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Red, green, and blue light In x Ga 1-x N multiple quantum wells have been grown on GaN/γ-LiAlO 2 microdisk substrates by plasma-assisted molecular beam epitaxy. We established a mechanism to optimize the self-assembly growth with ball-stick model for In x Ga 1-x N multiple quantum well microdisks by bottom-up nanotechnology. We showed that three different red, green, and blue lighting micro-LEDs can be made of one single material (In x Ga 1-x N) solely by tuning the indium content. We also demonstrated that one can fabricate a beautiful In x Ga 1-x N-QW microdisk by choosing an appropriate buffer layer for optoelectronic applications.

Objective. Together with novel photodetector technologies and emerging electronic front-end designs, scintillator material research is one of the key aspects to obtain ultra-fast timing in time-of-flight positron emission tomography (TOF-PET). In the late 1990s, Cerium-doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) has been established as the state-of-the-art PET scintillator due to its fast decay time, high light yield and high stopping power. It has been shown that co-doping with divalent ions, such as Ca 2+ and Mg 2+ , is beneficial for its scintillation characteristics and timing performance. Therefore, this work aims to identify a fast scintillation material to combine it with novel photosensor technologies to push the state of the art in TOF-PET. Approach. This study evaluates commercially available LYSO:Ce,Ca and LYSO:Ce,Mg samples manufactured by Taiwan Applied Crystal Co., LTD regarding their rise and decay times as well as their coincidence time resolution (CTR) with both ultra-fast high-frequency (HF) readout and commercially available readout electronics, i.e. the TOFPET2 ASIC. Main results. The co-doped samples exhibit state-of-the-art rise times of on average 60 ps and effective decay times of on average 35 ns. Using the latest technological improvements made on NUV-MT SiPMs by Fondazione Bruno Kessler and Broadcom Inc., a 3 × 3 × 19 mm 3 LYSO:Ce,Ca crystal achieves a CTR of 95 ps (FWHM) with ultra-fast HF readout and 157 ps (FWHM) with the system-applicable TOFPET2 ASIC. Evaluating the timing limits of the scintillation material, we even show a CTR of 56 ps (FWHM) for small 2 × 2 × 3 mm 3 pixels. A complete overview of the timing performance obtained with different coatings (Teflon, BaSO 4 ) and different crystal sizes coupled to standard Broadcom AFBR-S4N33C013 SiPMs will be presented and discussed. Significance. This work thoroughly evaluates commercially available co-doped LYSO:Ce crystals and, in combination with novel NUV-MT SiPMs, shows a TOF performance that significantly exceeds the current state of the art., (Creative Commons Attribution license.)

This study reports a simplified method to grow CuAlO 2 crystals of submillimeter sizes with a highly anisotropic shape of a platelet. The solid-state reaction of forming CuAlO 2 at ca. 1373 K in the first stage of the conventional flux method is no longer required. The CuAlO 2 platelets nucleated directly onto the (0001) sapphire surface in a melt of Cu 2 O saturated with Al 2 O 3 at 1473 K. The excess flux was mostly removed by the capped alumina plate on cooling with a limited amount of residue which can be leached afterward. The CuAlO 2 platelets all have a 3R crystal structure with no line and planar defects observed by TEM. The CuAlO 2 crystals emit a luminescence at 3.49 eV associated with resonant Raman effect resulted from a band-to-band transition in room-temperature PL measurement. The facile fabrication method for growing highly anisotropic CuAlO 2 crystals paves the way for their practical application in photoelectrochemical devices., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The development of modern cutting-edge technology relies heavily on the huge success and advancement of nanotechnology, in which nanomaterials and nanostructures provide the indispensable material cornerstone. Owing to their nanoscale dimensions with possible quantum limit, nanomaterials and nanostructures possess a high surface-to-volume ratio, rich surface/interface effects, and distinct physical and chemical properties compared with their bulk counterparts, leading to the remarkably expanded horizons of their applications. Depending on their degree of spatial quantization, low-dimensional nanomaterials are generally categorized into nanoparticles (0D); nanorods, nanowires, and nanobelts (1D); and atomically thin layered materials (2D). This review article provides a comprehensive guide to low-dimensional nanomaterials and nanostructures. It begins with the classification of nanomaterials, followed by an inclusive account of nanofabrication and characterization. Both top-down and bottom-up fabrication approaches are discussed in detail. Next, various significant applications of low-dimensional nanomaterials are discussed, such as photonics, sensors, catalysis, energy storage, diverse coatings, and various bioapplications. This article would serve as a quick and facile guide for scientists and engineers working in the field of nanotechnology and nanomaterials.

