Quaternary ammonium compounds(QACs)are a class of antimicrobial disinfectants whose use in cleaning products increased during the COVID-19 pandemic.Chemically,their low vapor pressure indicates a proclivity to persist...Quaternary ammonium compounds(QACs)are a class of antimicrobial disinfectants whose use in cleaning products increased during the COVID-19 pandemic.Chemically,their low vapor pressure indicates a proclivity to persist on surfaces,and their presence suggests a level of protection against microorganisms.The widespread application of QACs in response to the SARS CoV-2 virus created a need to evaluate their longevity on surfaces,for both efficacy and possible health risks.There are however,no standardized analytical methods for QAC surface sampling and analysis,and no published studies quantifying their concentrations on mass transportation vehicles-a high occupancy,close-contact microenvironment documented to facilitate the spread the SARS CoV-2 virus.Here,we describe a robust liquid chromatography mass spectrometry(LC-MS)method for the analysis of QACs and simultaneous development of a direct surface sampling and extraction protocol.We demonstrate the applicability of the method through the analysis of surface samples collected from in-service public transportation buses.The rapid,sensitive LC-MS method included 8 target QACs quantified on a Q-Exactive HF Hybrid Quadrupole-Orbitrap mass spectrometer using an electrospray ionization source and Dionex UltiMate 3000 UHPLC system for analyte separation.QAC standard mixtures at concentrations between 0.1 ng mL^(-1)and 2000 ng mL^(-1)were analyzed,and chromatographic separation of all analytes was achieved in less than 10 min.All correlation coefficients were reported at r>0.986,and LODs ranged from 0.007 to 2.103 ng mL^(-1)for all compounds,confirming the method's sensitivity.A previously reported surface sampling and extraction protocol was modified to further simplify the procedure and expand the number of target compounds.The new sampling protocol was optimized from 10 commercially available wipes and 4 solvent types by quantifying recovery from the surface.Band-Aid brand small gauze pads saturated with isopropanol had the highest recovery efficiencies,ranging from 61.5 to 102.9%across all analytes.To test the real-world applicability,wipe samples were collected from 4 in-circulation New Jersey Transit buses on 5 separate days over the course of a month to assess the occurrence and longevity of QACs on sanitized mass transportation vehicles.Concentrations of QACs were detected on every wipe sample taken,and at all sampled time points,confirming their persistence on hard surfaces.QACs have the potential to form polymers,and detection of the polymer might serve as a secondary indication of their effectiveness on surfaces.None of the polymers detected however,were unique to QACs from this study.The polymers detected were already present in the wipe and used as an internal standard to demonstrate the efficacy of extraction and analysis of polymeric QACs.展开更多
Containerized shipping is a growing market for agricultural exports,particularly soybeans.In order to understand the optimal strategies for improving the United States’economic competitiveness in this emerging market...Containerized shipping is a growing market for agricultural exports,particularly soybeans.In order to understand the optimal strategies for improving the United States’economic competitiveness in this emerging market,this research develops an intermodal transportation network modeling framework,focusing on U.S.soybean container shipments.Built upon detailed modal cost analyses,a Geospatial Intermodal Freight Transportation(GIFT)model has been developed to understand the optimal network design for U.S.soybean exports.Based on market demand and domestic supply figures,the model is able to determine which domestically produced soybeans should go to which foreign markets,and by which transport modes.This research and its continual studies,will provide insights into future policies and practices that can improve the transportation efficiency of soybean logistics.展开更多
Based on past studies, exit ramp terminals are the common locations for drivers to enter a physically separated highway in the wrong direction. Currently, many drivers, especially nonlocal drivers, often rely on voice...Based on past studies, exit ramp terminals are the common locations for drivers to enter a physically separated highway in the wrong direction. Currently, many drivers, especially nonlocal drivers, often rely on voice-guided navigation apps and Global Positioning System (GPS) devices to navigate their routes on and off freeways. A few studies have reported that GPS devices sometimes give drivers wrong information and cause wrong-way entry into a freeway, especially at some confusing interchanges, such as partial cloverleaf and compressed diamond interchanges. The access points located close to exit ramps may also cause a problem for GPS devices in sending accurate voice-guidance. It is unknown if current GPS devices are capable of properly informing drivers regarding turning movements in advance of exit ramp terminals at some common interchanges. The objective of this study is to evaluate the most commonly used GPS devices/navigation apps to identify existing problems and their potential for reducing wrong-way driving (WWD) incidents at interchange terminals. Field experiments were conducted at 10 common freeway interchanges or interchanges with nearby access driveways in the state of Alabama. Results show that most GPS devices have difficulty in providing correct guidance when the spacing between an access point and an exit ramp is less than 300 feet. Our comparison of five different GPS devices used on the same routes reveals that navigation apps have more limitations in guiding drivers than stand-alone GPS devices. Recommendations are offered to help GPS mapping companies improve their devices or add new features to reduce the occurrence of WWD.展开更多
基金the support of the Center for Environmental Exposures and Disease(CEED)NIH-NIEHS Grant nos.P30 ES005022 and T32 ES019854This research was supported in part by Grant no.69A3551847102 from the U.S.Department of Transportation,Office of the Assistant Secretary for Research and Technology(OST-R).
