Overview of Nanoscale Energetic Materials Research at Los Alamos

2005 ◽  
Vol 896 ◽  
Author(s):  
Steven F. Son ◽  
Timothy Foley ◽  
V. Eric Sanders ◽  
Alan Novak ◽  
Douglas Tasker ◽  
...  
Keyword(s):  
Energetic Materials ◽  
Chemical Potential ◽  
Optical Measurements ◽  
Los Alamos ◽  
Gas Gun ◽  
Front Position ◽  
Materials Research ◽  
Ignition And Combustion ◽  
Peak Pressures ◽  
First Time

AbstractMetastable Intermolecular Composite (MIC) materials are comprised of a mixture of oxidizer and fuel with particle sizes in the nanometer range. Characterizing their ignition and combustion is an ongoing effort at Los Alamos. In this paper we will present some recent studies at Los Alamos aimed at developing a better understanding of ignition and combustion of MIC materials. Ignition by impact has been studied using a laboratory gas gun using nano-aluminum (Al) and nano-tantalum (Ta) as the reducing agent and bismuth (III) oxide (Bi2O3) as the oxidant. As expected from the chemical potential, the Al containing composites gave higher peak pressures. It was found, for the Al/Bi2O3 system, that impact velocity under observed conditions plays no role in the pressure output until approximately 100 m/s, below which speed, impact energy is insufficient to ignite the reaction. This makes the experiment more useful in evaluating the reactive performance. Replacing the atmosphere on impact with an inert gas reduced both the amount of light produced and the realized peak pressure. The combustion of low-density MIC powders has also been studied. To better understand the reaction mechanisms of burning MIC materials, dynamic electrical conductivity measurements have been performed on a MIC material for the first time. Simultaneous optical measurements of the wave front position have shown that the reaction and conduction fronts are coincident within 160 μm.

scholarly journals Taming nitroformate through encapsulation with nitrogen-rich hydrogen-bonded organic frameworks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jichuan Zhang ◽  
Yongan Feng ◽  
Richard J. Staples ◽  
Jiaheng Zhang ◽  
Jean’ne M. Shreeve
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Energetic Materials ◽  
Decomposition Temperature ◽  
High Oxygen Content ◽  
The Poor ◽  
Simple Preparation ◽  
First Time ◽  
Hydrogen Bonded

AbstractOwing to its simple preparation and high oxygen content, nitroformate [−C(NO2)3, NF] is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.

9. pH Triggered Molecular Tweezers for Drug Delivery Applications

2016 ◽  
Author(s):  
Caitlin Miron
Keyword(s):  
Drug Delivery ◽  
Targeted Delivery ◽  
Chemical Potential ◽  
Cancer Drug ◽  
Molecular Tweezers ◽  
Binding Domains ◽  
Non Covalent Interactions ◽  
Molecular Tweezer ◽  
First Time ◽  
Covalent Interactions

Molecular tweezers are simple synthetic receptors that are generally composed of two binding domains connected by a spacer group. The non-covalent interactions that occur between the tweezer and its substrate are usually reversible, which facilitates the release of the bound substrate at a target site when triggered by a stimulus such as light, temperature, pH,] or change in chemical potential. In the field of cancer research, one strategy for targeting drug delivery relies on the pH drop in cancerous tissues compared to healthy tissues. We recently showed, for the first time, that it is possible to use pH to tune the binding affinity of molecular tweezers for substrates such as the cancer drug MitoxantroneTM. The molecular tweezer switches conformation from a closed (binding) state to an open (release) state upon acidification. As a result, the targeted delivery of MitoxantroneTM is achieved. This proof of concept shows that molecular tweezers are promising tools for selective drug delivery.

Spatio-Temporal Development of Supercavitation Over an Impulsively Launched Projectile

2006 ◽  
Author(s):  
C. J. Weiland ◽  
P. P. Vlachos
Keyword(s):  
High Speed ◽  
Temporal Development ◽  
Two Phase ◽  
Time Resolved ◽  
Gas Gun ◽  
Supercavitating Flow ◽  
Image Velocimetry ◽  
Spatio Temporal ◽  
Asymmetric Vortices ◽  
First Time

Supercavitation inception and formation was studied over blunt projectiles. The projectiles were fired using a gas gun method. In this method, projectiles are launched under the action of expanding detonation gases. Both qualitative and quantitative optical flow diagnostics using high speed digital imaging were used to analyze the spatio-temporal development of the supercavitating flow. For the first time, quantification of the supercavitation was achieved using Time Resolved Digital Particle Image Velocimetry (TRDPIV) detailing the two phase flow field surrounding the translating projectiles and the gas vapor bubble. Experimental results indicate that the supercavity forms at the aft end of the projectile and travels forward along the direction of projectile travel. The impulsive start of the projectile generates two asymmetric vortices which are shed from the blunt nose of the projectile. The vortices interact with the moving cavity and subsequently deform. This interaction is believed to directly contribute to the instabilities in the flight path.

