Effects of Salinity and Ultraviolet Radiation on the Bioaccumulation of Mycosporine‐like Amino Acids in Artemia from Lake Urmia (Iran)

We investigated the effects of salinity and artificial UV radiation on the accumulation of mycosporine‐like amino acids (MAAs) in sexual and parthenogenetic Artemia from Lake Urmia. The nauplii hatched from the cysts were cultured until adulthood under two salinities (150 and 250 g L^?1) and two light treatments (PAR and PAR+UVR) in the laboratory. Finally, the Artemia were analyzed for their concentration of MAAs. In most of the cases, the higher salinity level applied was found to increase the MAA concentrations in both Artemia populations significantly. The acquisition efficiency of MAAs in both Artemia populations increased under exposure to UVR‐supplemented photosynthetically active radiation (PAR) compared to those raised under PAR, except for Porphyra‐334. It was observed that combination of UV radiation and elevated salinity significantly increased the bioaccumulation of MAAs. Thus, the presence of these compounds in these populations of Artemia may increase their adaptability for living in high‐UV and high‐salinity conditions prevailing in Lake Urmia. Higher concentrations of MAAs in the parthenogenetic population of Artemia could be probably attributed to its mono sex nature and higher adaptation capacities to extreme environmental conditions.     

Domino Michael–<Emphasis Type="Italic">O</Emphasis>-alkylation: one-pot synthesis of dialkyl 4-oxo-2,3-dihydro-2,3-furandicarboxylates

Abstract  

The KSCN-catalyzed reaction of dialkyl acetylenedicarboxylates with pentane-2,4-dione in acetone, led to dialkyl 2-(1-acetyl-2-oxopropyl)-2-butenedioates in excellent yields. When these reactions were carried out in MEK (butane-2-one), dialkyl 4-oxo-2,3-dihydro-2,3-furandicarboxylates were obtained exclusively. This difference in reactivity is discussed in terms of the possibility of cationic exchange in butane-2-one.     

Hydrogen abstraction reactions of hydroxyl radicals with 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane and pentachloroethane studied by using semi-classical transition state theory

The hydrogen abstraction reactions by OH radicals from CHCl₂CHCl₂ (R1), CH₂ClCCl₃ (R2) and C₂HCl₅ (R3) are investigated theoretically by semi-classical transition state theory. Many high-level density functional, ab initio and combinatory electronic structure calculation methods are used to evaluate the energies and ro-vibrational properties of the stationary points for the title reactions. x_ij vibrational anharmonicity coefficients, needed for semi-classical transition state theory, are calculated at the KMLYP/cc-pVTZ level of theory. Thermal rate coefficients are computed over the temperature range from 200 to 2000 K and compared with available experimental data. The computed rate constants for the reactions R1, R2 and R3 are fitted to the equation k(T) = ATⁿexp?[ ? E(T + T₀)/(T² + T²₀)].     

Speciation of chromium in water samples using dispersive liquid–liquid microextraction and flame atomic absorption spectrometry

A novel method for preconcentration is described for chromium speciation at microgram per liter to sub-microgram per liter levels. It is based on selective complex formation of both Cr(VI) and Cr(III) followed by dispersive liquid–liquid microextraction and determination by microsample introduction-flame atomic absorption spectrometry. Effects influencing complex formation and extraction (such as pH, temperature, time, solvent, salinity and the amount of chelating agent) have been optimized. Enrichment factors up to 275 and 262 were obtained for Cr(VI) and total Cr, respectively. The calibration graph is linear from 0.3 to 20 µg L^?1, and detection limits are 0.07 and 0.08 µg L^?1 for Cr(VI) and total Cr, respectively. Relative standard deviations (RSDs) were obtained to be 2.0% for Cr(VI) and 2.6% for total Cr (n?=?7).     

Fe3O4@SiO2@ADMPT/H6P2W18O62: a novel Wells–Dawson heteropolyacid-based magnetic inorganic–organic nanohybrid material as potent Lewis acid catalyst for the efficient synthesis of 1,4-dihydopyridines

A novel Wells–Dawson heteropolyacid-based magnetic Inorganic–organic nanohybrid, Fe₃O₄@SiO₂@ADMPT/H₆P₂W₁₈O₆₂, was fabricated and used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 1,4-Dihydopyridine (1,4-DHP) derivatives from the reaction of various aromatic aldehydes with ethyl acetoacetate and ammonium acetate with good to excellent yields and in a short span of time. The nanohybrid catalyst was prepared by the chemical anchoring of Wells–Dawson heteropolyacid H₆P₂W₁₈O₆₂ onto the surface of functionalized Fe₃O₄ nanoparticles with 2,4-bis(3,5-dimethylpyrazol)-triazine (ADMPT) linker. These nanocatalysts were identified by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM). This protocol is developed as a safe, cost-effective and convenient alternate method for the synthesis of 1,4-DHP derivatives utilizing an eco-friendly, and a highly reusable catalyst.     

Mechanochemical Synthesis of High Crystalline Cerium Hexaboride Nanoparticles from CeO2‐B2O3‐Mg Ternary System

High crystalline cerium hexaboride (CeB₆) nanoparticles (NPs) were synthesized using mixture of mag‐ nesium (Mg), cerium oxide (CeO₂) and boron oxide (B₂O₃) via the mechanochemical process at room tem‐ perature. Based on the results, magnesiothermic reduction of B₂O₃ occurred after about 2 h of milling in a mechanically induced self‐sustaining reaction (MSR). The significant amount of heat produced by the reduction reaction resulted in CeO₂ reduction to elemental Ce which finally reacted with elemental B and formed CeB₆ compound. According to XRD analyses, the degree of crystallinity and lattice parameter of the product was calculated about 93 % and 4.1458 Å, respectively. The morphology observations revealed that the synthesized CeB₆ had semi‐cubic shape with the range of size 25–60 nm. The synthesis of CeB₆ during the thermal treatment was studied by simultaneous thermal analysis (STA) technique. It was found that the reduction of B₂O₃ took place after melting of Mg meanwhile, no CeB₆ phase achieved even up to 1100 °C.     

Induction and suppression of cell lysis in an electrokinetic microfluidic system

The ability to strategically induce or suppress cell lysis is critical for many cellular-level diagnostic and therapeutic applications conducted within electrokinetic microfluidic platforms. The chemical and structural integrity of sub-cellular components is important when inducing cell lysis. However, metal electrodes and electrolytes participate in undesirable electrochemical reactions that alter solution composition and potentially damage protein, RNA, and DNA integrity within device microenvironments. For many biomedical applications, cell viability must be maintained even when device-imposed cell-stressing stimuli (e.g., electrochemical reaction byproducts) are present. In this work, we explored a novel and tunable method to accurately induce or suppress device-imposed artifacts on human red blood cell (RBC) lysis in non-uniform AC electric fields. For precise tunability, a dielectric hafnium oxide (HfO₂) layer was used to prevent electron transfer between the electrodes and the electric double layer and thus reduce harmful electrochemical reactions. Additionally, a low concentration of Triton X-100 surfactant was explored as a tool to stabilize cell membrane integrity. The extent of hemolysis was studied as a function of time, electrode configuration (T-shaped and star-shaped), cell position, applied non-uniform AC electric field, with uncoated and HfO₂ coated electrodes (50 nm), and absence and presence of Triton X-100 (70 µM). Tangible outcomes include a parametric analysis relying upon literature and this work to design, tune, and operate electrokinetic microdevices to intentionally induce or suppress cellular lysis without altering intracellular components. Implications are that devices can be engineered to leverage or minimize device-imposed biological artefacts extending the versatility and utility of electrokinetic diagnostics.     

A Novel Electrochemical Sensor Based on FeNi3/CuS/ BiOCl Modified Carbon Paste Electrode for Determination of Bisphenol A

In this study, we used voltammetric method in order to examine the electrochemical behavior of BPA. Hence, we constructed a new electrochemical sensor to detect BPA on the basis of the modified carbon paste electrode using FeNi₃/CuS/BiOCl as a novel nanocomposite. Results showed that when using optimized conditions, the new BPA sensor has a wide linear range between 0.1 μM and 300 μM, lower limit of detection of 0.05 μM, and good reproducibility and stability. Based on the findings, it could be concluded that our sensor can be substantially utilized for detecting BPA in the food samples with reasonable outputs.