Design of Nickel Supported on Water-Tolerant Nb2O5 Catalysts for the Hydrotreating of Lignin Streams Obtained from Lignin-First Biorefining

R.R. acknowledges the financial support provided by the ERC Consolidator Grant LIGNINFIRST (Project Number: 725762). R.R. and A.A.S.C. thank FAPESP for the support provided (Process Number: 2016/50423-3). The authors are grateful to LNLS/CNPEM for the infrastructure (XPD beamline and chemistry laboratory), LNNano for the STEM infrastructure, the GPMMM laboratory (IQ-UNICAMP) for the quantitative FTIR of adsorbed pyridine analysis, CNPq for the PhD scholarship (Process Number: 165106/2014-0), and CAPES for the PDSE scholarship (Process Number: 88881.132245/2016-01). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. Finally, the authors are thankful to CBMM for the ammonium niobium oxalate hydrate samples.Peer reviewedPublisher PD

Estruturas de fluxo em uma camara cilindrica de fundo rotatorio : construção, caracterização e experimentos com soluções polimericas

Orientador: Edvaldo SabadiniDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestrad

Topoquimica de filmes de particulas de latex de Poli(estireno-co-acrilamida)

Resumo: Esta tese demonstra efeitos da microquímica de partículas de látex sobre a formação de filmes e monocamadas de partículas de poli(estireno-co-acrilamida) (PS-AAM) usando técnicas microcópicas. O látex foi fracionado por sedimentação sob gravidade produzindo três frações de partículas com propriedades morfológicas e químicas diferenciadas. A fração do fundo contém as partículas mais uniformes, que formam cristais coloidais e filmes macrocristalinos opalescentes. Três características principais dos filmes de partículas foram analisadas: (i) a heterogeneidade e segregação das partículas nos filmes; (ii) a distribuição de solutos do soro do látex sobre o substrato; e (iii) a anisotropia dos agregados bidimensionais de partículas e sua influência sobre a distribuição dos solutos do soro do látex. Foram usadas as seguintes técnicas de microscopia de varredura de sonda (SPM): microscopia de força atômica de não-contato (AFM), microscopia de varredura de potencial elétrico (SEPM) e microscopia ótica de varredura em campo próximo (SNOM). Foram também usadas técnicas de microscopia eletrônica (EM) de transmissão (TEM), com aquisição de imagens espectroscópicas eletrônicas (ESI), e de varredura (SEM), com aquisição de imagens de elétrons secundários (SEI) e retroespalhados (BEI), e ainda de microscopia ótica de varredura confocal (SCM). A interação dos elétrons com as partículas do PS-AAM depositadas sobre mica foi modelada matematicamente para possibilitar a interpretação das imagens de BEI. Os principais resultados obtidos são os seguintes: (i) há diferentes tipos de partículas na fração do fundo do látex, que formam domínios de partículas distinguíveis dentro dos filmes; (ii) o crescimento dos agregados de partículas de uma sub-população é limitado pela agregação de partículas de outra sub-população; (iii) os solutos do soro do látex depositam-se sobre as partículas e o substrato, formando uma camada fina e uniforme de solutos ao redor dos agregados; (iv) os dipolos das partículas se orientam sobre o substrato anisotrópico de mica e essa orientação também influencia a deposição dos solutos do soro do látex ao redor das partículas, de maneira que tanto os agregados bidimensionais de partículas em submonocamadas quanto os depósitos de solutos são anisotrópicos.Abstract: This thesis presents the effects of latex particle microchemistry on the formation of particle films and monolayers of poly(styrene-co-acrylamide) (PS-AAM). The latex was fractionated by sedimentation under gravity yielding three particle fractions with differentiated morphological and chemical properties. The lower fraction contains the more uniform particles, which form colloidal crystals and opalescent macrocystaline films. Three main particle film features were analyzed: (i) the particle heterogeneity and segregation within the films; (ii) the latex serum solutes distribution on the film substrate; and (iii) the 2-D particle aggregates anisotropy and its influence on the serum solutes distribution. The following scanning probe microscopy (SPM) techniques were used: non-contact atomic force microscopy (AFM), scanning electric potential microscopy (SEPM) and scanning near-field optical microscopy (SNOM). Electron microscopy (EM) techniques were also used: transmission electron microscopy (TEM), with the acquisition of electron spectroscopic images (ESI), and scanning electron microscopy (SEM), with the acquisition of secondary electron images (SEI) and backscattered electron images (BEI). Scanning confocal optical microscopy (SCM) was also used. The electron interactions with PS-AAM particles deposited on mica were mathematically modeled to allow BEI image interpretation. The main results obtained are the following: (i) there are different particle types in the latex lower fraction and these cluster within the films, forming distinguishable particle domains; (ii) the growth of aggregates formed by one particle sub-population is limited by the aggregation of particles from another sub-population; (iii) latex serum solutes are deposited on the particles and substrate, forming a thin uniform solute layer surrounding the aggregates; (iv) particle dipoles orient themselves on the anisotropic mica substrate and this orientation also influences the deposition of serum solutes around the particles, in such a way that both the 2-D particle sub-monolayers and the solute deposits surrounding particle aggregates are anisotropic

Artificial Neural Network to Predict Structure-based Protein-protein Free Energy of Binding from Rosetta-calculated Properties

The prediction of the free energy (ΔG) of binding for protein-protein complexes is of general scientific interest that allows a variety of applications in the fields of molecular and chemical biology, material sciences, and biotechnology. Despite its centrality in understanding protein association phenomena and protein engineering, the ΔG of binding is a daunting quantity to be obtained theoretically. In this work, we devise a novel Artificial Neural Network model to predict the ΔG of binding for a given three-dimensional structure of a protein-protein complex with Rosetta-calculated properties. Our model presents a root-mean-square error of 1.667 kcal/mol outperforming available state-of-art tools. Validation of the model for a variety of protein-protein complexes is showcased

On the formation and accessibility of gold nanoparticles confined in SBA-15 mesoporous molecular sieve

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Mesoporous molecular sieves containing metal nanoparticles inside their pores have been lately studied as promising oxidation catalysts. Articles usually claim that confined particles are less prone to sintering and metal leaching. Furthermore, the pores limit nanoparticle growth during the process of preparation of the catalyst. In this work, we addressed some questions that are still to be answered, such as: how are the metal nanoparticles formed within the pores? Are these particles accessible to the organic molecules in catalytic reactions? For this purpose, SBA-15 samples containing Au nanoparticles were prepared and characterized. FTIR, TG/MS, XRD and XPS gave some insights on the formation of Au nanoparticles, while N-2 adsorption and SAXS were useful to address the accessibility question. It was observed that Au-SBA-15, in spite of having a pore size distribution similar of that of SBA-15, has a lower pore volume and half of the surface area. SAXS experimental data was interpreted with the aid of a theoretical model, and it was possible to demonstrate that the presence of metal induced changes on the lattice parameter and pore dimensions of SBA-15. The results strongly indicate that the pores were filled. TEM images reveal the presence of very small Au nanoparticles inside the pores of the material, and also larger particles on its external walls. Au-SBA-15 is thus a material that is very dissimilar from its precursor, pure-silica SBA-15, and so its adsorption properties must be carefully evaluated. (c) 2015 Elsevier Inc. All rights reserved.Mesoporous molecular sieves containing metal nanoparticles inside their pores have been lately studied as promising oxidation catalysts. Articles usually claim that confined particles are less prone to sintering and metal leaching. Furthermore, the pores2108693Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2011/12521-0, 2013/11298-0

Restructuring of Gold‐Palladium Alloyed Nanoparticles: A Step towards More Active Catalysts for Oxidation of Alcohols

International audienc

Interplay between near-field properties and au nanorod cluster structure: extending hot spots for surface-enhanced raman scattering

Materials science has observed a continuous increase in the use of metal nanoparticles in a wide range of studies, from fundamental physics to technological applications such as photocatalysis and optical communication devices. This broad scope has the same fundamental origin, the localized surface plasmons, whose excitation leads to strong light confinement, especially in the vicinity of closely spaced nanoparticles, the hot spots. The field amplification may be used to amplify the Raman scattering of adsorbed molecules, which is known as surface-enhanced Raman scattering (SERS). A crucial and limiting characteristic of SERS hot spots is their very localized nature. that influences the SERS intensity reproducibility as well as the probabilities of observation of single-molecule SERS signals. In this paper we discuss the correlation between SERS performance and gold nanorod cluster structures using transmission electron microscopy, SERS spectra and numerical simulations. The experimental data showed interesting behavior for the combination of end-to-end and side-by-side interactions, revealing the possibility of creating strong hot spots with a more extended spatial distribution. The results give insights into the development of high-performance SERS substrates301226242633CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP302792/2015-5; 408985/2016-0sem informação2011/17923-9; 2016/21070-

Interplay between near-field properties and Au nanorod cluster structure : extending hot spots for surface-enhanced raman scattering

Materials science has observed a continuous increase in the use of metal nanoparticles in a wide range of studies, from fundamental physics to technological applications such as photocatalysis and optical communication devices. This broad scope has the same fundamental origin, the localized surface plasmons, whose excitation leads to strong light confinement, especially in the vicinity of closely spaced nanoparticles, the hot spots. The field amplification may be used to amplify the Raman scattering of adsorbed molecules, which is known as surface-enhanced Raman scattering (SERS). A crucial and limiting characteristic of SERS hot spots is their very localized nature, that influences the SERS intensity reproducibility as well as the probabilities of observation of single-molecule SERS signals. In this paper we discuss the correlation between SERS performance and gold nanorod cluster structures using transmission electron microscopy, SERS spectra and numerical simulations. The experimental data showed interesting behavior for the combination of end-to-end and side-by-side interactions, revealing the possibility of creating strong hot spots with a more extended spatial distribution. The results give insights into the development of high‑performance SERS substrates

Catalytic abatement of CO over highly stable Pt supported on Ta2O5 nanotubes

The development of active and stable catalysts has emerged as an important strategy in the catalytic abatement of CO. This article reports the use of the novel Pt-based catalyst supported on crystalline Ta2O5 nanotubes prepared by sputtering and anodization methods in CO oxidation reaction. Crystalline and amorphous Ta2O5 NTs and Pt modified sample were found active in low temperature CO oxidation. Results showed that active and highly stable Pt/Ta2O5 NTs catalyst could be a promising system for CO removal from gas exhaust.Fil: Gonçalves, Renato V.. Universidade de Sao Paulo; BrasilFil: Wojcieszak, Robert. Universidade de Sao Paulo; BrasilFil: Uberman, Paula Marina. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Eberhardt, Dario. Universidade Federal do Rio Grande do Sul; BrasilFil: Teixeira Neto, Erico. Universidade de Sao Paulo; BrasilFil: Teixeira, Sergio Ribeiro. Universidade Federal do Rio Grande do Sul; BrasilFil: Rossi, Liane M.. Universidade de Sao Paulo; Brasi