Search Results (348)

Two-Stage Anaerobic Digesters (TSADs) have emerged as an effective strategy for improving the stability and efficiency of biogas production from high-strength substrates such as food waste. The separation of acidogenic and methanogenic phases enables better environmental control for distinct microbial communities, thereby enhancing methane yield and reducing process instability. This study investigates the dynamics of microbial populations of acidogens, acetogens, and methanogens in a TSAD using an extended Anaerobic Digester Model No. 1 framework incorporating stage-specific microbial growth kinetics. Simulation scenarios were performed across a range of operational parameters, including OLR (1–8 kg VS/m³ day), pH (5.0–8.0), temperature (35 °C and 45 °C), and HRT (10–30 days). The results demonstrate that balanced microbial population dynamics and syntrophic interactions strongly influence methane production and overall digester performance. Optimal methane yields were achieved within an OLR range of 3.5–4.5 kg VS/m³ day under mesophilic conditions. Elevated loading rates led to VFA accumulation and pH decline, resulting in the inhibition of methanogenic populations and reduced methane output. Preliminary parametric analysis suggests that the acetoclastic methanogen growth rate and ammonia inhibition constants are influential parameters affecting system performance. The findings highlight the importance of integrating microbial population dynamics into AD models to enhance predictive accuracy and support the development of intelligent control strategies for sustainable waste-to-energy systems. Full article

Background: Carotid atherosclerosis is a recognised manifestation of systemic vascular disease, and its association with coronary artery disease (CAD) has been well described. However, previous studies have largely been conducted under conventional diagnostic conditions and have focused on carotid plaque, intima–media thickness, or simple present-versus-absent stenosis classifications, rather than duplex-derived haemodynamic markers across the spectrum of angiographic CAD burden. The COVID-19 pandemic and post-pandemic period changed referral patterns and created more variable cardiovascular presentations, including symptoms that could resemble or mask obstructive CAD. Therefore, we investigated whether the established association between carotid stenosis severity and CAD burden remains detectable in a diagnostically heterogeneous real-world cohort, and whether routinely available carotid duplex haemodynamic parameters provide a clinically relevant signal in this setting. Methods: This single-centre, cross-sectional study was performed as a carotid-focused secondary analysis of the BG Study cohort. We included 902 consecutive patients who underwent invasive coronary angiography between 2021 and 2023 and carotid duplex ultrasonography during the same hospitalisation. CAD burden was defined according to the number of major coronary vessels with ≥70% diameter stenosis and classified as no CAD, one-vessel, two-vessel, or three-vessel disease. Carotid duplex parameters included peak systolic velocities of the common, internal, and external carotid arteries, as well as ICA stenosis severity graded according to NASCET criteria. Associations with CAD burden were assessed using a staged statistical approach combining χ² tests, Kruskal–Wallis tests with post hoc pairwise comparisons, Spearman correlation, inverse probability weighting, and ordered logistic regression. Results: The prevalence of measured ICA stenosis of any grade and severe ICA stenosis increased with greater CAD burden (both p < 0.001). Median PSV values of the bilateral ICAs and ECAs differed significantly across CAD groups on global intergroup testing. Post hoc pairwise analyses showed that significant corrected differences were concentrated between patients without CAD and those with multivessel or three-vessel CAD, particularly for ICA stenosis measures and bilateral ECA PSV. Spearman analysis demonstrated weak but statistically significant correlations between carotid parameters and CAD burden (ρ = 0.085–0.134). After inverse probability weighting, covariate balance was achieved, with all post-IPW standardised mean differences being <0.01. In ordered logistic regression (OLR) analysis, patient-reported history of carotid stenosis (OR 2.25, 95% CI 1.38–3.67; p < 0.001), right external carotid artery PSV per 10 cm/s (OR 1.31, 95% CI 1.09–1.57; p = 0.004), left ICA PSV per 10 cm/s (OR 1.17, 95% CI 1.01–1.36; p = 0.034), and left ICA stenosis per 10% (OR 1.24, 95% CI 1.11–1.39; p < 0.001) were independently associated with higher CAD burden. Exploratory ratio-based analyses showed that the ECA/CCA PSV ratio was associated with CAD presence and higher CAD burden, whereas the ICA/CCA ratio showed weaker associations; neither ratio-based index outperformed absolute ECA PSV. Conclusions: In this carotid-focused secondary analysis of a pandemic-era angiography cohort, carotid stenosis severity and duplex-derived haemodynamic parameters were independently but modestly associated with increasing angiographic CAD burden. These findings support carotid duplex markers as adjunctive indicators of systemic atherosclerotic burden rather than standalone tools for CAD detection or treatment decision-making. Future validation in vascular surgery populations is warranted to determine whether routinely available carotid duplex parameters can contribute to targeted cardiovascular risk recognition before major vascular procedures. Full article

