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In order to achieve high-quality welding of titanium copper dissimilar metals, the in-situ remelting welded joints of TC4 and T2 were obtained by using a time-sharing dual electron beam(TDEB). A welded joint consisting of the IMCs layer, FZ zone, copper weld zone, and titanium side HAZ is formed in the TC4/T2 interface area. The microstructure and morphology of IMCs layers in welded joints with TDEB welding and copper offset welding were observed by using SEM and TEM. Multiple forms of IMCs were observed in the IMCs layer, including columnar Ti2Cu, granular Ti3Cu4, and sheet-like TiCu4, clarifying the orientation relationship between some precipitates and matrix phases. The TC4/T2 joint welded with TDEB welding achieved micro zone remelting of the IMCs layer. The thickness of the IMCs layer has significantly decreased, and the number of copper-rich phases in the IMCs layer has increased, which improves the mechanical properties of the welded joint. The TC4/T2 joint welded by time-sharing dual beam electron beam has a tensile strength of 215.9 MPa and an elongation of 6.14%. The joint exhibits brittle quasi dissociation fracture. The main factor causing fracture is the high brittleness and hardness of titanium-rich phases such as TiCu and Ti2Cu. This study provide a new welding method for titanium copper dissimilar metals, as well as research ideas for dissimilar metal welding.

The poor interface of silicon carbide (SiC)/SiO2 combined with the short channel effects (SCEs) and source contact resistance, collectively impacts the effective threshold voltage in SiC MOSFETs. In this work, a physical discrete channel model was proposed to analyze the influence of the combined effects of varying channel lengths, as well as applied drain and gate voltages. The proposed model was validated through TCAD simulation and by the fabricated SiC power MOSFETs. This model was applicable to MOSFETs with both symmetric and asymmetric channels considering various interface state density distributions. The influence of these factors on effective threshold voltage was also discussed considering variations in source contact resistance and channel doping concentration. Through the analysis of the model results, it was found that the interface states significantly impact the effective threshold voltage through different mechanisms while the SCEs are mitigated by the unsaturated interface states.

Two new polymorphs (forms VIII and IX) of piroxicam were discovered through poly(ethylene glycol) (PEG)-assisted melt crystallization, and their structures were revealed by 3D electron diffraction (3D ED). This discovery provides insight into the potential of PEG in pharmaceutical polymorph discovery and verifies the significance of 3D ED as an essential technique for structural determination of pharmaceuticals. Furthermore, the direct contribution of intermolecular hydrogen bonding to melting points was discussed based on the structural divergency between the newly solved form VIII and the previously reported form IV. Combining PEG-assisted melt crystallization and 3D ED not only accelerated the discovery of new polymorphs but also provided unique opportunities for understanding structure–property relationships in pharmaceutical crystals.

Recent neural rendering methods have made great progress in generating photorealistic human avatars. However, these methods are generally conditioned only on low-dimensional driving signals (e.g., body poses), which are insufficient to encode the complete appearance of a clothed human. Hence they fail to generate faithful details. To address this problem, we exploit driving view images (e.g., in telepresence systems) as additional inputs. We propose a novel neural rendering pipeline, Hybrid Volumetric-Textural Rendering (HVTR++), which synthesizes 3D human avatars from arbitrary driving poses and views while staying faithful to appearance details efficiently and at high quality. First, we learn to encode the driving signals of pose and view image on a dense UV manifold of the human body surface and extract UV-aligned features, preserving the structure of a skeleton-based parametric model. To handle complicated motions (e.g., self-occlusions), we then leverage the UV-aligned features to construct a 3D volumetric representation based on a dynamic neural radiance field. While this allows us to represent 3D geometry with changing topology, volumetric rendering is computationally heavy. Hence we employ only a rough volumetric representation using a pose- and image-conditioned downsampled neural radiance field (PID-NeRF), which we can render efficiently at low resolutions. In addition, we learn 2D textural features that are fused with rendered volumetric features in image space. The key advantage of our approach is that we can then convert the fused features into a high-resolution, high-quality avatar by a fast GAN-based textural renderer. We demonstrate that hybrid rendering enables HVTR++ to handle complicated motions, render high-quality avatars under user-controlled poses/shapes, and most importantly, be efficient at inference time. Our experimental results also demonstrate state-of-the-art quantitative results.

