Selection Of Adequate Materials Research Articles

( General Student Poster Award Winner, 1st Place) Organic Electrochemical Transistors for High-Performance Electrocorticography Recording

Instrumentation used in biopotential recordings is paramount in ensuring correct representation of electrophysiological activity, affecting medical diagnosis and intervention. Additionally, high signal fidelity challenges the engineering of future neural interfaces, requiring high Signal to Noise Ratios (SNR), high spatial and temporal resolution, and low-cost. Recently, transistor-based technologies have garnered increased attention and are being used as bio-electronic interfaces due to their inherent amplification capabilities. Specifically, Organic Electrochemical Transistors (OECTs) stand at the forefront of this technological shift given their low voltage operation, miniature size, biocompatibility, and high transconductance (gm), a measure of amplification. Within an electrolyte environment, OECT channel conductivity is modulated by the charge carrier concentration, changing with the voltage level inside the medium, which, if tied to a biopotential, can be concluded by measuring the drain current.In this work, we designed and developed an OECT-based neural interface employing an in-plane gate, pioneering its use in-vivo to guarantee operation at peak gm. For device fabrication, we employed inkjet printing, thus avoiding cumbersome multi-step cleanroom microfabrication, reducing costs and facilitating production.OECTs were fabricated following a three-step fabrication process. First, gold nanoparticle ink was used to pattern the source, drain, and gate on a polyimide backbone. Next, polyimide ink was deposited over the connecting leads for insulation, and finally, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was layered to form the semiconducting channel. The devices’ electrical characteristics were assessed in a phosphate buffer solution (PBS) with either the gold in-plane electrode or an Ag/AgCl probe as the gate. To achieve efficient in-plane gating, the gold electrode was modified with PEDOT:PSS layering to decrease the voltage drop across the gate/electrolyte interface and minimize spatial footprint. To showcase the use and effectiveness of including an in-plane gate, artificial hippocampal neuronal spikes were fed to the OECT at different gate biases. The in-vivo performance of the OECT was evaluated by implanting it onto the cortex of a rat model and assessing its efficacy in recording electrocorticographic (ECoG) activity. Furthermore, low impedance PEDOT:PSS-coated gold passive electrodes were fabricated adjacent to the transistor’s channel for performance comparison. Seizures were induced via intra-amygdala injection of kainic acid (KA), and recordings were acquired from the sensory-motor cortex.Inkjet-printed OECTs realized in this work had a channel length of 15µm, a width of 130µm and a channel thickness of 250nm. To efficiently gate the device, the voltage drop across the gate/electrolyte interface must be negligible compared to the one experienced at the channel. This can be achieved by increasing the channel-relative gate capacitance, and we show that PEDOT:PSS coating of the electrode efficiently minimizes the drop compared to increasing its size, which is favorable in a spatially limited application like ECoG recordings. In addition, the developed OECTs achieved a high gm of 14mS, a quick response time of 0.5ms, and a compact channel area of 1950µm2, setting our OECT apart from existing high performing devices in literature. In addition, we highlight the importance of adequate material selection for source and drain metals and channel thickness in controlling the operational bandwidth of the device, given that high frequency oscillations, which are typically seen in seizure activity, present a challenge to OECTs that experiencing intrinsic gm drops at high frequencies. Upon comparison of gold and silver nanoparticle inks, results show that the usage of gold increases cut-off frequency for both thick and thin channels. Furthermore, we demonstrate that applying a cathodic potential through an in-plane gate placed in proximity to the channel ensures operation at peak transconductance where amplification is at its highest. At optimal operation, OECT peak amplitudes increased by up to 133% compared to the absence of the gate, accompanied by an increase in SNR. In vivo, OECTs outperform low-impedance passive electrodes and successfully record distinct seizure features, mainly sharp spike-wave discharges, and bursts, achieving a high SNR of 48dB.Next generation neural interfaces must provide high fidelity and localized recordings. Electrochemical solutions arise as a promising candidate to replace conventional passive electrodes, offering high resolution and SNR. In this work, we designed and built low-cost OECTs using inkjet printing, coupled with an in-plane gate to maximize performance. The developed sensor is employed in vivo and shown to outperform low-impedance passive electrodes by recording distinct seizure phases. This technology shows great promise to develop into a general-purpose active recording component in the diagnosis and monitoring of neurological disorders or other applications in biopotential sensing.

