Determination of Some Endocrine-Disrupting Metals and Organochlorinated Pesticide Residues in Baby Food and Infant Formula in Turkish Markets

There is a paucity of data in respect of the nutritional quality of complementary foods for infants and young children aged between 6 and 12 months. In this study, we developed and validated an analytical method for determination of the endocrine-disrupting organochlorine pesticides (OCPs) and elements (As, Cd, and Pb) in infant formula and baby foods. Therefore, it found out the contamination level of the both OCPs and some trace metals (As, Cd, and Pb) in widely consumed infant formula and baby food in Turkey. Metal concentrations in baby foods and infant formula were determined by inductively coupled plasma mass spectrometry. Samples were digested with nitric acid and hydrogen peroxide in a microwave oven. Determination of 24 organochlorine pesticide residues in baby foods and infant formula was completed by using gas chromatography double mass spectrometry. QuEChERS extraction method was carried out in the sample preparation part. The analytical performance of the entire procedure, such as linearity, the detection of limit, limit of quantification, specificity/selectivity, recovery (%), and precision, were assessed. The recoveries ranged from 93% (As) to 100% (Pb) for elements 78–98% for organochlorine pesticide residues (OCPs) at 100 ng mL^?1. According to the results, lead, cadmium, and pesticides were not detected in any of the samples, while arsenic was detected in 16 samples.     

Raman Spectroscopic Barcode Use for Differentiation of Vegetable Oils and Determination of Their Major Fatty Acid Composition

In this study, differentiation of vegetable oils and determination of their major fatty acid (FA) composition were performed using Raman spectral barcoding approach. Samples from seven different sources (sunflower, corn, olive, canola, mustard, soybean and palm) were analyzed using Raman spectroscopy. Second derivative of the spectral data was utilized to generate unique barcodes of oils. Chemometric analyses, namely, principal component analysis (PCA) and partial least square (PLS) methods were used for data analysis. PCA was applied for classification of the samples according to the differences in their levels arising from their barcode data. A successful differentiation based on second derivative barcodes of Raman spectra (2D‐BRS) of vegetable oils was obtained. In addition, PLS method was applied on 2D‐BRS in order to determine the major FA composition of these samples. Coefficient of determination values for palmitic, stearic, oleic, linoleic, α‐linolenic, cis‐11 eicosenoic, erucic and nervonic acids were in the range of 0.970–0.989. Limit of detection and limit of quantification values were found to be satisfactory (0.09–8.09 and 0.30–26.95 % in oil) for these fatty acids . Advantages of both chemometric analysis and spectral barcoding approach have been utilized in the present study. Taking the second derivative of the Raman spectra has minimized background variability and sensitivity to intensity fluctuations. Spectral conversion to the barcodes has further increased the quality of information obtained from Raman spectra and also made it possible to improve the visualization of the data. Converting Raman spectra of oils into barcodes enables simpler presentation of the valuable information, and still allows further analysis such as classification of vegetable oils and prediction of their major fatty acids with high accuracy.     

Emulsifier‐free cationic latexes based on vinylbenzyl chloride and 2‐(dimethylamino)ethyl methacrylate with adjusted hydrophilic–hydrophobic properties

Functional emulsifier‐free cationic latexes based on styrenic monomer vinylbenzyl chloride (VBC) and acrylic monomer 2‐(dimethylamino)ethyl methacrylate (DMA) were successfully prepared with dual quaternary ammonium ions (36–63 mol %) on both monomer moieties in two‐stages. First, [2‐(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide monomer (DMA(C₁₆)), prepared via quaternization of DMA with 1‐bromohexadecane, was utilized as a comonomer (5–20%) as well as a surfactant in the emulsion polymerization of VBC. Next, the quaternization of chloromethyl groups in the VBC moiety in latex particles with trimethylamine and N,N‐dimethylhexadecylamine created a second type of quaternized sites on the latex particles. The percentages of the quaternary ammonium ions of the first‐stage latexes (P[VBC‐DMA(C₁₆‐x)]) and the second‐stage latexes (P[VBC(R)‐DMA(C₁₆‐x)]) were determined using bromide and chloride ion‐selective electrodes. The particles were characterized with a scanning electron microscope, Zetasizer, measuring water contact angles of their pellets. The polymer structure and the alkyl group length in their quaternary ammonium ions played an important role on the sizes, zeta potentials and hydrophilic–hydrophobic balances of the latexes. The water contact angles of the pellets of the latex particles varied from 50.3 to 109.6° depending on both the polymer structure and the alkyl group length. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42775.     

Effect of Dipping Temperature and Dipping Time on Drying Rate and Color Change of Grapes

Thompson seedless grapes (Vitis vinifera) were pretreated in potassium carbonate and ethyl oleate solutions for 1, 2, and 3 min at 30, 40, 50, and 60°C and dried in a convective air dryer at 60°C. The effect of dipping time and solution temperature on drying rate and color kinetics were investigated. Grapes dipped into the solution at 60°C for 2 and 3 min had the fastest drying rate. Among the seven semi theoretical models compared, the Midilli equation best described the drying curves of grapes for all dipping pretreatments. Color data were obtained using a machine vision system in CIE L*a*b* color space. Regardless of the dipping time and temperature applied, all raisins had varying degrees of brown coloring. At all dipping times and temperatures the highest R ² value was obtained for a* values, which followed zero-order reaction kinetics during drying.     