In this article, a structure design concept plasma spreading layer (PSL) has been introduced into planar silicon carbide (SiC) MOSFETs. Devices’ static characteristics, gate–drain capacitance ( ${C}_{\text {gd}}{)}$ , and short-circuit (SC) robustness are studied with experiments. The PSL structure can increase the breakdown voltage (BV) and reduce ${C}_{\text {gd}}$ of the devices. The MOSFETs with the PSL exhibit an 11.6% higher Baliga’s figure of merit (BFOM) and a 75% higher 1/high-frequency figures-of-merit (HF-FOM). Moreover, they have better SC robustness by 60%, 67%, and 33% under 400-, 600-, and 800-V dc bus voltage than that of the traditional one. Combined with the experimental data and the 3-D simulation results, the MOSFETs with the PSL have enhanced JFET effects, which reduces the electric potential, SC current density, and electric field in the JFET region during the SC process, so as to enhance the SC robustness. The SC failure mechanisms are studied with emission microscope (EMMI) analysis, focused ion beam (FIB) observation, and simulations.

The fluid kinematics of Liutex decomposes a velocity gradient tensor (VGT) of ∇vinto four components, including rotation (R), stretching/compressing (SC), anti-symmetric shear (Santi-sym) and symmetric shear (Ssym), as oppose to the traditional Cauchy-Stokes decomposition where a VGT was decomposed into the strain rate and vorticity tensors. The current study limpidly clarified the physical meanings of these deformations in the newly-proposed decomposition from the perspectives of both fluid kinematics and dynamics. With in-depth understanding the physical connotations of these deformations, the present study further suggests that the Ssymbe the only deformation appropriately correlated to the stress tensor, leading to the establishment of a new constitutive relation for Newtonian fluids with the modified model assumptions originated from Stokes in 1845. Moreover, the present research finds that the “principal decomposition” proposed by Liu is not mathematically unique when a VGT has three real eigenvalues (TR). Within the context, a new decomposition method is introduced to avoid the non-uniqueness issue arising from using the principal decomposition to establish fluid dynamics equations. Based on the modified Stokes assumptions and the novel VGT decomposition method, a set of new fluid dynamics momentum equations are obtained for Newtonian fluid. The added stress tensor of Faddis identified as the key difference between the newly-derived governing equations and the conventional Navier-Stokes (N-S) equations, which is caused by excluding the SCcorrelation to the stress tensor in the new constitutive equation. Finally, a preliminary analysis of Faddis conducted using the existing channel turbulence direct numerical simulations (DNS) data based on the traditional N-S equations. The Faddis found widely existing in turbulence and is of the same order of magnitude with the other force terms. Therefore, the Faddis expected to have some nonnegligible effects on altering the current DNS data based on the traditional N-S equations, which will be further verified by performing the “DNS” simulation using the newly-derived fluid dynamics equations in near future.

In this work, 1200 V SiC JMOS devices with different Wsch (2 μm, 2.5 μm and 3 μm) are fabricated. The single unclamped inductive switching (UIS) tests under different Vgs_off (-5 V and 0 V) are carried out to investigate the avalanche capability. The avalanche robustness among various Wsch under same Vgs_off is also compared and analyzed by simulation. The different failure mechanisms between different Vgs_off are studied by failure analysis and simulation. The method of improving avalanche ruggedness of JMOS is proposed.

The controllable packing of functional nanoparticles (NPs) into crystalline lattices is of interest in the development of NP-based materials. Here we demonstrate that the size, morphology and symmetry of such supercrystals can be tailored by adjusting the surface dynamics of their constituent NPs. In the presence of excess tetraethylammonium cations, atomically precise [Au25(SR)18]−NPs (where SR is a thiolate ligand) can be crystallized into micrometre-sized hexagonal rod-like supercrystals, rather than as face-centred-cubic superlattices otherwise. Experimental characterization supported by theoretical modelling shows that the rod-like crystals consist of polymeric chains in which Au25NPs are held together by a linear SR–[Au(I)–SR]4interparticle linker. This linker is formed by conjugation of two dynamically detached SR–[Au(I)–SR]2protecting motifs from adjacent Au25particles, and is stabilized by a combination of CH⋯πand ion-pairing interactions between tetraethylammonium cations and SR ligands. The symmetry, morphology and size of the resulting supercrystals can be systematically tuned by changing the concentration and type of the tetraalkylammonium cations.

Continuous-rotation 3D electron diffraction methods are increasingly popular for the structure analysis of very small organic molecular crystals and crystalline inorganic materials. Dynamical diffraction effects cause non-linear deviations from kinematical intensities that present issues in structure analysis. Here, a method for structure analysis of continuous-rotation 3D electron diffraction data is presented that takes multiple scattering effects into account. Dynamical and kinematical refinements of 12 compounds—ranging from small organic compounds to metal–organic frameworks to inorganic materials—are compared, for which the new approach yields significantly improved models in terms of accuracy and reliability with up to fourfold reduction of the noise level in difference Fourier maps. The intrinsic sensitivity of dynamical diffraction to the absolute structure is also used to assign the handedness of 58 crystals of 9 different chiral compounds, showing that 3D electron diffraction is a reliable tool for the routine determination of absolute structures.

