Density Analysis Research Articles

Probability Density Analysis Reveals Substantial Differences Between the Dinitrogen and Acetylene Triple Bonds.

In earlier publications, it was shown that the electron positions maximizing the probability density resemble the Lewis structures for most small molecules. While this holds for the triple bond in acetylene, this is not the case for the triple bond in dinitrogen. Because of recent advances in studying the topology of wave functions, this peculiar case is revisited. In this work, the dinitrogen wave function is analyzed and compared to that of acetylene. Significant differences of the electron positions maximizing are uncovered and explained by the presence of hydrogen atoms in acetylene and by electron arrangements resulting from calculations of the nitrogen and carbon atoms. Moreover, insights into the electron delocalization of both molecules are gained by investigating electron exchange paths. Considering the different chemical behaviors of dinitrogen and acetylene, these differences should be expected.

Mechanical characterization of sandwich composite structures with Alumix231 foam core between Al2024/B4C composite plates

Abstract The study investigates the production of lightweight B4C particle-reinforced aluminum sandwich foam (ASF) materials, crucial for high impact and corrosion resistance, particularly in defense and automotive sectors. These materials are manufactured via powder metallurgy. Five different combinations of ASF materials, layered and unlayered with B4C, were examined. Alumix231 served as the primary material in the Al foam, with TiH2 as the blowing agent. In layered ASF materials, Al2024 powder acted as the main material, reinforced by B4C particles. Samples with various configurations, including foam, foam/Al2024 layers, and 5-10–20 % B4C particle-reinforced Al2024 layers, were produced. After powder mixing, they were filled into a hot pressing mold, pre-pressed at 25 MPa, dwelled at 550 °C for 30 min, then hot pressed at 200 MPa to form foamable preform material. B4C particle-layered ASF materials were generated by foaming the preforms in a steel mold at 750 °C for 11 min. Microstructure, density, pore size, and morphology analyses were conducted. Al2024 exhibited the highest density at 99 %, decreasing with increased B4C ratio. With more B4C, compressibility decreased, and agglomeration increased. Pores were observed around TiH2 and Si particles in B4C-lacking materials. The material with the best homogeneity and spherical pore resemblance was noted as Alumix231.

Flecking of fat-filled milk powders.

Flecking is an insolubility issue in fat-containing milk powders. The undissolved particles (flecks) are of different shapes and structures, primarily composed of fat and/or protein. The occurrence of flecking in reconstituted milk powders negatively impacts the visual appearance and overall quality of the final product, thereby influencing consumer acceptance and brand trust. Standard quality control measures, like wettability or insolubility, and analysis including rehydration testing are important but not sufficient in predicting, identifying and/or quantifying flecking, often necessitating additional measures to be implemented. Suitable additional analyses for flecking include confocal laser scanning microscopy, electron microscopy, particle size, and density analysis. However, it is crucial to highlight that merely tightening quality control parameters is insufficient to combat flecking. This approach does not allow for the implementation of rapid solutions when the issue is detected at the final stages of quality assessment. To effectively address fleck formation, it is necessary to scrutinize unit operations and identify precisely where, and how, in the process flecks are formed. The issue often requires reformulation and/or engineering interventions, making the final product more robust and resilient to fleck formation. To date, protein denaturation/aggregation and emulsion instability are proposed as major mechanisms governing fleck formation. Additionally, the effect of seasonality of milk chemical composition and reconstitution medium (water/coffee/tea) are other important factors. This work aims to review flecking in reconstituted fat-filled milk powder solutions by interrogating the production process, including the skim milk base wet and dry processing, alongside the powder storage conditions and reconstitution methods, and thereby identify strategies for the control of flecking.

Discovery of iron-oxo-catalyzed oxidation of fluorophenyl systems to carbonyls or epoxides: reactive intermediates determined mechanism.

