Narrow Results

An analysis to the characteristics of Co, Mg and Cu ferrites that were prepared using sol–gel method and annealed at $800^{\circ }$C for 1 hour, performed using X-ray diffraction and Raman spectroscopy for structural characteristics, while the Vibrating Sample Magnetometer (VSM), was used for the magnetic characteristics. The X-ray analysis of both cobalt and magnesium ferrites shows a reverse crystal structure of a cubic spinel, while copper ferrite shows a tetragonal crystal structure characteristic at this annealing temperature. The lattice constant (a) was found to be $a=8.186$ for CoFe₂O₄, $a=8.199$ for MgFe₂O₄ and $a=5.969$ for CuFe₂O₄. The Raman spectrum confirms a spinel crystalline form of the prepared ferrites where a likely distribution of cation is indicated at the tetrahedral and octahedral sites. The peaks of the Raman shift appear between 200–800cm${}^{-1}$. These peaks indicate the formation of ferrites. The hysteresis loop of CoFe₂O₄ indicates a hard magnet material. Cu ferrites have relatively lower remnants and magnetocrystalline anisotropy, which indicates soft magnetic characteristics even though it showed higher coercivity. The squareness ratio (Mr/Ms) values varied between 0.52, 0.13 and 0.57 for CoFe₂O₄, MgFe₂O₄ and CuFe₂O₄, respectively. These insights highlight the possibility of tuning the properties of ferrites using a cost-effective sol–gel method.

We review contributions made towards the elucidation of CO and O₂ binding geometries in respiratory proteins. Nuclear magnetic resonance, infrared spectroscopy, Mössbauer spectroscopy, X-ray crystallography and quantum chemistry have all been used to investigate the Fe–ligand interactions. Early experimental results showed linear correlations between ¹⁷O chemical shifts and the infrared stretching frequency (ν_CO) of the CO ligand in carbonmonoxyheme proteins and between the ¹⁷O chemical shift and the ¹³CO shift. These correlations led to early theoretical investigations of the vibrational frequency of carbon monoxide and of the ¹³C and ¹⁷O NMR chemical shifts in the presence of uniform and non-uniform electric fields. Early success in modeling these spectroscopic observables then led to the use of computational methods, in conjunction with experiment, to evaluate ligand-binding geometries in heme proteins. Density functional theory results are described which predict ⁵⁷Fe chemical shifts and Mössbauer electric field gradient tensors, ¹⁷O NMR isotropic chemical shifts, chemical shift tensors and nuclear quadrupole coupling constants (e²qQ/h) as well as ¹³C isotropic chemical shifts and chemical shift tensors in organometallic clusters, heme model metalloporphyrins and in metalloproteins. A principal result is that CO in most heme proteins has an essentially linear and untilted geometry (τ = 4 °, β = 7 °) which is in extremely good agreement with a recently published X-ray synchrotron structure. CO/O₂ discrimination is thus attributable to polar interactions with the distal histidine residue, rather than major Fe–C–O geometric distortions.

Para-aminosubstituted nitrosoarenes react with Ru(CO)(OEP) or [Co(TPP)(THF)₂]SbF₆ (OEP^2- = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion, TPP^2- = 5,10,15,20-tetraphenylporphyrinato dianion) to generate Ru(OEP)(ONC₆H₄NMe₂)₂ and [Co(TPP)(ONC₆H₄NR₂)₂]SbF₆ (R = Me, Et), respectively, in fair to high yields. These N-bound nitrosoarene complexes have been characterized by spectroscopic methods. The complexes Ru(OEP)(ONC₆H₄NMe₂)₂ and [Co(TPP)(ONC₆H₄NMe₂)₂]ClO₄ have also been characterized by single-crystal X-ray crystallography. Their structures represent the first reported solid-state structures of Ru and Co porphyrins containing C-nitroso ligands.

The alignment effect on the L-shell ionization of Nb atom (Z=41) by 0.84MeV, 1.38MeV and 2.92MeV proton impact was investigated. The polarization of L_ℓ X-rays emitted from the aligned niobium target was measured with the crystal spectrometer combined with a position sensitive proportional counter. The experimental values of the degree of alignment A₂ were compared with the prediction of PWBA theory. It results that the experimental value of A₂ in 1.38MeV proton impact was much larger than the theoretical one, and A₂ of 0.84MeV almost coincides with that of 2.92MeV.

