Influence of polymerization on the synthesis of SrTiO3: Part II. Particle and agglomerate morphologies

Morphologies of SrTiO3 particles and agglomerates synthesized by the traditional Pechini route and by the polymer precipitation route were characterized by the nitrogen adsorption/desorption technique and by transmission electron microscopy (TEM). A cluster structure of nanometric particles forming large agglomerates which are broken during pressing followed by cluster rearrangement was observed. The mean particle size is larger for SrTiO3 obtained by the Pechini route and is related to the precursor thermal decomposition and particle growth during calcination. The particle growth is controlled by neck growth among particles and further motion of the particle boundary. © 1995.

Potencial tóxico dos alginatos para uso odontológico

Alginate or irreversible hydrocolloid is one the most accepted and frequently employed impression materials in dental practice. Substances like zinc, cadmium, lead silicate and fluorides, which are included in several alginate brands with the aim of improving their physical, chemical and mechanical properties, are a source of serious concern as regards their toxicity. Some brands of alginate have been reported to contain potentially toxic fluorides and metals such as cadmium, lead and zinc silicates, either singly or combined. Consequently, special care should be taken while preparing of these materials. It is necessary to monitor potentially toxic chemicals and metals in the alginates continually to avoid contamination of dental professionals and patients. In this review, alginates used in dentistry are analyzed for potential toxicity.

Non-labile plant C contributes to long-lasting macroaggregation of an Oxisol

Decomposition of plant material influences soil aggregation dynamics in ways that are still poorly understood, especially for Oxisols, in which oxides are believed to play a dominant role. In an incubation experiment, we investigated (i) the effect of plant material addition from selected monocot and dicot species on soil organic C (SOC), carbohydrate composition, fungal and total microbial biomass, and aggregation of an Oxisol; and (ii) the relationship among these properties and C mineralization patterns. The experiment was carried out at 25 °C for 180 d after addition of 11 plant materials (4 g C kg-1 soil) and a control (no plant material added). Mineralization of C during the incubation was described considering two pools of C (labile and non-labile) using a first-order plus linear fitting. Compared to the control, corn materials showed larger pentose input, greater mineralization rates for the non-labile C pool (k), greater soil pentose content (xylose + arabinose) and larger mean weight diameter of soil water-stable aggregates at 180 d of incubation. These effects were independent of changes in SOC content, suggesting that total C accrual and macroaggregation may be decoupled processes in this Oxisol. Our results support the hypothesis that the non-labile plant C pool contributes to the long-lasting stability of macroaggregates of this Oxisol and that this effect is mediated by plant and soil pentoses. We propose that plant pentose content and the decomposition rate of the slow pool (k) are useful parameters for the prediction of plant effects on aggregation dynamics of Oxisols and the selection of soil conservation practices. © 2012.

Associations of vitamin D deficiency with postoperative gait and mortality among patients with fractures of the proximal femur

To assess whether serum vitamin D concentration is associated with gait status and mortality among patients with fractures of the proximal femur, six months after suffering the fracture. Consecutive patients aged ≥65 years with fractures of the proximal femur, who were admitted to the orthopedics and traumatology ward of our service between January and December 2011, were prospectively evaluated. Clinical, radiological, epidemiological and laboratory analyses were performed, including vitamin D. The patients underwent surgery and were followed up as outpatients, with return visits 15, 30, 60 and 180 days after discharge, at which the outcomes of gait and mortality were evaluated. Eighty-eight patients were evaluated. Two of them were excluded because they presented oncological fractures. Thus, 86 patients of mean age 80.2 ± 7.3 years were studied. In relation to serum vitamin D, the mean was 27.8 ± 14.5 ng/mL, and 33.7% of the patients presented deficiency of this vitamin. In relation to gait, univariate and multivariate logistic regression showed that vitamin D deficiency was not associated with gait recovery, even after adjustment for gender, age and type of fracture (OR: 1.463; 95% CI: 0.524-4.088; p = 0.469). Regarding mortality, Cox regression analysis showed that vitamin D deficiency was not related to its occurrence within six months, even in multivariate analysis (HR: 0.627; 95% CI: 0.180-2.191; p = 0.465). Serum vitamin D concentration was not related to gait status and/or mortality among patients with fractures of the proximal femur, six months after suffering the fracture.

