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SSRN 2023年

作者： Valenga, Matheus Villian de Lima, Rubia Catarina Przybysz Pereira, Elias Pereira, Eduardo Farias, Marcelo Miranda Pianaro, Sidnei Antonio State University of Ponta Grossa Postgraduate Program in Engineering and Materials Science Carlos Cavalcanti Avenue 4748 Uvaranas Paraná Ponta GrossaCEP: 84030-900 Brazil

HIGHLIGHTS Metakaolin-based geopolymeric mortars are not negatively affected by *** aggregates contribute to geopolymer matrix consolidation and *** cement partial replacement by metakaolin reduces AAR effects in *** ... 详细信息

关键词： Mortar

Facile Synthesis, Structure and Battery-Type Behavior of Graphene Oxides

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SSRN 2023年

作者： Silva, Jullyani M.D. Fenandes, Filipe P.M. Silva, Mariana de O. Maraschin, Thuany G. Ferreira, Luciena S. Macedo, Daniel A. da Silva, Lucineide B. Fim, Fabiana de C. Materials Science and Engineering Postgraduate Program UFPB João Pessoa58051-900 Brazil Department of Materials Engineering UFPB Paraíba João Pessoa58051-900 Brazil RS Porto Alegre90619-900 Brazil

Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. In this work, we report a simple, safe and fast synthesis method for obtaining graphene oxide as a functional material for battery-type electrodes. The method provides to obtain an aqueous solution of graphene oxide suitable for drying by freeze-drying (sample GO1). Washing and freeze-drying processes are performed to assess their effects on the exfoliation and removal of functional groups from the graphene sheets (sample GO2). GO1 sample consists of a stack of 10 oxidized graphene layers without any additional exfoliation process, while the GO2 sample has 8 stacked layers, after two washing and freeze-drying processes. FTIR results indicate that bulkier groups such as carboxylic acid are most likely to be found on the edges and surfaces of the graphene sheets of both samples. The presence of point defects such as vacancies was also observed in both samples, with the GO2 sample having a higher content of vacancies. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicate an improved specific capacity of 10.15 C g-1 for GO1 against 4.55 C g-1 for GO2 at a specific current of 0.5 A g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, is most likely due to a higher degree of oxygenated groups on its surface, as shown by EDS and FTIR studies. © 2023, The Authors. All rights reserved.

关键词： Washing

Utilization of Pineapple Crown Fiber and Recycled Polypropylene for Production of Sustainable Composites

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Journal of Renewable materials 2020年第10期8卷 1327-1341页

作者： Alexandra Augusta Reichert Mariana Ribas de Sá Gabriela Escobar Hochmuller da Silva Cesar Augusto Gonçalves Beatrice AndréRicardo Fajardo Amanda Dantas de Oliveira Postgraduate Program in Materials Science and Engineering(PPGCEM) Federal University of Pelotas(UFPel)Pelotas96075-630Brazil Technology Development Center(CDTec) Materials EngineeringFederal University of Pelotas(UFPel)Pelotas96075-630Brazil Postgraduate Program in Materials Science and Engineering(PPGCEM) Federal University of São Carlos(UFSCar)São Carlos13565-905Brazil Laboratory of Technology and Development of Composites and Polymeric Materials Federal University of Pelotas(UFPel)Pelotas96010-900Brazil

Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the *** the large number of available biofibers in nature,their use in the development of polymeric composites has inevitably emerged,it is also necessary to take into account the countless discarded plastics that still have the potential to be *** this work,fibers were extracted from pineapple crown residues and utilized to compose sustainable composites using recycled polypropylene from cups discarded in the trash as a ***,it is known that for good performance,it is necessary to achieve a good chemical interaction between the fiber and the *** order to improve this interaction,alkaline mercerization treatment was carried out on the surface of the fibers removing some components incompatible with the *** this work,the effect of the mercerization treatment on the properties of the fibers was studied,as well as their interaction with the *** effect of fiber concentration on the mechanical and thermal properties of composites was also *** of 5 and 7 wt%were used for both natural and mercerized fibers.A decrease in the number of degradation stages was observed through thermogravimetry analyses(from four in natural fiber to two in mercerized fibers),showing that the mercerization performed on the fibers was *** increase in the degree of crystallinity of mercerized fibers was also observed through the results of X-ray *** techniques indicate that amorphous compounds,such as hemicellulose and lignin,were partially *** the tensile test,it could be noted that all composites presented higher values of de elastic modulus than recycled polypropylene without added load;however,there were no differences in the elastic modulus between the different types of fibers and load ***,it is interesting to use fibers as r

关键词： Recycling composites polypropylene biofibers pineapple crown

Novel spent bleaching earth industrial waste as low-cost ceramic membranes material: elaboration and characterization

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materials Today: Proceedings 2023年 87卷 136-140页

作者： Rahma A. Elma M. Roil Bilad M. Isnasyauqiah Rahman Wahid A. Sirajul Huda M. Resa Lamandau D. Doctoral Program of Environemntal Science Postgraduate Program Lambung Mangkurat University Jl Brigjen H. Hasan Basri Kayutangi South Kalimantan Banjarmasin 70123 Indonesia Materials and Membranes Research Group (M2ReG) Lambung Mangkurat University Jl A. Yani Km 36 South Kalimantan Banajrbaru 70714 Indonesia Chemical Engineering Department Engineering Faculty Lambung Mangkurat University Jl A. Yani Km 36 South Kalimantan Banajrbaru 70714 Indonesia Faculty of Integrated Technologies Universiti Brunei Darussalam Gedung BE1410 Brunei Darussalam

Ceramic membrane support derived from spent bleaching earth (SBE) become a novel study due to their low-cost, sustainable features, abundance material, and there is not yet applicated as membrane. In this study, flat disk ceramic membrane configuration was fabricated and characterized from solid waste of crude palm oil bleaching process by pressing method in different SBE loading mass (38–42 %wt.). The SBE as raw material was deoiled using n-hexane and acetone solvent, followed by fabricated it become flat disk SBE membranes. Afterward, the SBE flat disk membranes was characterized through fourier-transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF) analyzer. The result exhibits the flat disk SBE ceramic membrane has dimension of 41 and 6 mm for diameter and thickness, respectively. SBE membranes indicating have montmorillonite structure due to presence of silica as main component materials of SBE. Besides that, the existence of siloxane vibration band in SBE membranes for the sample after regeneration with n-hexane and acetone were dominated over using raw SBE. It concludes the oil residue was removed and produced SBE membrane properties become robust with less organic contaminant. © 2023

关键词： Ceramic membrane CPO Pressing method SBE Support

Influence of Treatment Time on the Synthesis of Copper Oxide Films by Cathode Cage Plasma Deposition

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SSRN 2023年

作者： de Carvalho, Júlio F.S. Monção, Renan M. de Sousa, Ediones M. da Luz Lima, Cleânio Costa, Carla L.S.C. Garcia, Ramón R.P. Feitor, Michelle C. de Carvalho Costa, Thércio H. Libório, Maxwell S. de Sousa, Rômulo R.M. Federal University of Piauí Graduate Program in Materials Science and Engineering PI Teresina Brazil Federal University of Piauí Physics Postgraduate Program PI Teresina Brazil Federal university of Rio Grande do Norte Department of Materials Science and Engineering RN Natal Brazil Federal University of Rio Grande do Norte Department of Mechanical Engineering RN Natal Brazil Federal university of Rio Grande do Norte School of Science and Technology RN Natal Brazil

Copper oxide is a valuable p-type semiconductor for photovoltaic applications. In this work, plasma deposition with cathodic cage (CCPD) of copper oxide (CuO+Cu2O) films on glass was performed to evaluate the microstructural, morphological, chemical, and bandgap changes as a function of the treatment time variation (2, 3, 4, and 5 hours). The samples were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive System (EDS), X-ray Diffraction (XRD), and Raman Spectroscopy to identify morphologies, chemical composition, and crystalline phases of the deposited films, and the absorption spectrum optics was used to calculate the bandgap width. All films showed bandgap energies around 2.60 eV. However, the sample treated with a time of 3h presented a compact coating with 1.46 µm of thickness and bandgap energy equal to 2.57 eV, being the best result. © 2023, The Authors. All rights reserved.

