教学课程资源库 更多>>

关键词： Palm oil   Anhydrous milk fat   Shortening   SSHE   Cooling  

摘要： Commercial shortenings and margarines are mainly produced via rapid cooling with scraped surface heat exchangers (SSHE) and therefore, controlling fat crystallization in the cooling process of these systems plays an important role. In this study, four batches of puff pastry shortening were produced from palm oil blends containing 25% and 50% anhydrous milk fat (AMF) using a bench-top SSHE. The outlet temperature of SSHE was investigated at 20 degrees C and 12 degrees C relating to the difference of crystallization temperature between palm oil and milk fat. Physico-chemical properties, crystal morphology and fat stability of these shortenings during storage at 5 degrees C were determined by various classical technologies including differential scanning calorimetry (DSC), polarized light microscopy (PLM), rheological and texture analyzer. Our results showed that fat blends crystallized at 12 degrees C had a stronger crystal network after production but the discrepancy of hardness diminished after the first storage week at 5 degrees C. Besides, the change of crystallization temperature did not affect significantly melting behavior as well as fat polymorphism of products. Upon storage, some big aggregates were detected in shortenings as a combined result of the recrystallization of palm fat crystals and the post-crystallization of milk fat triacylglycerols (TAGs).

关键词： Silanes   Nanocomposites   Bisphenol a-glycidyl methacrylate   Operative dentistry   Hydrolysis   Polymerization   Toothbrushing  

摘要： Objective. To determine the effect of organosilane content on the physicochemical properties of model composites formulated with nano-sized fillers. Methods. Model composites were formulated with dimethacrylate-based monomers, a photoinitiator/co-initiator system and silicon dioxide nano-sized fillers treated with different amounts of 3-methacryloxypropyltrimethoxysilane (MPTS): 1.0 (G1%), 2.0 (G2%), 5.0 (G5%), 7.5 (G7.5%) and 10 (G10%) wt.% relative to SiO2. Non-silanized fillers (G0%) were used in the control group. Degree of conversion (DC) was assessed by Fourier-transformed infrared spectroscopy (ATR-FTIR). Knoop hardness (KHN) and elastic modulus were determined before and after water storage for 4 months. Water sorption (Wsp) and solubility (Wsl) were calculated by successive mass determinations in analytical balance. Surface gloss and roughness were characterized before and after toothbrushing simulation. Results. With the exception of those fillers treated with 1% MPTS, DC was not dependent on the silane content. Within the silanized groups, G1% showed the lowest initial and final KHN, without statistical difference from G0%. The elastic modulus was not affected by the silane content, regardless of the storage condition, but those groups formulated with at least 5% silane presented improved values after storage. Silane content did not affect the WSl, but affected Wsp, in which those groups formulated with at least 2 wt.% of MPTS produced a more resistant material than G0%. The use of treated particles with at least 2 wt.% of silane was able to produce materials that did not change their gloss after the brushing process. Additionally, these materials presented lower surface roughness than G0% after the brushing process (p < 0.05). Significance. The concentration of MPTS affected the physicochemical properties of nano filled composites. Therefore, 2 wt.% of silane was the optimized quantity to produce materials resistant to degradation, both in bulk and surfa

关键词： Pea root rot   Metabarcoding   Microbiome   Health status   Soil properties  

摘要： Aims: Field pea (Pisum sativum L.) is an important rotation crop in agriculture on the Canadian prairies. Pea root rot is caused by a complex of soilborne pathogens, and can have a tremendous impact on reducing yields and removing fields from pea production. The objectives of this study were to: determine whether characteristics of the fungal and bacterial microbiome are associated with diseased or healthy sites within pea fields, and assess whether abiotic soil properties differed between these diseased or healthy sites. Methods: Soil was collected from healthy and diseased sites within 5 fields across Alberta. Bacterial and fungal operational taxonomy units were determined using barcoded Illumina MiSeq of the 16S rRNA and internal transcribed spacer 1 (ITS) genes, respectively. Soil enzyme activities and soil physicochemical properties were also measured. Results: Principal coordinate analysis showed that health status was an important determinant of bacterial communities in two out of five fields and fungal communities in all fields. Microbial communities also differed between locations. However, there was no clear relationship between specific fungal or bacterial families, enzyme activities or soil properties with mot rot status. Conclusions: Although root rot severity and fungal community composition varied between healthy and diseased sites within a field, there was no consistent correlation of disease severity with biotic or abiotic soil properties across locations.

