Search Results (16,748)

This study evaluated the use of visible and near-infrared (Vis-NIR) spectroscopy combined with machine learning (ML) algorithms to predict soil fertility-related properties in two contrasting agroecological regions of Peru: the Highlands and the Rainforest. A total of 297 soil samples were analyzed using portable spectroradiometers covering a spectral range of 350–2500 nm, applying transformations such as Savitzky–Golay smoothing, first derivative, and band depth. Predictive models were developed using PLSR, Random Forest, Support Vector Machines, and neural networks. Results show variable predictive performance across soil properties and ecosystems. Organic matter in Highland soils and calcium in Rainforest soils achieved the strongest test-set accuracy (R² > 0.70), while pH and texture fractions showed moderate performance (R² = 0.42–0.67), and mobile nutrients including phosphorus, potassium, and sodium showed limited predictive accuracy due to their weak spectral expression. Spectral predictions were further integrated into a structured nutrient balance framework to assess agronomic reliability. Nitrogen fertilizer recommendations showed the strongest agreement between observed and predicted values across both ecosystems, whereas K₂O and CaO recommendations in Highland soils were substantially underestimated, demonstrating that property-level statistical performance does not guarantee agronomic reliability. These findings confirm that Vis-NIR spectroscopy combined with ML represents a fast, cost-effective, and sustainable alternative to conventional soil analysis, especially in rural areas with limited laboratory infrastructure. Expanding regional calibration datasets and exploring mid-infrared FTIR spectroscopy as a complementary technology are identified as priority directions for improving predictions of agronomically critical nutrients. Full article

This study investigates the macro–meso shear characteristics of the geogrid–silty clay interface under cyclic loading through a combination of laboratory cyclic direct shear tests and numerical simulations. The effects of geogrid roughness, soil moisture content, shear displacement amplitude, and normal stress on the interface behavior are systematically analyzed. The results show that the interface shear strength and shear stiffness exhibit a three-stage evolution with increasing cycle numbers. This evolution is characterized by rapid attenuation in the early stage, gradual change in the middle stage, and stabilization in the later stage. The main degradation occurs within the first 1–10 cycles, while the interface response tends to stabilize after approximately 25 cycles. Increasing geogrid roughness and normal stress significantly enhances the interface shear strength and restrains cyclic degradation. In contrast, the shear strength reaches a maximum at the optimum moisture content level of 13%. The damping ratio shows an opposite trend to stiffness, increasing with cycle number and gradually approaching stability. Numerical simulation results are in good agreement with the experimental data, with relative errors within 5%. At the mesoscopic level, shear stress is mainly concentrated at the intersections of geogrid ribs, and the soil zone within 0–20 mm above the interface is identified as the primary region of shear deformation. Full article

This research was motivated by the urgent need to address resource shortages and high energy costs in concrete production by replacing an energy-intensive traditional curing method with a new, more sustainable solution. By exploring solar heat treatment with composite binders and THACs, the study aimed to develop sustainable, cost-effective alternatives that harness renewable energy sources and optimize natural cement hydration processes for accelerated hardening. This article explores the potential application of solar energy in the production of precast concrete products using a composite binder. The effectiveness of the composite binder in solar thermal treatment of concrete using translucent heat-accumulating coatings is tested. The results of laboratory studies are presented, and the feasibility of using concrete based on composite binder at the laboratory scale for the production of concrete and reinforced concrete products, both with steaming and with solar thermal treatment, is established. The study of the structural features and basic physical and mechanical properties of hardened concrete under various conditions indicates that, under the investigated laboratory conditions, solar-thermally treated concrete exhibits physical and mechanical properties comparable to those of normally cured concrete. Laboratory studies confirmed the effectiveness of both steaming and solar heat treatment methods under controlled experimental conditions. Within the scope of the performed laboratory tests, the structure and properties of these concretes were comparable to those of normally cured concretes and, in several aspects, superior to those obtained under conventional steam curing regimes, which indicates the effectiveness of the described method, not only from the point of view of significant savings in fuel and energy resources. When producing products based on composite binders using solar thermal treatment, the consumption of the clinker portion of the binder is reduced by 50% (composition of the composite binder itself) and the consumption of conventional fuel during heat and moisture treatment is reduced by 70–100 kg per 1 m³ of concrete (reflecting process-level comparisons), which is of significant value for external energy demand. These findings confirm the technical feasibility and environmental advantages of the proposed method at the laboratory scale and highlight its potential for broader industrial application in precast concrete production. Full article

