Blue-green and red photoluminescence in CaTiO3 : Sm

Blue-green and red photoluminescence (PL) emission in structurally disordered CaTiO3:Sm (CT:Sm) powders was observed at room temperature with laser excitation at 350.7 nm. The perovskite-like titanate CT:Sm powders prepared by a soft chemical processing at different temperatures of annealing were structurally characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES). The results indicate that the generation of the broad PL band is related to order-disorder degree in the perovskitelike structure. (c) 2006 Elsevier B.V. All rights reserved.

Disorder-dependent photoluminescence in Ba0.8Ca0.2TiO3 at room temperature

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bioprospecção e caracterização químico-funcional de compostos orgânicos da baixas massas molecularesde venenos das vespas sociais: Agelaia pallipes pallipes, Agelaia vicina e Polybia paulista (Hymenoptera - Vespidae)

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

LaNiO3 nanotubes produced using a template-assisted method

We have studied the experimental conditions needed to produce LaNiO3 (LNO) nanostructures using a template-assisted method. In this route, a mesoporous anodic aluminum oxide template was filled with a chemical solution that had been prepared with polymeric precursors route. The precursor solutions and synthesized samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis, infrared spectroscopy and high-resolution scanning electron microscopy (HRSEM). The XRD results for the samples that were heat-treated at 700 degrees C revealed that these samples crystallize in a perovskite-like LaNiO3 structure. HRSEM images revealed that the samples prepared with different deposition times (0.5, 1 and 2 h) promoted the formation of LaNiO3 nanotubes with different wall thicknesses.

On the substrate- and stereospecificity of the plant carotenoid cleavage dioxygenase 7

Strigolactones are phytohormones synthesized from carotenoids via a stereospecific pathway involving the carotenoid cleavage dioxygenases 7 (CCD7) and 8. CCD7 cleaves 9-cis-β-carotene to form a supposedly 9-cis-configured β-apo-10′-carotenal. CCD8 converts this intermediate through a combination of yet undetermined reactions into the strigolactone-like compound carlactone. Here, we investigated the substrate and stereo-specificity of the Arabidopsis and pea CCD7 and determined the stereo-configuration of the β-apo-10′-carotenal intermediate by using Nuclear Magnetic Resonance Spectroscopy. Our data unequivocally demonstrate the 9-cis-configuration of the intermediate. Both CCD7s cleave different 9-cis-carotenoids, yielding hydroxylated 9-cis-apo-10′-carotenals that may lead to hydroxylated carlactones, but show highest affinity for 9-cis-β-carotene.

Um dermatam sulfato antitrombótico do camarão Litopenaeus vanammei inibe a inflamação e angiogênese

Inflammation is combined of a vascular and a cellular reaction, resulting in different cells and tissue responses, both the intravascular and extravascular environment. As the inflammatory process occurs, coagulation proteases, in particular thrombin (FIIa), are able to initiate various cellular responses in vascular biology and therefore is often observed activation of other biological systems, leading to complications during an event inflammatory, such as thrombosis and angiogenesis. Thus, antagonists molecules of these events are interesting models for the development of novel anti-inflammatory drugs. Thereby, it is worth stressing the glycosaminoglycans (GAGs), which are able to interact with several proteins involved in important biological processes, including inflammation and coagulation. Therefore, this study aimed to evaluate the anti-inflammatory, antithrombotic and anti-angiogenic potentials, as well anticoagulant of a dermatan sulfate-like GAG (DS) extracted from the Litopenaeus vannamei cephalotorax. The compound was obtained after proteolysis and purification by ion-exchange chromatography. After total digestion by DS-like compounds digesting lyases (chondroitinase ABC), the DS-like nature was revealed, and then called DSL. The shrimp compound showed reduced anticoagulant effect by the aPTT assay, but high anti-IIa activity, directly and through heparin cofactor II. On inflammation, the compound had a significant inhibitory effect with the reduction of proinflammatory cytokines. Potential Inhibitory were reported in the antithrombotic and anti-angiogenic assay, the latter being dose dependent. As for anti-hemostatic activity, the polysaccharides did not induced significant bleeding effect. Thus, the results shown by the shrimp DS-like compound indicate this glycosaminoglycan as a biotechnology target with prospects for the development of new multipotent drugs.

Functional alkali tantalate 2D structures for microelectronics and related applications

Alkali tantalates and niobates, including K(Ta / Nb)O3, Li(Ta / Nb)O3 and Na(Ta / Nb)O3, are a very promising ferroic family of lead-free compounds with perovskite-like structures. Their versatile properties make them potentially interesting for current and future application in microelectronics, photocatalysis, energy and biomedics. Among them potassium tantalate, KTaO3 (KTO), has been raising interest as an alternative for the well-known strontium titanate, SrTiO3 (STO). KTO is a perovskite oxide with a quantum paraelectric behaviour when electrically stimulated and a highly polarizable lattice, giving opportunity to tailor its properties via external or internal stimuli. However problems related with the fabrication of either bulk or 2D nanostructures makes KTO not yet a viable alternative to STO. Within this context and to contribute scientifically to the leverage tantalate based compounds applications, the main goals of this thesis are: i) to produce and characterise thin films of alkali tantalates by chemical solution deposition on rigid Si based substrates, at reduced temperatures to be compatible with Si technology, ii) to fulfil scientific knowledge gaps in these relevant functional materials related to their energetics and ii) to exploit alternative applications for alkali tantalates, as photocatalysis. In what concerns the synthesis attention was given to the understanding of the phase formation in potassium tantalate synthesized via distinct routes, to control the crystallization of desired perovskite structure and to avoid low temperature pyrochlore or K-deficient phases. The phase formation process in alkali tantalates is far from being deeply analysed, as in the case of Pb-containing perovskites, therefore the work was initially focused on the process-phase relationship to identify the driving forces responsible to regulate the synthesis. Comparison of phase formation paths in conventional solid-state reaction and sol-gel method was conducted. The structural analyses revealed that intermediate pyrochlore K2Ta2O6 structure is not formed at any stage of the reaction using conventional solid-state reaction. On the other hand in the solution based processes, as alkoxide-based route, the crystallization of the perovskite occurs through the intermediate pyrochlore phase; at low temperatures pyrochlore is dominant and it is transformed to perovskite at >800 °C. The kinetic analysis carried out by using Johnson-MehlAvrami-Kolmogorow model and quantitative X-ray diffraction (XRD) demonstrated that in sol-gel derived powders the crystallization occurs in two stages: i) at early stage of the reaction dominated by primary nucleation, the mechanism is phase-boundary controlled, and ii) at the second stage the low value of Avrami exponent, n ~ 0.3, does not follow any reported category, thus not permitting an easy identification of the mechanism. Then, in collaboration with Prof. Alexandra Navrotsky group from the University of California at Davis (USA), thermodynamic studies were conducted, using high temperature oxide melt solution calorimetry. The enthalpies of formation of three structures: pyrochlore, perovskite and tetragonal tungsten bronze K6Ta10.8O30 (TTB) were calculated. The enthalpies of formation from corresponding oxides, ∆Hfox, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -203.63 ± 2.84 kJ/mol, - 358.02 ± 3.74 kJ/mol, and -1252.34 ± 10.10 kJ/mol, respectively, whereas from elements, ∆Hfel, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -1408.96 ± 3.73 kJ/mol, -2790.82 ± 6.06 kJ/mol, and -13393.04 ± 31.15 kJ/mol, respectively. The possible decomposition reactions of K-deficient KTa2.2O6 pyrochlore to KTaO3 perovskite and Ta2O5 (reaction 1) or to TTB K6Ta10.8O30 and Ta2O5 (reaction 2) were proposed, and the enthalpies were calculated to be 308.79 ± 4.41 kJ/mol and 895.79 ± 8.64 kJ/mol for reaction 1 and reaction 2, respectively. The reactions are strongly endothermic, indicating that these decompositions are energetically unfavourable, since it is unlikely that any entropy term could override such a large positive enthalpy. The energetic studies prove that pyrochlore is energetically more stable phase than perovskite at low temperature. Thus, the local order of the amorphous precipitates drives the crystallization into the most favourable