Dispersion Coefficient Research Articles

Long-axial field-of-view PET/CT improves radiomics feature reliability.

To assess the influence of long-axial field-of-view (LAFOV) PET/CT systems on radiomics feature reliability, to assess the suitability for short-duration or low-activity acquisitions for textural feature analysis and to investigate the influence of acceptance angle. 34 patients were analysed: twelve patients underwent oncological 2-[18F]-FDG PET/CT, fourteen [18F]PSMA-1007 and eight [68Ga]Ga-DOTATOC. Data were obtained using a 106cm LAFOV system for 10min. Sinograms were generated from list-mode data corresponding to scan durations of 2, 5, 10, 20, 30, 60, 120, 240, 360 and 600s using both standard (minimum ring difference MRD 85 crystals) and maximum acceptance angles (MRD 322). Target lesions were segmented and radiomics features were calculated. To assess feature correlation, Pearson's product-moment correlation coefficient (PPMCC) was calculated with respect to the full duration acquisition for MRD 85 and 322 respectively. The number of features with excellent (r > 0.9), moderate (r > 0.7 and < 0.9) and poor (r ≤ 0.7) correlation was compared as a measure of feature stability. Intra-class heterogeneity was assessed by means of the quartile coefficient of dispersion. As expected, PPMCC improved with acquisition time for all features. By 240s almost all features showed at least moderate agreement with the full count (C100%) data, and by 360s almost all showed excellent agreement. Compared to standard-axial field of view (SAFOV) equivalent scans, fewer features showed moderate or poor agreement, and this was most pronounced for [68Ga]Ga-DOTATOC. Data obtained at C100% at MRD 322 were better able to capture between-patient heterogeneities. The improved feature reliability at longer acquisition times and higher MRD demonstrate the advantages of high sensitivity LAFOV systems for reproducible and low-noise data. High fidelity between MRD 85 and MRD 322 was seen at all scan durations > 2s. When contrasted with data comparable to a simulated SAFOV acquisition, full-count and full-MRD data were better able to capture underlying feature heterogeneities.

A Novel Landfill Liner Material for Solidified Lake Sediment Based on Industrial By-Product and Construction Waste: Engineering Behavior and Cr(VI) Breakdown Characteristics

Engineering sludge, industrial waste, and construction waste are marked by high production volumes, substantial accumulation, and significant pollution. The resource utilization of these solid wastes is low, and the co-disposal of multiple solid wastes remains unfeasible. This study aimed to develop an effective impermeable liner material for landfills, utilizing industrial slag (e.g., granulated blast furnace slag, desulfurized gypsum, fly ash) and construction waste to consolidate lake sediment. To assess the engineering performance of the liner material based on solidified lake sediment presented in landfill leachate, macro-engineering characteristic parameters (unconfined compressive strength, hydraulic conductivity) were measured using unconfined compression and flexible wall penetration tests. Simultaneously, the mineral composition, functional groups, and microscopic morphology of the solidified lake sediment were analyzed using microscopic techniques (X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy + energy dispersive spectroscopy). The corrosion mechanism of landfill leachate on the solidified sediment liner material was investigated. Additionally, the breakdown behavior of heavy metal Cr(VI) within the solidified sediment liner barrier was investigated via soil column model experiments. The dispersion coefficient was computed based on the migration data of Cr(VI). Simultaneously, the detection of Cr(VI) concentration in pore water indicated that the solidified sediment liner could effectively impede the breakdown process of Cr(VI). The dispersion coefficient of Cr(VI) in solidified sediments is 5.5 × 10−6 cm2/s–9.5 × 10−6 cm2/s, which is comparable to the dispersion coefficient of heavy metal ions in compacted clay. The unconfined compressive strength and hydraulic conductivity of the solidified sediment ranged from 4.90 to 5.93 MPa and 9.41 × 10−8 to 4.13 × 10−7 cm/s, respectively. This study proposes a novel approach for the co-disposal and resource utilization of various solid wastes, potentially providing an alternative to clay liner materials for landfills.

Macrotransport of active particles in periodic channels and fields: Rectification and dispersion.

