220,488 research outputs found
On the Desirability of Coordinated Supply-side Intervention: Does a Monetary Union Matter?
No full textThis paper examines the desirability of coordinated supply-side intervention within a monetary union, given the constraints on monetary and fiscal policy. The author considers an economic framework featuring independent monetary policy. In general, coordinated intervention is most useful against shocks that require distinct policy responses in each separate economy.monetary union, supply-side policies, policy coordination
Nanoscale imaging of buried topological defects with quantitative X-ray magnetic microscopy
No full textSpanish MINECO under grant FIS2013- 45469. A. Hierro-Rodriguez acknowledges support from FCT of Portugal (Grant SFRH/BPD/90471/2012). C. Blanco-Roldán thanks support from CSIC JAE Predoc Progra
Otro título: Ciudad:
No full textTítulo tomado de la cubiertaDirector : Víctor de la Serna; Redactor-jefe : Eduardo Blanco-AmorA partir de n. 18, 39 c
Fracionamento do óleo essencial de Patchouli [Pogostemon cablin (Blanco) Benth.] obtido por extração supercrítica
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Química.O fracionamento do óleo essencial de patchouli [Pogostemon cablin (Blanco) Benth.] extraído com dióxido de carbono supercrítico (CO2_SC) foi estudado. Este óleo essencial é muito usado pela indústria de cosméticos e perfumaria como excelente fixador de aromas. Adotando-se pressão e temperatura de trabalho em 100 bar e 32°C, respectivamente, foram estudados alguns parâmetros nunca antes averiguados para o patchouli. O trabalho se dividiu em quatro frentes de estudo: aumento de rendimento variando o tempo de extração e tempo estático; análise do tamanho ideal de partícula; épocas de colheita; composição química do óleo essencial. O tempo estático combinado com o tempo de coleta de amostras foi estudado com o objetivo de aumentar o rendimento do processo, resultando em um tempo ideal de 20 minutos de tempo estático e de tempo para coleta de amostras. Três tamanhos "médios" de partículas foram estudados à duas diferentes vazões de solvente. O tamanho de partícula ideal para a extração supercrítica do óleo essencial de patchouli foi de 0,346 mm à vazão de 1,2 L/min de CO2. Lotes de folhas de patchouli colhidas em diferentes épocas do ano foram usados para extração de seu óleo essencial. A época do ano nas quais se obtiveram melhores rendimentos foi no inverno. A composição química do óleo essencial de patchouli foi estudada com a intenção de saber a que tempo de processo os principais compostos de interesse (patchoulol e a-bulneseno) são extraídos. As amostras de óleo essencial analisadas forneceram resultados suficientes para se traçar o perfil de concentração destes compostos com o tempo de extração. Sabendo-se o tempo ideal de coleta de amostras, pode-se estabelecer um método de fracionamento para óleo essencial de patchouli. The fractionation of the essential oil of patchouli [Pogostemon cablin (Blanco) Benth.] extracted with supercritical carbon dioxide (CO2_SC) was studied. This oil is widely used by industries of cosmetics and fragrances. Bringing up of work pressure and temperature at 100 bar and 32 ° C, respectively, were studied some parameters never before investigated for the patchouli. The work was divided into four subjects of study: increasing yield varying the static period and the total time of extraction; analysis of the optimal particle size; harvest period; chemical composition of the essential oil. The static period combined with the time of collection of samples was studied with the objective of increasing the yield of the process, resulting in an ideal time of 20 minutes of static period and time for collection of samples. Three "averages" particles sizes were studied for two different flows of solvent. The ideal particle size for the supercritical extraction of essential oil of patchouli was 0.346 mm, at flow rate of 1.2 L / min of CO2. Lots of patchouli leaves harvested at different times of the year were used for extraction of its essential oil. The time of the year which it was obtained better yield is the winter. The chemical composition of the essential oil of patchouli was studied with the intention of knowing that process time the main compounds (patchoulol and a-bulnesene) are extracted. Samples of essential oil analyzed results provided sufficient to trace the profile of concentration of these compounds. Knowing the perfect time of collection of samples, can be possible to establish a method for the fractionation of patchouli essential oil
Design and Thermal and Spectroscopic Characterization of novel architecture’s POSS nanoparticles
No full textPolyhedral oligomeric silsesquioxanes (POSSs), with Si vertices interconnected by –O– linkages, form three-dimensional nanometer size cage structures with substituents attached to silicon atoms. These substituents may contain reactive groups, such as hydroxyl or isocyanate. A combination of a rigid inorganic nanocore with organic vertex groups makes POSS molecules useful hybrid building blocks that can be chemically incorporated in the polymer matrix by copolymerization, grafting or reactive blending, or physically mixed by solvent casting or polymer processing by using, for example, the extrusion technique [1]. The use of POSSs for making polymer composites has grown exponentially since the last few years of the 20th century. In comparison with the other most commonly used fillers, POSSs possess the advantage of being molecules. Thus, this allows us to combine their nano-sized cage structures, which have dimensions that are similar to those of most polymer segments and produce a particular and exclusive chemical composition. These characteristics linked with their hybrid (inorganic–organic) nature allow researchers to modify POSS according to particular needs or original ideas, before incorporating them into polymers [2].
