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Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2-9 MeV C60 fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which π-bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS). Since the melting transition is not induced in diamond at atmospheric pressure, conventional inelastic thermal spike calculations cannot be applied. Two-temperature molecular dynamics simulations succeeded in the reproduction of both the track formation under MeV C60 irradiations and the no-track formation under GeV monoatomic ion irradiations.
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OBJECTIVES: To describe the diagnostic findings, surgical technique and outcomes in seven pugs with thoracolumbar vertebral instability due to articular process anomalies. MATERIALS AND METHODS: Records (2010 to 2019) of pugs with thoracolumbar vertebral instability associated with articular process anomalies that underwent decompressive laminectomy and vertebral stabilisation were reviewed. Data on preoperative and postoperative neurologic status, diagnostic findings, surgical techniques and outcomes were retrieved. RESULTS: Seven dogs were presented with ambulatory or non-ambulatory paraparesis. Caudal articular process anomalies (three dogs) and concomitant cranial and caudal articular process anomalies (four dogs) were noted. Myelography (six dogs) or magnetic resonance imaging (one dog) showed none to severe spinal cord compression. Dynamic myelography in six dogs demonstrated nine distinct sites of spinal cord dimension reduction positioned in extension and/or flexion (mean reduction: 16.0%, range: 8.5 to 24.0%). These dynamic compressions were located at sites with articular process anomalies (seven sites) and sites with no articular process anomalies (two sites). Vertebral instability was confirmed by intraoperative spinal manipulation in all dogs. All dogs remained ambulatory with improved (five dogs) or static (two dogs) neurological deficits at the last follow-up (median: 16 months; range: 1.5 to 66 months). CLINICAL SIGNIFICANCE: Dynamic myelography and/or intraoperative spinal manipulation demonstrated vertebral instabilities at sites with or without articular process anomalies on imaging. Decompressive laminectomy with vertebral stabilisation resulted in long-term neurological improvement in most dogs.
Assuntos
Doenças do Cão , Compressão da Medula Espinal , Animais , Doenças do Cão/diagnóstico por imagem , Doenças do Cão/cirurgia , Cães , Vértebras Lombares , Imageamento por Ressonância Magnética/veterinária , Compressão da Medula Espinal/diagnóstico por imagem , Compressão da Medula Espinal/cirurgia , Compressão da Medula Espinal/veterinária , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/cirurgiaRESUMO
Band-gap engineering is one of the fundamental techniques in semiconductor technology and also applicable in next generation spintronics using the spin degree of freedom. To fully utilize the spintronic materials, it is essential to optimize the spin-dependent electronic structures in the operando conditions by applying magnetic and/or electric fields. Here we present an advanced spectroscopic technique to probe the spin-polarized electronic structures by using magnetic circular dichroism (MCD) in resonant inelastic soft X-ray scattering (RIXS) under an external magnetic field. Thanks to the spin-selective dipole-allowed transitions in RIXS-MCD, we have successfully demonstrated the direct evidence of the perfectly spin-polarized electronic structures for the prototypical halfmetallic Heusller alloy [Formula: see text]. RIXS-MCD is a promising tool to probe the spin-dependent carriers and band-gap induced in the buried magnetic layers in an element specific way under the operando conditions.
RESUMO
Damaged regions of cylindrical shapes called ion tracks, typically in nano-meters wide and tens micro-meters long, are formed along the ion trajectories in many insulators, when high energy ions in the electronic stopping regime are injected. In most cases, the ion tracks were assumed as consequences of dense electronic energy deposition from the high energy ions, except some cases where the synergy effect with the nuclear energy deposition plays an important role. In crystalline Si (c-Si), no tracks have been observed with any monomer ions up to GeV. Tracks are formed in c-Si under 40 MeV fullerene (C60) cluster ion irradiation, which provides much higher energy deposition than monomer ions. The track diameter decreases with decreasing the ion energy until they disappear at an extrapolated value of ~ 17 MeV. However, here we report the track formation of 10 nm in diameter under C60 ion irradiation of 6 MeV, i.e., much lower than the extrapolated threshold. The diameters of 10 nm were comparable to those under 40 MeV C60 irradiation. Furthermore, the tracks formed by 6 MeV C60 irradiation consisted of damaged crystalline, while those formed by 40 MeV C60 irradiation were amorphous. The track formation was observed down to 1 MeV and probably lower with decreasing the track diameters. The track lengths were much shorter than those expected from the drop of Se below the threshold. These track formations at such low energies cannot be explained by the conventional purely electronic energy deposition mechanism, indicating another origin, e.g., the synergy effect between the electronic and nuclear energy depositions, or dual transitions of transient melting and boiling.
