Intermediate products in solid‐state reactions of gadolinium oxide and ammonium dihydrogen phosphate

The solid‐state reactions of Gd₂O₃ with NH₄H₂PO₄ using various molar ratios (3:6, 2:8, 1:6 and 1:8) of the reactants were investigated at different temperatures (350‐1100°C) to observe the intermediate compounds. Analysis of the X‐ray powder diffraction patterns of the products obtained at 350°C; for the compositions of 2:8, 1:6 and 1:8 molar ratios revealed the formation of a new compound, NH₄GdHP₃O₁₀ which was reported previously for Nd, Ho and Er. At higher temperatures, gadolinium tripolyphosphate was obtained for all of the molar ratios. On the other hand, the IR data of the products also confirmed the proposed reaction pathways. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effects of OCRA parameters and learning rate on machine scheduling

Central European Journal of Operations Research - In this paper, the effects of Occupational Repetitive Actions (OCRA) parameters, learning rate on process times, and machine scheduling were...     

Encapsulation and release by star‐shaped block copolymers as unimolecular nanocontainers

A five‐arm star‐shaped poly(ethylene oxide) (PEO) with terminal bromide groups was used as a macroinitiator for the atom transfer radical polymerization of tert‐butyl acrylate (tBA), resulting in five‐arm star‐shaped poly(ethylene oxide)‐block‐poly(tert‐butyl acrylate) block copolymers. The polymerization proceeded in a controlled way using a copper(I)bromide/pentamethyl diethylenetriamine catalytic system in acetonitrile as solvent. The hydrolysis of the tBA blocks of the amphiphilic star‐shaped PEO‐b‐PtBA block copolymer resulted in dihydrophilic star structures. The encapsulation of the star‐block copolymers and their release properties in acid environment have been followed by UV‐spectroscopy and color changes, using the dye methyl orange as a hydrophilic guest molecule. Characterization of the structures has been done by ¹H NMR, size exclusion chromatography, MALDI‐TOF, and differential scanning calorimetry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 650–660, 2008     

Observations on quasi-uniform products

We prove that any product of quotient maps in the category of quasi-uniform spaces and quasi-uniformly continuous maps is a quotient map. We also show that a quasi-uniformly continuous map from a product of quasi-uniform spaces into a quasi-pseudometric T₀-space depends on countably many coordinates.Furthermore we characterize those quasi-uniformities that are unique in their quasi-proximity class and prove that this property is preserved under arbitrary products in the category of quasi-uniform spaces.     

Ethynyl-bridged porphyrin-corrole dyads and triads: Synthesis,properties and DFT calculations

Ethynyl-bridged porphyrin-corrole dyads and triads were synthesized by using Pd(0) mediated coupling reactions and their structures were characterized by NMR, FT-IR, UV/Vis and fluorescence techniques. Besides spectroscopic techniques, computational studies at B3LYP/6-311G(d,p) level of DFT were also used to elucidate the minimum energy geometries and the molecular orbital characteristics of the new dyads and triads. DFT calculations pointed out the presence of charge separated donor-acceptor property between macrocycles of dyads and triads, and the emission studies indicated an excited state interaction between macrocycles, and energy transfer from the porphyrin to the corrole unit.     

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL PROPERTIES OF 4-[（4-HYDROXYBENZYLIDENE） AMINO] PHENOL AND ITS POLYMER

The oxidative polycondensation reaction conditions of 4-[(4-hydroxybenzylidene)amino]phenol(4-HBAP)were studied with H_2O_2,air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90℃.The structures of the obtained monomer and polymer were confirmed by FT-IR,UV-Vis,~1H-and ~(13)C-NMR and elemental analysis.The characterization was made by TG-DTA,size exclusion chromatography(SEC)and solubility tests.At the optimum reaction conditions,the yield of poly[4-(4-hydroxybenzylidene amino)phenol](P-4-HBAP)was found to be 48.3%(for H_2O_2 oxidant),80.5%(for air O_2 oxidant)and 86.4%(for NaOCl oxidant).According to the SEC analysis,the number-average molecular weight(M_n),weight-average molecular weight(M_w)and polydispersity index(PDI)values of P-4-HBAP was found to be 8950,10970 g mol~(-1) and 1.225,respectively,using H_2O_2;and 11610,15190 g mol~(-1) and 1.308 respectively, using air O_2 and 7900,9610 g mol~(-1) and 1.216,respectively,using NaOCl.According to TG-DTA analyses,P-4-HBAP was more stable than 4-HBAP against thermal decomposition.The weight loss of P-4-HBAP was found to be 49.27% at 1000℃. The highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)values calculated from electrochemical measurement.Electrochemical energy gaps(E′_g)of 4-HBAP and P-4-HBAP were found to be-5.46, -5.28;-2.26,-2.67;3.20 and 2.61 eV,respectively.According to UV-Vis measurements,optical band gap(E_g)of 4-HBAP and P-4-HBAP were found to be 3.34 and 3.01 eV,respectively.Also,antimicrobial activities of 4-HBAP and P-4-HBAP were examined against selected some bacteria.The electrical conductivity of the polymer was measured after doping with iodine.     

