76
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Marques T, Scuch F, Baffa O, Nicolucci P. SU-E-T-462: Microscopic Fractions of Dose Enhancement: Size Dependence Study to Gold Nanoparticle Using Monte Carlo. Med Phys 2011. [DOI: 10.1118/1.3612416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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77
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Marques T, Schwarcke M, Garrido C, Zucolot V, Baffa O, Nicolucci P. Gel Dosimetry Analysis of Gold Nanoparticle Application in Kilovoltage Radiation Therapy. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/250/1/012084] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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78
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Paixao FC, Quini CC, Baffa O, Miranda JRDA. A novel device with 36 channels for imaging and signal acquisition of the gastrointestinal tract based on AC biosusceptometry. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:6457-60. [PMID: 21096717 DOI: 10.1109/iembs.2010.5627341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The alternate current biosusceptometry (ACB) is a biomagnetic technique used to study some physiological parameters associated with gastrointestinal (GI) tract. For this purpose it applies an AC magnetic field and measures the response originating from magnetic marks or tracers. This paper presents an equipment based on the ACB which uses anisotropic magnetoresistive (AMR) sensors and an inexpensive electronic support. The ACB-AMR developed consists of a square array of 6×6 sensors arranged in a first-order gradiometer configuration with one reference sensor. The equipment was applied to capture magnetic images of different phantoms and to acquire gastric contraction activity of healthy rats. The results show a reasonable sensitivity and spatial-temporal resolution, so that it may be applied for imaging of phantoms and signal acquisition of the GI tract of small animals.
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79
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Oliveira LC, Kinoshita A, Barreto AMF, Figueiredo AM, Silva JLL, Baffa O. ESR dating of teeth from Brazilian megafauna. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/249/1/012062] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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80
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Corá LA, Américo MF, Oliveira RB, Serra CHR, Baffa O, Evangelista RC, Oliveira GF, Miranda JRA. Biomagnetic Methods: Technologies Applied to Pharmaceutical Research. Pharm Res 2010; 28:438-55. [DOI: 10.1007/s11095-010-0285-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 09/14/2010] [Indexed: 02/06/2023]
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81
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Ereno C, Guimarães SAC, Pasetto S, Herculano RD, Silva CP, Graeff CFO, Tavano O, Baffa O, Kinoshita A. Latex use as an occlusive membrane for guided bone regeneration. J Biomed Mater Res A 2010; 95:932-9. [DOI: 10.1002/jbm.a.32919] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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82
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Marques T, Schwarcke M, Garrido C, Baffa O, Nicolucci P. Benefits of Radiotherapy Added Nanoparticle Assessed by a Quantitative Analysis of Dose-Gradient: An Evaluation in Soft and Lung Tissues by Monte Carlo. Med Phys 2010. [DOI: 10.1118/1.3468350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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83
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Marques T, Schwarcke M, Garrido C, Zucolotto V, Baffa O, Nicolucci P. SU-GG-J-123: Dose Increase in Radiotherapy Evaluated to Biocompatible Levels of Gold Nanoparticle: A Quantitative Analysis by MRI Gel Dosimetry and Monte Carlo Spectrometry. Med Phys 2010. [DOI: 10.1118/1.3468347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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84
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Schwarcke M, Marques T, Nicolucci P, Baffa O. SU-GG-J-120: Silver Nanoparticle Added to Nuclear Medicine: A Preliminary Evaluation of Dose Increase in Iodine Therapy Assessed by Monte Carlo. Med Phys 2010. [DOI: 10.1118/1.3468344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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85
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Bruno AC, Baffa O, Carneiro AO. Hybrid system for magnetic and acoustic measurement. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:761-4. [PMID: 19964487 DOI: 10.1109/iembs.2009.5334067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In order to improve the spatial resolution of Biosusceptometry of Alternate Current (BAC), we are suggesting the coupling of a Doppler ultrasonic transducer with the BAC system. The Doppler transducer obtains information from the vibration of ferromagnetic particles immersed in a visco-elastic medium when it is excited by an alternating magnetic field. In this case, the same magnetic particles used as contrast for susceptometric measurement also will work as contrast for the Doppler measurement. In this work, we present the characterization of the hybrid system for susceptometric and acoustic measurements simultaneously. It was observed that the susceptometric and Doppler ultrasound signal have the same profile and maximum amplitude for frequency of magnetizing field about 200 Hz. When using ferrite particles as magnetic contrast mixed with yogurt as based material, the susceptometric and Doppler measurement have sensitivity for concentration of particles as low as 1%. The sensitivity of the Doppler is dependent of the gradient of magnetic field over the sample. In this work, the magnetic field 5 cm far from the face of the transducer was 70 microT/volts.
