Diameter Range Research Articles

Three-dimensional clustering characteristics of large-Stokes-number dilute sprays interacting with turbulent swirling co-flows

Three-dimensional (3-D) clustering characteristics of large-Stokes-number sprays interacting with turbulent swirling co-flows are investigated experimentally. The astigmatic interferometric particle imaging (AIPI) technique is used for simultaneous measurement of the spray droplets position in 3-D space and their corresponding diameter. The Stokes number estimated based on the Kolmogorov time scale varies from 34 to 142. The results show that the degree of droplet clustering plateaus at about 0.4 and at large Stokes numbers. It is obtained that the mean length scale of the clusters normalized by the Kolmogorov length scale follows a power-law relation, and the mean void length scale normalized by the integral length scale plateaus at about 1.5 and at large Stokes numbers. It is shown that the ratio of the number density of the droplets residing within the clusters to the global number density increases with increasing Stokes number and is about 8 for the largest Stokes number examined in this study. The joint characteristics of cluster's normalized volume and the mean diameter of droplets residing within the clusters show that small-volume clusters accommodate droplets with a relatively broad range of diameters. However, large clusters carry droplets with the most probable diameter. The developed AIPI technique in the present study and the corresponding spray characteristics are of importance for engineering applications that aim to understand the 3-D clustering characteristics of large-Stokes-number droplets sprayed into turbulent swirling co-flows.

Analysis and Experimental Study on the Influence of Louver Separation Device on the Sand Collection Efficiency of Wind Erosion Instrument

A wind erosion instrument is a core instrument for collecting sand particles in wind and sand flows and studying the laws of wind and sand movement. To study the influence of the internal structure of the wind erosion instrument on its sand collection efficiency, a built-in louver separation device was designed. Based on CFD and Fluent 2022 software, numerical analysis was conducted using an RNG k-ε model, and the discrete phase model (DPM) method was used to calculate the sand collection efficiency. The flow field analysis of the new wind–sand separator was carried out. The influence of blade inclination angle, blade thickness, and blade number on sand collection efficiency was studied using single-factor and response surface analysis methods. The optimal parameter combination was obtained as blade inclination angle of 30°, blade thickness of 1.25 mm, and blade number of 10. A simulation model was established based on the optimal combination parameters, and the performance of the wind erosion instrument before and after the addition of the louver separation device was compared. The simulation results show that adding a louver separation device can increase static pressure, alleviate short-circuit flow and back-mixing phenomena, and stabilize the flow field; increasing tangential velocity leads to an increase in particle centrifugal force; reduce axial velocity, prolong particle stagnation time, and minimize particle escape. The particle trajectory pattern is mostly a continuous spiral path, which is conducive to capturing particles and improving sand collection efficiency. Compared with the original structure, for particles with diameters ranging from 0.001–0.05 mm, 0.005–0.01 mm, 0.01–0.05 mm, 0.05–0.1 mm, and 0.1–0.5 mm, the addition of a louver separation device increased the sand collection efficiency by 32.74%, 22.55%, 33.17%, 11.45%, and 0.13%, respectively. When the wind speed is 13.8 m/s and the diameter range is 0.001–0.5 mm, the average sand collection efficiency obtained from simulation tests and wind tunnel tests is 86.18% and 84.32%, respectively, with an error of 2.2%. The simulation results are reliable. The research results show that adding a louver separation device can improve the sand collection efficiency of the wind erosion instrument, and has better overall performance compared to the original wind–sand separator. This study provides a basis for further research on the structure of wind erosion gauges and the environmental protection of farmland. Strengthening land management can effectively protect soil resources, reduce wind erosion, ensure the stability of the ecosystem, and lay the foundation for promoting the sustainable use of land.

