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Chemistry

Chemical engineering and processing

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Displaying 201 - 225 of 405

Reproducibility and Robustness of a Real-Time Microfluidic Cell Toxicity Assay

May 15, 2011
Author(s)
Gregory A. Cooksey, John T. Elliott, Anne L. Plant
Numerous opportunities exist to apply microfluidic technology to high-throughput and high-content cell-based assays. However, maximizing the value of these assays for drug discovery, screening or toxicity evaluation, for example, will require validation of

Micro Cryogenic Coolers for IR Imaging

April 29, 2011
Author(s)
Ryan J. Lewis, Yunda Wang, Jill Cooper, Mu Hong Lin, Victor M. Bright, Yung-Cheng Lee, Peter E. Bradley, Ray Radebaugh, Marcia L. Huber
Joule-Thomson micro cryogenic coolers (MCCs) are a preferred approach for small and low power cryocoolers. With the same heat lift, MCC's power input can be only 1/10 of a thermoelectric cooler's input, and MCC's size can be only 1/10 of a Stirling cooler

Present Estimates of the Differences Between Thermodynamic Temperatures and the ITS-90

January 29, 2011
Author(s)
Joachim Fischer, M. DePodesta, K. D. Hill, Michael R. Moldover, Laurent Pitre, R. Rusby, Peter Steur, Osamu Tamura, R. White, L. Wolber
In 2005, the Consultative Committee for Thermometry (CCT) recommended the creation of a Mise en pratique for the definition of the kelvin and envisioned that future versions of the Mise en pratique would recommend values of the differences between

Microfluidics Measurements of Interfacial Rheology

January 18, 2011
Author(s)
Jeffrey D. Martin, Joie N. Marhefka, Kalman D. Migler, Steven D. Hudson
The bulk properties and structural characteristics of emulsions arise substantially from their interfacial rheology, which depends strongly on surfactant mass transfer and its coupling to flow. Typical methods used to measure such properties often employ

Model for Transient Behavior of Pulse Tube Cryocooler

January 1, 2011
Author(s)
Gershon Grossman, Peter E. Bradley, Michael A. Lewis, Ray Radebaugh
This article describes an investigation of the transient behavior of a small (2.0 W at 85 K) Pulse Tube cryocooler operating at 120 Hz with an average pressure of 3.5 MPa, capable of relatively fast cool-down to about 60 K. In a series of experiments, the

Microstructure and hydrogen bonding in water-acetonitrile mixtures

November 19, 2010
Author(s)
Raymond D. Mountain
The connection between hydrogen bonding between water and acetonitrile in determining the microheterogeneity of the liquid mixture is examined using NPT molecular dynamics simulations. Mixtures for six, rigid, three-site models for acetonitrile and one

The Roles of the Mise en Pratique for the Definition of the Kelvin

October 16, 2010
Author(s)
Dean C. Ripple, Richard Davis, Bernd Fellmuth, Joachim Fischer, Graham Machin, Terry Quinn, Peter Steur, Osamu Tamura, David R. White
The mise en pratique (“practical realization”) for the definition of the kelvin (MeP-K) was created by the Consultative Committee for Thermometry (CCT) in 2006 to give practitioners of thermometry a guide to the realization of the kelvin, in accord with

Bilateral Comparison Confirms NIMs and NISTs Gas Flow Capabilities

October 15, 2010
Author(s)
Aaron N. Johnson, CHUNHUI LI
The bilateral comparison between NIM and NIST for gas flow was conducted from June 2008 to October 2009. Two critical flow venturis (CFVs) with nominal throat diameters of 10 mm and 20 mm, respectively, were selected as transfer standards. The CFVs were

Properties for Accurate Gas Flow Measurements

October 15, 2010
Author(s)
John D. Wright
Accurate gas properties are needed to take full advantage of the low uncertainties provided by NIST’s Gas Flow Calibration Services. If a flowmeter user and NIST use different values for these properties (molecular mass, compressibility, density, viscosity

Separation and Metrology of Nanoparticles by Nanofluidic Size Exclusion

August 11, 2010
Author(s)
Samuel M. Stavis, Jon C. Geist, Michael Gaitan
A nanofluidic approach to the separation and metrology of nanoparticles is demonstrated. Advantages of this approach include nanometer-scale resolution, nanometer-scale to submicrometer-scale range, mitigation of hydrodynamic and diffusional limitations to

Using Microfluidic Channels to Determine ZThe Quantitative Permittivity of Nanoliter Fluid Volumes from 50 MHz TO 40 GHz USING MICROFLUIDIC CHANNELS TO DETERMINE THE QUANTITATIVE PERMITTIVITY OF NANOLITER FLUID VOLUMES FROM 50 MHZ TO 40 GHZ

July 30, 2010
Author(s)
James C. Booth, Nathan D. Orloff, Xiaoli Lu, Yu Y. Wang, Eduard Rocas, Jordi Mateu, Juan C. Collado Gomez, Michael D. Janezic
We describe the development of coplanar waveguide measurement structures integrated with microfluidic channels in order to rapidly determine the broadband dielectric properties of nanoliter volumes of fluids, fluid mixtures, and colloids over the range of

Standard Photoacoustic Spectrometer: Model and Validation using O2 A-Band Spectra

June 30, 2010
Author(s)
Keith A. Gillis, Daniel K. Havey, Joseph T. Hodges
We model and measure the absolute response of an intensity-modulated photoacoustic spectrometer comprising a 10 cm long resonator and having a Q-factor of approximately 30. We present a detailed theoretical analysis of the system and predict its response

Compact and Distributed Modeling of Cryogenic Bulk MOSFET Operation

June 1, 2010
Author(s)
Akin Akturk, M. Holloway, S. Potbhare, David J. Gundlach, B Li, Neil Goldsman, M Peckerar, Kin P. Cheung
We have developed compact and physics-based distributed numerical models for cryogenic bulkMOSFET operation down to 20 K to advance simulation and first-pass design of device and circuit operation at low temperatures. To achieve this, we measured and

Feasibility of an Accurate Dynamic Standard for Water Flow

June 1, 2010
Author(s)
Iosif I. Shinder, Michael R. Moldover
We used NIST's primary water flow standard to study the feasibility of accurately determining mass flow rates m dot of water "dynamically," that is from the time derivative of the weight W of the collection tank: m dot,dynamic = (dW/dt)/g. When data for a
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