The quantitative changes of elements in blood plasma were observed with the passage of time after X-ray whole body irradiation with 12 Gy on C57BL/6J mice by PIXE method. From 4 days after irradiation, dead mouse was found and all mice died by 8 days. Hematocrit (Ht) values indicated a decrease from the 1st day, but on days 3 and 4 there was a small rise. Finally the values became 64 % of that of non-irradiated control on day 7, it was just before death. By analysis with PIXE method, 15 elements were observable in blood plasma of control mice. The elements such as P, S, Cl, K, Ca and Cr were abundant and Fe and Br followed. As trace elements, the peaks of Zn, Cu and Ni were clearly observed. After irradiation, K and Ca decreased on day 1st, afterwards increased gradually. On the contrary, the elements, S, Cl, were rather stable. While Fe decreased from 1st day, Cu increased from the day 2. Zn and Ni showed intensely down and rise in amount, and decreased on day 7. The results of possible measurement of the changes in amount of these elements of blood plasma suggest PIXE method is an easy and useful way for diagnosis.

The quantitative changes in the elements, amounts of Cl, K, Ca, in blood plasma were measured by PIXE method. The samples were obtained at appropriate intervals after transplantation of EL-4 tumor cells in three strains of mice, C57BL/6J (H-2^b), C57BL/10J (abbreviation: B10; H-2^b) and A/J (H-2^a). Transplanted EL-4 tumor cells proliferated in both strains of C57BL/6J and B10. In A/J mice, transplanted EL-4 cells proliferated about 10 days and then were rejected completely by the immunological reaction according to the difference of major histocompatibility antigens. The amounts of Cl in plasma remained at similar level in the time course in any strains, but K fluctuated in C57BL/6J and B10, and less in A/J. On the other hand, Ca showed always higher values in C57BL/6J than other two strains of mice. In B10 mice, Ca increased just before death, but in A/J it decreased at the time of healing by rejection. These changes of Ca in the three strains of mice were related quantitatively 10 the hematocrit values of these strains of mice after transplantation of EL-4 cells.

The inclusion of metamorphic buffer layers (MBL) in the design of lattice-mismatched semiconductor heterostructures is important in enhancing reliability and performance of optical and electronic devices. These metamorphic buffer layers usually employ linear grading of composition, and materials including In_xGa_1-xAs and GaAs_1-yP_y have been used. Non-uniform and continuously graded profiles are beneficial for the design of partially-relaxed buffer layers because they reduce the threading dislocation density by allowing the distribution of the misfit dislocations throughout the metamorphic buffer layer, rather than concentrating them at the interface where substrate defects and tangling can pin dislocations or otherwise reduce their mobility as in the case of uniform compositional growth. In this work we considered heterostructures involving a linearly-graded (type A) or step-graded (type B) buffer layer grown on a GaAs (001) substrate. For each structure type we present minimum energy calculations and compare the cases of cation (Group III) and anion (Group V) grading. In addition, we studied the (i) average and surface in-plane strain and (ii) average misfit dislocation density for heterostructures with various thickness and compositional profile. Moreover, we show that differences in the elastic stiffness constants give rise to significantly different behavior in these two commonly-used buffer layer systems.

We study the behavior of the numbers in 412 light curves of cataclysmic variables, x-ray binary systems, galaxies, pulsars, supernovae remnants and other x-ray sources present in the public data collected by the instrument All Sky Monitor on board of the satellite Rossi x-ray timing explorer. The temporal light curves were analyzed applying Newcomb-Benford Law. The first digit of the x-ray light curves coming from astrophysical systems obeys the Newcomb-Benford Law as an intrinsic behavior. The nonextensive statistical mechanics behavior of astrophysical sources seem to be the cause for these sources to obey the Newcomb-Benford law. Some x-ray binary systems, however, do not follow this behavior. These systems obey either a gaussian or a bimodal distribution.

The effect of partial substitution of Ca by Eu, Sm and Er on the structural, transport and magnetic properties of (Bi_1.6Pb_0.4)Sr₂(Ca_1-xRE_x)₂Cu₃O_y superconductors ceramics (0≤x≤0.025) have been investigated. The substitution of Eu, Sm and Er at the Ca site induced the decrease of the volume fraction for the 2223 phase and the increase of 2212 and 2201 phase volume fractions. The rate of depression for the critical temperature in x=0.015 samples found to be nearly the same for all of these substitutions. The nature of T_c suppression may be attributed to the increase of oxygen content in Bi₂O₂ double layers with increasing Eu, Sm and Er concentrations. The samples shows a linear dependence of intergranular temperature as a function of AC field amplitude, which is in agreement with Muller critical state model.

