Oxygen Input Research Articles

Hydrothermal sediments record changes in deep water oxygen content in the SE Pacific

The distribution of redox?sensitive metals in sediments is potentially a proxy for past ocean ventilation and productivity, but deconvolving these two major controls has proved difficult to date. Here we present a 740 kyr long record of trace element concentrations from an archived sediment core collected at ?15°S on the western flank of the East Pacific Rise (EPR) on 1.1 Myr old crust and underlying the largest known hydrothermal plume in the world ocean. The downcore trace element distribution is controlled by a variable diagenetic overprint of the inferred primary hydrothermal plume input. Two main diagenetic processes are operating at this site: redox cycling of transition metals and ferrihydrite to goethite transition during aging. The depth of oxidation in these sediments is controlled by fluctuations in the relative balance of bottom water oxygen and electron donor input (organic matter and hydrothermal sulfides). These fluctuations induce apparent variations in the accumulation of redox?sensitive species with time. Subsurface U and P peaks in glacial age sediments, in this and other published data sets along the southern EPR, indicate that basin?wide changes in deep ocean ventilation, in particular at glacial?interglacial terminations II, III, IV, and V, alter the depth of the oxidation front in the sediments. These basin?wide changes in the deep Pacific have significant implications for carbon partitioning in the ocean?atmosphere system, and the distribution of redox?sensitive metals in ridge crest sediment can be used to reconstruct past ocean conditions at abyssal depths in the absence of alternative proxy records.

Plant species traits regulate methane production in freshwater wetland soils

Ecosystem and biogeochemical responses to anthropogenic stressors are the result of complex interactions between plants and microbes. A mechanistic understanding of how plant traits influence microbial processes is needed in order to predict the ecosystem-level effects of natural or anthropogenic change. This is particularly true in wetland ecosystems, where plants alter the availability of both electron donors (e.g., organic carbon) and electron acceptors (e.g., oxygen and ferric iron), thereby regulating the total amount of anaerobic respiration and the production of methane, a highly potent greenhouse gas. In this study, we examined how plant traits associated with plant inputs of carbon (photosynthesis and biomass) and oxygen (root porosity and ferric iron on roots) to mineral soils relate to microbial competition for organic carbon and, ultimately, methane production. Plant productivity was positively correlated with microbial respiration and negatively correlated to methane production. Root porosity was relatively constant across plant species, but belowground biomass, total biomass, and the concentration of oxidized (ferric) iron on roots varied significantly between species. As a result the size of the total root oxidized iron pool varied considerably across plant species, scaling with plant productivity. Large pools of oxidized iron were related to high CO2:CH4 ratios during microbial respiration, indicating that as plant productivity and biomass increased, microbes used non-methanogenic respiration pathways, most likely including the reduction of iron oxides. Taken together these results suggest that increased oxygen input from plants with greater biomass can offset any potential stimulation of methanogenic microbes from additional carbon inputs. Because the species composition of plant communities influences both electron donor and acceptor availability in wetland soils, changes in plant species as a consequence of anthropogenic disturbance have the potential to trigger profound effects on microbial processes, including changes in anaerobic decomposition rates and the proportion of mineralized carbon emitted as the greenhouse gas methane.

The widespread occurrence of coupled carbonate dissolution/reprecipitation in surface sediments on the Bahamas Bank

