Modified Kudryashov method via new exact solutions for some conformable fractional differential equations arising in mathematical biology

In this study, the modified Kudryashov method is used to construct new exact solutions for some conformable fractional differential equations. By implementing the conformable fractional derivative and compatible fractional complex transforms, the fractional generalized reaction duffing (RD) model equation, the fractional biological population model and the fractional diffusion reaction (DR) equation with quadratic and cubic nonlinearity are discussed. As an outcome, some new exact solutions are formally established. All solutions have been verified back into its corresponding equation with the aid of maple package program. We assure that the employed method is simple and robust for the estimation of the new exact solutions, and practically capable for reducing the size of computational work for solving a various class of fractional differential equations arising in applied mathematics, mathematical physics and biology.     

Ligand promoted and controlled palladium-catalyzed intramolecular Heck reaction of homoallyl alcohols: a facile synthesis of cyclopentaannulated quinolines

Bidentate phosphine ligands in palladium-catalyzed intramolecular Heck reactions of 2-chloroquinolin-3-yl-(1-homoallyl)alcohols are described to afford facile synthesis of 3-methylene-2,3-dihydro-1H-cyclopenta[b]quinolines in improved yields. We further observed using bulky aromatic phosphine ligand in Pd-catalyzed intermolecular Heck coupling reaction at olefinic centers with iodobenzene also favored exclusively Heck products in excellent yield.     

Unprecedented π···π interaction between an aromatic ring and a pseudo-aromatic ring formed through intramolecular H-bonding in a bidentate Schiff base ligand: crystal structure and DFT calculations

A combination of a single crystal X-ray diffraction study and density functional theory calculations has been applied to a bidentate Schiff base compound to elucidate different cooperative non-covalent interactions involved in the stabilization of the keto form over the enol one in the solid state. The single crystal X-ray structure reveals a remarkable supramolecular assembly of the keto form through a cyclic hydrogen bonded dimeric motif. The most interesting feature in the supramolecular assembly is the formation of a 'dimer of dimer' motif by π···π, CH···π and N···O/O···O interactions in which the π···π interaction involving the aromatic phenyl ring and the intramolecularly hydrogen bonded pseudo-aromatic ring of the keto form lying just above or below the phenyl ring of the other dimer seems to be unprecedented. The optimized geometry of the hydrogen bonded dimeric motif of the keto form of the organic molecule has been obtained by DFT calculations and agrees very well with that found within the crystalline state. The X-ray crystallographic geometry of the 'dimer of dimer' has also been computed, which shows that in the HOMO, the π electrons are localized in the phenyl rings away from each other, while in the LUMO, there is a strong π-π interaction between the phenyl ring of one dimer with the pseudo-aromatic ring of another dimer with an energy estimated to be 7.95 kJ mol(-1). Therefore, on HOMO → LUMO excitation there is localization of π electrons in the central part of the complex moiety which plays a stabilizing role of the dimer of dimer motif in the solid state.     

Robust 1D open rack-like architecture in coordination polymers of Anderson POMs [{Na4(H2O)14}{Cu(gly)}2][TeMo6O24] and [{Cu(en)2}3{TeW6O24}]: synthesis, characterization and heterogeneous catalytic epoxidation of olefines

