Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content

Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg−1 of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1:1 salt to IL molar ratio, equivalent to 3.2 mol kg−1 of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications.

The microstructure and physicochemical properties of probiotic buffalo yoghurt during fermentation and storage: a comparison with bovine yoghurt

The physicochemical and rheological properties of yoghurt made from unstandardised unhomogenised buffalo milk were investigated during fermentation and 28 days of storage and compared to the properties of yoghurt made from homogenised fortified bovine milk. A number of differences observed in the gel network can be linked to differences in milk composition. The microstructure of buffalo yoghurt, as assessed by confocal laser scanning microscopy (CLSM) and cryo scanning electron microscopy (cryo-SEM), was interrupted by large fat globules and featured more serum pores. These fat globules have a lower surface area and bind less protein than the homogenised fat globules in bovine milk. These microstructural differences likely lead to the higher syneresis observed for buffalo yoghurt with an increase from 17.4 % (w/w) to 19.7 % (w/w) in the weight of whey generated at days 1 and 28 of the storage. The higher concentration of total calcium in buffalo milk resulted in the release of more ionic calcium during fermentation. Gelation was also slower but the strength of the two gels was similar due to similar protein and total solids concentrations. Buffalo yoghurt was more viscous, less able to recover from deformation and less Newtonian than bovine yoghurt with a thixotropy of 3,035 Pa.s-1 measured for buffalo yoghurt at the end of the storage, at least four times higher than the thixotropy of bovine yoghurt. While the titratable acidity, lactose consumption and changes in organic acid concentrations were similar, differences were recorded in the viability of probiotic bacteria with a lower viability of Lactobacillus acidophilus of 5.17 log (CFU/g) recorded for buffalo yoghurt at day 28 of the storage. Our results show that factors other than the total solids content and protein concentration of milk affect the structural properties of yoghurt. They also illustrate the physicochemical reasons why buffalo and bovine yoghurt are reported to have different sensory properties and provide insight into how compositional changes can be used to alter the microstructure and properties of dairy products. © 2013 Springer Science+Business Media New York.

Effect of cosurfactant on the supramolecular structure and physicochemical properties of non-ionic biocompatible microemulsions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variability of physicochemical properties of an epoxy resin sealer taken from different parts of the same tube

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Physicochemical properties of endodontic sealers of different bases

Objective: To assess the setting time (ST), flow (FL), radiopacity (RD), solubility (SB) and dimensional change following setting (DC) of different sealers (AH Plus (R), Polifil, Apexit Plus (R), Sealapex (R), Endomethasone (R) and Endofill (R)) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. Material and methods: Five samples of each material were used for each test. For ST, cast rings were filled with sealers and tested with a Gillmore needle. For FL, the sealer was placed on a glass plate. After 180 s, another plate with 20 g and a load of 100 g were applied on the material, and the diameters of the discs formed were measured. In RD, circular molds were filled with the sealers, radiographed and analyzed using Digora software. For SB, circular molds were filled with the sealers, a nylon thread was placed inside the material and another glass plate was positioned on the set, pressed and stored at 37 degrees C. Samples were weighed, placed in water, dried and reweighed. The water used for SB was analyzed by atomic absorption spectrometry. For DC, circular molds were filled with the sealers, covered by glass plates and stored at 37 degrees C. Samples were measured and stored in water for 30 days. After this period, they were dryed and measured again. Results: Regarding ST, AH Plus (R), Apexit (R) and Endofil (R) sealers are in accordance with ANSI/ADA standards. Endomethasone's manufacturer did not mention the ST; Polifil is an experimental sealer and Sealapex (R) did not set. Considering RD, SB and DC, all sealers were in accordance with ANSI/ADA. The spectrometric analysis showed that a significant amount of K+ and Zn2(+) ions was released from Apexit Plus (R) and Endofill (R), respectively. Conclusion: Except for DC, all other physicochemical properties of the tested sealers conformed to ANSI/ADA requirements.