Corrosion and wear performance and mechanism study of ZrB2/AA6016

Abstract This study involved the fabrication of aluminum matrix composites reinforced with ZrB2/AA6016 particles using the KBF4-Al-K2ZrF6 reaction system， the composites were then subjected to T6 heat treatment. An investigation was conducted to examine the impact of varying friction speeds on the corrosion and wear characteristics of ZrB2/AA6016. An investigation was conducted to study the frictional wear behavior of ZrB2/AA6016 in the presence of 3.5wt. % NaCl, both before and after T6 heat treatment. The study also aimed to understand the underlying mechanism of this behavior. The results indicate that the T6 heat treatment mitigates the impact of thermal stresses and strains caused by thermal mismatch, hence enhancing the material's wear resistance. The coefficient of friction (COF) for heat-treated ZrB2/AA6016 is lower than that for unheated-treated ZrB2/AA6016. As friction increases, the pace at which the material wears down tends to decrease. At a friction wear velocity of 50 mm/s, the wear rate of the material is minimized both before and after heat treatment, measuring 0.23×10-2mm3/Nm and 0.22×10-2mm3/Nm, respectively. Through the utilization of XRD, SEM, EBSD, TEM, and XPS analytical techniques, it has been determined that the ZrB2 particles exhibit strong bonding with the Al matrix. Additionally, the particle diameters range from 50~150nm. Following the T6 heat treatment, the grain size measured 40.53μm, while the proportion of large-angle grain boundaries was found to be 66.4%. The accumulation of Cl- resulted in the formation of localized corrosion pits on the surface undergoing wear, hence hastening the deterioration of the material. The primary causes of wear failure are corrosive wear, abrasive wear, and oxidative wear.

Formulation, characterization and evaluation of minocycline hydrochloride loaded polyurethane/collagen nanofibers via electrospinning as wound dressings

Objective It was aimed to formulate minocyline. HCI loaded electrospun polyurethane/collagen (PU/Col) and polyurethane/collagen/polycaprolactone (PU/Col/PCL) nanofibers are intended for use as a wound dressing. Methods The effect of polymer ratio and addition of PCL on the morphology, diameter, drug delivery, encapsulation efficiency, mechanical properties, antibacterial activity against Escherichia coli and Staphylococcus aureus, cytotoxicity, cell adhesion and proliferation were investigated. 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to test the cytotoxicity of the nanofibers on the human dermal fibroblast (HDF) cell line. Cell proliferation/adhesion was also determined by imaging HDF cells seeded on mats with scanning electron microscopy/fluorescence microscopy. Results All nanofibers were bead-free and smooth in the diameter range of 866.7–882.4 nm. They had favorable encapsulation efficiency (≥79.3%), controlled drug release up to 24 h and did not have cytotoxic effects. Although collagen was preferred for cell adhesion and proliferation, its spinnability and mechanical properties were poor. While PU improved the spinnability of collagen, its mechanical properties also enhanced with the addition of PCL. Nevertheless, all mats led to favorable cell adhesion and proliferation. All the nanofibers had antimicrobial activity against Escherichia coli and Staphylococcus aureus. Conclusion In conclusion, PU/Col and PU/Col/PCL nanofiber mats, which had favorable encapsulation efficiency, controlled drug release and antibacterial activity at least 24 h, cell viability, proliferation, adhesion, mechanical properties to be used as wound dressing, were successfully prepared.

AAV1.tMCK.NT-3 gene therapy improves phenotype in Sh3tc2-/- mouse model of Charcot-Marie-Tooth Type 4C.

Charcot-Marie-Tooth Type 4C (CMT4C) is associated with mutations in the SH3 domain and tetratricopeptide repeats 2 (SH3TC2) gene, primarily expressed in Schwann cells (SCs). Neurotrophin-3 (NT-3) is an important autocrine factor for SC survival and differentiation, and it stimulates neurite outgrowth and myelination. In this study, scAAV1.tMCK.NT-3 was delivered intramuscularly to 4-week-old Sh3tc2-/- mice, a model for CMT4C, and treatment efficacy was assessed at 6-month post-gene delivery. Efficient transgene production was verified with the detection of NT-3 in serum from the treated cohort. NT-3 gene therapy improved functional and electrophysiological outcomes including rotarod, grip strength and nerve conduction velocity. Qualitative and quantitative histopathological studies showed that hypomyelination of peripheral nerves and denervated status of neuromuscular junctions at lumbrical muscles were also improved in the NT-3-treated mice. Morphometric analysis in mid-sciatic and tibial nerves showed treatment-induced distally prominent regenerative activity in the nerve and an increase in the estimated SC density. This indicates that SC proliferation and differentiation, including the promyelination stage, are normal in the Sh3tc2-/- mice, consistent with the previous findings that Sh3tc2 is not involved in the early stages of myelination. Moreover, in size distribution histograms, the number of myelinated axons within the 3- to 6-µm diameter range increased, suggesting that treatment resulted in continuous radial growth of regenerating axons over time. In conclusion, this study demonstrates the efficacy of AAV1.NT-3 gene therapy in the Sh3tc2-/- mouse model of CMT4C, the most common recessively inherited demyelinating CMT subtype.

