Synthesis and Characterization of Exfoliated Graphite/ABS Composites

Exfoliated graphite was prepared by chemical route and then further subjected to thermal oxidation and sonication for size reduction and increased interlayer spacing in natural flake graphite. Exfoliated graphite/ABS composites were pre-pared with varying filler concentration by solution casting method. Exfoliated graphite and composites were character-ised by scanning electron microscopy and energy dispersive X-ray analysis, Fourier transform infrared spectroscopy and X-ray diffractometry techniques. After thermal exfoliation significant peak of graphite at 2? = 26.4? disappeared completely, confirming successful exfoliation of graphite. SEM images revealed homogeneous dispersion of exfoliated graphite in the matrix and EDAX confirmed successful reduction of graphite oxide.

Quantifying Isotibolone in Raw Materials of Tibolone

Tibolone, a synthetic steroid, is used in the treatment of natural or surgical menopause disturbs resultant of estrogenic deficiency. Isotibolone (Δ4-tibolone) is one of the three active metabolic degradation products of tibolone that displays progestagenic effects on carcinoma cell growth and gene regulation. Isotibolone can be present in raw material of tibolone due to some inadequate synthesis or storage. Its presence is necessary to be identified and quantified in active pharmaceutical ingredients (API), before its use in the manufacturing of medicines. After a recent study on the crystal structure determination of isotibolone, quantitative phase analyses of both tibolone and isotibolone in raw materials and tablets became possible to be conducted. X-ray powder diffraction is one recommended tool for this purpose, but it can be highly frustrating due to the extreme peak overlap when conventional laboratory equipments are used. In this work we show that the use of Brazilian Synchrotron Light Source X-ray powder diffraction data and the Rietveld method can be successfully applied to identify and quantify the isotibolone in two samples of tibolone raw materials.

Chemical Characterization of Auriferous Ores from the Brazilian State of Paraiba

One of the most important problems facing the gold industry is that the placer and free milling gold ores are almost terminating. Hence, the use of refractory ores has been increased during the recent years. In general, gold refractory ores occurs in various types of deposits associated with a range of minerals. Among the refractory ores, the sulfide type is the most common. The methodology employed in the mining process depends on the mode of occurrence of the ore and on the particle size, shape and degree of purity of the auriferous species. We have undertaken a mineralogical investigation of a representative sample of a complex gold mining ore collected in the municipality of Princesa Isabel, Paraiba, Brazil, using X-ray fluorescence spectrometry, X-ray diffractometry, infrared spectroscopy, inductively coupled plasma-atomic emission spectrometry and the Fire Assay. The results showed that the arsenic content of the ore was closely related to the gold content, and that the occurrence of “invisible gold” was associated primarily with pyrite and secondarily with arsenopyrite. The sulfur content of the ore was directly related to its refractoriness. It is concluded that gold mineralization in the study area is mainly of the gold-quartz-sulfide veins (lode gold), while the gold found in the mini-fractures of the deposits is probably associated with the hydrothermal processes that occurred in the region.

Stability of phases in (Ba, Gd)MnO_3 solid solution system

The existing phases in BaxGd1-xMnO3 solid solution system （0≤x≤ 1） were studied by analyzing the detailed crystal structure of each composition from the results of the Rietveld method using powder X-ray diffraction data. For a small substitution of Ba for Gd （0≤x〈0. 1）, the orthorhombic phase with a perovskite type structure （Pnma space group） was stably formed and this fact was supported by the electron diffraction data. There existed an intermediate phase of Ba0.33Gd0.67MnO3, which was characterized as the tetragonal phase with perovskite structure. The composition range of this phase was narrow and almost line compound. Between the regions of these phases, there existed two-phase region. There was also a two-phase region between the intermediate tetragonal phase and BaMnO3. Measurement of electrical conductivities of these orthorhombic solid solutions and tetragonal phases showed semiconducting behaviors for both phases and the existence of the phase transition at high temperature for the orthorhombic phase, The transition temperature decreased as the Ba content increased.

Structural Analysis of a New Phase of BaNdMnO_4

Single crystal of BaNdMnO4 with I4/mmm was synthesized by a floating zone method. A new phase of BaNdMnO4 was obtained by annealing the single crystal in a reducing atmosphere at 573 K for 10 d. The structural change was analyzed by four-circle X-ray diffractometry and transmission electron microscopy. The new phase has an orthorhombic unit cell (Fmmm) of a=0.5486(2) nm, b=0.5484(2) nm, and c=1.3059(2) nm.

REQUIREMENT OF SILICON FLATNESS FOR SILICON DIRECT BONDING TECHNOLOGY

The influence of silicon slice flatness on bonding technology and the relation between a foreign particle and resulting bubble are quantitatively presented by the elastic theory. It is demonstrated experimentally by X-ray double crystal diffractometry and infrared imager.