An electrochemical gas sensor based on paper supported room temperature ionic liquids

A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs as well as their easy immobilization into a porous and inexpensive supporting material such as paper. Moreover, thanks to a careful control of the preparation procedure, a very close contact between the RTIL and electrode material can be achieved so as to allow gaseous analytes to undergo charge transfer just as soon as they reach the three-phase sites where the electrode material, paper supported RTIL and gas phase meet. Thus, the adverse effect on recorded currents of slow steps such as analyte diffusion and dissolution in a solvent is avoided. To evaluate the performance of this device, it was used as a wall-jet amperometric detector for flow injection analysis of 1-butanethiol vapours, adopted as the model gaseous analyte, present in headspace samples in equilibrium with aqueous solutions at controlled concentrations. With this purpose, the RTIL soaked paper electrochemical detector (RTIL-PED) was assembled by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide as the wicking RTIL and printing the working electrode with carbon ink doped with cobalt(II) phthalocyanine, to profit from its ability to electrocatalyze thiol oxidation. The results obtained were quite satisfactory (detection limit: 0.5 mu M; dynamic range: 2-200 mu M, both referring to solution concentrations; correlation coefficient: 0.998; repeatability: +/- 7% RSD; long-term stability: 9%), thus suggesting the possible use of this device for manifold applications.

Tricarbonyltechnetium(I) and -rhenium(I) complexes with N '-thiocarbamoylpicolylbenzamidines

N,N-Dialkylamino(thiocarbonyl)-N'-picolylbenzamidines react with (NEt4)(2)[M(CO)(3)X-3] (M = Re, X = Br: M = Tc, X = Cl) under formation of neutral [M(CO)(3)L] complexes in high yields. The monoanionic NNS ligands bind in a facial coordination mode and can readily be modified at the (CS)(NRR2)-R-1 moiety. The complexes [Tc-99(CO)(3)(L-PyMor)] and]Re(CO)(3)(L)] (L = L-PyMor, L-PyEt) were characterized by X-ray diffraction. Reactions of [Tc-99m(CO)(3)(H2O)(3)](+) with the N'-thiocarbamoylpicolylbenzamidines give the corresponding Tc-99m complexes. The ester group in HLPyCOOEr allows linkage between biomolecules and the metal core. (C) 2012 Elsevier Ltd. All rights reserved.

Colistin Resistance in Escherichia coli and Salmonella enterica Strains Isolated from Swine in Brazil

Reports about acquired resistance to colistin in different bacteria species are increasing, including E. coli of animal origin, but reports of resistance in wild S. enterica of different serotypes from swine are not found in the literature. Results obtained with one hundred and twenty-six E. coli strains from diseased swine and one hundred and twenty-four S. enterica strains from diseased and carrier swine showed a frequency of 6.3% and 21% of colistin-resistant strains, respectively. When comparing the disk diffusion test with the agar dilution test to evaluate the strains, it was confirmed that the disk diffusion test is not recommended to evaluate colistin resistance as described previously. The colistin MIC 90 and MIC 50 values obtained to E. coli were 0.25 mu g/mL and 0.5 mu g/mL, the MIC 90 and MIC 50 to S. enterica were 1 mu g/mL and 8 mu g/mL. Considering the importance of colistin in control of nosocomial human infections with Gram-negative multiresistant bacteria, and the large use of this drug in animal production, the colistin resistance prevalence in enterobacteriaceae of animal origin must be monitored more closely.

