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1.
Nano Lett ; 24(13): 3978-3985, 2024 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-38451178

RESUMEN

We investigated atomic site occupancy for the Si dopant in Si-doped κ-Ga2O3(001) using photoelectron spectroscopy (PES) and photoelectron holography (PEH). From PES and PEH, we found that the Si dopant had one chemical state, and three types of inequivalent Si substitutional sites (SiGa) were formed. The ratios for the inequivalent tetrahedral, pentahedral, and octahedral SiGa sites were estimated to be 55.0%, 28.1%, and 16.9%, respectively. Higher (lower) ratios for the three inequivalent SiGa sites may come from a lower (higher) formation energy. The Tetra (Octa) SiGa site has the highest (lowest) ratio of the three SiGa sites since it has the lowest (highest) formation energy. We suggest that the tetrahedral SiGa site is due to the active dopant site, whereas the pentahedral and octahedral SiGa sites can be attributed to the inactive dopant sites for Si-doped κ-Ga2O3(001).

2.
Oncology ; 100(6): 303-312, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35114665

RESUMEN

BACKGROUND AND AIMS: Radiofrequency ablation (RFA) has replaced percutaneous ethanol injection (PEI) as the treatment of choice for hepatocellular carcinoma (HCC); however, control of local tumor progression (LTP) remains a challenge in perivascular HCC. The aim of this study was to determine whether PEI added to RFA can reduce the LTP rate in perivascular HCC patients. METHODS: We retrospectively analyzed 167 patients, with 197 newly diagnosed HCC nodules with peritumoral vessels, who underwent either RFA plus PEI or RFA monotherapy as the first-line treatment between June 2001 and April 2015. Ethanol was injected inside the tumor close to the peritumoral vessels in the combination therapy group. Patients were matched 1:1 according to their propensity scores to reduce selection bias; cumulative LTP was then analyzed using log-rank tests and Cox proportional hazard regression analyses. RESULTS: The two matched groups comprised 62 tumors each. The overall median follow-up period was 34 months (range, 1-140 months). In the RFA plus PEI group, the cumulative LTP rates were 5.7%, 15.5%, and 20.4% at 1, 3, and 5 years, respectively; in the RFA monotherapy group, the rates were 13.2%, 32.0%, and 40.2%, respectively. The rates were significantly lower in the RFA plus PEI group (p = 0.032). Cox proportional hazard regression analysis showed that PEI combination treatment was significantly associated with a reduced risk of local HCC recurrence (hazard ratio, 0.44; 95% confidence interval, 0.19-0.93; p = 0.031). DISCUSSION/CONCLUSION: The risk of LTP after RFA for perivascular HCC can be significantly reduced by injecting ethanol close to the peritumoral vessels.


Asunto(s)
Carcinoma Hepatocelular , Ablación por Catéter , Neoplasias Hepáticas , Ablación por Radiofrecuencia , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/cirugía , Etanol , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/cirugía , Puntaje de Propensión , Estudios Retrospectivos , Resultado del Tratamiento
3.
J Clin Ultrasound ; 50(6): 832-842, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34882818

RESUMEN

Porphyria cutanea tarda (PCT) is commonly diagnosed in cases where multiple hyperechoic nodules are observed in the liver. Pathologically, these nodules associated with PCT are focal fatty deposits. We report here, seven cases of PCT with fatty changes over multiple foci in the liver. Furthermore, the characteristics of ultrasonography (US) findings of 32 previously reported cases are summarized. The US features of these nodules showed a homogenous hyperechoic or hyperechoic rim pattern, partial confluence, and no mass effect in the vascular structures. Because multiple hyperechoic liver nodules occasionally mimic malignancies, and because their diagnosis can be challenging, clinicians should consider checking urine porphyrin levels to rule out PCT when such nodules are observed on US.


