System Of Units Research Articles

LIME: Lunar Irradiance Model of ESA, a new tool for absolute radiometric calibration using the Moon

Abstract. Absolute calibration of Earth observation (EO) sensors is key to ensuring long-term stability and interoperability, and it is essential for long-term global climate records and forecasts. The Moon provides a photometrically stable calibration source within the range of the Earth's radiometric levels and is free from atmospheric interference. However, to use this ideal calibration source, one must model the variation in its disc-integrated irradiance resulting from changes in Sun–Earth–Moon geometries. The Lunar Irradiance Model of the European Space Agency (LIME) is a new lunar irradiance model developed from ground-based observations acquired using a lunar radiometer operating from the Izaña Atmospheric Observatory near Mount Teide, located in Tenerife, Spain. Nightly top-of-atmosphere (TOA) irradiance is determined using the Langley plot method, and each observation is traceable to the international system of units (SI) through the radiometer calibration performed at the National Physical Laboratory (NPL). Approximately 590 lunar observations acquired between March 2018 and December 2022 currently contribute to the model parameter derivation, which builds on the widely used ROLO (Robotic Lunar Observatory) model analytical formulation. This paper presents the strategy used to derive LIME parameters: the characterisation of the lunar radiometer, the derivation of nightly top-of-atmosphere lunar irradiance and a description of the model parameter derivation, along with the associated metrologically rigorous uncertainty. The model output has been compared to PROBA-V, Pléiades and Sentinel-3B, as well as to the VITO implementation of the ROLO model. Initial results indicate that LIME predicts 3 %–5 % higher lunar-disc-integrated irradiance than the ROLO model for the visible and near-infrared channels. The model output has an expanded (k=2) radiometric uncertainty of ∼ 2 % at the lunar radiometer wavelengths, and it is expected that planned observations until at least 2024 further constrain the model parameters in subsequent updates.

Near- to mid-IR spectral purity transfer with a tunable frequency comb: Methanol frequency metrology over a 1.4 GHz span

We report the upgrade and operation of a frequency-comb-assisted high-resolution mid-infrared molecular spectrometer, allowing us to combine high spectral purity, International System of Units (SI)-traceability, wide tunability, and high sensitivity. An optical frequency comb is used to transfer the spectral purity of a SI-traceable 1.54 μm metrology-grade frequency reference to a 10.3 μm quantum cascade laser (QCL). The near-infrared reference is operated at the French time/frequency metrology institute, calibrated there to primary frequency standards, and transferred to Laboratoire de Physique des Lasers via the REFIMEVE fiber network. The QCL exhibits a linewidth of δν ∼ 0.1 Hz and a sub-10−15 relative frequency stability from 0.1 to 10 s, and its frequency is traceable to the SI with a total relative uncertainty better than 4 × 10−14 after 1 s averaging time. We have developed the instrumentation allowing comb modes to be continuously tuned over 9 GHz, resulting in a QCL of record spectral purity uninterruptedly tunable at the precision of the reference over an unprecedented span of Δν = 1.4 GHz. We have used our apparatus to conduct sub-Doppler spectroscopy of methanol in a multi-pass cell, demonstrating state-of-the-art frequency uncertainties down to the few kilohertz level (∼10−10 in relative value). We have observed weak intensity resonances unreported so far, resolved subtle doublets never seen before, and brought to light discrepancies with HITRAN. This demonstrates the potential of our apparatus for probing subtle internal molecular processes, building accurate spectroscopic models of polyatomic molecules of atmospheric or astrophysical interest, and carrying out precise spectroscopic tests of fundamental physics.

On non-SI units accepted for use with the SI in a digital system of units

Abstract. There is a need to develop an unambiguous digital version of the International System of Units (SI), as required for information systems and distributed sensor networks. This leads to a reconsideration of the status of the non-SI units accepted for use with the SI. Here, the case of the non-SI units dalton (Da), neper (Np), bel (B) and decibel (dB) is considered.

