Modification of inorganic surface with 1-alkenes and 1-alkynes

Surface modification is important because it allows the tuning of surface properties, thereby enabling new applications of a material. It can change physical properties such as wettability and friction, but can also introduce chemical functionalities and binding specificity. Several techniques are available to modify the surface. Of these, organic monolayers have the advantages that they are easily tunable, fairly stable, and do not change the structural properties of the surface. In the last two decades studies on the coupling of unsaturated hydrocarbons to inorganic surfaces have emerged. These compounds (also referred to as 1-alkenes and 1-alkynes) form covalently coupled monolayers on a variety of substrates, which is shortly reviewed in Chapter 1. This class of surface modification also forms the basis of the studies described in the following chapters. In Chapter 2, a method for the direct patterning of 1-alkynes onto hydrogen-terminated silicon is presented. The method combines microcontact printing with visible light illumination through the stamp. Since the surface modification is clearly enhanced by the illumination, the method was named light-enhanced microcontact printing (LE-µCP). It results in the local formation of an alkenyl monolayer at the areas where the stamp is in contact with the surface. The method is compatible with functional inks and also allows the preparation of chemically heterogeneous surfaces by backfilling of the uncontacted areas with a second functional ink. In Chapter 3, a method is introduced to photochemically modify fused silica substrates with 1-alkenes. This yields highly hydrophobic surfaces with high thermal stability, whereas the adsorbed layer provides proper chemical passivation of the underlying surface. The alkenes initially bind to the surface hydroxyl groups in Markovnikov fashion, but at prolonged reaction times oligomerization takes place. Since the reaction is photochemically initiated, it enables the use of photolithography to constructively pattern the silica surfaces. Because of this, the newly developed method forms a valuable addition to the existing modification methods. The method developed in Chapter 3 is applied in Chapter 4 to locally furnish silica surfaces with a functional linker. This has allowed the selective attachment of single-stranded DNA onto the modified areas. In addition to plain surfaces, the surface reaction is also demonstrated on onto curved, enclosed surfaces, i.e. the inner surface of a microchannel. The surface-bound DNA has been selectively and reversibly hybridized with the complementary DNA. These experiments show that ~ 7 ´1011 fluorescently labeled DNA molecules can be hybridized per cm2. By furnishing target compounds with the complementary DNA strand, this hybridization approach allows the selective, localized binding of proteins, antibodies and other biomolecules to the surface. In Chapter 5, a new method for the organic modification of porous anodic alumina (PAA) is presented, which is based on the reaction of terminal alkynes with the alumina surface. The reaction results in the formation of a monolayer within several hours at 80 °C and is dependent on both oxygen and light. These monolayers are well-defined and consist of an oxidation product of the 1-alkyne, i.e. its a-hydroxy carboxylate. The obtained monolayers are fairly stable in water and at elevated temperatures. Modification with 1,15-hexadecadiyne results in a surface with available alkyne endgroups, which can be used for further surface chemistry. In Chapter 6, the biofunctionalization of PAA is explored. To this aim, lactosyl-terminated surfaces are prepared and the subsequent adsorption of peanut agglutinin (PNA) is studied. The PNA binds selectively and reversibly to these surfaces. Moreover, PNA adsorption is higher on surfaces that expose the b-lactoside than on those that display the a-anomer, which is attributed to surface-associated steric hindrance. The adsorption of the pathogens Neisseria gonorrhoeae and Candida albicans onto the lactosylated PAA surfaces is also investigated. Whereas quantification of N. gonorrhoeae adsorption is hindered by high background staining, C. albicans shows increased colonization onto lactosylated surfaces. Thus, this chapter shows that aluminum oxide surfaces can be modified to induce selective adsorption of proteins and microorganisms. The studies in this thesis show that there is much to be explored in the surface modification of inorganic surfaces. Future studies could focus on the mechanism of the coupling reaction, but also on the reactivity of 1-alkenes and 1-alkynes towards other relevant inorganic materials. In addition, the surface modification with living cells and biofilms is still largely unexplored and may be a research topic of prime interest for the coming years!</p

Evaluation of European Land Data Assimilation System (ELDAS) products using in site observations

