DESIGN, FABRICATION, AND TEST OF A SILICATE MICROSENSOR

2009 ◽  
Vol 21 (06) ◽  
pp. 389-394
Author(s):  
Chih-Wei Wu ◽  
Ting-I Wu ◽  
Wei-Han Chen ◽  
Long-Sun Huang
Keyword(s):  
Detection Limit ◽  
Linear Function ◽  
Chemical Sensors ◽  
Gas Bubbles ◽  
Value Added ◽  
Signal Enhancement ◽  
Air Bubbles ◽  
Silicate Concentration ◽  
R Value ◽  
Experimental Detection Limit

This work describes a portable microsensor for analyzing the silicate concentration in water. Conventionally adopted silicate analysis methods involve bulky instrumentation that are limited in portability and immediateness. The proposed silicate microsensor consists of a microliquid core waveguide, passive spiral micromixer, and bubble traps that possess excellent signal enhancement properties. The microsensor size is 52 × 26 mm, while each measurement requires only 115 μl of a sample and reagents, thereby reducing the sample requirement for a considerable amount of time and work to collect expensive reagents. The spiral micromixer has a mixing capability superior to that of a premix mixture. Bubble traps have been developed to trap air bubbles formed in the microchannel in order to prevent gas bubbles from interfering with the measurements. As a linear function of silicate concentration, the absorbance response ranges from 0 to 250 nM. Additionally, the linearity is excellent with a linear R value of 0.9985 and the experimental detection limit is 8.9 nM. The proposed portable microsensor significantly contributes to aqueous inspection, subsequently creating a highly value-added technology for chemical sensors and microsystems.

scholarly journals Large-Volume Liquid Scintillation Counting of Carbon-14

Radiocarbon ◽  
1980 ◽  
Vol 22 (2) ◽  
pp. 417-427 ◽  
Author(s):  
Lorenz Eichinger ◽  
Werner Rauert ◽  
Josef Salvamoser ◽  
Manfred Wolf
Keyword(s):  
Detection Limit ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Measuring Chamber ◽  
Carbon 14 ◽  
Experimental Detection ◽  
Scintillation Solution ◽  
Special Measuring ◽  
Experimental Detection Limit

Efforts have been undertaken to further improve the relatively simple technique of low-level liquid scintillation counting of 14C. Two different approaches have been made. By synthesizing more benzene for 14C measurement than usual (with up to 19.5g of carbon) an experimental detection limit of about 0.1 percent modern has been achieved (97.5% confidence level, 1000 min). Absorption of CO2 with up to 5.3g of carbon in 160ml of an absorbent-scintillation solution and counting in a special measuring chamber resulted in an experimental detection limit of about 1 percent modern, with the sample preparation taking only 1 hour. The detection limits achieved by the two techniques correspond to 14C ages of about 55,000 and 35,000 years BP, respectively.

Sensitivity and detection limit analysis of silicon nanowire bio(chemical) sensors

2015 ◽  
Vol 209 ◽  
pp. 486-489 ◽  
Author(s):  
Songyue Chen ◽  
Albert van den Berg ◽  
Edwin T. Carlen
Keyword(s):  
Detection Limit ◽  
Chemical Sensors ◽  
Limit Analysis ◽  
Silicon Nanowire

Do Small Bubbles Follow Stokes Law?

2002 ◽  
Author(s):  
Denis Rodrigue
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Gas Bubbles ◽  
Air Bubbles ◽  
Hydrodynamic Conditions ◽  
The Past ◽  
Surface Active ◽  
Balance Of Forces ◽  
Small Bubbles ◽  
Rigid Interface

The motion of gas bubbles in a liquid medium is known to be affected by the presence of surface active molecules which modify the hydrodynamic conditions prevailing at the gas-liquid interface. In the past, gas bubbles rising in aqueous solutions have been said to follow Stokes law (rigid interface). In this work, we present some theoretical calculations and experimental data on the influence of surfactants for the motion of air bubbles rising in non-Newtonian solutions. It is shown that the rheology of the system introduces a complex balance of forces acting on the bubble.

