Search Results (220)

Water source identification and dynamic assessment are critical for mining safety, particularly in mines governed by complex geological structures. The hydrochemical mixing model demonstrates a natural advantage for early warning of water intrusion compared to geophysical monitoring techniques. This study discusses core issues related to the mixing model, including the conceptual framework, selection of end-members, and choice of tracers, and formulates principles for general applicability. In this study, three sources were identified using the conceptual model and hydrochemical analysis: water in F7 (main fault), shallow fracture water, and river water. A correlation analysis and variability analysis were applied to determine the tracers, and the ¹⁸O, D, Cl, B, and Li were determined. The end-members of the three sources are time-dependent in July and September, especially the shallow fracture water’s end-members. The dynamics of the mixing ratios of the three sources suggest that river water contributes only to the inrush (1–4%), with this being especially low in September, as the increasing hydraulic gradient from south to north prevents recharge. The water in F7 accounts for at least 70% of the inrush water. Shallow fracture water accounts for the rest and increases slightly in September as the precipitation increases in mining-disturbed areas. Finally, this work makes the later water control work more targeted. Full article

Accurate photovoltaic (PV) panel characterization is critical for optimizing renewable energy systems, but it is often hindered by the high cost of commercial tracers or the slow, error-prone nature of manual methods. This paper presents a low-cost, Arduino-based I–V curve tracer that overcomes these limitations through fully automated resistive load switching. By integrating a relay-controlled resistor bank managed by a single microcontroller, the system eliminates the need for manual intervention, enabling rapid and repeatable measurements in just 45 s. This rapid acquisition is a key advantage over manual systems, as it minimizes the impact of fluctuating environmental conditions and ensures the resulting I–V curve represents a stable operating point. Compared to commercial alternatives, our open-source solution offers significant benefits in cost, portability, and flexibility, making it ideal for field deployment. The system’s use of fixed, stable resistive loads for each measurement point also ensures high repeatability and straightforward comparison with theoretical models. Experimental validation demonstrated high agreement with a single-diode PV model, achieving a mean absolute percentage error (MAPE) of 4.40% against the manufacturer’s data. Furthermore, re-optimizing the model with field-acquired data reduces the MAPE from 18.23% to 7.06% under variable irradiance. This work provides an accessible, robust, and efficient tool for PV characterization, democratizing access for research, education, and field diagnostics. Full article

Groundwater sustains ecosystems, agriculture, and human consumption; therefore, its interaction with hydrocarbons is an important area of research under the umbrella of environmental science and resource exploration. Naturally occurring or anthropogenically introduced hydrocarbons can significantly impact groundwater through complex geochemical processes such as dissolution, adsorption, biodegradation, and redox reactions and can also affect groundwater chemistry in terms of pH, redox potential, dissolved organic carbon, and trace element concentrations. Accurate determination and identification of hydrocarbon contaminants requires advanced analytical methods like gas chromatography, GC–MS, and fluorescence spectroscopy, complemented with isotopic analysis and microbial tracers, which provide insights into sources of contamination and biodegradation pathways. The presence of hydrocarbons in groundwater is a matter of environmental concern but can also valuable data for petroleum exploration, tracing subsurface reservoirs and seepage pathways. This paper refers to the basic need for geochemical investigations combined with advanced detection techniques for successful regulation of thermal–mineral groundwater quality. This contributes towards successful sustainable hydrocarbon resource exploration and water resource conservation, with emphasis on the relationship between groundwater quality and hydrocarbon exploration. The study points out the significance of continuous observation of thermal mineral waters to identify their connection with the specific hydrocarbons of each study area. Full article