Surface-modified alumina nanoparticles-filled aramid fiber-reinforced epoxy nanocomposites: preparation and mechanical properties

Iranian Polymer Journal - Surface of Al2O3 nanoparticles was modified with a silane coupling agent, and aramid fiber-reinforced epoxy nanocomposites were produced using these particles. Three...     

Characterization of tributyrin hydrolysis by immobilized lipase on woolen cloth using conventional batch and novel spinning cloth disc reactors

Optimal loading and operating conditions for a new, superior immobilization of amano lipase from Pseudomonas fluorescens on woolen cloth were determined. The optimal enzyme loading was 46.8 mg g dry cloth⁻¹ with activity of 200 U. A batch reactor was used to characterize process conditions important to industrial application of the wool immobilized lipase. The optimal pH for immobilized lipase in tributyrin hydrolysis was 7, slightly lower than that of free lipase (pH 8). The optimal temperature for both free and immobilized lipase was 45 °C. The immobilized lipase was more stable to reuse than some other lipase immobilizations, maintaining 85% of its activity after 6 long term runs and 75.8% of the original activity after storage of 40 weeks at 4 °C. The thermal stability of lipase was improved by 2.4 times after immobilization. The thermal deactivation rate of immobilized lipase followed the Arrhenius law with E_d = 199 kJ mol⁻¹. The Michaelis–Menten constant (K_m) of the lipase increased from 1.63 mM to 4.48 mM after immobilization. The immobilized lipase was also successfully applied for tributyrin hydrolysis in a novel enzyme process intensification technology – the spinning cloth disc reactor (SCDR): conversion increased by around 13% under similar conditions compared to a conventional batch stirred tank reactor. The SCDR is therefore key to exploiting the advantages of the wool immobilized lipase developed in this work.     

Investigation of UV and I–V characteristics of high refractive index polymer thin film for optoelectronic applications

In this study, high refractive index polymer (HRIP) [poly(pentabromobenzyl methacrylate-co-glycidyl methacrylate)] was investigated to obtain its optical and electrical performance for optoelectronic applications. UV characteristics of the polymer in solution of tetrahydrofuran were obtained and optical band gap energy of the polymer was calculated as 3.8 eV. I–V characteristics of the polymer were investigated after HRIP thin film was prepared using spin coating technique. The electrical parameters such as barrier height Φ_Bo, ideality factor n and reverse saturation current I_o were extracted from the forward biasing I–V characteristics. At the same time, series resistance R_s and Φ_Bo were determined by using a modified Norde function combined with conventional forward I–V method.     

From a Non-Local Ambrosio-Tortorelli Phase Field to a Randomized Part Hierarchy Tree

In its most widespread imaging and vision applications, Ambrosio and Tortorelli (AT) phase field is a technical device for applying gradient descent to Mumford and Shah simultaneous segmentation and restoration functional or its extensions. As such, it forms a diffuse alternative to sharp interfaces or level sets and parametric techniques. The functionality of the AT field, however, is not limited to segmentation and restoration applications. We demonstrate the possibility of coding parts—features that are higher level than edges and boundaries—after incorporating higher level influences via distances and averages. The iteratively extracted parts using the level curves with double point singularities are organized as a proper binary tree. Inconsistencies due to non-generic configurations for level curves as well as due to visual changes such as occlusion are successfully handled once the tree is endowed with a probabilistic structure. As a proof of concept, we present (1) the most probable configurations from our randomized trees; and (2) correspondence matching results between illustrative shape pairs. The work is a significant step towards establishing exponentially decaying diffuse distance fields as bridges between low level visual processing and shape computations.     

Variation of part thickness and compaction pressure in vacuum infusion process

In vacuum infusion (VI), it is difficult to manufacture a composite part with small dimensional tolerances, since the thickness of the part changes during resin injection. This change of thickness is due to the effect of varying compaction pressure on the upper mold part, a vacuum bag. In this study, random fabric layers with an embedded core distribution medium is used. The thickness of the composite part and resin pressure are monitored using multiple dial gages and pressure transducers; the results are compared with the model developed by Correia et al. [Correia NC, Robitaille F, Long AC, Rudd CD, Simacek P, Advani SG. Analysis of the vacuum infusion molding process: I. Analytical formulation. Composites Part A: Applied Science and Manufacturing 26, 2005. p. 1645–1656]. To use this model, two material characteristics databases are constructed based on the process parameters: (i) the thickness of a dry/wet fabric preform at different compaction pressures, and (ii) the permeability of the preform at different thicknesses. The dry-compacted preform under vacuum is further compacted due to fiber settling in wet form after resin reaches there; the part thickens afterwards as the resin pressure increases locally. The realistic model solution can be achieved only if the compaction characterization experiments are performed in such a way that the fabric is dry during loading, and wet during unloading, as in the actual resin infusion process. The model results can be used to design the process parameters such as vacuum pressure and locations of injection and ventilation tubes so that the dimensional tolerances can be kept small.     

Quality Indices for Aluminum Alloy Castings: A Critical Review

Several indices are available in the literature to assess the structural quality of cast Al alloys, especially Al-7 pct Si-Mg alloys that are based on tensile test results. Some of these indices, most notably the one developed by Drouzy et al., provide a number that necessarily does not have a physical meaning, whereas the others are a measure of what fraction of the expected tensile performance is achieved. These indices are analyzed in depth, their similarities and shortcomings are discussed in detail, and recommendations are made.