Residual Vapor Research Articles

X-ray photoelectron spectroscopy and conducting atomic force microscopy investigations on dual ion beam sputtered MgO ultrathin films

Abstract Ultrathin films of MgO (~ 6 nm) were deposited on Si(100) using dual ion beam sputtering in different partial pressures of oxygen. These thin films were characterized by X-ray photoelectron spectroscopy (XPS) for chemical state analysis and conducting atomic force microscopy for topography and local conductivity map. No trace of metal Mg was evidenced in these MgO films. The XPS analysis clearly brought out the formation of oxygen interstitials and Mg(OH) 2 primarily due to the presence of residual water vapors in the chamber. An optimum value of oxygen partial pressure of ~ 4.4 × 10 − 2 Pa is identified with regard to homogeneity of film and stoichiometry across the film thickness (O:Mg::0.93–0.97). The local conductivity mapping investigations also established the film homogeneity in respect of electrical resistivity. Non-linear local current–voltage curves revealed typical tunneling characteristics with barrier width of ~ 5.6 nm and barrier height of ~ 0.92 eV.

Thermodynamics of an idealized hydrologic cycle

The diurnal hydrologic cycle, a sequence of evapotranspiration, boundary layer growth, moist convection, and precipitation, is described in a thermodynamic framework, assuming an atmosphere composed solely of water. This idealized cycle is shown to be equivalent to an abbreviated version of the classical Rankine cycle where not all the water vapor is condensed. Energy and entropy fluxes of the processes involved in the cycle are quantified using the reversible approximation as a function of the quality of the liquid‐vapor mixture (the ratio of the residual background vapor and the total mass of water) and the different temperatures at which evaporation and condensation take place. The proposed framework allows quantitative estimates of the net work (which is used by the cycle to drive the atmospheric circulation and dissipated by various frictional forces and nonidealities) as well as of the thermodynamic efficiency of the cycle. Possible extensions of the idealized framework relating to the role of dry air and the inclusion of various irreversible processes are also discussed.

Development of Composite Adsorbents of Activated Carbon and Hydrophobic Silica Gel for Gasoline Vapor Adsorption

A composite adsorbent with upper-layer activated carbon (TY) and lower-layer hydrophobic silica gel (HSG) was developed, based on the comprehensive consideration of both adsorption capacity and adsorption heat of activated carbon and hydrophobic silica. For the composite adsorbent, various volumetric ratio of activated carbon to silica gel was designed, and the adsorption capacity and heat effect of the composite adsorbent with different ratio were investigated. The experimental results showed that the optimum ratio was 1:1. Thus, the vapor with high concentration was early adsorbed by the lower-layer hydrophobic silica gel, and then the residual vapor with low concentration was late adsorbed by the upper-layer activated carbon. In this way, incombustibility of silica gel and high adsorption capacity of activated carbon were fully utilized; accordingly the adsorption operation safety was improved and the adsorption capacity of activated carbon was increased owing to that the activated carbon was only used to adsorb the vapor with low concentration.

The Effect of Dryer Load on Freeze Drying Process Design

Freeze-drying using a partial load is a common occurrence during the early manufacturing stages when insufficient amounts of active pharmaceutical ingredient (API) are available. In such cases, the immediate production needs are met by performing lyophilization with less than a full freeze dryer load. However, it is not obvious at what fractional load significant deviations from full load behavior begin. The objective of this research was to systematically study the effects of variation in product load on freeze drying behavior in laboratory, pilot and clinical scale freeze-dryers. Experiments were conducted with 5% mannitol (high heat and mass flux) and 5% sucrose (low heat and mass flux) at different product loads (100%, 50%, 10%, and 2%). Product temperature was measured in edge as well as center vials with thermocouples. Specific surface area (SSA) was measured by BET gas adsorption analysis and residual moisture was measured by Karl Fischer. In the lab scale freeze-dryer, the molar flux of inert gas was determined by direct flow measurement using a flowmeter and the molar flux of water vapor was determined by manometric temperature measurement (MTM) and tunable diode laser absorption spectroscopy (TDLAS) techniques. Comparative pressure measurement (capacitance manometer vs. Pirani) was used to determine primary drying time. For both 5% mannitol and 5% sucrose, primary drying time decreases and product temperature increases as the load on the shelves decreases. No systematic variation was observed in residual moisture and vapor composition as load decreased. Further, SSA data suggests that there are no significant freezing differences under different load conditions. Independent of dryer scale, among all the effects, variation in radiation heat transfer from the chamber walls to the product seems to be the dominant effect resulting in shorter primary drying time as the load on the shelf decreases (i.e., the fraction of edge vials increases).