An LC-MS/MS-based platform for the quantification of multiple amyloid beta peptides in surrogate cerebrospinal fluid

IntroductionThe accurate quantification of amyloid beta (Aβ) peptides in cerebrospinal fluid (CSF) is crucial for Alzheimer's disease (AD) research, particularly in terms of preclinical and biomarker studies. Traditional methods, such as the enzyme-linked immunosorbent assay (ELISA), have limitations. These include high costs, labor intensity, lengthy processes, and the possibility of cross-reactivity. ObjectivesThe primary objectives of this research were twofold: to comprehensively characterize Aβ peptides and to develop a reliable and accurate method for the simultaneous quantification of Aβ 1–40 and Aβ 1–42 peptides in surrogate CSF that is traceable to the International System of Units (SI). MethodsWe developed a novel method that combined solid phase extraction (SPE) with isotope dilution liquid chromatography/tandem mass spectrometry (ID-LC/MSMS). SPE was employed to efficiently eliminate matrix interferences, while [15N] Aβ1-40 and [15N] Aβ1-42 served as internal standards to improve accuracy. In addition, we introduced Peptide Impurity Corrected Amino Acid Analysis (PICAA) to ensure traceability to the SI and reliable quantification of Aβ peptides. ResultsThe developed platform demonstrated a linear calibration range of 300–20000 pg/ml for both Aβ1-42 and Aβ1-40 peptides, accompanied by strong correlation coefficients greater than 0.995. Quality Control (QC) samples demonstrated an accuracy of at least 90.0 %. ConclusionThe enhanced specificity and flexibility of the developed platform potentially have implications for Alzheimer's disease diagnosis and future investigations of novel Aβ peptide biomarkers.

A candidate reference measurement procedure for the quantification of α-synuclein in cerebrospinal fluid using an SI traceable primary calibrator and multiple reaction monitoring.

α-synuclein aggregation is an important hallmark of neurodegenerative diseases such as Parkinson's disease (PD) and Lewy body dementia. α-synuclein has been increasingly used as a diagnostic biomarker in PD and other synucleinopathies. Current clinical assays rely on antibody-based immunoassays to detect α-synuclein, which possess high sensitivity, afford high throughput and require small sample volumes. The utility of these assays, however, may be compounded by the specificity, selectivity and batch-to-batch heterogeneity of the antibody used, which can lead to deviations in the total amount of the protein measured when comparing results among different laboratories. Similarly, current mass spectrometry-based quantification methods for α-synuclein lack well-defined, value assigned calibrators to ensure comparability of measurements. Therefore, there is still an unmet need for the standardisation of clinical measurements for α-synuclein that can be achieved by the development of reference measurement procedures (RMPs) utilising calibrators traceable to the SI (International System of Units). Here, we report a candidate RMP for α-synuclein, using an SI traceable primary calibrator and an isotope dilution mass spectrometry (IDMS) approach to address this need. The gravimetrically prepared primary calibrator was traceably quantified utilising a combination of amino acid analysis (AAA) and quantitative nuclear magnetic resonance (qNMR) for value assignment. An optimised targeted sample clean-up procedure involving a non-denaturing Lys-C digestion and solid-phase extraction strategy was devised, followed by the development of a targeted multiple reaction monitoring (MRM) method for the quantification of α-synuclein in cerebrospinal fluid (CSF). This candidate RMP was then deployed for the sensitive detection and accurate quantification of multiple proteotypic α-synuclein peptides in patient derived CSF samples. The LC-MS based results were subsequently compared to immunoassay data to assess the overall performance of our approach. The development and adoption of this candidate RMP, along with the availability of the SI traceable primary calibrator will allow for reliable quantifications of α-synuclein in CSF by an LC-MS based assay. The RMP will potentially contribute towards the standardisation of this important biomarker and may lead to future interlaboratory comparisons.

On-Site Calibration Procedure and Uncertainty Contributions on Air Temperature Sensors

Due to the increasing demand of climate change studies, traceability of measurements according to the International System of Units (SI) becomes fundamental to establish data quality and comparability in time. With the aim of guaranteeing the traceability, in October 2022, an on-site calibration of three thermometers operated by the Osservatorio meteorologico di Moncalieri was assessed. The calibration by comparison against traceable travelling standards was performed in a transportable thermal chamber manufactured by the Istituto Nazionale di Ricerca Metrologica (INRIM). Results showed that the main uncertainty contributions to the expanded uncertainty were the interpolation method, the chamber inhomogeneity and the repeatability of the sensors under calibration. This current calibration was compared with previous calibration in 2012 (on-site calibration) and in 2016 (laboratory calibration). The comparison analysis evidenced the drift effect on the thermometers and the importance of having an active calibration program to reduce this effect. Regarding the expanded uncertainty, both on-site calibrations presented the same order of magnitude and smaller than the correction values. This paper points out the advantage of performing an on-site calibration: since the calibration involves the same dataloggers and cables in the same environmental conditions, the calculated calibration curve represents more convincingly the real measurement conditions.

