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1.
Nature ; 620(7974): 525-532, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37587297

RESUMO

Interactions among electrons create novel many-body quantum phases of matter with wavefunctions that reflect electronic correlation effects, broken symmetries and collective excitations. Many quantum phases have been discovered in magic-angle twisted bilayer graphene (MATBG), including correlated insulating1, unconventional superconducting2-5 and magnetic topological6-9 phases. The lack of microscopic information10,11 of possible broken symmetries has hampered our understanding of these phases12-17. Here we use high-resolution scanning tunnelling microscopy to study the wavefunctions of the correlated phases in MATBG. The squares of the wavefunctions of gapped phases, including those of the correlated insulating, pseudogap and superconducting phases, show distinct broken-symmetry patterns with a √3 × âˆš3 super-periodicity on the graphene atomic lattice that has a complex spatial dependence on the moiré scale. We introduce a symmetry-based analysis using a set of complex-valued local order parameters, which show intricate textures that distinguish the various correlated phases. We compare the observed quantum textures of the correlated insulators at fillings of ±2 electrons per moiré unit cell to those expected for proposed theoretical ground states. In typical MATBG devices, these textures closely match those of the proposed incommensurate Kekulé spiral order15, whereas in ultralow-strain samples, our data have local symmetries like those of a time-reversal symmetric intervalley coherent phase12. Moreover, the superconducting state of MATBG shows strong signatures of intervalley coherence, only distinguishable from those of the insulator with our phase-sensitive measurements.

3.
Phys Rev Lett ; 129(14): 147001, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36240422

RESUMO

A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a "cascade" of spontaneous symmetry-breaking transitions, sparking interest in the potential relationship between symmetry breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking. Here, we show how atomically resolved scanning tunneling microscopy can be used as a fingerprint of symmetry-breaking order. By analyzing the pattern of sublattice polarization and "Kekulé" distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the "Kramers intervalley coherent state," which theoretical work predicts to be the ground state at even integer fillings, shows a Kekulé distortion which emerges only in a magnetic field.

4.
Eur J Anaesthesiol ; 37(3): 196-202, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31977627

RESUMO

BACKGROUND: Incomplete recovery of neuromuscular blockade is a common postoperative adverse event in the postanaesthesia care unit. OBJECTIVE: We examined and compared the incidence of residual neuromuscular blockade when the recommended dose of neostigmine or sugammadex was administered according to a qualitative nerve stimulator response. DESIGN: A randomised controlled trial. SETTING: A tertiary care hospital in South Korea from September 2017 to November 2017. PATIENTS: Eighty patients aged between 18 and 69 years were included in this study. All were patients scheduled to undergo elective laparoscopic cholecystectomy and who had an American Society of Anaesthesiologists physical status of one or two were eligible. INTERVENTIONS: Patients were allocated randomly to receive neostigmine or sugammadex at the end of surgery. The doses of the reversal agents were based on the response to peripheral nerve stimulation, which was discontinued after administration of the reversal agent. MAIN OUTCOME MEASURES: The primary outcome was the incidence of postoperative residual neuromuscular blockade. The secondary outcomes were the incidences of symptoms or signs of residual neuromuscular blockade such as hypoxaemia, inability to maintain head-lift for 5 s and diplopia. RESULTS: The incidence of residual neuromuscular blockade on arrival in the recovery room was 44.4% in the neostigmine group and 0% in the sugammadex group (P < 0.0001, relative risk = 1.80, 95% confidence interval 1.36 to 2.41). The incidences of adverse events in the recovery room were low and comparable between the groups. CONCLUSION: The incidence of residual neuromuscular blockade on arrival in the recovery room was significantly higher in the neostigmine group than that in the sugammadex group. However, the incidence of adverse events was similar in the neostigmine and sugammadex groups. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03292965.


Assuntos
Recuperação Demorada da Anestesia , Bloqueio Neuromuscular , Fármacos Neuromusculares não Despolarizantes , Adolescente , Adulto , Idoso , Inibidores da Colinesterase/efeitos adversos , Recuperação Demorada da Anestesia/induzido quimicamente , Recuperação Demorada da Anestesia/diagnóstico , Recuperação Demorada da Anestesia/epidemiologia , Humanos , Pessoa de Meia-Idade , Neostigmina/efeitos adversos , Bloqueio Neuromuscular/efeitos adversos , Nervos Periféricos , República da Coreia , Sugammadex , Adulto Jovem
5.
Sci Rep ; 9(1): 18728, 2019 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-31822745

