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关键词： contact guidance   freeze-cast   release   scaf-folds   tissue engineering  

摘要： In this study, retinoic acid loaded-PLGA-gelatin matrixes were prepared with both freeze-casting and freeze-drying techniques. Herein, the effect of unidirectional microstructure with tunable pores on release profile, cellular adhesion, migration, and differentiation was compared. Morphological observation determined that highly interconnected porous structure can be formed, but lamellar pore channels were observed in freeze-casting prepared constructs. The absorption ratio was increased, and the biodegradation rate was decreased as a function of the orientation of microstructure. The in-vitro release study illustrated non-Fickian release mechanism in both methods, so that erosion has predominated over diffusion. Accordingly, PLGA-gelatin scaffolds prepared with freeze-drying technique showed no adequate erosion due to the rigid structure, while freeze-casting one presented more favorable erosion. Microscopic observations of adhered P19 embryonic cells on the scaffolds showed that the freeze-casting matrixes with unidirectional pores provide a more compatible microenvironment for cell attachments and spreading. Besides, it facilitated cell migration and penetration inside the structure and may act as guidance for neuron growth. Improvement in the expression of neural genes in unidirectionally oriented pores proved the decisive role of contact guidance for nerve healing. It seems that the freeze-cast PLGA- gelatin-retinoic acid scaffolds have initial features for nerve tissue regeneration studies.

关键词： Optical materials   Crystal growth   X-ray diffraction   Nonlinear absorption   Z-scan   Optical limiting  

摘要： Herein we report the tunable optical limiting property of a metal-organic cesium tetroxalate dihydrate (CTD) complex. Temperature and pH were optimized to be 40 degrees C and 3.5 respectively to grow CTD single crystal using the solvent evaporation method. The compound formation was confirmed by its response to single crystal and powder x-ray diffraction analysis. Thermal, mechanical, dielectric, linear optical, photoconductivity and photoluminescence properties of title crystal are reported. Nonlinear coupling between delocalized pi-electrons of metal-ligand interaction and the oscillating electric field of a laser beam enhanced the nonlinear optical parameters. The third order nonlinear refractive index (n(2)), absorption coefficient (beta) and susceptibility (chi((3))) of CTD complex under continuous-wave laser excitation are found to be (3.26 +/- 0.033) x 10(-8) cm(2) W-1, (10.33 +/- 0.41) x 10(-4) cmW(-1) and (8.98 +/- 0.35) x 10(-5) esu respectively. Variation in two-photon absorption (2PA) coefficient measured under nanosecond pulsed laser excitation of different intensities confirmed the presence of sequential 2PA in CTD complex. The optical limiting threshold was investigated under different intensities were found to vary from (1.09 +/- 0.05) x 10(12) Wm(-2) to (2.49 +/- 0.05) x 10(12) Wm(-2) showing the intensity tunable optical limiting property of CTD material.

关键词： Egg yolk   Phosphorylation   Succinylation   Emulsification   Gelation  

摘要： This study aimed to verify influence of sodium tripolyphosphate and succinic anhydride on functional characteristics of egg yolk (EY). Addition of the two salts led to modification of yolk protein, and modification degree improved with increasing reaction time. Two modification methods caused a two-to three-fold enhancement in emulsion stability of EY. The hardness of yolk gels was effectively increased by 29.73% or 56.61%. The improved emulsion stability and gelling properties of the modified EY resulted from changed structures of EY protein. Physicochemical properties, such as increased solubility as well as decreased surface hydrophobicity, particle size of yolk granules, and zeta potential, contributed to the enhanced functional properties. The result of scanning electron microscopy revealed that modification was beneficial in forming fine and compact EY gel network. The gel strength and water-holding capability of the yolk gels were thus considerably increased.

关键词： Folic acid   Gastrointestinal-resistant composite   Controlled release   Alginate   Pectin  

摘要： Potential effects of folates on the treatment of several human diseases like cognitive function, neural tube defects, coronary heart disease and certain kinds of cancers have been discovered. However, the stability of folic acid against adverse conditions is a great concern. The present study investigates various alginate (A)-pectin (P) gastrointestinal-resistant hydrogel to immobilize folic acid. This involves evaluating different compositions of alginate-pectin to achieve higher encapsulation efficiency and stability during simulated gastric (SG) and simulated intestinal (SI) conditions. Coated alginate hydrogels with pectin resulted significant (p < 0.05) better protection of folic acid compared to non-coated alginate hydrogel when exposed to SG condition and when exposed to SI condition, sustained release behavior obtained with the ratio of A70-P30. The structural and physicochemical properties of blended A-P hydrogel were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffractometer, indicating the presence of folic acid into the matrix and signified no covalent reaction between components. Therefore, this adequate composition of alginate-pectin showed to be a potential carrier for folic acid stability.

