Passage Of Vapor Research Articles

Detection of chemicals in water using a three-dimensional graphene porous structure as liquid-vapor separation filter

In this study, we report the utilization of a three-dimensional (3D) porous graphene structure as liquid–vapor separation filter, which allows the passage of chemical vapors while blocking liquid chemicals and water. The blockage of liquid chemicals and water from semiconducting sensing regions is required to avoid abnormal transistor characteristics. In order to impart omniphobic characteristics, a (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trichlorosilane (HDF-S) self-assembled monolayer was coated on the surface of the 3D porous graphene structure. The concentration of chemical agents in water could be consistently detected by observing the shift in the threshold voltage in the oxide nanowire transistor covered by the HDF-S self-assembled 3D graphene structure. The proposed monitoring method is expected to offer means for application in different environments by providing a stable sensing performance.

Observation of a water droplet motion by using an oxide nanowire transistor covered by a nanofiber mesh

The motion, in particular the flow speed and dropping height, of a water droplet was observed using a tin oxide (SnO2) nanowire transistor with a polyurethane (PU) nanofiber mesh as a selective filter. The changes in the SnO2 nanowire transistor characteristics, particularly the threshold voltage and on-current, were due to the adsorbed water molecules that acted as electron donors on the surface of the oxide nanowire semiconducting channel. The role of the PU nanofiber mesh, allowing the passage of water vapor while blocking liquid water, was to restrict the direct contact between the water droplet and the oxide nanowire semiconducting channel and electrodes, which could cause abnormal transistor characteristics. The selective filtering properties of the PU nanofiber mesh could be controlled by changing the number of PU layers.

Detection of chemical substances in water using an oxide nanowire transistor covered with a hydrophobic nanoparticle thin film as a liquid-vapour separation filter

We have developed a method to detect the presence of small amounts of chemical substances in water, using a Al2O3 nanoparticle thin film covered with phosphonic acid (HDF-PA) self-assembled monolayer. The HDF-PA self-assembled Al2O3 nanoparticle thin film acts as a liquid-vapour separation filter, allowing the passage of chemical vapour while blocking liquids. Prevention of the liquid from contacting the SnO2 nanowire and source-drain electrodes is required in order to avoid abnormal operation. Using this characteristic, the concentration of chemical substances in water could be evaluated by measuring the current changes in the SnO2 nanowire transistor covered with the HDF-PA self-assembled Al2O3 nanoparticle thin film.

Nitrogen Hemioxide: Properties and Neutralization Methods

The physical and chemical properties of N 2 O and methods for its trapping and decomposition are examined. It is found that organic solvents, water, hydrazine hydrate, and a solution of potassium bichromate in sulfuric acid dissolve N 2 O but its stabilization by this method is unreliable. Catalytic decomposition upon heating is acknowledged to be an effective method of neutralizing N 2 O. Different composite materials, including those containing d and ƒ elements, were studied as catalysts. It was found that suitable composites for catalytic decomposition of N 2 O are SiO 2 –Cu, Al 2 O 3 –Ni at 150°C and Al 2 O 3 –Cu, Al 2 O 3 –Fe, Al 2 O 3 –Ni, and SiO 2 –Cu at 250°C. It was shown that the passage of ethanol vapors above the composites at the indicated temperature increases the degree of decomposition of N 2 O by a factor of 10. The results obtained were used to develop a gas-purification system in the technology for reprocessing spent nitride fuel.

Conduit Seals in Hazardous Locations—An Ongoing Safety Issue: The Past and the Future

The use of electrical conduit seals to prevent the release of an explosion from an explosion-proof enclosure and to minimize the passage of flammable vapor and gas migration to an ignition source is as prevalent today as it was yesterday in the petrochemical industry. With the harmonization of international standards and recent equipment advancements, options are available to reduce the use of conduit seals for a more reliable, safe, and maintainable installation. The harmonization of the standards is reviewed, specifically on the International Electrotechnical Commission, National Electrical Code, and Canadian Electrical Code requirements for equipment in hazardous locations. Electrical conduit seal condition data from a 30-year-old petrochemical facility are provided, to illustrate that the threat of gas migration at a facility is real. The collection of these data was achieved by applying new devices allowing for the removal of the conduit seals. An overview of this application and how it was achieved is provided. The outlook on the future development with equipment rated for hazardous locations to reduce conduit seal requirements is explored.