Electrospun High Performance Polymer Reinforced Membranes for Exceptional Durability Fuel Cell Membrane Electrode Assemblies

Adequate material selection is one of the most important aspects in component design. Therefore, high-performance polymers have garnered significant interest for Proton Exchange Membrane Fuel Cell (PEMFC) and Water Electrolysis (WE) applications due to their exceptional mechanical, thermal, and chemical properties. This 'beginning by design' strategy requires a deep knowledge of environmental stressors and degradation mechanisms and focuses on proposing next-generation advanced materials able to withstand defined stress conditions for lightweight and heavy-duty transport applications. This presentation presents recent advances and challenges encountered in the preparation of high-performance polymer-reinforced membranes and highlights their specific properties resulting in exceptional durability of nearly 120,000 cycles when tested under combined Open Circuit Voltage (OCV) with Relative Humidity (RH) cycling.This work was supported by the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 101006641 IMMORTAL. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme, Hydrogen Europe and Hydrogen Europe Research.

Structural performance of prefabricated glass fibre concrete floor panel versus compressed fibre cement floor panel for an optimised volumetric module- A case study

Efficient design with an adequate selection of materials plays a significant role in the serviceability and durability of the volumetric modules in modular construction. Literature and experience indicate that the design life of the volumetric module is heavily dependent on its floor's serviceability. Improper design along with an inadequate selection of material for the floor of the volumetric module can lead to damages to the other structural and non-structural elements such as walls and services etc. This paper aims to present the sustainable, optimised and serviceable structural design for the floor of a volumetric module. A common volumetric module of the modular industry, i.e., a prefabricated bathroom pod is taken as an example to demonstrate the efficacy of sustainable Glass Fibre Concrete (GRC) over the existing Compressed Fibre Cement (CFC) system. The structural analyses and design were carried out using finite element modelling and optimization through Design for manufacture and assembly (DfMA) computations in the current research. The entire modules with GRC and CFC floor panels were subjected to various loading conditions in the numerical models to compare their serviceability. The outcomes of the models revealed the better performance of GRC material over the CFC for the floor of the prefabricated bathroom pod. Moreover, through Design for Assembly (DfA) computations the efficiency in the manufacturing of the module with GRC was proposed. Furthermore, statistical models for the prediction of deflections of the floors and their correlation were developed.

Assessment of Water Sorption, Solubility and Interface Properties for Two Different Pit and Fissure Sealants

The purpose of modern dental medicine is to prevent dental caries and promote minimally invasive techniques at the expense of invasive methods. Dental sealants are largely recommended for occlusal surfaces protection, but concerns are related about microleakage at material-enamel interface. This in vitro study aimed to investigate the association between chemical structure, sealing capacity and marginal infiltration for 2 fluoride F containing commercially available resin-based sealants: Pit&Fissure� Sealant (DMP) and Fissurit FX� (Voco) in order to achieve a better description and ensure adequate material selection in every day practice. An optimal resin-based sealant should mimic the structural, physical and mechanical characteristics of enamel. The main difference between the sealing materials tested is based on the amounts of inorganic filler and on the various shapes of the particles in the filler. Pit&Fisure� Sealant express less attachment at enamel interface, higher sorption and greater water solubility, when compared to Fissurit FX�. The better sealing capacity of Fissurit FX� can be described by the homogeneity of the material and the very small size of the inorganic fillers. Dental materials properties used as pit and fissure sealants are sensitive to mechanical, thermic and chemical stress from oral cavity. Regular dental check-up can detect the presence and integrity of sealant and ensure preventive effect in time.

