Ion-Specific Interaction of Alumina Surfaces

There has been a long-standing question about the effect of the type of ionic species on the surface forces that is not considered in the classical Derjaguin–Landau–Vervey–Overbeek theory. Originating from the work of Hofmeister, the ion-specific interaction between particles has been known for a long time. Depending on the pH and oxide type, a direct or a reverse Hofmeister effect has been observed in colloidal suspensions at high salt concentrations. The origin of this effect is not well understood but is qualitatively taken into account in colloid science. From macroscopic behavior, it is predicted that alumina particles in LiCl solution attract each other more strongly than in CsCl solutions. If such an effect does exist, then force curves obtained using the colloid probe technique may detect the difference. Using chloride salts of the two end members of the Hofmeister series, namely Li⁺ and Cs⁺, stronger attraction in the LiCl electrolyte solution compared with the CsCl one was measured for the first time at the microlevel between alumina surfaces at pH=11.     

Modeling high-temperature stress-strain behavior of cast aluminum alloys

A modified two-state-variable unified constitutive model is presented to model the high-temperature stress-strain behavior of a 319 cast aluminum alloy with a T7 heat treatment. A systematic method is outlined, with which one can determine the material parameters used in the experimentally based model. The microstructural processes affecting the material behavior were identified using transmission electron microscopy and were consequently correlated to the model parameters. The stress-strain behavior was found to be dominated by the decomposition of the metastable θ′ precipitates within the dendrites and the subsequent coarsening of the θ phase, which was manifested through remarkable softening with cycling and time. The model was found to accurately simulate experimental stress-strain behavior such as strain-rate sensitivity, cyclic softening, aging effects, transient material behavior, and stress relaxation, in addition to capturing the main deformation mechanisms and microstructural changes as a function of temperature and inelastic strain rate.     

A comparison of clustering-based privacy-preserving collaborative filtering schemes

Privacy-preserving collaborative filtering (PPCF) methods designate extremely beneficial filtering skills without deeply jeopardizing privacy. However, they mostly suffer from scalability, sparsity, and accuracy problems. First, applying privacy measures introduces additional costs making scalability worse. Second, due to randomness for preserving privacy, quality of predictions diminishes. Third, with increasing number of products, sparsity becomes an issue for both CF and PPCF schemes.In this study, we first propose a content-based profiling (CBP) of users to overcome sparsity issues while performing clustering because the very sparse nature of rating profiles sometimes do not allow strong discrimination. To cope with scalability and accuracy problems of PPCF schemes, we then show how to apply k-means clustering (KMC), fuzzy c-means method (FCM), and self-organizing map (SOM) clustering to CF schemes while preserving users’ confidentiality. After presenting an evaluation of clustering-based methods in terms of privacy and supplementary costs, we carry out real data-based experiments to compare the clustering algorithms within and against traditional CF and PPCF approaches in terms of accuracy. Our empirical outcomes demonstrate that FCM achieves the best low cost performance compared to other methods due to its approximation-based model. The results also show that our privacy-preserving methods are able to offer precise predictions.     

Fully Automated Three-Dimensional Column-Switching SPE–FIA–HPLC System for the Characterization of Lipids by a Single Injection: Part I. Instrumental Design and Chemometric Approach to Assess the Effect of Experimental Settings on the Response of ELSD

This article presents the first application of fully automated three‐dimensional (3D) column‐switching SPE–FIA–HPLC system for the characterization of lipids by a single injection. The whole system was designed and set up by modifying Agilent 1200 Series HPLC system in our laboratory. By using this system, a complete separation profile of the oil samples was achieved in a very short time period by using single injections. This approach was applied on vegetable oils which contains a large number of relatively high‐class lipid components, such as TG, FFA, sterols, tocopherols, DG, ester and MG. In this part of the study, we focused on the optimization of evaporative light scattering detector (ELSD) by using an experimental design and RSM. Three experimental parameters were chosen as an independent variables which are the flow rate of mobile phase, nebulization temperature and evaporation temperature. A multivariate five level experimental design was used to establish a quadratic model as a functional relationship between the response values and independent variables. The optimal values of parameters were found to be a flow rate of 1.25 mL min^?1, nebulization temperature of 80 °C, and evaporation temperature of 40 °C. Regression analysis with an R² values indicated as a satisfactory correlation between the experimental and predicted values. ANOVA test results were also illustrate that the models can be successfully used to predict the optimum parameters of ELSD. Thus, the proposed system is suitable for a large number of applications including research and development of new quality control and characterization methods for vegetable oils.     

