Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24.158
Filtrar
1.
J Contemp Dent Pract ; 20(7): 873-877, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31597812

RESUMO

AIM: The aim of this study is to report manufacturing a consolidated pulp test system that includes thermometry, flowmetry, and pulse oximetry. BACKGROUND: The ideal method for the evaluation of pulp vitality should be objective, noninvasive, easy to use, reliable, and painless. Currently, the most commonly used tests (such as electricity, heat, and cold tests) depend on patients' sensibility and are highly subjective. They only measure a neural response and do not indicate the actual biologic status of the pulp. It has, therefore, been suggested that vitality tests such as flowmetry, pulse oximetry, thermometry, and photoplethysmography be used. Some research has been done on these systems; however, their high costs and space need to maintain all of them that have been obstacles to their use. TECHNIQUE: This report describes designing and manufacturing a novel system for evaluating pulp vitality involving the use of three methods (flowmetry, pulse oximetry, and thermometry) combined in a single small system using only two probes. CONCLUSION: The consolidated pulp tests system may be accurate in determining the pulp vitality. However, after clinical use, some changes may be necessary for improvement of the system.


Assuntos
Teste da Polpa Dentária , Oximetria , Polpa Dentária , Temperatura Alta , Humanos , Reologia
2.
Braz Oral Res ; 33: e040, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508724

RESUMO

The study characterizes dental implant surfaces treated with phosphoric acid to assess the effects of acid treatment on blood cells and correlate them with cytokine levels. The implant surfaces examined were divided into untreated metal surface (US; n = 50), metal surface treated with phosphoric acid (ATS; n = 50) and cement surface (CS; n = 50) groups. The samples were characterized by scanning electron microscopy (SEM) and rheometry. The implants were incubated with human blood mononuclear cells for 24 h, with surface rinsing in the ATS treatment. Cell viability was determined by colorimetric methods and cytokines in the culture supernatant were quantified using flow cytometry. In the ATS group, the surface porosity and contact surface were increased and plaques were observed on the surface. The blood flow and viscosity curves were similar among the treatments, and the high cell viability rates indicate the biocompatibility of the materials used. An increase in the levels of IL-2, IL-4, IL-6, IL-10 and TNF-α was observed in the ATS and CS groups. There were positive correlations between IL-10 and IL-2 levels and between IL-10 and IL-4 levels in the culture supernatant of the ATS group. The results suggest that implant surface treatment with phosphoric acid activates the production of inflammatory cytokines. The increased cytokine levels can modulate the immune response, thereby improving biofunctional processes and promoting the success of dental implants.


Assuntos
Citocinas/análise , Implantes Dentários , Materiais Dentários/farmacologia , Leucócitos Mononucleares/efeitos dos fármacos , Ácidos Fosfóricos/farmacologia , Anti-Inflamatórios , Sobrevivência Celular , Citocinas/metabolismo , Cimentos Dentários , Humanos , Interleucina-10/análise , Interleucina-10/metabolismo , Microscopia Eletrônica de Varredura , Reologia , Propriedades de Superfície
3.
J Agric Food Chem ; 67(40): 11025-11034, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31502841

RESUMO

Recently, we have observed a relationship between poor breadmaking quality and protease activities related to fungal infection. This study aims to identify potential gluten-degrading proteases secreted by fungi and to analyze effects of these proteases on rheological properties of dough and gluten. Fusarium graminearum-infected grain was used as a model system. Zymography showed that serine-type proteases secreted by F. graminearum degrade gluten proteins. Zymography followed by liquid chromatography-mass spectrometry (MS)/MS analysis predicted one serine carboxypeptidase and seven serine endo-peptidases to be candidate fungal proteases involved in gluten degradation. Effects of fungal proteases on the time-dependent rheological properties of dough and gluten were analyzed by small amplitude oscillatory shear rheology and large deformation extensional rheology. Our results indicate that fungal proteases degrade gluten proteins not only in the grain itself, but also during dough preparation and resting. Our study gives new insights into fungal proteases and their potential role in weakening of gluten.


