Thermoluminescent response of gamma irradiated Na^(+)–Cu^(+) ionexchanged silicate glass in large dose range

The introduction of metals into vitreous matrices is the origin of various interesting phenomena;in particular,the presence of copper ions in glass has been the subject of considerable research because of its numerous applications.The ion-exchange process is primarily used to introduce copper ions into glass matrices.The thermoluminescence(TL)of silicate glass was studied to evaluate its potential as gamma-sensitive material for dosimetric applications;the effect of copper doping on the thermoluminescent sensitivity was investigated using the Cu-Na ion-exchange technique for different concentrations and doping conditions,over a wide dose range of 10 mGy to 100 kGy.The results showed that Cu doping significantly improved the sensitivity of the glasses to gamma radiation.After the ion-exchange,two peaks appeared in the glow curves at approximately 175 and 230°C,respectively,which possibly originated from the Cu^(+) centers,along with a weak TL peak at around 320℃.We also attempted to explain the origin of the observed thermoluminescence by exploiting the Electron paramagnetic resonance(EPR)spectra.The results clearly show quenching of the TL emission with increasing copper concentrations.The present work indicates that the thermoluminescence response of these glasses to gamma rays can be reasonably measured in the range of 0.001-100 kGy.This study also facilitates the understanding of the basic TL mechanism in this glass system.

Correlations between trace elements in pyrite and gold mineralization of gold deposits on the North China platform

By studying both the microscopic physical and chemical typomorphic characteristics of typical mineral pyrite samples associated with representative gold deposits on the north-central margin of the North China Platform,this paper seeks to identify macroscopic metallogenic mechanisms of gold deposits and to reveal the formation mechanism of lattice gold in pyrite.Typomorphic characteristics of pyrite reveal that pyrite grain size has a negative correlation with gold content.Cubic pyrite,as the dominant crystal form,contains more gold than pentagonal dodecahedral pyrite.Both pyrite crystal forms and chemical compositions indicate that the replacement style of gold deposit formed in a low saturability,low sulfur fugacity,and at temperatures either much higher or much lower than its best forming temperature;comparatively,that of the quartz vein style of gold deposit occurred under conditions with the best temperature,rich in sulfur,and with high sulfur fugacity.The Au/Ag ratios of the pyrites show that both the replacement and quartz vein styles of deposits are mesothermal and hypothermal,while the Co/Ni ratios of the pyrites indicate that the quartz vein style is of magmatic-hydrothermal origin.The X-ray diffraction intensity of pyrite rich in gold is lower than that of pyrite poor in gold at the quartz vein style.In general,with an increase in gold content in pyrite,the total sum intensityΣI decreases.The pyroelectricity coefficient has a negative correlation trend with the values of(Co+Ni+Se+Te)-As and(Co+Ni+Se+Te)/As.The pyrite pyroelectricity of the replacement style is N-type,indicating that it formed under low sulfur fugacity,while that of the quartz vein style is a mixture of P-N types,indicating that it formed under high sulfur fugacity.On the pyroelectricity-temperature diagram,pyrite of the replacement style is mainly distributed between 200 and 270°C,while that of the quartz vein style varies between 90–118 and274–386°C,demonstrating a multistage forming process.In contrast to previous researchers'conclusions,the authors confirm the existence of lattice gold in pyrites through the use of an electron paramagnetic resonance(EPR)test.Au in the form of Au~+,entering pyrite as an isomorph and producing electron–hole centers,makes the centers produce spin resonance absorption and results in EPR absorption peak II.The intensity of auriferous pyrite absorption peak II has certain direct positive correlations with pyrite gold content.The#I and#III absorption peaks of pyrites possibly result from the existence of Ni^(2+)and/or Cu^(2+).γ1,γ2,andγ3 are the strongest and most typical absorption peaks of the infrared spectra of the pyrites.Generally,with the increase in gold content in the pyrite samples,γ1,γ2,andγ3 tend to shift to higher wavenumbers,and the gold content in the pyrite samples has a positive correlation with their relative absorbance.

