Mass spectrometry as a tool study CVD process

Mass spectrometry as a tool study CVD process. Application of two mass spectrometric (MS) techniques to study chemical vapour deposition from organometallic precursors is described. CpCuPEt3 (Cp = η5-C5H5, Et =C2H5) was used as a model precursor in this work

Drawing Under Construction

Abstract The thesis, Drawing Under Construction navigates notions of invisible labor, repetition, and endurance. I explore aspects of labor and movement through the use of drawing, installation, performance, and video. Unseen work, an exercise of emotional control, is central to this investigation, transforming notions of invisibility and visibility into tools to explore three concepts; Unfolding the Line, , The Line Under Construction, and Locating the Line. It is through these three areas of study that I further analyze “my hand” versus “the universal hand” and “my body” versus “the universal body” and create a system where my body and work live in an expansive and fluctuating ecosystem in constant evolution

CVD of pure copper films from amidinate precursor

Copper(I) amidinate [Cu(i-Pr-Me-AMD)]2 was investigated to produce copper films in conventional low pressure chemical vapor deposition (CVD) using hydrogen as reducing gas-reagent. Copper films were deposited on steel, silicon, and SiO2/Si substrates in the temperature range 200–350°C at a total pressure of 1333 Pa. The growth rate on steel follows the surface reaction between atomic hydrogen and the entire precursor molecule up to 240°C. A significant increase of the growth rate at temperatures higher than 300°C was attributed to thermal decomposition of the precursor molecule. It is shown that [Cu(i-Pr-Me-AMD)]2 meets the specifications for the metal organic chemical vapor deposition of Cu-based alloy coatings containing oxophilic elements such as aluminum

Flow generated by radial flow impellers: PIV measurements and CFD simulations

Particle image velocimetry (PIV) and computational fluid dynamics (CFD) have been used to investigate the single phase and gas-liquid flow generated by a Scaba SRGT turbine. The key details of the trailing vortices, the turbulent flow around the impeller blades and the accumulation of gas have been studied by using PIV measurements and CFD simulations. Both the experimental and numerical results show that the flow and the trailing vortices are not altered significantly upon gassing. The simulated results are generally in good agreement with the experimental findings. The CFD simulations also show that only small low-pressure regions exist behind the blades of the Scaba turbine compared with the very large lowpressure zones formed by the Rushton turbine. These results enable better understanding of the improved performance of the Scaba turbine for gas-liquid dispersions compared with the Rushton turbine

Thermal behaviour of CpCuPEt3 in gas phase and Cu thin films processing

Decomposition of CpCuPEt3 (Cp=NNN(η5-C5H5)) and MOCVD of Cu films from CpCuPEt3 have been investigated in the frame of an ongoing project on the processing of Cu-containing coatings. The behaviour of CpCuPEt3 vapours under heating conditions was studied by in situ mass spectrometry. It was established that this compound is monomeric in gas phase. Its decomposition mechanism on hot surface was proposed. From mass spectroscopy experiments, it was established that decomposition in vacuum begins at 150 °C with evolution of PEt3. Beyond 270 °C, formation of cyclopentadiene is observed, indicating that a change in decomposition mechanism occurs. The saturating vapour pressure of CpCuPEt3 was estimated through static method, in order to optimize transport conditions and to control the molar fraction of the precursor in the gas phase. Finally, growth rate and microstructure of MOCVD processed Cu films from CpCuPEt3 have been investigated

Methane, carbon dioxide and nitrous oxide emissions from two clear-water and two turbid-water urban ponds in Brussels (Belgium)

Shallow ponds can exist in a clear-water state dominated by macrophytes or a turbid-water state dominated by phytoplankton, but it is unclear if these two states affect differently carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions to the atmosphere. Two clear-water urban ponds (Silex and Tenreuken) dominated by macrophytes, and two turbid-water urban ponds (Leybeek and Pêcheries) dominated by phytoplankton, in the city of Brussels (Belgium), were sampled 46 times between June 2021 and December 2023 to measure the partial pressure of CO2 (pCO2), dissolved CH4 concentration, N2O saturation level (%N2O), and ancillary variables. CH4 ebullitive fluxes were also measured in the four ponds during 8 deployments, totally 48 days of cumulated measurements. The 13C/12C ratio of CH4 (δ13C-CH4) was measured in bubbles from the sediment and in water to decipher the pathway of sedimentary methanogenesis (acetoclastic or hydrogenotrophic) and quantify methane oxidation (MOX) in the water column. The pCO2 and CH4 values in the sampled urban ponds correlated with precipitation and water temperature, respectively. The %N2O values did not correlate with dissolved inorganic nitrogen (DIN) nor other variables for the individual ponds, but a positive relation to DIN emerged from the combined data-set for the four ponds. The sampled turbid-water and clear-water ponds did not show differences in terms of diffuse emissions of CO2 and N2O. Clear-water ponds exhibited higher values of annual ebullitive CH4 fluxes compared to turbid-water ponds, most probably in relation to the delivery to sediments of organic matter from macrophytes. At seasonal scale, CH4 fluxes between the surface of the ponds and the atmosphere exhibited a temperature dependence in all four ponds, with ebullitive CH4 fluxes having a stronger dependence to temperature than diffusive CH4 fluxes. The temperature sensitivity of ebullitive CH4 fluxes was different among the four ponds and decreased with increasing water depth. During summer 2023, hydrogenotrophic methanogenesis pathway seemed to dominate in clear-water ponds and acetoclastic methanogenesis pathway seemed to dominate in turbid-water ponds, as indicated by the δ13C-CH4 values of bubbles sampled by physically perturbing sediments. The δ13C-CH4 values of bubbles sampled during bubble trap deployments in 2021–2023 indicated a seasonal shift to hydrogenotrophic methanogenesis pathway in fall compared to spring and summer, when acetoclastic methanogenesis pathway seemed to dominate. The δ13C-CH4 of dissolved CH4 indicated higher rates of MOX in turbid-water ponds compared to clear-water ponds, with an overall positive correlation with total suspended matter (TSM) and Chlorophyll-a (Chl-a) concentrations. The presence of suspended particles putatively enhanced MOX by reducing light inhibition of MOX and/or by serving as substrate for fixed methanotrophic bacteria in the water column. Total CH4 emissions in CO2 equivalents either equalized or exceeded those of CO2 in most ponds, while N2O emissions were negligible compared to the other two greenhouse gases (GHGs). Total annual GHG emissions in CO2 equivalents from all four ponds increased from 2022 to 2023 due to higher CO2 diffusive fluxes, likely driven by higher annual precipitation in 2023 compared to 2022, possibly in response to the intense El Niño event of 2023

Estimated glomerular filtration rate is a poor predictor of the concentration of middle molecular weight uremic solutes in chronic kidney disease

Background: Uremic solute concentration increases as Glomerular Filtration Rate (GFR) declines. Weak associations were demonstrated between estimated GFR (eGFR) and the concentrations of several small water-soluble and protein-bound uremic solutes (MW500Da). Materials and Methods: In 95 CKD-patients (CKD-stage 2-5 not on dialysis), associations between different eGFR-formulae (creatinine, CystatinC-based or both) and the natural logarithm of the concentration of several LMWP's were analyzed: i.e. parathyroid hormone (PTH), Cystatin C (CystC), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), leptin, retinol binding protein (RbP), immunoglobin light chains kappa and lambda (Ig-kappa and Ig-lambda), beta-2-microglobulin (beta M-2), myoglobin and fibroblast growth factor-23 (FGF-23)). Results: The regression coefficients (R-2) between eGFR, based on the CKD-EPI-Crea-CystC-formula as reference, and the examined LMWP's could be divided into three groups. Most of the LMWP's associated weakly (R-2 0.7). Almost identical R-2-values were found per LMWP for all eGFR-formulae, with exception of CystC and beta M-2 which showed weaker associations with creatinine-based than with CystC-based eGFR. Conclusion: The association between eGFR and the concentration of several LMWP's is inconsistent, with in general low R-2-values. Thus, the use of eGFR to evaluate kidney function does not reflect the concentration of several LMWP's with proven toxic impact in CKD

Chemical vapor deposition of iron, iron carbides, and iron nitride films from amidinate precursors

Iron bis(N,N-diisopropylacetamidinate) [Fe2(µ-iPr-MeAMD)2(2-iPr-MeAMD)2] and iron bis(N,N-di-tert-butylacetamidinate) [Fe(tBu-MeAMD)2] were used as precursors for the metallorganic chemical vapor deposition (MOCVD) of iron-containing compounds including pure iron, iron carbides, Fe3C and Fe4C, and iron nitrides Fe4C. Their decomposition mechanism involves hydrogen migration followed by dissociation of the Fe–N bond and the release of free hydrogenated ligand (HL) and radicals. Surface intermediates are either released or decomposed on the surface providing Fe–N or Fe–C bonds. MOCVD experiments were run at 10 Torr, in the temperature ranges of 350–450°C with Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 and 280–350°C with Fe(tBu-MeAMD)2. Films prepared from Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 contain Fe, Fe3C, and Fe4C. Those prepared from Fe(tBu-MeAMD)2 contain Fe, Fe3C, and also Fe4C or Fe4N, depending on the temperature and hydrogen to precursor ratio (H/P) in the input gas. The room-temperature coercive field of films processed from Fe(tBu-MeAMD)2 is 3 times higher than that of the high temperature processed Fe4N films