Mass spectrometric study of the thermal decomposition mechanism of vapors of 2,2,6,6-tetramethyl-3-iminoheptane-5-one and its copper(II) complex

Thermal conversions of vapors of ketoimine C(CH₃)₃C(NH)CH₂C(O)C(CH₃)₃ (Htmha = 2,2,6,6-tetramethyl-3-iminoheptane-5-one) and its chelate coordination compound with copper Cu(tmha)₂ is studied by in situ mass spectrometry in a vacuum and in the presence of hydrogen. Experiments are carried out under conditions close to low pressure chemical vapor deposition at the evaporator temperature of 130 °C and the reactor temperature range 130-500 °C. It is found that compounds are monomeric in the gas phase. Based on temperature dependences of the composition of primary gaseous products, the mechanism of thermal decomposition is proposed. The decomposition of ketoimine on the heated surface begins at 350 ± 10 °C and proceeds by the elimination of terminal groups. Its copper complex decomposes in two directions and yields both molecular and radical products. The latter provide the assumption that metallic copper forms as the only one solid product. The results obtained are compared with those for copper dipivaloylmethanate(2,2,6,6-tetramethylheptane-3,5-dionate).     

Thermal and FTIR analysis of the miscibility and phase behaviour of poly (isobutyl methacrylate-co-4-vinylpyridine)/poly (styrene-co-acrylic acid) systems

The miscibility and phase behaviour of poly (isobutyl methacrylate-co-4-vinylpyridine) containing 20 mol% of 4-vinylpyridine (IBM4VP20) and poly (styrene-co-acrylic acid) containing 27 or 32 mol% of acrylic acid (SAA27 or SAA32) mixtures were investigated by DSC, TGA and FTIR spectroscopy in the 25–180 °C temperature range. The results showed that sufficient specific carboxyl–pyridine hydrogen bonding interactions occurred between these copolymers and led to miscible blends as cast from THF and to inter-polymer complexes of significantly improved thermal stability when butan-2-one is the common solvent. The self-association effect on the inter-polymer interactions was evidenced by the decrease of complexation yields, observed when the carboxylic content is increased above 27 mol% as with SAA32.The trend of phase behaviour predicted by a thermodynamic analysis of the specific interactions of hydrogen bonding type that occurred between the two components of the SAA27/IBM4VP20 blends, neglecting the weak carboxyl–ester interactions and the functional group accessibility effect, carried out using the Painter–Coleman association model that considers the screening effects, is in a fair agreement with the experimental results. Moreover an LCST is predicted to occur at relatively high temperature.     

Synthesis and structural characterization of the dinuclear bis(glutarato)bis(urea)copper(II)complex, dihydrate

The complex [Cu(OOC-(CH₂)₃-COO)(O=C(NH₂)₂]₂·2H₂O has been synthesized and characterized by X-ray crystallography. It crystallizes in the triclinic system P-1 with a = 8.003(2) ?, b = 8.611(2) ?, c = 8.620(2) ?, α = 96.14(3)°, β = 116.66(2)°, γ = 105.66(4)° and V = 492.9(3) ?³. The structure consists of discrete centrosymmetric binuclear units and water molecules. The Cu(II) ions adopt a square-pyramidal coordination with four oxygen atoms of four bridging carboxylate and one carbonyl oxygen of the monodentate urea ligand. There is a very strong interaction between the two copper centers in binuclear entities (CuCu: 2.6266(15) ?).     

A new Carleman inequality for parabolic systems with a single observation and applications

In this Note, we present Carleman estimates for linear reaction–diffusion–convection systems of two equations and linear reaction–diffusion systems of three equations. These estimates are the key for proving controllability results for semilinear reaction–diffusion–convection systems of order 2 and reaction–diffusion systems of order 3. They allow us to derive results for identification of n coefficients by $(n?2)$ observations.     

Synthesis and crystal structure of bis(malonato)tetra (aqua)barium(II)cobalt(II): [BaCo(C<Subscript>3</Subscript>H<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>]

The title compound [BaCo(C₃H₂O₄)₂(H₂O)₄] was synthesized and its crystal structure was determined. The compound is orthorhombic, space group Pccn with a = 18.974(3) Å, b = 6.783(2) Å, c = 9.394(4) Å. The structure is polymeric and consists of edge-sharing BaO₈ polyhedra and CoO₆ octahedra linked together by the malonate groups. The geometry around the Ba(II) centres is a slightly distorted square-antiprism with Ba–O distances ranging from 2.789(4) to 2.843(4) Å. Around the Co(II) centres, the coordination forms a distorted octahedron with Co–O bonds between 2.040(3) and 2.238(4) Å.     

Null-controllability of some reaction–diffusion systems with one control force

This work is concerned with the null-controllability of semilinear parabolic systems by a single control force acting on a subdomain.     

A decisional framework system for computer network intrusion detection

This paper presents a multi-attribute decisional framework for computer network intrusion detection. First, a cost model that allows to estimate accurately the damage resulting from a security incident is described. Then, a multi-attribute optimization algorithm is applied to select the optimal decision based on alternatives to remedy such incidents.     

Stress–strain behavior of low‐density polyethylene/poly(methyl methacrylate) blends with modulated interfaces with a hydrogenated polybutadiene‐block‐poly(methyl methacrylate) diblock copolymer

The stress–strain diagrams and ultimate tensile properties of uncompatibilized and compatibilized hydrogenated polybutadiene‐block‐poly(methyl methacrylate) (HPB‐b‐PMMA) blends with 20 wt % poly(methyl methacrylate) (PMMA) droplets dispersed in a low‐density polyethylene (LDPE) matrix were studied. The HPB‐b‐PMMA pure diblock copolymer was prepared via controlled living anionic polymerization. Four copolymers, in terms of the molecular weights of the hydrogenated polybutadiene (HPB) and PMMA sequences (22,000–12,000, 63,300–31,700, 49,500–53,500, and 27,700–67,800), were used. We demonstrated with the stress–strain diagrams, in combination with scanning electron microscopy observations of deformed specimens, that the interfacial adhesion had a predominant role in determining the mechanism and extent of blend deformation. The debonding of PMMA particles from the LDPE matrix was clearly observed in the compatibilized blends in which the copolymer was not efficiently located at the interface. The best HPB‐b‐PMMA copolymer, resulting in the maximum improvement of the tensile properties of the compatibilized blend, had a PMMA sequence that was approximately half that of the HPB block. Because of the much higher interactions encountered in the PMMA phase in comparison with those in HPB (LDPE), a shorter sequence of PMMA (with respect to HPB but longer than the critical molecular weight for entanglement) was sufficient to favor a quantitative location of the copolymer at the LDPE/PMMA interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 22–34, 2005