Volume Coefficient Research Articles

Visualization of caudothalamic groove at expert fetal neurosonography.

To describe the sonographic features of the caudothalamic groove in the third trimester of pregnancy in a group of structurally normal fetuses and to report a small series of cases with abnormal appearance of the caudothalamic groove at antenatal cranial ultrasound. This was an observational study conducted at two fetal medicine referral units in Italy. A non-consecutive cohort of pregnant women with a singleton non-anomalous pregnancy were recruited prospectively and underwent three-dimensional (3D) ultrasound assessment of the fetal brain at 28-32 weeks' gestation. At offline analysis, the ultrasound volumes were adjusted in the multiplanar mode, according to a standardized methodology, until the caudothalamic groove was visible in the parasagittal plane. To evaluate interobserver agreement, two operators were asked independently to indicate if the caudothalamic groove was visible unilaterally or bilaterally on each volume and Cohen's kappa (κ) coefficient was calculated. The digital archives of the two centers were also searched retrospectively to retrieve cases with abnormal findings at the level of the caudothalamic groove on antenatal cranial ultrasound that were confirmed postnatally. A total of 180 non-consecutive cases were included. At offline analysis of the 3D ultrasound volumes, the caudothalamic groove was identified in the parasagittal plane by both operators at least unilaterally in 176 (97.8%) cases and bilaterally in 174 (96.7%) cases. The κ-coefficient for the agreement between the two independent operators in recognizing the caudothalamic groove was 0.89 and 0.83 for one and both hemispheres, respectively. The retrospective search of our archives yielded five cases with an abnormal appearance of the caudothalamic groove at antenatal cranial ultrasound, including two cases of hemorrhage and three cases of cyst. The caudothalamic groove is consistently seen in normal fetuses on multiplanar neurosonography in the third trimester, and abnormal findings in this region may be detected antenatally. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Imaging error reduction in radial cine-MRI with deep learning-based intra-frame motion compensation

Objective.Radial cine-MRI allows for sliding window reconstruction at nearly arbitrary frame rate, promising high-speed imaging for intra-fractional motion monitoring in magnetic resonance guided radiotherapy. However, motion within the reconstruction window may determine the location of the reconstructed target to deviate from the true real-time position (target positioning errors), particularly in cases of fast breathing or for anatomical structures affected by the heartbeat. In this work, we present a proof-of-concept study aiming to enhance radial cine-MR imaging by implementing deep-learning-based intra-frame motion compensation techniques.Approach.A novel network (TransSin-UNet) was proposed to continuously estimate the final-position image of the target, corresponding to end of the frame acquisition. Within the radial k-space reconstruction window, the spatial-temporal dependencies among the sinogram representation of the spokes were modeled by a transformer encoder subnetwork, followed by a UNet subnetwork operating in the spatial domain for pixel-level fine-tuning. By simulating motion-dependent radial sampling with (tiny) golden angles, we generated datasets from 25 4D digital anthropomorphic lung cancer phantoms. The network was then trained and extensively evaluated across datasets characterized by varying azimuthal radial profile increments.Main Results.The method required additional 4.8 ms per frame over the conventional approach involving direct image reconstruction with motion-corrupted spokes. TransSin-UNet outperformed architectures relying solely on transformer encoders or UNets across all the comparative evaluations, leading to a noticeable enhancement in image quality and target positioning accuracy. The normalized root mean-squared error decreased by 50% from the initial value of 0.188 on average, whereas the mean Dice similarity coefficient of the gross tumor volume increased from 85.1% to 96.2% in the investigated cases. Furthermore, the final-positions of anatomical structures undergoing substantial intra-frame deformations were precisely derived.Significance.The proposed approach enables an effective intra-frame motion compensation, offering an opportunity to reduce errors in radial cine-MR imaging for real-time motion management.

