Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
1.
Magn Reson Med ; 76(6): 1912-1918, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-26762686

RESUMO

PURPOSE: This study suggests a noninvasive and repetitive measurement method using 1 H magnetic resonance spectroscopy to monitor changes in cellular metabolites within a single sample. METHODS: Longitudinal acquisition of cellular metabolites from three-dimensional cultured human osteosarcoma (MG-63) cells was conducted using 3.0 Tesla 1 H MRS for 2 weeks at three time points: days 1, 7, and 14. During the MR spectroscopy (MRS) scan, cell specimen temperatures were kept constant at 37°C by a lab-developed magnetic resonance compatible thermostatic device. A DNA assay and live/dead staining of the cell specimens were carried out at each time point to verify the MRS measurements. RESULTS: Cell viability in the proposed device did not significantly differ from that of cells in a conventional incubator (P = 0.946). Cell proliferation and choline concentration increased during the first week, but remained constant during the second week. Lactate did not change during the first week, but increased during the second week. Likewise, cell viability remained constant until day 7, then decreased. CONCLUSION: The proposed MRS technique results in a survivable environment for longitudinal studies of cells and provides a new way to measure metabolomic changes over time in single specimens of cells. Magn Reson Med 76:1912-1918, 2016. © 2016 International Society for Magnetic Resonance in Medicine.


Assuntos
Algoritmos , Imagem Molecular/instrumentação , Proteínas de Neoplasias/metabolismo , Osteossarcoma/metabolismo , Espectroscopia de Prótons por Ressonância Magnética/instrumentação , Linhagem Celular Tumoral , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Imagem Molecular/métodos , Espectroscopia de Prótons por Ressonância Magnética/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
2.
J Med Ultrason (2001) ; 41(2): 233-7, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27277779

RESUMO

Primary malignancies presenting with multiple distant metastases include lung cancer, gastrointestinal malignancy, breast cancer, and prostatic cancer. Multiple distant metastases from follicular thyroid carcinoma (FTC) are uncommon. Cystic formation in FTC is an atypical finding in ultrasonography. The cystic formation of a thyroid nodule is usually considered a benign sonographic finding. We report the case of a 78-year-old man who presented with multiple distant metastases from an FTC with a predominantly cystic formation.

3.
Artigo em Inglês | MEDLINE | ID: mdl-39374266

RESUMO

The efficient and clean exfoliation of single and/or few-layer nanosheets of WS2, a two-dimensional transition metal dichalcogenides, remains a significant challenge. In this study, a simple exfoliation method was proposed to produce ultrathin WS2 nanosheets by combining the liquid nitrogen exfoliation and nanodispersion techniques. This approach efficiently exfoliated WS2 into several layers of nanosheets via rapid temperature changes and mechanical stress without inducing defects or contamination. After five cycles of heating/liquid nitrogen and nanodispersion, the resulting WS2 nanosheets (WS2-5N ND) were confirmed to have been successfully exfoliated into 1-4 layers. When applied as a promoter in a thermocatalyst for the selective catalytic reduction of NOX using NH3, 2V3WS2/Ti (WS2-5N ND) exhibited excellent NOX conversion and N2 selectivity, along with excellent durability even in the presence of SO2. This result was greater than 2V3WS2/Ti (WS2-5N) subjected to only liquid nitrogen exfoliation, proving the importance of the simultaneous action of both methods. This method is expected to be an important contribution to ongoing research on high-performance WS2-based catalysts, thereby opening up potential opportunities for a wide range of applications.

4.
Materials (Basel) ; 17(14)2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-39063758

RESUMO

We investigated the impact of CaCO3 addition on the density and compressive strength of calcium aluminate cement (CAC)-based cementitious materials in binder jetting additive manufacturing (BJAM). To confirm the formation of a uniform powder bed, we examined the powder flowability and powder bed density for CaCO3 contents ranging from 0 to 20 wt.%. Specifically, powders with avalanche angles between 40.1-45.6° formed a uniform powder bed density with a standard deviation within 1%. Thus, a 3D printing specimen (green body) fabricated via BJAM exhibited dimensional accuracy of less than 1% across the entire plane. Additionally, we measured the hydration characteristics of CAC and the changes in compressive strength over 30 days with the addition of CaCO3. The results indicate that the addition of CaCO3 to CAC-based cementitious materials forms multimodal powders that enhance the density of both the powder bed and the green body. Furthermore, CaCO3 promotes the formation of highly crystalline monocarbonate (C4AcH11) and stable hydrate (C3AH6), effectively inhibiting the conversion of CAC and showing compressive strengths of up to 5.2 MPa. These findings suggest a strong potential for expanding the use of BJAM across various applications, including complex casting molds, cores, catalyst supports, and functional architectural interiors.