Isolated attosecond electron wave packet diffraction

Wave-particle duality is one of the most fundamental and mysterious natures of matters. Here, we present an interesting scheme of isolated electron wave packet diffraction with a few-cycle laser pulse and an extreme ultraviolet （XUV） pulse. The diffraction fringes are clearly present in the laser dressed XUV photoelectron spectra, strongly resembling the Airy diffraction pattern of optical waves. This phenomenon suggests a great potential of attosecond diffractometry. According to this scheme we also propose a simple method to determine the XUV pulse duration from the photoelectron spectra with a rather high resolution.

Geochemical Characterization and Mineralogy of Babouri-Figuil Oil Shale,North-Cameroon

Organic geochemistry methods such as high temperature combustion, Rock-Eval pyrolysis and gas analysis were used to analyze oil shale from Babouri-Figuil Basin. Results show that the average content of organic matter is 36.25 %wt, while that of mineral matter is 63.75 %wt. The total organic carbon (TOC) is between 15.93 %wt and 26.82 %wt. The HI vs. Tmax diagram indicates an immature Type I kerogen. The average value of the oil potential (S2b) is 149.95 mg HC/g rock. The gases obtained by retort process are H2, CO2, CO and CnH2n, CnH2n+2. Finally, it emerges that, the organic matter of Babouri-Figuil shales was immature or has just reached the beginning of the oil window. The mineralogical study of Babouri-Figuil oil shale has been carried out by means of XRD (X-Ray Diffractometry) and XRF (X-Ray Fluorescence spectrometry). The results show that mineral matrix contains silica, carbonates, sulphates, oxides and clay minerals. Besides, compounds contain metals and metalloids like Fe, In, Ca. The main oxides are SiO2 (majority), CaO, Fe2O3, Al2O3, SO3, and K2O.

Influence of strontium and lanthanum simultaneous addition on microstructure and mechanical properties of the secondary Al-Si-Cu-Fe alloy

In this paper, modification agents with different contents of Sr and La elements were added into Al-Si-Cu-Fe alloy and the effect on refinement of secondary phases and α-Al grain was investigated by optical microscopy, scanning electronic microscopy and X-ray diffractometry. Tensile testing was carried out to characterize the strength of the alloys. The XRD result indicated that Fe9LaSi4 and SrSi2 phases were formed after Sr and La elements were added in the alloys simultaneously. With the help of metallographic analysis techniques, the length of needle-like phases, mainly composed of eutectic Si and β-Fe, was quantified. And the secondary dendrite arm spacing（SDAS） of α-Al grain was also evaluated. The quantification results indicated that the modification agents with different contents of Sr and La elements showed varied refinement effects on the mean length of needle-like phases and SDAS value. When the addition amount increased, the length of needle-like phase and SDAS value were decreased. The minimum mean length of needle-like phases（Sr/La=1：1） and the SDAS value（Sr/La=1：5） were obtained by setting the addition amount of the modification agent at 0.12 wt.%. The yield strength of the alloy was related to the mean SDAS value, whilst the ultimate tensile strength, elongation and hardness values were related to the mean length of needle-like phase.

AN INVESTIGATION OF PHASES OF GRAIN BOUNDARY IN Si_3N_4 BY EM

Ⅰ. INTRODUCTION Si3N4 ceramics becomes more and more attractive as super high temperature engineering material. However, the strength of this material drops down at above 1000℃. In order to solve this problem, Y2O3 and Al2O3 were used as additives

THE SYNTHESIS, SPECTRAL CHARACTERIZATION AND CRYSTAL STRUCTURE OF Zn(C_6H_(14)N_5O)CI_3

A complex of Zn(C6H14N5O)Cl3 has been synthesized and studied with IR, NMR as well as single crystal X-ray diffractometry.The crystal structure of the complex was determined by single crystal X-ray diffraction analysis and refined by full-matrix least squares to a value of R=0.0385. The

Luminescence of Eu^2＋ and Eu^2＋-Mn^2＋ in sodium scandium diphosphate NaScP2O7 crystal

In this work, the photoluminescence（PL） of NaScP2O7：Eu^2＋ and NaScP2O7：Eu^2＋,Mn^2＋ was investigated. Phase purity was checked using X-ray powder diffractometry（XRD）. PL excitation and emission spectra were recorded to elucidate the PL properties of NaScP2O7：Eu^2＋ and NaScP2O7：Eu^2＋,Mn^2＋. Furthermore, fluorescence lifetime measurements were performed. PL and lifetime measurements were carried out from 10 to 525 K. Moreover, the Eu^2＋ site occupation was discussed. It turned out that the incorporated Eu^2＋ ions substituted for Na＋ site and occupied two different sites. Temperature dependent PL measurements indicated the emission intensity decreased with increasing temperature due to temperature quenching in NaScP2O7：Eu^2＋. Fluorescence lifetimes of Eu^2＋ in NaScP2O7：Eu^2＋ almost did not change with a decay constant τ=~0.53 μs in the temperature range of 10–280 K, and then shortened due to temperature quenching. The luminescent lifetime reached ~0.05 μs at T=525 K. Finally, it was found that energy transfer occurred from Eu^2＋ to Mn^2＋ in co-doped NaScP2O7：Eu^2＋,Mn^2＋.