Monitoring and Exposure Assessment of Fosetyl Aluminium and Other Highly Polar Pesticide Residues in Sweet Cherry

Cherries are popular fruits due to their health benefits, organoleptic quality, and attractive appearance. Since highly polar pesticides are of low mass and amphoteric character, and are not amenable to traditional multi-residue extraction methods, they are more commonly not included in the pesticide monitoring program. This study aims to determine twelve highly polar pesticide residues in cherry samples intended for export from Turkey. A total of 16,022 cherry samples from 2018–2020 harvests in four production areas of Turkey were analyzed using a modification of the Quick Polar Pesticides method and liquid chromatography-tandem mass spectrometry. The method was validated at two fortification levels (0.01 and 0.05 mg kg⁻¹), and good recoveries (87.4–111.4%) and relative standard deviations (<6%) were achieved for all analytes. The limits of quantification were in the range of 1.08–2.55 μg kg⁻¹. Overall, 28.4% of the analyzed cherry samples were detected with phosphonic acid, calculated as fosetyl aluminium (fosetyl-Al) in amounts up to 77.7 mg kg⁻¹. For 2304 samples (14.4%), the residues exceeded the European Union maximum residue level of 2 mg kg⁻¹. There is no reason to be concerned about long-term exposure to phosphonic acid/fosetyl-Al, and the other highly polar pesticides through the consumption of sweet cherry.     

A software tool to evaluate the frequency response of a microwave photonic filter in MATLAB based on a Graphical User Interface

The aim of this paper is to describe the development and application of a software tool in MATLAB based on a Graphical User Interface that allows evaluation of the frequency response of a microwave photonic filter. Microwave photonic filters have potential applications in optical communication systems. The main characteristic of this software tool is the friendly way to edit the parameters involved to determine the frequency response. In order to validate the results obtained by the use of this software tool, a series of experiments were carried out in our laboratory and the results were compared qualitatively showing a good agreement. The developed software has a potential application as a didactic tool in a course of microwave electro-optical systems.     

MHD flow and heat transfer in a thin liquid film on an unsteady stretching sheet by the homotopy analysis method

The magnetohydrodynamics flow and heat transfer in a thin liquid film over an unsteady elastic stretching surface are analyzed by the homotopy analysis method. A more general surface temperature is taken into consideration. The effects of various parameters in this study are discussed and presented graphically. The good agreement between the analytic series solutions and the previous numerical results shows the effectiveness of HAM to this problem. Copyright © 2009 John Wiley & Sons, Ltd.     

Validation of an analytical method to determine sulfamides in kidney by HPLC-DAD and PARAFAC2 with first-order derivative chromatograms

Six sulfamides were extracted from kidney and analysed by high-performance liquid chromatography with diode array detection (HPLC-DAD): sulfadiazine, sulfamethazine, sulfamethoxypyridazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline.Two main difficulties arose in identifying and quantifying the analytes. Firstly, the chromatographic peaks of the matrix interferences overlapped with those of the analytes. The uniqueness property of PARAFAC2 solved this problem. Secondly, the gradient elution caused a baseline drift. The first-order derivative of the chromatograms minimized its effect.The analytical method was validated. As the performance criteria detailed in the European Decision 2002/657/EC are based on specific signals, this paper generalizes those criteria for higher-order and non-specific signals. In this sense the proposed methodology is general and can be applied to any chromatographic method (HPLC or GC) with a detector that provide a multivariate signal (MS, DAD, EC, etc.).     

Gromov–Hausdorff stability of linkage-based hierarchical clustering methods

A hierarchical clustering method is stable if small perturbations on the data set produce small perturbations in the result. These perturbations are measured using the Gromov–Hausdorff metric. We study the problem of stability on linkage-based hierarchical clustering methods. We obtain that, under some basic conditions, standard linkage-based methods are semi-stable. We also prove that, avoiding exotic examples, introducing any unchaining condition in the algorithm always produces unstable methods.     

Building robust calibration models for the analysis of estrogens by gas chromatography with mass spectrometry detection

Five hormonal growth promotants (diethylstilbestrol, hexestrol, dienestrol, 17-β-estradiol and 17-α-ethynylestradiol) have been analysed by gas chromatography with mass spectrometry detection (GC/MS, SIM mode) for four non-consecutive days. The aim is to build models with stable predictions. The strategies applied are internal standardization and global models carried out by gathering signals recorded on several days. Two models were examined: univariate models (with standardized peak area) and PARAFAC2 (the analyte scores were standardized by the scores of the internal standard). Internal standardization has been proved to be efficient for both models of dienestrol and ethynylestradiol. The mean relative error in absolute value when samples recorded on a different day to the calibration set are quantified by PARAFAC2 is 7.00% and 7.11% for dienestrol and ethynylestradiol, respectively. For diethylstilbestrol and estradiol, internal standardization was combined with global calibration models built with signals recorded under several sources of variability (different days). Thus predictions become steadier over time and in the estradiol example, errors decrease from 33.10% to 9.76%. The mean relative error in absolute value with PARAFAC2 updated models oscillates between 6.34% for ethynylestradiol and 10.74% for diethylstilbestrol. For univariate updated models errors range from 6.42% to 14.19% for ethynylestradiol and estradiol respectively. The combination of both strategies has been proved to be efficient independently of the analyte and of the signal order.     

Bias-induced changes in carrier type of Pb(1−x)Fe(x)S nanocrystalline solution grown thin films

Change of majority carrier type was achieved in nanocrystalline Pb_(1−x)Fe_(x)S thin films by applying a DC-bias on the substrate during their growth by solution growth technique. Critical control of biasing and pH of the solution bath are observed to be necessary to achieve this change. The DC-bias results in slight change in relative concentrations of the constituents in the films, which lead to change in majority carriers without any measurable change in lattice parameter. This modification to the conventional solution growth technique provides the possibility to grow abrupt homojunctions in the nanocrystalline films by sudden change in DC-biasing during film growth.     

Synthesis,anticancer, molecular docking and QSAR studies of benzoylhydrazone

To find out effective anticancer compounds we synthesized (1–30) derivatives of 4-isopropylbenzoylhydrazone and evaluated for anticancer potential. The compounds 3, 9, 12, 23, 26 and 28 showed better activities ranging (0.39–1.1 µg/ml) than the standard (1.53 ± 0.01 µg/ml). In line with this, compounds 2, 6, 24, 25 and 29 exhibited better activities compared to the second standard (5FU 4.60 ± 0.01 µg/ml). The best molecular docked complex between the BRCA1 structure and the 1–30 derivatives were analyzed based on the Glide docked score and binding orientation for both the SP and XP mode. The 2D-QSAR analysis reflected a significant correlation between the experimental and the predicted biological activities. The above-mentioned compounds were also assessed by various spectroscopic techniques.     

Extension of Fermat’s last theorem in Minkowski natural spaces

Journal of Mathematical Chemistry - Minkowski natural (N?+?1)-dimensional spaces constitute the framework where the extension of Fermat’s last theorem is discussed. Based on...