Assessing the blue-water footprint of an opencast platinum mine in South Africa

South Africa's extensive mineral resources have resulted in mining activities dispersed across the country, playing a critical role in its socio-economic development. In contrast to this abundance of mineral wealth, water resources are generally limited, and vulnerable to environmental impacts from the mining industry. These circumstances make tailored management of water resources in the mining sector essential. To achieve this, detailed information on water use throughout a mine operation as well as an accurate water balance account is required. Blue-water footprints have the potential to contribute to this task as they allow for quantification of direct and indirect water use across the supply chain of a process, while incorporating both spatial extension and temporal duration. As defined by the Water Footprint Network's (WFN) globally acknowledged water footprint assessment methodology, a blue-water footprint is determined by calculating the net consumptive use of water by an operation. According to the WFN, this includes water which is evaporated, incorporated into a product, or lost to outflows which do not return to the same catchment area in the same period.The applicability of this tool in the mining sector has not been fully explored. Therefore, it was decided to investigate the bluewater footprint of a South African platinum mining operation. The results showed that the largest consumption of water in the production of platinum was due to evaporation from the mineral processing plants (36.8%) and the tailings storage facilities (19.4%). To improve its water-use efficiency, measures should be taken by the operation to mitigate evaporative losses. Floating covers can assist in this effort as they reflect a proportion of the incoming solar radiation and act as a physical barrier to the passage of water vapour, both vertically and horizontally.

The Effect of Plasticizers on Mechanical Properties and Water Vapor Permeability of Gelatin-Based Edible Films Containing Clay Nanoparticles

The effects of glycerol and sorbitol as two plasticizers on mechanical properties, water vapor permeability, thermal properties, color and capability of heat sealing of gelatin films (of phytophagous fish, bovine gelatin with high gel-forming ability, and bovine gelatin with low gel-forming ability) containing clay nanoparticles were studied in this research. For this purpose, 6 × 2 × 3 factorial experiments using the completely randomized design and comparison of the means at 95% confidence level (α = 0.05) were performed. Higher concentrations of plasticizers increased percentage elongation to the breaking point. When glycerol concentration was raised to over 20%, flexibility of the layers improved but their water vapor permeability increased. The minimum passage of water vapor was that of fish-skin gelatin films containing clay nanoparticles and 30% sorbitol, and the maximum that of bovine gelatin films with high gel-forming ability which contained nanoparticles but no plasticizers (p 0.05). All samples had heat sealing capability, and fish-skin gelatin films containing clay nanoparticles had better heat sealing capability compared with the other samples so that fish-skin gelatin films containing clay nanoparticles with 25% glycerol and 5% sorbitol had the highest flexibility and tensile strength, and remained attached to where they were heat sealed. Electron microscope images showed that films without plasticizers had uniform surfaces, but that samples containing glycerol at concentrations of over 0.20 g/g gelatin exhibited cavities between gelatin chains and that water vapor permeability in gelatin films containing clay nanoparticles.

Mixture design applied to evaluating the effects of polyvinyl alcohol (PVOH) and alginate on the properties of starch‐based films

Mixtures of starch and other polymers have been used to produce biodegradable materials with low‐cost and enhanced properties. In this study, films containing starch mixed with alginate (ALG) and/or polyvinyl alcohol (PVOH) were characterized. Films produced using binary starch–alginate mixtures (F3, F5, and F9) had the highest tensile strength (19–28 MPa) and elongation capacity (22–17%). However, films produced using ternary starch–alginate–PVOH mixtures (F8 and F9) exhibited the best water‐barrier efficacy, with lower water‐vapor permeability (WVP) values (5 × 10 and 5.56 × 10−13 g/s/Pa/m1, respectively) than that of the starch films (23.60 × 10−13 g/s/Pa) and diffusion coefficient (Dw) values approximately seven times lower than that of films produced solely with starch. The results of the infrared analyses showed a decrease in the band representing OH stretching in films created using ternary starch–alginate–PVOH mixtures, suggesting interaction between the polymers. The films containing starch mixed with ALG and PVOH showed low monolayer. The results indicated that ternary blends created better physical barriers to the passage of water vapor and diminished the availability of active sites for water binding. The optimal proportions were found to be 80% starch, 11.4% ALG and 8.6% PVOH.

