Young-type interference in (e, 2e) ionization of H(2)

We have investigated the electron impact single ionization of the hydrogen molecule, with fully determined kinematics. The experimental and theoretical results are compared with He ionization under the same conditions. The results indicate that the ejected electron angular distribution for H(2) is modified due to Young-type interference between ionization amplitudes for scattering from the two centers in the hydrogen molecule. The observable result is a suppression of the backward scattering (recoil) peak compared with the binary peak.     

Chemorheology investigation of a glassy epoxy thermoset on tensile plastic flow and fracture morphology

Reproducible and uncharacteristic tensile stress–strain behavior of cured glassy epoxy‐amine networks produces distinctive fracture surfaces. Test specimens exhibiting plastic flow result in mirror‐like fracture surfaces, whereas samples that fail during yield or strain softening regions possess nominal mirror‐mist‐hackle topography. Atomic force microscopy and scanning electron microscopy reveal branched nodule morphologies in the 50‐nm size scale that may be responsible for the unusual tensile properties. Current hypothesis is that plastic flow of the glassy thermoset occurs through the existence and deformation of these nodular nanostructures. The thermal cure profile of the epoxy‐amine thermoset affects the size and formation of the nodular nanostructure. Eliminating vitrification during thermoset polymerization forms a more continuous phase, reduction in size of the nodules, and eliminates the capacity of the material to yield in plastic flow. This maximizes nanostructure connectivity of the glassy epoxy‐amine thermoset and reduces strain to failure significantly. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1333–1344.     

Deficiency of optineurin enhances osteoclast differentiation by attenuating the NRF2-mediated antioxidant response

Abnormally increased resorption contributes to bone degenerative diseases such as Paget’s disease of bone (PDB) through unclear mechanisms. Recently, the optineurin (OPTN) gene has been implicated in PDB, and global OPTN knockout mice (Optn^−/−) were shown to exhibit increased formation of osteoclasts (osteoclastogenesis). Growing evidence, including our own, has demonstrated that intracellular reactive oxygen species (ROS) stimulated by receptor activator of nuclear factor kappa-B ligand (RANKL) can act as signaling molecules to promote osteoclastogenesis. Here, we report that OPTN interacts with nuclear factor erythroid-derived factor 2-related factor 2 (NRF2), the master regulator of the antioxidant response, defining a pathway through which RANKL-induced ROS could be regulated for osteoclastogenesis. In this study, monocytes from Optn^−/− and wild-type (Optn^+/+) mice were utilized to differentiate into osteoclasts, and both qRT-PCR and tartrate-resistant acid phosphatase (TRAP) staining showed that the Optn^−/− monocytes exhibited enhanced osteoclastogenesis compared to the Optn^+/+ cells. CellROX^® staining, qRT-PCR, and Western blotting indicated that OPTN deficiency reduced the basal expression of Nrf2, inhibited the expression of NRF2-responsive antioxidants, and increased basal and RANKL-induced intracellular ROS levels, leading to enhanced osteoclastogenesis. Coimmunoprecipitation (co-IP) showed direct interaction, and immunofluorescence staining showed perinuclear colocalization of the OPTN-NRF2 granular structures during differentiation. Finally, curcumin and the other NRF2 activators attenuated the hyperactive osteoclastogenesis induced by OPTN deficiency. Collectively, our findings reveal a novel OPTN-mediated mechanism for regulating the NRF2-mediated antioxidant response in osteoclasts and extend the therapeutic potential of OPTN in the aging process resulting from ROS-triggered oxidative stress, which is associated with PDB and many other degenerative diseases.Subject terms: Mechanisms of disease, Stress signalling     

Modelling of point defects in monoclinic zirconia

We present the results of plane wave density functional theory calculations of oxygen vacancies and interstitial oxygen atoms in monoclinic zirconia. After calculating the incorporation energies and structures of interstitial oxygen atoms and formation energies of neutral oxygen vacancies, we consider the electron affinities and ionisation potentials of these defects. These properties are especially important at the silicon/oxide interface in MOSFET devices, where silicon may serve as an electron and hole source. The results demonstrate that interstitial oxygen atoms and positively charged oxygen vacancies can trap electrons if the electron source (band offset) is higher than ∼2 eV above the top of the zirconia valence band.     

Spatially Directed Pyrolysis via Thermally Morphing Surface Adducts

Combustion is often difficult to spatially direct or tune associated kinetics—hence a run-away reaction. Coupling pyrolytic chemical transformation to mass transport and reaction rates (Damköhler number), however, we spatially directed ignition with concomitant switch from combustion to pyrolysis (low oxidant). A ‘surface-then-core’ order in ignition, with concomitant change in burning rate,is therefore established. Herein, alkysilanes grafted onto cellulose fibers are pyrolyzed into non-flammable SiO₂ terminating surface ignition propagation, hence stalling flame propagating. Sustaining high temperatures, however, triggers ignition in the bulk of the fibers but under restricted gas flow (oxidant and/or waste) hence significantly low rate of ignition propagation and pyrolysis compared to open flame (Liñán's equation). This leads to inside-out thermal degradation and, with felicitous choice of conditions, formation of graphitic tubes. Given the temperature dependence, imbibing fibers with an exothermically oxidizing synthon (MnCl₂) or a heat sink (KCl) abets or inhibits pyrolysis leading to tuneable wall thickness. We apply this approach to create magnetic, paramagnetic, or oxide containing carbon fibers. Given the surface sensitivity, we illustrate fabrication of nm- and μm-diameter tubes from appropriately sized fibers.     

Uncertainties of method performance statistics based on a balanced completely randomized model interlaboratory study

Using exact and asymptotic distributions, formulas were developed to derive population variances and uncertainties, and their corresponding unbiased estimates, for the method performance statistics, i.e., the sample mean (y..), the repeatability variance and standard deviation and (s2r and sr), and the reproducibility variance and standard deviation (s2R and sR) and obtained from collaborative study of an analytical method.     

Transparent flexible ZnO/MWCNTs/pbma ternary nanocomposite film with enhanced mechanical properties

Functional organic-inorganic nanocomposites with high transparency show significant potential application in many fields. However, it is still a great challenge to prepare flexible transparent nanocomposites due to the intrinsic stiffness of the nanoparticles and the poor interaction between nanoparticles and organic matrices. In this work, a transparent ternary nanocomposite film with enhanced mechanical performance is fabricated by two-steps. First, the transparent ternary ZnO/MWCNTs/n-butyl methacrylate (BMA) nanodispersion is prepared by mixing the ZnO/BMA and MWCNTs/BMA dispersions directly. Then, the ternary nanocoposites film is fabricated via in-situ bulk polymerization of the above nanodispersions. As a result, the tensile strength of the ZnO/MWCNTs/poly-n-butyl methacrylate (PBMA) ternary film is enhanced by 42% and the elongation at break is three times that of ZnO/PBMA nanocomposite. The hardness of the film increases from 5B to 1H with 40 wt% ZnO. These results indicate that ZnO and MWCNTs can improve the mechanical properties of the composite significantly. Importantly, the ternary nanocomposite film still remains high transparency and exhibit excellent UV-shielding performance. The as-prepared transparent multifunctional nanocomposite films have promising applications in optical materials and devices, such as optical filters, contact lenses and protection packing.