Carbonyl and epoxide compounds play crucial roles in organic synthesis, and the utilization of metal catalysis offers distinct advantages. However, the catalysis of their synthesis by high-valent iron-oxo remains a challenge. In this study, we investigated iron-oxo-catalyzed phenyl systems in detail. Our results show that the carbon atoms on the aromatic ring are positively charged by replacing a hydrogen atom with a fluorine atom, which leads to different catalytic mechanisms. Specifically, the cationic intermediate formed via a double-electron transfer in the low-spin (LS) state of a non-fluorinated benzene ring transforms into a radical intermediate via single-electron transfer when fluorine substitution occurs. Further computational investigations revealed that different intermediates in LS drive the formation of different products. The carbocation intermediate strongly favors the generation of carbonyl compounds through the migration of the ipso - hydrogen (known as the "NIH shift"). In contrast, the radical intermediate exhibits kinetic advantages in this pathway, leading to the formation of epoxides. This research provides theoretical support and facilitates the exploration of innovative pathways for carbonyl and epoxide synthesis. Computing was performed via Gaussian 09 software. Geometric optimization, transition state search, and intrinsic reaction coordinate (IRC) analysis were conducted via the hybrid functional B3LYP and the 6-311G(d,p) basis set. Single-point energy calculations were performed via a higher-level basis set, def2-TZVP. Multiwfn 8.0 and VMD 1.9.1 software are utilized for spin density and molecular frontier orbital analysis, as well as for graphically representing key intermediates.

Effects of Exercise Speed and Circle Diameter on Markers of Bone and Joint Health in Juvenile Sheep as an Equine Model

Though circular exercise is commonly used in equestrian disciplines, it may be at the detriment of horses’ musculoskeletal system. To investigate the effects of circular exercise on bone and joint health, 42 lambs were randomly assigned to a non-exercised control, straight-line, small circle, or large circle exercise regime at a slow (1.3 m/s) or fast (2.0 m/s) speed for 12 wk. Blood samples were taken biweekly. Animals were humanely euthanized upon study completion, and the fused third and fourth metacarpals were collected for biomechanical testing and bone density analysis. Fast groups were found to have more bone formation and less resorption activity than slow groups as evidenced by serum biomarker concentrations (p < 0.05). Sheep in the large fast group tended to have greater flexural rigidity and fracture force for the outside leg compared to the inside leg (p < 0.1). Sheep in the small slow group tended to have increased bone mineral density of the outside leg compared to the inside leg, whereas the opposite occurred in the large slow group (p < 0.1). These results provide further evidence for potential asymmetric musculoskeletal adaptations to circular exercise while emphasizing the importance of speed as a positive influence on bone metabolism and strength.

Integrated Geospatial Characterization of Geomorphological and Structural Features in Parts of Enugu, Southeastern Nigeria: Implications for Regional Geology and Land Use

Abstract This study explores the spatial distribution of land cover and geomorphological features in Enugu East, North, and South LGAs, using Land Use/Land Cover (LULC) classification, slope analysis, drainage density, and lineament density. To analyze the current land use patterns, slope characteristics, drainage density, and lineament density in Enugu, and assess their implications for regional urbanisation and environmental management. LULC classification was performed using remote sensing data to categorize land cover into built-up areas, rangelands, water bodies, trees, crops, and other types. Slope analysis categorized terrain into five slope classes. Drainage density was assessed to determine the density of drainage networks. Lineament density analysis identified structural features affecting ground stability. Built-up areas and rangelands dominate the land cover, while agricultural areas are minimal. Slope analysis reveals a predominance of gentle slopes suitable for urbanisation, with smaller areas of steep slopes posing erosion risks. Drainage density varies, with moderate density areas showing suitable conditions for agriculture and urbanisation, and high-density areas prone to erosion and flooding. Lineament density indicates mostly stable ground with high potential for groundwater exploration in fractured regions. The dominance of built-up areas reflects significant urban expansion, while rangelands highlight non-intensive land uses. Steep slopes and high drainage densities present challenges for sustainable urbanisation and require targeted management strategies. Areas with high lineament densities offer potential for groundwater resources but demand careful consideration for construction. The study provides essential insights into land use and geomorphological factors, underscoring the need for integrated planning to balance urban growth with environmental sustainability. Proper management of slope, drainage, and lineament factors is vital for minimizing risks and optimizing land use. This comprehensive analysis integrates multiple geospatial and geomorphological features to offer a holistic understanding of land use dynamics and development constraints in Enugu Local Government Areas (LGAs), providing a basis for informed decision-making in regional planning.

