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Themetastable equilibrium solubilities and the physicochemicalproperties including refractive index, density, viscosity, conductivity,and pH for the aqueous reciprocal five-component system (Li + Na +K + Cl + SO4+ H2O) at 308.15 K were studiedusing the isothermal evaporation method. According to the experimentaldata, the dry-salt-phase diagram, sodium-phase diagram, water-phasediagram, and the diagrams of physicochemical properties versus compositionwere plotted. The dry-salt-phase diagram of the five-component systemincludes seven four-salt cosaturated points, fourteen univariant solubilitycurves, and eight crystallization zones all saturated with sodiumchloride. Three kinds of double salts of lithium salts (Db1, Li2SO4·3Na2SO4·12H2O; Db2, Li2SO4·Na2SO4; Db3, 2Li2SO4·Na2SO4·K2SO4) were found, and no solidsolution was formed in the metastable five-component system. Becausethe Pitzer mixing ion-interaction parameters containing lithium andsodium such as θLi,Na, ΨLi,Na,Cl, and ΨLi,Na,SO4at 308.15 K are scarce,the solubilities of the five-component system at 298.15 K were calculatedon the basis of Pitzer’s ion-interaction theory and the chemicalequilibrium Harvie–Møller–Weare model (HMW model).A comparison of the calculated phase diagram at 298.15 K and the experimentalphase diagram at 308.15 K was also carried out. [ABSTRACT FROM AUTHOR]

Thesolubility and density of the thermodynamic phase equilibriaternary system (Na2SO4+ Li2SO4+ H2O) at (288 and 308) K were determined usingthe isothermal dissolution method. According to the experimental resultsof the ternary system at (288 and 308) K, the phase diagrams and thediagrams of density versus composition were plotted. In the ternarysystem at 308 K, four crystallization regions corresponding to thenardite(Na2SO4, Th), two congruent double salts ofLi2SO4·3Na2SO4·12H2O (Db1) and Li2SO4·Na2SO4(Db2), and lithium sulfate monohydrate (Li2SO4·H2O, Ls) were found, whereas onlythree crystallization regions corresponding to Ls, one incongruentdouble salt of Db1, and mirabilite (Na2SO4·10H2O, Mir) were found in the system at 288 K. No solid solutionwas found at either temperature. When the experimental phase diagramat 308 K was compared with that at 288 K, it shows that (1) a newphase region of double salt Db2 was formed and the mineral of Mirtransformed into Th with the increase of temperature from (288 to308) K and (2) the area of the crystallization region of sodium sulfatewas decreased sharply and those of the crystallized regions of Li2SO4·H2O and double salt Db1 increasedobviously. The solution densities of the ternary system both at (288and 308) K change regularly with increasing lithium sulfate concentrationin solution. Based on the Pitzer model and its extended Harvie-Weare(HW) model, the mixing triple interaction parameter of ΨLi,Na,SO4at (288 and 308) K and the solubility equilibriumconstants Kspof solid phases Ls, Db1,Db2, Th, and Mir at (288 and 308) K, which are not reported in theliterature, were acquired by fitting the experimental solubility dataof the ternary system (Li2SO4+ Na2SO4+ H2O) by the lease-square method. A comparisonbetween the calculated and experimental results at (288 and 308) Kfor the ternary system shows that the predicted solubilities obtainedwith the extended HW model agree well with experimental data. [ABSTRACT FROM AUTHOR]

Experimental studies on the metastable solubilities and physicochemical properties (density, viscosity, pH, and refractive index) of the aqueous quaternary system (NaCl + MgCl2+ Na2SO4+ MgSO4+ H2O) at 323.15 K were determined with the method of isothermal evaporation. On the basis of experimental data, the metastable phase diagram and the diagram of physicochemical properties versus composition were plotted. There are six invariant points, twelve univariant curves, and seven crystallization zones corresponding to halite, thenardite, vanthoffite (3NaSO4·MgSO4), astrakanite (NaSO4·MgSO4·4H2O), hexahydrite (MgSO4·6H2O), tetrahydrite (MgSO4·4H2O), and bischofite (MgCl2·6H2O). There is no solid solution except two double salts of vanthoffite and astrakanite which existed in the metastable system. When compared with the stable equilibrium phase diagram at 328.15 K, the crystallized zones of loeweite (6Na2SO4·7MgSO4·15H2O) and kieserite (MgSO4·H2O) disappeared; the areas of halite and hexahydrite increased; and the areas of thenardite, astrakanite, and vanthoffite decreased. It is indicated that the metastable phenomena of sodium sulfate and magnesium sulfate are significant. The physicochemical properties (density, viscosity, pH, and refractive index) in the metastable equilibrium system change regularly with the mass fraction change of the magnesium ion. [ABSTRACT FROM AUTHOR]

The catalytic asymmetric conjugate addition of phosphorus nucleophiles to unsaturated compounds, catalyzed by metallic or nonmetallic catalysts, has been extensively developed. However, the enantioselective transformations involving α,β-unsaturated carboxylic esters for constructing chiral c-p bonds have been rarely reported, particularly in metal-free processes. In this study, we present a novel metal-free methodology for enantioselective 1,4-addition of diarylphosphine oxides to α,β-unsaturated carboxylic esters using classical chiral oxazaborolidine catalysts. Remarkably high yields and enantioselectivities were obtained for most of the products. Furthermore, these valuable chiral phosphorus esters serve as crucial intermediates that can be transformed into various derivatives including amides, acids, and alcohols in a single step.

