Influence of the ER,CR:YSGG laser and different irrigation methods on push-out bond strength of fiber post

Er,Cr:YSGG lasers are currently being investigated for disinfecting the root canal treatment. The aim of this study was to compare the effects of various irrigation protocols on push-out bond strength of fiber posts. Fifty maxillary anterior teeth were divided into five groups (n = 10) according to the protocol that applied into the post space. Group-1: distilled water, Group-2: 5% NaOCl, Group-3: 2% CHX, Group-4: Er,Cr:YSGG laser (1.5 W, 20 Hz, 85 air, 75 water, 26.7 J/cm²), Group-5: Er,Cr:YSGG laser (1.25 W, 50 Hz, 34 air, 24 water, 12.7 J/cm²). Fiber posts were cemented with resin cement. The remaining part of the root, three slices were obtained from each specimen and push-out test was performed. One-way ANOVA and Duncan’s test at a 5% level of significance were used for the statistical analysis. Post space irradiation with Er,Cr:YSGG laser (1.5 W 20 Hz, 85 air, 75 water, 26.7 J/cm²) increases push-out bond strength of fiber post to root canal dentin. Further investigations are needed to establish and optimize ER,Cr:YSGG laser parameters to increase the push-out bond strength of fiber posts.     

The evaluation of procedures for dyeing silk with buckthorn and walloon oak on the basis of colour changes and fastness characteristics

In this study, silk fabric samples were dyed according to various procedures with buckthorn (Rhamnus petiolaris Boiss) and walloon oak (Quercus ithaburensis Decaisne) extracts. Reversed‐phase high‐performance liquid chromatography with diode‐array detection was utilised for the identification of dyes present in the dyed silk fabrics and the plant extracts. The extraction of dyes was carried out with a hydrochloric acid/methanol/water (2:1:1; v/v/v) mixture. The colour coordinates of the silk fabrics were measured, and the rubbing, wash and light fastness properties of the dyed silk materials were determined and are discussed.     

Optimization of the enzymatic production of isoamyl acetate with novozym 435 from candida antarctica

In this study the production of isoamyl acetate by esterification of isoamyl alcohol and acetic acid was carried out using immobilized C . antarctica lipase (Novozym 435) as a catalyst without any organic solvent. The esterification yield was optimized with response surface methodology. This method was used with four parameters to evaluate the effects of important variables on the esterification yield. The parameters are acid/alcohol mole ratio (0.2-0.8), enzyme amount (4-12%, w/w), temperature (30-50 °C), and reaction time (4-8 hr). It was found that the most effective parameter was acid/alcohol mole ratio. As acid/alcohol mole ratio increased at any given reaction time and amount of enzyme, ester concentration, C p (mmol ester/g mixture), increased up to an acid/alcohol mole ratio of 0.7 and thereafter decreased. The model indicated the optimum conditions for maximum esterification (3.45 mmol ester/g mixture) in the acid/alcohol mole ratio of 0.52 for 8.15% enzyme at 43.2 °C and after 5.27 hr, which were in good agreement with the experimental value (3.5 mmol ester/g mixture).     

Diffusion coefficients and phase equilibria of carbon dioxide–ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system

This article presents the mutual diffusion coefficients of a carbon dioxide–ionic liquid, [bmim][PF₆], system at temperatures of 313.15 and 323.15 K and pressures of 5 and 8 MPa. In order to estimate the diffusion coefficients, we have carried out experiments to find time-dependent carbon dioxide solubilities in the ionic liquid and then fit a transport model to the data. In a system containing high pressure carbon dioxide and ionic liquid, carbon dioxide dissolves in the liquid until its equilibrium mole fraction is reached. During this process, the position of the liquid–vapour interface and the density of the liquid phase change. To account for the variation in liquid density, an equation fit to the experimental density data is included in the transport model. To track the moving interface, the volume-of-fluid method is used. The diffusivities at dilute concentration and at thermodynamic phase equilibrium are determined and compared with the literature values and those obtained from correlations.     

