Estudo das propriedades ópticas de pós cerâmicos à base de Zn3Ga2Ge2O10: X% Cr3+ (X = 0 ; 0,5 ; 0,75 ; 1,0)

Ceramic powders based on Zn3Ga2Ge2O10: Cr3+ X% (X = 0.0; 0.5; 0.75; 1.0) were synthesized by solid-state reaction method. The gallium-zinc germanate doped with chromium presents an interesting property of phosphorescence, that means, it is capable of emitting light when excited by a source of radiation, and such emission remains for some time after stopping the source. For this reason, these materials can be widely applied in night-vision surveillance, (through the use of solar energy, for example), electronic devices screen, emergency routes signals, control panels indicators in dark environments, etc. In this job were considered different amounts of dopant in order to perform a comparison of structural and photoluminescent properties. For that, some analyses were performed on samples, such as XRD, FT-Raman, SEM, UV-vis and photoluminescence measurements (PL). Such analysis allowed to infer that the presence of chromium results in no phase transformation, so that the four compositions have the same set of phases: cubic, rhombohedral and hexagonal. Although the structure was not changed, chromium influences other properties / characteristics of these materials. Examples are: increase of band-gap, decrease of average particle size, small changes in binding energy checked by Raman and especially the increase of photoluminescent property. The chromium ions have great ease in replacing gallium ions in octahedral sites, resulting in emission of light with a wavelength of about 700 nm (infrared region), which is justified by the spin-forbidden 2E 4A2 transition. In other words, chromium is a favorable luminescent center, acting as a trap in the crystal structure, since it imprisons the excitation energy easily and releases it gradually, allowing the phosphorescence. It was observed that the composition ... (Complete abastract click electronic access below)

Síntese, caracterização e avaliação biológica de quelatos metálicos contendo ligantes de origem natural

O trabalho que será aqui apresentado teve como finalidade reunir os resultados obtidos dentro do Laboratório de Organometálicos II em relação aos estudos realizados acerca da interação de íons metálicos com ligantes orgânicos naturais. Os dados apresentados foram obtidos pela autora deste trabalho, e também pelos professores Francisco Otávio Cintra Ferrarini, José Roberto Stefanelli Junior e pela aluna de Iniciação Científica Angélica Romão Carvalho. Hidrolisado proteico de soro de leite bovino e torta de linhaça foram os materiais obtidos, após uma série de operações que envolveram filtração com caulim, diálise, hidrólise enzimática, liofilização, etc., após as quais foram utilizados neste trabalho como ligantes de origem natural. Os metais de transição cobre, ferro, cobalto, zinco, paládio, platina e prata foram utilizados nas reações de complexação com os hidrolisados para obtenção de complexos metálicos, através do uso de diferentes rotas sintéticas (convencional, micro-ondas, hidrotérmica, difusão) e parâmetros experimentais (pH, solvente, natureza do precursor, etc.). A escolha dos íons metálicos baseou-se no interesse em preparar compostos que apresentassem ao mesmo tempo alta biodisponibilidade, baixa citotoxicidade e diversas aplicações biológicas. O uso do cobalto deveu-se à reconhecida propriedade que os micro-organismos do sistema digestório dos ruminantes apresenta de sintetizar a vitamina B12 e, portanto, os compostos desse metal podem ser usados em rações visando um melhor desenvolvimento do animal. O ferro, conhecidamente, é um importante metal para os seres humanos, estando presente na hemoglobina, sendo assim, também consiste em uma substância nutracêutica de relevado interesse. À propósito, cabe salientar que os compostos de ferro (III) obtidos nesse trabalho serão objeto de avaliação do uso como suplemento alimentar, em colaboração com o Departamento de...

Drag force in a strongly coupled anisotropic plasma

We calculate the drag force experienced by an in finitely massive quark propagating at constant velocity through an anisotropic, strongly coupled N = 4 plasma by means of its gravity dual. We find that the gluon cloud trailing behind the quark is generally misaligned with the quark velocity, and that the latter is also misaligned with the force. The drag coefficient mu can be larger or smaller than the corresponding isotropic value depending on the velocity and the direction of motion. In the ultra-relativistic limit we find that generically mu proportional to p. We discuss the conditions under which this behaviour may extend to more general situations.

