Repository hosted by TU Delft Library

Niet beschikbaar.

Bisphosphonates (Bps), inhibitors of osteoclastic bone resorption, are used in the treatment of skeletal disorders. Recent evidence indicated that farnesyl pyrophosphate (FPP) synthase and/or isopentenyl pyrophosphate (IPP) isomerase is the intracellular target(s) of bisphosphonate action. To examine which enzyme is specifically affected, we determined the effect of different Bps on incorporation of [14C]mevalonate (MVA), [14C]IPP, and [14C]dimethylallyl pyrophosphate (DMAPP) into polyisoprenyl pyrophosphates in a homogenate of bovine brain. HPLC analysis revealed that the three intermediates were incorporated into FPP and geranylgeranyl pyrophosphate (GGPP). In contrast to clodronate, the nitrogen-containing Bps (NBps), alendronate, risedronate, olpadronate, and ibandronate, completely blocked FPP and GGPP formation and induced in incubations with [14C]MVA a 3- to 5-fold increase in incorporation of label into IPP and/or DMAPP. Using a method that could distinguish DMAPP from IPP on basis of their difference in stability in acid, we found that none of the NBps affected the conversion of [14C]IPP into DMAPP, catalyzed by IPP isomerase, excluding this enzyme as target of NBp action. On the basis of these and our previous findings, we conclude that none of the enzymes up- or downstream of FPP synthase are affected by NBps, and FPP synthase is, therefore, the exclusive molecular target of NBp action. Chemicals/CAS: Carbon Radioisotopes; Carbon-Carbon Double Bond Isomerases, EC 5.3.3.-; Dimethylallyltranstransferase, EC 2.5.1.1; Diphosphonates; Enzyme Inhibitors; indolepropanol phosphate, 40716-80-1; Indoles; isopentenyldiphosphate delta-isomerase, EC 5.3.3.2; Mevalonic Acid, 150-97-0

The concept of reducing emissions of CO2 to the atmosphere by producing chemicals has been suggested by many people as a potential greenhouse gas mitigation option. The goal of such schemes is either: (i) fixation of CO2 in a chemical compound for a significant time, or, (ii) reduction of emissions by replacing an existing process with an alternative releasing less CO2. This paper describes a simple assessment procedure which can be used as a preliminary screen to test the validity of schemes for chemicals utilisation of CO2. The procedure is presented as a template (or worksheet); two summaries of its use are presented. The template gives research workers a decision methodology which leads to the proposed scheme either being rejected or accepted as being of sufficient potential to merit more detailed investigation. © 1997 Elsevier Science Ltd.

The corrosion behavior of the N80 casing and Cr13 steels was studied in a brine-CO2 mixture in autoclaves using electrochemical measurements and mass loss test. The brine solution contained 130 g/l NaCl, 22.2 g/l CaCl2 and 4 g/l MgCl2, representative for formation waters in North Sea wells. The objectives were to gain substantial cor-rosion data to ensure the selection of adequate casing material and to predict the service life of the casing under CO2 storage conditions. The N80 casing steel showed general corrosion and Cr13 showed pitting corrosion in the brine plus CO2 and 1%H2S. The Cr13 steel samples suffered more severe corrosion at the half-immersion position (the lower part in the liquid and the upper part in the gas phase) than at the complete immersion position.

In order to understand the membrane wetting in microporous hollow fiber membrane contactors, a theoretical model was developed by simulating CO 2 absorption in water under two extreme operating conditions of the non-wetted and wetted modes. The experimental studies on CO2 absorption using an aqueous DEA solution as the absorbent in a polypropylene hollow fiber membrane contactor were also conducted over a three-month period of time. Simulation results show that the CO2 absorption rate in the non-wetted mode is six times higher than those of the wetted mode of operation. The deteriorated performance in the wetted mode is mainly attributed to the mass transfer resistance imposed by the liquid in the membrane pores. The reduction of overall mass transfer coefficient may reach 20% even if the membrane pores were 5% wetted. Experimentally, the CO2 absorption in a 2 M DEA solution was found to be influenced by the gas flow rate significantly and the CO2 flux was enhanced by the increase of CO2 volume fraction in the feed stream. Moreover, in the Celgard microporous hollow fiber MiniModule®, the CO2 flux reduced about 20% in the initial 4 days of operation and then there was no change in the performance. The membrane wetting was identified to be the main reason responsible for the performance drop, as the membrane morphology and the overall mass transfer coefficient presented corresponding changes. The retrieval of the CO2 flux to 90% of the original amount was achieved by increasing the gas phase pressure, which further validated this hypothesis. Clearly, the prevention of the membrane wetting is very critical in maintaining the high performance of CO2 absorption in the membrane contactor.

Carbon and nitrogen cycling in intertidal mud flat sediments in the Scheldt Estuary was studied using measurements of carbon dioxide, methane and nitrous oxide emission rates and pore-water profiles of ΣCO2, ammonium and nitrate. A comparison between chamber measured carbon dioxide fluxes and those based on ΣCO2 pore-water gradients using Fick's First law indicates that apparent diffusion coefficients are 2 to 28 times higher than bulk sediment diffusion coefficients based on molecular diffusion. Seasonal changes in gaseous carbon fluxes or ΣCO2 pore water concentrations cannot be used directly, or in a simple way, to determine seasonal rates of mineralization, because of marked seasonal changes in pore-water storage and exchange parameters. The annual amount of carbon delivered to the sediment is 42 mol m-2, of which about 42% becomes buried, the remaining being emitted as methane (7%) or carbon dioxide (50%). Each year about 2.6 mol N m-2 of particulate nitrogen reaches the sediment; 1.1 mol m-2 is buried and 1.6 mol m-2 is mineralized to ammonium. Only 0.42 mol m-2 yr-1 of the ammonium produced escapes from the sediments, the remaining being first nitrified (1.2 mol m-2 yr-1) and then denitrified (1.7 mol m-2 yr-1). Simple calculations indicate that intertidal sediments may account for about 14% and 30% of the total estuarine retention of nitrogen and carbon, respectively. © 1995 Kluwer Academic Publishers.

Sequestering CO2 in aquifers is an attractive option for reducing CO2 emissions into the atmosphere. The success of CO2 sequestration during the Statoil Sleipner injection project proves that under the right conditions large volumes of CO2 can be stored in a water-bearing subsurface formation. In general, we know most of the injected CO2 will displace water and accumulate as free gas at the crest of the aquifer. © 2006 Society of Exploration Geophysicists.

Empirical relations between aerosol mass concentrations and Ångström parameters α were derived from simultaneous optical and chemical measurements on the Baltic in March 1998. The relations apply to mass concentrations of sea salt aerosol (SSA), black carbon (BC) and organic carbon (OC), expressed in terms of their ratio to the total particulate matter (TPM). Using these relations to calculate the mass concentrations of these aerosol components for a different season or a different area, yields favorable results. The relations were obtained and verified for Ångström parameters 0.2 ≤ α ≥ 1.43.

The European Committee for Standardisation (CEN) Technical Committee 264 'Air Quality' has recently produced a standard method for the measurements of organic carbon and elemental carbon in PM2.5 within its working group 35 in response to the requirements of European Directive 2008/50/EC. It is expected that this method will be used in future by all Member States making measurements of the carbonaceous content of PM2.5. This paper details the results of a laboratory and field measurement campaign and the statistical analysis performed to validate the standard method, assess its uncertainty and define its working range to provide clarity and confidence in the underpinning science for future users of the method. The statistical analysis showed that the expanded combined uncertainty for transmittance protocol measurements of OC, EC and TC is expected to be below 25%, at the 95% level of confidence, above filter loadings of 2 μg cm-2. An estimation of the detection limit of the method for total carbon was 2 μg cm-2. As a result of the laboratory and field measurement campaign the EUSAAR2 transmittance measurement protocol was chosen as the basis of the standard method EN 16909:2017. © 2017 The Royal Society of Chemistry. Chemicals/CAS: carbon, 7440-44-0

