Black egg or “Kuro-Tamago”, is a well-known souvenir of Owakudani fumarole area of Hakone volcano in Japan. The eggs, which were originally ordinary chicken eggs boiled in a certain natural hot water pond in the area, literally have a black surface, which is formed by some hydrothermal chemical reaction of the hot water in the pond. However, its black component has not yet been determined, although it has been explained as iron sulfide formed on the surface of the egg shell. The black color on the surface eventually changed to a brownish color when left to stand within days scale. The observed phenomena would be problematic for the explanation so far, since iron sulfide is relatively stable in atmospheric air. In this study, we successfully isolated the exterior black film material covering the egg shell in the solid state by immersing it in citric acid solution. We conducted various chemical analysis on the black film material and determined significant amounts of carbon (C), nitrogen (N) and sulfur (S) together with protein-like substances, while no significant iron sulfide was indicated. Given the high carbon and nitrogen contents with biogenic amino acids and fatty acids, the black component may have been produced by the Maillard reaction in the hydrothermal environment. The high sulfur content also suggests the formation of high molecular weight organic polymers by sulfur-mediated cross-linking reactions on the exterior of the egg shell.
Nano/micropore devices have been used as powerful tools to evaluate a wide range of particles at a single-particle level in a non-destructive and label-free manner. In this paper, single-particle detection and capture using low thickness-to-diameter aspect ratio pores are introduced. In addition, virus identification using artificial intelligence is presented. This work enables the discrimination of virus species with high accuracy owing to the comprehensive utilization of various feature parameters in ionic current signals using machine learning. Moreover, in terms of waveform-feature enhancement, the focus was on the development of functional nanopores that have the ability to recognize analytes. In this research, peptide probes were attached to nanopores, and molecular interaction between the analyte and probes provided selective prolongation of dwell time at a pore. These methodologies offer the prospect of a novel application in single-particle analysis.
An original gas analysis technology using quantum cascade lasers (QCLs) and infrared laser absorption modulation (IRLAM) has been developed and commercialized successfully. IRLAM enables fast concentration calculation with high measurement accuracy by extracting features related to a target component, interference components, and disturbance effects from the gas absorption signal of the sample gas. In the IRLAM method, the QCL operating wavelength is modulated around the absorption peak of the target gas to obtain an absorption-modulated signal. Then, the features are obtained by correlation (inner product) between the absorption-modulated signal and feature reference signals prepared in advance to extract information important for concentration determination. The concentration of the target gas is determined from the relationship of the features. Compared to conventional methods such as curve fitting for absorption spectra, since the number of variables used in the concentration calculation process can be significantly reduced, the calculation time can be dramatically shortened. This enables highly accurate real-time analysis while fully eliminating not only interfering gas influences but also various disturbance factors that affect measurement accuracy, such as laser wavelength drift and spectral broadening due to changes in the composition ratio of coexisting gases. Combined with QCLs manufactured in-house and a Herriottt cell with a unique structure to this concentration calculation algorithm, a practical gas analyzer using QCLs has been completed. The use of IRLAM has greatly expanded expanding the industrial application range of gas analysis by laser absorption spectroscopy, realizing the world’s first QCL-based on-board exhaust gas measurement, real-time monitoring of petrochemical processes, and in-line measurement of semiconductor processes.
Luminescent chromisms, which change their luminescence by external stimuli or environmental changes, have attracted much attention as a means of detecting invisible stimuli in a clear and simple manner. In particular, assembly-induced luminescent chromisms can flexibly respond to weak and gentle stimuli, thus, many studies have been reported in recent years. However, strategic design guidelines for assembly-based chromism still remain a challenge. The author has focused on the design of luminescent chromism based on the control of intermolecular interactions of self-assembled platinum(II) complexes, and has successfully developed various chromic materials. In particlar, proposed in this paper is the concept of designing intermolecular interactions and luminescent chromisms using counterions as a means of designing metastable and transient states in a more convenient and strategic manner. In this paper, first, the principle of luminescent chromism based on changes in the intermolecular assembly structure and the research trends to date are reviewed, and then, the author’s current research on the development of design principles for luminescent chromism are briefly introduced.
