Helio Amorim - Academia.edu (original) (raw)
Papers by Helio Amorim
Caderno Brasileiro de Ensino de Física
Neste trabalho apresentamos um projeto de construção de um marégrafo baseado num telêmetro ultras... more Neste trabalho apresentamos um projeto de construção de um marégrafo baseado num telêmetro ultrassônico controlado por uma placa Arduino Uno. O projeto é de fácil construção e de baixo custo e tem por objetivo viabilizar o estudo do fenômeno das marés oceânicas integrando atividades investigativas com a prática experimental. O fenômeno das marés se mostra uma excelente oportunidade para o estudo da gravitação universal de Isaac Newton e do estudo do movimento orbital do sistema Terra – Lua – Sol, dos quais é um resultado direto. Neste artigo, focalizamos basicamente a montagem experimental e apresentamos alguns resultados preliminares. Reservamos para um próximo artigo sugestões de aplicações em eventos investigativos bem definidos envolvendo o modelo newtoniano para o fenômeno das marés.
Origins Life Evol Biosphere, 1995
Revista Brasileira de Ensino de Física, 2015
Neste trabalho apresentamos uma experiência simples de condução térmica usando sensores de temper... more Neste trabalho apresentamos uma experiência simples de condução térmica usando sensores de temperatura digitais com tecnologia one-wire(um-fio) associados a uma placa Arduino para controle e aquisição de dados. Os sensores utilizados são acessóveis e podem ser facilmente encontrados no mercado nacional. O modelo experimental reproduz uma experiência clássica de condução térmica usada comumente em livros didáticos de física para apresentar e discutir a lei de Fourier da condução térmica. Os resultados se mostraram suficientemente sensíveis para revelar uma distribuição não linear de temperaturas numa situação em que condições de contorno pouco realistas, e comumente aplicadas à lei de Fourier nos livros didáticos, resulta num comportamento linear.
CrystEngComm, 2015
The structure of a magnetic two-dimensional CuII–MnII heterometallic coordination polymer was sol... more The structure of a magnetic two-dimensional CuII–MnII heterometallic coordination polymer was solved by using synchrotron X-ray powder diffraction.
Revista Brasileira de Ensino de Física, 2014
Apresentamos uma montagem experimental simples para o estudo da maré atmosférica, baseada no uso ... more Apresentamos uma montagem experimental simples para o estudo da maré atmosférica, baseada no uso da placa Arduino Uno. Com essa montagem, o professor de física no Ensino Médio poderá apresentar para seus alunos as oscilações barométricas, um efeito fundamentalmente de origem térmica devido ao aquecimento da atmosfera produzido pela radiação solar. Apresentamos também uma comparação entre a maré atmosférica e o efeito gravitacional da maré oceânica, destacando as diferenças entre os dois fenômenos.
The structure of ammonium azide (N H 4) N 3was (re-)dete r - minated ab initi ofrom x-ray powder ... more The structure of ammonium azide (N H 4) N 3was (re-)dete r - minated ab initi ofrom x-ray powder diffraction experiment usin g synchrotron radiation. We tried to detail and comment the differen t steps involved in the structure determination. The compound cryst a - llize in the orthorhombic Pmna space group (no.53) with a= 8.937(1 ) Å, b= 3.8070(5)
Cellular Origin and Life in Extreme Habitats and Astrobiology, 2004
ADSORPTION AND CATALYSIS OF NUCLEOTIDE HYDROLYSIS BY PYRITE IN MEDIA SIMULATING PRIMEVAL AQUEOUS ... more ADSORPTION AND CATALYSIS OF NUCLEOTIDE HYDROLYSIS BY PYRITE IN MEDIA SIMULATING PRIMEVAL AQUEOUS ENVIRONMENTS ADALBERTO VIEYRA1, ANA ... in artificial seawater promotes breakdown of the (3, 7-and the a,(}-phosphoanhydride bond of ATP ...
Revista Brasileira de Ensino de Física, 2011
Neste trabalho, apresentamos a placa Arduino como uma opção de muito baixo custo para a aquisição... more Neste trabalho, apresentamos a placa Arduino como uma opção de muito baixo custo para a aquisição de dados com um PC. Duas aplicações simples que mostram as potencialidades desta placa são brevemente discutidos.
