Neste trabalho investiga-se o comportamento resistente de vigas de concreto com taxas reduzidas de armadura transversal, analisando-se as possibilidades de melhoria de desempenho pelo reforço do concreto com fibras curtas de aço e polipropileno e pela aplicação da protensão, através de ensaios em vigas de seção quadrada e vigas protendidas de seção duplo-T. Apresenta-se também uma revisão de conhecimentos sobre o comportamento estrutural de elementos de concreto armado ou protendido, com ênfase nas solicitações por força cortante e os principais conceitos sobre os compósitos constituídos de matriz de cimento reforçada com fibras. As principais alterações decorrentes da introdução das fibras foram o aumento da resistência ao cisalhamento, da rigidez após a fissuração e da dutilidade. A protensão aumenta a resistência ao cisalhamento, a resistência à fissuração e a extensão da zona não fissurada, e torna as bielas mais abatidas. Tanto as fibras quanto a protensão proporcionam alívio da tensão nos estribos. / This thesis presents an experimental analysis of the structural behavior of concrete beams with reduced shear reinforcement ratios. Improvements on performance due to prestressing and steel and polypropilene fibers are analized in rectangular and T beam models. A state-of-the-art is presented on shear strength of reinforced and prestressed concrete beams and on fiber reinforced cement-based composites. The main effects due to fiber addition are the increasing of the shear strength, post-cracking stiffiness and ductility. Prestressing helps to increase the shear strength, cracking strength and extension of the non-cracked zone and it turns the struts less inclined. Fibers as well prestressing reduce the stresses on stirrups.

The concept of stay-in-place (SIP) structural formwork has the potential to simplify and accelerate the construction process to a great extent. Fibre-reinforced polymer (FRP) SIP structural formwork offers further potential benefits over existing formwork systems in terms of ease and speed of construction, improved site safety and reduced long-term maintenance in corrosive environments. However, it is not without its limitations, including primarily the possibility of a lack of ductility, which is a key concern regarding the use of FRP structural formwork in practice. This thesis presents the findings of an experimental and analytical investigation into a novel FRP SIP structural formwork system for a concrete slab with a particular emphasis on its ability to achieve a ductile behaviour. The proposed composite system consists of a moulded glass fibre-reinforced polymer (GFRP) grating adhesively bonded to square pultruded GFRP box sections. The grating is subsequently filled with concrete to form a concrete-FRP composite floor slab. Holes cut into the top flange of the box sections allow concrete studs to form at the grating/box-section interface. During casting, GFRP dowels are inserted into the holes to further mechanically connect the grating and box sections. An initial experimental investigation into using GFRP grating as confinement for concrete showed that a significant increase in ultimate strength and strain capacity could be achieved compared to unconfined concrete. This enhanced strain capacity in compression allows greater use of the FRP capacity in tension when used in a floor slab system. Further experimental investigation into developing ductility at the grating/box-section interface showed that the proposed shear connection exhibited elastic-‘plastic’ behaviour. This indicated the feasibility of achieving ductility through progressive and controlled longitudinal shear failure. Following these component tests on the concrete-filled grating and the shear connectors, a total of six (300 x 150 x 3000) mm slab specimens were designed and tested under five-point bending. It was found that the behaviour of all specimens was ductile in nature, demonstrating that the proposed progressive longitudinal shear failure was effective. A three-stage analytical model was developed to predict the load at which the onset of longitudinal shear failure occurred, the stiffness achieved during the post elastic behaviour and, finally, the deflection at which ultimate failure occurred. Close agreement was found between experimental results and the theory.

This work aims to obtain the fusion excitation function for the 16O+16O system through gamma-spectroscopy measurements and gamma-charged particle coincidence, using the Saci-Perere system mounted at the end of the 30A beamline of the Open Laboratory of Nuclear Physics of the University of São Paulo (LAFN). Tests with the gamma-charged particle detection system indicated its unfeasibility due to the short measurement time and lose of the neutron channel. To overcome this problem, a new experimental setup was used. Two $\\gamma$-ray detectors were placed at 55º and 125º and a surface barrier detector was placed at 130º to monitor the 16O nuclei backscattered. The partial fusion cross sections related to the exit channels from the 16O+16O fusion reaction were measured by detecting their characteristic gamma rays at Ecm= 8.27, 9.27, 10.77 and 12.27 MeV. Three difficulties were faced during and after the experiment: carbon contamination of the target, natural background and low beam intensity. Efforts were made to successfully overcome these difficulties. The relative normalization was made by two ways, using the gamma-rays at 279 keV(197Au) and 536 keV(100Mo), and their results agree very well with each other. The total fusion cross section was obtained by summing the partial cross sections for each beam energy. Its absolute normalization was performed with the total theoretical fusion cross section obtained using coupled channel calculations, using the zero point motion model (ZPM), at Ecm= 12.27 MeV. With the total fusion cross section we calculated the astrophysical S-factor, and both results are in good agreement with the literature. / O objetivo deste trabalho é obter uma função de excitação para o sistema 16O+16O através de medidas de espectroscopia-gamma e coincidência gamma-partícula carregada, utilizando o sistema Saci-Perere montado no final da linha de feixe 30A do Laboratório Aberto de Física Nuclear da Universidade de São Paulo (LAFN). Testes com o sistema de detecção gamma-partícula carregada indicaram sua inviabilidade devido ao curto tempo de medida e a perda do canal de nêutrons. Para superarmos este problema, uma nova configuração experimental foi utilizada. Dois detectores de radiação gamma foram posicionados a 55º e 125º e um detector de barreira de superfície foi posicionado a 130º para monitorar os núcleos de 16O retroespalhados. As seções de choque parciais relativas aos canais de saída da reação de fusão 16O+16O foram medidas através da detecção de seus raios-gamma característicos para Ecm= 8.27, 9.27, 10.77 e 12.27 MeV. Três dificuldades foram encontradas ao longo e após o experimento: contaminação do alvo por carbono, radiação natural de fundo e baixa intensidade do feixe. Esforços foram direcionados com sucesso para superar estas dificuldades. A normalização relativa foi realizada por dois caminhos, utilizando os raios-gamma a 279 keV(197Au) e a 536 keV(100Mo), e seus resultados concordam muito bem. A seção de choque de fusão total foi obtida somando as seções de choque parciais para cada energia de feixe medida. Sua normalização absoluta foi feita usando a seção de choque de fusão teórica total obtida com cálculos de canais acoplados, utilizando o modelo (ZPM), para Ecm= 12.27 MeV. De posse da seção de choque de fusão total calculamos o fator S-astrofísico, e ambos os resultados concordam bem com a literatura.

[pt] No presente trabalho o método de Rayleigh-Ritz é utilizado na determinação dos campos modais e dos números de onda de corte em guias de onda de seção arbitrária. Inicialmente, o método é aplicado com funções de base polinomiais, sendo a seção transversal do guia aproximada por um polígono convexo. Este tipo de função limitou o número de modos que podem ser calculados, uma vez que polinômios de grau alto geram instabilidades computacionais e overflow. Utilizando a mesma metodologia, os campos modais em guias de onda superquadráticos são analisados. Entretanto, as funções de base polinomiais são substituídas por funções trigonométricas, produzindo um modelo numérico capaz de computar um grande número de modos em um tempo de execução razoável. Os guias superquadráticos constituem uma classe de guias uniformes, incluindo guias circulares, elípticos, quase retangulares e outros de seções intermediárias. Conseqüentemente, eles são úteis na construção de diversos dispositivos em guias de onda, incluindo transições de diferentes seções, tais como circular para elíptica e circular para retangular. O método do casamento de modos é aplicado na determinação da matriz de espalhamento de descontinuidades entre guias superquadráticos. Diversas aplicações numéricas são apresentadas e comparadas com resultados obtidos através de outras técnicas. / [en] In the present work, the modal fields and cutoff wavenumbers of arbitrary cross section waveguides are determined using the Rayleigh-Ritz method. Initially, the method is applied to waveguides with cross section approximated by a convex polygon. Polynomial basis functions are used. Such basis functions limit the number of modes that can be computed, since polynomials of high degree generate computer instabilities and overflow. Using the same methodology, the modal fields of superquadric waveguides are analyzed. Polynomial basis functions are replaced by trigonometric functions, however, producing an efficient numerical model capable of computing a large number of modes with a reasonable computer time. Superquadric waveguides constitute a class of uniform waveguides that include circular, elliptical, almost rectangular waveguides and a series of intermediate cross section waveguides. As a consequence they are quite useful in the construction of several devices, including transitions between waveguides of different cross sections, such as circular to elliptical and circular to rectangular. The mode matching technique is applied to the determination of the scattering matrix of discontinuities between superquadric waveguides. Several numerical applications are presented and compared to results obtained from other techniques.