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排序方式: 共有1058条查询结果,搜索用时 46 毫秒
101.
Felipe C. da Silva Carolina Rodrigues da Fonseca Severino Matias de Alencar Marcelo Thomazini Julio C. de Carvalho Balieiro Paola Pittia Carmen Sílvia Favaro-Trindade 《Food and Bioproducts Processing》2013,91(1):28-36
The aim of this work was to obtain propolis in a powder, alcohol-free, water-dispersed and shelf-stable form. Propolis extract was spray-dried using gum Arabic and octenyl succinic anhydride (OSA) starch as carriers in two different weight ratios (1:4 and 1:6). Spray-dried propolis samples were evaluated for morphology, moisture, water activity, water dispersibility, hygroscopicity, particle size, particle distribution, entrapping efficiency, stability, isotherms and antioxidant properties. The spray-drying process produced round particles with sizes ranging from 15 to 24 μm. This process preserved the antioxidant activity of propolis and also allowed propolis to be obtained in a powder form, which was stable during storage at room temperature, had low hygroscopicity and was highly dispersible in cold water. The application of this technology could increase the use of propolis in various industrial applications, such as an antimicrobial and as an antioxidant in food. 相似文献
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103.
Talita A. Comunian Ednelí S. Monterrey‐Quintero Marcelo Thomazini Julio C. C. Balieiro Pierpaolo Piccone Paola Pittia Carmen S. Favaro‐Trindade 《International Journal of Food Science & Technology》2011,46(6):1259-1265
The aim of this research was to study spray drying as potential action to protect chlorophyllide from environmental conditions for shelf‐life extension and characterisation of the powders. Six formulations were prepared with 7.5 and 10 g of carrier agents [gum Arabic (GA), maltodextrin (MA) and soybean protein isolate (SPI)]/100 mL of chlorophyllide solutions. The powders were evaluated for morphological characteristics (SEM), particle size, water activity, moisture, density, hygroscopicity, cold water solubility, sorption isotherms, colour and stability, during 90 days. All the powders were highly soluble, with solubility values around 97%. A significant lower hygroscopicity was observed for GA powders, whilst the lower Xm values obtained by GAB equation fitting of the sorption isotherms was observed for the 7.5 g MA/100 mL samples. All formulations, but the 1 (7.5 g SPI/100 mL of chlorophyllide), provided excellent stability to the chlorophyllide during 90 days of storage even at room temperature. 相似文献
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The solid state reaction Cu + Cu2+ → 2Cu+ in CsCuCl3 was studied at 499 K using a cell in which the Cu(II) sample was put between two copper discs. Mass changes, thickness of the product layer and the total electrical resistance of the cell were measured as a function of time, both with and without (spontaneous) applied voltage. 相似文献
106.
Pedro Peris-Lopez Julio C. Hernandez-Castro Juan M.E. Tapiador Tieyan Li Yingjiu Li 《Computer Networks》2010,54(9):1502-1508
In RFIDSec’08, Song proposed an ownership transfer scheme, which consists of an ownership transfer protocol and a secret update protocol [7]. The ownership transfer protocol is completely based on a mutual authentication protocol proposed in WiSec’08 [8]. In Rizomiliotis et al. (2009) [6], van Deursen and Radomirovic (2008), the first weaknesses to be identified (tag and server impersonation) were addressed and this paper completes the consideration of them all. We find that the mutual authentication protocol, and therefore the ownership transfer protocol, possesses certain weaknesses related to most of the security properties initially required in protocol design: tag information leakage, tag location tracking, and forward traceability. Moreover, the secret update protocol is not immune to de-synchronization attacks. 相似文献
107.
Julio Sevillano María Gracia Snchez-Alonso Javier Pizarro-Delgado María del Pilar Ramos-lvarez 《International journal of molecular sciences》2021,22(11)
Changes in lifestyle in developed countries have triggered the prevalence of obesity and type 2 diabetes mellitus (T2DM) in the latest years. Consequently, these metabolic diseases associated to insulin resistance, and the morbidity associated with them, accounts for enormous costs for the health systems. The best way to face this problem is to identify potential therapeutic targets and/or early biomarkers to help in the treatment and in the early detection. In the insulin receptor signaling cascade, the activities of protein tyrosine kinases and phosphatases are coordinated, thus, protein tyrosine kinases amplify the insulin signaling response, whereas phosphatases are required for the regulation of the rate and duration of that response. The focus of this review is to summarize the impact of transmembrane receptor protein tyrosine phosphatase (RPTPs) in the insulin signaling cascade and secretion, and their implication in metabolic diseases such as obesity and T2DM. 相似文献
108.
This report seeks to address the role of hydrogen bonding with Brønsted acids and bases in proton-coupled electron transfer (PCET) as it pertains to concerted or stepwise pathways of quinone (Q) and hydroquinone (QH2) electrochemistry. This study was performed using a series of techniques that included cyclic voltammetry (CV), digital simulations, computational chemistry and 1H NMR. Hydrogen bonding was inferred by a decrease in diffusion coefficient (D) values measured using a pulsed gradient echo- (PGE-) 1H NMR technique. Changes of 40.8% and 37.9% in D values were only noted after the addition of two equivalents of acetate to 1,4-hydroquinone (1,4-QH2) and catechol (1,2-QH2), respectively. In contrast, the D values for the addition of selected amines (pyridine, N,N-diisopropylethylamine and triethylamine) changed only 3.2% on average. Quantum mechanical calculations were conducted to determine the pKa of all quinoid species to serve as a starting point for the determination of equilibrium constants in voltammetric simulations. Simulations indicate that 1,4-benzoquinone undergoes stepwise electron-proton transfer upon addition of acetic acid, N-ethyldiisopropylammonium perchlorate and pyridinium nitrate and were simulated without the presence of hydrogen bonds. The QH2 compounds show stepwise proton-electron transfers after addition of the both the conjugate amines and acetate. 相似文献
109.
Surface deposition of paste or thickened tailings is increasing contemplated as an alternative to conventional slurry deposition. One important challenge in managing paste is to predict the evolving geometry of the tailings stack during deposition. This study dynamically images multilayer deposition of paste in flows in flume and axisymmetric flows. Each layer is left to self-weight consolidate for a day before the next layer is placed. It is found that both the steady-state profiles and the dynamic flows can be modelled as a Bingham fluid using equations developed from lubrication theory. Yield stress and viscosity were determined using rheometry and slump tests. It is shown that the yield stress obtained from the slump test may overestimate the yield stress of significance to flow deposition; namely that yield stress that characterizes when the tailings stop flowing. The lubrication theory equations show that the overall angle of a tailings deposit at steady-state is dependant on the scale of the flow, which may explain the discrepancy between laboratory flume angles and field angles noted in practice. 相似文献
110.