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451.
Fernando C. Moraes Ivana Cesarino Dyovani Coelho Valber A. Pedrosa Sergio A. S. Machado 《Electroanalysis》2012,24(5):1115-1120
An easy way to determine norepinephrine (NE) in biological fluid using a platinum ultramicroelectrode array (Pt‐UMEAs) is described. Issues related to UME electrode surface treatment and characterizations are also addressed. At optimized experimental conditions the dynamic concentration range was 1.0 to 10.0 µmol L?1 with a detection limit of 40.5 nmol L?1. The repeatability of current responses for injections of 5 µmol L?1 NE was evaluated to be 4.0 % (n=10). This approach obtained excellent sensitivity, a reliable calibration profile and stable electrochemical response for norepinephrine detection. The content of NE in urine samples without any preconcentration, purification, or pretreatment step, was successfully analyzed by the standard addition method using the Pt‐UMEAs. 相似文献
452.
Alex Neves Junior Romildo Dias Toledo Filho Eduardo de Moraes Rego Fairbairn Jo Dweck 《Journal of Thermal Analysis and Calorimetry》2012,108(2):725-731
Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to analyze the early stages of hydration of a high-initial
strength and sulphate resistant Portland cement (HS SR PC) within the first 24 h of setting. The water/cement (W/C) mass ratios
used to prepare the pastes were 0.35, 0.45, and 0.55. The hydration behavior of the pastes was analyzed through TG and DTG
curves obtained after different hydration times on calcined cement mass basis to have a same composition basis to compare
the data. The influence of the W/C ratio on the kinetics of the hydration process was done through the quantitative analysis
of the combined water of the main hydration products formed in each case. TG and DTG curves data calculated on calcined mass
basis of all the results were converted to initial cement mass basis to have an easier way to analyze the influence of the
W/C ratio on the free and combined water of the different main hydrated phases. The gypsum content of the pastes was totally
consumed in 8 h for all cases. A significant part of the hydration process occurs within the first 14 h of setting and at
24 h the highest hydration degree, indicated by the respective content of formed calcium hydroxide, occurs in the case of
the highest initial water content of the paste. 相似文献
453.
Costa EV Dutra LM Nogueira PC Moraes VR Salvador MJ Ribeiro LH Gadelha FR 《Natural product communications》2012,7(2):265-266
The essential oil from the leaves of Annona vepretorun was obtained by hydrodistillation using a Clevenger-type apparatus and analyzed by GC-MS and GC-FID. Eighteen compounds representing 98.1% of the crude essential oil were identified. The major compounds identified were bicyclogermacrene (43.7%), spathulenol (11.4%), alpha-felandrene (10.0%), alpha-pinene (7.1%), (E)-beta-ocimene (6.8%), germacrene D (5.8%), and p-cymene (4.2%). The trypanocidal activity against Trypanosoma cruzi epimastigote forms, as well as, the antimicrobial and antioxidant proprieties was investigated. The essential oil showed a potent trypanocidal activity with IC50 value of 31.9 +/-1.3 microg x mL(-1). For antimicrobial activity, the best result was observed against Candida tropicalis with a MIC value of 100 microg x mL(-1). For antioxidant capacity the essential oil showed weak activity. 相似文献
454.
Erick de Moraes Franklin 《Applied Mathematical Modelling》2012,36(3):1057-1067
Granular media are frequently found in nature and in industry and their transport by a fluid flow is of great importance to human activities. One case of particular interest is the transport of sand in open-channel and river flows. In many instances, the shear stresses exerted by the fluid flow are bounded to certain limits and some grains are entrained as bed-load: a mobile layer which stays in contact with the fixed part of the granular bed. Under these conditions, an initially flat granular bed may be unstable, generating ripples and dunes such as those observed on the bed of rivers. In free-surface water flows, dunes are bedforms that scale with the flow depth, while ripples do not scale with it. This article presents a model for the formation of ripples and dunes based on the proposition that ripples are primary linear instabilities and that dunes are secondary instabilities formed from the competition between the coalescence of ripples and free surface effects. Although simple, the model is able to explain the growth of ripples, their saturation (not explained in previous models) and the evolution from ripples to dunes, presenting a complete picture for the formation of dunes. 相似文献
455.
456.
