A Study of Al2O3/MgO Composite Films Deposited by FCVA for Thin-Film Encapsulation

Al₂O₃ and MgO composite (Al₂O₃/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al₂O₃:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10^-4 g·m^-2·day^-1 at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al₂O₃ film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3-0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers.

The Total Ionizing Dose Effects on Perovskite CsPbBr3 Semiconductor Detector

Perovskite CsPbBr₃ semiconductors exhibit unusually high defect tolerance leading to outstanding and unique optoelectronic properties, demonstrating strong potential for γ-radiation and X-ray detection at room temperature. However, the total dose effects of the perovskite CsPbBr₃ must be considered when working in a long-term radiation environment. In this work, the Schottky type of perovskite CsPbBr₃ detector was fabricated. Their electrical characteristics and γ-ray response were investigated before and after ⁶⁰Co γ ray irradiation with 100 and 200 krad (Si) doses. The γ-ray response of the Schottky-type planar CsPbBr₃ detector degrades significantly with the increase in total dose. At the total dose of 200 krad(Si), the spectral resolving ability to γ-ray response of the CsPbBr₃ detector has disappeared. However, with annealing at room temperature for one week, the device's performance was partially recovered. Therefore, these results indicate that the total dose effects strongly influence the detector performance of the perovskite CsPbBr₃ semiconductor. Notably, it is concluded that the radiation-induced defects are not permanent, which could be mitigated even at room temperature. We believe this work could guide the development of perovskite detectors, especially under harsh radiation conditions.

A Dual-Kinetic Control Strategy for Designing Nano-Metamaterials: Novel Class of Metamaterials with Both Characteristic and Whole Sizes of Nanoscale

Increasingly intricate in their multilevel multiscale microarchitecture, metamaterials with unique physical properties are challenging the inherent constraints of natural materials. Their applicability in the nanomedicine field still suffers because nanomedicine requires a maximum size of tens to hundreds of nanometers; however, this size scale has not been achieved in metamaterials. Therefore, "nano-metamaterials," a novel class of metamaterials, are introduced, which are rationally designed materials with multilevel microarchitectures and both characteristic sizes and whole sizes at the nanoscale, investing in themselves remarkably unique and significantly enhanced material properties as compared with conventional nanomaterials. Microarchitectural regulation through conventional thermodynamic strategy is limited since the thermodynamic process relies on the frequency-dependent effective temperature, T_eff (ω), which limits the architectural regulation freedom degree. Here, a novel dual-kinetic control strategy is designed to fabricate nano-metamaterials by freezing a high-free energy state in a T_eff (ω)-constant system, where two independent dynamic processes, non-solvent induced block copolymer (BCP) self-assembly and osmotically driven self-emulsification, are regulated simultaneously. Fe³⁺ -"onion-like core@porous corona" (Fe³⁺ -OCPCs) nanoparticles (the products) have not only architectural complexity, porous corona and an onion-like core but also compositional complexity, Fe³⁺ chelating BCP assemblies. Furthermore, by using Fe³⁺ -OCPCs as a model material, a microstructure-biological performance relationship is manifested in nano-metamaterials.

Black-hole-inspired thermal trapping with graded heat-conduction metadevices

The curved space-time produced by black holes leads to the intriguing trapping effect. So far, metadevices have enabled analogous black holes to trap light or sound in laboratory spacetime. However, trapping heat in a conductive environment is still challenging because diffusive behaviors are directionless. Inspired by black holes, we construct graded heat-conduction metadevices to achieve thermal trapping, resorting to the imitated advection produced by graded thermal conductivities rather than the trivial solution of using insulation materials to confine thermal diffusion. We experimentally demonstrate thermal trapping for guiding hot spots to diffuse towards the center. Graded heat-conduction metadevices have advantages in energy-efficient thermal regulation because the imitated advection has a similar temperature field effect to the realistic advection that is usually driven by external energy sources. These results also provide an insight into correlating transformation thermotics with other disciplines, such as cosmology, for emerging heat control schemes.

