High Energy Demand Research Articles

Adenosine signalling to astrocytes coordinates brain metabolism and function

Brain computation performed by billions of nerve cells relies on a sufficient and uninterrupted nutrient and oxygen supply1,2. Astrocytes, the ubiquitous glial neighbours of neurons, govern brain glucose uptake and metabolism3,4, but the exact mechanisms of metabolic coupling between neurons and astrocytes that ensure on-demand support of neuronal energy needs are not fully understood5,6. Here we show, using experimental in vitro and in vivo animal models, that neuronal activity-dependent metabolic activation of astrocytes is mediated by neuromodulator adenosine acting on astrocytic A2B receptors. Stimulation of A2B receptors recruits the canonical cyclic adenosine 3′,5′-monophosphate–protein kinase A signalling pathway, leading to rapid activation of astrocyte glucose metabolism and the release of lactate, which supplements the extracellular pool of readily available energy substrates. Experimental mouse models involving conditional deletion of the gene encoding A2B receptors in astrocytes showed that adenosine-mediated metabolic signalling is essential for maintaining synaptic function, especially under conditions of high energy demand or reduced energy supply. Knockdown of A2B receptor expression in astrocytes led to a major reprogramming of brain energy metabolism, prevented synaptic plasticity in the hippocampus, severely impaired recognition memory and disrupted sleep. These data identify the adenosine A2B receptor as an astrocytic sensor of neuronal activity and show that cAMP signalling in astrocytes tunes brain energy metabolism to support its fundamental functions such as sleep and memory.

Sustainable bio-jet fuel synthesis techniques for the aviation industry

Abstract In the near future, the aviation industry is expected to significantly increase the usage of “drop-in” bio-jet fuel as the technologies in biofuel production advances and matures. Given the high rate of growth in the aviation sector, the demand for aerial transportation of passenger and cargo is projected to increase by two-fold in the next twenty years. This will raise the global aviation fuel consumption to an estimated 22.48 quadrillion British thermal unit (BTU) by 2040. To meet these high energy demands, it is necessary to develop alternative and sustainable methods to produce jet fuel. In light of this, intense research and numerous fundings have been allocated into developing efficient production methods for bio-jet fuel. Conventional jet fuel emits a considerable amount of greenhouse gases (GHGs) when combusted, which contributes to global warming. Compared to traditional jet fuel, bio-jet fuel is a renewable energy source and regarded to emit less GHGs. Bio-jet fuel can be produced using a diverse range of both edible (food crops such as soybean, corn, and sugar cane) and inedible (such as energy crops, agricultural wastes, and lignocellulosic biomass) feedstocks. There are various promising technologies that can produce aviation biofuel, which includes oil-to-jet [hydroprocessed ester and fatty acids (HEFA)], alcohol-to-jet, sugar-to-jet [hydroprocessing of fermented sugars (HFS)], and syngas-to-jet [Fisher-Tropsch (FT)]. Compared to the other techniques, HEFA bio-jet fuel can be sold at a lower price because HEFA requires less capital investment, capital cost, and energy cost. Although FT technique require high capital investment, FT bio-jet fuel can be sold at medium price due to its matured technology. The breakeven cost of ATJ and HFS bio-jet fuel varies greatly due to the supply and cost of sugar-rich feedstocks, as well as short lifespan of enzymes. Although bio-jet fuel has the potential to replace petroleum jet fuel in the future, there are still many technological and socio-economic challenges that must be overcome. Therefore, this paper aims to highlight the current status, technological advances, and economic challenges of bio-jet fuel production for energy transition in the aviation industry.

Unlocking new potentials in energy-efficient carbon dioxide capture: How catalyst-phthalocyanine is leading the way

Addressing the high energy demand of amine-based carbon dioxide capture systems is crucial for achieving carbon neutrality. While enhancing energy efficiency with solid acid catalysts in amine regeneration is promising, developing more efficient catalysts remains a critical challenge. In this study, we introduce the innovative use of a robust, metal-free phthalocyanine as a catalyst to facilitate amine regeneration. Distinctively, phthalocyanine features a macrocyclic ring with an extensive π-conjugated system that functions as Lewis acid sites, diverging from conventional methods that rely on metal atoms for this role. Additionally, the nitrogen and hydrogen atoms on the macrocyclic ring act as Brönsted base sites and Brönsted acid sites, respectively. These sites collectively contribute to a significant acceleration in the CO2 desorption rate, achieving an increase of 1679% at approximately 67 ℃, which far surpasses the performance of previously investigated catalysts. Furthermore, phthalocyanine catalyzes the decomposition of carbamate and protonated monoethanolamine more efficiently than bicarbonate. This research lays the groundwork for next-generation catalysts in amine solvent regeneration of the carbon dioxide capture process.