This review discusses the causes, nature, importance and observational evidence of mass loss by red supergiants. It arrives at the perception that mass loss finds its origin in the gravity which makes the star a star in the first place, and is a mechanism for the star to equilibrate. This is corroborated by a careful examination of various popular historical and recent empirical mass-loss rate prescriptions and theoretical works, and which provides no evidence for an explicit dependence of red supergiant mass loss on metallicity though dust-associated mass loss becomes less prevalent at lower metallicity. It also identifies a common problem in methods that use tracers of mass loss, which do not correct for varying scaling factors (often because there is no information available on which to base such correction) and as a result tend to underestimate mass-loss rates at the lower end. Conversely, dense, extended chromospheres in themselves do not translate into high mass-loss rates, and the significance of stochastic mass loss can be overstated. On a population scale, on the other hand, binary interaction acts as a stochastic agent of mass loss of great import. In all, evidence is overwhelming that points at red supergiants at the lower mass end losing mass at insufficient rates to shed their mantles before core collapse, but massive (at birth) red supergiants to be prone to intense, dusty mass loss which sees them become hotter stars before meeting their fate. This is consistent with the identified progenitors of hydrogen-rich supernovae. Supernova evolution holds great promise to probe the mass loss but we caution against confusing atmospheres with winds. Finally, promising avenues are looked into, which could forge step-change progress in what has been a long and arduous search for the holy grail of red supergiant mass loss. We may yet find it! Full article

Fibromyalgia syndrome (FMS) is a complex, heterogeneous disorder characterized by chronic widespread pain, fatigue, and cognitive disturbances. The multifactorial nature of FMS, with the involvement of central and peripheral mechanisms, hampers diagnosis and effective treatment. In recent years, positron emission tomography (PET) imaging has emerged as a valuable tool for exploring the neurobiological underpinnings of FMS. Several studies have investigated alterations in glucose metabolism, neurotransmitter systems (including opioid, dopamine, and GABAergic pathways), and neuroinflammation using various PET tracers. These findings have revealed distinct brain metabolic and molecular patterns in FMS patients compared to healthy controls, particularly in pain-related regions such as the thalamus, insula, and anterior cingulate cortex (ACC). Moreover, preliminary data suggest that PET imaging may help identify FMS subgroups with different pathophysiological profiles, potentially allowing for tailored therapeutic approaches. This review summarizes the current evidence on PET applications in FMS and discusses the potential role of molecular imaging in improving patient stratification and predicting treatment response. Full article

Purpose: The skeletal muscle has been proposed to contribute to the progressive loss of motor neurons typical of amyotrophic lateral sclerosis (ALS). However, this mechanism has not yet been clarified due to the lack of suitable imaging tools. Here, we aimed to verify whether PET imaging of the translocator protein 18 kDa (TSPO) can detect a muscular abnormality in an experimental model of ALS. Methods: In vivo biodistribution and kinetics of [¹⁸F]DPA-714 were analyzed in skeletal muscle and brain of SOD1^G93A transgenic mice and in wildtype (WT) littermates. Both cohorts were divided into three groups (n = 6 each) to be studied at 60, 90 and 120 days. After microPET imaging, animals were sacrificed to evaluate inflammatory infiltrates by hematoxylin/eosin staining and TSPO expression by immunohistochemistry and Western blot in both quadriceps and brain. Results: [¹⁸F]DPA-714 uptake was higher in the skeletal muscles of SOD1^G93A than in WT mice in the preclinical phase (60 and 90 days) and further increased up to the symptomatic late stage (120 days). Inflammatory cells were absent in the quadriceps of SOD1^G93A mice whose myocytes, instead, showed a progressive increase in TSPO expression with advancing age. By contrast, brain tracer uptake and TSPO expression were comparably low in both groups, regardless of age and genotype. Conclusion: Upregulation of TSPO expression is characteristic of skeletal muscle, but not the brain, in the experimental SOD1^G93A mouse model of ALS. Tracers targeting this pathway have been mostly proposed for the evaluation of inflammatory processes within the central nervous system. Nevertheless, the ubiquitous nature of TSPO expression and its responsiveness to various signals may broaden the diagnostic potential of these tracers to include disease conditions beyond inflammation. Full article

Gamma-ray analysis is a widely used technique for radioactive element characterization in environmental samples, contributing significantly to natural and anthropogenic radioactivity evaluations, particularly in areas such as natural reservations or regions that have been affected by nuclear pollutants. As the Danube Delta belongs to both categories, we decided to conduct a study in order to find out whether gamma spectroscopy is suited for pattern identification in common biota constituents such as reed and whether anthropogenic tracers can still be found in the samples. The answer to both questions is affirmative, as shown by the pattern and cluster analyses. Furthermore, our conclusions point out that it would be interesting to extend the spectroscopy and correlation studies to sediment and trophic chains over a certain period in order to obtain the transfer factors and information on radionuclide dynamics. The HPGe detector used proves this is the best class of sensing devices for such purposes. Full article

The indoor climate quality in classrooms at the University of Coimbra, Portugal, was investigated as part of the 3SqAir project, supported by the Interreg SUDOE program. This research focused on two equipped classrooms with different ventilation systems: natural and mechanical ventilation. Both classrooms were continuously monitored for IEQ parameters: thermal comfort, indoor air quality, noise, and lighting during heating and cooling seasons. Air temperature, relative humidity, CO₂ concentration, particulate matter, nitrogen dioxide, volatile organic compounds, formaldehyde, sound pressure level, and illuminance were measured. Outdoor weather conditions were also recorded. The primary focus was on air temperature, CO₂ concentrations, and relative humidity, while air change rates (ACH) were estimated using the Tracer Gas Method. The results showed inadequate thermal conditions in both classrooms, particularly during the heating season. Most weekly mean CO₂ concentrations were within acceptable limits, while ACH were below standard recommendations in four CO₂ decay phases. Simulations of CO₂ decay revealed further air quality gaps in each room. Corrective measures within the 3SqAir project framework were suggested for approval and implementation while monitoring continues. This work represents the first phase in an evolving study towards developing sustainable strategies for improving indoor air quality in classrooms. Full article

Constructed wetlands (CWs) are a sustainable, nature-based solution for wastewater treatment, where pollutants are removed through contact with microorganisms attached to substrates and plant roots. Efficient hydraulic performance is critical for CWs, since poor hydraulic performance can reduce treatment efficiency by altering the actual residence time relative to the design value. Two methods to evaluate the Residence Time Distribution (RTD) within the CW system are the tracer method and numerical modelling. This study provides a comprehensive review of experimental methodologies and numerical models used to investigate hydraulic processes in CWs, outlining available techniques to assist researchers in selecting the most suitable approach based on their research needs and wetland characteristics. For experimental procedures, this review focuses on the selection of tracers, indicators for hydraulic performance assessment, and water quality responses to changing hydrological conditions. The advantages and disadvantages of existing numerical models, their suitability, and future research direction are also discussed. Understanding these methodologies and their application is crucial for advancing our knowledge of the hydraulic features of CWs and improving their design and operation. Ultimately, improving hydraulic performance through appropriate experimental and modelling techniques supports the sustainable development and operation of CW systems for long-term wastewater treatment applications. Full article

Indoor air quality (IAQ) in higher education institutions’ dormitories, without mechanical ventilation, is a significant concern for students’ health due to prolonged occupancy in cold regions. The present investigation assessed IAQ by measuring two dormitories’ CO₂, temperature, and relative humidity with the presence of one, two, three, and four occupants in the United Kingdom. Considering the possibility of natural ventilation by opening the windows in the summer, IAQ was monitored using two sensors located at 1 m and 2 m heights from the floor level of the dormitories in July. The tracer mass balance model showed close agreement with the monitored IAQ levels, with a direct relationship observed between occupant numbers and CO₂ build-up. CO₂ levels exceeded 1000 ppm within an hour during occupancy and closed ventilation, with air exchange rates between 0.12 and 0.2 h⁻¹, increasing to 1334, 1259, 1884, and 2064 ppm after 30 min with one, two, three, and four occupants, respectively. Desired IAQ standards (1000 ppm) were achieved in 13, 33, 80, and 86 min for one, two, three, and four occupants after starting natural ventilation by opening 20% of the windows. The analysis of variance affirmed the effect of occupancy on IAQ, while the impact of height (1 m and 2 m) on CO₂ levels was insignificant. This study underscores the need to effectively ventilate the partial opening of windows in dormitories to mitigate CO₂ build-up, ensuring the desired ambient environment within dormitory rooms during summers in cold regions. Full article

