High Density Research Articles

Strength comparison for fully dense zirconium diboride ceramics tested by different methods

AbstractThe strength of zirconium diboride ceramics was tested by three different methods, 3‐point flexure, 4‐point flexure, and compression. Nearly full‐density ceramics were obtained by hot pressing commercial ZrB2 powder with the addition of .5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB2 milled with ZrB2 and WC media. Based on phase purity and higher thermal conductivity, ZrB2 ceramics prepared from powders milled with ZrB2 media were selected for mechanical property studies. The strength in 3‐point flexure was 546 ± 55 MPa. The flexure strength was 476 ± 41 MPa in 4‐point bending, which was ∼20% higher than the previously reported value of 398 MPa for ZrB2 with similar grain sizes due to higher relative density and lower impurity contents. Compression testing was performed at room temperature, and the strength was 1110 ± 358 MPa. Finally, the fracture toughness of pure ZrB2 ceramics was determined by the chevron‐notched beam method to be 3.6 ± .7 MPa m1/2. The strength and fracture toughness values are higher than those previously published for ZrB2 ceramics and can be attributed to higher density and lower grain size. The strength‐limiting flaw sizes were comparable to the grain size, suggesting that porosity and impurity phases did not play a significant role in the strength of these ceramics.

Identification of Land Use Mix Using Point-Based Geospatial Data in Urban Areas

Identifying land use mix (LUM) in urban areas is challenging, often requiring extensive human intervention and fieldwork. Accurate classification of LUM is crucial for various disciplines, including urban planning, urban economics, and public health. This study addresses this need by employing Voronoi triangulation and an entropy-based LUM formula using point-based geospatial data collected from publicly available sources. The methodology was tested in two distinct urban settings: Ankara and Kadıköy. Ankara, the capital city, provides a large and diverse urban environment, while Kadıköy, a district in Istanbul known for its dynamic urban life, offers a contrasting scenario. Results were analyzed concerning local spatial autocorrelation and point of interest (POI) intensity. The comparative analysis demonstrated that the approach performs well across different urban contexts, with improved results observed in Kadıköy due to its higher density of mixed-use development. Specifically, we managed to identify mixed land use areas with an accuracy of up to 78% and an F1-score of 83% in urban regions. These findings highlight the robustness and applicability of our approach in diverse urban environments, providing valuable insights for city planners and policymakers in optimizing the allocation of urban resources and enhancing land use efficiency.

Phenotyping COVID-19 respiratory failure in spontaneously breathing patients with AI on lung CT-scan

BackgroundAutomated analysis of lung computed tomography (CT) scans may help characterize subphenotypes of acute respiratory illness. We integrated lung CT features measured via deep learning with clinical and laboratory data in spontaneously breathing subjects to enhance the identification of COVID-19 subphenotypes.MethodsThis is a multicenter observational cohort study in spontaneously breathing patients with COVID-19 respiratory failure exposed to early lung CT within 7 days of admission. We explored lung CT images using deep learning approaches to quantitative and qualitative analyses; latent class analysis (LCA) by using clinical, laboratory and lung CT variables; regional differences between subphenotypes following 3D spatial trajectories.ResultsComplete datasets were available in 559 patients. LCA identified two subphenotypes (subphenotype 1 and 2). As compared with subphenotype 2 (n = 403), subphenotype 1 patients (n = 156) were older, had higher inflammatory biomarkers, and were more hypoxemic. Lungs in subphenotype 1 had a higher density gravitational gradient with a greater proportion of consolidated lungs as compared with subphenotype 2. In contrast, subphenotype 2 had a higher density submantellar–hilar gradient with a greater proportion of ground glass opacities as compared with subphenotype 1. Subphenotype 1 showed higher prevalence of comorbidities associated with endothelial dysfunction and higher 90-day mortality than subphenotype 2, even after adjustment for clinically meaningful variables.ConclusionsIntegrating lung-CT data in a LCA allowed us to identify two subphenotypes of COVID-19, with different clinical trajectories. These exploratory findings suggest a role of automated imaging characterization guided by machine learning in subphenotyping patients with respiratory failure.Trial registration: ClinicalTrials.gov Identifier: NCT04395482. Registration date: 19/05/2020.

