Tohoku University Research Articles

Experimental study of cavitating flow influenced by heat transfer from heated hydrofoil

This study experimentally investigated the influence of heat transfer from a heated hydrofoil on cavitating flow to understand the evaporation phenomenon under high-heat-flux and high-speed conditions. A temperature difference was generated between the hydrofoil and mainstream by installing an aluminum nitride heater in a NACA0015 hydrofoil fabricated from copper. A cavitation experiment was performed in a high-temperature water cavitation tunnel at the Institute of Fluid Science, Tohoku University. The effect of heating on cavitating flow was evaluated by changing the mainstream velocity and pressure, namely the cavitation number, at a fixed heater power of 860 W. Results showed that the heat transfer from the hydrofoil affected cavitating flow in terms of the cavity length, cavity aspect, and periodicity. The effect on the cavity length became stronger at a lower velocity owing to a higher hydrofoil temperature. The variation in periodicity implied that the heating effect reduced the unsteadiness of cavitation. A modified cavitation number was proposed by considering the heat transfer from the heated wall. A thermal correction term was derived by considering that the fluid temperature close to the heated hydrofoil was affected by the turbulent convective heat transfer between the mainstream and hydrofoil. The corrected cavitation number can be considered as a parameter that describes the cavity length in the isothermal and heated cases in a unified expression.

Temporal and Directional Cue Effects on the Cocktail Party Problem for Patients With Listening Difficulties Without Clinical Hearing Loss.

To evaluate the listening difficulty in a cocktail party environment in the sound field in order to better demonstrate patients' difficulties listening in noise, and to examine temporal and directional cue effects on the speech intelligibility in patients with listening difficulties in noise in comparison with control subjects. This study examined and analyzed 16 control subjects without any complaints of listening difficulties and 16 patients who had visited the outpatient clinic of the Department of Otolaryngology-Head and Neck Surgery, Tohoku University Hospital, with complaints of listening difficulties, especially in background crowded conditions, despite having relatively good hearing on routine audiograms and speech audiometry. Using five loudspeakers located in front of the subject and at 30° and 60° to the left and right from the front, word intelligibility for the target voice (female talker) presented from one of the loudspeakers in random order with four distractor voices (male talker) was assessed under the following cue conditions: (1) "no additional temporal/directional cue (only talker sex as a cue)"; (2) "fixed temporal cue without directional cue" (white noise bursts [cue sounds] were presented from the five loudspeakers just before word presentation at 500-ms intervals); (3) "directional + variable temporal cues" [cue sounds were presented from the loudspeaker where the next target word would be presented with a variable inter-stimulus interval [ISI] of 500, 1000, 1500, or 2000 ms between the cue sound and word presentation); and (4) "directional + fixed temporal cues" (cue sounds were presented from the loudspeaker where the next target word would be presented with a fixed ISI of 500 ms). The results indicated the following: (1) word intelligibility under distractors was significantly deteriorated in patients with listening difficulties compared with control subjects, although the clinical speech in noise test using the headphone system did not show any significant differences between the two groups; (2) word intelligibility under distractors for patients with listening difficulties was significantly improved with directional cues presented in advance; and (3) under most cue conditions, individual differences in word intelligibility among patients with listening difficulties were significantly correlated with their dichotic listening ability, which is one of the indicators used to assess auditory selective attention ability. The results of this study indicate the usefulness of the presentation of directional cues for speech comprehension in the cocktail party situation in patients with listening difficulties, as well as the importance of evaluating the degree of listening difficulties spatially in the cocktail party situation.

Current Trends and Research Hotspots in Pancreatic Stellate Cells: A Bibliometric Study.

