Suppressed thermal transport in silicon nanoribbons by inhomogeneous strain.

Nanoscale structures can produce extreme strain that enables unprecedented material properties, such as tailored electronic bandgap1-5, elevated superconducting temperature6,7 and enhanced electrocatalytic activity8,9. While uniform strains are known to elicit limited effects on heat flow10-15, the impact of inhomogeneous strains has remained elusive owing to the coexistence of interfaces16-20 and defects21-23. Here we address this gap by introducing inhomogeneous strain through bending individual silicon nanoribbons on a custom-fabricated microdevice and measuring its effect on thermal transport while characterizing the strain-dependent vibrational spectra with sub-nanometre resolution. Our results show that a strain gradient of 0.112% per nanometre could lead to a drastic thermal conductivity reduction of 34 ± 5%, in clear contrast to the nearly constant values measured under uniform strains10,12,14,15. We further map the local lattice vibrational spectra using electron energy-loss spectroscopy, which reveals phonon peak shifts of several millielectron-volts along the strain gradient. This unique phonon spectra broadening effect intensifies phonon scattering and substantially impedes thermal transport, as evidenced by first-principles calculations. Our work uncovers a crucial piece of the long-standing puzzle of lattice dynamics under inhomogeneous strain, which is absent under uniform strain and eludes conventional understanding.

Measuring phonon dispersion at an interface.

The breakdown of translational symmetry at heterointerfaces leads to the emergence of new phonon modes localized at the interface1. These modes have an essential role in thermal and electrical transport properties in devices, especially in miniature ones wherein the interface may dominate the entire response of the device2. Although related theoretical work began decades ago1,3-5, experimental research is totally absent owing to challenges in achieving the combined spatial, momentum and spectral resolutions required to probe localized modes. Here, using the four-dimensional electron energy-loss spectroscopy technique, we directly measure both the local vibrational spectra and the interface phonon dispersion relation for an epitaxial cubic boron nitride/diamond heterointerface. In addition to bulk phonon modes, we observe modes localized at the interface and modes isolated from the interface. These features appear only within approximately one nanometre around the interface. The localized modes observed here are predicted to substantially affect the interface thermal conductance and electron mobility. Our findings provide insights into lattice dynamics at heterointerfaces, and the demonstrated experimental technique should be useful in thermal management, electrical engineering and topological phononics.

Atomic-Scale Mechanism of Enhanced Electron-Phonon Coupling at the Interface of MgB2 Thin Films.

In conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, electron-phonon coupling is the fundamental mechanism of superconductivity. For instance, the superconductivity of magnesium diboride (MgB2) comes from the coupling between E2g modes (in-plane boron-boron bond vibrations) and self-doped charge carriers. In thin films and ceramics of BCS superconductors, interfaces with discontinuous chemical bonds may alter the local electron-phonon coupling. However, such effects remain largely unexplored. Here, we investigate the heterointerface of the MgB2 film on the SiC substrate at the atomic scale using electron microscopy and spectroscopy. We detect the presence of a thin MgO layer with a thickness of ∼1 nm between MgB2 and SiC. Atomic-level electron energy loss spectra (EELS) show MgB2-E2g mode splitting and softening near the MgB2/MgO interface, which enhances electron-phonon coupling at the interface. Our findings highlight the potential of interface engineering to enhance superconductivity via modulating local phonon states and/or electron states.

Superior radiation tolerance via reversible disordering-ordering transition of coherent superlattices.

Materials capable of sustaining high radiation doses at a high temperature are required for next-generation fission and future fusion energy. To date, however, even the most promising structural materials cannot withstand the demanded radiation environment due to irreversible radiation-driven microstructure degradation. Here we report a counterintuitive strategy to achieve exceptionally high radiation tolerance at high temperatures by enabling reversible local disordering-ordering transition of the introduced superlattice nanoprecipitates in metallic materials. As particularly demonstrated in martensitic steel containing a high density of B2-ordered superlattices, no void swelling was detected even after ultrahigh-dose radiation damage at 400-600 °C. The reordering process of the low-misfit superlattices in highly supersaturated matrices occurs through the short-range reshuffling of radiation-induced point defects and excess solutes right after rapid, ballistic disordering. This dynamic process stabilizes the microstructure, continuously promotes in situ defect recombination and efficiently prevents the capillary-driven long-range diffusion process. The strategy can be readily applied into other materials and pave the pathway for developing materials with high radiation tolerance.

