research-and-development-of-high-performance-explosives

Research and Development of High-performance Explosives

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance ...

US Army ARDEC, Picatinny Arsenal

This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron microscopy (SEM), and UV-vis spectroscopy. Preliminary data indicate that CPs synthesized by this method exhibit novel morphology and high conductivity comparable to that synthesized by traditional methods.

Electrochemical synthesis and characterization of conducting polymers in supercritical carbon dioxide.

We study the evolution of the network properties of a populated network embedded in a genotype space characterized by either a low or a high number of potential links, with particular emphasis on the connectivity and clustering. Evolution produces two distinct types of network. When a specific genotype is only able to influence a few other genotypes, the ecosystem consists of separate non-interacting clusters (i.e. isolated compartments) in genotype space. When different types may influence a large number of other sites, the network becomes one large interconnected cluster. The distribution of interaction strengths--but not the number of connections--changes significantly with time. We find that the species abundance is only realistic for a high level of species connectivity. This suggests that real ecosystems form one interconnected whole in which selection leads to stronger interactions between the different types. Analogies with niche and neutral theory and assembly models are also considered.

Network properties, species abundance and evolution in a model of evolutionary ecology.

Temperature compensation contributes to the accuracy of biological timing by preventing circadian rhythms from running more quickly at high than at low temperatures. We previously identified quantitative trait loci (QTL) with temperature-specific effects on the circadian rhythm of leaf movement, including a QTL linked to the transcription factor FLOWERING LOCUS C (FLC). We have now analyzed FLC alleles in near-isogenic lines and induced mutants to eliminate other candidate genes. We showed that FLC lengthened the circadian period specifically at 27 degrees C, contributing to temperature compensation of the circadian clock. Known upstream regulators of FLC expression in flowering time pathways similarly controlled its circadian effect. We sought to identify downstream targets of FLC regulation in the molecular mechanism of the circadian clock using genome-wide analysis to identify FLC-responsive genes and 3503 transcripts controlled by the circadian clock. A Bayesian clustering method based on Fourier coefficients allowed us to discriminate putative regulatory genes. Among rhythmic FLC-responsive genes, transcripts of the transcription factor LUX ARRHYTHMO (LUX) correlated in peak abundance with the circadian period in flc mutants. Mathematical modeling indicated that the modest change in peak LUX RNA abundance was sufficient to cause the period change due to FLC, providing a molecular target for the crosstalk between flowering time pathways and circadian regulation.

FLOWERING LOCUS C mediates natural variation in the high-temperature response of the Arabidopsis circadian clock.

Common contemporary practice within the nuclear magnetic resonance (NMR) metabolomics community is to evaluate and validate novel algorithms on empirical data or simplified simulated data. Empirical data captures the complex characteristics of experimental data, but the optimal or most correct analysis is unknown a priori; therefore, researchers are forced to rely on indirect performance metrics, which are of limited value. In order to achieve fair and complete analysis of competing techniques more exacting metrics are required. Thus, metabolomics researchers often evaluate their algorithms on simplified simulated data with a known answer. Unfortunately, the conclusions obtained on simulated data are only of value if the data sets are complex enough for results to generalize to true experimental data. Ideally, synthetic data should be indistinguishable from empirical data, yet retain a known best analysis.

Characterization of 1H NMR spectroscopic data and the generation of synthetic validation sets.

