Crystal Chemistry and Magnetic Properties of Manganese Zinc Alloy "YMn2Zn20" Comprising a Mn Pyrochlore Lattice

The chemical composition, crystal structure, and magnetic properties of a manganese zinc alloy with an ideal composition of YMn2Zn20, which comprises a pyrochlore lattice made of Mn atoms, are reported. The compound is stable only when In or Al is partially substituted for Zn. We have determined the actual chemical formula as YMn2+dZn20-x-dMx, with M = In or Al, and have identified the characteristic preferences with which the incorporated M and excess Mn atoms occupy the three crystallographic sites for Zn atoms. The Mn atoms in the pyrochlore lattice possess small magnetic moments that interact with each other antiferromagnetically but exhibit no long-range order above 0.4 K, probably owing to the geometrical frustration of the pyrochlore lattice. As a result, the effective mass of the conduction electrons is considerably enhanced, as observed in the related pyrochlore-lattice compounds (Y,Sc)Mn2 and LiV2O4. However, the presence of excess Mn atoms with large localized magnetic moments comparable to spin 5/2 tends to mask the inherent magnetism of the pyrochlore Mn atoms. It is suggested that "YMn2Zn18In2" with neither excess Mn atoms nor site disorder would be an ideal compound for further study.Comment: 19 pages, 18 figures, accepted for publication in J. Solid State Che

Structure Effect on Antioxidant Activity of Catecholamines toward Singlet Oxygen and Other Reactive Oxygen Species in vitro

The reactivity of catecholamine neurotransmitters and the related metabolites were precisely investigated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and reactive oxygen species. Catecholamines reacted immediately with DPPH radicals, their reactivity being stronger than that of ascorbic acid as a reference. Superoxide scavenging activities of catecholamines determined by WST-1 and electron spin resonance (ESR) spin trapping methods were also high. Whereas tyrosine, the dopamine precursor showed no reactivity toward superoxide. The reactivity toward singlet oxygen was evaluated by observing specific photon emission from singlet oxygen. The results revealed that reactivity of catecholamines was markedly higher than that of sodium azide, and catechin as catechol reference. The reaction of catecholamines and singlet oxygen was further studied by ESR using 55-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping reagent and rose bengal as photosensitizer. DMPO-OH signal of epinephrine was significantly small compared to other catecholamines, catechin, and 4-methylcatechol as a reference compound and was as small as that of tyrosine. The signal formation was totally dependent on singlet oxygen, and the presence of catechol compounds. These results indicated that epinephrine is the most potent singlet oxygen quencher than other catecholamines, and the secondary amino group in its alkyl side chain could play a role in unique singlet oxygen quenching property of epinephrine

Effects of Wnt-β-Catenin Signaling and Sclerostin on the Phenotypes of Rat Pheochromocytoma PC12 Cells

Pheochromocytomas and paragangliomas (PPGLs) are classified into 3 major categories with distinct driver genes: pseudohypoxia, kinase signaling, and Wnt-altered subtypes. PPGLs in the Wnt-altered subtype are sporadic and tend to be aggressive with metastasis, where somatic gene fusions affecting mastermind-like 3 (MAML3) and somatic mutations in cold shock domain containing E1 (CSDE1) cause overactivation of Wnt-β-catenin signaling. However, the relation between Wnt-β-catenin signaling and the biological behavior of PPGLs remains unexplored. In rat pheochromocytoma PC12 cells, Wnt3a treatment enhanced cell proliferation and suppressed mRNA expression of tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis, and dopamine secretion. We identified the expression of sclerostin in PC12 cells, which is known as an osteocyte-derived negative regulator for Wnt signaling-driven bone formation. Inhibition of endogenous Wnt pathway by XAV939 or sclerostin resulted in attenuated cell proliferation and increased TH expression. Furthermore, Wnt3a pretreatment suppressed bone morphogenetic protein (BMP)-induced Smad1/5/9 phosphorylation whereas BMPs enhanced sclerostin expression in PC12 cells. In the Wnt-altered subtype, the increased Wnt-β-catenin pathway may contribute the aggressive clinical behavior with reduced catecholamine production. Furthermore, upregulated expression of sclerostin by BMPs may explain the osteolytic metastatic lesions observed in metastatic PPGLs