Rising Drug Resistance Among Gram-Negative Pathogens in Bloodstream Infections: A Multicenter Study in Ulanhot, Inner Mongolia (2017-2021).

BACKGROUND Bloodstream infections, which arise when pathogenic microorganisms infiltrate the bloodstream, present a grave health risk. Their potentially lethal nature combined with the ability to severely impair physiological functions underscore the importance of understanding and mitigating such infections. This study aimed to elucidate drug sensitivity profiles and distribution of these pathogens in hospitals in Ulanhot, Inner Mongolia. MATERIAL AND METHODS From 2017 to 2021, we gathered blood culture-positive samples from several hospitals across Ulanhot. Using combined diagnostic techniques, including the instrument method, paper diffusion, and Epsilometer test (E-test), we determined the identity of pathogens and assessed their drug sensitivity. Subsequent data processing with WHONET 5.6 software provided insights into the patterns of microbial distribution and extent of drug resistance. RESULTS Of 2498 pathogenic strains identified, 35.83% were gram-positive, 62.45% were gram-negative, and a smaller fraction of 1.72% were fungi. Escherichia coli and Klebsiella pneumoniae were the primary bacteria, contributing to 35.15% and 15.73% of infections, respectively. Alarmingly, methicillin-resistant strains exhibited pronounced resistance to drugs, notably penicillin G (resistance rates of 80.87% to 100.00%) and erythromycin (resistance rates of 91.16% to 97.28%). Acinetobacter baumannii had a particularly high resistance profile, surpassing Pseudomonas aeruginosa, which exhibited a resistance rate below 30.00%. CONCLUSIONS Ulanhot's primary bloodstream infection agents were gram-negative bacteria, specifically E. coli and K. pneumoniae. The growing drug resistance observed, particularly among strains like A. baumannii, highlights the pressing need for rigorous drug resistance surveillance and the strategic use of antibiotics, ensuring their efficacy is preserved for future medical needs.

Plan quality and treatment efficiency assurance of two VMAT optimization for cervical cancer radiotherapy.

To investigate the difference of the fluence map optimization (FMO) and Stochastic platform optimization (SPO) algorithm in a newly-introduced treatment planning system (TPS). METHODS: 34 cervical cancer patients with definitive radiation were retrospectively analyzed. Each patient has four plans: FMO with fixed jaw plans (FMO-FJ) and no fixed jaw plans (FMO-NFJ); SPO with fixed jaw plans (SPO-FJ) and no fixed jaw plans (SPO-NFJ). Dosimetric parameters, Modulation Complexity Score (MCS), Gamma Pass Rate (GPR) and delivery time were analyzed among the four plans. RESULTS: For target coverage, SPO-FJ plans are the best ones (P ≤ 0.00). FMO plans are better than SPO-NFJ plans (P ≤ 0.00). For OARs sparing, SPO-FJ plans are better than FMO plans for mostly OARs (P ≤ 0.04). Additionally, SPO-FJ plans are better than SPO-NFJ plans (P ≤ 0.02), except for rectum V45Gy. Compared to SPO-NFJ plans, the FMO plans delivered less dose to bladder, rectum, colon V40Gy and pelvic bone V40Gy (P ≤ 0.04). Meanwhile, the SPO-NFJ plans showed superiority in MU, delivery time, MCS and GPR in all plans. In terms of delivery time and MCS, the SPO-FJ plans are better than FMO plans. FMO-FJ plans are better than FMO-NFJ plans in delivery efficiency. MCSs are strongly correlated with PCTV length, which are negatively with PCTV length (P ≤ 0.03). The delivery time and MUs of the four plans are strongly correlated (P ≤ 0.02). Comparing plans with fixed or no fixed jaw in two algorithms, no difference was found in FMO plans in target coverage and minor difference in Kidney_L Dmean, Mu and delivery time between PCTV width≤15.5 cm group and >15.5 cm group. For SPO plans, SPO-FJ plans showed more superiority in target coverage and OARs sparing than the SPO-NFJ plans in the two groups. CONCLUSIONS: SPO-FJ plans showed superiority in target coverage and OARs sparing, as well as higher delivery efficiency in the four plans.

Electron Microscopy Probing Electron-Photon Interactions in SiC Nanowires with Ultrawide Energy and Momentum Match.

