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In order to demonstrate the application of terahertz time-domain ellipsometry (THz-TDE) in the characterization of wide-bandgap semiconductors, we studied two zinc oxide (ZnO) single crystals with different conductivities. The optical properties of ZnO samples with low conductivity and high conductivity are both obtained by ellipsometric parameters, while the electrical properties of ZnO sample with high conductivity are well deduced and fitted using the Drude model. These results suggest that THz-TDE can effectively obtain the optical and electrical properties of wide-gap semiconductors and can be used to characterize semiconductors with carrier densities higher than 1016 cm−3.

Efficient terahertz sources with controllable characteristics such as frequency range and polarization state are being rapidly researched and developed to suit various practical applications. To address this need, we realized the idea of combining micro- and nano-sized materials by fabricating micrometer-scale split-ring resonators made of a metal nanostructured film. We found that the peak frequencies of the emitted terahertz waves are in good correspondence with the terahertz resonance frequencies of the split-ring resonators. A possible mechanism is that a surge current was induced inside the split-ring resonators as a result of photoexcitation with the help of plasmon resonance around nanostructures, and the induced current emitted terahertz waves reflecting the resonance properties of the split-ring resonators. Although the silver nanostructures constituting the rings are random and homogeneous, the induction of the current parallel to the sample surface is enabled by the oblique incidence excitation, which breaks the symmetry along the sample surface. The present study shows the possibility of making compact terahertz emitters with flexibly tunable spectral shape, potentially leading to the development of terahertz sources optimized for specific spectroscopic uses.

Background and purposeDespite the ongoing advancements in mechanical thrombectomy for large vessel occlusions causing acute ischemic stroke, successful recanalization is not achieved in all patients. One contributing factor is the presence of fibrin-rich hard clots. We proposed a new technique called the PREMIER technique, which aims to retrieve fibrin-rich clots. This study evaluated the efficacy of the PREMIER technique on fibrin-rich and erythrocyte-rich clots by comparing it with the simple use of EmboTrap III in an in vitro vessel model.MethodsThe PREMIER technique involves partially resheathing a fully deployed EmboTrap III (CERENOVUS, Johnson & Johnson Medical Devices, Irvine, California, USA) using a microcatheter to capture and retrieve a hard clot between the inner channel and outer cages of EmboTrap III. We compared recanalization rate of the PREMIER technique with the simple use of EmboTrap III in an in vitro vessel model, occluding the M1 segment with fibrin-rich hard clots (0% erythrocyte composition) and erythrocyte-rich clots (50% erythrocyte composition).ResultsAmong the 40 procedures (10 each for the PREMIER technique and the simple use of EmboTrap III for two different clots) for fibrin-rich clots, the PREMIER technique achieved successful recanalization in all 10 cases, with a significantly higher recanalization rate than the EmboTrap III (100% vs. 50%, p = 0.03). For erythrocyte-rich clots, the recanalization rate was not significantly different in the PREMIER technique compared with the simple use of EmboTrap III (80% vs. 70%, p = 1.00).ConclusionThe PREMIER technique is a novel technique for acute large-vessel occlusions caused by fibrin-rich hard clots that hinders successful recanalization during mechanical thrombectomy.

Introduction: Hydrophilic polymer embolism in the brain is a delayed complication of cerebral angiography or endovascular therapy. Herein, we report a rare case of a hydrophilic polymer embolism in the brain due to endovascular catheter coil embolization of pulmonary venous shunts. Case report: A 16-year-old female presented with headache, dizziness, nausea, and dysesthesia in the left upper limb. Brain magnetic resonance imaging (MRI) revealed multiple bilateral subcortical white matter lesions with nodular gadolinium enhancement lesions surrounded with edema. Two weeks before onset, the patient underwent endovascular catheter coil embolization with two coils for two systemic-to-pulmonary venous shunts. We suspected that her multiple cerebral lesions were delayed allergic complications due to a catheter hydrophilic polymer-coating embolism after endovascular catheter coil embolization. Corticosteroid treatment rapidly improved neurological symptoms and MRI findings. Conclusion: To avoid unnecessary brain biopsy, careful history taking of previous catheterization is essential among patients presenting with focal deficits and punctate-enhancing brain lesions for the diagnosis of hydrophilic polymer embolism.