关键词： Energy gap

Tecnological Tests of the Pegamites Residues Extraction at Alto Dois Irmãos/Pb in Borborema Pegmatitic Province/Bpp

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SSRN 2023年

作者： Silva, Gerson Ferreira de Brum, Irineu Cordeiro, Vinícius Becheleni, Emily Araújo, Defsson Federal University of Rio Grande do Sul – UFRGS Postgraduate Program in Mining Engineering Metallurgical and of Materials Brazil Federal University of Rio Grande do Sul – UFRGS Department of Metallurgical Engineering Postgraduate Program in Mining Engineering Metallurgical and Materials Brazil Federal University of Campina Grande – UFCG Academic Unity of Mining and Geology Brazil Federal University of Vales do Jequitinhonha e Mucuri – UFVJM Engineering Institute Science and Technology Brazil Federal University of Campina Grande – IFPB Federal Institute of Science Education and Technology of Paraíba Campus Picuí Brazil

The Borborema Pegmatitic Province – BPP situated between Paraiba and Rio Grande do Norte states in Brazilian northeast presents several pegmatites occurrences. In the region of the county of Pedra Lavrada – PB, are observed various mineral occurrences where the pegmatites have been explored with prominence at Alto Dois Irmãos-PB pegmatite, in what quartz, feldspar and mica are extracted. Because an existence of a complex mineralogy of the pegmatites, the understanding about mineral constituent is fundamental to define its industrial employment and also to implement improvements in beneficiation process. The proposal of this research line is the detailed characterization and proof that part of the ore (quartz) considered sterile, presents low poisoning (Fe2O3) and high silica (SiO2) content, to enable its industrial use mainly to nobler purposes. Also will be fundamental to minimize the environmental impact and decrease the grinding energetic consume. Besides that, the obtained results of this research will be used in a future work, as inputs in simulation stage, aiming to optimize the researched beneficiation unity grinding process. To the pegmatite characterization were done density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then were done tests to Work Index (WI) calculous. The sterile (quartz extraction) from pegmatite mining in Pedra Lavrada/PB presented medium density of 2,66g/cm3, majority chemical composition of silicon and oxygen and quartz as the mainly mineralogical stage, through X-ray diffractograms and scanning electron microscopy images, what indicates that this material has high purity. The Work Index (WI) was 15,9 kwh/t, showing that this material presents in the pegmatite can be consider resistant to breaking in grinding process. © 2023, The Authors. All rights reserved.

关键词： Quartz

High fluorescent carbon dots/Ag as a sensitive sensor for tetracycline waste in aqueous solution 10

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High fluorescent carbon dots/Ag as a sensitive sensor for te...

10th International Seminar on New Paradigm and Innovation of Natural sciences and itsApplication, ISNPINSA 2020

作者： Alkian, I. Sutanto, H. Hadiyanto, H. Hidayanto, E. Hapsari, H.P. Wibowo, A.A. Syahida, A.N. Irianti, F.D.D. Master Program of Environmental Science School of Postgraduate Studies Diponegoro University Semarang Indonesia Departemen of Physics Faculty of Science and Mathematics Diponegoro University Semarang Indonesia Departemen of Chemical Engineering Faculty of Engineering Diponegoro University Semarang Indonesia Smart Materials Research Center Laboratory Diponegoro University Semarang Indonesia

