Transition Zone Research Articles

Effect of modifiers on the properties of bamboo scraps/magnesium oxychloride composites under dry-wet cycling environments

Bamboo scraps/magnesium oxychloride composites (BS/MOC) is a new low-carbon and eco-friendly building material, which is composed of magnesium oxychloride cement (MOC) as the matrix and bamboo scraps as the reinforcing materials. However, the poor strength and durability of BS/MOC under special environmental conditions seriously restrict its application range. To solve the above problems, citric acid (CA), D-gluconic acid sodium salt (GS), and styrene-acrylate emulsion (SAE) were used as modifiers to improve BS/MOC properties. The effect of modifier addition on the mechanical strength and durability of BS/MOC was investigated under dry-wet cycling environments. The phase composition, microstructure, pore structure, and Clˉ concentration of BS/MOC were characterized by XRD, TGA, SEM, MIP, and ICS-600. The results showed that CA and GS improved the interface adhesion between bamboo scraps and MOC matrix, and both inhibited the hydration reaction of the residual MgO and the hydrolysis of phase 5 crystals, resulting in good mechanical properties and microstructural stability of BS/MOC under dry-wet cycles. GS outperformed CA in refining pore structure, improving mechanical properties and durability of BS/MOC under identical dry-wet cycles. Conversely, the addition of SAE increased initial defects and interfacial transition zones in the BS/MOC matrix, and increased the total porosity and the harmful pores content, which negatively affected the mechanical properties and durability of BS/MOC.

Morphological and Physico-chemical Properties of Soils of Amtur-3 Micro-Watershed on Schistose Landscape in Bailhongal taluk of Belagavi District, Karnataka, India

Aims: To assess the morphological and physico-chemical properties of two soil series viz., KKT (Kabulayathkatti tanda) and SDH (Singadahalli) of Amtur-3 micro-watershed developed on schistose landscape in northern transition zone of Karnataka. Place and Duration of Study: The study was carried out in the Amtur-3 micro-watershed (4D5B8t04) located in Bailhongal taluk of Belagavi district, Karnataka during 2022-2024. Methodology: Horizon-wise soil samples were collected from the two representative pedons viz., KKT (Kabulayathkatti tanda) and SDH (Singadahalli) soil series, were identified, characterized and classified up to family level according to revisions in Soil Taxonomy using morphological, physical and chemical properties. Results: The soils of these two series were sandy clay loam to clay in texture, neutral in soil reaction and had low salt content. Calcium and magnesium were the dominant cations followed by sodium and potassium. Both the soil series belonged to the order Inceptisol.

Estimation of phloem conductance at tree level in young, middle-aged and old-aged Scots pine trees growing in different climatic conditions in boreal forests.

In forests, a significant proportion of the carbon fixed by trees during photosynthesis is transported belowground along the conducting phloem, so variations in phloem anatomy can lead to variations in transport capacity. Phloem conductance at tree level (Ktree) is also affected by tree height. Both the phloem anatomy and the tree size change during ontogeny, and also differ under different environmental conditions. The goal of our work was to identify the main drivers of variation in Ktree in Scots pine trees growing in natural boreal forests. We conducted a phloem anatomical study and calculated Ktree in trees of three age groups growing in different climatic conditions along a latitudinal gradient from south to north. We found that Ktree was maintained at the same level in actively growing pine trees (25-80-years-old) but increased in old-aged trees (180-190-years-old), possibly reflecting the shift in source-sink relationships of aboveground and belowground parts of trees. Trees of the same age group growing in different climatic conditions demonstrated similar values of Ktree due to coordinated changes in the phloem anatomy and the tree height. In general, the negative influence of tree height on Ktree is offset by the positive influence of phloem width (or trunk diameter) and sieve cell diameter. The exception was young trees growing in the transition zone of the northern taiga subzone to the tundra, where Ktree was the highest in its age group and even exceeded Ktree of middle-aged trees.