Molecular studies of bacterial virulence are enhanced by expression of recombinant DNA during infection to allow complementation of mutants and expression of reporter proteins in vivo. For highly pathogenic bacteria, such as Yersinia pestis, these studies are currently limited because deliberate introduction of antibiotic resistance is restricted to those few which are not human treatment options. In this work, we report the development of alternatives to antibiotics as tools for host-pathogen research during Yersinia pestis infections focusing on the diaminopimelic acid (DAP) pathway, a requirement for cell wall synthesis in eubacteria. We generated a mutation in the dapA-nlpB(dapX) operon of Yersinia pestis KIM D27 and CO92 which eliminated the expression of both genes. The resulting strains were auxotrophic for diaminopimelic acid and this phenotype was complemented in trans by expressing dapA in single and multi-copy. In vivo, we found that plasmids derived from the p15a replicon were cured without selection, while selection for DAP enhanced stability without detectable loss of any of the three resident virulence plasmids. The dapAX mutation rendered Y. pestis avirulent in mouse models of bubonic and septicemic plague which could be complemented when dapAX was inserted in single or multi-copy, restoring development of disease that was indistinguishable from the wild type parent strain. We further identified a high level, constitutive promoter in Y. pestis that could be used to drive expression of fluorescent reporters in dapAX strains that had minimal impact to virulence in mouse models while enabling sensitive detection of bacteria during infection. Thus, diaminopimelic acid selection for single or multi-copy genetic systems in Yersinia pestis offers an improved alternative to antibiotics for in vivo studies that causes minimal disruption to virulence.

Novel genetic tools for diaminopimelic acid selection in virulence studies of Yersinia pestis.

Organophosphates are a group of pesticides and chemical warfare nerve agents that inhibit acetylcholinesterase, the enzyme responsible for hydrolysis of the excitatory neurotransmitter acetylcholine. Numerous structural variants exist for this chemical class, and data regarding their toxicity can be difficult to obtain in a timely fashion. At the same time, their use as pesticides and military weapons is widespread, which presents a major concern and challenge in evaluating human toxicity. To address this concern, a quantitative structure-activity relationship (QSAR) was developed to predict pentavalent organophosphate oxon human acetylcholinesterase bimolecular rate constants. A database of 278 three-dimensional structures and their bimolecular rates was developed from 15 peer-reviewed publications. A database of simplified molecular input line entry notations and their respective acetylcholinesterase bimolecular rate constants are listed in Supplementary Material, Table I. The database was quite diverse, spanning 7 log units of activity. In order to describe their structure, 675 molecular descriptors were calculated using AMPAC 8.0 and CODESSA 2.7.10. Orthogonal projection to latent structures regression, bootstrap leave-random-many-out cross-validation and y-randomization were used to develop an externally validated consensus QSAR model. The domain of applicability was assessed by the William's plot. Six external compounds were outside the warning leverage indicating potential model extrapolation. A number of compounds had residuals >2 or <-2, indicating potential outliers or activity cliffs. The results show that the HOMO-LUMO energy gap contributed most significantly to the binding affinity. A mean training R (2) of 0.80, a mean test set R (2) of 0.76 and a consensus external test set R (2) of 0.66 were achieved using the QSAR. The training and external test set RMSE values were found to be 0.76 and 0.88. The results suggest that this QSAR model can be used in physiologically based pharmacokinetic/pharmacodynamic models of organophosphate toxicity to determine the rate of acetylcholinesterase inhibition.

Quantitative structure-activity relationships for organophosphates binding to acetylcholinesterase.

Inhalation exposure models are becoming the preferred method for the comparative study of respiratory infectious diseases due to their resemblance to the natural route of infection. To enable precise delivery of pathogen to the lower respiratory tract in a manner that imposes minimal biosafety risk, nose-only exposure systems have been developed. Early inhalation exposure technology for infectious disease research grew out of technology used in asthma research where predominantly the Collison nebulizer is used to generate an aerosol by beating a liquid sample against glass. Although infectious aerosol droplets of 1-5 Î¼m in size can be generated, the Collison often causes loss of viability. In this work, we evaluate a gentler method for aerosolization of living cells and describe the use of the Sparging Liquid Aerosol Generator (SLAG) in a rat pneumonic plague model. The SLAG creates aerosols by continuous dripping of liquid sample on a porous metal disc. We show the generation of 0.5-1 Î¼m Yersinia pestis aerosol particles using the SLAG with spray factors typically ranging from 10(-7) to 10(-8) with no detectable loss of bacterial viability. Delivery of these infectious particles via nose-only exposure led to the rapid development of lethal pneumonic plague. Further, we evaluated the effect of restraint-stress imposed by the nose-only exposure chamber on early inflammatory responses and bacterial deposition. Elevated serum corticosterone which peaked at 2 h post-procedure indicated the animals experienced stress as a result of restraint in the nose-only chamber. However, we observed no correlation between elevated corticosterone and the amount of bacterial deposition or inflammation in the lungs. Together these data demonstrate the utility of the SLAG and the nose-only chamber for aerosol challenge of rodents by Y. pestis.