Celeste de Jesus Pereira Franco Oberdan Oliveira Ferreira Jorddy Neves Cruz Everton Luiz Pompeu Varela ngelo Antnio Barbosa de Moraes Lidiane Diniz do Nascimento Mrcia Moraes Cascaes Antnio Pedro da Silva Souza Filho Rafael Rodrigues Lima Sandro Percrio Mozaniel Santana de Oliveira Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2022,27(15)
The essential oil (EO) of Calycolpus goetheanus (Myrtaceae) specimens (A, B, and C) were obtained through hydrodistillation. The analysis of the chemical composition of the EOs was by gas chromatography coupled with mass spectrometry CG-MS, and gas chromatography coupled with a flame ionization detector CG-FID. The phytotoxic activity of those EOs was evaluated against two weed species from common pasture areas in the Amazon region: Mimosa pudica L. and Senna obtusifolia (L.) The antioxidant capacity of the EOs was determined by (DPPH•) and (ABTS•+). Using molecular docking, we evaluated the interaction mode of the major EO compounds with the molecular binding protein 4-hydroxyphenylpyruvate dioxygenase (HPPD). The EO of specimen A was characterized by β-eudesmol (22.83%), (E)-caryophyllene (14.61%), and γ-eudesmol (13.87%), while compounds 1,8-cineole (8.64%), (E)-caryophyllene (5.86%), δ-cadinene (5.78%), and palustrol (4.97%) characterize the chemical profile of specimen B’s EOs, and specimen C had α-cadinol (9.03%), δ-cadinene (8.01%), and (E)-caryophyllene (6.74%) as the majority. The phytotoxic potential of the EOs was observed in the receptor species M. pudica with percentages of inhibition of 30%, and 33.33% for specimens B and C, respectively. The EOs’ antioxidant in DPPH• was 0.79 ± 0.08 and 0.83 ± 0.02 mM for specimens A and B, respectively. In the TEAC, was 0.07 ± 0.02 mM for specimen A and 0.12 ± 0.06 mM for specimen B. In the results of the in silico study, we observed that the van der Waals and hydrophobic interactions of the alkyl and pi-alkyl types were the main interactions responsible for the formation of the receptor–ligand complex. 相似文献
457.
Adriano de Souza Carolino Matheus Moraes Biondo tefan lu Henrique Duarte da Fonseca Filho Pedro Henrique Campelo Jaqueline de Araújo Bezerra Cicero Mota Hidembergue Ordozgoith da Frota Vanderlei Salvador Bagnato Natalia Mayumi Inada Edgar Aparecido Sanches 《Molecules (Basel, Switzerland)》2022,27(15)
The development of conjugated polymer-based nanocomposites by adding metallic particles into the polymerization medium allows the proposition of novel materials presenting improved electrical and optical properties. Polyaniline Emeraldine-salt form (ES–PANI) has been extensively studied due to its controllable electrical conductivity and oxidation states. On the other hand, tungsten oxide (WO3) and its di-hydrated phases, such as WO3·2H2O, have been reported as important materials in photocatalysis and sensors. Herein, the WO3·2H2O phase was directly obtained during the in-situ polymerization of aniline hydrochloride from metallic tungsten (W), allowing the formation of hybrid nanocomposites based on its full oxidation into WO3·2H2O. The developed ES–PANI–WO3·2H2O nanocomposites were successfully characterized using experimental techniques combined with Density Functional Theory (DFT). The formation of WO3·2H2O was clearly verified after two hours of synthesis (PW2 nanocomposite), allowing the confirmation of purely physical interaction between matrix and reinforcement. As a result, increased electrical conductivity was verified in the PW2 nanocomposite: the DFT calculations revealed a charge transfer from the p-orbitals of the polymeric phase to the d-orbitals of the oxide phase, resulting in higher conductivity when compared to the pure ES–PANI. 相似文献
458.
Geovane de Almeida Santos da Silva José Roberto Moraes d'Almeida Sonia Letichevsky Roberto Ribeiro de Avillez 《先进技术聚合物》2023,34(1):145-154
This work studies the crystallinity and rheology of HDPE/PA12 blends compatibilized with 2 wt% of HDPE-alt-MAH. Specimens of HDPE/PA12 blends were extruded and injected into a mold with 75/25, 50/50, and 25/75 HDPE/PA ratios. The Fourier-transform infrared spectroscopy (FTIR) analysis showed that no oxidation reaction occurred in the high-temperature processing and that stronger interactions between the components of the blends occurred in the polyamide's functional groups. The x-ray diffraction (XRD) analysis showed that the crystallinity degree of the blends and the mean crystallite sizes decreased with the addition of PA12 for both blends. The HDPE's lattice parameters were consistent with the values in the literature, whereas for the PA12, it was not possible to fit its lattice parameters. The rheology analysis evaluated the relationship between the shear stress and viscosity and found that the HDPE/PA 75/25 blend was the most pseudoplastic, presenting the best processability under high shear rates. 相似文献