Using two complimentary approaches (pore water advection/diffusion/ reaction modeling and stable isotope mass balance calculations) we show that carbonate dissolution/reprecipitation occurs on early diagenetic time scales across a broad range of sediments on the Great Bahamas Bank. The input of oxygen into the sediments, which strongly controls sediment carbonate dissolution, has two major sources—belowground input by seagrasses (that is, seagrass O2 pumping), and permeability-driven advective pore water exchange. The relative importance of these O2 delivery mechanisms depends on both seagrass density, and on how bottom water flow interacts with the seagrass canopy and leads to this advective exchange. Dissolution appears to involve the preferential dissolution of high-Mg calcite, and the rates of dissolution increase linearly with increasing seagrass density. Isotopic evidence of dissolution/reprecipitation is consistent with the occurrence of Ostwald ripening as the mechanism of reprecipitation, in which smaller crystals dissolve and then reprecipitate as larger crystals, with little or no change in mineralogy. Estimates of the aerially-integrated dissolution flux on the Bahamas Bank suggest that carbonate dissolution is an important loss term in the budget of shallow water carbonate sediments, and that on-bank carbonate dissolution, rather than offshore transport, may represent an important sink for gross shallow water carbonate production. Dissolution in carbonate bank and bay sediments may also be a significant alkalinity source to the surface ocean, and should be considered in global alkalinity/carbonate budget. Finally, coupled dissolution/reprecipitation may have a major impact on the stable isotope composition of carbonate sediments that are ultimately preserved in the rock record. These processes may therefore need to be considered, for example, when using carbon isotope records to obtain information on the operation of the global carbon cycle during the Phanerozoic.

Cyclic oxidation and diffusion barrier behaviors of oxides dispersed NiCoCrAlY coatings

NiCoCrAlY has been widely used as the bond coat material in thermal barrier coatings (TBCs). Inter-diffusion between the bond coat and superalloy could degrade the performance of the coating and the mechanical properties of the superalloy. In this paper, oxide dispersed (OD) NiCoCrAlY coatings were deposited onto superalloy DZ 125 using EB-PVD by introducing oxygen during the deposition process. Cyclic oxidation and inter-diffusion behaviors of the coated specimens at 1323 K were investigated. The OD coating deposited with high level oxygen input effectively prevented outward diffusion of the elements such as Hf and W in superalloy. For the conventional NiCoCrAlY coating, Hf migrated to the coating surfaces and caused accelerated thickening and chipping spallation of TGO. The OD coating with high level oxygen input exhibits an improved cyclic oxidation resistance as compared to the conventional NiCoCrAlY coating and the OD coating with lower level of oxygen input.

Modelling waste stabilisation ponds with an extended version of ASM3

In this paper an extended version of IWA's Activated Sludge Model No 3 (ASM3) was developed to simulate processes in waste stabilisation ponds (WSP). The model modifications included the integration of algae biomass and gas transfer processes for oxygen, carbon dioxide and ammonia depending on wind velocity and a simple ionic equilibrium. The model was applied to a pilot-scale WSP system operated in the city of Florianópolis (Brazil). The system was used to treat leachate from a municipal waste landfill. Mean influent concentrations to the facultative pond of 1,456 g(COD)/m(3) and 505 g(NH4-N)/m(3) were measured. Experimental results indicated an ammonia nitrogen removal of 89.5% with negligible rates of nitrification but intensive ammonia stripping to the atmosphere. Measured data was used in the simulations to consider the impact of wind velocity on oxygen input of 11.1 to 14.4 g(O2)/(m(2) d) and sun radiation on photosynthesis. Good results for pH and ammonia removal were achieved with mean stripping rates of 18.2 and 4.5 g(N)/(m(2) d) for the facultative and maturation pond respectively. Based on measured chlorophyll a concentrations and depending on light intensity and TSS concentration it was possible to model algae concentrations.

Modeling and characterization of field-enhanced corona discharge in ozone-generator diode

Electric field enhanced corona plasma discharge in ozone generator diode of axial symmetry has been investigated and characterized in theory. The cathode K of diode is made of a large number of sharpened nozzles arranged on various radial planes on the axial mast and pervaded in oxygen gas inside the anode cup A, produces high fields over MV/m and aids in the formation of a corona plume of dense ozone cloud over the cathode surface. An r-z finite difference scheme has been devised and employed to numerically determine the potential and electric field distributions inside the diode. The analyses of cathode emissions revealed a field emission domain conformed to modified Child-Langmuir diode-current. Passage of higher currents (over μA) in shorter A-K gaps d gave rise to cathode heated plasma extending from the corona to Saha regimes depending on local temperature. Plasma densities of order 102-106 m-3 are predicted in these. For larger d however, currents are smaller and heating negligible and a negative corona favoring ozone formation is attained. High ozone yields about 20 per cent of oxygen input is predicted in this domain. The generator so developed will be applied to various important applications such as, purification of ambient air /drinking water, ozone therapy, and so on.

