Repositório Institucional - Unifesp :: Navegando por Palavras-chave "Spectroscopy"

Navegando por Palavras-chave "Spectroscopy"

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Acesso aberto (Open Access)
Aplicação de um protocolo de espectroscopia por ressonância magnética das adrenais: experiência com mais de 100 casos
(Colégio Brasileiro de Radiologia e Diagnóstico por Imagem, 2014-12-01) Melo, Homero José de Farias e [UNIFESP]; Goldman, Suzan M.; Szejnfeld, Jacob [UNIFESP]; Faria, Juliano F.; Huayllas, Martha K. P.; Andreoni, Cássio [UNIFESP]; Kater, Claudio Elias [UNIFESP]; Centro Universitário São Camilo; Universidade Federal de São Paulo (UNIFESP)
Objective: To evaluate a protocol for two-dimensional (2D) hydrogen proton (1H) magnetic resonance spectroscopy (MRS) (Siemens Medical Systems; Erlangen, Germany) in the detection of adrenal nodules and differentiation between benign and malignant masses (adenomas, pheochromocytomas, carcinomas and metastases). Materials and Methods: A total of 118 patients (36 men; 82 women) (mean age: 57.3 ± 13.3 years) presenting with 138 adrenal nodules/masses were prospectively assessed. A multivoxel system was utilized with a 2D point-resolved spectroscopy/chemical shift imaging sequence. The following ratios were calculated: choline (Cho)/creatine (Cr), 4.0–4.3/Cr, lipid (Lip)/Cr, Cho/Lip and lactate (Lac)/Cr. Results: 2D-1H-MRS was successful in 123 (89.13%) lesions. Sensitivity and specificity values observed for the ratios and cutoff points were the following: Cho/Cr ≥ 1.2, 100% sensitivity, 98.2% specificity (differences between adenomas/pheochromocytomas and carcinomas/ metastases); 4.0–4.3 ppm/Cr ≥ 1.5, 92.3% sensitivity, 96.9% specificity (differences between carcinomas/pheochromocytomas and adenomas/metastases); Lac/Cr ≤ –7.449, 90.9% sensitivity and 77.8% specificity (differences between pheochromocytomas and carcinomas/adenomas). Conclusion: Information provided by 2D-1H-MRS were effective and allowed for the differentiation between adrenal masses and nodules in most cases of lesions with > 1.0 cm in diameter.
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Applicability of ft-ir techniques and goniometry on characterization of carbon fiber surfaces
(Inst aeronautica & espaco-iae, 2016) Oliveira Junior, Mauro Santos [UNIFESP]; Diniz, Milton Faria; Lazzarini Dutra, Rita de Cassia; Massi, Marcos; Otani, Choyu
Carbon fibers have been widely used as structural reinforcement in aeronautical composites, because of their exceptional mechanical properties. However, carbon fibers present few polar groups on their surfaces inducing a weak interaction with some thermosetting and thermoplastic matrices. Surface treatments, such as thermal and electrochemical oxidation, are generally followed by sizing in order to improve interfacial adhesion between carbon fibers and some matrices. The precise surface characterization, by means of its chemical groups and radical identification, has been pointed out as an effective tool of carbon fibers finishing assessment process. Goniometry and Fourier transform-infrared spectroscopy are widely used to characterize some materials applied in industry, but not for carbon fibers, mainly because of their filamentary shape and the high concentration of carbon even in their near surface. In this paper, unsized and sized Torayca T300 carbon fibers were characterized by goniometry tests to evaluate hydrophilic or hydrophobic character. Qualitatively, it was noticed the effect of sizing on carbon fibers by their hydrophilic behavior, which has not been observed in unsized samples. Chemical analysis was performed by Fourier transform-infrared spectroscopy using different setups: photoacoustic, attenuated total reflectance and universal attenuated total reflectance. The Fourier transform-infrared spectroscopy/attenuated total reflectance/Germanium was shown to be the most promising technique to analyze carbon fibers surface, despite the low level of relative intensities of some bands. By this technique, it was possible to observe differences between unsized and sized carbon fibers spectra.