In this article, the influence of the JFET width and JFET doping concentration on the 1.2-kV planar-gate silicon carbide (SiC) MOSFETs’ static characteristics, ${C}$ – ${V}$ characteristics, and short-circuit (SC) reliability is discussed. With the increase of the JFET width, the specific ON-resistance decreases first and then increases (but the quasi-saturated current continues to increase), the blocking voltage decreases, and the reverse capacitance increases. The SC tests under 400-V dc bus voltage are carried out to compare the SC capability of the devices. With the increase of the JFET width, the SC peak current first increases and then decreases, and the SC withstanding time keeps decreasing. The increase of peak current is due to the weaker electric field shielding effect by the P-well. With the further increase of the JFET width, the peak current decreases because the depletion layer appears in the middle position of the JFET region below the gate oxide and the channel density decreases with the wider JFET width. Compared with the winner of the traditional design, the winner with enhanced JFET doping is preferred because it achieves an increased Baliga’s figure of merit (BFOM) by 15.9% and 1/high-frequency figure of merit (HF-FOM) by 84.2% without sacrificing too much SC reliability, which is more competitive.

In this work, the influences of P-well design and turn-off gate-to-source bias on the surge robustness of SiC MOSFET’s body diode are studied. Devices with high and low P-well doping concentration designs are stressed with surge current pulses when the gate-to-source is biased with 0 or −5 V. The gate-to-source bias is found to have effects on the surge capability of the low P-well doping-designed device. In the case of 0-V bias, the channel is prone to turning on and acquires a higher surge capability than the devices under the −5 V. On the other hand, the surge capability of high P-well doping-designed device is found less influenced by the gate-to-source bias. Furthermore, threshold voltage instability after repetitive surge pulses is also investigated. The device with low P-well doping shows better threshold stability due to its lower interface trap density. Based on the results above, a design methodology is proposed from the view of device mechanism and operation condition. Relatively low P-well doping design and negative gate bias are recommended for SiC MOSFET, as they can improve the single-pulse surge robustness of body diode and minimize the threshold voltage instability in repetitive surge pulse events.

Metal–organic frameworks (MOFs) have attracted considerable interest due to their well-defined pore architecture and structural tunability on molecular dimensions. While single-crystal X-ray diffraction (SCXRD) has been widely used to elucidate the structures of MOFs at the atomic scale, the formation of large and well-ordered crystals is still a crucial bottleneck for structure determination. To alleviate this challenge, three-dimensional electron diffraction (3D ED) has been developed for structure determination of nano- (submicron-)sized crystals. Such 3D ED data are collected from each single crystal using transmission electron microscopy. In this protocol, we introduce the entire workflow for structural analysis of MOFs by 3D ED, from sample preparation, data acquisition and data processing to structure determination. We describe methods for crystal screening and handling of crystal agglomerates, which are crucial steps in sample preparation for single-crystal 3D ED data collection. We further present how to set up a transmission electron microscope for 3D ED data acquisition and, more importantly, offer suggestions for the optimization of data acquisition conditions. For data processing, including unit cell and space group determination, and intensity integration, we provide guidelines on how to use electron and X-ray crystallography software to process 3D ED data. Finally, we present structure determination from 3D ED data and discuss the important features associated with 3D ED data that need to be considered. We believe that this protocol provides critical details for implementing and utilizing 3D ED as a structure determination platform for nano- (submicron-)sized MOFs as well as other crystalline materials.

In the study of framework materials, probing interactions between frameworks and organic molecules is one of the most important tasks, which offers us a fundamental understanding of host–guest interactions in gas sorption, separation, catalysis, and framework structure formation. Single-crystal X-ray diffraction (SCXRD) is a conventional method to locate organic species and study such interactions. However, SCXRD demands large crystals whose quality is often vulnerable to, e.g., cracking on the crystals by introducing organic molecules, and this is a major challenge to use SCXRD for structural analysis. With the development of three-dimensional electron diffraction (3D ED), single-crystal structural analysis can be performed on very tiny crystals with sizes on the nanometer scale. Here, we analyze two framework materials, SU-8 and SU-68, with organic molecules inside their inorganic crystal structures. By applying 3D ED, with fast data collection and an ultralow electron dose (0.8–2.6 e–Å–2), we demonstrate for the first time that each nonhydrogen atom from the organic molecules can be ab initio located from structure solution, and they are shown as distinct and well-separated peaks in the difference electrostatic potential maps showing high accuracy and reliability. As a result, two different spatial configurations are identified for the same guest molecule in SU-8. We find that the organic molecules interact with the framework through strong hydrogen bonding, which is the key to immobilizing them at well-defined positions. In addition, we demonstrate that host–guest systems can be studied at room temperature. Providing high accuracy and reliability, we believe that 3D ED can be used as a powerful tool to study host–guest interactions, especially for nanocrystals.