Particle-in-cell simulations of expanding high energy density plasmas with laser ray tracing

The design and analysis of high energy density (HED) laser experiments typically rely on radiation hydrodynamics simulations. However, some laser–plasma interaction regimes are not collisional and cannot be adequately modeled with hydrodynamics. For example, strongly driven magnetic reconnection and magnetized collisionless shock experiments possess extended hydrodynamic or even kinetic properties, necessitating first-principles kinetic simulations. In this paper, we present the benchmarking and first results obtained with a laser-ray-tracing and inverse bremsstrahlung absorption module implemented in the particle-in-cell code PSC. The simulation results are compared to radiation hydrodynamic simulations using the FLASH code as well as analytical estimates. We successfully benchmark the energy deposition model and overall hydrodynamic evolution of the systems. We also consider possible kinetic effects that may be expected from laser-target ablation in the HED regime, including non-local transport and two-temperature effects.

Insights into the exceptional support phase effect on Ag/Sm2Ce2O7: Modulating Ag distribution and Ag-support interaction to construct reactive soot oxidation catalysts

Developing efficient, cost-effective and robust catalysts for soot combustion is crucial yet challenging. In this study, we fabricated Ag-loaded Sm2Ce2O7 paramorphs catalysts (C-type and Cubic fluorite) via different methods, aiming to improve the distribution and interaction of Ag by modifying the crystalline structures of the supports to enhance oxygen activation. The oxygen vacancy concentration and redox performance of the rare earth C-type catalysts exceeded those of the cubic fluorite ones. In the case of the Ag-assisted catalysts, the Sm2Ce2O7–Ag interface with oxygen vacancies displayed an increased affinity for oxygen. The distribution state of Ag on the catalysts is closely related to the Ag–support interactions and the active sites on the support. Experimental analyses and density functional theory (DFT) calculations have revealed a more even dispersion of the Ag species on the C-type catalyst; differential charge density and Bader charge analysis have confirmed that the Ag loadings can alter the surface charge arrangement, resulting in stronger electronic interactions between Ag and the Sm2Ce2O7-C support. Uniformly dispersed Ag species can effectively promote the activation of gaseous O2 molecules, which is key in the oxidation of soot particles. This approach provides a promising strategy for developing more applicable catalysts for soot combustion.

Axisymmetric background-oriented schlieren measurement for cylindrical combustion flow in micro-rocket torches

A high-precision background-oriented schlieren (BOS) measurement technique was developed to analyze the density field of gases ejected from a micro-rocket torch in scramjet combustors. The BOS method was enhanced using an axisymmetric model and inverse Abel transforms, thereby allowing accurate density measurements in complex flow fields and addressing the limitations of traditional BOS applications. Validation tests confirmed the accuracy and stability of the BOS analysis, demonstrating its robustness against experimental noise and reliable density reconstruction. Experiments with varying equivalence ratios revealed significant effects on the ejected gas-density distribution and spread. Under fuel-rich conditions, the combustion temperature and molecular interactions increase, resulting in a lower density and greater jet expansion. This effect produced a clear boundary between the ejected gas and the surrounding atmosphere, whereas lean combustion conditions displayed more diffuse gas boundaries and instability, owing to the lower hydrogen concentration and combustion temperature. These observed behaviors were linked to Lewis number effects, where higher values under fuel-rich conditions enhanced combustion stability and maintained a more defined gas boundary. To further improve the accuracy of the density analysis, this study applied a modified Gladstone–Dale constant based on the in-flame gas composition. The BOS approach was optimized for angled fields of view and extended measurement areas. The results demonstrated that the BOS technique, particularly with the integration of axisymmetric modeling, provides an effective approach for capturing intricate flow structures in combustion, including spatial density gradients along both radial and axial directions.