The magnetization measurement was performed in the Bi 0.3 Sb 1.7 Te 3 single crystal. The magnetic susceptibility revealed a paramagnetic peak independent of the experimental temperature variation. It is speculated to be originated from the free-aligned spin texture at the Dirac point. The ARPES reveals that the Fermi level lies below the Dirac point. The Fermi wavevector extracted from the de Haas-van Alphen oscillation is consistent with the energy dispersion in the ARPES. Our experimental results support that the observed paramagnetic peak in the susceptibility curve does not originate from the free-aligned spin texture at the Dirac point., (© 2022. The Author(s).)

The magnetic susceptibility reveals a discontinuity at Néel temperature and a hysteresis loop with low coercive field was observed below Néel temperature. The magnetic susceptibility of zero field cool and field cool processes coincide at a temperature above the discontinuity, and they split at temperature blow the discontinuity. The magnetic susceptibility splitting is larger at lower external magnetic fields. No more magnetic susceptibility splitting was observed at a magnetic field above 7000 Oe which is consistent with the magnetic anisotropy energy. Our study supports that these magnetic susceptibility characteristics originate from an antiferromagnetic order accompanied by weak ferromagnetism., (© 2021. The Author(s).)

The computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication technique has become one of the hottest topics in the dental field. This technology can be applied to fixed partial dentures, removable dentures, and implant prostheses. This study aimed to evaluate the feasibility of NaCaPO 4 -blended zirconia as a new CAD/CAM material. Eleven different proportional samples of zirconia and NaCaPO 4 ( x Z y N) were prepared and characterized by X-ray diffractometry (XRD) and Vickers microhardness, and the milling property of these new samples was tested via a digital optical microscope. After calcination at 950 °C for 4 h, XRD results showed that the intensity of tetragonal ZrO 2 gradually decreased with an increase in the content of NaCaPO 4 . Furthermore, with the increase in NaCaPO 4 content, the sintering became more obvious, which improved the densification of the sintered body and reduced its porosity. Specimens went through milling by a computer numerical control (CNC) machine, and the marginal integrity revealed that being sintered at 1350 °C was better than being sintered at 950 °C. Moreover, 7Z3N showed better marginal fit than that of 6Z4N among thirty-six samples when sintered at 1350 °C ( p < 0.05). The milling test results revealed that 7Z3N could be a new CAD/CAM material for dental restoration use in the future.

For efficient solar energy harvesting, various engineering strategies to strengthen visible-light responsivity of ZnO photocatalyst is under intensive investigation. In this work, a new ternary C-ZnO/MoS 2 /mesoporous carbon nanocomposite was successfully prepared by a two-step solution-processed synthesis protocol. The ternary composite exhibits a well-interconnected 3D mesoporous microstructure assembled by carbon nanosheets, which is loaded with quasi 0D ZnO nanoparticles and 2D MoS 2 nanosheets. The carbonaceous nanocomposites show enhanced visible-light-driven photocatalytic performance and high photo-corrosion resistance. The incorporation of carbon in the hybrid design has manifold benefits that drastically promotes the photoactivity and photostability. The significant enhancement in photodegradation activity of the hybrid catalysts can be ascribed to a few positive synergistic effects, such as increased surface area and active reaction sites, boosted surface charge utilization efficiency, and band-gap lowering. The high porosity of the distinct microstructure raises the dye adsorption within the material. Tailored interface/surface properties enable more effective mass transport and higher separation efficiency of photo-generated carriers. The modulated electronic structure leads to the narrowing of the ZnO optical bandgap. Meanwhile, coupling with carbon prevents ZnO from photo-corrosion. Our approach highlights the roles of carbon as structure directing and stabilizing agents as well as heteroatom in defect engineering for wide band-gap oxide materials. The rational material design of multivariate mixed-dimensional architecture also provides guiding insight for the advancement of heterogeneous photocatalyst materials with superior performance and durability. The presented engineering strategy would be a promising method for the preparation of nanomaterials supported on 3D carbon network with high porosity and visible-light-driven photocatalytic performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

We report the facile and economic preparation of two-dimensional (2D) and 0D MoSe 2 nanostructures based on systematic and non-toxic top-down strategies. We demonstrate the intrinsic peroxidase-like activity of these MoSe 2 nanostructures. The catalytic processes begin with facilitated decomposition of H 2 O 2 by using MoSe 2 nanostructures as peroxidase mimetics. In turn, a large amount of generated radicals oxidizes 3,3,5,5-tetramethylbenzidine (TMB) to produce a visible color reaction. The enzymatic kinetics of our MoSe 2 nanostructures complies with typical Michaelis-Menten theory. Catalytic kinetics study reveals a ping-pong mechanism. Moreover, the primary radical responsible for the oxidation of TMB was identified to be Ȯ 2 - by active species-trapping experiments. Based on the peroxidase mimicking property, we developed a new colorimetric method for H 2 O 2 detection by using 2D and 0D MoSe 2 nanostructures. It is shown that the colorimetric sensing capability of our MoSe 2 catalysts is comparable to other 2D materials-based colorimetric platforms. For instance, the linear range of H 2 O 2 detection is between 10 and 250 μM by using 2D functionalized MoSe 2 nanosheets as an artificial enzyme. Our work develops a systematic approach to use 2D materials to construct novel enzyme-free mimetic for a visual assay of H 2 O 2 , which has promising prospects in medical diagnosis and food security monitoring.

We study the quantum oscillations in the BiSbTe 3 topological insulator. In addition to the Shubnikov-de Haas (SdH) oscillation, the Aharonov-Bohm-like (ABL) oscillations are also observed. The ABL oscillation period is constant at each Landau level (LL) which is determined from the SdH oscillation. The shorter ABL oscillation periods are observed at lower LLs. The oscillation period is proportional to the square root of the LL at temperatures. The ratio of the ABL oscillation period to the effective mass is weak LL dependence. The LL-dependent ABL oscillation might originate from the LL-dependent effective mass.

The temperature-dependent polarized photoluminescence spectra of nonpolar ZnO samples were investigated by 263 nm laser. The degree of polarization (DOP) of m-plane quantum wells changes from 76% at 10 K to 40% at 300 K, which is much higher than that of epilayer. The strong anisotropy was presumably attributed to the enhanced confinement effect of a one-dimension confinement structure formed by the intersection of quantum well and basal stacking fault. The polarization of laser beam also has an influence on the DOP. It is assumed that the luminescence polarization should be affected not only by the in-plane strains but also the microstructural defects, which do modify the electronic band structure.

Photoluminescent zero-dimensional (0D) quantum dots (QDs) derived from transition metal dichalcogenides, particularly molybdenum disulfide, are presently in the spotlight for their advantageous characteristics for optoelectronics, imaging, and sensors. Nevertheless, up to now, little work has been done to synthesize and explore photoluminescent 0D WS 2 QDs, especially by a bottom-up strategy without using usual toxic organic solvents. In this work, we report a facile bottom-up strategy to synthesize high-quality water-soluble tungsten disulfide (WS 2 ) QDs through hydrothermal reaction by using sodium tungstate dihydrate and L-cysteine as W and S sources. Besides, hybrid carbon quantum dots/WS 2 QDs were further prepared based on this method. Physicochemical and structural analysis of QD hybrid indicated that the graphitic carbon quantum dots with diameters about 5 nm were held onto WS 2 QDs via electrostatic attraction forces. The resultant QDs show good water solubility and stable photoluminescence (PL). The excitation-dependent PL can be attributed to the polydispersity of the synthesized QDs. We found that the PL was stable under continuous irradiation of UV light but can be quenched in the presence of hydrogen peroxide (H 2 O 2 ). The obtained WS 2 -based QDs were thus adopted as an electrodeless luminescent probe for H 2 O 2 and for enzymatic sensing of glucose. The hybrid QDs were shown to have a more sensitive LOD in the case of glucose sensing. The Raman study implied that H 2 O 2 causes the partial oxidation of QDs, which may lead to oxidation-induced quenching. Overall, the presented strategy provides a general guideline for facile and low-cost synthesis of other water-soluble layered material QDs and relevant hybrids in large quantity. These WS 2 -based high-quality water-soluble QDs should be promising for a wide range of applications in optoelectronics, environmental monitoring, medical imaging, and photocatalysis.

In this work, a high thermoelectric figure of merit, zT of 1.9 at 740 K is achieved in Ge 1-x Bi x Te crystals through the concurrent of Seebeck coefficient enhancement and thermal conductivity reduction with Bi dopants. The substitution of Bi for Ge not only compensates the superfluous hole carriers in pristine GeTe but also shifts the Fermi level (E F ) to an eligible region. Experimentally, with moderate 6-10% Bi dopants, the carrier concentration is drastically decreased from 8.7 × 10 20  cm -3 to 3-5 × 10 20  cm -3 and the Seebeck coefficient is boosted three times to 75 μVK -1 . In the meantime, based on the density functional theory (DFT) calculation, the Fermi level E F starts to intersect with the pudding mold band at L point, where the band effective mass is enhanced. The enhanced Seebeck coefficient effectively compensates the decrease of electrical conductivity and thus successfully maintain the power factor as large as or even superior than that of the pristine GeTe. In addition, the Bi doping significantly reduces both thermal conductivities of carriers and lattices to an extremely low limit of 1.57 W m -1 K -1 at 740 K with 10% Bi dopants, which is an about 63% reduction as compared with that of pristine GeTe. The elevated figure of merit observed in Ge 1-x Bi x Te specimens is therefore realized by synergistically optimizing the power factor and downgrading the thermal conductivity of alloying effect and lattice anharmonicity caused by Bi doping.

The aim of this study is to determine the minimum required thickness of a monolithic zirconia crown in the mandibular posterior area for patients with bruxism. Forty-nine full zirconia crowns, with seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm, were made by using a computer-aided design/computer-aided manufacturing system (CAD/CAM). Seven crowns in each group were subjected to cyclic loading at 800 N and 5 Hz in a servohydraulic testing machine until fracture or completion of 100,000 cycles. Seven finite element models comprising seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm were simulated using three different loads of vertical 800 N, oblique 10 degrees 800 N, and vertical 800 N + x N torque (x = 10, 50, and 100). The results of cyclic loading tests showed that the fracture resistance of the crown was positively associated with thickness. Specimen breakage differed significantly according to the different thicknesses of the prostheses ( p < 0.01). Lowest von Mises stress values were determined for prostheses with a minimal thickness of 1.0 mm in different loading directions and with different forces. Zirconia specimens of 1.0 mm thickness had the lowest stress values and high fracture resistance and under 800 N of loading.

The photocurrent was performed in topological insulator nanosheets with different conductances. The higher photocurrent is observed in the nanosheet with higher conductance. The responsivity is proportional to the nanosheet conductance over two orders. The responsivity is independent of the light power intensity in vacuum, but responsivity drastically decreases at low power intensity in air. The ratio of the responsivity in air to that in vacuum is negatively proportional to the the inverse of the light power intensity. These behaviors are understood as the statistical photocurrent in a system with blocked molecules. The time constant decreases as the thickness increases. A longer time constant is observed in lower atmosphere pressure.

The functionalities of porous materials could be significantly enhanced if the materials themselves were in single-crystal form, which, owing to structural coherence, would reduce electronic and optical scattering effects. However, growing macroporous single crystals remains a fundamental challenge, let alone manufacturing crystals large enough to be of practical use. Here we demonstrate a straightforward, inexpensive, versatile method for creating macroporous gallium nitride single crystals on a centimetre scale. The synthetic strategy is built upon a disruptive crystal growth mechanism that utilises direct nitridation of a parent LiGaO 2 single crystal rendering an inward epitaxial growth process. Strikingly, the resulting single crystals exhibit electron mobility comparable to that for bulk crystals grown by the conventional sodium flux method. This approach not only affords control of both crystal and pore size through synthetic modification, but proves generic, thus opening up the possibility of designing macroporous crystals in a wealth of other materials.

M -plane GaN thin films were grown on LiAlO 2 substrates under different N/Ga flux ratios by plasma-assisted molecular beam epitaxy. An anisotropic growth of M -plane GaN was demonstrated against the N/Ga flux ratio. As the N/Ga flux ratio decreased by increasing Ga flux, the GaN surface trended to a flat morphology with stripes along [11[Formula: see text]0]. According to high-resolution X-ray diffraction analysis, Li 5 GaO 4 was observed on the interface between GaN and LiAlO 2 substrate. The formation of Li 5 GaO 4 would influence the surface morphology and crystal quality.