计量科学与技术

Study on Diffraction Efficiency of LiF220 Crystal Based on Single-Energy X-Rays

WANG Zhen, GUO Siming, HUANG Shikui, LI Zhiwei, ZHOU Xing, SHU Ziyao, FAN Lipeng, WANG Zhongtao

, Available online , doi: 10.12338/j.issn.2096-9015.2023.0322

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Based on K fluorescence X-rays, the diffraction efficiency experiments of LiF220 crystals at 23.3 keV and 31 keV energies were carried out, and the Bragg angle of the incident single-energy X-rays was adjusted to measure the diffraction single-energy X-rays, and the experimental results showed that the crystals could obtain relatively complete diffraction peaks under the two energies. Under the irradiation of 23.3 keV and 31 keV, the maximum diffraction efficiency is about 2.46% and 1.33%, which is consistent with the theoretical value, when the incident angle is 10.8° and 8.1°, respectively. This study provides experimental data support and reference for research in materials science and other related fields. Measurements of diffraction efficiency can be used to verify the accuracy of experimental results. It provides a tool to test experimental conditions and data interpretation, ensuring reproducibility and reliability of the study.

Application of Infrared Thermography on the Measurement of the Focal Plane of a Focused Transducer

ZHAO Wei, CAO Huiyuan, WU Yanqi, TAO Jie, YU Yaping

, Available online , doi: 10.12338/j.issn.2096-9015.2023.0280

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In order to better study the acoustic field characteristics of focused ultrasound transducers, this paper proposes a method for measuring the focal domain size of focused transducers using infrared thermal imaging technology. The focal size is determined by placing a thin film type sound-absorbing material on the focal plane of the transducer and measuring the temperature distribution on the focal plane under ultrasound power using an infrared thermal imager. This article simultaneously used the hydrophone scanning method to measure the same focusing transducer, and conducted a theoretical analysis of the sound field distribution of the focusing transducer. The results showed that the inconsistency of the -6dB beam width was within 5%, verifying the feasibility of using infrared thermal imaging technology to measure the sound field distribution of the focusing ultrasonic transducer.

Research Progress of Graphene Quantum Dots and Graphene Quantum Dots Reference Materials

LIU Ran, LV Qingbin, ZHAO Haibo, LIANG Liang, SHEN Shangyi, ZHAO Xiaoning

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0217

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Graphene quantum dots refer to a new type of fluorescent carbon material with a transverse size of less than 30 nm and a layer number of less than 10 layers. Due to their unique characteristics and broad application prospects, graphene quantum dots have received extensive attention. In this paper, the unique structure, electrical and optical properties of graphene quantum dots are introduced, the main preparation methods of graphene quantum dots are summarized, and their applications in new energy, catalysis, sensing, biomedicine and environmental remediation are introduced in detail. Finally, the research progress of graphene quantum dots standard materials is briefly introduced. Future research on graphene quantum dots is mainly focused on improving the photoluminescent quantum yield and manufacturing output, as well as expanding the application range and preparing graphene quantum dot standard materials. With the progress of new material design concepts and the continuous development of quantum technology, graphene quantum dots and their standard materials are expected to show their unique advantages and application value in more fields.

Research on Characterization Method of Cardiac Troponin I by Hydrogen-Deuterium Exchange Mass Spectrometry

SUN Haofeng, MA Lingyun, LIU Jianyi, ZHANG Qi, SONG Dewei

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0166

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Acute myocardial infarction (AMI) ranks first among the death factors in China, and is the top priority in the clinical prevention and treatment of cardiovascular diseases. Myocardial troponin I (cTnI), as the most reliable clinical index of evaluating myocardial injury, is currently the preferred biomarker and gold standard for the diagnosis of myocardial infarction. Immunology method is a common method of clinical detection AMI, many domestic and foreign diagnostic reagent suppliers can produce cTnI detection kit, but immune testing system from different manufacturers will produce different value results for the same sample, on the one hand, the commercial kits of different suppliers in sensitivity, specificity and selectivity, on the other hand is different kits used in different antibodies, identify antigen epitope region, antibody and serum cTnI sample binding ability differences, resulting in inconsistent results between different manufacturers, thus affect the accuracy of clinical diagnosis. The consistency and accuracy of the quantitative results are closely related to the structure of cTnI. However, due to the complexity of cTnI, the structural characterization of cTnI in the solution state is very challenging. Through experimental condition optimization and data processing parameters, the characterization method of cTnI HDX, based on hydrogen deuterium exchange-mass spectrometry (HDX-MS) technology, is established, and applied to the study of cTnI. Meanwhile, this method has good universality and can be easily extended to cTnI conformation transition study and the development of kinetic method, which lays the technical foundation for promoting the standardization of cTnI from the perspective of protein structure.