RESUMO

We evaluated the clinical, magnetic resonance imaging (MRI), and psychological characteristics of adolescents with temporomandibular disorder (TMD) and compared facial macrotrauma effects between young and older adolescents. This case-control study included 70 randomly selected patients (35 young adolescents aged 12-16 years and 35 older adolescents aged 17-19 years) who had been diagnosed with TMD. Each age group was further subdivided according to the presence (T1) or absence (T0) of a macrotrauma history. All patients completed questionnaires on temporomandibular joint (TMJ) pain and dysfunction. We analyzed TMD severity symptoms using TMD-related indexes and the physical changes of TMJ using TMJ MR images. The Symptom Checklist-90-Revised was used to evaluate the patients' psychological status. Anterior disc displacement was the most frequently observed MRI finding, occurring in a significant proportion of young (47 joints, 67.1%) and older adolescents (40 joints, 57.1%). The prevalence of all the MRI findings (disc displacement, disc deformity, condylar degeneration, and effusion) did not differ between the T0 and T1 subgroups among young and older adolescents. Conversely, the psychological factors differed significantly between the subgroups. Among young adolescents, the mean scores of somatization, obsessive-compulsiveness, hostility, phobic ideation, and psychosis were significantly higher in the T1 subgroup than in the T0 subgroup (all p < 0.05). Furthermore, these increased psychological scores positively correlated with TMD indexes. Clinicians should consider that a weakened psychological status could be an aggravating factor in young adolescents with TMD and should consider the implications in future assessment of such patients.


Assuntos
Tomada de Decisões/fisiologia , Dor/psicologia , Transtornos da Articulação Temporomandibular/psicologia , Adolescente , Estudos de Casos e Controles , Dor Facial/patologia , Feminino , Humanos , Luxações Articulares/patologia , Imageamento por Ressonância Magnética , Masculino , Transtornos Psicóticos/patologia , Articulação Temporomandibular/patologia , Transtornos da Articulação Temporomandibular/patologia , Adulto Jovem
6.
Blood Coagul Fibrinolysis ; 29(5): 446-450, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29846277

RESUMO

: The current study aimed to measure the effects of Plasma-Lyte 148 solution on the blood coagulation profile according to the hemodilution level using rotational thromboelastometry (ROTEM) tests. Venous blood was collected from 12 healthy volunteers and divided into four specimen bottles, which were diluted at different levels with Plasma-Lyte 148 (0, 20, 40, and 60%). Following this, ROTEM tests were performed on the study samples. We found that as the hemodilution level increased, the ROTEM values showed a hypocoagulable pattern. The change rate of the maximum clot firmness (MCF) of INTEM was greater in the 40 (P = 0.015) and 60% (P < 0.001) dilutions than it was in the 20% dilution. Greater lengthening of the clot formation time of EXTEM was observed in the 60% dilution than it was in the 20% dilution (P < 0.001). The alpha-angle of EXTEM showed a greater decrease in the 60% dilution than it did in the 20% dilution (P < 0.001). A larger change rate of the MCF of EXTEM was observed in the 40 (P = 0.003) and 60% (P < 0.001) dilutions than it was in the 20% dilution. A greater decrease in the MCF of FIBTEM was identified in the 40 (P = 0.009) and 60% (P < 0.001) dilutions than in the 20% dilution. All coagulation pathways exhibited hypocoagulable patterns as the hemodilution level increased. However, most of the mean values of ROTEM parameters were within the normal reference range, except for those of the 60% dilution.


Assuntos
Testes de Coagulação Sanguínea/métodos , Coagulação Sanguínea/efeitos dos fármacos , Feminino , Gluconatos/efeitos adversos , Humanos , Cloreto de Magnésio/efeitos adversos , Masculino , Cloreto de Potássio/efeitos adversos , Acetato de Sódio/efeitos adversos , Cloreto de Sódio/efeitos adversos , Tromboelastografia , Voluntários
7.
Anesth Analg ; 126(4): 1349-1352, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28991119

RESUMO

The aim of this study was to find the optimal table height to facilitate insertion of the spinal needle at a 90° angle and to reduce the anesthesiologist's discomfort. Sixty patients were randomly allocated according to landmarks on the anesthesiologist's body: umbilicus (group U), lowest rib margin (R), xiphoid process (X), and nipple (N). The coronal insertion angle between the patient's skin and the spinal needle was obtuse in groups U and R, and 90° in group X. We demonstrated that high operating tables at the xiphoid and nipple level facilitate more optimal needle entry angles while reducing the discomfort and joint flexion of anesthesiologists during spinal anesthesia.


Assuntos
Raquianestesia/métodos , Anestesiologistas , Saúde Ocupacional , Mesas Cirúrgicas , Postura , Adolescente , Adulto , Idoso , Raquianestesia/instrumentação , Desenho de Equipamento , Ergonomia , Feminino , Humanos , Injeções Espinhais , Masculino , Pessoa de Meia-Idade , Agulhas , Posicionamento do Paciente , Estudos Prospectivos , República da Coreia , Método Simples-Cego , Adulto Jovem
8.
Muscle Nerve ; 56(3): 510-518, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-27977864