关键词： polymerization   2-[(2Z   E)-2-chloro-1-methylbut-2-en-1-yl]aniline   dopants of different nature   solubility   conductive polymer   sensors  

摘要： Highly soluble polyaniline was synthesized from a newly designed aniline derivative, namely 2-[2-chloro-1-methylbut-2-en-1-yl]aniline. The corresponding polyanilines, PClPA-HA, PClPA-SA, PClPA-NA and PClPA-PA, were characterized by means of H-1 NMR, C-13 NMR, high resolution mass spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and SEM images. The elemental analysis and electrical conductivity of the polymers are also presented. It is shown that the molecular weight of the polymers obtained depends on the method of synthesis. Spectroscopic studies confirmed the emeraldine form of the polyaniline derivatives. In the work, the dependence of the current passing through resistive structures based on thin poly[2-(2-chloro-1-methylbut-2-en-1-yl)aniline] films on the relative humidity of air was studied. The results of the studies showed the prospects of using thin polymer films in the design of chemical sensors. (c) 2020 Society of Chemical Industry

关键词： Microencapsulation   Red mombin juice   Rotatable central composite design   Spray drying  

摘要： Optimal spray drying conditions were selected to microencapsulate red mombin juice and maximize carotenoid retention. Microencapsulation was optimized following a rotatable central composite design where inlet temperature, feed flow rate, and maltodextrin concentration were chosen as independent variables. The powder prepared under optimized conditions, whose reconstituted nectar was the most appreciated by sensory analysis, exhibited a high total phenolic content and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging capacity, and its physicochemical properties proved to be suitable for applications in the food industry.

关键词： Water absorption  

摘要： This study aimed to evaluate the changes throughout storage of pasta formulations enriched with basil, beet, cheese, chocolate, coffee, dried tomato, ginger, pepper, rosemary, socol, spinach, and wine in metallic and transparent packages. Pasta color, moisture content, water activity (a(w)), pH, total titratable acidity, cooking time, water absorption, and cooking loss were evaluated for 120 days. The packages used were efficient throughout storage in preserving moisture,a(w), pH, total titratable acidity, cooking time, and water absorption for all formulations. Cooking loss and kinetics of the total color difference (Delta E) of some pasta were significantly (p < .05) affected. Beet pasta was the only one that showed a significant difference in cooking loss (p < .05) and Delta E was not influenced by packaging and storage time. Spinach pasta presented the largest Delta Ebetween the two packaging types after 120 days. The metallic packaging was better at preservation of the pasta color throughout storage. Practical applications Adding ingredients in pasta formulations is a good alternative for the manufacture of products with attractive consumer features. Storage time and packaging are factors that can influence the quality of pasta, generating characteristics that may affect the product. Therefore, the study of these factors for different types of pasta provides relevant information for the food industries, since it is possible to identify the storage conditions that promote the lower change in quality. The results indicated that storage time and packaging are factors that influenced mainly the preservation of color characteristics of pasta containing added nontraditional ingredients. Metallic packaging can be considered an efficient alternative to reduce color change throughout the storage.

关键词： trachyandesibasalt   mineral composition   melting   magnetic properties  

摘要： We studied by physicochemical modeling (PCM) how the temperature and redox properties of the crystallization atmosphere affect the equilibrium compositions of product phases using trachyandesibasalt as an example. The chemical composition of rock-forming minerals and their influence on the properties of rocks are presented. The heating, melting, and crystallization features of trachyandesibasalt are considered taking into account external conditions and the mutual influence of the minerals present in the rock. Temperature-dependent magnetization is determined for various fractions of the studied rock. The fundamental possibility is shown, and recommendations are given, for choosing methods to modify the chemical and mineral composition of trachyandesibasalt.

关键词： Differential scanning calorimetry   Thermogravimetric analysis   Pyrolysis   Lignocellulosic biomass  

摘要： This research paper is about the kinetics of drying and pyrolysis processes of lulo (Solanum quitoense Lam.) peel powder, which was studied using thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and mass spectrometry (MS). TG data was fitted using theoretical approximation according to the Newton model to obtain the kinetic parameters of drying, and the isoconversional methodology using Friedman's method for the pyrolysis process. The results of each thermogram showed a relation between each other. In all of them, three characteristic stages were identified related to drying, pyrolysis, and carbonaceous matter. At the same time, there was a decomposition of the lignocellulosic biomass and light volatiles in the pyrolysis process. In the thermograms, three characteristic stages were identified: the first stage is the dehydration which ended at 120 degrees C, the second is the pyrolysis which is between 120 and 450 degrees C, and from this temperature, the third stage, carbonization, begins. In the pyrolysis stage, five peaks corresponding to independent reactions were identified;activation energy (E-a) and the reaction mechanism (f(alpha)) of each peak were calculated by means of master curves. After comparing the theoretical and experimental master plots, it was observed that the reaction mechanism corresponds to the Avrami-Erofeev model. Thermal analyses indicate that lulo peel is a potential waste for the production of coal for power purposes. It could be contributing to improve the management of waste and at the same time it could be used as a power supply or for water treatments such as activated carbon.

关键词： biopolymers   1,3-beta-D-glucan   vibrational spectroscopy   X-ray photoelectron spectroscopy   AFM microscopy   biomaterials  

摘要： In order to determine the effect of different gelation temperatures (80 degrees C and 90 degrees C) on the structural arrangements in 1,3-beta-d-glucan (curdlan) matrices, spectroscopic and microscopic approaches were chosen. Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) and Raman spectroscopy are well-established techniques that enable the identification of functional groups in organic molecules based on their vibration modes. X-ray photoelectron spectroscopy (XPS) is a quantitative analytical method utilized in the surface study, which provided information about the elemental and chemical composition with high surface sensitivity. Contact angle goniometer was applied to evaluate surface wettability and surface free energy of the matrices. In turn, the surface topography characterization was obtained with the use of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Described techniques may facilitate the optimization, modification, and design of manufacturing processes (such as the temperature of gelation in the case of the studied 1,3-beta-d-glucan) of the organic polysaccharide matrices so as to obtain biomaterials with desired characteristics and wide range of biomedical applications, e.g., entrapment of drugs or production of biomaterials for tissue regeneration. This study shows that the 1,3-beta-d-glucan polymer sample gelled at 80 degrees C has a distinctly different structure than the matrix gelled at 90 degrees C.