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BACKGROUND: Little is known about the occurrence of gustatory dysfunction (GD) in relation to different aetiologies of olfactory dysfunction (OD) as assessed by psychophysical chemosensory tests. The aim of this study was to analyse gustatory function in patients with OD and to investigate clinical factors associated with GD. METHODS: A total of 742 individuals who underwent both olfactory and gustatory function tests at a tertiary medical centre from November 2019 to March 2021 were retrospectively enrolled. Olfactory and gustatory function were assessed by the YSK olfactory and gustatory function tests, respectively. Patients with OD were classified into four groups according to the aetiology: sinonasal disease, post-infection OD (PIOD), post-traumatic OD (PTOD), and others. Secondary outcomes included age, sex, smoking history, and alcohol history. RESULTS: Among the 488 patients with OD, 93 (19.1%) showed GD and 395 (80.9%) had normal gustatory function. Only 25 (9.8%) among 254 individuals with normosmia showed GD. Analyses of these frequencies revealed a significant association between OD and GD. In addition, the taste score was significantly lower in patients with OD than individuals with normosmia. The frequency of GD was significantly higher in patients with PTOD (53.6%) than in those with OD of other aetiologies (sinonasal disease, 6.7%; PIOD, 13.0%; others, 24.4%). In the multivariate analysis, age >=5 years and PTOD were associated with a high frequency of GD among patients with OD. CONCLUSIONS: The current study show that GD is significantly associated with OD. In particular, GD is more common in patients with PTOD than in those with OD of other aetiologies.
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Transtornos do Olfato , Humanos , Pré-Escolar , Estudos Retrospectivos , Olfato , Distúrbios do Paladar/etiologiaRESUMO
Topological magnonic materials have attracted much interest because of the potential for dissipationless spintronic applications. Pyrochlore iridates are theoretically regarded as good candidates for designing topological magnon bands. However, experimental identification of topological magnon bands in pyrochlore iridates remains elusive. We explored this possibility in Y_{2}Ir_{2}O_{7} using Raman spectroscopy to measure both the single-magnon excitations and anomalous phonon shifts. From the single-magnon energies and tight-binding model calculations concerning the phonons, we determined the key parameters in the spin Hamiltonian. These confirm that Y_{2}Ir_{2}O_{7} hosts a nontrivial magnon band topology distinct from other pyrochlore iridate compounds. Our work demonstrates that pyrochlore iridates constitute a system in which the magnon band topology can be tailored and that Raman spectroscopy is a powerful technique to explore magnon band topology.
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Strong charge-spin coupling is found in a layered transition-metal trichalcogenide NiPS_{3}, a van der Waals antiferromagnet, from studies of the electronic structure using several experimental and theoretical tools: spectroscopic ellipsometry, x-ray absorption, photoemission spectroscopy, and density functional calculations. NiPS_{3} displays an anomalous shift in the optical spectral weight at the magnetic ordering temperature, reflecting strong coupling between the electronic and magnetic structures. X-ray absorption, photoemission, and optical spectra support a self-doped ground state in NiPS_{3}. Our work demonstrates that layered transition-metal trichalcogenide magnets are useful candidates for the study of correlated-electron physics in two-dimensional magnetic materials.
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This study investigated the effects of 9-week endurance cycling training on central fatigability and corticomotor excitability of the locomotor muscles. Fourteen healthy participants undertook three incremental fatiguing cycling tests to volitional exhaustion (EXH): (i) before training (PRE), (ii) after training at the same absolute power output as PRE (POSTABS) and (iii) after training at the same percentage of VÌO2max as PRE (POSTREL). At baseline (i.e. before cycling), every 5 min during cycling and immediately at EXH, a neuromuscular evaluation including a series of 5-s knee extensions at 100, 75 and 50% of maximal voluntary knee extension (MVC) was performed. During each contraction, transcranial magnetic and peripheral nerve stimuli were elicited to obtain motor evoked potential (MEP), silent period (SP) and compound muscle action potential (Mmax) and to calculate voluntary activation (VA). The MEP·Mmax-1 ratio recorded from vastus lateralis at 100 and 50% MVC did not show any difference between conditions. At 75% MVC, MEP exhibited significantly lower values in POSTABS and POSTREL compared to PRE at baseline (P = 0.022 and P = 0.011, respectively) as well as at 25% of time to EXH of PRE (P = 0.022) for POSTREL. No adaptations, either at baseline or during cycling, were observed for VA and SPs. In conclusion, endurance training may result in some adaptations in the corticomotor responses when measured at rest or with low level of fatigue, yet these adaptations do not translate into attenuation of central fatigue at a similar cycling workload or at exhaustion.
