Increase In Moisture Content Research Articles

Evaluation of the Activation Energy for Pyrolytic Degradation of Poly-L-Lactide (PLA) During Artificially Accelerated Aging.

In the course of this study, the pyrolytic degradation characteristics of three poly(lactic acid) (PLA) types were investigated under inert conditions using dynamic thermogravimetric analysis (TGA) across the temperature range of 23°C-600°C with four heating rates. Specifically, the activation energy and its implications were determined at different stages of degradation. For this purpose, a comparative analysis of various isoconversional methods, including Kissinger, Flynn-Wall-Ozawa (FWO), Friedman, and Kissinger-Akahira-Sunnose (KAS) was undertaken to evaluate the reliability of each. The results indicate a decrease in thermal stability, indicated by a shift of the derived mass loss curves to lower temperatures, as confirmed by an increased water content and decreased crystallinity of the test specimen during aging. The study also highlights that if crystallinity and moisture content increase moderately, the thermal degradation curves remain unchanged. Additionally, kinetic analyses using mentioned models indicate a multi-step degradation process of PLA. The activation energy fluctuates with the conversion rate, suggesting complex underlying kinetics. These findings emphasize the need for dynamic adjustment of predictive models for material lifespan. The three PLA types were characterized by Differential Scanning Calorimetry (DSC), moisture absorption measurement and Gel permeation chromatography (GPC).

Experimental study on disintegration of unsaturated red clay in Ca2+ solution environment

Guilin is a world-famous karst area characterized by a high concentration of Ca2+ in its groundwater. The disintegration of red clay plays a key role in the collapse of soil caves. In order to study the disintegration mechanisms of unsaturated red clay in Ca2+ solution, disintegration tests were conducted using a self-made disintegration apparatus. The soil samples are placed on the sieve plate of the disintegration apparatus, and a tensile meter records the real-time change of samples mass to calculate the disintegration rate. XRD analysis and filter paper method were employed to determine the mineral composition and matric suction of red clay, respectively. The results show that the matric suction decreases with increasing moisture content and increases with the void ratio. When the matric suction exceeds 965 kPa, disintegration is markedly intense, and the disintegration rate shows no significant correlation with Ca2+ concentration. When the matric suction is below than 965 kPa, the disintegration rate increases from 0.057 to 3.027 g/s with the increase of Ca2+ concentration. The disintegration of red clay with high matric suction is primarily attributed to the rapid ingress of water molecules and the compression of air due to matric suction, resulting in tensile stress. The disintegration of red clay with low matric suction is primarily caused by the reduction in the diffusion layer thickness of clay particles and the weakening of interparticle attraction due to Ca2+.

Formulasi Sediaan Lip Gel Dari Ekstrak Etanol Kulit Buah Nanas (Ananas comosus (L.) Merr.) Sebagai Pelembab Bibir

Lips are a facial area that is vulnerable to adverse environmental influences, which can lead to discomfort such as dry, chapped lips, and a dull appearance. Lip gels are commonly used in lip care. Pineapple peel waste (Ananas comosus (L.) Merr.) contains compounds that can be utilized for lip care. The objective of this study was to determine the formulation of a lip gel preparation by testing its physical properties, irritation, and effectiveness as a lip moisturizer. This study is an experimental study. Base optimization was carried out, followed by formulation of preparations with pineapple peel extract concentrations of F1=3%, F2=5%, and F3=7%, physical evaluation of the preparation, namely organoleptic tests, homogeneity tests, spreadability tests, adhesiveness tests, viscosity, pH, irritation tests, and moisturizing effectiveness tests. The results showed that pineapple peel extract can be used as an active ingredient in lip gel preparations. The physical properties of the preparations were semi-solid, yellow to brownish in color with a characteristic pineapple aroma, and did not cause irritation or erythema. All formulas were still within the requirements of good characteristics. The lip gel formulation F2 was more effective based on the results of the percentage increase in moisture content, which was 73.18%.