Three land-surface models with land-data assimilation scheme (DA) were evaluated for one growing season using in situ observations obtained across Europe. To avoid drifts in the land-surface state in the models, soil moisture corrections are derived from errors in screen-level atmospheric quantities. With the in situ data it is assessed whether these land-surface schemes produce adequate results regarding the annual range of the soil water content, the monthly mean soil moisture content in the root zone and evaporative fraction (the ratio of evapotranspiration to energy available at the surface). DA considerably reduced bias in net precipitation, while slightly reducing RMSE as well. Evaporative fraction was improved in dry conditions but was hardly affected in moist conditions. The amplitude of soil moisture variations tended to be underestimated. The impact of improved land-surface properties like Leaf Area Index, water holding capacity and rooting depth may be as large as corrections of the DA systems. Because soil moisture memorizes errors in the hydrological cycle of the models, DA will remain necessary in forecast mode. Model improvements should be balanced against improvements of DA per se. Model bias appearing from persistent analysis increments arising from DA systems should be addressed by model improvement

Future weather

The impact of climate change will manifest itself in our future weather. In the project Future Weather we investigated a number of these impact relevant weather conditions in the (present and) future climate. We focussed primarily on changes in precipitation extremes on different scales ranging from intense showers at local scales to multi-day precipitation extremes over the Rhine catchment area. On an intermediate scale, regional differences in precipitation within the Netherlands are studied. Finally, we considered a worst case scenario of a combined wind and discharge extreme

Theoretical and Experimental Study of the Absorption rate of H2S in CuSO4 Solutions. The Effect of Enhancement of Mass Transfer by a Precipitation Reaction

In this paper the desulphurization of gas streams using aqueous copper sulphate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulphurization is accomplished by a precipitation reaction that occurs when sulphide ions and metal ions are brought into contact with each other. Absorption experiments of H2S in aqueous CuSO4 solutions were carried out in a Mechanically Agitated Gas Liquid Reactor. The experiments were conducted at a temperature of 293 K and CuSO4 concentrations between 0.01 and 0.1 M. These experiments showed that the process efficiently removes H2S. Furthermore, the experiments indicate that the absorption of H2S in a CuSO4 solution may typically be considered a mass transfer limited process at, for this type of industrial process, relevant conditions. The extended model developed by Al-Tarazi et al. (2004) has been used to predict the rate of H2S absorption. This model describes the absorption and accompanying precipitation process in terms of, among others, elementary reaction steps, particle nucleation and growth. The results from this extended model and results obtained with a much simpler model, regarding the absorption of H2S in CuSO4 containing aqueous solutions as absorption of a gas accompanied by an instantaneous irreversible reaction were compared with experimental results. From this comparison it appeared that the absorption rate of H2S in a CuSO4 solution can, under certain conditions, be considered as a mass transfer rate controlled process. Under a much wider range of conditions the error that is made by assuming that the absorption process is a mass transfer controlled process, is still within engineering accuracy. Application of the simple model allows for a considerable reduction of the theoretical effort needed for the design of a gas-liquid contacting device, thereby still assuring that the desired gas specification can be met under a wide range of operating conditions. A comparison of the experimental results and the simulated results showed that the extended model gives an under prediction of the H2S absorption rate for the experimental conditions applied

Single-cell analysis of peptide expression and electrophysiology of right parietal neurons involved in male copulation behavior of a simultaneous hermaphrodite

Male copulation is a complex behavior that requires coordinated communication between the nervous system and the peripheral reproductive organs involved in mating. In hermaphroditic animals, such as the freshwater snail Lymnaea stagnalis, this complexity increases since the animal can behave both as male and female. The performance of the sexual role as a male is coordinated via a neuronal communication regulated by many peptidergic neurons, clustered in the cerebral and pedal ganglia and dispersed in the pleural and parietal ganglia. By combining single-cell matrix-assisted laser mass spectrometry with retrograde staining and electrophysiology, we analyzed neuropeptide expression of single neurons of the right parietal ganglion and their axonal projections into the penial nerve. Based on the neuropeptide profile of these neurons, we were able to reconstruct a chemical map of the right parietal ganglion revealing a striking correlation with the earlier electrophysiological and neuroanatomical studies. Neurons can be divided into two main groups: (i) neurons that express heptapeptides and (ii) neurons that do not. The neuronal projection of the different neurons into the penial nerve reveals a pattern where (spontaneous) activity is related to branching pattern. This heterogeneity in both neurochemical anatomy and branching pattern of the parietal neurons reflects the complexity of the peptidergic neurotransmission involved in the regulation of male mating behavior in this simultaneous hermaphrodite