Objectives: The prolonged presence of infectious SARS-CoV-2 in deceased patients with COVID-19 has been reported. However, infectious virus titers have not been determined. Such information is important for public health, death investigation, and handling corpses. The aim of this study was to assess the level of SARS-CoV-2 infectivity in the corpses of patients with COVID-19. Methods: We collected 11 nasopharyngeal swabs and 19 lung tissue specimens from 11 autopsy cases with COVID-19 in 2021. We then investigated the viral genomic copy number by real-time reverse transcription-polymerase chain reaction and infectious titers by cell culture and virus isolation. Results: Infectious virus was present in six of 11 (55%) cases, four of 11 (36%) nasopharyngeal swabs, and nine of 19 (47%) lung specimens. The virus titers ranged from 6.00E + 01 plaque-forming units/ml to 2.09E + 06 plaque-forming units/g. In all cases in which an infectious virus was found, the time from death to discovery was within 1 day and the longest postmortem interval was 13 days. Conclusion: The corpses of patients with COVID-19 may have high titers of infectious virus after a long postmortem interval (up to 13 days). Therefore, appropriate infection control measures must be taken when handling corpses.

Spin dynamics induced by intense terahertz pulses are commonly observed by magnetooptical effects. Here, we show that magnetorefractive effect provides a second-harmonic magnon signal whose amplitude is comparably strong with the linear component, making it an efficient probe for detecting the inherent nonlinear spin dynamics in orthoferrites.

We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with NIR light. The determined magnetic field strength and field-enhancement spectrum are consistent with the theoretical predictions. This first report of the detection of a Tesla-class picosecond magnetic field pulse by MOS is expected to be useful in research on the control of magnetization in spintronic devices.

Abstract Gallium nitride (GaN) is one of the most technologically important semiconductors and a fundamental component in many optoelectronic and power devices. Low-resistivity GaN wafers are in demand and actively being developed to improve the performance of vertical GaN power devices necessary for high-voltage and high-frequency applications. For the development of GaN devices, nondestructive characterization of electrical properties particularly for carrier densities in the order of 1019 cm−3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 1020 cm−3 using THz time-domain ellipsometry in reflection configuration. The p- and s-polarized THz waves reflected off the GaN samples are measured and then corrected based on the analysis of multiple waveforms measured with a rotating analyzer. We show that performing such analysis leads to a ten times higher precision than by merely measuring the polarization components. As a result, the carrier density and mobility parameters can be unambiguously determined even at high conductivities.

Abstract Aims Hereditary transthyretin (ATTRv) amyloidosis is the most frequent and representative form of autosomal dominant hereditary systemic amyloidosis. Disease‐modifying treatments of the disease are more effective during the early stages, and we require biomarkers to detect early pathological changes for prompt diagnosis. This study aimed to investigate whether plasma growth differentiation factor 15 (GDF‐15) levels could aid detection of early pathological changes in ATTRv amyloidosis. Methods and results We retrospectively studied 32 patients with ATTRv amyloidosis, eight asymptomatic TTR mutation carriers, and eight healthy volunteers. We evaluated plasma GDF‐15 levels in these subjects as related to levels of brain natriuretic peptide and high‐sensitivity troponin T, echocardiographic features, 99mTc‐pyrophosphate (PYP) scans, and cardiac magnetic resonance imaging findings. Plasma GDF‐15 levels significantly increased even in asymptomatic TTR mutation carriers compared with healthy volunteers (P

Summary: Terahertz emission from ferromagnetic/non-magnetic spintronic heterostructures had been demonstrated as pump wavelength-independent. We report, however, the pump wavelength dependence of terahertz emission from an optimized Fe/Pt spintronic bilayer on MgO substrate. Maximum terahertz generation per total pump power was observed in the 1200- to 1800-nm pump wavelength range, and a marked decrease in the terahertz emission efficiency beyond 2500 nm (pump photon energies

This study aimed to evaluate the utility of immunohistochemical staining of vascular Notch3 deposits in biopsied unfixed frozen skin samples from patients with suspected cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We analyzed vascular Notch3 deposits in unfixed frozen skin biopsy samples obtained from 43 patients with suspected CADASIL by immunohistochemistry using antibodies against the extracellular domain (ECD) of Notch3. We also sequenced the NOTCH3 gene in all patients, as well as evaluated their symptoms and neuroimages. We found granular Notch3 ECD deposits in the vessel walls of unfixed frozen skin biopsy samples in 10 of the 43 suspected patients with CADASIL. All 10 cases with skin Notch3 ECD deposits also carried reported pathogenic variants in the NOTCH3 gene associated with CADASIL. NOTCH3 variants of unknown significance were found in the other four patients without vascular Notch3 ECD or granular osmiophilic material deposits in biopsied skin samples. The remaining 29 cases without vascular Notch3 ECD deposits did not have variants in the NOTCH3 gene. Immunohistochemical evaluation of vascular Notch3 ECD deposits in unfixed frozen biopsied skin samples may be useful for detecting Notch3 deposits in CADASIL.

