Limit Cycles
Mostrando 1-12 de 69 artigos, teses e dissertações.
-
1. Development of a Disposable Pipette Extraction Method Using Coffee Silverskin as an Adsorbent for Chromium Determination in Wastewater Samples by Solid Phase Extraction
A procedure using disposable pipette tips adapted for solid-phase extraction, known as DPX SPE, was used as an alternative way for the chromium determination in wastewater samples. DPX-SPE consists of a device which allows a dynamic contact between the sample and the solid-phase. A residue obtained from the processing of coffee beans, denominate coffee silve
Journal of the Brazilian Chemical Society. Publicado em: 2022
-
2. Zeólita NaA sintetizada sobre fibra de vidro como estratégia para otimização do abrandamento de águas duras
NaA ZEOLITE SYNTHESIZED OVER FIBERGLASS AS A STRATEGY FOR OPTIMIZING HARD WATER SOFTENING. Zeolite NaA has been successfully synthesized over glass fiber surface previously activated by alkaline treatment. By varying the time of the treatment and the amount of silica and alumina precursors used in the reaction mixture, a sample with higher zeolite concentrat
Química Nova. Publicado em: 2022
-
3. ANODES FOR SOFC: REVIEW OF MATERIAL SELECTION, INTERFACE AND ELECTROCHEMICAL PHENOMENA
This paper presents a comprehensive interface and electrochemical phenomena review of different anodes for SOFC. In this way, it was possible to select some mixed electronic and ionic conductor materials alternatives to the conventional anode, Ni-YSZ conductor. New materials must present a satisfactory electronic and ionic conductivity at intermediate temper
Quím. Nova. Publicado em: 2021-01
-
4. Exploring Polypyrrole as Extraction Phase for Disposable Pipette Extraction Method for Multiclass Organic Micro-Pollutant Determination in River and Tap Water Using Gas Chromatography-Mass Spectrometry
The use of a polypyrrole (PPy) is described as an efficient extraction phase for disposable pipette extraction (DPX), in a fast and ruggedized analytical method for simultaneous determination of 18 organic micro-pollutants in water using gas chromatography-mass spectrometry (GC-MS). The DPX-blank pipettes were filled with PPy, a material produced through the
J. Braz. Chem. Soc.. Publicado em: 2020-10
-
5. LC-UV method to assay raloxifene hydrochloride in rat plasma and its application to a pharmacokinetic study
A specific, precise, and accurate LC-UV method was developed and validated to assay raloxifene hydrochloride in rat plasma. Raloxifene was analyzed after liquid-liquid extraction and quantified by reversed phase liquid chromatography (C18 column) using acetonitrile and ammonium acetate buffer 0.05 M (pH 4.0) as mobile phase at a flow rate of 1 mL.min-1 and U
Braz. J. Pharm. Sci.. Publicado em: 30/09/2019
-
6. A New Method for the Determination of Creatinine in Urine Samples Based on Disposable Pipette Extraction
A method based on disposable pipette extraction (DPX) was successfully applied to creatinine determination in urine samples analysis using liquid chromatography with ultraviolet spectrophotometric detection (DPX/LC-UV). DPX variables, number of draw/eject cycles, sample pH, and type of the desorption solvent, were employed in a factorial experimental design
J. Braz. Chem. Soc.. Publicado em: 2018-04
-
7. Organic solvent exposure and contrast sensitivity: comparing men and women
The goal of this study was to compare the visual contrast sensitivity (CS) of men and women exposed and not exposed to organic solvents. Forty-six volunteers of both genders aged between 18 and 41 years (mean±SD=27.72±6.28) participated. Gas station attendants were exposed to gas containing 46.30 ppm of solvents at a temperature of 304±274.39 K, humidity
Braz J Med Biol Res. Publicado em: 11/01/2018
-
8. Genetic progress after cycles of upland rice recurrent selection
Periodic assessment of the genetic progress made in recurrent selection programs is essential for assessing the evolution of the programs and identifying the main factors that have contributed to this progress. This study aimed to estimate genetic progress in grain yield, plant height and days-to-flowering achieved in the CNA6 population of upland rice (Oryz
Sci. agric. (Piracicaba, Braz.). Publicado em: 2015-08
-
9. State estimation of chemical engineering systems tending to multiple solutions
A well-evaluated state covariance matrix avoids error propagation due to divergence issues and, thereby, it is crucial for a successful state estimator design. In this paper we investigate the performance of the state covariance matrices used in three unconstrained Extended Kalman Filter (EKF) formulations and one constrained EKF formulation (CEKF). As bench
Braz. J. Chem. Eng.. Publicado em: 2014-09
-
10. Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading
Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. OBJECTIVE: The aim of this study was to investigate the failure mode and the influence of exten
J. Appl. Oral Sci.. Publicado em: 2013-07
-
11. Níveis de contaminantes inorgânicos em cachaças da região do Quadrilátero Ferrífero armazenadas em copos in natura de esteatito (pedra-sabão)
The levels of inorganic contaminants (As, Cd, Cu, Ni and Pb) were measured in 18 Brazilian spirit beverages, before and after 4 contact cycles of 24h each with in natura soapstone (steatite) cups. Results were compared to Brazilian regulation levels. Spirits contained As, Cd, Ni and Pb within permitted levels. For Cu, 5.6% of the brands were above the limit.
Quím. Nova. Publicado em: 2013
-
12. A coexistência de quatro ciclos limite em campos vetoriais seccionalmente lineares em R3 / The coexistence of four limit cycles in piecewise linear vector fields on R3
In this work we study continuous, symmetric and piecewise linear vector fields on R3, we investigate the existence of limit cycles using the closing equations method. More specifically, we study a two parameters family of this vector fields and we show the coexistence of four limit cycles and too, its realization on Chuas circuit.
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/07/2012