Surface Science Meets Catalysis Research: Iron oxide films for in-situ model catalysis

An in-depth model catalysis study on a complex system is reviewed. Both unpromoted and potassium-promoted iron oxide model catalysts films of single crystalline quality are prepared and characterized in ultrahigh vacuum (UHV) using surface science methods. In order to bridge the pressure and material gap for the catalytic dehydrogenation of ethylbenzene to styrene in presence of steam, this reaction is studied at reactive gas pressures between 10-6 and 36 mbar. The samples are transferred under vacuum into an stagnation point micro-flow reactor where the reaction is studied, followed by post-reaction characterization in UHV. Clean hematite Fe2O3 is an excellent catalyst but deactivates quickly by reduction and by coking. Addition of H2O limits reduction to the oxidation state of magnetite Fe3O4 and counteracts coking. Both deactivation mechanisms can be avoided by addition of some O2 to the feed. Potassium has basically the same functions as O2. It does not seem to be involved in the catalytic dehydrogenation step but rather to block active sites if its concentration is high. Long-term deactivation occurs mainly by potassium removal in form of volatile KOH. Regeneration by “steaming” in pure H2O accelerates this process while ethylbenzene in the feed stabilizes potassium. This is ascribed to the formation of non-volatile K2CO3 which is an intermediate in potassium catalysed coke removal. The addition of O2 instead of K-promotion may be an alternative reaction route

Tunable magnetocaloric effect around room temperature by Fe doping in Mn0.98Cr(0.02-x)FexAs compound

In this work, we present an investigation of the magnetic and magnetocaloric properties of Mn0.98Cr(0.02-x)FexAs compounds with x = 0.002, 0.005 and 0.010. Our findings show that as Fe content increases the unit cell volume decreases, which indicates that Fe doping emulates the pressure effect on the crystalline structure. The transition temperature TC decreases as x increases and it can be set at approximate value of room temperature by changing the doping level. In addition, the magnetic entropy change ΔSM was determined using a discontinuous measurement protocol, and realistic values from the magnetocaloric effect presented by MnAs-type compounds under pressure (emulated pressure) could be obtained. The values of ΔSMMAX are very large, around −11 Jkg−1K−1 with ΔH = 15 kOe, which is higher than that observed for most compounds with TC around room temperature. However, ΔSM is confined to a narrow temperature range of 11 K. To overcome this drawback, the composition of a theoretical composite formed by our samples was calculated in order to obtain a table-shaped ΔSM curve. The simulated composite showed a high value of full width at half maximum δTFWHM of 33 K, which is much higher than that of single sample.Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro - FAPERJ E-26/110.393/2014, E-16/210.263/2014Coordenação de aperfeiçoamento de pessoal de nivel superior - CAPES 485200/2013-9Fundación de Apoyo a la Investigación del Estado de São Paulo - FAPESP 2012/03480-0Ministerio de Economía y Competitividad MAT2013-45165-

Free-energy analysis of the nonhysteretic first-order phase transition of Eu2In

Binary intermetallic Eu2In was recently reported to exhibit a giant anhysteretic magnetocaloric effect due to a first-order magnetic phase transition between paramagnetic and ferromagnetic states. Experimentally, the transition occurs with a small phase volume change, ΔV/V, of approximately 0.1% around TC of ca. 55 K. We represent magnetic and compute magnetocaloric properties of a Eu2In compound using a microscopic description based on a model Hamiltonian that takes into account magnetic exchange and magnetoelastic interactions. In the model the thermodynamic nature of the transition is conveniently represented by a single magnetoelastic interaction parameter. A good agreement between the theoretical results and earlier published experimental data confirms the effectiveness of our approach

Influence of chemical doping and hydrostatic pressure on the magnetic properties of Mn1-xFexAs magnetocaloric compounds

