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Effect of Concentration and Residence Time of Joncryl■ADR4368 on Melt Processability of Poly(3-hydroxybutyrate)

Journal of Renewable materials 2024年第12期12卷 2079-2094页

作者： Jéssica da Silva Chagas JoséElson Soares Filho Natália Fernanda Inocêncio Silva Marcelo Massayoshi Ueki Eliton Souto de Medeiros Renate Maria Ramos Wellen Mauricio Pinheiro de Oliveira Gelsoneide da Silva Gois Yêda Medeiros Bastos de Almeida Amélia S.F.Santos Post-Graduation Program in Materials Engineering(PPCEM) Federal University of Paraíba(UFPB)João PessoaPB 58051-900Brazil Laboratory of Materials and Biosystems(LAMAB) Federal University of Paraíba(UFPB)João PessoaPB 58051-900Brazil Department of Materials Engineering Federal University of Sergipe(UFS)Jardim Rosa ElzeSão CristóvãoSE 49100-000Brazil Institute of Science and Technology Federal University of São Paulo(UNIFESP)São Josédos CamposSP 12231-280Brazil Department of Chemical Engineering Federal University of Pernambuco(UFPE)Cidade UniversitáriaRecifePE 50670-901Brazil

Poly(3-hydroxybutyrate)(PHB)is a biothechnological and biodegradable thermoplastic polymer from the polyhydroxyalkanoates(PHAs)family,whose chain regularity,high molecular weight,and physical and mechanical properties comparable to polypropylene(PP)are characteristics that have made PHB a prominent commercial ***,its susceptibility to thermal degradation and hydrolysis has limited many *** address the challenges associated with processing,a random copolymer of 95.86 mol%3-hydroxybutyrate and 4.14 mol%3-hydroxyvalerate(referred as PHB)was compounded without(neat PHB)and with 0.25,0.5,1,and 1.5 wt%of chain extender(Joncryl■ADR 4368),consisting of multifunctional epoxy groups,and melt mixed in an internal mixer at 170℃,50 rpm,and residence times of 5,10,and 15 *** effect of chain extender concentration and residence time on the effectiveness of Joncryl■ADR 4368 to recover the pristine PHB properties were investigated through torque rheometry,melt flow index(MFI),differential scanning calorimetry(DSC),tensile testing,and thermogravimetric *** results indicated that an increase in residence time strongly influenced the prevalence of thermomechanical degradation reactions over chain extension reactions of PHB during processing in the molten *** residence times favored chain extension,while longer times favored chain *** trend led to no enhancement of PHB mechanical properties processed for 10 and 15 min,regardless of additive content *** flow index,thermogravimetric analysis and tensile strength exhibited an asymptotic behavior with the increase in additive concentration,exhibiting a noteworthy improvement in tensile strength and temperature at the highest rate of thermal degradation(TMAX),and a decrease in melt flow index of neat PHB with only 0.25 wt%of additive mixed for 5 *** results found in this work allow additional data for processing PHB by manipulating the ratios of multifunctional chain

关键词： PHB chain extender degradation epoxy groups viscosity

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Development of educational software for stainless steel selection and evaluating usability using the System Usability Scale (SUS)

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International Journal of Mechanical engineering Education 2024年

作者： Nery, Macclarck Pessoa dos Santos Neto, Severiano José Alves, Roberty Santos Santana, João Vitor dos Santos Griza, Sandro Martins, Carlos Otávio Damas Materials Science and Engineering Pos-graduation Program – p2cem from Federal University of Sergipe São Cristovão City Brazil Mechanical Engineering Department Federal University of Sergipe São Cristovão City Brazil Department of Materials Science and Engineering Federal University of Sergipe São Cristovão City Brazil

The use of educational technologies is an important part of the learning process. The development of educational apps and software is one of the pillars of this evolution in teaching. Material selection is one of the most important subjects in professional engineering education. Regarding materials used to manufacture products, the stainless steels are the most commonly used materials after traditional steels. In the industrial environment, fatigue, corrosion-fatigue, and stress corrosion cracking are three very important considerations in the selection of materials. This study evaluates the usability of educational software developed in Java using object-oriented programming using the System Usability Scale and compares it with results obtained from other educational technologies. © The Author(s) 2024.

