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1.
Luminescence ; 38(5): 625-636, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36929164

RESUMO

The present investigation deals with the effect of calcination temperature on the structural and thermoluminescent (TL) properties of Zn2 SiO4 materials. For this study, Zn2 SiO4 was prepared via a simple hydrothermal route and calcinated at temperatures from 700°C to 1100°C in an air atmosphere. TL data of all Zn2 SiO4 samples showed two peaks at around 240°C and 330°C due to the formation of the luminescence centre during X-ray irradiation. More interestingly, the Zn2 SiO4 sample calcinated at 900°C exhibited a shift in the TL peak (282°C and 354°C) with an optimal TL intensity attributed to its good crystallinity with a well-defined hexagonal plate-like morphology. X-ray-irradiated Zn2 SiO4 samples calcinated at 900°C exhibited a high-temperature TL glow curve peak, suggesting that the present material could be used for high-temperature dosimetry applications.


Assuntos
Luminescência , Zinco , Temperatura , Raios X , Dosimetria Termoluminescente , Difração de Raios X
2.
Small ; 16(1): e1905868, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31788955

RESUMO

Beyond a traditional view that metal nanoparticles formed upon electrochemical reaction are inactive against lithium, recently their electrochemical participations are manifested and elucidated as catalytic and interfacial effects. Here, ruthenium metal composed of ≈5 nm nanoparticles is prepared and the pure ruthenium as a lithium-ion battery anode for complete understanding on anomalous lithium storage reaction mechanism is designed. In particular, the pure metal electrode is intended for eliminating the electrochemical reaction-derived Li2 O phase accompanied by catalytic Li2 O decomposition and the interfacial lithium storage at Ru/Li2 O phase boundary, and thereby focusing on the ruthenium itself in exploring its electrochemical reactivity. Intriguingly, unusual lithium storage not involving redox reactions with electron transfer but leading to lattice expansion is identified in the ruthenium electrode. Size-dependent charge redistribution at surface enables additional lithium adsorption to occur on the inactive but more environmentally sensitive nanoparticles, providing innovative insight into dynamic electrode environments in rechargeable lithium chemistry.

3.
Environ Res ; 172: 649-657, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30878736

RESUMO

The catalytic oxidation of toluene with ozone at room temperature was carried out over hierarchically ordered mesoporous catalysts (CeO2 (meso), Mn2O3 (meso), ZrO2 (meso), and γ-Al2O3 (meso)) and Al2O3 with various textural properties and phases (γ-Al2O3 (meso), γ-Al2O3 (13 nm), and α-Al2O3) to examine the effects of the nature of the catalyst on the catalytic activity. The catalysts were characterized by N2-physisorption measurements, powder X-ray diffraction, temperature programmed reduction, X-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy. Among the ordered mesoporous catalysts, γ-Al2O3 (meso) had the highest toluene removal efficiency because of its highest surface area and pore volume, which in turn was selected for further investigation. Manganese (Mn) was introduced to various Al2O3 to improve the toluene removal efficiency. Comparing the Mn-loaded catalysts supported on various Al2O3 with different crystalline phases or pore structures, Mn/γ-Al2O3 (meso), had the highest catalytic activity as well as the highest CO2/CO ratio. The higher activity was attributed to the larger surface area, weaker interaction between Mn and Al2O3, and larger portion of Mn2O3 phase. The increase in ozone concentration led to an improvement in the carbon balance but this enhancement was insufficient due to the deposition of by-products on the catalyst. After long term tests at room temperature, the reaction intermediates and carbonaceous deposits of the used catalysts were identified.


Assuntos
Técnicas de Química Analítica , Ozônio , Tolueno , Óxido de Alumínio/química , Catálise , Técnicas de Química Analítica/métodos , Manganês/química , Ozônio/química , Temperatura , Tolueno/isolamento & purificação
4.
Small ; 14(43): e1702985, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29280277

RESUMO

Nanostructured materials make a considerable impact on the performance of lithium-storage characteristics in terms of the energy density, power density, and cycle life. Direct experimental observation, by a comparison of controlled nanostructural uniformity of electrode materials, reveals that the lithium-storage behaviors of mesoporous MoO2 and CuO electrodes are linearly correlated with their nanostructural uniformity. Reversible capacities of mesoporous MoO2 and CuO electrodes with well-developed nanostructures (1569 mA h g-1 for MoO2 and 1029 mA h g-1 for CuO) exceed their theoretical capacity based on the conversion reaction (838 mA h g-1 for MoO2 and 674 mA h g-1 for CuO). Given that exact understanding of the origin of the additional capacity is essential in maximizing the energy density of electrode material, this work may help to gain some insights into the development of high energy-density lithium-storage materials for next-generation lithium rechargeable batteries.

