Maximum Density Research Articles

Maximal heat transfer density from cross‐flow heat exchanger with tapered fins using constructal design method

AbstractTapered fins are widely used in heat sinks cooled by forced convection. In this study, maximal forced convective heat transfer from a set of tapered fins in cross‐flow is investigated based on the constructal design method. The tapering of the fins is done for a three‐fin base‐to‐tip ratio (taper ratio). The first taper ratio is TR = 0.5 (fin base < fin tip), the second taper ratio is TR = 1 (fin base = fin tip, straight fin), and the third taper ratio is TR = 2 (fin base > fin tip). In all these cases, the fin length is constant. The fins are heated at constant surface temperature and they are cooled by cross‐flow. A constant pressure difference pushes the cross‐flow toward the fins. The Bejan number ranges from 105 to 107. The forced convective heat transfer density is maximized from the fins for the three taper ratios, and a comparison between them is carried out. The maximization is conducted by numerical and scale analysis. In the numerical analysis, the pressure‐driven flow equations (continuity, momentum, and energy) are solved by means of the finite volume method. In the scale analysis, two extremes are considered. The first extreme is for TR < 1, and the second extreme is for TR > 1. These two extremes are intersected to find the maximal forced convective heat transfer density. The results obtained from numerical and scale analysis confirmed that the maximal forced convective heat transfer density occurs for straight fins (TR = 1) in the whole range of the Bejan number. The heat transfer density from straight fins (TR = 1) is higher than that of tapered fins (TR = 2) by 45.2%, and it is higher than that of tapered fins (TR = 0.5) by 52.7% at Be = 107.

Empirical Correlation of Hossaena Town Soil Index Properties with California Bearing Ratio (CBR) Values

California bearing ratio (CBR) is a key input factor in pavement structural design that is used to determine character size, the strength of unbound materials, and subgrade soils. The construction of a straightforward and logical regression model to forecast the CBR of unbound materials as a function of the index properties of the material. This work explains the relationship between compaction parameters and Atterberg limit tests. Laboratory test was conducted to get the independent (percent finer, liquid limit, plastic limit, plastic index, maximum dry density and moisture content), and dependent variables (CBR). A statistical package for social science software (SPSS) used to develop the mathematical model both in single and multiple regression. The viability of using multiple linear regression analysis to relate CBR values to soil index features was investigated. In this study, SPSS is used to examine each independent variable's significance individually. The multiple linear regression analysis was used to create the correlation, which had an eighteen-person sample size and a modest determination coefficient of R2 = 0.821. The CBR has good relation with maximum dry density and optimum moisture content compared to other parameters. This model applicable for small structure in the specified soil type, MH.

Revealing multiphase coexistence of R-O-T phases in BaTiO3-CaTiO3-BaSnO3 electroceramics for energy harvesting and storage response with piezo actuation

The (Ba1-xCax)(SnyTi1-y)O3 piezoelectric ceramics (where x=0.016, y=0.024; x=0.032, y=0.048; x=0.048, y=0.072; x=0.064, y=0.096; x=0.08, y=0.12) were designed by conventional solid state reaction method. The crystal structure for the composition of x=0.064 and y=0.096 (abbreviated as BCST-4) possesses the coexistence of non-centrosymmetric rhombohedral-orthorhombic-tetragonal (R-O-T) tri-lattice symmetries at room temperature, as demonstrated by the structural Rietveld refinement, Raman analysis, and temperature dependence of dielectric study. Because of the R-O-T multiphase coexistence, BCST-4 possesses a superior electromechanical and piezoelectric property viz. kp ∼ 0.45, strain ∼ 0.100 %, d33* ∼ 649 pm/V, and an improved d33 ∼ 452 pC/N, which is comparable to commercially available soft PZT ceramics (d33 ⁓ 370 pC/N). For BCST-4 ceramics, an exceptional electrostriction coefficient Q33 ∼ 0.0434 m4/C2 value was attained. The intrinsic piezo-actuation DC strain was observed to be 130 microstrain (με) and 188 με with ε33 and ε31 modes respectively. The BCST-4 ceramic exhibits a maximum output power of 1.03 mW, a power density of 13.5 µW/mm3, a maximum output current of 88 µA, and an open circuit voltage Vpp of 28 V which successfully glowed ‘SPPU’ panel having 40 red commercial light-emitting diodes (LEDs). The energy storage study reveals that BCST-4 ceramics exhibit a maximum energy storage density (Wrec) of 165.87 mJ/cm3 with efficiency (ƞ) 68.00 %. Therefore, the improvement in electrostriction coefficient, piezoelectric charge coefficient, and energy storage response indicates that BCST-4 ceramic has the potential for actuator, energy harvesting, and energy storage applications.