Mechanical confinement matters: Unveiling the effect of two-photon polymerized 2.5D and 3D microarchitectures on neuronal YAP expression and neurite outgrowth

The effect of mechanical cues on cellular behaviour has been reported in multiple studies so far, and a specific aspect of interest is the role of mechanotransductive proteins in neuronal development. Among these, yes-associated protein (YAP) is responsible for multiple functions in neuronal development such as neuronal progenitor cells migration and differentiation while myocardin-related transcription factor A (MRTFA) facilitates neurite outgrowth and axonal pathfinding. Both proteins have indirectly intertwined fates via their signalling pathways. There is little literature investigating the roles of YAP and MRTFA in vitro concerning neurite outgrowth in mechanically confined microenvironments. Moreover, our understanding of their relationship in immature neurons cultured within engineered confined microenvironments is still lacking. In this study, we fabricated, via two-photon polymerization (2PP), 2.5D microgrooves and 3D polymeric microchannels, with a diameter range from 5 to 30 μm. We cultured SH-SY5Y cells and differentiated them into immature neuron-like cells on both 2.5D and 3D microstructures to investigate the effect of mechanical confinement on cell morphology and protein expression. In 2.5D microgrooves, both YAP and MRTFA nuclear/cytoplasmic (N/C) ratios exhibited maxima in the 10 μm grooves indicating a strong relation with mechanical-stress-inducing confinement. In 3D microchannels, both proteins’ N/C ratio exhibited minima in presence of 5 or 10 μm channels, a behaviour that was opposite to the ones observed in the 2.5D microgrooves and that indicates how the geometry and mechanical confinement of 3D microenvironments are unique compared to 2.5D ones due to focal adhesion, actin, and nuclear polarization. Further, especially in presence of 2.5D microgrooves, cells featured an inversely proportional relationship between YAP N/C ratio and the average neurite length. Finally, we also cultured human induced pluripotent stem cells (hiPSCs) and differentiated them into cortical neurons on the microstructures for up to 2 weeks. Interestingly, YAP and MRTFA N/C ratios also showed a maximum around the 10 μm 2.5D microgrooves, indicating the physiological relevance of our study. Our results elucidate the possible differences induced by 2.5D and 3D confining microenvironments in neuronal development and paves the way for understanding the intricate interplay between mechanotransductive proteins and their effect on neural cell fate within engineered cell microenvironments.

Vertical Variability in morphology, chemistry and optical properties of the transported Saharan air layer measured from Cape Verde and the Caribbean.

The structural properties of the Saharan air layer (SAL) including chemical, morphological and optical properties were measured during the Saharan Aerosol Longrange TRansport and Aerosol Cloud interaction Experiment (SALTRACE- June/July 2013). Flight measurements were done from Cape Verde and the Caribbean. Changes happening with the chemical composition, mixing, shape and absorption of aerosol single particles (particle diameter range 0.5-3.0 µm) inside SAL during its transport are detailed. Dust-dominated SAL (relative number abundance >90%) and generally low mixing (<1% with sea-salt and sulphates) are observed at both locations. The change in shape (determined as aspect ratio (AR)) after transatlantic transport was statistically not significant. The iron oxide fraction, important for light absorption, contributed 6.0-6.8% to SAL dust. A lower amount of Fe oxides was observed in transported SAL, especially for the size range 0.5-1.5 µm. This reduction in Fe oxide content resulted in a 4% decrease (0.0046-0.0044) in dust imaginary refractive index and a 1% decrease in single scattering albedo (0.802-0.809) at 520 nm. Our work suggests including the size distribution of iron oxides and their particular behaviour in future experiment/model studies.

Visualizing nuclear pore complex plasticity with Pan-Expansion Microscopy.

