Link-based approach to study scientific software usage: the case of VOSviewer

Scientometrics - Scientific software is a fundamental player in modern science, participating in all stages of scientific knowledge production. Software occasionally supports the development of...     

Exploring Epigenetic Marks by Analysis of Noncovalent Interactions

Epigenetic marks are modest chemical modifications on DNA and histone proteins that regulate the activation or silencing of genes through modulation of the intermolecular interactions between the DNA strands and the protein machinery. The process is complex and not always well understood. One of the systems studied in greater detail is the epigenetic mark on H3K9: lysine 9 of histone 3. The degree of methylation or acetylation of this histone is linked to silencing or activation of the corresponding gene, but it is not clear which effect each mark has in gene expression. We shed light on this particular methylation process by using density functional theory (DFT) calculations. First, we built a model consisting of a DNA double strand containing three base pairs and a sequence of three amino acids of the histone's tail. Then, we computed the modulation introduced into the intermolecular interactions by each epigenetic modification: from mono- to trimethylation and acetylation. The calculations show that whereas acetylation and trimethylation result in a reduction of the DNA-peptide interaction; non-, mono-, and dimethylation increase the intermolecular interactions. Such observations compare well with the findings reported in the literature, and highlight the correlation between the balance of intermolecular forces and biological properties, simultaneously advancing quantum-mechanical studies of large biochemical systems at molecular level through the use of DFT methods.     

Studying the characteristics of scientific communities using individual-level bibliometrics: the case of Big Data research

Scientometrics - Unlike most bibliometric studies focusing on publications, taking Big Data research as a case study, we introduce a novel bibliometric approach to unfold the status of a given...     

Friction Hydro-Pillar Processing and Tungsten Inert Gas Welding of a Duplex Stainless Steel

This work presents friction hydro-pillar processing (FHPP) and tungsten inert gas (TIG) welding of SAF2205 duplex stainless steel. Weld microstructural and mechanical characterisation were carried out based on the standards (DNV-RP-F112 and DNV-OS-F101). Therefore, optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction were used. In addition, mechanical properties were evaluated by microhardness measurements. Furthermore, the joining processes were thermodynamically simulated for confirmation of the expected phases in each welding method. It was possible to verify the phases developed after the experimental welding (FHPP and TIG) as well as the ones obtained in the thermodynamic analyses. Finally, it was noted that FHPP promoted mechanical and metallurgical features requested by the standards.     

Detection of helmets on motorcyclists

Multimedia Tools and Applications - The use of motorcycle accidents has rapidly increased. Although the helmet is the main safety equipment of motorcyclists, many drivers do not use it. This paper...     

Generation of Amyloid-β Peptides by γ-Secretase

γ-Secretase is a four-component membrane-embedded aspartyl protease involved in the final cleavage step of the amyloid precursor protein (APP) to generate the amyloid-β (Aβ) peptide. Different amino-acid lengths of Aβ peptide can be produced by this enzyme, of which the oligomerization and aberrant accumulation of the product containing 42 amino acids (Aβ42) has been associated with the development and formation of amyloid-β plaques in the brain of Alzheimer's disease (AD) patients. Herein, we review some of the most important topics associated with the structure and activity of γ-secretase and the factors that alter the substrate cleavage pattern, critical to the formation of the different isoforms of the amyloid-β peptides.     

A Moving Horizon Estimator for processes with multi-rate measurements: A Nonlinear Programming sensitivity approach

Moving Horizon Estimation (MHE) provides a framework that allows one to incorporate both frequent and infrequent observations easily because it uses a window of past measurements, where the slower ones can be introduced as they become available. Also, MHE allows for the use of constraints on the state estimates, which improves the performance of the estimator.Here we propose the use of a variable structure MHE that can handle multi-rate measurements. Furthermore, we propose a novel strategy for updating the smoothed covariance matrix of the arrival cost based on Nonlinear Programming (NLP) sensitivity. For this we show the relationship that exists between the covariance and the reduced Hessian of the NLP. Moreover, we propose a fast strategy for extracting the reduced Hessian information directly from the linearized optimality conditions used in Interior Point solvers such as IPOPT. The proposed methodology is illustrated using benchmark examples from the literature.     

Evaluation of the influence of post welding heat treatments on microstructure and mechanical properties of API 5L X70Q weld joints*

Steels that meet the API 5L standard are employed in pipeline construction, and there is considerable interest in those of higher strength, such as grade API 5L X70Q. There have nevertheless been few studies relating to seamless pipes. During installation, the pipes may be welded with covered electrodes (SMAW) and may optionally undergo inductive heating for adjustment to the topography of the terrain, processes that may alter the microstructure of the joints. In this work, welded joints were obtained by the SMAW process, from seamless pipe of grade API 5L X70Q. The joints were submitted to post-weld heat treatments at temperatures of 920 and 600 °C. Tensile, Charpy impact and microhardness tests were carried out, besides metallographic characterization in specimens of base metal and in the joints, as-welded and after the heat treatments. Heat treatment at 920 °C promoted formation of a ferrite/pearlite structure, with consequent reduction in the mechanical strength of the joints to values below those specified for grade X70Q. However, heat treatment at 600 °C proved to be beneficial owing to the reduction of the volume fraction of the martensite/austenite and martensite-austenite-bainite constituents, without significantly reducing the mechanical strength and with a relative gain in impact toughness in the heat-affected zone and in the fusion zone (FZ).     

Effects of tangential microfiltration and pasteurisation on the rheological,microbiological, physico‐chemical and sensory characteristics of sugar cane juice

The aim of this study was to determine the physico‐chemical, microbiological, rheological and sensory characteristics of sugar cane juice with passion fruit pulp (5% w/w) added and which had been submitted to microfiltration and pasteurisation (90 °C/30 s; 95 °C/30 s) processes. The results showed that the juices obtained after the microfiltration and pasteurisation processes had low microbial counts. The microfiltered juice showed a reduction in the soluble solids, acidity and vitamin C content (P = 0.05), while the pasteurised juice showed no change in these parameters (P > 0.05) in relation to the natural sugar cane juice, with the exception of vitamin C, which was not detected after the thermal treatment. In relation to the rheological properties, Newtonian behaviour was observed for both microfiltered and pasteurised juices. The sensory tests on a hedonic scale showed good acceptance of both juices (microfiltered and pasteurised).