A site-saturated mutagenesis study of pentaerythritol tetranitrate reductase reveals that residues 181 and 184 influence ligand binding, stereochemistry and reactivity.

PubMed

Toogood, Helen S; Fryszkowska, Anna; Hulley, Martyn; Sakuma, Michiyo; Mansell, David; Stephens, Gill M; Gardiner, John M; Scrutton, Nigel S

2011-03-21

We have conducted a site-specific saturation mutagenesis study of H181 and H184 of flavoprotein pentaerythritol tetranitrate reductase (PETN reductase) to probe the role of these residues in substrate binding and catalysis with a variety of α,β-unsaturated alkenes. Single mutations at these residues were sufficient to dramatically increase the enantiopurity of products formed by reduction of 2-phenyl-1-nitropropene. In addition, many mutants exhibited a switch in reactivity to predominantly catalyse nitro reduction, as opposed to CC reduction. These mutants showed an enhancement in a minor side reaction and formed 2-phenylpropanal oxime from 2-phenyl-1-nitropropene. The multiple binding conformations of hydroxy substituted nitro-olefins in PETN reductase were examined by using both structural and catalytic techniques. These compounds were found to bind in both active and inhibitory complexes; this highlights the plasticity of the active site and the ability of the H181/H184 couple to coordinate with multiple functional groups. These properties demonstrate the potential to use PETN reductase as a scaffold in the development of industrially useful biocatalysts. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of impurities on optical properties of pentaerythritol tetranitrate

NASA Astrophysics Data System (ADS)

Tsyshevskiy, Roman; Sharia, Onise; Kuklja, Maija M.

2012-03-01

Despite numerous efforts, the electronic nature of initiation of high explosives to detonation in general and mechanisms of their sensitivity to laser initiation in particular are far from being completely understood. Recent experiments show that Nd:YAG laser irradiation (at 1064nm) causes resonance explosive decomposition of PETN samples. In an attempt to shed some light on electronic excitations and to develop a rigorous interpretation to these experiments, the electronic structure and optical properties of PETN and a series of common impurities were studied. Band gaps (S0→S1) and optical singlet-triplet (S0→T1) transitions in both an ideal material and PETN containing various defects were simulated by means of state-of-the-art quantum-chemical computational techniques. It was shown that the presence of impurities in the PETN crystal causes significant narrowing of the band gap. The structure and role of molecular excitons in PETN are discussed.

Synthesis and Characterization of Energetic Plasticizer AMDNNM

NASA Astrophysics Data System (ADS)

Schulze, Maxwell C.; Chavez, David E.

2016-04-01

The synthesis of room temperature liquid azidomethyl-dinitroxydimethyl-nitromethane (AMDNNM, 5) in 57% overall yield and its formulation with nitrocellulose (AMDNNM/NC) are described. The small-scale explosive sensitivity of neat AMDNNM was determined to be slightly more sensitive than PETN, whereas AMDNNM/NC is significantly less sensitive. Both neat AMDNNM and AMDNNM/NC have thermal stabilities similar to that of pentaerythritol tetranitrate (PETN). The explosive and chemical properties of this novel material make it a good candidate for an energetic plasticizer.

Indirect Determination of Pentaerythritol Tetranitrate (PETN) with a gold nanoparticles-based colorimetric sensor.

PubMed

Üzer, Ayşem; Yalçın, Uğur; Can, Ziya; Erçağ, Erol; Apak, Reşat

2017-12-01

Pentaerythritol tetranitrate (PETN) is the nitrate ester of pentaerythritol, used as an energetic and filling material for military and civilian purposes and rarely for terrorist actions. As there is no reliable nano-colorimetric method for PETN assay, we developed an indirect method based on the determination of nitrite, obtained by reduction of nitrate derived from the alkaline hydrolysis of PETN with H 2 O 2 . We colorimetrically determined the final product, nitrite, by both conventional Griess reaction and a recently developed gold nanoparticle-4-aminothiophenol-N-(1-naphthyl)-ethylenediamine (AuNP-4-ATP+NED) method. Nitramines (RDX and HMX), if present, could be degraded by alkaline hydrolysis, without affecting PETN. The analytical performance characteristics of the developed assays as molar absorptivity (ε), limits of detection (LOD) and quantification (LOQ) were: ɛ=1.06×10 5 L mol -1 cm -1 , LOD=0.03mgL -1 and LOQ=0.11mgL -1 for indirect Griess method; ɛ=1.9×10 4 Lmol -1 cm -1 ; LOD=0.12mgL -1 and LOQ=0.4mgL -1 for AuNP-4-ATP+NED method. Both methods were applied to a 1:1 (w/w) mixture of PETN and TNT (corresponding to the composition of military explosive 'Pentolite'). In order to eliminate the interference from TNT, the Meisenheimer anion of TNT formed in alkaline medium was retained on a strongly basic anion exchange resin column. As PETN had a very low solubility in water, common soil ions could be eliminated by prewashing the sample with water, or in acetone-water mixtures, Ca 2+ , K + , Cl - , SO 4 2- , and NO 3 - could be tolerated at equal (1:1) mass ratios. Soil nitrates and nitrites, at a mass ratio of 50:1, could be separated from PETN with the aid of their insolubilities in acetone and of their retention affinity toward a strongly basic anion-exchange resin. The developed method was statistically validated against a reference GC-MS method. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular dynamics simulations of flame propagation along a monopropellant PETN coupled with multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Jain, S.; Mo, G.; Qiao, L.

2017-02-01

Reactive molecular dynamics simulations were conducted to study the flame speed enhancement phenomenon of a solid mono-propellant, Pentaerythritol Tetranitrate (PETN), when coupled to highly conductive multi-walled carbon nanotubes (MWCNTs). The simulations were based on the first-principles derived reactive force field, ReaxFF, which includes both the physical changes such as thermal transport and the chemical changes such as bond breaking and forming. An annular deposition of a PETN layer around the MWCNTs was considered. The thickness of the PETN layer and the diameter of the MWCNT were varied to understand the effect of the MWCNT loading ratio on the flame propagation. Flame speed enhancements up to 3 times the bulk value were observed. An optimal MWCNT loading ratio was determined. The enhancement was attributed to the layering of the PETN molecules around the MWCNT, which increased the heat transport among the PETN molecules near the MWCNT surface, thus causing the flame to travel faster. Furthermore, a stronger ignition source was required for the MWCNT-PETN complex because of the higher thermal transport among the PETN molecules along the MWCNT, which makes the ignition energy dissipate more quickly. Lastly, the MWCNT remained unburned during the PETN combustion process.

49 CFR 173.57 - Acceptance criteria for new explosives.

Code of Federal Regulations, 2010 CFR

2010-10-01

... must be subjected to the Drop Weight Impact Sensitivity Test (Test Method 3(a)(i)), the Friction... substance has a friction sensitiveness equal to or greater than that of dry pentaerythrite tetranitrate (PETN) when tested in the Friction Sensitivity Test; (4) The substance fails to pass the test criteria...

Structure-Based Insight into the Asymmetric Bioreduction of the C=C Double Bond of α,β-Unsaturated Nitroalkenes by Pentaerythritol Tetranitrate Reductase

PubMed Central

Toogood, Helen S.; Fryszkowska, Anna; Hare, Victoria; Fisher, Karl; Roujeinikova, Anna; Leys, David; Gardiner, John M.; Stephens, Gill M.; Scrutton, Nigel S.

2009-01-01

Biocatalytic reduction of α- or β-alkyl-β-arylnitroalkenes provides a convenient and efficient method to prepare chiral substituted nitroalkanes. Pentaerythritol tetranitrate reductase (PETN reductase) from Enterobacter cloacae st. PB2 catalyses the reduction of nitroolefins such as 1-nitrocyclohexene (1) with steady state and rapid reaction kinetics comparable to other old yellow enzyme homologues. Furthermore, it reduces 2-aryl-1-nitropropenes (4a-d) to their equivalent (S)-nitropropanes 9a-d. The enzyme shows a preference for the (Z)-isomer of substrates 4a-d, providing almost pure enantiomeric products 9a-d (ees up to > 99%) in quantitative yield, whereas the respective (E)-isomers are reduced with lower enantioselectivity (63-89% ee) and lower product yields. 1-Aryl-2-nitropropenes (5a, b) are also reduced efficiently, but the products (R)-10 have lower optical purities. The structure of the enzyme complex with 1-nitrocyclohexene (1) was determined by X-ray crystallography, revealing two substrate-binding modes, with only one compatible with hydride transfer. Models of nitropropenes 4 and 5 in the active site of PETN reductase predicted that the enantioselectivity of the reaction was dependent on the orientation of binding of the (E)- and (Z)-substrates. This work provides a structural basis for understanding the mechanism of asymmetric bioreduction of nitroalkenes by PETN reductase. PMID:20396603

A Fast Liquid Chromatography Tandem Mass Spectrometric Analysis of PETN (Pentaerythritol Tetranitrate), RDX (3,5-Trinitro-1,3,5-triazacyclohexane) and HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) in Soil, Utilizing a Simple Ultrasonic-Assisted Extraction with Minimum Solvent.

PubMed

Anilanmert, Beril; Aydin, Muhammet; Apak, Resat; Avci, Gülfidan Yenel; Cengiz, Salih

2016-01-01

Direct analyses of explosives in soil using liquid chromatography tandem mass spectrometry (LC-MS/MS) methods are very limited in the literature and require complex procedures or relatively high amount of solvent. A simple and rapid method was developed for the determination of pentaerythritol tetranitrate (PETN), 3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), which are among the explosives used in terrorist attacks. A one-step extraction method for 1.00 g soil with 2.00 mL acetonitrile, and a 8-min LC-MS/MS method was developed. The detection limits for PETN, RDX and HMX were 5.2, 8.5 and 3.4 ng/g and quantitation limits were 10.0, 24.5, 6.0 ng/g. The intermediate precisions and Horwitz Ratio's were between 4.10 - 13.26% and 0.24 - 0.98, in order. This method was applied to a model post-blast debris collected from an artificial explosion and real samples collected after a terrorist attack in Istanbul. The method is easy and fast and requires less solvent use than other methods.

Persistence of pentolite (PETN and TNT) in soil microcosms and microbial enrichment cultures.

PubMed

Arbeli, Ziv; Garcia-Bonilla, Erika; Pardo, Cindy; Hidalgo, Kelly; Velásquez, Trigal; Peña, Luis; C, Eliana Ramos; Avila-Arias, Helena; Molano-Gonzalez, Nicolás; Brandão, Pedro F B; Roldan, Fabio

2016-05-01

Pentolite is a mixture (1:1) of 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN), and little is known about its fate in the environment. This study was aimed to determine the dissipation of pentolite in soils under laboratory conditions. Microcosm experiments conducted with two soils demonstrated that dissipation rate of PETN was significantly slower than that of TNT. Interestingly, the dissipation of PETN was enhanced by the presence of TNT, while PETN did not enhanced the dissipation of TNT. Pentolite dissipation rate was significantly faster under biostimulation treatment (addition of carbon source) in soil from the artificial wetland, while no such stimulation was observed in soil from detonation field. In addition, the dissipation rate of TNT and PETN in soil from artificial wetland under biostimulation was significantly faster than the equivalent abiotic control, although it seems that non-biological processes might also be important for the dissipation of TNT and PETN. Transformation of PETN was also slower during establishment of enrichment culture using pentolite as the sole nitrogen source. In addition, transformation of these explosives was gradually reduced and practically stopped after the forth cultures transfer (80 days). DGGE analysis of bacterial communities from these cultures indicates that all consortia were dominated by bacteria from the order Burkholderiales and Rhodanobacter. In conclusion, our results suggest that PETN might be more persistent than TNT.

Pentaerythritol Tetranitrate (PETN) Surveillance by HPLC-MS: Instrumental Parameters Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, C A; Meissner, R

Surveillance of PETN Homologs in the stockpile here at LLNL is currently carried out by high performance liquid chromatography (HPLC) with ultra violet (UV) detection. Identification of unknown chromatographic peaks with this detection scheme is severely limited. The design agency is aware of the limitations of this methodology and ordered this study to develop instrumental parameters for the use of a currently owned mass spectrometer (MS) as the detection system. The resulting procedure would be a ''drop-in'' replacement for the current surveillance method (ERD04-524). The addition of quadrupole mass spectrometry provides qualitative identification of PETN and its homologs (Petrin, DiPEHN,more » TriPEON, and TetraPEDN) using a LLNL generated database, while providing mass clues to the identity of unknown chromatographic peaks.« less

Number of nitrate groups determines reactivity and potency of organic nitrates: a proof of concept study in ALDH-2−/− mice

PubMed Central

Wenzel, P; Hink, U; Oelze, M; Seeling, A; Isse, T; Bruns, K; Steinhoff, L; Brandt, M; Kleschyov, A L; Schulz, E; Lange, K; Weiner, H; Lehmann, J; Lackner, K J; Kawamoto, T; Münzel, T; Daiber, A

2007-01-01

Background and purpose: Mitochondrial aldehyde dehydrogenase (ALDH-2) has been shown to provide a pathway for bioactivation of organic nitrates and to be prone to desensitization in response to highly potent, but not to less potent, nitrates. We therefore sought to support the hypothesis that bioactivation by ALDH-2 critically depends on the number of nitrate groups within the nitrovasodilator. Experimental approach: Nitrates with one (PEMN), two (PEDN; GDN), three (PETriN; glyceryl trinitrate, GTN) and four (pentaerithrityl tetranitrate, PETN) nitrate groups were investigated. Vasodilatory potency was measured in isometric tension studies using isolated aortic segments of wild type (WT) and ALDH-2−/− mice. Activity of the cGMP-dependent kinase-I (reflected by levels of phosphorylated VAsodilator Stimulated Phosphoprotein, P-VASP) was quantified by Western blot analysis, mitochondrial dehydrogenase activity by HPLC. Following incubation of isolated mitochondria with PETN, PETriN-chromophore and PEDN, metabolites were quantified using chemiluminescence nitrogen detection and mass spectrometry. Key results: Compared to WT, vasorelaxation in response to PETN, PETriN and GTN was attenuated about 10fold in ALDH-2−/− mice, identical to WT vessels preincubated with inhibitors of ALDH-2. Reduced vasodilator potency correlated with reduced P-VASP formation and diminished biotransformation of the tetranitrate- and trinitrate-compounds. None of these findings were observed for PEDN, GDN and PEMN. Conclusions and implications: Our results support the crucial role of ALDH-2 in bioactivating highly reactive nitrates like GTN, PETN and PETriN. ALDH-2-mediated relaxation by organic nitrates therefore depends mainly on the number of nitrate groups. Less potent nitrates like PEDN, GDN and PEMN are apparently biotransformed by other pathways. PMID:17220910

Microenergetic Shock Initiation Studies on Deposited Films of PETN

NASA Astrophysics Data System (ADS)

Tappan, Alexander S.; Wixom, Ryan R.; Trott, Wayne M.; Long, Gregory T.; Knepper, Robert; Brundage, Aaron L.; Jones, David A.

2009-06-01

Films of the high explosive PETN (pentaerythritol tetranitrate) up to 500-μm thick have been deposited through physical vapor deposition, with the intent of creating well-defined samples for shock-initiation studies. PETN films were characterized with surface profilometry, scanning electron microscopy, x-ray diffraction, and focused ion beam nanotomography. These high-density films were subjected to strong shocks in both the in-plane and out-of-plane orientations. Initiation behavior was monitored with high-speed framing and streak camera photography. Direct initiation with a donor explosive (either RDX with binder, or CL-20 with binder) was possible in both orientations, but with the addition of a thin aluminum buffer plate (in-plane configuration only), initiation proved to be difficult due to the attenuated shock and the high density of the PETN films. Mesoscale models of microenergetic samples were created using the shock physics code CTH and compared with experimental results. The results of these experiments will be discussed in the context of small sample geometry, deposited film morphology, and density.

Direct Quantum Mechanical Simulations of Shocked Energetic Materials

DTIC Science & Technology

2008-12-01

dynamics (QMD) simulations of shocked pentaerythritol tetranitrate (PETN), a conventional high explosive , and the polymeric cubic gauche phase of...nitrogen (cg-N), proposed as an environmentally acceptable energetic alternative to conventional explosive formulations. These simulations, made...stored structural potential energy can be liberated quickly enough, it is possible that explosion can occur with energies several orders of magnitude

Microenergetic Shock Initiation Studies on Deposited Films of Petn

NASA Astrophysics Data System (ADS)

Tappan, Alexander S.; Wixom, Ryan R.; Trott, Wayne M.; Long, Gregory T.; Knepper, Robert; Brundage, Aaron L.; Jones, David A.

2009-12-01

Films of the high explosive PETN (pentaerythritol tetranitrate) up to 500-μm thick have been deposited through physical vapor deposition, with the intent of creating well-defined samples for shock-initiation studies. PETN films were characterized with microscopy, x-ray diffraction, and focused ion beam nanotomography. These high-density films were subjected to strong shocks in both the out-of-plane and in-plane orientations. Initiation behavior was monitored with high-speed framing and streak camera photography. Direct initiation with a donor explosive (either RDX with binder, or CL-20 with binder) was possible in both orientations, but with the addition of a thin aluminum buffer plate (in-plane configuration only), initiation proved to be difficult. Initiation was possible with an explosively-driven 0.13-mm thick Kapton flyer and direct observation of initiation behavior was examined using streak camera photography at different flyer velocities. Models of this configuration were created using the shock physics code CTH.

Flying-plate detonator using a high-density high explosive

DOEpatents

Stroud, John R.; Ornellas, Donald L.

1988-01-01

A flying-plate detonator containing a high-density high explosive such as benzotrifuroxan (BTF). The detonator involves the electrical explosion of a thin metal foil which punches out a flyer from a layer overlying the foil, and the flyer striking a high-density explosive pellet of BTF, which is more thermally stable than the conventional detonator using pentaerythritol tetranitrate (PETN).

Quantifying the stability of trace explosives under different environmental conditions using electrospray ionization mass spectrometry.

PubMed

Sisco, Edward; Najarro, Marcela; Samarov, Daniel; Lawrence, Jeffrey

2017-04-01

This work investigates the stability of trace (tens of nanograms) deposits of six explosives: erythritol tetranitrate (ETN), pentaerythritol tetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), and 2,4,6-trinitrophenylmethylnitramine (tetryl) to determine environmental stabilities and lifetimes of trace level materials. Explosives were inkjet printed directly onto substrates and exposed to one of seven environmental conditions (Laboratory, -4°C, 30°C, 47°C, 90% relative humidity, UV light, and ozone) up to 42 days. Throughout the study, samples were extracted and quantified using electrospray ionization mass spectrometry (ESI-MS) to determine the stability of the explosive as a function of time and environmental exposure. Statistical models were then fit to the data and used for pairwise comparisons of the environments. Stability was found to be exposure and compound dependent with minimal sample losses observed for HMX, RDX, and PETN while substantial and rapid losses were observed in all conditions except -4°C for ETN and TNT and in all conditions for tetryl. The results of this work highlight the potential fate of explosive traces when exposed to various environments. Published by Elsevier B.V.

Quantifying the Stability of Trace Explosives under Different Environmental Conditions using Electrospray Ionization Mass Spectrometry

PubMed Central

Sisco, Edward; Najarro, Marcela; Samarov, Daniel; Lawrence, Jeffrey

2017-01-01

This work investigates the stability of trace (tens of nanograms) deposits of six explosives: erythritol tetranitrate (ETN), pentaerythritol tetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), and 2,4,6-trinitrophenylmethylnitramine (tetryl) to determine environmental stabilities and lifetimes of trace level materials. Explosives were inkjet printed directly onto substrates and exposed to one of seven environmental conditions (Laboratory, −4 °C, 30 °C, 47 °C, 90 % relative humidity, UV light, and ozone) up to 42 days. Throughout the study, samples were extracted and quantified using electrospray ionization mass spectrometry (ESI-MS) to determine the stability of the explosive as a function of time and environmental exposure. Statistical models were then fit to the data and used for pairwise comparisons of the environments. Stability was found to be exposure and compound dependent with minimal sample losses observed for HMX, RDX, and PETN while substantial and rapid losses were observed in all conditions except −4 °C for ETN and TNT and in all conditions for tetryl. The results of this work highlight the potential fate of explosive traces when exposed to various environments. PMID:28153227

Surface Chemistry of a Microcoated Energetic Material, Pentaerythritoltetranitrate (PETN)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worley, C.M.; Vannet, M.D.; Ball, G.L.

1987-01-01

A microcoating technique was used to apply a polymer to an energetic explosive material. The explosive was pentaerythritoltetranitrate (PETN), and the coating was a copolymer consisting of vinylchloride/trifluorochloroethylene in a 1.5/1.0 molecular ratio. X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) were used to study the surface and interfacial chemistry of PETN powders and pellets made from compressed powders having either 0.5 or 20 wt% coating. Two simple models were used to discuss the nature of the copolymer film on the PETN. Model I shows the copolymer completely coating PETN; Model II depicts the copolymer as only partially coveringmore » PETN. Model II was applicable in explaining the 0.5 and 20 wt% microcoating of powders, as well as the 0.5 wt% coated pellets. However, the pellets with 20 wt% coating showed the copolymer to completely coat PETN (Model I), suggesting copolymer redistribution during pelletization. XPS and ISS results showed the copolymer film to be thin. An XPS expression modified to accommodate ISS data was developed for the calculation of the average copolymer thickness of PETN. The thicknesses were determined to be 10 {angstrom} and 6 {angstrom} for 0.5 wt% coated PETN powders and pellets, respectively. Bonding between the copolymer and PETN was concluded to be mechanical.« less

Initiation of insensitive explosives by laser energy

NASA Technical Reports Server (NTRS)

Menichelli, V. J.; Yang, L. C.

1972-01-01

Instantaneous longitudinal detonations were observed in confined columns of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and tetryl when these materials were pulsed with light energy from a focused Q-switch ruby laser. The laser energy ranged from 0.5 to 4.2 J with a pulse width of 25 ns. Enhancement of the ignition mechanism is hypothesized when a 100-nm (1000-A) thick aluminum film is vacuum-deposited on the explosive side of the window. Upon irradiation from the laser, a shock is generated at the aluminum explosive interface. Steady state detonations can be reached in less than 0.5 microseconds with less than 10% variation in detonation velocity for PETN and RDX.

Spatiotemporal temperature and density characterization of high-power atmospheric flashover discharges over inert poly(methyl methacrylate) and energetic pentaerythritol tetranitrate dielectric surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, V.; Grant, C. D.; McCarrick, J. F.

2012-03-01

A flashover arc source that delivered up to 200 mJ on the 100s-of-ns time-scale to the arc and a user-selected dielectric surface was characterized for studying high-explosive kinetics under plasma conditions. The flashover was driven over thin pentaerythritol tetranitrate (PETN) and poly(methyl methacrylate) (PMMA) dielectric films and the resultant plasma was characterized in detail. Time- and space-resolved temperatures and electron densities of the plasma were obtained using atomic emission spectroscopy. The hydrodynamics of the plasma was captured through fast, visible imaging. Fourier transform infrared spectroscopy (FTIR) was used to characterize the films pre- and post-shot for any chemical alterations. Time-resolvedmore » infrared spectroscopy (TRIR) provided PETN depletion data during the plasma discharge. For both types of films, temperatures of 1.6-1.7 eV and electron densities of {approx}7-8 x 10{sup 17}/cm{sup 3}{approx}570 ns after the start of the discharge were observed with temperatures of 0.6-0.7 eV persisting out to 15 {mu}s. At 1.2 {mu}s, spatial characterization showed flat temperature and density profiles of 1.1-1.3 eV and 2-2.8 x 10{sup 17}/cm{sup 3} for PETN and PMMA films, respectively. Images of the plasma showed an expanding hot kernel starting from radii of {approx}0.2 mm at {approx}50 ns and reaching {approx}1.1 mm at {approx}600 ns. The thin films ablated or reacted several hundred nm of material in response to the discharge. First TRIR data showing the in situ reaction or depletion of PETN in response to the flashover arc were successfully obtained, and a 2-{mu}s, 1/e decay constant was measured. Preliminary 1 D simulations compared reasonably well with the experimentally determined plasma radii and temperatures. These results complete the first steps to resolving arc-driven PETN reaction pathways and their associated kinetic rates using in situ spectroscopy techniques.« less

Size and habit evolution of PETN crystals - a lattice Monte Carlo study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zepeda-Ruiz, L A; Maiti, A; Gee, R

2006-02-28

Starting from an accurate inter-atomic potential we develop a simple scheme of generating an ''on-lattice'' molecular potential of short range, which is then incorporated into a lattice Monte Carlo code for simulating size and shape evolution of nanocrystallites. As a specific example, we test such a procedure on the morphological evolution of a molecular crystal of interest to us, e.g., Pentaerythritol Tetranitrate, or PETN, and obtain realistic facetted structures in excellent agreement with experimental morphologies. We investigate several interesting effects including, the evolution of the initial shape of a ''seed'' to an equilibrium configuration, and the variation of growth morphologymore » as a function of the rate of particle addition relative to diffusion.« less

Benchtop Energetics Progress

DTIC Science & Technology

2011-07-01

sensitivity. We employ direct laser irradiation, and indirect laser-driven shock, techniques to initiate thin-film explosive samples contained in a...energetic events in a few minutes. 14. ABSTRACT A detonation wave passing through an organic explosive , such as pentaerythritol tetranitrate (PETN...C5H4N4O12), is remarkably efficient in converting the solid explosive into final thermodynamically-stable gaseous products (e.g. N2, CO2, H2O

Photoactive high explosives: linear and nonlinear photochemistry of petrin tetrazine chloride.

PubMed

Greenfield, Margo T; McGrane, Shawn D; Bolme, Cindy A; Bjorgaard, Josiah A; Nelson, Tammie R; Tretiak, Sergei; Scharff, R Jason

2015-05-21

Pentaerythritol tetranitrate (PETN), a high explosive, initiates with traditional shock and thermal mechanisms. In this study, the tetrazine-substituted derivative of PETN, pentaerythritol trinitrate chlorotetrazine (PetrinTzCl), is being investigated for a photochemical initiation mechanism that could allow control over the chemistry contributing to decomposition leading to initiation. PetrinTzCl exhibits a photochemical quantum yield (QYPC) at 532 nm not evident with PETN. Using static spectroscopic methods, we observe energy absorption on the tetrazine (Tz) ring that results in photodissociation yielding N2, Cl-CN, and Petrin-CN as the major photoproducts. The QYPC was enhanced with increasing irradiation intensity. Experiment and theoretical calculations imply this excitation mechanism follows sequential photon absorption. Dynamic simulations demonstrate that the relaxation mechanism leading to the observed photochemistry in PetrinTzCl is due to vibrational excitation during internal conversion. PetrinTzCl's single photon stability and intensity dependence suggest this material could be stable in ambient lighting, yet possible to initiate with short-pulsed lasers.

High explosive spot test analyses of samples from Operable Unit (OU) 1111

DOE Office of Scientific and Technical Information (OSTI.GOV)

McRae, D.; Haywood, W.; Powell, J.

1995-01-01

A preliminary evaluation has been completed of environmental contaminants at selected sites within the Group DX-10 (formally Group M-7) area. Soil samples taken from specific locations at this detonator facility were analyzed for harmful metals and screened for explosives. A sanitary outflow, a burn pit, a pentaerythritol tetranitrate (PETN) production outflow field, an active firing chamber, an inactive firing chamber, and a leach field were sampled. Energy dispersive x-ray fluorescence (EDXRF) was used to obtain semi-quantitative concentrations of metals in the soil. Two field spot-test kits for explosives were used to assess the presence of energetic materials in the soilmore » and in items found at the areas tested. PETN is the major explosive in detonators manufactured and destroyed at Los Alamos. No measurable amounts of PETN or other explosives were detected in the soil, but items taken from the burn area and a high-energy explosive (HE)/chemical sump were contaminated. The concentrations of lead, mercury, and uranium are given.« less

First-Principles Studies of Pentaerythritol Tetranitrate (PETN) Single Crystal Unit Cell Volumes and Vibrational Frequencies under Hydrostatic Pressure

NASA Astrophysics Data System (ADS)

Perger, Warren F.; Zhao, Jijun; Winey, J. M.; Gupta, Y. M.

2006-07-01

The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used. The pressure-induced shift of the vibrational frequencies is presented.

Detection of explosives by positive corona discharge ion mobility spectrometry.

PubMed

Tabrizchi, Mahmoud; Ilbeigi, Vahideh

2010-04-15

In this work, thermal decomposition has been used to detect explosives by IMS in positive polarity. Explosives including Pentaerythritol Tetranitrate (PETN), Cyclo-1,3,5-Trimethylene-2,4,6-Trinitramine (RDX), 2,4,6-Trinitrotoluene (TNT), 2,4-Dihydro-5-nitro-3H-1,2,4-triazol-3-one (NTO), 1,3,5,7-Tetranitro-1,3,5,7-tetrazocine (HMX), have been evaluated at temperatures between 150 and 250 degrees C in positive polarity in air. Explosives yield NO(x) which causes NO(+) peak to increase. Additional peaks may be used to identify the type of explosive. The limit of detection for RDX, HMX, PETN, NTO, and TNT were obtained to be 1, 10, 40, 1000, and 1000 ng, respectively. 2009 Elsevier B.V. All rights reserved.

Modeling physical vapor deposition of energetic materials

DOE PAGES

Shirvan, Koroush; Forrest, Eric C.

2018-03-28

Morphology and microstructure of organic explosive films formed using physical vapor deposition (PVD) processes strongly depends on local surface temperature during deposition. Currently, there is no accurate means of quantifying the local surface temperature during PVD processes in the deposition chambers. This study focuses on using a multiphysics computational fluid dynamics tool, STARCCM+, to simulate pentaerythritol tetranitrate (PETN) deposition. The PETN vapor and solid phase were simulated using the volume of fluid method and its deposition in the vacuum chamber on spinning silicon wafers was modeled. The model also included the spinning copper cooling block where the wafers are placedmore » along with the chiller operating with forced convection refrigerant. Implicit time-dependent simulations in two- and three-dimensional were performed to derive insights in the governing physics for PETN thin film formation. PETN is deposited at the rate of 14 nm/s at 142.9 °C on a wafer with an initial temperature of 22 °C. The deposition of PETN on the wafers was calculated at an assumed heat transfer coefficient (HTC) of 400 W/m 2 K. This HTC proved to be the most sensitive parameter in determining the local surface temperature during deposition. Previous experimental work found noticeable microstructural changes with 0.5 mm fused silica wafers in place of silicon during the PETN deposition. This work showed that fused silica slows initial wafer cool down and results in ~10 °C difference for the surface temperature at 500 μm PETN film thickness. It was also found that the deposition surface temperature is insensitive to the cooling power of the copper block due to the copper block's very large heat capacity and thermal conductivity relative to the heat input from the PVD process. Future work should incorporate the addition of local stress during PETN deposition. Lastly, based on simulation results, it is also recommended to investigate the impact of wafer surface energy on the PETN microstructure and morphology formation.« less

Modeling physical vapor deposition of energetic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shirvan, Koroush; Forrest, Eric C.

Morphology and microstructure of organic explosive films formed using physical vapor deposition (PVD) processes strongly depends on local surface temperature during deposition. Currently, there is no accurate means of quantifying the local surface temperature during PVD processes in the deposition chambers. This study focuses on using a multiphysics computational fluid dynamics tool, STARCCM+, to simulate pentaerythritol tetranitrate (PETN) deposition. The PETN vapor and solid phase were simulated using the volume of fluid method and its deposition in the vacuum chamber on spinning silicon wafers was modeled. The model also included the spinning copper cooling block where the wafers are placedmore » along with the chiller operating with forced convection refrigerant. Implicit time-dependent simulations in two- and three-dimensional were performed to derive insights in the governing physics for PETN thin film formation. PETN is deposited at the rate of 14 nm/s at 142.9 °C on a wafer with an initial temperature of 22 °C. The deposition of PETN on the wafers was calculated at an assumed heat transfer coefficient (HTC) of 400 W/m 2 K. This HTC proved to be the most sensitive parameter in determining the local surface temperature during deposition. Previous experimental work found noticeable microstructural changes with 0.5 mm fused silica wafers in place of silicon during the PETN deposition. This work showed that fused silica slows initial wafer cool down and results in ~10 °C difference for the surface temperature at 500 μm PETN film thickness. It was also found that the deposition surface temperature is insensitive to the cooling power of the copper block due to the copper block's very large heat capacity and thermal conductivity relative to the heat input from the PVD process. Future work should incorporate the addition of local stress during PETN deposition. Lastly, based on simulation results, it is also recommended to investigate the impact of wafer surface energy on the PETN microstructure and morphology formation.« less

New Outlook on the High-Pressure Behavior of Pentaerythritol Tetranitrate

DTIC Science & Technology

2007-09-01

energetic materials, such as Octahydro-1, 3, 5, 7-tetranitro- 1, 3, 5, 7-tetrazocine ( HMX ) and RDX , and this phenomenon is most likely caused by...H.; Smith, L. C. Studies on the Polymorphs of HMX . Los Alamos Technical Report No. LAMS-2652, 1962. 2. Halleck, P. M.; Wackerle, J. Dynamic...429, 827. 10. Sorescu, D. C.; Rice, B. M.; Thompson, D. L. Theoretical Studies of the Hydrostatic Compression of RDX , HMX , HNIW, and PETN Crystals

Non-hemodynamic effects of organic nitrates and the distinctive characteristics of pentaerithrityl tetranitrate.

PubMed

Gori, Tommaso; Daiber, Andreas

2009-01-01

Organic nitrates are among the oldest and yet most commonly employed drugs in the long-term therapy of coronary artery disease and congestive heart failure. While they have long been used in clinical practice, our understanding of their mechanism of action and side effects remains incomplete. For instance, recent findings provide evidence of previously unanticipated, non-hemodynamic properties that include potentially beneficial mechanisms (such as the induction of a protective phenotype that mimics ischemic preconditioning), but also toxic effects (such as endothelial and autonomic dysfunction, rebound angina, tolerance). To date, the most commonly employed organic nitrates are isosorbide mononitrate, isosorbide dinitrate, and nitroglycerin (glyceryl trinitrate). Another organic nitrate, pentaerithrityl tetranitrate (PETN), has long been employed in eastern European countries and is currently being reintroduced in Western countries. In light of their wide use, and of the (re)introduction of PETN in Western markets, the present review focuses on the novel effects of organic nitrates, describing their potential clinical implications and discussing differences among different compounds. We believe that these recent findings have important clinical implications. Since the side effects of organic nitrates such as nitroglycerin and isosorbides appear to be mediated by reactive oxygen species, care should be taken that drugs with antioxidant properties are co-administered. On the other hand, efforts should be made to clinically exploit the preconditioning effects of these drugs.

Ultraviolet Raman Wide-Field Hyperspectral Imaging Spectrometer for Standoff Trace Explosive Detection.

PubMed

Hufziger, Kyle T; Bykov, Sergei V; Asher, Sanford A

2017-02-01

We constructed the first deep ultraviolet (UV) Raman standoff wide-field imaging spectrometer. Our novel deep UV imaging spectrometer utilizes a photonic crystal to select Raman spectral regions for detection. The photonic crystal is composed of highly charged, monodisperse 35.5 ± 2.9 nm silica nanoparticles that self-assemble in solution to produce a face centered cubic crystalline colloidal array that Bragg diffracts a narrow ∼1.0 nm full width at half-maximum (FWHM) UV spectral region. We utilize this photonic crystal to select and image two different spectral regions containing resonance Raman bands of pentaerythritol tetranitrate (PETN) and NH 4 NO 3 (AN). These two deep UV Raman spectral regions diffracted were selected by angle tuning the photonic crystal. We utilized this imaging spectrometer to measure 229 nm excited UV Raman images containing ∼10-1000 µg/cm 2 samples of solid PETN and AN on aluminum surfaces at 2.3 m standoff distances. We estimate detection limits of ∼1 µg/cm 2 for PETN and AN films under these experimental conditions.

General Chemistry Division. Quarterly report, July--September 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrar, J.E.

1978-11-17

Status of the following studies is given: nonaqueous titrimetry; molar absorbance of 1,3,5,-triamine-2,4,6,-trinitrobenzene in dimethylsulfoxide, potentiometric microdetermination of pentaerythritol tetranitrate (PETN) in PETN-containing composites; potentiometric semimicrodetermination of some tetrazoles with silver nitrate; applications of a mode-locked krypton ion laser; time-resolved spectroscopy; photoelectrochemistry; evaluation of a prototype atomic emission source system; laser spectroscopy of neptunium; high-performance liquid chromatography of polyphenyl ether; acquisition of a portable, computerized mass spectrometer; improved inlet for quantitative mass spectrometry; a computer data system for the UTI gas analyzers; analysis of perfluorobutene-2; examination of iridium coatings; source of high-intensity, polarized x rays for fluorescence analysis; mass spectrometermore » for the coal gasification field test; materials protection measurement guides; the LOG system of sample file control; and methylation of platinum compounds by methylcobalamin. (LK)« less

Detonation Reaction Zones in Condensed Explosives

NASA Astrophysics Data System (ADS)

Tarver, Craig M.

2006-07-01

Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich - von Neumann - Doling (NEZND) theory and Ignition and Growth reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes are discussed for explosives based on pentaerythritol tetranitrate (PETN), nitromethane, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), triaminitrinitrobenzene(TATB) and trinitrotoluene (TNT).

Examining the Chemical and Structural Properties that Influence the Sensitivity of Energetic Nitrate Esters

DOE PAGES

Manner, Virginia W.; Cawkwell, Marc; Kober, Edward M.; ...

2018-03-09

The sensitivity of explosives is controlled by factors that span from intrinsic chemical reactivity and chemical intramolecular effects to mesoscale structure and defects, and has been a topic of extensive study for over 50 years. Due to these complex competing chemical and physical elements, a unifying relationship between molecular framework, crystal structure, and sensitivity has yet to be developed. In order to move towards this goal, ideally experimental studies should be performed on systems with small, systematic structural modifications, with modeling utilized to interpret experimental results. Pentaerythritol tetranitrate (PETN) is a common nitrate ester explosive that has been widely studiedmore » due to its use in military and commercial explosives. We have synthesized PETN derivatives with modified sensitivity characteristics by substituting the CCH 2ONO 2 moiety with other substituents, including CH, CNH 2, CNH3X, CCH 3, and PO. We relate the handling sensitivity properties of each PETN derivative to its structural properties, and discuss the potential roles of thermodynamic properties such as heat capacity and heat of formation, thermal stability, crystal structure, compressibility, and inter- and intramolecular hydrogen bonding on impact sensitivity. Reactive molecular dynamics (MD) simulations of the C/H/N/O-based PETN-derivatives have been performed under cook-off conditions that mimic those accessed in impact tests. These simulations infer how changes in chemistry affect the subsequent decomposition pathways.« less

Examining the Chemical and Structural Properties that Influence the Sensitivity of Energetic Nitrate Esters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manner, Virginia W.; Cawkwell, Marc; Kober, Edward M.

The sensitivity of explosives is controlled by factors that span from intrinsic chemical reactivity and chemical intramolecular effects to mesoscale structure and defects, and has been a topic of extensive study for over 50 years. Due to these complex competing chemical and physical elements, a unifying relationship between molecular framework, crystal structure, and sensitivity has yet to be developed. In order to move towards this goal, ideally experimental studies should be performed on systems with small, systematic structural modifications, with modeling utilized to interpret experimental results. Pentaerythritol tetranitrate (PETN) is a common nitrate ester explosive that has been widely studiedmore » due to its use in military and commercial explosives. We have synthesized PETN derivatives with modified sensitivity characteristics by substituting the CCH 2ONO 2 moiety with other substituents, including CH, CNH 2, CNH3X, CCH 3, and PO. We relate the handling sensitivity properties of each PETN derivative to its structural properties, and discuss the potential roles of thermodynamic properties such as heat capacity and heat of formation, thermal stability, crystal structure, compressibility, and inter- and intramolecular hydrogen bonding on impact sensitivity. Reactive molecular dynamics (MD) simulations of the C/H/N/O-based PETN-derivatives have been performed under cook-off conditions that mimic those accessed in impact tests. These simulations infer how changes in chemistry affect the subsequent decomposition pathways.« less

Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor

PubMed Central

Wang, Chen; Huang, Helin; Bunes, Benjamin R.; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

2016-01-01

1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2+) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and 1H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection. PMID:27146290

Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor.

PubMed

Wang, Chen; Huang, Helin; Bunes, Benjamin R; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

2016-05-05

1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2(+)) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and (1)H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection.

Reactive Burn Model Calibration for PETN Using Ultra-High-Speed Phase Contrast Imaging

NASA Astrophysics Data System (ADS)

Johnson, Carl; Ramos, Kyle; Bolme, Cindy; Sanchez, Nathaniel; Barber, John; Montgomery, David

2017-06-01

A 1D reactive burn model (RBM) calibration for a plastic bonded high explosive (HE) requires run-to-detonation data. In PETN (pentaerythritol tetranitrate, 1.65 g/cc) the shock to detonation transition (SDT) is on the order of a few millimeters. This rapid SDT imposes experimental length scales that preclude application of traditional calibration methods such as embedded electromagnetic gauge methods (EEGM) which are very effective when used to study 10 - 20 mm thick HE specimens. In recent work at Argonne National Laboratory's Advanced Photon Source we have obtained run-to-detonation data in PETN using ultra-high-speed dynamic phase contrast imaging (PCI). A reactive burn model calibration valid for 1D shock waves is obtained using density profiles spanning the transition to detonation as opposed to particle velocity profiles from EEGM. Particle swarm optimization (PSO) methods were used to operate the LANL hydrocode FLAG iteratively to refine SURF RBM parameters until a suitable parameter set attained. These methods will be presented along with model validation simulations. The novel method described is generally applicable to `sensitive' energetic materials particularly those with areal densities amenable to radiography.

Thermochemical properties of nanometer CL-20 and PETN fabricated using a mechanical milling method

NASA Astrophysics Data System (ADS)

Song, Xiaolan; Wang, Yi; An, Chongwei

2018-06-01

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and pentaerythritol tetranitrate (PETN), with mean sizes of 73.8 nm and 267.7 nm, respectively, were fabricated on a high-energy ball-mill. Scanning electron microscope (SEM) analysis was used to image the micron-scale morphology of nano-explosives, and the particle size distribution was calculated using the statistics of individual particle sizes obtained from the SEM images. Analyses, such as X-ray diffractometer (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), were also used to confirm whether the crystal phase, molecular structure, and surface elements changed after a long-term milling process. The results were as expected. Thermal analysis was performed at different heating rates. Parameters, such as the activation energy (ES), activation enthalpy (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), and critical temperature of thermal explosion (Tb), were calculated to determine the decomposition courses of the explosives. Moreover, the thermal decomposition mechanisms of nano CL-20 and nano PETN were investigated using thermal-infrared spectrometry online (DSC-IR) analysis, by which their gas products were also detected. The results indicated that nano CL-20 decomposed to CO2 and N2O and that nano PETN decayed to NO2, which implied a remarkable difference between the decomposition mechanisms of the two explosives. In addition, the mechanical sensitivities of CL-20 and PETN were tested, and the results revealed that nano-explosives were more insensitive than raw ones, and the possible mechanism for this was discussed. Thermal sensitivity was also investigated with a 5 s bursting point test, from which the 5 s bursting point (T5s) and the activation of the deflagration were obtained.

Heme Oxygenase-1 Induction and Organic Nitrate Therapy: Beneficial Effects on Endothelial Dysfunction, Nitrate Tolerance, and Vascular Oxidative Stress

PubMed Central

Daiber, Andreas; Oelze, Matthias; Wenzel, Philip; Bollmann, Franziska; Pautz, Andrea; Kleinert, Hartmut

2012-01-01

Organic nitrates are a group of very effective anti-ischemic drugs. They are used for the treatment of patients with stable angina, acute myocardial infarction, and chronic congestive heart failure. A major therapeutic limitation inherent to organic nitrates is the development of tolerance, which occurs during chronic treatment with these agents, and this phenomenon is largely based on induction of oxidative stress with subsequent endothelial dysfunction. We therefore speculated that induction of heme oxygenase-1 (HO-1) could be an efficient strategy to overcome nitrate tolerance and the associated side effects. Indeed, we found that hemin cotreatment prevented the development of nitrate tolerance and vascular oxidative stress in response to chronic nitroglycerin therapy. Vice versa, pentaerithrityl tetranitrate (PETN), a nitrate that was previously reported to be devoid of adverse side effects, displayed tolerance and oxidative stress when the HO-1 pathway was blocked pharmacologically or genetically by using HO-1+/– mice. Recently, we identified activation of Nrf2 and HuR as a principle mechanism of HO-1 induction by PETN. With the present paper, we present and discuss our recent and previous findings on the role of HO-1 for the prevention of nitroglycerin-induced nitrate tolerance and for the beneficial effects of PETN therapy. PMID:22506100

Long-term use of short- and long-acting nitrates in stable angina pectoris.

PubMed

Kosmicki, Marek Antoni

2009-05-01

Long-acting nitrates are effective antianginal drugs during initial treatment. However, their therapeutic value is compromised by the rapid development of tolerance during sustained therapy, which means that their clinical efficacy is decreased during long-term use. Sublingual nitroglycerin (NTG), a short-acting nitrate, is suitable for the immediate relief of angina. In patients with stable angina treated with oral long-acting nitrates, NTG maintains its full anti-ischemic effect both after initial oral ingestion and after intermittent long-term oral administration. However, NTG attenuates this effect during continuous treatment, when tolerance to oral nitrates occurs, and this is called cross-tolerance. In stable angina long-acting nitrates are considered third-line therapy because a nitrate-free interval is required to avoid the development of tolerance. Nitrates vary in their potential to induce the development of tolerance. During long-lasting nitrate therapy, except pentaerythritol tetranitrate (PETN), one can observe the development of reactive oxygen species (ROS) inside the muscular cell of a vessel wall, and these bind with nitric oxide (NO). This leads to decreased NO activity, thus, nitrate tolerance. PETN has no tendency to form ROS, and therefore during long-term PETN therapy, there is probably no tolerance or cross-tolerance, as during treatment with other nitrates.

Micron-scale Reactive Atomistic Simulation of Void Collapse and Hotspot Growth in PETN

NASA Astrophysics Data System (ADS)

Thompson, Aidan; Shan, Tzu-Ray; Wixom, Ryan

2015-06-01

Material defects and other heterogeneities such as dislocations, micro-porosity, and grain boundaries play key roles in the shock-induced initiation of detonation in energetic materials. We performed non-equilibrium molecular dynamics simulations to explore the effect of nanoscale voids on hotspot growth and initiation in micron-scale pentaerythritol tetranitrate (PETN) crystals under weak shock loading (Up = 1.25 km/s; Us = 4.5 km/s). We used the ReaxFF potential implemented in LAMMPS. We built a pseudo-2D PETN crystal with dimensions 0.3 μm × 0.22 μm × 1.3 nm containing a 20 nm cylindrical void. Once the initial shockwave traversed the entire sample, the shock-front absorbing boundary condition was applied, allowing the simulation to continue beyond 1 nanosecond. Results show an exponentially increasing hotspot growth rate. The hotspot morphology is initially symmetric about the void axis, but strong asymmetry develops at later times, due to strong coupling between exothermic chemistry, temperature, and divergent secondary shockwaves emanating from the collapsing void. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Secondary electrospray ionization-ion mobility spectrometry for explosive vapor detection.

PubMed

Tam, Maggie; Hill, Herbert H

2004-05-15

The unique capability of secondary electrospray ionization (SESI) as a nonradioactive ionization source to detect analytes in both liquid and gaseous samples was evaluated using aqueous solutions of three common military explosives: cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), nitroglycerin (NG) and pentaerythritol tetranitrate (PETN). The adducts formed between the compounds and their respective dissociation product, RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-), gave the most intense signal for the individual compound but were more sensitive to temperature than other species. These autoadducts were identified as RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-) and had maximum signal intensity at 137, 100, and 125 degrees C, respectively. The reduced mobility values of the three compounds were constant over the temperature range from 75 to 225 degrees C. The signal-to-noise ratios for RDX, NG, and PETN at 50 mg L(-1) in methanol-water were 340, 270, and 170, respectively, with a nominal noise of 8 +/- 2 pA. In addition to the investigation of autoadduct formation, the concept of doping the ionization source with nonvolatile adduct-forming agents was investigated and described for the first time. The SESI-IMS detection limit for RDX was 116 microg L(-1) in the presence of a traditional volatile chloride dopant and 5.30 microg L(-1) in the presence of a nonvolatile nitrate dopant. In addition to a lower detection limit, the nitrate dopant also produced a greater response sensitivity and a higher limit of linearity than did the traditional volatile chloride dopant.

A systematic tandem mass spectrometric study of anion attachment for improved detection and acidity evaluation of nitrogen-rich energetic compounds.

PubMed

Gaiffe, Gabriel; Bridoux, Maxime C; Costanza, Christine; Cole, Richard B

2018-01-01

The development of rapid, efficient, and reliable detection methods for the characterization of energetic compounds is of high importance to security forces concerned with terrorist threats. With a mass spectrometric approach, characteristic ions can be produced by attaching anions to analyte molecules in the negative ion mode of electrospray ionization mass spectrometry (ESI-MS). Under optimized conditions, formed anionic adducts can be detected with higher sensitivities as compared with the deprotonated molecules. Fundamental aspects pertaining to the formation of anionic adducts of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), 1,3,5-trinitro-1,3,5-triazinane (RDX), pentaerythritol tetranitrate (PETN), nitroglycerin (NG), and 1,3,5-trinitroso-1,3,5-triazinane energetic (R-salt) compounds using various anions have been systematically studied by ESI-MS and ESI tandem mass spectrometry (collision-induced dissociation) experiments. Bracketing method results show that the gas-phase acidities of PETN, RDX, and HMX fall between those of HF and acetic acid. Moreover, PETN and RDX are each less acidic than HMX in the gas phase. Nitroglycerin was found to be the most acidic among the nitrogen-rich explosives studied. The ensemble of bracketing results allows the construction of the following ranking of gas-phase acidities: PETN (1530-1458 kJ/mol) > RDX (approximately 1458 kJ/mol) > HMX (approximately 1433 kJ/mol) > nitroglycerin (1427-1327.8 kJ/mol). Copyright © 2017 John Wiley & Sons, Ltd.

Integrated Data Collection Analysis (IDCA) Program — Bullseye ® Smokeless Powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

2013-05-30

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of Bullseye ® smokeless powder (Gunpowder). The participants found the Gunpowder: 1) to have a range of sensitivity to impact, from less than RDX to almost as sensitive as PETN, 2) to be moderately sensitive to BAM and ABL friction, 3) have a range for ESD, from insensitive to more sensitive than PETN, and 4) to have thermal sensitivity about themore » same as PETN and RDX.« less

The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Audrey Noreen

2006-01-01

Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle (~1 pg) without the need formore » consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA simulants using one set of operational conditions is established.« less

Novel uses of detonator diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, John R.; Wilde, Zakary Robert; Tasker, Douglas George

A novel combination of diagnostics is being used to research the physics of detonator initiation. The explosive PETN (Pentaerythritol tetranitrate) commonly used in detonators, is also a piezo-electric material that, when sufficiently shocked, emits an electromagnetic field in the radio frequency (RF) range, along crystal fracture planes. In an effort to capture this RF signal, a new diagnostic was created. A copper foil, used as an RF antenna, was wrapped around a foam fixture encompassing a PETN pellet. Rogowski coils were used to obtain the change in current with respect to time (di/dt) the detonator circuit, in and polyvinylidene difluoridemore » (PVDF) stress sensors were used to capture shockwave arrival time. The goal of these experiments is to use these diagnostics to study the reaction response of a PETN pellet of known particle size to shock loading with various diagnostics including an antenna to capture RF emissions. Our hypothesis is that RF feedback may signify the rate of deflagration to detonation transition (DDT) or lack thereof. The new diagnostics and methods will be used to determine the timing of start of current, bridge burst, detonator breakout timing and RF generated from detonation. These data will be compared to those of currently used diagnostics in order to validate the accuracy of these new methods. Future experiments will incorporate other methods of validation including dynamic radiography, optical initiation and use of magnetic field sensors.« less

Shock initiation of explosives: High temperature hot spots explained

NASA Astrophysics Data System (ADS)

Bassett, Will P.; Johnson, Belinda P.; Neelakantan, Nitin K.; Suslick, Kenneth S.; Dlott, Dana D.

2017-08-01

We investigated the shock initiation of energetic materials with a tabletop apparatus that uses km s-1 laser-driven flyer plates to initiate tiny explosive charges and obtains complete temperature histories with a high dynamic range. By comparing various microstructured formulations, including a pentaerythritol tetranitrate (PETN) based plastic explosive (PBX) denoted XTX-8003, we determined that micron-scale pores were needed to create high hot spot temperatures. In charges where micropores (i.e., micron-sized pores) were present, a hot spot temperature of 6000 K was observed; when the micropores were pre-compressed to nm scale, however, the hot spot temperature dropped to ˜4000 K. By comparing XTX-8003 with an analog that replaced PETN by nonvolatile silica, we showed that the high temperatures require gas in the pores, that the high temperatures were created by adiabatic gas compression, and that the temperatures observed can be controlled by the choice of ambient gases. The hot spots persist in shock-compressed PBXs even in vacuum because the initially empty pores became filled with gas created in-situ by shock-induced chemical decomposition.

