检索结果-内蒙古大学图书馆

Thermo-optical properties of luminescent carbon dots produced from biomass of Orbignya speciosa (babassu coconut)

Journal of Molecular Liquids 2025年 423卷

作者： Oliveira, Maykol Christian Damasceno Silva, Adriano Almeida Silva-Silva, Tânia Patrícia Silva, Jhaemely Gabrielly Vieira da Silva Júnior, José Ferreira Sanchez, David bell, Maria José Valenzuela Garcia, Hans Anderson Viana, bartolomeu Cruz Terrones, Mauricio Costa, Rubens Silva Santos, Francisco Eroni Paz Physics Department Federal University of Piauí PI 64049550 Brazil Postgraduate Program in Engineering and Materials Science Federal University of 64049550 PI Teresina Brazil Department of Physics and Center for 2-Dimensional and Layered Materials The Pennsylvania State University University ParkPA16802 United States Federal University of Juiz de Fora Institute of Exact Sciences Department of Physics University Campus - UFJF/ ICE/ Department of Physics Martelos MG Juiz de Fora36036330 Brazil Federal Institute of Piauí Paranaíba Campus PI Parnaíba64211145 Brazil

Exploring materials with high nonlinearities derived from organic and biological sources has become a significant focus within the scientific community. Among these materials, carbon dots (CDs) synthesized from biomass have emerged as promising candidates due to their sustainable and cost-effective production methods. This study synthesized CDs from Orbignya speciosa (babassu coconut) biomass via a hydrothermal route. UV–visible absorption and Infrared spectrum analysis revealed characteristic bands associated with the formation of dots and the electronic transitions π–π* from aromatic C=C bonds in the CDs’ core and n–π* transitions of surface carboxylate groups, photoluminescence as a function of temperature and lifetime decay measurements show that the photoluminescence mechanisms in these materials due this transitions comes from electronic indirect transitions from primary sources of the core and carbonyl boundings in the surface of the material, additionally, to this the Dynamic Light Scattering (DLS) and Transmission Electronic Microscopy (TEM) give the structural properties of the dots, amorphous and with a large size distribution with a mean size of (21 ± 1) nm. Thermal lens spectroscopy (TLS) was employed to determine the material's thermal diffusivity, reaching a maximum value of 2.03 × 10−7 m2/s as a function of dilution. The Z-scan technique under continuous wave (CW) excitation at 532 nm investigated nonlinear optical properties, yielding a maximum thermal nonlinear refractive index (n2(th)) value of −5.87 × 10−5 esu. Furthermore, the photothermal efficiency of the CDs was quantified at 505 nm, demonstrating a high absorption efficiency of 94.9 %, suggesting their potential application in photothermal therapies. These findings contribute to understanding babassu coconut CDs’ thermo-optical behavior, highlighting their promise for various practical applications, particularly in biomedicine. © 2025 Elsevier b.V.

关键词： Refractive index

来源：评论

学校读者我要写书评

暂无评论

Spin pumping mechanism in Py/SnTe bilayers: An approach through the magnetoimpedance effect

引用

Journal of Alloys and Compounds 2025年 1031卷

作者： de Morais, A. Souza, E.C. de Silva, A.L. Gamino, M. da Silva, E.F. Ferreira, A. Vaz, F. Lopes, C. bohn, F. Correa, M.A. Postgraduate Program in Materials Science and Engineering Federal University of Rio Grande do Norte RN Natal59078-970 Brazil Physics Department Federal University of Rio Grande do Norte RN Natal59075-000 Brazil Physics Department Federal University of Pernambuco PE Recife50670-901 Brazil University of Minho 4710-057 Portugal LaPMET - Laboratory of Physics for Materials and Emergent Technologies University of Minho 4710-057 Portugal