Research on Multi-Parameter Calibration Method of Spoofing Satellite Navigation Interference Simulation Source

HU Hao, LIU Hanyao, LIU Wei, SU Ze

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0114

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With the rapid development of satellite navigation technology, satellite navigation interference simulation source is widely used in UAV countermeasures, anti-interference equipment test evaluation and so on. In this paper, based on the basic functions and main parameters of spoofing satellite navigation interference simulation source and referring to relevant standards and specifications, the parameter calibration method of spoofing satellite navigation interference simulation source is deeply studied, and the calibration method for RF signal, transmit power, spectrum purity, error vector amplitude, interference characteristics and 1PPS timing error is proposed. The simulation sources of different types of spoofing satellite navigation interference are tested and analyzed. The results show that the calibration method of each parameter has strong operability, which can effectively measure and trace the spoofy-type satellite navigation interference simulation source scientifically and rationally, and promote the application development of satellite navigation interference simulation source.

Development and Experimental Study of Automatic Verification Device of Alpha and Beta Surface Contamination Monitor

LIU Meiling, YANG Zhijie, SUN Changhao, MAO Chuanlin, LI Hongnan, LIU Haoran, LIANG Juncheng

, Available online , doi: 10.12338/j.issn.2096-9015.2023.0361

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In order to improve the efficiency and accuracy of the verification, reduce the influence of manual operation, reading and recording during the verification of α and β surface contamination monitor, an automatic verification device was developed based on automatic technology and machine vision algorithm. The automatic system consists of a double-layer turntable, an image training software based on machine vision technology, and an process control software based on C#. The verification process, hardware structure and software were designed and optimized. To raise the accuracy of optical character recognition(OCR) recognition, the function of abnormal data identification was designed by filtering the conditions based on the characteristics of the target area. For the purpose of verifying the performance of the device, identification rate test, background influence test, comparative test and automatic verification test were carried out. The consequences show that the recognition rate of the device reaches 100%, and the additional background interference due to the concentrated placement of planar sources within the device was not detected. In addition, the relative deviation of measurement results using manual positioning bracket and automatic verification device is within −6.0%, two results are consistent within the range of uncertainty. On the basis of meeting the requirements of JJG 478-2016, this device optimizes the radiation protection and the inherent safety of the sources, and further improves the verification efficiency.

Analysis of the Structural-related Impurities Involved in 3,3',5-Triiodo-L-thyronine (T3) Purity Reference Material

XIAO Peng, SONG Dan, LI Hongmei

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0134

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Research and development of 3,3',5-Triiodo-L-thyronine (T3) purity reference material is a way to establish the primary material for clinical measurement value traceability, which can provide more accurate and comparable evidence in thyroid disease diagnosis. In the mass balance quantitative approach, determining and analyzing those structural-related impurities is essential. Such investigation could also be an effective way to reduce the uncertainty of the standard value. First, nuclear magnetic resonance and high-resolution mass spectrometry analytical tools have been employed to validate the chemical structure of the reference material. Then, the structural-related impurities are separated and qualitatively analyzed by using reliable analytical technologies, including high-performance liquid chromatography, high-resolution mass spectrometry, and ion mobility spectrometry. The results indicated that there are three kinds of structural-related impurities involved in the T3 purity reference material (NIM-RM3239), which are Diiodo-L-thyronine, Chloro-diiodo-L-thyronine, and L-Thyroxine. The relative content of each impurity is greater than 0.1% in UV 220nm. Furthermore, the chiral isomer separation result indicated that no dextroisomer (D-T3) existed in NIM-RM3239. These analytical results can be utilized as the foundations in the mass balance approach, applied in developing T3 primary certified reference material.

