A simple microscopic model for the dynamics of adhesive failure

We consider a microscopic model for the failure of soft adhesives in tension based on ideas of bond rupture under dynamic loading. By focusing on adhesive failure under loading at constant velocity, we demonstrate that bimodal curves of stress against strain may occur due to effects of finite polymer chain or bond length and characterize the loading conditions under which such bimodal behavior is observed. The results of this analysis are in qualitative agreement with experiments performed on unconfined adhesives in which failure does not occur by cavitation.     

Spin-resolved correlations in the warm-dense homogeneous electron gas

We have studied spin-resolved correlations in the warm-dense homogeneous electron gas by determining the linear density and spin-density response functions, within the dynamical self-consistent mean-field theory of Singwi et al. The calculated spin-resolved pair-correlation function g _{σ σ′}(r) is compared with the recent restricted path-integral Monte Carlo (RPIMC) simulations due to Brown et al. [Phys. Rev. Lett. 110, 146405 (2013)], while interaction energy E _int and exchange-correlation free energy F _xc with the RPIMC and very recent ab initio quantum Monte Carlo (QMC) simulations by Dornheim et al. [Phys. Rev. Lett. 117, 156403 (2016)]. g _↑↓(r) is found to be in good agreement with the RPIMC data, while a mismatch is seen in g _↑↑(r) at small r where it becomes somewhat negative. As an interesting result, it is deduced that a non-monotonic T-dependence of g(0) is driven primarily by g _↑↓(0). Our results of E _int and F _xc exhibit an excellent agreement with the QMC study due to Dornheim et al., which deals with the finite-size correction quite accurately. We observe, however, a visible deviation of E _int from the RPIMC data for high densities (~8% at r _s = 1). Further, we have extended our study to the fully spin-polarized phase. Again, with the exception of high density region, we find a good agreement of E _int with the RPIMC data. This points to the need of settling the problem of finite-size correction in the spin-polarized phase also. Interestingly, we also find that the thermal effects tend to oppose spatial localization as well as spin polarization of electrons.     

Enhancement of stability of growth,structural and NLO properties of KDP crystals due to additive along with seed rotation

Potassium Acetate (CH₃COOK) and Potassium Citrate (K₃C₆H₅O₇) as new additives were added into the potassium dihydrogen phosphate (KDP) solutions in different molar ratios. The metastable zone width and induction period with and without these additives were determined and compared. Dielectric measurements on pure and doped KDP crystals at various temperatures ranging from 313 to 423 K were carried out by the conventional parallel plate capacitor method which results low dielectric constant value dielectrics in doped crystals. The high resolution XRD studies show that CH₃COOK doped KDP crystal and K₃C₆H₅O₇ doped KDP crystal do not contain any internal structural grain boundaries and indicates that the crystalline perfection is very good. Moreover, the addition of these potassium additives improves the quality of the crystal and yields highly transparent crystals with well defined features. The effect of additives on the growth, nucleation kinetics, structural, NLO and optical properties has been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Molecular dynamics and structure-based virtual screening and identification of natural compounds as Wnt signaling modulators: possible therapeutics for Alzheimer’s disease

Molecular Diversity - Wnt signaling pathway is an evolutionarily conserved pathway responsible for neurogenesis, axon outgrowth, neuronal polarity, synapse formation, and maintenance....     

Selective oxoammonium salt oxidations of alcohols to aldehydes and aldehydes to carboxylic acids

The oxidation of alcohols to aldehydes using stoichiometric 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1) in CH(2)Cl(2) at room temperature is a highly selective process favoring reaction at the carbinol center best able to accommodate a positive charge. The oxidation of aldehydes to carboxylic acids by 1 in wet acetonitrile is also selective; the rate of the process correlates with the concentration of aldehyde hydrate. A convenient and high yield method for oxidation of alcohols directly to carboxylic acids has been developed.     

Naked eye detection of nitric oxide release from nitrosothiols aided by gold nanoparticles

In this work we have demonstrated that nitric oxide can be monitored spectrophotometrically using cyclodextrin encapsulated ferrocene. The detection course showed the colour change from yellow to blue which can be detected with the naked eye. Also we describe the catalytic effect of gold nanoparticles in enhancing nitric oxide release from S-nitrosothiols.     

Functional Military Textile: Plasma-Induced Graft Polymerization of DADMAC for Antimicrobial Treatment on Nylon-Cotton Blend Fabric

In this study, diallyldimethylammonium chloride (DADMAC), a quaternary ammonium salt monomer, is graft polymerized on 50?C50 Nylon-Cotton (NyCo) standard military fabric using atmospheric pressure glow discharge plasma to impart self-detoxification capability. Atmospheric pressure plasma?is used to induce free radical chain polymerization of the DADMAC monomer to introduce a graft polymerized network on the fabric with durable antimicrobial properties. Pentaerythritol tetraacrylate (PETA) is used as a cross-linking agent to obtain a highly cross-linked, durable polymer network. The presence of polyDADMAC on the fabric surface is confirmed using acid dye staining, SEM, and TOF?CSIMS. Antibacterial performance is investigated using standard AATCC Test Method 100 for both gram positive and gram negative bacteria. Results show 99.9?% reduction in the bacterial activities of Klebsiella pneumoniae and Staphylococcus aureus.     

Defect induced local moment in ZnO as a consequence of Stoner mechanism

We have examined the formation of a local moment by considering various defects in ZnO. The localization of the defect induced state is found to determine the presence/absence of a local moment. A lot of attention on the probable origin of magnetism in wide band gap oxides has focused on cation vacancies. Here we show that oxygen interstitial atoms give rise to a large magnetic moment which results in a spin polarization of both the conduction and valence bands, in addition to spin polarized gap states. A Stoner mechanism is invoked and the relevant Stoner parameters are determined to be 0.7 eV for an oxygen atom in the presence of an oxygen interstitial but reduced to 0.2 eV on oxygen in the presence of a Zn vacancy.     

Helical folding in heterogeneous foldamers without inter-residual backbone hydrogen-bonding

This communication describes a set of hybrid foldamers that do not feature inter-residual, but intra-residual backbone hydrogen-bonding, yet adopt a preferentially folded conformation displaying right-handed helical architecture. Conformational ordering is apparently due to the combined conformational restrictions imposed by the conformationally restricted individual amino acid residues with which the oligomers are made of.