bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relationship between BAM Friction and Rotary Friction sensitiveness data for high explosives
Authors: Wharton R. K. , Chapman D. 
Published: May 2005

AbstractIn this short paper we report the relationship between friction sensitiveness data for high explosives obtained using the BAM friction and Rotary friction test methods. Although both methods can be used in evaluating safety in transport, in other hazard assessments only the BAM test is specified. The results of this study could therefore have significance in reducing the burden of additional testing in those cases where Rotary friction data are already available.
Modification of Pyrotechnic formulations to aid recovery, recycling and demilitarization
Authors: Akhavan J. , Grose I. , Rabin S. 
Published: May 2005

AbstractFollowing the International Treaty held in London and Oslo in 1972 and its amendment in Paris in 1992 on banning the dumping of hazardous and toxic waste at sea, large stockpiles of unwanted munition are now awaiting disposal. Public awareness, environmental concern and legislation are preventing the disposal of this explosive waste by landfill, detonation and open pit burning. One solution to this dilemma is to recover the waste from the containers and recycle or dispose of the waste in an environmentally sensitive manner.Preliminary investigations have been conducted at Cranfield University in developing explosive compositions which can be safely recovered and recycled. Pyrotechnic compositions were prepared containing water soluble binders and pressed into pellets. Performance and sensitivity tests were carried out on the pellets. Inclusion of water soluble binders into pyrotechnic compositions did not have any detrimental effect on their performance. However, there was a 33% reduction in the Figure of Insensitiveness (F of I) in all cases except for the composition containing Dextrin. This had a similar F of I to the control pyrotechnic composition. The pellets containing Dextrin were immersed in water. 97% of the pyrotechnic components were successfully recovered from the water by filtration and recrystallization. The recovered components were recycled into new pyrotechnic compositions which performed just as well as the original composition. The results from this preliminary investigation show that recovery and recycling of pyrotechnic components is feasible for compositions containing water soluble binders.
Rocket Propellants with Reduced Smoke and High Burning Rates
Authors: Menke Klaus , Eisele Siegfried 
Published: May 2005

AbstractRocket propellants with reduced smoke and high burning rates recommend themselves for use in a rocket motor for high accelerating tactical missiles. They serve for an improved camouflage on the battle field and may enable guidance control due to the higher transmission of their rocket plume compared to traditional aluminized composite propellants.In this contribution the material based ranges of performance and properties of three non aluminized rocket propellants will be introduced and compared to each other. The selected formulations based on AP/HTPB; AP/PU/TMETN and AP/HMX/GAP/TMETN have roughly the same specific impulse of ISP = 2430 Ns/kg at 70:1 expansion ratio. The burning rates in the pressure range from 10–18 MPa vary from to 26–33 mm/s for the AP/HTPB propellant, 52–68 mm/s for the formulation based on AP/PU/TMETN and 28–39 mm/s for the propellant based on AP/HMX/GAP. With 58% and 20% AP‐contents the propellants with nitrate ester plasticizers create a much smaller secondary signature than the AP/HTPB representative containing 86% AP. Their disadvantage, however, is the connection of high performance to a high level of energetic plasticizer. For this reason, the very fast burning propellant based on AP/PU/TMETN is endowed with a low elastic modulus and is limited to a grain configuration which isn't exposed too much to the fast and turbulent airstream. The mechanical properties of the AP/HMX/GAP‐propellant are as good or better as those of the AP/HTPB propellant. The first one exhibits the same performance and burn rates as the composite representative but produces only one fifth of HCl exhaust. For this reason it is recommended for missile applications, which must have high accelerating power together with a significantly reduced plume signature and smoke production.
Fast electrochemical Detection of Nitro‐ and Aminoaromates in Soils and Liquids
Authors: Krausa Michael , Doll Johannes , Schorb Klaus , Böke Winfried , Hambitzer Günter 
Published: May 2005

AbstractThe land sites of former explosives factories as well as troop exercise areas are frequently contaminated by 2,4,6‐Trinitrotoluene (TNT). As decontamination approaches, a direct on‐site measurement is necessary for a risk estimation. In contrast to ordinary analytics done in laboratories the employed methods are required to be fast and inexpensive. Additionally, they should be highly selective and sensitive. Up to now cyclic voltammetry is seldom used as an electrochemical method in the sensoric field. The presented new sensorsystem for the detection of TNT based on cyclic voltammetry fulfills the demands mentioned above.
Development of Gas Generators for Fire Extinguishing
Authors: Ebeling Hans , Schmid Helmut , Eisenreich Norbert , Weiser Volker 
Published: May 2005

