Abstract CO2 huff and puff (HnP) is widely recognized as an effective strategy for enhancing shale oil recovery. However, a comprehensive understanding of its multi-scale performance in fractured shale reservoirs remains limited. To bridge this gap, this study investigates the enhanced oil recovery (EOR) potential of CO2 HnP, with a particular focus on the influence of fractures. A series of large-diameter core HnP experiments, combined with online nuclear magnetic resonance (NMR) analysis, were conducted to evaluate both the macroscopic production characteristics and microscopic pore-scale mobilization characteristics under with and without fractures conditions. The results demonstrated that the presence of fractures significantly enhances shale oil recovery by increasing the CO2 injection capacity, facilitating expansion, and interconnection of isolated fractures, and promoting deeper CO2 diffusion into shale matrix, thereby improving seepage capacity. Additionally, fractures increase the total recovery rates in micropores and mesopores by 8.59% and 10.26%, respectively, while their effect on macropores is negligible (only a 0.14% increase). These findings suggest that fractures play a crucial role in mobilizing oil within smaller pores. This study provides valuable insights into the mechanisms of CO2 HnP in a matrix-fracture system and highlights the importance of fracture networks in optimizing shale oil recovery.
After the completion of open-pit coal mining, land reclamation is implemented to restore the disturbed eco–hydrological system, for which accurate soil moisture characterization is essential. We evaluated the feasibility and performance of an Auto-Regressive Moving Average (ARMA)-based ground-penetrating radar (GPR) inversion scheme for estimating soil moisture in a reclaimed mine area. GPR data were acquired over a reconstructed three-layer soil profile in a reclaimed open-pit coal mine, and soil moisture content was independently determined using the oven-drying method on core samples. An ARMA model was used to describe the relationship between the GPR reflections and soil electromagnetic properties and to invert the vertical distribution of soil moisture. The ARMA-derived GPR estimates reproduced the measured moisture profile well within the depth interval of 1.4–3.0 m and revealed the clear vertical zonation of soil moisture associated with the engineered layering. Correlation coefficients between the ARMA-inverted GPR estimates and oven-drying measurements ranged from 0.64–0.78 for 0–1.4 m, 0.84–0.93 for 1.4–2.2 m, and 0.98–0.99 for 2.2–3.0 m, indicating that inversion accuracy improves systematically with depth. These results demonstrate that ARMA-based GPR inversion provides a reliable and non-destructive approach for quantifying soil moisture in reclaimed mine soils and offers practical support for monitoring and assessing the effectiveness of reclamation in open-pit coal mining areas.
WEN Shu-jie, XU Chang-yi, HUANG Xiang, HUANG Ying-hao, FU He-lin
[Objective] A method for preparing solidified lightweight red sandstone soil using microbial-induced calcium carbonate precipitation (MICP) technology was proposed for the recycle use of red sandstone residual soil in engineering. A design study was conducted on bio-based solidified lightweight red sandstone soil to investigate the solidification mechanism of the modified material. The effects of expanded polystyrene (EPS) mass content and cementation solution concentration on the strength of the lightweight solidified soil are analyzed. Based on this, the compression failure characteristics of the solidified lightweight red sandstone soil are studied, and its cementation mechanism is validated through both strength analysis and failure characteristics. [Methods] Bacillus pasteurii was selected as the target strain, and cementation solutions with concentrations ranging from 0.5 to 2.0 mol/L were prepared. Solidified lightweight red sandstone soil samples with EPS contents ranging from 0% to 1.125% were prepared. The internal microstructure of the modified red sandstone residual soil was analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, its mechanical properties were evaluated through slow shear tests and uniaxial compression tests. [Results] After MICP treatment, a substantial amount of calcite-type CaCO3 precipitates was generated within the red sandstone residual soil. These CaCO3 crystals formed a continuous and dense cementation network between soil particles, serving as the primary contributor to the strength of the solidified lightweight red sandstone soil. In contrast, only sparse crystal clusters were observed on the surfaces of hydrophobic EPS particles. When the cementation solution concentration was 1.5 mol/L and the EPS content was 0.375%, the solidified lightweight red sandstone soil samples exhibited the optimal performance combination. The compressive strength reached 0.76 MPa, meeting the standard requirement (≥0.6 MPa) for foam lightweight soil. The bulk density was 14.3 kN/m3, representing a 13% reduction compared to the undisturbed soil. Additionally, the internal friction angle and cohesion increased by 39% and 17%, respectively. Failure mode analysis revealed that samples with low EPS content (≤0.375%) exhibited typical brittle shear failure, with cracks propagating in a “Y” shape. In contrast, samples with high EPS content (≥1.125%) showed bulging failure, accompanied by surface spalling and debris detachment. [Conclusions] The combination of microbial solidification technology and EPS lightweight foam soil technology has effectively solidified lightweight red sandstone soil, overcoming the high energy consumption limitations of traditional cement-based solidification methods. A quantitative relationship between “cementation solution concentration, EPS content, and mechanical properties” was established. The proposed optimal mix ratio (1.5 mol/L cementation solution + 0.375% EPS) combines both lightweight characteristics (bulk density of 14.3 kN/m3) and high strength (0.76 MPa). This study provides a low-carbon and environmentally friendly solution for the resource utilization of red sandstone residual soil, demonstrating significant application value in engineering fields such as subgrade filling.
