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Stress field models for discontinuity regions in steel-reinforced laminated glass
No full textThis article presents the application of stress field models for strength prediction of discontinuity regions in steelreinforced glass structures failing due to crushing of the glass and failure of stainless steel reinforcement. One of the main assumptions in the proposed modelling approach is that the structural laminated glass has similar compressive features as high-strength concrete within a framework of the stress field method. The paper initially introduces theoretical and experimental aspects and similarities between compressive behaviour of glass and high-strength concrete. Considerations on the compressive strength of laminated glass as well as the softening effect of cracks through the transverse strain factor are presented. The softening effect of cracks is investigated using the results of bending tests on beams and detailed digital image correlation (DIC) measurements. Finally, the proposed models are compared with results of tests on steel-reinforced glass members encompassing local compressive tests, bending tests and tests on beam-column connections. Additionally, the three groups of tests are numerically simulated using elastic-plastic stress fields (EPSF), through the finite element (FE) software EvalS for the automatic development of 2D stress fields. This numerical tool was originally developed for design and assessment of RC discontinuity regions. It is found that the numerical predictions are in a good agreement with test results. It is concluded that the stress fields may serve as a tool for the verification of a post-fracture limit state.This article presents the application of stress field models for strength prediction of discontinuity regions in steelreinforced glass structures failing due to crushing of the glass and failure of stainless steel reinforcement. One of the main assumptions in the proposed modelling approach is that the structural laminated glass has similar compressive features as high-strength concrete within a framework of the stress field method. The paper initially introduces theoretical and experimental aspects and similarities between compressive behaviour of glass and high-strength concrete. Considerations on the compressive strength of laminated glass as well as the softening effect of cracks through the transverse strain factor are presented. The softening effect of cracks is investigated using the results of bending tests on beams and detailed digital image correlation (DIC) measurements. Finally, the proposed models are compared with results of tests on steel-reinforced glass members encompassing local compressive tests, bending tests and tests on beam-column connections. Additionally, the three groups of tests are numerically simulated using elastic-plastic stress fields (EPSF), through the finite element (FE) software EvalS for the automatic development of 2D stress fields. This numerical tool was originally developed for design and assessment of RC discontinuity regions. It is found that the numerical predictions are in a good agreement with test results. It is concluded that the stress fields may serve as a tool for the verification of a post-fracture limit state.A
tsdownsample : high-performance time series downsampling for scalable visualization
No full textInteractive line chart visualizations greatly enhance the effective exploration of large time series. Although downsampling has emerged as a well-established approach to enable efficient interactive visualization of large datasets, it is not an inherent feature inmost visualization tools. Furthermore, there is no library offering a convenient interface for high-performance implementations of prominent downsampling algorithms. To address these shortcomings, we present tsdownsample, an open-source Python package specifically designed for CPU-based, in-memory time series downsampling. Our library focuses on performance and convenient integration, offering optimized implementations of leading downsampling algorithms. We achieve this optimization by leveraging low-level Single Instruction, Multiple Data (SIMD) instructions and multithreading capabilities in Rust. In particular, SIMD instructions were employed to optimize the argmin and argmax operations. This SIMD optimization, along with some algorithmic tricks, proved crucial in enhancing the performance of various downsampling algorithms. We evaluate the performance of tsdownsample and demonstrate its interoperability with an established visualization framework. Our performance benchmarks indicate that the algorithmic runtime of tsdownsample approximates the CPU's memory bandwidth. This work marks a significant advancement in bringing high-performance time series downsampling to the Python ecosystem, enabling scalable visualization.Interactive line chart visualizations greatly enhance the effective exploration of large time series. Although downsampling has emerged as a well-established approach to enable efficient interactive visualization