scholarly journals Acetic Acid Etching of Mg-xGd Alloys

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 117 ◽  
Author(s):  
Marcjanna Maria Gawlik ◽  
Björn Wiese ◽  
Alexander Welle ◽  
Jorge González ◽  
Valérie Desharnais ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Surface Morphology ◽  
Surface Characterization ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Mass Spectrometry Analysis ◽  
Material Degradation ◽  
Near Surface ◽  
Spectrometry Analysis ◽  
Chemical Surface

Mg-xGd alloys show potential to be used for degradable implants. As rare earth containing alloys, they are also of special interest for wrought products. All applications from medical to engineering uses require a low and controlled degradation or corrosion rate without pitting. Impurities from fabrication or machining, like Fe inclusions, encourage pitting, which inhibits uniform material degradation. This work investigates a suitable etching method to remove surface contamination and to understand the influence of etching on surface morphology. Acetic acid (HAc) etching as chemical surface treatment has been used to remove contamination from the surface. Extruded Mg-xGd (x = 2, 5 and 10) discs were etched with 250 g/L HAc solution in a volume of 5 mL or 10 mL for different times. The microstructure in the near surface region was characterized. Surface characterization was done by SEM, EDS, interferometry, and ToF-SIMS (time-of-flight secondary ion mass spectrometry) analysis. Different etching kinetics were observed due to microstructure and the volume of etching solution. Gd rich particles and higher etching temperatures due to smaller etchant volumes promote the formation of pits. Removal of 2–9 µm of material from the surface was sufficient to remove surface Fe contamination and to result in a plain surface morphology.

Spectrophotometry Measurement of Polynuclear Aromatic Hydrocarbons in Hamilton Harbour Sediments

1991 ◽  
Vol 26 (1) ◽  
pp. 1-16 ◽  
Author(s):  
T.P. Murphy ◽  
H. Brouwer ◽  
M.E. Fox ◽  
E. Nagy
Keyword(s):  
Aromatic Hydrocarbons ◽  
Total Concentration ◽  
Coal Tar ◽  
Sediment Cores ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Near Surface ◽  
Spectrometry Analysis ◽  
Hamilton Harbour

Abstract Eighty-one sediment cores were collected to determine the extent of coal tar contamination in a toxic area of Hamilton Harbour. Over 800 samples were analyzed by a UV spectrophotometric technique that was standardized with gas chromatography/mass spectrometry analysis. The coal tar distribution was variable. The highest concentrations were near the Stelco outfalls and the Hamilton-Wentworth combined sewer outfalls. The total concentration of the 16 polynuclear aromatic hydrocarbons (PAHs) in 48,300 m3 of near-surface sediments exceeded 200 µg/g.

scholarly journals Association of Increased Circulating Acetic Acid With Poor Survival in Pseudomonas aeruginosa Ventilator-Associated Pneumonia Patients

2021 ◽  
Vol 11 ◽  
Author(s):  
Xiaoling Qi ◽  
Li Zhang ◽  
Jing Xu ◽  
Zheying Tao ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acetic Acid ◽  
Short Chain Fatty Acids ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Ventilator Associated Pneumonia ◽  
Fermentation Products ◽  
Spectrometry Analysis ◽  
Beneficial Effects ◽  
Microbial Dysbiosis

BackgroundWe previously found that microbial disruption in Pseudomonas aeruginosa ventilator-associated pneumonia (PA-VAP) patients are long-lasting. Long-term microbial dysbiosis may lead to changes in metabolites. Short-chain fatty acids (SCFAs) are microbial fermentation products and show beneficial effects in patients with pneumonia. In this study, we aimed to explore the association between circulating SCFA levels and clinical outcomes in patients with PA-VAP.MethodsIn this study, we analyzed SCFAs in the serum of 49 patients with PA-VAP by gas chromatography-mass spectrometry analysis. Twenty of these patients died, and 29 survived. The correlation between serum SCFAs and patient survival and immune parameters was analyzed.ResultsWe developed a partial least squares discriminant analysis (PLS-DA) model to examine differential SCFAs in 49 patients with PA-VAP. Among the seven SCFAs, only acetic acid was increased in non-survivors (P = 0.031, VIP > 1). Furthermore, high levels of acetic acid (>1.96ug/ml) showed increased 90-day mortality compared to low levels of acetic acid (<1.96ug/ml) in Kaplan-Meier survival analyses (P = 0.027). Increased acetic acid also correlated with reduced circulating lymphocyte and monocyte counts.ConclusionOur study showed that increased circulating acetic acid is associated with 90-day mortality in PA-VAP patients. The decrease in lymphocytes and monocytes might be affected by acetic acid and involved in the poor prognosis.

Calculation of Membrane Lipid Ratios Using Single-Pixel Time-of-Flight Secondary Ion Mass Spectrometry Analysis

2015 ◽  
Vol 87 (15) ◽  
pp. 7795-7802 ◽  
Author(s):  
Rainer Kassenböhmer ◽  
Felix Draude ◽  
Martin Körsgen ◽  
Andreas Pelster ◽  
Heinrich F. Arlinghaus
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Time Of Flight ◽  
Membrane Lipid ◽  
Mass Spectrometry Analysis ◽  
Spectrometry Analysis ◽  
Lipid Ratios ◽  
Ion Mass Spectrometry ◽  
Secondary Ion ◽  
Single Pixel

scholarly journals Production of value-added chemicals from esterification of waste glycerol over MCM-41 supported catalysts

2019 ◽  
Vol 8 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Emine Kaya Ekinci ◽  
Nuray Oktar
Keyword(s):  
Acetic Acid ◽  
High Selectivity ◽  
Supported Catalysts ◽  
Value Added ◽  
Mass Spectrometry Analysis ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Glycerol Conversion ◽  
Spectrometry Analysis ◽  
Mcm 41

Abstract A series of active and selective MCM-41 supported catalysts have been successfully prepared and used for bioderived glycerol esterification with acetic acid to produce fuel additives. In the synthesis of MCM-41, an acidic hydrothermal synthesis route was used, and silicotungstic acid (STA) and zirconia (ZrO2) were added to the catalyst structure by wet impregnation. X-ray diffraction, nitrogen adsorption-desorption methods, scanning electron microscopy with energy-dispersive spectroscopy, and inductively coupled plasma-mass spectrometry analysis were used for characterizations of the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy analyses of pyridine-adsorbed catalysts owns Lewis and Brønsted acidity hosting in one, which promotes the esterification reaction of glycerol into glycerol esters with high selectivity. Esterification of glycerol reactions were performed at temperature intervals of 105°C–200°C, with an amount of catalyst equal to 0.5 g, and glycerol/acetic acid molar ratio of 1:6 in a stirred autoclave reactor operated batchwise. STA and ZrO2-impregnated MCM-41 catalysts showed better performance with a complete glycerol conversion and high selectivity to triacetin.

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