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A common feature of fluorescent sensing materials for detecting chemical warfare agents (CWAs) and simulants is the presence of nitrogen-based groups designed to nucleophilically displace a phosphorus atom substituent, with the reaction causing a measurable fluorescence change. However, such groups are also basic and so sensitive to acid. In this study we show it is critical to disentangle the response of a candidate sensing material to acid and CWA simulant. We report that pyridyl-containing sensing materials designed to react with a CWA gave a strong and rapid increase in fluorescence when exposed to Sarin, which is known to contain hydrofluoric acid. However, when tested against acid-free diethylchlorophosphate and di-iso-propylfluorophosphate, simulants typically used for evaluating novel G-series CWA sensors, there was no change in the fluorescence. In contrast, simulants that had been stored or tested under a standard laboratory conditions all led to strong changes in fluorescence, due to acid impurities. Thus the results provide strong evidence that care needs to be taken when interpreting the results of fluorescence-based solid-state sensing studies of G-series CWAs and their simulants. There are also implications for the application of these pyridyl-based fluorescence and other nucleophilic/basic sensing systems to real-world CWA detection. Chemical warfare agents and simulants are commonly detected with fluorescent sensing materials containing nitrogen-based groups, however these groups' basicity can cause false positives in the presence of acids. Here, the authors disentangle the response of pyridyl-containing sensing materials to acid-containing and acid-free Sarin and simulants. [ABSTRACT FROM AUTHOR]

In the field of water content measurement, the calibration of coulometric methods (e.g., coulometric Karl Fischer titration or evolved water vapor analysis) is often overlooked. However, as coulometric water content measurement methods are used to calibrate secondary methods, their results must be obtained with the highest degree of confidence. The utility of calibrating such instruments has been recently demonstrated. Both single and multiple point calibration methods have been suggested. This work compares these calibration methods for the evolved water vapor analysis technique. Two uncertainty estimation approaches (Kragten's spreadsheet and M-CARE software tool) were compared as well, both based on the ISO GUM method. [ABSTRACT FROM AUTHOR]

Moisture content can affect the thermo-physical properties of many materials. Thus sufficient knowledge of this parameter is required to improve product shelf life and quality, reduce waste or enhance process efficiency. The traditional loss on drying methods are still the go-to methods due to their robustness and simplicity. However, their inherent lack of selectivity imposes restrictions. These are overcome with newer techniques such as vaporization coulometric Karl Fischer titration (vap-C-KFT) and evolved water vapor analysis (EWV). The former is a well-established method, but the latter was more recently introduced and the literature available on it is scarce. This work aims to bridge this gap in knowledge and demonstrate the comparability of the EWV to the more established vap-C-KFT. Multiple samples were studied and the data are analyzed along the principles reported recently by INRiM with a few modifications. [ABSTRACT FROM AUTHOR]

Opioid addiction is an escalating problem that is compounded by the introduction of synthetic opiate analogues such as fentanyl. Screening methods for these compound classes are challenged by the availability of synthetically manufactured analogues, including isomers of existing substances. High-field asymmetric-waveform ion mobility spectrometry (FAIMS) utilizes an alternating asymmetric electric field to separate ions by their different mobilities at high and low fields as they travel through the separation space. When coupled to mass spectrometry (MS), FAIMS enhances the separation of analytes from other interfering compounds with little to no increase in analysis time. Addition of solvent vapor into the FAIMS carrier gas has been demonstrated to enable and improve the separation of isomers. Here we investigate the effects of several solvents for the separation of four opioids. FAIMS-MS spectra with added solvent vapors show dramatic compensation field (CF) shifts for opioid [M+H]+ ions when compared to spectra acquired using dry nitrogen. Addition of vapor from aprotic solvents, such as acetonitrile and acetone, produces significantly improved resolution between the tested opioids, with baseline resolution achieved between certain opioid isomers. For protic solvents, notable CF shift differences were observed in FAIMS separations between addition of water vapor and vapors from small alcohols. [ABSTRACT FROM AUTHOR]

Highlight • Near-nozzle-outward deviation was found at low P inj for flash boiling sprays. • Non-uniform vapor formation inside nozzle caused near-nozzle outward deviation. • Far-field inward deviation was found at high P inj for non-flash-boiling and flash boiling sprays. • Jet-induced low pressure zone could occur under non-flash-boiling and flash boiling conditions. Abstract Fuel spray behaviors play an important role in mixture formation, efficiency and emission of internal combustion engines. In this study, the effect of injection pressure on spray jet trajectory was investigated by using an asymmetric five-hole GDI injector. With schlieren imaging method, the ethanol spray development was captured under superheat degrees from 0.46 to 9.48, and the ambient pressure was fixed at 101.3 kPa. For the non-flash-boiling cases, the jet trajectory gradually deviated inward in the far field with the increase of injection pressure. For the flash boiling cases, the jet trajectory near the nozzle exit deviated outward under the relatively low injection pressures and deviated inwards with the increase of injection pressure. The outward deviation under relatively low injection pressure was attributed to the non-uniform vapor formation inside the nozzle orifice. The disappearance of near-field deviation under flash boiling conditions under high injection pressures could be attributed to the reduced time for nucleation and bubble growth inside the nozzle. Additionally, under both non-flash-boiling and flash-boiling conditions, the far-field deviation under high injection pressures could be attributed to the increased jet speed and the stronger jet-to-jet interaction. Compared with non-flash-boiling cases, the far field deviation under flash boiling conditions were more intense because of the enhanced atomization and it is believed that the smaller droplets were more inclined to move inwards. The remarkable effect of injection pressure on jet interaction of flash boiling sprays shows the potential of flexible jet targeting control at different engine loads. [ABSTRACT FROM AUTHOR]

A flexible and physical optimal estimation-based inversion algorithm for retrieving atmospheric water vapor and cloud liquid water path from passive microwave radiometers over the global oceans is presented. The algorithm's main strength lies in its ability to explicitly account for forward model errors that depend on the Earth incidence angle (EIA) at which a given radiometer measurement is made. Validation of total precipitable water (TPW) retrieved fromMicrowave Humidity Sounder (MHS) measurements against near-coincident estimates of TPW from SuomiNet GPS ground stations shows that retrieved TPW values agree closely with SuomiNet estimates, and somewhat better than values from theMicrowave Integrated Retrieval System that are retrieved from the sameMHS instruments.More importantly, it is found that the inclusion of appropriate forward model error assumptions, which are tailored to the EIA and sea surface temperature of the scene being considered, are able to almost entirely eliminate EIA-dependent biases in retrieved TPW. This result holds true across all satellites currently carrying an MHS instrument, despite the fact that only measurements from one satellite are used to estimate forward model errors. The consistency achieved by the retrieval algorithmacross all view angles suggests that other inversion algorithms, particularly those for cross-track-scanning radiometers and potential future constellations of small satellites, would benefit from the inclusion of nuanced error assumptions that consider the effect of EIA. [ABSTRACT FROM AUTHOR]