Host stress and immune responses during aerosol challenge of Brown Norway rats with Yersinia pestis.

Mod&egrave;les d&#39;exposition par inhalation sont de plus la m&eacute;thode privil&eacute;gi&eacute;e pour l&#39;&eacute;tude comparative des maladies respiratoires infectieuses en raison de leur ressemblance avec la voie naturelle de l&#39;infection. Pour activer la livraison pr&eacute;cise de l&#39;agent pathog&egrave;ne pour les voies respiratoires inf&eacute;rieures d&#39;une mani&egrave;re qui impose le risque minime de bios&eacute;curit&eacute;, ont &eacute;labor&eacute; des syst&egrave;mes d&#39;exposition nez seulement. D&eacute;but technologie d&#39;exposition par inhalation pour la recherche sur les maladies infectieuses issu de la technologie utilis&eacute;e dans la recherche sur l&#39;asthme o&ugrave; principalement le n&eacute;buliseur Collison sert &agrave; g&eacute;n&eacute;rer un a&eacute;rosol en battant un &eacute;chantillon liquide contre le verre. Bien que les gouttelettes infectieuses a&eacute;rosol de 1 &agrave; 5 &mu;m de taille peuvent &ecirc;tre g&eacute;n&eacute;r&eacute;es, la Collison provoque souvent perte de viabilit&eacute;. Dans ce travail, nous &eacute;valuer une m&eacute;thode plus douce pour l&#39;a&eacute;rosolisation des cellules vivantes et d&eacute;crivent l&#39;utilisation de la g&eacute;n&eacute;ratrice barbotage d&#39;a&eacute;rosol liquide (scories) dans un mod&egrave;le de peste pulmonaire chez le rat. Le laitier cr&eacute;e des a&eacute;rosols en continu d&eacute;goulinant de liquide &eacute;chantillon sur un disque de m&eacute;tal poreux. Nous montrons &agrave; la g&eacute;n&eacute;ration de 0,5 &agrave; 1 &mu;m Yersinia pestis a&eacute;rosols particules &agrave; l&#39;aide de la scorie avec facteurs de pulv&eacute;risation en g&eacute;n&eacute;ral allant de 10(-7) &agrave; 10(-8) sans perte d&eacute;celable de la viabilit&eacute; bact&eacute;rienne. Livraison de ces particules infectieuses par l&#39;exposition nez seulement conduit &agrave; l&#39;&eacute;volution rapide de la peste pulmonaire mortelle. De plus, nous avons &eacute;valu&eacute; l&#39;effet de retenue-stress impos&eacute; par la chambre d&#39;exposition nez seulement sur les premi&egrave;res r&eacute;ponses inflammatoires et des d&eacute;p&ocirc;ts bact&eacute;riens. Corticost&eacute;rone s&eacute;rique qui a atteint un sommet apr&egrave;s l&#39;intervention 2 h indique le stress exp&eacute;riment&eacute;s animaux &agrave; la suite de retenue dans la chambre de nez seulement. Cependant, nous avons n&#39;observ&eacute; aucune corr&eacute;lation entre la corticost&eacute;rone &eacute;lev&eacute;e et le montant des d&eacute;p&ocirc;ts bact&eacute;riens ou inflammation dans les poumons. Ensemble, ces donn&eacute;es d&eacute;montrent l&#39;utilit&eacute; de la scorie et de la chambre de nez seulement pour d&eacute;fi d&#39;a&eacute;rosol de rongeurs par Y. pestis.

Stress de l&#39;h&ocirc;te et les r&eacute;ponses immunitaires au cours du d&eacute;fi des a&eacute;rosols de surmulots Brown avec Yersinia pestis.

