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Open Access. Powered by Scholars. Published by Universities.®

2019

Civil and Environmental Engineering

University of Nebraska - Lincoln

Keyword
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Articles 121 - 123 of 123

Full-Text Articles in Engineering

Time-Domain And Frequency-Domain Reflectometry Type Soil Moisture Sensor Performance And Soil Temperature Effects In Fine- And Coarse-Textured Soils, Y. Zhu, S. Irmak, A. J. Jhala, M. C. Vuran, A. Diotto Jan 2019

Time-Domain And Frequency-Domain Reflectometry Type Soil Moisture Sensor Performance And Soil Temperature Effects In Fine- And Coarse-Textured Soils, Y. Zhu, S. Irmak, A. J. Jhala, M. C. Vuran, A. Diotto

Biological Systems Engineering: Papers and Publications

The performances of six time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR) type soil moisture sensors were investigated for measuring volumetric soil-water content (θv) in two different soil types. Soil-specific calibration equations were developed for each sensor using calibrated neutron probe-measured θv. Sensors were also investigated for their performance response in measuring θv to changes in soil temperature. The performance of all sensors was significantly different (P<0.05) than the neutron probe-measured θv, with the same sensor also exhibiting variation between soils. In the silt loam soil, the 5TE sensor had the lowest root mean squared error (RMSE) of 0.041 …


Optimization Of Process Parameters And Fermentation Strategy For Xylanase Production In A Stirred Tank Reactor Using A Mutant Aspergillus Nidulans Strain, Asmaa Abdella, Fernando Segato, Mark R. Wilkins Jan 2019

Optimization Of Process Parameters And Fermentation Strategy For Xylanase Production In A Stirred Tank Reactor Using A Mutant Aspergillus Nidulans Strain, Asmaa Abdella, Fernando Segato, Mark R. Wilkins

Biological Systems Engineering: Papers and Publications

The present work studied the optimization of aeration rate, agitation rate and oxygen transfer and the use of various batch fermentation strategies for xylanase production from a recombinant Aspergillus nidulans strain in a 3 L stirred tank reactor. Maximum xylanase production of 1250 U/mL with productivity of 313 U/mL/day was obtained under an aeration rate of 2 vvm and an agitation rate of 400 rpm using batch fermentation. The optimum volumetric oxygen transfer coefficient (kLa) for efficient xylanase production was found to be 38.6 h1. Fed batch mode and repeated batch fermentation was also performed with kLa was 38.6 h1. …


Antibiotic Resistance Gene Profile Changes In Cropland Soil After Manure Application And Rainfall, Morgan Meyers, Lisa Durso, John E. Gilley, Heidi Waldrip, Lana Castleberry, Amy Millmier Schmidt Jan 2019

Antibiotic Resistance Gene Profile Changes In Cropland Soil After Manure Application And Rainfall, Morgan Meyers, Lisa Durso, John E. Gilley, Heidi Waldrip, Lana Castleberry, Amy Millmier Schmidt

Biological Systems Engineering: Papers and Publications

Land application of manure introduces gastrointestinal microbes into the environment, including bacteria carrying antibiotic resistance genes (ARGs). Measuring soil ARGs is important for active stewardship efforts to minimize gene flow from agricultural production systems; however, the variety of sampling protocols and target genes makes it difficult to compare ARG results between studies. We used polymerase chain reaction (PCR) methods to characterize and/or quantify 27 ARG targets in soils from 20 replicate, long-term no-till plots, before and after swine manure application and simulated rainfall and runoff. All samples were negative for the 10 b-lactamase genes assayed. For tetracycline resistance, only source …