RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Apr 2012

Volume 83, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Rev. Sci. Instrum. 83, 041101 (2012); http://dx.doi.org/10.1063/1.3697599 (19 pages)

Michael A. Duncan

The laser vaporization cluster source in the "cutaway" configuration. The sample rod is mounted from above with a flexible nylon screw in a holding block. The pulsed gas valve is mounted in the stainless steel can (left) and the skimmer is mounted on the opposite wall.

Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds
back to top Microscopy and Imaging

Stereoscopic high-speed imaging using additive colors

Georgy N. Sankin, David Piech, and Pei Zhong

Rev. Sci. Instrum. 83, 043701 (2012); http://dx.doi.org/10.1063/1.3697747 (3 pages)

Online Publication Date: 6 April 2012

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
An experimental system for digital stereoscopic imaging produced by using a high-speed color camera is described. Two bright-field image projections of a three-dimensional object are captured utilizing additive-color backlighting (blue and red). The two images are simultaneously combined on a two-dimensional image sensor using a set of dichromatic mirrors, and stored for off-line separation of each projection. This method has been demonstrated in analyzing cavitation bubble dynamics near boundaries. This technique may be useful for flow visualization and in machine vision applications.
Show PACS
47.80.Jk Flow visualization and imaging
47.55.dp Cavitation and boiling
47.55.D- Drops and bubbles

Three-dimensional transport imaging for the spatially resolved determination of carrier diffusion length in bulk materials

K. E. Blaine, D. J. Phillips, C. L. Frenzen, C. Scandrett, and N. M. Haegel

Rev. Sci. Instrum. 83, 043702 (2012); http://dx.doi.org/10.1063/1.3698090 (7 pages)

Online Publication Date: 6 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A contact-free optical technique is developed to enable a spatially resolved measurement of minority carrier diffusion length and the associated mobility-lifetime (μτ) product in bulk semiconductor materials. A scanning electron microscope is used in combination with an internal optical microscope and imaging charge-coupled device (CCD) to image the bulk luminescence from minority carrier recombination associated with one-dimensional excess carrier generation. Using a Green's function to model steady-state minority carrier diffusion in a three-dimensional half space, non-linear least squares analysis is then applied to extract values of carrier diffusion length and surface recombination velocity. The approach enables measurement of spatial variations in the μτ product with a high degree of spatial resolution.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Dual resonance excitation system for the contact mode of atomic force microscopy

M. Kopycinska-Müller, A. Striegler, R. Schlegel, N. Kuzeyeva, B. Köhler, and K.-J. Wolter

Rev. Sci. Instrum. 83, 043703 (2012); http://dx.doi.org/10.1063/1.3702799 (8 pages)

Online Publication Date: 12 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose an improved system that enables simultaneous excitation and measurements of at least two resonance frequency spectra of a vibrating atomic force microscopy (AFM) cantilever. With the dual resonance excitation system it is not only possible to excite the cantilever vibrations in different frequency ranges but also to control the excitation amplitude for the individual modes. This system can be used to excite the resonance frequencies of a cantilever that is either free of the tip-sample interactions or engaged in contact with the sample surface. The atomic force acoustic microscopy and principally similar methods utilize resonance frequencies of the AFM cantilever vibrating while in contact with the sample surface to determine its local elastic modulus. As such calculation demands values of at least two resonance frequencies, two or three subsequent measurements of the contact resonance spectra are necessary. Our approach shortens the measurement time by a factor of two and limits the influence of the AFM tip wear on the values of the tip-sample contact stiffness. In addition, it allows for in situ observation of processes transpiring within the AFM tip or the sample during non-elastic interaction, such as tip fracture.
Show PACS
07.79.Lh Atomic force microscopes
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography

Electrical capacitance tomography using an accelerated proximal gradient algorithm

Qian Xue, Huaxiang Wang, Ziqiang Cui, and Chengyi Yang

Rev. Sci. Instrum. 83, 043704 (2012); http://dx.doi.org/10.1063/1.3703306 (7 pages)

