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Histopathological diagnoses are challenging for rare CD3-and CD20-negative extramedullary leukemias/lymphomas. We report 118 cases of CD3- CD20-extramedullary leukemias/lymphomas (2.4% of 4977 cases). CD45 was positive in 68% of cases. Forty-nine (41%) cases were anaplastic large cell lymphomas. Thirty-five (30%) cases were large B-cell lymphomas/plasmablastic lymphomas positive for at least one of the following markers: CD79a, PAX5, CD19, CD138, and MUM1. Nine (8%) cases were peripheral T/NK-cell lymphomas, where at least CD43, CD45RO, or cytotoxic molecules were positive; 4, 3, and 2 cases were extranodal NK/T-cell lymphoma, nasal type, peripheral T-cell lymphoma-not otherwise specified, and adult T-cell leukemia/lymphoma, respectively. The remaining 25 (21%) cases included 11, 8, and 6 cases of myeloid sarcoma, blastic plasmacytoid dendritic cell neoplasm, and B- or NK-cell lymphoblastic leukemia/lymphoma, respectively. For large B-cell lymphoma/plasmablastic lymphoma diagnosis, MUM1 (92%) was the most sensitive marker, followed by CD79a (63%), PAX5 (52%), CD138 (42%), and CD19 (36%). EBER 1 and HHV8 were positive in 32% and 0% of the cases. For peripheral T/NK-cell lymphomas other than ALCL, CD45RO and CD43 were positive in nine cases; however, cytotoxic molecules (TIA1, 86%; granzyme B, 71%) were the most sensitive markers. In conclusion, most cases of the 118 (2.4%) CD3

Objectives We aimed to investigate factors associated with impaired physical function [defined as Health Assessment Questionnaire Disability Index (HAQ-DI) >0.5] of old-old (aged 75–84 years) patients with rheumatoid arthritis. Methods Data from 15,185 rheumatoid arthritis patients in the National Database of Rheumatic Disease in Japan were extracted from 2017 to 2018. We enrolled 3708 patients aged 55–84 years in Simplified Disease Activity Index (SDAI) ≤11 and Steinbrocker Stage I/II. Factors associated with HAQ-DI >0.5 were analysed by multivariable logistic regression. Results About half of the old-old patients received methotrexate, which was lower than middle-aged (55–64 years) and young-old patients (65–74 years). The proportion of glucocorticoids in the old-old patients was highest among the three groups, and biological disease-modifying antirheumatic drugs were similarly used. The prevalence of HAQ-DI >0.5 was significantly higher in old-old patients with low disease activity than in those with remission. The same was true in the middle-aged and young-old patients. Multivariable analysis showed age, higher SDAI, glucocorticoid use, and methotrexate nonuse were significantly associated with HAQ-DI >0.5 in the old-old patients. Conclusions Achieving SDAI remission was an ideal goal for old-old patients in terms of physical function. Glucocorticoids and a low proportion of methotrexate use may influence the physical function of old-old patients.

We calculate the dynamics of fast neutrino flavor conversions with Boltzmann collisions of neutrino scatterings in a homogeneous system. We find the enhancement or suppression of the flavor conversions in various setups of the collision terms. We analyze the mechanism of fast flavor conversions based on the motion of polarization vectors in the cylindrical coordinate analogous to a pendulum motion. The phases of the all the polarization vectors synchronize in the linear evolution phase, and the phase deviation from the Hamiltonian governs the neutrino flavor conversions. In a non-linear regime of flavor conversions, the collision terms induce a spiral motion of the polarization vector and gradually make the phase space smaller. The collision terms align all of the polarization vectors, and the flavor conversions eventually settle into equilibrium when the distributions of neutrinos become isotropic. Though our current analysis does not fully clarify the non-linear phenomena of fast flavor conversions, the framework of the pendulum motion gives a new insight into this complicated phenomenon that will be helpful in further studies.

