Fitting Single Particle Energies in sdgh Major Shell

We have performed two kinds of non-linear fitting procedures to the single-particle energies in the sdgh major shell to obtain better shell model results. The low-lying energy eigenvalues of the light Sn isotopes with A = 103- 110 in the sdgh-shell are calculated in the framework of the nuclear shell model by using CD-Bonn two-body effective nucleonnucleon interaction. The obtained energy eigenvalues are fitted to the corresponding experimental values by using two different non-linear fitting procedures, i.e., downhill simplex method and clonal selection method. The unknown single-particle energies of the states 2s1/2, 1d3/2, and 0h11/2are used in the fitting methods to obtain better spectra of the104,106,108,110 Sn isotopes. We compare the energy spectra of the104,106,108,110 Sn and103,105,107,109 Sn isotopes with/without a nonlinear fit to the experimental results.     

First Electroanalytical Methodology for the Determination of Hordenine in Dietary Supplements using a Boron‐doped Diamond Electrode

The present work describes the first electrochemical investigation and a simple, rapid and modification‐free electroanalytical methodology for quantification of hordenine (a potent phenylethylamine alkaloid) using a boron‐doped diamond electrode. At optimized square‐wave voltammetric parameters, the observed oxidation peak current in 0.1 M HClO₄ at +1.33 V (vs. Ag/AgCl) increased linearly from 5.0 to 100 μg mL^?1 (3.0×10^?5–6.1×10^?4 M), with detection limit of 1.3 μg mL^?1 (7.8×10^?6 M). The applicability of the developed method was tested with the determination of hordenine in the commercial dietary supplement formulations.     

LC-DAD-ESI-MS/MS-based phenolic profiling of St John’s Wort Teas and their antioxidant activity: Eliciting infusion induced changes

Infusion-induced changes in the phenolics, antioxidant and colour propeties of St John’s wort (genus, Hypericum; specie, Hypericum perforatum L.) teas were studied for the first time. SJW teas prepared as three different infusions and coded as three (3?min), six (6?min) and twelve minutes (12?min). Investigation of phenolic compounds were performed by LC-DAD-ESI-MS/MS. A total of 18 phenolics including six chlorogenic acids, three phenolic acids, seven flavonoids and two naphtodianthrones were detected. It is worth noting that the phenolic profiles of St John’s wort teas were similar. However, the quantities of phenolic compounds individually and totally changed significantly for different infusion times. The highest total concentration was detected in 12?min (60.03?mg/L), followed by 6?min (54.81?mg/L) and 3?min (33.07?mg/L). The main difference for different infusion times was the hyperoside found as the most abundant phenolic only in 3?min samples. However, for 6?min and 12?minin infusions, chlorogenic acid was the most dominant phenolic compound. Similar to phenolics, antioxidant capacity of tea infusions showed an increasing trend with the extension of infusion time.     

Coumarin Based Highly Selective “off-on-off” Type Novel Fluorescent Sensor for Cu<Superscript>2+</Superscript> and S<Superscript>2−</Superscript> in Aqueous Solution

Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, ¹H, ¹³C, ¹³C–APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed “on–off” type fluorescence response towards Cu²⁺ with high selectivity in aqueous solution (CH₃CN/H₂O, 9/1, v/v). Once binding with Cu²⁺, CFHC-Cu²⁺ complex also displayed high selectivity for sulfide, resulting in “off–on” type sensing of sulfide anion.

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Graphical abstract Visual fluorescence changes upon addition of various metal ions (5.0 eq.) to CFHC in CH₃CN/H₂O (90:10, v/v) under UV excitation (365 nm)

     

Computation of thermal fracture parameters for orthotropic functionally graded materials using Jk-integral