EFFECTS OF OZONE TREATMENT ON MICROFLORA OF DRIED SAFFRON AND ITS LIVING LARVAE

Saffron is an expensive agricultural and pharmaceutical that has a special position among industrial and commercial products. In these days Iran is the greatest producer and exporter of saffron in the world and more than 65% of the world production of this expensive product is related to Iran. This expensive product of our country, because of the contact with soil, has a high microbial contamination for which especially at the beginning of the season the amount is higher than the permitted standard amount which is in microbial characteristics and test methods according to the national standard of Iran, No. 5689. In addition to that, the existence of larvae in saffron causes difficulties in exporting this valuable product. There are many methods which are recommended for the decontaminating of saffron such as ionization, microwave and fumigation. In this research, ozone was used as a disinfectant for saffron, which was attacked by pests and microorganisms. The aim is to omit or reduce the population of pests and microorganisms without any noticeable damage to the color, flavor and fragrance of saffron. An ozone generator which produced 5 g/h ozone was used. For the purpose of inactivating microbiological contamination of saffron, 4 levels of ozone in 4 times of 0, 1, 2, 3 hours was used. After using these conditions microbiological tests including total count of bacteria, coliform, mold and yeast and chemical analyses of main characteristics of saffron were carried out. The results were analyzed statistically. Moreover the samples were examined for the presence of living larvae, after using 4.7 ppm dosage of ozone. The results of this research showed that in the 4 th level of ozone (input of pure oxygen to the ozone generator was 6 L/min) for 3 hours contact time of saffron with ozone, the number of total count of bacteria, coliform, mold and yeast decreased up to 93.3%, 99.8%, 96.9% and 84.5%, respectively. In the 4 th level of ozone (input of pure oxygen to the ozone generator was 6 L/min) and in 3 hours contact time of saffron with ozone, the results of crocin, saffranal and picrocrosin estimation showed a decrease of 14.9%, 10.46% and 13.85%, respectively. The use of ozone (4.7 ppm) for 20 minutes annihilated almost 84% of larvaes whereas further ozonation exposure (total time 40 min) had as result that nearly no larvaes remained alive.

PFC-Free Dry Etching Method for Si Using Narrow-Gap VHF Plasma at Subatmospheric Pressure

We propose a Si dry etching method that does not require any perfluorocarbon (PFC) source gases with a high global warming potential. This method uses a narrow-gap, very high frequency (VHF) glow plasma of an gas mixture at subatmospheric pressure to generate etchant species (such as fluorine atoms) from the stable solid poly(tetrafluoroethylene) (PTFE) resin. The gas component generated by the chemical reaction between the plasma and PTFE is studied by Fourier transform IR gas analysis. In using a pure He plasma, the generated gases almost consist of PFC molecules. On the contrary, in the mixture plasma, stable gaseous species generated from the PTFE source mainly consist of and . The etching rate of Si depends on both oxygen partial pressure and input electric power . Especially, the Si etching rate is very sensitive to . These results combined with the detailed analysis of optical emission spectra suggest that the oxygen addition suppresses the generation of higher order molecules and increases the etchant species, such as and . A very high Si etching rate of at and has been attained.