Fracture toughness, fatigue crack resistance and wear resistance of two railroad steels

This research evaluated the microstructure and compared important mechanical properties of two steels for use in the railway sector. The main objective of the work was to verify the possibility of replacing a traditional C-Mn-Si pearlitic steel widely used in the world for application on rails, here called CS (common steel), by an also pearlitic steel with Nb and V micro-additions, rarely applied on rails, here called MS (microalloyed steel). The microstructures were characterized by means of pearlite colony size and pearlitic interlamellar spacing measurements, using light optical microscopy (LOM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical properties were evaluated by tensile tests, hardness tests, fracture toughness tests, force controlled axial fatigue tests, fatigue crack growth rate tests and microabrasion wear tests. CS presented a more refined microstructure than MS, due to differences in the thermomechanical industrial procedures. However, hardness, yield and tensile strength, and fracture toughness were similar for both steels. The main differences in the mechanical behavior were verified in the tensile ductility, fatigue crack growth resistance and wear resistance; the value for these three properties was higher for MS. Considering the main metallurgical requirements for an adequate selection of materials to be applied in the railway sector, these results show that the use of a Nb-V microalloyed steel is therefore a good option to ensure the best performance in service of the rail.

Corrosion control of nuclear steam generators under normal operation and plant-outage conditions: a review

Abstract Nuclear steam generators (NSGs) are key components of nuclear power plants (NPPs) since their reliability affects the overall plant performance. Corrosion control of steam generators under operation and during plant outages is attained by proper design, adequate material selection and control of water chemistry in the entire secondary cooling circuit. This article reviews the types of steam generators, the materials used for their construction (with a special focus on tubing alloys), the corrosion processes that may occur under operation and the strategies to preserve steam generators and other components of the secondary cooling system from corrosion during plant outages.

Using integer Linear Programming to minimize the embodied CO2 emissions of the opaque part of a façade

Buildings are responsible for about 36% of the CO2 emissions in Europe but there is a significant potential to reduce these emissions. This paper deals with the embodied CO2 emissions of the opaque part of a façade, which include the life cycle of any material used in its construction: excavation, processing, construction, operation, maintenance, demolition and waste or recycling.With the aim of minimizing such embodied CO2 emissions, an Integer Linear Programming problem is presented, in which CO2 emissions are minimized depending on other parameters involved in the construction of the façade, like the maximal thermal transmittance allowed by current legislation, thickness of the wall, budget, availability of materials for the different layers of the wall, etc.The paper also shows a case study based on a constructive solution for the opaque part of the envelope defined by up to six layers, with more than 1.1 million possible combinations. This case study considers seventy scenarios depending on maximal allowed thermal transmittances and thickness intervals for five different technologies applied to the structural element of the wall. Results show that an adequate selection of materials can reduce the embodied CO2 emissions of the opaque part of the envelope up to 78.5% for similar values of transmittance and thickness.

A CMOS-Integrated MEMS Platform for Frequency Stable Resonators-Part I: Fabrication, Implementation, and Characterization

This paper introduces the comprehensive design concepts, procedure, and post-process flow of a robust manufacturing platform for complementary metal-oxide- semiconductor microelectromechanical systems (CMOS-MEMS) resonant transducers with enhanced frequency stability and capacitive-transduction efficiency. Thanks to a sandwich-stacking configuration of the interconnection metal line (TiN/AlCu/TiN) existing in standard CMOS technology, a deep-submicron TiN-to- TiN gap is successfully demonstrated by removing the central AlCu alloy layer through the proposed post-fabrication platform, thus realizing a novel titanium nitride composite (TiN-C) structure. Compared with the traditional release approaches utilized in the general post-CMOS fabrication, the proposed TiN composite transducer with TiN-to-TiN gap can simultaneously attain (i) a 400nm air gap for effective electrostatic transduction, (ii) adequate material selection and arrangement for near-zero frequencytemperature coefficient, and (iii) conductive electrodes to overcome frequency drift induced by dielectric charging during capacitive operation. In Part I of this study, the design guideline, layout rules, and detailed post-fabrication flow are addressed. The fabrication results of each post-process step are also exhibited. Numerical analysis, experiment results, and further discussions in terms of frequency stability for resonant transducers will be covered in Part II. [2018-0230]

