Search

This investigation explores the microwave dielectric characteristics of BaCa13Mg2(SiO4)8 ceramics, synthesized through conventional solid-state techniques. Via X-ray diffraction analysis and comprehensive data refinement across various temperatures, we unequivocally determined the orthorhombic crystal structure of the BaCa13Mg2(SiO4)8 ceramics. The measured lattice parameters at a sintering temperature of 1345 °C are a = 18.51543 Å, b = 6.77482 Å, and c = 10.95537 Å, with a corresponding unit volume of V = 1374.226706 Å3. The microstructure of the ceramic grains was studied in detail by scanning electron microscopy (SEM), and it was found that the optimum relative density was 97.2%. The study further explored the effects of porosity, packing fraction, relative density, and the impact of Si–O bond valence (VSi-O) on the microwave dielectric characteristics of BaCa13Mg2(SiO4)8 ceramics. Remarkably, the BaCa13Mg2(SiO4)8 ceramics exhibited exceptional performance metrics (εr = 11.53, Q × f = 15,231 GHz (f = 10.6 GHz), τf = − 27.3 ppm/°C) at 1345 °C, establishing it as a promising candidate for microwave applications. [ABSTRACT FROM AUTHOR]

In this work, a silicate ceramic, CaY2Al4SiO12 (CYASO), with a low dielectric constant and low loss was prepared using traditional solid-state methods. X-ray diffraction (XRD) refinement analysis shows that the CYASO material crystallized into a phase with an Ia-3d space group and an impurity peak. The orthogonal cubic structure of the CYASO ceramic was confirmed through transmission electron microscopy (TEM), and the structure exhibited an orderly layered arrangement. The internal microstructure was characterized using scanning electron microscopy (SEM), which showed that the sample's relative density reached 97.8%. We discuss the correlation between the full width at half maximum (FWHM) of the Raman matrix corresponding to the vibration mode of the symmetric bending mode of AlO4 at the Raman shift of 855 cm−1 and the Q × f value. Additionally, the analysis focused on the various factors that influence the dielectric constant, including density, secondary phase, and porosity changes. The ceramics exhibited remarkable microwave dielectric properties (εr = 8.7, Q × f = 34,700 GHz, τf = −35 ppm/°C) when calcined at 1425°C. CYASO ceramic shows great capacity as a microwave dielectric material. [ABSTRACT FROM AUTHOR]

The discovery of overcounting in Orkhon Inscriptions has been an important contribution by historical comparative linguistics during the nineteenth century. However, the initial interpretation of overcounted numerals in Orkhon Inscriptions by Thomsen and Radloff was not correct, resulting in serious difficulties in reconstructing old Turkic history. It was Bang and Marquart who worked out the true semantics of overcounted numerals. This article aims to present a historical overview on the discovery and interpretation of overcounted numerals in Orkhon Inscriptions. Considering that Bang and Marquart did not explicitly spell out their evidence for reaching the true semantics of these numerals, this article presents a series of arguments proving the existence of overcounting in Old Turkic based on language per se, historical facts, logical reasoning, and bilingual translation. [ABSTRACT FROM AUTHOR]

To obtain dual active near-infrared (NIR) nanomaterial with strong absorption and emission properties, we report herein a novel precursor reactivity differentiation strategy, i.e., utilizing 1-octadecene (ODE)-Se having the ability to react with Ag salts much stronger and faster than ODE-thiourea, for single-step preparation of Ag2Se@Ag2S nanocrystals (NCs). With this strategy, we were able to synthesize high-quality Ag2Se@Ag2S NCs with both excellent NIR absorption and emission properties. Particularly, these nanocrystals possess a rather strong and sharp excitonic absorption peak with a full width at half maximum less than 70 nm and a maximum fluorescence quantum yield as high as 24.3%. Their appealing optical properties and structural features were founded to be highly dependent on the Se to S precursor ratio in the reaction solutions, owing to such a ratio exerting a direct influence on the core sizes and shell thicknesses of the as-formed NCs. Taking advantage of their remarkable NIR absorption properties, self-powered photoelectrochemical-type photodetectors based on the as-prepared Ag2Se@Ag2S NCs were successfully fabricated, which demonstrate a much better response performance and photostability in comparison with those based on Ag2Se NCs. [ABSTRACT FROM AUTHOR]

Focuses on translating brand names from Chinese to English. Importance of names to businesses; Four approaches in the Chinese way of translation of brand names; Reason the literal translation method is better than the Pinyin approach; Advantages of the transliteration method; Characteristics of a translators; Criteria for assessing a translated brand name.

Thickness regulation of transition metal hydroxides/oxides nanosheets with superior catalytic properties represents a promising strategy to enhance catalytic performance, but it remains an enormous challenge to achieve precise control, especially when it comes to the ultrathin limit (several atomic layers). In this work, a facile strategy of alkylamine-confined growth is proposed for the synthesis of thickness-tunable metal hydroxide/oxide nanosheets. Specifically, ultrathin cobalt hydroxide and cobaltous oxide hybrid (Co(OH) 2 -CoO) nanosheets (Co-O NSs) with a thickness in the range of 2-6 nm (5-13 atomic layers) are synthesized by using alkylamines with different carbon chain lengths as the ligand to modulate vertical coordination ability. Co-O NSs with a thickness of 2 nm (Co-O NSs-2 nm) exhibit excellent oxygen evolution reaction (OER) performance with an overpotential of 278 mV at 10 mA/cm 2 . The maximized number of active sites including oxygen vacancies, optimal adsorption strength, and the highest electrical conductivity are considered as the potential factors contributing to the excellent OER performance of Co-O NSs-2 nm. This work holds great significance for the precise thickness-tunable synthesis of transition metal layered hydroxide nanosheets with modulated and improved catalytic performance.

This study describes a facile and effective route to synthesize hybrid material consisting of Co 3 O 4 nanoparticles anchored on nitrogen-doped reduced graphene oxide (Co 3 O 4 /N-rGO) as a high-performance tri-functional catalyst for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and H 2 O 2 sensing. Electrocatalytic activity of Co 3 O 4 /N-rGO to hydrogen peroxide reduction was tested by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. Under a reduction potential at -0.6 V to H 2 O 2 , this constructing H 2 O 2 sensor exhibits a linear response ranging from 0.2 to 17.5 mM with a detection limit to be 0.1 mM. Although Co 3 O 4 /rGO or nitrogen-doped reduced graphene oxide (N-rGO) alone has little catalytic activity, the Co 3 O 4 /N-rGO exhibits high ORR activity. The Co 3 O 4 /N-rGO hybrid demonstrates satisfied catalytic activity with ORR peak potential to be -0.26 V (vs. Ag/AgCl) and the number of electron transfer number is 3.4, but superior stability to Pt/C in alkaline solutions. The same hybrid is also highly active for OER with the onset potential, current density and Tafel slope to be better than Pt/C. The unusual catalytic activity of Co 3 O 4 /N-rGO for hydrogen peroxide reduction, ORR and OER may be ascribed to synergetic chemical coupling effects between Co 3 O 4 , nitrogen and graphene.