Expansion of Gas Bubbles by Nitrous Oxide and Xenon

2006 ◽  
Vol 104 (2) ◽  
pp. 299-302 ◽  
Author(s):  
Rodrigo Benavides ◽  
Mervyn Maze ◽  
Nicholas P. Franks
Keyword(s):  
Aqueous Solution ◽  
Nitrous Oxide ◽  
Cardiopulmonary Bypass ◽  
Bypass Surgery ◽  
Gas Bubbles ◽  
Oxygen Mixture ◽  
Air Bubbles ◽  
Initial Size ◽  
Cardiopulmonary Bypass Surgery ◽  
Flowing Solution

Background Nitrous oxide is well known to expand gas bubbles trapped in enclosed spaces and is contraindicated in situations where this may occur. Xenon, an anesthetic gas with similar physical properties to nitrous oxide, is also likely to expand gas bubbles, and it has been predicted that microbubbles in the circulation may expand dramatically when exposed to xenon. Because of the possibility that xenon will be used during cardiopulmonary bypass surgery, a procedure that is likely to introduce microbubbles into the circulation, the authors reinvestigated the extent to which xenon expands gas bubbles in aqueous solution. Methods Gas bubbles of either air or oxygen were formed in an aqueous solution, and their size was monitored using optical microscopy when they were exposed to a rapidly flowing solution of xenon, nitrous oxide, or a xenon-oxygen mixture. Results Both nitrous oxide and xenon rapidly expanded air bubbles, although nitrous oxide caused a much larger expansion. The observed expansion was not greatly dependent on the initial size of the bubble but was significantly greater at lower temperatures. Under conditions relevant to cardiopulmonary bypass surgery (50% xenon-50% oxygen, 30 degrees C), the increase in diameter was modest (9.7 +/- 0.8%). Conclusions Although xenon does expand small air and oxygen bubbles, the extent to which this occurs under clinically relevant conditions of concentration and temperature is modest.

Hyperbaric oxygen may reduce gas bubbles in decompressed prawns by eliminating gas nuclei

2002 ◽  
Vol 92 (6) ◽  
pp. 2596-2599 ◽  
Author(s):  
Yehuda Arieli ◽  
Ran Arieli ◽  
Amit Marx
Keyword(s):  
Hyperbaric Oxygen ◽  
Decompression Sickness ◽  
Gas Bubbles ◽  
Crossover Design ◽  
Air Bubbles ◽  
Normobaric Oxygen ◽  
Bubble Volume ◽  
Metabolic Role ◽  
Oxygen Profile

It is accepted that gas bubbles grow from preexisting gas nuclei in tissue. The possibility of eliminating gas nuclei may be of benefit in preventing decompression sickness. In the present study, we examined the hypothesis that hyperbaric oxygen may replace the resident gas in the nuclei with oxygen and, because of its metabolic role, eliminate the nuclei themselves. After pretreatment with oxygen, prawns were 98% saturated with nitrogen before explosive decompression at 30 m/min. Ten transparent prawns were exposed to four experimental profiles in a crossover design: 1) 10-min compression to 203 kPa with air; 2) 10-min compression with oxygen; 3) 10-min compression with oxygen to 203 kPa followed by 12 min air at 203 kPa; and 4) 10 min in normobaric oxygen followed by compression to 203 kPa with air. Bubbles were measured after explosive decompression. We found that pretreatment with hyperbaric oxygen ( profile C) significantly reduces the number of bubbles and bubble volume. We suggest that hyperbaric oxygen eliminates bubble nuclei in the prawn.

scholarly journals Cerebral Air Embolism after Central Venous Catheter Self-Extraction

2014 ◽  
Vol 41 (2) ◽  
pp. 267-269 ◽  
Author(s):  
Aasim Hasany ◽  
Jonathan Butler ◽  
Andrew Leung ◽  
G. Bryan Young
Keyword(s):  
Central Venous Catheter ◽  
Gas Bubbles ◽  
Air Embolism ◽  
Venous Catheter ◽  
Air Bubbles ◽  
Central Venous Catheter Insertion ◽  
Retrograde Flow ◽  
Central Venous ◽  
Cerebral Air Embolism ◽  
Cardiac Defects