Present Status of Monoenergetic Neutron Production Technology and Reference Radiation Fields

LI Fan, ZHANG Hui, WANG Pingquan, ZHANG Yanan

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0059

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Neutron is an important tool for studying nuclear structure, nuclear reaction laws, particle physics, astrophysics, and the structure of matter. It is widely used in fields such as nuclear energy, national defence, material science, life sciences, medical health, radiation protection, and semiconductors. Among these, monoenergetic neutron field plays an increasingly important role in nuclear energy applications and ionizing radiation metrology. Therefore, national metrology institutes have established monoenergetic neutron reference radiation fields. The National Institute of Metrology, China will build this facility within the next 3 to 5 years to improve China’s neutron metrology system, carry out fundamental research on neutron physics, and meet the corresponding needs for monoenergetic neutron from various sectors. Based on the latest version of ISO 8529-1:2021, this article analyses and calculates the parameters of the five most commonly used nuclear reactions in the field of monoenergetic neutrons in terms of neutron energy, neutron yield, neutron angular distribution, and accompanying γ-ray background. It also summarizes the present status and characteristics of existing monoenergetic neutron reference radiation fields and introduces the main equipment commonly used in these fields, provides important parameters for the new monoenergetic neutron reference radiation field to be built by the National Institute of Metrology, China.

Study of Manganese Content of Pure Manganese Flake Reference Material for X-Ray Energy/Wave Spectrometer Calibration

TIAN Donghui, SHEN Yanfei, WANG Zhigang, CHEN Yaling, HU Gang, ZHOU Zhou, PU Cheng, LIU Ping, LIU Wenjun, SHI Yunxiao, LI Xu

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0053

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In this work a reference material of manganese content of pure manganese flake for X-ray energy/wave spectrometer calibration was developed. The homogeneity and stability of manganese content in the pure manganese flake were tested using electronic probe. The manganese content (mass fraction, %) of the reference material was determined using an inductively coupled plasma emission spectrometer (ICP-OES) and an inductively coupled plasma mass spectrometry (ICP-MS). The uncertainties of the reference material were evaluated. The results show that the pure manganese flake has good homogeneity and stability. The standard value of manganese content of the reference material is 99.48% and the expanded uncertainty is 0.92 % (k=2). The reference material of pure manganese flake for EDS/WDS calibration can meet the calibration needs during the quantitative analysis process of EDS/WDS and provide technical support for the analysis of manganese element in scientific research and industry in China.

Research on Seismometer Calibration and its Consistency of Transfer Function

KONG Chuijie, ZUO Aibin, ZHOU Jinfeng

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0055

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The sensitivity calibration of seismometers was carried out using the national standard of the ultra-low frequency vibration with a typical seismometer 3T-120PH as an example. The results of the vibration calibration data are compared and analyzed with the transfer function results of the seismometers. When the frequency is lower (below 10Hz), the vibration calibration results agree very well with the transfer function results, and when the frequency is higher (above 10Hz) the two begin to diverge. Since the vibration calibration method realistically transmits vibration signals to the seismometers, which is in line with the actual use situation, the seismometers using the shaker calibration method is more responsive to the realism of the seismometers at work than the results of the electrical calibration method.

Current Status of Serum Theophylline Standardization in Clinical Laboratories

DU Yuanyuan, ZHANG Qiaoxuan, HAN Liqiao

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0115

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Theophylline is a widely used medication for treating asthma and chronic obstructive pulmonary disease (COPD). It’s essential to accurately monitor the blood concentration of theophylline, due to the significant inter-individual variability and its narrow therapeutic window. Currently, immunoassays, high-performance liquid chromatography (HPLC), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are commonly used as routine methods for measuring serum theophylline in clinical laboratories. However, there is significant difference among the measurement results of these methods. The reference measurement procedure for serum theophylline in the Joint Committee for Traceability in Laboratory Medicine (JCTLM) database is the isotope dilution gas chromatography-mass spectrometry (ID-GC/MS) method. The primary reference material was developed by the UK Laboratory of the Government Chemist (LGC) and China National Institute of Metrology (NIM). No secondary reference material with serum matrix was reported. To ensure the reliability and harmonization of measurement results, it is important to establish a comprehensive traceability chain for the standardization of serum theophylline.