Algae promotes the biogenic oxidation of Mn(II) by accelerated extracellular superoxide production

Microbial manganese (Mn) oxidation, predominantly occurs within the anaerobic-aerobic interfaces, plays an important role in environmental pollution remediation. The anaerobic-aerobic transition zones, notably riparian and lakeside zones, are hotspots for algae-bacteria interactions. Here, we adopted a Mn(II)-oxidizing bacterium Pseudomonas sp. QJX-1 to investigate the impact of algae on microbial Mn(II) oxidation and verify the underlying mechanisms. Interestingly, we achieved a remarkable enhancement in bacterial Mn(II)-oxidizing activity within the algae-bacteria co-culture, despite the inability to oxidize Mn(II) for the algae used in this study. In addition, the bacterial density almost remains constant in the presence of algal cells. Therefore, the increased Mn(II) oxidation by QJX-1 in the presence of algae cannot be due to the increased biomass. Within this co-culture system, the Mn(II) oxidation rate surged to an impressive 0.23 mg/L/h, in stark contrast to 0.02 mg/L/h recorded within pure QJX-1 system. The presence of algae could inhibit the Fe-S cluster activity of QJX-1 by the produced active substance in co-culture, and result in the acceleration of extracellular superoxide production due to the impairment of electron transfer functions located in QJX-1 cell membranes. Moreover, elevated peroxidase gene expression and heightened extracellular catalase activity not only expedited Mn(II) ions oxidation but also facilitated conversion of intermediate Mn(III) ions into microbial Mn oxides, achieved through the degradation of hydrogen peroxide. Therefore, the acceleration of extracellular superoxide production and the decomposition of hydrogen peroxide are identified as the principal mechanisms behind the observed enhancement in Mn(II) oxidation within algae-bacteria co-cultures. Our findings highlight the need to consider the effect of algae on microbial Mn(II) oxidation, which plays an important role in the environmental pollution remediation.

Effect of the structure and volume fraction of nanophase on the mechanical properties of (FeNi)86B14 amorphous nanocrystalline alloys

The influence of precipitated nanophases on the mechanical properties of Fe-based amorphous nanocrystalline alloys is an urgent issue to be explored. Two amorphous nanocrystalline alloys, i.e., (Fe0.9Ni0.1)86B14 and (Fe0.7Ni0.3)86B14 containing nanophase of the body-centered cubic and face-centered cubic structures, respectively, were selected to investigate the effect of the structure and volume fraction of nanophase on their mechanical properties. The results of nanoindentation experiments and the calculation of the volume and size of the shear transition zone reveal that the two alloys show different mechanical properties. When the volume fraction of the nanophase in (Fe0.9Ni0.1)86B14 is larger than 50%, the elastic modulus is increased suddenly and the volume and size of the shear transition zone is decreased dramatically, while no dramatic change occurs in (Fe0.7Ni0.3)86B14. Moreover, it was found by using molecular dynamics simulations that the main reason for these abnormal mechanical properties is the change of cluster type in the system due to the incorporation of nanophases with different structures.

Mechanical properties and enhancement mechanism of iron ore tailings as aggregate for manufacturing ultra-high performance geopolymer concrete

Reusing of iron ore tailings (IOT), particularly as recycled aggregate to prepare concrete, plays an important role in reducing dependence on natural resources and solving the problem of waste accumulation. In this paper, the effects of IOT as aggregate on the flowability, compressive strength of ultra-high performance geopolymer concrete (UHPGC) were studied, and the enhancement mechanism of IOT on compressive strength was elucidated through microscopic characterizations. The results show that with the increase of IOT content, the flowability of UHPGC decreases, and the compressive strength increases first and then decreases. 25 % IOT replacement yielded the best compressive strength, and 50 % substitution of IOT was comparable to the without IOT regarding compressive strength. The microstructure analysis shows that the crystalline components in the IOT do not participate in the hydration reaction and have the effect of micro-aggregate filling. The amorphous components on the IOT dissolve rapidly in the early stage, participate in geological polymerization reaction, and produce synergistic effect with slag to promote the formation of hydration products. However, excessive IOT incorporation will inhibit the dissolution of slag active ions and hinder the formation of hydration products. In addition, the enhanced interfacial transition zone (ITZ) and mechanical interlocking effect formed by IOT can effectively inhibit the crack development of UHPGC.

