Reduce Measurement Time Research Articles

Improving a gas ion source for 14C AMS

For more than 4 years, gaseous samples of 1–50μg carbon have been routinely measured with the gas ion source of the small AMS (Accelerator Mass Spectrometer) facility MICADAS (MIni CArbon DAting System) at ETH Zurich. The applied measurement technique offers a simple and fast way of 14C measurements without the need of sample graphitization. A major drawback of gaseous 14C measurements, however, is the relatively low negative ion current, which results in longer measurement times and lower precision compared to graphitized samples. In December 2009, a new, improved Cs sputter ion source was installed at MICADAS and we began to optimize conditions for the measurement of gaseous samples. 12C− currents from the new ion source were improved from initially 3 to 12–15μA for routine measurements and the negative ion yield was increased by a factor of 2, reaching 8% on average during routine operation. Moreover, the new measurement settings enable a doubled CO2 flow, thus substantially reducing measurement times. The achieved performance allows closing the sample size gap between gaseous and solid samples and makes the gas ion source a promising tool for dating with a measurement precision of 5‰ on samples as small as 50μg carbon.

Time-Optimized 15N qNMR Determination of Lewis and Brønsted Site Concentrations and Chemical Bonding of Pyridine at Brønsted Sites in Amorphous Aluminum Hydroxide Fluoride

Time-optimized 15N quantitative NMR (qNMR) is described for the precise determination of Lewis and Bronsted site concentrations per gram catalyst, enabling a measurement time reduction of more than...

Birefringent prism based Fourier transform spectrometer

This paper presents the design of a rugged and compact Fourier transform spectrometer (FTS) utilizing a birefringent prism, a pair of polarizers and a linear CCD array. This design improves on existing FTS by eliminating moving parts and spreading the optical path difference (OPD) spatially (rather than temporal scanning), making the system smaller, more reliable, and dramatically reducing measurement times. Both the theoretical models for the design and experimental results of the prototype are presented. The optical performance is tested using LEDs of known wavelengths, with the fringe counting technique employed during interferogram acquisition to ensure accurate sampling of the interferogram at constant OPD intervals. Reconstructing the spectra showed that the detected wavelengths deviated from the actual wavelengths by less than 1 nm.

Measurement strategies and uncertainty estimations for pitch and step height calibrations by metrological atomic force microscope

Gratings and step height standards are useful transfer standards for lateral and vertical length scale calibration of atomic force microscopes (AFMs). In order to have traceability to the SI-meter, the standards must have been calibrated prior to use. Metrological AFMs (MAFMs) with online laser interferometric position measurements are versatile instruments for the calibrations. The developed task-specific measurement strategies for step height and pitch calibrations with the Centre for Metrology and Accreditation's (MIKES's) metrological AFM are described. The strategies were developed to give high accuracy and to reduce measurement time. Detailed uncertainty estimations for step height and grating pitch calibrations are also given. Standard uncertainties are 0.016 and 0.018 nm for 300 and 700 nm pitch standards, respectively, and 0.21 and 0.44 nm for 7 and 1000 nm step height standards.

Non-destructive evaluation of stone-impact damages using Pulsed Phase Thermography

Stone chipping caused specific damages of coating systems, such as delamination, paint loss, or fracture of interlayer, were studied by Pulsed Phase Thermography. The measurement is based on the influence of individual barriers, which are created by defects, on the thermal heat flux. Defective and intact layer systems can be well distinguished, due to the clearly diverse return signals. We moreover demonstrate how the signals can be correlated with specific defects. The main advantages compared with currently used methods are the reliable and improved localization and identification of defects, as well as the significant reduction of measurement time.

