Synthesis and magnetic properties of heteronuclear 3d-4f compound

A novel heteronuclear 3d-4f compound having formula NdCu3L3·13H2O (where H3L = Schiff base derived from 5-bromosalicylaldehyde and glycylglycine and L³ = C11H8 N2O4Br) was obtained. It was characterized by elemental and thermal analyses and magnetic measurements. The Cu(II)-Nd(III) compound is stable up to 323 K. During dehydration process the water molecules are lost in two stages. The magnetic susceptibility data for this complex change with temperature according to the Curie-Weiss law with theta = -35 K. The magnetic moment values decrease from 5.00µB at 303 K to 4.38µB at 76 K.

The physico-chemical properties of 4-chlorophenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II)

The complexes of 4-chlorophenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II) have been synthesized as polycrystalline solids, and characterized by elemental analysis, spectroscopy, magnetic studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: pink for Co(II), green for Ni(II), blue for Cu(II) and a pale pink for Mn(II) compounds. The carboxylate group binds as monodentate and bidentate ligands. On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to anhydrous salts, that next decompose to the oxides of respective metals. Their magnetic moments were determined in the range of 76-303K. The results reveal them to be high-spin complexes of weak ligand fields.

Analysis of the structural and electronic properties of 1-(5-Hydroxymethyl - 4 -[ 5 - (5-oxo-5-piperidin-1-yl-penta-1,3dienyl)-benzo[1,3]dioxol-2-yl] -tetrahydro-furan-2-yl)-5-methyl-1H-pyrimidine-2,4dione molecule

The structural and electronic properties of 1-(5-Hydroxymethyl - 4 -[ 5 - (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]-tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.

Comparison of some properties of 2,3 - and 3,4 - dimethoxybenzoates of Cu(II), Co(II) and Nd(III)

The physicochemical properties of 2,4-, and 3,4- dimethoxybenzoates of Cu(II), Co(II) and Nd(III) were studied and compared to observe the -OCH3 substituent positions in benzene ring on the character of complexes. The analysed compounds are crystalline hydrated or anhydrous salts with colours depending on the kind of central ions: blue for Cu(II), pink for Co(II) and violet for Nd(III) complexes. The carboxylate groups bind as monodentate, bidentate bridging or chelating and even tridentate ligands. Their thermal stabilities were studied in air at 293-1173K. When heated the hydrated complexes release the water molecules and form anhydrous compounds which are then decomposed to the oxides of respective metals. Their magnetic moment values were determined in the range of 76-303K. The results reveal the compounds of Nd(III) and Co(II) to be the high-spin and that of Cu(II) forms dimer. The various positions of -OCH3 groups in benzene ring influence some of physicochemical properties of analysed compounds.

Biheterocyclic ligands: synthesis, characterization and coordinating properties of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes with transition metal ions and their thermokinetic and biological studies

The Co(II), Ni(II) and Cu(II) metal ions complexes of Bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes (BATs) have been prepared and characterized by elemental analysis, conductivity measurements infrared, magnetic susceptibility, the electronic spectral data and thermal studies. Based on spectral and magnetic results, the ligands are tetradentate coordinating through the N and S-atoms of BATs; six-coordinated octahedral or distorted octahedral and some times four-coordinated square planar were proposed for these complexes. Activation energies computed for the thermal decomposition steps were compared. The ligands and their metal complexes were tested in vitro for their biological effects. Their activities against two gram-positive, two gram-negative bacteria and two fungal species were found to vary from moderate to very strong.

Electrochemical properties of Cu4[PhN3C6H4N3(H)Ph]4(µ-O)2, a tetranuclear Copper(II) complex with 1-phenyltriazenido-2-phenyltriazene-benzene as ligand

Bis-(µ2-oxo)-tetrakis{[1-feniltriazene-1,3-diil)-2-(phenyltriazenil)benzene copper(II) is a tetranuclear complex which shows four Cu(II) ions coordinated by four 1,2-bis(phenyltriazene)benzene bridged ligands, with one diazoaminic deprotonated chain, and two O2- ligands. The complex reduces at E1/2 = -0.95 V vs Fc+/Fc, a two electrons process. Cyclic voltammetric and spectroelectrochemical studies showed a reversible process. When immobilized on carbon paste electrode, the complex electrocatalyses the reduction of O2 dissolved on aqueous solution at -0.3 V vs SCE potential. The obtained current shows linearity with O2 concentration.

Thermal and spectral properties of di-and trimethoxybenzoates of silver (I)

The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4- and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3.

