The electron paramagnetic resonance signal of the cupric ion (its perpendicular component) at −196°C was found to be different in shape in human blood plasma and serum. On the addition of acid, substrate of ceruloplasmin, reducing agent, or denaturing agent, serum exhibited a complex electron paramagnetic resonance spectrum similar to that of a copper-diethyldithiocarbamate complex in an organic solvent, with a simultaneous disappearance of the cupric ion signal. Such an electron paramagnetic resonance spectrum occurred only from human serum but not from animal (guinea pig, mouse, rat, cattle, or monkey) serum.. PDF Article ...
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TY - JOUR. T1 - Kinetic and stoichiometric assessment of the antioxidant activity of flavonoids by electron spin resonance spectroscopy. AU - McPhail, D B AU - Hartley, R C AU - Gardner, P T AU - Duthie, G G. PY - 2003/3/12. Y1 - 2003/3/12. N2 - dThere is current interest in the use of naturally occurring flavonoids as antioxidants for the preservation of foods and the prevention of diseases such as atherosclerosis and cancers. To establish the molecular characteristics required for maximum antioxidant activity, electron spin resonance (ESR) spectroscopy has been used to determine the stoichiometry and kinetics of the hydrogen-donating ability of 15 flavonoids and D-alpha-tocopherol to galvinoxyl, a resonance-stabilized, sterically protected aryloxyl radical. The second-order reaction rates, which will be governed by O-H bond dissociation energies, were myricetin , morin , quercetin , fisetin similar to catechin , kaempferol similar to luteolin , rutin , D-alpha-tocopherol , taxifolin , ...
In atomic physics, hyperfine structure refers to small shifts and splittings in the energy levels of atoms, molecules, and ions, due to interaction between the state of the nucleus and the state of the electron clouds. In atoms, hyperfine structure arises from the energy of the nuclear magnetic dipole moment interacting with the magnetic field generated by the electrons and the energy of the nuclear electric quadrupole moment in the electric field gradient due to the distribution of charge within the atom. Molecular hyperfine structure is generally dominated by these two effects, but also includes the energy associated with the interaction between the magnetic moments associated with different magnetic nuclei in a molecule, as well as between the nuclear magnetic moments and the magnetic field generated by the rotation of the molecule. Hyperfine structure contrasts with fine structure, which results from the interaction between the magnetic moments associated with electron spin and the ...
As the silicon technology approaches to its physical limit, the future electronic devices will depend on behaviors of a few electrons. This study is to exp
Synthetically useful hydrocarbon oxidations are catalysed by bio-inspired non-heme iron complexes using hydrogen peroxide as oxidant, and carboxylic acid addition enhances their selectivity and catalytic efficiency. Talsi has identified a low-intensity g = 2.7 electron paramagnetic resonance signal in such catalytic systems and attributed it to an oxoiron(V)-carboxylate oxidant. Herein we report the use of Fe-II(TPA(star)) (TPA(star) = tris (3,5-dimethyl-4-methoxypyridyl-2-methyl)amine) to generate this intermediate in 50% yield, and have characterized it by ultraviolet-visible, resonance Raman, Mossbauer and electrospray ionization mass spectrometric methods as a low-spin acylperoxoiron(III) species. Kinetic studies show that this intermediate is not itself the oxidant but decays via a unimolecular rate-determining step to unmask a powerful oxidant. The latter is shown by density functional theory calculations to be an oxoiron(V) species that oxidises substrate without a barrier. This study ...
The magnetic and electronic properties of heavily doped n-type 6H SiC samples with a nitrogen concentration of 10{sup 19} and 4 × 10{sup 19 }cm{sup −3} were studied with electron spin resonance (ESR) at 5-150 K. The observed ESR line with a Dysonian lineshape was attributed to the conduction electrons (CE). The CE ESR (CESR) line was fitted by Lorentzian (insulating phase) (T , 40 K) and by Dysonian lineshape (metallic phase) above 40 K, demonstrating that Mott insulator-metal (IM) transition takes place at ∼40 K, accompanied by significant change in the microwave conductivity. The temperature dependence of CESR linewidth follows the linear Korringa law below 40 K, caused by the coupling of the localized electrons (LE) and CE, and is described by the exponential law above 40 K related to the direct relaxation of the LE magnetic moments via excited levels driven by the exchange interaction of LE with CE. The g-factor of the CESR line (g{sub ‖} = 2.0047(3), g{sub ⊥} = 2.0034(3)) is ...