River, lake, and water-supply engineering (General)
China produces a large amount of corn straw after the harvest of staple grains every year. Fodder application of corn straw can reduce the waste of straw resources. Such usage also can guarantee the supply of high-quality coarse fodder for livestock and help the development of husbandry and the increase of production and income of farmers and herdsmen in China. Based on the requirements of livestock for straw feed consumption, the corn straw treatment process engineering was studied, and the overall structure, transmission scheme, and main working components of the corn straw crushing and rubbing filament machine were designed. The equipment was developed with three-dimensional modeling and solid design. Key components were verified through finite element analysis. Finally, a prototype was produced for testing. The experimental results showed that when the moisture content of corn straw was tested to be 20%, the percentage of filamentous straw of the equipment was 97.2%, and the calibrated unit power productivity could reach 82.8 kg/(kW · h). Through experiments, all indicators of the equipment met the relevant technical standards of the straw crushing and rubbing filament machine, providing theoretical basis and technical support for the design of the straw crushing and rubbing filament machine.
Las incursiones en la arquitectura del artista estadounidense Donald Judd fueron una constante en el devenir de su trayectoria. Las investigaciones espaciales con sus objetos específicos y su gran interés por la práctica constructiva lo favorecieron. A través de esta investigación, se presenta uno de esos proyectos arquitectónicos en los que Judd tuvo una participación directa, como fue el pabellón no construido para el Kunsthaus Bregenz. Un proyecto poco conocido cuya definición se vio condicionada por las directrices del arquitecto Peter Zumthor, responsable de la configuración completa de la institución. A partir de ese planteamiento, el estudio parte de la consulta directa del material original conservado en los archivos de la Judd Foundation en Marfa, Texas, y se adentra en las transferencias creativas entre el arte y la arquitectura, en el análisis de una singular propuesta que no llegó a ejecutarse. La excesiva autonomía del diseño de Judd no consiguió adecuarse a los criterios fijados por Zumthor, que acabaría asumiendo la realización del pabellón. Pese al intento frustrado de colaboración, el transcurso del encargo revela los intereses de dos figuras como Judd y Zumthor trabajando en un mismo proyecto, al tiempo que descubre la gestación arquitectónica del Kunsthaus Bregenz.
Engineering design, Architectural engineering. Structural engineering of buildings
Corrugated steel plate shear walls (CSPSWs) have been widely utilized as lateral-resistant and energy-dissipating components in multistory and high-rise buildings. To improve their buckling stability, shear resistance, and energy-dissipating capacity, stiffeners were added to the CSPSW, forming stiffened CSPSWs (SCSPSWs). Evaluating the hysteretic performances of SCSPSWs is crucial for guiding seismic design in engineering practice. In this paper, the dissipated energy values of the SCSPSWs with different parameters were calculated. Based on the obtained dissipated energy values, the elastoplastic design theory of stiffeners was established, and the evaluation of the hysteretic performance of the SCSPSWs was provided. Firstly, a finite element (FE) model for analyzing the hysteretic performance of the SCSPSWs was developed and validated against hysteretic tests of the CSPSW conducted by the authors previously. Subsequently, using the validated FE model, approximately 81 examples of SCSPSWs subjected to cyclic loads were analyzed. Hysteretic curves, skeleton curves, secant stiffness, stress distribution, and out-of-plane displacement were obtained and examined. Results indicate that increasing the bending rigidity of the vertical stiffeners and the thickness of the corrugated steel plates, as well as reducing the aspect ratio of the corrugated steel plates, is beneficial for enhancing the load-carrying capacity, stiffness, and energy dissipation capacity of the SCSPSWs. Finally, the transition rigidity ratio <i>μ</i><sub>0,h</sub> was proposed to describe the hysteretic performances. When the rigidity ratio is <i>μ</i> = 50, dissipated energy values of the SCSPSW could achieve 95% of the corresponding maximum dissipated energy. In engineering practice, hence, it is recommended to use stiffeners with a rigidity ratio of <i>μ</i> ≥ <i>μ</i><sub>0,h</sub> = 50 to ensure desirable energy-dissipating capacity in the SCSPSW.