Chemical reactions regulated by phase-separated condensates

Phase-separated liquid condensates can spatially organize and thereby regulate chemical processes. However, the physicochemical mechanisms underlying such regulation remain elusive as the intramolecular interactions responsible for phase separation give rise to a coupling between diffusion and chemical reactions at nondilute conditions. Here, we derive a theoretical framework that decouples the phase separation of scaffold molecules from the reaction kinetics of diluted clients. As a result, phase volume and client partitioning coefficients become control parameters, which enables us to dissect the impact of phase-separated condensates on chemical reactions. We apply this framework to two chemical processes and show how condensates affect the yield of reversible chemical reactions and the initial rate of a simple assembly process. In both cases, we find an optimal condensate volume at which the respective chemical reaction property is maximal. Our work can be applied to experimentally quantify how condensed phases alter chemical processes in systems biology and unravel the mechanisms of how biomolecular condensates regulate biochemistry in living cells. Published by the American Physical Society 2024

PERHITUNGAN AWAL IMBUHAN AIRTANAH ALAMI DAERAH ALIRAN SUNGAI CIKAPUNDUNG-GANDOK (KAJIAN PERBANDINGAN)

Groundwater recharge is a crucial factor in determining the permissible groundwater extraction within a watershed. In the Cikapundung watershed, the contribution of groundwater to raw water supply has been continuously declining, prompting a shift from groundwater to surface water usage. This study aims to quantify the groundwater recharge volume and recharge coefficient for each geological formation within the Cikapundung-Gandok watershed, covering an area of 90.4 km², and to compare the results with previous studies. The analysis estimates recharge volumes based on rainfall data from 8 stations around the Cikapundung-Gandok watershed from 2010 to 2019, geological formation data, and alternative recharge coefficients. The difference in recharge volume from previous studies is 393,348 m³/year or 1%. Two formations, Qvu and Qyu, which were not identified in earlier studies, supplement the existing geological dataset. The selected recharge volume for the Cikapundung-Gandok watershed is 33,232,004 m³/year or 1.05 m³/s, with the lowest contribution from the Lava formation (Qyl) at 1,364,504 m³/year or 0.04 m³/s and the highest from the Old Volcanic Product (Qvu) at 14,072,243 m³/year or 0.45 m³/s. The tentative recharge coefficients for each rock formation are as follows: Colluvium (Qc) 30%; Unweathered Old Volcanic Product (Qvu) 20%; Sand Tuff (Qyd) 10%; Lava (Qyl) 25%; Pumiceous Tuff (Qyt) 20%; and Young Volcanic Product (Qyu) 20%. The groundwater recharge data obtained can be used to set groundwater extraction limits and to plan for groundwater management using a conservative approach to ensure long-term sustainability.Keywords: groundwater recharge, recharge coefficient, geological formation, groundwater exploitation, Cikapundung-Gandok Watershed

Association between GDF-15 levels and cardiac morphology and function in cardiac magnetic resonance imaging: insights from UK Biobank data analysis

Abstract Background/Introduction Growth Differentiation Factor-15 (GDF-15) has emerged as a biomarker associated with cardiovascular disease and adverse cardiac outcomes. Cardiac morphology and function, assessed through cardiac magnetic resonance imaging (CMR), are critical indicators of cardiovascular pathology. Understanding the relationship between GDF-15 levels and LV characteristics could provide valuable insights into cardiac pathophysiology and disease progression. Purpose This study aims to investigate the association between GDF-15 levels and cardiac morphology and function, utilizing data from the UK Biobank and CMR. By analyzing various CMR-derived parameters, including LV strain, myocardial mass, LV mass-to-volume ratio, ventricular and atrial volumes, we seek to elucidate the impact of GDF-15 on cardiac structure and function. Methods Data from the UK Biobank, including 2,264 participants, were analyzed. The median age of the analyzed participants was 55 years, with a median BMI of 26.0. Among the participants, 53% were females and 47% were males. CMR-derived variables related to cardiac morphology and function, along with GDF-15 levels, were examined. Multiple linear regression models were constructed to assess the association between GDF-15 levels and cardiac parameters, adjusting for age, sex, and other relevant covariates. Confidence intervals (CI) and p-values were calculated to determine the significance of observed associations. Results Analysis of the UK Biobank data revealed significant associations between GDF-15 levels and specific cardiac parameters (table1). Notably, GDF-15 levels were negatively associated with LV myocardial mass (LVM)(coefficient = -1.146, p = 0.0071), LV end-diastolic volume LVEDV)(coefficient = -3.321, p < 0.0001), LV end-systolic volume (coefficient = -1.876, p < 0.0001), as well as right atrial maximum volume (coefficient = -3.025, p < 0.0001) and minimum volume (coefficient = -1.858, p = 0.0003). In addition, LVM/LVEDV was positively associated with GDF-15 level (p<0.03). However, no significant associations were observed between GDF-15 levels and LV strain parameters, ejection fraction, or left atrial volumes. Conclusion This study provides evidence of a significant association between GDF-15 levels and selected parameters of cardiac morphology and function, as assessed by CMR in the UK Biobank population. These findings suggest a potential role of GDF-15 in modulating specific aspects of cardiac structure, function and left ventricle concentric remodeling warranting further investigation.GDF 15