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86
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Oliveira LC, Kinoshita A, Lopes RP, Baffa O. A new method for calculating the accumulated dose in ESR dating and retrospective dosimetry. HEALTH PHYSICS 2010; 98:427-431. [PMID: 20065716 DOI: 10.1097/01.hp.0000348463.28658.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dose evaluation by electron spin resonance (ESR) is usually accomplished by constructing a dose-response curve by measuring the peak-to-peak intensity of the dosimetric signals in the g = 2 region. In several cases, this signal is overlapped with others that can interfere with dose reconstruction. In this work a new method to correct the spectrum before the measurement of the signal intensity is proposed. Examples of dose determination of accumulated dose (AD) of two fossil teeth from southern Brazilian megafauna are given. One of them presents a dose-independent signal in the region of interest, and the validity of this method is shown. For the other, without interfering signals, no difference in the AD was found. This method can also be applied to retrospective dosimetry by ESR for any sample with dose-independent interfering signals, thus improving the accuracy in AD determination by ESR.
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87
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Kinoshita A, José FA, Baffa O. An attempt to use sweeteners as a material for accident dosimetry. HEALTH PHYSICS 2010; 98:406-411. [PMID: 20065713 DOI: 10.1097/01.hp.0000348017.54094.73] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In case of a radiological accident, it is important to determine the exposure to radiation of the general population. Several materials can be used to reconstruct the exposed dose. Tooth enamel has been studied for a long time, and now the procedures to determine the dose are well established for in vitro measurements. Many materials have been investigated by different techniques: sugar, wall bricks, roof tiles, plastics, watch glass, ruby present in watches, medicines carried by persons and shell button, among others. In this work an attempt is made to use sweeteners as a possible accident dosimeter material because they are becoming increasingly common. Sweeteners based on saccharine, cyclamate, stevia, and aspartame were acquired in local stores, and ESR spectrum was recorded before and after gamma irradiation. Spectrum simulation demonstrated that there are two main radicals with g = 2.0063, A = 1.6 mT, and g = 2.0048, A = 5 mT due to lactose. For the better characterization of spectroscopic and dosimetric properties of these materials, higher microwave frequency (K-band, nu approximately 24 GHz) was also employed. Experiments in X-band (nu approximately 9 GHz) showed that low dose levels of 500 mGy can be measured with this material, demonstrating the potential use of sweeteners for retrospective dosimetry.
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88
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Chen F, Ramirez JV, Nicolucci P, Baffa O. Sensitivity comparison of two L-alanine doped blends to different photon energies. HEALTH PHYSICS 2010; 98:383-387. [PMID: 20065709 DOI: 10.1097/01.hp.0000348003.11889.68] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Blends of L-alanine (85% weight proportion) with KI (10%) and with PbI2 (10%), these last two compounds acting as dopants, and with PVA (5%) acting as binder, were prepared in water at 80 degrees C. A blend of pure L-alanine (95%) with PVA (5%) was also prepared. The three blends were irradiated with photon beams of different energies (120 kV, Co, and 10 MV) to a unique dose of 30 Gy to compare their sensitivities for those three energies. EPR spectra of the three irradiated blends were recorded in a K-Band spectrometer (24 GHz) taking aliquots of about 4 mg for each blend. The energy sensitivity of a blend was defined as the peak-to-peak amplitude of its EPR spectrum central line. For the Co energy (1.25 MeV) the blends presented practically the same sensitivity, indicating that the presence of the dopants does not affect the sensitivity of L-alanine. For 10 MV x-rays, there was an increment (around 10%-20%) in sensitivity for the two L-alanine doped blends compared with the pure L-alanine blend (not doped). In the case of 120 kV x-rays, the blends ala+KI and ala+PbI showed increments of 10 and 20 times more sensitivity than the pure L-alanine blend. It is concluded that the dopants KI and PbI2 produce a great enhancement of the L-alanine sensitivity to low-energy photons. For the same dopant's content (10%) in the blend, PbI2 showed a better performance. Increasing the PbI2 proportion (30%) in the blend allows the detection of radiation dose as low as 10 mGy for 120 kV x-rays. These results encourage the authors to try to enhance the sensitivity of L-alanine even more by increasing the dopant's content in the blend and diminishing the lower limit detection. Application of these L-alanine doped blends in the dosimetry in diagnostic radiology could be possible.
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89
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Tedeschi W, Müller HP, Ludolph A, Kraft H, de Araujo D, Neves U, Baffa O, Erné S. A NEW METHOD FOR THE ANALYSIS OF FUNCTIONAL MAGNETIC RESONANCE IMAGING DATA: MUTUAL INFORMATION TESTS. ACTA ACUST UNITED AC 2009. [DOI: 10.1515/bmte.2003.48.s1.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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90
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Fernandes JP, Pastorello BF, Araújo DBD, Baffa O. Formaldehyde increases MAGIC gel dosimeter melting point and sensitivity. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/164/1/012004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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91
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Pianoschi T, Marques T, Baffa O, Nicolucci P. SU-FF-I-163: Study of Dosimetric Characteristics of MAGIC Polymer Gel with Formaldehyde for Electrons Beams Using PENELOPE Code. Med Phys 2009. [DOI: 10.1118/1.3181284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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92
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Marques T, Schwarcke M, Alva-Sánchez M, Baffa O, Nicolucci P. SU-FF-J-149: Monte Carlo Simulation of Dose Distribution Around 198 Au Nanoparticles: A Preliminary Study for Treatment Quality Criterion. Med Phys 2009. [DOI: 10.1118/1.3181441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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93
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Carneiro AO, Baffa O, Silva GT, Fatemi M. Vibro-magnetometry: theoretical aspects and simulations. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2009; 56:1065-1073. [PMID: 19473925 DOI: 10.1109/tuffc.2009.1140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this article, we introduce the theory for vibro-magnetometry (VM) with computational simulations for an idealized experimental setup. A method based on acoustic radiation force and magnetic measurement has been proposed for interrogating the mechanical vibrations of a target immersed in fluid medium. In this method, ultrasound radiation is used to exert a low-frequency (in kHz range) force on a rigid magnetized target immersed in a viscoelastic medium. In response, the target vibrates sinusoidally in a pattern determined by viscoelastic properties of the medium. The magnetic field resulting from target vibration is related to both the ultrasonic and low-frequency (kHz range) mechanical characteristics of the medium. We report the relationship between the magnetic field signal and the incident ultrasonic pressure field in terms of the mechanical parameters of the medium. Simulations were conducted to demonstrate a simple approach based on using amplitude-modulated ultrasound to generate a dynamic acoustic radiation force on a magnetic target. The magnetic field generated by vibration of this target is then obtained and used to estimate the radiation-force-induced displacement as a function of time. It was observed that the intensity of the dynamic component of the magnetic field caused by the acoustic excitation is high enough to be registered by a conventional magnetic sensor. When a low stress is applied on a reactive magnetic target embedded in the medium, the subsequent oscillating magnetic field is measured by a dedicated magnetic sensor, yielding the applicable mechanical information of the host medium. The proposed methodology presents a powerful tool for evaluation of acoustic radiation force as well as the mechanical properties of soft materials.