Performance evaluation of lime-improved lateritic soil with the addition of pulverised snail shell and sawdust ash for sustainable highway infrastructure

This research investigated the effects of lime, Pulverized snail shell (PSS), and sawdust ash on the mechanical properties of lateritic soil for soil stabilization in construction. The use of this waste materials aligns with the United Nations’ Sustainable Development Goals (SDGs), particularly Goal 12 on responsible consumption and production and Goal 9 on sustainable infrastructure development. Reusing waste materials for soil stabilization supports a circular economy approach, diverting these materials from landfills and promoting their sustainable use as valuable resources. Various tests, including maximum dry density, moisture content, unconfined compressive strength (UCS), triaxial, permeability, compressibility, and California Bearing Ratio (CBR) tests, were conducted on soil samples with different proportions of additives. The results show that the addition of additives reduced maximum dry density and increased moisture content. The sample with 6% lime and 7.5% PSS exhibited the highest UCS of 302 kPa after 28 days of curing, while the untreated sample had a UCS of 121 kPa. Triaxial tests revealed reduced cohesion and increased angle of internal friction with higher additive content. The 6% lime and 7.5% PSS sample displayed the highest shear strength of 60.6 kPa and elastic modulus of 181.8 MPa. Permeability tests demonstrated that the 6% lime and 6% sawdust ash sample had the lowest permeability (6.67 × 10–7 m/s) among the stabilized samples. The untreated soil exhibited high compressibility, whereas the 6% lime and 7.5% PSS sample exhibited the highest resistance to compression and deformation. The untreated soil had a soaked CBR value of 8%, while the 6% lime and 7.5% PSS sample achieved the highest soaked CBR value of 38%, making it suitable as a sub-base material. These findings highlight the effectiveness of lime, PSS, and sawdust ash in enhancing the mechanical properties of lateritic soil and offer valuable insights for soil stabilization in construction of Sustainable Highway Infrastructure.

Nutritional, Functional, and Microbial Quality of Wheat Biscuits Enriched With Malted Pearl Millet and Orange Peel Flours

ABSTRACTIn this study, composite biscuits were produced by combining wheat flour (WF) with different proportions of malted pearl millet (MPM) flour (8%, 16%, 24%, and 32%) and orange peel (OP) flour (2%, 4%, 6%, and 8%), using 100% WF as a control. The investigation covered the functional properties, viscosity, and thermal properties of the flours, along with the proximate composition, antioxidant, physical properties, color attributes, and microbial quality of the composite biscuits. As MPM and OP flour (OPF) contents increased, water absorption capacity, dispersibility, and foaming power increased, while the viscosities of both hot and cold pastes decreased. The thermal properties of the composite flours, including onset, peak, and final temperatures (ranging between 74.19°C and 100.76°C), showed an upward trend with increasing proportions of MPM and orange peel flour (OPF). There was an increase in moisture content (3.43%–4.93%), ash (4.50%–5.59%), crude protein (11.70%–13.41%), and crude fiber (11.44%–16.24%) of biscuits with the incorporation of MPM and OPF. Similarly, the diameter (4.12–4.60 mm), thickness (9.00–10.00 mm), and hardness (7.53–8.75 N) of the biscuits were increased. Antioxidant properties were evident, with an increased total phenolic content (1.40–3.56 mg GAE/100 g), total flavonoid content (2.91–6.79 mg QUE/100 g), vitamin C (0.79–1.01 mg/g), and ferric reducing antioxidant power (1.78–8.64 mg GAE/g). Conversely, color attributes—L* (31.90), a* (10.82), b* (19.59), hue angle (30.42), and chroma (53.66)—were found to decrease with higher levels of MPM and OPF. Microbial quality showed decreased total counts, coliforms, yeasts, and mold in biscuits containing MPM and OPF. Overall, the inclusion of MPM and OPF enhanced the nutritional quality of the biscuits and could reduce reliance on imported wheat.