Comparative study of low-density versus high-density pedicular screw implantations in management of adolescent idiopathic scoliosis: a randomized clinical trial

BackgroundA number of studies have yielded disparate findings regarding the relationship between implant density and curve correction in adolescent idiopathic scoliosis (AIS) surgery. This study compared the efficacy and safety of low-density (LD) versus high-density (HD) pedicular screw implants in the correction of deformity in AIS regarding clinical, radiological, and quality of life outcomes. MethodsThis study was a single-blind, parallel, randomized trial that enrolled 20 adolescent patients with idiopathic scoliosis scheduled for posterior spinal fusion surgery with all pedicle screw constructs. Patients were randomized into two groups of 10 patients each. The LD group included patients in whom the number of screws per fused spinal level had a density of 1.5 or less, while the HD group had a density greater than 1.5. The primary outcomes were the radiological findings of curve correction. The secondary outcomes included the correlation between implant density and curve correction, the amount of blood loss, operation time, number of screws, fusion level, hospital stay duration, and quality of life assessed by the Scoliosis Research Society 22r questionnaire. ResultsRadiologically, the postoperative main curves Cobb angles and their changes were comparable between both approaches without statistical correlation with the implant density (p˃0.05). The LD approach significantly shortened the operative time (p=0.015), number of screws (p=0.011), implant density (p<0.001), and hospital stay (p<0.001). However, quality of life scores before surgery and at final follow-up did not differ between the two techniques (p˃0.05). ConclusionsThe use of a low-density approach is an effective and safe methodology for attaining satisfactory deformity correction in AIS patients. Furthermore, this approach confers the additional advantage of reduced operative time, number of screws, implant density, and hospital stay in comparison to the high-density approach.Trial registration Pan African Clinical Trial Registry, PACTR202404611444119. Registered 28 March 2024-Retrospectively registered, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=29382

Fluid flow zones along fracture corridors inferred from collapse dolines in carbonates of the Irecê Basin, Brazil

AbstractDolines are a widespread karst landform, and understanding their genesis can provide critical information about the evolution of subsurface karstification and groundwater flow zones. Swarms of collapse dolines characterise the karst in the southern portion of the Irecê Basin, northeastern Brazil. The basin comprises Neoproterozoic carbonate rocks approximately 100 m thick, bounded by less soluble older quartzites. The distribution of dolines is not uniform, as they cluster along NW‐SE axes and are aligned with cave systems and permeability (fracture) corridors mostly associated with the Almas and Água de Rega ephemeral rivers. Detailed analysis of sectors with a higher density of dolines was performed using LiDAR and unmanned aerial vehicle (UAV) imagery at two different scales to obtain morphometric and orientation patterns. As expected, scale dependency is observed, with an increase in density and circularity index at a higher resolution scale, but a decrease in mean area and perimeter. However, Voronoi polygon indices are similar at both scales (6.86 ± 1); the departure from the more stable number of six due to the clustering of dolines associated with NW‐SE oriented structural trends. Doline density trends closely follow the orientation of caves, but they are not always spatially connected, since doline evolution may either occlude the caves or be related to a non‐identified void. The Irecê Basin karst system displays a continuum of landforms evolving initially from high‐density fracture zones (fracture corridors), which work as favourable dissolution zones, grading into more integrated flow routes, cave systems and eventually clusters of collapse dolines. Collapse dolines are widespread karst landforms worldwide, and their genesis requires the presence of dissolution voids at depth, which may pass undetected from the surface. In some sectors of Irecê Basin, the existence of doline alignments but the absence of known caves indicates the potential of collapse dolines to be used as proxies for subsurface karstification. Such an approach may allow the prediction of the location and orientation of subsurface zones of enhanced dissolution that can potentially represent productive aquifers or favourable zones for geofluids.