A low-noise X-band microwave source with digital automatic frequency control for electron paramagnetic resonance spectroscopy

We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer.The microwave source is equipped with a digital automatic frequency control circuit.The parameters of the digital automatic frequency control circuit can be flexibly configured for different experimental conditions,such as the input powers or the quality factors of the resonator.The configurability makes the microwave source universally compatible and greatly extends its application.To demonstrate the ability of adapting to various experimental conditions,the microwave source is tested by varying the input powers and the quality factors of the resonator.A satisfactory phase noise as low as-135 d Bc/Hz at 100-k Hz offset from the center frequency is achieved,due to the use of a phase-locked dielectric resonator oscillator and a direct digital synthesizer.Continuous-wave electron paramagnetic resonance experiments are conducted to examine the performance of the microwave source.The outstanding performance shows a prospect of wide applications of the microwave source in numerous fields of science.

Effects of La, Ce, Y and Tb ions on Free Radical Mediated Peroxidation of Human Erythrocyte Membrane

The effects of the lanthanides in various concentration on the peroxidation of 'ghost' of human erythrocyte with free radicals were studied by methods of fluorometry, spectrophotometry and electron paramagnetic resonance. It is shown that La 3+ and Ce 3+ in the range of 2×10 -4 ～2×10 -7 mol·L -1 inhibit the t BHP mediated peroxidation significantly. Tb 3+ and Y 3+ inhibit the t BHP mediated peroxidation in low concentration (<2×10 -5 mol·L -1 ), but promotes the peroxidation when the concentration is higher than 2×10 -5 mol·L -1 .

Magnetically labeled mesenchymal stem cells after autologous transplantation into acutely injured liver

AIM:To evaluate tracking of magnetically labeled mesenchymal stem cells(MSCs) after intraportal transplantation.METHODS:Mononuclear cells were isolated from bone marrow aspirates of pigs by density gradient centrifugation,cultured and expanded,after which,they were incubated with super paramagnetic iron oxide(SPIO).Prussian blue staining was performed to highlight intracellular iron.To establish swine models of acute liver injury,0.5 g/kg D-galactosamine was administrated to 10 pigs,six of which were injected via their portal veins with SPIO-labeled MSCs,while the remaining four were injected with unlabeled cells.Magnetic resonance imaging(MRI) was performed with a clinical 1.5T MR scanner immediately before transplantation and 6 h,3 d,7 d and 14 d after transplantation.Prussian blue staining was again performed with the tissue slices at the endpoint.RESULTS:Prussian blue staining of SPIO-labeled MSCs had a labeling efficiency of almost 100%.Signal intensity loss in the liver by SPIO labeling on the FFE(T2*WI) sequence persisted until 14 d after transplantation.Histological analysis by Prussian blue staining confirmed homing of labeled MSCs in the liver after 14 d;primarily distributed in hepatic sinusoids and liver parenchyma.CONCLUSION:MSCs were successfully labeled with SPIO in vitro.MRI can monitor magnetically labeled MSCs transplanted into the liver.

RANDOM ATTRACTORS FOR A STOCHASTIC HYDRODYNAMICAL EQUATION IN HEISENBERG PARAMAGNET

This article studies the asymptotic behaviors of the solution for a stochastic hydrodynamical equation in Heisenberg paramagnet in a two-dimensional periodic domain. We obtain the existence of random attractors in H1.

Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance （EPR） spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.

Effect of alcohol exposure on hepatic superoxide generation and hepcidin expression