Prospective Longitudinal Analysis of Physiologic MRI-based Tumor Habitat Predicts Short-term Patient Outcomes in IDH-wildtype Glioblastoma.

This study validates MRI-based tumor habitats in predicting time-to-progression (TTP), overall survival (OS), and progression site in isocitrate dehydrogenase (IDH)-wildtype glioblastoma patients. Seventy-nine patients were prospectively enrolled between January 2020 and June 2022. MRI, including diffusion-weighted and dynamic susceptibility contrast imaging, were obtained immediately post-operation and at three serial timepoints. Voxels from cerebral blood volume and apparent diffusion coefficient maps were grouped into three habitats (hypervascular cellular, hypovascular cellular, and nonviable tissue) using k-means clustering. Pre-defined cutoffs for increases in hypervascular and hypovascular cellular habitat were applied to calculate the habitat risk score. Associations between spatiotemporal habitats, habitat risk score, TTP, and OS were investigated using Cox proportional hazards modeling. Habitat risk score was compared to tumor volume using time-dependent receiver operating characteristics analysis. Progression sites were matched with spatial habitats. Increases in hypervascular and hypovascular cellular habitats and habitat risk scores were associated with shorter TTP and OS (all p < .05). Hypovascular cellular habitat and habitat risk scores 1 and 2 independently predicted TTP (hazard ratio [HR], 4.14; p=.03, HR, 4.51; p=.001 and HR, 10.02; p<.001, respectively). Hypovascular cellular habitat and habitat risk score 2 independently predicted OS (HR, 4.01, p=.003; and HR, 3.27, p<.001, respectively). Habitat risk score outperformed tumor volume in predicting TTP (12-month AUC, 0.762 vs. 0.646, p=.048). Hypovascular cellular habitat predicted progression sites (mean Dice index: 0.31). Multiparametric physiologic MRI-based spatiotemporal tumor habitats and habitat risk scores are useful biomarkers for early tumor progression and outcomes in IDH-wildtype glioblastoma patients.

Mean platelet volume (MPV) and red blood cell distribution width coefficient of variation (RDW_CV) as prognostic markers in community-acquired pneumonia in children: a cross-sectional study

BackgroundCommunity-acquired pneumonia (CAP) is a major global health threat for children, causing numerous hospitalizations and deaths. CAP is a leading cause of mortality in children under five and results in millions of hospital admissions each year. Identifying reliable prognostic markers is crucial. Mean platelet volume (MPV) and red blood cell distribution width coefficient of variation (RDW_CV) are accessible and cost-effective options for prognosis assessment. This study investigates MPV and RDW_CV as prognostic markers in children with CAP.MethodsThis cross-sectional study included 150 children aged 1–15 years diagnosed with CAP upon initial examination and admitted to the hospital. CAP diagnosis was based on clinical symptoms, physical examination, and/or radiographic findings, with hospitalization criteria set for CAP in children. CAP severity was assessed using the Clinical Respiratory Score, categorizing patients into mild, moderate, and severe groups. MPV and RDW_CV were compared among these groups.ResultsAmong the patients, 71 (47.3%) were girls, and 79 (52.7%) were boys. The average hospitalization duration was 6.24 ± 3.82 days, with a median of 5 days. Disease severity distribution was 58 (38.7%) mild, 54 (36.0%) moderate, and 38 (25.3%) severe. Both RDW_CV and MPV were higher in severe cases and in children hospitalized for more than 10 days (P < 0.001). A significant positive correlation was observed between RDW_CV and MPV (r = 0.636, P < 0.001). Mean RDW and MPV values were significantly elevated in children needing ICU admission and those with pleural effusion (P < 0.001). The RDW_CV cutoff was 13.75, with 97.4% sensitivity and 80.4% specificity. The MPV cutoff was 8.25, with 78.9% sensitivity and 69.6% specificity.ConclusionElevated RDW_CV and MPV levels are associated with severe CAP in hospitalized children, providing valuable prognostic insights. RDW_CV is a more precise prognostic indicator than MPV, demonstrating superior predictive value in CAP management.

