Volumetric Sampling Research Articles

Airborne microplastic monitoring: Developing a simplified outdoor sampling approach using pollen monitoring equipment

A novel, yet simple, airborne microplastic (MP) sampling approach using global pollen monitoring equipment was applied to identify, characterise and quantify outdoor airborne MPs for the first time. Modification of Burkard spore trap tape adhesive provided particle capture and facilitated downstream spectroscopy analysis. 36 polymer types were identified from a total of 21 days sampling using Burkard spore traps at two locations (United Kingdom and South Africa). MPs were detected in 95 % of daily samples. Mean MP particle levels were 2.0 ± 0.9 MP m-3 (11 polymer types) in Hull (U.K.), during March, 2.9 ± 2.0 MP m-3 (16 types) in Hull in July, and 11.0 ± 5.7 MP m-3 (29 types) in Gqeberha, (S.A.) in August 2023. The most abundant polymer type was nylon (Gqeberha). The approach was compared with two passive sampling methods whereby 27 polymer types were identified and of these, 6 types were above the limit of quantification (LOQ), with poly(methacrolein:styrene) (PMA/PS) the most abundant. Irregularly shaped MPs < 100 µm in length were predominant from all sampling approaches. For the first time, airborne MPs were chemically characterised and quantified using volumetric pollen sampling equipment, representing a viable approach for future airborne MP monitoring.

Lensless Mueller holographic microscopy with robust noise reduction for multiplane polarization imaging

Lensless holographic microscopy has emerged as a powerful and cost-effective tool for computational imaging, offering high resolution over a large field of view, beneficial for various biological applications. However, conventional approaches can struggle with contrast and accurate visualization of diverse components over the samples, which can directly affect the diagnostic precision of the techniques. Mueller imaging, while offering detailed, stain-free observations of polarized light responses in samples, often has a limited field of view and single plane information. This is due to the use of high NA microscope objectives and generally complex hardware setups, thus narrowing its practical effectiveness. This work introduces a Lensless Mueller Holographic Microscopy (LMHM) system that overcomes these limitations, enabling large field of view, volumetric multi-layer imaging, and Mueller matrix computation using in-line lens-free holography setup. The proposed system provides precision visualization of polarization information in samples, offering high-quality features due to the incorporation of a numerical multi-height Gerchberg-Saxton reconstruction algorithm with additional complex field filtering and a physical rotating diffuser. The proposed LMHM framework is validated with a calibrated USAF 1951 birefringent test target. A multiplane sample containing cloth fiber is utilized to study the LMHM capabilities of imaging volumetric samples. Finally, the LMHM is used to analyze two mice’s brain slices, effectively showcasing this organ’s anatomy. Among other structures in the brain, the proposed method easily allows the visualization of, e.g., the corpus callosum. These results constitute a proof-of-concept evaluation for bioimaging applications.

Auditing the microbiological quality of the air in operating theatres.

The critical relationship between airborne microbiological contamination in an operating theatre and surgical site infection (SSI) is well known. The aim of this annotation is to explain the scientific basis of using settle plates to audit the quality of air, and to provide information about the practicalities of using them for the purposes of clinical audit. The microbiological quality of the air in most guidance is defined by volumetric sampling, but this method is difficult for surgical departments to use on a routine basis. Settle plate sampling, which mimics the mechanism of deposition of airborne microbes onto open wounds and sterile instruments, is a good alternative method of assessing the quality of the air. Current practice is not to sample the air in an operating theatre during surgery, but to rely on testing the engineering systems which deliver the clean air. This is, however, not good practice and microbiological testing should be carried out routinely during operations as part of clinical audit.

Three-dimensional radial echo-planar spectroscopic imaging for hyperpolarized 13C MRSI in vivo.