Assuntos
Carboxipeptidases/metabolismo , Endopeptidases/metabolismo , Proteínas Fúngicas/metabolismo , Fusarium/enzimologia , Glutens/metabolismo , Doenças das Plantas/microbiologia , Triticum/microbiologia , Carboxipeptidases/química , Endopeptidases/química , Farinha/análise , Farinha/microbiologia , Proteínas Fúngicas/química , Fusarium/fisiologia , Glutens/análise , Espectrometria de Massas , Reologia , Triticum/química , Triticum/metabolismo
4.
J Agric Food Chem ; 67(35): 9907-9915, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31436102

RESUMO

The impact of covalent or non-covalent bound gallic acid (GA) on the formation, physicochemical properties, and digestion of ovotransferrin (OTF) nanofibrils was comprehensively studied. Thioflavin T fluorescence results revealed that bound GA could inhibit OTF nanofibrillation and that the fibril-inhibitory activity of bound GA was dose dependent. Covalent bound GA exerted stronger inhibition on OTF nanofibrillation than an equal amount of non-covalent bound GA. Atomic force microscopy revealed that covalent bound GA shortened OTF nanofibrils significantly, while non-covalent bound GA did not change the contour length of OTF fibrils remarkably. Bound GA altered diameter of OTF nanofibrils. Both covalent and non-covalent bound GA could alter the zeta potential, surface hydrophobicity, and rheological properties of OTF nanofibrils. Bound GA endowed OTF nanofibrils with a strong antioxidant activity. In vitro gastrointestinal digestion results showed that covalent bound GA elevated the fibril digestion rate better than non-covalent bound GA. Polyphenol binding provided a new approach to modulating the physicochemical properties of protein nanofibrils.


Assuntos
Conalbumina/química , Ácido Gálico/química , Nanofibras/química , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Galinhas , Conalbumina/metabolismo , Digestão , Ácido Gálico/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Modelos Biológicos , Reologia
5.
J Cosmet Sci ; 70(3): 127-136, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31398101

RESUMO

The impact that rhamnolipid (RL) and sophorolipid (SL) biosurfactants has on solution surface activity when used in conjunction with the commercially important zwitterionic surfactant cocamidopropyl betaine (CAPB) is highlighted for the first time through surface tension and surface rheology measurements on binary and ternary mixtures of these surfactants. It was observed that in both the binary (CAPB/RL) and the ternary (CAPB/RL/SL) mixtures, RL tends to dominate at the air-water interface and primarily control both surface tension and surface elasticity behavior. Significant reduction of surface tension and enhancement of surface elasticity is observed as a result of the competitive adsorbtion/dominance of the RL at the air-water interface and this leads to performance enhancements in terms of foam stability.


Assuntos
Micelas , Tensoativos/química , Reologia , Tensão Superficial , Água
6.
Food Chem ; 298: 125081, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260952

RESUMO

The impact of kansui on the dough rheology and quality characteristics of chickpea-wheat composite flour-based noodles was investigated. For noodle dough, both the relative crystallinity and degree of order obtained from X-ray diffraction and Fourier transform infrared spectroscopy increased with the low level of kansui addition (0.5-1.5%), followed by a decreased trend at higher levels of alkali concentration (2.0-3.0%). Such variation was in accordance with the trend observed for G' and G″. Based on the confocal laser scanning microscopic observation for cooked noodle samples, the low concentration of kansui addition (0.5-1.5%) protected the well-embedded starch granules being disassociate from the gluten network, whereas with the increased alkali addition (2.0-3.0%), the protein network was impaired with a greater amount of ruptured starch granules being disassociated from the gluten network. The observation corresponded well with the electrophoretic profile, and the results of cooking properties, -SH content, and textural properties of cooked noodles.