Cytotoxic effects of daunomycin were investigated upon differentiation of Friend erythroleukemia cells induced with hexamethylene bisacetamide, a process during which a 20-fold increase in the hemoglobin content occurred. Daunomycin proved to be more toxic to differentiated Friend cells than to their undifferentiated counterparts. No changes in the daunomycin uptake rates of the two cell types were detectable. Externally added catalase and desferrioxamine mesylate protected against the additional cytotoxicity of daunomycin in differentiated cells, pointing to hydrogen peroxide and iron ions as mediators of the toxic effect. Daunomycin-dependent, cyanide-insensitive oxygen consumption of control and induced cells did not differ significantly, and the rate of formation of the daunomycin semiquinone radical electron paramagnetic resonance signal was similar in both cell types, indicating that the difference in toxicity was not due to increased drug activation by plasma membrane enzymes. ...
Nitric oxide (NO) production in the regenerating liver was estimated from the intensity of the electron paramagnetic resonance signal of the mononitrosyl complexes of iron and diethylthiocarbamate (DETC). Preformed complexes of intracellular non-heme Fe2+ and added DETC served as a trap for endogeneously produced NO. The data revealed dynamic changes of NO production temporally connected with the time periodicity of the liver regeneration. The first increase of NO production occurred ca. 1 h after partial hepatectomy (PHE) coinciding with the rapid response of the liver to injury. The second more pronounced production of NO was observed about 6 h after PHE, when the hepa-tocytes entered the first cell cycle, and originated mainly from them. The following minimum of NO synthesis coincided with the maximal rate of DNA synthesis. The third gradual rise of NO production was seen at the end of the investigated period, covering G2+M phases and the transit from the first to the second cell cycle of the ...
en] The C-phenyl-N-tert-butylnitrone/azobisisobutyronitrile pair is able to impart control to the radical polymerization of n-butyl acrylate as long as a two-step process is implemented, that is, the prereaction of the nitrone and the initiator in toluene at 85 degrees C for 4 h followed by the addition and polymerization of n-butyl acrylate at 110 degrees C. The structure of the in situ formed nitroxide has been established from kinetic and electron spin resonance data. The key parameters (the dissociation rate constant, combination rate constant, and equilibrium constant) that govern the process have been evaluated. The equilibrium constant between the dormant and active species is close to 1.6 x 10(-12) mol L-1 at 110 degrees C. The dissociation rate constant and the activation energy for the C-ON bond homolysis are 1.9 x 10(-3) s(-1) and 122 +/- 15 kJ mol(-1), respectively. The rate constant of recombination between the propagating adical and the nitroxide is as high as 1.2 x 10(9) L mol(-1) ...
With more than 940,000 new colorectal cancer cases worldwide each year, there is no better way for colorectal cancer routine screening. The aim of this study was to investigate whether the fatty acid binding to albumin is detectably and significantly altered in colorectal cancer patients when compared with healthy people, in order to find a better way for colorectal cancer diagnosis. One hundred and forty-one patients operatively treated for colorectal cancer were included in the examination, and 180 healthy people were also enrolled as controls. Commercial 16-doxyl stearic acid was used as spin probe. Serum albumin was analyzed by electron paramagnetic resonance (EPR) with spin probe. Discriminant analysis was carried out using the measured EPR spectra by SPSS 20.0. Of the original grouped cases, 89.4% were correctly classified. Of the
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Preliminary Study on Electron Paramagnetic Resonance(EPR) Signal Properties of Mobile Phone Components for Dose Estimation in Radiation Accident - Radiation accident;Electron spin resonance;Electron paramagnetic resonance;Dosimetry;
The heterogeneous oxidation of some substituted phenols has been studied by means of electron spin resonance. Strong signals, observed during the oxidation of the phenols with a free para-position, are due to secondary radicals derived from C4-O linked dimeric and polymeric phenols (A) are not to substituted 4, 4-di-pheno-semiquinones (B). Special attention has been given to the oxidation of 2, 6-dimethylphenol which yields a radical with non-equivalent methyl groups. The e. s. r. spectra of the secondary radicals from some 4-substituted 2, 6-dimethylphenol are identical to each other and to that from 2, 6-dimethylphenol itself. This indicates that in these radicals the para-substituent had been displaced by an aryloxy group. The ease of this displacement can be determined by use of the flow technique. ...
