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. Deadtime in the ACERT 95 GHz pulse spectrometer is presently around 40 nanoseconds, which carries substantial impact on the system SNR, and therefore spin sensitivity. This limitation is significant when collecting data on biological samples of low concentration. Our estimate is that the spectrometer's present intrinsic deadtime can be reduced to 15 ns or less by a.) modifications to the Extended-Interaction klystron Amplifier (EIA) modulator and b.) reduction of the quasioptical bridge corrugated waveguide length. With regard to the latter contribution we note that the ringdown time of the present 900mm corrugated waveguide section is predicted to be ca 20ns, a figure that is in good agreement with our low power evaluation data. Installation of the Cryogenic, Ltd. 9T magnet to replace the present Oxford 6T magnet, scheduled for late August, will permit substituting a 300mm section for the present corrugated waveguide section, thereby reducing the waveguide length and ringdown time by a factor of 3. The resulting waveguide-related deadtime contribution in attaining the spectrometer receiver noise floor of approximately 1 nW from an initial level of 1KW will accordingly fall from 20ns to 6.7ns. Regarding the modulator timing, the modulator internal timing hardware was initially designed to operate for a fixed retriggerable interval of approximately 1 ?s to simplify the original external timing system configuration consisting of discrete timing modules. This """"""""triggerable"""""""" hardware option, however, has the unwanted side effect of introducing around 10ns r.m.s. modulator turn-off jitter, which contributes about 20ns of additional deadtime. The solution to this minimizing this deadtime contribution is straightforward. Our 95 GHz spectrometer timing system has been upgraded with a commercial multichannel programmable card and companion high-resolution (1ns) card of ACERT design. A suitably programmed timing control line, with our planned modulator internal logic modifications, will permit us to operate the EIA modulator in a """"""""strobed"""""""" mode, where the modulator turn-off time will then reflect the system's intrinsic resolution of 1ns and a deadtime improvement of about 20ns. We estimate that the two system improvements described in this Subproject will reduce the 95 GHz deadtime to ca 15ns, from the present value of ca 40ns.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR016292-11
Application #
8363995
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
$1,589
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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