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1.
Nature ; 620(7974): 525-532, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37587297

RESUMEN

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.

2.
Phys Rev Lett ; 129(14): 147001, 2022 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-36240422

RESUMEN

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.

3.
Eur J Anaesthesiol ; 37(3): 196-202, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31977627

RESUMEN

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.


Asunto(s)
Retraso en el Despertar Posanestésico , Bloqueo Neuromuscular , Fármacos Neuromusculares no Despolarizantes , Adolescente , Adulto , Anciano , Inhibidores de la Colinesterasa/efectos adversos , Retraso en el Despertar Posanestésico/inducido químicamente , Retraso en el Despertar Posanestésico/diagnóstico , Retraso en el Despertar Posanestésico/epidemiología , Humanos , Persona de Mediana Edad , Neostigmina/efectos adversos , Bloqueo Neuromuscular/efectos adversos , Nervios Periféricos , República de Corea , Sugammadex , Adulto Joven
4.
Anesth Analg ; 126(4): 1349-1352, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-28991119

RESUMEN

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.


Asunto(s)
Anestesia Raquidea/métodos , Anestesiólogos , Salud Laboral , Mesas de Operaciones , Postura , Adolescente , Adulto , Anciano , Anestesia Raquidea/instrumentación , Diseño de Equipo , Ergonomía , Femenino , Humanos , Inyecciones Espinales , Masculino , Persona de Mediana Edad , Agujas , Posicionamiento del Paciente , Estudios Prospectivos , República de Corea , Método Simple Ciego , Adulto Joven
5.
Muscle Nerve ; 56(3): 510-518, 2017 09.
Artículo en Inglés | MEDLINE | ID: mdl-27977864

RESUMEN

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.


Asunto(s)
Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Desarrollo de Músculos/efectos de los fármacos , Mioblastos/efectos de los fármacos , N-Metilaspartato/toxicidad , Animales , Diferenciación Celular/fisiología , Línea Celular , Proliferación Celular/fisiología , Ratones , Desarrollo de Músculos/fisiología , Mioblastos/metabolismo , Especies Reactivas de Oxígeno/antagonistas & inhibidores , Especies Reactivas de Oxígeno/metabolismo
7.
Sci Adv ; 10(38): eadp2809, 2024 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-39292769

RESUMEN

Biologically inspired artificial vision research has led to innovative robotic vision systems with low optical aberration, wide field of view, and compact form factor. However, challenges persist in object detection and recognition against complex backgrounds and varied lighting. Inspired by the feline eye, which features a vertically elongated pupil and tapetum lucidum, this study introduces an artificial vision system designed for superior object detection and recognition in a monocular framework. Using a slit-like elliptical aperture and a patterned metal reflector beneath a hemispherical silicon photodiode array, the system reduces excessive light and enhances photosensitivity. This design achieves clear focus under bright light and enhanced sensitivity in dim conditions. Theoretical and experimental analyses demonstrate the system's ability to filter redundant information and detect camouflaged objects in diverse lighting, representing a substantial advancement in monocular camera technology and the potential of biomimicry in optical innovations.

8.
Nat Commun ; 15(1): 6021, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-39019856

RESUMEN

The bioinspired camera, comprising a single lens and a curved image sensor-a photodiode array on a curved surface-, was born of flexible electronics. Its economical build lends itself well to space-constrained machine vision applications. The curved sensor, much akin to the retina, helps image focusing, but the curvature also creates a problem of image distortion, which can undermine machine vision tasks such as object recognition. Here we report an anti-distortion single-lens camera, where 4096 silicon photodiodes arrayed on a curved surface in a nonuniform pattern assimilated to the distorting optics are the key to anti-distortion engineering. That is, the photo-pixel distribution pattern itself is warped in the same manner as images are warped, which correctively reverses distortion. Acquired images feature no appreciable distortion across a 120° horizontal view, as confirmed by their neural-network recognition accuracies. This distortion correction via photo-pixel array reconfiguration is a form of in-sensor computing.

9.
J Environ Biol ; 33(5): 969-75, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23734467

RESUMEN

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.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Phaeophyceae/crecimiento & desarrollo , Algas Marinas/crecimiento & desarrollo , Biomasa , Hojas de la Planta/crecimiento & desarrollo , Análisis de Regresión , República de Corea
10.
Chem Commun (Camb) ; (3): 310-2, 2009 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-19209312

RESUMEN

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.

11.
Angew Chem Int Ed Engl ; 48(17): 3096-8, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19309024

RESUMEN

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.

12.
Sci Rep ; 9(1): 18728, 2019 12 10.
Artículo en Inglés | MEDLINE | ID: mdl-31822745

RESUMEN

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.


Asunto(s)
Toma de Decisiones/fisiología , Dolor/psicología , Trastornos de la Articulación Temporomandibular/psicología , Adolescente , Estudios de Casos y Controles , Dolor Facial/patología , Femenino , Humanos , Luxaciones Articulares/patología , Imagen por Resonancia Magnética , Masculino , Trastornos Psicóticos/patología , Articulación Temporomandibular/patología , Trastornos de la Articulación Temporomandibular/patología , Adulto Joven
13.
Blood Coagul Fibrinolysis ; 29(5): 446-450, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29846277

RESUMEN

: 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.


Asunto(s)
Pruebas de Coagulación Sanguínea/métodos , Coagulación Sanguínea/efectos de los fármacos , Femenino , Gluconatos/efectos adversos , Humanos , Cloruro de Magnesio/efectos adversos , Masculino , Cloruro de Potasio/efectos adversos , Acetato de Sodio/efectos adversos , Cloruro de Sodio/efectos adversos , Tromboelastografía , Voluntarios
14.
Biol Pharm Bull ; 25(11): 1446-50, 2002 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-12419957

RESUMEN

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.


Asunto(s)
Glicósidos/farmacología , Células HL-60/efectos de los fármacos , Lactonas/farmacología , Sesquiterpenos/farmacología , Taraxacum , Animales , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Glicósidos/química , Glicósidos/aislamiento & purificación , Células HL-60/citología , Humanos , Lactonas/química , Lactonas/aislamiento & purificación , Ratones , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Estructuras de las Plantas/química , Sesquiterpenos/química , Sesquiterpenos/aislamiento & purificación , Taraxacum/química , Células Tumorales Cultivadas/citología , Células Tumorales Cultivadas/efectos de los fármacos
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