Figure 1. Molecular structure of the prepared and investigated POSSs
In this context, our research group at the University of Catania, in collaboration with eminent researchers in the field, tested the stabilization of different polymers, synthetics or naturals, such as polyethersulfone (PES), ethylene propylene diene monomer (EPDM), polyethylene oxide (PEO), and chitosan by the incorporation of polyhedral oligomeric silsesquioxanes (POSS) molecules [3-6]. Represented in their most common form by the symbol T8 and having a diameter usually falling in the range of 1.5–3 nm, POSS molecules comprise a silicon and oxygen cage completed by organic groups that are covalently bonded with silicon atoms. Novel architectures of POSS with various organic groups were synthesized by using corner capping reaction in order to verify their polimeryzability in the presence of monomer. In this work, after a spectroscopic investigation aiming at verify that the obtained molecules have the structure for which they were designed, their thermal behavior in terms of resistance to thermal degradation were evaluated by means of thermogravimetric analysis (TGA). The obtained temperatures at 5% mass loss (T5%) were compared with each other and with those of the POSSs previously designed and studied by us.
Bibliography
[1] Lichtenhan, J.D., Pielichowski, K., Blanco, I. POSS-Based Polymers. Polymers 2019, 11, 1727
[2] Blanco, I. The Rediscovery of POSS: A Molecule Rather than a Filler. Polymers 2018, 10, 904.
[3] Cicala, G., Blanco, I., Latteri, A., Ognibene, G., Agatino Bottino, F., Fragalà, M.E. PES/POSS Soluble Veils as Advanced Modifiers for Multifunctional Fiber Reinforced Composites. Polymers 2017, 9, 281
[4] Zaharescu, T., Blanco, I., Bottino, F.A. Antioxidant activity assisted by modified particle surface in POSS/EPDM hybrids. Appl. Surf. Sci. 2020, 509, 144702
[5] Legnani, L.; Iannazzo, D.; Pistone, A.; Celesti, C.; Giofrè, S.; Romeo, R.; Di Pietro, A.; Visalli, G.; Fresta, M.; Bottino, P.; et al. Functionalized polyhedral oligosilsesquioxane (POSS) based composites for bone tissue engineering: Synthesis, computational and biological studies. RSC Adv. 2020, 10, 11325–11334
[6] Stipanelov Vrandečić, N., Erceg, M., Andričić, B., Blanco, I., Bottino, F.A. Characterization of poly(ethylene oxide) modified with different phenyl hepta isobutyl polyhedral oligomeric silsesquioxanes. J. Therm. Anal. Calorim. 2020, 142, 1863–187
APORTACIÓN A LA OBRA DEL ESCULTOR SEVILLANO JERÓNIMO ROLDÁN
No full textWe offer the biographical outline of Jerónimo Roldán (c.1701-c.1780), sevillian image-maker, who is famous Pedro Roldán's grandson. Also, a stylistic and iconographical research of his brief and know output is shored. Finally, we bring forward some documents and study of an early and unpublished work, now missing, which is three "jews" carved in 1730 for the Nuestra Señora del Valle Brotherhood, in Seville.Ofrecemos el perfil biográfico del imaginero sevillano Jerónimo Roldán (c.1701-c.1780), nieto del afamado Pedro Roldán, así como el análisis estilístico e iconográfico de su corta producción conocida. Finalmente, aportamos la documentación y estudio de una obra temprana e inédita, ya desaparecida; nos referimos a los tres "judíos" que esculpió en 1730 para la Hermandad de Nuestra Señora del Valle, de Sevilla
El rol de la respiración mitocondrial y la proteína CYT-C en el crecimiento y desarrollo vegetal
No full textFil: Roldán, Facundo. Instituto de Agrobiotecnología del Litoral; Argentina
- …