Thermogravimetry and vapor pressure moisture

Thermogravimetry (TG), thermogravimetry/mass spectrometry (TG/MS), and loss-on-drying methodology are used to provide residual moisture results for freeze-dried biological products regulated by the US Food and Drug Administration. Residual moisture specifications must be met in order to ensure freeze-dried biological product potency and stability throughout the licensed product's shelf life. TG, TG/MS, loss-on-drying and vapor pressure moisture measurements are compared for a BCG Vaccine. Comparisons are made between residual moisture data for the freeze-dried cake and vapor pressure moisture determinations in the space above the freeze-dried cake in the final container. Vapor pressure moisture precision data is presented for α-interferon and BCG vaccine. Impact of residual moisture and vapor pressure moisture upon product stability is presented.

Geology and Genesis of the Multistage High-Sulfidation Epithermal Pascua Au-Ag-Cu Deposit, Chile and Argentina

The giant Pascua epithermal Au-Ag-Cu deposit is located in the El Indio belt of north-central Chile and Argentina and was the product of a high-sulfidation hydrothermal system. The host rocks consist mainly of Triassic granite and heterolithic Miocene breccia pipes. Granitic rocks host ~60 percent of the mineralization (or >80% if granitic breccia fragments are included) but were not the cause of hydrothermal activity. The economic mineralization forms a large orebody centered on Brecha Central, the largest of the breccia pipes, and several smaller satellite bodies that are separated by zones of subeconomic mineralization. Hydrothermal activity produced two main stages of advanced argillic and vuggy silica alteration. These were separated by an intermediate stage of argillic alteration, silicification and hypogene jarosite, which occurred penecontemporaneously with the emplacement of Brecha Central. Main-stage Au-Ag-Cu mineralization occurred toward the end of the second stage of alteration and involved precipitation of native gold with pyrite and enargite and incorporation of Au in the structure of these minerals. Four types of mineralization are recognized based on the occurrence of economic concentrations of Au in rocks containing significant amounts of the following minerals: (1) alunite, pyrite, and enargite; (2) pyrite; (3) pyrite and szomolnokite; and (4) native gold. Main-stage gold mineralization was followed by a sulfate stage represented by barite and anglesite at lower elevations and barite, anglesite, plus primary szomolnokite, the first reported occurrence of this phase as a hydrothermal ore mineral, at higher elevations. Late-stage silver mineralization, characterized by the occurrence of microscopic Cl-, I-, and Hg-bearing phases in voids and fractures, enriched the upper parts of the deposit, forming an extensive subhorizontal zone that overprints previous alteration and mineralization. Advanced argillic alteration and high-sulfidation mineralization at Pascua are interpreted to have resulted from a high-level hydrothermal system developed above a porphyry stock located in Argentina. Extensive vuggy silica and advanced argillic alteration reflect interaction of the wall rocks with acidic magmatic vapors. Gold, copper, and arsenic are interpreted to have been transported by these vapors and to have deposited as a result of their cooling and subsequent condensation. Ore-forming hydrothermal activity terminated with silver enrichment in response to the condensation of residual magmatic vapors during the waning stages of the system.