Study on laser ablation characteristics of tree obstacles in transmission lines

IntroductionAs a new and efficient method for obstacle removal, laser clearance has promising applications in eliminating tree obstacles in transmission lines. This paper aims to explore various aspects related to the laser ablation of tree obstacles in transmission lines through simulation and experimentation.MethodsThis paper employs simulation and experimentation to test the ignition time, burn-through time, peak temperature, and basic carbonization rate of various types of tree obstacles in transmission lines. Additionally, it analyzes the effects of tree density, laser power, clearance distance, and tree moisture content on laser ablation characteristics.ResultsThe results reveal that different types of tree obstacles exhibit distinct ablation characteristics. With increasing tree density, both the ignition and burn-through times increase, while the peak temperature and basic carbonization rate decrease. Additionally, laser power and clearance distance significantly influence laser ablation behavior. Higher laser energy density results in greater heat flux density, leading to shorter ignition and burn-through times and higher peak temperatures and carbonization rates. Moreover, the tree obstacle with the highest moisture content (58.4%) had the shortest burn-through time of 46.56 s, whereas the one with the lowest moisture content (14.8%) took the longest at 58.41 s, which demonstrates that increased moisture content enhances the laser ablation rate.DiscussionThese findings provide a basis for the application of laser-based tree obstacle removal in power transmission lines. The understanding of how different factors such as tree density, laser power, clearance distance, and moisture content affect the laser ablation process can help in optimizing the laser clearance operations for more efficient removal of tree obstacles in transmission lines.

Effects of Moisture Content and Heat Treatment on the Viscoelasticity and Gelation of Polyacrylonitrile/Dimethylsulfoxide Solutions.

Polyacrylonitrile (PAN) gels create significant obstacles in industrial fiber spinning by forming insoluble networks that compromise solution stability and uniformity. This study investigates the rheological properties of PAN/dimethyl sulfoxide (DMSO) solutions, examining how aging time, moisture content, and polymer concentration affect gelation behavior. Dynamic rheological analysis revealed that both physical and chemical crosslinks play crucial roles in gel formation, with gelation accelerating markedly when moisture content exceeds 3% and aging progresses. Under heat treatment at 80 °C, samples with increased moisture content demonstrated rapid transitions to solid-like states, indicating a critical moisture threshold for enhanced gelation kinetics. Additionally, reductions in polymer concentration disrupted physical crosslink density, thereby mitigating gel formation. These results underscore the importance of precisely controlling moisture and concentration parameters in PAN solutions to stabilize solution properties and minimize gel formation, thus enhancing process efficiency and quality in PAN-based carbon fiber production.

Development of Plant-Based Burgers with Partial Replacement of Texturized Soy Protein by Agaricus bisporus: Effects on Physicochemical and Sensory Properties.

This study aims to develop plant-based burgers with partial replacement of texturized soy protein (TSP) by Agaricus bisporus mushrooms at proportions of 5%, 10%, 15%, and 20%. The substitution was evaluated regarding its impact on the burgers' chemical composition, texture, color, cooking performance, and sensory properties. Chemical analyses showed a significant increase in moisture content starting from the 10% substitution level, contributing to improved juiciness. Protein content remained similar to the control until the 15% substitution level, while the fat content showed no significant variation among treatments. The texture profile indicated reduced hardness in burgers with mushroom enrichment, particularly at 5% and 10%, leading to a more tender product. Color analysis revealed a reduction in lightness (L*) and red intensity (a*) with increased mushroom levels. Sensory analysis showed that burgers with up to a 15% substitution level maintained consumer acceptance comparable to the control, with attributes such as "softness", "pleasant color", and "good appearance" positively correlated with consumer acceptance. The findings indicate that Agaricus bisporus mushrooms can be effectively used as a partial substitute for TSP in plant-based burgers, enhancing sensory properties without compromising quality. This substitution offers a promising approach to diversifying ingredients in plant-based products while maintaining desirable characteristics for consumers.

Determination of the Optimum Moisture Content for the Whole Kernel Recovery During the Cracking Process of Oil Palm Nuts

This study aimed to investigate the effect of moisture content on palm nut cracking and kernel production using a locally fabricated palm nut cracker. Palm nuts of mixed varieties (Dura, Tenera, and Pisifera) were manually cleaned and dried at different moisture content levels ranging from 8.53% to 26.82%. The palm nut cracker is designed with four major units: the in-feed unit, cracking unit, discharge unit and the driving unit. The cracking efficiency was determined by calculating the ratio of completely cracked nuts to the total nuts fed into the hopper. Results show that the whole kernel recovery varies considerably with moisture content and cracking speed. At the lowest moisture content of 8.58%, the whole kernel recovery is generally low across all the cracking speeds. As the moisture content increases, there is a significant improvement in whole kernel recovery at all the cracking speeds. The highest whole kernel recovery was obtained at intermediate moisture contents of around 14% to 18%, and the cracking speeds of 1000 rpm to 1400 rpm. The ANOVA table shows that both the cracking speed and moisture content have a significant effect on whole kernel recovery. Optimizing these parameters could lead to higher whole kernel recovery. However, it is important to note that other factors such as the cultivar of the nut and the equipment used may also affect the whole kernel recovery.