In this paper, we propose and compare two novel deep generative model-based approaches for the design representation, reconstruction, and generation of porous metamaterials characterized by complex and fully connected solid and pore networks. A highly diverse porous metamaterial database is curated, with each sample represented by solid and pore phase graphs and a voxel image. All metamaterial samples adhere to the requirement of complete connectivity in both pore and solid phases. The first approach employs a dual decoder variational graph autoencoder to generate both solid phase and pore phase graphs. The second approach employs a variational graph autoencoder for reconstructing/generating the nodes in the solid phase and pore phase graphs and a transformer-based large language model (LLM) for reconstructing/generating the connections, i.e., the edges among the nodes. A comparative study was conducted, and we found that both approaches achieved high accuracy in reconstructing node features, while the LLM exhibited superior performance in reconstructing edge features. Reconstruction accuracy is also validated by voxel-to-voxel comparison between the reconstructions and the original images in the test set. Additionally, discussions on the advantages and limitations of using LLMs in metamaterial design generation, along with the rationale behind their utilization, are provided.

In this work, third-quadrant $I$ – $V$ characterization and surge current tests are carried out on SiC asymmetric-trench MOSFET (DUT A) and SiC double-trench MOSFET (DUT B) under various gate–source biases ( $V_{\mathrm {GS}}$ ). The surge capability is found to be uninfluenced by $V_{\mathrm {GS}}$ for DUT A. However, it has a 71.4% increase when $V_{\mathrm {GS}}$ changes from 0 to −5 V for DUT B. The $I$ – $V$ characteristics in the third quadrant are measured under various $V_{\mathrm {GS}}$ . It is found that the channel is open when the source–drain voltage is >2.5 V for DUT A and >1.5 V for DUT B at $V_{\mathrm {GS}} =0$ V. High-temperature measurements are also conducted from 298 K to 448 K. When $V_{\mathrm {GS}} =0$ V, the channel current takes up to 50% at 10-A source-to-drain current for DUT B, whereas only 10% for DUT A. This could lead to high current/heat density in the channel of DUT B. The transient resistance is also extracted from the surge $I$ – $V$ trajectories, and it is higher for DUT B tested under $V_{\mathrm {GS}} =0$ V, which will increase the dissipated surge energy. Finally, the failure mechanism is analyzed. For DUT A, aluminum melting contributes to the failure at $V_{\mathrm {GS}}= -5$ V and $V_{\mathrm {GS}} =0$ V. For DUT B tested at $V_{\mathrm {GS}} =0$ V, the earlier breakdown happens due to gate oxide failure.

The structure of the novel medium-pore borosilicate zeolite EMM-25 has been determined by continuous rotation electron diffraction (cRED). EMM-25 crystallizes in the space group Cmcmwith unit cell parameters a= 11.055, b= 22.912, and c= 24.914 Å and a composition of |C4H8(C11H25N)2|2[Si112.5B3.5O232]. The EMM-25 framework possesses a two-dimensional channel system composed of 10-ring channels connected via 11-ring windows. Its channel system is analogous to that of the medium-pore zeolite NU-87 framework but with 11- rather than 12-ring windows, suggesting a different shape selectivity. EMM-25 was first obtained using 1,4-bis(N-methyl-N,N-dihexylammonium)butane as an organic structure directing agent (OSDA). Based on a molecular docking study of the OSDA within the pores of the determined framework structure, a new ammonium dication OSDA with an improved fit was devised. By using this new OSDA, the synthesis time was reduced 80%, from 52 to just 10 days. Furthermore, cRED data revealed a structural disorder of the EMM-25 framework present as swinging zigzag chains. The introduction of the disorder, which is a consequence of geometry relaxation, was crucial for an accurate structure refinement. Lastly, the cRED data from as-made EMM-25 showed residual potential consistent with the location of the OSDA position determined from the Rietveld refinement, concluding a complete refinement of the as-made structure based on the cRED data.