Time-of-flight mass spectrometry of laser exploding foil initiated PETN samples

NASA Astrophysics Data System (ADS)

Fajardo, Mario E.; Molek, Christopher D.; Fossum, Emily C.

2017-01-01

We report the results of time-of-flight mass spectrometry (TOFMS) measurements of the gaseous products of thin-film pentaerythritol tetranitrate [PETN, C(CH2NO3)4] samples reacting in vacuo. The PETN sample spots are produced by masked physical vapor deposition [A.S. Tappan, et al., AIP Conf. Proc. 1426, 677 (2012)] onto a first-surface aluminum mirror. A pulsed laser beam imaged through the soda lime glass mirror substrate converts the aluminum layer into a high-temperature high-pressure plasma which initiates chemical reactions in the overlying PETN sample. We had previously proposed [E.C. Fossum, et al., AIP Conf. Proc. 1426, 235 (2012)] to exploit differences in gaseous product chemical identities and molecular velocities to provide a chemically-based diagnostic for distinguishing between "detonation-like" and deflagration responses. Briefly: we expect in-vacuum detonations to produce hyperthermal (v˜10 km/s) thermodynamically-stable products such as N2, CO2, and H2O, and for deflagrations to produce mostly reaction intermediates, such as NO and NO2, with much slower molecular velocities - consistent with the expansion-quenched thermal decomposition of PETN. We observe primarily slow reaction intermediates (NO2, CH2NO3) at low laser pulse energies, the appearance of NO at intermediate laser pulse energies, and the appearance of hyperthemal CO/N2 at mass 28 amu at the highest laser pulse energies. However, these results are somewhat ambiguous, as the NO, NO2, and CH2NO3 intermediates persist and all species become hyperthermal at the higher laser pulse energies. Also, the purported CO/N2 signal at 28 amu may be contaminated by silicon ablated from the glass mirror substrate. We plan to mitigate these problems in future experiments by adopting the "Buelow" sample configuration which employs an intermediate foil barrier to shield the energetic material from the laser and the laser driven plasma [S.J. Buelow, et al., AIP Conf. Proc. 706, 1377 (2003)].

Analytical Characterization of Erythritol Tetranitrate, an Improvised Explosive.

PubMed

Matyáš, Robert; Lyčka, Antonín; Jirásko, Robert; Jakový, Zdeněk; Maixner, Jaroslav; Mišková, Linda; Künzel, Martin

2016-05-01

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [(15) N4 ] tetranitrate. In the case of powder diffraction, recently published data were verified, and (1) H, (13) C, and (15) N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories. © 2016 American Academy of Forensic Sciences.

The Characterization of a Slurry Explosive--Teledet

DTIC Science & Technology

1979-02-01

weight PETN* 38.0 + .5 Ammonium nitrate** 27 T .5 Diethyleneglycol 9 T .5 Guar Gum .5 Water 25 + .5 *This is ultra-fine particle size, sensitive PETN. r...Diamond Laboratories ATTN: Technical Library I Branch 420, Mr. R.K. Warner 2800 Powder Mill Road Adelphi, MD 20783 P Commander US Army Engineers

Defect states at organic-inorganic interfaces: Insight from first principles calculations for pentaerythritol tetranitrate on MgO surface

NASA Astrophysics Data System (ADS)

Tsyshevsky, Roman V.; Rashkeev, Sergey N.; Kuklja, Maija M.

2015-07-01

Light-responsive organic-inorganic interfaces offer experimental opportunities that are otherwise difficult to achieve. Since laser light can be manipulated very precisely, it becomes possible to engineer selective, predictive, and highly controlled interface properties. Photochemistry of organic-inorganic energetic interfaces is a rapidly emerging research field in which energy absorption and interface stability mechanisms have yet to be established. To explore the interaction of the laser irradiation with molecular materials, we performed first principle calculations of a prototype organic-inorganic interface between a nitroester (pentaerythritol tetranitrate, PETN, C5H8N4O12) and a magnesium oxide (MgO) surface. We found that the light absorption is defined by the band alignment between interface components and interfacial charge transfer coupled with electronic states in the band gap, generated by oxide surface defects. Hence the choice of an oxide substrate and its morphology makes the optical absorption tunable and governs both the energy accumulation and energy release at the interface. The obtained results offer a possible consistent interpretation of experiments on selective laser initiation of energetic materials, which reported that the presence of metal oxide additives triggered the photoinitiation by excitation energy much lower than the band gap. We suggest that PETN photodecomposition is catalyzed by oxygen vacancies (F0 centers) at the MgO surface. Our conclusions predict ways for a complete separation of thermo- and photo-stimulated interface chemistry of molecular materials, which is imperative for highly controllable fast decomposition and was not attainable before. The methodology described here can be applied to any type of molecular material/wide band gap dielectric interfaces. It provides a solid basis for novel design and targeted improvements of organic-inorganic interfaces with desired properties that promise to enable vastly new concepts of energy storage and conversion, photocatalysis, and molecular electronics.

Fate dynamics of environmentally exposed explosive traces.

PubMed

Kunz, Roderick R; Gregory, Kerin E; Aernecke, Matthew J; Clark, Michelle L; Ostrinskaya, Alla; Fountain, Augustus W

2012-04-12

The chemical and physical fates of trace amounts (<50 μg) of explosives containing 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) were determined for the purpose of informing the capabilities of tactical trace explosive detection systems. From these measurements, it was found that the mass decreases and the chemical composition changes on a time scale of hours, with the loss mechanism due to a combination of sublimation and photodegradation. The rates for these processes were dependent on the explosive composition, as well as on both the ambient temperature and the size distribution of the explosive particulates. From these results, a persistence model was developed and applied to model the time dependence of both the mass and areal coverage of the fingerprints, resulting in a predictive capability for determining fingerprint fate. Chemical analysis confirmed that sublimation rates for TNT were depressed by UV (330-400 nm) exposure due to photochemically driven increases in the molecular weight, whereas the opposite was observed for RDX. No changes were observed for PETN upon exposure to UV radiation, and this was attributed to its low UV absorbance.

Frictional properties of single crystals HMX, RDX and PETN explosives.

PubMed

Wu, Y Q; Huang, F L

2010-11-15

The frictional properties of single crystals of cyclotetramethylene tetranitramine (HMX), cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN) secondary explosives are examined using a sensitive friction machine. The explosive crystals used for the measurements are at least 3.5 mm wide. The friction coefficients between crystals of the same explosive (i.e., HMX on HMX, etc.), crystals of different explosives (i.e., HMX on RDX, etc.), and each explosive and a well-polished gauge steel surface are determined. The frictional surfaces are also studied under an environmental scanning electron microscope (ESEM) to analyze surface microstructural changes under increasing loading forces. The friction coefficients vary considerably with increasing normal loading forces and are particularly sensitive to slider shapes, crystal roughness and the mechanical properties of both the slider and the sample. With increasing loading forces, most friction experiments show surface damage, consisting of grooves, debris, and nano-particles, on both the slider and sample. In some cases, a strong evidence of a localized molten state is found in the central region of the friction track. Possible mechanisms that affect the friction coefficient are discussed based on microscopic observations. Copyright © 2010 Elsevier B.V. All rights reserved.

Modelling shock to detonation transition in PETN using HERMES and CREST

NASA Astrophysics Data System (ADS)

Maheswaran, Mary-Ann; Curtis, John; Reaugh, Jack

2013-06-01

The High Explosive Response to MEchanical Stimulus (HERMES) model has been developed to address High Explosive Violent Response (HEVR). It is a material model for use in the both the LS-DYNA finite element and ALE3D hydrocodes that enables the modelling of both shock to detonation (SDT) and deflagration to detonation (DDT) transition. As part of its ongoing development and application, model parameters for the explosive PETN were found by using experimental data for PETN at different densities. PETN was selected because of the availability of both SDT and DDT data. To model SDT and DDT, HERMES uses a subset of the CREST reactive burn model with the Mie-Gruneisen equation of state (EOS) for the unreacted explosive and a look-up table for the gas EOS as generated by Cheetah. The unreacted EOS parameters were found first by calculating the principal isentrope of unreacted PETN at TMD from PETN shock Hugoniot data. Then Pop-plot data for PETN was used to fit the CREST parameters at each density. The resulting new PETN HERMES material model provides a platform for further investigations of SDT and DDT in low density PETN powder. JER's activity was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344, and partially funded by the Joint US DoD/DOE Munitions Technology Development Program.

Cluster evolution during the early stages of heating explosives and its relationship to sensitivity: a comparative study of TATB, β-HMX and PETN by molecular reactive force field simulations.

PubMed

Wen, Yushi; Zhang, Chaoyang; Xue, Xianggui; Long, Xinping

2015-05-14

Clustering is experimentally and theoretically verified during the complicated processes involved in heating high explosives, and has been thought to influence their detonation properties. However, a detailed description of the clustering that occurs has not been fully elucidated. We used molecular dynamic simulations with an improved reactive force field, ReaxFF_lg, to carry out a comparative study of cluster evolution during the early stages of heating for three representative explosives: 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), β-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and pentaerythritol tetranitrate (PETN). These representatives vary greatly in their oxygen balance (OB), molecular structure, stability and experimental sensitivity. We found that when heated, TATB, HMX and PETN differ in the size, amount, proportion and lifetime of their clusters. We also found that the clustering tendency of explosives decreases as their OB becomes less negative. We propose that the relationship between OB and clustering can be attributed to the role of clustering in detonation. That is, clusters can form more readily in a high explosive with a more negative OB, which retard its energy release, secondary decomposition, further decomposition to final small molecule products and widen its detonation reaction zone. Moreover, we found that the carbon content of the clusters increases during clustering, in accordance with the observed soot, which is mainly composed of carbon as the final product of detonation or deflagration.

Elasticity of crystalline molecular explosives

DOE PAGES

Hooks, Daniel E.; Ramos, Kyle J.; Bolme, C. A.; ...

2015-04-14

Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree of consistency and predictability is desired under a range of conditions to a variety of stimuli. Prediction of behaviors from mechanical response and failure to detonation initiation and detonation performance of the material is linked to accurate knowledge of the material structure and first stage of deformation: elasticity. The elastic response of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX), including aspects of material and measurement variability, and computational methods are described in detail. Experimental determinations of elastic tensors are compared, andmore » an evaluation of sources of error is presented. Furthermore, computed elastic constants are also compared for these materials and for triaminotrinitrobenzene (TATB), for which there are no measurements.« less

Analysis of explosives using corona discharge ionization combined with ion mobility spectrometry-mass spectrometry.

PubMed

Lee, Jihyeon; Park, Sehwan; Cho, Soo Gyeong; Goh, Eun Mee; Lee, Sungman; Koh, Sung-Suk; Kim, Jeongkwon

2014-03-01

Corona discharge ionization combined with ion mobility spectrometry-mass spectrometry (IMS-MS) was utilized to investigate five common explosives: cyclonite (RDX), trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclotetramethylenetetranitramine (HMX), and 2,4-dinitrotoluene (DNT). The MS scan and the selected ion IMS analyses confirmed the identities of the existing ion species and their drift times. The ions observed were RDX·NO3(-), TNT(-), PETN·NO3(-), HMX·NO3(-), and DNT(-), with average drift times of 6.93 ms, 10.20 ms, 9.15 ms, 12.24 ms, 11.30 ms, and 8.89 ms, respectively. The reduced ion mobility values, determined from a standard curve calculated by linear regression of (normalized drift times)(-1) versus literature K0 values, were 2.09, 1.38, 1.55, 1.15, 1.25, and 1.60 cm(2) V(-1) s(-1), respectively. The detection limits were found to be 0.1 ng for RDX, 10 ng for TNT, 0.5 ng for PETN, 5.0 ng for HMX, and 10 ng for DNT. Simplified chromatograms were observed when nitrogen, as opposed to air, was used as the drift gas, but the detection limits were approximately 10 times worse (i.e., less sensitivity of detection). © 2013 Elsevier B.V. All rights reserved.

Atomic-Scale Theoretical Studies of Fundamental Properties and Processes in CHNO Plastic-Bonded Explosive Constituent Materials under Static and Dynamic Compression

NASA Astrophysics Data System (ADS)

Sewell, Thomas

2013-06-01

The results of recent theoretical atomic-scale studies of CHNO plastic-bonded explosive constituent materials will be presented, emphasizing the effects of static and dynamic compression on structure, vibrational spectroscopy, energy redistribution, and dynamic deformation processes. Among the chemical compounds to be discussed are pentaerythritol tetranitrate (PETN), hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX), nitromethane, and hydroxyl-terminated polybutadiene (HTPB). Specific topics to be discussed include pressure-dependent terahertz IR absorption spectra in crystalline PETN and RDX, microscopic material flow characteristics and energy localization during and after pore collapse in shocked (100)-oriented RDX, establishment of local thermodynamic temperature and the approach to thermal equilibrium in shocked (100)-oriented nitromethane, and structural changes and relaxation phenomena that occur in shocked amorphous cis-HTPB. In the case of shocked HTPB, comparisons will be made between results obtained using fully-atomic and coarse-grained (united atom) molecular dynamics force field models. Rather than attempting to discuss any given topic in extended detail, 3-4 vignettes will be presented that highlight outstanding scientific questions and the predictive methods and tools we are developing to answer them. The U.S. Defense Threat Reduction Agency and Office of Naval Research supported this research.

Shock Initiation of Explosives - High Temperature Hot Spots Explained

NASA Astrophysics Data System (ADS)

Bassett, Will

2017-06-01

The pore-collapse mechanism for hot spot creation is currently one of the most intensely studied subjects in the initiation of energetic materials. In the present study, we use 1.5 - 3.5 km s-1 laser-driven flyer plates to impact microgram charges of both polymer-bound and pure pentaerythritol tetranitrate (PETN) while recording the temperature and spatially-averaged emissivity with a high-speed optical pyrometer. The 32-color pyrometer has nanosecond time resolution and a high dynamic range with sensitivity to temperatures from 7000 to 2000 K. Hot spot temperatures of 4000 K at impact are observed in the polymer-bound explosive charges where an elastomeric binder is used to fill void spaces. In pure PETN and more heterogeneous polymer-bound charges, in which significant void space is present, hot spot temperatures of 6000 K are observed, similar to previous reports with significant porosity. We attribute these high temperatures to gas-phase products formed in-situ being compressed under the driving shock. Experiments performed under various gas environments (air, butane, etc.) showed a strong influence on observed temperature upon impact. Control experiments where the PETN in the polymer-bound charges were replaced with sucrose and silica reinforce the result that hot spots are a result of in-situ gas formation from decomposition of organic molecules. US Air Force Office of Scientific Research awards FA9550-14-1-0142 and FA9550-16-1-0042; US Army Research Office award W911NF-13-1-0217; Defense Threat Reduction Agency award HDTRA1-12-1-0011. In collaboration with: Belinda Pacheco and Dana Dlott, University of Illinois at Urbana Champaign.

Ability of the Confined Explosive Component Water Gap Test STANAG 4363 to Assess the Shock Sensitivity of MM-Scale Detonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lefrancois, A S; Roeske, F; Benterou, J

2006-02-10

The Explosive Component Water Gap Test (ECWGT) has been validated to assess the shock sensitivity of lead and booster components having a diameter larger than 5 mm. Several countries have investigated by experiments and numerical simulations the effect of confinement on the go/no go threshold for Pentaerythritol Tetranitrate (PETN) pellets having a height and diameter of 3 mm, confined by a steel annulus of wall thickness 1-3.5 mm. Confinement of the PETN by a steel annulus of the same height of the pellet with 1-mm wall thickness makes the component more sensitive (larger gap). As the wall thickness is increasedmore » to 2-mm, the gap increases a lesser amount, but when the wall thickness is increased to 3.5-mm a decrease in sensitivity is observed (smaller gap). This decrease of the water gap has been reproduced experimentally. Recent numerical simulations using Ignition and Growth model [1] for the PETN Pellet have reproduced the experimental results for the steel confinement up to 2 mm thick [2]. The presence of a stronger re-shock following the first input shock from the water and focusing on the axis have been identified in the pellet due to the steel confinement. The double shock configuration is well-known to lead in some cases to shock desensitization. This work presents the numerical simulations using Ignition and Growth model for LX16 (PETN based HE) and LX19 (CL20 based HE) Pellets [3] in order to assess the shock sensitivity of mm-scale detonators. The pellets are 0.6 mm in diameter and 3 mm length with different type of steel confinement 2.2 mm thick and 4.7 mm thick. The influence of an aluminum confinement is calculated for the standard LX 16 pellet 3 mm in diameter and 3 mm in height. The question of reducing the size of the donor charge is also investigated to small scale the test itself.« less

Analysis of nitrogen-based explosives with desorption atmospheric pressure photoionization mass spectrometry.

PubMed

Kauppila, T J; Flink, A; Pukkila, J; Ketola, R A

2016-02-28

Fast methods that allow the in situ analysis of explosives from a variety of surfaces are needed in crime scene investigations and home-land security. Here, the feasibility of the ambient mass spectrometry technique desorption atmospheric pressure photoionization (DAPPI) in the analysis of the most common nitrogen-based explosives is studied. DAPPI and desorption electrospray ionization (DESI) were compared in the direct analysis of trinitrotoluene (TNT), trinitrophenol (picric acid), octogen (HMX), cyclonite (RDX), pentaerythritol tetranitrate (PETN), and nitroglycerin (NG). The effect of different additives in DAPPI dopant and in DESI spray solvent on the ionization efficiency was tested, as well as the suitability of DAPPI to detect explosives from a variety of surfaces. The analytes showed ions only in negative ion mode. With negative DAPPI, TNT and picric acid formed deprotonated molecules with all dopant systems, while RDX, HMX, PETN and NG were ionized by adduct formation. The formation of adducts was enhanced by addition of chloroform, formic acid, acetic acid or nitric acid to the DAPPI dopant. DAPPI was more sensitive than DESI for TNT, while DESI was more sensitive for HMX and picric acid. DAPPI could become an important method for the direct analysis of nitroaromatics from a variety of surfaces. For compounds that are thermally labile, or that have very low vapor pressure, however, DESI is better suited. Copyright © 2016 John Wiley & Sons, Ltd.

Low-pressure barrier discharge ion source using air as a carrier gas and its application to the analysis of drugs and explosives.

PubMed

Usmanov, Dilshadbek T; Yu, Zhan; Chen, Lee Chuin; Hiraoka, Kenzo; Yamabe, Shinichi

2016-02-01

In this work, a low-pressure air dielectric-barrier discharge (DBD) ion source using a capillary with the inner diameter of 0.115 and 12 mm long applicable to miniaturized mass spectrometers was developed. The analytes, trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5,7-tetranitroperhydro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), nitroglycerine (NG), hexamethylene triperoxide diamine (HMTD), caffeine, cocaine and morphine, introduced through the capillary, were ionized by a low-pressure air DBD. The ion source pressures were changed by using various sizes of the ion sampling orifice. The signal intensities of those analytes showed marked pressure dependence. TNT was detected with higher sensitivity at lower pressure but vice versa for other analytes. For all analytes, a marked signal enhancement was observed when a grounded cylindrical mesh electrode was installed in the DBD ion source. Among nine analytes, RDX, HMX, NG and PETN could be detected as cluster ions [analyte + NO3 ](-) even at low pressure and high temperature up to 180 °C. The detection indicates that these cluster ions are stable enough to survive under present experimental conditions. The unexpectedly high stabilities of these cluster ions were verified by density functional theory calculation. Copyright © 2016 John Wiley & Sons, Ltd.

High-pressure/high-temperature polymorphs of energetic materials by first-principles simulations

NASA Astrophysics Data System (ADS)

Le, Nam; Schweigert, Igor

2017-06-01

Energetic molecular crystals exhibit complex phase diagrams that include solid-solid phase transitions, melting, and decomposition. Sorescu and Rice have recently demonstrated that first-principles molecular dynamics (MD) simulations based on dispersion-corrected density functional theory (DFT) can capture the α to γ phase transition in hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) on time scales of several picoseconds. Motivated by their work, we are using DFT-based MD to model the relative stability of solid phases in several molecular crystals. In this presentation, we report simulations of pentaerythritol tetranitrate (PETN) and 2,4,6-trinitrotoluene (TNT) under high pressures and temperatures and compare them with experimentally observed polymorphs. This work was supported by the U.S. Naval Research Laboratory via the National Research Council and by the Office of Naval Research through the U.S. Naval Research Laboratory.

Unreacted equation of states of typical energetic materials under static compression: A review

NASA Astrophysics Data System (ADS)

Zhaoyang, Zheng; Jijun, Zhao

2016-07-01

The unreacted equation of state (EOS) of energetic materials is an important thermodynamic relationship to characterize their high pressure behaviors and has practical importance. The previous experimental and theoretical works on the equation of state of several energetic materials including nitromethane, 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), hexanitrostilbene (HNS), hexanitrohexaazaisowurtzitane (HNIW or CL-20), pentaerythritol tetranitrate (PETN), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), triamino-trinitrobenzene (TATB), 1,1-diamino-2,2-dinitroethene (DADNE or FOX-7), and trinitrotoluene (TNT) are reviewed in this paper. The EOS determined from hydrostatic and non-hydrostatic compressions are discussed and compared. The theoretical results based on ab initio calculations are summarized and compared with the experimental data. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174045 and 11404050).

Molecular recognition using receptor-free nanomechanical infrared spectroscopy based on a quantum cascade laser

PubMed Central

Kim, Seonghwan; Lee, Dongkyu; Liu, Xunchen; Van Neste, Charles; Jeon, Sangmin; Thundat, Thomas

2013-01-01

Speciation of complex mixtures of trace explosives presents a formidable challenge for sensors that rely on chemoselective interfaces due to the unspecific nature of weak intermolecular interactions. Nanomechanical infrared (IR) spectroscopy provides higher selectivity in molecular detection without using chemoselective interfaces by measuring the photothermal effect of adsorbed molecules on a thermally sensitive microcantilever. In addition, unlike conventional IR spectroscopy, the detection sensitivity is drastically enhanced by increasing the IR laser power, since the photothermal signal comes from the absorption of IR photons and nonradiative decay processes. By using a broadly tunable quantum cascade laser for the resonant excitation of molecules, we increased the detection sensitivity by one order of magnitude compared to the use of a conventional IR monochromator. Here, we demonstrate the successful speciation and quantification of picogram levels of ternary mixtures of similar explosives (trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX), and pentaerythritol tetranitrate (PETN)) using nanomechanical IR spectroscopy. PMID:23346368

Impaired vasodilator response to organic nitrates in isolated basilar arteries

PubMed Central

Martens, Dorothee; Kojda, Georg

2001-01-01

The differential responsiveness of various sections and regions in the vascular system to the vasodilator activity of organic nitrates is important for the beneficial antiischaemic effects of these drugs. In this study we examined the vasodilator activity of organic nitrates in cerebral arteries, where vasodilation causes substantial nitrate induced headache. Isolated porcine basilar and coronary arteries were subjected to increasing concentrations of glyceryl trinitrate (GTN), isosorbide-5-nitrate (ISMN) and pentaerythritol tetranitrate (PETN). S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and endothelium-dependent vasodilation was investigated for comparison purpose. The vasodilator potency (halfmaximal effective concentration in −logM) of GTN (4.33±0.1, n=8), ISMN (1.61±0.07, n=7) and PETN (>10 μM, n=7) in basilar arteries was more than 100 fold lower than that of GTN (6.52±0.06, n=12), ISMN (3.66±0.08, n=10) and PETN (6.3±0.13, n=8) observed in coronary arteries. In striking contrast, the vasodilator potency of SNAP (halfmaximal effective concentration in −logM) was almost similar in basilar (7.76±0.05, n=7) and coronary arteries (7.59±0.05, n=9). Likewise, no difference in endothelium dependent relaxation was observed. Denudation of the endothelium resulted in a small increase of the vasodilator potency (halfmaximal effective concentration in −logM) of GTN (4.84±0.09, n=7, P<0.03) in basilar arteries and similar results were obtained in the presence of the NO-synthase inhibitor Nω-nitro-L-arginine (4.59±0.05, n=9, P<0.03). These results suggest that cerebral conductance blood vessels such as porcine basilar arteries seems to have a reduced expression and/or activity of certain cellular enzymatic electron transport systems such as cytochrome P450 enzymes, which are necessary to bioconvert organic nitrates to NO. PMID:11156558

ONE-DIMENSIONAL TIME TO EXPLOSION (THERMAL SENSITIVITY) TESTS ON PETN, PBX-9407, LX-10, AND LX-17

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Peter C.; Strout, Steve; McClelland, Matthew

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to thermal explosion, threshold thermal explosion temperature, and determine the kinetic parameters of thermal decomposition of energeticmore » materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the results of our recent ODTX experiments on PETN powder, PBX-9407 pressed part, LX-10 pressed part, LX-17 pressed part and compares the test data that were obtained decades ago with the older version of ODTX system. Test results show the thermal sensitivity of various materials tested in the following order: PETN> PBX-9407 > LX-10 > LX-17.« less

Installation Restoration of Frankford Arsenal, Pennsylvania, Concept Plan

DTIC Science & Technology

1977-09-01

combined with 650 ml of tetrazine slurry. To this mix was added other components (e.g., antimony sulfide , powdered aluminum, PETN, barium nitrate and a...such materials as barium nitrate, magnesium and aluminum powders, potassium perchlorate, iron oxide, red phosphorus, strontium peroxide, strontium...soluble in acetone and nethyl acetate. Chemical Activity: Decomposed slowly by boiling 2.5% aqueous caustic;0 decomposed slowly by sodium sulfide

Experimental and Modeling Characterization of PETN Mobilization Mechanisms During Recrystallization at Ambient Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnham, A K; Gee, R; Maiti, A

2005-11-03

Experimental measurements suggest that pentaerythritoltetranitrate (PETN) undergoes changes at the molecular level that cause macroscopic changes in the overall PETN powder characteristics over time. These changes have been attributed to the high molecular mobility of PETN, but the underlying mechanism(s) responsible for this redistribution are still uncertain. Two basic approaches have been implemented in the past year to provide insight into the nature of these underlying mechanisms. The first approach is of an experimental nature, utilizing both AFM and evaporation measurements, which address both surface mobility and evaporation. These data include AFM measurements performed at LLNL and evaporation rate measurementsmore » performed at Texas Tech. These results are compared to earlier vapor pressure measurements performed at SNL, and estimates of recrystallization time frames are given. The second approach utilizes first-principle calculations and simulations that will be used to compare directly to those experimental quantities measured. We are developing an accurate intermolecular potential for PETN, which via kinetic Monte Carlo (KMC) simulations would mimic real crystallite shapes. Once the basic theory is in place for the growth of single crystallites, we will be in a position to investigate realistic grain coarsening phenomena in multi-crystallite simulations. This will also enable us to study how to control the morphological evolution, e.g., through thermal cycling, or through the action of custom additives and impurities.« less

New insights into bioactivation of organic nitrates, nitrate tolerance and cross-tolerance.

PubMed

Daiber, A; Wenzel, P; Oelze, M; Münzel, T

2008-01-01

Organic nitrates still represent a group of very effective anti-ischemic drugs used for the treatment of patients with stable angina, acute myocardial infarction and chronic congestive heart failure. Long-term therapy with organic nitrates, however, results in a rapid development of nitrate tolerance blunting their hemodynamic and antiischemic efficacy. Recent studies revealed that mitochondrial reactive oxygen species (ROS) formation and a subsequent oxidative inactivation of nitrate reductase, the mitochondrial aldehyde dehydrogenase (ALDH-2), play an important role for the development of nitrate and crosstolerance. The present review focuses firstly on the role of ALDH-2 for organic nitrate bioactivation and secondly on the role of oxidative stress in the development of tolerance and cross-tolerance (endothelial dysfunction) in response to various organic nitrates. Finally, we would like to draw the reader's attention to the protective properties of the organic nitrate pentaerithrityl tetranitrate (PETN), which, in contrast to all other organic nitrates, is able to upregulate enzymes with a strong antioxidative capacity thereby preventing tolerance and the development of endothelial dysfunction.

Synthesis of a new energetic nitrate ester

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavez, David E

2008-01-01

Nitrate esters have been known as useful energetic materials since the discovery of nitroglycerin by Ascanio Sobrero in 1846. The development of methods to increase the safety and utility of nitroglycerin by Alfred Nobel led to the revolutionary improvement in the utility of nitroglycerin in explosive applications in the form of dynamite. Since then, many nitrate esters have been prepared and incorporated into military applications such as double-based propellants, detonators and as energetic plasticizers. Nitrate esters have also been shown to have vasodilatory effects in humans and thus have been studied and used for treatments of ailments such as angina.more » The mechanism of the biological response towards nitrate esters has been elucidated recently. Interestingly, many of the nitrate esters used for military purposes are liquids (ethylene glycol dinitrate, propylene glycol dinitrate, etc). Pentaerythritol tetranitrate (PETN) is one of the only solid nitrate esters, besides nitrocellulose, that is used in any application. Unfortunately, PETN melting point is above 100 {sup o}C, and thus must be pressed as a solid for detonator applications. A more practical material would be a melt-castable explosive, for potential simplification of manufacturing processes. Herein we describe the synthesis of a new energetic nitrate ester (1) that is a solid at ambient temperatures, has a melting point of 85-86 {sup o}C and has the highest density of any known nitrate ester composed only of carbon, hydrogen, nitrogen and oxygen. We also describe the chemical, thermal and sensitivity properties of 1 as well as some preliminary explosive performance data.« less

Experimental and TD-DFT study of optical absorption of six explosive molecules: RDX, HMX, PETN, TNT, TATP, and HMTD.

PubMed

Cooper, Jason K; Grant, Christian D; Zhang, Jin Z

2013-07-25

Time dependent density function theory (TD-DFT) has been utilized to calculate the excitation energies and oscillator strengths of six common explosives: RDX (1,3,5-trinitroperhydro-1,3,5-triazine), β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), TATP (triacetone triperoxide), HMTD (hexamethylene triperoxide diamine), TNT (2,4,6-trinitrotoluene), and PETN (pentaerythritol tetranitrate). The results were compared to experimental UV-vis absorption spectra collected in acetonitrile. Four computational methods were tested including: B3LYP, CAM-B3LYP, ωB97XD, and PBE0. PBE0 outperforms the other methods tested. Basis set effects on the electronic energies and oscillator strengths were evaluated with 6-31G(d), 6-31+G(d), 6-31+G(d,p), and 6-311+G(d,p). The minimal basis set required was 6-31+G(d); however, additional calculations were performed with 6-311+G(d,p). For each molecule studied, the natural transition orbitals (NTOs) were reported for the most prominent singlet excitations. The TD-DFT results have been combined with the IPv calculated by CBS-QB3 to construct energy level diagrams for the six compounds. The results suggest optimization approaches for fluorescence based detection methods for these explosives by guiding materials selections for optimal band alignment between fluorescent probe and explosive analyte. Also, the role of the TNT Meisenheimer complex formation and the resulting electronic structure thereof on of the quenching mechanism of II-VI semiconductors is discussed.

Large-Scale Reactive Atomistic Simulation of Shock-induced Initiation Processes in Energetic Materials

NASA Astrophysics Data System (ADS)

Thompson, Aidan

2013-06-01

Initiation in energetic materials is fundamentally dependent on the interaction between a host of complex chemical and mechanical processes, occurring on scales ranging from intramolecular vibrations through molecular crystal plasticity up to hydrodynamic phenomena at the mesoscale. A variety of methods (e.g. quantum electronic structure methods (QM), non-reactive classical molecular dynamics (MD), mesoscopic continuum mechanics) exist to study processes occurring on each of these scales in isolation, but cannot describe how these processes interact with each other. In contrast, the ReaxFF reactive force field, implemented in the LAMMPS parallel MD code, allows us to routinely perform multimillion-atom reactive MD simulations of shock-induced initiation in a variety of energetic materials. This is done either by explicitly driving a shock-wave through the structure (NEMD) or by imposing thermodynamic constraints on the collective dynamics of the simulation cell e.g. using the Multiscale Shock Technique (MSST). These MD simulations allow us to directly observe how energy is transferred from the shockwave into other processes, including intramolecular vibrational modes, plastic deformation of the crystal, and hydrodynamic jetting at interfaces. These processes in turn cause thermal excitation of chemical bonds leading to initial chemical reactions, and ultimately to exothermic formation of product species. Results will be presented on the application of this approach to several important energetic materials, including pentaerythritol tetranitrate (PETN) and ammonium nitrate/fuel oil (ANFO). In both cases, we validate the ReaxFF parameterizations against QM and experimental data. For PETN, we observe initiation occurring via different chemical pathways, depending on the shock direction. For PETN containing spherical voids, we observe enhanced sensitivity due to jetting, void collapse, and hotspot formation, with sensitivity increasing with void size. For ANFO, we examine the effect of reaction rates on shock direction, fuel oil fraction, and crystal/fuel oil/void microstructural arrangement. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Dept. of Energy's National Nuclear Security Admin. under contract DEAC0494AL85000.

Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress.

PubMed

Daiber, Andreas; Münzel, Thomas

2015-10-10

Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3',-5'-monophosphate (cGMP) levels lead to an activation of the cGMP-dependent kinase I, thereby causing the relaxation of the vascular smooth muscle by decreasing intracellular calcium concentrations. The hemodynamic and anti-ischemic effects of organic nitrates are rapidly lost upon long-term (low-dose) administration due to the rapid development of tolerance and endothelial dysfunction, which is in most cases linked to increased intracellular oxidative stress. Enzymatic sources of reactive oxygen species under nitrate therapy include mitochondria, NADPH oxidases, and an uncoupled •NO synthase. Acute high-dose challenges with organic nitrates cause a similar loss of potency (tachyphylaxis), but with distinct pathomechanism. The differences among organic nitrates are highlighted regarding their potency to induce oxidative stress and subsequent tolerance and endothelial dysfunction. We also address pleiotropic effects of organic nitrates, for example, their capacity to stimulate antioxidant pathways like those demonstrated for PETN, all of which may prevent adverse effects in response to long-term therapy. Based on these considerations, we will discuss and present some preclinical data on how the nitrate of the future should be designed.

Rapid identification and desorption mechanisms of nitrogen-based explosives by ambient micro-fabricated glow discharge plasma desorption/ionization (MFGDP) mass spectrometry.

PubMed

Tian, CaiYan; Yin, JinWei; Zhao, ZhongJun; Zhang, Yinchenxi; Duan, YiXiang

2017-05-15

A novel technique of micro-fabricated glow discharge plasma desorption/ionization mass spectrometry was investigated for the first time in negative ion mode in this study. Negative ion micro-fabricated glow discharge plasma desorption/ionization mass spectrometry (NI-MFGDP-MS) was successfully applied to identify trace explosives in open air. Six explosives and explosives-related compounds were directly analyzed in seconds with this ion source. The ions of [M-H] - were predominant for 2-methyl-1,3,5-trinitrobenzene (trinitrotoluene, TNT) and 2,4,6-trinitrophenol (picric acid), and [M+NO 3 ] - were dominant ions for 1,3,5-trinitro-perhydro-1,3,5-triazine (cyclonite, RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (octogen, HMX), 1,2,3-trinitroxypropane (nitroglycerin, NG), and pentaerythritol tetranitrate (PETN). The limits of detection (LOD) were from 87.5pgmm -2 to 0.4 fg mm -2 and the relative standard deviation (RSD) ranged between 5.8% and 16.8% for the explosives involved in this study. The reliability of NI-MFGDP-MS was characterized by the analysis of a picric acid-RDX-PETN mixture and a mixture of RDX-pond water. NI-MFGDP-MS and ESI-MS were compared with these explosives and along with collision induced dissociation (CID) experiments. The results showed that electron capture, proton abstraction reaction, nucleophilic attack, ion-molecule attachment, decomposition and anion attachment took place during the NI-MFGDP-MS measurement. These findings provide a guideline and a supplement to the chemical libraries for rapid and accurate detection of explosives. The method shows great potential for fast, in situ, on-line and high throughput detection of explosives in the field of antiterrorism. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of paper spray ionization for explosives analysis.

PubMed

Tsai, Chia-Wei; Tipple, Christopher A; Yost, Richard A

2017-10-15

A desired feature in the analysis of explosives is to decrease the time of the entire analysis procedure, including sampling. A recently utilized ambient ionization technique, paper spray ionization (PSI), provides the possibility of combining sampling and ionization. However, an interesting phenomenon that occurs in generating negatively charged ions pose some challenges in applying PSI to explosives analysis. The goal of this work is to investigate the possible solutions for generating explosives ions in negative mode PSI. The analysis of 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) was performed. Several solvent systems with different surface tensions and additives were compared to determine their effect on the ionization of explosives. The solvents tested include tert-butanol, isopropanol, methanol, and acetonitrile. The additives tested were carbon tetrachloride and ammonium nitrate. Of the solvents tested, isopropanol yielded the best results. In addition, adding ammonium nitrate to the isopropanol enhanced the analyte signal. Experimentally determined limits of detection (LODs) as low as 0.06 ng for PETN, on paper, were observed with isopropanol and the addition of 0.4 mM ammonium nitrate as the spray solution. In addition, the explosive components of two plastic explosive samples, Composition 4 and Semtex, were successfully analyzed via surface sampling when using the developed method. The analysis of explosives using PSI-MS in negative ion mode was achieved. The addition of ammonium nitrate to isopropanol, in general, enhanced the analyte signal and yielded better ionization stability. Real-world explosive samples were analyzed, which demonstrates one of the potential applications of PSI-MS analysis. Copyright © 2017 John Wiley & Sons, Ltd.

Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress

PubMed Central

2015-01-01

Abstract Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3′,-5′-monophosphate (cGMP) levels lead to an activation of the cGMP-dependent kinase I, thereby causing the relaxation of the vascular smooth muscle by decreasing intracellular calcium concentrations. The hemodynamic and anti-ischemic effects of organic nitrates are rapidly lost upon long-term (low-dose) administration due to the rapid development of tolerance and endothelial dysfunction, which is in most cases linked to increased intracellular oxidative stress. Enzymatic sources of reactive oxygen species under nitrate therapy include mitochondria, NADPH oxidases, and an uncoupled •NO synthase. Acute high-dose challenges with organic nitrates cause a similar loss of potency (tachyphylaxis), but with distinct pathomechanism. The differences among organic nitrates are highlighted regarding their potency to induce oxidative stress and subsequent tolerance and endothelial dysfunction. We also address pleiotropic effects of organic nitrates, for example, their capacity to stimulate antioxidant pathways like those demonstrated for PETN, all of which may prevent adverse effects in response to long-term therapy. Based on these considerations, we will discuss and present some preclinical data on how the nitrate of the future should be designed. Antioxid. Redox Signal. 23, 899–942. PMID:26261901

Integrated Data Collection Analysis (IDCA) Program - AN and Bullseye Smokeless Powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of ammonium nitrate (AN) mixed with Bullseye® smokeless powder (Gunpowder). The participants found the AN/Gunpowder to: 1) have a range of sensitivity to impact, comparable to or less than RDX, 2) be fairly insensitive to friction as measured by BAM and ABL, 3) have a range for ESD, from insensitive to more sensitive than PETN, and 4) have thermal sensitivity aboutmore » the same as PETN and Gunpowder. This effort, funded by the Department of Homeland Security (DHS), is putting the issues of safe handling of these materials in perspective with standard military explosives. The study is adding SSST testing results for a broad suite of different HMEs to the literature. Ultimately the study has the potential to suggest new guidelines and methods and possibly establish the SSST testing accuracies needed when developing safe handling practices for HMEs. Each participating testing laboratory uses identical test materials and preparation methods. Note, however, the test procedures differ among the laboratories. The testing performers involved are Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Indian Head Division, Naval Surface Warfare Center, (NSWC IHD), Sandia National Laboratories (SNL), and Air Force Research Laboratory (AFRL/RXQL). These tests are conducted as a proficiency study in order to establish some consistency in test protocols, procedures, and experiments and to compare results when these testing variables cannot be made consistent. Keywords: Small-scale safety testing, proficiency test, impact-, friction-, spark discharge-, thermal testing, round-robin test, safety testing protocols, HME, RDX, potassium perchlorate, potassium chlorate, sodium chlorate, sugar, dodecane, PETN, carbon, ammonium nitrate, Gunpowder, Bullseye® smokeless powder.« less

Electronic tongue for nitro and peroxide explosive sensing.

PubMed

González-Calabuig, Andreu; Cetó, Xavier; Del Valle, Manel

2016-06-01

This work reports the application of a voltammetric electronic tongue (ET) towards the simultaneous determination of both nitro-containing and peroxide-based explosive compounds, two families that represent the vast majority of compounds employed either in commercial mixtures or in improvised explosive devices. The multielectrode array was formed by graphite, gold and platinum electrodes, which exhibited marked mix-responses towards the compounds examined; namely, 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), N-methyl-N,2,4,6-tetranitroaniline (Tetryl) and triacetone triperoxide (TATP). Departure information was the set of voltammograms, which were first analyzed by means of principal component analysis (PCA) allowing the discrimination of the different individual compounds, while artificial neural networks (ANNs) were used for the resolution and individual quantification of some of their mixtures (total normalized root mean square error for the external test set of 0.108 and correlation of the obtained vs. expected concentrations comparison graphs r>0.929). Copyright © 2016 Elsevier B.V. All rights reserved.

Detonation corner turning in vapor-deposited explosives using the micromushroom test

NASA Astrophysics Data System (ADS)

Tappan, Alexander S.; Yarrington, Cole D.; Knepper, Robert

2017-06-01

Detonation corner turning describes the ability of a detonation wave to propagate into unreacted explosive that is not immediately in the path normal to the wave. The classic example of corner turning is cylindrical and involves a small diameter explosive propagating into a larger diameter explosive as described by Los Alamos' Mushroom test (e.g. (Hill, Seitz et al. 1998)), where corner turning is inferred from optical breakout of the detonation wave. We present a complimentary method to study corner turning in millimeter-scale explosives through the use of vapor deposition to prepare the slab (quasi-2D) analog of the axisymmetric mushroom test. Because the samples are in a slab configuration, optical access to the explosive is excellent and direct imaging of the detonation wave and ``dead zone'' that results during corner turning is possible. Results are compared for explosives that demonstrate a range of behaviors, from pentaerythritol tetranitrate (PETN), which has corner turning properties that are nearly ideal; to HNAB (hexanitroazobenzene), which has corner turning properties that reveal a substantial dead zone. Results are discussed in the context of microstructure and detonation failure thickness.

Sandia National Laboratories Small-Scale Sensitivity Testing (SSST) Report: Calcium Nitrate Mixtures with Various Fuels.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Jason Joe

Based upon the presented sensitivity data for the examined calcium nitrate mixtures using sugar and sawdust, contact handling/mixing of these materials does not present hazards greater than those occurring during handling of dry PETN powder. The aluminized calcium nitrate mixtures present a known ESD fire hazard due to the fine aluminum powder fuel. These mixtures may yet present an ESD explosion hazard, though this has not been investigated at this time. The detonability of these mixtures will be investigated during Phase III testing.

Analytical Method for Determining Tetrazene in Water.

DTIC Science & Technology

1987-12-01

8217-decanesulfonic acid sodium salt. The mobile phase pH was adjusted to 3 with glacial acetic acid. The modified mobile phase was optimal for separating of...modified with sodium tartrate, gave a well-defined reduction wave at the dropping mercury electrode. The height of the reduction wave was proportional to...anitmony trisulphide, nitrocellulose, PETN, powdered aluminum and calcium silicide . The primer samples were sequentially extracted, first with

Shock Desensitization Effect in the STANAG 4363 Confined Explosive Component Water Gap Test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lefrancois, A S; Lee, R S; Tarver, C M

2006-06-07

The Explosive Component Water Gap Test (ECWGT) in the Stanag 4363 has been recently investigated to assess the shock sensitivity of lead and booster components having a diameter less than 5 mm. For that purpose, Pentaerythritol Tetranitrate (PETN) based pellets having a height and diameter of 3 mm have been confined by a steel annulus of wall thickness 1-3.5 mm and with the same height as the pellet. 1-mm wall thickness makes the component more sensitive (larger gap). As the wall thickness is increased to 2-mm, the gap increases a lesser amount, but when the wall thickness is increased tomore » 3.5-mm a decrease in sensitivity is observed (smaller gap). This decrease of the water gap has been reproduced experimentally by many nations. Numerical simulations using Ignition and Growth model have been performed in this paper and have reproduced the experimental results for the steel confinement up to 2 mm thick and aluminum confinement. A stronger re-shock following the first input shock from the water is focusing on the axis due to the confinement. The double shock configuration is well-known to lead in some cases to shock desensitization.« less

Organic nitrates: update on mechanisms underlying vasodilation, tolerance and endothelial dysfunction.

PubMed

Münzel, Thomas; Steven, Sebastian; Daiber, Andreas

2014-12-01

Given acutely, organic nitrates, such as nitroglycerin (GTN), isosorbide mono- and dinitrates (ISMN, ISDN), and pentaerythrityl tetranitrate (PETN), have potent vasodilator and anti-ischemic effects in patients with acute coronary syndromes, acute and chronic congestive heart failure and arterial hypertension. During long-term treatment, however, side effects such as nitrate tolerance and endothelial dysfunction occur, and therapeutic efficacy of these drugs rapidly vanishes. Recent experimental and clinical studies have revealed that organic nitrates per se are not just nitric oxide (NO) donors, but rather a quite heterogeneous group of drugs considerably differing for mechanisms underlying vasodilation and the development of endothelial dysfunction and tolerance. Based on this, we propose that the term nitrate tolerance should be avoided and more specifically the terms of GTN, ISMN and ISDN tolerance should be used. The present review summarizes preclinical and clinical data concerning organic nitrates. Here we also emphasize the consequences of chronic nitrate therapy on the supersensitivity of the vasculature to vasoconstriction and on the increased autocrine expression of endothelin. We believe that these so far rather neglected and underestimated side effects of chronic therapy with at least GTN and ISMN are clinically important. Copyright © 2014 Elsevier Inc. All rights reserved.

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

NASA Astrophysics Data System (ADS)

Shan, Tzu-Ray; Wixom, Ryan R.; Thompson, Aidan P.

2016-08-01

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. The formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

A review of Explosives Used in Explosive Excavation Research Laboratory Projects Since 1969

DTIC Science & Technology

1974-12-01

Boron compounds Potassium dichramat« Antimony compounds Bismuth compounds P«riodat«s Litharge Guar gum (polysaccSarid«) Storch Acrylomid... gum , and gelled with a cross- linking agent. The i-arliest slurries used Government surplus TNT as a fuel-sensitizer, but the majority o...Nonexplosive TNT PETN RDX Rentalite Composition B Guanidine nitrate Smokeless powder Nitres*: ch Alky’amine nitrates Nit.omannite Aluminum Sugar

Simple multispectral imaging approach for determining the transfer of explosive residues in consecutive fingerprints.

PubMed

Lees, Heidi; Zapata, Félix; Vaher, Merike; García-Ruiz, Carmen

2018-07-01

This novel investigation focused on studying the transfer of explosive residues (TNT, HMTD, PETN, ANFO, dynamite, black powder, NH 4 NO 3 , KNO 3 , NaClO 3 ) in ten consecutive fingerprints to two different surfaces - cotton fabric and polycarbonate plastic - by using multispectral imaging (MSI). Imaging was performed employing a reflex camera in a purpose-built photo studio. Images were processed in MATLAB to select the most discriminating frame - the one that provided the sharpest contrast between the explosive and the material in the red-green-blue (RGB) visible region. The amount of explosive residues transferred in each fingerprint was determined as the number of pixels containing explosive particles. First, the pattern of PETN transfer by ten different persons in successive fingerprints was studied. No significant differences in the pattern of transfer of PETN between subjects were observed, which was also confirmed by multivariate analysis of variance (MANOVA). Then, the transfer of traces of the nine above explosives in ten consecutive fingerprints to cotton fabric and polycarbonate plastic was investigated. The obtained results demonstrated that the amount of explosive residues deposited on successive fingerprints tended to undergo a power or exponential decrease, with the exception of inorganic salts (NH 4 NO 3 , KNO 3 , NaClO 3 ) and ANFO (consists of 90% NH 4 NO 3 ). Copyright © 2018 Elsevier B.V. All rights reserved.

Functional Characterization of Lpt3 and Lpt6, the Inner-Core Lipooligosaccharide Phosphoethanolamine Transferases from Neisseria meningitidis▿

PubMed Central

Wenzel, Cory Q.; St. Michael, Frank; Stupak, Jacek; Li, Jianjun; Cox, Andrew D.; Richards, James C.

2010-01-01

The lipooligosaccharide (LOS) of Neisseria meningitidis contains heptose (Hep) residues that are modified with phosphoethanolamine (PEtn) at the 3 (3-PEtn) and/or 6 (6-PEtn) position. The lpt3 (NMB2010) and lpt6 (NMA0408) genes of N. meningitidis, which are proposed to encode the required HepII 3- and 6-PEtn transferases, respectively, were cloned and overexpressed as C-terminally polyhistidine-tagged fusion proteins in Escherichia coli and found to localize to the inner membrane, based on sucrose density gradient centrifugation. Lpt3-His6 and Lpt6-His6 were purified from Triton X-100-solubilized membranes by nickel chelation chromatography, and dot blot analysis of enzymatic reactions with 3-PEtn- and 6-PEtn-specific monoclonal antibodies demonstrated conclusively that Lpt3 and Lpt6 are phosphatidylethanolamine-dependent LOS HepII 3- and 6-PEtn transferases, respectively, and that both enzymes are capable of transferring PEtn to both fully acylated LOS and de-O-acylated (de-O-Ac) LOS. Further enzymatic studies using capillary electrophoresis-mass spectrometry (MS) demonstrated that both Lpt3 and Lpt6 are capable of transferring PEtn to de-O-Ac LOS molecules already containing PEtn at the 6 and 3 positions of HepII, respectively, demonstrating that there is no obligate order of PEtn addition in the generation of 3,6-di-PEtn LOS moieties in vitro. PMID:19854897

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

DOE PAGES

Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

2016-08-01

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

Manipulating explosive sensitivity through structural modifications in a nitrate ester system

NASA Astrophysics Data System (ADS)

Manner, Virginia

2017-06-01

Understanding how condensed phase effects influence sensitivity is essential for developing next generation insensitive high explosives. However, the ability to predictably manipulate explosive sensitivity remains an elusive goal. Explosive sensitivity has been suggested to be governed by multiple factors, from intramolecular effects such as bond dissociation energy, oxygen balance, and the electrostatic potential of reactive functional groups, to larger scale effects, such as crystal structure and hot spot formation. We have developed derivatives of the explosive pentaerythritol tetranitrate (PETN) and examined them experimentally and theoretically, in order to better understand which properties influence sensitivity. With this molecular framework, we can evaluate how small changes to the structure of the molecule influence qualities such as oxygen balance, heat of formation, heat capacity, compressibility, crystal packing, and hydrogen bonding, through techniques such as differential scanning calorimetry, x-ray crystallography, and atomistic simulation. We have also used small-scale sensitivity testing as an initial tool to screen for large and consistent differences in handling sensitivity. We will discuss the many factors that contribute to sensitivity in this series of systematically-modified molecules as well as in existing well-studied explosive systems, such as triaminotrinitrobenzene (TATB) and nitroglycerin (NG). In collaboration with: Thomas Myers, Marc Cawkwell, Edward Kober, Bryce Tappan, Geoffrey Brown, Mary Sandstrom, LOS ALAMOS NATL LAB.

Synthesis and Characterization of Diglycerol Tetranitrate (DGTN)—An Energetic Plasticizer for Use in Explosive and Propellant Formulations

NASA Astrophysics Data System (ADS)

Straessler, Nicholas; Lee, Manfai

2017-01-01

Diglycerol was nitrated using mixed acid conditions to give diglycerol tetranitrate and related coproducts. The product mixture was extracted in situ with methylene chloride and analyzed by 1H- and 13C-NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and high-performance liquid chromatography-mass spectrometry (HPLC-MS). Results showed that the product mixture was a combination of two isomers of diglycerol tetranitrate, triglycerol pentanitrate, cyclotriglycerol trinitrate, and diglycerol trinitrate. The mixture of products is explained by the composition of the starting material and by associated side reactions that occur during nitration. This synthesis and analytical data will aid in better understanding diglycerol tetranitrate as a plasticizer in explosive and propellant formulations.

Direct Analysis in Real Time Mass Spectrometry of Potential By-Products from Homemade Nitrate Ester Explosive Synthesis

PubMed Central

Sisco, Edward; Forbes, Thomas P.