Intercomparison of Landsat OLI and JPSS VIIRS Using a Combination of RadCalNet Sites as a Common Reference

Independent radiometric data collected from multiple ground sites as part of vicarious calibration activities can be combined to harmonize the data products of Earth observation sensors with different temporal, spectral, and spatial resolutions. Recent coordinated international efforts for open fiducial reference measurements have provided the worldwide user community with new ways to explore the calibration and harmonization of data produced by the sensors. To be correct, the results from each ground system must be traceable to the same well-understood standard system, and ideally to the international system of units (SI). Additionally, the calibration test site should be homogeneous over an area larger than the spatial resolutions of each sensor, so that ground measurements are representative of the area seen by the sensors being calibrated. Here, we use a combination of independent and SI-traceable radiometric data provided from two sites of the Radiometric Calibration Network (RadCalNet) to compare the radiometric response of sensors with different spectral and spatial resolutions that operate on different orbits. These sensors are Operational Land Imagers (OLI) of the Landsat-8 and Landsat-9 missions, and Visible Infrared Imaging Radiometer Suites (VIIRS) of the Suomi-National Polar-Orbiting Operational Environmental Satellite System Preparatory Project (SNPP) and Joint Polar Satellite System-1 (JPSS-1) missions. The sensor radiometric responses are compared via temporal averaging of the ratios of top-of-atmosphere reflectance values for each sensor to those reported by RadCalNet. Our intercomparison results show that these on-orbit sensors are calibrated within their absolute radiometric uncertainties. The absolute radiometric uncertainties of single-sensor over single-site intercomparisons at 550 nm is between 5% and 6%. Having the opportunity to look at the intercomparison results of Landsat-9 OLI compared to each calibration site individually and then in combination allowed us to investigate potential systematic site-dependent biases. We did not observe significant site-dependent biases in the behavior of the four on-orbit sensors compared to the calibration sites. The absolute radiometric uncertainty of a single sensor over multiple-site intercomparisons at 550 nm is 5.4%. We further investigated site-dependent biases by looking at the double-ratio calibration coefficients of the on-orbit sensors, calculated with reference to those sites.

Analytical Methods Based on the Mass Balance Approach for Purity Evaluation of Tetracycline Hydrochloride.

Analytical methods based on the mass balance approach were developed for the purity evaluation of tetracycline hydrochloride, a representative salt compound used in pure veterinary drug analysis. The purity assignment method was used to quantify individual classes of impurities via independent analytical techniques. The mass fraction of the free base or salt form contained in a high-purity organic compound with a hydrochloride salt can be determined. The chloride content by ion chromatography-conductivity detector (IC-CD) and general classes of impurities, including structurally related impurities by liquid chromatography-ultraviolet (LC-UV) detector, water by Karl Fischer (KF) coulometric titration, residual solvents by headspace sampler gas chromatography/mass spectrometry (HS-GC/MS), and non-volatiles by thermogravimetric analyzer (TGA), were considered to calculate the purity of the mass fraction. The chloride content of the salt compound can be considered the main impurity in the mass fraction of the free base in the salt compound. A purity assay using quantitative nuclear magnetic resonance (q-NMR) as a direct determination method was performed to confirm the results of the mass balance method. The assigned purities of the tetracycline free form and its salt form in mass fraction were (898.80 ± 1.60) mg/g and (972.65 ± 1.58) mg/g, respectively, which are traceable to the international system of units (SI). Thus, the procedure for evaluating the purity of the free base and salt forms in the salt compound is newly demonstrated in this study.