Anaerobic digesters (ADs) are widely used for the recovery of energy from biomass waste, while performance deterioration of ADs sometimes occurs under high organic loads. Microbial electrolysis cells (MECs) have been examined for incorporation into ADs to improve methane production, while responses of MEC-assisted ADs (MEC-ADs) to changes in operational conditions have yet to be sufficiently examined. Here we operated laboratory ADs and MEC-ADs with food waste as a feed, and organic loading rates (OLRs) were varied by changing hydraulic residence times (HRTs). Analyses of AD performances, including methane production and chemical oxygen demand (COD) removal, show that MEC-ADs exhibit higher performances than ADs at OLRs of 7 g COD L⁻¹ D⁻¹ or higher (HRT of 10 days or less). In addition, pH was stably maintained in MEC-ADs at high OLRs. Metabarcoding of rRNA gene amplicons showed that Desulfuromonadaceae bacteria were enriched at the anodes in MEC-ADs, while Methanobacteriaceae archaea were increased at the cathodes. It is suggested that the MEC system is useful for stably operating ADs at high OLRs and/or short HRTs. Full article

Acidogenic fermentation of organic wastes represents a strategic platform for the co-production of H₂, CO₂, and volatile fatty acids (VFAs), which are potential key intermediates for cost-effective polyhydroxyalkanoate (PHAs) biosynthesis. This typically relies on carbon sources that are too expensive and hinder the commercialization of PHAs. This study provides metagenomic insights into the microbial dynamics underpinning the acidogenic conversion of waste melon under increasing organic loading rates (OLRs). Metabarcoding revealed that Megasphaera dominated the community, with its abundance rising markedly from 5 to 20 gCOD/L, accompanied by relevant contributions from Solobacterium, Prevotella, and Clostridium. These taxa were associated with the formation of acetic, propionic, and butyric acids and with enhanced hydrogenogenesis. Higher OLRs, up to 20 gCOD/L, promoted hydrogen-producing species while suppressing lactic acid bacteria, thereby improving H₂ and VFAs yields up to 26.7% v/v and 13 gCOD/L, respectively. By linking microbial shifts to metabolic outputs, this work advances the understanding of acidogenic pathways essential for integrating dark fermentation-derived H₂, CO₂, and VFAs into sustainable PHAs production systems. Full article

In 2024, China generated approximately 130 million tons of food waste. This study focuses on food wastewater characterized by exceptionally high organic strength (chemical oxygen demand (COD) > 80 g·L⁻¹, total suspended solids (TSS) > 20 g·L⁻¹) content. Conventional continuous stirred tank reactors (CSTRs) inherently couple hydraulic retention time (HRT) and sludge retention time (SRT), making them prone to microbial washout under high organic loading. To overcome this limitation, this study employed two anaerobic sequencing batch reactors (ASBRs) for treating such high-strength food wastewater. This study systematically evaluated the impacts of temperature (mesophilic: 37 °C and thermophilic: 55 °C) and organic loading rate (OLR) on fermentation performance. Under stable operation (OLR = 5.6 kg_COD·m⁻³·d⁻¹; HRT = 16 days), the mesophilic ASBR achieved a specific methane yield of 307 mL CH₄·g_CODremoved⁻¹, an average COD removal efficiency of 81%, and a volatile fatty acids-to-total alkalinity (VFA/TA) ratio of 0.2, indicating robust process stability. In contrast, the thermophilic ASBR exhibited a VFA/TA ratio of 0.5, signaling incipient acidification. Microbial community analysis revealed significantly higher bacterial and archaeal alpha diversity in the mesophilic system. Notably, Methanothrix—a versatile acetoclastic methanogen—dominated the mesophilic archaeal community (66.65%), conferring functional redundancy and resilience against organic shock loads. By contrast, the thermophilic system was overwhelmingly dominated by the hydrogenotrophic Methanothermobacter (99.28%), resulting in low functional diversity and structural fragility. Compared with a benchmark mesophilic CSTR (specific methane yield: 276 mL CH₄·g_CODremoved⁻¹; COD removal efficiency: 70.6%), the mesophilic ASBR improved methane yield by 11%, COD removal efficiency by 15%, and operational stability (VFA/TA = 0.2 vs. 0.6). This work addresses a gap in ASBR applications for high-strength food wastewater treatment and provides experimental validation of the performance, stability, and scalability of mesophilic ASBRs. The proposed process represents a technically feasible, resource-efficient, and operationally robust solution for the valorization of organic wastewater with COD > 80 g·L⁻¹ and TSS > 20 g·L⁻¹. Full article

