Inhibition of Microbial Growth by Low-Pressure and Ambient Pressure Gases

2001 ◽  
pp. 245-280
Author(s):  
Christopher R. Loss ◽  
Joseph H. Hotchkiss
Keyword(s):  
Microbial Growth ◽  
Ambient Pressure ◽  
Low Pressure

scholarly journals (47) Optimal Low Pressure Conditions for Long-term Storage of Fresh Commodities Kill Caribbean Fruit Fly Eggs and Larvae

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1087B-1087
Author(s):  
Thomas L. Davenport ◽  
Stanley P. Burg ◽  
Thomas L. White
Keyword(s):  
Fruits And Vegetables ◽  
Insect Pests ◽  
Ambient Pressure ◽  
Fruit Fly ◽  
Radiant Heat ◽  
Low Pressure ◽  
Hot Water ◽  
Tropical Fruit ◽  
Caribbean Fruit Fly ◽  
Eggs And Larvae

U.S. regulations prevent importation of fresh horticultural commodities that have not received an approved quarantine treatment assuring 100% mortality of potentially invasive insect pests. Because imported mangoes are likely to be infested by the Caribbean fruit fly (Anastrepha suspensa Loew) and other tropical fruit flies such as A. ludens Loew, A. striata, A. distincta, A. fraterculus, A. serpentina, or A. oblique, they must be hot-water treated prior to shipment in order to satisfy quarantine requirement. Hot water treatment often damages the fruit, especially if it is not fully mature. Hypobaric (low pressure = LP) intermodal shipping containers developed by the VacuFreshSM Corp. preserve fresh commodities, such as horticulturally mature mangoes, far longer than is possible using other technologies. We tested the ability of over 70,000 Caribbean fruit fly eggs and larvae to survive a simulated optimal hypobaric condition for shipment of mangoes (15 mm Hg, 98% RH, at the lowest, safe non-chilling temperature, 13 °C). A. suspensa eggs or larvae were maintained on agar media, flushed with one air change per hour at the storage pressure, and shielded with Mylar to prevent radiant heat uptake and limit evaporative cooling. Nearly 98% of the eggs and larvae were killed within 1 week at 15 mm Hg in eight replicated experiments. All eggs were killed at that pressure by 11 days, whereas a significant number survived at ambient pressure. Shipment of fresh produce using this technology promises to provide quarantine control while preserving the freshness of fully mature tropical fruits and vegetables.

scholarly journals Chemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage

2015 ◽  
Vol 6 (7) ◽  
pp. 3965-3974 ◽  
Author(s):  
R. Michalsky ◽  
A. M. Avram ◽  
B. A. Peterson ◽  
P. H. Pfromm ◽  
A. A. Peterson
Keyword(s):  
Energy Storage ◽  
Ammonia Synthesis ◽  
Ambient Pressure ◽  
Design Principles ◽  
Low Pressure ◽  
Chemical Looping ◽  
Metal Nitride

Design principles for reducible metal nitride catalysts are developed and demonstrated for ambient-pressure solar-driven N2 reduction into NH3.

High Temperature Oxidation Behavior of MoSi2 under Low Pressure Atmosphere

2007 ◽  
Vol 561-565 ◽  
pp. 427-430 ◽  
Author(s):  
Akira Ibano ◽  
Kyosuke Yoshimi ◽  
Akira Yamauchi ◽  
Rong Tu ◽  
Kouichi Maruyama ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Ambient Pressure ◽  
Low Pressure ◽  
Initial Oxidation ◽  
Temperature Oxidation ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
High Temperature Oxidation Behavior

In this study, the high temperature oxidation behavior of polycrystalline MoSi2 in a low-pressure atmosphere was investigated. Polycrystalline MoSi2 was produced by the spark plasma sintering process. Oxidation tests were carried out at 1500°C at either 10Torr or 760Torr in an Ar-20%O2 atmosphere. For both conditions, the weight change peaked at the initial oxidation stage, and then their weights gradually increased with increasing oxidation time. The sample weight became heavier in the ambient pressure than in the low-pressure, but the evaporation oxidation was not significant in the low-pressure condition. After the low-pressure oxidation tests, the formation of Mo5Si3 in the MoSi2 substrate was identified. The oxidation resistance of MoSi2 at 1500°C is discussed based on the obtained results.

