Measured Water Concentrations Research Articles

Noncontact high sensitivity chipless tag microwave resonator for bitumen concentration measurement at high temperatures

Real-time water concentration measurement in bitumen is critically important during all operating processes from extraction to refining. Having a low-cost, noncontact sensor that can operate in high temperatures is vital in terms of energy conservation, process optimization and elapsed time. This paper presents a specific design of a microwave coupled split ring resonator-based sensor, with a ground-gap-coupled transmission line as the reader. The tag is a metallic trace with the theoretical capability to sense in ultra-high temperatures far beyond the maximum temperature used in bitumen refineries and is electromagnetically coupled the reader, enhancing the coupling distance up to 60 mm. Therefore, the proposed sensor is well adapted to measure in harsh environmental conditions. Various simulations are conducted and compared against experimental results, verifying the features for the introduced sensor such as the capability to measure at temperatures higher than 200 °C, extremely high sensitivity of 500 kHz (1% of water concentration variation) and measurement in both steady-state and turbulent conditions.

Role of water in degradation of nitroplasticizer

The role of water in degradation of nitroplasticizer (NP) was studied using a set of NP samples aged inside confined containers between room temperature and 70∘C with their water concentrations monitored during the aging course. For the first 42 days at the temperatures 55∘C and below, simple Fickian diffusion dominates the monotonic decreases of the water concentrations with time. After about 60–80 days depending on temperatures, diffusion alone can no longer explain the water decreases, despite no significant NP degradation detectable using the FTIR spectroscopy. Starting at about 80–160 days, also depending on temperatures, the measured water concentrations fluctuated around mean values that decrease with increasing temperature, and the onset of NP degradation was detected using FTIR and TGA. It was found that NP contains an irreducible amount of water on the order of a few hundred ppms, which decreases with increasing temperature. Pristine NP does not exist with a water concentration lower than this amount. The diffusivity, the irreducible amount of water in NP, and the mean water production rate due to NP degradation are calculated from the water concentrations of the first aging stage and the mean water concentrations during the onset of NP degradation. They all change with the temperature following Arrhenius laws with different prefactors and activation energies. This study shows that trace water formation is an intrinsic property of the NP while it ages with the mechanistic details to be resolved.

(Invited) Zirconia-Based Electrochemical Oxygen Sensor for Monitoring Humidity at the Cathode of PEM Stacks

One of the greatest challenges associated with PEMFCs is the water balance in thefuel cell stack. Depending upon the load and the operating conditions, the fuel cell membranes have a propensity to both flood and dry-out. If the PEM is not adequately humidified, the conductivity of the protons decreases, which causes reduced performance. Excess water also can create an issue by inhibiting the reactants from diffusing to the catalyst sites by flooding of the electrodes and gas channels if the water removal is insufficient. Current humidity sensing technologies are not capable of meeting the demands required for this harsh environment. Zirconia-based electrochemical sensors for measuring the oxygen concentration in the automotive exhaust have been used on vehicles for nearly 40 years. This oxygen sensor is an electrochemical cell based on oxygen-ion conducting zirconia operated at elevated temperatures (> 400°C). The sensor is a simple Nernst cell that consists of a single electrochemical cell with one electrode exposed to a reference atmosphere (typically air) and the other electrode exposed to the measurement (exhaust) gas. Although successfully used for stoichiometric A/F control for many years, Nernst-type oxygen sensors are not useful for applications away from stoichiometry because of their weak logarithmic dependence of the emf on oxygen partial pressure. Single and double-zirconia-cell sensors have been developed which have much higher sensitivity and thus a wider range of operation. These are amperometric sensors are based on oxygen pumping, which involves the transfer of oxygen from one side of a zirconia cell to the other by passing an electric current through the device. Since these sensors operate over a wide range, they are referred to as “wide-range oxygen” or “universal exhaust gas oxygen” (UEGO) sensors and can be used over a broader range of A/F measurement and control. All gasoline vehicles, as well as diesel powertrains which operate lean, employ UEGO sensors to meet the emission requirements. The double-cell amperometric sensor also can be used to measu­re the concentration of other oxygen-containing molecules, e.g. H2O, CO2, SO2, and NOx. In order to mea­sure the H2O concentration for example, a voltage is applied across the pump-cell that is greater than the dissociation potential for H2O. The resulting oxygen generated from the decomposition of water is then measured via an increase in pumping current by the UEGO sensor and is proportional to the H2O concentration in the gas. If other oxygen-containing molecules are present in the measurement gas, the voltage across the pump cell can be varied over the dissociation potentials of these gases. For H2O/air mixtures, the concentration of oxygen can be measured at a lower potential. A second voltage larger than the dissociation potential of the measurement gas, H2O, is applied to measure the concentration of oxygen plus water. The water concentration can be determined by subtracting the pumping current due to oxygen from the pumping current due to the combination of the two gases. Other gases can also be measured in a similar fashion. These measurements can be achieved without any modification to the existing sensor hardware. A simple modification to the electronic control circuitry is all that is required to perform this type of measurement. Figure 1 shows the sensitivity of a commercially available UEGO sensor for the dissociation of H2O as a function of dissociation potential. A typical operating value for the sensing voltage Vs for oxygen measurement is 450 mV. The plot below was generated from data measured in the lab at various water concentrations in a carrier gas of dry nitrogen. From the plot it is evident that water dissociation is occurring at potentials less than 800 mV. Additionally, the output begin to saturate at a potential approaching 1100 mV, suggesting that full dissociation of the water has been achieved. Figure 2 shows the sensitivity (pumping current) of the same sensor as a function of water concentration for Vs = 1080 mV. Once again the carrier gas is dry nitrogen. The output is linear in water concentration. The water balance at the cathode is particularly difficult to manage because water accumulates due to the reaction and the clogging of the small channels. Controlling this water balance requires accurate water concentration measurements at temperatures approaching 100°C and pressures up to 3 bar absolute. The application of this humidity sensing technology to measure the water concentration at the cathode of PEMFCs will be discussed. Figure 1

