Metric and Complete Metric σ-Frames

A -frame is a lattice in which countable joins exist and binary meets distribute over countable joins. In this paper, the category MFrm, of metric -frames, is introduced, and it is shown to be equivalent to the category MLFrm _u, of metric Lindelöf frames.Finally, it is shown that the complete metric -frames are exactly the cozero parts of complete metric Lindelöf frames.     

A selective sensor for nanolevel detection of lead (II) in hazardous wastes using ionic-liquid/Schiff base/MWCNTs/nanosilica as a highly sensitive composite

An effective potentiometric sensor had been fabricated for the rapid determination of Pb²⁺ based on carbon paste electrode consisting of room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆), multiwalled carbon nanotubes (MWCNTs), nanosilica, synthesized Schiff base, as an ionophore, and graphite powder. The constructed nanocomposite electrode showed better sensitivity, selectivity, response time, response stability, and lifetime in comparison with typical Pb²⁺ carbon paste electrode for the successfully determination of Pb²⁺ ions in water and in waste water samples. The best response for nanocomposite electrode was obtained with electrode composition of 18% ionophore, 20% BMIM-PF₆, 49% graphite powder, 10% MWCNT, and 3% nanosilica. The new electrode exhibited a Nernstian response (29.76?±?0.10 mV decade^?1) toward Pb²⁺ ions in the range of 5?×?10^?9?C1.0?×?10^?1 mol L^?1 with a detection limit of 2.51?×?10^?9 mol L^?1. The potentiometric response of prepared sensor is independent of the pH of test solution in the pH range of 4.5?C8.0. It has quick response with response time of about 6 s. The proposed electrode show fairly good selectivity over some alkali, alkaline earth, transition, and heavy metal ions.     

Effect of Different Purification Techniques on the Characteristics of Heteropolysaccharide-Protein Biopolymer from Durian (<em>Durio zibethinus</em>) Seed

Natural biopolymers from plant sources contain many impurities (e.g., fat, protein, fiber, natural pigment and endogenous enzymes), therefore, an efficient purification process is recommended to minimize these impurities and consequently improve the functional properties of the biopolymer. The main objective of the present study was to investigate the effect of different purification techniques on the yield, protein content, solubility, water- and oil-holding capacity of a heteropolysaccharide-protein biopolymer obtained from durian seed. Four different purification methods using different chemicals and solvents (i.e., A (isopropanol and ethanol), B (isopropanol and acetone), C (saturated barium hydroxide), and D (Fehling solution)] to liberate the purified biopolymer from its crude form were compared. In most cases, the purification process significantly (p < 0.05) improved the physicochemical properties of heteropolysaccharide-protein biopolymer from durian fruit seed. The present work showed that the precipitation using isopropanol and acetone (Method B) resulted in the highest purification yield among all the tested purification techniques. The precipitation using saturated barium hydroxide (Method C) led to induce the highest solubility and relatively high capacity of water absorption. The current study reveals that the precipitation using Fehling solution (Method D) most efficiently eliminates the protein fraction, thus providing more pure biopolymer suitable for biological applications.     

Synthesis of Alkyl (5-Oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates by the Reaction of N-Aminorhodanine,Dialkyl Acetylenedicarboxylates,and Triphenylphosphine

Protonation of the reactive zwitterionic intermediate produced from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by N-aminorhodanine followed by the addition of the conjugate anion of N-aminorhodanine on the produced vinylphosphonium cation leads to alkyl (5-oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates in good yields.     

A New Complex as a Dimer of a Silver Ion with AMTTO and Phosphane Ligands. The Crystal Structure of {[(AMTTO)Ag(PPh3)2]NO3}2·0.5CH3OH·0.5H2O

Reaction of 4‐amino‐6‐methyl‐1,2,4‐triazine‐3‐thione‐5‐on (AMTTO) as a bidentate ligand with silver nitrate and triphenyl phosphine as the co‐ligand make the centrosymmetric dimeric complex {[(AMTTO)Ag(PPh₃)₂]NO₃}₂·0.5CH₃OH·0.5H₂O ( 1 ). 1 was characterized by elemental analyses, IR‐ and NMR spectroscopy as well as X‐ray diffraction studies. The silver atom in 1 has distorted tetrahedral coordination. 1 crystallizes in triclinic space group . Crystal data for 1 at −80 °C: a = 1185.8(1), b = 1314.6(1), c = 1385.3(1) pm, α = 97.78(1)°, β = 111.38(1)°, γ = 92.41(1)°, Z = 2, R₁ = 0.0377.     

