Functional one,two, and three-dimensional ZnO structures by solvothermal processing

Crystalline zinc oxide (ZnO) has been fabricated by solvothermal techniques under quite different temperature and pressure environment stretching from sub- to supercritical conditions. Among them, one-step processing of inorganic–inorganic hybrid ZnO structures based on ZnO substrate with attached ZnO nanocrystals has been challenged. Combination of doping ions was made to yield ZnO structures with luminescent properties of high potential for application in fast-decay devices. The room temperature decay of antimony, lithium (Sb, Li) codoped homoepitaxial films is reported.     

Site-sensitive X-ray photoelectron spectroscopy of Fe3O4 by photoelectron diffraction

Fe 2p core-level photoelectron spectra of magnetite were measured using soft X-ray and hard X-ray, and its emission angle dependence was investigated. The photoelectron diffraction pattern from different atomic sites differs because the atomic arrangement surrounding each site is different. By selecting the forward-focusing-peak (FFP) directions characteristic to each atomic site and measuring the kinetic energy dependence of the FFP intensities at the Fe 2p core-level range, we succeed in detecting the variation of the peak intensity of Fe 2p core-level spectra at different emission directions. This result, consistent with recent results, suggests that the lower-binding-energy peak of the Fe 2p core-level spectrum may be assigned as the B site component.     

High‐sensitivity simultaneous quantification of tacrolimus and 13‐O‐demethyl tacrolimus in human whole blood using ultra‐performance liquid chromatography coupled to tandem mass spectrometry

Blood concentrations of tacrolimus show large variability among patients and the narrow therapeutic range is related to adverse effects. Therefore, therapeutic drug monitoring is needed for strict management. 13‐O‐Demethyl tacrolimus (13‐O‐DMT) was reported as the major metabolite formed by cytochrome P450 (CYP)3A such as CYP3A5. In previous studies, the best lower limit of quantification (LLOQ) was 0.1 ng/mL for both substances. However, this LLOQ may not be low enough now because the dosage of tacrolimus has decreased in recent years. The purpose of this study was to develop and validate a high‐sensitivity and high‐throughput assay for simultaneous quantification of tacrolimus and 13‐O‐DMT in human whole blood using ultra‐performance liquid chromatography with tandem mass spectrometry (UPLC–MS/MS). Thirty‐five stable kidney transplant recipients receiving tacrolimus were recruited in this study. The calibration curve range was 0.04–40 ng/mL. All calibration samples and quality control samples fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation. Trough concentrations of tacrolimus and 13‐O‐DMT in 35 stable kidney transplant recipients receiving tacrolimus were within the range of the respective calibration curve. Our novel UPLC–MS/MS method is more sensitive than previous methods for quantification of tacrolimus and 13‐O‐DMT.     

Non-Gaussian quasi-likelihood estimation of SDE driven by locally stable Lévy process

We address estimation of parametric coefficients of a pure-jump Lévy driven univariate stochastic differential equation (SDE) model, which is observed at high frequency over a fixed time period. It is known from the previous study (Masuda, 2013) that adopting the conventional Gaussian quasi-maximum likelihood estimator then leads to an inconsistent estimator. In this paper, under the assumption that the driving Lévy process is locally stable, we extend the Gaussian framework into a non-Gaussian counterpart, by introducing a novel quasi-likelihood function formally based on the small-time stable approximation of the unknown transition density. The resulting estimator turns out to be asymptotically mixed normally distributed without ergodicity and finite moments for a wide range of the driving pure-jump Lévy processes, showing much better theoretical performance compared with the Gaussian quasi-maximum likelihood estimator. Extensive simulations are carried out to show good estimation accuracy. The case of large-time asymptotics under ergodicity is briefly mentioned as well, where we can deduce an analogous asymptotic normality result.     

Dipolar Nanocars Based on a Porphyrin Backbone

The design and synthesis of a new family of nanocars is reported. To control their motion, we integrated a dipole which can be tuned thanks to strategic donor and acceptor substituents at the 5- and 15-positions of the porphyrin backbone. The two other meso positions are substituted with ethynyltriptycene moieties which are known to act as wheels. Full characterization of nine nanocars is presented as well as the electrochemistry of these push-pull molecules. DFT calculations allowed us to evaluate the magnitude of the dipoles and to understand the electrochemical behavior and how it is affected by the electron donating and accepting groups present. An X-ray crystal structure of one nanocar has also been obtained.     

Mechanistic study on radiation-induced grafting into fluorinated polymer solid films using a swelling-induced detachment of grafted polymers

The radiation-induced graft polymerization (RGP) of styrene into poly(ethylene-co-tetrafluoroethylene) films was performed at various monomer concentrations and solvents at 60 °C. The grafted polystyrene (g-PS) was isolated using the swelling-induced detachment phenomenon, and the number-averaged molecular weight (Mn) and the number of g-PS (Np) were determined using gel permeation chromatography. The Mn increased consistently with an increase in the grafting time up to 2–3 hours, indicating very low termination rates, which was a result of the “gel effect”. This is the first direct evidence of the gradual Mn increase over time using RGP in thermally and chemically stable polymer films such as fluorinated polymers. When the Mn and Np were plotted as a function of the degree of grafting (DOG), sudden Np drops along with rapid Mn increases were observed in the DOG region of 80–90%, indicating negligible initiation and propagation; however, a recombination termination between two propagating g-PS radicals dominated the later part of the grafting process. Further increases in both Mn and Np were observed subsequently, implying that reinitiation and propagation events were triggered by morphological changes, as observed by small- and ultrasmall-angle X-ray scattering experiments, which liberated the dormant radicals from the lamellar crystals.     

A Possible Nuclear Spin Dewar. Hyperfine Interactions of Short-Lived β Emitter 8Li and 12B in TiO2

It was confirmed by detecting the β-NMR of ¹²B (I ^π=1⁺, T _1/2=20.2 ms) in a TiO₂ (rutile) crystal that the nuclear spin polarization of ¹²B was totally maintained in the crystal as produced through a nuclear reaction before implantation. Two locations, site 1 and site 2, were found with the relative populations 9 and 1, respectively, and the electric field gradients (EFGs) at those sites were obtained to be q(site 1)=+(37.1±0.5)10¹⁵ V/cm², η(site 1)<0.03, q(site 2)=+(185±5)10¹⁵ V/cm² and η(site 2)=0.62±0.02. We also found that about 30% of the initial polarization of ⁸Li (I ^π=2⁺, T _1/2=838 ms) was maintained in the crystal. Since the polarizations of other β emitting nuclei, ^12,16N, ^13,19O, and ⁴¹Sc were also totally maintained in the crystal, the crystal can be a “Spin Dewar” in which many short-lived nuclides can be implanted with their polarizations totally maintained during their lifetimes for the studies not only on the electronic structure of impurities in it but also on the nuclear properties. This revised version was published online in September 2006 with corrections to the Cover Date.