Tuberculosis (TB) remains a leading cause of morbidity and mortality worldwide, with children representing a particularly vulnerable population in whom diagnosis is often challenging. Pediatric TB is typically paucibacillary and presents with non-specific clinical manifestations, limiting the sensitivity of microbiological confirmation and increasing reliance on immunological tests. The Tuberculin Skin Test (TST) and Interferon-Gamma Release Assays (IGRAs) are the most widely used tools for detecting Mycobacterium tuberculosis infection, yet both have important limitations, especially in young children and in Bacillus Calmette–Guérin (BCG)-vaccinated populations. TST lacks specificity due to cross-reactivity with BCG and environmental mycobacteria, while IGRAs, although more specific, require laboratory infrastructure and may have reduced sensitivity in early childhood. The Tuberculosis Skin Test (TBST), based on M. tuberculosis-specific antigens such as ESAT-6 and CFP-10, has emerged as a promising alternative that combines the operational simplicity of TST with the antigenic specificity of IGRA. This paper reviews the immunological principles, diagnostic performance, and practical considerations of TBST in pediatric populations, with direct comparison to TST and IGRA. Evidence from recent studies suggests that TBST may offer improved specificity over TST, with broadly comparable diagnostic accuracy to IGRA in some settings, although findings are not fully consistent across studies. Particular attention is given to its performance in BCG-vaccinated children and, based on emerging evidence, in those under five years of age. The potential role of TBST in clinical algorithms and public health strategies is discussed, along with current evidence gaps and future research priorities. Full article

Tailings are unconventional geomaterials that require dynamic characterisation due to seismic hazards at several storage facilities. Due to the anthropic origin of these materials, their dynamic properties differ from those reported for natural soils. In particular, the damping ratio is a relevant parameter that controls the dynamic response of tailings storage facilities. It can be estimated using different experimental methods. The objective of this research is to disclose the results obtained through laboratory tests in which the damping ratio was evaluated independently by Half-Power Bandwidth or the free-vibration decay methods. A comprehensive testing plan comprising resonant column tests and free-vibration decay tests was carried out on three types of tailings from the Riotinto mines (Huelva, Spain): Cerro Salomón Sand (CSS), High-Density Sludge (HDS), and Copper Lamas (CL). These tests were carried out under different effective consolidation pressures and torsional excitations. The results allowed the establishment of a series of relationships between the testing conditions and the identification of differences between the methods for tailings. Full article