Oxidative pre-treatment in thiosulphate leaching of sulphide gold ores

Abstract A diagnostic leaching showed that partial oxidation of the sulphide minerals in a gold ore was beneficial for thiosulphate leaching of gold. A pre-treatment process with oxidative ammoniacal solution enhanced the thiosulphate leaching of the sulphide ore, while the thiosulphate consumption was substantially reduced. The sulphide minerals partially decomposed in the pre-treatment process, exposing gold to the leach solution. Oxygen input by air bubbling and a longer contact time enhanced the oxidative ammonia pre-treatment process and hence accelerated subsequent thiosulphate leaching of the sulphide ore. Gold extraction in 0.8 M ammonia and 0.1 M thiosulphate solution after 24 h increased from 69% without pre-treatment to 81%, 84%, 90% and 94% respectively after 1, 3, 7 and 22 h pre-treatment. The consumption of sodium thiosulphate was 2.37 kg/t after 24 h leaching without pre-treatment, but was negligible after over 1 h oxidative ammonia pre-treatment. A counter-current leaching process was conducted in the leaching of the sulphide ore. The fresh leachant still gave higher leaching rates in contact with the pre-leached ore, while the pre-used leachant had significantly lower leaching kinetics and overall gold extraction in contact with the fresh ore. This 2-step counter-current leaching process proved that the leachant, other than the passivation, was the determinant factor causing the gold leaching rates to decrease after a certain time of leaching. The findings enable the thiosulphate leaching of high sulphide containing gold ores to be more efficient at lower thiosulphate consumption following the oxidative ammoniacal pre-treatment.

The Effect of Oxygen on Anaerobic Color Removal of Azo Dye in a Sequencing Batch Reactor

AbstractIn this study, various amounts of oxygen were added to the anaerobic phase of an anaerobic‐aerobic sequencing batch reactor (SBR) receiving azo dye remazol brilliant violet 5R to mimic the input of oxygen into the anaerobic zones of biological textile wastewater treatment plants. The effect of oxygen on the anaerobic biodegradative capability of the mixed microbial culture for remazol brilliant violet 5R was investigated. To investigate the effect of oxygen on anaerobic azo dye biodegradation, the anaerobic phase of the SBR cultures were exposed to a very low limited amount of oxygen for various air flow rates. Initially, an air flow rate of 20 mL/min was applied, further on the air flow rate in the anaerobic phase was increased up to 40 mL/min. System performance was determined by monitoring chemical oxygen demand, color removal rate, activities of anaerobic (azo reductase) and aerobic enzymes (catechol 2,3‐dioxygenase, catechol 1,2‐dioxygenase). The results of percentage COD reduction at each stage were similar for all runs, giving an overall reduction of 96%. Anaerobic color removal efficiency and azo reductase activity of anaerobic microorganisms were adversely affected by the addition of oxygen. Color removal efficiencies of the anaerobic phases decreased from 80% down to 42 and 38% for the limited oxygen conditions of 20 mL/min and 40 mL/min, respectively. It was observed that the activity of catechol 2,3‐dioxygenase and catechol 1,2‐dioxygenase, involved in breakage of aromatic rings, increased after they are exposed to oxygen limited conditions compared to fully anaerobic conditions. It was also observed that catechol 1,2‐dioxygenase enzyme activity increased by increasing the oxygen level on oxygen limited conditions in the anaerobic zone.