Two novel organic-inorganic hybrid tungsto- and molybdo-telurates having formula [{Na(4)(H(2)O)(14)}{Cu(gly)}(2)][TeMo(6)O(24)] (1){gly = glycine} and [{Cu(en)(2)}(3){TeW(6)O(24)}]·6H(2)O {en = ethyline-diamine} (2) based on Anderson type heteropolyoxometalates (POMs) have been synthesized and characterized by X-ray crystallography. Common structural feature of both 1 and 2 is the presence of a unique 1D open rack-like architecture, where the disc shaped Anderson POMs act as steps and cationic Cu-organic complexes act as handles of the rack. In 1 the independent structural unit is a 1D coordination polymer with the above mentioned rack type architecture, while in 2, these independent rack-like architectures are further extended to a 2D coordination polymer. Heterogeneous catalysis for the epoxidation of cyclohexene and styrene by complexes 1 and 2 showed very good catalytic efficiency resulting epoxides of ~60% yield, with dialcohol formed by the hydrolysis of epoxides, as the other major product (~28%). Cyclic voltammetric studies of [{Na(4)(H(2)O)(14)}{Cu(gly)}(2)][TeMo(6)O(24)] (1) in aqueous KCl solution indicates that the redox changes occur only on the copper centers and supported by carrying out parallel experiments on the precursors like ([Cu(gly)(2)](2+) and [TeMo(6)O(24)](6-), under the identical experimental conditions. The E(1/2) = 0.662, -0.142 and -0.332 V(vs. SCE) correspond to Cu(III) → Cu(II), Cu(II) → Cu(I) and Cu(I) → Cu(0) reductions, respectively. Thermal analyses reveal identical phase transition reactions with an exothermic peak in the DTA curve at 380 °C for 1 and an endothermic peak appears at comparatively higher temperature (408 °C) for 2 manifesting the higher stability of tungstane based POM over the molybdenum ones. EPR as well as magnetic moment results indicate that both the complexes 1 and 2 are paramagnetic with one unpaired electron per copper(II) ion.     

Tuning stability of mesoporous silica films under biologically relevant conditions through processing with supercritical CO2

Mesoporous materials have been proposed for use in numerous biological environments such as substrates for cell culture and controlled release for drug delivery. Although mesoporous silica synthesis is facile, recent reports (Dunphy et al. Langmuir 2003, 19, 10403; Bass et al. Chem. Mater. 2007, 19, 4349) have demonstrated instability (dissolution) of pure mesoporous silica films under biologically relevant conditions. In this work, we demonstrate a simple processing handle (pressure) to control the dissolution of mesoporous silica films that are synthesized using preformed template films and supercritical CO 2. Spectroscopic ellipsometry is utilized to quantify changes in both the film thickness and porosity; these properties provide insight into the dissolution mechanism. The pore size increases as the films are exposed to phosphate-buffered saline (PBS) through preferential dissolution at the pore wall in comparison to the film surface; a mechanism reminiscent of bulk erosion of scaffolds for drug delivery. Thin mesoporous silica film lifetimes can be extended from several hours using traditional sol-gel approaches to days by using CO 2 processing for identical film thickness. Osteoblast attachment and viability on these films was found to correlate with their increased stability. This enhanced stability opens new possibilities for the utilization of mesoporous silica for biological applications, including drug delivery and tissue engineering.     

Measurements of elastic scattering for 7Be, 7Li + 9Be systems and fusion cross sections for 7Li + 9Be system

Elastic scattering angular distributions have been measured for ⁷Be + ⁹Be system at E_lab = 17, 19 and 21 MeV in the angular range θ_cm=26^○–58°, and for ⁷Li + ⁹Be system at E_lab= 15.75, 24 and 30 MeV. An optical model (OM) analysis of these data have been carried out. For the ⁷Li + ⁹Be system fusion cross sections were obtained at E_lab = 15.75, 24 and 30 MeV by measuring the α-evaporation spectra from the compound nucleus at backward angles. The measured α-evaporation spectra were reproduced by the statistical model calculations and fusion cross sections were extracted therefrom. The ratios of the experimental fusion cross sections to the total reaction cross sections (obtained form OM analysis) were found to be rather small. This result suggests that break-up process has a strong influence on fusion process leading to a reduction in fusion cross section.     

Improved normal-phase and reversed-phase gradient high-performance liquid chromatography procedures for the analysis of retinoids and carotenoids in human serum, plant and animal tissues.

