Search results for "Chemical engineering"
showing 10 items of 5892 documents
New Insights into Segmental Packing, Chain Dynamics and Thermomechanical Performance of Aliphatic Polyurea Composites: Comparison between Silica Oxid…
2021
Polyurea (PU) is intrinsically reinforced by its microphase-separated morphology, giving its excellent mechanical properties. In this study, it is shown how a high-index PU formulation applies easy diffusion of hard segments into the soft phase of the PU matrix and tune its chain mobility. Moreover, the interaction of micro (>100 nm), nano (<100 nm) fillers with the microdomains and their thermomechanical properties are unraveled. Herein, nanosilica oxide (NS) and micro titanium (III) oxide (Ti2O3) are incorporated at low loadings into a solvent-free two-component aliphatic PU via insitu polymerization. While NS achieves an interfacial interaction with urea groups and forms a tight ha…
Unlocking mixed oxides with unprecedented stoichiometries from heterometallic metalorganic frameworks for the catalytic hydrogenation of CO 2
2021
[EN] Their complex surface chemistry and high oxygen lattice mobilities place mixed-metal oxides among the most important families of materials. Modulation of stoichiometry in mixed-metal oxides has been shown to be a very powerful tool for tuning optical and catalytic properties. However, accessing different stoichiometries is not always synthetically possible. Here, we show that the thermal decomposition of the recently reported metal-organic framework MUV-101(Fe, Ti) results in the formation of carbon-supported titanomaghemite nanoparticles with an unprecedented Fe/Ti ratio close to 2, not achievable by soft-chemistry routes. The resulting titanomaghemite phase displays outstanding catal…
Parametric sensitivity of a CFD model concerning the hydrodynamics of trickle-bed reactor (TBR)
2016
Abstract The aim of the present study was to investigate the sensitivity of a multiphase Eulerian CFD model with respect to relations defining drag forces between phases. The mean relative error as well as standard deviation of experimental and computed values of pressure gradient and average liquid holdup were used as validation criteria of the model. Comparative basis for simulations was our own data-base obtained in experiments carried out in a TBR operating at a co-current downward gas and liquid flow. Estimated errors showed that the classical equations of Attou et al. (1999) defining the friction factors Fjk approximate experimental values of hydrodynamic parameters with the best agre…
Ecology of Vastedda della valle del Belìce cheeses: A review and recent findings to stabilize the traditional production
2018
The increasing request for classic foods has led to a higher demand for cheeses enjoying a “recognition of quality” status. This phenomenon has also affected Sicilian dairy products, in particular protected designation of origin (PDO) “Vastedda della valle del Belìce” (VdB), a cheese traditionally available only during the summer season, but requested year round. The variations of the microbial populations of raw milk among the seasons influence the microbiological quality of the cheeses produced. This review article reports the historical importance of cheeses and the traditional equipment used for dairy productions in Sicily with a specific focus on VdB. The microbial ecology of this chee…
Nanofilm Low Cost Oxygen Sensors
2009
Abstract The resitivity change of ultra thin metals under air exposure is used for vacuum or inert gas packaging control. In order to reach low cost, single use applications, few nm thin Aluminum layers were deposited on PET substrates and combined with wireless electronic readout circuitry. The sensor respose is characterized by resistance changes and explained in terms of multiphase diffusion mechanisms which are very sensitive to technological parameters.
Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts
2019
A versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc-gallium oxynitrides and zinc-gallium-indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well-defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2 g-1 ). X-ray diffraction studies show that the final material is not a…
IVyF: Validez de un Instrumento de Medida de las Fortalezas del Carácter de la Clasificación de Peterson y Seligman (2004)
2015
El IVyF (Strength of Character Inventory, en inglés) es un instrumento de medición de las 24 fortalezas del carácter de la clasificación de Peterson y Seligman (2004). A diferencia de otros cuestionarios homólogos para medir las fortalezas de esa clasificación que están compuestos por decenas de ítems, el IVyF es un instrumento de medición de 24 ítems. Este estudio se enfocó en la validez del IVyF. En primer lugar, el IVyF estuvo asociado a medidas de variables conceptualmente relevantes como satisfacción con la vida, los factores de personalidad del modelo de los Cinco Grandes, y deseabilidad social. En segundo lugar, se hallaron asociaciones con tamaños del efecto mayores a mediano entre …
Physico-Chemical Properties and Use of Waste Biomass-Derived Activated Carbons
2017
Activated carbons are widely used in different industrial processes for example as adsorbents or as support materials. Advantageously these carbons can be prepared from residual or waste biomass materials. Different raw material type and activation procedure plays an important role in the physico-chemical characteristics of activated carbon e.g. surface area, porosity and pore distribution. In this study, activated carbon has been prepared from lignocellulosic waste materials (e.g. saw dust, lignin residue) and characterized by a number of methods. Further, adsorption properties of carbons were evaluated. Adsorption capacity of dyes and metals was high (methylene blue dye 86 % and zinc meta…