Nearly all plant families, represented across most major biomes, absorb water directly through their leaves. This phenomenon is commonly referred to as foliar water uptake. Recent studies have suggested that foliar water uptake provides a significant water subsidy that can influence both plant water and carbon balance across multiple spatial and temporal scales. Despite this, our mechanistic understanding of when, where, how, and to what end water is absorbed through leaf surfaces remains limited. We first review the evidence for the biophysical conditions necessary for foliar water uptake to occur, focusing on the plant and atmospheric water potentials necessary to create a gradient for water flow. We then consider the different pathways for uptake, as well as the potential fates of the water once inside the leaf. Given that one fate of water from foliar uptake is to increase leaf water potentials and contribute to the demands of transpiration, we also provide a quantitative synthesis of observed rates of change in leaf water potential and total fluxes of water into the leaf. Finally, we identify critical research themes that should be addressed to effectively incorporate foliar water uptake into traditional frameworks of plant water movement. Despite being represented across numerous plant families and providing a notable water subsidy to plants, the process of foliar water uptake is still poorly understood. This review addresses the need for a cohesive synthesis of the processes that drive foliar uptake, the pathways of water movement, and the role of this water in plant water budgets. In addition to these components, we address the critical knowledge gaps needed for a more complete understanding of this nearly ubiquitous process. [ABSTRACT FROM AUTHOR]

Experimental investigations of evaporation heat transfer of R22 and R410A inside a horizontal micro-fin copper tube have been conducted and are reported here. Six micro-fin tubes with inner diameter of 7.14 mm and three micro-fin tubes with inner diameter of 8.8 mm but with different geometric parameters, such as the apex angle, the helical angle, fin height, fin pitch, and starts were tested. The evaporation experiments were taken at a constant temperature of 6°C. Moreover, working conditions of the experiments varied with the mass flux ranging from 100 kg/(m2.s) to 400 kg/(m2.s). For the evaporation experiments of Tube 1 - Tube 6 with R22, the inlet and outlet vapor quality is set as 0.1 and 0.9, respectively. For the evaporation experiments of Tube 7 - Tube 9 with R410A, the inlet and outlet vapor quality is set as 0.2 and 0.9, respectively. The heat transfer coefficients and the changing trend of the heat transfer coefficients vary among these tubes. The influence of each geometric parameter on the heat transfer performance of the micro-fin tube has been analyzed and is reported. Besides, correlations of evaporation heat transfer inside 8.8 mm or less horizontal round micro-fin tubes were developed. [ABSTRACT FROM AUTHOR]

Controlling internal flow in evaporating sessile droplets is desirable across applications ranging from lab-on-chip medical diagnostics, DNA profiling to surface patterning. Diffusion limited evaporation in droplets exhibit very low internal flow velocities [∼O(10−6) m/s]. Enhancement of internal flow is useful for applications which demand in situ mixing at small scale fluidic systems but limited by the low Reynolds number. To overcome this limitation, we present a non-intrusive methodology to enhance flow inside the droplets without affecting its global evaporation pattern. A highly volatile ethanol droplet is positioned asymmetrically in the vicinity of a water droplet. The ethanol molecules are consequently adsorbed asymmetrically on the air-water interface creating a gradient in surface tension. This causes an internal Marangoni convection with flow rates ∼O (103) times higher than a naturally evaporating water droplet. The inter-droplet distance between ethanol-water is used as a control parameter to vary the strength of Marangoni convection. The flow pattern transitions through several regimes from asymmetric to symmetric double toroid once the ethanol droplet completely evaporates. Experimental flow visualization and quantification by micro-particle image velocimetry have been used alongside simple scaling arguments to quantify the physical mechanism at play. We can also switch between different flow patterns by strategic dispensing of ethanol droplets. [ABSTRACT FROM AUTHOR]

Highlights • A post-dryout heat transfer correlation for developing regime was validated over a wide range of flow conditions. • The dryout location is estimated using the CHF look-up table. • Good prediction results are obtained over wider pressure conditions. Abstract The present paper deals with the validation of a post-dryout heat transfer correlation, which has been proposed by Nguyen and Moon (2015), to show its extended applicability to developing post-dryout region. It is also shown that the well-known film-boiling look-up table (LUT) method currently having limited application to fully-developed flow can be improved to extend its applicability to the developing post-dryout region. In order to show that the correlation can be utilized for nuclear reactor safety analysis, eight different sets of post-dryout data covering flow conditions both in both large break loss-of-coolant accident (LB LOCA) and prolonged station blackout (SBO) scenarios have been assessed. It turns out that the correlation predicts well the measured wall temperature with a total average error of 3.81% and a root-mean-square error of 13.46% in case of given CHF (dryout) condition. The prediction accuracy of the correlation is strongly influenced by how well the local vapor temperature and the CHF locations can be predicted. [ABSTRACT FROM AUTHOR]

Satellite remote sensing of the atmospheric water vapor distribution over the oceans is essential for both weather and climate studies. Satellite onboard microwave radiometer is capable of measuring the water vapor over the oceans under all weather conditions. This study assessed the accuracies of precipitable water vapor (PWV) products over the south and east China seas derived from the Global Precipitation Measurement Microwave Imager (GMI), using radiosonde and GNSS (Global Navigation Satellite System) located at islands and coasts as truth. PWV measurements from 14 radiosonde and 5 GNSS stations over the period of 2014–2017 were included in the assessments. Results show that the GMI 3-day composites have an accuracy of better than 5 mm. A further evaluation shows that RMS (root mean square) errors of the GMI 3-day composites vary greatly in the range of 3∼14 mm at different radiosonde/GNSS sites. GMI 3-day composites show very good agreements with radiosonde and GNSS measured PWVs with correlation coefficients of 0.896 and 0.970, respectively. The application of GMI products demonstrates that it is possible to reveal the weather front, moisture advection, transportation, and convergence during the Meiyu rainfall. This work indicates that the GMI PWV products can contribute to various studies such as climate change, hydrologic cycle, and weather forecasting. [ABSTRACT FROM AUTHOR]

Highlights • A new splitter is proposed, which can regulate the vapor split ratio. • The allocation rule of the vapor splitter is obtained. • The vapor uniformity is increased by optimizing the position of the splitter. Abstract In order to lower the difficulty to control the vapor split ratio of divided wall column (DWC) and to optimize auto-allocated vapor flow rate on the both side of the divided wall in real industry, this paper presents a new vapor ratio regulator. The splitter, which is based on the Coanda effect, is installed in the bottom section of the DWC to control vapor flow rate on both sides of the DWC and solve the problem of vapor allocation in the DWC. In this research, Auto-cad, computational, Tecplot, and Origin are used to do data analysis. By tracking the vapor flow trajectory and analyzing the splitter's allocation rule, it is shown that the R V can be effectively regulated by adjusting the velocity of the gas inlet. In order to achieve a high uniformity of the vapor flow field of regulator, the installation location of the device is optimized. [ABSTRACT FROM AUTHOR]

