Limit Of Measurement Range Research Articles

Optimization of a rapid method for screening drugs in blood by liquid chromatography tandem mass spectrometry.

In the recent years, liquid chromatography with tandem mass spectrometry has gained popularity in laboratories. This technique has a higher specificity, detects different analytes from a single specimen, measures analytes in distinct matrices, and substantially reduce analytical interference, with respect to immunoassay. The processing and preparation of biological samples are crucial in chromatography. Interferences in blood testing are usually caused by the presence of phospholipids and proteins. The main objective of this study was to improve analytical processes for drug screening by LC-MS/MS using a novel blood sample preparation method based on protein precipitation and removal of phospholipids. An evaluation was performed of a new method for the preparation of blood samples based on protein precipitation and removal of phospholipids by LC-Q-q-LIT. Limit of detection, limit of quantification and measurement range were determined for 56 molecules. The results of 11 cases were compared with those obtained using standard blood collection methods and instruments. The novel blood preparation and testing method based on LC-Q-q-LIT, a more sensitive technique, has demonstrated to yield comparable results to traditional methods. In addition, this new technique reduces turnaround time and costs.

Non-contact optical probe with nanometer resolution and large measurement range based on the astigmatism method

In the measurement field of micro/nano devices, many instruments have a contradiction between high resolution and large measurement range. This paper developed a non-contact optical nanometer probe based on the astigmatism method. This probe employs a high numerical aperture (NA) focusing lens to achieve nanometer resolution of the longitudinal measurement. Meanwhile, a longitudinal scanning measurement method based on two focus error signal (FES) curves is proposed to break the limit of low measurement range caused by high NA value. Therefore, it enables the probe to achieve the nanometer resolution of longitudinal measurement and large measurement ranges. The experiment results show that the longitudinal measurement resolution of the proposed probe is better than 1 nm, and the repeatability error is 17 nm. Combined with the high-precision microstage, the longitudinal range is greater than 15 μm. The proposed probe can be used for large-range longitudinal non-contact measurements with nano-scale measurement requirements.

Difference- and regression-based approaches for detection of bias

ObjectiveThis simulation study was undertaken to assess the statistical performance of six commonly used rejection criteria for bias detection. MethodsThe false rejection rate (i.e. rejection in the absence of simulated bias) and the probability of bias detection were assessed for the following: difference in measurements for individual sample pair, the mean of the paired differences, t-statistics (paired t-test), slope < 0.9 or > 1.1, intercept > 50% of the lower limit of measurement range, and coefficient of determination (R2) > 0.95. The linear regressions evaluated were ordinary least squares, weighted least squares and Passing-Bablok regressions. A bias detection rate of < 50% and false rejection rates of >10% are considered unacceptable for the purpose of this study. ResultsRejection criteria based on regression slope, intercept and paired difference (10%) for individual samples have high false rejection rates and/ or low probability of bias detection. T-statistics (α = 0.05) performed best in low range ratio (lowest-to-highest concentration in measurement range) and low imprecision scenarios. Mean difference (10%) performed better in all other range ratio and imprecision scenarios. Combining mean difference and paired-t test improves the power of bias detection but carries higher false rejection rates. ConclusionsThis study provided objective evidence on commonly used rejection criteria to guide laboratory on the experimental design and statistical assessment for bias detection during method evaluation or reagent lot verification.

Distributed control for coordinated tracking of fixed-wing unmanned aerial vehicles subject to velocity constraints

This paper considers a coordinated tracking problem of fixed-wing unmanned aerial vehicles (UAVs), whose kinematics is described as unicycle type with the constraints of both saturated angular speed and bounded linear velocity. A distributed velocity controller based on the consensus theory is designed such that UAVs can converge to the predefined formation and track the target vehicle, while the velocity constraints are satisfied. Moreover, due to the limitation of measurement range of sensors and communication bandwidth of UAV, an observer is designed when the information of neighbors’ velocity cannot be obtained. The stability of the closed-loop system is proved by using a technique lemma, which is developed based on the cascaded system. Finally, the results of numerical simulation compared with another algorithm show the effectiveness of the proposed algorithm, and a hardware-in-loop (HIL) simulation is carried out to prove the practical of the algorithm.