Online Publication Date: 16 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Image reconstruction in electrical capacitance tomography requires a solution of an ill-posed inverse problem. This paper applies an accelerated proximal gradient (APG) singular value thresholding algorithm, which is originally proposed for the matrix completion problem, to image two-phase flow. Aiming to improve the image quality, a nuclear norm-based regularization technique is adopted to treat the ill-posedness of the inverse problem, and a simple updating technique is used to update the sensitivity matrix. Both typical and complicated distributions (e.g., “sun-rise” and cross-shape), have been examined based on a 16-electrode configuration. The results showed that the APG algorithm with updated sensitivity matrix could produce higher quality images when compared to the algorithm based on the typical sensitivity matrix. Both simulation and experiment results indicate that the algorithm developed has been able to achieve good quality reconstructed images with relativity fast computation speed for the cases tested in this paper.
Show PACS
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
42.30.Wb Image reconstruction; tomography
02.30.Zz Inverse problems
02.60.-x Numerical approximation and analysis

Compact, low power radio frequency cavity for femtosecond electron microscopy

A. Lassise, P. H. A. Mutsaers, and O. J. Luiten

Rev. Sci. Instrum. 83, 043705 (2012); http://dx.doi.org/10.1063/1.3703314 (10 pages) | Cited 1 time

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Reported here is the design, construction, and characterization of a small, power efficient, tunable dielectric filled cavity for the creation of femtosecond electron bunches in an existing electron microscope without the mandatory use of femtosecond lasers. A 3 GHz pillbox cavity operating in the TM110 mode was specially designed for chopping the beam of a 30 keV scanning electron microscope. The dielectric material used is ZrTiO4, chosen for the high relative permittivity (ɛr = 37 at 10 GHz) and low loss tangent (tan δ = 2 × 10−4). This allows the cavity radius to be reduced by a factor of six, while the power consumption is reduced by an order of magnitude compared to a vacuum pillbox cavity. These features make this cavity ideal as a module for existing electron microscopes, and an alternative to femtosecond laser systems integrated with electron microscopes.
Show PACS
42.79.-e Optical elements, devices, and systems
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
06.60.Jn High-speed techniques (microsecond to femtosecond)

18/20 T high magnetic field scanning tunneling microscope with fully low voltage operability, high current resolution, and large scale searching ability

Quanfeng Li, Qi Wang, Yubin Hou, and Qingyou Lu

Rev. Sci. Instrum. 83, 043706 (2012); http://dx.doi.org/10.1063/1.3703568 (5 pages) | Cited 1 time

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a home-built 18/20 T high magnetic field scanning tunneling microscope (STM) featuring fully low voltage (lower than ±15 V) operability in low temperatures, large scale searching ability, and 20 fA high current resolution (measured by using a 100 GOhm dummy resistor to replace the tip-sample junction) with a bandwidth of 3.03 kHz. To accomplish low voltage operation which is important in achieving high precision, low noise, and low interference with the strong magnetic field, the coarse approach is implemented with an inertial slider driven by the lateral bending of a piezoelectric scanner tube (PST) whose inner electrode is axially split into two for enhanced bending per volt. The PST can also drive the same sliding piece to inertial slide in the other bending direction (along the sample surface) of the PST, which realizes the large area searching ability. The STM head is housed in a three segment tubular chamber, which is detachable near the STM head for the convenience of sample and tip changes. Atomic resolution images of a graphite sample taken under 17.6 T and 18.0001 T are presented to show its performance.
Show PACS
07.79.Cz Scanning tunneling microscopes

A method to provide rapid in situ determination of tip radius in dynamic atomic force microscopy

Sergio Santos, Li Guang, Tewfik Souier, Karim Gadelrab, Matteo Chiesa, and Neil H. Thomson

Rev. Sci. Instrum. 83, 043707 (2012); http://dx.doi.org/10.1063/1.4704376 (11 pages) | Cited 10 times

Online Publication Date: 24 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We provide a method to characterize the tip radius of an atomic force microscopy in situ by monitoring the dynamics of the cantilever in ambient conditions. The key concept is that the value of free amplitude for which transitions from the attractive to repulsive force regimes are observed, strongly depends on the curvature of the tip. In practice, the smaller the value of free amplitude required to observe a transition, the sharper the tip. This general behavior is remarkably independent of the properties of the sample and cantilever characteristics and shows the strong dependence of the transitions on the tip radius. The main advantage of this method is rapid in situ characterization. Rapid in situ characterization enables one to continuously monitor the tip size during experiments. Further, we show how to reproducibly shape the tip from a given initial size to any chosen larger size. This approach combined with the in situ tip size monitoring enables quantitative comparison of materials measurements between samples. These methods are set to allow quantitative data acquisition and make direct data comparison readily available in the community.
Show PACS
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.79.Lh Atomic force microscopes

