Physiological and genetic changes in poplar during mycorrhizal colonization under phosphorus limitation

Poplar species and hybrids are intensively cultivated as renewable sources of biomass because of their rapid growth, extensive genetic variation and ease of propagation. However, the physiological mechanisms underlying soil stress resistance within these poplar species and hybrids are not yet understood. With the recent sequencing of the poplar genome, the use of this species in physiological stress resistance studies may help elucidate the underlying basis of stress resistance in a woody species. Further, although symbiotic mycorrhizal associations have farreaching ecological significance in forest ecosystems, our understanding of the influences of the association on the genetic basis of environmental stress resistance of trees, including poplar, is limited.;In this dissertation research, physiological, ecophysiological, proteomic and plant biochemistry approaches were used to understand the role of the plant-mycorrhizal symbiotic association under P limitation. By using advanced technology, such as proteomics including two-dimensional gel electrophoresis, in association with physiological measures, my research has aimed to understand the role of the mycorrhizal association in tree stress physiology, which has global implications..;My objective for the first chapter was to test if the association of the ectomycorrhizal fungus Laccaria bicolor (Marie) with aspen (Populus tremuloides Michx.) would alter the plant response to environmental phosphate (Pi) limitation. To test this, we studied different stress related oxidative enzymes, such as catalase and superoxide dismutase, carbon allocation of above and below ground biomass, tissue P accumulation, and root exudation of organic acids. The symbiotic association improved P acquisition in aspen and reduced the oxidative stress responses as well as the exudation responses generated by P limitation. The results confirmed that the acclimation responses of aspen in association with Laccaria bicolor under Pi limitation were mediated through enhanced Pi uptake resulting from the symbiotic association.;In the second chapter, I assessed a broader set of physiological changes in aspen under P limitation due to the different ectomycorrhizal species, Laccaria bicolor and Paxillus involutus. I hypothesized that aspen would have more carbon demand belowground due to mycorrhizal colonization and, to meet this demand, carbon assimilation would increase. Secondary metabolites are also indicators of stress and glycosides in aspen are well defined (Chen et al. 2009). Hence I assayed the secondary metabolites in different plant tissues. As the two fungal species differ in their occurrence, we expected their behavior to differ for the ecophysiological and secondary metabolite parameters. In this study, I found that P limitation significantly limits photosynthetic gas exchange as well as the biochemistry of photosynthesis, but primarily in nonmycorrhizal aspen. These changes were correlated with reductions in tissue P levels that were pronounced in nonmycorrhizal plants.;Finally, to gain a better understanding of the molecular mechanisms of the mycorrhizal symbiotic association, I used proteomic approaches to evaluate the proteins involved in this interaction. The analysis of the proteins that were differentially displayed during ectomycorrhizal and arbuscular mycorrhizal association visualized by two-dimensional electrophoresis (2-DE) of the total protein obtained from poplar roots non-inoculated and associated with two ectomyccorhizal fungi L. bicolor and P. involutus and one arbuscular myccorhizal fungus Glomus intrradices , were analyzed. I found significant changes in protein abundances in many metabolic pathways, including those associated with energy, general metabolism, and stress response induced by the arbuscular and ectomycorrhizal association. Similarities and differences between the two groups of fungi suggest that there may be both conserved and unique plant responses to mycorrhizal colonization.;By using the different tools of physiology, ecophysiology, plant biochemistry and proteomics, I attempted to build a broad understanding about the symbiotic association. This research will help to accelerate our understanding of the plant-soil interface and tree stress physiology, which in turn can aid in our understanding of forest ecosystem productivity and response to future changes in the environment. (Abstract shortened by UMI.)

Silver Nanoparticles- a versatile therapeutic and biomimetic intervention in dentistry: A Systematic Review

Background: Nanotechnology advances have been changing the face of dentistry with its diverse range of dental applications. Silver nanoparticles (AgNPs) is a relatively newer breakthrough in dentistry. AgNPs, an antimicrobial agent have been incorporated into various biomaterials in order to reduce the biofilm formation and lends a cariostatic effect thus giving a biomimetic. Aim: This systematic review is aimed to provide an overview of Silver nanopartiocle application in dentistry and its roles as a biomimetic agent in preventing various oral diseases

Preparation and Characterization of a Ferrocene Containing Main-Chain PEG-CNT Phase for Hybrid Supercapacitor Application

With the rapid development of the global economy, the depletion of fossil fuels, and increasing environmental pollution, there is an urgent need for new technologies associated with energy conversion and storage. Supercapacitors have attracted tremendous attention and are now extensively used for energy storage. They charge and discharge quickly for high power demands but have low energy density. The goal of the research was to synthesize electrode and electrolyte materials for the fabrication of a hybrid supercapacitor cell with high energy density. In this hybrid cell, carbon nanotubes were used as electrodes, which contribute to electrostatic capacitance, and redox polymer was used as an electrolyte which accounts for redox or faradaic capacitance, thus increasing the energy density. For the reduction half-cell, ferrocene dicarboxylic acid was polymerized with polyethylene glycol phase for an electrolyte. The electrolyte for oxidation half-cell was viologen-PEG polymer, prepared by a laboratory colleague, Rana Kanishka. The hybrid cell using these materials was fabricated in a sandwich model configuration. Further, electrochemical experiments were employed for assessing the performance of the cell. In conclusion, the electrode and electrolyte materials showed excellent electrochemical behavior and were appropriate for this type of hybrid cell