Assuntos
Cicer/química , Farinha , Triticum/química , Carbonatos/química , Culinária , Qualidade dos Alimentos , Glutens/química , Microscopia Confocal , Potássio/química , Reologia , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/química , Difração de Raios X
7.
Food Chem ; 299: 125115, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31288161

RESUMO

The nutritional and antinutritional components of minor millets were correlated with mixolab dough mixing behavior and in vitro protein and starch digestibility. Total arabinoxylan (r = -0.53, p < 0.05) and dietary fiber (r = -0.66, p < 0.05) content significantly (p < 0.05) increased protein weakening. Peak viscosity negatively correlated with phenolic (r = -0.55, p < 0.05) content. The dietary fiber and phenolics suppressed retrogradation. Protein digestibility negatively correlated with tannin (r = -0.70, p < 0.05), phytic acid (r = -0.69, p < 0.05), phenolics (r = -0.79, p < 0.05), flavonoids (r = -0.72, p < 0.05) and total dietary fiber content (r = -0.84, p < 0.05). A positive correlation of resistant starch (RS) with total dietary fiber (r = 0.85, p < 0.05), phenolics (r = 0.89, p < 0.05), flavonoids (r = 0.83, p < 0.05), phytic acid (r = 0.43, p < 0.05) and tannin content (r = 0.79, p < 0.05) was observed. Millets predicted lower glycemic index than wheat and it was found to be negatively associated with the RS (r = -0.96, p < 0.05) and total dietary fiber content (r = -0.89, p < 0.05) and positively correlated (r = 0.98, p < 0.05) with rapidly digestible starch. The millets may be diversified for personalized nutrition and development of functional food.


Assuntos
Pão , Milhetes , Proteínas de Vegetais Comestíveis/farmacocinética , Amido/farmacocinética , Fibras na Dieta/análise , Digestão , Índice Glicêmico , Milhetes/química , Panicum/química , Fenóis/análise , Fenóis/química , Reologia , Setaria (Planta)/química , Amido/química , Triticum/química , Viscosidade , Xilanos/análise
8.
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
9.
Food Chem ; 300: 125171, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31330369

RESUMO

This study aimed to examine the modification effect of whey protein concentrate (WPC), WPC-gum arabic (WPC-GA) or WPC-high methoxyl pectin (WPC-PEC) complex to tailor-modify W/O/W emulsion for secondary microencapsulation of hydrophilic arbutin and hydrophobic coumaric acid. The stability and rheological properties of coated emulsions, encapsulation yield, release and degradation kinetics of arbutin and coumaric acid were investigated. Results revealed that WPC-PEC complex (at the ratio of 1:3) coating W/O/W emulsion exhibited the highest viscosity and stability, with the highest encapsulation yield of 91.08% for arbutin and 80.92% for coumaric acid, respectively. Tighter coating structure of the WPC-PEC complex (1:3) forming a stronger gel network structure was confirmed, accounting for the larger mean particle size of 569.67 nm. Moreover, the WPC-PEC (1:3) coating W/O/W emulsion also showed controlled release of arbutin and coumaric acid in simulated conditions. The k value of degradation kinetics for arbutin (7.99 × 10-4 at pH = 1.2, 4.19 × 10-4 at 90 °C and 7.52 × 10-4 at UV-C treatment) and coumaric acid (5.18 × 10-4 at pH = 1.2, 3.24 × 10-4 at 90 °C and 6.90 × 10-4 at UV-C treatment) indicated low degradation rate. The present study revealed that the WPC-PEC (1:3) coating W/O/W emulsion could provide a better synergistic effect on higher encapsulation yield and stability of arbutin and coumaric acid.


Assuntos
Arbutina/química , Cápsulas/química , Ácidos Cumáricos/química , Emulsões/química , Polissacarídeos/química , Arbutina/farmacocinética , Composição de Medicamentos , Goma Arábica/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Pectinas/química , Reologia , Temperatura Ambiente , Raios Ultravioleta , Viscosidade , Proteínas do Soro do Leite/química
10.
Food Chem ; 300: 125201, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357016

RESUMO

Quinoa starch granules were esterified with dodecenyl succinic anhydride (DDSA) to various degrees of substitution (DS) (0.0023-0.0095). Physicochemical properties and emulsification capacity of the modified starch were studied. Increasing DS increased the particle size, water solubility, and swelling power, while decreasing the gelatinization enthalpy change and relative crystallinity of the starch. The DDSA groups were suggested to be mostly located in the amorphous region of starch granules. With increasing DS, the viscosity and storage modulus (G') obtained from rheological analysis increased first and then decreased. The DDSA modified quinoa starch efficiently stabilized O/W Pickering emulsions and has some technical advantages compared to octenyl succinic anhydride (OSA)-modified quinoa starch. Increasing DS led to decreased droplet size of the emulsions and a higher capacity in stabilizing emulsions during storage for a period of 10 days. This study suggested the potential application of DDSA modified quinoa starch as an emulsifier in stabilizing Pickering emulsions.