A gantry-based tri-modality system for bioluminescence tomography

Han Yan, Yuting Lin, William C. Barber, Mehmet Burcin Unlu, and Gultekin Gulsen

Rev. Sci. Instrum. 83, 043708 (2012); http://dx.doi.org/10.1063/1.3698295 (8 pages) | Cited 1 time

Online Publication Date: 25 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A gantry-based tri-modality system that combines bioluminescence (BLT), diffuse optical (DOT), and x-ray computed tomography (XCT) into the same setting is presented here. The purpose of this system is to perform bioluminescence tomography using a multi-modality imaging approach. As parts of this hybrid system, XCT and DOT provide anatomical information and background optical property maps. This structural and functional a priori information is used to guide and restrain bioluminescence reconstruction algorithm and ultimately improve the BLT results. The performance of the combined system is evaluated using multi-modality phantoms. In particular, a cylindrical heterogeneous multi-modality phantom that contains regions with higher optical absorption and x-ray attenuation is constructed. We showed that a 1.5 mm diameter bioluminescence inclusion can be localized accurately with the functional a priori information while its source strength can be recovered more accurately using both structural and the functional a priori information.
Show PACS
42.30.Wb Image reconstruction; tomography

Wide-band acousto-optic deflectors for large field of view two-photon microscope

Runhua Jiang, Zhenqiao Zhou, Xiaohua Lv, and Shaoqun Zeng

Rev. Sci. Instrum. 83, 043709 (2012); http://dx.doi.org/10.1063/1.4705972 (5 pages)

Online Publication Date: 26 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58–2.12 μm and 2.17–3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV.
Show PACS
42.79.Jq Acousto-optical devices
42.79.Fm Reflectors, beam splitters, and deflectors
07.60.Pb Conventional optical microscopes

Complementary cellophane optic gate and its use for a 3D iPad without glasses

K. Iizuka

Rev. Sci. Instrum. 83, 043710 (2012); http://dx.doi.org/10.1063/1.4705734 (8 pages)

Online Publication Date: 27 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A complementary cellophane optic gate was fabricated using a birefringent cellophane sheet. Previous versions of the optic gate required the retardance of the cellophane to be as close to 180° as possible throughout the entire visible wavelength range, which meant it was often difficult to find a cellophane sheet with the right thickness and dispersion characteristics to meet this requirement. The complementary optic gate reported in this paper has no restriction on the thickness, composition, or wavelength range of the cellophane sheet except that the cellophane must have some birefringence. Even with an arbitrary retardance, an extinction ratio of 5 × 10−3 was achieved at λ = 0.63 μm. The optic gate was used to convert an iPad into a 3D display without the need for the observer to wear glasses. The high extinction ratio of the optic gate resulted in a 3D display of supreme quality.
Show PACS
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.79.Kr Display devices, liquid-crystal devices
back to top Condensed Matter; Materials

A new pulsed laser deposition technique: Scanning multi-component pulsed laser deposition method

D. Fischer, G. F. de la Fuente, and M. Jansen

Rev. Sci. Instrum. 83, 043901 (2012); http://dx.doi.org/10.1063/1.3697861 (8 pages)

Online Publication Date: 3 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.15.Fg Pulsed laser ablation deposition

Thermal lens spectroscopy for the differentiation of biodiesel-diesel blends

M. Ventura, E. Simionatto, L. H. C. Andrade, and S. M. Lima

Rev. Sci. Instrum. 83, 043902 (2012); http://dx.doi.org/10.1063/1.3698002 (5 pages) | Cited 1 time

Online Publication Date: 3 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thermal lens (TL) spectroscopy was applied to biofuels to test its potential to distinguish diesel from biodiesel in blended fuels. Both the heat and mass diffusion effects observed using a TL procedure provide significant information about biodiesel concentrations in blended fuels. The results indicate that the mass diffusivity decreases 32% between diesel and the blend with 10% biodiesel added to the diesel. This simple TL procedure has the potential to be used for in loco analyses to certify the mixture and quality of biodiesel-diesel blends.
Show PACS
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques

A simple device for dielectric spectroscopy of polymers with temperature regulation close to 300 K based on a Peltier junction

A. Raihane, R. Tourbot, F. Ladieu, and D. L’Hôte

Rev. Sci. Instrum. 83, 043903 (2012); http://dx.doi.org/10.1063/1.3700217 (5 pages)

Online Publication Date: 9 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a simple thermostat device for performing dielectric spectroscopy measurements on polymers close to their glass transition temperature. By using a vacuum chamber containing a Peltier junction with its regulator, we show that a very simple setup yields a temperature accuracy which is good enough for accurate studies of polymer dielectric properties. This technique is also more cost effective than standard setups using cryogenic fluids.
Show PACS
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

A 30 T pulsed magnet with conical bore for synchrotron powder diffraction

J. Billette, F. Duc, P. Frings, M. Nardone, A. Zitouni, C. Detlefs, T. Roth, W. Crichton, J. E. Lorenzo, and G. L. J. A. Rikken

Rev. Sci. Instrum. 83, 043904 (2012); http://dx.doi.org/10.1063/1.3701830 (7 pages) | Cited 1 time

Online Publication Date: 9 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the design, construction, and operation of a horizontal field, 30 T magnet system with a conical bore optimized for synchrotron x-ray powder diffraction. The magnet offers ±31° optical access downstream of the sample, which allows to measure a sufficiently large number of Debye rings for an accurate crystal structure analysis. Combined with a 290 kJ generator, magnetic field pulses of 60 ms length were generated in the magnet, with a rise time of 4.1 ms and a repetition rate of 6 pulses/h at 30 T. The coil is mounted inside a liquid nitrogen bath. A liquid helium flow cryostat reaches into the coil and allows sample temperature between 5 and 250 K. The setup was used on the European Synchrotron Radiation Facility beamlines ID20 and ID06.
Show PACS
85.70.Ay Magnetic device characterization, design, and modeling

Femtosecond-laser-driven photoelectron-gun for time-resolved cathodoluminescence measurement of GaN

T. Onuma, Y. Kagamitani, K. Hazu, T. Ishiguro, T. Fukuda, and S. F. Chichibu

Rev. Sci. Instrum. 83, 043905 (2012); http://dx.doi.org/10.1063/1.3701368 (7 pages) | Cited 2 times

Online Publication Date: 11 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A rear-excitation femtosecond-laser-driven photoelectron gun (PE-gun) is developed for measuring time-resolved cathodoluminescence (TRCL) spectrum of wide bandgap materials and structures such as semiconductors and phosphors. The maximum quantum efficiency of a 20-nm-thick Au photocathode excited using a frequency-tripled Al2O3:Ti laser under a rear-excitation configuration is 3.6×10−6, which is a reasonable value for a PE-gun. When the distance between the front edge of the PE-gun and the observation point is 10 mm, the narrowest electron-beam (e-beam) diameter is 19 μm, which corresponds to one tenth of the laser-beam diameter and is comparable to the initial e-beam diameter of a typical W hair-pin filament of thermionic electron-gun. From the results of TRCL measurements on the freestanding GaN grown by the ammonothermal method and a GaN homoepitaxial film grown by metalorganic vapor phase epitaxy, overall response time for the present TRCL system is estimated to be 8 ps. The value is the same as that of time-resolved photoluminescence measurement using the same excitation laser pulses, meaning that the time-resolution is simply limited by the streak-camera, not by the PE-gun performance. The result of numerical simulation on the temporal e-beam broadening caused by the space-charge-effect suggests that the present PE-gun can be used as a pulsed e-beam source for spatio-time-resolved cathodoluminescence, when equipped in a scanning electron microscope.
Show PACS
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Fd III-V semiconductors
84.47.+w Vacuum tubes
78.47.D- Time resolved spectroscopy (>1 psec)

Application of ring method to measure surface tensions of liquids in high magnetic field

Chuanjun Li, Long Chen, and Zhongming Ren

Rev. Sci. Instrum. 83, 043906 (2012); http://dx.doi.org/10.1063/1.4704081 (5 pages) | Cited 1 time