Cell-type specific and environmentally-responsive plasticity in nuclear pore complex (NPC) composition and structure is an emerging area of investigation, but its molecular underpinnings remain ill defined. To understand the cause and consequence of NPC plasticity requires technologies to visualize differences within individual NPCs across the thousands in a given nucleus. We evaluate the utility of Pan Expansion Microscopy (Pan-ExM), which enables 16-20 fold isotropic cell enlargement while preserving the proteome, to reveal NPC plasticity. NPCs are robustly identified by deep learning-facilitated segmentation as tripartite structures corresponding to the nucleoplasmic ring, inner ring with central transport channel, and cytoplasmic ring, as confirmed by immunostaining. We demonstrate a range of NPC diameters with a bias for dilated NPCs at the basal nuclear surface, often in local clusters. These diameter biases are eliminated by disrupting linker of nucleoskeleton and cytoskeleton (LINC) complex-dependent connections between the nuclear envelope (NE) and the cytoskeleton, supporting that they reflect local variations in NE tension. Pan-ExM further reveals that the transmembrane nucleoporin/nup POM121 resides specifically at the nuclear ring in multiple model cell lines, surprising given the expectation that it would be a component of the inner ring like other transmembrane nups. Remarkably, however, POM121 shifts from the nuclear ring to the inner ring specifically in aged induced pluripotent stem cell derived neurons (iPSNs) from a patient with C9orf72 amyotrophic lateral sclerosis (ALS). Thus, Pan-ExM allows the visualization of changes in NPC architecture that may underlie early steps in an ALS pathomechanism. Taken together, Pan-ExM is a powerful and accessible tool to visualize NPC plasticity in physiological and pathological contexts at single NPC resolution.

Considerations for method development and method translation in capillary liquid chromatography: A tutorial

HPLC remains one of the most widely used measurement techniques for chemical analysis. Capillary LC, which utilizes narrow diameter columns operated at lower flow rates than analytical-scale LC, continues to gain adoption based on its reduced mobile phase consumption and increased sensitivity when coupled to MS detection. This tutorial offers practical insights into the most critical aspects of translating analytical-scale separations to the capillary scale. The selection of pumping systems, detectors, and the potential for performance loss due to extra-column effects are examined within the context of separations using columns with inner diameters ≤ 0.3 mm. Column choices within this diameter range are also detailed, both in terms of stationary phase support options and general commercial availability. The impact of these various factors on the effective development/translation of LC methods down to flow rates under 10 µL/min is described to provide readers with a basis for implementing these strategies within their own analytical workflows.

Differences in left atrial stain, endothelial glycocalyx, arterial elasticity and myocardial efficiency between ESUS, lacunar, cardioembolic and atherosclerotic type of stroke