Ru_1-xSb_xSr₂(Eu_0.7Ce_0.3)₂Cu₂O_10-δ systems were prepared by conventional solid state reaction method. The structural analysis was investigated using X-ray diffraction. Electrical resistivity, Hall effect and magnetic susceptibility measurements on Ru:1222 doped with Sb are presented, together with results in the temperature range 5–300 K. Transition temperature decreases from 43 K for x = 0.00 to 20 K for x = 0.06 Sb. This may be due to a distortion of RuO₆ octahedral, which is responsible of the increase in hole localization. The Hall effect anomalous decreases below T_magnetic which may be explained within a simple two-band model by a transition from localized to more itinerant behavior in the RuO₂ layer at T_magnetic. The behavior of magnetic susceptibility is caused by an antisymmetric exchange coupling of the Dzyaloshinsky–Morya type between neighboring Ru moments.

The structural development of nylon6/layered silicate nanocomposite during zone-drawing was studied using X-ray scattering and dynamic mechanical thermal analysis. The γ form, which was favored in the pressed film, was converted into the α form during zone-drawing. The newly developed α form, during zone-drawing, has a better orientation than the existing γ form, thus supporting the claim that the α form crystallizes away from the polymer-silicate inter-phase region during drawing. The degree of orientation of the layered silicate, projected along the TD direction, increases with the increase of the draw ratio, suggesting that the layered silicate has become straighter during zone-drawing, although the layered silicate within the zone-drawn film buckled perpendicular to the draw direction. The β transition of the dynamic mechanical thermal analysis is independent of the crystalline phase, although the α transition is strongly dependent upon the crystalline phase. This can be explained by the free volume that exists in the inter-phase between the γ lamellar and the layered silicate.

We have systematically studied the X-ray radiation effects on PZT thin ceramic disk provided by CTS Communications Components, Inc using the X-ray beam line in the Center for Advanced Micro-Structure and Devices (CAMD) in Baton Rouge, Louisiana. The photo energies of the X-ray range from 2000 eV to 8000 eV. The beam size is 10.0cm×1.0cm.We measure the dielectric constant in situ with different dose of the radiation in one sample and in different samples. The dielectric constants as a function of radiation dose are presented in the paper. It demonstrates the effects on the dielectric constant. Unexpectedly, we also found that X-ray radiation on the PZT disk generates charges on the surface of the samples. We measured the surface voltage due to the X-ray radiation with different radiation dose at the same temperature for these samples. This founding may have application potential for photoelectric devices. This is just a preliminary study. More thorough investigations are needed.

Polycrystalline solid solution of phosphate and vanadate lead calcium apatites Pb_{10 -x}Ca_x(VO₄)₁(PO₄)₅(OH)₂ apatites [x = 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0] was reduced with hydrogen gas at the temperature of 300 and 400°C for 1 h. All these compounds were investigated by XRD and ESR spectroscopy. Only one reduced oxidation state V⁺⁴ was detected. Two types of species like isolated vanadium (+4) and clusters of V⁴⁺ had been observed. The stability of the apatites increases and the particle size of the crystal decreases with calcium doping concentrations. As the concentrations of Ca increase the intensity of ESR lines deviates due to the spin–lattice relaxation interactions. The deviation in the intensity of ESR spectra can be attributed as the coexistence of paramagnetic and antiferromagnetic phases in the apatites.

A survey of recent studies of biaxial liquid crystals (LCs), whose nematic and/or smectic-A phases do not possess optical uniaxiality (viz., more than one optical axis exists), is given in this review. In particular, we emphasize on how Nuclear Magnetic Resonance (NMR) spectroscopy can help to advance the understanding of phase biaxiality in general, and to examine recent debates on the existence of biaxial nematic phase reported in low molecular mass bent-core or V-shaped mesogens. A general discussion of orientational order parameters is detailed, particularly in smectic-C (SmC) and biaxial nematic phases. How these orientational order parameters can be determined by various techniques such as NMR, IR absorbance and Raman scattering studies, will be mentioned. Recent X-ray observations of SmC clusters in the nematic phase of V-shaped mesogens are highlighted and contrasted with probable theory. Moreover, deuterium and carbon-13 NMR techniques are briefly reviewed, and their possible utilization to identify phase biaxiality in these biaxial LC systems is explored.

