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41.
Silva da Costa Russany Pinheiro Wandson Braamcamp de Souza Arruda Mara Silvia Pinheiro Costa Carlos Emmerson Ferreira Converti Attilio Ribeiro Costa Roseane Maria Silva Júnior José Otávio Carrera 《Journal of Thermal Analysis and Calorimetry》2022,147(1):275-284
Journal of Thermal Analysis and Calorimetry - Cupuassu (Theobroma grandiflorum Schum.) is a typical Amazonian fruit, whose seed is used as raw material to produce cupulate. The by-product of its... 相似文献
42.
Carlos E. C. Magalhães Éder C. Lima Francisco J. Krug Marco A. Z. Arruda 《Mikrochimica acta》1999,132(1):95-100
A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described.
Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved
at 105 μm and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only
the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases
and the determinations were carried out in the linear range between 50 and 250 μg L−1. The characteristic mass of aluminium and the detection limit were 45 pg and 2 μg L−1, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n=15) for
repeatability was about 8.2%.
Received December 27, 1998. Revision March 18, 1999. 相似文献
43.
We derive expressions that describe the maximum and minimum envelopes of mode-partition noise converted into intensity noise through an unbalanced interferometer, using a simple model of a multimode laser diode, and experimentally confirm the expressions. 相似文献
44.
Izaura Cirino Nogueira Diógenes Francisco Carlos Nart Mônica B. P. Mello Barreto Marcia Laudelina Arruda Temperini Ícaro de Sousa Moreira 《Journal of Solid State Electrochemistry》2007,11(11):1585-1590
Surface-Enhanced Raman Scattering (SERS) spectra of [Ru(CN)5(pyS)]4− (RupyS) complex self-assembled monolayer (SAM) were obtained on gold and silver surfaces at 632.8 and 413.1 nm excitation
radiations, respectively. The bands assigned to the heme iron of the cytochrome c (cyt c) metalloprotein group were observed
by using the RupyS SAM on silver at 413.1 nm. The Surface-Enhanced Resonance Raman Scattering (SERRS) spectra of the RupyS
SAM on silver in the cyt c solution obtained at −0.2 and +0.2 V present bands at 1,365 and 1,374 cm−1 characteristic of the heme group, indicating the reduced and oxidized states of this protein, respectively. The bands observed
at 1,464, 1,504, and 1,638 cm−1 are used to confirm the redox state of cyt c. The presence of the oxidized and reduced bands in function of different applied
potential is an evidence that the protein is interacting with the modifier.
This paper is dedicated to Prof. Francisco Nart, in memoriam. 相似文献
45.
Thermal stability, thermal decomposition process, residual mass, temperature of glass transition (Tg) and temperature dependence of storage modulus (E’), were determined for latex membranes prepared from six clones of Hevea brasiliensis: IAC 331, IAC 332, IAC 333 and IAC 334 grown at experimental plantations of Instituto Agronômico de Campinas (IAC) in Votuporanga, São Paulo State, Brazil. Latex membranes from GT1 and RRIM 600 Asian matrix clones were used as references. The thermal behavior of latex membranes from genetically improved rubber trees was characterized using thermogravimetry/derivative thermogravimetry (TG/DTG), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The thermal behavior of latex from clones studied in the present work showed similar features of the clones previously reported (IAC 40, IAC 300, IAC 301, IAC 328, IAC 329 and IAC 330), with mass loss in four consecutive steps, except IAC 333, which showed an additional mass loss step. 相似文献
46.
Elisabete A. De Nadai Fernandes Márcio Arruda Bacchi Fábio Sileno Tagliaferro Cláudio Luiz Gonzaga Elvis Joacir De França Paulo Cesar Favaro Adriana de Angelis Fogaça 《Accreditation and quality assurance》2006,10(11):594-598
The introduction of quality systems in laboratories at universities is a difficult task. Test services for external customers are provided to generate additional budget, and there may be a clear awareness about the need for systematic QA/QC actions. However, offering services is not of the highest priority within most university environments. The staff performance is commonly evaluated on basis of published papers and teaching activities, giving little or no weight for the test services. Therefore, implementation of a quality system is often pushed back to a lower priority leading to postponement. The efforts for creating a quality system in a laboratory from a Brazilian university are described in this paper, along with the results produced. 相似文献
47.