PHYTOREMEDIATION OF BTEX HYDROCARBONS: POTENTIAL IMPACTS OF DIURNAL GROUNDWATER FLUCTUATION ON MICROBIAL DEGRADATION

Volatile hydrocarbons have multiple potential fates in phytoremediation. This research investigated the relationship between biodegradation and plant uptake of BTEX compounds in laboratory and field settings. At a phytoremediation site, preliminary studies revealed minimal uptake into trees and enhanced degradation potential in the rhizosphere and in the bulk soil. Increased oxygen transport to the vadose zone caused by diurnal rise and fall of the water table was hypothesized to enhance degradation in the bulk soil. A detailed greenhouse study was then conducted to investigate potential bioremediation impacts using field-site soil and DN34 hybrid poplar trees. In rhizosphere soils, the contaminated-planted reactor had significantly higher BTEX degrader populations versus the uncontaminated-planted reactor, as was anticipated. The bulk soil in the planted-contaminated reactor had increased degrader populations than the unplanted-contaminated soil or planted-uncontaminated soil, and planting increased degradation throughout the soil profile, not just in the limited volume of rhizosphere soils. Oxygen diffusive and advective transport into reactors was modeled and calculated. Oxygen input in planted reactors was at least 3 to 5 times higher than in unplanted reactors, and increasing oxygen input lead to increased degrader populations in a linear manner. These results combined with the knowledge that high-transpiration trees draw the contaminated groundwater to the capillary fringe and the rhizosphere indicate that phytoremediation can aid microbial degradation via multiple mechanisms: increasing degrader populations, increasing oxygen input via groundwater diurnal fluctuations, and transporting contaminants to the biologically-enriched soil profile.

Culturing aerobic and anaerobic bacteria and mammalian cells with a microfluidic differential oxygenator.

In this manuscript, we report on the culture of anaerobic and aerobic species within a disposable multilayer polydimethylsiloxane (PDMS) microfluidic device with an integrated differential oxygenator. A gas-filled microchannel network functioning as an oxygen−nitrogen mixer generates differential oxygen concentration. By controlling the relative flow rate of the oxygen and nitrogen input gases, the dissolved oxygen (DO) concentration in proximal microchannels filled with culture media are precisely regulated by molecular diffusion. Sensors consisting of an oxygen-sensitive dye embedded in the fluid channels permit dynamic fluorescence-based monitoring of the DO concentration using low-cost light-emitting diodes. To demonstrate the general utility of the platform for both aerobic and anaerobic culture, three bacteria with differential oxygen requirements (E. coli, A. viscosus, and F. nucleatum), as well as a model mammalian cell line (murine embryonic fibroblast cells (3T3)), were cultured. Growth characteristics of the selected species were analyzed as a function of eight discrete DO concentrations, ranging from 0 ppm (anaerobic) to 42 ppm (fully saturated).

Decomposition of Organic Compounds in Water by Direct High Voltage Discharge

AbstractDegradation of phenol in water using direct high voltage discharge was investigated. The effects of some factors, including the pressure of the oxygen input, oxygen flow rate, ground electrode diameter, and initial pH were studied on the removal rate of phenol. Higher oxygen pressure and alkaline circumstance improved the process of decomposition. Under the condition of ground electrode inner diameter of 29 mm, oxygen flow rate of 60 mL/min, the removal rate reached 90 % after 180‐min discharge treatment. The solution conductivity was found to change with the removal rate of phenol accordingly.

A recombinant E. coli bioprocess for hyaluronan synthesis

An Escherichia coli strain, JM109, was successfully engineered into an efficient hyaluronic acid (HA) producer by co-expressing the only known class-II HA synthase from a Gram-negative bacterium (Pasteurella multocida) and uridine diphosphate-glucose dehydrogenase from E. coli K5 strain. The engineered strain produced about 0.5 g/L HA in shake flask culture and about 2.0-3.8 g/L in a fed-batch fermentation process in a 1-L bioreactor. The sharp increase in viscosity associated with HA accumulation necessitated pure oxygen supplement to maintain fermentation in aerobic regime. Precursor supply during HA synthesis was probed by glucosamine supplement, which shortens biosynthesis pathway and eliminates one step requiring ATP. HA synthesis was increased with glucosamine supplement from 2.7 to 3.7 g/L (37%), which was mirrored with a concomitant 42% decrease in pure oxygen input, suggesting a close connection between energy metabolism and precursor supply. Decoupling HA synthesis from cell growth by using fosfomycin (an inhibitor for cell wall synthesis) led to a 70% increase in HA synthesis, suggesting detrimental effects on HA synthesis from cell growth via precursor competition. This study demonstrates a potentially viable process for HA based on a recombinant E. coli strain. In addition, the precursor supply limitation identified in this study suggests new engineering targets in subsequent metabolic engineering efforts.