Biomarkers for Alzheimer’s disease: Quantitation Techniques and the Standardization

ZHOU Xirui, GU Renji, MA Ruimin, JIANG Wencan, LUO Shizhong, FENG Liuxing

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0054

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Alzheimer’s disease (AD) is an irreversible neurodegenerative disease highly prevalent in the elderly population aged 65 and above. With the population aging in our country, AD has become a major issue affecting global public health and social development. The pathogenesis of AD is still unclear, and there are currently no effective drugs to reverse or prevent the progression of the disease. A combination of highly specific diagnostic biomarkers is crucial for early and accurate diagnosis for disease, and it is also a prerequisite for an effective disease therapy. Reliable clinical diagnosis of AD calls for the development of highly sensitive, accurate, and high-throughput quantitative techniques for AD biomarkers. Promoting the standardization of clinical testing related for AD biomarkers can significantly improve the consistency, commutability, and traceability of clinical results obtained from different platforms. This review summarizes the evolution of diagnostic criteria for AD, states the current status of AD-relevant drug development, it also lists important diagnostic biomarkers for AD and introduces corresponding quantitation techniques. Finally, the standardization progress made in quantitation techniques for AD-related diagnostic biomarkers are prospected. We hope this review could provide useful guidance for the development of standard reference materials and also reference measurement procedures in related fields, it is also anticipated that this review could help to improve the performance IVD products and platforms in relative areas.

Quantitative Analysis of Recombinant Human Serum Amyloid A by Isotope Dilution Mass Spectrometry

ZHANG Qi, JIANG Zelin, SONG Dewei

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0163

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Serum amyloid A (SAA) is one of the four inflammation biomarkers in clinical diagnosis. At present, there is no SAA certified reference materials, which cannot achieve traceability and standardization in clinical SAA diagnosis. In this study, the recombinant human serum amyloid A expressed in E. coli was selected as the raw material, and it was qualitatively and quantitatively analysed to study the traceability method. The purity and molecular weight of SAA were analysed by gel electrophoresis, liquid chromatography and mass spectrometry. The results showed that the purity of SAA was >98%, and the molecular weight of 11820.09 Da was consistent with the theoretical value. An absolute quantification method of amino acid analysis-isotope dilution mass spectrometry for SAA was established. The content of phenylalanine, isoleucine and proline in the hydrolysed sample was determined at 8 h of hydrolysis, and the mass concentration of SAA solution was 9.32 µg/g (RSD = 0.91%). An absolute quantification method of signature peptide-isotope dilution mass spectrometry for SAA was established. Within the mass ratio of trypsin and SAA was 1:1 and digestion time was 8 h, the content of peptide EANYIGSDK, GPGGVWAAEAISDAR was detected by IDMS, and the mass concentration of SAA is calculated to 9.41 g/g (RSD = 0.49%). The results of the two methods were consistent by statistical test, and there was no significant difference shown. The quantitative results of this study are traceable to SI units, which lays a foundation for the development of SAA reference materials.

A Review of Electric Field Measurement and Microwave Sensing Based on The Rydberg Atomic Aperture

ZHAO Danhua, CHEN Jiarui, BAO Luwei, ZHU Jiahui

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0148

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In recent years, the application of Rydberg atoms in the field of microwave measurement has gradually emerged and become a research hotspot in quantum metrology. Compared with the traditional microwave sensing technology, the Rydberg atomic system shows higher sensitivity, stronger anti-interference ability and unique quantum traceability. These advantages give Rydberg atoms great potential in microwave measurements. Despite the advantages of the Rydberg atomic system, its complex energy level structure and diverse interactions with electromagnetic waves pose challenges with engineering applications. At present, the application of "atomic aperture" based on Rydberg atoms in the field of traditional microwave sensing is still in its initial stage, and there is a huge room for improvement. In order to demonstrate the advantages of the Rydberg atoms in microwave measurement, and solve its limitations in practical application, we discuss the application prospect of the Rydberg atomic system on the basis of the previous research results. With the continuous progress of technology, the Rydberg atoms are expected to achieve accurate measurement in a wider range of frequency bands, providing strong support for wireless communication, radar detection and other fields.

