668 resultados para Modifier
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Background: Type 2 diabetes is linked to several complications which add to both physical and mental distress. Depression is a common co-morbidity of diabetes which can occur both as a cause and a consequence of type 2 diabetes. Depression has been shown to correlate with glucose regulation and treating depression might prove beneficial for glucose regulation as well as for mental well being. Another complication which might affect diabetes management is cognitive decline. Several risk factors and complications of diabetes might modify the risk for developing cognitive impairment, which is increased 1.5 times among subjects with type 2 diabetes. Type 2 diabetes, depression and impaired cognitive performance have all been linked to low birth weight. This thesis aimed to explore the effects and interactions of birth weight, depression and cognitive ability in relation to type 2 diabetes from a life course perspective. Subjects and methods: Studies I, II and V were part of the Helsinki Birth Cohort Study. 2003 subjects participated in an extensive clinical examination at an average age of 61 years. A standard glucose tolerance test (OGTT) was performed and depressive symptoms were assessed using the Beck Depression Inventory (BDI). In addition data was obtained from child welfare clinics and national registers. A subset of the cohort (n=1247) also performed a test on cognitive performance (CogState ®) at the average age of 64. Studies III and IV were randomised clinical trials where mildly depressed diabetic subjects were treated with paroxetine or placebo and the effect on metabolic parameters and quality of life was assessed. The first trial included 14 women and lasted 10 weeks, while the second trial included 43 subjects, both men and women, and lasted 6 months. Results: Type 2 diabetes was positively associated with the occurrence of depressive symptoms. Among diabetic subjects 23.6% had depressive symptoms, compared to 16.7% of subjects with normal glucose tolerance (OR = 1.77, p<0.001). Formal mediation analysis revealed that cardiovascular disease (CVD) is likely to act as a mediator in the association. Furthermore, low birth weight was found to modify the association between type 2 diabetes, CVD and depression. The association between BDI score and having type 2 diabetes or CVD was twice as strong in the subgroup with low birth weight (≤ 2500g) compared with the group with birth weight > 2500g (p for interaction 0.058). In the six months long randomised clinical trial (study IV) paroxetine had a transient beneficial effect on glycosylated haemoglobin A1c (GHbA1c) and quality of life when compared to placebo after three months of treatment. In study V we found that subjects with known diabetes had a consistently poorer level of cognitive performance than subjects with normal glucose tolerance in most of the tested cognitive domains. This effect was further amplified among those born with a small birth weight (p for interaction 0.002). Conclusions: Type 2 diabetes is associated with a higher occurrence of depressive symptoms compared to subjects with normal glucose tolerance. This association is especially strong among subjects with CVD and those born with a low birth weight. Treating depressed diabetic subjects with paroxetine has no long term effect on glucose regulation. Physicians should be aware of depression as an important co-morbidity of type 2 diabetes. Both depression and the cognitive decline often seen among diabetic subjects are increased if the subject is born with a low birth weight. Physicians should recognise low birth weight as an additional risk factor and modifier of diabetic complications.
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Elastic properties of potassium and lead phosphotungstate glasses have been investigated using ultrasonic velocity measurements. The composition dependence of elastic moduli in WO3-K2O-P2O5 glasses suggests that at low alkali oxide concentrations the atomic ring size increases by network modification, which results in the decrease of elastic moduli. In the highly modified regime, due to the presence of coulombic interaction, the rate of decrease of elastic moduli is reduced. In the WO3-PbO-P2O5 glasses the behaviour of elastic moduli suggests that PbO behaves both as a network former and network modifier. The incorporation of PbO into the network is quantitatively determined by the concentration of P2O5 in the system. The results are consistent with the structural model proposed earlier, based on characterization studies.
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29Si chemical shifts in a wide variety of silicates in crystalline, glassy and gel states have been related to a parameter, P, which takes into account the electronegativity and the structural description of the silicate units as well as the ionic potential of the modifier cation. The relation, δ(ppm)=28.4 [1−exp(−P)]−110.5, besides having predictive value, satisfactorily accounts for all the available chemical-shifts data on silicates and shows the right kind of limiting behaviour, with δ approaching the Q0 value at large P.
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Photocatalytic degradation of municipal wastewater was investigated using reagent grade TiO2 and modified neodymium doped TiO2 hybrid nanoparticles. For the first time, surface modification of Nd3+ doped TiO2 hybrid nanoparticles were carried out with n-butylamine as surface modifier under mild hydrothermal conditions. The modified nanoparticles obtained were characterized by Powder XRD, FTIR, DLS, TEM, BET surface area, zeta potential and UV-Vis Spectroscopy. The characterization results indicated better morphology, particle size distribution and low agglomeration of the nanoparticles synthesized. It was found that photodegradation of wastewater using surface modified neodymium doped TiO2 nanoparticles was more compared to pure TiO2, which can be attributed to the doping and modification with n-butylamine.