The stabilization of two-stage bioenergy systems and optimization of the energy recovery efficiency have been found to be closely related to the management of VFA-rich effluent obtained after the dark fermentation of food waste. In this study, the performance of a mesophilic UASB reactor was investigated at different OLR levels. The focus of this study was to assess methane yield and substrate degradation during anaerobic digestion. The results revealed that the performance of the UASB reactor was stable within the range of 2.5–7.0 kg COD m⁻³ d⁻¹. At this range, it was possible to convert VFAs into methane gas through the synergistic interaction of fermentative bacteria and methanogenic archaea. The methane content was 67.9%, TCOD removal efficiency was 89.7% at the optimal OLR of 7.0 kg COD m⁻³ d⁻¹, and volumetric methane production rate was 2.41 L_CH4 L⁻¹ d⁻¹. The increase in OLR to 10.0 kg COD m⁻³ d⁻¹ resulted in instability of the anaerobic digestion process. The instability of the anaerobic digestion process was characterized by propionate accumulation and a high VFA/alkalinity ratio of 0.89. The Grau second-order and Modified Stover–Kincannon models were found to describe COD removal efficiency. The Monod model was found to show limited preliminary agreement under the conditions tested for high-rate granular sludge. The highest methane yield and efficiency of energy recovery were obtained at 7.0 kg COD m⁻³ d⁻¹. The recoverable energy obtained at this OLR was 2.04 MJ d⁻¹. The results of this study revealed that it is possible to integrate dark fermentation and anaerobic digestion through the use of UASB reactors. Full article

Growing municipal solid wastes, environmental deterioration, and the world’s increasing energy demand highlight the urgent need for effective, sustainable energy recovery solutions. Uncontrolled municipal solid wastes contribute explicitly to the global crises of climate change, pollution, and biodiversity loss. Food and organic waste are converted into value-added products using biochemical and thermochemical techniques. Anaerobic digestion (AD) is a versatile, multi-phase waste-to-energy technology that transforms organic waste into renewable energy in an oxygen-free environment. AD uses microorganisms to break down waste, yielding biogas (mostly methane and carbon dioxide) and digestate, a nutrient-fortified by-product. Compared with traditional Single-Stage Anaerobic Digesters (SSAD), Two-Stage Anaerobic Digesters (TSAD) offer notable benefits by separating hydrolysis–acidogenesis from acetogenesis–methanogenesis. These include increased methane yield, improved process control, increased microbial stability, and resistance to inhibitory substances. According to the literature, TSAD systems have been shown to increase methane yield by about 10–30% compared to SSAD. This article covers the dynamics of the microbial population at various stages, the impact of operational factors (HRT, OLR, pH, and temperature), and novel reactor designs with modular and multi-state functions. In line with Oman’s Vision 2040, this study discusses the continuous operation of a two-phase AD co-digestion process and the in-depth techno-economic feasibility of decentralized waste management through optimized biogas production. Optimizing the carbon-to-nitrogen (C/N) ratio within the range of 20–30 in co-digestion systems significantly enhances microbial activity and methane production. The potential of recent developments, such as microbial immobilization, biogas generation techniques, and hybrid integration with photobioreactors or electrochemical systems, to enhance the scalability and efficiency of bioconversion is addressed in a TSAD system. In addition to encouraging circular economy principles through efficient organic waste valorization, this review identifies TSAD as a promising approach to achieving the SDGs related to sustainable cities, clean energy, and responsible consumption. Full article