Crystal and Molecular Structures of Mononuclear Coordinated Copper(I) Complexes with Thio-triazole and Thio-triazine based Schiff base Ligands

Reaction of 4-amino-5-methyl-1,2,4-triazol-3(2H)-thione (AMTT) and 4-amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one (AMTTO) with 2-hydroxybenzaldehyde led to the synthesis of corresponding Schiff base ligands [(Z)-4-((2-hydroxybenzylidene)amino)-3-methyl-1H-1,2,4-triazole-5(4H)-thione ( L1 ) and (Z)-4-((2-hydroxybenzylidene)amino)-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one ( L2 )]. Treatment of synthesized Schiff base ligands with CuCl provided the complexes [Cu(L1)₃Cl] ( 1 ) and [Cu(L2)₂Cl] ( 2 ). Synthesized complexes were characterized by elemental analyses, IR spectroscopy and X-ray diffraction studies. Complex 1 consists of a metal ion coordinated with one chloride ion and three Schiff base ligands via sulfur atoms in a distorted tetrahedral environment, whereas 2 consists of a metal ion coordinated with one chloride ion and two sulfur atoms from two different Schiff base ligands in a trigonal planar arrangement. Crystal data for 1 at –153 °C revealed an orthorhombic space group Fdd2, a = 34.8088(7), b = 33.8156(8), c = 11.6142(2) Å, Z = 16, R₁ = 0.0357; for 2 at –178 °C the symmetry was triclinic, space group P1 , a = 7.27520(10), b = 15.4620(2), c = 23.7985(4) Å, α = 72.1964(13), β = 86.5208(12), γ = 89.8597(11)°, Z = 4, R₁ = 0.0359.     

Catalytic effect of lucunary heteropolyanion containing molybdenum and tungsten atoms on decolorization of direct blue 71

In this research,a lucunary Keggin structure,[PMo₂W₉O₃₉]^7- was selected as an efficient homogenous catalyst for degradation of an azo dye（direct blue 71） and a simple method was developed for degradation of DB71.The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K₇[PMo₂W₉O₃₉]? 19H₂O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H₂O₂,pH and reaction time were investigated and optimized. Results show that K₇[PMo₂W₉O₃₉]? 19H₂O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H₂O₂ could lead to the disappearance approximately 65%of dye after 60 min.But degradation for the same experiment performed in the absence of catalyst or in the absence of H₂O₂ was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H₂O₂ and optimize conditions(0.6 g/L of K₇[PMo_2- W₉O₃₉H₉H₂O,0.08 mol/L hydrogen peroxide and room temperature).     

Syntheses,Characterization and X‐ray Structure of the First Silver(I) Complexes with 4‐Amino‐3‐thioxo‐3,4‐dihydro‐1,2,4‐triazin‐5(2H)‐one

Reaction of thiocarbohydrazide with glyoxolic acid monohydrate led to 4‐amino‐3‐thioxo‐3,4‐dihydro‐1,2,4‐triazin‐5(2H)‐one (AHTTO, 1 ). Treatment of 1 with AgNO₃ and PPh₃ gave thecomplexes [(PPh₃)₂Ag₂(μ‐N,S‐AHTTO)₂](NO₃)₂ ( 2 ) and [(PPh₃)₂Ag(AHTTO)]NO₃ · MeOH ( 3 ) was obtained under different conditions. All the compounds have been characterized by elemental analyses, IR spectroscopy and X‐ray diffraction studies.     

Design and synthesis of new 2-substituted-5-[2-(2-halobenzyloxy)phenyl]-1,3,4-oxadiazoles as anticonvulsant agents

A new series of 2-substituted-5-[2-(2-halobenzyloxy)phenyl]-1,3,4-oxadiazoles was designed and synthesized as anticonvulsant agents. Electroshock and pentylenetetrazole-induced lethal convulsion tests showed that the introduction of an amino group at position 2 of 1,3,4-oxadiazole ring and a fluoro substituent at ortho position of benzyloxy moiety had the best anticonvulsant activity. Our results showed that this effect is mediated through benzodiazepine receptors mechanism.