Study on the friction and wear properties of 7075-T6 aluminum alloy enhanced by milling and ultrasonic impact treatment

This study investigates the effects of milling parameters on the surface friction behavior of 7075-T6 aluminum alloy subjected to ultrasonic impact treatment. A three-dimensional milling and friction-wear model was developed using ABAQUS finite element analysis, examining the influence of milling speed, depth, and feed rate on the coefficient of friction, wear volume, and surface morphology through single-factor experiments. Results indicate that milling parameters affect the friction coefficient in the following order: Vc > f > ap. Specifically, increasing milling speed from 35 m/min to 59 m/min raises the average friction coefficient from 0.305 to 0.387, a 26.88 % increase. At a milling speed of 83 m/min, the friction coefficient and wear volume reach their lowest values of 0.305 and 0.977 mm³, respectively. The wear volume decreases with increasing milling speed and feed rate, while milling depth has a minor effect. The most significant reduction in wear volume, from 5.76 mm³ to 0.977 mm³ (an 83.04 % decrease), occurs as milling speed increases from 35 m/min to 83 m/min. Maximum longitudinal slip during the reciprocating motion primarily occurs at the ends, with both positive and negative peak offsets. Surface damage from 304 stainless steel balls against the 7075-T6 alloy involves adhesive and abrasive wear. At a milling depth of 35 μm, friction-induced compounds in the transfer film mainly consist of Al, C, Fe, Zn, Mg, and Cr.

Ventilation of large section blind headings under conditions of changing ore load size

Relevance. The need to ensure safe working conditions in the working areas of underground mines. Stagnant zones with low air velocities can be formed in large section blind heading behind the ore bulk when ore is shipped by mining machines. There is a possibility of the formation of local gas accumulations and their abrupt removal later in such stagnant zones due to the unsteadiness of accumulation and transfer of gas impurities in a blind heading. A sharp removal of gas will lead to contamination of the load-haul-dump operators’ workplace. Aim. To identify removal of exhaust gases in large section blind headings in conditions of changing ore load size. Objects. Large section blind headings with of complex geometry. Methods. Three-dimensional numerical simulation of unsteady turbulent flow of a gas-air mixture in the Ansys CFX, visualization and analysis of simulation data in the Wolfram Mathematica. Results. The paper presents the results of mathematical modeling of ventilation of large section blind headings of complex geometry under conditions of changing ore load size formed during mining operations by the load-haul-dump machines with an internal combustion engine. It is shown that either a single vortex is formed that ventilates the blind headings space, or a stagnant zone behind the bulk ore, which is characterized by a relatively low intensity of mass transfer. Vortex formation depends on the height of the ore bulk. The authors have obtained the dependences of the change in the average concentration of exhaust gases at the outlet of the blind headings space on the operating time of the machine. They determined the dependence of the correction volume coefficient on the geometric parameters of the blind headings. An analytical model of the removal of gases from the blind headings space under conditions of changing bulk ore volume is obtained. The expression of increment in gas concentration on an operator’s workplace makes it possible to derive formula to find maximum time of load-haul dump operation in a stope such that gas concentration is never higher than maximum allowable concentration.

Prospective longitudinal analysis of imaging-based spatiotemporal tumor habitats in glioblastoma, IDH-wild type: implication in patient outcome using multiparametric physiologic MRI

