Search

Highly sensitive detection method of dibenzyl disulfide (DBDS) in insulation oil was realized using solid phase extraction (SPE) with active alumina adsorbent followed by gas chromatography equipped with a mass spectrometry (GC-MS). The detection limit of DBDS is around 0.1 ppm. This method is also useful for detecting bibenzyl (BiBZ) and dibenzyl sulfide (DBS). The good relationship between the weight change of copper strip and BiBZ /DBS formation was obtained under heating with insulating oil containing DBDS and copper strip, so it was clarified that BiBZ and DBS are the byproducts of the copper sulfide generation with the chemical reaction between DBDS and copper. The chemical reaction formula between DBDS and copper was proposed based on the assumption that copper sulfide should be generated via Cu-DBDS complex. The temperature dependence of the weight change of copper strip before and after the heating in the insulating oil containing DBDS was quantitatively explained with the chemical reaction formula. Index Terms--Copper, copper compounds, oil insulation, paper insulation, sulfur, sulfur compounds, transformers, transformer oil, chromatography.

Effects of oil brand, temperature and atmosphere conditions on copper sulfide deposition on insulating paper were investigated by thermal aging test. Copper sulfide deposition occurred in a certain oil brand and dibenzyi disulfide (DBDS) was found in the oil. There was an incubation period observed before copper sulfide deposition occurred. Copper sulfide deposition was accelerated by temperature. The deposition rate after the incubation period became twice when the heating temperature was increased by approximately 10 [degrees]C. The incubation period and the deposition rate were the same at 140 [degrees]C whether the thermal aging test was done in air or nitrogen atmosphere. On the other hand, the incubation period in air was shorter than that in nitrogen at 120 [degrees]C. The deposition rate was not affected by atmosphere condition at 120 [degrees]C. Intermediate substances due to copper dissolution into oil are introduced to explain the incubation period and the atmosphere dependence of incubation period observed at 120 [degrees]C. Index Terms--Copper, copper compounds, oil insulation, paper insulation, sulfur, sulfur compounds, transformers.

The suppressive effect of triazole-based passivators such as 1,2,3-benzotriazole (BTA) and Irgamet 39[TM] (CIBA Specialty, Basel, Switzerland) on the deposition of copper sulfide on insulating paper in transformers and reactors was investigated by heating test with bare and paper-wrapped copper plates. Commercially available mineral oil meeting the specification of IEC 60296 was used. This oil contained 136 ppm wt./wt, of dibenzyl disulfide (DBDS). The deposition of copper sulfide occurred after 144 h of heating at 140 [degrees]C without these passivators. However, little deposition of copper sulfide occurred even after 432 h of heating when either of these passivators was added to the oil. The concentration of dissolved copper significantly decreased when either of these passivators was added to the oil, which reflects the formation of complex layers on the copper surface caused by the reaction between these passivators and copper. The complex layers were confirmed by time-of-flight secondary ion mass spectrometer (TOF-SIMS). The suppressive effect was derived from retarding copper from dissolving into the oil due to the reaction inhibition between DBDS and copper by the complex layers. The duration of these passivators can be determined by the durability of the complex layers. Index Terms--Copper, copper compounds, oil insulation, paper insulation, sulfur, sulfur compounds, transformers, transformer oil.

We report a rare case of hepatic adenomas (HA), in a 20-year-old Japanese girl treated for 6 years with anabolic androgens for aplastic anemia. In a review of the world literature using computer MEDLINE search, we found only 17 cases of androgen-induced HA published between 1975 and 1998 in the English-language literature. The patient was referred to us because of liver lesions detected during a follow-up examination for familial adenomatous polyposis. After being diagnosed with aplastic anemia at 14 years of age, she had been treated with oxymetholone (30 mg/day) for 6 years. Laboratory evaluation revealed normal liver function. Ultrasonography (US) and computed tomography (CT) demonstrated multiple liver lesions. Histopathological examinations of biopsied specimens from the liver tumor showed HA. After the patient was diagnosed with HA, oxymetholone was tapered off. Patients taking androgenic-anabolic steroids should be carefully monitored with US and CT and tumor markers should be measured. This report may be helpful in identifying the population who is at risk of developing hepatic sex hormone-related tumors. [ABSTRACT FROM AUTHOR]

