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2.
Diagnostics (Basel) ; 14(7)2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38611629

RESUMO

The classification of nasolabial folds into three types, each with distinct causative factors and mechanisms, is explored. Age-related changes in facial skin and connective tissues are examined in detail, revealing variations across different facial regions due to variances in tissue firmness and thickness. The innovative 'Reverse Technique,' involving cog threads to enhance tissue traction and effectiveness in thread-lifting procedures, is introduced. Detailed technical guidelines, anatomical considerations, and safety measures are provided, emphasizing the importance of identifying optimal vectors and fixing points to achieve maximum lifting effects while minimizing potential risks, particularly those associated with vascular structures. Additionally, the 'Cross Technique using volumizing thread' is discussed, designed to smooth tissue boundaries and rejuvenate sagging areas. Facial anatomy, including the positioning of arteries and ligaments, is underscored as essential for ensuring the safety and efficacy of procedures. In conclusion, this review stands as a comprehensive guide for practitioners, offering insights into innovative thread-lifting methods and their applications in addressing nasolabial folds. The primary focus is on achieving optimal aesthetic results while prioritizing patient safety.

3.
J Funct Morphol Kinesiol ; 9(2)2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38651425

RESUMO

This study aimed to determine the effectiveness of radial extracorporeal shockwave therapy (rESWT) in enhancing ankle function in patients with Achilles tendon injuries. The choice of rESWT was based on previous success in the treatment of musculoskeletal conditions. The study involved an intervention group that received rESWT, and a control group that received sham therapy. The results revealed that rESWT led to significant improvements in single-leg vertical jump (d = 0.55, p < 0.05), indicating enhanced power generation and ankle functionality that were not observed in the control group. Additionally, the therapy resulted in increased ankle mobility, as observed by improvements in plantar flexion and heel-rise tests. Interestingly, these functional gains were not accompanied by changes in the Achilles tendon stiffness, suggesting that the benefits of rESWT may be more functional than structural. This study highlights rESWT as a promising tool for rehabilitation, particularly following Achilles tendon injuries. The study concluded that, although rESWT appears to improve certain aspects of ankle function, further studies with a larger and more diverse population over a longer period are necessary to confirm these findings and establish comprehensive treatment protocols.

4.
J Cosmet Dermatol ; 23(3): 830-838, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37877460

RESUMO

OBJECTIVES: Biological aspect and clinical research demonstrated that dual-frequency ultrasound (local dynamic micro-massage, LDM) waves of very high frequency can significantly modify cellular signaling providing anti-inflammatory and anti-fibrotic effects. During the recent past, these waves were successfully applied for the treatment of various inflammatory skin conditions, hypertrophic scars, and chronical wounds. Since the main complications after rhinoseptoplasty are caused by excessive inflammatory reactions and development of fibrosis along nasal implants which can lead to a revision rhinoseptoplasty, in this retrospective multicenter blinded study we have evaluated the efficacy of LDM ultrasound for the treatment of the postoperative perilesional ecchymosis and edema in patients after rhinoseptoplasty. METHODS: Twenty-four patients received daily LDM treatment (study group) for 5 days starting from the first day postoperative, whereas 24 patients (control group) were treated with conventional ice packs. Dynamic reduction of the postoperative perilesional ecchymosis and edema was followed up, and the total duration of these side effects was determined within specific paranasal anatomical areas. RESULTS: Post-rhinoseptoplasty ecchymosis and edema were observed in the areas of anterior cheek, lower eyelids, and upper eyelids. Duration of the postoperative perilesional edema was significantly reduced in the group treated with LDM (1.9 ± 0.9 days) compared with control group (4.5 ± 2.1 days). Duration of the ecchymosis was also significantly reduced in LDM group (2.8 ± 1.4 days) compared with controls (7.4 ± 2.8 days). Postoperative patient satisfaction in LDM-treated and control groups was 3.1 ± 1.3 and 1.5 ± 0.7, respectively, demonstrating significantly higher satisfaction in LDM-treated group. CONCLUSIONS: This study proved that the post-rhinoseptoplasty group treated with LDM ultrasound showed a significantly shorter duration of the postsurgical perilesional ecchymosis and edema, with no substantial adverse effects other than those observed in the control group. It can be suggested that ultrasound treatment can serve as an alternative option for the noninvasive management of postoperative perilesional ecchymosis and edema.


