On exact solutions for some oscillating motions of a generalized Oldroyd-B fluid

This paper deals with exact solutions for some oscillating motions of a generalized Oldroyd-B fluid. The fractional calculus approach is used in the constitutive relationship of fluid model. Analytical expressions for the velocity field and the corresponding shear stress for flows due to oscillations of an infinite flat plate as well as those induced by an oscillating pressure gradient are determined using Fourier sine and Laplace transforms. The obtained solutions are presented under integral and series forms in terms of the Mittag–Leffler functions. For α = β = 1, our solutions tend to the similar solutions for ordinary Oldroyd-B fluid. A comparison between generalized and ordinary Oldroyd-B fluids is shown by means of graphical illustrations.     

On exact solutions for some oscillating motions of a generalized Oldroyd-B fluid

This paper deals with exact solutions for some oscillating motions of a generalized Oldroyd-B fluid. The fractional calculus approach is used in the constitutive relationship of fluid model. Analytical expressions for the velocity field and the corresponding shear stress for flows due to oscillations of an infinite flat plate as well as those induced by an oscillating pressure gradient are determined using Fourier sine and Laplace transforms. The obtained solutions are presented under integral and series forms in terms of the Mittag–Leffler functions. For α = β = 1, our solutions tend to the similar solutions for ordinary Oldroyd-B fluid. A comparison between generalized and ordinary Oldroyd-B fluids is shown by means of graphical illustrations.     

Spatially Homogeneous Rotating Solution in f(R) Gravity and Its Energy Contents

In this paper, the metric approach of f(R) theory of gravity is used to investigate the exact vacuum solutions of spatially homogeneous rotating spacetimes. For this purpose, R is replaced by f(R) in the standard Einstein-Hilbert action and the set of modified Einstein field equations reduce to a single equation. We adopt the assumption of constant Ricci scalar which maybe zero or non-zero. Moreover, the energy density of the non-trivial solution has been evaluated by using the generalized Landau-Lifshitz energy-momentum complex in the perspective of f(R) gravity for some appropriate f(R) model, which turns out to be a constant quantity.     

Surface modification of platinum by laser-produced X-rays

Laser-induced plasma is used as an X-ray source for the growth of hillocks like nanostructures on platinum surface. To generate X-rays, plasma is produced by Nd:YAG laser, which is operated at second harmonics (λ?=?532?nm, E?=?400?mJ). Analytical grade 5?N pure Al, Cu and W are used as laser targets for X-rays production. X-rays produced from Al, Cu and W plasmas are used to irradiate three analytical grade (5?N pure) platinum substrates, respectively, under the vacuum ～10^?4 torr. XRD analysis shows considerable structural changes in the exposed platinum. The decrement in reflection intensities, increment in dislocation line density, change in d-spacing and disturbance in the periodicity of planes evidently prove these structural changes. Atomic force microscope AFM topographic analysis of the platinum exposed to X-rays emitted from Al, Cu and W targets showed that nanometer-size hillocks are produced on the platinum surface irrespective of the source. It has also been observed that due to these hillocks, the roughness of the surface has increased. Conductivity of hillocks produced from X-rays produced by Al, Cu and W targets is compared and it is shown that the hillocks produced by Al target X-rays have better conductivity compared to the hillocks produced by X-rays from Cu and W targets.     

Annealing of ion-implanted Ga0.47In0.53As

We have investigated annealing of ion-implanted GaInAs using transmission electron microscopy. We have found that the best condition for the post-implantation anneals for GalnAs is a 30 second anneal at a temperature of 700–800°C. This produces a material similar in character to the untreated GaInAs. Anneals for longer than 30 seconds produce crystal defects becoming increasingly complex with time for similar temperatures.     

Effect of ion beam irradiation on palladium (II) acetyl acetonate dispersed in polymer matrix

Composites, containing different concentrations of palladium (II) acetylacetonate in polymethyl methacrylate (PMMA) matrix were prepared by vigorous mixing. PMMA was prepared by solution polymerization technique. The composites were irradiated with a 120 MeV Ni¹⁰⁺ beam at two different fluences of 1×10¹¹ and 5×10¹² ions/cm² to study ion-induced effects on their dielectric, structural properties and surface morphology. AC electrical properties of these samples were studied in the frequency range 100 Hz to 10 MHz. The dielectric permittivity/loss shows frequency dependent behavior and it obeys the universal law of dielectric (i.e. ?α f ^n?1) for pristine and irradiated samples at high frequency. The crystalline size and crystallinity of the composites were studied by X-ray diffraction analysis. Decrease in peak intensity after irradiation signifies the amorphization which is also responsible for decrease in T _g as obtained by means of differential scanning calorimetry measurement. Fourier transform infrared spectra also support this result. Surface roughness increases upon irradiation as observed from scanning electron microscopy.     

Insights into the binding mechanism of 2,5-substituted 4-pyrone derivatives as therapeutic agents for fused dimeric interactions: A computational study using QTAIM,dynamics and docking simulations of protein–ligand complexes

The study is focused on examining 2,5-Substituted 4-Pyrone based compounds through quantum chemical and topological analysis techniques, evaluating the properties of these compounds, including their geometrical structure, intermolecular interactions and assess their possible applications. Additionally, the molecular stability, charge delocalization and UV-Visible data was investigated and compared with the calculated energy and oscillator strength using the TD-DFT approach. The researchers observed that charge transfer occurred within the molecule, indicated by the HOMO and LUMO energies. It was also found that the compound exhibited planarity and higher chemical reactivity. The calculated Mulliken charges and molecular electrostatic potential were used to interpret the Fukui index data that help predict reactive sites and understand the reactivity patterns of specific atoms in a compound. The study is aimed to understand the role of NCI in the molecule under investigation using electron localization functions and localized orbit locator methods. Molecular docking and ADMET studies were conducting involving a detailed MD simulation of a protein-ligand complex using the OPLS3e force field and the SPC water model. These findings could prove to be beneficial in developing new therapeutic agents with various pharmacological effects and potential toxicities.     

Biocatalysis for C–S bond formation: Porcine pancreatic lipase (PPL) catalysed thiolysis/hydrothiolation reactions in sole water

In this paper, a biocatalytic route is described wherein PPL, lipase from porcine pancreas, in conjunction with water on reaction with different thiophenols and styrene oxides undergo thiolysis with C-S bond formation without the use of any metal catalysts, oxidants, bases, additives or organic solvents towards formation of β-hydroxysulfides in good to excellent yields with high regioselectivity at room temperature. Furthermore, PPL also facilitates thiophenols to undergo hydrothiolation with styrenes or phenylacetylenes in sole water and thus forming linear thioethers or vinylsulfides respectively via C–S bond formation. In addition to the straightforward and atom-efficient protocol, a gram-scale synthesis of β-hydroxysulfide and recyclability for three consecutive cycles without decrease in efficiency of PPL make our biocatalytic protocol for constructing C–S bond highly valuable from both environmental and economic viewpoints than traditional chemical practices.     

Small Ubiquitin-Like Modifier Protein 3 Enhances the Solubilization of Human Bone Morphogenetic Protein 2 in <Emphasis Type="Italic">E. coli</Emphasis>

Small ubiquitin-like modifier (SUMO) fusion technology is widely used in the production of heterologous proteins from prokaryotic system to aid in protein solubilization and refolding. Due to an extensive clinical application of human bone morphogenetic protein 2 (hBMP2) in bone augmentation, total RNA was isolated from human gingival tissue and mature gene was amplified through RT-PCR, cloned (pET21a), sequence analyzed, and submitted to GenBank (Accession no. KF250425). To obtain soluble expression, SUMO3 was tagged at the N-terminus of hBMP2 gene (pET21a/SUMO3-hBMP2), transferred in BL21 codon+, and ~?40% soluble expression was obtained on induction with IPTG. The dimerized hBMP2 was confirmed with Western blot, native PAGE analysis, and purified by fast protein liquid chromatography with 0.5 M NaCl elution. The cleavage of SUMO3 tag from hBMP2 converted it to an insoluble form. Computational 3D structural analysis of the SUMO3-hBMP2 was performed and optimized by molecular dynamic simulation. Protein-protein interaction of SUMO3-hBMP2 with BMP2 receptor was carried out using HADDOCK and inferred stable interaction. The alkaline phosphatase assay of SUMO3-hBMP2 on C2C12 cells showed maximum 200-ng/ml dose-dependent activity. We conclude that SUMO3-tagged hBMP2 is more suited for generation of soluble form of the protein and addition of SUMO3 tag does not affect the functional activity of hBMP2.     

New insights into the transition pathway from nonspecific to specific complex of DNA with Escherichia coli integration host factor

To elucidate the nature of the transition-state ensemble along the reaction pathway from a nonspecific protein-DNA complex to the specific complex, we have carried out measurements of DNA bending/unbending dynamics on a cognate DNA substrate in complex with integration host factor (IHF), an architectural protein from E. coli that bends its cognate site by approximately 180 degrees . We use a laser temperature jump to perturb the IHF-DNA complex and monitor the relaxation kinetics with time-resolved FRET measurements on DNA substrates end-labeled with a FRET pair. Previously, we showed that spontaneous bending/kinking of DNA, from thermal disruption of base-pairing/-stacking interactions, may be the rate-limiting step in the formation of the specific complex (Kuznetsov, S. V.; Sugimura, S.; Vivas, P.; Crothers, D. M.; Ansari, A. Proc. Natl. Acad. Sci. USA 2006, 103, 18515). Here, we probe the effect of varying [KCl], which affects the stability of the complex, on this rate-limiting step. We find that below approximately 250 mM KCl, the observed relaxation kinetics are from the unimolecular bending/unbending of DNA, and the relaxation rate kr is independent of [KCl]. Above approximately 300 mM KCl, dissociation of the IHF-DNA complex becomes significant, and the observed relaxation process includes contributions from the association/dissociation step, with kr decreasing with increasing [KCl]. The DNA bending step occurs with a positive activation enthalpy, despite the large negative enthalpy change reported for the specific IHF-DNA complex (Holbrook, J. A.; Tsodikov, O. V.; Saecker, R. M.; Record, M. T., Jr. J. Mol. Biol. 2001, 310, 379). Our conclusion from these studies is that in the uphill climb to the transition state, the DNA is kinked, but with no release of ions, as indicated by the salt-independent behavior of k(r) at low [KCl]. Any release of ions in the unimolecular process, together with conformational changes in the protein-DNA complex that facilitate favorable interactions and that contribute to the negative enthalpy change, must occur as the system leaves the transition state, downhill to the final complex.