Concentration Measurements Research Articles

Blood ammonia concentration measurement – effects of sampling site and cirrhosis during induced hyperammonaemia

BackgroundAmmonia is implicated in hepatic encephalopathy (HE) and prognostic in cirrhosis. Venous ammonia concentration, yielding similar correlation with HE grades as arterial, has become the preferred practise but comparative data are limited.AimTo quantify effect of sampling site on ammonia concentration in healthy persons and patients with cirrhosis.MethodsAmmonia concentrations were measured by arterial and femoral venous blood sampling in ten healthy men and ten male patients with cirrhosis before and during hyperammonaemia induced by ammonia infusion. Cubital vein samples were included during the infusion.ResultsAt baseline, arterial-venous concentration gaps were similar (p = 0.15) in healthy persons [14 (10–19) and 8 (4–12) µmol/L] and patients with cirrhosis [53 (32–74) and 40 (23–57) µmol/L]. Ammonia infusion increased arterial-venous concentration gaps in both groups [115 (97–133) and 61 (31–90) vs. 175 (123–227) and 134 (65–203) µmol/L]. Mean ammonia concentration difference between groups during hyperammonaemia was 72 (42–103) µmol/L (p < 0.001) and independent of sampling site. Cubital and femoral vein concentrations were comparable (p = 0.26). In cirrhosis, calculated upper limit normal values (ULN) were comparable for arterial and venous blood at baseline [2.0 (1.2–2.8) and 2.1 (1.2–3.0), p = 0.74] and during hyperammonaemia [6.7 (4.7–8.7) and 6.2 (4.4– 8.1), p = 0.44].ConclusionsWe found clinically meaningful intra-individual arterial-venous concentration gaps in both healthy persons and patients with cirrhosis at any ammonia concentration. Inter-group concentration differences after induced hyperammonaemia were relatively constant across sampling sites which supports clinical use of venous sampling. ULN-normalised ammonia concentrations were valid for both arterial and venous sampling.

Keystone taxa drive the synchronous production of methane and refractory dissolved organic matter in inland waters

The production of both methane (CH4) and refractory dissolved organic matter (RDOM) depends on microbial consortia in inland waters, and it is unclear yet the link of these two processes and the underlying microbial regulation mechanisms. Therefore, a large-scale survey was conducted in China's inland waters, with the measurement of CH4 concentrations, DOM chemical composition, microbial community composition, and relative environmental parameters mainly by chromatographic, optical, mass spectrometric, and high-throughput sequencing analyses, to clarify the abovementioned questions. Here, we found a synchronous production of CH4 and RDOM linked by microbial consortia in inland waters. The increasing microbial cooperation driven by the keystone taxa (mainly Fluviicola and Polynucleobacter) could promote the transformation of labile DOM into RDOM and meanwhile benefit methanogenic microbial communities to produce CH4. As such, CH4 and RDOM showed consistent spatial differences, which were mainly influenced by total nitrogen and dissolved oxygen concentrations. This finding deepened the understanding of microbial-driven carbon transformation and will help to more accurately evaluate the carbon source-sink relationship in inland waters.

Advancing the C[formula omitted] low-temperature oxidation chemistry through species measurements in a rapid compression machine, Part A: 1-Butene