EI Niño–Southern Oscillation (ENSO) is a complex ocean-atmosphere interaction phenomenon occurring in nature that has a profound impact on global atmospheric circulation. As ENSO is a coupled ocean-atmosphere phenomenon, in addition to the commonly used sea surface temperature (SST), water vapor in the atmosphere can be used to monitor the evolution of ENSO and to investigate its consequences (e.g., droughts and flooding). The Global Navigation Satellite System (GNSS), in addition to its applications for positioning, timing, and navigation, is another established atmospheric observing system used to remotely sense precipitable water vapor (PWV) in the atmosphere. The accuracy of the GNSS-derived PWV measurements was assessed from 12 stations based on observations made at co-located radiosonde stations as a reference. The results show that mean values of the root-mean-square error (RMSE) and biases of 6-hourly GNSS-derived PWV derived from all 12 stations are valued at 1.48 mm and −0.30 mm, respectively. Regarding monthly means, mean values of the RMSE and biases of the GNSS-derived PWV are valued at 0.66 mm and −0.23 mm, respectively. The variability in PWV estimated from 56 GNSS stations positioned close to the sea indicates that it is significantly affected by ENSO events. Generally, a 1-K increase in SST will lead to an 11% increase in PWV across all of the stations. A case study conducted at the TOW2 station in Australia shows that the non-linear trend of the PWV depicts the evolution of two severe flood events and one severe drought event occurring in this region. Comparative results derived from TOW2 and from another 24 stations show a good agreement between PWV and total precipitation. These results suggest that GNSS-derived PWV together with other climatic variables (e.g., SST) can be used as an indication of the evolution of ENSO events and as a possible indicator of drought and flood occurrence. [ABSTRACT FROM AUTHOR]

Laminar film condensation in upward and downward vapor flows is numerically investigated by using a sharp-interface level-set method to track the condensate film surface and accurately calculating the phase-change mass flux under the saturation temperature condition at the interface. An analytical model for steady laminar film condensation in upward as well as downward vapor flows is developed to validate the present numerical results. As the vapor velocity increases, the condensation rate is observed to decrease in upward vapor flows whereas it increases in downward vapor flows. The effects of vapor velocity and wall temperature on laminar film condensation in upward and downward vapor flows are investigated. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework (ZIF) membranes are emerging as a promising energyefficient separation technology. However, their reliable and scalable manufacturing remains a challenge. We demonstrate the fabrication of ZIF nanocomposite membranes by means of an all-vapor-phase processing method based on atomic layer deposition (ALD) of ZnO in a porous support followed by ligand-vapor treatment. After ALD, the obtained nanocomposite exhibits low flux and is not selective, whereas after ligand-vapor (2-methylimidazole) treatment, it is partially transformed to ZIF and shows stable performance with high mixture separation factor for propylene over propane (an energy-intensive high-volume separation) and high propylene flux. Membrane synthesis through ligand-induced permselectivation of a nonselective and impermeable deposit is shown to be simple and highly reproducible and holds promise for scalability. [ABSTRACT FROM AUTHOR]

The macroscopic characteristics of clouds in the Tibetan Plateau are crucial to understanding the local climatic conditions and their impact on the global climate and water vapor cycle. In this study, the variations of cloud cover and cloud types are analyzed by using total-sky images of two consecutive years in Shigatse, Tibetan Plateau. The results show that the cloud cover in Shigatse presents a distinct seasonal difference that is characterized by low cloud cover in autumn and winter and high cloud cover in summer and spring. July is the month with the largest cloud coverage, and its average cloud cover exceeds 75%. The probability of clouds in the sky is the lowest in November, with an average cloud cover of less than 20%. The diurnal variations of cloud cover in different months also have considerable differences. Specifically, cloud cover is higher in the afternoon than that in the morning in most months, whereas the cloud cover throughout the day varies little from July to September. The dominant cloud types in different months are also not the same. The proportion of clear sky is large in autumn and winter. Stratiform cloud occupies the highest percentage inMarch,April, July, and August. The probability of emergence of cirrus is highest in May and June. The Shigatse region has clear rainy and dry seasons, and correlation analysis between precipitation and clouds shows that the largest cumulative precipitation, the highest cloud cover, and the highest proportion of stratiform clouds occur simultaneously in July. [ABSTRACT FROM AUTHOR]

This study presents a model for quantifying the performance of primary nozzles within the context of ejectors in the refrigeration systems. The effects of real and ideal gas properties are compared and two equations for the two-phase speed of sound are tested against experimental data for vapor nozzles working with R245fa, N 2 and R141b and also a two-phase nozzles processing CO 2 . Results show that the predicited performance of ejector nozzles based on the ideal gas assumptions can be greatly different from that based on the real fluid properties. For the two-phase nozzle the value of the speed of sound is important as it was found to be because errors in this lead to large differences in the nozzle performance and even predictions of nozzle efficiency values greater than one. It is expected that this paper and the study described within will be useful for those wishing to model or design ejector nozzles and contributes to the further understanding of related investigations, especially on the two-phase nozzle. [ABSTRACT FROM AUTHOR]

Electronic cigarettes regulation in Indonesia has not been set yet. In the last 4 years the electronic cigarettes have been widely distributed and used in Indonesia. Electronic cigarettes contain nicotine, propylene glycol, glycerol, liquid flavors, etc. All ingredients produce vapor when heated. Vapor and particles from electronic cigarettes affect the human health. Formaldehyde is known as a product of propylene glycol and glycerol vapor degradation. Formaldehyde is one of the chemical agents categorized as carcinogen. The aim of the research was to analyze the identification of formaldehyde vapor concentration and health complaint of electronic cigarettes smoker. The research was conducted in Surabaya city, Indonesia, from October 2015 to December 2016. The research used cross-sectional approach. Sample was obtained by purposive sampling that fulfilled samples inclusion criteria. The variables were the onset of smoking electronic cigarettes, smoking frequency of electronic cigarettes, formaldehyde vapor concentration, cotinine urine, and health complaint of electronic cigarettes smoker. The result showed that formaldehyde concentration in six vapors varied while cotinine urine mostly was positive. It is suggested to educate people about hazard of electronic cigarettes and to conduct further research to identify chemical agent in electronic cigarettes. [ABSTRACT FROM AUTHOR]

The knowledge of atmospheric column water vapor concentration is crucial for compensating water absorption effects in remote sensing data. Several algorithms for the estimation of such a parameter were proposed in the past. One of the most effective algorithms is the atmospheric precorrected differential absorption (APDA) technique. APDA relies on a simplified radiative transfer model (RTM) that does not account for the spatial variability of the adjacency effects. In this paper, we study the impact of the simplified RTM assumption on the performance of the algorithm by exploiting a more realistic and well-established RTM. Starting from such a model, we derive a new water retrieval algorithm called low-rank subspace projection-based water estimator. It exploits the high degree of spectral correlation experienced in the reflectances of most of the existing materials. An extensive experimental analysis is carried out on simulated data in order to assess and compare the performance of the two algorithms. Simulation results allow the critical analysis of the two algorithms by highlighting their strengths and drawbacks. [ABSTRACT FROM AUTHOR]

