32 resultados para 10 K

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Coexistence between superconductivity and magnetism is reported for the KxMoO2-delta samples. Photoemission experiments show that the presence of Mo3+ ions is responsible for the weak ferromagnetic ordering observed in the KxMoO2-delta samples. Magnetic ordering temperature and superconducting critical temperature (T-C) ratio range from 7 to 18 in this compound. These are the highest ratios reported so far for a magnetic superconductor. T-C decreases with increasing potassium composition (x). For the first time, T-C near 10 K is reported in the K-Mo-O system. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757003]

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We investigated modulation by ATP, Mg2+, Na+, K+ and NH4 (+) and inhibition by ouabain of (Na+,K+)-ATPase activity in microsomal homogenates of whole zoeae I and decapodid III (formerly zoea IX) and whole-body and gill homogenates of juvenile and adult Amazon River shrimps, . (Na+,K+)-ATPase-specific activity was increased twofold in decapodid III compared to zoea I, juveniles and adults, suggesting an important role in this ontogenetic stage. The apparent affinity for ATP ( (M) = 0.09 +/- A 0.01 mmol L-1) of the decapodid III (Na+,K+)-ATPase, about twofold greater than the other stages, further highlights this relevance. Modulation of (Na+,K+)-ATPase activity by K+ also revealed a threefold greater affinity for K+ ( (0.5) = 0.91 +/- A 0.04 mmol L-1) in decapodid III than in other stages; NH4 (+) had no modulatory effect. The affinity for Na+ ( (0.5) = 13.2 +/- A 0.6 mmol L-1) of zoea I (Na+,K+)-ATPase was fourfold less than other stages. Modulation by Na+, Mg2+ and NH4 (+) obeyed cooperative kinetics, while K+ modulation exhibited Michaelis-Menten behavior. Rates of maximal Mg2+ stimulation of ouabain-insensitive ATPase activity differed in each ontogenetic stage, suggesting that Mg2+-stimulated ATPases other than (Na+,K+)-ATPase are present. Ouabain inhibition suggests that, among the various ATPase activities present in the different stages, Na+-ATPase may be involved in the ontogeny of osmoregulation in larval The NH4 (+)-stimulated, ouabain-insensitive ATPase activity seen in zoea I and decapodid III may reflect a stage-specific means of ammonia excretion since functional gills are absent in the early larval stages.

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OBJETIVO: O principal objetivo deste trabalho é avaliar a ingestão habitual de vitamina K em adultos e idosos. MÉTODOS: Foi realizado um estudo transversal com a participação de 173 indivíduos de ambos os sexos. A ingestão habitual de cada participante foi avaliada pela aplicação de três recordatórios 24h não consecutivos. As variabilidades intra e interpessoal foram avaliadas por meio do software PC-SIDE. RESULTADOS: A média de ingestão de vitamina K na amostra foi de 110,7µg/dia, com uma mediana de 99µg/dia; os idosos foram os que apresentaram maiores valores de ingestão, com uma mediana de 104µg/dia. O consumo de vitamina K entre adultos e idosos foi estatisticamente diferente (p=0,00), e o consumo de hortaliças apresentou forte correlação com o consumo de vitamina K total. CONCLUSÃO: Independentemente da faixa etária e do sexo, a ingestão de vitamina K foi insuficiente em quase metade da amostra, o que pode ocasionar um maior risco de inadequação dietética e acarretar problemas ósseos no futuro e/ou agravar os já presentes quando se trata da população idosa.