The systems MgCuZnFe₂O₄ doped (0–0.6 wt% Ta) are prepared by the general ceramic method using the sintering temperature at 1200°C. The variations of the sintered density, lattice parameter, jump length of electrons, and initial permeability were studied. A maximum density was obtained at 1200°C during the preparation process. The electrical resistivity decreases with increasing tantalum (Ta) content upto 0.1 wt% and then increases for higher concentrations. The initial permeability and the change carries mobility increase upto 0.1 Ta and then decreases. The jump length decreases with enhancing Ta ions because the substitution of Ta ion with small size instead of Fe³⁺ at the A sites increase the concentration of iron ions at the B sites. The increase of the iron content causes the decrease of the jump length of electrons between Fe³⁺ and Fe²⁺. These improvements of the magnetic properties give some light about the importance of these compositions to be used in technology.

Solution cast technique has been used to prepare films of PVA and its blend with PVP. Moreover, cobalt chloride (CoCl₂) has been doped in PVA and also PVA/PVP 90/10 as a host matrix for it. Also, UV/VIS optical analysis has been used to drop more light on the structural modification that occurs due to doping CoCl₂ with different levels in different polymeric matrixes. Indeed, UV–Vis spectra is a useful tool for studying the absorption spectra and estimating the values of absorption edge, E_g, and band tail, E_u, for all samples. The optical absorption measurements have been carried out in the wavelength region from 200 nm to 900 nm. In addition, the ligand field parameters and optical energy gaps have been calculated and discussed. X-ray diffraction (XRD) and fourier transform infrared (FTIR) spectroscopy have been used to characterize the studied samples which illustrates that PVA is strongly affected by mixed fillers.

A solid solution of phosphate and vanadate lead apatites Pb₁₀(PO₄)_6-x(VO₄)x(OH)₂ (x = 0.5, 1.0, 2.0, 3.0, and 6.0) were reduced with hydrogen gas at temperature 300°C for one hour. All these compounds were investigated by XRD and ESR spectroscopy. Only one reduced oxidation state, V⁴⁺, was detected. Two types of species-like isolated vanadium (+ 4) and clusters of V⁴⁺ were observed. The EPR powder spectrum computer simulations were performed using the program Simfonia from Bruker. Spin Hamiltonian parameters were also calculated. As the concentrations of vanadium ions increase to 2.0, the intensity of the ESR lines increases, and x = 3.0 the intensity of the ESR line decreases sharply. After this concentration, i.e. x > 3.0, there is again an increase in the intensity. The variation of the line shape and intensity of the ESR spectra can be attributed to increases in the hopping rate of the charge carriers (polarons) in different apatite compositions.

The angular distribution of W-$L_{\alpha }$, $L_{\beta 1}$ and $L_{\beta 2}$ X-rays induced by 13.1 keV bremsstrahlung has been measured at different emission angles from 110${}^{\circ }$ to 140${}^{\circ }$ at intervals of 10${}^{\circ }$. The investigation of angular dependence of $L$ X-ray intensity ratios by bremsstrahlung is barely found in previous works. The $L_{\beta 1}$ X-ray yield shows isotropic emission, while the measured $L_{\alpha }$ and $L_{\beta 2}$ X-ray yields are found to be spatially anisotropic. At last, the anisotropy parameters for $L_{\alpha }$ and $L_{\beta 2}$ X-rays have been derived.

In this paper, a nonlinear least squares estimator based on the extending cost function is derived, and its performance is analyzed in a Monte-Carlo simulation. Numerical results show that estimation error of the pulse time of arrival satisfies the normal distribution, the relation between the variance and the number of X-ray photon obtained by our simulation is compared with the analytical model. In addition, the effect of time bin size on the statically behavior of estimation error is also studied. This work holds great promise for designing the parameters of X-ray camera adopted in the pulsar navigation system.

This paper presents the research results on the microstructure changes of SKD61 steel after quenching at 1050${}^{\circ }$C and then tempering at 580${}^{\circ }$C. After quenching and tempering, the microstructure of this steel is determined by various moieties, including tempering martensite, residual austenite, and carbides dispersed within the matrix. Scanning electron microscopy, X-ray, and energy-dispersive spectroscopic analysis reveal that the presence of the carbides Cr₇C₃, Mo₃C₂ and MoC determines the mechanical properties of steel during high-temperature operations.