Lanthanum halide nanoparticle scintillators for nuclear radiation detection

Nanoparticles with sizesscintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation

A multi-wavelength mid-IR laser based on BaGa4Se7 optical parametric oscillators

A multi-wavelength mid-IR laser consisting of 3.05 μm, 4.25 μm, and 5.47 μm BaGa4Se7(BGSe)optical parametric oscillators (OPOs) switched by DKDP electro-optic switches with one 10 Hz/7.6 ns pumping wave is demonstrated. Maximum energies at 3.05 μm, 4.25 μm, and 5.47 μm are 1.35 mJ, 1.03 mJ, and 0.56 mJ, respectively, corresponding to optical-to-optical conversion efficiencies of 9.4%, 7.6%, and 4.2%. To the best of our knowledge, this study is the first of generation of three mid-IR wavelength lasers using electro-optic switches. Furthermore, this study provides a viable solution for a high-energy or high-power, compact, or even portable multi-wavelength mid-IR laser device that employs a single pumping wave

A Molecular Design Approach Towards Elastic and Multifunctional Polymer Electronics

Next-generation wearable electronics require enhanced mechanical robustness and device complexity. Besides previously reported softness and stretchability, desired merits for practical use include elasticity, solvent resistance, facile patternability and high charge carrier mobility. Here, we show a molecular design concept that simultaneously achieves all these targeted properties in both polymeric semiconductors and dielectrics, without compromising electrical performance. This is enabled by covalently-embedded in-situ rubber matrix (iRUM) formation through good mixing of iRUM precursors with polymer electronic materials, and finely-controlled composite film morphology built on azide crosslinking chemistry which leverages different reactivities with C–H and C=C bonds. The high covalent crosslinking density results in both superior elasticity and solvent resistance. When applied in stretchable transistors, the iRUM-semiconductor film retained its mobility after stretching to 100% strain, and exhibited record-high mobility retention of 1 cm2 V−1 s−1 after 1000 stretching-releasing cycles at 50% strain. The cycling life was stably extended to 5000 cycles, five times longer than all reported semiconductors. Furthermore, we fabricated elastic transistors via consecutively photo-patterning of the dielectric and semiconducting layers, demonstrating the potential of solution-processed multilayer device manufacturing. The iRUM represents a molecule-level design approach towards robust skin-inspired electronics

RIC-7 Promotes Neuropeptide Secretion

Secretion of neurotransmitters and neuropeptides is mediated by exocytosis of distinct secretory organelles, synaptic vesicles (SVs) and dense core vesicles (DCVs) respectively. Relatively little is known about factors that differentially regulate SV and DCV secretion. Here we identify a novel protein RIC-7 that is required for neuropeptide secretion in Caenorhabditis elegans. The RIC-7 protein is expressed in all neurons and is localized to presynaptic terminals. Imaging, electrophysiology, and behavioral analysis of ric-7 mutants indicates that acetylcholine release occurs normally, while neuropeptide release is significantly decreased. These results suggest that RIC-7 promotes DCV–mediated secretion

Synthesis, Characterization and Application of Luminescent Quantum Dots and Microcrystalline Phosphors

Si QDs embedded in SiOx or SiNx thin films, which could emit light in the entire visible range from 440 nm to 840 nm by controlling their size and/or their matrix, were synthesized by evaporation or plasma enhanced chemical vapor deposition techniques. Various shades of white could be obtained from multi-layered SiNx film structures by controlling the size of Si QDs and layer thickness. It was shown that the combination of these films can produce white emission spectra with superior color rendering properties compared to conventional fluorescent tubes. Such Si-based QDs can be used as down-converting phosphors to coat a blue/UV LED to generate white light, providing a less expensive fabrication process to obtain advanced solid state lighting devices. As a supplement, free CdTe QDs with emission colors spanning 520~700 nm and quantum efficiency up to 54%, were synthesized using a colloidal chemical method for white LED applications. White PL and a range of emission colors were obtained from mixed CdTe QD samples excited by a 420 nm blue LED. Another part of this research was to develop a new x-ray powder phosphor, ZnTe:O, for biological imaging applications used in CCD-based synchrotron x-ray detectors. A unique dry synthesis process, including gaseous dry doping and etching procedures, was developed to synthesize ZnTe:O phosphors. The excellent x-ray luminescence results of oxygen doped ZnTe, including high efficiency, high resolution, fast decay, low afterglow and an improved spectral match to the CCD detector, indicated that ZnTe:O is a promising phosphor candidate for x-ray imaging applications.Ph.D.Committee Chair: Summers, Christopher; Committee Co-Chair: Wagner, Brent; Committee Member: Carter, Brent; Committee Member: Ferguson, Ian; Committee Member: Liu, Meili