关键词： Software testing

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Antibiofilm and immunomodulatory resorbable nanofibrous filing for dental pulp regenerative procedures

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Bioactive materials 2022年第10期7卷 173-186页

作者： Mauricio Gonçalves da Costa Sousa Gabriela Conceiçao de Almeida Danilo Cesar Martins Mota Rosiane Andrade da Costa Simoni Campos Dias Samuel Nunes Limberger Frank Ko Li Ting Lin Evan FHaney Hashem Etayash Beverlie Baquir Michael J.Trimble Ya Shen Zheng Su Markus Haapasalo Daniel Pletzer Letícia Chaves de Souza Glaucia Schuindt Teixeira Renato M.Silva Robert E.W.Hancock Octavio Luiz Franco Taia Maria Berto Rezende Post-Graduation Program in Genomic Sciences and Biotechnology Catholic University of BrasíliaBrasíliaBrazil Dentistry Course Catholic University of BrasíliaBrasíliaBrazil Post-Graduation Program in Health Sciences University of BrasíliaBrazil LIMA Chemistry InstituteUniversity of Brasília-UNBBrasíliaBrazil Animal Biology Department Campus Darcy RibeiroUniversidade de BrasíliaBrazil Department of Materials Engineering Faculty of Applied ScienceUniversity of British ColumbiaVancouverCanada Department of Microbiology and Immunology University of British ColumbiaVancouverBCCanada Department of Oral Biological and Medical Sciences Faculty of DentistryUniversity of British ColumbiaVancouverCanada Department of Microbiology and Immunology University of OtagoDunedinNew Zealand Department of Endodontics School of DentistryUniversity of Texas Health Science Center at HoustonHoustonUSA Department of Prosthesis Faculty of DentistryRio de Janeiro State UniversityRio de JaneiroBrazil Post-Graduation Program in Biotechnology Catholic University Dom BoscoCampo GrandeMato Grosso do SulBrazil

Multifunctional scaffolds with host defense peptides designed for regenerative endodontics are desirable nanobiotechnological tools for ***,different scaffolds were tested for use during the pulp revascularization process,including poly(vinyl alcohol)-PVA hydrogels or resins,collagen hydrogels and poly(vinyl alcohol)PVA/Chitosan(PVA/CS)*** on time to degradation(21 days),nanofibers were chosen to be incorporated with ciprofloxacin and IDR-1002(each at 50 mg/g).Nanofibers containing ciprofloxacin and IDR-1002 had anti-biofilm activity against Enterococcus faecalis,Staphylococcus aureus and a multispecies oral biofilm,besides anti-inflammatory *** in vivo subcutaneous tissue response to tooth fragments filled with nanofibers demonstrated a pulp-like tissue formation,when compared to empty teeth ***,we designed a strong antimicrobial,immunomodulatory and regenerative candidate for pulp revascularization and regeneration procedures.

关键词： Regenerative endodontics Scaffolds Nanofibers Host defense peptides Ciprofloxacin IDR-1002

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Theoretical insights into the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite Pb2SO5 structure

arXiv

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arXiv 2023年

作者： Fabris, Guilherme S.L. Ferrer, Mateus M. Sambrano, Julio R. Almeida, Cláudio R.R. Paskocimas, Carlos A. La Porta, Felipe A. Graduate Program in Materials Science and Engineering Technological Development Center Universidade Federal de Pelotas RS Pelotas96010-610 Brazil Modeling and Molecular Simulation Group São Paulo State University Bauru São Paulo17033-360 Brazil Department of Materials Engineering Federal University of Rio Grande do Norte RN Natal59078-970 Brazil Postgraduate Program in Science and Engineering of Materials Federal University of Rio Grande do Norte RN Natal59078-970 Brazil Federal University of Technology - Paraná Nanotechnology and Computational Chemistry Laboratory Avenida dos Pioneiros 3131 CEP PR Londrina86036-370 Brazil State University of Londrina Post-Graduation Program in Chemistry Rodovia Celso Garcia Cid 445 km 380 CEP PR Londrina86057-970 Brazil