Desenvolvimento de metodologia para avaliação da adesividade agregado-ligante com o uso de processamento digital de imagem

A adesividade na interface agregado-ligante de misturas asfálticas é uma propriedade importante de se avaliar de modo a prevenir danos relacionados a umidade em pavimentos asfálticos. No Brasil, um dos ensaios normatizados para analisar essa propriedade é denominado Agregado graúdo: Determinação da adesividade ao ligante betuminoso (NBR 12583-2017), que proporciona um resultado qualitativo (satisfatório ou insatisfatório). A presente pesquisa visa desenvolver uma metodologia usando processamento digital de imagens a partir de imagens obtidas de smartphone que possibilite a determinação do percentual de área de agregado recoberto pelo ligante asfáltico, tornando o resultado do ensaio quantitativo. Foram analisadas 37 imagens para a calibração, além da análise de 5 imagens padrão, cujas dimensões são conhecidas, para comparação com as áreas obtidas por meio da presente metodologia. Os resultados indicaram ser possível quantificar o percentual de área do agregado recoberto pelo ligante, além da identificação dos agregados outliers. A metodologia mostrou-se promissora e executável em curto prazo, tendo em vista a rapidez de execução e a precisão dos resultados, podendo auxiliar na caracterização e seleção adequada de materiais para uso em pavimentação asfáltica.

Maximization of performance of a PCM – based thermal energy storage systems

Phase change materials (PCMs) are significant in terms of applicability for the thermal energy storage (TES). Thanks to the high thermal storage density and wide range of phase transition temperature they are promising storage mediums for a large number of applications. PCMs can be used to support efficient use of waste or excess heat. Selection of adequate material as well as design of optimal TES magazine are crucial. It is important to choose material which is characterized by suitable temperature range of phase transition, possibly high latent heat of transition, specific heat and thermal conductivity. Also important features are: ability to work properly after many operation cycles, minimum volume change and gas generation during the phase transition. It is also advantageous when PCM is non-toxic and non-corrosive, non-flammable, non-explosive, environment friendly and easy to recycle. Even the best designed PCMs would not be able to store heat efficiently if the whole magazine and its construction were not good enough. This is the reason why a lot of effort is taken to design effective TES system. The aim of this work is to analyse examples of different configurations of PCM – based thermal energy storage systems. Authors compare selected TES systems and discuss their characteristics.

Efficacy of chemical sanitizers against Bacillus cereus on food contact surfaces with scratch and biofilm.

This study was performed to investigate the efficacy of chemical sanitizers (viz., chlorine, chlorine dioxide, alcohol, and quaternary ammonium compound) against Bacillus cereus on five food contact materials under different conditions (smooth vs. scratched and with vs. without biofilms). After incubating materials in B. cereus suspension, cell adhesion on a smooth surface (10cm2) was in the following ascending order: stainless steel (7.36 ± 0.08 log CFU), glass (7.51 ± 0.26 log CFU), polyethylene (7.66 ± 0.30 log CFU), polypropylene (7.76 ± 0.30 log CFU), and wood (8.02 ± 0.33 log CFU). The efficacy of sanitizers was dramatically reduced in the presence of a biofilm on all materials. Among four different chemical sanitizers, chlorine showed the best bactericidal activity against B. cereus on the surface with scratch and biofilm. Selection of adequate materials, maintenance of a smooth surface, and inhibition of biofilm formation are good practices for food safety.

Physicochemical interactions among α-eleostearic acid-loaded liposomes applied to the development of drug delivery systems

In this study, α-eleostearic acid-loaded (α-ESA-loaded) dimyristoylphosphatidylcholine (DMPC) liposomes had their physicochemical properties characterized by horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy, nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). In vitro thiobarbituric acid reactive substance (TBARS) assays were performed to obtain preliminary information on the oxidative potential of the system. An α-ESA-promoted ordering effect in the lipid phosphate region was observed. It was associated with a rotation restriction due to an increase in the amount of lipid group hydrogen bonds. The fatty acid was responsible for the reduction in the degree of hydration of carbonyl groups located in the interfacial region of lipids. α-ESA disordered the DMPC methylene acyl chains by trans-gauche isomerization and increased its rotation rate. TBARS results showed pro-oxidant behavior on liposomes, induced by α-ESA. The discussion about the responses considered the degree of saturation of phosphatidylcholines and suggested that the α-ESA oxidative effects may be modulated by the liposome lipid composition. The versatility of liposomal carriers may be promising for the development of efficacious α-ESA-based drug delivery systems. Results described in this study contribute to the selection of adequate material to produce them.

