Second Harmonic Generation from Phononic Epsilon-Near-Zero Berreman Modes in Ultrathin Polar Crystal Films

Immense optical field enhancement was predicted to occur for the Berreman mode in ultrathin films at frequencies in the vicinity of epsilon near zero (ENZ). Here, we report the first experimental proof of this prediction in the mid-infrared by probing the resonantly enhanced second harmonic generation (SHG) at the longitudinal optic phonon frequency from a deeply subwavelength-thin aluminum nitride (AlN) film. Employing a transfer matrix formalism, we show that the field enhancement is completely localized inside the AlN layer, revealing that the observed SHG signal of the Berreman mode is solely generated in the AlN film. Our results demonstrate that ENZ Berreman modes in intrinsically low-loss polar dielectric crystals constitute a promising platform for nonlinear nanophotonic applications

Stainless Steel Reinforcement as a Replacement for Epoxy Coated Steel in Bridge Decks

The performance of different types of reinforcement in concrete bridge decks is evaluated in this study. Application of deicing salts has directly led to deterioration of roadway bridge decks due the corrosion of reinforcing steel. Epoxy-coated reinforcement (ECR) is currently the most commonly used alternative in this application; however, it does not guarantee a long lifespan. In some cases, poorly adhering epoxy coatings have resulted in increased corrosion rates, which is a concern for all epoxy coatings. As a comparison, two types of stainless reinforcing steel are evaluated; a 2304 duplex stainless steel and NX-SCRTM stainless steel clad bars, alongside conventional reinforcement and ECR. Upon the completion of testing, the projected cost of each system will be calculated to determine if the increased initial costs can be justified over a design life. Two tests are performed on specimens – a 15 week rapid macrocell test and a series of 96 week bench-scale tests. Completed test results for the rapid macorcell tests are presented, while bench-scale tests are partially completed with specimens aged 26-31 weeks. Results have shown that ECR and stainless steel reinforcement perform better in test media than conventional reinforcement. Pickling 2304 duplex stainless steel bars has a considerable effect on the performance of test specimens, with as-received bars failing ASTM A955 limits on corrosion rates in rapid macrocell and cracked beam tests. Repickling a series of specimens for rapid macrocell testing resulted in a passing of these test limits. Bending stainless steel clad reinforcement did not cause the specimens to exceed the maximum corrosion rate threshold to be surpassed in rapid macrocell testing, while corrosion initiation has not yet occurred in Southern Exposure specimens. Upon initiation, chloride contents at the level of reinforcement are lowest for conventional steel and highest for damaged stainless steel clad specimens

Strong Coupling of Epsilon-Near-Zero Phonon Polaritons in Polar Dielectric Heterostructures

We report the first observation of epsilon near zero (ENZ) phonon polaritons in an ultrathin AlN film fully hybridized with surface phonon polaritons (SPhP) supported by the adjacent SiC substrate. Employing a strong coupling model for the analysis of the dispersion and electric field distribution in these hybridized modes, we show that they share the most prominent features of the two precursor modes. The novel ENZ-SPhP coupled polaritons with a highly propagative character and deeply sub-wavelength light confinement can be utilized as building blocks for future infrared and terahertz (THz) nanophotonic integration and communication devices

Corrosion Performance of Poorly Pickled Stainless Steel Reinforcement

XM-28 (UNS S24100) and 2304 (UNS S32304) stainless steel reinforcing bars with different levels of pickling were evaluated for corrosion resistance using the rapid macrocell and cracked beam tests outlined in ASTM A955. Two heats of XM-28 from the same producer were evaluated using the rapid macrocell test. A single heat of 2304 was evaluated in two conditions; as-received from the manufacturer and re-pickled using both ASTM A955 tests. The poorly pickled heat of XM-28 reinforcement failed the rapid macrocell test with a peak individual corrosion rate exceeding 16 µm/y, while the properly pickled heat passed with no significant corrosion measured. The poorly pickled 2304 reinforcing steel failed the macrocell and cracked beam tests, with peak corrosion rates of 1.07 and 6.48 µm/y, respectively, while upon re-pickling, the same heat of steel passed both tests. These results suggest the need for a method to verify that the pickling process has been performed properly. Performance during the first week of the rapid macrocell tests or requiring that the bars exhibit a bright, shiny, uniformly light surface represent two potential methods for establishing the adequacy of pickling