Epicardial adipose tissue volume and density are associated with heart failure with improved ejection fraction

BackgroundHeart failure (HF) with improved ejection fraction (EF, HFimpEF) is a distinct HF subtype, characterized by left ventricular (LV) reverse remodeling and myocardial functional recovery. Multiple cardiometabolic factors are implicated in this process. Epicardial adipose tissue (EAT), emerging as an endocrine and paracrine organ, contributes to the onset and progression of HF. However, the relation between EAT and the incidence of HFimpEF is still unclear.MethodsA total of 203 hospitalized HF patients with reduced EF (HFrEF, LVEF ≤ 40%) who underwent coronary CT angiography (CCTA) during index hospitalization were consecutively enrolled between November 2011 and December 2022. Routine follow-up and repeat echocardiograms were performed. The incidence of HFimpEF was defined as (1) an absolute LVEF improvement ≥ 10% and (2) a second LVEF > 40% (at least 3 months apart). EAT volume and density were semiautomatically quantified on non-enhanced series of CCTA scans.ResultsDuring a median follow-up of 8.6 (4.9 ~ 13.3) months, 104 (51.2%) patients developed HFimpEF. Compared with HFrEF patients, HFimpEF patients had lower EAT volume (115.36 [IQR 87.08 ~ 154.78] mL vs. 169.67 [IQR 137.22 ~ 218.89] mL, P < 0.001) and higher EAT density (-74.92 ± 6.84 HU vs. -78.76 ± 6.28 HU, P < 0.001). Multivariate analysis showed lower EAT volume (OR: 0.885 [95%CI 0.822 ~ 0.947]) and higher density (OR: 1.845 [95%CI 1.023 ~ 3.437]) were both independently associated with the incidence of HFimpEF. Subgroup analysis revealed that the association between EAT properties and HFimpEF was not modified by HF etiology.ConclusionsThis study reveals that lower EAT volume and higher EAT density are associated with development of HFimpEF. Therapies targeted at reducing EAT quantity and improving its quality might provide favorable effects on myocardial recovery in HF patients.Graphical abstract

A comparison of the quality of UHT milk and its plant-based analogs

The aim of this study was to compare selected physical (density) and physicochemical (color, pH, titratable acidity) properties and the fatty acid profile of dairy UHT milk and its plant-based analogs, i.e., almond, soy, rice, oat, and coconut beverages. Ten products of each type were analyzed in each group. UHT milk was characterized by higher values of color lightness (L*) and titratable acidity than all plant-based milk alternatives, higher yellowness (b*) than rice drink, higher density than almond drink, and higher pH than rice and coconut drinks. In comparison with UHT milk, all plant-based beverages were characterized by higher redness (a*), soy drink was characterized by higher values of b* and chroma (C*), and almond and soy drinks had higher pH values. In the group of non-dairy beverages, the values of b* and C* were highest in soy drink, and the value of a* was highest in almond drink. Almond drink had the highest pH value, and soy and coconut drinks had the highest titratable acidity. Rice drink had higher density than oat, soy and almond drinks. The indicators characterizing the nutritional value of fat were considerably lower in coconut drink and dairy milk than in the remaining products. The values of UFA/SFA, MUFA/SFA, and DFA/OFA ratios and the indicator of nutritional value were highest in rice drink. The PUFA/SFA ratio and the total content of EFAs were highest in soy drink, and the n-6/n-3 PUFA ratio was highest in almond drink.

The effect of soil parameters and earthworm abundance on the fine-scale nocturnal habitat use of the Eurasian woodcock (Scolopax rusticola).

The Eurasian woodcock prefers habitats where its main prey, earthworms, can be found in higher densities. Although they are forest-dwelling birds, they regularly visit pastures and natural grasslands at night, where earthworm abundance is generally higher. However, there is little information on fine-scale habitat use in relation to variation in habitat characteristics and prey availability, particularly beyond the breeding season. In our study, we investigated if the nocturnal occurrence of woodcocks during migratory stopover periods differed between two neighbouring fields, or management units, with similar vegetation structure, and if within-field variation in the spatial patterns of woodcock sightings were associated with fine-scale earthworm densities and soil parameters. Specifically, we used GPS tracking data of two tagged woodcocks and direct observation data to study patterns of occurrence of birds in a mixed forest-pasture landscape in Hungary during pre- and post-breeding periods. We compared these patterns with fine-scale soil characteristics and earthworm abundance, acquired by field sampling. We found that the field with higher earthworm abundance was visited by woodcocks more frequently, and this correlation was similarly observed at the intra-field level. Our results demonstrate that woodcocks select foraging sites with higher earthworm densities at multiple spatial scales, both between fields (coarse scale), and within fields (fine-scale). Considering that woodcocks tended to return to the same field to forage at night, the strong associations between occupancy and resources provide a basis for developing habitat management strategies at the field level for conservation. As earthworm densities and soil parameters are good indicators of woodcock foraging habitat, measuring those variables, at least at a coarse scale, could aid in predicting important habitats for the species across the landscape.