Investigation of the Effect of Plume Number on Spray Collapse

2019 ◽  
Author(s):  
Panos Sphicas
Keyword(s):  
Ambient Temperature ◽  
High Velocity ◽  
Recirculation Zone ◽  
Ambient Pressure ◽  
Low Pressure ◽  
Ambient Conditions ◽  
Single Entity ◽  
Injection Duration ◽  
Pressure Region ◽  
Entrained Air

Abstract The plumes of a gasoline spray collapse into a single entity under the influence of ambient pressure, ambient temperature and injection duration. Previous work by the author studied experimentally [1] and numerically [2] the phenomenon of spray collapse. It was observed that the entrained air from every single plume, accumulatively creates a recirculation zone in the middle of the spray. The recirculation zone of high velocity, creates a low pressure region, which causes the collapse of the spray. In this paper, the influence of the number of plumes in the spray, is investigated numerically. The plume angle and ambient conditions matched Spray G, but the number of plumes was varied from two to eight. The effect of the plume number on the spray collapse was investigated numerically. It was evident that increased number of plumes in the spray promotes spray collapse.

scholarly journals Effect of Oxygen Mole Fraction on Static Properties of Pressure-Sensitive Paint

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1062
Author(s):  
Tomohiro Okudera ◽  
Takayuki Nagata ◽  
Miku Kasai ◽  
Yuji Saito ◽  
Taku Nonomura ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Mole Fraction ◽  
Ambient Pressure ◽  
Low Pressure ◽  
Pressure Sensitive Paint ◽  
Partial Pressure Of Oxygen ◽  
Static Properties ◽  
Pressure Sensitive ◽  
High Partial Pressure ◽  
Oxygen Mole Fraction

The effects of the oxygen mole fraction on the static properties of pressure-sensitive paint (PSP) were investigated. Sample coupon tests using a calibration chamber were conducted for poly(hexafluoroisopropyl methacrylate)-based PSP (PHFIPM-PSP), polymer/ceramic PSP (PC-PSP), and anodized aluminum PSP (AA-PSP). The oxygen mole fraction was set to 0.1–100%, and the ambient pressure (Pref) was set to 0.5–140 kPa. Localized Stern–Volmer coefficient Blocal increased and then decreased with increasing oxygen mole fraction. Although Blocal depends on both ambient pressure and the oxygen mole fraction, its effect can be characterized as a function of the partial pressure of oxygen. For AA-PSP and PHFIPM-PSP, which are low-pressure- and relatively low-pressure-type PSPs, respectively, Blocal peaks at PO2ref<12 kPa. In contrast, for PC-PSP, which is an atmospheric-pressure-type PSP in the investigated range, Blocal does not have a peak. Blocal has a peak at a relatively high partial pressure of oxygen due to the oxygen permeability of the polymer used in the binder. The peak of SPR, which is the emission intensity change with respect to normalized pressure fluctuation, appears at a lower partial pressure of oxygen than that of Blocal. This is because the intensity of PSP becomes quite low at a high partial pressure of oxygen even if Blocal is high. Hence, the optimal oxygen mole fraction depends on the type of PSP and the ambient pressure range of the experiment. This optimal value can be found on the basis of the partial pressure of oxygen.

scholarly journals The height limit of a siphon

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
A. Boatwright ◽  
S. Hughes ◽  
J. Barry
Keyword(s):  
Sea Level ◽  
Vapour Pressure ◽  
Ambient Pressure ◽  
Barometric Pressure ◽  
Low Pressure ◽  
Conclusive Evidence ◽  
Differential Pressure ◽  
Maximum Height ◽  
Reservoir Level ◽  
Pressure Region

Abstract The maximum height of a siphon is generally assumed to be dependent on barometric pressure—about 10 m at sea level. This limit arises because the pressure in a siphon above the upper reservoir level is below the ambient pressure and when the height of a siphon approaches 10 m, the pressure at the crown of the siphon falls below the vapour pressure of water causing water to boil breaking the column. After breaking, the columns on either side are supported by differential pressure between ambient and the low-pressure region at the top of the siphon. Here we report an experiment of a siphon operating at sea level at a height of 15 m, well above 10 m. Prior degassing of the water prevented cavitation. This experiment provides conclusive evidence that siphons operate through gravity and molecular cohesion.

scholarly journals Hypobaria Affects Gas Exchange, Ethylene Evolution and Growth of Lettuce in NASA Advanced Life Support Systems (ALS)

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 794A-794
Author(s):  
Chuanjiu He ◽  
Fred Davies* ◽  
Ronald Lacey ◽  
Que Ngo
Keyword(s):  
Gas Exchange ◽  
Plant Growth ◽  
Life Support ◽  
Dark Respiration ◽  
Ambient Pressure ◽  
Low Pressure ◽  
High Light ◽  
Assimilation Rate ◽  
Ethylene Evolution ◽  
Process Gas