structure that is the pyrochlore one with similar local organization; the distance between nearest neighbours in the amorphous or short-range ordered phase is very close to that in pyrochlore. Taking into account the stoichiometric deviation in KTO system, the selection of the most appropriate fabrication / deposition technique in thin films technology is a key issue, especially concerning complex ferroelectric oxides. Chemical solution deposition has been widely reported as a processing method to growth KTO thin films, but classical alkoxide route allows to crystallize perovskite phase at temperatures >800 °C, while the temperature endurance of platinized Si wafers is ~700 °C. Therefore, alternative diol-based routes, with distinct potassium carboxylate precursors, was developed aiming to stabilize the precursor solution, to avoid using toxic solvents and to decrease the crystallization temperature of the perovskite phase. Studies on powders revealed that in the case of KTOac (solution based on potassium acetate), a mixture of perovskite and pyrochlore phases is detected at temperature as low as 450 °C, and gradual transformation into monophasic perovskite structure occurs as temperature increases up to 750 °C, however the desired monophasic KTaO3 perovskite phase is not achieved. In the case of KTOacac (solution with potassium acetylacetonate), a broad peak is detected at temperatures <650 °C, characteristic of amorphous structures, while at higher temperatures diffraction lines from pyrochlore and perovskite phases are visible and a monophasic perovskite KTaO3 is formed at >700 °C. Infrared analysis indicated that the differences are due to a strong deformation of the carbonate-based structures upon heating. A series of thin films of alkali tantalates were spin-coated onto Si-based substrates using diol-based routes. Interestingly, monophasic perovskite KTaO3 films deposited using KTOacac solution were obtained at temperature as low as 650 °C; films were annealed in rapid thermal furnace in oxygen atmosphere for 5 min with heating rate 30 °C/sec. Other compositions of the tantalum based system as LiTaO3 (LTO) and NaTaO3 (NTO), were successfully derived as well, onto Si substrates at 650 °C as well. The ferroelectric character of LTO at room temperature was proved. Some of dielectric properties of KTO could not be measured in parallel capacitor configuration due to either substrate-film or filmelectrode interfaces. Thus, further studies have to be conducted to overcome this issue. Application-oriented studies have also been conducted; two case studies: i) photocatalytic activity of alkali tantalates and niobates for decomposition of pollutant, and ii) bioactivity of alkali tantalate ferroelectric films as functional coatings for bone regeneration. Much attention has been recently paid to develop new type of photocatalytic materials, and tantalum and niobium oxide based compositions have demonstrated to be active photocatalysts for water splitting due to high potential of the conduction bands. Thus, various powders of alkali tantalates and niobates families were tested as catalysts for methylene blue degradation. Results showed promising activities for some of the tested compounds, and KNbO3 is the most active among them, reaching over 50 % degradation of the dye after 7 h under UVA exposure. However further modifications of powders can improve the performance. In the context of bone regeneration, it is important to have platforms that with appropriate stimuli can support the attachment and direct the growth, proliferation and differentiation of the cells. In lieu of this here we exploited an alternative strategy for bone implants or repairs, based on charged mediating signals for bone regeneration. This strategy includes coating metallic 316L-type stainless steel (316L-SST) substrates with charged, functionalized via electrical charging or UV-light irradiation, ferroelectric LiTaO3 layers. It was demonstrated that the formation of surface calcium phosphates and protein adsorption is considerably enhanced for 316L-SST functionalized ferroelectric coatings. Our approach can be viewed as a set of guidelines for the development of platforms electrically functionalized that can stimulate tissue regeneration promoting direct integration of the implant in the host tissue by bone ingrowth and, hence contributing ultimately to reduce implant failure.

LATERAL BRANCHING OXIDOREDUCTASE acts in the final stages of strigolactone biosynthesis inArabidopsis

Strigolactones are a group of plant compounds of diverse but related chemical structures. They have similar bioactivity across a broad range of plant species, act to optimize plant growth and development, and promote soil microbe interactions. Carlactone, a common precursor to strigolactones, is produced by conserved enzymes found in a number of diverse species. Versions of the MORE AXILLARY GROWTH1 (MAX1) cytochrome P450 from rice and Arabidopsis thaliana make specific subsets of strigolactones from carlactone. However, the diversity of natural strigolactones suggests that additional enzymes are involved and remain to be discovered. Here, we use an innovative method that has revealed a missing enzyme involved in strigolactone metabolism. By using a transcriptomics approach involving a range of treatments that modify strigolactone biosynthesis gene expression coupled with reverse genetics, we identified LATERAL BRANCHING OXIDOREDUCTASE (LBO), a gene encoding an oxidoreductase-like enzyme of the 2-oxoglutarate and Fe(II)-dependent dioxygenase superfamily. Arabidopsis lbo mutants exhibited increased shoot branching, but the lbo mutation did not enhance the max mutant phenotype. Grafting indicated that LBO is required for a graft-transmissible signal that, in turn, requires a product of MAX1. Mutant lbo backgrounds showed reduced responses to carlactone, the substrate of MAX1, and methyl carlactonoate (MeCLA), a product downstream of MAX1. Furthermore, lbo mutants contained increased amounts of these compounds, and the LBO protein specifically converts MeCLA to an unidentified strigolactone-like compound. Thus, LBO function may be important in the later steps of strigolactone biosynthesis to inhibit shoot branching in Arabidopsis and other seed plants.

Identification and Characterization of New Small Molecule Inhibitors of Picornavirus Replication

The Picornaviridae family consists of positive-strand RNA viruses that are the causative agents of a variety of diseases in humans and animals. Few drugs targeting picornaviruses are available, making the discovery of new antivirals a high priority. Here, we identified and characterized three compounds from a library of kinase inhibitors that block replication of poliovirus, coxsackievirus B3, and encephalomyocarditis virus. The antiviral effect of these compounds is not likely related to their known cellular targets because other inhibitors targeting the same pathways did not inhibit viral replication. Using an in vitro translation-replication system, we showed that these drugs inhibit different stages of the poliovirus life cycle. A4(1) inhibited the formation of a functional replication complex, while E5(1) and E7(2) affected replication after the replication complex had formed. A4(1) demonstrated partial protection from paralysis in a murine model of poliomyelitis. Poliovirus resistant to E7(2) had a single mutation in the 3A protein. This mutation was previously found to confer resistance to enviroxime-like compounds, which target either PI4KIIIβ (major enviroxime-like compounds) or OSBP (minor enviroxime-like compounds), cellular factors involved in lipid metabolism and shown to be important for replication of diverse positive-strand RNA viruses. We classified E7(2) as a minor enviroxime-like compound, because the localization of OSBP changed in the presence of this inhibitor. Interestingly, both E7(2) and major enviroxime-like compound GW5074 interfered with the viral polyprotein processing. Multiple attempts to isolate resistant mutants in the presence of A4(1) or E5(1) were unsuccessful, showing that effective broad-spectrum antivirals could be developed on the basis of these compounds. Studies with these compounds shed light on pathways shared by diverse picornaviruses that could be potential targets for the development of broad-spectrum antiviral drugs.

Potencial terapêutico de um heparinóide isolado do invertebrado marinho Litopenaeus vannamei

The occurrence of bioactive compounds in marine organisms comes awaking the interest of the pharmaceutical industry. Heparin, a sulfated polysaccharide which presence was already identified in several marine invertebrates, is very attractive due its remarkable functional versatility. Besides to intervene in blood coagulation, this molecule has a great anti-inflammatory potential. However, its strong anticoagulant activity difficult the clinical exploitation of its anti-inflammatory properties. Thus, the aims of this work were to evaluate the effect of a heparin-like compound (heparinoid), isolated from the cephalotorax of the Litopenaeus vannamei shrimp, on the inflammatory response, hemostasia and synthesis of antithrombotic heparan sulfate by endothelial cells, besides studying some aspects concerning its structure. The purified heparinoid was structurally characterized following an analytical boarding, involving electrophoresis and chromatography. The structural analysis have shown that this compound possess a high content of glucuronic acid residues and disulfated disaccharide units. In contrast to mammalian heparin, the heparinoid was incapable to stimulate the synthesis of heparan sulfate by endothelial cells in the tested concentrations, beyond to show reduced anticoagulant activity and hemorrhagic effect. In a model of acute inflammation, the compound isolated from the shrimp reduced more than 50% of the cellular infiltration. Besides reduce the activity of MMP-9 and proMMP-2 of the peritoneal lavage of inflamed animals, the heparinoid also reduced the activity of MMP-9 secreted by activated human leukocytes. These results demonstrate the potential of heparinoid from L. vannamei to intervene in the inflammatory response. For possessing reduced anticoagulant activity and hemorrhagic effect, this compound can serve as a structural model to direct the development of more specific therapeutical agents to the treatment of inflammatory diseases

