scholarly journals Determining the Optimum Exposure and Recovery Periods for Efficient Operation of a QCM Based Elemental Mercury Vapor Sensor

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
K. M. Mohibul Kabir ◽  
Samuel J. Ippolito ◽  
Glenn I. Matthews ◽  
S. Bee Abd Hamid ◽  
Ylias M. Sabri ◽  
...  
Keyword(s):  
Quartz Substrate ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Anthropogenic Sources ◽  
Efficient Operation ◽  
Selective Layer ◽  
Low Concentrations ◽  
Recovery Times ◽  
Vapor Sensor ◽  
Mercury Sensors

In recent years, mass based transducers such as quartz crystal microbalance (QCM) have gained huge interest as potential sensors for online detection of elemental mercury (Hg0) vapor from anthropogenic sources due to their high portability and robust nature enabling them to withstand harsh industrial environments. In this study, we determined the optimal Hg0exposure and recovery times of a QCM based sensor for ensuring its efficient operation while monitoring low concentrations of Hg0vapor (<400 ppbv). The developed sensor was based on an AT-cut quartz substrate and utilized two gold (Au) films on either side of the substrate which functions as the electrodes and selective layer simultaneously. Given the temporal response mechanisms associated with mass based mercury sensors, the experiments involved the variation of Hg0vapor exposure periods while keeping the recovery time constant following each exposure and vice versa. The results indicated that an optimum exposure and recovery periods of 30 and 90 minutes, respectively, can be utilized to acquire the highest response magnitudes and recovery rate towards a certain concentration of Hg0vapor whilst keeping the time it takes to report an accurate reading by the sensor to a minimum level as required in real-world applications.

Cross sensitivity effects of volatile organic compounds on a SAW-based elemental mercury vapor sensor

2015 ◽  
Vol 212 ◽  
pp. 235-241 ◽  
Author(s):  
K.M. Mohibul Kabir ◽  
Ylias M. Sabri ◽  
Glenn I. Matthews ◽  
Samuel J. Ippolito ◽  
Suresh K. Bhargava
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Cross Sensitivity ◽  
Volatile Organic ◽  
Vapor Sensor ◽  
Elemental Mercury Vapor

Gold nanorods self-assembly on quartz crystal microbalance: An enhanced mercury vapor sensor

2021 ◽  
Author(s):  
Ylias Mohammad Sabri ◽  
Ahmad Kandjani ◽  
Christopher J Harrison ◽  
Satya Ranjan Sarker ◽  
anastasio chalkidis ◽  
...  
Keyword(s):  
Quartz Crystal Microbalance ◽  
Gold Nanorods ◽  
Self Assembly ◽  
Quartz Crystal ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Vapor Sorption ◽  
Vapor Sensor

A close-packed gold nanorods (Au-NR) monolayer was deposited on titanium-based quartz crystal microbalance (QCM) and its performance for elemental mercury (Hg0) vapor sorption and detection was compared with that of...

scholarly journals Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

2016 ◽  
Author(s):  
Xun Wang ◽  
Che-Jen Lin ◽  
Wei Yuan ◽  
Jonas Sommar ◽  
Wei Zhu ◽  
...  
Keyword(s):  
Forest Ecosystems ◽  
Agricultural Land ◽  
Mechanistic Model ◽  
Mainland China ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Model Verification ◽  
Surface Exchange ◽  
Field Shift ◽  
Elemental Mercury Vapor

Abstract. Mercury (Hg) emission from natural surfaces plays an important role in global Hg cycling. The present estimate of global natural emission has large uncertainty and remains unverified against field data, particularly for terrestrial surfaces. In this study, a mechanistic model is developed for estimating the emission of elemental mercury vapor (Hg0) from natural surfaces in China. The development implements recent advancements in the understanding of air-soil and air-foliage exchange of Hg0 and redox chemistry in soil and on surfaces, incorporates the effects of soil characteristics and landuse changes by agricultural activities, and is examined through a systematic set of sensitivity simulations. Using meteorology simulated by the Weather Research and Forecasting Model (WRF version 3.7), the exchange of Hg0 between the atmosphere and natural surfaces in Mainland China is estimated to be 465.1 Mg yr−1, including 565.5 Mg yr−1 of emission from soils, 9.0 Mg yr−1 of emission from water body, and 100.4 Mg yr−1 uptake by vegetation. The air-surface exchange is strongly dependent on the landuse and meteorology, with 9 % of net emission from forest ecosystems, 50 % from shrubland, and savanna and grassland, 33 % from cropland, and 8 % from other landuses. Given the large agricultural land area in China, farming activities play an important role on the air-surface exchange in farmland. Particularly, rice field shift from a net sink (3.3 Mg uptake) during April to October (rice planting) to a net source when the farmland is not flooded (November-March). Summing up emissions from each landuse, more than half of the total emission occurs in summer (51 %), followed by spring (28 %), autumn (13 %) and winter (8 %). Model verification is accomplished using observational data of air-soil/air-water fluxes and Hg deposition through litterfall for forest ecosystems in China and Monte Carlo simulations. In contrast to the earlier estimate by Shetty et al. (2008) that reported large emission from vegetative surfaces using an evapotranspiration approach, the estimate in this study shows natural emissions are primarily from grassland and dry cropland. Such an emission pattern may alter the current understanding of Hg emission outflow from China as reported by Lin et al. (2010b) because of a substantial natural Hg emission occurs in West China.