Electronic structure and optical properties of doped γ-CuI scintillator: a first-principles study

A cuprous iodide (CuI) crystal is considered to be one of the inorganic scintillator materials with the fastest time response, which is expected to play an important role in the field of γ and X rays detection in the future. To improve the detection performance of the CuI scintillator, the effects of element doping on the electronic structure and optical properties of the γ-CuI were investigated by using the first principles calculation method. It was found that Li and Na doping increases the band gap of the γ-CuI scintillator, while Cs, F, Cl, and Br doping decreases the band gap. The optical absorption coefficient of the γ-CuI scintillator is decreased by the Li and Na doping, and the Cs, F, Cl, and Br doping has little effect on the optical absorption coefficient. The effects of the Tl doping on the electronic structure and optical properties of the γ-CuI scintillator depends on its concentration. Based on the changes in the electronic structure and optical properties, we conclude that the Cs, F, Cl, and Br doping might be a good method that can enhance the detection performance of the γ-CuI scintillator.

Element doping can affect the electronic structure and optical properties of γ-CuI. First principles calculations show that Cs, F, Cl, and Br doping may enhance the detection performance of γ-CuI scintillators.

Association between Intrinsic Capacity and Sarcopenia in Hospitalized Older Patients

OBJECTIVES

This study aimed to clarify the association between intrinsic capacity (IC) and sarcopenia in hospitalized older patients.

DESIGN

A cross-sectional study.

SETTING

Hospital-based.

PARTICIPANTS

This study included 381 inpatients aged ≥ 60 years (225 men and 156 women).

MEASUREMENTS

IC was evaluated in five domains defined by the World Health Organization: cognition (Mini-Mental State Examination), locomotion (Short Physical Performance Battery test), vitality (Short-Form Mini Nutritional Assessment), sensory (self-reported hearing and vision) and psychological (5-item Geriatric Depression Scale) capacities. IC composite score (0-5) was calculated based on five domains, with lower scores representing greater IC. Sarcopenia was defined in accordance with the criteria recommended by the Asian Working Group for Sarcopenia (AWGS) 2019. Multiple linear and logistic regressions were performed to explore the associations between IC composite score and IC domains with sarcopenia and its defining components.

RESULTS

The mean age of 381 patients included was 81.95±8.42 years. Of them, 128 (33.6%) patients had sarcopenia. The median IC composite score was 1 (1, 2). Cognition, locomotion, vitality, sensory and psychological capacities were impaired in 22.6%, 63.5%, 18.9%, 27.3% and 11.3% of patients. Multiple linear regression analyses showed that favorable IC domain scores in cognition, locomotion and vitality were associated with a stronger handgrip strength. A higher vitality score was associated with a greater appendicular skeletal muscle mass index (ASMI), and a higher locomotion score was associated with a greater gait speed. The multiple logistic regression analysis showed that only vitality impairment was associated with sarcopenia. A higher IC composite score was associated with higher risks of sarcopenia, as well as low ASMI, handgrip strength and gait speed.

CONCLUSION

This study indicated that a more serious impairment of IC was associated with a greater risk of sarcopenia. Vitality was the domain most strongly associated with sarcopenia. IC may be employed to detect and manage sarcopenia.

Microstructure and Mechanical Properties of As-Aged Mg-Zn-Sn-Mn-Al Alloys

The microstructure and mechanical properties of as-aged Mg-6Zn-4Sn-1Mn-xAl (ZTM641-xAl, x = 0, 0.2, 0.5, 1, 2, 3 and 4 wt.%) alloys are studied in this paper. In terms of microstructure, the results reveal that the addition of Al mainly leads to the formation of the Al₈Mn₅, Al₁₁Mn₄, Al₂Mg₅Zn₂ and Mg₃₂(Al,Zn)₄₉ phases. With increases in the addition of Al, the average grain size first decreases and then increases, while the undissolved phases increase. The average grain size of the ZTM641-0.5Al alloy is the smallest, and the single-aged and double-aged grain size is 14 μm and 12 μm, respectively. As for mechanical properties, with increases in the Al element, the strength decreases, and the elongation first increases and then decreases. The double-aged ZTM641-0.2Al alloy exhibits favorable mechanical properties at room temperature, and the UTS, YS and elongation are 384 MPa, 360 MPa and 9%, respectively. Further, the double-aged ZTM641-0.2Al alloy exhibits the comprehensive mechanical properties at 150 °C, that is, the UTS, YS and elongation are 212 MPa, 196 MPa and 29%, respectively, which is about 45% higher than that of the elongation of ZTM641. The ZTM641-xAl alloys exhibits mixed fracture at room temperature, and, with increases in the addition of Al, the fracture mechanisms of alloys are mixed fracture, ductile fracture and mixed fracture at 200 °C.