Avaliação do efeito do composto tipo heparina isolado do caranguejo Chaceon fenneri na hemostasia e na morte celular

Heparin is a pharmaceutical animal widely used in medicine due to its potent anticoagulant effect. Furthermore, it has the ability to inhibit the proliferation, invasion and adhesion of cancer cells to vascular endothelium. However, its clinical applicability can be compromised by side effects such as bleeding. Thus, the search for natural compounds with low bleeding risk and possible therapeutic applicability has been targeted by several research groups. From this perspective, this study aims to evaluate the hemorrhagic and anticoagulant activities and citotoxic effect for different tumor cell lines (HeLa, B16-F10, HepG2, HS-5,) and fibroblast cells (3T3) of the Heparin-like from the crab Chaceon fenneri (HEP-like). The HEP-like was purified after proteolysis, ion-exchange chromatography, fractionation with acetone and characterized by electrophoresis (agarose gel) and enzymatic degradation. Hep-like showed eletroforetic behavior similar to mammalian heparin, and high trisulfated /Nacetylated disaccharides ratio. In addition, HEP-like presented low in vitro anticoagulant activity using aPTT and a minor hemorrhagic effect when compared to mammalian heparin. Furthermore, the HEP-like showed significant cytotoxic effect (p<0.001) on HeLa, HepG2 and B16-F10 tumor cells with IC50 values of 1000 ug/mL, after incubation for 72 hours. To assess the influence of heparin-like on the cell cycle in HeLa cells, analysis was performed by flow cytometry. The results of this analysis showed that HEP-like influence on the cell cycle increasing S phase and decreasing phase G2. Thus, these properties of HEP-like make these compounds potential therapeutic agents

Polissacarídeos sulfatados de interesse farmacológico no camarão litopenaeus schimitti

Sulfated Polysaccharides with unique chemical structures and important biological activities has been found in a diversity of sea invertebrates. For that, to exist a huger interest on the biotechnology field in the research theses sulfated compounds isolated from sea organisms. Despite the privileged brazilian position for these compounds attainment, there are still a few scientific informations about the isolated substances and their biological activities. A head the displayed, the present work has for objectives, to evaluate the pharmacological properties of the glycosaminoglycans isolated from the sea shrimp Litopenaeus schimitti on homeostasis, blood coagulation, leukocytes migration and platelet/leukocyte adhesion. For this, yhe glycosaminoglycans were extracted from crustacean tissues by proteolysis, fractionation with acetone and later submitted to pharmacological assays. The crustacean tissues showed compounds heparin-like, with anticoagulant activity of 45 IU/mg and 90 IU/mg, respectively. These molecules showed low residual hemorrhagic effects in the tested concentration (100 µg/mL), when compared to unfractionated commercial heparin (UFH). Another dermatan sulfate-like compound, predominately constituted for disulfated disaccharides, was isolated from crustacean abdomen. This compound showed an efficient effect on leukocytes migration inhibition, in the concentration of 15 µg/mL, reducing the cellular infiltration in 65% when compared to the controlled animals. In this same concentration, the DS reduced in 60% the protein concentration of the peritoneal exudates. In the concentration, this compound of 0.5 mg/mL, it was capable to reduce in 40% platelet/leukocytes adhesion. Our data demonstrate that these sulfated polysaccharides isolated from the shrimp L. schimitti will can be used as bioactive compounds, appearing as active principles for pharmacological development, anticoagulants and inflammatory response regulators

Avaliação do potencial anti-inflamatório de composto tipo heparina (cCTH) extraído do caranguejo Goniopsis cruentata em modelo experimental de peritonite