Composition and zoogeography of marine-estuarine fish from a lagoon system in a temperate-tropical transition zone of the Eastern Pacific

We present an updated systematic checklist of fishes from the Bahía Magdalena-Almejas lagoon system (Mexico), including notes on taxonomy, zoogeography, and conservation status, supported by field samplings and the critical review of published and online data. The ichthyofauna is composed by 2 classes, 30 orders, 104 families, 240 genera and 416 species, mainly represented by the class Actinopterygii. Zoogeographically, the fishes showed highest affinity to the San Diego (87.2%), Cortez (81.4%) and Mexican (70%) provinces, reflecting the ancient relationship between the Californian and Tropical Eastern Pacific regions and the existence of a transitional zone in the Baja California Peninsula for fish assemblages from boreal-temperate and warm-tropical derivation, standing out the presence of the endemic Paraclinus magdalenae. The 91% of the ichthyofauna is included by the IUCN Red List as Lower Concern, Data Deficient and Not Evaluated, while Holacanthus clarionensis and Hippocampus ingens, are under Special Protection by the Mexican regulation. Ecologically, 233 species are marine-euryhaline and 177 marine-stenohaline, which preferentially inhabit soft (57%) and rocky (27.5%) bottoms; most species are demersal (60%), benthic (25%) and pelagic (14.4%). The updated checklist could improve the design and implementation of effective fishing regulation strategies and conservation programs for fishes inhabiting this coastal ecosystem.

A Reconstruction of May–June Mean Temperature since 1775 for Conchos River Basin, Chihuahua, Mexico, Using Tree-Ring Width

Currently there are several precipitation reconstructions for northern Mexico; however, there is a lack of temperature reconstructions to understand past climate change, the impact on ecosystems and societies, etc. The central region of Chihuahua is located in a transition zone between the Sierra Madre Occidental and the Great Northern Plain, characterized by extreme temperatures and marked seasonal variability. The objectives of this study were (1) to generate a climatic association between variables from reanalysis models and the earlywood series for the center of Chihuahua, (2) to generate a reconstruction of mean temperature, (3) to determine extreme events, and (4) to identify the influence of ocean–atmosphere phenomena. Chronologies were downloaded from the International Tree-Ring Data Bank and climate information from the NLDAS-2 and ClimateNA reanalysis models. The response function was performed using climate models and regional dendrochronological series. A reconstruction of mean temperature was generated, and extreme periods were identified. The representativeness of the reconstruction was evaluated through spatial correlation, and low-frequency events were determined through multitaper spectral analysis and wavelet analysis. The influence of ocean–atmosphere phenomena on temperature reconstruction was analyzed using Pearson correlation, and the influence of ENSO was examined through wavelet coherence analysis. Highly significant correlations were found for maximum, minimum, and mean temperature, as well as for precipitation and relative humidity, before and after the growth year. However, the seasonal period with the highest correlation was found from May to June for mean temperature, which was used to generate the reconstruction from 1775 to 2022. The most extreme periods were 1775, 1801, 1805, 1860, 1892–1894, 1951, 1953–1954, and 2011–2012. Spectral analysis showed significant frequencies of 56.53 and 2.09 years, and wavelet analysis from 0 to 2 years from 1970 to 1980, from 8 to 11 years from 1890 to 1910, and from 30 to 70 years from 1860 to 2022. A significant association was found with the Multivariate ENSO Index phenomenon (r = 0.40; p = 0.009) and Pacific Decadal Oscillation (r = −0.38; p = 0.000). Regarding the ENSO phenomenon, an antiphase association of r = −0.34; p = 0.000 was found, with significant periods of 1 to 4 years from 1770 to 1800, 1845 to 1850, and 1860 to 1900, with periods of 6 to 10 years from 1875 to 1920, and from 6 to 8 years from 1990 to 2000. This study allowed a reconstruction of mean temperature through reanalysis data, as well as a historical characterization of temperature for central Chihuahua beyond the observed records.

