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Second sound is known as the thermal transport regime occurring in a wave-like fashion, usually identified in a limited number of materials only at cryogenic temperatures. Here we show that second sound in a μm-long carbon chain (cumulene) might occur even at room temperature. To this aim, we calibrate a many-body force field on the first principles calculated phonon dispersion relations of cumulene and, through molecular dynamics, we mimic laser-induced transient thermal grating experiments. We provide evidence that by tuning temperature as well as the space modulation of its initial profile we can reversibly drive the system from a wave-like to a diffusive-like thermal transport. By following three different theoretical methodologies (molecular dynamics, the Maxwell-Cattaneo-Vernotte equation, and heat transport microscopic theory) we estimate for cumulene a second sound velocity in the range of 2.4-3.2 km s-1.Selective identification of metal ions as well as their removal is possible when a sensing unit is anchored to a solid support. In this paper, functionalized mesoporous silica with a pendant rhodamine 6G moiety (R6FMS) has been obtained by successive grafting of an aldehyde derivative of bisphenol A followed by rhodamine 6G over a 3-aminopropyl anchored mesoporous silica framework. The materials have been characterized by powder X-ray diffraction, nitrogen sorption and electron microscopy studies, FT-IR and solid state MAS NMR spectral studies, and thermal analysis. In ethanol, the colorless silica material gives pink coloration in the presence of Al3+, Cr3+, Fe3+ and Cu2+ which is also clearly evident from the generation of an absorption peak at 525 nm. Upon excitation at 500 nm, the fluorescence intensity of the probe increases by 36-, 17-, 40- and 89-fold in the presence of Al3+, Cr3+, Fe3+ and Cu2+ ions, respectively. This suggests that R6FMS is a colorimetric and fluorescent chemosensor for these cations in ethanol. However, when the solvent is changed from ethanol to water, it becomes a selective chemosensor only for Cu2+ and Hg2+, by the generation of a pink color and strong fluorescence at ca. 550 nm, thereby discriminating the trivalent cations. Cations induce the opening of the spirolactam ring resulting in pink coloration and strong fluorescence. The quantum yield and lifetime of the probe have been increased considerably in the presence of these cations in ethanol as well as in aqueous media. The detection limit values for these cations range from 10-6 to 10-8 M. R6FMS has been used to remove Hg2+ and Cu2+ from their aqueous solution with a maximum adsorption capacity of 35 mg g-1 and 148 mg g-1 for Cu2+ and Hg2+, respectively.Viscous environments are ubiquitous in nature and in engineering applications, from mucus in lungs to oil recovery strategies in the earth's subsurface - and in all these environments, bacteria also thrive. The behavior of bacteria in viscous environments has been investigated for a single bacterium, but not for active suspensions. Dense populations of pusher-type bacteria are known to create superfluidic regimes where the effective viscosity of the entire suspension is reduced through collective motion, and the main purpose of this study is to investigate how a viscous environment will affect this behavior. Using a Couette rheometer, we measure shear stress as a function of the applied shear rate to define the effective viscosity of suspensions of Escherichia coli (E. coli), while varying both the bacterial density within the suspension and the viscosity of the suspending fluid. We document the remarkable observation that E. coli decreases the effective suspension viscosity to near-zero (superfluidic regime) for all solvent viscosities tested (1-17 mPa s). Specifically, we observe that the bacterial density needed to trigger this superfluidic regime and the maximum shear rate under which this regime can be sustained both decrease with increasing solvent viscosity. We find that the resulting rheograms can be well approximated by the Carreau-Yasuda law. Using this, we propose a constitutive model as a function of the solvent viscosity and the bacterial concentration only. This model captures the onset of the superfluidic regime and offers promising avenues for the modelling of flow of bacterial suspensions in viscous environments.Heterometallic Anderson wheels of formula [(VIVO)2MII5(hmp)10Cl2](ClO4)2·2MeOH (M = Ni, 1; Co, 2) have been synthesised from the solvothermal reaction of M(ClO4)2·6H2O and VCl3 with hmpH (2-(hydroxymethyl)pyridine). The metallic skeleton describes a centred hexagon, with the two vanadyl ions sitting on opposing sides of the outer ring. Magnetic susceptibility and magnetisation measurements indicate the presence of both ferromagnetic and antiferromagnetic exchange interactions. Theoretical calculations based on density functional methods reproduce both the sign and strength of the exchange interactions found experimentally, and rationalise the parameters extracted.Carbon-based single-atom catalysts (SACs) have shown promising applications in the conversion of CO2 into CO. However, the deep reduction process for the production of high-value hydrocarbons is largely limited due to the weak activation of CO. Herein, on the basis of first-principles calculations, a simple coordination regulation method of the active site is proposed to improve the conversion of CO2. Taking NiN4 as an example, by introducing heteroatoms (B, C, O, P, and S atoms), we reveal that NiN3B can effectively capture *CO and further convert to CH4 with an ultralow limiting potential of -0.42 V. The excellent catalytic performance is probably attributed to the formed synergistic dual active sites between non-metal B and metal Ni atoms. see more Moreover, NiN3B can maintain good stability and the catalytic performance can be further enhanced by increasing the B-doping concentration. This work demonstrates that coordination regulation is an effective strategy to improve the performance of single-atom catalysts and paves a possible way to advance the development of non-Cu-based CO2RR electrocatalysts for high-value hydrocarbon products.
Here's my website: https://www.selleckchem.com/products/cftrinh-172.html
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