Abstract Background Patients with stroke are at greater risk of developing cardiovascular complications. Purpose We addressed endothelial glycocalyx, arterial stiffness, left atrial and ventricular function in patients with lacunar, atherosclerotic, cardioembolic and stroke of undetermined source (ESUS). Methods We recruited 194 patients (aged 58.8± 10.8 years old) with acute cerebral stroke (47 lacunar, 50 atherosclerotic,48 ESUS and 49 cardioembolic) and 50 controls with similar risk factors and 40 controls with similar profile regarding common risk factors (diabetes, hypertension, hyperlipidemia, coronary artery disease, smoking; p&amp;gt;0.05 for all comparisons). We measured: (1) perfused boundary region (PBR) of the sublingual microvessels (diameter range 5–25 μm), a marker inversely related with glycocalyx thickness, (2) pulse wave velocity carotid-to-femoral (PWV), central systolic blood pressure (cSBP), and central diastolic blood pressure (cDBP), (3) Left atrial (LA) strain using speckle-tracking imaging, (4) left ventricular global longitudinal strain and (5) left ventricular myocardial work index (GWI), constructive work (GCW), wasted work (GWW) and work efficiency (GWE), (6) ventriculoarterial coupling, expressed by the ratio PWV/GLS. Results Compared with controls, patients with stroke had higher PWV (11.98±3.21 vs 9.61±1.28 m/sec, p=0.001), PBR (2.20±0.31 vs 1.94±0.20, p=0.019) and central SBP (137.41±24.83 vs 121.15±17.46 mmHg, p=0.018), while LV ventricular (-16.44±4.70 vs -20.89±2.45%, p=0.001) and atrial deformation (26.81±9.32 vs 37.05±5.08%, p&amp;lt;0.001) were more impaired in patients with stroke (p &amp;lt; 0.05). Patients with ESUS had more impaired LA reservoir strain and contraction strain compared to the other 2 stroke types (ESUS 22.9±8.72%, -13.90±4.96%, Lacunar 29.71±10.52%, -16.11±6.10%, atherosclerotic 26.78±10.14%, -13.74±5.65%, p&amp;lt;0.05). Also, patients with ESUS demonstrated better PBR compared to the lacunar and atherosclerotic types (ESUS 2.10±0.27 μm, Lacunar 2.26±0.29 μm, atherosclerotic 2.19±0.29μm, p&amp;lt;0.05). Patients with atherosclerotic stroke had higher PWV compared with other stroke types (Atherosclerotic: 13.59±3.87 m/sec, Lacunar: 11.41±2.35 m/sec, Cardioembolic: 10.66±3.28 m/sec, ESUS: 11.72±2.67 m/sec). Also, patients with atherosclerotic stroke demonstrated the worst PWV/GLS ratio (Atherosclerotic: -0.97±0.35, Lacunar: -0.69±0.25, Cardioembolic: -0.76±0.21, ESUS: -0.70±0.28). Patients with cardioembolic stroke showed similar trend with ESUS, as far LA strain is considered. Conclusion Patients with stroke have impaired atrial strain, endothelial glycocalyx and arterial stiffness, compared with controls. Arterial stiffness and ventriculoarterial coupling are more affected in atherosclerotic strokes. LA strain is more impaired in the ESUS and cardioembolic stroke albeit that endocalyx, though abnormal,is less impaired in these stroke types.

Interobserver variability of clinical target volume delineation in patients undergoing breast-conserving surgery without surgical clips: a pilot study on preoperative magnetic resonance simulation

BackgroundIn patients undergoing breast-conserving therapy without surgical clip implantation, the accuracy of tumor bed identification and the consistency of clinical target volume (CTV) delineation under computed tomography (CT) simulation remain suboptimal. This study aimed to investigate the feasibility of implementing preoperative magnetic resonance (MR) simulation on delineations by assessing interobserver variability (IOV).MethodsPreoperative MR and postoperative CT simulations were performed in patients who underwent breast-conserving surgery with no surgical clips implanted. Custom immobilization pads were used to ensure the same supine position. Three radiation oncologists independently delineated the CTV of tumor bed on the images acquired from MR and CT simulation registration and CT simulation alone. Cavity visualization score (CVS) was assigned to each patient based on the clarity of the tumor bed on CT simulation images. IOV was indicated by generalized conformity index (CIgen), denoted as CIgen−CT and CIgen−MR/CT, and the distance between the centroid of mass (dCOM), denoted as dCOMCT and dCOMMR/CT. The variation of IOV in different CVS subgroups was analyzed.ResultsA total of 10 patients were enrolled in this study. The median and interquartile range (IQR) of maximum pathological diameter of the tumors in all patients were 1.55 (0.80–1.92) cm. No statistical significance was found between the volumes of CTVs on CT simulation and on MR/CT simulation registration images (p = 0.387). CIgen−MR/CT was significantly larger than CIgen−CT (p = 0.005). dCOMMR/CT was significantly smaller than dCOMCT (p = 0.037). The median and IQR of CVS in all patients were 2.34 (2.00–3.08). The difference of CIgen between CIgen−MR/CT and CIgen−CT was larger in the low CVS group (p = 0.016). The difference of dCOM showed a decreasing trend when CVS was lower, although it did not reach statistical significance (p = 0.095).ConclusionsFor patients who underwent breast-conserving surgery without surgical clip implantation, the use of preoperative MR simulation in delineating the CTV of tumor bed decreased the IOV among observers. The consistency of tumor bed identification was improved especially in cases where the margins of tumor bed were challenging to visualize on CT simulation images. The study findings offer potential benefits in reducing local recurrence and minimizing tissue irritation in the surrounding areas. Future investigation in a larger patient cohort to validate our results is warranted.

Self-acceleration effect of Mn/Ce-modified carbide slag in CO2 absorption for CaO/CaCO3 energy storage

Carbide slag, a solid waste from the chlor-alkali industry, can be used for CO2 capture and energy storage. Herein, the cyclic reaction activity of Mn/Ce-modified carbide slag under energy storage conditions was studied. The Mn/Ce-modified carbide slag shows energy storage density over 2100 kJ/kg and CO2 absorption capacity of 0.52 g CO2/g sorbent after 30 cycles. Notably, both carbonation and calcination rates are accelerated with the number of cycles. This self-acceleration effect is related to the evolution of oxygen vacancy concentration and texture structure of Mn/Ce-modified carbide slag during the cycles. In the cycles, CaMnO3 in the Mn/Ce-modified carbide slag reacts with the formed CaCO3 in the carbonation stage to produce more Ca2MnO4. The formation of Ca2MnO4 increases oxygen vacancies in the Mn/Ce-modified carbide slag, significantly enhancing its CO2 absorption capacity. Thus, the release of the increased CO2 in the calcination stage generates more pores in the 10–100 nm diameter range in the modified carbide slag, facilitating rapid carbonation. Thus, the Mn/Ce-modified carbide slag exhibits good prospect for CaO/CaCO3 thermochemical energy storage.

Influence of multimodal fiber distribution on the permeability of fibrous media

This article deals with the impact of fiber size distribution on the permeability of nonwoven fibrous media, a major issue in the general field of filtration. The conventional method to determine the permeability of nonwoven fibrous media involves equating complex fibrous media with structures composed of a single equivalent fiber diameter. Based on numerical simulations of flow through tridimensional structures with polymodal and polydisperse fiber size distributions, we proposed a new equivalent diameter. In conjunction with a packing density function, the approach is compared to experimental data and simulations available in the scientific literature and shows better permeability predictions than other existing models for a wide range of solid volume fractions (1 % to 20 %) and fiber diameters (1.5 µm to 30 µm). This predictive model of permeability is an essential step in developing a decision-making tool for the design of fibrous media.

3D printed polymeric stent design: Mechanical testing and computational modeling

Polymer-based bioresorbable scaffolds (BRS) aim to reduce the long-term issues associated with metal stents. Yet, first-generation BRS designs experienced a significantly higher rate of clinical failures compared to permanent implants. This prompted the development of alternative scaffolds, such as the poly(L-lactide-co-ε-caprolactone) (PLCL) solvent-casted stent, whose mechanical performance has yet to be addressed. This study examines the mechanical behavior of this novel scaffold across a wide range of parallel and radial compression diameters. The analysis highlights the scaffold’s varying responses under different loading conditions and provides insights into interpreting simulation model parameters to accurately reflect experimental results.Stents demonstrated a parallel crush resistance of 0.11 N/mm at maximum compression, whereas the radial forces were significantly higher, reaching up to 1.80 N/mm. Additionally, the parallel test keeps the stent in the elastic regime, with almost no regions exceeding 50 MPa of stress, while the radial test causes significant structural deformation, with localized plastic strain reaching up to 30 %. Results showed that underestimating yield strain in computational models leads to discrepancies with experimental results, being 5 % the most accurate value for matching computational and experimental results for PLCL solvent-casted stents.This comprehensive approach is vital for optimizing BRS design and predicting clinical performance.

A comparative study on the optical performance of retro-reflective coatings before and after the aging process

Retro-reflective (RR) materials are largely included among the strategies to mitigate Urban Heat Island (UHI) phenomenon in the urban spaces thanks to their optical directional properties. As materials potentially used in the building exterior envelope, RR materials are subjected to outdoor aging and soiling processes, which could alter their optical behaviour. In this perspective, the investigation focuses on the characterization of the optical performance of several types of RR plaster coatings after outdoor aging and soiling processes. The RR plaster coatings were previously developed and studied, before undergoing the outdoor exposure. The RR samples were developed covering the support with a reflective white paint and glass beads. Five different microsphere diameter ranges and three different microsphere superficial density ranges have been employed. In this paper, the RR plaster coatings were tested in terms of optical properties after outdoor aging and soiling and results were compared with data of the same plaster coatings pre-aging. Generally, all RR aged samples show a lower solar reflectance in the Vis region with respect to the pre-aging conditions. The RR behaviour is qualitatively maintained after aging and soiling. The RR sample made of glass beads of 200–300 μm diameter range could represent the best solution both in pre- and post-conditions and both in terms of solar reflectance and retro-reflective behaviour, regardless of the density of microspheres used.

