Electron Spin Resonance Equipment Research Articles

Determination of Spin Concentrations in ESR Tomography as Applied for the Spatial Distribution of Spin Labels in Human Skin

The spectral–spatial electron spin resonance (ESR) imaging experiment provides information about the spatial and spectral properties of the examined sample, as well as the intensity distribution. Obtaining quantitative statements of the respective sample requires the usage of reference standards such as diphenylpicrylhydrazyl (DPPH) or charcoal. By means of ultraviolet-visible spectroscopy a DPPH sample has been quantified to become the reference DPPH standard for the following experiments. Moreover, charcoal together with DPPH serves as a standard to determine the spatial dimension. An ESR tomographic device has been modified concerning the sample shaping and arranging in a TE102 resonator to allow the spatially resolved quantitative determination of spin concentrations of spin probes (S = 1/2) with an acceptable error. Only standard ESR equipment has been used except the additional gradient coils and their computer-aided controls for recording the tomogram. The presented results, i.e., the spatially resolved determination of spin concentrations, seem to be useful to describe, e.g., transport processes in biological objects. As a first application of the developed method, the spatial resolution of the effect of ultraviolet irradiation on the concentration of a spin probe in human skin could be determined. Altogether, the newly introduced method widens the field of applications of ESR spectroscopy and tomography.

Three-Dimensional Observation of Composite Haldane Spin Chains in IPA-CuCl3 by Electron Spin Resonance Using a Two-Rotation-Axis Goniometer

Using a two-rotation-axis goniometer inserted into electron spin resonance equipment, for the first time, we successfully observed the three-dimensional distribution of the g -values of the composi...

Low microwave-amplitude ESR spectroscopy: Measuring spin-relaxation interactions of moderately immobilized spin labels in proteins

Electron spin resonance (ESR) spectroscopy in combination with site-directed spin labeling (SDSL) is a powerful tool for determining protein structure, dynamics and interactions. We report here a method for determining interactions between spin labels and paramagnetic relaxation agents, which is performed under subsaturating conditions. The low microwave-field amplitude employed ( h 1<0.36 G) only requires standard, commercially available ESR equipment. The effect of relaxation enhancement on the spin–spin-relaxation time, T 2e, is measured by this method, and compared to classical progressive power saturation performed on a free spin label, (1-oxyl-2,2,5,5-tetramethyl-Δ 3-pyrroline-3-methyl)methanethiosulfonate (MTSL), and a spin-labeled protein ( Thermomyces lanuginosa lipase, TLL-I252C), employing the water-soluble relaxation agent chromium(III) oxalate (Crox) in concentrations between 0–10 mM. The low-amplitude theory showed excellent agreement with that of classical power saturation in quantifying Crox-induced relaxation enhancement. Low-amplitude measurements were then performed using a standard resonator, with Crox, on 11 spin-labeled TLL mutants displaying rotational correlation times in the motional narrowing regime. All spin-labeled proteins exhibited significant changes in T 2e. We postulate that this novel method is especially suitable for studying moderately immobilized spin labels, such as those positioned at exposed sites in a protein. This method should prove useful for research groups with access to any ESR instrumentation.

A new spectrophotometric readout for the alanine-triphenyl tetrazolium chloride system for high-dose dosimetry

The electron spin resonance (ESR) readout of radical concentration in irradiated L -alanine is well known as a transfer dosimetry system, however, the high cost of the ESR equipment is a serious handicap for large-scale routine application. In this study the reaction between irradiated L -alanine powder and aqueous solution of triphenyl tetrazolium chloride (TTC) was studied. The radical produced by irradiation of alanine reacts during the dissolution with TTC forming pink-colored formazans with absorption maxima around 401 and 487 nm. This readout method can be used in the 2–200 kGy dose range.

Tunable Phase Transitions in Conductive Cu(2,5-Dimethyl-Dicyanoquinonediimine)$\mathsf{_2}$ Radical Ion Salts

The conduction process of the copper salts of DCNQI and the origin of the phase transition inducable in different ways, is explained in this review by an admixture of the copper d states to the DCNQI pπ band. This admixture depends on structural processes which shift the charge transfer δ from the copper moiety to the DCNQI stack to larger values with reduced lattice dimensions. Reaching exactly δ = 4/3 (band filling degree ρ = 2/3), the trimerization in the copper stack leads to the disproportion of the mixed valence state of Cu by the localization of the d states as Cu 2+ . A charge density wave is formed, opening a gap at the Fermi level E F . These statements are acquired by selective deuteration, selective alloying, applying pressure and by simultaneous electron spin resonance (ESR) and conductivity experiments in the ESR equipment under pressure as a function of temperature. For all systems, when reaching critical values of the unit cell volume, phase transitions take place. We could establish a general phase diagram which is based on an effective pressure scale including internal (chemical) and external applied pressure.

バイオドシメトリ Ｖ． 電子スピン共鳴法（ＥＳＲ）によるバイオドシメトリ

バイオドシメトリ Ｖ． 電子スピン共鳴法（ＥＳＲ）によるバイオドシメトリ

Studies on myocardial metabolism in the ischemic heart. II. Studies by the electron spin resonance method

The intracellular oxydation reduction reaction is summed up to binding of hydrogen and oxygen into water through the electron transport system. ATP which is a key member of energy supplying agents is produced mainly by this electron transport system. From these facts it may be considered that significant changes of cardiac function will be induced by myocardial ischemia. The electron spin resonance (ESR) study has been used as a medical and biological technique which has been able to give us clues for clarifying the biochemical reaction mechanisms. The purpose of this paper is to examine the usefullness of ESR as an index of myocardial hypoxia. Method Twenty four adult mongrel dogs were used. The methods of production of myocardial ischemia and blood sampling study were almost same as described in Part I. Coronary artery and sinus blood were centrifuged (3000/min, 5 min) to separate plasma which was soon frozen by dipping the container into aceton dryice. Heart muscle was thrown into liquid nitrogen soon after cutting off. The frozen muscle was then powdered with liquid nitrogen in a mortar. The frozen powdered plasma or muscle was dried by the freezing desiccator. Suction period was about 1.5 hours in cases of the plasma sample, and 3 hours in cases of the muscle sample. The dried materials were packed into the special glass tube for ESR spectrometry, then weighed, and stored in a refrigerator at -20°C. JES-3BS-X type ESR spectrometer was used to obtain the ESR signal which was a differential curve of a free radical concentration curve. In this paper ESR intensity was calculated as follows : ESR intensity = the hight of signal from a material / the hight of signal from a standard substance. MnCl2 was used as a standard substance. Result and Discussion The intensity of ESR signal may be influenced by many factors, such as hemolysis, leaving period of materials at room temperature, suction duration of vacuum pump, and condition of ESR equipment. ESR signals in this experiment were stable within 0.2% of hemolytic percentage, within 60 minutes of leaving at room temperature, within 28 days of storage at -20°C. There were about 10% standard error of ESR intensities which were obtained from 6 samples of the same material and about 6 % standard error of ESR intensities which were obtained from 6 time estimation of the same sample. In normal condition coronary A-V difference of ESR intensity showed no significant tendency. ESR intensities of normal heart muscle (mean 1.011) were greater than that of normal plasma (mean 0.349). During ischemic condition coronary A-V difference of ESR intensity tended to release from the myocardium. From these data it is suggested that free radical concentration increases in the ischemic myocardium where there may be disturbance in the electron transport system. Although free radicals can appear in many biochemical reactions in the living cells, free radicals in this experiment can originate from the intramitochondrial electron transport system, especially from flavin enzymes, taking the bibliographical data into consideration. Some medica-ments were administered intravenously 30 minutes after the onset of ischemia. Coronary A-V difference of ESR intensity tended to increase of release after epirenamine hydrochloride injection, whereas it tended to decrease of release after dipyridamole or theophylline ethylenediamine injection. All these medicaments increase the coronary flow in some ways. It may be considered that ESR signals reflect mainly the relative smoothness of oxygenation of the myocardium. Summary 1, ESR intensities of normal heart muscle were greater than that of normal plasma. Greater ESR intensities were found in the ischemic muscle and plasma than that in normal muscle and plasma. [the rest omitted]