2016-01-01

This work demonstrates the coupling of direct analysis in real time (DART) ionization with time-of-flight mass spectrometry (MS) in an off-axis configuration for the trace detection and analysis of potential partially nitrated and dimerized by-products of homemade nitrate ester explosive synthesis. Five compounds relating to the synthesis of nitroglycerin (NG) and pentaerythritol tetranitrate (PETN) were examined. Deprotonated ions and adducts with molecular oxygen, nitrite, and nitrate were observed in the mass spectral responses of these compounds. A global optimum temperature of 350 °C for the by-products investigated here, enabled single nanogram to sub nanogram trace detection. Matrix effects were examined through a series of mixtures containing one or more compounds (sugar alcohol precursors, by-products, and/or explosives) across a range of mass loadings. The explosives MS responses experienced competitive ionization in the presence of all by-products. The magnitude of this influence corresponded to both the degree of by-product nitration and the relative mass loading of the by-product to the explosive. This work provides a characterization of potential by-products from homemade nitrate ester synthesis, including matrix effects and potential challenges that might arise from the trace detection of homemade explosives (HMEs) containing impurities. Detection and understanding of HME impurities and complex mixtures may provide valuable information for the screening and sourcing of homemade nitrate ester explosives. PMID:26838397

Determining the effects of routine fingermark detection techniques on the subsequent recovery and analysis of explosive residues on various substrates.

PubMed

King, Sam; Benson, Sarah; Kelly, Tamsin; Lennard, Chris

2013-12-10

An offender who has recently handled bulk explosives would be expected to deposit latent fingermarks that are contaminated with explosive residues. However, fingermark detection techniques need to be applied in order for these fingermarks to be detected and recorded. Little information is available in terms of how routine fingermark detection methods impact on the subsequent recovery and analysis of any explosive residues that may be present. If an identifiable fingermark is obtained and that fingermark is found to be contaminated with a particular explosive then that may be crucial evidence in a criminal investigation (including acts of terrorism involving improvised explosive devices). The principal aims of this project were to investigate: (i) the typical quantities of explosive material deposited in fingermarks by someone who has recently handled bulk explosives; and (ii) the effects of routine fingermark detection methods on the subsequent recovery and analysis of explosive residues in such fingermarks. Four common substrates were studied: paper, glass, plastic (polyethylene plastic bags), and metal (aluminium foil). The target explosive compounds were 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), as well as chlorate and nitrate ions. Recommendations are provided in terms of the application of fingermark detection methods on surfaces that may contain explosive residues. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Imaging indicator for ESD safety testing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whinnery, LeRoy L.,; Nissen, April; Keifer, Patrick N.

2013-05-01

This report describes the development of a new detection method for electrostatic discharge (ESD) testing of explosives, using a single-lens reflex (SLR) digital camera and a 200-mm macro lens. This method has demonstrated several distinct advantages to other current ESD detection methods, including the creation of a permanent record, an enlarged image for real-time viewing as well as extended periods of review, and ability to combine with most other Go/No-Go sensors. This report includes details of the method, including camera settings and position, and results with wellcharacterized explosives PETN and RDX, and two ESD-sensitive aluminum powders.

Simulation of Turbulent Combustion Fields of Shock-Dispersed Aluminum Using the AMR Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Bell, J B; Beckner, V E

2006-11-02

We present a Model for simulating experiments of combustion in Shock-Dispersed-Fuel (SDF) explosions. The SDF charge consisted of a 0.5-g spherical PETN booster, surrounded by 1-g of fuel powder (flake Aluminum). Detonation of the booster charge creates a high-temperature, high-pressure source (PETN detonation products gases) that both disperses the fuel and heats it. Combustion ensues when the fuel mixes with air. The gas phase is governed by the gas-dynamic conservation laws, while the particle phase obeys the continuum mechanics laws for heterogeneous media. The two phases exchange mass, momentum and energy according to inter-phase interaction terms. The kinetics model usedmore » an empirical particle burn relation. The thermodynamic model considers the air, fuel and booster products to be of frozen composition, while the Al combustion products are assumed to be in equilibrium. The thermodynamic states were calculated by the Cheetah code; resulting state points were fit with analytic functions suitable for numerical simulations. Numerical simulations of combustion of an Aluminum SDF charge in a 6.4-liter chamber were performed. Computed pressure histories agree with measurements.« less

Thermal safety characterization on PETN, PBX-9407, LX-10-2, LX-17-1 and detonator in the LLNL's P-ODTX system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, P. C.; Strout, S.; Reynolds, J. G.

Incidents caused by fire and other thermal events can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Thus, it is important to understand the response of energetic materials to thermal insults. The One-Dimensional-Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) has been used for decades to characterize thermal safety of energetic materials. In this study, an integration of a pressure monitoring element has been added into the ODTX system (P-ODTX) to perform thermal explosion (cook-off) experiments (thermal runaway) on PETN powder, PBX-9407, LX-10-2, LX-17-1, and detonator samples (cupmore » tests). The P-ODTX testing generates useful data (thermal explosion temperature, thermal explosion time, and gas pressures) to assist with the thermal safety assessment of relevant energetic materials and components. This report summarizes the results of P-ODTX experiments that were performed from May 2015 to July 2017. Recent upgrades to the data acquisition system allows for rapid pressure monitoring in microsecond intervals during thermal explosion. These pressure data are also included in the report.« less

Direct analysis in real time mass spectrometry of potential by-products from homemade nitrate ester explosive synthesis.

PubMed

Sisco, Edward; Forbes, Thomas P

2016-04-01

This work demonstrates the coupling of direct analysis in real time (DART) ionization with time-of-flight mass spectrometry (MS) in an off-axis configuration for the trace detection and analysis of potential partially nitrated and dimerized by-products of homemade nitrate ester explosive synthesis. Five compounds relating to the synthesis of nitroglycerin (NG) and pentaerythritol tetranitrate (PETN) were examined. Deprotonated ions and adducts with molecular oxygen, nitrite, and nitrate were observed in the mass spectral responses of these compounds. A global optimum temperature of 350 °C for the by-products investigated here enabled single nanogram to sub nanogram trace detection. Matrix effects were examined through a series of mixtures containing one or more compounds (sugar alcohol precursors, by-products, and/or explosives) across a range of mass loadings. The explosives MS responses experienced competitive ionization in the presence of all by-products. The magnitude of this influence corresponded to both the degree of by-product nitration and the relative mass loading of the by-product to the explosive. This work provides a characterization of potential by-products from homemade nitrate ester synthesis, including matrix effects and potential challenges that might arise from the trace detection of homemade explosives (HMEs) containing impurities. Detection and understanding of HME impurities and complex mixtures may provide valuable information for the screening and sourcing of homemade nitrate ester explosives. Published by Elsevier B.V.

Spectroscopic detection of exogenous materials in latent fingerprints treated with powders and lifted off with adhesive tapes.

PubMed

Banas, A; Banas, K; Breese, M B H; Loke, J; Lim, S K

2014-07-01

Fingerprint evidence offers great value to criminal investigations since it is an internationally recognized and established means of human identification. With recent advances in modern technology, scientists have started analyzing not only the ridge patterns of fingerprints but also substances which can be found within them. The aim of this work was to determine whether Fourier transform infrared (FTIR) spectromicroscopy could be used to detect contamination in a fingerprint which was dusted with powder (a technique already recognized as an effective and reliable method for developing latent fingerprints) and subsequently lifted off with adhesive tape. Explosive materials (pentaerythritol tetranitrate, C-4, TNT) and noncontrolled substances (sugar, aspirin) were used to prepare contaminated fingerprints on various substrates. Freshly deposited fingermarks with powders which were lifted off with adhesive tapes (provided by Singapore Police Force) were analyzed using a Bruker Hyperion 2000 microscope at the ISMI beamline (Singapore Synchrotron Light Source) with an attenuated total reflection objective. FTIR spectroscopy is a nondestructive technique which requires almost no sample preparation. Further, the fingerprint under analysis remains in pristine condition, allowing subsequent analysis if necessary. All analyzed substances were successfully distinguished using their FTIR spectra in powdered and lifted fingerprints. This method has the potential to significantly impact forensic science by greatly enhancing the information that can be obtained from the study of fingerprints.

Deflagration Rates and Molecular Bonding Trends of Statically Compressed Secondary Explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaug, J M; Foltz, M F; Hart, E

2010-03-09

We discuss our measurements of the chemical reaction propagation rate as a function of pressure. Materials investigated have included CL-20, HMX, TATB, and RDX crystalline powders, LX-04, Comp B, and nitromethane. The anomalous correspondence between crystal structure, including in some instances isostructural phase transitions, on pressure-dependant RPRs of TATB, HMX, Nitromethane, CL-20, and PETN have been elucidated using micro-IR and -Raman spectroscopies. Here we specifically highlight pressure-dependent physicochemical mechanisms affecting the deflagration rate of nitromethane and epsilon-CL-20. We find that pressure induced splitting of symmetric stretch NO{sub 2} vibrations can signal the onset of increasingly more rapid combustion reactions.

A study of the composition of the products of laser-induced breakdown of hexogen, octogen, pentrite and trinitrotoluene using selected ion flow tube mass spectrometry and UV-Vis spectrometry.

PubMed

Sovová, Kristýna; Dryahina, Kseniya; Spanel, Patrik; Kyncl, Martin; Civis, Svatopluk

2010-05-01

Four types of explosives were studied using a combination of Laser Induced Breakdown Spectroscopy (LIBS) and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (ArF excimer laser) as the energy source to convert small amounts samples into plasma and to produce the emission from their molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three precursor ions, with the capability to determine concentrations of trace gases and vapours of volatile organic compounds in real time. This is the first time that SIFT-MS has been used to study the release of NO, NO(2), HCN, HNO(3), HONO, HCHO and C(2)H(2) after a laser-induced breakdown of pure explosive compounds HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclo-octane), RDX (1,3,5-trinitro-2-oxo-1,3,5-triazacyclo-hexane), PETN (pentaerithrityl-tetranitrate) and TNT (2,4,6-trinitrotoluene) in solid form. The radiation emitted after excitation was analysed using a time resolving UV-Vis spectrometer with a ICCD detector. Electronic bands of the CN radical (388 nm), the Swan system of the C(2) radical (512 nm), the NH radical (336 nm), the OH radical (308.4 nm) and atomic lines of oxygen, nitrogen and hydrogen were identified. Vibrational and excitation temperatures were determined from the intensity distributions and a scheme of chemical reactions responsible for the formation of the observed species was proposed.

Ignition and growth modeling of detonation reaction zone experiments on single crystals of PETN and HMX

NASA Astrophysics Data System (ADS)

White, Bradley W.; Tarver, Craig M.

2017-01-01

It has long been known that detonating single crystals of solid explosives have much larger failure diameters than those of heterogeneous charges of the same explosive pressed or cast to 98 - 99% theoretical maximum density (TMD). In 1957, Holland et al. demonstrated that PETN single crystals have failure diameters of about 8 mm, whereas heterogeneous PETN charges have failure diameters of less than 0.5 mm. Recently, Fedorov et al. quantitatively determined nanosecond time resolved detonation reaction zone profiles of single crystals of PETN and HMX by measuring the interface particle velocity histories of the detonating crystals and LiF windows using a PDV system. The measured reaction zone time durations for PETN and HMX single crystal detonations were approximately 100 and 260 nanoseconds, respectively. These experiments provided the necessary data to develop Ignition and Growth (I&G) reactive flow model parameters for the single crystal detonation reaction zones. Using these parameters, the calculated unconfined failure diameter of a PETN single crystal was 7.5 +/- 0.5 mm, close to the 8 mm experimental value. The calculated failure diameter of an unconfined HMX single crystal was 15 +/- 1 mm. The unconfined failure diameter of an HMX single crystal has not yet been determined precisely, but Fedorov et al. detonated 14 mm diameter crystals confined by detonating a HMX-based plastic bonded explosive (PBX) without initially overdriving the HMX crystals.

Spectroscopic signatures of PETN in contact with sand particles

NASA Astrophysics Data System (ADS)

Ballesteros, Luz M.; Herrera, Gloria M.; Castro, Miguel E.; Briano, Julio; Mina, Nairmen; Hernandez-Rivera, Samuel P.

2005-06-01

The detection of explosive materials is not only important as an issue in landmines but also for global security reasons, unexploded ordnance, and Improvised Explosive Devices detection. In such areas, explosives detection has played a central role in ensuring the safety of the lives of citizens in many countries. Raman Spectroscopy is a well established tool for vibrational spectroscopic analysis and can be applied to the field of explosives identification and detection. The analysis of PETN is important because it is used in laminar form or mixed with RDX to manufacture Semtex plastic explosive and in the fabrication of Improvised Explosive Devices (IEDs). Our investigation is focused on the study of spectroscopic signatures of PETN in contact with soil. Ottawa sand mixed in different proportions with PETN together with the study of the influence of pH, temperature, humidity, and UV light on the vibrational signatures of the mixtures constitute the core of the investigation. The results reveal that the characteristic bands of PETN are not significantly shifted but rather appear constant with respect of the ubiquitous band of sand (~463 cm-1). These results will make possible the development of highly sensitive sensors for detection of explosives materials and IDEs.

Integrated Data Collection Analysis (IDCA) Program - NaClO 3/Icing Sugar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of a mixture of NaClO 3 and icing sugar—NaClO 3/icing sugar mixture. The mixture was found to: be more sensitive than RDX but less sensitive than PETN in impact testing (180-grit sandpaper); be more sensitive than RDX and about the same sensitivity as PETN in BAM fiction testing; be less sensitive than RDX and PETN except for one participant found themore » mixture more sensitive than PETN in ABL ESD testing; and to have one to three exothermic features with the lowest temperature event occurring at ~ 160°C always observed in thermal testing. Variations in testing parameters also affected the sensitivity.« less

In-situ monitoring of flow-permeable surface area of high explosive powder using small sample masses

DOE PAGES

Maiti, Amitesh; Han, Yong; Zaka, Fowzia; ...

2015-02-17

To ensure good performance of high explosive devices over long periods of time, initiating powders need to maintain their specific surface area within allowed margins during the entire duration of deployment. A common diagnostic used in this context is the Fisher sub-sieve surface area (FSSA). Furthermore, commercial permeametry instruments measuring the FSSA requires the utilization of a sample mass equal to the crystal density of the sample material, an amount that is often one or two orders of magnitude larger than the typical masses found in standard detonator applications. Here we develop a customization of the standard device that canmore » utilize just tens of milligram samples, and with simple calibration yield FSSA values at ac curacy levels comparable to the standard apparatus. This necessitated a newly designed sample holder, made from a material of low coefficient of thermal expansion, which is conveniently transferred between an aging chamber and a re-designed permeametry tube. This improves the fidelity of accelerated aging studies by allowing measurement on the same physical sample at various time - instants during the aging process, and by obviating the need for a potentially FSSA-altering powder re-compaction step. We used the customized apparatus to monitor the FSSA evolution of a number of undoped and homolog-doped PETN powder samples that were subjected to artificial aging for several months at elevated temperatures. These results, in conjunction with an Arrhenius-based aging model were used to assess powder-coarsening - rates under long-term storage.« less

Coefficient of Thermal Expansion of Pressed PETN Pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Darla Graff; DeLuca, Racci

2015-03-11

The PETN single crystal coefficient of thermal expansion (CTE) values were measured and reported by Cady in 1972 [1] over the temperature range of -160 to 100°C. Measurements were made in the (001) and (100) crystallographic directions, see Figure 1 (a replicate of Figure 1 from the Cady paper). Cady used his single-crystal data to calculate the linear CTE for a randomly-oriented multi-crystal pressing of PETN, and his values ranged from 76.5 με/°C (at 20°C) to 89.9 5 με/°C (at 90°C).

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), its properties and initiation reactivity.

PubMed

Klasovitý, Dusan; Zeman, Svatopluk; Růzicka, Ales; Jungová, Marcela; Rohác, Michal

2009-05-30

Using the (15)N NMR chemical shifts of nitrogen atoms in nitramino groups of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (bicyclo-HMX or BCHMX) and additional 10 nitramines, we have assessed its reactivity in detonation, under the influence of impact, and by action of electric spark. It is stated that the thermal stability of BCHMX is higher than that of 1,3,5-trinitro-1,3,5-triazinane (RDX). The longest NN bond in the BCHMX molecule (1.412(4)A) is the cause for its higher impact reactivity, which is at the level of that of penterythritol tetranitrate (PETN). In the experimentally determined detonation velocity, BCMX can be slightly better performing than RDX. From the standpoint of friction sensitivity, BCHMX is similar to 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). Attention was also focused on the solubility-temperature dependence of BCHMX in acetone, acetonitrile, ethyl acetate, dimethyl sulfoxide, tetrahydrofurane, and nitromethane. X-ray crystallographic study of BCHMX (C(4)H(6)N(8)O(8), M(r)=294.17), has been carried out at the temperature of 150K with the following results: a=8.5430(8), b=6.9480(6), c=8.7780(8)A, alpha=90.0(7) degrees , beta=102.452(11) degrees , gamma=90.0(9) degrees , V=508.777(8)A(3), Z=2, D(x)=1.920 g cm(-3), lambda(Mo Ka)=0.71073A, micro=0.169 cm(-1), F(000)=856, final R=0.0414 for 1254 independent observed reflections. In the BCHMX crystal there were found more short contacts in the molecular crystal of BCHMX data of Gilardi creating extensive supramolecular architecture.

Use of Mass Spectrometric Vapor Analysis To Improve Canine Explosive Detection Efficiency.

PubMed

Ong, Ta-Hsuan; Mendum, Ted; Geurtsen, Geoff; Kelley, Jude; Ostrinskaya, Alla; Kunz, Roderick

2017-06-20

Canines remain the gold standard for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of understanding of the canine's odor environment, which is dynamic and typically contains multiple odorants. Existing methodology assumes that the handler's intention is an adequate surrogate for actual knowledge of the odors cuing the canine, but canines are easily exposed to unintentional explosive odors through training material cross-contamination. A sensitive, real-time (∼1 s) vapor analysis mass spectrometer was developed to provide tools, techniques, and knowledge to better understand, train, and utilize canines. The instrument has a detection library of nine explosives and explosive-related materials consisting of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD), and cyclohexanone, with detection limits in the parts-per-trillion to parts-per-quadrillion range by volume. The instrument can illustrate aspects of vapor plume dynamics, such as detecting plume filaments at a distance. The instrument was deployed to support canine training in the field, detecting cross-contamination among training materials, and developing an evaluation method based on the odor environment. Support for training material production and handling was provided by studying the dynamic headspace of a nonexplosive HMTD training aid that is in development. These results supported existing canine training and identified certain areas that may be improved.

40 CFR 799.5085 - Chemical testing requirements for certain high production volume chemicals.

Code of Federal Regulations, 2011 CFR

2011-07-01

... diluted in water or tested as a stabilized mixture with an appropriate stabilizer (e.g., D-lactose monohydrate is the stabilizer in PETN, NF which is a mixture of 20% by weight PETN and 80% by weight D-lactose...

Temperature evolution in silver nanoparticle doped PETN composite

NASA Astrophysics Data System (ADS)

Kameswari, D. P. S. L.; Kiran, P. Prem

2018-04-01

Optical absorption and the associated spatio-temporal evolution of temperature silver nanoparticles doped energetic material composite is presented. Silver nanoparticles of radii 10 - 150 nm are doped in Penta Erythrtol Tetra Nitrate (PETN), a secondary energetic material to form the composite materials. Of all the composites the ones doped with 35 nm sized nanoparticles have shown maximum absorption at excitation wavelength of 532 nm. The spatio-temporal evolution of temperature within these composites up on excitation with ns laser pulses of energy density 0.5 J/cm2 is studied. The role of particle sizes on the temperature of composites is studied and a maximum temperature of 2200 K at the nanoparticle interface is observed for 35 nm doped PETN composite.

Surface characterization of an energetic material, pentaerythritoltetranitrate (PETN), having a thin coating achieved through a starved addition microencapsulation technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worley, C.M.

The objective of this research was to: (1) determine the nature of a thin coating on an explosive material which was applied using a starved addition microencapsulation technique, (2) understand the coating/crystal bond, and (3) investigate the wettability/adhesion of plastic/solvent combinations using the coating process. The coating used in this work was a Firestone Plastic Company copolymer (FPC-461) of vinylchloride/trifluorochloroethylene in a 1.5/1.0 weight ratio. The energetic explosive examined was pentaerythritoltetranitrate (PETN). The coating process used was starved addition followed by a solvent evaporation technique. Surface analytical studies, completed for characterization of the coating process, show (1) evidence that themore » polymer coating is present, but not continuous, over the surface of PETN; (2) the average thickness of the polymer coating is between 16-32 A and greater than 44 A, respectively, for 0.5 and 20 wt % coated PETN; (3) no changes in surface chemistry of the polymer or the explosive material following microencapsulation; and (4) the presence of explosive material on the surface of 0.5 wt % FPC-461 coated explosives. 5 refs., 15 figs., 6 tabs.« less

Modelling of Deflagration to Detonation Transition in Porous PETN of Density 1.4 g / cc with HERMES

NASA Astrophysics Data System (ADS)

Reaugh, John; Curtis, John; Maheswaran, Mary-Ann

2017-06-01

The modelling of Deflagration to Detonation Transition in explosives is a severe challenge for reactive burn models because of the complexity of the physics; there is mechanical and thermal interaction of the gaseous burn products with the burning porous matrix, with resulting compaction, shock formation and subsequent detonation. Experiments on the explosive PETN show a strong dependence of run distance to detonation on porosity. The minimum run distance appears to occur when the density is approximately 1.4 g / cc. Recent research on the High Explosive Response to Mechanical Stimulation (HERMES) model for High Explosive Violent Reaction has included the development of a model for PETN at 1.4 g / cc., which allows the prediction of the run distance in the experiments for PETN at this density. Detonation and retonation waves as seen in the experiment are evident. The HERMES simulations are analysed to help illuminate the physics occurring in the experiments. JER's work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344 and partially funded by the Joint US DoD/DOE Munitions Technology Development Program. LLNL-ABS-723537.

The Fundamental Chemistry and Physics of Munitions under Extreme Conditions

DTIC Science & Technology

2011-02-01

I. I. Oleynik, S. V. Zybin, and C. T. White, “Density Functional Theory Calculations of Solid Nitromethane under Hydrostatic and Uniaxial...White (NRL), Ivan Oleynik (USF): anisotropic nonlinear elasticity and equations of states of crystalline EM (PETN, RDX, HMX, TATB, nitromethane ...and nitromethane ;  Aidan Thompson (SNL): shock-to-detonation transition in PETN and CL-20;  Ronnie Kosloff (Hebrew University of Jerusalem

Forensic analysis of explosives using isotope ratio mass spectrometry (IRMS)--preliminary study on TATP and PETN.

PubMed

Benson, Sarah J; Lennard, Christopher J; Maynard, Philip; Hill, David M; Andrew, Anita S; Roux, Claude

2009-06-01

The application of isotopic techniques to investigations requiring the provision of evidence to a Court is limited. The objective of this research was to investigate the application of light stable isotopes and isotope ratio mass spectrometry (IRMS) to solve complex forensic cases by providing a level of discrimination not achievable utilising traditional forensic techniques. Due to the current threat of organic peroxide explosives, such as triacetone triperoxide (TATP), research was undertaken to determine the potential of IRMS to differentiate samples of TATP that had been manufactured utilising different starting materials and/or manufacturing processes. In addition, due to the prevalence of pentaerythritoltetranitrate (PETN) in detonators, detonating cord, and boosters, the potential of the IRMS technique to differentiate PETN samples from different sources was also investigated. Carbon isotope values were measured in fourteen TATP samples, with three definite groups appearing in the initial sample set based on the carbon data alone. Four additional TATP samples (in a second set of samples) were distinguishable utilising the carbon and hydrogen isotopic compositions individually, and also in combination with the oxygen isotope values. The 3D plot of the carbon, oxygen and hydrogen data demonstrated the clear discrimination of the four samples of TATP. The carbon and nitrogen isotope values measured from fifteen PETN samples, allowed samples from different sources to be readily discriminated. This paper demonstrates the successful application of IRMS to the analysis of explosives of forensic interest to assist in discriminating samples from different sources. This research represents a preliminary evaluation of the IRMS technique for the measurement of stable isotope values in TATP and PETN samples, and supports the dedication of resources for a full evaluation of this application in order to achieve Court reportable IRMS results.

Molecular Simulations of Dynamic Processes of Solid Explosives

DTIC Science & Technology

2004-12-01

compression. Therefore, we analyzed the dynamics of the energetic crystals RDX , HMX , HNIW and PETN under hydrostatic compression conditions using...for the RDX , HMX and HNIW crystals were found in good agreement with experimental values over the entire range of pressures investigated...Theoretical studies of the hydrostatic compression of RDX , HMX , HNIW, and PETN crystals, J. Phys. Chem. B 103, 6783. scu, D. C.; Rice, B. M. and

Response of Primary Explosives to Gaseous Discharges in an Improved Approaching-Electrode Electrostatic Sensitivity Apparatus

DTIC Science & Technology

1976-10-01

and Identify by block number) This report describes an improved, approaching-needle electrostatic sensitivity apparatus as well as the...category. Thus, basic lead styphnate, RD1333 lead azide, dextrinated lead azide and tetracene all ignited. But, as expected, tetryl, PETN, superfine PETN... dextrinated lead azide obtained using the same apparatus and procedure and conducted at the same time. Sample Preparation, Electrode Replacement, and

Improved accuracy in high-temperature conversion elemental analyzer δ18O measurements of nitrogen-rich organics.

PubMed

Hunsinger, Glendon B; Stern, Libby A

2012-03-15

The use of high-temperature conversion (HTC) reduction systems interfaced with isotope ratio mass spectrometers for δ(18)O measurements of nitrogen-containing organic materials is complicated by isobaric interference from (14)N(16)O(+). This ion is produced in the ion source when N(2) reacts with trace oxygen shifting the m/z 30 baseline prior to elution of CO. We compared adaptations to a typical HTC system (TC/EA) to determine the best method to measure the δ(18)O values of nitrogen-rich organic substrates including: (1) 0.6 and 1.5 m 5 Å molecular sieve GC columns; (2) reduction of N(2) peak via He dilution; and (3) diversion of N(2) to waste via an automated four-port valve. These methods were applied to caffeine (IAEA-600), glycine, 4-nitroacetanilide, pentaerythritol tetranitrate (PETN) and cyclotrimethylene trinitramine (RDX), as well as pure and sodium azide-doped benzoic acid (IAEA-601) and sucrose (IAEA-CH6). The efficiency of N(2) production in the HTC interface was highly variable among these compounds. Both the longer column and the dilutor improved, but did not eliminate, the adverse effects of nitrogen. The diversion of N(2) adequately addressed the nitrogen-induced problems as indicated by: (1) consistent m/z 30 background offset between reference and sample CO for both N-free and N-rich materials; (2) production of the highest δ(18)O values; and (3) high correlation between the increase in the δ(18)O values relative to the GC-only measurements and the N(2) peak area. Additional validation would require N-rich oxygen isotope standards for inter-laboratory comparisons. Further, more stringent methodology may improve the poor inter-laboratory δ(18)O reproducibility of IAEA-600. Published in 2012 by John Wiley & Sons, Ltd.

Integration of paper spray ionization high-field asymmetric waveform ion mobility spectrometry for forensic applications.

PubMed

Tsai, Chia-Wei; Tipple, Christopher A; Yost, Richard A

2018-04-15

Paper spray ionization (PSI) is an attractive ambient ionization source for mass spectrometry (MS) since it allows the combination of surface sampling and ionization. The minimal sample preparation inherent in this approach greatly reduces the time needed for analysis. However, the ions generated from interfering compounds in the sample and the paper substrate may interfere with the analyte ions. Therefore, the integration of PSI with high-field asymmetric ion mobility spectrometry (FAIMS) is of significant interest since it should reduce the background ions entering the mass analyzer without complicating the analysis or increasing analysis time. Here we demonstrate the integration of PSI with FAIMS/MS and its potential for analysis of samples of forensic interest. In this work, the parameters that can influence the integration, including sampling and ionization by paper spray, the FAIMS separation of analytes from each other and background interferences, and the length of time that a usable signal can be observed for explosives on paper, were evaluated with the integrated system. In the negative ion analysis of 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), amounts as low as 1 ng on paper were readily observed. The successful positive ion separation of a set of illicit drugs including heroin, methamphetamine, and cocaine was also achieved. In addition, the positive ion analysis of the chemical warfare agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP) was evaluated. The integration of PSI-FAIMS/MS was demonstrated for the analyses of explosives in negative ion mode and for illicit drugs and CW simulants in positive mode. Paper background ions that could interfere with these analyses were separated by FAIMS. The compensation voltage of an ion obtained by FAIMS provided an additional identification parameter to be combined with the mass spectrum for each analyte. Copyright © 2018 John Wiley & Sons, Ltd.

Infrared Emission Study of Deformation and Ignition of Energetic Materials (IMAD HE Program Progress Report)

DTIC Science & Technology

1986-05-31

of magnitude differences between PBXN -103, PBXW-115(Q), H6, PBXW-109(Q) and PBXN - 106 for a given test Table 1. (IR Emission data shown in Figure 14...AND ACCELEROMETER RESPONSE (B) OF PETN IMPACTED WITH 5.5 m/sec VELOCITY . . . . . . . . . . . . . . . 23 10 PBXN -103 IMPACTED AT 19 m/sec. IR...duration of the experiments. Impact experiments were conducted on NaCl, NH4C10 4 , RDX, PETN, and PBXN -103, as well as several composite materials. The

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hobbs, Michael L.

We previously developed a PETN thermal decomposition model that accurately predicts thermal ignition and detonator failure [1]. This model was originally developed for CALORE [2] and required several complex user subroutines. Recently, a simplified version of the PETN decomposition model was implemented into ARIA [3] using a general chemistry framework without need for user subroutines. Detonator failure was also predicted with this new model using ENCORE. The model was simplified by 1) basing the model on moles rather than mass, 2) simplifying the thermal conductivity model, and 3) implementing ARIA’s new phase change model. This memo briefly describes the model,more » implementation, and validation.« less

A new eye-safe UV Raman spectrometer for the remote detection of energetic materials in fingerprint concentrations: Characterization by PCA and ROC analyzes.

PubMed

Almaviva, Salvatore; Chirico, Roberto; Nuvoli, Marcello; Palucci, Antonio; Schnürer, Frank; Schweikert, Wenka

2015-11-01

We report the results of proximal Raman investigations at a distance of 7 m, to detect traces of explosives (from 0.1 to 0.8 mg/cm(2)) on common clothes with a new eye-safe apparatus. The instrument excites the target with a single laser shot of few ns (10(-9)s) in the UV range (laser wavelength 266 nm) detecting energetic materials like Pentaerythritol tetranitrate (PETN), Trinitrotoluene (TNT), Urea Nitrate (UN) and Ammonium Nitrate (AN). Samples were prepared using a piezoelectric-controlled plotter device to realize well-calibrated amounts of explosives on several cm(2). Common fabrics and tissues such as polyester, polyamide and leather were used as substrates, representative of base-materials used in the production of jackets or coats. Other samples were prepared by touching the substrate with a silicon finger contaminated with explosives, to simulate a spot left by contaminated hands on a jacket or bag during the preparation of an improvised explosive device (IED) by a terrorist. The observed Raman signals showed some peculiar molecular bands of the analyzed compounds, allowing us to identify and discriminate them with high sensitivity and selectivity, also in presence of the interfering signal from the underlying fabric. A dedicated algorithm was developed to remove noise and fluorescence background from the single laser shot spectra and an automatic spectral recognition procedure was also implemented, evaluating the intensity of the characteristic Raman bands of each explosive and allowing their automatic classification. Principal component analysis (PCA) was used to show the discrimination potentialities of the apparatus on different sets of explosives and to highlight possible criticalities in the detection. Receiver operating characteristic (ROC) curves were used to discuss and quantify the sensitivity and the selectivity of the proposed recognition procedure. To our knowledge the developed device is at the highest sensitivity nowadays achievable in the field of eye-safe, Raman devices for proximal detection. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of Van Der Waals Density Functional Theory to Study Physical Properties of Energetic Materials

NASA Astrophysics Data System (ADS)

Conroy, M. W.; Budzevich, M. M.; Lin, Y.; Oleynik, I. I.; White, C. T.

2009-12-01

An empirical correction to account for van der Waals interactions based on the work of Neumann and Perrin [J. Phys. Chem. B 109, 15531 (2005)] was applied to density functional theory calculations of energetic molecular crystals. The calculated equilibrium unit-cell volumes of FOX-7, β-HMX, solid nitromethane, PETN-I, α-RDX, and TATB show a significant improvement in the agreement with experimental results. Hydrostatic-compression simulations of β-HMX, PETN-I, and α-RDX were also performed. The isothermal equations of state calculated from the results show increased agreement with experiment in the pressure intervals studied.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manaa, M. Riad; Fried, Laurence E.; Kuo, I-Feng W.

We report gas-phase enthalpies of formation for the set of energetic molecules NTO, DADE, LLM-105, TNT, RDX, TATB, HMX, and PETN using the G2, G3, G4, and ccCA-PS3 quantum composite methods. Calculations for HMX and PETN hitherto represent the largest molecules attempted with these methods. G3 and G4 calculations are typically close to one another, with a larger difference found between these methods and ccCA-PS3. Furthermore there is significant uncertainty in experimental values, the mean absolute deviation between the average experimental value and calculations are 12, 6, 7, and 3 kcal/mol for G2, G3, G4, and ccCA-PS3, respectively.

Direct Real-Time Detection of Vapors from Explosive Compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ewing, Robert G.; Clowers, Brian H.; Atkinson, David A.

2013-10-03

The real-time detection of vapors from low volatility explosives including PETN, tetryl, RDX and nitroglycerine along with various compositions containing these substances is demonstrated. This was accomplished with an atmospheric flow tube (AFT) using a non-radioactive ionization source and coupled to a mass spectrometer. Direct vapor detection was demonstrated in less than 5 seconds at ambient temperature without sample pre-concentration. The several seconds of residence time of analytes in the AFT provides a significant opportunity for reactant ions to interact with analyte vapors to achieve ionization. This extended reaction time, combined with the selective ionization using the nitrate reactant ionsmore » (NO3- and NO3-•HNO3), enables highly sensitive explosives detection. Observed signals from diluted explosive vapors indicate detection limits below 10 ppqv using selected ion monitoring (SIM) of the explosive-nitrate adduct at m/z 349, 378, 284 and 289 for tetryl, PETN, RDX and NG respectively. Also provided is a demonstration of the vapor detection from 10 different energetic formulations, including double base propellants, plastic explosives and commercial blasting explosives using SIM for the NG, PETN and RDX product ions.« less

Direct real-time detection of vapors from explosive compounds.

PubMed

Ewing, Robert G; Clowers, Brian H; Atkinson, David A

2013-11-19

The real-time detection of vapors from low volatility explosives including PETN, tetryl, RDX, and nitroglycerine along with various compositions containing these substances was demonstrated. This was accomplished with an atmospheric flow tube (AFT) using a nonradioactive ionization source coupled to a mass spectrometer. Direct vapor detection was accomplished in less than 5 s at ambient temperature without sample preconcentration. The several seconds of residence time of analytes in the AFT provided a significant opportunity for reactant ions to interact with analyte vapors to achieve ionization. This extended reaction time, combined with the selective ionization using the nitrate reactant ions (NO3(-) and NO3(-)·HNO3), enabled highly sensitive explosives detection from explosive vapors present in ambient laboratory air. Observed signals from diluted explosive vapors indicated detection limits below 10 ppqv using selected ion monitoring (SIM) of the explosive-nitrate adduct at m/z 349, 378, 284, and 289 for tetryl, PETN, RDX, and NG, respectively. Also provided is a demonstration of the vapor detection from 10 different energetic formulations sampled in ambient laboratory air, including double base propellants, plastic explosives, and commercial blasting explosives using SIM for the NG, PETN, and RDX product ions.

76 FR 64974 - Commerce in Explosives; List of Explosive Materials (2011R-18T)

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-19

... [dinitropentano nitrile]. Dynamite. E EDDN [ethylene diamine dinitrate]. EDNA [ethylenedinitramine]. Ednatol. EDNP [ethyl 4,4-dinitropentanoate]. EGDN [ethylene glycol dinitrate]. Erythritol tetranitrate explosives..., trinitroglycerine]. Nitroglycide. Nitroglycol [ethylene glycol dinitrate, EGDN]. Nitroguanidine explosives...

77 FR 58410 - Commerce in Explosives; List of Explosive Materials (2012R-10T)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-20

... [dinitropentano nitrile]. Dynamite. E EDDN [ethylene diamine dinitrate]. EDNA [ethylenedinitramine]. Ednatol. EDNP [ethyl 4,4-dinitropentanoate]. EGDN [ethylene glycol dinitrate]. Erythritol tetranitrate explosives..., RNG, nitro, glyceryl trinitrate, trinitroglycerine]. Nitroglycide. Nitroglycol [ethylene glycol...

Long-Wave Infrared (LWIR) Molecular Laser-Induced Breakdown Spectroscopy (LIBS) Emissions of Thin Solid Explosive Powder Films Deposited on Aluminum Substrates.

PubMed

Yang, Clayton S-C; Jin, Feng; Trivedi, Sudhir B; Brown, Ei E; Hommerich, Uwe; Tripathi, Ashish; Samuels, Alan C

2017-04-01

Thin solid films made of high nitro (NO 2 )/nitrate (NO 3 ) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region. A preliminary assessment of the detection limit for a thin film of RDX on aluminum appears to be much lower than 60 µg/cm 2 . This LWIR LIBS setup is capable of rapidly probing and charactering samples without the need for elaborate sample preparation and also offers the possibility of a simultaneous ultraviolet visible and LWIR LIBS measurement.

Results, meta-analysis and a first evaluation of UNOxR, the urinary nitrate-to-nitrite molar ratio, as a measure of nitrite reabsorption in experimental and clinical settings.

PubMed

Tsikas, Dimitrios; Hanff, Erik; Bollenbach, Alexander; Kruger, Ruan; Pham, Vu Vi; Chobanyan-Jürgens, Kristine; Wedekind, Dirk; Arndt, Tanja; Jörns, Anne; Berbée, Jimmy F P; Princen, Hans M G; Lücke, Thomas; Mariotti, François; Huneau, Jean-François; Ückert, Stefan; Frölich, Jürgen C; Lenzen, Sigurd

2018-05-04

We recently found that renal carbonic anhydrase (CA) is involved in the reabsorption of inorganic nitrite (NO 2 - ), an abundant reservoir of nitric oxide (NO) in tissues and cells. Impaired NO synthesis in the endothelium and decreased NO bioavailability in the circulation are considered major contributors to the development and progression of renal and cardiovascular diseases in different conditions including diabetes. Isolated human and bovine erythrocytic CAII and CAIV can convert nitrite to nitrous acid (HONO) and its anhydride N 2 O 3 which, in the presence of thiols (RSH), are further converted to S-nitrosothiols (RSNO) and NO. Thus, CA may be responsible both for the homeostasis of nitrite and for its bioactivation to RSNO/NO. We hypothesized that enhanced excretion of nitrite in the urine may contribute to NO-related dysfunctions in the renal and cardiovascular systems, and proposed the urinary nitrate-to-nitrite molar ratio, i.e., U NOx R, as a measure of renal CA-dependent excretion of nitrite. Based on results from clinical and experimental animal studies, here, we report on a first evaluation of U NOx R. We determined U NOx R values in preterm neonates, healthy children, and adults, in children suffering from type 1 diabetes mellitus (T1DM) or Duchenne muscular dystrophy (DMD), in elderly subjects suffering from chronic rheumatic diseases, type 2 diabetes mellitus (T2DM), coronary artery disease (CAD), or peripheral arterial occlusive disease (PAOD). We also determined U NOx R values in healthy young men who ingested isosorbide dinitrate (ISDN), pentaerythrityl tetranitrate (PETN), or inorganic nitrate. In addition, we tested the utility of U NOx R in two animal models, i.e., the LEW.1AR1-iddm rat, an animal model of human T1DM, and the APOE*3-Leiden.CETP mice, a model of human dyslipidemia. Mean U NOx R values were lower in adult patients with rheumatic diseases (187) and in T2DM patients of the DALI study (74) as compared to healthy elderly adults (660) and healthy young men (1500). The intra- and inter-variabilities of U NOx R were of the order of 50% in young and elderly healthy subjects. U NOx R values were lower in black compared to white boys (314 vs. 483, P = 0.007), which is in line with reported lower NO bioavailability in black ethnicity. Mean U NOx R values were lower in DMD (424) compared to healthy (730) children, but they were higher in T1DM children (1192). ISDN (3 × 30 mg) decreased stronger U NOx R compared to PETN (3 × 80 mg) after 1 day (P = 0.046) and after 5 days (P = 0.0016) of oral administration of therapeutically equivalent doses. In healthy young men who ingested NaNO 3 (0.1 mmol/kg/d), U NOx R was higher than in those who ingested the same dose of NaCl (1709 vs. 369). In LEW.1AR1-iddm rats, mean U NOx R values were lower than in healthy rats (198 vs. 308) and comparable to those in APOE*3-Leiden.CETP mice (151).

Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

DOE PAGES

Chen, Lei; Cui, Hui-Hui; Stavretis, Shelby E.; ...

2016-12-07

We synthesized and studied three mononuclear cobalt(II) tetranitrate complexes (A) 2[Co(NO 3) 4] with different countercations, Ph 4P + (1), MePh 3P + (2), and Ph 4As + (3), using X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. Furthermore, the X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1–3 corresponds to themore » zero-field splitting (2(D 2 + 3E 2) 1/2) from 22.5(2) cm –1 in 1 to 26.6(3) cm –1 in 2 and 11.1(5) cm –1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm –1 for 1–3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). Finally, the electronic structures and the origin of magnetic anisotropy of 1–3 were revealed by calculations at the CASPT2/NEVPT2 level.« less

Organic nitrates and nitrate resistance in diabetes: the role of vascular dysfunction and oxidative stress with emphasis on antioxidant properties of pentaerithrityl tetranitrate.

PubMed

Oelze, Matthias; Schuhmacher, Swenja; Daiber, Andreas

2010-01-01

Organic nitrates represent a class of drugs which are clinically used for treatment of ischemic symptoms of angina as well as for congestive heart failure based on the idea to overcome the impaired NO bioavailability by "NO" replacement therapy. The present paper is focused on parallels between diabetes mellitus and nitrate tolerance, and aims to discuss the mechanisms underlying nitrate resistance in the setting of diabetes. Since oxidative stress was identified as an important factor in the development of tolerance to organic nitrates, but also represents a hallmark of diabetic complications, this may represent a common principle for both disorders where therapeutic intervention should start. This paper examines the evidence supporting the hypothesis that pentaerithrityl tetranitrate may represent a nitrate for treatment of ischemia in diabetic patients. This evidence is based on the considerations of parallels between diabetes mellitus and nitrate tolerance as well as on preliminary data from experimental diabetes studies.

Organic Nitrates and Nitrate Resistance in Diabetes: The Role of Vascular Dysfunction and Oxidative Stress with Emphasis on Antioxidant Properties of Pentaerithrityl Tetranitrate

PubMed Central

Oelze, Matthias; Schuhmacher, Swenja; Daiber, Andreas

2010-01-01

Organic nitrates represent a class of drugs which are clinically used for treatment of ischemic symptoms of angina as well as for congestive heart failure based on the idea to overcome the impaired NO bioavailability by “NO” replacement therapy. The present paper is focused on parallels between diabetes mellitus and nitrate tolerance, and aims to discuss the mechanisms underlying nitrate resistance in the setting of diabetes. Since oxidative stress was identified as an important factor in the development of tolerance to organic nitrates, but also represents a hallmark of diabetic complications, this may represent a common principle for both disorders where therapeutic intervention should start. This paper examines the evidence supporting the hypothesis that pentaerithrityl tetranitrate may represent a nitrate for treatment of ischemia in diabetic patients. This evidence is based on the considerations of parallels between diabetes mellitus and nitrate tolerance as well as on preliminary data from experimental diabetes studies. PMID:21234399

Growth and defects of explosives crystals

NASA Astrophysics Data System (ADS)

Cady, H. H.

Large single crystals of PETN, RDX, and TNT can be grown easily from evaporating ethyl acetate solutions. The crystals all share a similar type of defect that may not be commonly recognized. The defect generates conical faces, ideally mosaic crystals, and may account for the 'polymorphs' of TNT and detonator grades of PETN. TATB crystals manufactured by the amination of trichlorotrinitrobenzene in dry toluene entrain two forms of ammonium chloride. One of these forms causes 'worm holes' in the TATB crystals that may be the reason for its unusually low failure diameters. Strained HMX crystals form mechanical twins that can spontaneously revert back to the untwinned form when the straining force is removed. Large strains or temperatures above 100 C lock in the mechanical twins.

First-principles studies of PETN molecular crystal vibrational frequencies under high pressure

NASA Astrophysics Data System (ADS)

Perger, Warren; Zhao, Jijun

2005-07-01

The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The pressure-induced shift of the vibrational frequencies will be presented and compared with experiment. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used.

Determination of enthalpies of formation of energetic molecules with composite quantum chemical methods

DOE PAGES

Manaa, M. Riad; Fried, Laurence E.; Kuo, I-Feng W.

2016-02-01

We report gas-phase enthalpies of formation for the set of energetic molecules NTO, DADE, LLM-105, TNT, RDX, TATB, HMX, and PETN using the G2, G3, G4, and ccCA-PS3 quantum composite methods. Calculations for HMX and PETN hitherto represent the largest molecules attempted with these methods. G3 and G4 calculations are typically close to one another, with a larger difference found between these methods and ccCA-PS3. Furthermore there is significant uncertainty in experimental values, the mean absolute deviation between the average experimental value and calculations are 12, 6, 7, and 3 kcal/mol for G2, G3, G4, and ccCA-PS3, respectively.

Negative-ion formation in the explosives RDX, PETN, and TNT by using the reversal electron attachment detection technique

NASA Technical Reports Server (NTRS)

Boumsellek, S.; Alajajian, S. H.; Chutjian, A.

1992-01-01

First results of a beam-beam, single-collision study of negative-ion mass spectra produced by attachment of zero-energy electrons to the molecules of the explosives RDX, PETN, and TNT are presented. The technique used is reversal electron attachment detection (READ) wherein the zero-energy electrons are produced by focusing an intense electron beam into a shaped electrostatic field which reverses the trajectory of electrons. The target beam is introduced at the reversal point, and attachment occurs because the electrons have essentially zero longitudinal and radial velocity. The READ technique is used to obtain the 'signature' of molecular ion formation and/or fragmentation for each explosive. Present data are compared with results from atmospheric-pressure ionization and negative-ion chemical ionization methods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of PETN Class 4. The PETN was found to have: 1) an impact sensitivity (DH 50) range of 6 to 12 cm, 2) a BAM friction sensitivity (F 50) range 7 to 11 kg, TIL (0/10) of 3.7 to 7.2 kg, 3) a ABL friction sensitivity threshold of 5 or less psig at 8 fps, 4) an ABL ESD sensitivity thresholdmore » of 0.031 to 0.326 j/g, and 5) a thermal sensitivity of an endothermic feature with T min = ~ 141 °C, and a exothermic feature with a T max = ~205°C.« less

Vascular graft infections: in vitro and in vivo investigations of a new vascular graft with long-term protection.

PubMed

Ueberrueck, Torsten; Zippel, Roland; Tautenhahn, Joerg; Gastinger, Ingo; Lippert, Hans; Wahlers, Thorsten

2005-07-01

We investigated a polyester vascular prosthesis (PET) coated with elemental silver (SC). Measurement of silver release over a period of 52 weeks by means of inductively coupled plasma atomic emission spectrometry of PET with (PET-G) and without (PET-N) gelatine impregnation revealed a silver release on the first day of 1.2 +/- 0.2 microg (PET-N) and 1.2 +/- 0.1 microg (PET-G) (calculated for 1 g of prosthesis); from the 90th day onward, it was between 0.22 +/- 0.14 microg (PET-N) and 0.18 +/- 0.12 microg (PET-G) per day. The prostheses were incubated with Staphylococcus aureus (S.a.), Staphylococcus epidermidis (S.e.), or Escherichia coli (E.c.) to investigate in vitro antibacterial efficacy. After 6 h of incubation, no colony-forming units were to be seen for any of the bacterial suspensions for PET with SC (p < 0.001). To investigate in vivo antibacterial efficacy, PET-G rings with and without SC contaminated with S.a., S.e., or E.c. were implanted in 18 albino rabbits and examined 7 days after agar culture for 48 h. The silver coating was associated with a significant reduction in bacterial growth (S.a., p = 0.001; S.e., p < 0.005; E.c., p < 0.001). The silver-coated prosthesis, with and without gelatine impregnation, had a significantly antibacterial effect with continuous release of silver. Copyright 2005 Wiley Periodicals, Inc.

Synthesis and Characterization of Tetranitraminocyclobutanes

DTIC Science & Technology

1994-09-01

potassium cyanate in aqueous HCl yields urea acetal, 5, a white crystalline solid, which is dehydratively ring closed to imidazolidinone 6 in mild acid...dimerization produces exclusively the cis-trans-cis tetramine isomer as shown. Hydrolysis of the acetate groups is carried out in refluxing ethanol...there is some hydrolysis of the final product. Because nitramine 1 is under consideration as a potential replacement for pentaerythritol tetranitrate

Advancing Explosives Detection Capabilities: Vapor Detection

ScienceCinema

Atkinson, David

2018-05-11

A new, PNNL-developed method provides direct, real-time detection of trace amounts of explosives such as RDX, PETN and C-4. The method selectively ionizes a sample before passing the sample through a mass spectrometer to detect explosive vapors. The method could be used at airports to improve aviation security.

Advancing Explosives Detection Capabilities: Vapor Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, David

2012-10-15

A new, PNNL-developed method provides direct, real-time detection of trace amounts of explosives such as RDX, PETN and C-4. The method selectively ionizes a sample before passing the sample through a mass spectrometer to detect explosive vapors. The method could be used at airports to improve aviation security.

Deformation and Thermal Properties of Energetic Materials.

DTIC Science & Technology

1980-12-01

have done some experiments in which they find that tetramethylammonium tribo- hydride (a free radical donor) causes increased reaction with ammonium ... nitrate . In order to test this hypothesis, mixtures of benzoyl peroxide and PETN were used in a series of TG experiments. Benzoyl peroxide is an...thec Lui~ycr;1 i that ;1 pol1 m\

Dry immunochemical sensor for the detection of PETN vapor

NASA Astrophysics Data System (ADS)

Lukens, Herbert Richard

1992-05-01

Giaever (1973) showed that an indium semi-mirror coated with a monolayer of a substance would undergo reduced optical reflectance after incubation with a solution of the substance's antibody. He was able to see the effect with the naked eye. Lukens and Williams (1977) reversed the process by first attaching the target substance's antibody to the semi-mirror, after which the device would show a decline in optical density when exposed to a solution of the target substance. Lukens and Williams (1982) subsequently found that the device could also be used as an immunochemical film badge (IFB) to detect an airborne target substance. Early efforts to develop the IFB for the detection of airborne substances were plagued by such a high degree of performance variability that there were doubts in some quarters that an airborne target substance could bind to its antibody until Lukens (1990) demonstrated such binding in experiments with radiolabeled cocaine and morphine. Recently improved semi-mirrors and densitometry have been obtained and have led to improved performance of IFB's. As shown in this paper, IFB's can now be constructed that detect PETN vapor in a few seconds.

Thermal properties and chemical reactivity. Quarterly report, October 1971--December 1971

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, L.C.