The thermochemistry and reaction pathways of energetic material decomposition and combustion

1992 ◽  
Vol 339 (1654) ◽  
pp. 365-376 ◽  
Keyword(s):  
Condensed Phase ◽  
Energetic Materials ◽  
Energetic Material ◽  
Theoretical Method ◽  
Chemical Processes ◽  
Reaction Pathways ◽  
Quantum Chemical Methods ◽  
Solvation Energies ◽  
Moller Plesset ◽  
Ignition And Combustion

The chemical processes involved in the decomposition and combustion of energetic materials have been investigated theoretically using quantum chemical methods to determine the thermochemistry and reaction pathways. The Bond-Additivity-Corrected Moller-Plesset fourth-order perturbation theory method (BAC-MP4) has been used to determine heats of formation and free energies of reaction intermediates of decomposition and combustion. In addition, the BAC-MP4 method has been used to determine reaction pathways involving these intermediates. A theoretical method for calculating solvation energies has been developed to treat the non-idealities of high pressure and the condensed phase. The resulting chemical processes involving decomposition, ignition and combustion are presented for nitramines and nitromethane. Differences in decomposition mechanisms for the condensed phase and gas phase are discussed. In addition, we discuss the effects that amines can have on the initial stages of condensed-phase nitromethane decomposition. Bond dissociation energies for nitro-triazoles are compared with those of other nitro compounds.

scholarly journals ESPLORANDO “FLATLANDIA”: DAL GRAFENE ALLA SCOPERTA DI NUOVI MATERIALI BI-DIMENSIONALI

2020 ◽  
Author(s):  
Francesco Tumino
Keyword(s):  
Materials Science ◽  
2D Materials ◽  
Single Layer ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Bulk Materials ◽  
Molecular Sensing ◽  
Novel Technologies ◽  
Materials Research ◽  
First Time

The development of nanotechnology has encouraged the research of new nanomaterials for innovative applications. In 2004, the production and study of graphene — that is a single layer of carbon atoms — showed, for the first time, the extraordinary properties of this material and opened the way to the exploration of the so-called two-dimensional (2D) materials. Since then, several 2D materials have been produced and studied, revealing properties and behaviours, in general, very different from those of corresponding bulk materials. Research on 2D materials is nowadays one of the most active and promising fields of materials science, which is setting the basis for the development of novel technologies, such as in electronics, optoelectronics, energy and molecular sensing. In this paper, some important aspects of the study of 2D materials will be introduced — such as the synthesis methodologies and characterization techniques — and some of their properties will be shown, with the support of recent experimental results of scanning tunneling microscopy (STM) investigations.

scholarly journals TRANS4: a new coupled electron/proton transport code – comparison to observations above Svalbard using ESR, DMSP and optical measurements

2007 ◽  
Vol 25 (3) ◽  
pp. 661-673 ◽  
Author(s):  
C. Simon ◽  
J. Lilensten ◽  
J. Moen ◽  
J. M. Holmes ◽  
Y. Ogawa ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Kinetic Equations ◽  
Optical Measurements ◽  
Electron Densities ◽  
Data Set ◽  
Spectral Line Profile ◽  
Proton Precipitation ◽  
New Feature ◽  
First Time ◽  
Meteorological Satellite

Abstract. We present for the first time a numerical kinetic/fluid code for the ionosphere coupling proton and electron effects. It solves the fluid transport equations up to the eighth moment, and the kinetic equations for suprathermal particles. Its new feature is that for the latter, both electrons and protons are taken into account, while the preceding codes (TRANSCAR) only considered electrons. Thus it is now possible to compute in a single run the electron and ion densities due to proton precipitation. This code is successfully applied to a multi-instrumental data set recorded on 22 January 2004. We make use of measurements from the following set of instruments: the Defence Meteorological Satellite Program (DMSP) F-13 measures the precipitating particle fluxes, the EISCAT Svalbard Radar (ESR) measures the ionospheric parameters, the thermospheric oxygen lines are measured by an all-sky camera and the Hα line is given by an Ebert-Fastie spectrometer located at Ny-Ålesund. We show that the code computes the Hα spectral line profile with an excellent agreement with observations, providing some complementary information on the physical state of the atmosphere. We also show the relative effects of protons and electrons as to the electron densities. Computed electron densities are finally compared to the direct ESR measurements.

Thermal Conductiviy of type I and II Clathrate Compounds

2000 ◽  
Vol 626 ◽  
Author(s):  
G.S. Nolas ◽  
J.L. Cohn ◽  
M. Kaeser ◽  
T.M. Tritt
Keyword(s):  
Thermal Conductivity ◽  
Type I ◽  
Lattice Structures ◽  
Type Ii ◽  
Clathrate Compounds ◽  
Materials Research ◽  
Small Band ◽  
Semiconducting Compounds ◽  
First Time ◽  
Type Crystal

ABSTRACTCompounds with clathrate-hydrate type crystal lattice structures are currently of interest in thermoelectric materials research. This is due to the fact that semiconducting compounds can be synthesized with varying doping levels while possessing low, even ‘glass-like’, thermal conductivity. Up to now most of the work has focused on type I Si and Ge clathrates. Sn-clathrates however are viewed as having the greatest potential for thermoelectric cooling applications due to the larger mass of Sn and the expected small band-gap, as compared to Si and Ge clathrates. Transport properties on type I Sn-clathrates has only recently been reported [1–3]. In this report we present ongoing experimental research on both type I and II clathrates with an emphasis on the thermal transport of these novel materials. We present thermal conductivity data Si-Ge and Ge-Sn alloys as well as on a type II Ge clathrate for the first time, and compare these data to that of other clathrate compounds.

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