Therapeutic Properties of Superoxide Dismutase 3 and Mesenchymal Stromal Cells in Peripheral Ischemia

The aim of this study was to characterize the cellular mechanisms leading to the beneficial effect of anti-oxidative gene therapy and pro-angiogenic stem cell therapy in acute peripheral ischemia. Post-ischemic events aim to re-establish tissue blood perfusion, to clear cellular debris, and to regenerate lost tissue by differentiation of satellite cells into myoblasts. Although leukocytes have an essential role in clearing cellular debris and promoting angiogenesis, they also contribute to tissue injury through excessive ROS production. First, we investigated the therapeutic properties of extracellular superoxide dismutase (SOD3) gene transfer. SOD3 was shown to reduce oxidative stress, to normalize glucose metabolism, and to enhance cell proliferation in the ischemic muscle. Analysis of the mitogenic Ras-Erk1/2 pathway showed SOD3 mediated induction offering a plausible explanation for enhanced cell proliferation. In addition, SOD3 reduced NF-κB activity by enhancing IκBα expression thus leading to reduced expression of inflammatory cytokines and adhesion molecules with consequent reduction in macrophage infiltration. Secondly, we sought to determine the fate and the effect of locally transplanted mesenchymal stem/stromal cells (MSCs) in acute ischemia. We showed that a vast majority of the transplanted cells are cleared from the injury site within 24 hours after local transplantation. Despite rapid clearance, transplantation was able to temporarily promote angiogenesis and cell proliferation in the muscle. Lack of graft-derived growth factor expression suggests other than secretory function to mediate this observed effect. In conclusion, both SOD3 and MSCs could be utilized to alleviate peripheral ischemia induced tissue injury. We have described a previously unidentified growth regulatory role for SOD3, and suggest a novel mechanism whereby transplanted MSCs enhance the reparative potential of the recipient tissue through physical contacts.

On Undecidable Dynamical Properties of Reversible One-Dimensional Cellular Automata

Cellular automata are models for massively parallel computation. A cellular automaton consists of cells which are arranged in some kind of regular lattice and a local update rule which updates the state of each cell according to the states of the cell's neighbors on each step of the computation. This work focuses on reversible one-dimensional cellular automata in which the cells are arranged in a two-way in_nite line and the computation is reversible, that is, the previous states of the cells can be derived from the current ones. In this work it is shown that several properties of reversible one-dimensional cellular automata are algorithmically undecidable, that is, there exists no algorithm that would tell whether a given cellular automaton has the property or not. It is shown that the tiling problem of Wang tiles remains undecidable even in some very restricted special cases. It follows that it is undecidable whether some given states will always appear in computations by the given cellular automaton. It also follows that a weaker form of expansivity, which is a concept of dynamical systems, is an undecidable property for reversible one-dimensional cellular automata. It is shown that several properties of dynamical systems are undecidable for reversible one-dimensional cellular automata. It shown that sensitivity to initial conditions and topological mixing are undecidable properties. Furthermore, non-sensitive and mixing cellular automata are recursively inseparable. It follows that also chaotic behavior is an undecidable property for reversible one-dimensional cellular automata.

The physico-chemical properties of 2-methoxyphenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II)

The complexes of 2-methoxyhenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II)with the general formula: M(C9H9O4)3·4H2O, where M(II) = Mn, Co, Ni and Cu have been synthesized and characterized by elemental analysis, IR spectroscopy, magnetic and thermogravimetric studies and also X-ray diffraction measurements. The complexes have colours typical for M(II) ions (Mn(II) - a pale pink, Co(II) - pink, Ni(II) - green, and Cu(II) - blue). The carboxylate group binds as monodentate and bidentate ligands. On heating to 1273K in air the complexes decompose in the same way. At first, they dehydrate in one step to anhydrous salts, that next decompose to the oxides of respective metals with the intermediate formation of the oxycarbonates. Their solubility in water at 293K is of the order of 10-5 mol·dm-3. The magnetic moments of analysed complexes were determined in the range of 76-303K. The results reveal them to be high-spin complexes of weak ligand fields.

Magnetic and transport properties of LaMnO3+δ, La1-xCaxMnO3, La1-xCaxMn1-yFeyO3 and La1-xSrxMn1-yFeyO3