This article introduces a computational method based on the J_k-integral for mixed-mode fracture analysis of orthotropic functionally graded materials (FGMs) that are subjected to thermal stresses. The generalized definition of the J_k-integral is recast into a domain independent form composed of line and area integrals by utilizing the constitutive relations of plane orthotropic thermoelasticity. Implementation of the domain independent J_k-integral is realized through a numerical procedure developed by means of the finite element method. The outlined computational approach enables the evaluation of the modes I and II stress intensity factors, the energy release rate, and the T-stress. The developed technique is validated numerically by considering two different problems, the first of which is the problem of an embedded crack in an orthotropic FGM layer subjected to steady-state thermal stresses; and the second one is that of periodic cracks under transient thermal loading. Comparisons of the mixed-mode stress intensity factors evaluated by the J_k-integral based method to those calculated through the displacement correlation technique (DCT) and to those available in the literature point out that, the proposed form of the J_k-integral possesses the required domain independence and leads to numerical results of high accuracy. Further results are presented to illustrate the influences of the geometric and material constants on the thermal fracture parameters.     

Linear stability analysis in compressible, flat-plate boundary-layers

The stability problem of two-dimensional compressible flat-plate boundary layers is handled using the linear stability theory. The stability equations obtained from three-dimensional compressible Navier–Stokes equations are solved simultaneously with two-dimensional mean flow equations, using an efficient shoot-search technique for adiabatic wall condition. In the analysis, a wide range of Mach numbers extending well into the hypersonic range are considered for the mean flow, whereas both two- and three-dimensional disturbances are taken into account for the perturbation flow. All fluid properties, including the Prandtl number, are taken as temperature-dependent. The results of the analysis ascertain the presence of the second mode of instability (Mack mode), in addition to the first mode related to the Tollmien–Schlichting mode present in incompressible flows. The effect of reference temperature on stability characteristics is also studied. The results of the analysis reveal that the stability characteristics remain almost unchanged for the most unstable wave direction for Mach numbers above 4.0. The obtained results are compared with existing numerical and experimental data in the literature, yielding encouraging agreement both qualitatively and quantitatively.      

Analysis of Biogenic Amines Using Immunoassays,HPLC, and a Newly Developed IC-MS/MS Technique in Fish Products—A Comparative Study

In this study, comparative analyses were carried out with ion chromatography mass-spectrometry (IC-MS/MS) which has no derivatization step, high-performance liquid chromatography (HPLC) technique, as well as two quantitative and two semi-quantitative immunoassays. The results demonstrated that HPLC and quantitative immunoassay methods were well-correlated with IC-MS/MS in determining histamine in various types of fish products. The best correlation was observed with the HistaSure ELISA Fast Track kit (R² = 0.9903). More than half of the values (68%) obtained by two methods were also statistically similar. The results of semi-quantitative test kits also supported histamine values estimated by quantitative methods, with some exceptions. The best results were found for HistaSure Lateral Flow in supporting the quantitative techniques. Therefore, these methods are found suitable for monitoring histamine in fish products in terms of food safety. Good correlations were also observed HPLC and IC-MS/MS in determining cadaverine, putrescine, and tyramine with the highest value observed for tyramine as R² = 0.9785. However, no correlation was observed for other biogenic amines, and the majority of the results were significantly different from each other for these amines (p < 0.05). The differences may be caused by the drawbacks reported previously for HPLC. However, further studies are required to confirm the possible effects. This study provides a comparative evaluation of several methods in terms of their suitability in determining biogenic amines in fish products for both monitoring and regulatory purposes.     

Anticholinesterase activity screening of some novel dithiocarbamate derivatives including piperidine and piperazine moieties

The present study was undertaken to synthesize some novel lipophilic piperazine and piperidinedithiocarbamates and investigate their inhibitory potencies against cholinesterase enzymes. In the synthetic studies, 44 new compounds were isolated. The structures of the synthesized compounds were confirmed by spectroscopic analyses. Enzymatic studies were carried out using modified Ellman's assay against Acetylcholinesterase (AChE) and Butrylcholinesterase (BChE) enzymes, and it was observed that some of the compounds selectively inhibit AChE. Theoretical ADME predictions were calculated for selected compounds in the series. Enzyme kinetics and molecular docking studies were performed for the most active compound C41 and nature of inhibition and interactions between enzyme and ligand were explained.