Probing the cosmic distance-duality relation with the Sunyaev-Zel'dovich effect, X-ray observations and supernovae Ia

Context. The angular diameter distances toward galaxy clusters can be determined with measurements of Sunyaev-Zel'dovich effect and X-ray surface brightness combined with the validity of the distance-duality relation, D-L(z)(1 + z)(2)/D-A(z) = 1, where D-L(z) and D-A(z) are, respectively, the luminosity and angular diameter distances. This combination enables us to probe galaxy cluster physics or even to test the validity of the distance-duality relation itself. Aims. We explore these possibilities based on two different, but complementary approaches. Firstly, in order to constrain the possible galaxy cluster morphologies, the validity of the distance-duality relation (DD relation) is assumed in the Lambda CDM framework (WMAP7). Secondly, by adopting a cosmological-model-independent test, we directly confront the angular diameters from galaxy clusters with two supernovae Ia (SNe Ia) subsamples (carefully chosen to coincide with the cluster positions). The influence of the different SNe Ia light-curve fitters in the previous analysis are also discussed. Methods. We assumed that eta is a function of the redshift parametrized by two different relations: eta(z) = 1 +eta(0)z, and eta(z) = 1 + eta(0)z/(1 + z), where eta(0) is a constant parameter quantifying the possible departure from the strict validity of the DD relation. In order to determine the probability density function (PDF) of eta(0), we considered the angular diameter distances from galaxy clusters recently studied by two different groups by assuming elliptical and spherical isothermal beta models and spherical non-isothermal beta model. The strict validity of the DD relation will occur only if the maximum value of eta(0) PDF is centered on eta(0) = 0. Results. For both approaches we find that the elliptical beta model agrees with the distance-duality relation, whereas the non-isothermal spherical description is, in the best scenario, only marginally compatible. We find that the two-light curve fitters (SALT2 and MLCS2K2) present a statistically significant conflict, and a joint analysis involving the different approaches suggests that clusters are endowed with an elliptical geometry as previously assumed. Conclusions. The statistical analysis presented here provides new evidence that the true geometry of clusters is elliptical. In principle, it is remarkable that a local property such as the geometry of galaxy clusters might be constrained by a global argument like the one provided by the cosmological distance-duality relation.

Amplification of the flgE gene provides evidence for the existence of a Brazilian borreliosis

INTRODUCTION: The symptoms of Brazilian borreliosis resemble the clinical manifestations of Lyme disease (LD). However, there are differences between the two in terms of epidemiological and laboratory findings. Primers usually employed to diagnose LD have failed to detect Borrelia strains in Brazil. OBJECTIVE: We aimed to identify the Brazilian Borrelia using a conserved gene that synthesizes the flagellar hook (flgE) of Borrelia burgdorferi sensu lato. METHOD: Three patients presenting with erythema migrans and positive epidemiological histories were recruited for the study. Blood samples were collected, and the DNA was extracted by commercial kits. RESULTS: The gene flgE was amplified from DNA of all selected patients. Upon sequencing, these positive samples revealed 99% homology to B. burgdorferi flgE. CONCLUSION: These results support the existence of borreliosis in Brazil. However, it is unclear whether this borreliosis is caused by a genetically modified B. burgdorferi sensu stricto or by a new species of Borrelia spp.

Experimental Evaluation of Immediate Recanalization Effect and Recanalization Efficacy of a New Thrombus Retriever for Acute Stroke Treatment In Vivo

BACKGROUND AND PURPOSE: Currently, several new stent retriever devices for acute stroke treatment are under development and early clinical evaluation. Preclinical testing under standardized conditions is an important first step to evaluate the technical performance and potential of these devices. The aim of this study was to evaluate the immediate recanalization effect, recanalization efficacy, thrombus-device interaction, and safety of a new stent retriever intended for thrombectomy in patients with acute stroke. MATERIAL AND METHODS: The pREset thrombectomy device (4 × 20 mm) was evaluated in 16 vessel occlusions in an established swine model. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. Flow-restoration effect immediately after deployment and after 5-minute embedding time before retrieval, recanalization rate after retrieval, thromboembolic events, and complications were assessed. High-resolution FPCT was performed to illustrate thrombus-device interaction during the embedding time. RESULTS: Immediate flow restoration was achieved in 75% of occlusions. An increase or stable percentage of recanalizations during embedding time before retrieval was seen in 56.3%; a decrease, in 12.5%; reocclusion of a previously recanalized vessel, in 18.8%; and no recanalization effect at all, in 12.5%. Complete recanalization (TICI 3) after retrieval was achieved in 93.8%; partial recanalization (TICI 2b), in 6.2%. No distal thromboembolic events were observed. High-resolution FPCT illustrated entrapment of the thrombus between the stent struts and compression against the contralateral vessel wall, leading to partial flow restoration. During retrieval, the thrombus was retained in a straight position within the stent struts. CONCLUSIONS: In this experimental study, the pREset thrombus retriever showed a high recanalization rate in vivo. High-resolution FPCT allows detailed illustration of the thrombus-device interaction during embedding time and is advocated as an add-on tool to the animal model used in this study.