Industrial processes contribute significantly to global carbon dioxide emissions, with iron and steel manufacturing alone responsible for 6% of the total figure. The STEPWISE project, funded through the European Horizon 2020 (H2020) Low Carbon Energy (LCE) programme under grant agreement number 640769, is looking at reducing CO2 emissions in the iron and steel making industries. At the heart of this project is the ECN technology called sorption-enhanced water-gas shift (SEWGS), which is a solid sorption technology for CO2 capture from fuel gases such as blast furnace gas (BFG). This technology combines water-gas shift (WGS) in the WGS section with CO2/H2 separation steps in the SEWGS section. Scaling up of the SEWGS technology for CO2 capture from BFG and demonstrating it in an industrially relevant environment are the key objectives of the STEPWISE project, which are achieved by international collaboration between the project partners towards design, construction and operation of a pilot plant at Swerea Mefos, Luleå, Sweden, next to the SSAB steel manufacturing site. © 2018 Johnson Matthey.

An overview is given of various currently applied monitoring techniques for CO2 storage. Techniques are subdivided in correspondence to their applicability for monitoring three distinct realms. These are: - the atmosphere and the near-surface; - the overburden (including faults and wells); - the reservoir with its seals. Another subdivision can be made with respect to time, i.e. first monitoring during the injection and storage process and subsequently monitoring for the long term (after abandonment of the field). In this perspective, the importance of characterisation and monitoring before injection is addressed. Copyright © 2005, Institut français du pétrole.

A global emission inventory of carbon monoxide (CO) emissions with 1° × 1° latitude-longitude resolution was compiled for 1990 on a sectoral basis. The sectoral sources considered include large-scale biomass burning (29%, of which savanna burning, 18%, and deforestation, 11%), fossil fuel combustion (27%, predominantly in road transport), biofuel combustion (19%, predominantly fuelwood combustion), agricultural waste burning (21%) and industrial process sources (4%). The inventory was compiled using mostly national statistics as activity data, emission factors at global or country level, and specific grid maps to convert, by sector, country total emissions to the 1° × 1° grid. A special effort was made to compile a global inventory of biofuel use, since this was considered to be a significant source on a global level, and a major source in some regions such as India and China. The global anthropogenic source of CO in 1990 is estimated at about 974 Tg CO yr-1. The inventory is available on a sectoral basis on a 1° × 1° grid for input to global atmospheric models and on a regional/country basis for policy analysis. © 1999 Elsevier Science Ltd. All rights reserved.

Active packaging is one of the innovative food packaging concepts that has been introduced as a response to the continuous changes in current consumer demands and market trends. Major active packaging techniques are concerned with substances that absorb oxygen, ethylene, moisture, carbon dioxide, flavours/odours and those which release carbon dioxide, antimicrobial agents, antioxidants and flavours. The main objectives of this article are to. (1) provide a literature review about the different types of active packaging concepts with respect to mechanism of action, effectiveness and the effects on foods, (2) provide a state of the art about the experimental development and commercialization of active packaging concepts, (3) provide a scope of applications and (4) discuss the obstacles to be overcome in order to make extensive commercial application of active packaging in Europe feasible.

The use of membrane gas absorption for carbon dioxide production from flue gases is discussed with special reference to the combined supply of heat and carbon dioxide to greenhouses. Novel absorption liquids are introduced which show an improved performance in terms of system stability and mass transfer compared to monoethanolamine when used in combination with commercially available, inexpensive polyolefin membranes. It is shown that the combined supply of heat and carbon dioxide from cogeneration plants to greenhouses will lead to significant primary energy savings. Carbon dioxide can be produced by the membrane gas absorption process and delivered to greenhouses at lower cost than current supply methods. © 1997 Elsevier Science Ltd.

Different scenarios have been compared for the future reduction of CO2-emission under real-world driving conditions. A significant shift towards diesel appears hardly to benefit the CO2 but would carry a real NOx penalty. Introduction of DI petrol engines and a shift towards gaseous fuels for s.i. engines would have similar results for CO2, without this NOx penalty. Even so the possible gains are limited. The most effective way to obtain significant CO2 reductions for the EU car fleet in the longer term seems to be an all-out approach towards more fuel efficient vehicles in combination with innovative technologies. It is the aim of this paper to enable a more soundly based decision making.

Carbon tetrachloride (52 μM) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were sometimes also found as transformation products, but neither accumulated to significant levels in comparison to the amount of carbon tetrachloride transformed. Transformation of carbon tetrachloride in the absence of an added electron donor suggests that carbon tetrachloride itself is the source of energy for the biological reaction observed, and possibly the source of carbon for cell growth. No such mechanism is yet known. The pathway of carbon tetrachloride transformation is not clear; it may be dehalogenated by hydrolytic reduction to carbon monoxide or formic acid which are electron demanding transformations. Carbon monoxide or formic acid may be further utilized and serve as electron donor. Complete dechlorination of carbon tetrachloride according to this pathway is independent of a second electron donor or electron acceptor, as with a fermentation process. Vancomycin, an inhibitor of gram positive eubacteria, severely inhibited carbon tetrachloride transformation in batch incubations with an enrichment culture from the reactor, indicating that gram positive eubacteria were involved in carbon tetrachloride transformation. Batch experiments with bromoethanesulfonic acid, used to inhibit methanogens, and molybdate, an inhibitor of sulfate reduction in sulfate reducing bacteria, demonstrated that neither methanogens nor sulfate reducers were involved in the complete dechlorination of carbon tetrachloride.

In an on-going harmonized ESA/NIVR project, performed by Stork Comprimo and TNO-MEP, the removal of the carbon dioxide with membranes is studied. The use of membrane gas absorption for carbon dioxide removal is currently hampered by the fact that the commonly used alkanolamines result in leakage problems when using polyolefin membranes. This prevents the use of membrane gas absorption for carbon dioxide in spacecrafts. TNO has recently discovered classes of liquids for carbon dioxide absorption which are suitable for use with cheap polyolefin membranes. This opens the possibility for using membrane gas absorption for carbon dioxide control in spacecrafts. In the project the performance of membrane gas absorption for the removal of carbon dioxide from gas streams having a chemical composition representative of spacecraft conditions are determined experimentally. Important performance parameters are, among others, the required membrane area, equipment volume and weight and the used energy for a given duty. In this document, this new technique will be discussed and compared to other more mature carbon dioxide absorption techniques.

We present a model simulation for the year 1995 accounting for primary particles, which are an important component of fine aerosols over Europe. A new emission inventory for black carbon, (BC) was developed on the basis of the recent European emission inventory of anthropogenic primary particulate matter (Coordinated European Programme on Particulate Matter Emission Inventories, Projections and Guidance (CEPMEIP)). The annual BC emissions of Europe and the former Soviet Union for 1995 are estimated at 0.47 and 0.26 Tg C, respectively, with highest contributions from transport (off-road and on-road) and households. Modeled BC concentrations range from ≤0.05 μtg/m 3 in remote regions to more than 1 μtg/m3 over densely populated areas. The modeled BC concentration is about 25% of the total primary aerosol concentration. The primary aerosol fields were combined with previously calculated secondary aerosol concentrations to obtain an estimate of the total anthropogenic fine aerosol distribution. Modeled BC levels contribute only 4 10% to fine aerosol mass, whereas sulphate and nitrate contribute 25-50 and 5-35%, respectively. Comparison with experimental data revealed that the model underestimates PM2.5 levels, mostly caused, by the underprediction of total carbonaceous material (BC and OC) by a factor of ε12. The underestimation can partly be explained by the influence of local emissions, measurement uncertainties, natural sources, and representation of wet deposition. However, the uncertainties associated with the emission inventory for BC (and total PM) may be the most important cause for the discrepancy. In comparison with previous studies, our BC emission estimate is a factor of 2 lower, caused by the choice of more recent emission factors. Therefore a better knowledge of emission factors is urgently needed to. estimate the BC (and PM) emissions reliably. Copyright 2004 by the American Geophysical Union.