Zobrazení zdroje stránky Pickettlindgreen1233

This work fundamentally investigates how the second harmonic generation (SHG) from commercial nonlinear crystals can be boosted by the addition of individual optical nanoantennas. Frequency conversion plays an important role in modern non-linear optics, and nonlinear crystals have become a widely used building block for non-linear processes. Still, SHG remains hampered by limited conversion efficiency. To strengthen SHG from the crystal surface, we investigate the interaction of LiNbO3 crystals with individual gold nanodiscs. The scattered intensities and resonance frequencies of the nanodiscs are analyzed by dark-field spectroscopy and simulations. Subsequently, the discs on LiNbO3 are excited by a pulsed femtosecond laser in a parabolic mirror setup. Comparing the SHG at the position of a single nanodisc at resonance on the crystal with that of the unstructured crystal and of gold nanodiscs on a reference substrate, local SHG enhancement of up to a factor of three was achieved in the focal volume through the presence of the antenna.In molecular dynamics (MD) simulations of condensed-phase systems, straight-cutoff truncation of the non-bonded interactions is well known to cause cutoff noise and serious artifacts in many simulated properties. These effects can be drastically reduced by applying the truncation based on distances between neutral charge groups (CG) rather than between individual atoms (AT). In addition, the mean effect of the omitted electrostatic interactions beyond the cutoff distance can be reintroduced using the reaction-field (RF) method, where the medium outside the cutoff sphere is approximated as a dielectric continuum of permittivity equal to that of the solvent. [https://www.selleckchem.com/products/polyinosinic-acid-polycytidylic-acid.html find more] The RF scheme is generally applied with CG truncation. This is justified for low solvent permittivities, where the RF correction is small and an AT truncation would lead to severe issues, just as in the straight-cutoff case. However, it is less appropriate for solvents with high permittivities, where the RF correction acts as a physically motivated shiftings.Hypsampsone A (1) and hyperhexanone F (2), two novel seco-polycyclic polyprenylated acylphloroglucinols, were isolated from Hypericum sampsonii. Hypsampsone A (1) features the first spirocyclic system fused with 5/6/5/5 tetracyclic skeleton. Hyperhexanone F (2) represents the second novel 1,2-seco-bicyclo[3.3.1]-PPAP skeleton. Their structures were established by extensive spectroscopic analysis, computer-assisted structure elucidation software, and calculated electronic circular dichroism spectra. A plausible biogenetic pathway of 1 was also proposed. Compounds 1 and 2 showed moderate multidrug resistance reversal activity to adriamycin (ADR) resistant cancer cell lines, HepG2/ADR and MCF-7/ADR, with the fold-reversals ranging from 16 to 38 at noncytotoxic concentration of 10 μM.In this paper, electrophoretic deposition (EPD) is shown to promote nanoscale assembling of graphene oxide (GO) enabling the fabrication of highly homogeneous, robust, and capacity fade resistant composite titanium niobate (TiNb2O7, TNO)/rGO anodes upon reductive annealing. Control tests revealed that EPD is superior to conventional PVDF-based casting in maximizing the performance benefits from using reduced GO in Li-ion electrode fabrication as is the case of TNO that is plagued with conductivity and capacity fading problems. In this particular study, we show that there is a synergy developed between GO and EPD with the former (1) stabilizing the EPD suspension, (2) acting as a flexible binder net that affords mechanical integrity during the volume expansion of TNO, (3) serving as a conductive filler, and (4) contributing to Li-ion storage via pseudocapacitance. As a consequence, a superior percolation network is developed. Thus while both EPD- and PVDF- built TNO/rGO composite anodes exhibited high initial capacities (∼350 and 318 mA h g-1) at 0.5 C cycling, respectively, their cycling behaviour was quite different with the latter experiencing high internal polarization and extended degradation. Post-mortem PEEM-XANES analysis clearly demonstrated a highly homogeneous mesostructure in the case of the EPD-built TNO/rGO anode vs. a highly segregated and dis-jointed rGO and TNO component clustering in the PVDF-built electrode.Numerous types of diseases cause serious anemia, which is characterized by a significantly decreased number of circulating red blood cells. The key reason is retarded terminal erythroid differentiation, which is largely involved in the downregulation of intracellular reactive oxygen species (ROS) and insufficient iron uptake. Prussian blue nanoparticles (PBNPs) have been demonstrated to be capable of scavenging ROS via multienzyme-like activity and contain the iron element. The aim of this study was to figure out whether PBNPs can induce terminal erythroid differentiation in myeloid leukemia cells K562 and to investigate the underlying mechanisms. Our results showed that PBNPs were taken up by K562 cells, which reduced the intracellular ROS level in the cells, upregulated the late erythroid surface marker GYPA (CD235a) and downregulated the early erythroid surface marker TFRC (CD71), clearly indicating the occurrence of terminal erythroid differentiation. In addition, the cells became smaller in size after incubation with PBNPs, providing strong side evidence that the cells had undergone terminal differentiation. Mechanistic studies indicated that PBNP-induced terminal differentiation was associated with the upregulation of the nuclear transcriptional factor NFE2 and downregulation of GATA1, both of which are closely related