Utilization of recycled fine aggregate in ultra-high performance concrete: Mechanical strength, microstructure and environment impacts

Recycled aggregate derived from construction and demolition (C&D) waste offers new opportunities for the construction industry due to the shortage of natural aggregate. This study presents the feasibility of utilizing recycled fine aggregate (RFA) in ultra-high performance concrete (UHPC) to alleviate autogenous shrinkage, mitigate environmental effects, and further improve mechanical strengths. Three types of RFA with different particle sizes (0–0.6 mm, 0.6–1.18 mm, and 1.18–2.36 mm) are pre-saturated and then used as substitutes for quartz sand in UHPC. The influences of pre-saturated RFA on the workability, internal relative humidity, autogenous shrinkage, compressive strength, resistance to chloride ion penetration, and microstructure of UHPC are investigated. Experimental results showed that, compared to the plain UHPC, incorporation of 20 % RFA with particle size of 1.18–2.36 mm provides efficient internal curing, maintaining a higher internal relative humidity, and thus reducing autogenous shrinkage by 78.5 % at the age of 7 days. The compressive strengths of the UHPC containing 20 % RFA with particle size of 1.18–2.36 mm shows 7.1 % increase at the ages of 28 days. While it has a negligible effect on the fluidity and resistance to chloride penetration. The underlying mechanisms for the enhancement of properties involve the improved hydration degree of UHPC due to internal curing, which optimizes the structure of the interface transition zone and reduces the number of large pores. Furthermore, the sustainability analysis indicated that the use of RFA in UHPC exhibits 7.0 % lower carbon emissions and 7.8 % lower energy consumption, respectively. This study successfully proposes an effective approach for mitigating the autogenous shrinkage of UHPC without sacrificing strengths.

Exploring the Spatiotemporal Evolution Patterns and Determinants of Construction Land in Mianning County on the Eastern Edge of the Qinghai–Tibet Plateau

Studying the spatiotemporal evolution and driving forces behind construction land amidst the intricate ecological and geological setting on the eastern edge of the Qinghai–Tibet Plateau offers invaluable insights for local sustainable development in a landscape transition zone and ecologically fragile area. Using construction land data from four phases, spanning 1990 to 2020, in Mianning County, this study employs methodologies like the Landscape Expansion Index (LEI) and land use transfer matrix to delineate the spatiotemporal evolution characteristics of construction land. A comprehensive set of 12 influencing factors across five categories—geomorphology, geological activity, climate, river and vegetation environment, and social economy—were examined. The Geographically Weighted Regression (GWR) model was then employed to decipher the spatial distribution pattern of construction land in 1990 and 2020, shedding light on the driving mechanisms behind its changes over the three decades. The research reveals distinct patterns of construction land distribution and evolution in Mianning County, shaped by the ecological and geological landscape. Notably, the Anning River wide valley exhibits a concentrated and contiguous development mode, while the Yalong River deep valley showcases a decentralized development pattern, and the Dadu River basin manifests an aggregation development mode centered around high mountain lakes. Over the study period, all three river basins witnessed varying degrees of construction land expansion, transitioning from quantitative expansion to qualitative enhancement. Edge expansion predominantly characterizes the expansion mode, complemented by leapfrog and infilling modes, accompanied by conversions from cropland and forest land to construction land. An analysis of the spatial pattern and drivers of construction land change highlights human-induced factors dominating the Anning River Basin, contrasting with natural factors prevailing in the Yalong River Basin and the Dadu River Basin. Future efforts should prioritize climate change considerations and environmental capacity, aiming for an ecologically resilient spatial pattern of construction land.

