Analysis of noncircular fluid-filled boreholes in elastic formations using a perturbation model

This paper presents a perturbation model to obtain flexural mode dispersions of noncircular fluid-filled boreholes in homogeneous elastic formations. The perturbation model is based on Hamilton's principle with a modified procedure for the reference state selection in order to handle the directional sensitivity of the flexural modes. The accuracy of the perturbation model has been confirmed by comparison to boundary integral solutions. Numerical results confirm that for a fast formation, even modes, and for a slow formation, odd modes are more sensitive to changes in the borehole elongation and azimuth. Even though the focus of this work is on elliptical boreholes and breakouts, the formulation is valid for any kind of noncircular borehole.     

Synthesis of quercetin-encapsulated alginate beads with their antioxidant and release kinetic studies

Abstract

In this present study, different forms of quercetin encapsulated beads were synthesized, namely ionic cross-linked gel beads and cryogel beads. Fourier Transform Infrared (FT-IR) spectra of the beads were used to characterize and prove quercetin encapsulation in alginate beads. Swelling and drying profiles were studied. Besides, release kinetics of quercetin molecules from gel beads and cryogels were carefully investigated in two different solvent/media; dimethyl sulfoxide (DMSO) and Roswell Park Memorial Institute Medium (RPMI-1640). Based upon the release kinetic studies, it is found that quercetin release from alginate cryogel beads fits the first-order release model in DMSO and it depends on the concentration of quercetin in the beads. The release of quercetin from alginate gel beads was described by the Higuchi release model, which highlights the release of quercetin molecules through the pores of the matrix. In RPMI-1640, the release of quercetin from both forms of alginate beads fits zero-order release model and it indicates a constant release of quercetin per unit time. Finally, the radical scavenging activity of the quercetin quantities was tested by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and successful results were obtained compared to reference material.     

Synthesis and characterization poly(ϵ-caprolactone-b-ethylene glycol-b-ϵ-caprolactone) ABA type block copolymers via “Click” chemistry and ring-opening polymerization

Synthesis of poly(?-caprolactone-b-ethylene glycol-b-?-caprolactone) ABA type block copolymer by “click” chemistry and ring-opening polymerization (ROP) was reported by using propargyl polyethylene glycol (propargyl-PEG) and terminally azido poly(?-caprolactone) ester (PCL-N₃). For this purpose, primarily propargyl-PEG was synthesized by using reaction of PEGs (3000 Da, 2000 Da, 1500 Da, 1000 Da, 600 Da ve 400 Da) and propargyl chloride. 3-azido-1-propanol was obtained by using chemical interaction of 3-chloro-1-propanol and sodium azide. Synthesis of PCL-N₃ was carried out by means of ROP of ?-caprolactone and 3-azido-1-propanol. Finally, poly(?-caprolactone-b-ethylene glycol-b-?-caprolactone) ABA type block copolymers were synthesized by using PCL-N₃ and propargyl-PEG. The primary parameters such as concentration, time, and temperature that influenced the reactions were assessed. The product characterization was achieved using NMR, FT-IR, GPC, elemental analysis, and fractional precipitation [non-solvent (petroleum ether-mL)/solvent (THF-mL)] techniques.     

Fusion systems and constructing free actions on products of spheres

We show that every rank two p-group acts freely and smoothly on a product of two spheres. This follows from a more general construction: given a smooth action of a finite group G on a manifold M, we construct a smooth free action on ${M \times \mathbb S^{n_1}\times \dots \times \mathbb S^{n_k}}$ when the set of isotropy subgroups of the G-action on M can be associated to a fusion system satisfying certain properties. Another consequence of this construction is that if G is an (almost) extra-special p-group of rank r, then it acts freely and smoothly on a product of r spheres.     

Investigation of thin-layer chromatography properties of some transition metal complexes based on ditiocarbamates

Sodium diethyldithiocarbamate (DEDTC) and ammonium pyrolidinedithiocarbamate (PyDTC) are prepared as their Co or Cu (M) complexes [M(DEDTC)(2) and M(PyDTC)(2), respectively]. The complexes are prepared by reactions of DEDTC and PyDTC with metal (II) nitrates, and they are examined for chromatographic properties using thin-layer chromatography systems. These complexes and their mixtures are spotted on the activated and non-activated 250-microm thick thin layers of commercial silica gel (Si-60GF(254)). Pure toluene and a toluene-cyclohexane mixture (3:1, v/v) are used as mobile phases for running the complexes. These chromatographic systems are successfully used for the qualitative analysis of the corresponding metal cations and the separation of components in both M(DEDTC)(2) and M(PyDTC)(2) complex mixtures. In addition, non-activated layers are more successful than activated layers. This study may be useful in understanding the effects of stationary and mobile phase properties, retention mechanisms, and the effects of the nature of metal and ligand type on the chromatographic behavior and parameters [e.g., retention factors, theoretical plate numbers, and resolution] of the complexes.     

Esterified porphyrazine complexes: Synthesis,characterization, aggregation behavior,and theoretical study

Magnesium porphyrazine having eight 5-hydroxypentylthio groups at the peripheral positions, was synthesized from 2,3-bis(5-hydroxypentylthio) maleonitrile. By the esterification reaction of octakis(5-hydroxypentylthio) porphyrazinato] Mg(II) with 3,4,5-trimethoxybenzoic acid in dicyclohexylcarbodiimide and toluene-p-sulfonic acid, esterified MgPz appending [5-thiopentyl 2-methoxy-4,6-bis(trifluoromethyl) benzoate] substituent was obtained. Further reaction of the metal-free porphyrazine with Co(II), Cu(II), Zn(II), and Fe(II) acetates have produced the metallo-porphyrazines. By reacting FePzCl with pyridine or pyrazine, the monomeric bis-axial and the oligomeric complexes were synthesized as the novel stable complexes, respectively. Their characterizations were performed by using elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR, mass and UV-Vis spectral data. The aggregation investigations carried out in different concentrations indicate that 3,4,5-trimethoxybenzyloxy-substituted porphyrazine compounds do not have any aggregation behavior in different concentrations. Quantum chemical computations were also done to the structural and electronic properties of target compounds.     

Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force

Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived “rule of thumb” expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4 cm acoustic aperture, and for a two-dimensional array of 4 × 4 cm² acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86 MHz, and 0.79 MHz, respectively, when the target depth is 4 cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9 MHz and 0.86 MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well.     

Synthesis,characterization, and investigations of antimicrobial activity of 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4(5H)-dione

Chalcone-like compounds 3a–l, 2-(benzylidene)-3,4-dihydronaphthalen-1(2H)-one, were synthesized from the addition of different benzaldehyde derivatives (2a–l) to 1,2,3,4-tetrahydro-1-napthalone (1) in basic medium. Mn(OAc)₃-mediated addition of dimedone (4) to chalcone-like compounds gave the spirobenzofuran derivatives (5a-l), 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4 (5H)-dione, in good yields. The structures of synthesized compounds 5a–l were elucidated on basis of spectral data (NMR, IR) and elemental analysis. In addition, their antibacterial activities were screened against some human pathogenic microorganisms.     

Cooperative grey games and the grey Shapley value

This contribution is located in the common area of operational research and economics, with a close relation and joint future potential with optimization: game theory. We focus on collaborative game theory under uncertainty. This study is on a new class of cooperative games where the set of players is finite and the coalition values are interval grey numbers. An interesting solution concept, the grey Shapley value, is introduced and characterized with the properties of additivity, efficiency, symmetry and dummy player, which are straightforward generalizations of the corresponding properties in the classical cooperative game theory. The paper ends with a conclusion and an outlook to future studies.