To demonstrate the feasibility of 3D echo-planar spectroscopic imaging (EPSI) technique with rapid volumetric radial k-space sampling for hyperpolarized (HP) 13C magnetic resonance spectroscopic imaging (MRSI) in vivo. A radial EPSI (rEPSI) was implemented on a 3 T clinical PET/MR system. To enable volumetric coverage, the sinusoidal shaped readout gradients per k-t-spoke were rotated along the three spatial dimensions in a golden-angle like manner. A distance-weighted, density-compensated gridding reconstruction was used, also in cases with undersampling of spokes in k-space. Measurements without and with HP 13C-labeled substances were performed in phantoms and rats using a double-resonant 13C/1H volume resonator with 72 mm inner diameter. Phantom measurements demonstrated the feasibility of the implemented rEPSI sequence, as well as the robustness to undersampling in k-space up to a factor of 5 without advanced reconstruction techniques. Applied to measurements with HP [1-13C]pyruvate in a tumor-bearing rat, we obtained well-resolved MRSI datasets with a large matrix size of 123 voxels covering the whole imaging FOV of (180 mm)3 within 6.3 s, enabling to observe metabolism in dynamic acquisitions. After further optimization, the proposed rEPSI method may be useful in applications of HP 13C-tracers where unknown or varying metabolite resonances are expected, and the acquisition of dynamic, volumetric MRSI datasets with an adequate temporal resolution is a challenge.

Monitoring of three-dimensional live-cell cultures using a multimode, multiscale imaging system combining confocal fluorescence microscopy and optical coherence microscopy

Live-cell monitoring involves long-term observation and analysis of living cells in tissue cultures, which develop cells or tissues in an artificial environment and are essential for tissue engineering. Fluorescence microscopy (FM) is widely used as a monitoring tool owing to its powerful ability to visualize protein distribution within cells and tissues, thereby providing information on their functions in biological processes. To reduce the photobleaching effect, which is a major limiting factor in FM, FM is generally combined with other imaging modalities, such as phase contrast and differential interference contrast microscopy, which are nondestructive to fluorochromes, to selectively use fluorescence signals only in specific areas of interest within a sample. However, these methods are restricted to thin samples and cannot produce depth-resolved images. Here, we propose a method to determine three-dimensional (3D) positions in volumetric samples for application in high-resolution 3D fluorescence imaging using a multimode and multiscale imaging system that combines optical coherence microscopy (OCM) and line confocal FM (LC–FM). We also demonstrate the benefits of multimodal imaging in 3D cell culture monitoring. To evaluate the performance of the proposed system and method, we rapidly and accurately located the regions of interest in 3D tissue culture models, such as tumor spheroids and microvascular bed, and instantaneously acquired volumetric high-resolution fluorescence images. We also used an integrated system to monitor tumor spheroids mixed with extracellular matrix (ECM) over five days of the culture process, and the FM–OCM integrated technique successfully imaged the overall 3D structures, such as the distribution and boundaries of the spheroids and ECM as well as stained tumor cells. This complementary information is useful for understanding the relationship between cellular behaviors, such as the proliferation and migration of tumor cells, and microenvironments, such as the ECM.

Permittivity tensor imaging: modular label-free imaging of 3D dry mass and 3D orientation at high resolution

The dry mass and the orientation of biomolecules can be imaged without a label by measuring their permittivity tensor (PT), which describes how biomolecules affect the phase and polarization of light. Three-dimensional (3D) imaging of PT has been challenging. We present a label-free computational microscopy technique, PT imaging (PTI), for the 3D measurement of PT. PTI encodes the invisible PT into images using oblique illumination, polarization-sensitive detection and volumetric sampling. PT is decoded from the data with a vectorial imaging model and a multi-channel inverse algorithm, assuming uniaxial symmetry in each voxel. We demonstrate high-resolution imaging of PT of isotropic beads, anisotropic glass targets, mouse brain tissue, infected cells and histology slides. PTI outperforms previous label-free imaging techniques such as vector tomography, ptychography and light-field imaging in resolving the 3D orientation and symmetry of organelles, cells and tissue. We provide open-source software and modular hardware to enable the adoption of the method.

Effects of Speleotherapy on Aerobiota: A Case Study from the Sežana Hospital Cave, Slovenia

Speleotherapy is one of the non-pharmacological methods for the treatment and rehabilitation of patients with chronic respiratory diseases, especially those with chronic obstructive pulmonary disease (COPD) and asthma. On the one hand, one of the alleged main advantages of speleotherapeutic caves is the low microbial load in the air and the absence of other aeroallergens, but on the other hand, due to the lack of comprehensive air monitoring, there is little information on the pristine and human-influenced aerobiota in such environments. The aim of this study was to assess the anthropogenic effects of speleotherapy on the air microbiota and to investigate its potential impact on human health in Sežana Hospital Cave (Slovenia). From May 2020 to January 2023, air samples were collected in the cave before and after speleotherapeutic activities using two different volumetric air sampling methods—impaction and impingement—to isolate airborne microbiota. Along with sampling, environmental data were measured (CO2, humidity, wind, and temperature) to explore the anthropogenic effects on the aerobiota. While the presence of patients increased microbial concentrations by at least 83.3%, other parameters exhibited a lower impact or were attributed to seasonal changes. The structure and dynamics of the airborne microbiota are similar to those in show caves, indicating anthropization of the cave. Locally, concentrations of culturable microorganisms above 1000 CFU/m3 were detected, which could have negative or unpredictable effects on the autochthonous microbiota and possibly on human health. A mixture of bacteria and fungi typically associated with human microbiota was found in the air and identified by MALDI-TOF MS with a 90.9% identification success rate. Micrococcus luteus, Kocuria rosea, Staphylococcus hominis, and Staphylococcus capitis were identified as reliable indicators of cave anthropization.

Proteome profiling of home-sampled dried blood spots reveals proteins of SARS-CoV-2 infections

BackgroundSelf-sampling of dried blood spots (DBS) offers new routes to gather valuable health-related information from the general population. Yet, the utility of using deep proteome profiling from home-sampled DBS to obtain clinically relevant insights about SARS-CoV-2 infections remains largely unexplored.MethodsOur study involved 228 individuals from the general Swedish population who used a volumetric DBS sampling device and completed questionnaires at home during spring 2020 and summer 2021. Using multi-analyte COVID-19 serology, we stratified the donors by their response phenotypes, divided them into three study sets, and analyzed 276 proteins by proximity extension assays (PEA). After normalizing the data to account for variances in layman-collected samples, we investigated the association of DBS proteomes with serology and self-reported information.ResultsOur three studies display highly consistent variance of protein levels and share associations of proteins with sex (e.g., MMP3) and age (e.g., GDF-15). Studying seropositive (IgG+) and seronegative (IgG-) donors from the first pandemic wave reveals a network of proteins reflecting immunity, inflammation, coagulation, and stress response. A comparison of the early-infection phase (IgM+IgG-) with the post-infection phase (IgM-IgG+) indicates several proteins from the respiratory system. In DBS from the later pandemic wave, we find that levels of a virus receptor on B-cells differ between seropositive (IgG+) and seronegative (IgG-) donors.ConclusionsProteome analysis of volumetric self-sampled DBS facilitates precise analysis of clinically relevant proteins, including those secreted into the circulation or found on blood cells, augmenting previous COVID-19 reports with clinical blood collections. Our population surveys support the usefulness of DBS, underscoring the role of timing the sample collection to complement clinical and precision health monitoring initiatives.

Mueller-Gabor holographic microscopy

Despite the emergence of various methods for Mueller matrix recovery, achieving complete volumetric Mueller matrix retrieval remains a challenge. An alternative approach that leverages in-line Gabor holography to comprehensively extract polarization information from volumetric samples is introduced in this context. The proposed polarization-sensitive in-line Gabor holographic setup enables the recovery of the complete Mueller matrix of three-dimensional (3D) samples after the numerical repropagation of the holographically rendered complex field to various sample planes. This proposal is validated using a calibrated birefringent polarization test target, a sample of Calcium Oxalate crystals, and a volumetric sample containing microplastics, providing the 3D measurement of polarimetric parameters such as diattenuation, polarizance, depolarization, and retardance. The results agree with those obtained through reference methods based on image-plane brightfield polarimetry. The in-line Gabor holographic system proposed is sensitive to the axial variations in polarimetric information within volumetric samples without any mechanical movement nor optical adjustments— an accomplishment that remains elusive to conventional image-plane reference methods and non-holographic/interferometric systems. These findings emphasize the versatility and potential of this alternative approach in recovering the intricate polarization characteristics of 3D specimens, offering the first in-line holographic Mueller imaging to the best of the authors' knowledge.

