Optimization of the investment casting process

Rapid prototyping is an important technique for manufacturing. This work refers to the manufacture of hollow patterns made of polymeric materials by rapid prototyping technologies for its use in the preparation of ceramic molds in the investment casting process. This work is focused on the development of a process for manufacturing patterns different from those that currently exist due to its hollow interior design, allowing its direct use in the fabrication of ceramic molds; avoiding cracking and fracture during the investment casting process, which is an important process for the foundry industry

Optimiranje postupka kalupljenja u ljevačkom procesu

Rapid prototyping is an important technique for manufacturing. This work refers to the manufacture of hollow patterns made of polymeric materials by rapid prototyping technologies for its use in the preparation of ceramic molds in the investment casting process. This work is focused on the development of a process for manufacturing patterns different from those that currently exist due to its hollow interior design, allowing its direct use in the fabrication of ceramic molds; avoiding cracking and fracture during the investment casting process, which is an important process for the foundry industry.Brzo razvijanje prototipa važna je proizvodna tehnika. Ovaj se rad odnosi na proizvodnju šupljih kalupa izrađenih od polimerskih materijala pomoću tehnologija brzog razvijanja prototipa za uporabu u izradi keramičkih modela u postupku kalupljenja ljevačkog procesa. Ovaj rad je usmjeren na razvijanje postupka za proizvodnju kalupa drukčijih od onih kakvi trenutno postoje i to zbog svoje šuplje unutarnje izvedbe čime se omogućava izravna uporaba u izradi keramičkih modela te se izbje gava pucanje i lom tijekom postupka kalupljenja ljevačkog procesa koji predstavlja važan postupak u ljevaoničkoj industriji

Effect of phytoremediated port sediment as an agricultural medium for pomegranate cultivation: Mobility of contaminants in the plant

Although the dredging of ports is a necessary management activity, it generates immense quantities of sediments, that are defined by the European Union as residues. On the other hand, the relevant peat demand for plant cultivation compromises its availability worldwide. In this context, the present work wanted to find an alternative substrate in order to replace and/or reduce the use of peat in agriculture, through the study of the suitability, concerning the exchange of substrate–plant–water pollutants, of the dredged remediated sediments as a fruit-growing media. Forty-five pomegranate trees (Punica granatum L. cv “Purple Queen”) were cultivated in three types of substrates (100% peat as a control, 100% dredged remediated sediments and 50% both mixed). The metal ion content and pesticide residues were analysed in the different plant parts (root, stem, leaves and fruits) and in drainage water. The results showed a limited transfer of pollutants. All the pollutants were below the legal limits, confirming that the dredged sediments could be used as a growing media, alone or mixed with other substrates. Thus, the results point out the need to open a European debate on the reuse and reconsideration of this residue from a circular economy point of view

Learning from sensory predictions for autonomous and adaptive exploration of object shape with a tactile robot

Humans use information from sensory predictions, together with current observations, for the optimal exploration and recognition of their surrounding environment. In this work, two novel adaptive perception strategies are proposed for accurate and fast exploration of object shape with a robotic tactile sensor. These strategies called (1) adaptive weighted prior and (2) adaptive weighted posterior, combine tactile sensory predictions and current sensor observations to autonomously adapt the accuracy and speed of active Bayesian perception in object exploration tasks. Sensory predictions, obtained from a forward model, use a novel Predicted Information Gain method. These predictions are used by the tactile robot to analyse ‘what would have happened’ if certain decisions ‘would have been made’ at previous decision times. The accuracy of predictions is evaluated and controlled by a confidence parameter, to ensure that the adaptive perception strategies rely more on predictions when they are accurate, and more on current sensory observations otherwise. This work is systematically validated with the recognition of angle and position data extracted from the exploration of object shape, using a biomimetic tactile sensor and a robotic platform. The exploration task implements the contour following procedure used by humans to extract object shape with the sense of touch. The validation process is performed with the adaptive weighted strategies and active perception alone. The adaptive approach achieved higher angle accuracy (2.8 deg) over active perception (5 deg). The position accuracy was similar for all perception methods (0.18 mm). The reaction time or number of tactile contacts, needed by the tactile robot to make a decision, was improved by the adaptive perception (1 tap) over active perception (5 taps). The results show that the adaptive perception strategies can enable future robots to adapt their performance, while improving the trade-off between accuracy and reaction time, for tactile exploration, interaction and recognition tasks

