计量科学与技术

2023, 67(3): 1-2.

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Amino Acid Mass Spectrometry Based on Polarity-Reversing Nano-Electrospray Ionization

LI Kangming, GAO Xiaomei, GONG Xiaoyun, GONG Aijun

2023, 67(3): 3-11, 71. doi: 10.12338/j.issn.2096-9015.2023.0062

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Amino acid analysis has always been a crucial aspect of chemical and biological research due to its essential biological significance and diverse roles in living organisms, including catalyzing chemical reactions, signaling, and supporting cell structure. Mass spectrometry possesses significant advantages in terms of sensitivity and accuracy among various amino acid analysis methods. Liquid chromatography-mass spectrometry (LC-MS) is the most commonly used method for amino acid mass spectrometry analysis, requiring an electrospray ion source. While the electrospray ion source has many advantages, such as high sensitivity, high selectivity, simple operation, compatibility with various types of mass spectrometers, and a wide range of analyzable substances, its ionization efficiency for amino acids is limited, particularly for acidic amino acids. This limitation hinders further improvement of the detection sensitivity of analytical methods. A mass spectrometry method for determining 20 common amino acids was established based on a self-developed Polarity-Reversing Nano-Electrospray Ionization (PR-nESI) ion source. PR-nESI enhances detection by altering the high-voltage strategy during the nano-spray process. Compared to conventional Nano-Electrospray Ionization (nano-ESI) methods, PR-nESI significantly improves the detection signal-to-noise ratio, increasing up to tens of times. Moreover, PR-nESI exhibits strong desalting effects, effectively inhibiting the formation of metal ion adducts of amino acids, which significantly facilitates spectral identification, particularly for biomolecules in salt buffer systems. The amino acid detection method presented in this study holds promising future application prospects in clinical and food fields.

Research on Calibration and Compensation Methods for Single-Axis Linear Errors of Inclinometer Probes

WANG Li, QIU Zhengyu, YANG Lu, LIU Lijuan

2023, 67(3): 12-19. doi: 10.12338/j.issn.2096-9015.2022.0232

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This research focuses on the calibration and compensation methods for single-axis linear errors in inclinometer probes. The study begins with an analysis of the probe's technical parameters, working principles, characteristics, and installation methods during use and calibration, aiming to investigate the sources of measurement errors when applied in the construction and engineering monitoring fields. From these error sources, specific solutions are identified, employing the least squares method for compensation of the probe's single-axis linear error. A new calibration method for the inclinometer probe, based on an optical dividing head, is proposed. The study conducts experimental comparisons of measurement results before and after the compensation of single-axis linear error. The results indicate that the proposed method can significantly reduce the single-axis linear measurement error of the inclinometer probe. Measurement uncertainty is evaluated and analyzed to validate that the calibration method meets the requisite standards. Lastly, the effectiveness of the compensation method is verified through repeated installation trials.

Research Progress in Electric Field Intensity Calibration Techniques

XING Hao, HE Zibin, WU Mengjuan, WANG Biyun, WANG Kai, CHEN Quan, LU Congjun, ZHANG Huiru, LIU Yumei

2023, 67(3): 20-28, 42. doi: 10.12338/j.issn.2096-9015.2023.0035

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This paper presents the current development trends of electric field intensity calibration technologies domestically and internationally. The research status of TEM cells, GTEM cells, coaxial cone TEM cells, monocone TEM cells, microwave anechoic chambers, and electromagnetic reverberation chambers in universities, research institutes, and metrology institutions worldwide is emphasized. The design structure and performance parameters of various devices are introduced. A comparison is made between the characteristics, applications, and suitable environments of the various electric field intensity calibration equipment mentioned in this paper. Lastly, based on the research progress of electric field intensity calibration technology, the development trend of on-site electric field intensity calibration to meet the rapid calibration requirements of field strength sensors under production line field conditions is proposed.

An Investigation into Methods of Beam Quality Analysis for Medical Linear Accelerators Based on Pylinac

GAO Xiang

2023, 67(3): 29-34. doi: 10.12338/j.issn.2096-9015.2023.0003

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The accuracy and stability of the beam quality in medical linear accelerators (LINAC) are crucial for the precision of radiation therapy. This study introduces a more convenient and accurate method for quantitatively analyzing beam characteristics using the open-source Pylinac program. Beam quality information was obtained using thimble ionization chambers and electronic portal imaging devices (EPIDs). The Python-based Pylinac program was used for quantitative analysis of the absolute output dose, flatness, symmetry, and percentage depth dose curves. Furthermore, the results of the EPID analysis were compared with those of mainstream detection analysis instruments, such as MapCheck. The program was able to accurately calculate the absolute output dose and other parameters, with no significant differences observed between the results of the EPID and MapCheck (p < 0.05). The gamma (1 mm/1%) value indicated a high level of consistency between the measured curves and the model data (γ = 96.2%). Pylinac can accurately evaluate the beam quality characteristics of accelerators and can serve as a tool for daily, monthly, and annual inspections.