This paper presents a metamaterial-based super-oscillatory lens (SOL) fabricated by photolithography on a glass substrate and designed to operate at sub-terahertz (sub-THz) frequencies. The lens consists of repeating crisscross patterns of five-ring slits with sub-wavelength diameter. The lens is capable of generating multiple focal points smaller than the diffraction limit, thereby allowing many points to be inspected simultaneously with sub-wavelength resolution. After elucidating the influence of the lens parameters on light collection through calculations by the finite element method, the fabricated lens was then evaluated through actual experiments and found to have a focal length of 7.5 mm (2.5λ) and a hot spot size of 2.01 mm (0.67λ) at 0.1 THz (λ = 3 mm), which is 0.27 times the diffraction limit of the lens. This demonstrated sub-diffraction focusing capability is highly effective for industrial inspection applications utilizing terahertz waves.

All mixed hybrid perovskite (MA(Sn, Pb)(Br,I)3) thin film was fabricated by sequential vacuum evaporation method. To optimize the first layer with PbBr2 and SnI2, we performed different annealing treatments. Further, MA(Sn, Pb)(Br, I)3 thin film was synthesized on the optimized first layer by evaporating MAI and post-annealing. The formed hybrid perovskite thin film exhibited absorptions at 1.0 and 1.7 THz with small absorbance (

The nondestructive mixing properties of optical resonance modes were investigated using a structure with a dielectric sandwiched between metallic sub-wavelength cut-through slit-array slabs. For the un-shifted slit-array configuration, the resonance mode repulsion around the intersection was more enhanced for an intermediate dielectric with a greater refractive index, though no anticrossing characteristic was seen for an air-gap structure. On the other hand, a lateral shift of the slit arrays enhanced the mode mixing effects even for an air-gap structure. The geometrically dependent characteristics are interpreted in terms of the difference between the (effective) refractive indices of both sides of the slits.

Objectives: To better determine the usefulness of mechanical thrombectomy for stroke patients with middle cerebral artery (MCA) branch occlusion, we investigated predictive factors related to poor outcome in acute, MCA branch occlusion stroke patients who had not undergone mechanical thrombectomy. Patients and methods: We retrospectively evaluated 204 consecutive acute stroke patients with MCA branch (M2-M4) occlusion. Two groups, based on activity of daily living scores at discharge, were compared: a dependent outcome group (mRS 3–6; n = 109) and an independent outcome group (mRS 0–2; n = 95), and the factors related to dependent outcomes at discharge determined. Results: The dependent group was older, had higher National Institutes of Health Stroke Scale (NIHSS) scores on admission, higher serum D-dimer and brain natriuretic peptide levels, and lower Alberta Stroke Program Early CT scores (ASPECTS) and rates of intravenous thrombolysis than the independent group. In multivariate analysis, age (OR 1.06; 95%CI 1.03–1.10), admission NIHSS score (OR 1.12; 95%CI 1.05–1.19), ASPECTS (OR 0.56; 95%CI 0.40–0.79), and intravenous thrombolysis (OR 0.22; 95%CI 0.08–0.57) were related to dependent outcomes. Decision curve analysis demonstrated that admission NIHSS scores were better predictors of dependency for threshold probabilities from 0.25 to 0.46. The optimal cutoff scores for predicting dependency were ≥8 (sensitivity 0.76, specificity 0.62) for the admission NIHSS score. Conclusions: Admission NIHSS scores might be useful predictors of dependent outcomes at discharge in acute ischemic stroke patients with MCA branch occlusion.

This paper describes the design and development of a cylindrical super-oscillatory lens (CSOL) for applications in the sub-terahertz frequency range, which are especially ideal for industrial inspection of films using terahertz (THz) and millimeter waves. Product inspections require high resolution (same as inspection with visible light), long working distance, and long depth of focus (DOF). However, these are difficult to achieve using conventional THz components due to diffraction limits. Here, we present a numerical approach in designing a 100 mm × 100 mm CSOL with optimum properties and performance for 0.1 THz (wavelength λ = 3 mm). Simulations show that, at a focal length of 70 mm (23.3λ), the focused beam by the optimized CSOL is a thin line with a width of 2.5 mm (0.84λ), which is 0.79 times the diffraction limit. The DOF of 10 mm (3.3λ) is longer than that of conventional lenses. The results also indicate that the generation of thin line-shaped focal beam is dominantly influenced by the outer part of the lens.

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra. The inflammatory activation of microglia participates in dopaminergic neurodegeneration in PD. Therefore, chemicals that inhibit microglial activation are considered to have therapeutic potential for PD. Aromatic (ar)-turmerone is a main component of turmeric oil extracted from Curcuma longa and has anti-inflammatory activity in cultured microglia. The aims of the present study are (1) to investigate whether naturally occurring S-enantiomer of ar-turmerone (S-Tur) protects dopaminergic neurons in midbrain slice cultures and (2) to examine ar-turmerone analogs that have higher activities than S-Tur in inhibiting microglial activation and protecting dopaminergic neurons. R-enantiomer (R-Tur) and two analogs showed slightly higher anti-inflammatory effects in microglial BV2 cells. S- and R-Tur and these two analogs reversed dopaminergic neurodegeneration triggered by microglial activation in midbrain slice cultures. Unexpectedly, this neuroprotection was independent of the inhibition of microglial activation. Additionally, two analogs more potently inhibited dopaminergic neurodegeneration triggered by a neurotoxin, 1-methyl-4-phenylpyridinium, than S-Tur. Taken together, we identified two ar-turmerone analogs that directly and potently protected dopaminergic neurons. An investigation using dopaminergic neuronal precursor cells suggested the possible involvement of nuclear factor erythroid 2-related factor 2 in this neuroprotection.