In this study, the reaction kinetics for a heterogeneous oxidation reaction of elemental mercury (Hg(0)) vapor with CuCl 2 was studied in a fixed-bed reactor using 2%(wt) CuCl 2 /α-Al 2 O 3 between 100 and 180 °C for Hg(0) oxidation after air preheater at a typical coal-fired power plant. The reaction rate expression was first order with respect to Hg(0). However, between 100 and 180 °C, CuCl 2 over α-Al 2 O 3 agglomerates and sinters. This sintering effect added significant mass-transfer resistance to the diffusion of Hg(0) vapor, and thus made the conversion of CuCl 2 incomplete. Therefore, a grain model was formulated to determine the rate constant by taking into account the mass-transfer resistance. The model constituted a two parameter estimation problem for the determination of the rate constant and product layer diffusivity. The model predictions with the two optimum parameters were in good agreement with the experimental data. The activation energy value determined from the rate constant values was significantly lower than those for other Hg(0) oxidation catalysts under HCl and O 2 gases reported in the literature. This result corroborates that CuCl 2 can enhance Hg(0) oxidation by lowering the activation energy barrier with the reduction of Cu(2+) to Cu(1+) and supplying thermally stable surface Cl sites following a Mars-Maessen mechanism. CuCl 2 -based catalyst has potential to be applied after air preheater for Hg(0) oxidation followed by the separation of Hg(2+) in wet flue gas desulfurization (FGD) system or by activated carbon (AC) injection. [ABSTRACT FROM AUTHOR]

The smartphone camera presents a convenient, portable, and low-cost innovation in colorimetric measurements. In this paper, a smartphone camera was applied for the colorimetric detection of gaseous elemental mercury, an atmospheric pollutant of concern in environment, and workplace monitoring. A cuprous iodide (CuI)/polystyrene composite was used as the recognition element, which exhibited a reddish color in the presence of Hg0. Digital images of the sensing reagent phase were captured by a smartphone camera and were analyzed in red-green-blue color space using ImageJ, an open source image processing program. Parameters for the digital colorimetric sensing including the color values, polymer reagent binder, amount of CuI, exposure time, and Hg0 concentration were investigated and optimized. The linear working range of the sensor was from 61 to 270 μg/m3 Hg0 with a correlation coefficient of 0.978. The limit of detection is 16 μg/m3 Hg0. This method shows the feasibility of applying a smartphone camera for a simple, reliable, and inexpensive colorimetric measurement of Hg0 vapor in a gas mixture such as air. [ABSTRACT FROM AUTHOR]

The results of a study on aluminum welding by direct-current straight polarity arc in a protective gas environment (argon, helium) are presented. The welding arc burns in aluminum vapor; the condensation products consequently lower the temperature of the welding column in the anode region. The condensation products of aluminum are formed by the cluster mechanism with the formation of fractal thread-like structures. The clustering mechanism is characterized by the release of nondissociated molecular blocks of aluminum into the vapor state. They form a morphologically complex composition of the alumina film on the surface of the weld pool during condensation. [ABSTRACT FROM AUTHOR]

A flexible conductive polymer nanofiber composite (FCPNC) was prepared by carbon nanotube (CNT) decoration onto the blend polyurethane (PU)/Polyethersulfone (PES) nanofibers under the assistance of ultrasonication. CNTs were uniformly distributed on the nanofiber surface, which was beneficial to the construction of electrically conductive network. The obtained composite mat possessed an ultralow percolation threshold of 0.056 vol%, and the electrical conductivity was as high as 2.8 S m −1 at a relatively low CNT concentration of 0.85 vol%. Also, the introduction of CNTs increased both the tensile strength and Young's modulus of the nanofiber mat. The FCPNC with good electrical conductivity and interconnected porous structures was then used as a chemical vapour sensor, which was based on the change of the distance among the conductive nanofibers and hence the electrical conductivity, resulting from the adsorption and desorption of organic vapours. The sensing selectivity of the FCPNC was determined by the solubility parameters as well as the saturated vapour pressure. When the FCPNC with a CNT content of 0.5 vol% was exposed to the acetone vapour, the response intensity ( R I ) could reach ∼8.8 × 10 2 , while the response rate ( R R ) was only 9 s. The resistance was able to return to its original value when the sample was taken out from the vapour to air, and the R I could retain 90% after tenth cycle test, displaying a good reproducibility. [ABSTRACT FROM AUTHOR]

The departure from nuclear boiling (DNB) is an essential point for the heating channel with water flowing through, because when it happens, the water near the heated wall can be dried out, which will cause the material temperature exceeding the upper limits. Presently, the blanket is under design phase, and some essential parameters are uncertain, including the heat flux on the first wall (FW). For the sake of thermal safety, the occurrence conditions of DNB are analyzed solely, regardless whether material temperature exceeds the limits or not, in the FW of water-cooled ceramic breeder blanket for Chinese Fusion Engineering Reactor. This paper is useful for further blanket thermal design. Based on the lookup table that is summarized by experiments for the uniformed heating circular tube of 8 mm diameter, the local critical volumetric fraction of vapor, which acts as the evaluation criteria for the U-shaped FW of square channel with one-sided heating, is obtained using a computational fluid dynamics approach under different DNB operating conditions. After the comparison of phase distribution between different turbulence models, the K– $\Omega $ model is selected to do the calculation. The effects of coolant inlet temperature, mass flow rate, and operating pressure on DNB value are evaluated. Under the same operating pressure, either increasing mass flux or decreasing inlet temperature can reduce the critical vapor fraction. On the contrary, the DNB is enlarged effectively. Under the same inlet conditions, the lower operating pressure can increase DNB because of the higher latent heat of vaporization. [ABSTRACT FROM AUTHOR]

Superheated emulsions develop visible vapor bubbles when exposed to ionizing radiation. They consist in droplets of a metastable liquid, emulsified in an inert matrix. The formation of a bubble cavity is accompanied by sound waves. Evaporated bubbles also exhibit a lower refractive index, compared to the inert gel matrix. These two physical phenomena have been exploited to count the number of evaporated bubbles and thus measure the interacting radiation flux. Systems based on piezoelectric transducers have been traditionally used to acquire the acoustic (pressure) signals generated by bubble evaporation. Such systems can operate at ambient noise levels exceeding 100 dB; however, they are affected by a significant dead time (>10 ms). An optical readout technique relying on the scattering of light by neutron-induced bubbles has been recently improved in order to minimize measurement dead time and ambient noise sensitivity. Beams of infra-red light from light-emitting diode (LED) sources cross the active area of the detector and are deflected by evaporated bubbles. The scattered light correlates with bubble density. Planar photodiodes are affixed along the detector length in optimized positions, allowing the detection of scattered light from the bubbles and minimizing the detection of direct light from the LEDs. A low-noise signal-conditioning stage has been designed and realized to amplify the current induced in the photodiodes by scattered light and to subtract the background signal due to intrinsic scattering within the detector matrix. The proposed amplification architecture maximizes the measurement signal-to-noise ratio, yielding a readout uncertainty of 6% (±1 SD), with 1000 evaporated bubbles in a detector active volume of 150 ml (6 cm detector diameter). In this work, we prove that the intensity of scattered light also relates to the bubble size, which can be controlled by applying an external pressure to the detector emulsion. This effect can be exploited during the readout procedure to minimize shadowing effects between bubbles, which become severe when the latter are several thousands. The detector we used in this work is based on superheated C-318 (octafluorocyclobutane), emulsified in 100 μm ± 10% (1 SD) diameter drops in an inert matrix of approximately 150 ml. The detector was operated at room temperature and ambient pressure. [ABSTRACT FROM AUTHOR]

