scholarly journals Gas-Dynamic Kinetics of Vapour Sampling in the Detection of Explosives

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4409
Author(s):  
Vladimir M. Gruznov ◽  
Alexander B. Vorozhtsov
Keyword(s):  
High Speed ◽  
Wire Mesh ◽  
Diffusion Flow ◽  
High Concentration ◽  
Metal Mesh ◽  
Sorption Concentration ◽  
Dynamic Sorption ◽  
Specific Frequency ◽  
Detection Of Explosives ◽  
Kinetics Of

The dynamic sorption concentration of explosive vapours on concentrators made of a metal mesh, and the transportation of explosive vapours through the extended metal channels are considered. The efficiency of the concentration and transportation is determined by the breakthrough of the substance’s molecules through the channels. The research methods we used were breakthrough calculation theory and experiment. When calculating the breakthrough, a mesh was presented as a set of parallel identical channels. Wire mesh and extended channels were made of stainless steel. The breakthrough is determined through the specific frequency of the collisions between the molecules and the channel’s surface. This is presented as a function of the ratio of the substance diffusion flow to the channel’s surface to the airflow through the channel. The conditions for high-speed concentration, complete capture of explosive vapours, and low vapour losses during their transportation through the extended channels were determined theoretically and experimentally. For a concentrator made of a mesh, the condition of a high concentration rate at a high breakthrough (up to 80%) was determined. The described sorption concentration is used in portable gas chromatographic detectors of explosive vapours of the EKHO series.

Metal Mesh Foil Bearing: Effect of Motion Amplitude, Rotor Speed, Static Load, and Excitation Frequency on Force Coefficients

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Luis San Andrés ◽  
Thomas Abraham Chirathadam
Keyword(s):  
Energy Dissipation ◽  
High Speed ◽  
Mechanical Energy ◽  
Excitation Frequency ◽  
Wire Mesh ◽  
Test Element ◽  
Metal Mesh ◽  
Force Coefficients ◽  
Damping Coefficients ◽  
Mechanical Energy Dissipation

Metal mesh foil bearings (MMFBs), simple to construct and inexpensive, are a promising bearing technology for oil-free microturbomachinery operating at high speed and high temperature. Prior research demonstrated the near friction-free operation of a MMFB operating to 60 krpm and showing substantial mechanical energy dissipation characteristics. This paper details further experimental work and reports MMFB rotordynamic force coefficients. The test rig comprises a turbocharger driven shaft and overhung journal onto which a MMFB is installed. A soft elastic support structure akin to a squirrel cage holds the bearing, aiding to its accurate positioning relative to the journal. Two orthogonally positioned shakers excite the test element via stingers. The test bearing comprises a cartridge holding a Copper wire mesh ring, 2.7 mm thick, and a top arcuate foil. The bearing length and inner diameter are 38 mm and 36.5 mm, respectively. Experiments were conducted with no rotation and with journal spinning at 40–50 krpm, with static loads of 22 N and 36 N acting on the bearing. Dynamic load tests spanning frequencies from 150 to 450 Hz were conducted while keeping the amplitude of bearing displacements at 20 µm, 25 µm, and 30 µm. With no journal spinning, the force coefficients represent the bearing elastic structure alone because the journal and bearing are in contact. The direct stiffnesses gradually increase with frequency while the direct damping coefficients drop quickly at low frequencies (< 200 Hz) and level off above this frequency. The damping combines both viscous and material types from the gas film and mesh structure. Journal rotation induces airborne operation with a hydrodynamic gas film separating the rotor from its bearing. Hence, cross-coupled stiffness coefficients appear although with magnitudes lower than those of the direct stiffnesses. The direct stiffnesses, 0.4 to 0.6 MN/m within 200–400 Hz, are slightly lower in magnitude as those obtained without journal rotation, suggesting the air film stiffness is quite high. Bearing direct stiffnesses are inversely proportional to the bearing motion amplitudes, whereas the direct equivalent viscous damping coefficients do not show any noticeable variation. All measurements evidence a test bearing system with material loss factor (γ) ∼ 1.0, indicating significant mechanical energy dissipation ability.

Metal Mesh Foil Bearing: Effect of Motion Amplitude, Rotor Speed, Static Load, and Excitation Frequency on Force Coefficients

2011 ◽  
Author(s):  
Luis San Andre´s ◽  
Thomas Abraham Chirathadam
Keyword(s):  
Energy Dissipation ◽  
High Speed ◽  
Mechanical Energy ◽  
Excitation Frequency ◽  
Wire Mesh ◽  
Test Element ◽  
Metal Mesh ◽  
Force Coefficients ◽  
Damping Coefficients ◽  
Mechanical Energy Dissipation

Metal mesh foil bearings (MMFBs), simple to construct and inexpensive, are a promising bearing technology for oil-free microturbomachinery operating at high speed and high temperature. Prior research demonstrated the near friction-free operation of a MMFB operating to 60 krpm and showing substantial mechanical energy dissipation characteristics. This paper details further experimental work and reports MMFB rotordynamic force coefficients. The test rig comprises of a turbocharger driven shaft and overhung journal onto which a MMFB is installed. A soft elastic support structure akin to a squirrel cage holds the bearing, aiding to its accurate positioning relative to the journal. Two orthogonally positioned shakers excite the test element via stingers. The test bearing comprises of a cartridge holding a Copper wire mesh ring, 2.7 mm thick, and a top arcuate foil. The bearing length and inner diameter are 38 mm and 36.5 mm, respectively. Experiments were conducted with no rotation and with journal spinning at 40–50 krpm, with static loads of 22 N and 36 N acting on the bearing. Dynamic load tests spanning frequencies from 150 to 450 Hz were conducted while keeping the amplitude of bearing displacements at 20 μm, 25 μm, and 30 μm. With no journal spinning, the force coefficients represent the bearing elastic structure alone since the journal and bearing are in contact. The direct stiffnesses gradually increase with frequency while the direct damping coefficients drop quickly at low frequencies (< 200 Hz) and level off above this frequency. The damping combines both viscous and material types from the gas film and mesh structure. Journal rotation induces airborne operation with a hydrodynamic gas film separating the rotor from its bearing. Hence, cross-coupled stiffness coefficients appear though with magnitudes lower than those of the direct stiffnesses. The direct stiffnesses, 0.4 to 0.6 MN/m within 200–400 Hz, are slightly lower in magnitude as those obtained without journal rotation suggesting the air film stiffness is quite high. Bearing direct stiffnesses are inversely proportional to the bearing motion amplitudes, whereas the direct equivalent viscous damping coefficients do not show any noticeable variation. All measurements evidence a test bearing system with material loss factor (γ) ∼ 1.0, indicating significant mechanical energy dissipation ability.

Vancomycin Adsorption During in vitro Model of Hemoperfusion with HA380 Cartridge

Nephron ◽  
2021 ◽  
pp. 1-7
Author(s):  
Ilaria Godi ◽  
Anna Lorenzin ◽  
Silvia De Rosa ◽  
Gianlorenzo Golino ◽  
Maira Knust ◽  
...  
Keyword(s):  
Complete Removal ◽  
Potential Interaction ◽  
Blood Purification ◽  
Therapeutic Monitoring ◽  
High Concentration ◽  
Langmuir Isotherm Model ◽  
Vitro Model ◽  
Kinetics Of ◽  
Balanced Solution

<b><i>Introduction:</i></b> A critical point for using blood purification during sepsis may be the potential interaction with antimicrobial therapy, the mainstay of sepsis treatment. The aim of our study was to investigate the vancomycin removal during hemoperfusion (HP) using HA380 cartridge. <b><i>Methods:</i></b> This is an experimental study, in which 500 mL of solution was circulated in a closed-circuit (blood flow of 250 mL/min) simulating HP ran using HA380. Vancomycin was added to reach a through concentration or a very high concentration to evaluate the removal ratio (RR) during 120 min of HP. Comparison between blood-crystalloid solution and balanced solution was performed by using Kruskal-Wallis test. The kinetics of vancomycin removal and the adsorption isotherm were evaluated. <b><i>Results:</i></b> We found a complete removal of vancomycin at baseline through concentration of 23.0 ± 7.4 mg/L. Using extremely high concentration (baseline 777.0 ± 62.2 mg/L), RR was 90.1 ± 0.6% at 5 min and 99.2 ± 0.6% at 120 min. No difference in terms of RR was found between blood-crystalloid mixture and balanced solution. The kinetics of the vancomycin reduction followed an exponential decay. Repeated boluses (total amount of 2,000 mg) resulted in cumulative adsorption of 1,919.4 mg with RR of 96.6 ± 1.4%, regardless of the amount injected (100 vs. 500 mg). Vancomycin adsorption onto HA380 followed the Langmuir isotherm model. <b><i>Conclusions:</i></b> A considerable amount of vancomycin was rapidly removed during in vitro HP with HA380. Clinical studies are needed to determine whether this may lead to underdosing. Drug therapeutic monitoring is highly recommended when using HA380 for blood purification in patients receiving vancomycin.

scholarly journals Leaching Titaniferous Magnetite Concentrate by Alkaline Aqueous Solution

2021 ◽  
Author(s):  
Ke Guo ◽  
Shaoyan Wang ◽  
Renfeng Song ◽  
Zhiqiang Zhang
Keyword(s):  
Aqueous Solution ◽  
Alkali Concentration ◽  
Water Usage ◽  
X Ray Diffraction ◽  
High Concentration ◽  
X Ray ◽  
Iron Concentrate ◽  
Titaniferous Magnetite ◽  
Magnetite Concentrate ◽  
Kinetics Of

AbstractLeaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

Study on the Formaldehyde Adsorption Kinetics of Dry Waters

2014 ◽  
Vol 809-810 ◽  
pp. 907-911
Author(s):  
Jun Long Wang ◽  
Jie Hou ◽  
Ting Jiang ◽  
Yong Jun He ◽  
Yao Dong Liang
Keyword(s):  
Adsorption Kinetics ◽  
High Speed ◽  
Adsorption Process ◽  
Average Diameter ◽  
Adsorption Rate ◽  
Absorption Kinetics ◽  
Order Model ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Formaldehyde Adsorption

Dry waters with an average diameter of 82 μm were prepared by a high speed mixed route. The formaldehyde absorption kinetics of dry waters was investigated by simulating indoor formaldehyde pollution in glass chamber. The results showed that pseudo-second order model could be used to simulate the adsorption process; the adsorption rate was highest in the initial 60 minutes; when the adsorption lasted for 180 minutes, the adsorption reached equilibrium.