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We examine hemolymph ion regulation and the kinetic properties of a gill microsomal (Na+, K+)-ATPase from the intertidal hermit crab, Clibanarius vittatus, acclimated to 45 parts per thousand salinity for 10 days. Hemolymph osmolality is hypo-regulated (1102.5 +/- 22.1 mOsm kg(-1) H2O) at 45 parts per thousand but elevated compared to fresh-caught crabs (801.0 +/- 40.1 mOsm kg(-1) H2O). Hemolymph [Na+ (323.0 +/- 2.5 mmol L-1) and [Me2+) (34.6 +/- 1.0 mmol L-1) are hypo-regulated while [Ca2+] (22.5 +/- 0.7 mmol L-1) is hyper-regulated; [K+] is hyper-regulated in fresh-caught crabs (17.4 +/- 0.5 mmol L-1) but hypo-regulated (6.2 +/- 0.7 mmol L-1) at 45 parts per thousand. Protein expression patterns are altered in the 45 parts per thousand-acclimated crabs, although Western blot analyses reveal just a single immunoreactive band, suggesting a single (Na+, K+)-ATPase alpha-subunit isoform, distributed in different density membrane fractions. A high-affinity (Vm = 46.5 +/- 3.5 U mg(-1); K-0.5 = 7.07 +/- 0.01 mu mol L-1) and a low-affinity ATP binding site (Vm = 108.1 +/- 2.5 U mg(-1); K-0.5 = 0.11 +/- 0.3 mmol L-1), both obeying cooperative kinetics, were disclosed. Modulation of (Na+, K+)-ATPase activity by Mg2+, K+ and NH4+ also exhibits site-site interactions, but modulation by Na+ shows Michaelis-Menten kinetics. (Na+, K+)-ATPase activity is synergistically stimulated up to 45% by NH4+ plus K+. Enzyme catalytic efficiency for variable [K+] and fixed [NH4+] is 10-fold greater than for variable [NH4+] and fixed [K+]. Ouabain inhibited approximate to 80% of total ATPase activity (K-I=464.7 +/- 23.2 mu mol L-1), suggesting that ATPases other than (Na+, K+)-ATPase are present. While (Na+, K+)-ATPase activities are similar in fresh-caught (around 142 nmol Pi min(-1) mg(-1)) and 45 parts per thousand-acclimated crabs (around 154 nmol Pi min(-1) mg(-1)), ATP affinity decreases 110-fold and Na+ and K+ affinities increase 2-3-fold in 45 parts per thousand-acclimated crabs. (C) 2012 Elsevier Inc. All rights reserved.

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Crotalphine, a 14 amino acid peptide first isolated from the venom of the South American rattlesnake Crotalus durissus terrificus, induces a peripheral long-lasting and opioid receptor-mediated antinociceptive effect in a rat model of neuropathic pain induced by chronic constriction of the sciatic nerve. In the present study, we further characterized the molecular mechanisms involved in this effect, determining the type of opioid receptor responsible for this effect and the involvement of the nitric oxide-cyclic GMP pathway and of K+ channels. Crotalphine (0.2 or 5 mu g/kg, orally; 0.0006 mu g/paw), administered on day 14 after nerve constriction, inhibited mechanical hyperalgesia and low-threshold mechanical allodynia. The effect of the peptide was antagonized by intraplantar administration of naltrindole, an antagonist of delta-opioid receptors, and partially reversed by norbinaltorphimine, an antagonist of kappa-opioid receptors. The effect of crotalphine was also blocked by 7-nitroindazole, an inhibitor of the neuronal nitric oxide synthase; by 1H-(1,2,4) oxadiazolo[4,3-a]quinoxaline-1-one, an inhibitor of guanylate cyclase activation; and by glibenclamide, an ATP-sensitive K+ channel blocker. The results suggest that peripheral delta-opioid and kappa-opioid receptors, the nitric oxide-cyclic GMP pathway, and ATP-sensitive K+ channels are involved in the antinociceptive effect of crotalphine. The present data point to the therapeutic potential of this peptide for the treatment of chronic neuropathic pain. Behavioural Pharmacology 23:14-24 (C) 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

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Investigating tree's spatial patterns according to their size classes and according to their more abundant species can provide evidences about the structure of the vegetal community, since the spatial pattern is a key question for forestry ecology studies. The tree spatial organization patterns on the environment depend on several ecological processes and on the specific characteristics of each environment, so that the best understanding of this frame provides important elements for the knowledge on forestry formation. This paper aimed to study tree spatial patterns, according to the diameter classes and from four most abundant species in different forests, in order to provide evidences regarding to the ecology of each vegetal community. The spatial pattern description in each forestry formation was developed using Ripley's K function. The studied forestry formations were: Ombrophilous Forest, Cerradao, Seasonal Forest and Restinga Forest. In this work, a 10.24 ha plot was installed in each forestry formation, and every tree, with a circumference at breast height (CBH) larger than 15 cm were measured, georeferenced and identified. The obtained data highlights the aggregated character in tropical forests, as observed in every studied forest. The 'Cerraddo' and 'Restinga' forest trees showed close aggregate patterns. In the Ombrophilous forest, for all distance scales, the aggregate pattern was meaningful. In the seasonal forest, a random tendency was observed, although a meaningful aggregation was observed in all short distances. The spatial pattern by diameter classes was generally aggregated for trees smaller than 10 cm of diameter and between 10 and 20 cm and random for the others, proving the existence of a tendency which in young trees is more aggregated than in old ones. The spatial pattern of the dominant species is always strongly similar to the general pattern of each forestry formation. The differences between the spatial patterns of two or three coincident species, among the forestry formations, indicate that its pattern is influenced by each different environment. This stands out the importance of its self-ecology and of its ecological processes, intrinsic of each community that can explain the observed patterns.