BackgroundPhysiologic MRI-based tumor habitat analysis has the potential to predict patient outcomes by identifying the spatiotemporal habitats of glioblastoma. This study aims to prospectively validate the cut-off for tumor progression obtained from tumor habitat analysis based on physiologic MRI in ascertaining time-to-progression (TTP) and the site of progression in glioblastoma patients following concurrent chemoradiotherapy (CCRT).MethodsIn this prospective study (ClinicalTrials.gov ID: NCT02613988), we will recruit patients with IDH-wild type glioblastoma who underwent CCRT and obtained immediate post-operative and three serial post-CCRT MRI scans within a three-month interval, conducted using diffusion-weighted imaging and dynamic susceptibility contrast imaging. Voxels from cerebral blood volume and apparent diffusion coefficient maps will be grouped using k-means clustering into three spatial habitats (hypervascular cellular, hypovascular cellular, and nonviable tissue). The spatiotemporal habitats of the tumor will be evaluated by comparing changes in each habitat between the serial MRI scans (post-operative and post-CCRT #1, #2, and #3). Associations between spatiotemporal habitats and TTP will be analyzed using cox proportional hazard modeling. The site of progression will be matched with spatiotemporal habitats.DiscussionThe perfusion- and diffusion-derived tumor habitat in glioblastoma is expected to stratify TTP and may serve as an early predictor for tumor progression in patients with IDH wild-type glioblastoma.Trial registrationClinicalTrials.gov ID: NCT02613988.

Effect of laser shock peening on tribological properties of 55SiMoVA bearing steel

Wear is an important factor limiting the service life of 55SiMoVA bearing steel. In this work, laser shock peening (LSP) technology is used to improve the tribological properties of 55SiMoVA bearing steel, and the corresponding underlying mechanism is systematically discussed. After LSP, the kurtosis (Sku) of surface roughness asperities reduced from 10.355 to 5.488, and no new phase was generated. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis suggested LSP induced the generation of dislocation structures and deformation twins, leading to a decrease in the average grain size and an increase in the fraction of high-angle grain boundaries. Due to the work-hardening and fine-grain strengthening, the microhardness increased by 16.6 %, the maximum residual compressive stress amounted to −793.1 MPa, and the coefficient of friction (COF) and wear volume were significantly reduced. Scanning electron microscopy (SEM) results indicated that the wear mechanism of 55SiMoVA bearing steel before and after LSP was not transformed. However, the abrasive wear and delamination wear of the LSPed specimens were significantly improved, which was mainly attributed to grain refinement, increasing microhardness and constructing a residual compressive stress layer in the subsurface layer of 55SiMoVA bearing steel. During the sliding process, the increase in microhardness limits micro-plowing on the wear surface, and the residual compressive stress inhibits the crack formation and expansion, improving the wear resistance of 55SiMoVA bearing steel.

Study on fluid phase behavior characteristics of low permeability reservoir under different CO2 injection amounts

M reservoir is a low peremeability reservoir located in northwest China. Currently, it faces the problem of difficult water injection, low single well production, and rapid production decline. CO2 flooding technology is considered to be implemented to solve these problems by effectively supplementing formation energy. Considering that the phase behavior of reservoir fluid during CO2 injection and its influence on the development effect are complex, the PVT test experiment of reservoir fluid is carried out to analyze the variation of reservoir fluid properties under different CO2 injection volumes. The experimental results show that the saturation pressure, solution gas-oil ratio, volume coefficient and expansion coefficient of crude oil increase with the increase of CO2 injection, while the viscosity and density of oil continue to decrease. When the CO2 injection amount reaches 32 %, the dissolved gas-oil ratio increases from the original 36.2 m³/m³to 150.2 m³/m³, the viscosity of the formation oil is reduced by about 76 % than before CO2 injection; and the volume of crude oil has expanded to 1.28 times of that without CO2 injection. Moreover, the P-T phase diagram is drawn and the influence of CO2 injection on the distribution of phase regions in the phase diagram and the critical parameters of oil is analyzed. The high pressure physical properties of reservoir fluids at different CO2 injection volumes are obtained, which can provide a good foundation for the study of enhancing oil recovery by CO2 injection in M reservoir.

Investigations of the hybrid laser polishing and high-temperature tribological properties of the 316L stainless steel formed by selective laser melting

In this study, the rough surfaces of additive manufactured parts were polished using an innovative combined treatment of continuous wave (CW) laser and inclined femtosecond (fs) laser techniques. The high-temperature friction and wear performances of the initial surface and the polished surface were investigated. The results indicate that the surface roughness was reduced to 0.21 µm and a fine-grained layer of approximately 25 µm was generated through CW-fs laser polishing. The coefficient of friction and wear volume of the CW-fs laser polished surface showed the most significant reductions of 52.2 % and 88.3 %, respectively, compared to those of initial surface under high-temperature conditions.