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The radial distribution functions (RDFs) of five xLi2S.(1 - x)B2S3 glasses (x = 0.55, 0.60, 0.67, 0.71 and 0.75) have been determined from neutron diffraction experiments performed at the Institut Laue-Langevin, Grenoble. These glasses are prepared by casting a molten mixture of boron, sulphur and Li2S inside a controlled atmosphere glovebox. Addition of the Li2S Modifier is found gradually to suppress all peaks corresponding to interatomic distances > 3.5 angstrom, which implies that the structural entities present in these glasses become segmented, and therefore more ionic, as x increases. The assumption of the existence of four main structural entities based on four- and three-coordinated borons (the latter carrying bridging and/or non-bridging sulphurs) accounts for all the peaks present in the RDFs as a function of composition. Furthermore, in the most modified glass (x = 0.75), that which contains only 'isolated' BS33- triangles, there seems to be evidence for either octahedral or tetrahedral coordination of Li+ by S- ions
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Likely spatial distributions of network-modifying (and mobile) cations in (oxide) glasses are discussed here. At very low modifier concentrations, the ions form dipoles with non-bridging oxygen centres while, at higher levels of modification, the cations tend to order as a result of Coulombic interactions. Activation energies for cation migration are calculated, assuming that the ions occupy (face-sharing) octahedral sites. It is found that conductivity activation energy decreases markedly with increasing modifier content, in agreement with experiment.
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The ac conductivity and dielectric behaviors of sodium borovanadate glasses have been studied over wide ranges of composition and frequency. The de activation energies calculated from the complex impedance plots decrease linearly with the Na2O concentration, indicating that ionic conductivity dominates in these glasses. The possible origin of low-temperature departures of conductivity curves (from linearity) of vanadium-rich glasses in log sigma versus 1/T plots is discussed. The ac conductivities have been fitted to the Almond-West type power law expression with use of a single value of s. It is found that in most of the glasses s exhibits a temperature-dependent minimum. The dielectric data are converted into moduli (M*) and are analyzed using the Kohlrausch-William-Watts stretched exponential function, The activation barriers, W, calculated from the temperature-dependent dielectric loss peaks compare well with the activation barriers calculated from the de conductivity plots. The stretching exponent beta is found to be temperature independent and is not likely to be related as in the equation beta = 1 - s, An attempt is made to elucidate the origin of the stretching phenomena. It appears that either a model of the increased contribution of polarization energy (caused by the increased modifier concentration) and hence the increased monopole-induced dipole interactions or a model based on increased intercationic interactions can explain the slowing down of the primitive relaxation in ionically conducting glasses.
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Mesoporous beta-MnO2 has been prepared, characterized and demonstrated to possess excellent catalytic activity in the thermal decomposition of ammonium perchlorate. The observed unprecedentedly low decomposition temperatures, fast reaction rates and enhanced heat releases in the catalysed formulations make mesoporous beta-MnO2 promising as a high-performing ballistic modifier in AP-based composite solid rocket propellants.
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A new type of covalent bulk modified glassy carbon composite electrode has been fabricated and utilized in the simultaneous determination of lead and cadmium ions in aqueous medium. The covalent bulk modification was achieved by the chemical reduction of 2-hydroxybenzoic acid diazonium tetrafluroborate in the presence of hypophosphorous acid as a chemical reducing agent. The covalent attachment of the modifier molecule was examined by studying Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and the surface morphology was examined by scanning electron microscopy images. The electrochemistry of modified glassy carbon spheres was studied by its cyclic voltammetry to decipher the complexing ability of the modifier molecules towards Pb2+ and Cd2+ ions. The developed sensor showed a linear response in the concentration range 1-10 mu M with a detection limit of 0.18 and 0.20 mu M for lead and cadmium, respectively. The applicability of the proposed sensor has been checked by measuring the lead and cadmium levels quantitatively from sewage water and battery effluent samples.
