Leerredenen ter viering van het derde eeuwfeest der hervorming : gehouden te Amsterdam, op den 2 november 1817 /

Includes bibliographical references.

NMR spectroscopy in the presence of ultrasound and other perturbations

The work described in this thesis has been concerned with exploring the potential uses of ultrasound in Nuclear Magnetic Resonance (NMR) spectroscopy, The NMR spectra of liquids provide detailed structural information that may be deduced from the chemical shifts and spin-spin coupling, that are evident in the narrow resonances, arising from some of the nuclear broadening interactions being reduced to zero. In the solid state, all of the nuclear broadening interactions are present and broad lines in the NMR spectrum are observed. Current techniques employed to reduce the line widths in solids are based on coherent averaging techniques such as MAS NMR1,2 which can remove first order interactions. Recently DOR3 and DAS4 have become available to remove higher order interactions. SINNMR (Sonically Induced Narrowing of the NMR spectra of solids) has been reported by Homer et al5 and developed by Homer and Howard6 to reduce the line widths of solids. The basis of their work is the proposal that a colloidal suspension of solid particles can be made to move like large molecules by using ultrasonic agitation. The advantage of the technique is that the particles move incoherently removing all of the nuclear interactions responsible for broad lines. This thesis describes work on the extension of SINNMR by showing that the line width of 27AI and 11B for the glass Na20/B203/AI203 can be reduced by placing solid particles in a colloidal suspension. Further line width reduction is possible by applying ultrasound, at 2 MHz, of sufficient intensity. It is proposed that a cavitation field is responsible for imparting sufficient rotational motion to the solid particles to partially average the nuclear interactions responsible for broad lines. Rapid stirring of the colloidal suspension generates turbulent flow, however, the motion is insufficient to narrow the line widths for 27AI in the glass. Investigations of sonochemical reactions for in situ rate measurements by NMR have been made. 8y using the Weissler reaction7, it has been shown that ultrasonic cavitation is possible up to 10MHz. Preliminary studies have been carried out into the rate of ultrasonic polymerisation of methylmethacrylate by NMR. Long range order in liquid crystals can imposed when they are aligned in the presence a magnetic field. The degree of alignment can be monitored by NMR using, for example a deuterated solute added to the liquid crystal8. Ultrasonic streaming can then be employed to deflect the directors of the liquid crystal from their equilibrium position, resulting in a change In the NMR spectrum. The angle of deflection has been found for the thermotropic liquid crystal (I35) to be ca, 35° and for the lyotropic (ZLI-1167) to be ca, 20°, Mechanical stirring can used to re- orientate the liquid crystal but was found to give a smaller deflection, In a separate study, that did not use ultrasound, it has been found that the signal to noise ratio of 13C NMR signals can be enhanced by rapidly stirring a Iiquid. Accelerating the diffusion of nuclei out of the coil region enables M0 to be re-established more rapidly than the normal relaxation process. This allows the pulse repetition rate to be reduced without saturating the spin system. The influence of varying the relaxation delay, acquisition time and inter-pulse delay have been studied and parameters optimised. By studying cholesterol the technique was found to be most effective for nuclei with long relaxation times, such as quaternary carbon sites. Key Worde: NMR, Ulf.rasciund, 1,.lqi.fi!:l cryllltalt!h SCll1C1otlemlstryl I!r1hano~d algnflllf

