The myeloid expressed EF-hand proteins display a diverse pattern of lipid raft association

AbstractEF-hand proteins are known to translocate to membranes, suggesting that they are involved in signaling events located in the cell membrane. Many proteins involved in signaling events associate cholesterol rich membrane domains, so called lipid rafts, which serve as platforms for controlled protein–protein interaction. Here, we demonstrate that the myeloid expressed EF-hand proteins can be distinguished into three classes with respect to their membrane association. Grancalcin, a myeloid expressed penta EF-hand protein, is constitutively located in lipid rafts. S100A9 (MRP14) and S100A8 (MRP8) are translocated into detergent resistant lipid structures only after calcium activation of the neutrophils. However, the S100A9/A8 membrane association is cholesterol and sphingolipid independent. On the other hand, the association of S100A12 (EN-RAGE) and S100A6 (calcyclin) with membranes is detergent sensitive. These diverse affinities to lipid structures of the myeloid expressed EF-hand proteins most likely reflect their different functions in neutrophils

On the existence and hydrolytic stability of titanosiloxane bonds in the system : glycidoxypropyltrimethoxysilane-water-titaniumtetraethoxide

Heterometal materials based on glycidoxypropyltrialkoxysilane and titaniumalkoxide are used for optical applications and require a high homogeneity on the molecular level. The presence of heterometal titanosiloxanes, their distribution and hydrolytic stability should influence the homogeneity of these materials. 29Si and 17O NMR spectroscopy has been used to investigate sols with molar ratios Si : Ti = 1 and H2O : OR (H) = 0.5-2.0 and their gels after heat treatment at 130°C. The presence of Si - O - Ti bonds in sols with a low water content (H < 0.2) and in the corresponding gels was identified by the high-field shift of the 29Si NMR signals of T1 and T2 units of up to 2-3 ppm compared to corresponding signals of homo-condensed Si - O - Si bonds. The existence of Si - O - Ti bonds in the sols is supported by 17O NMR spectra which show a characteristic signal around 340 ppm. A cleavage of the Si - O - Ti bonds occurs with increasing water/OR ratio in the sols. The cleavage of the heterometal bonds and the building up of homo-condensed species leads to a separation into areas with predominantly Ti - O - Ti and Si - O - Si bonds resulting in a decreased molecular homogeneity of the materials

Lernen im Dialog: Jugend - Wirtschaft - Politik: zwei Modellprogramme der betrieblichen Jugendbildung

Der Autor berichtet am Beispiel von zwei Modellprogrammen der Deutschen BP AG über die Entwicklung einer fachübergreifenden Jugendbildung in Unternehmen. Die Grundidee der 'Jugendseminare' und der 'Studienwochen für Lehrer und Schüler' ist, Jugendliche zur 'selbständigen Orientierung über Wirtschaft, Umwelt, Staat und Politik durch Lernen im Dialog zwischen Institutionen und Generationen' anzuregen. Im Anschluß an die ethischen und organisatorischen Prinzipien werden der Aufbau, der Ablauf und die Lernziele der beiden Programme skizziert. (KO

STUDY OF THE BEHAVIOUR OF A CATALYTIC CERAMIC CANDLE FILTER IN A LAB-SCALE UNIT AT HIGH TEMPERATURES

Solid particles and tars are among the non-desirable products of synthesis gas produced during biomass gasification. Removal of fly ashes is necessary in order to comply with emission limits as well as avoid their deposition in downstream units. Condensation of tars, on the other side, can cause clogging. A catalytic hot gas filter can remove both solids and tars, when operating at temperatures as high as 850oC. Catalytic hot gas filter elements are under development in order to solve this issue. A lab-scale filtration unit has been designed and constructed at Delft University of Technology. The unit contains one ceramic hot gas filter candle which is made of a SiC porous structure coated with a mullite membrane. The integration of a Nickel-based catalyst layer allows the dual function of particle filtration and tar cracking. The filter vessel is part of a set-up that is equipped with a tar evaporator and a pre-heater, both located upstream of the filter unit. This paper presents the results of the first set of experimental tests that have been performed with this unit. A dust-free model gas was used and consisted of a mixture of CO (14%), CO2 (14%), H2 (7%), CH4 (5%), and varying concentrations of N2 (30, 40, 50%) and H2O (30, 20, 10%). Naphthalene (2g/Nm3 and 5g/Nm3) was adopted as model compound in order to study the catalytic conversion of heavier hydrocarbon species to H2. A gas face velocity of 2.5cm/s was selected for tests performed at atmospheric conditions and at operating temperatures varying between 700oC and 850oC. The pressure drop through the filter candle was continuously monitored during the process. The gas composition was measured upstream and downstream of the filter unit by means of an on-line micro-GC, while naphthalene concentration was attained with the SPA method. The following findings were obtained: higher naphthalene conversion with increasing temperatures and better conversion at any temperature when 2g/Nm3 were used compared to 5g/Nm3. Tests at 850oC and 30 vol% H2O produced a conversion of 99.4% with 2g/Nm3 while 98.5% with 5g/Nm3. Experiments with higher steam content showed higher conversion values. Methane concentration was also affected thus indicating that reforming reactions took place as well. Pressure drop measurements showed that no carbon deposition occurred on the candle during the tests, even at lower temperatures. At this stage new experiments are being performed with different face velocities and tar compounds in order to provide enough data for future tests with real gasification gas

STUDY OF THE BEHAVIOUR OF A CATALYTIC CERAMIC CANDLE FILTER IN A LAB-SCALE UNIT AT HIGH TEMPERATURES

Solid particles and tars are among the non-desirable products of synthesis gas produced during biomass gasification. Removal of fly ashes is necessary in order to comply with emission limits as well as avoid their deposition in downstream units. Condensation of tars, on the other side, can cause clogging. A catalytic hot gas filter can remove both solids and tars, when operating at temperatures as high as 850oC. Catalytic hot gas filter elements are under development in order to solve this issue. A lab-scale filtration unit has been designed and constructed at Delft University of Technology. The unit contains one ceramic hot gas filter candle which is made of a SiC porous structure coated with a mullite membrane. The integration of a Nickel-based catalyst layer allows the dual function of particle filtration and tar cracking. The filter vessel is part of a set-up that is equipped with a tar evaporator and a pre-heater, both located upstream of the filter unit. This paper presents the results of the first set of experimental tests that have been performed with this unit. A dust-free model gas was used and consisted of a mixture of CO (14%), CO2 (14%), H2 (7%), CH4 (5%), and varying concentrations of N2 (30, 40, 50%) and H2O (30, 20, 10%). Naphthalene (2g/Nm3 and 5g/Nm3) was adopted as model compound in order to study the catalytic conversion of heavier hydrocarbon species to H2. A gas face velocity of 2.5cm/s was selected for tests performed at atmospheric conditions and at operating temperatures varying between 700oC and 850oC. The pressure drop through the filter candle was continuously monitored during the process. The gas composition was measured upstream and downstream of the filter unit by means of an on-line micro-GC, while naphthalene concentration was attained with the SPA method. The following findings were obtained: higher naphthalene conversion with increasing temperatures and better conversion at any temperature when 2g/Nm3 were used compared to 5g/Nm3. Tests at 850oC and 30 vol% H2O produced a conversion of 99.4% with 2g/Nm3 while 98.5% with 5g/Nm3. Experiments with higher steam content showed higher conversion values. Methane concentration was also affected thus indicating that reforming reactions took place as well. Pressure drop measurements showed that no carbon deposition occurred on the candle during the tests, even at lower temperatures. At this stage new experiments are being performed with different face velocities and tar compounds in order to provide enough data for future tests with real gasification gas

X-ray and NMR spectroscopic characterisation of cyclic titanodiphenylsiloxanes and examination of the hydrolytic stability of their Si-O-Ti bonds

Six crystalline titanodiphenylsiloxanes have been synthesised by reaction of diphenylsilanediol (DPSD) with titanium tetraisopropoxide or its complexes with acetylacetonate (acac) as ligand. Two of them show a spirocyclic structure with the formula TiO2[O2Si2(C6H5)(4)](2) A and TiO2[O4Si4(C6H5)(8)](2) B which have already been described in the literature. Two compounds C and D were identified by X-ray analysis to have the same bicyclic structure but different coordinating solvent molecules. Tetrahydrofuran acts as a non-bridging ligand at the Ti atoms in [Ti(acac)0(1.5)](2)[OSi(C6H5)(2)](3)?2C(4)H(8)O C while dioxane acts as a bridging ligand between the Ti atoms of neighbouring molecules of [Ti(acac)O-1.5](2)[OSi(C6H5)(2)](3)?3C(4)H(8)O(2) D. The titanodiphenylsiloxanes E and F were identified by a cyclotetrameric structure and the formulas [Ti(acac)(2)O](2)[OSi(C6H5)(2)](2) and [Ti(acac)(2)O][OSi(C6H5)(2)](3), respectively. The titanodiphenylsiloxanes A-E were characterised by Si-29 and O-17 NMR spectroscopy, IR and time-of-flight mass spectrometry measurements. The hydrolytic stabilities of the Si-O-Ti bonds in the titanodiphenylsiloxanes A-E have been examined mainly by means of Si-29 NMR spectroscopy. The results reveal a strong influence of the structure type of the titanodiphenylsiloxanes on the hydrolytic stability of their Si-O-Ti bonds apart from the hydrolytic conditions (amount of water, Si, Ti and H+ concentration). The hydrolytic stability of the titanodiphenylsiloxanes A-E decreases in the order cyclotetramer (E)> spirocyclo (A, B)> bicycle (C, D). Reasons for the different hydrolytic stability are discussed. The results on the different hydrolytic stabilities of Si-O-Ti bonds can contribute to a better understanding of the synthesis of homogeneous heterometal materials on a molecular scale via the sol-gel process