Mixed metal oxide nanowires via solid state alloying.

Mixed metal oxide materials with composition control find applications in energy conversion and storage processes such as heterogenous catalysis, photoelectrochemical catalysis, electrocatalysis, thermal catalysis, and lithium-ion batteries. Mixed metal oxides and/or complex oxides with composition control and in one-dimensional form as nanowires could be interesting to various catalysis applications due to control on single crystal surfaces, active sites, acidity versus basicity site density, and oxygen vacancies. The major challenge is to synthesize mixed metal oxide nanowires beyond binary oxides with composition control. In this dissertation, solid state alloying of binary oxide nanowires with solid and liquid precursors is studied to obtain mixed metal oxide nanowires. Solid state alloying studies were conducted using either solid precursors of hydroxides or liquid precursor of nitrates mixed with the already synthesized binary metal oxide nanowires, dried and solid state diffused under inert atmosphere to achieve the ternary mixed metal oxides or solid solutions of mixed metal oxide nanowires. First and foremost, porous nanowires of binary oxides have been found to be more beneficial for alloying experiments. Several experiments using different precursors and solutes into commonly available binary oxides such as Zinc Oxide (ZnO), Alumina (Al2O3) and Titania (TiO2) were conducted to understand the underlying mechanism. Alloying elements included copper, zirconium, cobalt, nickel, and alkali metals. Experiments suggest that the alloying into nanowires were uniform irrespective of the uniformity of contact with precursor. Results also yielded higher solubilities of solutes into nanowires compared to those predicted from solubility in bulk materials. Specifically, the solubility of solute copper obtained is more than 8 at% for titania and alumina nanowire materials. Based on the thermodynamic phase diagram, this solubility is beyond the thermodynamic bulk solubility for these materials at these process conditions. Extended solubility could be potentially attributed to the available higher surface energy at nanoscale, surface free energy minimization, and thermodynamic stabilization. A mechanism is proposed for alloying with nanowires which suggests that the reaction of precursors with metal oxide nanowires is necessary for solute’s diffusion and alloying. The electrocatalytic behavior of porous tin oxide nanowires was investigated using electrochemical reduction of CO2 to formate. It is concluded that the high-density grain boundary on the nano wire structure is a primary factor in the observed enhancement of the selectivity, rate of HCOOH formation, and associated minimization of the H2 evolution reaction during the electrochemical reduction of CO2. Formic acid formation begins at lower overpotential (350 mV) and reaches a steady Faradaic efficiency of ca. 80 % at only -0.8 V vs. RHE. Nickel alloyed titania nanowires were tested for the effectiveness of single atom catalysis in a dry methane reforming (DMR) application. The activity of nickel alloyed into the titania nanowires displayed superior performance with 96-97% and 83-86% for CO2 and methane conversion, respectively, with no coke deposition after 50 hours. In comparison, the nickel supported on titania nanowires exhibited catalyst activity of 98 those predicted from solubility in bulk materials. Specifically, the solubility of solute copper obtained is more than 8 at% for titania and alumina nanowire materials. Based on the thermodynamic phase diagram, this solubility is beyond the thermodynamic bulk solubility for these materials at these process conditions. Extended solubility could be potentially attributed to the available higher surface energy at nanoscale, surface free energy minimization, and thermodynamic stabilization. A mechanism is proposed for alloying with nanowires which suggests that the reaction of precursors with metal oxide nanowires is necessary for solute’s diffusion and alloying. The electrocatalytic behavior of porous tin oxide nanowires was investigated using electrochemical reduction of CO2 to formate. It is concluded that the high-density grain boundary on the nano wire structure is a primary factor in the observed enhancement of the selectivity, rate of HCOOH formation, and associated minimization of the H2 evolution reaction during the electrochemical reduction of CO2. Formic acid formation begins at lower overpotential (350 mV) and reaches a steady Faradaic efficiency of ca. 80 % at only -0.8 V vs. RHE. Nickel alloyed titania nanowires were tested for the effectiveness of single atom catalysis in a dry methane reforming (DMR) application. The activity of nickel alloyed into the titania nanowires displayed superior performance with 96-97% and 83-86% for CO2 and methane conversion, respectively, with no coke deposition after 50 hours. In comparison, the nickel supported on titania nanowires exhibited catalyst activity of 98-100% and 55-58% for CO2 and methane conversion, respectively, for over 50 hours with deposited carbon on the catalyst surface and sintering of nickel particles observed. In summary, ex-situ alloying of binary oxide nanowires could be used for producing mixed metal oxide nanowires at larger scale. Mixed metal oxide nanowire materials could present model systems for accelerated discovery of new materials and compositions for various catalysis applications