Tecnologías para la enseñanza de lenguas extranjeras: una contribución para lograr los retos educativos de Brasil

Technology applied to education is an indissoluble duality needed to create flexible systems that answer society’s educational needs. Current educational systems try to encourage policies in this regard. Brazil has followed these policies and has recently created laws on them (PNE 2014-2024). This plan aims to instigate the development and diffusion of technologies since primary school and to promote innovative pedagogical practices based on the use of free software and educational resources. One of the most interesting applications for educational technology in Brazil is the field of second language learning, due to the geographical and linguistic configuration of the country. Brazil is a multilingual country, comprising a number of indigenous languages, that borders other languages of diffusion (Spanish, English and French). In this context, introducing linguistic technologies to achieve true multilingual skills at a national level is essential, as many speakers will only be able to have direct contact with the foreign languages through technology. However, the large amount of linguistic material available on the Internet hinders the selection of adequate materials for the diverse linguistic situations faced by students. This study aims to help facilitate the selection of Internet linguistic resources by offering classifications of materials and presenting a non-exhaustive but relevant portfolio of available resources created or used for learning and teaching second languages. This study is organized into the following sections: after the introductory overview, the first section analyses the current education goals in Brazil, as reflected in the PNE 2014-2024, focusing specifically on aspects related to the use of technology. The second section examines the availability of educational technologies geared towards language teaching, starting with a distinction between institutional technologies and non-institutional technologies. The next section proposes a classification of non-institutional technologies intended for the optimization of the resources available on the Internet for foreign language teaching. The suggested classification can be very helpful for teachers, who have to deal daily with the task of selecting the most suitable language-teaching resources off the Internet. Keywords: ICT, linguistic policy, foreign languages, Internet, Brazil, teaching.

On the influence of Seebeck coefficients on adhesive tool wear during sheet metal processing

During every kind of sheet metal manufacturing process, thermoelectric voltages and currents result from a temperature rise between tool and sheet metal. Their influence on the process and tool wear behavior has been investigated insufficiently so far. Therefore, Seebeck coefficients, representing thermoelectric properties, have been determined for several materials. The correlation between different Seebeck coefficients of tool, respectively, sheet materials and arising thermoelectric currents are exemplarily shown by an instantaneous measurement during blanking. An adequate material selection with regard to thermoelectric properties reduced adhesive wear to 22%. The obtained results improve the fundamental understanding of wear causing interactions.

Acoustic imaging and mirage effects with high transmittance in a periodically perforated metal slab

In this paper, we present a high-quality superlens to focus acoustic waves using a periodically perforated metallic structure which is made of zinc and immersed in water. By changing a geometrical parameter gradually, a kind of gradient-index phononic crystal lens is designed to attain the mirage effects. The acoustic waves can propagate along an arc-shaped trajectory which is precisely controlled by the angle and frequency of the incident waves. The negative refraction imaging effect depends delicately on the transmittance of the solid structure. The acoustic impedance matching between the solid and the liquid proposed in this article, which is determined by the effective density and group velocity of the unit-cell, is significant for overcoming the inefficiency problem of acoustic devices. This study focuses on how to obtain the high transmittance imaging and mirage effects based on the adequate material selection and geometrical design.

Development of Technology for Creating Composite Materials of Machine Tool

A technology for creating new composite materials with hybrid properties desired by many designers was developed and evaluated. Young’s modulus, density, coefficient of linear expansion, specific heat and thermal conductivity were calculated through a newly developed software. This software has two functions which are (1) the selection of adequate materials and the calculation of their ratios to achieve specific desired properties in a new composite material (2) the calculation of resultant properties given that the component materials and their rations in a composite material are known. The new composite material for the tool post of a machine tool was manufactured and evaluated. It is concluded from the results that the technology was very effective and useful for development of a new composite material with several hybrid properties.

