Polyaromatic heterocycles through intramolecular alkyne carbonyl metathesis: 5-Acylnaphtho[2,1-b]benzofurans

A modular approach to 5-acylated naphtho[2,1-b]benzofurans was developed where Sonogashira cross-coupling and intramolecular alkyne carbonyl metathesis were sequentially employed to build the aromatic benzene C ring of naphtho[2,1-b]benzofuran with an acyl group at the C5 position.     

Turn-on fluorometric NADPH assay using orange emitting graphene oxide quantum dots

The authors describe a method for synthesizing graphene oxide quantum dots (GOQDs) possessing orange fluorescence with emission wavelength that can be tuned over the range from 537 to 593 nm by variation of the excitation wavelength. The GOQD display peroxidase-mimicking catalytic activity. Specifically, they catalyze the oxidation of dopamine to produce 4-(2-aminoethyl)benzene-1,2-quinone (AQ) which is colored and can quench the fluorescence of GOQDs. However, quenching is reversed by addition of NADP⁺, but not by its reduced form (NADPH). Based on these findings, an assay was worked out to monitor enzymatic reactions involving NADP⁺. The method allows NADPH to be detected in the 2–175 μM concentration range, with a 0.6 μM detection limit.

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Graphical abstract Schematic of a top-down method for synthesizing fluorescent graphene oxide quantum dots (GOQD) by chemical degrading, exfoliation and self-assembly of graphene oxide (GO). The GOQDs display peroxidase-like activity and can oxidize dopamine to form a colored quinone that quenches the fluorescence of the GOQDs. The quenching efficiency is reduced, however, in the presence of NADP⁺.

     

Synthesis of a Novel Double Salt: Ammonium 3,4‐Diamino‐1,2,4‐triazolium Styphnate

Nitrogen‐rich double salt ammonium 3,4‐diamino‐1,2,4‐triazoliumstyphnate (NH₄ · DATr · TNR) ( 2 ) with good thermal stability was successfully synthesized by reacting 3,4‐diamino‐1,2,4‐triazolium chloride aqueous solution with styphnic acid methanol solution under the reaction medium of aqueous ammonia. The title double salt was characterized by elemental analysis (EA), Fourier transformation infrared spectrum (FT‐IR), and X‐ray single‐crystal diffraction. It crystallizes in the monoclinic crystal system with space group P2₁/n. Its density is 1.780 g · cm^–3. Compound 2 is thermal stable below 200 °C by the differential scanning calorimetry (DSC) test. The non‐isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa‐Doyle's method, respectively. In addition, compound 2 showed low friction and impact sensitivities.     

Halocyclization of 2-allyl(propargyl)sulfanyl-6-aminopyrimidin-4(3H)-ones

Russian Journal of Organic Chemistry - The alkylation of 6-amino-2-thiouracil with allyl, methallyl, and propargyl halides in the presence of bases gave 2-[allyl(methallyl,...     

Adsorption and separation behavior of strontium and yttrium using a silica-based bis(2-ethylhexyl) hydrogen phosphate adsorbent

Journal of Radioanalytical and Nuclear Chemistry - (HDEHP?+?Hexa)/SiO2-P, a silica-based adsorbent, was prepared and used to separate Y(III) from a mixed solution of Sr(II) and Y(III)....     

Inclusion of thymol into cucurbiturils: density functional theory approach with dispersion correction and natural bond orbital analysis

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Stability of inclusion complexes of thymol (a natural flavour) with cucurbit[n]urils was interpreted by using density functional theory...     

An analysis on effect of transverse convex curvature on turbulent flow and heat transfer

An analysis based on a model of modified mixing length by Hornby, Mistry und Barrow [1] was made on the effect of transverse convex curvature in turbulent boundary layer for incompressible axial flows along circular cylinders. The deviation of various turbulent flow and heat transfer properties from those of flat plates is presented. The agreement between the analyses and the experimental results for skin friction and heat transfer rate is good. The study demonstrated that, for a given condition, both the friction coefficient and Stanton number increase with decreasing value of the cyclinder radius and that their values are always greater than those for the flow over a flat plate.     

Méthodes d'approximation et d'itération pour les opérateurs monotones

Sans résumé Mémoire présenté par J. L. Lions     

The Hall effect in an electrically conducting fluid for variable magnetic field and high magnetic Reynolds numbers

Hall phenomena in an electrically conducting fluid with a variable magnetic field were considered in [1]. In that paper the basic characteristics of the above-mentioned phenomena are determined, with certain unimportant constraints, for the case of fluid motion along a channel of rectangular cross section in a traveling magnetic field. The magnetic Reynolds number was assumed to be small, and a solution was given for the induction field in the form of a series in powers of the indicated parameter. Quantitative estimates based on the data of [1] are impossible in the case of relatively high electrical conductivity of the fluid, although certain conclusions of a qualitative nature remain valid. There is thus reason to consider the case of high magnetic Reynolds numbers. This will also allow a fuller picture of the characteristic Hall effect phenomena to be constructed for a variable magnetic field.