of large datasets, it is not an inherent feature inmost visualization tools. Furthermore, there is no library offering a convenient interface for high-performance implementations of prominent downsampling algorithms. To address these shortcomings, we present tsdownsample, an open-source Python package specifically designed for CPU-based, in-memory time series downsampling. Our library focuses on performance and convenient integration, offering optimized implementations of leading downsampling algorithms. We achieve this optimization by leveraging low-level Single Instruction, Multiple Data (SIMD) instructions and multithreading capabilities in Rust. In particular, SIMD instructions were employed to optimize the argmin and argmax operations. This SIMD optimization, along with some algorithmic tricks, proved crucial in enhancing the performance of various downsampling algorithms. We evaluate the performance of tsdownsample and demonstrate its interoperability with an established visualization framework. Our performance benchmarks indicate that the algorithmic runtime of tsdownsample approximates the CPU's memory bandwidth. This work marks a significant advancement in bringing high-performance time series downsampling to the Python ecosystem, enabling scalable visualization.A
Identification and investigation of the intrinsic receptor activation potential and metabolization of the new Oxo-Pyridyl synthetic cannabinoid receptor agonist CH-FUBBMPDORA
No full textCH-FUBBMPDORA (CHO-4 ' Me-5 ' Br-FUBOXPYRA), a recent addition to the recreational drug market, bypasses the Chinese generic ban (2021) on synthetic cannabinoid receptor agonists (SCRAs) due to its new 5-bromo-4-methylpyridin-2(1H)-one core. Its pharmacological properties are currently undefined, and it is yet to be found in biological samples. However, it is unclear whether this is due to low prevalence or hampered detection. The aim of this study was twofold. First, we used a powder seized by customs as a case study to evaluate the utility of low-field nuclear magnetic resonance (LF-NMR) to unequivocally identify CH-FUBBMPDORA. This demonstrated the potential of this technique, which is increasingly used by customs and forensic laboratories for substance identification. High-field nuclear magnetic resonance (HF-NMR), Fourier transform infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF-MS), and Raman spectroscopy were used as complementary techniques for identification and characterization. Second, we investigated the potential to activate CB1 and CB2 and the metabolism of CH-FUBBMPDORA. Potencies and efficacies were assessed using beta arr2 recruitment assays. Metabolite studies were conducted via human liver microsome (HLM) incubation followed by LC-QTOF-MS. CH-FUBBMPDORA showed a limited activation potential at both cannabinoid receptors. The seized powder exhibited a pronouncedly higher activity, suggesting the potential presence of contaminants with higher cannabinoid activity. Although analytical characterization revealed minor impurities, it is uncertain whether these explain the bioassay findings. Four metabolites were identified, which were all the result of hydroxylation of either the cyclohexyl head group or of the methyl group on the core.CH-FUBBMPDORA (CHO-4 ' Me-5 ' Br-FUBOXPYRA), a recent addition to the recreational drug market, bypasses the Chinese generic ban (2021) on synthetic cannabinoid receptor agonists (SCRAs) due to its new 5-bromo-4-methylpyridin-2(1H)-one core. Its pharmacological properties are currently undefined, and it is yet to be found in biological samples. However, it is unclear whether this is due to low prevalence or hampered detection. The aim of this study was twofold. First, we used a powder seized by customs as a case study to evaluate the utility of low-field nuclear magnetic resonance (LF-NMR) to unequivocally identify CH-FUBBMPDORA. This demonstrated the potential of this technique, which is increasingly used by customs and forensic laboratories for substance identification. High-field nuclear magnetic resonance (HF-NMR), Fourier transform infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF-MS), and Raman spectroscopy were used as complementary techniques for identification and characterization. Second, we investigated the potential to activate CB1 and CB2 and the metabolism of CH-FUBBMPDORA. Potencies and efficacies were assessed using beta arr2 recruitment assays. Metabolite studies were conducted via human liver microsome (HLM) incubation followed by LC-QTOF-MS. CH-FUBBMPDORA showed a limited activation potential at both cannabinoid receptors. The seized powder exhibited a pronouncedly higher activity, suggesting the potential presence of contaminants with higher cannabinoid activity. Although analytical characterization revealed minor impurities, it is uncertain whether these explain the bioassay findings. Four metabolites were identified, which were all the result of hydroxylation of either the cyclohexyl head group or of the methyl group on the core.A
Exploring mode of action for acute toxicity of primary aromatic amines with Daphnia magna using differential gene expression analysis