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-06-26T18:06:46Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Valeria Christino da Silva Amari.pdf: 1457650 bytes, checksum: 36d1c16d18bce8f0fe740dcc77307f0e (MD5) / Made available in DSpace on 2018-06-26T18:06:46Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Valeria Christino da Silva Amari.pdf: 1457650 bytes, checksum: 36d1c16d18bce8f0fe740dcc77307f0e (MD5) Previous issue date: 2018-05-18 / Devido ao aumento descontrolado da taxa de cesáreas no Brasil e no mundo, tem havido maior preocupação em relação às consequências para a saúde materno-infantil, tanto imediatas quanto a longo prazo, principalmente quando estas são realizadas de maneira cada vez mais frequente5 e sem indicação clínica. Diversos fatores podem influenciar a escolha do tipo de parto, estando os indicadores socioeconômicos entre os mais importantes. Este estudo objetivou avaliar as proporções e a tendência temporal das cesáreas nas Regionais de Saúde Estado do Paraná e correlacionar espacialmente com fatores socioeconômicos. Trata-se de um estudo ecológico com delineamento misto, descritivo de série temporal e transversal, com dados coletados do Sistema de Informações sobre Nascidos Vivos e do Instituto Brasileiro de Geografia e Estatística. As análises das proporções e da tendência temporal das cesáreas foram realizadas entre 2003 e 2014, por triênios. O mesmo foi feito para o Estado do Paraná e Brasil, para fins de comparação. Aplicou-se a estatística de Moran Global para detecção de agregados de eventos no espaço. Utilizou-se o Coeficiente de Correlação de Pearson para avaliar a correlação das proporções de cesáreas no triênio de 2009 a 2011 com a média dos indicadores socioeconômicos de cada Regional de Saúde do Estado do Paraná, de acordo com os dados do Censo Demográfico de 2010, sendo construídos mapas espaciais com as variáveis significativas. As maiores proporções de cesáreas ocorreram no triênio entre 2012 e 2014, exceto para a 1a Regional de Saúde (Paranaguá), com maiores proporções entre 2009 e 2011. Todas as regionais apresentaram tendência crescente na proporção de cesáreas, exceto a 1a regional que permaneceu com tendência estacionária. Na análise estatística espacial (Teste de Moran Global) para o triênio 2009 a 2011 as seguintes variáveis apresentaram-se significativas na análise univariada: proporções de cesáreas (p=0,01), percentual de domicílios com água encanada (p<0,01), coeficiente de Gini (p<0,001), razão de renda (p<0,001), percentual da população com renda menor que meio salário mínimo (p<0,001) e Índice de Desenvolvimento Humano (p=0,01). Houve correlação positiva entre a proporção de cesáreas e percentual de domicílios com água encanada (r=0,47; p=0,03) e Índice de Desenvolvimento Humano (r=0,60; p<0,001) e correlação negativa com coeficiente de Gini (r=-0,75; p<0,001), razão de renda (r=-0,72; p<0,001) e percentual da população com renda menor que meio salário mínimo (r=- 0,61; p<0,01). As proporções de cesáreas e os cinco indicadores socioeconômicos que apresentaram significância estatística foram representados espacialmente. A grande maioria das Regionais de Saúde do Paraná apresentou proporção de cesáreas superior à média do país e tendência crescente. Melhores indicadores socieconômicos foram correlacionados à maiores proporções de cesáreas. Enfatiza-se a necessidade de medidas interdisciplinares para redução nas proporções de cesáreas. / Due to the uncontrolled increase in cesarean rates in Brazil and in the world, there has been greater concern regarding the consequences for maternal and child health, both immediate and long term, especially when these are performed increasingly and without clinical indication. Several factors may influence the choice of delivery type, with socioeconomic indicators being the most important. This study aimed to evaluate the proportions and temporal trend of cesarean sections in the State of Paraná Health Region and correlate spatially with socioeconomic factors. An ecological study with a mixed and descriptive design of a temporal and transverse series, with data collected from the Information System on Live Births and the Brazilian Institute of Geography and Statistics. The analyzes of the proportions and the temporal trend of cesareans were performed between 2003 and 2014, for three years. The same was done for the State of Paraná and Brazil, for comparison purposes. The Moran Global statistic was applied to detect aggregates of events in space. The Pearson Correlation Coefficient was used to evaluate the correlation of the cesarean proportions in the triennium from 2009 to 2011 with the average of the socioeconomic indicators of each Health Region of the State of Paraná, according to data from the Demographic Census of 2010, spatial maps were constructed with the significant variables. The largest proportions of cesareans occurred in the triennium between 2012 and 2014, except for the 1st Regional Health (Paranaguá), with larger proportions between 2009 and 2011. All the regional ones showed an increasing tendency in the proportion of cesarean sections, except the regional one that remained with steady trend. In the spatial statistical analysis (Global Moran's Test) for the triennium 2009-2011, the following variables were significant in the univariate analysis: cesarean proportions (p = 0.01), percentage of households with running water (p <0.01) ), Gini coefficient (p <0.001), income ratio (p <0.001), percentage of the population with