Development of on-chip initiation and measurement method for flame velocity self-propagating of thermites [abstract]

Abstract only availableFaculty Mentor: Dr. Shubhra Gangopadhyay, Electrical &Computer EngineeringElectrically triggered detonation of patterned energetic materials were performed to determine the propagation velocity of nano-scale thermite composites comprising of Copper oxide (CuO) and Bismuth oxide (Bi2O3) with Aluminum (Al). The burn rates were measured by monitoring the change of resistance of a thin Platinum film, deposited on a glass substrate by sputter coating, due to detonation of the thermite. A high time resolution was attained by using a NI Labview based sampling at 1 MHz frequency. We have measured burn rates as high as 800m/sec for CuO-Al nanoparticle dispersions using this method. For Bi2O3-Al nanoparticle dispersion the highest burn rate is measured to be 155m/s. The method provides a repeatable way of flame velocity measurement in a laboratory scale for characterization of nanoenergetic materials at a much lower cost than other systems prior to this. Most have used very expensive high-speed cameras for the same task. The detonation initiation aspect of the system deals with the fabrication of a chip with a low-resistance thin-film heater, suitable for initiation of the self-propagating thermite reaction. This system achieved on-chip ignition of nano-scale thermites with a supply voltage as low as 3V. The approach is novel because thermites typically require high-power supply to initiate self-propagating reactions. Thermite materials can be used in primers for detonating high-explosives, micro-thruster devices, smart ammunitions, smart bombs, power generations, etc. and in all these applications, initiation of a thermite reaction is one of the major key components. The on-chip thin film heater, like the speed measurement component will serve the purpose and is a low-cost alternative and can be easily produced on a large scale

Citron binds to PSD-95 at glutamatergic synapses on inhibitory neurons in the hippocampus

Synaptic NMDA-type glutamate receptors are anchored to the second of three PDZ (PSD-95/Discs large/ZO-1) domains in the postsynaptic density (PSD) protein PSD-95. Here, we report that citron, a protein target for the activated form of the small GTP-binding protein Rho, preferentially binds the third PDZ domain of PSD-95. In GABAergic neurons from the hippocampus, citron forms a complex with PSD-95 and is concentrated at the postsynaptic side of glutamatergic synapses. Citron is expressed only at low levels in glutamatergic neurons in the hippocampus and is not detectable at synapses onto these neurons. In contrast to citron, p135 SynGAP, an abundant synaptic Ras GTPase-activating protein that can bind to all three PDZ domains of PSD-95, and Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) are concentrated postsynaptically at glutamatergic synapses on glutamatergic neurons. CaM kinase II is not expressed and p135 SynGAP is expressed in less than half of hippocampal GABAergic neurons. Segregation of citron into inhibitory neurons does not occur in other brain regions. For example, citron is expressed at high levels in most thalamic neurons, which are primarily glutamatergic and contain CaM kinase II. In several other brain regions, citron is present in a subset of neurons that can be either GABAergic or glutamatergic and can sometimes express CaM kinase II. Thus, in the hippocampus, signal transduction complexes associated with postsynaptic NMDA receptors are different in glutamatergic and GABAergic neurons and are specialized in a way that is specific to the hippocampus

Oviposition responses of Aedes mosquitoes to bacterial isolates from attractive bamboo infusions

BACKGROUND: The mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya. Both mosquito species are expanding their geographic distributions and now occur worldwide in temperate and tropical climates. Collection of eggs in oviposition traps (ovitraps) is commonly used for monitoring and surveillance of container-inhabiting Aedes populations by public health agencies charged with managing mosquito-transmitted illness. Addition of an organic infusion in these traps increases the number of eggs deposited. Gravid females are guided to ovitraps by volatile chemicals produced from the breakdown of organic matter by microbes. METHODS: We previously isolated and cultured 14 species of bacteria from attractive experimental infusions, made from the senescent leaves of canebrake bamboo (Arundinaria gigantea). Cultures were grown for 24 h at 28 °C with constant shaking (120 rpm) and cell densities were determined with a hemocytometer. Behavioral responses to single bacterial isolates and to a mix of isolates at different cell densities were evaluated using two-choice sticky-screen bioassay methods with gravid Ae. aegypti and Ae. albopictus. RESULTS: In behavioral assays of a mix of 14 bacterial isolates, significantly greater attraction responses were exhibited by Ae. aegypti and Ae. albopictus to bacterial densities of 10(7) and 10(8) cells/mL than to the control medium. When we tested single bacterial isolates, seven isolates (B1, B2, B3, B5, B12, B13 and B14) were significantly attractive to Ae. aegypti, and six isolates (B1, B5, B7, B10, B13 and B14) significantly attracted Ae. albopictus. Among all the isolates tested at three different cell densities, bacterial isolates B1, B5, B13 and B14 were highly attractive to both Aedes species. CONCLUSIONS: Our results show that at specific cell densities, some bacteria significantly influence the attraction of gravid Ae. aegypti and Ae. albopictus females to potential oviposition sites. Attractive bacterial isolates, when formulated for sustained release of attractants, could be coupled with an ovitrap containing a toxicant to achieve area-wide management of Aedes mosquitoes

Integrating Al with NiO nano honeycomb to realize an energetic material on silicon substrate