No full textThe diverse structures and modes of action (MOAs) of organic pollutants present a challenge in forecasting their environmental toxicity. Aromatic amines, widely used in industrial applications, are of particular interest due to their broad structural variation. Although they have been classified as polar narcotics, due to their narcotic MOA in fish, certain substitution patterns of the aromatically bound amino group exert excess toxicity towards species such as Daphnia magna. The underlying mechanisms bebind this phenomenon remain unclear. Therefore, we investigated how substitution patterns affect the MOA in this aquatic invertebrate. We used transcriptomics to study how three primary aromatic amines (PAAs), namely 4,4’-methylenedianiline (4,4’-MDA), 2,2’-methylenedianiline (2,2’-MDA) and 2,4-toluenediamine (2,4-TDA), affect D. magna. Our experimental design also included two reference compounds, 1-octanol (a non-polar narcotic) and aniline (a polar narcotic in fish, but excess toxicant in D. magna). Our analysis suggests very distinct biological MOAs for the three PAAs. While the para-substituted 4,4’-MDA treatment showed similar effects as the excess toxicant aniline, its ortho-substituted isomer 2,2’-MDA showed similar effects as the narcotic 1-octanol. Our results indicate a specific influence of substituent positioning in PAAs on their toxicity and MOA towards D. magna. This study illustrates the use of transcriptomics and its associated functional analysis to guide industrial chemical development towards more environmentally safe alternatives.The diverse structures and modes of action (MOAs) of organic pollutants present a challenge in forecasting their environmental toxicity. Aromatic amines, widely used in industrial applications, are of particular interest due to their broad structural variation. Although they have been classified as polar narcotics, due to their narcotic MOA in fish, certain substitution patterns of the aromatically bound amino group exert excess toxicity towards species such as Daphnia magna. The underlying mechanisms bebind this phenomenon remain unclear. Therefore, we investigated how substitution patterns affect the MOA in this aquatic invertebrate. We used transcriptomics to study how three primary aromatic amines (PAAs), namely 4,4’-methylenedianiline (4,4’-MDA), 2,2’-methylenedianiline (2,2’-MDA) and 2,4-toluenediamine (2,4-TDA), affect D. magna. Our experimental design also included two reference compounds, 1-octanol (a non-polar narcotic) and aniline (a polar narcotic in fish, but excess toxicant in D. magna). Our analysis suggests very distinct biological MOAs for the three PAAs. While the para-substituted 4,4’-MDA treatment showed similar effects as the excess toxicant aniline, its ortho-substituted isomer 2,2’-MDA showed similar effects as the narcotic 1-octanol. Our results indicate a specific influence of substituent positioning in PAAs on their toxicity and MOA towards D. magna. This study illustrates the use of transcriptomics and its associated functional analysis to guide industrial chemical development towards more environmentally safe alternatives.A
Impact of dorsal closing wedge calcaneal osteotomy on hindfoot alignment and biomechanics of patients with insertional achilles tendinopathy : a weightbearing CT-based simulation study
No full textPurposeDorsal closing wedge calcaneal osteotomy (DCWCO) is purported to enhance both the biological and mechanical aspects of insertional Achilles tendinopathy (IAT) by altering its insertional anatomy. The biomechanical impacts of shifting the Achilles insertion, however, are not fully understood. This study aimed to analyze the effect of DCWCO on hindfoot alignment and gastrocnemius-soleus (G-S) power.MethodsSix weightbearing ankle CTs of patients diagnosed with IAT were segmented and standardized planes were used to conduct DCWCOs with six variations, resulting in a total of 42-foot models including the 6 preoperative original model. Two distinct representations of plantar osteotomy starting points were defined. One was 1 cm anterior to plantar calcaneal tubercle (posterior osteotomy) and the other was 2 cm anterior (anterior osteotomy). The osteotomies were extended to 1 cm anterior of posterosuperior calcaneal tuberosity with 6-, 10-, or 14-mm dorsal wedges. Pre-defined Achilles insertion points were used to create computational Achilles tendon models. Multiple automated measurements were performed to calculate the change in foot alignment and biomechanics.ResultsBoth anterior and posterior osteotomy locations resulted in decreased lateral talocalcaneal and calcaneal pitch angles, more substantially so with the anterior osteotomy (p = 0.028). Distance change between Achilles and Haglund was much greater with posterior osteotomy using 6- and 10-mm wedges as compared to the anterior alternative (p = 0.028). Anterior osteotomy caused a significant decrease in the Böhler angle (p < 0.001). The subtalar joint orientation was observed to change up to 3.8° in anterior osteotomy and the decrease