Scaling tendency prediction in water injection well of K2 formation of C68 block

The K2 formation of C68 block is explored by injecting water to maintain formation pressure, but the continuous decrease of injection rate significantly reduces oil production. Therefore, it is important to predict scaling tendency of injected water in the formation. Firstly, ion composition of formation water and injected water was tested according to recommended practices in petroleum industry. Then, wellbottom temperature distribution of injection wells was simulated under injection water rate requirement of oilfield development. Furthermore, based on the “Oddo-Tomson” prediction model of inorganic scale, the scaling trend of water flooding in K2 formation is predicted according to the possible temperature and pressure. The research indicates that sulfate scale cannot be formed in C68 block and there is a slight possibility of carbonate scaling, which provides a basis to select the correct stimulation technology for increasing production

Algorithmic Approach to a Minimization Problem

We first construct an implicit algorithm for solving the minimization problem minx∈Ω∥x∥ , where Ω is the intersection set of the solution set of some equilibrium problem, the fixed points set of a nonexpansive mapping, and the solution set of some variational inequality. Further, we suggest an explicit algorithm by discretizing this implicit algorithm. We prove that the proposed implicit and explicit algorithms converge strongly to a solution of the above minimization problem

Time-resolved spectral response of asymmetrical optical microcavity structures under laser-driven shock compression

The time-resolved spectral responses of three asymmetrical optical microcavity (AOMC) structures under laser-driven shock compression were investigated. The objective was to compare the performance of these multilayer structures and explore the potential in dynamic shock “pressure” sensing, given their unique ability to capture spatially heterogeneous pressure distributions across 2D surfaces. Different AOMC structures were fabricated, with amorphous SiO2, amorphous Al2O3, and PMMA cavity layers between deposited silver reflecting layers producing the characteristic spectral features of the structures. An experimental setup employing laser-driven shock compression was used to generate nanosecond scale pressure loads of ∼1-10 GPA, and the corresponding time-resolved spectral response and in-situ particle velocity of the AOMCs was simultaneously recorded. Each of the AOMC multilayers showed clear spectral shifts as a function of pressure with nanosecond level correlation to the independently measured velocimetry data. These results indicate that the time-resolved physical state of the cavity layer drives the spectral response of the optical microcavity structures. The results also validate qualitative predictions of the multilayer structures’ response to dynamic compressive loads and their potential for use in time-resolved sensing of pressure

OsmiR396d Affects Gibberellin and Brassinosteroid Signaling to Regulate Plant Architecture in Rice

Genetic improvement of plant architecture is one of the strategies for increasing the yield potential of rice (Oryza sativa). Although great progress has been made in the understanding of plant architecture regulation, the precise mechanism is still an urgent need to be revealed. Here, we report that over-expression of OsMIR396d in rice results in semidwarf and increased leaf angle, a typical phenotype of brassinosteroid (BR) enhanced mutant. OsmiR396d is involved in the interaction network of BR and gibberellin (GA) signaling. In OsMIR396d over-expression plants, BR signaling was enhanced. In contrast, both the signaling and biosynthesis of GA were impaired. BRASSINAZOLE-RESISTANT1, a core transcription activator of BR signaling, directly promoted the accumulation of OsmiR396d, which controlled BR response and GA biosynthesis by regulating the expression of different target genes respectively. GROWTH REGULATING FACTOR 6, one of OsmiR396d targets, participated in GA biosynthesis and signal transduction but was not directly involved in BR signaling. This study provides a new insight into the understanding of interaction between BR and GA from multiple levels on controlling plant architecture