Heparin, a sulfated polysaccharide, was the first compound used as an anticoagulant and antithrombotic agent. Due to their structural characteristics, also has great potential anti-inflammatory, though such use is limited in inflammation because of their marked effects on coagulation. The occurrence of heparin-like compounds that exhibit anticoagulant activity decreased in aquatic invertebrates, such as crab Goniopsis cruentata, sparked interest for the study of such compounds as anti-inflammatory drugs. Therefore, the objective of this study was to evaluate the potential modulator of heparin-like compound extracted from Goniopsis cruentata in inflammatory events, coagulation, and to evaluate some aspects of its structure. The heparin-type compound had a high degree of N-sulphation in its structure, being able to reduce leukocyte migration into the peritoneal cavity at lower doses compared to heparin and diclofenac sodium (anti-inflammatory commercial). Furthermore, it was also able to inhibit the production of nitric oxide and tumor necrosis factor alpha by activated macrophages, inhibited the activation of the enzyme neutrophil elastase in low concentrations and showed a lower anticoagulant effect in high doses as compared to porcine mucosal heparin. Because of these observations, the compound extracted from crab Goniopsis cruentata can be used as a structural model for future anti-inflammatory agents

Potencial terapêutico de um heparinóide isolado do invertebrado marinho Litopenaeus vannamei

The occurrence of bioactive compounds in marine organisms comes awaking the interest of the pharmaceutical industry. Heparin, a sulfated polysaccharide which presence was already identified in several marine invertebrates, is very attractive due its remarkable functional versatility. Besides to intervene in blood coagulation, this molecule has a great anti-inflammatory potential. However, its strong anticoagulant activity difficult the clinical exploitation of its anti-inflammatory properties. Thus, the aims of this work were to evaluate the effect of a heparin-like compound (heparinoid), isolated from the cephalotorax of the Litopenaeus vannamei shrimp, on the inflammatory response, hemostasia and synthesis of antithrombotic heparan sulfate by endothelial cells, besides studying some aspects concerning its structure. The purified heparinoid was structurally characterized following an analytical boarding, involving electrophoresis and chromatography. The structural analysis have shown that this compound possess a high content of glucuronic acid residues and disulfated disaccharide units. In contrast to mammalian heparin, the heparinoid was incapable to stimulate the synthesis of heparan sulfate by endothelial cells in the tested concentrations, beyond to show reduced anticoagulant activity and hemorrhagic effect. In a model of acute inflammation, the compound isolated from the shrimp reduced more than 50% of the cellular infiltration. Besides reduce the activity of MMP-9 and proMMP-2 of the peritoneal lavage of inflamed animals, the heparinoid also reduced the activity of MMP-9 secreted by activated human leukocytes. These results demonstrate the potential of heparinoid from L. vannamei to intervene in the inflammatory response. For possessing reduced anticoagulant activity and hemorrhagic effect, this compound can serve as a structural model to direct the development of more specific therapeutical agents to the treatment of inflammatory diseases

Griffiths phase-like behavior and spin-phonon coupling in double perovskite Tb(2)NiMnO(6)

The Griffiths phase-like features and the spin-phonon coupling effects observed in Tb(2)NiMnO(6) are reported. The double perovskite compound crystallizes in monoclinic P2(1)/n space group and exhibits a magnetic phase transition at T(c) similar to 111 K as an abrupt change in magnetization. A negative deviation from ideal Curie-Weiss law exhibited by 1/chi(T) curves and less-than-unity susceptibility exponents from the power-law analysis of inverse susceptibility are reminiscent of Griffiths phase-like features. Arrott plots derived from magnetization isotherms support the inhomogeneous nature of magnetism in this material. The observed effects originate from antiferromagnetic interactions that arise from inherent disorder in the system. Raman scattering experiments display no magnetic-order-induced phonon renormalization below Tc in Tb(2)NiMnO(6), which is different from the results observed in other double perovskites and is correlated to the smaller size of the rare earth. The temperature evolution of full-width-at-half-maximum for the stretching mode at 645 cm(-1) presents an anomaly that coincides with the magnetic transition temperature and signals a close connection between magnetism and lattice in this material. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671674]