AbstractGas producing materials are widely used in military or space applications as solid rocket and gun propellants. The chemical formulations of these propellants cannot be directly transferred to other applications as their product gases are optimized on high power, producing high amounts of CO and toxic trace constituents not acceptable in industrial applications.Beneath small scale applications in inflating bag boats or ejecting pilots of aircrafts etc. the gas generators for airbag inflation became a standard equipment of cars and improved safety of drivers and passengers substantially.Recently, systematic investigations started to realize the idea of using gases or aerosols produced by solid energetic or pyrotechnique materials for fire extinguishing. The actually introduced chemical gas generator formulations are based on the experience of pyrotechnics and solid propellants. Sodium azide and nitrocellulose containing mixtures cover most requirements on mass products. Despite their high level of technical development both formulations exhibit strong disadvantages.The work reported considers organic formulations for fire extinguishing, which produce gases composed of N2 and CO2. The gasgenerants described consist of non‐toxic chemicals including fuel, oxidant, catalyst and cooling agent for thermal process control. The formulations show higher gas output per mass, can be recycled environmentally friendly and are of low costs. The results comprise thermochemical properties governing the time dependent gas output, characterization of the constituents and trace species of the product gas, safety and stability aspects. From selected gas generants the following data were measured: Estimation of thermal stability using DSC methods and mass‐loss tests; Pressure/time curves in the ballistic bomb; Rate of product gases by means of gaschromatography.
Thermal Analysis of Ammonium Dinitramide Decomposition
Authors: Löbbecke Stefan , Krause Horst H. , Pfeil Achim 
Published: May 2005

AbstractThe new energetic material ammonium dinitramide (ADN), NH4N(NO2)2, has been investigated with regard to its thermal properties and decomposition behavior. Thermal decomposition of ADN is observed after complete melting at 91.5 °C. The main decomposition pathway is based on the formation of NH4NO3 and N2O followed by the thermal decomposition of NH4NO3 to N2O and H2O at higher temperatures. Side reactions forming NO2, NO, NH3, N2 and O2 are described and a mechanism for the acid‐catalized decomposition of hydrogen dinitramide, dissociation product of ADN, is proposed.
Investigation of Slow‐Propagation Tungsten Delay Mixtures
Authors: Shachar Elie , Gany Alon 
Published: May 2005

AbstractThe burning characteristics and reliability of slow‐propagation tungsten delay mixtures (characteristic time 38–42 s/in) were studied experimentally by using various mixture compositions and tungsten particle sizes. Thermal analysis showed that potassium perchlorate is vital to initiate the reaction. Gravimetric analysis indicated that during the reaction overall mass loss of the delay mixtures did not exceed 5% compared to their initial mass. A mixture containing a tungsten powder of 6–8 μm was found to have the lowest effective activation energy, facilitating good ignition and burning zone propagation. The results of this study were successfully used to design a tiny delay which exhibited reliable ignition, burning and propagation characteristics under extreme conditions.
Plate Velocities for Asymmetric Sandwiches
Authors: Held Manfred 
Published: May 2005

AbstractFor the prediction of the plate velocities of asymmetric sandwiches, a simple equation basing only on the momentum law will be presented, which is easier to use than the formula given in the literature. It predicts nearly the same results or the deviations are smaller than the experimental scatters. Practical calculation examples are presented for the users.
Influence of Specific Surface Area of Aluminium Powder on the reactivity of aluminium/ammonium perchlorate composition
Authors: Rajendran A. G. , Kartha C. B. , Babu V. V. 
Published: May 2005