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Get this from a library! Electron Paramagnetic Resonance of d Transition Metal Compounds.. [F E Mabbs; D Collison] -- Electron paramagnetic resonance (epr) spectroscopy is a sensitive and versatile method of studying paramagnets, which is finding increasing use in chemistry, biochemistry, earth and materials ...
Magnetic Resonance Imaging of Tumor Physiology. Characterizing tumors and related pathological conditions on a physiologic basis by noninvasive radiological techniques is a potentially useful capability for diagnosis as well as for devising appropriate cancer treatment approaches. Magnetic resonance imaging (MRI) is a commonly used clinical imaging procedure that provides images of soft tissue anatomy with excellent detail. Recent advances have made it possible to provide functional information such as brain function using functional MRI (fMRI) techniques. To obtain physiological information such as oxygen or tissue redox stats in pathological situations such as solid tumors or ischemic/hypoxic tissue, quantitatively and noninvasively, we are developing imaging techniques based on electron paramagnetic resonance (EPR). EPR is similar to nuclear magnetic resonance (NMR) in many ways. NMR probes nuclei such as 1H, 13C, and 31P, while EPR detects paramagnetic species. Paramagnetic species by ...
TY - JOUR. T1 - ENDOR study on the dynamic properties of the first stable paramagnetic center in γ-irradiated L-alanine crystrals. AU - Rakvin, Boris. AU - Maltar-Strmecki, N.. AU - Kattnig, Daniel. AU - Grampp, Günter. PY - 2010. Y1 - 2010. U2 - 10.1021/jp103883x. DO - 10.1021/jp103883x. M3 - Article. VL - 114. SP - 7500. EP - 7505. JO - The journal of physical chemistry (Washington, DC) / A. JF - The journal of physical chemistry (Washington, DC) / A. SN - 1089-5639. ER - ...
Four heteroleptic copper(I) complexes containing phenanthroline and monoanionic nido-carborane-diphosphine ligands have been prepared and structurally characterized by various spectroscopic techniques and X-ray diffraction. These complexes exhibit intense absorptions in the visible range and excited-state lifetimes on the microsecond scale. Their application in visible-light-induced cross-dehydrogenative coupling reactions was investigated. Preliminary studies showed that one of the four copper(I) complexes is an efficient catalyst for photoinduced oxidative C[BOND]H functionalization using oxygen as oxidant. Furthermore, α-functionalized tertiary amines were obtained in good-to-excellent yields by light irradiation (λ>420 nm) of a mixture of our CuI complex, tertiary amines, and a variety of nucleophiles (nitroalkane, acetone, or indoles) under aerobic conditions. Electron paramagnetic resonance measurements provided evidence for the formation of superoxide radical anions (O2−⋅) rather ...