5.
J Nanosci Nanotechnol ; 18(2): 1427-1430, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29448605

RESUMO

Mesoporous CuCe-based ternary metal oxides were synthesized using KIT-6 as a hard template through a nano-casting method. The mesoporous CuCe-based metal oxides were applied to the catalytic decomposition of the ammonium dinitramide-based liquid monopropellant. The decomposition onset temperature over the meso-CuCe ternary metal oxides was much lower than that over the CuCeOx catalyst prepared by conventional precipitation method. Higher activity of the meso-CuCe ternary metal oxides is attributed to higher surface area and larger pore size of the meso-CuCe ternary metal oxides than those of the conventional CuCe oxide. The highest activity of meso-CuCeZr catalyst among the meso-CuCe ternary metal oxide catalysts is likely due to the highest mesoporosity.

6.
J Nanosci Nanotechnol ; 18(1): 353-358, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29768853

RESUMO

Ordered mesoporous Cu-Mn binary metal oxide (meso-CuMnOx) catalysts were successfully synthesized by a hard-templating method from a mesoporous silica template with a cubic Ia3d mesostructure (KIT-6) or hydrophobic KIT-6, exhibiting a well-developed crystalline framework, a regular pore size distribution and a high surface area. The copper and manganese elements in the mesoporous Cu-Mn binary metal oxides (meso-CuMnOx-N and meso-CuMnOx-HP), obtained from the KIT-6 and hydrophobic KIT-6, respectively, were homogeneously dispersed in the whole particles. The activities of meso-CuMnOx catalysts for the decomposition of a liquid monopropellant containing an energetic ionic liquid, ammonium dinitramide, were much higher than that over a CuMnOx catalyst prepared by a conventional precipitation method. This is attributed to the well-developed mesoporosity of the meso-CuMnOx catalysts. Among the mesoporous CuMnOx catalysts, the decomposition onset temperature over meso-CuMnOx-HP (87.9 °C) was found to be lower than that over meso-CuMnOx-N (100.4 °C), probably due to its higher mesoporosity and surface area.

7.
J Nanosci Nanotechnol ; 18(9): 6300-6303, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29677785

RESUMO

The thermal and catalytic pyrolysis of Pinus densiflora (P. densiflora) were performed to test the catalytic cracking efficiency of two mesoporous Al2O3 catalysts with different surface areas. Thermogravimetric analysis (TGA) of P. densiflora showed that the differential TG (DTG) peak heights obtained from catalytic pyrolysis were smaller than those of non-catalytic pyrolysis due to the conversion of the reaction intermediates to coke. Pyrolyzer-gas chromatography/mass spectrometry analysis/flame ionization detection (Py-GC/MS/FID) suggested that using the Al2O3 catalysts, the yields of phenols and levoglucosan decreased with a concomitant increase in the yields of aldehydes, alcohol, ketones, and furans. Between the two catalysts, Al2O3-B prepared by spray pyrolysis showed higher cracking efficiency than Al2O3-A prepared by hydrothermal method because of its larger surface area.

8.
J Korean Med Sci ; 31(1): 131-8, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26770049

RESUMO

Active involvement of anesthesiologists in perioperative management is important to ensure the patients' safety. This study aimed to investigate the state of anesthetic services in Korea by identifying anesthetic service providers. From the insurance claims data of National Health Insurance for 3 yr, the Korean state of anesthetic services was analyzed. The claims for anesthesia from the medical institutions which hire their own anesthesiologist or with an anesthesiologist invitation fee are assumed to be the anesthesia performed by anesthesiologists. The annual anesthetic data were similar during the study period. In 2013, total counts of 2,129,871 were composed with general anesthesia (55%), regional anesthesia (36%) and procedural sedation with intravenous anesthetics (9%). About 80% of total cases of general anesthesia were performed in general hospitals, while more than 60% of the regional anesthesia and sedation were performed in the clinics and hospitals under 100 beds. Non-anesthesiologists performed 273,006 cases of anesthesia (13% of total) including 36,008 of general anesthesia, 143,134 of regional anesthesia, and 93,864 of sedation, mainly in the clinics and hospitals under 100 beds. All procedural sedations in the institutions without direct employed anesthesiologist were performed by non-anesthesiologists. Significant numbers of anesthesia are performed by non-anesthesiologist in Korea. To promote anesthetic services that prioritize the safety of patients, the standard to qualify anesthetic service is required. Surgeons and patients need to enhance their perception of anesthesia, and the payment system should be revised in a way that advocates anesthesiologist-performed anesthetic services.