Development of a Smart Modular Heat Recovery Unit Adaptable into a Ventilated Façade

This paper presents the designing aspects and first experimental characterization of an adaptable Smart Modular Heat Recovery Unit (SMHRU) developed under the scope of the E2VENT Project. This SMHRU is being designed as a part of an adaptable renovation module for the retrofitting of multi-storey residential building from the 60's, 70's across Europe that embeds the SMHRU and an energy storage system based on a phase change material. This heat recovery unit will be adjustable to be integrated into the ventilated façade cavity, and able to recover heat from ventilation air, preheating the ventilation air in winter and precooling it in summer. This will allow an efficient combination of consumption reduction and acceptable air indoor quality. The first part of the paper presents designing considerations and thermal stationary analysis of the heat recovery unit, which is based on experimental correlations obtained for air-to-air compact offset-strip-fin plate heat exchangers. Secondly CFD analysis of the distributor of the SMHRU is presented. Finally prototype first performance estimation based on experimental results is presented.This work has been developed under the project “E2VENT: Energy Efficient Ventilated Façades” funded by the Horizon 2020 framework of the European Union, Project No. 637261

Crystallization and preliminary X-ray diffraction analysis of levansucrase (LsdA) from Gluconacetobacter diazotrophicus SRT4

The endophytic bacterium Gluconacetobacter diazotrophicus SRT4 secretes a constitutively expressed levansucrase (LsdA; EC 2.4.1.10), which converts sucrose to fructo-oligosaccharides and levan. Fully active LsdA was purified to high homogeneity by non-denaturing reversed-phase HPLC and was crystallized at room temperature by the hanging-drop vapour-diffusion method using ammonium sulfate and ethanol as precipitants. The crystals are extremely sensitive, but native data have been collected to 2.5 A under cryogenic conditions using synchrotron radiation. LsdA crystals belong to the orthorhombic space group P22(1)2(1) or P2(1)2(1)2, with unit-cell parameters a = 53.80, b = 119.39, c = 215.10 A

Ion channels and neuronal excitability in polyglutamine neurodegenerative diseases

Abstract Polyglutamine (polyQ) diseases are a family composed of nine neurodegenerative inherited disorders (NDDs) caused by pathological expansions of cytosine-adenine-guanine (CAG) trinucleotide repeats which encode a polyQ tract in the corresponding proteins. CAG polyQ repeat expansions produce neurodegeneration via multiple downstream mechanisms; among those the neuronal activity underlying the ion channels is affected directly by specific channelopathies or indirectly by secondary dysregulation. In both cases, the altered excitability underlies to gain- or loss-of-function pathological effects. Here we summarize the repertoire of ion channels in polyQ NDDs emphasizing the biophysical features of neuronal excitability and their pathogenic role. The aim of this review is to point out the value of a deeper understanding of those functional mechanisms and processes as crucial elements for the designing and targeting of novel therapeutic avenues

Evaluación financiera de producción de pejelagarto (atractosteus tropicus): Caso cooperativa de producción pesquera acuícola "El pejelagarto", S.C. de R.L.

Se evalúo la rentabilidad de la producción de pejelagarto (Atractosteus tropicus) en dos modalidades de cultivo, en condiciones de cautiverio y en cautiverio en asociación con la mojarra castarrica y tilapia en la Sociedad Cooperativa de Producción Acuícola "El Pejelagarto", localizada en Sabancuy, municipio de Carmen, Campeche, México. Para tal efecto, se utilizaron los registros de 10 años para el cálculo de los indicadores de evaluación económica siguientes para el primer modo de cultivo: valor actual neto (VAN), relación beneficio-costo (B/C), relación beneficio-inversión neta (K/N) y la tasa interna de retorno (TIR). Los resultados obtenidos, para este período, fueron: VAN = 119,825.00, B/C = 1.08, N/K = 1.88 y TIR = 25.6%. Los indicadores para el cultivo en asociación fueron VAN = 629,254, B/C = 1.43, N/K = 10.15 y TIR = 145.0%. Con base en los resultados de los indicadores, se concluye que el proyecto productivo es viable en sus dos modalidades de cultivo, desde el punto de vista económico; por lo anterior, la cría, producción y comercialización de pejelagarto, tiene una gran oportunidad de negocio, por ser una especie con demanda, dentro y fuera de la región, por su rusticidad en la cría además de ser considerado un platillo exótico