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51.
Gabriel Rocha Martins Douglas Guedes Urbano Luiz Marques de Paula Maria do Socorro Padilha de Oliveira Marcia Teresa Soares Lutterbach Leila Yone Reznik Eliana Flvia Camporese Srvulo Celuta Sales Alviano Antonio Jorge Ribeiro da Silva Daniela Sales Alviano 《Molecules (Basel, Switzerland)》2021,26(11)
Euterpe oleracea Mart. (Arecaceae) is an endogenous palm tree from the Amazon region. Its seeds correspond to 85% of the fruit’s weight, a primary solid residue generated from pulp production, the accumulation of which represents a potential source of pollution and environmental problems. As such, this work aimed to quantify and determine the phytochemical composition of E. oleracea Mart. seeds from purple, white, and BRS-Pará açaí varieties using established analytical methods and also to evaluate it as an eco-friendly corrosion inhibitor. The proanthocyanidin quantification (n-butanol/hydrochloric acid assay) between varieties was 6.4–22.4 (w/w)/dry matter. Extract characterization showed that all varieties are composed of B-type procyanidin with a high mean degree of polymerization (mDP ≥ 10) by different analytical methodologies to ensure the results. The purple açaí extract, which presented 22.4% (w/w) proanthocyanidins/dry matter, was tested against corrosion of carbon steel AISI 1020 in neutral pH. The crude extract (1.0 g/L) was effective in controlling corrosion on the metal surface for 24 h. Our results demonstrated that the extracts rich in polymeric procyanidins obtained from industrial açaí waste could be used to inhibit carbon steel AISI 1020 in neutral pH as an abundant, inexpensive, and green source of corrosion inhibitor. 相似文献
52.
Igor T. Padilha 《Journal of magnetism and magnetic materials》2009,321(20):3466-3471
In multi-band superconductors as inter-metallic systems and heavy fermions, external pressure can reduce the critical temperature and eventually destroy superconductivity driving these systems to the normal state. In many cases this transition is continuous and is associated with a superconducting quantum critical point (SQCP). In this work we study a two-band superconductor in the presence of hybridization V. This one-body mixing term is due to the overlap of the different wave-functions. It can be tuned by external pressure and turns out as an important control parameter to study the phase diagram and the nature of the phase transitions. We use a BCS approximation and include both inter- and intra-band attractive interactions. For negligible inter-band interactions, as hybridization (pressure) increases we find a SQCP separating a superconductor from a normal state at a critical value of the hybridization Vc. We obtain the behavior of the electronic specific heat close to the SQCP and the shape of the critical line as V approaches Vc. 相似文献
53.
Santos LS Padilha MC de Aquino Neto FR Santos Pereira AD Menegatti R Manssour Fraga CA Barreiro EJ Eberlin MN 《Journal of mass spectrometry : JMS》2005,40(6):815-820
Recently, two analogous series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines have been prepared and found to be potential antipsychotic drugs acting as new selective ligands of the dopamine D2 receptor. Herein we report a systematic study of their high-resolution electrospray ionization mass and tandem mass spectra in which the main dissociation routes of their protonated molecules are determined and rationalized. The ESI-MS/MS data is very characteristic for both series allowing straightforward isomeric differentiation. A single and dominant fragment ion for the pyrazole series and four major fragment ions for the triazole series are useful for selective reaction MS monitoring of these potential drugs in biological fluids. 相似文献
54.
Felipe A. Santos Paula M. Lima Renato C. F. Neves Paula M. Moraes Carlos A. P��rez Marcelo O. A. Silva Marco A. Z. Arruda Gustavo R. Castro Pedro de Magalh?es Padilha 《Mikrochimica acta》2011,173(1-2):43-49
An investigation was made on plasma samples obtained after protein separation. The proteome of the plasma of Nile tilapia (Oreochromis niloticus) was separated by 2D PAGE, and manganese and zinc in protein spots was qualitatively and quantitatively determined by synchrotron radiation X-ray fluorescence (SR-XRF) and graphite furnace atomic absorption spectrometry (GFAAS). Manganese and zinc are present in four and six plasma protein spots, respectively. These ions are bound to proteins with molecular weights ranging from 19 to 70?kDa and with isoelectric point (pI) ranging from 4.7 to 6.3. The concentrations of manganese and zinc bound to these proteins as determined by GFAAS following acid digestion of the spots range from 0.8 to 2.6?mg of manganese, and from 1.0 to 6.3?mg of zinc, respectively, per g of protein. Figure
2D-Page Plasma 相似文献
55.