AbstractAluminium/ammonium perchlorate (40/60 wt.%) is a pyrotechnic composition widely used as an igniter charge for small calibre rocket motors. Five different types of aluminium powders with specific surface area varying from 0.52 m2/g to 6.00 m2/g have been studied to evaluate the influence of specific surface area on the ignition characteristics of the charge. While the peak pressure varies from 35.5 ksc to 54.5 ksc (0.30 g in 48.0 cm3 vol.), the corresponding time to Pmax varies from 11.2 ms to 1.6 ms showing higher reactivity of the mix with increase in aluminium surface area. This order of reactivity agrees with the order of reactivity determined from the DTG curves of the metal oxidation by comparing the peak height to half width ratio. However, the total gas generated by all the charges is approximately the same and the difference in peak pressure is caused by the difference in the rate of reaction and after about 30 ms all the compositions exhibit the same order of temperature and pressure. The charge has got an ignition temperature of about 640 K and the ignition is preceded by the exothermic decomposition of ammonium perchlorate. The activation energy varies from 92.2 kJ/mol to 127.6 kJ/mol and the corresponding pre‐exponential factor from 9.7 × 106 min−1 to 7.1 × 109 min−1 and they exhibit the kinetic compensation effect with an isokinetic temperature of 647 K.
An HPLC Method for Analysis of HNIW and TNAZ in an explosive mixture
Authors: Persson Birgitta , Östmark Henric , Bergman Helena 
Published: May 2005

AbstractThis paper presents a general HPLC method for qualitative and quantitative analysis of mixtures of explosives. The method has successfully been tested on the following explosives: RDX, 2,4,6‐TNT, 2,4‐DNT, HMX, PETN, Tetryl, HNS, TNAZ and HNIW. The method permits a nine component explosive mixture analysis in less than 10 minutes. For HNIW and TNAZ the detection limit was less than 5 ng.
AM1 study of ammonium 3‐nitro‐1,2,4‐triazole‐5‐onate (ANTO)
Authors: Cheng‐Wei Chang , Yeong‐Ming Wong , Te‐Chuan Chang , Cheng Chen 
Published: May 2005

AbstractThe geometrical structure of ANTO investigated by using AM1 semiempirical MO calculation shows that there are four distinguished intermolecular hydrogen bonding in the ANTO molecular/ionic system. The binding energies of NTO−/NH4+, NTO−/H2O and NH4+/H2O are −230.516 kcal/mol −136.671 kcal/mol and −14.664 kcal/mol, respectively. The charge densities show the deprotonation ability of various nitrogen's of NTO− ion, that result corresponds to some other's early study.
Accelerated Aging of Plateau Burn Composite Propellant
Authors: Oyumi Yoshio , Kimura Eishu , Nagayama Kiyokazu 
Published: May 2005

AbstractEffects of accelerated aging at 60 °C on combustion characteristics, thermal decomposition, and mechanical properties of high burn rate composite propellant were studied in this paper. Although less change in burn rate was observed until aging period of two weeks, approximately 7% decrease was obtained at a pressure range from 9 MPa to 14 MPa after 32 weeks aging. The pressure range of the plateau‐mesa burning was shifted to higher pressure region by the aging. Although heat of decomposition measured by DSC decreased only 2% in the value, activation energy of thermal decomposition decreased 11%, from 133.3 kJ/mol to 119.5 kJ/mol. Increased CO2 and decreased HCN were also observed in the gaseous product distribution. Iron catalyzed processes involving AP and binder decomposition products were altered with a time of aging and it might generate the plateau burning pressure range shift. The sample kept 32 weeks, however, did not show any significant changes in mechanical properties.
The Kinetics of Detonation of Nitroguanidine
Authors: Leiper G. A. , Cooper J. 
Published: May 2005

AbstractA slightly divergent flow detonation model has been used to model previously published charge diameter data for nitroguanidine. The kinetic form at low density is shown to be of the hot spot/grain burning type. At higher densities the kinetics become progressively thermal explosion in form. The kinetics are discussed in terms of the pressure dependent rate law used in the model and models of hot spot formation in powder explosives. The particular crystal size and form of nitroguanidine used shows characteristics which suggest it to be of the type described by Price as Group 2 at low density but to show a change to Group 1 type behaviour at higher density. The analysis suggests reasons for this and for the observation that an alternative crystal size and form appears to show only Group 1 characteristics.
Theoretical Study on Pyrolysis and Sensitivity of Energetic Compounds. Part I: Simple model molecules containing NO2 Group
Authors: Heming Xiao , Jianfen Fan , Xuedong Gong 
Published: May 2005