Effect of Scan Time on Perfusion and Flow Extraction Product (K-Trans) Measurements in Lung Cancer Using Low-Dose Volume Perfusion CT (VPCT)

To assess the effect of measurement time on blood flow (BF), blood volume (BV), and k-trans-values (flow extraction product) in patients undergoing volume perfusion computed tomography (VPCT) for lung cancer. This prospective study was approved by our local Research Ethics Committee and informed consent was obtained in all patients. Between December 2009 and December 2010, 75 VPCT scans were obtained in 54 consecutive patients (15 women, 39 men) with histologically confirmed lung cancer. A 64-second VPCT of the tumor (80 kV, 60 mAs) using 128 × 0.6-mm collimation, 6.9-cm z-axis coverage and a total of 26 volume measurements, was performed. BF, BV, and K(trans) were determined. Data evaluation was performed for different measurement times (64 seconds, 45 seconds, 39 seconds, and 36 seconds) by removing the last two, four, and five scans and repeating the analysis. A one-way repeated-measures analysis of variance was used to test for effects of measurement time on BF, BV, and k-trans and unpaired/paired Student t-tests were applied for comparisons within/between groups, respectively. No effect of measurement time on BF values was noted (P > .05), whereas a significant decrease of BV values (at 39 seconds: 71% ± 2% of 64-second values) and a significant increase of k-trans-values (at 39 seconds: 146% ± 8% of 64-second values) were observed with progressively shortened measurement time (P < .05, respectively). Additionally, with reduced measurement time, the increase in k-trans-values was significantly more pronounced in those patient groups with higher BV (at 39 seconds: 171% ± 15% versus 120% ± 3% of 64-second measurements), and those with lower k-trans (at 39 seconds: 167% ± 16% versus 126% ± 4% of 64-second measurements) (P < .05, respectively). Whereas estimation of BF in lung cancer was independent from VPCT measurement time within the chosen ranges, approximation of both BV and k-trans was affected by measurement duration. A fixed measurement time of 40 seconds is recommended.

QUANTIFYING RIVER ACCRETION IN THE UPPER RIO GRANDE GORGE, NEW MEXICO, BY USING AN ACOUSTIC DOPPLER CURRENT PROFILER

ABSTRACTThe section of the upper Rio Grande in New Mexico is important to downstream water management and the administration of water rights. It has long been believed that this remote reach of the Rio Grande is characterized by significant groundwater accretions, which contribute to water available for downstream uses. This study focused on the uppermost 30 miles of the Rio Grande in New Mexico seeking to establish locations of groundwater accretions in the reach and document magnitude of gain. In order to quantify the accretion of the upper Rio Grande, an expedition using inflatable kayaks, an acoustic Doppler current profiler (ADCP) and an electromagnetic meter was carried out in the fall of 2008 when natural surface flow was low. The study area covered a stretch of 31 miles. The expedition was able to determine that the total accretion of this stretch of the Rio Grande was 22 ft3s−1 with an average accretion rate of 0.73 ft3s−1 mile−1. Most of the reach exhibited minimal gain or loss, and most of the accretion was centred in Sunshine Valley. One of the most significant results was encountering a large artesian, subaqueous spring, which might be the largest documented spring in New Mexico and contributes nearly 50% of the accretion in the reach. The study was also able to characterize the exact locations of other significant groundwater inputs. In addition to quantifying the accretion of part of the upper Rio Grande, the study provides the framework for using advanced technology in the form of an ADCP to determine river accretions in remote locations. ADCPs offer the benefit of reducing measurement time and measurement error, collect high‐resolution data and are non‐intrusive. Overall, the use of ADCP technology to determine river accretion offers an improvement over traditional methods, and it is the hope of the authors that this technology is utilized for river accretion studies in the future. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Fast terahertz reflection tomography using block-based compressed sensing

In this paper, a new fast terahertz reflection tomography is proposed using block-based compressed sensing. Since measuring the time-domain signal on two-dimensional grid requires excessive time, reducing measurement time is highly demanding in terahertz tomography. The proposed technique directly reduces the number of sampling points in the spatial domain without modulation or transformation of the signal. Compressed sensing in spatial domain suggests a block-based reconstruction, which substantially reduces computational time without degrading the image quality. An overlap-average method is proposed to remove the block artifact in the block-based compressed sensing. Fast terahertz reflection tomography using the block-based compressed sensing is demonstrated with an integrated circuit and parched anchovy as examples.

