Publications by authors named "Andreas Siegfried Braeuer"
Article Synopsis
- An advanced manufacturing process for aerogel-lined capillaries is introduced, which are used as liquid-core waveguides to enhance the Raman signal from aqueous samples.
- This new method improves upon previous spin-coating techniques by allowing for longer capillaries, adjustable lining thickness through lining velocity, and consistently crack-free linings.
- Key parameters influencing the fabrication process and their impacts on the aerogel lining's thickness and surface structure are analyzed using scanning electron microscopy to optimize the Raman signal gain.
We report an experimental study on the gain of the Raman signal of aqueous mixtures and liquid water when confined in aerogel-lined capillaries of various lengths of up to 20 cm and various internal diameters between 530 and 1000 µm. The lining was made of hydrophobised silica aerogel, and the carrier capillary body consisted of fused silica or borosilicate glass. Compared to the Raman signal detected from bulk liquid water with the same Raman probe, a Raman signal 27 times as large was detected when the liquid water was confined in a 20 cm-long capillary with an internal diameter of 700 µm.
View Article and Find Full Text PDFDue to the worldwide growing population, the demand on food increases, which results in the need for a higher productivity in agriculture. Generally, this leads to larger amounts of agricultural residues and by-products, which may cause severe environmental risks due to emissions from simple burning or storing, especially in emerging and developing countries. In Vietnam agricultural by-products arise in total of 118 Mt per year, whereas 80% are coming from rice and sugar cane processing.
View Article and Find Full Text PDFArticle Synopsis
- The study introduces a method for analyzing hydrogen bond networks (HBNs) in mixtures of water and various organic solvents using optical techniques.
- It employs experimental and computed Raman spectra to examine how hydrogen bonds form between different molecules in these mixtures.
- Results indicate that the composition and temperature significantly affect the development of HBNs in the mixtures, highlighting the interactions between water and the organic solvents.
Article Synopsis
- Microemulsions are commonly used in advanced material and chemical processing but often require large amounts of surfactants, posing economic and ecological challenges.
- Researchers have explored surfactant-free microemulsion-like systems utilizing carbon dioxide in a water/organic-solvent/CO mixture, which creates unique "water-rich" nanodomains within a "water-depleted" matrix.
- These systems feature pressure-responsive nanostructuration, allowing for rapid and reversible mixing and demixing of contents, making them promising for molecular material processing and chemical engineering applications due to their contaminant-free nature and ability to dissolve various molecules.
Article Synopsis
- This study looks at using in situ Raman spectroscopy to monitor how fruits, specifically mango and persimmon, are dried using supercritical carbon dioxide (SC-CO₂).
- The experiments were done at high pressure (10 MPa) and temperature (313 K), focusing on changes in water content and fruit structure during drying.
- The findings show that using a 532 nm excitation wavelength provides better quality spectra compared to 785 nm, and that CO₂ absorption helps improve water extraction from the fruit.
Article Synopsis
- A comprehensive understanding of sprays is currently lacking due to incomplete knowledge of heat- and mass-transport mechanisms.
- A new Raman evaluation technique is presented, allowing simultaneous measurement of droplet temperature, evaporation progress, and air entrainment in sprays.
- The effectiveness of this technique is validated through comparisons with thermodynamic equilibrium computations, enhancing existing optical spray diagnostics.