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1.
Food Chem ; 303: 125344, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31446363

RESUMO

The effect of annealing on structure and physicochemical properties of four different waxy starches were investigated to understand the mechanism of annealing in the absence of amylose. Granule morphology, X-ray pattern, molecular order, and gelatinization enthalpy remained unchanged upon annealing. Relative crystallinity of waxy corn starch increased from 42.4 to 46.1% on annealing, while it remained unchanged in other starches. Annealing increased the gelatinization temperatures, while it decreased the temperature range. Waxy potato starch showed the highest increase in To, where it was 8.1 °C after 72 h of annealing. Viscosity profiles were only slightly affected by the annealing treatment. Susceptibility towards amylolysis increased in waxy corn and waxy barley, while it decreased in waxy potato and waxy rice. This study demonstrated that even in the absence of amylose, annealing caused changes in the structure and properties, however, the extents of these changes varied depending on the botanical origin.


Assuntos
Fenômenos Químicos , Amido/química , Ceras/química , Amilopectina/química , Amilose/química , Oryza/química , Solanum tuberosum/química , Temperatura Ambiente , Viscosidade , Zea mays/química
2.
Food Chem ; 302: 125267, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31400701

RESUMO

A study was to determine the correlation between the fine structure and the physicochemical properties of pre-gelatinized corn starch (PGCS) and the quality of noodles with added PGCS. Drum-dried corn starch (DDCS) and extrusion-cooked corn starch (ECCS) were used. The results revealed that the cold-water viscosity of ECCS and DDCS was about 10 and 100 times greater, respectively, than that of native corn starch (NCS), and the gel strength of DDCS was 1.67 times greater than that of ECCS. The average hydrodynamic radius of whole molecular (R¯h) and Ap were approximately half that of native corn starch in ECCS. Dough sheets prepared with various concentrations of PGCS (5-10%, w/w) had significantly greater tensile strength, and the addition of PGCS significantly increased the smoothness of the cooked noodles. DDCS was better than ECCS for increasing the noodles' processing quality.


Assuntos
Culinária , Qualidade dos Alimentos , Gelatina/química , Amido/química , Farinha/análise , Viscosidade , Água/química
3.
Food Chem ; 302: 125141, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31416000

RESUMO

Four jams were made using two wild species of Physalis spp., two containing seeds (P1WS and P2WS) and two without seeds (P1WHS and P2WHS). Physicochemical, nutraceutical and rheological properties of the jams were determined and a sensory evaluation made. P1WS and P2WS jams had lower carbohydrates contents, reducing sugars and calories, and higher fiber contents than P1WHS and P2WHS. The presence of seeds in the jams increased phenols and flavonoids. However, the seedless jams had better sensory acceptance. The dynamic rheological testing indicated a gel-like behavior (G'>G'') in whole jams. Also, shearing flow testing showed shear-thinning and thixotropic behaviors, which are shared characteristics with others fruit jams, such as mango or gabiroba. The presence of seeds in the jam affected directly yield stress, apparent viscosity, hysteresis area, and viscoelastic parameters, which were described in the sensory analysis as a "less desirable texture". The use of seeds from wild species of Physalis spp., increased the nutritional value of jam. However, it would be necessary to improve consumer acceptance through technological processes prior to marketing.


Assuntos
Suplementos Nutricionais/análise , Manipulação de Alimentos , Frutas/química , Physalis/química , Reologia , Sementes/química , Paladar , Fibras na Dieta/análise , Flavonoides/análise , Valor Nutritivo , Fenóis/análise , Viscosidade
4.
J Contemp Dent Pract ; 20(7): 822-827, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31597802

RESUMO

AIM: The aim of this study is to evaluate the effect of multilayering incremental technique on the microleakage of high-viscosity bulk-fill composite restorations in endodontically treated teeth. MATERIALS AND METHODS: A total of 60 human mandibular premolar teeth were divided into four groups after standardized access preparation with a protaper technique followed by single-cone obturation to receive the following restorations for the access preparations. Group I (n = 20): bulk-fill composite (Filtek™ Bulk fill) using a bulk technique, group II (n = 20): bulk-fill composite (Filtek™ Bulk fill) using an incremental layering technique, group III (negative control) (n = 10): gutta-percha was kept intact at the access orifice and covered with a nail polish, and group IV (positive control) (n = 10): gutta-percha was kept intact at the orifice. The samples were thermocycled at 5°C and 55°C for 500 cycles followed by dye penetration with 2% methylene blue and then the scoring was done under a stereomicroscope at 10× magnification. The data so obtained were compared for microleakage using a Chi-square test. There was a significant difference among all the groups except groups II and III. RESULTS: Bulk-fill composites used with an incremental layering technique sealed significantly better than the other groups followed by bulk-fill composite in the bulk technique. CONCLUSION: Within the limitations of the present study, it can be concluded that the incremental layering technique with bulk-fill composites significantly decreases microleakage in the restored access preparations of endodontically treated teeth.