Modelli di esposizione inalazione stanno diventando il metodo preferito per lo studio comparato delle malattie infettive respiratorie a causa della loro somiglianza con la via naturale d&#39;infezione. Per attivare la consegna precisa dell&#39;agente patogeno al tratto respiratorio inferiore in un modo che impone la biosicurezza minimo rischio, sono stati sviluppati sistemi di esposizione solo naso. Primi tecnologia di esposizione di inalazione per la ricerca di malattie infettive &egrave; cresciuto fuori tecnologia utilizzata nella ricerca di asma dove il nebulizzatore Collison &egrave; usato principalmente per generare un aerosol battendo un campione liquido contro il vetro. Anche se le goccioline di aerosol infettivi di 1-5 &mu;m di dimensione possono essere generate, il Collison provoca spesso perdita di vitalit&agrave;. In questo lavoro, abbiamo valutare un metodo pi&ugrave; dolce per aerosolization di cellule viventi e descrivono l&#39;uso del gorgogliamento Aerosol generatore (SCORIA liquida) in un modello di ratto peste polmonare. La SCORIA crea aerosol dal continuo stillicidio di campione liquido su un disco di metallo poroso. Vi mostriamo la generazione di 0,5-1 &mu;m Yersinia pestis aerosol particelle usando le scorie con fattori spray in genere che vanno da 10(-7) a 10(-8) senza perdita rilevabile di redditivit&agrave; batterica. Consegna di queste particelle infettive tramite esposizione solo naso port&ograve; al rapido sviluppo della peste polmonare letale. Inoltre, abbiamo valutato l&#39;effetto di moderazione-stress imposto dalla camera solo naso esposizione sulle prime risposte infiammatorie e deposizione batterica. Corticosterone sierici elevati che raggiunse dopo 2 h indicato lo stress sperimentato gli animali a seguito di moderazione nella camera solo naso. Tuttavia, abbiamo non osservato alcuna correlazione tra elevati corticosterone e la quantit&agrave; di deposizione batterica o infiammazione dei polmoni. Insieme questi dati dimostrano l&#39;utilit&agrave; delle scorie e la camera solo naso per la sfida di aerosol di roditori di Y. pestis.

Host stress e risposte immunitarie durante la sfida di aerosol di topi Brown Norway con Yersinia pestis.

Development of new vaccines, diagnostics, and therapeutics for biodefense or other relatively rare infectious diseases is hindered by the lack of naturally occurring human disease on which to conduct clinical trials of efficacy. To overcome this experimental gap, the U.S. Food and Drug Administration established the Animal Rule, in which efficacy testing in two well-characterized animal models that closely resemble human disease may be accepted in lieu of large-scale clinical trials for diseases with limited natural human incidence. In this report, we evaluated the Brown Norway rat as a model for pneumonic plague and describe the natural history of clinical disease following inhalation exposure to Yersinia pestis. In high-capacity, high-containment housing, we monitored temperature, activity, heart rate, and rhythm by capturing electronic impulses transmitted from abdominal telemeter implants. Using this system, we show that reduced activity and development of fever are sensitive indications of disease progression. Furthermore, we identified heart arrhythmias as contributing factors to the rapid progression to lethality following the fever response. Together, these data validate the Brown Norway rat as an experimental model for human pneumonic plague and provide new insight that may ultimately lead to novel approaches in postexposure treatment of this devastating infection.

Remote monitoring of the progression of primary pneumonic plague in Brown Norway rats in high-capacity, high-containment housing.