Asunto(s)
Porfiria Cutánea Tardía , Humanos , Porfiria Cutánea Tardía/complicaciones , Porfiria Cutánea Tardía/diagnóstico por imagen , Ultrasonografía/efectos adversos
4.
ACS Omega ; 9(24): 25968-25975, 2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38911734

RESUMEN

In order to obtain thermally stable thin-film materials with high dielectric constant, A2B2O7 thin films (Sr2Ta2O7, Sr2Nb2O7, La2Zr2O7, and La2Ti2O7) containing Sr or La and their solid solutions were grown on Pt/Ti/SiO2/Si substrates by RF sputtering and their crystal structures and dielectric properties were investigated. The Sr2Ta2O7 and La2Ti2O7 films exhibit highly oriented crystal structures. By contrast, the Sr2Nb2O7 and La2Zr2O7 films exhibit polycrystalline structures. The leakage properties of the Sr-containing films are lower and more stable in the high-temperature region (up to 300 °C) than those of the La-containing films. Among the investigated films, the Sr2Ta2O7 film grown at 500 °C and annealed at 900 °C shows the most stable dielectric constant with respect to temperature in the temperature range from room temperature to 300 °C. In addition, the xSr2Ta2O7-(1-x)La2Ti2O7 solid solutions exhibit enhanced dielectric properties at x = 0.35. The dielectric constant is greater than 100, and its variation with temperature is less than 10%. The Sr-containing A2B2O7 ferroelectric thin films have potential applications as high-temperature film capacitors that can operate at temperatures as high as 300 °C.

5.
Chem Sci ; 15(24): 9147-9154, 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38903239

RESUMEN

Lattice strain effects on the piezoelectric properties of crystalline ferroelectrics have been extensively studied for decades; however, the strain dependence of the piezoelectric properties at nano-level has yet to be investigated. Herein, a new overview of the super-strain of nanoporous polycrystalline ferroelectrics is reported for the first time using a nanoengineered barium calcium zirconium titanate composition (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCZT). Atomic-level investigations show that the controlled pore wall thickness contributes to highly strained lattice structures that also retain the crystal size at the optimal value (<30 nm), which is the primary contributor to high piezoelectricity. The strain field derived from geometric phase analysis at the atomic level and aberration-corrected high-resolution scanning transmission electron microscopy (STEM) yields of over 30% clearly show theoretical agreement with high piezoelectric properties. The uniqueness of this work is the simplicity of the synthesis; moreover the piezoresponse d 33 becomes giant, at around 7500 pm V-1. This response is an order of magnitude greater than that of lead zirconate titanate (PZT), which is known to be the most successful ferroelectric over the past 50 years. This concept utilizing nanoporous BCZT will be highly useful for a promising high-density electrolyte-free dielectric capacitor and generator for energy harvesting in the future.

6.
Cureus ; 15(1): e34275, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36855497

RESUMEN

A 30-year-old woman (daughter) was diagnosed to have primary biliary cholangitis (PBC) with autoimmune hepatitis (AIH) overlap syndrome. Although she was started on prednisolone and ursodeoxycholic acid (UA), she eventually died of hepatic failure with gastrointestinal hemorrhage seven months after the initial hospitalization. A 60-year-old woman (mother) was diagnosed with PBC with alcoholic liver cirrhosis, was treated with UA, and had no disease progression. These familial PBC patients had different clinical courses. While the mother was negative for the anti-glycoprotein 210 (anti-gp210) antibody, the daughter was positive for the same. These findings suggest that anti-gp210 antibody positivity affects the prognosis of PBC, even in familial cases.

7.
Intern Med ; 62(18): 2667-2673, 2023 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-36754408

RESUMEN

We herein report two cases of rapidly progressive fatty liver (FL) disease due to pancreatic exocrine insufficiency (PEI) without a surgical history. Two women, 59 and 72 years old, with no history of abdominal surgery presented to our hospital with severe anorexia and nausea persisting for one week. Examinations revealed progressive, marked FL disease with hepatomegaly and PEI, for which pancreatic enzyme replacement therapy was effective. Commonly known causes of PEI include chronic pancreatitis, abdominal surgery (e.g. pancreaticoduodenectomy), pancreatic cancer, and obstruction of the pancreatic duct, none of which were present in either of these two cases.


