排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
Karolien Verhaegen Leonardo Meeus Ronnie Belmans 《Renewable & Sustainable Energy Reviews》2009,13(1):208-215
In Europe, a common framework for renewable energy sources (RES) is aspired. Tradable green certificates (TGCs) are a market-based cost-efficient means to stimulate electricity production from RES. Since TGCs are the most widespread support scheme in Europe together with feed-in tariffs, chances are that a common European framework could well be based on TGCs. However, while integrating currently existing different national TGC systems, any remaining differences should be carefully considered. Just how difficult the creation of an international TGC market would be is illustrated in this paper by the case of Belgium, where no less than 4 different TGC systems exist nowadays. The example of Belgium illustrates that harmonizing different TGC systems is easier said than done and represents a serious challenge. This clearly illustrates that a single European support scheme for RES, however desirable, is still far in the future. 相似文献
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Marta Martinez-Garcia Winnie Dejonghe Lieve Cauwenberghs Miranda Maesen Karolien Vanbroekhoven Yamini Satyawali 《European Journal of Lipid Science and Technology》2021,123(2):2000225
Glucose- and xylose laurate esters are enzymatically synthesized using equimolar substrate concentrations in 2-methyl-2-butanol, comparing free lauric acid with methyl- and vinyl-laurate as acyl donors. All reactions result in ≥70% acyl donor conversions after 72 h but the activated donors are also partially hydrolyzed to lauric acid, highlighting the difficulty in controlling water presence in this particular reaction system. The esterification of xylose generates a complex product profile, with several regioisomers of monoesters and diesters. The esterification of glucose is quite selective, forming mainly the 6-O monoester (≥96%) with a small presence of two diester isomers (4%). Increasing substrate concentration up to 800 millimoles kg−1 results in lower conversion values (down to 58%) but shows that the reaction proceeds successfully even in the presence of high amounts of insoluble glucose. However, the reaction is less selective and the proportion of diester increases, becoming up to 46% (molar fraction) of the final product. Solvent recovery after esterification can be achieved by organic solvent nanofiltration through a polymeric membrane able to retain ≥80% of all reaction substrates and products. Practical Applications: The use of high substrate concentrations during the enzymatic synthesis of sugar ester biosurfactants leads to product titers that are more industrially appealing, without the need to find a solvent that can solubilize all initial substrate. The sustainability of the enzymatic conversion at mild temperatures can be enhanced by recycling of the reaction solvent through organic solvent nanofiltration, an energy efficient alternative to other traditional methods like distillation. 相似文献
3.
Karolien H. Kokke Judith A. Morris John G. Lawrenson 《Contact lens & anterior eye》2008,31(3):141-146
PURPOSE: Symptoms of dry eye are commonly reported in contact lens wearers and are a frequent cause of non-tolerance. The purpose of the present study is to evaluate the effects of oral treatment with particular omega-6 fatty acids in the form of evening primrose oil (EPO) on subjective symptoms, ocular surface signs and tear film characteristic in patients with contact lens associated dry eye. METHODS: The study design was randomised, double-masked and placebo controlled. 76 female soft contact lens wearers were treated for 6 months with either EPO or placebo (olive oil). Subjects underwent three examinations (baseline, 3 and 6 months). At each examination subjects were given a questionnaire relating to lens comfort and dry eye symptoms and underwent a series of tests of tear film characteristics (tear meniscus height, break-up time), meibomian gland function (lipid layer thickness and quality) and ocular surface parameters (hyperaemia and staining). RESULTS: The EPO group showed a significant improvement in the specific symptom of 'dryness' at 3 and 6 months (p<0.01) and also a significant improvement in overall lens comfort at 6 months (p<0.01). Tear meniscus height was increased in the EPO group at 6 months relative to baseline (p<0.01), although all other objective signs were unchanged. CONCLUSION: This study provides evidence for a beneficial effect of particular orally administered omega-6 fatty acids in alleviating dry eye symptoms and improving overall lens comfort in patients suffering from contact lens associated dry eye. 相似文献
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Cédric Rolin Karolien Vasseur Björn Niesen Myriam Willegems Robert Müller Sören Steudel Jan Genoe Paul Heremans 《Advanced functional materials》2012,22(23):5050-5059
Compared to traditional vacuum evaporation techniques for small organic molecules, organic vapor phase deposition (OVPD) possesses a extra processing parameter: the pressure of process gas Pch. Here, the influence of large Pch variations (from 0.1 mbar to atmospheric pressure) on pentacene thin film growth is explored. OVPD operation at higher Pch is characterized by lower carrier gas velocities and lower organic diffusivities. These result in an invariance of the material utilization efficiency over the entire pressure span and in an advantageous equilibrium evaporation regime in the source. An increase in Pch yields rough pentacene layers. Classical nucleation theory is applied to demonstrate how the pressure rise triggers homogeneous nucleation in the gas phase, causing the observed roughening. The use of lower deposition rates, higher dilution flow rates, and higher substrate temperatures result in the suppression of gas phase nucleation and the growth of smooth pentacene films at atmospheric pressure. Using these optimized conditions, state‐of‐the‐art pentacene thin film transistors with saturation mobilities above 0.9 cm2/Vs are reproducibly fabricated. p‐Type circuits are also made and a 19‐stage ring oscillator with a stage delay of 51 μs at a supply voltage of 15 V is demonstrated. 相似文献
6.