Use of a Packed Minicolumn Connected to a Syringe for Determination of Trace Elements in Biological and Water Samples by Flame Atomic Absorption Spectrometry

In this study, a syringe-connected minicolumn resin was used for the separation and enrichment of cadmium, copper, nickel and zinc prior to their determination by flame atomic absorption spectrometry. The proposed technique was compared with classical batch and column techniques in terms of rapidness, simplicity, enrichment and risk of contamination. The minicolumn was filled with Chromosorb-103 resin and connected to a syringe. If the samples were treated with ammonium pyrrolidine dithiocarbamate or 8-hydroxyquinoline, the analytes were quantitatively retained at pH2 and pH5 on the resin, respectively. On the other hand, if no chelating agent was added, the analytes were quantitatively retained at pH10. The analytes retained by the resin were quantitatively eluted by drawing and discharging nitric acid in acetone. The analytes in spiked river-water samples and in certified standard reference Bovine-Liver (NIST SRM 1577 b) were quantitatively (94%) recovered. The relative standard deviations for the determinations were found to be 1.0–10%.     

Synthesis of a novel crosslinked superabsorbent copolymer with diazacyclooctadecane crown ether and its sorption capability

A novel crosslinked poly(acrylic acid-copolymer-Kryptofix-22-DM) superabsorbent copolymer, poly(AA-co-Kry22-DM), was synthesised by the reaction of 4,13-dimethylacryloyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (Kyrptofix-22-DM) and acrylic acid (AA). Characterisation of the polymers was achieved by FTIR and ¹H NMR techniques. Sorption capacity of the crosslinked poly(AA-co-Kry22-DM) superabsorbent copolymer was investigated for Pb²⁺, Cu²⁺, Cr³⁺, Cd²⁺, Mn²⁺, Zn²⁺, and Ni²⁺ heavy metal ions at different pH values using Freundlich and Langmuir isotherms. Swelling ratio, q_v, and distribution ratio, log D, values of the crosslinked poly(AA-co-Kry22-DM) superabsorbent copolymer were calculated at various pH values.     

Determination of fingerprints contents of different extracts and parts of six endemic Salvia taxa by GC–MS: Source species for valuable compounds with drug or drug potential

Public use of Salvia species and their importance in the scientific world is continually increasing. It is known that this use and the importance of Salvia species are mostly due to the terpenoid compounds that they contain. In this context, the terpenoid–steroid–flavonoid contents of extracts of six endemic Salvia (S. kurdica, S. pseudeuphratica, S. rosifolia, S. siirtica, S. cerino-pruinosa var. cerino-pruinosa and S. cerino-pruinosa var. elazigensis) species prepared with different solvents were determined by gas chromatography–mass spectrometry. Within the framework of the ingredient analysis, content analysis of the ethanol extracts of the root, branch, leaf and flower parts of the species collected in the same period between 2015 and 2017 years was performed. In general, extracts prepared with chloroform and ethanol were found to contain a wide variety of compounds while petroleum ether extracts were found to contain much less varied compounds. In addition, in general, root extracts are richer in terpenoid compounds than aerial part extracts. Some species can be used as source species in terms of ferruginol, cryptanol, 6,7-dehydroroyleanone, lup-(20)29-ene-2α-hydroxy-3β-acetate, salvigenin and β-sitosterol contents (52,114.28, 75,979.08, 101,247.41, 40,071.29, 33,952.13 and 34,010.90 μg analyte/g extract, respectively).     

Preparation and characterization of a novel diatomite-based composite and investigation of its adsorption properties for uranyl ions

Journal of Radioanalytical and Nuclear Chemistry - The thiol-functional hydrotalcite (Mg/Al-LDO-SH) composite materials were prepared and characterized by EDS, SEM, FT-IR and XRD. The variables...