We report the adsorption properties of methanol (ML) and ethanol (EL) vapor molecules on to the monolayer MoSe 2 surface. Before, studying the adsorption behavior, the structural stability of MoSe 2 monolayer is ensured with formation energy. The stable monolayer MoSe 2 nanosheet is used as a base material for the adsorption of ML and EL vapor molecules. The interaction of ML and EL vapors on MoSe 2 surface layer is explored using the adsorption energy, energy gap variation and Bader charge analysis. We noticed the band gap variation between 1.43 and 1.88 eV upon adsorption of methanol and ethanol vapors on to MoSe 2 nanosheets. Also the adsorption energy is found in the range of −0.375 to −0.732 eV upon the interaction of alcohol molecules on MoSe 2 flakes. Besides, the density of states (DOS) spectrum and electron density clearly envisions the adsorption properties of ML and EL vapors on to the MoSe 2 monolayers. Furthermore, a short recovery time is noticed for MoSe 2 nanosheet material upon desorption of methanol and ethanol molecules. Moreover, the variation in the resistance of MoSe 2 base material is noticed upon adsorption of ML and EL molecules. The findings show that monolayer MoSe 2 nanosheets can be used as a chemi-resistance to detect the presence of ML and EL vapors in the environment. [ABSTRACT FROM AUTHOR]

Photochemical vapor generation (PVG) is emerging as a promising analytical tool for Te determination, thanks to its efficient matrix separation, and simple and green procedure. However, the low PVG generation efficiency of Te is the bottleneck for its wide application in environmental samples containing trace Te. Herein, we reported a high efficient PVG for Te determination by synergistic effect of ferric ion and nano-TiO2. The analytical sensitivity was enhanced approximately 15-fold for Te(IV) in the presence of both ferric ions and nano-TiO2, comparing to conventional PVG. Besides, the use of nano-TiO2 can provide Te(VI) and Te(IV) an equal and high PVG efficiency in the presence of ferric ions, owned to the high photocatalytic performance of TiO2 under short-wavelength UV irradiation (254 and 185 nm). Under the optimized experimental conditions, a detection limit of 1.0 ng L-1 was obtained. The precision of replicate measurements was 2.3% (RSD, n = 7) at 0.5 µg L-1 for Te(IV). The methodology was validated by successful determination of Te in surface waters and two standard reference sediment samples. To our best knowledge, this is the first report of the synergistic enhancement of transitional metal ions and nano-TiO2 in PVG, which possesses potential for highly sensitive determination of vapor-forming elements. [ABSTRACT FROM AUTHOR]

A highly sensitive method based on UV photochemical vapor generation capacitively coupled plasma microtorch optical emission using a low resolution microspectrometer was developed for total mercury determination in food and water. The method fulfils most of the eco-scale criteria in terms of derivatization and cost-effective miniaturized instrumentation, which are major benefits compared to cold vapor atomic fluorescence spectrometry and inductively coupled plasma optical emission spectrometry. Formic acid was the single reagent used for the extraction of Hg species from solid samples and as a reaction medium for the UV photo-induced cold vapor generation. A 200 mg lyophilized sample was subjected to ultrasonic assisted extraction in 10 mL of HCOOH 98–100% at 50 °C for 3 h, and then on-line derivatization to cold vapor was performed in 0.6 mol L−1 HCOOH. Water and food with low Hg content adjusted in HCOOH 0.6 mol L−1 underwent on-line preconcentration of Hg vapor on a gold filament microcollector. Total Hg was quantified against external standards containing Hg2+ by recording emission at 253.652 nm in a low power/Ar consumption (15 W/100 mL min−1) plasma source with a Maya2000 Pro (Ocean Optics) microspectrometer. The proposed method was compared with common laboratory approaches based on derivatization with SnCl2 and detection by inductively coupled plasma optical emission spectrometry/atomic fluorescence spectrometry, and thermal decomposition atomic absorption spectrometry. The limits of detection obtained without/with preconcentration were 3.5/0.1 ng L−1 in solution and 9/0.25 μg kg−1 in the solid, much better than those in the reference methods. The proposed method was found to be free from interference coming from multimineral matrices and organic matter, and suitable for sample analysis with various matrices as it provided a recovery of Hg without/with preconcentration of 101 ± 7%/101 ± 12% in food and 97 ± 12% in water. [ABSTRACT FROM AUTHOR]

This research article attempts to investigate the dynamic behavior of the heptads' effect evaporator (HEE) used to concentrate the weak black liquor during the Kraft recovery process in a paper industry. In order to fully characterize the HEE unit, a complete understanding of its performance for steady state and transient conditions is required. For this purpose, a set of first order nonlinear differential equations have been developed for the backward feed flow configuration (BFFC) for an unsteady state. Further, the developed non-linear model is linearized and linear state space equations obtained. The dynamic response of the system in terms of vapor temperature and liquor concentration changes for different changes in input liquor flow rate has been investigated. The rise, delay and settling times for the temperature deviation from steady state have been found to be significantly less as compared with that for the concentration deviation. The results also indicate that each effect of HEE acts as an individual first order system. The placement of such first order systems in series makes both the liquor concentration and vapor temperatures response more sluggish progressively with each subsequent effect. Finally, a Cascade-PID control strategy has been implemented and shown to exhibit differentiated and improved dynamic performance of the HEE system versus open-loop dynamic response. [ABSTRACT FROM AUTHOR]

Purpose This paper aims to gain a clear understanding of the ventilated cavity evolution around an NACA0015 hydrofoil by using both experimental and numerical investigation.Design/methodology/approach The bubble evolution around an NACA0015 hydrofoil with or without air injection was observed in a water tunnel, and the simulation was conducted using a modified turbulence model and homogeneous cavitation model.Findings The present simulation method can successfully predict the bubble evolutions around the NACA0015 hydrofoil with or without air injection. Air injection can alleviate the nature cavitation oscillation, and the suppression effect on nature cavitation depends on the air-entrant coefficient. It is confirmed that the air and vapor cavity have the same shedding frequency. It is seen that the air sheet closely attaches to the hydrofoil surface and is surrounded by the vapor sheet. Thus, the injected air promotes vapor growth and results in an increase in the cavity shedding frequency. Further, with a large air-entrant coefficient, the pressure fluctuation is suppressed completely.Originality/value The new simulation method is adopted to explore the mechanism of ventilated cavitation. The bubble evolutions with and without air injection have been comprehensively studied by experimental and numerical investigation. The effects of air injection on natural cavity oscillations and pressure fluctuations have been revealed in the present study. [ABSTRACT FROM AUTHOR]

Flexible epidermal tattoo and textile-based electrochemical biosensors have been developed for vapor-phase detection of organophosphorus (OP) nerve agents. These new wearable sensors, based on stretchable organophosphorus hydrolase (OPH) enzyme electrodes, are coupled with a fully integrated conformal flexible electronic interface that offers rapid and selective square-wave voltammetric detection of OP vapor threats and wireless data transmission to a mobile device. The epidermal tattoo and textile sensors display a good reproducibility (with RSD of 2.5% and 4.2%, respectively), along with good discrimination against potential interferences and linearity over the 90–300 mg/L range, with a sensitivity of 10.7 µA∙cm 3 ∙mg −1 (R 2 = 0.983) and detection limit of 12 mg/L in terms of OP air density. Stress-enduring inks, used for printing the electrode transducers, ensure resilience against mechanical deformations associated with textile and skin-based on-body sensing operations. Theoretical simulations are used to estimate the OP air density over the sensor surface. These fully integrated wearable wireless tattoo and textile-based nerve-agent vapor biosensor systems offer considerable promise for rapid warning regarding personal exposure to OP nerve-agent vapors in variety of decentralized security applications. [ABSTRACT FROM AUTHOR]