A point-of-need platform for rapid measurement of a host-protein score that differentiates bacterial from viral infection: Analytical evaluation

The objective was to evaluate the analytical performance of a new point-of-need platform for rapid and accurate measurement of a host-protein score that differentiates between bacterial and viral infection. The system comprises a dedicated test cartridge (MeMed BV®) and an analyzer (MeMed Key®). In each run, three host proteins (TRAIL, IP-10 and CRP) are measured quantitatively and a combinational score (0–100) computed that indicates the likelihood of Bacterial versus Viral infection (BV score). Serum samples collected from patients with acute infection representing viral (0 ≤ score < 35), equivocal (35 ≤ score ≤ 65), or bacterial (65 < score ≤ 100) scores based on pre-defined score cutoffs were employed for the analytical evaluation studies as well as samples from healthy individuals. To assess reproducibility, triplicate runs were conducted at 3 different sites, on 2 analyzers per site over 5 non-consecutive days. Lower limit of quantitation (LLoQ) and analytical measurement range were established utilizing recombinant proteins. Sample stability was evaluated using patient samples representative of BV score range (0–100).MeMed Key® and MeMed BV® passed the acceptance criteria for each study. In the reproducibility study, TRAIL, IP-10 and CRP measurements ranged with coefficient of variation from 9.7 to 12.7%, 4.6 to 6.2% and 5.0 to 11.6%, respectively. LLoQ concentrations were established as 15 pg/mL, 100 pg/mL and 1 mg/L for TRAIL, IP-10 and CRP, respectively.In summary, the analytical performance reported here, along with diagnostic accuracy established in the Apollo clinical validation study (NCT04690569), supports that MeMed BV® run on MeMed Key® can serve as a tool to assist clinicians in differentiating between bacterial and viral infection.

Pipeline leak detection and corrosion monitoring based on a novel FBG pipe-fixture sensor

Pipeline leakage and pipeline internal corrosion are two serious threats to pipeline safety operation. In this study, based on the measurement theory of pipeline internal diameter variation and a numerical simulation analysis of existing sensor shortcomings, a novel FBG pipe-fixture sensor is designed and developed to detect pipeline leakage and monitor pipeline internal corrosion simultaneously. A calibration test is conducted, and the test results indicate that the FBG pipe-fixture sensor solves the problem of a large difference between the test values and the theoretical values and eliminates the limitation of measurement range. To validate the actual performance of the sensor, a pipeline leak detection test and a pipeline internal corrosion monitoring test are, respectively, conducted on a steel pipe leak test platform and a steel pipe with different simulated corrosion levels. The test results demonstrate that the FBG pipe-fixture sensor can effectively detect pipe leakage and decrease the localization error of the leakage point to within 1 m. The sensor can also effectively monitor pipe internal corrosion and evaluate the internal corrosion degree with a measurement accuracy of 0.1 mm. The novel FBG pipe-fixture sensor may be a potential sensor for pipeline leak detection and pipeline internal corrosion monitoring.

Possibility to break through limitation of measurement range in dual-wavelength digital holography* *Project supported by the Foundation of Science and Technology Department of Shaanxi Province, China (Grant No. 2018JQ6009), the Foundation of Education Department of Shaanxi Province, China (Grant No. 17JK1165), the Beijing Natural Science Foundation, China (Grant No. Z190004), the National Natural Science Foundation of China (Grant No. 61575197),

By using the beat frequency technique, the dual-wavelength digital holography (DWDH) can greatly increase the measurement range of the system. However, the beat frequency technique has a limitation in measurement range. The measurement range is not larger than a synthetic wavelength. Here, to break through this limitation, we propose a novel DWDH method based on the constrained underdetermined equations, which consists of three parts: (i) prove that the constrained underdetermined equation has a unique integer solution, (ii) design an algorithm to search for the unique integer solution, (iii) introduce a third wavelength into the DWDH system, and design a corresponding algorithm to enhance the anti-noise performance of DWDH. As far as we know, it is the first time that we have discovered that the problem of DWDH can belong in a problem of contained underdetermined equations, and it is also the first time that we have given the mathematical proof for breaking through the limitation of the measurement range. A series of results is shown to test the theory and the corresponding algorithms. More importantly, since the principle of proposed DWDH is based on basic mathematical principles, it can be further extended to various fields, such as dual-wavelength microwave imaging and dual-wavelength coherent diffraction imaging.

A Spectrometer for Measuring the Characteristics of a Single Laser-Accelerated Electron Bunch with a Small Charge

The principles and results of the development of an electron spectrometer for a facility for the laser acceleration of electrons, which is being created at the Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, jointly with the Institute of Nuclear Physics (BINP), Siberian Branch, Russian Academy of Sciences, are described. The spectrometer uses a permanent dipole magnet and a phosphor screen and is designed for an energy range of 15–150 MeV. The main requirements that determine the features of this spectrometer are as follows: the location of the basic elements in a vacuum chamber of limited volume and operation in the mode of single pulses at small charges in a pulse, at a level of 1–10 pC. Methods for selecting the measurement scheme and geometry and the requirements for the elements that constitute the spectrometer and their selection are described. It is demonstrated that the beam collimation at the spectrometer entrance allows achievement of an energy resolution of up to 5% at the high-energy limit of the measurement range. The results of testing a spectrometer prototype on the VEPP-5 beam at the BINP, at which the sensitivity of registering the charge density at a level of 0.01 pC/mm2 was experimentally achieved, are presented.