Si Vapor Chamber Integrated with Through Silicon Via for 3D Packaging

We demonstrate an etched silicon vapor chamber integrated with a through-silicon via (TSV) for 3D packaging. The Si vapor chamber chip enables low mismatch in the thermal expansion coefficient of a Si-LSI chip and provides a new heat dissipation path for 3D-LSI inter layer cooling. For the first prototype of the vapor chamber, an outside 33-mm × 33-mm chip consisting of a 25-mm × 25-mm area for the vapor chamber, a wick structure 30-μm high, and a vapor passage 100-μm high is developed. In-situ observation of the behavior of the working fluid through the cover glass and heat transfer enhancement is successfully demonstrated. The improvement rate of thermal resistance is 7.1% compared to a test chip without working fluid. Next, the fluid flow of a second vapor chamber prototype consisting of the first prototype integrated with a TSV structure using a Si pillar of 150-μm diameter is investigated. Thermal resistance and droplet observation conducted to evaluate the influence of the TSV. The operation of the vapor chamber is confirmed when a Si pillar is arranged to a coarse pitch of more than 500 μm. A droplet is generated and the vapor passage is partially obstructed. However, the droplet eventually degenerated and the performance of the vapor chamber is maintained. When the Si pillar is arranged to a fine pitch of 200 μm, the entire vapor passage is blocked during the liquid charging process, and no improvement is observed in the thermal resistance of the chip.

Diagnostic Study of a Severe Thunderstorm over Jeddah

Several aspects of the interaction between midlatitude and subtropical systems are investigated using a case study and a potential vorticity (PV) framework. Our case study occurred on 25 November 2009; Jeddah and other regions in Western Saudi Arabia were hit by heavy rainstorms. The analysis of absolute, relative, and potential vorticity implies the significance of the lower level dynamics in the initiation of this case of cyclogenesis. The impact of the severe convective weather process caused more than 90 millimeters of rain to fall in Jeddah in just four hours. The analysis indicates that the heavy rainfall was due to the existence of an upper level cold trough in the Eastern Mediterranean and a warm blocking high situated over southeasternSaudi Arabiaand theArabian Sea. In addition, an evident low level shear line set up in the northwest of Jeddah, and the southeast movement of the shear line caused dynamic lifting and unstable energy release over Jeddah. The water vapor transport occurred primarily below 700 hPa, and a low level jet transported the water vapor from the Red Sea to centralSaudi Arabia. Furthermore, the blocking high in southernSaudi Arabiawas favorable for maintaining water vapor passage for a long time. The topography of Jeddah also played a role in the enhancement of convection.

Permeability Measurement of some Barrier Materials as a Function of Temperature and Pressure

Barrier materials possess the ability to restrict the passage of gases, vapors, and organic liquids through their boundaries. These barrier materials have large number of applications in industry and scientific research. To measure the permeability of barrier materials, a specific gas flow system has been developed, pure helium gas is used to measure the back ground reading through SS-316. The permeability and break-through time has been measured through Inconel X-750, NBR and Viton below and above the atmospheric pressure and at different temperatures 20°C, 40°C and 70°C.

Effect of Plasma Etching on Destructive Adsorption Properties of Polypropylene Fibers Containing Magnesium Oxide Nanoparticles

Dermal absorption of pesticides poses a danger for agricultural workers. Use of personal protection equipment (PPE) is required to provide protection; some of the current PPE involves impermeable barriers. In these barrier materials, the same mechanism that prevents the penetration of toxic chemicals also blocks the passage of water vapor and air from flowing through the material, making the garments uncomfortable. Fibers that degrade organophosphate pesticides, such as methyl parathion, were developed by incorporating metal oxides. These modified fibers can be incorporated into conventional fabric structures that allow water vapor to pass through, thereby maintaining comfort. Fibers with self-decontamination functionality were developed by incorporating magnesium oxide (MgO) nanoparticles into a polypropylene (PP) melt-extruded fiber. These fibers were then treated with plasma etching to expose increased surface area of the MgO nanoparticles. Three steps were involved in this research project: (1) determining the reactivity of MgO and methyl parathion, (2) making melt-spun MgO/PP fibers, and (3) testing the reactivity of MgO/PP composite fibers and methyl parathion. It was confirmed that MgO stoichiometrically degrades methyl parathion by way of destructive adsorption. The etching of the PP fibers containing MgO nanoparticles increased the chemical accessibility of MgO reactive sites, therefore making them more effective in degrading methyl parathion. These fibers can enhance the protection provided by PPE to agricultural and horticultural workers and military personnel.