Online Publication Date: 13 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The high-magnetic-field tensiometer (HMFT) has been developed to measure surface tensions of liquids in high magnetic field based on the ring method. The HMFT was composed of three parts: weighing system, liquid circulatory system, and supporting system. Some improvements for the conventional tensiometer were made in order to overcome the magnetic effects. The surface tension of acetone was measured using the HMFT. The results showed that the surface tension of acetone linearly varied with the magnetic field intensity and increased by 0.69 mN m−1 or 2.9% in the magnetic field of 10 T. The HMFT could better determine the surface tension of liquids with and without the magnetic field and it provided a simple and practical way to measure the surface tension of liquids at room temperature in a high magnetic field.
Show PACS
68.03.Cd Surface tension and related phenomena
06.30.Dr Mass and density

Lock-in detection for pulsed electrically detected magnetic resonance

Felix Hoehne, Lukas Dreher, Jan Behrends, Matthias Fehr, Hans Huebl, Klaus Lips, Alexander Schnegg, Max Suckert, Martin Stutzmann, and Martin S. Brandt

Rev. Sci. Instrum. 83, 043907 (2012); http://dx.doi.org/10.1063/1.4704837 (4 pages) | Cited 1 time

Online Publication Date: 20 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that in pulsed electrically detected magnetic resonance (pEDMR) signal modulation in combination with a lock-in detection scheme can reduce the low-frequency noise level by one order of magnitude and in addition removes the microwave-induced non-resonant background. This is exemplarily demonstrated for spin-echo measurements in phosphorus-doped silicon. The modulation of the signal is achieved by cycling the phase of the projection pulse used in pEDMR for the readout of the spin state.
Show PACS
76.30.-v Electron paramagnetic resonance and relaxation

Rheology of fluids measured by correlation force spectroscopy

Milad Radiom, Brian Robbins, Christopher D. F. Honig, John Y. Walz, Mark R. Paul, and William A. Ducker

Rev. Sci. Instrum. 83, 043908 (2012); http://dx.doi.org/10.1063/1.4704085 (14 pages) | Cited 1 time

Online Publication Date: 23 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe a method, correlation force spectrometry (CFS), which characterizes fluids through measurement of the correlations between the thermally stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss a major application: measurement of the rheological properties of fluids at high frequency and high spatial resolution. Use of CFS as a rheometer is validated by comparison between experimental data and finite element modeling of the deterministic ring-down of cantilevers using the known viscosity of fluids. The data can also be accurately fitted using a harmonic oscillator model, which can be used for rapid rheometric measurements after calibration. The method is non-invasive, uses a very small amount of fluid, and has no actively moving parts. It can also be used to analyze the rheology of complex fluids. We use CFS to show that (non-Newtonian) aqueous polyethylene oxide solution can be modeled approximately by incorporating an elastic spring between the cantilevers.
Show PACS
47.57.Qk Rheological aspects
47.11.Fg Finite element methods
02.70.Dh Finite-element and Galerkin methods
06.20.fb Standards and calibration
47.57.Ng Polymers and polymer solutions
47.50.Ef Measurements
back to top Chemistry

A resistive pyrolytic radical source for gas-surface reaction studies

David Y. Lee, Matthew M. Jobbins, and S. Alex Kandel

Rev. Sci. Instrum. 83, 044101 (2012); http://dx.doi.org/10.1063/1.3701370 (4 pages) | Cited 1 time

Online Publication Date: 5 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe a thermal gas cracker designed to produce low fluxes of gas-phase radicals for use in radical-surface reaction studies. A resistively heated thin piece of highly oriented pyrolytic graphite is used as the pyrolysis filament, with the major advantage that this material remains inert at high temperatures. The instrument is built within an existing titanium sublimation pump, which simplifies construction and allows for self-pumping of the radical source. Thermal generation of Cl atoms from Cl2 was chosen to test the effectiveness of the instrument. 35Cl and 37Cl were generated with a concomitant decrease in parent 70Cl2 and 72Cl2 species, as monitored by a residual gas analyzer. The cracking fraction of Cl2 as a function of cell temperature is reported, with nearly full conversion achieved at high temperature.
Show PACS
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Cf Atom and radical reactions; chain reactions; molecule-molecule reactions
back to top Biology and Medicine