Fracture mechanical properties and interfacial characteristics of engineered cementitious composites containing coarse aggregate

Engineered cementitious composites (ECC) have significantly high deformability, but their application in the field of engineered crack prevention is severely limited by their high shrinkage and high cost. To address this issue, a safer and more economical ECC was designed in this paper by adding coarse aggregate (CA) into the ECC matrix (i.e., ECC-CA). Then, experimental studies on the fracture properties of ECC-CA were carried out from both macroscopic and microscopic perspectives, by considering four CA mass contents and three CA particle sizes. The results show that ECC-CA maintains good mechanical properties and deformation capacity as ECC. Its crack mouth opening displacement corresponding to the largest particle size (13–17 mm) and the largest mass content (30 %) is equivalent to 47.8 % of that of ECC, which is about 40 times higher than that of conventional concrete. Further, the interfacial transition zone characteristics between each phase medium and matrix were analyzed in ECC-CA for the purpose of clarifying the crack initiation and evolution trends, elucidating the influence of CA on the fracture mechanism of ECC-CA (i.e., fiber cage effect) based on both macroscopic performance and microscopic characteristics.

Study on the mechanical properties of recycled brick coarse aggregate concrete based on finite element modeling

In recent years, the use of recycled materials in concrete production has garnered significant attention due to their environmental and economic benefits. To promote the application of recycled aggregates, this study focuses on investigating the utilization of Recycled Brick Coarse Aggregate (RBCA) as a substitute for natural aggregate. This paper presents the development of stochastic convex polygonal RBCA through the utilization of a custom-programmed algorithm and proposes a finite element model designed to simulate the behavior of RBCA concrete under compression and splitting tensile. Numerical simulations were conducted to investigate the effects of brick aggregate Replacement Rate (RR) and porosity on the compressive and splitting tensile properties of RBCA concrete. A strong correlation was found between the Concrete Damage Plasticity (CDP) model developed in this study and experimental results, indicating high reliability. The results indicate that the replacement rate of brick aggregates has a more significant impact on the compressive strength than on the splitting tensile strength of concrete. Furthermore, the distribution of coarse aggregates and pores has a minor influence on the mechanical properties and ultimate failure mode of RBCA concrete but significantly affects the crack distribution pattern. The sequence of damage initiation in RBCA concrete was found to be: pores, old Interfacial Transition Zone (ITZ), old mortar, new ITZ, new mortar, RBCA, and Natural Coarse Aggregate (NCA). These findings contribute to a comprehensive understanding of RBCA's performance and offer valuable insights for optimizing its behavior.

Retrospective Study of Multimodality Imaging Features of Chondroblastoma

Abstract Purpose To evaluate the multimodality imaging features of chondroblastoma. Materials and Methods Retrospective analysis of imaging features of 52 cases of histopathologically proven chondroblastoma from 2010 to 2022 was performed. Radiographs were evaluated for lesion site, location, morphology, margins, matrix mineralization, cortical breach, periosteal reaction, eccentricity, and subarticular extension. Appearance on T1, T2 weighted and post-contrast T1 was evaluated on MRI, with analysis of peritumoral edema and joint effusion. Results Mean patient age was 18 years (10–57 years) with male preponderance (M = 39; F = 13). 75% (n = 39) cases involved an unfused skeleton and 25% (n = 13) affected a mature skeleton. Appendicular skeleton was involved in 88.5% (n = 46) cases and axial skeleton was involved in 11.5% (n = 6) cases with all cases involving epiphysis/epiphyseal equivalent. Radiographically, all cases were well-defined geographic osteolytic lesions with a narrow zone of transition, thin sclerotic rim and lobulated [56% (n = 29)] or smooth [44% (n = 23)] margins. Matrix calcification appreciable in 62% (n = 32) cases was ‘fluffy/smudgy’. Chondroblastoma appeared isointense (83%, n = 43) on T1 MRI with characteristically low signal and hyperintense foci within (67%, n = 35) on T2-weighted images and post-contrast enhancement [heterogeneous lobular (88%, n = 46) or septal pattern (12%, n = 6)] with all barring three lesions showing perilesional edema. None of the cases of chondroblastoma in our study developed metastasis till last follow-up (mean: 71 months). Conclusion Chondroblastoma has distinctive imaging appearance and is often unlike majority other cartilaginous benign lesions due to characteristic low T2 signal on MRI and associated exuberant perilesional edema.

