Preparation and certification of tea leaves reference material

Summary Tea leaves reference material was prepared and certified for elemental composition. Japanese green tea leaves were ground, sieved to pass a 80-mesh screen, blended and bottled. The prepared material satisfied the homogeneity criteria for a reference material. Trace element analysis of the material was carried out by flame and graphite furnace atomic absorption and inductively coupled plasma atomic emission spectrometry.Certification of the material was performed using the data obtained by various analytical techniques and certified values are provided for Al, Ca, Cd, Cu, K, Mg, Mn, Na, Ni, Pb and Zn. The elemental composition of the tea leaves reference material is considered typical of Japanese green tea leaves.     

Charge-transfer host complex with channel-like cavity using disubstituted-1,1′-bi-2-naphthol and benzylviologen

A novel charge-transfer (CT) host system is developed using CT complexes composed of rac-3,3′-dihydroxy-1,1′-bi-2-naphthol and 1,1′-dibenzyl-4,4′-bipyridinium dichloride. This CT host complex has a 1D channel-like cavity in which guest (MeOH and EtOH) molecules can be discharged and adsorbed. The color and DRS of the CT crystals change according to the presence of guest molecules in the host complex.     

A novel two-stage deep learning-based small-object detection using hyperspectral images

Optical Review - Hyperspectral imaging has drawn significant attention in recent years, and its application to object detection and classification is currently an important research topic. However,...     

The kernel for reasonable outcomes in a cooperative game

It is shown that the prekernel and the pre-nucleolus of a cooperative game coincide with the kernel and the nucleolus for the reasonable set of the game respectively.     

Distribution of metal chelates between aqueous and surfactant phases separated from a micellar solution of a nonionic surfactant

A dilute micellar solution of poly(oxyethylene) 4-nonylphenyl ether with oxyethylene units 7.5 (PONPE-7.5) was separated into two phases (aqueous and surfactant phases) at room temperature. The partition constants of several chelating reagents and their metal chelates between the two phases were determined at 293 K and ionic strength 0.1 (NaClO₄). The partition constants of the neutral metal chelates depend on the kind of metal ions and were considerably smaller than those expected from the regular solution theory. These facts suggested that the chelates were incorporated into a hydrocarbon environment in the surfactant phase, whereas the chelating reagents were distributed in the poly(oxyethylene) part of PONPE-7.5. A brief review was also presented on the analytical applications to the extraction of metal ions and organic compounds.     

Analysis of sugar epimers using mass spectrometry: N-acetyllactosamine-6,6'-disulfate and the 2'-epimer

Galbeta1-4GlcNAc-6,6'-disulfate and 2'-epimer corresponding to Galbeta1- 4ManNAc-6,6'-disulfate were distinguished by mass spectrometry by utilizing fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) methods. As for the steric information, negative-ion ESI mass spectrometry/mass spectrometry (MS/MS) provides the most extensive data, but FAB MS/MS also reveals detailed structural information of interest in our case, where MALDI MS is not yet fully equipped with post-source decay.     

Species-specific isotope dilution analysis of mono-, di,and tri-butyltin compounds in sediment using gas chromatography-inductively coupled plasma mass spectrometry with synthesized 118Sn-enriched butyltins