Acesso aberto (Open Access)
Avaliação do efeito da interação entre o íon metálico Cu (II) e o pesticida malathion em amostras de solo
(Universidade Federal de São Paulo, 2021-12-17) Lima, Ana Layla Carvalho de [UNIFESP]; Akamatu, Eliana Maíra Agostini Valle [UNIFESP]; http://lattes.cnpq.br/1501926375630837; http://lattes.cnpq.br/0527284336985558
Com a utilização sem fiscalizaçao de diversos pesticidas no meio ambiente devido a sua eficiência no tratamento de pestes em pequena e larga escala, estas substâncias acabam se tornando um grande motivo de preocupação ao solo e água. Sabe-se que suas moléculas apresentam grupos funcionais que podem interagir com íons metálicos, formando novos compostos no meio ambiente e alterando suas características, propriedades e biodisponibilidade no ambiente. Dessa forma, o intuito deste trabalho foi estudar a interação entre o pesticida malathion e o íon metálico cobre (II) em amostras de solo. Para este fim, foram utilizados técnicas eletroanalíticas e espectroscópicas.Inicialmente foi realizado um estudo do comportamento eletroquímico das espécies por meio da técnica de voltametria, onde foi observada a interação entre as duas espécies através do deslocamento de seus potenciais de oxidação e redução, confirmada pela técnica de espectroscopia UV-Vis. Posteriormente o efeito dessa complexação foi avaliado em amostras de solo, que foram digeridas por digestão ácida sob refluxo, seguida da determinação do teor de cobre total nas amostras com e sem a adição do pesticida por espectrometria de absorção atômica com chama. Com esta metodologia empregada, não foi possível verificar a interação entre as espécies, indicando que o cobre pode não estar disponível para interagir com o pesticida no meio, uma vez que pode estar complexado com a matéria orgânica do solo, formando uma espécie altamente estável nas condições do meio.
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Chemical abundance analysis of the Be star HD 171054
(Elsevier B.V., 2011-08-01) Levenhagen, R. S. [UNIFESP]; Kuenzel, R.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
In this work the results of a spectroscopic study of the southern field narrow-line Be star HD 171054 are presented. High dispersion and signal-to-noise ratio spectra allowed the estimation of the fundamental photospheric parameters such as the projected rotational velocity, effective temperature and superficial gravity from non-LTE stellar atmosphere models. From these parameters and microturbulence, the abundances of He, C, N, O, Mg, Al and Si for this object are estimated. Results show that C is depleted whereas N is overabundant compared with the sun and OB stars in the solar vicinity. Oxygen and helium are close to the solar value. Magnesium is down by 0.43 dex and aluminium and silicon are overabundant. (C) 2010 Elsevier B.V. All rights reserved.
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Consensus Paper: Radiological Biomarkers of Cerebellar Diseases
(Springer, 2015-04-01) Baldarcara, Leonardo [UNIFESP]; Currie, Stuart; Hadjivassiliou, M.; Hoggard, Nigel; Jack, Allison; Jackowski, Andrea P. [UNIFESP]; Mascalchi, Mario; Parazzini, Cecilia; Reetz, Kathrin; Righini, Andrea; Schulz, Joerg B.; Vella, Alessandra; Webb, Sara Jane; Habas, Christophe; Fed Univ Tocantins; Universidade Federal de São Paulo (UNIFESP); Univ Sheffield; Royal Hallamshire Hosp; Yale Univ; Univ Florence; Meyer Children & Careggi Hosp Florence; Childrens Hosp Buzzi; RWTH Aachen Univ Hosp; Forschungszentrum Julich; Julich Aachen Res Alliance JARA; Univ Hosp Siena; Univ Washington; CHNO Quinze Vingts
Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. in the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine.
Acesso aberto (Open Access)
Efeito do treinamento com neurofeedback por espectroscopia infravermelha sobre o desempenho cognitivo mensurável em sujeitos saudáveis: um estudo piloto
(Universidade Federal de São Paulo (UNIFESP), 2016-04-28) Ducos, Daniella Valverde [UNIFESP]; Dias, Alvaro Machado [UNIFESP]; http://lattes.cnpq.br/0494751833227700; http://lattes.cnpq.br/1889400048554491; Universidade Federal de São Paulo (UNIFESP)
Objective: The primary objective of this study was to investigate the effect of a hemoencephalographic neurofeedback training (HEG-nf) protocol, a technique based on operant conditioning by use of infrared spectroscopy, over the cognitive performance of healthy young adults. Methods: Twelve individuals were selected and enrolled in training for 10 sessions, twice a week. Training was adjusted so that subjects received visual and auditory feedback whenever they increased cerebral blood flow in relation to a baseline that was defined by the mean blood perfusion level measured during the session?s 10 initial seconds. Sensor was positioned alternately on F7, Fp1, Fp2 and F8 sites, according to the 10-20 system. Neuropsychological data were collected from subjects with a comprehensive battery of tests at baseline (T1), and again by the end of HEG-nf (T2) and 3-month follow-up (T3). Results: The Linear Mixed Model showed evidence that participants achieved a significant improvement on measures of inhibitory control, sustained attention and visuospatial learning from T1 to T2, which were maintained between T1 and T3. Performance improvement on working memory and speed of information processing tasks was significant from T1 to T2. Performance on cognitive flexibility tasks showed inconclusive results. The variable reflecting gain on cerebral oxygen saturation as a training effect evidenced an unsteady but positive result by the end of training protocol. Conclusion: Results showed that this intervention optimizes cognitive abilities, especially those related to executive functioning, in healthy young adults. Cognitive enhancement seems to be related to the capacity of increasing cerebral oxygen saturation in prefrontal cortex by HEG-nf.
