America's Army : enhanced brigades.

Mode of access: Internet.

Integrated approach to cavity system seismic evaluation /

Mode of access: Internet.

Experiments on circular arc and flat plate hydrofoils in noncavitating and full cavity flows.

"Department of the Navy. Bureau of Ships. Contract Nonr-220 (12)."

Hypnotically refreshed testimony : enhanced memory or tampering with evidence? /

Mode of access: Internet.

Aviation safety : enhanced requirements can improve commuter pilot training : report to the honorable Robert C. Byrd, U.S. Senate /

"B-228633"--P. 1.

Enhanced clearance of Candida albicans from the oral cavities of mice following oral administration of Lactobacillus acidophilus

Orally administered live Lactobacillus acidophilus was assessed for its capacity to enhance clearance from the oral cavity of DBA/2 mice shown previously to be 'infection prone'. L. acidophilus fed to DBA/2 mice significantly shortened the duration of colonization of the oral cavity compared to controls. Enhanced clearance of Candida albicans correlated with both early mRNA gene expression for interleukin (IL)-4 and interferon (IFN)-gamma and expression of their secreted products in cultures of cervical lymph nodes stimulated with Candida antigen. In addition rapid clearance correlated with higher levels of IFN-gamma and nitric oxide in saliva. Delayed clearance, less pronounced levels of the cytokine response, saliva IFN-gamma and nitric oxide, and later mRNA expression for IL-4 and IFN-gamma relative to feeding with the L. acidophilus isolate were noted in mice fed a different Lactobacillus isolate (L. fermentum). These observations indicate significant variations in individual isolates to activate the common mucosal system.

Biochemical sensor based on a novel all-fibre cavity ring down spectroscopy technique incorporating a tilted fibre Bragg grating

A novel all-fibre cavity ring down spectroscopy technique is proposed where a tilt fibre Bragg grating (TFBG) or long-period grating (LPG) in the cavity provides sensitivity to surrounding medium. Such configuration with an LPG as the representative was theoretically analyzed. Two spectral bands were identified employable for sensing of surrounding refractive index for a weak LPG while only one band existed for a strong LPG. A TFBG, with enhanced sensitivity compared to usual LPGs, was used in a ring down cavity of 1 m constructed with 2 fibre Bragg gratings as the reflectors and the decay time changed from 220 to 450 ns when the TFBG was immersed into water from air.

Enhanced supercontinuum generation using multi-fibre ultra-long Raman cavities

Supercontinuum generation in a TrueWave and SMF fibre based ultra-long Raman fibre laser cavity is investigated experimentally. By including SMF in the ultra-long Raman cavity, bandwidth and flatness can be dramatically improved.

Gamma-shaped long-cavity normal-dispersion mode-locked Er-fiber laser for sub-nanosecond high-energy pulsed generation

We propose the design of a novel ?-shaped fiber laser resonator and apply it to build a long-cavity normaldispersion mode-locked Er-fiber laser which features enhanced functionalities for management and optimization of pulsed lasing regimes. We report the generation of sub-nanosecond pulses with the energy of ~0.5 µJ at a kilohertz-scale repetition rate in an all-fiber system based on the new laser design. A combination of special design solutions in the laser, such as polarization instability compensation in the ultra-long arm of the resonator, intra-cavity spectral selection of radiation with a broadband fiber Bragg grating, and polarization selection by means of a tilted refractive index grating, ensures low amplified spontaneous emission (ASE) noise and high stability of the laser system output parameters.

Gamma-shaped long-cavity normal-dispersion mode-locked Er-fiber laser for sub-nanosecond high-energy pulsed generation

We propose the design of a novel ?-shaped fiber laser resonator and apply it to build a long-cavity normaldispersion mode-locked Er-fiber laser which features enhanced functionalities for management and optimization of pulsed lasing regimes. We report the generation of sub-nanosecond pulses with the energy of ~0.5 µJ at a kilohertz-scale repetition rate in an all-fiber system based on the new laser design. A combination of special design solutions in the laser, such as polarization instability compensation in the ultra-long arm of the resonator, intra-cavity spectral selection of radiation with a broadband fiber Bragg grating, and polarization selection by means of a tilted refractive index grating, ensures low amplified spontaneous emission (ASE) noise and high stability of the laser system output parameters.

Enhanced supercontinuum generation using multi-fibre ultra-long Raman cavities

Supercontinuum generation in a TrueWave and SMF fibre based ultra-long Raman fibre laser cavity is investigated experimentally. By including SMF in the ultra-long Raman cavity, bandwidth and flatness can be dramatically improved.

Enhanced selective aerobic alcohol oxidation through nanoengineered catalyst supports