Trends and Developments in Gamification for Science Education: A Bibliometric Review from 2019 to 2023

This study aims to identify and analyze research trends in gamification focusing on science education and explore opportunities for further development. Using the Systematic Literature Review (SLR) method, a total of 126 relevant publications were identified from the Publish or Perish database indexed by Scopus, with 43 documents from the 2019–2023 period selected and analyzed based on inclusion criteria. These criteria include articles discussing gamification in science education, English-language articles, open-access publications, and Scopus-indexed articles. The literature review process followed PRISMA guidelines to ensure the quality of results, and data were analyzed using bibliometric methods with the assistance of VOSviewer 1.6.20 software. The results indicate significant fluctuations in the number of publications and citations year by year, reflecting the dynamics of research activity. Most publications originate from Spain, the United States, and Malaysia, with quantitative methods being the most widely used approach (51%). The main themes explored include student engagement, motivation, and conceptual understanding, particularly in STEM subjects. Collaborative networks highlight the importance of diverse perspectives in advancing gamification research. Density analysis reveals that the long-term impact and scalability of gamification in educational science still hold substantial potential for exploration. Therefore, further studies are urgently needed to optimize the role of gamification and maximize its benefits in the learning process.

Current source density and functional connectivity extracted from resting-state electroencephalography as biomarkers for chronic low back pain.

Chronic low back pain (CLBP) is a global health issue, and its nonspecific causes make treatment challenging. Understanding the neural mechanisms of CLBP should contribute to developing effective therapies. To compare current source density (CSD) and functional connectivity (FC) extracted from resting electroencephalography (EEG) between patients with CLBP and healthy controls and to examine the correlations between EEG indices and symptoms. Thirty-four patients with CLBP and 34 healthy controls in an open data set were analyzed. Five-minute resting-state closed-eye EEG was acquired using the international 10-20 system. Current source density across frequency bands was calculated using exact low-resolution electromagnetic tomography. Functional connectivity was assessed between 24 cortical regions using lagged linear connectivity. Correlations between pain symptoms and CSD distribution and FC were examined in patients with CLBP. Current source density analysis showed no significant differences between the groups. The CLBP group exhibited significantly reduced FC in the β3 band between the left middle temporal gyrus and the posterior cingulate cortex, and between the ventral medial prefrontal cortex and the left inferior parietal lobule. Prefrontal θ and δ activity positively correlated with pain symptoms. Increased β1 band FC between the right dorsolateral prefrontal cortex and right auditory cortex correlated with greater pain intensity. We found altered neural activity and connectivity in patients with CLBP, particularly in prefrontal and temporal regions. These results suggest potential targets for pain modulation through brain pathways and highlight the value of EEG biomarkers in understanding pain mechanisms and assessing treatment efficacy.

Study on Fluctuating Wind Characteristics and Non-Stationarity at U-Shaped Canyon Bridge Site

To investigate the non-stationary characteristics of the wind field at the U-shaped canyon bridge site and its impact on fluctuating wind characteristics, a wind observation tower was installed near a cable-stayed bridge. The Augmented Dickey–Fuller (ADF) test was employed to assess the stationarity of wind speed series, while the discrete wavelet transform (DWT) was applied to reconstruct the time-varying mean wind and analyze its effect on fluctuating wind characteristics. Results indicate that wind speeds in this region exhibit bimodal distribution characteristics, with the Weibull-Gamma mixed distribution model providing the best fit. The proportion of non-stationary samples increases with height. Autocorrelation function (ACF), partial autocorrelation function (PACF) tests, and power spectral density (PSD) analysis determined the optimal wavelet decomposition level for wind speed in this region. Analysis of non-stationary samples using db10 wavelet reconstruction reveals that the stationary wind speed model overestimates turbulence intensity but underestimates the turbulence integral scale. The downwind spectrum deviates from the Kaimal spectrum in both low- and high-frequency bands, whereas the vertical spectrum aligns well with the Panofsky spectrum. The findings demonstrate that the wavelet reconstruction method more accurately captures fluctuating wind characteristics under the complex terrain conditions of this canyon area.