AIM: To understand the role of mitochondrial-produced superoxide(O 2 ?) in the regulation of iron-regulatory hormone, hepcidin by alcohol in the liver. METHODS: For alcohol experiments, manganese superoxide dismutase knockout mice heterozygous for Sod2 gene expression(Sod2 +/) and age-matched littermate control mice(LMC), expressing Sod2 gene on both alleles, were exposed to either 10%(w/v) ethanol in the drinking water or plain water(control) for 7 d. Total cellular O 2 ? levels in hepatocytes isolated from the livers of mice were measured by electron paramagnetic resonance spectroscopy. The mitochondrial-targeted, O 2 ?-sensitive fluorogenic probe, MitoSOX Red and flow cytometry were utilized to measure O 2 ? in mitochondria. Gene and protein expression were determined by Taqman Real-time quantitative PCR and Western blotting, respectively. RESULTS: Sod2 +/- mice expressed 40% less MnSOD protein(SOD2) in hepatocytes compared to LMC mice. The deletion of Sod2 allele did not alter the basal expression level of hepcidin in the liver. 10% ethanol exposure for 1 wk inhibited hepatic hepcidin mRNA expression three-fold both in Sod2 +/ and LMC mice. O 2 ? levels in hepatocytes of untreated Sod2 +/ mice were three-fold higher than in untreated LMC mice, as observed by electron paramagnetic resonance spectroscopy. O 2 ? levels in mitochondria of Sod2 +/ mice were four-fold higher than in mitochondria of untreated LMC mice, as measured by MitoSOX Red fluorescence and flow cytometry. Alcohol induced a two-fold higher increase in O 2 ? levels in hepatocytes of LMC mice than in Sod2 +/ mice compared to respective untreated counterparts. In contrast, 1 wk alcohol exposure did not alter mitochondrial O 2 ? levels in both Sod2 +/- and control mice. CONCLUSION: Mitochondrial O2 ? is not involved in the inhibition of liver hepcidin transcription and thereby regulation of iron metabolism by alcohol. These findings also suggest that short-term alcohol consumption significantly elevates O 2 ? levels in hepatocytes, which appears not to originate from mitochondria.

Calculations of the Spin-Lattice Coupling Coefficients Fij and Zij for MgO:Co2+Crystal

According to a uniform and simple method of calculating spin-lattice coupling coefficients and the pert1rbation formulas of gi factors and hyperfine structure constants Ai based on the cluster approach for 3d7 ions in cubic,tetragonal and trigonal octahedral crystal fields, the spin-lattice coupling coefficients Fij (F11, Fl2, F44), Zij (Z11, Z12,Z44) and also g factor and hyperfine constant A for MgO:Co2+ are calculated by using the parameters obtained from the optical spectra without adjustable parameters. The calculated results show good agreement with the observed values.The difiiculty in explaining the coeficients Fij and Zij is therefore removed.

Electron paramagnetic resonance characterization of aluminum ion implantation-induced defects in 4H-SiC

Deep-level defects in silicon carbide(SiC)are critical to the control of the performance of SiC electron devices.In this paper,deep-level defects in aluminumion-implanted 4H-SiC after high-temperature annealingwere studied using electron paramagnetic resonance(EPR)spectroscopy at temperatures of 77 K and 123 K under different illumination conditions.Results showed that the main defect in aluminum ion-implanted 4H-SiC was the positively charged carbon vacancy(VC+),and the higher the doping concentration was,the higher was the concentration of VC+.Itwas found that the type of material defectwas independent of the doping concentration,although more VC+defects were detected during photoexcitation and at lower temperatures.These results should be helpful in the fundamental research of p-type 4H-SiC fabrication in accordance with functional device development.

Structural,electrical and magnetic studies on Y-Fe-O system

The compounds of iron substituted yttrium oxide systems have been prepared for the importance in the field of magneto electric materials.The polycrystalline samples of Y2–xFexO3–y(x=0.1,0.2) were prepared by solid-state reaction method.The single-phase formation of these compounds was confirmed by X-ray diffraction studies.It was found that the samples crystallized in tetragonal phase and the lattice parameters were calculated as a=1.0559(7) nm,c=1.0832(9) nm for Y1.9Fe0.1O3–y and a=1.0545(6) nm,c=1.0841(8)...

EPR spectroscopy of whole blood and blood components:can we diagnose abnormalities?

This mini-review gives a brief account of the emergence of the electron paramagnetic resonance(EPR)spectroscopy in the second half of the 20th century and reports the continuous wave EPR spectroscopy studies on human and animal blood.The question posed by this review is whether the EPR spectroscopy in the form it appeared 70 years ago is still able to provide useful information about different pathological conditions in humans,particularly in the area of diagnosis.