We investigate the neutrino flavor change effects due to neutrino self-interaction and shock wave propagation, as well as the matter effects on the neutrino process in core-collapsing supernovae (CCSNe). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamics model for SN1987A. For the presupernova model, we take an updated model, adjusted to explain SN1987A, which employs recent developments in the (n, γ) reaction rates for nuclei near the stability line (A ∼ 100). As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and nonequivalent luminosity models. The latter is taken from a synthetic analysis of CCSN simulation data, which quantitatively presented the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated using a shell model for light nuclei and a quasiparticle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei (7Li, 7Be, 11B, and 11C) and the heavy nuclei (92Nb, 98Tc, 138La, and 180Ta) produced by the neutrino process. The light nuclei abundances turn out to be sensitive to the Mikheyev–Smirnov–Wolfenstein (MSW) region around O-Ne-Mg layer while the heavy nuclei are mainly produced prior to the MSW region. Through detailed analyses, we find that neutrino self-interaction becomes a key ingredient, in addition to the MSW effect, for understanding the neutrino process and the relevant nuclear abundances. The normal mass hierarchy is shown to be more compatible with the meteorite data. The main nuclear reactions for each nucleus are also investigated in detail.

Deficiency for AIRE/Aire in both humans and mice results in the development of organ-specific autoimmune disease. We tested whether augmented and/or dysregulated AIRE/Aire expression might be also prone to the breakdown of self-tolerance. To define the effect of augmented Aire expression on the development of autoimmunity, antigen-specific clonal deletion and production of clonotypic regulatory T cells (Tregs) in the thymus were examined using mice expressing two additional copies of Aire in a heterozygous state (3xAire-knockin mice: 3xAire-KI). We found that both clonal deletion of autoreactive T cells and production of clonotypic Tregs in the thymus from 3xAire-KI were impaired in a T-cell receptor-transgenic system. Furthermore, 3xAire-KI females showed higher scores of experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein than wild-type littermates, suggesting that augmented Aire expression exacerbates organ-specific autoimmunity under disease-prone conditions. In humans, we found that one patient with amyopathic dermatomyositis showed CD3–CD19– cells expressing AIRE in the peripheral blood before the treatment but not during the remission phase treated with immunosuppressive drugs. Thus, not only loss of function of AIRE/Aire but also augmented and/or dysregulated expression of AIRE/Aire should be considered for the pathogenesis of organ-specific autoimmunity. We suggest that further analyses should be pursued to establish a novel link between organ-specific autoimmune disease and dysregulated AIRE expression in clinical settings.

Indium phosphide (InP) quantum dots (QDs) are attractive materials as cadmium- and lead-free emitters for wide-color gamut displays. However, the wider emission full-width at half-maximum (FWHM) of InP-QDs has been the obstacle to replacing cadmium selenide QDs. Here, we report that the presence of ZnCl2 during shell formation drastically improves the emission properties of InP-QDs. Scanning transmission electron microscope observation revealed that uniform and spherical particles were formed in the presence of ZnCl2. By combining the flow reaction of InP core QDs, kilogram-scale synthesis was achieved while maintaining excellent emission properties.

Background To investigate factors associated with normal physical function of middle-aged (55-64), old (65-74) or very old (75-84) patients with rheumatoid arthritis (RA). Methods Data from RA patients in the National Database of Rheumatic Diseases in Japan (NinJa) were extracted from April 2017 to March 2018. Factors associated with impaired physical function (Health Assessment Questionnaire Disability Index [HAQ-DI] >0.5) were analyzed by multivariable logistic regression. Association of glucocorticoids (GCs) and age with impaired physical function were presented as adjusted odds ratio (OR) for the 5 groups relative to middle-aged patients without GCs as the reference group. Results Low disease activity (3.3< simplified disease activity index [SDAI] ≤11) or remission (SDAI ≤3.3) was achieved in 3,466 (31.4%) or 3,021(27.4%) of 11,036 patients aged 55-84, respectively. To reduce the influence of joint destruction on HAQ-DI, we assessed the 3,708 patients in both SDAI ≤11 and Steinbrocker stage I/II. About half of the very old patients were receiving methotrexate, which was the lowest proportion amongst the three age groups. GCs were continued in 32.6% of very old patients, and the proportion was higher than in old and middle-aged patients. On the other hand, 16.2% of the very old patients received biological disease-modifying anti-rheumatic drugs (bDMARDs), and the proportions were similar among the three groups. SDAI was higher in patients with HAQ-DI >0.5 at all ages, and GCs was used more frequently in the old and very old patients with HAQ-DI >0.5, compared to those with HAQ-DI ≤0.5. To minimize the influence of disease activity on HAQ-DI, we selected the 2078 patients in both remission and stage I/II. Multivariable analysis revealed the use of GCs further increased the adjusted OR from 4.01 (95% confidence interval [CI] 2.30-6.99) to 6.81 (95%CI 3.65-12.7) in the very old patients, while the adjusted OR was 2.03 (95%CI 1.17-1.13) in the old patients without GCs, 2.22 (95%CI 1.13-4.36) in the old patients with GCs, and 0.73 (95%CI 0.21-2.56) in the middle-aged patients with GCs. Conclusions The negative impact of GCs was likely to most strongly influence physical function of very old patients than middle-aged or old patients.

