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1.
Nanotechnology ; 32(14): 145709, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33326944

RESUMO

The microstructural evolutions in self-catalyzed GaAs nanowires (NWs) were investigated by using in situ heating transmission electron microscopy (TEM). The morphological changes of the self-catalyst metal gallium (Ga) droplet, the GaAs NWs, and the atomic behavior at the interface between the self-catalyst metal gallium and GaAs NWs were carefully studied by analysis of high-resolution TEM images. The microstructural change of the Ga-droplet/GaAs-NWs started at a low temperature of ∼200 °C. Formation and destruction of atomic layers were observed at the Ga/GaAs interface and slow depletion of the Ga droplet was detected in the temperature range investigated. Above 300 °C, the evolution process dramatically changed with time: The Ga droplet depleted rapidly and fast growth of zinc-blende (ZB) GaAs structures were observed in the droplet. The Ga droplet was completely removed with time and temperature. When the temperature reached ∼600 °C, the decomposition of GaAs was detected. This process began in the wurtzite (WZ) structure and propagated to the ZB structure. The morphological and atomistic behaviors in self-catalyzed GaAs NWs were demonstrated based on thermodynamic considerations, in addition to the effect of the incident electron beam in TEM. Finally, GaAs decomposition was demonstrated in terms of congruent vaporization.

2.
Langmuir ; 36(39): 11538-11545, 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-32921056

RESUMO

Oxygen (O2)-mediated controlled radical polymerization was performed on surfaces under ambient conditions, enabling on-surface polymer brush growth under open-to-air conditions at room temperature in the absence of metal components. Polymerization of zwitterionic monomers using this O2-mediated surface-initiated reversible addition fragmentation chain-transfer (O2-SI-RAFT) method yielded hydrophilic surfaces that exhibited anti-biofouling effects. O2-SI-RAFT polymerization can be performed on large surfaces under open-to-air conditions. Various monomers including (meth)acrylates and acrylamides were employed for O2-SI-RAFT polymerization; the method is thus versatile in terms of the polymers used for coating and functionalization. A wide range of hydrophilic and hydrophobic monomers can be employed. In addition, the end-group functionality of the polymer grown by O2-SI-RAFT polymerization allowed chain extension to form block copolymer brushes on a surface.

3.
Am J Geriatr Psychiatry ; 28(12): 1308-1316, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33023798

RESUMO

OBJECTIVE: This study aimed to investigate the different clinical characteristics among elderly coronavirus disease 2019 (COVID-19) patients with and without mental disorders in South Korea and determine if these characteristics have an association with underlying mental disorders causing mortality. METHOD: A population-based comparative cohort study was conducted using the national claims database. Individuals aged ≥65 years with confirmed COVID-19 between January 1, 2020 and April 10, 2020 were assessed. The endpoints for evaluating mortality for all participants were death, 21 days after diagnosis, or April 10, 2020. The risk of mortality associated with mental disorders was estimated using Cox hazards regression. RESULTS: We identified 814 elderly COVID-19 patients (255 [31.3%] with mental disorder and 559 [68.7%] with nonmental disorder). Individuals with mental disorders were found more likely to be older, taking antithrombotic agents, and had diabetes, hypertension, chronic obstructive lung disease, and urinary tract infections than those without mental disorders. After propensity score stratification, our study included 781 patients in each group (236 [30.2%] with mental disorder and 545 [69.8%] with nonmental disorder). The mental disorder group showed higher mortality rates than the nonmental disorder group (12.7% [30/236] versus 6.8% [37/545]). However, compared to patients without mental disorders, the hazard ratio (HR) for mortality in elderly COVID-19 patients with mental disorders was not statistically significant (HR: 1.57, 95%CI: 0.95-2.56). CONCLUSION: Although the association between mental disorders in elderly individuals and mortality in COVID-19 is unclear, this study suggests that elderly patients with comorbid conditions and those taking psychiatric medications might be at a higher risk of COVID-19.


