Search

We employ advanced first principles methodology, merging self‐consistent phonon theory and the Boltzmann transport equation, to comprehensively explore the thermal transport and thermoelectric properties of KCdAs. Notably, the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon lifetimes. Through various methodologies, including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes, the article unveils microphysical mechanisms contributing to the low κL within KCdAs. Key features include significant anisotropy in Cd atoms, pronounced anharmonicity in K atoms, and relative vibrations in non‐equivalent As atomic layers. Cd atoms, situated between As layers, exhibit rattling modes and strong lattice anharmonicity, contributing to the observed low κL. Remarkably flat bands near the valence band maximum translate into high PF, aligning with ultralow κL for exceptional thermoelectric performance. Under optimal temperature and carrier concentration doping, outstanding ZT values are achieved: 4.25 (a(b)‐axis, p‐type, 3 × 1019 cm−3, 500 K), 0.90 (c‐axis, p‐type, 5 × 1020 cm−3, 700 K), 1.61 (a(b)‐axis, n‐type, 2 × 1018 cm−3, 700 K), and 3.06 (c‐axis, n‐type, 9 × 1017 cm−3, 700 K). [ABSTRACT FROM AUTHOR]

Based on Zong's work [26] on translative packing densities of 3-dimensional convex bodies, we present a local method to estimate the density θt(C3) of the densest translative covering of an octahedron. As a consequence we prove that θt(C3) ≥ 1 + 6.6 × 10–8, which is the first non-trivial lower bound for this density. [ABSTRACT FROM AUTHOR]

It is a challenge to obtain highly tunable multifunctional performances in one ferroelectric system by a simple approach to meet the miniaturization, integration, and functionalization requirements of advanced electronic components. Herein, rare earth erbium (Er) modulated 0.9K0.5Na0.5NbO3-0.1Sr(1-x)ErxTi(1-x/4)O3, (0.9KNN-0.1ST: xEr) transparent-photoluminescent-ferroelectric energy storage multifunctional ceramics are prepared to solve this problem. The effect of lattice distortion and oxygen vacancies by Er doping on the optical and electrical properties is systematically investigated. The Er3+ ions can introduce a large distortion of the NbO6 octahedron by replacing the A-site in KNN-based ceramics. Thanks to the higher c/a ratio and lower oxygen vacancy content are simultaneously obtained in 0.9KNN-0.1ST: 0.1Er ceramics. The effective energy storage density (Wrec) of 0.86 J/cm3, excellent near-infrared transmittance of 51.7% (1 100 nm) and strong green upconversion photoluminescence are achieved in this multifunctional ceramic. This study provides a solid basis for rare earth ions doped ferroelectric ceramics with tunable multifunctional properties and has significant potential for applications in optoelectronic devices.

Consider an arbitrary n -dimensional lattice Λ such that Z n ⊂ Λ ⊂ Q n . Such lattices are called rational and can always be obtained by adding m ≤ n rational vectors to Z n. The defect d (E , Λ) of the standard basis E of Z n (n unit vectors going in the directions of the coordinate axes) is defined as the smallest integer d such that certain (n − d) vectors from E together with some d vectors from the lattice Λ form a basis of Λ. Let ‖ ⋅ ‖ be L 1 -norm on Q n. Suppose that for each non-integer x ∈ Λ inequality ‖ x ‖ > 1 holds. Then the unit octahedron O E n = x ∈ R n : ‖ x ‖ ⩽ 1 is called admissible with respect to Λ and d (E , Λ) is also called the defect of the octahedron O E n with respect to E and is denoted by d (O E n , Λ). Let d n = max Λ ∈ A n d (O E n , Λ) , where A n is the set of all rational lattices Λ such that O E n is admissible w.r.t. Λ. In this article we show that n − d n = Θ (log n). Let d n m = max Λ ∈ A m d (O E n , Λ) , where A m is the set of all rational lattices Λ such that 1) O E n is admissible w.r.t. Λ and 2) Λ can be obtained by adding m rational vectors to Z n : Λ = Z n , a 1 , ... , a m Z for some a 1 , ... , a m ∈ Q n. In this article we show that for any 0 < ϵ < 1 and large enough n we have m < n ϵ 8 (1 ϵ + 1) ⟹ d n m < n − n 1 − ϵ. Finally we show that for any B > 0 there exists a positive constant C > 0 such that m < C n log log n log 2 n ⟹ d n m < n − B log n. [ABSTRACT FROM AUTHOR]