We propose a linear imaging theory for differential phase contrast under the weak-phase-weak-amplitude object approximation. Contrast transfer functions are defined for thin and thick weak objects, and they successfully describe several imaging characteristics of differential phase contrast. We discuss the defocus dependence of the contrast for several examples: atomic resolution, a p-n junction, a heterointerface, and grain boundaries. Understanding the imaging characteristics helps in adjusting aberrations in DPC STEM.

We simulate neutrino-antineutrino oscillations caused by strong magnetic fields in dense matter. With the strong magnetic fields and large neutrino magnetic moments, Majorana neutrinos can reach flavor equilibrium. We find that the flavor equilibration of neutrino-antineutrino oscillations is sensitive to the values of the baryon density and the electron fraction inside the matter. The neutrino-antineutrino oscillations are suppressed in the case of the large baryon density in neutron (proton)-rich matter. On the other hand, the flavor equilibration occurs when the electron fraction is close to $0.5$ even in the large baryon density. From the simulations, we propose a necessary condition for the equilibration of neutrino-antineutrino oscillations in dense matter. We also study whether such necessary condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibration would be possible if the magnetic field on the surface of the proto-neutron star is larger than $10^{14}$ G which is the typical value of the magnetic fields of magnetars., 14 pages, 8 figures, accepted for publication in PRD

Infectious diseases, including those caused by fungi, remain important issues in patients receiving malignant lymphoma chemotherapy. We herein report a rare case of Exophiala dermatitidis fungemia during chemotherapy in a 67-year-old woman admitted to our hospital. She had a fever that could not be resolved despite antifungal therapy. Yeast-like fungi were detected in blood culture samples, but biochemical identification was difficult. E. dermatitidis, a black mold, was identified using time-of-flight mass spectrometry. The patient finally improved after her treatment was switched to voriconazole. Fungal infection is difficult to diagnose and treat, but this novel approach can improve patients' outcomes.

Lenalidomide is an effective therapeutic agent for multiple myeloma (MM). However, its efficacy in the context of chromosomal abnormalities (CA) is poorly understood. We retrospectively analyzed 83 patients with relapsed/refractory (RR) MM, who received lenalidomide plus low-dose dexamethasone (Ld), in the context of CA. The median age and number of prior therapies were 69 and 2, respectively. Three, 11, 45, and 19 patients achieved complete response, very good partial response, partial response, and stable disease, respectively. Median progression-free survival (PFS) and overall survival (OS) were 11.1 and 38.8 months, respectively. Seventy-two patients were evaluated for frequently observed translocations; median PFS was 24.4 months in 20 patients with t(11;14), 13.0 months in 16 patients with t(4;14), and 3.7 months in seven patients with t(14;16). G-banded karyotype analysis detected 11 hypodiploid patients, who had shorter PFS and OS (2.5 and 6.2 months, respectively) compared to others (13.0 and 43.7 months, respectively). Hypodiploid patients showed poor clinical outcome, whereas patients with t(11;14) showed favorable outcome. In summary, the present study presents the clinical impact of chromosomal abnormalities on the outcome of Ld therapy, and contributes to understanding the appropriate choice of lenalidomide-based therapy to achieve effective treatment of RR MM.

A 42-year-old female complaining of fever and night sweats was diagnosed with acute megakaryoblastic blast phase chronic myeloid leukemia (CML-BP). She had massive splenomegaly, left pleural effusion with leukemia infiltration, and moderate myelofibrosis. She received dasatinib monotherapy (140 mg/day) as for induction, after which her pleural effusion rapidly resolved and hematological remission was achieved. However, CML relapsed 4 months after starting dasatinib due to increased BCR-ABL fusion signals in the peripheral blood. The T315I mutation was also detected at the recurrence of CML. As a salvage treatment, ponatinib monotherapy (45 mg/day) was started immediately. After 5 months, BCR-ABL fusion signals decreased to 5%, and myelofibrosis improved from MF Grade 2 to 1; she then underwent allogeneic bone marrow transplantation from an unrelated donor. However, the graft failed, and cord blood transplantation (CBT) was performed. Ponatinib (15 mg/day) was continued after CBT as a maintenance treatment, with molecular complete response continuing for more than 1 year with no severe adverse events, including cardiovascular events. There is limited evidence regarding the optimal dose and schedule of ponatinib before and after allogeneic hematopoietic stem cell transplantation, especially in patients with CML-BP having T315I mutation; thus, well-designed clinical trials are warranted.