Jet quenching in a strongly coupled anisotropic plasma

The jet quenching parameter of an anisotropic plasma depends on the relative orientation between the anisotropic direction, the direction of motion of the parton, and the direction along which the momentum broadening is measured. We calculate the jet quenching parameter of an anisotropic, strongly coupled N = 4 plasma by means of its gravity dual. We present the results for arbitrary orientations and arbitrary values of the anisotropy. The anisotropic value can be larger or smaller than the isotropic one, and this depends on whether the comparison is made at equal temperatures or at equal entropy densities. We compare our results to analogous calculations for the real-world quark-gluon plasma and find agreement in some cases and disagreement in others.

Rice husk derived waste materials as partial cement replacement in lightweight concrete

In this study rice husk ash (RHA) and broiler bed ash from rice husk (BBA), two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL) and two other types with 10% cement replacement with, respectively, RHA and BBA. All types of similar lightweight concrete were prepared to present the same workability by adjusting the amount of superplasticizer. Properties of concrete investigated were compressive and flexural strength at different ages, absorption by capillarity, resistivity and resistance to chloride ion penetration (CTH method) and accelerated carbonation. Test results obtained for 10% cement replacement level in lightweight concrete indicate that although the addition of BBA conducted to lower performance in terms of the degradation indicative tests, RHA led to the enhancement of mechanical properties, especially early strength and also fast ageing related results, further contributing to sustainable construction with energy saver lightweight concrete.

CHARACTERIZATION AND CLASSIFICATION OF SOILS IN THE TAQUARI RIVER BASIN - PANTANAL REGION, STATE OF MATO GROSSO DO SUL, BRAZIL

Among the soils in the Mato Grosso do Sul, stand out in the Pantanal biome, the Spodosols. Despite being recorded in considerable extensions, few studies aiming to characterize and classify these soils were performed. The purpose of this study was to characterize and classify soils in three areas of two physiographic types in the Taquari river basin: bay and flooded fields. Two trenches were opened in the bay area (P1 and P2) and two in the flooded field (P3 and P4). The third area (saline) with high sodium levels was sampled for further studies. In the soils in both areas the sand fraction was predominant and the texture from sand to sandy loam, with the main constituent quartz. In the bay area, the soil organic carbon in the surface layer (P1) was (OC) > 80 g kg(-1), being diagnosed as Histic epipedon. In the other profiles the surface horizons had low OC levels which, associated with other properties, classified them as Ochric epipedons. In the soils of the bay area (P1 and P2), the pH ranged from 5.0 to 7.5, associated with dominance of Ca2+ and Mg2+, with base saturation above 50 % in some horizons. In the flooded fields (P3 and P4) the soil pH ranged from 4.9 to 5.9, H+ contents were high in the surface horizons (0.8-10.5 cmol(c) kg(-1)), Ca2+ and Mg-2 contents ranged from 0.4 to 0.8 cmol(c) kg(-1) and base saturation was < 50 %. In the soils of the bay area (P1 and P2) iron was accumulated (extracted by dithionite - Fed) and OC in the spodic horizon; in the P3 and P4 soils only Fed was accumulated (in the subsurface layers). According to the criteria adopted by the Brazilian System of Soil Classification (SiBCS) at the subgroup level, the soils were classified as: P1: Organic Hydromorphic Ferrohumiluvic Spodosol. P2: Typical Orthic Ferrohumiluvic Spodosol. P3: Typical Hydromorphic Ferroluvic Spodosol. P4: Arenic Orthic Ferroluvic Spodosol.

