No description available.

With a growing concern for the environment and increasing urbanization of rural areas, understanding the characteristics of urban non-point source pollution has become a focus for water quality investigators. Once thought to be a small contributor to the pollution problem, urban non-point sources are now responsible for transporting over 50% of all pollutants into natural waterways. Assessing non-point source pollution is the key to future water quality improvements in natural receiving waters. The purpose of this research was to investigate the water quality of an urbanized watershed, analyze current prediction methods and to investigate the effectiveness of an extended dry detention basin as a pollutant removal management practice on a 21.68-acre urban watershed on the Virginia Tech Campus. This research included extensive stormwater monitoring and sampling to characterize the runoff and water quality from an urban watershed. The resulting analysis included comparing well-known desktop prediction methods with pollutant removal rates using an extended dry detention basin and comparison with different literature values. Finally, the study team calibrated the PSRM-QUAL model for watershed prediction of non-point source runoff and pollution. The results of the stormwater monitoring process show that water quality prediction methods are not very successful on a storm by storm basis, but can be fairly accurate over longer periods of time with little or no storm water quality sampling. The extended dry detention basin is a simple yet effective management practice for the removal of sediments and sediment bound pollutants. / Master of Science

Fresh tannic acid (5%) (FTA), heated to 121C for 15 min (PTA), and the combination of FTA and phosphates (FPH) were vacuum tumbled with catfish fillets and compared to water tumbled fillets (CTL). Fillets treated with FTA or PTA had higher whiteness whereas all treated fillets had higher chroma values than CTL, resulting in a deeper yellow color fillet. Microbial shelf life (CTL, log CFU/g, APC) of FTA and PTA treated fillets was extended by two days, to11.8 d at 4C, but FPH fillets did not reach over 5 log CFU/g for 15 d of storage. Fat from FTA and PTA treated fillets had induction points (IP) of 4.0 and 3.4 h, respectively, whereas FPH and CTL samples had IP of 1.4 and 2.4 h. Thus, FPH seems to be the best antimicrobial treatment and FTA/PTA, the best antioxidant treatment.

Early detection is crucial in delivering timely treatment and improving patient outcomes. Point-of-care (POC) biosensors play an essential role in early detection, allowing for rapid and accurate diagnosis of diseases at the patient’s bedside without the need for expensive equipment or specialized personnel. By performing the analysis on-site, POC diagnostics can offer continuous monitoring and real-time data acquisition of a patient's health status. Thus, there is strong incentive in creating POC biosensors to provide healthcare professionals with greater access to diagnostic information, ultimately improving outcomes and reducing healthcare costs. Herein, the development of a POC lab-in-a-tube biosensor that utilizes simple and scalable fabrication techniques is presented. Electrodes are patterned on low-cost plastic substrates, which can be subsequently rolled and heat-shrunk into miniaturized tubing for flow-through analysis of liquid samples. Heat-shrinking of the device results in 3-dimensional, hierarchically wrinkled electrodes with morphological feature that span several orders of magnitude in size. These wrinkled electrodes demonstrate dramatically increased surface area in a given footprint compared to traditional planar electrodes. Incorporation of modified gold and silver wires allows for sensitive and stable electrochemical detection, enabling fast and quantitative results. These devices are capable of millilitre-per-minute flow rates to allow for rapid sample processing and for increased mass-transport to the electrode surface. The ability to capture analytes was characterized with nucleic acid sequences using pump-driven and blood-collection tube induced flow for rapid and accurate detection. Overall, this work demonstrates the successful development of an electrochemical platform integrated into a plastic tubing capable of rapid detection of flowing analytes. With its ease-of-use and compatibility with a wide range of flow rates, the device has the potential to be incorporated with existing medical tubing and procedures to achieve POC diagnostics. / Thesis / Master of Applied Science (MASc) / Early detection is critical for timely treatment and better patient outcomes. Point-of-care (POC) biosensors allow for disease diagnosis and real-time monitoring of a patient's health status directly at the patient's bedside without the need for expensive equipment or specialized personnel. A lab-in-a-tube biosensor was developed using sensing surfaces on low-cost plastic that is rolled and heat-shrunk into miniaturized tubing for analysis of liquid samples. The wrinkled sensing surface that results from heat-shrinking dramatically increase surface area and interaction with the sample, enabling sensitive detection that is fast and quantitative. These devices are capable of capturing samples at high flow rates, allowing for rapid analysis of large samples. Overall, this work demonstrates the successful creation of a biosensor platform that could be incorporated with existing medical tubing for POC diagnostics.