Different techniques addressing magnetization dynamics are helpful to estimate parameters of a ferromagnetic thin film nanostructure in the field of spintronics, including Gilbert damping parameter (αG), spin pumping contributions (αSP), two magnons scattering (αTMS), spin mixing conductance (Geff) and others. When considering a bilayer structure, the non-ferromagnetic layer effects need to be carefully selected to tailor an effective spintronic response. Here, the magnetization dynamics are explored in Ni81Fe19(Py)/Ag and Ni81Fe19(Py)/SnTe nanostructures and report the spin mixing conductance from magnetoimpedance experiments. The results are interpreted by considering structural and magnetic characterizations. The spin mixing conductance is estimated as Geff (Py/Ag) = 1.13×1014 cm−2 and Geff (Py/SnTe) = 18.05 ×1014 cm−2, revealing the significant enhancement of Geff when the SnTe acts as a cap layer, indicating that SnTe is a good spin sink. © 2025 Elsevier b.V.

关键词： Ferromagnetism

来源：评论

学校读者我要写书评

暂无评论

Influence of submerged arc welding slag content variation on cementitious materials: A sustainable alternative

引用

Construction and building materials 2025年 483卷

作者： Castro-Lopes, S. Rodrigues, V.D. Marden, Sandro Peña-Garcia, R. Padrón-Hernández, E. berenguer, Romildo Federal Institute of Education Science and Technology of Pará PA Altamira Brazil Laboratory of Composite Materials and Structural Integrity Corrosion and Biocorrosion - CompoLab/LBC Federal University of Pernambuco PE Recife Brazil Federal University of Paraiba Department of Mechanical Engineering PB Joao Pessoa Brazil Federal Rural University of Pernambuco Postgraduate Program in Physics Engineering Academic Unit of Cabo de Santo Agostinho Cabo de Santo PE Agostinho Brazil Federal University of Pernambuco Department of Physics PE Recife Brazil Polytechnic School University of Pernambuco PE Recife Brazil Federal University of Pernambuco Department of Mechanical Engineering PE Recife Brazil

This study evaluates the effects of submerged arc welding (SAW) slag as a partial replacement for Portland cement in cementitious materials. Cement pastes with 5 %, 10 %, 15 %, 20 %, 25 %, and 30 % SAW slag were tested for compressive strength, tensile strength, carbonation resistance, phase formation, and environmental impact. The results revealed that up to 10 % SAW slag significantly enhanced compressive strength, with the 5 % replacement showing a 20.10 % increase in strength at 28 days compared to the control. The mechanical improvement was attributed to the formation of the CSH phase, which was confirmed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Carbonation tests indicated that the 5 % SAW samples reduced carbonation by 5 % compared to the control, while the 10 % SAW samples showed a 1 % reduction. This suggests that SAW slag enhances the resistance of cementitious materials to CO2 attack, improving long-term durability. XRD analysis also identified an increase in amorphous phases in the SAW samples, particularly in the 5 % addition, further supporting the pozzolanic activity of SAW slag. Pozzolanic effectiveness coefficient analysis revealed synergistic effects for SAW slag blends, with optimal performance observed at 5 % replacement, in line with microstructural evidence of enhanced CSH gel formation. Environmental analysis demonstrated that replacing 10 % of Portland cement with SAW slag could reduce CO2 emissions by approximately 4564 kg annually, while a 15 % replacement could lead to a reduction of 6846 kg of CO2. These results underscore the potential of SAW slag as a sustainable and performance-enhancing alternative to conventional cement in concrete production. © 2025 Elsevier Ltd