Thin-layer chromatography of polar and ionic compounds using active gas flow over the silica gel adsorbent layer

Separation of polar and ionic substances in carbon dioxide and ammonia atmospheres on unmodified silica gel TLC plates with reduced moisture content has been studied by single and multiple development chromatography with countercurrent drying. Regulation of moisture content and of saturation of the layer with mobile phase vapor, creation of active atmospheres, and countercurrent drying of the mobile phase was achieved by flow of gas over the adsorbent layer. The possibility of simple gradient separation by passage of polar vapor is also shown.

A new modification of the sample introduction system for Os isotope ratio measurements

Here we present a new modification of the sample introduction system aimed at precisely measuring Os isotope ratios. A small glass connector was used to transfer OsO4 vapor from a Carius tube into a nebulizer. After dissolution of sample in a Carius tube, Os isotopes in the sample were determined simultaneously through in situdistillation without any prior separation procedure. The analytical precision at intermediate precision conditions of measurement was improved through the simultaneous introduction of Os via sparging and the aspiration of a solution containing Ir for mass bias correction. The present method, which involves the passage of Os vapor directly into the ICP-MS torch, thus solves the problems encountered previously when optimizing an instrument. The dating results of reference materials (RMs) HLP and JDC by the modified method are 221.8 ± 0.70 Ma (0.31%, 2s, n = 7) and 140.0 ± 0.44 Ma (0.31%, 2s, n = 9) respectively, which are consistent with their certified values of 221.4 ± 5.6 Ma and 139.6 ± 3.8 Ma respectively. Also reported in this study are dating results of several unknown molybdenite samples by the new method.

Membrane distillation heat transfer enhancement by CFD analysis of internal module geometry

Module geometry optimisation can be a crucial matter in all separation processes using selective or hydrophobic membranes, e.g. reverse osmosis (RO) and membrane distillation (MD). In fact the choice of suitable channel shape and size can dramatically affect the performance of the process. With reference to the membrane distillation process, temperature polarization phenomena and pres¬sure drops along the channels largely affect the process efficiency (i.e. the efficient use of temperature driving force for the passage of vapour through the membrane) as well as pressure distribution, module mechanical resistance and pumping costs. Several works have been presented so far in literature on the fluid flow characterization of spacer-filled channels for the case of reverse osmosis modules, but only few works deal with the problem of MD modules optimization. The present work aims at the CFD simulation of the fluid flow and temperature fields within spacer-filled MD module channels for a variety of spacer geomet...

Combustion characteristics of Mg vapor jet flames in CO 2 atmospheres

An experimental study was performed on the combustion characteristics of a jet diffusion flame of Mg vapor injected through a small nozzle into CO 2 atmospheres at low pressures from 8 to 48 kPa with a view to using Mg as fuel for a CO 2-breathing turbojet engine in the Mars atmosphere. The Mg vapor jet produced three types of the flame. At lower pressures and higher injection velocities, a red-heated jet flame formed, in which the injected Mg vapor was heated by spontaneous reactions, turning red. At medium pressures and injection velocities, a stable luminous lifted-like flame developed above the rim of the chimney, a tube-like combustion product for the Mg vapor passage that grew on the nozzle during combustion. The flame had similar flame length properties to laminar jet diffusion flames of gaseous fuels. At higher pressures and lower injection velocities, a stable luminous attached flame developed at the rim of the chimney. The same reactions, producing MgO(g), CO and MgO(c), proceeded preferentially for all flames and chimneys. Carbon was only subordinately generated. Burning behavior of Mg vapor jets in a CO 2 atmosphere has been represented, including the homogeneous reaction of Mg vapor with CO 2, the diffusion of CO 2, and the condensation and deposit of MgO. The injection velocity of Mg vapor at the rim of the chimney and the exothermic reactions with diffused CO 2 that occur there play a crucial role in the attachment and development of the flames. The flame structure may be explained in terms of the relatively low gas-phase reaction rate of Mg with CO 2.