Влияние плотности посадки на личиночное развитие камышовой жабы (Epidalea calamita) (по результатам лабораторных исследований)

The Natterjack toad (Epidalea calamita) is widespread in Europe, but it is reducing in numbers, especially in the north and east of its range. The paper presents the results of studying the effect of initial stocking density on survival, development duration and body length of E. calamita larvae in laboratory conditions. The experiments used containers with the same bottom area (1092 cm2), but with different water levels (14 and 28 cm). Larvae were grown at different stocking densities per unit volume (1–3 larvae/L) of water and per unit area of the bottom (82.4–494.5 larvae/m2). The studied larvae have very high survival rate (90.7–100.0%) and show no differences in this parameter in groups in all variants of cultivation. Animals from the lowest density groups were characterized by the shortest developmental duration. With an increase in the stocking density per unit volume of water and bottom area the larval development duration increased. There was a negative correlation of body length with the initial stocking density per unit volume of water (r=-0.52) and bottom area (r=-0.62). The stocking density per the bottom area affected greater the larval developmental duration and body length of juvenile toads, than the stocking density per unit water volume. The authors note that it is advisable to grow E. calamita larvae in laboratory conditions at maximum stocking density (3 larvae/L and 494.5 larvae/m2), as this allows for a greater number of juvenile toads.

Improving The Geotechnical Properties of Cohesive Soils Using Portland Cement and Some Composite Polymers in A Selected Location in The City of Tanumah / Basrah Governorate – Southern Iraq

Background: The purpose of this research is to ascertain how adding Portland cement and composite polymers, as well as the ideal ratios between them, will affect cohesive soils' geotechnical characteristics. Materials and Methods: A composite polymer was created by combining three polymers—isocyanide, unsaturated polyester, polyvinyl acetate, and thinner—as well as a solvent. Portland cement was added to the soil at a rate of 5% of the sample weight. Different percentages of the weight of the cement supplied to the sample—5, 10, 15, 20, and 25%—were utilized as the composite polymer. Several geotechnical tests were carried out, including compaction, unconfined compressive strength, California bearing ratio, absorption, and Atterberg's limits, to ascertain the ideal amount of polymer for the aim of improvement. Results: The findings show that adding cement at a rate of 5% by weight of the sample and a polymeric mixture at a rate of 15% by weight of cement can improve the cohesive soil's engineering properties. It was found that the maximum dry density, unconfined compressive strength, and California bearing ratio had increased while the values of the optimal moisture content, absorption rate, liquid limit values, and plasticity index had decreased. Conclusion: The composite polymer used in soil improvement not only improves the geotechnical properties and resistance of the soil, but it also efficiently enhances and activates the effectiveness of cement. When 15% of the sample's weight of cement was composed of composite polymers, the soil's engineering attributes increased the most.