Caderno Brasileiro de Ensino de Física, 2009
Most High School Physics programs begin with the study of motion. In order to understand the basi... more Most High School Physics programs begin with the study of motion. In order to understand the basic concepts it is necessary to quantify phenomena, which is not trivial, so, seldom used in the school classroom. Within the techniques that allow the necessary precise time measurements, the stroboscopic photography has been a good solution, in spite of the requirement of equipment such as a special lamp and the use of analogical photography or, alternatively, of a Polaroid camera that gives immediate results. A possible answer is to produce stroboscopic digital pictures of motions, using two accessories at the disposal of most teachers and at very low cost: a digital camera, to produce a video of the phenomenon in study and a PC Computer together with a free software, VirtualDub and ImageJ to produce the stroboscopic picture. The data for analysis may be obtained in analogical or digital format, show good quality, as seen in the examples presented.
Materials Science and Engineering: A, 2011
TIMETAL 54M (in the following Ti-54M) is a newly developed (α+β) titanium alloy with nominal comp... more TIMETAL 54M (in the following Ti-54M) is a newly developed (α+β) titanium alloy with nominal composition Ti-5Al-4V-0.6Mo-0.4Fe. The alloy can provide a cost benefit over Ti-6Al-4V due to improved machinability and formability. These attractive properties might be a driving force for replacing Ti-6Al-4V in many aircraft as well as biomedical applications. Since HCF performance is one of the most important requirements for these
Materials Research, 2007
The objective of this study was to investigate how mechanical surface treatments performed for re... more The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram ® Zirconia). Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing). Fracture toughness was accessed through indentation strength test (IS). X ray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1) introduced defects which decreased the fracture toughness and reliability, presenting the lowest K IC. On the other hand, grinding followed by sandblasting and annealing (group 3) presented the highest K IC. Sandblasting (group 2) presented the highest reliability but lower K IC compared to group 3.
Journal of the Brazilian Chemical Society, 2000
O sal pentacianonitrosilrutenato(II) de potássio, em forma amorfa, foi sintetizado e caracterizad... more O sal pentacianonitrosilrutenato(II) de potássio, em forma amorfa, foi sintetizado e caracterizado por espectroscopias UV, IR, difração de raios X e análise termogravimétrica. Amostras irradiadas por raios X revelam, por espectroscopia de Ressonância Paramagnética Eletrônica, a presença de complexos paramagnéticos de rutênio (I) e de radicais NO 2. Os parâmetros do hamiltoniano de spin medidos para o complexo [Ru(CN) 5 NO] 3-(g ⊥ = 2.0064, A ⊥ (14 N) = 60.7 MHz, g || = 1.999, A || (14 N) = 77.3 MHz) indicam uma captura eletrônica em um orbital molecular π* do grupo nitrosil com a participação de orbitais d xz and d yz do rutênio, como recentemente previsto por cálculos teóricos. Íons de prata, presentes como impurezas oriundas da rota sintética, são reduzidos a Ag(0) durante a irradiação e interagem com quatro nitrogênios equivalentes em um sítio distorcido, originando um espectro de RPE anisotrópico. Amorphous potassium pentacyanonitrosylruthenate (II) was synthesized and characterized by UV, IR, X-ray diffraction and thermogravimetric analysis. Electron Spin Resonance spectroscopy reveals the presence of paramagnetic ruthenate (I) complexes and NO 2 radicals in the X-irradiated diamagnetic salt. Spin-hamiltonian parameters of the [Ru(CN) 5 NO] 3complex (g ⊥ = 2.0064, A ⊥ (14 N) = 60.7 MHz, g || = 1.999, A || (14 N) = 77.3 MHz) support an electron capture in a π* molecular orbital of the nitrosyl group mixed with d xz and d yz ruthenium orbitals as recently predicted by theoretical calculations. Silver ions, present as impurities, are reduced to Ag(0) by X-irradiation and coordinate to four magnetically equivalent nitrogens in a distorted site, giving rise to a well resolved anisotropic ESR powder spectrum.
Journal of Materials Science Letters, 1996
Journal of Materials Science Letters, 1990
Hyperfine Interactions, 2006
The crystal structure of synthetic ferrous hureaulite, Fe 5 2+ (H 2 O) 4 (PO 4 H) 2 (PO 4) 2 , wa... more The crystal structure of synthetic ferrous hureaulite, Fe 5 2+ (H 2 O) 4 (PO 4 H) 2 (PO 4) 2 , was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å , b=96.27(3)-, V=1463.6(6) Å 3 , Z=4 and D calc =3.327 g/cm 3. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO 4) 3+ and acid (PO 4 H) 2+ tetradentate groups. These are centered on Fe 2+ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe 2+ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mö ssbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites.