BackgroundPancreatic stellate cells (PSCs) play crucial roles in acute/chronic pancreatitis and pancreatic cancer. In this study, bibliometric analysis was used to quantitatively and qualitatively analyze the literature related to PSCs from 1998-2021 to summarize the current trends and research topics in this field.MethodsRelevant literature data were downloaded from the Science Citation Index Expanded Web of Science Core Collection (WoSCC) on April 07, 2021, using Clarivate Analytics. Biblioshiny R packages, VOSviewer, Citespace, BICOMB, gCLUTO, and the Online Analysis Platform of Literature Metrology (http://bibliometric.com) were used to analyze the manually selected data.ResultsA total of 958 relevant studies published in 48 countries or regions were identified. The United States of America (USA) had the highest number of publications, followed by the People’s Republic of China, Germany, and Japan. Tohoku University (Japan), the University of New South Wales (Australia), the University of Texas MD Anderson Cancer Center (USA), Technical University of Munich (Germany), and University of Rostock (Germany) were the top five institutions with most publications. Nine major clusters were generated using reference co-citation analysis. Keyword burst detection revealed that progression (2016-2021), microenvironment (2016-2021), and tumor microenvironment (2017-2021) were the current frontier keywords. Biclustering analysis identified five research hotspots in the field of PSCs during 1998-2021.ConclusionIn this study, a scientometric analysis of 958 original documents related to PSCs showed that the research topics of these studies are likely in the transition from acute/chronic pancreatitis to pancreatic cancer. The current research trends regarding PSCs are related to pancreatic cancer, such as tumor microenvironment. This study summarizes five research hotspots in the field of PSCs between 1998 and 2021 and thus may provide insights for future research.

1453-P: Possible Delta- to Beta-Cell Transdifferentiation in Aged Diabetic Mutant CRY1 Transgenic Mice

Cysteine414 (zinc-binding site of mCRY1) -alanine mutant mCRY1 transgenic mice (TG) show diabetes characterized by the reduction of β-cell proliferation due to the characters of senescence-associated secretory phenotype (SASP) in β-cells as we have reported at ADA Scientific Sessions in 2015. We also showed that various structural remodeling progresses in the islets of TG age-dependently: the increase of the population ratios of α-cell to β-cell and of ∂-cell to β-cell as well as fibrillation, angiogenesis and also the generation of mucin-producing atypical intra-islet ducts. Also, we revealed that trefoil factor family 2 (TFF2) is up-regulated in the β-cell of aged TG (Okano S. et al., ADA Scientific Sessions in 2020). To explore the mechanisms of keeping of the amount of β-cells under hyperglycemia for prolonged period in TG, we further conducted detailed double immune-staining experiments in the pancreatic sections of various ages (approximately 1, 10, and 19 months) of TG. The results demonstrated that, somatostatin and insulin double-positive cells were observed exclusively in aged TG (19 months of age). In wild-type mice (WT) of all stages, the double-positive cells were not observed. No glucagon and insulin double-positive cell was observed in islets of both TG and WT of all stages. In addition, scrutinized analyses demonstrated that not only β-cells but also small portion of somatostatin-positive cells express TFF2 in islets of aged TG. Taken together, these results suggest the possible ∂-cell to β-cell transdifferentiation in aged TG, that is, ∂-cells may play some role as the source for β-cells to supply new β-cells for islets in TG. Disclosure S.Okano: None. A.Yasui: None. K.Satoh: None. S.Kanno: None. M.Igarashi: None. O.Nakajima: None. Funding Grants-in-Aid for Scientific Research (19K07498). The Joint Research Program of IDAC, Tohoku University (38).

