Determination of the leaching rate of radionuclide 134Cs from the solidified radioactive wastes in Syrian Portland cement and cement–microsilica matrixes

The suitability of Syrian Portland cement for disposal of solidified low-level radioactive waste was assessed by measuring the leaching rate of ¹³⁴Cs. In ordinary cement concrete, a leaching rate of 1.309 × 10^?3 g/cm² per day was measured. Mixing this concrete with microsilica reduced significantly the leaching rate to 3.106 × 10^?4 g/cm² per day for 1% mixing, and to 9.645 × 10^?5 g/cm² per day for 3% mixing. It was also found that the application of a latex paint reduced these leaching rates by about 10%. These results, along with mechanical strength tests (under radiation exposure, high temperature, long water immersion and freeze–thaw cycling) indicate that Syrian Portland cement is suited for the disposal of low-level radioactive waste.     

Sorption of stable and radioactive Cs(I), Sr(II), Co(II) ions on Ti–Ca–Mg phosphates

Journal of Radioanalytical and Nuclear Chemistry - In this paper, we studied the features of stable and radioactive Cs(I), Sr(II) and Co(II) ions sorption on Ti–Ca–Mg phosphates. The...     

Recent achievements on the agricultural applications of thioether derivatives: A 2010–2020 decade in review

Thioether derivatives, an important synthetic strategy in drug discovery, are acquiring more importance in plant protection field in recent years because of their broad spectrum of agricultural activities, such as antifungal, antibacterial, insecticidal, acaricidal, nematocidal, antiviral, herbicidal, and plant growth-regulating activity. Thioethers and their analogues have been an area of great interest in recent years. This review summarizes the structure and agricultural activities of the thioether derivatives as reported in the literature that mainly covers the past 10 years from 2010 to 2020 as well as may contribute to a better understanding of thioether derivatives as efficient agricultural agents and provide some ideas on the development of novel pesticides.     

Applications of capillary electrophoresis in the fields of environmental,pharmaceutical, clinical,and food analysis (2019–2021)

So far, the potential of capillary electrophoresis in the application fields has been increasingly excavated due to the advantages of simple operation, short analysis time, high-resolution, less sample consumption, and low cost. This review examines the implementations and advancements of capillary electrophoresis in different application fields (environmental, pharmaceutical, clinical, and food analysis) covering the literature from 2019 to 2021. In addition, ultrasmall sample injection volume (nanoliter range) and short optical path lead to relatively low concentration sensitivity of the most frequently used ultraviolet-absorption spectrophotometric detection, so the pretreatment technology being developed has been gradually utilized to overcome this problem. Despite the review being focused on the development of capillary electrophoresis in the fields of environmental, pharmaceutical, clinical, and food analysis, the new sample pretreatment techniques of microextraction and enrichment fit excellently to capillary electrophoresis in recent three years are also described briefly.     

The Development of Planar Chromatography in 1980–1990 and 2000–2010 (the Scientometric Study)

JPC – Journal of Planar Chromatography – Modern TLC - The scientometric study of the tendencies of change of basic chromatographic characteristics has been carried out based on the...     

Host-guest supramolecular interactions in the coordination compounds of 4,4'-azobis(pyridine) with MnX2 (X = NCS–, NCNCN–, and PF6(–)): structural analyses and theoretical study