1998-12-31

A very high boiling impurity was concentrated from a sample of FEFO with a hexane wash. Additional washing of this sample has increased the concentration of this impurity. A mass spectrum was obtained but an identification has not been made. The results of the analysis of the products from the thermal decomposition of FEFO at 120, 135, 150 C are discussed. A chromatogram of FEFO heated for 22 hours at 150 C shows a definite increase in low and high boiling impurities. The evaluation of the condition of the two coupon test assemblies aged at 80 C for 21 andmore » 27 months are discussed. Thermal analysis of the LX-09 from these two coupon tests, a PASS A mechanical test specimen and a control sample are reported. A PDP-12/30 was interfaced with a Perkin Elmer DSC-1 to measure the heat of fusion of PETN. Some of the problems associated with getting reproducible data are discussed. The heat of fusion for six lots of LX-13 grade PETN are given.« less

The Low-Temperature Vibrational Behavior of Pentaerythritol Tetranitrate

DTIC Science & Technology

2008-06-01

light is extracted from the vacuum ultraviolet storage ring in a 40- × 40-mrad solid angle. The collimated beam is delivered through a vacuum pipe ...a role in the stabilization of the D2 conformer. It is suspect that the presence of the shear planes stabilizes the D2 conformer at such extreme...findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents

Genetic and Structural Characterization of L11 Lipooligosaccharide from Neisseria meningitidis Serogroup A Strains

PubMed Central

Mistretta, Noëlle; Seguin, Delphine; Thiébaud, Jerôme; Vialle, Sandrine; Blanc, Frédéric; Brossaud, Marina; Talaga, Philippe; Norheim, Gunnstein; Moreau, Monique; Rokbi, Bachra

2010-01-01

The lipooligosaccharide (LOS) of immunotype L11 is unique within serogroup A meningococci. In order to resolve its molecular structure, we conducted LOS genotyping by PCR analysis of genes responsible for α-chain sugar addition (lgtA, -B, -C, -E, -H, and -F) and inner core substituents (lgtG, lpt-3, and lpt-6). For this study, we selected seven strains belonging to subgroup III, a major clonal complex responsible for meningococcal meningitis epidemics in Africa. In addition, we sequenced the homopolymeric tract regions of three phase-variable genes (lgtA, lgtG, and lot-3) to predict gene functionality. The fine structure of the L11 LOS of each strain was determined using composition and glycosyl linkage analyses, NMR, and mass spectrometry. The masses of the dephosphorylated oligosaccharides were consistent with an oligosaccharide composed of two hexoses, one N-acetyl-hexosamine, two heptoses, and one KDO, as proposed previously. The molar composition of LOS showed two glucose residues to be present, in agreement with lgtH sequence prediction. Despite phosphoethanolaminetransferase genes lpt-3 and lpt-6 being present in all seven Neisseria meningitidis strains, phosphoethanolamine (PEtn) was found at both O-3 and O-6 of HepII among the three ST-5 strains, whereas among the four ST-7 strains, only one PEtn was found and located at O-3 of the HepII. The L11 LOS was found to be O-acetylated, as was indicated by the presence of the lot-3 gene being in-frame in all of the seven N. meningitidis strains. To our knowledge, these studies represent the first full genetic and structural characterization of the L11 LOS of N. meningitidis. These investigations also suggest the presence of further regulatory mechanisms affecting LOS structure microheterogeneity in N. meningitidis related to PEtn decoration of the inner core. PMID:20421293

Integrated Data Collection Analysis (IDCA) program--KClO 4/Dodecane Mixture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of a mixture of KClO 4 and dodecane—KClO 4/dodecane mixture. This material was selected because of the challenge of performing SSST testing of a mixture of solid and liquid materials. The mixture was found to: 1) be less sensitive to impact than RDX, and PETN, 2) less sensitive to friction than RDX and PETN, and 3) less sensitive to spark thanmore » RDX and PETN. The thermal analysis showed little or no exothermic features suggesting that the dodecane volatilized at low temperatures. A prominent endothermic feature was observed and assigned to a phase transition of KClO 4. This effort, funded by the Department of Homeland Security (DHS), ultimately will put the issues of safe handling of these materials in perspective with standard military explosives. The study is adding SSST testing results for a broad suite of different HMEs to the literature. Ultimately the study has the potential to suggest new guidelines and methods and possibly establish the SSST testing accuracies needed to develop safe handling practices for HMEs. Each participating testing laboratory uses identical test materials and preparation methods wherever possible. Note, however, the test procedures differ among the laboratories. The results are compared among the laboratories and then compared to historical data from various sources. The testing performers involved for the KClO 4/dodecane mixture are Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Indian Head Division, Naval Surface Warfare Center, (NSWC IHD), and Air Force Research Laboratory (AFRL/RXQL). These tests are conducted as a proficiency study in order to establish some consistency in test protocols, procedures, and experiments and to understand how to compare results when these testing variables cannot be made consistent.« less

Organic Explosives and Related Compounds. Environmental and Health Considerations

DTIC Science & Technology

1989-03-01

compounds used as explosives and in propellant formulations. While a summiary of synthetic processes is included, emphasis is focused on behavior and...INTRODUCTION .......................................................... 3 SYNTHESIS/ PRODUCTION AND USE .......................................... 5...2 , NG PA DEGDN C(CH2 ON02)4 PETN Figure 1. Structures of Explosives and Related Compounds SYNTHESIS/ PRODUCTION AND USE Methods for the synthesis or

Insensitive High Energy Propellants for Advanced Gun Concepts

DTIC Science & Technology

2001-10-01

tetranitrate pentaerythritol), RDX , HMX , r3- and 6- polymorphs of CL20, HNS (2,2’,4,4’,6,6’-hexanitrostilbene), methyl picrate, styphnic acid, NTO (3...cyclic nitramines RDX (hexahydro-l,3,5-trinitro-l,3,5-7-triazine) and HMX (1,3,5,7-tetranitro-l,3,5,7- tetraazacyclooctane) to address these goals...inclusion of energetic fillers, such as RDX and 3 CL20, while maintaining good physical properties and providing the option for reprocessing. TPEs

Detection of microscopic particles present as contaminants in latent fingerprints by means of synchrotron radiation-based Fourier transform infra-red micro-imaging.

PubMed

Banas, A; Banas, K; Breese, M B H; Loke, J; Heng Teo, B; Lim, S K

2012-08-07

Synchrotron radiation-based Fourier transform infra-red (SR-FTIR) micro-imaging has been developed as a rapid, direct and non-destructive technique. This method, taking advantage of the high brightness and small effective source size of synchrotron light, is capable of exploring the molecular chemistry within the microstructures of microscopic particles without their destruction at high spatial resolutions. This is in contrast to traditional "wet" chemical methods, which, during processing for analysis, often caused destruction of the original samples. In the present study, we demonstrate the potential of SR-FTIR micro-imaging as an effective way to accurately identify microscopic particles deposited within latent fingerprints. These particles are present from residual amounts of materials left on a person's fingers after handling such materials. Fingerprints contaminated with various types of powders, creams, medications and high explosive materials (3-nitrooxy-2,2-bis(nitrooxymethyl)propyl nitrate (PETN), 1,3,5-trinitro-1,3,5-triazinane (RDX), 2-methyl-1,3,5-trinitrobenzene (TNT)) deposited on various - daily used - substrates have been analysed herein without any further sample preparation. A non-destructive method for the transfer of contaminated fingerprints from hard-to-reach areas of the substrates to the place of analysis is also presented. This method could have a significant impact on forensic science and could dramatically enhance the amount of information that can be obtained from the study of fingerprints.

Environmental Acceptable Medium Caliber Ammunition Percussion Primers

DTIC Science & Technology

2008-05-01

the nanoparticles extremely hydrophobic. The alternative treatment of the solution was the addition of ammonium dihydrogen phosphate (ADP) to serve as...Ultrafine Aluminum Nanoparticles," LA-UR-04-2921. 49 ACRONYM LIST ADP Ammonium Dihydrogen Phosphate Al Aluminum ARDEC Armament Research Development and...Nitrocellulose Nd:Yag Neodymium -doped yttrium aluminum garnet NSWC-IH Naval Surface Warfare Center- Indian Head PAD Propellant actuated device PETN

The Complete Plastome Sequence of an Antarctic Bryophyte Sanionia uncinata (Hedw.) Loeske

PubMed Central

Park, Mira; Park, Hyun; Lee, Hyoungseok; Lee, Byeong-ha

2018-01-01

Organellar genomes of bryophytes are poorly represented with chloroplast genomes of only four mosses, four liverworts and two hornworts having been sequenced and annotated. Moreover, while Antarctic vegetation is dominated by the bryophytes, there are few reports on the plastid genomes for the Antarctic bryophytes. Sanionia uncinata (Hedw.) Loeske is one of the most dominant moss species in the maritime Antarctic. It has been researched as an important marker for ecological studies and as an extremophile plant for studies on stress tolerance. Here, we report the complete plastome sequence of S. uncinata, which can be exploited in comparative studies to identify the lineage-specific divergence across different species. The complete plastome of S. uncinata is 124,374 bp in length with a typical quadripartite structure of 114 unique genes including 82 unique protein-coding genes, 37 tRNA genes and four rRNA genes. However, two genes encoding the α subunit of RNA polymerase (rpoA) and encoding the cytochrome b6/f complex subunit VIII (petN) were absent. We could identify nuclear genes homologous to those genes, which suggests that rpoA and petN might have been relocated from the chloroplast genome to the nuclear genome. PMID:29494552

Equation of State for Detonation Product Gases

NASA Astrophysics Data System (ADS)

Nagayama, Kunihito; Kubota, Shiro

2013-06-01

Based on the empirical linear relationship between detonation velocity and loading density, an approximate description for the Chapman-Jouguet state for detonation product gases of solid phase high explosives has been developed. Provided that the Grüneisen parameter is a function only of volume, systematic and closed system of equations for the Grüneisen parameter and CJ volume have been formulated. These equations were obtained by combining this approximation with the Jones-Stanyukovich-Manson relation together with JWL isentrope for detonation of crystal density PETN. A thermodynamic identity between the Grüneisen parameter and another non-dimensional material parameter introduced by Wu and Jing can be used to derive the enthalpy-pressure-volume equation of state for detonation gases. This Wu-Jing parameter is found to be the ratio of the Grüneisen parameter and the adiabatic index. Behavior of this parameter as a function of pressure was calculated and revealed that their change with pressure is very gradual. By using this equation of state, several isentropes down from the Chapman-Jouguet states reached by four different lower initial density PETN have been calculated and compared with available cylinder expansion tests.

Electric conductivity of high explosives with carbon nanotubes

NASA Astrophysics Data System (ADS)

Rubtsov, I. A.; Pruuel, E. R.; Ten, K. A.; Kashkarov, A. O.; Kremenko, S. I.

2017-09-01

The paper presents a technique for introducing carbon nanotubes into high explosives (HEs). For a number of explosives (trinitrotoluene, pentaerythritol tetranitrate, benzotrifuroxan), it was possible to achieve the appearance of conductivity by adding a small amount (up to 1% by mass) of single-walled carbon nanotubes TUBALL COATE H2O (CNTs) produced by OCSiAl. Thus it is possible to reduce the sensitivity of explosives to static electricity by adding an insignificant part of conductive nanotubes. This will increase safety of HEs during production and application and will reduce the number of accidents.

Spectral-kinetic characteristics of luminescence of pentaerythritol tetranitrate with inclusions of iron nanoparticles upon explosion induced by laser pulses

NASA Astrophysics Data System (ADS)

Aduev, B. P.; Nurmukhametov, D. R.; Belokurov, G. M.; Nelyubina, N. V.; Gudilin, A. V.

2017-03-01

Spectral-kinetic characteristics of luminescence of tetranitropentaeritrite with inclusions of iron nanoparticles upon an explosion induced by laser pulses are measured with high temporal resolution. It is shown that the luminescence occurring during exposure to the laser pulse is a result of initiating a chemical reaction in tetranitropentaeritrite and is chemiluminescence. The glow is presumably associated with the excited nitrogen dioxide, NO2, which is formed by the rupture of O-NO2 bond in the tetranitropentaeritrite molecule.

Acoustic Identification of Filler Materials in Unexploded Ordnance

DTIC Science & Technology

2006-04-01

PBXN- 103 CH-6 PBXW- 108 Parrafin ( wax ) Baratol (76/24) Plaster TNT Octol (50/50) Comp B PETN Concrete Lo ng itu di na l V el oc ity (m /s ec...26 3.7.3 Identification of Wax fillers...plaster and wax from “other” items including explosives. A series of field tests are described that focus on acoustic measurements on both inert and live

Spectral Characterization of RDX, ETN, PETN, TATP, HMTD, HMX, and C-4 in the Mid-Infrared Region

DTIC Science & Technology

2014-04-01

Samuels Joseph A. Domanico Joseph May Ronald W. Miles, Jr. Augustus W. Fountain III RESEARCH AND TECHNOLOGY DIRECTORATE April 2014 Approved for public ...position unless so designated by other authorizing documents. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting...AVAILABILITY STATEMENT Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES *Science Applications International Corporation

Short-term administration of uridine increases brain membrane phospholipids precursors in healthy adults: a 31-phosphorus magnetic resonance spectroscopy study at 4T

PubMed Central

Agarwal, Nivedita; Sung, Young-Hoon; Jensen, J Eric; daCunha, Grace; Harper, David; Olson, David; Renshaw, Perry F

2010-01-01

Objectives Altered metabolism of membrane phospholipids has been implicated in bipolar disorder. In humans, uridine is an important precursor of cytidine diphosphate (CDP)-choline, which plays a critical role in phospholipid synthesis and is currently being evaluated as a potential treatment for bipolar depression. Methods A total of 17 healthy males (mean age ± SD: 32.73 ± 7.2 years; range: 21.8- 46.4 years) were enrolled in this study. Subjects underwent a 31-phosphorus magnetic resonance spectroscopy (31P-MRS) acquisition at baseline and then again after seven days of either 2 g of uridine or placebo administration. A two-dimensional chemical shift imaging 31P-MRS acquisition collected spectral data from a 4 × 4 cluster of voxels acquired in the axial plane encompassing the subcortical structures as well as frontaltemporal cortical gray and white matter. The slab thickness was 3 cm and the approximate total volume of brain sampled was 432 cm3. The spectra obtained were analyzed using a fully automated in-house fitting algorithm. A population-averaged generalized estimating equation was used to evaluate changes both in phosphomonoesters (PME) [phosphocholine (PCho) and phosphoethanolamine (PEtn)] and phosphodiesters (PDE) [glycerophosphocholine (GPCho) and glycerophosphethanolamine (GPEtn)]. Metabolite ratios were reported with respect to the total integrated 31P resonance area. Results The uridine group had significantly increased total PME and PEtn levels over the one-week period [6.32% and 7.17% for PME and PEtn, respectively (p < 0.001)]. Other metabolite levels such as PCho, PDE, GPEtn and GPCho showed no significant changes following either uridine or placebo (all p > 0.05). Conclusions This is the first study to report a direct effect of uridine on membrane phospholipid precursors in healthy adults using 31P-MRS. Sustained administration of uridine appears to increase PME in healthy subjects. Further investigation is required to clarify the effects of uridine in disorders with altered phospholipid metabolism such as bipolar disorder. PMID:21176029

Role of Thermochemical Decomposition in Energetic Material Initiation Sensitivity and Explosive Performance

DTIC Science & Technology

2007-02-05

Electronic excitation has been suggested as one contributing mechanistic step in a multiprocess detonation model [18], and such electronic...and, (b) Dick, J. J., Orientation Dependence of the Shock Initiation Sensitivity of PETN: A Steric Hindrance Model , Workshop on Desensitization of...Explosives and Propellants, Rijswijk, The Netherlands, 11-13 Nov 1991. [15] Piermarini, G. J., Block, S., Miller , P. J., Effects of Pressure on

Synthesis and Characterization of Mono-, Di-, and Tetranitrated 7,8-Disubstituted Glycolurils

DTIC Science & Technology

2014-02-01

Cheetah 7.0 [7] . All of the compounds 8–13 are predicted to have performance values less than TNT with 15 and 16 approaching the performance of TNT...0.25 1.25 0.25 a) Calculated values in brackets. b) Calculated using Cheetah 7.0. c) Peak decomposition temperature at 10 Kmin1 in a pinhole pan. d) Ex...118, 445–458. [7] S. Bastea, L. E. Fried, K. R. Glaesemann, W. M. Howard, I. W. Kuo, P. C. Souers, P. A. Vitello, Cheetah 7.0 User’s Manual, LLNL-SM

Detonating apparatus

DOEpatents

Johnston, Lawrence H.

1976-01-01

1. Apparatus for detonation of high explosive in uniform timing comprising in combination, an outer case, spark gap electrodes insulatedly supported in spaced relationship within said case to form a spark gap, high explosive of the class consisting of pentaerythritol tetranitrate and trimethylene trinitramine substantially free from material sensitive to detonation by impact compressed in surrounding relation to said electrodes including said spark gap under a pressure from about 100 psi to about 500 psi, said spark gap with said compressed explosive therein requiring at least 1000 volts for sparking, and means for impressing at least 1000 volts on said spark gap.

Quantum Mechanical Predictions Of Energetic Materials: When Good Theories Go Bad

DTIC Science & Technology

2008-12-01

pressures. The systems studied were nitromethane, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane ( HMX ), cyclotrimethylenetrinitramine ( RDX ...degrees of compression. The systems are RDX , HMX , CL-20, nitromethane, PETN, and TATB. The GGA DFT Perdew-Burke-Ernzerhof (PBE) [Perdew et al., 1996...nitromethane, HMX , RDX and CL-20). At higher degrees of compression, planewave kinetic energy cut- offs (Ecut) were restricted to either 396 eV and/or

Ultraviolet Resonance Raman Enhancements in the Detection of Explosives

DTIC Science & Technology

2009-06-01

nitramines (e.g., RDX , HMX ) and aromatic compounds (e.g., DNT, TATB, TNT). 1. Types of Explosives and Chemical Composition Due to stability...resonance Raman spectra of TNT, RDX , HMX , and PETN using 40 UV wavelengths from 210 to 280 nm using a 90 collection geometry [32]. This study includes...Raman can result in a dramatic increase in the Raman scattering efficiency of select band(s) associated with the electronic transition . Other than

Characterisation of 2,4-Dinitroanisole: An Ingredient for Use in Low Sensitivity Melt Cast Formulations

DTIC Science & Technology

2006-08-01

PETN/TNT 50/50 PMMA Polymethyl methacrylate RDX Cyclotrimethylenetrinitramine RS-RDX Reduced Sensitivity RDX SEM Scanning electron... toxicological data was available on DNAN. It had been proposed that due to the increased solubility of DNAN over TNT in aqueous solution at biologically...While the toxicological study [18], concluded that the vapour pressure of DNAN was not sufficient to cause concerns over inhalation of DNAN during

Understanding the hydrogen transfer mechanism for the biodegradation of 2,4,6-trinitrotoluene catalyzed by pentaerythritol tetranitrate reductase: molecular dynamics simulations.

PubMed

Yang, Zhilin; Chen, Junxian; Zhou, Yang; Huang, Hui; Xu, Dingguo; Zhang, Chaoyang

2018-05-03

The explosive 2,4,6-trinitrotoluene (TNT) is a highly toxic pollutant. Biodegradation is inevitably one of the most cost-effective and enviromentally friendly means of removing TNT pollution. However, the aromatic derivatives from the reduction of nitro groups by several classic enzymes are still toxic. Besides the reduction of nitro groups, pentaerythritol tetranitrate reductase (PETNR) offers a potential route to ring fission and complete degradation of TNT through the pathway of the Meisenheimer complex. This work is devoted to deeply understand the essence of the Meisenheimer pathway and mainly focus on the crucial hydrogen-transfer reaction by means of molecular dynamics (MD) simulations. We obtain three valuable findings. Firstly, the parallel π-π stacking between TNT and the flavin mononucleotide (FMN) cofactor is a precondition. The key residue controlling this conformation is His181. Although His184 does not interact with TNT, the mutation from His184 to Asn184 would abolish the π-π structure. Secondly, the data of the empirical valence bond (EVB) show that the Meisenheimer pathway is predominant because its activation barrier is 6.7 kcal mol-1 far less than that of nitro reduction (26.6 kcal mol-1). Finally, based on the results of thermodynamic integration (TI), the type of transferred hydrogen is also ensured, that is, the H anion (H-) for the Meisenheimer complex and the H radical (H˙) for nitro reduction. Our findings provide an exhaustive understanding for the first hydrogen transfer reaction that has a decisive effect on two competing pathways, and help in searching for and designing new enzymes that can effectively degrade TNT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martz, Joseph Christopher; Spearing, Dane Robert; Labouriau, Andrea

Microclad is a composite material consisting of a thin copper coating applied on a single side over a Kapton substrate. Kapton is the commercial designator for polyimide supplied by DuPont. Microclad is a key material in detonator manufacture and function. Detonators which utilize Microclad function when a large current applied through a thin bridge etched into the copper produces a plasma, accelerating a Kapton flyer into an explosive (PETN) pellet. The geometry and properties of the Microclad are a critical element of this process.

A Computational Examination of Detonation Physics and Blast Chemistry

DTIC Science & Technology

2011-08-01

State 5 3 Detonation and Shock Hugoniots for TNT using the JWL Equation of State 6 4 Detonation and Shock Hugoniots for HMX using the JWL ...Equation of State 6 5 Detonation and Shock Hugoniots for Composition C-4 using the JWL Equation of State 7 6 Detonation and Shock...Hugoniots for PBX-9502 using the JWL Equation of State 7 7 Detonation and Shock Hugoniots for PETN using the JWL Equation of State 8 8

A Computational Examination of Detonation Physics and Blast Chemistry

DTIC Science & Technology

2011-08-01

Equation of State 5 3 Detonation and Shock Hugoniots for TNT using the JWL Equation of State 6 4 Detonation and Shock Hugoniots for HMX using the... JWL Equation of State 6 5 Detonation and Shock Hugoniots for Composition C-4 using the JWL Equation of State 7 6 Detonation and...Shock Hugoniots for PBX-9502 using the JWL Equation of State 7 7 Detonation and Shock Hugoniots for PETN using the JWL Equation of State 8

Nonlinear electromagnetic interactions in energetic materials

DOE PAGES

Wood, Mitchell Anthony; Dalvit, Diego Alejandro; Moore, David Steven

2016-01-12

We study the scattering of electromagnetic waves in anisotropic energetic materials. Nonlinear light-matter interactions in molecular crystals result in frequency-conversion and polarization changes. Applied electromagnetic fields of moderate intensity can induce these nonlinear effects without triggering chemical decomposition, offering a mechanism for the nonionizing identification of explosives. We use molecular-dynamics simulations to compute such two-dimensional THz spectra for planar slabs made of pentaerythritol tetranitrate and ammonium nitrate. Finally, we discuss third-harmonic generation and polarization-conversion processes in such materials. These observed far-field spectral features of the reflected or transmitted light may serve as an alternative tool for standoff explosive detection.

Wavelength-Dependence on the Initiation of Iron-Based Photoactive Explosives

NASA Astrophysics Data System (ADS)

Brown, Kathryn; Myers, Thomas; Clarke, Steven

2017-06-01

Photoactive explosives show promise to be relatively insensitive to impact and friction compared to PETN and other detonator materials, but can be more easily initiated with laser light. Metal-ligand charge transfer (MLCT) complexes have been shown to have tunable explosive properties and absorption profiles, making them strong candidates for laser detonator material. Here, we discuss the synthesis and characterization of several iron-based MLCT complexes, as well as results from recent experiments on their sensitivity to initiation from different wavelengths of laser light.

Detection of Threat Materials Using Terahertz Waveguides and Long Pathlength Terahertz Spectroscopy

DTIC Science & Technology

2015-05-01

intramolecular modes. Therefore a complex spectrum is anticipated. In the range between 0.2 THz and 3.0 THz there have been several free space THz...narrowing. A more complex underlying spectrum is only suggested, but not resolved. A PETN layer was formed on an Au-coated PPWG surface by drop casting...structure of the analyte, or complex formation where metal ions incorporate into the lattice of the analyte. In each of these cases the resulting THz

Insensitive fuze train for high explosives

DOEpatents

Cutting, Jack L.; Lee, Ronald S.; Von Holle, William G.

1994-01-01

A generic insensitive fuze train to initiate insensitive high explosives, such as PBXW-124. The insensitive fuze train uses a slapper foil to initiate sub-gram quantities of an explosive, such as HNS-IV or PETN. This small amount of explosive drives a larger metal slapper onto a booster charge of an insensitive explosive, such as UF-TATB. The booster charge initiates a larger charge of an explosive, such as LX-17, which in turn, initiates the insensitive high explosive, such as PBXW-124.

Correlating cookoff violence with pre-ignition damage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wente, William Baker; Hobbs, Michael L.; Kaneshige, Michael Jiro

Predicting the response of energetic materials during accidents, such as fire, is important for high consequence safety analysis. We hypothesize that responses of ener-getic materials before and after ignition depend on factors that cause thermal and chemi-cal damage. We have previously correlated violence from PETN to the extent of decom-position at ignition, determined as the time when the maximum Damkoehler number ex-ceeds a threshold value. We seek to understand if our method of violence correlation ap-plies universally to other explosive starting with RDX.

Insensitive fuze train for high explosives

DOEpatents

Cutting, J.L.; Lee, R.S.; Von Holle, W.G.

1994-01-04

A generic insensitive fuze train to initiate insensitive high explosives, such as PBXW-124 is described. The insensitive fuze train uses a slapper foil to initiate sub-gram quantities of an explosive, such as HNS-IV or PETN. This small amount of explosive drives a larger metal slapper onto a booster charge of an insensitive explosive, such as UF-TATB. The booster charge initiates a larger charge of an explosive, such as LX-17, which in turn, initiates the insensitive high explosive, such as PBXW-124. 3 figures.

Laser-Based Remote Sensing of Explosives by a Differential Absorption and Scattering Method

NASA Astrophysics Data System (ADS)

Ayrapetyan, V. S.

2018-01-01

A multifunctional IR parametric laser system is developed and tested for remote detection and identification of atmospheric gases, including explosive and chemically aggressive substances. Calculations and experimental studies of remote determination of the spectroscopic parameters of the best known explosive substances TNT, RDX, and PETN are carried out. The feasibility of high sensitivity detection ( 1 ppm) of these substances with the aid of a multifunctional IR parametric light source by differential absorption and scattering is demonstrated.

Low-mass ions observed in plasma desorption mass spectrometry of high explosives

PubMed

Hakansson; Coorey; Zubarev; Talrose; Hakansson

2000-03-01

The low-mass ions observed in both positive and negative plasma desorption mass spectrometry (PDMS) of the high explosives HMX, RDX, CL-20, NC, PETN and TNT are reported. Possible identities of the most abundant ions are suggested and their presence or absence in the different spectra is related to the properties of the explosives as matrices in PDMS. The detection of abundant NO+ and NO2- ions for HMX, RDX and CL-20, which are efficient matrices, indicates that explosive decomposition takes place in PDMS of these three substances and that a contribution from the corresponding chemical energy release is possible. The observation of abundant C2H4N+ and CH2N+ ions, which have high protonation properties, might also explain the higher protein charge states observed with these matrices. Also, the observation of NO2-, possibly formed by electron scavenging which increases the survival probability of positively charged protein molecular ions, completes the pattern. TNT does not give any of these ions and it is thereby possible to explain why it does not work as a PDMS matrix. For NC and PETN, decomposition does not seem to be as pronounced as for HMX, RDX and CL-20, and also no particularly abundant ions with high protonation properties are observed. The fact that NC works well as a matrix might be related to other properties of this compound, such as its high adsorption ability.

Proximal Detection of Traces of Energetic Materials with an Eye-Safe UV Raman Prototype Developed for Civil Applications

PubMed Central

Chirico, Roberto; Almaviva, Salvatore; Colao, Francesco; Fiorani, Luca; Nuvoli, Marcello; Schweikert, Wenka; Schnürer, Frank; Cassioli, Luigi; Grossi, Silvana; Murra, Daniele; Menicucci, Ivano; Angelini, Federico; Palucci, Antonio

2015-01-01

A new Raman-based apparatus for proximal detection of energetic materials on people, was developed and tested for the first time. All the optical and optoelectronics components of the apparatus, as well as their optical matching, were carefully chosen and designed to respect international eye-safety regulations. In this way, the apparatus is suitable for civil applications on people in public areas such as airports and metro or railway stations. The acquisition software performs the data analysis in real-time to provide a fast response to the operator. Moreover, it allows for deployment of the apparatus either as a stand alone device or as part of a more sophisticated warning system architecture made up of several sensors. Using polyamide as substrate, the apparatus was able to detect surface densities of ammonium nitrate (AN), 2-methyl-1,3,5-trinitrobenzene (TNT), 3-nitrooxy-2,2-bis(nitrooxymethyl)propyl] nitrate (PETN) and urea nitrate (UN) in the range of 100–1000 μg/cm2 at a distance of 6.4 m using each time a single laser pulse of 3 mJ/cm2. The limit of detection calculated for AN is 289 μg/cm2. AN and UN provided the highest percentages of true positives (>82% for surface densities of 100–400 μg/cm2 and fingerprints) followed by TNT and PETN (17%–70% for surface densities of 400–1000 μg/cm2 and fingerprints). PMID:26703613

Fabrication of a self-assembled and flexible SERS nanosensor for explosive detection at parts-per-quadrillion levels from fingerprints.

PubMed

Liyanage, Thakshila; Rael, Ashur; Shaffer, Sidney; Zaidi, Shozaf; Goodpaster, John V; Sardar, Rajesh

2018-04-30

Apart from high sensitivity and selectivity of surface-enhanced Raman scattering (SERS)-based trace explosive detection, efficient sampling of explosive residue from real world surfaces is very important for homeland security applications. Herein, we demonstrate an entirely new SERS nanosensor fabrication approach. The SERS nanosensor was prepared by self-assembling chemically synthesized gold triangular nanoprisms (Au TNPs), which we show display strong electromagnetic field enhancements at the sharp tips and edges, onto a pressure-sensitive flexible adhesive film. Our SERS nanosensor provides excellent SERS activity (enhancement factor = ∼6.0 × 106) and limit of detection (as low as 56 parts-per-quadrillions) with high selectivity by chemometric analyses among three commonly military high explosives (TNT, RDX, and PETN). Furthermore, the SERS nanosensors present excellent reproducibility (<4.0% relative standard deviation at 1.0 μM concentration) and unprecedentedly high stability with a "shelf life" of at least 5 months. Finally, TNT and PETN were analyzed and quantified by transferring solid explosive residues from fingerprints left on solid surfaces to the SERS nanosensor. Taken together, the demonstrated sensitivity, selectivity, and reliability of the measurements as well as with the excellent shelf life of our SERS nanosensors obviate the need for complicated sample processing steps required for other analytical techniques, and thus these nanosensors have tremendous potential not only in the field of measurement science but also for homeland security applications to combat acts of terror and military threats.

CHNO Energetic Polymer Specific Heat Prediction From The Proposed Nominal/Generic (N/G) CP Concept

DTIC Science & Technology

2007-02-01

HMX can exist in different solid polymorphic forms. At a certain temperature, TT, one form may change to another form if the heat energy of...more than 100 °K for TNT, HNS and HMX and over 200 °K for TETRYL, PETN, and RDX ). So based on the above remarks and similar remarks in References...are very close to (or equal to) the RDX CP values and TNT CP values near absolute zero. In Reference 7, two examples (TNT and HMX ) were selected for

Surface Enhanced Raman Scattering (SERS) Detection of Ammonium Nitrate (AN) Samples Fabricated Using Drop-on-Demand Inkjet Technology on Commercial and Fabricated SERS Substrates

DTIC Science & Technology

2013-04-01

III. Characterization of Polymorphic States in Energetic Samples of 1,3,5-Trinitro-1,3,5- Triazine ( RDX ) Fabricated Using Drop-on-Demand Inkjet...Asher, S. A. Deep-Ultraviolet Resonance Raman Excitation Profiles of NH4NO3, PETN, TNT, HMX , and RDX . Appl. Spec. 2012, 66 (9), 1013–1021. 19. Izake...L. A. The IV-III Polymorphic Phase- transition in Smmonium Nitrate – A Unique Example of Solvent Mediation. J. Phys. D. Apply. Phys. 1991, 24 (2

Recent Developments in the Field of Energetic Ionic Liquids

DTIC Science & Technology

2014-10-07

tetranitroaniline RDX 14,18,19,21 1,3,5-trinitro-1,3,5- triazacyclohexane PETN 14,15,21 [3-nitrooxy-2,2-bis(nitro oxymethyl) propyl ] nitrate CL20 21-25...was then proved to play a vital role since the chloride precursor (2a) was also found to be hypergolic. Therefore, the 45 anion is not solely... Synthesis , 1977, 1, 1. 91 C. D. Hurd, L. F. Audrieth and L. A. Nalefski, Inorganic Syntheses, ed. H. S. Booth, McGraw-Hill Book Company Inc., New York

International Symposium on Analysis and Detection of Explosives (4th) Held in Jerusalem, Israel on September 7 - 10, 1992. Programs and Abstracts

DTIC Science & Technology

1992-09-01

chromatography. * DI EXPLOSIVE ANALYSIS USING CAPILLARY ELECTROPHORESIS Bruce R . McCord., Forensic Science Research Unit, FBI Academy, Quantico, VA...gel and emulsion explosives E. Bender, R . Strobel, and C.R. Midkiff. Ir, Bureau of ATF, Rockville, MD, USA 11.05 D3 The analysis of the explosives of...organic substrates . . - r __ A.D. Wright, K.R. Jennings and R . Peters, University of Warwick, Coventry, U.K. 16:40 F2 GC/MS analysis of PETN and NG

Experimental and theoretical studies of the crystal structures of bis-isoxazole-bis-methylene dinitrate (BIDN) and bis-isoxazole tetramethylene tetranitrate (BITN) by x-ray crystallography and density functional theory

NASA Astrophysics Data System (ADS)

Taylor, Decarlos E.; Sausa, Rosario C.

2018-06-01

The determination of crystal structures plays an important role for model testing and validation, and understanding intra and intermolecular interactions that influence crystal packing. Here, we report the molecular structure of two recently synthesized energetic molecules, 3,3-bis-isoxazole-5,5‧-bis-methylene dinitrate (C8H6N4O8, BIDN) and bis-isoxazole tetramethylene tetranitrate (C10H8N6O14, BITN) determined by single crystal x-ray diffraction and solid state density functional theory (DFT). BIDN is composed of two planar alkyl nitrate groups (r.m.s deviation = 0.0004 (1) Å) bonded to two planar azole rings (r.m.s deviation = 0.001 (1) Å, whereas BITN is composed of four planar alkyl nitrate groups (average r.m.s deviation = 0.002 (1) Å) bonded to two planar azole rings (average r.m.s deviation = 0.002 (1) Å). The theoretical calculations predict very well the planarity of both the alkyl nitrate groups and rings for both compounds. Furthermore, they predict well the bond lengths and angles of both molecules with mean deviation values of 0.018 Å (BIDN) and 0.017 Å (BITN) and 0.481° (BIDN) and 0.747° (BITN). Overall, the DFT determined torsion angles agree well with those determined experimentally for both BIDN (average deviation = 1.139°) and BITN (average deviation = 0.604°). The theoretical cell constant values are in excellent agreement with those determined experimentally for both molecules, with the BIDN a cell value and β angle showing the largest deviation, 2.1% and -1.3%, respectively. Contacts between the atoms N and H dominate the intermolecular interactions of BIDN, whereas contacts involving the atoms O and H dominate the BITN intermolecular interactions. Electrostatic potential calculations at the B3LYP/6-31G* level reveal BIDN exhibits a lower sensitivity to impact compared to BITN.

Conservation and Accessibility of an Inner Core Lipopolysaccharide Epitope of Neisseria meningitidis

PubMed Central

Plested, Joyce S.; Makepeace, Katherine; Jennings, Michael P.; Gidney, Margaret Anne J.; Lacelle, Suzanne; Brisson, J.-R.; Cox, Andrew D.; Martin, Adele; Bird, A. Graham; Tang, Christoph M.; Mackinnon, Fiona M.; Richards, James C.; Moxon, E. Richard

1999-01-01

We investigated the conservation and antibody accessibility of inner core epitopes of Neisseria meningitidis lipopolysaccharide (LPS) because of their potential as vaccine candidates. An immunoglobulin G3 murine monoclonal antibody (MAb), designated MAb B5, was obtained by immunizing mice with a galE mutant of N. meningitidis H44/76 (B.15.P1.7,16 immunotype L3). We have shown that MAb B5 can bind to the core LPS of wild-type encapsulated MC58 (B.15.P1.7,16 immunotype L3) organisms in vitro and ex vivo. An inner core structure recognized by MAb B5 is conserved and accessible in 26 of 34 (76%) of group B and 78 of 112 (70%) of groups A, C, W, X, Y, and Z strains. N. meningitidis strains which possess this epitope are immunotypes in which phosphoethanolamine (PEtn) is linked to the 3-position of the β-chain heptose (HepII) of the inner core. In contrast, N. meningitidis strains lacking reactivity with MAb B5 have an alternative core structure in which PEtn is linked to an exocyclic position (i.e., position 6 or 7) of HepII (immunotypes L2, L4, and L6) or is absent (immunotype L5). We conclude that MAb B5 defines one or more of the major inner core glycoforms of N. meningitidis LPS. These findings support the possibility that immunogens capable of eliciting functional antibodies specific to inner core structures could be the basis of a vaccine against invasive infections caused by N. meningitidis. PMID:10496924

Standoff laser-induced thermal emission of explosives

NASA Astrophysics Data System (ADS)

Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Figueroa-Navedo, Amanda; Hernandez-Rivera, Samuel P.

2013-05-01

A laser mediated methodology for remote thermal excitation of analytes followed by standoff IR detection is proposed. The goal of this study was to determine the feasibility of using laser induced thermal emission (LITE) from vibrationally excited explosives residues deposited on surfaces to detect explosives remotely. Telescope based FT-IR spectral measurements were carried out to examine substrates containing trace amounts of threat compounds used in explosive devices. The highly energetic materials (HEM) used were PETN, TATP, RDX, TNT, DNT and ammonium nitrate with concentrations from 5 to 200 μg/cm2. Target substrates of various thicknesses were remotely heated using a high power CO2 laser, and their mid-infrared (MIR) thermally stimulated emission spectra were recorded. The telescope was configured from reflective optical elements in order to minimize emission losses in the MIR frequencies and to provide optimum overall performance. Spectral replicas were acquired at a distance of 4 m with an FT-IR interferometer at 4 cm- 1 resolution and 10 scans. Laser power was varied from 4-36 W at radiation exposure times of 10, 20, 30 and 60 s. CO2 laser powers were adjusted to improve the detection and identification of the HEM samples. The advantages of increasing the thermal emission were easily observed in the results. Signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration), as well as the laser power and laser exposure time. For samples of RDX and PETN, varying the power and time of induction of the laser, the calculated low limit of detections were 2 and 1 μg/cm2, respectively.

Portable sensors for drug and explosive detection

NASA Astrophysics Data System (ADS)

Leginus, Joseph M.

1994-03-01

Westinghouse Electric is developing portable, hand-held sensors capable of detecting numerous drugs of abuse (cocaine, heroin, amphetamines) and explosives (trinitrotoluene, pentaerythritol tetranitrate, nitroglycerin). The easy-to-use system consists of a reusable electronics module and disposable probes. The sensor illuminates and detects light transmitted through optical cells of the probe during an antibody-based latex agglutination reaction. Each probe contains all the necessary reagents to carry out a test in a single step. The probe has the ability to lift minute quantities of samples from a variety of surfaces and deliver the sample to a reaction region within the device. The sensor yields a qualitative answer in 30 to 45 seconds and is able to detect illicit substances at nanogram levels.

A sensitive, handheld vapor sensor based on microcantilevers

NASA Astrophysics Data System (ADS)

Pinnaduwage, L. A.; Hedden, D. L.; Gehl, A.; Boiadjiev, V. I.; Hawk, J. E.; Farahi, R. H.; Thundat, T.; Houser, E. J.; Stepnowski, S.; McGill, R. A.; Deel, L.; Lareau, R. T.

2004-11-01

We report the development of a handheld sensor based on piezoresistive microcantilevers that does not depend on optical detection, yet has high detection sensitivity. The sensor is able to detect vapors from the plastic explosives pentaerythritol tetranitrate and hexahydro-1,3,5-triazine at levels below 10 parts per trillion within few seconds of exposure under ambient conditions. A differential measurement technique has yielded a rugged sensor that is unaffected by vibration and is able to function as a "sniffer." The microelectromechanical system sensor design allows for the incorporation of hundreds of microcantilevers with suitable coatings in order to achieve sufficient selectivity in the future, and thus could provide an inexpensive, unique platform for the detection of chemical, biological, and explosive materials.

Comparing CTH Simulations and Experiments on Explosively Loaded Rings

NASA Astrophysics Data System (ADS)

Braithwaite, C. H.; Aydelotte, B.; Thadhani, N. N.; Williamson, D. M.

2011-06-01

A series of experiments were conducted on explosively loaded rings for the purpose of studying fragmentation. In addition to the collection of fragments for analysis, the radial velocity of the expanding ring was measured with PDV and the arrangement was imaged using a high speed camera. Both the ring material and the material used as the explosive container were altered and the results compared with simulations performed in CTH. Good agreement was found between the simulations and the experiments. The maximum radial velocity attained was approximately 450 m/s, which was achieved through loading with a 5g PETN based charge.

Environmental Fate and Ecological Impact of Emerging Energetic Chemicals (ADN, DNAN and its Amino-Derivatives, PETN, NTO, NQ, FOX-7, and FOX-12) and an Insensitive Formulation

DTIC Science & Technology

2014-07-01

the two soils [12,32]. Chemical analyses of test soil (Fig. 4A) and earthworm tissue (Fig. 4B) showed that addition of earthworms to soil aided in...the soil DNAN concentration (30 mg/kg, measured prior to addition of earthworms to test soils). 3.0 ECOTOXICOLOGY OF NTO, NQ, FOX-7, AND FOX-12... addition , Sarlauska et al. [40] examined the toxicity of NTO by looking at selected enzymes isolated from pig, or a virus-transformed lamb kidney

Imaging standoff detection of explosives using widely tunable midinfrared quantum cascade lasers

NASA Astrophysics Data System (ADS)

Fuchs, Frank; Hugger, Stefan; Kinzer, Michel; Aidam, Rolf; Bronner, Wolfgang; Lösch, Rainer; Yang, Quankui; Degreif, Kai; Schnürer, Frank

2010-11-01

The use of a tunable midinfrared external cavity quantum cascade laser for the standoff detection of explosives at medium distances between 2 and 5 m is presented. For the collection of the diffusely backscattered light, a high-performance infrared imager was used. Illumination and wavelength tuning of the laser source was synchronized with the image acquisition, establishing a hyperspectral data cube. Sampling of the backscattered radiation from the test samples was performed in a noncooperative geometry at angles of incidence far away from specular reflection. We show sensitive detection of traces of trinitrotoluene and pentaerythritol tetranitrate on real-world materials, such as standard car paint, polyacrylics from backpacks, and jeans fabric. Concentrations corresponding to fingerprints were detected, while concepts for false alarm suppression due to cross-contaminations were presented.

Gaseous byproducts from high-temperature thermal conversion elemental analysis of nitrogen- and sulfur-bearing compounds with considerations for δ2H and δ18O analyses.

PubMed

Hunsinger, Glendon B; Tipple, Christopher A; Stern, Libby A

2013-07-30

High-temperature, conversion-reduction (HTC) systems convert hydrogen and oxygen in materials into H2 and CO for δ(2)H and δ(18)O measurements by isotope ratio mass spectrometry. HTC of nitrogen- and sulfur-bearing materials produces unintended byproduct gases that could affect isotope analyses by: (1) allowing isotope exchange reactions downstream of the HTC reactor, (2) creating isobaric or co-elution interferences, and (3) causing deterioration of the chromatography. This study characterizes these HTC byproducts. A HTC system (ThermoFinnigan TC/EA) was directly connected to a gas chromatograph/quadrupole mass spectrometer in scan mode (m/z 8 to 88) to identify the volatile products generated by HTC at conversion temperatures of 1350 °C and 1450 °C for a range of nitrogen- and sulfur-bearing solids [keratin powder, horse hair, caffeine, ammonium nitrate, potassium nitrate, ammonium sulfate, urea, and three nitrated organic explosives (PETN, RDX, and TNT)]. The prominent HTC byproduct gases include carbon dioxide, hydrogen cyanide, methane, acetylene, and water for all nitrogen-bearing compounds, as well as carbon disulfide, carbonyl sulfide, and hydrogen sulfide for sulfur-bearing compounds. The 1450 °C reactor temperature reduced the abundance of most byproduct gases, but increased the significant byproduct, hydrogen cyanide. Inclusion of a post-reactor chemical trap containing Ascarite II and Sicapent, in series, eliminated the majority of byproducts. This study identified numerous gaseous HTC byproducts. The potential adverse effects of these gases on isotope ratio analyses are unknown but may be mitigated by higher HTC reactor temperatures and purifying the products with a purge-and-trap system or with chemical traps. Published in 2013. This article is a U.S. Government work and is in the public domain in the USA.

Comparing CTH simulations and experiments on explosively loaded rings

NASA Astrophysics Data System (ADS)

Braithwaite, C. H.; Aydelotte, Brady; Collins, Adam; Thadhani, Naresh; Williamson, David Martin

2012-03-01

A series of experiments were conducted on explosively loaded metallic rings for the purpose of studying fragmentation. In addition to the collection of fragments for analysis, the radial velocity of the expanding ring was measured with photon Doppler velocimetry (PDV) and the arrangement was imaged using high speed photography. Both the ring material and the material used as the explosive container were altered and the results compared with simulations performed in CTH. Good agreement was found between the simulations and the experiments. The maximum radial velocity attained was approximately 380 m/s, which was achieved through loading with a 5g PETN based charge.

Ab initio study of energy transfer rates and impact sensitivities of crystalline explosives.

PubMed

Bernstein, Jonathan

2018-02-28

Impact sensitivities of various crystalline explosives were predicted by means of plane wave-density functional theory calculations. Crystal structures and complete vibrational spectra of TATB, PETN, FOX7, TEX, 14DNI, and β-HMX molecular crystals were calculated. A correlation between the phonon-vibron coupling (which is proportionally related to the energy transfer rate between the phonon manifold and the intramolecular vibrational modes) and impact sensitivities of secondary explosives was found. We propose a method, based on ab initio calculations, for the evaluation of impact sensitivities, which consequently can assist in screening candidates for chemical synthesis of high energetic materials.

Susceptibility Index of Explosives to Accidental Initiation

DTIC Science & Technology

1981-10-01

89 - ,I ~ .I•i / 2"•/ ’ / ". -] " •I I I - I -. . 27 TNB S f.: 90 90 90 _ - •0 .... ., .. . - 28 PBXN -5 S.I.: 106 106 75 74 75 91- I -- ItI / -d...S. 1. 1390 139 84 62 73 106 Al - -. - - - - I- - i - -A 39 PBXW-109 S,. .: 156* 156 86 66 76 89* 107 40 PBXN - 106 S.l.: 111w 97* 104 88 78 03 149* 107... PBXN -105 50/26/17/7 AP/AL/BINDER/RDX PBXN - 106 75/25 RDX/BINDER PENTOLITE 50/50 PETN/TNT PICRATOL 52/48 EXPLOSIVE D/TNT TRITONAL 80/20 TNT/AL 9007 90

Plasmonic enhanced terahertz time-domain spectroscopy system for identification of common explosives

NASA Astrophysics Data System (ADS)

Demiraǧ, Yiǧit; Bütün, Bayram; Özbay, Ekmel

2017-05-01

In this study, we present a classification algorithm for terahertz time-domain spectroscopy systems (THz-TDS) that can be trained to identify most commonly used explosives (C4, HMX, RDX, PETN, TNT, composition-B and blackpowder) and some non-explosive samples (lactose, sucrose, PABA). Our procedure can be used in any THz-TDS system that detects either transmission or reflection spectra at room conditions. After preprocessing the signal in low THz regime (0.1 - 3 THz), our algorithm takes advantages of a latent space transformation based on principle component analysis in order to classify explosives with low false alarm rate.

Ab initio study of energy transfer rates and impact sensitivities of crystalline explosives

NASA Astrophysics Data System (ADS)

Bernstein, Jonathan

2018-02-01

Impact sensitivities of various crystalline explosives were predicted by means of plane wave-density functional theory calculations. Crystal structures and complete vibrational spectra of TATB, PETN, FOX7, TEX, 14DNI, and β-HMX molecular crystals were calculated. A correlation between the phonon-vibron coupling (which is proportionally related to the energy transfer rate between the phonon manifold and the intramolecular vibrational modes) and impact sensitivities of secondary explosives was found. We propose a method, based on ab initio calculations, for the evaluation of impact sensitivities, which consequently can assist in screening candidates for chemical synthesis of high energetic materials.

Computations on Internal Blast from Titanium-Cased Charges in Air

DTIC Science & Technology

1984-07-01

formation and considerable temperature- dependent polymorphic transition . Oxygen is soluble in titanium metal to the extent of about 25 atom-percent, yielding...15 CSH8N4O1 2 NC Nitrocellulose, 13.3% N; -812.9 +3 C6H7N2.5010 HMX symn-Cyclotetramnethylene- + 77.4 0 tetranitramine, C4HSNBO8 Pentolite 50% PETN, 50...TNT; -97.9 -5 C6.1 6H6 .2 5N3.41085. Comp 8 65% RDX , 35% TNT; + 11.47 -9 C1 .96H2. 53N2.2202.68 TNT 2,4,6-Trinitrotoluene, +30.7 -25 p C7R 5N306 N2

Method to prepare Semtex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alcaraz, A; Dougan, A

This procedure requires the binder and uncoated RDX be prepared in separate steps, see Figure 1: (1) The binder and dye are mixed by agitation with a water-insoluble organic solvent (e.g., toluene), I; (2) The RDX/PETN is agitated thoroughly with water, II; (3) The binder solution I is added to the RDX/water mixture at II with thorough mixing to form a slurry III; (4) In the next step the solvent is distilled off at IV leaving resulting granules; (5) The next step is followed by filtration at V, which may be done by vacuum; (6) The composition is then driedmore » at VI to a dough-like consistency.« less

Detonation E. O. S. patterns for several explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, L.; Lee, E.L.; Mitchell, A.C.

1983-07-13

The available overdriven shockwave data for a number of explosives have been analyzed and compared. The data follow neither a constant gamma pattern nor the JWL EOS that fits expansion data to high accuracy. Modifications of the JWL function are proposed to correct for discrepancies and also to allow for the appropriate volume dependence of the Grueneisen constant indicated by previous and more recent work. The deviations from the JWL form of the equation of state appear directly above the CJ point for 9404 and PETN while Pentolite and TNT agree with this form over a portion of the Hugoniot.more » The comparisons with other experiments and a theoretical EOS indicate nonequilibrium behavior.« less

Relaxed structure of typical nitro explosives in the excited state: Observation, implication and application

NASA Astrophysics Data System (ADS)

Chu, Genbai; Yang, Zuhua; Xi, Tao; Xin, Jianting; Zhao, Yongqiang; He, Weihua; Shui, Min; Gu, Yuqiu; Xiong, Ying; Xu, Tao

2018-04-01

Understanding the structural, geometrical, and chemical changes that occur after an electronic excitation is essential to elucidate the inherent mechanism of nitro explosives. Herein, relaxed structures of typical nitro explosives in the lowest singlet excited state are investigated using time-dependent density functional theory. During the excitation process, the nitro group is activated and relaxes via geometrical change. The five explosives RDX, HMX, CL-20, PETN, and LLM-105 exhibit similar relaxed structures, and the impact sensitivity is related to their excitation energy. High-sensitivity δ-HMX has a lower excitation energy for relaxed structure than β-HMX. This study offers novel insight into energetic materials.

Detonator Performance Characterization using Multi-Frame Laser Schlieren Imaging

NASA Astrophysics Data System (ADS)

Clarke, Steven; Landon, Colin; Murphy, Michael; Martinez, Michael; Mason, Thomas; Thomas, Keith

2009-06-01

Multi-frame Laser Schlieren Imaging of shock waves produced by detonators in transparent witness materials can be used to evaluate detonator performance. We use inverse calculations of the 2D propagation of shock waves in the EPIC finite element model computer code to calculate a temporal-spatial-pressure profile on the surface of the detonator that is consistent with the experimental shock waves from the schlieren imaging. Examples of calculated 2D temporal-spatial-pressure profiles from a range of detonator types (EFI --exploding foil initiators, DOI -- direct optical initiation, EBW -- exploding bridge wire, hotwire), detonator HE materials (PETN, HMX, etc), and HE densities. Also pressure interaction profiles from the interaction of multiple shock waves will be shown. LA-UR-09-00909.

Characterization of Detonator Performance as a Function of Porosity via the Hayes Effect via Rogowski Coil

NASA Astrophysics Data System (ADS)

Nakamoto, Teagan; Parrack, Kristina; Smith, Dalton; Trujillo, Chris; Wilde, Zak; Gibson, John; Lodes, Rylie; Malcolm, Hayden

2017-06-01

Researchers experimented with a novel diagnostic to study the effects of porosity on detonator performance. The new diagnostic takes advantage of the detonation electric effect observed by Hayes (1966). Detonation-produced electrical charges induce a current in the detonator wire that may be detected by use of a Rogowski coil developed and tailored for the purpose. Data collected by the Rogowski coil were then used to characterize detonations. Researchers tested PETN charges of various porosity levels (as characterized by measured particle size and surface area) to study the effect of porosity on detonation characteristics. This novel method was compared with and verified by the well-established technique of using PVDF gauges for detonator response characterization.

Laser desorption with corona discharge ion mobility spectrometry for direct surface detection of explosives.

PubMed

Sabo, M; Malásková, M; Matejčík, S

2014-10-21

We present a new highly sensitive technique for the detection of explosives directly from the surface using laser desorption-corona discharge-ion mobility spectrometry (LD-CD-IMS). We have developed LD based on laser diode modules (LDM) and the technique was tested using three different LDM (445, 532 and 665 nm). The explosives were detected directly from the surface without any further preparation. We discuss the mechanism of the LD and the limitations of this technique such as desorption time, transport time and desorption area. After the evaluation of experimental data, we estimated the potential limits of detection of this method to be 0.6 pg for TNT, 2.8 pg for RDX and 8.4 pg for PETN.

Location and detection of explosive-contaminated human fingerprints on distant targets using standoff laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Lucena, P.; Gaona, I.; Moros, J.; Laserna, J. J.

2013-07-01

Detection of explosive-contaminated human fingerprints constitutes an analytical challenge of high significance in security issues and in forensic sciences. The use of a laser-induced breakdown spectroscopy (LIBS) sensor working at 31 m distance to the target, fitted with 2D scanning capabilities and designed for capturing spectral information from laser-induced plasmas of fingerprints is presented. Distribution chemical maps based on Na and CN emissions are used to locate and detect chloratite, DNT, TNT, RDX and PETN residues that have been deposited on the surface of aluminum and glass substrates. An effectiveness of 100% on fingerprints detection, regardless the substrate scanned, is reached. Environmental factors that affect the prevalence of the fingerprint LIBS response are discussed.

