The Effect of Particle Strength on the Ballistic Resistance of Shear Thickening Fluids

The response of shear thickening fluids (STFs) under ballistic impact has received considerable attention due to its field-responsive nature. While efforts have primarily focused on the response of traditional ballistic fabrics impregnated with fluids, the response of pure STFs to penetration has received limited attention. In the present study, the ballistic response of pure STFs is investigated and the effect of fluid density and particle strength on ballistic performance is isolated. The loss of ballistic resistance of STFs at higher impact velocities is governed by particle strength, indicating the range of velocities over which they may provide effective armor solutions.Comment: 4 pages, 4 figure

Post-Transplant Outcomes in High-Risk Compared with Non-High-Risk Multiple Myeloma: A CIBMTR Analysis.

Conventional cytogenetics and interphase fluorescence in situ hybridization (FISH) identify high-risk multiple myeloma (HRM) populations characterized by poor outcomes. We analyzed these differences among HRM versus non-HRM populations after upfront autologous hematopoietic cell transplantation (autoHCT). Between 2008 and 2012, 715 patients with multiple myeloma identified by FISH and/or cytogenetic data with upfront autoHCT were identified in the Center for International Blood and Marrow Transplant Research database. HRM was defined as del17p, t(4;14), t(14;16), hypodiploidy (-Y) or chromosome 1 p and 1q abnormalities; all others were non-HRM. Among 125 HRM patients (17.5%), induction with bortezomib and immunomodulatory agents (imids) was higher compared with non-HRM (56% versus 43%, P \u3c .001) with similar pretransplant complete response (CR) rates (14% versus 16%, P .1). At day 100 post-transplant, at least a very good partial response was 59% in HRM and 61% in non-HRM (P = .6). More HRM patients received post-transplant therapy with bortezomib and imids (26% versus 12%, P = .004). Three-year post-transplant progression-free (PFS) and overall survival (OS) rates in HRM versus non-HRM were 37% versus 49% (P \u3c .001) and 72% versus 85% (P \u3c .001), respectively. At 3 years, PFS for HRM patients with and without post-transplant therapy was 46% (95% confidence interval [CI], 33 to 59) versus 14% (95% CI, 4 to 29) and in non-HRM patients with and without post-transplant therapy 55% (95% CI, 49 to 62) versus 39% (95% CI, 32 to 47); rates of OS for HRM patients with and without post-transplant therapy were 81% (95% CI, 70 to 90) versus 48% (95% CI, 30 to 65) compared with 88% (95% CI, 84 to 92) and 79% (95% CI, 73 to 85) in non-HRM patients with and without post-transplant therapy, respectively. Among patients receiving post-transplant therapy, there was no difference in OS between HRM and non-HRM (P = .08). In addition to HRM, higher stage, less than a CR pretransplant, lack of post-transplant therapy, and African American race were associated with worse OS. In conclusion, we show HRM patients achieve similar day 100 post-transplant responses compared with non-HRM patients, but these responses are not sustained. Post-transplant therapy appeared to improve the poor outcomes of HRM