Validation of a radiosynthesis method and a novel quality control system for [68 Ga]Ga-MAA: is TLC enough to assess radiopharmaceutical quality?

BackgroundTechnetium-99 m-labelled macroaggregated human serum albumin ([99mTc]Tc-MAA) is commonly used for lung perfusion scintigraphy. The European Pharmacopoeia (Eu.Ph.) specifies thin-layer chromatography (TLC) as the only method to assess its radiochemical purity (RCP). Similarly, TLC is the sole method reported in the literature to evaluate the RCP of Gallium-68-labelled MAA [68 Ga]Ga-MAA, recently introduced for lung perfusion PET/CT imaging. Since [68 Ga]Ga-MAA is prepared from commercial kits originally designed for the preparation of [99mTc]Tc-MAA, it is essential to optimize and validate the preparation methods for [68 Ga]Ga-MAA.ResultsWe tested a novel, simplified method for the preparation of [68 Ga]Ga-MAA that does not require organic solvents, prewash or final purification steps to remove radioactive impurities. We assessed the final product using radio-TLC, radio-UV-HPLC, and radio SDS-PAGE. Overall, our quality control (QC) method successfully detected [68 Ga]Ga-MAA along with all potential impurities, including free Ga-68, [68 Ga]Ga-HSA, unlabeled HSA, which may occur during labelling process and HEPES residual, a non-toxic but non-human-approved contaminant, used as buffer solution. We then applied our QC system to [68 Ga]Ga-MAA prepared under different conditions (25°–40°–75°–95 °C), thus defining the optimal temperature for labelling. Scanning Electron Microscopy (SEM) analysis of the products obtained through our novel method confirmed that most [68 Ga]Ga-MAA particles preserved the morphological structure and size distribution of unlabeled MAA, with a particle diameter range of 25–50 μm, assuring diagnostic efficacy.ConclusionsWe optimized a novel method to prepare [68 Ga]Ga-MAA through a QC system capable of monitoring all impurities of the final products.

Ultra-sensitive liquefied petroleum gas (LPG) sensor based on monometallic Ag nanospheres synthesized via microwave-assisted facile approach

We present the synthesis, analysis, and utility of polyvinylpyrrolidone (PVP) stabilized monometallic silver nanospheres for liquefied petroleum gas sensing at room temperature. We have synthesised silver nanospheres (Ag-NSs) in the diameter range of 13–21 nm using a microwave assisted method, which is both easy and fast, because microwave irradiation only takes 30 s. A solution of 0.1 M silver nitrate (AgNO3) in an ethanolic medium was microwave-irradiated to produce Ag-NSs. PVP was used as a stabilising agent throughout the process. Spin coating method was used to produce thin films of synthesised monometallic Ag-NSs. X-ray diffraction (XRD), scanning electron microscopy (SEM), acoustic particle sizer (APS), UV–visible absorption (UV–visible) and Fourier Transform Infrared (FT-IR) spectroscopy were used for characterising Ag-NSs. Based on the acoustic attenuation of the prepared sample, the acoustic particle sizer estimated the diameter of Ag-NSs to be around 17 nm. The deposited films were examined for LPG leakage detection at ambient temperature. This is the first report on monometallic Ag-NSs for leakage detection of LPG at room temperature operation below its lower explosive limit (LEL). The significant finding of the developed sensor is that it prompts the quick response (∼16 s) and recovery (∼64 s) as Ag enhances the reaction rate between the sensing film surface and adsorbed LPG, thereby, augments the sensitivity of sensor even below LEL. Moreover, the fabricated LPG sensor shows noteworthy reproducibility (measured up to six cycles) and stability up to 06 months after fabrication.

On the potential of the Cluster Ion Counter (CIC) to observe local new particle formation, condensation sink and growth rate of newly formed particles

Abstract. The Cluster Ion Counter (CIC) is a simple three-channel instrument designed to observe ions in the electrical mobility equivalent diameter range from 1.0 to 5 nm. With the three channels, we can observe concentrations of both ion clusters (sub-2 nm ions) and intermediate ions. Furthermore, as derived here, we can estimate condensation sink (CS), intensity of local new particle formation, growth rate of newly formed particles from 2 to 3 nm and formation rate of 2 nm ions. We compared CIC measurements with those of a multichannel ion spectrometer, the Neutral cluster and Air Ion Spectrometer (NAIS), and found that the concentrations agreed well between the two instruments, with correlation coefficients of 0.89 and 0.86 for sub-2 nm and 2.0–2.3 nm ions, respectively. According to the observations made in Hyytiälä, Finland, and Beijing, China, the ion source rate was estimated to be about two to four ion pairs cm−3 s−1. The new CIC is a simple and cheap instrument that can be used in different environments to obtain information about small ion dynamics, local intermediate ion formation and CS in a robust way when combined with the theoretical framework presented here.

Node Reporting and Data System Combined With Computed Tomography Radiomics Can Improve the Prediction of Nonenlarged Lymph Node Metastasis in Gastric Cancer.

To investigate the diagnostic performance of Node Reporting and Data System (Node-RADS) combined with computed tomography (CT) radiomics for assessing nonenlargement regional lymph nodes in gastric cancer (GC). Preoperative CT images were retrospectively collected from 376 pathologically confirmed of gastric adenocarcinoma from January 2019 to December 2023, with 605 lymph nodes included for analysis. They were divided into training (n = 362) and validation (n = 243) sets. Radiomics features were extracted from venous-phase, and the radiomics score was obtained. Clinical information, CT parameters, and Node-RADS classification were collected. A combined model was built using machine-learning approach and tested in validation set using receiver operating characteristic curve analysis. Further validation was conducted in different subgroups of lymph node short-axis diameter (SD) range. Node-RADS score, SD, maximum diameter of thickness of tumor, and radiomics were identified as the most predictive factors. The results demonstrated that the integrated model combining SD, maximum diameter of thickness of tumor, Node-RADS, and radiomics outperformed the model excluding radiomics, yielding an area under the receiver operating characteristic curve of 0.82 compared with 0.79, with a statistically significant difference (P < 0.001). Subgroup analysis based on different SDs of lymph nodes also revealed enhanced diagnostic accuracy when incorporating the radiomics score for the 4- to 7.9-mm subgroups, all P < 0.05. However, for the 8- to 9.9-mm subgroup, the combination of the radiomics did not significantly improve the prediction, with an area under the receiver operating characteristic curve of 0.85 versus 0.85, P = 0.877. The integration of radiomics scores with Node-RADS assessments significantly enhances the accuracy of lymph node metastasis evaluation for GC. This combined model is particularly effective for lymph nodes with smaller standard deviations, yielding a marked improvement in diagnostic precision. The findings of this study indicate that a composite model, which incorporates Node-RADS, radiomics features, and conventional parameters, may serve as an effective method for the assessment of nonenlarged lymph nodes in GC.

Pushing boundaries in slurry microtunneling: Innovations in microtunnel boring machine design for hard rock conditions

AbstractFor microtunneling in hard rock, as it is encountered very often in alpine tunneling, the continuous further development of technologies plays a key role to overcome the limitations in drive length and to improve performance. During the last decades, the application range of slurry microtunneling has been considerably extended and more demanding projects have been designed for underground utilities installations worldwide, including many sewage tunnels and hydropower plants. The prevailing ground conditions still play a key role and determine the limits for alignment design and the possible use of trenchless construction methods. In hard rock conditions with high rock strength and/or abrasivity, the applicability of slurry microtunneling has been especially limited in the non‐accessible diameter range in the past. With the new AVN 800 HR for hard rock microtunneling, Herrenknecht has developed a machine concept, enabling drives of up to 200 m, with precise steering of the MTBM. Longer drives, even through hard rock, make microtunneling a more economic, flexible, and more environmentally friendly construction method. New opportunities for clients and consultants in the planning of tunnel routes in alpine environments for different infrastructure installations can be considered, making trenchless installations even more cost‐effective, while improving public acceptance.