Determination of adiabatic ionization potentials and electron affinities of energetic molecules with the Gaussian-4 method

NASA Astrophysics Data System (ADS)

Manaa, M. Riad

2017-06-01

Adiabatic ionization potentials (IPad) and electron affinities (EAad) are determined with the Gaussian-4 (G4) method for the energetic molecules PETN, RDX, β-δ-HMX, CL-17, TNB, TNT, CL-14, DADNE, TNA, and TATB. The IPad and EAad values are in the range of 8.43-11.73 and 0.74-2.86 eV, respectively. Variations are due to substitutional effects of electron withdrawing and donating functional groups. Enthalpies of formation are also determined for several of these molecules to augment the list of recently reported G4 values. The calculated IPad and EAad provide quantitative assessment of such molecular properties as chemical hardness, molecular electronegativity, and "intrinsic" molecular physical hardness.

Single shot ultrafast dynamic ellipsometry (UDE) of laser-driven shocks in single crystal explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitley, Von H; Mcgrane, Shawn D; Moore, David S

2009-01-01

We report on the first experiments to measure states in shocked energetic single crystals with dynamic ellipsometry. We demonstrate that these ellipsometric techniques can produce reasonable Hugoniot values using small amounts of crystalline RDX and PETN. Pressures, particle velocities and shock velocities obtained using shocked ellipsometry are comparable to those found using gas-gun flyer plates and molecular dynamics calculations. The adaptation of the technique from uniform thin films of polymers to thick non-perfect crystalline materials was a significant achievement. Correct sample preparation proved to be a crucial component. Through trial and error, we were able to resolve polishing issues, samplemore » quality problems, birefringence effects and mounting difficulties that were not encountered using thin polymer films.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, Thomas Winfield; Brown, Kathryn Elizabeth; Chavez, David E.

Here, the synthesis and characterization of new 1,2,4-triazolyl and 4-nitro-pyrazolyl substituted tetrazine ligands has been achieved. The strongly electron deficient 1,2,4-triazolyl substituted ligands did not coordinate Fe(II) metal centers, while the mildly electron deficient 4-nitro-pyrazolyl substituted ligands did coordinate Fe(II) metal centers in a 2:1 ratio of ligand to metal. The thermal stability and mechanical sensitivity characteristics of the complexes are similar to the conventional explosive pentaerythritol tetranitrate. The complexes had strong absorption in the visible region of the spectrum that extended into the near-infrared. In spite of having improved oxygen balances, increased mechanical sensitivity, and similar absorption of NIRmore » light to recently reported Fe(II) tetrazine complexes, these newly synthesized explosives were more difficult to initiate with Nd:YAG pulsed laser light. More specifically, the complexes required lower densities (0.9 g/cm 3) to initiate at the same threshold utilized to initiate previous materials at higher densities (1.05 g/cm 3).« less

Crystal structure of bis[bis(4-azaniumylphenyl) sulfone] tetranitrate monohydrate

PubMed Central

Benahsene, Amani Hind; Bendjeddou, Lamia; Merazig, Hocine

2017-01-01

In the title compound, the hydrated tetra­(nitrate) salt of dapsone (4,4′-di­amino­diphenyl­sulfone), 2C12H14N2O2S2+·4NO3 −·H2O {alternative name: bis[bis­(4,4′-di­aza­niumylphen­yl) sulfone] tetra­nitrate monohydrate}, the cations are conformationally similar, with comparable dihedral angles between the two benzene rings in each of 70.03 (18) and 69.69 (19)°. In the crystal, mixed cation–anion–water mol­ecule layers lying parallel to the (001) plane are formed through N—H⋯O, O—H⋯O and C—H⋯O hydrogen-bonding inter­actions and these layers are further extended into an overall three-dimensional supra­molecular network structure. Inter-ring π–π inter­actions are also present [minimum ring centroid separation = 3.693 (3) Å]. PMID:29152359

Trace explosives sensor testbed (TESTbed)

NASA Astrophysics Data System (ADS)

Collins, Greg E.; Malito, Michael P.; Tamanaha, Cy R.; Hammond, Mark H.; Giordano, Braden C.; Lubrano, Adam L.; Field, Christopher R.; Rogers, Duane A.; Jeffries, Russell A.; Colton, Richard J.; Rose-Pehrsson, Susan L.

2017-03-01

A novel vapor delivery testbed, referred to as the Trace Explosives Sensor Testbed, or TESTbed, is demonstrated that is amenable to both high- and low-volatility explosives vapors including nitromethane, nitroglycerine, ethylene glycol dinitrate, triacetone triperoxide, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate, and hexahydro-1,3,5-trinitro-1,3,5-triazine. The TESTbed incorporates a six-port dual-line manifold system allowing for rapid actuation between a dedicated clean air source and a trace explosives vapor source. Explosives and explosives-related vapors can be sourced through a number of means including gas cylinders, permeation tube ovens, dynamic headspace chambers, and a Pneumatically Modulated Liquid Delivery System coupled to a perfluoroalkoxy total-consumption microflow nebulizer. Key features of the TESTbed include continuous and pulseless control of trace vapor concentrations with wide dynamic range of concentration generation, six sampling ports with reproducible vapor profile outputs, limited low-volatility explosives adsorption to the manifold surface, temperature and humidity control of the vapor stream, and a graphical user interface for system operation and testing protocol implementation.

Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

DOE Office of Scientific and Technical Information (OSTI.GOV)

C.J. Miller; G. Elias; N.C. Schmitt

2010-06-01

High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to specifically identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol using no sample cleanup prior to analysis. The methanol extracts were injected directly into several different column types and analyzed by HPLC-UV and/or GC-ECD. This paper describes general screening methods that weremore » used to determine the presence of explosives in unknown samples and techniques that have been optimized for quantification of each explosive from the substrate extracts.« less

On the relative utility of infrared (IR) versus terahertz (THz) for optical sensors

NASA Astrophysics Data System (ADS)

Johnson, T. J.; Valentine, N. B.; Gassman, P. L.; Atkinson, D. A.; Sharpe, S. W.; Williams, Steven D.

2007-09-01

Pacific Northwest National Laboratory (PNNL) has active programs investigating the optical absorption strengths of several types of molecules including toxic industrial chemicals (TICs), microbiological threats such as bacteria, as well as explosives such as RDX, PETN and TNT. While most of our work has centered on the mid-infrared domain (600 to 6,500 cm-1), more recent work has also included work in the far-infrared, also called the terahertz (THz) region (500 to ~8 cm-1). Using Fourier transform infrared spectroscopy, we have been able to compare the relative, and in some cases absolute, IR/THz cross sections of a number of species in the solid and liquid phases. The relative band strengths of a number of species of interest are discussed in terms of both experimental and computational results.

Hyperspectral image analysis for standoff trace detection using IR laser spectroscopy

NASA Astrophysics Data System (ADS)

Jarvis, J.; Fuchs, F.; Hugger, S.; Ostendorf, R.; Butschek, L.; Yang, Q.; Dreyhaupt, A.; Grahmann, J.; Wagner, J.

2016-05-01

In the recent past infrared laser backscattering spectroscopy using Quantum Cascade Lasers (QCL) emitting in the molecular fingerprint region between 7.5 μm and 10 μm proved a highly promising approach for stand-off detection of dangerous substances. In this work we present an active illumination hyperspectral image sensor, utilizing QCLs as spectral selective illumination sources. A high performance Mercury Cadmium Telluride (MCT) imager is used for collection of the diffusely backscattered light. Well known target detection algorithms like the Adaptive Matched Subspace Detector and the Adaptive Coherent Estimator are used to detect pixel vectors in the recorded hyperspectral image that contain traces of explosive substances like PETN, RDX or TNT. In addition we present an extension of the backscattering spectroscopy technique towards real-time detection using a MOEMS EC-QCL.

Molecular simulations of Crussard curves of detonation product mixtures at chemical equilibrium: Microscopic calculation of the Chapman-Jouguet state

NASA Astrophysics Data System (ADS)

Bourasseau, Emeric; Dubois, Vincent; Desbiens, Nicolas; Maillet, Jean-Bernard

2007-06-01

The simultaneous use of the Reaction Ensemble Monte Carlo (ReMC) method and the Adaptative Erpenbeck EOS (AE-EOS) method allows us to calculate direclty the thermodynamical and chemical equilibrium of a mixture on the hugoniot curve. The ReMC method allow to reach chemical equilibrium of detonation products and the AE-EOS method constraints ths system to satisfy the Hugoniot relation. Once the Crussard curve of detonation products has been established, CJ state properties may be calculated. An additional NPT simulation is performed at CJ conditions in order to compute derivative thermodynamic quantities like Cp, Cv, Gruneisen gama, sound velocity, and compressibility factor. Several explosives has been studied, of which PETN, nitromethane, tetranitromethane, and hexanitroethane. In these first simulations, solid carbon is eventually treated using an EOS.

Effects of heat-treatment and explosive brisance on fragmentation of high strength steel

NASA Astrophysics Data System (ADS)

Stolken, James; Kumar, Mukul; Gold, Vladimir; Baker, Ernest; Lawrence Livermore Nationa Laboratory Collaboration; Armament Research Development; Eng Collaboration

2011-06-01

Tubes of AISI-4340 steel were heat-treated to three distinct microstructures resulting in nominal hardness values of 25 Rc, 38 Rc and 48 Rc. The specimens were then explosively fragmented using TNT and PETN. The experiments were conducted in a contained firing facility with high fragment collection efficiency. Statistical analyses of recovered fragments were performed. Fragment rank-order statistics and generalized goodness-of-fit tests were used to characterize the fragment mass distributions. These analyses indicated significant interaction effects between the heat-treatment (and the resulting microstructure) and the explosive brisance. The role of the microstructure in relation to the yield-strength and toughness will also be discussed. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2003-08-05

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder, Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Catalyst for cracking kerosene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsie, C. H.

1985-06-04

A catalyst capable of cracking kerosene under lower pressure and temperature comprising kerosene; metal powder mixture of chromium powder, copper powder, lead powder, zinc powder, nickel powder, manganese powder in an amount of 12 to 13 parts by weight per 100 parts by weight of said kerosene; sulfuric acid in an amount of 15 to 30 parts by weight per 100 parts by weight of said kerosene; inorganic powder mixture of aluminum oxide powder, serpentine powder, alum powder, magnesium oxide powder, limestone powder, slake lime powder, silica powder, and granite powder in an amount of 150 to 170 parts bymore » weight per 100 parts by weight of said kerosene.« less

Detonation Performance Testing of LX-19

NASA Astrophysics Data System (ADS)

Vincent, Samuel; Aslam, Tariq; Jackson, Scott

2015-06-01

CL-20 was developed at the Naval Surface Weapons Center at China Lake, CA in the mid 80's. Being less sensitive than PETN, but considerably more powerful than HMX, it is the highest energy and density compound known among organic chemicals. LX-19 was developed at LLNL in the early 90's. It is a high-energy plastic bonded explosive, composed of 95.8 wt% CL-20 and 4.2 wt% Estane binder, and is similar to LX-14 (composed of HMX and Estane), but with greater sensitivity characteristics with use of the more energetic CL-20 explosive. We report detonation performance results for unconfined cylindrical rate sticks of LX-19. The experimental diameter effects are shown, along with detonation front shapes, and reaction zone profiles for different test diameters. This data is critical for calibration to Detonation Shock Dynamics (DSD). LA-UR-15-20672.

Unreacted Hugoniots for porous and liquid explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gustavsen, R.L.; Sheffield, S.A.

1993-08-01

Numerous authors have measured the Hugoniots of a variety of granular explosives pressed to different densities. Each explosive at each density was typically then treated as a unique material having its own Hugoniot. By combining methods used by Hayes, Sheffield and Mitchell (for describing the Hugoniot of HNS at various densities) with Hermann`s P-{alpha} model, it is only necessary to know some thermodynamic constants or the Hugoniot of the initially solid material and the porous material sound speed to obtain accurate unreacted Hugoniots for the porous explosive. We discuss application of this method to several materials including HMX, PETN, TNT,more » and Tetryl, as well as HNS. We also show that the ``Universal Liquid Hugoniot`` can be used to calculate the unreacted Hugoniot for liquid explosives. With this method only the ambient pressure sound speed and density are needed to predict the Hugoniot. Applications presented include nitromethane and liquid TNT.« less

Detection of Explosives Using Differential Laser-Induced Perturbation Spectroscopy with a Raman-based Probe.

PubMed

Oztekin, Erman K; Burton, Dallas J; Hahn, David W

2016-04-01

Explosives detection is carried out with a novel spectral analysis technique referred to as differential laser-induced perturbation spectroscopy (DLIPS) on thin films of TNT, RDX, HMX, and PETN. The utility of Raman spectroscopy for detection of explosives is enhanced by inducing deep ultraviolet laser perturbation on molecular structures in combination with a differential Raman sensing scheme. Principal components analysis (PCA) is used to quantify the DLIPS method as benchmarked against a traditional Raman scattering probe, and the related photo-induced effects on the molecular structure of the targeted explosives are discussed in detail. Finally, unique detection is observed with TNT samples deposited on commonly available background substrates of nylon and polyester. Overall, the data support DLIPS as a noninvasive method that is promising for screening explosives in real-world environments and backgrounds. © The Author(s) 2016.

Novel CE-MS technique for detection of high explosives using perfluorooctanoic acid as a MEKC and mass spectrometric complexation reagent.

PubMed

Brensinger, Karen; Rollman, Christopher; Copper, Christine; Genzman, Ashton; Rine, Jacqueline; Lurie, Ira; Moini, Mehdi

2016-01-01

To address the need for the forensic analysis of high explosives, a novel capillary electrophoresis mass spectrometry (CE-MS) technique has been developed for high resolution, sensitivity, and mass accuracy detection of these compounds. The technique uses perfluorooctanoic acid (PFOA) as both a micellar electrokinetic chromatography (MEKC) reagent for separation of neutral explosives and as the complexation reagent for mass spectrometric detection of PFOA-explosive complexes in the negative ion mode. High explosives that formed complexes with PFOA included RDX, HMX, tetryl, and PETN. Some nitroaromatics were detected as molecular ions. Detection limits in the high parts per billion range and linear calibration responses over two orders of magnitude were obtained. For proof of concept, the technique was applied to the quantitative analysis of high explosives in sand samples. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Photoactive energetic materials

DOEpatents

Chavez, David E.; Hanson, Susan Kloek; Scharff, Robert Jason; Veauthier, Jacqueline Marie; Myers, Thomas Winfield

2018-02-27

Energetic materials that are photoactive or believed to be photoactive may include a conventional explosive (e.g. PETN, nitroglycerine) derivatized with an energetic UV-absorbing and/or VIS-absorbing chromophore such as 1,2,4,5-tetrazine or 1,3,5-triazine. Absorption of laser light having a suitably chosen wavelength may result in photodissociation, decomposition, and explosive release of energy. These materials may be used as ligands to form complexes. Coordination compounds include such complexes with counterions. Some having the formula M(L).sub.n.sup.2+ were synthesized, wherein M is a transition metal and L is a ligand and n is 2 or 3. These may be photoactive upon exposure to a laser light beam having an appropriate wavelength of UV light, near-IR and/or visible light. Photoactive materials also include coordination compounds bearing non-energetic ligands; in this case, the counterion may be an oxidant such as perchlorate.

Hugoniot Measurements at Low Pressures in Tin Using 800 MeV proton Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Cynthia; Hogan, Gary E; King, Nicholas S. P.

2009-08-05

A 2cm long 8 mm diameter cylindrical tin target has been shocked to a pressure in the region of the {beta} {yields} {gamma} phase change using a small, low density PETN charge mounted on the opposite side of a stainless steel diaphragm. The density jump and shock velocity were measured radiographically as the shock wave moved through the sample and the pressure dropped, using the proton radiography facility at LANL. This provided a quasi-continuous record of the equations of state along the Hugoniot for the P1 wave from a shock velocity of 3.25 km/sec down to near the sound speed.more » Edge release effects were removed from the data using tomographic techniques. The data show evidence for a phase transition that extends over a broad pressure range. The data and analysis will be presented.« less

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2005-01-25

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2005-05-10

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2003-08-26

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2003-08-19

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2004-09-28

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2004-09-14

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2003-07-29

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Biaxially textured articles formed by powder metallurgy

DOEpatents

Goval, Amit; Williams, Robert K.; Kroeger, Donald M.

2005-06-07

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Laser initiation of Fe(II) complexes of 4-nitro-pyrazolyl substituted tetrazine ligands

DOE PAGES

Myers, Thomas Winfield; Brown, Kathryn Elizabeth; Chavez, David E.; ...

2017-02-01

Here, the synthesis and characterization of new 1,2,4-triazolyl and 4-nitro-pyrazolyl substituted tetrazine ligands has been achieved. The strongly electron deficient 1,2,4-triazolyl substituted ligands did not coordinate Fe(II) metal centers, while the mildly electron deficient 4-nitro-pyrazolyl substituted ligands did coordinate Fe(II) metal centers in a 2:1 ratio of ligand to metal. The thermal stability and mechanical sensitivity characteristics of the complexes are similar to the conventional explosive pentaerythritol tetranitrate. The complexes had strong absorption in the visible region of the spectrum that extended into the near-infrared. In spite of having improved oxygen balances, increased mechanical sensitivity, and similar absorption of NIRmore » light to recently reported Fe(II) tetrazine complexes, these newly synthesized explosives were more difficult to initiate with Nd:YAG pulsed laser light. More specifically, the complexes required lower densities (0.9 g/cm 3) to initiate at the same threshold utilized to initiate previous materials at higher densities (1.05 g/cm 3).« less

Rapid Quantitative Analysis of Multiple Explosive Compound Classes on a Single Instrument via Flow-Injection Analysis Tandem Mass Spectrometry.

PubMed

Ostrinskaya, Alla; Kunz, Roderick R; Clark, Michelle; Kingsborough, Richard P; Ong, Ta-Hsuan; Deneault, Sandra

2018-05-24

A flow-injection analysis tandem mass spectrometry (FIA MSMS) method was developed for rapid quantitative analysis of 10 different inorganic and organic explosives. Performance is optimized by tailoring the ionization method (APCI/ESI), de-clustering potentials, and collision energies for each specific analyte. In doing so, a single instrument can be used to detect urea nitrate, potassium chlorate, 2,4,6-trinitrotoluene, 2,4,6-trinitrophenylmethylnitramine, triacetone triperoxide, hexamethylene triperoxide diamine, pentaerythritol tetranitrate, 1,3,5-trinitroperhydro-1,3,5-triazine, nitroglycerin, and octohy-dro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine with sensitivities all in the picogram per milliliter range. In conclusion, FIA APCI/ESI MSMS is a fast (<1 min/sample), sensitive (~pg/mL LOQ), and precise (intraday RSD < 10%) method for trace explosive detection that can play an important role in criminal and attributional forensics, counterterrorism, and environmental protection areas, and has the potential to augment or replace several of the existing explosive detection methods. © 2018 American Academy of Forensic Sciences.

Biaxially textured articles formed by power metallurgy

DOEpatents

Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

2003-08-26

A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

Rheological, physical and sensorial evaluation of cookies supplemented with dairy powders.

PubMed

Sert, Durmuş; Demir, M Kürşat; Ertaş, Nilgün

2016-04-01

The effect of dairy powders (skim milk powder, butter milk powder, sodium caseinate, yoghurt powder, milk powder and colostrum powder) on cookie quality was studied. Cookies were tested for aw, calorimetric energy, diameter, thickness, spread ratio, breaking strength, colour, dough consistency and sensory evaluation. The lowest aw values were obtained for cookies containing colostrum powder; also the highest calorimetric energy values were obtained from the colostrum powder-added cookies. Diameter values of cookies with the addition of skim milk powder, butter milk powder, yoghurt powder and milk powder were higher than that of sodium caseinate and colostrum powder. The lowest spread ratio was measured in the cookie samples with added skim milk powder. The addition of yoghurt powder gave the highest breaking strength of cookies. Cookies with sodium caseinate addition exhibited the highest lightness (L*) values than the other cookies with different dairy powders. Cookies prepared with butter milk powder received the highest scores for colour, appearance, texture, crispness and overall acceptability. © The Author(s) 2015.

Plant tissue analysis for explosive compounds in phytoremediation and phytoforensics.

PubMed

Karnjanapiboonwong, Adcharee; Mu, Ruipu; Yuan, Yuan; Shi, Honglan; Ma, Yinfa; Burken, Joel G

2012-01-01

Plant tissue analysis methods were evaluated for six explosive compounds to assess uptake and phytoforensic methods development to quantify explosives in plant to obtain the plant data for the evaluation of explosive contamination in soil and groundwater. Four different solvent mixtures containing acetonitrile or methanol were tested at variable extraction ratios to compare the extraction efficiency for six explosive compounds: 2,4,6-trinitrotoluene (TNT), pentaerythritoltetranitrate (PETN), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2-amino-4,6-dinitrotoluene (2ADNT), and 2,4-Dinitroanisole (DNAN), in Laurel Willow (Salix pentandra) stem and range grass Big Bluestem (Andropogon gerardii) using LC-MS/MS. Plant tissues were spiked with 500 ng/g of explosives and extracted using ultrasonically-assisted solvent extraction. With the ratio of fresh plant mass to solvent volume of 1:20 for willow and 1:40 for big bluestem grass, results indicated that all explosives in willow except HMX were extracted at higher than 73.3% by using 20 mL of methanol, 50:50 (v/v) methanol:water, or acetonitrile, whereas HMX was extracted with the highest recovery of 61.3% by 20 mL of acetonitrile. In big bluestem grass, the most effective solvents were 20 mL of either methanol or 50:50 (v/v) methanol:water for PETN extraction with a recovery of higher than 101.2% and 20 mL of 50:50 (v/v) methanol:water for HMX, RDX, TNT, 2ADNT, and DNAN extraction with a recovery of 83.8%, 104.4%, 97.5%, 80.7%, and 108.2%, respectively. However, unlike methanol and acetonitrile, 50:50 (v/v) methanol:water provided no problem of leading or split peak in chromatogram; therefore, it was preferred in the test and performed a method validation. Results indicated that 50:50 (v/v) methanol:water provided good repeatability and recovery and method detection limits at 0.5-20 ng/g fresh weight or 8.8-61.3 ng/g dry weight. Overall, results suggested that solvent extraction efficiency of explosives in plant was influenced by plant species and solvent used, and method presented here was believed to provide the preliminary data with respect to the analysis of simultaneous explosives in plants with LC-MS/MS.

Powder treatment process

DOEpatents

Weyand, J.D.

1988-02-09

Disclosed are: (1) a process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder. 2 figs.

Powder treatment process

DOEpatents

Weyand, John D.

1988-01-01

(1) A process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder.

Method and product for phosphosilicate slurry for use in dentistry and related bone cements

DOEpatents

Wagh, Arun S.; Primus, Carolyn

2006-08-01

The present invention is directed to magnesium phosphate ceramics and their methods of manufacture. The composition of the invention is produced by combining a mixture of a substantially dry powder component with a liquid component. The substantially dry powder component comprises a sparsely soluble oxide powder, an alkali metal phosphate powder, a sparsely soluble silicate powder, with the balance of the substantially dry powder component comprising at least one powder selected from the group consisting of bioactive powders, biocompatible powders, fluorescent powders, fluoride releasing powders, and radiopaque powders. The liquid component comprises a pH modifying agent, a monovalent alkali metal phosphate in aqueous solution, the balance of the liquid component being water. The use of calcined magnesium oxide as the oxide powder and hydroxylapatite as the bioactive powder produces a self-setting ceramic that is particularly suited for use in dental and orthopedic applications.

Preparation of tris(8-hydroxyquinolinato)aluminum thin films by sputtering deposition using powder and pressed powder targets

NASA Astrophysics Data System (ADS)

Kawasaki, Hiroharu; Ohshima, Tamiko; Yagyu, Yoshihito; Ihara, Takeshi; Tanaka, Rei; Suda, Yoshiaki

2017-06-01

Tris(8-hydroxyquinolinato)aluminum (Alq3) thin films, for use in organic electroluminescence displays, were prepared by a sputtering deposition method using powder and pressed powder targets. Experimental results suggest that Alq3 thin films can be prepared using powder and pressed powder targets, although the films were amorphous. The surface color of the target after deposition became dark brown, and the Fourier transform infrared spectroscopy spectrum changed when using a pressed powder target. The deposition rate of the film using a powder target was higher than that using a pressed powder target. That may be because the electron and ion densities of the plasma generated using the powder target are higher than those when using pressed powder targets under the same deposition conditions. The properties of a thin film prepared using a powder target were almost the same as those of a film prepared using a pressed powder target.

77 FR 28252 - Oral Dosage Form New Animal Drugs; Change of Sponsor; Griseofulvin Powder; Levamisole...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

... Hydrochloride Powder; Oxytetracycline Powder AGENCY: Food and Drug Administration, HHS. ACTION: Final rule..., levamisole hydrochloride soluble powder, and oxytetracycline hydrochloride soluble powder from Teva Animal... Griseofulvin Powder, ANADAs 200-146 and 200-247 for Oxytetracycline Hydrochloride Soluble Powder, and ANADAs...

Preparation of titanium diboride powder

DOEpatents

Brynestad, Jorulf; Bamberger, Carlos E.

1985-01-01

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Aluminum powder metallurgy processing

NASA Astrophysics Data System (ADS)

Flumerfelt, Joel Fredrick

In recent years, the aluminum powder industry has expanded into non-aerospace applications. However, the alumina and aluminum hydroxide in the surface oxide film on aluminum powder require high cost powder processing routes. A driving force for this research is to broaden the knowledge base about aluminum powder metallurgy to provide ideas for fabricating low cost aluminum powder components. The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization commercial inert gas atomization and gas atomization reaction synthesis (GARS). The commercial atomization methods are bench marks of current aluminum powder technology. The GARS process is a laboratory scale inert gas atomization facility. A benefit of using pure aluminum powders is an unambiguous interpretation of the results without considering the effects of alloy elements. A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

Preparation of metal diboride powders

DOEpatents

Brynestad, J.; Bamberger, C.E.

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group of consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Effect of particle size on mixing degree in dispensation.

PubMed

Nakamura, Hitoshi; Yanagihara, Yoshitsugu; Sekiguchi, Hiroko; Ohtani, Michiteru; Kariya, Satoru; Uchino, Katsuyoshi; Suzuki, Hiroshi; Iga, Tatsuji

2004-03-01

By using lactose colored with erythrocin, we examined the effect of particle size on mixing degree during the preparation of triturations with a mortar and pestle. We used powders with different distributions of particle sizes, i.e., powder that passed through 32-mesh but was trapped on a 42-mesh sieve (32/42-mesh powder), powder that passed through a 42-mesh sieve but was trapped on a 60-mesh sieve (42/60-mesh powder), powder that passed through a 60-mesh sieve but was trapped on a 100-mesh sieve (60/100-mesh powder), and powder that passes through a 100-mesh sieve (> 100-mesh powder). The mixing degree of colored powder and non-colored powder whose distribution of particle sizes was the same as that of the colored powder was excellent. The coefficient of variation (CV) value of the mixing degree was 6.08% after 40 rotations when colored powder was mixed with non-colored powder that both passed through a 100-mesh sieve. The CV value of the mixing degree was low in the case of mixing of colored and non-colored powders with different particle size distributions. After mixing, about 50% of 42/60-mesh powder had become smaller particles, whereas the distribution of particle sizes was not influenced by the mixing of 60/100-mesh powder. It was suggested that the mixing degree is affected by distribution of particle sizes. It may be important to determine the mixing degrees for drugs with narrow therapeutic ranges.

Silicon nitride/silicon carbide composite powders

DOEpatents

Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

1996-06-11

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Particle Morphology Effects on Flow Characteristics of PS304 Plasma Spray Coating Feedstock Powder Blend

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; DellaCorte, Christopher; Eylon, Daniel

2002-01-01

The effects of BaF2-CaF 2 particle morphology on PS304 feedstock powder flow ability have been investigated. BaF2-CaF2 eutectic powders were fabricated by comminution (angular) and by gas atomization (spherical). The fluoride powders were added incrementally to the other powder constituents of the PS304 feedstock: nichrome, chromia, and silver powders. A linear relationship between flow time and concentration of BaF2-CaF2 powder was found. Flow of the powder blend with spherical BaF2-CaF2 was better than the angular BaF2-CaF2. Flow ability of the powder blend with angular fluorides decreased linearly with increasing fluoride concentration. Flow of the powder blend with spherical fluorides was independent of fluoride concentration. Results suggest that for this material blend, particle morphology plays a significant role in powder blend flow behavior, offering potential methods to improve powder flow ability and enhance the commercial potential. These findings may have applicability to other difficult-to-flow powders such as cohesive ceramics.

Review of the Methods for Production of Spherical Ti and Ti Alloy Powder

NASA Astrophysics Data System (ADS)

Sun, Pei; Fang, Zhigang Zak; Zhang, Ying; Xia, Yang

2017-10-01

Spherical titanium alloy powder is an important raw material for near-net-shape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.

Silicon nitride/silicon carbide composite densified materials prepared using composite powders

DOEpatents

Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

1997-07-01

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

[Impact of directly compressed auxiliary materials on powder property of fermented cordyceps powder].

PubMed

Chen, Li-Hua; Yue, Guo-Chao; Guan, Yong-Mei; Yang, Ming; Zhu, Wei-Feng

2014-01-01

To investigate such physical indexes as hygroscopicity, angle of repose, bulk density, fillibility of compression of mixed powder of directly compressed auxiliary materials and fermented cordyceps powder by using micromeritic study methods. The results showed that spray-dried lactose Flowlac100 and microcrystalline cellulose Avicel PH102 had better effect in liquidity and compressibility on fermented cordyceps powder than pregelatinized starch. The study on the impact of directly compressed auxiliary materials on the powder property of fermented cordyceps powder had guiding significant to the research of fermented cordyceps powder tablets, and could provide basis for the development of fermented cordyceps powder tablets.

New manufacturing method for Fe-Si magnetic powders using modified pack-cementation process

NASA Astrophysics Data System (ADS)

Byun, Ji Young; Kim, Jang Won; Han, Jeong Whan; Jang, Pyungwoo

2013-03-01

This paper describes a new method for making Fe-Si magnetic powders using a pack-cementation process. It was found that Fe-Si alloy powders were formed by a reaction of the pack mixture of Fe, Si, NaF, and Al2O3 powders at 900 °C for 24 h under a hydrogen atmosphere. Separation of the Fe-Si alloy powders was dependent on the particle size of the Fe powders in the pack. For small Fe powders, magnetic separation in a medium of strong alkali solution was recommended. But, for relatively larger Fe powders, the Fe-Si alloy powders were easily separated from Al2O3 powders using a magnet in air atmosphere. The Si content in the Fe-Si magnetic powders were easily controlled by changing the weight ratio of Si to (Si+Fe) in the pack.

Predicting the crystalline and porous equations of state for secondary explosives

NASA Astrophysics Data System (ADS)

Wixom, Ryan; Damm, David

2013-06-01

Accurate simulations of energetic material response necessitate accurate unreacted equations of state at pressures much higher than even the C-J state. Unfortunately, for reactive materials, experimental data at high pressures may be unattainable, and extrapolation from low-pressure data results in unacceptable uncertainty. In addition to being low-pressure, the available data is typically limited to the porous state. The fully-dense, or crystalline, equation of state is required for building mesoscale simulations of the dynamic response of energetic materials. We have used quantum molecular dynamics to predict the Hugoniots and 300 K isotherms of crystalline PETN, HNS, CL-20 and TATB up to pressures not attainable in experiments. The porous Hugoniots for these materials were then analytically obtained and are validated by comparison with available data. Our calculations for TATB confirm the presence of a kink in the Hugoniot, and the softening of the shock response is explained in terms of a change in molecular conformation and the loss of aromaticity.

Physical and Chemical Microstructural Damage in Pressed CL-20 explosives

NASA Astrophysics Data System (ADS)

Demol, Gauthier; Sandusky, Harold W.

1999-06-01

Based upon its molecular composition, its structure, and its heat of formation, it was expected that CL-20 (hexanitrohexaazaisowurtzitane) would be more energetic and more sensitive than RDX and HMX. Reports of batch-to-batch variations in the sensitivity of neat CL-20 have led to its sensitivity being ranked in the range between the sensitivity of RDX and that of PETN. The ultimate utility of CL-20 as an ingredient in explosive and propellant formulations will depend upon the ability to understand the factors that are responsible for this batch-to-batch variability, and to control the sensitivity in formulations within acceptable limits. This work is a characterization of CL-20 at various stages in its life cycle. The evolution of damage from the initial neat crystals of CL-20 to the ready-to-use pressed pellets will be described. This characterization includes physical documentation using light microscopy and Scanning Electron Microscopy. Spatially resolved chemical analysis is also performed using Fourier-Transform Infrared Spectroscopy.

Imaging standoff trace detection of explosives using IR-laser based backscattering

NASA Astrophysics Data System (ADS)

Fuchs, F.; Hugger, S.; Jarvis, J.; Yang, Q. K.; Ostendorf, R.; Schilling, Ch.; Bronner, W.; Driad, R.; Aidam, R.; Wagner, J.

2016-05-01

We perform active hyperspectral imaging using tunable mid-infrared (MIR) quantum cascade lasers for contactless identification of solid and liquid contaminations on surfaces. By collecting the backscattered laser radiation with a camera, a hyperspectral data cube, containing the spatially resolved spectral information of the scene is obtained. Data is analyzed using appropriate algorithms to find the target substances even on substrates with a priori unknown spectra. Eye-save standoff detection of residues of explosives and precursors over extended distances is demonstrated and the main purpose of our system. Using a MIR EC-QCL with a tuning range from 7.5 μm to 10 μm, detection of a large variety of explosives, e.g. TNT, PETN and RDX and precursor materials such as Ammonium Nitrate could be demonstrated. In a real world scenario stand-off detection over distances of up to 20 m could be successfully performed. This includes measurements in a post blast scenario demonstrating the potential of the technique for forensic investigations.

Predicting Trigger Bonds in Explosive Materials through Wiberg Bond Index Analysis.

PubMed

Harper, Lenora K; Shoaf, Ashley L; Bayse, Craig A

2015-12-21

Understanding the explosive decomposition pathways of high-energy-density materials (HEDMs) is important for developing compounds with improved properties. Rapid reaction rates make the detonation mechanisms of HEDMs difficult to understand, so computational tools are used to predict trigger bonds-weak bonds that break, leading to detonation. Wiberg bond indices (WBIs) have been used to compare bond densities in HEDMs to reference molecules to provide a relative scale for the bond strength to predict the activated bonds most likely to break to trigger an explosion. This analysis confirms that X-NO2 (X=N,C,O) bonds are trigger linkages in common HEDMs such as TNT, RDX and PETN, consistent with previous experimental and theoretical studies. Calculations on a small test set of substituted tetrazoles show that the assignment of the trigger bond depends upon the functionality of the material and that the relative weakening of the bond correlates with experimental impact sensitivities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emulsion based cast booster - a priming system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, R.N.; Mishra, A.K.

2005-07-01

This paper explores the potential of emulsion based cast booster to be used as primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made for comparative study between conventional cast booster and emulsion based cast booster in terms of the initiation process developed and their capability to develop and maintain the stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument. During this study three blasts have been monitored. In each blast two holes have been selected for study, the first hole being initiatedmore » with conventional cast booster while the other one with emulsion based cast booster. The findings of the study advocates that emulsion based cast booster is capable of efficient priming of bulk delivered column explosive with stable detonation process in the column. Further, the booster had advantages over the conventional PETN/TNT based cast booster. 5 refs., 2 figs., 1 tab., 1 photo.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 4. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 3. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 1. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the and 13 specific high explosive test sites. The samples were screened for semi-volatile organic PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives or degradation products weremore » identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 2. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosivesmore » or degradation products were identified. Semi-volatile organic compounds were found in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 5. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Appraisal of UTIAS implosion-driven hypervelocity launchers and shock tubes.

NASA Technical Reports Server (NTRS)

Glass, I. I.

1972-01-01

A critical appraisal is made of the design, research, development, and operation of the novel UTIAS implosion-driven hypervelocity launchers and shock tubes. Explosively driven (PbN6-lead azide, PETN-pentaerythritetetranitrate) implosions in detonating stoichiometric hydrogen-oxygen mixtures have been successfully developed as drivers for hypervelocity launchers and shock tubes in a safe and reusable facility. Intense loadings at very high calculated pressures, densities, and temperatures, at the implosion center, cause severe problems with projectile integrity. Misalignment of the focal point can occur and add to the difficulty in using small caliber projectiles. In addition, the extreme driving conditions cause barrel expansion, erosion, and possible gas leakage from the base to the head of the projectile which cut the predicted muzzle velocities to half or a third of the lossless calculated values. However, in the case of a shock-tube operation these difficulties are minimized or eliminated and the possibilities of approaching Jovian reentry velocities are encouraging.

Biocatalysis with thermostable enzymes: structure and properties of a thermophilic 'ene'-reductase related to old yellow enzyme.

PubMed

Adalbjörnsson, Björn V; Toogood, Helen S; Fryszkowska, Anna; Pudney, Christopher R; Jowitt, Thomas A; Leys, David; Scrutton, Nigel S

2010-01-25

We report the crystal structure of a thermophilic "ene" reductase (TOYE) isolated from Thermoanaerobacter pseudethanolicus E39. The crystal structure reveals a tetrameric enzyme and an active site that is relatively large compared to most other structurally determined and related Old Yellow Enzymes. The enzyme adopts higher order oligomeric states (octamers and dodecamers) in solution, as revealed by sedimentation velocity and multiangle laser light scattering. Bead modelling indicates that the solution structure is consistent with the basic tetrameric structure observed in crystallographic studies and electron microscopy. TOYE is stable at high temperatures (T(m)>70 degrees C) and shows increased resistance to denaturation in water-miscible organic solvents compared to the mesophilic Old Yellow Enzyme family member, pentaerythritol tetranitrate reductase. TOYE has typical ene-reductase properties of the Old Yellow Enzyme family. There is currently major interest in using Old Yellow Enzyme family members in the preparative biocatalysis of a number of activated alkenes. The increased stability of TOYE in organic solvents is advantageous for biotransformations in which water-miscible organic solvents and biphasic reaction conditions are required to both deliver novel substrates and minimize product racemisation.

Free radical interactions between raw materials in dry soup powder.

PubMed

Raitio, Riikka; Orlien, Vibeke; Skibsted, Leif H

2011-12-01

Interactions at the free radical level were observed between dry ingredients in cauliflower soup powder, prepared by dry mixing of ingredients and rapeseed oil, which may be of importance for quality deterioration of such dry food products. The free radical concentrations of cauliflower soup powder, obtained by electron spin resonance (ESR) spectroscopy, rapidly become smaller during storage (40°C and relative humidity of 75%) than the calculated concentrations of free radicals based on the free radical concentrations of the powder ingredients used to make the soup powder and stored separately under similar conditions. Similarly, free radical concentrations decreased faster when any combination of two powder ingredients (of the three major ingredients of the soup powder) were mixed together and stored at 50°C for 1week than when each powder component was stored separately. Furthermore, yeast extract powder was found to play a key role when free radical interactions between powder ingredients occurred. The incubation of rapeseed oil with powder ingredients at 45°C for 24h, indicated the ability of cauliflower powder to increase the concentration of hydroperoxides in rapeseed oil, while yeast extract powder was found to prevent this hydroperoxide formation. Copyright © 2011 Elsevier Ltd. All rights reserved.

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine equivalent...

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine equivalent...

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine equivalent...

[Improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology].

PubMed

Zeng, Rong-Gui; Jiang, Qie-Ying; Liao, Zheng-Gen; Zhao, Guo-Wei; Luo, Yun; Luo, Juan; Lv, Dan

2016-06-01

To study the improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology. The 1% hydrophobic silica nanoparticles were used as surface modifier, and andrographis extract powder was taken as a model drug. Three different techniques were used for coating model drugs, with angle of repose, compressibility, flat angle and cohesion as the comprehensive evaluation indexes for the powder flowability. The powder particle size and the size distribution were measured by Mastersizer 2000. FEI scanning electron microscope was used to observe the surface morphology and structure of the powder. The percentage of Si element on the powder surface was measured by energy dispersive spectrometer. The hygroscopicity of powder was determined by Chinese pharmacopoeia method. All of the three techniques can improve the flowability of powder extract. In particular, hygroscopicity of extract powder can also be improved by dispersion and then high-speed mixing, which can produce a higher percentage of Si element on the powder surface. The improvement principle may be correlated with a modifier adhered to the powder surface. Copyright© by the Chinese Pharmaceutical Association.

Spheroidization of molybdenum powder by radio frequency thermal plasma

NASA Astrophysics Data System (ADS)

Liu, Xiao-ping; Wang, Kuai-she; Hu, Ping; Chen, Qiang; Volinsky, Alex A.

2015-11-01

To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency (RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 µm, and the tap density is increased from 2.7 to 6.2 g/cm3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders.

A comparison of mango seed kernel powder, mango leaf powder and Manilkara zapota seed powder for decolorization of methylene blue dye and antimicrobial activity.

PubMed

Sundararaman, B; Muthuramu, K L

2016-11-01

The waste mango seed generated from mango pulp industry in India is a major problem in handling the waste and hence, conversion of mango seed kernel. Mango seeds were collected and processed for oil extraction. Decolorization of methylene blue was achieved by mango seed kernel powder, mango leaf powder and Manilkara zapota seed powder. Higher efficiency was attained in mango seed kernel powder when compared to mango leaf powder and Manilkara zapota seed powder. A 60 to 95 % of removal efficiency was achieved by varying concentration. Effect of pH, dye concentration, adsorbent dosage and temperature were studied. Mango seed kernel powder is a better option that can be used as an adsorbent for the removal of methylene blue and basic red dye from its aqueous solutions.

Influence of Ultrafine 2CaO·SiO₂ Powder on Hydration Properties of Reactive Powder Concrete.

PubMed

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-09-17

In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.

Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

PubMed Central

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-01-01

In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system. PMID:28793560

Improved Small-Particle Powders for Plasma Spraying

NASA Technical Reports Server (NTRS)

Nguyen, QuynhGiao, N.; Miller, Robert A.; Leissler, George W.

2005-01-01

Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmental barrier coatings. Heretofore, plasma-sprayed coatings have typically ranged in thickness from 125 to 1,800 micrometers. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedently small thicknesses of the order of 25 micrometers. Plasma spraying involves feeding a powder into a hot, high-velocity plasma jet. The individual powder particles melt in the plasma jet as they are propelled towards a substrate, upon which they splat to build up a coating. In some cases, multiple coating layers are required. The size range of the powder particles necessarily dictates the minimum thickness of a coating layer needed to obtain uniform or complete coverage. Heretofore, powder particle sizes have typically ranged from 40 to 70 micrometers; as a result, the minimum thickness of a coating layer for complete coverage has been about 75 micrometers. In some applications, thinner coatings or thinner coating layers are desirable. In principle, one can reduce the minimum complete-coverage thickness of a layer by using smaller powder particles. However, until now, when powder particle sizes have been reduced, the powders have exhibited a tendency to cake, clogging powder feeder mechanisms and feed lines. Hence, the main problem is one of synthesizing smaller-particle powders having desirable flow properties. The problem is solved by use of a process that begins with a spray-drying subprocess to produce spherical powder particles having diameters of less than 30 micrometers. (Spherical-particle powders have the best flow properties.) The powder is then passed several times through a commercial sifter with a mesh to separate particles having diameters less than 15 micrometers. The resulting fine, flowable powder is passed through a commercial fluidized bed powder feeder into a plasma spray jet.

Vacuum powder injector and method of impregnating fiber with powder

NASA Astrophysics Data System (ADS)

Working, Dennis C.

1993-05-01

A method and apparatus uniformly impregnate stranded material with dry powder such as low solubility, high melt flow polymer powder to produce, for example, composite prepregs. The stranded material is expanded in an impregnation chamber by an influx of air so that the powder, which may enter through the same inlet as the air, penetrates to the center of the stranded material. The stranded material then is contracted for holding the powder therein. The stranded material and powder may be pulled through the impregnation chamber in the same direction by vacuum. Larger particles of powder which do not fully penetrate the stranded material may be combed into the stranded material and powder which does not impregnate the stranded material may be collected and reused.

Vacuum powder injector and method of impregnating fiber with powder

NASA Technical Reports Server (NTRS)

Working, Dennis C. (Inventor)

1993-01-01

A method and apparatus uniformly impregnate stranded material with dry powder such as low solubility, high melt flow polymer powder to produce, for example, composite prepregs. The stranded material is expanded in an impregnation chamber by an influx of air so that the powder, which may enter through the same inlet as the air, penetrates to the center of the stranded material. The stranded material then is contracted for holding the powder therein. The stranded material and powder may be pulled through the impregnation chamber in the same direction by vacuum. Larger particles of powder which do not fully penetrate the stranded material may be combed into the stranded material and powder which does not impregnate the stranded material may be collected and reused.

Spheroidization of glass powders for glass ionomer cements.

PubMed

Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

2004-08-01

Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs.

Effects of humidity on the magnetic and woody characteristics of powder-type magnetic wood

NASA Astrophysics Data System (ADS)

Oka, H.; Tokuta, H.; Namizaki, Y.; Sekino, N.

2004-05-01

Among three types of proposed magnetic wood, powder-type magnetic wood can be made of recycled magnetic materials from IT devices, consumer electronics and waste wood. Because of its wood powder content, powder-type magnetic wood shows special characteristics different from those of typical magnetic materials. We focused on the relationship between humidity and magnetic characteristics of powder-type magnetic wood. The magnetic powder ratio, wood powder density and magnetic binder density were all examined as parameters for AC permeability.

Negative-ion formation in the explosives RDX, PETN, and TNT using the Reversal Electron Attachment Detection (READ) technique

NASA Technical Reports Server (NTRS)

Chutijian, Ara; Boumsellek, S.; Alajajian, S. H.

1992-01-01

In the search for high sensitivity and direct atmospheric sampling of trace species, techniques have been developed such as atmospheric-sampling, glow-discharge ionization (ASGDI), corona discharge, atmospheric pressure ionization (API), electron-capture detection (ECD), and negative-ion chemical ionization (NICI) that are capable of detecting parts-per-billion to parts-per-trillion concentrations of trace species. These techniques are based on positive- or negative-ion formation via charge-transfer to the target, or electron capture under multiple-collision conditions in a Maxwellian distribution of electron energies at the source temperature. One drawback of the high-pressure, corona- or glow-discharge devices is that they are susceptible to interferences either through indistinguishable product masses, or through undesired ion-molecule reactions. The ASGDI technique is relatively immune from such interferences, since at target concentrations of less than 1 ppm the majority of negative ions arises via electron capture rather than through ion-molecule chemistry. A drawback of the conventional ECD, and possibly of the ASGDI, is that they exhibit vanishingly small densities of electrons with energies in the range 0-10 millielectron volts (meV), as can be seen from a typical Maxwellian electron energy distribution function at T = 300 K. Slowing the electrons to these subthermal (less than 10 meV) energies is crucial, since the cross section for attachment of several large classes of molecules is known to increase to values larger than 10(exp -12) sq cm at near-zero electron energies. In the limit of zero energy these cross sections are predicted to diverge as epsilon(exp -1/2), where epsilon is the electron energy. In order to provide a better 'match' between the electron energy distribution function and attachment cross section, a new concept of attachment in an electrostatic mirror was developed. In this scheme, electrons are brought to a momentary halt by reversing their direction with electrostatic fields. At this turning point the electrons have zero or near-zero energy. A beam of target molecules is introduced, and the resultant negative ions extracted. This basic idea has been recently improved to allow for better reversal geometry, higher electron currents, lower backgrounds, and increased negative-ion extraction efficiency. We present herein application of the so-called reversal electron attachment detector (READ) to the study of negative-ion formation in the explosives molecules RDX, PETN, and TNT under single-collision conditions.

Reducing metal alloy powder costs for use in powder bed fusion additive manufacturing: Improving the economics for production

NASA Astrophysics Data System (ADS)

Medina, Fransisco

Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for titanium powder continues to increase, the price also increases. Titanium spheroidized powder from different vendors has a price range from 260/kg-450/kg, other spheroidized alloys such as Niobium can cost as high as $1,200/kg. Alternative titanium powders produced from methods such as the Titanium Hydride-Dehydride (HDH) process and the Armstrong Commercially Pure Titanium (CPTi) process can be fabricated at a fraction of the cost of powders fabricated via gas atomization. The alternative powders can be spheroidized and blended. Current sectors in additive manufacturing such as the medical industry are concerned that there will not be enough spherical powder for production and are seeking other powder options. It is believed the EBM technology can use a blend of spherical and angular powder to build fully dense parts with equal mechanical properties to those produced using traditional powders. Some of the challenges with angular and irregular powders are overcoming the poor flow characteristics and the attainment of the same or better packing densities as spherical powders. The goal of this research is to demonstrate the feasibility of utilizing alternative and lower cost powders in the EBM process. As a result, reducing the cost of the raw material to reduce the overall cost of the product produced with AM. Alternative powders can be made by blending or re-spheroidizing HDH and CPTi powders. Machine modifications were performed to allow the testing and manufacturing with these low cost alternative powders. A comparison was made between alternative powders and gas atomized powders. Powders were compared in terms of morphology and at the microstructural level. Flowability of different powder blends was also measured. Finally, a comparison of parts fabricated from the multiple powder blends and gas atomized powder was made. It has been demonstrated that powder blending can produce fully dense parts in the Arcam system by utilizing the double melt technique or HIPing the built pars. The double melt technique increased the density of the sample part and modified the microstructure into finer martensitic grains. The HIP process can make a part fully dense regardless of what percentage of HDH powder blending is used. The HIP process yielded the same microstructure, regardless of the grain structure it started with. This research allows for the reduction of costs using titanium powders in the EBM system, but can also be implemented with more costly elements and alloys using other metal AM technologies. This includes niobium, tantalum, and nickel-based superalloys for use in various industries.

Mechanical Performance Test of Rubber-Powder Modified Concrete

NASA Astrophysics Data System (ADS)

Zhang, Yan Cong; Gao, Ling Ling

2018-06-01

A number of rubber cement concrete specimens that rubber powder dosage different were obtained using same cement, water and fine aggregates, by adjusting the dosage of rubber powder. Then it was used to research the influence of rubber powder dosage on performance of cement concrete by measuring its liquidity, strength and toughness. The results show that: when water-cement ratio was equal and rubber powder replacing the same volume sand, the fluidity of cement concrete almost linear increased with rubber powder dosage increasing. With dosage of rubber powder increasing, compressive strength and flexural strength reduced, but toughness linear growth trend when dosage of rubber powder less 30%.

Characterization of powdered fish heads for bone graft biomaterial applications.

PubMed

Oteyaka, Mustafa Ozgür; Unal, Hasan Hüseyin; Bilici, Namık; Taşçı, Eda

2013-01-01

The aim of this study was to define the chemical composition, morphology and crystallography of powdered fish heads of the species Argyrosomus regius for bone graft biomaterial applications. Two sizes of powder were prepared by different grinding methods; Powder A (coarse, d50=68.5 µm) and Powder B (fine, d50=19.1 µm). Samples were analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), thermogravimetry (TG), and energy dispersive X-ray spectroscopy (EDS). The powder was mainly composed of aragonite (CaCO3) and calcite (CaCO3). The XRD pattern of Powder A and B matched standard aragonite and calcite patterns. In addition, the calcium oxide (CaO) phase was found after the calcination of Powder A. Thermogravimetry analysis confirmed total mass losses of 43.6% and 47.3% in Powders A and B, respectively. The microstructure of Powder A was mainly composed of different sizes and tubular shape, whereas Powder B showed agglomerated particles. The high quantity of CaO and other oxides resemble the chemical composition of bone. In general, the powder can be considered as bone graft after transformation to hydroxyapatite phase.

Rapid formation of phase-clean 110 K (Bi-2223) powders derived via freeze-drying process

DOEpatents

Balachandran, Uthamalingam

1996-01-01

A process for the preparation of amorphous precursor powders for Pb-doped Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains.

Rapid formation of phase-clean 110 K (Bi-2223) powders derived via freeze-drying process

DOEpatents

Balachandran, U.

1996-06-04

A process for the preparation of amorphous precursor powders for Pb-doped Bi{sub 2}Sr{sub 2} Ca{sub 2}Cu{sub 3}O{sub x} (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains. 11 figs.

Critical current densities of powder-in-tube MgB2 tapes fabricated with nanometer-size Mg powder

NASA Astrophysics Data System (ADS)

Yamada, H.; Hirakawa, M.; Kumakura, H.; Matsumoto, A.; Kitaguchi, H.

2004-03-01

We fabricated powder-in-tube MgB2/Fe tapes using a powder mixture of nanometer-size Mg and commercial amorphous B and investigated the transport properties. High-purity nanometer-size Mg powder was fabricated by applying the thermal plasma method. 5-10 mol % SiC powder doping was tried to enhance the Jc properties. We found that the use of nanometer-size Mg powder was effective to increase the Jc values. The transport Jc values of the nondoped and 10 mol % SiC-doped tapes prepared with nanometer-size Mg powder reached 90 and 250 A/mm2 at 4.2 K and 10 T, respectively. These values were about five times higher than those of the tapes prepared with commercial Mg powder.

Single-step laser deposition of functionally graded coating by dual ‘wire powder’ or ‘powder powder’ feeding—A comparative study

NASA Astrophysics Data System (ADS)

Syed, Waheed Ul Haq; Pinkerton, Andrew J.; Liu, Zhu; Li, Lin

2007-07-01

The creation of iron-copper (Fe-Cu) alloys has practical application in improving the surface heat conduction and corrosion resistance of, for example, conformal cooling channels in steel moulds, but is difficult to achieve because the elements have got low inter-solubility and are prone to solidification cracking. Previous work by these authors has reported a method to produce a graded iron-nickel-copper coating in a single-step by direct diode laser deposition (DLD) of nickel wire and copper powder as a combined feedstock. This work investigates whether dual powder feeds can be used in that process to afford greater geometric flexibility and compares attributes of the 'nickel wire and copper powder' and 'nickel powder and copper powder' processes for deposition on a H13 tool steel substrate. In wire-powder deposition, a higher temperature developed in the melt pool causing a clad with a smooth gradient structure. The nickel powder in powder-powder deposition did not impart much heat into the melt pool so the melt pool solidified with sharp composition boundaries due to single metal melting in some parts. In wire-powder experiments, a graded structure was obtained by varying the flow rates of wire and powder. However, a graded structure was not realised in powder-powder experiments by varying either the feed or the directions. Reasons for the differences and flow patterns in the melt pools and their effect on final part properties of parts produced are discussed.

Effect of Powder Size and Shape on the SLS Processability and Mechanical Properties of a TPU Elastomer

NASA Astrophysics Data System (ADS)

Dadbakhsh, Sasan; Verbelen, Leander; Vandeputte, Tom; Strobbe, Dieter; Van Puyvelde, Peter; Kruth, Jean-Pierre

This work investigates the influence of powder size/shape on selective laser sintering (SLS) of a thermoplastic polyurethane (TPU) elastomer. It examines a TPU powder which had been cryogenically milled in two different sizes; coarse powder (D50∼200μm) with rough surfaces in comparison with a fine powder (D50∼63μm) with extremely fine flow additives. It is found that the coarse powder coalesces at lower temperatures and excessively smokes during the SLS processing. In comparison, the fine powder with flow additives is better processable at significantly higher powder bed temperatures, allowing a lower optimum laser energy input which minimizes smoking and degradation of the polymer. In terms of mechanical properties, good coalescence of both powders lead to parts with acceptable shear-punch strengths compared to injection molded parts. However, porosity and degradation from the optimum SLS parameters of the coarse powder drastically reduce the tensile properties to about one-third of the parts made from the fine powders as well as those made by injection molding (IM).

40 CFR 471.100 - Applicability; description of the powder metals subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... powder metals subcategory. 471.100 Section 471.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Metals Powders Subcategory § 471.100 Applicability; description of the powder metals...

40 CFR 471.100 - Applicability; description of the powder metals subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... powder metals subcategory. 471.100 Section 471.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Metals Powders Subcategory § 471.100 Applicability; description of the powder metals...

Improved camera for better X-ray powder photographs

NASA Technical Reports Server (NTRS)

Parrish, W.; Vajda, I. E.

1969-01-01

Camera obtains powder-type photographs of single crystals or polycrystalline powder specimens. X-ray diffraction photographs of a powder specimen are characterized by improved resolution and greater intensity. A reasonably good powder pattern of small samples can be produced for identification purposes.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, C.E.; Morrow, M.S.

1993-10-12

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, Cressie E.; Morrow, Marvin S.

1993-01-01

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Lead-free precussion primer mixes based on metastable interstitial composite (MIC) technology

DOEpatents

Dixon, George P.; Martin, Joe A.; Thompson, Don

1998-01-01

A lead-free percussion primer composition and a percussion cup containing e composition. The lead-free percussion primer composition is comprised of a mixture of about 45 wt % aluminum powder having an outer coating of aluminum oxide and molybdenum trioxide powder or a mixture of about 50 wt % aluminum powder having an outer coating of aluminum oxide and polytetrafluoroethylene powder. The aluminum powder, molybdenum trioxide powder and polytetrafluoroethylene powder has a particle size of 0.1 .mu.m or less, more preferably a particle size of from about 200-500 angstroms.

Does powdering of the dentition increase the accuracy of fusing 3D stereophotographs and digital dental casts.

PubMed

Rangel, Frits A; Chiu, Yu-Ting; Maal, Thomas J J; Bronkhorst, Ewald M; Bergé, Stefaan J; Kuijpers-Jagtman, Anne Marie

2016-08-01

The shiny vestibular surfaces of teeth make it difficult to match digital dental casts to 3D stereophotogrammetric images of patient teeth. This study tested whether reducing this shininess by coating the teeth with titanium-oxide powder might improve the accuracy of the matching procedure. Twenty patients participated in the study. For each patient, 3D stereophotogrammetric images were taken without and with a powder coating. Separately, digital dental casts were created. Next, the digital dental casts were fused with the 3D stereophotogrammetric images of either non-powdered or powdered dentition. Distance maps were created to evaluate the inter-surface distance between the digital dental cast and the 3D images. The matching accuracy was compared for dentition with and without powdering. Of all recorded distances between corresponding points, 95% was smaller than 0.84mm for the powdered dentition and smaller than 0.90mm for the non-powdered dentition. Although powdered dentition showed significantly better matching than non-powdered dentition, the difference was less than 0.1mm. Intra-observer statistics showed that five out of 24 repetitions gave significantly different results, but only for dentition that was not powdered. The patients did not have any major malocclusions. Severe malocclusions might cause greater difficulty in matching the dentition without powder. Only one type of powder was used, but it effectively reduced shininess. Powdering the dentition had a small, but significant, positive effect on matching. However, this effect was of minor clinical importance. Therefore, we do not recommend powdering the dentition for 3D stereophotogrammetric images used for matching procedures. © The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Research on Durability of Recycled Ceramic Powder Concrete

NASA Astrophysics Data System (ADS)

Chen, M. C.; Fang, W.; Xu, K. C.; Xie, L.

2017-06-01

Ceramic was ground into powder with 325 mesh and used to prepare for concrete. Basic mechanical properties, carbonation and chloride ion penetration of the concrete tests were conducted. In addition, 6-hour electric fluxes of recycled ceramic powder concrete were measured under loading. The results showed that the age strength of ceramics powder concrete is higher than that of the ordinary concrete and the fly ash concrete. The ceramic powder used as admixture would reduce the strength of concrete under no consideration of its impact factor; under consideration of the impact factor for ceramic powder as admixture, the carbonation resistance of ceramic powder concrete was significantly improved, and the 28 day carbonation depth of the ceramic powder concrete was only 31.5% of ordinary concrete. The anti-chloride-permeability of recycled ceramic powder concrete was excellent.

Determination of whey adulteration in milk powder by using laser induced breakdown spectroscopy.

PubMed

Bilge, Gonca; Sezer, Banu; Eseller, Kemal Efe; Berberoglu, Halil; Topcu, Ali; Boyaci, Ismail Hakki

2016-12-01

A rapid and in situ method has been developed to detect and quantify adulterated milk powder through adding whey powder by using laser induced breakdown spectroscopy (LIBS). The methodology is based on elemental composition differences between milk and whey products. Milk powder, sweet and acid whey powders were produced as standard samples, and milk powder was adulterated with whey powders. Based on LIBS spectra of standard samples and commercial products, species was identified using principle component analysis (PCA) method, and discrimination rate of milk and whey powders was found as 80.5%. Calibration curves were obtained with partial least squares regression (PLS). Correlation coefficient (R(2)) and limit of detection (LOD) values were 0.981 and 1.55% for adulteration with sweet whey powder, and 0.985 and 0.55% for adulteration with acid whey powder, respectively. The results were found to be consistent with the data from inductively coupled plasma - mass spectrometer (ICP-MS) method. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Studies on the brand traceability of milk powder based on NIR spectroscopy technology].

PubMed

Guan, Xiao; Gu, Fang-Qing; Liu, Jing; Yang, Yong-Jian

2013-10-01

Brand traceability of several different kinds of milk powder was studied by combining near infrared spectroscopy diffuse reflectance mode with soft independent modeling of class analogy (SIMCA) in the present paper. The near infrared spectrum of 138 samples, including 54 Guangming milk powder samples, 43 Netherlands samples, and 33 Nestle samples and 8 Yili samples, were collected. After pretreatment of full spectrum data variables in training set, principal component analysis was performed, and the contribution rate of the cumulative variance of the first three principal components was about 99.07%. Milk powder principal component regression model based on SIMCA was established, and used to classify the milk powder samples in prediction sets. The results showed that the recognition rate of Guangming milk powder, Netherlands milk powder and Nestle milk powder was 78%, 75% and 100%, the rejection rate was 100%, 87%, and 88%, respectively. Therefore, the near infrared spectroscopy combined with SIMCA model can classify milk powder with high accuracy, and is a promising identification method of milk powder variety.

Development of Biodegradable Polycation-Based Inhalable Dry Gene Powders by Spray Freeze Drying

PubMed Central

Okuda, Tomoyuki; Suzuki, Yumiko; Kobayashi, Yuko; Ishii, Takehiko; Uchida, Satoshi; Itaka, Keiji; Kataoka, Kazunori; Okamoto, Hirokazu

2015-01-01

In this study, two types of biodegradable polycation (PAsp(DET) homopolymer and PEG-PAsp(DET) copolymer) were applied as vectors for inhalable dry gene powders prepared by spray freeze drying (SFD). The prepared dry gene powders had spherical and porous structures with a 5~10-μm diameter, and the integrity of plasmid DNA could be maintained during powder production. Furthermore, it was clarified that PEG-PAsp(DET)-based dry gene powder could more sufficiently maintain both the physicochemical properties and in vitro gene transfection efficiencies of polyplexes reconstituted after powder production than PAsp(DET)-based dry gene powder. From an in vitro inhalation study using an Andersen cascade impactor, it was demonstrated that the addition of l-leucine could markedly improve the inhalation performance of dry powders prepared by SFD. Following pulmonary delivery to mice, both PAsp(DET)- and PEG-PAsp(DET)-based dry gene powders could achieve higher gene transfection efficiencies in the lungs compared with a chitosan-based dry gene powder previously reported by us. PMID:26343708

Mullite and Mullite/ZrO2-7wt.%Y2O3 Powders for Thermal Spraying of Environmental Barrier Coatings

NASA Astrophysics Data System (ADS)

Garcia, E.; Mesquita-Guimarães, J.; Miranzo, P.; Osendi, M. I.; Wang, Y.; Lima, R. S.; Moreau, C.

2010-01-01

Mullite and mullite/ZrO2-7wt.%Y2O3 coatings could be thought among the main protective layers for environment barrier coatings (EBCs) to protect Si-based substrates in future gas turbine engines. Considering that feedstock of the compound powder is not commercially available, two powder processing routes Spray Drying (SD) and Flame Spheroidization (FS) were implemented for both types of powders. For each method the particle size, the morphology, and microstructure of the powder particles was determined. In addition, the effect of the heat treatment on the powder crystallinity and microstructure of FS powders was also investigated. To evaluate their suitability as feedstock materials, the powders were plasma sprayed and their in-flight particle characteristics monitored for coatings production. The powder morphology was correlated to the in-flight particle characteristics and splat morphology to gain insight about into the influence of powder characteristics on the coating formation.

Consumer acceptance and aroma characterization of navy bean (Phaseolus vulgaris) powders prepared by extrusion and conventional processing methods.

PubMed

Szczygiel, Edward J; Harte, Janice B; Strasburg, Gale M; Cho, Sungeun

2017-09-01

Food products produced with bean ingredients are gaining in popularity among consumers due to the reported health benefits. Navy bean (Phaseolus vulgaris) powder produced through extrusion can be considered as a resource-efficient alternative to conventional methods, which often involve high water inputs. Therefore, navy bean powders produced with extrusion and conventional methods were assessed for the impact of processing on consumer liking in end-use products and odor-active compounds. Consumer acceptance results reveal significant differences in flavor, texture and overall acceptance scores of several products produced with navy bean powder. Crackers produced with extruded navy bean powder received higher hedonic flavor ratings than those produced with commercial navy bean powder (P < 0.001). GC-O data showed that the commercial powder produced through conventional processing had much greater contents of several aliphatic aldehydes commonly formed via lipid oxidation, such as hexanal, octanal and nonanal with descriptors of 'grassy', 'nutty', 'fruity', 'dusty', and 'cleaner', compared to the extruded powder. Extrusion processed navy bean powders were preferred over commercial powders for certain navy bean powder applications. This is best explained by substantial differences in aroma profiles of the two powders that may have been caused by lipid oxidation. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Effect of Powder-Suspended Dielectric on the EDM Characteristics of Inconel 625

NASA Astrophysics Data System (ADS)

Talla, Gangadharudu; Gangopadhyay, S.; Biswas, C. K.

2016-02-01

The current work attempts to establish the criteria for powder material selection by investigating the influence of various powder-suspended dielectrics and machining parameters on various EDM characteristics of Inconel 625 (a nickel-based super alloy) which is nowadays regularly used in aerospace, chemical, and marine industries. The powders include aluminum (Al), graphite, and silicon (Si) that have significant variation in their thermo-physical characteristics. Results showed that powder properties like electrical conductivity, thermal conductivity, density, and hardness play a significant role in changing the machining performance and the quality of the machined surface. Among the three powders, highest material removal rate was observed for graphite powder due to its high electrical and thermal conductivities. Best surface finish and least radial overcut (ROC) were attained using Si powder. Maximum microhardness was found for Si due to its low thermal conductivity and high hardness. It is followed by graphite and aluminum powders. Addition of powder to the dielectric has increased the crater diameter due to expansion of plasma channel. Powder-mixed EDM (PMEDM) was also effective in lowering the density of surface cracks with least number of cracks obtained with graphite powder. X-ray diffraction analysis indicated possible formation of metal carbides along with grain growth phenomenon of Inconel 625 after PMEDM.

Effects of red pepper powder on microbial communities and metabolites during kimchi fermentation.

PubMed

Jeong, Sang Hyeon; Lee, Hyo Jung; Jung, Ji Young; Lee, Se Hee; Seo, Hye-Young; Park, Wan-Soo; Jeon, Che Ok

2013-01-01

To investigate the effects of red pepper powder on kimchi fermentation, Baechu (Chinese cabbage) and Mu (radish) kimchi, with and without red pepper powder, were prepared and their characteristics, including pH, colony-forming units (CFU), microbial communities, and metabolites, were periodically monitored for 40days. Measurements of pH and CFU showed that the lag phases of kimchi fermentation were clearly extended by the addition of red pepper powder. Microbial community analysis using a barcoded pyrosequencing analysis showed that the bacterial diversities in kimchi with red pepper powder decreased more slowly than kimchi without red pepper powder as kimchi fermentation progressed. The kimchi microbial communities were represented mainly by the genera Leuconostoc and Lactobacillus in all kimchi, and the abundance of Weissella was negligible in kimchi without red pepper powder. However, interestingly, kimchi with red pepper powder contained much higher proportions of Weissella than kimchi without red pepper powder, while the proportions of Leuconostoc and Lactobacillus were evidently lower in kimchi with red pepper powder compared to kimchi without red pepper powder. Metabolite analysis using a (1)H NMR technique also showed that the fermentation of kimchi with red pepper powder progressed a little more slowly than that of kimchi without red pepper powder. Principle component analysis using microbial communities and metabolites supported the finding that the addition of red pepper powder into kimchi resulted in the slowing of the kimchi fermentation process, especially during the early fermentation period and influenced the microbial succession and metabolite production during the kimchi fermentation processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Resin-Powder Dispenser

NASA Technical Reports Server (NTRS)

Standfield, Clarence E.

1994-01-01

Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

Glove powder's carrying capacity for latex protein: analysis using the ASTM ELISA test.

PubMed

Beezhold, D; Horton, K; Hickey, V; Daddona, J; Kostyal, D

2003-01-01

Glove donning powders carry latex proteins and disperse them into the workplace environment. We have used the ASTM D6499 ELISA to quantify the amount of latex antigen bound to and carried by glove powders. We could differentiate between a small amount of protein actually bound to the powders and a larger amount carried by the powder. Enhanced binding of a major allergen, Hev b 5, to the starch powders was demonstrated by Western blot. The D6499 ELISA is able to measure total latex antigen, soluble and powder bound, simultaneously without the need to centrifuge the samples.

Data on the influence of cold isostatic pre-compaction on mechanical properties of polycrystalline nickel sintered using Spark Plasma Sintering.

PubMed

Dutel, Guy-Daniel; Langlois, Patrick; Tingaud, David; Vrel, Dominique; Dirras, Guy

2017-04-01

Data regarding bulk polycrystalline nickel samples obtained by powder metallurgy using Spark Plasma Sintering (SPS) are presented, with a special emphasis on the influence of a cold isostatic pre-compaction on the resulting morphologies and subsequent mechanical properties. Three types of initial powders are used, nanometric powders, micrometric powders and a mixture of the formers. For each type of powder, the SPS cycle has been optimized for the powders without pre-compaction and the same cycle has been used to also sinter pre-compacted powders.

Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2016-05-03

A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Laminated composite of magnetic alloy powder and ceramic powder and process for making same

DOEpatents

Moorhead, Arthur J.; Kim, Hyoun-Ee

1999-01-01

A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are discosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder.

Laminated composite of magnetic alloy powder and ceramic powder and process for making same

DOEpatents

Moorhead, A.J.; Kim, H.

1999-08-10

A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are disclosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder. 9 figs.

Effects of extrusion cooking on the chemical composition and functional properties of dry common bean powders.

PubMed

Ai, Yongfeng; Cichy, Karen A; Harte, Janice B; Kelly, James D; Ng, Perry K W

2016-11-15

The impact of extrusion cooking on the chemical composition and functional properties of bean powders from four common bean varieties was investigated. The raw bean powders were extruded under eight different conditions, and the extrudates were then dried and ground (particle size⩽0.5mm). Compared with corresponding non-extruded (raw) bean powders (particle size⩽0.5mm), the extrusion treatments did not substantially change the protein and starch contents of the bean powders and showed inconsistent effects on the sucrose, raffinose and stachyose contents. The extrusion cooking did cause complete starch gelatinization and protein denaturation of the bean powders and thus changed their pasting properties and solvent-retention capacities. The starch digestibilities of the cooked non-extruded and cooked extruded bean powders were comparable. The extruded bean powders displayed functional properties similar to those of two commercial bean powders. Copyright © 2016 Elsevier Ltd. All rights reserved.

An analysis of un-dissolved powders of instant powdered soup by using ultrasonographic image

NASA Astrophysics Data System (ADS)

Kawaai, Yukinori; Kato, Kunihito; Yamamoto, Kazuhiko; Kasamatsu, Chinatsu

2008-11-01

Nowadays, there are many instant powdered soups around us. When we make instant powdered soup, sometimes we cannot dissolve powders perfectly. Food manufacturers want to improve this problem in order to make better products. Therefore, they have to measure the state and volume of un-dissolved powders. Earlier methods for analyzing removed the un-dissolved powders from the container, the state of the un-dissolved power was changed. Our research using ultrasonographic image can measure the state of un-dissolved powders with no change by taking cross sections of the soup. We then make 3D soup model from these cross sections of soup. Therefore we can observe the inside of soup that we do not have ever seen. We construct accurate 3D model. We can visualize the state and volume of un-dissolved powders with analyzing the 3D soup models.

Effect of incorporation of pumpkin (Cucurbita moshchata) powder and guar gum on the rheological properties of wheat flour.

PubMed

Kundu, Himani; Grewal, Raj Bala; Goyal, Ankit; Upadhyay, Neelam; Prakash, Saurabh

2014-10-01

The present study was carried out to study the effect of incorporation of fibre rich pumpkin powder and guar gum on the farinographic characteristics of wheat flour. The flour and pumpkin powder were assessed for proximate composition, total dietary fibre, minerals and β-carotene. Pumpkin powder contained appreciable amount of fibre, minerals and β-carotene. The effects of incorporation of different levels of pumpkin powder and guar gum along with pumpkin powder on farinographic characteristics were studied. Dough development time, dough stability, time to break down and farinograph quality number increased whereas mixing tolerance index decreased with incorporation of pumpkin powder (> 5 %) and guar gum (1.0 and 1.5 %) along with pumpkin powder in the flour. Resistance to extension as well as extensibility of dough prepared increased significantly by adding pumpkin powder (5-15 %) whereas increase in resistance to extension only was noticed with inclusion of guar gum (0.5-1.5 %) to flour containing 5 % pumpkin powder. Results indicated that pumpkin can be processed to powder that can be utilized with guar gum for value addition.

Influence of combinations of fenugreek, garlic, and black pepper powder on production traits of the broilers.

PubMed

Kirubakaran, A; Moorthy, M; Chitra, R; Prabakar, G

2016-05-01

To study the effects of combinations of fenugreek (Trigonella foenum-graecum L.), garlic (Allium sativum), and black pepper (Piper nigrum) powder supplementation on production traits of broiler chickens. A total of 288 commercial broiler chicks were randomly assigned to 1-9 groups with 4 replicates each. An experiment was conducted in broilers with different feed formulations; control feed, with no added fenugreek, garlic, and black pepper powder; and 8 treatment groups receiving feed supplemented with different combinations of fenugreek, garlic, and black pepper powder. The individual broilers' body weight and feed consumption were recorded and calculate the body weight gain and feed conversion ratio (FCR). Broiler's weight gain and FCR were significantly higher in groups receiving feed supplemented with garlic and black pepper powder combinations (p<0.01). Cumulative feed consumption was significantly higher in groups receiving feed supplemented with garlic and black pepper powder combinations (p<0.01). The combination of garlic and black pepper powder supplemented broiler feed fed groups showed higher production performance. The 5 g/kg garlic powder+1 g/kg black pepper powder and 10 g/kg garlic powder+2 g/kg black pepper powder significantly improved the weight gain and FCR.

Comparative study of particle structure evolution during water sorption: skim and whole milk powders.

PubMed

Murrieta-Pazos, I; Gaiani, C; Galet, L; Cuq, B; Desobry, S; Scher, J

2011-10-01

Surface composition of dairy powders influences significantly a quantity of functional properties such as rehydration, caking, agglomeration. Nevertheless, the kinetic of water uptake by the powders was never directly related to the structure and the composition of the surface. In this work, the effect of relative humidity on the structural reorganization of two types of dairy powder was studied. The water-powder interaction for industrial whole milk powder, and skim milk powder was studied using dynamic vapor sorption. The water sorption isotherms were fitted with a Brunner-Emmet-Teller model and each stage of the sorption curve was analyzed with a Fickian diffusion. The water content in the monolayer predicted for each powder and the moisture diffusivity calculated were discussed and compared. Concurrently, powders microstructure and powders surface under variable relative humidity were assessed by X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray and atomic force microscopy. A correlation between the data obtained from the sorption isotherms and the modifications of structure allowed us to conclude that powder microstructure and chemical state of the components could play an important role in determining the water diffusivity. Copyright © 2011 Elsevier B.V. All rights reserved.

The Application of Globular Water-Atomized Iron Powders for Additive Manufacturing by a LENS Technique.

PubMed

Durejko, Tomasz; Aniszewska, Justyna; Ziętala, Michał; Antolak-Dudka, Anna; Czujko, Tomasz; Varin, Robert A; Paserin, Vlad

2018-05-18

The water-atomized ATOMET 28, 1001, 4701, and 4801 powders, manufactured by Rio Tinto Metal Powders, were used for additive manufacturing by a laser engineered net shaping (LENS) technique. Their overall morphology was globular and rounded with a size distribution from about 20 to 200 µm. Only the ATOMET 28 powder was characterized by a strong inhomogeneity of particle size and irregular polyhedral shape of powder particles with sharp edges. The powders were pre-sieved to a size distribution from 40 to 150 µm before LENS processing. One particular sample-LENS-fabricated from the ATOMET 28 powder-was characterized by the largest cross-sectional (2D) porosity of 4.2% and bulk porosity of 3.9%, the latter determined by microtomography measurements. In contrast, the cross-sectional porosities of bulk, solid, nearly cubic LENS-fabricated samples from the other ATOMET powders exhibited very low porosities within the range 0.03⁻0.1%. Unexpectedly, the solid sample-LENS-fabricated from the reference, a purely spherical Fe 99.8 powder-exhibited a porosity of 1.1%, the second largest after that of the pre-sieved, nonspherical ATOMET 28 powder. Vibrations incorporated mechanically into the LENS powder feeding system substantially improved the flow rate vs. feeding rate dependence, making it completely linear with an excellent coefficient of fit, R² = 0.99. In comparison, the reference powder Fe 99.8 always exhibited a linear dependence of the powder flow rate vs. feeding rate, regardless of vibrations.

Enhanced centrifuge-based approach to powder characterization

NASA Astrophysics Data System (ADS)

Thomas, Myles Calvin

Many types of manufacturing processes involve powders and are affected by powder behavior. It is highly desirable to implement tools that allow the behavior of bulk powder to be predicted based on the behavior of only small quantities of powder. Such descriptions can enable engineers to significantly improve the performance of powder processing and formulation steps. In this work, an enhancement of the centrifuge technique is proposed as a means of powder characterization. This enhanced method uses specially designed substrates with hemispherical indentations within the centrifuge. The method was tested using simulations of the momentum balance at the substrate surface. Initial simulations were performed with an ideal powder containing smooth, spherical particles distributed on substrates designed with indentations. The van der Waals adhesion between the powder, whose size distribution was based on an experimentally-determined distribution from a commercial silica powder, and the indentations was calculated and compared to the removal force created in the centrifuge. This provided a way to relate the powder size distribution to the rotational speed required for particle removal for various indentation sizes. Due to the distinct form of the data from these simulations, the cumulative size distribution of the powder and the Hamaker constant for the system were be extracted. After establishing adhesion force characterization for an ideal powder, the same proof-of-concept procedure was followed for a more realistic system with a simulated rough powder modeled as spheres with sinusoidal protrusions and intrusions around the surface. From these simulations, it was discovered that an equivalent powder of smooth spherical particles could be used to describe the adhesion behavior of the rough spherical powder by establishing a size-dependent 'effective' Hamaker constant distribution. This development made it possible to describe the surface roughness effects of the entire powder through one adjustable parameter that was linked to the size distribution. It is important to note that when the engineered substrates (hemispherical indentations) were applied, it was possible to extract both powder size distribution and effective Hamaker constant information from the simulated centrifuge adhesion experiments. Experimental validation of the simulated technique was performed with a silica powder dispersed onto a stainless steel substrate with no engineered surface features. Though the proof-of-concept work was accomplished for indented substrates, non-ideal, relatively flat (non-indented) substrates were used experimentally to demonstrate that the technique can be extended to this case. The experimental data was then used within the newly developed simulation procedure to show its application to real systems. In the absence of engineered features on the substrates, it was necessary to specify the size distribution of the powder as an input to the simulator. With this information, it was possible to extract an effective Hamaker constant distribution and when the effective Hamaker constant distribution was applied in conjunction with the size distribution, the observed adhesion force distribution was described precisely. An equation was developed that related the normalized effective Hamaker constants (normalized by the particle diameter) to the particle diameter was formulated from the effective Hamaker constant distribution. It was shown, by application of the equation, that the adhesion behavior of an ideal (smooth, spherical) powder with an experimentally-validated, effective Hamaker constant distribution could be used to effectively represent that of a realistic powder. Thus, the roughness effects and size variations of a real powder are captured in this one distributed parameter (effective Hamaker constant distribution) which provides a substantial improvement to the existing technique. This can lead to better optimization of powder processing by enhancing powder behavior models.

Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products

PubMed Central

2017-01-01

This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (−) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed (p<0.05) in the negative control samples, whereas the cooking loss in samples with natural calcium powder added was similar (p>0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher (p<0.05) in samples containing natural calcium powder (treatments 1, 2, 3, and 4) than in the positive control. The combination of oyster shell calcium powder and egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities. PMID:28943770

Roller compaction of moist pharmaceutical powders.

PubMed

Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

2010-05-31

The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Printability of calcium phosphate: calcium sulfate powders for the application of tissue engineered bone scaffolds using the 3D printing technique.

PubMed

Zhou, Zuoxin; Buchanan, Fraser; Mitchell, Christina; Dunne, Nicholas

2014-05-01

In this study, calcium phosphate (CaP) powders were blended with a three-dimensional printing (3DP) calcium sulfate (CaSO4)-based powder and the resulting composite powders were printed with a water-based binder using the 3DP technology. Application of a water-based binder ensured the manufacture of CaP:CaSO4 constructs on a reliable and repeatable basis, without long term damage of the printhead. Printability of CaP:CaSO4 powders was quantitatively assessed by investigating the key 3DP process parameters, i.e. in-process powder bed packing, drop penetration behavior and the quality of printed solid constructs. Effects of particle size, CaP:CaSO4 ratio and CaP powder type on the 3DP process were considered. The drop penetration technique was used to reliably identify powder formulations that could be potentially used for the application of tissue engineered bone scaffolds using the 3DP technique. Significant improvements (p<0.05) in the 3DP process parameters were found for CaP (30-110 μm):CaSO4 powders compared to CaP (<20 μm):CaSO4 powders. Higher compressive strength was obtained for the powders with the higher CaP:CaSO4 ratio. Hydroxyapatite (HA):CaSO4 powders showed better results than beta-tricalcium phosphate (β-TCP):CaSO4 powders. Solid and porous constructs were manufactured using the 3DP technique from the optimized CaP:CaSO4 powder formulations. High-quality printed constructs were manufactured, which exhibited appropriate green compressive strength and a high level of printing accuracy. Copyright © 2014 Elsevier B.V. All rights reserved.

Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products.

PubMed

Cho, Min Guk; Bae, Su Min; Jeong, Jong Youn

2017-01-01

This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (-) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed ( p <0.05) in the negative control samples, whereas the cooking loss in samples with natural calcium powder added was similar ( p >0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher ( p <0.05) in samples containing natural calcium powder (treatments 1, 2, 3, and 4) than in the positive control. The combination of oyster shell calcium powder and egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities.

Slip casting nano-particle powders for making transparent ceramics

DOEpatents

Kuntz, Joshua D [Livermore, CA; Soules, Thomas F [Livermore, CA; Landingham, Richard Lee [Livermore, CA; Hollingsworth, Joel P [Oakland, CA

2011-04-12

A method of making a transparent ceramic including the steps of providing nano-ceramic powders in a processed or unprocessed form, mixing the powders with de-ionized water, the step of mixing the powders with de-ionized water producing a slurry, sonifing the slurry to completely wet the powder and suspend the powder in the de-ionized water, separating very fine particles from the slurry, molding the slurry, and curing the slurry to produce the transparent ceramic.

System Applies Polymer Powder To Filament Tow

NASA Technical Reports Server (NTRS)

Baucom, Robert M.; Snoha, John J.; Marchello, Joseph M.

1993-01-01

Polymer powder applied uniformly and in continuous manner. Powder-coating system applies dry polymer powder to continuous fiber tow. Unique filament-spreading technique, combined with precise control of tension on fibers in system, ensures uniform application of polymer powder to web of spread filaments. Fiber tows impregnated with dry polymer powders ("towpregs") produced for preform-weaving and composite-material-molding applications. System and process valuable to prepreg industry, for production of flexible filament-windable tows and high-temperature polymer prepregs.

Investigation of the Dependences of the Attenuation Properties of Cryogenic Metal-Powder Filters on the Preparation Method

NASA Astrophysics Data System (ADS)

Lee, Sung Hoon; Lee, Soon-Gul

2018-04-01

We fabricated low-pass metal powder filters for use in low-noise measurements at cryogenic temperatures and investigated their attenuation characteristics for different wire-turn densities, metalpowder shapes, and preparation methods at frequencies up to 20 GHz. We used nominally 30-μmsized stainless-steel 304L powder and mixed it with low-temperature binders. The low-temperature binders used were Stycast 2850FT (Emerson and Cumming) with catalyst 23LV and GE-7031 varnish. A 0.1-mm insulated copper wire was wound on preformed powder-mixture bobbins in the shape of a circular rod and was encapsulated in metal tubes with the powder mixture. All the fabricated powder filters showed a large attenuation at high frequencies with a cut-off frequency near 1 GHz. For filters of the same wire length, a lower wiring density showed a larger attenuation, which implies that the amount of powder in close contact with the wire determines the attenuation. Filters made of a powder/varnish mixture showed significantly larger attenuations than those of a powder/stycast mixture, and the attenuation improved with increasing powder ratio in the mixture. The low-temperature thermal conductivities of a 2 : 1 powder/Stycast mixture and a 5 : 1 powder/varnish mixture showed similar values at temperatures up to 4.2 K.

Comparison of blueberry powder produced via foam-mat freeze-drying versus spray-drying: evaluation of foam and powder properties.

PubMed

Darniadi, Sandi; Ho, Peter; Murray, Brent S

2018-03-01

Blueberry juice powder was developed via foam-mat freeze-drying (FMFD) and spray-drying (SD) via addition of maltodextrin (MD) and whey protein isolate (WPI) at weight ratios of MD/WPI = 0.4 to 3.2 (with a fixed solids content of 5 wt% for FMFD and 10 wt% for SD). Feed rates of 180 and 360 mL h -1 were tested in SD. The objective was to evaluate the effect of the drying methods and carrier agents on the physical properties of the corresponding blueberry powders and reconstituted products. Ratios of MD/WPI = 0.4, 1.0 and 1.6 produced highly stable foams most suitable for FMFD. FMFD gave high yields and low bulk density powders with flake-like particles of large size that were also dark purple with high red values. SD gave low powder recoveries. The powders had higher bulk density and faster rehydration times, consisting of smooth, spherical and smaller particles than in FMFD powders. The SD powders were bright purple but less red than FMFD powders. Solubility was greater than 95% for both FMFD and SD powders. The FMFD method is a feasible method of producing blueberry juice powder and gives products retaining more characteristics of the original juice than SD. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

30 CFR 75.1101-22 - Inspection of dry powder chemical systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Inspection of dry powder chemical systems. 75...-22 Inspection of dry powder chemical systems. (a) Each dry powder chemical system shall be examined... the dry powder chemical system has been actuated, all components of the system shall be cleaned...

30 CFR 75.1101-22 - Inspection of dry powder chemical systems.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Inspection of dry powder chemical systems. 75...-22 Inspection of dry powder chemical systems. (a) Each dry powder chemical system shall be examined... the dry powder chemical system has been actuated, all components of the system shall be cleaned...

Composite material dosimeters

DOEpatents

Miller, Steven D.

1996-01-01

The present invention is a composite material containing a mix of dosimeter material powder and a polymer powder wherein the polymer is transparent to the photon emission of the dosimeter material powder. By mixing dosimeter material powder with polymer powder, less dosimeter material is needed compared to a monolithic dosimeter material chip. Interrogation is done with excitation by visible light.

30 CFR 75.1101-22 - Inspection of dry powder chemical systems.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Inspection of dry powder chemical systems. 75...-22 Inspection of dry powder chemical systems. (a) Each dry powder chemical system shall be examined... the dry powder chemical system has been actuated, all components of the system shall be cleaned...

30 CFR 75.1101-22 - Inspection of dry powder chemical systems.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Inspection of dry powder chemical systems. 75...-22 Inspection of dry powder chemical systems. (a) Each dry powder chemical system shall be examined... the dry powder chemical system has been actuated, all components of the system shall be cleaned...

30 CFR 75.1101-14 - Installation of dry powder chemical systems.

Code of Federal Regulations, 2014 CFR

2014-07-01

...' Laboratories, Inc., or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Installation of dry powder chemical systems. 75...-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall...

30 CFR 75.1101-14 - Installation of dry powder chemical systems.

Code of Federal Regulations, 2012 CFR

2012-07-01

...' Laboratories, Inc., or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Installation of dry powder chemical systems. 75...-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall...

30 CFR 75.1101-14 - Installation of dry powder chemical systems.

Code of Federal Regulations, 2011 CFR

2011-07-01

...' Laboratories, Inc., or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Installation of dry powder chemical systems. 75...-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall...

30 CFR 75.1101-14 - Installation of dry powder chemical systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

...' Laboratories, Inc., or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Installation of dry powder chemical systems. 75...-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall...

30 CFR 75.1101-14 - Installation of dry powder chemical systems.

Code of Federal Regulations, 2013 CFR

2013-07-01

...' Laboratories, Inc., or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Installation of dry powder chemical systems. 75...-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall...

30 CFR 57.6901 - Black powder.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a... dimension stone. (b) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed...

30 CFR 56.6901 - Black powder.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Black powder. 56.6901 Section 56.6901 Mineral....6901 Black powder. (a) Black powder shall be used for blasting only when a desired result cannot be...) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed cargo space while being...

30 CFR 56.6901 - Black powder.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Black powder. 56.6901 Section 56.6901 Mineral....6901 Black powder. (a) Black powder shall be used for blasting only when a desired result cannot be...) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed cargo space while being...

30 CFR 57.6901 - Black powder.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a... dimension stone. (b) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed...

30 CFR 57.6901 - Black powder.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a... dimension stone. (b) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed...

30 CFR 57.6901 - Black powder.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a... dimension stone. (b) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed...

30 CFR 56.6901 - Black powder.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Black powder. 56.6901 Section 56.6901 Mineral....6901 Black powder. (a) Black powder shall be used for blasting only when a desired result cannot be...) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed cargo space while being...

30 CFR 57.6901 - Black powder.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a... dimension stone. (b) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed...

30 CFR 56.6901 - Black powder.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Black powder. 56.6901 Section 56.6901 Mineral....6901 Black powder. (a) Black powder shall be used for blasting only when a desired result cannot be...) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed cargo space while being...

30 CFR 56.6901 - Black powder.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Black powder. 56.6901 Section 56.6901 Mineral....6901 Black powder. (a) Black powder shall be used for blasting only when a desired result cannot be...) Containers of black powder shall be— (1) Nonsparking; (2) Kept in a totally enclosed cargo space while being...

21 CFR 169.182 - Vanilla-vanillin powder.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Vanilla-vanillin powder. 169.182 Section 169.182... Dressings and Flavorings § 169.182 Vanilla-vanillin powder. (a) Vanilla-vanillin powder conforms to the... prescribed for vanilla powder by § 169.179, except that for each unit of vanilla constituent as defined in...

21 CFR 169.182 - Vanilla-vanillin powder.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Vanilla-vanillin powder. 169.182 Section 169.182... Dressings and Flavorings § 169.182 Vanilla-vanillin powder. (a) Vanilla-vanillin powder conforms to the... prescribed for vanilla powder by § 169.179, except that for each unit of vanilla constituent as defined in...

21 CFR 169.182 - Vanilla-vanillin powder.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Vanilla-vanillin powder. 169.182 Section 169.182... Dressings and Flavorings § 169.182 Vanilla-vanillin powder. (a) Vanilla-vanillin powder conforms to the... prescribed for vanilla powder by § 169.179, except that for each unit of vanilla constituent as defined in...

21 CFR 169.182 - Vanilla-vanillin powder.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Vanilla-vanillin powder. 169.182 Section 169.182... Dressings and Flavorings § 169.182 Vanilla-vanillin powder. (a) Vanilla-vanillin powder conforms to the... prescribed for vanilla powder by § 169.179, except that for each unit of vanilla constituent as defined in...

21 CFR 169.182 - Vanilla-vanillin powder.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Vanilla-vanillin powder. 169.182 Section 169.182... Dressings and Flavorings § 169.182 Vanilla-vanillin powder. (a) Vanilla-vanillin powder conforms to the... prescribed for vanilla powder by § 169.179, except that for each unit of vanilla constituent as defined in...

Microstructure of rapidly solidified Nb-based pre-alloyed powders for additive manufacturing

NASA Astrophysics Data System (ADS)

Guo, Yueling; Jia, Lina; Kong, Bin; Zhang, Shengnan; Zhang, Fengxiang; Zhang, Hu

2017-07-01

For powder-based additive manufacturing, sphere-shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by plasma rotating electrode processing (PREP). The microstructure, surface oxidation and microhardness of the pre-alloyed powders were systematically investigated. Results showed that the main phases were Nb solid solution (Nbss) and Cr2Nb. The Cr2Nb phases were further determined using transmission electron microscopy (TEM). Fine dendrite structures were observed in the as-fabricated pre-alloyed powders, which transformed to large grains after heat treatment (HT) at 1450 °C for 3 h. With the increase of powder size, the secondary dendrite arm spacing (SDAS) increased and the microhardness (HV) decreased. A clean powder surface free of oxide particles was obtained by PREP and an oxide layer with 9.39 nm in thickness was generated on the powder surface. Compared with Cr- and Nb-oxides, more Ti-oxides were formed on outmost powder surface with a higher content of Ti (up to 47.86 at.%). The differences upon the microstructure and microhardness of the pre-alloyed powders with different sizes were discussed.

To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

PubMed

Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

2017-05-01

Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

Heat Treatment of Gas-Atomized Powders for Cold Spray Deposition

NASA Astrophysics Data System (ADS)

Story, William A.; Brewer, Luke N.

2018-02-01

This communication demonstrates the efficacy of heat treatment on the improved deposition characteristics of aluminum alloy powders. A novel furnace was constructed for solutionizing of feedstock powders in an inert atmosphere while avoiding sintering. This furnace design achieved sufficiently high cooling rates to limit re-precipitation during powder cooling. Microscopy showed homogenization of the powder particle microstructures after heat treatment. Cold spray deposition efficiency with heat-treated powders substantially increased for the alloys AA2024, AA6061, and AA7075.

[Advances in studies on bear bile powder].

PubMed

Zhou, Chao-fan; Gao, Guo-jian; Liu, Ying

2015-04-01

In this paper, a detailed analysis was made on relevant literatures about bear bile powder in terms of chemical component, pharmacological effect and clinical efficacy, indicating bear bile powder's significant pharmacological effects and clinical application in treating various diseases. Due to the complex composition, bear bile powder is relatively toxic. Therefore, efforts shall be made to study bear bile powder's pharmacological effects, clinical application, chemical composition and toxic side-effects, with the aim to provide a scientific basis for widespread reasonable clinical application of bear bile powder.

FGM (Functionally Graded Material) Thermal Barrier Coatings for Hypersonic Structures - Design and Thermal Structural Analysis

DTIC Science & Technology

2007-06-29

than others. It was found that TZ-3Y-E, which is a partially stabilised zirconia powder , was particularly suitable. The percentage of ceramic powder...layered coatings The current ceramic powder that was being used was a fully stabilised zirconia powder TZ-0Y. However a readily available powder...TZ-3Y-E, partially stabilised zirconia powder , was available and utilised. These tests consisted of a combination of 3, 4 and 5 layers. In the

Minimum ignition temperature of nano and micro Ti powder clouds in the presence of inert nano TiO2 powder.

PubMed

Yuan, Chunmiao; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

2014-06-30

Minimum ignition temperature (MIT) of micro Ti powder increased gradually with increases in nano-sized TiO2 employed as an inertant. Solid TiO2 inertant significantly reduced ignition hazard of micro Ti powder in contact with hot surfaces. The MIT of nano Ti powder remained low (583 K), however, even with 90% TiO2. The MIT of micro Ti powder, when mixed with nano Ti powder at concentrations as low as 10%, decreased so dramatically that its application as a solid fuel may be possible. A simple MIT model was proposed for aggregate particle size estimation and better understanding of the inerting effect of nano TiO2 on MIT. Estimated particle size was 1.46-1.51 μm larger than that in the 20-L sphere due to poor dispersion in the BAM oven. Calculated MITs were lower than corresponding empirically determined values for micro Ti powder because nano-sized TiO2 coated the micro Ti powder, thereby decreasing its reaction kinetics. In the case of nano Ti powder, nano-sized TiO2 facilitated dispersion of nano Ti powder which resulted in a calculated MIT that was greater than the experimentally determined value. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of the highly dispersed powder of titanium carbonitride by SHS azide technology with previous partial nitriding

NASA Astrophysics Data System (ADS)

Amosov, A. P.; Markov, Yu M.; Dobrovolskaya, R. A.; Nikolaeva, E. N.

2017-02-01

It is shown that the powder of very hard refractory titanium carbonitride (TiC0.5N0.5) is the basis of tungsten-free hard alloys which are prospective for application as inexpensive cutting tools. The finer the powder of titanium carbonitrideis, the moreenhanced properties of hard alloys, sintered from the powder, are. An opportunity to reduce the particle size of the titanium carbonitride powder obtained by energy-saving azide technology of self-propagating high-temperature synthesis at the cost of reducing the particle size of the initial titanium powderwas investigated. To ensure the safety of the grinding process of the initial metal titanium powder, it was offered to nitride a Ti powder partially into a TiN0.2 compound. Such partial nitriding was performed by the azidetechnology with lack of sodium azide (NaN3) as a nitriding reagent. After intensive grinding in the planetary ball mill, the TiN0.2 powder turned into a superfine powder with an ultrafine structure. This powder was capable of nitriding and carburizing in the azide technology with formation of superfine pure powder agglomerates which are composed of ultrafine and nano-particles of TiC0.5N0.5.

Influence of combinations of fenugreek, garlic, and black pepper powder on production traits of the broilers

PubMed Central

Kirubakaran, A.; Moorthy, M.; Chitra, R.; Prabakar, G.

2016-01-01

Aim: To study the effects of combinations of fenugreek (Trigonella foenum-graecum L.), garlic (Allium sativum), and black pepper (Piper nigrum) powder supplementation on production traits of broiler chickens. Materials and Methods: A total of 288 commercial broiler chicks were randomly assigned to 1-9 groups with 4 replicates each. An experiment was conducted in broilers with different feed formulations; control feed, with no added fenugreek, garlic, and black pepper powder; and 8 treatment groups receiving feed supplemented with different combinations of fenugreek, garlic, and black pepper powder. The individual broilers’ body weight and feed consumption were recorded and calculate the body weight gain and feed conversion ratio (FCR). Results: Broiler’s weight gain and FCR were significantly higher in groups receiving feed supplemented with garlic and black pepper powder combinations (p<0.01). Cumulative feed consumption was significantly higher in groups receiving feed supplemented with garlic and black pepper powder combinations (p<0.01). Conclusion: The combination of garlic and black pepper powder supplemented broiler feed fed groups showed higher production performance. The 5 g/kg garlic powder+1 g/kg black pepper powder and 10 g/kg garlic powder+2 g/kg black pepper powder significantly improved the weight gain and FCR. PMID:27284222

Minimum ignition energy of nano and micro Ti powder in the presence of inert nano TiO₂ powder.

PubMed

Chunmiao, Yuan; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

2014-06-15

The inerting effect of nano-sized TiO2 powder on ignition sensitivity of nano and micro Ti powders was investigated with a Mike 3 apparatus. "A little is not good enough" is also suitable for micro Ti powders mixed with nano-sized solid inertants. MIE of the mixtures did not significantly increase until the TiO2 percentage exceeded 50%. Nano-sized TiO2 powders were ineffective as an inertant when mixed with nano Ti powders, especially at higher dust loadings. Even with 90% nano TiO2 powder, mixtures still showed high ignition sensitivity because the statistic energy was as low as 2.1 mJ. Layer fires induced by ignited but unburned metal particles may occur for micro Ti powders mixed with nano TiO2 powders following a low level dust explosion. Such layer fires could lead to a violent dust explosion after a second dispersion. Thus, additional attention is needed to prevent metallic layer fires even where electric spark potential is low. In the case of nano Ti powder, no layer fires were observed because of less flammable material involved in the mixtures investigated, and faster flame propagation in nanoparticle clouds. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of acid-modified Imperata cylindrica powder for latent fingerprint development.

PubMed

Low, Wei Zeng; Khoo, Bee Ee; Aziz, Zalina Binti Abdul; Low, Ling Wei; Teng, Tjoon Tow; bin Abdullah, Ahmad Fahmi Lim

2015-09-01

A novel powdering material that utilizes acid-modified Imperata cylindrica (IC) powder for the development of fingermarks was studied. Experiments were carried out to determine the suitability, adherence quality and sensitivity of the acid-modified IC powder. Fingermarks of different constituents (eccrine, sebaceous and natural fingermarks) on different types of surfaces were used. Acid-modified IC powder was also used to develop fingermarks of different ages as well as aged fingermarks recovered from the water. From the visual inspection, acid-modified IC powder was able to interact with different fingermark constituents and produced distinct ridge details on the examined surfaces. It was also able to develop aged fingermarks and fingermarks that were submerged in water. A statistical comparison was made against the Sirchie® Hi-Fi black powder in terms of the powders' sensitivity and quality of the developed natural fingermarks. The image quality was analyzed using MITRE's Image Quality of Fingerprint (IQF) software. From the experiments, acid-modified IC powder has the potential as a fingermark development powder, although natural fingermarks developed by Sirchie® black powder showed better quality and sensitivity based on the results of the statistical comparison. Copyright © 2015 The Chartered Society of Forensic Sciences. Published by Elsevier Ireland Ltd. All rights reserved.

Nasal deposition and clearance in man: comparison of a bidirectional powder device and a traditional liquid spray pump.

PubMed

Djupesland, Per Gisle; Skretting, Arne

2012-10-01

Delivery of powder formulations to the nose is an attractive alternative for many drugs and vaccines. This study compared the regional nasal deposition and clearance patterns of lactose powder delivered by the OptiNose powder device (Opt-Powder; OptiNose US Inc., Yardley, PA, USA) to that of liquid aerosol administered via a traditional hand-actuated liquid spray pump (Rexam SP270, Rexam Pharma, France). The study was an open-label, crossover design in seven healthy subjects (five females, two males). The regional nasal deposition and clearance patterns of the Opt-Powder device were compared to a traditional liquid spray pump by dynamic gamma camera imaging after administration of either (99m)Tc-labeled lactose powder or liquid (99m)Tc- diethelyne triamine pentaacetic acid-aerosol. The gamma camera images were scaled and aligned with sagittal magnetic resonance images to identify nasal regions. Possible deposition of radiolabeled material in the lungs following both methods of delivery was also evaluated. Both powder and spray were distributed to all of the nasal regions. The Opt-Powder device, however, achieved significantly larger initial deposition in the upper and middle posterior regions of the nose than spray (upper posterior region; Opt-Powder 18.3% ± 11.5 vs. Spray 2.4% ± 1.8, p<0.02; sum of upper and middle posterior regions; Opt-Powder 53.5% ± 18.5 vs. Spray 15.7% ± 13.8, p<0.02). The summed initial deposition to the lower anterior and posterior regions for spray was three times higher compared to Opt-Powder (Opt-Powder 17.4% ± 24.5 vs. Spray 59.4% ± 18.2, p<0.04). OptiNose powder delivery resulted in more rapid overall nasal clearance. No lung deposition was observed. The initial deposition following powder delivery was significantly larger in the ciliated mucosa of the upper and posterior nasal regions, whereas less was deposited in the lower regions. Overall nasal clearance of powder was slower initially, but due to retention in anterior nonciliated regions the overall nasal clearance after spray was slower.

Ceramic oxide powders and the formation thereof

DOEpatents

Katz, Joseph L.; Hung, Cheng-Hung

1993-01-01

Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

21 CFR 169.179 - Vanilla powder.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Vanilla powder. 169.179 Section 169.179 Food and... § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or vanilla oleoresin...) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the...

21 CFR 169.179 - Vanilla powder.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Vanilla powder. 169.179 Section 169.179 Food and... § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or vanilla oleoresin...) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the...

21 CFR 169.179 - Vanilla powder.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Vanilla powder. 169.179 Section 169.179 Food and... § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or vanilla oleoresin...) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the...

21 CFR 169.179 - Vanilla powder.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Vanilla powder. 169.179 Section 169.179 Food and... § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or vanilla oleoresin...) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the...

21 CFR 169.179 - Vanilla powder.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Vanilla powder. 169.179 Section 169.179 Food and... § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or vanilla oleoresin...) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the...

New technology for separating resin powder and fiberglass powder from fiberglass-resin powder of waste printed circuit boards.

PubMed

Li, Jia; Gao, Bei; Xu, Zhenming

2014-05-06

New recycling technologies have been developed lately to enhance the value of the fiberglass powder-resin powder fraction (FRP) from waste printed circuit boards. The definite aim of the present paper is to present some novel methods that use the image forces for the separation of the resin powder and fiberglass powder generated from FRP during the corona electrostatic separating process. The particle shape charactization and particle trajectory simulation were performed on samples of mixed non-metallic particles. The simulation results pointed out that particles of resin powder and particles of fiberglass powder had different detach trajectories at the conditions of the same size and certain device parameters. An experiment carried out using a corona electrostatic separator validated the possibility of sorting these particles based on the differences in their shape characteristics. The differences in the physical properties of the different types of particles provided the technical basis for the development of electrostatic separation technologies for the recycling industry.

Cheese powder as an ingredient in emulsion sausages: Effect on sensory properties and volatile compounds.