Transport and dispersion of active particles in structured environments, such as corrugated channels and porous media, are important for the understanding of both natural and engineered active systems. Owing to their continuous self-propulsion, active particles exhibit rectified transport under spatially asymmetric confinement. While progress has been made in experiments and particle-based simulations, a theoretical understanding of the effective long-time transport dynamics in spatially periodic geometries remains less developed. In this paper, we apply generalized Taylor dispersion theory to analyze the long-time effective transport dynamics of active Brownian particles (ABPs) in periodic channels and fields. We show that the long-time transport behavior is governed by an effective advection-diffusion equation. The derived macrotransport equations allow us to characterize the average drift and effective dispersion coefficient. For the case of ABPs subject to a no-flux boundary condition at the channel wall, we show that regardless of activity, the average drift is given by the net diffusive flux along the channel. For ABPs, their activity is the driving mechanism that sustains a density gradient, which ultimately leads to rectified motion along the channel. Our continuum theory is validated against direct Brownian dynamics simulations of the Langevin equations governing the motion of each ABP.

Taylor-Aris Dispersion in Nanotubes: Analytical Solution, Effects of Slip and Surface Potential Landscape, and Measurement of the Slip Length.

Taylor-Aris (T-A) dispersion of a solute in a flowing solvent is a fundamental phenomenon in most mass-transfer processes. Despite its significance and numerous applications in microreactors, colloidal transport in confined media, chromatographic separation, and transport in biological tissues, the effect of the slip length and the topology of surface potential landscapes on T-A dispersion in nanostructured channels has not been studied in detail. We propose a novel methodology for molecular dynamics (MD) simulation of T-A dispersion in such systems, derive an analytical expression for the dispersion coefficient in them, and report on the results of extensive MD simulations of the phenomenon in carbon nanotubes and hexagonal carbon nanochannels. By broadening the topology of the surface energy landscape, we vary the slip lengths, making it possible to distinguish between the effects of confinement, the topology of the energy landscape, and the slip length on the T-A dispersion coefficient. It is demonstrated that measuring the T-A dispersion coefficient in laminar flow is a straightforward and reliable approach for estimating the slip length in nanotubes and other nanostructured materials.

Numerical analysis on the fate and transport of TiO2 nanoparticles in fractured porous media: Addressing intrinsic heterogeneities in sorptive mass transfer

The aggregation and slow migration of nanoparticles in aqueous media have caused serious concerns about their fate and impacts in the subsurface environment. Anthropogenic release and distribution of TiO2 nanoparticles (TNP) have immense potential for surface adsorption, occlusion, impregnation, bioaccumulation, and phase partition into various environmental compartments, and the actual risks in their interactions are still unknown. In an attempt to realize the extent of source zone migration of TNP in a fracture-skin-matrix (F-S-M) medium, a numerical model is developed and analyzed for sensitivity of certain features of the flow field. In addition, the sorptive mass transfer is simulated under four characteristic scenarios with varying assumptions pertaining to the intrinsic heterogeneities. The simulation results highlight the non-selective regulatory role of the skin in providing temporary interfacial space for reversible adsorption between the fracture and the matrix as well as in retarding the desorption rate. A preferential detachment of TNP is observed to be favored by the enhanced properties of skin due to the similarity in diffusion and dispersion coefficients. Out of the four scenarios, the two-site model and two-step model simulated the dynamic pore-filling features of adsorption pertaining to the heterogeneities in TNP and F-S-M characteristics. The results demonstrate that the proposed numerical could fairly detect the transition between local equilibrium and dynamic adsorption-desorption cycles that would eventually determine the mass transfer limitations and the extent of elution of TNP along the flow.

Beryllium adsorption from beryllium mining wastewater with novel porous lotus leaf biochar modified with PO43−/NH4+ multifunctional groups (MLLB)

Wastewater produced in beryllium mining seriously affects ecological balance and causes great environmental pressure. We designed a novel porous lotus leaf biochar modified with PO43−/NH4+ multifunctional groups (MLLB) and used it for beryllium(Be) removal from beryllium mining wastewater. Kinetic and thermodynamic experiments showed that the adsorption capacity (Qe) of Be with MLLB from the simulated beryllium mining wastewater could reach 40.38 g kg−1 (35 °C, pH = 5.5), and the adsorption process was spontaneous and endothermic. The dispersion coefficient Kd of Be with MLLB was 2.6 × 104 mL g−1, which proved that MLLB had strong selective adsorption capacity for Be. Phosphoric acid, ammonia, and hydroxyl groups on the MLLB surface would complex with Be to form Be(OH)2 and Be(NH4)PO4 complexation products, which implied that surface complexation and precipitation reactions might co-existed in the adsorption process. The above results showed that MLLB could effectively adsorb Be and prevent beryllium exposure in a beryllium mining process.Graphical

Community attitudes toward tourism and quality of life: a case study of Palangan village, Iran