Economic, Societal, and Environmental Impacts of Available Energy Sources: A Review

The impacts that the available energy sources have had on society, the environment, and the economy have become a focus of attention in recent years, generating polarization of opinions. Understanding these impacts is crucial for rational evaluation and the development of strategies for economic growth and energy security. This review examines such impacts of the main energy resources currently exploited or in development, including fossil fuels, geothermal, biomass, solar, hydropower, hydrogen, nuclear, ocean, and wind energies on society through analysis and comparison. It is essential to consider how high energy demand influences energy prices, the workforce, and the environment and to assess the advantages and disadvantages of each energy source. One significant finding from this review is that the levelized cost of energy (LCOE) may vary substantially depending on the energy source used and show substantial ranges for different applications of the same energy source. Nuclear energy has the lowest LCOE range whereas ocean energy has the highest LCOE range among the nine energy sources considered. Fossil fuels were found to have the most substantial societal impacts, which involved on the positive side providing by far the largest number of jobs and highest tax revenues. However, on the negative side, fossil fuels, biomass, and nuclear energy sources pose the most significant health threats and social well-being impacts on communities and societies compared to other energy sources. On the other hand, solar, ocean and wind energy pose the lowest risk in terms of health and safety, with solar and wind also currently providing a substantial number of jobs worldwide. Regarding environmental consequences, fossil fuels generate the highest greenhouse gas (GHG) emissions and have the highest adverse impacts on ecosystems. In contrast, nuclear, ocean, solar and wind energies have the lowest GHG emissions and low to moderate impacts on ecosystems. Biomass, geothermal and hydropower energy sources have moderate to high ecosystem impacts compared to the other energy sources. Hydropower facilities require the most materials (mainly concrete) to build per unit of energy generated, followed by wind and solar energy, which require substantial steel and concrete per unit of energy generated. The lack of substantial materials recycling causes associated with solar and wind energy sources. All the energies that use thermal power generation process consume substantial quantities of water for cooling. The analysis and comparisons provided in this review identified that there is an urgent need to transition away from large-carbon-footprint processes, particularly fossil fuels without carbon capture, and to reduce the consumption of construction materials without recycling, as occurs in many of the existing solar and wind energy plants. This transition can be facilitated by seeking alternative and more widely accessible materials with lower carbon footprints during manufacturing and construction. Implementing such strategies can help mitigate climate change and have a positive impact on community well-being and economic growth.

Chronic Cadmium Exposure can Alter Energy Allocation to Physiological Functions in the Shrimp Penaeus vannamei.

Environmental stressors in aquatic organisms can be assessed using a bioenergetic approach based on the evaluation of changes in their physiological parameters. We evaluated the chronic effects of cadmium (Cd2+) on the energy balance as well as the survival, growth, metabolism, nitrogen excretion, hepatosomatic index, oxidized energy substrate, and osmoregulation of the shrimp Penaeus vannamei with the hypothesis that the high energy demand related to the homeostatic regulation of Cd2+could disrupt the energy balance and as a consequence, their physiological functions. The shrimp exposed to Cd2+ had higher mortality (30%), directed more energy into growth (33% of energy intake), ingested 10% more energy, and defecated less than control animals. Cd2+ exposure caused a tendency to decrease metabolism and ammonia excretion but did not alter the hepatosomatic index, type of energy substrate oxidized, and the hyperosmorregulatory pattern of the species. The Cd+2 exposure may have induced a trade-off response because there was a growth rate increase accompanied by increased mortality.

