Highly deacetylated chitosan and its properties

A preparative method has been established for obtaining chitosan products which have a desired degree of deacetylation of up to virtually 100%. Effective deacetylation was attained by intermitently washing the intermediate product in water two or more times during the alkali treatment. The weight average molecular weight (M?_w) of the product, which was measured by gel permeation liquid chromatography, was about 5 × 10⁵ at the highest deacetylation of nearly 100%, and the degradation of the molecular chain was not so significant. Tensile strength of the wet film increased markedly with increasing degree of deacetylation, while the dry film did not show a corresponding significant increase of the tensile strength. In the infrared spectra of chitosan film new sharp bands appeared especially at the high degree of deacetylation. This was attributed to increased “crystallization” brought about by high deacetylation.     

Methotrexate induced pneumatosis intestinalis under hemodialysis patient

Pneumatosis intestinalis (PI) is a rare disorder characterized by the gas within the intestinal mucosa. This is the first report methotrexate (MTX) induced PI under hemodialysis (HD) patient. A 46‐year‐old man suffered rheumatoid arthritis and underwent HD at local HD center. After the initial induction of MTX, the patient showed epigastralgia and diarrhea. He was referred to our hospital and abdominal computed tomography showed significant large intestinal edema and free intraperitoneal air consistent with PI. Physicians should aware that MTX is contraindication drug for chronic kidney disease and high‐flux HD may decrease MTX toxicity and oxidative stress, improving PI.     

Novel Frequency-Domain Multiplexing MKID Readout for the LiteBIRD Satellite

The satellite LiteBIRD (Light satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) is being designed to detect the B-mode polarization of the cosmic microwave background radiation. LiteBIRD will carry about 2,000 detectors for measurements in five bands (60, 80, 100, 150, and 220 GHz). Microwave kinetic inductance detectors (MKIDs) that can be multiplexed in a single readout line are suitable for the large focal plane detector array. We develop an MKID readout system for LiteBIRD to monitor the amplitude, phase, and resonant frequency of each MKID resonator simultaneously and follow movements of the resonant frequency caused by changes in the input radiation intensity. This mechanism enables us to have a larger dynamic range for the MKIDs, compared with a system that monitors the amplitude and phase on the resonant frequency. We also propose an MKID having a half-wavelength resonator. This MKID transmits the resonant microwave signal from one feedline to another. It can offer clear microwaves passing through the resonators, even if the coupling and internal quality factors are mismatched. With this MKID, our readout system can track resonance frequency changes much more easily. We present the status of the readout system development and demonstrate the performance with the half-wavelength MKID.     

Development of an electromagnetic helical microwiggler withpermanent magnets

An electromagnetic helical microwiggler with three poles per period, employing permanent magnets to suppress leakage flux in the vicinity of the gap, has been developed. The wiggler is embedded in a double-walled vacuum chamber with a water jacket for heat removal. The field profile consists of a 30-period-long uniform-field section terminated at both ends with 5-period-long tapered fields. A peak on-axis field of 3.0 kG was achieved with a period of 7.9 mm and a gap diameter of 4.6 mm. An optimal sorting technique was applied to the permanent magnets to minimize variations in the peak field amplitude. Based on measurements of the test wiggler, rms amplitude variations of 1.4% and 2.6% in, respectively, the horizontal and vertical field amplitudes were attained     

Ultra intense glass laser system and laser–plasma interactions

The 30 TW GEKKO MII short pulse laser (25 J in 0.71 ps at 1 μm) is completed and is used for fast ignitor and particle accelerator research. The photon pressure of the laser at 10¹⁷-10¹⁸ W/cm² pushed the critical and quarter critical density plasmas forward, resulting in the strong red shifts of the second (2ω₀) and three-halves (3ω₀/2) harmonic emissions backscattered from CH or CD planes. A few hundred keV proton and deuteron emissions are also observed from CD planes.     

Surface-active properties and thermal behavior of S-alkylthio-carboxylic acids and their potassium salts

S-Alkylthiocarboxylic acids and their potassium salts were prepared by photoaddition of α-olefins (C₁₀, C₁₂, and C₁₄) with mercapto carboxylic acids such as thiomalic acid, thiopropionic acid, and thioglycolic acid. The physicochemical solution properties and thermal stabilities for three series of thiosurfactants were evaluated. S-Alkylthiocarboxylic acids that contain bridged S-bonds provide excellent thermally stable surfactants, and their alkaline salts exhibit good surface activity.