The UK telecommunications sector’s 5G rollout is projected to consume 2.1% of national electricity by 2030, raising urgent sustainability concerns. This study empirically investigates, under controlled laboratory conditions, the energy performance and cost characteristics of two private 5G architectures—Vodafone’s Mobile Private Network (MPN) and an Open Radio Access Network (O-RAN) via BubbleRAN—and contextualises them against public network references and the United Nations Sustainable Development Goals (SDGs). Two complementary dimensions of energy performance are assessed: absolute power consumption (Watts), reflecting total system draw regardless of throughput; and throughput efficiency (Mbps/W), capturing useful data delivered per unit of energy. In terms of absolute power, O-RAN consumes less (460 W active, 378 W idle) than MPN (645 W active, 620 W idle). In terms of throughput efficiency, MPN delivers 1.45 Mbps/W versus O-RAN’s 0.44 Mbps/W under these specific controlled, single-cell conditions, a difference that reflects the tested hardware configurations (n77 vs. n78 band; 936 Mbps vs. 202 Mbps throughput; 2 × 2 vs. 4 × 4 MIMO) as much as any intrinsic architectural distinction. Both architectures offer substantially lower annual energy costs (£1060–£1486) compared to public micro-cells (£1991–£2666), representing 44–60% savings. Session continuity was 100% across all controlled trials; this reflects short-term laboratory conditions and should not be extrapolated to a long-term network availability guarantee without extended field validation. These results are configuration-specific preliminary indicators; the relative efficiency advantage of each architecture is expected to vary with load, band, and deployment scale. By 2030, UK 5G network operations are projected to generate 795,347–1,260,532 tonnes of CO₂ annually across low-to-high demand scenarios; private deployment, by reducing site proliferation 15–33%, could displace a meaningful share of this footprint. These findings support SDGs 4, 8, 9, 12, and 13. Hybrid O-RAN–MPN pilots are recommended to maximise sustainability gains while advancing social equity and net-zero targets. Full article

Tunnels excavated in non-coal oil- and gas-bearing strata may experience the seepage and intermittent ingress of an oil–gas–water mixture during construction, creating aggressive corrosive conditions that can compromise the integrity of primary support and the safety margin of the final lining. However, the coupled degradation mechanism of primary support and its cascading effect on lining safety under such conditions remain poorly understood. Based on the Huaying Mountain Tunnel project, this study investigates the corrosion-driven damage evolution of primary support and its implications for the structural safety of the secondary lining under wet–dry cycling exposure. Accelerated wet–dry cycling tests were performed on concrete specimens using an on-site crude-oil–formation-water mixture collected during tunnelling, with exposure levels ranging from 0 to 120 cycles. Laboratory observations were then combined with inverse identification of degradation-dependent material parameters to establish a corrosion-informed mechanical description, which was implemented in numerical simulations for structural response assessment. Results show a staged evolution of mechanical properties, with an initial increase followed by progressive deterioration. After 120 cycles, compressive strength, tensile strength, and elastic modulus decreased by approximately 18.9%, 23.1%, and 17.4%, respectively. Degradation is more pronounced in the corroded zone, with tensile capacity and stiffness deteriorating earlier than compressive resistance. Numerical results indicate that corrosion leads to significant stress redistribution and damage development. The sidewall tensile stress reaches 2.80 MPa after 120 cycles, exceeding the post-corrosion capacity, while the safety factor drops below the code threshold at 90 cycles. The overall safety probability decreases from 1.0 to 0.4, accompanied by a degradation in safety grade from Level I to Level IV. These findings provide a quantitative basis for deterioration assessment, safety verification, and maintenance planning for tunnels subjected to oil–gas corrosive environments. Full article

Cement stabilized macadam (CSM) bases are prone to cracking and void damage under long-term traffic loading and environmental actions, which accelerates structural deterioration. Although grouting is an effective method for treating such concealed defects, laboratory-based evaluation of repair effectiveness remains limited. In this study, field-cored CSM specimens were recombined in a cylindrical mold to simulate four void conditions (1/4, 2/4, 3/4, and 4/4), and repaired using an inorganic cementitious composite grouting material based on ultra-fine cement and high-belite sulphoaluminate cement (HBSAC), and modified with ethylene-vinyl acetate (EVA) latex, wollastonite (WO) whiskers, and polyvinyl alcohol (PVA) fibers. The repair effectiveness was evaluated through ultrasonic testing, capacitance measurement, uniaxial compression with acoustic emission (AE) monitoring, and computed tomography (CT). The results show that the longitudinal wave velocity of all repaired groups increases continuously with curing time, with a maximum increase of 21.98% at 28 days. The normalized capacitance response exhibits clear time- and layer-dependent variation, with the 4/4 group showing the most pronounced spatial heterogeneity. In the uniaxial compression tests, the peak load increases from 181 kN in the control group to 201–286 kN in the repaired groups, while the tensile-related AE event proportion increases from 77.35% in the 1/4 group to 89.38% in the 4/4 group. CT analysis shows that the proportion of micropores smaller than 1 mm³ increases from 66.3% to 82.7%, whereas the proportion of pores larger than 100 mm³ decreases from 46.5% to 21.6% after repair. These results demonstrate that the composite grouting material provides effective filling, structural reconstruction, and mechanical enhancement for void-damaged CSM, and that the proposed multi-source characterization framework is suitable for evaluating grouting repair performance. Full article