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Ciclismo/fisiologia , Treino Aeróbico/métodos , Córtex Motor/fisiologia , Fadiga Muscular/fisiologia , Tratos Piramidais/fisiologia , Adulto , Estimulação Elétrica , Eletromiografia , Nervo Femoral/fisiologia , Humanos , Masculino , Contração Muscular/fisiologia , Consumo de Oxigênio/fisiologia , Músculo Quadríceps/fisiologia , Estimulação Magnética Transcraniana , Adulto JovemRESUMO
PURPOSE: The adaptations induced by endurance training on the neuromuscular function remain under investigation and, for methodological reasons, unclear. This study investigates the effects of cycling training on neuromuscular fatigue and its peripheral contribution measured during and immediately after cycling exercise. METHODS: Fourteen healthy men performed a fatigue test before a 9-week cycling program (PRE) and two tests after training: at the same absolute power output as PRE (POSTABS) and based on the post-training maximal aerobic power (POSTREL). Throughout the tests and at exhaustion (EXH), maximal voluntary contraction (MVC) and peripheral fatigue were assessed in the quadriceps muscle by electrical nerve stimulation [single twitch (Pt); high-frequency doublet (Db100) and low-to-high-frequency ratio (Db10:100)]. RESULTS: Time to EXH was longer in POSTABS than PRE (34 ± 5 vs. 27 ± 4 min, P < 0.001), and POSTREL tended to be longer than PRE (30 ± 6 min, P = 0.053). MVC and peripheral fatigue were overall less depressed in POSTABS than PRE at isotime. At EXH, MVC and Db10:100 were similarly reduced in all sessions (-37 to - 42% and - 30 to - 37%, respectively). Db100 tended to be less depressed in POSTABS than PRE (-40 ± 9 vs. - 48 ± 16%, P = 0.050) and in POSTREL than PRE (-39 ± 9%, P = 0.071). Pt decreased similarly in POSTABS and PRE (-52 ± 16 vs. - 54 ± 16%), but POSTREL tended to be less depressed than PRE (-48 ± 14%, P = 0.075). CONCLUSIONS: This study confirms fatigue attenuation at isotime after training. Yet lower or similar fatigue at EXH indicates that, unlike previously suggested, fatigue tolerance may not be upregulated after 9 weeks of cycling training.
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Treino Aeróbico/métodos , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Força Muscular/fisiologia , Resistência Física/fisiologia , Músculo Quadríceps/fisiologia , Adulto , Eletromiografia , Exercício Físico/fisiologia , Teste de Esforço , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Adulto JovemRESUMO
The prototypical correlated metal Sr_{2}RhO_{4} was studied using optical and photoemission spectroscopy. At low energies and temperatures, the optical data reveal a complex, multicomponent response that on the surface points to an unconventional metallic state in this material. Via a comparison with photoemission, the anomalous optical response may be attributed to an unexpectedly strong interband transition near 180 meV between spin-orbit coupled bands that are nearly parallel along ΓX. This spin-orbit coupling effect is shown to occur in a number of related metallic ruthenates and explains the previously puzzling optical properties reported for these materials.
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Spin-phonon coupling mediated by single ion anisotropy was investigated using optical spectroscopy and first-principles calculations in the all-in-all-out pyrochlore magnet Cd_{2}Os_{2}O_{7}. Clear anomalies were observed in both the phonon frequencies and linewidths at the magnetic ordering temperature. The renormalization of the phonon modes was exceptionally large, signifying the presence of an unconventional magnetoelastic term from large spin-orbit coupling. In addition, the relative phonon frequency shifts show a strong correlation with the modulation of noncubic crystal field by the corresponding lattice distortion. Our observation establishes a new type of spin-phonon coupling through single ion anisotropy, a second-order spin-orbit coupling term, in Cd_{2}Os_{2}O_{7}.