Wide-field quantum magnetometry using nitrogen-vacancy (NV) center in diamond can be a breakthrough for a nuclear magnetic resonance (NMR) in a small volume, which is important for biological applications. Although the coherence time of the electron spin of the NV center results in a limited frequency resolution for diamond magnetometry in the range 10–100 kHz, recent studies have shown that a phase-sensitive protocol can circumvent this limit using a confocal setup. We proposed a new measurement protocol, “iQdyne,” which facilitates an improved frequency resolution of wide-field imaging, unencumbered by the coherence limit imposed by the NV center. We demonstrated wide-field magnetometry with a frequency resolution of 238 mHz and a magnetic sensitivity of 65 nT/Hz1/2, which are superior to those obtained using a conventional XY8-based technique, and showed the potential of the iQdyne protocol for the wide-field NMR imaging.

We investigated the optical transmission properties of a metamaterial system in which a natural dielectric is inserted between metallic sub-wavelength slit arrays that behave as an artificial dielectric when the incident light wavelength is longer than the slit periodicity. Transmission spectra were measured using terahertz time-domain spectroscopy, and the experimental results were analyzed by simulations based on the finite-difference time-domain method. We revealed that the resonance characteristics are defined by the two diffraction-limit frequencies for the inner and outer openings of the slits, which are different for the insertion of the dielectric. We also determined further details on the blue-shift behavior specific to the even-order resonance modes by accounting for the refractive index of the inserted intermediate dielectric. In addition, we experimentally demonstrated that insertion of a dielectric having a high refraction index enhances the frequency repulsion at the anticrossing, i.e., the coupling strength, between the symmetric and antisymmetric optical modes. These experimental and theoretical results will be essential for understanding and developing applications for hybrid systems composed of dielectrics with both fixed and widely tunable refractive indices.

We investigate the optical transmittances of ion-irradiated sapphire crystals as potential vacuum ultraviolet (VUV) to near-infrared (NIR) window materials of fusion reactors. Under potential conditions in fusion reactors, sapphire crystals are irradiated with hydrogen (H), deuterium (D), and helium (He) ions with 1-keV energy and ∼ 1020-m-2 s-1 flux. Ion irradiation decreases the transmittances from 140 to 260 nm but hardly affects the transmittances from 300 to 1500 nm. H-ion and D-ion irradiation causes optical absorptions near 210 and 260 nm associated with an F-center and an F+-center, respectively. These F-type centers are classified as Schottky defects that can be removed through annealing above 1000 K. In contrast, He-ion irradiation does not cause optical absorptions above 200 nm because He-ions cannot be incorporated in the crystal lattice due to the large ionic radius of He-ions. Moreover, the significant decrease in transmittance of the ion-irradiated sapphire crystals from 140 to 180 nm is related to the light scattering on the crystal surface. Similar to diamond polishing, ion irradiation modifies the crystal surface thereby affecting the optical properties especially at shorter wavelengths. Although the transmittances in the VUV wavelengths decrease after ion irradiation, the transmittances can be improved through annealing above 1000 K. With an optical transmittance in the VUV region that can recover through simple annealing and with a high transparency from the ultraviolet (UV) to the NIR region, sapphire crystals can therefore be used as good optical windows inside modern fusion power reactors in terms of light particle loadings of hydrogen isotopes and helium.

Lithium diphenylbinaphtholate catalyzed the enantioselective Evans-Tishchenko reduction of achiral b-hydroxyketones to afford monoacyl-protected 1,3-diols with high stereoselectivities. In the reaction of racemic b-hydroxyketones, kinetic optical resolution occurred in a highly stereoselective manner.

We demonstrate a new method to detect terahertz (THz) power using a temperature-supersensitive capsulized cholesteric liquid crystal film based on the thermochromic and thermodiffusion effect, which is clearly observed. A quantitative visualization of the THz intensity up to 4.0 × 103 mW/cm2 is presented. The diameter of the color change area is linearly dependent on the THz radiation power above 0.07 mW in the steady state. Moreover, the THz power can be detected for 1 sec of radiation with a parabolic relation to the color change area. The THz power meter is robust, cost-effective, portable, and even flexible, and can be used in applications such as THz imaging, biological sensing, and inspection.