Enhancing corrosion and wear resistance of a 7075 aluminum alloy via depositing TC4 coating

Aluminum alloys have been widely used in engineering due to their high strength and low density. However, their poor corrosion and wear resistance have largely limited their application in marine equipment. This study successfully improved the corrosion and wear resistance of a typical 7075 Al alloy by depositing a high-performance TC4 titanium alloy coating using in-house annular laser cladding equipment. Microstructural investigations revealed that the defect-free TC4 coating is metallurgically bonded to the 7075 Al alloy substrate along with excellent bond strength. Electrochemical test results showed that compared to the hot-forged 7075 Al alloy and hot-forged double-phase TC4 bulk alloy, the TC4 coating exhibits superior corrosion resistance due to its net-basket α-single-phase microstructure. Further, wear testing results showed that the coefficient of friction and wear volume of the TC4 coating are far lower than that of 7075 Al alloy. The enhanced wear resistance is closely related to the high hardness of the TC4 coating and its excellent fatigue-wear resistance. Therefore, this work can serve as a reference to improve Aluminum alloys' corrosion and wear resistance by depositing Titanium alloy coatings using the annular laser cladding process, which shall widen the potential applications of Aluminum alloys in marine equipment.

Enhancing the cryogenic performance of superconducting magnet encapsulation resins with hyperbranched polymers: A molecular dynamics simulation and experimental study

Epoxy resin (EP) plays a crucial role in safeguarding superconducting magnets. One of the major concerns related to its usage is its inherent susceptibility to cracking under cryogenic temperatures and the strong electromagnetic forces experienced during the operation of superconducting magnets. In this study, we utilize molecular dynamics (MD)simulation and cryogenic experiments to conduct a comprehensive investigation aimed at gaining a profound understanding of the cryogenic toughening mechanism in hyperbranched polymers-toughened (HBPs) EPs. Five different crosslinking models of EP composites were established by MD simulations. The performance parameters obtained from the MD simulation calculations are highly consistent with the experimental results, which included the glass transition temperature, coefficient of thermal expansion, mechanical properties, free volume and atomic mean square displacement. Moreover, the relationship between structural changes and properties of the MD models was investigated. This research method provides a new avenue of exploration for superconducting magnet encapsulation resin materials.

Impacts of CO2-CH4 Mixed Gas on Property of Formation Oil from the Bohai Oilfield

Mechanism analysis and technical scheme optimization on CO2 displacement and CO2 storage are based on the high-pressure physical properties of CO2-added formation oil. Oil and natural gas samples from the BZ25-1 block in the Bohai oilfield were used to conduct high-pressure physical property experiments to explore the impacts of CO2-CH4 mixed gas on the properties of formation oil. After injecting different amounts of mixed gas, the saturated pressure was measured by constant mass expansion test, the viscosity was measured by falling ball method, the expansion coefficient was measured by gas injection expansion test, and the gas–oil ratio and volume coefficient were obtained by single degassing test. The results show that with gas injection, the saturation pressure and dissolved gas–oil ratio of formation oil increase, the volume coefficient and expansion factor go up, while the oil viscosity reduces. With the increase in gas addition, the properties of formation oil continue to improve, but the increase in improvement becomes flat. With the increase in pressure, the amount of dissolved gas in the formation oil will also increase. High-purity CO2 is more helpful to change the properties of formation oil, while the gas mixed with CH4 is more beneficial to elevate the formation energy. For the BZ 25-1 block, the gas injection amount of about 80 mol% is appropriate and the CO2 purity of 60% can well balance the oil properties improvement and the formation pressure elevation.

C@Ag core-shell structure as lubricating additives towards high efficient lubrication

Efficient cooperative lubrication can be achieved via the introduction of core-shell structure lubricant additives with hard core and soft shell, for obtaining the expected anti-wear performance from the structural changes in the friction process. In this study, C@Ag microspheres with a core-shell structure were prepared by the redox method with carbon spheres as the core and Ag nanoparticles as the shell. Their tribological behaviors as base oil (G1830) additive with different concentrations were investigated in detail. Compared with base oil, the addition of C@Ag particles at 0.5 wt% can reduce the coefficient of friction (COF) and wear volume (Wv) up to 15.5% and 88%, respectively. More importantly, C@Ag particles provide superior lubrication performance to single additive (like carbon sphere (CS) and Ag nanoparticle). C@Ag core-shell particles contribute to the formation of tribo-film by melt bonding of flexible Ag and carbon sphere (CS) toward excellent self-repair performance and high-efficiency lubrication. Hence, core-shell structural nanoparticles with hard-core and soft-shell hold bright future for high-performance lubrication application.

