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Endocrine disruptive compounds are natural or anthropogenic environmental micropollutants that alter the function of the endocrine system ultimately damaging the metabolism. Bisphenol A (BPA) is the most common of these pollutants and it is often used in epoxy coatings and polycarbonates as a plasticizer. Therefore, monitoring BPA levels in different environments is very important and challenging. In recent years, an increasing number of BPA detection methods have been proposed. This article presents a critical review of aptamer-based electrochemical, fluorescence-based, colorimetric, and several other BPA detection platforms published in the last decade. Furthermore, a statistical evaluation has been made using principle component analysis showing analytical performance parameters do not create very different clusters. Comparisons to other BPA detection methods are also presented so that the reader has an overall literature overview. [ABSTRACT FROM AUTHOR]

A surface plasmon resonance-enhanced total internal reflection ellipsometric (SPRe-TIRE) aptasensor is reported for the determination of the carcinoembryonic antigen (CEA). A gold nanofilm-coated SF10 glass slide was modified with electrochemical diazonium salt reduction and gold nanoparticles (AuNPs) to form a sensor. Next, a specific aptamer for CEA was immobilized on the AuNPs via self-assembly. The platform was characterized by X-ray photoelectron spectroscopy, ellipsometry, and cyclic voltammetry for each step of the preparation of the sensor. CEA aptamers with different affinities were used. SPRe-TIRE employed total internal reflection geometry and AuNPs to enhance plasmon resonance for the sensitive and selective determination of CEA in human serum. The working range of the aptasensor was from 0.01 to 500 ng/mL with an optimum detection limit of 0.1 pg/mL. [ABSTRACT FROM AUTHOR]

Mechanical tests at sub‐micron scales using force microscopy are often used for the characterization of materials. Here we report the mechanical, tribologic, and morphological characterization of recycled polypropylene beads using force spectroscopy and lateral‐force microscopy. The compression‐elastic moduli calculated using the Hertzian model for polypropylene beads was between 0.448 ± 0.010 and 1.044 ± 0.057 GPa. The grain size analysis revealed a significant correlation between the grain size and measured compression‐elastic moduli. Friction‐maps of recycled polypropylene beads obtained using lateral‐force microscopy were also reported for 25 μm2 scanning areas. [ABSTRACT FROM AUTHOR]

In this study, it is aimed to improve the lubrication and anti‐wear characteristics of nanofluids produced by the distribution of silane‐modified graphene nanosheets into the base oil without any surfactant or dispersant. Nanofluids are among the hottest research topics currently studied in the literature due to their interesting thermal and rheological properties. Graphene nanosheet with unique physicochemical properties is a good alternative as a nanofluid component and a lubricant. In this study, the behavior of nanofluidic films on the material was investigated by using scanning probe techniques, phase‐contrast microscopy, and friction force microscopy techniques. Due to stick–slip behavior and rheological properties that are dominant in the studied ranges, problems were encountered in performing tribological analyzes with friction force microscopy. On the other hand, these results have been beneficial in determining tribological factors in nanoscale. The presented nanofluids showed non‐Newtonian behavior at high concentrations and shear rates and shown an improved tribological performance up to 43% in friction coefficient, 91% in wear, and 46% in thermal conductivity compared to the base oil. [ABSTRACT FROM AUTHOR]

BACKGROUND Residual antibiotics taken along with food consumed through the food chain are the main cause of the super‐bacteria and may damage organs such as liver and kidney. Therefore, monitoring residual antibiotic levels of products in the food chain is both important and a requirement. Maximum residual limits for kanamycin and neomycin are 150 ng mL−1 and 500 ng mL−1 respectively, which are challenging for most sensor platforms. In this paper, a novel method is presented for the determination of antibiotics residues in animal‐derived foods. RESULTS: Aptamer‐based kanamycin and neomycin biosensors based on the spectroscopic ellipsometer and the surface plasmon resonance‐enhanced total internal reflection ellipsometer methods as transducing element were developed. Detection limits of both sensor platforms were in the 0.1–1 nmol L−1 ranges, and the detection range was between the detection limit and 1000 nmol L−1. CONCLUSION: Both ellipsometry‐based aptasensors can be used as an alternative to the existing enzyme‐linked immunosorbent assay‐based method in terms of assay time (10 min), detection limit (0.22 ng mL−1 for neomycin and 0.048 ng mL−1 for kanamycin), and detection range. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study, we synthesized poly (vinyl acetate-co-divinyl benzene) microspheres with various monomer/cross-linker contents for oral/topical sustained drug release applications and determined the micromechanical properties by nanoindentation. Compression elastic moduli of materials were calculated by using the limited depth of indentation according to Hertz elastic deformation model and presented as the histogram of multiple data. In terms of drug release practices, poly (VAc-co-DVB) microspheres with a high DVB content, especially in topical applications, are expected to carry drugs under mechanical stresses of less than 1.0 GPa. [ABSTRACT FROM AUTHOR]

ABSTRACT Cottonseed oil is consumed either in raw state or after refining, which enables it to acquire the characteristics such as neutral taste and odor, limpidity, light color, oxidation stability to oxidation, and for it to be used for frying. Refining comprises several strategies including bleaching, which involves the fixation of beta-carotene, the pigment that is responsible for the red color of cottonseed oils, on a solid support generally known as bleaching earth. In this work, possible application of locally available clay (Ordu, Turkey) as bleaching earth was investigated for cottonseed oil refining. Raw clay was activated via various treatment methods including acid activation, cation treatment and thermal treatment. Structural changes caused by acid activation were characterized using Fourier transform infrared spectroscopy, differential thermal analysis, N2 adsorption (BET surface area), X-ray fluorescence and scanning electron microscopy. Bleaching capacities of the treated clays were also determined spectrophotometrically. Bleaching efficiency was increased from 3 (raw clay) to 23% by H2SO4 activation and to 34% by Al3+ and heat treatment. However, commercial clay's efficiency was 32%. Tetrahedral destruction with proton attack was higher in HCl solution than H2SO4 solution, resulting in collapse in micropores. Bleaching efficiency increment using H2SO4 was higher than that of HCl. PRACTICAL APPLICATIONS It is important to reduce color in oils of low quality by cheap and appropriate adsorbent instead of expensive commercial earths. Activationconditions differ from one clay to another. In this study, several activation methods were applied and possible mechanisms relating to bleaching efficiency improvement were also investigated. [ABSTRACT FROM AUTHOR]