Multi-component reaction synthesis of novel 3-phenyl-3,4-dihydro-2H-benzo[a][1,3] oxazino[5,6-c]phenazine derivatives catalyzed by reusable ZnO-PTA@Fe3O4/EN-MIL-101(Cr) nanopowder at room temperature

ABSTRACT

A simple, one-pot procedure for the synthesis of novel 3-phenyl-3,4-dihydro-2H-benzo[a][1,3] oxazino[5,6-c]phenazine derivatives by four-component coupling reaction between benzo[a]phenazine-5-ol, formaldehyde and amine in the presence of a catalytic amount ZnO-PTA@Fe₃O₄/EN-MIL-101(Cr) nanopowder in ethanol at room temperature under stirring condition. ZnO-PTA@Fe₃O₄/EN-MIL-101(Cr) An inorganic magnetic catalyst was analyzes and described by the XRD, TEM, FESEM, TGA, AFM, VSM and ICP-OES. This study presents simple, efficient, and one-pot multicomponent protocol, which provides several advantages such as short reaction times, high yields, easy working up, chromatography-free technique, catalyst recovery, and reusability are other highlights of this work.     

A prototype of an extrapolation chamber for beta radiation beams of 90Sr+90Y

Extrapolation chamber is the only primary standard dosimeter for beta radiation. With the aim to test new configurations and materials using easily-available and low-cost materials and fulfill the need of a chamber for scientific metrological purposes, in this paper the prototype of an extrapolation chamber has been built and its performance has been investigated in the beta radiation field of ⁹⁰Sr+⁹⁰Y. The main differences between the chamber and commercially available chambers are the geometry, constituent material and configuration. The obtained results were compared with those of the calibration certificate of the source and an agreement within 4 % was verified. The depth-dose curve was also obtained and compared with the curve published in ISO 6980, showing a good agreement. Moreover, Monte Carlo simulation was undertaken using MCNP4C code and the relative difference of 0.3 % was observed compared to the experiment. All of the results proved the suitability of the chamber in the beta radiation field of ⁹⁰Sr+⁹⁰Y.     

Preparation of Carvedilol Nanoparticles by Emulsification Method and Optimization of Drug Release: Surface Response Design Versus Genetic Algorithm

The objectives of this research were the production of Eudragit nanoparticles of carvedilol, an anti-hypertension drug, for enhancement of its absorption and optimization of drug release. Nanoparticles were prepared by emulsification-solvent evaporation or diffusion methods. The statistical surface response design, based on the Box-Behnken model, was applied to evaluate the effect of four variables, each in two levels, on specifications of nanoparticles. An intelligent modeling system was established according to genetic algorithm to predict drug release from the nanoparticles. The neural network-genetic algorithm model showed a more precise method than surface response design in the prediction of the release properties of carvedilol from Eudragit nanoparticles.     

Microfluidic Studies of Carbon Dioxide

Carbon dioxide (CO₂) sequestration, storage and recycling will greatly benefit from comprehensive studies of physical and chemical gas–liquid processes involving CO₂. Over the past five years, microfluidics emerged as a valuable tool in CO₂‐related research, due to superior mass and heat transfer, reduced axial dispersion, well‐defined gas–liquid interfacial areas and the ability to vary reagent concentrations in a high‐throughput manner. This Minireview highlights recent progress in microfluidic studies of CO₂‐related processes, including dissolution of CO₂ in physical solvents, CO₂ reactions, the utilization of CO₂ in materials science, and the use of supercritical CO₂ as a “green” solvent.     

Phenyl isothiocyanate in heterocyclic synthesis: Novel synthesis of thiazoles,thieno[2,3-b]pyridine,thiophene and thieno[3,2-c]pyridazine derivatives

Summary The enamino nitriles1 and2 react with phenyl isothiocyanate followed by cyclization with -haloketones3 and10 to afford in each case the thiazole5, thiophene11 and the thieno[2,3-b]pyridine derivatives19 and21. Chemical and spectroscopic evidences for the structures of the new compounds are described.

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Phenylisothiocyanate in der Heterocyclensynthese: Neue Synthesen für Thiazol-, Thieno [2,3-b]pyridin-, Thiophen- und Thieno[3,2-c]pyridazin-Derivate

Zusammenfassung Die Enamin-nitrile1 und2 ergaben nach Reaktion mit Phenylisothiocyanaten und nachfolgender Cyclisierung mit -Halogenketonen3 und10 die entsprechenden Thiazole5, die Thiophene11 und die Thieno[2,3-b]pyridine19 und21. Chemische und spektroskopische Untersuchungen wurden als Strukturbeweise für die neuen Verbindungen herangezogen.