High-speed fluorescence detection of explosives vapor

1999 ◽  
Author(s):  
Keith J. Albert ◽  
Michael L. Myrick ◽  
Steve B. Brown ◽  
Fred P. Milanovich ◽  
David R. Walt
Keyword(s):  
Fluorescence Detection ◽  
High Speed ◽  
Detection Of Explosives

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

scholarly journals Κινητική της αμμωνίας εις το περιτοναϊκόν υγρόν

1968 ◽  
Author(s):  
Αναστάσιος Εμμανουήλ
Keyword(s):  
Ascitic Fluid ◽  
Peritoneal Fluid ◽  
Ammonium Citrate ◽  
Blood Ammonia ◽  
High Concentration ◽  
Group 2 ◽  
Fixed Times ◽  
Kinetics Of ◽  
Cirrhotic Group ◽  
Group 1

The kinetics of ammonia between blood and peritoneal fluid on 18 patiens was studied. Ten grams of ammonium citrate were given by mouth; the concentrations of ammonia in the blood and in the peritoneal fluid were comprared after determining the values at fixed times. The cases were divided in two groups: group 1, included eight patients with cirrhosis of the liver, group 2, included patients with ascites of other than liver cirrhosis aetiology, five of whom had carcinoma of the liver and'or of the peritoneal, two patients with lymphosarcoma, one with kidneysarcoma (Bour neville Syndrome) and two cases with congestive heart failure. The following conclusions have drawn : 1. The ammonia concentrations in the ascitic fluid of the cirrhotic group (group 1) before ammonium citrate loading was found to be higher than in the blood. 2. The highest concentration of the ammonia in the ascitic fluid was found two hours after loading and fell to the pre-loading level three hours later. 3. The curve formed by the ammonia values and ascitic fluid is similar to that of the blood. 4. The values of blood —and ascitic fluid—ammonia and the respective ourves in cases of cardiac failure resembled those found in cirrhotics. 5. In cases of neoplasms the fluctuations of ammonia concentrations in the blood and in the peritoneal fluid are minimal and the curves are flat. 6. In lymphosarcoma and kidneysarcoma the pre-loading values of blood ammonia are higher than in the peritoneal fluid.7. High concentration of blood and peritoneal fluid ammonia without appreciable fluctuations might suggest liver cancer on cirrhotic substrate.

scholarly journals Influence of microadditive of carbon dioxide on the kinetics of boiling-up of superheated w-pentane

2021 ◽  
Vol 2039 (1) ◽  
pp. 012027
Author(s):  
S A Perminov ◽  
E V Lipnyagov ◽  
M A Parshakova
Keyword(s):  
High Speed ◽  
Gas Adsorption ◽  
Glass Tube ◽  
Initial Value ◽  
Active Centers ◽  
High Speed Video ◽  
Inner Surface ◽  
Vertical Glass ◽  
Attainable Superheat ◽  
Kinetics Of

Abstract The effect of a low-boiling impurity (CO2 gas <1.5% mol) on the kinetics of boiling-up of superheated n-pentane in a vertical glass tube have been studied by high-speed video (2050 fps). The method of continuous pressure decrease from 2.00 to 0.10 MPa (in the temperature range of 100.2-145.1 °C), as well as the method of measuring the lifetimes of superheated liquids at 0.10 MPa (90.2-134.1 °C) have been used. The inner surface of the tube has two visible defects, one of which defines the boundary of the attainable superheat. After degassing the system, the defects of tube cease to play an appreciable role, the active centers are redistributed. The temperature of the attainable superheat increases from the initial value by 20 °C in tests with gas and by 10 °C in subsequent tests without it. The result obtained may be related to physical gas adsorption on the glass surface during the process of evacuation of the system.

Modelling of microbial processes that govern degradation of organic substrates in soil, with special reference to pesticides

1990 ◽  
Vol 329 (1255) ◽  
pp. 369-373 ◽  
Keyword(s):  
Microbial Population ◽  
Large Fraction ◽  
Organic Substrates ◽  
High Concentration ◽  
Deterministic Models ◽  
Soil Microbial ◽  
Low Concentrations ◽  
Biokinetic Parameters ◽  
Soil Microbial Population ◽  
Kinetics Of

We tried to develop deterministic models for kinetics of 2,4-D breakdown in the soil based on the following considerations: (i) at low concentrations degradation results from maintenance consumption by a large fraction of the soil microbial population; (ii) at high concentration in addition to the maintenance consumption there is a growth-associated carbon incorporation by a small specific microbial population. Values for the biokinetic parameters are consistent with those commonly found in the literature. Comparison between observed and simulated curves suggests that a non-negligible part of the pesticidal carbon exists as microbial by-products.

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