The energy and environmental advantages of anaerobic digestion have led to a gradual growth in interest in biogas technology in recent years. Opportunities are presented by anaerobic digestion technology to produce renewable energy, minimize greenhouse gas discharge into the atmosphere, and minimize the release of waste in landfills. The study aims to consider the state of the art of biogas development while exploring emerging trends in optimization parameters and tools. Optimizing process parameters such as temperature, HRT, pH, and OLR were considered, which are essential to maximize digesting efficiency and biogas yield. Some optimizing tools were also discussed, such as Aspen Plus, MATLAB/Simulink, RSM, and ANN. The effective use of the optimization process parameters and tools will help to promote the optimum use of biomass for biogas generation, thereby promoting clean and affordable energy, as well as policies that minimize the emission of GHG, and contribute to the UN SDGs 7 and 13. More research needs to be carried out on the development and utilization of advanced optimization tools and techniques, which will enhance the use of biomass for biogas generation. Full article

The China–Pakistan Economic Corridor (CPEC) represents a transformative transport infrastructure initiative with the potential to reshape tourism in South Asia. However, the behavioral mechanisms through which corridor development translate into travel willingness remain insufficiently understood, particularly between domestic and cross-border tourism. This study investigated the determinants of domestic tourism willingness within Pakistan and cross-border tourism willingness toward China using a stated preference survey of 441 Pakistani respondents collected through an online questionnaire. To balance behavioral interpretation and predictive performance, this study integrated ordinal logistic regression (OLR) with multiple machine learning classifiers. The results revealed clear behavioral asymmetries between domestic and cross-border tourism decisions. Domestic tourism willingness was primarily driven by attitudinal evaluations, particularly perceived desirability, pleasantness, and comfort of travel along the CPEC. In contrast, cross-border tourism willingness was more strongly constrained by knowledge-related and institutional factors, including awareness of visa procedures, accommodation arrangements, and destination information. Comparative performance analysis indicated that machine learning models outperformed ordinal logistic regression, improving predictive accuracy by approximately 12.6 percentage points for domestic tourism (93.6% vs. 81.0%) and 1.7 percentage points for cross-border tourism (81.1% vs. 79.4%). These findings demonstrate that corridor-induced tourism demand is governed by distinct behavioral mechanisms across domestic and international contexts, highlighting the need for differentiated tourism development strategies. From a policy perspective, the results suggest that domestic tourism development along the CPEC should prioritize experiential quality and travel comfort, whereas cross-border tourism promotion should focus on reducing informational and procedural barriers such as visa knowledge, accommodation awareness, and travel facilitation. Full article

To advance our understanding of atmospheric processes and climate dynamics, improved knowledge of outgoing long-wave radiation (OLR) spectral emission is essential. The FORUM mission, selected for the ninth cycle of the European Space Agency’s Earth Explorer programme, is specifically designed to address the long-standing observational gap in the far-infrared (FIR) spectral region. When combined with measurements from the IASI-NG instrument, FORUM will provide complete spectral coverage of Earth’s OLR emission (spanning 100 to 2760 cm⁻¹ wavenumber, or 3.62 to 100 μm wavelength), thereby enabling robust climate model validation and enhanced understanding of climate change processes. While IASI-NG’s primary mission is to support numerical weather prediction, FORUM is designed to measure key climate variables, which also enable the retrieval of atmospheric parameters in the troposphere and lower stratosphere. In this study, we assess the information content of FORUM and IASI-NG measurements for atmospheric profiling through a simulation-based approach. Synthetic retrieval products are generated using a linearized formulation of the retrieval transfer function, allowing an efficient and physically consistent evaluation of the sensitivity of the two instruments to atmospheric temperature and water vapor profiles. The analysis reveals a non-negligible sensitivity of FORUM to atmospheric temperature extending into the stratosphere, resulting in significant information content at altitudes higher than previously reported. This finding highlights the potential of far-infrared observations to contribute to atmospheric temperature profiling beyond the lower troposphere. The complementary capabilities of FORUM and IASI-NG suggest that their combined use can enhance the characterization of the atmospheric thermal structure. These results represent a first step toward evaluating the potential role of FORUM Level-2 products in future numerical weather prediction applications. Full article