The effect of substrate on the composition of polyhydroxyalkanoates in enhanced biological phosphorus removal

This paper primarily evaluates the effect of external substrate type on the composition of polyhydroxyalkanoates in enhanced biological phosphorus removal (EBPR). Two sets of sequencing batch reactors (SBRs) are operated for this purpose, one with acetate and the other with propionate as the sole carbon source at different influent COD/phosphate ratios in the range 6.7–20 mgCOD mg^?1P. Results indicate that propionate is a more efficient substrate for EBPR, enabling total phosphate removal regardless of the change in COD/phosphate ratio. Total polyhydroxyalkanoates formation of 267–291 mgCOD L^?1 with a slight increase at higher influent phosphorus levels is observed for acetate experiments, and a slightly lower level of 250–280 mgCOD L^?1, with a similar trend for propionate experiments. The volatile fatty acid type and composition in the influent induces a significant difference in the polyhydroxyalkanoates composition of the two sets of activated sludge sustained in corresponding SBR systems. Propionate is mostly stored as 3‐hydroxy‐2‐methylvalerate and polyhydroxyvalerate, while acetate is stored as polyhydroxybutyrate. The P uptake rate in SBRs fed with propionate is considerably higher than that in the acetate reactors. Parallel batch experiments yield different results, especially for systems fed with acetate, indicating that the enzymatic system to metabolize propionate is not rapidly established, always yielding a dominant polyhydroxybutyrate fraction in the generated polyhydroxyalkanoates regardless of the level of propionate in the feed. Copyright © 2007 Society of Chemical Industry     

Catalyst incorporation at defects during nanowire growth

Scanning and transmission electron microscopy was used to correlate the structure of planar defects with the prevalence of Au catalyst atom incorporation in Si nanowires. Site-specific high-resolution imaging along orthogonal zone axes, enabled by advances in focused ion beam cross sectioning, reveals substantial incorporation of catalyst atoms at grain boundaries in <110> oriented nanowires. In contrast, (111) stacking faults that generate new polytypes in <112> oriented nanowires do not show preferential catalyst incorporation. Tomographic reconstruction of the catalyst-nanowire interface is used to suggest criteria for the stability of planar defects that trap impurity atoms in catalyst-mediated nanowires.     

Natural ink production and printability studies for smart food packaging

Versatile smart packages provide information on the freshness of the content and help protect the content from microorganisms. In this sense, in this study both natural antimicrobial properties and pH sensitive natural dyes were obtained from red beet. Inks were prepared and printed using this dye and their suitability for smart packaging was investigated. For this purpose, red beet was cut into small sizes and mixed separately in ethanol and water (1:2) at 200 rpm. The betaine dye was taken up in solvent. These solvents were removed with evaporator and precipitated with centrifugation and dried in a vacuum oven. The chemical structure of the obtained dye was illuminated by Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR). The color character was determined by UV spectroscopy. Pink colored natural ink was produced by using ink varnish with carboxymethyl cellulose polymer and solid dye. Screen printing was made with this ink and the color, gloss, and lightfastness characters of prints were examined. Antimicrobial effects of the obtained prints were measured against Staphylococcus aureus and Escherichia coli. Mordanting studies were performed with (KAl[SO₄]₂.12H₂O) and change in color character was measured. The prints produced using the red beet extract have a yellow-orange color in the basic state; in acid cases it was determined to have a pink-purple color. In addition, it has been found that the ink prints obtained from red beet have antimicrobial properties against bacteria. Results prove that produced samples have good antimicrobial, pH indicator, and printability properties. This colorant can be used in smart food packaging.     

Voltammetric characterization of selective potassium ion transfer across micro-water/1,2-dichloroethane interface facilitated by a novel calix[4]arene derivative

In this study, transfer reactions of alkali and alkaline-earth metal ions across a micro-water/1,2-dichloroethane (1,2-DCE) interface facilitated by a novel calix[4]arene derivative, 5,11,17,23-tetra-tert-butyl-25,27-bis(2′amino-methylpyridine)-26,28-dihydroxy calix[4]arene (APHC4), were investigated by cyclic and differential pulse voltammetry techniques. Well-defined voltammetric behavior was obtained only for K⁺ ion among the used metal ions. The electrochemical data were used to determine the stoichiometry and the appropriate association constant of the occurring complex between K⁺ ion and APHC4. The obtained steady-state voltammograms indicated that the facilitated transfer process occurs with a TIC/TID mechanism according to 1:1 stoichiometry. The logarithm of the association constant () of K(APHC4)⁺ complex in the DCE phase was calculated to be 6.32. Also, the availability of the facilitated transfer for the design of an amperometric screening sensor for K⁺ ion was evaluated in the range of 50–500 μmol dm⁻³.