Assuntos
Anestesia/estatística & dados numéricos , Adulto , Idoso , Bases de Dados Factuais , Feminino , Humanos , Pessoa de Meia-Idade , Programas Nacionais de Saúde , República da Coreia , Inquéritos e Questionários
9.
J Nanosci Nanotechnol ; 15(3): 2441-5, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26413684

RESUMO

Ordered mesoporous MnO, MnO4, Mn2O3 and MnO2 materials with 3-D pore structure were suc- cessfully synthesized via a nano-replication method by using ordered mesoporous silica, KIT-6 (Cubic Ia3d space group mesostructure) as the template under specific oxidation and reduction conditions. Notably, ordered mesoporous MnO with a crystalline wall (rock salt structure) was syn- thesized for the first time, to the best of our knowledge. The synthesis of the ordered mesoporous MnO was achieved by reducing the ordered mesoporous Mn3O4 under an H2 atmosphere, while preserving the ordered mesostructure and crystalline wall throughout the solid/solid transformation. All of the ordered mesoporous manganese oxides with different crystal structures and oxidation states demonstrated almost the same spherical-like morphology with several hundred nanometers of particles. The synthesized ordered mesoporous manganese oxides had uniform dual mesopores (2-3 nm, and ~20 nm) and crystalline frameworks with large surface areas (86-140 m2/g) and pore volumes (0.27-0.33 cm3/g).


Assuntos
Compostos de Manganês/química , Compostos de Manganês/síntese química , Óxidos/química , Óxidos/síntese química , Técnicas de Química Sintética , Oxirredução , Porosidade , Dióxido de Silício/química
10.
J Am Chem Soc ; 136(19): 6786-9, 2014 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-24786337

RESUMO

This work reports the synthesis and application of metal-organic framework (MOF)@microporous organic network (MON) hybrid materials. Coating a MOF, UiO-66-NH2, with MONs forms hybrid microporous materials with hydrophobic surfaces. The original UiO-66-NH2 shows good wettability in water. In comparison, the MOF@MON hybrid materials float on water and show excellent performance for adsorption of a model organic compound, toluene, in water. Chemical etching of the MOF results in the formation of hollow MON materials.

11.
Nanotechnology ; 25(46): 465706, 2014 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-25360800

RESUMO

Highly conductive, solution-processed silver thin-films were obtained at a low sintering temperature of 100 °C in a short sintering time of 10 min by introducing oximes as a potential reductant for silver complex. The thermal properties and reducibility of three kinds of oximes, acetone oxime, 2-butanone oxime, and one dimethylglyoxime, were investigated as a reducing agent, and we found that the thermal decomposition product of oximes (ketones) accelerated the conversion of silver complex into highly conductive silver at low sintering temperature in a short time. Using the acetone oxime, the silver thin-film exhibited the lowest surface resistance (0.91 Ω sq(-1)) compared to those sing other oximes. The silver thin-film also showed a high reflectance of 97.8%, which is comparable to evaporated silver films. We also demonstrated inkjet printed silver patterns with the oxime-added silver complex inks.

12.
J Nanosci Nanotechnol ; 14(3): 2527-31, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24745258

RESUMO

Low-temperature selective catalytic reduction was carried out over various kinds of manganese oxide (MnOx) catalysts. Mesoporous alpha-Mn2O3, commercial bulk Mn2O3, and Mn/SBA-15 were used as the catalyst. The NOx removal performances of the catalysts were compared. Three different amounts of Mn (5, 10, and 15 wt%) were impregnated on SBA-15 to synthesize Mn/SBA-15. The physical and chemical properties of the catalysts were examined by Brunauer-Emmett-Teller, X-ray diffraction, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction analyses. Of all catalysts examined, mesoporous alpha-Mn2O3 exhibited the highest low-temperature SCR de-NOx efficiency, reaching about 90% at 175 degrees C. This is attributed to strong reducing ability and high oxygen mobility of mesoporous alpha-Mn2O3 and well dispersed Mn2O3 in its mesoporous framework.