Improved Water Management of Electrospun Nanofiber Membrane Electrode Assemblies at High Current Densities Measured in Operando Using Neutron Radiography

Neutron radiography was used to measure water concentrations through the cross-sections of sprayed gas diffusion electrodes (GDE) and electrospun perfluorosulfonic acid-platinum nanofiber (NF) electrodes during fuel cell operation. The performance of Generation 1 poly(acrylic acid)-based NF electrodes is improved at high current densities compared to the baseline given by a GDE cell. Through-thickness water profiles reveal that at high current densities, the water concentrations within the membrane electrode assembly (MEA) and gas diffusion layers are around 2x lower in the nanofiber-containing MEA compared to the baseline GDE, commensurate with the observed polarization performance. In Generation 2 electrospun nanofiber electrodes, poly(ethylene oxide)-based electrodes show higher performance than poly(acrylic acid) electrodes, while retaining less water in the MEA. These results imply that the electrospun nanofiber electrodes have an improved ability to maintain hydration without flooding, which leads to improved performance over a range of relative humidities.

Effects of the insecticide esfenvalerate on zooplankton in an indoor synthetic model ecosystem.

Effects of esfenvalerate on zooplankton and their recovery potential were studied using an indoor synthetic model ecosystem. Esfenvalerate was applied to the system by direct spiking to overlying water or the introduction of treated slurry soil to imitate drift and run-off exposure. Four zooplankton taxa, Daphnia magna (Cladocera), Heterocypris incongruens (Ostracoda), Cyclops sp. (Copepoda), and Brachionus calyciflorus (Rotifera), were exposed to esfenvalerate with Raphidocelis subcapitata (green alga). In a drift scenario, lower doses (0.02-0.5 µg/L) showed slight or negligible effects, but the results for the highest dose (5 µg/L) indicated direct effects, as remarkable population decreases were observed for three taxa (except rotifera). However, for the latter dose, results of weekly or single (Day-15) zooplankton re-introductions after dosing demonstrated resilient recovery. In a run-off scenario, a nominal dose of 20 µg/L, in which the measured water concentrations remained at 3-6%, had effects similar to those of the high drift exposure scenario for cladocera and ostracoda.

Single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water concentration and temperature within the annulus of a rotating detonation engine

Abstract A novel single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water mole fraction and temperature was developed and deployed within the annulus of a hydrogen/air-fed rotating detonation engine (RDE). The sensor transmitted two laser beams targeting mid-infrared water transitions through a single optical port on the outer wall of the cylindrical RDE annulus and measured the backscattered radiation from the RDE inner surface using a photodetector for a round-trip path of 1.52 cm. Optimizing the sensor's optical arrangement using numerical ray tracing to minimize interference from optical emission, beam steering, and scattered laser light from window surfaces was essential to sensor performance. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization was implemented to allow for frequency-domain multiplexing of the two lasers and to suppress non-absorbing interference sources such as beam-steering and emission. Tunable diode lasers near 2551 and 2482 nm were modulated at 100 and 122 kHz, respectively, and sinusoidally scanned across the peaks of their respective water transitions at 10 kHz to provide a measurement rate of 20 kHz and detection limit of 0.5% water by mole. Experimentally derived spectroscopic parameters enabled water and temperature sensing with respective uncertainties of 7.3% and 5.3% relative to the measured values. Time-resolved and time-averaged sensor measurements of gas temperature and water vapor mole fraction allow quantitative evaluation of the combustion progress at the measurement location and thus provide a design tool for RDE optimization. Broadly, this single-ended laser sensor should find applications in other combustion systems where optical access is limited.

Dynamics of a powerful deep submarine eruption recorded in H2O contents and speciation in rhyolitic glass: The 2012 Havre eruption

Constraining the syn-eruptive volatile contents of magmatic melt is critical to understanding the intensities and styles of deep submarine volcanic eruptions, for which direct observations are scarce. Quantifying residual magmatic water contents in volcanic glass is complicated by rehydration, i.e., late-stage addition of molecular water. The 2012 deep submarine silicic eruption of Havre volcano provides an unusual opportunity to quantify glass water contents from a recent, well-sampled stratigraphic sequence. Fourier-transform infrared and microRaman spectroscopy measurements of water concentration and water speciation across the Havre 2012 eruptive sequence reveal an unanticipated range of excess molecular water within pumice. This excess water requires rapid timescales of diffusion that are inconsistent with our current understanding of low temperature secondary rehydration in both subaerial and subaqueous eruptive products. Diffusion models applied to enrichment profiles at vesicle edges confirm that low temperature rehydration is an unlikely cause. We instead support higher temperature, syn-eruptive pumice rehydration by condensed magmatic water and seawater in a submarine plume. Hydroxyl concentrations suggest shallow quenching depths of Havre pumice hundreds of meters above the 900-meter-deep main vent. Our data also support the presence of a vapor-rich plume and consequent modification of ocean pressure above the vent. We combine this novel volatile data with textural information and cooling rate calculations to explore the conditions that would cause slower, shallow cooling of clasts from a deep submarine eruption. By exploring the physical conditions for the interaction between pumice and submarine plumes, we emphasize fundamental differences between subaerial and submarine clast-producing eruptions.

Terahertz time-domain spectroscopy for non-invasive assessment of water content in biological samples.

We apply terahertz time-domain spectroscopy for the quantitative non-invasive assessment of the water content in biological samples, such as Carpinus caroliniana tree leaves and pork muscles. The developed experimental terahertz time-domain spectroscopy system operates both in transmission and reflection modes. The Landau-Looyenga-Lifshitz-based model is used for the calculation of the water concentration within the samples. The results of the water concentration measurements are compared with the results of the gravimetric measurements. The obtained results show that the water content in biological samples can be measured non-invasively, with a high accuracy, utilizing terahertz waves in transmission and reflection modes.

Isotopic insights into the degassing and secondary hydration of volcanic glass from the 1980 eruptions of Mount St. Helens

Abstract The magmatic degassing history of newly erupted volcanic glass is recorded in its remaining volatile content. However, this history is subsequently overprinted by post-depositional (secondary) hydration, the rates and origins of which are not yet adequately constrained. Here, we present the results of a natural experiment using products of the 1980 eruptions of Mount St. Helens. We measured water concentration, δDglass, and δ18OBSG (δ18O of the bulk silicate glass) of samples collected during the dry summer months of 1980 and compared them with material resampled in 2015 from the same deposits. Samples collected from the subsurface near gas escape pipes show elevated water concentrations (near 2.0 wt%), and these are associated with lower δDglass (− 110 to − 130‰) and δ18OBSG (6.0 to 6.6‰) values than the 1980 glass (− 70 to − 100‰ and 6.8 to 6.9‰, respectively). Samples collected in 2015 from the surface to 10-cm subsurface of the 1980 summer deposits have a small increase in average water contents of 0.1–0.2 wt% but similar δ18OBSG (6.8–6.9‰) values compared to the 1980 glass values. These samples, however, show 15‰ higher δDglass values; exchange with meteoric water is expected to yield lower δDglass values. We attribute higher δDglass values in the upper portion of the 1980 deposits collected in 2015 to rehydration by higher δD waters that were degassed for several months to a year from the hot underlying deposits, which hydrated the overlying deposits with relatively high δD gases. Our data also contribute to magmatic degassing of crystal-rich volcanoes. Using the 1980 samples, our reconstructed δD-H2O trends for the dacitic Mount St. Helens deposits with rhyolitic groundmass yield a trend that overlaps with the degassing trend for crystal-poor rhyolitic eruptions studied previously elsewhere, suggesting similar behavior of volatiles upon exsolution from magma. Furthermore, our data support previous studies proposing that exsolved volatiles were trapped within a rapidly rising magma and started degassing only at shallow depths during the 1980 eruptions.