Analysis of the long-range transport of the volcanic plume from the 2021 Tajogaite/Cumbre Vieja eruption to Europe using TROPOMI and ground-based measurements

Abstract. The eruptions of the Tajogaite volcano on the western flank of the Cumbre Vieja ridge on the island of La Palma between September and December 2021 released large amounts of ash and SO2. Transport and dispersion of the volcanic emissions were monitored by ground-based stations and satellite instruments alike. In particular, the spectrometric fluorescence and Raman lidar for atmospheric moisture sensing (RAMSES) at the Lindenberg Meteorological Observatory measured the plume of the strongest Tajogaite eruption of 22–23 September 2021 over northeastern Germany 4 d later. This study provides an analysis of SO2 vertical column density (VCD) and layer height (LH) measurements of the volcanic plume obtained with Sentinel-5 Precursor/TROPOspheric Monitoring Instrument (TROPOMI), which are compared to the observations at several stations across the Canary Islands. Furthermore, a new modeling approach based on TROPOMI SO2 VCD measurements and the Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) was developed, which confirmed the link between Tajogaite eruptions and Lindenberg measurements. Modeled mean emission height at the volcanic vent is in excellent agreement with co-located TROPOMI SO2 LH and local lidar ash-height measurements. Finally, a comprehensive discussion of the RAMSES measurements is presented. A new retrieval approach has been developed to estimate the microphysical properties of the volcanic aerosol. For the first time, an optical particle model is utilized that assumes an irregular, non-spheroidal shape of the aerosol particles. According to the analysis, the volcanic aerosol consisted solely of fine-mode inorganic, solid, and irregularly shaped particles – the presence of large aerosol particles or wildfire aerosols could be excluded. The particles likely had an isometric to slightly plate-like shape with an effective half of the particle maximum dimension around 0.1 µm and a refractive index of about 1.51. Moreover, mass column values between 70 and 110 mg m−2, mean mass concentrations of 45–70 µg m−3, and mean mass conversion factors between 0.21 and 0.33 g m−2 at 355 nm were retrieved. Possibly RAMSES observed, at least in part, volcanic secondary sulfate aerosol, which was produced by gas-phase homogeneous reactions during the transport of the air masses from La Palma to Lindenberg.

A Deep Learning Approach for the Classification of Fibroglandular Breast Density in Histology Images of Human Breast Tissue

Background: To progress research into the biological mechanisms that link mammographic breast density to breast cancer risk, fibroglandular breast density can be used as a surrogate measure. This study aimed to develop a computational tool to classify fibroglandular breast density in hematoxylin and eosin (H&E)-stained breast tissue sections using deep learning approaches that would assist future mammographic density research. Methods: Four different architectural configurations of transferred MobileNet-v2 convolutional neural networks (CNNs) and four different models of vision transformers were developed and trained on a database of H&E-stained normal human breast tissue sections (965 tissue blocks from 93 patients) that had been manually classified into one of five fibroglandular density classes, with class 1 being very low fibroglandular density and class 5 being very high fibroglandular density. Results: The MobileNet-Arc 1 and ViT model 1 achieved the highest overall F1 scores of 0.93 and 0.94, respectively. Both models exhibited the lowest false positive rate and highest true positive rate in class 5, while the most challenging classification was class 3, where images from classes 2 and 4 were mistakenly classified as class 3. The area under the curves (AUCs) for all classes were higher than 0.98. Conclusions: Both the ViT and MobileNet models showed promising performance in the accurate classification of H&E-stained tissue sections across all five fibroglandular density classes, providing a rapid and easy-to-use computational tool for breast density analysis.

