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A surface sampling and liquid chromatography mass spectrometry method for the analysis of quaternary ammonium compounds collected from public transportation buses in New Jersey
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作者 Abigail Lazofsky Cathleen Doherty +1 位作者 Patrick Szary Brian Buckley 《Emerging Contaminants》 2022年第1期318-328,共11页
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
关键词 Alkyl dimethyl benzyl ammonium chloride Alkyl(ethyl benzyl)dimethyl ammonium chloride Surface sampling Orbitrap mass spectrometry Public transportation COVID-19
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An intermodal transportation geospatial network modeling for containerized soybean shipping 被引量:2
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作者 Xiang Liu Yun Bai Jihong Chen 《Journal of Ocean Engineering and Science》 SCIE 2017年第2期143-153,共11页
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
关键词 International shipping RAIL TRUCK BARGE Agricultural logistics Intermodal
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Evaluation of navigation performances of GPS devices near interchange area pertaining to wrong-way driving
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作者 Mohammad Jalayer Huaguo Zhou Beijia Zhang 《Journal of Traffic and Transportation Engineering(English Edition)》 2016年第6期593-601,共9页
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
关键词 Wrong-way driving Exit ramp Interchange GPS device Navigation app
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