in G-S power was found to be a maximum of 2–3 %.ConclusionA posteriorly placed starting point can provide more Achilles decompression while an anteriorly placed starting point can affect foot alignment more significantly. DCWCO can change the subtalar joint orientation predisposing the joint to increased loads. Decrease in G-S power was low and will presumably not have clinical impact.PurposeDorsal closing wedge calcaneal osteotomy (DCWCO) is purported to enhance both the biological and mechanical aspects of insertional Achilles tendinopathy (IAT) by altering its insertional anatomy. The biomechanical impacts of shifting the Achilles insertion, however, are not fully understood. This study aimed to analyze the effect of DCWCO on hindfoot alignment and gastrocnemius-soleus (G-S) power.MethodsSix weightbearing ankle CTs of patients diagnosed with IAT were segmented and standardized planes were used to conduct DCWCOs with six variations, resulting in a total of 42-foot models including the 6 preoperative original model. Two distinct representations of plantar osteotomy starting points were defined. One was 1 cm anterior to plantar calcaneal tubercle (posterior osteotomy) and the other was 2 cm anterior (anterior osteotomy). The osteotomies were extended to 1 cm anterior of posterosuperior calcaneal tuberosity with 6-, 10-, or 14-mm dorsal wedges. Pre-defined Achilles insertion points were used to create computational Achilles tendon models. Multiple automated measurements were performed to calculate the change in foot alignment and biomechanics.ResultsBoth anterior and posterior osteotomy locations resulted in decreased lateral talocalcaneal and calcaneal pitch angles, more substantially so with the anterior osteotomy (p = 0.028). Distance change between Achilles and Haglund was much greater with posterior osteotomy using 6- and 10-mm wedges as compared to the anterior alternative (p = 0.028). Anterior osteotomy caused a significant decrease in the Böhler angle (p < 0.001). The subtalar joint orientation was observed to change up to 3.8° in anterior osteotomy and the decrease in G-S power was found to be a maximum of 2–3 %.ConclusionA posteriorly placed starting point can provide more Achilles decompression while an anteriorly placed starting point can affect foot alignment more significantly. DCWCO can change the subtalar joint orientation predisposing the joint to increased loads. Decrease in G-S power was low and will presumably not have clinical impact.A
Fingerprinting sediment sources using fallout radionuclides demonstrates that subsoil provides the major source of sediment in sub-humid Ethiopia
No full textPurposeTo mitigate erosion, soil and water conservation measures have been introduced widely, with the ambition to reduce on-site erosion rates and catchment sediment yield. However, the success of such measures has been questioned, and often lacks a scientific basis. This is especially true in Ethiopia where gullying has been reported to worsen because of the implementation of soil and water conservation programmes targeting sheet and rill erosion from cropland only. The current research therefore focuses on identifying the sources of sediment based on the dominant erosion processes at play.MethodsThis study was conducted in the Fota-Gumara catchment (211 km(2)), situated in the Lake Tana Basin. The investigation was based on the analysis of fallout radionuclides (137Cs and 210Pb-ex) tracers, which are able to discriminate between topsoil and subsoil. Target material consisted of sediment deposits collected during eight rainfall-runoff events, which occurred in the early and late rainy season of 2023. The activity of 137Cs and 210Pb was measured using gamma spectrometry, while the source apportionment was based on the implementation of Bayesian Models BMM and MixSIAR.ResultsOur findings confirmed that subsoil was the major source of sediment. Both models showed consistent results, indicating that approximately three-quarters of the sediment originates from subsoils, contributing a median average of 73% and 81% according to MixSIAR and BMM, respectively. Both the inter-event and seasonal variability of sediment source contributions were relatively low.ConclusionsWe conclude that gullies should be a land management priority. Additionally, we demonstrated the validity of using fallout radionuclides for tracing sediment sources in this region of tropical Africa.PurposeTo mitigate erosion, soil and water conservation measures have been introduced widely, with the ambition to reduce on-site erosion rates and catchment sediment yield. However, the success of such measures has been questioned, and often lacks a scientific basis. This is especially true in Ethiopia where gullying has been reported to worsen because of the implementation of soil and water conservation programmes targeting sheet and rill erosion from cropland only. The current research therefore focuses on identifying the sources of sediment based on the dominant erosion processes at play.MethodsThis study was conducted in the Fota-Gumara catchment (211 km(2)), situated in the Lake