Light-matter interactions are commonly probed by optical spectroscopy, which, however, has some fundamental limitations such as diffraction-limited spatial resolution, tiny momentum transfer, and noncontinuous excitation/detection. In this work, through the use of scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) with ultrawide energy and momentum match and subnanometer spatial resolution, the longitudinal Fabry-Perot (FP) resonating modes and the transverse whispering-gallery modes (WGMs) in individual SiC nanowires are simultaneously excited and detected, which span from near-infrared (∼1.2 µm) to ultraviolet (∼0.2 µm) spectral regime, and the momentum transfer can range up to 108 cm-1. The size effects on the resonant spectra of nanowires are also revealed. This work provides an alternative technique to optical resonating spectroscopy and light-matter interactions in dielectric nanostructures, which is promising for modulating free electrons via photonic structures.

Long Non-coding RNA GAS5/miR-520-3p/SOCS3 Axis Regulates Inflammatory Response in Lipopolysaccharide-Induced Macrophages.

Sepsis is mainly caused by infection, and inflammation plays a vital role in the progression of sepsis. Increasing evidence shows the regulatory mechanism of long non-coding RNA growth arrest-specific 5 (GAS5) in inflammatory response. However, the potential role of GAS5 in sepsis was not really clear. Here, we set to investigate the role and mechanism of GAS5 in the inflammatory response of lipopolysaccharide (LPS)-induced macrophages in vitro. Levels of GAS5, microRNA-520-3p, suppressor of cytokine signaling 3 (SOCS3) and inflammatory cytokines tumor necrosis factor-α (TNF-α), and interleukin (IL)-6 and IL-1ß were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Nitric oxide (NO) release was measured through flow cytometry. The levels of TNF-α, IL-6, and IL-1ß were also detected using ELISA. Dual-luciferase reporter and RNA pull-down assays were performed to clarify the relationship between miR-520-3p and GAS5 or SOCS3. Western blot was carried out to assess SOCS3 protein expression in macrophages. GAS5 level was remarkably decreased in sepsis serum and it was inversely related to the severity of sepsis. Upregulation of GAS5 repressed inflammatory response in LPS-induced macrophages, and the inhibitory effect was returned by miR-520-3p mimics. Moreover, miR-520-3p inhibitor downregulated the levels of inflammatory factors of TNF-α, IL-6, and IL-1ß, as well as suppressed NO release. Mechanically, GAS5 functioned as a sponge of miR-520-3p and miR-520-3p directly targeted SOCS3. GAS5 regulated inflammatory response by the miR-520-3p/SOCS3 axis in LPS-induced macrophages, which furnished a novel therapeutic idea in clinical treatment of inflammation-induced sepsis.

LncRNA-RMRP promotes nucleus pulposus cell proliferation through regulating miR-206 expression.

Long noncoding RNAs (LncRNAs) are involved in the pathogenesis of intervertebral disc degeneration (IDD). However, the biological function and expression of RMRP were still unclear. In our study, we showed that RMRP expression was up-regulated in degenerated NP tissues compared to normal NP samples, and higher RMRP expression was associated with the disc degeneration grade. Further studies indicated that ectopic expression of RMRP enhanced NP cell growth and also enhanced the expression of ki-67, PCNA and cyclin D1 in the NP cell. Moreover, overexpression of RMRP promoted the expression of Type II collagen and aggrecan and suppressed the expression of MMP13 and ADAMTS4. In addition, we found that the expression of miR-206 was down-regulated in degenerated NP tissues compared to normal NP samples, and lower miR-206 expression was correlated with the disc degeneration grade. Interestingly, we indicated that miR-206 expression in NP tissues was negatively correlated with the expression of RMRP. Ectopic expression of miR-206 suppressed NP cell proliferation and suppressed the expression of Type II collagen and aggrecan and enhanced the expression of MMP13 and ADAMTS4. Furthermore, we demonstrated that overexpression of RMRP increased NP cell growth and regulated ECM expression through targeting miR-206. These results suggested that lncRNA-RMRP promoted the progression of IDD through targeting miR-206, providing an attractive new therapeutic approach for the treatment of IDD disease.

miR-423-5p Inhibits Osteosarcoma Proliferation and Invasion Through Directly Targeting STMN1.

