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关键词： Riboflavin   Photosensitizers   Adhesion   Antibacterial  

摘要： Purpose: To assess the micro-tensile bond strength (mu-TBS), degree of conversion, and antimicrobial capacity of modified dentin adhesive using riboflavin photoinitiators. Materials and methods: Three groups of adhesives (control;0.1 % riboflavin-PDT and 0.5 % riboflavin PDT) were prepared and tested on 70 sound molar teeth. Fourier-transformed infrared spectroscopy (FTIR) was performed for riboflavin and riboflavin-modified adhesives to calculate the degree of conversion. Contact angle measurement was performed by dropping a 5 mu L droplet of the adhesives onto polished dentin disk. For mu-TBS testing, the dentin beams were fixed on a micro-tensile tester and were loaded in tension at a cross-head speed of 1 mm per min until fracture. The viability of Streptococcus mutans biofilm was tested using MTT assay. Results: The spectrum at 1728 cm-1 indicates C=O stretching frequency of riboflavin. The groups control and 0.1 % riboflavin PDT showed the highest degree of conversion followed by lowest degree of conversion of 0.5 % riboflavin adhesive after PDT. The control adhesive exhibited the highest contact angle over the dentin surface compared to the riboflavin-modified adhesive groups (p < 0.05). The lowest contact angle was observed for 0.1 % riboflavin that showed increased permeability of the adhesive onto the dentin surface (p < 0.05). The variables of immediate bonding (F =12.328, p = 0.000) and ageing in artificial saliva (F = 41.559, p = 0.000) significantly affected the bond strength. For aged mu-TBS testing, the scores for 0.1 % riboflavin PDT was significantly higher as compared to the 0.5 % riboflavin PDT samples. The MTT resulted in a lower S. mutans viability for 0.5 % riboflavin PDT compared to 0.1 % riboflavin PDT and control adhesive (p < 0.05), irrespective of any time point, that is, after 24 h and 30 days ageing. Conclusions: The addition of riboflavin as photosensitizer in dentin adhesive demonstrated higher bond strength, excellent antimicrobial c

关键词： Chemical reactivity   Zeta potential   Piezoelectricity   Shearing   Intracrystalline deformation   Dislocation density   Quartz  

摘要： Chemical reactivity, grindability and zeta potential have been measured and correlated for three variably deformed quartz varieties from three different areas. Results show that there is a strong positive correlation between lattice imperfections and the measured physico-chemical and electrical properties of the three varieties. The highly deformed blue-grey quartz variety records the highest dissolution, grindability and surface electric charges compared to the less deformed milky and rose varieties. Microfabric study supported with XRD results show that the shear-related blue-grey variety exhibits a very strong intracrystalline deformation and high dislocation density indicative of low to intermediate grade conditions. The other two varieties, on the other hand, exhibit deformation features and lower dislocation densities pointing to a much lower grade. The higher chemical reactivity of the blue-grey quartz can be attributed in part to the morphological modifications the shearing creates within the quartz tetrahedra, and to the piezoelectric effect. Such modifications facilitate breaking the Si-O bonds, and lower the activation energy required to initiate the reaction between the silicon ions and the hydroxyl group. Piezoelectricity increases the electric potential across the crystal-liquid interface and hence setting the stage for the chemical reactions. The doubled value of zeta potential of the blue-grey quartz relative to the other two varieties opens the discussion of whether the inherited paleo-piezoelectricity of deformed quartz may enhance and play a significant role in the process of quartz dissolution or not.

关键词： Acid hydrolysis   Succination   Achira starch   Pasting properties  

摘要： The aim of this study was to evaluate the effect of acid hydrolysis and succination upon single and a combination of both of them as a dual modification on the morphological, structural, thermal, and pasting profile of the achira starch in order to expand its potential food applications. The surface of achira starch granules was eroded with acid hydrolysis, while the succination resulted in the formation of pores or cavities, having a slight impact on the crystallinity and the gelatinization enthalpy. Succinated starch presented the lowest transition temperatures (To = 60.29 degrees C, Tp = 65.03 degrees C and Te = 69.86 degrees C) compared to other starches in this study. The succination increased the final viscosity (3808 cp) when compared with the native starch (3114 cp), while acid hydrolysis resulted in a decreased value (735 cp). These are desirable properties for its possible use as an additive in bakery industry processes.