Lanarkite is a mineral formed by a combination of lead, sulphur, and oxygen atoms arranged in the general chemical formula Pb2SO5 (PSO) that crystallises with monoclinic symmetry (belonging to the C2/m space group, No. 12). This mineral was first discovered in Lanarkshire, Scotland and was named after its location. PSO has a unique structure comprising alternating penta-coordinated lead [PbO5] and tetra-coordinated sulphur [SO4] clusters. This lanarkite-type structure has recently attracted significant scientific interest and has been the focus of the superconducting material research community. However, its chemistry needs to be explored further. This article presents a comprehensive investigation on the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type PSO structure from a computational perspective. Thus, different functionals in the DFT (e.g., PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP37, and B3LYP) were assessed to accurately predict their fundamental properties. All the DFT calculations were performed using a triple-zeta valence plus polarisation basis set. Among all the DFT functionals tested in this study, PBE showed the best agreement with the experimental data available in the literature. Our results also reveal that the [PbO5] clusters are formed with three Pb–O bond lengths, with values of about 2.32, 2.59, and 2.84 Å, respectively, while the [SO4] clusters have the same S–O bond length of 1.57 Å. We performed a complete topological analysis of this system to comprehend these structural differences. Additionally, the PSO structure has an indirect band gap energy of 2.9 eV and an effective mass ratio (mℎ∗ /me∗) of about 0.415 (using PBE calculations) which may, in principle, indicate a low recombination of electron-hole pairs in the lanarkite structure. Therefore, we believe that a detailed understanding of their electronic structures, spectroscopic properties as well as their chemical bonding is critically important

关键词： Lead compounds

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Sensitization of TiO2 nanoparticles with natural dyes extracts for photocatalytic activity under visible light

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Dyes and Pigments 2020年 182卷 108654-108654页

作者： Goulart, Silviany Jaramillo Nieves, Leidy Johana Dal Bó, Alexandre Gonçalves Bernardin, Adriano Michael Graduation Program on Materials Science and Engineering Universidade Do Extremo Sul Catarinense CriciúmaSanta Catarina88806000 Brazil

Titanium dioxide (TiO2) is the most used semiconductor for heterogeneous photocatalysis. However, TiO2 is activated only by ultraviolet radiation (wavelength less than 390 nm) and only 5% of the sunlight spectrum corresponds to the UV radiation, therefore restricting the efficiency of titania catalysts. Aiming to obtain more efficient photocatalytic TiO2 nanoparticles under visible light, the goal of this study is the sensitization of this semiconductor with natural dye extracts, consequently enabling the absorption of energy in the visible light spectrum. Four natural dyes were used, blackberry and hibiscus (anthocyanins group) and urucum and curcuma (carotenoids group), which were extracted by the solid-liquid extraction method. The Evonik P25 titanium dioxide was used and the sensitization of the nanoparticles was by the liquid route. Samples were characterized by UV–visible spectrophotometry, differential thermal analysis and thermal gravimetric analysis (DTA/TGA), Fourier-transform infrared spectroscopy (FTIR) and pH control. A solution of curcuma was used to determine the photocatalytic activity of the sensitized TiO2 NPs under visible light. As a result, TiO2 without sensitization degraded only 11% of the dye solution, whereas the sensitized catalysts degraded on a range of 51–73%, showing that sensitized TiO2 nanoparticles have a significant increase in the degradability of organic compounds under visible light. The sensitization of TiO2 nanoparticles with natural dye extract has a great potential to increase the photocatalytic efficiency in the visible spectrum, especially in environments without ultraviolet radiation. © 2020 Elsevier Ltd

关键词： Titanium dioxide

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New low elastic modulus equimassic βeta Ti-Nb-Zr-(Ta-Mo) multiprincipal alloys

Journal of Alloys and Compounds Communications

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Journal of Alloys and Compounds Communications 2024年 4卷

作者： Rafael Formenton Macedo dos Santos Pedro Akira Bazaglia Kuroda Conrado Ramos Moreira Afonso Graduation Program in Materials Science and Engineering (PPG-CEM) Universidade Federal de São Carlos (UFSCar) São Carlos SP 13.565-905 Brazil Department of Materials Engineering (DEMa) Universidade Federal de São Carlos (UFSCar) São Carlos SP 13.565-905 Brazil

The increasing life expectancy, evolving patient demographics, and advancements in implant technologies underscore the need for better biomaterials, particularly alloys with superior mechanical and chemical biocompatibility for biomedical applications like orthopedic implants. β-Ti alloys are promising due to their mechanical properties, including an elasticity modulus (E) of 44–80 GPa, and chemical/biological attributes such as corrosion resistance and osseointegration. This work developed equimassic multicomponent high (HEA) and medium entropy (MEA) β-Ti alloys within the ternary Ti-33Nb-33Zr, quaternary Ti-25Nb-25Zr-25Ta, and quinary Ti-20Nb-20Zr-20Ta-20Mo weight percent systems to achieve an optimized elastic modulus. The study analyzed β-Ti alloys with different β-stabilizing elements, leading to varying entropy levels, and established a relationship between microstructure and properties for enhanced implant efficacy. For the high entropy quinary alloy, increasing the number of alloying elements decreases lattice parameters, increasing the elastic modulus and Vickers microhardness (HV), from 247 HV for the ternary alloy to 453 HV for the quinary alloy. This corresponds to an increase in the entropy degree from 1.041 R to 1.523 R. While a higher entropy degree hinders a low elastic modulus, medium entropy β-Ti alloys such as the quaternary β-Ti-25Nb-25Zr-25Ta alloy achieve an elastic modulus as low as 73 GPa.

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Effects of oxygen availability on Nb-Si multilayer processed by plasma transferred arc

Effects of oxygen availability on Nb-Si multilayer processed...

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materials science and Technology 2019, MS and T 2019

作者： Cardozo, Eloisa Pereira D'Oliveira, Ana Sofia C.M. Post Graduation Program on Materials Science and Engineering Universidade Federal do Paraná Curitiba Paraná Brazil Department of Mechanical Engineering Universidade Federal do Paraná Curitiba Paraná Brazil

ISBN: (纸本)0873397703

The need for higher propulsive and thermal efficiency in high temperature equipment has induced the search for materials that can withstand such harsh operating conditions. Within this group, the Nb-Si alloy system offers an attractive set of properties although they still present a challenge regarding the effects of oxygen. To address the role of processing environment on microstructure and oxidation performance of a Nb-Si multilayer, a powder mixture (Nb37wt%Si) were deposited under an argon atmosphere and in air. NbSi2 and Nb5Si3 were identified in multilayers processed with Nb37wt%Si mixture. The argon atmosphere accounts for changes in phase morphology and also for the enhanced oxidation resistance. This behavior can be accounted for by the high solubility of oxygen on silicides, that contributes to entrap oxygen in multilayers processed in air compromising oxidation performance. © 2019 MS&T19®

关键词： 3D printers

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Decontamination of mobile phones and electronic devices for health care professionals using a chlorhexidine/carbomer 940■gel

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Frontiers of Chemical science and engineering 2019年第1期13卷 192-198页

作者： Rafael Muniz de Oliveira Nereida Mello da Rosa Gioppo Jancineide Oliveirade Carvalho Francilio Carvalho Oliveira Thomas Jay Webster Fernanda Roberta Marciano Anderson Oliveira Lobo University Hospital of the West of Parana State University of West of Parana Cascavel PR Brazil University Center for Health. Humanities and Technology of Piaui (UNINOVAFAPI). Piaui Brazil Science and Technology Institute Brasil University Itaquera SP Brazil Nanomedicine Laboratory Department of Chemical Engineering Northeastern University MA 02115 USA Materials Science and Engineering graduation program Technology Center Federal University of Piaui. PI Brazil

Though they reduce microorganism growth, current hospital disinfectants also damage many of today’s modern electronic devices such as tablets and smartphones. Herein, the efficacy of a new chlorhexidine digluconate gel (CDG) was tested as a disinfectant for mobile and electronic devices in a clinical environment. Specifically, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus were used to infect the screen of eight smartphones. The CDG was prepared at concentrations of 2%, 4% and 6%, and tested on paper disks infected with these bacteria before being tested on the smartphones. The devices were disinfected with the CDG gel (4%) at two times: immediately and after 5 min of the bacterial contamination. In all cases, the CDG gel eliminated 100% of gram-positive and gram-negative microorganisms compared to the control (without any agent). In addition, the gel did not damage the smartphones. Therefore, our study suggests that the CDG gel may be applied to disinfect a wide range of electronic devices for health care professionals in the hospital environment.

关键词： smartphones disinfection clinical environment chlorhexidine bacteria

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Correction to: A mini‑review on plasticrusts: occurrence, current trends, potential threats, and recommendations for coastal sustainability

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Environmental monitoring and assessment 2024年第7期196卷 629页

作者： Minh-Ky Nguyen Md Refat Jahan Rakib Hoang-Lam Nguyen Chitsan Lin Guilherme Malafaia Abubakr M Idris Faculty of Environment and Natural Resources Nong Lam University of Ho Chi Minh City Hamlet 6 Linh Trung Ward Thu Duc City Ho Chi Minh City 700000 Vietnam. Ph.D. Program in Maritime Science and Technology National Kaohsiung University of Science and Technology Kaohsiung 81157 Taiwan. Department of Fisheries and Marine Science Faculty of Science Noakhali Science and Technology University Sonapur Noakhali 3814 Bangladesh. Department of Civil Engineering McGill University Montreal Canada. Ph.D. Program in Maritime Science and Technology National Kaohsiung University of Science and Technology Kaohsiung 81157 Taiwan. ctlin@nkust.edu.tw. Department of Marine Environmental Engineering National Kaohsiung University of Science and Technology Kaohsiung 81157 Taiwan. ctlin@nkust.edu.tw. Post‑Graduation Program in Ecology Conservation and Biodiversity Federal University of Uberlandia Uberlandia MG Brazil. guilhermeifgoiano@***. Post‑Graduation Program in Biotechnology and Biodiversity Federal University of Goias Goiania GO Brazil. guilhermeifgoiano@***. Post‑Graduation Program in Conservation of Cerrado Natural Resources Goiano Federal Institute Urutai GO Brazil. guilhermeifgoiano@***. Department of Chemistry College of Science King Khalid University 62529 Abha Saudi Arabia. Research Center for Advanced Materials Science (RCAMS) King Khalid University 62529 Abha Saudi Arabia.

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Investigation of thermal parameters in numerical modeling of the laser powder bed fusion process for maraging 300 steel

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materials science and engineering: B 2025年 321卷

作者： Bruno Caetano dos Santos Silva Lucas de Figueiredo Soares Luã Fonseca Seixas J.P. Oliveira Jiajia Shen Rodrigo Santiago Coelho Gilmar Ferreira Batalha SENAI CIMATEC SENAI Innovation Institute for Forming and Joining of Materials Av. Orlando Gomes 1845 Piata 41650-010 Salvador-BA Brazil Department of Mechatronics and Mechanical Systems Engineering Polytechnic School of Engineering University of Sao Paulo Av. Prof. Mello Moraes 2231 Butantã Sao Paulo 05508-030 SP Brazil SENAI CIMATEC University Post-Graduation Program MPDS/GETEC/MCTI Av. Orlando Gomes 1845 Piata 41650-010 Salvador-BA Brazil CENIMAT | i3N Department of Materials Science School of Science and Technology NOVA University Lisbon Caparica Portugal

The development of numerical simulations for metal additive manufacturing (AM) processes to predict distortion and residual stress is considered a strategic tool for supporting the industrialization of AM. However, the complexity of these analyses, due to the intricacies of thermal cycles, demands substantial computational resources and a deep understanding of the key process variables to achieve accurate models. This study aims to evaluate the influence of thermal parameters on the results of thermomechanical simulations using the Inherent Strain Method (ISM). Specifically, the analysis investigates the effects of estimated peak temperatures on thermal analyses, distortion, equivalent stress, and microstructure volume fraction in maraging 300 steel (MS300) parts simulated via finite elements. The results indicate that varying the peak temperature of the models causes a linear change in the thermal simulation output, referred to as the exposed energy fraction (EEF) in the Simufact Additive software, which determines the thermal history of the process in fabricated geometry. However, the distortion behavior—by the mechanical analyses that used the EEF as input—deviated from this linearity across specific regions, emphasizing the need for localized accuracy assessment within complex geometries. Equivalent stress decreased with lower peak temperatures, highlighting a correlation between these factors, while the microstructure volume fraction remained unchanged across different peak temperatures. The simulation results were validated by comparing the simulated measurements with experimental data of the same geometry manufactured via laser powder bed fusion (LPBF). Displacement in the simulation was assessed by comparing the diameters of the front and back faces, as well as through surface deviation analysis, which highlighted variations between the scanned experimental geometry and the simulated part. Additionally, the microstructure of the experimental part was examine

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