Understanding how land management influences soil carbon (C) and nitrogen (N) dynamics is critical for improving ecosystem resilience and carbon sequestration potential in semiarid rangelands. This study used classical field- and laboratory-based methods to assess soil organic carbon (SOC), organic matter (OM), and N content at 13 sites across four ecological provinces in eastern Oregon, USA. Treated sites—where traditional rangeland restoration and management practices had been applied to them (i.e., juniper removal, sagebrush removal, post-fire grass seeding, and land conversion to pasture)—were paired with adjacent untreated control sites. Soil samples were collected at two depths, 0 to 10 cm and 15 to 25 cm and analyzed for C, N, OM, bulk density (BD), soil volumetric water content (SVWC), porosity, and texture. Soil C and N stocks were calculated on an area basis (t ha⁻¹), and statistical analyses were conducted using one-way ANOVA and correlation tests. Treated sites generally exhibited higher soil C, N, and OM content compared to untreated sites, particularly in the upper 10 cm of soil. Data obtained from the two soil depths (0 to 10 cm and 15 to 25 cm) were averaged and assumed to represent the top 30 cm of the soil profile, corresponding to the effective rooting zone at each field. The site where sagebrush removal was followed by grass seeding exhibited the highest soil C and N stocks (115.8 t C ha⁻¹ and 9.2 t N ha⁻¹, respectively). This site also had the highest OM content (9.53%), which was observed in the topsoil layer (0 to 10 cm) across all sites and depths. Strong positive correlations between C and N were detected across all sites (mean r = 0.92), while negative correlations were observed between soil C and bulk density at several locations. Results suggest that vegetation management practices such as woody plant removal and grass establishment can enhance soil C storage and nutrient retention in semiarid rangeland ecosystems. These findings provide baseline data to inform land management strategies aimed at improving soil health and carbon sequestration potential in the Pacific Northwest region in the USA. Full article

Knowledge about the condition of electrical equipment in energy networks is of great importance to network operators. Partial discharges are a key parameter for evaluating the health of the insulation. While a quantifiable PD measurement for offline tests is state of the art, it is costly and labour-intensive. It, therefore, makes sense to carry out permanent monitoring during operation. At the medium-voltage level in the European interconnected grid, comprehensive monitoring of PD is not implemented. This study presents a novel sensor concept that is used to detect PD in medium-voltage switchgear and cables: the so-called Magnetic Flux Concentrator Sensor (MFCS). It is an inductive sensor concept with high sensitivity in the frequency range of a few MHz, like well-established High-Frequency Current Transformers (HFCTs) but with better magnetic saturation properties in specific use cases. The highly permeable ferrite core of the MFCS is unconventionally shaped, resulting in a higher-saturation field strength. Therefore, this sensor is not driven into saturation by the operating currents of typical MV power cables. Using the MFCS and conventional HFCT in a suitable combination enables direction-selective PD detection. This work presents the sensor concept and the method for directional detection of the PD location, as analysed and evaluated theoretically and practically with laboratory experiments. Full article