Locally Fluorinated Electrolyte Medium Layer for High-Performance Anode-Free Li-Metal Batteries

Low cycling Coulombic efficiency (CE) and messy Li dendrite growth problems have greatly hindered the development of anode-free Li-metal batteries (AFLBs). Thus, functional electrolytes for uniform lithium deposition and lithium/electrolyte side reaction suppression are desired. Here, we report a locally fluorinated electrolyte (LFE) medium layer surrounding Cu foils to tailor the chemical compositions of the solid-electrolyte interphase (SEI) in AFLBs for inhibiting the immoderate Li dendrite growth and to suppress the interfacial reaction. This LFE consists of highly concentrated LiTFSI dissolved in a fluoroethylene carbonate and/or succinonitrile plastic mixture. The CE of Cu||LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) AFLB increased to a high level of 99% as envisaged, and the cycling ability was also highly improved. These improvements are facilitated by the formation of a uniform, dense, and LiF-rich SEI. LiF possesses high interfacial energy at the LiF/Li interface, resulting in a more uniform Li deposition process as proved by density functional theory (DFT) calculation results. This work provides a simple yet utility tech for the enhancement of future high-energy-density AFLBs.

Study on Bone-like Microstructure Design of Carbon Nanofibers/Polyurethane Composites with Excellent Impact Resistance

It is a challenge to develop cost-effective strategy and design specific microstructures for fabricating polymer-based impact-resistance materials. Human shin bones require impact resistance and energy absorption mechanisms in the case of rapid movement. The shin bones are exciting biological materials that contain concentric circle structures called Haversian structures, which are made up of nanofibrils and collagen. The "soft and hard" structures are beneficial for dynamic impact resistance. Inspired by the excellent impact resistance of human shin bones, we prepared a sort of polyurethane elastomers (PUE) composites incorporated with rigid carbon nanofibers (CNFs) modified by elastic mussel adhesion proteins. CNFs and mussel adhesion proteins formed bone-like microstructures, where the rigid CNFs are served as the bone fibrils, and the flexible mussel adhesion proteins are regarded as collagen. The special structures, which are combined of hard and soft, have a positive dispersion and compatibility in PUE matrix, which can prevent cracks propagation by bridging effect or inducing the crack deflection. These PUE composites showed up to 112.26% higher impact absorbed energy and 198.43% greater dynamic impact strength when compared with the neat PUE. These findings have great implications for the design of composite parts for aerospace, army vehicles, and human protection.

Study on Mechanical Properties and High-Speed Impact Resistance of Carbon Nanofibers/Polyurethane Composites Modified by Polydopamine

Polyurethane elastomers (PUE), with superior mechanical properties and excellent corrosion resistance, are applied widely to the protective capability of structures under low-speed impact. However, they are prone to instantaneous phase transition, irreversible deformation and rupture even arising from holes under high-speed impact. In this paper, mussel adhesion proteins were applied to modify carbon nanofibers (CNFs) in a non-covalent way, and creatively mixed with PUE. This can improve the dispersity and interfacial compatibility of nanofillers in the PUE matrix. In addition, the homogeneous dispersion of modified nanofillers can serve as "reinforcing steel bars". The nanofillers and PUE matrix can form "mud and brick" structures, which show superb mechanical properties and impact resistance. Specifically, the reinforcement of 1.0 wt.% modified fillers in PUE is 103.51%, 95.12% and 119.85% higher than the neat PUE in compression modulus, storage modulus and energy absorption capability, respectively. The results have great implications in the design of composite parts for aerospace and army vehicles under extreme circumstances.

