Performance differentials of agglomeration and strategic groups: a test of incubation and new venture strategy

Our paper investigates how nascent firms ‘performance is affected by strategic group membership and industrial agglomeration. Agglomeration is defined using geographical concentration while strategic groups are measured as incubated firms that belong to the industry most highly represented within an incubator. Results reveal that incubated firms in counties with higher levels of agglomeration experience a lower hazard of exit. Similarly, incubated firms that belong to a strategic group have a lower hazard of exit. However, the combined effects of agglomeration and strategic group membership based on a three-way interaction between incubation, agglomeration, and strategic group membership leads to an increased hazard of exit

Doctor of Philosophy

dissertationMonitoring and remediation of environmental contaminants (biological and chemical) form the crux of global water resource management. There is an extant need to develop point-of-use, low-power, low-cost tools that can address this problem effectively with min­ imal environmental impact. Nanotechnology and microfluidics have made enormous ad­ vances during the past decade in the area of biosensing and environmental remediation. The "marriage" of these two technologies can effectively address some of the above-mentioned needs [1]. In this dissertation, nanomaterials were used in conjunction with microfluidic techniques to detect and degrade biological and chemical pollutants. In the first project, a point-of-use sensor was developed for detection of trichloroethylene (TCE) from water. A self-organizing nanotubular titanium dioxide (TNA) synthesized by electrochemical anodization and functionalized with photocatalytically deposited platinum (Pt/TNA) was applied to the detection. The morphology and crystallinity of the Pt/TNA sensor was characterized using field emission scanning electron microscope, energy dis­ persive x-ray spectroscopy, and X-ray diffraction. The sensor could detect TCE in the concentrations ranging from 10 to 1000 ppm. The room-temperature operation capability of the sensor makes it less power intensive and can potentially be incorporated into a field-based sensor. In the second part, TNA synthesized on a foil was incorporated into a flow-based microfluidic format and applied to degradation of a model pollutant, methylene blue. The system was demonstrated to have enhanced photocatalytic performance at higher flow rates (50-200 ^L/min) over the same microfluidic format with TiO2 nanoparticulate (commercial P25) catalyst. The microfluidic format with TNA catalyst was able to achieve 82% fractional conversion of 18 mM methylene blue in comparison to 55% in the case of the TiO2 nanoparticulate layer at a flow rate of 200 L/min. The microfluidic device was fabricated using non-cleanroom-based methods, making it suitable for economical large-scale manufacture. A computational model of the microfluidic format was developed in COMSOL Multiphysics® finite element software to evaluate the effect of diffusion coefficient and rate constant on the photocatalytic performance. To further enhance the photocatalytic performance of the microfluidic device, TNA synthesized on a mesh was used as the catalyst. The new system was shown to have enhanced photocatalytic performance in comparison to TNA on a foil. The device was then employed in the inactivation of E. coli O157:H7 at different flow rates and light intensities (100, 50, 20, 10 mW/cm2). In the second project, a protocol for ultra-sensitive indirect electrochemical detection of E. coli O157:H7 was reported. The protocol uses antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized sec­ ondary (polystyrene) beads as an electrochemical tag. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL (S/N=3). We also demonstrate the use of the protocol for detection of E. coli O157:H7 seeded in wastewater effluent samples

Novel titania nanotube based electrochemical detection in micrototal analysis system

reportWe report the modification of titania (TiO2) nanotubes for quantitative electrochemical (EC) detection of biomolecules on a microfluidic platform

Advances in microfluidics and lab on a chip technologies

pre-printAdvances in molecular biology are enabling rapid and efficient analyses for effective intervention in domains like biology research, infectious disease management, food safety and bio-defense. The emergence of microfluidics and nanotechnologies has enabled both new capabilities and instrument sizes practical for point-of-care (POC). They have also introduced new functionality, enhanced the sensitivity, and reduced the time and cost involved in conventional molecular diagnostic techniques. This chapter reviews the application of microfluidics for molecular diagnostics methods like nucleic acid amplification, next generation sequencing, high resolution melting analysis, cytogenetics, protein detection and analysis, and cell sorting. We also review microfluidic sample preparation platforms applied to molecular diagnostics and targeted to sample-in, answer-out capabilities

Platinum functionalized titania nanotube array sensor for detection of Trichloroethylene in water

pre-printA sensor using platinum functionalized titania nanotubes for the detection of Trichloroethylene (TCE) in water samples has been developed. The titania nanotubes were synthesized using an electrochemical anodization technique and platinum was photocatalytically deposited on the nanotubes. The sensor exhibits a good response to TCE concentrations in the range of 10 to 1000 ppm

Synthesis of Rice Straw Fiber Reinforced Natural Rubber Composite and Effects of Surface Treatment in its Mechanical Properties

In the last decade the use of natural fiber in reinforcement of composite materials is increased, because of growing environmental awareness. The main objective of present work is to study the mechanical properties of rice straw fiber reinforced natural rubber composites at different weight fractions (20%, 30%, 40%, 50% and 60%) of rice straw fiber under treated and non treated conditions. At first the fiber is treated with NaOH, and then composite is manufactured for both untreated and treated fiber. After the synthesis of rice straw fiber reinforced natural rubber composite, The effects of surface treatment in its mechanical properties are studied. Rice straw fiber reinforced natural rubber composites were manufactured according to ASTM standards using compression molding technique. The developed composites were then tested for their mechanical properties, tensile, tear, density, abrasion, hardness, compression, and water absorption properties. The standard test methods used is, ASTM-D638M for tensile properties

MultiViz: A Gephi Plugin for Scalable Visualization of Multi-Layer Networks

The process of visually presenting networks is an effective way to understand entity relationships within the networks since it reveals the overall structure and topology of the network. Real networks are extremely difficult to visualize due to their immense complexity, which includes vast amounts of data, several types of interactions, various subsystems and several levels of connectivity as well as changes over time. This paper introduces the "MultiViz Plugin," a plugin for gephi, an open-source software tool for graph visualization and modification, in order to to visualize complex networks in a multi-layer manner. A collection of settings are availabe through the plugin to transform an existing network into a multi-layered network. The plugin supports several layout algorithms and lets user to choose which property of the network to be used as the layer. The goal of the study is to give the user complete control over how the network is visualized in a multi-layer fashion. We demonstrate the ability of the plugin to visualize multi-layer data using a real-life complex multi-layer datasets