scholarly journals Acid-basic properties of chromium(III) oxide surface

2021 ◽  
Vol 57 (3) ◽  
pp. 270-277
Author(s):  
E. A. Shaporova ◽  
A. A. Zhukova ◽  
A. K. Baev ◽  
A. Yu. Sidorenko
Keyword(s):  
Binary Systems ◽  
Ionization Constant ◽  
Nitrate Solution ◽  
Structural Features ◽  
Oxide Surface ◽  
Acid Base ◽  
X Ray ◽  
Oxide Hydroxide ◽  
Nanosized Catalysts ◽  
Aqueous Nitrate Solution

The article is devoted to the study of the nature and number of acid-base centers on the surface of chromium(III) oxide obtained by precipitation from an aqueous nitrate solution. The curve of the distribution of the number of acidbase centers of the samples is plotted depending on the indicator of the ionization constant of indicators. It was determined that the main Lewis centers make the main contribution to the acidity of the samples; there are also Bronsted centers of different acidity. A comparative analysis of the structural features of the surface of oxides of chromium, zinc and binary systems Cr (III)–Zn (II) was carried out according to the results of X-ray phase analysis of oxides and thermolysis of the corresponding hydroxides. Based on this, the possibility of obtaining nanosized catalysts based on oxide-hydroxide systems of chromium with a number of 3d-metals obtained in the process of polynuclear hydroxocomplexation is predicted.

scholarly journals A Role of Coagulant in Structure Formation of Fibers and Films Spun from Cellulose Solutions

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3495 ◽  
Author(s):  
Valery Kulichikhin ◽  
Igor Makarov ◽  
Maria Mironova ◽  
Lyudmila Golova ◽  
Markel Vinogradov ◽  
...  
Keyword(s):  
Binary Systems ◽  
Glassy State ◽  
Functional Materials ◽  
Structural Features ◽  
Coagulation Bath ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cellulose Films ◽  
Different Temperatures

Replacing the aqueous coagulation bath with an alcoholic one during spinning cellulose fibers (films) from solutions in N-methylmorpholine-N-oxide leads to a radical restructuring of the hydrogen bonds net of cellulose and, as a result, to a change in the structure and properties of the resulting material. By the method of optical interferometry, it was possible to identify the intrinsic features of the interaction of the solvent and isomeric alcohols and to construct phase diagrams of binary systems describing the crystalline equilibrium. Knowledge of the phase states of the system at different temperatures renders it possible to exclude the process of solvent crystallization and conduct the spinning in pseudo-homogeneous conditions. The structure and morphology of samples were studied using X-ray diffraction and scanning electron microscopy methods for a specific coagulant. When the solution under certain conditions is coagulated at contact with alcohol, the solvent may be in a glassy state, whereas, when at coagulation in water, an amorphous-crystalline structure is formed. The structural features of cellulose films obtained by coagulation of solutions with water and alcohols help to select potential engineering or functional materials (textile, packaging, membranes, etc.), in which their qualities will manifest to the best extent.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

scholarly journals X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

2018 ◽  
Vol 619 ◽  
pp. A138
Author(s):  
V. Perdelwitz ◽  
S. Czesla ◽  
J. Robrade ◽  
T. Pribulla ◽  
J. H. M. M. Schmitt
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Binary Systems ◽  
Uv Light ◽  
Close Binary ◽  
Eclipsing Binary ◽  
X Ray ◽  
Uv Emission ◽  
Low Mass ◽  
Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

scholarly journals Cotton stalk-derived hydrothermal carbon for methylene blue dye removal: investigation of the raw material plant tissues

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Libo Zhang ◽  
Junyan Tan ◽  
Gangying Xing ◽  
Xintong Dou ◽  
Xuqiang Guo
Keyword(s):  
Methylene Blue ◽  
Functional Materials ◽  
Raw Material ◽  
Plant Tissues ◽  
Chemical Compositions ◽  
Waste Biomass ◽  
Cotton Stalk ◽  
Acid Base ◽  
X Ray ◽  
Bet Analysis

AbstractConversion of the abundant agricultural residual cotton stalk (CS) into useful chemicals or functional materials could alleviate the fossil fuels caused energy shortages and environmental crises. Although some advances have been achieved, less attention has been paid to the plant tissues effect. In this study, the plant tissue of CS was changed by part degradation of some components (hemicelluloses and lignin, for example) with the aid of acid/base (or both). The pretreated CS was transformed into hydrochar by hydrothermal carbonization (HTC) method. Morphological and chemical compositions of CS hydrochar were analyzed by various techniques, including elemental analysis, Fourier transform infrared (FTIR), BET analysis, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Methylene blue (MB) removal of prepared CS hydrochar was used to evaluate CS hydrochar pollutions adsorption capacity. Results reveal acid/base (or both) pretreatment is beneficial for CS raw material to prepare high-quality CS hydrochar. The effects of some parameters, such as initial MB concentration, temperature, pH value and recyclability on the adsorption of MB onto both acid and base-pretreated CS hydrochar (CS-H2SO4 + NaOH-HTC) were studied. The present work exhibits the importance of agricultural waste biomass material plant tissues on its derived materials, which will have a positive effect on the direct utilization of waste biomass.