Cerebral air embolism associated with central venous catheter insertion and removal is a rare but serious complication. There are many hypotheses on how air bubbles might be transported from the venous system to intracranial vessels. The literature has described how intra-cardiac defects transpulmonary passage and even retrograde flow of gas bubbles can explain this phenomenon. We present a case that illustrates the devastating effects of cerebral air embolism after a patient selfextracted his central venous catheter.

scholarly journals The cataphoresis of gas bubbles in water

1924 ◽  
Vol 106 (737) ◽  
pp. 315-340 ◽  
Keyword(s):  
Electric Current ◽  
Capillary Tube ◽  
Gas Bubbles ◽  
Air Bubbles ◽  
Glass Capillary ◽  
Capillary Tubes ◽  
Quantitative Results ◽  
A Current

The first observations on the electrification of liquid-gas interfaces were ode by Quincke (‘ Pogg. Ann.,’ vol. 113, p. 513 (1861)). He found that the sage of an electric current through a capillary tube containing water caused movement of the surface of the latter, which was exactly proportional to quantity of electricity passed. He also noted that the passage of a current though a liquid containing gas bubbles caused the latter to move towards an electrode. In his experiments the motion of these air bubbles was inestigated in narrow glass capillary tubes, and the bubbles were found to move towards the anode when submerged in water, but towards the cathode en the water was replaced by turpentine. Further work on the electrification of gas bubbles was carried out by Taggart (‘ Phil. Mag.,’ vol. 27, p. 297 (1914) ; vol. 28, p. 367 (1914)). The rrow capillary tubes used by Quincke for this purpose are not very satisfactory, ache bubble tends to stick to the sides of the tube, making it almost impossible obtain quantitative results.

scholarly journals Gas Bubbles as Oceanographic Tracers

2010 ◽  
Vol 27 (1) ◽  
pp. 241-245 ◽  
Author(s):  
Burkard Baschek ◽  
David M. Farmer
Keyword(s):  
British Columbia ◽  
Gas Bubbles ◽  
Air Bubbles ◽  
Tidal Front ◽  
Echo Sounder

Abstract Air bubbles can be used as oceanographic tracers that indicate the strength of a downwelling current by which they are subducted. In a tidal front in the Fraser Estuary, British Columbia, Canada, vertical currents of up to 0.70 m s−1 subduct bubbles to depths of more than 160 m. Echo sounder measurements are compared with simultaneous ADCP current measurements and are interpreted with a bubble model by S. A. Thorpe, yielding an estimate of the vertical current that carries the bubbles to the depth of measurement.

scholarly journals Engineering transcription factor BmoR mutants for constructing multifunctional alcohol biosensors

2021 ◽  
Author(s):  
Tong Wu ◽  
Zhenya Chen ◽  
Cuiying Zhang ◽  
Yi-Xin Huo
Keyword(s):  
Transcription Factor ◽  
Detection Limit ◽  
Value Added ◽  
Signal Molecule ◽  
Higher Alcohol ◽  
Detection Range ◽  
Small Molecule Ligands ◽  
Low Sensitivity ◽  
In Situ Detection

Native transcription factor based biosensors (TFBs) have the potential for in situ detection of value added chemicals or byproducts. However, their industrial application is limited by their ligand promiscuity, low sensitivity, and narrow detection range. Alcohols exhibit similar structures, and no reported TFB can distinguish a specific alcohol from its analogs. Here, we engineered an alcohol regulated transcription factor,BmoR,and obtained various mutants with remarkable properties. For example, the generated signal molecule specific BmoRs could distinguish the constitutional isomers n butanol and isobutanol, with insensitivity up to an ethanol concentration of 800 mM (36.9 g/L). Linear detection of 0 60 mM of a specific higher alcohol could be achieved in the presence of up to 500 mM (23.0 g/L) ethanol as background noise. Notably, two mutants with raised outputs and over 107 fold higher sensitivity, and one mutant with an increased upper detection limit (14.8 g/L nbutanol or isobutanol) were screened out. Using BmoR as an example, this study systematically explored the ultimate detection limit of a TFB towards its small molecule ligands, paving the way for in situ detection in the biofuel and wine industries.

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

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