Investigation of thermoelectric properties of nanocrystalline copper chalcogenides

Modern research efforts are aimed at developing fuel cells characterized by high efficiency, low cost and environmental friendliness, which largely depend on the properties of the corresponding catalyst materials ― the most important components of the fuel cell. Catalysts based on metal chalcogenides, predominantly S based, have activity in accelerating the oxygen reduction reaction comparable to the activity of Pt in H2SO4. The work uses the technique of compacting powder materials and obtained volumetric samples. Nanodisperse powder fractions with an average particle size of (50–100) nm were obtained. The values of the thermo-emf coefficient (about 0.08 mV/K) were obtained for the studied alloy with low defects in the cation sublattice of the Сu2S0.5Te0.5 type. It was found that a decrease in grain size leads to a significant decrease in electronic conductivity for all studied samples. The paper presents the results of a study of the thermoelectric properties of the Cu2S0.5Te0.5 triple alloy. For the studied composition, a decrease in thermal conductivity by (25‒30)% and a slight increase in the thermal emf coefficient compared with large–crystal samples were obtained. Low thermal conductivity was found in the range (0.3–1.1) W m-1 K-1 with a conductivity above 1000 ohms-1cm-1. For the studied sample Cu2S0.5Te0.5 ― thermoelectric efficiency (ZT = 0.25) at 400 °C, which allows us to hope for the possibility of improving the characteristics of samples of this composition to acceptable values for practical thermoelectric devices by selecting the optimal alloying.

Relative and absolute difference in soil organic carbon stocks in grassland soils in Ireland: Impact of rock fragments, bulk density and calculation methods

On-farm management measures can sequester carbon by removing carbon dioxide from the atmosphere and storing it securely for long periods, in our soils. Estimates of soil organic carbon (SOC) stocks differ by calculation methods in terms of how they account for the coarse >2 mm fraction (i.e. rock fragments) of the soil. Irish grassland soils have variable volumetric stone contents and the extent of overestimation is unknown. Without best practice guidance, calculations of SOC in these soils are vulnerable to overestimation. The objectives of the present study for grassland soils in Ireland were to: 1) calculate mean SOC stocks using different methods by soil horizon and volumetric stone content class; 2) highlight relative differences in SOC stocks between these calculation methods and 3) compare normalised layer (Ly, fixed depth) versus horizon (Hz) type derived sampling data in terms of SOC stocks, to establish a best practice standardised sampling protocol. Five methods (M, 1–3 overestimate SOC stocks, whereas 4–5 are equivalent and are closest to reality) to calculate SOC stocks were used in combination with three soil databases i.e. Irish Soil Information System (I-SIS), the Heavy Soils Programme (HSP) and the Soil Quality Assessment Research Project (SQUARE). Objectives 1 and 2 were assessed using all three databases across methods, whereas objective 3 used the SQUARE database and M4. These data were sorted into volumetric stone content (%) classes (< 5%, 5–10%, 10–20%, 20–30% and > 30%) and sampling horizon (O, A, E, A/B, B, B/C, and C) with SOC stocks calculated using M1–5 equations. Results confirmed the high volumetric stone content assumption of grassland soils in Ireland (exception O horizons). Volumetric stone contents ranged from 0% to 36% for all horizons. When M1–5 are considered the average relative difference in SOC stocks between M1 and M5 was 18.9% (max: 388%), M2 and M5 was 7.7% (max: 60.7%) and M3 and M5 was 8.9 (max: 310%). In terms of Ly versus Hz sampling, no significant differences were found for the A horizons sampled. However, in Ireland, best practice should still utilise elements from both Ly (using an auger to get fixed depth soil samples; analysed for organic C) and Hz (using a soil profile pit to extract representative BD cores and to gather bulk samples for volumetric stone content analysis) approaches in the field. Laboratory methods used must fit with the needs and assumptions of equations M4/5 to calculate SOC stocks (thereby minimising overestimation and indeed underestimation).

A Clinical User Study Investigating the Benefits of Adaptive Volumetric Illumination Sampling.