Alkene chemistry plays a crucial role in the autoignition and oxidation of larger hydrocarbons. Unlike its other isomers, 1-butene is characterized by a two-stage ignition process. Various previous studies of 1-butene oxidation have used experimental techniques, including the measurement of ignition delay times in rapid compression machines (RCM) and in shock tubes, the determination of flame velocities, and the measurement of species concentrations in flames and in jet-stirred reactors (JSR). JSR studies provide an important insight into intermediate species formation at low temperatures but are constrained to low pressures and/or highly diluted conditions. To bridge the gap between JSR and engine-relevant conditions, this study presents species concentration measurements during the oxidation of 1-butene at 733 K and 30 bar under stoichiometric ’air-like’ conditions in an RCM, complemented by IDT measurements in the temperature range of 680–910 K. We designed an innovative 2-valve sampling setup to reduce quantitative uncertainties and the time required for species measurements. Our results indicate that existing 1-butene models fail to accurately predict the IDTs and the formation of the key oxidation intermediates. In response, potential optimizations for an improved kinetic model based on NUIGMech1.3 are discussed. Rate parameters for predominantly fuel consumption pathways, along with other reactions and thermochemical properties in the Waddington mechanism, have been altered within expected uncertainty limits to reflect the experimentally observed IDTs and species concentrations of this study and other validation data from the literature. However, the refined model does not predict the formation of 2-ethenyloxirane and ethene, indicating a gap in our understanding of the chemistry of these components. Overall, this study demonstrates the importance of measuring intermediates under the same conditions as IDTs to accurately address deficiencies in current kinetic mechanisms, and represents the first phase of a comprehensive investigation advancing the understanding of C4 oxidation chemistry.Novelty and significance statementThe novelty of this research lies in the design of an innovative sampling system for RCM species measurements, lowering the time for experimental execution and the uncertainties of the measurements. This enabled first-time species measurements during the oxidation of butene isomers in an RCM at high pressure and low level of dilution, contributing to the refinement of the 1-butene sub-mechanism within the NUIGMech1.3 framework. This research contributes to the understanding of the oxidation of alkenes, an important class of intermediates in gasoline and biofuel combustion. It emphasizes the need to measure intermediate species at the same conditions as ignition delay times, which are essential for understanding oxidation pathways under engine-relevant conditions. This research is part of a broader investigation of C4 oxidation chemistry, along with our companion work on n-butane. The resulting kinetic model is capable of reproducing most of the available n-butane and 1-butene validation targets.

Plasma Concentration as a Proxy for Perilymph Drug Levels: Preclinical and Clinical Dexamethasone Measures with a Long-Acting Formulation for Precise Delivery to the Round Window Membrane.

To use animal pharmacokinetic data and FluidSIM modeling to estimate human dexamethasone perilymph concentrations from plasma concentration measurements over time following a single intratympanic administration of SPT-2101. Perilymph and plasma dexamethasone concentrations were measured in guinea pigs and African green monkeys over 3 to 6 weeks post-intratympanic administration of SPT-2101. Plasma concentrations of dexamethasone were measured in Ménière's disease patients post-intratympanic administration of SPT-2101. FluidSIM was trained on the correlations of animal plasma and animal perilymph levels, allowing the human perilymph drug time course for SPT-2101 to be predicted from measured human plasma dexamethasone concentrations. Tertiary care neurotology clinic in Perth, Australia. Nine adults with unilateral definite Ménière's disease per Barany Society criteria. Intratympanic SPT-2101, a single injection of a long-acting gel formulation of dexamethasone precisely delivered at the round window. Estimated dexamethasone levels in human perilymph following a single administration of SPT-2101 at the round window over time. Perilymph dexamethasone concentrations were above estimated therapeutic levels for up to 35 days in guinea pigs and at least 21 days in African green monkeys. In human subjects, plasma dexamethasone concentrations were detected for 2 weeks post-administration. Animal middle ear, plasma and perilymph drug interrelationships were compared to FluidSIM simulations, providing rationale for correlating dexamethasone concentrations in the respective compartments. Comparable simulations of human plasma concentrations predicted perilymph dexamethasone therapeutic levels in humans for 23-55 days. Sustained release dexamethasone from SPT-2101 precisely delivered at the round window provides prolonged and durable estimated perilymph concentrations in clinical subjects.