Assuntos
Equimose , Rinoplastia , Humanos , Equimose/etiologia , Equimose/terapia , Edema/terapia , Edema/tratamento farmacológico , Nariz/cirurgia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/tratamento farmacológico , Rinoplastia/métodos
5.
Medicina (Kaunas) ; 59(12)2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38138280

RESUMO

Background and Objectives: Abdominal muscle exercises with limb movements are more effective for trunk stabilization than traditional exercises involving trunk flexion alone. This study examined the effects of abdominal exercises incorporating sprinter pattern and crunch exercises on changes in the lordotic curve and abdominal muscle activation in individuals with low back pain caused by hyperlordosis resulting from weak abdominal muscles. Materials and Methods: In this single-blind, randomized controlled trial, a total of 40 participants with hyperlordosis were recruited and randomly assigned to perform either sprinter-pattern abdominal exercises or crunch exercises. The participants assigned to each group performed three sets of ten abdominal exercises. The lumbar lordotic angle (LLA) and sacrohorizontal angle (SHA) were assessed prior to and following the intervention, whereas abdominal muscle activity was gauged throughout the intervention period. Changes in the LLA and SHA were measured by radiography. Abdominal muscle activity was measured using electromyography. Results: The LLA and SHA decreased significantly in both groups (p < 0.001), while the sprinter-pattern exercise group showed a statistically significant decrease compared to the crunch exercise group (p < 0.001). In the activity of the abdominal muscles, there was no significant difference in the rectus abdominis muscle between the two groups (p > 0.005). However, a significant difference between the external and internal oblique muscles was observed, and the activities of both muscles were significantly higher in the sprinter-pattern exercise group than in the crunch exercise group (p < 0.005). Conclusions: Abdominal exercise using a sprinter pattern may be effective in reducing lumbar lordosis by strengthening the abdominal muscles in patients with hyperlordosis.


Assuntos
Lordose , Humanos , Método Simples-Cego , Músculos Abdominais/fisiologia , Exercício Físico/fisiologia , Reto do Abdome/fisiologia
6.
Int J Mol Sci ; 24(8)2023 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-37108444

RESUMO

This systematic review aimed to synthesize and quantify the results of the studies investigating the changes in fibroblast growth factor-21 (FGF-21) induced by exercise. We searched for studies that did not differentiate between patients and healthy adults but compared them before and after exercise and with and without exercise. For quality assessment, the risk-of-bias assessment tool for nonrandomized studies and the Cochrane risk-of-bias tool were used. A quantitative analysis was performed using the standardized mean difference (SMD) and random-effects model in RevMan 5.4. A total of 94 studies were searched in international electronic databases, and after screening, 10 studies with 376 participants were analyzed. Compared with no exercise, there was a significant increase in the FGF-21 levels from before to after exercise (SMD = 1.05, 95% confidence interval (CI), 0.21 to 1.89). The changes in FGF-21 levels in the exercise group showed a significant difference from the levels in the controls. The results of the random-effects model were as follows: SMD = 1.12; 95% CI, -0.13 to 2.37. While the data on acute exercise were not synthesized in this study, FGF-21 levels generally increased after chronic exercise compared with no exercise.


Assuntos
Terapia por Exercício , Exercício Físico , Adulto , Humanos , Terapia por Exercício/métodos , Fatores de Crescimento de Fibroblastos
7.
Acute Crit Care ; 38(1): 95-103, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36935538

RESUMO

BACKGROUND: In patients with severe trauma, the diagnosis of acute kidney injury (AKI) is important because it is a predictive factor for poor prognosis and can affect patient care. The diagnosis and staging of AKI are based on change in serum creatinine (SCr) levels from baseline. However, baseline creatinine levels in patients with traumatic injuries are often unknown, making the diagnosis of AKI in trauma patients difficult. This study aimed to enhance the accuracy of AKI diagnosis in trauma patients by presenting an appropriate reference creatinine estimate (RCE). METHODS: We reviewed adult patients with severe trauma requiring intensive care unit admission between 2015 and 2019 (n=3,228) at a single regional trauma center in South Korea. AKI was diagnosed based on the current guideline published by the Kidney Disease: Improving Global Outcomes organization. AKI was determined using the following RCEs: estimated SCr75-modification of diet in renal disease (MDRD), trauma MDRD (TMDRD), admission creatinine level, and first-day creatinine nadir. We assessed inclusivity, prognostic ability, and incrementality using the different RCEs. RESULTS: The incidence of AKI varied from 15% to 46% according to the RCE used. The receiver operating characteristic curve of TMDRD used to predict mortality and the need for renal replacement therapy (RRT) had the highest value and was statistically significant (0.797, P<0.001; 0.890, P=0.002, respectively). In addition, the use of TMDRD resulted in a mortality prognostic ability and the need for RRT was incremental with AKI stage. CONCLUSIONS: In this study, TMDRD was feasible as a RCE, resulting in optimal post-traumatic AKI diagnosis and prognosis.