Variations of δ18O in precipitation along vapor transport paths

Three sampling cross sections along the south path starting from the Tropics through the vapor passage in the Yunnan-Guizhou Plateau to the middle-low reaches of the Yangtze River, the north path from West China, via North China, to Japan under the westerlies, and the plateau path from South Asia over the Himalayas to the northern Tibetan Plateau, are set up, based on the IAEA (International Atomic Energy Agency)/WMO global survey network and sampling sites on the Tibetan Plateau. The variations, and the relationship with precipitation and temperature, of the δ18O in precipitation along the three cross sections are analyzed and compared. Along the south path, the seasonal differences of mean δ18O in precipitation are small at the stations located in the Tropics, but increase markedly from Bangkok towards the north, with the δ18O in the rainy season smaller than in the dry season. The δ18O values in precipitation fluctuate on the whole, which shows that there are different vapor sources. Along the north path, the seasonal differences of the mean δ18O in precipitation for the stations in the west of Zhengzhou are all greater than in the east of Zhengzhou. During the cold half of the year, the mean δ18O in precipitation reaches its minimum at Urumqi with the lowest temperature due to the wide, cold high pressure over Mongolia, then increases gradually with longitude, and remains at roughly the same level at the stations eastward from Zhengzhou. During the warm half of the year, the δ18O values in precipitation are lower in the east than in the west, markedly influenced by the summer monsoon over East Asia. Along the plateau path, the mean δ18O values in precipitation in the rainy season are correspondingly high in the southern parts of the Indian subcontinent, and then decrease gradually with latitude. A sharp depletion of the stable isotopic compositions in precipitation takes place due to the very strong rainout of the stable isotopic compositions in vapor in the process of lifting over the southern slope of the Himalayas. The low level of the δ18O in precipitation is from Nyalam to the Tanggula Mountains during the rainy season, but δ18O increases persistently with increasing latitude from the Tanggula Mountains to the northern Tibetan Plateau because of the replenishment of vapor with relatively heavy stable isotopic compositions originating from the inner plateau. During the dry season, the mean δ18O values in precipitation basically decrease along the path from the south to the north. Generally, the mean δ18O in precipitation during the rainy season is lower than in the dry season for the regions controlled by the monsoons over South Asia or the plateau, and opposite for the regions without a monsoon or with a weak monsoon.

Atmospheric hydrological budget with its effects over Tibetan Plateau

Based on 1961–2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a “vapor transition belt”, vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient −0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5°–32.5°N) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas.

Constraints on 2-Way Transport across the Arctic Tropopause Based on O3, Stratospheric Tracer (SF6) Ages, and Water Vapor Isotope (D, T) Tracers

Based upon airborne trace gas and isotope observations in the winter months 1991/1992 to1994/1995, transport pathways across the mid-latitude and Arctic tropopause areinvestigated. A powerful set of contrasting transport tracers are examined, such asdeuterated water vapor (HDO) which is shown to trace the passage of water vapor from thetroposphere into the lowermost stratosphere (LS), or the `SF6 age' defined as theresidence time of an air parcel within the stratosphere since its entry at thetropopause. Cross-tropopause transport in both directions was found near mid-latitudecyclones (at baroclinic flanks of troughs in the polar front), in which about 80% of thestratosphere-to-troposphere flux proceeded along potential temperature (θ)surfaces of 300 ± 10 K. As these isentropes are the lowest which reach into the LS(in winter), a mixing zone just above the Arctic tropopause (at least 1.5 km thick) isformed. Here, upwelling tropospheric air is mixed with downwelling LS air which isaffected by air from higher altitudes, the surf-zone and the polar vortex. The observedelevated D/H isotope ratio of water vapor within the mixing zone can be explained byinjection of subtropical water vapor that is transported to the tropopause by the warmconveyor belt associated with mid-latitude cyclones. Downward vertical transport ofArctic LS air, which may be influenced by ouflowing chemically disturbed polar vortexair, into the Arctic troposphere was found to be small.

Scanning electron microscopy of the respiratory epithelium of chicks fumigated with formaldehyde vapour.

1. Hatching chicks were exposed to 10.9 ppm of formaldehyde vapour during the last 3 d of incubation in a commercial situation. 2. Samples from pre-selected regions of the entire respiratory tract, taken at 0, 6, 30 and 54 h post-vaporisation of formaldehyde, were examined by scanning electron microscopy for surface morphological features and associated pathological changes. 3. Clumping of cilia, blebs on the cilial wall, deciliation and exfoliation of the epithelium were all observed under the scanning electron microscope. 4. Lesions were more severe in chicks exposed for 54 h as compared to those exposed for 6 and 30 h. There were no regional differences in the lesions throughout the respiratory tract of all the chicks. 5. Limited observations suggest that the passage of formaldehyde vapour across the egg shell wall may influence the morphology of the respiratory lining of the developing embryo.