Fipronil (FIP) is a phenylpyrazole insecticide that, along with neonicotinoid insecticides, is regularly used worldwide. Photodegradation of FIP in aqueous systems is thought mainly to involve the reaction of desulfinylation to give fipronil desulfinyl (FIP-desulfinyl); however, little is known about further degradation reactions. We investigated FIP photodegradation by analyzing photodegradation products by liquid chromatography and liquid chromatography high-resolution tandem mass spectrometry using an Orbitrap instrument. A wide range of products, including dechlorinated compounds, was detected, and the structures were identified. FIP-desulfinyl has previously been found to be an important and persistent FIP photodegradation product; however, we also found that FIP-desulfinyl was photochemically decomposed to a didechlorinated product via a monodechlorinated product. The main photodegradation pathway was probably similar to that of ethiprole, which has a similar skeleton. The photodegradation rate constant was 22.6 times lower for FIP-desulfinyl (0.00372 min -1 ) than FIP (0.0839 min -1 ). The photodegradation rate constant was lower for the newly found didechlorinated product (0.001 min -1 or below) than FIP-desulfinyl, suggesting that the product is persistent in aquatic environments and could be an important indicator of long-term FIP contamination., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Protein-protein interactions are essential in biological reactions and fundamental to cell-cell communication (e.g., the binding of secreted proteins, such as hormones, to cell membrane receptors) and the subsequent intracellular signal transduction cascade. Several studies have been extensively carried out on protein-protein interactions because they have the potential to resolve various problems in molecular biology. Biochemical methods, such as chemical cross-linking and immunoprecipitation, have long been used to analyze which proteins interact with each other. However, there are some problems, such as unphysiological states and non-specific binding, that require the development of more useful experimental methods. This chapter discusses the "proximity labeling (Proteomics)" analysis technique, which has been attracting attention in protein-protein interaction analysis in recent years and is used in many biological studies. "Membrane proximity labeling (proteomics)," which analyzes the interaction of cell membrane proteins, and "intracellular proximity labeling (proteomics)" will be explained in-depth., Competing Interests: Conflicts of interest The authors have no competing or financial interests to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

We report the migration of terephthalate and some low molecular weight organic compounds from poly(ethylene terephthalate) (PET) scraps in Milli-Q water and artificial seawater (ASW). The photochemical processes and the subsequent dark reactions were investigated using PET scraps obtained from postconsumer bottles of commercial non‑carbonated mineral water. Concentrations of terephthalate exponentially increased with irradiation time, reaching approximately 6-8 μmol L -1 in ASW after 80 h irradiation. The photochemical migrations of compounds related to terephthalate were also observed. Concentrations of terephthalate and related compounds reached higher concentrations in ASW than in Milli-Q water. After 80 h irradiation, two dark experiments were conducted: one on the solutions after irradiation without PET scraps, and the other on photochemically damaged PET scraps. In ASW in the dark without PET scraps, the terephthalate concentration increased, and concentrations of other compounds related to terephthalate also changed. The results suggested that terephthalate was generated by hydrolytic reaction in dark ASW from the scission products of PET which were generated during the irradiation of PET scraps. Photochemically damaged PET scraps released terephthalate and related compounds in the dark. The half-life of the photo-irradiated PET scraps in the dark is approximately 205 years. Our results show that PET bottles in marine environments can continuously release terephthalate and other low molecular weight organic compounds during the day at the sunny surface, at the dark ocean floor, and during the night., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Agrobacterium tumefaciens is a bacterial pathogen that causes crown gall disease on a wide range of eudicot plants by genetic transformation. Besides T-DNA integrated by natural transformation of plant vegetative tissues by pathogenic Agrobacterium spp., previous reports have indicated that T-DNA sequences originating from an ancestral Agrobacterium sp. are present in the genomes of all cultivated sweet potato ( Ipomoea batatas ) varieties analyzed. Expression of an Agrobacterium -derived agrocinopine synthase (ACS) gene was detected in leaf and root tissues of sweet potato, suggesting that the plant can produce agrocinopine, a sugar-phosphodiester opine considered to be utilized by some strains of Agrobacterium spp. in crown gall. To validate the product synthesized by Ipomoea batatas ACS (IbACS), we introduced IbACS into tobacco under a constitutive promoter. High-voltage paper electrophoresis followed by alkaline silver nitrate staining detected the production of an agrocinopine-like substance in IbACS1 -expressing tobacco, and further mass spectrometry and nuclear magnetic resonance analyses of the product confirmed that IbACS can produce agrocinopine A from natural plant substrates. The partially purified compound was biologically active in an agrocinopine A bioassay. A 16S ribosomal RNA amplicon sequencing and meta-transcriptome analysis revealed that the rhizosphere microbial community of tobacco was affected by the expression of IbACS . A new species of Leifsonia (actinobacteria) was isolated as an enriched bacterium in the rhizosphere of IbACS1 -expressing tobacco. This Leifsonia sp. can catabolize agrocinopine A produced in tobacco, indicating that the production of agrocinopine A attracts rhizosphere bacteria that can utilize this sugar-phosphodiester. These results suggest a potential role of IbACS conserved among sweet potato cultivars in manipulating their microbial community.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The triple-stranded metallohelicates 1 a,/1 b-3 a/3 b possessing internal guest binding cavities surrounded by calix[4]arene units were synthesized through coordination-driven self-assembly. UV/Vis titration experiments verified that the metallohelicates encapsulated N-methyl pyridinium cations bearing amino acid groups to form host-guest complexes. The guest chirality was transferred to the helicity of the helicates through the steric contact between the stereogenic center of the amino acid group and the metal cores. The (M) helicity was induced when guests the (R)-4--(R)-6 were accommodated within the cavities. The multiple guest complexation within the self-assembled helicates 2 a and 3 a displayed large positive cooperative effects, indicating that the first guest complexation preorganizes the rest of the cavities to facilitate a subsequent guest binding. This cooperativity results in the majority-rules effect in the chiral guest binding for 2 a and 3 a., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

It is well known that oil droplets in or on water exhibit spontaneous movement induced by surfactants, and this self-propulsion is regarded as an important factor in droplet-based models for a living cell. We report here an oil-droplet system spontaneously producing amino acid-based surfactants, which are then utilized for the droplets' self-propulsion. Thus this system is an active system capable of producing the fuel for the propulsion by itself, which can be used as a conceptual model for cell metabolism.

Nature precisely manipulates primary monomer sequences in biopolymers. In synthetic polymer sequences, this precision has been limited because of the lack of polymerization techniques for conventional polymer synthesis. Engineering the primary monomer sequence of a polymer main chain represents a considerable challenge in polymer science. Here, we report the development of sequence-controlled supramolecular terpolymerization via a self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs. Complementary biscalix[5]arene-C 60 , bisporphyrin-trinitrofluorenone (TNF), and Hamilton's bis(acetamidopyridinyl)isophthalamide-barbiturate hydrogen-bonding host-guest complexes are separately incorporated into heteroditopic monomers that then generate an ABC sequence-controlled supramolecular terpolymer. The polymeric nature of the supramolecular terpolymer is confirmed in both solution and solid states. Our synthetic methodology may pave an avenue for constructing polymers with tailored sequences that are associated with advanced functions.Nature can precisely control monomer sequences in biopolymers, but this is somewhat problematic in the formation of synthetic polymers. Here the authors show sequence-controlled supramolecular terpolymerization via self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs.