Numerical solution of Bloch–Gruneisen function to determine the contribution of electron–phonon interaction in polycrystalline MgB2 superconductor

Here, we report the efficient and feasible analytical method for the generalized Bloch–Gruneisen law in association with Debye temperature and various temperatures range in terms of incomplete gamma function. In addition, our results are in agreement with previous reports as shown in this letter. Bloch–Gruneisen function describes the contribution of electron–phonon interaction to the results of temperature dependence behavior of resistivity for integer and noninteger values of index m. In conclusion, the algorithm is constructed in Fortran 90 language for replicate the variation of temperature dependence of resistivity for pristine MgB₂ sample. Moreover, the comparison of numerical results with the proposed method reveals the validity and precision of the method.     

Aggregation, adsorption, and surface properties of multiply end-functionalized polystyrenes

The properties of polystyrene blends containing deuteriopolystyrene, multiply end-functionalized with C8F17 fluorocarbon groups, are strikingly analogous to those of surfactants in solution. These materials, denoted FxdPSy, where x is the number of fluorocarbon groups and y is the molecular weight of the dPS chain in kg/mol, were blended with unfunctionalized polystyrene, hPS. Nuclear reaction analysis experiments show that FxdPSy polymers adsorb spontaneously to solution and blend surfaces, resulting in a reduction in surface energy inferred from contact angle analysis. Aggregation of functionalized polymers in the bulk was found to be sensitive to FxdPSy structure and closely related to surface properties. At low concentrations, the functionalized polymers are freely dispersed in the hPS matrix, and in this range, the surface excess concentration grows sharply with increasing bulk concentration. At higher concentrations, surface excess concentrations and contact angles reach a plateau, small-angle neutron scattering data indicate small micellar aggregates of six to seven F2dPS10 polymer chains and much larger aggregates of F4dPS10. Whereas F2dPS10 aggregates are miscible with the hPS matrix, F4dPS10 forms a separate phase of multilamellar vesicles. Using neutron reflectometry (NR), we found that the extent of the adsorbed layer was approximately half the lamellar spacing of the multilamellar vesicles. NR data were fitted using an error function profile to describe the concentration profile of the adsorbed layer, and reasonable agreement was found with concentration profiles predicted by the SCFT model. The thermodynamic sticking energy of the fluorocarbon-functionalized polymer chains to the blend surface increases from 5.3kBT for x = 2 to 6.6kBT for x = 4 but appears to be somewhat dependent upon the blend concentration.     

Optical absorption and NMR spectroscopic studies on paramagnetic neodymium(III) complexes with beta-diketone and heterocyclic amines. The environment effect on 4f-4f hypersensitive transitions

The optical absorption spectra of [Nd(acac)3(H2O)2].H2O, [Nd(acac)3bpy] and [Nd(acac)3phen(H2O)2] (where acac=acetylacetone, bpy=2,2'-bipyridyl and phen=1,10-phenanthroline) complexes in the visible region, in a series of non-aqueous solvents (methanol, ethanol, isopropanol, chloroform, acetonitrile, pyridine, nitrobenzene and dimethylsulphoxide) have been analyzed. The transition 4G(5/2)<--4I(9/2) (Nd-VI) located near the middle of the visible region (17,500 cm(-1)) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f-4f transitions. The oscillator strength of this transition for the chelate as well as its adducts with phen and bpy in any of the solvent employed is larger than the oscillator strength of Nd3+ aqua-ion. It is most intense in pyridine for all the complexes studied and, therefore, pyridine is the most effective in promoting f-f spectral intensity. The band shape and oscillator strength of the hypersensitive transitions display pronounced changes as compared to Nd3+ aqua-ion. The band shapes of the hypersensitive transitions show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of change in the environment about the Nd(III) ion in the various solutions and suggests change in the environment about the Nd(III) ion in the various solutions and suggests coordination of solvent molecule(s), in some cases. A comparative account of hypersensitivity in the present complexes with those of other adducts of Nd(beta-diketoenolate)3 with heterocyclic amines is discussed. The NMR signals of heterocyclic amines have been shifted to high fields while the resonances due to acetylacetone moiety have moved to low fields. The paramagnetic shift in the complexes is dipolar in nature.     

Therapeutic Potential of DNAzyme Loaded on Chitosan/Cyclodextrin Nanoparticle to Recovery of Chemosensitivity in the MCF-7 Cell Line

Commonly, acquired resistances to anticancer drug are mediated by overexpression of a membrane-associated protein that encode via multi-drug resistance gene-1 (MDR1). Herein, the mRNA-cleaving DNAzyme that targets the mRNA of MDR1 gene in doxorubicin-resistant breast cancer cell line (MCF-7/DR) loaded on the chitosan β-cyclodextrin complexes was used as a tropical agent. Chitosan/β-cyclodextrin complexes were used to deliver DNAzymes into cancer cells. Determination of the physicochemical characteristics of the particles was done by photon correlation spectroscopy and scanning electron microscopy. The encapsulation efficiency of the complexes was tested by using gel retardation assay. Positively charged nanoparticles interacted with DNAzyme that could perform as an efficient DNAzyme transfection system. The rationale usage of this platform is to sensitize MCF-7/DR to doxorubicin by downregulating the drug-resistance gene MDR1. Results demonstrated a downregulation of MDR1 mRNAs in MCF-7/DR/DNZ by real-time PCR, compared to the MCF-7/DR as control. WST1 assay showed the 22-fold decrease in drug resistance on treated cells 24 h after transfection. Results showed the intracellular accumulation of Rh123 increased in the treated cells with DNAzyme. Results suggested a potential platform in association with chemotherapy drug for cancer therapy and indicated extremely efficient at delivery of DNAzyme in restoring chemosensitivity.

     

Cyclisation of optically active dihydromyrcenes (2,6-dimethyl-2,7-octadiene): A stereospecific ring contraction

The isomeric (+) and (?)-dihydromyrcene cyclise in organic acids through a stereospecific ring contraction process to give the esters of α-(S)-(+)-1-(α-hydroxyethyl)-3,3-dimethylcyclohexane and α(R)-(?)-1-(α-hydroxyethyl)-3,3-dimethylcyclohexane respectively. Small amounts of enantiomeric cis- and trans-tetrahydroeucarvyl esters are also formed. The absolute configuration of the chiral carbinol centres has been determined using Horeau's method. Also, the synthesis of both optical isomers of 3,3-dimethylcyclohexanol has been achieved for the first time.     

Molecular complexation of free base meso-tetraarylporphyrins with antimony(III) chloride in free solvent media

The reaction of meso-tetraarylporphyrins (H₂t(Xp)p) with SbCl₃ under free solvent conditions affords green complexes with a 1:1 H₂t(X)pp:SbCl₃ ratio. These complexes have dimeric structures with a (μ-Cl)₂bridge. UV–VIS, ¹H NMR and ¹³C NMR spectra data show that the porphyrin core of [(H₂t(Xp)p)₂Sb₂Cl₆], similar to 1:2 (donor:acceptor) molecular complexes of meso-tetraarylporphyrins and porphyrin diacid, is distorted, thus two nitrogen atoms of pyrrolenine in a side of the porphyrin plane act as electron donors to an antimony atom of SbCl₃. Molecular complexation of meso-tetraarylporphyrins with SbCl₃ produces a large downfield shift for the NH signal, although there is no hydrogen bonding present.     

Evaluation of the bond energy terms for the various types of boron-nitrogen bonds

Summary We have determined a series of bond energy terms in compounds containing dative, single, double and/or triple boron-nitrogen bonds. We describe various interesting applications based on these bond energy terms namely the determination of enthalpies of atomization and stabilization energies. More particularly, the conventional ring strain energies of three- and four-membered small ring containing boron and nitrogen atoms could be determined and the aromaticity of borazine, reexamined.Dedicated to Professor Alberte Pullman     

TEMPO-catalyzed aerobic oxidation of alcohols to aldehydes and ketones in ionic liquid [bmim][PF6

[reaction: see text]. A simple and mild TEMPO-CuCl catalyzed aerobic oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones in ionic liquid [bmim][PF6] with no trace of overoxidation to carboxylic acids has been developed. The product can be isolated by a simple extraction with organic solvent, and the ionic liquid can be recycled or reused.     

Theoretical Approach to the Deformation-induced Luminescence in Metals

The present paper reports the mechanoluminescence (ML) produced during fracture of metals. The mechanism of ML in metals is based on the generation of holes during the decay of mobile dislocations on the surface and subsequent electron-hole radiative recombination. The following equation is derived for the transient ML intensity of the fracto-induced ML in metals . The above equation shows that I should be maximum for a particular value of time t. For β 〉 α, . This equation shows that I should decrease exponentially with time. For the fracto-induced ML in metals, t_M and I_m may be expressed by the following equations . The spectroscopy of ML in metals is also discussed. A good correlation is found between the theoretical and experimentals results.     

Sol–gel behavior of a novel nanodroplet biomaterial for drug delivery

Nanodroplets can be considered as those nano/microemulsions in which the oil itself forms the active agent and the droplet size ambits in the nanometer range. Eugenol is an anti-inflammatory agent and its nanodroplet gel (NDG) has immense potential for topical use. Topical gels oblige some rheological characteristics to nail down the demands of proper application, stability and storage. Thus, the purpose of our study was to comprehend the effect of eugenol on the sol–gel tranisition properties of its NDGs. Towards this goal nanodroplets of eugenol were prepared and evaluated and the three selected nanodroplet formulations with 5, 10 and 5% v/v eugenol were converted into topical gel formulation using 1% w/w Carbopol 940. The NDGs were characterized using frequency sweep, creep recovery and thixotropy. All these tests pointed out that eugenol concentration has significant effect on the sol–gel behavior of NDGs. The NDGs exhibited more viscous (sol) properties than elastic (gel) properties as observed from the frequency sweep studies. The thixotropy of the NDGs was found to decrease with increase in eugenol concentration. Efforts have been made to explain the study results using mechanistic approach. The outcomes of our research studies could be of great use in future endeavors towards development of a topical NDG of eugenol with tailored sol–gel behavior.