Purification and physicochemical properties of a ribonuclease produced by Aspergillus flavipes (IZ : 1501)

A RNase of Aspergillus flavipes (IZ:1501) was purified from culture medium by chromatography on DEAE-cellulose and Sephadex G50 columns, after 96 h of cultivation. The molecular weight of the RNase was estimated to be 15 kD by gel filtration using Sephadex G100, and the optimum pH and temperature were 4.0 and 55 degrees C, respectively. Catalytic activity was inhibited by Hg2+, Ag+, Fe3+, Co2+ and Zn2+. The enzyme showed guanosine specificity producing only 3'-GMP from yeast RNA.

Effect of grape pre-drying and static pomace contact on physicochemical properties and sensory acceptance of Brazilian (Bordo and Isabel) red wines

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches

A hidrólise enzimática do amido pode fornecer informações importantes sobre sua estrutura granular. Amidos de mandioca, batata-doce, mandioquinha-salsa e batata foram hidrolisados por α-amilase bacteriana a 37 °C durante 48 horas, e algumas propriedades físico-químicas dos resíduos da hidrólise foram determinadas. O amido de mandioca foi o mais suscetível à enzima com 20,9% de hidrólise, enquanto o amido de batata foi o mais resistente com 5,9%. O tamanho médio dos grânulos variou de 10,8 a 23,4 μm para os amidos de mandioquinha-salsa e batata, respectivamente. Amidos de mandioca e batata-doce apresentaram um padrão de difração de raio-X tipo A, enquanto os amidos de mandioquinha-salsa e batata mostraram padrão tipo B. Todos os amidos nativos mostraram superfície granular lisa e, após hidrólise, os amidos de mandioca, batata-doce e mandioquinha-salsa mostraram alguns grânulos bastante degradados, enquanto o amido de batata apresentou sutil sinal de degradação. O teor de amilose dos amidos diminuiu com a hidrólise para os amidos de mandioca, batata-doce e mandioquinha-salsa, permanecendo inalterado para o amido de batata. Como esperado, a viscosidade intrínseca e as propriedades de pasta diminuíram para todos os amidos hidrolisados. Não houve diferença significativa entre as propriedades térmicas dos amidos nativos e hidrolisados. Estes resultados sugeriram que a hidrólise ocorreu nas áreas cristalinas e amorfas dos grânulos. O padrão de difração do tipo B e o grande tamanho dos grânulos do amido de batata podem ter contribuído para a maior resistência deste amido à hidrólise.

Physicochemical properties of sildenafil citrate (Viagra) and sildenafil base

Sildenafil citrate (Viagra) [I] and sildenafil base [II] are easily and unequivocally characterized by a set of physicochemical methods that include X-ray diffractometry, infrared spectroscopy, and thermal analysis. Monoclinic lattice constants: [I]: a = 26.98 Angstrom; b = 11.95 Angstrom; c = 16.68 Angstrom; beta = 106.97degrees. [II]: a = 8.66 Angstrom; b = 34.27 Angstrom; c = 8.93 Angstrom; beta = 96.63'. Both compounds decompose at 189.4degreesC [I] and 251.9degreesC [II]. Densities and refractive indices are given. (C) 2003 Wiley-Liss, Inc.

Physicochemical properties and morphology of spongolite from Mato Grosso do Sul (Brazil)

The physicochemical properties and morphology of spongolite, a fibrous hollow material from Mato Grosso do Sul State (Brazil) have been studied. The results of thermal analysis, scanning electron microscopy (SEM), X-ray diffraction and NMR spectroscopy indicated that external and internal surfaces of silica spicules are covered by silica gel layers. The water evolved in the range 120-350degreesC is the result of silanol groups condensation to siloxane bonds. Total homogenization of the needles is achieved by heating spongolite over 900degreesC. This mineral may be considered as a natural composite material containing surface-immobilized reactive species. The presence of active silica gel layers opens the possibilities of attaching functional groups to spongolite surface. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Physicochemical properties of maize starch obtained from intermittent milling and dynamic steeping (IMDS) under various steeping conditions