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The slender shiner Pseudopungtungia tenuicorpa (Cypriniformes; Cyprinidae; Gobioninae) is an endangered freshwater fish species endemic to Korea. The current strategies for its conservation involve the study of population genetic characters and identification of management units. These strategies require suitable molecular markers to study genetic diversity and genetic structure. Here, we developed nine polymorphic microsatellite markers for P. tenuicorpa for the first time by applying an enrichment method from a size-selected genomic library. The developed microsatellite markers produced a total of 101 alleles (average 11.2). The observed and expected heterozygosities averaged 0.805 and 0.835, respectively. Among the nine identified markers, five markers showed successful amplification across five related Korean Gobioninae species. Thus, the microsatellite markers developed in this study will be useful to establish conservation strategies for both P. tenuicorpa and other related species.
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Cyprinidae/genética , Genética Populacional , Repetições de Microssatélites , Alelos , Animais , Conservação dos Recursos Naturais , Cyprinidae/classificação , Espécies em Perigo de Extinção , Genoma , Biblioteca Genômica , Heterozigoto , Reação em Cadeia da Polimerase , República da Coreia , Especificidade da EspécieRESUMO
UNLABELLED: We evaluated the correlation between central bone mineral density (BMD) and peripheral bone attenuation using lower extremity computed tomography (CT). A good correlation was found between lower extremity CT and central BMD suggesting that CT is useful for screening osteoporosis, and that peripheral bone attenuation adequately reflects central BMD. INTRODUCTION: This study aimed to evaluate the reliability and validity of CT as a screening tool for osteoporosis and to estimate the correlation between central BMD and peripheral bone attenuation using lower extremity CT. METHODS: In total, 292 patients who underwent a lower extremity, lumbar spine, or abdomen and pelvic CT scan within a 3-month interval of a dual-energy X-ray absorptiometry (DEXA) examination were included. Following reliability testing, bone attenuation of the L1, L2, L3, L4, femoral head, femoral neck, greater trochanter, distal femur, proximal tibia, distal tibia, and talus was measured by placing a circular region of interest on the central part of each bony region on a coronal CT image. Partial correlation was used to assess the correlation between CT and DEXA after adjusting for age and body mass index. RESULTS: In terms of reliability, all bone attenuation measurements, except the femoral neck, showed good to excellent interobserver reliability (intraclass correlation coefficients, 0.691-0.941). In terms of validity, bone attenuation of the L1 to L4, femoral neck, and greater trochanter on CT showed significant correlations with BMD of each area on DEXA (correlation coefficients, 0.399-0.613). Bone attenuation of the distal tibia and talus on CT showed significant correlations with BMD of all parts on DEXA (correlation coefficients, 0.493-0.581 for distal tibia, 0.396-0.579 for talus). CONCLUSION: Lower extremity CT is a useful screening tool for osteoporosis, and peripheral bone attenuation on lower extremity CT adequately reflects central BMD on DEXA.
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Osteoporose/diagnóstico por imagem , Absorciometria de Fóton/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea , Feminino , Fêmur/diagnóstico por imagem , Fêmur/fisiopatologia , Humanos , Masculino , Programas de Rastreamento/métodos , Pessoa de Meia-Idade , Variações Dependentes do Observador , Osteoporose/fisiopatologia , Reprodutibilidade dos Testes , Estudos Retrospectivos , Tíbia/diagnóstico por imagem , Tíbia/fisiopatologia , Tomografia Computadorizada por Raios X/métodosRESUMO
We investigated the metal-insulator transition (MIT) driven by all-in-all-out (AIAO) antiferromagnetic ordering in the 5d pyrochlore Cd(2)Os(2)O(7) using optical spectroscopy and first-principles calculations. We showed that the temperature evolution in the band-gap edge and free carrier density were consistent with rigid upward (downward) shifts of electron (hole) bands, similar to the case of Lifshitz transitions. The delicate relationship between the band gap and free carrier density provides experimental evidence for the presence of an AIAO metallic phase, a natural consequence of such MITs. The associated spectral weight change at high energy and first-principles calculations further support the origin of the MIT from the band shift near the Fermi level. Our data consistently support that the MIT induced by AIAO ordering in Cd(2)Os(2)O(7) is not close to a Slater type but instead to a Lifshitz type.