Accurate and fast understanding of the patient's anatomy is crucial in surgical decision making and particularly important in visceral surgery. Sophisticated visualization techniques such as 3D Volume Rendering can aid the surgeon and potentially lead to a benefit for the patient. Recently, we proposed a novel volume rendering technique called Adaptive Volumetric Illumination Sampling (AVIS) that can generate realistic lighting in real-time, even for high resolution images and volumes but without introducing additional image noise. In order to evaluate this new technique, we conducted a randomized, three-period crossover study comparing AVIS to conventional Direct Volume Rendering (DVR) and Path Tracing (PT). CT datasets from 12 patients were evaluated by 10 visceral surgeons who were either senior physicians or experienced specialists. The time needed for answering clinically relevant questions as well as the correctness of the answers were analyzed for each visualization technique. In addition to that, the perceived workload during these tasks was assessed for each technique, respectively. The results of the study indicate that AVIS has an advantage in terms of both time efficiency and most aspects of the perceived workload, while the average correctness of the given answers was very similar for all three methods. In contrast to that, Path Tracing seems to show particularly high values for mental demand and frustration. We plan to repeat a similar study with a larger participant group to consolidate the results.

Application of Green’s Functions of Stratified Media to Calculate the Radiation Field of Antennas Near a Reflecting Surface

We are examining a method of calculating the electromagnetic field emitted by an aperture antenna near a reflecting boundary using the Huygens element model. We utilize the Green’s tensor functions to calculate the electromagnetic field, considering the inhomogeneous structure of the medium under the boundary and taking into account electric and magnetic currents as a source. Unlike standard electromagnetic modeling, programmes that require determination of the field components in the entire area, our approach allows calculating the distribution of amplitude and phase of all field components only in the desired area. We also consider the parameters of the layered medium under the reflecting boundary in recording the characteristic parts of the Green’s functions, leading to multiple gains in computing resources. Our method and the ANSYS HFSS programme are used to calculate the electromagnetic field patterns. We found that using a volumetric sampling grid in the ANSYS HFSS programme leads to phantom defects in the field structure and its asymmetry, even with a symmetrical position of the sources. We present field patterns for both the Huygens element and the open end of a rectangular waveguide for different types of reflecting boundary. We assert the validity and physical plausibility of the obtained solutions. We also consider the change in the reflection coefficient from the boundary, taking into account the curvature of the phase in front of the radiator in the near zone. This proposed model can be used to develop domestic software for electromagnetic modeling.

QUICK PROTOCOL FOR INTEGRATING THE ATTRIBUTE INFORMATION OF UNSTRUCTURED POINT CLOUD DATA INTO A SOLAR ENVELOPE SIMULATION

ABSTRACT This study proposes a novel method of solar geometry by considering the potential application of point cloud data combined with the simulation of solar radiation. With the support of geometric and radiometric information stored in the point cloud such as position information (XYZ) color information (RGB), and reflection intensity (I), architects may compensate for missing information on the existing context during the simulation, especially due to the limited capacity of current 3D modelling sites. However, the dataset often comes in the format of unstructured point cloud data retrieved from merged data scans and as a result, the radiometric information is difficult to occupy due to multiple reference points. Through a 3D subtractive procedure, this study not only examines volumetric samples of the three-dimensional matrix that fulfills the criteria of solar envelopes but also finds the optimal values of the merged data scan for input of solar radiation. In this regard, simulation of solar radiation contributes to identifying the most and the least exposed areas to the sun in existing contexts. This provides information related to visible sun hours that can be used to perform ray tracing analysis between the proposed 3D plot and surrounding contexts. Our proposed method ultimately helps architects not only generate solar geometry based on real contextual settings but also to understand comprehensively the microclimate conditions of the design context.

Validity of a novel optical coherence tomography angiography flow index in a cohort of primary open angle glaucoma