We calculate the abundances of 7Li, 11B, 92Nb, 98Tc, 138La, and 180Ta produced by neutrino (ν)-induced reactions in a core-collapse supernova explosion. We consider the modification by ν self-interaction (ν-SI) near the neutrinosphere and the Mikheyev–Smirnov–Wolfenstein (MSW) effect in the outer layers based on time-dependent neutrino energy spectra. Abundances of 7Li and the heavy isotopes 92Nb, 98Tc, and 138La are reduced by a factor of 1.5–2.0 by the ν-SI. In contrast, 11B is relatively insensitive to the ν-SI. We find that the abundance ratio of heavy to light nuclei, 138La/11B, is sensitive to the neutrino mass hierarchy, and the normal mass hierarchy is more likely to be consistent with the solar meteoritic abundances.

We calculate Galactic Chemical Evolution (GCE) of Mo and Ru by taking into account the contribution from $\nu p$-process nucleosynthesis. We estimate yields of $p$-nuclei such as $^{92,94}\mathrm{Mo}$ and $^{96,98}\mathrm{Ru}$ through the $\nu p$-process in various supernova (SN) progenitors based upon recent models. In particular, the $\nu p$-process in energetic hypernovae produces a large amount of $p$-nuclei compared to the yield in ordinary core-collapse SNe. Because of this the abundances of $^{92,94}\mathrm{Mo}$ and $^{96,98}\mathrm{Ru}$ in the Galaxy are significantly enhanced at [Fe/H]=0 by the $\nu p$-process. We find that the $\nu p$-process in hypernovae is the main contributor to the elemental abundance of $^{92}$Mo at low metallicity [Fe/H$], Comment: 15 pages, 5 figures, accepted for publication in ApJ

Idiopathic inflammatory myopathies (IIMs) are heterogeneous disorders that affect the skeletal muscles. Polymyositis, dermatomyositis, and inclusion body myositis are major IIM subsets. Immune-mediated necrotizing myopathy became recognized as a potentially new IIM subset. Since the new classification criteria published by the International Myositis Classification Criteria Project have higher sensitivity and specificity for IIM classification and subclassification than the previous criteria, they should help precise diagnosis. It should be noted that several tests available in current clinical practice, such as electromyography, magnetic resonance imaging, and other myositis-specific autoantibodies than anti-Jo-1 antibodies, were not included in the new criteria. As for treatment, glucocorticoids are used empirically as the first-line treatment despite their various adverse effects. Concomitant treatment with steroid-sparing immunosuppressive agents, including methotrexate, azathioprine, calcineurin inhibitors, mycophenolate mofetil, and cyclophosphamide, reduces successfully initial glucocorticoid doses for the remission induction, the relapse risk during glucocorticoid tapering, and adverse effects of glucocorticoids. Treatment with biologics, including rituximab and abatacept, seems promising in some IIM patients. Multi-target treatment with glucocorticoids and several steroid-sparing immunosuppressive agents is effective in refractory IIM patients. Considering proven steroid-sparing efficacy and tolerability of multi-target treatment in patients with other autoimmune diseases, it should be a good therapeutic option for IIMs.

In this work, green-emitting InP/ZnS quantum dots (QDs) modified with 1-dodecanethiol were embedded into silica by two methods to improve their photostability while maintaining a high photoluminescence quantum yield (PLQY) and a color coordinate. A monolithic QD-silica composite prepared by a non-aqueous route with tetraethyl orthosilicate and lactic acid featured low transparency, a loss of the color purity of green, and a PLQY of 1.6%, which was considerably lower than that of the original QDs (67%). The decrease of the PLQY was attributed to QD aggregation in the sol–gel process and degradation of the QDs by the acid. The alternative method involved stirring a toluene dispersion of the QDs with tetramethyl orthosilicate (TMOS) for 20 h or 7 days. The PLQY of the TMOS-modified InP/ZnS QDs (20 h) was 62%, which was only slightly lower than that of the original QDs. The PLQY decreased to 52% when the duration of aging was prolonged to 7 days. This decrease was attributed to desorption of surface modifiers from the QD surface and oxidative degradation by oxygen dissolved in toluene. Herein, the color coordinate was maintained stably. Photostability was evaluated by continuous irradiation of the samples by a blue light emitting diode. The decrease of photoluminescence (PL) intensity was suppressed by the silica encapsulation. In particular, the PL intensity of the TMOS-modified InP/ZnS QD sample (7 d) maintained 99% of its initial intensity. Silica encapsulation of InP/ZnS QDs prevented contact of the QDs with oxygen in the air, resulting in improved photostability.

We have developed a method to precisely measure spatial coherence in electron beams. The method does not require an electron biprism and can be implemented in existing analytical transmission electron microscopes equipped with a post-column energy filter. By fitting the Airy diffraction pattern of the selector aperture, various parameters such as geometric aberrations of the lens system and the point-spread function of the diffraction blurring are precisely determined. From the measurements of various beam diameters, components that are attributed to the partial spatial coherence are successfully separated from the point-spread functions. A linear relationship between the spatial coherence length and beam diameter is revealed, thus indicating that a wide range of coherence lengths can be determined by our proposed method as long as the coherence length remains >80% of the aperture diameter. A remarkable feature of this method is its ability to simultaneously determine diffraction blurring and lens aberrations. Possible applications of this method are also discussed.

Electric field mapping using segmented detectors in the scanning transmission electron microscope has recently been achieved at the nanometre scale. However, converting these results to quantitative field measurements involves assumptions whose validity is unclear for thick specimens. We consider three approaches to quantitative reconstruction of the projected electric potential using segmented detectors: a segmented detector approximation to differential phase contrast and two variants on ptychographical reconstruction. Limitations to these approaches are also studied, particularly errors arising from detector segment size, inelastic scattering, and non-periodic boundary conditions. A simple calibration experiment is described which corrects the differential phase contrast reconstruction to give reliable quantitative results despite the finite detector segment size and the effects of plasmon scattering in thick specimens. A plasmon scattering correction to the segmented detector ptychography approaches is also given. Avoiding the imposition of periodic boundary conditions on the reconstructed projected electric potential leads to more realistic reconstructions.

The degradation of CuInS2 (CIS) quantum dots (QDs) under excitation light due to photo-oxidization by O2 has been a significant problem. Embedding QDs into a matrix to protect them against O2 would improve their photostability. In this paper, hydrophilized CIS/ZnS/ZnS QDs prepared by a ligand exchange method were embedded in silica through a sol–gel method using tetramethylammonium silicate (TMAS) aqueous solution, in which negatively-charged nanoparticles can be well dispersed. QDs modified with 3-mercaptopropionic acid (MPA) were well dispersed into TMAS-derived silica. The obtained monolithic TMAS-derived silica composites containing embedded MPA-modified CIS/ZnS/ZnS QDs exhibited high photoluminescence (PL) quantum yields (43–47%). Changes in PL intensity under continuous excitation were measured to evaluate the photostability of the QDs. The PL intensity of the composite was 105% that of the initial value after 5 h irradiation, while the PL intensities of as-prepared QDs and a PMMA composite decreased to 88% and 92%, respectively. The good gas barrier properties of TMAS-derived silica likely caused the high photostability by preventing O2 from reaching the surface of the embedded QDs.

The Richter syndrome (RS) is defined as a histologically diagnosed diffuse large B-cell lymphoma (DLBCL) or Hodgkin lymphoma (HL) in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma. A standard treatment for RS has not yet been established. Most patients with RS are treated with combination chemotherapy regimens used for de novo DLBCL or HL. Recently, the Bruton's tyrosine kinase inhibitor, ibrutinib (IBR), has shown remarkable efficacy in CLL; however, limited evidence exists regarding its single agent efficacy in RS. We encountered two patients with RS in whom CLL transformed to DLBCL, confirmed by G-banding/spectral karyotyping analysis. Both patients achieved durable responses for 12 and 10 months, with IBR alone. Hemorrhagic cystitis due to adenovirus occurred in one patient at an initial dose of 420 mg/day, but a dose reduction to 280 mg/day made long-term continuation of IBR possible. Interestingly, retreatment with IBR alone achieved disease control again for 5.5 and 2 months, after these patients underwent salvage chemotherapies for aggressive relapse.