Cultivation of the Dible Mushroom Lentinula edodes (Shiitake) in Pasteurized Wheat Straw – Alternative Use of Georthermal Energy in Mexico

AbstractFive edible Lentinula edodes strains were evaluated. The mushrooms were cultivated on a wheat straw substrate that was previously pasteurized by immersion in water heated by residual geothermal vapor, which was also used to warm incubation and production rooms. Finely chopped wheat straw (Triticum aestivum L.) was pasteurized and then spawned with supplemented spawn capable of supplying nutrients and enriching the substrate, with the expectation of yield improvement. The samples were incubated for 60 days before the production started and thus, the mushrooms produced had pileus diameters ranging from 5 to 20 cm. The yields fluctuated from 6.2 to 13.9 % (fresh weight of mushrooms/fresh weight of substrate). Biological efficiency ranged from 24.8 to 55.6 % (fresh weight of mushrooms/dry weight of substrate), while the production rate reached varied from 0.19 to 0.55 % (biological efficiency/production time starting from inoculation).The cultivation system evaluated here offers the possibility of lowering production costs by cultivating the mushroom on easily obtainable substrate and shortening the culture cycle. The efficiency of this use of geothermal energy and supplemented spawn for shiitake mushroom cultivation on non‐sterilized substrates was proven.

Surface properties and biocompatibility of solvent-cast poly[ ε-caprolactone] films

Poly(epsilon-caprolactone) (PCL) was dissolved in four solvent systems, chloroform, tetrahydrofuran, acetone and ethyl acetate, and cast onto glass Petri dishes. The surface properties of the resulting films were investigated. The extent to which their properties were determined by the solvent used in each case was quantified in terms of contact angle, surface morphology, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and the adhesion and proliferation of fibroblasts by direct contact. The surface of the PCL film in contact with glass was denoted the SG surface, and the other, which was exposed to the gas phase, a mixture of air and residual solvent vapour, was denoted the SA surface. In the case of hydrophobic solvent systems, the advancing contact angle of the SG surface was always lower than that of the SA surface. With hydrophilic solvent systems, on the other hand, the advancing contact angle of the SG film surface was higher when the contact angle of the Petri dish was higher than that of the gaseous mixture of the air and solvent vapour, otherwise it was lower or equal to that of the surface on which it was cast. The surface morphology was dictated by the solubility of PCL in the respective solvent systems: high dissolution solvents such as chloroform and tetrahydrofuran produced films that comprised PCL aggregates, the particles being larger in the case of chloroform, whereas the less efficient solvents (acetone and ethyl acetate) resulted in a filamentous structure. The ATR-FTIR results confirmed that the chemistry of the SA surfaces differed according to the solvent system used. Preliminary cell culture experiments carried out with the PCL films established that murine (L929) fibroblasts grew well on all surfaces regardless of the solvent used, although the rates of adhesion and proliferation were not as great as on tissue culture plastic controls. Of all the surfaces examined in this study, the cells favoured the SG aspect of ethyl acetate cast PCL films, the surface of which had the finest pore size and relatively low contact angle.

Flying Metal Pipe for Target Transport in Inertial Fusion Energy Reactor

The flow of residual metal vapor in an inertial fusion energy (IFE) reactor chamber causes (a) forced convection heat transport to the target, (b) drag force to the target, and (c) deviation of the orbit of the target. To solve these difficulties, a flying metal pipe concept for target transport in an IFE reactor is proposed.The metal pipe is composed of material identical to the liquid metal used in the IFE reactor. The metal pipe (typically 0.5-cm radius and 2-m length) is injected from the top of the IFE reactor chamber. Subsequently, the IFE target is injected, and it goes into the metal pipe, goes out from the other side of the pipe, and arrives at the center of the IFE reactor chamber to be shot by energy beams. The target in the pipe is protected against radiation, forced convection heat from residual gas, and the wind in the IFE reactor chamber. In the case that the flying metal pipe is used in the reactor, heat transport to the target and deviation of the orbit of the target decrease. After microexplosion of the IFE target, the metal pipe arrives at the bottom of the reactor chamber and melts in the liquid-metal pool.