In this work, we study the Coma cluster, one of the richest and most well-known systems at low redshifts, to explore the importance of low-flux objects in the identification of cluster substructures. In addition, we conduct a study of the infall flow around Coma, considering the presence or absence of low-flux objects across the projected phase space of the cluster. Our results indicate that low-luminosity galaxies play a fundamental role in understanding the dynamical state of galaxy clusters. These galaxies, often overlooked because of their faint nature, serve as sensitive tracers of substructure dynamics and provide crucial insights into the cluster’s evolutionary history. We show that not considering the low-flux objects present in clusters can lead to significant underestimates of the numbers of substructures, both in most central parts, in the infall regions, and beyond, connecting to the large-scale structure up to a distance of ∼8$R_{200}$ from the center of Coma. Full article

This study aimed to clarify the scientific quantification of fertilizer nitrogen (N) uptake and utilization, its destination, and its residual distribution in the soil at a depth of 0–30 cm after biochar application using ¹⁵N tracer technology. The purpose was to provide a theoretical basis for developing a scientific application strategy for N fertilizer and biochar in irrigated farmland areas. Two levels of N fertilizer application were set up using the ¹⁵N labeling method in microareas of large fields: the regular amount of N fertilizer (N1: 300 kg·ha⁻¹) and a reduction of N fertilizer by 15% (N2: 255 kg·ha⁻¹). Further, three levels of biochar application were set up: no biochar (B0: 0 kg·ha⁻¹), a low amount of biochar (B1: 10 × 10³ kg·ha⁻¹), and a medium amount of biochar (B2: 20 × 10³ kg·ha⁻¹). The tested biochar was derived from corn stover (maize straw). The natural abundance of ¹⁵N-labeled fertilizer N, the total N content of each aboveground organ, and the total N content of soil at a depth of 0–30 cm in a spring wheat field at maturity were determined, and the yield was measured in the corresponding plots. The proportion of ¹⁵N-labeled fertilizer N uptake by each organ of spring wheat and the soil N uptake was 20.60–35.32% and more than 64.68%, respectively. Moreover, the proportion of soil N uptake showed a decreasing trend with an increase in biochar application. The spring wheat N uptake and utilization rate, the residue rate in the soil at a depth of 0–30 cm, the total utilization rate, and the rate of loss of ¹⁵N-labeled fertilizer N ranged from 15.21% to 29.61%, 23.33% to 28.93%, 38.54% to 58.54%, and 41.46% to 61.46%, respectively. The spring wheat N fertilizer utilization rate, fertilizer N residue rate in soil, and total fertilizer N utilization rate all increased gradually with an increase in biochar application, except for the N loss rate, which decreased gradually. When N fertilizer reduction was combined with medium biochar (B2N2), the yield of spring wheat significantly improved, mainly due to an increase in the number of grains in spikes. Under this treatment, the number of grains in spikes of spring wheat was 41.9, and the yield reached 7075.54 kg·ha⁻¹, which was an increase of 9.69–28.25% and 10.91–25.35%, respectively, compared with other treatments. Yield increased by up to 25.35%, and nitrogen loss decreased by 48.24% under the B2N2 treatment. Biochar application could promote the amount and proportion of fertilizer N uptake in various organs of spring wheat as well as in the soil at a depth of 0–30 cm. In this study, a 15% reduction in N fertilizer (255 kg·ha⁻¹) combined with 20 × 10³ kg·ha⁻¹ biochar application initially helped achieve the goal of increasing spring wheat yield and N fertilizer uptake, as well as improving fertilizer N utilization, providing an optimal scientific application strategy for N fertilizer and biochar in the farmland of the irrigation area. These results substantiate the hypothesis that biochar application enhances spring wheat (Triticum aestivum L.) assimilation of fertilizer-derived nitrogen (¹⁵N) while concomitantly improving fertilizer nitrogen retention in the soil matrix, which could provide a sustainable framework for nitrogen management in irrigated farmlands. Full article