Energy and exergy analysis of an integrated system with solar methane cracking and co-electrolysis of CO2/H2O for efficient carbon management

In this paper, an integrated system is proposed for the production of turquoise hydrogen from methane cracking using solar energy. The produced hydrogen and carbon by-products are used in fuel cells to generate clean electricity. Syngas is produced through power generated via photovoltaics, using a solid oxide electrolyzer cell (SOEC). The SOEC co-electrolyzes the exhaust CO2 from the direct carbon fuel cell, along with H2O. The resulting syngas is subsequently converted into methanol. The system is modelled using Aspen Plus to obtain the thermodynamic evaluation. Mass, energy, entropy, and exergy balances are performed over the system's units. The energy and exergy efficiency of the subsystems is determined, with solar methane cracking system achieving energy and exergy efficiencies of 82.2% and 92.5%, respectively. The overall system produces methanol and generates 7.71 MW of electricity with the overall energy and exergy efficiencies of 40.6% and 37.5%, respectively.

Using an Absolute Cavity Pyrgeometer to Calibrate Pyrgeometers Outdoors with Respect to the International System of Units

Accurate measurement of the atmospheric longwave irradiance is important for renewable energy and atmospheric science applications. Pyrgeometers are deployed outdoors all over the world to measure the atmospheric longwave irradiance and presently are calibrated with traceability to the interim standards for atmospheric longwave radiation measurement, the standards are based on four pyrgeometers and their average irradiance is the World InfraRed Standard Group (WISG) which is developed and maintained by The Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (PMOD/WRC). Since 2013 the InfraRed Integrating Sphere (IRIS) developed by PMOD/WRC and the Absolute Cavity Pyrgeometer (ACP) developed by the National Renewable Energy Laboratory (NREL) have been compared outdoors six times at different locations and the difference between the measured atmospheric longwave irradiance by ACP and IRIS was less than 2 W/m<sup>2</sup> with traceability to the International System of Units (SI). During the six comparisons the irradiance measured by the interim WISG was 5 W/m<sup>2</sup> lower than the irradiance measured by the average irradiance measured by the ACP and IRIS [1]. Based on this discrepancy, the World Meteorological Organization’s Commission for Instruments and Methods of Observation (CIMO) recommended that the interim WISG should be adjusted to be traceable to SI units [2]. In anticipation of CIMO’s expert team agreement on establishing the world reference using the average irradiance measured by ACP and IRIS in this article we describe a procedure to calibrate pyrgeometers with traceability to SI. One Absolute Cavity Pyrgeometer (ACP95F3) was used to calibrate four pyrgeometers traceable to SI units. Three Eppley PIRs and one Kipp&Zonen CG4 were originally calibrated with traceability to the interim WISG. Using the described procedure below, the responsivity of each pyrgeometer was then adjusted to match the irradiance measured by ACP. Outdoor data was collected during one clear sky nights monitored by the output thermopile voltage of ACP95F3. The irradiance measured by the PIRs was calculated using NREL equation and the CG4 using NREL equation and PMOD/WRC equation. Using the NREL equation, the calculated uncertainty (<i>U</i><sup>95</sup>) of the PIRs varied from 2.43 W/m<sup>2</sup> to 2.67 W/m<sup>2</sup>, and for the CG4 using the NREL equation <i>U</i><sub>95</sub> equals 1.97 W/m<sup>2</sup>, and using the PMOD equation <i>U</i><sub>95</sub> equals 2.88 W/m<sup>2</sup> with respect to SI.

Memristive devices for metrological applications

The EMPIR project 20FUN06 MEMQuD - “Memristive devices as quantum standard for nanometrology” has as one of its fundamental goals the development of technical capability and scientific knowledge for the implementation of a quantum resistance standard based on memristive devices characterized by high scalability down to the nanometer scale, CMOS compatibility and working in air at room temperature. In this work it is presented an overview of the project, highlighted relevant characteristics and working principles of memristive devices and potential applications with focus on metrological application with framing allowed by the last revision of the International System of Units (SI) that is the motivation and background for the aim of this project

Reference Materials of Absorbed Dose: Expanding Dynamic Range and Improving Measurement Accuracy