Application of CNN-LSTM Model Integrating Prophet and PCA Technology in Water Quality Prediction

XIAO Ke, ZHANG Jianjun, TAN Wenwu, WANG Li, SONG Lingyu, LIN Haijun

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0109

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In order to reduce the error rate that may occur when traditional CNN-LSTM models are used for water quality prediction, a CNN-LSTM water quality prediction method based on Prophet model and PCA is proposed. During the cleaning process of water quality monitoring data, Prophet model is used for outlier handling, PCA method is used to reduce the dimensionality of influencing variables, eliminate variable correlation, and use the processing results as input for the CNN-LSTM model to predict the total nitrogen index of water quality. The experimental results show that this method has significantly improved compared to the CNN-LSTM model in terms of MAE, RMSE, and MSE evaluation indicators. Among them, MSE increased by 13%, RMSE increased by 6.7%, and MAE increased by 5.6%.

Data Processing Methods for Reflectivity Level in Microwave Anechoic Chamber

ZHAO Xing, BAN Hao, HONG Li, LIU Xiao

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0087

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The microwave anechoic chamber is an enclosed space specifically designed for measurements in the microwave frequency range. It is used as an experimental site for measurements in areas such as antenna and target scattering characteristics, to simulate free space. Compared to outdoor test sites, the microwave anechoic chamber has the advantages of being able to operate all day, and having low reflection. In practical applications, due to the fact that the absorbing materials laid inside cannot completely absorb electromagnetic waves in specific frequency bands, there will still be interfering reflected signals in the test area of the anechoic chamber, these reflected signals enter the test area from various directions and overlap with the direct waves between the transceiver antennas, thus forming a spatial standing wave distribution over a certain distance in the test area. The interference reflection index in the test area is characterized by reflectivity level of the quiet zone . When the microwave anechoic chambers are used to measure parameters such as antenna radiation patterns, the reflectivity level of the quiet zone at different angles in the microwave anechoic chamber should be evaluated. The measurement method of microwave anechoic chamber reflectivity level of the quiet zone often adopts the free-space voltage standing wave ratio (VSWR) method. In the test area, the vector sum of the direct signal and reflected signal forms a spatial standing wave on a certain path. The data processing method of the spatial standing wave determines the calculation result of the reflection level in the quiet zone, and the selection method of the peak-to-peak value of the standing wave in the actual test curve directly determines the measurement result. This article discusses in detail the collection and processing methods of reflection level data in microwave anechoic chambers, which can help optimize on-site measurement and testing schemes, and has positive significance for the optimal design of quiet zone scanning frames.

Research of a Monopole Antenna Calibrator Based on Equivalent Capacitance Method

LIU Guanjun, CHEN Yisheng, CHANG Zhifang

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0101

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The equivalent capacitance method is the main calibration method for monopole antennas given in CISPR 16-1-6. The principle is to use an equivalent capacitor to simulate an actual monopole element for the calibration of the corresponding antenna factor, and the electric capacity of this equivalent capacitor is equal to the capacity of the monopole antenna itself. Based on the working principle of the equivalent capacitance method, a miniaturized and highly versatile antenna calibrator is designed. Simulation and experimental results show that the calibrator can be well applied to the calibration work of the monopole antenna. The evaluation process and results of the measurement uncertainty of the method are given, and the results show that the extended uncertainty of the measurement results is about 1.7 dB (k=2) when the antenna factor of the monopole antenna is calibrated by this device.

Laser Multilateration Coordinate Measurement Systems and Development Status:A Review