Researchers and GIS analysts have used Aerial Laser Scanning (ALS) data to generate Digital Terrain Models (DTM) since the 1990s, and various algorithms developed for ground point extraction have been proposed based on the characteristics of ALS data. However, Terrestrial Laser Scanning (TLS) data, which might be a better indicator of ground morphological features under dense tree canopies and more accessible for small areas, have been long ignored. In this research, the aim was to evaluate if TLS data were as qualified as ALS to serve as a source of a DTM. To achieve this goal, there were three steps: acquiring and aligning ALS and TLS of the same region, applying ground filters on both of the data sets, and comparing the results. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble's Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a DTM generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid. / Master of Science / Elevation is one of the most basic data for researches such as flood prediction and land planning in the field of geography, agriculture, forestry, etc. The most common elevation data that could be downloaded from the internet were acquired from field measurements or satellites. However, the finest grained of that kind of data is 1/3m and errors can be introduced by ground objects such as trees and buildings. To acquire more accurate and pure-ground elevation data (also called Digital Terrain Models (DTM)), Researchers and GIS analysts introduced laser scanners for small area geographical research. For land surface data collection, researchers usually fly a drone with laser scanner (ALS) to derive the data underneath, which could be blocked by ground objects. An alternative way is to place the laser scanner on a tripod on the ground (TLS), which provides more data for ground morphological features under dense tree canopies and better precision. As ALS and TLS collect data from different perspectives, the coverage of a ground area can be different. As most of the ground extraction algorithm were designed for ALS data, their performance on TLS data hasn’t been fully tested yet. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble’s Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a ground surface generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid.

Abstract Not Provided. / Thesis / Master of Science (MSc)

Abstract Not Provided. / Thesis / Master of Science (MSc)

No description available.

No description available.

According to the third international consensus definition (sepsis-3), sepsis is characterized as life-threatening organ dysfunction resulting from an uncontrolled host response to infection. Sepsis stands as a prominent contributor to worldwide mortality. A study revealed approximately 50 million reported cases of sepsis and 11 million associated deaths worldwide, constituting nearly 20% of all global fatalities. Various biomarkers have been investigated for sepsis prognosis including Procalcitonin (PCT), C-reactive protein (CRP), interleukin-1β (IL-1β), interleukin-6 (IL-6), and protein C. In addition to proteomic markers genomic biomarkers have also been investigated for sepsis. For instance, research indicates a substantial rise in plasma cell-free DNA (cfDNA) and total circulating histones levels during sepsis, correlating with its severity and mortality. The complexity arises in creating a measurement tool for sepsis, given the diverse nature of these biomarkers, each requiring distinct detection methods. The objective of this doctoral thesis is to develop a low-cost fully integrated microfluidic device for detecting a genomic biomarker (cfDNA) and a proteomic biomarker (total circulating histones) using a new method for integration of hydrogels inside microfluidic devices during the fabrication process. This method involves using porous and fibrous membranes as scaffolds to support gels. The scaffold facilitates the drying and reconstitution of these gels without any loss of shape or leakage, making it advantageous in various applications, especially in point-of-care (POC) devices where long-term storage of gels inside the device is required. This hydrogel integration method was applied to demonstrate gel electrophoretic concentration and isoelectric trapping of cfDNA and histones respectively in rehydrated agarose gates with proper pH embedded in a porous membrane in a microfluidic device. Then, these two detections were performed in a single fully integrated microfluidic device. Additionally, nonspecific fluorescent dyes were incorporated within the device, eliminating the necessity for off-chip sample preparation. This enables direct testing of plasma samples without the need to label DNA and histones with fluorescent dyes beforehand. In all the fabrication steps of the microfluidic device, xurography, a cost-effective and rapid fabrication method, was utilized. This device demonstrated the effective separation of cfDNA and histones in the agarose gates in a total time of 20 minutes, employing 10 and 30 Volts for cfDNA and histone accumulation, respectively. This device could be further developed to create a POC device for the quantification of cfDNA and histones simultaneously in severe sepsis patients plasma sample. / Thesis / Doctor of Philosophy (PhD)