Highly Asymmetric CuSA‐Ov‐Ti3c Atomic Sites Catalyst for Unprecedented Solar Hydrogen Generation

AbstractAtomic‐level tailoring of active sites is an efficient strategy for designing high‐performance photocatalysts for clean energy. Asymmetric atomic sites (AAS) like MSA‐Ov‐M2 created through hetero‐metal single atoms (MSA) doping on defect‐rich metal oxides (M2‐Ov‐M2) are favored for better activation of targeted molecules. However, creating AAS typically demands high energy input, hindering their widespread use in photocatalytic H2 production. Furthermore, precise control over surface defects to create AAS remains challenging. Here, CuSA‐Ov‐Ti3c highly asymmetric atomic sites catalyst (HAASC) is constructed by strategically trapping Cu single atoms on high‐index (111) faceted TiO2. This material combines single‐atom catalysis and facet engineering, achieving unprecedented H2 production rates (8.3 mmol h−1 g−1 in pure water and 784.5 mmol h−1 g−1 in water/methanol mixture). Experimental and theoretical analyses reveal CuSA substituting five‐coordinated Ti atoms (Ti5c) next to three‐coordinated (Ti3c) ones, forming CuSA‐Ov‐Ti3c HAAS. HAAS plays multiple roles in i) improving light harvesting, charge‐transfer dynamics, and redox capability of photoexcited electrons; ii) enhanced adsorption and polarization of H2O molecules; iii) facilitating electron transfer from CuSA‐Ov‐Ti3c to H2O molecules, and iv) raising d‐band center toward Fermi level resulting in ≈250‐fold enhanced H2 production than Ti5c‐O‐Ti3c AASC. This work opens new avenues for future structural designs in heterogeneous catalysis for energy‐related applications.

Metabolic flexibility ensures proper neuronal network function in moderate neuroinflammation

Microglia, brain-resident macrophages, can acquire distinct functional phenotypes, which are supported by differential reprogramming of cell metabolism. These adaptations include remodeling in glycolytic and mitochondrial metabolic fluxes, potentially altering energy substrate availability at the tissue level. This phenomenon may be highly relevant in the brain, where metabolism must be precisely regulated to maintain appropriate neuronal excitability and synaptic transmission. Direct evidence that microglia can impact on neuronal energy metabolism has been widely lacking, however. Combining molecular profiling, electrophysiology, oxygen microsensor recordings and mathematical modeling, we investigated microglia-mediated disturbances in brain energetics during neuroinflammation. Our results suggest that proinflammatory microglia showing enhanced nitric oxide release and decreased CX3CR1 expression transiently increase the tissue lactate/glucose ratio that depends on transcriptional reprogramming in microglia, not in neurons. In this condition, neuronal network activity such as gamma oscillations (30–70 Hz) can be fueled by increased ATP production in mitochondria, which is reflected by elevated oxygen consumption. During dysregulated inflammation, high energy demand and low glucose availability can be boundary conditions for neuronal metabolic fitness as revealed by kinetic modeling of single neuron energetics. Collectively, these findings indicate that metabolic flexibility protects neuronal network function against alterations in local substrate availability during moderate neuroinflammation.

STAT5 Is Necessary for the Metabolic Switch Induced by IL-2 in Cervical Cancer Cell Line SiHa.

The tumor cells reprogram their metabolism to cover their high bioenergetic demands for maintaining uncontrolled growth. This response can be mediated by cytokines such as IL-2, which binds to its receptor and activates the JAK/STAT pathway. Some reports show a correlation between the JAK/STAT pathway and cellular metabolism, since the constitutive activation of STAT proteins promotes glycolysis through the transcriptional activation of genes related to energetic metabolism. However, the role of STAT proteins in the metabolic switch induced by cytokines in cervical cancer remains poorly understood. In this study, we analyzed the effect of IL-2 on the metabolic switch and the role of STAT5 in this response. Our results show that IL-2 induces cervical cancer cell proliferation and the tyrosine phosphorylation of STAT5. Also, it induces an increase in lactate secretion and the ratio of NAD+/NADH, which suggest a metabolic reprogramming of their metabolism. When STAT5 was silenced, the lactate secretion and the NAD+/NADH ratio decreased. Also, the expression of HIF1α and GLUT1 decreased. These results indicate that STAT5 regulates IL-2-induced cell proliferation and the metabolic shift to aerobic glycolysis by regulating genes related to energy metabolism. Our results suggest that STAT proteins modulate the metabolic switch in cervical cancer cells to attend to their high demand of energy required for cell growth and proliferation.

