Investigation of prior image constrained compressed sensing-based spectral X-ray CT image reconstruction

To improve spectral X-ray CT reconstructed image quality, the energy-weighted reconstructed image xbins^W and the separable paraboloidal surrogates（SPS） algorithm are proposed for the prior image constrained compressed sensing（PICCS）-based spectral X-ray CT image reconstruction. The PICCS-based image reconstruction takes advantage of the compressed sensing theory, a prior image and an optimization algorithm to improve the image quality of CT reconstructions.To evaluate the performance of the proposed method, three optimization algorithms and three prior images are employed and compared in terms of reconstruction accuracy and noise characteristics of the reconstructed images in each energy bin.The experimental simulation results show that the image xbins^W is the best as the prior image in general with respect to the three optimization algorithms; and the SPS algorithm offers the best performance for the simulated phantom with respect to the three prior images. Compared with filtered back-projection（FBP）, the PICCS via the SPS algorithm and xbins^W as the prior image can offer the noise reduction in the reconstructed images up to 80. 46%, 82. 51%, 88. 08% in each energy bin,respectively. M eanwhile, the root-mean-squared error in each energy bin is decreased by 15. 02%, 18. 15%, 34. 11% and the correlation coefficient is increased by 9. 98%, 11. 38%,15. 94%, respectively.

Elemental and proximate analysis of coal by x-ray fluorescence assisted laser-induced breakdown spectroscopy

Although laser-induced breakdown spectroscopy(LIBS),as a fast on-line analysis technology,has great potential and competitiveness in the analysis of chemical composition and proximate analysis results of coal in thermal power plants,the measurement repeatability of LIBS needs to be further improved due to the difficulty in controlling the stability of the generated plasmas at present.In this paper,we propose a novel x-ray fluorescence(XRF) assisted LIBS method for high repeatability analysis of coal quality,which not only inherits the ability of LIBS to directly analyze organic elements such as C and H in coal,but also uses XRF to make up for the lack of stability of LIBS in determining other inorganic ash-forming elements.With the combination of elemental lines in LIBS and XRF spectra,the principal component analysis and the partial least squares are used to establish the prediction model and perform multi-elemental and proximate analysis of coal.Quantitative analysis results show that the relative standard deviation(RSD) of C is 0.15%,the RSDs of other elements are less than 4%,and the standard deviations of calorific value,ash content,sulfur content and volatile matter are 0.11 MJ kg,0.17%,0.79% and 0.41%respectively,indicating that the method has good repeatability in determination of coal quality.This work is helpful to accelerate the development of LIBS in the field of rapid measurement of coal entering the power plant and on-line monitoring of coal entering the furnace.

Synthesis, Spectral Characterization and Thermal Behavior of Newly Derived La(III), Co(III) and Mn(II) Complexes with Schiff Base Derived from Methionine and Salicylaldehyde

Many metal complexes of Schiff base derived from different amino acids are widely employed as biologically active materials, especially as antibacterial agents. Three new metal [Co(III), Mn(II) and La(III)] complexes with the Schiff base (L) derived from salicylaldehyde and amino acid (methionine) were synthesized and investigated by using various physico-chemical techniques such as elemental analysis, FTIR, UV-visible spectroscopy, magnetic measurement, thermo gravimetric analysis (TGA) and X-ray powder diffraction (XRD) method. From spectral studies, it has been concluded that the synthesized ligand acts as a tetra-dentate molecule, coordinates metal through azomethine nitrogen, sulfur, phenolic oxygen and carboxylate oxygen. UV-visible spectrophotometry showed the characteristic absorption bands corresponding to a square planar geometry for La(III) and Mn(II) metal complexes and tetrahedral geometry for Co(III) complex. The XRD data demonstrated that the manganese and cobalt complexes were crystalline but the lanthanum complex was amorphous in nature. The empirical formula of the synthesized complexes based on analytical data were [Co(C12H13SNO3)]·(NO3), [La(C12H13SNO3)](Cl)(H2O) and [Mn (C12H13SNO3)].