Background/Objectives: This study aimed to evaluate the differences between two blood product transfusion protocols [a standard coagulation (SC) group and a rotational thromboelastometry (ROTEM) group] in patients with decompensated liver cirrhosis (LC) undergoing high-bleeding-risk endoscopic procedures. Methods: Between December 2024 and March 2025, we conducted a prospective cohort study including adult decompensated cirrhotic patients who needed prophylactic blood product transfusion before high-bleeding-risk endoscopic procedures. The prophylactic blood product transfusion strategy in the SC group was based on conventional coagulation tests (INR, platelets, and fibrinogen), and in the ROTEM group on viscoelastic parameters. Results: A total of 72 patients were included in this study (36 patients in each group); most were male (63.9%), Child–Pugh B (54.2%), and had LC with a predominance of alcoholic etiology (51.4%). There were no clinically significant differences regarding the baseline characteristics between the study groups. The most frequent endoscopic procedure was polypectomy (76.4%). Postinterventional bleeding occurred after eight procedures in the SC group and after four procedures in the ROTEM group (p = 0.206). Endoscopic hemostasis was effective. Patients from the ROTEM group received fewer FFP transfusions than the SC group (5.6% vs. 69.4%; p < 0.0001). Blood product transfusion was needed less in patients evaluated using ROTEM compared with the SC group (41.2% vs. 100%; p < 0.0001). There were no differences in the length of hospital stay (p = 0.618) or 30-day mortality (p = 0.643) between the two study groups. Conclusions: ROTEM-guided transfusion management was associated with a significant reduction in blood product use compared with standard coagulation test-based management. However, this difference should be interpreted in the context of the distinct transfusion thresholds applied in the two groups, as the standard coagulation arm followed predefined laboratory-based criteria that may have increased the likelihood of prophylactic transfusion. No statistically significant differences were observed in bleeding complications, length of hospital stay, or 30-day mortality. Therefore, these findings reflect differences in transfusion strategies rather than demonstrating clinical superiority of ROTEM-based management and should be considered preliminary. Full article

Azo dyes demonstrate dose-dependent carcinogenic and mutagenic effects in exposed cells. Among remediation approaches, microbial adsorption is the most sustainable and environmentally friendly method for eliminating azo dyes. A novel Aspergillus terreus silica composite was developed as a sustainable adsorbent for crystal violet dye (CVD) removal. The fungal strain was isolated from dye wastewater and was genetically identified by 18S rRNA gene sequencing. Dried mycelia of A. terreus (PX920301) were combined with SiO₂ (1:1 w/w) through iterative hydration-drying cycles, yielding a composite characterized by FTIR analyses. Removal CVD %, adsorption capacity, and CVD residual were calculated, and the adsorption process was optimized using Box–Behnken design (four factors, 25 runs). The biosafety of the composite was assessed for phytotoxicity and microbial toxicity. The composite was also applied to real dyes wastewater collected from the bacteriological laboratory. Aspergillus terreus-silica composite showed the highest CVD removal percentage by 85.4%, adsorption capacity (qe) 121.1 mg/L, and lowest CVD residual by 7.26 mg/L, followed by the dried active mycelia (DA-mycelia) with CVD removal 40.23%, adsorption capacity (qe) 57.05 mg/L, and CVD residual by 29.73 mg/L. Optimization data cleared that the maximum experimental values of CVD removal (%) was 99.59% (predicted value 100%) obtained in run number (4) using initial CVD concentration (200 mg/L), pH (8), adsorbent composite weight (0.1 g), and contact time (48 h). Biosafety evaluation demonstrated negligible phytotoxicity against Triticum aestivum seedlings post-treatment, with restored germination and growth comparable to controls. Microbial toxicity assays via well-diffusion to seven microbial isolates confirmed no toxic activities against the tested bacteria, yeast, and fungi, underscoring the composite’s environmental safety. The composite could decolorize the real dye wastewater of laboratories by 95.37%. In conclusion, A. terreus mycelial-silica composite offers a cost-effective, sustainable, and eco-friendly alternative solution for dye bioremediation. Full article