Diffusion of adhesion promoting and crosslinking additives in an uncured silicone sealant 总被引:2,自引:0,他引:2
A method has been devised for measuring the diffusion coefficient D of additives that act as adhesion promoters and crosslinking agents in uncured silicone sealants. This has been used to measure D for tetra-t-butyltitanate (TBT) and isobutyltrimethoxysilane (BTMS) in a sealant at 25°C. The value of D for TBT was found to be constant but that for BTMS decreased with the duration of the experiment, possibly due to the interaction of the silane with the silica particles. 相似文献
7.
The wearable revolution is already present in society through numerous gadgets. However, the contest remains in fully deployable wearable (bio)chemical sensing. Its use is constrained by the energy consumption which is provided by miniaturized batteries, limiting the autonomy of the device. Hence, the combination of materials and engineering efforts to develop sustainable energy management is paramount in the next generation of wearable self-powered electrochemical devices (WeSPEDs). In this direction, this review highlights for the first time the incorporation of innovative energy harvesting technologies with top-notch wearable self-powered sensors and low-powered electrochemical sensors toward battery-free and self-sustainable devices for health and wellbeing management. First, current elements such as wearable designs, electrochemical sensors, energy harvesters and storage, and user interfaces that conform WeSPEDs are depicted. Importantly, the bottlenecks in the development of WeSPEDs from an analytical perspective, product side, and power needs are carefully addressed. Subsequently, energy harvesting opportunities to power wearable electrochemical sensors are discussed. Finally, key findings that will enable the next generation of wearable devices are proposed. Overall, this review aims to bring new strategies for an energy-balanced deployment of WeSPEDs for successful monitoring of (bio)chemical parameters of the body toward personalized, predictive, and importantly, preventive healthcare. 相似文献
8.
Brahim Zarouali Karolien Poels Michel Walrave Koen Ponnet 《Behaviour & Information Technology》2018,37(5):502-516
This article examines how peer communication among adolescents (14–16 years) affects the evaluation of social advertising (i.e. targeted ad that adopts the social proof heuristic by using an individual’s social ties as endorsers for a brand) on social networking sites (SNSs). More precisely, the focus lies on how engaging in online peer chatting on these social platforms alters persuasion knowledge and attitude towards the ad. In order to test this, two between-subjects experiments were conducted in which adolescents chatted with peers on a mock SNS that contained a social ad. In Experiment 1, results reveal that a social ad generates a more positive attitude among adolescents when they have engaged in online peer communication, and at the same time, triggers less persuasion knowledge. In Experiment 2, the depth of the relationship between the chatters (tie strength) plays a significant moderating role as peer communication with strong ties yields greater effects, compared to communication with weak ties. These findings reveal important social influence dynamics that may alter the elaboration of persuasive communication, leading to valuable theoretical and practical implications. 相似文献
9.
The numerical resolution of the Vlasov equation provides complementary information with respect to analytical studies and forms an important research tool in domains such as plasma physics. The study of mean-field models for systems with long-range interactions is another field in which the Vlasov equation plays an important role. We present the vmf90 program that performs numerical simulations of the Vlasov equation for this class of mean-field models with the semi-Lagrangian method. 相似文献
10.
An aqueous sodium dodecanoate solution has been used for the formation of a protective coating for lead. Three deposition methods have been compared: immobilization using cyclic voltammetry, immersion and amperometry. Apart from this, we tested a reduction pretreatment of the lead surface (−1.5 V during 600 s) in order to obtain a more reproducible coating, resulting in a better corrosion protection behavior. The corrosion inhibition properties were examined using potentiodynamic polarization curves and electrochemical impedance measurements in a standard corrosive environment. 相似文献