So far, it remains a great challenge to construct organic vapor sensor that can simultaneously achieve high sensitivity, wide detection range, and fast response. Herein, we demonstrate the fabrication of organic vapor sensor based on poly(styrene-butadiene-styrene)/carbon nanotube (SBS/CNT) hybrid fiber using the scalable wet spinning process. The SBS/CNT hybrid fiber-based vapor sensor exhibits a high sensitivity in wide workable detection range (e.g. responsivity of 19% and 256% for 10% acetone and cyclohexane vapors, respectively), rapid response time (≤40 s), good reproducibility as well as excellent mechanical reliability. Moreover, such sensor can quantitatively detect the concentration of organic vapor of as low as 2% in the atmosphere. Such performances demonstrate their great potential applications in wearable and flexible electronics for VOCs monitoring. [ABSTRACT FROM AUTHOR]

The feasibility of detecting explosives in the atmosphere at concentrations as low as 0.01 ppq hinges on the poorly known question of what interfering species exist at these or higher concentrations. To clarify the issue, hundreds of samples of ambient air, either clean or loaded with explosives (from lightly contaminated environments) have been collected in fiberglass/stainless steel filters coated with Tenax-GR, thermally desorbed at variable temperature, and ionized with Cl- via secondary electrospray (SESI). They are analyzed with a narrow-band mobility filter (SEADM's P5 DMA) and a triple quadrupole mass spectrometer (Sciex's 5500), configured in series to transmit precursor and fragment ions of the explosives Nitroglycerin, PETN, RDX, and TNT. Blanks were sampled outdoors at a rural site (Boecillo, Valladolid, Spain), and loads were sampled at diverse locations. For RDX and TNT, atmospheric background inhibits detection below 1 part/trillion (ppt) without mobility filtering. This interference was drastically reduced by the DMA, allowing detection up to 1 part/quadrillion (ppq). Further sensitivity increase was achieved by scanning over a mobility region several percent around that of the target explosive, to separate various isobaric compounds by Gaussian deconvolution. (i) All four MS/MS channels analyzed exhibit several background peaks within the narrow mobility intervals investigated. At least one of these interferents is much stronger than the instrument background at the explosive's mobility, making DMA separation most helpful. (ii) For Nitroglycerin and PETN the combined filtering techniques have not lowered ambient chemical noise down to 0.01 ppq. (iii) Interferents are greatly reduced for TNT and RDX, resulting in minimal chemical noise: 322 blank tests for RDX yielded mean signal of 0.0012 ppq and standard deviation σ = 0.0035 ppq (mean + 3σ detection limit of 0.01 ppq). [ABSTRACT FROM AUTHOR]

This paper presents some preliminary experimental measurements collected during flow boiling heat transfer of low global warming potential refrigerant R1234yf in an asymmetrically heated rectangular plain channel. The asymmetrical heating is the common boundary condition that occurs in many different applications, for instance, in almost all the electronic devices, which are now pushing the cooling demands to more and more greater requirements. From this standpoint, the analysis of the flow boiling heat transfer of efficient and eco-friendly refrigerants can open new frontiers to the electronic thermal management. The experimental measurements were carried out at the Department of Industrial Engineering of the University of Padova by imposing two different heat fluxes, 50 and 100 kW m−2, at a constant saturation temperature of 30°C; the refrigerant mass velocity was varied between 50 and 200 kg m−2s−1, while the vapor quality varied from 0.2 to 0.95. The developed measuring technique permits to estimate the flow boiling heat transfer coefficient and the critical value of vapor quality at the onset of the dryout. [ABSTRACT FROM AUTHOR]

The planet's atmosphere holds a vast amount of water. Existing state-of-the-art “atmospheric water generation” systems mostly work by cooling the entire air flow below the dew point, which require significant amounts of energy per liter of water. As a result, the cost of this water is similar to that of imported bottled water in small single-use plastic containers. Therefore, there is an urgent need for any technology that generates usable water in an energy-efficient manner. It is known that the native dipole moment of water molecule results in the nucleation of liquid phase on carriers of electrical charge due to the suppressed evaporation. Nevertheless, the practical implementation of electrostatic water nucleation (EWN) is still in the stage of laboratory demonstrations. This work summarizes the theoretical background of the phenomenon and past experimental data, presents further experimental results and new data from practical implementation of EWN, and analyzes options for the further development. [ABSTRACT FROM PUBLISHER]

The results of numerical calculations of the vapor bubble dynamics in deuterated acetone are given. [ABSTRACT FROM AUTHOR]

This paper focuses on the inter-comparison of integrated water vapor (IWV) products derived from the following satellite instruments: Global Ozone Monitoring Instrument (GOME-2), Moderate-Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites, Ozone Monitoring Instrument (OMI), Spining Enhanced Visible and InfraRed Imager (SEVIRI), Atmospheric Infrared Sounder (AIRS), and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). IWV data from GPS in nine ground-based stations located in the Iberian Peninsula are used as reference. The study period extends from 2007 to 2012. The results show that, in general, OMI has good accuracy (pseudomedian of the relative differences between OMI and GPS IWV of ( −0.7 ± 1.1) % ). However, OMI, SCIAMACHY and AIRS show higher inter-quartile range (IQR) (which indicates lower precision) than the rest of satellite instruments. Both MODIS satellite instruments and SEVIRI products tend to slightly underestimate reference IWV data while GOME-2 exhibits a notable overestimation (16.7 ± 0.8 % ). All satellite instruments showed a tendency to reduce IWV extreme values: low IWV is overestimated while high IWV is underestimated. As for the influence of solar zenith angle (SZA), it can be observed that GOME-2 strongly overestimates the reference for high SZA values (by around 60 % for SZA 60 − 80°). OMI shows, however, a high IQR for high SZA values. Both MODIS instruments show an increase in the pseudomedian of relative differences and IQR with SZA at daytime, with more stable values at night. Seasonal dependence is mainly due to the SZA and IWV typical values in each season. In general, in summer the tendency is to underestimate with low IQR (which happens when IWV is high and SZA is low), and in winter the trend is to overestimate with high IQR (which happens when IWV is low and SZA is high). SCIAMACHY shows a high pseudomedian in summer and autumn, and lower in winter and spring. It must be noted that GOME-2 shows a higher overestimation and OMI shows a higher IQR than other satellite instruments in winter and autumn. The influence of clouds was also studied, showing an increase of IQR as cloudiness increases in all satellites. Pseudomedian also worsens as cloudiness increases, generally. [ABSTRACT FROM AUTHOR]

