Positron Annihilation Studies of Modified Aluminide Coatings on Nickel and Nickel Superalloy

Russian Journal of Non-Ferrous Metals - Aluminide coatings deposited by CVD method on CMSX-4 superalloy, modified by palladium and zirconium or hafnium as well as non-modified and palladium...     

Polythiophene with ionophore substituent in the side chain

The article presents the method of the synthesis of sulfonated polythiophene derivative (PTMBSA) in aqueous medium by means of emulsion polymerization. The method applies potassium peroxydisulfate as initiator and sodium dodecyl sulfate as the surfactant. The structure and physicochemical properties have been analyzed. Resulting polymers were characterized via Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), thermogravimetric analysis, UV‐VIS, and electrochemical methods (e.g., cyclic voltammetric, current‐voltage characteristics, doping processes). Resulting polymer revealed mixed electronic and ionic conductivity having solid state maximum conductivity σ = 5.061 μS m^?1. It is four orders of magnitude higher than this of pristine polythiophene obtained by similar way. Presented results show that tested polymers are interesting and seem to be promising material for organic electronic applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44372.     

Molecular pincers: antibody-based homogeneous protein sensors

We describe here a new homogeneous antibody-based protein sensor design (molecular pincers) that allows rapid and sensitive detection of a specific protein in solution. In the presence of the target protein these sensors produce fluorescence signal derived from target-dependent annealing of short complementary fluorochrome-labeled oligonucleotides attached to a pair of target-specific antibodies via nanometer-scale flexible linkers. The sensors allow near-instantaneous detection of the target with sensitivity and specificity approaching that of enzyme-linked immunosorbent assay (ELISA) but requiring no sample manipulation other then the addition of the sample to the sensor mix. We used cardiac troponin I and C-reactive protein as the targets to validate these desirable properties of the sensors. Due to the availability of antibodies to thousands of interesting targets and the straightforward design blueprint of the sensors we expect their wide-ranging applications in research and medical diagnosis, especially when simplicity, high throughput, and short detection time are essential.     

Impact of Selected Chemical Characteristics of Cold-Pressed Oils on their Oxidative Stability Determined Using the Rancimat and Pressure Differential Scanning Calorimetry Method

In this study, 27 market and edible cold-pressed oils from 10 different oilseeds were analysed. Oxidative stability and the chemical composition of oils were evaluated. The oils were investigated for their primary quality, fatty acid composition, total phenolic content and antioxidant activity. Rancimat and pressure differential scanning calorimetry (PDSC) were used to assess oils oxidative stability. Principal component analysis (PCA) was conducted to determinate impact of selected chemical characteristics on tested oils’ oxidative stability in accelerated modes. PCA indicated that none of the chemical compounds correlated strongly with the oils’ oxidative stability determined by the Rancimat method. Correlation coefficients describing the impact of different chemical compounds on induction time determined using the Rancimat method were between r = ?0.54 (C18:3) to r = 0.62 (chlorophyll pigments). Oxidative stability of oils determined using the Rancimat and pressure differential scanning calorimetry (PDSC) were characterised by low correlation (r = 0.66). According to the statistical analyses, oils were divided into four groups, which depend on the method of oxidative stability evaluation did not differ.     

Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure’s effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/45 mg ENVI-Carb/900 mg MgSO₄, and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (>?20%), showing suppression or enhancement. Most recoveries were in the range of 70–120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg^?1. There was excellent linearity within the range from 0.001 to 2.00 μg mL^?1, and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.     

Thermal and conductometric studies of the CeBr3–MBr binary systems (M = Li, Na)

DSC was used to investigate phase equilibrium in the CeBr₃–MBr (M = Li, Na) systems. They represent typical examples of simple eutectic systems. The eutectic composition and eutectic temperature, x(CeBr₃) = 0.249, T_eut = 709 K and x(CeBr₃) = 0.372, T_eut = 692 K, were found for CeBr₃–LiBr and CeBr₃–NaBr systems, respectively.

The electrical conductivity of CeBr₃–MBr liquid mixtures, together with that of pure components was measured down to temperatures below solidification. Results obtained are discussed in term of possible complex formation.     