Physicochemical properties of maize starch obtained under different steeping conditions by intermittent milling and dynamic steeping process (IMDS) were studied. Brazilian dent maize (hybrid XL 606) was milled using a 2x2x3 factorial experimental design with two lactic acid levels (0.0 and 0.55%, v/v), two SO2 levels (0.05 and 0.1%, w/v), and three temperatures (52, 60, and 68degreesC). Properties of starch obtained by conventional wet-milling process (36 hr at 52degreesC, 0.55% lactic acid, and 0.2% SO2) were used for comparison. Starch protein content and solubility increased with presence of lactic acid, while swelling power decreased. Higher SO2 concentration (0.1%) had the same effect as lactic acid on some properties. Steeping temperatures of 60 and 68degreesC increased solubility and most of the thermal properties but reduced swelling power, suggesting stronger starch annealing during IMDS at these temperatures. Some thermal changes on starch granules were visualized by scanning electron microscopy (SEM) at 60 and 68degreesC. Amylose content as well as pasting properties were affected by steeping factors and interactions. Starches from IMDS and conventional wet-milling processes were similar in most properties, indicating that IMDS provides starch with quality similar to that from conventional milling.

Production and physicochemical properties of resistant starch from hydrolysed wrinkled pea starch

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of different radiopacifying agents on the physicochemical properties of white portland cement and white mineral trioxide aggregate

Introduction: The aim of this study was to evaluate the pH, calcium ion release, setting time, and solubility of white mineral trioxide aggregate (WMTA) and white Portland cement (WPC) combined with the following radiopacifying agents: bismuth oxide (BO), calcium tungstate (CT), and zirconium oxide (ZO). Methods: Fifty acrylic teeth with root-end filling material were immersed in ultrapure water for measurement of pH and calcium release (atomic absorption spectrophotometry) at 3, 24, 72, and 168 hours. For evaluation of setting time, each material was analyzed according to the American Society for Testing and Materials guidelines 266/08. The solubility test was performed according to American National Standards Institute/American Dental Association specification no. 57/2000. Solubility, setting time, and pH values were compared by using analysis of variance and Tukey test, and the values of calcium release were compared by the Kruskal-Wallis and Miller tests. The significance level was set at 5%. Results: The pH and calcium release were higher at 3 and 24 hours. WPC was the material with the higher values for both properties. WMTA had the greatest solubility among all materials (P <.05). All radiopacifiers increased the setting time of WPC, and WMTA had the shortest setting time among all materials (P < .05). Conclusions: All materials released calcium ions. Except for WPC/CT at 168 hours, all materials promoted an alkaline pH. On the basis of the obtained results, ZO and CT can be considered as potential radiopacifying agents to be used in combination with Portland cement. Copyright © 2012 American Association of Endodontists.

Physicochemical properties of cassava starch oxidized by sodium hypochlorite

In this work, cassava starch was modified by treatment with sodium hypochlorite (NaClO) at different concentrations (0.8, 2.0 and 5.0 % of active chlorine) and selected physicochemical properties of the oxidized starches were investigated. The native and modified samples were evaluated considering moisture, carboxyl content, apparent viscosity, susceptibility to syneresis, mid-infrared spectroscopy and crystallinity index. The treatment with NaClO resulted in alterations in carboxyl content of the oxidized starches that increased with increasing concentration of the oxidant. Oxidized starches also showed higher susceptibility to syneresis, as assessed by the release of liquid during freezing and thawing. Apparent viscosity analysis showed decrease in peak viscosity of the oxidized starches. X-ray diffractograms showed that the oxidation influenced the extent of cassava starch relative crystallinity found to lie between 34.4 % (native) and 39.9 % (2.0 % active chlorine). The infrared spectra are sensitive to structural changes on starch macromolecules and presented characteristic peaks as C-O-C of the six carbon glucose ring absorbs at 1,150-1,085 cm -1 and due to axial deformation these bands changed with the crystal structure of the starch samples. © 2012 Association of Food Scientists & Technologists (India).