Effect of electric field on isomer ratio formed during the mononitration of toluene

The distribution of isomers in mononitration of toluene is demonstrated to be dependent upon the properties of the solvents involved. An empirical model has been derived to relate the isomer ratio with the dipole moments and dielectric constants of the solvents. Based on this observation, an investigation into the effect of electric field on the distribution of isomers in continuous mononitration of toluene has been carried out.     

Some aspects of homogeneous and two-phase aromatic sulphonation

The two-phase sulphonation of benzene and toluene with concentrated sulphuric acid solutions at 30°C has been studied in a continuous stirred tank reactor (1.06 dm³ capacity). The rates of reaction, as a function of sulphuric acid concentration and the overall mass transfer coefficient times, and the interfacial area per unit volume of the acid phase as a function of agitation speed, have been determined. In homogeneous systems, the kinetic rate constants and the relative rates of sulphonation of a series of aromatic hydrocarbons have been measured in the range of 13–16 mol dm^?3 sulphuric acid. It has been shown that the rates of sulphonation of compounds, with levels of reactivity beyond that of m-xylene, are likely to be affected by diffusional phenomena.     

Sustained oscillations in MIMO nonlinear systems through limit cycle shaping

This paper studies on generating periodic behaviors through shaping stable limit cycles in multiple‐input‐multiple‐output nonlinear systems. For this purpose, first, limit cycles are shaped with respect to the desired sustained oscillations of the system's outputs. Then, the Lyapunov analyses, which are appropriate for stability analysis of invariant sets, are employed to design the control law and conclude the asymptotic convergence toward the predefined limit cycles. The problem is studied in two cases. In the first case, some assumptions in the mathematical model are assumed that leads to simplification in the design procedure. In the second case, the design procedure is discussed in more general cases. Finally, the validity and performance of the proposed method for shaping limit cycles with different geometric shapes are illustrated by computer simulations for practical and numerical examples.     

Static and Cyclic Load-Deflection Characteristics of NiTi Orthodontic Archwires Using Modified Bending Tests

Near-equiatomic nickel-titanium (nitinol) has the ability to return to a former shape when subjected to an appropriate thermomechanical procedure. One of the most successful applications of nitinol is orthodontic archwire. One of the suitable characteristics of these wires is superelasticity, a phenomenon that allows better-tolerated loading conditions during clinical therapy. Superelastic nitinol wires deliver clinically desired light continuous force enabling effective tooth movement with minimal damage for periodontal tissues. In this research, a special three-point bending fixture was invented and designed to determine the superelastic property in simulated clinical conditions, where the wire samples were held in the fixture similar to an oral cavity. In this experimental study, the load-deflection characteristics of superelastic NiTi commercial wires were studied through three-point bending test. The superelastic behavior was investigated by focusing on bending time, temperature, and number of cycles which affects the energy dissipating capacity. Experimental results show that the NiTi archwires are well suited for cyclic load-unload dental applications. Results show reduction in superelastic property for used archwires after long-time static bending.     

Glucose affects monocarboxylate cotransporter (MCT) 1 expression during mouse preimplantation development

Cleavage-stage embryos have an absolute requirement for pyruvate and lactate, but as the morula compacts, it switches to glucose as the preferred energy source to fuel glycolysis. Substrates such as glucose, amino acids, and lactate are moved into and out of cells by facilitated diffusion. In the case of lactate and pyruvate, this occurs via H+-monocarboxylate cotransporter (MCT) proteins. To clarify the role of MCT in development, transport characteristics for DL-lactate were examined, as were mRNA expression and protein localisation for MCT1 and MCT3, using confocal laser scanning immunofluorescence in freshly collected and cultured embryos. Blastocysts demonstrated significantly higher affinity for DL-lactate than zygotes (Km 20 +/- 10 vs 87 +/- 35 mmol lactate/l; P = 0.03 by linear regression) but was similar for all stages. For embryos derived in vivo and those cultured with glucose, MCT1 mRNA was present throughout preimplantation development, protein immunoreactivity appearing diffuse throughout the cytoplasm with brightest intensity in the outer cortical region of blastomeres. In expanding blastocysts, MCT1 became more prominent in the cytoplasmic cortex of blastomeres, with brightest intensity in the polar trophectoderm. Without glucose, MCT1 mRNA was not expressed, and immunoreactivity dramatically reduced in intensity as morulae died. MCT3 mRNA and immunoreactivity were not detected in early embryos. The differential expression of MCT1 in the presence or absence of glucose demonstrates that it is important in the critical regulation of pH and monocarboxylate transport during preimplantation development, and implies a role for glucose in the control of MCT1, but not MCT3, expression.     

Multiple-scattering effects on static light-scattering optical structure factor measurements

We show that the extent and effect of multiple scattering on angularly resolved light-scattering intensity measurements, the optical structure factor, can be quantitatively described by a single parameter, the average number of scattering events along the scattering volume. This quantity is easily measured or calculated and hence provides a useful experimental indicator of multiple scattering, which is a hindrance to accurate structure factor measurements.     

Preparation a core-shell lipid/polymer nanoparticle containing Isotretinoin drug with pH sensitive property: A response surface methodology study

In this study, a core-shell lipid/polymer nanoparticle (NP) was prepared to deliver Isotretinoin drug with pH sensitive and controllable drug release property for oral administration usage. Chitosan was cross-linked to tripolyphosphate to form the core of the NP using the ionic gelation technique and coated with glycerol monostearate lipid as a shell by applying a two-step approach. Response surface methodology was used to investigate the effects of various parameters on particle size and drug entrapment efficiency of the nanoparticles. Optimal nanoparticles with lower particle size and higher entrapment efficiency had a diameter of 100 nm based on TEM analysis and 64% drug entrapment efficiency. Coating NPs surface with lipid changed the NPs charge, hydrophilicity and swelling property. Lipid coating NPs changed release rate from 6 to 4% after 2 h in simulated gastric fluid (SGF), 9 to 16% after 6 h in simulated intestine fluid (SIF) and 21 to 71% after 7 days in blood medium. Kinetic modeling of drug release confirmed Fickian diffusion based on Higuchi model in SIF and blood media where swelling and dissolution of polymer network were negligible, while drug dissolution due to polymer swelling in SGF media was the dominant mechanism for drug release.     

Power generation from organic substrate in batch and continuous flow microbial fuel cell operations

Microbial fuel cells (MFCs) are biochemical-catalyzed systems in which electricity is produced by oxidizing biodegradable organic matters in presence of either bacteria or enzyme. This system can serve as a device for generating clean energy and, also wastewater treatment unit. In this paper, production of bioelectricity in MFC in batch and continuous systems were investigated. A dual chambered air–cathode MFC was fabricated for this purpose. Graphite plates were used as electrodes and glucose as a substrate with initial concentration of 30 g l⁻¹ was used. Cubic MFC reactor was fabricated and inoculated with Saccharomyces cerevisiae PTCC 5269 as active biocatalyst. Neutral red with concentration of 200 μmol l⁻¹ was selected as electron shuttle in anaerobic anode chamber. In order to enhance the performance of MFC, potassium permanganate at 400 μmol l⁻¹ concentration as oxidizer was used. The performance of MFC was analyzed by the measurement of polarization curve and cyclic volatmmetric data as well. Closed circuit voltage was obtained using a 1 kΩ resistance. The voltage at steady-state condition was 440 mV and it was stable for the entire operation time. In a continuous system, the effect of hydraulic retention time (HRT) on performance of MFC was examined. The optimum HRT was found to be around 7 h. Maximum produced power and current density at optimum HRT were 1210 mA m⁻² and 283 mW m⁻², respectively.     

FUZZY FA: A MODIFIED FIREFLY ALGORITHM

The firefly algorithm (FA), which is usually used in optimization problems, is a stochastic, population-based algorithm inspired by the intelligent, collective behavior of fireflies in nature. In the standard FA, each firefly in each neighborhood is compared with other fireflies, and the less-bright firefly moves toward the brighter one (in the maximization optimization). In fact, in the standard FA, firefly movement is based on the local optima, and the global optima do not have any effect on the movement of fireflies. So, the exploration rate of the FA decreases. In this study, we propose a new, fuzzy-based, modified version of the standard FA—the fuzzy firefly algorithm (FFA)—to increase the exploration and improve the global search of the FA. In the FFA, to improve the speed of finding the global optima, in each iteration the global optima and some brighter fireflies have influence on the movement of fireflies. The effect of each firefly depends on its attractiveness, which is considered as a fuzzy variable in the FFA. In order to evaluate the proposed FFA, seven well-known benchmark functions, including Sphere, Rastrigin, Rosenbrock, Step, Schwefel's P2.22, Ackly, and the Xin-She Yang functions are used in 10-, 20-, and 30-dimensional spaces. Also, to indicate the effectiveness of the proposed FFA, we utilize our approach in a multilevel image-thresholding application, which is one of the most important and challenging issues in image segmentation, and we propose the FFA-Otsu method. The experimental results show that our proposed method can be effective to find the global optima and can improve the global search and the exploration rate of the standard FA. Moreover, the obtained thresholding results show that the proposed FFA-Otsu algorithm is more efficient when compared with other benchmark approaches for image segmentation.