ELDOR

ELDOR is tlie acronym for electron-electron double resonance. In an ELDOR experiment [28] one observes a rednction in the EPR signal intensity of one hyperfme transition that results from the saturation of another EPR transition within the spin system. ELDOR measurements are still relatively rare bnt the experiment is fimily established in the EPR repertoire. 

With help of the four-level diagram of the =I= system (see figure BL15.8 two conniion ways for recording ELDOR spectra will be illnstrated. In freqnency-swept ELDOR the magnetic field is set at a value that satisfies the resonance condition for one of the two EPR transitions, e.g. 4<- 2, at the fixed observe klystron frequency, The pump klystron is then turned on and its frequency, is swept. When the pump... 

To analyse ELDOR responses, the reduction of the observed EPR transition at is expressed quantitatively in temis of the ELDOR reduction factor... 

ELDOR has been employed to study a number of systems such as inorganic compounds, organic compounds, biologically important compounds and glasses. The potential of ELDOR for studying slow molecular motions has been recognized by Freed and coworkers [29, 30]. 

Bruno G and Freed J 1974 ESR llneshapes and saturation In the slow motional region ELDOR Chem. Phys. Lett, pp 328-32... 

As discussed in Chapter 6, in systems with more than one unpaired electron the ESR spectrum contains features that involve electron-electron coupling parameters analogous to the nuclear hyperfine parameters. In those types of samples the advantages of double resonance are carried out by employing the use of two different microwave frequencies, one fixed and saturating, and one variable frequency that searches for transitions. This technique is known as ELDOR (electron-electron double resonance).38,40,41,44 It has been used much less than ENDOR and usually requires custom-built equipment. 

M. Bennati, A. Weber, J. Antonie, D.L. Perlstein, J. Robblee and J. Stubbe, Pulsed ELDOR spectroscopy measures the distance between the two tyrosyl radicals in the R2 subunit of the E. coli ribonucleotide reductase, J. Am. Chem. Soc., 2003, 125, 14988. 

H. Mino and T. Ono, Applications of pulsed ELDOR-detected NMR measurements to studies of photosystem II Magnetic characterization of Yd tyrosine radical and Mn2+ bound to the high-affinity site, Appl. Magn. Reson., 2003, 23, 571. 

B.R. Patyal, R.H. Crepeau, D. Gamliel and J.H. Freed, Two-dimensional Fourier transform ESR in the slow-motional and rigid limits 2D-ELDOR, Chem. Phys. Lett., 1990, 175, 453. 

Double-resonance spectroscopy involves the use of two different sources of radiation. In the context of EPR, these usually are a microwave and a radiowave or (less common) a microwave and another microwave. The two combinations were originally called ENDOR (electron nuclear double resonance) and ELDOR (electron electron double resonance), but the development of many variations on this theme has led to a wide spectrum of derived techniques and associated acronyms, such as ESEEM (electron spin echo envelope modulation), which is a pulsed variant of ENDOR, or DEER (double electron electron spin resonance), which is a pulsed variant of ELDOR. The basic principle involves the saturation (partially or wholly) of an EPR absorption and the subsequent transfer of spin energy to a different absorption by means of the second radiation, leading to the detection of the difference signal. The requirement of saturability implies operation at close to liquid helium, or even lower, temperatures, which, combined with long experimentation times, produces a... 

Raz, I., Eldor, R., and Naparstek, Y., Immune modulation for prevention of type I diabetes mellitus, Trends Biotechnol., 23, 128, 2005. 

Levenberg S, Huang NF, Lavik E, Rogers AB, Itskovitz-Eldor J, Langer R (2003) Differentiation of human embryonic stem cells on three-dimensional polymer scaffolds. Proc Natl Acad Sci USA 100 12741-12746. 

Elba reaction org chem The formation of anthracene derivatives by dehydration and cycllzation of diaryl ketone compounds which have a methyl group or methylene group heating to an elevated temperature is usually required. elbs re.ak shan ( ELDOR See electron electron double resonance. ( el,dor or e el de o ar ( electrical calorimeter analy chem Device to measure heat evolved (from fusion or vaporization, for example) measured quantities of heat are added electrically to the sample, and the temperature rise is noted. a lek tra kal kal a rlm ad ar)... 

Thomson JA, Itskovitz-Eldor J, Shapiro SS, Waknitz MA, Swiergiel JJ, Marshall VS, Jones JM. Embryonic stem cell lines derived from human blastocysts. Science 1998 282 1145-1147. 

Itskovitz-Eldor J, Schuldiner M, Karsenti D, Eden A, Yanuka O, Amit M, Soreq H, Benvenisty N. Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers. Mo/MeJ 2000 6 88-95. 

Gerecht-Nir, S., and J. Itskovitz-Eldor. The Promise of Human Embryonic Stem Cells. Best Practice Research Clinical Obstetrics Gynaecology 18 no. 6 (2004) 843-852. 

The ENDOR technique refers to electron-nuclear double resonance. This consists of the effect on a partially saturated ESR line of simultaneously irradiating the sample with a radiofrequency to induce nuclear resonance transitions of hyperfine coupled nuclei. It may enable one to obtain information about signs of coupling constants. ELDOR is the technique corresponding to electron-electron double resonance. Such techniques, coupled with TRIPLE resonance, have been utilized and well described in a discussion of pyridine and 4,4-bipyridyl radical anion ESR spectra measured in sodium/liquid ammonia (80JMR<41)17). 

Kehat, I., D. Kenyagin-Karsenti, M. Snir, H. Segev, M. Amit, A. Gepstein, E. Livne, O. Binah, J. Itskovitz-Eldor, and L. Gepstein, Human embryonic stem cells can differentiate into myocytes with structural and functional properties of cardiomyocytes. J Clin Invest, 2001.108(3) 407-14. 

Dorso CR, Levin RI, Eldor A, Jaffe EA, Weksler BB. Chinese food and platelet. N Engl J Med 1980 303 756-757. 

ESEEM experiments on Yp.398,399 Mino and Ono400,401 used a new technique, ELDOR-detected NMR, to measure the hyperfine structure of Yp in PS II. Except for slightly higher linewidths the spectrum was found to correspond with the one from pulse ENDOR. 

The two centres are connected by a flexible linkage that does not have well defined secondary structure. Pulsed ELDOR experiments were performed at 4.2 K using a one-loop-one-gap resonator. The narrow Mo(V) signal was pulsed at... 

Thomson J.A, Itskovitz-Eldor J., Shapiro S.S., Waknitz M.A., Swiergiel J.J., Marshall... 

Thomson, J.A., Itskovitz-Eldor, J., Shapiro, S.S., Waknitz, M.A., Swiergiel, J.J., Marshall, V.S., Jones, J.M. (1998). Embryonic stem cell lines derived from human blastocysts. Science. 282, 1145-7. Erratum in (1998) Science, 282, 1827. 

Lightman A, Kol S, Itskovitz-Eldor J. A prospective randomized study comparing intramuscular with intravaginal natural progesterone in programmed thaw cycles. Hum Reprod 1999 14(10) 2596-9. 

Eldor R, Cohen IR, Raz I. Innovative immune-based therapeutic approaches for the treatment of type 1 diabetes mellitus. Int Rev Immunol. 2005 24 327-339. 

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