Design of a Dual-Channel Josephson Array Test System

MA Mengze, CAO Wenhui, LI Jinjin, XU Da, WANG Shijian, GAO He, ZHONG Qing, ZHONG Yuan

2023, 67(3): 35-42. doi: 10.12338/j.issn.2096-9015.2023.0023

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In response to the growing demand for chip testing, a dual-channel Josephson array test system was designed, incorporating key components such as low-temperature test probes and microwave transmission structures. The test system enables simultaneous measurement of two programmable Josephson devices and provides superimposed voltage output of the two chips. The system's functionalities were validated by measuring a dual-channel programmable Josephson device. The optimal operating frequency of the device is 17 GHz, with an operating power of 11 dBm without a power amplifier. For the dual-channel small voltage programmable Josephson device, the minimum array consists of 1 junction with an output voltage of 35.15 μV, and the maximum array contains 512 junctions with an output voltage of 17998.42 μV. The broadening range of quantum voltage steps is 2 μV. This is due to 34420A (1 V range) noise and testing system noise, which meets the requirements of quantum voltage testing.The dual-channel quantum voltage output is 70.30 μV for a single junction and 35996.84 μV for 512 junctions, the broadening range of quantum voltage steps after superposition is also within 2 μV. This demonstrates that the dual-channel Josephson array test system can not only measure two independent programmable chips but also achieve quantum voltage superimposed output without increasing process difficulty.

Development and Analysis of Vacuum Adiabatic Oxygen Bomb Calorimeter

HU Biao, LAN Sai, TAN Zhongzhu, LIU Chen, HU Yuhang

2023, 67(3): 43-49. doi: 10.12338/j.issn.2096-9015.2023.0086

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In order to better meet the needs of trade settlement, clean utilization, and carbon emission accounting for energy materials, and to improve the measurement accuracy and precision of the calorific value of combustible materials, a high-precision adiabatic oxygen bomb calorimeter based on vacuum Dewar bottle technology was developed. This paper introduces the basic structure and working principle of the calorimeter, and proposes a suitable testing procedure and method. The calorimeter's heat capacity and the calorific value of combustion materials were tested using benzoic acid (SRM39j) from the National Institute of Standards and Technology (NIST) as an example. The error uncertainty of calorific value indication was evaluated, and the linearity of the temperature circuit, the effective range of calorific value, and the environmental adaptability of the calorimeter were discussed. Test data show that the relative standard deviation of heat capacity is 0.047%, the change over three months is 0.138%, the calorific value indication error for benzoic acid is 17.8 J·g⁻¹, and the expanded uncertainty of measurement is 27.8 J (k=2). The linearity of the temperature circuit is 0.99993, the effective testing range is 15800-37000 J, and the environmental adaptability of the calorimeter needs to be improved.

Development of Magnetizing Current Calibration Device for On-Line

LIU Hanyao, HU Hao, LIU Wei, HUANG He

2023, 67(3): 50-55. doi: 10.12338/j.issn.2096-9015.2023.0069

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Magnetic particle flaw detectors are essential nondestructive testing equipment, widely used in the manufacturing industry, typically comprising two current circuits for circumferential and longitudinal magnetization. The accuracy of the magnetizing current is a critical measurement indicator during calibration, serving as a principal parameter ensuring the quality of magnetic particle detection. The standard accuracy grade is generally level 5 or 10. This study addresses the issues encountered during the calibration of the magnetizing current of such detectors and the need for on-site calibration. Considering the current status of high-current measurement technologies both domestically and internationally, we propose an on-line calibration device for magnetic particle flaw detectors based on shunt and Hall sensor sampling. Optimizing the shunt design and employing suitable Hall sensors allows for the calibration of AC/DC circumferential and longitudinal magnetizing currents. Integrated design enables the measurement of magnetizing current operation time, and analysis of basic error, frequency, waveform, and other parameters. We conducted AC/DC circumferential and longitudinal magnetizing current calibration tests on the prototype device, which demonstrated an accuracy level of 0.5, meeting calibration specification requirements. Its simple structure and convenient calibration facilitate on-site online calibration, thereby providing more technical support for enhancing nondestructive testing quality in magnetic particle flaw detectors.

