Synthesis of pyrazol-quinazolinones and 2,3-dihydroquinazolin-4(1H)-ones using CoAl2O4 nanoparticles as heterogeneous catalyst

Journal of the Iranian Chemical Society - The preparation and characterization of cobalt aluminate (CoAl2O4) magnetic nanoparticles and its application as a catalyst for the synthesis of a novel...     

Minimization of Total Absolute Flow Time Deviation in Single and Multiple Machine Scheduling

In this note, single machine scheduling and minimizing absolute flow time deviation (TAFD) are considered. The relationship between this problem and the mean absolute deviation of job completion times about a common due date (MAD) is discussed. Based on the MAD problem optimal solutions of the TAFD problem are given. Furthermore, the generalization of the problem to the multiple machine case is discussed and an efficient algorithm for generating many optimal solutions of the problem, in the multi-machine case, is given.     

A first-principle DFT study of solvent effects on metiamide tautomers and imaginary interactions with H<Subscript>2</Subscript>-receptors

Metiamide is a class of medications called H₂-receptor antagonist or H₂ blockers. It decreases the amount of acid made in the stomach. It is commonly used in the treatment for peptic ulcer disease and gastroesophageal reflux disease. In this study, the metiamide tautomer stability, structural data, HOMO and LUMO (energies and shapes), ΔΕ _HOMO–LUMO gaps, UV–visible data and graphs, dipole moments, Mulliken charges, and thermodynamic and kinetic stabilities in aqueous media as a biological solvent and some of the different media (vacuum, H₂O, Et-OH and DMSO) were investigated for the tautomers of metiamide by the density functional theory DFT-B3LYP/6-31G* method. The results presented that the probability of the adaptability and compatibility of which tautomer (T1–T6) are better than the other tautomers for interactions with the pattern and structural map of the H₂-receptor. The diversities of the interaction points and mosaic patterns of the T3 and T4 tautomers in H₂O media with the imaginary H₂-receptor were investigated.     

Comparison of optical detection system ,PVDF detection system, and PVDF needle hydrophone for optoacoustic tomography

Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally with that by using thermoelastic waves as a broadband ultrasonic source. For the comparison, an optical stress transducer(OST), a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used.To ensure all of the detection systems interrogated by the same ultrasonic field, a small optical instrument that fixed the generating laser head was constructed. The sensitivity was evaluated by measuring signalto-noise ratios (SNRs) and noise equivalent pressures (NEPs). The PVDF system, with a 4-kPa NEP has a 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broad detection range.     

Preparation of titanium dioxide nanostructure from ilmenite through sulfate-leaching process and solvent extraction by D<Subscript>2</Subscript>EHPA

In this study, TiO₂ nanoparticles have been obtained from low-grade ilmenite ore via two consecutive acid digestion and solvent extraction processes. The as-extracted TiO₂ (Anatase phase) product was characterized using techniques such as XRD, XRF, FESEM, FTIR and BET surface area. Diluted sulfuric acid and D₂EHPA (bis-(2-ethyl-hexyl) phosphoric acid) were used as digester agent and an extraction solvent, respectively. The effects of main parameters such as recycling capacities and D₂EHPA concentration, as well as the extraction time and temperature on TiO₂ extraction were investigated. The results demonstrated that the best performance and efficiency for titanium and total iron uptake were 99 and 3.8%, respectively, at the lowest concentration of D₂EHPA.     

Vibrational analysis of electrostatically actuated microstructures considering nonlinear effects

The vibrational behavior of electrostatically actuated microstructures subjected to nonlinear squeeze film damping and in-plane forces is investigated. First-Order Shear Deformation Theory is used to model dynamical system by means of finite element method, while finite difference method is applied to solve the nonlinear Reynolds equation of squeeze film damping simultaneously. Vibrational analysis of microplates is performed by solving eigenvalue problem, after validating the model by pull-in phenomenon and transient behavior. In addition, considering nonlinear squeeze film damping and step-input actuations, response frequencies of microplates are calculated. Effect of ambient pressure and in-plane forces on dynamic pull-in phenomenon is also studied. Results for simplified models are verified and are in good agreement with the published literature. This investigation can reveal nonlinear vibrational behavior of microstructures.     

Identification of Weakly Nonlinear Systems Using Describing Function Inversion

In this paper describing functions inversion is used and the restoring force of a nonlinear element in a MDOF system is characterized. The describing functions can be obtained using linearized frequency response functions (FRFs). The response of the system to harmonic excitation forces at distinct frequencies close to the resonant frequency results in linearized FRFs. The nonlinear system can be approximated at each excitation frequency by an equivalent linear system. This approximation leads to calculation of the first-order describing functions. By having the experimental describing functions calculated and the system’s responses corresponding to the nonlinear element (measured or interpolated), nonlinear parameter identification can be performed. Two numerical and experimental case studies are provided to show the applicability of this method.     

Pore formation in phospholipid bilayers by amphiphilic cavitands

Five new cavitands were prepared that have four pendant n-undecyl chains and "headgroups" connected by 2-carbon spacers. The headgroups were ~OCH(2)CONH-Ala-OCH(3), 1; ~OCH(2)CONH-Phe-OCH(3), 2; ~OCH(2)CONH-Ala-OH, 3; ~OCH(2)CONH-Phe-OH, 4; and ~OCH(2)CONHCH(2)CH(2)-thyminyl, 5. Pore formation by each cavitand was studied by use of the planar bilayer conductance experiment. All five compounds were found to form pores in asolectin bialyer membranes. Compounds 1-3 behaved in a generally similar fashion and exhibited open-close dynamics. Compounds 4 and 5 formed pores more rapidly, were more dynamic, and led more quickly to membrane rupture. Differences in the ion transport activity are rationalized in terms of structure and aggregate cavitand assemblies.