Simulating Medical Imaging X-Ray Tubes with Various Parameters Using BEAMnrc Monte Carlo Software

Context: Medical imaging has a wide range of applications in today’s society. Basic projectional radiography, CT scans, mammograms and a range of other advanced technologies all use x-rays to create a large number of examinations every day across the world. The most essential component of such medical equipment is the x-ray tube, which creates and produces x-rays. Objective: We describe and investigate an abstract model-geometry of a simple x-ray tube utilizing the open-source software package of BEAMnrc of the EGSnrcmp family, which is well validated by several studies over the years, for high and low energy photons generation. Methodology: Our research focuses on two different electron beam energies: 120 keV and 30 keV. The 120 keV is the typical energy for simple projectional radiographic exams and CT examinations, whereas the 30 keV is the typical energy of mammography. Results: Two different anode materials are used for each case, Gold (Au) and Tungsten (W) for 120 keV because these are the most common in projectional radiography and CT;Molybdenum (Mo) and Rhodium (Rh) for 30 keV because with these targets most mammography exams are carried out. The aim of this work is to show how the BEAMnrc software package can simulate effectively x-ray generation of low-energy photons which are utilized in modern medical imaging procedures. We describe useful information on anode-target characteristics, such as anode angle, anode material, and metal filter materials, based on previous quality studies even by using software other than BEAMnrc. Conclusion: We demonstrate that BEAMnrc can be efficiently used for Monte Carlo modeling of low-energy photons.

基于透射测量X射线谱的重建方法

对透射测量X射线谱两种重建方法进行评估。医用直线加速器产生的最大能量为10MeV X射线谱，用蒙特卡罗方法（Montecarlo，MC）模拟得到的值作为基准X射线谱，代入矩阵系统AF=T得到的穿透系数T，由穿透系数T分别应用谱向量代数法（Spectra vectorial algebra，SVA）与双共轭梯度法（Biconjugate gradients，BiCG）来解矩阵系统AF=T，得到重建后的该X射线谱-↑F0与基准X射线谱F相比较，BiCG法比SVA法重建后的X射线谱声更加接近F，且T引入白高斯噪声项，以模拟穿透系数的测量误差，这一结果依然成立。当信噪比SNR高于90dB时，BiCG法比SVA法重建的X射线谱结果更理想。

Isolation and Crystal Structure of Trans-2,2',4,4'-tetramethyl-6,6'-dinitro Azobenzene

Trans-2,2?,4,4?-tetramethyl-6,6?-dinitro azobenzene (C16H16N4O4, Mr = 328.32) was isolated from benzene extract of the leaves of Aconitum sungpanense Hand. Mazz. as a new compound, and characterized by spectral methods and X-ray diffraction analysis. It crystallizes in monoclinic system, space group P21/c with a = 8.544(1), b = 13.997(2), c = 7.161(1) ? ?= 112.97(1), V = 788.4(2) ?, Z = 4, Dc = 1.383 g/cm3, F(000) = 344 and ?MoKa) = 0.102 mm-1. The final R = 0.0395 and wR = 0.1140 for 1913 independent reflections with Rint = 0.0109 and 1329 observed reflections with I > 2s(I). The molecule is composed of two phenyl rings through trans N=N.

Synthesis and Crystal Structure of 3-(4-Ethoxyphenyl)-6-(phenoxymethyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole

The title compound C18H16N4O2S has been synthesized by the reaction of 4-amino-3-（4-ethoxyphenyl）-5-mercapto-1,2,4-triazole with phenoxyacetic acid in phospho- rus oxychloride, and characterized by IR, NMR spectra and elemental analysis. Its structure was determined by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 1.4903（3）, b = 1.5230（2）, c = 0.9615（16） nm, Z = 4, V = 1.7769（5） nm^3, Dc = 1.317 g/cm^3, μ = 0.201 mm^-1, F（000） = 736, R = 0.0795 and wR = 0.2233. In the title compound, all rings are essentially planar.

Features of the Mineral Composition of the Quaternary Sediments of the Development Areas of the Erosion Processes on the Territory of the Tunkinsk’s Depression

The article considers the some features of the Quaternary sediments mineral composition of the development areas of the erosion processes on the territory of the Tunkinsk’s depression.Main objectives of our research are to determine the entering forms of Na,Mg,Al,Si,P,S,K,Ca,Ti,Cr,Mn,Fe,Zn,Cu,Zr,and Ba in the composition of the investigated sediments.The mineral composition was studied by the method of an electron probe X-ray spectral microanalysis(XRM)using wave spectrometers,and the method of X-ray diffraction analysis.The localization centers of Cr,Cu,Zn,Zr,and Ba were established in the mineral composition of the studied sediments.Maximum content of BaO(14.42 wt%)was detected in alkali K-feldspar in the clay sediments of modern alluvial complex(aQ4).Crystallochemical formulas of different minerals were obtained.

Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier power.Quasi-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is derived.Strong anti-correlation between BT and luminosity of Cyg X-1 is found.After removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 X-1.The results support that they harbor intermediate mass black holes(IMBHs).

EXTRA-SOFT X-RAY EXCESS OF QUASARS

In a quasar sample with strong soft X-ray emission, we construct a sample of extra-soft X-ray excess quasars in virtue of the relation between the hydrogen column density, NH (IPC), determined by Einstein IPC, and NH (21cm), determined by Galactic 21cm line. The X-ray spectral index a*E in the energy interval 0.3keV<E<0.5keV is calculated. a*E is obviously larger than the spectral index αE in 0.5keV<E<3.5keV, showing that 0.3-0.5keV is just the rapidly decreasing part of the right side of big bump from UV to soft X-ray.These results will help establish the composite model for this kind of big bump.

Plasma Heating Device Based on Electron Beam Irradiation

Currently, large-scale equipment is essential for heating plasma. In this study, based on the theoretical investigation of high-current electron beam applications, a new method for heating plasma is proposed. If this method is successful, fusion power can be generated much more easily and inexpensively than using conventional methods. This study considered the theoretical possibility of generating ultrahigh-temperature plasma by confining plasma particles between the anode (positive potential) and electric fields using Rutherford scattering of particles forming a heavy-mass-positive-ion layer. In order to form this deuteron-positive ion layer, hydrogen gas is encapsulated in a closed container and applied to a negative with an insulator film on the inner surface. Next, the gas is ionized by irradiating a high-current electron.

Characterization of optical transitions of Eu^(3+) in lanthanum oxychloride nanophosphor

This paper presented the studies on the optical properties and calculation of spectral parameters of europium doped lanthanum oxychloride nanophosphor for their possible applications in optoelectronic devices. The compound was doped with 0.1 mol% Eu3＋ ions. The X-ray diffraction study of prepared sample suggested the tetragonal structure with particle size in the range of 18–21 nm. The photoluminescence （PL） emission spectra showed the bright emission in orange-red region from 580 to 630 nm. The most intense emission peak at 621 nm was due to transition 5D0→7F2 in energy levels of Eu3＋ ions. The spectral parameters were calculated from the absorption and emission spectra using Judd-Ofelt intensity parameters. The calculated values of the oscillator strength corresponding to the three transitions 7F1→5D1, 7F1→5D2 and 7F0→5D2 observed at 535, 472 and 465 nm in absorption spectra were 0.30×10–6, 1.36×10–6 and 0.63×10–6, respectively. The value of transi- tion probability （A）, stimulated emission cross-section （ ） and radiative lifetime （τrad） corresponding to 621 nm emission peak （transition 5D0→7F2） were 308 s–1, 1.22×10–21 cm2 and 3.24×10–3 s, respectively.

Optical design and optimization study of metrology sector at high energy photon source

Introduction X-ray metrology,including the metrological calibration of X-ray detectors,optical elements and sources,is important for many frontier science,such as X-ray astronomy,EUV-lithography,plasma physics.Among many types of X-ray sources,synchrotron-radiation is considered perfect for X-ray metrology,mainly due to that arbitrarily X-rays specifications can be tailored to meet the demands of metrological calibration of X-ray detectors and optical elements.As a consequence,many metrology beamlines around the world are built,upgrading or to be constructed,including the metrology sector to be constructed at High Energy Photon Source(HEPS).Method One reasonable way to access good metrological data is using a stable X-ray beam,which means that beam position as well as flux should be as constant as possible and the beamline configuration should be simple and robust to reduce the uncertainty from beamline itself.In addition,the spectral purity of monochromatic X-rays is another crucial factor for X-ray metrology,which means stray X-rays and harmonic X-rays must be as low as possible.Many measures are taken to satisfy these requirements.Conclusion An optical design of the metrology sector optimized for synchrotron-radiation-based-metrology is described here.The metrology sector,ranging from 50 eV to 20 keV,will be set up to meet the growing needs of X-ray metrology in China.All beamlines’configurations are simple and easy to use,with an acceptable ratio of high-order harmonics and stray X-rays,which can be under 1%in the entire energy range.