Amorphous ice is commonly used as a noncrystalline matrix for protecting sensitive biological samples in cryogenic electron microscopy (cryo-EM). The amorphization process of water is complex, and at least two amorphous states of different densities are known to exist, high- and low-density amorphous ices (HDA and LDA). These forms are considered to be the counterparts of two distinct liquid states, namely, high- and low-density liquid water. Herein, we investigate the HDA to LDA transition using electron diffraction and cryo-EM. The observed phase transition is induced by the impact of electrons, and we discuss two different mechanisms, namely, local heating and beam-induced motion of water molecules. The temperature increase is estimated by comparison with X-ray scattering experiments on identically prepared samples. Our results suggest that HDA, under the conditions used in our cryo-EM measurements, is locally heated above its glass-transition temperature.

A new layered mesoporous Zr-MOF of composition [Zr30O20(OH)26(OAc)18L18] was synthesized by employing 5-acetamidoisophthalic acid (H2L) using acetic acid as the solvent. The new MOF, denoted as CAU-45, exhibits a honeycomb structure of stacked layers which comprise both hexa- and dodecanucelar zirconium clusters. Its structure was solved from submicrometer-sized crystals by continuous rotation electron diffraction (cRED). Liquid phase exfoliation and size selection were successfully performed on the material.

The oxygen reduction reaction (ORR) is central in carbon-neutral energy devices. While platinum group materials have shown high activities for ORR, their practical uses are hampered by concerns over deactivation, slow kinetics, exorbitant cost, and scarce nature reserve. The low cost yet high tunability of metal–organic frameworks (MOFs) provide a unique platform for tailoring their characteristic properties as new electrocatalysts. Herein, we report a new concept of design and present stable Zr-chain-based MOFs as efficient electrocatalysts for ORR. The strategy is based on using Zr-chains to promote high chemical and redox stability and, more importantly, tailor the immobilization and packing of redox active-sites at a density that is ideal to improve the reaction kinetics. The obtained new electrocatalyst, PCN-226, thereby shows high ORR activity. We further demonstrate PCN-226 as a promising electrode material for practical applications in rechargeable Zn-air batteries, with a high peak power density of 133 mW cm–2. Being one of the very few electrocatalytic MOFs for ORR, this work provides a new concept by designing chain-based structures to enrich the diversity of efficient electrocatalysts and MOFs.

Lithium-alloyable materials such as Ge and P have attracted considerable attention as promising anode materials for lithium-ion batteries (LIBs) owing to their high theoretical capacity. However, these materials inevitably undergo capacity attenuation caused by large volume expansion in repeated electrochemical processes. Herein, we propose a facile strategy to synthesize germanium–phosphorus binary nanoparticles embedded in porous carbon (GPBN/C) via metallothermic reduction. As an LIB anode, the GPBN/C electrode exhibits outstanding rate performance (368 mAh g–1at 40 A g–1) and remarkable long-term cycling ability (541 mAh g–1at 1.0 A g–1after 1000 cycles). Besides, the GPBN/C composite electrode presents an outstanding cycling performance at wide temperature ranges, showing reversible capacities of 1030 and 696 mAh g–1at 60 and 0 °C, respectively. Attributed to the formation of highly dispersed Ge–P nanoparticles in a porous carbon matrix, the GPBN/C electrode shows exceptional electrochemical performance. Importantly, our strategy provides an effective way to explore alloy-type electrodes to develop fast and stable high-capacity batteries.

A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride (g-C3N4) nanosheets for CO2reduction via coupling with the electron donor Co-metal-organic framework (MOF) is proposed in this study. Specifically, Co-MOF as an electron donor is capable of transferring the photogenerated electrons in the lowest unoccupied molecular orbital (LUMO) to the conduction band of g-C3N4to facilitate charge separation. As expected, the prepared Co-MOF/g-C3N4nanocomposites display excellent visible-light-driven photocatalytic CO2reduction activities. The CO production rate of 6.75 µmol g−1h−1and CH4evolution rate of 5.47 µmol g−1h−1are obtained, which are approximately 2 times those obtained with the original g-C3N4under the same conditions. Based on a series of analyses, it is shown that the introduction of Co-MOF not only broadens the range of visible-light absorption but also enhances the charge separation, which improves the photocatalytic activity of g-C3N4to a higher level. In particular, the hydroxyl radical (•OH) experiment was operated under 590 nm (single-wavelength) irradiation, which further proved that the photogenerated electrons in the LUMO of Co-MOF can successfully migrate to g-C3N4. This work may provide an important strategy for the design of highly efficient g-C3N4-based photocatalysts for CO2reduction.