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Oxidative stress is involved in the pathophysiology of rheumatoid arthritis (RA). We investigated the therapeutic potential of rebamipide, a gastroprotective agent with a property of reactive oxygen species scavenger, on the development of inflammatory polyarthritis and the pathophysiological mechanisms by which rebamipide might confer anti-arthritic effects in SKG mice, an animal model of RA. Intraperitoneal (i.p.) injection of rebamipide attenuated the severity of clinical and histological arthritis. Rebampide treatment reduced the number of T helper type 1 (Th1), Th2, Th17, inducible T cell co-stimulator (ICOS)(+) follicular helper T (Tfh) transitional type (T2) and mature B cells in the spleen, but increased the number of regulatory T (Treg ), CD19(+) CD1d(high) CD5(high) , CD19(+) CD25(high) forkhead box protein 3 (FoxP3)(+) regulatory B (Breg ) cells, memory B cells, and transitional type 1 (T1) B cells. In addition, flow cytometric analysis revealed significantly decreased populations of FAS(+) GL-7(+) germinal centre B cells and B220(-) CD138(+) plasma cells in the spleens of rebamipide-treated SKG mice compared to controls. Rebamipide decreased germinal centre B cells and reciprocally induced Breg cells in a dose-dependent manner in vitro. Rebamipide-induced Breg cells had more suppressive capacity in relation to T cell proliferation and also inhibited Th17 differentiation from murine CD4(+) T cells. Together, these data show that i.p. administration of rebamipide suppresses arthritis severity by inducing Breg and Treg cells and suppressing Tfh and Th17 cells in a murine model of RA.
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Alanina/análogos & derivados , Artrite Experimental/tratamento farmacológico , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/imunologia , Doenças Autoimunes/tratamento farmacológico , Doenças Autoimunes/imunologia , Linfócitos B/efeitos dos fármacos , Quinolonas/farmacologia , Alanina/imunologia , Alanina/farmacologia , Animais , Formação de Anticorpos/efeitos dos fármacos , Formação de Anticorpos/imunologia , Artrite Experimental/imunologia , Linfócitos B/imunologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/imunologia , Proliferação de Células/efeitos dos fármacos , Centro Germinativo/efeitos dos fármacos , Centro Germinativo/imunologia , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Quinolonas/imunologia , Baço/efeitos dos fármacos , Baço/imunologia , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Células Th17/efeitos dos fármacos , Células Th17/imunologiaRESUMO
We report on the infrared studies of the interlayer charge dynamics of a prototypical pnictide superconductor Ba(Fe(0.926)Co(0.074))(2)As(2). We succeeded in probing the intrinsic interlayer response by performing infrared experiments on the crystals with a cleaved ac surface. Our experiments identify the coexistence of the suppression of the electronic spectral weight and the development of a coherent Drude-like response in the normal state. The formation of the interlayer condensate is clearly observed in the superconducting state and appears to be linked to coherent contribution to the normal-state conductivity.
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The temperature (T) dependence of the optical conductivity spectra σ(ω) of a single crystal SrRuO(3) thin film is studied over a T range from 5 to 450 K. We observed significant T dependence of the spectral weights of the charge transfer and interband d-d transitions across the ferromagnetic Curie temperature (T(c) â¼ 150 K). Such T dependence was attributed to the increase in the Ru spin moment, which is consistent with the results of density functional theory calculations. T scans of σ(Ω,T) at fixed frequencies Ω reveal a clear T(2) dependence below T(c), demonstrating that the Stoner mechanism is involved in the evolution of the electronic structure. In addition, σ(Ω,T) continues to evolve at temperatures above T(c), indicating that the local spin moment persists in the paramagnetic state. This suggests that SrRuO(3) is an intriguing oxide system with itinerant ferromagnetism.
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Posterior reversible encephalopathy syndrome (PRES) is an uncommon neurologic condition associated with systemic lupus erythematosus (SLE). This study aimed to demonstrate the risk factors and clinical outcome of PRES in patients with SLE. Fifteen patients with SLE were diagnosed with PRES by characteristic clinical manifestations and magnetic resonance imaging (MRI) features from 2000 to 2012. Clinical profiles and outcomes were assessed for this study population. Additionally, 48 SLE patients with neurologic symptoms who underwent brain MRI were included for comparative analyses. The median age and duration of SLE in patients with PRES was 27 and 6.1 years, respectively. Comparison between patients with and without PRES revealed significant differences in the presentation of hypertension and seizure, lupus nephritis with renal insufficiency, treatment with high-dose steroid and cyclophosphamide, recent transfusion, and lupus activity measured by SLE disease activity index. Renal failure was the single independent factor with a high odds ratio of 129.250 by multivariate analysis. Of 15 patients, four experienced relapse and two died of sepsis during hospitalization. Our results suggest that lupus nephritis with renal dysfunction and other related clinical conditions can precede the occurrence of PRES in patients with SLE. It is important to perform early brain imaging for a timely diagnosis of PRES when clinically suspected.
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Lúpus Eritematoso Sistêmico/complicações , Síndrome da Leucoencefalopatia Posterior/etiologia , Insuficiência Renal/fisiopatologia , Adolescente , Adulto , Ciclofosfamida/uso terapêutico , Feminino , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Hospitalização , Humanos , Imunossupressores/uso terapêutico , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Lúpus Eritematoso Sistêmico/fisiopatologia , Nefrite Lúpica/fisiopatologia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Análise Multivariada , Síndrome da Leucoencefalopatia Posterior/fisiopatologia , Recidiva , Insuficiência Renal/etiologia , República da Coreia , Estudos Retrospectivos , Fatores de Risco , Adulto JovemRESUMO
Renal relapse in patients with lupus nephritis (LN) is a risk factor for poor renal function. Therefore, there is a need to identify clinical and serological risk factors for renal relapse. A total of 108 patients with LN were enrolled in this study. All the subjects had achieved complete remission or partial remission following six months of induction therapy. We retrospectively analyzed their clinical and laboratory indices, final renal function, and kidney biopsy findings. The median follow-up period after LN diagnosis was 81 months. Renal relapse had occurred in 36 patients; it occurred in 38% and 46% of patients within five and 10 years after achievement of renal remission, respectively. There was no difference between the relapsed rate in patients with complete remission and that in those with partial remission. Clinical variables at LN onset and renal biopsy findings in the patients with sustained remission and relapsed patients were also not different. The probability of renal relapse was significantly higher in patients with an earlier age of onset of systemic lupus erythematosus (SLE) (≤ 28 years versus >28 years; HR 7.308, P=0.001), seronegativity for anti-Ro antibody (seronegativity versus seropositivity; HR 3.514, P=0.007), and seropositivity for anti-dsDNA antibody at six months after initiation of induction therapy (HR 8.269, P=0.001). Our study demonstrated that early onset of SLE, seronegativity for anti-Ro antibody and increased anti-dsDNA antibody following six months of induction therapy independently predict renal relapse among the LN patients.
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Nefrite Lúpica/tratamento farmacológico , Nefrite Lúpica/epidemiologia , Adulto , Biópsia , Ciclofosfamida/uso terapêutico , Feminino , Humanos , Imunossupressores/uso terapêutico , Rim/patologia , Testes de Função Renal , Nefrite Lúpica/patologia , Masculino , Valor Preditivo dos Testes , Recidiva , Indução de Remissão , República da Coreia/epidemiologia , Estudos Retrospectivos , Adulto JovemRESUMO
Laser sintering of metal nanoparticles is a key technology for high-performance printed electronics fabricated on heat-sensitive substrates such as glass or plastic. Although laser-sintered electronic devices have been successfully fabricated, the role of the induced temperature field in the laser sintering process has not been reported thus far. In this work, the effect of temperature on the laser sintering process is described for the first time using a two-dimensional transient heat conduction equation for inkjet-printed silver nanoparticle ink. The in situ electrical resistance was measured to estimate the transient thermal conductivity and hence the temperature of the sintered ink during the laser sintering process. To verify the estimated laser sintering temperature, the morphology of furnace-sintered silver nanoparticle ink was compared with that of laser-sintered ink. The electrical characteristics and surface morphology of laser-sintered ink are found to be related to the process temperature.
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OBJECTIVE: The objectives were to investigate the in vivo effects of treatment with rebamipide on pain severity and cartilage degeneration in an experimental model of rat osteoarthritis (OA) and to explore its mode of action. MATERIALS AND METHODS: OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA). Oral administration of rebamipide was initiated on the day of MIA injection, 3 or 7 days after. Limb nociception was assessed by measuring the paw withdrawal latency and threshold. We analyzed the samples macroscopically and histomorphologically, and used immunohistochemistry to investigate the expression of matrix metalloproteinase-13 (MMP-13), interleukin-1ß (IL-1ß), hypoxia-inducible factor-2α (HIF-2α), inducible nitric oxide synthase (iNOS), and nitrotyrosine in knee joints. Real-time quantitative reverse transcription-polymerase chain reaction was used to quantify the mRNA for catabolic and anticatabolic factors in human OA chondrocytes. RESULTS: Rebamipide showed an antinociceptive property and attenuated cartilage degeneration. Rebamipide reduced the expression of MMP-13, IL-1ß, HIF-2α, iNOS, and nitrotyrosine in OA cartilage in a dose-dependent manner. Nitrotyrosine expression in the subchondral bone region was decreased in the rebamipide-treated joints. mRNA expression of MMP-1, -3, and -13, and ADAMTS5 was attenuated in IL-1ß-stimulated human OA chondrocytes. By contrast, rebamipide induced the mRNA expression of tissue inhibitor of metalloproteinase-1 and -3. CONCLUSION: The results show the inhibitory effects of rebamipide on pain production and cartilage degeneration in experimentally induced OA. The suppression of oxidative damage and the restoration of extracellular matrix homeostasis of articular chondrocyte suggest that rebamipide is a potential therapeutic strategy for OA.