Asunto(s)
Insuficiencia Pancreática Exocrina , Enfermedad del Hígado Graso no Alcohólico , Neoplasias Pancreáticas , Pancreatitis Crónica , Humanos , Femenino , Persona de Mediana Edad , Anciano , Insuficiencia Pancreática Exocrina/complicaciones , Insuficiencia Pancreática Exocrina/tratamiento farmacológico , Páncreas , Enfermedad del Hígado Graso no Alcohólico/complicaciones , Neoplasias Pancreáticas/complicaciones , Terapia de Reemplazo Enzimático
8.
ACS Nano ; 17(15): 14981-14989, 2023 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-37458690

RESUMEN

N,N-Dimethylformamide (DMF) is an essential solvent in industries and pharmaceutics. Its market size range was estimated to be 2 billion U.S. dollars in 2022. Monitoring DMF in solution environments in real time is significant because of its toxicity. However, DMF is not a redox-active molecule; therefore, selective monitoring of DMF in solutions, especially in polar aqueous solutions, in real time is extremely difficult. In this paper, we propose a selective DMF sensor using a molybdenum disulfide (MoS2) field-effect transistor (FET). The sensor responds to DMF molecules but not to similar molecules of formamide, N,N-diethylformamide, and N,N-dimethylacetamide. The plausible atomic mechanism is the oxygen substitution sites on MoS2, on which the DMF molecule shows an exceptional orientation. The thin structure of MoS2-FET can be incorporated into a microfluidic chamber, which leads to DMF monitoring in real time by exchanging solutions subsequently. The designed device shows DMF monitoring in NaCl ionic solutions from 1 to 200 µL/mL. This work proposes the concept of selectively monitoring redox-inactive molecules based on the nonideal atomic affinity site on the surface of two-dimensional semiconductors.

9.
Intern Med ; 62(24): 3631-3636, 2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-37121750

RESUMEN

We herein report a case of hepatitis C virus (HCV)-associated cryoglobulinemic livedo reticularis in a woman in her 60s that improved with direct-acting antivirals (DAAs). Hyperpigmentation was observed in both lower legs, and a skin biopsy confirmed livedo reticularis, suggesting a relationship with cryoglobulinemia and HCV infection. DAAs with an NS5A inhibitor+NS3/4A protease inhibitor (glecaprevir/pibrentasvir) were administered for eight weeks, and a sustained virological response (SVR) was obtained. The disappearance of serum cryoglobulin was confirmed approximately two years after an SVR was obtained and livedo reticularis was improved. DAA therapy can be an effective therapeutic option for extrahepatic complications associated with HCV infection.


Asunto(s)
Crioglobulinemia , Hepatitis C Crónica , Hepatitis C , Livedo Reticularis , Femenino , Humanos , Antivirales , Hepacivirus , Hepatitis C Crónica/complicaciones , Hepatitis C Crónica/tratamiento farmacológico , Crioglobulinemia/complicaciones , Crioglobulinemia/tratamiento farmacológico , Livedo Reticularis/etiología , Livedo Reticularis/complicaciones , Hepatitis C/complicaciones , Hepatitis C/tratamiento farmacológico
10.
Intern Med ; 2023 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-37866915

RESUMEN

Cornelia de Lange syndrome (CdLS) is a congenital disorder occasionally associated with congenital portosystemic shunt (CPSSs). We herein report a patient with CdLS and CPSS who developed hepatocellular adenomas (HCAs). The patient presented to our hospital for the further investigation of newly diagnosed liver tumors. Imaging findings and pathological examination results indicated that the liver tumors were inflammatory HCAs that subsequently shrank following transcatheter arterial embolization (TAE). Patients with CdLS and CPSS are at risk of developing HCAs, and TAE may be an effective management strategy for HCA in these patients.

11.
Intest Res ; 21(4): 471-480, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37559192

RESUMEN

BACKGROUND/AIMS: The frequency and details of nonalcoholic fatty liver disease (NAFLD) complications in patients with inflammatory bowel disease (IBD) remain unclear. This study aimed to clarify characteristics of NAFLD in patients with IBD. METHODS: We retrospectively identified and enrolled patients with IBD diagnosed with or without NAFLD by undergoing abdominal computed tomography (CT) at our institution between 2005 and 2020. The primary endpoint was the complication rate of NAFLD in patients with IBD. Secondary endpoints were the clinical characteristics of nonobese patients with IBD and comorbid NAFLD and their association with nutritional and inflammatory parameters. RESULTS: Twenty-one (21.9%) of 96 eligible patients with IBD also had NAFLD. In nonobese patients (defined as patients with a body mass index <25 kg/m2), C-reactive protein (CRP; P<0.001) and alanine aminotransferase (P=0.018) levels were higher and the albumin level (P=0.005) and prognostic nutritional index (PNI; P=0.002) values were lower in patients with NAFLD than in those without NAFLD. The PNI value was positively correlated (P<0.001) and the CRP level was negatively correlated (P=0.001) with the hepatosplenic ratio. However, in the NAFLD combined group, PNI (P<0.05) and CRP values (P<0.001) were improved over time after CT imaging by continuing IBD treatment. CONCLUSIONS: Worsening nutritional and inflammatory status in IBD patients is associated with complications of NAFLD. Diagnosis of NAFLD in IBD patients using CT imaging might be useful not only for early detection of NAFLD but also in assessing the need for therapeutic intervention for IBD.