Optical Coherence Tomography Angiography Retinal Imaging Associations With Burden of Small Vessel Disease and Amyloid Positivity in the Brain.

Alzheimer disease (AD) and other dementias are associated with vascular changes and amyloid deposition, which may be reflected as density changes in the retinal capillaries. These changes may can be directly visualized and quantified with optical coherence tomography angiography (OCTA), making OCTA a potential noninvasive preclinical biomarker of small vessel disease and amyloid positivity. Our objective was to investigate the feasibility of retinal imaging metrics as noninvasive biomarkers of small vessel disease and amyloid positivity in the brain. We investigated associations between OCTA and neuroimaging and cognitive metrics in 41 participants without dementia from the Mayo Clinic Study of Aging and Alzheimer's Disease Research Center. OCTA metrics included superficial, deep, and full retina capillary density of the fovea, parafovea, and macula as well as the area of the foveal avascular zone (FAZ). Neuroimaging metrics included a high burden of white matter hyperintensity (WMH), presence of cerebral microbleeds (CMB), lacunar infarcts, and amyloid positivity as evidenced on positron emission tomography (PET), whereas cognitive metrics included mini-mental status examination (MMSE) score. We performed generalized estimating equations to account for measurements in each eye while controlling for age and sex to estimate associations between OCTA metrics and neuroimaging and cognitive scores. Associations between OCTA and neuroimaging metrics were restricted to the fovea. OCTA showed decreased capillary density with high burden of WMH in both the superficial (P = 0.003), deep (P = 0.004), and full retina (P = 0.01) in the fovea but not the parafovea or whole macula. Similarly, participants with amyloid PET positivity had significantly decreased capillary density in the superficial fovea (P = 0.027) and deep fovea (P = 0.03) but higher density in the superficial parafovea (P = 0.038). Participants with amyloid PET positivity also had a significantly larger FAZ (P = 0.031), whereas in those with high WMH burden the difference did not reach statistical significance (P = 0.075). There was also a positive association between MMSE and capillary density of the full retina within the fovea (P = 0.037) and in the superficial parafovea (P = 0.046). No associations were found between OCTA metrics and presence of CMB or presence of lacunar infarcts. The associations of lower foveal capillary density with cerebral WMH and amyloid positivity suggest that further research is warranted to evaluate for shared mechanisms of disease between small vessel disease and AD pathologies.

Influence of hydroxyl group density in propane alcohols-based deep eutectic solvents: Physicochemical properties and potential application as an extraction medium for bioactive compounds

Deep eutectic solvents (DES) composed of citric acid monohydrate (CAM) as hydrogen bond acceptor (HBA) and alcohol as hydrogen bond donor (HBD) were used for separating bioactive compounds from star anise. This study prepared three propane alcohols-based DES with different hydroxyl (OH) group densities in HBD. FTIR analysis verified the presence of hydrogen bond interactions between HBA and HBD, which strengthened with increasing the OH group densities. Increasing the OH group density in DES exhibited lower water content, but higher thermal stability, higher density, higher viscosity as well as enhanced the water absorption rate. All of the propane alcohols-based DES were miscible in high and semi-polar solvents as well as it also displayed frequency independence characteristics. Moreover, propane alcohols-based DES efficiently extracted bioactive compounds from star anise with high total phenolic and flavonoid contents more than traditional solvents. High bioactive phenolic and flavonoid contents in star anise extracts were the major contributors to potent antioxidant activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH, 84.50 %), azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, 85.73 %), and ferric ion reducing antioxidant power (FRAP, 3.74 mM FeSO4). Therefore, DES was suggested to be a promising extraction medium for valuable bioactive compounds from natural sources that could be utilized as therapeutic agent for oxidative stress.

Modeling of Microplastics Migration in Soil and Groundwater: Insights into Dispersion and Particle Property Effects.

