Synthesis of New Polysiloxane-Immobilized Ligand System Di(amidomethyl)aminetetraacetic Acid

A new chelating porous polysiloxane-immobilized tetraacetic acid ligand system has been prepared. This material was made by chemical modification of the iminodiacetic acid polysiloxane with thionyl chloride and diethyliminodiacetate, respectively. The polysiloxane functionalized with di(amidomethyl)aminetetraacetic acid of the general formula P-(CH ₂ ) ₃ N(CH ₂ C(O)N) ₂ (CH ₂ COOH) ₄ [where P represents the polysiloxane backbones (Si?O?Si) _n ] was characterized by Thermogravimetric Analysis (TGA) and FTIR spectra. The FTIR results proved that tetraacetic acid groups are successfully grafted onto the polysiloxane surface. This ligand system exhibits high potential for extraction of divalent metal ions (Co⁺², Ni⁺², Cu⁺², and Zn⁺²) from aqueous solution.     

Synthesis and Characterization of Hydrogels Based on Gamma Radiation Copolymerization of N‐isopropylacrylamide and Ethylene Glycol Dimethacrylate Monomers

Hydrogels based essentially on N‐isopropylacrylamide (NIPAAm) and different ratios of ethylene glycol dimethacrylate (EGDMA) monomer were synthesized by gamma radiation copolymerization. The thermal decomposition behavior of NIPAAm/EGDMA hydrogels was determined by thermogravimetric analysis (TGA). The effect of temperature and pH on the swelling behavior was also studied. The results showed that the ratio of EGDMA in the comonomer feeding solution has a great effect on the yield product, gel fraction and water content in the final hydrogel. In this regard, it was observed that the increase of EGDMA ratio decreased these properties. The TGA study showed that all the compositions of NIPAAm/EGDMA hydrogels displayed higher thermal stability than the hydrogel based on pure PNIPAAm hydrogel. The swelling kinetics in water showed that pure PNIPAAm and NIPAAm/EGDMA hydrogels reached equilibrium after 6 h. However, NIPAAm/EGDMA hydrogels show swelling in water lower than pure PNIPAAm. The results showed that the swelling character of pure PNIPAAm and NIPAAm/EGDMA hydrogels was affected by the change in temperature within the temperature range 25–40°C, and showed a reversible change in swelling in the pH range 4–7 depending on composition.     

Deposition and characterization of carbon nitride films from hexamethylenetetramine/N2 by microwave plasma-enhanced chemical vapor deposition

Carbon nitride thin films were deposited on Si(1 0 0) substrate by microwave plasma-enhanced chemical vapor deposition (PECVD). Hexamethylenetetramine (HMTA) was used as carbon and nitrogen source while N₂ gas was used as both nitrogen source and carrier gas. The sp³-bonded C---N structure in HMTA was considered significantly in the precursor selection. X-ray diffraction analysis indicated that the film was a mixture of crystalline - and β-C₃N₄ as well as graphitic-C₃N₄ and β-Si₃N₄ which were not easily distinguished. Raman spectroscopy also suggested the existence of - and β-C₃N₄ in the films. X-ray photoelectron spectroscopy study indicated the presence of sp²- and sp³-bonded C---N structures in the films while sp³C---N bonding structure predominated to the sp² C---N bonding structure in the bulk composition of the films. N was also found to be bound to Si atoms in the films. The product was, therefore, described as CN_x:Si, where x depends on the film depth, with some evidences of crystalline C₃N₄ formation.     

Nanoindentation of Teeth-A Review

0Introduction Oneofthemostimportantrolesofteethismastication.Thismasticationprocesscanexertgreat amountofrepetitiveforcesontheteethandaffecttheirstructuralintegrity.Also,intheprocessof consumption,teetharefrequentlyexposedtoallkindsofliquidandthismayagaininfluencetheir mechanicalpropertiesandperformance[1].Certainteeth relateddiseases[2]anddentaltreatmentsuch asbleachingarealsoknowntogreatlyaffectthestructuralintegrityandmechanicalpropertiesof teeth.Assuch,numerousresearchworkshavebeendonetoe…     

Polysiloxane-Immobilized Triamine Ligand System,Synthesis and Applications

The polysiloxane-immobilized triamine ligand system of the formula P-(CH 2 ) 3 NH(CH 2 ) 2 NH(CH 2 ) 2 NH 2 (where P represents the siloxane network) has been prepared via the sol-gel process by hydrolytic polycondensation of (EtO) 4 Si and (MeO) 3 Si(CH 2 ) 3 NH(CH 2 ) 2 NH(CH 2 ) 2 NH 2 . An alternative method was used by the reaction of the iodopolysiloxane P-(CH 2 ) 3 -I and diethylenetriamine in the presence of triethylamine. The immobilized triamine ligand forms metal chelate complexes when treated with aqueous metal(II) ion solutions (Co 2+ , Ni 2+ , and Cu 2+ ). The elemental analysis and FTIR results suggest that this ligand system undergoes a substantial leaching of diethylenetriamine ligand moieties from the siloxane framework.     

Guidelines for dynamics‐based parameterization of one‐dimensional cellular automata rule spaces

As paradigmatic complex systems, various studies have been done in the context of one‐dimensional cellular automata (CA) on the definition of parameters directly obtained from their transition rule, aiming at the help they might provide to forecasting CA dynamic behavior. Out of the analysis of the most important parameters available for this end, as well as others evaluated by us, a set of guidelines is proposed that should be followed when defining a parameter of that kind. Based upon the guidelines, a critique of those parameters is made, which leads to a set of five that jointly provide a good forecasting set; two of them were drawn from the literature and three are new ones defined according to the guidelines. By using them as a heuristic in the evolutionary search for CA of a predefined computational behavior, good results have been obtained, exemplified herein by the evolutionary search for CA that perform the Synchronization Task. © 2001 John Wiley & Sons, Inc.     

Ion exchange test for microgram detection of mercaptans

A spot test for the detection of mercaptans is based on the reaction with sodium nitroprusside in the presence of an anion-exchange resin in OH^? form, to give a pink color on a resin bead surface.     

Synthesis of Fe- or Ag-doped TiO2–MWCNT nanocomposite thin films and their visible-light-induced catalysis of dye degradation and antibacterial activity

Research on Chemical Intermediates - Thin films of TiO2, TiO2-multiwalled carbon nanotubes (TiO2–MWCNT), Fe-doped TiO2–MWCNT (Fe–TiO2–MWCNT), and Ag-doped TiO2–MWCNT...     

Preconcentration and Separation of Copper(II) by 3-Aminopropylpolysiloxane Immobilized Ligand System

Porous solid insoluble polysiloxane-immobilized ligand system bearing propylamine of the general formula P-(CH₂)₃-NH₂ (where P represents [Si–O]_n siloxane network) was prepared and evaluated for the separation and preconcentration of copper(II) from aqueous solution. The ligand system retained Cu(II) effectively when used as a metal ion extractant. The ligand system also showed high selectivity to separate copper(II) from a mixture of metal ions (Co(II), Ni(II), Cu(II)) when used as chromatographic stationary phase. The optimum pH appeared to be pH = 5.5 using acetate buffer as an eluent. Thermal analysis showed that the ligand system is very stable at relatively high temperatures.     

UV-Promoted Metal- and Photocatalyst-Free Direct Conversion of Aromatic Aldehydes to Nitriles

Russian Journal of Organic Chemistry - An efficient, simple, and catalyst-free UV-induced functional group transformation of aromatic aldehydes to nitriles has been reported. The developed strategy...