scholarly journals Image-based dissolution analysis for tracking the surface stability of amorphous powders

ADMET & DMPK ◽  
2020 ◽  
Author(s):  
Jernej Štukelj ◽  
Mikael Agopov ◽  
Jouko Yliruusi ◽  
Clare J. Strachan ◽  
Sami Svanbäck
Keyword(s):  
Amorphous Materials ◽  
Particle Surface ◽  
Storage Conditions ◽  
High Energy ◽  
Particle Analysis ◽  
Recrystallization Process ◽  
Surface Stability ◽  
C 23 ◽  
Amorphous Drugs ◽  
Amorphous Powders

<p class="ADMETabstracttext">Poor solubility of crystalline drugs can be overcome by amorphization – the production of high-energy disordered solid with improved solubility. However, the improved solubility comes at a cost of reduced stability; amorphous drugs are prone to recrystallization. Because of recrystallization, the initial solubility enhancement is eventually lost. Therefore, it is important to understand the recrystallization process during storage of amorphous materials and its impact on dissolution/solubility. Here, we demonstrate the use of image-based single-particle analysis (SPA) to consistently monitor the solubility of an amorphous indomethacin sample over time. The results are compared to the XRPD signal of the same sample. For the sample stored at 22 °C/23 % relative humidity (RH), full crystallinity as indicated by XRPD was reached around day 40, whereas a solubility corresponding to that of the γ crystalline form was measured with SPA at day 25. For the sample stored at 22 °C/75 % RH, the XRPD signal indicated a rapid initial phase of crystallization. However, the sample failed to fully crystallize in 80 days. With SPA, solubility slightly above that of the crystalline γ form was measured already on the second day. To conclude, the solubility measured with SPA directly reflects the solid-state changes occurring on the particle surface. Therefore, it can provide vital information – in a straightforward manner while requiring only minuscule sample amounts – for understanding the effect of storage conditions on the dissolution/solubility of amorphous materials, especially important in pharmaceutical science.</p>

Combustion of Boron Nano-Particles in Ethanol Spray Flame

2010 ◽  
Author(s):  
Srinibas Karmakar ◽  
Sumanta Acharya ◽  
Kerry M. Dooley
Keyword(s):  
Energy Density ◽  
Particle Surface ◽  
Combustion Process ◽  
High Energy ◽  
Nano Particles ◽  
High Energy Density ◽  
Particle Analysis ◽  
Fuel Additive ◽  
Hydrocarbon Combustion ◽  
Spray Flame

Biofuels such as ethanol have lower energy density than conventional petroleum-based fuels, and therefore enhancing its energy density via addition of high-energy density components is an attractive option. Boron is an attractive fuel additive because it has among the highest volumetric heating value among potentially suitable additives. The present study deals with an experimental investigation of boron combustion in an ethanol spray flame. A constant low particle loading density of boron nanoparticles (60nm SMD), around 1% (by weight) of the liquid fuel flow rate, has been used. Though it has high energetic potential, the combustion process of boron is retarded by the initial presence of the oxide coating the particle surface. In the present study, measurements have been made of the emission of intermediate sub-oxide like BO2 using spectroscopy and imaging with interference filters. The effect of boron on the hydrocarbon combustion has also been studied by examining the heat release and product mole fractions. In addition, particle characterization has been carried out to know the size, surface structure/composition of the injected boron nano powders using XRD, XPS and TEM. A preliminary investigation has also been performed on the burnt particle collected from the exhaust structure using XRD. The chemiluminescence and spectroscopic signatures indicate that boron combustion is facilitated and that hydrocarbon combustion is enhanced. The particle analysis shows differences in the imaged and spectroscopic characteristics of the unburnt and burnt nano-particles reflecting the particle-combustion processes.

Al-La-Ni-Fe Amorphous Alloys and Amorphous-Crystalline Composites Produced by Mechanical Alloying

2006 ◽  
Vol 510-511 ◽  
pp. 290-293 ◽  
Author(s):  
Pyuck Pa Choi ◽  
Ji Soon Kim ◽  
O.T.H. Nguyen ◽  
Dae Hwan Kwon ◽  
Young Soon Kwon
Keyword(s):  
Spherical Shape ◽  
High Energy ◽  
Size Mismatch ◽  
Atomic Size ◽  
Stage Crystallization ◽  
Dsc Analyses ◽  
Amorphous Powders ◽  
Compositional Changes ◽  
La Addition ◽  
Constituent Elements

Al-La-Ni-Fe alloys of three different compositions (Al82La10Ni4Fe4, Al85La9Ni3Fe3 and Al88La6Ni3Fe3) were prepared high-energy milling in a planetary ball-mill (AGO-2). Complete amorphization was observed for the Al82La10Ni4Fe4 alloy after milling for 350 h at a rotational speed of 300 rpm. In contrast, the Al85La9Ni3Fe3 and Al88La6Ni3Fe3 powders contained the FCC Al phase even for prolonged milling. The amorphization tendency was found to increase in the order of Al88La6Ni3Fe3 < Al85La9Ni3Fe3 < Al82La10Ni4Fe4, which may well be ascribed to the increasing atomic size mismatch of the constituent elements on La addition. DSC analyses of amorphous samples revealed two-stage crystallization processes for all three alloys, however, with strong variations in the thermal stability upon compositional changes. As observed by SEM, amorphous powders consisted of particles with nearly spherical shape and diameters ranging from 5 to 20 µm.