Currently, antibiotics waste produced by hospitals and pharmacies is increasing, increasing demand and public consumption. Tetracyclines are a popular type of antibiotic that can pollute the environment even in low concentrations. This study aimed to detect tetracyclines in an aqueous environment using C-dots/Ag. C-dots material was synthesized by microwave radiation method with the addition of Ag 0-4 %. C-dots/Ag is produced in the form of a brown-black powder that glows green. FTIR testing shows that C-dots/Ag contains various functional groups O-H, N-H, C-H, C=O, and C=C. The surface morphology of the C-dots based on SEM testing is round and rough. Ag's addition causes C-dots' surface morphology to agglomerate, shifting the C-dots' absorbance peaks towards a larger wavelength and decreasing the energy bandgap. C-dots/Ag 2% has the best optical properties based on the intensity of the resulting fluency. In general, C-dots/Ag has excellent potential to be a susceptible, selective, and effective tetracycline detection agent. © Published under licence by IOP Publishing Ltd.

关键词： Surface morphology

Waste Valorization from Brazilian Nepheline Syenite Processing as a Strategic Approach to Advancing the Circular Economy

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SSRN 2023年

作者： Santos, Diego Haltiery Rosa, Laura Pereira Alves, Cleidson Rosa Simão, Lisandro Arcaro, Sabrina Klegues Montedo, Oscar Rubem Raupp-Pereira, Fabiano Graduate Program in Materials Science and Engineering University of the Extreme South of Santa Catarina Criciúma88806-000 Brazil Department of Civil Engineering Federal Institute of Santa Catarina Criciúma88813-600 Brazil Research Group on Sustainability and Waste Management Postgraduate Program in Environmental Technology University of Ribeirão Preto Ribeirão Preto14096-900 Brazil Brazil

The growing disparity between the high extraction of natural resources and low use of waste as alternative mineral resources will aggravate the scarcity of natural reserves. Therefore, the current linear economy model must be converted to sustainable economic models, such as the circular economy. To achieve this transition, it is important that waste recovery strategies are implemented with a continuous search for solutions for these materials. Thus, this study investigates the waste from the processing of nepheline syenite stone, to promote its valorization as an alternative mineral resource. The classification, potentiality, quantity/viability and applicability (CPQvA) criteria are used as tools to aid decision-making for the waste valorization. The environmental, physical, chemical, morphological, and durability characteristics of nepheline syenite waste (NSW) are analyzed. The results showed evidence for the substitution of NSW for up to 100% of fine aggregates and 25% of Portland cement in civil construction. Furthermore, NSW yields recoveries of more than 90% of potassium for use in agriculture, and up to 70% of iron ore for use in steelworks. Therefore, the results indicate that NSW is viable for different applications, contributing to industrial symbiosis and a strategy for advancing the circular economy. © 2023, The Authors. All rights reserved.

关键词： Sustainable development

Performance of atrial conduction velocity algorithms with error-prone clinical measurements for the identification of atrial fibrosis

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Computers in Biology and Medicine 2025年 191卷 110119-110119页

作者： Gharaviri, Ali Vigneswaran, Vinush Vickneson, Keeran Roney, Caroline Corrado, Cesare Coveney, Sam Maciunas, Kestutis Bodagh, Neil Klis, Magda Kotadia, Irum Sim, Iain Whitaker, John Bishop, Martin Niederer, Steven O'Neill, Mark Williams, Steven E. Centre for Cardiovascular Science The University of Edinburgh United Kingdom School of Biomedical Engineering and Imaging Sciences King's College London United Kingdom School of Engineering and Materials Science Queen Mary University of London United Kingdom National Heart & Lung Institute - Faculty of Medicine Imperial College London United Kingdom Heart Rhythm Research Brussels Postgraduate Program in Cardiac Electrophysiology and Pacing Vrije Universiteit Brussel Brussels Belgium Heart Rhythm Management Centre Universitair Ziekenhuis Brussel Brussels Belgium Brussels1050 Belgium

