SPE and determination by FAAS of heavy metals using a new synthesized polymer resin in various water and dried vegetables samples

Firstly, poly[phenyl thiadiazole methacrylamide-co-divinylbenzene-co-2-acrylamido-2-methylpropane sulfonic acid] (PTMAAm-co-DVB-co-AMPS), a new polymer resin was synthesized. This polymer resin was characterized by elemental analyzer, X-ray diffractometer, scanning electron microscope (SEM) and IR spectrometer. The glass column packed with the synthesized polymer resin was used for solid phase extraction (SPE). At the same time, the analytes were separated and preconcentrated from various water, dried vegetables samples and standard reference material (CRM) with SPE and determined by flame atomic absorption spectrometer (FAAS). The experimental conditions of this method such as pH, flow rates of sample, flow rates of eluent, type / concentration / volume of eluent, sample volume and matrix ions were examined. The limits of detection (µg L^?1) were calculated (3s) 0.9 for Mn(II), 1.4 for Cd(II), Co(II) and Zn(II), 1.5 for Cr(III), 2.2. for Cu(II), 1.9 for Pb(II),1.5 for Ni(II) and 1.9 for Fe(III) (n = 21). The low relative standard deviation, ≤ 2% (n = 11) and preconcentration factor as 75 for analytes were obtained.     

New chiral ruthenium(II)–phosphinite complexes containing a ferrocenyl group in enantioselective transfer hydrogenations of aromatic ketones

A new and versatile class of unsymmetrical ferrocenyl-phosphinite ligands possessing a stereogenic center has been prepared from commercially available, inexpensive aminoacids such as, d-, l-phenylglycine and d-, l-phenylalanine, through a concise synthetic procedure. These ligands are not very sensitive to air and moisture, and display good enantioselectivities in the ruthenium-catalyzed asymmetric transfer hydrogenation of acetophenone derivatives, in which up to 91% ee was obtained. A comparison of the catalytic properties of amino alcohols and other analogues based on a ferrocenyl backbone is also discussed briefly. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy, and elemental analysis.     

One Spot Microwave Synthesis and Characterization of Nitrogen-Doped Carbon Dots with High Oxygen Content for Fluorometric Determination of Banned Sudan II Dye in Spice Samples

Journal of Fluorescence - A simple microwave-assisted synthesis of nitrogen-doped carbon dots with high oxygen content (O-N-CDs) was carried out with citric acid as a carbon source and...     

Re-Evaluation of a Fulvene-Based Self-Replicating Diels–Alder Reaction System

We re-evaluate our claim of a high diastereoselectivity in the self-relicating Diels–Alder reaction between maleimide 1 and fulvene 3 . It was shown that the system has a diastereoselectivity of 1.8:1 for NN-4 : NX-4 , which is contrary to the 16:1 ratio claimed by Dieckmann et al. The analysis of ¹H NMR monitoring of the reaction revealed that both replicators show sigmoidal growth which is typical for auto-catalytic systems.     

Restricted Modules and Conjectures for Modules of Constant Jordan Type

We introduce the class of restricted k[A]-modules and p ^t -Jordan types for a finite abelian p-group A of exponent at least p ^t and a field k of characteristic p. For these modules, we generalize several theorems by Benson, verify a generalization of conjectures stated by Suslin and Rickard giving constraints on Jordan types for modules of constant Jordan type when t is 1. We state conjectures giving constraints on p ^t -Jordan types and show that many p ^t -Jordan types are realizable.     

Intermediate behavior of Kerr tails

The numerical investigation of wave propagation in the asymptotic domain of Kerr spacetime has only recently been possible thanks to the construction of suitable hyperboloidal coordinates. The asymptotics revealed an apparent puzzle in the decay rates of scalar fields: the late-time rates seemed to depend on whether finite distance observers are in the strong field domain or far away from the rotating black hole, an apparent phenomenon dubbed ‘splitting.’ We discuss far-field ‘splitting’ in the full field and near-horizon ‘splitting’ in certain projected modes using horizon-penetrating, hyperboloidal coordinates. For either case we propose an explanation to the cause of the ‘splitting’ behavior, and we determine uniquely decay rates that previous studies found to be ambiguous or immeasurable. The far-field ‘splitting’ is explained by competition between projected modes. The near-horizon ‘splitting’ is due to excitation of lower multipole modes that back excite the multipole mode for which ‘splitting’ is observed. In both cases ‘splitting’ is an intermediate effect, such that asymptotically in time strong field rates are valid at all finite distances. At any finite time, however, there are three domains with different decay rates whose boundaries move outwards during evolution. We then propose a formula for the decay rate of tails that takes into account the inter-mode excitation effect that we study.     

A DFT Study on Estrone – TNT Interaction

Trinitrotoluene, known as TNT, is a widely used powerful explosive. It is a poisonous material, which injures almost all cells, especially those of liver, bone marrow, and kidney. Estrone is a sex hormone having an electron rich aromatic (phenolic) ring that is capable of forming a π complex with molecules containing an electron deficient π system. This study has focused on investigating the tendency of the complex formation of TNT with estrone. It has been thought that the formation of estrone‐TNT π complex might take place in a human body exposed to acute or prolong period of this hazardous chemical and consequently estrone activities might be impaired. The complex formation reaction was investigated mainly using DFT method with B3LYP/6‐31G(d, p) basis set in gas phase. The existence of π interaction between estrone and TNT was demonstrated by computational spectroscopic analyses (UV/Vis, IR, and ¹H NMR techniques). The frontier molecular orbital (HOMO and LUMO) analyses have shown that the considered π complex is very resistant to oxidation with respect to its components, estrone and TNT.     

Statistical Extensions of Some Classical Tauberian Theorems for Cesàro Summability of Triple Sequences

Some growth conditions of the resolvent function of a Banach space operator are investigated using higher order Cesàro means. More precisely, Abel and Nevanlinna estimates are obtained under the condition of boundedness of some weighted Cesàro averages. Also, certains results related to the (strong or uniform) convergence of Cesàro means are mentioned.