The disposal of waste tyres presents a significant environmental challenge, necessitating sustainable, high-value recycling solutions. This study explores the incorporation of waste tyre metal fibre (WTMF) into hot mix asphalt (HMA) to enhance mechanical performance while reducing its electrical resistivity as well as the landfill burden. The primary goal of this research is to apply response surface methodology (RSM) to experimental data for modelling and optimizing WTMF-modified HMA mixes by capturing the coupled effects of fibre reinforcement and binder content on mechanical and functional performance. The microstructural characteristics of WTMF were examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). WTMF-modified mixes containing five WTMF dosages (from 0% to 1.50%) and bitumen contents from 4% to 6% were prepared and tested in the laboratory. The resulting dataset was used for RSM modelling, with WTMF and bitumen contents as input factors and Marshall stability, flow, porosity, and electrical resistivity as response variables. The central composite design (CCD) technique was employed to quantify interaction effects and to identify statistically significant trends. The developed models were validated using statistical indicators, and optimal mixture compositions were determined and experimentally verified. Microstructural analysis revealed WTMF’s irregular, rough surface with microcracks and pits, aiding crack-bridging and stress transfer. RSM results indicated 0.71% WTMF and 5.1% bitumen as an optimal combination of factors. Furthermore, high R² (>0.80) and adequate precision (>4.0) values from analysis of variance (ANOVA) underscore the significance of the proposed models, revealing a robust correlation between experimental and predicted data. This study demonstrated WTMF’s potential to be used in conventional HMA mixes, offering a sustainable recycling pathway for waste tyres. Full article

Surface roughness is a key tribological property commonly characterized by the power spectral density (PSD) of surface topography. However, the recent Surface Topography Challenge demonstrated that measurements of identical surfaces may yield PSD curves differing by several orders of magnitude depending on the laboratory and measurement method. Such discrepancies can arise from measurement artifacts, including spike-like outliers and macroscopic surface curvature. In this work, we analyze these effects and propose a correction procedure for recovering the intrinsic roughness spectrum. The method combines nonlinear median filtering for artifact detection with robust PSD reconstruction based on multiple one-dimensional surface sections. Outliers are removed in real space, the macroscopic shape is eliminated by detrending, and the PSD is obtained as the median of spectra from individual line scans. Tests on synthetic surfaces with known roughness spectra contaminated by curvature and artificial spikes demonstrate that the method reliably recovers the original spectrum even when artifacts dominate the raw data. Application to experimentally measured surfaces further indicates that some apparent roughness features may originate from measurement noise and stitching artifacts rather than the true surface structure. Full article

Prestressed concrete railway sleepers are key structural components that determine the safety, durability, and serviceability of modern railway infrastructure. This study presents a comprehensive investigation of the design, testing, and acceptance of prestressed concrete sleepers in accordance with EN 13230, with particular reference to the requirements applied on the Polish railway network. The analysis integrates normative provisions, analytical calculations, finite element modeling, and experimental verification, including static, dynamic, and fatigue load tests. Special attention is given to the k_t coefficient, which accounts for prestress losses, fatigue degradation, and the development of concrete strength throughout the service life. This coefficient plays a critical role in the acceptance criteria for sleepers during mandatory product testing. The influence of concrete age on the variability of k_t is examined, showing that the highest variability occurs within the first 180 days of curing. Full-scale laboratory tests performed on PS-94 sleepers confirm compliance with standard requirements regarding cracking loads, crack width limits, and ultimate load capacity under both exceptional and fatigue loading conditions. Numerical simulations provide additional insight into stress and displacement distributions in critical cross-sections, supporting the experimental findings. The results indicate that most of prestressing force losses occur during the early service period. This observation supports the application of age-dependent acceptance criteria, which may improve conformity assessment procedures for prestressed concrete railway sleepers in contemporary railway engineering practice. Full article