Tana Basin. The investigation was based on the analysis of fallout radionuclides (137Cs and 210Pb-ex) tracers, which are able to discriminate between topsoil and subsoil. Target material consisted of sediment deposits collected during eight rainfall-runoff events, which occurred in the early and late rainy season of 2023. The activity of 137Cs and 210Pb was measured using gamma spectrometry, while the source apportionment was based on the implementation of Bayesian Models BMM and MixSIAR.ResultsOur findings confirmed that subsoil was the major source of sediment. Both models showed consistent results, indicating that approximately three-quarters of the sediment originates from subsoils, contributing a median average of 73% and 81% according to MixSIAR and BMM, respectively. Both the inter-event and seasonal variability of sediment source contributions were relatively low.ConclusionsWe conclude that gullies should be a land management priority. Additionally, we demonstrated the validity of using fallout radionuclides for tracing sediment sources in this region of tropical Africa.A
Contrast-enhanced imaging of carbon fiber composites using hafnium oxide nanocrystals
No full textCarbon fiber-reinforced polymers (CFRPs) are of utmost importance in high-performance structural applications due to their unique combination of light-weight, yet high-strength behaviour. However, their behaviour and damage mechanisms are not fully understood. Damage propagation models need to take into account the type, geometry and orientation of a multitude of failure mechanisms and defects. Micro-Computed Tomography (micro-CT) data could provide the necessary input for these models, but the poor contrast between the carbon fibers and the polymer matrix does not allow automatic geometry extraction needed as input. To overcome this issue, hafnium oxide nanocrystals (HfO2 NCs) were introduced as CT contrast agents to the polymer matrix to provide the required contrast. To ensure a homogeneous and stable dispersion of the NCs in the epoxy resin, a bisphosphonic acid ligand consisting of ethylene glycol oligomer segments was used. The NCs did not significantly alter important parameters such as matrix stiffness, viscosity, glass transition temperature and curing time, enabling them to be implemented without having to alter current composite resin infusion methods. NC-doped CFRPs with 5 and 10 m% of HfO2 NCs added showed a drastic improvement in CT contrast, allowing for segmentation of the carbon fiber tows and visualization of micrometer-scale cracks. The contrast-enhanced NC-doped composites thereby enable the validation of damage models by accurate micro-CT data.Carbon fiber-reinforced polymers (CFRPs) are of utmost importance in high-performance structural applications due to their unique combination of light-weight, yet high-strength behaviour. However, their behaviour and damage mechanisms are not fully understood. Damage propagation models need to take into account the type, geometry and orientation of a multitude of failure mechanisms and defects. Micro-Computed Tomography (micro-CT) data could provide the necessary input for these models, but the poor contrast between the carbon fibers and the polymer matrix does not allow automatic geometry extraction needed as input. To overcome this issue, hafnium oxide nanocrystals (HfO2 NCs) were introduced as CT contrast agents to the polymer matrix to provide the required contrast. To ensure a homogeneous and stable dispersion of the NCs in the epoxy resin, a bisphosphonic acid ligand consisting of ethylene glycol oligomer segments was used. The NCs did not significantly alter important parameters such as matrix stiffness, viscosity, glass transition temperature and curing time, enabling them to be implemented without having to alter current composite resin infusion methods. NC-doped CFRPs with 5 and 10 m% of HfO2 NCs added showed a drastic improvement in CT contrast, allowing for segmentation of the carbon fiber tows and visualization of micrometer-scale cracks. The contrast-enhanced NC-doped composites thereby enable the validation of damage models by accurate micro-CT data.A
Study of flow-induced crystallization in polyvinylidene fluoride 3D printing
No full textThis study explores how additive manufacturing processes, specifically fused filament fabrication (FFF) parameters, affect the beta-crystallization of polyvinylidene fluoride (PVDF). A key focus is to ascertain if flow-induced crystallization during FFF improves the overall crystallinity, as the polymer melt is subjected to high shear forces during printing, which reduces kinetic barriers to crystallization and influences the resulting morphology. Using a design-of-experiments approach, the effects of extrusion temperature and printing speed were systematically evaluated to assess their impact on crystallinity, characterized through differential scanning calorimetry, Fourier-transform infrared spectroscopy, and polarized optical microscopy. Statistical analysis identified extrusion temperature as the most significant parameter for promoting beta-phase formation, with