Effects of Solar Radiation on the Flow Field Correction Coefficient of the Ultrasonic Flowmeter for Natural Gas

FAN Yuguang, WANG Yin, GAO Lin, JI Xue

2023, 67(3): 56-64, 34. doi: 10.12338/j.issn.2096-9015.2023.0067

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In 2021, China’s consumption of natural gas exceeded 300 billion cubic meters. Even slight measurement discrepancies in such volumes can result in significant economic impacts, and yet, the reliability of currently utilized natural gas flowmeters in the market leaves much to be desired. The ultrasonic flowmeter for natural gas, a non-contact flow measurement device, is widely used but its measurement accuracy is affected by numerous factors. Using the ANSYS simulation platform and considering the geographical location and seasonal characteristics of Xi'an, a numerical model of a DN300 pipeline's four-path ultrasonic flowmeter was established to study the coupling effects of solar radiation factors within the natural gas transmission environment. The time-difference method of the ultrasonic flowmeter for natural gas measures pipeline fluid flow by utilizing the difference in ultrasonic wave transit time. The flow correction coefficient, a key parameter in the metering of the ultrasonic flowmeter, is defined as the ratio of the path-line average speed to the cross-sectional average speed of the pipeline. Simulation results reveal that with changes in solar radiation energy, the relative error of the flow field correction coefficient experiences only slight changes. When the solar radiation coupled air velocity is considered, the relative error range of the flow field correction coefficient with solar radiation in winter is between 0.005% and 0.091%, and in summer it's between 0.048% and 0.27%. The magnitude of change in summer is noticeably greater than in winter. To improve the measurement accuracy of the ultrasonic flowmeter, a secondary correction of the ultrasonic flowmeter device can be carried out at noon during the hotter summer days.

Research Progress of Neonicotinoid Pesticides Certified Reference

TU Mengling, YANG Bingxin, ZHU Yunxiao, LI Xianjiang

2023, 67(3): 65-71. doi: 10.12338/j.issn.2096-9015.2023.0111

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Neonicotinoid pesticides, characterized by high efficiency, broad-spectrum application, low toxicity, and remarkable selectivity, are now the most widely used insecticides worldwide. Nonetheless, these pesticides pose potential risks to the human nervous and reproductive systems through exposure via drinking water, food, and inhalation. This paper comprehensively summarizes the types, sample preparation techniques, and value assignment methodologies for certified reference materials (CRMs) of neonicotinoid pesticides, crucial for ensuring accurate, comparable, and traceable quantitative detection results. In China, CRMs primarily consist of purity and solution reference materials, chiefly incorporating acetamiprid and imidacloprid. However, there is a significant shortage of matrix reference materials. Purity CRMs are typically prepared by purifying commercially available materials, and their values are primarily assigned using mass balance methods and differential scanning calorimetry. Conversely, international institutes have developed a plethora of matrix CRMs for neonicotinoid pesticides, containing various analytes. These matrix samples are prepared by spiking blank or positive samples with the expected concentration of analytes and are subsequently quantified using liquid chromatography isotope dilution mass spectrometry (LC-ID-MS). The development of neonicotinoid pesticide CRMs in China lacks balance both in type and structure. Hence, the development of multi-component and multi-level matrix CRMs for neonicotinoid pesticides needs to be accelerated to improve the quantitative traceability system and meet the growing demand for extensive testing.

Study on Reference Materials of Copper Content in Aluminum-Copper Thin Films

ZHANG Ran, CUI Lei, WANG Yalei, ZHANG Yi, TAO Xingfu, LI Xu

2023, 67(3): 72-79. doi: 10.12338/j.issn.2096-9015.2023.0096

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An aluminum-copper (Al-Cu) thin film reference material for copper content, intended for the calibration of X-ray energy/wave spectrometers, was developed in this study. The uniformity and stability of the developed Al-Cu thin film reference material were evaluated using an electronic probe. An inductively coupled plasma emission spectrometer (ICP-OES) was employed to determine the copper content (wt%) of the reference material. The sources of uncertainty for the copper content in the Al-Cu film standard with a nominal value of 49.5% were examined, and the uncertainty of the reference material was evaluated. The findings indicate that the reference material displays good uniformity and stability. The copper content standard value of the reference material was found to be 49.46 wt%, with an extended uncertainty of 0.98 wt% (k=2). The developed Al-Cu thin film copper content reference material for X-ray energy/wave spectrometer calibration meets the calibration requirements for quantitative analyses conducted with X-ray energy/wave spectrometers. It fills a domestic gap in reference materials for X-ray energy/wave spectrometer calibration and provides a measurement assurance and technical support for the quantitative analysis of copper content in China's scientific research industry.

2023 Vol. 67, No. 3

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