Compressible magnetorheological fluids

A novel compressible magnetorheological fluid (CMRF) has been synthesized with additives that provide compressibility to the fluid. This CMRF has been designed to provide an elastic component to a magnetorheological fluid (MRF) that can be used as a springless damper. CMRF provides controllable compressibility to the MRF. The controllability of the fluid is achieved by the use of magnetic particles and an external magnetic field, and the fluid is made compressible by the addition of suspended compressible polymer particles. The compressibility of the fluid has been characterized with force–displacement measurements. This CMRF has controllable off‐state viscosity and high shear yield stress. The incorporation of polymeric particles into the MRF also decreases the settling of iron particles and improves the redispersion of the fluid. To make the fluid more redispersible, the surface of the iron particles is coated with a high‐temperature fluorinated polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High‐performance filaments by melt spinning low viscosity nylon 6 using horizontal isothermal bath process

Several techniques and treatments have been developed for the production of high‐performance nylon‐6 fibers. The inherent problems of low productivity, high production cost, and high energy consumption, complexity of chemical reaction, mass transfer, and waste recovery systems make most of them inappropriate for industrial application. Horizontal isothermal bath (hIB) is an alternative ecofriendly simple treatment that can be used during melt spinning process for production of technical textile fibers. The efficacy of hIB in improving the mechanical properties of multifilament nylon‐6 yarn is studied in this research. The results showed that such treatment can increase the molecular orientation of the amorphous and crystalline functions up to 0.54 and 0.983, respectively, and raised both the amorphous isotropy and fiber birefringence by 67 and 45%, respectively. Hot drawing of the yarn at a very low draw ratio of 1.38, increased the tenacity and modulus up to 10 and 43.9 g/den, respectively, and decreased the elongation to 27%. POLYM. ENG. SCI., 55:2457–2464, 2015. © 2015 Society of Plastics Engineers     

Characterization of Turkish Olive Oils by Triacylglycerol Structures and Sterol Profiles

A characterization study of Turkish monovarietal olive oils using chemical variables such as fatty acid, sn‐2 fatty acid, triacylglycerol, and sterol composition is presented. A total of 101 samples of Olea europaea L. fruits from 18 cultivars were collected for two crop years from west, south, and southeast regions of Turkey. Olives were processed to oil and olive oil samples were evaluated for their triacylglycerol structures and sterol composition. Oleic acid content ranged from 60.15 to 80.46 % of total fatty acids and represented 70.90–89.02 % of sn‐2 position triacylglycerols. Major triglycerides of oil samples were triolein, palmitodiolein, dioleolinolein, palmitooleolinolein, dipalmitoolein, and stearodiolein. Triolein values were between 24.72 and 48.64 % and compatible with the fatty acid composition. Total sterol content varied from 1,145.32 to 2,211.77 mg/kg and Edremit yagl?k stood out because of its high sterol content. A one‐way analysis of variance revealed significant differences for variables among cultivars. Principle component analysis enabled the classification of common varieties on the basis of analytical data. Sterol composition achieved more relevant discrimination than fatty acid and triglyceride composition. Classification according to geographical origin was performed by discriminant analysis.     

New Options for Conversion of Vegetable Oils to Alternative Fuels

Biodiesel from transesterification of vegetable oils is an excellent alternative fuel. There is, however, a need to develop a direct process for conversion of vegetable oils into gasoline-competitive biodiesel and other petroleum products. Methyl esters of vegetable oils have several outstanding advantages among other new-renewable and clean engine fuel alternatives. The purpose of the transesterification process is to lower the viscosity of vegetable oil. Compared to No. 2 diesel fuel, all of the vegetable oils are much more viscous, whereas methyl esters of vegetable oils are slightly more viscous. The methyl esters are more volatile than those of the vegetable oils. Conversion of vegetable oils to useful fuels involves the pyrolysis and catalytic cracking of the oils into lower molecular products. Pyrolysis produces more biogasoline than biodiesel fuel. Soap pyrolysis products of vegetable oils can be used as alternative diesel engine fuel. The soaps obtained from the vegetable oils can be pyrolyzed into hydrocarbon-rich products. Zinc chloride catalyst contributed greatly to high amounts of hydrocarbons in the liquid product. The yield of ZnCl ₂ catalytic conversion of the soybean oil reached the maximum 79.9% at 660 K.     

Use of Fenton oxidation to improve the biodegradability of a pharmaceutical wastewater

The applicability of Fenton's oxidation to improve the biodegradability of a pharmaceutical wastewater to be treated biologically was investigated. The wastewater was originated from a factory producing a variety of pharmaceutical chemicals. Treatability studies were conducted under laboratory conditions with all chemicals (having COD varying from 900 to 7000 mg/L) produced in the factory in order to determine the operational conditions to utilize in the full-scale treatment plant. Optimum pH was determined as 3.5 and 7.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. For all chemicals, COD removal efficiency was highest when the molar ratio of H(2)O(2)/Fe(2+) was 150-250. At H(2)O(2)/Fe(2+) ratio of 155, 0.3M H(2)O(2) and 0.002 M Fe(2+), provided 45-65% COD removal. The wastewater treatment plant that employs Fenton oxidation followed by aerobic degradation in sequencing batch reactors (SBR), built after these treatability studies provided an overall COD removal efficiency of 98%, and compliance with the discharge limits. The efficiency of the Fenton's oxidation was around 45-50% and the efficiency in the SBR system which has two reactors each having a volume of 8m(3) and operated with a total cycle time of 1 day, was around 98%, regarding the COD removal.