5.
Nano Converg ; 9(1): 51, 2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36401645

RESUMO

Vanadium-based catalysts have been used for several decades in ammonia-based selective catalytic reduction (NH3-SCR) processes for reducing NOx emissions from various stationary sources (power plants, chemical plants, incinerators, steel mills, etc.) and mobile sources (large ships, automobiles, etc.). Vanadium-based catalysts containing various vanadium species have a high NOx reduction efficiency at temperatures of 350-400 °C, even if the vanadium species are added in small amounts. However, the strengthening of NOx emission regulations has necessitated the development of catalysts with higher NOx reduction efficiencies. Furthermore, there are several different requirements for the catalysts depending on the target industry and application. In general, the composition of SCR catalyst is determined by the components of the fuel and flue gas for a particular application. It is necessary to optimize the catalyst with regard to the reaction temperature, thermal and chemical durability, shape, and other relevant factors. This review comprehensively analyzes the properties that are required for SCR catalysts in different industries and the development strategies of high-performance and low-temperature vanadium-based catalysts. To analyze the recent research trends, the catalysts employed in power plants, incinerators, as well as cement and steel industries, that emit the highest amount of nitrogen oxides, are presented in detail along with their limitations. The recent developments in catalyst composition, structure, dispersion, and side reaction suppression technology to develop a high-efficiency catalyst are also summarized. As the composition of the vanadium-based catalyst depends mostly on the usage in stationary sources, various promoters and supports that improve the catalyst activity and suppress side reactions, along with the studies on the oxidation state of vanadium, are presented. Furthermore, the research trends related to the nano-dispersion of catalytically active materials using various supports, and controlling the side reactions using the structure of shaped catalysts are summarized. The review concludes with a discussion of the development direction and future prospects for high-efficiency SCR catalysts in different industrial fields.

6.
Nanomaterials (Basel) ; 12(14)2022 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-35889554

RESUMO

Typically, to meet emission regulations, the selective catalytic reduction of NOX with NH3 (NH3-SCR) technology cause NH3 emissions owing to high NH3/NOX ratios to meet emission regulations. In this study, V-Cu/BN-Ti was used to remove residual NOX and NH3. Catalysts were evaluated for selective catalytic oxidation of NH3 (NH3-SCO) in the NH3-SCR reaction at 200-300 °C. The addition of vanadium and copper increased the number of Brønsted and Lewis acid sites available for the reaction by increasing the ratio of V5+ and forming Cu+ species, respectively. Furthermore, h-BN was dispersed in the catalyst to improve the content of vanadium and copper species on the surface. NH3 and NOX conversion were 98% and 91% at 260 °C, respectively. Consequently, slipped NH3 (NH3-Slip) emitted only 2% of the injected ammonia. Under SO2 conditions, based on the NH3 oxidation reaction, catalytic deactivation was improved by addition of h-BN. This study suggests that h-BN is a potential catalyst that can help remove residual NOX and meet NH3 emission regulations when placed at the bottom of the SCR catalyst layer in coal-fired power plants.

7.
Nanomaterials (Basel) ; 11(6)2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-34070897

RESUMO

In this study, we synthesized V2O5-WO3/TiO2 catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts' crystallinity on their acidity, surface species, and catalytic performance through various analysis techniques and a fixed-bed reactor experiment. The isotropic heating method produced crystalline V2O5 and WO3, increasing the availability of both Brønsted and Lewis acid sites, while the one-sided method produced amorphous V2O5 and WO3. The crystalline structure of the two species significantly enhanced NO2 formation, causing more rapid selective catalytic reduction (SCR) reactions and greater catalyst reducibility for NOX decomposition. This improved NOX removal efficiency and N2 selectivity for a wider temperature range of 200 °C-450 °C. Additionally, the synthesized, crystalline catalysts exhibited good resistance to SO2, which is common in industrial flue gases. Through the results reported herein, this study may contribute to future studies on SCR catalysts and other catalyst systems.

8.
BMJ Open ; 10(8): e031181, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32788183

RESUMO

OBJECTIVES: Visceral adipose tissue (VAT) is closely related to obesity complications. We aimed to determine the optimal sex-specific and age-specific VAT thresholds for predicting metabolic complications among individuals living in the United Arab Emirates (UAE). DESIGN: Retrospective cross-sectional study. SETTING: We reviewed medical records of adults who visited a hospital in the UAE. PARTICIPANTS: A total of 369 subjects were included in the final analysis after application of inclusion and exclusion criteria. PRIMARY OUTCOME MEASURES: The prevalence of metabolic syndrome (MES). RESULTS: MES measures excluding waist circumference were present in 73.4% of women and 78.5% of men. VAT areas adjusted for age were significantly greater in the MES group compared with the non-MES group regardless of sex (p<0.05 for all relations); however, subcutaneous adipose tissue areas adjusted for age were not significantly different. Areas under the curve used to predict MES were statistically significant for VAT and visceral to subcutaneous fat ratios among both men and women. Identified cut-off values of VAT to predict MES were 132.0 cm2 in both sexes for individuals under the age of 50 years. For those over 50 years of age, VAT thresholds were greater in women compared with men (173 cm2 vs 124.3 cm2, respectively). CONCLUSIONS: Optimal VAT cut-offs to predict MES were 132 cm2 for individuals under 50 years old living in the UAE. These measures are potential target visceral fat values that could be used to reduce obesity-related morbidity in populations with pre-existing metabolic complications.


Assuntos
Gordura Intra-Abdominal , Tomografia Computadorizada por Raios X , Tecido Adiposo , Adulto , Índice de Massa Corporal , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Emirados Árabes Unidos/epidemiologia
9.
RSC Adv ; 10(28): 16700-16708, 2020 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-35498861

RESUMO

Oxygen functionalized carbon nanotubes synthesized by surface acid treatment were used to improve the dispersion properties of active materials for catalysis. Carbon nanotubes have gained attention as a support for active materials due to their high specific surface areas (400-700 m2 g-1) and chemical stability. However, the lack of surface functionality causes poor dispersion of active materials on carbon nanotube supports. In this study, oxygen functional groups were prepared on the surface of carbon nanotubes as anchoring sites for decoration with catalytic nanoparticles. The oxygen functional groups were prepared through a chemical acid treatment using sulfuric acid and nitric acid, and the amount of functional groups was controlled by the reaction time. Vanadium, tungsten, and titanium oxides as catalytic materials were dispersed using an impregnation method on the synthesized carbon nanotube surfaces. Due to the high density of oxygen functional groups, the catalytic nanoparticles were well dispersed and reduced in size on the surface of the carbon nanotube supports. The selective catalytic reduction catalyst with the oxygen functionalized carbon nanotube support exhibited enhanced NO x removal efficiency of over 90% at 350-380 °C which is the general operating temperature range of catalysis in power plants.

10.
Environ Sci Pollut Res Int ; 26(36): 36107-36116, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30835067

RESUMO

This research is conducted to improve the dispersion of MnOx-CeO2 catalyst because manganese is easily aggregated during continuous thermal environment at operating temperature. Aggregated MnOx particles on the support can be a major reason to degrade the catalyst performance. Therefore, the improved dispersion of MnOx particles leads to the enhancement of the catalyst performance by utilizing hexagonal boron nitride (h-BN) which is well known as thermally stable material. Due to the dispersion of MnOx-CeO2 with 5-20 nm particle size, h-BN-supported MnOx-CeO2 catalyst shows the 93% efficiency in NOx removal at 200 °C. The structure and properties of MnOx-CeO2/h-BN catalyst are characterized by X-ray diffraction, Fourier transform infrared spectroscopy spectra, and NH3-temperature programmed desorption. Then, NOx removal efficiency of catalyst is evaluated on a fixed bed reactor and h-BN-supported catalyst, (Mn0.2-Ce0.1)/BN, increases NOx removal efficiency up to 20% at 200 °C in spite of 2/3 reduced content of MnOx-CeO2 compared to no-supported catalyst (Mn0.3-Ce0.15).


Assuntos
Poluentes Atmosféricos/análise , Compostos de Boro/química , Cério/química , Compostos de Manganês/química , Nanopartículas/química , Óxidos de Nitrogênio/análise , Óxidos/química , Poluição do Ar/prevenção & controle , Catálise , Modelos Teóricos , Oxirredução , Temperatura , Difração de Raios X
11.
J Nanosci Nanotechnol ; 15(11): 9083-7, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26726647

RESUMO

Graphene has many excellent properties such as wide specific surface area, outstanding electrical mobility, and high optical transmittance. Due to these advantages, which make graphene appropriate matrix supporting vanadium for the nanocomposite. Also, depending on the synthesis process, graphene can be obtainable graphene oxide (GO) and reduced graphene oxide (RGO). Moreover, RGO has been receiving increased attention due to its nature to easily reduced to graphene, referred to as RGO, which has wide application. The purpose of this study is to investigate the characteristic of V2O5 deposited on RGO. The nanocomposite of vanadium oxide (V2O5) supported on RGO was prepared by different methods of evaporation, impregnation and impregnation with dispersant. XRD, SEM, TEM, BET and TGA analyses were used to investigate their chemical stability, and amount in vanadium oxide on RGO. This synthesis of V2O5 supported RGO is expected to be used as selective catalytic reduction (SCR) catalyst for De-NOx.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA