Interdisciplinary Undergraduate Laboratory for an Integrated Chemistry/Biology Program: Synthesis of Silver Nanoparticles (AgNPs)-Cellulose Composite Materials with Antimicrobial Activity.

This laboratory exercise integrates chemistry and biology concepts to give third/fourth-year undergraduate students an opportunity to apply knowledge from different subject areas to address a real-world biomedical issue such as pathogen inhibition using composite materials. It involves the preparation of a bacteria-derived cellulosic biopolymer through microbial cultivation, impregnation of the bacterial cellulose (BC) with silver nanoparticles (AgNPs), followed by the analysis of the materials and the antimicrobial properties of the biomaterial-AgNPs composites. The methods are relatively simple and use inexpensive chemicals.

Speciation and Proton Conductivity of Phosphoric Acid Confined in Mesoporous Silica.

Phosphoric acid (PA) confined in a commercial mesoporous silica (CARIACT G) with porous size in the range of 3 to 10 nm was studied in relation to its coordination with the silanol groups on the silica surface as a function of temperature, up to 180 °C, using P and Si MAS NMR spectroscopy. As the temperature increases, the coordination of Si and P in the mesopores depends on the pore size, that is, on the area/volume ratio of the silica matrix. In the mesoporous silica with the higher pore size (10 nm), a considerable fraction of PA is nonbonded to the silanol groups on the surface, and it seems to be responsible for its higher conductivity at temperatures above 120 °C as compared to the samples with a smaller pore size.

Triborate Formation Constants and Polyborate Speciation under Hydrothermal Conditions by Raman Spectroscopy using a Titanium/Sapphire Flow Cell.

Solvent-corrected reduced isotropic Raman spectra of aqueous boric acid + sodium borate solutions have been obtained from perpendicular and parallel polarization measurements in a novel custom-made titanium flow cell with sapphire windows over the temperature range 25 to 300 °C at 20 MPa using the perchlorate anion, ClO, as an internal standard. The reduced isotropic spectra of solutions yielded the first reported quantitative speciation results for polyborate ions in equilibrium with boric acid and borate in high-temperature aqueous solutions above 200 °C. The spectra obtained from solutions at low sodium/boron ratios, 0 < m/ m < 0.

Experimental and Theoretical Study of the High-Temperature UV-Visible Spectra of Aqueous Hydroquinone and 1,4-Benzoquinone.

UV-visible spectroscopic studies of aqueous hydroquinone (HQ) and 1,4-benzoquinone (BQ) have been carried out along with classical molecular dynamics (MD) and quantum calculations. The experimental results confirmed that HQ is stable in hot compressed water up to at least 523 K at 70 bar, but BQ decomposes at temperatures lower than 373 K, leading to the formation of HQ and other nonabsorbing products. Even though benzoquinone is not stable, our study significantly extended the temperature range of other spectroscopic studies, and the spectra of HQ up to 523 K can still be useful for other studies, particularly those related to organic species in deep ocean hydrothermal vents.

Apparent and standard partial molar volumes of NaCl, NaOH, and HCl in water and heavy water at T = 523 K and 573 K at p = 14 MPa.

Apparent molar volumes, Vphi,2, of aqueous NaCl, NaOH, NaOD, HCl, and DCl in water and heavy water were determined at T = 523 and 573 K and p = 14 MPa with a high-temperature platinum vibrating-tube densimeter in the aquamolality range 0.25 View Article and Find Full Text PDF