Anais da Academia Brasileira de Ciências, 2009
This report describes the characterization of a sedimentary occurrence from the Parnaíba Basin, B... more This report describes the characterization of a sedimentary occurrence from the Parnaíba Basin, Brazil, containing the zeolite stilbite intertwined with smectitic clay mineral. The head samples from different sites present a wide content range of the zeolitic phase - 15% to 50%. The use of simple separation techniques - conventional gravitic treatments - yields concentrates containing about 67% of the zeolitic component. Assays with the amendments of these concentrates with plant nutrients yield release rates matching those reported for similar commercial products.
Origins of Life and Evolution of Biospheres, 1995
A non-enzymatic formation of 5′-ADP starting from phosphorylation of 5′-AMP in the presence of ei... more A non-enzymatic formation of 5′-ADP starting from phosphorylation of 5′-AMP in the presence of either calcium phosphate or calcium pyrophosphate precipitates is reported. This reaction is taken as a model for the study of heterogeneous catalysis of transphosphorylation in prebiotic conditions. Experiments were performed in completely aqueous media and in media containing dimethyl sulfoxide (Me2S0), to simulate periods of dehydration in primitive aquatic environments. It has been observed that the nucleotide is adsorbed onto both calcium phosphate and calcium pyrophosphate in accordance with Langmuir isotherms. Adsorptive capacity and affinity of the precipitates for nucleotide are changed by the presence of Me2SO, suggesting that the interaction between biomonomers and surfaces can be modulated by the degree of hydration of the anionic components of these compounds. In completely aqueous environments, formation of 5′-ADP from 5′-AMP adsorbed on precipitates of calcium phosphate and calcium pyrophosphate is very small. However, in the presence of 60% Me2SO this synthesis increases by factors of 3 and 6 for surfaces of calcium phosphate and calcium pyrophosphate, respectively, and follows first-order kinetics. Determinations of free energy changes show that phosphorylation of 5′-AMP adsorbed to these precipitates is thermodynamically favorable. Depending on the precipitation time of the samples and the composition of the medium, structural analysis of these precipitates by electron and X-ray diffraction shows changes in their cristallinity grade. It is proposed that these changes are responsible for the modulation of the quantity of adsorbed nucleotides to the surface of solid matrices as well as the catalytic activity of the precipitates.
Origins of Life and Evolution of Biospheres, 1999
Caderno Brasileiro de Ensino de Física
Neste trabalho apresentamos um projeto de construção de um marégrafo baseado num telêmetro ultras... more Neste trabalho apresentamos um projeto de construção de um marégrafo baseado num telêmetro ultrassônico controlado por uma placa Arduino Uno. O projeto é de fácil construção e de baixo custo e tem por objetivo viabilizar o estudo do fenômeno das marés oceânicas integrando atividades investigativas com a prática experimental. O fenômeno das marés se mostra uma excelente oportunidade para o estudo da gravitação universal de Isaac Newton e do estudo do movimento orbital do sistema Terra – Lua – Sol, dos quais é um resultado direto. Neste artigo, focalizamos basicamente a montagem experimental e apresentamos alguns resultados preliminares. Reservamos para um próximo artigo sugestões de aplicações em eventos investigativos bem definidos envolvendo o modelo newtoniano para o fenômeno das marés.
Origins Life Evol Biosphere, 1995
Revista Brasileira de Ensino de Física, 2015
Neste trabalho apresentamos uma experiência simples de condução térmica usando sensores de temper... more Neste trabalho apresentamos uma experiência simples de condução térmica usando sensores de temperatura digitais com tecnologia one-wire(um-fio) associados a uma placa Arduino para controle e aquisição de dados. Os sensores utilizados são acessóveis e podem ser facilmente encontrados no mercado nacional. O modelo experimental reproduz uma experiência clássica de condução térmica usada comumente em livros didáticos de física para apresentar e discutir a lei de Fourier da condução térmica. Os resultados se mostraram suficientemente sensíveis para revelar uma distribuição não linear de temperaturas numa situação em que condições de contorno pouco realistas, e comumente aplicadas à lei de Fourier nos livros didáticos, resulta num comportamento linear.
CrystEngComm, 2015
The structure of a magnetic two-dimensional CuII–MnII heterometallic coordination polymer was sol... more The structure of a magnetic two-dimensional CuII–MnII heterometallic coordination polymer was solved by using synchrotron X-ray powder diffraction.