Efficacy and safety of mRNA SARS-CoV-2 vaccines in lung transplant recipients

BackgroundTo date, reports addressing the antibody response following mRNA SARS-CoV-2 vaccination in lung transplant (LTX) recipients are limited. Thus, the aim of this clinical study was to investigate the efficacy and safety of the vaccines in LTX recipients compared to controls. MethodsAn open-label, nonrandomized prospective study was conducted at Tohoku University Hospital. LTX recipients and controls who received either the BNT162b2 vaccine or the mRNA-1273 vaccine were recruited, and SARS-CoV-2 IgG was measured before and after vaccination. The adverse events were reviewed. Predictors of negative serology after vaccination were evaluated with logistic regression. ResultsForty-one LTX recipients and 24 controls were analyzed. Although all controls had a positive antibody response to a SARS-CoV-2 mRNA vaccine, antibody response was found in 24.4% of LTX recipients (p < .0001). The amount of SARS-CoV-2 IgG following the 2nd dose significantly climbed to 6557 AU/mL in controls, whereas the increase in IgG in LTX recipients was 8.3 AU/mL (p < .0001). Fewer LTX recipients developed systemic fever than controls (p < .0001) despite equivalent overall adverse event percentages in both groups. A higher plasma concentration of mycophenolate was a significant predictor of negative serology (p = .032). ConclusionsAn impaired antibody response to mRNA vaccines was significantly found in LTX recipients compared to controls and was associated with the plasma concentration of mycophenolate. While repeating mRNA vaccination may be one of the strategies to improve antibody response given the safety of the vaccines, emerging data on humoral immune responses based on immunosuppression regimens in LTX recipients should be studied (jRCT1021210009).

Neutron irradiation effect on critical current and critical temperature of Nb3Sn wire

The ITER project is ongoing in France, and it is expected that a lot of high energy neutrons will be generated, and some neutrons will reach to superconducting magnets. To keep the safe and stable operation of the superconducting magnets, the neutron irradiation data must be piled up and the mechanisms of the irradiation effect must be investigated. A 15.5 T superconducting magnet and a variable temperature insert were installed in a radiation control area at Oarai centre in Tohoku University, and the superconducting properties of the irradiated Nb3Sn wires have been evaluated. The critical current was improved once and drastically dropped after irradiation of 1023 n/m2, and the critical temperature degraded monotonically, and the critical magnetic field decreased around 17 T after the irradiation of 1023 n/m2. The mechanism of the irradiation effect was discussed based on a flux pinning concept.

Investigation of the diversity of human papillomavirus 16 variants and L1 antigenic regions relevant for the prevention of human papillomavirus-related oropharyngeal cancer in Japan

ObjectiveThis study aimed to investigate the distribution of human papillomavirus 16 (HPV16) variants that contribute to the development of HPV-related oropharyngeal carcinoma (HPV-OPC) in the Japanese population and to evaluate genetic variations in the sequence encoding the L1 antigen region of the viral outer shell that is targeted by existing vaccines and is relevant for designing a prevention strategy to combat the exponential increase in HPV-OPC cases in Japan. MethodsSeventy Japanese HPV-OPC patients treated at Tohoku University Hospital were included in the study. DNA was extracted from formalin-fixed, paraffin-embedded tissue samples. Polymerase chain reaction and direct nucleotide sequencing were performed to determine the nucleotide polymorphisms necessary for the classification of HPV16 variants and to assess genetic diversity in the HPV16 L1 antigen region, including the BC, DE, EF, FG, and HI loops. ResultsThe most common variant of HPV16 was the A4 sublineage (88.6%), conventionally called the Asian type, followed by the A1/2/3 (10.0%) sublineage, classified as the European type. The only nonsynonymous substitution detected in the L1 antigen loop region was p.N181T in the EF loop, which was found in 28/70 (40%) cases. In contrast, no nonsynonymous substitutions were observed in the DE, FG, and HI loops, which are particularly important regions in the antigen loop targeted by existing HPV vaccines. ConclusionThe most common HPV16 variant in Japanese HPV-OPC patients was the A4 subtype. The L1 antigen region is highly conserved, suggesting sufficient efficacy of existing HPV vaccines. These findings provide important information that will aid in the design of an HPV16 infection control strategy using existing HPV vaccines to prevent the spread of HPV-OPC in Japan.