BACKGROUND/AIMS: Increasing evidences suggest that dysregulated expression of miRNAs contributes to the progression of various tumors. However, the underlying function of miR-423-5p in osteosarcoma remains unexplored. METHODS: The expression of miR-423-5p and STMN1 were determined in osteosarcoma samples and cell lines via quantitative real-time PCR. Colony formation and Cell Counting Kit-8 (CCK-8) assays were performed to measure cell proliferation ability and transwell analysis was used to detect cell invasion, and dual luciferase reporter assay was perform to analysis the interaction between the miR-423-5p and STMN1. RESULTS: The expression levels of miR-423-5p and STMN1 in the osteosarcoma tissues and cell lines were measured by qRT-PCR. Cell viability was determined using the clone formation and CCK-8 assays. A dual-luciferase reporter and Western blot were performed to stdudy the target gene of miR-423-5p. Here, we showed that miR-423-5p expression was downregulated in osteosarcoma tissues and cell lines. However, the expression of stathmin1 (STMN1) was downregulated in osteosarcoma tissues and cell lines. Moreover, STMN1 expression level was negatively correlated with the miR-423-5p expression in the osteosarcoma tissues. We identified STMN1 was a direct target gene of miR-423-5p in osteosarcoma cell. Overexpression of miR-423-5p inhibited osteosarcoma cell proliferation, colony formation and invasion. Furthermore, we demonstrated that STMN1 was involved in miR-423-5p-mediated cell behavior such as cell proliferation, colony formation and invasion in the osteosarcoma cell. CONCLUSION: Our present study indicated that miR-423-5p acted as a tumor suppressor gene in osteosarcoma partly through inhibiting STMN1 expression.

Structures and luminescent sensors of mixed-counterions based salen-type lanthanide coordination polymers.

Reactions of N,N'-bis (salicylidene)-1,2-cyclohexanediamine (H2 L) with mixed lanthanide counterions of LnCl3 ·6H2 O and Ln (NO3 )3 ·6H2 O afford six H2 L lanthanide coordination polymers, e.g. {[Pr(H2 L)2 (NO3 )2 Cl]·2CH2 Cl2 }n (1); {[Ln(H2 L)1.5 (NO3 )3 ]2 ·5CHCl3 ·mCH3 OH}n [Ln = Sm (2), Eu (3), Gd (4), Tb (5) and Yb (6); m = 1 (2-5); m = 0 (6)]. X-ray crystallographic analysis reveals that complex 1 exhibits three-dimensional diamondoid topologic structure and complexes 2-6 are of two-dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near-infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2-5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.

Detwinning through migration of twin boundaries in nanotwinned Cu films under in situ ion irradiation.

The mechanism of radiation-induced detwinning is different from that of deformation detwinning as the former is dominated by supersaturated radiation-induced defects while the latter is usually triggered by global stress. In situ Kr ion irradiation was performed to study the detwinning mechanism of nanotwinned Cu films with various twin thicknesses. Two types of incoherent twin boundaries (ITBs), so-called fixed ITBs and free ITBs, are characterized based on their structural features, and the difference in their migration behavior is investigated. It is observed that detwinning during radiation is attributed to the frequent migration of free ITBs, while the migration of fixed ITBs is absent. Statistics shows that the migration distance of free ITBs is thickness and dose dependent. Potential migration mechanisms are discussed.

Synthesis of core-shell structured FAU/SBA-15 composite molecular sieves and their performance in catalytic cracking of polystyrene.

Composite molecular sieves, FAU/SBA-15, having core-shell structure were synthesized. The synthesized composite sieves were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), pyrolysis fourier transform infrared (Py-FTIR) spectroscopy, temperature programmed desorption spectra (NH3-TPD), UV Raman spectroscopy, nuclear magnetic resonance (NMR) and other techniques. XRD, SEM, TEM, N2 adsorption-desorption, mass spectrometry, NMR and EDS results showed that the composite molecular sieve contained two pore channels. Py-FTIR results showed that the addition of HY molecular sieves improved the acidity of the composite zeolite. The crystallization mechanism during the growth of FAU/SBA-15 shell was deduced from the influence of crystallization time on the synthesis of FAU/SBA-15 core-shell structured composite molecular sieve. HY dissociated partially in H2SO4 solution, and consisted of secondary structural units. This framework structure was more stable than its presence in the isolated form on the same ring or in the absence of Al. Thus it played a guiding role and connected with SBA-15 closely through the Si-O bond. This resulted in the gradual covering of the exterior surface of FAU phase by SBA-15 molecular sieves. The presence of SBA-15 restricted the formation of the other high mass components and increased the selectivity towards ethylbenzene.

Meningitis in a Chinese adult patient caused by Mycoplasma hominis: a rare infection and literature review.