Elevated levels of ethylene occur in enclosed crop production systems and in space-flight environments—leading to adverse plant growth and sterility. There are engineering advantages in growing plants at hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or spaceflight environments. Objectives of this research were to characterize the influence of hypobaria on gas exchange and ethylene evolution of lettuce (Lactuca sativa L. cv. Buttercrunch). Lettuce was grown under variable total gas pressures [50 and 101 kPa (ambient)]. The six chambered, modular low plant growth (LPPG) system has a Rosemount industrial process gas chromatograph (GC) for determining gas concentrations of oxygen (O2), carbon dioxide (CO2) and nitrogen (N). With the LPPG system, changes in CO2 can be tracked during the light and dark periods on a whole canopy basis, and transpirate collected as a measurement of transpiration. During short growth periods of up to seven days, growth was comparable between low and ambient pressure. However, there was a tendency for leaf tip burn under ambient pressure, in part because of higher ethylene levels. Tip burn increased under high light (600 vs. 300 μmol·m-1·s-1) and high CO2 (600 vs. 100 Pa). The CO2 assimilation rate and dark respiration tended to be higher under ambient conditions. High humidity (100%) reduced CO2 assimilation rate compared to 70% RH. Ethylene was increased by high light (600 vs. 300 μmol·m-1·s-1) and high CO2 (600 vs. 100 Pa). Ethylene was higher under ambient than low pressure. Enhanced plant growth under low pressure may be attributed to reduced ethylene production and decreased dark respiration (lower night consumption of metabolites).

scholarly journals (305) Influence of Hypobaria on Gas Exchange and Growth of Lettuce for Advanced Life Support Systems (ALS)

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1011B-1011
Author(s):  
Chuanjiu He ◽  
Fred T. Davies ◽  
Ronald Lacey
Keyword(s):  
Biomass Production ◽  
Space Flight ◽  
Crop Production ◽  
Life Support ◽  
Production Systems ◽  
Dark Respiration ◽  
Ambient Pressure ◽  
Advanced Life Support ◽  
Low Pressure ◽  
Production Cycles

There are advantages in growing plants under hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or space-flight environments. Elevated levels of the plant hormone ethylene occur in enclosed crop production systems and in space-flight environments—leading to adverse plant growth and sterility. Objectives of this research were to characterize the influence of hypobaria on growth and ethylene evolution of lettuce (Lactuca sativa L. cv. Buttercrunch). Growth was comparable in lettuce grown under low (25 kPa) and ambient (101 kPa) total gas pressures. However, tip burn occurred under ambient, but not low pressure—in part because of adverse ethylene levels. Under ambient pressure, there were higher CO2 assimilation rates and dark respiration rates (higher night consumption of metabolites) compared to low pressure. This could lead to greater growth (biomass production) of low pressure plants during longer crop production cycles.

scholarly journals Study on Combustion Properties of Aviation Carpet under Low Ambient Pressure

2020 ◽  
Vol 38 (2) ◽  
pp. 319-324
Author(s):  
Xuhong Jia ◽  
Xiaoguang Yang ◽  
Song Huang ◽  
Maoyong Zhi ◽  
Xinhua Zhu
Keyword(s):  
Carbon Monoxide ◽  
Volume Fraction ◽  
Ambient Pressure ◽  
Ignition Time ◽  
Normal Pressure ◽  
Low Pressure ◽  
Combustion Properties ◽  
Civil Aircraft ◽  
Transport Condition ◽  
Normal Transport

The flame-retardant materials in the cabin of civil aircraft is possible to induce fire accident, which can cause certain threat to the operation safety of aircraft. The cabin pressure of civil aircraft is generally maintained at 75~84 kPa under normal transport condition, and the combustion behavior of aviation carpet will change under this pressure. Combustion properties of an aviation carpet, selected from civil aircraft, were studied at Guanghan City (520 m altitude) and Kangding airport (4290 m altitude), Sichuan province of China in this work, respectively. The results showed that the smoke density of the aviation carpets increased sharply and the decreasing rate of the oxygen volume fraction became more quickly under low pressure. Furthermore, the rising rate of carbon dioxide volume fraction also became rapidly with the decrease of the ambient pressure. The content of the carbon monoxide under low pressure was lower than that under normal pressure at the beginning of the combustion. However, the carbon monoxide production increased sharply when the combustion lasted for 4 minutes. In addition, the ignition time of the aviation carpet was shorter under low pressure.

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