关键词： Compressive strength

来源：评论

学校读者我要写书评

暂无评论

Computational Characterization of the Recently Synthesized Pristine and Porous 12-Atom-Wide Armchair Graphene Nanoribbon

arXiv

引用

arXiv 2025年

作者： da Gomes, Djardiel S. Felix, Isaac M. Radel, Willian F. Dias, Alexandre C. Ribeiro Junior, Luiz A. Pereira Junior, Marcelo L. State University of Campinas Gleb Wataghin Institute of Physics Department of Applied Physics Campinas São Paulo13083-859 Brazil University of Brasília Faculty UnB Planaltina Materials Science Postgraduate Program Federal District Brasília Brazil Center for Agri-food Science and Technology Federal University of Campina Grande Paraíba Pombal58840-000 Brazil University of Brasília Institute of Physics Physics Postgraduate Program Federal District Brasília70910900 Brazil Institute of Physics International Center of Physics University of Brasília Federal District Brasília70910-900 Brazil Institute of Physics University of Brasília Federal District Brasília70910-900 Brazil Computational Materials Laboratory University of Brasília Federal District Brasília70910900 Brazil University of Brasília College of Technology Department of Electrical Engineering Federal District Brasília70910-900 Brazil

Recently synthesized Porous 12-Atom-Wide Armchair Graphene Nanoribbons (12-AGNRs) [Nano Lett. 2024, 24, 10718-10723]exhibit tunable properties through periodic porosity, enabling precise control over their electronic, optical, thermal, and mechanical behavior. This work presents a comprehensive theoretical characterization of pristine and porous 12-AGNRs based on density functional theory (DFT) and molecular dynamics (MD) simulations. DFT calculations reveal substantial electronic modifications, including band gap widening and the emergence of localized states. Analyzed within the bethe–Salpeter equation (bSE) framework, optical properties highlight strong excitonic effects and significant absorption shifts. Thermal transport simulations indicate a pronounced reduction in conductivity due to enhanced phonon scattering at nanopores. At the same time, MD-based mechanical analysis shows decreased stiffness and strength while maintaining structural integrity. Despite these modifications, porous 12-AGNRs remain mechanically and thermally stable. These findings establish porosity engineering as a powerful strategy for tailoring graphene nanoribbons’ functional properties, reinforcing their potential for nanoelectronic, optoelectronic, and thermal management *** Codes 00-xx © 2025, CC bY.

关键词： Nanoribbons

来源：评论

学校读者我要写书评

暂无评论

Synthesis and characterization of ba and Sr celsian ceramics from zeolites obtained from amazonian bauxite waste clay

引用

Applied Clay science 2025年 275卷

作者： Nayara Aparecida Fonseca Couto bruno Apolo Miranda Figueira Igor Alexandre Rocha barreto Patricia Teresa Souza da Luz Oscar Jesus Choque Fernandez Marcondes Lima da Costa Postgraduate Program in Materials Engineering Federal Institute of Education Science and Technology of Pará 66093-020 Belém Brazil Institute of Geosciences Federal University of Pará 66075-110 Belém Brazil

This study explored the use of bauxite washing clay (bWC), a mining residue from the Amazon region, as a raw material for the synthesis of zeolites, followed by their conversion into barium and strontium celsian ceramics. The bWC, rich in gibbsite and kaolinite, demonstrated significant potential due to its high aluminum and silicon content. Zeolites were synthesized through alkaline activation with 1 M NaOH at 350 °C for 4 h, followed by hydrothermal treatment at 100 °C for 24 h. Ion exchange with ba 2+ and Sr 2+ cations was then performed, and the obtained materials were thermally treated at 1200 °C. The results showed the formation of monoclinic barium celsian with high crystallinity, while Sr-celsian exhibited partial conversion, retaining nepheline as a secondary phase. Monoclinic barium celsian exhibited superior mechanical properties, achieving a compressive strength of 15.9 MPa in compositions with lower silica content, whereas Sr-celsian reached 11.94 MPa. In conclusion, this study highlights the potential of bWC as a valuable and sustainable precursor for advanced ceramic production.

关键词：

来源：评论

学校读者我要写书评

暂无评论

TIME AND POLING HISTORY DEPENDENT ENERGY STORAGE AND DISCHARGE bEHAVIORS IN POLY(VINYLIDENE FLUORIDE-CO-HEXAFLUOROPROPYLENE) RANDOM COPOLYMERS

引用

Chinese Journal of Polymer science 2011年第1期29卷 65-80页

作者： Fang-xiao Guan Jing Wang Ji-lin Pan Qing Wang Lei Zhu Polymer Program Institute of Materials Science and Department of Chemical Materials and Biomolecular Engineering University of Connecticut Storrs Connecticut 06269-3136 USA b Department of Materials Science and Engineering Pennsylvania State University University Park Pennsylvania 16802 USA Department of Maeromolecular Science and Engineering Case Western Reserve University Cleveland Ohio 44106-7202 USA

We studied cycle time （0.01-10 s with triangular input waves） and poling history （continuous versus fresh poling） dependent electric energy storage and discharge behaviors in poly（vinylidene fluoride-co-hexafluoropropylene） [P（VDF- HFP）] films using the electric displacement -- the electric field （D-E） hysteresis loop measurements. Since the permanent dipoles in PVDF are orientational in nature, it is generally considered that both charging and discharging processes should be time and poling history dependent. Intriguingly, our experimental results showed that the charging process depended heavily on the cycle time and the prior poling history, and thus the D-E hysteresis loops had different shapes accordingly. However, the discharged energy density did not change no matter how the D-E loop shape varied due to different measurements. This experimental result could be explained in terms of reversible and irreversible polarizations. The reversible polarization could be charged and discharged fairly quickly （〈 5 ms for each process）, while the irreversible polarization depended heavily on the poling time and the prior poling history. This study suggests that it is only meaningful to compare the discharged energy density for PVDF and its copolymer films when different cycle times and poling histories are used.

关键词： P（VDF-HFP） random copolymer Charging and discharging behaviors Time and poling history dependence Dipole switching Compensation polarization.

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Effect of dual modification on structural, functional and dielectric properties of cassava starch

Food Physics

引用

Food Physics 2025年 2卷

作者： Cremasco, Paula Figueiredo M. Siqueira, Karine Mayuri Pistoni Sobral, Paulo José do Amaral Velloso, Walter Ferreira de Lima, César Gonçalves Gut, Jorge Andrey Wilhelms Moraes, Izabel Cristina Freitas Postgraduate Program in Materials Science and Engineering Faculty of Animal Science and Food Engineering University of São Paulo Avenue Duque de Caxias Norte São Paulo Pirassununga 13635900 Brazil Department of Biossistems Engineering Faculty of Animal Science and Food Engineering University of São Paulo Avenue Duque de Caxias Norte São Paulo Pirassununga 13635900 Brazil Department of Food Engineering Faculty of Animal Science and Food Engineering University of São Paulo Avenue Duque de Caxias Norte São Paulo Pirassununga 13635900 Brazil Food Research Center (FoRC) University of São Paulo Lake Street São Paulo São Paulo 05508-080 Brazil Departament of Basic Sciences Faculty of Animal Science and Food Engineering University of São Paulo Avenue Duque de Caxias Norte São Paulo Pirassununga 13635900 Brazil Department of Chemical Engineering Polytechnic School University of São Paulo Lake Street São Paulo São Paulo 05508-080 Brazil

The combined effect of hydrocolloid addition and microwave heating on the structural, physical and functional properties of cassava starch remains underexplored, despite individual studies on these modification methods. The dielectric properties, important for the microwave treatment of starch, have received little attention in recent studies. Cassava starch with and without addition of hydrocolloids (guar and xanthan gums) was modified by microwave heating for two different exposure times, and its structural, functional, and dielectric properties were studied. The dual modification enhanced the swelling power and oil holding capacity of the starch, reduced its gelatinization temperature, and did not alter its crystallinity. Notably, xanthan-modified starch microwaved for 6 min exhibited higher color variation (ΔE*) and increased granules agglomeration, while the microwave treatment alone roughened the surface of the starch granules. The mean diameters D[4,3] of starch increased with xanthan gum addition, microwave treatment (6 min), and their combination. The relative permittivity (ε’), loss factor (ε”) and penetration depth (Db>p)b> were lower for samples modified by the combined method. Considering the type of hydrocolloid and the microwave exposure time, the combined modification significantly influenced the properties of starch, offering a promising approach to producing starch with enhanced functional properties. © 2024 KeAi Communications Co., Ltd

关键词： biopolymers Cassava starch Guar Microwave Xanthan

来源：评论

学校读者我要写书评

暂无评论

Methane reforming reactions for hydrogen production using hydrotalcite precursors and nanofibers based catalysts 12

Methane reforming reactions for hydrogen production using hy...

引用

12th International Renewable Energy Congress, IREC 2021

作者： Silva, Thamyscira Chaghouri, Muriel Tidahy, Lucette Haingomalala Gennequin, Cedric Abi-Aad, Edmond Cesario, Moises MacEdo, Daniel Dunkerque France Federal University Of Paraiba Materials Science And Engineering Postgraduate Program Joao Pessoa Brazil

ISBN: (纸本)9781665432900

CoNiMg4Al2 catalysts were synthesized using two different methods: solution blow spinning to produce nanofibers (NF), and co-precipitation to produce hydrotalcite precursors (HT). Part of the hydrotalcite sample was ground (GR) using mechanical milling to determine the effect of grinding on the catalytic performance. The three materials (NF, HT and GR) were tested in the dry and steam reforming of methane (DRM, SRM respectively) reactions during 12h stability tests at 700°C. The calcined and the used catalysts were characterized using XRD and DTA/TG analysis. All catalysts were active during the SRM and DRM tests;however, nanofibers showed a slightly higher activity in both reactions. The dry reforming of methane reaction was more susceptible to the formation of carbon deposition leading to the deactivation of the ground catalyst. © 2021 IEEE.

关键词： Methane

来源：评论

学校读者我要写书评

暂无评论

Polymer blends of poly(lactic acid) and starch for the production of films applied in food packaging: A brief review

引用

Polymers from Renewable Resources 2023年第2期14卷 108-153页

作者： Carneiro da Silva, Lucas Rafael Rios, Alessandro de Oliveira Campomanes Santana, Ruth Marlene Postgraduate Program in Mining Metallurgical and Materials Engineering Laboratory of Polymeric Materials Federal University of Rio Grande do Sul Rio Grande do Sul Brazil Postgraduate Program in Food Science and Technology Laboratory of Bioactive Compounds Federal University of Rio Grande do Sul Rio Grande do Sul Brazil

The limited degradation of synthetic polymers used in food packaging when discarded in the environment is a major concern for society. Therefore, industry and academia have sought to develop biodegradable and eco-friendly materials for single-use in packaging. An interesting alternative for the food industry is biodegradable polymeric films, which is why different biopolymers have been used in the production of sustainable packaging. It is worth mentioning that the use of biodegradable polymers is one of the most successful innovations in the industry to address issues related to the environment. Among the available raw materials, starch extracted from different renewable sources is very promising for this purpose, due to its abundance, low-cost compared to other polymers and ability to produce non-toxic films. However, when used alone, pure starch has many limitations, which can be overcome by developing a mixture with other polymers (polymer blends), preferably from renewable and biodegradable sources, such as poly(lactic acid) (PLA). In this context, the absence of literature reviews evidencing the results of the application of films in foods led us to write this article, given the importance of polymer blends produced with different types of starch (cassava, corn, pea, potato, rice and wheat) and the PLA matrix. According to the results, it is clear that polymer blends based on PLA/Starch for food packaging are very promising, already being part of the industries solutions, aiming to minimize the large volume of plastic waste of petrochemical origin discarded in nature. Obviously, as with any technology, more research is needed to further improve the performance of the films, and while much research has made great strides, there are still limitations that prevent the commercialization of these materials. © The Author(s) 2023.

关键词： Starch

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：