Single crystals of Ba2YAlO5 and of the α and β phases of Ba6Y2Al4O15 suitable for X‐ray structure analysis were obtained via grain growth of polycrystalline samples prepared by solid‐state reactions. Ba2YAlO5 was found to have a monoclinic crystal structure, with lattice parameters a = 7.2333 (7), b = 6.0254 (5), c = 7.4294 (7) Å and β = 117.249 (3)°, and to belong to the space group P21/m, while α‐Ba6Y2Al4O15 was determined to be monoclinic, with a = 5.9019 (2), b = 7.8744 (3), c = 9.6538 (3) Å and β = 107.7940 (10)°, and the space group Pm, and β‐Ba6Y2Al4O15 was found to be monoclinic, with a = 7.8310 (2), b = 5.8990 (2), c = 18.3344 (6) Å and β = 91.6065 (11)°, and the space group P2/c. In each of these compounds, BO6 octahedra in ABO3 perovskite‐type structures were replaced by AlO4 tetrahedra and YO6 octahedra. Polycrystalline samples in which some Y atoms were replaced with Eu exhibited orange–red luminescence in the range 580–730 nm in response to exposure to radiation having a wavelength of approximately 250 nm. [ABSTRACT FROM AUTHOR]

Lattice structure metamaterials offer a variety of unique and tailorable properties, yet industrial adoption is slowed by manufacturability and inspection-related difficulties. Despite recent advances in laser powder bed fusion additive manufacturing, the sub-millimeter features of lattices are at the edge of process capabilities and suffer from low geometric quality. To better understand their complex process-structure-property (PSP) relationships, octahedron structures were manufactured across a power spectrum, inspected, and mechanically tested. X-ray computed tomography was used to characterize lattice geometry, and demonstrated that lattice strut geometry measures, increased significantly as a function of laser power. Furthermore, lattices are shown to exhibit a direct correlation between laser power and mechanical performance metrics. Performance variations up to 60% are shown as a function of process parameters despite nominally identical geometry. Significant geometry variations are found to be the cause of performance variation, while material properties as measured by microindentation hardness are constant across the studied parameter range. PSP relationships are modeled, and the limitations of these models are explored. It was found that resulting models can predict mechanical performance based on geometric characteristics with R2 values of up to 0.86. Finally, mechanistic causes of observed performance changes are discussed. [ABSTRACT FROM AUTHOR]

Vanadium is the dominant trace element and chromophore in tanzanite, the most valued gemmological variety of zoisite. The structure of zoisite–tanzanite was obtained by structural refinement to assess the vanadium location in the zoisite structure. However, the small V content in tanzanite evidenced by electron microprobe and laser ablation inductively coupled plasma mass spectrometry limits the exact determination of the V position in the zoisite structure. Structural refinement revealed that the average bond length of the less distorted M 1,2O6 octahedron is below 1.90 Å, and M 3O6 has slightly longer bonds with an average of ca. 1.96 Å. The M 1,2 site is slightly overbonded with a bond-valence sum (BVS) of 3.03 vu, whereas M 3 is slightly underbonded (BVS = 2.78 vu). Optical absorption spectra revealed that most V is trivalent, but a small portion is probably in a four-valent state. Therefore, crystal field Superposition Model and Bond-Valence Model calculations were applied based on several necessary assumptions: (1) V occupies octahedral sites; and (2) it can occur in two oxidation states, V3+ or V4+. Crystal field Superposition Model calculations from the optical spectra indicated that V3+ prefers occupying the M 1,2 site; the preference of V4+ from the present data was impossible to determine. Bond-Valence Model calculations revealed no unambiguous preference for V3+, although simple bond-length calculation suggests the preference of the M 3 site. However, it is quite straightforward that the M 1,2 site is better suitable for V4+. If the possible octahedral distortion is considered, the M 1,2O6 octahedron is subject to a smaller change in distortion if occupied by V3+ than the M 3O6 octahedron. Consequently, considering the results of both the crystal field Superposition Model and Bond-Valence Model calculations, we assume that both V3+ and V4+ prefer the M 1,2 site. [ABSTRACT FROM AUTHOR]

Due to the significance of Nb2O5 as a promising industrial and biomedical material and the importance of Raman analyses to identify nanostructural molecular responsivity for various applications, this study aims to investigate Nb2O5 molecular bands that emerged under the impact of the Raman scattering phenomenon. Besides other advantages, Raman scattering analyses can provide a further investigation of the nanostructural polycrystalline phases supporting the XRD analyses. A pulsed laser was selected as the deposition technique for Nb2O5 thin films prepared with four different parameters. The selection of the pulsed laser deposition (PLD) method was due to the insufficient studies and investigations of Nb2O5 nanostructures prepared via this method. The deposition parameters included the laser energy per pulse, substrate temperature, laser wavelength, and the number of laser pulses. Each preparation parameter was studied in a range, and one obtained value was optimized or selected for investigating the next parameter. Q-switched Nd:YAG pulsed laser was employed for this purpose. Orthorhombic (T-Nb2O5) and monoclinic (H-Nb2O5) were obtained and investigated. XRD analysis was incorporated to confirm the resulting Nb2O5 phases. Previous studies and observations of Niobium (V) oxide molecular Raman scattering bands were also listed for comparison purposes. The results of this study were well-agreed with the previously obtained results.

Mn(II)-based perovskite materials are being intensively explored for lighting applications; understanding the role of ligands regarding their photobehavior is fundamental for their development. Herein, we report on two Mn (II) bromide perovskites using monovalent (perovskite 1, P1) and bivalent (perovskite 2, P2) alkyl interlayer spacers. The perovskites were characterized with powder X-ray diffraction (PXRD), electron spin paramagnetic resonance (EPR), steady-state, and time-resolved emission spectroscopy. The EPR experiments suggest octahedral coordination in P1 and tetrahedral coordination for P2, while the PXRD results demonstrate the presence of a hydrated phase in P2 when exposed to ambient conditions. P1 exhibits an orange-red emission, while P2 shows a green photoluminescence, as a result of the different types of coordination of Mn(II) ions. Furthermore, the P2 photoluminescence quantum yield (26%) is significantly higher than that of P1 (3.6 %), which we explain in terms of different electron-phonon couplings and Mn-Mn interactions. The encapsulation of both perovskites into a PMMA film largely increases their stability against moisture, being more than 1000 h for P2. Upon increasing the temperature, the emission intensity of both perovskites decreases without a significant shift in the emission spectrum, which is explained in terms of an increase in the electron-phonon interactions. The photoluminescence decays fit two components in the microsecond regime—the shortest lifetime for hydrated phases and the longest one for non-hydrated phases. Our findings provide insights into the effects of linear mono- and bivalent organic interlayer spacer cations on the photophysics of these kinds of Mn (II)-based perovskites. The results will help in better designs of Mn(II)-perovskites, to increase their lighting performance. [ABSTRACT FROM AUTHOR]

Fractal structures with self‐similarity are of fundamental importance in the fields of aesthetic, chemistry and mathematics. Here, by taking advantage of constructs the rational geometry‐directed precursor design, we report the construction of two fascinating Platonic solids, the Sierpiński tetrahedron ST‐T and the Sierpiński octahedron ST‐O, in which each possesses a fractal Sierpiński triangle on their independent faces. These two discrete complexes are formed in near‐quantitative yield from the multi‐component self‐assembly of truncated Sierpiński triangular kernel L1 with tribenzotriquinacene‐based hexatopic and anthracene‐based tetratopic terpyridine ligands (L3 and L4) in the presence of metal ions, respectively. The enhanced stabilities of the 3D discrete structures were investigated by gradient tandem mass spectrometry (gMS2). This work provides new constructs for the imitation of complex virus assemblies and for the molecular encapsulation of giant guest molecules. [ABSTRACT FROM AUTHOR]

The author discusses the relationship between the structure of Bulienkov's T-knot and ring geological structures on the Earth's surface that have formed over eons. The positions of atoms in Bulienkov's T‑knot correspond to the vertices of Platonic solids: two tetrahedra, an icosahedron, and an octahedron (27 positions in total, including the central one). If we place the central atom of Bulienkov's T-knot at the center of a sphere (geoid) and project the remaining positions radially onto its surface, we can restore the classical ring structures known in geology on its surface using the projections as centers. Bulienkov's T-knot allows us to obtain not only a clear hierarchical relationship between the icosahedral, octahedral, and tetrahedral models of the Earth's ring structures, but to identify/confirm critical zones on the Earth known for anomalous geological structures and processes as well. [ABSTRACT FROM AUTHOR]

Let Oct 1 + and Oct 2 + be the planar and non-planar graphs, respectively, obtained from the Octahedron by 3-splitting a vertex. For Oct 1 + , we prove that if a 4-connected graph is Oct 1 + -minor-free, then it is C 6 2 , C 2 k + 1 2 (k ≥ 2) or it is obtained from C 5 2 by repeatedly 4-splitting vertices. We also show that a planar graph is Oct 1 + -minor-free if and only if it is constructed by repeatedly taking 0-, 1-, 2-sums starting from { K 1 , K 2 , K 3 } ∪ κ ∪ { O c t a h e d r o n , L 5 } , where κ is the set of graphs obtained by repeatedly taking the special 3-sums of K 4 and L 5 is the graph obtained from two 5-cycles a 1 a 2 ... a 5 a 1 , b 1 b 2 ... b 5 b 1 by adding the five edges a i b i for all 1 ≤ i ≤ 5. For Oct 2 + , we prove that if a 4-connected graph is Oct 2 + -minor-free, then it is planar, C 2 k + 1 2 (k ≥ 2) , the line graph of K 3 , 3 or it is obtained from C 5 2 by repeatedly 4-splitting vertices. [ABSTRACT FROM AUTHOR]

A mononuclear Dy(III)-based complex constructed from a phosphine oxide ligand and light halogen Cl donor displays octahedral geometry and field-induced single-molecule magnet behavior. [Display omitted] • A new Dy(III)-containing complex has been constructed from a phosphine oxide ligand and halogen Cl ligand. • The hexa -coordinated Dy(III) ions with a octahedral geometry are well-isolated in the complex. • The complex presents the field-induced single-molecule magnet behavior. We have synthesized a mononuclear Dy(III)-based complex, [Dy(CyPh 2 PO) 3 Cl 3)] (1) (CyPh 2 PO = cyclohexylbisphenylphosphine oxide), constructed from a phosphine oxide ligand and a light halogen Cl donor. The Dy(III) ion presents an octahedral geometry where two O atoms from two phosphine ligands locate at two vertexes, while the equatorial positions are completed by three Cl anions and a O atom from another phosphine ligand. Magnetism results reveal that slow relaxation of the magnetizations exists in 1 under an extra dc field because of the significant quantum tunnelling of magnetization (QTM) at 0 Oe dc field. The lighter Cl ions in equatorial plane result in a larger effect to QTM, and thus smaller contribution to slow magnetic relaxation. [ABSTRACT FROM AUTHOR]

The sintering mechanisms and temperature dependence of coalescence of colliding cubic boron nitride (c-BN) nanoparticles are investigated using classical molecular dynamics (MD) simulation. Particle-particle collisions of 2.55-nm octahedral c-BN nanoparticles, consisting solely of the most stable {111} facets, with half of the surface terminations being boron and the other half nitrogen, are analyzed statistically and evaluated to assess the initial temperature range (2500 K – 3100 K) for sintering and its effect on grain growth. At these temperatures, the collision process maximizes contact surface area through interfacial sliding, thereby minimizing free energy and accommodating dangling bonds. Moreover, the exothermic formation of bonds of the coalescing nanoparticles increases the temperature. The alignment of the {111} orientation of the two collided nanoparticles occurs at a temperature slightly above the melting point, and rapid grain growth happens when the temperature is a few hundred degrees higher than that. However, phase separation also takes place at the corners away from the collision plane of the merging nanoparticles. Between 3100 K and 3250 K, crystalline alignment occurs, which aids the sintering process and allows for the formation of a well-structured nanocluster. However, above 3300 K, phase separation dominates and drives the melting of the entire sintered nanocluster. • Initial contact of vertex-to-surface rapidly converts to edge-to-surface followed by surface-to-surface. • Two nanoparticles can slide at sufficiently high temperatures to maximize the contact area for B–N bond formation. • Crystallographic alignment of {111} facets of two nanoparticles can occur upon exceeding the melting temperature at 3000 K. • Coalescence can result in the evolvement of a good mono-crystalline {111} surface, forming a well-structured nanocluster. • Phase segregation engulfs the entire cluster when the temperature exceeds 3200 K. [ABSTRACT FROM AUTHOR]

In this work, fabrication of Cu2O@Cu1.75S core‐shell octahedrons was achieved through a facile water bath stirring process. Compared with pure Cu2O, the composite showed enhanced sensing performance for NO2. The response value of Cu2O@Cu1.75S to 5 ppm NO2 at 40 °C is seven times that of Cu2O to 5 ppm NO2 at 75 °C. Moreover, Cu2O@Cu1.75S has the ability to detect 100 ppb NO2 and has good NO2 sensing selectivity and long‐term stability. This study shows that Cu2O@Cu1.75S hybrid is a type of outstanding NO2 gas sensing material on account of its low working temperature and high sensing sensitivity. [ABSTRACT FROM AUTHOR]

Nitrate and nitrite are widely present in industrial wastewater and domestic sewage, so electrocatalytic reduction of both nitrate and nitrite to ammonia synthesis is considered to be a sustainable development approach. Pd nanostructures have attracted much attention because of their high activity in catalyzing the nitrate electrochemical reduction reaction. Here we prepare Pd nanocube and octahedron for the electrochemical reduction of nitrate and nitrite. It is found that Pd octahedron shows slightly higher activity toward nitrate reduction than Pd nanocube, while for nitrite reduction, Pd octahedron shows much higher activity than Pd nanocube. The ammonia yield rate is more potential-dependent. In situ Raman characterization further confirms the existence of adsorbed ammonia on the surface of nanocube and octahedron, indicating similar reduction pathways on (111)-facet octahedron and (100)-facet nanocube., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Triethylamine (TEA) is typical hazardous volatile organic gas (VOCs), it is particularly important for us to effectively detect triethylamine in complex places. In this work, high efficiency triethylamine gas sensor based on SmVO 4 was successfully obtained by means of hydrothermal reaction and assisted calcination. Characterization of analytical materials, SmVO 4 octahedral nanoparticles formed clusters similar to pomegranate fruits. There is a trace +4 valence state of vanadium in the material, which contributes to the oxidation-reduction reaction between the target gas and the surface of the material. Gas sensitive test results found that the SmVO 4 sensor still has a 2.45 response to the target gas (triethylamine) at low concentrations (1 ppm). SmVO 4 shows excellent selectivity for triethylamine, with a response value more than three times that of other gases. In 25 days, it shows excellent stability and fast response recovery time (15 s/40 s). In addition, the gas sensing mechanism is analyzed. [Display omitted] • The octahedral SmVO 4 material was prepared by a simple method. • The gas sensitive performance of the SmVO 4 gas sensor for triethylamine was first investigated. • The SmVO 4 gas sensor provides efficient identification in low triethylamine atmospheres. [ABSTRACT FROM AUTHOR]

It is impossible to imagine the development of high-tech sectors of the Russian economy without the emergence and active growth of a large number of small innovative enterprises that create and promote demanded competitive goods and services on the Russian and international markets. The development of this type of company often requires the attraction of so-called “comfortable” venture capital. The main source of such capital in the early stages of development of small innovative companies is business angels. However, the evaluation of innovative projects at an early stage of development and the decision-making of business angels about investing is a rather time-consuming process, involving the analysis and systematization of a huge amount of information.The article proposes 56 criteria for evaluating innovative projects of early stages of development. The criteria have been divided into 8 groups specific to the evaluation of projects. These criteria typically use grading scales. The most commonly used are 10-point, 5-point, 100-point rating scales and 0…1 scale.It was proposed to evaluate innovative projects of the early stages of development not only according to the rating scale, but also using colors. Red (for negative assessments) and blue (for positive assessments) colors gradients have been used in the article. An example of constructing a colorographic map based on a fictional innovative project has been adduced. The developed colorographic maps will allow the investor to evaluate visually the information on the investment application submitted for consideration using a two-dimensional image (this is essentially a table).The visualization of project estimates in the form of a colored octahedron has been presented. In constructing the octahedron, red, blue and white (no grade) gradients were also used. Each face of the octahedron corresponds to a group of criteria of this project. The criteria in the group are located in such a way that when reflected on the plane they will be located closer to the center of the octahedron. Thus, in the case of saturated color of the center of the octahedron, the project can receive either an excellent, or unsatisfactory rating. This visualization of the project can be useful if you need to analyze each group of criteria separately.

Mn(II)-based perovskite materials are being intensively explored for lighting applications; understanding the role of ligands regarding their photobehavior is fundamental for their development. Herein, we report on two Mn (II) bromide perovskites using monovalent (perovskite 1, P1) and bivalent (perovskite 2, P2) alkyl interlayer spacers. The perovskites were characterized with powder X-ray diffraction (PXRD), electron spin paramagnetic resonance (EPR), steady-state, and time-resolved emission spectroscopy. The EPR experiments suggest octahedral coordination in P1 and tetrahedral coordination for P2, while the PXRD results demonstrate the presence of a hydrated phase in P2 when exposed to ambient conditions. P1 exhibits an orange-red emission, while P2 shows a green photoluminescence, as a result of the different types of coordination of Mn(II) ions. Furthermore, the P2 photoluminescence quantum yield (26%) is significantly higher than that of P1 (3.6 %), which we explain in terms of different electron-phonon couplings and Mn-Mn interactions. The encapsulation of both perovskites into a PMMA film largely increases their stability against moisture, being more than 1000 h for P2. Upon increasing the temperature, the emission intensity of both perovskites decreases without a significant shift in the emission spectrum, which is explained in terms of an increase in the electron-phonon interactions. The photoluminescence decays fit two components in the microsecond regime—the shortest lifetime for hydrated phases and the longest one for non-hydrated phases. Our findings provide insights into the effects of linear mono- and bivalent organic interlayer spacer cations on the photophysics of these kinds of Mn (II)-based perovskites. The results will help in better designs of Mn(II)-perovskites, to increase their lighting performance.

Copyright of Eastern-European Journal of Enterprise Technologies is the property of PC TECHNOLOGY CENTER and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

GLO:1CJF/01may21:bkcs12183-fig-0003.jpg PHOTO (COLOR): 3 Electrochemical characterization of the Pd octahedra/C, PdH octahedra/C, Pd cubes/C, and PdH cubes/C catalysts. The ORR mass activities for Pd octahedra/C, PdH octahedra/C, Pd cubes/C, and PdH cubes/C were 0.007, 0.014, 0.124, and 0.041 A mg SB Pd sb SP -1 sp at 0.9 V (vs. The measured ECSA SB CO sb s were 58.34, 57.51, 61.83, and 57.2 m SP 2 sp g SP -1 sp SB Pd sb for Pd octahedra/C, PdH octahedra/C, Pd cubes/C, and PdH cubes/C, respectively. Keywords: Palladium hydride; Oxygen reduction reaction; Catalyst; Octahedron; Cube EN Palladium hydride Oxygen reduction reaction Catalyst Octahedron Cube 802 805 4 05/27/21 20210501 NES 210501 Oxygen reduction reaction (ORR) performances of palladium nanocubes and octahedra and their hydride forms were investigated. [Extracted from the article]

Significant efforts have been dedicated to boosting the electrocatalytic activity of Co9S8 for the oxygen evolution reaction (OER); however, with limited improvement in its intrinsic activity, which relies on careful band engineering. Fe possesses one less 3d electron and lower electronegativity than Co, suggesting a higher d‐band center when forming polyhedron with S anions. Here, to improve the intrinsic activity by elevating the d‐band center, the six‐coordinated octahedrons in Co9S8 are redesigned utilizing an Fe‐incorporated topochemical deintercalation method. Through substituting partial Co octahedrons by Fe octahedrons with higher d‐band, the overall d‐band center is regulated to achieve optimized adsorption and thus superior OER activity. With a reduction of 95 mV on the overpotential (at 10 mA cm−2), this work sheds lights on the design of OER catalysts through polyhedron engineering using topochemical deintercalation. [ABSTRACT FROM AUTHOR]

Transition metal (TM)‐based bimetallic spinel oxides can efficiently activate peroxymonosulfate (PMS) presumably attributed to enhanced electron transfer between TMs, but the existing model cannot fully explain the efficient TM redox cycling. Here, we discover a critical role of TM−O covalency in governing the intrinsic catalytic activity of Co3−xMnxO4 spinel oxides. Experimental and theoretical analysis reveals that the Co sites significantly raises the Mn valence and enlarges Mn−O covalency in octahedral configuration, thereby lowering the charge transfer energy to favor MnOh–PMS interaction. With appropriate MnIV/MnIII ratio to balance PMS adsorption and MnIV reduction, the Co1.1Mn1.9O4 exhibits remarkable catalytic activities for PMS activation and pollutant degradation, outperforming all the reported TM spinel oxides. The improved understandings on the origins of spinel oxides activity for PMS activation may inspire the development of more active and robust metal oxide catalysts. [ABSTRACT FROM AUTHOR]

In civil engineering, there is an occasional need to assure an additional support for a structure due to the loss of the load carrying capacity (e.g., as a result of natural disasters or aging) or for a lightweight structure to support temporary objects (e.g., tents, big advertisement banners, temporary antenna masts). In the present study, the authors propose deployable tensegrity columns to be used in such cases. This paper is aimed at answering the question: Which tensegrity column would be the best for the specified application? Four tensegrity columns are analyzed in various deployment configurations to find the answer to this question. Computer simulations are performed in the finite element (FE) and multibody dynamics (MBD) software to provide quantitative and qualitative results. The applied methods are validated by comparing self-stress states at various steps of the analysis. The most important part of the article is the comparative table, which contains quantitative results obtained from the performed analyses, which can be used to indicate the structures that are most appropriate for certain applications. The results may also be used as a starting point for research in other fields of science like robotics or mechatronics. This paper is focused on obtaining full data for building scaled models for laboratory tests in the future. [ABSTRACT FROM AUTHOR]

In order to understand sulfur solubility in the MnO–SiO2–Al2O3–Ce2O3 slag or inclusion system (mol MnO/mol SiO2 = M/S = 2.2 or 0.9, Al2O3 = 14.2[± 1.8] mol%, Ce2O3 = 0–5.6 mol%), the effect of Ce3+ ions on the structure of the Mn–aluminosilicate system with different M/S molar ratios has been studied by micro-Raman spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Because constant oxygen partial pressure was maintained at p(O2) = 2.8 × 10−7 atm, oxidation state of Mn and Ce would be in Mn2+ and Ce3+ in the MnO–SiO2–Al2O3–Ce2O3 system, which were also confirmed by XPS analysis. Although it was difficult to measure the 27Al solid-state NMR spectra of the quenched MnO–SiO2–Al2O3 system due to the paramagnetic effect, 27Al NMR spectra did show structural changes in aluminate when cerium was added to the Mn–aluminosilicate melts. Addition of Ce2O3 in the high M/S(= 2.2) system caused both an explosive enhancement in the intensity of Raman bands at 600 cm−1 and a peak shift in 27Al NMR spectra, indicating the transition from the [AlO4]–:0.5Mn2+ tetrahedron to a [AlO6]3–:Ce3+ octahedron complex due to a strong attraction between aluminate and the cerium ion. XPS spectra show that the transition of the aluminate structure upon introduction of Ce3+ ions consumes free oxygen in Mn–aluminosilicate melts in high M/S(= 2.2) system. However, the same structural changes were not observed when Ce2O3 was added to lower M/S(= 0.9) system, because Ce3+ ions primarily interact with the pre-existing [AlO6]-octahedron in low M/S system. [ABSTRACT FROM AUTHOR]

Consider an arbitrary n -dimensional lattice Λ such that Z n ⊂ Λ ⊂ Q n . Such lattices are called rational and can always be obtained by adding m ⩽ n rational vectors to Z n. The defect d (E , Λ) of the standard basis E of Z n (n unit vectors going in the directions of the coordinate axes) is defined as the smallest integer d such that certain (n − d) vectors from E together with some d vectors from the lattice Λ form a basis of Λ. Let | | ⋅ | | be L 1 -norm on Q n. Suppose that for each non-integer x ∈ Λ inequality | | x | | > 1 holds. Then the unit octahedron O n = x ∈ R n : | | x | | ⩽ 1 is called admissible with respect to Λ and d (E , Λ) is also called the defect of the octahedron O n with respect to E and is denoted by d (O E n , Λ). Let d n m = max Λ ∈ A m d (O E n , Λ) , where A m is the set of all rational lattices Λ such that (1) O n is admissible w.r.t. Λ and (2) Λ can be obtained by adding m rational vectors to Z n : Λ = Z n , a 1 , ... , a m Z for some a 1 , ... , a m ∈ Q n. In this article we show that there exists an absolute positive constant C such that for any m < n d n m ⩽ C n ln (m + 1) ln n m ln ln n m m 2 This bound was also claimed in [2] and [1] , however the proof was incorrect. In this article along with giving correct proof we highlight substantial inaccuracies in those articles. [ABSTRACT FROM AUTHOR]

Making consistent and precise octahedral pressure media is crucial for reproducible high-pressure experiments in the multi-anvil press. Here we report a new approach of casting octahedra using 3D-printed molds, and pressure calibrations for octahedra both with and without pre-existing gaskets ("fins"). The 3D-printed molds for casting octahedra from either Ceramacast 584-OF or 646 cement improve the reproducibility of the octahedra and allow for a pre-existing central hole (for the high-pressure cell assembly) in the final cast product. Pressure and temperature calibrations of the octahedra have been performed based on phase transitions in bismuth (Bi) and silica (SiO2), respectively, in order to determine the efficiency and reproducibility of pressure generation and thermal insulation for cast octahedra designed for use with 18/12, 14/8, and 10/5 multi-anvil assemblies. The pressure-generating efficiency of the 14/8 and 10/5 octahedra with pre-existing gaskets, cast from the 584-OF cement, is similar to that of the corresponding COMPRES (Consortium for Materials Properties Research in Earth Sciences) octahedra, and more efficient than pre-cast octahedra made from the same material but lacking pre-existing gaskets. The efficiency of pre-gasketed 18/12 octahedra made of the 646 cement is markedly lower than those of the 584 cement. However, the 18/12 large-volume octahedra, cast (with fins) from the ZrO2-based 646 cement, also provides efficient thermal insulation. Casting octahedral solid pressure media for multi-anvil experiments using 3D-printed "injection" molds is a low-cost and low failure-rate alternative for conducting reproducible experiments at high pressure in the multi-anvil apparatus. [ABSTRACT FROM AUTHOR]

In this work, octahedral shaped PbTiO3-TiO2 nanocomposites have been synthesized by a facile hydrothermal method, where perovskite ferroelectric PbTiO3 nanooctahedra were employed as substrate. The microstructures of the composites were investigated systemically by using XRD, SEM, TEM and UV-Vis spectroscopy. It was revealed that anantase TiO2 nanocrystals with a size of about 5 nm are dispersed on the surface of the {111} facets of the nanooctahedron crystals. Photocatalytic hydrogen production of the nanocomposites has been evaluated in a methanol alcohol-water solution under UV light enhanced irradiation. The H2 evolution rate of the nanocomposites increased with an increased loading of TiO2 on the nanooctahedra. The highest H2 evolution rate was 630.51 μmol/h with the highest concentration of TiO2 prepared with 2 mL tetrabutyl titanate, which was about 36 times higher than that of the octahedron substrate. The enhanced photocatalytic reactivity of the nanocomposites is possibly ascribed to the UV light absorption of the nanooctahedral substrates, efficient separation of photo-generated carriers via the interface and the reaction on the surface of the TiO2 nanocrystals.