Piecewise linear model for water column oscillator simulating reactor safety system

A water column oscillation system, which is simulating the pressure balanced injection system in an advanced nuclear power plant, consists of free surfaces in a main-tank and a sub-tank. A cover gas simulating residual heat vapor generation is injected into the main-tank constantly and ejected intermittently. The water level can be described by a set of two piecewise linear ordinary differential equations with four independent parameters. The solution shows chaotic features under specific conditions. The behavior and bifurcation are examined.

Formation of large metal nodules in ordinary chondrites

Literature data show that many large (2–30 mm) metallic Fe‐Ni nodules in ordinary chondrites are depleted in refractory siderophiles (e.g., Re, Os, Ir, Ru, Pt, and Rh) and Cu relative to fine‐grained metal but are not depleted in (normally refractory) W and Mo, common siderophiles (e.g., Ni and Co) and volatile siderophiles (e.g., Au, As, and Sb). It was recently proposed that metamorphic diffusion could form the metal nodules and that partitioning of siderophile elements between kamacite and taenite could account for the nodules' unusual compositions. However, the nodules have the same compositional trends as metal nodules and veins in shocked meteorites that clearly formed by impact‐related processes. If large metal nodules formed during metamorphism, type 6 chondrites should contain abundant large nodules. Instead, the mean metal grain size in H6 chondrites is 0.12±0.15 mm, far smaller than any of the nodules. It seems likely that the metal nodules formed by impact vaporization, oxidation of W and Mo to form volatile oxides, concomitant partial oxidation of Re and Os, rapid fractional condensation of refractory siderophiles, transport of the residual vapor, condensation of Cu, S, and Se into vugs and fractures to form sulfide, and condensation of the remaining siderophiles to form metal nodules and veins. During vapor cooling and condensation (or during subsequent parent body annealing) W, Mo, Re, and Os oxides were reduced.

Instabilities of prebreakdown currents in vacuum I: late breakdowns

Prebreakdown electron emission between extended metal electrodes is experimentally studied with time resolution of 100 ns. Switching to higher emission levels is observed and could be provoked by mechanical shocks. This is found to be analogous to spontaneous switching effects. Elementary time constants of current jumps are 1-3 µs while the whole switching process lasts up to 40 ms, thus ruling out impact of macroparticles. The breakdown voltage is found to be correlated with the emission level. Therefore, switching on electron emission can explain breakdowns with delay times >1 ms. Still longer times are found at the deposition of metal vapour plasma originating from neighbouring arc gaps. In some cases, transient increases of the emission occur that last several seconds. Therefore, in vacuum interrupters late breakdowns after current zero can be caused by mechanical shocks without particle impact and also by deposition of residual vapour at the cathode.

Development of a Packed Precolumn for Capillary Gas Chromatographic Analysis of Amines in Acidic Aqueous Solution

This paper describes an optimization of the analysis of amines in aqueous solution. Direct injection of the acidic sample (HCl 0.12 N) is performed by the coupling of packed precolumn with a capillary column. The basic support efficiently traps residual vapors of hydrochloric acid and water at the injection time; the capillary chromatographic performance is maintained. The precolumn coupling with PoraPLOT Amines capillary column enables a separation and quantification of the lower volatile aliphatic amines (methylamine, dimethylamine, trimethylamine and ethylamine). The ammonia addition to the solution (200 ppm NH3) reduces amine adsorption in the column. The analysis repeatability is about 5% for a 50μM amine mixture and 21% for the quantification limit of 0.5 μM with a sensitive and specific nitrogen phosphor detector. The precolumn avoids using split injection (sensitivity increased). Other nitrogen compounds can be analyzed by this system: aromatic amines (aniline) and unsaturated nitrogen heterocycles (pyridine). This new technique increases the chromatographic performances in comparison with usual methods; its automation is possible.

