Synthesis and characterization of novel fluorine‐containing methacrylate copolymers: Reactivity ratios,thermal properties,and antimicrobial activity

The free‐radical‐initiated copolymerization of 2‐(4‐acetylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (AOEMA) and 2‐(4‐benzoylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (BOEMA) with 2‐[(4‐fluorophenyoxy]‐2‐oxoethyl‐2‐methylacrylate (FPEMA) were carried out in 1,4‐dioxane solution at 65°C using 2,2′‐azobisisobutyronitrile as an initiator with different monomer‐to‐monomer ratios in the feed. The monomers and copolymers were characterized by FTIR and ¹H‐ and ¹³C‐NMR spectral studies. ¹H‐NMR analysis was used to determine the molar fractions of AOEMA, BOEMA, and FPEMA in the copolymers. The reactivity ratios of the monomers were determined by the application of Fineman‐Ross and Kelen‐Tudos methods. The analysis of reactivity ratios revealed that BOEMA and AOEMA are less reactive than FPEMA, and copolymers formed are statistically in nature. The molecular weights (M _w and M _n) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of FPEMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of FPEMA in the copolymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Possibility of producing lightweight,heat insulating bricks from pumice and H3PO4- or NH4NO3-hardened molasses binder

This investigation is based on the production of lightweight, heat-insulating, water-resistant or water-repellent materials from lightweight aggregates, such as pumice and/or expanded perlite, without using cement or plaster as a binder. The results of this investigation reveal that a H₃PO₄- or NH₄NO₃-hardened molasses binder with the addition of 2.5% borax could be an alternative binder for the production of lightweight, heat-insulating materials with moderate tensile strength. When these bricks were exposed to temperatures up to 825 °C, they did not lose their strength but, rather gained strength. Therefore, molasses binder could be an alternative to cement or plaster binder for construction and building materials with specific properties.     

Influences of sex and seasons on levels of heavy metals in tissues of green tiger shrimp (Penaeus semisulcatus de Hann, 1844)

Seasonal changes in heavy metal (Ag, Cr, Ni, Pb, Cu, Fe, Zn) concentrations in muscle, gill, hepatopancreas and gonad tissues of both male and female green tiger shrimp (Penaeus semisulcatus) from Iskenderun Bay (Northern East Mediterranean Sea, Turkey) were measured for a year period by using ICP-AES. The relationships in various heavy metal concentrations in organs were compared according to sex and seasons. Heavy metal content varied with type of metals, seasons and sex. Accumulations also differed significantly in certain organs. Metal concentrations (as μg g⁻¹ w.w.) were highest in male gonads whereas lowest in the muscle of all shrimp species. From the human consumption point of view, heavy metal concentrations except for copper in male and female green tiger shrimp’s muscle were below the admissible limits. Thus, precautions should be taken on account of higher content of heavy metals as well as in other organs that could be affected by industrial pollution.     

Patent analysis of wind energy technology using the patent alert system

Using publicly available information effectively is important to remain competitive in technology related industries. The main difficulty in this is determining how to use the information effectively and in a manner that will yield results that can be acted upon. Several different methodologies are being developed in the Technology Watch area of research including the Patent Alert System (PAS) by Dereli and Durmusoglu. By using two different variations of the Patent Alert System, this paper will analyze two different technologies based on wind energy. These variations include Linear Regression based PAS and Fuzzy Logic based PAS. Each approach uses a different methodology to evaluate the available data and generate a trend that will be used to predict future values of patent counts in the applied area of technology. The results of these different approaches are compared in order to determine if either method produces more reliable results which would then lead to better decisions by the organization. In order to connect the results with real-world events, trend changes will be evaluated against global events which should have an impact on technological development in this area.     

A novel Central Composite Design based response surface methodology optimization study for the synthesis of Pd/CNT direct formic acid fuel cell anode catalyst

At present, carbon nanotube supported Pd catalysts are synthesized via NaBH₄ reduction method to investigate their electro catalytic activity thorough formic acid electro oxidation. In order to optimize the synthesis conditions such as %Pd amount (X₁), NaBH₄ amount (times, X₂), water amount (ml, X₃), and time (min., X₄), Central Composite Design (CCD) experiments are designed and determined by the Design-Expert program to determine the maximum observed current (mA/mgPd). Formic acid electro oxidation current density of the catalyst is computed by the model as 974.80 mA/mg Pd for the catalyst prepared at optimum operating conditions (41.14 for %Pd amount, 280.23 NaBH₄ amount, 26.80 ml water amount, and 167.14 min time) obtained with numerical optimization method in CCD. This computed value is very close to the experimentally measured value as 920 mA/mg Pd. Finally, formic acid fuel cell measurements were performed on the Pd/CNT catalyst prepared at optimum operating conditions and compared with the commercial Pd black and Pt black catalysts. As a result, Pd/CNT exhibits better performance compared to Pd black, revealing that Pd/CNT is a promising catalyst for the direct formic acid fuel cell measurements.     