Acesso aberto (Open Access)
Estudo da interação entre o fungicida thiram e íons ferro (III)
(Universidade Federal de São Paulo, 2022-11-23) Pracchia, Maria Luisa [UNIFESP]; Akamatu, Eliana Maíra Agostini Valle [UNIFESP]; Silva, Heron Dominguez Torres da [UNIFESP]; http://lattes.cnpq.br/1501926375630837
Os agrotóxicos são compostos orgânicos amplamente utilizados desde a década de 60 para conter a proliferação de pragas e propiciar o crescimento das culturas agrícolas. O amplo uso desses compostos no Brasil traz à tona questões sobre seu comportamento no ambiente. Os ditiocarbamatos são um grupo de fungicidas amplamente utilizados no Brasil, devido aos seus altos índices de eficiência e baixo custo, esse grupo apresenta em sua composição átomos de enxofre capazes de atuar como ligantes frente a íons metálicos. O thiram é um dos cinco fungicidas da família dos ditiocarbamatos permitidos para uso nas lavouras brasileiras. Dentre os metais passíveis de atuar como centros metálicos em compostos de coordenação está o ferro, muito disponível em território brasileiro. Nesse trabalho avaliou-se interação entre o íon metálico ferro (III) e o fungicida thiram em duas soluções de pH distintos, ácido e neutro, por meio da espectroscopia de UV-Vis e voltametria cíclica. Um planejamento experimental fatorial foi utilizado para a otimização dos experimentos, os fatores escolhidos foram pH e proporção metal ligante, em dois níveis: um alto e um baixo. Foi possível observar no espectro de UV-Vis a presença de duas bandas do thiram, contidas em 215 nm e 270 nm em meio aquoso e 212 nm e 270 nm em meio ácido. As absortividades molares da banda em 270nm do thiram diminuíram de 19151,67 L cm-1. mol-1 na solução de pH neutro para 6843,59 L cm-1 . mol-1 na solução de pH ácido estudada. A presença do metal causou um efeito hipercrômico nas bandas do thiram em ambos os valores de pH sendo o efeito mais intenso na solução de pH ácido. Não foi observado o surgimento de novas bandas com as adições de ferro. Nas análises de voltametria cíclica do íon ferro na solução de pH neutro foi possível observar o pico redução em -0,04 V e as adições de thiram resultaram em deslocamentos do potencial de pico para -0,03V e -0,01 V. Na solução de pH ácido o pico de redução do metal foi observado –0,3V, as adições de thiram resultaram em deslocamentos para -0,33V e –0,34V. As superfícies de resposta foram obtidas para ambas as análises. Para as análises espectroscópicas a absorbância da banda do thiram após as adições de ferro foi adotada como resposta e para as análises eletroquímicas adotou-se como resposta a variação no potencial da redução do metal com a adição do fungicida. O modelo matemático que melhor se adequou a ambas as superfícies foi o 2-way-interaction, o gráfico de pareto demonstrou que o fator proporção altera significativamente ambas as respostas e pH não é um fator significante para a resposta eletroquímica. Após a síntese os espectros de infravermelho e Raman demonstraram que não houve a formação de ligações entre o thiram e o íon Fe (III) uma vez que não foram observadas diferenças significativas entre os espectros dos reagentes e do produto obtido pela síntese.