First person – Momoe Nakajo

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Momoe Nakajo is first author on ‘ Centrosome maturation requires phosphorylation-mediated sequential domain interactions of SPD-5’, published in JCS. Momoe is a PhD student in the lab of Asako Sugimoto at the Laboratory of Developmental Dynamics, Tohoku University, Sendai, Japan, investigating the mechanisms involved in formation of microtubule-organizing centers.

An accelerator experiment for junior and senior high school students to improve students’ involvement in fundamental physics

In Japan, research activities by junior and senior high school students show an upward trend. However, there are limited examples of research activities in the field of elementary particles and atoms. This is due to the difficulty associated with procuring research tools such as accelerators or particle detectors. Therefore, we hosted the ‘Accel Kitchen’ in 2018 and 2019 at the Cyclotron and Radioisotope Center (CYRIC) in Tohoku University where junior and senior high school students could participate in ongoing research of particle and atomic physics. At each workshop, 12 junior and senior high school students participated in the beam experiment, including the production of francium atoms (Fr) by the fusion reaction of oxygen and gold, optimizing the transport of the ion beam and identifying the alpha decay nuclei, and laser trapping of Fr for two days. Each group that was involved in the experiment was supported by researchers and university students who acted as mentors. This was the first opportunity for junior and senior high school students to know about the particle beam experiment in Japan.

Wind Tunnel Installation Effects on Japan Aerospace Exploration Agency’s Standard Model

This paper investigates the interference effects of wind tunnel floor and walls on the Japan Aerospace Exploration Agency’s High-Lift Configuration Standard Model (JSM) as an extension to a paper published in the Journal of Aircraft, Vol. 56, No. 3, May–June 2019, pp. 1080–1098. An unstructured hybrid grid generator, MEGG3D, was applied to JSM wing–body and wing–body–nacelle–pylon configurations to generate grids for free-air flow conditions. These grids were then reused in an investigation of the interference effects of Japan Aerospace Exploration Agency’s low-speed wind tunnel walls to better compare the computational results, both with each other and with experiment. The geometry of the wind tunnel used in our computational simulations is described in detail so that they can be reproduced. A Reynolds-averaged Navier–Stokes flow solver for unstructured hybrid grids, the Tohoku University Aerodynamic Simulation (TAS) code, was used for the simulations. The computational results indicated that the standoff and test section floor boundary layer significantly affected the aerodynamics of the JSM at high angles of attack. Better agreement with experiment was observed for the wing–body configuration in the aerodynamic characteristics near maximum lift if the effects of the standoff and floor boundary layer were considered.

Elucidating 2D Charge-Density-Wave Atomic Structure in an MX-Chain by the 3D-ΔPair Distribution Function Method.

The front cover artwork is provided by Prof. Masahiro Yamashita's group at Tohoku University and designed by Dr. Laurent Guérin at University of Rennes 1. The image illustrates that the atomic structure of a 2D charge density wave can be revealed although the planes associated to this local 2D order are randomly stacked preventing the use of conventional structure determination techniques. Read the full text of the Research Article at 10.1002/cphc.202100857.

Research advances in the diagnosis and treatment of moyamoya disease: a bibliometric analysis

Moyamoya disease is a rare cerebrovascular condition involving stenotic carotid arteries and the formation of abnormal blood vessels. In this study, we aimed to characterize the key players involved in moyamoya research at the individual and institutional level and to identify the critical publications that have advanced our understanding of this disease. We performed a title-specific search of the Web of Science database using the search term "moyamoya" for publications dating from 1900 to April 2020. The 100 most frequently cited articles were obtained, screened for duplicates, and reviewed by 2 independent reviewers. These 100 articles were cited an average of 150 times each (range, 74 to 1,360 citations per article). Publication dates ranged from 1969 to 2016, with the largest number of publications (n=40) cited between 2000 and 2009. The article with the greatest number of citations (1,360 citations) was "Cerebrovascular 'moyamoya' disease: disease showing abnormal net-like vessels in base of brain," by Suzuki and Takaku, published in the Archives of Neurology, 1969. Stroke published the greatest number of the most frequently cited articles (23 of 100). The institution that contributed the most articles was Tohoku University (16%); the majority of the most frequently cited articles originated in Japan (62%). We identified the 100 most cited articles on moyamoya disease over the past 51 years to recognize significant and impactful works. These results can be used as a guide to evaluate our current understanding of moyamoya disease and to direct future efforts.