Hydrogen production via propane dry reforming: Carbon deposition and reaction-deactivation study

Carbon deposition during carbon dioxide reforming reaction of C₃H₈ has been studied over alumina-supported bimetallic Mo/CoNi catalysts. To better understand the carbon-induced deactivation during the reforming reaction, changes in catalyst morphology and carbon deposition kinetics were examined. Different characterization techniques were used for both fresh and rejuvenated catalysts including liquid nitrogen adsorption/desorption, chemisorption via hydrogen, ammonia and CO₂ desorption, and thermogravimetric measurement of the coked catalysts. The time dependant reaction rate profiles indicated that MoNi catalyst has higher syngas (H₂/CO) formation rates with lower CO₂ rate of consumption compared to CoNi catalyst. However, the H₂:CO ratio values were almost the same for both catalysts suggesting similarity in the product formation pathway. Conversion-time analysis showed that MoNi catalyst was more stable and active during a 72-h run while CoNi suffered noticeable deactivation after 30 h on-stream. Reaction-deactivation models implicated a higher deactivation coefficient (k_d) with activation energy of E_d = 78.1 kJ mol^?1 for the cobalt-containing Ni catalyst, while the Ni catalyst with molybdenum had a lower deactivation coefficient with smaller activation energy of just under 70 kJ mol^?1. Post-mortem analysis (TPR-TPO dual cycle and TOC) of spent catalysts confirmed that the surface of CoNi catalyst has more carbon residue than the MoNi sample which was consistent with the higher deactivation of CoNi.     

Effects of diameter ratio of adiabatic circular cylinder and tilt angle on natural convection from a square open tilted cavity

A numerical analysis is carried out to study the performance of natural convection inside a square open tilted cavity filled with air. An adiabatic circular solid cylinder is placed at the center of the cavity and the sidewall in front of the breathing space is heated by a constant heat flux. The top and bottom walls are kept at the ambient constant temperature. Two‐dimensional forms of Navier–Stokes equations along with the energy equations are solved using the Galerkin finite element method. Results are obtained for a range of Grashof numbers from 10³ to 10⁶ at Pr = 0.71 while the tilt angle varies from 0 to 45° and the diameter ratio of the cylinder is considered to be 0.2, 0.3, and 0.4 with constant physical properties. The parametric studies for a wide range of cylinder diameter ratios and cavity tilt angles show significant features of the present problem in terms of stream functions and temperature profiles. The computational results indicate that the heat transfer coefficient is strongly influenced by the above governing parameters. It is also found that the average Nusselt number decreases when the diameter ratio increases. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21001     

MHD natural convection inside an inclined trapezoidal porous enclosure with internal heat generation or absorption subjected to isoflux heating

A steady laminar two‐dimensional magneto‐hydrodynamic natural convection flow in an inclined trapezoidal enclosure filled with a fluid‐saturated porous medium is investigated numerically using a finite difference method. The left and right vertical sidewalls of the trapezoidal enclosure are maintained at a cold temperature. The horizontal top wall is considered adiabatic while the bottom wall is subjected to isoflux heating. A volumetric internal heat generation or absorption is embedded inside the trapezoidal enclosure while an external magnetic field is applied on the left sidewall of the enclosure. In the current work, the following parametric ranges of the non‐dimensional groups are used: Hartmann number is varied as , Darcy number is taken as , 10^?4, and 8 × 10^?5, Rayleigh number is varied as , Prandtl number is considered constant at Pr = 0.7, the dimensionless internal heat generation or absorption parameter is varied as Δ = ?0.2, 0, 1, and 2.0, while the trapezoidal enclosure inclination angle is varied as . The results indicated a strong flow circulation occurs when the Darcy and the Rayleigh numbers are high. In addition, it is found that the Hartmann number, internal heat generation or absorption parameter and inclination angle have an important role on the flow and thermal characteristics. It is also found that when the enclosure inclination angle and Hartmann number increase the average Nusselt number along the hot bottom wall decreases. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21013     

Viscous dissipation effects on thermal transport characteristics of combined pressure and electroosmotically driven flow in microchannels

This study investigates the influence of viscous dissipation on thermal transport characteristics of the fully developed combined pressure and electroosmotically driven flow in parallel plate microchannels subject to uniform wall heat flux. Closed form expressions are obtained for the transverse distributions of electrical potential, velocity and temperature and also for Nusselt number. From the results it is realized that the Brinkman number has a significant effect on Nusselt number. Generally speaking, to increase Brinkman number is to decrease Nusselt number. Although the magnitude of Joule heating can affect Brinkman number dependency of Nusselt number, however the general trend remains unchanged. Depending on the value of flow parameters, a singularity may occur in Nusselt number values even in the absence of viscous heating, especially at great values of dimensionless Joule heating term. For a given value of Brinkman number, as dimensionless Debye–Huckel parameter increases, the effect of viscous heating increases. In this condition, as dimensionless Debye–Huckel parameter goes to infinity, the Nusselt number approaches zero, regardless of the magnitude of Joule heating. Furthermore, it is realized that the effect of Brinkman number on Nusselt number for pressure opposed flow is more notable than purely electroosmotic flow, while the opposite is true for pressure assisted flow.