MoSSe-graphene based sandwiched nanolayer hybrid as high-performance lithium sulfur-selenium (LiSSe) battery cathodes

Rechargeable lithium batteries have demonstrated highly promising storage of energy systems because of their advantageous characteristics such as high energy density, extended cycle life, increased output power, and improved safety. To meet the ever-increasing high energy demands for powering hybrid and electric vehicles, it is necessary to develop electrode materials that possess high capacity and excellent rate capability. Hence, this work focuses on a MoSSe-Graphene based sandwiched nanolayer hybrid electrode material (MoSSe-Gr) for efficient Lithium-sulfur-selenium batteries applications. The MoSSe-Gr was synthesized through the solvothermal route, and subsequent calcination of the material at 800 °C under an inert atmosphere. Scanning electron microscopy (SEM), X-aray diffratometry (XRD), high-resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman shifts examinations reveal that graphitization of organic solvent from the precursor solution entrapped in the MoSSe interlayer spacing took place during calcination process, forming MoSSe-Graphene hybrid sandwich nanolayers. When employed as a cathodic material in a LiSSe battery, the hybrid sandwiched layers exhibited high-speed charging capability and extended cycle life. Specifically, the MoSSe-Gr material demonstrated a high-rate capability, delivering high capacities of 806.58/100, 668.42/500, 585.83/1000, 409.25/5000, and 284.16/10000 mAh/g/mA/g.

Techno-economic assessment of solar photovoltaic electrification and calcium looping technology as decarbonisation pathways of alumina industry

Aluminium industry stands out as a significant source of CO2 emissions, due partially to the high energy demand of the alumina extraction stage. Accordingly, this study explores the implementation of direct resistive heating of mid-temperature processes in alumina production as an alternative to decrease CO2 emissions. Additionally, two different strategies are evaluated to decarbonize alumina industry: the generation of renewable electricity through solar photovoltaic panels and the integration of a CO2 capture plant based on calcium looping technology. This work comprehends the modelling and sizing of these plants and the assessment of their economic performance through the calculation of their Net Present Value and their respective payback periods. The integration of both strategies into an alumina refinery model reveals that electrification of low and mid-temperature processes yields a 15 % reduction in CO2 direct emissions, whereas calcium looping demonstrates the potential to capture 97 % of emissions with a 7 % energy penalty. Also, economic assessments indicate substantial potential for improvement through in-site electricity generation via solar photovoltaic panels, exhibiting a payback time of 4.5 years. Conversely, the feasibility of a calcium-looping plant is hindered by high capital expenses, necessitating a longer payback period of 19–24 years. Sensitivity analyses underscore the suitability of in-site renewable electricity generation, whereas carbon emission taxes emerge as crucial in incentivizing carbon-neutral processes, with thresholds around 95–125 €/tonne of CO2. Despite potential deviations from real industrial settings, this study provides evidence for environmentally friendly strategies in alumina production that demonstrate limited adverse effects on economic performance.

Mitochondrial Impact of Organophosphate Pesticide-Induced Cardiotoxicity: An In Silico and In Vitro Study.

