scholarly journals The Behavior of Americium in Aqueous Carbonate Systems

1983 ◽  
Vol 26 ◽  
Author(s):  
R. J. Silva
Keyword(s):  
Experimental Data ◽  
Solubility Product ◽  
Computer Code ◽  
Formation Constants ◽  
Solid Materials ◽  
X Ray ◽  
Solid Phases ◽  
Diffraction Patterns ◽  
Carbonate Complexes

ABSTRACTThe solubilities of crystalline Am(OH)3 and AmOHCO3 were measured at 25° C in aqueous solutions of 0.1 M NaCl04 by determination of the solution concentrations of Am. Prior to use in the measurements, the solid materials were characterized by their x-ray powder diffraction patterns. The solubility product quotients were calculated from the experimental data. The hydrolysis quotients of Am3+ were also estimated from the hydroxide solubility data. Using the thermodynamic data derived from these experiments and the recently reported formation constants for the Am3+ carbonate complexes, the solid phases and concentrations of solution species of americium in several aqueous carbonate systems were calculated using the computer code MINEQL.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

Determining the energy-dependent X-ray flux variation of a synchrotron beamline using Laue diffraction patterns

2011 ◽  
Vol 44 (1) ◽  
pp. 177-183 ◽  
Author(s):  
Catherine Dejoie ◽  
Martin Kunz ◽  
Nobumichi Tamura ◽  
Colin Bousige ◽  
Kai Chen ◽  
...  
Keyword(s):  
Incident Energy ◽  
Flux Variation ◽  
Laue Diffraction ◽  
X Ray ◽  
Measured Flux ◽  
Highly Sensitive ◽  
Diffraction Patterns ◽  
Energy Dependent ◽  
Flux Curve

Although the spectrum originating from a superconducting bending magnet is quasi-continuous, it shows important intensity variations through its spectral range. A method to determine the incident energy-dependent flux variation based on the comparison between observed intensities and the calculated intensities of a well known structure (calcite) is presented here. It is found that the measured flux is highly sensitive to the use of correct Debye–Waller factors for the atoms of the standard crystal. By using the measured flux curve, it was possible to unambiguously index the Laue diffraction pattern of a trigonal crystal structure in its hexagonal setting. This is a crucial but difficult first step for the determination of strain and stress in materials with this symmetry, such as quartz, Mg, Ti, Znetc.

scholarly journals Using Bayesian Model Selection to Advise Neutron Reflectometry Analysis from Langmuir-Blodgett Monolayers

2019 ◽  
Author(s):  
Andrew McCluskey ◽  
Tom Arnold ◽  
Joshaniel F. K. Cooper ◽  
Tim Snow
Keyword(s):  
Experimental Data ◽  
Soft Matter ◽  
General Framework ◽  
Neutron Reflectometry ◽  
Analytical Models ◽  
Colloid Interface ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Generic Framework

The analysis of neutron and X-ray reflectometry data is important for the study of interfacial soft matter structures. However, there is still substantial discussion regarding the analytical models<br>that should be used to rationalise relflectometry data. In this work, we outline a robust and generic framework for the determination of the evidence for a particular model given experimental data, by<br>applying Bayesian logic. We apply this framework to the study of Langmuir-Blodgett monolayers by considering three possible analytical models from a recently published investigation [Campbell et al., J. Colloid Interface Sci, 2018, 531, 98]. From this, we can determine which model has the most evidence given the experimental data, and show the effect that different isotopic contrasts of neutron reflectometry will have on this. We believe that this general framework could become an important component of neutron and X-ray reflectometry data analysis, and hope others more regularly consider the relative evidence for their analytical models.<br>

EVALUATION OF THE STRESSED DEFORMED STATE OF MAIN GAS PIPELINES RUNNING IN PERMANENTLY FROZEN GROUNDS

2020 ◽  
pp. 58-63
Author(s):  
M. M. Sidorov ◽  
N. I. Golikov ◽  
R. P. Tihonov
Keyword(s):  
Experimental Data ◽  
Calculated Data ◽  
Gas Pipeline ◽  
Loss Of Stability ◽  
Portable Equipment ◽  
Ray Method ◽  
X Ray ◽  
Deformed State ◽  
Pipeline Monitoring