High-speed three-dimensional shape measurements of objects with laser speckles and acousto-optical deflection

Many three-dimensional (3D) shape measurement techniques in stereophotogrammetry with temporal coded structured illumination are limited to static scenes because the time for measurement is too long in comparison to the object speed. The measurement of moving objects result in erroneous reconstructions. This is apparent to reduce measurement time to overcome this limitation, which is often done by increasing the projection rate for illumination while shrinking the amount of images taken for reconstruction. The projection rate limits most applications in its speed because digital light processing (DLP) projectors, which are widely used, bring a limited projection rate along. Our approach, in contrast, does not take a DLP. Instead we use laser speckles as projected patterns which are switched using an acousto-optical deflector. The projection rate is 10× higher than what the fastest stripe projection systems to our knowledge achieve. Hence, we present this uncommon but potential approach for highspeed (≈250 3Dfps= [3D measurements per second]), dense, and accurate 3D measurements of spatially separated objects and show the media that emphasizes the ability of accurate measurements while the objects under testing move.

Two methods for transmission line simulation model creation based on time domain measurements

Abstract. The emission from transmission lines plays an important role in the electromagnetic compatibility of automotive electronic systems. In a frequency range below 200 MHz radiation from cables is often the dominant emission factor. In higher frequency ranges radiation from PCBs and their housing becomes more relevant. Main sources for this emission are the conducting traces. The established field measurement methods according CISPR 25 for evaluation of emissions suffer from the need to use large anechoic chambers. Furthermore measurement data can not be used for simulation model creation in order to compute the overall fields radiated from a car. In this paper a method to determine the far-fields and a simulation model of radiating transmission lines, esp. cable bundles and conducting traces on planar structures, is proposed. The method measures the electromagnetic near-field above the test object. Measurements are done in time domain in order to get phase information and to reduce measurement time. On the basis of near-field data equivalent source identification can be done. Considering correlations between sources along each conductive structure in model creation process, the model accuracy increases and computational costs can be reduced.

DEVELOPMENT OF PRACTICAL MEASUREMENT EQUIPMENT OF MEMBRANE STRESS FOR MEMBRANE STRUCTURES

One of the most important matters in keeping membrane structures in healthy condition is to maintain the proper tension distribution over the membrane. However, it is not easy to know the real stress level in the membrane quantitatively after completion of the structures. The authors proposed a new method that can measure membrane stresses in two different directions separately using sound waves –instead of measuring the membrane stresses directly. In this paper, various problems in the downsizing of measurement equipment and reduction of measurement time for practical application are examined, and clarified both theoretically and experimentally. In addition, not only the experimental tests using the membrane material of PTFE coated glass fabric as well as ETFE film with various combinations of the membrane stress, but also the actual measurement for existing suspension structure covered with ETFE film is carried out for practical use. The results verify the developed equipment can be used to continue measurement as a tool for scientifically and quantitatively determining the membrane stress which exists in the membrane material of the actual membrane structures.

Deep and Highly Sensitive Proteome Coverage by LC-MS/MS Without Prefractionation

In-depth MS-based proteomics has necessitated fractionation of either proteins or peptides or both, often requiring considerable analysis time. Here we employ long liquid chromatography runs with high resolution coupled to an instrument with fast sequencing speed to investigate how much of the proteome is directly accessible to liquid chromatography-tandem MS characterization without any prefractionation steps. Triplicate single-run analyses identified 2990 yeast proteins, 68% of the total measured in a comprehensive yeast proteome. Among them, we covered the enzymes of the glycolysis and gluconeogenesis pathway targeted in a recent multiple reaction monitoring study. In a mammalian cell line, we identified 5376 proteins in a triplicate run, including representatives of 173 out of 200 KEGG metabolic and signaling pathways. Remarkably, the majority of proteins could be detected in the samples at sub-femtomole amounts and many in the low attomole range, in agreement with absolute abundance estimation done in previous works (Picotti et al. Cell, 138, 795–806, 2009). Our results imply an unexpectedly large dynamic range of the MS signal and sensitivity for liquid chromatography-tandem MS alone. With further development, single-run analysis has the potential to radically simplify many proteomic studies while maintaining a systems-wide view of the proteome.

