A new sulphonic acid functionalized periodic mesoporous organosilica as a suitable catalyst

A new solid acid catalyst is developed by the direct sulphonation of the ethene bond of a pure trans ethene bridged Periodic Mesoporous Organosilica. The catalytic activity of this mesoporous material is evaluated in an esterification reaction and compared with ptoluenesulphonic acid. The sulphonated ethene PMO can compete with a homogeneous catalyst and maintains its porosity

Isomeric olefinic periodic mesoporous organosilicas: an emerging class of versatile nanomaterials

Porous materials appear widely in nature and are the subject of intense study in many research areas owing to their unique properties. Their ability to interact with atoms, ions and molecules has lead to their wide spread applicability in sorption, catalysis, chromatography, ion exchange, micro-electronics, environmental technology, controlled drug release, . . . In the field of porous materials, scientists aim to control the size, shape, uniformity and periodicity of porous space and the atoms and molecules that define it. By controlling and fine-tuning these properties, materials can be engineered to meet the desired function and behaviour in a particular application. The presented research work describes the development, characterization and catalytic application of diastereoisomeric olefinic periodic mesoporous organosilicas (PMOs). PMOs are very unique in their compositional structure. The organic groups are covalently bonded within the siliceous network and hence are an intrinsic constituent of the mesoporous framework. The high loading and uniform distribution of organic groups in the pore walls of these open porous structures is a distinctive feature which allows for the easy tailoring of the PMO properties. From this perspective olefinic PMOs are very appealing, as they offer plenty of opportunities for surface modification based on olefin chemistry. To date, only limited research has been done on these very promising type of organic-inorganic hybrid materials and their potential in various applications has not been explored yet. The main goal of this research work has been the development of a novel class of versatile olefinic PMOs, which consist of diastereoisomerically configured organic bridges in their pore walls. The aim was to investigate new synthesis strategies which enable the synthesis of highly stable hybrid materials with controllable chemical and physical properties. By means of a detailed analysis of the developed PMO materials, an effort has also been made to understand the complex mechanisms involved in the supramolecular self-assembly process of ethenylene-bridged PMOs. Furthermore, with the intent of expanding the scope of olefinic PMOs, both the synthesis of new materials and the application thereof in catalysis has been studied

Cost-benefit analysis of abatement measures for nutrient emission from agriculture

In intensive animal husbandry areas surface water N and P concentrations often remain too high. The Water Framework Directive calls for additional nutrient emission abatement measures. Therefore, costs and benefits for possible agricultural measures in Flanders were first analysed in terms of soil balance surplus. Finally, abatement measures for agriculture, households and industry were set off against each other and ranked according to their cost-efficiency by the Environmental Costing Model. Increased dairy cattle efficiency, winter cover crops and increased pig feed efficiency turn out very cost efficient. Other agricultural measures are less cost efficient than for instance collective treatment for households and industry.nitrogen and phosphorus abatement, surface water, cost efficiency, Environmental Economics and Policy, Livestock Production/Industries,

Isomeric periodic mesoporous organosilicas with controllable properties

The synthesis procedure for isomeric periodic mesoporous organosilicas with E-configured ethenylene bridges was investigated using the homemade pure E-isomer of 1,2-bis(triethoxysilyl)ethene. The pH, aging temperature and the presence of cosolvents played a key role in obtaining well-ordered mesoporous materials with controllable properties and morphologies. By fine-tuning the reaction mixture acidity, PMOs with high surface areas and pore volumes could be attained. By selecting various alcohols as cosolvents and optimizing the alcohol concentration, PMOs with crystal-like disc shaped, fibrous and spherical particle morphologies were obtained. The synthesis temperature of these ethenylene-bridged PMOs influences the pore size, structure, connectivity and volume

Metacognition and motivation as predictors for mathematics performance of Belgian elementary school children

In this paper, we investigate the role of metacognitive postdiction skills, intrinsic motivation and prior proficiency in mathematics as Propensity factors within the opportunity-propensity (O-P) model of learning. We tested Belgian children from Grade 1 till 6 in January and June. The study revealed overlapping yet different predictors for mathematical accuracy and fluency, which led us to the practical recommendation for teachers to pay attention to both aspects of mathematics. The metacognitive postdiction skills of children were related to accuracy in mathematics during the whole elementary school period. In addition, we observed that children evaluated their own performance as worse when they were slower in Grades 3 and 4. Intrinsic motivation was related to accuracy but not to fluency in Grade 3. Especially prior mathematical accuracy mattered as a propensity factor. More than half of the variance in accuracy and less than one-fifth of the variance in fluency in January predicted the performances of children for mathematics in June, a finding that highlights the importance of longitudinal designs including students' prior mathematical accuracy' as well. Finally, we observed that poor mathematics performers are less intrinsically motivated, and less metacognitively accurate. Moreover, they overestimate their performances more often than well-performing peers in all grades, stressing the importance of paying attention to these aspects in mathematics education

How I manage drainage insufficiency on extracorporeal membrane oxygenation

No abstract was provided by the editors of this work

Pressure and Flow Properties of Cannulae for Extracorporeal Membrane Oxygenation I: Return (Arterial) Cannulae

Adequate extracorporeal membrane oxygenation support in the adult requires cannulae permitting blood flows up to 6-8 L/minute. In accordance with Poiseuille's law, flow is proportional to the fourth power of cannula inner diameter and inversely proportional to its length. Poiseuille's law can be applied to obtain the pressure drop of an incompressible, Newtonian fluid (such as water) flowing in a cylindrical tube. However, as blood is a pseudoplastic non-Newtonian fluid, the validity of Poiseuille's law is questionable for prediction of cannula properties in clinical practice. Pressure-flow charts with non-Newtonian fluids, such as blood, are typically not provided by the manufacturers. A standardized laboratory test of return (arterial) cannulae for extracorporeal membrane oxygenation was performed. The aim was to determine pressure-flow data with human whole blood in addition to manufacturers' water tests to facilitate an appropriate choice of cannula for the desired flow range. In total, 14 cannulae from three manufacturers were tested. Data concerning design, characteristics, and performance were graphically presented for each tested cannula. Measured blood flows were in most cases 3-21% lower than those provided by manufacturers. This was most pronounced in the narrow cannulae (15-17 Fr) where the reduction ranged from 27% to 40% at low flows and 5-15% in the upper flow range. These differences were less apparent with increasing cannula diameter. There was a marked disparity between manufacturers. Based on the measured results, testing of cannulae including whole blood flows in a standardized bench test would be recommended.info:eu-repo/semantics/publishedVersio