Micro Combustion of Primary Reference Fuels in Narrow Heated Channels

Conventional fuel testing machines like CFR engines require large quantities of fuel. The current study seeks to overcome this limitation by introducing an alternative method using a microscale combustion reactor which consumes relatively small amounts of fuel (100-250 ml). For this reason, Primary Reference Fuels (PRF’s: volumetric mixtures of n-heptane and iso-octane) which are simple surrogates of gasoline are selected to test using micro reactor. The primary goal is to determine the effectiveness of using the micro reactor setup to differentiate fuels of different octane number. Experiments with stoichiometric PRF/air mixtures are performed inside a cylindrical quartz tube of 1mm internal diameter. The fuel-air mixture velocity is varied from 5 to 80 cm/s, and three distinct combustion regimes are observed: weak flames, flames with repetitive extinction and ignition (FREI), and normal flames. In experiments, the extent of CH* chemiluminescence is captured by a monochrome machine vision camera at each set point velocity. In initial tests, wall temperature profiles are measured by a translating thermocouple setup. The experimental setup is subsequently changed to thin filament pyrometry (TFP) to allow for temperature profiles at elevated pressures. Post processing involves the extraction of flame locations to obtain ignition and extinction points. Flame temperatures are extracted from the flame locations using wall temperature profile. Different PRF blends are compared and a larger temperature difference between n-heptane and other PRFs is seen but no clear differentiation is observed from RON 50-100 at 1 atm. However, PRFs tend to show larger differences in ignition and extinction temperatures at higher pressures. To check the feasibility of the micro reactor for newly developed fuels, four fuel samples of different hydrocarbon chains with the same RON are tested in the last part of the work and results show responsiveness to octane sensitivity

Molecular Mechanisms and Inhibition of Transcription Activation by Bacterial AraC Family Activator Proteins

AraC family proteins are transcriptional regulators that are defined by the presence of a conserved DNA binding domain (DBD). My research focused on three AraC family activators: Rns (activator of virulence genes in diarrhea-causing ETEC), VirF (activator of virulence genes in diarrhea-causing Shigella) and RhaR (activator of L-rhamnose catabolic operons in Escherichia coli). With the ultimate goal of discovery of novel antibacterial agents that inhibit the AraC family proteins, here I have investigated the molecular mechanism of transcription activation by Rns and RhaR. Site-directed mutagenesis of residues in the ETEC Rns N-terminal domain (NTD) identified three residues (N15, N16 and I17) that are required for the transcription activation function of Rns. Site-directed mutagenesis of residues in the Rns DBD (predicted to be contacted by the NTD residues) identified three residues (K216, Y251 and G252) that are required for transcription activation, and one residue (H250) that is required for both DNA binding and transcription activation. We propose that transcription activation by Rns involves contacts between RS2 and AS2 region residues and these contacts may impart the structure or dynamics required by Rns to activate transcription. In RhaR, I investigated the role of the RhaR Arm in transmission of the signal that effector (L-rhamnose) is bound from the NTD to the DBD, converting RhaR to its activating state. Site-directed mutagenesis results suggested that the RhaR Arm is involved in maintaining RhaR in its non-activating state. Our results suggest that residue L35 in the Arm makes inter-domain interactions with the RhaR DBD to reduce transcription activation by RhaR in the absence of L-rhamnose. To identify novel agents that target AraC family proteins, I tested the small molecule SE-1, which our lab identified as an effective inhibitor of the AraC family proteins RhaS and RhaR. Despite limited sequence identity, SE-1 was also shown to inhibit VirF and Rns activity in cell-based assays in E. coli. I showed that SE-1 blocked in vitro DNA binding by VirF and Rns, and expression of VirF-dependent virulence genes in Shigella. A collaborator showed that SE-1 inhibited invasion of Shigella into eukaryotic host cells. SE-1 did not detectably inhibit the growth or metabolism of the bacterial or eukaryotic host cells, respectively, indicating that the inhibition of invasion was not due to general toxicity. Overall, SE-1 appears to exhibit selectivity toward AraC family proteins, and has potential to be developed into a novel antibacterial agent