Assuntos
Infecções por Coronavirus , Transtornos Mentais , Pandemias , Pneumonia Viral , Idoso , Betacoronavirus , COVID-19 , Estudos de Coortes , Comorbidade , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/mortalidade , Feminino , Humanos , Masculino , Transtornos Mentais/epidemiologia , Transtornos Mentais/virologia , Saúde Mental/estatística & dados numéricos , Pneumonia Viral/diagnóstico , Pneumonia Viral/mortalidade , Modelos de Riscos Proporcionais , República da Coreia/epidemiologia , Medição de Risco , Fatores de Risco , SARS-CoV-2
4.
Nanotechnology ; 31(4): 045302, 2020 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-31578000

RESUMO

Targeted irradiation of nanostructures by a finely focused ion beam provides routes to improved control of material modification and understanding of the physics of interactions between ion beams and nanomaterials. Here, we studied radiation damage in crystalline diamond and silicon nanostructures using a focused helium ion beam, with the former exhibiting extremely long-range ion propagation and large plastic deformation in a process visibly analogous to blow forming. We report the dependence of damage morphology on material, geometry, and irradiation conditions (ion dose, ion energy, ion species, and location). We anticipate that our method and findings will not only improve the understanding of radiation damage in isolated nanostructures, but will also support the design of new engineering materials and devices for current and future applications in nanotechnology.

5.
Small ; 14(23): e1801023, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29717811

RESUMO

Shape memory alloys (SMAs) are widely utilized as an actuation source in microscale devices, since they have a simple actuation mechanism and high-power density. However, they have limitations in terms of strain range and actuation speed. High-speed microscale SMA actuators are developed having diamond-shaped frame structures with a diameter of 25 µm. These structures allow for a large elongation range compared with bulk SMA materials, with the aid of spring-like behavior under tensile deformation. These actuators are validated in terms of their applicability as an artificial muscle in microscale by investigating their behavior under mechanical deformation and changes in thermal conditions. The shape memory effect is triggered by delivering thermal energy with a laser. The fast heating and cooling phenomenon caused by the scale effect allows high-speed actuation up to 1600 Hz. It is expected that the proposed actuators will contribute to the development of soft robots and biomedical devices.

6.
Nanotechnology ; 28(43): 435205, 2017 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-28850552

RESUMO

Here, we optimized ultrathin films of granular NbN on SiO2 and of amorphous αW5Si3. We showed that hybrid superconducting nanowire single-photon detectors (SNSPDs) made of 2 nm thick αW5Si3 films over 2 nm thick NbN films exhibit advantageous coexistence of timing (<5 ns reset time and 52 ps timing jitter) and efficiency (>96% quantum efficiency) performance. We discuss the governing mechanism of this hybridization via the proximity effect. Our results demonstrate saturated SNSPDs performance at 1550 nm optical wavelength and suggest that such hybridization can significantly expand the range of available superconducting properties, impacting other nano-superconducting technologies. Lastly, this hybridization may be used to tune properties, such as the amorphous character of superconducting films.

7.
Eur Arch Otorhinolaryngol ; 272(3): 727-36, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24691851

RESUMO

The objective of this study was to investigate the efficacy of early management of post-thyroidectomy unilateral vocal cord palsy (UVCP) and the clinical utility of the thyroidectomy-related voice questionnaire (TVQ) when planning UVCP treatment. The study group comprised 48 consecutive patients diagnosed with UVCP after thyroidectomy. Laryngoscopic examination and voice analysis were conducted, and the TVQ was administered pre-thyroidectomy and at 2 weeks and 1, 3, 6, and 12 months post-thyroidectomy. Twenty-five patients with aspiration symptoms and severe vocal difficulties received injection laryngoplasty, and 23 with no aspiration symptoms and relatively mild vocal difficulties underwent voice therapy. We performed a video fluoroscopic swallowing study on each patient 2 weeks after thyroidectomy and 1 month following the procedure. The average total TVQ scores 2 weeks post-thyroidectomy were 51.92 ± 11.42 in the injection laryngoplasty group and 35.78 ± 12.99 in the voice therapy group. Both subjective and objective parameters improved significantly at 1 month after treatment and continued to improve slowly over the next 12 months (p < 0.01) in both groups. TVQ scores were significantly lower in the injection laryngoplasty group than in the voice therapy group 1 month post-intervention (p < 0.01). At the study end point, the greatest improvement in subjective symptoms occurred in temporary VCP patients who underwent injection laryngoplasty. The optimal TVQ score cut-off distinguishing the two groups was 45 (68.0 % sensitivity, 78.3 % specificity). In conclusion, early management following timely diagnosis of post-thyroidectomy UVCP can improve symptoms within 1 month. Moreover, application of TVQ will aid clinicians to plan treatment for postoperative VCP patients.


