Implementation of optically simulated luminescent dosimeter for quality control of gamma ray dose of an accelerator-based neutron source.

BACKGROUND: Neutron beams utilized for performing BNCT are composed of a mixture of neutrons and gamma rays. Although much of the dose delivered to the cancer cells comes from the high LET particles produced by the boron neutron capture reaction, the dose delivered to the healthy tissues from unwanted gamma rays cannot be ignored. With the increase in the number of accelerators for BNCT, a detector system that is capable of measuring gamma ray dose in a mixed neutron/gamma irradiation field is crucial. Currently, BeO TLDs encased in quartz glass are used to measure gamma ray dose in a BNCT irradiation field. However, this type of TLD is no longer commercially available. A replacement dosimetry system is required to perform the recommended ongoing quality assurance of gamma ray measurement for a clinical BNCT system. PURPOSE: The purpose of this study is to evaluate the characteristics of a BeO OSLD detector system under a mixed neutron and gamma ray irradiation field and to assess the suitability of the system for routine quality assurance measurements of an accelerator-based BNCT facility. METHODS: The myOSLD system by RadPro International GmbH was evaluated using the accelerator-based neutron source designed for clinical BNCT (NeuCure BNCT system). The readout constancy, linearity, dose rate effect, and fading effect of the OSLD were evaluated. Free-in-air and water phantom measurements were performed and compared with the TLD results and Monte Carlo simulation results. The PHITS Monte Carlo code was used for this study. RESULTS: The readout constancy was found to be stable over a month-long period and similar to the TLD results. The OSLD readout signal was found to be linear, with a high coefficient of determination (R2 ≥ 0.999) up to a proton charge of 3.6 C. There was no significant signal fading or dose rate dependency. The central axis depth dose and off-axis dose profile measurements agreed with both the TLD and Monte Carlo simulation results, within one standard deviation. CONCLUSION: The myOSLD system was characterized using an accelerator system designed for clinical BNCT. The experimental measurements confirmed the OSLD achieved similar, if not superior to, the currently utilized dosimetry system for routine QA of an accelerator-based BNCT system. The OSLD system would be a suitable replacement for the current TLD system for performing routine QA of gamma ray dose measurement in a BNCT irradiation field.

Unusual Vibrational Coupling of the Schiff Base in the Retinal Chromophore of Sodium Ion-Pumping Rhodopsins.

A Schiff base in the retinal chromophore of microbial rhodopsin is crucial to its ion transport mechanism. Here, we discovered an unprecedented isotope effect on the C═N stretching frequency of the Schiff base in sodium ion-pumping rhodopsins, showing an unusual interaction of the Schiff base. No amino acid residue attributable to the unprecedented isotope effect was identified, suggesting that the H-O-H bending vibration of a water molecule near the Schiff base was coupled with the C═N stretching vibration. A twist in the polyene chain in the chromophore for the sodium ion-pumping rhodopsins enabled this unusual interaction of the Schiff base. The present discovery provides new insights into the interaction network of the retinal chromophore in microbial rhodopsins.

Characteristics of patients presenting with concomitant carpal tunnel syndrome at the initial diagnosis with rheumatoid arthritis.

OBJECTIVE: To investigate the clinical characteristics of patients who presented with concomitant carpal tunnel syndrome (CTS) at the initial diagnosis with rheumatoid arthritis (RA). METHODS: We analyzed patients with newly diagnosed RA at a single institution between 2012 and 2021. Patient demographic and laboratory data, the 2010 ACR/EULAR classification criteria, and the duration from the initial visit to RA diagnosis were compared between RA patients with concomitant CTS (RA with CTS group) and those without CTS (RA without CTS group). RESULTS: The study included 235 patients (157 females), of which 11 patients (4.7%) presented with CTS at the initial diagnosis with RA. In the RA with CTS group, the age was significantly higher (P = .033), all patients were female, and anti-cyclic citrullinated peptide antibody (ACPA) was negative, and the duration to RA diagnosis was longer than in the RA without CTS group. Among all RA with CTS patients, ultrasonography showed power Doppler signal-positive tenosynovitis in the carpal tunnel, which is not usually detected in idiopathic CTS. CONCLUSIONS: Patients with concomitant CTS at the initial diagnosis with RA were characterized by old age, female sex, and negative ACPA. Patients with symptoms of CTS should undergo ultrasonography for early diagnosis of RA.

Infectious in vitro transcripts from a cDNA clone of a Japanese gentian isolate of Sikte waterborne virus, which shows host-specific low-temperature-dependent replication.

Tombusviruses have been identified in several crops, including gentian virus A (GeVA) in Japanese gentian. In this study, we isolated another tombusvirus, Sikte waterborne virus strain C1 (SWBV-C1), from Japanese gentian. Although SWBV-C1 and GeVA are not closely related, SWBV-C1, like GeVA, showed host-specific low-temperature-dependent replication in gentian and arabidopsis. The use of in vitro transcripts from full-length cDNA clones of SWBV-C1 genomic RNA as inocula confirmed these properties, indicating that the identified genomic RNA sequences encode viral factors responsible for the characteristic features of SWBV-C1.

Breakup and deformation of a droplet falling in a miscible solution.

When a droplet with a higher density falls in a miscible solution, the droplet deforms and breaks up. The instability of a vortex ring, formed by droplet deformation during the falling process, causes the breakup. To determine the origin of the instability, the wavelengths and thicknesses of the vortex rings are investigated at the time when the instability occurs. The experimental results are almost in agreement with the calculated results for the Rayleigh-Taylor instability using the thickness of a higher-density solution. Furthermore, we performed simulations considering the torus shapes and circulations of the vortex ring. The simulations provided patterns similar to those observed experimentally for the breakup process, and showed that the circulations suppress the instability of the vortex ring. These results imply that the Rayleigh-Taylor instability plays a dominant role in the instability of vortex rings.

Allosteric Regulation of Unidirectional Spring-like Motion of Double-Stranded Helicates.

We report the unprecedented allosteric regulation of the extension and contraction motions of double-stranded spiroborate helicates composed of 4,4'-linked 2,2'-bipyridine (bpy) and its N,N'-dioxide units in the middle of ortho-linked tetraphenol strands. NMR and circular dichroism measurements and an X-ray crystallographic analysis along with theoretical calculations revealed that enantiomeric helicates contract and extend upon the binding and release of protons and/or metal ions at the covalently linked two binding bpy or N,N'-dioxide moieties without racemization, respectively, regulated by a cooperative anti-syn conformational change of the two bpy or N,N'-dioxide moieties. These anti-syn conformational changes that occurred at the linkages are amplified into a large-scale molecular motion of the helicates leading to reversible spring-like motions coupled with twisting in one direction in a highly homotropic allosteric fashion.