Assuntos
Infiltração Dentária , Dente não Vital , Resinas Compostas , Preparo da Cavidade Dentária , Restauração Dentária Permanente , Humanos , Viscosidade
5.
J Chem Phys ; 151(12): 124104, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31575184

RESUMO

An interfacial regularized Stokeslet scheme is presented to predict the motion of solid bodies (e.g., proteins or gel-phase domains) embedded within flowing lipid bilayer membranes. The approach provides a numerical route to calculate velocities and angular velocities in complex flow fields that are not amenable to simple Faxén-like approximations. Additionally, when applied to shearing motions, the calculations yield predictions for the effective surface viscosity of dilute rigid-body-laden membranes. In the case of cylindrical proteins, effective viscosity calculations are compared to two prior analytical predictions from the literature. Effective viscosity predictions for a dilute suspension of rod-shaped objects in the membrane are also presented.


Assuntos
Bicamadas Lipídicas/química , Modelos Químicos , Fenômenos Biomecânicos , Proteínas de Membrana/química , Torque , Viscosidade
6.
Braz Dent J ; 30(5): 476-483, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596332

RESUMO

The aim of this study was to evaluate the bond strength, bottom/top hardness ratio, marginal adaptation, and interfacial nanoleakage of regular viscosity bulk fill composites (RVBFC) and regular viscosity traditional composites (RVTC). Two RVBFC (Filtek Bulk Fill and Aura Bulk Fill) and two RVTC (Filtek Z250XT and Aura) were assessed. Forty conical cavities (4.8×2.8×4.0) were prepared in bovine dentin and restored with composites (n=10). After 24h in water, marginal adaptation was evaluated by staining with a caries detector. The top and bottom surfaces of the conical restorations were stained for five seconds and the gap percentage in the composite/dentin interface was determined using digital images on a measurement program (ImageTool). The Vickers microhardness was measured and the bottom/top microhardness ratio (B/T) was determined. Push-out bond strength test was performed in a universal testing machine (0.5mm/min) and failure modes were evaluated in a stereomicroscope (20×). Other specimens (n=3) were produced for interfacial nanoleakage evaluation. Data were analyzed using one and two-way ANOVA and Tukey's test (α=0.05). The gap percentage was higher in the bottom compared to the top. The B/T ratio of the Aura Bulk Fill was statistically lower than other composites. Push-out bond strength were similar among composites. The RVBFC presented lower nanoleakage than the RVTC in the bottom of the conical restoration and there was no difference among the materials in the top surfaces. In conclusion, Filtek Bulk Fill performed better than Aura Bulk Fill regarding the analyzed properties.


Assuntos
Resinas Compostas , Cárie Dentária , Animais , Bovinos , Dentina , Dureza , Teste de Materiais , Viscosidade
7.
J Agric Food Chem ; 67(40): 11198-11209, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31532988

RESUMO

The importance of inhibition sensitivity for xylanase functionality in bread making was investigated using mutants of the wild-type Bacillus subtilis xylanase (XBSTAXI), sensitive to Triticum aestivum xylanase inhibitor (TAXI). XBSNI, a mutant with reduced sensitivity to TAXI, and XBSTI, a mutant sensitive to all wheat endogenous proteinaceous inhibitors (TAXI, Xylanase Inhibiting Protein and Thaumatin-like Xylanase Inhibitor) were used. The higher inhibition sensitivity of XBSTAXI and XBSTI compared to XBSNI was associated with a respective 7- and 53-fold increase in enzyme dosage required for a maximal increase in bread loaf volume. XBSTI and XBSTAXI were only active during the mixing phase and the beginning of fermentation, while XBSNI was able to hydrolyze arabinoxylan until the end of fermentation. In spite of this difference in activity profile, no differences in loaf volume were observed for the different xylanases at optimal concentrations. Dough extensional viscosity analysis suggests that increased water availability as a result of xylanase activity favors starch-starch and starch-gluten interactions and drives the improvement in bread loaf volume.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Pão/análise , Endo-1,4-beta-Xilanases/antagonistas & inibidores , Endo-1,4-beta-Xilanases/química , Inibidores Enzimáticos/química , Proteínas de Plantas/química , Bacillus subtilis/química , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Inibidores Enzimáticos/metabolismo , Farinha/análise , Manipulação de Alimentos , Hidrólise , Mutação , Proteínas de Plantas/metabolismo , Triticum/química , Triticum/metabolismo , Viscosidade
8.
Int J Nanomedicine ; 14: 6439-6450, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31496696