ZHANG Qingyan, LI Jianshuang, MIAO Dongjing

, Available online , doi: 10.12338/j.issn.2096-9015.2024.0100

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The laser multilateral coordinate measuring system has the characteristics of high coordinate measurement accuracy, which has attracted much attention from academic circles, industries and metrology institutions in various countries. However, since the accuracy of coordinate measurement in large spatial ranges is affected by various factors, and there is a lack of domestic standards related to the measurement and calibration of laser multilateral coordinate measurement systems, the development of laser multilateral coordinate measurement systems still faces many problems that need to be solved. This article focuses on the principle of laser multilateral measurement, system parameter self-calibration method, coordinate measurement traceability status and the formulation of related standards, measurement uncertainty assessment and analysis of influencing factors, the extension of laser multilateral coordinate measurement in the field of attitude measurement, and the application in the industrial field at home and abroad Extensive research and summary have been conducted on its practical applications. Among them, domestic and foreign researchers have made a variety of attempts to improve measurement accuracy, such as compensating environmental field interference, reducing ranging errors, improving system self-calibration accuracy, increasing the number of measurement stations, setting constraints, and researching the optimal layout of the system. At the same time, the establishment and improvement of relevant standards for domestic laser polygonal coordinate measurement system measurement, calibration and traceability can provide reference and basis for the manufacturing and assembly of large parts and components in industrial applications and the calibration and compensation of instruments. This article reviews the relevant literature on laser multilateral coordinate measurement systems in the field of large spatial range measurement, focusing on the principles of laser multilateral coordinate measurement, system parameter self-calibration methods, coordinate measurement uncertainty and applications, aiming to provide researchers with information on The development status and future development trends of laser multilateral coordinate measurement systems promote the development of coordinate measurement technology in large spatial ranges.

Uncertainty Evaluation of Determination of the Gross Alpha Radioactivity and Gross Beta Radioactivity in Drinking Water

GU Xinyi, GU Jun, CHENG Xiaohong

, Available online , doi: 10.12338/j.issn.2096-9015.2023.0277

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To evaluate the uncertainty of determination of the gross alpha radioactivity and the gross beta radioactivity in drinking water by thick source method. According to GB/T 5750.13-2023 "Standard Examination Methods for Drinking Water Part 13 Radioactivity Index", the gross alpha radioactivity and beta radioactivity in drinking water are measured. The measurement repeatability was regarded as type A uncertainty, and the factors introduced by the residue mass, water sample volume, instrument detection efficiency, recovery rate, etc. were regarded as type B uncertainty. The measured gross alpha and beta radioactivity concentrations were 0.66 Bq/L and 0.48 Bq/L, the relative combined uncertainties were 6.0% and 5.7%, and the expanded uncertainties were 0.08 Bq/L and 0.06 Bq/L. Uncertainty introduced by the instrument count rate (n) is the main source of uncertainty and has the greatest influence. The measurement repeatability, the counting efficiency (ε) of standard powder source and radioactivity recovery rate (F) have greater influence. The influences of total mass of the water sample residue (W), mass of the water residue weighed to prepare the sample source (m) , and the volume (V) of the water sample are less and negligible.

The Development of Small Pulling Force Gauge Calibration Device

ZHANG Duoli, JIN Longxue, WU Yueming

, Available online , doi: 10.12338/j.issn.2096-9015.2021.0037

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Point at present situation of measuring small pulling forcegauge inmetrological service,small pulling forcegauge calibration device was developed,so some matterswhensmallpulling forcegauge is measured usingWeight,for example ,heavy working intensity,unablezeroed and full scale range cannot be measured ,can be solved.

Measurement Comparison of Plasmid DNA Capability by Digital PCR

WANG Xia, NIU Chunyan, LIU Zheng, LU Lin, DONG Lianhua

, Available online , doi: 10.12338/j.issn.2096-9015.2021.0590

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Digital PCR (dPCR) is an absolute quantitative technique of nucleic acid, which is widely used in transgenic and gene detection. In order to ensure the accuracy and reliability of digital PCR measurement results in China, 16 laboratories were tested using transgenic plasmid DNA samples. The comparison results showed that the difference between the ratio of foreign gene to internal copy number (<25%) to evaluate the measuring ability of the laboratories. The 16 laboratories were all within the acceptable range, and there was no significant difference among different digital PCR platforms. Due to the influence of plasmid conformation, the absolute copy number content of plasmid DNA measured in 7 laboratories was significantly lower than the reference value. It is suggested that when using digital PCR for quantitative measurement of plasmid DNA copy number, it should be confirmed whether the conformation of plasmid has an effect on amplification.

, Available online , doi: 10.12338/j.issn.2096-9015.2020.0166

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In mmwave technology a low frequency is always multiplied to generate a much higher frequency. Phase noise will be also increased and phase noise test will be more important in mmwave band. It is limited with spectrum analyzer method because of some reasons. And phase noise analyzer can only cover up to 50 GHz in a single unit. After the basic introduction of phase noise test technology in mmwave band two external mixer method is provided. Result shows that with this method we can get a stable test result.

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