Electrochemical CO 2 reduction enables the conversion of intermittent renewable energy to value-added chemicals and fuel, presenting a promising strategy to relieve CO 2 emission and achieve clean energy storage. In this work, we developed nanosized Cu 2 O catalysts using the hydrothermal method for electrochemical CO 2 reduction to alcohols. Cu 2 O nanoparticles (NPs) of various morphologies that were enclosed with different crystal facets, named as Cu 2 O-c (cubic structure with (100) facets), Cu 2 O-o (octahedron structure with (111) facets), Cu 2 O-t (truncated octahedron structure with both (100) and (111) facets), and Cu 2 O-u (urchin-like structure with (100), (220), and (222) facets), were prepared by regulating the content of a polyvinyl pyrrolidone (PVP) template. The electrochemical CO 2 reduction performance of the different Cu 2 O NPs was evaluated in the CO 2 -saturated 0.5 M KHCO 3 electrolyte. The as-synthesized Cu 2 O nanostructures were capable of reducing CO 2 to produce alcohols including methanol, ethanol, and isopropanol. The alcohol selectivity of the different Cu 2 O NPs followed the order of Cu 2 O-t < Cu 2 O-u < Cu 2 O-c < Cu 2 O-o (with the total Faradaic efficiencies of alcohol products of 10.7, 25.0, 26.2, and 35.4%). The facet-dependent effects were associated with the varied concentrations of oxygen-vacancy defects, different energy barriers of CO 2 reduction, and distinct Cu-O bond lengths over the different crystal facets. The desired Cu 2 O-o catalyst exhibited good reduction activity with the highest partial current density of 0.51 mA/cm 2 for alcohols. The Faradaic efficiencies of alcohol products were 4.9% for methanol, 17.9% for ethanol, and 12.6% for isopropanol. The good electrochemical CO 2 reduction performance was also associated with the surface reconstruction of Cu 2 O, which endowed the catalyst with abundant Cu 0 and Cu + sites for promoted CO 2 activation and stabilized CO* adsorption for enhanced C-C coupling. This work will provide a new route for enhancing the alcohol selectivity of nanostructured Cu 2 O catalysts by crystal facet engineering.

The key challenge of developing reaction-based turn-on probes is to establish latent electrophilic fluorophores exhibiting high reactivity only upon binding to a specific protein(s). Herein, we identified such a fluorophore, 6-arylthioether-substituted 3-cyano-1-oxo-1 H -phenalene-2-carboxylate, which chemoselectively labels binding site Cys or Lys residues. Based on this fluorophore, we developed the first reaction-based turn-on pyruvate kinase M2 isoform (PKM2) fluorescent probe AT-OPC1 , which selectively labels PKM2 with the binding site Lys305. The latent electrophilic reactivity of the fluorophore endows the probe with precise detection of the expression of PKM2 in situ by means of both in-gel fluorescence imaging at the proteome level and real-time no-wash cell imaging approaches, which has the potential to be applied in cancer diagnoses.

We describe a general catalytic methodology for the enantioselective dearomative alkylation of pyridine derivatives with Grignard reagents, allowing direct access to nearly enantiopure chiral dihydro-4-pyridones with yields up to 98%. The methodology involves dearomatization of in situ-formed N -acylpyridinium salts, employing alkyl organomagnesium reagents as nucleophiles and a chiral copper (I) complex as the catalyst. Computational and mechanistic studies provide insights into the origin of the reactivity and enantioselectivity of the catalytic process., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The concentration of B(OH) 3 , B(OH) 4 - , B 3 O 3 (OH) 4 - , and B 4 O 5 (OH) 4 2- in the solution and the solubilities in the system KCl-K 2 SO 4 -K 2 B 4 O 7 -H 2 O and its subsystems were calculated on the basis of the Pitzer model. The mole fraction of the four boron species is mainly affected by m (B) in the solution but less by m (Cl - ) and m (SO 4 2- ). m (Cl - ) and m (SO 4 2- ) mainly affect the solubility of K 2 B 4 O 5 (OH) 4 ·2H 2 O. The calculated solubilities in the system KCl-K 2 B 4 O 7 -H 2 O agree well with the experimental data. The results show that the standard chemical potentials of K 2 B 4 O 5 (OH) 4 ·2H 2 O at 298.15 K obtained in this work is reliable. The transformation between the boron species at 298.15 K was also conducted with the density functional theory (DFT) method. The results affirm that the boron species can transform other boron species as the boron concentration in the solution changes., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

This study aimed to investigate the effect of arginine on the expression of slow myosin heavy chain (MyHC) I and its underlying mechanism in porcine skeletal muscle satellite cells. Our results showed that arginine upregulated the mRNA (1.54 ± 0.08; p < 0.01) and protein (2.01 ± 0.01; p < 0.001) levels of MyHC I. We also showed that arginine upregulated the expression of Akirin2 (1.35 ± 0.1; p < 0.05) and increased the NO content (1.56 ± 0.04; p < 0.001). Akirin2 siRNA abolished arginine-induced upregulation of MyHC I and the increase of the NO content. In addition, arginine significantly increased the phospho-AMP-activated protein kinase (AMPK)/AMPK level (1.33 ± 0.06; p < 0.05), the AMPK content (79.55 ± 0.13; p < 0.001), and the AMPKα2 mRNA level (2.03 ± 0.20; p < 0.01). AMPKα2 silencing or AMPK inhibitor Compound C abolished arginine-induced upregulation of MyHC I. Our results provide, for the first time, evidence for the involvement of Akirin2 and the AMPK signaling pathway in arginine-induced MyHC I expression in porcine skeletal muscle satellite cells.