Two high-performance liquid chromatography (HPLC) procedures, a rapid normal-phase isocratic method for the analysis primarily of retinol and retinoic acid on a 3 mu silica column, and a reversed-phase gradient method for the simultaneous analysis of retinoids and very polar to nonpolar carotenoids on a 3 mu C18 column, are described. The normal-phase isocratic HPLC procedure is rapid (12 min), requires a sample size of 100 microl or less of serum, and is suitable for routine analysis of retinol in any serum, and of retinol and retinoic acid in serum after administration of retinoic acid. The reversed-phase gradient method is suitable for the simultaneous analysis of very polar to nonpolar carotenoids such as epoxy-xanthophylls and xanthophyll esters, along with other carotenoids and retinoids that occur normally in human serum and other plant and animal tissues. A run time of 30-70 min is necessary, depending on the presence or absence of xanthophyll esters in the sample.     

Nearly Degenerate Isomers of C(BH)2: Cumulene,Carbene, or Carbone?

The ground electronic state of C(BH)₂ exhibits both a linear minimum and a peculiar angle‐deformation isomer with a central B‐C‐B angle near 90°. Definitive computations on these species and the intervening transition state have been executed by means of coupled‐cluster theory including single and double excitations (CCSD), perturbative triples (CCSD(T)), and full triples with perturbative quadruples (CCSDT(Q)), in concert with series of correlation‐consistent basis sets (cc‐pVXZ, X=D, T, Q, 5, 6; cc‐pCVXZ, X=T, Q). Final energies were pinpointed by focal‐point analyses (FPA) targeting the complete basis‐set limit of CCSDT(Q) theory with auxiliary core correlation, relativistic, and non‐Born–Oppenheimer corrections. Isomerization of the linear species to the bent form has a minuscule FPA reaction energy of 0.02 kcal mol^?1 and a corresponding barrier of only 1.89 kcal mol^?1. Quantum tunneling computations reveal interconversion of the two isomers on a timescale much less than 1 s even at 0 K. Highly accurate CCSD(T)/cc‐pVTZ and composite c～CCSDT(Q)/cc‐pCVQZ anharmonic vibrational frequencies confirm matrix‐isolation infrared bands previously assigned to linear C(BH)₂ and provide excellent predictions for the heretofore unobserved bent isomer. Chemical bonding in the C(BH)₂ species was exhaustively investigated by the atoms‐in‐molecules (AIM) approach, molecular orbital plots, various population analyses, local mode vibrations and force constants, unified reaction valley analysis (URVA), and other methods. Linear C(BH)₂ is a cumulene, whereas bent C(BH)₂ is best characterized as a carbene with little carbone character. Weak B–B attraction is clearly present in the unusual bent isomer, but its strength is insufficient to form a CB₂ ring with a genuine boron–boron bond and attendant AIM bond path.     

Dinitroaliphatics as linkers: application in the synthesis of novel artemisinin carba-dimer

Abstract  

The versatility of nitroaliphatics is demonstrated by using it in the syntheses of artemisinin derived dimers. A few novel artemisinin derived dimer and monomer have been synthesized using nitroalkane as linker.     

13C-NMR spectral studies on the distribution of substituents in some cellulose derivatives

¹³C-NMR spectra of trityl cellulose (Tr-Cell), tosyl cellulose (Ts-Cell), cellulose S-methyl xanthate (Cell-M-Xan), and cellulose formate (CF) in dimethylsulfoxide-d₆ were analyzed at 50.4 MHz. It was found that the distribution of substituents in the anhydroglucose units of these cellulose derivatives can be estimated from their ring carbon spectra. The results showed that (i) in Tr-Cell having degree of substitution (DS) lower than 1, the hydroxyl groups at C-6 carbon position are selectively tritylated, (ii) in the case of Ts-Cell, the difference in the relative DS value among three different types of hydroxyl groups is not large, although the relative reactivities of hydroxyl groups toward tosylation decrease in the order C-6 > C-2 > C-3, (iii) in Cell-M-Xan, the hydroxyl groups at C-3 carbon position are mainly substituted, and (iv) the ease of formylation is C-6 > C-2 > C-3. The 100.8 MHz ¹³C-NMR spectra of O-methyl cellulose (MC) revealed that the reactivity order in commercial MC prepared from alkali cellulose is C-6 ? C-2 > C-3. Concerning MC, its water solubility was also discussed in terms of the distribution of substituents along the cellulose chain.