Mediators of monocyte activity in inflammation

C-reactive protein (CRP) is the prototypic acute phase serum protein in humans. CRP is currently one of the best markers of inflammatory disease and disease activity. One of the keys cells involved in inflammation within chronic inflammatory diseases is the monocyte. Monocytes are able to modulate inflammation through cytokine expression, cytosolic peroxide formation, adhesion molecule expression and subsequent adhesion/migration to sites of inflammation. CRP has been previously shown to bind directly to monocytes through Fc receptors. However this observation is not conclusive and requires further investigation. The effects of incubation of CRP with human primary and monocytic cell lines were examined using monocytic cytokine expression, adhesion molecule expression and adhesion to endothelial cells and intracellular peroxide formation, as end points. Monocytic intracellular signalling events were investigated after interaction of CRP with specific CRP receptors on monocytes. These initial signalling events were examined for their role in modulating monocytic adhesion molecule and cytokine expression. Monocyte recruitment and retention in the vasculature is also influenced by oxidative stress. Therefore the effect of 6 weeks of antioxidant intervention in vivo was examined on monocytic adhesion molecule expression, adhesion to endothelial cells ex vivo and on serum CRP concentrations, pre- and post- supplementation with the antioxidants vitamin C and vitaInin E. In summary, CRP is able to bind FcγRIIa. CRP binding FcγR initiates an intracellular signalling cascade that phosphorylates the non-receptor tyrosine kinase, Syk, associated with intracellular tyrosine activating motifs on the cytoplasmic tail of Fcγ receptors. CRP incubations increased phosphatidyl inositol turnover and Syk phosphorylation ultimately lead to Ca2+ mobilisation in monocytes. CRP mediated Syk phosphorylation in monocytes leads to an increase in CD 11b and IL-6 expression. CRP engagement with monocytes also leads to an increase in peroxide production, which can be inhibited in vitro using the antioxidants α-tocopherol and ascorbic acid. CRP mediated CD 11b expression is not redox regulated by CRP mediated changes in cytosolic peroxides. The FcyRIla polymorphism at codon 131 effects the phenotypic driven changes described in monocytes by CRP, where R/R allotypes have a greater increase in CD11b, in response to CRP, which may be involved in promoting the monocytic inflammatory response. CRP leads to an increase in the expression of pro-inflammatory cytokines, which alters the immune phenotype of circulating monocytes. Vitamin C supplementation reduced monocytic adhesion to endothelial cells, but had no effect on serum levels of CRP. Where long-term antioxidant intervention may provide benefit from the risk of developing vascular inflammatory disease, by reducing monocytic adhesion to the vasculature. In conclusion CRP appears to be much more than just a marker of ongoing inflammation or associated inflammatory disease and disease activity. This data suggests that at pathophysiological concentrations, CRP may be able to directly modulate inflammation through interacting with monocytes and thereby alter the inflammatory response associated with vascular inflammatory diseases.

Intermediate pyrolysis and product identification by TGA and Py-GC/MS of green microalgae and their extracted protein and lipid components

The thermo-chemical conversion of green microalgae Chlamydomonas reinhardtii wild type (CCAP 11/32C), its cell wall deficient mutant C. reinhardtii CW15 (CCAP 11/32CW15) and Chlorella vulgaris (CCAP 211/11B) as well as their proteins and lipids was studied under conditions of intermediate pyrolysis. The microalgae were characterised for ultimate and gross chemical composition, lipid composition and extracted products were analysed by Thermogravimetric analysis (TG/DTG) and Pyrolysis-gaschromatography/mass-spectrometry (Py-GC/MS). Proteins accounted for almost 50% and lipids 16-22 % of dry weight of cells with little difference in the lipid compositions between the C. reinhardtii wild type and the cell wall mutant. During TGA analysis, each biomass exhibited three stages of decomposition, namely dehydration, devolatilization and decomposition of carbonaceous solids. Py-GC/MS analysis revealed significant protein derived compounds from all algae including toluene, phenol, 4-methylphenol, 1H-indole, 1H-indole-3methyl. Lipid pyrolysis products derived from C. reinhardtii wild type and C. reinhardtii CW15 were almost identical and reflected the close similarity of the fatty acid profiles of both strains. Major products identified were phytol and phytol derivatives formed from the terpenoid chain of chlorophyll, benzoic acid alkyl ester derivative, benzenedicarboxylic acid alkyl ester derivative and squalene. In addition, octadecanoic acid octyl ester, hexadecanoic acid methyl ester and hydrocarbons including heptadecane, 1-nonadecene and heneicosane were detected from C. vulgaris pyrolysed lipids. These results contrast sharply with the types of pyrolytic products obtained from terrestrial lignocellulosic feedstocks and reveal that intermediate pyrolysis of algal biomass generates a range of useful products with wide ranging applications including bio fuels.