Kostenorientiertes Controlling von E-Learning-Plattformen mit dem TCO-Konzept

Zur administrativen Unterstützung von Lehr- und Lernprozessen werden E-Learning-Plattformen eingesetzt, die auf der Grundlage des Internet Funktionen zur Distribution von Lehr- und Lernmaterialien und zur Kommunikation zwischen Lehrenden und Lernenden anbieten. Zahlreiche wissenschaftliche Beiträge und Marktstudien beschäftigen sich mit der multikriteriellen Evaluation dieser Softwareprodukte zur informatorischen Fundierung strategischer Investitionsentscheidungen. Demgegenüber werden Instrumente zum kostenorientierten Controlling von E-Learning-Plattformen allenfalls marginal thematisiert. Dieser Beitrag greift daher das Konzept der Total Cost of Ownership (TCO) auf, das einen methodischen Ansatzpunkt zur Schaffung von Kostentransparenz von E-Learning-Plattformen bildet. Aufbauend auf den konzeptionellen Grundlagen werden Problembereiche und Anwendungspotenziale für das kostenorientierte Controlling von LMS identifiziert. Zur softwaregestützten Konstruktion und Analyse von TCO-Modellen wird das Open Source-Werkzeug TCO-Tool eingeführt und seine Anwendung anhand eines synthetischen Fallbeispiels erörtert. Abschließend erfolgt die Identifikation weiterführender Entwicklungsperspektiven des TCO-Konzepts im Kontext des E-Learning. Die dargestellte Thematik ist nicht nur von theoretischem Interesse, sondern adressiert auch den steigenden Bedarf von Akteuren aus der Bildungspraxis nach Instrumenten zur informatorischen Fundierung von Investitions- und Desinvestitionsentscheidungen im Umfeld des E-Learning.

Changing the Face of Traditional Education

At large, research universities, a common approach for teaching hundreds of undergraduate students at one time is the traditional, large, lecture-based course. Trends indicate that over the next decade there will be an increase in the number of large, campus courses being offered as well as larger enrollments in courses currently offered. As universities investigate alternative means to accommodate more students and their learning needs, Web-based instruction provides an attractive delivery mode for teaching large, on-campus courses. This article explores a theoretical approach regarding how Web-based instruction can be designed and developed to provide quality education for traditional, on-campus, undergraduate students. The academic debate over the merit of Web-based instruction for traditional, on-campus students has not been resolved. This study identifies and discusses instructional design theory for adapting a large, lecture-based course to the Web.

E-Learning 2.0 in hydraulic engineering education

In this contribution the experiences with e-Learning 2.0 applications by using a Wiki for the education in hydraulic engineering are shown. Up to now important information for the students has been prepared by the instructor. For this project the students were asked to collaborate and search on their own for the information they needed. Therefore a Wiki-system was used. For the engineering practice a self dependent realisation of tasks is an important requirement which students should be prepared for. With the help of online communication there should be shown the possibilities for students for working together in an interdisciplinary team. The positive experiences as well as the results of the evaluation of this project plead for a continuation of the application of e-Learning 2.0 for education. The comparison of results of tests without using Wiki and with using Wiki shows a qualitative tendency of better marks. In this contribution we present the application of Wiki in hydraulic engineering but the results can also be used for other engineering disciplines.