Integral inequalities related to the Tchebychev semigroup

We study the semigroup (P _t ) _t≥0 generated by the operator

Development and fundamental investigation of Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS)

Glow Discharge (GD) spectroscopy is a well known and accepted technique for the bulk and surface composition analysis, while laser ablation (LA) provides analysis with high spatial-resolution analysis in LIBS (laser-induced breakdown spectroscopy) or when coupled to inductively coupled plasma spectrometry (ICP-OES or ICP-MS). This work concerns the construction of a Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS) instrument to study the analytical capabilities resulting from the interaction of a laser-generated sample plume with a pulsed glow discharge. Two ablation configurations were studied in detail. In a first approach, the laser-generated plume was introduced directly into the GD, while the second approach generated the plume inside the GD. The ablated material was introduced at different times with respect to the discharge pulse in order to exploit the efficient ionization in the GD plasma. For both LA-GD configurations, direct ablation into the afterglow of the pulsed glow discharge leads to an ion signal enhancement of up to a factor of 7, as compared to the ablation process alone under the same experimental conditions. The LA-GD enhancement was found to occur exclusively in the GD afterglow, with a maximum ablation S/N occurring in a few hundred microseconds after the termination of the glow discharge. The duration of the enhanced signal is about two milliseconds. Both the laser pulse energy and the position of the ablation plume (with respect to the sampling orifice) were found to affect the amount of mass entering the afterglow region and consequently, the enhancement factor of ionization.     

Reaction of 2‐Imino‐2H‐chromene‐3‐carboxamide with Phosphorus Isothiocyanates: First Synthesis of Novel Chromeno[2,3‐d]pyrimidinyl and Bis(chromeno[2,3‐d]pyrimidinyl)phosphines and Chromeno[2′,3′:4,5]pyrimido[2,1‐d][1,3,5,2]triazaphosphinine

Novel chromeno[2,3‐d]pyrimidinyl and bis(chromeno[2,3‐d]pyrimidinyl)phosphines and chromeno[2′,3′:4,5]pyrimido[2,1‐d][1,3,5,2]triazaphosphinine were obtained in a simple one‐pot procedure via treatment of 2‐imino‐2H‐chromene‐3‐carboxamide with phenyl phosphorus isothiocyanates. Possible reaction mechanisms were proposed. The structures of the obtained products were confirmed by elemental analyses and spectral tools.     

Untangling electronic,elastic and bonding properties of the ThGeO<Subscript>4</Subscript> host material from first principles calculation

We investigate the electronic, thermodynamic and bonding properties of the ThGeO₄ host material by means of pseudo-potential method within the framework of density functional theory. Zircon-type ThGeO₄ is found to undergo a pressure-driven phase transition to tetragonal scheelite structure, and beyond to monoclinic fergusonite ones. Emphasis is placed on the trends of the dynamical stability and anisotropic behavior related to structural phase transition. Linear as well as cubic thermal expansion component show a different directional dependence as a function of temperature for the investigated polymorphs of the compound. The origin of the difference in the unit cell expansion is found to be related to the distortion of the ThO₈ dodecahedra. The analysis of the non-covalent dispersion of the zircon and scheelite structures reveals a counter-balance between destabilizing interactions due to steric crowding and the current attractive and repulsive ones.     

Layered double hydroxide(LDH)-based materials:A mini-review on strategies to improve the performance for photocatalytic water splitting

The high energy demand we currently face in society and the subsequent large consumption of fossil fuels cause its depletion and increase the pollution levels.The quest for the production of clean energy from renewable and sustainable sources remains open.The conversion of solar energy into hydrogen via the water-splitting process,assisted by pho tores pons ive semiconductor catalysts,is one of the most promising technologies.Significant progress has been made on water splitting in the past few years and a variety of photocatalysts active not only under ultra-violet(UV) light but especially with the visible part of the electromagnetic spectrum have been developed.Layered double hydroxides(LDH)-based materials have emerged as a promising class of nanomaterials for solar energy applications owing to their unique layered structure,compositional flexibility,tunable bandgaps,ease of synthesis and low manufacturing costs.This review covers the most recent research dedicated to LDH materials for photocatalytic water-splitting applications and encompasses a range of synthetic strategies and post-modifications used to enhance their performance.Moreover,we provide a thorough discussion of the experimental conditions crucial to obtaining improved photoactivity and highlight the impact of some specific parameters,namely,catalysts loading,cocatalysts,sacrificial agents,and irradiation sources.This review provides the necessary tools to select the election technique for adequately enhancing the photoactivity of LDH and modified LDH-based materials and concludes with a critical summary that outlines further research directions.     

Quantization of the Sphere with Coherent States

Current views link quantization with dynamics. The reason is that quantum mechanics or quantum field theories address to dynamical systems, i.e., particles or fields. Our point of view here breaks the link between quantization and dynamics: any (classical) physical system can be quantized. Only dynamical systems lead to dynamical quantum theories, which appear to result from the quantization of symplectic structures.     

Scanning electrochemical microscopy for the direct patterning of a gold surface with organic moities derived from iodonium salt

The scanning electrochemical microscope (SECM) is used in the direct mode to draw patterns of a thin passivating organic layer on a gold electrode surface and to image them. The patterning is ensured by the local electrografting of the organic moieties obtained by reduction of an aryliodonium salt, as evidenced by XPS and SECM line scans. The resolution of the writing process is controlled by the charge injected.     

Synthesis of Biologically Active 4-Oxo-4H-Chromene Derivatives Containing Sulfur-Nitrogen Heterocycles

The synthesis of 4-oxo-4H-chromenes containing sulfur-nitrogen heterocyclic rings as well as their biological activities are reviewed.     

A high efficiency 3D photovoltaic microwire with carbon nanotubes (CNT)‐quantum dot (QD) hybrid interface

An innovative hybrid QD sensitized photovoltaic carbon nanotubes microyarn has been developed using thermally‐stable and highly conductive carbon nanotubes yarns (CNYs). These CNYs are highly inter‐aligned, ultrastrong and flexible with excellent electrical conductivity, mechanical integrity and catalytic properties. The CNYs are coated with a QD‐incorporated TiO₂ microfilm and intertwined with a second set of CNYs as a counter electrode (CE). The maximum photon to current conversion efficiency (η_AM1.5) achieved with prolonged‐time stability was 5.93%. These cells are capable of efficiently harvesting incident photons regardless of direction and generating photocurrents with high efficiency and operational stability.

     

Nuclear deformation during breast cancer cell transmigration

Metastasis is the main cause of cancer mortality. During this process, cancer cells dislodge from a primary tumor, enter the circulation and form secondary tumors in distal organs. It is poorly understood how these cells manage to cross the tight syncytium of endothelial cells that lines the capillaries. Such capillary transmigration would require a drastic change in cell shape. We have therefore developed a microfluidic platform to study the transmigration of cancer cells. The device consists of an array of microchannels mimicking the confined spaces encountered. A thin glass coverslip bottom allows high resolution imaging of cell dynamics. We show that nuclear deformation is a critical and rate-limiting step for transmigration of highly metastatic human breast cancer cells. Transmigration was significantly reduced following the treatment with a protein methyltransferase inhibitor, suggesting that chromatin condensation might play an important role. Since transmigration is critical for cancer metastasis, this new platform may be useful for developing improved cancer therapies.