PubMed

Xiang, Chen; Ruiz-Carrascal, Jorge; Petersen, Mikael A; Karlsson, Anders H

2017-08-01

Different types of cheese powder were added to meat emulsion sausages in order to address its influence on chemical composition, volatile compounds profile and sensory properties, and its potential to reduce salt content through boosting saltiness. Addition of cheese powder to emulsion sausages modified their profile of volatile compounds. Blue cheese increased some ketones, alcohols, and esters, while brown cheese brought typical Maillard reaction compounds. Overall, addition of cheese powders to sausages enhanced the intensity of flavour traits. A mixture of hard and blue cheese powder showed the highest effect on boosting saltiness, while brown cheese powder showed the strongest umami and meat flavour boosting effect, and sausages with added blue cheese powder showed a more intense aftertaste. Hardness significantly increased due to the addition of blue cheese powder. Addition of cheese powder to emulsion sausages might be an interesting tool to boost flavour and reduce salt content in cooked sausages with no negative effect on saltiness or overall flavour. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sequential changes of main components in different kinds of milk powders using two-dimensional infrared correlation analysis

NASA Astrophysics Data System (ADS)

Zhou, Qun; Sun, Su-Qin; Yu, Lu; Xu, Chang-Hua; Noda, Isao; Zhang, Xin-Rong

2006-11-01

Infrared (IR) spectroscopy and two-dimensional (2D) correlation IR spectroscopy are shown to offer some information about stability and shelf life of milk powders without separation and extraction of individual components in this paper. Temperature has been chosen as the perturbation to monitor the infrared behavior of various milk powders, namely, whole milk powder (WMP), sweet whole milk powder (Sweet WMP), low-fat milk powder (LFMP), and skim milk powder (SMP). The sequential order of changes in protein, fat and carbohydrates (mainly lactose) in milk powders is studied for the first time. The protein changes before the sucrose in WMP, whereas the sucrose changes before the protein in Sweet WMP under temperature perturbation. It is also found that in SMP, carbohydrate changes prior to protein whereas in LFMP and WMP protein changes first as the temperature is increased. The conclusion can provide some useful reference to understand the thermal stability of milk powders.

Relationship of Powder Feedstock Variability to Microstructure and Defects in Selective Laser Melted Alloy 718

NASA Technical Reports Server (NTRS)

Smith, T. M.; Kloesel, M. F.; Sudbrack, C. K.

2017-01-01

Powder-bed additive manufacturing processes use fine powders to build parts layer by layer. For selective laser melted (SLM) Alloy 718, the powders that are available off-the-shelf are in the 10-45 or 15-45 micron size range. A comprehensive investigation of sixteen powders from these typical ranges and two off-nominal-sized powders is underway to gain insight into the impact of feedstock on processing, durability and performance of 718 SLM space-flight hardware. This talk emphasizes an aspect of this work: the impact of powder variability on the microstructure and defects observed in the as-fabricated and full heated material, where lab-scale components were built using vendor recommended parameters. These typical powders exhibit variation in composition, percentage of fines, roughness, morphology and particle size distribution. How these differences relate to the melt-pool size, porosity, grain structure, precipitate distributions, and inclusion content will be presented and discussed in context of build quality and powder acceptance.

Preparation, chemical composition and storage studies of quamachil (Pithecellobium dulce L.) aril powder.

PubMed

Rao, Galla Narsing; Nagender, Allani; Satyanarayana, Akula; Rao, Dubasi Govardhana

2011-02-01

Quamachil aril powder samples were prepared and evaluated for chemical composition and sensory quality by packing in two packaging systems during storage for six months. The protein contents were 12.4 and 15.0% in white and pink aril powders respectively. The titrable acidity of white and pink aril powders were 2.4 and 4.8% respectively. Ca and Fe contents in white aril powder samples were 60 and 12 mg/100 g where as in pink aril powder 62 and 16 mg/100 g, respectively. The anthocyanin content in pink powder decreased from 50.5 to 11.2 and 14.1 mg/100 g in samples packed in polyethylene (PE) and metalised polyester polyethylene laminated pouches respectively. Total polyphenol amount increased in both the powders irrespective of packaging material. Sorption isotherms indicated that both white and pink aril powders were hygroscopic and equilibrated at low relative humidity of 28 and 32%, respectively.

Fabrication of Spherical AlSi10Mg Powders by Radio Frequency Plasma Spheroidization

NASA Astrophysics Data System (ADS)

Wang, Linzhi; Liu, Ying; Chang, Sen

2016-05-01

Spherical AlSi10Mg powders were prepared by radio frequency plasma spheroidization from commercial AlSi10Mg powders. The fabrication process parameters and powder characteristics were investigated. Field emission scanning electron microscope, X-ray diffraction, laser particle size analyzer, powder rheometer, and UV/visible/infrared spectrophotometer were used for analyses and measurements of micrographs, phases, granulometric parameters, flowability, and laser absorption properties of the powders, respectively. The results show that the obtained spherical powders exhibit good sphericity, smooth surfaces, favorable dispersity, and excellent fluidity under appropriate feeding rate and flow rate of carrier gas. Further, acicular microstructures of the spherical AlSi10Mg powders are composed of α-Al, Si, and a small amount of Mg2Si phase. In addition, laser absorption values of the spherical AlSi10Mg powders increase obviously compared with raw material, and different spectra have obvious absorption peaks at a wavelength of about 826 nm.

Sol-gel synthesis and densification of aluminoborosilicate powders. Part 1: Synthesis

NASA Technical Reports Server (NTRS)

Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

1992-01-01

Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowing air, the powders were amorphous with the metal oxides comprising 87 percent of the weight and uncombusted organics the remainder. DTA of dried powders revealed a T(sub g) at approximately 835 C and an exotherm near 900 C due to crystallization. Powders derived from aluminum secbutoxide consisted of particles with a mean diameter 5 microns less than those from aluminum isopropoxide. Powders synthesized with aluminum isopropoxide produced agglomerates comprised of rod shaped particulates while powders made with the secbutoxide precursor produced irregular glassy shards. Compacts formed from these powders required different loadings for equivalent densities according to the method of synthesis.

The mechanical and thermal characteristics of phenolic foam reinforced with kaolin powder and glass fiber fabric

NASA Astrophysics Data System (ADS)

Xiao, Wenya; Huang, Zhixiong; Ding, Jie

2017-12-01

In this work, kaolin powder and glass fiber fabric were added to PF in order to improve its thermal stability and mechanical property. Micro-structures of carbonized PF with kaolin powder were inspected by scanning electron microscopy (SEM) to demonstrate the filler’s pinning effect. SEM results illustrated modified PF had well morphology after high-temperature heat treatment. The Fourier transform infrared spectrometer (FTIR) test was carried out and found that kaolin powder only physically dispersed in PF. The compression test and thermal weight loss test were done on two groups of modified PF (Group A: add powder and fabric; Group B: add powder only). Results showed that all modified PF were better than pure PF, while foams with powder and fabric showed better mechanical characteristic and thermal stability compared with foams with powder only.

Computer Vision and Machine Learning for Autonomous Characterization of AM Powder Feedstocks

NASA Astrophysics Data System (ADS)

DeCost, Brian L.; Jain, Harshvardhan; Rollett, Anthony D.; Holm, Elizabeth A.

2017-03-01

By applying computer vision and machine learning methods, we develop a system to characterize powder feedstock materials for metal additive manufacturing (AM). Feature detection and description algorithms are applied to create a microstructural scale image representation that can be used to cluster, compare, and analyze powder micrographs. When applied to eight commercial feedstock powders, the system classifies powder images into the correct material systems with greater than 95% accuracy. The system also identifies both representative and atypical powder images. These results suggest the possibility of measuring variations in powders as a function of processing history, relating microstructural features of powders to properties relevant to their performance in AM processes, and defining objective material standards based on visual images. A significant advantage of the computer vision approach is that it is autonomous, objective, and repeatable.

Production of fine calcium powders by centrifugal atomization with rotating quench bath

DOE PAGES

Tian, Liang; Ames Lab. and Iowa State Univ., Ames, IA; Anderson, Iver; ...

2016-02-08

Recently, a novel Al/Ca composite was produced by severe plastic deformation of Al powders and Ca granules for possible use as a high-voltage power transmission conductor. Since the strength of such composites is inversely proportional to the Ca filament size, fine Ca powders (less than ~250 μm) are needed to achieve the desired high strength for the powder metallurgy production of an Al-matrix composite reinforced by nano-scale Ca filaments. However, fine Ca powders are not commercially available. Therefore, we have developed a method to produce fine Ca powders via centrifugal atomization to supply Ca powder for prototype development of Al/Camore » composite conductor. A secondary goal of the project was to demonstrate that Ca powder can be safely prepared, stored, and handled and could potentially be scaled for commercial production. Our results showed that centrifugal atomization can yield as much as 83 vol. % Ca powder particles smaller than 250 μm. The mean particle size sometimes matches, sometimes deviates substantially from the predictions of the Champagne & Anger equation likely due to unexpected secondary atomization. The particle size distribution is typical for a ligament-disintegration atomization mode. Scanning electron micrographs showed that the morphology of these Ca powders varied with powder size. Spark testing and auto-ignition tests indicated that the atomized powders were difficult to ignite, providing confidence that this material can be handled safely in air.« less

[A technological study on the extraction of ultra-fine powder of Panax notoginsen].

PubMed

Huang, Yaohai; Huang, Mingqing; Zeng, Huifang; Guo, Wei; Xi, Ping

2005-12-01

To investigate the extraction of ultra-fine powder Panax notoginsen. The extraction rate of ginseng saponin Rg1, Re, Rb1, notoginseng saponin R1 and filtrated time were determined by alcoholic and aqueous extraction of Panax notoginsen in tablet, coarse powder, ultra-fine powder and recostitution granules of ultra-fine powder. The filtered time of ultra-fine powder of Panax notoginsen extraction and that of the tablet of Panax notoginsen extraction were similar, while the extraction rates of various saponins of it were high. The method of aqueous extrction in ltra-fine powder of Panax notoginsen is easy in filtrationer, higher in extraction rate of Panax notoginsen and lower in production cost.

Pyrophoric behaviour of uranium hydride and uranium powders

NASA Astrophysics Data System (ADS)

Le Guyadec, F.; Génin, X.; Bayle, J. P.; Dugne, O.; Duhart-Barone, A.; Ablitzer, C.

2010-01-01

Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (<0.5 wt.%) was obtained by heat treatment at low temperature in flowing Ar/5%H2. Pure uranium powder was obtained by dehydration in flowing pure argon. Those fine powders showed spontaneous ignition at room temperature in air. An in situ CCD-camera displayed ignition associated with powder temperature measurement. Characterization of powders before and after ignition was performed by XRD measurements and SEM observations. Oxidation mechanisms are proposed.

Container Prevents Oxidation Of Metal Powder

NASA Technical Reports Server (NTRS)

Woodford, William H.; Power, Christopher A.; Mckechnie, Timothy N.; Burns, David H.

1992-01-01

Sealed high-vacuum container holds metal powder required free of contamination by oxygen from point of manufacture to point of use at vacuum-plasma-spraying machine. Container protects powder from air during filling, storage, and loading of spraying machine. Eliminates unnecessary handling and transfer of powder from one container to another. Stainless-steel container sits on powder feeder of vacuum-plasma-spraying machine.

Ceramic oxide powders and the formation thereof

DOEpatents

Katz, J.L.; Chenghung Hung.

1993-12-07

Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

Micro-feeding and dosing of powders via a small-scale powder pump.

PubMed

Besenhard, M O; Fathollahi, S; Siegmann, E; Slama, E; Faulhammer, E; Khinast, J G

2017-03-15

Robust and accurate powder micro-feeding (<100mg/s) and micro-dosing (<5 mg) are major challenges, especially with regard to regulatory limitations applicable to pharmaceutical development and production. Since known micro-feeders that yield feed rates below 5mg/s use gravimetric feeding principles, feed rates depend primarily on powder properties. In contrast, volumetric powder feeders do not require regular calibration because their feed rates are primarily determined by the feeder's characteristic volume replacement. In this paper, we present a volumetric micro-feeder based on a cylinder piston system (i.e., a powder pump), which allows accurate micro-feeding and feed rates of a few grams per hours even for very fine powders. Our experimental studies addressed the influence of cylinder geometries, the initial conditions of bulk powder, and the piston speeds. Additional computational studies via Discrete Element Method simulations offered a better understanding of the feeding process, its possible limitations and ways to overcome them. The powder pump is a simple yet valuable tool for accurate powder feeding at feed rates of several orders of magnitude. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of surface energy on powder compactibility.

PubMed

Fichtner, Frauke; Mahlin, Denny; Welch, Ken; Gaisford, Simon; Alderborn, Göran

2008-12-01

The influence of surface energy on the compactibility of lactose particles has been investigated. Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The surface energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. All powders were amorphous and similar in particle size, shape, and surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive surface energy was dependent of the composition of the powders. The decrease in tablet strength correlated to the decrease in powder surface energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by surface energy which, in turn, can be altered by the presence of surfactants.

Defect Control of the WC Hardmetal by Mixing Recycled WC Nano Powder and Tungsten Powder

NASA Astrophysics Data System (ADS)

Hur, Man Gyu; Shin, Mi Kyung; Kim, Deug Joong; Yoon, Dae Ho

2018-03-01

Tungsten metal powder was added to recycled WC nano powder to control the macro and micro defects of WC hardmetal. The macro and micro defects caused by the excess carbon in the recycled WC powder were markedly removed after the addition of tungsten metal powder ranging from 2 to 6 wt%. The density and hardness of the WC hardmetals also increased due to the removal of defects after adding the tungsten metal powder. The density and hardness of WC hardmetals with the addition of W metal powder ranged from 8 to 12 wt% increased linearly as the W metal powder content increased due to the formation of a new (Co- and W-rich WC) composition. The surface morphology of the WC hardmetals was observed via field emission scanning electron microscopy, and a quantitative elemental analysis was conducted via X-ray fluorescence spectrometry and energy dispersive X-ray analysis. The density and hardness of the WC hardmetals were respectively measured using an analytical balance and a Vikers hardness tester. The effect on the defects in the recycled WC hardmetals through the addition of the tungsten metal powder was discussed in detail.

Effect of Particle Morphology on Cold Spray Deposition of Chromium Carbide-Nickel Chromium Cermet Powders

NASA Astrophysics Data System (ADS)

Fernandez, Ruben; Jodoin, Bertrand

2017-08-01

Nickel chromium-chromium carbide coatings provide good corrosion and wear resistance at high temperatures, making them ideal for applications where a harsh environment and high temperatures are expected. Thermal spray processes are preferred as deposition technique of cermets, but the high process temperatures can lead to decarburization and reduction of the coatings properties. Cold spray uses lower temperatures preventing decarburization. Since the metallic phase remains solid, the feedstock powder morphology becomes crucial on the deposition behavior. Six commercially available powders were studied, varying in morphology and metal/ceramic ratios. The powders were categorized into 4 groups depending on their morphology. Spherical powders lead to substrate erosion due to their limited overall ductility. Porous agglomerated and sintered powders lead to severely cracked coatings. For dense agglomerated and sintered powders, the outcome depended on the initial metal/ceramic ratio: powders with 25 wt.% NiCr led to substrate erosion while 35 wt.% NiCr powders led to dense coatings. Finally, blended ceramic-metal mixtures also lead to dense coatings. All coatings obtained had lower ceramic content than the initial feedstock powders. Interrupted spray tests, combined with FEA, helped drawing conclusions on the deposition behavior to explain the obtained results.

Time resolved fluorescence of cow and goat milk powder

NASA Astrophysics Data System (ADS)

Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

2017-01-01

Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

Physical characterization of whole and skim dried milk powders.

PubMed

Pugliese, Alessandro; Cabassi, Giovanni; Chiavaro, Emma; Paciulli, Maria; Carini, Eleonora; Mucchetti, Germano

2017-10-01

The lack of updated knowledge about the physical properties of milk powders aimed us to evaluate selected physical properties (water activity, particle size, density, flowability, solubility and colour) of eleven skim and whole milk powders produced in Europe. These physical properties are crucial both for the management of milk powder during the final steps of the drying process, and for their use as food ingredients. In general, except for the values of water activity, the physical properties of skim and whole milk powders are very different. Particle sizes of the spray-dried skim milk powders, measured as volume and surface mean diameter were significantly lower than that of the whole milk powders, while the roller dried sample showed the largest particle size. For all the samples the size distribution was quite narrow, with a span value less than 2. The loose density of skim milk powders was significantly higher than whole milk powders (541.36 vs 449.75 kg/m 3 ). Flowability, measured by Hausner ratio and Carr's index indicators, ranged from passable to poor when evaluated according to pharmaceutical criteria. The insolubility index of the spray-dried skim and whole milk powders, measured as weight of the sediment (from 0.5 to 34.8 mg), allowed a good discrimination of the samples. Colour analysis underlined the relevant contribution of fat content and particle size, resulted in higher lightness ( L *) for skim milk powder than whole milk powder, which, on the other hand, showed higher yellowness ( b *) and lower greenness (- a *). In conclusion a detailed knowledge of functional properties of milk powders may allow the dairy to tailor the products to the user and help the food processor to perform a targeted choice according to the intended use.

Nifedipine capsules may provide a viable alternative to oral powders for paediatric patients.

PubMed

Helin-Tanninen, M; Naaranlahti, T; Kontra, K; Savolainen, K

2007-02-01

To compare content uniformities between different sizes of extemporaneously compounded nifedipine oral powders and capsules, in order to find out if capsules could be used instead of oral powders as paediatric medications. Actual content and content uniformity of extemporaneously compounded 1-mg nifedipine oral powders and capsules were evaluated by a high performance liquid chromatographic assay. Capsules and powders were prepared by triturating 10-mg nifedipine tablets with different amounts of lactose or microcrystalline cellulose with a mortar and pestle using a standard geometric dilution technique. Oral powders were weighed individually and capsules were filled by a hand-operated capsule-filling machine. Four different sizes of powders (500, 300, 100 and 50 mg) and three different sizes of capsules (numbers 1, 3 and 4) were prepared. Ten oral powders and 10 capsules from each batch were randomly selected and individually assayed for nifedipine amount. The extemporaneously prepared nifedipine oral powders and capsules were within acceptable limits for content uniformity, as defined by the European Pharmacopoeia, but the results indicate that the loss of nifedipine during the preparation process may be considerable for both preparations. The concentration on nifedipine decreased while the total mass of the oral powder decreased. These results demonstrate that nifedipine oral powders can be replaced by capsules, whose contents are emptied for use, in paediatric medications. Compounding small capsules, such as size number 3 or 4, is acceptable when considering the average drug content. The total weight of the oral powder should be at least 300 mg. The preparation of nifedipine in all studied capsule sizes was safe with either lactose monohydrate or microcrystalline cellulose as excipients. Thus, emptied capsules seem to be a good choice for delivering a paediatric medication. The loss of nifedipine was considerable in oral powders with low total weight.

Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

NASA Technical Reports Server (NTRS)

Whitman, Pamela K.; Feke, Donald L.

1986-01-01

The effects of various powder treatment strategies on the colloid chemistry of aqueous dispersions of silicon carbide and silicon nitride are examined using a surface titration methodology. Pretreatments are used to differentiate between the true surface chemistry of the powders and artifacts resulting from exposure history. Silicon nitride powders require more extensive pretreatment to reveal consistent surface chemistry than do silicon carbide powders. As measured by titration, the degree of proton adsorption from the suspending fluid by pretreated silicon nitride and silicon carbide powders can both be made similar to that of silica.

Counterflow diffusion flame synthesis of ceramic oxide powders

DOEpatents

Katz, J.L.; Miquel, P.F.

1997-07-22

Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity. 24 figs.

Counterflow diffusion flame synthesis of ceramic oxide powders

DOEpatents

Katz, Joseph L.; Miquel, Philippe F.

1997-01-01

Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity.

Explosion risk evaluation during production of coating powder.

PubMed

Li, Gang; Yuan, Chunmiao; Chen, Baozhi

2007-10-22

Powder coating is widely used in industry to prevent equipment corrosion. More than 600 companies produce coating powder in China, but most do not understand the explosion hazard of such products. In the present investigation the explosibility parameters of a coating powder were determined. Results showed that the coating powder is explosible, though the ignition energy is higher than those of normal dusts such as coal powder and corn starch. Based on these experimental findings, a systematic explosion protection method is proposed, with explosion isolation and explosion venting being adopted as the main protective methods.

Functionally Graded Materials by Laser Metal Deposition (PREPRINT)

DTIC Science & Technology

2010-03-01

composition of Fe-82 wt% V (powder-1) and Inconel - 625 (powder-2) powders are listed in Table 1. The substrate materials used for the experiment were cold...like laser power, travel speed and powder feed rate is yet to be determined to obtain a successful FGM. Inconel - 625 deposits showed macro-cracks...Composition (wt%) Powder-1: Fe-82 wt% V V (82), Al (0.68), Si (0.9), C (0.07), S (0.01), P (0.02), Fe (18) Powder-2: Inconel - 625 Ni (58), Cr (20-23

Fabrication of spherical high-nitrogen stainless steel powder alloys by mechanical alloying and thermal plasma spheroidization

NASA Astrophysics Data System (ADS)

Razumov, Nikolay G.; Wang, Qing Sheng; Popovich, Anatoly A.; Shamshurin, Aleksey I.

2018-04-01

This paper describes the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a radio frequency thermal plasma. The as-milled powder with irregular particles were successfully converted into spherical high-nitrogen stainless steel powder alloy. Measurement of the residual nitrogen content in the obtained powder, shown that during the plasma spheroidization process, part of the nitrogen escapes from the alloy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Liang; Ames Lab. and Iowa State Univ., Ames, IA; Anderson, Iver

Recently, a novel Al/Ca composite was produced by severe plastic deformation of Al powders and Ca granules for possible use as a high-voltage power transmission conductor. Since the strength of such composites is inversely proportional to the Ca filament size, fine Ca powders (less than ~250 μm) are needed to achieve the desired high strength for the powder metallurgy production of an Al-matrix composite reinforced by nano-scale Ca filaments. However, fine Ca powders are not commercially available. Therefore, we have developed a method to produce fine Ca powders via centrifugal atomization to supply Ca powder for prototype development of Al/Camore » composite conductor. A secondary goal of the project was to demonstrate that Ca powder can be safely prepared, stored, and handled and could potentially be scaled for commercial production. Our results showed that centrifugal atomization can yield as much as 83 vol. % Ca powder particles smaller than 250 μm. The mean particle size sometimes matches, sometimes deviates substantially from the predictions of the Champagne & Anger equation likely due to unexpected secondary atomization. The particle size distribution is typical for a ligament-disintegration atomization mode. Scanning electron micrographs showed that the morphology of these Ca powders varied with powder size. Spark testing and auto-ignition tests indicated that the atomized powders were difficult to ignite, providing confidence that this material can be handled safely in air.« less

Influence of Powder Morphology and Microstructure on the Cold Spray and Mechanical Properties of Ti6Al4V Coatings

NASA Astrophysics Data System (ADS)

Munagala, Venkata Naga Vamsi; Akinyi, Valary; Vo, Phuong; Chromik, Richard R.

2018-06-01

The powder microstructure and morphology has significant influence on the cold sprayability of Ti6Al4V coatings. Here, we compare the cold sprayability and properties of coatings obtained from Ti6Al4V powders of spherical morphology (SM) manufactured using plasma gas atomization and irregular morphology (IM) manufactured using the Armstrong process. Coatings deposited using IM powders had negligible porosity and better properties compared to coatings deposited using SM powders due to higher particle impact velocities, porous surface morphology and more deformable microstructure. To evaluate the cohesive strength, multi-scale indentation was performed and hardness loss parameter was calculated. Coatings deposited using SM powders exhibited poor cohesive strength compared to coatings deposited using IM powders. Images of the residual indents showed de-bonding and sliding of adjacent splats in the coatings deposited using SM powders irrespective of the load. Coatings deposited using IM powders showed no evidence of de-bonding at low loads. At high loads, splat de-bonding was observed resulting in hardness loss despite negligible porosity. Thus, while the powders from Armstrong process lead to a significant improvement in sprayability and coating properties, further optimization of powder and cold spray process will be required as well as consideration of post-annealing treatments to obtain acceptable cohesive strength.

Physical and Sensory Properties of Ice Cream Containing Fermented Pepper Powder.

PubMed

Yeon, Su-Jung; Kim, Ji-Han; Hong, Go-Eun; Park, Woojoon; Kim, Soo-Ki; Seo, Han-Geuk; Lee, Chi-Ho

2017-01-01

This study was conducted to investigate the physical and sensory properties of ice cream containing fermented pepper powder. Three ice cream formulas were manufactured: 1, control; 2, supplemented with 0.1% fermented pepper powder; and 3, supplemented with 0.2% fermented pepper powder. Formulas 2 and 3 had significantly higher viscosity and lower overrun than formula 1 ( p <0.05). Additionally, ice creams supplemented with fermented pepper powder were harder and maintained their forms longer than the controls. 0.2% fermented pepper powder added ice cream had no pungency as much as that of control and overall sensory attribute was not significantly different from control. Therefore, ice cream containing fermented pepper powder maintained physical and sensory properties similar to the controls, and maintenance was better. It means fermented pepper powder ice cream can be utilized as the material of functional food (dessert).

Physical and Sensory Properties of Ice Cream Containing Fermented Pepper Powder

PubMed Central

Kim, Soo-Ki; Seo, Han-Geuk

2017-01-01

This study was conducted to investigate the physical and sensory properties of ice cream containing fermented pepper powder. Three ice cream formulas were manufactured: 1, control; 2, supplemented with 0.1% fermented pepper powder; and 3, supplemented with 0.2% fermented pepper powder. Formulas 2 and 3 had significantly higher viscosity and lower overrun than formula 1 (p<0.05). Additionally, ice creams supplemented with fermented pepper powder were harder and maintained their forms longer than the controls. 0.2% fermented pepper powder added ice cream had no pungency as much as that of control and overall sensory attribute was not significantly different from control. Therefore, ice cream containing fermented pepper powder maintained physical and sensory properties similar to the controls, and maintenance was better. It means fermented pepper powder ice cream can be utilized as the material of functional food (dessert). PMID:28316469

Characteristics of Fe powders prepared by spray pyrolysis from a spray solution with ethylene glycol as the source material of heat pellet

NASA Astrophysics Data System (ADS)

Koo, H. Y.; Kim, J. H.; Hong, S. K.; Ko, Y. N.; Jang, H. C.; Jung, D. S.; Han, J. M.; Hong, Y. J.; Kang, Y. C.; Kang, S. H.; Cho, S. B.

2012-06-01

Fe powders as the heat pellet material for thermal batteries are prepared from iron oxide powders obtained by spray pyrolysis from a spray solution of iron nitrate with ethylene glycol. The iron oxide powders with hollow and thin wall structure produce Fe powders with elongated structure and fine primary particle size at a low reducing temperature of 615 °C. The mean size of the primary Fe powders with elongated structure decreases with increasing concentration of ethylene glycol dissolved into the spray solution. The heat pellets prepared from the fine-size Fe powders with elongated structure have good ignition sensitivities below 1 watt. The heat pellets formed from the Fe powders obtained from the spray solution with 0.5 M EG have an extremely high burn rate of 26 cms-1.

Influence of small particles inclusion on selective laser melting of Ti-6Al-4V powder

NASA Astrophysics Data System (ADS)

Gong, Haijun; Dilip, J. J. S.; Yang, Li; Teng, Chong; Stucker, Brent

2017-12-01

The particle size distribution and powder morphology of metallic powders have an important effect on powder bed fusion based additive manufacturing processes, such as selective laser melting (SLM). The process development and parameter optimization require a fundamental understanding of the influence of powder on SLM. This study introduces a pre-alloyed titanium alloy Ti-6Al-4V powder, which has a certain amount of small particles, for SLM. The influence of small particle inclusion is investigated through microscopy of surface topography, elemental and microstructural analysis, and mechanical testing, compared to the Ti-6Al-4V powder provided by SLM machine vendor. It is found that the small particles inclusion in Ti-6Al-4V powder has a noticeable effect on extra laser energy absorption, which may develop imperfections and deteriorate the SLM fatigue performance.

Influence of grinding on service properties of VT-22 powder applied in additive technologies

NASA Astrophysics Data System (ADS)

Zakharov, M. N.; Rybalko, O. F.; Romanova, O. V.; Gelchinskiy, B. R.; Il'inykh, S. A.; Krashaninin, V. A.

2017-01-01

Powder of titanium alloy (VT-22) produced by plasma-spraying was subjected to grinding to obtain powder with size less 100 microns. These powders were sprayed by plasma unit using two types of gases, namely, air and air with methane (spraying in water and sputtering of coating on steel support). Influence of grinding time on yield of powder of required fraction was studied. Morphology and phase composition of the grinded powder and plasma sprayed one were under investigation. In the result of experiments, it appears that the grinding time genuinely influences the chemical and phase compositions, but there is no effect on physical-processing properties. For powders after plasma spraying some changes of non-metal elements content were detected by chemical analysis. Using gaseous mixture of air and methane in plasma spraying unit leads to formation of a new phase in the powder according X-ray diffraction data.

Bimodal metal micro-nanopowders for powder injection molding

NASA Astrophysics Data System (ADS)

Pervikov, Aleksandr; Rodkevich, Nikolay; Glazkova, Elena; Lerner, Marat

2017-12-01

The paper studies a bimodal metal powder composition designed to prepare feedstock for powder injection molding, as well as microstructure and porosity of sintered pats. Two kinds of metal powder compositions are used, in particular, a mixture of micro- and nanopowders and a bimodal powder prepared with dispersion of steel wire. The feedstock is prepared by mixing a bimodal metal powder composition with acetylacetone and paraffin wax. The microstructure of the debound parts is observed by scanning electron microscopy. The sintered parts are characterized by density measurements and metallographic analysis. The technique of the metal powder composition proves to affect the characteristics of sintered parts. Nanoparticles are shown in the interstitial spaces among the microparticles upon mixing micro- and nanopowders, but the regular distribution of nanoparticles on the surface of microparticles is observed in the bimodal powder providing the reduction of the porosity of sintered parts and increasing the density to the proper density of steel.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, R.

1998-08-04

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, Raghunath

1998-01-01

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

Effect of IN718 Recycled Powder Reuse on Properties of Parts Manufactured by Means of Selective Laser Melting

NASA Astrophysics Data System (ADS)

Ardila, L. C.; Garciandia, F.; González-Díaz, J. B.; Álvarez, P.; Echeverria, A.; Petite, M. M.; Deffley, R.; Ochoa, J.

Powder quality control is essential to obtain parts with suitable mechanical properties in Selective Laser Melting manufacturing technique. One of the most important advantages of suchtechnique is that it allows an efficient use of the material, due to the possibility to recycle and reuse un-melted powder. Nevertheless, powder material properties may change due to repeated recycling, affecting this way the mechanicalbehavior of parts. In this paper the effect of powder reuse on its quality and on the mechanical properties of the resulting melted parts is studied via self-developed recycling methodology. The material considered for investigation was IN718, a nickel superalloy widely used in industry. After recycling powder up to 14 times, no significant changes were observed in powder and test parts properties. The results obtained in this work will help to validate powder recycling methodology for its use in current industrial Selective Laser Melting manufacturing.

Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder.

PubMed

Li, Jiaxiang; Li, Yunping; Wang, Zhongchang; Bian, Huakang; Hou, Yuhang; Wang, Fenglin; Xu, Guofu; Liu, Bin; Liu, Yong

2016-12-22

The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service.

Synthesis and improved explosion behaviors of aluminum powders coated with nano-sized nickel film

NASA Astrophysics Data System (ADS)

Kim, Kyung Tae; Kim, Dong Won; Kim, Soo Hyung; Kim, Chang Kee; Choi, Yoon Jeong

2017-09-01

Nickel (Ni) materials with a thickness of a few hundred nm were homogeneously coated on the surfaces of aluminum (Al) powders by an electroless plating process. The Ni-coated Al powders show characteristic interfacial structures mixed of Ni, Al and O instead of densely packed Al oxide at the surface. The explosion test of the Ni-coated Al powders utilizing flame ignition showed that the powders had a 3.6 times enhanced pressurization rate of 405 kPa/ms compared to 111 kPa/ms of uncoated Al powders. It was found that this is due to a feasible diffusion of oxygen atoms into the Al powders through the thin and rough interfacial layers present at the Ni/Al interface. These results clearly indicate that nano-sized Ni film introduced instead of surface oxide acts as a very profitable layer to achieve efficient combustion behaviors by a rapid oxidation of Al powders.

Method to blend separator powders

DOEpatents

Guidotti, Ronald A.; Andazola, Arthur H.; Reinhardt, Frederick W.

2007-12-04

A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

Ballistic Characterization of the Scalability of Magnesium Alloy AMX602

DTIC Science & Technology

2015-07-01

Powder Metallurgy 4 5. Fabrication Procedure 4 6. Mechanical Property Analysis 5 7. Ballistic Experimental Procedures 6 8. Ballistic Experimental...compositions of noncombustive Mg alloy powders 4. Powder Metallurgy The powder was consolidated at room temperature using a 2,000-kN hydraulic press...evaluation of advanced powder metallurgy magnesium alloys for dynamic applications. Aberdeen Proving Ground (MD): Army Research Laboratory (US); 2009 May

Phase Stabilization of Zirconia.

DTIC Science & Technology

1997-01-30

preparing stabilized zirconia pursuant to this disclosure, an insoluble alumina powder is mixed with zirconia powder using a liquid dispersant, such...in a drying oven or a furnace. When mixing the alumina and zirconia powders , it is not necessary to have zirconia in any particular phase to achieve...phase stabilization, as disclosed herein. When mixed with alumina powder, zirconia powder can be in cubic, tetragonal or 20 monoclinic phases

Effect of the powder characteristics of Sisub3Nsub4 on the microstructure of sintered bodies

NASA Technical Reports Server (NTRS)

Woetting, G.; Hausner, H.

1981-01-01

Silicon nitride powders sintered with the addition of 2 wt% Mg0 to 95% theoretical density after attrition milling and subsequent purification were evaluated. Preparation of the powders is described. The powder characteristics (specific surfaces, iron concentration, and oxygen content), and density, weight loss, and phase state of the sinter bodies as a function of powder preparation are presented.

Low cost synthesis of TiO2-C nanocomposite powder for high efficiency visible light photocatalysis

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-04-01

Titanium dioxide-carbon nanocomposite powder was synthesized via a low cost chemical route using oleic acid and titanium tetra-isopropoxide. Since the carbon remained mainly on the surface of the TiO2 nanoparticles, the powder had black color. The composition of the powder was analyzed by X-ray photoelectron spectroscopy and the structure was studied with X-ray diffraction and transmission electron microscopy. The visible photocatalytic activity of the black TiO2 powder was investigated by studying the photo-bleaching of methylene blue under visible light. Our experimental observation showed that the black-TiO2 powder had a higher visible photocatalytic activity compared to the commercial TiO2 powder (P25 Degussa).

Granulation of fine powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ching-Fong

A mixture of fine powder including thorium oxide was converted to granulated powder by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated powder was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated powder relies on the thermal bonding to maintain its shape and structure. The granulated powder contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated powder was pressed and sintered to formmore » a dense compact with a higher density and more uniform pore size distribution.« less

Electrostatic powder coating: Principles and pharmaceutical applications.

PubMed

Prasad, Leena Kumari; McGinity, James W; Williams, Robert O

2016-05-30

A majority of pharmaceutical powders are insulating materials that have a tendency to accumulate charge. This phenomenon has contributed to safety hazards and issues during powder handling and processing. However, increased understanding of this occurrence has led to greater understanding and control of processing and product performance. More recently, the charging of pharmaceutical powders has been employed to adopt electrostatic powder coating as a pharmaceutical process. Electrostatic powder coating is a mature technology used in the finishing industry and much of that knowledge applies to its use in pharmaceutical applications. This review will serve to summarize the principles of electrostatic powder coating and highlight some of the research conducted on its use for the preparation of pharmaceutical dosage forms. Copyright © 2016 Elsevier B.V. All rights reserved.

Superconducting YBa2Cu3O7 Powder: Reduction of Carbon, Moisture, and Impurity Phase Concentrations in Commercial Powders and the Reactivity with Moisture and Carbon Dioxide

NASA Technical Reports Server (NTRS)

Stecura, Stephan

1994-01-01

The purpose of this study was to determine the experimental parameters under which commercially pure YBa2Cu3O7 (1237) powders would be converted into a single phase (1237) powder only. Carbon (present as carbonate) and impurity phase concentrations in the (1237) powder are very dependent upon the firing temperatures, heat-treating temperatures and times, and atmosphere, while the moisture concentration is not. YBa2Cu3O7 powder with about 0.03 wt/%, carbon, 0.03 wt% moisture, and low impurity phase concentrations was obtained. Moisture and carbon concentrations in heat-treated powders did not increase significantly after 48 and 72 h of exposure to air, respectively, and after 144 h of exposure they were less than 0.26 and 0.08 wt/%, respectively. The (1237) powder first reacts with moisture and then hydroxide reacts with CO2. Firing the as received powders in air led to the decomposition of the superconducting (1237) phase.

Thermal decomposition behavior of nano/micro bimodal feedstock with different solids loading

NASA Astrophysics Data System (ADS)

Oh, Joo Won; Lee, Won Sik; Park, Seong Jin

2018-01-01

Debinding is one of the most critical processes for powder injection molding. The parts in debinding process are vulnerable to defect formation, and long processing time of debinding decreases production rate of whole process. In order to determine the optimal condition for debinding process, decomposition behavior of feedstock should be understood. Since nano powder affects the decomposition behavior of feedstock, nano powder effect needs to be investigated for nano/micro bimodal feedstock. In this research, nano powder effect on decomposition behavior of nano/micro bimodal feedstock has been studied. Bimodal powders were fabricated with different ratios of nano powder, and the critical solids loading of each powder was measured by torque rheometer. Three different feedstocks were fabricated for each powder depending on solids loading condition. Thermogravimetric analysis (TGA) experiment was carried out to analyze the thermal decomposition behavior of the feedstocks, and decomposition activation energy was calculated. The result indicated nano powder showed limited effect on feedstocks in lower solids loading condition than optimal range. Whereas, it highly influenced the decomposition behavior in optimal solids loading condition by causing polymer chain scission with high viscosity.

Predictive Simulation of Process Windows for Powder Bed Fusion Additive Manufacturing: Influence of the Powder Bulk Density.

PubMed

Rausch, Alexander M; Küng, Vera E; Pobel, Christoph; Markl, Matthias; Körner, Carolin

2017-09-22

The resulting properties of parts fabricated by powder bed fusion additive manufacturing processes are determined by their porosity, local composition, and microstructure. The objective of this work is to examine the influence of the stochastic powder bed on the process window for dense parts by means of numerical simulation. The investigations demonstrate the unique capability of simulating macroscopic domains in the range of millimeters with a mesoscopic approach, which resolves the powder bed and the hydrodynamics of the melt pool. A simulated process window reveals the influence of the stochastic powder layer. The numerical results are verified with an experimental process window for selective electron beam-melted Ti-6Al-4V. Furthermore, the influence of the powder bulk density is investigated numerically. The simulations predict an increase in porosity and surface roughness for samples produced with lower powder bulk densities. Due to its higher probability for unfavorable powder arrangements, the process stability is also decreased. This shrinks the actual parameter range in a process window for producing dense parts.

Predictive Simulation of Process Windows for Powder Bed Fusion Additive Manufacturing: Influence of the Powder Bulk Density

PubMed Central

Rausch, Alexander M.; Küng, Vera E.; Pobel, Christoph; Körner, Carolin

2017-01-01

The resulting properties of parts fabricated by powder bed fusion additive manufacturing processes are determined by their porosity, local composition, and microstructure. The objective of this work is to examine the influence of the stochastic powder bed on the process window for dense parts by means of numerical simulation. The investigations demonstrate the unique capability of simulating macroscopic domains in the range of millimeters with a mesoscopic approach, which resolves the powder bed and the hydrodynamics of the melt pool. A simulated process window reveals the influence of the stochastic powder layer. The numerical results are verified with an experimental process window for selective electron beam-melted Ti-6Al-4V. Furthermore, the influence of the powder bulk density is investigated numerically. The simulations predict an increase in porosity and surface roughness for samples produced with lower powder bulk densities. Due to its higher probability for unfavorable powder arrangements, the process stability is also decreased. This shrinks the actual parameter range in a process window for producing dense parts. PMID:28937633

N-type nano-silicon powders with ultra-low electrical resistivity as anode materials in lithium ion batteries

NASA Astrophysics Data System (ADS)

Yue, Zhihao; Zhou, Lang; Jin, Chenxin; Xu, Guojun; Liu, Liekai; Tang, Hao; Li, Xiaomin; Sun, Fugen; Huang, Haibin; Yuan, Jiren

2017-06-01

N-type silicon wafers with electrical resistivity of 0.001 Ω cm were ball-milled to powders and part of them was further mechanically crushed by sand-milling to smaller particles of nano-size. Both the sand-milled and ball-milled silicon powders were, respectively, mixed with graphite powder (silicon:graphite = 5:95, weight ratio) as anode materials for lithium ion batteries. Electrochemical measurements, including cycle and rate tests, present that anode using sand-milled silicon powder performed much better. The first discharge capacity of sand-milled silicon anode is 549.7 mAh/g and it is still up to 420.4 mAh/g after 100 cycles. Besides, the D50 of sand-milled silicon powder shows ten times smaller in particle size than that of ball-milled silicon powder, and they are 276 nm and 2.6 μm, respectively. In addition, there exist some amorphous silicon components in the sand-milled silicon powder excepting the multi-crystalline silicon, which is very different from the ball-milled silicon powder made up of multi-crystalline silicon only.

Preparation of lead-zirconium-titanium film and powder by electrodeposition

DOEpatents

Bhattacharya, Raghu N.; Ginley, David S.

1995-01-01

A process for the preparation of lead-zirconium-titanium (PZT) film and powder compositions. The process comprises the steps of providing an electrodeposition bath, providing soluble salts of lead, zirconium and titanium metals to this bath, electrically energizing the bath to thereby direct ions of each respective metal to a substrate electrode and cause formation of metallic particles as a recoverable film of PZT powder on the electrode, and also recovering the resultant film as a powder. Recovery of the PZT powder can be accomplished by continually energizing the bath to thereby cause powder initially deposited on the substrate-electrode to drop therefrom into the bath from which it is subsequently removed. A second recovery alternative comprises energizing the bath for a period of time sufficient to cause PZT powder deposition on the substrate-electrode only, from which it is subsequently recovered. PZT film and powder so produced can be employed directly in electronic applications, or the film and powder can be subsequently oxidized as by an annealing process to thereby produce lead-zirconium-titanium oxide for use in electronic applications.

Preparation of lead-zirconium-titanium film and powder by electrodeposition

DOEpatents

Bhattacharya, R.N.; Ginley, D.S.

1995-10-31

A process is disclosed for the preparation of lead-zirconium-titanium (PZT) film and powder compositions. The process comprises the steps of providing an electrodeposition bath, providing soluble salts of lead, zirconium and titanium metals to this bath, electrically energizing the bath to thereby direct ions of each respective metal to a substrate electrode and cause formation of metallic particles as a recoverable film of PZT powder on the electrode, and also recovering the resultant film as a powder. Recovery of the PZT powder can be accomplished by continually energizing the bath to thereby cause powder initially deposited on the substrate-electrode to drop therefrom into the bath from which it is subsequently removed. A second recovery alternative comprises energizing the bath for a period of time sufficient to cause PZT powder deposition on the substrate-electrode only, from which it is subsequently recovered. PZT film and powder so produced can be employed directly in electronic applications, or the film and powder can be subsequently oxidized as by an annealing process to thereby produce lead-zirconium-titanium oxide for use in electronic applications. 4 figs.

Magnetic Properties of Amorphous Fe-Si-B Powder Cores Mixed with Pure Iron Powder

NASA Astrophysics Data System (ADS)

Kim, Hyeon-Jun; Nam, Seul Ki; Kim, Kyu-Sung; Yoon, Sung Chun; Sohn, Keun-Yong; Kim, Mi-Rae; Sul Song, Yong; Park, Won-Wook

2012-10-01

Amorphous Fe-Si-B alloy was prepared by melt-spinning, and then the ribbons were pulverized and ball-milled to make the amorphous powder of ˜25 µm in size. Subsequently those were mixed with pure iron powders with an average particle size of 3 µm, and 1.5 wt % water glass diluted by distilled water at the ratio of 1:2. The powder mixtures were cold compacted at 650 MPa in toroid die, and heat treated at 430-440 °C under a nitrogen atmosphere for 1 h and 30 min, respectively. The soft magnetic properties of powder core were investigated using a B-H analyzer and a flux meter at the frequency range of ˜100 kHz. The microstructure was observed using scanning electron microscope (SEM), and the density of the core was measured using the principle of Archimedes. Based on the experimental results, the amorphous powder mixed with pure iron powder showed the improved powder compactability, which resulted in the increased permeability and the reduced core loss.

The investigation of die-pressing and sintering behavior of ITP CP-Ti and Ti-6Al-4V powders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei; Yamamoto, Yukinori; Peter, William H

This paper investigated the die-pressing and sintering behavior of the low-cost CP-Ti and Ti-6Al- 4V powders made by the Armstrong Process . The Armstrong powders have an irregular coral like, dendritic morphology, with a dendrite size of approximately 2-5 m. As-received as well as milled powders were uniaxially pressed at designated pressures up to 690 MPa to form disk samples with different aspect ratios. In the studied pressure range, an empirical powder compaction equation was applied to linearize the green density pressure relationship, and powder compaction parameters were obtained. The Armstrong Ti-64 powder exhibited a significantly higher sinterability than themore » CP-Ti powder. This was explained to be due to the higher diffusivity of V at the sintering temperature. The Ti-64 samples with a green density of 71.0% increased to 99.6% after sintering at 1300oC for 1 hour. An ex-situ technique was used to track the powder morphology change before and after sintering.« less

Experimental Study of Structure/Behavior Relationship for a Metallized Explosive

NASA Astrophysics Data System (ADS)

Bukovsky, Eric; Reeves, Robert; Gash, Alexander; Glumac, Nick

2017-06-01

Metal powders are commonly added to explosive formulations to modify the blast behavior. Although detonation velocity is typically reduced compared to the neat explosive, the metal provides other benefits. Aluminum is a common additive to increase the overall energy output and high-density metals can be useful for enhancing momentum transfer to a target. Typically, metal powder is homogeneously distributed throughout the material; in this study, controlled distributions of metal powder in explosive formulations were investigated. The powder structures were printed using powder bed printing and the porous structures were filled with explosives to create bulk explosive composites. In all cases, the overall ratio between metal and explosive was maintained, but the powder distribution was varied. Samples utilizing uniform distributions to represent typical materials, discrete pockets of metal powder, and controlled, graded powder distributions were created. Detonation experiments were performed to evaluate the influence of metal powder design on the output pressure/time and the overall impulse. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Compact Process for the Preparation of Microfine Spherical High-Niobium-Containing TiAl Alloy Powders

NASA Astrophysics Data System (ADS)

Tong, J. B.; Lu, X.; Liu, C. C.; Wang, L. N.; Qu, X. H.

2015-03-01

High-Nb-containing TiAl alloys are a new generation of materials for high-temperature structural applications because of their superior high-temperature mechanical properties. The alloy powders can be widely used for additive manufacturing, thermal spraying, and powder metallurgy. Because of the difficulty of making microfine spherical alloy powders in quantity by conventional techniques, a compact method was proposed, which consisted of two-step ball milling of elemental powders and subsequent radio frequency (RF) argon plasma spheroidization. In comparison with conventional mechanical alloying techniques, the two-step milling process can be used to prepare alloy powders with uniform scale in a short milling time with no addition of process control agent. This makes the process effective and less contaminating. After RF argon plasma spheroidization, the powders produced exhibit good sphericity, and the number-average diameter is about 8.2 μm with a symmetric unimodal particle size distribution. The powders perform high composition homogeneity and contain predominately supersaturated α 2-Ti3Al phase. The oxygen and carbon contents of the spheroidized powder are 0.47% and 0.050%, respectively.

Method for synthesizing ultrafine powder materials

DOEpatents

Buss, Richard J.; Ho, Pauline

1988-01-01

A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

Improved Production Of Wrought Articles From Powders

NASA Technical Reports Server (NTRS)

Thomas, James R.; Singleton, Ogle R.

1994-01-01

Improved technique for consolidation of powders into dense articles developed. Peripheral bands used in consolidation, forging, and rolling operations. Facilitates consolidation of dispersion-hardened aluminous powders and composite mixtures for processing to such useful wrought articles as plates and sheets. Potential use in production of plates and sheets and perhaps other objects from "hard" powders, particularly from powders, objects made from which have propensity to crack when mechanically worked to other forms.

[Use of powder metallurgy for development of implants of Co-Cr-Mo alloy powder].

PubMed

Dabrowski, J R

2001-04-01

This paper discusses the application of powder metallurgy for the development of porous implantation materials. Powders obtained from Co-Cr-Mo alloy with different carbon content by water spraying and grinding, have been investigated. Cold pressing and rotary re-pressing methods were used for compressing the powder. It was found that the sintered materials obtained from water spraying have the most advantageous properties.

Experimental Equipment for Powder Processing

DTIC Science & Technology

2009-08-20

for a series of alumina and zirconia powder mixtures by TMDAR, CR-15 (alumina), as well as TZ3YS and CERAC-2003 (zirconia). The proportion of TMDAR...is known to cause abnormal grain growth. Fig.15 shows the seven representative curves obtained for our zirconia powder system. The 10% and 20...various zirconia powder mixtures. The maximum densification rate for each of our zirconia powder mixtures occurs within the relative density range of

Development of an Efficient Micro-Heat Exchanger: The Integration of Design Processing and Testing

DTIC Science & Technology

2005-11-01

together at high temperatures and cooled to room temperature. Additionally, alumina and zirconia powders have a major difference in densification...efficient heat exchanger. The main problem that needed to be resolved was the fact that the zirconia powders shrink much more than alumina powder...been measured. Our measurement in dimensions verifies that zirconia powders shrink substantially more than alumina powder except CR-15 after final

Polymer infiltration studies

NASA Technical Reports Server (NTRS)

Marchello, Joseph M.

1994-01-01

During the past three months, significant progress has been made on the preparation of carbon fiber composites using advanced polymer resins. The results are set forth in recent reports and publications, and will be presented at forthcoming national and international meetings. Current and ongoing research activities reported herein include: textile composites from powder-coated towpreg - role of surface coating in braiding; prepregger hot sled operation in making tape from powder coated tow; ribbonizing powder-impregnated towpreg; textile composites from powder-coated towpreg - role of bulk factor in consolidation; powder curtain prepreg process improvements in doctoring of powder; and hot/cold shoe for ATP open-section part warpage control.

Effect of the conditions of sintering of sodium-reduced tantalum powders on their characteristics

NASA Astrophysics Data System (ADS)

Prokhorova, T. Yu.; Orlov, V. M.; Miroshnichenko, M. N.; Kolosov, V. N.

2014-07-01

The effect of the granulation and heat treatment of sodium-reduced tantalum powders with a specific surface area of 2.5-3.6 m2/g on the bulk density, the powder flow time, and the specific surface area of the powders and the specific capacitance of the anodes made of them is studied. It is shown that heat treatment of a granulated powder in vacuum at 1100°C or in a mixture with magnesium at 800°C makes it possible to achieve the required powder flow time.

High Temperature Mechanical Behavior of Polycrystalline Alumina from Mixed Nanometer and Micrometer Powders

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2001-01-01

Sintered aluminum oxide materials were formed using commercial methods from mechanically mixed powders of nano-and micrometer alumina. The powders were consolidated at 1500 and 1600 C with 3.2 and 7.2 ksi applied stress in argon. The conventional micrometer sized powders failed to consolidate. While 100 percent nanometer-sized alumina and its mixture with the micrometer powders achieved less than 99 percent density. Preliminary high temperature creep behavior indicates no super-plastic strains. However high strains (less than 0.65 percent) were generated in the nanometer powder, due to cracks and linked voids initiated by cavitation.

Influence of Powder Characteristics on Processability of AlSi12 Alloy Fabricated by Selective Laser Melting

PubMed Central

Zherebtsov, Dmitry; Radionova, Ludmila

2018-01-01

Selective laser melting (SLM) is one of the additive manufacturing technologies that allows for the production of parts with complex shapes from either powder feedstock or from wires. Aluminum alloys have a great potential for use in SLM especially in automotive and aerospace fields. This paper studies the influence of starting powder characteristics on the processability of SLM fabricated AlSi12 alloy. Three different batches of gas atomized powders from different manufacturers were processed by SLM. The powders differ in particle size and its distribution, morphology and chemical composition. Cubic specimens (10 mm × 10 mm × 10 mm) were fabricated by SLM from the three different powder batches using optimized process parameters. The fabrication conditions were kept similar for the three powder batches. The influence of powder characteristics on porosity and microstructure of the obtained specimens were studied in detail. The SLM samples produced from the three different powder batches do not show any significant variations in their structural aspects. However, the microstructural aspects differ and the amount of porosity in these three specimens vary significantly. It shows that both the flowability of the powder and the apparent density have an influential role on the processability of AlSi12 SLM samples. PMID:29735932

Roller compaction of different pseudopolymorphic forms of theophylline: Effect on compressibility and tablet properties.