Assuntos
Tomada de Decisões , Inquéritos e Questionários , Tireoidectomia/efeitos adversos , Paralisia das Pregas Vocais/etiologia , Paralisia das Pregas Vocais/terapia , Adulto , Idoso , Feminino , Humanos , Laringoplastia , Laringoscopia , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Treinamento da Voz , Adulto Jovem
8.
Eur Arch Otorhinolaryngol ; 271(6): 1685-91, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23949547

RESUMO

(18)F-FDG PET/CT is clinically useful in the initial staging and follow-up of patients with head and neck squamous cell carcinoma (HNSCC). We studied the potential prognostic significance of preoperative (18)F-FDG PET/CT in HNSCC. The medical records of 294 patients who underwent preoperative (18)F-FDG PET/CT for HNSCC were retrospectively reviewed. The median SUVmax of the primary lesions (SUVmax-p) and cervical lymph nodes (SUVmax-n) was 7.98 ± 5.04 (range 1.2-28.7) and 3.34 ± 3.70 (range 1.0-20.4), respectively. There was a significant difference between with and without recurrence in SUVmax-p (11.14 ± 5.36 vs. 6.78 ± 4.35, p < 0.001) and SUVmax-n (5.60 ± 4.22 vs. 1.75 ± 1.46, p < 0.001). The cut-off values of SUVmax-p and SUVmax-n in the context of recurrence and cancer-related death were 8.5 and 3.5. The 5-year disease-free survival of patients with SUVmax-p < 8.5 and SUVmax-n < 3.5 was 79 and 79%, respectively, whereas that of patients with SUVmax-p ≥ 8.5 and SUVmax-n ≥ 3.5 was 39 and 30 %, respectively. Multivariate analysis confirmed the significant association between 5-year disease-free survival and SUVmax-p ≥ 8.5 (hazard ratio (HR) 2.68, p < 0.001) and SUVmax-n ≥ 3.5 (HR 2.29, p = 0.007). Furthermore, SUVmax-p ≥ 8.5 (HR 3.20, p = 0.012) and SUVmax-n ≥ 3.5 (HR 2.14, p < 0.001) were associated with 5-year overall survival. (18)F-FDG PET/CT cut-off values of SUVmax-p ≥ 8.5 or SUVmax-n ≥ 3.5 are associated with a recurrence and survival in HNSCC.


Assuntos
Carcinoma de Células Escamosas/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias Laríngeas/diagnóstico por imagem , Linfonodos/diagnóstico por imagem , Neoplasias Bucais/diagnóstico por imagem , Neoplasias Faríngeas/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Escamosas/cirurgia , Estudos de Coortes , Intervalo Livre de Doença , Feminino , Fluordesoxiglucose F18 , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Neoplasias Laríngeas/cirurgia , Masculino , Pessoa de Meia-Idade , Neoplasias Bucais/cirurgia , Imagem Multimodal , Análise Multivariada , Pescoço , Neoplasias Faríngeas/cirurgia , Tomografia por Emissão de Pósitrons , Prognóstico , Modelos de Riscos Proporcionais , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Carcinoma de Células Escamosas de Cabeça e Pescoço , Tomografia Computadorizada por Raios X , Adulto Jovem
9.
Clin Anat ; 27(3): 360-4, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23893612