Cryogenic Scintillation Properties of Lead-Free Cs3Cu2I5 Single Crystals

Perovskite scintillators have become increasingly popular in recent years because of their simple production and high sensitivity to X-ray. Due to large Stokes shifts, high light yield, eco-friendly fabrication, and good stability, the lead-free Cu-based perovskites have gained much attention. In this paper, we prepared the Cs₃Cu₂I₅ single crystals (SCs) by the solution-processed method. At room temperature, we measured the emission band at 440 nm with an average decay time of 595 ns under X-ray excitation. Under ¹³⁷Cs γ-ray excitation, we determined that the light yield of Cs₃Cu₂I₅ SCs was 23 000 photons/MeV. Notably, under alpha particle excitation by ²⁴¹Am, the light yield of Cs₃Cu₂I₅ SCs is approximately 3.2 times higher than that of the commercial scintillator LYSO(Ce). In addition, we systematically investigated the cryogenic scintillation properties of Cs₃Cu₂I₅ SCs at the temperature range of 60-300 K. With decreasing temperature, the intensity of the emission band at 440 nm significantly increases, and an additional emission band at 336 nm emerges below 100 K. Meanwhile, the temperature-dependent decay times were determined. The fast and slow decay time of Cs₃Cu₂I₅ SCs are estimated to be 221 and 1193 ns, respectively, at 60 K. Our findings highlight the great potential for Cs₃Cu₂I₅ SCs to be a cryogenic scintillator.

The Effects of Different Anode Positions on the Electrical Properties of Square-Silicon Drift Detector

The Silicon Drift Detector (SDD) with square structure is often used in pixel-type SDD arrays to reduce the dead region considerably and to improve the detector performance significantly. Usually, the anode is located in the center of the active region of the SDD with square structure (square-SDD), but the different anode positions in the square-SDD active area are also allowed. In order to explore the effect on device performance when the anode is located at different positions in the square-SDD active region, we designed two different types of square-SDD in this work, where the anode is located either in the center (SDD-1) or at the edge (SDD-2) of its active region. The simulation results of current density and potential distribution show that SDD-1 and SDD-2 have both formed a good electron drift path to make the anode collect electrons. The experimental results of device performance at the temperature range from -60 °C to 60 °C show that the anode current of the two fabricated SDDs both decreased with the decrease of temperature, but their voltage divider characteristics exhibited high stability resistance value and low temperature coefficient, thereby indicating that they could both provide corresponding continuous and uniform electric field at different temperatures. Finally, SDD-1 and SDD-2 have energy resolutions of 248 and 257 eV corresponding to the 5.9 keV photon peak of the Fe-55 radioactive source, respectively. Our experimental results demonstrate that there is no significant impact on the device performance irrespective of the anode positions in the square-SDD devices.

Constructing robust polymer/two-dimensional Ti3C2TX solid-state electrolyte interphase via in-situ polymerization for high-capacity long-life and dendrite-free lithium metal anodes

We constructed an artificial polymer/two-dimensional Ti₃C₂T_X (MXene) solid electrolyte interphase (SEI) on a Li metal surface via an in-situ polymerization strategy. The polymer layer provides excellent interface contact and outstanding adaptability for the volume expansion of Li metal, decreasing interface impedance. On the other hand, the two-dimensional MXene with a low Li nucleation energy barrier is beneficial for uniform Li deposition and restraint of interfacial side reactions. In this work, a dense and durable MXene-integrated SEI between the Li metal anode and solid-state electrolyte (SSE) interface is constructed to render the Li/SSE/Li cell to maintain a stable polarization voltage of approximately 50 mV at a capacity of 0.50 mAh cm^-2 for over 1000 h. It enables the Li/SSE/LiFePO₄ cell to deliver a capacity of 130.1 mAh g^-1 at 1C with a capacity retention of 91.4% after 900 cycles. Therefore, we believe that this facile in-situ polymerization method for constructing a layer of polymer/MXene SEI at the interface between Li metal anodes and SSE can promote the practical applications of Li metal batteries.

Theory-Guided Regulation of FeN4 Spin State by Neighboring Cu Atoms for Enhanced Oxygen Reduction Electrocatalysis in Flexible Metal-Air Batteries

Iron, nitrogen-codoped carbon (Fe-N-C) nanocomposites have emerged as viable electrocatalysts for the oxygen reduction reaction (ORR) due to the formation of FeN_x C_y coordination moieties. In this study, results from first-principles calculations show a nearly linear correlation of the energy barriers of key reaction steps with the Fe magnetic moment. Experimentally, when single Cu sites are incorporated into Fe-N-C aerogels (denoted as NCAG/Fe-Cu), the Fe centers exhibit a reduced magnetic moment and markedly enhanced ORR activity within a wide pH range of 0-14. With the NCAG/Fe-Cu nanocomposites used as the cathode catalyst in a neutral/quasi-solid aluminum-air and alkaline/quasi-solid zinc-air battery, both achieve a remarkable performance with an ultrahigh open-circuit voltage of 2.00 and 1.51 V, large power density of 130 and 186 mW cm^-2 , and good mechanical flexibility, all markedly better than those with commercial Pt/C or Pt/C-RuO₂ catalysts at the cathode.

Surface Wettability for Skin-Interfaced Sensors and Devices

The practical applications of skin-interfaced sensors and devices in daily life hinge on the rational design of surface wettability to maintain device integrity and achieve improved sensing performance under complex hydrated conditions. Various bio-inspired strategies have been implemented to engineer desired surface wettability for varying hydrated conditions. Although the bodily fluids can negatively affect the device performance, they also provide a rich reservoir of health-relevant information and sustained energy for next-generation stretchable self-powered devices. As a result, the design and manipulation of the surface wettability are critical to effectively control the liquid behavior on the device surface for enhanced performance. The sensors and devices with engineered surface wettability can collect and analyze health biomarkers while being minimally affected by bodily fluids or ambient humid environments. The energy harvesters also benefit from surface wettability design to achieve enhanced performance for powering on-body electronics. In this review, we first summarize the commonly used approaches to tune the surface wettability for target applications toward stretchable self-powered devices. By considering the existing challenges, we also discuss the opportunities as a small fraction of potential future developments, which can lead to a new class of skin-interfaced devices for use in digital health and personalized medicine.

Cryogenic Scintillation Performance of Cs4PbI6 Perovskite Single Crystals

All-inorganic Cs₄PbI₆ single crystals (SCs) is emerging scintillators for radiation detection. In this study, we report on the X-ray scintillation properties of Cs₄PbI₆ SCs at the temperature range of 50-290 K. The temperature-dependent radioluminescence (RL) spectrum and decay time were investigated. It was found that the RL spectra show very pronounced temperature-dependent changes in the overall shape. The RL intensity increases with a decrease in the temperature under X-ray excitation. The emission bands at 318, 360, and 554 nm are attributed to the near-band-edge emission in Cs₄PbI₆ SCs, the ³P₁ → ¹S₀ transition of the Pb²⁺ ion, and the emission of δ-CsPbI₃ aggregates dispersed in the Cs₄PbI₆ SC matrix, respectively. With decreasing temperature, the fast and slow decay times tend to slow down and are estimated to be 46.0 ns (33.22%) and 820 ns (66.78%) at 50 K, which are far superior to that of the common cryogenic scintillator. These cryogenic scintillation characteristics of Cs₄PbI₆ SCs demonstrate its potential for cryogenic detection.