RESUMO

Background and purpose: The essential oil derived from clove buds (Syzygium aromaticum) has been used as a chemopreventive agent in Ayurvedic medicine. The antiviral, antibacterial, and anticancer properties of its chemo-skeleton have motivated this study to explore its efficacy in pharmaceutics. Methods: Nanoscale-based emulsions were prepared by employing a spontaneous emulsification technique through self-assembly using varying concentrations of Tween 20 and Tween 80 surfactants. Their physicochemical properties and stability were studied in order to choose an optimum formulation which was clear and stable. The cytotoxicity of the stable oil-based emulsion system was evaluated using MTT assay, colony formation assay, and Annexin V-FITC assay against the thyroid cancer cell line (HTh-7). Results: All three methods verified apoptosis and reduction in cancer cell proliferation, making the formulation a promising candidate as an alternative cancer drug. The oil-based emulsion system was also tested for its antibacterial properties against Staphylococcus aureus. Membrane permeability studies proved its efficacy to permeate through cell membrane, thereby increasing the leakage of cytoplasmic contents. Conclusion: Many current treatments for cancers are aggressive yet ineffective. This study positions the clove bud-based nanoscale emulsion as a suitable candidate for further in vivo studies and trials as a cancer drug.


Assuntos
Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Óleos Voláteis/farmacologia , Syzygium/química , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Composição de Medicamentos , Emulsões , Humanos , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Óleos Voláteis/química , Staphylococcus aureus/efeitos dos fármacos , Tensoativos/química , Viscosidade
9.
Soft Matter ; 15(33): 6660-6676, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31389467

RESUMO

The dynamic behavior of monoclonal antibodies (mAbs) at high concentration provides insight into protein microstructure and protein-protein interactions (PPI) that influence solution viscosity and protein stability. At high concentration, interpretation of the collective-diffusion coefficient Dc, as determined by dynamic light scattering (DLS), is highly challenging given the complex hydrodynamics and PPI at close spacings. In contrast, self-diffusion of a tracer particle by Brownian motion is simpler to understand. Herein, we develop fluorescence correlation spectroscopy (FCS) for the measurement of the long-time self-diffusion of mAb2 over a wide range of concentrations and viscosities in multiple co-solute formulations with varying PPI. The normalized self-diffusion coefficient D0/Ds (equal to the microscopic relative viscosity ηeff/η0) was found to be smaller than η/η0. Smaller ratios of the microscopic to macroscopic viscosity (ηeff/η) are attributed to a combination of weaker PPI and less self-association. The interaction parameters extracted from fits of D0/Ds with a length scale dependent viscosity model agree with previous measurements of PPI by SLS and SAXS. Trends in the degree of self-association, estimated from ηeff/η with a microviscosity model, are consistent with oligomer sizes measured by SLS. Finally, measurements of collective diffusion and osmotic compressibility were combined with FCS data to demonstrate that the changes in self-diffusion between formulations are due primarily to changes in the protein-protein friction in these systems, and not to protein-solvent friction. Thus, FCS is a robust and accessible technique for measuring mAb self-diffusion, and, by extension, microviscosity, PPI and self-association that govern mAb solution dynamics.