Assuntos
Chenopodium quinoa/química , Amido/química , Anidridos Succínicos/química , Emulsões , Tamanho da Partícula , Reologia , Viscosidade
11.
Soft Matter ; 15(30): 6190-6199, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31328216

RESUMO

The evaporation of colloidal solutions is frequently observed in nature and in everyday life. The investigation of the mechanisms taking place during the desiccation of biological fluids is currently a scientific challenge with potential biomedical and industrial applications. In the last few decades, seminal works have been performed mostly on dried droplets of saliva, urine and plasma. However, the full understanding of the drying process in biocolloids is far from being achieved and, notably, the impact of solute properties on the morphological characteristics of the evaporating droplets, such as colloid segregation, skin formation and crack pattern development, is still to be elucidated. For this purpose, the use of model colloidal solutions, whose rheological behavior is more easily deducible, could represent a significant boost. In this work, we compare the drying of droplets of whey proteins and casein micelles, the two main milk protein classes, to that of dispersions of silica particles and polymer-coated silica particles, respectively. The mechanical behavior of such biological colloids and model silica dispersions was investigated through the analysis of crack formation, and the measurements of their mechanical properties using indentation testing. The study reveals numerous analogies between dairy and the corresponding model systems, thus confirming the latter as a plausible powerful tool to highlight the signature of the matter at the molecular scale during the drying process.


Assuntos
Caseínas/química , Laticínios/análise , Dessecação , Micelas , Proteínas do Soro do Leite/química , Fenômenos Mecânicos , Modelos Químicos , Reologia
12.
J Agric Food Chem ; 67(32): 8725-8734, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31295997

RESUMO

Texture perception is conceptualized as an emergent cognitive response to food characteristics that comprise several physical and chemical properties. Contemporary oral processing research focuses on revealing the relationship between the sensory perceptions and food properties, with the goal of enabling rational product design. One major challenge is associated with revealing the complex molecular and biocolloidal interactions underpinning even simple texture percepts. Here, we introduce in vitro oral processing, which considers oral processing in terms of discrete units of operation (first bite, comminution, granulation, bolus formation, and tribology). Within this framework, we systematically investigate the material properties that govern each specific oral processing unit operation without being impacted by the biological complexity of the oral environment. We describe how this framework was used to rationally design a low-fat potato chip with improved sensory properties by investigating the impact from adding back, to a low-fat potato chip, a small amount of oil mixed with the surface-active agent polyglycerol polyricinoleate (PGPR). The relevance of instrumental measures is validated by sensory assessment, whereby panelists ranked the perceived oiliness of three different types of potato chips. The sensory results indicate that perceived oiliness was higher when a low-fat potato chip was supplemented with an additional 0.5% (w/w) topical coating (the coating comprised 15%, w/w, PGPR in oil) compared to the unaltered low-fat potato chip. The perceived difference in oiliness is hypothesized to correspond to the dynamic friction measured in vitro with a saliva-coated substrate in the presence and absence of PGPR. The study illustrates how dividing oral processing into distinct units provides a rational approach to food product design focused on controlling key sensory attributes.