A new device for performing reference point indentation without a reference probe

Daniel Bridges, Connor Randall, and Paul K. Hansma

Rev. Sci. Instrum. 83, 044301 (2012); http://dx.doi.org/10.1063/1.3693085 (8 pages)

Online Publication Date: 4 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Here we describe a novel, hand-held reference point indentation (RPI), instrument that is designed for clinical measurements of bone material properties in living patients. This instrument differs from previous RPI instruments in that it requires neither a reference probe nor removal of the periosteum that covers the bone, thus significantly simplifying its use in patient testing. After describing the instrument, we discuss five guidelines for optimal and reproducible results. These are: (1) the angle between the normal to the surface and the axis of the instrument should be less than 10°, (2) the compression of the main spring to trigger the device must be performed slowly (>1 s), (3) the probe tip should be sharper than 10 μm; however, a normalized parameter with a calibration phantom can correct for dull tips up to a 100 μm radius, (4) the ambient room temperature should be between 4 °C and 37 °C, and (5) the effective mass of the bone or material under test must exceed 1 kg, or if under 1 kg, the specimen should be securely anchored in a fixation device with sufficient mass (which is not a requirement of previous RPI instruments). Our experience is that a person can be trained with these guidelines in about 5 min and thereafter obtain accurate and reproducible results. The portability, ease of use, and minimal training make this instrument suitable to measure bone material properties in a clinical setting.
Show PACS
87.85.gp Mechanical systems
87.19.R- Mechanical and electrical properties of tissues and organs

A thermal study of cellular motility by optical time-resolved correlation

F. J. Sierra-Valdez, A. J. Cisneros-Mejorado, D. P. Sánchez Herrera, and J. C. Ruiz-Suárez

Rev. Sci. Instrum. 83, 044302 (2012); http://dx.doi.org/10.1063/1.3700248 (4 pages)

Online Publication Date: 4 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The study of motor properties of cells under appropriate physical-chemical conditions is a significant problem nowadays. The standard techniques presently used do not allow to evaluate neither large samples nor to control their thermodynamic conditions. In this work, we report a cell motility sensor based on an optical technique with a time-resolved correlation, adapted in a system able to study several samples simultaneously. Image correlation analysis is used to follow their temporal behavior. A wide variety of motile cells, such as archaea, bacteria, spermatozoa, and even contractile cells, can be studied using this technique. Here, we tested our technique with the study of sperm motility. In particular, both the sperm motility and its prevalence are studied under a temperature range from 0 to 37 °C. We found that incubation at 10 °C presents the lengthiest prevalence in motility and observed, for the first time, an interesting thermal reversibility behavior.
Show PACS
87.17.Jj Cell locomotion, chemotaxis
87.18.Gh Cell-cell communication; collective behavior of motile cells

Continuous-waveform constant-current isolated physiological stimulator

Mark R. Holcomb, Jack M. Devine, Rene Harder, and Veniamin Y. Sidorov

Rev. Sci. Instrum. 83, 044303 (2012); http://dx.doi.org/10.1063/1.3700977 (6 pages)

Online Publication Date: 6 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.
Show PACS
87.19.Hh Cardiac dynamics
87.19.R- Mechanical and electrical properties of tissues and organs
87.85.Ox Biomedical instrumentation and transducers, including micro-electro-mechanical systems (MEMS)

Development of a microbial high-throughput screening instrument based on elastic light scatter patterns

Euiwon Bae, Valery Patsekin, Bartek Rajwa, Arun K. Bhunia, Cheryl Holdman, V. Jo Davisson, E. Daniel Hirleman, and J. Paul Robinson

Rev. Sci. Instrum. 83, 044304 (2012); http://dx.doi.org/10.1063/1.3697853 (10 pages) | Cited 1 time