Ranking procedure based on mechanical, durability and thermal behavior of mortars with incorporation of phase change materials

Nowadays, considering the high variety of construction products, adequate material selection, based on their properties and function, becomes increasingly important. In this research, a ranking procedure developed by Czarnecki and Lukowski is applied in mortars with incorporation of phase change materials (PCM). The ranking procedure transforms experimental results of properties into one numerical value. The products can be classified according to their individual properties or even an optimized combination of different properties. The main purpose of this study was the ranking of mortars with incorporation of different contents of PCM based in different binders. Aerial lime, hydraulic lime, gypsum and cement were the binders studied. For each binder, three different mortars were developed. Reference mortars, mortars with incorporation of 40% of PCM and mortars with incorporation of 40% of PCM and 1% of fibers, were tested. Results show that the incorporation of PCM in mortars changes their global performance.

Smart Materials: Overview and a Proposal for Architecture and Construction

Here we provide a brief overview on smart materials, products and systems, from smart materials and their classification up to structured systems. We present a brief revision of smart building solutions and their combination of those creating a tendency towards buildings that may be considered smart as a whole. Also, of current smart solutions that respond to the environment, and whose smartness resides in the design of the systems along with the selection of adequate materials. The buildings’ skins, for example, are configured in such a way that they respond to the environment. To conclude, we will make a proposal on applications in the shape of charts of materials, products and systems for architecture and construction

Development of Two-Component Micropowder Injection Molding (2C-MicroPIM)-Process Development

The increasing importance of two-component microinjection molding is due to the potential to integrate different functionalities in one assembly without applying additional procedures. Furthermore, it enables a mass production technique of assemblies made up of two or more components. For mechanical advantages like toughness, hardness, or sufficient tribological behavior, metal or ceramic materials have to be used; the resulting process type is known as two-component micropowder injection molding (2C-MicroPIM). As this technology permits, in principle, the realization of fixed as well as movable junctions, a variety of new applications will be available. However, the two crucial aspects of 2C-MicroPIM research are the selection of adequate materials and an optimized process development. This article describes the challenges and approaches of the process development. The feasibility of ceramic 2C-MicroPIM assemblies has been demonstrated by a shaft-to-collar connection, which is composed by a zirconia gear wheel and a shaft made of alumina.

콘크리트 구조물에 있어서 누수균열 보수를 위한 일반지침 제안 연구

누수균열은 상시 콘크리트 구조체의 거동, 물의 성분, 수압, 온도, 화학 물질 등 다양한 환경 요인의 영향이 작용함에 따라 이에 대응할 수 있는 성능을 확보한 보수재료 및 공법이 사용되어야 한다. 본 연구에서는 콘크리트 구조물은 국가적으로 유사한 공학적 특성(배합설계, 사용재료, 시공방법, 유지관리 등)을 가지고 있기 때문에, 누수균열에 대한 보수 접근도 크게 다르지 않을 것으로 보고, 향후 유지관리 전문가들의 공통적 기술 지침의 필요에 따라 자료를 개발하였다. This study outlines a successful and effective plan for repairing water-leakage cracks in concrete structures. The lack of adequate solutions for water-leakage cracks often results in unnecessarily high repair costs, and as such this remains a problem that requires constant attention. Unfortunately, despite the availability of a vast number of different materials and methods, it is often difficult to attain a perfect waterproof sealing The reason for the difficulties in the repair of water-leakage cracks can be attributed to an insufficient knowledge and understanding of the negative factors (i.e., chemical and physical (mechanical) conditions) that cause water-leakage cracks, and of the properties of the repair materials and methods. In this study, guidelines and methods for the selection of adequate materials for the repair of water-leakage cracks in concrete structures were developed for countries that do not already have general guidelines on this subject, and for local regulatory authorities elsewhere.