Migration of microplastics (MPs) in soil-groundwater systems plays a pivotal role in determining its concentration in aquifers and future threats to the terrestrial environment, including human health. However, existing models employing an advection-dispersion equation are insufficient to incorporate the holistic mechanism of MP migration. Therefore, to bridge the gap associated with MP migration in soil-groundwater systems, a dispersion-drag force coupled model incorporating a drag force on MPs along with dispersion is developed and validated through existing laboratory and field-scale experiments. The inclusion of the MP dispersion notably increased the global maximum particle velocity (vmaxp) of MPs, resulting in a higher concentration of MPs in the aquifer, which is also established by sensitivity analysis of MP dispersion. Additionally, increasing irrigation flux and irrigation areas significantly accelerates MP migration downward from soil to deep saturated aquifers. Intriguingly, vmaxp of MPs exhibited a nonlinear relationship with MPs' sizes smaller than 20 μm reaching the highest value (=1.64 × 10-5 m/s) at a particle size of 8 μm, while a decreasing trend was identified for particle sizes ranging from 20 to 100 μm because of the hindered effect by porous media and the weaker effect of the drag force. Moreover, distinct behaviors were observed among different plastic types, with poly(vinyl chloride), characterized by the highest density, displaying the lowest vmaxp and minimal flux entering groundwater. Furthermore, the presence of a heterogeneous structure with lower hydraulic conductivity facilitated MP dispersion and promoted their migration in saturated aquifers. The findings shed light on effective strategies to mitigate the impact of MPs in aquifers, contributing valuable insights to the broader scientific fraternity.

Multiobjective Optimization of High Power Density Outer Rotor PM Starter Generator Considering Electromagnetic and Temperature Characteristics

Multiobjective Optimization of High Power Density Outer Rotor PM Starter Generator Considering Electromagnetic and Temperature Characteristics

High Current Density Cables for Simpler HTS Magnets in Fusion Energy Systems

High Current Density Cables for Simpler HTS Magnets in Fusion Energy Systems

Numerical study of granulation in anelastic thermal convection in spherical shells

The present work investigates granulation or convective flow patterns in density-stratified (or anelastic) convection in spherical shells. The density-stratified thermal convection is typically present in astrophysical systems (such as solar convection); motivated by this, we performed a series of three-dimensional anelastic convection simulations in a spherical shell geometry using an in-house developed hybrid solver. We explored the effect of Rayleigh number and density scale height on the convective flow patterns. The granulation (or cell-like structures) are more prominent at higher density scale height and Rayleigh number. The granulation is further characterized by kinetic energy and helicity spectra. Our results support the argument that the convective flow patterns (or granulation) emerge due to inverse cascade owing to the presence of density stratification. Convective patterns (or granulation) are identified based on length scales, time scales, and flow velocity. The length scale of granules is further verified using a solar granulation model. Our analysis suggests the existence of inverse cascade and supergranulation on the spherical surface due to density-stratified thermal convection in spherical shells.

PD-L1+ macrophage and tumor cell abundance and proximity to T cells in the pretreatment large B-cell lymphoma microenvironment impact CD19 CAR-T cell immunotherapy efficacy.

CD19-targeted chimeric antigen receptor T-cell (CAR-T) immunotherapy has transformed the management of relapsed/refractory large B-cell lymphoma (LBCL), yet durable remissions are observed in less than half of treated patients. The tumor microenvironment (TME) is a key and understudied factor impacting CD19 CAR-T therapy outcomes. Using NanoString nCounter transcriptome profiling (n = 24) and multiplex immunohistochemistry (mIHC, n = 15), we studied the TME in pretreatment biopsies from patients with LBCL undergoing CD19 CAR-T therapy. Patients who achieved complete response (CR) after CAR-T therapy demonstrated higher expression of genes associated with T-cell trafficking and function, whereas those who did not achieve CR had higher expression of genes associated with macrophages and T-cell dysfunction. Distinct patterns of immune infiltration and fibrosis in the TME were associated with CAR-T therapy outcomes, and these findings were corroborated using artificial intelligence-assisted image analyses. Patients who achieved CR had a lower proportion of the biopsy occupied by an interspersed immune infiltrate and a higher proportion of hypocellular/fibrotic regions. Furthermore, mIHC revealed lower density of CD4+ T cells and higher densities of both macrophages and tumor cells expressing PD-L1 in non-CR patients. Spatial analysis revealed that PD-1+ T cells were in close proximity to PD-L1+ macrophages or PD-L1+ tumor cells in patients who did not compared to those who did achieve CR after CAR-T therapy. These findings suggest that morphologic patterns in the TME and engagement of the PD-1/PD-L1 axis in pretreatment biopsies may impact CD19 CAR-T immunotherapy response in patients with LBCL.