8.
Sensors (Basel) ; 23(3)2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36772108

RESUMO

A vessel sails above the ocean against sea resistance, such as waves, wind, and currents on the ocean surface. Concerning the energy efficiency issue in the marine ecosystem, assigning the right magnitude of shaft power to the propeller system that is needed to move the ship during its operations can be a contributive study. To provide both desired maneuverability and economic factors related to the vessel's functionality, this research studied the shaft power utilization of a factual vessel operational data of a general cargo ship recorded during 16 months of voyage. A machine learning-based prediction model that is developed using Random Forest Regressor achieved a 0.95 coefficient of determination considering the oceanographic factors and additional maneuver settings from the noon report data as the model's predictors. To better understand the learning process of the prediction model, this study specifically implemented the SHapley Additive exPlanations (SHAP) method to disclose the contribution of each predictor to the prediction results. The individualized attributions of each important feature affecting the prediction results are presented.

9.
Medicine (Baltimore) ; 101(35): e30053, 2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36107497

RESUMO

Rotator cuff tear is a common cause of shoulder pain and disability. Arthroscopic rotator cuff repair (ARCR) is performed to treat a torn tendon. Postoperative joint immobilization is essential, but it is a problem that needs to be addressed in the rehabilitation process. This study aimed to evaluate the effects of radial extracorporeal shock wave therapy (rESWT) in patients who underwent ARCR and required active movement after the immobilization period. This study was an open-label, prospective, single-arm trial of 30 inpatients aged >18 years who underwent ARCR. A total of 6 rESWT sessions, along with the conventional rehabilitation program for ARCR patients, were provided at the hospital's sports rehabilitation center for 2 weeks. The application sites of rESWT are periscapular muscles (supraspinatus, infraspinatus, teres minor, and rhomboid). Evaluations were conducted 3 time points-baseline, immediately after the first session of rESWT, and after 2 weeks of intervention. The outcome measures were the numeric pain rating scale for pain, and shoulder flexion, scaption flexion, abduction, horizontal adduction, external rotation, and internal rotation for shoulder range of motion. For shoulder function, disabilities of the arm, shoulder and hand, shoulder pain and disability index, and simple shoulder test were used, and muscle strength was expressed by grip strength. supraspinatus and infraspinatus evaluated thickness, tone, and stiffness. The muscle strength (95% CI, -3.554 to -0.073) and supraspinatus tone (P = .017) showed significant changes immediately after the first session of rESWT. Further, there was significant improvement in ROM (P < .01); shoulder function (P < .01); and muscle strength (95% CI, -3.561 to -0.625), supraspinatus stiffness (95% CI, -67.455 to -26.345), and infraspinatus stiffness (P = .045) after 2 weeks of intervention. However, muscle thickness and tone were significantly improved only in supraspinatus (P = .044, P = .040). Rehabilitation with radial extracorporeal shock wave therapy additionally applied to the periscapular muscles in patients who started active movement in rehabilitation after arthroscopic rotator cuff repair is effective for shoulder function and muscle properties (muscle strength, thickness, tone, and stiffness). However, a randomized controlled trial is needed to further assess the effects of radial extracorporeal shock wave therapy alone.


Assuntos
Tratamento por Ondas de Choque Extracorpóreas , Lesões do Manguito Rotador , Humanos , Estudos Prospectivos , Manguito Rotador/cirurgia , Lesões do Manguito Rotador/cirurgia , Dor de Ombro/etiologia , Dor de Ombro/terapia
10.
Life (Basel) ; 12(8)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36013445