Immobilization of Elastomers at the Carbon Black Particle Surface

1970 ◽  
Vol 43 (5) ◽  
pp. 973-980 ◽  
Author(s):  
A. K. Sircar ◽  
A. Voet
Keyword(s):  
Carbon Black ◽  
Particle Surface ◽  
Carbon Black Particle ◽  
High Energy ◽  
Molecular Weights ◽  
Boiling Points ◽  
Furnace Black ◽  
Bound Rubber ◽  
Black Surface ◽  
Black Particle

Abstract Determinations have been made of the amount of elastomer unextractable from unvulcanized masticated mixes with carbon black by a given solvent at boil, expressed as immobilized elastomer. Saturated and unsaturated elastomers varying in molecular weights from 2000 to 325,000, were used, while solvents of greatly differing boiling points and solvent power were employed. It could be shown that the bonding between elastomers and carbon black is not a simple adsorption, but involves a higher energy interaction, defined as chemisorption. At successively higher temperatures elastomer is increasingly removed from the carbon black surface. The temperature Tm, obtained by extrapolation of the linear relationship between amounts immobilized and temperature of extraction, represents the temperature theoretically required to eliminate all bonds between carbon black and elastomer and is therefore indicative of the bond strength. Data suggest the existence of a bonding energy spectrum. Upon graphitization, blacks show a considerable decline in high energy bonding ability for elastomers. Saturated elastomers show less bonding than unsaturated elastomers with the same furnace black. “Bound rubber” represents the sum total of physically adsorbed, mechanically entangled, and chemisorbed elastomer. The actual values are greatly dependent upon the procedure used. “Immobilized rubber”, indicating chemisorbed elastomer, is easily determined, is not influenced by the method, and is more significant as an indicator of reinforcement.

The Influence of High-Energy Ball Milling and Sintering Process on the Microstructure and Mechanical Properties of Al-Ni-Y-Co-La Alloy

2013 ◽  
Vol 745-746 ◽  
pp. 281-285
Author(s):  
Y.B. Yuan ◽  
Rui Xiao Zheng ◽  
Su Jing Ge ◽  
Han Yang ◽  
Chao Li Ma
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Ball Milling ◽  
Amorphous Materials ◽  
Volume Fraction ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Process Conditions ◽  
Bulk Alloy ◽  
Energy Ball

Al86Ni7Y4.5Co1La1.5 (at.%) alloy powder was produced by argon gas atomization process. After high-energy ball milling, the powder was consolidated and extruded by using vacuum hot press sintering under different process conditions, sintering temperature, extrusion pressure, sintering time, etc.. The microstructure and morphology of the powder and consolidated bulk alloy were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase transformation of the powder was investigated by differential scanning calorimetry (DSC). Mechanical properties of the consolidated bulk alloy were examined. The results showed that as the milling time increase, the volume fraction of amorphous materials and the hardness and yield strength of the bulk alloy were obvious improved.

scholarly journals Michel Borghini as a Mentor and Father of the Theory of Polarization in Polarized Targets

2016 ◽  
Vol 40 ◽  
pp. 1660116
Author(s):  
Wim de Boer
Keyword(s):  
Amorphous Materials ◽  
High Energy Physics ◽  
High Energy ◽  
Spin Interaction ◽  
Dynamic Polarization ◽  
Spin Interactions ◽  
High Dynamic ◽  
Polarized Targets ◽  
First Time ◽  
Energy Physics

This paper is a contribution to the memorial session for Michel Borghini at the Spin 2014 conference in Bejing, honoring his pivotal role for the development of polarized targets in high energy physics. Borghini proposed for the first time the correct mechanism for dynamic polarization in polarized targets using organic materials doped with free radicals. In these amorphous materials the spin levels are broadened by spin-spin interactions and g-factor anisotropy, which allows a high dynamic polarization of nuclei by cooling of the spin-spin interaction reservoir. In this contribution I summarize the experimental evidence for this mechanism. These pertinent experiments were done at CERN in the years 1971 - 1974, when I was a graduate student under the guidance of Michel Borghini. I finish by shortly describing how Borghini’s spin temperature theory is now applied in cancer therapy.

Strain measurement in metallic glasses and metallic-glass-matrix composites by means of x-ray scattering

2005 ◽  
Vol 903 ◽  
Author(s):  
Todd Hufnagel ◽  
Ryan T. Ott ◽  
Jon Almer
Keyword(s):  
Metallic Glass ◽  
Elastic Strain ◽  
Glass Matrix ◽  
Amorphous Materials ◽  
Single Scattering ◽  
High Energy ◽  
Matrix Composites ◽  
Crystalline Phases ◽  
Metallic Glass Matrix Composite ◽  
Glass Matrix Composites

AbstractThe availability of high-energy synchrotron beamlines has made it possible to study the development of elastic strain in crystalline phases in metallic-glass-matrix compositesin situduring loading, and to measure elastic strain in amorphous materials as well. In this paper, we discuss experimental techniques and data analysis for these measurements and give examples. We show that the strain in both the amorphous and crystalline phases in a metallic-glass-matrix composite can be extracted from a single scattering pattern.