Chemical and physical characteristics of quartz from gold deposits in the North China platform: relationship to gold mineralization

This paper seeks to identify macroscopic metallogenic mechanisms of various mineral deposits by studying microscopic typomorphic characteristics of typical minerals associated with the deposits and to reveal the mechanism of lattice gold in detail by studying both physical and chemical characteristics of quartz from representative gold deposits in the North China Platform.As part of their extensive research,the authors examine the relationship between trace elements with wall rock,the ore-forming media,and gold immigration of various types of gold deposits,including their salinity,type,temperature.These are key factors to revealing the mineralization mechanism,and indicators for mineral prospecting,exploration,mining,and metallurgical technology.In order to address the questions posed,the following methods were used:field investigations of geology and sampling of the representative gold deposits,physical study and chemical analysis of quartz including,but not limited to,fluid inclusions as well as their compositions and trace elements in quartz,the unit cell parameters,electron paramagnetic resonance spectrum(EPR),and infrared spectroscopic analysis(ISA).As a result of this study,the authors observe the following key findings:unit cell parameters of quartz vary with their contents of foreign elements including gold,paragenetic stage,wall rock type,and other factors;the higher the forming temperature and the lower the gold content in quartz,the smaller the unit cell parameters,and vice versa.Additionally,the EPR absorption lines resulted from the O–Al defect center.The density of these types of hole centers increases and the EPR signal strengthens when the temperature decreases.Based on the findings,the authors conclude that lattice gold exists in quartz.Gold,in the form of Au^(+)and/or Au^(3+),entering quartz and producing an electron–hole center,namely,the O-Au hole center,makes the center produce spin resonance absorption and results in the EPR absorption peak#I.Both unit cell parameters and EPR of quartz can potentially be used in mineral prospecting,relative ore-forming temperature determination,and grade control during mining.

The composition of acid/oil interface in acid oil emulsions

In well stimulation treatments using hydrochloric acid,undesirable water-in-oil emulsion and acid sludge may produce and then cause operational problems in oil field development.The processes intensify in the presence of Fe(Ⅲ),which are from the corroded surfaces of field equipment and/or iron-bearing minerals of the oil reservoir.In order to understand the reasons of the stability of acid emulsions,acid emulsions were prepared by mixing crude oil emulsion with 15% hydrochloric acid solutions with and without Fe(Ⅲ) and then separated into free and upper(water free) and intermediate(with water) layers.It is assumed that the oil phase of the free and upper layers contains the compounds which do not participate in the formation of acid emulsions,and the oil phase of the intermediate layers contains components involved in the formation of oil/acid interface.The composition of the oil phase of each layer of the emulsions was studied.It is found that the asphaltenes with a high content of sulfur,oxygen and metals as well the flocculated material of protonated non-polar oil components are concentrated at the oil/acid interface.In addition to the above,in the presence of Fe(Ⅲ) the Fe(Ⅲ)-based complexes with polar groups of asphaltenes are formed at the acid/oil interface,contributing to the formation of armor films which enhance the emulsion stability.

Electron paramagnetic resonance studies of the chelate-based ionic liquid in different solvents

The electron paramagnetic resonance spectra of the chelate-based ionic liquid[C_(10)mim][Cu(F_6-acac)_3]in different solvents have been obtained at 120 K.It was found that the values of the^(63)Cu hyperfine coupling constants(A_(IL))of[C_(10)mim][Cu(F_6-acac)_3]in molecular solvents were from 116 to 180 Gauss.Moreover,the A_(IL)values in general ionic liquids are more complicated,and two sets of peaks can often be observed in their electron paramagnetic resonance spectra.Based on the Kamlet-Taft parameters,relative permittivity,the experimental results were discussed in terms of solvation effect and coordination of the solvents.