RESUMO

Boron neutron capture therapy (BNCT) is a radiation therapy that selectively kills cancer cells and is being actively researched and developed around the world. In Korea, development of the proton linear accelerator-based BNCT system has completed development, and its anti-cancer effect in the U-87 MG subcutaneous xenograft model has been evaluated. To evaluate the efficacy of BNCT, we measured 10B-enriched boronophenylalanine (BPA) uptake in U-87 MG, FaDu, and SAS cells and evaluated cell viability by clonogenic assays. In addition, the boron concentration in the tumor, blood, and skin on the U-87 MG xenograft model was measured, and the tumor volume was measured for 4 weeks after BNCT. In vitro, the intracellular boron concentration was highest in the order of SAS, FaDu, and U-87 MG, and cell survival fractions decreased depending on the BPA treatment concentration and neutron irradiation dose. In vivo, the tumor volume was significantly decreased in the BNCT group compared to the control group. This study confirmed the anti-cancer effect of BNCT in the U-87 MG subcutaneous xenograft model. It is expected that the proton linear accelerator-based BNCT system developed in Korea will be a new option for radiation therapy for cancer treatment.

11.
Brain Sci ; 12(5)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35624957

RESUMO

The purpose of this study was to quantify the effect of repetitive transcranial magnetic stimulation (rTMS), which is recommended for the improvement of some pain-related symptoms and for antidepressant treatment, on the primary motor cortex (M1) in patients with fibromyalgia (FM). We searched for studies comparing rTMS and sham rTMS in the M1 of FM patients. Pain intensity, quality of life, health status, and depression were compared with or without rTMS for at least 10 sessions. We searched four databases. Quality assessment and quantitative analysis were performed using RevMan 5.4. After screening, five randomized controlled trials of 170 patients with FM were included in the analysis. As a result of the meta-analysis of rTMS on the M1 of individuals with FM, high-frequency rTMS resulted in a significant improvement on quality of life (MD = -2.50; 95% CI: -3.99 to -1.01) compared with sham rTMS. On the other hand, low-frequency rTMS resulted in a significant improvement on health status (MD = 15.02; 95% CI: 5.59 to 24.45). The application of rTMS to the M1 is proposed as an adjunctive measure in the treatment of individuals with FM. Because rTMS has various effects depending on each application site, it is necessary to classify sites or set frequencies as variables.

12.
Adv Mater ; 34(15): e2110454, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35085406

RESUMO

A reliable method for preparing a conformal amorphous carbon (a-C) layer with a thickness of 1-nm-level, is tested as a possible Cu diffusion barrier layer for next-generation ultrahigh-density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4-inch SiO2 /Si wafer substrates with "self-limiting" chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a-C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion "blocking ability" is evaluated by time-dependent dielectric breakdown (TDDB) tests using a metal-oxide-semiconductor (MOS) capacitor structure. A 0.82 nm-thick a-C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm-thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a-C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom-scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.

13.
Sensors (Basel) ; 21(15)2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34372436

RESUMO

In this study, we proposed a data-driven approach to the condition monitoring of the marine engine. Although several unsupervised methods in the maritime industry have existed, the common limitation was the interpretation of the anomaly; they do not explain why the model classifies specific data instances as an anomaly. This study combines explainable AI techniques with anomaly detection algorithm to overcome the limitation above. As an explainable AI method, this study adopts Shapley Additive exPlanations (SHAP), which is theoretically solid and compatible with any kind of machine learning algorithm. SHAP enables us to measure the marginal contribution of each sensor variable to an anomaly. Thus, one can easily specify which sensor is responsible for the specific anomaly. To illustrate our framework, the actual sensor stream obtained from the cargo vessel collected over 10 months was analyzed. In this analysis, we performed hierarchical clustering analysis with transformed SHAP values to interpret and group common anomaly patterns. We showed that anomaly interpretation and segmentation using SHAP value provides more useful interpretation compared to the case without using SHAP value.


Assuntos
Algoritmos , Aprendizado de Máquina , Rios
14.
PLoS One ; 16(3): e0248810, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33755680

RESUMO

BACKGROUND: The effect of alcohol on the outcome and fibrinolysis phenotype in trauma patients remains unclear. Hence, we performed this study to determine whether alcohol is a risk factor for mortality and fibrinolysis shutdown in trauma patients. MATERIALS AND METHODS: A total of 686 patients who presented to our trauma center and underwent rotational thromboelastometry were included in the study. The primary outcome was in-hospital mortality. Logistic regression analysis was performed to determine whether alcohol was an independent risk factor for in-hospital mortality and fibrinolysis shutdown. RESULTS: The rate of in-hospital mortality was 13.8% and blood alcohol was detected in 27.7% of the patients among our study population. The patients in the alcohol-positive group had higher mortality rate, higher clotting time, and lower maximum lysis, more fibrinolysis shutdown, and hyperfibrinolysis than those in the alcohol-negative group. In logistic regression analysis, blood alcohol was independently associated with in-hospital mortality (odds ratio [OR] 2.578; 95% confidence interval [CI], 1.550-4.288) and fibrinolysis shutdown (OR 1.883 [95% CI, 1.286-2.758]). Within the fibrinolysis shutdown group, blood alcohol was an independent predictor of mortality (OR 2.168 [95% CI, 1.030-4.562]). CONCLUSIONS: Alcohol is an independent risk factor for mortality and fibrinolysis shutdown in trauma patients. Further, alcohol is an independent risk factor for mortality among patients who experienced fibrinolysis shutdown.


Assuntos
Intoxicação Alcoólica/complicações , Coagulação Sanguínea , Fibrinólise , Ferimentos e Lesões/sangue , Ferimentos e Lesões/mortalidade , Adulto , Idoso , Etanol/sangue , Feminino , Mortalidade Hospitalar , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Fenótipo
15.
Sensors (Basel) ; 20(24)2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-33353051

RESUMO

This study proposes an unsupervised anomaly detection method using sensor streams from the marine engine to detect the anomalous system behavior, which may be a possible sign of system failure. Previous works on marine engine anomaly detection proposed a clustering-based or statistical control chart-based approach that is unstable according to the choice of hyperparameters, or cannot fit well to the high-dimensional dataset. As a remedy to this limitation, this study adopts an ensemble-based approach to anomaly detection. The idea is to train several anomaly detectors with varying hyperparameters in parallel and then combine its result in the anomaly detection phase. Because the anomaly is detected by the combination of different detectors, it is robust to the choice of hyperparameters without loss of accuracy. To demonstrate our methodology, an actual dataset obtained from a 200,000-ton cargo vessel from a Korean shipping company that uses two-stroke diesel engine is analyzed. As a result, anomalies were successfully detected from the high-dimensional and large-scale dataset. After detecting the anomaly, clustering analysis was conducted to the anomalous observation to examine anomaly patterns. By investigating each cluster's feature distribution, several common patterns of abnormal behavior were successfully visualized. Although we analyzed the data from two-stroke diesel engine, our method can be applied to various types of marine engine.

16.
ACS Appl Mater Interfaces ; 12(35): 39372-39380, 2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-32805924

RESUMO

This study reports on the effect of a bilayer period on the growth behavior, microstructure evolution, and electrical properties of atomic layer deposition (ALD) deposited In-Zn-O (IZO) films, fixing the ALD cycle ratio of In-O/Zn-O as 9:1. Here, the bilayer period is defined as the total number of ALD cycles in one supercycle of In-O and Zn-O by alternately stacking Zn-O and In-O layers at a temperature of 220 °C. IZO films with a bilayer period from 10 to 40 cycles, namely, IZO[In-O/Zn-O = 9:1] to IZO[36:4], result to form an amorphous phase with a resistivity of 4.94 × 10-4 Ω·cm. However, by increasing the bilayer period above 100 cycles, the IZO films begin to form a mixed amorphous-nanocrystalline microstructure, resulting from the limited intermixing at the interfaces. Concomitantly, the overall film resistivity is considerably increased with a simultaneous decrease in both the carrier mobility and the concentration. These results not only reveal the importance of the bilayer period in designing the ALD stacking sequence in the ALD-IZO, but also provide the possibility of forming various multilayered materials with different electrical properties.

17.
ACS Appl Mater Interfaces ; 12(27): 30932-30940, 2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32400151

RESUMO

Both interlayer-undoped and interlayer-doped multilayer graphenes were prepared by the multiple transfers of graphene layers with multiple Cu etching (either dopant-free or doped during etching) and transfer, and the effect of interface properties on the electrical properties of multilayer graphene was investigated by varying the number of layers from 1 to 12. In both the cases, the sheet resistance decreased with increasing number of layers from 700 to 104 Ω/sq for the interlayer-undoped graphene and from 280 to 25 Ω/sq for the interlayer-doped graphene. Further, Hall measurements revealed that the origins of the sheet resistance reduction in the two cases are different. In the interlayer-undoped graphene, the sheet resistance decreased because of the increase in mobility with the addition of inner layers, which has a low carrier density and a high carrier mobility. On the other hand, it decreased because of the increase in sheet carrier density in the interlayer-doped multilayer graphene. The mobility and carrier density variations in both the cases were confirmed by fitting with the model of Hall effect in the heterojunction. In addition, we found that surface property modification by the doping of the top layer and the formation of double-layer graphene with different partial coverages allow the separate control of carrier density and mobility. Our study provides an effective approach for controlling the properties of multilayer graphene for electronic applications.

18.
Sensors (Basel) ; 20(6)2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32178345

RESUMO

The fluctuation of the oil price and the growing requirement to reduce greenhouse gas emissions have forced ship builders and shipping companies to improve the energy efficiency of the vessels. The accurate prediction of the required propulsion power at various operating condition is essential to evaluate the energy-saving potential of a vessel. Currently, a new ship is expected to use the ISO15016 method in estimating added resistance induced by external environmental factors in power prediction. However, since ISO15016 usually assumes static water conditions, it may result in low accuracy when it is applied to various operating conditions. Moreover, it is time consuming to apply the ISO15016 method because it is computationally expensive and requires many input data. To overcome this limitation, we propose a data-driven approach to predict the propulsion power of a vessel. In this study, support vector regression (SVR) is used to learn from big data obtained from onboard measurement and the National Oceanic and Atmospheric Administration (NOAA) database. As a result, we show that our data-driven approach shows superior performance compared to the ISO15016 method if the big data of the solid line are secured.

19.
ACS Appl Mater Interfaces ; 12(12): 14331-14340, 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32017528

RESUMO

Although graphene has considerable potential as a next-generation transparent conducting electrode (TCE) material owing to its excellent optical transparency and flexibility, its electrical properties require further improvement for industrial application. This study reports a pathway of doping graphene by selective atomic layer deposition (ALD) of metals to elevate the electrical conductivity of graphene. Introduction of a novel Pt precursor [dimethyl(N,N-dimethyl-3-butene-1-amine-N)platinum(II); C8H19NPt; DDAP] facilitates a low-temperature (165 °C) process. The sheet resistance (Rs) of graphene is reduced significantly from 471 to 86.8 Ω sq-1 after 200 cycles of Pt ALD, while the optical transmittance at 550 nm (T) is maintained above 90% up to 200 cycles due to the selective growth of Pt on the defects of graphene. Furthermore, comprehensive analysis, including metal (Ru, Pt, and Ni) ALD on graphene, metal (Ru, Pt, Ni, Au, and Co) evaporation on graphene, and change in the ALD chemicals, demonstrates that ALD allows efficient graphene doping and the oxygen affinity of the metal is one of the key properties for efficient graphene doping. Finally, Pt ALD is applied to a multilayer graphene to further reduce Rs down to 75.8 Ω sq-1 yet to be highly transparent (T: 87.3%) after 200 cycles. In summary, the selective ALD of metals opens a way of improving the electrical properties of graphene to a level required for the industrial TCE application and has the potential to promote development of other types of functional metal-graphene composites.

20.
RSC Adv ; 10(59): 35671-35680, 2020 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-35517093

RESUMO

The oxidation kinetics of Cu through graphene were evaluated from the surface coverage of Cu oxide (F ox) by varying the oxidation time (t ox = 10-360 min) and temperature (T ox = 180-240 °C) under an air environment. F ox, as a function of time, well followed the Johnson-Mehl-Avrami-Kolmogorov equation; thus, the activation energy of Cu oxidation was estimated as 1.5 eV. Transmission electron microscopy studies revealed that Cu2O formed on the top of the graphene at grain boundaries (G-GBs), indicating that Cu2O growth was governed by the out-diffusion of Cu through G-GBs. Further, the effect of Cu oxidation on graphene quality was investigated by measuring the electrical properties of graphene after transferring. The variation of the sheet resistance (R s) as a function of t ox at all T ox was converted into one curve as a function of F ox. R s of 250 Ω sq-1 was constant, similar to that of as-grown graphene up to F ox = 15%, and then increased with F ox. The Hall measurement revealed that the carrier concentration remained constant in the entire range of F ox, and R s was solely related to the decrease in the Hall mobility. The variation in Hall mobility was examined according to the graphene percolation probability model, simulating electrical conduction on G-GBs during Cu2O evolution. This model well explains the constant Hall mobility within F ox = 15% and drastic F ox degradation of 15-50% by the concept that the electrical conduction of graphene is disconnected by Cu2O formation along with the G-GBs. Therefore, we systematically developed the oxidation kinetics of Cu through graphene and simultaneously examined the changes in the electrical properties of graphene.

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