12.
ACS Omega ; 7(23): 19380-19387, 2022 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-35721998

RESUMEN

The ability to control the polarity of an all-sputtered epitaxial GaN/AlN/Al film on a Si(111) substrate via intermediate oxidization was investigated. A stable surface of GaN on a Si substrate is a N-terminated surface (-c surface); hence, for electric device applications, the Ga-terminated surface (+c surface) is preferable. The GaN/AlN/Al film on Si(111) showed a -c surface, as confirmed by time-of-flight low-energy atom scattering spectroscopy (TOFLAS) and X-ray photoelectron spectroscopy (XPS). The AlN layer was intentionally oxidized via air exposure during film growth. The GaN surface subjected to the oxidization process had the +c surface. Secondary-ion mass spectrometry measurements indicated a high oxygen concentration after the intentional oxidization. However, the intentional oxidization degraded the crystallinity of the GaN/AlN layer. By changing the oxidization point and repeating the GaN/AlN growth, the crystallinity of GaN was recovered. Such polarity control of GaN on Si grown by sputtering shows strong potential for the fabrication of large-diameter +c-GaN template substrates at low cost.

13.
Intern Med ; 60(19): 3107-3112, 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-33867388

RESUMEN

We report a case of anorexia nervosa (AN) with gastroesophageal varices (GEV) in a 36-year-old woman. The patient presented to our hospital with progressive bloating due to severe ascites. She had no history of alcohol intake. Esophagogastroduodenoscopy and enhanced computed tomography revealed GEV and multiple hepatic nodules, respectively. The histological examination of a liver biopsy specimen revealed similar features to nonalcoholic fatty liver disease and showed hyperplastic nodules that were suspected to be related to the uneven distribution of portal blood flow in the liver. In conclusion, patients with long-term AN should undergo abdominal imaging to detect signs of portal hypertension.


Asunto(s)
Anorexia Nerviosa , Várices Esofágicas y Gástricas , Hipertensión Portal , Várices , Adulto , Anorexia Nerviosa/complicaciones , Anorexia Nerviosa/diagnóstico , Várices Esofágicas y Gástricas/diagnóstico , Várices Esofágicas y Gástricas/etiología , Femenino , Humanos , Hipertensión Portal/complicaciones , Hipertensión Portal/diagnóstico , Hígado/diagnóstico por imagen
14.
Nat Comput Sci ; 1(7): 470-478, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38217117

RESUMEN

Existing data-driven approaches for exploring high-entropy alloys (HEAs) face three challenges: numerous element-combination candidates, designing appropriate descriptors, and limited and biased existing data. To overcome these issues, here we show the development of an evidence-based material recommender system (ERS) that adopts Dempster-Shafer theory, a general framework for reasoning with uncertainty. Herein, without using material descriptors, we model, collect and combine pieces of evidence from data about the HEA phase existence of alloys. To evaluate the ERS, we compared its HEA-recommendation capability with those of matrix-factorization- and supervised-learning-based recommender systems on four widely known datasets of up-to-five-component alloys. The k-fold cross-validation on the datasets suggests that the ERS outperforms all competitors. Furthermore, the ERS shows good extrapolation capabilities in recommending quaternary and quinary HEAs. We experimentally validated the most strongly recommended Fe-Co-based magnetic HEA (namely, FeCoMnNi) and confirmed that its thin film shows a body-centered cubic structure.

15.
Hepatol Int ; 15(2): 392-404, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33398776

RESUMEN

BACKGROUND: Recent studies have suggested that several types of toxic bile acids (BAs) are involved in the pathogenesis of non-alcoholic steatohepatitis (NASH). In the present study, we aimed to determine whether elobixibat, an ileal bile acid transporter (IBAT) inhibitor, would ameliorate NASH in mice. METHODS: C57BL/6N mice were fed a methionine and choline-deficient (MCD) to induce NASH or standard diet as control for 8 weeks (n = 5 per group). The MCD diet-fed mice were administered elobixibat 5 days a week for 4 weeks by gavage (n = 5). The effects of the treatments on liver histopathology, proinflammatory cytokine concentrations, intestinal epithelial tight junctions, and the intestinal microbial composition were then assessed. RESULTS: In MCD-fed mice, hepatic fibrosis and inflammatory cell infiltration developed, and the serum aspartate transaminase activity and BA concentration were higher than the control. In addition, the proinflammatory cytokine concentrations were high in the liver and mesenteric lymph nodes (MLN), and the expression of intestinal epithelium tight junction proteins, claudin1, was increased. In the intestinal microbial composition, the abundance of the Lachnospiraceae and Ruminococcaeae were decreased, whereas that of the Enterobacteriaceae was increased. Treatment with elobixibat reduced the serum BA and increased the fecal BA concentration, and ameliorated the liver inflammation and fibrosis. It also reduced the expression of proinflammatory cytokines in the liver and MLNs, and transforming growth factor-ß expression in the liver. Finally, elobixibat normalized intestinal tight junction protein level and the composition of the intestinal microbiota. CONCLUSION: Elobixibat ameliorates NASH-related histopathology, reduces cytokine expression, and normalizes the intestinal microbial composition in MCD-fed mice, which suggests that it may represent a promising candidate for the therapy of NASH.


Asunto(s)
Dipéptidos/uso terapéutico , Enfermedad del Hígado Graso no Alcohólico , Tiazepinas/uso terapéutico , Animales , Proteínas Portadoras , Modelos Animales de Enfermedad , Íleon , Glicoproteínas de Membrana , Ratones , Ratones Endogámicos C57BL , Enfermedad del Hígado Graso no Alcohólico/tratamiento farmacológico
16.
ACS Comb Sci ; 22(9): 433-439, 2020 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-32659073

RESUMEN

The correlation between the crystal structure and valence band structure of a (GaxIn1-x)2O3 solid solution system was investigated by using combinatorial synthesis. At a low Ga content of (GaxIn1-x)2O3 with a single-phase cubic In2O3 crystal structure, a surface electron accumulation layer (SEAL), which is an important electrical phenomenon in In2O3, was confirmed. When the Ga content increased to approximately x = 0.4, mixed crystal structures of Ga2O3 and In2O3 were produced. Above x = 0.5, the dominant valence band structure was attributed to Ga2O3, the SEAL disappeared, and the sheet resistance increased greatly by 5 orders of magnitude or more. The in-gap state and valence band structure of the (GaxIn1-x)2O3 solid solution system were strongly affected by Ga2O3; however, the valence band maximum position shifted to a higher binding energy.


Asunto(s)
Técnicas Químicas Combinatorias , Germanio/química , Indio/química , Oxígeno/química , Soluciones
17.
ACS Appl Mater Interfaces ; 12(36): 40186-40193, 2020 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-32805866

RESUMEN

Intensive research is being conducted into highly efficient and cheap nanoscale materials for the electrocatalytic oxidation of water. In this context, we built heterostructures of multilayered CoNi-cyanide bridged coordination (CoNi-CP) nanosheets and graphene oxide (GO) sheets (CoNi-CP/GO) as a source for heterostructured functional electrodes. The layered CoNi-CP/GO hybrid components heated in nitrogen gas (N2) at 450 °C yield CoNi-based carbide (CoNi-C) through thermal decomposition of CoNi-CP, while GO is converted into reduced GO (rGO) to finally form a CoNi-C/rGO-450 composite. The CoNi-C/rGO-450 composite shows a reasonable efficiency for oxygen evolution reaction (OER) through water oxidations in alkaline solution. Meanwhile, regulated annealing of CoNi-CP/GO in N2 with thiourea at 450 and 550 °C produces CoNi-based sulfide (CoNi-S) rather than CoNi-C between rGO sheets co-doped by nitrogen (N) and sulfur (S) heteroatoms (NS-rGO) to form CoNi-S/NS-rGO-450 and CoNi-S/NS-rGO-550 composites, respectively. The CoNi-S/NS-rGO-550 shows the best efficiency for electrocatalytic OER among all electrodes with an overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 79.5 mV dec-1. By applying the iR compensation to remove resistance of the solution (2.1 Ω), the performance is further improved to achieve a current density of 10 mA cm-2 at an overpotential of 274 mV with a Tafel slope of 70.5 mV dec-1. This result is expected to be a promising electrocatalyst compared to the currently used electrocatalysts and a step for fuel cell applications in the future.

18.
Heliyon ; 6(6): e04214, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32613109

RESUMEN

As technology has improved in recent years, it has become possible to create new valuable functions by combining various devices and sensors in a network. This concept is referred to as the Internet of Things (IoT), and predictive maintenance is a new valuable function associated with the IoT. In large-scale experimental facilities with many researchers, it is not desirable that experiments cannot be performed due to sudden failure of equipment. For this reason, it is important to predict the failure in advance based on the measurement results of sensors and to perform repairs in a planned manner. On the Q-shu University experiment with steady-state spherical tokamak (QUEST) large experimental device, it is necessary to drive a large current of 50 kA, and the diagnosis of its power line deterioration is well performed as predictive maintenance through the evaluation of its contact resistances of several micro ohms order on the network. In addition, as an example of the IoT, mechanisms to assist safe operation, such as a sound alarm system and an entrance management system, are built by sharing experimental information between devices via the network.

19.
ACS Comb Sci ; 22(12): 858-866, 2020 12 14.
Artículo en Inglés | MEDLINE | ID: mdl-33146510

RESUMEN

Thin films of two types of high-entropy oxides (HEOs) have been deposited on 76.2 mm Si wafers using combinatorial sputter deposition. In one type of the oxides, (MgZnMnCoNi)Ox, all the metals have a stable divalent oxidation state and similar cationic radii. In the second type of oxides, (CrFeMnCoNi)Ox, the metals are more diverse in the atomic radius and valence state, and have good solubility in their sub-binary and ternary oxide systems. The resulting HEO thin films were characterized using several high-throughput analytical techniques. The microstructure, composition, and electrical conductivity obtained on defined grid maps were obtained for the first time across large compositional ranges. The crystalline structure of the films was observed as a function of the metallic elements in the composition spreads, that is, the Mn and Zn in (MgZnMnCoNi)Ox and Mn and Ni in (CrFeMnCoNi)Ox. The (MgZnMnCoNi)Ox sample was observed to form two-phase structures, except single spinel structure was found in (MgZnMnCoNi)Ox over a range of Mn > 12 at. % and Zn < 44 at. %, while (CrFeMnCoNi)Ox was always observed to form two-phase structures. Composition-controlled crystalline structure is not only experimentally demonstrated but also supported by density function theory calculation.


Asunto(s)
Técnicas Químicas Combinatorias , Entropía , Metales Pesados/química , Óxidos/química , Ensayo de Materiales
20.
ACS Omega ; 4(12): 14680-14687, 2019 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-31552307

RESUMEN

Mesoporous hafnium dioxide (HfO2) thin films (around 20 nm thick) were fabricated by a sol-gel-based spin-coating process, followed by an annealing process at 600 °C to realize the ion-conducting media for the ionics (e.g., Na+ and K+ for rechargeable ion batteries). Another film of aluminum metal (10 nm thick) was deposited by direct current sputtering to soak into the mesopores. A monitored thermal treatment process at 500 °C in the air yields mesostructured HfO2/Al2O3 composite thin films. However, aluminum dioxide (Al2O3) is formed during annealing as an insulating film to reduce the leakage current while retaining the ionic conductivity. The obtained mesostructured HfO2/Al2O3 films show a leakage current at 3.2 × 10-9 A cm-2, which is significantly smaller than that of the mesoporous HfO2 film (1.37 × 10-5 A cm-2) or HfO2/Al film (0.037 A cm-2) at a bias voltage of 1.0 V, which is enough for ion conduction. In the meantime, among all the thin films, the mesostructured HfO2/Al2O3 composite thin films display the smallest Nyquist arc diameter in 1.0 M KOH electrolyte, implying a lower impedance at the electrode/electrolyte interface and reflecting a better ion diffusion and movement.

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