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Image evaluation of HIV encephalopathy: a multimodal approach using quantitative MR techniques
(Springer, 2011-11-01) Prado, Paulo T. C.; Escorsi-Rosset, Sara; Cervi, Maria C.; Santos, Antonio Carlos; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
Introduction A multimodal approach of the human immunodeficiency virus (HIV) encephalopathy using quantitative magnetic resonance (MR) techniques can demonstrate brain changes not detectable only with conventional magnetic resonance imaging (MRI). the aim of this study was to compare conventional MRI and MR quantitative techniques, such as magnetic resonance spectroscopy (MRS) and relaxometry and to determine whether quantitative techniques are more sensitive than conventional imaging for brain changes caused by HIV infection.Methods We studied prospectively nine HIV positive children (mean age 6 years, from 5 to 8 years old) and nine controls (mean age 7.3 years; from 3 to 10 years), using MRS and relaxometry. Examinations were carried on 1.5-T equipment.Results HIV-positive patients presented with only minor findings and all control patients had normal conventional MR findings. MRS findings showed an increase in choline to creatine (CHO/CRE) ratios bilaterally in both frontal gray and white matter, in the left parietal white matter, and in total CHO/CRE ratio. in contrast, N-acetylaspartate to creatine (NAA/CRE) ratios did not present with any significant difference between both groups. Relaxometry showed significant bilateral abnormalities, with lengthening of the relaxation time in HIV positive in many regions.Conclusion Conventional MRI is not sensitive for early brain changes caused by HIV infection. Quantitative techniques such as MRS and relaxometry appear as valuable tools in the diagnosis of these early changes. Therefore, a multimodal quantitative study can be useful in demonstrating and understanding the physiopathology of the disease.
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Intrinsic Fluorescence of Protoporphyrin IX from Blood Samples Can Yield Information on the Growth of Prostate Tumours
(Springer, 2010-11-01) Silva, Flávia Rodrigues de Oliveira [UNIFESP]; Helena Bellini, Maria [UNIFESP]; Regina Tristao, Vivian [UNIFESP]; Schor, Nestor [UNIFESP]; Vieira, Nilson Dias; Courrol, Lilia Coronato [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); IPEN CNEN SP
Prostate cancer is one of the most common types of cancer in men, and unfortunately many prostate tumours remain asymptomatic until they reach advanced stages. Diagnosis is typically performed through Prostate-Specific Antigen (PSA) quantification, Digital Rectal Examination (DRE) and Transrectal Ultrasonography (TU). the antigen (PSA) is secreted by all prostatic epithelial cells and not exclusively by cancerous ones, so its concentration also increases in the presence of other prostatic diseases. DRE and TU are not reliable for early detection, when histological analysis of prostate tissue obtained from a biopsy is necessary. in this context, fluorescence techniques are very important for the diagnosis of cancer. in this paper we explore the potential of using endogenous phorphyrin blood fluorescence as tumour marker for prostate cancer. Substances such as porphyrin derivatives accumulate substantially more in tumours than in normal tissues; thus, measuring blood porphyrin concentration by autofluorescence intensity may provide a good parameter for determining tumour stage. in this study, the autofluorescence of blood porphyrin was analyzed using fluorescence and excitation spectroscopy on healthy male NUDE mice and in those with prostate cancer induced by inoculation of DU145 cells. A significant contrast between the blood of normal and cancer subjects could be established. Blood porphyrin fluorophore showed an enhancement on the fluorescence band around 632 nm following tumour growth. Fluorescence detection has advantages over other light-based investigation methods: high sensitivity, high speed and safety. However it does carry the drawback of low specificity of detection. the extraction of blood porphyrin using acetone can solve this problem, since optical excitation of further molecular species can be excluded, and light scattering from blood samples is negligible.
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Kinematics and chemical abundances of the B star HD 28248
(Elsevier B.V., 2013-07-01) Levenhagen, R. S. [UNIFESP]; Kuenzel, R.; Leister, N. V.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
We perform a detailed elemental abundance study of the early-type B star HD 28248 and estimate its orbital path in the Galaxy. From the comparison of spectroscopic observations performed at the European Southern Observatory at La Silla in 2001/Oct/07 with non-LTE synthetic spectra using a new wrapper for the simultaneous fitting of several lines of a given atomic species, the abundances of He, C, N, O, Mg, Al, Si, P, S, Ar and Fe were determined for the first time. the radial velocity of HD 28248 has been also estimated from the positions of centroids of nine neutral helium lines and Mg II lambda 4481 angstrom, allowing to calculate its right-handed Galactic space-velocity components U, V and W and estimate its orbital path in the Galaxy for the first time. Our chemical analysis depicted an outstanding enrichment of several atomic species, particularly [Fe/H] = +0.25 dex and [O/Fe] = +0.32 dex. the kinematic parameters show that its orbit is confined to the galactic disk with a scale height of 400 pc and the star has moved about 4 kpc from its birthplace to the current position. the elemental abundances do not follow the predicted [Fe/H] and [O/Fe] gradients currently established for the Galaxy. A hypothetical scenario for the contamination could be the mass transfer in a binary system during previous evolutionary phases. (C) 2012 Elsevier B.V. All rights reserved.