RESUMO

The purpose of this study was to establish normative data of laryngotracheal dimensions and shape and to evaluate differences associated with age and sex using three-dimensional (3D) imaging. A total of 120 patients (64 boys and 56 girls) were included. Subjects were divided into four groups: Group 1 (0-2 years), Group 2 (3-7 years), Group 3 (8-13 years), and Group 4 (14-20 years). Using 3D image processing software, the laryngeal volume (LV), tracheal volume (TV), anteroposterior diameter at the glottis, cross-sectional area (CSA) at the subglottis, and laryngeal angle (LA) of the thyroid laminae were measured. Parameters of laryngotracheal volume and size were positively correlated with age, whereas the LA was inversely correlated with age. The LV, TV, CSA-3 mm, and CSA-5 mm exhibited a growth spurt in Groups 2 and 3. The LA decreased at a faster rate in Group 1 (P = 0.012). In Groups 1 and 2, there were no differences between genders for each laryngotracheal segmentation or plane. However, gender differences in the TV of Group 3 were statistically significant (P = 0.030). In Group 4, gender differences of all airway parameters were evident. Volume and other dimensions of the laryngotracheal airway increase with age. There was a significant increase in the LV, TV, CSA-3 mm, and CSA-5 mm in Groups 2 and 3. The LA correlated negatively with age in the Group 1. Significant sex dimorphisms are evident in Group 4.


Assuntos
Desenvolvimento do Adolescente , Broncoscopia/métodos , Desenvolvimento Infantil , Intubação Intratraqueal/métodos , Laringe/crescimento & desenvolvimento , Traqueia/crescimento & desenvolvimento , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Imageamento Tridimensional , Lactente , Laringe/diagnóstico por imagem , Masculino , Tamanho do Órgão , Tomografia Computadorizada por Raios X , Traqueia/diagnóstico por imagem , Adulto Jovem
10.
Sci Rep ; 14(1): 4633, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38409437

RESUMO

Hydrophobic surfaces have a wide range of applications, such as water harvesting, self-cleaning, and anti-biofouling. However, traditional methods of achieving hydrophobicity often involve the use of toxic materials such as fluoropolymers. This study aims to create controllable wettability surfaces with a three-dimensional geometry using a laser base powder bed fusion (PBF) process with commercially pure titanium (CP-Ti) and silicone oil as non-toxic materials. The optimal PBF process parameters for fabricating micropillar structures, which are critical for obtaining the surface roughness necessary for achieving hydrophobic properties, were investigated experimentally. After fabricating the micropillar structures using PBF, their surface energy was reduced by treatment with silicone oil. Silicone oil provides a low-surface-energy coating that contributes to the water-repellent nature of hydrophobic surfaces. The wettability of the treated CP-Ti surfaces was evaluated based on the diameter of the pillars and the space between them. The structure with the optimal diameter and spacing of micropillars exhibited a high contact angle (156.15°). A pronounced petal effect (sliding angle of 25.9°) was achieved because of the morphology of the pillars, indicating the controllability of wetting. The micropillar diameter, spacing, and silicone oil played crucial roles in determining the water contact and sliding angle, which are key metrics for surface wettability.

11.
Acta Otolaryngol ; 143(5): 429-433, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37148316

RESUMO

BACKGROUND: Patients with cartilage invasion in hypopharyngeal squamous cell carcinoma (HPSCC) would benefit from partial laryngopharyngectomy (PLP). AIMS/OBJECTIVES: The purpose of this study was to examine the treatment outcomes of PLP for HPSCC with cartilage invasion, with a focus on the oncological safety and the function preservation. MATERIALS AND METHODS: We performed a retrospective review of 28 patients with HPSCC with thyroid or cricoid cartilage invasion who had undergone upfront surgery and were followed for more than one year between 1993 and 2019. RESULTS: Twelve patients treated with PLP (42.9%) and 16 patients treated with total laryngopharyngectomy (TLP) for cartilage invasion in HPSCC were identified. There was no significant difference in recurrence between the PLP group (7/12, 58.3%) and the TLP group (8/16, 50.0%) (p = .718). PLP was not associated with decreased five-year disease free survival (p = .662) or disease specific survival (p = .883) rates compared to TLP. Nine patients receiving PLP could be decannulated and retained intelligible speech (9/12, 75%). Gastrostomy tubes were placed in the PLP group (5/12, 42.9%) and TLP group (1/16, 6.2%) (p = .057). CONCLUSIONS AND SIGNIFICANCE: PLP appears to be a feasible option for the treatment of thyroid or cricoid cartilage invasion in HPSCC.


Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Neoplasias Hipofaríngeas , Humanos , Glândula Tireoide/patologia , Cartilagem Cricoide/cirurgia , Carcinoma de Células Escamosas de Cabeça e Pescoço/cirurgia , Laringectomia , Estudos Retrospectivos , Neoplasias de Cabeça e Pescoço/cirurgia
12.
Biol Pharm Bull ; 35(9): 1440-6, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22975493

RESUMO

Apigenin (5,7,4'-trihydroxyflavone) is a principal ingredient of Cirsium japonicum. These experiments were performed to determine whether apigenin has neuroprotective effects against kainic acid (KA)-induced excitotoxicity in vitro and in vivo. Intraperitoneal (i.p.) administration of apigenin (25, 50 mg/kg) decreased the seizure scores induced by KA injection (40 mg/kg, i.p.) in mice. In addition, the convulsion onset time was significantly delayed by apigenin administration. Moreover, we found that apigenin blocked KA-induced seizure-form electroencephalogram (EEG) discharge activity in the brain cortex. In hippocampal cells, apigenin inhibited KA-induced excitotoxicity in a dose-dependent manner as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To study the possible mechanisms underlying the in vitro neuroprotective effects of apigenin against KA-induced cytotoxicity, we also examined the effect of apigenin on intracellular reactive oxygen species (ROS) elevations in cultured hippocampal neurons and found that apigenin treatment dose-dependently inhibited intracellular ROS elevation. The remarkable reduction of glutathione (GSH) levels induced by KA in hippocampal tissues was reversed by apigenin in a dose-dependent manner. In addition, similar results were obtained after pretreatment with free radical scavengers such as trolox and dimethylthiourea (DMTU). Finally, after confirming the protective effect of apigenin in hippocampal CA3 region, we found apigenin is an active compound in KA-induced neuroprotection. These results collectively indicate that apigenin alleviates KA-induced excitotoxicity by quenching ROS as well as inhibiting GSH depletion in hippocampal neurons.


Assuntos
Antioxidantes/uso terapêutico , Apigenina/uso terapêutico , Carduus/química , Hipocampo/efeitos dos fármacos , Fitoterapia , Extratos Vegetais/uso terapêutico , Convulsões/prevenção & controle , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Apigenina/farmacologia , Relação Dose-Resposta a Droga , Eletroencefalografia/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/efeitos adversos , Glutationa/metabolismo , Hipocampo/metabolismo , Ácido Caínico , Masculino , Camundongos , Camundongos Endogâmicos ICR , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Convulsões/induzido quimicamente , Convulsões/metabolismo
13.
Polymers (Basel) ; 14(12)2022 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-35745949

RESUMO

Polydimethylsiloxane (PDMS) is widely utilised as a substrate for wearable (stretchable) electronics where high fatigue resistance is required. Cyclic loadings cause the rearrangement of the basic molecular structure of polymer chains, which leads to changes in the mechanical properties of the PDMS structure. Accordingly, it is necessary to investigate reliable mechanical properties of PDMS considering both monotonic and cyclic loading conditions. This study aims to present the mechanical properties of PDMS films against both monotonic and cyclic loading. The effects of certain parameters, such as film thickness and magnitude of tensile strain, on mechanical properties are also investigated. The test results show that PDMS films have a constant monotonic elastic modulus regardless of the influence of thickness and tensile loading, whereas a cyclic elastic modulus changes depending on experimental parameters. Several material parameters, such as neo-Hookean, Mooney-Rivlin, the third-order Ogden model, and Yeoh, are defined to mimic the stress-strain behaviours of the PDMS films. Among them, it is confirmed that the third-order Ogden model is best suited for simulating the PDMS films over the entire tensile test range. This research makes contributions not only to understanding the mechanical behaviour of the PDMS films between the monotonic and the cycle loadings, but also through providing trustworthy hyperelastic material coefficients that enable the evaluation of the structural integrity of the PDMS films using the finite element technique.

14.
ACS Appl Mater Interfaces ; 14(48): 53999-54011, 2022 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-36444765

RESUMO

It has been challenging to synthesize p-type SnOx (1 < x < 2) and engineer the electrical properties such as carrier density and mobility due to the narrow processing window and the localized oxygen 2p orbitals near the valence band. Herein, we report on the multifunctional encapsulation of p-SnOx to limit the surface adsorption of oxygen and selectively permeate hydrogen into the p-SnOx channel for thin-film transistor (TFT) applications. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements identified that ultrathin SiO2 as a multifunctional encapsulation layer effectively suppressed the oxygen adsorption on the back channel surface of p-SnOx and selectively diffused hydrogen across the entire thickness of the channel. Encapsulated p-SnOx-based TFTs demonstrated much enhanced channel conductance modulation in response to the gate bias applied, featuring higher on-state current and lower off-state current (on/off ratio > 103), field effect mobility of 3.41 cm2/(V s), and threshold voltages of ∼5-10 V. The fabricated devices show minimal deviations as small as ±6% in the TFT performance parameters, which demonstrates good reproducibility of the fabrication process. The relevance between the TFT performance and the effects of hydrogen permeation is discussed in regard to the intrinsic and extrinsic doping mechanisms. Density functional theory calculations reveal that hydrogen-related impurity complexes are in charge of the enhanced channel conductance with gate biases, which further supports the selective permeation of hydrogen through a thin SiO2 encapsulation.

15.
J Cardiovasc Pharmacol ; 58(4): 446-9, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21975870

RESUMO

In a previous experiment, (-)-epigallocatechin-3-O-gallate (EGCG) reduced caffeine-induced locomotor activity and stereotyped behaviors and inhibited caffeine-induced neuronal stimulant activity. This research was performed to give additional evidence that EGCG counteracts caffeine-induced stimulant effects in animals. EGCG inhibited caffeine-induced cardiovascular activation measures, such as arterial pressure and heart rate. In addition, the increases in the levels of adrenaline and noradrenaline in the blood induced by caffeine was reduced by EGCG. We suggest that EGCG may reduce caffeine-induced increases in blood pressure and heart rate and may decrease the levels of catecholamines in the blood. Therefore, EGCG counteracts caffeine-induced cardiovascular activity. The stimulant effects of caffeine should be reduced by the amount of EGCG in green tea.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Cafeína/farmacologia , Catequina/análogos & derivados , Frequência Cardíaca/efeitos dos fármacos , Animais , Catequina/farmacologia , Epinefrina/sangue , Masculino , Norepinefrina/sangue , Ratos , Ratos Wistar
16.
J Nanosci Nanotechnol ; 11(1): 189-94, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21446425

RESUMO

The feasibility of new InSbTe (IST) chalcogenide materials at the deposition temperatures of 225 and 250 degrees C using metalorganic chemical vapor deposition (MOCVD) for phase-change random access memory (PRAM) applications was investigated. Samples grown at 225 degrees C consisted of the main InTe phase, including a small amount of Sb. On the other hand, samples grown at 250 degrees C included the crystalline phases of InSb and InSbTe. MOCVD-IST materials are powerful candidates for highly-integrated PRAM applications.

17.
Nanomaterials (Basel) ; 11(12)2021 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-34947728

RESUMO

Efficient water electrolysis is one of the key issues in realizing a clean and renewable energy society based on hydrogen fuel. However, several obstacles remain to be solved for electrochemical water splitting catalysts, which are the high cost of noble metals and the high overpotential of alternative catalysts. Herein, we suggest Ni-based alternative catalysts that have comparable performances with precious metal-based catalysts and could be applied to both cathode and anode by precise phase control of the pristine catalyst. A facile microwave-assisted procedure was used for NiO nanoparticles anchored on reduced graphene oxide (NiO NPs/rGO) with uniform size distribution in ~1.8 nm. Subsequently, the Ni-NiO dual phase of the NPs (A-NiO NPs/rGO) could be obtained via tailored partial reduction of the NiO NPs/rGO. Moreover, we demonstrate from systematic HADDF-EDS and XPS analyses that metallic Ni could be formed in a local area of the NiO NP after the reductive annealing procedure. Indeed, the synergistic catalytic performance of the Ni-NiO phase of the A-NiO NPs/rGO promoted hydrogen evolution reaction activity with an overpotential as 201 mV at 10 mA cm-2, whereas the NiO NPs/rGO showed 353 mV. Meanwhile, the NiO NPs/rGO exhibited the most excellent oxygen evolution reaction performance among all of the Ni-based catalysts, with an overpotential of 369 mV at 10 mA cm-2, indicating that they could be selectively utilized in the overall water splitting. Furthermore, both catalysts retained their activities over 12 h with constant voltage and 1000 cycles under cyclic redox reaction, proving their high durability. Finally, the full cell capability for the overall water electrolysis system was confirmed by observing the generation of hydrogen and oxygen on the surface of the cathode and anode.

18.
Ultramicroscopy ; 226: 113304, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33964613

RESUMO

The use of electron mirrors in aberration correction and surface-sensitive microscopy techniques such as low-energy electron microscopy has been established. However, in this work, by implementing an easy to construct, fully electrostatic electron mirror system under a sample in a conventional scanning electron microscope (SEM), we present a new imaging scheme which allows us to form scanned images of the top and bottom surfaces of the sample simultaneously. We believe that this imaging scheme could be of great value to the field of in-situ SEM which has been limited to observation of dynamic changes such as crack propagation and other surface phenomena on one side of samples at a time. We analyze the image properties when using a flat versus a concave electron mirror system and discuss two different regimes of operation. In addition to in-situ SEM, we foresee that our imaging scheme could open up avenues towards spherical aberration correction by the use of electron mirrors in SEMs without the need for complex beam separators.

19.
RSC Adv ; 11(45): 28342-28346, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35480747

RESUMO

Amorphous cobalt-calcium phosphate composite (CCPC) films are electrochemically prepared on various electrodes by utilizing the solid phase of hydroxyapatite as a phosphate source. The CCPC film formation is surface process in which the dissolution of hydroxyapatite and the deposition of CCPC film concurrently occur on the electrode surface without the mass transfer of phosphate ions into the bulk solution. Elemental, crystallographic, and morphological analyses (EDX, ICP-AES, XPS, and XRD) indicate that the CCPC is composed of amorphous cobalt oxide with calcium and phosphate. The film exhibits durable oxygen evolution reaction (OER) catalytic properties under neutral and basic aqueous condition. Compared to using solution phase of phosphate source, our preparation method utilizing solid hydroxyapatite has advantage of preventing unnecessary chemical reaction between phosphate and other chemical species in bulk solution.

20.
ACS Appl Mater Interfaces ; 13(46): 55676-55686, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34779629

RESUMO

The fabrication of oxide-based p-n heterojunctions that exhibit high rectification performance has been difficult to realize using standard manufacturing techniques that feature mild vacuum requirements, low thermal budget processing, and scalability. Critical bottlenecks in the fabrication of these heterojunctions include the narrow processing window of p-type oxides and the charge-blocking performance across the metallurgical junction required for achieving low reverse current and hence high rectification behavior. The overarching goal of the present study is to demonstrate a simple processing route to fabricate oxide-based p-n heterojunctions that demonstrate high on/off rectification behavior, a low saturation current, and a small turn-on voltage. For this study, room-temperature sputter-deposited p-SnOx and n-InGaZnO (IGZO) films were chosen. SnOx is a promising p-type oxide material due to its monocationic system that limits complexities related to processing and properties, compared to other multicationic oxide materials. For the n-type oxide, IGZO is selected due to the knowledge that postprocessing annealing critically reduces the defect and trap densities in IGZO to ensure minimal interfacial recombination and high charge-blocking performance in the heterojunctions. The resulting oxide p-n heterojunction exhibits a high rectification ratio greater than 103 at ±3 V, a low saturation current of ∼2 × 10-10 A, and a small turn-on voltage of ∼0.5 V. In addition, the demonstrated oxide p-n heterojunctions exhibit excellent stability over time in air due to the p-SnOx with completed reaction annealing in air and the reduced trap density in n-IGZO.

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