scholarly journals A Machine Learning Approach For Classifying Low-mass X-ray Binaries Based On Their Compact Object Nature

2020 ◽  
Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  
Keyword(s):  
Machine Learning ◽  
Black Hole ◽  
Neutron Star ◽  
Binary Systems ◽  
Compact Object ◽  
X Ray ◽  
Average Accuracy ◽  
Machine Learning Approach ◽  
Low Mass ◽  
X Ray Binaries

Abstract Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25 keV obtained from the Rossi X-ray Timing Explorer archive. We report an average accuracy of 87±13% in classifying the spectra of LMXB sources. We further use the trained model for predicting the classes for LMXB systems with unknown or ambiguous classification. With the ever-increasing volume of astronomical data in the X-ray domain from present and upcoming missions (e.g., SWIFT, XMM-Newton, XARM, ATHENA, NICER), such methods can be extremely useful for faster and robust classification of X-ray sources and can also be deployed as part of the data reduction pipeline.

scholarly journals X-Ray Sources in Close Binary Systems

1974 ◽  
Vol 3 ◽  
pp. 89-107
Author(s):  
M. J. Rees
Keyword(s):  
Binary Systems ◽  
Close Binary ◽  
Rapid Variability ◽  
X Ray ◽  
Close Binary Systems ◽  
General Order ◽  
Typical Distances ◽  
Astronomical Research ◽  
Orbital Periods ◽  
Galactic Sources

The discovery by Giacconi and his colleagues of variable X-ray sources in close binary systems certainly ranks as one of the highlights of astronomical research during the last 3 years. These remarkable objects have already been extensively studied, by optical and radio observations as well as in the X-ray band; and they seem likely to prove as significant and far-reaching in their implications as pulsars.The ‘Third Uhuru Catalogue’ (Giacconi et al., 1973a) contains about 160 sources, of which about 100 lie in our Galaxy. Their distribution over the sky (together with other arguments) suggests that these sources have luminosities of the general order 1036–1038 erg s−1, and that their typical distances are ˜ 10kpc. These galactic sources generally display rapid variability. Little else is known about most of them, but they are probably of the same general class as systems such as Her X1, Cen X3, Cyg X1 and Cyg X3. These sources have been investigated in detail, and in all cases one infers a system where the X-ray source is orbiting around a relatively ordinary star. Six sources have been optically identified, and there are some others whose binary nature is established by the occurrence of an X-ray eclipse. Orbital periods range from 4.8 h (Cyg X3) up to ˜ 10 days.

Mechanical and Structural Properties of Superhard TiAlSiN Coatings Deposited by Arc Ion Plating of Cylindrical Cathode

2014 ◽  
Vol 783-786 ◽  
pp. 1426-1431
Author(s):  
Wang Ryeol Kim ◽  
Min Chul Kwon ◽  
Jung Hoon Lee ◽  
Uoo Chang Jung ◽  
Won Sub Chung
Keyword(s):  
Structural Properties ◽  
Nitrogen Pressure ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ion Plating ◽  
Arc Current ◽  
Cathode Arc ◽  
Cathodic Arc ◽  
Tialsin Coating

TiAlSiN coatings were deposited on WC-Co metal by using a cathodic arc ion deposition method of cylindrical cathode. We used Ti / Al (50 / 50 at.%) arc target and silicon sputter target. The influence of the nitrogen pressure, TiAl cathode arc current, bias voltage, and deposition temperature on the mechanical and the structural properties of the films were investigated. The structural features of the films were investigation in detail using X-ray diffraction. And coatings were characterized by means of FE-SEM, nanoindentation, Scratch tester, Tribology tester, XRD and XPS. The hardness of the film reached 43 GPa at the cathode arc current of 230 A and decreased with a further increase of the arc current. And the adhesion of the film reached 34 N. The results showed that the TiAlSiN coating exhibited an excellent mechanical properties which application for tools and molds.

Aqueous acid–base chemistry involving dioxovanadium(V) complexes of 2,6-pyridinedimethanol, and the X-ray structures of Na[VO2{2,6-(OCH2)2NC5H3}]·4H2O and [1-H-2,6-(HOCH2)2NC5H3]+Cl−

2006 ◽  
Vol 359 (1) ◽  
pp. 248-256 ◽  
Author(s):  
Raena J. Fites ◽  
Adam T. Yeager ◽  
T.L. Sarvela ◽  
William A. Howard ◽  
Guang Zhu ◽  
...  
Keyword(s):  
Acid Base ◽  
X Ray ◽  
Aqueous Acid

Correlation Between the V-I Characteristics of (0001) 4H-SiC PN Junctions Having Different Structural Features and Synchrotron X-ray Topography

2008 ◽  
Vol 1069 ◽  
Author(s):  
Ryoji Kosugi ◽  
Toyokazu Sakata ◽  
Yuuki Sakuma ◽  
Tsutomu Yatsuo ◽  
Hirofumi Matsuhata ◽  
...  
Keyword(s):  
High Energy ◽  
Structural Features ◽  
Incidence Geometry ◽  
Voltage Source ◽  
Large Area ◽  
Chip Area ◽  
Power Mosfets ◽  
X Ray ◽  
Pn Junctions ◽  
The Difference

ABSTRACTIn practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

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