BACKGROUND: Mycoplasma hominis, a well known cause of neonatal infection, has been reported as a pathogen in urogenital infections in adults; however, central nervous system (CNS) infections are rare. We report here the first case of M. hominis meningitis in China, post neurosurgical treatment for an intracerebral haemorrhage in a 71-year-old male. CASE PRESENTATION: We describe a 71-year-old man who developed M. hominis meningitis after neurosurgical treatment and was successfully treated with combined azithromycin and minocycline therapy of 2 weeks duration, despite delayed treatment because the Gram stain of cerebrospinal fluid (CSF) yielded no visible organisms. The diagnosis required 16S rDNA sequencing analysis of the cultured isolate from CSF. Literature review of M. hominis CNS infections yielded 19 cases (13 instances of brain abscess, 3 of meningitis, 1 spinal cord abscess and 1 subdural empyema each). Delay in diagnosis and initial treatment failure was evident in all cases. With appropriate microbiological testing, antibiotic therapy (ranging from 5 days to 12 weeks) and often, multiple surgical interventions, almost all the patients improved immediately. CONCLUSIONS: Both our patient findings and the literature review, highlighted the pathogenic potential of M. hominis together with the challenges prompted by rare infectious diseases in particular for developing countries laboratories with limited diagnostic resources.

[Sesquiterpenes from stems of Schisandra henryi var. henryi].

The dried stems of Schisandra henryi var. henryi were extracted with 95% ethanol and the extracts were further subjected to partition, affording the ethyl acetate extracts(EtOAc Extrs.).The EtOAc Extrs.were separated and purified with silica gel and octadecyl-silylated silica gel column chromatography, preparative HPLC and preparative TLC. Thirteen known compounds were obtained and identified by spectral methods including MS and NMR, all of which were elucidated as t-cadinol(1), cadinane-4ß,5α,10ß-triol(2), cadinane-5α, 10α-diol-2-ene(3), oxyphyllenodiols A(4), 1ß, 4ß-dihydroxyeudesman-11-ene(5), cyperusol C(6), (7R)-opposit-4(15)-ene-1ß,7-diol(7), dysodensiol E(8), epi-guaidiol A(9), aromadendrane-4ß,10ß-diol(10), tricyclohumuladiol(11), caryolane-1,9ß-diol(12), and guaidiol A(13). Compounds 3, 5-10, and 13 were separated from the genus for the first time, while compounds 1-13 were separated from this species for the first time.

Accelerated marine carbon cycling forced by tectonic degassing over the Miocene Climate Optimum.

Global warming during the Miocene Climate Optimum (MCO, ∼17-14 million years ago) is associated with massive carbon emissions sourced from the flood basalt volcanism and ocean crustal production. However, the perturbation of tectonic carbon degassing on the interaction between climate change and carbon cycle remains unclear. Here, through time-evolutive phase analysis of new and published high-resolution benthic foraminiferal oxygen (δ18O) and carbon (δ13C) isotope records from the global ocean, we find that variations in the marine carbon cycle lead the climate-cryosphere system (δ13C-lead-δ18O) on 405,000-year eccentricity timescales during the MCO. This is in contrast to the previously reported climate-lead-carbon (δ18O-lead-δ13C) scenario during most of the Oligo-Miocene (∼34-6 million years ago). Further sensitivity analysis and model simulations suggest that the elevated atmospheric CO2 concentrations and the resulting greenhouse effect strengthened the low-latitude hydrological cycle during the MCO, accelerating the response of marine carbon cycle to eccentricity forcing. Tropical climate processes played a more important role in regulating carbon-cycle variations when Earth's climate was in a warm regime, as opposed to the dominant influence of polar ice-sheet dynamics during the Plio-Pleistocene (after ∼6 million years ago).

Machine learning-based ensemble prediction model for the gamma passing rate of VMAT-SBRT plan.