Online Publication Date: 12 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A microbial high-throughput screening (HTS) system was developed that enabled high-speed combinatorial studies directly on bacterial colonies. The system consists of a forward scatterometer for elastic light scatter (ELS) detection, a plate transporter for sample handling, and a robotic incubator for automatic incubation. To minimize the ELS pattern-capturing time, a new calibration plate and correction algorithms were both designed, which dramatically reduced correction steps during acquisition of the circularly symmetric ELS patterns. Integration of three different control software programs was implemented, and the performance of the system was demonstrated with single-species detection for library generation and with time-resolved measurement for understanding ELS colony growth correlation, using Escherichia coli and Listeria. An in-house colony-tracking module enabled researchers to easily understand the time-dependent variation of the ELS from identical colony, which enabled further analysis in other biochemical experiments. The microbial HTS system provided an average scan time of 4.9 s per colony and the capability of automatically collecting more than 4000 ELS patterns within a 7-h time span.
Show PACS
87.80.-y Biophysical techniques (research methods)
87.64.-t Spectroscopic and microscopic techniques in biophysics and medical physics

Spectral contaminant identifier for off-axis integrated cavity output spectroscopy measurements of liquid water isotopes

J. Brian Leen, Elena S. F. Berman, Lindsay Liebson, and Manish Gupta

Rev. Sci. Instrum. 83, 044305 (2012); http://dx.doi.org/10.1063/1.4704843 (5 pages) | Cited 2 times

Online Publication Date: 26 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Developments in cavity-enhanced absorption spectrometry have made it possible to measure water isotopes using faster, more cost-effective field-deployable instrumentation. Several groups have attempted to extend this technology to measure water extracted from plants and found that other extracted organics absorb light at frequencies similar to that absorbed by the water isotopomers, leading to δ2H and δ18O measurement errors (Δδ2H and Δδ18O). In this note, the off-axis integrated cavity output spectroscopy (ICOS) spectra of stable isotopes in liquid water is analyzed to determine the presence of interfering absorbers that lead to erroneous isotope measurements. The baseline offset of the spectra is used to calculate a broadband spectral metric, mBB, and the mean subtracted fit residuals in two regions of interest are used to determine a narrowband metric, mNB. These metrics are used to correct for Δδ2H and Δδ18O. The method was tested on 14 instruments and Δδ18O was found to scale linearly with contaminant concentration for both narrowband (e.g., methanol) and broadband (e.g., ethanol) absorbers, while Δδ2H scaled linearly with narrowband and as a polynomial with broadband absorbers. Additionally, the isotope errors scaled logarithmically with mNB. Using the isotope error versus mNB and mBB curves, Δδ2H and Δδ18O resulting from methanol contamination were corrected to a maximum mean absolute error of 0.93 ‰ and 0.25 ‰ respectively, while Δδ2H and Δδ18O from ethanol contamination were corrected to a maximum mean absolute error of 1.22 ‰ and 0.22 ‰. Large variation between instruments indicates that the sensitivities must be calibrated for each individual isotope analyzer. These results suggest that the properly calibrated interference metrics can be used to correct for polluted samples and extend off-axis ICOS measurements of liquid water to include plant waters, soil extracts, wastewater, and alcoholic beverages. The general technique may also be extended to other laser-based analyzers including methane and carbon dioxide isotope sensors.
Show PACS
92.40.Qk Surface water, water resources
06.20.Dk Measurement and error theory
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
back to top Gravity; Geophysics; Astronomy and Astrophysics

Damping and local control of mirror suspensions for laser interferometric gravitational wave detectors

K. A. Strain and B. N. Shapiro

Rev. Sci. Instrum. 83, 044501 (2012); http://dx.doi.org/10.1063/1.4704459 (9 pages) | Cited 3 times

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mirrors of laser interferometric gravitational wave detectors hang from multi-stage suspensions. These support the optics against gravity while isolating them from external vibration. Thermal noise must be kept small so mechanical loss must be minimized and the resulting structure has high-Q resonances rigid-body modes, typically in the frequency range between about 0.3 Hz and 20 Hz. Operation of the interferometer requires these resonances to be damped. Active damping provides the design flexibility required to achieve rapid settling with low noise. In practice there is a compromise between sensor performance, and hence cost and complexity, and sophistication of the control algorithm. We introduce a novel approach which combines the new technique of modal damping with methods developed from those applied in GEO 600. This approach is predicted to meet the goals for damping and for noise performance set by the Advanced LIGO project.
Show PACS
04.80.Nn Gravitational wave detectors and experiments
07.10.Fq Vibration isolation
07.60.Ly Interferometers
42.79.Bh Lenses, prisms and mirrors
95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close