In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy Nature Communications, Published online: 12 June 2017; doi:10.1038/ncomms15749 Comparing the ground-state hyperfine structure of antihydrogen to that of hydrogen will provide insights into CPT symmetry in nature. Here the authors report the most precise in-beam measurement of this quantity for hydrogen to demonstrate…
We combine inorganic synthesis, chemical biology and spectroscopy to relate the structures of metal centres to reactivity. Many of the systems we study are paramagnetic, and we use electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) to study paramagnetic metal centres and radical chemistry. We also use NMR extensively to characterise diamagnetic species produced by redox processes, and to study reaction products and kinetics in catalytic systems. These methods are supplemented by DFT calculations of molecular properties and spectroscopic parameters. ...
my name is Artemis. These days I study at University of Science and Technology in Cracow. Due to the fact that semester is almost over one of my tutors asked me to do a quick presentation about Ways of measuring hyperfine interactions. I would appreciate it a lot if anyone of you could help me with this subject by just by mentioning me the ways how to do it, as I need to write about 6 methods and I cant find even one. Please help me ...
The Robinson group specializes in using a variety of Electron Paramagnetic Resonance (EPR) techniques, including continuous wave and pulsed Saturation Recovery (pSR) and pulsed Electron-Electron Double Resonance (pELDOR) EPR at 2 and 10 GHz. The research areas of interest include: dynamics of B-form duplex DNA and protein-DNA binding (as part of the process of DNA recognition); protein-RNA interactions; the interaction of interfacial signaling proteins and membranes; and the organization of organic chromophores in polymer matrices. The group collaborates with Larry Dalton, J. Michael Schurr, and Michael Gelb (all UW Chemistry) as well as Snorri Sigurdsson (University of Iceland), and Albert Beth and Eric Hustedt (Vanderbilt University).. The Robinson laboratory contains a CW/pulsed 10 GHz and a CW/pulsed 2 GHz EPR spectrometers. In addition, the Robinson group is responsible for the shared EPR instrumentation (from NIH-IEHS), which is used by more than a dozen groups around the UW campus. The ...
Nitric oxide (NO) has been used as a substrate analog to explore the structural and electronic determinants of enzymatic superoxide reduction at the mononuclear iron active site of Pyrococcus furiosus superoxide reductase (SOR) through the use of EPR, resonance Raman, Fourier transform IR, UV-visible absorption, and variable-temperature variable-field magnetic CD spectroscopies. The NO adduct of reduced SOR is shown to have a near-axial S = 3/2 ground state with E/D = 0.06 and D = 12 ± 2 cm-1 (where D and E are the axial and rhombic zero-field splitting parameters, respectively) and the UV-visible absorption and magnetic CD spectra are dominated by an out-of-plane NO-(π*)-to-Fe3+(dπ) charge-transfer transition, polarized along the zero-field splitting axis. Resonance Raman studies indicate that the NO adduct is six-coordinate with NO ligated in a bent conformation trans to the cysteinyl S, as evidenced by the identification of v(N-O) at 1,721 cm-1, v(Fe-NO) at 475 cm-1, and v(Fe-S(Cys), at
As noted in the Introduction, the role of NO in epileptogenesis is unclear. NO has been suggested to be both an anticonvulsant and a proconvulsant in animals (9, 10, 12-16). These inconsistencies may be due to the fact that although these studies measured the effects of NOS inhibitors, they did not actually measure NO production. The advantage of the current L-band EPR study is that we can make direct NO measurements by detecting it as the (DETC)2-Fe-NO complex in the brain of living mice. We were able to confirm that NO levels are elevated in tonic and clonic convulsions.. Both the in vivo and ex vivo EPR measurements confirmed that more NO was produced in the tonic than in the clonic convulsions, perhaps indicating that NO levels were proportional to the intensity of the convulsion. These results suggest that NO works as a proconvulsant. However, in the presence of NOS inhibitors, both L-NNA and 3Br-7NI suppressed the transition from clonic to tonic convulsion at high PTZ doses, while the ...
Dynamic nuclear polarization (DNP)[1][2][3] results from transferring spin polarization from electrons to nuclei, thereby aligning the nuclear spins to the extent that electron spins are aligned. Note that the alignment of electron spins at a given magnetic field and temperature is described by the Boltzmann distribution under the thermal equilibrium. It is also possible that those electrons are aligned to a higher degree of order by other preparations of electron spin order such as: chemical reactions (leading to Chemical-Induced DNP, CIDNP), optical pumping and spin injection. DNP is considered one of several techniques for hyperpolarization. DNP can also be induced using unpaired electrons produced by radiation damage in solids.[4][5] When electron spin polarization deviates from its thermal equilibrium value, polarization transfers between electrons and nuclei can occur spontaneously through electron-nuclear cross relaxation and/or spin-state mixing among electrons and nuclei. For example, ...