Evaluation of Chromite Recovery from Shaking Table Tailings by Magnetic Separation Method

This study aimed to evaluate the chromite recovery from shaking table tailings of Forumad plant by a dry high-intensity magnetic separation. The average feed grade of chromium trioxide (Cr2O3) was 7.62% by XRF. Also, different mineral phases were determined by XRD, identifying the presence of Chrysotile, Augite, Albite, Chlorite and Chromite. Although the Forumad plant usually applies gravity methods utilizing the specific gravity difference between chromite and other gangue minerals, this study applied magnetic separation utilizing the paramagnetic nature of chromite crystals to recover chromite from tailings. 27 tests for 3 factors in 3 levels designed by the Taguchi method with design expert 12 software to determine the optimum conditions for the grade and recovery. Finally, the best condition was identified at 10,000 gauss (or 1 tesla) in the magnetic field intensity, 1 kg/min feeding rate, and 40 rpm drum rotating speed which produced a concentrate with 34.65% Cr2O3 and 59.42% recovery.

Paramagnetic Anisotropy of CdGd_2(WO_4)_(4-δ) Single Crystal

CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）^2- , therefore, there were some Gd^2＋ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance （ESR） experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2＋ and Gd^3｜ ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3＋ ions to 63.2% of Gd^2＋ ions in the Gd ions of the CdGd2（WO4）4-δ crystal was calculated, and δ was 0.638 in the single crystal.

X-Ray Diffraction, Electron Paramagnetic Resonance and Optical Absorption Study of Bauxite

The bauxite mineral obtained from Araku, Vishakapatnam district of Andhra Pradesh, India is used in the present work. Structural characterization was performed by X-ray diffraction (XRD). The mineral was found to be gibbsite in phase. The transitional metal ions present were investigated using electron paramagnetic resonance (EPR) and optical absorption spectra. The EPR results suggest that Fe3+ has replaced Al3+ in the unit cell of bauxite. The optical absorption spectrum is due to Fe3+ which indicates that it is in distorted octahedral environment. The near-infrared (NIR) spectrum is due to water fundamentals and combination overtones, which confirm the formula of the compound. The impurities in the mineral are identified using spectroscopic techniques.

The Onset of Ferromagnetic Convection in a Micropolar Ferromagnetic Fluid Layer Heated from Below

The onset of ferromagnetic convection in a micropolar ferromagnetic fluid layer heated from below in the presence of a uniform applied vertical magnetic field has been investigated. The rigid-isothermal boundaries of the fluid layer are considered to be either paramagnetic or ferromagnetic and the eigenvalue problem is solved numerically using the Galerkin method. It is noted that the paramagnetic boundaries with large magnetic susceptibility χ delays the onset of ferromagnetic convection the most when compared to very low magnetic susceptibility as well as ferromagnetic boundaries. Increase in the value of magnetic parameter M1 and spin diffusion (couple stress) parameter N3 is to hasten, while increase in the value of coupling parameter N1 and micropolar heat conduction parameter N5 is to delay the onset of ferromagnetic convection. Further, increase in the value of M1, N1, N5 and χ as well as decrease in N3 is to diminish the size of convection cells.

Model of Preformed Hole-Pairs in c-Axis Transport in Cuprate Superconductors

Model of hole-pairs in electrical transport along ab plane in cuprate superconductors has already been proposed. It has been found to be in the shape of 3dx2–y2 orbital of an electron in an atom. This time, model of hole-pairs in transport along c-axis in cuprate superconductors is proposed. In ab-plane, hole-pairs are formed along CuO2 plane;one hole-pair covering 9 - 10 two dimensional CuO2 unit cells in 3dx2–y2 configuration. In the investigation of c-axis hole-pairs, cuprate superconductors have been sub-divided into three categories depending on the number of CuO2 planes/formula unit. There is a little different treatment for finding out the order parameter in each category. Coherence lengths along ab-planes are of the order of a few tens of Angstroms, whereas along c-axis, they are less than even their a-, b-lattice constants. In cuprates with 2 or 3 CuO2 planes, the order parameter is of 3dz2–x2 type in zx-plane with lobes along both the axes much constrained. For cuprates with a single CuO2 layer, the order parameter is of 3dx2–y2 type, but its dimensions are less than a-, b-lattice constants.