Nano energetic materials offer improved performance in energy release, ignition, and mechanical properties compared to their bulk or micro counterparts. In this study, the authors propose an approach to synthesize an Al/NiO based nano energetic material which is fully compatible with a microsystem. A two-dimensional NiO nano honeycomb is first realized by thermal oxidation of a Ni thin film deposited onto a silicon substrate by thermal evaporation. Then the NiO nano honeycomb is integrated with an Al that is deposited by thermal evaporation to realize an Al/NiO based nano energetic material. This approach has several advantages over previous investigations, such as lower ignition temperature, enhanced interfacial contact area, reduced impurities and Al oxidation, tailored dimensions, and easier integration into a microsystem to realize functional devices. The synthesized Al/NiO based nano energetic material is characterized by scanning electron microscopy, X-ray diffraction, differential thermal analysis, and differential scanning calorimetry

Shock Wave Based Cell Transfection and Fluorescent Organosilicate Nanoparticles for Targeted Drug Delivery [abstract]

Nanoscience Poster SessionNanotechnology is a multidisciplinary field that has applications in life sciences, alternative energy, national defense, and electronics. In the field of medicine, nanotechnology may enable intelligent drug delivery using multifunctional nanoparticles. Here, we show two technologies that are envisioned to work in tandem to enable targeted detection and treatment. First, a shock wave generator used for cell transfection and drug/particle delivery is presented. Then, fluorescent dye/drug encapsulated organosilicate nanoparticles (OSNP) with functionalized surfaces for targeted delivery are described. The shock wave generator has been successfully used to deliver various molecules and nanoparticle to inside of the cells with very high efficiency and low cell damage. These include dextran (77 kDa), naked plasmid, and dye-doped organosilicate nanoparticles into several types of cells lines including T47-D, HL-60, and MCF-7, and also into tissues including entire chicken heart (at developmental stage 20-30) and chicken spinal cord. Dye doped organosilicate nanoparticle surfaces conjugated to antibodies have been successfully used in immunofluorescence assays. Close examination of the nanostructure of these particles reveal its unique nanoporous structure. These nanoparticles are currently under investigation for drug encapsulation and sustained release. The implication of these technologies is that the OSNP can be used as targeted drug carriers, and the shock wave generator can be used to deliver the OSNP into cells to which the particles attach. The research on shock wave micro-transfector system has been funded by the National Science Foundation Grant Opportunities for Academic Liason with Industries program

Crystallization of amorphous silicon by self-propagation of nanoengineered thermites

doi:10.1063/1.2450672Crystallization of amorphous silicon (a-Si) thin film occurred by the self-propagation of copper oxide/aluminum thermite nanocomposites. Amorphous Si films were prepared on glass at a temperature of 250 °C by plasma enhanced chemical vapor deposition. The platinum heater was patterned on the edge of the substrate and the CuO/Al nanoengineered thermite was spin coated on the substrate that connects the heater and the a-Si film. A voltage source was used to ignite the thermites followed by a piranha solution (4:1 of H2SO4:H2O2) etch for the removal of residual products of thermite reaction. Raman spectroscopy was used to confirm the crystallization of a-Si.The authors acknowledge Dr. Hameed A. Naseem, Professor of the University of Arkansas, for providing the a-Si samples. The authors also acknowledge the NSF NIRT (Grant No. 1316-1898-01) for funding this project

Mentorship experiences of doctoral students: Effects on program satisfaction and ideal mentor qualities

The road to doctoral completion is often fraught with barriers, self-doubt, and complications. Creighton, Creighton, and Parks (2010, Mentoring & Tutoring: Partnership in Learning, 18(1), 39-52. doi:10.1080/13611260903448342) asserted that mentoring plays a crucial role in the development and success of graduate students, especially those in doctoral programs. The mentorship of doctoral students can also assist in alleviating the attrition rates that are currently estimated to be between 40% and 60%. In this quantitative study, correlational and stepwise regression analyses were conducted to examine the most beneficial qualities currently enrolled doctoral students find in a mentor and to describe the relationship between the qualities of a mentoring experience and doctoral students’ satisfaction with their program. This study analyzed data collected from currently enrolled doctoral students (n = 339) through the use of online Facebook and LinkedIn doctoral groups. The findings of this study suggested that higher reported levels of program satisfaction were significantly correlated to mentor satisfaction rates. Further, academic and instrumental mentoring scales were reported by respondents to be most beneficial qualities in a mentor. Findings of this study offered evidence that institutional and department leaders of doctoral programs can implement mentoring programs and, moreover, provide faculty members’ opportunities to build mentoring of doctoral students into their faculty loads. Leaders everywhere should recognize the importance of mentorship benefits not only to students, but also to program satisfaction, retention, and degree completion

Generation of fast propagating combustion and shock waves with copper oxide/aluminum nanothermite composites

doi:10.1063/1.2787972Nanothermite composites containing metallic fuel and inorganic oxidizer are gaining importance due to their outstanding combustion characteristics. In this paper, the combustion behaviors of copper oxide/aluminum nanothermites are discussed. CuO nanorods were synthesized using the surfactant-templating method, then mixed or self-assembled with Al nanoparticles. This nanoscale mixing resulted in a large interfacial contact area between fuel and oxidizer. As a result, the reaction of the low density nanothermite composite leads to a fast propagating combustion, generating shock waves with Mach numbers up to 3.We gratefully acknowledge the financial support by U.S. Army, ARDEC, New Jersey and National Science Foundation