The Experts below are selected from a list of 18717 Experts worldwide ranked by ideXlab platform
Andrew G Webb - One of the best experts on this subject based on the ideXlab platform.
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design of small volume hx and triple Resonance Probes for improved limits of detection in protein nmr experiments
2003Co-Authors: Timothy M Logan, Arthur S Edison, Andrew G WebbAbstract:Abstract Three- and four-frequency nuclear magnetic-Resonance Probes have been designed for the study of small amounts of protein. Both “HX” (1H, X, and 2H channels) and “triple-Resonance” (1H, 15N, 13C, and 2H) Probes were implemented using a single transmit/receive coil and multiple-frequency impedance matching circuits. The coil used was a six-turn solenoid with an observe volume of 15 μl. A variable pitch design was used to improve the B1 homogeneity of the coil. Two-dimensional HSQC spectra of ∼1 mM single labeled 15N- and double labeled 15N/13C-proteins were acquired in experimental times of approximately 2 h. Triple-Resonance capability of the small-volume triple-Resonance probe was demonstrated by acquiring three-dimensional HNCO spectra from the same protein samples. In addition to enabling very small quantities of protein to be used, the extremely short pulse widths (1H=4, 15N=4, and 13C=2 μs) of this particular design result in low power decoupling and wide-bandwidth coverage, an important factor for the ever-higher operating frequencies used for protein NMR studies.
Thomas J Meade - One of the best experts on this subject based on the ideXlab platform.
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analytical methods for characterizing magnetic Resonance Probes
2012Co-Authors: Lisa M Manus, Renee C Strauch, Andy H Hung, Amanda L Eckermann, Thomas J MeadeAbstract:The efficiency of Gd(III) contrast agents in magnetic Resonance image enhancement is governed by a set of tunable structural parameters. Understanding and measuring these parameters requires specific analytical techniques. This Feature describes strategies to optimize each of the critical Gd(III) relaxation parameters for molecular imaging applications and the methods employed for their evaluation.
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a modular system for the synthesis of multiplexed magnetic Resonance Probes
2011Co-Authors: Daniel J Mastarone, Amanda L Eckermann, Victoria S R Harrison, Giacomo Parigi, Claudio Luchinat, Thomas J MeadeAbstract:We have developed a modular architecture for preparing high-relaxivity multiplexed Probes utilizing click chemistry. Our system incorporates azide bearing Gd(III) chelates and a trialkyne scaffold with a functional group for subsequent modification. In optimizing the relaxivity of this new complex, we undertook a study of the linker length between a chelate and the scaffold to determine its effect on relaxivity. The results show a strong dependence on flexibility between the individual chelates and the scaffold with decreasing linker length leading to significant increases in relaxivity. Nuclear magnetic Resonance dispersion (NMRD) spectra were obtained to confirm a 10-fold increase in the rotational correlation time from 0.049 to 0.60 ns at 310 K. We have additionally obtained a crystal structure demonstrating that modification with an azide does not impact the coordination of the lanthanide. The resulting multinuclear center has a 500% increase in per Gd (or ionic) relaxivity at 1.41 T versus small mole...
Sylvia Pietri - One of the best experts on this subject based on the ideXlab platform.
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investigation of subcellular acidic compartments using α aminophosphonate 31p nuclear magnetic Resonance Probes
2008Co-Authors: Gaelle Gosset, Michel Satre, Bruno Blaive, Jeanlouis Clement, Jeanbaptiste Martin, Marcel Culcasi, Sylvia PietriAbstract:The 31P nuclear magnetic Resonance (NMR) characteristics, toxicity, and cellular penetration of five linear or cyclic alpha-aminophosphonate highly sensitive pH Probes were investigated in Dictyostelium discoideum cells and isolated rat hearts and were compared with three phosphonic acid derivatives. The line width broadening at pH approximately pK(a), which was satisfactorily modelized for all compounds, was significantly limited in biological milieu for the new markers, affording a four- to sixfold better accuracy in pH determination. Cellular uptake or washout of nontoxic concentrations (< 15 mM) of alpha-aminophosphonates occurred by rapid passive permeation, whereas standard Probes required a much slower fluid-phase pinocytosis and transport processes that could ultimately lead to trapping. Using mild concentrations (< 4 mM) three alpha-aminophosphonates having 6 < pK(a) < 7 allowed an easy and simultaneous 31P NMR determination of cytosolic, acidic, and extracellular compartments in anoxic-reoxygenated or starving D. discoideum.