Three new Mn(II) coordination compounds {[Mn(NCNCN)(2)(azpy)]·0.5azpy}(n) (1), {[Mn(NCS)(2)(azpy)(CH(3)OH)(2)]·azpy}(n) (2), and [Mn(azpy)(2)(H(2)O)(4)][Mn(azpy)(H(2)O)(5)]·4PF(6)·H(2)O·5.5azpy (3) (where azpy = 4,4'-azobis(pyridine)) have been synthesized by self-assembly of the primary ligands, dicyanamide, thiocyanate, and hexafluorophosphate, respectively, together with azpy as the secondary spacer. All three complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses, and single crystal X-ray crystallography. The structural analyses reveal that complex 1 forms a two-dimensional (2D) grid sheet motif. These sheets assemble to form a microporous framework that incorporates coordination-free azpy by host-guest π···π and C-H···N hydrogen bonding interactions. Complex 2 features azpy bridged one-dimensional (1D) chains of centrosymmetric [Mn(NCS)(2)(CH (3)OH)(2)] units which form a 2D porous sheet via a CH(3)···π supramolecular interaction. A guest azpy molecule is incorporated within the pores by strong H-bonding interactions. Complex 3 affords a 0-D motif with two monomeric Mn(II) units in the asymmetric unit. There exist π···π, anion···π, and strong hydrogen bonding interactions between the azpy, water, and the anions. Density functional theory (DFT) calculations, at the M06/6-31+G* level of theory, are used to characterize a great variety of interactions that explicitly show the importance of host-guest supramolecular interactions for the stabilization of coordination compounds and creation of the fascinating three-dimensional (3D) architecture of the title compounds.     

A novel lariat-silacrown ether based in sol–gel process: synthesis, characterization and interaction study with the copper(II) ion

The synthesis and characterization of the lariat-silacrown ether (Sila15NH??IUPAC name: 3-[1-[[1-(3-aminopropyl)-2,5,8,11,14-pentaoxa-1-silacyclotetradec-1-yl] oxy]-2,5,8,11,14-pentaoxa-1-silacyclotetradec-1-yl]propan-1-amine) and its complex with copper(II) ion, Cu(II)?CSila15NH, are reported in this work. Tetraethylene glycol, 3-aminopropyl triethoxysilane and metallic sodium were employed as precursors and the lariat-silacrown ether obtained in a good yield (64?%) was characterized by elemental analysis, infrared spectroscopy (FTIR) and nuclear magnetic resonance of ¹H, ¹³C and ²⁹Si. The Cu(II)?CSila15NH was characterized by elemental analysis and FTIR. The straightforward Cu(II) complex formation suggests this property could be explored for analytical purposes.     

Speciation and complexation in aqueous Al(III)–quinolinate solutions: a spectroscopic study

Aqueous solutions containing quinolinic acid (2,3-pyridinedicarboxylic acid) and aluminum chloride were investigated using attenuated total reflection Fourier transform infrared spectroscopy, ²⁷Al nuclear magnetic resonance spectroscopy (²⁷Al NMR), and potentiometry. Conditional equilibrium constants were acquired at an apparent ionic strength of 1.33 M for the formation of quinolinic acid (H₂L), the HL⁻ species, and each of the Al(III)–quinolinate complexes (AlL⁺ and AlL₂ ⁻). The resolved infrared spectra of the quinolinate ion (L²⁻), the HL⁻ species, and quinolinic acid were assigned and interpreted with respect to the proton binding properties of the ligand. The assignments of the ²⁷Al NMR and infrared spectra of the Al(III)–quinolinate complexes provide evidence that quinolinate preferentially chelates to Al(III) through both the nitrogen of the pyridine ring and one of the oxygens of a carboxylate substituent.     

Renaissance patinas in Úbeda (Spain): mineralogic,petrographic and spectroscopic study

Different analytical techniques were used for microstructural and compositional analysis of the ochre-coloured patinas that appear on the calcarenite substrate of monuments in the historical settings of Úbeda and Baeza (Spain). Optical microscopy, scanning electron microscopy–energy dispersive x-ray spectrometry (SEM-EDX), x-ray diffraction, Raman spectroscopy and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) were employed and a critical comparison of their experimental requirements, strengths and weaknesses is presented. The study focussed on two churches in Úbeda where patinas were widespread in ornamental elements. These films contained calcite as the principal component, and traces of dolomite and feldspars. Clear identification of calcium oxalate, mainly in the form of whewellite, was achieved by infrared and Raman spectroscopic studies. Results from texture, distribution and composition of the patinas in ornamental elements suggest that ancient treatments were applied for protection of Renaissance façades and consolidation of weathered older façades. The patinas were seldom found on supporting elements. Their different composition, apatite was found together with oxalates, and location may suggest a biogenic origin here. Gypsum crusts were sometimes found over the patinas.     