Establishment and control of metrological characteristics of measurements of absorbed ionizing radiation doses in the range of 0.01 and 200 kGy by reference materials is an urgent task due to their wide application in various industries. The most convenient means of metrological support for transferring a unit of absorbed dose rate of intense photon, electron, and beta radiation to measuring instruments in radiation technologies are reference materials with established metrological traceability to the International System of Units (SI). In the present study, a method for expanding the dynamic range of measuring the absorbed dose of high-intensity ionizing radiation by radiochromic film dosimetry systems was considered and tested. The accuracy (uncertainty) of dose measurements was estimated depending on the initial optical density of the radiation-sensitive layer of the radiochromic composition. The possibility of expanding the dose characteristics and improving the metrological characteristics of the existing reference materials of absorbed dose (in water) for use as secondary standards (Measures) of the absorbed dose of ionizing radiation reproducing and (or) storing one or more points of the selected measurement scale of the absorbed dose with increased accuracy (uncertainty) of the measured values of the absorbed dose (in water) in an extended dynamic range was shown.

Accurate determination of line intensity of H[formula omitted]O near 7181 cm−1 : SI-traceable measurement using primary trace-moisture standard in N[formula omitted] gas

The absorption spectra of trace water vapor in N2 gas with a mole fraction of 500 nmol/mol in the pressure range of 20 kPa to 140 kPa were obtained near 7181 cm−1 using wavelength-meter-controlled cavity ring-down spectroscopy (WMC-CRDS). The reference gas (water vapor in N2 gas) was produced using a generation system of primary measurement standards for trace moisture in gases, where the amount of water vapor was measured using a gravimetric method. The obtained spectra of H2O were analyzed using a multispectrum fitting technique with a speed-dependent asymmetric Voigt profile (SDAVP). The values of the line intensity were determined with traceability to the International System of Units (SI). We could achieve the expanded uncertainty below 2 % for the line intensities of the strong lines.

Calibration and Validation for the Surface Biology and Geology (SBG) Mission Concept: Recommendations for a Multi‐Sensor System for Imaging Spectroscopy and Thermal Imagery

AbstractThe primary objective of the National Aeronautics and Space Administration (NASA) Surface Biology and Geology (SBG) mission is to measure biological, physical, chemical, and mineralogical features of the Earth's surface, realizing a key conceptual component of the envisioned NASA Earth System Observatory (ESO). SBG is planned to launch as a two‐platform mission in the late 2020s, the first of the ESO satellites. Targeted science and applications objectives based on observations of the Earth's SBG helped to define the mission architecture and instrument capabilities for the SBG mission concept. These objectives further drove the need for enabling change detection and trending of surface biological and geological features. These needs implied fundamental calibration goals to achieve the necessary science data quality characteristics. To meet those goals, calibration and validation pre‐launch and on‐orbit methods formed a basis of the calibration and validation concept, including the combined use of on‐board references, vicarious techniques, and routine lunar imaging. International collaboration with space agencies in other countries, an important feature of the recommended SBG mission architecture, uncovered and emphasized the need for inter‐calibration techniques that underscored the importance of collaborative instrument characterization data sharing and the use of common calibration references that are International System of Units (SI) traceable in pre‐launch and post‐launch on orbit calibration mission phases. International collaboration through the use of terrestrial and aquatic networks on six continents for vicarious calibration and validation activities will further assure necessary science data quality while in orbit.

Огляд методів параметричного діагностування агрегатів гідравлічних і паливних систем літальних апаратів