RESUMO

INTRODUCTION: N-methyl-d-aspartate (NMDA) is expressed in sensory neurons and plays important roles in peripheral pain mechanisms. The aim of this study was to examine the effects and molecular mechanisms of NMDA on C2C12 myoblast proliferation and differentiation. METHODS: Cytotoxicity and differentiation were examined by the MTT assay, reverse transcription-polymerase chain reaction, and immunofluorescence. RESULTS: NMDA had no cytotoxicity (10-500 µM) and inhibited myoblastic differentiation of C2C12 cells, as assessed by F-actin immunofluorescence and levels of mRNAs encoding myogenic markers such as myogenin and myosin heavy-chain 2. It inhibited phosphorylation of mammalian target of rapamycin (mTOR) by inactivating mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. It induced reactive oxygen species production. Furthermore, NMDA-suppressed expression of F-actin was reversed by adding the antioxidant N-acetylcysteine. CONCLUSIONS: Collectively, these results indicate that NMDA impairs myogenesis or myogenic differentiation in C2C12 cells through the mTOR/MAPK signaling pathways and may lead to skeletal muscle degeneration. Muscle Nerve 56: 510-518, 2017.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Desenvolvimento Muscular/efeitos dos fármacos , Mioblastos/efeitos dos fármacos , N-Metilaspartato/toxicidade , Animais , Diferenciação Celular/fisiologia , Linhagem Celular , Proliferação de Células/fisiologia , Camundongos , Desenvolvimento Muscular/fisiologia , Mioblastos/metabolismo , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo
9.
J Environ Biol ; 33(5): 969-75, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23734467

RESUMO

We installed seaweed reef for restoration of barron ground coast. We hollowed out a U-shaped groove in a cross-shaped artificial seaweed reef and covered it with a zinc sheet (U-bar) to transplant Ecklonia cava growing on Dellenia wood by hand, installing the U-bar on the artificial seaweed reef, fixing it with concrete. Thus seaweed can be attached easily, with pre-installed stainless bolts and nuts. The length of Ecklonia cava leaf transplanted to the cross-shaped reef was 7.2 cm in February 2005 reached its maximum size, 35.9 cm (n = 30) by July. Thereafter, it decreased to 18.9 cm in October due to shedding. The leaf weight after the experiment was 24.8 from the initial 0.4 cm (n = 30). Regression analysis showed Y = 0.7875X-4.6488 (R2 = 0.7225) for blade length and Y = 0.0025X2.6733 (R2 = 0.8711) for leaf weight. The high values of the R2 values for the two measurements were highly reliable, with the reliability of the linear regression function higher than that of the functions of 2 variables. The artificial seaweed forest constructed in the barren ground was highly comparable with natural seaweed forest in terms of growth, indicating that the artificial seaweed construction can be done in an easy, efficient and economically viable way. This further indicates that the technology developed by the present study can be extensively used for the project for artificial seaweed forest construction.


Assuntos
Recuperação e Remediação Ambiental/métodos , Phaeophyceae/crescimento & desenvolvimento , Alga Marinha/crescimento & desenvolvimento , Biomassa , Folhas de Planta/crescimento & desenvolvimento , Análise de Regressão , República da Coreia
10.
Angew Chem Int Ed Engl ; 48(17): 3096-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19309024

RESUMO

The growth and self-organization of organic crystals between a source (S) and drain (D) electrode by a method based on the use of a micropipette and isothermal evaporation of the solvent in a two-liquid system led to the formation of organic-crystal transistors (see polarized optical micrograph). The method is similar to ink-jet printing and should be suitable for the fabrication of low-cost and mass-producible printed electronic devices.

11.
Chem Commun (Camb) ; (3): 310-2, 2009 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-19209312

RESUMO

The self-assembly of molecules in a gel by strong pi-pi stacking interactions between the thienylvinylene anthracene backbones and van der Waals interactions between the long alkyl chains has generated nanofibers; from the organogels, organic single-nanofiber transistors were successfully embodied.

12.
Biol Pharm Bull ; 25(11): 1446-50, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12419957

RESUMO

The present work was performed to elucidate the active moiety of a sesquiterpene lactone, taraxinic acid-1'-O-beta-D-glucopyranoside (1). from Taraxacum coreanum NAKAI on the cytotoxicity of various cancer cells. Based on enzymatic hydrolysis and MTT assay, the active moiety should be attributed to the aglycone taraxinic acid (1a). rather than the glycoside (1). Taraxinic acid exhibited potent antiproliferative activity against human leukemia-derived HL-60. In addition, this compound was found to be a potent inducer of HL-60 cell differentiation as assessed by a nitroblue tetrazolium reduction test, esterase activity assay, phagocytic activity assay, morphology change, and expression of CD 14 and CD 66 b surface antigens. These results suggest that taraxinic acid induces the differentiation of human leukemia cells to monocyte/macrophage lineage. Moreover, the expression level of c-myc was down-regulated during taraxinic acid-dependent HL-60 cell differentiation, whereas p21(CIP1) and p27(KIP1) were up-regulated. Taken together, our results suggest that taraxinic acid may have potential as a therapeutic agent in human leukemia.


Assuntos
Glicosídeos/farmacologia , Células HL-60/efeitos dos fármacos , Lactonas/farmacologia , Sesquiterpenos/farmacologia , Taraxacum , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Glicosídeos/química , Glicosídeos/isolamento & purificação , Células HL-60/citologia , Humanos , Lactonas/química , Lactonas/isolamento & purificação , Camundongos , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Estruturas Vegetais/química , Sesquiterpenos/química , Sesquiterpenos/isolamento & purificação , Taraxacum/química , Células Tumorais Cultivadas/citologia , Células Tumorais Cultivadas/efeitos dos fármacos
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