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Magnetic Tunnel Junction Based on MgO Barrier prepared by Natural Oxidation and Direct Sputtering Deposition

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Nano-Micro Letters 2012年第1期4卷 25-29页

作者： Xiaohong Chen paulo.p.freitas Engineering Research Center for Nanophotonics and Advanced Instrument Ministry of Education Department of Physics East China Normal University INESC-MN

Magnetic tunnel junctions(MTJs) based on MgO barrier have been fabricated by sputtering single crystal MgO target and metal Mg target, respectively, using magnetic sputtering system Nordiko 2000. MgO barriers have been formed by a multi-step deposition and natural oxidization of Mg layer. Mg layer thickness,oxygen flow rate and oxidization time were adjusted and the tunnel magnetoresistance(TMR) ratio of optimal MTJs is over 60% at annealing temperature 385. The(001) MgO crystal structure was obtained when the separation distance between MgO target and substrate is less than 6 cm. The TMR ratio of most MgO based MTJs are over 100% at the separation distance of 5 cm and annealing temperature 340. The TMR ratios of MTJs are almost zero when the separation distance ranges from 6 to 10 cm, due to the amorphous nature of the MgO film.

关键词： Magnetic tunnel junctions Mg O Crystal structure Magnetic sputtering system

The initial stages of Li_(2)O_(2) formation during oxygen reduction reaction in Li-O_(2) batteries:The significance of Li_(2)O_(2) in charge-transfer reactions within devices

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Journal of Energy Chemistry 2024年第1期88卷 223-231,I0006页

作者： Daniela M.Josepetti Bianca p.Sousa Simone A.J.Rodrigues Renato G.freitas Gustavo Doubek Advanced Energy Storage Division LABCenter for Innovation on New EnergiesSchool of Chemical EngineeringUniversity of CampinasAv Albert Einstein 50013083-852CampinasSPBrazil Institute of physics&Department of Chemistry Laboratory of Computational MaterialsFederal University of Mato Grosso78060-900CuiabáMTBrazil

Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion ***,this theoretical characteristic has not yet been converted into a real device with high *** with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further *** this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic *** solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time *** the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more *** model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge ***,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode *** methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

关键词： Li-O_(2)battery Operando Raman analysis Equivalent circuit modeling Time-constant distribution

Rice spouted bed for manufacturing inclusion complexes of Endopleura uchi L extracts in β-cyclodextrin

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particuology 2019年第1期17卷 208-215页

作者： L.V.D. freitas A.C.R. Montes E.I.A. Campos E.C. Conceicao L.A. Tacon A.D. Lanchote L.A.p.freitas Faculdade de Ciencias Farmaceuticas de Ribeirao preto University of Sao PauloVia do Cafe s/n14040-903Ribeirao PretoSPBrazil

Uxi (Endopleura uchi) is a plant from the Brazilian Amazon. It has many biological activities that are attributed to its main active component, bergenin (BG), which has low water solubility. The aim of this work was to obtain β-cyclodextrin (β-CD) inclusion complexes of uxi using lyophilized cooked rice as the solid substrate. The process was studied using a Box–Behnken design with the solution feed rate, molar ratio of β-CD to BG, and rice bed load as factors. These factors greatly affected the product bulk density, angle of repose, water content, and BG content, loss, and water solubility. The optimum process conditions determined using a desirability functions methodology were an extract feed rate of 1 mL/min, a ratio of β-CD to BG of 3:1, and a substrate load of 100 g. The predicted values under the optimum conditions were close to the experimental results of a water content of 5.8%± 0.2%, BG content of 985.7 ± 15.4 μg/g, BG water solubility of 2230.2 ± 21.1 μg/mL, and BG loss of 1.2%± 0.1%. These results confirm that spouted beds are an important tool for rapid, one-step.p.eparation of pharmaceutical β-CD inclusion complexes in a solid form.

关键词： Bergenin Chromatography Yield Active loss Solubility

The transformation of agriculture in Brazil through development and adoption of Zero Tillage Conservation Agriculture

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International Soil and Water Conservation Research 2014年第1期2卷 35-46页

作者： p.L.de freitas J.N.Landers Brazilian Agricultural Research Corporation-National Centre for Soil Research(Embrapa Soils) Agronomist M.Sc.Hon.DirectorZero Tillage Farmers’Association for the Cerrado Region of Brazil

The soil conservation movement in Brazil has been a major driving force in the continuing search for agricultural farming systems that are more sustainable than what we have today,particularly in tropical and subtropical *** development and adoption of Zero Tillage Conservation Agriculture(ZT/CA)was the key to the success of this movement,generating agricultural,environmental,and societal *** of the ZT/CA philosophy and technologies is currently practiced on more than 50%of the annual crop *** is due to the work and innovations of pioneering farmers,agronomists,researchers,and consultants that were and are involved in these *** extensive adoption of ZT/CA occurred after many unsuccessful efforts to mitigate against the devastating effects of soil erosion that were threatening the entire agricultural industry in *** and farmers realized that erosion control required continual cover of the soil to guard against the torrential rain storms common to these *** triggered the efforts of soil conservation pioneers at different points in time and regions of *** southern Brazil,Herbert Bartz,watched his topsoil eroding away in torrents of *** set him thinking and searching for alternatives,resulting in his adoption of ZT/CA farming in *** years later in Brazil’s centre-western savannah(Cerrado biome),farmers,researchers,crop consultants and agro-industry initiated efforts to expand cultivation into the very difficult production region of the *** was successfully achieved through the pioneering work of agronomist John Landers,bringing experience from the ZT/CA farmer association networks in the *** were the turning points in the sustainable development of annual crop farming in ***,society recognizes the role of these pioneers as key to achieving social,economic and environmental ***/CA reversed the historically accelerating degradation of soil organic matter

关键词： Soil conservation Zero tillage Conservation agriculture Sustainable soil management Soil organic matter

Inclusive housing program： The case of Oe-Cusse region in East Timor

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Frontiers of Architectural Research 2017年第1期6卷 74-88页

作者： Miguel p. Amadoa Ines Ramalhete Antonio Ribeiro Amado Joao C. freitas CERIS - Civil Engineering Research and Innovation for Sustainability IST Universidade de Lisboa Lisboa 1049-001 Portugal GEOTpU LAB Instituto Superior Tecnico Universidude de Lisboo Lisboo 1049-001 Portugul CCIAUD Faculty of Architecture Universidude de Lisboo Lisboo 1049-001 Portugal

Housing development has become one of the main strategies to alleviate impoverished communities in developing countries. In the past, policies and programs focused on either economic or social aspects, and numerous imported solutions had failed to produce satisfactory results. At present, holistic approaches integrating all dimensions of human activity and environmental impact are gaining recognition as suitable alternatives for various experiences in developing nations. However, these approaches do not properly consider the local context, which is different for each case, thereby leading to inadequate models and unsuccessful implementations. This p.p.r presents a context-driven and integrated approach for rural areas in developing nations for one of the most basic human endeavors, i.e., constructing a house. The self-building process utilized in constructing houses is a major strategy to help communities overcome poverty. Such a house must be capable of accommodating economic activities; must be durable yet flexible in layout and size; and must offer all basic services, including water, sanitation, and energy. Consequently, the Inclusive Housing program is developed and employed in Oe-Cusse, a remote region of East Timor, as an integral part of the Regional plan.

关键词： Developing countries Rural settlements Housing program Adaptive housing

prevascularized spongy-like hydrogels maintain their angiogenic potential after prolonged hypothermic storage

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Bioactive Materials 2024年第7期37卷 253-268页

作者： Sara freitas-Ribeiro Helena Moreira Lucília p.da Silva Jennifer Noro Belem Sampaio-Marques paula Ludovico Mariana Jarnalo Ricardo Horta Alexandra p.Marques Rui L.Reis Rogerio p.p.rraco B’s Research Group I3Bs-Research Institute on BiomaterialsBiodegradables and BiomimeticsUniversity of MinhoHeadquarters of the European Institute of Excellence on Tissue Engineering and Regenerative MedicineAveParkParque de Ciencia e TecnologiaZona Industrial da Gandra4805-017BarcoGuimaraesPortugal ICVS/3B’s-pT Government Associate Laboratory Braga/GuimaraesPortugal Life and Health Sciences Research Institute(ICVS) School of MedicineUniversity of MinhoBragaPortugal Department of plastic and Reconstructive Surgery and Burn UnityCentro Hospitalar de Sao JoaoPortoPortugal Faculty of Medicine-University of porto Portugal

The chronic shortage of organs and tissues for transplantation represents a dramatic burden on healthcare systems *** engineering offers a potential solution to address these shortages,but several challenges remain,with prevascularization being a critical factor for in vivo survival and integration of tissue engineering ***,a different challenge hindering the clinical implementation of such products,regards their efficient preservation from the fabrication site to the *** has emerged as a potential solution for this issue due to its milder effects on biologic systems in comparison with other cold preservation *** impact on prevascularization,however,has not been well *** this work,3D prevascularized constructs were fabricated using adipose-derived stromal vascular fraction cells and preserved at 4◦C using Hypothermosol or basal culture media(α-MEM).Hypothermosol efficiently preserved the structural and cellular integrity of prevascular networks as compared to constructs before *** contrast,the use ofα-MEM led to a clear reduction in prevascular structures,with concurrent induction of high levels of ap.p.osis and autophagy at the cellular *** vivo evaluation using a chorioallantoic membrane model demonstrated that,in opposition toα-MEM,Hypothermosol preservation retained the angiogenic potential of constructs before preservation by recruiting a similar number of blood vessels from the host and presenting similar integration with host *** results emphasize the need of studying the impact of preservation techniques on key properties of tissue engineering constructs such as prevascularization,in order to validate and streamline their clinical application.

关键词： Tissue engineering prevascularization Hypothermic preservation Clinical translation

pharmaceutical applications of spouted beds: A review on solid dosage forms

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particuology 2019年第1期17卷 126-136页

作者： Luis Alexandre pedro de freitas Faculdade de Ciencias Farmaceuticas de Ribeirao preto University of Sao PauloVia do Cafe s/n. Campus USPRibeirao Preto14040-903Sao Paulo. Brazil

Spouted beds (SBs) have a long history of successful applications for preparation of solid dosage forms of pharmaceuticals. The well-known versatility of SBs, provided by different design and operational factors, and their efficient mixing of solids allow for engineering of technological characteristics of pharmaceutical solid forms. particle properties like morphology, size, porosity, flowability, and dissolution rate can be improved by managing geometric and operational conditions for spouting. Drying is probably the most disseminated operation for pharmaceutical processing in SBs, and many studies have investigated drying of medicinal plant extracts such as achiote (Bixa orellana sp.), guarana (paullinia cupana sp.), passion flower (passiflora alata D.), and rosemary (Rosmarinus officinalis L.) with excellent pharmacotechnical and stability results. Another important application is coating of tablets and gelatin capsules, and previous studies have shown that SBs and spout–fluid beds may be advantageous over traditional pan coating, especially for polymeric film coating. Recently, an alternative process for improving drug bioavailability has involved preparation of β-cyclodextrin inclusion complexes in SBs. The first study to propose SBs for this pharmaceutical application explored the advantage of obtaining solid forms of inclusion complexes in just one step, and obtained expressive increases in drug solubility. The technique has been applied in subsequent studies on inclusion complexes of the medication carvedilol and uxi (Endopleura uchi L.) extracts.

关键词： Coating Drying Granulation Inclusion Microencapsulation

Nonformal environmental education:a case study with farmers in a town of the South Minas Gerais state,Brazil

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Chinese Journal of p.p.lation,Resources and Environment 2015年第4期13卷 324-331页

作者： Mirlaine R.freitas Stella V.B.G.Matias Renato L.G.Macedo Matheus p.freitas Nelson Venturin Department of Forest Science Federal University of Lavras Department of Chemistry Federal University of Lavras

Brazil is a central place in the international agricultural markets and this fact has been demanding environmentally oriented agricultural practices by Brazilian farmers and professionals involved in the agricultural market chain.A concise and structured questionnaire was applied to obtain the environmental perception of a group of Brazilian farmers in a town of the south Minas Gerais state,using herbicides as the topic for a case study.A highly variable opinion about taking the environment into account when choosing the most appropriate herbicide was ***,efficacy has been indicated as the most important factor when choosing an herbicide,followed by the environment and *** outcomes from the questionnaires,*** insufficient conception and importance given to environment when choosing the herbicide,motivated the creation of a teaching-learning model for the nonformal environmental education using the concept of socio-ecological *** routine puts in practice the resilience thinking currently invoked as a major tool to achieve the conservation of the socio-ecological system,as well as it is complimentary to the outcome-oriented optimization for conservation *** the case study about farmers and the use of herbicides,we conclude that a complex reasoning and,ultimately,pro-environmental actions can be improved after experiencing the recommended model for environmental education.

关键词： environmental perception farmers herbicides resilience thinking socio-ecological system

Oxidative reforming of methane for hydrogen and synthesis gas production:Thermodynamic equilibrium analysis

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Journal of Natural Gas Chemistry 2012年第5期21卷 571-580页

作者： Antonio C.D.freitas Reginaldo Guirardello School of Chemical Engineering University of Campinas (UNICAMP)Av.Albert Einstein 50013083-852Campinas-SPBrazil

A thermodynamic analysis of methane oxidative reforming was carried out by Gibbs energy minimization （at constant pressure and temperature） and entropy maximization （at constant pressure and enthalpy） methods,to determine the equilibrium compositions and equilibrium temperatures,*** cases were treated as optimization problems （non-linear programming formulation）.The GAMS 23.1 software and the CONOpT2 solver were used in the resolution of the proposed *** hydrogen and syngas production were favored at high temperatures and low pressures,and thus the oxygen to methane molar ratio （O 2 /CH 4） was the dominant factor to control the composition of the product *** O 2 /CH 4 molar ratios higher than 0.5,the oxidative reforming of methane presented autothermal behavior in the case of either utilizing O 2 or air as oxidant agent,but oxidation reaction with air possessed the advantage of avoiding peak temperatures in the system,due to change in the heat capacity of the system caused by the addition of *** calculated results were compared with previously published experimental and simulated data with a good agreement between them.

关键词： thermodynamic analysis methane oxidative reforming Gibbs energy minimization entropy maximization hydrogen and syngas production