Assuntos
Gorduras/análise , Boca/metabolismo , Solanum tuberosum/metabolismo , Gorduras/metabolismo , Manipulação de Alimentos , Humanos , Modelos Biológicos , Reologia , Saliva/metabolismo , Lanches , Solanum tuberosum/química
13.
Food Chem ; 300: 125221, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31351256

RESUMO

In this study, water-soluble curdlan products (Cur and Cur-D) were prepared by an alkali-neutralization treatment process, after which ferulic acid (FA)-grafted Cur conjugates (Cur-g-FA and Cur-D-g-FA) were fabricated in the presence and absence of salt by adopting an approach involving free-radicals generated by the ascorbic acid/hydrogen peroxide redox pair under an inert atmosphere. Results showed that FA was successfully grafted onto the C-6 and C-4 positions of the Cur chains through covalent linkages and that the presence of salt exerted minor influences on the grafting ratios and structural characterizations of the products. Cur-g-FA and Cur-D-g-FA showed decreased crystallinity, thermal stability, and rheological properties, as well as a distinct surface morphology, when compared with those of native Cur. However, Cur-g-FA and Cur-D-g-FA also exhibited remarkably enhanced free-radical scavenging ability and antioxidant capacity in vitro. These results indicate that FA-grafted Cur conjugates have great potential application in the field of functional foods.


Assuntos
Antioxidantes/química , Ácidos Cumáricos/química , beta-Glucanas/química , Antioxidantes/farmacologia , Ácido Ascórbico/química , Radicais Livres/química , Peróxido de Hidrogênio/química , Oxirredução , Reologia , Solubilidade , Propriedades de Superfície , Água/química
14.
Nature ; 571(7766): 560-564, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31292551

RESUMO

The biophysical relationships between sensors and actuators1-5 have been fundamental to the development of complex life forms. Swimming organisms generate abundant flows that persist in aquatic environments6-13, and responding promptly to external stimuli is key to survival14-19. Here we present the discovery of 'hydrodynamic trigger waves' in cellular communities of the protist Spirostomum ambiguum that propagate-in a manner similar to a chain reaction20-22-hundreds of times faster than their swimming speed. By coiling its cytoskeleton, Spirostomum can contract its long body by 60% within milliseconds23, experiencing accelerations that can reach forces of 14g. We show that a single cellular contraction (the transmitter) generates long-ranged vortex flows at intermediate Reynolds numbers that can, in turn, trigger neighbouring cells (the receivers). To measure the sensitivity to hydrodynamic signals in these receiver cells, we present a high-throughput suction-flow device for probing mechanosensitive ion channels24 by back-calculating the microscopic forces on the cell membrane. We analyse and quantitatively model the ultra-fast hydrodynamic trigger waves in a universal framework of antenna and percolation theory25,26, and reveal a phase transition that requires a critical colony density to sustain collective communication. Our results suggest that this signalling could help to organize cohabiting communities over large distances and influence long-term behaviour through gene expression (comparable to quorum sensing16). In more immediate terms, because contractions release toxins27, synchronized discharges could facilitate the repulsion of large predators or immobilize large prey. We postulate that numerous aquatic organisms other than protists could coordinate their behaviour using variations of hydrodynamic trigger waves.


Assuntos
Comunicação Celular , Cilióforos/citologia , Cilióforos/fisiologia , Hidrodinâmica , Natação/fisiologia , Movimentos da Água , Animais , Organismos Aquáticos/citologia , Organismos Aquáticos/genética , Organismos Aquáticos/fisiologia , Biofísica , Cilióforos/genética , Citoesqueleto/fisiologia , Comportamento Predatório , Reologia , Fatores de Tempo
15.
Georgian Med News ; (290): 59-63, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31322516

