This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. High-level modulation of the B0 external magnetic field is desirable in millimeter-wave ESR studies over a wide range of problems in chemistry and biology where the linewidths are often large (100G) given that the signal to noise ratio (SNR) is proportional to the modulation amplitude (mod amp) for mod amps less than or approaching 1/5 of the line width. For high-level modulation of B0 in our 170 and 240 GHz spectrometer bridges, we have designed an extremely wideband power amplifier which is capable of stably driving off-tuned resonant loads which exhibit a large reactive component. Conventional audio-frequency power amplifiers, which are sometimes pressed into service as modulation coil drivers, are not well-suited for this type of service. Generally, they are inefficient and poorly characterized in the region above approximately 50 KHz, especially when driving highly capacitive or inductive impedances. The ACERT modulation amplifier design, in contrast, overcomes those limitations. It operates in either constant-current (CC) or constant-voltage (CV) modes, and can produce up to 50 watts of output power at frequencies from d.c. to 150KHz. Utilizing a commercially-available h.v. hybrid operational amplifier, this wideband power driver design is simple, low-cost and robust, but also features high linearity and stability. Its output section includes provisions for detection and signaling of abnormal output conditions, such as clipping due to, e.g., mistuning of the modulation coil network. Operation in CC mode minimizes amplitude drift in the detected spectrum due to modulation coil self-heating and permits direct modulation with a constant magnetic field generation coefficient, when a fixed input-to-field ratio is required. CV mode permits use of the amplifier in other laboratory applications such as piezoelectric actuator driver for CD-ESR. Having prototyped and tested sections of the modulation driver amplifier, our next step in the project plan is to design a compact package for the complete amplifier and construct several integrated units for HF, and possible CD-ESR use, during the coming year.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR016292-11
Application #
8363959
Study Section
Special Emphasis Panel (ZRG1-BCMB-K (40))
Project Start
2011-09-01
Project End
2012-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
11
Fiscal Year
2011
Total Cost
$482
Indirect Cost
Name
Cornell University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Jain, Rinku; Vanamee, Eva S; Dzikovski, Boris G et al. (2014) An iron-sulfur cluster in the polymerase domain of yeast DNA polymerase ?. J Mol Biol 426:301-8
Pratt, Ashley J; Shin, David S; Merz, Gregory E et al. (2014) Aggregation propensities of superoxide dismutase G93 hotspot mutants mirror ALS clinical phenotypes. Proc Natl Acad Sci U S A 111:E4568-76
Georgieva, Elka R; Borbat, Peter P; Ginter, Christopher et al. (2013) Conformational ensemble of the sodium-coupled aspartate transporter. Nat Struct Mol Biol 20:215-21
Airola, Michael V; Sukomon, Nattakan; Samanta, Dipanjan et al. (2013) HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors. PLoS Biol 11:e1001479
Airola, Michael V; Huh, Doowon; Sukomon, Nattakan et al. (2013) Architecture of the soluble receptor Aer2 indicates an in-line mechanism for PAS and HAMP domain signaling. J Mol Biol 425:886-901
Sun, Yan; Zhang, Ziwei; Grigoryants, Vladimir M et al. (2012) The internal dynamics of mini c TAR DNA probed by electron paramagnetic resonance of nitroxide spin-labels at the lower stem, the loop, and the bulge. Biochemistry 51:8530-41
Yu, Renyuan Pony; Darmon, Jonathan M; Hoyt, Jordan M et al. (2012) High-Activity Iron Catalysts for the Hydrogenation of Hindered, Unfunctionalized Alkenes. ACS Catal 2:1760-1764
Dzikovski, Boris; Tipikin, Dmitriy; Freed, Jack (2012) Conformational distributions and hydrogen bonding in gel and frozen lipid bilayers: a high frequency spin-label ESR study. J Phys Chem B 116:6694-706
Gaffney, Betty J; Bradshaw, Miles D; Frausto, Stephen D et al. (2012) Locating a lipid at the portal to the lipoxygenase active site. Biophys J 103:2134-44
Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey et al. (2012) Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies. J Am Chem Soc 134:9209-18

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