BackgroundVascular mechanisms are implicated in many ocular diseases. Therefore, different vascular imaging modalities are used in management of such conditions. Optical coherence tomography angiography (OCTA) has high spatial resolution and segmentable 3D volumetric sampling enabling isolation of retinal and peripapillary vascular beds. However, OCTA only indirectly derives quantitative flow data i.e. velocimetry through methods and algorithms liable to limitations like signal saturation. This study introduces and validates novel mathematical OCTA flow indices that may compensate for some OCTA velocimetric limitations.MethodsThirty-seven eyes of 23 POAG patients were included. Each underwent baseline and follow-up assessment one month thereafter. Assessment comprised full ophthalmological examination, intraocular pressure (IOP), systemic arterial blood pressure (SABP) and OCTA macula and ONH. Angiograms were processed using ImageJ to calculate OCTA intensity-based flow indices (FIOs), for superficial vascular plexus (SVP), deep vascular plexus (DVP) and optic nerve head vascular plexus (ONH-RPC), i.e. SFIO, DFIO and ONHFIO respectively. Mean ocular perfusion pressure (MOPP) was calculated using IOP and SABP. OCTA vascular densities (VD) and MOPP were used to calculate three respective mathematical flow indices (FIMs) for SVP, DVP and ONH-RPC, based on Hagen-Poiseuille law, i.e. SFIM, DFIM, ONHFIM respectively. Pearson test was used for correlation between the two sets of indices. Intraclass correlation coefficient (ICC) was tested for baseline and follow-up values for each index.ResultsThere was positive correlation between the three FIMs and their respective FIOs at baseline and follow-up ranging between high and moderate. Correlation coefficients (CCs) were 0.773 and 0.609 for SFIM and SFIO P-value < 0.001, 0.829 and 0.624 for DFIM and DFIO P-value < 0.001 and 0.516 and 0.737 for ONHFIM P-value = 0.001 for baseline and follow-up respectively. ICCs were 0.772 P-value < 0.001, 0.328 P-value = 0.022 and 0.888 P-value < 0.001 for SFIM, DFIM and ONHFIM respectively. For SFIO, DFIO and ONHFIO, ICCs were 0.420 P-value = 0.004, 0.079 P-value = 0.320 and 0.833 P-value < 0.001 respectively.ConclusionThe novel FIMs are reliable alternatives to FIOs and may compensate for OCTA signal saturation in extremes of MOPP. SFIM and ONHFIM showed high ICCs with excellent reliability. While DFIM demonstrated low ICC indicating poor reliability, it still performed better than its corresponding DFIO.

Clinical performance of volumetric finger-prick sampling for the monitoring of tacrolimus, creatinine and haemoglobin in kidney transplant recipients.

Finger-prick sampling has emerged as an attractive tool for therapeutic drug monitoring and associated diagnostics. We aimed to validate the clinical performance of using two volumetric devices (Capitainer® qDBS and Mitra®) for monitoring tacrolimus, creatinine and haemoglobin in kidney transplant (KTx) recipients. Secondarily, we evaluated potential differences between finger-prick sampling performed by healthcare professionals vs. self-sampling, and differences between the two devices. We compared finger-prick and venous sampling in three settings: microsampling performed by healthcare personnel, self-sampling under supervision, unsupervised self-sampling. The finger-prick samples were analysed with adapted methods and results compared to routine method analysis of the venous blood samples. Twenty-five KTx recipients completed the main study and 12 KTx recipients completed a post hoc validation study. For tacrolimus measurements and predicted area under the curve, the proportions within ±20% difference were 79%-96% for Capitainer and 77%-95% for Mitra. For creatinine and haemoglobin, the proportions within ±15% were 92%-100% and 93%-100% for Capitainer and 79%-96% and 67%-92% for Mitra, respectively. Comparing sampling situations, the success rate was consistent for Capitainer (92%-96%), whereas Mitra showed 72%-88% and 52%-72% success rates with samples collected by healthcare personnel and the patients themselves. Capitainer and Mitra are technically feasible for measuring tacrolimus, creatinine and haemoglobin. In the context of self-sampling, Capitainer maintained consistent sampling success and analytical quality. Implementing volumetric finger-prick self-sampling for the monitoring of tacrolimus, creatinine and haemoglobin may simplify and improve the follow-up of KTx recipients.

A Survey of Airborne Fungi and Their Sensitization Profile in Wuhan, China

Introduction: Airborne fungi induce allergic symptoms in 3–10% of the population worldwide. To better prevent and manage fungi-related allergic diseases, it is essential to identify the genus and the distribution profile of airborne fungi. Methods: With this purpose in mind, we carried out a 12-month volumetric sampling study to monitor the airborne fungi and retrospectively analyzed the sensitization profile of four dominant fungi (Cladosporium, Alternaria, Aspergillus, and Penicillium) among respiratory allergies during the same study period in Wuhan, China. Results: A total of 29 different fungal genuses were identified, and the peak fungal concentration period was found to be in September and October, followed by May and June. The most prevalent fungi in this area were Cladosporium (36.36%), Ustilago (20.12%), and Alternaria (13.87%). In addition, the skin prick test data from 1,365 respiratory allergies patients showed that 202 (14.80%) of them were sensitized to fungi. The sensitization rates to Cladosporium, Alternaria, Aspergillus, and Penicillium were 11.72%, 4.69%, 1.98%, and 4.76%, respectively. The seasonal fluctuation of Alternaria and Aspergillus correlated with their sensitization rates. Among the fungal sensitized patients, 76 (37.62%) were sensitized to two or more kinds of fungi. The serum-specific IgE tests suggested low to high correlations existed between these fungi; however, these correlations were not found between fungi and other allergens. Conclusion: Our study provides the distribution profile and reveals the clinical significance of the airborne fungi in Wuhan, which will facilitate the precise management of fungal allergy.