Temporal evolution of tubular initial conditions and their influence on two-particle correlations in relativistic nuclear collisions

Relativistic nuclear collisions data on two-particle correlations exhibit structures as function of relative azimuthal angle and rapidity. A unified description of these near-side and away-side structures is proposed for low to moderate transverse momentum. It is based on the combined effect of tubular initial conditions and hydrodynamical expansion. Contrary to expectations, the hydrodynamics solution shows that the high-energy density tubes (leftover from the initial particle interactions) give rise to particle emission in two directions and this is what leads to the various structures. This description is sensitive to some of the initial tube parameters and may provide a probe of the strong interaction. This explanation is compared with an alternative one where some triangularity in the initial conditions is assumed. A possible experimental test is suggested. (C) 2012 Elsevier B.V. All rights reserved.

Monitorização de eletrólitos urinários em pacientes críticos: estudo preliminar observacional

OBJETIVO: Sobreviventes e não sobreviventes da unidade de terapia intensiva apresentam perfis ácido-básicos distintos. A regulação renal de eletrólitos urinários e a diferença de íons fortes urinários têm papéis principais na homeostase ácido- básica. O objetivo deste estudo foi avaliar a potencial utilidade da mensuração diária dos eletrólitos urinários na monitorização ácido-básica e da função renal. MÉTODOS: Foram registrados, prospectivamente e diariamente, parâmetros ácido-básicos plasmáticos e marcadores tradicionais da função renal, em paralelo à medição dos eletrólitos urinários em pacientes com sonda vesical internados na unidade de terapia intensiva. Os pacientes que permaneceram na unidade de terapia intensiva com sonda vesical por pelo menos 4 dias foram incluídos neste estudo. RESULTADOS: Dos 50 pacientes incluídos neste estudo, 22% vieram a óbito durante a internação na unidade de terapia intensiva. A incidência de lesão renal aguda foi significativamente maior nos não sobreviventes, durante os 4 dias de observação (64% versus 18% em sobreviventes). O cloreto e o sódio urinário foram mais baixos, e a diferença de íons fortes urinários mais alta, no 1º dia, em pacientes que desenvolveram lesão renal aguda tanto nos sobreviventes como nos não sobreviventes. Ambos os grupos tiveram débito urinário semelhante, embora os não sobreviventes tenham apresentado diferença de íons fortes urinários persistentemente mais alta durante o período de observação. Os sobreviventes apresentaram melhoria progressiva no perfil metabólico ácido-básico devido ao aumento, no plasma, da diferença de íons fortes e à diminuição dos ácidos fracos. Essas mudanças foram concomitantes à diminuição da diferença de íons fortes urinários. Com relação aos não sobreviventes, os parâmetros ácido-básicos não tiveram alteração significativa durante o seguimento. CONCLUSÃO: A avaliação diária dos eletrólitos urinários e da diferença de íons fortes urinários é útil para a monitorização ácido-básica e da função renal em pacientes críticos, tendo perfis distintos entre sobreviventes e não sobreviventes na unidade de terapia intensiva.

Estudo eletroquímico da recuperação de metais de pilhas e de baterias descartadas após o uso

O objetivo da pesquisa é recuperar os principais metais presentes em um lote com uma mistura de diversos tipos de pilhas e de baterias descartadas após o uso, lote obtido em um posto de coleta. Para esse estudo, o resíduo das pilhas e das baterias foi moído, reduzido em forno elétrico, submetido à separação magnética e lixiviado. A composição química, após a lixiviação, foi reproduzida em uma solução sintética, que foi submetida à extração por solventes e reextração sendo que as soluções obtidas, após as reextrações, foram utilizadas como eletrólitos. Manganês, cobre, cobalto e níquel são recuperados na forma metálica após um tratamento que inclui as etapas pirometalúrgica, hidrometalúrgica e eletroquímica. Estudos anteriores definiram os parâmetros das etapas pirometalúrgica, lixiviação e extração por solventes que proporcionaram separação mais seletiva dos íons metálicos que se pretende recuperar. A contribuição do presente estudo é encontrar um processo que trate de todos os tipos de pilhas e de baterias juntos e recuperar seus metais mais importantes, evitando, assim, a etapa de separação prévia das baterias. Os filmes foram analisados quanto à sua espessura e composição.

Surface modification by metal ion implantation forming metallic nanoparticles in insulating matrix.