Revista Brasileira de Ensino de Física, 2014
Apresentamos uma montagem experimental simples para o estudo da maré atmosférica, baseada no uso ... more Apresentamos uma montagem experimental simples para o estudo da maré atmosférica, baseada no uso da placa Arduino Uno. Com essa montagem, o professor de física no Ensino Médio poderá apresentar para seus alunos as oscilações barométricas, um efeito fundamentalmente de origem térmica devido ao aquecimento da atmosfera produzido pela radiação solar. Apresentamos também uma comparação entre a maré atmosférica e o efeito gravitacional da maré oceânica, destacando as diferenças entre os dois fenômenos.
The structure of ammonium azide (N H 4) N 3was (re-)dete r - minated ab initi ofrom x-ray powder ... more The structure of ammonium azide (N H 4) N 3was (re-)dete r - minated ab initi ofrom x-ray powder diffraction experiment usin g synchrotron radiation. We tried to detail and comment the differen t steps involved in the structure determination. The compound cryst a - llize in the orthorhombic Pmna space group (no.53) with a= 8.937(1 ) Å, b= 3.8070(5)
Cellular Origin and Life in Extreme Habitats and Astrobiology, 2004
ADSORPTION AND CATALYSIS OF NUCLEOTIDE HYDROLYSIS BY PYRITE IN MEDIA SIMULATING PRIMEVAL AQUEOUS ... more ADSORPTION AND CATALYSIS OF NUCLEOTIDE HYDROLYSIS BY PYRITE IN MEDIA SIMULATING PRIMEVAL AQUEOUS ENVIRONMENTS ADALBERTO VIEYRA1, ANA ... in artificial seawater promotes breakdown of the (3, 7-and the a,(}-phosphoanhydride bond of ATP ...
Revista Brasileira de Ensino de Física, 2011
Neste trabalho, apresentamos a placa Arduino como uma opção de muito baixo custo para a aquisição... more Neste trabalho, apresentamos a placa Arduino como uma opção de muito baixo custo para a aquisição de dados com um PC. Duas aplicações simples que mostram as potencialidades desta placa são brevemente discutidos.
Caderno Brasileiro de Ensino de Física, 2009
Most High School Physics programs begin with the study of motion. In order to understand the basi... more Most High School Physics programs begin with the study of motion. In order to understand the basic concepts it is necessary to quantify phenomena, which is not trivial, so, seldom used in the school classroom. Within the techniques that allow the necessary precise time measurements, the stroboscopic photography has been a good solution, in spite of the requirement of equipment such as a special lamp and the use of analogical photography or, alternatively, of a Polaroid camera that gives immediate results. A possible answer is to produce stroboscopic digital pictures of motions, using two accessories at the disposal of most teachers and at very low cost: a digital camera, to produce a video of the phenomenon in study and a PC Computer together with a free software, VirtualDub and ImageJ to produce the stroboscopic picture. The data for analysis may be obtained in analogical or digital format, show good quality, as seen in the examples presented.
Materials Science and Engineering: A, 2011
TIMETAL 54M (in the following Ti-54M) is a newly developed (α+β) titanium alloy with nominal comp... more TIMETAL 54M (in the following Ti-54M) is a newly developed (α+β) titanium alloy with nominal composition Ti-5Al-4V-0.6Mo-0.4Fe. The alloy can provide a cost benefit over Ti-6Al-4V due to improved machinability and formability. These attractive properties might be a driving force for replacing Ti-6Al-4V in many aircraft as well as biomedical applications. Since HCF performance is one of the most important requirements for these
Materials Research, 2007
The objective of this study was to investigate how mechanical surface treatments performed for re... more The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram ® Zirconia). Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing). Fracture toughness was accessed through indentation strength test (IS). X ray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1) introduced defects which decreased the fracture toughness and reliability, presenting the lowest K IC. On the other hand, grinding followed by sandblasting and annealing (group 3) presented the highest K IC. Sandblasting (group 2) presented the highest reliability but lower K IC compared to group 3.