The selective conversion of alcohols to their carbonyl derivatives is a critical step towards a sustainable chemical industry. Heterogeneous Pd catalysts represent some of the most active systems known, even so further studies into the active species and role of support are required. Through controlling support mesostructure, using non-interconnected SBA-15 and interlinked SBA-16 and KIT-6, we have evaluated the role of pore architecture on supported Pd nanoparticles and their subsequent activity for liquid phase aerobic allylic alcohol selective oxidation.[1,2] These synthesised silica supports exhibit high surface areas (>800 m2g-1), and similar mesopore diameters (3.5 to 5 nm), but differ in their pore connectivity and arrangement; p6mm (SBA-15), I3mm (SBA-16) and I3ad (KIT-6). When evaluated alongside commercial non-mesoporous silica (200 m2 g-1) they promote enhanced Pd dispersion with interpenetrating assemblies providing further elevation. Macropore introduction into SBA-15, producing a hierarchical macro-mesoporous silica (MM-SBA-15), allows control over mesopore length and accessibility which escalates Pd distribution to levels akin to KIT-6 and SBA-16. Controlling dispersion, and likewise nanoparticle size, is thus facilitated through the choice of support and additionally Pd loading, with cluster sizes spanning 3.2 to 0.8 nm. X-ray spectroscopies indicate nanoparticles are PdO terminated with the oxide content a function of dispersion. Kinetic studies allude to surface PdO being the active site responsible, with a constant TOF observed, independent of loading and support. This confirms activity is governed by PdO density, whilst also overruling internal mass diffusion constraints. MM-SBA-15 facilitates superior activity and TOFs for long chain acyclic terpene alcohols due to reduced internal mass transport constraints.

Sensitivity-enhanced fiber optic temperature sensor with strain response suppression

A temperature sensor based on a multimode-singlemode-multimode (MSM) fiber structure has been proposed and experimentally demonstrated. By utilizing the interference between fiber core and cladding modes, temperature measurement is exploited by monitoring the selected resonant dips shift of the transmission spectrum. A high temperature sensitivity of 50.65 pm/ºC is achieved at a certain resonant dip, accompanied by a suppressed strain sensitivity of only 0.587 pm/με. The sensor reveals the advantages of easy fabrication and interrogation, low cost and small axial strain response. © 2013 Elsevier Inc. All rights reserved.

Design, fabrication and characterization of resonant waveguide grating based optical biosensors

The absence of rapid, low cost and highly sensitive biodetection platform has hindered the implementation of next generation cheap and early stage clinical or home based point-of-care diagnostics. Label-free optical biosensing with high sensitivity, throughput, compactness, and low cost, plays an important role to resolve these diagnostic challenges and pushes the detection limit down to single molecule. Optical nanostructures, specifically the resonant waveguide grating (RWG) and nano-ribbon cavity based biodetection are promising in this context. The main element of this dissertation is design, fabrication and characterization of RWG sensors for different spectral regions (e.g. visible, near infrared) for use in label-free optical biosensing and also to explore different RWG parameters to maximize sensitivity and increase detection accuracy. Design and fabrication of the waveguide embedded resonant nano-cavity are also studied. Multi-parametric analyses were done using customized optical simulator to understand the operational principle of these sensors and more important the relationship between the physical design parameters and sensor sensitivities. Silicon nitride (SixNy) is a useful waveguide material because of its wide transparency across the whole infrared, visible and part of UV spectrum, and comparatively higher refractive index than glass substrate. SixNy based RWGs on glass substrate are designed and fabricated applying both electron beam lithography and low cost nano-imprint lithography techniques. A Chromium hard mask aided nano-fabrication technique is developed for making very high aspect ratio optical nano-structure on glass substrate. An aspect ratio of 10 for very narrow (~60 nm wide) grating lines is achieved which is the highest presented so far. The fabricated RWG sensors are characterized for both bulk (183.3 nm/RIU) and surface sensitivity (0.21nm/nm-layer), and then used for successful detection of Immunoglobulin-G (IgG) antibodies and antigen (~1μg/ml) both in buffer and serum. Widely used optical biosensors like surface plasmon resonance and optical microcavities are limited in the separation of bulk response from the surface binding events which is crucial for ultralow biosensing application with thermal or other perturbations. A RWG based dual resonance approach is proposed and verified by controlled experiments for separating the response of bulk and surface sensitivity. The dual resonance approach gives sensitivity ratio of 9.4 whereas the competitive polarization based approach can offer only 2.5. The improved performance of the dual resonance approach would help reducing probability of false reading in precise bio-assay experiments where thermal variations are probable like portable diagnostics.

Hydrogen production by enhanced methane reforming with membrane reactors or with CO2 capture materials

Pure hydrogen production from methane is a multi-step process run on a large scale for economic reasons. However, hydrogen can be produced in a one-pot continuous process for small scale applications, namely Low Temperature Steam Reforming. Here, Steam Reforming is carried out in a reactor whose walls are composed by a membrane selective toward hydrogen. Pd is the most used membrane material due to its high permeability and selectivity. However, Pd deteriorates at temperatures higher than 500°C, thus the operative temperature of the reaction has to be lowered. However, the employment of a membrane reactor may allow to give high yields thanks to hydrogen removal, which shifts the reaction toward the products. Moreover, pure hydrogen is produced. This work is concentrated on the synthesis of a catalytic system and the investigation of its performances in different processes, namely oxy-reforming, steam reforming and water gas shift, to find appropriate conditions for hydrogen production in a catalytic membrane reactor. The catalyst supports were CeZr and Zr oxides synthesized by microemulsion, impregnated with different noble metals. Pt, Rh and PtRh based catalysts were tested in the oxy reforming process at 500°C, where Rh on CeZr gave the most interesting results. On the opposite, the best performances in low temperature steam reforming were obtained with Rh impregnated on Zr oxide. This catalyst was selected to perform low temperature steam reforming in a Pd membrane reactor. The hydrogen removal given by the membrane allowed to increase the methane conversion over the equilibrium of a classical fixed bed reactor thanks to an equilibrium shift effect. High hydrogen production and recoveries were also obtained, and no other compound permeated through the membrane which proved to be hydrogen selective.