关键词： Textures  

摘要： The effects of quince seed mucilage powder (QSMP) on the physicochemical, microbiological, textural and sensory characteristics of yoghurts were evaluated. Incorporation of QSMP at different levels (0.05-0.2%) accelerated Lactobacillus bulgaricus growth. QSMP-yoghurts had lower syneresis;addition of QSMP at 0.15% and 0.2% prevented syneresis completely. Highest apparent viscosity values were obtained with 0.05% QSMP followed by 0.1%;however, 0.15% and 0.2% QSMP addition caused a significant (p < 0.05) decrease in viscosity. Yoghurts with QSMP showed lower firmness, consistency and cohesiveness values compared with the plain yoghurt. Microstructure analysis showed the casein network of the yoghurts with 0.15% and 0.2% QSMP was less compact and cohesive, with a thinner gel structure than that of other yoghurts. QSMP addition at levels of 0.05% and 0.1% was more acceptable to panellists in terms of flavour, odour and mouthfeel and addition higher than these levels caused a decrease in sensory attribute scores. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Complex fluid   Electroosmotic flow   Asymmetric charge   Asymptotic analysis   OpenFoam simulations  

摘要： We report a study on the micro-confined electroosmotic flow of an Oldroyd-B fluid over a surface having asymmetric charge modulation. We have employed a combination of regular and matched asymptotic expansion to obtain the analytical solution. We have also carried out a full numerical simulation of the physicochemical problem in order to assess the full parameter space of the problem. The analytical solution is shown to be in excellent agreement with the full numerical solution in the limiting conditions of thin electrical double layers and weakly viscoelastic fluids. We have used these solutions to describe the complex fluid flow pattern and the modified electroosmotic slip velocity. We have also highlighted the alteration in the net volumetric throughput and ionic current. We have subsequently presented the numerical solutions for the velocity field, flow rates, and streaming current by varying the physicochemical conditions at the surface and viscoelastic properties of the fluid. We report an augmentation in the electroosmotic slip velocity with the increase in relative strength. The symmetry breaking of flow and stress distributions are shown to affect the net-throughput and streaming current, which is indicative of the combined effect of phase angle, magnitude of charge distribution, and the fluid viscoelasticity. We have shown that the thickness of electrical double layer considerably affects the net-throughput and streaming current generation in the microchannel. Our results hold the key towards understanding the complex bio-fluid transport in a microchannel utilizing the electric field in the presence of non-uniform surface charge distribution.

关键词： Silicotungstic acid   Graphene oxide   Poly-o-phenylenediamine   Modification  

摘要： The methods of silicotungstic acid (SiW) immobilization on conducting substrates were studied. For SiW immobilization by codeposition, poly-o-phenylenediamine (PPD) redox polymer was used. The most effective codeposition of SiW and PPD was demonstrated on a graphene oxide (GO) film. Meanwhile, GO is reduced to form RGO-PPD-SiW electroactive composite. The structure of the novel material was evidenced by cyclic voltammetry and IR and Raman spectra. PPD-SiW and RGO-PPD-SiW composites were studied by impedance spectroscopy, where an equivalent circuit was proposed. Film resistance R-f was shown to decrease in the series of PPD -> RGO-PPD -> RGO-PPD-SiW. Further, RGO-PPD-SiW has better transfer properties (bulk film diffusion rate). This enabled suggesting that the composite has better electrocatalytic properties than PPD and RGO-PPD as was evidenced for example of [Fe(CN)(6)](4-/3-) redox transfer on the electrode coated with the novel material.

关键词： Micronization techniques   Grinding   Supercritical fluid   Homogenization   Microfluidization   Electrospraying  

摘要： Micronization is a mechanical and high shearing operation to downsize the particles of food material to the micron range. Conventionally micronization techniques were employed in pharmaceutical industries but in recent decades various studies have revealed its immense potential in food industries. This article reveals remarkable changes brought by micronization techniques in the food matrix. Size reduction to micron size boosts functional properties and physicochemical properties like water holding capacity, swelling capacity, solubility and antioxidant capacity. It also helps in preserving food by exposing the antimicrobial compounds on the surface or by inactivating microbes or by inhibiting enzymes thus improving the food stability. Micronization delayed retrogradation, induced gelatinization, reduced syneresis, decreased fermentation time, produced stable products and improved dissolution rate. These unique changes were found due to decrease in particle size and increase in surface area. Micronization by grinding, homogenizing, electrospraying and solvent-less micronization by supercritical fluid has been uniquely worked upon for the readers and researchers to have quick glance over recent trends and innovation. This review also details on principles, effective parameters, particle size, major outcomes, advantages and disadvantages of each micronizing technique.