Tribological Behaviors of Super-Hard TiAlN Coatings Deposited by Filtered Cathode Vacuum Arc Deposition

High hardness improves the material’s load-bearing capacity, resulting in the enhancement of tribological properties. However, the high hardness is difficult to achieve for TiAlN coating due to the transformation of the close-packed structure from cubic to hexagonal and the increase in the grain size when the Al content is high. In the present study, the ultrahard TiAlN coatings (hardness > 40 GPa) are successfully developed by filtered cathodic vacuum arc technology to study the effect of nitrogen flux rate on tribological behaviors. The highest hardness of 46.39 GPa is obtained by tuning the nitrogen flux rate to achieve the regulation of Al content and the formation of nanocrystalline. The stable fcc TiAlN phase is formed via the solid-phase reaction under a high nitrogen concentration, and more aluminum atoms replace the titanium atoms in the (Ti, Al)N solid solution. The high Al content of the Ti0.35Al0.65N coating has a nanocrystalline structure and the average crystalline size is 16.52 nm. The TiAlN coating deposited at a nitrogen flux rate of 60 sccm exhibits the best properties of a combination of microhardness = 2972.91 Hv0.5, H = 46.39 GPa, E = 499.4 Gpa, ratio H/E* = 0.093 and ratio H3/E*2 = 0.403. Meanwhile, the TiAlN coating deposited at 60 sccm shows the lowest average friction coefficient of 0.43 and wear rate of 1.3 × 10−7 mm3 N−1 m−1 due to the best mechanical properties.

Moisture-resistant MXene-sodium alginate sponges with sustained superhydrophobicity for monitoring human activities

Wearable mechanical sensors are easily influenced by moisture resulting in inaccuracy for monitoring human health and body motions. Though the superhydrophobic barrier has been extensively explored as passive water repel strategy on the sensor surface, the dense superhydrophobic surface not only limits the sensor working under large deformations but also inevitable degradation in high humidity or saturation water vapor environments. This work reports a superhydrophobic MXene-sodium alginate sponge (SMSS) pressure sensor with a low voltage Joule heating effect to provide sustain moisture-insensitive property for both sensing performance and superhydrophobicity by heating-driven water molecules away. Because of the positive temperature coefficient under pressure applied, the Joule heating can provides a stable temperature to the moisture-insensitivity property during the whole dynamic pressure cycled. Therefore, the pressure sensor with a simple spray-coating superhydrophobic coating on the outer layer demonstrates key capabilities even in extreme use scenarios with high humidity or water vapor and also provides stable and reliable bio-signal monitoring.

Anomalous Blue Shift of Exciton Luminescence in Diamond

Generally speaking, for a semiconductor, the temperature dependence of excitonic emission corresponds to that of its band gap. However, an anomalous behavior is exhibited by the excitonic luminescence of diamond where as the temperature increases (from 10 to 300 K), its indirect exciton luminescence peak displays a spectral-distinguishable blue shift, whereas the indirect band-gap absorption shows a weak red shift. According to experimental high-resolution deep-ultraviolet spectra and theoretical analysis, the weak red shift of its indirect band gap is ascribed to its large Debye temperature (Θ_D ≈ 2220 K), which makes the lattice constant change comparatively little in a large temperature range, so the change of its band gap is relatively small; in this case, as the temperature rises, the thermal population of valence-band holes that moves to a high-energy state far away from the Fermi surface contributes to the macroscopic blue shift of its excitonic emission.

SGTools: a suite of tools for processing and analyzing large data sets from in situ X-ray scattering experiments

In situ synchrotron small-angle X-ray scattering (SAXS) is a powerful tool for studying dynamic processes during material preparation and application. The processing and analysis of large data sets generated from in situ X-ray scattering experiments are often tedious and time consuming. However, data processing software for in situ experiments is relatively rare, especially for grazing-incidence small-angle X-ray scattering (GISAXS). This article presents an open-source software suite (SGTools) to perform data processing and analysis for SAXS and GISAXS experiments. The processing modules in this software include (i) raw data calibration and background correction; (ii) data reduction by multiple methods; (iii) animation generation and intensity mapping for in situ X-ray scattering experiments; and (iv) further data analysis for the sample with an order degree and interface correlation. This article provides the main features and framework of SGTools. The workflow of the software is also elucidated to allow users to develop new features. Three examples are demonstrated to illustrate the use of SGTools for dealing with SAXS and GISAXS data. Finally, the limitations and future features of the software are also discussed.