Organophosphate pesticides are widely used; however, their use is limited due to neurotoxicity and, to a lesser extent, cardiotoxicity in humans. Given the high energy demands of cardiac muscle, which is characterized by a dense population of mitochondria, any damage to these organelles can exacerbate cardiotoxicity. This study aims to elucidate whether the cardiotoxic effects of organophosphate pesticides originate from mitochondrial dysfunction. To investigate this, in silico toxicogenomic analyses were performed using various tools, such as the Comparative Toxicogenomic Database, GeneMANIA, STRING, and Cytoscape. Results revealed that 11 out of the 13 WHO-recommended Class Ia organophosphate pesticides target genes associated with cardiotoxicity. Notably, three of these genes were mitochondrial, with catalase (CAT) being the common differentially expressed gene among parathion, methyl parathion, and phorate. Furthermore, protein-protein interaction analysis indicated a strong association between CAT and superoxide dismutase 2, mitochondrial (SOD2). Subsequently, isolated heart mitochondria were utilized to assess CAT and superoxide dismutase (SOD) activities in vitro. The findings demonstrated that at a concentration of 7.5ng/µL, both methyl parathion and phorate significantly decreased CAT activity by approximately 35%. Moreover, phorate reduced total SOD and SOD2 activities by 17% and 19%, respectively, at the same concentration. In contrast, none of the three organophosphate pesticides induced the opening of the mitochondrial permeability transition pore. These results suggest that the reduction in CAT and SOD2 activities, critical antioxidant enzymes, leads to the accumulation of reactive oxygen species within mitochondria, ultimately resulting in mitochondrial damage. This mechanism likely underlies the observed cardiotoxicity induced by these organophosphate pesticides.

Do oligodendrocytes regulate axonal glucose uptake and consumption?

Neurons have high energy demands. In a recent study, Looser et al. identified oligodendrocyte Kir4.1 as the activity-dependent driver of oligodendrocyte glycolysis that ensures that lactate is supplied to active neurons. Given that oligodendrocyte Kir4.1 also influenced axonal glucose consumption and uptake, oligodendrocytes may play a broader role in neuronal metabolic regulation.

Evidence for metabolism of creatine by the conceptus, placenta, and uterus for production of adenosine triphosphate during conceptus development in pigs†.

In pigs, the majority of embryonic mortality occurs when free-floating conceptuses (embryos/fetuses and associated placental membranes) elongate, and the uterine-placental interface undergoes folding and develops areolae. Both periods involve proliferation, migration, and changes in morphology of cells that require adenosine triphosphate (ATP). We hypothesize that insufficient ATP in conceptus and uterine tissues contributes to conceptus loss in pigs. Creatine is stored in cells as phosphocreatine for ATP regeneration through the creatine-creatine kinase- phosphocreatine pathway. However, the expression of components of this pathway in pigs has not been examined throughout gestation. Results of qPCR analyses indicated increases in AGAT, GAMT, CKM, CKB, and SLC6A8 mRNAs in elongating porcine conceptuses, and immunofluorescence microscopy localized guanidinoacetate N-methyltransferase, creatine kinase M, and creatine kinase B proteins to the trophectoderm of elongating conceptuses, to the columnar chorionic epithelial cells at the bottom of chorioallantoic troughs, and to endometrial luminal epithelium at the tops of the endometrial ridges of uterine-placental folds on Days 40, 60, and 90 of gestation. Guanidinoacetate N-methyltransferase protein is expressed in endometrial luminal epithelium at the uterine-placental interface, but immunostaining is more intense in luminal epithelium at the bottoms of the endometrial ridges. Results of this study indicate that key elements of the pathway for creatine metabolism are expressed in cells of the conceptus, placenta, and uterus for potential production of ATP during two timepoints in pregnancy with a high demand for energy; elongation of the conceptus for implantation and development of uterine-placental folding during placentation.

Sex differences in metabolic adaptation in infants with cyanotic congenital heart disease.

Female infants with congenital heart disease (CHD) face significantly higher postoperative mortality rates after adjusting for cardiac complexity. Sex differences in metabolic adaptation to cardiac stressors may be an early contributor to cardiac dysfunction. In adult diseases, hypoxic/ischemic cardiomyocytes undergo a cardioprotective metabolic shift from oxidative phosphorylation to glycolysis which appears to be regulated in a sexually dimorphic manner. We hypothesize sex differences in cardiac metabolism are present in cyanotic CHD and detectable as early as the infant period. RNA sequencing was performed on blood samples (cyanotic CHD cases, n = 11; controls, n = 11) and analyzed using gene set enrichment analysis (GSEA). Global plasma metabolite profiling (UPLC-MS/MS) was performed using a larger representative cohort (cyanotic CHD, n = 27; non-cyanotic CHD, n = 11; unaffected controls, n = 12). Hallmark gene sets in glycolysis, fatty acid metabolism, and oxidative phosphorylation were significantly enriched in cyanotic CHD females compared to male counterparts, which was consistent with metabolomic differences between sexes. Minimal sex differences in metabolic pathways were observed in normoxic patients (both controls and non-cyanotic CHD cases). These observations suggest underlying differences in metabolic adaptation to chronic hypoxia between males and females with cyanotic CHD. Children with cyanotic CHD exhibit sex differences in utilization of glycolysis vs. fatty acid oxidation pathways to meet the high-energy demands of the heart in the neonatal period. Transcriptomic and metabolomic results suggest that under hypoxic conditions, males and females undergo metabolic shifts that are sexually dimorphic. These sex differences were not observed in neonates in normoxic conditions (i.e., non-cyanotic CHD and unaffected controls). The involved metabolic pathways are similar to those observed in advanced heart failure, suggesting metabolic adaptations beginning in the neonatal period may contribute to sex differences in infant survival.