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We report on the investigation of the Ti2GeC properties by X-ray diffraction, magnetic and electrical resistivity measurements. Polycrystalline samples of Ti2GeC with nominal compositions were prepared by solid state reaction. X-ray powder patterns suggest that all peaks can be indexed with the hexagonal phase of Cr2AlC prototype. The temperature dependence of both electrical resistivity and magnetization indicate a bulk type-II superconductivity at 9.5 K. Magnetoresistive data suggest an upper critical field of B-c2 similar to 8.1 T and coherence length similar to 61 A degrees . Furthermore, the results highlight the highest critical temperature reported up to now for an H-phase.

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Vaccination with peptide 10 (P10), derived from the Paracoccidioides brasiliensis glycoprotein 43 (gp43), induces a Th1 response that protects mice in an intratracheal P. brasiliensis infection model. Combining P10 with complete Freund's adjuvant (CFA) or other adjuvants further increases the peptide's antifungal effect. Since dendritic cells (DCs) are up to 1,000-fold more efficient at activating T cells than CFA, we examined the impact of P10-primed bone-marrow-derived DC vaccination in mice. Splenocytes from mice immunized with P10 were stimulated in vitro with P10 or P10-primed DCs. T cell proliferation was significantly increased in the presence of P10-primed DCs compared to the peptide. The protective efficacy of P10-primed DCs was studied in an intratracheal P. brasiliensis model in BALB/c mice. Administration of P10-primed DCs prior to (via subcutaneous vaccination) or weeks after (via either subcutaneous or intravenous injection) P. brasiliensis infection decreased pulmonary damage and significantly reduced fungal burdens. The protective response mediated by the injection of primed DCs was characterized mainly by an increased production of gamma interferon (IFN-gamma) and interleukin 12 (IL-12) and a reduction in IL-10 and IL-4 compared to those of infected mice that received saline or unprimed DCs. Hence, our data demonstrate the potential of P10-primed DCs as a vaccine capable of both the rapid protection against the development of serious paracoccidioidomycosis or the treatment of established P. brasiliensis disease.

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Identical neutral kaon pair correlations are measured in root s = 7 TeV pp collisions in the ALICE experiment. One-dimensional (KsKs0)-K-0 correlation functions in terms of the invariant momentum difference of kaon pairs are formed in two multiplicity and two transverse momentum ranges. The femtoscopic parameters for the radius and correlation strength of the kaon source are extracted. The fit includes quantum statistics and final-state interactions of the a(0)/f(0) resonance. (KsKs0)-K-0 correlations show an increase in radius for increasing multiplicity and a slight decrease in radius for increasing transverse mass, mT, as seen in pi pi correlations in pp collisions and in heavy-ion collisions. Transverse mass scaling is observed between the (KsKs0)-K-0 and pi pi radii. Also, the first observation is made of the decay of the f(2)'(1525) meson into the (KsKs0)-K-0 channel in pp collisions. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

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The title compound [Ni(C20H15N2OS)(2)] is prepared by the reaction of metal acetate with the corresponding acylthiourea derivative. The complex is characterized by elemental analysis, IR, H-1 and C-13 NMR, and its structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O atoms of two N-benzoyl-N',N'-diphenylthiourea ligands in a slightly distorted square-planar coordination geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic (P-1 space group) with cell dimensions a = 10.7262(9) , b = 12.938(3) , c = 14.2085(12) , alpha = 74.650(4)A degrees, beta = 78.398(4)A degrees, gamma = 68.200(5)A degrees, and two formula units in the unit cell. The structure is very close to the related N-(2-furoyl) Ni complex reported previously.