the highest crystallinity observed at an extrusion temperature of 235 degrees C. In contrast, printing speed appeared to have a limited influence on crystalline phase distribution, indicating that higher production rates may be achievable without adversely affecting material properties. Nevertheless, rheological investigations underscored the role of both extrusion temperature and printing speed in facilitating shear-induced crystallization. These findings provide valuable insights into the optimization of FFF parameters for PVDF-based functional devices, advancing the development of improved piezoelectric and energy harvesting applications while reducing the cost and complexity associated with conventional manufacturing techniques.This study explores how additive manufacturing processes, specifically fused filament fabrication (FFF) parameters, affect the beta-crystallization of polyvinylidene fluoride (PVDF). A key focus is to ascertain if flow-induced crystallization during FFF improves the overall crystallinity, as the polymer melt is subjected to high shear forces during printing, which reduces kinetic barriers to crystallization and influences the resulting morphology. Using a design-of-experiments approach, the effects of extrusion temperature and printing speed were systematically evaluated to assess their impact on crystallinity, characterized through differential scanning calorimetry, Fourier-transform infrared spectroscopy, and polarized optical microscopy. Statistical analysis identified extrusion temperature as the most significant parameter for promoting beta-phase formation, with the highest crystallinity observed at an extrusion temperature of 235 degrees C. In contrast, printing speed appeared to have a limited influence on crystalline phase distribution, indicating that higher production rates may be achievable without adversely affecting material properties. Nevertheless, rheological investigations underscored the role of both extrusion temperature and printing speed in facilitating shear-induced crystallization. These findings provide valuable insights into the optimization of FFF parameters for PVDF-based functional devices, advancing the development of improved piezoelectric and energy harvesting applications while reducing the cost and complexity associated with conventional manufacturing techniques.A
Single-step PA12/BN thermal conductive composite preparation using a corotating twin-screw 3D printing head based on material extrusion
No full textPurposeThis paper aims to develop an innovative 3D printer based on material extrusion to expand applied material field and shorten the production cycle. The developed 3D printer can fabricate products directly using various powders, including polymers and fillers. In addition, the influence of extrusion on the orientation of thermal conductive filler is also investigated.Design/methodology/approachTo ensure the plasticizing effect and the mixing ability, the printing head is a conical twin-screw extruder, which have a smaller volume. PA12 and h-BN powders were selected for printing as matrix and filler, respectively. The properties of printing products were characterized.FindingsThe results show that the new printer can fabricate products directly using polymer powders because of the mixing ability of the twin-screw. The h-BN filler orient in the PA12 matrix and form thermal conduction paths due to the extrusion process, which make the printed samples have an anisotropic thermal conductivity.Originality/valueThe innovative 3D printer provides a method of printing products directly using powders, which can expand material field and shorten the production cycle. For composites, the extrusion process can make fillers orient in the matrix to fabricate products with anisotropic characteristics.PurposeThis paper aims to develop an innovative 3D printer based on material extrusion to expand applied material field and shorten the production cycle. The developed 3D printer can fabricate products directly using various powders, including polymers and fillers. In addition, the influence of extrusion on the orientation of thermal conductive filler is also investigated.Design/methodology/approachTo ensure the plasticizing effect and the mixing ability, the printing head is a conical twin-screw extruder, which have a smaller volume. PA12 and h-BN powders were selected for printing as matrix and filler, respectively. The properties of printing products were characterized.FindingsThe results show that the new printer can fabricate products directly using polymer powders because of the mixing ability of the twin-screw. The h-BN filler orient in the PA12 matrix and form thermal conduction paths due to the extrusion process, which make the printed samples have an anisotropic thermal conductivity.Originality/valueThe innovative 3D printer provides a method of printing products directly using powders, which can expand material field and shorten the production cycle. For composites, the extrusion process can make fillers orient in the matrix to fabricate products with anisotropic characteristics.A