The effect of the Co-anion,SCN−, on macrocycle-facilitated selective transport of Cd (II) over Ag (I) in an emulsion membrane

Emulsion membrane systems consisting of (1) an aqueous source phase containing 0.001 M Cd (NO₃)₂ and/or 0.001 M AgNO₃ and varying concentrations of SCN⁻, (2) a toluene membrane containing dicyclohexano-18-crown-6 (DC18C6) (0.02 M) and the surfactant Span 80 (sorbitan monooleate) (3% v/v), and (3) an aqueous receiving phase containing MgS₂O₃ or Mg (NO₃)₂ were studied with respect to the disappearance of Cd (II) and/or Ag (I) from the source phase as a function of time. The transport rate of Cd (II) was highest when a maximum amount of the Cd(II) in the source phase was present as Cd(SCN)₂ ([SCN⁻] =0.4 M). Cadmium(II) was transported over Ag(I), which is present mainly as Ag(SCN)₄³⁻, by 5- and 55-fold in 5 minutes with 0.4 M SCN⁻ in the source phase and 0.3 M S₂O²⁻₃ and 0.3 M NO⁻₃, respectively, in the receiving phase. In these competitive experiments, the total percent of Cd (II) transported was 98 and 84, respectively. The results are explained using the various equilibrium constants for cation-DC18C6, cation-SCN⁻ and cation-S₂O²⁻₃ interactions. These results indicate that rapid transport occurs when a cation is present in the source phase as a neutral complex. Selectivity for neutral species can be designed into these membrane systems when other cations interact with the source-phase anion to form charged species. Emulsion systems like those above were studied with respect to the appearance of Li⁺ in the source phase as a measure of membrane breakage. Maximum membrane stability was obtained when the ionic strengths of the source and receiving phases were equal.     

Inorganic Oxides with Immobilized Ferrozine and Ferene for the Sorption–Spectroscopic Determination of Iron(II)

Sorbents based on inorganic oxides sequentially modified with polyhexamethylene guanidine, ferrozine, and ferene S are proposed for the preconcentration and determination of iron(II). Upon sorption from solutions with pH 2.5–7.0, colored iron(II) complexes with ferrozine and ferene S, having broad bands with maxima at 560 and 600 nm in the diffuse reflectance spectrum, respectively, formed on the sorbent surface. Procedures for the sorption–photometric determination of iron(II) using diffuse reflectance spectroscopy were developed. The limits of detection for iron(II), calculated by the 3s criterion were 0.005 and 0.006 μg per 0.1 g for sorbents based on silica with immobilized ferrozine and ferene S, respectively. The linearity of calibration curves remains up to 5 and 10 μg per 0.1 g for sorbents based on silicon and aluminum oxides, respectively. The procedures were tested in the determination of the total iron concentration in bottled drinking waters and alcoholic drinks.     

Methods of the preconcentration of trace components: Development in Russia (1991–2010)

The main achievements of Russian scientists in recent decades in the fields of adsorption, solvent extraction, and other methods of the analytical preconcentration of inorganic and organic microcomponents are presented.     

Theoretical study of the thermodynamic parameters of (CaO)n nanoclusters with n = 2–16 in the gas and solution phases: proton affinity,molecular basicity,and pKb values

Structural Chemistry - Thermodynamic quantities such as proton affinity (PA) and molecular basicity (GB) for (CaO)n nanoclusters with n?=?2–16 have been calculated using three...     