A species-specific isotope dilution (ID) method is described for the determination of mono-, di, and tri-butyltin compounds in sediment by gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS), where the mixture of 118Sn-enriched butyltin compounds synthesized in our laboratory was used as a spike. A correction method for the mass bias, a quantitative extraction of the butyltins from sediment, and an assay for the concentration of the standard solution for the reverse ID procedure were investigated to achieve a reliable ID analysis. The spike solution was added with tri-propyltin (TPrT), and the butyltins were extracted by mechanical shaking into acetic acid-tropolone-toluene. The extracted butyltins were ethylated with sodium tetraethylborate and measured by GC-ICP-MS. The mass bias correction factor for the butyltins was calculated with the measured area ratio of 120Sn/118Sn of TPrT in each chromatographic run, and the correction was carried out. The mass bias was well corrected with this in-run correction (the standard uncertainties of the corrected 120Sn/118Sn for the butyltins were in the range 0.03-0.45%, typically 0.25%, with triplicate measurement corresponding to 0.02-0.37% mass bias). The extraction efficiency of mono-butyltin (MBT) from sediment was improved by using tropolone-toluene as the solvent. Well-defined standard solutions for the reverse-ID procedure could be obtained by an assay for the purities of the natural abundance butyltin chloride reagents used for preparing the standard solutions. Overall uncertainties associated with the present method were estimated, where the sediment certified reference materials, PACS-2 and BCR 646, were analyzed. The uncertainty arising from the extraction was the main contributor to the overall uncertainties for MBT and di-butyltin (DBT) determinations, while with the case of tri-butyltin (TBT) determination the uncertainties arising from the purity of TBT chloride reagent used for preparing the standard solution was a large contributor to the overall uncertainties although the uncertainty arising from the extraction was also a main contributor. The analytical results of MBT, DBT, and TBT in both reference materials, except for MBT results in PACS-2, were in good agreement with the certified values in each. The result of MBT in PACS-2 (0.677 +/- 0.049 microg g(-1) as tin, mean +/- expanded uncertainty) was significantly higher than the certified value (0.45 +/- 0.05 microg g(-1)), but closely matched with the lately reported values (Rajendran, Tao, Nakazato and Miyazaki, Analyst, 2000, 125, 1757: 0.62 +/- 0.02 microg g(-1); Chiron, Roy, Cottier and Jeannot, J. Chromatogr. A, 2000, 879, 137: 0.634 +/- 0.082 microg g(-1); Alonso, Encinar, Gonzalez and Sanz-Medal, Anal. Bioanal. Chem., 2002, 373, 432: 0.64 +/- 0.04 microg g(-1). The present method is concluded to be reliable for the determination of MBT, DBT, and TBT in sediment.     

Development of a novel nucleoside analogue with S-type sugar conformation: 2′-deoxy-trans-3′,4′-bridged nucleic acids

Two novel trans-3′,4′-bridged nucleic acid (trans-3′,4′-BNA) monomers, one with a 3,5,8-trioxabicyclo[5.3.0]decane structure and the other with a 4,7-dioxabicyclo[4.3.0]nonane structure, were successfully synthesized from thymidine. The locked trans-fused ring structures of the nucleoside analogues were confirmed by X-ray crystallography, which also indicated that their furanose rings had a typical S-type conformation involving C_2′-endo or C_3′-exo sugar puckering, respectively, and the same ring conformation as that observed in the B-type helical structure of the DNA duplex.     

Certification of mono-, di-, and tributyltin compounds in marine sediment certified reference material by species-specific isotope dilution mass spectrometric analysis using synthesized <Superscript>118</Superscript>Sn-labeled butyltins

A new marine sediment reference material (NMIJ CRM 7301-a) for butyltins analysis was prepared and certified by the National Metrological Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). The original material of the sediment was collected at a bay near industrial activities in Japan. The sediment material was air-dried, sieved, homogenized, and packaged into 1,000 glass bottles (60 g each). Certification of NMIJ CRM 7301-a was carried out at NMIJ using two different types of species-specific isotope dilution mass spectrometry: isotope dilution–ethylation–gas chromatography/inductively coupled plasma mass spectrometry (GC/ICPMS) and isotope dilution–ethylation–gas chromatography/mass spectrometry (GC/MS). A mixture of ¹¹⁸Sn-enriched monobutyltin, dibutyltin, and tributyltin was synthesized in our laboratory and was used as a spike for both techniques. Certified values are given for tributyltin (0.044±0.004 mg kg^–1 as Sn), dibutyltin (0.056±0.006 mg kg^–1 as Sn, and monobutyltin (0.058±0.013 mg kg^–1 as Sn), being at lower levels than currently available sediment CRMs for the analysis of organotins.     

Creation of the nuclear alignment and theG-parity conservation law in weak nucleon currents

-ray angular distributions from nuclear spin aligned¹²B and¹²N were detected and the correlation coefficients were determined. From the comparison of these with the experimental weak magnetism term, it was concluded that the parity of the weak nucleon currents in the iso-spin space was strictly conserved.