A DFT insight of the electronic, thermodynamic, and thermoelectric properties of RuO2

In this study, we explore the structural, electronic, thermodynamic, and thermoelectric properties of RuO2 using density functional theory. The derived equilibrium structural parameters agree with other theoretical and experimental results. The widely used modified Becke–Johnson (mBJ-GGA) potential is adopted for accurate electronic band gap estimation. To incorporate the effect of the extended orbital of the Ru atom, spin-orbit coupling has been used in combination with the mBJ potential. The investigation of electronic properties revealed an indirect semi-conducting nature with a band gap along the W-L symmetry. The calculated band gaps are 1.685 and 1.658 eV from mBJ and mBJ + SOC, respectively. The dynamical stability is tested and verified by calculating the phonon dispersion curve. We have employed the quasiharmonic approximation-based Gibbs2 package to determine the pressure and temperature-dependent thermodynamical parameters, such as cell volume, Debye temperature, heat capacity, entropy, and thermal expansion coefficient. This study uses the BoltzTraP simulation algorithm to determine the thermoelectric parameters such as the Seebeck coefficient, electrical conductivity, and thermal conductivity.

A study on yield calculation method using suspension power chart in beam pumping systems

Abstract Accurate production prediction plays a crucial role in well fault diagnosis and parameter optimization, significantly contributing to the advancement of oilfield digital construction. This paper focuses on the dynamic analysis of beam pumping machines to establish a calculation model for the power diagram of rod pumping systems. The solution involves employing the finite difference method and Fourier series method, facilitating the transition from the suspension point work diagram to the pump work diagram. The effective stroke of the plunger is determined by analyzing the opening and closing points of the Ver using the maximum curvature analysis method. Subsequently, the leakage and volume coefficients are derived by integrating on-site production data, culminating in the realization of an oil well production calculation method based on the suspension work diagram. The compilation of the pump power chart and oil well production calculation program was executed using QT 6.2.3. Comparative analysis with measured production data revealed an average accuracy of 90.05% using the finite difference method, surpassing the performance of the Fourier series algorithm. The established model not only offers a reliable means of predicting production but also provides valuable technical support for the digital and intelligent applications within the oilfield.

A complex-network-based estimation of the representative elementary volume and equivalent permeability coefficient for fractured rock masses

The determination of the representative elementary volume (REV) and equivalent permeability coefficient (EPC) of fractured rock masses is crucial for studying the hydraulic behaviors of engineering rock masses. The complex network originated from graph theory and represents a rapidly developing interdisciplinary field in the 21st century. In this paper, we propose a novel method that utilizes complex-network-based metrics to estimate the REV and EPC of fractured rock masses. In this method, fractures and their intersections are treated as nodes and edges of a complex network, respectively. We propose a transformation procedure of a discrete fracture network (DFN) into a complex network, and the corresponding algorithms are conducted in MATLAB. Subsequently, we obtain a complex network, and several complex-network-based metrics, such as average degree, average clustering coefficient, and graph density, are calculated using Gephi software. We employ the average degree to estimate the REV size of DFN models, while the coefficient of variation is used to quantitatively assess changes in the average degree of multiple random models. Furthermore, we establish an empirical formula utilizing the average degree, average clustering coefficient, and graph density to estimate the EPC of a large-scale DFN model based on the EPC of a small-scale DFN model. To verify the developed method, we conduct numerical experiments using the MAFIC (Matrix/Fracture Interaction Code) solver within the FracMan software. This enabled us to calculate the EPC, which was then used to determine the REV. The results demonstrate that: (a) the REV size estimated by the average degree aligns with the REV size obtained through numerical simulations for both isotropic and anisotropic DFN models, and (b) the error rates between the average EPC calculated by the empirical formula and that obtained by numerical simulations are within 10%. Thus, the proposed seepage parameter estimation methods are deemed valid.