The present study investigates the phenomenon of steam condensation in a rectangle horizontal channel with a mass flux range of 20–70 kg/m2/s and a vapor quality of 0.2–0.8. Mass flux and vapor quality were presented to primarily affect the heat transfer coefficient in shear-dominated flow regime, such as the mass flux is greater than 40 kg/m2/s. At the low mass flux, only slug flow, plug flow, and wave flow were observed. At the high mass flux, the wave flow and annular flow were observed even at the low-vapor quality, and the slug and plug flow were not found during the entire condensation process. Observed flow patterns agreed with Tandon’s flow pattern map. Four kinds of correlations are employed to predict the condensing heat transfer coefficient, and the result reveals that Cavallini’s correlation agrees with the experimental results relatively well. The measured pressure drop has a good agreement with the Lockhart–Martinelli correlation. [ABSTRACT FROM PUBLISHER]

Typical trace vapor analysis involves sorbent trapping, followed by desorption and chromatographic separation. This communication describes a method for streamlining this process by combining sorbent sampling/preconcentration with partial separation achieved through temperature-programmed thermal desorption. A novel sorbent trap was formulated in which tubular glass liners for a programmable-temperature gas chromatograph inlet were coated with a sol-gel based polymer stationary phase synthesized from methyltrimethoxysilane precursor and installed into the inlet, which was directly connected to a mass-selective detector by a fused silica capillary transfer line. This method is shown to achieve partial separation of two nitroaromatic vapors in a total 3–5 min analysis time, which represents a tenfold improvement in speed in terms of the overall cycle time compared to an analogous conventional vapor analysis method. Both analytes proved to have a high dynamic range and loading capacity, with nitrobenzene achieving both high and low sampling extremes (0.32 ng–4 μg sampling concentration) with only a slight compromise in peak broadening. The multivariate curve resolution by alternating least squares algorithm (MCR-ALS) was shown to successfully resolve the overlapped elution profiles of the two nitroaromatic test vapors examined in this study. [ABSTRACT FROM AUTHOR]

Various ionization methods in mass spectrometry (MS) are available for the analysis of analytes with different properties. Nonetheless, the use of a single ionization method to analyze mixtures containing analytes with different polarities and volatilities in different phases at atmospheric pressure remains a challenge. Exploring an ionization method that can ionize small organics and large biomolecules with different properties for MS analysis is advantageous. Carbon fiber ionization mass spectrometry (CFI-MS), which uses a carbon fiber bundle as the ion source, is useful for the analysis of small organics with low polarities. Voltage needs to be applied on the carbon fiber bundle to initiate corona discharge for ionization of analytes. In this study, we explore the suitability of using CFI-MS in the analysis of analytes in vapor, liquid, and solid phases using a single carbon fiber (length : ∼1 cm; diameter: ∼10 μm) as the ion source. Furthermore direct electric contact on the carbon fiber is not required. We demonstrate that CFI-MS is useful for analyzing not only small and low-polarity organics but also polar biomolecules, such as peptides and proteins. The limits of detection for analytes with high polarities such as dodecyl trimethylammonium bromide and bradykinin are estimated to be ∼16 and ∼53 pM, respectively. Ionization mechanisms, including corona discharge and electrospray, are involved in the ionization of analytes with the polarity from low to high. Furthermore, sesame oil containing aromatic volatiles and compounds with different polarities is used as a model sample to demonstrate the capability of the developed ionization method to provide comprehensive chemical information from a complex sample. In addition, the feasibility of using the developed method for quantitative analysis of nonpolar as well as medium and high polarity analytes is also demonstrated. The sensitivity of the developed method toward analytes with high polarity is higher than those with low polarity. The method precision was estimated to be ∼7.8%. [ABSTRACT FROM AUTHOR]

Atmospheric Hg measurements are commonly carried out using Tekran® Instruments Corporation's model 2537 Hg vapor analyzers, which employ gold amalgamation preconcentration sampling and detection by thermal desorption (TD) and atomic fluorescence spectrometry (AFS). A generally overlooked and poorly characterized source of analytical uncertainty in those measurements is the method by which the raw Hg atomic fluorescence (AF) signal is processed. Here I describe new software-based methods for processing the raw signal from the Tekran® 2537 instruments, and I evaluate the performances of those methods together with the standard Tekran® internal signal processing method. For test datasets from two Tekran® instruments (one 2537A and one 2537B), I estimate that signal processing uncertainties in Hg loadings determined with the Tekran® method are within ±[1%C 1.2 pg] and ±[6%C0.21 pg], respectively. I demonstrate that the Tekran® method can produce significant low biases (⩾5 %) not only at low Hg sample loadings (<5 pg) but also at tropospheric background concentrations of gaseous elemental mercury (GEM) and total mercury (THg) (~1 to 2 ngm-3/ under typical operating conditions (sample loadings of 5-10 pg). Signal processing uncertainties associated with the Tekran® method can therefore represent a significant unaccounted for addition to the overall ~10 to 15% uncertainty previously estimated for Tekran®-based GEM and THg measurements. Signal processing bias can also add significantly to uncertainties in Tekran®-based gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) measurements, which often derive from Hg sample loadings <5 pg. In comparison, estimated signal processing uncertainties associated with the new methods described herein are low, ranging from within ±0.053 pg, when the Hg thermal desorption peaks are defined manually, to within ±[2%C0.080 pg] when peak definition is automated. Mercury limits of detection (LODs) decrease by 31 to 88% when the new methods are used in place of the Tekran® method. I recommend that signal processing uncertainties be quantified in future applications of the Tekran® 2537 instruments. [ABSTRACT FROM AUTHOR]

The heat transfer coefficient and pressure drop of R32 flow boiling in horizontal mini channels were investigated. The working conditions cover 1 and 2 mm channel inner diameters, 10–20 °C saturation temperatures, 50–600 kg m −2 s −1 mass fluxes, 10–30 kW m −2 heat fluxes and 0–1 vapor qualities. At high mass fluxes, the heat transfer coefficient increases with increasing vapor quality in slug, churn and annular flow, and then sharply decreases after dryout; at low mass fluxes, the heat transfer coefficient gradually decreases with increasing vapor quality in stratified flow. The heat transfer coefficient increases with decreasing channel size and increasing saturation temperature, mass flux or heat flux before dryout. The dryout quality, ranges from 0.7 to 0.9, increases with increasing channel size and decreasing saturation temperature, mass flux or heat flux. The pressure drop firstly increases and then decreases with increasing vapor quality. The pressure drop increases with decreasing channel size or saturation temperature and increasing mass flux or heat flux. Flow-pattern based predict methods were established with 92% of the heat transfer coefficient predictions and 90% of the pressure drop predictions being within ±25% of the experimental data including the previous and present studies. [ABSTRACT FROM AUTHOR]

Isobaric vapour-liquid equilibria (VLE) experimental results for binary systems of 1-(methoxymethoxy)-2-methyl-propane with 1-butanol and isobutanol at 101.33 kPa were determined. Each binary mixture shows a minimum boiling azeotrope at 101.33 kPa, in which the azeotropic temperature and composition are 381.19 K and 26.72 mol% (1-butanol) and 377.55 K and 53.34 mol% (isobutanol), respectively. The VLE measurements were correlated by the van Laar, Wilson and NRTL models for which the binary interaction parameters are reported. The results show that the measurements of two binary systems provide a good agreement with the calculated values acquired by the Wilson and NRTL models, respectively. The thermodynamic consistency of the VLE measurements was checked using the traditional area test and the direct test methods. [ABSTRACT FROM AUTHOR]