ETS factors have been shown to be dysregulated in breast cancer. ETS factors control the expression of genes involved in many biological processes, such as cellular proliferation, differentiation, and apoptosis. FLI1 is an ETS protein aberrantly expressed in retrovirus-induced hematological tumors, but limited attention has been directed towards elucidating the role of FLI1 in epithelial-derived cancers. Using data mining, we show that loss of FLI1 expression is associated with shorter survival and more aggressive phenotypes of breast cancer. Gain and loss of function cellular studies indicate the inhibitory effect of FLI1 expression on cellular growth, migration, and invasion. Using Fli1 mutant mice and both a transgenic murine breast cancer model and an orthotopic injection of syngeneic tumor cells indicates that reduced Fli1 contributes to accelerated tumor growth. Global expression analysis and RNA-Seq data from an invasive human breast cancer cell line with over expression of either FLI1 and another ETS gene, PDEF, shows changes in several cellular pathways associated with cancer, such as the cytokine-cytokine receptor interaction and PI3K-Akt signaling pathways. This study demonstrates a novel role for FLI1 in epithelial cells. In addition, these results reveal that FLI1 down-regulation in breast cancer may promote tumor progression.

FLI1 expression is correlated with breast cancer cellular growth, migration, and invasion and altered gene expression.

Maternal mRNA transcripts deposited in growing oocytes regulate early development and are under intensive investigation as determinants of egg quality. The research has evolved from single gene studies to microarray and now RNA-Seq analyses in which mRNA expression by virtually every gene can be assessed and related to gamete quality. Such studies have mainly focused on genes changing two- to several-fold in expression between biological states, and have identified scores of candidate genes and a few gene networks whose functioning is related to successful development. However, ever-increasing yields of information from high throughput methods for detecting transcript abundance have far outpaced progress in methods for analyzing the massive quantities of gene expression data, and especially for meaningful relation of whole transcriptome profiles to gamete quality. We have developed a new approach to this problem employing artificial neural networks and supervised machine learning with other novel bioinformatics procedures to discover a previously unknown level of ovarian transcriptome function at which minute changes in expression of a few hundred genes is highly predictive of egg quality. In this paper, we briefly review the progress in transcriptomics of fish egg quality and discuss some future directions for this field of study.

Transcriptomics of mRNA and egg quality in farmed fish: Some recent developments and future directions.

Acclimation to low O2 in many organisms involves changes at the level of the transcriptome. Here we used high-throughput RNA sequencing (RNA-Seq) to explore the global transcriptomic response and specific involvement of a suite of hemocyanin (Hc) subunits to low O2 alone and in combination with high CO2, which naturally co-occurs with low O2. Hepatopancreas mRNA of juvenile L. vannamei exposed to air-saturated water, low O2, or low O2/high CO2 for 4 or 24 h was pooled, sequenced (HiSeq 2500) and assembled (Trinity: 52,190 contigs) to create a deep strand-specific reference transcriptome. Annotation of the assembly revealed sequences encoding the previously described small Hc subunit (HcS), and three full-length isoforms of the large subunit (HcL1-3). In addition to this, a previously unidentified full-length Hc subunit was discovered. Phylogenetic analysis demonstrated the subunit to be a β-type Hc subunit (denoted HcB), making this the first report of a β-type hemocyanin subunit in the Penaeoidea. RNAs of individual shrimp were sequenced; regulated genes identified from pairwise comparisons demonstrated a distinct pattern of regulation between prolonged low O2 and low O2/high CO2 treatments by GO term enrichment analysis (Roff-Bentzen, P < 0.0001), showcasing the stabilization of energetically costly translational machinery, mobilization of energy stores, and downregulation of the ubiquitin/proteasomal degradation machinery. Exposure to hypoxia for 24 h resulted in an increase in all of the full-length hemocyanin subunits (HcS, HcL1, HcL2, HcL3, and HcB). The addition of CO2 to hypoxia muted the transcriptomic response of all the Hc subunits to low O2, except for the β-type subunit.

High CO2 alters the hypoxia response of the Pacific whiteleg shrimp (Litopenaeus vannamei) transcriptome including known and novel hemocyanin isoforms.

Paul E. Anderson

Explosives Research Branch

US Army ARDEC, Picatinny Arsenal

Research and Development of High-performance Explosives

Paul E. Anderson

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US Army ARDEC, Picatinny Arsenal

Research and Development of High-performance Explosives

Explosives Research Branch