Validation of the Gurney model for heterogeneous systems

Accelerating material to very high speed (up to multiple km/s) is one of the primary uses of high explosives. Thus, the magnitude and mechanisms of energy transfer from a detonating high explosive (HE) to material placed in contact with the charge are critical in engineering applications. When heterogeneous, non-conventional explosives are used to drive material, or when heterogeneous material is driven by explosives, mesoscale multiphase interactions and dissipative mechanisms complicate the analysis and modelling of the explosive-material interaction using both analytic techniques and finite element codes.First, a planar flyer plate charge leveraging Photonic Doppler Velocimetry (PDV) was designed to measure the explosive output of heterogeneous HEs. Homogeneous, amine-sensitized liquid nitromethane was used as a benchmark explosive, and the flyer-mass to charge-mass ratio M/C was varied from 0.03 to 4.65. These experiments validated that the Gurney model is accurate to within 5%, except for very small values of M/C where the error grows to 10%. Importantly, these experiments also validated flyer launch angle predictions and PDV tilt correction techniques up to very large launch angles.Second, the validated flyer plate charge was used to measure the metal driving output of explosives loaded with inert additives. Photonic Doppler Velocimetry was again used to measure flyer acceleration. A wide range of formulations and particle additives were tested: packed particle beds saturated with nitromethane, gelled nitromethane with suspended particles, and C-4 admixed with particles. A slapper initiated charge was also used in order to determine the effect of detonation wave incidence angle on flyer acceleration. The Gurney curves for several formulations were also measured. Results were analysed in the context of a modified form of the Gurney equation which included the entrainment of the inert particles in the detonation products with no slip. Agreement was found to be acceptable for an engineering model for all but the very heavily loaded explosives.Third, a modified, symmetric version of the experimental geometry was used to evaluate the effect of aluminium addition on the propulsive capability of gelled nitromethane. Unlike typical studies of aluminized explosives using the cylinder test, in the present experiments flyer plates of widely varying thickness were used to ascertain if casing expansion timescale influences energy deposition by the aluminium. Time-resolved flyer surface velocity measurements were performed with PDV. Regardless of flyer thickness and aluminium particle size, aluminized explosives drove the flyer plates faster than an equivalent neat explosive within 4--6 us. This implied prompt reaction and energy delivery by the aluminium to the detonation products.Finally, the explosive dispersal of a wide variety of granular materials in spherical geometry was performed and various phenomenology related to consolidated shell fracture and particle jet formation were discussed – particularly the segregation and jetting of binary mixtures. The terminal velocity of the jet tips for all experiments were compared to the spherical Gurney model. Experimental terminal velocities were 40\textendash{70}\% lower than what was predicted by the Gurney model, demonstrating that compaction significantly dissipates explosive energy. A modified Gurney model accounting for dissipation as a function of \textit{M/C} and porosity was compared and shown to accurately predict the dispersant velocity over the full range of \textit{M/C} and materials considered with a maximum error of 17\%.L'accélération du matériel à très grande vitesse (jusqu'à plusieurs km/s) est l'une des principales utilisations des explosifs à haute teneur. Ainsi, l'ampleur et les mécanismes du transfert d'énergie de la détonation des explosifs élevés (HE) à des matériaux mis en contact avec la charge sont essentiels dans les applications d'ingénierie. Lorsqu'un explosif hétérogène et non conventionnel est utilisé pour conduire du matériel, ou lorsqu’un matériel hétérogène est entraîné par des explosifs, les interactions multiphasiques à mésoéchelle et les mécanismes dissipatifs sont difficilement modélisés par des codes d'éléments finis et des outils analytiques.Les explosifs qui ont été fortement dilués avec du matériel inerte intéressent les applications de conduite en métal où l'élimination d'un choc transmis dans le métal est souhaitable: la spallation et l'éjection du matériau peuvent être supprimées et le chauffage et le cisaillement peuvent être réduits. Alternativement, l'ajout de métaux réactifs peut augmenter la performance d'un explosif lors de la conduite de métal, à condition que les particules réagissent suffisamment rapidement. Les explosifs fortement dilués avec des particules denses sont également intéressants pour des charges d'impulsions limitées à longue distance et de haute intensité à courte distance. La capacité de ces explosifs à accélérer l'enveloppe auxiliaire d’une charge est donc importante à quantifier. Lorsque des explosifs sont utilisés pour conduire des matériaux granulaires, le compactage par choc dissipe l'énergie explosive, ce qui entraîne une vitesse de dispersion inférieure à ce que l'on prévoit pour les enveloppes homogènes. La quantification de la vitesse des dispersants est essentielle pour le transfert de moment cinétique d’explosions enterrées, l'atténuation des impulsions/explosions par des matériaux granulaires, et la performance de certaines charges améliorées. Les effets hétérogènes présentent donc un intérêt pour plusieurs applications d'ingénierie explosive spécialisées. Dans la thèse actuelle, les effets des hétérogénéités sur l'accélération du matériau par des explosifs ont été examinés en détail par l'expérimentation. Tout au long, les résultats de la thèse ont été analysés dans le contexte du modèle Gurney, l'un des outils analytiques les plus omniprésents pour estimer la vitesse à laquelle les matériaux sont entraînés par des explosifs ou pour comparer la production thermo-chimique des explosifs. Diverses modifications du modèle Gurney ont été proposées et / ou évaluées.En conclusion, la précision et l’utilité du modèle Gurney a été démontrée pour une variété de systèmes hétérogènes. Étant donné que le modèle de Gurney est effectivement une loi d'échelle de transfert d'énergie, il peut être facilement adapté en modifiant les équations de conservation pour tenir compte des ajouts au système ou simplement en ajoutant des termes d'échelle au ratio \textit{M/C} et à l'énergie explosive efficace, E