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Alanina/análogos & derivados , Analgésicos/farmacologia , Artrite Experimental/tratamento farmacológico , Cartilagem Articular/efeitos dos fármacos , Condrócitos/efeitos dos fármacos , Osteoartrite/tratamento farmacológico , Dor/tratamento farmacológico , Quinolonas/farmacologia , Alanina/farmacologia , Animais , Artrite Experimental/patologia , Artrite Experimental/fisiopatologia , Biomarcadores/metabolismo , Cartilagem Articular/patologia , Células Cultivadas , Condrócitos/metabolismo , Condrócitos/patologia , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Metaloproteinases da Matriz Secretadas/genética , Metaloproteinases da Matriz Secretadas/metabolismo , Camundongos , Osteoartrite/complicações , Osteoartrite/patologia , Estresse Oxidativo/efeitos dos fármacos , Dor/complicações , Dor/fisiopatologia , Medição da Dor , Ratos , Ratos Wistar , Índice de Gravidade de Doença , Joelho de Quadrúpedes/efeitos dos fármacos , Joelho de Quadrúpedes/patologiaRESUMO
We report an infrared optical study of the pnictide high-temperature superconductor BaFe(1.84)Co(0.16)As(2) and its parent compound BaFe(2)As(2). We demonstrate that electronic correlations are moderately strong and do not change across the spin-density wave transition or with doping. By examining the energy scale and direction of spectral weight transfer, we argue that Hund's coupling J is the primary mechanism that gives rise to correlations.
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We report on infrared studies of charge dynamics in a prototypical pnictide system: the BaFe2As2 family. Our experiments have identified hallmarks of the pseudogap state in the BaFe2As2 system that mirror the spectroscopic manifestations of the pseudogap in the cuprates. The magnitude of the infrared pseudogap is in accord with that of the spin-density-wave gap of the parent compound. By monitoring the superconducting gap of both P- and Co-doped compounds, we find that the infrared pseudogap is unrelated to superconductivity. The appearance of the pseudogap is found to correlate with the evolution of the antiferromagnetic fluctuations associated with the spin-density-wave instability. The strong-coupling analysis of infrared data further reveals the interdependence between the magnetism and the pseudogap in the iron pnictides.
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We investigated the doping and temperature evolutions of the optical response of Sr3(Ir1-xMnx)2O7 single crystals with 0 ≤ x ≤ 0.36 by utilizing infrared spectroscopy. Substitution of 3d transition metal Mn ions into Sr3Ir2O7 is expected to induce an insulator-to-metal transition via the decrease in the magnitude of the spin-orbit coupling and the hole doping. In sharp contrast, our data reveal the resilience of the spin-orbit coupling and the incoherent character of the charge transport. Upon Mn substitution, an incoherent in-gap excitation at about 0.25 eV appeared with the decrease in the strength of the optical transitions between the effective total angular momentum Jeff bands of the Ir ions. The resonance energies of the optical transitions between the Jeff bands which are directly proportional to the magnitude of the spin-orbit coupling hardly varied. In addition to these evolutions of the low-energy response, Mn substitution led to the emergence of a distinct high-energy optical excitation at about 1.2 eV which is larger than the resonance energies of the optical transitions between the Jeff bands. This observation indicates that the Mn 3d states are located away from the Ir 5d states in energy and that the large difference in the on-site energies of the transition metal ions is responsible for the incoherent charge transport and the robustness of the spin-orbit coupling. The effect of Mn substitution was also registered in the temperature dependence of the electronic response. The anomaly in the optical response of the parent compound observed at the antiferromagnetic transition temperature is notably suppressed in the Mn-doped compounds despite the persistence of the long-range antiferromagnetic ordering. The suppression of the spin-charge coupling could be related to charge disproportionation of the Ir ions.