High entropy alloys (HEAs) were prepared using a vacuum arc melting method. The effect of Mo partially substituting Ni on the crystal structure and corrosion behaviors was studied. The results show that the HEAs exhibited a multiphase complex crystal structure which was composed of a BCC matrix and several intermetallic phases. The HEAs showed good corrosion resistance despite multiphase heterogeneity. But cyclic polarization showed that the HEAs were susceptible to pitting corrosion. Selective corrosion of Cr-depleted phases after polarization tests was attributed to the galvanic corrosion between Cr-depleted and Cr-rich phases. The spontaneous passive films on the HEAs surface were characterized by p-type semiconductor. Existence of Mo element of the HEAs accelerated passivation reaction kinetics, improved the stability of passive film, accordingly, acquired better general and pitting corrosion resistance.
The paper presents a set of equations that stands to the basis of a computer program and to the software themselves, that offers to the user the possibility to automatic draw the arcs used to approximate the representation of a chamfer hexagonal prism. Also, the authors present the way to use software that generates the arcs that approximate hyperbolas resulting on a chamfered hexagonal prism.
Architectural engineering. Structural engineering of buildings, Engineering design
In the field of cancer therapy, inhibiting autophagy has emerged as a promising strategy. However, pharmacological disruption of autophagy can lead to the upregulation of programmed death-ligand 1 (PD-L1), enabling tumor immune evasion. To address this issue, we developed innovative ROS-responsive cationic poly(ethylene imine) (PEI) nanogels using selenol chemistry-mediated multicomponent reaction (MCR) technology. This procedure involved simple mixing of low-molecular-weight PEI (LMW PEI), γ-selenobutylacetone (γ-SBL), and poly(ethylene glycol) methacrylate (PEGMA). Through high-throughput screening, we constructed a library of AxSeyOz nanogels and identified the optimized A1.8Se3O0.5/siPD-L1 nanogels, which exhibited a size of approximately 200 nm, excellent colloidal stability, and the most effective PD-L1 silencing efficacy. These nanogels demonstrated enhanced uptake by tumor cells, excellent oxidative degradation ability, and inhibited autophagy by alkalinizing lysosomes. The A1.8Se3O0.5/siPD-L1 nanogels significantly downregulated PD-L1 expression and increased the expression of major histocompatibility complex class I (MHC-I), resulting in robust proliferation of specific CD8+ T cells and a decrease in MC38 tumor growth. As a result, the A1.8Se3O0.5/siPD-L1 nanogels inhibited tumor growth through self-inhibition of autophagy, upregulation of MHC-I, and downregulation of PD-L1. Designed with dynamic diselenide bonds, the A1.8Se3O0.5/siPD-L1 nanogels showed synergistic antitumor efficacy through self-inhibition of autophagy and prevention of immune escape.
Materials of engineering and construction. Mechanics of materials, Biology (General)
In this paper, a narrowband bandpass filter comprising substrate integrated waveguide (SIW) and spoof surface plasmon polaritons (SSPPs) is proposed, achieving miniaturization and low insertion loss at Ka-band. SIWs and SSPPs exhibit low and high cut-off responses, respectively, which can be combined for filtering functionalities. By designing I-shaped SSPP structures with large effective length, the cut-off frequencies of SIW and SSPPs can be tailed to converge at a certain frequency for the narrowband filter, where the SIW mode functions as a quasi-evanescent mode, and the mode impedance ramps fast. A sharp funnel-shaped transition is designed to connect SIW with a large impedance and 50-<inline-formula> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> microstrip line for low insertion loss and a compact profile. In addition, no transitional SSPP structures are desired in the proposed devices, which further shortens the profile dimension. To verify our design, a hybrid filter at 30 GHz is fabricated and characterized. The measured insertion loss is as low as 1.5 dB, and the 3-dB bandwidth is as narrow as 3%, which shows good consistency with the simulation. The proposed SIW-SSPP device has a low profile of <inline-formula> <tex-math notation="LaTeX">$0.70\,\,\lambda \times 0.38\,\,\lambda $ </tex-math></inline-formula> and may find important applications in frequency division multiplexing.