Vaporization thermodynamics of the Ga 2 O 3 –ZnO system was studied by the Knudsen effusion technique in combination with mass spectrometric analysis of the vapor phase in the temperature range 1360–1460 K. The incongruent character of vaporization processes in the whole composition range of the Ga 2 O 3 –ZnO system was established. The vapor composition and the partial pressures of the gas phase species were determined. The p – x projection of the Ga 2 O 3 –ZnO phase diagram at 1410 K was constructed. The standard molar enthalpy of formation of ZnGa 2 O 4 at 298 K was found to be −1472.8 ± 26.6 kJ·mol −1 . [ABSTRACT FROM AUTHOR]

This report presents a simple and efficient method of layer thinning and p-type doping of WSe2 with vapor XeF2. With this approach, the surface roughness of thinned WSe2 can be controlled to below 0.7 nm at an etched depth of 100 nm. By selecting appropriate vapor XeF2 exposure times, 23-layer and 109-layer WSe2 can be thinned down to monolayer and bilayer, respectively. In addition, the etching rate of WSe2 exhibits a significant dependence on vapor XeF2 exposure pressure and thus can be tuned easily for thinning or patterning applications. From Raman, photoluminescence, X-ray photoelectron spectroscopy (XPS), and electrical characterization, a p-doping effect of WSe2 induced by vapor XeF2 treatment is evident. Based on the surface composition analysis with XPS, the causes of the p-doping effect can be attributed to the presence of substoichiometric WO x ( x < 3) overlayer, trapped reaction product of WF6, and nonstoichiometric WSe x ( x > 2). Furthermore, the p-doping level can be controlled by varying XeF2 exposure time. The thinning and p-doping of WSe2 with vapor XeF2 have the advantages of easy scale-up, high etching selectivity, excellent controllability, and compatibility with conventional complementary metal-oxide-semiconductor fabrication processes, which is promising for applications of building WSe2 devices with versatile functionalities. [ABSTRACT FROM AUTHOR]

The boiling liquid expanding vapor explosion (BLEVE) is a most common hazard in liquefied gas storage and transportation. The explosion is resulted from tank overpressure under external thermal attack, and its prevention depends on accurate prediction of the boiling liquid pressurization. This paper presents a mathematical model to simulate the boiling liquid pressurization in liquefied gas storage tank. The model includes a semi-empirical equation to calculate the critical subcooled degree at the onset of pressurization, an energy equation of bubble condensation to calculate the net vapor generation rate in storage tank, a thermal-response equation of the subcooled boiling liquid to calculate the transient temperature of bulk liquid, and an isochoric equation to predict the transient pressure of boiloff liquefied gas. Comparison of the model predictions with experimental data shows that the maximum deviations of the predicted transient pressure and temperature are within 15 kPa and 3 °C, respectively. [ABSTRACT FROM AUTHOR]

The pressure drop fluctuation of two-phase flow in single horizontal mini-channels with diameters of 1.2 mm, 1.6 mm and 2.0 mm was experimentally investigated. Degassed water was tested in circular horizontal mini-channels with diameters of 1.2 mm, 1.6 mm and 2.0 mm at liquid mass fluxes of 21.2, 42.4 and 84.8 kg m −2 s −1 as well as heat fluxes of 0–216 kW m −2 . The pressure drop and the mini-channel wall temperature profiles as well as the visualization results were recorded. Three basic types of the two-phase flow pressure drop fluctuation were identified based on the characteristic frequency, i . e . the low-frequency fluctuation ( f < 2.0 Hz), the medium-frequency fluctuation (2.0 Hz < f < 10.0 Hz) and the high-frequency fluctuation ( f > 10.0 Hz). Besides, it was found that there existed three types of superimposed-frequency fluctuation. Pressure drop fluctuation maps were presented for three diameter channels, showing the single-phase region, the superimposed-frequency region and the low-frequency fluctuation region. The pressure drop fluctuation region depends on the ratio of the heat flux and the mass flux and the channel diameter. The periodic vapour catapult phenomenon was found during the low-frequency fluctuation, which was inferred to be caused by the bubbly/annular alternating flow pattern transition. It was found that the pressure drop and the wall temperature had the approximate fluctuation period with the periodic vapour catapult process. The medium-frequency fluctuation and the high-frequency fluctuation are related to the passage of the elongated bubbles with different periods. In superimposed medium and high frequency fluctuation, the amplitude of the pressure drop fluctuation is relatively low and no synchronous fluctuation was observed between wall temperature and pressure drop profiles. [ABSTRACT FROM AUTHOR]

This research project involved a comparison between the performance of active and passive sampling methods used to collect isopropyl alcohol vapor in an industrial setting. This field experiment was conducted in a real-world industry setting with workers exposed to isopropyl alcohol. In order to create sample sets, passive diffusive samplers (3M 3520 Organic Vapor Monitor) were paired, side-by-side, with active samplers (charcoal solid sorbent tubes). A total of 17 paired sample sets were collected, which yielded data with a non-parametric distribution. Post hoc analysis showed that 4 of the 17 paired sample sets were potential outliers. A Wilcoxon signed-rank test showed that the passive samplers were significantly different from the active air samples (alpha = 0.05), regardless whether or not the potential outliers were included or excluded from the data. A linear regression analysis found a linear relationship between active and passive sampling results. An R 2 value of 0.97 (when including potential outliers) and 0.79 (when excluding potential outliers) suggests that the model fits well with the data. Satisfactory correlation between the samplers was found when including potential outliers (r = 0.9859) and excluding potential outliers (r = 0.8863). The passive samplers reported higher concentrations than the active samplers in 15 of the 17 sample sets. On average, the passive samplers reported 25% higher results when including potential outliers and 16% higher results when excluding potential outliers when compared to the paired active sampling results. Based on the strong correlation values and the trend of passive samplers reporting higher results than the active samplers, occupational health specialists could reliably use the passive samplers in this study to demonstrate compliance to isopropyl alcohol exposure limits. [ABSTRACT FROM AUTHOR]

Nitrogen seeding, necessary for divertor heat-load mitigation in ITER, has been shown to lead to ammonia formation which would be a severe operational and safety issue in ITER. Predictions of ammonia production in ITER are based on data from present day fusion devices. Ammonia is mainly detected by residual gas analysis (RGA). Detection of ammonia is impeded by the presence of water and methane which, in a mixed H-D system, leave signatures in the same range of the mass spectra. A statistical model is used to ascribe an average isotope ratio to each gaseous species. The model is tested with simulated RGA recordings with varying concentration of ammonia to evaluate the sensitivity to fitting parameter boundaries, noise in the recordings and mis-matching cracking patterns. The analysis shows that the fitting procedure may in some occasions substitute species among each other, resulting in faulty concentrations. Nevertheless, the right choice of parameter boundaries ensures correct fitting results. Finally, the fitting procedure is applied to experimental data from nitrogen-seeeded discharges at AUG and JET. [ABSTRACT FROM AUTHOR]