Interface reconstruction of MXene-Ti3C2 doped CeO2 nanorods for remarked photocatalytic ammonia synthesis

Prospective photocatalytic ammonia synthesis process has received more attentions but quite challenging with the low visible light utilization and weak N2 molecule absorption ability around the photocatalysts. Herein, interface reconstruction of MXene-Ti3C2/CeO2 composites with high-concentration active sites through the carbon-doped process are presented firstly, and obvious transition zones with the three-phase reaction interface are formed in the as-prepared catalysts. The optimal co-doped sample demonstrates an excellent photo response in the visible light region, the strongest chemisorption activity and the most active sites. Moreover, much more in-situ extra oxygen defects are also produced under light irradiation. It is expected that the double decorated catalyst shows a remarked ammonia production rate of above 0.76 mmol gcal−1·h−1 under visible-light illumination and a higher apparent quantum efficiency of 1.08 % at 420 nm, which is one of the most completive properties for the photocatalytic N2 fixation at present.

Ultrasonic wave characteristics in multiscale cementitious materials at different stages of hydration

Monitoring the microstructural change in cementitious materials during hydration is an essential but challenging task. Therefore, a non-invasive and sophisticated technique is warranted to understand the microscopic behaviour of the multiphase cementitious materials (where the length scale of the constituents varies from centimeters to micrometers) in different stages of hydration. Due to exothermic hydration reactions, different hydration products start to evolve with individual mechanical properties. In concrete, an interface transition zone (ITZ) appears between the aggregate surface and paste matrix, which influences the overall properties of concrete material. In the present research, 1) several wave characteristics, such as wave velocity, energy distribution, and signal phase are found out using Ultrasonic Pulse Velocity (UPV), Wavelet Packet Energy (WPE) and Hilbert Transform (HT) methods, to monitor the hydration mechanism (1d-28d) in cement-based materials with two levels of heterogeneities (cement paste and concrete, representing microscale and mesoscale, respectively). Also, the unique nonlinear behaviour is studied in the frequency domain using the promising Sideband Energy Ratio (SER) and Sideband Peak Count Index (SPC-I) methods. 2) Numerical simulations are carried out to understand the wave interaction in the developing microstructure. A discretized microstructure of cement shows microscopic details of each phase at any instant of hydration (e.g., formation stage and after complete maturity level). The experimental and numerical investigations on the characteristics of the nonlinear ultrasonic wave propagation show the impact of microstructural development of multi-scale cementitious materials during hydration.

Spatiotemporal Evolution and Coupling Analysis of Human Footprints and Habitat Quality: Evidence of 21 Consecutive Years in China

Assessing the spatiotemporal evolution characteristics of habitat quality, human footprint, and coupling coordination between two systems in continuous cycles and on national scales is of great significance to maintaining biodiversity and sustainable development. This study took China as an example, based on land-use data from 2000 to 2020, using the Integrated Valuation of Ecosystem Services and Tradeoffs—Habitat Quality (InVEST-HQ) model and the human footprint framework, coupling trend analysis methods such as Theil–Sen Median Analysis, Mann–Kendall Test, and Grid Transition Matrix (GTM) Method and combining the four-quadrant model and the coupling coordination degree model (CCDM) to reveal the spatiotemporal evolution characteristics of habitat quality, human footprint, and CCDM in China for 21 consecutive years and the response relationship between the two systems of habitat quality and human footprint. The results show that the land cover change area from 2000 to 2020 accounted for 4.2% of the total area. Both habitat quality and human footprints exhibit apparent spatial heterogeneity along the “Hu Line” and generally fall into two evolutionary stages: “degradation–improvement”. The proportions of degradation and improvement were 14.37% and 8.36%, respectively, and the mutation point was in the year 2013; the average human footprint increased by 16.75%, and the increased and decreased area proportions were 63.40% and 21.53%, respectively. The mutation occurred in 2014. The right side of the “Hu Line” primarily hosts areas with high values of the coordinated coupling index of human footprints and habitat quality systems. The four quadrants generally have the following characteristics: “quadrant IV on the right is dominant, quadrants II and III on the left are dominant, and quadrant I is located in the transition zone of the ‘Hu Line’”. The coupling coordination degree (CCD) and human footprints have a weak, nonlinear “inverted U-shaped” relationship. This study provides compelling evidence for the spatiotemporal evolution and coupling relationship between habitat quality and human footprint in China, provides scientific decision-making support for biodiversity protection and sustainable economic development, and maintains the bottom line of ecological security for a beautiful China.

