Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
1.
Nat Mater ; 21(2): 165-172, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34737454

RESUMO

Despite the importance of glass forming ability as a major alloy characteristic, it is poorly understood and its quantification has been experimentally laborious and computationally challenging. Here, we uncover that the glass forming ability of an alloy is represented in its amorphous structure far away from equilibrium, which can be exposed by conventional X-ray diffraction. Specifically, we fabricated roughly 5,700 alloys from 12 alloy systems and characterized the full-width at half-maximum, Δq, of the first diffraction peak in the X-ray diffraction pattern. A strong correlation between high glass forming ability and a large Δq was found. This correlation indicates that a large dispersion of structural units comprising the amorphous structure is the universal indicator for high metallic glass formation. When paired with combinatorial synthesis, the correlation enhances throughput by up to 100 times compared to today's state-of-the-art combinatorial methods and will facilitate the discovery of bulk metallic glasses.


Assuntos
Ligas , Vidro , Ligas/química , Vidro/química , Difração de Raios X
2.
Nano Lett ; 12(2): 964-9, 2012 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-22224857

RESUMO

In this article, we present the transport and magnetotransport of high-quality graphene transistors on conventional SiO(2)/Si substrates by modification with organic molecule octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs). Graphene devices on OTS SAM-functionalized substrates with high carrier mobility, low intrinsic doping, suppressed carrier scattering, and reduced thermal activation of resistivity at room temperature were observed. Most interestingly, the remarkable magnetotransport of graphene devices with pronounced quantum Hall effect, strong Shubnikov-de Haas oscillations, a nonzero Berry's phase, and a short carrier scattering time also confirms the high quality of graphene on this ultrasmooth organic SAM-modified platform. The high-performance graphene transistors on the solution-processable OTS SAM-functionalized SiO(2)/Si substrates are promising for the future development of large-area and low-cost fabrications of graphene-based nanoelectronics.


Assuntos
Grafite/química , Magnetismo , Silanos/química , Transistores Eletrônicos , Membranas Artificiais , Tamanho da Partícula , Silício/química , Propriedades de Superfície , Titânio/química
3.
Ear Nose Throat J ; : 1455613211036770, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34490795

RESUMO

OBJECTIVE: Accidental pharyngeal fishbone ingestion is a common complaint in ear, nose, and throat clinics. Approximately two-thirds of the accidentally ingested fishbones can be removed using tongue depressors and indirect laryngoscopy. However, the remaining third is challenging to identify and remove using these methods. These difficult fishbones require identification and removal via more advanced approaches. Video-guided laryngoscope is used to deal with difficult fishbones in our center. This study aimed to explore the risk factors for difficult fishbones. METHODS: A prospective study was performed at a teaching hospital on 2080 patients. Univariate and multivariate analyses were performed to identify the risk factors. RESULTS: The common fishbone locations were the tonsils (39.8%; defined as STEP-I), tongue base (37.1%), vallecula (13.3%; STEP-II), and hypopharynx (9.8%; STEP-III). With increasing STEP level, the ratio of difficult fishbones correspondingly increased (Z = 13.919, P < .001), and the proportions were 21.1%, 41.9%, and 70% in STEP-I, II, and III, respectively. In particular, fishbones in STEP-III (vs STEP-I) had a higher risk of difficult fishbones (odds ratio [OR]: 11.573, 95% CI: 7.987-16.769). Complaints of neck pain (yes vs no), foreign body sensation (yes vs no), and shorter length of fishbones always had a lower risk of difficult fishbones (OR: 0.455, 95% CI: 0.367-0.564; OR: 0.284, 95% CI: 0.191-0.422; OR: 0.727, 95% CI: 0.622-0.85). Missing teeth (yes vs no), swallowing behavior after fishbone ingestion (yes vs no), and male patients (vs female) had a higher risk of difficult fishbones (OR: 1.9, 95% CI: 1.47-2.456; OR: 1.631, 95% CI: 1.293-2.059; OR: 1.278, 95% CI: 1.047-1.56). CONCLUSIONS: Neck pain, foreign body sensation, fishbone length, patient age and sex, tooth status, and swallowing behavior after fishbone ingestion are independent risk factors for difficult fishbones.

4.
ACS Appl Mater Interfaces ; 12(17): 19840-19854, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32270675

RESUMO

Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au1)-UCNP-gold (Au2)] capable of exhibiting lasing at ultralow thresholds under CW excitation are demonstrated. The metastable energy-level characteristics of lanthanides are advantageous for creating population inversion. In particular, localized surface plasmon resonance-based electromagnetic hotspots in the nanocomposites and the huge enhancement of scattering coefficient for the formation of coherent closed loops due to multiple scattering facilitate the process of stimulated emissions as confirmed by theoretical simulations. The nanocomposites are subjected to stretchable systems for enhancing the lasing action (threshold ∼ 0.06 kW cm-2) via a light-trapping effect. The applications in bioimaging of HeLa cells and antibacterial activity (photothermal therapy) are demonstrated using the newly designed Au1-UCNP-Au2 nanocomposites.


Assuntos
Antibacterianos/farmacologia , Nanopartículas Metálicas/química , Nanocompostos/química , Antibacterianos/química , Antibacterianos/efeitos da radiação , Dimetilpolisiloxanos/química , Érbio/química , Érbio/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Fluoretos/química , Fluoretos/efeitos da radiação , Ouro/química , Ouro/efeitos da radiação , Grafite/química , Células HeLa , Humanos , Hipertermia Induzida/métodos , Lasers , Nanopartículas Metálicas/efeitos da radiação , Testes de Sensibilidade Microbiana , Nanocompostos/efeitos da radiação , Staphylococcus aureus/efeitos dos fármacos , Ressonância de Plasmônio de Superfície , Itérbio/química , Itérbio/efeitos da radiação , Ítrio/química , Ítrio/efeitos da radiação
5.
Biol Reprod ; 71(3): 740-8, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15115722

RESUMO

The present study was designed to investigate subcellular localization of MAD2 in rat oocytes during meiotic maturation and its relationship with kinetochores, chromosomes, and microtubules. Oocytes at germinal vesicle (GV), prometaphase I (ProM-I), metaphase I (M-I), anaphase I (A-I), telophase I (T-I), and metaphase II (M-II) were fixed and immunostained for MAD2, kinetochores, microtubules and chromosomes. The stained oocytes were examined by confocal microscopy. Some oocytes from GV to M-II stages were treated by a microtubule disassembly drug, nocodazole, or treated by a microtubule stabilizer, Taxol, before examination. Anti-MAD2 antibody was also injected into the oocytes at GV stage and the injected oocytes were cultured for 6 h for examination of chromosome alignment and spindle formation. It was found that MAD2 was at the kinetochores in the oocytes at GV and ProM-I stages. Once the oocytes reached M-I stage in which an intact spindle was formed and all chromosomes were aligned at the equator of the spindle, MAD2 disappeared. However, when oocytes from GV to M-II stages were treated by nocodazole, spindles were destroyed and MAD2 was observed in all treated oocytes. When nocodazole-treated oocytes at M-I and M-II stages were washed and cultured for spindle recovery, it was found that, once the relationship between microtubules and chromosomes was established, MAD2 disappeared in the oocytes even though some chromosomes were not aligned at the equator of the spindle. On the other hand, when oocytes were treated with Taxol, MAD2 localization was not changed and was the same as that in the control. However, immunoblotting of MAD2 indicated that MAD2 was present in the oocytes at all stages; nocodazole and Taxol treatment did not influence the quantity of MAD2 in the cytoplasm. Significantly higher proportions of anti-MAD2 antibody-injected oocytes proceeded to premature A-I stage and more oocytes had misaligned chromosomes in the spindles. The present study indicates that MAD2 is a spindle checkpoint protein in rat oocytes during meiosis. When the spindle was destroyed by nocodazole, MAD2 was reactivated in the oocytes to overlook the attachment between chromosomes and microtubules. However, in this case, MAD2 could not check unaligned chromosomes in the recovered spindles, suggesting that a normal chromosome alignment is maintained only in the oocytes without any microtubule damages during maturation.


Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Cinetocoros/metabolismo , Meiose/fisiologia , Microtúbulos/metabolismo , Oócitos/metabolismo , Animais , Anticorpos/farmacologia , Antineoplásicos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Proteínas de Ligação ao Cálcio/imunologia , Proteínas de Ciclo Celular , Células Cultivadas , Cromossomos de Mamíferos/metabolismo , Feminino , Proteínas Mad2 , Nocodazol/farmacologia , Oócitos/citologia , Oócitos/efeitos dos fármacos , Paclitaxel/farmacologia , Polímeros , Ratos , Ratos Sprague-Dawley , Proteínas Repressoras , Fuso Acromático/metabolismo , Tubulina (Proteína)/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA