994 resultados para Almost Complex Manifold
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Rare earth (RE) ions have spectroscopic characteristics to emit light in narrow lines, which makes RE complexes with organic ligands candidates for full color OLED (Organic Light Emitting Diode) applications. In particular, beta-diketone rare earth (RE(3+)) complexes show high fluorescence emission efficiency due to the high absorption coefficient of the beta-diketone and energy transfer to the central ion. In this work, the fabrication and the electroluminescent properties of devices containing a double and triple-layer OLED using a new beta-diketone complex, [Eu(bmdm)(3)(tppo)(2)], as transporting and emitting layers are compared and discussed. The double and triple-layer devices based on this complex present the following configurations respectively: device 1: ITO/TPD (40 nm)/[Eu(bmdm)(3)(tppo)(2)] (40 nm)/Al (150 nm); device 2: ITO/TPD (40 nm)/[Eu(bmdm)(3) (tppo)(2)] (40 nm)/Alq(3) (20 nm)/Al (150 nm) and device 3: ITO/TPD (40 nm)/bmdm-ligand (40 nm)/Al (150 nm), were TPD is (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1-biphenil-4,4-diamine) and bmdm is butyl methoxy-dibenzoyl-methane. All the films were deposited by thermal evaporation carried out in a high vacuum system. These devices exhibit high intensity photo- (PL) and electro-luminescent (EL) emission. Electroluminescence spectra show emission from Eu(3+) ions attributed to the (5)D(0) to (7)F(J) (J = 0, 1, 2, 3 and 4) transitions with the hypersensitive (5)D(o) -> (7)F(2) transition (around 612 nm) as the most prominent one. Moreover, a transition from (5)D(1) to (7)F(1) is also observed around 538 nm. The OLED light emission was almost linear with the current density. The EL CIE chromaticity coordinates (X = 0.66 and Y = 0.33) show the dominant wavelength, lambda(d) = 609 nm, and the color gamut achieved by this device is 0.99 in the CIE color space. (c) 2006 Elsevier B.V. All rights reserved.
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Meiotic cells of triploid male rainbow trouts were analyzed by a surface-spreading SC technique in order to show the process of chromosome synapsis. At zygotene the formation of SCs involved, almost exclusively, two sets of lateral elements (LEs), and the remaining set of LEs presented different synaptic configurations involving one, two, three, or four LEs. The absence of SCs involving more than two LEs from mid- to late pachytene indicates that the multivalents produced by synapsis involving more than two LEs, are eliminated before the end of pachytene; thus, the mechanism of chromosome pairing in triploid male rainbow trouts produces, almost exclusively, bivalents with a probable extensive nonhomologous synapsis involving the extra set of chromosomes.
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Let M2n+1 be a C(CPn) -singular manifold. We study functions and vector fields with isolated singularities on M2n+1. A C(CPn) -singular manifold is obtained from a smooth manifold M2n+1 with boundary in the form of a disjoint union of complex projective spaces CPn boolean OR CPn boolean OR ... boolean OR CPn with subsequent capture of a cone over each component of the boundary. Let M2n+1 be a compact C(CPn) -singular manifold with k singular points. The Euler characteristic of M2n+1 is equal to chi(M2n+1) = k(1 - n)/2. Let M2n+1 be a C(CPn)-singular manifold with singular points m(1), ..., m(k). Suppose that, on M2n+1, there exists an almost smooth vector field V (x) with finite number of zeros m(1), ..., m(k), x(1), ..., x(1). Then chi(M2n+1) = Sigma(l)(i=1) ind(x(i)) + Sigma(k)(i=1) ind(m(i)).
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The dehydration, thermal decomposition and transition phase stage of Zn(II)-diclofenac compoundwere studied by simultaneous TG-DTA and DSC techniques. The TG and DSC curves of this compoundwere obtained with the mass of sample of 2 and 5 mg. Additionally, DSC curves were carried out inopened and closed a-alumina pans under static and nitrogen atmosphere. The DTA and DSC curves showthat this compound possesses exothermic transition phase between 170-180 ºC, which it is irreversible(monotropic reaction). The kinetics study of this transition phase stage was evaluated by DSC undernon-isothermal conditions. The obtained data were evaluated with the isoconversional method, where thevalues of activation energy (Ea/kJmol-1) was plotted in function of the conversion degree (a). The resultsshow that due to mass sample, different activation energies were obtained. From these curves a tendencycan be seen where the plots maintain the same profile for closed lids and almost run parallel to each other.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Nitrosyl ruthenium complexes are promising NO donor agents with numerous advantages for the biologic applications of NO. We have characterized the NO release from the nitrosyl ruthenium complex [Ru(NO2)(bpy)(2)(4-pic)](+) (I) and the reactive oxygen/nitrogen species (ROS/RNS)-mediated NO actions on isolated rat liver mitochondria. The results indicated that oxidation of mitochondrial NADH promotes NO release from (I) in a manner mediated by NO2 formation (at neutral pH) as in mammalian cells, followed by an oxygen atom transfer mechanism (OAT). The NO released from (I) uncoupled mitochondria at low concentrations/incubation times and inhibited the respiratory chain at high concentrations/incubation times. In the presence of ROS generated by mitochondria NO gave rise to peroxynitrite, which, in turn, inhibited the respiratory chain and oxidized membrane protein-thiols to elicit a Ca2+-independent mitochondrial permeability transition; this process was only partially inhibited by cyclosporine-A, almost fully inhibited by the thiol reagent N-ethylmaleimide (NEM) and fully inhibited by the NO scavenger 2-(4-carboxyphenyl)-4,45,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). These actions correlated with the release of cytochrome c from isolated mitochondria as detected by Western blotting analysis. These events, typically involved in cell necrosis and/or apoptosis denote a potential specific action of (I) and analogs against tumor cells via mitochondria-mediated processes. (C) 2012 Elsevier Inc. All rights reserved.
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This thesis deals with physical factors and biological interactions affecting the distribution of two fucoid species, Fucus vesiculosus and F. serratus, in the Baltic Sea. Studies have been carried out in two quite different environments: an archipelago, and an open rocky coast. The archipelago has an extremely long coastline with a heterogeneous submerged landscape of different substrate types, slopes, water qualities, and degrees of wave exposure. The factors influencing F. vesiculosus distribution, morphology and epiphyte composition were studied in the Stockholm archipelago using field surveys and spatial modelling in Geographic information systems (GIS). A GIS-method to estimate wave exposure was developed and validated by comparing the result to an index based on vertical zonation of lichens. Wave exposure was considered an important factor for predicting the distribution of F. vesiculosus by its ability to clean hard surfaces from silt, and a predictive model was constructed based on the information of wave exposure and slope of the shore. It is suggested that the lower distribution boundary of attached F. vesiculosus is set by sediment in sheltered parts of the archipelago, and by light availability in highly wave exposed parts. The morphology of F. vesiculosus was studied over a wave exposure gradient, and several characters responded in accordance with earlier studies. However, when separating effects of wave exposure from effects of other confounding water property parameters, only thallus width was significantly different. Several water property parameters were shown to be correlated with wave exposure in the Stockholm archipelago, and the mechanism responsible for the effects on F. vesiculosus morphology is discussed. The composition of epiphytes on F. vesiculosus varied over a wave exposure gradient with a positive correlation to Elachista fucicola, and a negative to Chorda filum. At an open coast the physical environment is much less heterogeneous compared to an archipelago. The distributions of F. vesiculosus, F. serratus, turf-forming algae, and the seafloor substrate, were surveyed along the open coasts of Öland and Gotland. Turf-forming algae dominated all hard substrates in the area, and Polysiphonia fucoides was most abundant. At the Gotland coast F. vesiculosus was less abundant than at the Öland coast, and F. serratus occurred only in the southern-most part. Fucus serratus was increasingly more common towards south which was interpreted as an effect mainly of the Baltic salinity gradient, or the variation of salinity that has occurred in the past. The effects of turf-forming algae and sediment on F. serratus recruitment at 7 m depth off the Öland east coast were studied in the field, and by laboratory experiments. Almost no recruits were found in the algal turf outside the F. serratus patches. More fine sediment was found in the turf than in the F. serratus patches, suggesting that the turf accumulates sediment by decreasing resuspension. Both filamentous algae and sediment decreased the attachment ability of F. serratus zygotes and survival of recruits, and sediment had the strongest effect. It is therefore suggested that F. serratus has difficulties recruiting outside its patches, and that these difficulties are enforced by the eutrophication of the Baltic Sea, which has favoured growth of filamentous algae and increased sedimentation. An overall conclusion is that Fucus distribution is affected by large-scale-factors, such as the eutrophication and salinity changes of the Baltic Sea, as well as by small-scale variation in wave exposure, substrate and slope, and by surface competition with neighbouring species.
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Wir berechnen die Eulerzahl der 10-dimensionalen exzeptionellen irreduziblen symplektischen Mannigfaltigkeit, die von O Grady konstruiert wurde. Die Idee besteht darin, zunächst eine Lagrangefaserung zu konstruieren und dann die Eulerzahlen der Fasern zu berechnen. Es stellt sich heraus, dass fast alle Fasern die Eulerzahl 0 haben, und deswegen reduziert sich das Problem auf die Berechnung der Eulerzahlen der übrigen Fasern. Diese Fasern sind Modulräume von halbstabilen Garben auf singulären Kurven. Der Hauptteil dieser Dissertation ist der Berechnung der Eulerzahlen dieser Modulräume gewidmet. Diese Resultate sind von unabhängigem Interesse.
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A thorough investigation was made of the structure-property relation of well-defined statistical, gradient and block copolymers of various compositions. Among the copolymers studied were those which were synthesized using isobornyl acrylate (IBA) and n-butyl acrylate (nBA) monomer units. The copolymers exhibited several unique properties that make them suitable materials for a range of applications. The thermomechanical properties of these new materials were compared to acrylate homopolymers. By the proper choice of the IBA/nBA monomer ratio, it was possible to tune the glass transition temperature of the statistical P(IBA-co-nBA) copolymers. The measured Tg’s of the copolymers with different IBA/nBA monomer ratios followed a trend that fitted well with the Fox equation prediction. While statistical copolymers showed a single glass transition (Tg between -50 and 90 ºC depending on composition), DSC block copolymers showed two Tg’s and the gradient copolymer showed a single, but very broad, glass transition. PMBL-PBA-PMBL triblock copolymers of different composition ratios were also studied and revealed a microphase separated morphology of mostly cylindrical PMBL domains hexagonally arranged in the PBA matrix. DMA studies confirmed the phase separated morphology of the copolymers. Tensile studies showed the linear PMBL-PBA-PMBL triblock copolymers having a relatively low elongation at break that was increased by replacing the PMBL hard blocks with the less brittle random PMBL-r-PMMA blocks. The 10- and 20-arm PBA-PMBL copolymers which were studied revealed even more unique properties. SAXS results showed a mixture of cylindrical PMBL domains hexagonally arranged in the PBA matrix, as well as lamellar. Despite PMBL’s brittleness, the triblock and multi-arm PBA-PMBL copolymers could become suitable materials for high temperature applications due to PMBL’s high glass transition temperature and high thermal stability. The structure-property relation of multi-arm star PBA-PMMA block copolymers was also investigated. Small-angle X-ray scattering revealed a phase separated morphology of cylindrical PMMA domains hexagonally arranged in the PBA matrix. DMA studies found that these materials possess typical elastomeric behavior in a broad range of service temperatures up to at least 250°C. The ultimate tensile strength and the elastic modulus of the 10- and 20-arm star PBA-PMMA block copolymers are significantly higher than those of their 3-arm or linear ABA type counterparts with similar composition, indicating a strong effect of the number of arms on the tensile properties. Siloxane-based copolymers were also studied and one of the main objectives here was to examine the possibility to synthesize trifluoropropyl-containing siloxane copolymers of gradient distribution of trifluoropropyl groups along the chain. DMA results of the PDMS-PMTFPS siloxane copolymers synthesized via simultaneous copolymerization showed that due to the large difference in reactivity rates of 2,4,6-tris(3,3,3-trifluoropropyl)-2,4,6-trimethylcyclotrisiloxane (F) and hexamethylcyclotrisiloxane (D), a copolymer of almost block structure containing only a narrow intermediate fragment with gradient distribution of the component units was obtained. A more dispersed distribution of the trifluoropropyl groups was obtained by the semi-batch copolymerization process, as the DMA results revealed more ‘‘pure gradient type’’ features for the siloxane copolymers which were synthesized by adding F at a controlled rate to the polymerization of the less reactive D. As with trifluoropropyl-containing siloxane copolymers, vinyl-containing polysiloxanes may be converted to a variety of useful polysiloxane materials by chemical modification. But much like the trifluoropropyl-containing siloxane copolymers, as a result of so much difference in the reactivities between the component units 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane (V) and hexamethylcyclotrisiloxane (D), thermal and mechanical properties of the PDMS-PMVS copolymers obtained by simultaneous copolymerization was similar to those of block copolymers. Only the copolymers obtained by semi-batch method showed properties typical for gradient copolymers.
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The 3 angstrom resolution crystal structure of the Escherichia coli catabolite gene activator protein (CAP) complexed with a 30-base pair DNA sequence shows that the DNA is bent by 900. This bend results almost entirely from two 400 kinks that occur between TG/CA base pairs at positions 5 and 6 on each side of the dyad axis of the complex. DNA sequence discrimination by CAP derives both from sequence-dependent distortion of the DNA helix and from direct hydrogen-bonding interactions between three protein side chains and the exposed edges of three base pairs in the major groove of the DNA. The structure of this transcription factor-DNA complex provides insights into possible mechanisms of transcription activation
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In the crystal structure of the title compound (systematic name: 2,3-dichlorobenzene-1,4-diol 2,3-dichlorocyclohexa-2,5-diene-1,4-dione monohydrate), C(6)H(4)Cl(2)O(2)center dot C(6)H(2)Cl(2)O(2)center dot H(2)O, the 2,3-dichloro-1,4-hydroquinone donor (D) and the 2,3-dichloro-1,4-benzoquinone acceptor (A) molecules form alternating stacks along [100]. Their molecular planes [maximum deviations for non-H atoms: 0.0133 (14) (D) and 0.0763 (14) angstrom (A)] are inclined to one another by 1.45 (3)degrees and are thus almost parallel. There are pi-pi interactions involving the D and A molecules, with centroid-centroid distances of 3.5043 (9) and 3.9548 (9) angstrom. Intermolecular O-H center dot center dot center dot O hydrogen bonds involving the water molecule and the hydroxy and ketone groups lead to the formation of two-dimensional networks lying parallel to (001). These networks are linked by C-H center dot center dot center dot O interactions, forming a three-dimensional structure.
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Rotational atherectomy has been regaining interest over the last couple of years after it almost has disappeared from most interventional catheterization laboratories for several years due to failure to prove its original concept of improving long term results of percutaneous coronary interventions (PCI) as was repeatedly shown in studies in the 1990s. Its revival coupled the introduction of drug-eluting stents (DES); these devices have led to treating much more complex lesions and high-risk patients by PCI. However, real-world experience suggested that off-label use of DES is associated with a higher rate of early and late stent thrombosis. Therefore, more attention is now being paid to the initial implantation technique of DES including aggressive lesion preparation to facilitate stent delivery and expansion. The limited studies with rot-ablation and DES showed promising results with no long term safety concerns. In these studies, a subtle observation was made suggesting that rot-ablation prior to DES implantation in such lesions may have an add-on effect on long term outcome compared to DES alone. An ongoing multicenter study is investigating such effect among complex calcified coronary lesions. Even if this additive benefit does not prove true, rot-ablation remains an efficient tool for preparing certain lesions to facilitate effective and safe DES implantation. Therefore, interventional training programs should focus on this difficult technique to bridge the gap of experience which resulted from neglecting it for several years. In this regard, dedicated courses at experienced sites as well as medical simulation may be appropriate.
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Measuring shallow seismic sources provides a way to reveal processes that cannot be directly observed, but the correct interpretation and value of these signals depend on the ability to distinguish source from propagation effects. Furthermore, seismic signals produced by a resonating source can look almost identical to those produced by impulsive sources, but modified along the path. Distinguishing these two phenomena can be accomplished by examining the wavefield with small aperture arrays or by recording seismicity near to the source when possible. We examine source and path effects in two different environments: Bering Glacier, Alaska and Villarrica Volcano, Chile. Using three 3-element seismic arrays near the terminus of the Bering Glacier, we have identified and located both terminus calving and iceberg breakup events. We show that automated array analysis provided a robust way to locate icequake events using P waves. This analysis also showed that arrivals within the long-period codas were incoherent within the small aperture arrays, demonstrating that these codas previously attributed to crack resonance were in fact a result of a complicated path rather than a source effect. At Villarrica Volcano, seismometers deployed from near the vent to ~10 km revealed that a several cycle long-period source signal recorded at the vent appeared elongated in the far-field. We used data collected from the stations nearest to the vent to invert for the repetitive seismic source, and found it corresponded to a shallow force within the lava lake oriented N75°E and dipping 7° from horizontal. We also used this repetitive signal to search the data for additional seismic and infrasonic properties which included calculating seismic-acoustic delay times, volcano acoustic-seismic ratios and energies, event frequency, and real-time seismic amplitude measurements. These calculations revealed lava lake level and activity fluctuations consistent with lava lake level changes inferred from the persistent infrasonic tremor.
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Tuberous sclerosis complex (TSC) is a multisystem, autosomal dominant disorder affecting approximately 1 in 6000 births. Developmental brain abnormalities cause substantial morbidity and mortality and often lead to neurological disease including epilepsy, cognitive disabilities, and autism. TSC is caused by inactivating mutations in either TSC1 or TSC2, whose protein products are known inhibitors of mTORC1, an important kinase regulating translation and cell growth. Nonetheless, neither the pathophysiology of the neurological manifestations of TSC nor the extent of mTORC1 involvement in the development of these lesions is known. Murine models would greatly advance the study of this debilitating disorder. This thesis will describe the generation and characterization of a novel brain-specific mouse model of TSC, Tsc2flox/ko;hGFAP-Cre. In this model, the Tsc2 gene has been removed from most neurons and glia of the cortex and hippocampus by targeted Cre-mediated deletion in radial glial neuroprogenitor cells. The Tsc2flox/ko;hGFAP-Cre mice fail to thrive beginning postnatal day 8 and die from seizures around 23 days. Further characterization of these mice demonstrated megalencephaly, enlarged neurons, abnormal neuronal migration, altered progenitor pools, hypomyelination, and an astrogliosis. The similarity of these defects to those of TSC patients establishes this mouse as an excellent model for the study of the neuropathology of TSC and testing novel therapies. We further describe the use of this mouse model to assess the therapeutic potential of the macrolide rapamycin, an inhibitor of mTORC1. We demonstrate that rapamycin administered from postnatal day 10 can extend the life of the mutant animals 5 fold. Since TSC is a neurodevelopmental disorder, we also assessed in utero and/or immediate postnatal treatment of the animals with rapamycin. Amazingly, combined in utero and postnatal rapamycin effected a histologic rescue that was almost indistinguishable from control animals, indicating that dysregulation of mTORC1 plays a large role in TSC neuropathology. In spite of the almost complete histologic rescue, behavioral studies demonstrated that combined treatment resulted in poorer learning and memory than postnatal treatment alone. Postnatally-treated animals behaved similarly to treated controls, suggesting that immediate human treatment in the newborn period might provide the most opportune developmental timepoint for rapamycin administration.
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The VirB11 ATPase is an essential component of an Agrobacterium tumefaciens type IV bacterial secretion system that transfers oncogenic nucleoprotein complexes to susceptible plant cells. This dissertation investigates the subcellular localization and homo-oligomeric state of the VirB11 ATPase in order to provide insights about the assembly of the protein as a subunit of this membrane-associated transfer system. Subcellular fractionation studies and quantitative immunoblot analysis demonstrated that $\sim$30% of VirB11 partitioned as soluble protein and $\sim$70% was tightly associated with the bacterial cytoplasmic membrane. No differences were detected in VirB11 subcellular localization and membrane association in the presence or absence of other transport system components. Mutations in virB11 affecting protein function were mapped near the amino terminus, just upstream of a region encoding a Walker 'A' nucleotide-binding site, and within the Walker 'A' motif partitioned almost exclusively with the cytoplasmic membrane, suggesting that an activity associated with nucleotide binding could modulate the affinity of VirB11 for the cytoplasmic membrane. Merodiploid analysis of VirB11 mutant and truncation derivatives provided strong evidence that VirB11 functions as a homo- or heteromultimer and that the C-terminal half of VirB11 contains a protein interaction domain. A combination of biochemical and molecular genetic approaches suggested that VirB11 and the green fluorescence protein (GFP) formed a mixed multimer as demonstrated by immunoprecipitation experiments with anti-GFP antibodies. Second, a hybrid protein composed of VirB11 fused to the N-terminal DNA-binding domain of bacteriophage $\lambda$ cI repressor conferred immunity to $\lambda$ superinfection, demonstrating that VirB11 self-association promotes dimerization of the chimeric repressor. A conserved Walker 'A' motif, though required for VirB11 function in T-complex export, was not necessary for VirB11 self-association. Sequences in both the N- and the C-terminal halves of the protein were found to contribute to self-association of the full length protein. Chemical cross-linking experiments with His$\sb6$ tagged VirB11 suggested that VirB11 probably assembles into a higher order homo-oligomeric complex. ^