Development of a packed precolumn for capillary gas chromatographic analysis of amines in acidic aqueous solution

This paper describes an optimization of the analysis of amines in aqueous solution. Direct injection of the acidic sample (HCl 0.12 N) is performed by the coupling of packed precolumn with a capillary column. The basic support efficiently traps residual vapors of hydrochloric acid and water at the injection time; the capillary chromatographic performance is maintained. The precolumn coupling with PoraPLOT Amines capillary column enables a separation and quantification of the lower volatile aliphatic amines (methylamine, dimethylamine, trimethylamine and ethylamine). The ammonia addition to the solution (200 ppm NH 3 ) reduces amine adsorption in the column. The analysis repeatability is about 5% for a 50μM amine mixture and 21% for the quantification limit of 0.5 μM with a sensitive and specific nitrogen phosphor detector. The precolumn avoids using split injection (sensitivity increased). Other nitrogen compounds can be analyzed by this system: aromatic amines (aniline) and unsaturated nitrogen heterocycles (pyridine). This new technique increases the chromatographic performances in comparison with usual methods; its automation is possible.

Development of microbial mercury detoxification processes using mercury-hyperresistant strain ofPseudomonas aeruginosa PU21

A mercury-hyperresistant strain of Pseudomonas aeruginosa PU21 harboring plasmid Rip64 was utilized to develop bioprocesses able to detoxify and recover soluble mercuric ions in aquatic systems. The kinetics of mercury detoxification was investigated to determine the parameters needed for the design of the bioprocesses. Batch, fed-batch, and continuous bioreactors were utilized to evaluate the efficiency and feasibility of each mode of operation. The results showed that the specific mercury detoxification rate was dependent on cell growth phases, as well as the initial mercury concentrations. Cells at the lag growth phase exhibited the best specific detoxification rate of approximately 1.1 x 10(-6) microg Hg/cell/h, and the rate was optimal at an initial mercury concentration of 8 mg/L. In batch operations with initial mercuric ions ranging from 2 to 10 mg/L, the mercuric ions added were rapidly volatilized from the media in less than 2-3 h. With periodic feeding of 3 or 5 mg Hg/L at fixed time intervals, the fed-batch processes had mercury removal efficiencies of 2.9 and 3.3 mg Hg/h/L, respectively. For continuous operations, the effluent cell concentration (Xe) was essentially invariant at 527 and 523 mg/L with the dilution rates (D) of 0.18 and 0.325 h-1, respectively. The increase in mercury feeding concentrations (Hgf) from 1.0 to 6.15 mg Hg2+/L did not affect the steady-state cell concentration (Xe) but forced the effluent mercury concentration (Hge) to increase. The decrease in the dilution rate, however, resulted in lower Hge values. It was also found that sequential mercury vapor absorption columns recovered over 80% of the Hg degrees released from the bioreactor while the residual mercury vapor was subsequently immobilized by an activated carbon trap in the down stream of the absorption column.

Simultaneous determination of phenylureas and triazines in water, by capillary gas chromatography with ion trap detection and large volume injection

A GC method is described for the simultaneous determination of triazines and phenylureas in aqueous samples by large volume injection with a Programmable Temperature Vaporisator injector (PTV) and ion trap detection (ITD). The analytical col- umn (DB 5MS, 30 m, 0.25 mm, 0.25 μm) is connected to a pre-column (DB 5MS, 5 m, 0.25 mm, 0.25 μm) via a cross piece valve (MCS) to prevent residual solvant vapour from polluting the analytical column. The 8 pesticides (4 triazines and 4 ureas) are determined by this method, the linearity is improved using 2 Fisher test. The detection and the quantification limits are a lso determined for each compounds and are less than 0.10 μg/L which is the limit fixed by the ECC reglementation on drinking water.