The fluorescence index called the Transit Time index (TTi) is based on the fluorescence of natural organic matter in order to qualitatively assess the transit time of karst groundwater, using springs affected by human activities. This study aims to further evaluate the potential of fluorescent compounds as a natural tracer of transit time when applied to unsaturated zone flows with natural catchments, in contrast to the first study. For this purpose, a bi-monthly sampling of one year of monitoring for organic matter fluorescence, TOC, major elements and water-stable isotopes was performed. A conceptual model of the sources and fates of fluorescent compounds is built, emphasizing the allochthonous origin of humic-like C compounds, and the autochthonous production of humic-like M and protein-like compounds within the unsaturated zone. Fluorescent compound intensity interpretation according to this model reveals consistent relative transit times with flow behavior and also provides complementary information. The results also show the TTi’s ability to summarize fluorescent compounds, its consistency with relative transit time, and its higher sensitivity as compared to other natural tracers. However, prior to its use, a thorough assessment of soil organic matter, microbial activity, and potential anthropogenic contamination is required, encouraging interdisciplinary collaboration between hydrogeologists, microbiologists and soil scientists. Full article

We introduce a new model for non-linear endmember extraction and spectral unmixing of hyperspectral imagery called Generative Simplex Mapping (GSM). The model represents endmember mixing using a latent space of points sampled within a $(n-1)$-simplex corresponding to n unique sources. Barycentric coordinates within this simplex are naturally interpreted as relative endmember abundances satisfying both the abundance sum-to-one and abundance non-negativity constraints. Points in this latent space are mapped to reflectance spectra via a flexible function combining linear and non-linear mixing. Due to the probabilistic formulation of the GSM, spectral variability is also estimated by a precision parameter describing the distribution of observed spectra. Model parameters are determined using a generalized expectation-maximization algorithm, which guarantees non-negativity for extracted endmembers. We first compare the GSM against three varieties of non-negative matrix factorization (NMF) on a synthetic data set of linearly mixed spectra from the USGS spectral database. Here, the GSM performed favorably for both endmember accuracy and abundance estimation with all non-linear contributions driven to zero by the fitting procedure. In a second experiment, we apply the GTM to model non-linear mixing in real hyperspectral imagery captured over a pond in North Texas. The model accurately identified spectral signatures corresponding to near-shore algae, water, and rhodamine tracer dye introduced into the pond to simulate water contamination by a localized source. Abundance maps generated using the GSM accurately track the evolution of the dye plume as it mixes into the surrounding water. Full article

Metabolism plays a central role in cancer progression. Rewiring glucose metabolism is essential for fulfilling the high energy and biosynthetic demands as well as for the development of drug resistance. Nevertheless, the role of other diet-abundant natural sugars is not fully understood. In this study, we performed a comprehensive 2D NMR spectroscopy tracer-based assay with a panel of ¹³C-labelled sugars (glucose, fructose, galactose, mannose and xylose). We assigned over 100 NMR signals from metabolites derived from each sugar and mapped them to metabolic pathways, uncovering two novel findings. First, we demonstrated that mannose has a semi-identical metabolic profile to that of glucose with similar label incorporation patterns. Second, next to the known role of fructose in driving one-carbon metabolism, we explained the equally important contribution of galactose to this pathway. Interestingly, we demonstrated that cells growing with either fructose or galactose became less sensitive to certain one-carbon metabolism inhibitors such as 5-Flurouracil and SHIN1. In summary, this study presents the differential metabolism of natural sugars, demonstrating that mannose has a comparable profile to that of glucose. Conversely, galactose and fructose contribute to a greater extent to one-carbon metabolism, which makes them important modulators for inhibitors targeting this pathway. To our knowledge, this is the first NMR study to comprehensively investigate the metabolism of key natural sugars in AML and cancer. Full article