Assuntos
Anticorpos Monoclonais/química , Fenômenos Biofísicos , Difusão , Fluorescência , Corantes Fluorescentes/química , Microscopia de Fluorescência , Modelos Químicos , Multimerização Proteica , Estabilidade Proteica , Soluções , Viscosidade
10.
Soft Matter ; 15(33): 6630-6641, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31403143

RESUMO

The mechanics of blister delamination and growth plays a major role in a diversity of areas including medicine (skin pathology and mechanics of cell membranes), materials (adhesive and fracture) or soft robotics (actuation and morphing). The behavior of a blister in this context is typically difficult to grasp as it arises from the interplay of two highly nonlinear and time-dependent processes: membrane attachment and decohesion from a substrate. In the present work, we device a simplified approach, based on experimental systems, to predict the deformation path of a blister under various conditions. For this, we consider the problem of a growing blister made of a rubber-like membrane adhered on a rigid substrate, and develop a theoretical and experimental framework to study its stability and growth. We start by constructing a theoretical model of viscoelastic blister growth which we later validate with an experimental setup. We show that blister growth is controlled by the competition between two instabilities: one inherent to the rubber, and a second one pertaining to the adhesion with the substrate. Using these concepts, we show that a "targeted" stable blister shape can be achieved by controlling two parameters: the thickness of the film and the inflation rate.


Assuntos
Simulação por Computador , Membranas Artificiais , Modelos Teóricos , Adsorção , Elasticidade , Cinética , Propriedades de Superfície , Termodinâmica , Viscosidade
11.
Food Chem ; 301: 125230, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31374531

RESUMO

Zeaxanthin nanoparticles (Zea-NP) and zeaxanthin nanoemulsion (Zea-NE) were incorporated in yogurt. Control yogurt (CY), yogurt added of nanoparticles (Y-NP) and yogurt added of nanoemulsion (Y-NE) were evaluated weekly regarding pH, titratable acidity, color, textural parameters, viscosity and syneresis during 28 days. Zeaxanthin retention in Y-NP and Y-NE was also determined over storage. Sensory attributes and morphology were evaluated in all yogurt samples, and zeaxanthin bioaccessibility after in vitro digestion was analyzed in Y-NP and Y-NE after preparation. At the end of storage time, zeaxanthin retention was higher in Y-NP (22.31 ±â€¯2.53%) than in Y-NE (16.84 ±â€¯0.53%). Despite the lower firmness and viscosity observed in Y-NP, these changes were not sensory perceived. The bioaccessibility after in vitro digestion suggested that nanoencapsulation provided a controlled release of the carotenoid. Zea-NP can be incorporated in yogurt, allowing the dispersion of a hydrophobic compound in a hydrophilic matrix, providing stability.


Assuntos
Carotenoides/química , Fenômenos Químicos , Nanopartículas/química , Paladar , Iogurte/análise , Zeaxantinas/química , Viscosidade
12.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(4): 613-618, 2019 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-31441262

RESUMO

Study of the mechanical properties of in vivo corneal materials is an important basis for further study of corneal physiological and pathological phenomena by means of finite element method. In this paper, the elastic coefficient ( E) and viscous coefficient ( η) of normal cornea and keratoconus under pulse pressure are calculated by using standard linear solid model with the data provided by corneal visualization scheimpflug technology. The results showed that there was a significant difference of E and η between normal cornea and keratoconus cornea ( P < 0.05). Receiver operating characteristic curve analysis showed that the area under curve (AUC) for E, η and their combined indicators were 0.776, 0.895 and 0.948, respectively, which indicated that keratoconus could be predicted by E and η. The results of this study may provide a reference for the early diagnosis of keratoconus and avoid the occurrence of keratoconus after operation, so it has a certain clinical value.


Assuntos
Córnea/fisiologia , Elasticidade , Ceratocone/patologia , Viscosidade , Área Sob a Curva , Humanos , Curva ROC
13.
Biophys Chem ; 252: 106223, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31325894

RESUMO

Simulations of electron paramagnetic resonance spectra of stearic acid spin labels in lipid bilayers are used to illustrate the fact that the apparent order parameter Sapp calculated from the spectral shape does not coincide with the true order parameter S in the case of slow motions. While S reflects a static property as the degree of order of the lipid chains, Sapp depends on both order and dynamics. Thus, calibration procedures intended to obtain bilayer microviscosity values from Sapp in the slow motion regime are not reliable. However, Sapp is a useful tool to describe trends in membrane fluidity.