Enhancing Uncrewed Aerial Vehicle Techniques for Monitoring Greenhouse Gas Plumes at Point Sources

The urgency of the global climate crisis necessitates advanced monitoring of greenhouse gases, with an emphasis on capturing their spatial and temporal variability. This study explores techniques to enhance plume detection and concentration measurements using uncrewed aerial vehicles (UAVs) for monitoring at point sources, specifically at an incineration stack. Through preliminary site investigations, our approach employed strategically designed flight paths and an autopilot system to optimize flight operations within the constraints of limited flight time due to battery capacity. We combined a UAV-mounted anemometer with a plume rise model to localize the plume center at a distance of 30 m from the stack center and evaluated its performance by comparing the model-based estimations at different altitudes and angular directions with the observation results. The comparison demonstrated that the results obtained by localizing the plume center using a plume rise model and a UAV-mounted anemometer aligned well with observations based on CO2 concentration analysis. The comparative analysis showed a RMSE of 8.44 m and a MAE of 7.26 m for altitude, and a RMSE of 32.31∘ and a MAE of 25.78∘ for angular direction. Furthermore, we assessed the effectiveness of hovering UAV flights, in which a UAV remains stationary at a fixed point in the air, compared to non-hovering flights in capturing pollutant concentration. While both methods performed similarly in detecting the plume center, non-hovering flights underestimated the CO2 concentration due to insufficient time for measurement despite a sensor response time of less than three seconds. Overall, our proposed hybrid monitoring strategy integrates non-hovering and hovering flights, enhancing both plume detection efficiency and concentration measurement accuracy at point sources.

Copper and zinc status in cord blood and breast milk and child's neurodevelopment at 18 months: Results of the Italian PHIME cohort

BackgroundTrace elements, including zinc (Zn) and copper (Cu), although toxic at higher concentrations are known to play important roles in the maintenance of human health and neurodevelopment. Few epidemiological studies have investigated the association between prenatal or early postnatal Cu and Zn levels and child neurodevelopment. The aim of this research is to assess the association between child neurodevelopment at 18 months of age and cord blood and breast milk concentrations of Cu and Zn in Italian mother-child pairs enrolled in the Italian Northern Adriatic Cohort II (NAC-II), a part of the “Public health impact of long-term, low-level, mixed element exposure in susceptible population strata” project PHIME. MethodsThe study population consisted of 632 children, and their mothers, born within the NAC-II, who were tested with the Bayley Scales of Infant and Toddler Development third edition (BSID-III) at age 18 months. Cu and Zn concentrations were measured in cord blood and breast milk samples. Only children born at term (≥37 gestational week), who completed the BSID-III test and had at least 1 measure of Cu and Zn concentrations were included in the analysis. Information about socio-demographics and lifestyles were collected through questionnaires at different phases of follow-up. Cu and Zn concentrations were log2 transformed because of their skewed distribution. Multiple linear regression models were performed to study the association between each BSID-III composite score (cognitive, motor and language) and each metal concentration. Separate models were applied for each biological sample. The β coefficient (β) and its 95% confidence interval (95% CI) were estimated. Stratified analyses by child's sex were also conducted. ResultsThe mean ± standard deviation (SD) of cognitive, motor and language composite scores were respectively: 106 ± 8, 101 ± 5 and 97 ± 8. The mean ± SD of Cu and Zn concentrations (ng/g) were respectively 699.2 ± 129.0 and 2538 ± 589 in cord blood and 607 ± 498 and 3226 ± 1428 in breast milk. No association between metal concentration and cognitive composite score was found. A higher motor composite score was associated with higher Cu concentrations in cord blood (β = 4.31 95% CI 2.03; 6.59). No associations were found between language composite score and metal concentrations. The effect of Cu cord blood concentration on motor composite score was confirmed when stratified by sex: males (β = 5.49 95% CI 2.15; 8.36) and females (β = 3.11; 95% CI 0.00; 6.22). A direct association, in females only, was found between language composite score and Cu concentration in cord blood (β = 5.60 95% CI 0.63; 10.57) and in breast milk (β = 3.04 95% CI 1.06; 5.03), respectively. ConclusionThe results from this cohort study showed a strong direct association between prenatal Cu levels and child motor neurodevelopment at 18 months. However, for generalizability, future research on the effects of Zn and Cu on neurodevelopment should include a larger range of early-life concentration of trace elements.