Assuntos
Compostos de Manganês/química , Óxidos de Nitrogênio/química , Nitrogênio/química , Óxidos/química , Catálise , Recuperação e Remediação Ambiental , Hidrogênio/química , Espectroscopia Fotoeletrônica , Porosidade , Dióxido de Silício/química , Temperatura
13.
J Am Chem Soc ; 135(51): 19115-8, 2013 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-24320628

RESUMO

Hollow microporous organic networks (H-MONs) were prepared by a template method using silica spheres. The shell thickness was delicately controlled by changing the synthetic conditions. The H-MONs were used as a template for the synthesis of nanoparticulate Co3O4 hollows which showed excellent catalytic performance in H2O2 oxidation.

14.
J Nanosci Nanotechnol ; 13(1): 423-6, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23646749

RESUMO

Benzene is one of the target compounds to be removed from air owing to its carcinogenicity. In this study, benzene oxidation with ozone over a MnOx/KIT-6 catalyst was carried out for the first time. MnOx/KIT-6 was synthesized using two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were examined by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, Brunauer-Emmett-Teller (BET) surface area, and N2 adsorption-desorption. The catalytic activity was found to be dependent on the amount of ozone consumed and the dispersion and reducibility of MnOx on the catalyst surface.


Assuntos
Benzeno/química , Benzeno/isolamento & purificação , Manganês/química , Nanopartículas/química , Ozônio/química , Dióxido de Silício/química , Catálise , Oxirredução
15.
J Nanosci Nanotechnol ; 13(4): 2879-84, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23763174

RESUMO

CMK-8, a mesoporous carbon material, was activated using different methods for the adsorption of low-concentration airborne formaldehyde. KOH and ammonia treatments were used to activate CMK-8. A CMK-8 sample was treated with KOH first followed by an ammonia-treatment at 700 degrees C to determine the effect of a combination of the two treatment methods. The adsorbents prepared were characterized by X-ray diffraction, N2 adsorption-desorption and X-ray photoelectron spectroscopy. The KOH treatment increased the concentration of oxygen functional groups, whereas the ammonia-treatment generated a significant amount of nitrogen functional groups. The formaldehyde adsorption efficiency was highest when both KOH- and ammonia-treatments were applied to CMK-8. The ammonia-treated CMK-8 exhibited higher formaldehyde adsorption ability than the KOH-treated one, whereas non-activated CMK-8 showed the lowest formaldehyde adsorption efficiency. The number of nitrogen functional groups and the specific surface area appeared to significantly affect the formaldehyde adsorption capability of the adsorbents, whereas oxygen functional groups played a less important role.

16.
J Nanosci Nanotechnol ; 13(11): 7472-6, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24245276

RESUMO

The catalytic oxidation of benzene was carried out over mesoporous alpha-Mn2O3, MnOx/KIT-6, and bulk commercial Mn oxides (Mn2O3, MnO2, and MnO). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and temperature-programmed reduction analysis. MnOx/KIT-6, prepared by impregnating MnOx on KIT-6, exhibited a low activity for the oxidation of benzene, whereas mesoporous alpha-Mn2O3, manufactured using KIT-6 as the template, showed a high activity. The order of the activities of bulk Mn oxides for benzene decomposition was shown to be Mn2O3 > MnO2 > MnO. Therefore, the high activity of mesoporous alpha-Mn2O3 is attributed to the uniform distribution of highly active Mn2O3 in the mesoporous structure.


Assuntos
Benzeno/química , Compostos de Manganês/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Óxidos/química , Catálise , Teste de Materiais , Oxirredução , Tamanho da Partícula , Porosidade
17.
Medicine (Baltimore) ; 102(46): e35994, 2023 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-37986344

RESUMO

The purpose of this study is to analyze the publicness of medical services in public and private medical institutions, with a focus on treatment performance using National Health Insurance data. Data from the National Health Insurance Service were used to compare the publicness of medical services in public and private medical institutions. Beta regression analysis was conducted after adjusting for the relevant characteristics to identify the impact on the public treatment performance of medical institutions. The public case rate of public health institutions was higher than that of private medical institutions. According to the type of medical care institution, the public case rate was higher in general hospitals and tertiary hospitals than in hospitals. Recently, it has often highlighted that increasing emphasis of profitability in the evaluation of public health institutions is damaging the publicness of medical services. Even in this study, it can be evaluated that the public case rate of public health institutions is not higher than that of private medical institutions.