Assuntos
Bicamadas Lipídicas/química , Ácidos Esteáricos/química , Espectroscopia de Ressonância de Spin Eletrônica , Estrutura Molecular , Marcadores de Spin , Viscosidade
14.
Food Chem ; 300: 125225, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31351257

RESUMO

This study was intended to produce turanose and resistant starch (RS) using recombinant amylosucrase from Neisseria subflava (NsAS). Turanose production yield maximally reached to 76% of sucrose substrate at 40 °C by NsAS treatment. To evaluate turanose as a low-calorie functional sweetener, its hydrolysis pattern was investigated in continuous artificial digestion system. When turanose was consecutively exposed through small intestinal phase, only 8% of disaccharide was hydrolyzed. Structural modification of gelatinized corn or rice starch was carried out by NsAS with sucrose as a glucosyl donor. Non-digestibility of enzyme-modified starches increased to 47.3% maximally through branch-chain elongation, enough for chain-chain association and recrystallization. Obviously, NsAS-modified starches had higher gelatinization peak temperatures than native counterparts, and their paste viscosity was inversely related to their digestibility due to elongated-chain induced retrogradation. These results suggested that NsAS could be a vital biocatalyst candidate in food industry to produce next generation low-calorie carbohydrate food materials.


Assuntos
Dissacarídeos/metabolismo , Glucosiltransferases/metabolismo , Neisseria/enzimologia , Amido/metabolismo , Digestão , Glucosiltransferases/genética , Hidrólise , Oryza/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Amido/química , Sacarose/química , Sacarose/metabolismo , Edulcorantes/metabolismo , Viscosidade , Zea mays/química
15.
Soft Matter ; 15(30): 6160-6170, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31317157

RESUMO

We investigate by time-resolved synchrotron ultra-small X-ray scattering the dynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions following a temperature quench. Samples at a fixed concentration (237 mg ml-1) but with different protein compositions are investigated. In our experimental conditions, we show that fluid viscoelastic samples depleted in polymeric glutenin phase-separate following a spinodal decomposition process. We quantitatively probe the late stage coarsening that results from a competition between thermodynamics that speeds up the coarsening rate as the quench depth increases and transport that slows down the rate. For even deeper quenches, the even higher viscoelasticity of the continuous phase leads to a "quasi" arrested phase separation. Anomalous phase-separation dynamics is by contrast measured for a gel sample rich in glutenin, due to elastic constraints. This work illustrates the role of viscoelasticity in the dynamics of LLPS in protein dispersions.


Assuntos
Fracionamento Químico/métodos , Glutens/isolamento & purificação , Viscosidade , Glutens/química , Espalhamento de Radiação , Síncrotrons , Temperatura Ambiente
16.
Food Chem ; 299: 125129, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31299518

RESUMO

Three varieties of sweetpotato flour (Orange Sunset (OS), Purple Dawn (PD), and Red) were treated by high hydrostatic pressure (HHP). Thermal analysis showed that complete starch gelatinization occurred in PD and Red subjected to 600 MPa. Starch of OS was partially gelatinized at 600 MPa. The pressure of 600 MPa caused significant decreases in peak viscosity, breakdown and setback, and an increase in pasting temperature. Compared with native samples, HHP-treated samples showed higher in vitro starch digestibility in uncooked conditions but lower digestibility in cooked conditions. HHP significantly improved the extractability of bioactive compounds from sweetpotato flour. The changes in ß-carotene content, total phenolic content, in vitro antioxidant activities, individual phenolic acids, and anthocyanins profiles were investigated. This study suggests the potential of HHP as a non-thermal processing tool to modify the functional properties of sweetpotato flour.


Assuntos
Farinha , Ipomoea batatas/química , Farinha/análise , Indústria de Processamento de Alimentos/métodos , Gelatina/química , Pressão Hidrostática , Hidroxibenzoatos/análise , Especificidade da Espécie , Amido/química , Temperatura Ambiente , Viscosidade , beta Caroteno/análise
17.
Food Chem ; 299: 125133, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31323441

RESUMO

The aim of this study was to investigate the effect of NaCl on the formation, structure and property of samples formed from wheat starch (WS) and the fatty acids (lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA)). Results from RVA, DSC, XRD and Raman analyses showed that LA, and to a lesser extent MA, formed complexes with WS. Under the experimental conditions used, only minor amounts of WS-PA and WS-SA complexes formed. The low solubility of PA and SA, and to some extent MA, in water caused these fatty acids to mostly self-aggregate. The presence of NaCl promoted the formation of WS-LA complexes and, to a lesser extent complexes with MA, but had little effect on the formation of WS-PA and WS-SA complexes. Solubility of fatty acids in aqueous medium was proposed to be a major factor for the formation of starch-fatty acid complexes.