Moisture desorption isotherms and thermodynamic properties of ecalyptus globulus wood

This paper aimed to analyze the moisture desorption isotherms and specific thermodynamic properties of Algerian Eucalyptus globulus wood using the static gravimetric method. The study was conducted at height temperatures and relative humidity levels ranging from 5% to 90%. The desorption isotherms exhibited a sigmoidal shape, categorized as "type II." A suitable "thermodynamic" equation was chosen to describe the desorption isotherms under controlled conditions. The Clausius-Clapeyron relationship was employed to determine the isosteric heat of desorption. The results demonstrated that, for equilibrium moisture content below 4%, the differential enthalpy and entropy decreased exponentially with increasing moisture content. Specifically, the differential enthalpy decreased from 36 kJ/mol to 5 kJ/mol, while the entropy decreased from 76 J/ (mol K) to 13 J/ (mol K). The enthalpy-entropy compensation theory in the desorption reaction was validated by the observed difference between the isokinetic temperature and the harmonic temperature. Moreover, the wood-water desorption process was spontaneous, as confirmed by the negative value of Gibbs free energy (-1690 J/mol). With increasing temperature, the spreading pressure dropped; at 40°C, it was 2.47978 J/m², and at 80°C, it was 0.82328 J/m². Conversely, the rate of increase was 0.11% J/m² per relative humidity as the water activity increased.

Variability of Soil Aggregate Disintegration During Splash Erosion Under Different Circumstances

ABSTRACTThe duration of rainfall is a significant factor in the process of splash erosion. Nevertheless, there is a lack of comprehensive documentation regarding the extent and characteristic of soil aggregate disintegration resulting from raindrop impact during splash erosion. To examine the properties of the aggregate disintegration mechanism during various of splash erosion, three soil samples (S‐1, S‐2, and S‐3 labeled as the organic matter was 19.77, 31.70, and 26.83 g kg−1) were employed to simulated splash erosion under six durations of rainfall (5, 10, 15, 20, 30, and 40 min). Aggregates ranging in size from 1 to 5 mm were utilized in the preparation of test soils for different antecedent moisture contents (3%, 5%, 10%, and 15%). The result demonstrated that the slaking effect, as observed in the fast wetting of the Le Bissonnais method, is attributed to the sudden release of air entering the water, irrespective of the water immersion duration. Upon increasing moisture content, under fast wetting conditions, the mean weight diameter (MWD) values for S‐2 and S‐3 samples increased from 1.25 and 1.31 to 1.85 and 1.61, respectively. Subsequently, at a moisture content of 10%, the MWD decreased to 1.84 and 1.49 for S‐2 and S‐3 samples, respectively. In contrast, S‐1 sample exhibited an increasing trend from 0.34 to 0.93. The sensitivity of aggregates to disintegration from slaking (RSI) decreased by 0.58, 0.43, and 0.29, while mechanical impact (RMI) decreased by 0.23, 0.11, and 0.08 with increasing moisture content, respectively. The rate of splash erosion for the S‐1 sample exhibited an initial increase followed by a subsequent decrease as the duration of rainfall increased. The S‐1 sample, with the lowest organic matter content, exhibited the highest content of microaggregate content (< 0.25 mm) of splashed particles (referring to soil particles transported out of the splash area by raindrops), ranging from 31.62% to 65.57%. The content of macroaggregate (> 0.25 mm) in the residual soil (indicating soil particles that were left in the area affected by splashing) exhibited a gradual reduction as the duration of rainfall increased. As the soil reached saturation, the influence of physicochemical dispersion became more pronounced with the prolonged duration of rainfall. The forces of slaking and physicochemical dispersion predominantly disrupted > 1 mm aggregates, while the destruction of aggregates within the 0.25–1 mm range was insufficient. This study is valuable for understanding the splash erosion process and provides a scientific foundation for the improvement of soil erosion prediction models.