Temporal variation in the spectrum and concentration of airborne microalgae and cyanobacteria in the urban environments of inland temperate climate.

Despite their non-negligible representation among the airborne bioparticles and known allergenicity, autotrophic microorganisms-microalgae and cyanobacteria-are not commonly reported or studied by aerobiological monitoring stations due to the challenging identification in their desiccated and fragmented state. Using a gravimetric method with open plates at the same time as Hirst-type volumetric bioparticle sampler, we were able to cultivate the autotrophic microorganisms and use it as a reference for correct retrospective identification of the microalgae and cyanobacteria captured by the volumetric trap. Only in this way, reliable data on their presence in the air of a given area can be obtained and analysed with regard to their temporal variation and environmental factors. We gained these data for an inland temperate region over 3 years (2018, 2020-2021), identifying the microalgal genera Bracteacoccus, Desmococcus, Geminella, Chlorella, Klebsormidium, and Stichococcus (Chlorophyta) and cyanobacterium Nostoc in the volumetric trap samples and three more in the cultivated samples. The mean annual concentration recorded over 3 years was 19,182 cells*day/m3, with the greatest contribution from the genus Bracteacoccus (57%). Unlike some other bioparticles like pollen grains, autotrophic microorganisms were present in the samples over the course of the whole year, with greatest abundance in February and April. The peak daily concentration reached the highest value (1011 cells/m3) in 2021, while the mean daily concentration during the three analysed years was 56 cells/m3. The analysis of intra-diurnal patterns showed their increased presence in daylight hours, with a peak between 2 and 4 p.m. for most genera, which is especially important due to their potential to trigger allergy symptoms. From the environmental factors, wind speed had a most significant positive association with their concentration, while relative air humidity had a negative influence.

Determination of detection efficiency on HPGe detector for point-like and volumetric samples based on Geant4 simulations

Production of medical isotopes has recently been developed at the Institute of Modern Physics (IMP) in China and many aqueous samples containing produced radioisotopes at wide range of volume were generated. Evaluation of radionuclidic purity and quantification of radioactivity for these samples are of significant importance, especially for medical purpose. High purity germanium (HPGe) detectors and gamma spectrometry are widely used in radionuclidic purity evaluation due to the high energy resolution. However, radionuclidic purity assessment and determination of radioactivity cannot be accurately conducted by using the HPGe detector installed at Laboratory of Nuclear Chemistry in IMP due to the lack of competent calibration standard sources. Therefore, an efficient method based on Geant4 simulation was proposed to calculate the detection efficiency curve for samples with different geometry, composition and source-to-detector distance. A set of efficiency data measured with a point-like standard source containing multi-radionuclides was used to determine the dimension of germanium crystal and thickness of dead layers. Afterwards, a point-like and 3 volumetric standard sources (5 ml, 10 ml and 20 ml, respectively) containing 152Eu were measured at 5–50 cm source-to-detector distances. The EFFTRAN code was applied to calculate the correction factor of coincidence summing for all measurements. The full energy peak (FEP) efficiencies with energy range of 121–1408 keV were calculated and compared with the values obtained from simulations. The simulated FEP efficiency values were in good agreement with experimental results, which illustrated a satisfactory precision of the Geant4 simulations. The feasibility of obtaining detection efficiency for point-like and volumetric samples by means of Geant4 simulations was confirmed. This method can be applied to address the efficiency problem caused by sample geometry and composition.

THE INFLUENCE OF THE MAIN PARAMETERS OF THE SLM PROCESS ON THE DENSITY OF VOLUME PARTS

THE INFLUENCE OF THE MAIN PARAMETERS OF THE SLM PROCESS ON THE DENSITY OF VOLUME PARTS