Three-Dimensional Measurement Method of Four-View Stereo Vision Based on Gaussian Process Regression

Multisensor systems can overcome the limitation of measurement range of single-sensor systems, but often require complex calibration and data fusion. In this study, a three-dimensional (3D) measurement method of four-view stereo vision based on Gaussian process (GP) regression is proposed. Two sets of point cloud data of the measured object are obtained by gray-code phase-shifting technique. On the basis of the characteristics of the measured object, specific composite kernel functions are designed to obtain the initial GP model. In view of the difference of noise in each group of point cloud data, the weight idea is introduced to optimize the GP model, which is the data fusion based on Bayesian inference method for point cloud data. The proposed method does not require strict hardware constraints. Simulations for the curve and the high-order surface and experiments of complex 3D objects have been designed to compare the reconstructing accuracy of the proposed method and the traditional methods. The results show that the proposed method is superior to the traditional methods in measurement accuracy and reconstruction effect.

An Acoustic Resonance-Based Liquid Level Detector With Error Compensation

In the liquid level measurement principle based on acoustic resonance, level height is usually calculated via the detected fundamental resonance frequency (RF), which limits that the upper limit of measurement range is only about 8.28 m when air is a gas medium. In order to increase the measurement range, a new liquid level detector is presented using a group of RFs generated in a given frequency range instead of the single fundamental RF. The measuring accuracy of the detector can be improved by the use of error compensator based on belief rule base. This compensator enables the detector to learn compensation values from reference detection cycles; therefore, such a system is flexible and can be easily optimized under specific operating conditions. The experimental gauge is built by using low-cost components including a speaker, a microphone, a thermometer, a waveguide, a controller, and tested within a wide range with the upper limit reaching to more than 10 m. It has a better overall performance than that of the original detector.

Industrial SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm

Abstract. SO2 variability over a large concentration range and interferences from other gases have been major limitations in industrial SO2 emission monitoring. This study demonstrates accurate industrial SO2 emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm. The proposed analyzer features a large dynamic measurement range and correction of interferences from other coexisting infrared absorbers such as NO, CO, CO2, NO2, CH4, HC, N2O, and H2O. The multichannel gas analyzer measures 11 different wavelength channels simultaneously to correct several major problems of an infrared gas analyzer including system drift, conflict of sensitivity, interferences among different infrared absorbers, and limitation of measurement range. The optimized algorithm uses a third polynomial instead of a constant factor to quantify gas-to-gas interference. Measurement results show good performance in the linear and nonlinear ranges, thereby solving the problem that the conventional interference correction is restricted by the linearity of the intended and interfering channels. The results imply that the measurement range of the developed multichannel analyzer can be extended to the nonlinear absorption region. The measurement range and accuracy are evaluated through experimental laboratory calibration. Excellent agreement was achieved, with a Pearson correlation coefficient (r2) of 0.99977 with a measurement range from approximately 5 to 10 000 ppmv and a measurement error of less than 2 %. The instrument was also deployed for field measurement. Emissions from three different factories were measured. The emissions of these factories have been characterized by different coexisting infrared absorbers, covering a wide range of concentration levels. We compared our measurements with commercial SO2 analyzers. Overall, good agreement was achieved.

Quality assurance in immunoassay performance-temperature effects

Temperature is one factor that influences the performance of immunoassays. Most commonly all incubation steps of the immunoassay are performed at ambient temperature. To systematically study the influence of temperature deviations on assay parameters like signal variation coefficients, limit of detection and measurement range, direct competitive enzyme immunoassays for the determination of two anthropogenic markers, caffeine and carbamazepine, were run at different temperatures above and below room temperature during individual assay steps. The temperature during the competition step had the greatest impact on the assay sensitivity yielding changes in test midpoints by a factor of 10 to 15. For carbamazepine, the test midpoints varied from 36 ng L−1, 108 ng L−1 to 378 ng L−1 employing 4 °C, 21 °C, or 37 °C as incubation temperature, respectively. The edge effect can be minimized resulting in a good plate homogeneity with small variation coefficients, when the assay is performed at ambient temperature.