There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We investigated nanocomposites produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. During the implantation, the excess of metal atom concentration above the solubility limit leads to nucleation and growth of metal nanoparticles, driven by the temperature and temperature gradients within the implanted sample including the beam-induced thermal characteristics. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), that can be estimated by computer simulation using the TRIDYN. This is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study suggests that the nanoparticles form a bidimentional array buried few nanometers below the substrate surface. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples showed the metallic nanoparticles formed in the insulating matrix. The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted. These experimental results were compared with a model based on percolation theory, in which electron transport through the composite is explained by conduction through a random resistor network formed by the metallic nanoparticles. Excellent agreement was found between the experimental results and the predictions of the theory. It was possible to conclude, in all cases, that the conductivity process is due only to percolation (when the conducting elements are in geometric contact) and that the contribution from tunneling conduction is negligible.

Investigation of the interaction of alkali ions with surfactant head groups for the formation of lyotropic biaxial nematic phase via optical birefringence measurements.

Lyotropic liquid crystals exhibiting nematic phases were obtained from the mixtures potassium laurate/alkali sulfate salts (M2SO4)/1-undecanol (UndeOH)/water and sodium dodecyl sulfate (SDS)/M2SO4/1-dodecanol (DDeOH)/water, where M2SO4 represents the alkali sulfate salts being Li2SO4, Na2SO4, K2SO4, Rb2SO4 or Cs2SO4. The birefringences measurements were performed via laser conoscopy. Our results indicated that cosmotropic and chaotropic behaviors of both ions and head groups are very important to obtain lyotropic biaxial nematic phase. To obtain the biaxial nematic phase, surfactant head group and ion present in lyotropic mixture have relatively opposite behavior, e.g. one more cosmotropic (more chaotropic) other less cosmotropic (less chaotropic) or vice versa.

Single meson production in proton diffraction at 190 GeV/c at COMPASS

The quark model successfully describes all ground state bary-ons as members of $SU(N)$ flavour multiplets. For excited baryon states the situation is totally different. There are much less states found in the experiment than predicted in most theoretical calculations. This fact has been known for a long time as the 'missing resonance problem'. In addition, many states found in experiments are only poorly measured up to now. Therefore, further experimental efforts are needed to clarify the situation.rnrnAt mbox{COMPASS}, reactions of a $190uskgigaeVperclight$ hadron beam impinging on a liquid hydrogen target are investigated.rnThe hadron beam contains different species of particles ($pi$, $K$, $p$). To distinguish these particles, two Cherenkov detectors are used. In this thesis, a new method for the identification of particles from the detector information is developed. This method is based on statistical approaches and allows a better kaon identification efficiency with a similar purity compared to the method, which was used before.rnrnThe reaction $pprightarrow ppX$ with $X=(pi^0,~eta,~omega,~phi)$ is used to study different production mechanisms. A previous analysis of $omega$ and $phi$ mesons is extended to pseudoscalar mesons. As the resonance contributions in $peta$ are smaller than in $ppi^0$ a different behaviour of these two final states is expected as a function of kinematic variables. The investigation of these differences allows to study different production mechanisms and to estimate the size of the resonant contribution in the different channels.rnrnIn addition, the channel $pprightarrow ppX$ allows to study baryon resonances in the $pX$ system.rnIn the mbox{COMPASS} energy regime, the reaction is dominated by Pomeron exchange. As a Pomeron carries vacuum quantum numbers, no isospin is transferred between the target proton and the beam proton. Therefore, the $pX$ final state has isospin $textstylefrac{1}{2}$ and all baryon resonances in this channel are $N^ast$ baryons. This offers the opportunity to do spectroscopy without taking $Delta$ resonances into account. rnrnTo disentangle the contributions of different resonances a partial wave analysis (PWA) is used. Different resonances have different spin and parity $J^parity$, which results in different angular distributions of the decay particles. These angular distributions can be calculated from models and then be fitted to the data. From the fit the contributions of the single resonances as well as resonance parameters -- namely the mass and the width -- can be extracted. In this thesis, two different approaches for a partial wave analysis of the reaction $pprightarrow pppi^0$ are developed and tested.