Effects of As cell temperature on oval defect density and C acceptor concentration of light Si-doped GaAs grown by molecular beam epitaxy

We report the correlation between As effusion cell temperature and residual CO vapor intensity, oval defect density, C acceptor concentration and electrical properties of GaAs layers grown by molecular beam epitaxy. The As cell is found to be one of the sources of CO vapor. The oval defect density on GaAs surfaces and C acceptors incorporated into the material are directly proportional to the residual CO vapor intensity. We suggest that the reaction between Ga and CO vapor on the hot Ga cell surface may be responsible for the formation of oval defects, and the C generated from this reaction may enhance C acceptor concentration of the grown GaAs material.

A Portable Local Exhaust Hood System Used to Sample One-Ton Containers Previously Filled with Chemical Warfare Munitions

Abstract The Tennessee Valley Authority (TVA), Muscle Shoals, Alabama, by contract with the Department of the Army, Rocky Mountain Arsenal (RMA), Denver, Colorado, sampled and verified the decontamination level of 2354 empty one-ton containers (TCs) previously used to store chemical warfare munitions. The TCs had previously been chemically and/or thermally decontaminated and were stored at RMA awaiting removal and disposal. The size and weight of the TCs prohibited placing them inside an enclosure during sampling. To enable sampling containers in place, a portable local exhaust hood was devised to protect sampling personnel and to prevent the release of any residual chemical agent vapors to the environment. Agent vapors captured by the hood were scrubbed through a 200-lb bed of activated charcoal before being released to the ambient environment. Engineers and work crews on site in Denver conceived the hood design and tested three prototypes before obtaining a functional unit. Craftspersons in Muscle Shoal...

Fractionation of refractory siderophile elements in metal from the Rose City meteorite

Abstract— An ∼4 × 9 × 12‐mm concentration of metal (dubbed RC1) situated between silicate melt and a relict chondritic clast in the Rose City H5 impact‐melt breccia is compositionally heterogeneous. Approximately 65 wt% of RC1 is enriched in the refractory siderophile elements, Os and Ir, by 30–40% relative to bulk H chondrite metal; ∼20 wt% is depleted in these elements by 31–35%; and 15 wt% is depleted by a considerably greater amount (75%). Common and volatile siderophile elements are essentially unfractionated in all three regions; W is fractionated to only a moderate degree. The compositions of the different regions of RC1 are similar to those of previously analyzed metal nodules and veins in shocked but unmelted ordinary chondrites. All of these objects probably formed by a complex process involving vaporization of chondritic material, rapidly followed by oxidation of W to form volatile oxides, fractional condensation of refractory siderophile elements, transport of the residual vapor (containing common and volatile siderophile elements as well as W oxide) and condensation of this vapor in fractures and voids or on metallic liquid substrates. The common occurrence of vugs in shock‐heated chondrites and the pervasiveness of vaporization effects recorded in metal masses and veins underscores the important role of superheating in the formation of impact breccias.

Determination in Situ of Chemical Solvent Vapors in a Semiconductor Workplace with an Open Path FTIR Spectrometer

AbstractAn FTIR spectrometer having a long absorbing path in an open field mode is applied to measure the air quality of semiconductor facilities, especially for chemical solvent vapors. This spectrometer is demonstrated to be a proper instrument to monitor chemical solvents widely used in the manufacture of integrated circuits. By means of the great sensitivity accruing from the kilometer pathlength, we discovered that many residual chemical solvent vapors are released in these workplaces; the limit of detection can attain the level of parts per billion by volume. Recognized spectra of chemical solvents, such as 2‐ethoxyethyl acetate, 2‐propanol, hexamethyl disilazane, aromatic hydrocarbons, alkyl derivatives of phenol, alkyl benzene sulfonate and dimethyl sulfoxide, are calibrated qualitatively and quantitatively. The related integrated absorption coefficients (or band intensities) are listed in this paper. By examining the measured spectra, we found two chemical solvents (2‐propanoI and hexamethyl disilazane) in the workplace, at concentrations about 20‐500 ppbv in such environments.