Octahedral core-shell ZIF-67a/b@CuOx (a/b=4/1,2/1,1/1,1/1.5) coated with nano particle ZIF-67 catalyst for low temperature denitrification was prepared by encapsulation method at room temperature and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (IR), scanning electron microscopy (SEM), specific surface area analyzer (BET). The effect of different amounts of ZIF-67 on the morphology, composition, specific surface area of catalysts and the catalytic reduction performance was studied. The results showed that octahedral CuOx derived by HKUST-1 sintered had good carrying capacity, and the morphology, crystal structure and great BET value of ZIF-67 were kept. When a/b was 4/1, better uniformity and higher dispersion of ZIF-67 and larger specific surface area of catalyst, and the best catalytic low-temperature denitrification were obtained. The catalysts activity of CO-SCR results showed that denitrification rate of ZIF-674/1@CuOx was 86.5% and 95% at 150 and 225°C respectively. The temperature of ZIF-674/1@CuOx was 50°C lower than that of ZIF-67 at the same denitrification rate (86%). Specific surface area of ZIF-674/1@CuOx was largest, 1168.410 m²/g, which provided more reaction interfaces and effective contacts and improved the catalytic denitrification rate. [ABSTRACT FROM AUTHOR]

Smart surface coatings composed of transition‐metal oxides are shown to significantly improve the cycling performance of batteries. Currently, most studies are mainly focused on coating materials such as TiO2 and carbon‐based materials. However, these coating materials face significant challenges, including their low capacity and tedious processing. Herein, a simple and novel amorphous SiO2 coating is successfully used on the surface of NiFe2O4 to form a core‐shell structure. When tested as an anode, it delivers a high initial discharge capacity of 2022.3 mAh g−1 and retains a high specific capacity of 1224.6 mAh g−1 after 100 cycles at a current density of 0.1 C. The superior performance of NiFe2O4@SiO2 is mainly attributed to the SiO2 coatings, which can provide a high capacity, alleviate drastic volume changes in NiFe2O4 and form a stable solid electrolyte interphase (SEI) layer. The results demonstrated that SiO2 can be used as a novel coating material to improve the cycling properties of metal oxide materials. A NiFe2O4@SiO2 nanocomposite with octahedral structure is prepared by an effective and cost‐effective method. The material exhibits superior lithium‐storage properties (1224 mAh g−1 at 0.1 C upon 100 cycles), which can be mainly attributed to the SiO2 coating, which can provide a high capacity, alleviate drastic volume changes in NiFe2O4, and form a stable solid electrolyte interphase (SEI) layer. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a facile molten-salt strategy is developed for controllably synthesizing LiNbO 3 microcrystals shaped as octahedrons and cubes in molten LiNO 3 and LiCl salts without using any capping agents. The as-prepared LiNbO 3 micro-octahedrons and micro-cubes are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Our results show that the formation of LiNbO 3 micro-octahedrons and micro-cubes can be attributed to a dissolution-nucleation-aggregation-recrystallization process. Furthermore, in order to minimize the surface and interface energies between the constituents and the salts, octahedral and cubic morphology forms under different molten-salt conditions, which shows the anion may play a crucial role in tuning the product morphology. [ABSTRACT FROM AUTHOR]

• A novel NiSe 2 @MXene/rGO aerogel (NSMGA) was fabricated with different mass loading of Ti 3 C 2 MXene. • NSMGA applied as multifunctional electrode material for supercapacitor study and overall water splitting. • The optimal electrode (NSMGA-40) exhibited excellent electrochemical performance. • NSMGA-40 showed remarkable stability during electrochemical applications. In this research, we have designed novel three-dimensional (3D) Ti 3 C 2 MXene/rGO composite aerogels (MGA) integrated with octahedron-like NiSe 2 (NS), with different mass loadings of MXene (20 wt% and 40 wt%). Resultant aerogels developed into a cellular lattice like network that significantly improved the contact area among active material and electrolyte. 3D spongy scaffold of MGA boosted the mass diffusion rate, and good electrical conductivity of MXene and rGO provided fast transport of charges during the electrochemical tests, which endowed superior supercapacitor and water splitting performances. Electrode with optimized MXene/rGO ratio i.e., NSMGA-40, exhibited a remarkable specific capacity of 289.7 mAh g−1 at current density of 1 A g−1 and excellent durability of 92.5% over 5000 charge/discharge cycles at 12 A g−1 in a three electrode system for supercapacitor. Meanwhile, as a bifunctional electrocatalyst, NSMGA-40 required a low overpotential of 97 mV and 262 mV to reach 10 mA cm−2 for HER and OER activity, respectively, in alkaline media. The values of Tafel slopes were as small as 89 mV dec−1 (HER) and 75 mV dec−1 (OER), signifying accelerated electron-transfer kinetics. Furthermore, in both cases, NSMGA-40 electrocatalyst withstood a long-term stability test of 10 h. Hence, the obtained results can be manifested for the structural and componential engineering that maximizes the synergetic effects from Ti 3 C 2 MXene, rGO, and NS. Indeed, our fabricated aerogels offer a valuable reference for the fabrication of 3D multicomponent electrode materials for energy storage and conversion applications. [ABSTRACT FROM AUTHOR]