Calculation of reactivity ratios of methacrylic acid-ethyl acrylate copolymer by on-line quantitative 1H NMR spectroscopy

The solution copolymerization of methacrylic acid (MAA) and ethyl acrylate (EA) was studied by online proton nuclear magnetic resonance spectroscopy (¹H NMR) using 2,2′–azobisisobutyronitrile as an initiator in deuterated dimethyl sulfoxide at 60 °C. The chemical compositions of the copolymer and the comonomer concentrations were determined from the conversion of comonomers to copolymer by quantitative in situ NMR monitoring to estimate the reactivity ratios of the comonomers at low conversion. This is a new and easy methodology to analyze radical copolymerization. In this research, it is shown that monomer reactivity ratios can be calculated by data collected only from one initial comonomer mixture composition via online monitoring progress of the copolymerization reaction. The reactivity ratios of MAA and EA are equal to 2.360 and 0.414, respectively. This approach is used to compute the monomer reactivity ratios in a nonlinear integrated form of the copolymerization equation which is described by Mayo and Lewis terminal model. The fairly good agreement between the results and the literature data reported for the emulsion system represent the accuracy of the reactivity ratios calculated by this new approach. The calculated reactivity ratios for emulsion copolymerization are r _MAA = 2.040 and r _EA = 0.470, and the previous literature data are r _MAA = 2.580 and r _EA = 0.157.     

Application of Ozone Post-Harvest Treatment on Kabkab Date Fruits: Effect on Mortality Rate of Indian Meal Moth and Nutrition Components

Methyl bromide (MB) was used for years to treat infested stored date fruits; however, MB is due to be phased out by 2015. In this study ozone is used for disinfestations of Kabkab date against Indian meal moth in three life stage. They were exposed to four ozone concentrations (300 ± 10, 1050 ± 40, 2000 ± 40, and 4000 ± 50 ppm) during four periods (2, 4, 6, and 8 h). The findings show 2000 ppm of ozone concentration within 8 h resulted in complete mortality of larvae and adult insects and over 90% mortality of eggs. The proposed ozone treatment is a promising approach replacing application of MB for disinfestations of examined date fruits, as no remarkable changes were observed on pH of the date fruits and its chemical compositions (total phenolic content, anti-oxidant activity and free radicals).     

Enhancing fractal image compression speed using local features for reducing search space

The encoding step in full-search fractal image compression is time intensive because a sequential search through a massive domain pool has to be executed to find the best-matched domain for every range block. To afford a fair encoding time, immaterial domain–range block comparisons should be prevented. In this paper, a new local binary feature resemble to local binary patterns method is introduced. This single local feature is robust to noise and can exploit the general structure of the block. Concerning similarity between range–domain blocks, a criterion is allocated dynamically by measuring the pixel diversity among the range block pixels. To avoid redundant calculations, the distance of the general pattern is assessed by the Hamming distance utilizing a pre-computed table. Experimental results show that the presented approach can make FIC a lot faster as opposed to the full-search method and outperform some other identical methods while preserving the quality of the decoded images. Indeed, the proposed method can be utilized inside identical applications that want a specific block size or blocks comparing.     

Influence of Pore Characteristics on Electrochemical and Biological Behavior of Ti Foams

This study reports on titanium (Ti) foams produced using the powder metallurgy technique. During the investigation, the cross-sectional area and perimeter distributions of the pores within the foam were measured. Metallographic image processing analysis software combined with scanning electron microscopic images demonstrated that the pore size and circularity were affected by varying the volume percentage of the space-holder material. The corrosion resistance was investigated using electrochemical impedance spectroscopy and cyclic polarization tests. MG-63 osteoblast-like cells were used to study the biocompatibility and to evaluate the cell attachment, viability, and alkaline phosphatase activity. Analytical results indicated that 50 and 60 vol.% samples were suitable for biomedical applications. Because of the high degree of interconnectivity in the 60 and 70% porosity samples, the electrochemical parameters produced similar results. The corrosion rate of the porous samples showed that the amount of dissolved Ti was at an acceptable level that can be ejected by the body. Applying a fluoridated hydroxyapatite coating significantly increased the osteoblast cell functions on the porous surface.     

Fabrication and in vitro degradation study of novel optically active polymers derived from amino acid containing diacids and 4,4′-thiobis(2-tert-butyl-5-methylphenol)

Chiral bioactive poly(ester-imide)s (PEI)s were synthesized from N,N′-(pyromellitoyl)-bis-(L-phenylalanine) and N,N′-(pyromellitoyl)-bis-(L-leucine) diacids derived from amino acids with 4,4′-thiobis(2-tert-butyl-5-methylphenol) via direct polycondensation reaction in a system of tosyl chloride, pyridine and N,N-dimethylformamide as a condensing agent. The structures of these polymers were confirmed by FT-IR, ¹H-NMR, specific rotation, elemental and thermogravimetric analysis (TGA) techniques. TGA showed that the 10% weight loss temperature in a nitrogen atmosphere was more than 390 °C, which indicates that the resulting PEIs have a good thermal stability. The biodegradability of the monomers and prepared polymers was investigated in culture media and soil burial test for assessing the susceptibility of these compounds to microbial degradation. The results showed that the synthesized monomers and theirs derived polymers are biologically active and they are nontoxic to microbial growth.     