Fast and High‐Resolution Stereochemical Analysis by Nonuniform Sampling and Covariance Processing of Anisotropic Natural Abundance 2D 2H NMR Datasets

Natural abundance deuterium (NAD) 2D NMR spectroscopy using chiral or achiral liquid crystals is an efficient analytical tool for the stereochemical analysis of enantio- or diastereomers by the virtue of proton-to-deuterium substitution. In particular, it allows the measurement of enantiopurity of organic synthetic molecules or the determination of the natural isotopic (1)H/(2)H fractionation in biological molecules, such as fatty acid methyl esters (FAME). So far, the NAD 2D spectra of solutes were acquired by using uniform sampling (US) and processed by conventional 2D Fourier transform (FT), which could result in long measurement times for medium-sized analytes or low solute concentrations. Herein, we demonstrate that this conventional approach can be advantageously replaced by nonuniform sampling (NUS) processed by covariance (Cov) transform. This original spectral reconstruction provides a significant enhancement of spectral resolution, as well as a reduction of measurement times. The application of Cov to NUS data has required the introduction of a regularization procedure in the time domain for the indirect dimension. The analytical potential of combining Cov and NUS is demonstrated by measuring the enantiomeric excess of a scalemic mixture of 2-ethyloxirane and by determining the diastereomeric excess of methyl vernoleate, a natural FAME. These two organic compounds were aligned in a polypeptide (poly(γ-benzyl-L-glutamate)) mesophase. In the case of NAD 2D NMR spectroscopy, we show that Cov and NUS methods allow a decrease in measurement time by a factor of two compared with Cov applied to US data and a factor of four compared with FT applied to US data.

Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm∕200 nm and ±0.04 arcsec∕0.1 arcsec at 1000 Hz.

High-Throughput Characterization Method for Crystallization Temperature of Integrated Thin Film Amorphous Alloys Using Thermography

We introduce the high-throughput characterization of the crystallization temperature Tx of thin film amorphous alloys integrated into a thin film library. This characterization is achieved using thermography. A new thin film library is designed and fabricated using photolithography and a lift-off process. Using a homogeneous composition thin film library, the validity of the proposed method is confirmed. The crystallization of all samples can be detected simultaneously, and the measured Tx distribution is about 8 K. Three compositionally distributed thin film libraries of the Pd–Cu–Si alloy system were then fabricated using combinatorial arc plasma deposition (CAPD), and the Tx values of the samples on the three libraries were measured. In the three libraries, Tx for 285 amorphous samples could be measured, and there was an obvious distribution in Tx depending on the sample composition. At two selected compositions, the measured Tx values agree with differential scanning calorimetry (DSC) results within 8 K. In terms of throughput, the proposed method achieves a measurement time reduction of 66% compared with a conventional method using DSC. Consequently, the proposed method enables the high-throughput combinatorial characterization of the Tx of thin film amorphous alloys.

Device for Rapid and Agile Measurement of Diffusivity in Micro- and Nanochannels

The lack of a viable theory for describing diffusivity when fluids are confined at the micro- and nanoscale [Ladero et al. Chem. Eng. Sci.2007, 62, 666-678; Deen AIChE J.1987, 33, 1409-1425] has necessitated accurate measurement of diffusivity (D) [Jin and Chen Chromatographia2000, 52, 17-21; Nie et al. Science1994, 266, 1018-1021; Durand et al. Anal. Chem.2009, 81, 5407-5412], crucial for a host of micro- and nanofluidic technologies [Grattoni et al. Curr. Pharm. Biotechnol.2010, 11, 343-365]. We demonstrate a rapid and agile method for the direct measurement of diffusivity in a system possessing 10(4) to 10(5) precisely fabricated channels with characteristic sizes (β) ranging from micro- to nanometers. Custom chambers allowed us to measure the diffusivity in a closed unperturbed system using UV/vis spectroscopy. D was measured for rhodamine B (RhoB) in aqueous solution in channels of 200 and 1 μm, as well as 13 and 5.7 nm. The observed logarithmic scaling of diffusivity with β, in close agreement with prior experiments, but far from theoretical prediction, surprisingly highlights that diffusivity is significantly altered even at the microscale. Accurate measurement of D by reducing the size of the source reservoir by 3 orders of magnitude (from 150 μL to 910 nL) proves that a substantial reduction in measurement time (from 7 days to 40 min) can be achieved. Our design thus is ready for rapid translation into a standard analytical tool--useful for multiple applications.