KM Clauwaert Van Bocxlaer JF HJ Major JA Claereboudt WE Lambert Van den Eeckhout EM Van Peteghem CH De Leenheer AP 《Rapid communications in mass spectrometry : RCM》1999,13(14):1540-1545
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
48.
Anderson S. Ribeiro Aloísia L. Moretto Marco A. Z. Arruda Solange Cadore 《Mikrochimica acta》2003,141(3-4):149-155
A simple method for the solubilization of powdered milk and soluble coffee using tetramethylammonium hydroxide (TMAH) is
proposed. While 500 μL of the reagent was used for the solubilization of 350 mg of coffee samples, milk samples required 1000 μL
of TMAH. Solubilization at 80 °C takes place within 10, 20 and 30 min for soluble coffee, whole and skim powdered milk, respectively.
Subsequently, the volume was topped up to 25 mL with deionized water. Thereafter, the concentrations of Ca, Cu, Fe, K, Mg,
Mn, Na, P, Se, Sn and Zn were determined by inductively coupled plasma optical emission spectrometry (ICP OES). When applied
to standard reference material and to commercial samples the proposed method showed good results, and it was also compared
with two other preparation methods. Limits of detection calculated for Ca, Cu, Fe, K, Mg, Mn, Na, P, Se, Sn and Zn were 2.1,
0.065, 0.11, 103, 0.088, 0.011, 1.5, 2.1, 1.1, 0.66 and 0.11 μg g−1, respectively. The RSD values were less than 10% for the certified reference materials (IAEA A-11 and BCR 63R). Statistical
tests showed that the results for the metal concentrations do not vary significantly with the different methods or with the
certified reference values, considering a confidence limit of 95%.
Correspondence: Departamento de Química Analítica, Instituto de Química, UNICAMP, 13083-862, Campinas, Brazil. e-mail: codore@igm.unicamp.br
Received August 5, 2002; accepted October 30, 2002 相似文献
49.
Vincent Martin Thibault Le Bourdon José Roberto Arruda 《Journal of sound and vibration》2012,331(15):3493-3508
A large number of inverse problems in acoustics consist of a reverse propagation of the acoustic pressure measured with an array of microphones. The goal is usually to identify the acoustic source location and strength or the surface velocity of a vibrating structure. The quality of the results obtained depends on the propagation model, on the accuracy of the pressure measurements and, finally, on the inverse problem conditioning. How to quantify this quality is the issue addressed in this paper. For this purpose, a geometrical interpretation of the inverse acoustic problem is proposed. The main application will, eventually, be near-field acoustic holography (NAH), but it is expected that the proposed approach will also apply to other types of inverse acoustic problems. First, the geometrical representation of the inverse problem is proposed. The inverse problem is stated from a direct linear problem in the frequency domain. For each frequency, an overdetermined system of linear complex algebraic equations must be inverted. The concept of quality is discussed and a quality index is proposed based upon the residue of the inverse problem, solved in a mean square sense. Then, a simple one-dimensional (plane wave) acoustic example consisting of a source and two pressure measurements is used to illustrate the proposed geometrical representation of the inverse problem and the quality criterion inspired by it. In the simple example, the propagation model can be improved by searching for a reflection coefficient at the origin of the simulated hologram. This reflection coefficient is used to simulate the presence of a hidden source placed behind the source. An artificial attenuation is introduced to simulate the effect of geometrical attenuation present in real NAH problems. Again, using the geometrical representation, it is shown how, from an improved propagation model together with a given measurement noise level in the hologram, one can guarantee a certain quality level of the inverse procedure. Finally, numerical results show, in a preliminary way, how the identified source strength converges towards the exact velocity when the estimated propagation model tends to the exact propagation model. 相似文献
50.
Mónica Alejandra Herrera María Rosende Marco Aurélio Zezzi Arruda Manuel Miró 《Analytica chimica acta》2016
In-vitro physiologically relevant gastrointestinal extraction based on the validated Unified BARGE Method (UBM) is in this work hyphenated to inductively coupled plasma optical emission spectrometry in a batch-flow configuration for real-time monitoring of oral bioaccessibility assays with high temporal resolution. A fully automated flow analyzer is designed to foster in-line filtration of gastrointestinal extracts at predefined times (≤15 min) followed by on-line multi-elemental analysis of bioaccessible micro-nutrients, viz., Cu, Fe and Mn, in well-defined volumes of extracts (300 μL) of transgenic and non-transgenic soybean seeds taken as model samples. 相似文献