Fiber Optic Sensors for Energy Applications under Harsh Environmental Conditions

Real-time monitoring physical and chemical parameters in next generation energy-production system is of significant importance to improve the efficiency and reduce the emission for a wide range of applications. Traditional electrical point sensors have limited utilities for direct measurements at high temperature or in highly reactive and corrosive environment. Given the resilience at high temperatures, immunity to electromagnetic interference and intrinsic explosion proof in combustion gas, fiber optic sensors open up opportunity to perform various measurements in energy applications under harsh environments. In this thesis, both chemical and physical sensors were demonstrated to explore the potential of fiber optic sensors in energy industry. The first scheme is fiber optic chemical gas sensing enabled by nanostructured functional metal oxides. A scalable manufacturing approach was developed to produce nano-porous metal oxides with the refractive index tailored to match the optical fiber material. Combined with this functional semiconducting metal oxides, fiber optic chemical sensors with high selectivity and sensitivity was developed using both D-shaped fiber and single crystal sapphire fiber. The sensors performed accurate hydrogen measurement at a record-high temperature of 800 deg C. The second scheme covers a high temperature distributed sensing using Rayleigh backscatter based optical frequency domain reflectometry. Ultrafast laser direct writing method was used to enhance the in-fiber scattering signal and high-temperature stability. Due to the high signal-to-noise ratio and thermal stability of the inscribed nanogratings in the fiber, real-time monitoring of temperature distribution in the operational solid oxide fuel cell was achieved with 5-mm spatial resolution at 800 deg C. In the third scheme, a multi-point sensing system for thermal dynamics monitoring of lithium-ion battery assembly was demonstrated using multimode random air hole fibers infiltrated with quantum dots. The photoluminescence intensity dependence on the ambient temperatures were used to gauge the local operational temperature of lithium-ion batteries. Multi-point temperature sensing systems were developed by bundling quantum dots infiltrated random air hole fibers together. The temperature of the batteries can be real-time monitored using a low-cost UV diode laser as light source and a cellular phone CCD camera as detector

Does judicial foreclosure procedure help delinquent subprime mortgage borrowers?

We conduct comprehensive analyses on whether and how the judicial foreclosure procedure helps subprime mortgage borrowers to reinstate their delinquent loans outside foreclosure liquidation. Even though the transition rates of various exit types are all higher in non-judicial states, we argue such higher rates can be mechanically driven by the faster shrinking pool of delinquent mortgages in non-judicial states over time. Based on the cumulative proportions of various exit types during a period of up to 5 years post the mortgage first become 90 days past due, we find that judicial states offer more opportunities for delinquent borrowers to reinstate their loans outside foreclosure liquidation, especially during a housing market downturn. Cures, modifications, and paid-offs were all important alternative ways to resolve serious delinquencies during 2007–2008. After modifications became widely available in 2009, loan modifications became the most important alternative for subprime borrowers to reinstate their delinquent mortgages outside foreclosure liquidation. The lion\u27s share of the judicial foreclosure benefit shows up after the start of the foreclosure process

Involvement of C2H2 zinc finger proteins in the regulation of epidermal cell fate determination in Arabidopsis

Cell fate determination is a basic developmental process during the growth of multicellular organisms. Trichomes and root hairs of Arabidopsis are both readily accessible structures originating from the epidermal cells of the aerial tissues and roots respectively, and they serve as excellent models for understanding the molecular mechanisms controlling cell fate determination and cell morphogenesis. The regulation of trichome and root hair formation is a complex program that consists of the integration of hormonal signals with a large number of transcriptional factors, including MYB and bHLH transcriptional factors. Studies during recent years have uncovered an important role of C2H2 type zinc finger proteins in the regulation of epidermal cell fate determination. Here in this minireview we briefly summarize the involvement of C2H2 zinc finger proteins in the control of trichome and root hair formation in Arabidopsis .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109574/1/jipb12221.pd

Fiber-optic flow sensors for high-temperature environment operation up to 800°C

This Letter presents an all-optical high-temperature flow sensor based on hot-wire anemometry. High-attenuation fibers (HAFs) were used as the heating elements. High-temperature-stable regenerated fiber Bragg gratings were inscribed in HAFs and in standard telecom fibers as temperature sensors. Using in-fiber light as both the heating power source and the interrogation light source, regenerative fiber Bragg grating sensors were used to gauge the heat transfer from an optically powered heating element induced by the gas flow. Reliable gas flow measurements were demonstrated between 0.066 m∕s and 0.66 m∕s from the room temperature to 800°C. This Letter presents a compact, low-cost, and multiflexible approach to measure gas flow for high-temperature harsh environments. Gas flow measurement plays important roles in various industrial sectors. It provides vital information for a large number of applications such as process controls, fossil fuel and nuclear electric power generation, transportation, and environment monitoring. To perform flow measurements, a large number of flow sensors based on various mechanical, electronic, and microelectromechanical system (MEMS) structures [1] have been developed. These sensors can perform effective flow measurements at room temperature or slightly elevated temperatures (e.g., <200°C). However, a number of industrial and aerospace applications demand flow sensors with much higher operational temperatures (>500°C). These are not attainable by current state-of-the-art technology, such as MEMS. To address this technical challenge, this Letter presents a low-cost and compact all-optical-fiber flow sensing technique that can provide rapid and accurate gas flow measurements from room temperature to 800°C. This is, to our best knowledge, the highest operational temperature for a flow sensor. Fiber-optic sensors are well-known for their resilience in many harsh conditions including in high-temperature, corrosive, and strong electromagnetic environments. Over the last decade, various optical-fiber-based flow sensors have been reported, largely based on two schemes: fiber optical interferometry Compared with electrically heated HWA flow sensors, fiber-optic sensors can also be heated optically to perform flow measurements. Using various optical coupling schemes In this Letter, we demonstrate an all-fiber hightemperature flow sensor using the optical HWA rated for 800°C operation. The sensor consists of an in-fiber optical heating element using high-attenuation fibers (HAFs). High-temperature-stable regenerated FBGs (RFBG

Me-Better Drug Design Based on Nevirapine and Mechanism of Molecular Interactions with Y188C Mutant HIV-1 Reverse Transcriptase

In this paper, the Y188C mutant HIV-1 reverse transcriptase (Y188CM-RT) target protein was constructed by homology modeling, and new ligands based on nevirapine (NVP) skeleton were designed by means of fragment growth. The binding activity of new ligands to Y188CM-RT was evaluated by structural analysis, ADMET prediction, molecular docking, energy calculation and molecular dynamics. Results show that 10 new ligands had good absorbability, and their binding energies to Y188CM-RT were significantly higher than those of wild-type HIV-1 reverse transcriptase(wt). The binding mode explained that fragment growth contributed to larger ligands, leading to improved suitability at the docking pocket. In the way of fragment growth, the larger side chain with extensive contact at terminal is obviously better than substituted benzene ring. The enhancement of docking activity is mainly due to the new fragments such as alkyl chains and rings with amino groups at NVP terminal, resulting in a large increase in hydrophobic bonding and the new addition of hydrogen bonding or salt bonding. This study is expected to provide reference for the research on non-nucleoside reverse transcriptase inhibitors resistance and AIDS treatment