The Development of Ni/Dolomite Catalyst in Simultaneous Biomass Gasification and Reforming in Fluidized Bed

Simultaneous gasification and steam reforming of t he biomass on Ni/dolomite catalyst in fluidized bed reactor were studied in the gaseous p roduction in the one stage reactor. Problem statement: The parameters such as temperature, steam flow rat e, biomass feed rate, gas flow rate for fluidization, oxygen flow rate and catalyst types w ere studied to produce the high gaseous products including tar elimination. Approach: The temperature at 780°C, steam flow rate of 222 mmoL h -1 , gas flow rate for fluidization 450 mL min -1 and oxygen input 50 mL min -1 were found to be the suitable conditions. The Ni/Dolomite and the developed Ni/Dolomite were studied about their performance. Results: It was confirmed that Ni/Dolomite and newly developed Ni-WO 3/Dolomite show high performance in biomass gasification. Conclusion/Recommendations: It was claimed that Ni/Dolomite catalyst was the effective and give bes t performance for tar cracking. Newly developed Ni-WO 3/Dolomite catalyst was investigated to resist sulfu r nd coking. Three types of catalyst were used in the biomass gasification, which are Ni/Dolo mite, Ni/Dolomite+Silica binder and Ni- WO 3/Dolomite. From the XRD analysis, structures of typ e 1 (Ni/dolomite) and type 2 (Ni/Dolomite+Silica binder) were similar which were in CaCO 3, MgNiO 2, NiO and MgO forms. Type 3 (Ni-WO 3/Dolomite) was CaWO 4, MgNiO 2, NiO and MgO forms. When the catalytic gasification was operated, newly Ni- WO 3/Dolomite catalyst was the best catalyst for bamboo and palm shell biomasses, which could produce the high carbon monoxide and hydrogen but low methane and carbon dioxide were found. Carbon deposition on catalyst was around 0.37 mg according to the TG analysis.

Promotion of Coconut Shell Gasification by Steam Reforming on Nickel-Dolomite

Biomass gasification by the use of metallic nickel as active metal on dolomite support has been chosen as catalyst because of its activity in biomass steam gasification and tar reduction. The purpose of this study is to study the effects of critical parameters on product gas compositions such as temperature, steam to carbon ratio (S/C) and oxygen input. The results showed the increasing carbon conversion to gas from 44.13-78.43% whereas tar was decreased from 19.55-1.4% at temperature of 800°C and S/C 0.95. It is found that Nickel-dolomite is effective for tar reduction and for improving the quality of syngas derived from biomass which is a renewable energy source.

Compartment model for steam reforming of methane in a membrane-assisted bubbling fluidized-bed reactor

Abstract A compartment model was developed to describe the flow pattern of gas within the dense zone of a membrane-assisted fluidized-bed reactor (MAFBR), in the bubbling mode of operation for steam reforming of methane both with (adiabatic) and without (isothermal) entering oxygen. Considering such a flow pattern and using the experimental data reported elsewhere [Roy S, Pruden BB, Adris AM, Grace JR, Lim CJ. Fluidized-bed steam methane reforming with oxygen input. Chem Eng Sci 1999; 54:2095–2102.], the parameters of the developed model (i.e., number of compartments for the bubble and emulsion phases) were determined and fair agreements were obtained between model predictions and experimental data. The developed model was utilized to describe the behavior of an industrial scale adiabatic and isothermal MAFBR. Moreover, the influences of various operating and design parameters such as steam-to-methane ratio (SMR), oxygen-to-methane ratio (OMR), operating temperature and pressure, and the number of hydrogen membrane tubes on the performance capability of the MAFBR were investigated. Furthermore, the performance capability of the MAFBR was optimized subject to the various operating and design constraints, including 1 ≤ SMR ≤ 4 and 500 ≤ T ≤ 1250 K, in the bubbling regime.