Electron paramagnetic resonance (EPR) spectroscopy is an unambiguous method to measure free radicals. The use of selective spin probes...
Chemistry Assignment Help, Transition metals - ligand field theory, The five d orbitals with distinct values of the magnetic quantum number (m) have the similar energy in a free atom or ion. In any compound they interact differently with the surrounding ligands and a ligand field splitting is performed. The c
Site-directed spin labeling (SDSL) in combination with electron paramagnetic resonance (EPR) spectroscopy is a rapidly expanding powerful biophysical technique to study the structural and dynamic properties of membrane proteins in a native environment. Membrane proteins are responsible for performing important functions in a wide variety of complicated biological systems that are responsible for the survival of living organisms. In this review, a brief introduction of the most popular SDSL EPR techniques and illustrations of recent applications for studying pertinent structural and dynamic properties on membrane proteins will be discussed ...
The same unpaired or odd electron that renders most radical intermediates unstable and highly reactive may be induced to leave a characteristic "calling card" by a magnetic resonance phenomenon called "electron spin resonance" (esr) or "electron paramagnetic resonance" (epr). Just as a proton (spin = 1/2) will occupy one of two energy states in a strong external magnetic field, giving rise to nmr spectroscopy; an electron (spin = 1/2) may also assume two energy states in an external field. Because the magnetic moment of an electron is roughly a thousand times larger than that of a proton, the energy difference between the spin states falls in the microwave region of the spectrum (assuming a moderate magnetic field strength). The lifetime of electron spin states is much shorter than nuclear spin states, so esr absorptions are much broader than nmr signals. One way of improving the signal to noise ratio in esr spectra is to display them as first derivatives rather than absorptions. These displays ...
A magnetic resonance imaging method for generating separate fat and water images of at least one slice utilizes a plurality of sequences acting on the slice in the presence of a steady magnetic field, each sequence including at least one first RF pulse, followed by a phase encoding gradient during which the spin resonance signal formed in the slice is detected, groups of sequences being formed with a position in time of the measuring gradient and/or a further RF pulse, if any, which differs from one group to another, the number of sequences per slice being twice as large as necessary for the formation of a similar image without fat/water separation. The phase encoding gradient is varied in steps from one sequence to another. The separate fat and water images (F,W) are formed from the resultant spin resonance signals by 2D Fourier transformation.
A physical picture of the origin of the zero field splittings and levels of the three zero field spin states of aromatic molecules is given. At very low temperatures (<2K), the spin-lattice relaxation processes between these levels can be frozen. Under these conditions, the emission properties of the lowest triplet state are the sum, rather than the population-weighed average, of those of the different emitting zero field levels. Since the rates of pumping and deactivating the different zero field levels of the lowest triplet states are most likely to be unequal, the steady-state population of these three levels becomes unequal, i.e., a state of spin alignment in one molecular direction can be produced. A number of phosphorescence-microwave multiple resonance experiments can thus be carried out from which important information can be determined. (Author)(*PHOSPHORESCENCE
PhD Project - (BBSRC DTP) Electron Paramagnetic Resonance Pulsed Dipolar Spectroscopy for Structural Biology at The University of Manchester, listed on FindAPhD.com
Pratt used an X-ray-scattering technique to examine the shape taken by each of these different SOD1 proteins. While wild-type SOD1 assembles into an unusually stable dimer (Perry et al., 2010), the mutants assumed flexible, unstable structures (see image at right). They also formed aggregates faster than wild-type SOD1, though all proteins formed snake-like fibrils if given sufficient time. "There is a striking agreement between severity of clinical outcome and the propensity to destabilize and aggregate," Tainer said.. SOD1 dimers normally contain two copper ions, each held in place by four amino acids. To examine how the different disease mutations influenced that part of the structure, the authors used electron spin resonance spectroscopy to measure the distance between those two coppers in three of the SOD1 mutants: G93A, G93D, and G93R. One or zero coppers in a dimer would not produce a signal. They observed that the mutants contained copper when they were first purified, but tended to lose ...
A. M. Prakash and Larry Kevan, Coordination Chemistry of Titanium in Titanosilicate Molecular Sieves Studied by Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopy In Proceedings of the 12th Interna tional Zeolite Conferences, Vol. IV;Treacy, M. M.J.; Marcus, B. K; Bisher, M. E., Higgins, J. B., Eds; Materials Research Society: Warrendale, Penn., 1999; pp 2825 - 2832 ...
... - reflects the multidimensional character of chemical biology, focusing in particular on the fundamental science of biological structures and systems, the use of chemical and biological techniques to elucidate
A chemist by background, McPhail has developed a range of techniques (using electron spin resonance spectroscopy), to determine the antioxidant potency of foodstuffs such as wine, tea, berry juices and even whiskies. "Although there has been a great deal of interest in identifying dietary sources high in antioxidants, it was understanding the complex relationships between molecular structure, antioxidant activity and bio-potency which really intrigued me," McPhail says. "By understanding these effects, the logical next step was to design new synthetic molecules that combine antioxidant potency along with the additional molecular features needed to produce drug-like characteristics. Developing a successful therapeutic is not just about a molecules ability to destroy free radicals; it is dependent on many factors, including stability, accessing the disease site and the ability to be absorbed by the cell and target key locations, such as the mitochondria, where oxidative stress occurs." It is this ...
The optical spectrum of any given atom is a result of the interplay between light and the electrons within the atomic shell. Ultra-precise measurements can even reveal the effects of the internal structure of the atomic nucleus, which are referred to as the "hyperfine structure". When measuring the hyperfine structure of highly-charged ions with few remaining electrons, researchers at TU Darmstadt found a discrepancy between the theoretically predicted and experimentally determined splittings: these empirically observed discrepancies were referred to as the "hyperfine puzzle", and raised the question as to whether the interplay between the few electrons bound to the atomic nucleus and the nucleus itself, under the influence of the prevailing enormously strong magnetic fields, is fully understood. The next step towards solving the puzzle was to re-determine the strength of the magnetic field within the atomic nucleus: theoretical predictions are strongly dependent on this parameter, which must be ...
Other articles where Spectral line is discussed: spectroscopy: Basic properties of atoms: …discrete wavelengths are sometimes called spectral lines.
In a newly published study, university researchers propose a new way to probe Earths deep interior that relies on a fifth force of nature called a long-range spin-spin interaction.. Researchers from Amherst College and The University of Texas at Austin have described a new technique that might one day reveal in higher detail than ever before the composition and characteristics of the deep Earth.. Theres just one catch: The technique relies on a fifth force of nature (in addition to gravity, the weak and strong nuclear forces and electromagnetism) that has not yet been detected, but which some particle physicists think might exist. Physicists call this type of force a long-range spin-spin interaction. If it does exist, this exotic new force would connect matter at Earths surface with matter hundreds or even thousands of kilometers below, deep in Earths mantle. In other words, the building blocks of atoms-electrons, protons, and neutrons-separated over vast distances would "feel" each others ...
Hyperpolarization by dissolution dynamic nuclear polarization (DNP) is a versatile technique to dramatically enhance the nuclear magnetic resonance (NMR) signal intensity of insensitive long-T1 nuclear spins such as 6 Li. The 6 Li longitudinal relaxation of lithium ions in aqueous solutions strongly depends on the concentration of paramagnetic species, even if they are present in minute amounts. We herein demonstrate that blood oxygenation can be readily detected by taking advantage of the 6 Li signal enhancement provided by dissolution DNP, together with the more than 10% decrease in 6 Li longitudinal relaxation as a consequence of the presence of paramagnetic deoxyhemoglobin.. Keywords: CIBM-AIT. ...
The search for large clusters of paramagnetic transition metal ions has been greatly stimulated by the discovery of single-molecule magnetism (Sessoli et al. 1993a,b; Christou et al. 2000). This is the superparamagnetic-like behaviour of molecular species that combine a large spin groundstate, S, with a relatively large and negative easy-axis-type magnetoanisotropy (as reflected in a large and negative zero-field splitting parameter, D; Christou et al. 2000). This results in the experimental observation of both hysteresis in magnetization versus DC magnetic field sweeps, and frequency-dependent out-of-phase AC magnetic susceptibility signals. Such a combination of large S and D values leads to a significant barrier (U) to magnetization reversal, whose maximum value is given by S2,D, or (S2−1/4),D, for integer and half-integer spins, respectively. SMMs thus represent a molecular or bottom-up approach to nanoscale magnetism, and they are consequently also called molecular nanomagnets. In ...
A method for processing a signal characteristic of cardiac activity in the atrium (A) and/or ventricle (V) of a heart (H) and for evaluating this signal with a view to obtaining a control signal for a cardiac pacemaker and/or defibrillator (3) can be carried out by: receiving a time dependent signal from at least one intracardial signal sensor (1, 2) in the atrium and/or ventricle; feeding the signal picked up by each signal sensor (1, 2) to a read and evaluation circuit (6) with a threshold characteristic; comparing the signals with a detection threshold; evaluating the result of the comparison to obtain an indication as to the presence of normal sinus-type cardiac activity or fibrillations; and producing the control signal, which characterizes the comparison result. The signal from the at least one sensor (1, 2) is fed to a first input stage (8, 11) which has a first adjustable detection threshold (TS(A), TS(V) that is constant in time and to a second input stage (9, 10) which has a second adjustable
in Bi i has been completely analyzed by means of a Fourier-transform spectrometer. From the intensity calculations it is seen that only 9 components of the possible 10 can be observed. The A and B constants are also calculated and compared with earlier results. The values of the levels 7s 2P3/2 and ...
Experimental deviations from Lorentzian line shape of collisional broadened pure rotational $CO (J=1\leftarrow 0, J=5\leftarrow 4)$ molecular lines have been observed. The deviations are effects of narrowing and asymmetry in the spectral line core. Measurements were performed by a RAD (radio-spectrometer with acoustic detector) spectrometer with a signal-to-noise ratio $\sim 1000$. While the fit error of the line profile to Lorentzian shape was within 0.5%, an error of line broadening parameters exceeded 4% for different shape models and lengths of line record. Picketts $model^{a}$ gave a much better residue between experimental and fitted data for CO lines, but the broadening parameter was more dependable on gas pressure and also had dependence on the length of line record. To clear up an origin of deviation from Lorentzian profile, either it is due to speed-dependent like effects or apparatus ones, accurate testings of receiving part of spectrometer was performed by using a resonance curve of ...
An Introduction to Transition - Metal Chemistry Ligand - Field Theory by Orgel, Leslie E. and a great selection of similar Used, New and Collectible Books available now at AbeBooks.com.
This book explains the foundations of pulse EPR, a field of spectroscopy which has now come of age and has found widespread application in investigations of structure, dynamics, and function of biological systems and synthetic materials.
A self-consistent charge analysis has been performed on the ESR spin-Hamiltonian parameters of CrO43- and MoO43- in which values of the spin-orbit constant and 〈 r〉-3for different charges on the ion...
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A series of structurally characterised mu-cyanodicopper(II) cryptates shows moderately strong antiferromagnetic interaction in the range -2J= 150-200 cm(-1), at the high end of the observed range for such assemblies. The lowest magnetic exchange coupling parameter is displayed where there is slight bending of the M-CN-M assembly, enforced by the constraints of cryptate encapsulation. Thermally accessible triplet EPR spectra are observed with zero-field splittings of the order of 0.13-0.14 cm(-1), confirming collinear ground-state dz2 orbitals for Cu(II), consistent with their trigonal-bipyramidal coordination geometries.