The subject of study in this article is the methods of parametric diagnostics of the technical condition of the units of an air vehicle's hydraulic and fuel systems, which make it possible to ensure the established reliability indicators of these systems throughout their entire life cycle. This work aims to analyze the existing literature on the methods of parametric diagnostics of hydraulic units, determine the basic requirements for the development of diagnostic methods for units of hydraulic, and fuel systems. The objective of the study is to classify the existing methods of parametric diagnostics, applied primarily to hydraulic systems, to analyze the advantages and disadvantages of the algorithms under consideration based on the requirements for diagnostic algorithms established by the authors, and to assess the possibility of effectively using these methodologies to diagnose the technical condition of a complex hydraulic distribution unit. The authors of this work formed the main requirements for the methods of diagnosing a hydraulic and fuel system's units based on the nature of the detected defects, the experience of using diagnostic algorithms, as well as the requirements of existing standards and scientific publications analysis. The authors developed a classification of parametric diagnostic algorithms to systematize existing works. This paper describes the main features and differences between diagnostic algorithms based on methods for identifying a mathematical model of an object and diagnostic algorithms in the space of measured parameters. Methods for forming diagnostic models of hydraulic units have been analyzed, such as the state-space model, the Hammerstein model, the Volterra model, the ARX model, and the matrix of influence coefficients. Established analysis of the application of defect identification algorithms such as a divided difference filter (DDF), a radial basis functions neural network RBF, and a cosine distance method. As a result, the advantages and disadvantages of the monitored diagnostic algorithms were identified and the main tasks for developing an algorithm for parametric diagnostics of the technical condition of a complex hydraulic distribution unit were formulated.

Antiviral Activities of Streptomyces KSF 103 Methanolic Extracts against Dengue Virus Type-2.

Dengue has long been a serious health burden to the global community, especially for those living in the tropics. Despite the availability of vaccines, effective treatment for the infection is still needed and currently remains absent. In the present study, the antiviral properties of the Streptomyces sp. KSF 103 methanolic extract (Streptomyces KSF 103 ME), which consists of a number of potential antiviral compounds, were investigated against dengue virus serotype 2 (DENV-2). The effects of this extract against DENV-2 replication were determined using the quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Findings from the study suggested that the Streptomyces KSF 103 ME showed maximum inhibitory properties toward the virus during the virus entry stage at concentrations of more than 12.5 µg/mL. Minimal antiviral activities were observed at other virus replication stages; adsorption (42% reduction at 50 µg/mL), post-adsorption (67.6% reduction at 50 µg/mL), prophylactic treatment (68.4% and 87.7% reductions at 50 µg/mL and 25 µg/mL, respectively), and direct virucidal assay (48% and 56.8% reductions at 50 µg/mL and 25 µg/mL, respectively). The Streptomyces KSF 103 ME inhibited dengue virus replication with a 50% inhibitory concentration (IC50) value of 20.3 µg/mL and an International System of Units (SI) value of 38.9. The Streptomyces KSF 103 ME showed potent antiviral properties against dengue virus (DENV) during the entry stage. Further studies will be needed to deduce the antiviral mechanisms of the Streptomyces KSF 103 ME against DENV.

Development of a Primary Iridium Solution Standard Traceable to the International System of Units.

The purpose of this work was to develop a primary solution standard for iridium (Ir) that is directly traceable to the International System of Units (SI). The candidate starting material was ammonium hexachloroiridate hydrate, ((NH4)3IrCl6·3H2O), the Ir salt. The SI traceability of the Ir salt was established by the gravimetric reduction (GR) of the salt to the metal under H2. GR traces the results of the analysis directly to the SI base unit of mass, the kg. The GR was also performed on high-purity Ir metal powder, an independent source of Ir, used as a comparison material for the salt. A method for dissolving the Ir metal was developed by modifying information found in the literature. Trace metallic impurities (TMI) analysis was performed on the Ir salt using ICP-OES and ICP-MS. Inert gas fusion (IGF) analysis provided data for the O, N, and H content of the gravimetrically reduced and unreduced Ir metals. The combined results of the TMI and IGF analyses provided the purity data, a required component for the claim to SI traceability. Solution standards were gravimetrically prepared from the candidate SI traceable Ir salt. Solution standards for comparison were prepared from the dissolved, unreduced high-purity Ir metal powder. These solutions were compared by a high-precision ICP-OES method. Agreement in the results between these Ir solutions, with uncertainty estimates calculated by error budget analysis, confirmed the accuracy of the Ir assay in the candidate SI traceable Ir salt, (NH4)3IrCl6·3H2O, thus confirming the concentrations and uncertainties for the primary SI traceable Ir solution standards made from the (NH4)3IrCl6·3H2O.