Sources of oxygen flux in groundwater during induced bank filtration at a site in Berlin, Germany

The microbial degradation of pharmaceuticals found in surface water used for artificial recharge is strongly dependent on redox conditions of the subsurface. Furthermore the durability of production wells may decrease considerably with the presence of oxygen and ferrous iron due to the precipitation of trivalent iron oxides and subsequent clogging. Field measurements are presented for oxygen at a bank filtration site in Berlin, Germany, along with simplified calculations of different oxygen pathways into the groundwater. For a two-dimensional vertical cross-section, oxygen input has been calculated for six scenarios related to different water management strategies. Calculations were carried out in order to assess the amount of oxygen input due to (1) the infiltration of oxic lake water, (2) air entrapment as a result of water table oscillations, (3) diffusive oxygen flux from soil air and (4) infiltrating rainwater. The results show that air entrapment and infiltrating lake water during winter constitute by far the most important mechanism of oxygen input. Oxygen input by percolating rainwater and by diffusive delivery of oxygen in the gas phase is negligible. The results exemplify the importance of well management as a determining factor for water oscillations and redox conditions during artificial recharge.

The use of the Laerdal infant resuscitator results in the delivery of high oxygen fractions in the absence of a blender

High oxygen increases morbidity and mortality. Current guidelines in Neonatal Resuscitation Programme (NRP) state if self-inflating bags are used with an input FiO2 of 1.0 without an oxygen reservoir a delivered safe FiO2 of approximately 0.40 is achieved. This conflicts with manufacturer findings (Laerdal infant resuscitator (LIR)). We assessed FiO2 delivery by the LIR, varying oxygen reservoir (OR) use, ventilation and input flowrates. A test lung was connected to the LIR and oxygen analyzer. FiO2 delivery was measured under these four conditions: LIR plus OR and FiO2 1.0 or FiO2 0.40; LIR minus OR and FiO2 of 1.0 and 0.40. Variations of ventilation patterns in random order, assessed tidal volumes (from 20 and 40mL), ventilation rates (from 30, 40 and 60breaths/min), and input flowrates (from 1, 3, 5, 8, and 10Lpm). A wash-out period of 1min of ventilation was followed by measure of FiO2 during manual ventilation. The measured FiO2 with the LIR delivered the same source FiO2 under all experimental conditions for flowrates of 5Lpm and greater; irrespective of the OR presence or absence. At flowrates of 1 and 3Lpm, FiO2 was lower, with and without the reservoir, but the reservoir was visibly identified as not filled. Our findings support the manufacturers performance specification that high input FiO2 results in high delivered FiO2 with/without an OR. These results dispute the 2006 NRP guidelines that state "in the absence of a reservoir (oxygen) the delivered oxygen is reduced to about 40%".

Abatement of Trichloromethane by Using Nonthermal Plasma Reactors

This work investigated the destruction of a halogenated carbon (trichloromethane) using different types of nonthermal plasma reactors. Three reactors, i.e., a surface discharge reactor, a dielectric-packed bed reactor and a barrier discharge reactor with a perforated dielectric tube, were compared with respected to the trichloromethane destruction efficiency. The effect of oxygen content and input power on the trichloromethane destruction was examined, and the byproducts were analyzed to elucidate the destruction pathways. The dielectric-packed bed reactor was found to show better performance in the trichloromethane destruction than the other two reactors. The increase in the oxygen content decreased the destruction efficiency, and the highest destruction efficiency was obtained at oxygen content 0.5%. The calculations for electron-molecule collisions indicated that the most abundant reactive species initiating the destruction of trichloromethane are metastable nitrogen molecules. The major byproducts were CO and Cl2, and the formations of NO2 and N2O were also significant.