A Microfabricated Device for the Characterization of Biological Entities

2001 ◽  
Vol 679 ◽  
Author(s):  
H. Chang ◽  
A. Ikram ◽  
M. Young ◽  
F. Kosari ◽  
G. Vasmatzis ◽  
...  
Keyword(s):  
Current Flow ◽  
Ionic Current ◽  
Listeria Innocua ◽  
Test Case ◽  
Micro Machining ◽  
Initial Test ◽  
Buffer Solutions ◽  
Effective Mobility ◽  
Biological Entities

ABSTRACTA micro-fabricated pore is constructed and tested so that it can be used to characterize biological entities. The pore is prepared by bulk micro-machining of a silicon wafer. An oxide coated silicon diaphragm with the pore is placed between two chambers containing ionic buffer solutions to mimic a bilayer system. If a voltage is applied across the pore, electrophoretic passage of charged entities can be electrically detected through changes in the ionic current flow. When the entities traverse the pore, the ionic current is blocked and a decrease in the current can be observed. As an initial test case, negatively charged polystyrene beads which were 2.38μm in diameter, were electrophoretically driven across the pore. Then the bacteriumListeria innocua, suspended in Tris-glycine buffer, was also electrophoretically driven through the pore and its effective mobility was extracted. The device can also be used to study the interactions between organisms and the micro-fabricated surfaces. Work is continuing to scale the pore to the sub-100A range to be used for characterization and possible sequencing of single molecules such as DNA.

A Numerical Investigation Into the Interaction Between Current Flow and Fuel Consumption in a Segmented-in-Series Tubular SOFC

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
B. A. Haberman ◽  
A. J. Marquis
Keyword(s):  
Density Distribution ◽  
Fuel Consumption ◽  
Current Density ◽  
Current Flow ◽  
Flow Direction ◽  
Ionic Current ◽  
Leading Edge ◽  
Current Density Distribution ◽  
Fuel Flow ◽  
In Series

A typical segmented-in-series tubular solid oxide fuel cell (SOFC) consists of flattened ceramic support tubes with rows of electrochemical cells fabricated on their outer surfaces connected in series. It is desirable to design this type of SOFC to operate with a uniform electrolyte current density distribution to make the most efficient use of the available space and possibly to help minimize the onset of cell component degradation. Predicting the electrolyte current density distribution requires an understanding of the many physical and electrochemical processes occurring, and these are simulated using the newly developed SOHAB multiphysics computer code. Of particular interest is the interaction between the current flow within the cells and the consumption of fuel from an adjacent internal gas supply channel. Initial simulations showed that in the absence of fuel consumption, ionic current tends to concentrate near the leading edge of each electrolyte. Further simulations that included fuel consumption showed that the choice of fuel flow direction can have a strong effect on the current flow distribution. The electrolyte current density distribution is biased toward the upstream fuel flow direction because ionic current preferentially flows in regions rich in fuel. Thus the correct choice of fuel flow direction can lead to more uniform electrolyte current density distributions, and hence it is an important design consideration for tubular segmented-in-series SOFCs. Overall, it was found that the choice of fuel flow direction has a negligible effect on the output voltage of the fuel cells.

The History of Meter

2012 ◽  
Author(s):  
Meredith Martin
Keyword(s):  
English Language ◽  
Test Case ◽  
Methodological Framework ◽  
Anglo Saxon ◽  
Gerard Manley Hopkins ◽  
English Poet ◽  
History Of ◽  
Material History ◽  
English Culture

This chapter sets out the book's historical and methodological framework. Despite the modernist characterization of Victorian tradition as unified and steadfast, the various approaches to Victorian meter in English histories, grammars, and metrical studies reveal ideologically charged histories of English culture, often presented as Roman or Anglo-Saxon. Gerard Manley Hopkins was himself a mediator between various metrical discourses and theories. As a Catholic priest who taught the classics and an English poet who attempted to valorize the material history of the English language in his syntax and through his use of sprung rhythm, Hopkins is a test case for the personal and national ideologies of English meter.

scholarly journals Synthesis and Characterization of Chemically Cross-Linked CMC/Acrylamide Hydrogels

2020 ◽  
Vol 32 (5) ◽  
pp. 1109-1115
Author(s):  
Shivakumara Lachakkal Rudrappa ◽  
Sudhir Ramaswamy Iliger ◽  
Demappa Thippaiah
Keyword(s):  
Room Temperature ◽  
Aluminum Sulfate ◽  
Ammonium Persulfate ◽  
Sem Analysis ◽  
Cross Linking ◽  
Swelling Behaviour ◽  
Buffer Solutions ◽  
Aluminium Sulfate ◽  
Chemical Cross Linking

Carboxymethyl cellulose/poly(acrylamide) (CMC/Amm) hydrogels were synthesized by the chemical cross-linking method. Ammonium persulfate used as an initiator, while aluminium sulfate used as a cross-linking agent. The structure and morphology of the hydrogels were characterized by FTIR and scanning electron microscopy (SEM) analysis. The swelling behaviour of the hydrogels can be studied by using acids (CH3COOH, HCl and HClO4) and also in the pH of the buffer solutions at different temperature (room temperature, 30 and 37 ºC) was studied. Swelling of hydrogels increased with an increase in the concentration of aluminum sulfate up to 20 %, above 20 % it has found to be decreased. The effect of four series of cationic different concentrated salt solutions on the swelling had found to be the following order K+ > Na+ > Ca2+ > Mg2+.

scholarly journals Physical characterization of 2020 AV2, the first known asteroid orbiting inside Venus orbit

2020 ◽  
Vol 496 (3) ◽  
pp. 3572-3581 ◽  
Author(s):  
M Popescu ◽  
J de León ◽  
C de la Fuente Marcos ◽  
O Vaduvescu ◽  
R de la Fuente Marcos ◽  
...  
Keyword(s):  
Spectral Band ◽  
Absolute Magnitude ◽  
High Energy ◽  
Test Case ◽  
Optical Telescope ◽  
Small Bodies ◽  
William Herschel ◽  
Near Earth Asteroids ◽  
Innermost Region

ABSTRACT The first known asteroid with the orbit inside that of Venus is 2020 AV2. This may be the largest member of a new population of small bodies with the aphelion smaller than 0.718 au, called Vatiras. The surface of 2020 AV2 is being constantly modified by the high temperature, by the strong solar wind irradiation that characterizes the innermost region of the Solar system, and by high-energy micrometeorite impacts. The study of its physical properties represents an extreme test-case for the science of near-Earth asteroids. Here, we report spectroscopic observations of 2020 AV2 in the 0.5–1.5-μm wavelength interval. These were performed with the Nordic Optical Telescope and the William Herschel Telescope. Based on the obtained spectra, we classify 2020 AV2 as a Sa-type asteroid. We estimate the diameter of this Vatira to be $1.50_{-0.65}^{+1.10}$ km by considering the average albedo of A-type and S-complex asteroids ($p_V=0.23_{-0.08}^{+0.11}$), and the absolute magnitude (H = 16.40 ± 0.78 mag). The wide spectral band around 1 μm shows the signature of an olivine-rich composition. The estimated band centre BIC = 1.08 ± 0.02 μm corresponds to a ferroan olivine mineralogy similar to that of brachinite meteorites.

FlakyLoc: Flakiness Localization for Reliable Test Suites in Web Applications

2020 ◽  
Author(s):  
Jesús Morán ◽  
Cristian Augusto ◽  
Antonia Bertolino ◽  
Claudio De La Riva ◽  
Javier Tuya
Keyword(s):  
Environmental Factors ◽  
Web Application ◽  
Web Applications ◽  
Test Case ◽  
Test Cases ◽  
Root Cause ◽  
Test Execution ◽  
Fine Grain ◽  
Asynchronous Communications

Web application testing is a great challenge due to the management of complex asynchronous communications, the concurrency between the clients-servers, and the heterogeneity of resources employed. It is difficult to ensure that a test case is re-running in the same conditions because it can be executed in undesirable ways according to several environmental factors that are not easy to fine-grain control such as network bottlenecks, memory issues or screen resolution. These environmental factors can cause flakiness, which occurs when the same test case sometimes obtains one test outcome and other times another outcome in the same application due to the execution of environmental factors. The tester usually stops relying on flaky test cases because their outcome varies during the re-executions. To fix and reduce the flakiness it is very important to locate and understand which environmental factors cause the flakiness. This paper is focused on the localization of the root cause of flakiness in web applications based on the characterization of the different environmental factors that are not controlled during testing. The root cause of flakiness is located by means of spectrum-based localization techniques that analyse the test execution under different combinations of the environmental factors that can trigger the flakiness. This technique is evaluated with an educational web platform called FullTeaching. As a result, our technique was able to locate automatically the root cause of flakiness and provide enough information to both understand it and fix it.

Characterization of two Listeria innocua chitinases of different sizes that were expressed in Escherichia coli

2016 ◽  
Vol 100 (18) ◽  
pp. 8031-8041 ◽  
Author(s):  
Shotaro Honda ◽  
Satoshi Wakita ◽  
Yasusato Sugahara ◽  
Masao Kawakita ◽  
Fumitaka Oyama ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Innocua

A Numerical Investigation Into the Use of Patterned Electrodes in a Segmented-in-Series Tubular SOFC

2008 ◽  
Author(s):  
B. A. Haberman ◽  
G. Bortuzzo ◽  
A. J. Marquis
Keyword(s):  
Current Flow ◽  
Ionic Current ◽  
Current Collector ◽  
Computer Code ◽  
Flow Path ◽  
High Conductivity ◽  
Cell Performance ◽  
Additional Layer ◽  
Ceramic Support ◽  
In Series

A typical segmented-in-series tubular SOFC consists of flattened ceramic support tubes with rows of electrochemical cells fabricated on their outer surfaces and connected in series along their length. In this design, the electrical resistance of the long current flow path is minimised by using high conductivity electrodes. Therefore the resistance of the cathode, which typically has a low electrical conductivity, is reduced by fabricating an additional high conductivity current collector layer. This study is concerned with investigating the design of this additional layer using the newly developed SOHAB multi-physics computer code. Initial simulations identified the optimum thickness of a uniform current collector with respect to cell performance and component cost. However, it was found that this uniform layer causes ionic current to concentrate near the edges of the electrolyte, potentially enhancing cell degradation. Further simulations investigated whether a patterned current collector could be designed to control the current flow within the cell and reduce this detrimental effect. It was found that, for an identical thickness collector layer, a patterned design could reduce spatial variations of ionic current by a factor of over two with a negligible effect on cell performance. Therefore, patterned current collectors represent a means to control the current flow path within a segmented-in-series cell and further improve its performance.

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