Nonionic surfactant-templated mesoporous carbon as an electrocatalyst support for methanol oxidation

Two carbons were synthesized for use as platinum electrocatalyst supports for methanol oxidation. For both materials, furfuryl alcohol was used as the carbon precursor; however, one (CPEG) was made using poly ethylene glycol as the pore former, while the other (CSRF) was produced using Pluronic^® F127 as the soft template by organic–organic self-assembly. The CPEG and CSRF carbons were estimated from nitrogen physisorption experiments to be micro- and mesoporous, respectively. Platinum nanoparticles were deposited on each carbon as well as on Vulcan XC-72 carbon by the formic acid reduction method. The physicochemical properties of electrocatalysts were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX), and their electrochemical features were examined using cyclic voltammetry, chronoamperometry, and impedance spectroscopy. It was found that higher methanol oxidation peak current densities as well as lesser charge transfer resistance at electrode/electrolyte interface were obtained for Pt supported on CSRF as compared to those on Vulcan XC-72 carbon, owing to the higher specific surface area and larger total pore volume (696 m² g⁻¹ and 0.60 cm³ g⁻¹, respectively) together with superior electrical conductivity of mesoporous CSRF. On the other hand, the lower surface area and pore volume of microporous CPEG substrate confined Pt nanoparticles deposition and thus made CPEG-supported Pt an inefficient methanol oxidation electrocatalyst.     

A survey on automated detection and classification of acute leukemia and WBCs in microscopic blood cells

Multimedia Tools and Applications - Leukemia (blood cancer) is an unusual spread of White Blood Cells or Leukocytes (WBCs) in the bone marrow and blood. Pathologists can diagnose leukemia by...     

Ready-time partitioning algorithm for computation offloading of workflow applications in mobile cloud computing

The Journal of Supercomputing - To augment the capabilities of mobile devices, application partitioning solutions in mobile cloud computing have emerged to decide the execution location of each...     

Physicochemical and Enzymatic Properties of Five Kiwifruit Cultivars during Cold Storage

Samples of Abbot, Alison, Bruno, Monty, and Hayward cultivars of kiwifruit (Actinidia deliciosa) were obtained from the Iran Research Center of Citrus (Tonekabon, located in north of Iran) and their physicochemical properties were studied during cold storage (at T = 1 ± 1 °C, RH = 80 ± 5%) at 0-, 9-, and 18-week intervals. The mean chemical composition of the fruits were as follows: ash = 0.66–0.96%, moisture = 75.2–84.7%, starch = 0.3–7.0%, and ascorbic acid = 54.8–261.0; K = 125.0–372.0 mg 100 g⁻¹ fresh weight, Mg = 18.0–32.0 mg 100 g⁻¹ fresh weight, Na = 1.4–3.1 mg 100 g⁻¹ fresh weight, Fe = 0.17–0.52 mg 100 g⁻¹ fresh weight, Cu = 0.04–0.24 mg 100 g⁻¹ fresh weight, Zn = 0.16–0.49 mg 100 g⁻¹ fresh weight, Mn = 0.04–0.10 mg 100 g⁻¹ fresh weight, and P = 25.2–49.3 mg 100 g⁻¹ fresh weight; glucose = 0.7–2.39%, fructose = 1.20–3.13%, and sucrose = 0.0–5.8%. At the same time, the values of the parameters °Brix = 6.5–14.8% and acidity = 1.8–2.5% of the studied cultivars (mutual effects of cultivar and storage time) were investigated. The increase in peroxidase (POX = 0.0–6.65 U ml⁻¹) and the decrease in pectinesterase (PE; poor activity to 0) activities were also determined. The statistical analysis showed that the Bruno cultivar had the highest content of ascorbic acid (115.0–261.0 mg 100 g⁻¹ fresh weight), which is an important compound in fruits during storage, while Hayward had the best overall quality particularly with regards to its resistance to softening. This study confirms that long-term cold storage at 1 ± 1 °C and 80 ± 5% RH is suitable for maintaining the highest quality of Iranian grown cultivars of kiwifruit.     

Modified multistep electrophoretic deposition of TiO2 nanoparticles to prepare high quality thin films for dye-sensitized solar cell

In this study, a modified procedure is introduced which consists of multistep process for improving the structure of mesoporous TiO₂ films. The films were prepared by electrophoretic deposition (EPD) on FTO (F-SnO₂ coated glass). It is shown that high quality TiO₂ film can be produced by multistep EPD method. The effect of EPD time on the thickness and density of the films have been investigated. The performance of dye-sensitized solar cells (DSSCs) that were fabricated by improved layer are tested under AM 1.5 simulated sunlight. Finally, the structure and effective parameters of DSSCs that were fabricated by one step and multistep EPD are investigated precisely, using electrochemical impedance spectroscopy.     