关键词： Food colorants   Natural pigments   Intelligent materials   Pigment recovery   Nanoparticles  

摘要： This study aims to develop and characterize biohybrids (BH) based on anthocyanins (ACNs) from jambolan (Syzygium cumini) and laponite (R) (Lap). ACNs from jambolan fruit were extracted using an acidified water solution at pH 1. ACNs were recovered from extract using Lap as adsorbent between 5 degrees C and 40 degrees C. There was no significant effect (p > 0.05) of the temperature on the adsorption process of ACNs. Thus, the process was classified as physical adsorption in heterogeneous sites where ACNs were stabilized by means of van der Waals force, pi - pi force, and hydrogen bonding on the Lap surface. After adsorption, the BH powder appeared to have an amorphous structure and red color. However, the color changed at pH >= 7. In addition, the obtained BH showed antioxidant properties and high stability when exposed to visible light irradiation. This research reports new information about the valorization and application of ACNs from jambolan for food industrial applications.

关键词： Actinides   Lung epithelial barrier   Translocation   Chelating agent  

摘要： The epithelial cell plays a key role in the transfer of radionuclides from lungs to blood following pulmonary exposure. The present study was designed to evaluate the transfer across human lung epithelial cells of various actinides (plutonium, americium and uranium), the influence of the physicochemical properties of plutonium compounds and of the chelating agent diethylene triamine pentaacetic acid (DTPA). To address this question, Calu-3 cells grown in a bicameral culture system were used. The integrity of the epithelial barrier was evaluated by measuring transepithelial electrical resistance (TEER) and the passage of a fluorescent marker, lucifer yellow. Activity measurement in basal compartment following periodic collection of culture medium was made from 2 h to seven days. To facilitate data handling and analysis, the statistical tool STATBIODIS was used. The results indicate differences in transfer for the different elements, and according to Pu physicochemical properties. Though to various extents, the chelating agent DTPA always increased the transfer of Pu and Am across the epithelial cells, without altering the integrity of the epithelial barrier. This in vitro cell culture model, by mimicking translocation of actinides from lungs to blood, can represent a valuable tool to further understand the underlying mechanisms and properties controlling this process.

关键词： Polyethylene glycols  

摘要： Organic-inorganic composites can be conveniently obtained by sol-gel recipes. They can find interesting applications in several fields, including drug delivery, scaffolding, bio-sensing, energetics, etc. Herein, we reconsider and reinvestigate our previous work in the field, by considering the sol-gel synthesis and physicochemical characterization of class-I organic-inorganic hybrids, and by trying to highlight some unifying elements that can be of help for the development of more efficient and precise synthesis methods. Systems based on poly(ethylene glycol) with SiO2 and ZrO2 as the ceramic phase will be discussed. Emphasis will be put on the role played by solid-state NMR spectroscopy in unveiling the interactions at the base of hybrid formation. © 2021 Wiley-VCH GmbH

关键词： Edible films   Tapioca starch   Zein   Physicochemical properties   Natural antimicrobials  

摘要： This work aimed to investigate the improvement of the performance of edible films based on tapioca starch containing natamycin and nisin, by the addition of zein. For that purpose, the effects on the physicochemical and antimicrobial properties of the developed films were evaluated. Results indicated that the addition of zein changed physicochemical properties, without altering the antimicrobial bioavailability of the films. The addition of zein improved the mechanical properties of the films, increasing the firmness at break and reducing the strain at break and also turned the films more yellow. Even more, in the presence of antimicrobials, the zein reduced water vapor permeability and water solubility and increased hydrophobicity.

关键词： Topaz-bearing rocks   Topaz   Geothermometry   Substitution of F- by OH-  

摘要： In highly evolved F-rich felsic igneous rocks, topaz Al2SiO4(F,OH)(2) forms in different genetic stages: orthomagmatic, pegmatitic, transitional magmatic-hydrothermal, and hydrothermal. The present study, considers some of the problems involved in deciphering the origin of OH-F variations in topaz. We conclude that topaz compositions in magmatic and post-magmatic hydrothermal stages range from pure fluor-topaz to about Al2SiO4F1.3(OH)(0.7). Magmatic topaz in rhyolites and topazites is extremely enriched in F, and topaz of hydrothermal origin may be more enriched in hydroxyl components. During the transition from magmatic to subsolidus hydrothermal conditions, pegmatitic topaz and vapor-phase topaz found in cavities and vugs are F-rich as well. The OH/(OH + F) ratio of topaz is commonly used as geothermometer for some strongly fractionated F-rich felsic igneous rocks and associated hydrothermal products. It seems to provide reasonable temperatures for transitional magmatic-hydrothermal/hydrothermal topaz, but for magmatic topaz, this geothermometer clearly conflicts with experimental data. Thus, a review of the chemical composition of topaz in relation to its formation temperature is undertaken for different geological provinces. This review indicates two composition fields, the first is that of hydrothermal topaz and topaz in vapor-phase cavities where the F-content increases with temperature, and the second field is that of magmatic topaz where this trend is reversed. Some data from: i) recent experiments in F-rich magmatic systems;ii) the distribution of fluorine among topaz and coexisting mica;and iii) chemical zoning within single grains of topaz at both magmatic and hydrothermal conditions, lend support to the hypothesis that fluorine concentrations in primary magmatic topaz increase with decreasing temperature. In addition, magmatic cooling tends to favor partitioning of fluorine into topaz rather than coexisting mica, whereas transitional magmatic-hydrotherma

关键词： Potassium  

摘要： This study aimed to evaluate the influence of storage (5 degrees C) and abuse (15 degrees C) temperatures and the addition of potassium sorbate (PS) on different quality attributes of modified atmosphere packaged (MAP) sliced Mozzarella cheese. It was observed that the temperature affected more significantly the cheese properties than the addition of PS in sliced MAP cheese. After 15 and 45 days of storage, the pH has decreased and the acidity has increased at 15 degrees C. The instrumental color parameters were practically temperature and PS independent. Empirical equations that estimate the kinetics of change of the quality attributes in terms of the temperature, storage time, and PS were derived. Regarding the microbiological quality, the psychrotrophic bacterial population continued to grow during the storage independently on the treatment. Depending on the treatment adopted, LAB, yeasts and molds, and Escherichia coli population decreased during the period of 75 days of storage. Practical applications The results obtained in the current study provide a quantitative evaluation of the influence of these independent variables on cheese quality. Empirical equations that estimate the rate of changes in the physicochemical and microbiological parameters were derived and can be used to evaluate the shelf life of sliced MAP Mozzarella cheese subjected to different storage conditions. Such information can help consumers and industry to optimize storage parameters of the product.

关键词： Lithium titanium oxide   Li4Ti5O12   Europium   Solid-state synthesis   Photoluminescent material   Spinel  

摘要： In this work we report our recent efforts on the investigation of the compositional and structural features of series of nanocrystalline Li4Ti5O12 (LTO) doped with Eu3+ ions powders, which were synthesized in a high-energy ballmilling (HEBM) process. Lithium carbonate, titanium and europium oxides were used as starting reagents. The ball-milled materials were turned into nanocrystalline powders due to the heating that was carried out in the air in the temperature range from 500 to 800 degrees C. The synthesized LTO doped with Eu3+ powders were examined by a number of physicochemical techniques: X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), absorption and emission spectroscopy (photoluminescence and excitation spectra were recorded), diffuse reflection spectroscopy (UV-vis DRS), scanning electron (SEM), transmission (TEM) and atomic force (AFM) microscopy. Structural, morphological and photoluminescent properties were correlated and examined for the first time in this work. The obtained results suggest that LTO material doped with rare earth ions like europium could serve as a material for applications in optoelectmnic devices such as white light emitting diodes (WLEDs).