Assuntos
Programas Nacionais de Saúde , Saúde Pública , Humanos , Hospitais Públicos , Instalações de Saúde , Seguro Saúde
18.
ACS Appl Mater Interfaces ; 15(26): 31393-31402, 2023 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-37339373

RESUMO

Active and nonprecious-metal bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital components of clean energy conversion devices such as regenerative fuel cells and rechargeable metal-air batteries. Porous manganese oxides (MnOx) are promising electrocatalyst candidates because of their high surface area and the abundance of Mn. MnOx catalysts exhibit various oxidation states and crystal structures, which critically affect their electrocatalytic activity. These effects remain elusive mainly because the synthesis of oxidation-state-controlled porous MnOx with similar structural properties is challenging. In this work, four different mesoporous manganese oxides (m-MnOx) were synthesized and used as model catalysts to investigate the effects of local structures and Mn valence states on the activity toward oxygen electrocatalysis. The following activity trends were observed: m-Mn2O3 > m-MnO2 > m-MnO > m-Mn3O4 for the ORR and m-MnO2 > m-Mn2O3 > m-MnO ≈ m-Mn3O4 for the OER. These activity trends suggest that high-valent Mn species (Mn(III) and Mn(IV)) with disordered atomic arrangements induced by nanostructuring significantly influence electrocatalysis. In situ X-ray absorption spectroscopy was used to analyze the changes in the oxidation states under the ORR and OER conditions, which showed the surface phase transformation and generation of active species during electrocatalysis.

19.
Materials (Basel) ; 16(19)2023 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-37834735

RESUMO

This study describes the single-step synthesis of a mesoporous layered nickel-chromium-sulfide (NCS) and its hybridization with single-layered graphene oxide (GO) using a facile, inexpensive chemical method. The conductive GO plays a critical role in improving the physicochemical and electrochemical properties of hybridized NCS/reduced GO (NCSG) materials. The optimized mesoporous nanohybrid NCSG is obtained when hybridized with 20% GO, and this material exhibits a very high specific surface area of 685.84 m2/g compared to 149.37 m2/g for bare NCS, and the pore diameters are 15.81 and 13.85 nm, respectively. The three-fold superior specific capacity of this optimal NCSG (1932 C/g) is demonstrated over NCS (676 C/g) at a current density of 2 A/g. A fabricated hybrid supercapacitor (HSC) reveals a maximum specific capacity of 224 C/g at a 5 A/g current density. The HSC reached an outstanding energy density of 105 Wh/kg with a maximum power density of 11,250 W/kg. A 4% decrement was observed during the cyclic stability study of the HSC over 5000 successive charge-discharge cycles at a 10 A/g current density. These results suggest that the prepared nanohybrid NCSG is an excellent cathode material for gaining a high energy density in an HSC.

20.
Anal Methods ; 15(2): 171-178, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36504026

RESUMO

Surface chemistry of electrodes plays a critical role in the fields of electrochemistry and electric-field-assisted separation. In this study, making ingenious use of the ordered mesoporous structure of silica materials and the electrochemical stability of ionic liquids (ILs) when integrated with polyvinylpyrrolidone (PVP), the PVP-modified IL-mesoporous silica/platinum wire (Pt/PVP@meso-SiO2@IL) was fabricated to increase hydroelectric stability and avoid the problem of electrode polarization. The effect of different amounts of mesoporous silica material used to modify the surface of the Pt electrode was systematically investigated. As a result, we successfully obtained a highly ordered mesoporous Pt/PVP@meso-SiO2 material with smooth surface. Because pentyl triethylamine bis(trifluoromethylsulfonyl) imide exhibits a wide electrochemical window between -3 to 3 V, this IL was chosen to modify mesopores under vacuum. Even after repeatedly applying electric field on Pt/PVP@meso-SiO2@IL 100 times, this working electrode remained stable and showed high hydroelectric stability. After verifying the feasibility of this method, it was successfully applied in the electric-field-assisted separation of 2.0 and 3.0 µm polystyrene particles without any impediment from electrode polarization problems. This work provides a brand-new insight for resolving the problem of electrode polarization by developing a versatile tool for the electroseparation of micro-objects.

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