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Hydrogen production from the decomposition of ammonia is considered an effective approach for addressing challenges associated with hydrogen storage and transportation. However, their relatively high energy consumption and low efficiency hinder practical multi‐scenario applications. In this study, Y2O3‐stabilized catalysts with Co‐loaded onto porous nitrogen‐doped carbon (Y2O3–Co/NC) are synthesized by pyrolysis of Y(NO3)3‐modified ZIF‐67 under an inert atmosphere, followed by annealing in a reducing environment. The introduction of Y2O3 enhanced the recombination and desorption of N atoms and facilitated the gradual dehydrogenation of NHx on the catalyst surface, resulting in improved catalytic activity for the thermal decomposition of ammonia. Benefitting from the electron‐donating properties of Y2O3 and N‐doped carbon, the optimized catalyst achieved a remarkable NH3 conversion efficiency of 92.3% at a high gas hourly space velocity of 20 000 cm3·gcat−1${\mathrm{g}}_{{\mathrm{cat}}}^{ - {\mathrm{1}}}$·h−1 with an encouraging H2 production rate of 20.6 mmol·gcat−1${\mathrm{g}}_{{\mathrm{cat}}}^{ - {\mathrm{1}}}$·min−1 at 550 °C. Moreover, the synthesized catalyst undergoes a fast‐dynamic reconstruction process, resulting in exceptionally stable catalytic activity during the thermal decomposition of ammonia, rendering it a promising candidate for carbon‐free energy thermocatalytic conversion technology. [ABSTRACT FROM AUTHOR]

Let 퐺 be a finite group, k ⁢ (G) the number of conjugacy classes of 퐺, and 퐵 a nilpotent subgroup of 퐺. In this paper, we prove that | B ⁢ O π ⁢ (G) / O π ⁢ (G) | ≤ | G | / k ⁢ (G) if 퐺 is solvable and that 15 7 ⁢ | B ⁢ O π ⁢ (G) / O π ⁢ (G) | ≤ | G | / k ⁢ (G) if 퐺 is nonsolvable, where π = π ⁢ (B) is the set of prime divisors of | B | . Both bounds are best possible. [ABSTRACT FROM AUTHOR]

A new amphiphilic boron-dipyrromethene (BODIPY) dye bearing a hydrophobic 2,3,4-tris(n-dodecyloxy) phenyl group at the meso-position and two hydrophilic cationic moieties at the boron was synthesized. This dye exhibited kinetically controlled and thermodynamically controlled aggregation pathways in aqueous solution, leading to the formation of two types of J-aggregates, i.e., the metastable Agg. I and thermodynamically more stable Agg. II. Further kinetic analysis of the spontaneous transformation from Agg. I to Agg. II indicated that Agg. I was an off-pathway aggregate species. Moreover, both Agg. I and Agg. II displayed J-aggregate characteristics with enhanced fluorescence quantum yields and shortened fluorescence lifetime with respect to that of the monomeric dye. In particular, Agg. II exhibited a narrowed and intense J-band, reflecting the strong excitonic coherence in the aggregate. Morphological studies revealed that Agg. I consisted of spherical nanoparticles, while Agg. II had a multilamellar vesicular structure. In addition, in the fluorescence spectra of Agg. I and Agg. II, an unexpected broad band at longer wavelength than that of the J-aggregate emission was observed, which could be ascribed to the possible formation of excimers in these J-aggregates in aqueous solution. [ABSTRACT FROM AUTHOR]

An amphiphilic aza‐BODIPY dye (S)‐1 bearing two chiral hydrophilic side chains with S‐stereogenic centers was synthesized. This dye exhibited kinetic‐controlled self‐assembly pathways and supramolecular chiral polymorphism properties in MeOH/H2O (9/1, v/v) mixed solvent. The (S)‐1 monomers first aggregated into a kinetic controlled, off‐pathway species Agg. A, which was spontaneously transformed into an on‐pathway metastable aggregate (Agg. B) and subsequently into the thermodynamic Agg. C. The three aggregate polymorphs of dye (S)‐1 displayed distinct optical properties and nanomorphologies. In particular, chiral J‐aggregation characteristics were observed for both Agg. B and Agg. C, such as Davydov‐split absorption bands (Agg. B), extremely sharp and intense J‐band with large bathochromic shift (Agg. C), non‐diminished fluorescence upon aggregation, as well as strong bisignated Cotton effects. Moreover, the AFM and TEM studies revealed that Agg. A had the morphology of nanoparticle while fibril or rod‐like helical nanostructures with left‐handedness were observed respectively for Agg. B and Agg. C. By controlling the kinetic transformation process from Agg. B to Agg. C, thin films consisting of Agg. B and Agg. C with different ratios were prepared, which displayed tunable CPL with emission maxima at 788–805 nm and g‐factors between −4.2×10−2 and −5.1×10−2. [ABSTRACT FROM AUTHOR]

Let G be a π -solvable group for some set of primes π. We show that if H is a Hall π -subgroup of G , then | H / O π (G) | ≤ | G | / k (G) , where k (G) is the number of conjugacy classes of G. [ABSTRACT FROM AUTHOR]

In this article, we study extensions of conformal modules over Lie conformal algebras W (a , b , r) with three parameters a, b, r ∈ C , which contain the Virasoro Lie conformal algebra Vir, W (b) and W (a , b) as subalgebras. We obtain the existence conditions of extensions of nontrivial conformal modules over W (a , b , r) and give a complete classification of extensions of finite irreducible conformal modules of W (a , b , r) . [ABSTRACT FROM AUTHOR]