Quantum flux-based resonances in solitonic vortices

Working with the Nielsen–Olesen Lagrangian in static cylindric coordinates, we derive the system of coupled field equations and perform a first-order perturbative approach, pointing out an interesting contribution connected to the London–Heitler current. For an r,θ-depending scalar boson, evolving in a constant or zero magnetic field we get, besides the flux quantization and the Landau energy levels, a less expected structure of the scalar modes whose radial and azimuthal parts are decoupled by the presence of the quantized magnetic flux.     

Central intertwining lifting,maximum entropy and their permanence

The central intertwining lifting is used to establish a maximum principle for the commutant lifting theorem. This maximum principle is used to prove that the central intertwining lifting is also a maximal entropy solution for the commutant lifting theorem, when T is a unilateral shift of finite multiplicity. The maximum principle is based on the residual spaces for intertwining liftings, and is motivated by Robinson's minimum energy delay principle for outer functions. A permanence property for the central intertwining lifting is also given.     

YAG:Ce and YAP:Ce – Suitable Fast Detectors for Transmission Mössbauer Spectroscopy

Yttrium aluminum garnet and perovskite activated by cerium are fast mechanically and chemically resistant scintillation materials. Their mechanical properties enable easy and precise machining. Both scintillation materials have a decay time shorter than 100 ns and, therefore, are suitable to use for high counting rates. The luminescence maximum of YAP:Ce and YAG:Ce are 360 and 550 nm, respectively. Their luminescence bands correspond with the sensitivity spectral range of the most widely used photomultipliers. Moreover, the semiconductor light detectors can be used with YAG:Ce scintillation crystals. Theoretical and experimental comparative analysis of characteristics for both YAP:Ce and YAG:Ce detectors and good experience over relatively long periods of using these detectors allow us to draw a conclusion regarding their unconditional advantages over other commonly used detectors for transmission Mössbauer spectroscopy. The considerable improvement in data production enhances the capabilities of Mössbauer spectroscopy as a research and analytical tool.     

Determination of pesticides fenoxycarb and permethrin by sequential injection chromatography using miniaturized monolithic column

Sequential injection chromatography system equipped with miniaturized 10 mm monolithic column was used for fast simultaneous determination of two pesticides—fenoxycarb (FC) and permethrin (PM). The system was composed of a commercial sequential injection analysis (SIA) system (FIAlab^® 3000, 6-port selection valve and 5.0 mL syringe pump), commercially available column Chromolith™ RP-18e (10 mm × 4.6 mm i.d.) (Merck^®, Germany) and CCD UV-vis detector (USB 2000, Ocean-optics) with 1.0 cm Z-flow cell, absorbance was monitored at 225 nm. The mobile phase used for analysis was acetonitrile/water (60:40, v/v), flow rates were 0.6 mL min⁻¹ for elution of fenoxycarb and 1.2 mL min⁻¹ for elution of permethrin. For each analysis 4.8 mL of mobile phase was used. The chromatographic resolution between both compounds was >8 and analysis time was <6.5 min under the optimal conditions. Limits of detection were determined at 2.0 μg mL⁻¹ for fenoxycarb and 1.0 μg mL⁻¹ for permethrin. Samples were prepared by diluting with mobile phase and injected volume was 10 μL for each analysis. Developed method was applied to analysis of both pesticides in veterinary pharmaceutical foams and sprays ARPALIT^® Neo (Aveflor, Czech Republic). SIC method was compared with validated method (HPLC, reverse phase 100 mm monolithic column, gradient elution).     

Amperometric Detection of 4‐Chlorophenol on Two Types of Expanded Graphite Based Composite Electrodes

The assessment of an expanded graphite‐Ag‐zeolite‐epoxy composite (EG‐Z‐Ag‐Epoxy) electrode for the determination of 4‐chlorophenol (4‐CP) is described and compared to the corresponding expanded graphite‐epoxy composite (EG‐Epoxy) electrode. Cyclic voltammetry was used to characterize the electrochemical behavior and determination of 4‐CP at both electrodes in 0.1 M Na₂SO₄ and 0.1 M NaOH supporting electrolytes. A substantial enhancement of sensitivity for the determination of 4‐CP at the EG‐Z‐Ag‐Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric quantification. Also, under these last conditions the lowest limit of detection of 1 μM illustrates the analytical versatility of this electrode in a concentration range where aquatic 4‐chlorophenol pollution is known to occur.     