AbstractUHF (Unrestricted Hartree‐Fock) Molecular Orbital calculations have been first performed for studying the pyrolysis mechanism of five compounds (nitromethane, methyl nitrate, nitroamine, methyl nitroamine and dimethyl nitroamine) containing NO2 group as the simple models of organic explosives by using PM3 and AM1 methods. The potential energy curves and activation energies of the five pyrolysis reactions (into radicals) have been obtained. The activation energies are consistent with the experimental impact sensitivity of these three kinds of explosives: C‐nitro < N‐nitro < O‐nitro compounds. It is found that there is a parallel linear relationship between the bond orders of NNO2 bond in the molecules of three nitroamine compounds and the activation energies of their initiation reactions breaking NNO2 bond. The obtained correlation coefficients between bond orders and activation energies from PM3 and AM1 calculations are 0.9962 and 0.9999, respectively.
Two trifluoperazine‐binding sites on calmodulin predicted from comparative molecular modeling with troponin‐C
Authors: Strynadka Natalie C. J. , James Michael N. G. 
Published: May 2005

AbstractAmong the known regulatory proteins that are conformationally sensitive to the binding of calcium ions, calmodulin and troponin‐C have the greatest primary sequence homology. This observation has led to the conclusion that the most accurate predicted molecular model of calmodulin would be based on the X‐ray crystallographic coordinates of the highly refined structure of turkey skeletal troponin‐C. This paper describes the structure of calmodulin built from such a premise. The resulting molecular model was subjected to conjugate gradient energy minimization to remove unacceptable intramolecular non‐bonded contacts. In the analysis of the resulting structure, many features of calmodulin, including the detailed conformation of the Ca2+‐binding loops, the amino‐ and carboxy‐terminal hydrophobic patches of the Ca2+‐bound form, and the several clusters of acidic residues can be reconciled with much of the previously published solution data. Calmodulin in missing the N‐terminal helix characteristic of troponin‐C. The deletion of three residues from the central helical linker (denoted D/E in troponin‐D) shortens the molecule and changes the orientation of the two domains of calmodulin by 60° relative to those in troponin‐C. The molecular model has been used to derive two possible binding sites for the antipsychotic drug trifluoperazine, a potent competitive inhibitor of calmodulin activity.
Hydrophobicity of amino acid subgroups in proteins
Authors: Lesser Glenn J. , Rose George D. 
Published: May 2005

AbstractProtein folding studies often utilize areas and volumes to assess the hydrophobic contribution to conformational free energy (Richards, F. M. Annu. Rev. Biophys. Bioeng. 6:151–176, 1977). We have calculated the mean area buried upon folding for every chemical group in each residue within a set of X‐ray elucidated proteins. These measurements, together with a standard state cavity size for each group, are documented in a table. It is observed that, on average, each type of group buries a constant fraction of its standard state area. The mean area buried by most, though not all, groups can be closely approximated by summing contributions from three characteristic parameters corresponding to three atom types: (1) carbon or sulfur, which turn out to be 86% buried, on average; (2) neutral oxygen or nitrogen, which are 40% buried, on average; and (3) charged oxygen or nitrogen, which are 32% buried, on average.
Comparison of the structures of globins and phycocyanins: Evidence for evolutionary relationship
Authors: Pastore Annalisa , Lesk Arthur M. 
Published: May 2005

AbstractGlobins and phycocyanins are two classes of proteins with different function, different ligands, and no substantial sequence similarity, yet the conformations of their polypeptide chains show very similar folding patterns. Does this arise from a genuine, albeit very distant, evolutionary relationship, or does it represent a common solution of a structural problem? We address this question by a very detailed comparison of the structures of the two protein families. An analysis of the helices and their interactions shows many features common to globins and phycocyanins, including some exceptional features of the globins such as a 3–10 C helix and the unusual “crossed‐ridge” packing pattern at the B/E helix interfaces. We conclude that the evidence supports the hypothesis of distant evolutionary relationship between globins and phycocyanins.
Distinct character in hydrophobicity of amino acid compositions of mitochondrial proteins
Authors: Nakashima Hiroshi , Nishikawa Ken , Ooi Tatsuo 
Published: May 2005

