Solving the nonlinear equations for one-dimensional nano-sized model including Rydberg and Varshni potentials and Casimir force using the decomposition method

The Adomian decomposition method has been applied to solve the nonlinear equations from the one-dimensional model for a nano-sized-oscillator. The model includes Rydberg and Varshni potentials as well as Casimir force with fractional damping. New approximate solution of the equations of motion for anharmonic vibrations of a nano-sized oscillator with the elastic force deriving from the Rydberg and Varshni potentials has been obtained.     

Novel optically active poly(amide-imide)s derived from L-aspartic acid

2,6-Bis-(2,5-dioxo-tetrahydro-N-(4-carboxyphenyl)pyrrol-3-yl)-pyrrolo[3,4-f]isoindole-1,3,5,7-teraone, a chiral diacid, was prepared from pyromellitic anhydride and L-aspartic acid in a three steps reaction pathway. The polycondensation reactions of the monomer with aromatic diamines were carried out in direct condensation reaction conditions. The synthesized poly(amide-imide)s had inherent viscosities in the range of 0.30–0.80 dl/g. Identification of all of the products were performed by conventional analytical techniques such as TLC, IR and ¹H NMR/¹³C MR spectroscopy. Thermoanalytical techniques (TGA/DSC) showed useful levels of thermal stability, associated with relatively high glass transition temperatures and carbonized residues in excess of 40% at 600°C for the synthesized polymers. Amorphous morphology was obtained based on XRD patterns and DSC traces. The polymers were soluble in a variety of polar organic solvents and afforded transparent and relatively flexible to brittle films by solution casting.     

Environmental Friendly Synthesis of Novel Isatin Ketal and Isatin Schiff Base Derivatives Using Michael Addition Reaction under Solvent‐Free Conditions

An efficient and simple procedure for the synthesis of novel isatin derivatives is described. Michael addition of aniline Schiff bases of isatin or p‐toluidine Schiff bases of isatin to fumaric esters affords the Michael adduct compounds in good to high yields in the presence of K₂CO₃ and tetrabutylammonium bromide (TBAB) under solvent‐free conditions. Repeating of this reaction about spiro[1,3‐dioxolane‐2,3′‐indol]‐2′(1′H)‐one, as a Michael donor, in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) gives Michael adducts in remarkable yields under the same conditions.     

Tetrabutylammonium bromide media aza-Michael addition of 1,2,3,6-tetrahydrophthalimide to symmetrical fumaric esters and acrylic esters under solvent-free conditions

The aza-Michael addition of 1,2,3,6-tetrahydrophthalimide with symmetrical fumaric esters has been performed efficiently in a solvent-free system at 100 °C and using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a base in the presence of tetrabutylammonium bromide (TBAB). The products were obtained in good to high yields within 2.5-7.0 h. This reaction worked well on linear alkyl fumarates and was not effective with nonlinear alkyl fumarates. Although the reaction was also applicable to acrylates such as n-butyl acrylate, methacrylates and crotonates were not suitable Michael acceptors for this reaction.     

Antioxidant and antimicrobial study of Schefflera vinosa leaves crude extracts against rice pathogens

Plant extracts are one of the best possible sources of bioactive molecules, and are being used globally as an antioxidants and natural antimicrobial compounds. In current study, Schefflera vinosa leaves extract was prepared through Soxhlet extraction procedure using methanol and chloroform as solvents. The extract was investigated for total antioxidant, phenolic and flavonoid contents, free radical scavenging and antimicrobial activities. The free radical scavenging activities were evaluated through 2,2- diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-3-ethylbenzotiazolin-6-sulfonic acid (ABTS) and Ferric-reducing/ antioxidant power (FRAP) assay. The antimicrobial activity of extract was determined through poisoned food method. The methanolic extract has exhibited high antioxidant, phenolic, and flavonoid activities compared to chloroform extract. Similarly, free radical scavenging activities (ABTS, DPPH and FRAP) were higher in methanolic extract. Further, Fourier-Transform Infrared Spectroscopy (FTIR) used to determine the functional group and Gas chromatography-mass spectrometry (GC–MS) to elucidate volatile composition of the crude extract. Different functional group like N-H, O-H, C-O, C-N, C-H, C=O, C≡C and C-O-H presence indicate the existence of many metabolites in the extracts. GC–MS study identified 61 compounds and subsequently, these molecules were screened virtually using DockThor. Furthermore, antimicrobial study was confirmed against rice pathogens like Magnaporthe oryzae (M. oryzae) and Xanthomonas oryzae pv. oryzae (Xoo). Molecular docking study further suggested that phytomolecules (3-Isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane, and 2-Methoxy-5-methylthiophene) targets Histone Deacetylase (HDAC) of M. oryzae and Peptide Deformylase (PDF) of Xoo, which could inhibit their growth. Hence, this study indicated that Schefflera vinosa extracts could be an important ingredient as an antioxidant as well as antimicrobial agent against rice pathogens.     

Transport properties of Mie(14,7) fluids: molecular dynamics simulation and theory

An extensive computer simulation study is presented for the self-diffusion coefficient, the shear viscosity, and the thermal conductivity of Mie(14,7) fluids. The time-correlation function formalism of Green-Kubo is utilized in conjunction with molecular dynamics (MD) simulations. In addition to molecular simulations, the results of a recent study [A. Eskandari Nasrabad, J. Chem. Phys. 128, 154514 (2008)] for the mean free volume are applied to calculate the self-diffusion coefficients within a free volume theory framework. A detailed comparison between the MD simulation and free volume theory results for the diffusion coefficient is given. The density fluctuation theory of shear viscosity is used to compute the shear viscosity and the results are compared to those from MD simulations. The density and temperature dependences of different time-correlation functions and transport coefficients are studied and discussed.     

Thermally stable polymers based on 1,3,4-oxadiazole rings

<正>In the present work,new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent.The obtained polymers are insoluble or slightly soluble in polar aprotic solvents such as DMSO and DMF. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers had improved thermal stabilities.The model reaction was also investigated and the resulting bis-l,3,4-oxadiazole compounds were characterized by conventional spectroscopic methods.     

Polyamides with pendant 1,3,4-oxadiazole and pyridine moieties

A novel aromatic diamine,2-（5-（3,5-diaminophenyl）-l,3,4-oxadiazole-2-yl）pyridine（POBD）,containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various aromatic and aliphatic diacid chlorides to generate a series of new aromatic polyamides with pendant 1,3,4-oxadiazole groups.The prepared polyamides were characterized by IR,elemental analysis and through the synthesis of model compounds.Thermophysical properties of the synthesized polyamides have been studied by DSC,TGA and inherent viscosity measurements. Relatively high inherent viscosity values（0.76-1.62 dL/g,in 0.125%H₂SO₄ at 25℃） were observed for these compounds. Number average molecular weight（M_n） of the polymers was measured by vapor phase osmometry（VPO）.The introduction of bulky side chains in the structure of aromatic polyamides led to increased solubility of these polymers in common polar and aprotic solvents,such as DMF,DMSO,NMP and DMAc,which allowed thin films to be cast from polymer solutions. The highest molecular weight（M_n = 51190） was observed for polymer（DC）,which was prepared from pyridine-2,6-dichlorocarbonyl.