Welch Method and Bootstrapping Applied to Subcritical Gamma Noise

We measured the prompt neutron decay constant α of the CROCUS zero-power reactor at the Swiss Federal Institute of Technology Lausanne using cross-power spectral density (CPSD) analysis of gamma-gamma correlations from two trans-stilbene organic scintillators positioned near the reactor core. We measured critical and subcritical states, with water levels ranging from 960 mm (critical) to 800 mm ( ρ = − 1.4 $ subcritical). Our analysis used the Welch method, dividing signal segments for fast Fourier transform (FFT) frequency analysis and applying bootstrapping uncertainty quantification that uses Welch-defined segments. Results demonstrated a clear increase in the measured α as reactor reactivity decreased, distinguishing critical from subcritical conditions. At the 960-mm critical level, α was estimated at 155.9 ± 0.7 s− 1, and for the 800-mm subcritical level, α increased significantly to 367.3 ± 6.9 s–1. A linear regression of subcritical states yielded a critical estimate of 154.0 ± 3.1 s–1, aligning with the static α estimate at critical. The bootstrapping method produced normally distributed α estimates, confirming data consistency. The gamma CPSD α estimates clearly distinguish reactor states and improve monitoring of zero-power reactors. The future deployment of modular and microreactors as potential candidates for noise analysis is demonstrated in CROCUS, particularly zero-power mock-ups of new designs. The improvement of noise analysis in the subcritical domain from this work will support experimental data for reactor deployment and procedure.

Spatial-Temporal Evolution of Maritime Accident Hot Spots in the East China Sea: A Space-Time Cube Representation

As public concern for maritime safety grows, there is a pressing need to delve deeper into the root causes of maritime accidents and develop effective preventive strategies. Spatial-temporal analysis stands out as a powerful approach to pinpointing accident hot spots. While previous research has shed light on the spatial aspects of these incidents, a comprehensive understanding of their temporal dimensions remains elusive. This paper bridges this gap by leveraging the Space-Time Cube tool in conjunction with traditional Kernel Density analysis to chart the spatial-temporal dynamics of maritime accident hot spots. Focusing on the East China Sea, a region notorious for its high incidence of maritime accidents and home to numerous world-class ports, we present a case study that offers fresh insights. Data spanning from 1994 to 2020, sourced from the Lloyd’s List Intelligence (LLI) database, reveal the evolving landscape of maritime accidents in the area. Notably, since 2005, the Yangtze River Delta Region in China has emerged as a persistent hot spot for accidents, underscoring its significance in maritime safety discourse. Furthermore, our analysis from the 2010s detects a new hot spot expanding towards the southwest of Kaohsiung Port, China, signaling a burgeoning area of concern for maritime safety. While the Fujian coast of China has seen its share of accidents, it is not qualified as a hot spot zone. The Space-Time Cube proves to be an indispensable tool in unraveling the progression of maritime accidents, and our findings indicate that maritime accidents in certain areas may not be merely random occurrences but exhibit intricate patterns.

Characterization of the Trophic State of Rivers’ N'Gotopkré, Anvo, Mouyassué and Toudoum of Aboisso Region (Côte d’Ivoire) from Micro-Algae: Palmer Method (1969)

Aboisso region is known for its high agricultural productivity, its numerous agro-industrial units and its gold panning activities. These sectors of activity could have consequences on water quality, and lead to changes in the composition and structure of micro-algae. This study aims to determine the trophic quality of some rivers in Aboisso region. Campaigns were conducted in four rivers N'Gotopkré, Anvo, Mouyassué and Toudoum. Phytoplankton samples were collected by horizontal traction over 6 m from surface water, using a plankton net with a 20 µm mesh size. The samples were observed using an Olympus CKX 41 optical microscope. Some books were used to identify phytoplankton species. The counting of phytoplankton was carried out using the Malassez cell and the counting unit was the cell. According determination of waters quality, Palmer method was used. A pollution index factor of 1 to 5 was assigned to 20 types of algae most tolerant to organic pollution. The microalgal flora recorded in the rivers consists of 31 taxa and divided into 3 phyla, Chlorophyta, Bacillariophyta and Cyanoprokaryota respectively with 15, 10 and 6 taxa. According to floral diversity, N’Gotopkré and Mouyassué rivers recorded the most taxa respectively with 18 and16 taxa. Analysis of phytoplankton densities indicated a predominance of Chlorophyta with 13.180.103 Cells/L and Mouyassué river with 13.080.103 Cells/L recorded the highest densities. The lowest floristic density was observed in Toudoum river with 740.103 Cells/L. According to the quality of rivers, among the 20 genera presented by Palmer (1969) as bio-indicators of organic pollution, 5 were identified in the rivers. These are the genera Oscillatoria, Scenedesmus, Navicula, Closterium and Pandorina. The different scores ranging from 0 to 13, showed values below organic pollution.