MULTIPLE CHANNEL COHERENT AMPLITUDE MODULATED (AM) TIME DIVISION MULTIPLEXING (TDM) SOFTWARE DEFINED RADIO (SDR) RECEIVER

It is often required in communication and navigation systems to be able to receive signals from multiple stations simultaneously. A common practice to do this is to use multiple hardware resources; a different set of resources for each station. In this thesis, a Coherent Amplitude Modulated (AM) receiver system was developed based on Software Defined Radio (SDR) technology enabling reception of multiple signals using hardware resources needed only for one station. The receiver system architecture employs Time Division Multiplexing (TDM) to share the single hardware resource among multiple streams of data. The architecture is designed so that it can be minimally modified to support any number of stations. The Verilog Hardware Description Language (HDL) was used to capture the receiver system architecture and design. The design and architecture are initially validated using HDL post-synthesis and post-implementation simulation. In addition, the receiver system architecture and design were implemented to a Xilinx Field Programmable Gate Array (FPGA) technology prototyping board for experimental testing and final validation

Functional Exploration of Antisense Long Non-Coding RNAs Containing Transposable Elements: A Bioinformatics Approach

Long non-coding RNA (lncRNAs) show a wide range of regulatory functions at the transcriptional and post-transcriptional levels both in the nucleus and cytoplasm. Recently, antisense lncRNAs (ASlncRNAs) were reported to up-regulate protein synthesis post-transcriptionally through a mechanism depending on an embedded inverted SINE B2 and 5' overlap to the target mRNAs. Such ASlncRNAs are also referred as SINEUPs. Synthetic SINEUPs with identical modular organization were also demonstrated to exert the same activity suggesting a functional relationship between SINE repetitive elements and ASlncRNAs. In order to gain a broader insight on the contribution of transposable elements (TEs) in the sequence composition of ASlncRNAs, I have developed a bioinformatic pipeline that can identify and characterize transcripts containing TEs and analyze TEs coverage for different classes of coding/non-coding sense/antisense (S/AS) pairs. I aimed at identifying if the functional activity of SINEUPs could be a widespread phenomenon across multiple similar natural ASlnRNAs in the transcriptomes of the extensively studied model organisms that have a well annotated catalog of IncNRAs. From my initial analysis I identified human and mouse are the two species that showed a significant coverage enrichment of SINE repeats among ASlncRNAs. I further performed several functional enrichment analysis for the sense coding genes overlapping to ASlncRNAs taking into consideration of different characteristics of the 5' binding domain and the 3' embedded SINE repetitive elements. This permitted me to identify the effect of these modular features over the functional associations of sense coding genes. The results of the analysis showed that the products of coding genes associated to ASlncRNAs containing SINEs are significantly enriched for mitochondrial localization. Further, to determine if these ASlncRNAs could exert SINEUP-like activity during stress, I analyzed the data from a published custom microarray experiment study, that were associated to the polysome fractions of MRC5 cell lysates in control and oxidative stress condition. The results revealed that the ASlncRNA carrying inverted or direct SINE repeats and their corresponding sense coding genes do not show any significant differential polysome loading in stress with respect to normal conditions, which is not a desired characteristic of a potential SINEUP. However, ASlncRNAs with inverted and direct SINE repeats corresponding to high translating polysome fractions showed a significantly higher ratio of means for RNA levels in stress over control, in contrast to noASlncRNA. This suggests that the ASlncRNA containing SINE elements are the key RNA molecules that are active during stress, although to determine if they are also involved in the increased polysome loading of their respective sense coding mRNAs, there is a need of further experimentation and exploration. Altogether, the work presented in this thesis provides a novel bioinformatics approach to study transcriptome-wide ASlncRNAs containing TEs and their functional association over the sense coding genes, and discover new significant functional features of ASlncRNA to be biologically validated