Assuntos
Ácidos Graxos/química , Lipídeos/química , Cloreto de Sódio/química , Amido/química , Triticum/química , Varredura Diferencial de Calorimetria , Solubilidade , Análise Espectral Raman , Viscosidade , Difração de Raios X
18.
Food Chem ; 300: 125191, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31352290

RESUMO

Viscosity is a property that exerts great influence on the body of wines, since it affects the sensation of thickness in the mouth. The present study refers to the quantitative correlation of the major components of wine, alcohol, reduced sugar, glycerol and total acidity, in its viscosity. Various model aqueous solutions consisting of these components were prepared and viscosity was measured at 20 °C. Each component was studied either alone or in mixtures with the others. Viscosity of white dry wines samples was also measured. From the experimental results, linear multi-dependence equations were derived, which correlate the viscosity with the concentration of the components of the solutions, each of them alone and in combination. Glucose was found to affect viscosity of model aqueous solutions the most, whereas ethanol had the least effect. The knowledge of these factors may have a practical value in optimizing wine's body.


Assuntos
Etanol/química , Glucose/química , Glicerol/química , Tartaratos/química , Vinho , Modelos Químicos , Soluções/química , Viscosidade , Água , Vinho/análise
19.
Comput Methods Biomech Biomed Engin ; 22(13): 1093-1102, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31268350

RESUMO

Osteoporosis (OP) is common with advancing age. Several studies have shown a strong correlation between OP and otosclerosis. However, no studies have investigated OP of the malleus, incus or stapes in the human middle ear, its effect on middle ear transfer function. Here, we investigate whether these three ossicles develop OP, and how this affects middle ear transfer function. The effect of OP on middle ear transfer function was investigated in simulations based on a finite element (FE) method. First, the FE model used in our previous study was refined, and optimized by introducing viscoelastic properties to selected soft tissues of the middle ear. Then, the FE model was used to simulate OP of the three ossicles and assess its influence on middle ear transfer function. Other possible age-related changes, such as stiffness of the joints or ligaments in the middle ear, were also investigated. The results indicated that OP of the ossicles could increase the high frequency displacement of both the umbo and stapes footplate (FP). However, the stiffness of the middle ear soft tissue can lead to the decrease of middle ear gain at lower frequencies. Furthermore, loosening of these joints or ligaments could increase displacement of the umbo and stapes FP. In conclusion, although age-related hearing loss is most commonly conceived of as sensorineural hearing loss (SNHL), we found that age-related changes may also include OP and changes in joint stiffness, but these will have little effect on middle ear transfer function in elderly people.


Assuntos
Envelhecimento/fisiologia , Orelha Média/fisiologia , Idoso , Simulação por Computador , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Ligamentos/fisiologia , Osteoporose/fisiopatologia , Estribo/fisiologia , Viscosidade
20.
Food Chem ; 300: 125193, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31326675

RESUMO

Tartary buckwheat grains were subjected to hydrothermal treatments (steaming/boiling/autoclaving) whose effects on rutin enrichment in the buckwheat flour by rutin migration from the bran fraction were investigated in terms of optical, rheological, thermal, and microstructural properties. The highest amount of rutin was observed in the bran out of the native milling fractions (hull, bran, and flour). The hydrothermal treatments however increased the level of rutin in the flour, even showing a higher level of rutin than the bran in the autoclaved sample. Furthermore, rutin in the hydrothermally-treated flours was not degraded into quercetin by mixing with water. Scanning electron microscopic images demonstrated that the granules of buckwheat starch round in shape and grouped in lumps were disrupted by the hydrothermal treatments. The rutin contents of the buckwheat flour samples were linearly well-correlated with their pasting profiles (peak viscosity), colors (L and b values), and thermal parameters (gelatinization enthalpy and temperature).


Assuntos
Fagopyrum/química , Farinha/análise , Alimentos Fortificados , Indústria de Processamento de Alimentos/métodos , Rutina/análise , Cor , Alimentos Fortificados/análise , Quercetina/química , Reologia , Rutina/química , Sementes/química , Amido/química , Temperatura Ambiente , Viscosidade
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