The nanoscale electric potential distribution in a gallium arsenide single p–n junction cell under artificial illumination, or the photovoltaic (PV) effect, was investigated using in situ electron holography with a transmission electron microscope. A custom-made specimen holder with biasing and illumination capabilities was used for this purpose. To determine the practical potential of the specimen prepared by a focused ion beam (FIB), the thickness of active layers that directly contribute to the PV effect was accurately derived by analyzing the results of in situ biasing electron holography. In situ light-illumination electron holography directly visualized the PV effect in the cell, where the potential difference between the p and n regions decreased with the increase in the intensity of light illumination. Using PV simulations, in conjunction with some reasonable assumptions regarding the practical specimen parameters in the FIB-milled specimen, we can generate a credible explanation of the experimental result. These findings will help to fully understand the PV effect in various types of solar cells, including perovskite and quantum dot cells.

It is well known that dynamical diffraction varies with changes in sample thickness and local crystal orientation (due to sample bending). In differential phase contrast scanning transmission electron microscopy (DPC-STEM), this can produce contrast comparable to that arising from the long-range electromagnetic fields probed by this technique. Through simulation we explore the scale of these dynamical diffraction artefacts and introduce a metric for the magnitude of their contribution to the contrast. We show that precession over an angular range of a few milliradian can suppress this contribution to the contrast by one-to-two orders of magnitude. Our exploration centres around a case study of GaAs near the [011] zone-axis orientation using a probe-forming aperture semiangle on the order of 0.1 mrad at 300 keV, but the trends found and methodology used are expected to apply more generally.

The n-/p-type stability of a silicon clathrate in which silicon was substituted with nickel or platinum was evaluated by density functional theory calculations. Then, Ba8Pt5Si41 and Ba8Pt1.5Ni3.5Si41 were synthesized, and their thermoelectric properties were investigated. The polycrystalline compounds, which have a type-I clathrate structure, were prepared through arc melting and spark-plasma-sintering. The crystal structures and elemental compositions of the synthesized samples were characterized via powder x-ray diffraction and electron microprobe analyses, respectively. The temperature dependence of both the electrical resistivity and the Seebeck coefficient was measured.

Local electromagnetic fields in a specimen is measured at high spatial resolutions using differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). According to previous studies, DPC signals can be quantified by measuring the center of mass of the diffraction pattern intensity and/or performing a deconvolution method based on a phase contrast transfer function (PCTF). However, when using a segmented detector, the field strength has been considerably underestimated for a very thick specimen. The main cause of the underestimation is assumed to be inelastic scattering, mainly bulk plasmon scattering. In this study, we develop a method to remove this inelastic scattering effect from segmented detector DPC signals by modifying the PCTF deconvolution method. Field quantification results using this new technique are compared with those using pixelated detector DPC and electron holography, and all results indicated good agreement within an error margin.

Background Pneumothorax is a rare but life-threatening complication associated with pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Case presentation Informed consent was obtained from the patient himself.A 50-year-old man presented with a 9-day history of fever, cough, and dyspnoea. He was diagnosed with coronavirus disease 2019 (COVID-19) pneumonia and was admitted to the Medical Hospital, Tokyo Medical and Dental University. Chest CT showed diffuse patchy ground-glass opacities (GGOs). His state of oxygenation deteriorated, and mechanical ventilation was initiated on day 4 after admission (12th day from onset). He improved gradually and was weaned from ventilation on day 15. Sudden onset of bilateral pneumothorax occurred on day 21 with severe respiratory failure, and chest CT revealed pneumatocele formation on both lower lobes. Conclusions Pneumothorax is a notable complication in cases of severe COVID-19 pneumonia, especially in those who require positive-pressure ventilation.

The innate electric potentials in biased p- and n-type GaAs compound semiconductors and the built-in potential were successfully measured with high accuracy and precision by applying in situ phase-shifting electron holography to a wedge-shaped GaAs specimen. A cryo-focused-ion-beam system was used to prepare the 35°-wedge-shaped specimen with smooth surfaces for a precise measurement. The specimen was biased in a transmission electron microscope, and holograms with high-contrast interference fringes were recorded for the phase-shifting method. A clear phase image around the p-n junction was reconstructed even in a thick region (thickness of ~700 nm) at a spatial resolution of 1 nm and precision of 0.01 rad. The innate electric potentials of the unbiased p- and n-type layers were measured to be 12.96 ± 0.17 V and 14.43 ± 0.19 V, respectively. The built-in potential was determined to be 1.48 ± 0.02 V. In addition, the in situ biasing measurement revealed that the measured electric-potential difference between the p and n regions changed by an amount equal to the voltage applied to the specimen, which indicates that all of the external voltage was applied to the p-n junction and that no voltage loss occurred at the other regions.