Five novel bismuth carboxylate coordination polymers were synthesized from biphenyl-3,4′,5-tricarboxylic acid (H3BPT) and [1,1′:4′,1′′]terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4TPTC). One of the phases, [Bi(BPT)]·2MeOH (denoted SU-100, as synthesized), is the first example, to the best of our knowledge, of a reversibly flexible bismuth-based metal–organic framework. The material exhibits continuous changes to its unit cell parameters and pore shape depending on the solvent it is immersed in and the dryness of the sample. Typically, in breathing carboxylate-based MOFs, flexibility occurs through tilting of the organic linkers without significantly altering the coordination environment around the cation. In contrast to this, the continuous breathing mechanism in SU-100 involves significant changes to bond angles within the Bi2O12inorganic building unit (IBU). The flexibility of the IBU of SU-100 reflects the nondiscrete coordination geometry of the bismuth cation. A disproportionate increase in the solvent accessible void volume was observed when compared to the expansion of the unit cell volume of SU-100. Additionally, activated SU-100 (SU-100-HT) exhibits a large increase in unit cell volume, yet has the smallest void volume of all the studied samples.

Threshold voltage and channel mobility of a 1.2-kV planar-channel SiC MOSFET at high junction temperature (Ti) up to 700 °C have been extracted and analyzed for the first time, by virtue of a specially designed short-circuit (SC) measurement technique we developed. Under the SC condition, Ti of the SiC MOSFET can rise significantly within a few microseconds, which can be extracted based on the SC waveforms and thermal calculations. The planar-channel SiC MOSFET investigated in this work can maintain normally-off operation at an elevated Ti up to 700 °C. Furthermore, the underlying mechanisms of the temperature dependence of the threshold voltage and channel mobility are also analyzed. The threshold voltage of the SiC MOSFET exhibits a different temperature dependence over a wide range (120-700 °C) compared with that of Si counterparts, which is attributed to interface traps' response. The channel mobility shows a non-monotonic temperature dependence, due to divergent scattering mechanisms.

Lithium-nickel-manganese-cobalt-oxides (NMC) embedded in solid-electrolytes are being extensively applied as composite cathodes to match the high energy density of metallic anodes. During charge/discharge, the cathode composite often degrades through the evolution of micro-cracks within the grains, along the grain boundaries, and delamination at the particle-electrolyte interface. Experimental evidence has shown that regulating the morphology of grains and their crystallographic orientations is an effective way to relieve the volume-expansion-induced stresses and cracks, consequently stabilizing the electrochemical performance of the electrode. However, the interplay among the crystal orientation, grain morphology, and chemo-mechanical behavior has not been holistically studied. In that context, a thermodynamically consistent computational framework is developed to understand the role of microstructural modulation on the chemo-mechanical interactions of a polycrystalline NMC secondary particle embedded in a sulfide-based solid electrolyte. A phase-field fracture variable is employed to consider the initiation and propagation of cracks. A set of diffused phase-field parameters is adopted to define the transition of chemo-mechanical properties between the grains, grain boundaries, electrolyte, and particle-electrolyte interfaces. This modeling framework is implemented in the open-source finite element package MOOSE to solve three state variables: concentration, displacement, and phase-field damage parameter. A systematic parametric study is performed to explore the effects of aspect ratio, the crystal orientation of grains, and the interfacial fracture energy through the chemo-mechanical analysis of the composite electrode. The findings of this study offer predictive insights for designing solid-state batteries that provide stable performance with reduced fracture evolution.

Metal–organic frameworks (MOFs) based on Ti-oxo clusters (Ti-MOFs) represent a naturally self-assembled superlattice of TiO2nanoparticles separated by designable organic linkers as antenna chromophores, epitomizing a promising platform for solar energy conversion. However, despite the vast, diverse, and well-developed Ti-cluster chemistry, only a scarce number of Ti-MOFs have been documented. The synthetic conditions of most Ti-based clusters are incompatible with those required for MOF crystallization, which has severely limited the development of Ti-MOFs. This challenge has been met herein by the discovery of the [Ti8Zr2O12(COO)16] cluster as a nearly ideal building unit for photoactive MOFs. A family of isoreticular photoactive MOFs were assembled, and their orbital alignments were fine-tuned by rational functionalization of organic linkers under computational guidance. These MOFs demonstrate high porosity, excellent chemical stability, tunable photoresponse, and good activity toward photocatalytic hydrogen evolution reactions. The discovery of the [Ti8Zr2O12(COO)16] cluster and the facile construction of photoactive MOFs from this cluster shall pave the way for the development of future Ti-MOF-based photocatalysts.