Chemically Patterned Surfaces as Test Platforms to Study Magnetic and Solvent-Responsive Properties at the Nanoscale: Investigations Using Scanning Probe Microscopy

Chemically patterned surfaces were fabricated using a combination of molecular self-assembly and particle lithography to generate billions of nanostructures of organosilane self-assembled monolayers (SAMs). Monodisperse mesospheres were used as surface masks to prepare nanostructures on flat surfaces using the simple benchtop chemistry steps of mixing, centrifuging, evaporation, and drying. Periodic arrays of well-defined organosilane nanostructures serve as discrete surface sites for the selective deposition of polymers and magnetic nanoparticles. In this dissertation, particle lithography approaches for surface patterning provide new directions for studying surface chemistry at the molecular-level using high resolution investigations with scanning probe microscopy (SPM). Atomic force microscopy (AFM) can be used to analyze samples in ambient and liquid environments. The solvent responsive nature of OTS nanostructures were investigated using in-situ liquid imaging with AFM. AFM provides unique capabilities for molecular visualization and ultrasensitive measurements of changes in heights, widths and surface coverage of the swollen OTS nanostructures with nanoscale resolution. Ring nanostructures of OTS presented a 3D interface for studying the interaction of solvents at the molecular level. The vibrational response of patterned magnetic Fe3O4 nanoparticles in response to an applied external magnetic field was detected using magnetic sample modulation AFM (MSM-AFM). The vibration of Fe3O4 nanoparticles can be detected with a nonmagnetic AFM tip operated in continuous contact mode. In MSM-AFM, an AC current applied to the wire coil solenoid within the special sample plate drives the actuation of magnetic nanomaterials that are attached to surfaces. The magnetic Fe3O4 nanoparticles were induced to vibrate in the presence of externally applied electromagnetic field. Parameters such as frequency and magnetic field strength can be tuned in-situ to study dynamic changes in the vibrational response of samples. The AFM tip serves as a force and motion sensor for mapping the vibrational response of magnetic nanomaterials. The information acquired from MSM images includes the distribution of individual magnetic domains as well as spectra of the characteristic resonance frequencies of the vibrating magnetic nanomaterials

Segmentation cracks in plasma spray coatings: Formation dynamics and chracterization

Segmentation cracks in Air Plasma Sprayed (APS) Thermal Barrier Coatings (TBCs) have been recognized as crucial micro-structural asset for increasing the in-plane strain tolerance of the coatings and thus enhancing the TBC durability. These vertically cracked coatings also show excellent in-plane fracture toughness. This combination has allowed wide spread use of these coatings in gas turbine engines. Although industrially successful, there is limited scientific studies on the formation dynamics of such cracks, and their relationship to process conditions and performance. This is especially of importance as efforts are underway to find alternative to Yttria Stabilized Zirconias for higher temperature thermal barrier applications. Please click Additional Files below to see the full abstract

Moodboard: A Digital Solution for the Work-Life Balance in an Advertising Agency

The long working hours prevalent in the advertising industry is a well-known fact. It has become a common practice in agencies for quite a while now, leading to work-life imbalance for employees. The advertising agencies follow this practice, not because of its effectiveness, but because that’s what everyone else does. They completely ignore the fact that short breaks from work can increase productivity. A common belief of the industry is that the more nights/weekends you spend at work, the more productive you are. Research proves such work stress affects your personal life and health. The goal of this thesis is to help the employees of advertising agencies to have a better work-life balance. The work-life balance in this context is defined as having a happier professional life which does not affect your personal life in a negative way. This will further lead to better creativity and productivity. “If you cannot measure it, you cannot improve it.”– Lord Kelvin This quote states that what you can measure, has room for improvement. Similarly, the basis of this digital mood tracker will be offering a way to measure company morale. The proposed solution is a tracker of employee’s moods at work by using facial recognition technology. The employees can also express appreciation and thank each other in the form of points. These points can be redeemed for discounts on activities beyond work. Self-awareness of moods and expressions of appreciation inside the company could boost company morale. The company morale graph would be derived from the data collected on the digital display. Similarly, the employers can take necessary actions if results show a lower company morale. It will help keep the employees healthier and happier at work while serving as a beneficial tool for both the employers and the employees