Red thermoluminescence of enstatite from the Chainpur meteorite

For most ordinary chondrites feldspar is mainly responsible for thermoluminescence [TL], but in type 3 ordinary chondrites, especially those which are most primitive, other minerals are important. We observed red TL with a ∿660nm spectral peak in an ordinary chondrite, Chainpur (LL3.4). The mineral responsible for the red TL was identified as iron-free enstatite. Spatial distribution of TL and cathodoluminescence [CL] for the same specimen was also investigated, and it was found that the red TL areas corresponded to the high-sensitivity areas of red CL

Thermoluminescence of chondrules in primitive ordinary chondrites,Semarkona and Bishunpur

The spatial distribution of the induced thermoluminescence (TL) and TL glow curves of the primitive ordinary chondrites, Semarkona (LL3.0) and Bishunpur (LL3.1), were investigated over a wide range of wavelengths using a TL spatial distribution readout system. Although bulk samples of Semarkona and Bishunpur have very low TL sensitivity, individual chondrules show a wide variety of induced TL intensity and glow curve shape. Chondrules with anorthite-normative mesostases have especially high induced TL intensity, and their TL is produced at wavelengths >480nm, compared with <480nm for the sensitivity range of the usual TL measuring systems. Some of the metamorphism-dependent TL sensitivity of type 3 ordinary chondrite therefore results in changes in the spectrum of the light produced

Prediction of common hepatic artery catheter insertion based on celiac trunk morphology

PURPOSEThis study aimed to predict the ability to insert a 4–5 French (Fr) catheter insertion with a guidewire into the common hepatic artery (CHA) based on celiac trunk morphology.METHODSThis retrospective study included 64 patients who underwent balloon-occluded transcatheter arterial chemoembolization (n = 56), transcatheter arterial chemotherapy (n = 2), or were fitted with an implantable port system (n = 6) between June 2019 and December 2019 in our institution. The morphology of the celiac trunk was classified into three types (upward, horizontal, and downward) based on celiac angiography. The aortic–celiac trunk angle was measured on sagittal images of preprocedural contrast-enhanced computed tomography (CT). We reviewed whether a 4–5-Fr shepherd’s hook catheter could advance beyond the CHA using a 0.035-inch guidewire (Radifocus® Guidewire M; Terumo). Three patients were diagnosed with median arcuate ligament syndrome (MALS) based on the characteristic hook shape of the celiac artery on sagittal images of contrast-enhanced CT. The predictive ability of celiac angiography and preprocedural CT for CHA insertion success was evaluated. In unsuccessful cases, the balloon anchor technique (BAT) was attempted as follows: (1) a 2.7/2.8-Fr microballoon catheter (Attendant Delta; Terumo) was placed beyond the proper hepatic artery, and (2) the balloon was inflated as an anchor for parent catheter advancement.RESULTSUpward, horizontal, and downward celiac trunk types were noted in 42, 9, and 13 patients, respectively. The median CT angle was 122.83° (first quartile–third quartile, 102.88°–136.55°). Insertion in the CHA using the guidewire was successful in 56 of 64 patients (87.50%), and the success rate in the downward type was significantly lower than that in the upward type [42/42 (100%) vs. 7/13 (53.85%), P < 0.001]. The CT angle was significantly larger downward in the unsuccessful group than in the successful group (121.03° vs. 140.70°, P = 0.043). Celiac angiography had a significantly higher area under the curve (AUC) than preprocedural CT (AUC = 0.91 vs. AUC = 0.72, P = 0.040). All three cases of MALS showed unsuccessful CHA insertion. In all eight patients with unsuccessful insertion, the catheter could be advanced using the BAT [8/8 (100%)].CONCLUSIONCeliac angiography and preprocedural CT could predict CHA catheter insertion using a guidewire, and celiac angiography had high predictability. CT could detect MALS, a risk factor for unsuccessful CHA insertion