Lithium metal anode is considered to be a promising candidate for high-energy-density lithium-based batteries. However, the safety issue induced by uncontrollable dendrite growth hinders the commercialization of a Li anode. Herein, self-supported three-dimensional flexible carbon cloth covered with a lithiophilic silicon nanowire array is constructed as the host for loading of molten Li to achieve the C/SiNW/Li composite anode. The electrode component of the carbon cloth provides the flexible and conductive substrate to accommodate the volume change during the stripping/plating of Li and facilitate more efficient electron transport, while silicon nanowires improve the wettability of the carbon host to liquefied Li and render uniform Li deposition on the surface of the composite electrode. The as-prepared C/SiNW/Li composite anode exhibits enhanced cycling stability with a low hysteresis of 40 mV for more than 200 h and a better rate tolerance even at a current density of up to 5 mA cm–2. When coupling with the LiNi0.5Mn1.5O4cathode, the full cells using the C/SiNW/Li composite anode demonstrate a remarkable electrochemical performance with an exceptional rate performance of up to 10 C and stable long-term cycling (the capacity retention of 62% at a 5 C rate over 2000 cycles), which is much higher than the cells with pure Li anode. This work provides a universal strategy to fabricate the flexible and stable carbon-based Li metal anode toward high-energy-density batteries.

A new aluminosilicate zeolite, denoted EMM-37, with a 3D small pore channel system, has been synthesized using a diquaternary ammonium molecule as the structure directing agent (SDA) and metakaolin as the aluminum source. The structures of both as-madeand calcined forms of EMM-37 were solved and refined using continuous rotation electron diffraction (cRED) data. cRED is a powerful method for the collection of 3D electron diffraction data from submicron- and nanosized crystals, which allows for successful solution and refinement of complex structures in symmetry as low as P1̅.

As a milestone research in vortex identification (VI), the physical quantity of Liutex, including its forms of scalar, vector and tensor, was systematically explored and rigorously obtained as the third-generation (3G) of the vortex definition and identification methods distinguished from the first generation (1G) by vorticity and the second generation (2G) by the vortex identification (VI) criteria solely dependent on the velocity gradient tensor eigenvalues. Based on these findings, the vortex-core lines were abstracted from the well-defined Liutex, and for the first time, were automatically generated and massively visualized using computer. The distinctive characteristics of these vortex cores with the intriguing threshold-independency make them be the uniquely appropriate entity to represent and to depict the vortex structures in turbulence. The letter made use of the DNS data for the natural transition in a zero-pressure gradient flat-plate (Type-A turbulent boundary layer (TBL)) and the fully-developed turbulence in a square annular duct (Type-B TBL) to demonstrate the vortex structure represented by the vortex-core lines. The 3G VI approach based on the vortex-core lines is capable of profoundly uncovering the vortex natures. Moreover, the capability of automatically identifying the vortex cores and massively visualizing the large number of vortex-core behaviors in a transient way will enable the fluid-mechanics and other related-science communities to step into a new era to explore the intrinsic natures of the centennial puzzle of turbulence and other vortex-related phenomena in future.

Aluminum-based metal–organic frameworks (MOFs), [Al(OH)(SDC)]n, (H2SDC: 4,4′-stilbenedicarboxylic acid), also known as CYCU-3, were prepared by means of the coordination modulation method to produce materials with different crystal size and morphology. In particular, we screened several reagent concentrations (20–60 mM) and modulator/ligand ratios (0–50), leading to 20 CYCU x_ymaterials (x: reagent concentration, y= modulator/ligand ratio) with different particle size and morphology. Noteworthy, the use of high modulator/ligand ratio gives rise to a new phase of CYCU-3 (CYCU-3′ x_50 series), which was structurally analyzed. Afterward, to test the potential of these materials as CO-prodrug carriers, we selected three of them to adsorb the photo- and bioactive CO-releasing molecule (CORM) ALF794 [Mo(CNCMe2CO2H)3(CO)3] (CNCMe2CO2H = 2-isocyano-2-methyl propionic acid): (i) CYCU-3 20_0, particles in the nanometric range; (ii) CYCU-3 50_5, bar-type particles with heterogeneous size, and (iii) CYCU-3′ 50_50, a new phase analogous to pristine CYCU-3. The corresponding hybrid materials were fully characterized, revealing that CYCU-3 20_0 with the smallest particle size was not stable under the drug loading conditions. Regarding the other two materials, similar ALF794 loadings were found (0.20 and 0.19 CORM/MOF molar ratios for ALF794@CYCU-3 50_5 and ALF794@CYCU-3′ 50_50, respectively). In addition, these hybrid systems behave as CO-releasing materials (CORMAs), retaining the photoactive properties of the pristine CORM in both phosphate saline solution and solid state. Finally, the metal leaching studies in solution confirmed that ALF794@CYCU-3′ 50_50 shows a good retention capacity toward the potentially toxic molybdenum fragments (75% of retention after 72 h), which is the lowest value reported for a MOF-based CORMA to date.

