New Effects in Cyclophosphorylation of Polyatomic Phenols by Phosphorous Acid Amides

Electronic effects in the design of new types of phosphocontaining cavity systems were considered. The matter of this phenomenon consists in supramolecular interaction of the organic radicals of substrates with the cyclophosphorylating reagents.     

Optimization of a GC‐MS/MS Method for the Analysis of PCDDs and PCDFs in Human and Fish Tissue

This paper outlines the possibilities of selectivity and sensitivity enhancement in measuring PCDD/F congeners using an ion trap GC‐MS/MS. The pressure of the collision gas and the collision energy were optimized. The modified GC‐MS/MS method was applied to the determination of PCDDs and PCDFs in human and fish tissues. Limits of quantification were about 1 pg/g of fat for all seventeen 2378 PCDD/Fs tested (starting amount of fat, 2 g).     

Stabilization for a Fourth Order Nonlinear Schrödinger Equation in Domains with Moving Boundaries

In the present paper we study the well-posedness using the Galerkin method and the stabilization considering multiplier techniques for a fourth-order nonlinear Schrödinger equation in domains with moving boundaries. We consider two situations for the stabilization: the conservative case and the dissipative case.     

Reproducibility Evaluation of Urinary Peptide Detection Using CE-MS

In recent years, capillary electrophoresis coupled to mass spectrometry (CE-MS) has been increasingly applied in clinical research especially in the context of chronic and age-associated diseases, such as chronic kidney disease, heart failure and cancer. Biomarkers identified using this technique are already used for diagnosis, prognosis and monitoring of these complex diseases, as well as patient stratification in clinical trials. CE-MS allows for a comprehensive assessment of small molecular weight proteins and peptides (<20 kDa) through the combination of the high resolution and reproducibility of CE and the distinct sensitivity of MS, in a high-throughput system. In this study we assessed CE-MS analytical performance with regards to its inter- and intra-day reproducibility, variability and efficiency in peptide detection, along with a characterization of the urinary peptidome content. To this end, CE-MS performance was evaluated based on 72 measurements of a standard urine sample (60 for inter- and 12 for intra-day assessment) analyzed during the second quarter of 2021. Analysis was performed per run, per peptide, as well as at the level of biomarker panels. The obtained datasets showed high correlation between the different runs, low variation of the ten highest average individual log2 signal intensities (coefficient of variation, CV < 10%) and very low variation of biomarker panels applied (CV close to 1%). The findings of the study support the analytical performance of CE-MS, underlining its value for clinical application.     

Chemical Modifications on Polystyrene Latex: Preparation and Characterization for Use in Immunological Applications

Polystyrene latex microspheres are efficient supports for immunological reactions. In the presence of suitable functional groups these microspheres may react by covalent binding with antigens or antibodies and have been extensively used in immunoassay technique. By using the emulsion polymerization and diazotization methods, a kind of functionalized latex was prepared. The preparation of this latex consisted of six syntheses of polystyrene followed by nitration, amination and diazotization. A narrow distribution of particle size was obtained in all the cases. The synthesis that presented 98% of monomer conversion and the largest particle size diameter 0.2 ± 0.05 μm was chosen for the subsequent chemical treatments. The chemical characterizations of every step were performed by Fourier transform infrared and Raman spectroscopies. The particle size was determined by a submicrometer particle analyzer and scanning electron microscopy. The polydiazostyrene latex obtained was sensitized using bovine serum albumin (BSA) and when it was submitted to agglutination assay in the presence of a rabbit serum containing specific antibodies to BSA demonstrated efficient results. © 1997 John Wiley & Sons, Ltd.     

Urease‐Catalyzed Carbonate Precipitation inside the Restricted Volume of Polyelectrolyte Capsules

A new biomimetic approach for performing CaCO₃ synthesis exclusively inside micron‐sized polyelectrolyte capsules, based on the fermentative formation of a precipitative agent (CO₃²⁻ anion) by urease‐catalyzed urea hydrolysis, was developed. Precipitated CaCO₃ completely fills the interior capsule volume and has a metastable vaterite phase.

     

Separation and Analysis of Theran Volcanic Glass by INAA, XRF and EPMA

 Pumice from the “Minoan eruption” on Thera (Cyclades, Greece) was investigated to reveal the differences between the composition of the bulk material, which contains a certain percentage of crystallites, and the pure glass phase. This is important for the identification of vitric tephra layers found in the Eastern Mediterranean region in archaeological context and in deep sea drilling cores. Eruption products, deposited at some distance, have usually lost their crystalline fraction due to gravity separation and consist only of glass shards. Only major element distributions in such layers and in pumiceous glass phases have been published up to now, but these data are not sufficient for a reliable identification of the volcanic source, as several other eruptions are known to have produced chemically very similar layers in this region (Milos, Nisyros, Yali, Kos). Therefore, a technique has been developed to separate the glass phase from the primary pumice to reveal differences in the trace element distributions obtained by instrumental neutron activation analysis (INAA). X-ray diffractometry and microscopical techniques were applied to check the purity of this fraction. The concentrations of the major constituents, in particular Al, Ca, Fe, K, Mg, Mn, Na, Si, and Ti were determined by X-ray fluorescence (XRF) and electron probe microanalysis (EPMA), those of Al, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Ti, Th, U, Yb and Zr by instrumental neutron activation analysis and partly also by X-ray fluorescence. Subtle differences between the compositions of the glass phase and the bulk material are explained by differentiation during partial crystallization and their applicability to the classification of tephra layers is demonstrated.     

Separation and determination of Ni(II), Co(II) and Cu(II) by RP-HPLC with hexadecyltrimethylammonium bromide/n-propanol mobile phases

Summary The effect of the presence of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), and a short chain alcohol,n-propanol, in the mobile phase on the chromatographic retention of Co(II), Ni(II) and Cu(II) diethylammonium diethyldithiocarbamate complexes, has been studied. A simple isocratic reversephase method for the determination of the metals is proposed, using a mobile phase of composition CTAB 0.03 M/n-propanol 45 %v/v. Detection limits at pg levels were obtained for all solutes. The method was applied to the determination of the complexes in tap water samples at three different concentrations, with recoveries close to 100%. In order to evaluate the interaction between the metal complexes and the aggregates formed, the values of solute binding constants are calculated.