Journal of the Brazilian Chemical Society, 2000
O sal pentacianonitrosilrutenato(II) de potássio, em forma amorfa, foi sintetizado e caracterizad... more O sal pentacianonitrosilrutenato(II) de potássio, em forma amorfa, foi sintetizado e caracterizado por espectroscopias UV, IR, difração de raios X e análise termogravimétrica. Amostras irradiadas por raios X revelam, por espectroscopia de Ressonância Paramagnética Eletrônica, a presença de complexos paramagnéticos de rutênio (I) e de radicais NO 2. Os parâmetros do hamiltoniano de spin medidos para o complexo [Ru(CN) 5 NO] 3-(g ⊥ = 2.0064, A ⊥ (14 N) = 60.7 MHz, g || = 1.999, A || (14 N) = 77.3 MHz) indicam uma captura eletrônica em um orbital molecular π* do grupo nitrosil com a participação de orbitais d xz and d yz do rutênio, como recentemente previsto por cálculos teóricos. Íons de prata, presentes como impurezas oriundas da rota sintética, são reduzidos a Ag(0) durante a irradiação e interagem com quatro nitrogênios equivalentes em um sítio distorcido, originando um espectro de RPE anisotrópico. Amorphous potassium pentacyanonitrosylruthenate (II) was synthesized and characterized by UV, IR, X-ray diffraction and thermogravimetric analysis. Electron Spin Resonance spectroscopy reveals the presence of paramagnetic ruthenate (I) complexes and NO 2 radicals in the X-irradiated diamagnetic salt. Spin-hamiltonian parameters of the [Ru(CN) 5 NO] 3complex (g ⊥ = 2.0064, A ⊥ (14 N) = 60.7 MHz, g || = 1.999, A || (14 N) = 77.3 MHz) support an electron capture in a π* molecular orbital of the nitrosyl group mixed with d xz and d yz ruthenium orbitals as recently predicted by theoretical calculations. Silver ions, present as impurities, are reduced to Ag(0) by X-irradiation and coordinate to four magnetically equivalent nitrogens in a distorted site, giving rise to a well resolved anisotropic ESR powder spectrum.
Journal of Materials Science Letters, 1996
Journal of Materials Science Letters, 1990
Hyperfine Interactions, 2006
The crystal structure of synthetic ferrous hureaulite, Fe 5 2+ (H 2 O) 4 (PO 4 H) 2 (PO 4) 2 , wa... more The crystal structure of synthetic ferrous hureaulite, Fe 5 2+ (H 2 O) 4 (PO 4 H) 2 (PO 4) 2 , was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å , b=96.27(3)-, V=1463.6(6) Å 3 , Z=4 and D calc =3.327 g/cm 3. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO 4) 3+ and acid (PO 4 H) 2+ tetradentate groups. These are centered on Fe 2+ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe 2+ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mö ssbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites.
Anais da Academia Brasileira de Ciências, 2009
This report describes the characterization of a sedimentary occurrence from the Parnaíba Basin, B... more This report describes the characterization of a sedimentary occurrence from the Parnaíba Basin, Brazil, containing the zeolite stilbite intertwined with smectitic clay mineral. The head samples from different sites present a wide content range of the zeolitic phase - 15% to 50%. The use of simple separation techniques - conventional gravitic treatments - yields concentrates containing about 67% of the zeolitic component. Assays with the amendments of these concentrates with plant nutrients yield release rates matching those reported for similar commercial products.
Origins of Life and Evolution of Biospheres, 1995
A non-enzymatic formation of 5′-ADP starting from phosphorylation of 5′-AMP in the presence of ei... more A non-enzymatic formation of 5′-ADP starting from phosphorylation of 5′-AMP in the presence of either calcium phosphate or calcium pyrophosphate precipitates is reported. This reaction is taken as a model for the study of heterogeneous catalysis of transphosphorylation in prebiotic conditions. Experiments were performed in completely aqueous media and in media containing dimethyl sulfoxide (Me2S0), to simulate periods of dehydration in primitive aquatic environments. It has been observed that the nucleotide is adsorbed onto both calcium phosphate and calcium pyrophosphate in accordance with Langmuir isotherms. Adsorptive capacity and affinity of the precipitates for nucleotide are changed by the presence of Me2SO, suggesting that the interaction between biomonomers and surfaces can be modulated by the degree of hydration of the anionic components of these compounds. In completely aqueous environments, formation of 5′-ADP from 5′-AMP adsorbed on precipitates of calcium phosphate and calcium pyrophosphate is very small. However, in the presence of 60% Me2SO this synthesis increases by factors of 3 and 6 for surfaces of calcium phosphate and calcium pyrophosphate, respectively, and follows first-order kinetics. Determinations of free energy changes show that phosphorylation of 5′-AMP adsorbed to these precipitates is thermodynamically favorable. Depending on the precipitation time of the samples and the composition of the medium, structural analysis of these precipitates by electron and X-ray diffraction shows changes in their cristallinity grade. It is proposed that these changes are responsible for the modulation of the quantity of adsorbed nucleotides to the surface of solid matrices as well as the catalytic activity of the precipitates.
Origins of Life and Evolution of Biospheres, 1999