to the variation of intracellular ROS levels. In conclusion, PBNPs demonstrated a novel function by effectively inducing terminal erythroid differentiation in myeloid leukemia cells, which is of great significance in improving the blood profiles of anemia patients.A visible-light-promoted S-H insertion reaction between thiols and α-diazoesters was developed. The reaction proceeded smoothly at room temperature with a broad substrate scope, affording various thioethers in moderate to excellent yields. The catalyst- and additive-free nature, sustainable energy source and mild reaction conditions make this strategy more eco-friendly.Taking advantage of the base-pairing specificity and tunability of DNA interactions, we investigate the spontaneous formation of hyperbranched clusters starting from purposely designed DNA tetravalent nanostar monomers, encoding in their four sticky ends the desired binding rules. Specifically, we combine molecular dynamics simulations and Dynamic Light Scattering experiments to follow the aggregation process of DNA nanostars at different concentrations and temperatures. At odds with the Flory-Stockmayer predictions, we find that, even when all possible bonds are formed, the system does not reach percolation due to the presence of intracluster bonds. We present an extension of the Flory-Stockmayer theory that properly describes the numerical and experimental results.A series of bimetallic ruthenium vinyl complexes 1-5 bridged by oligoacenes were synthesized and characterized in this study. Comparative cyclic voltammetry results from 1-5 indicated that the first oxidation potential decreased gradually with the extension of conjugate ligands. Upon oxidation to singly oxidized species 1+-5+, rather small ν(CO) changes in the infrared (IR) spectra and the characteristic bands of metal-to-ligand charge transfer absorptions in the near IR (NIR) region predicted via time-dependent DFT calculations suggested that strong bridged ligands participate in redox processes. NIR absorptions were not observed in complexes 4+ and 5+ possibly because of instability in their twisted and noncoplanar geometry. Electron paramagnetic resonance results and spin density distribution demonstrated that the bridged localized degrees of 1+-5+ successively increased with the extension of oligoacene from benzene to tetracene. Further comparative analysis of neutral molecules and monocations to the aromaticity and π-electron density of bridge cores indicated a step-by-step transformation process from an aromatic to quinoidal radical upon oxidation.This paper describes a tetrahedral mononuclear Co(ii) complex [CoL2](ClO4)2 (1) in which L = 2,9-diphenyl-1,10-phenanthroline. The structure of 1, which was determined by single crystal X-ray diffraction, indicates that it exists in the triclinic space group P1[combining macron]. Magnetic property studies were conducted by reduced magnetization measurements, ab initio calculations and X-band EPR experiments, the results of which revealed a large zero-field splitting, with D ∼ -45.9 cm-1. The Arrhenius equation indicates that the kinetic energy barrier of 1 is Ueff = 46.9 cm-1. This study describes a very rare case of a Co(ii) single ion magnet (SIM) that is purely tetrahedrally coordinated by pyridine like ligands.Layered transition-metal compounds with controllable magnetic behaviors provide many fascinating opportunities for the fabrication of high-performance magneto-electric and spintronic devices. The tuning of their electronic and magnetic properties is usually limited to the change of layer thickness, electrostatic doping, and the control of electric and magnetic fields. However, pressure has been rarely exploited as a control parameter for tailoring their magneto-electric properties. Here, we report a unique pressure-driven isostructural phase transition in layered CrCl3 accompanied by a simultaneous switching of magnetism from a ferromagnetic to an antiferromagnetic ordering. Our experiments, in combination with ab initio calculations, demonstrate that such a magnetic transition hinders the bandgap collapse under pressure, leading to an anomalous semiconductor-to-semiconductor transition. Our findings not only reveal the potential applications of this material in electronic and spintronic devices but also establish the basis for exploring unusual phase transitions in layered transition-metal compounds.We present here the results of low-temperature magnetization and X-ray magnetic circular dichroism studies on the single crystals of BaFe12O19 which reveal for the first time the emergence of a spin glass phase, in coexistence with a long-range ordered ferrimagnetic phase, due to the freezing of the basal plane spin component.Sensitive detection of copper ions (Cu2+) in biological samples is extremely important since an abnormal level of Cu2+ is linked with many diseases. Herein, we demonstrated a novel turn-on colorimetric sensor for selective detection of Cu2+ both in buffered solution and serum samples based on porous bimetallic transition metal oxide nanocages (ZnO-Co3O4 NCs) as peroxidase mimics. The ZnO-Co3O4 NCs were prepared by using ZnCo-zeolitic-imidazolate-framework (ZnCo-ZIF) as precursors via direct calcination. With the high peroxidase-like activity, the obtained ZnO-Co3O4 NCs can catalyze the oxidation of tetramethylbenzidine (TMB) in the presence of H2O2 to form a blue colored product. The inhibition effect of cysteine (Cys) on the catalytic activity of ZnO-Co3O4 NCs and its strong binding ability toward Cu2+ enabled the ZnO-Co3O4 NCs/Cys system to be utilized for sensitive detection of Cu2+, in which the catalytic activity of ZnO-Co3O4 NCs/Cys can be recovered by the introduction of Cu2+ with an obvious color change of the solution.