1–210.0 μM Hcy) with a detection limit of 0.08 μM Hcy. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of Hcy in real samples

Aerosol-assisted fabrication of mesoporous titania spheres with crystallized anatase structures and investigation of their photocatalitic properties

We demonstrate practical aerosol-assisted approach to synthesize spherical mesoporous titania particles with high surface areas. Scanning electron microscopy observation of the spray-dried products clearly shows spherical morphology. To remove surfactants and enhance crystallinity, the spray-dried products are calcined under various temperatures. The crystalline structures inside the particles are carefully detected by wide-angle XRD measurements. With increase of the calcination temperatures, anatase crystal growth proceeds and transformation from anatase to rutile is occurred. The effect of various calcination temperatures on the mesostructures is also studied by using N(2) adsorption desorption isotherms. The mesoporous titania particles calcined at 350, 400, and 500 A degrees C exhibit type IV isotherms with a capillary condensation step and shows a hysteresis loop, which is a characteristic of mesoporous materials. The reduction in the surface areas and the pore volumes is confirmed by increasing the calcination temperatures, while the average pore diameters are increased gradually. This is attributed to the distortion of the mesostructures due to the grain growth of the anatase phase and the transformation to the rutile phase during the calcination process. As a preliminary experimental photocatalytic activity, oxidative decomposition of acetaldehyde under UV irradiation is examined. The mesoporous titania calcined at 400 A degrees C shows the highest photocatalytic activity, due to both high surface area and well-developed anatase crystalline phase

Cerium-doped mesoporous TiO2 thin films: controlled crystallization of anatase with retention of highly ordered mesostructure

Here we report preparation of highly ordered mesoporous Ce-doped titania thin films by spin-coating method using surfactant-based precursor solutions. Various mesoporous titania films with different amounts of Ce content are prepared by changing the compositional ratios of Ti and Ce species in the precursor solutions. We carefully investigate the effect of the doped Ce amounts on "mesostructural ordering", "thermal stability", and "anatase crystallinity in the framework", respectively. By optimization of the doped Ce amounts, we demonstrate the successful anatase crystallization in the framework without any collapses of the ordered mesostructures

Effect of the mechanical activation on size reduction of crystalline acetaminophen drug particles

The decrease in particle size may offer new properties to drugs. In this study, we investigated the size reduction influence of the acetaminophen (C8H9O2N) particles by mechanical activation using a dry ball mill. The activated samples with the average size of 1 µm were then investigated in different time periods with the infrared (IR), inductively coupled plasma (ICP), atomic force microscopy (AFM), and X-ray diffraction (XRD) methods. The results of the IR and XRD images showed no change in the drug structure after the mechanical activation of all samples. With the peak height at full width at half maximum from XRD and the Scherrer equation, the size of the activated crystallite samples illustrated that the AFM images were in sound agreement with the Scherrer equation. According to the peaks of the AFM images, the average size of the particles in 30 hours of activation was 24 nm with a normal particle distribution. The ICP analysis demonstrated the presence of tungsten carbide particle impurities after activation from the powder sample impacting with the ball and jar. The greatest reduction in size was after milling for 30 hours.Peer ReviewedPostprint (published version

Synthesis of ZnO@TiO2 nanoparticles and its application to construct an electrochemical sensor for determination of hydrazine

In the present research, ZnO@TiO2 nanoparticles (ZnO@TiO2 NPs) was synthesized by using a simple method and the results of infrared (IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX) confirmed their synthesis. Then, an electrochemical sensor based on screen printed graphite electrode (SPGE) modified with ZnO@TiO2 NPs was developed for voltammetric detection of hydrazine in water samples. The ZnO@TiO2 NPs modified SPGE demonstrates significant performance toward the hydrazine detection due to the synergistic effect between ZnO NPs and TiO2 NPs and it proved by the results from cyclic voltammetry (CV). Also, the observation of an oxidation peak without a reduction peak in the opposite scan direction indicated the irreversibility of the electrochemical oxidation of hydrazine on both the bare SPGE and the ZnO@TiO2/SPGE. Under optimized conditions (pH and differential pulse parameters), the voltammetric current response of hydrazine at the ZnO@TiO2/SPGE showed linear dependence on the concentration, ranging from 0.01 µM to 585.0 µM with a limit of detection (LOD) of 0.005 µM. In addition, the pertinency of the ZnO@TiO2/SPGE sensor for practical applications was investigated by quantification detection of hydrazine in water samples. The findings showed recovery values between 97.3 % and 104.2 % and relative standard deviations (RSDs) ≤ 3.5 % for river and tap water samples

Synthesis and characterization of highly ordered titania-alumina mixed oxide mesoporous films with high alumina content

Highly ordered mesoporous Mania-alumina mixed oxide thin films are synthesized by using spin-coating method based on solvent evaporation process The mole ratios of doped alumina are controlled in the range from 0 to 30 mol% In order to achieve a highly ordered mesostructure, a low-temperature and low-humidity aging condition after the spin-coating is applied by means of controlling the hydrolysis and condensation reactions of metal species. During thermal treatment, the 1m-3m mesostructure is unidirectionally contracted along the direction perpendicular to the substrates The mesochannel walls are composed of periodically arranged cages with connecting necks between the neighboring cages. On the top-surface of the films, the uniformly-sized mesopores are observable. By doping alumina species in the pore walls, the thermal stability of the films is enhanced up to 450 degrees C. By finely tuning the amount of the doped alumina species, we can realize the successful anatase crystallization in the frameworks with the retention of the ordered mesoporous structures. The obtained mesoporous Mania-alumina mixed oxide films are fully characterized by 2D-grazing-incidence small-angle X-ray scattering (2D-GISAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Raman spectroscopy. (C) 2010 Elsevier Inc. All rights reserve