Articles by Adam D. Wexler in JoVE
The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids Adam D. Wexler1, Mónica López Sáenz2, Oliver Schreer2, Jakob Woisetschläger3, Elmar C. Fuchs1 1Applied Water Physics, Wetsus - Centre of Excellence for Sustainable Water Technology, 2IRCAM GmbH, 3Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology Horizontal and vertical electrohydrodynamic liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields and polar dielectric liquids. The construction of basic apparatus and operational examples, including thermographic images, for three liquids (e.g., water, DMSO, and glycerol) is presented.
Other articles by Adam D. Wexler on PubMed
Ultrafast Vibrational Energy Relaxation of the Water Bridge Physical Chemistry Chemical Physics : PCCP. May, 2012 | Pubmed ID: 21997703 We report the energy relaxation of the OH stretch vibration of HDO molecules contained in an HDO:D(2)O water bridge using femtosecond mid-infrared pump-probe spectroscopy. We found that the vibrational lifetime is shorter (~630 ± 50 fs) than for HDO molecules in bulk HDO:D(2)O (~740 ± 40 fs). In contrast, the thermalization dynamics following the vibrational relaxation are much slower (~1.5 ± 0.4 ps) than in bulk HDO:D(2)O (~250 ± 90 fs). These differences in energy relaxation dynamics strongly indicate that the water bridge and bulk water differ on a molecular scale.
Contraction-Induced Changes in Hydrogen Bonding of Muscle Hydration Water The Journal of Physical Chemistry Letters. Mar, 2014 | Pubmed ID: 24803993 Protein-water interaction plays a crucial role in protein dynamics and hence function. To study the chemical environment of water and proteins with high spatial resolution, synchrotron radiation-Fourier transform infrared (SR-FTIR) spectromicroscopy was used to probe skeletal muscle myofibrils. Observing the OH stretch band showed that water inside of relaxed myofibrils is extensively hydrogen-bonded with little or no free OH. In higher-resolution measurements obtained with single isolated myofibrils, the water absorption peaks were relatively higher within the center region of the sarcomere compared to those in the I-band region, implying higher hydration capacity of thick filaments compared to the thin filaments. When specimens were activated, changes in the OH stretch band showed significant dehydrogen bonding of muscle water; this was indicated by increased absorption at ∼3480 cm(-1) compared to relaxed myofibrils. These contraction-induced changes in water were accompanied by splitting of the amide I (C=O) peak, implying that muscle proteins transition from α-helix to β-sheet-rich structures. Hence, muscle contraction can be characterized by a loss of order in the muscle-protein complex, accompanied by a destructuring of hydration water. The findings shed fresh light on the molecular mechanism of muscle contraction and motor protein dynamics.