Wide bandgap SiC and GaN power devices are attractive for next-generation power electronic systems with increased efficiency and power density. In this paper, we review recent progress in SiC and GaN power devices, including the following. (1) Interface optimization techniques for SiC MOSFETs (e.g. NO/N2O annealing, P incorporation, metal interfacial-layer, high-k dielectric deposition, etc.) will be discussed. (2) Long-term reliability of SiC MOSFETs with special focus on time-dependent dielectric breakdown (TDDB) will be presented. (3) We will introduce our latest progress in the development of superjunction SiC devices, which can break the fundamental limit of the conventional unipolar devices. (4) In GaN-based lateral power devices, the 2DEG channel is an inherent normally-on channel. To achieve fail-safe operation and simpler gate drive circuit, normally-off device techniques will be introduced and compared.

With the development of superlubricity, the requirement for the accuracy of measuring super low friction force becomes more and more high. In this study, a novel micro-tribometer has been designed. The resolution and accuracy of friction force are 0.01 mN by using the dual frequency laser interferometer. Experiments were performed to investigate the ability of measuring friction force from different aspects. The interference signal mixed in the measured friction force curve was analyzed and can be removed by a designed filter. The results of experiment show that the tribometer is capable of measuring a super low friction force in the order of magnitude of 0.01 mN with an applied load up to 1 N.

We experimentally demonstrate that textured open metal surfaces, i.e., the ultrathin fan-shaped metallic strips, are able to support spoof localized surface plasmons (spoof-LSPs) in the microwave frequencies. Unlike conventional spoof-LSPs supported on textured closed metal surfaces, which originate from the interference of clockwise and counterclockwise propagating surface modes, spoof-LSPs on textured open metal surfaces arise from the Fabry–Perot-like resonances due to the terminations of the open surfaces. We show that both the number of modes and the resonance frequencies of spoof-LSPs on textured open metal surfaces can be engineered through tuning the grating numbers (or total length) of the structured fan-shaped metallic strip. This enables the tuning of the spoof-plasmonic resonator by simply changing its length, rather than the complete geometry, simplifying the design to just one degree of freedom. Experimental evidence of the spoof-LSP Fabry–Perot resonators in the microwave regimes is presented with near-field response spectra and mode profiles imaged directly.

The model of ideal fluid flow around a cylindrical obstacle exhibits a long-established physical picture, where originally straight streamlines are deflected over the whole space by the obstacle. Inspired by transformation optics and metamaterials, recent theories have proposed the concept of fluid cloaking, which is able to recover the straight streamlines, as if the obstacle did not exist. However, such a cloak, similar to all previous transformation-optics-based devices, relies on complex metamaterials with inhomogeneous parameters and is difficult to implement. Here we deploy the theory of scattering cancellation and report on the experimental realization of a fluid-flow cloak without metamaterials. This cloak is realized by engineering the geometry of the fluid channel, which effectively cancels the dipole-like scattering of the obstacle. The cloaking effect is demonstrated through the direct observation of recovered straight streamlines in the fluid flow. Our work sheds new light on conventional fluid control and may find application in microfluidic devices.By judiciously engineering the geometry of the fluid channel, an `invisibility' cloak able to make an object undetectable from fluid flow is realized experimentally.

The reaction mechanism of the oxidation of cyclohexanone catalyzed by titanium silicate zeolite TS-1 using aqueous H2O2as the oxidant was investigated by combining density function theory (DFT) calculations with experimental studies. DFT calculations showed that H2O2was adsorbed and activated at the tetrahedral Ti sites. By taking into account the adsorption energy, molecular size, steric hindrance and structural information, a reaction mechanism of Baeyer-Villiger oxidation catalyzed by TS-1 that involves the activation of H2O2was proposed. Experimental studies showed that the major products of cyclohexanone oxidation by H2O2catalyzed by a hollow TS-1 zeolite were ɛ-carprolactone, 6-hydroxyhexanoic acid, and adipic acid. These products were analyzed by GC-MS and were in good agreement with the proposed mechanism. Our studies showed that the reaction mechanism on TS-1 zeolite was different from that on Sn-beta zeolite.