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Millisecond direct measurement of the magnetocaloric effect of a fe2p-based compound by the mirage effect
(Univ Brasilia, 2016) Cugini, F.; Porcari, G.; Viappiani, C.; Caron, L.; dos Santos, A. O.; Cardoso, L. P.; Passamani, E. C.; Proveti, J. R. C.; Gama, Sergio [UNIFESP]; Bruck, E.; Solzi, M.
We present direct measurements of the magnetocaloric effect on a Fe2P-based compound induced by a milliseconds pulsed magnetic field of 1 T to test their possible use in high frequency (up to 100 Hz) thermomagnetic cycles. The reported measurements were performed with an innovative and versatile non-contact set up based on the mirage effect. The adiabatic temperature change of a MnFeP0.45As0.55 sample is presented and compared with measurements performed varying the same magnetic field in a time interval of 1 s and 100 ms. These results demonstrate the absence of kinetic constraints in the first-order phase transition of this sample induced on the milliseconds time scale. The study of the materials' response to millisecond magnetic field pulses represents a fundamental test for the development of more powerful and efficient magnetic refrigerators. (C) 2016 AIP Publishing LLC.
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Nearest-neighbor nitrogen and oxygen distances in the iron(II)-DNA complex studied by extended X-ray absorption fine structure
(Elsevier B.V., 2010-11-01) Bertoncini, Clelia R. A. [UNIFESP]; Meneghini, Rogerio [UNIFESP]; Tolentino, Helio; Universidade Federal de São Paulo (UNIFESP); LNLS
In mammalian cells, DNA-bound Fe(II) reacts with H(2)O(2) producing the highly reactive hydroxyl radical ((center dot)OH) in situ. Since (center dot)OH attacks nearby DNA residue generating oxidative DNA damage, many questions have arisen regarding iron-DNA complex formations and their implication in pre-malignant mutations and aging. in this work, a solid sample of Fe(II)-DNA complex containing one Fe(II) per 10 nucleotides was analyzed from extended X-ray absorption fine structure (EXAFS) spectra collected in a synchrotron radiation light source. Best fitting parameters of the EXAFS signal for the first two shells provide evidence of five oxygen atoms at 1.99 +/- 0.02 angstrom and one nitrogen atom at 2.20 +/- 0.02 angstrom in the inner coordination sphere of the Fe(II)-DNA complex. Considering that both purine base moieties bearing nitrogen atoms are prone to chelate iron, these results are consistent with the previously observed lower levels of DNA damage in cytosine nucleotides relative to adenine and guanine sites in cells under more physiological conditions of Fe(II) Fenton reaction. (C) 2010 Elsevier B.V. All rights reserved.
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Optical Properties of Metacycline, Oxytetracycline and Chlortetracycline Europium Complexes in the Presence of Hydrogen Peroxide
(Springer, 2009-07-01) Grasso, Andrea Nastri; Teixeira, Luciane dos Santos; Vieira, Nilson Dias; Courrol, Lilia Coronato [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); IPEN CNEN SP
Tetracycline possesses a great tendency to form complexes with a number of chemical species, particularly with Eu(3+) ions. in this work we investigate the europium optical properties of three tetracyclines europium complexes: Metacycline (MTc), Oxytetracycline (OTc), and Chlortetracycline (CTc), in the presence and absence of hydrogen peroxide (HP). the results show that the emission band of EuOTc have enhancement in the presence of hydrogen peroxide. A calibration curve was shown for this complex with the best molar ratio obtained.
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Physical parameters and chemical abundances of delta Ceti
(Elsevier B.V., 2013-01-01) Levenhagen, R. S. [UNIFESP]; Kuenzel, R.; Leister, N. V.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
A detailed spectroscopic study of a beta Cephei variable star, delta Ceti, is presented. Physical fundamental parameters are estimated from the best fitting of 26 neutral helium lines and Balmer profiles: effective temperature, superficial gravity and projected rotation velocity. Non-LTE abundances of He, C, N, O, Ne, Mg, Al, Si, P. S. Ar and Fe are achieved using model atmospheres with updated atomic data. Our analysis show an N-enrichment and Fe overabundance, with [O/Fe]congruent to -0.73 dex, confirming this object to be a metal-rich star, which is a requirement for the kappa-mechanism to trigger the pulsations observed in beta Cephei stars. (C) 2012 Elsevier B.V. All rights reserved.

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