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOThis paper presents the results of an investigation of the magnetic and structural properties of Mn1-xFexAs compounds under hydrostatic pressure and chemical doping. The chemical doping was performed by using low Fe doping levels (x=0, 0.003, 0.006, 0.010, 0.015, and 0.018), which emulates the negative pressure effect on the crystal structure. The results of this approach were compared with the physical pressure effect (hydrostatic pressure from 0 to 2.2 kbar) on the Mn0.997Fe0.003As. Both approaches exhibit the same magnetic behaviors: the TC and saturation magnetization decrease as the pressure increases; for the highest pressure studied, an orthorhombic antiferromagnetic phase occurs below the critical temperature and coexists with the ferromagnetic hexagonal phase. The equivalence between hydrostatic pressure and chemical doping indicates that the Fe doping only causes structural deformation. In addition, we performed magnetic measurements at high temperature (up to 520 K) on the samples with x=0 and 0.003 in order to investigate the magnetic behavior above TC=310 K. These results, along with structural characterization, clearly show that between TC and Tt the system is a weak antiferromagnet with short-range order confined only in the ab plane. Finally, using the low- and high-temperature data, the magnetic phase diagrams of the compound under hydrostatic pressure and chemical doping were redrawn. © 2016 American Physical Society.This paper presents the results of an investigation of the magnetic and structural properties of Mn1-xFex As compounds under hydrostatic pressure and chemical doping. The chemical doping was performed by using low Fe doping levels (x = 0, 0.003, 0.006, 0.010, 0.015, and 0.018), which emulates the negative pressure effect on the crystal structure. The results of this approach were compared with the physical pressure effect (hydrostatic pressure from 0 to 2.2 kbar) on the Mn0.997Fe0.003As. Both approaches exhibit the same magnetic behaviors: the T-C and saturation magnetization decrease as the pressure increases, for the highest pressure studied, an orthorhombic antiferromagnetic phase occurs below the critical temperature and coexists with the ferromagnetic hexagonal phase. The equivalence between hydrostatic pressure and chemical doping indicates that the Fe doping only causes structural deformation. In addition, we performed magnetic measurements at high temperature (up to 520 K) on the samples with x = 0 and 0.003 in order to investigate the magnetic behavior above T-C = 310 K. These results, along with structural characterization, clearly show that between T-C and T-t the system is a weak antiferromagnet with short-range order confined only in the ab plane. Finally, using the low- and high-temperature data, the magnetic phase diagrams of the compound under hydrostatic pressure and chemical doping were redrawn.93519CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSem informaçãoSem informaçãoSem informaçãoSem informaçãoSem informaçãoThe authors would like to thank to CNPq, CAPES, FAPERJ, FAPEMIG, FAPESP, and PROPPI-UFF for financial support

Understanding the physical properties, toxicities and anti-microbial activities of choline-amino acid-based salts:Low-toxic variants of ionic liquids

International audienc

Set up of a methodology for participatory plant breeding in bread wheat in France

In Organic Agriculture, cultivation environments and agronomic practices are very diverse. This diversity can be handled with decentralized selection based on the knowledge of farmers and scientists. A collaborative work between associations from Réseau Semences Paysannes and the DEAP team from INRA du Moulon set up an innovative breeding approach on farm based on decentralization and participation of farmers. This approach makes it possible to (i) create new population varieties of bread wheat locally adapted (genetic innovation) (ii) set up an organizational scheme based on decentralization and co construction between actors (societal innovation) and (iii) develop experimental designs, create statistical and data management tools which stimulate these genetic and societal innovations

Growth Hormone Research Society perspective on the development of long-acting growth hormone preparations

Objective The Growth Hormone (GH) Research Society (GRS) convened a workshop to address important issues regarding trial design, efficacy, and safety of long-acting growth hormone preparations (LAGH). Participants A closed meeting of 55 international scientists with expertise in GH, including pediatric and adult endocrinologists, basic scientists, regulatory scientists, and participants from the pharmaceutical industry. Evidence Current literature was reviewed for gaps in knowledge. Expert opinion was used to suggest studies required to address potential safety and efficacy issues. Consensus process Following plenary presentations summarizing the literature, breakout groups discussed questions framed by the planning committee. Attendees reconvened after each breakout session to share group reports. A writing team compiled the breakout session reports into a draft document that was discussed and revised in an open forum on the concluding day. This was edited further and then circulated to attendees from academic institutions for review after the meeting. Participants from pharmaceutical companies did not participate in the planning, writing, or in the discussions and text revision on the final day of the workshop. Scientists from industry and regulatory agencies reviewed the manuscript to identify any factual errors. Conclusions LAGH compounds may represent an advance over daily GH injections because of increased convenience and differing phamacodynamic properties, providing the potential for improved adherence and outcomes. Better methods to assess adherence must be developed and validated. Long-term surveillance registries that include assessment of efficacy, cost-benefit, disease burden, quality of life, and safety are essential for understanding the impact of sustained exposure to LAGH preparations