文摘Quaternary ammonium compounds(QACs)are a class of antimicrobial disinfectants whose use in cleaning products increased during the COVID-19 pandemic.Chemically,their low vapor pressure indicates a proclivity to persist on surfaces,and their presence suggests a level of protection against microorganisms.The widespread application of QACs in response to the SARS CoV-2 virus created a need to evaluate their longevity on surfaces,for both efficacy and possible health risks.There are however,no standardized analytical methods for QAC surface sampling and analysis,and no published studies quantifying their concentrations on mass transportation vehicles-a high occupancy,close-contact microenvironment documented to facilitate the spread the SARS CoV-2 virus.Here,we describe a robust liquid chromatography mass spectrometry(LC-MS)method for the analysis of QACs and simultaneous development of a direct surface sampling and extraction protocol.We demonstrate the applicability of the method through the analysis of surface samples collected from in-service public transportation buses.The rapid,sensitive LC-MS method included 8 target QACs quantified on a Q-Exactive HF Hybrid Quadrupole-Orbitrap mass spectrometer using an electrospray ionization source and Dionex UltiMate 3000 UHPLC system for analyte separation.QAC standard mixtures at concentrations between 0.1 ng mL^(-1)and 2000 ng mL^(-1)were analyzed,and chromatographic separation of all analytes was achieved in less than 10 min.All correlation coefficients were reported at r>0.986,and LODs ranged from 0.007 to 2.103 ng mL^(-1)for all compounds,confirming the method's sensitivity.A previously reported surface sampling and extraction protocol was modified to further simplify the procedure and expand the number of target compounds.The new sampling protocol was optimized from 10 commercially available wipes and 4 solvent types by quantifying recovery from the surface.Band-Aid brand small gauze pads saturated with isopropanol had the highest recovery efficiencies,ranging from 61.5 to 102.9%across all analytes.To test the real-world applicability,wipe samples were collected from 4 in-circulation New Jersey Transit buses on 5 separate days over the course of a month to assess the occurrence and longevity of QACs on sanitized mass transportation vehicles.Concentrations of QACs were detected on every wipe sample taken,and at all sampled time points,confirming their persistence on hard surfaces.QACs have the potential to form polymers,and detection of the polymer might serve as a secondary indication of their effectiveness on surfaces.None of the polymers detected however,were unique to QACs from this study.The polymers detected were already present in the wipe and used as an internal standard to demonstrate the efficacy of extraction and analysis of polymeric QACs.
基金The first author was funded by the Department of Civil and Environmental Engineering(CEE)at Rutgers UniversityThe second author was funded by the US Department of Agri-culture(15-TMXXX-NJ-0008)+1 种基金The third author was funded by National Natural Science Foundation of China(Grant No.51409157)Program of Humanities and Social Science of the Ministry of Education of China(14YJC630008).
文摘Containerized shipping is a growing market for agricultural exports,particularly soybeans.In order to understand the optimal strategies for improving the United States’economic competitiveness in this emerging market,this research develops an intermodal transportation network modeling framework,focusing on U.S.soybean container shipments.Built upon detailed modal cost analyses,a Geospatial Intermodal Freight Transportation(GIFT)model has been developed to understand the optimal network design for U.S.soybean exports.Based on market demand and domestic supply figures,the model is able to determine which domestically produced soybeans should go to which foreign markets,and by which transport modes.This research and its continual studies,will provide insights into future policies and practices that can improve the transportation efficiency of soybean logistics.
文摘Based on past studies, exit ramp terminals are the common locations for drivers to enter a physically separated highway in the wrong direction. Currently, many drivers, especially nonlocal drivers, often rely on voice-guided navigation apps and Global Positioning System (GPS) devices to navigate their routes on and off freeways. A few studies have reported that GPS devices sometimes give drivers wrong information and cause wrong-way entry into a freeway, especially at some confusing interchanges, such as partial cloverleaf and compressed diamond interchanges. The access points located close to exit ramps may also cause a problem for GPS devices in sending accurate voice-guidance. It is unknown if current GPS devices are capable of properly informing drivers regarding turning movements in advance of exit ramp terminals at some common interchanges. The objective of this study is to evaluate the most commonly used GPS devices/navigation apps to identify existing problems and their potential for reducing wrong-way driving (WWD) incidents at interchange terminals. Field experiments were conducted at 10 common freeway interchanges or interchanges with nearby access driveways in the state of Alabama. Results show that most GPS devices have difficulty in providing correct guidance when the spacing between an access point and an exit ramp is less than 300 feet. Our comparison of five different GPS devices used on the same routes reveals that navigation apps have more limitations in guiding drivers than stand-alone GPS devices. Recommendations are offered to help GPS mapping companies improve their devices or add new features to reduce the occurrence of WWD.