     

Simulating pedestrian flow through narrow exits

Introduction: The flow of pedestrians through narrow doorways is one of the most common features of crowd motions and evacuations. It is particularly an important aspect of pedestrian simulations models since their accuracy depends highly on their ability to produce realistic exit flow rates. The problem has been extensively studied in the literature, but many aspects of it have remained controversial with mixed (and often contradictory) evidence emerging from different studies and different methods. Methods: We discuss the significance of parameter calibration for accurate simulation of pedestrian flow through narrow exits using social force model. Based on sensitivity analyses, we show how simulated exit throughput rate can vastly differ by changing the value of certain parameters. We identify the two parameters that are most critical, and then calibrate them based on a set of experimental observations (at macro level). Using these calibrated parameters, we then re-examine three fundamental questions related to pedestrian flow at bottlenecks, (1) the relation between desired velocity and simulated egress time; (2) the effect of barricade at exits; and (3) the effect of exit in the corner versus the middle. Results: Our numerical analyses showed that, with the calibrated parameters, increasing the desired velocity in the social-force model results in monotonically shorter egress times (at a marginal rate that rapidly diminishes as the desired velocity increases). We showed that placing a panel-like barricade at exit can facilitate the outflow and reduces the egress time, but its effect depends on the widths of exit, as well as the size of the barricade and its distance to exit. We show that the positioning the exit in the corner is also effective in terms of reducing egress time, but only for very narrow exits. The benefit diminishes quickly as the exit becomes wider. Applications: These outcomes demonstrated the significance of parameter calibration for accurate simulation of crowd flows. The findings may also help to identify simple modifications that can facilitate crowd flows at narrow bottlenecks.     

Synthesis of (E)-2-amino-N′-benzylidenehexahydroquinoline-3-carbohydrazide

Molecular Diversity - A one-pot, multi-component protocol for the synthesis of a new class of functionalized quinoline carbohydrazide derivatives via reaction of various anilines, dimedone,...     

Reliability assessment of different plate theories for elastic wave propagation analysis in functionally graded plates

The importance of elastic wave propagation problem in plates arises from the application of ultrasonic elastic waves in non-destructive evaluation of plate-like structures. However, precise study and analysis of acoustic guided waves especially in non-homogeneous waveguides such as functionally graded plates are so complicated that exact elastodynamic methods are rarely employed in practical applications. Thus, the simple approximate plate theories have attracted much interest for the calculation of wave fields in FGM plates. Therefore, in the current research, the classical plate theory (CPT), first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT) are used to obtain the transient responses of flexural waves in FGM plates subjected to transverse impulsive loadings. Moreover, comparing the results with those based on a well recognized hybrid numerical method (HNM), we examine the accuracy of the plate theories for several plates of various thicknesses under excitations of different frequencies. The material properties of the plate are assumed to vary across the plate thickness according to a simple power-law distribution in terms of volume fractions of constituents. In all analyses, spatial Fourier transform together with modal analysis are applied to compute displacement responses of the plates. A comparison of the results demonstrates the reliability ranges of the approximate plate theories for elastic wave propagation analysis in FGM plates. Furthermore, based on various examples, it is shown that whenever the plate theories are used within the appropriate ranges of plate thickness and frequency content, solution process in wave number-time domain based on modal analysis approach is not only sufficient but also efficient for finding the transient waveforms in FGM plates.     

Piroxicam/β-cyclodextrin complex included in cellulose derivatives-based matrix microspheres as new solid dispersion-controlled release formulations

New formulations capable to enhance piroxicam (PRX) water solubility and at the same time to control and adjust its release have been developed. For this purpose, two methods have been used and combined to achieve this goal, namely complexation and microencapsulation by O/W emulsion solvent evaporation. In order to modify the drug release, first, microparticles composed of pure PRX and ethylcellulose (EC) or mixtures of EC and hydroxypropylmethylcellulose (HPMC) were prepared, and then, other micropaticles containing the β-cyclodextrin/piroxicam (β-CD/PRX) complex obtained by the solvent evaporation technique and EC or a mixture of EC and HPMC were produced and tested. These formulations were characterized by FT-IR, XRD, optical microscopy, and SEM methods. Drug dissolution tests were carried out in acidic media at pH = 1.2 and 37°C. Depending on the microparticles composition, their size (d₁₀) ranged between 49 μ.m and 121 μ.m and PRX_loaded varied from 10.8 % to 27.7 %. The effect of complexation and HPMC polymer on the drug release was investigated; the results demonstrated that the Higuchi’s release constant significantly increased when using the EC/HPMC mixture as a matrix with pure PRX or only EC as a matrix with the β-CD/PRX complex. The results are remarkably promising since the combination of these processes provided new SD-CR formulations of piroxicam which enabled simultaneous enhancement and control of its release from the carriers.