Thermal hydrolysis pretreatment (THP) increases the solubilization of sewage sludge, while bioelectrochemically assisted anaerobic digestion (BEAD) enhances the conversion of the solubilized organic matter into methane and improves reactor stability in the presence of inhibitory compounds. In this study, by mapping methane production in a BEAD reactor against the soluble organic loading rate (sOLR), determined from soluble chemical oxygen demand (sCOD) measurements, distinct operational regimes corresponding to different THP temperatures were identified. With the 120 °C pretreated feedstock, the BEAD reactor operated in a hydrolysis-limited regime, where increasing sOLR increased methane production but reduced conversion efficiency. Accordingly, at an sOLR of 4.5 g (L_R d)⁻¹, a volumetric methane production rate of 0.8 L L_R⁻¹ was achieved. Increasing THP severity to 150 °C improved solids solubilization and shifted the system into a kinetically enhanced regime, in which methane production was directly proportional to sOLR, indicating improved substrate accessibility and reaction kinetics. Consequently, at an sOLR of 7.75 g (L_R d)⁻¹, methane production reached 1.46 L L_R⁻¹. This regime-based analysis provides quantitative guidance for selecting pretreatment severity and loading strategies to maximize methane production, while maintaining stable BEAD reactor operation at high organic loads. Full article

Constructed wetlands (CWs) have emerged as effective nature-based solutions (NbS) for the treatment of industrial dairy wastewater (DWW), which is characterized by high organic loads, elevated nutrient concentrations, and pronounced operational variability. Despite increasing implementation, quantitative engineering evidence supporting design optimization and scalability remains fragmented. Herein, we present a semi-quantitative synthesis of CW performance for DWW treatment, explicitly linking hydraulic and operational parameters with pollutant removal efficiencies. A systematic review of 38 peer-reviewed studies published between 1995 and 2025 was conducted in accordance with PRISMA 2020 guidelines. Treatment performance was normalized and evaluated as a function of hydraulic retention time (HRT), organic loading rate (OLR), system configuration, and climatic context. The results demonstrate that hybrid CWs combining vertical and horizontal subsurface flow most frequently achieved COD and BOD₅ removal efficiencies exceeding 90% when operated within an observed operating envelope, typically including HRT ranges of 4–8 h (VSSF; n = 4) and 3–7 days (HSSF; n = 14), and OLR values below 30 g COD m⁻² d⁻¹ (n = 7, among studies reporting OLR). Operation outside this operating envelope was generally associated with reduced treatment stability and an increased likelihood of operational constraints (e.g., clogging). Substrate porosity, vegetation diversity, and climate further modulated long-term performance and system resilience. Based on the consolidated evidence, this review suggests transferable operational design envelopes and configuration-specific implementation pathways that translate empirical findings into practical engineering guidance, supporting the scalable adoption of CWs as low-energy NbS for decentralized and sustainable DWW management. Full article

Distant metastasis is the main cause of breast cancer (BC) mortality, yet current prognostic models remain largely tumor-centric and underutilize stromal biology. In this study, we quantified reactive stroma, a collagen-rich and fibrotic fraction of the stromal compartment, as a subtype-independent biomarker of metastatic risk. A retrospective cohort of 182 FFPE primary BC biopsies (2006–2020) was analyzed. Total stroma was quantified on H&E-stained sections and reactive stroma on Masson’s trichrome using QuPath with pathologist validation. Cutoffs were defined using maximally selected rank statistics, and overall survival (OS) and metastasis-free survival (MFS) were evaluated by Kaplan–Meier analysis and multivariable Cox regression. RNA sequencing was performed in a subset of cases to characterize associated transcriptomic programs. While total stromal content showed univariate associations with OS and MFS, it was not independently prognostic after adjustment. In contrast, high reactive stroma (cutoff 53.2%) independently predicted shorter MFS (HR = 3.76; p < 0.001), irrespective of molecular subtype and clinicopathological variables. Tumors with high reactive stroma exhibited upregulation of extracellular matrix and profibrotic genes (including FN1, OLR1, and EDN2), enrichment of collagen remodeling and TGF-β signaling pathways, and reduced T-cell activation signatures. These findings demonstrate that quantitative assessment of reactive stroma from standard histological stains is a reproducible, subtype-independent biomarker of metastatic risk in BC and can be readily integrated into routine pathology workflows to improve risk stratification. Full article