This study aims to achieve further progress in application performance of polymers in cement-based materials. The objective is to establish the research direction of superplasticizers with ordered micro-sequence via the innovation of synthesis technology and to clarify the correlation between the specific motifs in the microstructures of superplasticizers and the properties of cement pastes. In this study, a novel comb-like polycarboxylate superplasticizer (PCE) was synthesized using isobutenyl polyethylene glycol (IPEG) and hydroxyethyl acrylate (HEA) by atom transfer radical polymerization (ATRP) (defined as A-CPCE). Comb-like PCE with the same molecular weight as A-CPCE was also produced via conventional free radical polymerization (defined as CPCE). The molecular properties of both polymers and the structural motifs of monomers therein were characterized via size exclusion chromatography (SEC), 1H nuclear magnetic resonance (1H NMR), 13C nuclear magnetic resonance (13C NMR) and MATLAB, and furthermore the adsorption behavior of PCE polymers on cement particles was analyzed. Together with the rheological and mechanical properties of cement-based materials, the relationship between micro-sequence distribution and macro-performance of PCEs was investigated. The results showed that the monomer sequence distribution in A-CPCE was AAE and AAA, and the probability of the acid-ether ratio of 4:1 was 16.54%, meaning that relatively uniform polymer species were obtained. The A-CPCE molecules exhibited the smaller hydrodynamic radius (Rh=11.7 nm) and stronger adsorption capacity (maximum was 2.3618 mg·g−1) in cement pastes, which was in good accordance with Langmuir isotherm model and pseudo-second order kinetic model. The dispersing power of PCEs correlated with the specific motifs in the microstructures, thus indicating that A-CPCE enhanced the rheological performances of cement paste and concrete. In addition, the compressive strengths of concrete containing A-CPCE after 3 d, 7 d and 28 d were 16.00 MPa, 28.30 MPa and 52.9 MPa, respectively, which were significantly higher than those of concrete with CPCE.
Materials of engineering and construction. Mechanics of materials
Po-Sen Lin, Olivier Le Roux de Bretagne, Marzio Grasso
et al.
This study aims to evaluate the precision of nine distinct hyperelastic models using experimental data sourced from the existing literature. These models rely on parameters obtained through curve-fitting functions. The complexity in finite element models of elastomers arises due to their nonlinear, incompressible behaviour. To achieve accurate representations, it is imperative to employ sophisticated hyperelastic models and appropriate element types and formulations. Prior published work has primarily focused on the comparison between the fitting models and the experimental data. Instead, in this study, the results obtained from finite element analysis are compared against the original data to assess the impact of element formulation, strain range, and mesh type on the ability to accurately predict the response of elastomers over a wide range of strain values. This comparison confirms that the element formulation and strain range can significantly influence result accuracy, yielding different responses in various strain ranges also because of the limitation with the curve fitting tools.
Nistorac Andreea, Ailenei Eugen Constantin, Isopescu Dorina Nicolina
et al.
The ecological footprint of residential buildings has seen a significant increase due to the permanent desire to improve comfort and aesthetics. The construction and rehabilitation of the existing building stock in accordance with the European standards known as “passive house”, implies the minimization of external energy consumption. Thus, the thermal insulation materials used to reduce heat transfer play an essential role in the effort to reduce the environmental footprint generated by residential buildings. Hemp is an important candidate for making heat-insulating materials. Hemp stems find their use as basic fibres inside non-woven materials used to produce heat-insulating materials with applications in the field of construction or composite materials. The energy balance between the amount of energy saved and that of obtaining heat-insulating materials, as well as the type of raw materials used for their manufacture, is a critical factor for achieving the goal of reducing ecological impact.
Saber Mehrparvar, Christoph Wölper, Rolf Gleiter
et al.
Abstract
Chalcogen bonds are noncovalent interactions and are increasingly coming into focus for the design of complex structures in research areas such as crystal engineering, molecular recognition and catalysis. Conceptionally, chalcogen bonds can be considered as interaction between one σ-hole and one Lewis base center. Herein, we analyze the interaction between bidentate chelating ligands having two nucleophilic centers with one single σ-hole of a chalcogenazole (two-lone-pair/one-σ-hole interactions). Referring to this, we show by quantum chemical calculations and X-ray studies that three bond types are possible: in the first case, a chalcogen bond is formed between the σ-hole and only one of the Lewis base centers. In the second case, a strong bond is formed by one nucleophilic center; the second center provides only a small amount of additional stabilization. In the third case, two equivalent bonds to the σ-hole are formed by both Lewis base centers. According to the calculations, the bifurcated bonds are stronger than simple chalcogen bonds and lead to a more rigid molecular arrangement in the complex.