Bilecik University

The cement industry is one of the most energy-intensive sectors and is responsible for a considerable share of industrial emissions. In cement production, the pre-calcination stage plays a critical role in fuel consumption and pollutant formation. Therefore, replacing coal with cleaner fuels such as liquefied natural gas (LNG) and optimizing combustion conditions are important for improving energy performance and reducing environmental impacts. This study investigates the effects of different LNG flow rates and excess air ratios on the energy efficiency, emission characteristics, environmental impact, and enviroeconomic performance of an LNG-fueled rotary burner used for cement pre-calcination. Experiments were conducted at LNG flow rates ranging from 5 to 30 L/min under different air excess ratio conditions. The results showed that increasing the LNG flow rate reduced both energy efficiency and environmental sustainability. The highest overall energy efficiency of 95.66% was achieved at λ = 1.15 with an LNG flow rate of 5 L/min, while the efficiency generally showed a decreasing trend at higher flow rates. Increasing lambda to 1.15 decreased CO, HC, and soot emissions by approximately 60%, 38%, and 60%, respectively. However, CO2 and NOx emissions increased by 6% and 29%, respectively. Due to the dominant contribution of CO2 and NOx, their combined share in the total environmental impact and enviroeconomic cost reached 99%. Overall, within the investigated operating range, the 5 L/min LNG condition provided the most favourable thermo-environmental performance due to its higher energy efficiency, lower heat-transfer losses, and lower absolute environmental and enviroeconomic burdens, whereas higher LNG flow rates increased the environmental and economic loads.

The gut microbiota represents a complex microbial ecosystem that contributes to host metabolic regulation, immune homeostasis, and intestinal barrier function. Across the lifespan, gut microbial communities exhibit marked taxonomic and functional variation driven by environmental exposures, dietary patterns, medication use, and age-associated immune alterations. These differences are closely linked to chronic inflammatory states and immune dysregulation that accompany aging. This review synthesizes current evidence on age-associated differences in gut microbiota composition and functional capacity, with a focus on microbial traits and metabolic pathways relevant to host–microbe interactions. Pathological aging is frequently associated with reduced microbial diversity, loss of short-chain fatty acid–producing commensal bacteria, and enrichment of opportunistic or pro-inflammatory taxa. In contrast, healthy aging and longevity are commonly associated with more stable, resilient, and metabolically adaptable microbial communities. At the functional level, recurrent alterations in short-chain fatty acid biosynthesis, bile acid transformation, and tryptophan- and choline-related metabolic pathways define conserved features across aging-associated microbial profiles. Across neurodegenerative, metabolic, and cardiovascular conditions, overlapping taxonomic and functional patterns indicate shared microbiota-associated signatures linked to inflammatory states. Advances in metagenomic sequencing, functional annotation, and microbiome-focused biotechnological approaches now enable integrated analysis of microbial structure and metabolic potential. These developments provide a robust framework for identifying reproducible microbiome-based indicators relevant to aging-associated physiological changes and for translating microbiome research into biotechnology-driven applications.

Spexin (SPX) is an endogenous peptide expressed throughout the gastrointestinal tract. Although its impact on postprandial intestinal motility has been examined, its effect during fasting remains unclear. This study aimed to investigate the direct effects of SPX on jejunal and ileal segments in vitro, its effects on fasting small intestinal motility in vivo, and to determine the roles of galanin-2, muscarinic, and 5-hydroxytryptamine-3 (5-HT₃) receptors in these actions. The contractile responses of rat jejunal and ileal segments to SPX (10⁻⁹–10⁻⁶ M), with or without pretreatment with galanin-2, muscarinic, or 5-HT₃ receptor antagonists (M871, atropine, and ondansetron, respectively) were evaluated in organ baths. For in vivo experiments, bipolar electrodes were implanted at two jejunal sites to record migrating myoelectric complexes (MMC), and a catheter was inserted into the left jugular vein for drug administration. SPX (40–640 µg/kg/h) was infused for 1 hour following basal MMC recording. Antagonists were administered 5 minutes prior to SPX (320 µg/kg/h) infusion. SPX induced concentration-dependent contractions in both intestinal segments, significantly inhibited by M871 but unaffected by atropine or ondansetron. At 160 μg/kg/h, SPX altered the MMC pattern; at 320 μg/kg/h, it disrupted MMC and induced irregular spiking activity, which was blocked by M871 and atropine, but not by ondansetron. These data indicate that SPX modulates fasted motility pattern, involving GALR2-dependent mechanisms and an indirect contribution of muscarinic pathways. These findings may support the development of therapies for gastrointestinal motility disorders. In vitro, SPX induced concentration-dependent contractions, which were inhibited by M871 but not affected by atropine or ondansetron. In vivo, SPX disrupted the fasting intestinal myoelectric pattern, an effect that was blocked by M871 and atropine but not by ondansetron.

Hydrothermal carbonization (HTC) represents a promising thermochemical method for converting wet biomass under moderate aqueous conditions into carbon-rich materials, characterized by specific attributes. Notwithstanding the increasing interest surrounding HTC, the current literature remains fragmented regarding the precise mechanisms by which process parameters influence hydrochar formation, its properties, and sustainable utilization. Consequently, the primary objective of this review is to systematically elucidate the fundamental mechanisms that govern HTC, to identify key parameters impacting hydrochar yield and quality, and to assess the sustainability and prospective contributions of HTC within the context of circular economy principles. This paper elaborates on the reaction pathways of hydrolysis, dehydration, decarboxylation, and aromatization that dictate the structural alterations and carbon densification of hydrochars. It emphasizes the roles of temperature, residence time, solid/liquid ratio, catalysts, and feedstock composition in jointly determining hydrochar yield, elemental composition, aromaticity, porosity, and energy density. Additionally, recent advancements, including microwave-assisted HTC, catalytic modifications, and post-activation techniques, are reviewed to enhance hydrochar functionality for applications in energy, adsorption, catalysis, and soil enhancement. Challenges remain regarding the scale-up of the process, reactor design, standardization of hydrochar properties, and the sustainable management or valorization of process water. This review integrates mechanistic insights with recent technological progress to position HTC as a versatile and sustainable method for producing high-value hydrochars, thereby underscoring its potential role in future biorefineries and circular economy initiatives.

Diesel engines, due to their reliance on petroleum-derived fuels for power generation, not only emit high levels of nitrogen oxides and smoke but also contribute significantly to greenhouse gas emissions that drive climate change. Therefore, the use of alternative fuels has become essential to reduce dependency on petroleum-based fuels in these engines. Oxygenated fuels can be effective in minimizing emissions. In this study, ethyl acetate-which is rich in hydrogen and oxygen and considered a potential hydrogen carrier-is used in dual-fuel mode to improve combustion performance and reduce exhaust emissions. Experimentally, the effects of different exhaust gas recirculation rates and injection durations on the combustion and emission characteristics of a compression-ignition engine operating in a diesel-ethyl acetate dual-fuel mode are investigated. The exhaust gas recirculation rates vary as 0 %, 5 %, 10 %, and 20 %, while the ethyl acetate injection duration changes as 1 ms, 2 ms, and 3 ms. Additionally, experiments are conducted at different engine loads (5 kg, 10 kg, 15 kg, and 20 kg) and a constant engine speed of 1800 rpm. The results indicate that increasing the ethyl acetate injection duration reduces the maximum pressure at low loads but increases it at high loads. Moreover, the use of ethyl acetate increases the ignition delay by approximately 11 % and raises the cycle-to-cycle variation to around 23 %. Regarding emissions, increases in injection duration and exhaust gas recirculation rate reduce nitrogen oxides emissions by an average of approximately 39 % and smoke emissions by an average of around 75 %.