Rapid and quantitative uncertainty estimation of coseismic slip distribution for large interplate earthquakes using real-time GNSS data and its application to tsunami inundation prediction

This study proposes a new method for the uncertainty estimation of coseismic slip distribution on the plate interface deduced from real-time global navigation satellite system (GNSS) data and explores its application for tsunami inundation prediction. Jointly developed by the Geospatial Information Authority of Japan and Tohoku University, REGARD (REal-time GEONET Analysis system for Rapid Deformation monitoring) estimates coseismic fault models (a single rectangular fault model and slip distribution model) in real time to support tsunami prediction. The estimated results are adopted as part of the Disaster Information System, which is used by the Cabinet Office of the Government of Japan to assess tsunami inundation and damage. However, the REGARD system currently struggles to estimate the quantitative uncertainty of the estimated result, although the obtained result should contain both observation and modeling errors caused by the model settings. Understanding such quantitative uncertainties based on the input data is essential for utilizing this resource for disaster response. We developed an algorithm that estimates the coseismic slip distribution and its uncertainties using Markov chain Monte Carlo methods. We focused on the Nankai Trough of southwest Japan, where megathrust earthquakes have repeatedly occurred, and used simulation data to assume a Hoei-type earthquake. We divided the 2951 rectangular subfaults on the plate interface and designed a multistage sampling flow with stepwise perturbation groups. As a result, we successfully estimated the slip distribution and its uncertainty at the 95% confidence interval of the posterior probability density function. Furthermore, we developed a new visualization procedure that shows the risk of tsunami inundation and the probability on a map. Under the algorithm, we regarded the Markov chain Monte Carlo samples as individual fault models and clustered them using the k-means approach to obtain different tsunami source scenarios. We then calculated the parallel tsunami inundations and integrated the results on the map. This map, which expresses the uncertainties of tsunami inundation caused by uncertainties in the coseismic fault estimation, offers quantitative and real time insights into possible worst-case scenarios.Graphical

Advances in understanding of the natural history, mechanism, extra‐muscular manifestations and treatment of GNE myopathy

AbstractGNE myopathy is an autosomal recessive adult‐onset distal myopathy caused by biallelic variants in the GNE gene, which encodes a protein with two key enzymatic activities in the biosynthesis of sialic acid. In 1981, there was a report of a Japanese family in which muscle biopsies showed rimmed vacuoles in tibialis anterior with relative sparing of the quadriceps muscles. Twenty years later, the causative gene was identified to be GNE. Our group has constructed a mouse model that recapitulates the symptoms of GNE myopathy in patients and demonstrates the therapeutic effects of oral sialic acid supplementation on muscle phenotypes. The first clinical trial of N‐acetylneuraminic acid (NeuAc) was conducted in 2010 at Tohoku University, and several clinical trials are now underway at multiple sites. Patient registries have also been started, including the Japanese Registry of Muscular Dystrophy (Remudy, established in 2012) and the online international GNE Myopathy Disease Monitoring Program (launched in 2014). These registries have allowed collection of comprehensive patient data, including new clinical features suggesting that GNE myopathy is not only a disease of skeletal muscle. In this review, we summarize the history of research on GNE myopathy and discuss the mechanism of the disease and its more recently identified features.

Simultaneous Local Capacitance-Voltage Profiling and Deep Level Transient Spectroscopy Using Time-Resolved Scanning Nonlinear Dielectric Microscopy

Abstract Scanning nonlinear dielectric microscopy (SNDM) is a scanning probe technique that measures changes in oscillation frequency between the probe tip and a voltage-biased sample. As the probe moves across the surface of a semiconductor device, the oscillation frequency changes in response to variations in dielectric properties, charge and carrier density, dopant concentration, interface states, or any number of other variables that affect local capacitance. Over the past few years, researchers at Tohoku University have made several improvements in dielectric microscopy, the latest of which is a digital version called time-resolved SNDM (tr-SNDM). Here they describe their new technique and present an application in which it is used to acquire CV, dC/dV-V, and DLTS data from SiO2/SiC interface samples.

First Author Spotlight.

First Author Spotlight.

Stopping power measurement for proton therapy by combining proton radiography and X-ray CT

Exact information on the relative stopping power (RSP) of the high-energy proton in the human body is necessary to precisely control radiation dose and position in proton beam therapy. RSP has been estimated by converting the X-ray computed tomography (CT) information. However, it causes up to 5% uncertainty in the RSP measurements because of the fundamental difference between the X-ray and proton interaction. Therefore, this study investigates a scheme of the RSP distribution measurement in the human body with a combination of X-ray CT and proton radiography with beam injection to a single direction. We studied the accuracy of the RSP measurement using GEANT4 simulation with silicon trackers, crystal calorimeter, and proton beam. The RSP accuracy has been generally measured below 1% from the reference values for simple objects with multi cylindrical shapes. The simulation results present the requirements of a proton tracking system on the spatial resolution and the acquisition rate. We developed a tracking detector prototype consisting of double-sided silicon strip detectors and amplifier–shaper–discriminator LSI chips. We evaluated the performance with an 80 MeV proton beam in Cyclotron and Radioisotope Center, Tohoku University. It succeeded in reconstructing a proton trajectory with 160 kHz and fulfilled the requirements to realize the proposed scheme. Furthermore, this study describes the detailed study of the scheme of the RSP measurement and the beam test of the tracking system prototype.

Asamushi Research Center for Marine Biology, Graduate School of Life Sciences, Tohoku University

Asamushi Research Center for Marine Biology, Graduate School of Life Sciences, Tohoku University

Analysis on unidentified cases in which dental information was collected from 2014 to 2019 in Miyagi Prefecture, Japan

This study aimed to summarize the characteristics of unidentified cases in which dental information was collected during 2014–2019 in Miyagi Prefecture and to discuss the challenges and social characteristics of dental identification in routine forensic work. Cases were selected and examined from the database of dental charts collected at Tohoku University and the database of the Miyagi Prefectural Police. The annual percentage of cases with matched dental findings ranged from 19.2 − 37.1%, and 80.6% of the cases were identified within four days using dental information. The most common age group was the 50–70 s. Males were more common in the 20–70 s, whereas females were more frequent in the 80–90 s age group. Utilization of dental information was lower for cases involving young people and those over 90 years of age. The number of unidentified cases and unspecified death cases in the central block was significantly higher than other regions. However, there were no significant differences in sex, age, and season between each region. Spearman’s rank-order analysis of the unspecified deaths showed a strong correlation with the monthly average temperature (ρ = 0.89, p < 0.01).Within the limitations of this study, the results provide valuable information on the long-term progress of routine dental identification work and could be useful as a reference for a statistical survey. Future research must examine the role of dental information in forensic identification by exploring the role of more specific background characteristics among autopsy cases.

Life and Times of Akira Matsuzawa: In his own words

I graduated with a master&#x2019;s degree in electronics from the Graduate School of Engineering at Tohoku University in March 1978 and joined Matsushita Electric Industrial Co., Ltd. (currently Panasonic) in April of the same year. After one year of training for new employees, I was assigned to the semiconductor-development division of the Central Research Laboratory, and in April 1979, I started to work as an IC designer. My role was to develop ICs to realize digital video and TV systems, rather than to contribute to the semiconductor business.