The work evaluates the stress deformed state of the section of the interfield gas collecting main, running in permanently frozen grounds. The object of research is a section of a pipeline with an arched discharge formed as a result of loss of stability as a result of thermal erosion of permanently frozen grounds to disturbance of the vegetation cover. The determination of stresses was carried out by the X-ray method using portable equipment. The experimental data were analyzed with the calculated. The calculated data were obtained by measuring the spatial position of the gas pipeline section. The obtained values of the acting stresses and the estimates of the critical indicators of the gas pipeline monitoring section made it possible to reasonably estimate the stress state. The methodology for determining the acting stresses of pipelines using portable X-ray equipment can be successfully applied to estimate the stressed-deformed state of pipeline systems running in the zone of permafrost.

Solubility and Complex-Ion Equilibria

2021 ◽  
pp. 313-324
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Metal Complexes ◽  
Solubility Product ◽  
Formation Constants ◽  
Aqueous Systems ◽  
Complex Ions ◽  
Ionic Compounds ◽  
Molar Solubility ◽  
Solubility Product Constant ◽  
Complex Ion

Solubility and Complex-Ion Equilibria broadens the previous chapter’s coverage of equilibria to include aqueous systems containing two or more solutes of slightly soluble ionic compounds and the formation of metal complexes in solution. Solubility equilibria which allow quantitative predictions of how much of a compound will dissolve under given conditions are covered. The meaning of the solubility product constant (K sp) and how to calculate it from molar solubility values is presented. Also discussed is determination of molar solubility from K sp. Calculations demonstrate how to predict the formation of a precipitate by comparing the ion product or solubility quotient (Q) with K sp. Formation constants of complex ions and calculations involving complex ion equilibria are explained.

scholarly journals Synthesis of the Modifications of Ca2SiO4 and the Determination of their Powder X-ray Diffraction Patterns

1963 ◽  
Vol 71 (806) ◽  
pp. 63-68 ◽  
Author(s):  
Goro YAMAGUCHI ◽  
Yoshio ONO ◽  
Shigeo KAWAMURA ◽  
Yoshiaki SODA
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Variance and centroid optimization in X-ray powder diffraction analysis

1993 ◽  
Vol 8 (2) ◽  
pp. 89-97 ◽  
Author(s):  
G. Berti
Keyword(s):  
Experimental Data ◽  
Constrained Optimization ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Instrumental Effects ◽  
Line Profiles ◽  
X Ray ◽  
Visualization In Scientific Computing ◽  
Diffraction Effects

Line profiles of a powder diffraction pattern and the aberrations which affect the centroid and the variances of the peaks have been analyzed using the visualization in scientific computing (ViSC) systems. The constrained optimization of those aberrations has been derived from the theory developed by Wilson (1963). It allows the determination of systematic instrumental effects and gives indication of other diffraction effects related to the samples. The CuKβradiation was used to process the experimental data directly as it is comprised of only one single wavelength.

scholarly journals Determination of nanostructure of liposomes containing two model drugs by X-ray scattering from a synchrotron source

2013 ◽  
Vol 20 (5) ◽  
pp. 721-728 ◽  
Author(s):  
Alexandr Nasedkin ◽  
Jan Davidsson ◽  
Mont Kumpugdee-Vollrath
Keyword(s):  
Experimental Data ◽  
Small Angle ◽  
Structural Parameters ◽  
Water Layer ◽  
Synchrotron Source ◽  
X Ray ◽  
X Ray Scattering ◽  
Extract Information ◽  
Ray Scattering

Small-angle X-ray scattering has been employed to study how the introduction of paracetamol and acetylsalicylic acid into a liposome bilayer system affects the system's nanostructure. An X-ray scattering model, developed for multilamellar liposome systems [Pabstet al.(2000),Phys. Rev. E,62, 4000–4009], has been used to fit the experimental data and to extract information on how structural parameters, such as the number and thickness of the bilayers of the liposomes, thickness of the water layer in between the bilayers, size and volume of the head and tail groups, are affected by the drugs and their concentration. Even though the experimental data reveal a complicated picture of the drug–bilayer interaction, they clearly show a correlation between nanostructure, drug and concentration in some aspects. The localization of the drugs in the bilayers is discussed.

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