Abi B. - One of the best experts on this subject based on the ideXlab platform.
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Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
2021Co-Authors: Abi B., Albahri T., Al-kilani S., Allspach D., Alonzi L.  , Anastasi A., Anisenkov A., Azfar F., Badgley K.Abstract:We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly a\u3bc 61(g\u3bc 122)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency \u3c9a between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic Resonance Probes calibrated in terms of the equivalent proton spin precession frequency \u3c9~\u2032p in a spherical water sample at 34.7 18C. The ratio \u3c9a/\u3c9~\u2032p, together with known fundamental constants, determines a\u3bc(FNAL)=116592040(54) 710 1211 (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both \u3bc+ and \u3bc 12, the new experimental average of a\u3bc(Exp)=116592061(41) 710 1211 (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviation
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Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46\ua0ppm
2021Co-Authors: Abi B., Albahri T., Al-kilani S., Allspach D., Anastasi A., Anisenkov A., Azfar F., Badgley K., Alonzi L. \u2009p., Bae Fler S.Abstract:We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly a\u3bc 61(g\u3bc 122)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency \u3c9a between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic Resonance Probes calibrated in terms of the equivalent proton spin precession frequency \u3c9~\u2032p in a spherical water sample at 34.7 18C. The ratio \u3c9a/\u3c9~\u2032p, together with known fundamental constants, determines a\u3bc(FNAL)=116592040(54) 710 1211 (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both \u3bc+ and \u3bc 12, the new experimental average of a\u3bc(Exp)=116592061(41) 710 1211 (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviation
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Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
2021Co-Authors: Abi B., Albahri T., Al-kilani S., Allspach D., Anastasi A., Anisenkov A., Azfar F., Badgley K., Alonzi L. P., Baeßler S.Abstract:We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_\mu \equiv (g_\mu-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $\omega_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic Resonance Probes calibrated in terms of the equivalent proton spin precession frequency ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both $\mu^+$ and $\mu^-$, the new experimental average of $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviationsComment: 10 pages; 4 figure
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Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm.
2021Co-Authors: Abi B., Albahri T., Al-kilani S., Allspach D., Anastasi A., Anisenkov A., Azfar F., Badgley K., Lp Alonzi, Baeßler S.Abstract:We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic Resonance Probes calibrated in terms of the equivalent proton spin precession frequency ω[over ˜]_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ω[over ˜]_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations
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Measurement of the positive muon anomalous magnetic moment to 0.46 ppm
2021Co-Authors: Al-kilani S., Abi B., Albahri T., Azfar F., Henry SAbstract:We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g−2 Experiment for the positive muon magnetic anomaly aμ≡(gμ−2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ωa between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic Resonance Probes calibrated in terms of the equivalent proton spin precession frequency ˜ω′p in a spherical water sample at 34.7 °C. The ratio ωa/˜ω′p, together with known fundamental constants, determines aμ(FNAL)=116592040(54)×10−11 (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ+ and μ−, the new experimental average of aμ(Exp)=116592061(41)×10−11 (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.
Timothy M Logan - One of the best experts on this subject based on the ideXlab platform.
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design of small volume hx and triple Resonance Probes for improved limits of detection in protein nmr experiments
2003Co-Authors: Timothy M Logan, Arthur S Edison, Andrew G WebbAbstract:Abstract Three- and four-frequency nuclear magnetic-Resonance Probes have been designed for the study of small amounts of protein. Both “HX” (1H, X, and 2H channels) and “triple-Resonance” (1H, 15N, 13C, and 2H) Probes were implemented using a single transmit/receive coil and multiple-frequency impedance matching circuits. The coil used was a six-turn solenoid with an observe volume of 15 μl. A variable pitch design was used to improve the B1 homogeneity of the coil. Two-dimensional HSQC spectra of ∼1 mM single labeled 15N- and double labeled 15N/13C-proteins were acquired in experimental times of approximately 2 h. Triple-Resonance capability of the small-volume triple-Resonance probe was demonstrated by acquiring three-dimensional HNCO spectra from the same protein samples. In addition to enabling very small quantities of protein to be used, the extremely short pulse widths (1H=4, 15N=4, and 13C=2 μs) of this particular design result in low power decoupling and wide-bandwidth coverage, an important factor for the ever-higher operating frequencies used for protein NMR studies.