Limit Theorems for Weighted Functionals of Cyclical Long-Range Dependent Random Fields

The article investigates isotropic random fields for which the spectral density is unbounded at some frequencies. Limit theorems for weighted functionals of these random fields are established. It is shown that for a wide class of functionals, which includes the Donsker scheme, the limit is not affected by singularities at non-zero frequencies. For general schemes, in contrast to the Donsker line, we demonstrate that the singularities at non-zero frequencies play a role even for linear functionals.     

Zeros of real polynomials

We study vector subspaces of the set of zeros of real valued symmetric odd polynomials and of real homogeneous polynomials of low degree.     

Regular high-nuclearity species from square building blocks: a triangular 3 × [2 × 2] Ni12 complex generated by the self-assembly of three [2 × 2] Ni4 molecular grids

A dodecanuclear 3 × [2 × 2] nickel(II) complex has been obtained via the self-association of three tetranuclear [2 × 2] molecular grids. X-ray diffraction shows a "propeller-like" structure of the [Ni(4)](3) scaffold with a central μ(3)-hydroxide. The dodecanuclear species remains stable in solution and can be deposited without decomposition on highly ordered pyrolytic graphite surfaces.     

Studies of electrochemical surface alloying and dealloying by in situ high-speed STM

The electrochemical formation and dissolution of a lead/copper surface alloy on Cu(100) in chloride-containing electrolyte solutions were studied on the atomic scale by in situ scanning tunneling microscopy with high temporal and spatial resolution. Alloy formation, induced by a negative potential sweep, starts predominantly at the Cu steps, followed by the formation of a novel transient (4 × 3) alloy phase with 0.25 ML Pb coverage, which continuously is transformed into the 0.375 ML coverage c(4 × 4) phase, observed under UHV conditions. Both of these phases consist of rows of Pb atoms embedded into the Cu surface and exhibit highly dynamic structural fluctuations on sub 100 ms time scales. Upon increasing the potential again, a second c(4 × 4) phase with a different appearance in the STM images forms, which is attributed to partial dealloying, involving desorption of Pb from energetically less favorable sites. Further dealloying results in the formation of ribbon-like structures, already reported in previous studies. These ribbons are shown to consist of Pb atoms decorating domain boundaries in the c(2 × 2) chloride adlayer, left behind on the Cu surface by the dissolving surface alloy phase. Furthermore, dynamic observations of the subsequent coarsening of the ribbon network and the attachment/detachment of isolated Pd adsorbates to the ribbons are presented. Both isolated Pb adsorbates and Pb atoms in the ribbons are proposed to be stabilized by coadsorbed Cl.     

3D Slicer as an image computing platform for the Quantitative Imaging Network

Quantitative analysis has tremendous but mostly unrealized potential in healthcare to support objective and accurate interpretation of the clinical imaging. In 2008, the National Cancer Institute began building the Quantitative Imaging Network (QIN) initiative with the goal of advancing quantitative imaging in the context of personalized therapy and evaluation of treatment response. Computerized analysis is an important component contributing to reproducibility and efficiency of the quantitative imaging techniques. The success of quantitative imaging is contingent on robust analysis methods and software tools to bring these methods from bench to bedside.     

Rapid detection of synthetic biomarkers of <Emphasis Type="Italic">Escherichia coli</Emphasis> in water using microAnalyzer: a field dependence study

Mixtures of 12 known volatile metabolites of Escherichia coli (2,5-dimethyltetrahydrofuran, dimethyl disulfide, 2-heptanone, 2,5-dimethylpyrazine, benzaldehyde, dimethyl trisulfide, 2-nonanone, nonanal, decanal, 2-undecanone, indole, and 2-tridecanone) were prepared from internal standards in water. The headspace gases were then analyzed using microAnalyzer™, a miniaturized Gas Chromatography-Differential Mobility Spectrometry (GC-DMS) system. Differential mobility spectra showed monomer peaks of the analytes with the observed retention times below 3 min. Dispersion voltages, determining the dependence of signal intensities and compensation voltages of each analyte on the applied radio frequency (RF) voltages, were recorded for positive and negative modes. It was found that at increasing RF voltages the monomer peaks of compounds of lower molecular masses tend to shift to more negative compensation voltages; whereas, those of higher molecular masses tend to shift to more positive compensation voltages. The shift results in increase separation among each peak. The signal intensities for all peaks, however, tend to decrease at higher RF voltages. The RF voltage which gave optimum peaks separation and signal resolution was 1,200 V (corresponds to 24 kV/cm). This study demonstrates the potential of microAnalyzer™ as an integrated gas chromatograph detector for a preliminary screening system in the on-site detection of E. coli in water. The operational principle of the instrument is also presented in this study.     

Characterizing TiO2(110) surface states by their work function

The unreconstructed TiO(2)(110) surface is prepared in well-defined states having different characteristic stoichiometries, namely reduced (r-TiO(2), 6 to 9% surface vacancies), hydroxylated (h-TiO(2), vacancies filled with OH), oxygen covered (ox-TiO(2), oxygen adatoms on a stoichiometric surface) and quasi-stoichiometric (qs-TiO(2), a stoichiometric surface with very few defects). The electronic structure and work function of these surfaces and transition states between them are investigated by ultraviolet photoelectron spectroscopy (UPS) and metastable impact electron spectroscopy (MIES). The character of the surface is associated with a specific value of the work function that varies from 4.9 eV for h-TiO(2), 5.2 eV for r-TiO(2), 5.35 eV for ox-TiO(2) to 5.5 eV for qs-TiO(2). We establish the method for an unambiguous characterization of TiO(2)(110) surface states solely based on the secondary electron emission characteristics. This is facilitated by analysing a weak electron emission below the nominal work function energy. The emission in the low energy cut-off region appears correlated with band gap emission found in UPS spectra and is attributed to localised electron emission through Ti(3+)(3d) states.     

Structural Water Drives Self‐assembly of Organic Rosette Nanotubes and Holds Host Atoms in the Channel

We reveal how water solvent determines the self‐assembly pathway and stability of organic rosette nanotubes (RNTs) and show their possible functions, using three‐dimensional molecular theory of solvation (a.k.a. 3D‐RISM). Structural water molecules penetrate the pockets on the RNT outer surface, form a wetting monolayer in the RNT channel and bridge RNT rosettes. We predict that the inner water shell might stabilize rare gas atoms inside the RNT channel, and envision molecular devices with RNT channels transporting water or holding guest molecules for targeted delivery.     

Synthesis of azabicyclo[n.1.0]alkane-derived bifunctional building blocks via the Corey–Chaykovsky cyclopropanation

An efficient approach towards the synthesis of monoprotected azabicyclo[5.1.0]octane-derived conformationally restricted γ-amino acids and diamines is reported. Optimization of the conditions for the key Corey–Chaykovsky reaction allowed the construction of two isomeric methanoazepane frameworks on a multigram scale in 55–65% yield. Additionally, the developed approach was used in the three-step synthesis of 3,4-methano-β-proline and its diamine derivatives.