Laser-muon spin spectroscopy in liquids - a technique to study the excited state chemistry of transients

This study introduces laser-muon spin spectroscopy in the liquid phase, which extends muonium chemistry in liquids to the realm of excited states and enables the detection of muoniated molecules by their spin evolution after laser excitation. This leads to new opportunities to study the Kinetic Isotope Effects (KIEs) of muonium/atomic hydrogen reactions and to probe transient chemistry in radiolysis processes involved in muonium formation, as well as muoniated intermediates in excited states.     

Synthesis, characterization and solid-phase C NMR of naphtho-9-crown-3

The synthesis and characterization of naptho-9-crown-3, N9C3, as a novel 9-membered ring crown ether with greater lipophilicity than that of benzo-9-crown-3, B9C3, is reported. The solution AA′BB′ pattern of –CH₂O– protons in N9C3 is close to that of B9C3. The solid-phase ¹³C CPMAS NMR, as a tool for conformation prediction, reveals that the solid-phase conformation of the 9-membered ring crown cavity in N9C3 is different from B9C3, the two key C2O2CH₂ and C3O1CH₂ units are predicted to be out of naphthalene plane, and the two C1C2O2CH₂ and C4C3O1CH₂ torsion angles are close to each other.     

Modelling investigation on the thermal conductivity of pure liquid,vapour, and supercritical refrigerants and their mixtures by using Heyen EOS

This work presents a literature survey of the available data regarding the thermal conductivity of refrigerants. About 31 pure refrigerants that contain 7127 data points are selected for the temperature range of 91.35–580.00 K, a pressure range of (0.000111-500) bar, and thermal conductivity range of (0.007–0.27) W m^?1 K^?1 containing liquid, vapour, and supercritical phases. Seven binary and three ternary mixtures are also collected both in liquid and vapour phases with an overall of 803 data points. Based on the similarity between the pressure-volume-temperature and Tλ (thermal conductivity) P diagrams, the thermal conductivity model based on Heyen equation of state has been developed for pure refrigerants and their mixtures. The genetic algorithm is used to determine the adjustable parameters of the model. The calculation results prove that this proposed model can reproduce and predict thermal conductivity of refrigerants with good accuracy (overall AAD = 6.85% for pure compounds, AAD = 6.14% for binary mixtures and AAD = 9.32% for ternary mixtures).     

Dynamic drag force based on iterative density mapping: A new numerical tool for three‐dimensional analysis of particle trajectories in a dielectrophoretic system

Dielectrophoresis is a widely used means of manipulating suspended particles within microfluidic systems. In order to efficiently design such systems for a desired application, various numerical methods exist that enable particle trajectory plotting in two or three dimensions based on the interplay of hydrodynamic and dielectrophoretic forces. While various models are described in the literature, few are capable of modeling interactions between particles as well as their surrounding environment as these interactions are complex, multifaceted, and computationally expensive to the point of being prohibitive when considering a large number of particles. In this paper, we present a numerical model designed to enable spatial analysis of the physical effects exerted upon particles within microfluidic systems employing dielectrophoresis. The model presents a means of approximating the effects of the presence of large numbers of particles through dynamically adjusting hydrodynamic drag force based on particle density, thereby introducing a measure of emulated particle–particle and particle–liquid interactions. This model is referred to as “dynamic drag force based on iterative density mapping.” The resultant numerical model is used to simulate and predict particle trajectory and velocity profiles within a microfluidic system incorporating curved dielectrophoretic microelectrodes. The simulated data are compared favorably with experimental data gathered using microparticle image velocimetry, and is contrasted against simulated data generated using traditional “effective moment Stokes‐drag method,” showing more accurate particle velocity profiles for areas of high particle density.     

Sequential one-pot five-component synthesis of tetrazole-based spirotetrahydro-β-carbolines

A one-pot five-component two-step sequential synthesis of tetrazole-based tetrahydrospiro[indene-2,1′-pyrido[3,4-b]indole]-1,3-diones in moderate to good yields is described. The reaction consists of four-component condensation of aromatic aldehydes with tryptamine, trimethylsilyl azide (TMSN₃) and isocyanides, followed by addition of ninhydrin. These reactions presumably proceeded through Ugi-azide/Pictet–Spengler processes, respectively.     

Synthesis of novel tetra- and pentacyclic benzosultam scaffolds via domino Knoevenagel hetero-Diels–Alder reactions in water

An efficient catalyst-free and diastereoselective synthesis of novel dihydropyrano[2,3-d]pyrimidine and dihydropyrano[3,2-c]chromen-annulated benzosultams is described. A number of (E)-N-(2-formylphenyl)-N-methyl-2-phenylethenesulfonamides were synthesized and underwent a one-pot domino Knoevenagel hetero-Diels–Alder reaction, respectively, with N,N-dimethylbarbituric acid and 4-hydroxycoumarin in water, giving the desired products, in moderate to excellent yields.