RESUMO

The goals of this project were to determine how hemodynamics and hemorheological change in patients diagnosed with different forms of atrial fibrillation; also, how relievers of changes in fibrinogen monitoring in patients with permanent, persistent, paroxysmal forms of arrhythmias. There was examined 30 patients (the average age of patients 65). Patients and control groups have been tested the following studies: index of erythrocytes aggregability, deformability, plasma viscosity to evaluate the blood rheological parameter, also -Fibrinogen to determine of coagulation condition. The Index of the Erythrocytes aggregation was done with the system of textural analyzes. These new innovative methods "Georgian Technique" is created by Georgian scientists and they are famous in the world as direct, numeral and exact. The index of the deformation of the erythrocytes was done with filtration method. Plasma viscosity was measured in the capillary viscosimeter in 370 C. According to the obtained data patients with atrial fibrillation have the same conditions of rheological and coagulation systems, despite of the forms of the atrial fibrillation. And it is different compared to the control group. In the statistical processing of the total row of fibrinogen, the patients were divided into 3 categories. As it turned out fibrinogen and Index of erythrocytes aggregation are in a linear relationship. The quantity of fibrinogen and of erythrocytes aggregation increase simultaneously and the greater the sequential number of the category is, the changes are more pronounced. However, the change/variability of each biological parameter, as shown from our data, is not uniform and linear. The obtained results clearly illustrate the existence of two parallel mechanisms in the body. These are on the one hand the systems of coagulation, anti-coagulation and fibtinollysis. These processes are in a state of the weighted condition, and they are characterized by dynamic equilibrium. On the other hand, the rheology system, which involves the combination of blood flow, blood velocity, vascular stiffness / elasticity, is characterized by one direction going on, with the adequacy and non-existing antipodal mechanisms. The hemorheological system does not have a physiologically balanced opposing anti-rheological system. All of this generate that the hemorheological status is very important in the development and formation of some disease. The arrangement of a rheologycal system is taking preventive character. On the one hand, the rheologycal system is a consolidation of diagnosis and evaluation of the mechanisms. Also, it is the treatment target. Normalization of them is very important in the therapeutic standpoint of the individual.


Assuntos
Fibrilação Atrial/sangue , Agregação Eritrocítica/fisiologia , Fibrinogênio/fisiologia , Reologia , Idoso , Idoso de 80 Anos ou mais , Fibrilação Atrial/fisiopatologia , Viscosidade Sanguínea/fisiologia , Estudos de Casos e Controles , Deformação Eritrocítica , Eritrócitos , Feminino , Hematócrito , Humanos , Masculino
16.
Georgian Med News ; (290): 140-144, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31322532

RESUMO

Given the large enough area of the spread of acne disease, research is needed on the development of the new versions of preparations. Cosmetics and cosmeceuticals of daily use are easy to consume as preventive remedies during mild form of the disease at an early stage. These remedies include powders, which women tend to use every day, and men, if necessary, but quite often. Powder should fit the skin, not be crumbled during the air disturbance and be kept on the face for a relatively long time, have hygroscopicity, that is, they should absorb the sweat and fat. When developing formula of similar powder, we used the available literature data on remedies using for the treatment of acne. There have been studied some technological and rheological properties of powders, such the bulk specific gravity, bulk density and natural angle of slope. Given that all parameters depend on the dispersion and a specific surface of powder, the shape of the particles and their size distributions, we used the particles of all ingredients with a size of 3 to 20 µm. The obtained powder samples are easily applied to the skin, keeping on it for at least 4-5 hours. When applied to the oily skin, there are not observed swelling of starch and coating of pores, as well as the formation of a colloidal structure of bentonite clay. For the first time, a new formula is proposed for acne treating powders containing both plant and mineral components, determining both the structural features of powder and those features that are involved in certain processes that help to increase the pharmacological effect.


Assuntos
Acne Vulgar/terapia , Pós/uso terapêutico , Extrato de Sementes de Uva/química , Extrato de Sementes de Uva/uso terapêutico , Humanos , Preparações de Plantas , Pós/química , Reologia , Pele , Óxido de Zinco/química , Óxido de Zinco/uso terapêutico , Sulfato de Zinco/química , Sulfato de Zinco/uso terapêutico
17.
Phys Rev Lett ; 122(21): 218102, 2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31283330

RESUMO

Dynamically cross-linked semiflexible biopolymers such as the actin cytoskeleton govern the mechanical behavior of living cells. Semiflexible biopolymers nonlinearly stiffen in response to mechanical loads, whereas the cross-linker dynamics allow for stress relaxation over time. Here we show, through rheology and theoretical modeling, that the combined nonlinearity in time and stress leads to an unexpectedly slow stress relaxation, similar to the dynamics of disordered systems close to the glass transition. Our work suggests that transient cross-linking combined with internal stress can explain prior reports of soft glassy rheology of cells, in which the shear modulus increases weakly with frequency.