Cellulose-graft-polyacrylamide/hydroxyapatite composite hydrogel with possible application in removal of Cu (II) ions

Cellulose-graft-polyacrylamide/hydroxyapatite composite hydrogels of different weight ratios were prepared through a suspension polymerization method. Physical and chemical characteristics of the composite were investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling behaviors of the composite hydrogels were investigated under varying conditions of time, temperature and pH. The optimized swelling capacity in standard conditions was found to be 5197% per gram of the hydrogel. The prepared hydrogel has the potential to be used for ion adsorption in water treatment. Such a possibility was examined through adsorption of copper (II) ions from an aqueous solution. The effects on adsorption of varying the time, pH, and initial concentration of copper (II) solution as well as some thermodynamic parameters were also investigated. The maximum adsorption capacity was found to be 175 mg per gram of composite hydrogel in dried state. The mechanism of adsorption was well presented using a pseudo-second-order kinetic model. Finally, the mercury-loaded hydrogel was regenerated without losing its original activity and stability.     

Synthesis and characterization of novel poly(amide-ether)s bearing imidazole pendants: study of physical and optical properties

Two new para-linked diether-diamines, bis(4-(4-amino-2-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy) phenyl)methanone and bis(4-(4-amino-2-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy) phenyl)hexafluoropropane, bearing two ortho-linked phenyl-substituted imidazole pendants and trifluoromethyl groups were synthesized by the nucleophilic chlorodisplacement reaction of the synthesized 2-(2-chloro-5-nitrophenyl)-4,5-diphenyl-1H-imidazole with 4,4′-dihydroxybenzophenone or 4,4′-(hexafluoroisopropylidene)diphenol in refluxing DMAc in the presence of potassium carbonate. These diamines were utilized to prepare a series of novel poly(amide-ether)s (PAEs) via direct phosphorylation polycondensation with aliphatic and aromatic dicarboxylic acids. The polymeric samples were readily soluble in a variety of organic solvents and formed low-colored and flexible thin films via solution casting. These polymers showed glass-transition temperatures (T _gs) between 204 and 308 °C. Thermal behaviors of the PAEs were characterized by thermogravimetric analysis, and the 10 % weight loss temperatures were found to be in the range of 330–450 °C in N₂. The PAEs exhibited fluorescence emission in solution and in solid state with maxima around 423–494 nm and with the quantum yields in the range of 6–28 %.     

The effects of visualization and interaction techniques on feature model configuration

A Software Product Line is a set of software systems of a domain, which share some common features but also have significant variability. A feature model is a variability modeling artifact which represents differences among software products with respect to variability relationships among their features. Having a feature model along with a reference model developed in the domain engineering lifecycle, a concrete product of the family is derived by selecting features in the feature model (referred to as the configuration process) and by instantiating the reference model. However, feature model configuration can be a cumbersome task because: 1) feature models may consist of a large number of features, which are hard to comprehend and maintain; and 2) many factors including technical limitations, implementation costs, stakeholders’ requirements and expectations must be considered in the configuration process. Recognizing these issues, a significant amount of research efforts has been dedicated to different aspects of feature model configuration such as automating the configuration process. Several approaches have been proposed to alleviate the feature model configuration challenges through applying visualization and interaction techniques. However, there have been limited empirical insights available into the impact of visualization and interaction techniques on the feature model configuration process. In this paper, we present a set of visualization and interaction interventions for representing and configuring feature models, which are then empirically validated to measure the impact of the proposed interventions. An empirical study was conducted by following the principles of control experiments in software engineering and by applying the well-known software quality standard ISO 9126 to operationalize the variables investigated in the experiment. The results of the empirical study revealed that the employed visualization and interaction interventions significantly improved completion time of comprehension and changing of the feature model configuration. Additionally, according to results, the proposed interventions are easy-to-use and easy-to-learn for the participants.     

Optimal pricing model for electronic products

Electronic commerce encompasses all electronically conducted business activities, operations, and transaction processing. With the development of electronic commerce via Internet, during the past decade, many companies have changed the way they connect to and deal with their customers and partners. In this paper we introduce a Geometric Programming (GP) based model to analyze the pricing method and the service quality for E-business companies. The proposed method of this paper considers electronic products which are all kinds of products to be sold via web supermarkets. Therefore, they can cover pure digital and also non-digital products. The model proposed in this research work, deals with non-digital goods, which are supplied through web. The resulted non-linear model is directly solved by using Geometric Programming (GP) and a closed form of solution is presented. We assume that the demand is influenced by price, marketing and service expenditures. We also assume that the cost of production is affected by demand. We analyze the solution in different cases, in order to study the behavior of the model and for each case numerical examples are used to demonstrate the implementation of our analysis. The sensitivity analysis is also presented at the end to analyze the behavior of the model.     

A dual-mode tunable bandpass filter for GSM,UMTS, WiFi,and WiMAX standards applications

This paper presents a dual-mode tunable bandpass filter (BPF) for global system for mobile communication, universal mobile telecommunications system, wireless fidelity, and worldwide interoperability for microwave access standard applications. The proposed filter consists of a stepped-impedance resonator, single resonator, and coupled line, which are loaded with varactors. The center frequency and bandwidth of the proposed filter can be tuned with tuning varactors. Furthermore, the measurement results show that the BPF can be tuned over the frequency range of 1.8 to 2.5 GHz. Moreover, the bandwidth can be changed at each certain frequency. Furthermore, using PIN diodes, a bandstop filter is added to the tunable BPF to reduce the out-of-band frequencies around the desired frequencies. The values of LC equivalent circuits are calculated, and the results are compared with those obtained from the layout of the proposed structure. Finally, the measurement results justify the simulation results.