Intrinsic Electron Transfer in Heteronuclear Dual‐Atom Sites Facilitates Selective Electrocatalytic Carbon Dioxide Reduction

AbstractThe metal–metal (M1–M2) interactions in heteronuclear dual‐atom catalysts (HNDACs) significantly optimize the electronic properties of the active sites, resulting in the promotion of the reaction kinetics in electrocatalysis. However, the regulation mechanisms in these M1–M2 dual‐atom sites still remain unclear. Herein, the intrinsic electron transfer in Fe–Zn dual‐atom sites are revealed for facilitating electrocatalytic carbon dioxide reduction (ECO2R) to carbon monoxide (CO). The electronegativity difference between the Fe and Zn centers induces the specific electron transfer from Zn to Fe, which regulates the electron structures of the active Zn sites, leading to the optimized reaction pathway of CO2‐to‐CO conversion on these sites. The Fe–Zn HNDAC (FeZnNC) exhibits superior ECO2R performances than the single‐atom Fe/Zn catalysts (FeNC and ZnNC) in the typical H‐cell system, the maximum CO partial current density on FeZnNC reaches more than 3.3 and 1.8 folds of those on FeNC and ZnNC, respectively. More importantly, in a strongly acidic medium (pH = 1), FeZnNC achieves CO Faradaic efficiencies greater than 94% in the current density range of 100–400 mA cm−2. This work uncovers the intrinsic electron transfer at the heteronuclear diatomic sites, providing new insights for the rational design of high‐performance HNDACs toward industrial electrocatalysis.

Partial replacement of sand by fine-grained crushed waste glass along with fly ash stabilization for geotechnical applications in pavement

Natural sand (NS) is one of the most used engineering materials in almost all types of construction worldwide. Considering environmental sustainability, the replacement of natural sand with crushed glass waste (CWG) can provide a solution for both geo-environmental problems of natural sand depletion and waste glass disposal at a time, since sand and glass share almost similar chemical components. This research aimed to investigate the mechanical behaviors of natural sand replaced with fine CWG particles by 5 %, 10 %, 15 %, 20 %, 25 %, 30 %, and 35 % of dry weight. NS-CWG optimum composition was then stabilized by adding Class C fly ash (FA) from 5 to 35 % of NS-CWG to find out the optimum FA content to stabilize NS-CWG. The effects were analyzed through compaction, direct shear, and California Bearing Ratio (CBR) tests. Test results showed that maximum dry density increased, and optimum moisture content decreased due to adding CWG, and a contrasting effect was found after adding FA. 25 % FA significantly stabilized the NS-CWG mixture's strength parameters, such as increased cohesion, angle of internal friction, improved shear strength by 55.67 %, and increased CBR by 44 %. The decreased roundness index and scanning electronic microscopy (SEM) test results further evaluated and supported the improved geotechnical properties of NS + CWG + FA. The findings of the study can be useful in producing recycled materials for constructing road pavements of sustainable transport network development.

Evaluation of an empirical model for predicting the calorific value of biomass briquettes from candlenut shells and kesambi twigs

Biomass briquettes offer a sustainable alternative to conventional fossil fuels, contributing to renewable energy while reducing environmental impact. This research explores the development of biomass briquettes from candlenut shell charcoal (Aleurites moluccanus) and kesambi twigs (Schleichera oleosa), focusing on their physical properties and heating values. Using tapioca as a binder, briquettes were produced with varying ratios: A. Control (90% kesambi twigs + 10% adhesive), B. 3:1 (67.5% kesambi twigs + 22.5% candlenut shell charcoal + 10% adhesive), C. 1:1 (45% kesambi twigs + 45% candlenut shell charcoal + 10% adhesive), and D. 1:3 (22.5% kesambi twigs + 67.5% candlenut shell charcoal + 10% adhesive). The study aimed to optimize briquette composition for maximum density, compressive strength, and calorific value while minimizing moisture, ash, and volatile matter. Results indicated that a higher proportion of candlenut shell charcoal enhanced density, compressive strength, and fixed carbon content, with the highest calorific value exceeding 19 MJ/kg observed in the 1:3 ratio. Additionally, the study evaluated three empirical models for predicting the Higher Heating Value (HHV) of the briquettes, finding the Nhuchhen model to be the most accurate, with an R² value of 0.93, providing a reliable method for predicting calorific value.

