Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
ACS Appl Mater Interfaces ; 15(4): 5071-5085, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36656149

RESUMO

Donor-doped TiO2-based materials are promising thermoelectrics (TEs) due to their low cost and high stability at elevated temperatures. Herein, high-performance Nb-doped TiO2 thick films are fabricated by facile and scalable screen-printing techniques. Enhanced TE performance has been achieved by forming high-density crystallographic shear (CS) structures. All films exhibit the same matrix rutile structure but contain different nano-sized defect structures. Typically, in films with low Nb content, high concentrations of oxygen-deficient {121} CS planes are formed, while in films with high Nb content, a high density of twin boundaries are found. Through the use of strongly reducing atmospheres, a novel Al-segregated {210} CS structure is formed in films with higher Nb content. By advanced aberration-corrected scanning transmission electron microscopy techniques, we reveal the nature of the {210} CS structure at the nano-scale. These CS structures contain abundant oxygen vacancies and are believed to enable energy-filtering effects, leading to simultaneous enhancement of both the electrical conductivity and Seebeck coefficients. The optimized films exhibit a maximum power factor of 4.3 × 10-4 W m-1 K-2 at 673 K, the highest value for TiO2-based TE films at elevated temperatures. Our modulation strategy based on microstructure modification provides a novel route for atomic-level defect engineering which should guide the development of other TE materials.

2.
Gels ; 8(11)2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36421560

RESUMO

This study aimed to determine the effect of different mixing rates and the addition of lecithin on the rheological mechanical, and acoustic properties of agar gels with the addition of canola oil. The mixing rate of the agar-oil mixture was changed from 10,000 to 13,000 rpm. Additionally, agar gels with the addition of lecithin from 1 to 5% were prepared. The frequency sweep test was used (at 4 and 50 °C) within the linear viscoelastic region (LVR) in oscillatory measurement. The agar-oil mixture was cooled from 80 to 10 °C, enabling the obtainment of the gelling temperature. Texture profile analysis (TPA) and compression tests, as well as the acoustic emission method, were applied to analyse the texture of the gels. The syneresis and stability of gels during storage were also measure. The increase in mixing rate in the case of agar gel with canola oil causes an increase in the elastic component of materials as well hardness and gumminess. Also, samples prepared with the higher mixing rate have more uniform and stable structures, with small bubbles. The increase in the concentration of lecithin is ineffective due to the formation of gels with a weak matrix and low hardness, gumminess, and stability during storage.

3.
Foods ; 11(16)2022 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-36010407

RESUMO

The aim of this study was to investigate the effect of application of pulsed electric field (PEF) and different freezing methods (fast, slow and vacuum freezing) on the drying kinetics as well as selected physical properties of freeze-dried apple. The apples were subjected to PEF treatment with range of pulses from 0 to 160 and the intake energy from 0 to 1327 kJ·g-1. Apples with and without PEF treatment were frozen with different rates and the freeze-dried. The water content, water activity and colour attributes of freeze-dried apples were investigated. Regression analysis and fitting procedures showed that among six different models, the Midilli et al. model the best described the drying curves of all dried samples. The highest value of the parameter L* = 71.54 was obtained for freeze-dried sample prepared without PEF pre-treatment and fast frozen. Application of PEF pre-treatment resulted in increase in browning index of freeze-dried apples (BI). The studies confirmed the positive effect of PEF on the freeze drying rate only in the case of the slow or fast freezing of the material after the application of low-energy PEF treatment. However, the increase in drying rate was also observed after application of slow and vacuum freezing of the material without PEF pre-treatment. These technologies can be recommended for optimization of the freeze drying process of apples. The statement that the freeze drying process with application of appropriately selected PEF processing parameters causing only partial destruction of cell membranes can be considered as an innovative contribution to the development of science about the possibilities of PEF application.

4.
Gels ; 8(2)2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35200491

RESUMO

This study aimed to determine the effect of the addition of apple juice concentrate (AJC) on the properties of agar gel and dried materials. Agar gels with the addition of apple juice concentrate in the range of 5-20% were prepared with or without the addition of maltodextrin. The gels were also soaked in the solution of AJC. The water content, water activity, densities, some mechanical and acoustic descriptors of gels, and the freeze-dried gels were analysed. The porosity and shrinkage of dried products were also investigated. The addition of AJC significantly changed mechanical and acoustic properties of gels. The hardness of gels decreased with a higher addition of concentrate. Dried samples with a lower concentration of sugars (the lower addition of AJC) were characterised by lower shrinkage and higher porosity, as well as crispness and glass transition temperature. The investigated mechanical and acoustic properties of dried gels showed the addition of apple concentrate at the level of 5% to agar solution was optimal.

5.
Gels ; 7(3)2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34563023

RESUMO

This study aimed to determine the effect of the addition of chokeberry juice concentrate (CJC) and foaming agent (egg albumin) with different percentages on the selected physical properties of agar gel. The agar gels with the addition of 5, 10, and 20% concentrations of chokeberry juice concentrate and with fructose addition were prepared. In addition, the foamed gels with different concentrations of egg albumin (in the range 0.5-2.0%) and CJC were produced. The water content, colour, density, hold-up and some mechanical and TPA (Texture Profile Analysis) descriptors as well some structural and acoustic emission parameters of non-aerated and foamed gels were analysed. The addition of CJC changed the colour of agar gel with fructose, the attractive appearance of the aerated gel was also linked with the addition of concentrate. The addition of 20% of CJC and foaming agent created samples with very low hardness, cohesiveness, and gumminess, and the structure of the aerated samples was characterised by the larger bubble diameter and the wider distribution of their size. The more promising texture and structure properties were obtained for samples with aerated gels with 5 and 10% addition of chokeberry juice concentrate.

6.
Sci Rep ; 10(1): 19103, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33127946

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

7.
Foods ; 9(10)2020 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-33080983

RESUMO

Freeze-drying, also known as lyophilization, is a process in which water in the form of ice under low pressure is removed from a material by sublimation. This process has found many applications for the production of high quality food and pharmaceuticals. The main steps of the freeze-drying process, such as the freezing of the product and primary and secondary drying, are described in this paper. The problems and mechanisms of each step of the freeze-drying process are also analyzed. The methods necessary for the selection of the primary and secondary end processes are characterized. The review contains a description of the effects of process conditions and the selected physical properties of freeze-dried materials, such as structural properties (shrinkage and density porosity), color, and texture. The study shows that little attention is given to the mechanical properties and texture of freeze-dried materials obtained from different conditions of the lyophilization process.

8.
Sci Rep ; 10(1): 11539, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32686707

RESUMO

We have created a new architected material, which is both highly deformable and ultra-resistant to dynamic point loads. The bio-inspired metallic cellular structure (with an internal grid of large ceramic segments) is non-cuttable by an angle grinder and a power drill, and it has only 15% steel density. Our architecture derives its extreme hardness from the local resonance between the embedded ceramics in a flexible cellular matrix and the attacking tool, which produces high-frequency vibrations at the interface. The incomplete consolidation of the ceramic grains during the manufacturing also promoted fragmentation of the ceramic spheres into micron-size particulate matter, which provided an abrasive interface with increasing resistance at higher loading rates. The contrast between the ceramic segments and cellular material was also effective against a waterjet cutter because the convex geometry of the ceramic spheres widened the waterjet and reduced its velocity by two orders of magnitude. Shifting the design paradigm from static resistance to dynamic interactions between the material phases and the applied load could inspire novel, metamorphic materials with pre-programmed mechanisms across different length scales.

9.
Foods ; 8(4)2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30987379

RESUMO

Methods of testing and describing the recrystallization process in ice cream systems were characterized. The scope of this study included a description of the recrystallization process and a description and comparison of the following methods: microscopy and image analysis, focused beam reflectance measurement (FBRM), oscillation thermo-rheometry (OTR), nuclear magnetic resonance (NMR), splat-cooling assay, and X-ray microtomography (micro-CT). All the methods presented were suitable for characterization of the recrystallization process, although they provide different types of information, and they should be individually matched to the characteristics of the tested product.

10.
Hepatogastroenterology ; 57(101): 787-93, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21033230

RESUMO

BACKGROUND/AIMS: Inflammatory bowel disease (IBD) represents the heterogeneous group of disorders with a wide variety of clinical manifestations. The Montreal classification has been developed recently and its accuracy in categorizing of IBD phenotypes needs to be investigated. The aim of the study was to assess the usefulness of the Montreal classification compared to CAI and CDAI in various disease activity, serological and clinical manifestations of IBD. METHODOLOGY: The study was performed in 125 IBD patients: 71 patients with ulcerative colitis, 31 with Crohn's disease and 23 with IBD unclassified (indeterminate colitis). Disease activity and clinical course were assessed using Montreal classification, Clinical Activity Index and Crohn's Disease Activity Index. pANCA and ASCA were measured with ELISA, using widely used, commercial antibody panel (Cogent Diagnostics and Genesis Diagnostics and MedTek kits). RESULTS: No significant correlation has been found between pANCA/ASCA presence and disease activity using CAI and CDAI. ASCA and pANCA-/ASCA+ antibodies pattern had been detected more often in patients with Crohn's disease after surgery, with localization in small or small and large intestine, without perianal lesions and with early disease onset. CONCLUSIONS: Correlations between serotype and certain clinical phenotype are present, which could potentially be of value in the classification of patients particular treatment regimen. We have noticed that clinical course assessment using Montreal classification shows precisely real CD patients state.


Assuntos
Doenças Inflamatórias Intestinais/classificação , Índice de Gravidade de Doença , Adulto , Idoso , Anticorpos/análise , Anticorpos Anticitoplasma de Neutrófilos/análise , Índice de Massa Corporal , Colite Ulcerativa/classificação , Doença de Crohn/classificação , Feminino , Humanos , Doenças Inflamatórias Intestinais/imunologia , Masculino , Pessoa de Meia-Idade , Fenótipo , Saccharomyces cerevisiae/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...