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Modification of the gap at the Dirac point (DP) in axion antiferromagnetic topological insulator [Formula: see text] and its electronic and spin structure have been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation at various temperatures (9-35 K), light polarizations and photon energies. We have distinguished both large (60-70 meV) and reduced ([Formula: see text]) gaps at the DP in the ARPES dispersions, which remain open above the Neél temperature ([Formula: see text]). We propose that the gap above [Formula: see text] remains open due to a short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for the "large gap" sample and apparently significantly reduced effective magnetic moment for the "reduced gap" sample. These observations can be explained by a shift of the Dirac cone (DC) state localization towards the second Mn layer due to structural disturbance and surface relaxation effects, where DC state is influenced by compensated opposite magnetic moments. As we have shown by means of ab-initio calculations surface structural modification can result in a significant modulation of the DP gap.
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We report the elongation of embedded Au nanoparticles (NPs) in three different matrices, i.e. amorphous carbon (a-C), crystalline indium tin oxide (InxSn1-xOz; ITO) and crystalline calcium fluoride (CaF2), under irradiations of 4 MeV C60 + cluster ions and 200 MeV Xe14+ ions. Under 4 MeV C60 cluster irradiation, strong sputtering is induced in CaF2 layer so that the whole the layer was completely lost at a fluence of 5 × 1013 ions cm-2. Au NPs were partly observed in the SiO2, probably due to the recoil implantation. Amorphous carbon (a-C) layer exhibits low sputtering loss even under 4 MeV C60 irradiation. However, the elongation in a-C layer was low. While the ITO layer showed a certain decrease in thickness under 4 MeV C60 irradiation, large elongation of Au NPs was observed under both 4 MeV C60 and 200 MeV Xe irradiation. The ITO layer preserved the crystallinity even after large elongation was induced. This is the first report of the elongation of metal NPs in a crystalline matrix.
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This study reports that high fluence fullerene ion (C60+) irradiation of 1-6 MeV, which was made possible by a new-type of high-flux ion source, elongates metal nanoparticles (NPs) in amorphous SiO2 as efficiently as swift heavy ions (SHIs) of 200 MeV Xe14+, i.e., two orders of the magnitude higher energy ions. Comparing the irradiation effects induced by both the beams, the stopping processes of C60 ions in SiO2 are discussed in this paper. Despite of having almost the same elongation efficiency, the C60+ irradiation induced ~10 times more efficient sputtering due to the clustering enhancement and/or the synergy effect. Ion tracks of ~10.4 nm in diameter and 60-80 nm in length were observed in crystalline SiO2 under 4 MeV C60 irradiation. While the track diameter was comparable to those by SHIs of the same electronic stopping, much shorter track lengths than those predicted by a rigid C60 molecule model indicates that the fragmentation occurred due to nuclear collisions. The elongation of the metal NPs was induced only down to the depth where the tracks were observed but not beyond.
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A new kind of magnetically-doped antiferromagnetic (AFM) topological insulators (TIs) with stoichiometry Bi1.09Gd0.06Sb0.85Te3 has been studied by angle-resolved photoemission spectroscopy (ARPES), superconducting magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD) with analysis of its electronic structure and surface-derived magnetic properties at different temperatures. This TI is characterized by the location of the Dirac gap at the Fermi level (EF) and a bulk AFM coupling below the Neel temperature (4-8 K). At temperatures higher than the bulk AFM/PM transition, a surface magnetic layer is proposed to develop, where the coupling between the magnetic moments located at magnetic impurities (Gd) is mediated by the Topological Surface State (TSS) via surface Dirac-fermion-mediated magnetic coupling. This hypothesis is supported by a gap opening at the Dirac point (DP) indicated by the surface-sensitive ARPES, a weak hysteresis loop measured by SQUID at temperatures between 30 and 100 K, XMCD measurements demonstrating a surface magnetic moment at 70 K and a temperature dependence of the electrical resistance exhibiting a mid-gap semiconducting behavior up to temperatures of 100-130 K, which correlates with the temperature dependence of the surface magnetization and confirms the conclusion that only TSS are located at the EF. The increase of the TSS's spectral weight during resonant ARPES at a photon energy corresponding to the Gd 4d-4f edge support the hypothesis of a magnetic coupling between the Gd ions via the TSS and corresponding magnetic moment transfer at elevated temperatures. Finally, the observed out-of-plane and in-plane magnetization induced by synchrotron radiation (SR) due to non-equal depopulation of the TSS with opposite momentum, as seen through change in the Dirac gap value and the kâ¥-shift of the Dirac cone (DC) states, can be an indicator of the modification of the surface magnetic coupling mediated by the TSS.
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To identify the precise molecular processes to induce DNA lesions, we attempt a novel spectroscopy of X-ray induced luminescence (XIL) using soft X-ray synchrotron radiation, which is a non-destructive analysis of the reaction intermediates in the elementary reaction pathway of damage induction and self-organized restoration. Using a liquid micro-jet technique to introduce aqueous samples in a vacuum chamber, we measure UV-visible luminescence from nucleotide solution as a function of the soft X-ray energy from the nitrogen to oxygen K-edge region. The XIL intensities for the nucleotide solutions are significantly enhanced in the soft X-ray region (410-530 eV) which is ascribed to the K-shell excitation/ionization of nitrogen atoms in the nucleobases. Furthermore, the XIL spectra do not show any signature of X-ray absorption near-edge structure (XANES) of the nucleobases. This is because the luminescence intensities collected from the integral area of the micro-jet only reflect the quantum yield of luminescence of the absorbed X-ray into UV-visible light irrespective of the absorption cross sections, i.e. of XANES. Thus the present result is the first evidence of luminescence as a result of X-ray absorption of aqueous nucleotides.
Assuntos
DNA/química , DNA/efeitos da radiação , Desoxirribonucleotídeos/química , Desoxirribonucleotídeos/efeitos da radiação , Desenho de Equipamento , Concentração de Íons de Hidrogênio , Luminescência , Nitrogênio/química , Oxigênio/química , Síncrotrons , Água/química , Espectroscopia por Absorção de Raios XRESUMO
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Statistical analysis suggests that the data may be fabricated. Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings. Additionally, the Japanese Society of Anesthesiologists has recommended retraction of this article: http://www.anesth.or.jp/english/pdf/news20170925.pdf.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Statistical analysis suggests that the data may be fabricated. Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Statistical analysis suggests that the data may be fabricated. Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.
RESUMO
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Statistical analysis suggests that the data may be fabricated. Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings. Additionally, the Japanese Society of Anesthesiologists has recommended retraction of this article: http://www.anesth.or.jp/english/pdf/news20170925.pdf.
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Canine hepatocellular carcinoma (HCC) is the most common primary hepatic tumour in dogs. MicroRNA (miRNA) dysregulation has been reported in human HCC and shown to have diagnostic and prognostic value; however, there are no data on miRNA expression in canine HCC. The aim of the present study was to investigate differentially expressed miRNAs in canine HCC. Analysis of miRNA expression in canine HCC tissues and cell lines by quantitative reverse transcription PCR showed that miR-1, miR-122, let-7a, and let-7g were downregulated, whereas miR-10b and miR-21 were upregulated in canine HCC. MET is one of the target genes of miR-1. MET was upregulated in canine HCC at the gene and protein levels, and a significant correlation between the concomitant downregulation of miR-1 and upregulation of MET was observed. Fast/intermediate-proliferating canine HCC cell lines had higher MET gene and protein expression levels than the slow-proliferating cell line. These findings suggest that miRNAs are differentially expressed in canine HCC, and that the miR-1/MET pathway may be associated with canine HCC cell proliferation.
Assuntos
Carcinoma Hepatocelular/veterinária , Doenças do Cão/genética , Neoplasias Hepáticas/veterinária , MicroRNAs/genética , Análise de Variância , Animais , Western Blotting/veterinária , Carcinoma Hepatocelular/genética , Linhagem Celular Tumoral , Cães , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
We report probability distributions of the number of secondary ions (SIs) emitted by sub-MeV C60 ion impacts on an organic polymer target and the characterization of their emission processes through the analysis of the distributions. The probability distributions were obtained by analyzing experimental SI counting data obtained by a time-of-flight SI mass spectrometer combined with pulsed primary ion beams, using an analytical model developed to derive the distributions from the experimental data. A series of probability distribution functions was investigated for ion impacts of C60 with sub-MeV energies (0.12-0.54 MeV), which can provide sufficient SIs per impact to determine the functions. Their complicated and undefined SI emission processes were characterized based on the determined functions.
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Adult T-cell leukemia (ATL) arises from a human T-cell leukemia virus type I (HTLV-I)-infected cell and has few therapeutic options. Here, we have uncovered a previously unrecognized role for a ubiquitin-editing enzyme A20 in the survival of HTLV-I-infected cells. Unlike in lymphomas of the B-cell lineage, A20 is abundantly expressed in primary ATL cells without notable mutations. Depletion of A20 in HTLV-I-infected cells resulted in caspase activation, cell death induction and impaired tumorigenicity in mouse xenograft models. Mechanistically, A20 stably interacts with caspase-8 and Fas-associated via death domain (FADD) in HTLV-I-infected cells. Mutational studies revealed that A20 supports the growth of HTLV-I-infected cells independent of its catalytic functions and that the zinc-finger domains are required for the interaction with and regulation of caspases. These results indicate a pivotal role for A20 in the survival of HTLV-I-infected cells and implicate A20 as a potential therapeutic target in ATL.
Assuntos
Caspase 8/genética , Proteínas de Ligação a DNA/genética , Proteína de Domínio de Morte Associada a Fas/genética , Vírus Linfotrópico T Tipo 1 Humano/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Leucemia-Linfoma de Células T do Adulto/genética , Proteínas Nucleares/genética , Adulto , Animais , Caspase 3/genética , Caspase 3/metabolismo , Caspase 7/genética , Caspase 7/metabolismo , Caspase 8/metabolismo , Morte Celular , Linhagem Celular , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/metabolismo , Proteína de Domínio de Morte Associada a Fas/metabolismo , Feminino , Regulação Leucêmica da Expressão Gênica , Vetores Genéticos , Células HEK293 , Interações Hospedeiro-Patógeno , Vírus Linfotrópico T Tipo 1 Humano/patogenicidade , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Lentivirus/genética , Leucemia-Linfoma de Células T do Adulto/metabolismo , Leucemia-Linfoma de Células T do Adulto/patologia , Leucemia-Linfoma de Células T do Adulto/virologia , Camundongos , Camundongos Endogâmicos NOD , Transplante de Neoplasias , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Carga Tumoral , Proteína 3 Induzida por Fator de Necrose Tumoral alfaRESUMO
AIM: In this study, we evaluated the carcinostatic effects of combined ascorbic acid (AsA) and a capacitive-resistive electric transfer (CRet) hyperthermic apparatus-induced hyperthermic treatment on Ehrlich ascites tumor (EAT) cells. MATERIALS AND METHODS: EAT cells were exposed to various AsA (0-10 mM) concentrations for 1 h; they subsequently underwent CRet treatment for 15 min at 42 °C. Cell viability was assessed by the WST-8 assay 24 h after the combined treatment. Reactive oxygen species involvement was evaluated using catalase and tempol; caspase-3/7 activation was determined by their fluorescent substrates; cell proliferation were estimated by time-lapse observation. The effect on the cell cycle was analyzed by flow cytometry. RESULTS: Combined AsA and CRet treatment synergistically suppressed cell viability compared with either treatment alone, and these synergistically carcinostatic effects were evident even at noncytotoxic concentrations of AsA alone (≤ 2 mM). The carcinostatic effects of combined AsA and CRet treatment were attenuated in a dose-dependent manner by catalase addition, but not by the superoxide anion radical scavenger tempol. Time-lapse observation revealed that combined AsA and CRet treatment activated caspase-3/7 at 10-24 h after treatment, accompanied by significant cell growth suppression. Cell cycle analysis revealed that the rate of sub-G1-phase (apoptotic) cells was drastically increased at 12 h and 24 h, and that the G2/M-phase cells gradually increased at 6-24 h after treatment. CONCLUSION: These results indicate that combined AsA and CRet treatment synergistically inhibits EAT cell growth through G2/M arrest and apoptosis induction via H2O2 generation at lower AsA concentrations; this carcinostatic effect cannot be exerted by AsA alone.