Stable Isotope Evidence Shows Re-emission of Elemental Mercury Vapor Occurring after Reductive Loss from Foliage

2018 ◽  
Vol 53 (2) ◽  
pp. 651-660 ◽  
Author(s):  
Wei Yuan ◽  
Jonas Sommar ◽  
Che-Jen Lin ◽  
Xun Wang ◽  
Kai Li ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Isotope Evidence ◽  
Elemental Mercury Vapor

scholarly journals SnO2/TiO2 Thin Film n-n Heterostructures of Improved Sensitivity to NO2

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6830
Author(s):  
Piotr Nowak ◽  
Wojciech Maziarz ◽  
Artur Rydosz ◽  
Kazimierz Kowalski ◽  
Magdalena Ziąbka ◽  
...  
Keyword(s):  
Thin Film ◽  
Operating Temperature ◽  
Incidence Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Response Recovery ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
Recovery Times

Thin-film n-n nanoheterostructures of SnO2/TiO2, highly sensitive to NO2, were obtained in a two-step process: (i) magnetron sputtering, MS followed by (ii) Langmuir-Blodgett, L–B, technique. Thick (200 nm) SnO2 base layers were deposited by MS and subsequently overcoated with a thin and discontinuous TiO2 film by means of L–B. Rutile nanopowder spread over the ethanol/chloroform/water formed a suspension, which was used as a source in L–B method. The morphology, crystallographic and electronic properties of the prepared sensors were studied by scanning electron microscopy, SEM, X-ray diffraction, XRD in glancing incidence geometry, GID, X-ray photoemission spectroscopy, XPS, and uv-vis-nir spectrophotometry, respectively. It was found that amorphous SnO2 films responded to relatively low concentrations of NO2 of about 200 ppb. A change of more than two orders of magnitude in the electrical resistivity upon exposure to NO2 was further enhanced in SnO2/TiO2 n-n nanoheterostructures. The best sensor responses RNO2/R0 were obtained at the lowest operating temperatures of about 120 °C, which is typical for nanomaterials. Response (recovery) times to 400 ppb NO2 were determined as a function of the operating temperature and indicated a significant decrease from 62 (42) s at 123 °C to 12 (19) s at 385 °C A much smaller sensitivity to H2 was observed, which might be advantageous for selective detection of nitrogen oxides. The influence of humidity on the NO2 response was demonstrated to be significantly below 150 °C and systematically decreased upon increase in the operating temperature up to 400 °C.

Effect of occupational exposure to elemental mercury in the amalgam on thymulin hormone production among dental staff

2009 ◽  
Vol 25 (3) ◽  
pp. 159-167 ◽  
Author(s):  
SA Farahat ◽  
LA Rashed ◽  
NH Zawilla ◽  
SM Farouk
Keyword(s):  
Nitric Oxide ◽  
Occupational Exposure ◽  
Blood Level ◽  
Body Burden ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Dental Amalgam ◽  
Thymus Gland ◽  
Hygiene Measures ◽  
Dental Staff

Occupational exposure of dental staff to elemental mercury vapor released from dental amalgam is an issue of concern because of the possible immunological and neurological adverse outcomes. Recently, studies have reported that inorganic mercury induces immunosuppression by decreasing the production of thymus gland hormone (thymulin). This study aimed at investigating mercury body burden in dental staff and the relation of this burden to the potential impact of mercury on thymus gland hormone level (thymulin). Besides, the work aimed at verifying mercury effect on nitric oxide synthetase as a possible mechanism of its immunotoxicity. The study population consisted of a group of dental staff ( n = 39) [21 dentists and 18 nurses] and a matched control group ( n = 42). Each individual was subjected to detailed occupational and medical history taking and to estimation of urinary mercury (U-Hg) and blood mercury (B-Hg) as indicators of mercury body burden and exposure, respectively. Measurement of total thymulin hormone blood level, and plasma level of nitrite and nitrate (indicators of nitric oxide) was also done. The study showed a significantly increased U-Hg and B-Hg levels in the dental staff compared to their controls. This elevation of mercury body burden was associated with significant reduction in thymulin hormone blood level and nitric oxide parameters. These results were more evident in the group of nurses compared to the dentists. In conclusion, our results show that dentists and dental nurses have significant exposure to mercury vapor and point to the negative impact of mercury on thymus gland functions and confirm the implication that the nitric oxide pathway is a possible mechanism for this impact. Moreover, the study raises attention to the importance of hygiene measures in reduction of exposure to mercury vapor released from dental amalgam.

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