Measurement of T1ρ dispersion with compressed sensing and magnetization prepared radial balanced steady-state free precessionin spontaneous human osteoarthritis.

To assess the potential for accelerating continuous-wave (CW) T1ρ dispersion measurement with compressed sensing approach via studying the effect that the data reduction has on the ability to detect differences between intact and degenerated articular cartilage with different spin-lock amplitudes and to assess quantitative bias due to acceleration. Osteochondral plugs (n = 27, 4 mm diameter) from femur (n = 14) and tibia (n = 13) regions from human cadaver knee joints were obtained from commercial biobank (Science Care, USA) under Ethical permission 134/2015. MRI of specimens was performed at 9.4T with magnetization prepared radial balanced SSFP (bSSFP) readout sequence, and the CWT1ρ relaxation time maps were computed from the measured data. The relaxation time maps were evaluated in the cartilage zones for different acceleration factors. For reference, Osteoarthritis Research Society International (OARSI) grading and biomechanical measurements were performed and correlated with the MRI findings. Four-fold acceleration of CWT1ρ dispersion measurement by compressed sensing approach was feasible without meaningful loss in the sensitivity to osteoarthritic (OA) changes within the articular cartilage. Differences were significant between intact and OA groups in the superficial and transitional zones, and CWT1ρ correlated moderately with the reference measurements (0.3 < r < 0.7). CWT1ρ was able to differentiate between intact and OA cartilage even with four-fold acceleration. This indicates that acceleration of CWT1ρ dispersion measurement by compressed sensing approach is feasible with negligible loss in the sensitivity to osteoarthritic changes in articular cartilage.

Chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion stability of interfacial transition zone material using alkali-treated banana fiber for concrete

ABSTRACT It might be of interest for authors to learn more that in the early 1900s, fibers were used in cement-based material, as cement-based materials exhibit shrinkage cracking over time, which can be controlled by adding fibers. The main aim of the inserting natural fiber into cement-based material is to decrease the shrinkage of cement-based material, prevent the rising of shrinkage cracks, and develop low-cracking cement-based material. In the research, the same aim aforementioned was kept same way. For carrying out the aim, agricultural waste, known as banana fiber (BF), can be considered a shrinkage reducer, expansion stabilization, a renewable material and has potential to make cement-based material transformed into a green construction material. This research investigated the effect of BF incorporation on cement paste shrinkage. Thus, five mixes were developed with different BF additions based on the total volume of cement paste (0, 0.5, 1, 1.5 and 2%). For each mixture, four tests were carried out to assess the impact of BF addition on the paste’s volume stability: chemical, autogenous, drying shrinkage and expansion. Testing was conducted for up to 90 days. Compared to the control mix, the addition of 2% BF reduced chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion by 27%, 57%, 47%, and 66%, respectively. Furthermore, a positive correlation was observed between chemical shrinkage and both autogenous and drying shrinkage and the percentage of BF content. Conversely, there was an inverse relationship between chemical shrinkage and expansion. The most significant conclusion to emerge from this study is that the incorporation of banana fiber (BF) into alkali-treated concrete results in a reduction in chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion. This is attributed to the molecular structure of BF, which is characterized by uninterrupted glycosidic linkages, leading to alkaline breakdown within the alkaline environment. Consequently, the alkali-treated BF can be described as a volume stability admixture in concrete technology.

High-fidelity simulations of boundary layer transition on an underwater axisymmetric body with stability theory

During the cruise status of an underwater high-speed vehicle, the flow around the vehicle's head typically transitions from a laminar to a turbulent state, triggering flow noise that can interfere with the normal operation of sonar. In order to accurately investigate this flow noise through numerical simulation, a high-fidelity turbulent flow field solution is essential. Common traditional turbulence numerical simulation methods, such as unsteady Reynolds-averaged simulation and large eddy simulation (LES), struggle to capture high-frequency turbulent fluctuations accurately due to their inability to directly resolve small-scale eddy structures, which results in compromising the simulation accuracy of high-frequency flow noise. To address this issue, this paper employs direct numerical simulation (DNS) to achieve high-fidelity resolution of the turbulent flow field, thereby enabling a more accurate assessment of flow noise distribution on the vehicle's surface. Meanwhile, considering significant computational resources required to solve the entire flow field in an underwater high Reynolds number environment, this study also incorporates the fixed transition modeling method and stability theory to confine the DNS computational domain to the vicinity of the transitional zone to improve simulation efficiency. Comparative analysis of flow noise monitoring results in the laminar, transitional, and turbulent zones revealed that the flow noise source in the laminar zone exhibits the lowest amplitude across all frequencies, while the flow noise source in the transitional zone features the highest amplitude, approximately 10 dB higher than that in the turbulent zone. Moreover, significant amplitudes in high-frequency components (above 30 kHz) are detected in both the transition and turbulent zones. Additionally, this study employs LES with the Smagorinsky model to simulate the flow field within the same computational domain as DNS, demonstrating the limitations of the Smagorinsky model-based LES in capturing high-frequency flow noise.

Evaluation of large-scale deforestation susceptibility mapping in the mountainous region of the Himalayas: A case study of the Khangchendzonga Biosphere Reserve, India

The Khangchendzonga Biosphere Reserve (KBR) is located in the Eastern Himalayas and serves as a critical habitat for endemic species of flora and fauna, as well as playing a key role in carbon sequestration. The primary aim of this study was to map large-scale deforestation susceptibility zones in the mountainous region of KBR. The study area was divided into three zones: (a) Transition Zone, (b) Core Zone, and (c) Buffer Zone. This study utilized multiple remote sensing datasets acquired through the Google Earth Engine (GEE) platform, including precipitation, temperature, elevation, forest density, distance from rivers, NDVI, NDSI, distance from settlements, settlement density, distance from roads, and land use and land cover data. Additionally, the Analytical Hierarchy Process (AHP) and Simple Additive Weighting (SAW) methods were employed to map deforestation susceptibility. To validate the proposed deforestation susceptibility, Hansen Global Forest Change (HGFC) data from 2001 to 2022 were used. Moreover, deforestation susceptibility was evaluated using the Receiver Operating Characteristic (ROC) curve and the Area Under the Curve (AUC) metrics. Notably, our findings revealed significant declines in tree cover of 1.60%, 1.27%, and 0.89% in the Transition, Core, and Buffer Zones, respectively, during critical years (2009, 2011, 2019, 2020). These periods witnessed substantial deforestation, indicating a deteriorating condition of the reserve's forest cover. Although there were minor discrepancies in the results of the two methods, both highlighted the particular vulnerability of the transition zones in the eastern and southern regions of KBR. The comprehensive methodology employed in this research establishes an advanced spatial data infrastructure that is indispensable for immediate conservation planning and adaptive management strategies. The insights gleaned from this investigation hold substantial promise for guiding future restoration and conservation efforts aimed at enriching biodiversity and fortifying ecosystem services in this critical area.