Maize silage can play a key role in policies aimed at stabilising local energy systems, as it constitutes a critical renewable feedstock for European biogas plants. By providing a dense and predictable source of chemical energy, it supports balance and reliability in the agricultural energy sector. To convert this potential into stable energy production, operators require kinetic models that translate routine silage quality indicators into concrete guidance for digester operation and control. Therefore, the aim of this article was to evaluate the batch kinetics of anaerobic digestion (AD) of maize silage and to select an adequate model for describing biochemical methane potential (BMP) profiles and associated energy recovery in the context of start-up, organic loading rate (OLR), hydraulic retention time (HRT) and feedstock preparation. Ten batches of silage (A–J) were examined, covering a realistic range of pH, electrical conductivity (EC), dry and volatile solids, ash, protein–fat–fibre fractions, fibre composition (NDF, ADF and ADL), derived fractions (hemicellulose, cellulose, and residual organic matter (OM)), C/N ratio and macro-/micronutrient profiles, including trace elements relevant to methanogenesis (Ni, Co, Mo, and Se). BMP tests were carried out in batch mode, and the resulting curves were fitted using the modified Gompertz and a first-order kinetic model. Methane yields of approx. 100–120 m³ CH₄/Mg fresh matter (FM) and 336–402 m³ CH₄/Mg volatile solids (VS), with CH₄ contents of 52–57% v/v, were typical for energy-grade maize silage. Kinetic and energetic behaviours were governed mainly by residual OM and hemicellulose (shortening the lag phase and increasing the maximum methane production rate), the ADL/cellulose ratio (controlling the slower hydrolytic tail), EC and Na/Cl/S (extending the lag phase), and C/N together with Ni/Co/Mo/Se (stabilising methanogenesis). The modified Gompertz model reproduced BMP curves with a pronounced lag phase and asymmetry more accurately (lower error and better information criterion values), and its parameters directly support start-up design, OLR ramp-up and energetic performance optimisation in bioenergy reactors. The novelty of this work lies in combining batch BMP tests, comparative kinetic modelling and detailed silage characterisation to establish quantitative links between kinetic parameters and routine maize silage quality indicators that are directly relevant for biogas plant operation and renewable energy production. Full article

We present the single-cell transcriptomic analysis of peripheral blood mononuclear cells (PBMC) from individuals during acute HIV-1 infection caused by viral strains circulating in Russia and the Former Soviet Union (FSU) countries. Using 10x Genomics single-cell RNA sequencing (scRNA-seq) on the Illumina NextSeq 550 platform, we have analyzed scRNA-seq data from three treatment-naive patients (viral load > 1 × 10⁶ copies/mL, estimated infection duration ≤ 4 weeks) and three healthy donors. Data integration (Seurat, Harmony), automated cell-type annotation (CellTypist), and GeneOntology (GO) enrichment analysis for highly expressed and low-expressed genes revealed a profound reorganization of transcriptional programs across key immune populations, including memory CD4⁺ and CD8⁺ T cells, non-classical monocytes and natural killer cells (NK-cells). We observed signatures of hyperactivation of pro-inflammatory pathways (NF-kB, TNF, and type I/II interferon signaling), upregulation of genes associated with cellular migration (CXCR4, CCR7) and metabolic adaptation (oxidative phosphorylation components), alongside a mixed pro- and anti-apoptotic expression profile. Notably, our data pointed to a pronounced dysregulation of the TGF-β and mTOR signaling cascades, disrupted intercellular communication networks—particularly between cytotoxic cells and their regulators—altered expression of genes implicated in disease progression (OLR1, SERPINB2, COPS9) and viral persistence control (NEAT1, NAF1). This work provides an initial single-cell transcriptional atlas characterizing early immune responses to HIV-1 sub-subtypes A6 and CRF63_02A6, the predominant drivers of the HIV epidemic across the FSU region. Full article