PubMed

Hadzović, Ervina; Betz, Gabriele; Hadzidedić, Seherzada; El-Arini, Silvia Kocova; Leuenberger, Hans

2010-08-30

The effect of roller compaction on disintegration time, dissolution rate and compressibility of tablets prepared from theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate was studied. In addition, the influence of adding microcrystalline cellulose, a commonly used excipient, in mixtures with these materials was investigated. Theophylline anhydrate powder was used as a model drug to investigate the influence of different compaction pressures on the tablet properties. Tablets with same porosity were prepared by direct compaction and by roller compaction/re-compaction. Compressibility was characterized by Heckel and modified Heckel equations. Due to the property of polymorphic materials to change their form during milling and compression, X-ray diffraction analysis of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate powders and granules was carried out. After roller compaction the disintegration time and the dissolution rate of the tablets were significantly improved. Compressibility of theophylline anhydrate powder and theophylline anhydrate fine powder was decreased, while theophylline monohydrate showed higher compressibility after roller compaction. Microcrystalline cellulose affected compressibility of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate whereby the binary mixtures showed higher compressibility than the individual materials. X-ray diffraction analyses confirmed that there were no polymorphic/pseudopolymorphic changes after roller compaction. Copyright 2010 Elsevier B.V. All rights reserved.

Influence of Powder Characteristics on Processability of AlSi12 Alloy Fabricated by Selective Laser Melting.

PubMed

Baitimerov, Rustam; Lykov, Pavel; Zherebtsov, Dmitry; Radionova, Ludmila; Shultc, Alexey; Prashanth, Konda Gokuldoss

2018-05-07

Selective laser melting (SLM) is one of the additive manufacturing technologies that allows for the production of parts with complex shapes from either powder feedstock or from wires. Aluminum alloys have a great potential for use in SLM especially in automotive and aerospace fields. This paper studies the influence of starting powder characteristics on the processability of SLM fabricated AlSi12 alloy. Three different batches of gas atomized powders from different manufacturers were processed by SLM. The powders differ in particle size and its distribution, morphology and chemical composition. Cubic specimens (10 mm × 10 mm × 10 mm) were fabricated by SLM from the three different powder batches using optimized process parameters. The fabrication conditions were kept similar for the three powder batches. The influence of powder characteristics on porosity and microstructure of the obtained specimens were studied in detail. The SLM samples produced from the three different powder batches do not show any significant variations in their structural aspects. However, the microstructural aspects differ and the amount of porosity in these three specimens vary significantly. It shows that both the flowability of the powder and the apparent density have an influential role on the processability of AlSi12 SLM samples.

Powder Bed Layer Characteristics: The Overseen First-Order Process Input

NASA Astrophysics Data System (ADS)

Mindt, H. W.; Megahed, M.; Lavery, N. P.; Holmes, M. A.; Brown, S. G. R.

2016-08-01

Powder Bed Additive Manufacturing offers unique advantages in terms of manufacturing cost, lot size, and product complexity compared to traditional processes such as casting, where a minimum lot size is mandatory to achieve economic competitiveness. Many studies—both experimental and numerical—are dedicated to the analysis of how process parameters such as heat source power, scan speed, and scan strategy affect the final material properties. Apart from the general urge to increase the build rate using thicker powder layers, the coating process and how the powder is distributed on the processing table has received very little attention to date. This paper focuses on the first step of every powder bed build process: Coating the process table. A numerical study is performed to investigate how powder is transferred from the source to the processing table. A solid coating blade is modeled to spread commercial Ti-6Al-4V powder. The resulting powder layer is analyzed statistically to determine the packing density and its variation across the processing table. The results are compared with literature reports using the so-called "rain" models. A parameter study is performed to identify the influence of process table displacement and wiper velocity on the powder distribution. The achieved packing density and how that affects subsequent heat source interaction with the powder bed is also investigated numerically.

Formulation and nutritional evaluation of a healthy vegetable soup powder supplemented with soy flour, mushroom, and moringa leaf.

PubMed

Farzana, Tasnim; Mohajan, Suman; Saha, Trissa; Hossain, Md Nur; Haque, Md Zahurul

2017-07-01

The research study was conducted to develop a healthy vegetables soup powder supplemented with soy flour, mushroom, moringa leaf and compare its nutritional facts with locally available soup powders. Proximate analysis and sensory evaluation were done by standard method. In this study, moisture, ash, protein, fat, fiber, carbohydrate, and energy content were ranged from 2.83% to 5.46%, 9.39% to 16.48%, 6.92% to 16.05%, 4.22% to 6.39%, 0.22% to 1.61%, 58.81% to 75.41%, and 337.42 to 386.72 kcal/100 g, respectively. Highest content of vitamin D, minerals, protein, and fiber and lowest content of moisture, fat, and carbohydrate were found in the presently developed soy-mushroom-moringa soup powder compare to locally available soup powders. Vitamin C was also found significantly higher than locally available soup powders S1, S2, and S3. Heavy metals were not found in any of the soup powders. On the sensory and microbiological point of view, the presently developed soup powder was found highly acceptable up to 6 months. So, the developed soy-mushroom-moringa soup powder is nutritionally superior to locally available soup powders and sufficient to meet day-to-day nutritional requirements as a supplement.

Effect of synthesis process on the microstructure and electrical conductivity of nickel/yttria-stabilized zirconia powders prepared by urea hydrolysis

NASA Astrophysics Data System (ADS)

Lin, Jyung-Dong; Wu, Zhao-Lun

In this study, NiO/YSZ composite powders were synthesized using hydrolysis on two solutions, one contains YSZ particles and Ni 2+ ion, and the other contains NiO particles, Zr 4+, and Y 3+ ions, with the aid of urea. The microstructure of the powders and sintered bulks was further characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicated that various synthesis processes yielded NiO/YSZ powders with different morphologies. The NiO precursors would deposit onto the surface of YSZ particles, and NiO-deposited YSZ composite powders were obtained. Alternatively, it was not observed that YSZ precursors deposited onto the surface of NiO particles, thus, a uniform powder mixture of fine NiO and fine YSZ particles was produced. After sintering and subsequent reduction, these powders would lead to the variations of Ni distribution in the YSZ matrix and conductivity of cermets. Owing to the core-shell structure of the powders and the higher size ratio of YSZ and NiO particles, the conductivity of cermet with NiO-deposited YSZ powders containing 23 wt% NiO is comparable to those with a NiO/YSZ powder mixture containing 50 wt% NiO.

Spheroidization by Plasma Processing and Characterization of Stainless Steel Powder for 3D Printing

NASA Astrophysics Data System (ADS)

Ji, Lina; Wang, Changzhen; Wu, Wenjie; Tan, Chao; Wang, Guoyu; Duan, Xuan-Ming

2017-10-01

Stainless steel 316L (SS 316L) powder was spheroidized by plasma processing to improve its suitability for powder 3D printing. The obtained spheroidized (sphero) powder was characterized in terms of its crystalline phases, elemental composition, morphology, particle size and distribution, light absorption, and flow properties. The elemental composition of the sphero powder met the Chinese standard for SS 316L except for its Si content. The volume fraction of ferrite increased after plasma processing. Furthermore, plasma processing was shown to not only reduce the mean size of the particles in the size range of 10 to 100 μm but also generate particles in the size range of 0.1 to 10 μm. The smaller particles filled the voids among larger particles, increasing the powder density. The light absorption was also increased owing to enhanced internal reflection. Although the basic flow energy decreased after plasma processing, the flow function (FF) value was smaller for the sphero powder, indicating a lower flowability of the sphero powder. However, the density of SS 316L pieces printed with commercial and sphero powders was 98.76 pct and 98.16 pct of the SS 316L bulk density, respectively, indicating the suitability of the sphero powder for 3D printing despite an FF below 10.

Rankine-Hugoniot relationships for molecular crystal explosives calculated using density functional theory based molecular dynamics

NASA Astrophysics Data System (ADS)

Mattsson, Ann E.; Wixom, Ryan R.; Mattsson, Thomas R.

2011-06-01

Density Functional Theory (DFT) has become a crucial tool for understanding the behavior of matter. The ability to perform high-fidelity calculations is most important for cases where experiments are impossible, dangerous, and/or prohibitively expensive to perform. For molecular crystals, successful use of DFT has been hampered by an inability to correctly describe the van der Waals' dominated equilibrium state. We have explored a way of bypassing this problem by using the Armiento-Mattsson 2005 (AM05) exchange-correlation functional. This functional is highly accurate for a wide range of solids, in particular in compression. Another advantage is that AM05 does not include any van der Waals' attraction. We will demonstrate the method on the PETN Hugoniot, and discuss our confidence in the results and ongoing research aimed at improvement. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Explosives detection and identification using surface plasmon-coupled emission

NASA Astrophysics Data System (ADS)

Ja, Shiou-Jyh

2012-06-01

To fight against the explosives-related threats in defense and homeland security applications, a smarter sensing device that not only detects but differentiates multiple true threats from false positives caused by environmental interferents is essential. A new optical detection system is proposed to address these issues by using the temporal and spectroscopic information generated by the surface plasmon coupling emission (SPCE) effect. Innovative SPCE optics have been designed using Zemax software to project the fluorescence signal into clear "rainbow rings" on a CCD with subnanometer wavelength resolution. The spectroscopic change of the fluorescence signal and the time history of such changes due to the presence of a certain explosive analyte are unique and can be used to identify explosives. Thanks to high optical efficiency, reporter depositions as small as 160-μm in diameter can generate a sufficient signal, allowing a dense array of different reporters to be interrogated with wavelength multiplexing and detect a wide range of explosives. We have demonstrated detection and classification of explosives, such as TNT, NT, NM, RDX, PETN, and AN, with two sensing materials in a prototype.

A deep towed explosive source for seismic experiments on the ocean floor

NASA Astrophysics Data System (ADS)

Koelsch, Donald E.; Witzell, Warren E.; Broda, James E.; Wooding, Frank B.; Purdy, G. M.

1986-12-01

A new seismic source for carrying out high resolution measurements of deep ocean crustal structure has been constructed and successfully used in a number of ocean bottom refraction experiments on the Mid Atlantic Ridge near 23° N. The source is towed within 100 m of the ocean floor on a conventional 0.68″ coaxial cable and is capable of firing, upon command from the research vessel, up to 48 individual 2.3 kg explosive charges. The explosive used was commercially available Penta-Erythritol-Tetra Nitrate (PETN) that was activated by 14.9 gm m-1 Primacord and DuPont E-97 electrical detonators. For safety reasons each detonator was fitted with a pressure switch that maintained a short until the source was at depth in excess of approximately 300 m. In addition, a mechanical protector isolated the detonator from the main charge and was only removed by the physical release of the explosive from the source package. These and other safety precautions resulted in several misfires but three experiments were successfully completed during the summer of 1985 at source depths of 3000 4000 m.

Explosive detection using a novel dielectric barrier discharge ionisation source for mass spectrometry.

PubMed

Fletcher, Carl; Sleeman, Richard; Luke, John; Luke, Peter; Bradley, James W

2018-03-01

The detection of explosives is of great importance, as is the need for sensitive, reliable techniques that require little or no sample preparation and short run times for high throughput analysis. In this work, a novel ionisation source is presented based on a dielectric barrier discharge (DBD). This not only affects desorption and ionisation but also forms an ionic wind, providing mass transportation of ions towards the mass spectrometer. Furthermore, the design incorporates 2 asymmetric alumina sheets, each containing 3 DBDs, so that a large surface area can be analysed. The DBD operates in ambient air, overcoming the limitation of other plasma-based techniques which typically analyse smaller surface areas and require solvents or gases. A range of explosives across 4 different functional groups was analysed using the DBD with low limits of detection for cyclotrimethylene trinitramine (RDX) (100 pg), pentaerythritol trinitrate (PETN) (100 pg), hexamethylene triperoxide diamide (HMTD) (1 ng), and trinitrotoluene (TNT) (5 ng). Detection was achieved without any sample preparation or the addition of reagents to facilitate adduct formation. Copyright © 2017 John Wiley & Sons, Ltd.

Ability of thermochemical calculation to treat organic peroxides

NASA Astrophysics Data System (ADS)

Osmont, Antoine; Baudin, Gérard; Genetier, Marc

2017-06-01

Since 3 years, the CEA Gramat is developing a new thermochemical code, called SIAME, funded by DGA to help French defense industry at conceiving new explosives compositions. It enables the calculation of CJ detonation and deflagration points and combustion of explosives. The accuracy of the code has been checked on several compositions containing PETN, RDX, HMX, TNT, NTO. The error on the velocity of detonation is 3%. To enlarge the domain of validity of the code, organic peroxides have been considered. It is known that thermochemical simulation is in failure regarding compounds as simple as hydrogen peroxide. The computed velocity of detonation is 5720 m/s when shock planar impact gives 6150 m/s. The same discrepancy is found for TATP, with a calculated value at 5870 m/s when 5290 has been measured. Detonation velocity of TATP has been measured at two different densities. These velocities agree with other published values. A closer look at the enthalpy of formation of TATP has revealed that it comes from an article of 1932. Ab initio computations have given a totally different value, leading to better agreement with experiment.

Polymyxin susceptibility testing, interpretative breakpoints and resistance mechanisms: An update.

PubMed

Bakthavatchalam, Yamuna Devi; Pragasam, Agila Kumari; Biswas, Indranil; Veeraraghavan, Balaji

2018-03-01

Emerging multidrug-resistant (MDR) nosocomial pathogens are a great threat. Polymyxins, an old class of cationic polypeptide antibiotic, are considered as last-resort drugs in treating infections caused by MDR Gram-negative bacteria. Increased use of polymyxins in treating critically ill patients necessitates routine polymyxin susceptibility testing. However, susceptibility testing both of colistin and polymyxin B (PMB) is challenging. In this review, currently available susceptibility testing methods are briefly discussed. The multicomponent composition of colistin and PMB significantly influences susceptibility testing. In addition, poor diffusion in the agar medium, adsorption to microtitre plates and the synergistic effect of the surfactant polysorbate 80 with polymyxins have a great impact on the performance of susceptibility testing methods This review also describes recently identified chromosomal resistance mechanisms, including modification of lipopolysaccharide (LPS) with 4-amino-4-deoxy-l-arabinose (L-Ara4-N) and phosphoethanolamine (pEtN) resulting in alteration of the negative charge, as well as the plasmid-mediated colistin resistance determinants mcr-1, mcr-1.2, mcr-2 and mcr-3. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

Excited state dynamics can be used to probe donor-acceptor distances for H-tunneling reactions catalyzed by flavoproteins.

PubMed

Hardman, Samantha J O; Pudney, Christopher R; Hay, Sam; Scrutton, Nigel S

2013-12-03

In enzyme systems where fast motions are thought to contribute to H-transfer efficiency, the distance between hydrogen donor and acceptor is a very important factor. Sub-ångstrom changes in donor-acceptor distance can have a large effect on the rate of reaction, so a sensitive probe of these changes is a vital tool in our understanding of enzyme function. In this study we use ultrafast transient absorption spectroscopy to investigate the photoinduced electron transfer rates, which are also very sensitive to small changes in distance, between coenzyme analog, NAD(P)H4, and the isoalloxazine center in the model flavoenzymes morphinone reductase (wild-type and selected variants) and pentaerythritol tetranitrate reductase (wild-type). It is shown that upon addition of coenzyme to the protein the rate of photoinduced electron transfer is increased. By comparing the magnitude of this increase with existing values for NAD(P)H4-FMN distances, based on charge-transfer complex absorbance and experimental kinetic isotope effect reaction data, we show that this method can be used as a sensitive probe of donor-acceptor distance in a range of enzyme systems. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Ambient diode laser desorption dielectric barrier discharge ionization mass spectrometry of nonvolatile chemicals.

PubMed

Gilbert-López, Bienvenida; Schilling, Michael; Ahlmann, Norman; Michels, Antje; Hayen, Heiko; Molina-Díaz, Antonio; García-Reyes, Juan F; Franzke, Joachim

2013-03-19

In this work, the combined use of desorption by a continuous wave near-infrared diode laser and ionization by a dielectric barrier discharge-based probe (laser desorption dielectric barrier discharge ionization mass spectrometry (LD-DBDI-MS)) is presented as an ambient ionization method for the mass spectrometric detection of nonvolatile chemicals on surfaces. A separation of desorption and ionization processes could be verified. The use of the diode laser is motivated by its low cost, ease of use, and small size. To achieve an efficient desorption, the glass substrates are coated at the back side with a black point (target point, where the sample is deposited) in order to absorb the energy offered by the diode laser radiation. Subsequent ionization is accomplished by a helium plasmajet generated in the dielectric barrier discharge source. Examples on the application of this approach are shown in both positive and negative ionization modes. A wide variety of multiclass species with low vapor pressure were tested including pesticides, pharmaceuticals and explosives (reserpine, roxithromycin, propazine, prochloraz, spinosad, ampicillin, dicloxacillin, enrofloxacin, tetracycline, oxytetracycline, erythromycin, spinosad, cyclo-1,3,5,7-tetramethylene tetranitrate (HMX), and cyclo-1,3,5-trimethylene trinitramine (RDX)). A comparative evaluation revealed that the use of the laser is advantageous, compared to just heating the substrate surface.

Selective detection of trace nitroaromatic, nitramine, and nitrate ester explosive residues using a three-step fluorimetric sensing process: a tandem turn-off, turn-on sensor.

PubMed

Sanchez, Jason C; Toal, Sarah J; Wang, Zheng; Dugan, Regina E; Trogler, William C

2007-11-01

Detection of trace quantities of explosive residues plays a key role in military, civilian, and counter-terrorism applications. To advance explosives sensor technology, current methods will need to become cheaper and portable while maintaining sensitivity and selectivity. The detection of common explosives including trinitrotoluene (TNT), cyclotrimethylenetrinitramine, cyclotetramethylene-tetranitramine, pentaerythritol tetranitrate, 2,4,6-trinitrophenyl-N-methylnitramine, and trinitroglycerin may be carried out using a three-step process combining "turn-off" and "turn-on" fluorimetric sensing. This process first detects nitroaromatic explosives by their quenching of green luminescence of polymetalloles (lambda em approximately 400-510 nm). The second step places down a thin film of 2,3-diaminonaphthalene (DAN) while "erasing" the polymetallole luminescence. The final step completes the reaction of the nitramines and/or nitrate esters with DAN resulting in the formation of a blue luminescent traizole complex (lambda(em) = 450 nm) providing a "turn-on" response for nitramine and nitrate ester-based explosives. Detection limits as low as 2 ng are observed. Solid-state detection of production line explosives demonstrates the applicability of this method to real world situations. This method offers a sensitive and selective detection process for a diverse group of the most common high explosives used in military and terrorist applications today.

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis.

PubMed

Moriwaki, Hiroshi; Koide, Remi; Yoshikawa, Ritsuko; Warabino, Yuya; Yamamoto, Hiroki

2013-04-01

The aim of this study is to investigate the potential of cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis 168 to adsorb rare earth ions. Freeze-dried cell powders prepared from both strains were used for the evaluation of adsorption ability for the rare earth ions, namely, La(III), Eu(III), and Tm(III). The rare earth ions were efficiently adsorbed onto powders of both wild-type strain (WT powder) and lipoteichoic acid-defective strain (∆LTA powder) at pH 3. The maximum adsorption capacities for Tm(III) by WT and ∆LTA powders were 43 and 37 mg g(-1), respectively. Removal (in percent) of Tm(III), La(III), and Eu(III) from aqueous solution by WT powder was greater than by ∆LTA powder. These results indicate that rare earth ions are adsorbed to functional groups, such as phosphate and carboxyl groups, of lipoteichoic acid. We observed coagulated ∆LTA powder in the removal of rare earth ions (1-20 mg L(-1)) from aqueous solution. In contrast, sedimentation of WT powder did not occur under the same conditions. This unique feature of ∆LTA powder may be caused by the difference of the distribution between lipoteichoic acid and wall teichoic acid. It appears that ∆LTA powder is useful for removal of rare earth ions by adsorption, because aggregation allows for rapid separation of the adsorbent by filtration.

The Application of Globular Water-Atomized Iron Powders for Additive Manufacturing by a LENS Technique

PubMed Central

Ziętala, Michał; Antolak-Dudka, Anna; Paserin, Vlad

2018-01-01

The water-atomized ATOMET 28, 1001, 4701, and 4801 powders, manufactured by Rio Tinto Metal Powders, were used for additive manufacturing by a laser engineered net shaping (LENS) technique. Their overall morphology was globular and rounded with a size distribution from about 20 to 200 µm. Only the ATOMET 28 powder was characterized by a strong inhomogeneity of particle size and irregular polyhedral shape of powder particles with sharp edges. The powders were pre-sieved to a size distribution from 40 to 150 µm before LENS processing. One particular sample—LENS-fabricated from the ATOMET 28 powder—was characterized by the largest cross-sectional (2D) porosity of 4.2% and bulk porosity of 3.9%, the latter determined by microtomography measurements. In contrast, the cross-sectional porosities of bulk, solid, nearly cubic LENS-fabricated samples from the other ATOMET powders exhibited very low porosities within the range 0.03–0.1%. Unexpectedly, the solid sample—LENS-fabricated from the reference, a purely spherical Fe 99.8 powder—exhibited a porosity of 1.1%, the second largest after that of the pre-sieved, nonspherical ATOMET 28 powder. Vibrations incorporated mechanically into the LENS powder feeding system substantially improved the flow rate vs. feeding rate dependence, making it completely linear with an excellent coefficient of fit, R2 = 0.99. In comparison, the reference powder Fe 99.8 always exhibited a linear dependence of the powder flow rate vs. feeding rate, regardless of vibrations. PMID:29783704

Synthesis and characterization of nanocrystalline Nd{sup 3+}-doped gadolinium scandium aluminum garnet powders by a gel-combustion method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Jing, E-mail: zlj007@126.com; Miao, Ju-hong; Xu, Lin-hua

2012-07-15

Graphical abstract: The graph shows the emission spectra (λ{sub ex} = 808 nm) of 1 at.% Nd:GSAG powders sintered at different temperatures for 3 h. Compared with the powder sintered at 900 °C, the PL intensity of the powder sintered at 1000 °C decreased significantly. The changes in the PL intensity should mainly due to the crystallinity and dispersion of the powders. Highlights: ► We synthesized Nd:GSAG nano-powders by gel-combustion method successfully. ► We analyzed the structure and the morphology of the heat-treated products. ► We studied the optical characteristics of Nd:GSAG nano-powders. -- Abstract: Nd{sup 3+}-doped gadolinium scandium aluminummore » garnet (Nd:GSAG) precursor was synthesized by a gel combustion method using metal nitrates and citric acid as raw materials. The structure and morphology of the precursor and the sintered powders were studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The results showed that the precursor transformed into pure GSAG polycrystalline phase at about 800 °C, and the powders sintered at 800–1000 °C were well-dispersed with average particle sizes in the range of 30–80 nm. Optical properties of Nd:GSAG nano-powders were characterized by using photoluminescence spectroscopy. The highest photoluminescence intensity was achieved for the powder sintered at 900 °C.« less

Micro structrual characterization and analysis of ball milled silicon carbide

NASA Astrophysics Data System (ADS)

Madhusudan, B. M.; Raju, H. P.; Ghanaraja., S.

2018-04-01

Mechanical alloying has been one of the prominent methods of powder synthesis technique in solid state involving cyclic deformation, cold welding and fracturing of powder particles. Powder particles in this method are subjected to greater mechanical deformation due to the impact of ball-powder-ball and ball-powder-container collisions that occurs during mechanical alloying. Strain hardening and fracture of particles decreases the size of the particles and creates new surfaces. The objective of this Present work is to use ball milling of SiC powder for different duration of 5, 10, 15 and 20 hours by High energy planetary ball milling machine and to evaluate the effect of ball milling on SiC powder. Micro structural Studies using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and EDAX has been investigated.

Multiple feed powder splitter

DOEpatents

Lewis, Gary K.; Less, Richard M.

2001-01-01

A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

Multiple feed powder splitter

DOEpatents

Lewis, Gary K.; Less, Richard M.

2002-01-01

A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

Particle morphology influence on mechanical and biocompatibility properties of injection molded Ti alloy powder.

PubMed

Gülsoy, H Özkan; Gülsoy, Nagihan; Calışıcı, Rahmi

2014-01-01

Titanium and Titanium alloys exhibits properties that are excellent for various bio-applications. Metal injection molding is a processing route that offers reduction in costs, with the added advantage of near net-shape components. Different physical properties of Titanium alloy powders, shaped and processed via injection molding can achieve high complexity of part geometry with mechanical and bioactivity properties, similar or superior to wrought material. This study describes that the effect of particle morphology on the microstructural, mechanical and biocompatibility properties of injection molded Ti-6Al-4V (Ti64) alloy powder for biomaterials applications. Ti64 powders irregular and spherical in shape were injection molded with wax based binder. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered under high vacuum. Metallographic studies were determined to densification and the corresponding microstructural changes. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. The results show that spherical and irregular powder could be sintered to a maximum theoretical density. Maximum tensile strength was obtained for spherical shape powder sintered. The tensile strength of the irregular shape powder sintered at the same temperature was lower due to higher porosity. Finally, mechanical tests show that the irregular shape powder has lower mechanical properties than spherical shape powder. The sintered irregular Ti64 powder exhibited better biocompatibility than sintered spherical Ti64 powder. Results of study showed that sintered spherical and irregular Ti64 powders exhibited high mechanical properties and good biocompatibility properties.

Rapid identification of pearl powder from Hyriopsis cumingii by Tri-step infrared spectroscopy combined with computer vision technology

NASA Astrophysics Data System (ADS)

Liu, Siqi; Wei, Wei; Bai, Zhiyi; Wang, Xichang; Li, Xiaohong; Wang, Chuanxian; Liu, Xia; Liu, Yuan; Xu, Changhua

2018-01-01

Pearl powder, an important raw material in cosmetics and Chinese patent medicines, is commonly uneven in quality and frequently adulterated with low-cost shell powder in the market. The aim of this study is to establish an adequate approach based on Tri-step infrared spectroscopy with enhancing resolution combined with chemometrics for qualitative identification of pearl powder originated from three different quality grades of pearls and quantitative prediction of the proportions of shell powder adulterated in pearl powder. Additionally, computer vision technology (E-eyes) can investigate the color difference among different pearl powders and make it traceable to the pearl quality trait-visual color categories. Though the different grades of pearl powder or adulterated pearl powder have almost identical IR spectra, SD-IR peak intensity at about 861 cm- 1 (v2 band) exhibited regular enhancement with the increasing quality grade of pearls, while the 1082 cm- 1 (v1 band), 712 cm- 1 and 699 cm- 1 (v4 band) were just the reverse. Contrastly, only the peak intensity at 862 cm- 1 was enhanced regularly with the increasing concentration of shell powder. Thus, the bands in the ranges of (1550-1350 cm- 1, 730-680 cm- 1) and (830-880 cm- 1, 690-725 cm- 1) could be exclusive ranges to discriminate three distinct pearl powders and identify adulteration, respectively. For massive sample analysis, a qualitative classification model and a quantitative prediction model based on IR spectra was established successfully by principal component analysis (PCA) and partial least squares (PLS), respectively. The developed method demonstrated great potential for pearl powder quality control and authenticity identification in a direct, holistic manner.

Microbial contamination of cosmetics and personal care items in Egypt--body lotions and talcum powders.

PubMed

Ashour, M S; Abdelaziz, A A; Hefni, H; el-Tayeb, O M

1989-06-01

We examined a total of 54 samples, including 18 body lotions and 36 talcum powders, for their total aerobic bacterial, coliform and fungal counts. We also carried out anaerobic bacterial counts for talcum powder as well as tests to detect some potentially hazardous bacteria in all tested samples. Talcum powders were more heavily contaminated with bacteria and fungi than body lotions. More than 40% of the tested body lotions contained no viable bacteria or less than 100 c.f.u./g. while all the talcum powders tested contained more than 100 c.f.u./g. Thirty per cent of the talcum powders were contaminated with 10(4) c.f.u./g. and none of the body lotions were contaminated to that extent. No coliforms were recovered from any of the body lotions, while 17% of the talcum powder examined contained coliforms in the range of 230-500 c.f.u./g. Staphylococcus spp. were detected in 18 samples of both talcum powders and body lotions, three of these Staphylococci were of the aureus type. Three samples of talcum powder contained E. coli, two samples contained Enterobacter agglomerans and one sample contained Citrobacter freundii. Seventy per cent of the body lotions showed no fungal counts, while 83% of the talcum powders examined were contaminated with fungi and most of the contaminated talcum powders contained more than 100 fungal cells/g. With regard to the anaerobic bacterial counts for talcum powders, 50% of the samples showed no counts while the other 50% contained less than 100 c.f.u./g. Four samples were contaminated with Clostridium perfringens, although C. tetani was not recovered from any of the samples.

Rapid identification of pearl powder from Hyriopsis cumingii by Tri-step infrared spectroscopy combined with computer vision technology.

PubMed

Liu, Siqi; Wei, Wei; Bai, Zhiyi; Wang, Xichang; Li, Xiaohong; Wang, Chuanxian; Liu, Xia; Liu, Yuan; Xu, Changhua

2018-01-15

Pearl powder, an important raw material in cosmetics and Chinese patent medicines, is commonly uneven in quality and frequently adulterated with low-cost shell powder in the market. The aim of this study is to establish an adequate approach based on Tri-step infrared spectroscopy with enhancing resolution combined with chemometrics for qualitative identification of pearl powder originated from three different quality grades of pearls and quantitative prediction of the proportions of shell powder adulterated in pearl powder. Additionally, computer vision technology (E-eyes) can investigate the color difference among different pearl powders and make it traceable to the pearl quality trait-visual color categories. Though the different grades of pearl powder or adulterated pearl powder have almost identical IR spectra, SD-IR peak intensity at about 861cm -1 (v 2 band) exhibited regular enhancement with the increasing quality grade of pearls, while the 1082cm -1 (v 1 band), 712cm -1 and 699cm -1 (v 4 band) were just the reverse. Contrastly, only the peak intensity at 862cm -1 was enhanced regularly with the increasing concentration of shell powder. Thus, the bands in the ranges of (1550-1350cm -1 , 730-680cm -1 ) and (830-880cm -1 , 690-725cm -1 ) could be exclusive ranges to discriminate three distinct pearl powders and identify adulteration, respectively. For massive sample analysis, a qualitative classification model and a quantitative prediction model based on IR spectra was established successfully by principal component analysis (PCA) and partial least squares (PLS), respectively. The developed method demonstrated great potential for pearl powder quality control and authenticity identification in a direct, holistic manner. Copyright © 2017. Published by Elsevier B.V.

Investigation of Microtubular Ceramic Structures

DTIC Science & Technology

1979-02-01

25 Experiments 05x - Excel ŗ-5 CAL" (Powder D). 25 Experiments 06x - Excel ŗ-5 CAL" (Powder D). 26 Experiments 07x - Stabilized Zirconia ( Powder E...an extremely fine particle size (- 0. 4 jim) for satisfactory sintering. With zirconia powder of this particle size, spherical aggregates formed...firm" packing pressure, sustained large additions (15 to--9 gm/cycle) occurred. Experiments 07x - Stabilized Zirconia ( Powder E) The 07x experiments

PLUTONIUM-HYDROGEN REACTION PRODUCT, METHOD OF PREPARING SAME AND PLUTONIUM POWDER THEREFROM

DOEpatents

Fried, S.; Baumbach, H.L.

1959-12-01

A process is described for forming plutonlum hydride powder by reacting hydrogen with massive plutonium metal at room temperature and the product obtained. The plutonium hydride powder can be converted to plutonium powder by heating to above 200 deg C.

Silane surface modification effects on the electromagnetic properties of phosphatized iron-based SMCs

NASA Astrophysics Data System (ADS)

Fan, Liang-Fang; Hsiang, Hsing-I.; Hung, Jia-Jing

2018-03-01

It is difficult to achieve homogeneous phosphatized iron powder dispersion in organic resins during the preparation of soft magnetic composites (SMCs). Inhomogeneous iron powder mixing in organic resins generally leads to the formation of micro-structural defects in SMCs and hence causes the magnetic properties to become worse. Phosphatized iron powder dispersion in organic resins can be improved by coating the phosphatized iron powder surfaces with a coupling agent. This study investigated the (3-aminopropyl) triethoxysilane (APTES) surface modification effects on the electromagnetic properties of phosphatized iron-based soft magnetic composites (SMCs). The results showed that the phosphatized iron powder surface can be modified using APTES to improve the phosphatized iron powder and epoxy resin compatibility and hence enhance phosphate iron powder epoxy mixing. The tensile strength, initial permeability, rated current under DC-bias superposition and magnetic loss in SMCs prepared using phosphatized iron powders can be effectively improved using APTES surface modification, which provides a promising candidate for power chip inductor applications.

Characterisation of spray dried soy sauce powders made by adding crystalline carbohydrates to drying carrier.

PubMed

Wang, Wei; Zhou, Weibiao

2015-02-01

This study aimed to reduce stickiness and caking of spray dried soy sauce powders by introducing a new crystalline structure into powder particles. To perform this task, soy sauce powders were formulated by using mixtures of cellulose and maltodextrin or mixtures of waxy starch and maltodextrin as drying carriers, with a fixed carrier addition rate of 30% (w/v) in the feed solution. The microstructure, crystallinity, solubility as well as stickiness and caking strength of all the different powders were analysed and compared. Incorporating crystalline carbohydrates in the drying carrier could significantly reduce the stickiness and caking strength of the powders when the ratio of crystalline carbohydrates to maltodextrin was above 1:5 and 1:2, respectively. X-ray Diffraction (XRD) results showed that adding cellulose or waxy starch could induce the crystallinity of powders. Differential Scanning Calorimetry (DSC) results demonstrated that the native starch added to the soy sauce powders did not fully gelatinize during spray drying. Copyright © 2014 Elsevier Ltd. All rights reserved.

Straightforward fabrication of black nano silica dusting powder for latent fingerprint imaging

NASA Astrophysics Data System (ADS)

Komalasari, Isna; Krismastuti, Fransiska Sri Herwahyu; Elishian, Christine; Handayani, Eka Mardika; Nugraha, Willy Cahya; Ketrin, Rosi

2017-11-01

Imaging of latent fingerprint pattern (aka fingermark) is one of the most important and accurate detection methods in forensic investigation because of the characteristic of individual fingerprint. This detection technique relies on the mechanical adherence of fingerprint powder to the moisture and oily component of the skin left on the surface. The particle size of fingerprint powder is one of the critical parameter to obtain excellent fingerprint image. This study develops a simple, cheap and straightforward method to fabricate Nano size black dusting fingerprint powder based on Nano silica and applies the powder to visualize latent fingerprint. The nanostructured silica was prepared from tetraethoxysilane (TEOS) and then modified with Nano carbon, methylene blue and sodium acetate to color the powder. Finally, as a proof-of-principle, the ability of this black Nano silica dusting powder to image latent fingerprint is successfully demonstrated and the results show that this fingerprint powder provides clearer fingerprint pattern compared to the commercial one highlighting the potential application of the nanostructured silica in forensic science.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, Raghunath; Blaugher, Richard D.

1995-01-01

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

Influence of short chain organic acids and bases on the wetting properties and surface energy of submicrometer ceramic powders.

PubMed

Neirinck, Bram; Soccol, Dimitri; Fransaer, Jan; Van der Biest, Omer; Vleugels, Jef

2010-08-15

The effect of short chained organic acids and bases on the surface energy and wetting properties of submicrometer alumina powder was assessed. The surface chemistry of treated powders was determined by means of Diffuse Reflectance Infrared Fourier Transform spectroscopy and compared to untreated powder. The wetting of powders was measured using a modified Washburn method, based on the use of precompacted powder samples. The geometric factor needed to calculate the contact angle was derived from measurements of the porous properties of the powder compacts. Contact angle measurements with several probe liquids before and after modification allowed a theoretical estimation of the surface energy based on the surface tension component theory. Trends in the surface energy components were linked to observations in infrared spectra. The results showed that the hydrophobic character of the precompacted powder depends on both the chain length and polar group of the modifying agent. Copyright 2010 Elsevier Inc. All rights reserved.

Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder

PubMed Central

Li, Jiaxiang; Li, Yunping; Wang, Zhongchang; Bian, Huakang; Hou, Yuhang; Wang, Fenglin; Xu, Guofu; Liu, Bin; Liu, Yong

2016-01-01

The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service. PMID:28004839

Device for preparing combinatorial libraries in powder metallurgy.

PubMed

Yang, Shoufeng; Evans, Julian R G

2004-01-01

This paper describes a powder-metering, -mixing, and -dispensing mechanism that can be used as a method for producing large numbers of samples for metallurgical evaluation or electrical or mechanical testing from multicomponent metal and cermet powder systems. It is designed to make use of the same commercial powders that are used in powder metallurgy and, therefore, to produce samples that are faithful to the microstructure of finished products. The particle assemblies produced by the device could be consolidated by die pressing, isostatic pressing, laser sintering, or direct melting. The powder metering valve provides both on/off and flow rate control of dry powders in open capillaries using acoustic vibration. The valve is simple and involves no relative movement, avoiding seizure with fine powders. An orchestra of such valves can be arranged on a building platform to prepare multicomponent combinatorial libraries. As with many combinatorial devices, identification and evaluation of sources of mixing error as a function of sample size is mandatory. Such an analysis is presented.

Identification of mothball powder composition by float tests and melting point tests.

PubMed

Tang, Ka Yuen

2018-07-01

The aim of the study was to identify the composition, as either camphor, naphthalene, or paradichlorobenzene, of mothballs in the form of powder or tiny fragments by float tests and melting point tests. Naphthalene, paradichlorobenzene and camphor mothballs were blended into powder and tiny fragments (with sizes <1/10 of the size of an intact mothball). In the float tests, the mothball powder and tiny fragments were placed in water, saturated salt solution and 50% dextrose solution (D50), and the extent to which they floated or sank in the liquids was observed. In the melting point tests, the mothball powder and tiny fragments were placed in hot water with a temperature between 53 and 80 °C, and the extent to which they melted was observed. Both the float and melting point tests were then repeated using intact mothballs. Three emergency physicians blinded to the identities of samples and solutions visually evaluated each sample. In the float tests, paradichlorobenzene powder partially floated and partially sank in all three liquids, while naphthalene powder partially floated and partially sank in water. Naphthalene powder did not sink in D50 or saturated salt solution. Camphor powder floated in all three liquids. Float tests identified the compositions of intact mothball accurately. In the melting point tests, paradichlorobenzene powder melted completely in hot water within 1 min while naphthalene powder and camphor powder did not melt. The melted portions of paradichlorobenzene mothballs were sometimes too small to be observed in 1 min but the mothballs either partially or completely melted in 5 min. Both camphor and naphthalene intact mothballs did not melt in hot water. For mothball powder, the melting point tests were more accurate than the float tests in differentiating between paradichlorobenzene and non-paradichlorobenzene (naphthalene or camphor). For intact mothballs, float tests performed better than melting point tests. Float tests can identify camphor mothballs but melting point tests cannot. We suggest melting point tests for identifying mothball powder and tiny fragments while float tests are recommended for intact mothball and large fragments.

L-Leucine as an excipient against moisture on in vitro aerosolization performances of highly hygroscopic spray-dried powders.

PubMed

Li, Liang; Sun, Siping; Parumasivam, Thaigarajan; Denman, John A; Gengenbach, Thomas; Tang, Patricia; Mao, Shirui; Chan, Hak-Kim

2016-05-01

L-Leucine (LL) has been widely used to enhance the dispersion performance of powders for inhalation. LL can also protect powders against moisture, but this effect is much less studied. The aim of this study was to investigate whether LL could prevent moisture-induced deterioration in in vitro aerosolization performances of highly hygroscopic spray-dried powders. Disodium cromoglycate (DSCG) was chosen as a model drug and different amounts of LL (2-40% w/w) were added to the formulation, with the aim to explore the relationship between powder dispersion, moisture protection and physicochemical properties of the powders. The powder formulations were prepared by spray drying of aqueous solutions containing known concentrations of DSCG and LL. The particle sizes were measured by laser diffraction. The physicochemical properties of fine particles were characterized by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic vapor sorption (DVS). The surface morphology and chemistry of fine particles were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In vitro aerosolization performances were evaluated by a next generation impactor (NGI) after the powders were stored at 60% or 75% relative humidity (RH), and 25°C for 24h. Spray-dried (SD) DSCG powders were amorphous and absorbed 30-45% (w/w) water at 70-80% RH, resulting in deterioration in the aerosolization performance of the powders. LL did not decrease the water uptake of DSCG powders, but it could significantly reduce the effect of moisture on aerosolization performances. This is due to enrichment of crystalline LL on the surface of the composite particles. The effect was directly related to the percentage of LL coverage on the surface of particles. Formulations having 61-73% (molar percent) of LL on the particle surface (which correspond to 10-20% (w/w) of LL in the bulk powders) could minimize moisture-induced deterioration in the aerosol performance. In conclusion, particle surface coverage of LL can offer short-term protection against moisture on dispersion of hygroscopic powders. Copyright © 2016 Elsevier B.V. All rights reserved.

Injection molding ceramics to high green densities

NASA Technical Reports Server (NTRS)

Mangels, J. A.; Williams, R. M.

1983-01-01

The injection molding behavior of a concentrated suspension of Si powder in wax was studied. It was found that the injection molding behavior was a function of the processing techniques used to generate the powder. Dry ball-milled powders had the best molding behavior, while air classified and impact-milled powders demonstrated poorer injection moldability. The relative viscosity of these molding batches was studied as a function of powder properties: distribution shape, surface area, packing density, and particle morphology. The experimental behavior, in all cases, followed existing theories. The relative viscosity of an injection molding composition composed of dry ball-milled powders could be expressed using Farris' relation.

Synthesis of nanostructured vanadium powder by high-energy ball milling: X-ray diffraction and high-resolution electron microscopy characterization

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran

2016-10-01

Vanadium metal powders, ball milled with different surfactants viz., stearic acid, KCl and NaCl, have been studied by X-ray diffraction and transmission electron microscopy. The surfactants alter the microstructural and morphological characteristics of the powders. Ball milling with stearic acid results in solid-state amorphization, while powders milled with KCl yield vanadium-tungsten carbide nanocomposite mixtures. NaCl proved to be an excellent surfactant for obtaining nanostructured fusion-grade vanadium powders. In order to understand the reaction mechanism behind any interstitial addition in the ball-milled powders, CHNOS analysis was performed.

Vacuum Powder Injector

NASA Technical Reports Server (NTRS)

Working, Dennis C.

1991-01-01

Method developed to provide uniform impregnation of bundles of carbon-fiber tow with low-solubility, high-melt-flow polymer powder materials to produce composite prepregs. Vacuum powder injector expands bundle of fiber tow, applies polymer to it, then compresses bundle to hold powder. System provides for control of amount of polymer on bundle. Crystallinity of polymer maintained by controlled melt on takeup system. All powder entrapped, and most collected for reuse. Process provides inexpensive and efficient method for making composite materials. Allows for coating of any bundle of fine fibers with powders. Shows high potential for making prepregs of improved materials and for preparation of high-temperature, high-modulus, reinforced thermoplastics.

Comparison of Glass Powder and Fly Ash Effect on the Fresh Properties of Self-Compacting Mortars

NASA Astrophysics Data System (ADS)

Öznur Öz, Hatice; Erhan Yücel, Hasan; Güneş, Muhammet

2017-10-01

This study is aimed to determine effects of glass powder on fresh properties of self-compacting mortars. Self-compacting mortars incorporating glass powder (SCMGPs) were designed with a water/binder ratio of 0.40 and a total binder content of 550 kg/m3. At first, the control mixture was produced with 20% fly ash and % 80 cement of the total binder content without using the glass powder. Then, glass powder was used in the proportions 5%, 10%, 15% and 20% instead of fly ash in the mortars. Mini-slump flow and mini-v funnel tests experimentally investigated on SCMGPs to compare the effect of fly ash and glass powder. With increasing the amount of glass powder used in SCMGPs increased the amount of superplasticizer used to obtain the desired mini-slump flow diameter. So, the use of glass powder reduced the flow ability of SCMGPs in comparison to fly ash. Additionally, the compressive strength and flexural strength of the mortar mixtures were determined at the 28th day. The test results indicated that the mechanical characteristics of SCMGPs improved when the fly ash was replaced with glass powder in SCMGPs.

Facile synthesis of multi-shell structured binary metal oxide powders with a Ni/Co mole ratio of 1:2 for Li-Ion batteries

NASA Astrophysics Data System (ADS)

Choi, Seung Ho; Park, Sun Kyu; Lee, Jung-Kul; Kang, Yun Chan

2015-06-01

Multi-shell structured binary transition metal oxide powders with a Ni/Co mole ratio of 1:2 are prepared by a simple spray drying process. Precursor powder particles prepared by spray drying from a spray solution of citric acid and ethylene glycol have completely spherical shape, fine size, and a narrow size distribution. The precursor powders turn into multi-shell powders after a post heat-treatment at temperatures between 250 and 800 °C. The multi-shell structured powders are formed by repeated combustion and contraction processes. The multi-shell powders have mixed crystal structures of Ni1-xCo2O4-x and NiO phases regardless of the post-treatment temperature. The reversible capacities of the powders post-treated at 250, 400, 600, and 800 °C after 100 cycles are 584, 913, 808, and 481 mA h g-1, respectively. The low charge transfer resistance and high lithium ion diffusion rate of the multi-shell powders post-treated at 400 °C with optimum grain size result in superior electrochemical properties even at high current densities.

Effect of drying environment on grain size of titanium dioxide nano-powder synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Zandi, Pegah; Hosseini, Elham; Rashchi, Fereshteh

2018-01-01

Titanium dioxide Nano powder has been synthesized from titanium isopropoxide (TTIP) in chloride media by sol-gel method. In this research, the effect of the drying environment, from air to oven drying at 100 °C, calcination time and temperature on nano TiO2 grain size was investigated. The synthesized powder was analyzed by x-ray diffraction and scanning electron microscope. Based on the results, the powder has been crystallized in anatase and rutile phases, due to different calcination temperatures. At temperatures above 600 °C, the Titanium dioxide nano powder has been crystallized as rutile. The crystalline structure of titanium dioxide nano powder changed because of the different calcination temperatures and time applied. The average particle size of the powder dried in air was larger than the powder dried in oven. The minimum particle size of the powder dried in air was 50 nm and in the oven was 9 nm, observed and calculated Williamson-Hall equation. All in all, with overall increasing of calcination time and temperature the grain size increased. Moreover, in the case of temperature, after a certain temperature, the grain size became constant and didn't change significantly.

Synthesis and characterization of nanocrystalline Al 2024-B4C composite powders by mechanical alloying

NASA Astrophysics Data System (ADS)

Varol, T.; Canakci, A.

2013-06-01

In the present work, the effect of milling parameters on the morphology and microstructure of nanostructure Al2024-B4C composite powders obtained by mechanical alloying (MA) was studied. The effects of milling time and B4C content on the morphology, microstructure and particle size of nanostructure Al2024-B4C composite powders have been investigated. Different amounts of B4C particles (0, 5, 10 and 20 wt.%) were mixed with Al2024 powders and milled in a planetary ball mill for 30, 60, 120, 300, 420 and 600 min. Al 2024-B4C composite powders were characterized using a scanning electron microscope (SEM), laser particle-size analyzer, X-ray diffraction analysis (XRD) and the Vickers microhardness test. The results showed that the nanostructure Al2024-B4C composite powders were produced when they were milled for 600 min. The size of composite powder in the milled powder mixture was affected by the milling time and content of B4C particles. Moreover, it was observed that when MA reached a steady state, the properties of composite powders were stabilized.

Free flowing and cohesive powders agitation in a cylindrical convective blender- kinetics experiments and Markov chain modelling

NASA Astrophysics Data System (ADS)

Legoix, Léonard; Milhé, Mathieu; Gatumel, Cendrine; Berthiaux, Henri

2017-06-01

An original methodology for studying powder flow in a cylindrical convective blender has been developed. A free-flowing and a cohesive powder were studied, at a fixed stirring speed, in rolling regime. For both powders, three apparent flow mechanisms were evidenced: convection in the volume swept by the blades, diffusion/shearing between the agitated zone and the stagnant one, as well as in the stagnant zone itself, and avalanches at the powder bed surface between agitated and stagnant zones. After defining six zones in the blender, tracing experiments were carried out by placing appropriate tracers in different starting zones and sampling the whole bed at different stirring times, which lead to mixing kinetics of the powders into themselves. A Markov chains model of the blender allowed the quantification of the three mechanisms respective magnitude by fitting the experimental data. This simple model has a good agreement with the free-flowing powder data, but is not able to represent well the observations for the cohesive powder. Bed consolidation should probably be taken into account for this kind of powders and thus a linear Markov model is not sufficient.

Particle Size Effects on Flow Properties of PS304 Plasma Spray Feedstock Powder Blend

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; DellaCorte, Christopher; Eylon, Daniel

2002-01-01

The effects of BaF2-CaF2 particle size and size distribution on PS304 feedstock powder flowability have been investigated. Angular BaF2-CaF2 eutectic powders were produced by comminution and classified by screening to obtain 38 to 45 microns 45 to 106 microns, 63 to 106 microns, 45 to 53 microns, 63 to 75 microns, and 90 to 106 microns particle size distributions. The fluorides were added incrementally from 0 to 10 wt% to the other powder constituents of the PS304 feedstock: nichrome, chromia, and silver powders. The flow rate of the powder blends decreased linearly with increasing concentration of the fluorides. Flow was degraded with decreasing BaF2-CaF2 particle size and with increasing BaF2-CaF2 particle size distribution. A semiempirical relationship is offered to describe the PS304 powder blend flow behavior. The Hausner Ratio confirmed the funnel flow test results, but was slightly less sensitive to differences in BaF2-CaF2 particle size and size distribution. These findings may have applicability to other powders that do not flow easily, such as ceramic powders.

Prediction of the Effective Thermal Conductivity of Powder Insulation

NASA Astrophysics Data System (ADS)

Jin, Lingxue; Park, Jiho; Lee, Cheonkyu; Jeong, Sangkwon

The powder insulation method is widely used in structural and cryogenic systems such as transportation and storage tanks of cryogenic fluids. The powder insulation layer is constructed by small particle powder with light weight and some residual gas with high porosity. So far, many experiments have been carried out to test the thermal performance of various kinds of powder, including expanded perlite, glass microspheres, expanded polystyrene (EPS). However, it is still difficult to predict the thermal performance of powder insulation by calculation due to the complicated geometries, including various particle shapes, wide powder diameter distribution, and various pore sizes. In this paper, the effective thermal conductivity of powder insulation has been predicted based on an effective thermal conductivity calculationmodel of porous packed beds. The calculation methodology was applied to the insulation system with expanded perlite, glass microspheres and EPS beads at cryogenic temperature and various vacuum pressures. The calculation results were compared with previous experimental data. Moreover, additional tests were carried out at cryogenic temperature in this research. The fitting equations of the deformation factor of the area-contact model are presented for various powders. The calculation results show agood agreement with the experimental results.

Thermal conductivity model for powdered materials under vacuum based on experimental studies

NASA Astrophysics Data System (ADS)

Sakatani, N.; Ogawa, K.; Iijima, Y.; Arakawa, M.; Honda, R.; Tanaka, S.

2017-01-01

The thermal conductivity of powdered media is characteristically very low in vacuum, and is effectively dependent on many parameters of their constituent particles and packing structure. Understanding of the heat transfer mechanism within powder layers in vacuum and theoretical modeling of their thermal conductivity are of great importance for several scientific and engineering problems. In this paper, we report the results of systematic thermal conductivity measurements of powdered media of varied particle size, porosity, and temperature under vacuum using glass beads as a model material. Based on the obtained experimental data, we investigated the heat transfer mechanism in powdered media in detail, and constructed a new theoretical thermal conductivity model for the vacuum condition. This model enables an absolute thermal conductivity to be calculated for a powder with the input of a set of powder parameters including particle size, porosity, temperature, and compressional stress or gravity, and vice versa. Our model is expected to be a competent tool for several scientific and engineering fields of study related to powders, such as the thermal infrared observation of air-less planetary bodies, thermal evolution of planetesimals, and performance of thermal insulators and heat storage powders.

Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

NASA Astrophysics Data System (ADS)

Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

2018-03-01

In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

Compressive Deformation Behavior of Open-Cell Cu-Zn-Al Alloy Foam Made Through P/M Route Using Mechanically Alloyed Powder

NASA Astrophysics Data System (ADS)

Barnwal, Ajay Kumar; Mondal, D. P.; Kumar, Rajeev; Prasanth, N.; Dasgupta, R.

2018-03-01

Cu-Zn-Al foams of varying porosity fractions using mechanical alloyed powder have been made through powder metallurgy route. Here, NH4 (HCO3) was used as a space holder. Mechanically alloyed Cu-Zn-Al is made using a planetary ball mill taking the ratio of Cu/Zn/Al = 70:25:5 (by weight ratio). The ball/powder ratios were varied in the four ranges 10:1, 15:1, 20:1, and 25:1. Green compacts of milled powder and space holder samples were sintered at three stages at three different temperatures 350, 550, and 850 °C for 1 h at each stage. The crystalline size and particle size as a function of ball/powder ratios were examined. The compressive deformation responses of foams are varied with relative density and the ball/powder ratio. The plateau stress and energy absorption of these foams increase with an increase in relative density but decreases with increase in ball/powder ratio, even though crystalline size decreases. This has further been explained on the basis of particle morphology as a function of ball/powder ratio.