scholarly journals Hydrostatic Densitometer for Monitoring Density in Freshwater to Hypersaline Water Bodies

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1842
Author(s):  
Ziv Mor ◽  
Hallel Lutzky ◽  
Eyal Shalev ◽  
Nadav G. Lensky
Keyword(s):  
Continuous Monitoring ◽  
Pressure Sensors ◽  
Temporal Variations ◽  
Dead Sea ◽  
Conductivity Measurements ◽  
Lake Levels ◽  
Density Profiles ◽  
Water Column Stratification ◽  
Hypersaline Water ◽  
First Time

Density, temperature, salinity, and hydraulic head are physical scalars governing the dynamics of aquatic systems. In coastal aquifers, lakes, and oceans, salinity is measured with conductivity sensors, temperature is measured with thermistors, and density is calculated. However, in hypersaline brines, the salinity (and density) cannot be determined by conductivity measurements due to its high ionic strength. Here, we resolve density measurements using a hydrostatic densitometer as a function of an array of pressure sensors and hydrostatic relations. This system was tested in the laboratory and was applied in the Dead Sea and adjacent aquifer. In the field, we measured temporal variations of vertical profiles of density and temperature in two cases, where water density varied vertically from 1.0 × 103 kg·m−3 to 1.24 × 103 kg·m−3: (i) a borehole in the coastal aquifer, and (ii) an offshore buoy in a region with a diluted plume. The density profile in the borehole evolved with time, responding to the lowering of groundwater and lake levels; that in the lake demonstrated the dynamics of water-column stratification under the influence of freshwater discharge and atmospheric forcing. This method allowed, for the first time, continuous monitoring of density profiles in hypersaline bodies, and it captured the dynamics of density and temperature stratification.

scholarly journals Spaceborne GNSS-R Observation of Global Lake Level: First Results from the TechDemoSat-1 Mission

2019 ◽  
Vol 11 (12) ◽  
pp. 1438 ◽  
Author(s):  
Liwen Xu ◽  
Wei Wan ◽  
Xiuwan Chen ◽  
Siyu Zhu ◽  
Baojian Liu ◽  
...  
Keyword(s):  
Satellite System ◽  
Temporal Variations ◽  
Strong Correlations ◽  
Lake Levels ◽  
The Caspian Sea ◽  
First Results ◽  
The Uk ◽  
Global Navigation Satellite ◽  
Inland Water Bodies ◽  
First Time

Spaceborne global navigation satellite system reflectometry (GNSS-R) data collected by the UK TechDemoSat-1 (TDS-1) satellite is applied to retrieve global lake levels for the first time. Lake levels of 351 global lakes (area greater than 500 km2 and elevation lower than 3000 m each) are estimated using TDS-1 Level 1b data over 2015–2017. Strong correlations (overall R2 greater than 0.95) are observed among lake levels derived from TDS-1 and other altimetry satellites such as CryoSat-2, Jason, and Envisat (the latter two are collected by Hydroweb), although with large root-mean-square error (RMSE) (tens of meters) mainly due to the fact that TDS-1 is not dedicated for altimetry measuring purpose. Examples of the Caspian Sea and the Poyang Lake show consistent spatial and temporal variations between TDS-1 and other data sources. The results in this paper provide supportive information for further application of GNSS-R constellations to measure altimetry of inland water bodies.

Enhanced piezocapacitive response in zinc oxide tetrapod–poly(dimethylsiloxane) composite dielectric layer for flexible and ultrasensitive pressure sensor

Nanoscale ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 6076-6086
Author(s):  
Gen-Wen Hsieh ◽  
Shih-Rong Ling ◽  
Fan-Ting Hung ◽  
Pei-Hsiu Kao ◽  
Jian-Bin Liu
Keyword(s):  
Zinc Oxide ◽  
Pressure Sensor ◽  
Dielectric Layer ◽  
Pressure Sensors ◽  
Dielectric Matrix ◽  
First Time

Zinc oxide tetrapod is introduced for the first time within a poly(dimethylsiloxane) dielectric matrix for the formation of ultrasensitive piezocapacitive pressure sensors.

Stromatolites in caves of the Dead Sea Fault Escarpment: implications to latest Pleistocene lake levels and tectonic subsidence

2009 ◽  
Vol 28 (1-2) ◽  
pp. 80-92 ◽  
Author(s):  
Sorin Lisker ◽  
Anton Vaks ◽  
Miryam Bar-Matthews ◽  
Roi Porat ◽  
Amos Frumkin
Keyword(s):  
Dead Sea ◽  
Tectonic Subsidence ◽  
Lake Levels ◽  
The Dead

scholarly journals Impact of VOCs on the formation of ozone in a central China city during severe pollution periods