Nifedipine May Be an Inhibitor of Clozapine Metabolism, as Seen in 5 Patients: 2 from a US Double-Blind Study and 3 from a German TDM Study

Background: Clozapine is the only licensed antipsychotic for treatment-refractory schizophrenia. Therapeutic drug monitoring (TDM) refers to the measurement of clozapine concentration. Clozapine TDM can be used to optimize treatment, particularly by identifying pharmacokinetic interactions between clozapine and comedications. Methods: We identified 5 cases of patients with available clozapine concentrations who were concomitantly receiving nifedipine and clozapine. These cases were drawn from 2 independent datasets: 2 from a double-blind, randomized clinical trial in the United States and 3 from a German TDM naturalistic database. As an index of clozapine clearance, we used the trough-level concentration-to-dose (C/D) ratios to estimate the minimum therapeutic doses. To estimate dose-correction factors for nifedipine treatment, we included only clozapine concentrations at steady state. We divided the clozapine minimum therapeutic doses (MTD) from the on-condition by the off-nifedipine condition. Results: In 4 patients, the ratio of on/off nifedipine for MTD ranged between 0.58 and 0.82. Another patient had no data and had to be compared with published control data (female smoker of African ancestry), providing a correction factor of 0.52 after eliminating 5 concentrations contaminated by the development of obesity. Conclusions: In the absence of access to TDM, when prescribing nifedipine to clozapine-treated patients, we recommend reducing the daily dose of clozapine by one-third because of the weak inhibition of clozapine metabolism. With access to TDM, TDM should guide dosing as unusual patients may need larger dose reductions, as it is possible that in some patients, nifedipine may be a moderate inhibitor requiring halving clozapine dose. Further prospective studies are warranted.

Current status of serum lithium concentration measurement in Japan.

Current status of serum lithium concentration measurement in Japan.

Modelling of Carbon Monoxide and Suspended Particulate Matter Concentrations in a Rural Area Using Artificial Neural Networks

Air pollution is a growing concern in rural areas where agricultural production can be reduced by it. This article analyses data obtained as part of a research project. The aim of this study is to understand the influence of atmospheric pressure, air temperature, air relative humidity, longitude and latitude of the location, and indoor and outdoor environment on local rural workplace diversity of air pollutants such as carbon monoxide (CO) and suspended particulate matter (SPM), as well as the contribution of these variables to changes in such air pollutants. The focus is on four topics: motivation, innovation and creativity, leadership, and social responsibility. Furthermore, this study developed an artificial neural network (ANN) model to predict CO and SPM concentrations in the air based on data collected from the mentioned inputs. The related sensors were assembled on an Arduino Mega 2560 board to form a field-portable device to detect air pollutants and meteorological parameters. The sensors included an MQ7 sensor for CO concentration measurement, a Sharp GP2Y1010AU0F dust sensor for SPM concentration measurement, a DHT11 sensor for air temperature and air relative humidity measurement, and a BMP180 sensor for air pressure measurements. The longitude and latitude of the location were measured using a smartphone. Measurements were conducted from 20 December 2021 to 16 July 2022. Results showed that the overall average outdoor CO and SPM concentrations were 10.97 ppm and 231.14 μg/m3 air, respectively. The overall average indoor concentrations were 12.21 ppm and 233.91 μg/m3 air for CO and SPM, respectively. Results showed that the ANN model demonstrated acceptable performance in predicting CO and SPM in both the training and testing phases, exhibiting a coefficient of determination (R2) of 0.575, a root mean square error (RMSE) of 1.490 ppm, and a mean absolute error (MAE) of 0.994 ppm for CO concentrations when applying the testing dataset. For SPM concentrations, the R2, RMSE, and MAE using the test dataset were 0.497, 30.301 μg/m3 air, and 23.889 μg/m3 air, respectively. The most influential input variable was air pressure, with contribution rates of 22.88% and 22.82% in predicting CO and SPM concentrations, respectively. The acceptable performance of the developed ANN model provides potential advances in air quality management and agricultural planning, enabling a more accurate and informed decision-making process regarding air pollution. The results of short-term estimation of CO and SPM concentrations suggest that the accuracy of the ANN model needs to be improved through more comprehensive data collection or advanced machine learning algorithms to improve the prediction results of these two air pollutants. Moreover, as even lower cost devices can predict CO and SPM concentrations, this study could lead to the development some kind of virtual sensor, as other air pollutants can be estimated from measurements of particulate matters.