Introduction: Measuring conduction velocity, as a direct consequence of fibrosis, may provide a better method to localise fibrotic regions. This study aims to assess established cardiac conduction velocity calculation methods (Triangulation, Polynomial Surface Fitting, and Radial Basis Function) in identifying areas of conduction slowing caused by fibrosis, considering realistic measurement errors. Method: Using a human left atrium computational model, atrial activation was simulated. Each conduction velocity calculation method's performance was evaluated under uncertainties in mapping point density, local activation time assignment and electrode locations by comparing calculated conduction velocity to ground truth conduction velocity derived from high-resolution simulated atrial activation. Results: All methods agreed well with ground truth conduction velocity maps in noise-free, high-density sampling conditions. However, Triangulation and Polynomial Surface Fitting methods showed susceptibility to noise, exhibiting significant errors under moderate to high noise levels. Radial Basis Function method demonstrated greater robustness to noise and reduced sampling density. Fibrotic region identification accuracy was high under ideal conditions for all methods but declined with increasing noise, with the Radial Basis Function method maintaining superior performance. Conclusion: While all methods accurately estimate conduction velocity under ideal conditions, the Radial Basis Function method shows robustness to a realistic clinical noise, hence making it the most suitable to identify fibrotic regions. © 2025

关键词： Triangulation

Study of doxorubicin release carried out by pH-responsive chitosan-alginate hydrogels

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Journal of Molecular Liquids 2025年 429卷

作者： Oliveira, Thayane Portela da Silva, Jhaemely Gabrielly Vieira Costa, Paloma Maia de Oliveira, Maykol Christian Damasceno Coelho, Ronaldo Cunha Santos Nascimento, Ariane Maria Silva Silva-Filho, Edson Cavalcanti dos Santos, Francisco Eroni Paz Muniz, Edvani Curti Postgraduate Program in Engineering and Materials Science Federal University of Piauí PI Teresina64049550 Brazil Physics Department Federal University of Piauí PI Teresina64049550 Brazil Department of Teacher Training Instituto Federal do Piauí PI Teresina64053-390 Brazil Chemistry Department Federal University of Piauí PI Teresina64049550 Brazil Chemistry Department State University of Maringá PR Maringá87020-900 Brazil

The use of polysaccharides in drug delivery systems has attracted increasing interest due to their functional properties. Among these, alginate (ALG) and chitosan (CH) are promising candidates for sustained drug delivery as they respond to pH, ensuring that the compound is released in a desired area. In this research physical hydrogels based on alginate and chitosan (ALG/CH) were prepared by varying the synthesis parameters (ALG at ALG/CH ratio, pH and speed stirring) and the effects of such parameters on hydrogels’ chemical and physical structure were accessed through several techniques. Also, the effects synthesis parameters on fractional release (Fmax), half time (t1/2) and percentage encapsulation efficiency (EE%), as the evaluated responses, were statically measured using a factorial design. Analysis through Raman and FTIR spectroscopies revealed the modes and bands corresponding to the precursors, confirming the formation of physically cross-linked hydrogels. The porous structure of the materials was confirmed by scanning electron microscopy (SEM). The swelling capacities of the hydrogels were analyzed at different pHs (5.4 and 7.4) and demonstrated that absorption increases in slightly acidic media. TG/DTG and Micro-CT analyzes of the sample with the greatest swelling showed that the degradation of the hydrogel occurs in two endothermic events and that the material possesses several sized and interconnected pores. The doxorubicin (DOX) release study showed that the release rate is higher as the higher proportion of CH relative to ALG. The factorial design analysis indicated the statistically significant factors in the DOX release tests. Thus, the results suggest that ALG/CH hydrogels can be tuned during their preparation to achieve optimal structure for pH-responsive to be applied for DOX releasing system. © 2025 Elsevier B.V.

关键词： Microgels