Design and realization of a mobile-automatic calibration system for ventilator testers: oxygen concentration

Ventilators have a vital role in supplying oxygen to the patients experiencing respiratory failure and ensuring the patient’s oxygen saturation to levels above 50% continuously. Therefore, the accuracy of oxygen concentration measurement becomes very important to assure patient safety obtained by testing the ventilator against a ventilator tester. Testing and calibration laboratory use a ventilator tester for routine calibration of health facilities as well as performance and clinical testing for emergency ventilators that developed massively these days. A mobile-ventilator tester calibration system for oxygen levels, especially for concentrations of 30%, 60%, and 90% according to SNI ISO 80601-2-12:2020, is being developed. This calibration system is designed to operate automatically based on Laboratory virtual instruments engineering workbench (LabVIEW) to control the instrumentation system and perform data acquisition of (oxygen concentration) readings. Three concentrations of oxygen gas reference are stored each on 2 L gas reservoirs to ease the mobilization of the system to testing and calibration laboratory. Hopefully, the traceability to International System of Units (SI) for the ventilator tester can be realized with this calibration system, thus can improve the quality of health services and increase the competitiveness of nationally produced medical devices. Although some improvements are required, the prototype of the calibrator works appropriately as intended.

Research on Design Principle and Process Design of Printed Circuit Board Type Overcurrent Protection Device for Chang’e-4 Popular Science Load Cable

The science popularization load of chang’e-4 is a high-density pressure resistant container with a diameter of 173 mm, a height of 198 mm and a weight of only 2.608 kg. It is loaded with cotton, rape, potato, Arabidopsis, yeast and Drosophila. With the successful landing of chang’e-4, this load has entered the growth and development mode of biological lunar surface. The data interface unit (DIU) of the lander provides the primary bus for the science popularization load system of Chang’e 4. The data interface unit provides no overcurrent protection measures for the power supply output. The science popularization load is provided with the command power supply by the lander system unit (SMU). The current limiting resistance of the power supply output is small, and there is moisture inside the science popularization load. In order to cope with the short circuit of the power supply bus and the command bus caused by the unexpected short circuit of the science popularization load power supply connector, In order to ensure the normal operation of popular science load equipment, the overcurrent protection design is considered on the power supply cable of popular science load.

Evaluation of low-density lipoprotein cholesterol equations by cross-platform assessment of accuracy-based EQA data against SI-traceable reference value.

Low-density lipoprotein cholesterol (LDLC) is the primary cholesterol target for the diagnosis and treatment of cardiovascular disease (CVD). Although beta-quantitation (BQ) is the gold standard to determine LDLC levels accurately, many clinical laboratories apply the Friedewald equation to calculate LDLC. As LDLC is an important risk factor for CVD, we evaluated the accuracy of Friedewald and alternative equations (Martin/Hopkins and Sampson) for LDLC. We calculated LDLC based on three equations (Friedewald, Martin/Hopkins and Sampson) using the total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDLC) in commutable serum samples measured by clinical laboratories participating in the Health Sciences Authority (HSA) external quality assessment (EQA) programme over a 5years period (number of datasets, n=345). LDLC calculated from the equations were comparatively evaluated against the reference values, determined from BQ-isotope dilution mass spectrometry (IDMS) with traceability to the International System of Units (SI). Among the three equations, Martin/Hopkins equation derived LDLC had the best linearity against direct measured (y=1.141x-14.403; R2=0.8626) and traceable LDLC (y=1.1692x-22.137; R2=0.9638). Martin/Hopkins equation (R2=0.9638) had the strongest R2 in association with traceable LDLC compared with the Friedewald (R2=0.9262) and Sampson (R2=0.9447) equation. The discordance with traceable LDLC was the lowest in Martin/Hopkins (median=-0.725%, IQR=6.914%) as compared to Friedewald (median=-4.094%, IQR=10.305%) and Sampson equation (median=-1.389%, IQR=9.972%). Martin/Hopkins was found to result in the lowest number of misclassifications, whereas Friedewald had the most numbers of misclassification. Samples with high TG, low HDLC and high LDLC had no misclassification by Martin/Hopkins equation, but Friedewald equation resulted in ∼50% misclassification in these samples. The Martin/Hopkins equation was found to achieve better agreement with the LDLC reference values as compared to Friedewald and Sampson equations, especially in samples with high TG and low HDLC. Martin/Hopkins derived LDLC also enabled a more accurate classification of LDLC levels.