Atmospheric CO2 modeling at the regional scale: an intercomparison of 5 meso-scale atmospheric models

Atmospheric CO2 modeling in interaction with the surface fluxes, at the regional scale is developed within the frame of the European project CarboEurope-IP and its Regional Experiment component. In this context, five meso-scale meteorological models participate in an intercomparison exercise. Using a common experimental protocol that imposes a large number of rules, two days of the CarboEurope Regional Experiment Strategy (CERES) campaign are simulated. A systematic evaluation of the models is done in confrontation with the observations, using statistical tools and direct comparisons. Thus, temperature and relative humidity at 2 m, wind direction, surface energy and CO2 fluxes, vertical profiles of potential temperature as well as in-situ CO2 concentrations comparisons between observations and simulations are examined. This intercomparison exercise shows also the models ability to represent the meteorology and carbon cycling at the synoptic and regional scale in the boundary layer, but also points out some of the major shortcomings of the models

Continuous Interaction with a Virtual Human

Attentive Speaking and Active Listening require that a Virtual Human be capable of simultaneous perception/interpretation and production of communicative behavior. A Virtual Human should be able to signal its attitude and attention while it is listening to its interaction partner, and be able to attend to its interaction partner while it is speaking – and modify its communicative behavior on-the-fly based on what it perceives from its partner. This report presents the results of a four week summer project that was part of eNTERFACE’10. The project resulted in progress on several aspects of continuous interaction such as scheduling and interrupting multimodal behavior, automatic classification of listener responses, generation of response eliciting behavior, and models for appropriate reactions to listener responses. A pilot user study was conducted with ten participants. In addition, the project yielded a number of deliverables that are released for public access

Optimized Trigger for Ultra-High-Energy Cosmic-Ray and Neutrino Observations with the Low Frequency Radio Array

When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency pulse is emitted. We plan to use the LOFAR radio telescope to detect these pulses. In this work we propose an efficient trigger implementation for LOFAR optimized for the observation of short radio pulses.Comment: Submitted to Nuclear Instruments and Methods in Physics Research Section

Zoetwatervoorziening in Nederland : landelijke analyse knelpunten in de 21e eeuw

Deze knelpuntenanalyse is een eerste stap in een verkenning van de zoetwaterproblematiek. Doel van de landelijke knelpuntenanalyse is om vast te stellen waar de toekomstige watervraag groter is dan de waterbeschikbaarheid, hetzij qua hoeveelheid, hetzij qua kwaliteit. Daartoe is de watervraag van diverse gebruikers in beeld gebracht, evenals de waterbeschikbaarheid, nu en in de toekomst. Voor het verkennen van de toekomst is gebruik gemaakt van deltascenario's

High unbound flucloxacillin fraction in critically ill patients

OBJECTIVES: To describe the unbound and total flucloxacillin pharmacokinetics in critically ill patients and to define optimal dosing strategies. PATIENTS AND METHODS: Observational multicentre study including a total of 33 adult ICU patients receiving flucloxacillin, given as intermittent or continuous infusion. Pharmacokinetic sampling was performed on two occasions on two different days. Total and unbound flucloxacillin concentrations were measured and analysed using non-linear mixed-effects modelling. Serum albumin was added as covariate on the maximum binding capacity and endogenous creatinine clearance (CLCR) as covariate for renal function. Monte Carlo simulations were performed to predict the unbound flucloxacillin concentrations for different dosing strategies and different categories of endogenous CLCR. RESULTS: The measured unbound concentrations ranged from 0.2 to 110 mg/L and the observed unbound fraction varied between 7.0% and 71.7%. An integral two-compartmental linear pharmacokinetic model based on total and unbound concentrations was developed. A dose of 12 g/24 h was sufficient for 99.9% of the population to achieve a concentration of >2.5 mg/L (100% fT>5×MIC, MIC = 0.5 mg/L). CONCLUSIONS: Critically ill patients show higher unbound flucloxacillin fractions and concentrations than previously thought. Consequently, the risk of subtherapeutic exposure is low