Studies of local and intermediate range structure in crystalline and amorphous materials at high pressure using high-energy X-rays

2007 ◽  
Vol 22 (2) ◽  
pp. 108-112 ◽  
Author(s):  
Lars Ehm ◽  
Sytle M. Antao ◽  
Jiuhua Chen ◽  
Darren R. Locke ◽  
F. Marc Michel ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Atomic Structure ◽  
Amorphous Materials ◽  
High Energy ◽  
Liquid Gallium ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Current State

The method of high-energy total elastic X-ray scattering to determine the atomic structure of nanocrystalline, highly disordered, and amorphous materials is presented. The current state of the technique, its potential, and limitations are discussed with two successful studies on the pressure induced phase transition in mackinawite (FeS) and the high-pressure behavior of liquid gallium.

scholarly journals PDF Analysis on a Laboratory System: Adapting the Experiment to the Material

2014 ◽  
Vol 70 (a1) ◽  
pp. C870-C870
Author(s):  
Céleste Reiss ◽  
Milen Gateshki ◽  
Marco Sommariva
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Amorphous Materials ◽  
Nearest Neighbors ◽  
High Energy ◽  
Experimental Point ◽  
Laboratory System ◽  
Crystalline Materials ◽  
X Ray ◽  
Pdf Analysis

The increased interest in recent years regarding the properties and applications of nanomaterials has also created the need to characterize the structures of these materials. However, due to the lack of long-range atomic ordering, the structures of nanostructured and amorphous materials are not accessible by conventional diffraction methods used to study crystalline materials. One of the most promising techniques to study nanostructures using X-ray diffraction is by using the total scattering (Bragg peaks and diffuse scattering) from the samples and the pair distribution function (PDF) analysis. The pair distribution function provides the probability of finding atoms separated by a certain distance. This function is not direction-dependent; it only looks at the absolute value of the distance between the nearest neighbors, the next nearest neighbors and so on. The method can therefore also be used to analyze non-crystalline materials. From experimental point of view a typical PDF analysis requires the use of intense high-energy X-ray radiation (E ≥ 20 KeV) and a wide 2θ range. After the initial feasibility studies regarding the use of standard laboratory diffraction equipment for PDF analysis [1-3] this application has been further developed to achieve improved data quality and to extend the range of materials, environmental conditions and geometrical configurations that can be used for PDF experiments. Studies performed on different nanocrystalline and amorphous materials of scientific and technological interest, including organic substances, oxides, metallic alloys, etc. have demonstrated that PDF analysis with a laboratory diffractometer can be a valuable tool for structural characterization of nanomaterials. This contribution presents several examples of laboratory PDF studies, in which the experimental conditions have been successfully adapted to match the specific requirements of materials under investigation.

Magnetic and Mössbauer study of multiphase Fe-Zr amorphous powders obtained by high energy ball milling

2000 ◽  
Vol 12 (13) ◽  
pp. 3101-3112 ◽  
Author(s):  
R Pizarro ◽  
J S Garitaonandia ◽  
F Plazaola ◽  
J M Barandiarán ◽  
J M Grenèche
Keyword(s):  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Mössbauer Study ◽  
Energy Ball ◽  
Amorphous Powders

Mechanical Alloying for Preparation of Ti50Fe45Sn5 Amorphous Alloys Powder

2011 ◽  
Vol 480-481 ◽  
pp. 104-108
Author(s):  
Ge Wang ◽  
Chun Zhang ◽  
Yu Ying Zhu ◽  
Zhi Gang Chao ◽  
Qiang Li
Keyword(s):  
Mechanical Alloying ◽  
Amorphous Alloys ◽  
Weight Ratio ◽  
Supercooled Liquid ◽  
High Energy ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Typical Morphology ◽  
Amorphous Powders

Ti50Fe45Sn5 amorphous alloys powder was prepared by mechanical alloying (MA) in a high-energy planetary ball mill. The non-crystallization degree was tested by X-ray diffraction (XRD). It was shown from the XRD results that a higher ball to powder weight ratio (BPR) is advantageous in preparing amorphous alloys powder. The microstructure and shape of the powder was observed by scanning electron microscope (SEM). It was shown from the SEM results that the as-milled amorphous alloys powder is flake shape and assembles together to be agglomeration structure, which is a typical morphology of amorphous powders prepared by MA. Thermodynamic properties and crystallization kinetics behavior of the as-milled amorphous alloys powder were measured by differential scanning calorimeter (DSC). The supercooled liquid region △Tx is broad (up to 119K) and the reduction glass transforming temperature Trg (0.78) is great, which shows that the as-milled amorphous alloys powder has a strong glass-forming ability and the thermal stability of the powder is excellent.

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