Morphological characteristics of the cerebral cortex of a mini-pig under conditions of gene therapy after experimental stroke

Aim. To study the effectiveness of preventive gene therapy (within 2 days) and gene therapy in the acute phase (after 4 hours) of ischemic stroke in mini-pigs using an autologous leucoconcentrate (AutoLeuc) enriched with recombinant genes of vascular endothelial growth factor (VEGF165), glial cell line-derived neurotrophic factor (GDNF) and neural cell adhesion molecule 1 (NCAM1), as well as the migration of leukocytes transduced with a chimeric adenoviral vector serotype 5 with fiber 35 serotype (Ad5/F35) and the green fluorescent protein (GFP) genome into immune defense organs.Materials and methods. The experiment was conducted on 8-month-old Vietnamese lop-bellied mini-pigs (n=16). An ischemic stroke was created by occlusion of the distal branches of the left middle cerebral artery and the right common carotid artery. Genetically modified AutoLeuc was administered preventively intravenously 2 days before or in the acute phase 4 hours after stroke modelling; the control group was injected with 30 ml of saline solution. The morphology of the cerebral cortex was assessed using histological methods in the areas bordering the infarction and peri-infarction after 21 days. The migration of genetically modified Ad5/F35-GFP leukocytes into the brain, spleen, and submandibular lymph nodes was studied a week after stroke modelling.Results. In the peri-infarction zone, the content of pyknotic neurons in control animals was higher, while the number of capillaries was lower than in the gene therapy groups. In the latter, neurons had a typical morphology with preserved outgrowths; in the control group, the outgrowths were tortuous and fragmented. Fluorescence microscopy after injection of AutoLeuc with Ad5/F35-GFP revealed GFP-positive cells in the spleen and submandibular lymph nodes.Conclusion. 21 days after modeling a stroke in mini-pigs against the background of preventive gene therapy or gene therapy in the acute phase using VEGF165/GDNF/NCAM1 AutoLeuc, greater preservation of neurons and a higher density of capillaries in the peri-infarction zone of ischemic brain damage were established. Leukocytes with Ad5/ F35-GFP were found in the spleen and submandibular lymph nodes.

Quantitative assessment of enlarged perivascular spaces via deep-learning in community-based older adults reveals independent associations with vascular neuropathologies, vascular risk factors, and cognition

Abstract Enlarged perivascular spaces (EPVS) are common in older adults, but their neuropathologic correlates are unclear mainly because most work to date has relied on visual rating scales and/or clinical cohorts. The present study first developed a deep learning model for automatic segmentation, localization and quantification of EPVS in ex-vivo brain MRI, and then used this model to investigate the neuropathologic, clinical, and cognitive correlates of EPVS in 817 community-based older adults that underwent autopsy. The new method exhibited high sensitivity in detecting EPVS as small as 3 mm3, good segmentation accuracy and consistency. Most EPVS were located in the frontal lobe, but the highest density was observed in the basal ganglia. EPVS in the cerebrum and specifically in the frontal lobe were associated with infarcts independent of other neuropathologies, while temporal and occipital EPVS were associated with cerebral amyloid angiopathy. EPVS in most brain lobes were also associated with diabetes mellitus independently of neuropathologies, while basal ganglia EPVS were independently associated with hypertension, supporting the notion of independent pathways from diabetes and hypertension to EPVS. Finally, EPVS were associated with lower cognitive performance independently of neuropathologies and clinical variables, suggesting that EPVS represent additional abnormalities contributing to lower cognition.