The search for Majorana fermions has been concentrated in topological insulators or superconductors. In general, the existence of these modes requires the presence of spin–orbit interactions and of an external magnetic field. The former implies in having systems with broken inversion symmetry, while the latter breaks time reversal invariance. In a recent paper, we have shown that a two-band metal with an attractive inter-band interaction has non-trivial superconducting properties, if the k-dependent hybridization is anti-symmetric in the wave-vector. This is the case, if the crystalline potential mixes states with different parities as for orbitals with angular momentum l and l+1. In this paper we take into account the effect of an external magnetic field, not considered in the previous investigation, in a two-band metal and show how it modifies the topological properties of its superconducting state. We also discuss the conditions for the appearance of Majorana fermions in this system. 相似文献
56.
Denilson de Jesus Assis Líllian Vasconcelos Brandão Larissa Alves de Sousa Costa Tamiris Vilas Boas Figueiredo Luciane Santos Sousa Francine Ferreira Padilha Janice Izabel Druzian 《Applied biochemistry and biotechnology》2014,172(5):2769-2785
The effects of aeration and agitation on the properties and production of xanthan gum from crude glycerin biodiesel (CGB) by Xanthomonas campestris mangiferaeindicae 2103 were investigated and optimized using a response surface methodology. The xanthan gum was produced from CGB in a bioreactor at 28 °C for 120 h. Optimization procedures indicated that 0.97 vvm at 497.76 rpm resulted in a xanthan gum production of 5.59 g L?1 and 1.05 vvm at 484.75 rpm maximized the biomass to 3.26 g L?1. Moreover, the combination of 1.05 vvm at 499.40 rpm maximized the viscosity of xanthan at 0.5 % (m/v), 25 °C, and 25 s?1 (255.40 mPa s). The other responses did not generate predictive models. Low agitation contributed to the increase of xanthan gum production, biomass, viscosity, molecular mass, and the pyruvic acid concentration. Increases in the agitation contributed to the formation of xanthan gum with high mannose concentration. Decreases in the aeration contributed to the xanthan gum production and the formation of biopolymer with high mannose and glucose concentrations. Increases in aeration contributed to increased biomass, viscosity, and formation of xanthan gum with greater resistance to thermal degradation. Overall, aeration and agitation of CGB fermentation significantly influenced the production of xanthan gum and its properties. 相似文献
57.
Gustavo R. Castro Valtair M. Cristante Cilene C. F. Padilha Sônia M. A. Jorge Ariovaldo O. Florentino Alexandre G. S. Prado Pedro M. Padilha 《Mikrochimica acta》2008,160(1-2):203-209
This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT) and the studies of adsorption
and pre-concentration (in batch and using a flow-injection system coupled with optical emission spectrometer) of Cd(II), Cu(II)
and Ni(II) in aqueous medium. The adsorption capacity for each metal ions in mmol g−1 was: Cu(II) = 1.18, Ni(II) = 1.15 and Cd(II) = 1.10. The results obtained in the flow experiments showed about 100% of recovering
of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 μL of 2.0 mol L−1 HCl solution as eluent. The quantitative sorption–desorption of the metal ions made possible the application of a flow-injection
system in the pre-concentration and quantification by ICP-OES of metal ions at trace level in natural water samples.
Correspondence: Pedro M. Padilha, Departamento de Química e Bioquímica, I.B., UNESP, 18618-000 Botucatu, SP, Brazil 相似文献
58.
By performing density functional theory calculations we show that it is possible to make the electronic bandgap in bilayer graphene supported on hexagonal boron nitride (h-BN) substrates tunable. We also show that, under applied electric fields, it is possible to insert states from h-BN into the bandgap, which generate a conduction channel through the substrate making the system metallic. In addition, we verify that the breakdown voltage strongly depends on the number of h-BN layers. We also show that both the breakdown voltage and the bandgap tuning are independent of the h-BN stacking order. 相似文献