The Single-Dose Pharmacokinetics of a Compounded Levetiracetam Formulation and Bioequivalence to a Commercial Formulation in Healthy Dogs.

Levetiracetam (LEV) is an anti-epileptic drug used extra-label in dogs. Commercially available extended-release formulations (LEV-ER), administered twice daily, cannot be crushed or split, limiting their use in small dogs. A compounded LEV-ER formulation (PO-COMP) can purportedly be partitioned without loss of extended-release properties. The aims of this study were to establish the pharmacokinetic parameters of PO-COMP, divided at the tablet score, and determine the bioequivalence of partitioned PO-COMP to an intact commercially available Food and Drug Administration-approved human oral generic formulation of LEV-ER (PO-COMM). In a randomized crossover design, 12 healthy dogs received a single IV dose (30 mg/kg) of IV-COMM, a single oral dose (500 mg) of intact PO-COMM, or a single oral dose (500 mg) of partitioned PO-COMP and underwent serial measurement of plasma LEV concentrations over 24 h. PO-COMP was bioequivalent to PO-COMM using the 90% confidence interval method for maximum concentration (-3.2% difference [CI -7.4% to -1.1%]) and area under the curve (-14.4% difference [CI -17.8% to 10.8%]). PO-COMP may improve medication adherence and seizure control relative to immediate-release LEV, which requires three times daily dosing. Efficacy studies of PO-COMP are warranted.

Single-Molecule Detection of Serum MicroRNAs for Medulloblastoma with Biphasic Sandwich Hybridization-Assisted Plasmonic Resonant Scattering Imaging.

MicroRNA (miRNA) dysregulation is closely related to the occurrence and progression of medulloblastoma (MB). However, the full potential of serum circulating miRNAs in MB diagnosis is restricted by their ultralow abundance in peripheral blood due to blood-brain barrier. Here, we report the direct preamplification-free detection of aberrant expression of oncogenic miRNAs in serum from MB patients by proposing a simple yet robust single-molecule assay that combines biphasic sandwich hybridization in nucleic acids and the dark-field single-particle plasmonic imaging (B2S2PI). In this strategy, signal DNA was prehybridized with target miRNA in homogeneous solution to form sDNA-RNA complexes. Then the captured DNA strands with rationally adjusted surface densities could efficiently capture the sDNA-RNA complexes to generate a well-separated DNA-RNA sandwich structure. The combination of homogeneous and heterogeneous reactions enabled interface-mediated hybridization reactions to maintain molecular stability with fewer bases, making it suitable for the direct amplification-free assays of short miRNA targets. Labeling the DNA-RNA hybrids with plasmatic gold nanotags allowed nondestructive recognition and imaging of individual miRNA targets under mild conditions with high signal-to-noise ratio. By digitally counting and analyzing the bright plasmonic resonant scattering spots, B2S2PI enabled both the measurement of a low femtomolar concentration of circulating miRNA-21 in 5 μL sample volume within a turnaround of 2 h and the discrimination of single base mismatches. Moreover, B2S2PI was universal for detecting miRNAs with different sequences and secondary structures. Further analysis of clinical serum samples revealed that B2S2PI was capable of accurately distinguishing MB patients from noncancer controls with an area under the curve (AUC) of 0.99, which was superior to that of qRT-PCR. B2S2PI holds promise as a novel alternative means for single-molecule miRNA assay and sheds light on the circulating nucleic acid-based liquid biopsy of intracranial malignant tumors.

