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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

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 preparation of pharmaceutical β-Cd inclusion complexes in a solid form.

关键词： Bergenin Chromatography Yield Active loss Solubility

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

Gravitational waves from compact objects

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Research in Astronomy and Astrophysics 2010年第11期10卷 1071-1099页

作者： José Antonio de freitas Pacheco University of Nice-Sophia Antipolis Observatoire de la Cote d'Azur Laboratoire Cassiopée-UMR 6202 BP 4229-F606304-Nice Cedex 4-France

Large ground-based laser beam interferometers are presently in operation both in the USA （LIGO） and in Europe （VIRGO） and potential sources that might be detected by these instruments are revisited. The present generation of detectors does not have a sensitivity high enough to probe a significant volume of the universe and, consequently, predicted event rates are very low. The planned advanced generation of interferometers will probably be able to detect, for the first time, a gravitational sig- nal. Advanced LIGO and EGO instruments are expected to detect few （some）： binary coalescences consisting of either two neutron stars, two black holes or a neutron star and a black hole. In space, the sensitivity of the planned LISA spacecraft constellation will allow the detection of the gravitational signals, even within a ＂pessimistic＂ range of possible signals, produced during the capture of compact objects by supermassive black holes, at a rate of a few tens per year.

关键词： gravitational waves -- neutron stars -- black holes

Recycling of spent lithium-ion batteries as a sustainable solution to obtain raw materials for different applications

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Journal of Energy Chemistry 2023年第4期79卷 118-134页

作者： V.M.Leal J.S.Ribeiro E.L.d.Coelho M.B.J.G.freitas Federal University of Espírito Santo Department of ChemistryLaboratory of Electrochemistry and ElectrochemistryAv.Fernando Ferrari514VitóriaES 29075-910Brazil

Lithium-ion batteries(LIBs)containing graphite as anode material and LiCoO_(2),LiMn_(2)O_(4),and LiNi_(x)Mn_(y)Co_(z)O_(2) as cathode materials are the most used worldwide because of their high energy density,capacitance,durability,and ***,such widespread use implies the generation of large amounts of electronic *** is estimated that more than 11 million ton of LIBs waste will have been generated by *** recycling can contribute to minimizing environmental contamination and reducing production costs through the recovery of high-value raw materials such as lithium,cobalt,and *** most common processes used to recycle spent LIBs are pyrometallurgical,biometallurgical,and *** the current scenario,it is necessary to develop environmentally friendly methods to recycle batteries and synthesize materials with multiple technological *** study presents a review of industrial and laboratory processes for recycling spent LIBs and producing materials that can be used in new batteries,energy storage devices,electrochemical sensors,and photocatalytic reactions.

关键词： Li-ion batteries Recycling Cathode Battery Hydrometallurgical Pyrometallurgical

Flexible neural probes:a review of the current advantages,drawbacks,and future demands

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第2期25卷 153-167页

作者： Sara PIMENTA Joao R.freitas JoséH.CORREIA CMEMS-UMinho University of MinhoGuimarães4800-058Portugal LABBELS-Associate Laboratory Braga/GuimarãesPortugal

Brain diseases affect millions of people and have a huge social and economic *** use of neural probes for studies in animals has been the main approach to increasing knowledge about neural network ***,neuroscientists are trying to develop new and more effective therapeutic approaches to treating neurological *** implementation of neural probes with multifunctionalities(electrical,optical,and fluidic interactions)has been increasing in the last few years,leading to the creation of devices with high temporal and spatial *** the applicability of,and elements integrated into,neural probes has also led to the necessity to create flexible interfaces,reducing neural tissue damage during probe implantation and increasing the quality of neural acquisition *** this paper,we review the fabrication,characterization,and validation of several types of flexible neural probes,exploring the main advantages and drawbacks of these ***,future developments and applications are ***,this review aims to present the currently available flexible devices and future appropriate avenues for development as possible guidance for future engineered devices.

关键词： Brain knowledge Flexible interface Multifunctional probe

Equilibrium, thermodynamic, and kinetic of Cr(VI) adsorption using a modified and unmodified bentonite clay

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International Journal of Mining Science and Technology 2014年第4期24卷 525-535页

作者： d.J.L. Guerra I. Mello L.R. freitas R. Resende R.A.R. Silva department of Mineral Resources University Federal of Mato Grosso DRM-UFMT Mato Grosso 78060900 Brazil

The capacities of natural and modified Brazilian bentonite samples as adsorbents to remove hexavalent metal chromium were investigated under several conditions in batch and column methods. The raw material, Ca-bentonite, was modified by anchorament of 3-aminopropyltrietoxisilane （APS） and 3,2- aminoethylaminopropyltrimetoxisilane （AEAPS） in the surface of bentonite sample： This type of new occurrence of bentonite is suitable as a raw material for adsorption process. Adsorption behavior of three bentonite types was strongly depending on pH of adsorbate solution, contact time adsorbent/adsorbate, and initial concentration of Cr（VI）. The results were confirmed by column method and reveals that the adsorption process of materials accorded by the Redlich-Peterson, Sips, dubinin-Radushkevich, and tang- muir isotherm models. The exothermic entbalpic values reflected a favorable energetic process for chro- mium ions anchored in the material surfaces. The negative Gibbs free energy results supported the spontaneity of three adsorption reactions with Cr（VI） ions.

关键词： Bentonite Organo-bentonite Chromium Equilibrium Kinetic Adsorption

Experimental statistic design applied for obtaining Zn:xCe by microwave-assisted hydrothermal method with photocatalytic property

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Journal of Advanced Ceramics 2016年第2期5卷 103-110页

作者： Y.F.GOMES A.K.freitas R.M.NASCIMENTO M.R.d.BOMIO C.A.PASKOCIMAS F.V.MOTTA departamento de Engenharia de Materiais Universidade Federal do Rio Grande do Norte 59078-900 Natal/RN Av.Sen.Salgado Filho 3000 CEP 59072-970 Brazil

In this study, the nanostructures of pure ZnO and ZnO:xCe3+ were prepared using statistic design—factorial design 3(3?1)?3-level and mixed-level factorials and fractional with replicates in the central point, totaling 11 experiments. The experiments were performed using the microwave-assisted hydrothermal (MAH) method with Ce3+ concentration of 2 and 4 mol% at 60, 110, and 160 °C for 10, 20, and 30 min. X-ray diffraction (XRd), scanning electron microscopy (SEM), and optical diffuse reflectance were used to characterize the products. The fractional factorial design indicated the optimal design area, and the studies were continued by ridge analysis. The analysis of variance (ANOVA), the Pareto, and the model adjusted to the conditions proposed in this study due to the determination coefficient of 99.9%, variance (R 2), and response surface generated were satisfactory, thus having an optimization in the process of obtaining ZnO doped with Ce.

关键词： hydrothermal ZnO cerium photocatalytic activity factorial design 3(3-1)

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