income less than half a minimum wage (p <0.001) and Human Development Index (p = 0.01). There was a positive correlation between the proportion of cesareans and percentage of households with running water (r = 0.47, p = 0.03) and Human Development Index (r = 0.60, p <0.001) and negative correlation with coefficient of (R = -0.72, p <0.001), and percentage of the population with income less than half a minimum wage (r = -0.61, p < 0.01). The proportions of cesareans and the five socioeconomic indicators that presented statistical significance were represented spatially. The vast majority of the Health Region of Paraná presented a higher proportion of caesarean sections than the country average and a growing trend. Better socioeconomic indicators were correlated with the higher proportions of cesarean sections. It is emphasized the need for interdisciplinary measures to reduce the proportion of cesarean sections.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-09-28T17:30:19Z No. of bitstreams: 1 Míriam Kênia.pdf: 3137468 bytes, checksum: 2a6d6c6a5a7a6f20c2a7cd6bf12cdaf3 (MD5) / Made available in DSpace on 2016-09-28T17:30:19Z (GMT). No. of bitstreams: 1 Míriam Kênia.pdf: 3137468 bytes, checksum: 2a6d6c6a5a7a6f20c2a7cd6bf12cdaf3 (MD5) Previous issue date: 2016-06-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The Research investigates the biopolitic convocations around child birth methods, C-section and normal birth, in the media, in relationship websites, social media and in the communication within the maternity centers. The speeches and narratives are built around fear and support the paradox: normal and safe to do is a C-section; strange and risky is the normal birth. This media strategy, considered a device in the Focault and Agamben concept, more than fulfill the position of spreading the word and legitimating the biopolitic speech, but is also responsible for building this model. The bio politic guidelines around childbirth are anchored in the control of the body and in bio economics, according to Nikolas Rose. By taking the woman from the scene and outsourcing the protagonist of child birth to the doctor, this assistance model makes the female body more controllable and productive. After all, the current biopolitic is focused in the increasing capacities to control, manage, plan, and remodeled the vital capacities. And how to do that? The media, with its convocations, teaches. It is also attempted to investigate, by means of Bodymedia theory, the changes in the body immersed in the C-section environment, that passes through cognitive changes and causes several other modifications in the environment / A pesquisa investiga as convocações biopolíticas em torno da via de nascimento, parto e cesariana, na imprensa, nos sites de relacionamento, nas redes sociais e na comunicação das maternidades. Os discursos e narrativas são construídos em torno do medo e sustentam o paradoxo: Normal e seguro é fazer cesariana. Estranho e arriscado é o parto. Essas mídias, consideradas dispositivos, no conceito de Foucault e Agamben, mais do que assumirem o papel de propagarem e legitimarem o discurso biopolítico em prol da cesariana, fazem parte da construção desse modelo. As diretrizes biopolíticas em torno do nascimento são ancoradas no controle do corpo e na bioeconomia, de acordo com Nikolas Rose. Ao tirar a mulher de cena e terceirizar o protagonismo do nascimento para o médico, esse modelo de assistência tonar o corpo feminino mais controlado e produtivo. Afinal, a biopolítica atual está focada nas crescentes capacidades de controlar, administrar, projetar e remodelar as próprias capacidades vitais. E como fazer isso? A mídia, com as suas convocações, ensina. Busca-se também investigar, por meio da teoria corpomídia, as mudanças no corpo imerso nesse ambiente cesarista, que passar por mudanças cognitivas e provoca outras tantas nesse ambiente

Medidas das secções de choque de fotonêutrons do 9Be, 13C e 17O foram obtidas no intervalo de energia entre 1,6 e 10,8 MeV, utilizando radiação gama de alta resolução em energia (3 a 21 eV) produzida na captura de nêutrons térmicos por 21 materiais alvo, quando posicionados no interior de um canal tangencial, junto ao núcleo do reator de pesquisa IEAR1 (5 MW) do IPEN/CNEN-SP. As amostras foram irradiadas no interior de um sistema detector de nêutrons “Long Counter", de geometria 4&#960;, a 520,5 cm de distância do alvo de captura. O fluxo de raios gama foi determinado por meio da análise do espectro gama obtido fazendo uso de um detector de estado sólido do tipo Ge(Li) (EG&G ORTEC, 25 cm3, 5%), previamente calibrado com raios gama de captura produzidos por uma amostra padrão de nitrogênio (Melamina). A secção de choque de fotonêutron foi medida para o espectro de raios gama de captura de cada alvo (secção de choque composta). Uma metodologia de inversão de matrizes para a resolução de problemas inverso discretos foi utilizada para a deconvolução do conjunto de valores experimentais da secção de choque composta, com a finalidade de obter a secção de choque em valores específicos de energia de excitação (energia das linhas gama principais dos alvos de captura). As secções de choque obtidas, nas energias das linhas gama principais de todos os alvos, foram comparadas com as medidas realizadas por outros autores utilizando diferentes fontes de radiação gama. Uma boa concordância foi observada entre os resultados experimentais deste trabalho com as relatados na literatura. / Photoneutron cross sections measurements of 9Be, 13C e 17O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4&#960; geometry neutron detector system “Long Counter", 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector(EG&G ORTEC, 25 cm3, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature.

Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.

The Higgs boson and the top quark have been a focus in modern elementary particle physics research because of their special roles in the Standard Model (SM) of particle physics. The studies of both particles are crucial for revealing the unsolved puzzles of modern particle physics. The coupling between the Higgs boson and the top quark, the top-Yukawa coupling, is one of the fundamental parameters in the SM that can potentially direct the future development of the theory of elementary particle physics. This thesis presents two analyses on the Higgs boson and the top quark, using proton-proton (pp) collision data collected by the ATLAS detector during 2012 and 2015. A search for the SM Higgs boson produced in association with a top quark pair (tt̄H) was performed using 20.3 fb⁻¹ of pp collision data at a centre-of-mass energy of √s = 8 TeV. The search is designed to be primarily sensitive to the H → bb decay mode. Events with one of two electrons or muons are used in the search. No significant excess of events is observed above the background predicted by the SM. An observed (expected) upper limit on the signal strength of 3.4 (2.2) times the SM prediction is obtained at 95% confidence level. The tt̄H signal strength, represented by the ratio of the measured tt̄H cross-section to the SM prediction, is found to be μ = 1.5 ± 1.1 for a Higgs boson mass of m_H = 125 GeV. A measurement of the top quark pair (tt̄) production cross-section was performed using 3.2 fb⁻¹ of pp collision data at √s = 13 TeV. The measurement uses events with an opposite-charge-sign electron-muon pair and exactly one and two jets originating from b quarks. The inclusive tt̄ production cross-section is measured to be σ_tt̄ = 818 ± 8(stat) ± 27(syst) ± 19(lumi) ± 12(beam) pb, where the uncertainties arise from data statistics, analysis systematic effects, the integrated luminosity and the LHC beam energy. The total relative uncertainty is 4.4%. The result is consistent with the theoretical prediction at the next-to-next-to-leading order accuracy in the strong coupling constant αs of QCD, with the resummation of next-to-next-to-leading logarithmic (NNLL) soft gluon terms. A fiducial cross-section corresponding to the experimental acceptance of leptons is also measured.

The amino acid sequence of a protein determines its 3D fold, the ease with which its native structure is formed, its function, the conformational preferences sampled and the tendency to interact with itself (aggregation) and binding partners. In addition, certain conformational preferences can lead to dysfunction resulting in different diseased states in organisms. All of these conformations can be described by a protein's energy landscape; a native (functional) state being localised at the energy minimum. As protein dynamics is crucial to function it is important to monitor the sampling of different conformations. Thus the work in this thesis reports on two methods for monitoring protein conformation and conformational change in the gas phase using ion mobility mass spectrometry (IM-MS). The measurement from IM-MS methods allow the determination of a collision cross section (CCS) which is an indicator of a molecule's 3D shape. First, the effect of charge on protein structure is investigated by manipulation of protein charge, post electrospray ionisation (ESI), by exposure to radical anions of the electron transfer reagent, 1,3-dicyanaobenzene; the charge reduced products formed are the result of electron transfer to the charged protein without any dissociation (ETnoD). IM-MS is used to monitor the conformational preferences of the altered and unaltered precursor and its products. Secondly, intermediate (transient) conformers are formed by activating the charged protein in the source region of an instrument post ESI. Activation of the protein precursor allows the sampling of different conformational preferences after energetic barriers have been overcome; IM-MS following activation allows for the monitoring of protein conformational change before and after. Further, variable temperature (VT) IM-MS allows for the deduction of intermediate structures with a focus on measurements at cryogenic temperatures whereby intermediate structures can be 'frozen out' post activation; intermediate structures which would otherwise anneal out at room temperature. With both methods a range of conformer populations are mapped for different protein molecules sampled upon different energetic inputs (via activation) and the disruption of intramolecular neutralising contacts/salt bridges (via charge reduction) one of the main interactions responsible for maintaining the structural integrity (3D fold) of proteins.