2018 ◽  
Author(s):  
Bowei Li ◽  
Steven Sai Hang Ho ◽  
Sunling Gong ◽  
Jingwei Ni ◽  
Huairui Li ◽  
...  
Keyword(s):  
Temporal Variations ◽  
Central China ◽  
Compressed Natural Gas ◽  
Pmf Model ◽  
Sampling Campaign ◽  
Time Period ◽  
Ozone Formation Potential ◽  
Range Transport ◽  
Volatile Organic ◽  
First Time

Abstract. In this work, a five-month sampling campaign was conducted for volatile organic compounds (VOCs) for the first time in Zhengzhou City, Henan province, China, where ozone (O3) pollution has shown an increasing trend in recent years. Fifty-seven VOCs defined by the Photochemical Assessment Monitoring Stations (PAMS) were sampled using canister method. Meanwhile, other O3 precursor gases were monitored online at four different sites between the time period of May–September, 2017. The results indicated that the average mixing ratio of ΣPAMS (31.57 ± 23.35 ppbv) in Zhengzhou was lower than the other megacities in China, while alkyne was in a significantly higher proportion. The abundances, compositions and ratios of PAMS showed strong spatial and temporal variations. Alkenes were the largest contributors to the ozone formation potential (OFP). On clear days, higher O3 levels were often accompanied with high ΣPAMS/NOx ratio at each site, demonstrating that the VOCs were more sensitive during the O3 formation period in Zhengzhou. Furthermore, source apportionmemt was conducted with Positive Matrix Factorization (PMF) model, and it was found that the use of compressed natural gas (CNG), the evaporation of gasoline and the exhaust from vehicles were the important sources for ambient VOCs at all four sites. Besides, the meterological conditions and long-range transport from other surrounding provinces also had an impact on the air quality determined using the cluster analysis. It is worth mentioning that the reduction in VOCs' emissions is necessary to suppress the O3 pollution.

scholarly journals The Susceptibility of Meningococci to the Antimicrobial Agents in Moscow 2006 - 2015

2016 ◽  
Vol 15 (3) ◽  
pp. 7-14 ◽  
Author(s):  
M. A. Koroleva ◽  
I. S. Koroleva ◽  
I. M. Zakroeva ◽  
I. M. Gruber
Keyword(s):  
Cerebrospinal Fluid ◽  
Continuous Monitoring ◽  
Antimicrobial Agents ◽  
Meningococcal Infection ◽  
Test Results ◽  
Prognostic Criteria ◽  
Comparison Results ◽  
Moderately Resistant ◽  
First Time

Relevance. One of the prognostic criteria meningococcal infection (MI) epidemic status process is the increasing number of resistant to antibiotics meningococcal strains. Aim of this study was to investigate the dynamics of invasive strains of N. meningitidis susceptibility to antibiotics in Moscow in 2006 - 2015. Materials and methods. Studied 98 strains of N. meningitidis, isolated from blood and cerebrospinal fluid of patients with MI. The study changes of sensitivity N. meningitidis to antibiotics was occured in two periods: first -2006 - 2011 and second - 2012 - 2015. The MIC was determined by E-test. Results. In the present study revealed for the first time the Russian strains of N. meningitidis, moderately resistant to penicillin (5 strains) and resistant to rifampicin (3 strains). Among the studied strains were not found resistant to ceftriaxone, ciprofloxacin, tetracycline and chloramphenicol. Discussion. Comparison results two study periods allowed to reveal the dynamics of increasing the sensitivity of N. meningitidis to antibiotics, which confirms the decline in meningococcal virulence, and as a result, continued interepidemic MI period. Conclusions. Despite the decline antibakterial resistance is required continuous monitoring.

scholarly journals Spatial and temporal variations of CO<sub>2</sub> mole fractions observed at Beijing, Xianghe and Xinglong in North China

2021 ◽  
Author(s):  
Yang Yang ◽  
Minqiang Zhou ◽  
Ting Wang ◽  
Bo Yao ◽  
Pengfei Han ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Human Activities ◽  
North China ◽  
Terrestrial Ecosystem ◽  
Temporal Variations ◽  
Spatial And Temporal Variations ◽  
Boundary Layer Height ◽  
The Mean ◽  
The Impact ◽  
First Time

Abstract. Atmospheric CO2 mole fractions are observed at Beijing (BJ), Xianghe (XH), and Xinglong (XL) in North China using the Picarro G2301 Cavity Ring-Down Spectroscopy instruments. The measurement system is described comprehensively for the first time. The geo-distances among these three sites are within 200 km, but they have very different surrounding environments: BJ is inside the megacity; XH is in the suburban area; XL is in the countryside on a mountain. The mean and standard deviation of CO2 mole fractions at BJ, XH, and XL between October 2018 and September 2019 are 448.4 ± 12.8 ppm, 436.0 ± 9.2 ppm and 420.6 ± 8.2 ppm, respectively. The seasonal variations of CO2 at these three sites are similar, with a maximum in winter and a minimum in summer, which is dominated by the terrestrial ecosystem. However, the seasonal variations of CO2 at BJ and XH are more affected by human activities as compared to XL. By using CO2 at XL as the background, CO2 enhancements are observed simultaneously at BJ and XH. The diurnal variations of CO2 are driven by the boundary layer height, photosynthesis and human activities at BJ, XH and XL. Moreover, we address the impact of the wind on the CO2 mole fractions at BJ and XL. This study provides an insight into the spatial and temporal variations of CO2 mole fractions in North China.

scholarly journals Анизотропия анионной проводимости в монокристаллах суперионного проводника CeF-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (9) ◽  
pp. 1376
Author(s):  
Н.И. Сорокин ◽  
В.В. Гребенев ◽  
Д.Н. Каримов
Keyword(s):  
Electrical Conductivity ◽  
Atomic Structure ◽  
Unit Cell ◽  
Conductivity Measurements ◽  
Weak Anisotropy ◽  
Tysonite Structure ◽  
Maximum Value ◽  
Anisotropy Effect ◽  
First Time ◽  
Anionic Conductivity

The anisotropy of anionic conductivity in crystals of a superionic conductor CeF3 with the tysonite structure (sp. gr. P-3с1) has been studied for the first time. The conductivity measurements at temperatures from 300 K to 600 K were carried out along the principal a- and c-axes of trigonal unit cell of the crystal. The maximum value of electrical conductivity is observed along the c-axis. The superionic CeF3 crystals have the weak anisotropy of electrical conductivity equal to σ||c/σ||a = 2.4 and σ||c = 5.6 10–4 S/cm at 500 K. The anisotropy effect of anionic conductivity in individual fluorides with the tysonite structure is discussed in connection with the peculiarities of their atomic structure.

Transport Properties of Type II Sodium-Silicon Clathrates

2005 ◽  
Vol 886 ◽  
Author(s):  
Matt Beekman ◽  
Jan Grkyo ◽  
George S. Nolas
Keyword(s):  
Thermal Conductivity ◽  
Sodium Content ◽  
Type I ◽  
Type Ii ◽  
Conductivity Measurements ◽  
Scanning Calorimetry ◽  
Resistivity Measurements ◽  
Silicon Clathrates ◽  
Covalently Bonded ◽  
First Time

ABSTRACTWe have synthesized the type II silicon clathrates Na1Si136 and Na8Si136, and report on the electrical and thermal transport in these materials. The crystal structure consists of a covalently bonded silicon framework in which sodium guest atoms are encapsulated inside the silicon host framework. Differential scanning calorimetry measurements show the compounds decompose above 600°C to diamond-structure silicon. Temperature dependant electrical resistivity measurements show the specimens to have an insulating character, with magnitudes that decrease with increasing sodium content. For the first time, thermal conductivity measurements on type II sodium-silicon clathrates are presented. The thermal conductivity is very low for both specimens, and for Na8Si136 exhibits a clear dip in the range from 50 to 70 K. These data suggest that the “rattling” behavior observed in type I clathrates may also be present in type II clathrates.

scholarly journals High Resolution 3-D Imaging of Mesospheric Sodium (Na) Layer Utilizing a Novel Multilayer ICCD Imager and a Na Lidar

2020 ◽  
Vol 12 (22) ◽  
pp. 3678
Author(s):  
Xuewu Cheng ◽  
Guotao Yang ◽  
Tao Yuan ◽  
Yuan Xia ◽  
Yong Yang ◽  
...  
Keyword(s):  
Focal Length ◽  
Horizontal Resolution ◽  
Density Profiles ◽  
Horizontal Structure ◽  
Charge Coupled Device ◽  
Observational Technique ◽  
Intensified Charge Coupled Device ◽  
Cassegrain Telescope ◽  
First Time ◽  
Different Altitudes

Equipped with a 1-meter Cassegrain telescope with 6.2 meter focal length and an electronically gated Intensified Charge-Coupled Device (ICCD), a multilayer Na imager is designed and developed at Wuhan in China. This novel instrument has successfully achieved the first preliminary 3-D image of the mesospheric Sodium (Na) layer when running alongside a Na lidar. The vertical Na layer profile is measured by the lidar, while the horizontal structure of the layer at different altitudes is measured by the ICCD imaging with a horizontal resolution of ~3.7 urad. In this experiment, controlled by the delay and width of the ICCD gating signal, the images of the layer are taken with three-second temporal resolution for every 5 km. The results show highly variable structures in both the vertical and horizontal directions within the Na layer. Horizontal images of the Na layer at different altitudes near both the permanent layer (80–100 km) and a sporadic Na layer at 117.5 km are obtained simultaneously for the first time. The Na number density profiles measured by the lidar and those derived from this imaging technique show excellent agreement, demonstrating the success of this observational technique and the first 3-D imaging of the mesospheric Na layer.

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