Synthesis and electrochemical properties of two cobalt(II) and nickel(II) metal-organic frameworks for excellent performance supercapacitors

Two novel metal-organic frameworks, [Co(HNTB)(bif)]·3H2O·DMA (1) and [(Ni2(μ2O)(HNTB)2(bif)2]·2H2O·2H3O·2DMA (2), were obtained with a tripod-type carboxylic ligand (4,4′,4″-Nitrilotrisbenzoic acid, H3NTB) and a rigid N-donor ligand (2,7-bis(1-imidazoly)fluorene, bif) by solvothermal method. Complex 1 exhibits a 2D layered structure and 2 is a 3D microporous structure with an anionic skeleton. Significantly, their electrochemical tests show that both of them own excellent capacitive performance. Complex 1 has a relatively high specific capacitance (301.2 F g−1 at 1 A g−1) with favorable cycling durability (retained 73.2 % over 3000 cycles). Complex 2 presents a high specific capacitance (329.6 F g−1 at 1 A g−1) with a relatively poor cycling durability (retained 58.9 % over 3000 cycles). Additionally, complex 1 // activates carbon (AC) as an asymmetrical ultra-capacitor exhibits a maximum energy density of 20.9 Wh kg−1 at 800.0 W kg−1 and a high cycle stability (retained 89.2 % over 8000 cycles). Complex 2 // AC owns an energy density of 19.3 Wh kg−1 at 750.0 W kg−1 and a satisfactory cycle stability (retained 88.6 % over 8000 cycles).

Approaches for predicting the soil-water characteristic curves of compacted quartz sand based on particle packing theory

The soil-water characteristic curve (SWCC) is an important basis for describing hydraulic properties, which is closely related to environmental problems such as the migration of toxic substances from groundwater and soil. The SWCC models vary considerably with respect to the void ratio or bulk density. However, the void ratio and bulk density of the same soil change at different depths or positions within a flat space. Accurate simulation or calculation requires a precise SWCC, but measuring every SWCC under each density or void ratio condition is difficult. In this study, two particle packing models, the Kwan model and the modified linear packing density model (MLPDM), were introduced into the van Genuchten (VG) model to predict the SWCC for soil at the minimum void ratio (the maximum dry density). Then, the prediction method of the SWCCs for the same soil with different densities or void ratios was given. A series of laboratory tests using quartz sand mixtures were conducted to verify the accuracy of two extended models (the K-VG model and the M-VG model). For the K-VG model, the average RMSE was 0.020. For the M-VG model, the average RMSE was 0.017. In general, the SWCCs predicted by the two extended models were consistent with the measured values.

A rapid pressureless sintering strategy for LLZTO ceramic solid electrolyte sheets prepared by tape casting

Garnet-type electrolytes are regarded as one of the most promising solid-state electrolytes (SSEs) for lithium-ion batteries due to their potential advantages in terms of energy density, electrochemical stability and safety. To achieve the maximum energy density, it is necessary to ensure that the electrolyte layer is as thin as possible. Nevertheless, thin sheet SSE is more challenging to sinter than pellet due to the greater lithium volatilization from the high surface/volume ratio. Garnet-type SSE (Li6.5La3Zr1.5Ta0.5O12, LLZTO) green tape was prepared by the tape-casting technique. The effects of supporter, sintering temperature and dwell time on the relative density, microstructure and ionic conductivity of thin sheet were investigated. A ceramic SSE sheet with a thickness of 173 μm, a relative density of 97.2 %, an ionic conductivity of 2.02 × 10−4 S/cm at 25 °C and an activation energy of 0.25 eV, was achieved using a rapid pressureless sintering at 1250 °C for 25 min with a MgO supporter. This work offers insights into the practical production of LLZTO sheets.

A vision transformer-based deep transfer learning nomogram for predicting lymph node metastasis in lung adenocarcinoma.