Phase velocity techniques for the implosion of pressurized linear drivers

The present study deals with the evaluation of several explosive phase velocity techniques to produce very high apparent detonation velocities on linear or cylindrical targets. In particular, the pairing of two explosive components with different detonation velocities to drag a structured detonation wave was shown to be accurate in generating desired phase velocities. The technique of subdividing a detonation wave into multiple, discrete detonation channels and injecting them into the desired geometry was also evaluated and shown to be similarly accurate. Analytical models for designing the explosive components in these techniques in order to produce a desired phase velocity are presented in detail. A novel method of generating an axisymmetrical, implosive linear phase velocity was also developed by varying the wall thickness of a cylindrical metal flyer/liner. This device was experimentally demonstrated to produce phase velocities but with significant deviations from analytical modelling predictions. The two component phasing technique was also applied to a linear explosive shock tube. The shock tube was constructed from a thin-walled metal tube and surrounded by a thin annulus of explosives and then a thick-walled metal tube. The phased detonation wave was injected via a thin slit in the top of the thick-walled tube. A quasi-steady shock wave was driven at velocities between 10.5~km/s and 11~km/s with this device.L'étude présente porte sur l'évaluation de plusieurs techniques pour générer une vitesse de phase dans un explosif afin de produire de très hautes vitesses de détonation sur des cibles linéaires ou cylindriques. En particulier, il a été démontré que le jumelage de deux composantes explosives ayant des vitesses de détonation différentes pour faire glisser une onde de détonation structurée est une méthode pouvant précisément générer des vitesses de phase désirées. La méthode de la division d'une onde de détonation dans plusieurs canaux individuels fut évaluée et il fut démontré qu'elle est aussi précise. Des modèles analytiques pour la conception des composantes explosives nécessaires à la production des vitesses de phase désirées en utilisant ces techniques sont présentés en détail. Une nouvelle méthode pour générer une vitesse de phase axisymétrique, implosive et linéaire a été également mise au point en faisant varier l'épaisseur de la paroi d'un tube métallique cylindrique. Il fut démontré que cet appareil est capable de produire des vitesses de phase, mais avec des écarts importants avec les prévisions analytiques. La technique qui utilise les deux composantes a également été appliquée à un tube à chocs explosif linéaire. Le tube à chocs a été construit à partir d'un tube métallique à parois mince et entouré par un anneau mince d'explosifs puis un tube de métal à parois épaisse. L'onde de détonation a été progressivement injectée par une mince fente dans le haut du tube à parois épaisse. Une onde de choc a été entraînée à des vitesses allant jusqu'à 11~km/s avec cet appareil

Solvothermal Synthesis of Tetravalent Uranium with Isophthalate or Pyromellitate Ligands

International audienc

Explosive fragmentation of liquids in spherical geometry

Rapid acceleration of a spherical shell of liquid following detonation of a high explosive causes the liquid to form fine jets that are similar in appearance to the particle jets that are formed during explosive dispersal of a packed layer of solid particles. Of particular interest is determining the dependence of the scale of the jet-like structures on the physical parameters of the system, including the fluid properties (e.g., density, viscosity, surface tension) and the ratio of the mass of the liquid to that of the explosive. The present paper presents computational results from a multi-material hydrocode describing the dynamics of the explosive dispersal process. The computations are used to track the overall features of the dispersal of the liquid layer, including the wave dynamics, and motion of the spall and accretion layers. The results are compared with experimental results of spherical charges surrounded by a variety of different fluids, including water, glycerol, ethanol, and vegetable oil, which together encompass a significant range of fluid properties. The results show that the number of jet structures is not sensitive to the fluid properties, but primarily dependent on the mass ratio. Above a certain mass ratio of liquid fill to explosive burster (F/B), the number of jets is approximately constant and consistent with an empirical model based on the maximum thickness of the accretion layer. For small values of F/B, the number of liquid jets is reduced, in contrast with explosive powder dispersal, where small F/B yields a larger number of particle jets. A hypothetical explanation of these features based on nucleation of cavitation is explored numerically

PCR-based diagnostic methods for 'Candidatus Liberibacter solanacearum'

'Candidatus Liberibacter solanacearum' is an economically important pathogen in the Americas, New Zealand and Europe. The primary objective of this review is to systematically investigate the polymerase chain reaction (PCR)-based methods used for its detection in plant samples. Several databases were searched from the inception of the relevant literature up to August 2018. This review identified 53 studies that met all the inclusion criteria. The performance of the different methods was also compared, however due to data heterogeneity and insufficient evidence on the sensitivity of all assays used, a meta-analysis of the data was not possible. Nonetheless, the review indicates that the rtPCR designed to the 16S ribosomal RNA gene can be routinely employed as a fast, cost-effective, and reliable detection technique in diagnostic laboratories