AbstractA compact mitochondrial gene contains all essential information about the synthesis of mitochondrial proteins which play their roles in a small compartment of the mitochondrium. Almost no noncoding regions have been found through the gene, but a necessary set of tRNAs for the 20 amino acids is provided for biosynthesis, some of them coding different amino acids from those in a usual cell. Since the gene is so compact that the produced proteins would have some characteristic aspects for the mitrochondrium, amino acid compositions of mitochondrial proteins (mt‐proteins) were examined in the 20‐dimensional composition space. The results show that compositions of proteins translated from the mitochondrial genes have a distinct character having more hydrophobic content than others, which is illustrated by a clustered distribution in the multidimensional composition space. The cluster is located at the tail edge of the global distribution pattern of a Gaussian shape for other various kinds of proteins in the space. The mt‐proteins are rich in hydrophobic amino acids as is a membrane protein, but are different from other membrane proteins in a lesser content of Val. A good correlation found between the base and amino acid compositions for the mitochondria was examined in comparison to those of organisms such as thermophilic bacterium having an extreme G‐C‐rich base composition.
Stereochemical quality of protein structure coordinates
Authors: Morris Anne Louise , MacArthur Malcolm W. , Hutchinson E. Gail , Thornton Janet M. 
Published: May 2005

AbstractMethods have been developed to assess the stereochemical quality of any protein structure both globally and locally using various criteria. Several parameters can be derived from the coordinates of a given structure. Global parameters include the distribution of ϕ,ψ and χ1 torsion angles, and hydrogen bond energies. There are clear correlations between these parameters and resolution; as the resolution improves, the distribution of the parameters becomes more clustered. These features show a broad distribution about ideal values derived from high‐resolution structures. Some structures have tightly clustered distributions even at relatively low resolutions, while others show abnormal scatter though the data go to high resolution. Additional indicators of local irregularity include proline ϕ angles, peptide bond planarities, disulfide bond lengths, and their χ3 torsion angles. These stereochemical parameters have been used to generate measures of stereochemical quality which provide a simple guide as to the reliability of a structure, in addition to the most important measures, resolution and R‐factor. The parameters used in this evaluation are not novel, and are easily calculated from structure coordinates. A program suite is currently being developed which will quickly check a given structure, highlighting unusual stereochemistry and possible errors.
The molecular structure of UDP‐galactose 4‐epimerase from Escherichia coli determined at 2.5 Å resolution
Authors: Bauer Alan J. , Rayment Ivan , Frey Perry A. , Holden Hazel M. 
Published: May 2005

AbstractUDP‐galactose 4‐epimerase catalyzes the conversion of UDP‐galactose to UDP‐glucose during normal galactose metabolism. The molecular structure of UDP‐galactose 4‐epimerase from Escherichia coli has now been solved to a nominal resolution of 2.5 Å. As isolated from E. coli, the molecule is a dimer of chemically identical subunits with a total molecular weight of 79,000. Crystals of the enzyme used for this investigation were grown as a complex with the substrate analogue, UDP‐benzene, and belonged to the space group P212121 with unit cell dimensions of a = 76.3 Å, b = 83.1 Å, c = 132.1 Å, and one dimer per asymmetric unit. An interpretable electron density map calculated to 2.5 Å resolution was obtained by a combination of multiple isomorphous replacement with six heavy atom derivatives, molecular averaging, and solvent flattening.Each subunit of epimerase is divided into two domains. The larger N‐terminal domain, composed of amino acid residues 1–180, shows a classic NAD+ binding motif with seven strands of parallel β‐pleated sheet flanked on either side of α‐helices. The seventh strand of the β‐pleated sheet is contributed by amino acid residues from the smaller domain. In addition, this smaller C‐terminal domain, consisting of amino acid residues 181–338, contains three strands of β‐pleated sheet, two major α‐helices and one helical turn. The substrate analogue, UDP‐benzene, binds in the cleft located between the two domains with its phenyl ring in close proximity to the nicotinamide ring of NAD+. Contrary to the extensive biochemical literature suggesting that epimerase binds only one NAD+ per functional dimer, the map clearly shows electron density for two nicotinamide cofactors binding in symmetry‐related positions in the dimer. Likewise, each subunit in the dimer also binds one substrate analogue.