Lymph node metastasis (LNM) plays a crucial role in the management of lung cancer; however, the ability of chest computed tomography (CT) imaging to detect LNM status is limited. This study aimed to develop and validate a vision transformer-based deep transfer learning nomogram for predicting LNM in lung adenocarcinoma patients using preoperative unenhanced chest CT imaging. This study included 528 patients with lung adenocarcinoma who were randomly divided into training and validation cohorts at a 7:3 ratio. The pretrained vision transformer (ViT) was utilized to extract deep transfer learning (DTL) feature, and logistic regression was employed to construct a ViT-based DTL model. Subsequently, the model was compared with six classical convolutional neural network (CNN) models. Finally, the ViT-based DTL signature was combined with independent clinical predictors to construct a ViT-based deep transfer learning nomogram (DTLN). The ViT-based DTL model showed good performance, with an area under the curve (AUC) of 0.821 (95% CI, 0.775-0.867) in the training cohort and 0.825 (95% CI, 0.758-0.891) in the validation cohort. The ViT-based DTL model demonstrated comparable performance to classical CNN models in predicting LNM, and the ViT-based DTL signature was then used to construct ViT-based DTLN with independent clinical predictors such as tumor maximum diameter, location, and density. The DTLN achieved the best predictive performance, with AUCs of 0.865 (95% CI, 0.827-0.903) and 0.894 (95% CI, 0845-0942), respectively, surpassing both the clinical factor model and the ViT-based DTL model (p<0.001). This study developed a new DTL model based on ViT to predict LNM status in lung adenocarcinoma patients and revealed that the performance of the ViT-based DTL model was comparable to that of classical CNN models, confirming that ViT was viable for deep learning tasks involving medical images. The ViT-based DTLN performed exceptionally well and can assist clinicians and radiologists in making accurate judgments and formulating appropriate treatment plans.

High power density redox-mediated Shewanella microbial flow fuel cells

Microbial fuel cells utilize exoelectrogenic microorganisms to directly convert organic matter into electricity, offering a compelling approach for simultaneous power generation and wastewater treatment. However, conventional microbial fuel cells typically require thick biofilms for sufficient metabolic electron production rate, which inevitably compromises mass and charge transport, posing a fundamental tradeoff that limits the achievable power density (<1 mW cm−2). Herein, we report a concept for redox-mediated microbial flow fuel cells that utilizes artificial redox mediators in a flowing medium to efficiently transfer metabolic electrons from planktonic bacteria to electrodes. This approach effectively overcomes mass and charge transport limitations, substantially reducing internal resistance. The biofilm-free microbial flow fuel cell thus breaks the inherent tradeoff in dense biofilms, resulting in a maximum current density surpassing 40 mA cm−2 and a highest power density exceeding 10 mW cm−2, approximately one order of magnitude higher than those of state-of-the-art microbial fuel cells.

Electrochemical Performance of Coal-Based Needle Coke Anode for Lithium Ion Batteries

Lithium-ion capacitors (LICs) with the capability of high energy and high power are considered to be attractive for advanced energy storage applications. However, the design and fabrication of suitable electrode materials with desirab-le properties by a facile approach using cost-effective precursors are still a great challenge. In this work, we have utilized needle cokes, an commercial carbon material with high carbon content and soft carbon structure, as a single carbon source for anode material. A lithium-ion battery fabricated using four kinds of needle cokes exhibits a maximum high energy density of 1357mAhg-1. Systematic characterization analysis demonstrates that unique characteristics of the green coke including large interlayer spacing, turbostratic and disordered microstructures that are composed of surface defects, nanopores or voids, and graphitic domains. That contribute synergistically to the outstanding performance of the needle coke-based LIC. More importantly, anode materials from a single source is an effective way for high value-added utilization of needle coke at the commercial level.