PURPOSE: The purpose of this study was to accurately predict or classify the beam GPR with an ensemble model by using machine learning for SBRT(VMAT) plans. METHODS: A total of 128 SBRT VMAT plans with 330 arc beams were retrospectively selected, and 216 radiomics and 34 plan complexity features were calculated for each arc beam. Three models for GPR prediction and classification using support vector machine algorithm were as follows: (1) plan complexity feature-based model (plan model); (2) radiomics feature-based model (radiomics model); and (3) an ensemble model combining the two models (ensemble model). The prediction performance was evaluated by calculating the mean absolute error (MAE), root mean square error (RMSE), and Spearman's correlation coefficient (SC), and the classification performance was measured by calculating the area under the receiver operating characteristic curve (AUC), accuracy, specificity, and sensitivity. RESULTS: The MAE, RMSE and SC at the 2 %/2 mm gamma criterion in the test dataset were 1.4 %, 2.57 %, and 0.563, respectively, for the plan model; 1.42 %, and 2.51 %, and 0.508, respectively, for the radiomics model; and 1.33 %, 2.49 %, and 0.611, respectively, for the ensemble model. The accuracy, specificity, sensitivity, and AUC at the 2 %/2 mm gamma criterion in the test dataset were 0.807, 0.824, 0.681, and 0.854, respectively, for the plan model; 0.860, 0.893, 0.624, and 0.877, respectively, for the radiomics model; and 0.852, 0.871, 0.710, and 0.896, respectively, for the ensemble model. CONCLUSIONS: The ensemble model can improve the prediction and classification performance for the GPR of SBRT (VMAT).

Atomic-scale observation of localized phonons at FeSe/SrTiO3 interface.

In single unit-cell FeSe grown on SrTiO3, the superconductivity transition temperature features a significant enhancement. Local phonon modes at the interface associated with electron-phonon coupling may play an important role in the interface-induced enhancement. However, such phonon modes have eluded direct experimental observations. The complicated atomic structure of the interface brings challenges to obtain the accurate structure-phonon relation knowledge. Here, we achieve direct characterizations of atomic structure and phonon modes at the FeSe/SrTiO3 interface with atomically resolved imaging and electron energy loss spectroscopy in an electron microscope. We find several phonon modes highly localized (~1.3 nm) at the unique double layer Ti-O terminated interface, one of which (~ 83 meV) engages in strong interactions with the electrons in FeSe based on ab initio calculations. This finding of the localized interfacial phonon associated with strong electron-phonon coupling provides new insights into understanding the origin of superconductivity enhancement at the FeSe/SrTiO3 interface.

Probing Hyperbolic Shear Polaritons in ß-Ga2O3 Nanostructures Using STEM-EELS.

Phonon polaritons, quasiparticles arising from strong coupling between electromagnetic waves and optical phonons, have potential for applications in subdiffraction imaging, sensing, thermal conduction enhancement, and spectroscopy signal enhancement. A new class of phonon polaritons in low-symmetry monoclinic crystals, hyperbolic shear polaritons (HShPs), have been verified recently in ß-Ga2O3 by free electron laser (FEL) measurements. However, detailed behaviors of HShPs in ß-Ga2O3 nanostructures still remain unknown. Here, by using monochromatic electron energy loss spectroscopy in conjunction with scanning transmission electron microscopy, the experimental observation of multiple HShPs in ß-Ga2O3 in the mid-infrared (MIR) and far-infrared (FIR) ranges is reported. HShPs in various ß-Ga2O3 nanorods and a ß-Ga2O3 nanodisk are excited. The frequency-dependent rotation and shear effect of HShPs reflect on the distribution of EELS signals. The propagation and reflection of HShPs in nanostructures are clarified by simulations of electric field distribution. These findings suggest that, with its tunable broad spectral HShPs, ß-Ga2O3 is an excellent candidate for nanophotonic applications.

Four-dimensional electron energy-loss spectroscopy.

Recent advances in scanning transmission electron microscopy have enabled atomic-scale focused, coherent, and monochromatic electron probes, achieving nanoscale spatial resolution, meV energy resolution, sufficient momentum resolution, and a wide energy detection range in electron energy-loss spectroscopy (EELS). A four-dimensional EELS (4D-EELS) dataset can be recorded with a slot aperture selecting the specific momentum direction in the diffraction plane and the beam scanning in two spatial dimensions. In this paper, the basic principle of the 4D-EELS technique and a few examples of its application are presented. In addition to parallelly acquired dispersion with energy down to a lattice vibration scale, it can map the real space variation of any EELS spectrum features with a specific momentum transfer and energy loss to study various locally inhomogeneous scattering processes. Furthermore, simple mathematical combinations associating the spectra at different momenta are feasible from the 4D dataset, e.g., the efficient acquisition of a reliable electron magnetic circular dichroism (EMCD) signal is demonstrated. This 4D-EELS technique provides new opportunities to probe the local dispersion and related physical properties at the nanoscale.