A Comparative Study of Ground Granulated Blast Furnace Slag and Bagasse Ash Incorporation on Enhancing Mechanical Properties of Expansive Soil

Expansive soils swell when wet and shrink when dry, causing differential settlements that can lead to structural failures in roads and buildings. In cases where these soils cannot be avoided, improving their stability is essential. This study investigates the use of two binders, ground granulated blast-furnace slag (GGBS) and bagasse ash (BA), byproducts of steel and sugarcane processing, respectively, to reduce soil swelling and enhance stability by assessing the mechanical behavior of reinforced expansive soil. To evaluate the behavior of reinforced expansive soils, tests such as Atterberg limits, compaction, swelling potential, and direct shear were conducted. Results indicated that as reinforcement levels increased to an optimal threshold (3% GGBS and 12% BA), the optimum moisture content rose, while maximum dry unit weight generally decreased. A 15% increase in moisture content and a 3.16% decrease in maximum dry unit weight were observed with reinforcement. Cohesion decreased by 27% in soaked conditions and 31% in unsoaked, while the angle of internal friction rose by 106% and 111%, respectively, at the maximum reinforcement threshold. These additives also improved shear strength, reduced swelling potential, and lowered plasticity index, shifting the soil behavior from clay-like to silty. The results show that bagasse ash and GGBS effectively enhance soil properties and provide a sustainable solution for soil stabilization in construction.

EFFECTS OF GUM ARABIC ON THE MOISTURE CONTENT AND WATER ABSORPTION OF LATERITIC BRICKS OF VARYING PARTICLE SIZES OF FINE AGGREGATES

The increasing greenhouse gas emissions associated with construction, accounts for 37% global emissions. In mitigating these challenges, the Nigerian Building and Road Research Institute (NBRRI) recommends the use of lateritic bricks due to it's environmental sustainability. To achieve durability and environmental sustainability, Gum Arabic is introduced in laterite soil to improve its properties. The objective of the study is to determine the suitability of Gum Arabic as stabilizer on the moisture content and water absorption capacity of earth bricks of different particle size distributions. Experimental research method was adopted for the study. The particle size distribution of the laterite soil was classified within the ranges 75µm-600µm, and 1.18mm- 4.76mm. Also, the content of the Gum Arabic was proportioned from the range of 0% to 30% partial replacements. Sample bricks were produced and tested at 14, 21 and 28 days curing period. The data collected from the results of the laboratory experiments was analysed using bar charts. The results showed that, particle size distributions for grading fine aggregate suitable for compressed stabilised earth bricks (CSEB) was found to be between 1.18mm-4.76mm considering it low extent of permeability and high durability properties at 28 days curing period. It was concluded that, moisture content influences the rate of water absorption, such that an increase in moisture content consequently increases the rate of water absorption. However, the low extent of water permeability recorded, reduces the water content in the pores of the CSEBs, thereby reducing the extent of expansion and contraction making the GA-based CSEBS to be less brittle and more durable. It was recommended that, when selecting eco-friendly bricks for construction of buildings, Gum Arabic based Compressed Stabilised Earth Bricks (GA-based CSEBs), should be utilised considering its low permeability and durability for particle size ˃ 600µm.

Investigation of the Impact of Moisture in Various States on the Adsorption of CH4, N2, and CO2 by Coal.

To investigate the impact of moisture in various states on the adsorption of CH4, N2, and CO2 by coal, this study conducted isothermal adsorption experiments on dry coal for moisture and on coal with varying moisture content for CH4, N2, and CO2. The results revealed that coal moisture adsorption progresses through four stages: monolayer adsorption, multilayer adsorption, cluster formation, and condensation into free moisture filling pores. The presence of moisture in coal varies across these stages, with its impact on CH4, N2, and CO2 adsorption decreasing as moisture content increases. As the moisture content rises, the adsorption constants (a and b values) progressively decline and eventually level off. Based on differences in coal moisture states, delineated by a relative humidity of 0.50 (corresponding to a moisture content of 2.39% in experimental samples), adsorption potential theory identified low moisture content stages where the monolayer and multilayer adsorption potentials for moisture (E1 = 4.99 kJ/mol, E2 = 39.71 kJ/mol) exceeded those for CH4, N2, and CO2, suggesting competitive adsorption effects. In the high-water content stage, the mesoporous structural fractal dimension D2 of the coal samples was found to be 2.77, nearly reaching 3, as determined through liquid nitrogen adsorption experiments and fractal dimension theory. This suggests that the intricate pore structure leads to water condensation, free water formation, and pore blockage, making it the primary factor influencing the adsorption of CH4, N2, and CO2 in coals, which is inherently linked to the characteristics of coal.

Dielectric Heating Protocol of Three Low Moisture Flours as Affected by Moisture, Temperature and Mass at 2.45 and 5.8 GHz

ABSTRACT Present studies investigate the dielectric properties (dielectric constant and dielectric loss factor) of three low moisture flours (barley, chickpea and wheat) in the moisture content range 2%–10% (w. b.) and temperatures 10°C–60°C at 2.45 and 5.8 GHz. Measurements were taken using cavity perturbation method in conjunctions with Vector Network Analyzer. Results show that dielectric constant and loss factor increased with temperature as well as moisture content both at 2.45 and 5.8 GHz but decreased with increase in frequency. Change in mass of all flours during heating does not affect dielectric properties at both frequencies. A second order regression equation is generated to predict dielectric properties at both frequencies for entire temperature and moisture. Penetration depths of all flours decreased with increase in moisture content and temperature at 2.45 and 5.8 GHz. These studies provide valuable insights to heating protocol of flours in view of recent flours-related disease outbreaks.

Experimental study on axial compressive properties of bamboo scrimber after high temperature

This study examines the uniaxial compressive mechanical properties of after high temperature bamboo scrimber, taking into account the combined effects of temperature, constant temperature duration, and moisture content. A series of 46 uniaxial compression tests were conducted on bamboo scrimber under various conditions to investigate the failure modes after high temperatures. The analysis focuses on the changes in compressive elastic modulus and peak stress of bamboo scrimber parallel and perpendicular to the grain, in relation to temperature, constant temperature duration, and moisture content. The findings reveal that below 180℃, diagonal shear failure and Y-type shear failure are the primary failure modes for specimens parallel to the grain, while diagonal shear failure predominates for specimens perpendicular to the grain. Above 180℃, bond failure and eccentric crushing become the main failure modes for specimens parallel and perpendicular to the grain, respectively. The peak compressive stress decreases significantly beyond 180℃, with a slower decrease observed as moisture content increases. Constant temperature duration has a notable impact on peak stress, with longer durations resulting in lower peak stress at the same temperature. Although temperature has a lesser effect on the elastic modulus compared to peak stress, empirical formulas were derived to establish the relationship between compressive elastic modulus and peak stress reduction coefficient with variations in temperature, constant temperature duration, and moisture content based on the experimental data.

Organoleptic Evaluation of Aonla (Emblica officinalis G.) Nectar during Storage

A research experiment was conducted during the year 2019-20 and 2020-21 in the Fruit and Vegetable Processing Unit Laboratory, Department of Horticulture, College of Agriculture, Gwalior with seven different varieties of aonla viz., NA-4, NA-5, NA-6,NA-7, NA-10, Laxmi and Chakaiya. This study was carried out in a completely randomized design with three replications. It was studied about the preparation of various value added products such as aonla nectar. From the finding it was observed that, the increase in the percentage of acidity, moisture, phenols and fiber content of aonla nectar while total soluble solids and total sugar content was decreased. There was gradual increase in moisture content of aonla nectar prepared with different pulp combination of aonla fruits during storage period. However, total soluble solids, ascorbic acid content decreased with advancement of storage period. Observations were recorded up to storage period of six months at ambient conditions. Laxmi and Chakaiya varieties were found superior with respect to colour, appearance, taste and aroma as well as flavour. As per the organoleptic evaluation the overall acceptability of anola nectar was found significant with the storage intervals of 30, 60, 90 and 120 days.

Moisture-mineral interactions drive bacterial and organic matter turnover in glacier-sourced riparian sediments undergoing pedogenesis

Glacial recession is occurring at unprecedented rates resulting in increased sediment accumulations in some riverine ecosystems providing new mineral surfaces for soil formation. Soils and sediments have an enormous potential to retain carbon (C), predominantly due to sorption to mineral surfaces. However, C persistence may be sensitive to climate-change induced temperature and moisture variations. We coupled ultrahigh resolution organic matter composition classification with bacterial characterization and respiration measurements to test the combined pedogenic effects of temperature (4 vs 20 °C) and moisture (50 vs 100% water-filled pore space) on C turnover in sediments maintained under different mineralogical conditions (illite-amended vs non-amended). Here we show that the inhibition of CO2 emissions from the combined effect of increased moisture content and illite was reflected in the turnover of key molecular signatures, such as the nominal oxidation state of C, often irrespective of temperature. However, shifts in bacterial communities from a coupled moisture-mineral interaction, were temperature-dependent. Our results highlight the importance of moisture in driving mineral-organic interactions and suggest that C in clay-rich, water-saturated sediments is both thermodynamically unfavorable and mineral-protected from microbial consumption.

Deciphering the Intricate Control of Minerals on Deep Soil Carbon Stability and Persistence in Alaskan Permafrost.

Understanding the fate of organic carbon in thawed permafrost is crucial for predicting climate feedback. While minerals and microbial necromass are known to play crucial roles in the long-term stability of organic carbon in subsoils, their exact influence on carbon persistence in Arctic permafrost remains uncertain. Our study, combining radiocarbon dating and biomarker analyses, showed that soil organic carbon in Alaskan permafrost had millennial-scale radiocarbon ages and contained only 10%-15% microbial necromass carbon, significantly lower than the global average of ~30%-60%. This ancient carbon exhibited a weak correlation with reactive minerals but a stronger correlation with mineral weathering (reactive iron to total iron ratio). Peroxidase activity displayed a high correlation coefficient (p < 10-6) with Δ14C and δ13C, indicating its strong predictive power for carbon persistence. Further, a positive correlation between peroxidase activity and polysaccharides indicates that increased peroxidase activity may promote the protection of plant residues, potentially by fostering the formation of mineral-organic associations. This protective role of mineral surfaces on biopolymers was further supported by examining 1451 synchrotron radiation infrared spectra from soil aggregates, which revealed a strong correlation between mineral OH groups and organic functional groups at the submicron scale. An incubation experiment revealed that increased moisture contents, particularly within the 0%-40% range, significantly elevated peroxidase activity, suggesting that ancient carbon in permafrost soils is vulnerable to moisture-induced destabilization. Collectively, this study offers mechanistic insights into the persistence of carbon in thawed permafrost soils, essential for refining permafrost carbon-climate feedbacks.

Direct liquefaction behavior of Shenhua Shangwan coal under CO containing atmosphere

Direct coal liquefaction (DCL) under CO or syngas atmosphere is beneficial to reduce the cost of hydrogen production. Effects of CO on liquefaction process of Shangwan coal were investigated by comparing the liquefaction behavior in three atmospheres of CO, H2, and N2. Then, effects of different CO/H2 ratios and catalysts on the liquefaction process in syngas were investigated. The results indicated that the oil yield under CO atmosphere reached 43.1%, which was 4.2% lower than that under H2, but 10.2% higher than that under N2. The liquefaction performance was further improved by adding the Shenhua 863 catalyst. It is analyzed that CO promoted liquefaction in two ways: water-gas shift reaction and the reaction between CO and organic structures of coal. Through characterization of the products by GC-MS and FT-IR, it was found that CO makes benzenes, aliphatics, and oxygen-containing compounds in liquefied oil simultaneously increased. The effect on functional groups and free radicals concentration in the solid products was not obvious. The experimental results under syngas showed that the highest oil yield, 57.4%, can be obtained in DCL with 20% CO syngas, and further improved by increasing moisture content of coal appropriately. In addition, the Shenhua 863 catalyst had a good catalytic effect on the liquefaction process and also water-gas shift reaction.