Volatile concentrations in olivine-hosted melt inclusions from meimechite and melanephelinite lavas of the Siberian Traps Large Igneous Province: Evidence for flux-related high-Ti, high-Mg magmatism

The origin of high-Mg melts remains one of the most highly debated questions in igneous petrology. There are two contrasting points of view, namely, (1) melt initiation in a rising high-temperature plume, and (2) mantle melting due to fluxing by water. To address this question we determined H2O, CO2, F, Cl and S concentrations in olivine-hosted melt inclusions of high-Mg volcanic rocks of the Siberian Traps Large Igneous Province that bracket the main pulse of volcanism at about 252–250 Ma, and can be classified as melanephelinites and meimechites. Both rock types belong to the high-Ti rock series. Correcting measured H2O, CO2, F, Cl and S concentrations in homogenized primary meimechite melt inclusions to primary meimechite melt composition using experimental melt compositions resulted in corrected melt-inclusion, volatile compositions of ~3.88 wt% H2O, ~1477 ppm CO2, ~4214 ppm F, ~2.08 wt% Cl and ~2490 ppm S. These values are viewed as minimum estimates for the original volatile concentrations in the melt because of the high probability for degassing during melt crystallization and/or during experiment homogenization. Olivine-hosted homogenized melt inclusions from melanephelinites yielded lower corrected concentrations of ~1.06 wt% H2O, ~998 ppm CO2, ~3242 ppm F, ~607 ppm Cl and ~2131 ppm S. We also measured water concentrations in clinopyroxenes of melanephelinites by FTIR, obtaining values as high as 133 ppm H2O, which corresponds to 0.91 wt% in the melt, in general agreement with data obtained by SIMS on the olivine-hosted melt inclusions. Olivine grains from melanephelinites are characterized by evolved compositions (Fo 0.80–0.86). Extrapolation to a primitive melanephelinite melt by simple fractional crystallization suggests that it could also contain high H2O concentrations (up to ~ 3 wt%). Analyzed meimechite and melanephelinite whole-rock samples are characterized by trace-element patterns that are typical of mantle-derived melts and by Sr-Nd isotope ratios that exclude crustal contamination or derivation from ancient lithospheric mantle. Thus, high volatile concentrations can be attributed to sublithospheric mantle source regions. This supports the notion that high-Mg melts form by volatile fluxing of the asthenospheric mantle rather than by decompression melting under relatively dry conditions of a rising abnormally high-temperature mantle plume.

The role of water in extraction and separation of rare earth elements in supercritical carbon dioxide

Rare earth elements can be complexed with tributyl phosphate, thus forming a metal-ligand complex which is soluble in supercritical CO2. In this study, neodymium and holmium nitrate were extracted into supercritical CO2 with varying amounts of tributyl phosphate (from 8 to 80 mM) and water (from 0 to 200 mM). Temperature was held at 60 °C and pressure ranged from 17 to 28 MPa. UV–vis spectroscopy was used to measure supercritical metal concentrations, and near-IR spectroscopy was used to measure water concentrations. It was found that holmium is preferentially extracted over neodymium, with the greatest separation occurring when the molar ratio of tributyl phosphate to lanthanides was approximately 1–2, and when no water was added. Affinity constants were fit to the data. The results suggest that a soluble Ho(NO3)3·2TBP·H2O complex accounts for the preferential extraction of holmium, especially at lower water and tributyl phosphate concentrations.

High-throughput in Vitro Data To Inform Prioritization of Ambient Water Monitoring and Testing for Endocrine Active Chemicals.

The presence of industrial chemicals, consumer product chemicals, and pharmaceuticals is well documented in waters in the U.S. and globally. Most of these chemicals lack health-protective guidelines and many have been shown to have endocrine bioactivity. There is currently no systematic or national prioritization for monitoring waters for chemicals with endocrine disrupting activity. We propose ambient water bioactivity concentrations (AWBCs) generated from high throughput data as a health-based screen for endocrine bioactivity of chemicals in water. The U.S. EPA ToxCast program has screened over 1800 chemicals for estrogen receptor (ER) and androgen receptor (AR) pathway bioactivity. AWBCs are calculated for 110 ER and 212 AR bioactive chemicals using high throughput ToxCast data from in vitro screening assays and predictive pathway models, high-throughput toxicokinetic data, and data-driven assumptions about consumption of water. Chemical-specific AWBCs are compared with measured water concentrations in data sets from the greater Denver area, Minnesota lakes, and Oregon waters, demonstrating a framework for identifying endocrine bioactive chemicals. This approach can be used to screen potential cumulative endocrine activity in drinking water and to inform prioritization of future monitoring, chemical testing and pollution prevention efforts.

Application of a Relative Humidity Sensor for Monitoring Water Vapor Concentration inside Enclosures

The presence of water can have adverse effects on the performance of mechanical and electrical hardware. Standing or condensed water can cause shorting or grounding issues in the short term and can accelerate corrosion in the long term. High humidity can also accelerate corrosion as well as cause swelling of electrical components, seals, or composite materials. Water exposure data can be used to actively intervene prior to degradation(e.g. to fix a water leak) or to calculate the remaining life of a system that has been exposed to water or high humidity. The U.S. Army has recognized the importance of environmental monitoring and failure prediction in weapon systems to ensure readiness, to enhance safety, and toimprove weapon performance. Since 2000, Picatinny Arsenal has sponsored the development of specialized environmental monitoring sensors with on-board diagnostics in various new weapon/ammunition systems. In this article we present an effort at the Pacific Northwest National Laboratory to develop an asset health monitor to assess water concentration inside the storage container of an artillery shell. Desiccant is used in the container to maintain the water vapor concentration below 5000 parts per million; a higher water concentration would indicate container leakage or the need to replace the desiccant. Various types of water sensors, including standing water indicators, corrosion indicators, and humidity sensors, were identified and categorized according to type of water exposure, accuracy, and response time. A commercially available relative humidity sensor was identified as a cost effective approach to measuring water vapor concentration inside the container. Relative humidity can be converted to waterconcentration using the water vapor saturation pressure at ambient temperature. Using diurnal temperature simulations, it was determined that the accuracy of the relative humidity sensor would be unsatisfactory in high temperature/low humidity situations where a small change in relative humidity results is a large change in water vapor concentration. To overcome this obstacle, a strategic sampling technique was developed to increase the accuracy of the water concentration measurement that is based on relative humidity sensor data. The relative humidity sensorwas integrated into the Remote Readiness Asset Prognostic/Diagnostic System (RRAPDS), which is an asset health monitor developed by PNNL to measure environmental conditions in munition containers. RRAPDS will be secured to the container with a probe that extends into the container to monitor internal temperature and humidity. RRAPDS includes a microcontroller to process environmental data and execute diagnostic routines. Thispaper will describe the approach that was developed to estimate water concentration using relative humidity sensor data and describe the sampling technique used to maximize the accuracy of the water vapor concentration assessment.

Leaching losses from Kenyan maize cropland receiving different rates of nitrogen fertilizer

Meeting food security requirements in sub-Saharan Africa (SSA) will require increasing fertilizer use to improve crop yields, however excess fertilization can cause environmental and public health problems in surface and groundwater. Determining the threshold of reasonable fertilizer application in SSA requires an understanding of flow dynamics and nutrient transport in under-studied, tropical soils experiencing seasonal rainfall. We estimated leaching flux in Yala, Kenya on a maize field that received from 0 to 200 kg ha−1 of nitrogen (N) fertilizer. Soil pore water concentration measurements during two growing seasons were coupled with results from a numerical fluid flow model to calculate the daily flux of nitrate-nitrogen (NO3−-N). Modeled NO3−-N losses to below 200 cm for 1 year ranged from 40 kg N ha−1 year−1 in the 75 kg N ha−1 year−1 treatment to 81 kg N ha−1 year−1 in the 200 kg N ha−1 treatment. The highest soil pore water NO3−-N concentrations and NO3−-N leaching fluxes occurred on the highest N application plots, however there was a poor correlation between N application rate and NO3−-N leaching for the remaining N application rates. The drought in the second study year resulted in higher pore water NO3−-N concentrations, while NO3−-N leaching was disproportionately smaller than the decrease in precipitation. The lack of a strong correlation between NO3−-N leaching and N application rate, and a large decrease in flux between 120 and 200 cm suggest processes that influence NO3−-N retention in soils below 200 cm will ultimately control NO3−-N leaching at the watershed scale.

Transport parameters of lead (Pb) Ions migrating through saturated lateritic soil–bentonite column

This paper describes experiments and analyses conducted to determine the transport parameters of lead (Pb) ions diffusing through compacted lateritic soil–bentonite column. Experimental programme included the batch sorption tests and diffusion tests conducted in cells containing water-saturated lateritic soil treated with up to 10% bentonite by dry weight of soil. Specimens for diffusion tests were compacted at approximately 2% wet of optimum moisture content with British standard heavy (BSH) effort and exposed to municipal waste leachate placed on top of the specimens. Migration of Pb ions was monitored by measurement of pore water concentrations at various depths along the soil mixture columns together with the soil transport parameters (i.e. distribution coefficient, Kd, retardation factor, Rd and diffusion coefficient, D*). Based on sorption data, linear sorption isotherms were derived. Kd values of 2.0, 2.2, 2.5, 2.7, 3.9 as well as Rd values of 11.0, 11.1, 12.5, 12.5, 16.7 were recorded for 0, 2.5, 5, 7.5, 10% bentonite contents, respectively. The distribution of Pb was limited to upper sections (1.6–3.2 cm) of the soil column in mixtures. Diffusion testing established D* values of 4.50, 3.15, 2.78, 2.42 and 2.06 × 10−10 m2/s for the same sequence of bentonite treatment which is consistent with very strong sorption on mixtures particularly with higher bentonite contents.

Complex mixtures of Pesticides in Midwest U.S. streams indicated by POCIS time-integrating samplers

The Midwest United States is an intensely agricultural region where pesticides in streams pose risks to aquatic biota, but temporal variability in pesticide concentrations makes characterization of their exposure to organisms challenging. To compensate for the effects of temporal variability, we deployed polar organic chemical integrative samplers (POCIS) in 100 small streams across the Midwest for about 5 weeks during summer 2013 and analyzed the extracts for 227 pesticide compounds. Analysis of water samples collected weekly for pesticides during POCIS deployment allowed for comparison of POCIS results with periodic water-sampling results. The median number of pesticides detected in POCIS extracts was 62, and 141 compounds were detected at least once, indicating a high level of pesticide contamination of streams in the region. Sixty-five of the 141 compounds detected were pesticide degradates. Mean water concentrations estimated using published POCIS sampling rates strongly correlated with means of weekly water samples collected concurrently, however, the POCIS-estimated concentrations generally were lower than the measured water concentrations. Summed herbicide concentrations (units of ng/POCIS) were greater at agricultural sites than at urban sites but summed concentrations of insecticides and fungicides were greater at urban sites. Consistent with these differences, summed concentrations of herbicides correlate to percent cultivated crops in the watersheds and summed concentrations of insecticides and fungicides correlate to percent urban land use. With the exception of malathion concentrations at nine sites, POCIS-estimated water concentrations of pesticides were lower than aquatic-life benchmarks. The POCIS provide an alternative approach to traditional water sampling for characterizing chronic exposure to pesticides in streams across the Midwest region.

Testing the “read-across hypothesis” by investigating the effects of ibuprofen on fish

Human pharmaceuticals present in the environment have the potential to cause adverse effects on non-target organisms. The “read-across hypothesis” stipulates that pharmaceuticals will exhibit similar biological effects across species (e.g. human and fish) if the molecular target has been conserved and the effective drug concentrations are reached (Cmax). We tested this hypothesis by evaluating if ibuprofen, a non-selective inhibitor of prostaglandins and the cyclooxygenase (COX) enzyme, can mimic its primary effect in humans, on fish, at comparable plasma concentrations. The endpoints, prostaglandin E metabolite (PGEM) levels and the mRNA expression of COX (ptgs) gene, were measured in the gills of control and exposed fathead minnows (Pimephales promelas), using enzyme-immunoassay and quantitative real-time PCR (qPCR). Fish were exposed, for 24–72 h, to measured water concentrations of 9 (n = 12), 370 (n = 40) and 470 μg ibuprofen/L (n = 12). Water and blood plasma concentrations were determined using LC-MS/MS. Results showed that PGEM levels in fish exposed to 370 and 470 μg ibuprofen/L were significantly decreased compared to control fish, when mean plasma ibuprofen concentrations were 1.8–5.6-fold below the Cmax. The plasma ibuprofen concentrations and PGEM levels varied greatly between individuals. In fish exposed to 9 μg ibuprofen/L, when the mean plasma ibuprofen concentration was 224-fold below Cmax, no change in PGEM levels was observed. These data provide evidence for the read-across hypothesis, but suggest establishing a direct dose-response between internal plasma and PGEM is difficult, and would require significantly larger numbers of fish to overcome the inter-individual variation.

Anode purge strategy optimization of the polymer electrode membrane fuel cell system under the dead-end anode operation

Dead-ended anode (DEA) mode is commonly applied in fuel cell vehicles for the hydrogen purge at the anode side, to reduce fuel waste and enhance fuel cell efficiency. Anode purge is necessary and is definitely important with respect to removing liquid water and accumulated nitrogen in the gas diffusion layer and the flow field of the DEA-mode fuel cell. In this paper, the effect of different purge strategies on the stack performance and system efficiency is investigated experimentally using fast data acquisition and advanced tools, such as the fast cell voltage measurement (CVM) system and the mass spectrum. From the fast data acquisition, the voltage stability, liquid water and nitrogen concentration measurement in the anode exhaust are compared and analyzed under different purge strategy designs and using different purge valves. The results show that under the optimal purge strategy, the DEA fuel cell stack can achieve the desired stability and system efficiency based on the analysis of the cell voltage and purge volume. Moreover, the diameter of the purge valve has a great impact on the voltage stability because a diameter change will result in a different pressure drop and purge volume when the purge valve is open.

オゾンマイクロバブルを用いた高機能洗浄技術

The removal technology of single-wafer processing using ozone is proposed on photoresist removal in the semiconductor manufacturing. Ozone is friendly for the environment and no harm to the product. Before now, the authors indicated that disk-shaped nozzle forms a vortex structure between the disks which is considered to cause the reduction of photoresist removal rate. This study proposes a disk-shaped convex nozzle to suppress the vortex. In order to investigate the effects of the presence or absence of the convex, the removal experiments were conducted. As a result, disk-shaped convex nozzle had the higher removal ability than disk-shaped nozzle in the convex part. Next, as a new removal method, we suggest the ozone microbubble with a Venturi tube. To investigate the performance of the photoresist removal with it, first, the generation of ozone microbubbles is observed in the Venturi tube via a high speed video camera. Next, to clarify the effect of the superficial liquid and gas velocities, the ozone microbubble, and presence or absence of convex, ozone water concentration measurement and photoresist removal experiments were conducted. As a result, the ozone water concentration increased with increasing superficial velocity and the remaining photoresist thickness reduced. Also, ozone microbubble had the higher removal ability than ozone water single-phase. Compared presence and absence of convex, convex influenced photoresist removal efficiently. In addition, compared with the existing study, it is suggested that the superficial liquid and gas velocities and ozone water concentration affect the photoresist removal rate.

Determining water in transformer paper insulation: analyzing aging transformers

It is important to monitor the water concentration in the insulation of aging power transformers, because over time the insulation becomes wet, due to water ingress from the atmosphere and water formed in chemical reactions involving oxygen. If the water concentration is sufficiently high, the insulation will age prematurely [1] and the transformer may fail if overloaded [2]. In a previous article [3] we reported on the measurement of water concentration in the insulation paper of a power transformer that had been in service for only seven years. The waterconcentration data obtained using on-line water-activity probes were compared with corresponding data obtained from dielectric response measurements. In that work cellulose adsorption isotherms were used to process the water-activity-probe data. However, according to [4] and [5], inaccuracies in the waterconcentration estimates may result from the use of adsorption isotherms. According to [6], these inaccuracies may exceed 200%. The probable main causes are the transformer insulation materials not reaching thermal equilibrium, the water concentration within the insulation not being uniform, and variability in the properties of the insulating materials.