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94
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Santos ABD, Silva DHS, Bolzani VDS, Santos LÁ, Schmidt TM, Baffa O. Antioxidant properties of plant extracts: an EPR and DFT comparative study of the reaction with DPPH, TEMPOL and spin trap DMPO. J BRAZIL CHEM SOC 2009. [DOI: 10.1590/s0103-50532009000800015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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95
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Sturzbecher MJ, Tedeschi W, Cabella BCT, Baffa O, Neves UPC, de Araujo DB. Non-extensive entropy and the extraction of BOLD spatial information in event-related functional MRI. Phys Med Biol 2008; 54:161-74. [PMID: 19075356 DOI: 10.1088/0031-9155/54/1/011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Functional magnetic resonance imaging (fMRI) data analysis has been carried out recently in the framework of information theory, by means of the Shannon entropy. As a natural extension, a method based on the generalized Tsallis entropy was developed to the analysis event-related (ER-fMRI), where a brief stimulus is presented, followed by a long period of rest. The new technique aims for spatial localization neuronal activity due to a specific task. This method does not require a priori hypothesis of the hemodynamic response function (HRF) shape and the linear relation between BOLD responses with the presented task. Numerical simulations were performed so as to determine the optimal values of the Tsallis q parameter and the number of levels, L. In order to avoid undesirable divergences of the Tsallis entropy, only positive q values were studied. Results from simulated data (with L = 3) indicated that, for q = 0.8, the active brain areas are detected with the highest performance. Moreover, the method was tested for an in vivo experiment and demonstrated the ability to discriminate active brain regions that selectively responded to a bilateral motor task.
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96
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Angulo IL, Covas DT, Carneiro AA, Baffa O, Elias Junior J, Vilela G. Determination of iron-overload in thalassemia by hepatic MRI and ferritin. Rev Bras Hematol Hemoter 2008. [DOI: 10.1590/s1516-84842008000600006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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97
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Andreis U, Américo MF, Corá LA, Oliveira RB, Baffa O, Miranda JRA. Gastric motility evaluated by electrogastrography and alternating current biosusceptometry in dogs. Physiol Meas 2008; 29:1023-31. [PMID: 18698113 DOI: 10.1088/0967-3334/29/9/002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Association techniques could be the answer for evaluating electromechanical coupling and gastric emptying under basal conditions and after administration of drugs. Electrogastrography (EGG) and alternating current biosusceptometry (ACB) emerged due to their interesting nature, noninvasiveness and low cost. The aims were to examine in dogs the effect of erythromycin on gastric emptying by ACB and electrical and motor responses to erythromycin and propranolol by ACB and EGG respectively. Twelve beagle dogs ingested a solid test meal on separate days. Under anesthesia, gastric motility was evaluated by EGG and ACB after erythromycin and propranolol administration. Without anesthesia, gastric emptying was assessed under basal conditions and after erythromycin by ACB. ACB and EGG showed a strong temporal correlation. Erythromycin and propranolol presented the same profile with different power ratios; the amplitude increased whereas frequency decreased. Also, erythromycin administration hastened gastric emptying while reducing the orocaecal transit time. There is a demand for reliable, easy-to-perform and comfortable techniques to record gastric emptying and gastric activity in medicine and veterinary practice. In summary, the association of ACB with EGG accompanied by an appropriate animal model is promising for evaluating effects of drugs in gastric myoelectrical and contractile activity.
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98
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Angulo IL, Carneiro AA, Baffa O, Covas DT. Susceptometric avaliation of chelation with deferoxamine. Rev Bras Hematol Hemoter 2008. [DOI: 10.1590/s1516-84842008000400019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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99
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Paixão FC, Silva FM, Miranda JRDA, Baffa O. Magnetoresistive sensors in a new biomagnetic instrumentation for applications in gastroenterology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2008; 2007:2948-51. [PMID: 18002613 DOI: 10.1109/iembs.2007.4352947] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Anisotropic Magnetoresistive (AMR) sensors shows a new possibility to detect magnetic fields produced by magnetic particles present in the gastrointestinal (GI) tract. A system that uses excitation and detection of magnetic field was developed using AMR sensor. A magnetic flux concentrator was also studied to increase the sensitivity of AMR in this work.
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100
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Cano ME, Castañeda-Priego R, Gil-Villegas A, Sosa MA, Schio P, de Oliveira AJA, Chen F, Baffa O, Graeff CFO. Magnetic Properties of Synthetic Eumelanin—Preliminary Results. Photochem Photobiol 2008; 84:627-31. [DOI: 10.1111/j.1751-1097.2008.00302.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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