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In this work, we have applied sub-Doppler laser cooling to a K-39 magneto-optical trap in order to load a 1071 nm crossed optical dipole trap. The number of atoms loaded into the dipole trap was characterized as a function of the frequency and intensity of the cooling and repump laser beams. For the optimum conditions, the dipole trap has about 2 x 10(6) atoms at an atomic density of 2 x 10(12) cm(-3), with a temperature of about 10 mu K. This technique is a very simple procedure to load a K-39 optical dipole trap without a previous magnetic evaporative cooling step and may find application in other atomic physic systems.

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This research reports liquid liquid equilibrium data for the system lard (swine fat), cis-9-octadecenoic acid (oleic acid), ethanol, and water at 318.2 K, as well as their correlation with the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) thermodynamic equations, which have provided global deviations of 0.41 % and 0.53 %, respectively. Additional equilibrium experiments were also performed to obtain cholesterol partition (or distribution) coefficients to verify the availability of the use of ethanol plus water to reduce the cholesterol content in lard. The partition experiments were performed with concentrations of free fatty acids (commercial oleic acid) that varied from (0 to 20) mass % and of water in the solvent that varied from (0 to 18) mass %. The percentage of free fatty acids initially present in lard had a slight effect on the distribution of cholesterol between the phases. Furthermore, the distribution coefficients decreased by adding water in the ethanol; specifically, it resulted in a diminution of the capability of the solvent to remove the cholesterol.

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For a locally compact Hausdorff space K and a Banach space X we denote by C-0(K, X) the space of X-valued continuous functions on K which vanish at infinity, provided with the supremum norm. Let n be a positive integer, Gamma an infinite set with the discrete topology, and X a Banach space having non-trivial cotype. We first prove that if the nth derived set of K is not empty, then the Banach-Mazur distance between C-0(Gamma, X) and C-0(K, X) is greater than or equal to 2n + 1. We also show that the Banach-Mazur distance between C-0(N, X) and C([1, omega(n)k], X) is exactly 2n + 1, for any positive integers n and k. These results extend and provide a vector-valued version of some 1970 Cambern theorems, concerning the cases where n = 1 and X is the scalar field.

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It is reported superconductivity in Nb5Ge3C0.3, an interstitial carbide compound. The temperature dependence of the electrical resistivity, ac-susceptibility, and heat capacity (HC) indicate that a bulk type-II superconductivity appears at T-C - 15.3 K. Magneto-resistance measurements suggest an upper critical field of B-C2 similar to 10.6 T and a coherence length of xi similar to 55 angstrom at zero temperature. Neutron diffraction analyzes locate the carbon atoms at the interstitial 2b site of the Mn5Si3 type-structure. Heat capacity data below T-C are well described by BCS theory. The size of the jump at T-C is in good agreement with the superconducting volume fraction observed in susceptibility measurements. A Debye temperature and Sommerfeld constant were also extracted from heat capacity data as 343 K and 34 mJ/mol K-2, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4730611]

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Crotamine, a 5-kDa peptide, possesses a unique biological versatility. Not only has its cell-penetrating activity become of clinical interest but, moreover, its potential selective antitumor activity is of great pharmacological importance. In the past, several studies have attempted to elucidate the exact molecular target responsible for the crotamine-induced skeletal muscle spasm. The aim of this study was to investigate whether crotamine affects voltage-gated potassium (K-V) channels in an effort to explain its in vivo effects. Crotamine was studied on ion channel function using the two-electrode voltage clamp technique on 16 cloned ion channels (12 K-V channels and 4 Na-V channels), expressed in Xenopus laevis oocytes. Crotamine selectively inhibits K-V 1.1, K-V 1.2, and K-V 1.3 channels with an IC50 of similar to 300 nM, and the key amino acids responsible for this molecular interaction are suggested. Our results demonstrate for the first time that the symptoms, which are observed in the typical crotamine syndrome, may result from the inhibition of K-V channels. The ability of crotamine to inhibit the potassium current through K-V channels unravels it as the first snake peptide with the unique multifunctionality of cell-penetrating and antitumoral activity combined with K-V channel-inhibiting properties. This new property of crotamine might explain some experimental observations and opens new perspectives on pharmacological uses.