Rail passenger knowledge and its impact on information requirements

The rail industry in Great Britain aims to provide value for money by improving customer service and journey satisfaction for passengers, particularly given the rising cost of rail travel. There is increased innovation in several areas, including the personalisation of information, automatic delay repayment, the provision of on-board Wi-Fi, and importantly, the successful management of disruption. The enhancement of disruption information is a key area of investment and research within the industry. The aim of this project was to investigate the current landscape of information provision during rail travel with a focus on increasing its appeal to all passengers, principally during disruption. Specifically, the main objective was to understand how academic theories of expertise and passenger behaviour can aid in improving the design of the content and delivery of rail information to passengers. Following the review of existing research around information provision and passenger experience, interviews were conducted with both rail passengers and service providers to discuss the main themes found in the literature. The aim was to gain an understanding of the main challenges surrounding information provision, particularly with regards to adapting to differing levels of customer knowledge. It was noted that there were key differences seen – both from the literature and the interviews – between frequent and infrequent travellers, which could be attributed to being a product of extensive travel experience, or expertise. At this point, the first step taken was to investigate these differences in a large-scale manner, with a specific focus on the way in which knowledge and experience impacted information use. For this purpose, three different types of surveys were designed and administered. The first, an online survey, was used to examine the information preferences of travellers, alongside their assessments of their own level of expertise regarding rail journeys, and their travel frequency. Results showed that expertise and travel frequency seemed to only account for some of the variance in the preferences for different types of rail information. However, rail information was grouped into six distinct categories according to participant ratings, with some types of information being rated significantly higher than others. This was followed by a repertory grid study and an online survey. This study aimed to look at expertise and travel frequency as well, but with an examination of disruption support, as opposed to generalised rail information. Results confirmed the distinct differences between self-rated expertise and ratings of travel frequency – while most people seemed to consider themselves as being fairly knowledgeable regarding rail travel, there were clearer differences seen with regards to the more objective assessment of their travel frequency. Particularly, frequent travellers understand the nuances of disruption information better – identifying both “good” and “bad” features of disruption alerts – as opposed to less/infrequent travellers, who only focused on the uncertainty created by the disruption alerts. Additionally, four important characteristics of disruption information were identified. The final survey – a vignette experiment – aimed to look at expertise and frequency, in addition to other aspects of rail travel. The aim was to identify the impact of other factors that could be contributing to information use and disruption management. Two variables were selected: journey purpose and the level of familiarity that one has with their trip. Hypothetical disruption scenarios were presented to participants, with the variation of these factors. This was followed by the rating of the six main types of rail information gathered from the online survey, and the four key disruption characteristics obtained from the repertory grid survey. These were rated based on their “usefulness” within the hypothetical disruption situation. The findings were surprising. There was limited influence of the variables examined, with distinct preferences for specific types of information seen across all passengers, regardless of the factors presented, or their expertise or travel frequency. When it comes to disruption management, it seems to be that everyone’s preferences for informational support are the same. The main theoretical impact of this thesis was with regards to the study of expertise in itself. Expertise, simply put, is hard to study. Travel frequency, on the other hand, is not. This thesis contributes evidence towards the notion of expertise being a product of experience and practice, making frequency of travel an appropriate proxy for the study of expertise within dynamic travel environments. From an industry perspective, these findings led to the development of an information provision template that outlines the basic areas to be covered when presenting information to rail passengers, within both general travel situations, as well as during the occurrence of a disruptive event. This template can be used as a guidance checklist for the development of all forms of information systems, from mobile applications to on-board information screens to station displays. This thesis concludes with recommendations for the application of these findings, and for future research within this area

Smooth flexible models of nonhomogeneous Poisson processes fit to one or more process realizations

Simulation is a technique of creating representations or models of real world systems or processes and conducting experiments to predict behavior of actual systems. Input modeling is a critical aspect of simulation modeling. Stochastic input models are used to model various aspects of the system under uncertainty including process times and interarrival times. This research focuses on input models for nonstationary arrival processes that can be represented as nonhomogeneous Poisson processes (NHPPs). In particular, a smooth flexible model for the mean-value function (or integrated rate function) of a general NHPP is estimated. To represent the mean-value function, the method utilizes a specially formulated polynomial that is constrained in least-squares estimation to be nondecreasing so the corresponding rate function is nonnegative and continuously differentiable. The degree of the polynomial is determined by applying a modified likelihood ratio test to a set of transformed arrival times resulting from a variance stabilizing transformation of the observed data. Given the degree of polynomial, final estimates of the polynomial coefficients are obtained from original arrival times using least-squares estimation. The method is extended to fit an NHPP model to multiple observed realizations of a process. In addition, the method is adapted to a multiresolution procedure that effectively models NHPPs with long term trend and cyclic behavior given multiple process realizations. An experimental performance evaluation is conducted to determine the capabilities and limitations of the NHPP fitting procedure for single and multiple realizations of test processes. The method is implemented in a Java-based programming environment along with a web interface that allows user to upload observed data, fit an NHPP, and generate realizations of the fitted NHPP for use in simulation experiments

Microcontroller Based Self-Regulating Devices in Enclosed Environments

Recent times have witnessed developments in the integration of wireless communication and sensing, along with electronic programmable controller devices in real-time operating systems. Intelligent devices incorporate ambient intelligence into enclosed environments by compiling the information received by wireless sensors and providing necessary feedback. This paper analyses the ubiquitous devices with smart sensing technology by casting its assimilation, thereby modelling the actualization of an intelligent environment. Further, we propose a prototype environment using adept embedded system based devices