Effect of creatine supplementation on cognitive function and mood

Background: Creatine, a naturally occurring compound plays a crucial role in cellular energy metabolism, particularly in tissues with high energy demands like muscles and the brain. Beyond its well-established role in physical performance enhancement, recent research has revealed its potential benefits for cognitive functions and mood regulation. This review paper aims to comprehensively analyze the existing literature on creatine supplementation's effects on cognitive functions and mood. State of Knowledge: Findings suggest that creatine supplementation enhances memory, attention, and executive functions, especially under conditions of stress or sleep deprivation. Moreover, it exhibits mood-stabilizing effects, potentially offering relief for symptoms of depression and fatigue. Creatine's ability to augment brain energy metabolism, alongside its neuroprotective properties, underlies its cognitive and mood-enhancing effects. While generally safe, caution is advised, particularly in populations with kidney diseases or those using medications affecting kidney function. Summary: Creatine emerges as a promising adjunct therapy for enhancing cognitive functions and promoting emotional well-being beyond its traditional role in physical performance.The review underscores the need for further research to elucidate the precise mechanisms of creatine's effects and explore its synergistic potential with other cognitive-enhancing supplements.

Properties of Selected Alkali-Activated Materials for Sustainable Development

Abstract Concrete, which is based on the use of Portland cement as a binder, is often used as a structural material in the construction industry. However, the production of cement has a high energy demand. Alkaline-activated systems, for example, have the potential to replace cement with suitable substitutes, and this also puts the raw materials created as by-products from industrial processes to the fore. The presented research focuses on three selected variants, where the goal is to compare key properties from the point of view of material engineering and structural design. Tests of the mechanical properties of the examined materials are carried out and their durability is compared, namely frost resistance, resistance to chemical and de-icing substances and resistance to elevated temperature. As part of the main design criterion of structure, the resulting average compressive strengths of the selected alkali-activated materials ranged from 52.8 to 62.8 MPa.

Stackelberg game based optimal water allocation from the perspective of energy-water nexus: A case study of Minjiang River, China

Energy and water are interdependent. Water is essential for energy production, and energy is indispensable for water processes. This paper develops a Stackelberg game based bi-level multi-objective model for optimal water allocation under uncertainties from an energy-water nexus perspective, which considers energy-related water consumption and water-related energy production. It handles the hierarchical decision-making problem between the river basin authority and the subareas, as well as the tradeoffs between social equality and ecological damage. The upper level of the model makes schemes on water allocation for multiple subareas, and the lower level decides on water allocation for different types of power generation. To generate reasonable and practical strategies for water allocation, ɛ-constraint method and KKT conditions are used. A case study of Minjiang River, China is given to demonstrate the applicability and practicality. Scenarios analysis is also conducted to demonstrate the effectiveness of the model and the effects of the control parameter changes. The results indicate that the river basin authority would allocate larger water resources to the subareas with higher energy demand. It is concluded that the proposed allocation method is advantageous to the subareas with higher water utilization efficiency. The proposed bi-level model demonstrates its reasonableness and superiority to the single-level model. Policy implications are finally provided to support the sustainable development of energy-water nexus.

Global comparison shows that soil bacterial communities in extreme pH soils are more structured by deterministic processes

A major aim of microbial ecology is the search for basic ‘rules’ that dominate variation in microbial communities. An earlier comparison of several soil successional series showed that pH explained variation in the relative importance of stochastic versus deterministic processes in bacterial communities. In neutral pH soils, bacterial communities were more strongly influenced by stochastic processes than in low or high pH soils. Here, we took a broad level approach to attempt a more definitive answer of whether soil pH dominates bacterial community structuring using the global database of 237 samples. The beta-NTI showed that at both a global and continental scale, samples with low pH were dominated by deterministic processes, while in samples at around neutral pH, stochastic processes dominated. At high pH, stochasticity dominated on the global scale, but on several continents, the beta-NTI showed determinism predominating. Overall, it appears that bacterial community structuring is strongly and predictably affected by pH, with the most consistent difference observed between determinism at low pH and stochasticity at neutral pH. There is a need for hypothesis testing to explain why this trend exists. It is possible that at low pH, there is a greater selection for consortia to exploit resources, which leads to more predictable, deterministic combinations of species co-occurring. Additionally, the high energy demands for homeostasis and the constraints from the lack of available nutrient resources may impose greater niche-based competition, resulting in more deterministic community structuring at low pH.

Air quality challenges in Central Asian urban areas: a PM2.5 source apportionment analysis in Dushanbe, Tajikistan.

This work presents the first comprehensive assessment of PM pollution sources in Dushanbe, Tajikistan. A total of 138 PM2.5 samples were collected during 2015-2016 and 2018-2019 and were analyzed through gravimetric, ED-XRF, and multi-wavelength absorption techniques. The results show that PM2.5 concentrations were substantially higher than the European annual limit value and WHO Air Quality Guidelines annual average value, with an average of 90.9 ± 68.5μgm-3. The PMF application identified eight sources of pollution that influenced PM2.5 concentration levels in the area. Coal burning (21.3%) and biomass burning (22.3%) were the dominant sources during the winter, while vehicular traffic (7.7%) contributed more during the warm season. Power plant emissions (17.5%) showed enhanced contributions during the warm months, likely due to high energy demand. Cement industry emissions (6.9%) exhibited significant contribution during the cold period of 2018-2019, while soil dust (11.3%) and secondary sulphates (11.5%) displayed increased contribution during the warm and cold months, respectively. Finally, waste burning (1.5%) displayed the lowest contribution, with no significant temporal variation. Our results highlight the significant impact of anthropogenic activities, and especially the use of coal burning for energy production (both in power plants and for residential heating), and the significant contribution of biomass burning during both warm and cold seasons.

Energy Audit on Coconut Shell Charcoal Briquettes Production, Case Study in PT Tom Cococha, Indonesia

Abstract To increase the competitiveness of Indonesian charcoal briquettes in the global market, the production should be using more efficient energy in order to reduce production cost and getting “green product” label. The first step that can be done is to conduct an energy audit that will help the company to find out the patterns of energy use in its production activities and conduct an analysis to see the energy saving opportunities that can be done. This research aims to conduct an energy audit on the charcoal briquette production process at PT Tom Cococha Indonesia. The production stages which were covered in the auditing are grinding and sieving of the coconut shell charcoal, adhesive mixing, molding, drying, and packaging the product. The result of energy auditing which was conducted in the period of June 22 to 28, 2022, shows that the total energy required for processing coconut shell charcoal into coconut shell charcoal briquettes is 6.00 MJ/kg briquettes. Biomass was the largest energy supplier (42.35% of the total energy required) followed by diesel oil (10.24% of the total energy required), and drying process consumed more than 90% of the total energy required. Due to the high energy demand in the drying stage, a detailed audit has been undertaken on the drying process. There are 2 types of dryer machines which have been used for the drying process. Results of the detailed audit in the drying process shows that the energy required at the drying stage by using a diesel oil-fueled dryer is 3.23 MJ / kg of briquettes with a heat use efficiency rate of 78,6%. As for drying by using a biomass-fueled dryer, it is 3.50 MJ / kg briquettes with a heat use efficiency rate of 76%. According to the findings of a thorough energy audit, the electric motors which were used in the production process have technical efficiency less than 80%. According to the result, energy-saving efforts include implementing an ISO 50001-compliant energy management system and performing regular machine maintenance are strongly recommended to be done.