Simultaneous Determination of Acetaminophen and Ascorbic Acid at an Unmodified Boron‐Doped Diamond Electrode by Differential Pulse Voltammetry in Buffered Media

A boron‐doped diamond electrode (BDDE) was used for the simultaneous anodic determination of L ‐ascorbic acid (AA) and acetaminophen (AC) in aqueous buffered media by differential pulse voltammetry (DPV). Linear calibration plots of anodic current peaks versus concentration were obtained for both analytes in the concentration range 0.01–0.1 mM with very high correlation coefficients. RSD of 2–3% and high sensitivities were obtained from DPV data in single and dicomponent systems. The potential applicability of the DPV technique associated with standard addition was illustrated by simultaneous determination of AA and AC in real sample solutions made up from pharmaceutical products.     

A luminescent sensor for tyrosine phosphorylation

We have developed a luminogenic probe for tyrosine phosphorylation based on a short peptide sequence containing an iminodiacetate moiety near the site of phosphorylation. In response to kinase activity, the probe provides a strong luminescence enhancement, resulting from the increased ability of the probe to bind and sensitize Tb3+ and Eu3+ ions upon phosphorylation.     

Reaction of graphite fluoride with NaOH-KOH eutectic

Graphite fluoride has been generally considered chemically inert against strong alkalis under ambient conditions. In the present study we demonstrate that treatment of graphite fluoride with eutectic NaOH-KOH mixture at 250 °C induces dramatic structural and textural changes in the solid as evidenced by XRD, FT-IR, Raman, UV-vis absorption and fluorescence and microscopy techniques (TEM, AFM). The reaction proceeds in the molten state leading to water-soluble, graphitized carbon particles which unlike graphite fluoride, adopt a variety of morphologies, like platy, tetragonal, triangular, discoid and spherical. The resulting carbon particles are dispersible in water and fluoresce under UV excitation.     

Soft Null Hypotheses: A Case Study of Image Enhancement Detection in Brain Lesions

This work is motivated by a study of a population of multiple sclerosis (MS) patients using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to identify active brain lesions. At each visit, a contrast agent is administered intravenously to a subject and a series of images are acquired to reveal the location and activity of MS lesions within the brain. Our goal is to identify the enhancing lesion locations at the subject level and lesion enhancement patterns at the population level. We analyze a total of 20 subjects scanned at 63 visits (～30Gb), the largest population of such clinical brain images. After addressing the computational challenges, we propose possible solutions to the difficult problem of transforming a qualitative scientific null hypothesis, such as “this voxel does not enhance,” to a well-defined and numerically testable null hypothesis based on the existing data. We call such procedure “soft null” hypothesis testing as opposed to the standard “hard null” hypothesis testing. This problem is fundamentally different from: (1) finding testing statistics when a quantitative null hypothesis is given; (2) clustering using a mixture distribution; or (3) setting a reasonable threshold with a parametric null assumption. Supplementary materials are available online.     

Reactions of P4S10 and pyPS2Cl with N,N′-diphenylurea and N,N′-diphenylthiourea

The reaction of P₄S₁₀ (1) with N,N′-diphenylurea (PhNH)₂CO (2) results in new heterocyclic compounds: the pyridinium salt of 1,3-diphenyl-2-sulfido-2-thioxo-1,3-diaza-2λ⁵-phosphetidine (3) (with a P–N–C–N cycle) and the pyridinium salt of 1,4-diphenyl-2,5-disulfido-2,5-dithioxo-1,4-dithiadiaza-2λ⁵,5λ⁵-diphosphinane (4), containing the (P–S–N)₂ cycle and the cyclic thiophosphates [pyH]₂[P₂S₈] (5), [pyH]₂[P₂S₇] (6) and [pyH]₃[P₃S₉] (7). A similar reaction, but carried out with N,N′-diphenylthiourea (PhNH)₂CS (8), leads to the formation of 4 and 6. pyPS₂Cl (9), used as an alternative starting material, also yields compounds 3, 4, 5, and further [pyH][PS₂Cl₂] (10) and S₈ after reaction with 2. Compound 3 reacts with Pd(CH₃COO)₂, with the formation of the complex [Pd(Ph₂N₂COPS₂)₂] (11). The crystal structures of 3 and 7 were determined by single-crystal X-ray diffraction.