A photophysical study of the interactions in poly(styrene-4-sulphonate)–n-butylvinylether block and random copolymers

Interactions between the moieties responsible for the conformations and hydrophobic microdomains in poly(styrene-4-sulphonate) (PSS) and its copolymers with n-butylvinylether (BVE) were studied by their emission spectra and the lifetimes of the phenyl groups and pyrene used as a photochemical probe. The emission spectra of PSS shows bands due to dimers and higher aggregates as well as the characteristic excimer band. At low concentrations, the random copolymers have spectra similar to that of the free monomer, whereas the block copolymers have spectra like that of PSS. At higher concentrations, the random copolymer also shows these excimer bands, due to interchain interactions. Results from the emission of pyrene prove that the behaviour of the copolymers with approximately 40% BVE seems to be relatively independent of having random or block configurations. Except at low concentrations (<0.05 g/dl), where the block copolymer already has a conformation with “stable” hydrophobic microdomains, both types of copolymers behave similarly. There is an initial aggregate equilibrium between individual chains and aggregates, associated with a relocation of the probes. At higher concentrations, both copolymers suffer a severe change in conformation, due to the formation of “stable” hydrophobic microdomains, resulting from interchain interactions. In both cases the lifetimes of pyrene are of the order of 240 ± 10 ns. Received: 27 August 1998 Accepted: 11 January 1999     

Theoretical study of group 11 metal–silonyl complexes: M–SiO and M–(SiO)2 (M = Cu, Ag, or Au)

 The spectroscopic properties of M–SiO and M–(SiO)₂ (1–1 and 1–2 complexes with M = Cu, Ag, or Au) have been theoretically studied. It has been shown that both M–SiO and M–(SiO)₂ compounds in their ground state are bent with a metal–Si bonded structure. The calculated M(ns) spin density agrees well with the electron spin resonance experimental data. From a topological analysis, it has been shown that a rather large charge transfer occurs from the metal towards the SiO moiety, and that the M–Si bond energy correlates with the electron density located at the M–Si bond path (bond critical point). Received: 6 July 2000 / Accepted: 11 October 2000 / Published online: 19 January 2001     

Analytical control of environmental samples in the Russian federation (1991–2010)

The review presents studies of Russian scientists in the past 20 years concerning the analytical control of environmental samples. A special attention is paid to the directions where the most interesting results were obtained or new methods of analysis and sample treatment were proposed; also pollutants that require the application of the most modern analytical methods are considered.     

Interplay of thermochemistry and Structural Chemistry: the journal (volume 29, 2018, issues 5–6) and the discipline

The contents of issues 5 and 6 of Structural Chemistry from the calendar year 2018 are summarized in the present review. A brief thermochemical commentary and recommendations for future research have been added to the summary of each paper.

     

Interplay of thermochemistry and Structural Chemistry: the journal (volume 29, 2018, issues 1–2) and the discipline

Structural Chemistry - The contents of issues 1 and 2 of Structural Chemistry from the calendar year 2018 are summarized in the present review. A brief thermochemical commentary and recommendations...     

Sorption of organic liquids in poly(ethylene chlorotrifluoroethylene) Halar®901: Experimental and theoretical analysis

Sorption of liquids in polymers is an important factor for any application where polymers come into contact with an organic solvent. We report on sorption properties of hydrophobic poly(ethylene chlorotrifluoroethylene) Halar^®901 in view of its potential application as a membrane material. For the first time, the liquid phase sorption of 34 common organic liquids such as linear C₆C₁₀ alkanes, methyl-, ethyl- and propyl-derivates of benzene and cyclohexane and of linear-, branched- and cyclic-ethers, ketones, acetates and chloroderivates in the 1:1 alternating copolymer of ethylene and chlorotrifluoroethylene (ECTFE) is presented. The effects of solvent molecular structure and its physico-chemical properties on the total mass uptake are discussed in detail. Furthermore, two sorption-predictive methods developed from determined data allows to anticipate the behavior of solvents in Halar^®901 based exclusively on three type of structural units (C-bone, functional groups, molecular geometry) or four (molar mass, surface tension, boiling temperature and Van der Waals volume) parameters only. A successful verification of our methods proved their versatility in predicting organic liquid sorption in ECTFE material Halar^®901.