Taguchi optimization approach for Pb(II) and Hg(II) removal from aqueous solutions using modified mesoporous carbon

Using the Taguchi method, this study presents a systematic optimization approach for removal of lead (Pb) and mercury (Hg) by a nanostructure, zinc oxide-modified mesoporous carbon CMK-3 denoted as Zn-OCMK-3. CMK-3 was synthesized by using SBA-15 and then oxidized by nitric acid. The zinc oxide was loaded to the modified CMK-3 by the equilibrium adsorption of Zn(II) ions from aqueous solution followed by calcination to convert zinc nitrate to zinc oxide. The CMK-3 had porous structure and high specific surface area which can accommodate zinc oxide in a spreading manner, the zinc oxide connects to the carbon surface via oxygen atoms. The controllable factors such as agitation time, initial concentration, temperature, dose and pH of solution have been optimized. Under optimum conditions, the pollutant removal efficiency (PRE) was 97.25% for Pb(II) and 99% for Hg(II). The percentage contribution of each controllable factor was also determined. The initial concentration of pollutant is the most influential factor, and its value of percentage contribution is up to 31% and 43% for Pb and Hg, respectively. Our results show that the Zn-OCMK-3 is an effective nanoadsorbent for lead and mercury pollution remediation. Langmuir and Freundlich adsorption isotherms were used to model the equilibrium adsorption data for Pb(II) and Hg(II).     

A Fully Integrated MIMO Multiband Direct Conversion CMOS Transceiver for WLAN Applications (802.11n)

802.11n is the latest offering from the IEEE standard committee tasked with enabling and enhancing WLAN systems. This standard utilizes several techniques to offer a much larger rate versus range than the legacy WLAN systems. A single-chip multiband direct-conversion CMOS MIMO transceiver (2times2) targeted for WLAN applications is presented. This transceiver is capable of satisfying the requirements of the draft 802.1 In standard and achieves PHY rates of > 270 Mb/s. The receivers and transmitters achieve an EVM of better than -41 dB (0.9%) and -40 dB (1.0%) operating in legacy g and a modes, respectively. From a 1.8 V supply and with both cores operating, the chip draws 275 mA in RX mode and 280 mA in TX mode.     

Comparative study of simulated annealing,genetic algorithms and tabu search for solving binary and comprehensive machine-grouping problems

Machine/part grouping problems have proven to be NP-complete and cannot be solved in polynomial time. Solving such problems of reasonable size often relies on heuristic approaches. Recently, several metaheuristic approaches have emerged as efficient tools for solving such problems. However, the development and implementation of such meta-heuristics have not been a trivial issue. The merits of each method and the problems involved in implementation may not be easily apprehended by practitioners, thereby posing difficulties in the selection of an efficient heuristic for industrial applications. For this reason, a comparative study of three important metaheuristic approaches--simulated annealing, genetic algorithms and tabu search for both binary (considering only machines and part types) and comprehensive (involving machine/part types, processing times, lot sizes, and machine capacities) machine grouping problems--was carried out. To test the performance of the three metaheuristics, two binary performance indices and two generalized performance indices were respectively used for binary and comprehensive machine/part grouping problems. The comparisons were made in terms of solution quality, search convergence behaviour and presearch effort. The results indicate that simulated annealing outperforms both genetic algorithm and tabu search particularly for large problems. The genetic algorithm seems slightly better than the tabu search method for the comprehensive grouping problems.     

A new simplified model for evaluating non-uniform thermal sensation caused by wearing clothing

In the standard thermal sensation models such as Fanger's and Gagge's models, the clothing system is simulated as an overall insulation covering the whole body. But under actual conditions, some segments of body are bare and other parts are covered by clothing. In addition, there is a significant difference between thermal sensation of the bare and that of covered segments. Moreover, to use a more complex multi-segmented model, large amount of empirical data is required to simulate each segment of the body. The data, then, must be numerically analyzed to determine the thermal parameters for each segment and its subdivided layers. In this study, a simplified three-node and easy-to-implement thermal sensation model is presented based on Gagge's standard model. In the present model the human body is subdivided into three lumped compartments: core, bare skin, and clothed skin. Thermoregulatory parameters of each compartment are determined by the relative energy balance equation of the compartment. The present model accurately estimates the thermal sensation of the bare as well as the clothed parts of the body. The model has been verified against the analytical and experimental results where a good agreement was found.     

Framework for network survivability performance

The article is based on the results of ANSI Technical Subcommittee T1A1 activities in the area of a general framework for telecommunication network survivability performance. The issues of users' expectations and requirements, outage categorization, and a framework for analysis of survivability techniques are discussed. Based on the survivability framework, models for network survivability assessment and analysis are considered, and performance measures are described. Examples illustrate the application of this framework in network design and planning