Analysis of Wood Density to Compare the Amount of Accumulated Carbon Dioxide in the Stems of Selected Non-Native Tree Species in Poland

One of the priorities in European policy is the greater use of wood. In this context, it is important to know the total amount of CO2 absorbed by the tree and accumulated in the wood. In the timber industry, butt logs are mainly processed. The aim of this study is to analyze diameter at breast height (DBH), wood density (WD), and the amount of CO2 in grand fir (GF), Douglas fir (DF), northern red oak (NRO), and black locust (BL) wood. The DBH and bark thickness were measured, and cores were taken to study WD and calculate the amount of CO2. Analyses were conducted in three age classes of trees. It was found that in the youngest age class, DF had a significantly larger DBH compared to NRO and BL, and GF had a significantly larger DBH compared to NRO. The wood density of coniferous species was significantly lower compared to broadleaved species. DF absorbed the most CO2. In Class III, DF had significantly larger DBH and significantly lower wood density compared to NRO and BL. DF absorbed significantly more CO2 compared to NRO. In Classes IV and V, DF had larger DBH compared to NRO and lower wood density. The amount of CO2 absorbed by both species was similar. Taking into account the amount of absorbed CO2, the durability of the wood, and aspects related to sustainable forest management of the four studied non-native tree species, Douglas fir seems to be the best choice for cultivation in Polish forests.

Quantitative analysis of peripapillary RNFL capillary density and thickness in patients with mild nonproliferative diabetic retinopathy

PurposeOptical coherence tomography angiography was used to compare the changes of capillary density and thickness of the peripapillary retinal nerve fiber layer in patients with diabetes mellitus (DM) without diabetic retinopathy (DR) and patients with mild nonproliferative diabetic retinopathy (NPDR).MethodsIn this prospective cross-sectional study, 62, 85, and 75 eyes of normal control group (NC), DM group, and NPDR group were included, respectively. All subjects received an optic-disc-centered 6 × 6-mm fundus scan. The annular region outside the optic disc boundary was divided into eight sectors: nasal superior, nasal inferior, inferior nasal (IN), inferior temporal (IT), temporal superior, temporal inferior, superior nasal, and superior temporal (ST). The average retinal nerve fiber layer thickness, average capillary density, and changes in thickness and capillary density of each sector in the annular region were calculated.ResultsCompared with the NC group, the average capillary density of pRNFL in patients with DM and NPDR groups decreased significantly (p < 0.001), and there were significant differences in capillary density in all sectors except the IN sector in the DM group. There was no significant difference in the average thickness of pRNFL between the groups. Only the thickness of ST and IT in DM group and NPDR group, respectively, were significantly lower than that in the control group. In addition, the ROC curve of pRNFL average capillary density has high sensitivity and specificity in distinguishing DR from healthy eyes (AUC = 0.852).ConclusionThe pRNFL average capillary density in diabetic patients without DR and patients with mild NPDR, respectively, were significantly lower than that in healthy controls, especially in the NPDR group.

Non-destructive testing evaluation of stainless-clad steel with imaging inspection

Abstract Due to the dissimilar properties of the cladding layer and carbon steel substrate, which lead to inaccurate inspections, nondestructive testing (NDT) needs to be verified with a reference specimen. This research presented the preparation of stainless-clad steel reference for NDT with imaging inspections such as profile radiography (PRT), ultrasonic phased array (PA), and full matrix capture with the total focusing method (FMC/TFM). The effect of cladding thickness and complex defects on the inspection results was evaluated. In the experiment, the reference specimen was prepared by welding stainless steel on carbon steel and drilling holes to simulate defects as cluster, aligned, and interlayer characteristics. The PRT exhibited asymmetry in two-dimensional images with varying cladding thicknesses, which could be measured by image density analysis but could not identify complex defects. The PA provided images with good accuracy for measuring cladding thickness, but it was limited in detecting some complex defects due to signal reduction. The FMC/TFM demonstrated the best image for thickness measurement and identification of complex defects because its individual element probe could reduce signal intensity loss. In addition, a possible application of FMC/TFM in the butt weld inspection was also demonstrated.