关键词： Electron beam irradiation   Municipal excess sludge   Land application  

摘要： This work detailed the characteristics of municipal excess sludge irradiated by an electron beam for land application. From 5 kGy to 20 kGy, the release of soluble organic matter, nitrogen, and phosphorus substances in the sludge extract were markedly improved, and they exhibited different radiation susceptibility to free radicals and molecular products of the electron beam irradiation. The results indicated that, with the same sludge thickness, both irradiation products can efficiently react with organic matters. A further irradiation effect was caused majorly by molecular products, and an unsuitable thickness can produce a negative irradiation effect. Moreover, although an increased dose can cause an increase of Cu and Zn ions in the extract, the Cd and Pb contents were reduced by 35.71% and 20.97%, respectively, after 20 kGy of irradiation. In addition, the result of Fourier transform infrared spectra suggested that the electron beam irradiation has a significant impact on the organic matter in the sludge.

关键词： Honey   Ethiopia   Amhara region   Physicochemical parameters   Quality   Geographical origin  

摘要： The knowledge of the physicochemical properties of honey from different botanical and geographical origins is important to identify the honey with better quality. Accordingly, the Amhara region of Ethiopia is producing honey of different quality for the local and export market. Thus, the study was aimed at estimating the quality and developing a chemometric model for geographical origin classification of the region's honey based on its physicochemical parameters. A total of 47 honey samples were collected from 7 administrative zones (East Gojjam, West Gojjam, Awi, South Gondar, South Wollo, North Wollo and Wag Himera zones) of three major provinces (Gojjam, Gondar and Wollo) of the region. Eight physicochemical parameters of the honey samples were determined using internationally accepted standard methods. In view of that, the average values of the studied physicochemical parameters at each administrative zone were in the range of 16.06-18.51, 0.26-0.60, 61.45-71.41 and 2.96-4.73 g/100 g of honey for moisture content, ash content, total reducing sugar and apparent sucrose content respectively. In addition, pH (3.85-4.23), free acidity (26.39-37.80 meq/kg), electrical conductivity (33.37-63.43 mu S/cm) and HMF (3.88-8.50 mg/kg) were determined in the studied samples. Based on these values the region's honey was in a good quality that meets the national and international standard limits. In the PCA model, the first three principal components explained about 69.14% of the total variations and the LDA model had an average of 80.85% discrimination power. The LDA model was checked by cross-validation method and 100% of samples in the validation set were correctly classified by the model. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.

关键词： Biological indices   Freshwater   Macroinvertebrates   Organic pollution   Seasonal effect  

摘要： Although the macroinvertebrates have been widely used as bio-indicator for river water quality assessment in developed countries, its application is new in Iran and data on the health status of the most ecologically important rivers in Iran is scarce. The present study aimed at monitoring and assessing the ecological quality of Aghlagan river, northwest of Iran, using integrated physicochemical-biological approaches. A total of 14,423 samplings were carried out from the headwater to downstream sites at four stations (S1, 2, 3, 4) by a Surber sampler (30 cm x 30 cm) from June 2018 to April 2019. The results obtained from macroinvertebrate biotic index revealed that the genera of Gammarus (Amphipoda) and Baetis (Ephemeroptera) were the most abundant in all seasons. The PAST software was applied to analyze the diversity indices (Shannon-Weiner diversity, Evenness, and Simpson indices). Based on the cluster analysis, S3 established the least similarity to other stations. The average frequency of each macroinvertebrate species was determined by one-factor analysis of similarities (ANOSIM). In accordance with canonical correspondence analysis (CCA), temperature and phosphate were found as the dominant factors effecting the macroinvertebrate assemblage and distribution. Moreover, the results obtained from the biological indices concluded very good quality of S4 by Helsinhoff and EPT indices and fair quality using BMWP index. The data on the macrobenthos assemblage and dynamics in the Aghlagan river across a hydraulic gradient provided useful information on water management efforts that assist us to find sustainable solutions for the enhanced quality of the river by balancing environmental and human values.