Assuntos
Citoesqueleto/química , Citoesqueleto de Actina/química , Actinas/química , Humanos , Modelos Químicos , Dinâmica não Linear , Reologia , Estresse Mecânico
18.
Carbohydr Polym ; 219: 162-171, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31151513

RESUMO

Rheological behaviors of microbial polysaccharides with different substituents in aqueous solutions have been systematically investigated. Both the saccharide side chains and acetyl substituents improve the gelation of welan gum (WG), diutan gum (DG) and gellan gum (GG) in pure water at 25 °C. For the polysaccharides with saccharide side chains (WG and DG), the relationship between the apparent viscosity and concentration conforms to the linear equation, while that of the polysaccharide with acetyl (GG) is exponential. More importantly, the roles of substituents on the stability of the molecular conformation of polysaccharides are significantly depended on the surrounding environment. Disaccharide side chains promote the stability of helical conformation and gel aggregates of GG at high temperature (85 °C) or in the presence of inorganic salts with the ionic strength of 2.0 mol L-1. The stability of gel structure containing acetyl (GG) shows higher temperature/salt sensitivity. Additionally, deacylated gellan gum (GG(d)) solutions transform into hydrogels in the presence of dodecyltrimethylammonium bromide (DTAB). This study will help to obtain a better understanding on the rheological properties of polysaccharides with respect to the conformation and applications.


Assuntos
Bactérias/metabolismo , Hidrogéis/química , Polissacarídeos Bacterianos/química , Reologia , Tensoativos/química , Ácido Acético/química , Concentração Osmolar , Sais/química , Soluções/química , Temperatura Ambiente , Viscosidade
19.
Food Chem ; 297: 124978, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253262

RESUMO

Rice glutelin (RG) and phosphorylated rice glutelin (PPRG) were treated with heating for different time (15, 30, and 45 min), the effects of phosphorylation modification on the structure, interactions and rheological properties of rice glutelin during heat treatment were investigated. The results showed that the turbidity of PPRG samples were higher than those of RG samples after heating. Particle size distribution showed that the protein aggregates with particle size of 1000-1500 nm were formed after heating for 45 min. Changes in protein structure indicated that the protein unfolded after heating for a short time, and aggregated when heating time extended to 45 min. In addition, the microstructure of PPRG sample became tight when heated for 45 min. Rheological analysis showed that phosphorylation modification and heat treatment improved RG viscoelasticity. These results suggest that phosphorylation modification improves thermal aggregation of RG, which will facilitate the application of RG in food industry.


Assuntos
Glutens/análise , Estrutura Molecular , Oryza/química , Agregados Proteicos , Reologia , Indústria Alimentícia , Calefação , Temperatura Alta , Tamanho da Partícula , Fosforilação , Viscosidade
20.
Soft Matter ; 15(27): 5455-5463, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31231747

RESUMO

Development of fast force volume (FFV), PeakForce Tapping (PFT), and related AFM techniques allow fast acquisition and mapping of a sample's mechanical properties. The methods are well-suited for studying soft biological samples like living cells in a liquid environment. However, the question remains how the measured mechanical properties are related to those acquired with the classical force volume (FV) technique conducted at low indentation rates. The difference is coming mostly from the pronounced viscoelastic behavior of cells, making apparent elastic parameters depending on the probing rate. Here, the viscoelastic analysis was applied directly to the force curves acquired with force volume or PeakForce Tapping by their post-processing based on the Ting's model. Maps from classical force volume, FFV and PFT obtained using special PFT cantilevers and cantilevers modified with microspheres were compared here. With the correct viscoelastic model, which was found to be the power-law rheology model, all the techniques have provided self-consistent results. The techniques were further modified for the mapping of the viscoelastic model-independent complex Young's modulus.


Assuntos
Fibroblastos/citologia , Animais , Linhagem Celular , Simulação por Computador , Módulo de Elasticidade , Camundongos , Microscopia de Força Atômica , Ratos , Reologia , Propriedades de Superfície , Viscosidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA