Improvement of Catalytic Performance of Perovskites by Partial Substitution of Cations and Supporting on High Surface Area Materials

In this chapter, we present two relevant strategies to improve the activity and selectivity of perovskite-mixed oxides ABO3 in heterogeneous catalytic reactions such as the oxidation of hydrocarbons, soot combustion and CO selective oxidation, for which the surface sites and lattice oxygen species play important roles for the chemical transformations. Besides, we focus on synthesis of higher alcohols, partial oxidation of methane, oxidative reforming of diesel and dry reforming of methane for which the perovskite is a precursor that leads to a dispersed metal active phase over an oxide matrix. But which strategies are we talking about? First, the partial substitution of cations A and B by different elements, which change atomic distances, causes unit cell distortions, stabilizes multiple oxidation states or induces cationic or anionic vacancies within the lattice. And all these new features perturb the solid reactivity by changing the reaction mechanism on the catalyst surface. Thus, appropriate cations substitutions may lead to better catalysts. The second strategy comprises supporting the perovskite, which usually presents low surface area, on high surface area materials to maximize the exposed surface sites

BMP2 and TGF-β Cooperate Differently during Synovial-Derived Stem-Cell Chondrogenesis in a Dexamethasone-Dependent Manner

Recent studies highlighting mesenchymal stem cell (MSC) epigenetic memory suggest that a different differentiation medium may be required depending on the tissue of origin. As synovial-derived stem cells (SDSCs) attract interest we aimed to investigate the influence of TGF-β1, BMP-2 and dexamethasone on SDSC chondrogenesis in vitro. We demonstrate that dexamethasone-free medium led to enhanced chondrogenic differentiation at both the mRNA and matrix level. The greatest COL2A1/COL10A1 ratio was detected in cells exposed to a combination medium containing 10 ng/mL BMP-2 and 1 ng/mL TGF-β1 in the absence of dexamethasone, and this was reflected in the total amount of glycosaminoglycans produced. In summary, dexamethasone-free medium containing BMP-2 and TGF-β1 may be the most suitable when using SDSCs for cartilage tissue regeneration

Syngas Production Using Natural Gas from the Environmental Point of View

The search for clean and low-cost fuels as alternative for petroleum is a popular research focus in the energy field. The demand of natural gas as an energy source has increased steadily. The high H:C ratio and the absence of heteroatoms make natural gas an attractive feedstock for synthetic fuels and chemicals that can replace those that are typically petroleum-derived. The search for efficient routes to convert methane to other higher added-value products is a challenge for the scientific community. In addition, new fields of oil and gas contain associated CO2 (8–18%), and, in some specific fields, the associated gas encloses a higher CO2 content (79%). In this context, the tri-reforming process combines two of the most problematic greenhouse gases (CH4 and CO2) to generate syngas for the synthesis of clean liquid fuels and valuable chemicals. Developments in tri-reforming processes, which include the new catalysts, are presented in this chapter

Microkinetic modeling of the Water-Gas Shift reaction over cobalt catalysts supported on multi-walled carbon nanotubes

The development of microkinetic models allows gaining an understanding of fundamental catalyst surface phenomena in terms of elementary reaction steps without a priori defining a rate-determining step, yielding more meaningful and physically reliable reaction rates. This work aimed at developing such a microkinetic model that accurately describes the Water-Gas Shift (WGS) reaction, i.e., one of the major routes for hydrogen production, over cobalt (Co) catalysts supported on multi-walled carbon nanotubes (MWCNTs). Co is known for its sulfur-tolerance and the functionalized MWCNT support has exceptional conductivity properties and defects that facilitate electron transfer on its surface. The model was formulated based on a well-known mechanism for the WGS reaction involving the highly reactive carboxyl (COOH*) intermediate. The kinetic parameters were computed by a combination of calculation via theoretical prediction models (such as the Collision and Transition-State theory) and via regression to the experimental data. The derived system of differential-algebraic equations was solved using the DDAPLUS package available in the Athena VISUAL Studio. The developed model was capable of simulating the experimental data (R² = 0.96), presenting statistically significant kinetic parameters. Furthermore, some of the catalyst descriptors in the model have been related to the catalyst properties as determined by characterization techniques, such as the specific surface area (SP = 22,000 m²/kgcat) and the density of active sites (σ = 0.012 molAct.Surf./kgcat). The modelling and characterization efforts allowed identifying the COOH* formation reaction (CO* + OH* → COOH* + *) as the surface reaction with the highest activation energy. Optimal catalyst performance, resulting in a CO conversion exceeding 85%, was simulated at elevated temperatures (350–450 °C) and space times (70–80 kg·s/mol), in agreement with the experimental observations

Factores que inciden en el financiamiento de los estudios Universitarios en Chile

El artículo da cuenta de los principales factores que inciden en el financiamiento de los estudios universitarios en Chile, exponiéndose los fundamentos y relaciones de un modelo para estimar el volumen de los recursos comprometidos y sus opciones de provisión. En las últimas dos década el mercado universitario ha duplicando su masa de estudiantes fenómeno que continuará por esta senda, implicando serias presiones sobre el financiamiento público, en un sistema que ya tiene una elevada participación financiera privada. El modelo que se propone apunta a proveer un enfoque sistémico para abordar la problemática planteada

Application of integrated transcriptomic, proteomic and metabolomic profiling for the delineation of mechanisms of drug induced cell stress

International audience; High content omic techniques in combination with stable human in vitro cell culture systems have the potential to improve on current pre-clinical safety regimes by providing detailed mechanistic information of altered cellular processes. Here we investigated the added benefit of integrating transcriptomics, proteomics and metabolomics together with pharmacokinetics for drug testing regimes. Cultured human renal epithelial cells (RPTEC/TERT1) were exposed to the nephrotoxin Cyclosporine A (CsA) at therapeutic and supratherapeutic concentrations for 14 days. CsA was quantified in supernatants and cellular lysates by LC-MS/MS for kinetic modeling. There was a rapid cellular uptake and accumulation of CsA, with a non-linear relationship between intracellular and applied concentrations. CsA at 15 µM induced mitochondrial disturbances and activation of the Nrf2-oxidative-damage and the unfolded protein-response pathways. All three omic streams provided complementary information, especially pertaining to Nrf2 and ATF4 activation. No stress induction was detected with 5 µM CsA; however, both concentrations resulted in a maximal secretion of cyclophilin B. The study demonstrates for the first time that CsA-induced stress is not directly linked to its primary pharmacology. In addition we demonstrate the power of integrated omics for the elucidation of signaling cascades brought about by compound induced cell stress

Processo para a produção de hidrocarbonetos clorados

Em 06/07/2016: Anuidade de patente de invenção do 11º ao 15º ano no prazo ordinárioConcedidaA presente invenção refere-se a um processo conduzido em baixas temperaturas para a produção de hidrocarbonetos clorados com elevada seletividade e conversão. Mais especificamente, a presente invenção consiste em um processo particularmente adequado ao aproveitamento de uma corrente originária do acoplamento oxidativo do metano, para obtenção de cloreto de vinila e/ou 1,2-dicloroetano