Spectroscopy of Electroproduced Light to Medium Mass Lambda Hypernuclei

The E01-011 experiment at Jefferson Laboratory (JLab) studied light-to-medium mass Λ hypernuclei via the AZ + e → [special characters omitted] + e' + K+ electroproduction reaction. Precise measurement of hypernuclear ground state masses and excitation energies provides information about the nature of hyperon-nucleon interactions. Until recently, hypernuclei were studied at accelerator facilities with intense π+ and K- meson beams. The poor quality of these beams limited the resolution of the hypernuclear excitation energy spectra to about 1.5 MeV (FWHM). This resolution is not sufficient for resolving the rich structure observed in the excitation spectra. By using a high quality electron beam and employing a new high resolution spectrometer system, this study aims to improve the resolution to a few hundred keV with an absolute precision of about 100 keV for excitation energies. In this work the high-resolution excitation spectra of [special characters omitted], and [special characters omitted] hypernuclei are presented. In an attempt to emphasize the presence of the core-excited states we introduced a novel likelihood approach to particle identification (PID) to serve as an alternative to the commonly used standard hard-cut PID. The new method resulted in almost identical missing mass spectra as obtained by the standard approach. An energy resolution of approximately 400–500 keV (FWHM) has been achieved, an unprecedented value in hypernuclear reaction spectroscopy. For [special characters omitted] the core-excited configuration has been clearly observed with significant statistics. The embedded Λ hyperon increases the excitation energies of the 11B nuclear core by 0.5–1 MeV. The [special characters omitted] spectrum has been observed with significant statistics for the first time. The ground state is bound deeper by roughly 400 keV than currently predicted by theory. Indication for the core-excited doublet, which is unbound in the core itself, is observed. The measurement of [special characters omitted] provides the first study of a d-shell hypernucleus with sub-MeV resolution. Discrepancies of up to 2 MeV between measured and theoretically predicted binding energies are found. Similar disagreement exists when comparing to the [special characters omitted] mirror hypernucleus. Also the core-excited structure observed between the major s-, p- and d-shell Λ orbits is not consistent with the available theoretical calculations. In conclusion, the discrepancies found in this study will provide valuable input for the further development of theoretical models.

Global compilation of benthic data sets I

Approaches to quantify the organic carbon accumulation on a global scale generally do not consider the small-scale variability of sedimentary and oceanographic boundary conditions along continental margins. In this study, we present a new approach to regionalize the total organic carbon (TOC) content in surface sediments (<5 cm sediment depth). It is based on a compilation of more than 5500 single measurements from various sources. Global TOC distribution was determined by the application of a combined qualitative and quantitative-geostatistical method. Overall, 33 benthic TOC-based provinces were defined and used to process the global distribution pattern of the TOC content in surface sediments in a 1°x1° grid resolution. Regional dependencies of data points within each single province are expressed by modeled semi-variograms. Measured and estimated TOC values show good correlation, emphasizing the reasonable applicability of the method. The accumulation of organic carbon in marine surface sediments is a key parameter in the control of mineralization processes and the material exchange between the sediment and the ocean water. Our approach will help to improve global budgets of nutrient and carbon cycles.

Global data compilation of benthic data sets II

In this study we present a global distribution pattern and budget of the minimum flux of particulate organic carbon to the sea floor (J POC alpha). The estimations are based on regionally specific correlations between the diffusive oxygen flux across the sediment-water interface, the total organic carbon content in surface sediments, and the oxygen concentration in bottom waters. For this, we modified the principal equation of Cai and Reimers [1995] as a basic monod reaction rate, applied within 11 regions where in situ measurements of diffusive oxygen uptake exist. By application of the resulting transfer functions to other regions with similar sedimentary conditions and areal interpolation, we calculated a minimum global budget of particulate organic carbon that actually reaches the sea floor of ~0.5 GtC yr**-1 (>1000 m water depth (wd)), whereas approximately 0.002-0.12 GtC yr**-1 is buried in the sediments (0.01-0.4% of surface primary production). Despite the fact that our global budget is in good agreement with previous studies, we found conspicuous differences among the distribution patterns of primary production, calculations based on particle trap collections of the POC flux, and J POC alpha of this study. These deviations, especially located at the southeastern and southwestern Atlantic Ocean, the Greenland and Norwegian Sea and the entire equatorial Pacific Ocean, strongly indicate a considerable influence of lateral particle transport on the vertical link between surface waters and underlying sediments. This observation is supported by sediment trap data. Furthermore, local differences in the availability and quality of the organic matter as well as different transport mechanisms through the water column are discussed.

(Table 1, 2) Foraminifera biometric data, and boron isotopic composition of Globigerinoides sacculifer of sediments from the Ontong-Java Plateau

Sediment samples from the Ontong-Java Plateau in the Pacific and the 90° east ridge in the Indian Ocean were used to investigate whether shell size and early diagenesis affect d11B of the symbiont-bearing planktonic foraminifer Globigerinoides sacculifer. In pristine shells from both study locations we found a systematic increase of d11B and Mg/Ca with shell size. Shells in the sieve size class 515-865 µm revealed d11B values +2.1 to +2.3 per mil higher than shells in the 250-380 µm class. This pattern is most likely due to differences in symbiont photosynthetic activity and its integrated effect on the pH of the foraminiferal microenvironment. We therefore suggest smaller individuals must live at approximately 50-100 m water depth where ambient light levels are lower. Using the empirical calibration curve for d11B in G. sacculifer, only shells larger than 425 µm reflect surface seawater pH. Partial dissolution of shells derived from deeper sediment cores was determined by shell weight analyses and investigation of the shell surface microstructure by scanning electron microscopy. The d11B in partially dissolved shells is up to 2 per mil lower relative to pristine shells of the same size class. In agreement with a relatively higher weight loss in smaller shells, samples from the Ontong-Java Plateau show a more pronounced dissolution effect than larger shells. On the basis of the primary size effect and potential postdepositional dissolution effects, we recommend the use of shells that are visually pristine and, in the case of G. sacculifer, larger than 500 ?m for paleoreconstructions.

d11B and metal/Ca ratios versus size fractions in the Surface and deep dwelling species, ODP Holes 130-806B and 108-664C

We have assessed the reliability of several foraminifer-hosted proxies of the ocean carbonate system (d11B, B/Ca, and U/Ca) using Holocene samples from the Atlantic and Pacific oceans. We examined chemical variability over a range of test sizes for two surface-dwelling foraminifers (Globigerinoides sacculifer and Globigerinoides ruber). Measurements of d11B in G. ruber show no significant relationship with test size in either Atlantic or Pacific sites and appear to provide a robust proxy of surface seawater pH. Likewise there is no significant variability in the d11B of our Atlantic core top G. sacculifer, but we find that d11B increases with increasing test size for G. sacculifer in the Pacific. These systematic differences in d11B are inferred to be a consequence of isotopically light gametogenic calcite in G. sacculifer and its preferential preservation during postdepositional dissolution. The trace element ratio proxies of ocean carbonate equilibria, U/Ca and B/Ca, show systematic increases in both G. ruber and G. sacculifer with increasing test size, possibly as a result of changing growth rates. This behavior complicates their use in paleoceanographic reconstructions. In keeping with several previous studies we find that Mg/Ca ratios increase with increasing size fraction in our well-preserved Atlantic G. sacculifer but not in G. ruber. In contrast to previous interpretations we suggest that these observations reflect a proportionally larger influence of compositionally distinct gametogenic calcite in small individuals compared to larger ones. As with d11B this influences G. sacculifer but not G. ruber, which has negligible gametogenic calcite.

(Table 1) Boron concentration and d11B values of interstitial water from IODP Holes 308-U1319A, U1320A, U1322B and U1324B

The Integrated Ocean Drilling Program Expedition 308 (IODP308) drilled normal-pressured sediments from the Brazos-Trinity Basin IV and over-pressured sediments from the Ursa Basin on the northern slope of the Gulf of Mexico. The interstitial water samples from the normal-pressured basin show B concentrations and B isotopic compositions ranging from 255 to 631 µM (0.6 to 1.5 times of seawater value) and from +29.1 to +42.7 per mil (relative to NIST SRM 951), respectively. A wider range is observed both for B concentrations (292 to 865 µM, 0.7 to 2.1 times of seawater value) and d11B values (+25.5 to +43.2 per mil) of the interstitial water in the over-pressured basin. The down-core distribution of B concentrations and d11B values in the interstitial waters are sensitive tracers for assessing various processes occurring in the sediment column, including boron adsorption/desorption reactions involving clay minerals and organic matter in sediments as well as fluid migration and mixing in certain horizons and in the sediment column. In the normal-pressured basin adsorption/desorption reactions in shallow sediments play the major role in controlling the B content and B isotopic composition of the interstitial water. In contrast, multiple processes affect the B content and d11B of the interstitial water in the over-pressured Ursa Basin. There, the stratigraphic level of the maxima of B and d11B correspond to seismic reflectors. The intruded fluids along the seismic reflector boundary from high to low-topography mix with local interstitial water. Fluid flow is inferred in the Blue Unit (a coarse sandstone layer, connecting the high- to low-pressured region) from the freshening of interstitial water in Ursa Basin Site U1322, and upward flow by the overpressure expels fluid from the overburden above the Blue Unit.

(Table 1) Li, B and Sr isotopic composition and concentration in ODP Leg 209 samples

Spinel harzburgites from ODP Leg 209 (Sites 1272A, 1274A) drilled at the Mid-Atlantic ridge between 14°N and 16°N are highly serpentinized (50-100%), but still preserve relics of primary phases (olivine >= orthopyroxene >> clinopyroxene). We determined whole-rock B and Li isotope compositions in order to constrain the effect of serpentinization on d11B and d7Li. Our data indicate that during serpentinization Li is leached from the rock, while B is added. The samples from ODP Leg 209 show the heaviest d11B (+29.6 to +40.52 per mil) and lightest d7Li (-28.46 to +7.17 per mil) found so far in oceanic mantle. High 87Sr/86Sr ratios (0.708536 to 0.709130) indicate moderate water/rock ratios (3 to 273, on the average 39), in line with the high degree of serpentinization observed. Applying the known fractionation factors for 11B/10B and 7Li/6Li between seawater and silicates, serpentinized peridotite in equilibrium with seawater at conditions corresponding to those of the studied drill holes (pH: 8.2; temperature: 200 °C) should have d11B of +21.52 per mil and d7Li of +9.7 per mil. As the data from ODP Leg 209 are clearly not in line with this, we modelled a process of seawater-rock interaction where d11B and d7Li of seawater evolve during penetration into the oceanic plate. Assuming chemical equilibrium between fluid and a rock with d11B and d7Li of ODP Leg 209 samples, we obtain d11B and d7Li values of +50 to +60 per mil, -2 to +12 per mil, respectively, for the coexisting fluid. In the oceanic domain, no hydrothermal fluids with such high d11B have yet been found, but are predicted by theoretical calculations. Combining the calculated water/rock ratios with the d7Li and d11B evolution in the fluid, shows that modification of d7Li during serpentinization requires higher water/rock ratios than modification of d11B. Extremely heavy d11B in serpentinized oceanic mantle can potentially be transported into subduction zones, as the B budget of the oceanic plate is dominated by serpentinites. Extremely light d7Li is unlikely to survive as the Li budget is dominated by the oceanic crust, even at small fractions.

(Table 3) Geochemistry of borehole fluids of ODP Hole 137-504B

Circulation of seawater through basaltic basement for several million years after crustal emplacement has been inferred from studies of surface heat flow, and may play a significant role in the exchange of elements between the oceanic crust and seawater. Without direct observation of the fluid chemistry, interpretations regarding the extent and timing of this exchange must be based on the integrated signal of alteration found in sampled basalts. Much interest has thus been expressed in obtaining and analyzing fluids directly from basaltic formations. It has been proposed that open oceanic boreholes can be used as oceanic groundwater wells to obtain fluids that are circulating within the formation. Water samples were collected from the open borehole in Hole 504B prior to drilling operations on Leg 137, with the original intention of collecting formation fluids from the surrounding basaltic rocks. Past results have yielded ambiguous conclusions as to the origin of the fluids recovered-specifically, whether or not the fluids were true formation fluids or merely the result of reaction of seawater in the borehole environment. The chemistry of eight borehole fluid samples collected during Leg 137 is discussed in this paper. Large changes in major, minor, and isotopic compositions relative to unaltered seawater were observed in the borehole fluids. Compositional changes increased with depth in the borehole. The samples exhibit the effect of simple mixing of seawater, throughout the borehole, with a single reacted fluid component. Analysis and interpretation of the results from Leg 137 in light of past results suggest that the chemical signals observed may originate predominantly from reaction with basaltic rubble residing at the bottom of the hole during the interim between drilling legs. Although this endeavor apparently did not recover formation waters, information on the nature of reaction between seawater and basalt at the prevalent temperatures in Hole 504B (>160°C) has been gained that can be related to reconstruction of the alteration history of the oceanic crust. Isotopic analyses allow calculation of element-specific water/rock mass ratios (Li and Sr) and are related to the extent of chemical exchange between the borehole fluids and basalt.