A novel endotoxin detection method was developed that combines a bioluminescence method using a high-luminant mutant luciferase and a lysate reaction. This method reached the detection limit of 0.0005 EU mL−1 in a 15-min duration. A salt-resistant mutant luciferase was developed whose sensitivity was not decreased by sodium chloride (NaCl) in dialysate; it was applied to the endotoxin analyzer for dialysate measurement. It was useful for dialysate measurement with a detection limit of 0.0003 EU mL−1 at 20 min and exhibited other properties under dialysis conditions. A thermostable luciferase was also developed and applied to a single-reaction type endotoxin analyzer. The detection limit was 0.001 EU mL−1 for 10 min, enabling a more rapid endotoxin detection. This novel endotoxin detection method has rapidly been becoming popular in the field of dialysate measurement because of its excellent features.
This paper describes the separation and determination of acetylsalicylic acid (aspirin, AP) and its related compounds by HPLC employing various core-shell (CS) type reversed-phase columns. Among seven CS type columns, large retention was observed in a pentabromobenzyl (PBr) type column, on the other hand, cyanopropyl (CN) type column gave low retention. For the elution order of eleven compounds investigated, caffeine retained in a PBr column and a Biphenyl column compared with those in other columns, showing effective π–π interaction. Retention order of acetylsalicylic acid and its decomposed compound salicylic acid (o-SA) was reversed in a RP-Amide column, showing effective electrostatic interaction between the column and the analyte. From the investigation of each CS column selectivity, a Biphenyl column was selected for the fast assay of Aspirin tablets due to the largest resolution between AP and o-SA. Under the HPLC conditions of a mobile phase, acetonitrile 30 % and 0.05 mol L−1 phosphate buffer (pH 3.0), a Biphenyl column, and ethenzamide as an internal substance (IS), a fast determination of AP in tablets by an IS method was successfully achieved within 2.5 min. Stability of AP changed dosage form (suspension in water) and AP suspension mixed with other suspended medicine Magmitt (MgO) was evaluated by the method. After storage for 30 min at room temperature, around 20 % AP was decomposed to o-SA in the mixed suspension medicine, indicating the loss of AP effectiveness (platelet aggregation inhibitory activity).
A new analytical method using GC-Orbitrap-HRMS was developed for the identification and quantification of volatile per- and polyfluoroalkyl substances (PFAS) in ambient air samples. Thirty-six volatile PFAS and halogenated organic compounds in ambient air samples, which were collected using nano particle and gas sampler (NS20) in Japan and China in 2019 and 2020, were successfully analyzed by the GC-Orbitrap-HRMS method. This is the first study to measure volatile PFAS such as fluorotelomer iodides (FTI), perfluoroalkyl diiodide (PFADiI), fluorotelomer acrylates (FTAC), fluorotelomer methacrylates (FTMAC), bromopentafluorobenzene (BPFB) and 1-bromo-3,5-bis(trifluoromethyl)benzene (BTFMBB), in the ambient air samples using GC-Orbitrap-HRMS. In addition, we examined matrix effects that prevent accurate quantification of volatile PFAS in ambient air samples, and significant matrix effects were observed in MS scanning. The selection of analysis mode is one of the important parameters for GC-Orbitrap-HRMS. This technique will facilitate understanding the kinetics of PFAS in ambient air.
We installed a lab-based X-ray absorption spectrometer for structural analysis of battery materials. For issues of conventional equipment, we made modifications to the optical system to improve the measurement accuracy and sensitivity. In addition, we established an original measurement protocol to enhance the accuracy and reliability of spectra. In this paper, we present an overview of the equipment and preliminary results of a few metal samples used as battery materials by both transmission and fluorescence methods. By optimizing the measurement conditions including sample thickness and concentration, results comparable to synchrotron radiation were obtained for Co and NiO, confirming the high versatility and potential of laboratory-based X-ray absorption spectroscopy.