Monitoring of tritium concentrations in tap water and rainwater collected in Thailand.

This study aimed to measure tritium (3H) concentrations in Thailand. Nationwide tap water samples were collected in July 2021. Rainwater samples were collected monthly during May-October 2020, April-October 2021, and February-March 2022 in Chonburi province and in Chiang Mai province during July-November 2021, January 2022, and March-June 2022. The measurements of 3H activity concentrations were conducted by Osaka Sangyo University (OSU) and were compared with measurements by the Thailand Institute of Nuclear Technology (TINT). The results from OSU and TINT showed that 3H concentrations in tap water were matched in the ranged from 0.08±0.03 to 0.28±0.04BqL-1, while those in rainwater samples collected from Chonburi province and Chiang Mai province are also matched in the ranged from 0.11±0.02 to 0.21±0.03BqL-1 and 0.19±0.02 to 0.57±0.04BqL-1, respectively. Our measured result suggests that 3H concentration in tap water and rainwater shows a similar relation depending on latitude.

Pt/MOF-5 film-coated optical micro-nano fibre hydrogen sensor with humidity and temperature compensation functions

In this paper, a composite fibre structure based on thin-core fibre (TCF), Fibre Bragg grating (FBG), and micro-nano fibre (MNF) is proposed to achieve simultaneous sensing of humidity, temperature, and hydrogen concentration by coating different functional films. Based on surface plasmon resonance (SPR), a TCF and Au/PVA film are combined to achieve relative humidity (RH) measurement. Pt/MOF-5 is coated on the surface of the MNF by in-situ growth method. Its refractive index (RI) is changed by absorbing hydrogen. In temperature detection, FBG realizes the temperature compensation. Based on the above sensing mechanisms, it is shown that the fibre has a RH sensitivity of 0.38 nm/%RH, a temperature sensitivity of −0.0497 nm/°C, and a hydrogen sensitivity of 0.541 nm/%. The Bragg grating has a temperature sensing sensitivity of 0.0106 nm/°C, which accurately compensates for temperature crosstalk. This composite structure provides a good application prospect for accurate measurement of hydrogen concentration.

Improving methods for sample preparation of biological fluids by inductively coupled plasma mass spectrometry

This study presents the results of analyzing biological fluids using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after applying various sample preparation methods. Optimal conditions for preparing biological fluids have been identified, which help minimize matrix effects and improve measurement accuracy. The most effective methods were selected considering the specifics of matrices and their interactions with analytical equipment. The study evaluated the contributions of spectral interferences to the analytical signal when using ICP-MS. It was found that the physical properties of acid solutions, such as viscosity, surface tension, density, and volatility, significantly affect the analysis results, introducing additional interferences and data distortions. The use of internal standards to eliminate spectral interferences was investigated. Criteria for choosing internal standards were established based on proximity to ionization potentials and mass characteristics, which allows for more accurate result correction and minimizes interference effects. Additionally, it was discovered that polyatomic ions play a significant role in enhancing analyte signals. This influence is due not to the background levels of elements in the samples or reagents, but to ions formed from matrix components in the samples. The study demonstrated that isobaric interferences caused by polyatomic ions significantly impact analytical accuracy. These findings contribute to improving sample preparation and analysis methods for biological fluids using ICP-MS, leading to more reliable and accurate measurements of element concentrations.

Balloon Baseline Stratospheric Aerosol Profiles (B2SAP)—Perturbations in the Southern Hemisphere, 2019–2022

AbstractVolcanic and pyrocumulonimbus (pyroCB) injections into the stratosphere perturb the aerosol layer and can have important radiative and chemical impacts on timescales spanning from months to several years. Repeated in situ balloon‐borne measurements of aerosol size and number concentration (&gt;140 nm in diameter), ozone, water vapor, and atmospheric state variables made at midlatitudes in the southern hemisphere (SH) since 2019 enable us to better characterize such events. We use this record and coincident lidar extinction profiles to study several moderate to large stratospheric perturbations in the SH between 2019 and 2022 in detail, including the Australian New Year Super Outbreak (ANYSO) pyroCB in 2020. Median vertical profiles of aerosol number concentration, effective radius, and surface area in SH midlatitudes are also compared with those recorded in Northern Hemisphere midlatitudes under baseline conditions using an identical payload. These data depict the variability in stratospheric aerosol properties in the SH midlatitudes during this period and provide a benchmark for global sectional aerosol models. They reveal that sulfate particle size distributions under baseline conditions and in volcanic plumes are relatively well represented in the Community Earth System Model—Community Aerosol Radiation Model for Atmospheres (CESM‐CARMA), but more observations of biomass burning plumes are needed to improve model skill in simulating pyroCB. Comparisons between in situ and lidar observations also highlight a need for more observations of aerosol composition and refractive index in both fresh and aging biomass burning plumes.

Adding More Shape to Nanoscale Reference Materials─LiYF4:Yb,Tm Bipyramids as Standards for Sizing Methods and Particle Number Concentration.

The increasing industrial use of nanomaterials calls for the reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry, and test and reference materials (RMs) with sizes and shapes, closely matching real-world nonspheric nano-objects. An efficient strategy to minimize efforts in producing nanoscale RMs (nanoRMs) for establishing, validating, and standardizing methods for characterizing nanomaterials are multimethod nanoRMs. Ideal candidates are lanthanide-based, multicolor luminescent, and chemically inert nanoparticles (NPs) like upconversion nanoparticles (UCNPs), which can be prepared in different sizes, shapes, and chemical composition with various surface coatings. This makes UCNPs interesting candidates as standards not only for sizing methods, but also for element-analytical methods like laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), quantitative bioimaging methods like X-ray fluorescence computed tomography (XFCT), and luminescence methods and correlative measurements. Here, we explore the potential of two monodisperse LiYF4:Yb,Tm bipyramids with peak-to-peak distances of (43 ± 2) nm and (29 ± 2) nm as size standards for small-angle X-ray scattering (SAXS) and tools for establishing and validating the sophisticated simulations required for the analysis of SAXS data derived from dispersions of nonspheric nano-objects. These SAXS studies are supplemented by two-dimensional (2D)-transmission electron microscopy measurements of the UCNP bipyramids. Additionally, the particle number concentration of cyclohexane dispersions of these UCNP bipyramids is determined by absolute SAXS measurements, complemented by gravimetry, thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectrometry (ICP-OES). This approach enables traceable particle number concentration measurements of ligand-capped nonspheric particles with unknown chemical composition.

International intercomparison of Radon 222 activity concentration calibration facilities

The Coalition of International Radon Associations (COIRA) organised an inter-comparison of Rn-222 (radon) activity concentrations reported by calibration laboratories. A set of three AlphaGUARDs were used as transfer reference instruments against which to compare reported Rn-222 activity concentrations. Rn-222 activity concentration calibration facilities (sometimes termed chambers) from seven countries (Australia, US, Czech Republic, Spain, England, Sweden, Canada), and three continents participated in this project. The objective of the study was to provide information useful to calibration chamber operators and public health officials in the improvement of measurement and control systems, the maintenance of performance standards for measurements, and regulatory requirements for calibrations. This work builds upon and expands previous interlaboratory comparisons and provides data for estimating and using calibration uncertainty values as part of overall field error estimates and limits. A simple proportional difference between laboratories is presented here, calculated as the average for N hours of each hour’s difference between the laboratory’s concentration and the average of the three reference instruments. This percent difference ranged from less than 0.5% to just less than 8%. This work demonstrates that the ANSI/AARST standards limit of 8% for the estimated unexpanded (one sigma) individual calibration estimated uncertainty for continuous radon monitor calibration facilities in the US is achievable. However, given the few standards regarding calibration of Rn-222 activity concentration measurement instruments that themselves are often used to calibrate secondary and tertiary Rn-222 calibration facilities, there is a great need for continued interlaboratory comparisons to harmonise and document the calibration of Rn-222 activity concentrations.