Mixture quantification using PLS in plastic scintillation measurements

This article reports the capability of plastic scintillation (PS) combined with multivariate calibration (Partial least squares; PLS) to detect and quantify alpha and beta emitters in mixtures. While several attempts have been made with this purpose in mind using liquid scintillation (LS), no attempt was done using PS that has the great advantage of not producing mixed waste after the measurements are performed. Following this objective, ternary mixtures of alpha and beta emitters ((241)Am, (137)Cs and (90)Sr/(90)Y) have been quantified. Procedure optimisation has evaluated the use of the net spectra or the sample spectra, the inclusion of different spectra obtained at different values of the Pulse Shape Analysis parameter and the application of the PLS1 or PLS2 algorithms. The conclusions show that the use of PS+PLS2 applied to the sample spectra, without the use of any pulse shape discrimination, allows quantification of the activities with relative errors less than 10% in most of the cases. This procedure not only allows quantification of mixtures but also reduces measurement time (no blanks are required) and the application of this procedure does not require detectors that include the pulse shape analysis parameter.

A computer-aided plant for studying the kinematic viscosity of high-temperature metallic melts

A system for studying damping of torsional vibrations of a crucible with a melt is described. Reasons for errors and their values are analyzed. The patented technical solutions decreasing errors of measuring the kinematic viscosity to 3% are designed and implemented. The system is intended to reduce measurement times and simplify operation of the plant’s operator.

Advanced Neutron Reflectometer for Investigation on Dynamic/Static Structures of Soft-Interfaces in J-PARC

A novel neutron reflectometer with horizontal geometry will be established at BL16 in Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC) as a successor of a reflectometer ARISA-II. ARISA-II corresponding to a single neutron beam downward at 2.22 deg has achieved off-specular and time-resolved reflectivity measurements. The novel reflectometer is designed so as to receive two tilted neutron beams (2.22 & 5.71 deg), which gives us an opportunity in investigation on a free liquid surface. The reflectometer can provide a micro-sized beam by slit collimation and obtain a fair reflectivity with small sample area. Also, T0 chopper and neutron focusing mirror are newly introduced. The T0 chopper can suppress the background due to fast neutrons. The focusing mirror produces further reduction of measurement time not only for specular reflection by focusing neutrons on a sample, but also grazing incidence small-angle neutron scattering (GISANS) measurements by focusing on a detector.

Effectiveness of Using the "Rise-to-Peak time" Index as a Guide for Ultrasound Evaluation of Articular Cartilage

Background. “Rise-to-Peak time” has been proposed as an index of the probe angle during ultrasound measurement. The aim of this study is to quantitatively evaluate the effectiveness of this index as a guide for ultrasound evaluation of articular cartilage. Methods. “Acceptance”, defined as the normalized difference between the index value at a target position and the index value at a deviated position, was calculated using the “Rise-to-Peak time” for materials with varying surface roughness. Findings. Echoes from rough surfaces had lower amplitude values compared with those from flat surfaces. Meanwhile, “Rise-to-Peak time” was little-affected by the surface roughness of the reflection surface. Also, echo amplitude had a large negative “Acceptance” compared with Rise-to-Peak time. Interpretation. These results suggest that the “Rise-to-Peak time” index is effective in reducing measurement time and measurement error during articular-cartilage evaluation.