Novel hybrid polyurethane/POSS materials via bulk polymerization

Novel polyurethane (PU)/polyhedral oligomeric silsesquioxane (POSS) hybrid elastomers were synthesised via reaction carried out in bulk. The isocyanate octasubstituted POSS (NCOPOSS) was used as the crosslinking agent for the polyurethane systems, which were similar to those commercially available for the production of urethane elastic materials (in contrast to model systems previously reported in literature). The structure and amorphous morphology of the resulting elastomers were confirmed by FTIR ATR spectroscopy and WAXS measurements, respectively. The elastomers were characterized by their mechanical (tensile, hardness) and thermal (T_g, thermal stability) properties. It was found that the incorporation of small amount (1.2–2.5 wt.%) of the NCOPOSS into the formulation resulted in an improvement or deterioration in mechanical properties of the polymer, depending on the diisocyanate used. Further increase in the NCOPOSS concentration resulted only in a loss of mechanical properties. A possible explanation is an over-crosslinking or wastage of POSS-deriving NCO groups (which did not react earlier with bulky polyols) in the reaction with the chain extender leading to cycle formation. Incorporation of the NCOPOSS into the PU elastomer reduced somewhat thermal stability of the latter probably due to the poor thermal stability of the NCOPOSS itself.     

The effect of linker of electrodes prepared from sol–gel ionic liquid precursor and carbon nanoparticles on dioxygen electroreduction bioelectrocatalysis

The effect of linker of three-dimensional, hydrophilic-carbon-nanoparticle film-electrodes prepared by layer-by-layer method on redox probe accumulation and bioelectrocatalytic dioxygen reduction was studied and compared for two different electrode scaffolds. The linker in both of these scaffolds was based on the same ionic liquid sol–gel precursor, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium bis(trifluoromethyl-sulfonyl)imide. The first electrode type was prepared by alternative immersion of tin doped indium oxide substrate in an aqueous suspension of carbon nanoparticles modified with phenyl sulphonic groups and a sol composed of ionic liquid sol–gel precursor and tetramethoxysilane. For the second electrode type sol was replaced by a methanolic suspension of silicate submicroparticles with appended imidazolium functional groups. In both films 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) anions accumulate irreversibly. In the case of the first electrode electrostatic attraction plays the more important role in comparison to the case of the second where stable adsorption of the redox probe takes place. After adsorption of bilirubin oxidase, electrodes obtained from sol and carbon nanoparticles exhibit modest bioelectrocatalytic activity towards dioxygen reduction at pH 4.8, however those obtained from oppositely charged particles are much more efficient. The magnitude of the associated catalytic current in both cases depends on the number of immersion and withdrawal steps. Interestingly, mediatorless catalysis at electrodes obtained from oppositely charged particles is more efficient than mediated catalysis.     

Determination of the adulteration of butter

The adulteration of butter is a serious problem due to economic advantages taken by replacing expensive milk fat with cheaper oil without informing the customers. The authentication of milk fat methods include analysis of bulk components, especially triacylglycerols, fatty acids, sterols and tocopherols. Fatty acid and sterol composition was analysed by using GC‐MS. TAG and tocopherol profiles were examined by HPLC with diode array (DAD) and fluorescence detectors (FLDs). In addition, identification of selected TAG of butter fat was conducted by LC‐atmospheric pressure chemical ionisation (APCI)/MS technique. The lipid composition of 16 different butters available on Polish market were investigated. The cholesterol content in butter fat ranged from 176.8 to 264.8 mg/100 g of fat and in two samples of milk fat β‐sitosterol was found. The total saturated fatty acid (SFA) content in milk fat was 67.1–73.5%, monounsaturated fatty acid 24.5–30.5% and polyunsaturated fatty acid was 1.2–2.0%. Abnormalities in fatty acid profiles, e.g. high concentration of linoleic fatty acid, were found in two butters. These abnormalities were also determined in TAG profiles. The examination of tocopherols in butter fat confirmed that two products were adulterated by the addition of plant oils because they contained δ‐tocopherol which is typical for plant origin foodstuffs. The methods described are useful for investigating milk fat adulterations, and the most efficient are analysis of sterols and tocopherols composition. Practical applications: The described methods are useful for investigating adulteration of milk fat. Traditional strategies rely on examination of fatty acids methyl esters and TAG; these methods have some disadvantages. Due to the variability of fatty acid composition of milk fat and because TAG analysis is complex and time consuming, FA analysis is not an efficient approach for butter authentication. The most efficient method for butter authentication is qualitative and quantitative analysis of sterols and tocopherols. This analysis will determine if components of plant origin were used for butter production.