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Rrp1B (ribosomal RNA processing1 homolog B) is a novel candidate metastasis modifier gene in breast cancer. Functional gene assays demonstrated that a physical and functional interaction existing between Rrp1b and metastasis modifier gene SIPA1 causes reduction in the tumor growth and metastatic potential. Ectopic expression of Rrp1B modulates various metastasis predictive extra cellular matrix (ECM) genes associated with tumor suppression. The aim of this study is to determine the functional significance of single nucleotide polymorphism (SNP) in human Rrp1B gene (1307 T > C; rs9306160) with breast cancer development and progression. The study consists of 493 breast cancer cases recruited from Nizam's Institute of Medical Sciences, Hyderabad, and 558 age-matched healthy female controls from rural and urban areas. Genomic DNA was isolated by non-enzymatic method. Genotyping was done by amplification refractory mutation system (ARMS-PCR) method. Genotypes were reconfirmed by sequencing and results were analyzed statistically. We have performed Insilco analysis to know the RNA secondary structure by using online tool m fold. The TT genotype and T allele frequencies of Rrp1B1307 T > C polymorphism were significantly elevated in breast cancer (chi (2); p = < 0.008) cases compared to controls under different genetic models. The presence of T allele had conferred 1.75-fold risk for breast cancer development (OR = 1.75; 95 % CI = 1.15-2.67). The frequency of TT genotype of Rrp1b 1307T > C polymorphism was significantly elevated in obese patients (chi (2); p = 0.008) and patients with advanced disease (chi (2); p = 0.01) and with increased tumor size (chi (2); p = 0.01). Moreover, elevated frequency of T allele was also associated with positive lymph node status (chi (2); p = 0.04) and Her2 negative receptor status (chi (2); p = 0.006). Presence of Rrp1b1307TT genotype and T allele confer strong risk for breast cancer development and progression.
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Engineering blend structure with tailor-made distribution of nanoparticles is the prime requisite to obtain materials with extraordinary properties. Herein, a unique strategy of distributing nanoparticles in different phases of a blend structure has resulted in >99% blocking of incoming electromagnetic (EM) radiation. This is accomplished by designing a ternary polymer blend structure using polycarbonate (PC), poly(vinylidene fluoride) (PVDF), and poly(methyl methacrylate) (PMMA) to simultaneously improve the structural, electrical, and electromagnetic interference shielding (EMI). The blend structure was made conducting by preferentially localizing the multi-wall nanotubes (MWNTs) in the PVDF phase. By taking advantage of pp stacking MWNTs was noncovalently modified with an imidazolium based ionic liquid (IL). Interestingly, the enhanced dispersion of IL-MWNTs in PVDF improved the electrical conductivity of the blends significantly. While one key requisite to attenuate EM radiation (i.e., electrical conductivity) was achieved using MWNTs, the magnetic properties of the blend structure was tuned by introducing barium ferrite (BaFe) nanoparticles, which can interact with the incoming EM radiation. By suitably modifying the surface of BaFe nanoparticles, we can tailor their localization under the macroscopic processing condition. The precise localization of BaFe nanoparticles in the PC phase, due to nucleophilic substitution reaction, and the MWNTs in the PVDF phase not only improved the conductivity but also facilitated in absorption of the incoming microwave radiation due to synergetic effect from MWNT and BaFe. The shielding effectiveness (SE) was measured in X and K-u band, and an enhanced SE of -37 dB was noted at 18 GHz frequency. PMMA, which acted as an interfacial modifier in PC/PVDF blends further, resulting in a significant enhancement in the mechanical properties besides retaining high SE. This study opens a new avenue in designing mechanically strong microwave absorbers with a suitable combination of materials.
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Questão de grande relevância, nos dias atuais, no âmbito da Ciência Política, diz respeito às decisões políticas tomadas pelo Supremo Tribunal Federal, o que se denomina ativismo judicial. O termo ativismo judicial indica que a Corte está deixando de se restringir à atividade interpretativa, para estabelecer novas condutas, criando direito novo. A tendência tem sido a de levar as questões políticas para serem debatidas no âmbito judicial, de forma que assuntos políticos passam a ser exteriorizados como jurídicos. Em todos esses temas, devemos ter em conta que o balizamento tanto da atividade política como da atuação jurídica é a Constituição. Todavia, o que se tem observado é que Supremo passou a adotar uma nova postura interpretativa, de modo a permitir que, por via hermenêutica, torne-se possível corrigir a lei, modificá-la ou mesmo criar direito novo onde a lei nada especifica, além de permitir a criação de normas de caráter constitucional por decisão judicial. Três casos importantes ilustram bem esse cenário: a verticalização das coligações, a instalação obrigatória de comissões parlamentares de inquérito e a perda de mandato decorrente da troca de partido. Por serem temas de cunho eminentemente político, as decisões judiciais proferidas nessas matérias enquadram-se bem no campo do ativismo judicial, daí por que foram escolhidos como estudos de caso. O objetivo da tese é identificar as causas dessa nova postura do Supremo Tribunal Federal, tendo em vista que ela rompe com o entendimento adotado na jurisprudência anterior, em que essas mesmas matérias eram consideradas estritamente políticas e, portanto, fora da competência decisória da Corte.
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[EN]Trans fatty acids are found naturally in foods, particularly in those derived from ruminant animals, such as beef and dairy cattle. Over the past few decades, human consumption of trans fatty acids has increased, but this has been mainly from products containing partially hydrogenated vegetable oils. The correlation of trans fatty acid consumption with diseases such as coronary heart disease has been cause for concern, and led to recommendations to reduce their consumption. Trans fatty acids, however, have differing effects on human health. Therefore, in foods produced from ruminant animals, it is important to know their trans fatty acid composition, and how to enrich or deplete fatty acids that have positive or negative health effects. This review will cover the analysis of trans fatty acids in beef, their origin, how to manipulate their concentrations, and give a brief overview of their health effects.
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Alguns autores entendem o declínio cognitivo como fator de risco para fragilidade. No entanto, outros estudos apresentam a fragilidade como fator de risco para declínio cognitivo. O presente estudo também entende a relação entre fragilidade e desempenho cognitivo neste sentido. Ainda são poucos os estudos que avaliaram esta associação na literatura internacional e não identificamos nenhum estudo conduzido no Brasil, ou mesmo na América Latina, que a tenha investigado. Este estudo tem como objetivo, investigar a associação entre a síndrome da fragilidade e desempenho cognitivo em idosos, e o efeito da escolaridade e da idade nesta associação. Para isto, analisaram-se dados seccionais da Fase 1 do Estudo da fragilidade em Idosos Brasileiros (Rede FIBRA - Fragilidade em Idosos Brasileiros), relativos à clientes de uma operadora particular de saúde, com 65 anos ou mais, residentes na zona norte da cidade do Rio de Janeiro. A população final de estudo foi de 737 idosos. O desempenho cognitivo foi avaliado através do Mini Exame do Estado Mental (MEEM). Foram considerados frágeis os indivíduos que apresentaram três ou mais das seguintes características: perda de peso não intencional (mais de 4,5Kg no último ano); sensação de exaustão auto-relatada; baixo nível de força de preensão palmar (sujeitos no primeiro quintil); baixo nível de atividade física (sujeitos no primeiro quintil do Minnesota) e lentificação da marcha (sujeitos no primeiro quintil). Também foram coletadas informações sobre características socioeconômicas e demográficas, apoio social, condições médicas e capacidade funcional. O desempenho cognitivo (MEEM) e a fragilidade foram analisados como variáveis dicotômicas. Avaliou-se o papel da idade e escolaridade como possíveis modificadoras de efeito na associação entre fragilidade e baixo desempenho cognitivo. A avaliação da associação entre fragilidade e desempenho cognitivo foi feita através de regressão logística multivariada. A variável idade se comportou como modificadora de efeito na associação entre fragilidade e desempenho cognitivo, x(5) = 806,97, p<0,0001. O mesmo não ocorreu com a variável escolaridade. Os idosos frágeis apresentaram uma maior prevalência de baixo desempenho cognitivo, quando comparados aos idosos não-frágeis ou pré-frágeis, nos três estratos estudados (65 a 74 anos;75 a 84 anos; >_85 anos), p<0,001. A associação entre fragilidade e baixo desempenho cognitivo foi encontrada somente em idosos com 75 anos ou mais, sendo OR bruto=2,68 (IC 95% 1,29 5,53) para idosos de 75 a 84 anos e OR bruto= 6,39 (IC 95% 1,82 - 22,42) para idosos de 85 anos ou mais. Após ajuste pelas condições de saúde, capacidade funcional e pelas variáveis socioeconômicas e demográficas, a associação entre fragilidade e baixo desempenho cognitivo se manteve nesses estratos, OR aj=2,78 (IC 95% 1,23 - 6,27) para 75 a 84 anos e OR aj=15,62 (IC 95% 2,20 110,99) para 85 anos ou mais. A síndrome da fragilidade está, portanto, associada ao baixo desempenho cognitivo em idosos. A idade revelou-se como modificadora de efeito nesta associação. Os idosos com idade mais avançada revelaram uma associação mais expressiva entre os dois fenômenos.
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FSodium phosphate tellurite glasses in the system (NaPO3)(x)(TeO2)(1-x) were prepared and structurally characterized by thermal analysis, vibrational spectroscopy, X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses, the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units, and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismotic units. The combined interpretation of the O 1s XPS data and the P-31 solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather the formation of homootomic P-O-P and Te-O-Te linkages is favored over mixed P-O-Te connectivities. As a consequence of this chemical segregation effect, the spatial sodium distribution is not random, as also indicated by a detailed analysis of P-31/No-23 rotational echo double-resonance (REDOR) experiments. ACHTUNGTRENUNG(TeO2)1 x were prepared and structurally characterized by thermal analysis,vibrat ional spectroscopy,X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses,the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units,and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismatic units. The combined interpretation of the O 1s XPS data and the 31P solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather,the formation of homoatomic P O P and Te O Te linkages is favored over mixed P O Te connectivities. As a consequence of this chemical segregation effect,the spatial sodium distribution is not random,as also indicated by a detailed analysis of 31P/23Na rotational echo double-resonance (REDOR) experiments.