Spatial and temporal variability of fouling communities on oyster spat collectors at Inhaca Island Southern Mozambique: Exploring the influence on recruitment of the oysters Pinctada capensis and Saccostrea cucullata

In the transition from pelagic larva to benthic adult, larvae likely encounter a diverse assemblage of resident invertebrates in their habitat, which may also compete for space during post-settlement periods. Fouling fauna in rocky and seagrass habitats on Inhaca Island, southern Mozambique, was evaluated over 4 months in each of two seasons on oyster collectors fixed at 2 cm above the bottom. As expected, two species of oysters recruited to tiles: the rock oyster Saccostrea cucullata in rocky habitats and the pearl oyster, Pinctada capensis in seagrass habitats. The composition and density of other fouling fauna varied among habitats, location, seasons and surfaces and depending on the duration of the deployment. In seagrass habitats, oysters and barnacles were generally less abundant, allowing other taxa to have higher relative abundance, while higher density of individuals was recorded in rocky habitat. Barnacles dominate among fouling fauna on collectors in both habitats. Despite evidence consistent with negative interactions between oysters and barnacles, the effects of other fouling fauna on oyster abundance appear modest up to 4 months after tiles are placed. Overall, the results help improve our general understanding of the environmental processes that affect the colonisation of intertidal invertebrates, particularly in the southwestern Indian Ocean.

Exploring the impact of diesel-vegetable oil blends as an alternative fuel in combustion chambers

This study investigated using diesel-vegetable oil blends as an alternative fuel in combustion chambers. Vegetable oils, such as soybean and rapeseed oil, were blended with diesel fuel to create different blends, and the resulting properties were studied. It was found that vegetable oil blends had higher densities and flash points than pure diesel, which may affect combustion. Adding vegetable oil to the fuel reduced NOx and particulate matter emissions but had no significant impact on CO and CO2 emissions. Blends of vegetable oils were identified as promising alternative fuels for combustion chambers. In the experimentation, a combustion chamber was equipped with six swirl blades comprising two curved and one straight blade fired at different swirl angles (20°, 30°, 40°, 50°, and 60°) using VR1, VR2, VR3, and VR4 mix ratios of the blends. The results revealed that the maximum temperature for straight-edge blades was 50 °C, while curved-edge blades achieved a maximum temperature of 60 °C. Notably, due to the higher density and flash point of DIRO compared to DISO, the maximum temperatures of DISO blends tended to surpass those of DIRO blends. Furthermore, the study highlighted the superior combustion characteristics of curved blades, attributed to their swirling curved edges that elevated temperatures and enhanced turbulence. The optimal temperature was achieved using a 60 °C curved-edge blade swirling at a VR1 blend ratio in the DISO blend. Further exploration into additional features like pressure, emissions, and flame characteristics could contribute to supporting the use of these oil blends in diverse applications.

Impact of sudden public crises on spatial distribution patterns and driving factors of the urban catering industry: a case study of Shanghai’s catering POI data before and after COVID-19

ABSTRACT This study uses Shanghai to explore the effects of the COVID-19 pandemic on the spatial distribution patterns and driving factors of the urban catering industry. Through quantitative analysis of restaurant point-of-interest data and influencing factors in Shanghai’s main urban area from 2016 to 2022 using geographic information technology, machine learning, and spatial econometric models, this study predicts spatial changes in the catering industry. The number of restaurants in Shanghai’s main urban area continuously decreased from 2016 to 2022, with a significant pre-pandemic decline. The catering industry in this area has a significant spatial correlation in the spatial distribution, showing a pattern of “one core dominance with multiple cores coexisting,” with Jing’an and Huangpu Districts having the highest densities, which is expected to continue. Target markets remain a decisive factor in restaurant location selection post-COVID. Restaurant aggregation is most favorable when the population density is between 0 –50,000 people/km2, GDP is between 0–20 billion yuan/km2, housing prices are between 20,000 –130,000 yuan/m2, school density is between 0–20/km2, hospital density is between 0–10/km2, and attraction density is between 0–40/km2. Transportation conditions have no apparent threshold; the more developed the transportation, the more favorable the conditions for the catering industry. Post-COVID-19, areas with high housing prices and around tourist attractions are less likely to attract many restaurants. Areas around hospitals maintain restaurant aggregation, although this will decrease. Areas around schools will become popular for restaurants in the future.