Impact of the feed particle size distribution and its packing characteristics on compression comminution

Due to its lower energy consumption than a conventional grinding circuit, there is an increased interest in the mining industry in the High-Pressure Grinding Rolls (HPGR) technology. Despite the benefits, the high quantity of material required to size the HPGR makes it difficult for new mines to consider this technology. The piston press test has been used at The University of British Columbia to predict the behavior of the HPGR. It is possible to predict energy requirements, size reduction, and throughput by utilizing a small amount of material to size the HPGR. The bulk material’s particle size distribution (PSD) plays an important role in how the particle bed will pack. This study investigates the differences in compressing three different sample PSDs obtained from the same copper ore crushed to −12.5 mm. The first PSD corresponds to the natural distribution resulting from the crusher. The second is created artificially to match the Fuller curve PSD, which theoretically should have the highest packing density. The third corresponds to a truncated feed produced by removing the fines (−300μm) from the natural feed. Tests were performed using a piston-and-die press test apparatus to compress the samples at different force levels. Entirely different behaviors are obtained while compressing the same material with different PSDs. Particularly, the Fuller curve PSD achieves a 31%–40% higher grinding rate than the natural feed, while the truncated feed achieves a 9%–30% higher grinding rate than the natural feed. Differences in the specific energy consumption, grinding efficiency, and final compacted densities highlight the critical influence of feed particle size distribution on the energy usage and generation of fine particles, underscoring the importance of optimizing these parameters for energy-efficient mineral processing. The overall findings indicate that an HPGR feed particle size distribution that matches the Fuller curve and, therefore, has a maximum packing density, results in the most energy-efficient comminution.

Estimating the compacted dry density of gravelly soil with oversized particles

The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio P of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, X, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as P increases from zero up to approximately 0.75. The slope of the X-P relation, (X − 1.0) / P, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by X obtained from the substitution of P into the relevant X-P relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.

Atomically Isolated Pd Sites Promote Electrochemical CO Reduction to Acetate through a Protonation-Regulated Mechanism.

Electrochemical CO reduction reaction (CORR) offers a promising approach for sustainable acetate production, the promotion of which requires the control of multiple protonation steps. This paper describes the synthesis of atomically isolated Pd sites onto Cu nanoflakes to regulate the protonation of key intermediates. The Pd sites with moderate water activation capability are found to enhance the protonation of *CO at the neighboring Cu site to *COH, which is confirmed to be the rate-determining step through kinetic isotope effect studies. The formation of *COH-*CO is therefore promoted. Additionally, the Pd sites would preferentially protonate the C-OH group in *COH-*CO due to the spatial approximability and electronic modulation effects, generating *CCO for the selective formation of acetate. An acetate Faradaic efficiency of 59.5% is achieved at -0.78 V vs reversible hydrogen electrode (RHE), with a maximum partial current density of 286 mA cm-2 at -0.86 V vs RHE. The optimized catalyst also exhibits long-term stability for 500 h at 100 mA cm-2 in a membrane electrode assembly. This work reveals a new promoting mechanism for selective CORR with simultaneous tuning of the structural and electronic properties of the proton-supplying sites.

Two-dimensional XYN3 (X=V, Nb, Ta; Y=Si, Ge): Promising optoelectronic materials in photovoltaic photodetectors

Two-dimensional p-type/intrinsic/n-type (p-i-n) homojunction opens up exciting opportunities for the advancement of next-generation electronic and optoelectronic devices. However, it is urgent to explore superior two-dimensional materials for p-i-n homojunction to enhance optoelectronic performance. Herein, the electronic structures, optical properties of monolayer XYN3 (X=V, Nb, Ta; Y=Si, Ge), and the related p-i-n homojunctions are constructed and investigated systematically based on the framework of density function theory and non-equilibrium Green's function calculations. The electronic structures and optical absorption of these stable monolayers reveal that they show semiconductor characteristic with indirect bandgaps of 1.23∼2.13 eV, which possess strong absorption of visible light. The simulations of the p-i-n homojunctions based on these monolayers highlight that VSiN3 and TaSiN3-based p-i-n junctions possess maximum photocurrent densities of 21.43 and 18.48 A/m2, respectively. Moreover, the photoresponses of VSiN3 and TaSiN3-based p-i-n junctions can reach up to 0.61 and 0.55 A/W, respectively, demonstrating that VSiN3 and TaSiN3-based p-i-n junctions could be the ideal candidates for optoelectronic devices. Our work is expected to pave the way for the realization of 2D p-i-n homojunction optoelectronic devices.