ESPEN Guidelines on Enteral Nutrition: Geriatrics

Nutritional intake is often compromised in elderly, multimorbid patients. Enteral nutrition (EN) by means of oral nutritional supplements (ONS) and tube feeding (TF) offers the possibility to increase or to insure nutrient intake in case of insufficient oral food intake. The present guideline is intended to give evidence-based recommendations for the use of ONS and TF in geriatric patients. It was developed by an interdisciplinary expert group in accordance with officially accepted standards and is based on all relevant publications since 1985. The guideline was discussed and accepted in a consensus conference. EN by means of ONS is recommended for geriatric patients at nutritional risk, in case of multimorbidity and frailty, and following orthopaedic-surgical procedures. In elderly people at risk of undernutrition ONS improve nutritional status and reduce mortality. After orthopaedic-surgery ONS reduce unfavourable outcome. TF is clearly indicated in patients with neurologic dysphagia. In contrast, TF is not indicated in final disease states, including final dementia, and in order to facilitate patient care. Altogether, it is strongly recommended not to wait until severe undernutrition has developed, but to start EN therapy early, as soon as a nutritional risk becomes apparent.

Learner preferences regarding integrating, sequencing and aligning virtual patients with other activities in the undergraduate medical curriculum: A focus group study

CONTEXT: E-learning resources, such as virtual patients (VPs), can be more effective when they are integrated in the curriculum. To gain insights that can inform guidelines for the curricular integration of VPs, we explored students' perceptions of scenarios with integrated and non-integrated VPs aimed at promoting clinical reasoning skills. METHODS: During their paediatric clerkship, 116 fifth-year medical students were given at least ten VPs embedded in eight integrated scenarios and as non-integrated add-ons. The scenarios differed in the sequencing and alignment of VPs and related educational activities, tutor involvement, number of VPs, relevance to assessment and involvement of real patients. We sought students' perceptions on the VP scenarios in focus group interviews with eight groups of 4-7 randomly selected students (n = 39). The interviews were recorded, transcribed and analysed qualitatively. RESULTS: The analysis resulted in six themes reflecting students' perceptions of important features for effective curricular integration of VPs: (i) continuous and stable online access, (ii) increasing complexity, adapted to students' knowledge, (iii) VP-related workload offset by elimination of other activities, (iv) optimal sequencing (e.g.: lecture--1 to 2 VP(s)--tutor-led small group discussion--real patient) and (V) optimal alignment of VPs and educational activities, (vi) inclusion of VP topics in assessment. CONCLUSIONS: The themes appear to offer starting points for the development of a framework to guide the curricular integration of VPs. Their impact needs to be confirmed by studies using quantitative controlled designs.

Home artificial nutrition in Switzerland: an epidemiological survey from 2005 to 2009.

BACKGROUND AND AIMS Home artificial nutrition (HAN), including oral nutritional supplements (ONS) and enteral (HEN) and parenteral (HPN) nutrition, is an established, important treatment for malnourished patients. The aim of this study was to analyze the epidemiological data of patients on HAN in Switzerland. METHODS This retrospective study recorded all new cases of HAN in Switzerland from January 2005 to December 2009. RESULTS A total of 12,917 cases were recorded: 6,731 (52%) males and 6,186 (48%) females, with a mean age of 65.0 ± 17.6 years. The number of patients on ONS was 7,827 (57.4%), on HEN 3,966 (39.4%) and on HPN 433 (3.2%). The most common underlying disease category was neoplasms (6,519, 50.7%). The number of patients on ONS increased from 57.0% (n = 1,252) to 60.8% (n = 2,039), and on HPN from 2.1% (n = 45) to 4.0% (n = 134) between 2005 and 2009. CONCLUSIONS This first analysis of the large-scale Swiss registry of HAN shows that approximately half of the patients received ONS, whereas HPN was rarely delivered. The frequency of ONS and HPN increased from the year 2005 to 2009. In accordance with previous European studies, malignant tumors were by far the most frequent indication for HAN.