Interest to hole-doped mixed-valence manganite perovskites is connected to the ‘colossal’ magnetoresistance. This effect or huge drop of the resistivity, ρ, in external magnetic field, B, attains usually the maximum value near the ferromagnetic Curie temperature, TC. In this thesis are investigated conductivity mechanisms and magnetic properties of the manganite perovskite compounds LaMnO3+, La1-xCaxMnO3, La1-xCaxMn1-yFeyO3 and La1- xSrxMn1-yFeyO3. When the present work was started the key role of the phase separation and its influence on the properties of the colossal magnetoresistive materials were not clear. Our main results are based on temperature dependencies of the magnetoresistance and magnetothermopower, investigated in the temperature interval of 4.2 - 300 K in magnetic fields up to 10 T. The magnetization was studied in the same temperature range in weak (up to 0.1 T) magnetic fields. LaMnO3+δ is the parent compound for preparation of the hole-doped CMR materials. The dependences of such parameters as the Curie temperature, TC, the Coulomb gap, Δ, the rigid gap, γ, and the localization radius, a, on pressure, p, are observed in LaMnO3+δ. It has been established that the dependences above can be interpreted by increase of the electron bandwidth and decrease of the polaron potential well when p is increased. Generally, pressure stimulates delocalization of the electrons in LaMnO3+δ. Doping of LaMnO3 with Ca, leading to La1-xCaxMnO3, changes the Mn3+/Mn4+ ratio significantly and brings an additional disorder to the crystal lattice. Phase separation in a form of mixture of the ferromagnetic and the spin glass phases was observed and investigated in La1- xCaxMnO3 at x between 0 and 0.4. Influence of the replacement of Mn by Fe is studied in La0.7Ca0.3Mn1−yFeyO3 and La0.7Sr0.3Mn1−yFeyO3. Asymmetry of the soft Coulomb gap and of the rigid gap in the density of localized states, small shift of the centre of the gaps with respect to the Fermi level and cubic asymmetry of the density of states are obtained in La0.7Ca0.3Mn1−yFeyO3. Damping of TC with y is connected to breaking of the double-exchange interaction by doping with Fe, whereas the irreversibility and the critical behavior of the magnetic susceptibility are determined by the phase separation and the frustrated magnetic state of La0.7Sr0.3Mn1−yFeyO3.

Effect of pulps fractionation on formation and strength properties of laboratory hand sheets

The objectives of the work were to study the effect of dewatering time varying on formation properties of papersheets, to determine the role of fines fraction in creation of paper with good formation and strength properties of papersheets, and also to study the effect of charge modification of fibers fractionations on formation properties of handsheets. The paper formation is one of the most important structural properties of paper. This property has effect on physical and optical characteristics of paper. In thi work the effect of formation on tensile strength was determined. The formation properties were analyzed by using the AMBERTEC Beta Formation Tester. The PAM addition as a f;locculant agent did some changes in the formation of paper. Paper sheets were also made from different furnishes of both birch and pine pulps. The fibers particles as a fines have great effect on drainability changes. Fines fraction played important role in papermaking. The two kinds of pulps (pine and birch pulps) were also used in this work for investigation of fines role. As it was expected the fines fraction gave positive effect on paper formation, but when fines fraction was added above initial fines content the formation of paper was deteriorated. The effect of paper formation on tensile strength was also determined. In many cases the poor formation of paper had negative effect on strength properties of paper..

Influence of topography and surface chemistry on the wetting properties of TiO2-based ceramic coatings

Vätning av fasta ytor är ett viktigt fenomen i såväl naturen som i en lång rad av industriella tillämpningar. Det är allmänt känt att vätningen av en fast yta styrs av ytans kemi samt struktur. Målsättningen med avhandlingen var att studera hur kemisk heterogenitet och ytråhet på nanometernivå påverkar vätningsegenskaperna hos en fast yta. Ytorna som studerades var titandioxid-baserade kerama ytor som framställdes med hjälp av en sol-gel process. Vätningstudierna utfördes genom kontaktvinkelmätningar, vilket innebär att man mäter vinkeln som vätska/luft-gränsskiktet hos en vätskedroppe bildar mot en fast yta. Ytråheten hos materialen studerades främst genom atomkraftsmikroskopi (AFM). I AFM detekteras ytans struktur av en mycket skarp nål som skannar ytan. Resultaten i avhandlingen kunde framgångsrikt modelleras med existerande teorier för vätning av heterogena ytor.

Influence of Heat Treatment on Strength Properties of Finger-jointed Components

The purpose for the thesis was to study the thermo treatment of finger-jointed wood. The thesis concentrated on examining the tensile and bending strength of finger-jointed and thermo treated wood. The aim was to find out how different treatment temperature levels and adhesives influence the strength of wood that has been finger-jointed before heat treatment. Secondary objectives were to examine the influence of the treatment time at one temperature, determine differences in the strength between the joints in heartwood and sapwood, examine the visual appearance of the finger joints after the treatment and establish possibilities to reach a characteristic strength level corresponding to C14. Only minor differences in strength properties were measured between the finger-jointed wood treatments II and III. A greater difference was shown between these two treatment temperatures I, which lead to reduced strength. The average strength of joints glued with adhesive 2 was higher after treatments II and III compared to those glued with the adhesive 1. At the treatment temperature I, the adhesive 1 strength properties were at the same level compared to the adhesive 2 or better. There were not any significant differences.

Dynamical and structural properties of dendrimer macromolecules

This work is devoted to the study of the dynamical and structural properties of dendrimers. Different approaches were used: analytical theory, computer simulation results and experimental NMR studies. The theory of the relaxation spectrum of dendrimer macromolecules was developed. Relaxation processes which are manifest in the local orientational mobility of dendrimer macromolecules were established and studied in detail. Theoretical results and conclusions were used for experimental studies of carbosilane dendimers.