Analysis of dynamic characteristics and influencing factors of CO2 low-permeability coal reservoir sequestration

ABSTRACT Abandoned coal seams can be an important carrier for CO2 geological storage. Considering the gas seepage-diffusion and physical adsorption coupling characteristics in the process of CO2 adsorption and storage in coal and rock, a two-dimensional model of coupled flow-solidity for geological storage of CO2 in low-permeability reservoir with double voids was established by introducing the Zhang Hongbin model algorithm and adding the Klinkenberg effect and the compression effect of the rock skeleton in coal reservoirs in the controlling equation for rock deformation. The coupled flow-solid model was solved by using the PDE equation of COMSOL Multiphics program, and the simulation results difference between the new model and the traditional model in terms of sequestration dynamics were compared. The dynamic characteristic of reservoir gas pressure, formation stress, permeability and sequestration density in the process of CO2 geologic sequestration and injection were analyzed, and the influences of injection pressure and injection well diameter on the amount of CO2 sequestration were explored. The results show that the new model is more reasonable for calculating reservoir gas pressure and permeability compared with the Palmer-Mansoori model (PM model), and can simulate the free-state seepage movement of CO2 in the fracture system as well as its physical adsorption process compared with the single-heavy pore medium model. With continuous CO2 injection, the maximum sequestration density was raised to a limit value of about 1000 kg/m3 after 1 year. The date of reaching the limit of the sequestration volume was advanced by about 45 d when the positive pressure of the injected gas was increased from 10 kPa to 50 kPa. This model can reproduce the main parameters including, when affecting the effect, and realize the calculation of parameters such as CO2 density reaching the limit value, sealing limit day, sealing limit amount, which can provide a theoretical basis for further deep understanding of CO2 geological sealing law and scientific development of gas injection scheme.

Common cocklebur (Xanthium strumarium L.) interference in grain sorghum [Sorghum bicolor (L.) Moench]: the influence of weed and crop density.

The common cocklebur (Xanthium strumarium L.) is an invasive weed species in the Asteraceae family that probably originated in Central or South America but has now spread worldwide, where it infests numerous crop fields, including sorghum. It is also a significant invasive weed in various parts of Ethiopia, including the eastern region. In this study field experiments were conducted to investigate the effect of various densities of sorghum and X. strumarium on their growth and reproductive output at Haramaya and Babile Research Stations of Haramaya University in Eastern Ethiopia during the 2022/2023 growing seasons. Sorghum yield loss was greatly affected by X. strumarium density, reaching maximum yield losses of 79.2% and 93.1% at the maximum weed density at Haramaya and Babile, respectively. The presence of X. strumarium in sorghum resulted in reduced aboveground dry matter and leaf area index (LAI). The extent of this reduction depended on the density of X. strumarium. As crop density increased, X. strumarium dry matter, LAI, and bur production m-2 decreased. The highest bur production per unit area for X. strumarium was observed at its highest density (16 plants m-2) with 1097 and 869 burs per unit area at Haramaya and Babile, respectively. These results indicated that higher densities of sorghum were effective in suppressing the bur production of this weed, leading to reduced yield loss. Therefore, sorghum competitiveness against X. strumarium can be improved using higher crop densities. This could play a key role in weed management by reducing the use of herbicides and mechanical controls, thereby forming an important part of integrated weed management. © 2024 Society of Chemical Industry.