Stainless Steel Reinforcement as a Replacement for Epoxy Coasted Steel in Bridge Decks

The use of deicing salts in the United States has resulted in the steady deterioration of roadway bridge decks due to the corrosion of reinforcing steel. Since the middle 1970s, the principal corrosion protection techniques for bridge decks have involved the use of epoxy-coated reinforcement (ECR) and increased cover over the reinforcing bars. The combination has greatly lengthened the life of bridge decks, but does not represent a perfect solution. The higher cover increases the bridge dead load and the cost of construction. Epoxy-coated reinforcement adds only slightly to the cost of bridge construction, but there are a number of well-documented cases in both the field and laboratory in which poorly adhering epoxy coatings have actually increased corrosion problems, and there is evidence that all epoxy coatings will eventually be susceptible to those shortcomings. As a result of these concerns, a number of other protective measures have been developed or are under development. These include the use of denser concretes, corrosion inhibitors, and corrosion-resistant steel alloys. Among the latter are various types of stainless steel, including 2304 duplex stainless steel and stainless steel clad reinforcing bars. Based on earlier studies, stainless steel reinforcement is generally less susceptible to corrosion than conventional and epoxy-coated reinforcement, but all stainless steels do not provide the same level of protection and their superiority to ECR has not been clearly demonstrated in all cases. 2304 duplex reinforcing bars and NX-SCR™ stainless steel clad bars (the only stainless steel clad reinforcement that was commercially available in the U.S. at the initiation of this study) have not undergone the same level of testing as other solid stainless steels and prototype clad bars in environments similar to those found in bridge decks. Combined with the additional initial cost of stainless steel compared to epoxy-coated reinforcement, there is a need to quantify the costs and benefits of using stainless steel reinforcement as a replacement for epoxy-coated steel in bridge decks

Local delivery of nitric oxide: Targeted delivery of therapeutics to bone and connective tissues

Non-invasive treatment of injuries and disorders affecting bones and connective tissue is a significant challenge facing the medical community. A treatment route that has recently been proposed is nitric oxide (NO) therapy. Nitric oxide plays several roles in physiology with many conditions lacking adequate levels of NO. As NO is a radical, localized delivery via NO donors is essential to promoting biological activity. Herein, we review current literature related to therapeutic NO delivery in the treatment of bone, skin and tendon repair

A10 – Human Factors Considerations of UAS Procedures and Control Stations: Tasks PC-1 through PC-3 Pilot and Crew (PC) Subtask, Recommended Requirements and Operational Procedures

The Alliance for System Safety of UAS through Research Excellence (ASSURE) conducted research focused on minimum pilot procedures and operational practices used by unmanned aircraft systems (UAS) operators today for the purpose of developing recommendations. This research recommends four pilot and 46 operational minimum procedures to operate a civil single-engine, fixed-wing, single-pilot-configured UAS flying in beyond visual line-of-sight (BVLOS) conditions. These recommendations are anticipated to support potential future aircrew procedure requirements for UAS larger than 55 lbs. operating in the National Airspace System (NAS). These procedures were validated using representative Control Stations in simulated environments

Mathematical modelling of a liver hollow fibre bioreactor

A mathematical model has been developed to assist with the development of a hollow fibre bioreactor (HFB) for hepatotoxicity testing of xenobiotics; specifically, to inform the HFB operating set-up, interpret data from HFB outputs and aid in optimizing HFB design to mimic certain hepatic physiological conditions. Additionally, the mathematical model has been used to identify the key HFB and compound parameters that will affect xenobiotic clearance. The analysis of this model has produced novel results that allow the operating set-up to be calculated, and predictions of compound clearance to be generated. The mathematical model predicts the inlet oxygen concentration and volumetric flow rate that gives a physiological oxygen gradient in the HFB to mimic a liver sinusoid. It has also been used to predict the concentration gradients and clearance of a test drug and paradigm hepatotoxin, paracetamol (APAP). The effect of altering the HFB dimensions and fibre properties on APAP clearance under the condition of a physiological oxygen gradient is analysed. These theoretical predictions can be used to design the most appropriate experimental set up and data analysis to quantitatively compare the functionality of cell types that are cultured within the HFB to those in other systems