Implementing X.509 security certificate based authentication in a virtual organization

Title from PDF of title page (University of Missouri--Columbia, viewed on May 24, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Gordon K. SpringerIncludes bibliographical references."July 2011"In recent years, research institutions have shown great interest in forming Virtual Organizations (VO) as a cost effective alternative to maintaining dedicated resources for computationally intensive tasks. Shibboleth is an infrastructure used to provide the facility of single sign-on in many VOs. However, implementation of the Shibboleth infrastructure is a huge challenge that entails conformance to the policies of the institution that participates in the VO. Therefore in the absence of a Shibboleth authentication mechanism at a user's home institution, it may not be possible for users of a participating institution to access resources belonging to other institutions in the VO. This thesis addresses the issue of authenticating users who do not possess Shibboleth credentials, but are authentic users that need access to the resources in a VO. Lately, X.509 security certificates have gained immense popularity as a method for verifying the identity of a person. These certificates can be used to authenticate users on any system that trusts the certificate's signing Certificate Authority. Incorporating support for certificate-based authentication in the VO helps to authenticate users that belong to the research environment, but do not necessarily have Shibboleth credentials. Thus, certificate-based authentication increases the resource providing capability of the research environment by servicing all the users that are entitled to use resources in the VO

Merchandise Returns predictability

The present disclosure pertains to the field of payment processing and predictive modelling for the Merchandise returns transactions in the context of payment transactions. More specifically, it focuses on developing a new model that offers predictability scores for merchandise returns, allowing merchants and acquirers to make informed decisions about the clearing of the original transactions. This innovative solution leverages historical data and employs linear regression to predict likelihood of a potential merchandise returns, potentially saving huge costs and resources for the merchant and acquirer and all the parties involved in the transaction processing

Novel Proportionate Scrutiny On Crop Protection From Creatures By Deep Learning

The main objective of this paper is to protect the crop from animal attacks. The conventional techniques have the same kind of security applied to all the types of animals detected based on a Passive IR sensor, and only single-stage protection is applied. The images were captured and identified with the help of machine learning and deep learning techniques. The project was designed with a rectangular farm area. On each side of the entrance, the device was installed to capture the image for processing to identify the animals, based on the animal identification, different levels of security were applied, and that will produce different sounds with different Db levels and variety of dazzling light. This work provides a comprehensive description of the design, development, and assessment of an intelligent animal repelling system that allows for to detection and recognition of the animals. The enhancement is done by different levels of protection and different types of protection based on the classified animals. In initial level protection, making the noise and lightning from the opposite side send the animal out of the farm. If the animals are still on the farm, initiating the next stage that the image will send to the owner. The accuracy of all the methods discussed will be compared based on the complexity of the technique, implementation cost, reciprocating time, and accuracy of animal detection. In recent years, edge computing has become an essential technology for real-time application development by moving processing and storage capabilities close to ending devices, thereby reducing latency, improving response time, and ensuring secure data exchange