High-precision ethanol concentration microsensor with global spectra aided by the multi-layer perceptron

Whispering gallery mode (WGM) resonators can be used for precision measurement thanks to their high sensitivity, small size, and fast response time. Nevertheless, the design of such sensors is usually achieved by selecting a typical single-mode tracking method, which leads to low utilization of a great deal of information in the resonance spectrum and affects the precision. Here, we use the multi-layer perceptron (MLP) deep learning algorithm to train the global spectra and realize the high-precision measurement of ethanol concentration. Firstly, a large number of transmission spectra of different ethanol concentrations are collected and directly used as the original data sets. Secondly, the MLP algorithm is used for training and testing. Finally, the local feature dimension is extracted from the global features of the spectrum for prediction. The results show that the prediction accuracy of the global spectra sensing is 99.81%, which is 13.02% higher than that of extracting 10 local features. In addition, the prediction accuracy of the MLP is compared with four other commonly used machine learning (ML) algorithms, and the results show that the MLP algorithm has the highest prediction accuracy. Therefore, the high-precision ethanol concentration sensor proposed in this paper opens a new way for intelligent optical micro-resonator sensing.

River plume identification through a deep-learning model: an innovative approach

ABSTRACT River plumes are complex physical phenomena that occur at the interface between riverine and marine systems. The lack of direct measurements of sediment concentration complicates the study of these geomorphological features, since the boundaries of river plumes are often gradual and unclear. Therefore, the identification and digitalization of river plumes is not simple and the methods applied in different study areas are not always objective and replicable. The aim of this work is to provide a valid approach based on a deep-learning model that uses Convolution Neural Network (CNN) layers for the digitalization of river plumes. We describe the methodology applied to implement the input dataset used for training the model, the errors obtained, and an application for a study area of about 300 km located in the Mediterranean. The model uses Sentinel-2 Level-1C images. The application of the model to a specific study area allowed us to understand the possibility of investigating these geomorphological features to obtain results in agreement with previous works. As a matter of fact, by using the red band as a proxy of sediment concentration, we were able to investigate the average behaviours of sediment dispersion along the coast and to extract innovative data related to specific events for the study of morphological characteristics such as dimension and direction.

Study on the impact of humidity on dust dispersion in open-pit mining under different environmental temperatures

To investigate the impact of changes in environmental temperature and humidity on the dust migration patterns during the open-pit mining and loading process, a 1:1 simulation model of open-pit mining and loading was established using SCDM software, based on actual working conditions. Fluent software was used to study the airflow velocity field and dust migration patterns under different temperature and humidity conditions. The simulation results were validated by on-site measurements of dust concentration, with the error values at selected measurement points all within 20%. The results indicate that as relative humidity increases, the dust dispersion capacity decreases, with a more significant reduction in high-temperature environments. Dust concentration is higher in the plane at heights of 3 m to 6 m, and dust tends to accumulate within a range of approximately 10–15 m around the ore transport vehicle. As relative humidity increases from 20% to 80%, the dust concentration within the height range of 3–6 m gradually decreases. At lower environmental temperatures, dust is less likely to settle and tends to move upwards above 6 m. As the environmental temperature increases, dust tends to settle near the ore transport vehicle.