Community perception is essential for influencing the physical, social, and environmental growth of a region and is key to achieving a high Quality of Life (QOL). Tourism serves as a common means of introducing outsiders to the area where the community lives. Embracing tourism in remote locations like small towns or rural areas can be difficult, and the success of tourism hinges on community attitudes towards it. The community's engagement and approval of tourism are dependent on the benefits such as how tourism improves their QOL in both the short. Therefore, this study aims to explore the local community's perceptions on how tourism influences various aspects of QOL. A survey of 160 households in Palangan Village was conducted to collect primary data, using a conceptual model with 16 indices to evaluate QOL. The findings indicate that the local community generally has a positive perception of the effects of tourism, especially on key QOL components. Civic and generative well-being are considered more significant than other aspects of QOL. Analysis of the data reveals differences in perception across the 16 QOL indices. The highest average ratings were for institutional participation (3.476), quality of employment (3.456), and individual capability (3.203), while the lowest ratings were for standard of living (1.883), social solidarity (2.289), and environmental resource quality (2.725). For instance, the institutional participation index received an average response rating of 3.476. Additionally, the dispersion coefficient index highlighted notable variations in perception, particularly for satisfaction with living conditions (0.488) and standard of living (0.488). Conversely, employment quality (0.360), institutional cooperation (0.385), and freedom of choice had the lowest dispersion coefficients (0.386). Other indices showed moderate levels of dispersion and distribution of perception. In conclusion, these results underscore the significance of community perception in tourism development and its affect on QOL. They also underscore the importance of strategic planning and balanced development to ensure that all aspects of QOL benefit from the expanding tourism sector, leading to a more sustainable and harmonious community.

Temporal and spatial evolution of residual saltwater contamination in coastal subterranean reservoirs

This study numerically investigated the dynamic process of residual saltwater contamination in subterranean reservoirs (aquifer upstream of subsurface physical barrier) for the first time. The results indicated that the groundwater level elevation resulting from subsurface physical barriers induced a small hydraulic gradient in the subterranean reservoir, with residual saltwater convection driven by the density contrast between saltwater and freshwater. This led to persistent inland intrusion of residual saltwater, causing a gradual expansion of the contamination area (i.e., concentration higher than 0.25 g/L) and a decreased area of high-salinity zone. The area of low concentration residual saltwater (0.25 g/L) initially increased and then decreased over time. For large-scale aquifers, the proportion of the maximum contaminated area to the total aquifer area increased from 0.05 to 0.17. Subsequently, the low-concentration saltwater was considered as a relative high-concentration for ambient freshwater, which released salts into the surroundings and the contamination area reduced to 0.0003 at 160000 d. In small-scale aquifers, residual saltwater transport was affected by inland boundary, and the low-concentration saltwater reached inland boundary at approximately 2000 d, which limited its horizontal expansion and resulted in the polluted area reaching an inflection point early relative to large-scale aquifers. The salt transfer from high-concentration residual saltwater to low-concentration saltwater was closely related to aquifer parameters of hydraulic conductivity, dispersivity, and molecular diffusion coefficient. These findings suggest that residual saltwater contamination should not be overlooked when assessing the efficiency of subterranean reservoirs.

Pulsational mode dynamics in the presence of negions

The stability dynamics, of the gravito-electrostatically driven pulsational mode of gravitational collapse (PMGC) excitable in spherically symmetric dust molecular clouds (DMCs), is systematically theorized. It actively incorporates the interplay of dust viscosity, dust charge fluctuation dynamics, and negionic (negative ionic) effects. We take the DMC constitutive electrons, positive ions, and negions as the Boltzmann species (lighter). The negatively charged dust grains behave as viscous fluids (heavier). A generalized linear cubic dispersion equation, involving a new and unique set of multi-factorial dispersion coefficients, results from the applied spherical normal mode treatment in the DMC model. The diverse growth characteristics of the PMGC dynamics are investigated illustratively. It is found mainly that the cloud size, dust charge, equilibrium electronic number density, and equilibrium dust number density play stabilizing roles in the PMGC. However, the dust mass, equilibrium positive ionic number density, equilibrium negionic number density, and dust viscosity play destabilizing roles against self-gravity. The reliability of our study is ensured by the fact that the diversified stabilizing features explored here are consistent with the previous results. The applicability of our study in astrophysical gravity-driven structure formation processes moderated actively with the negionic effects is finally outlined.

Rotational Taylor dispersion in linear flows

The coupling between advection and diffusion in position space can often lead to enhanced mass transport compared with diffusion without flow. An important framework used to characterize the long-time diffusive transport in position space is the generalized Taylor dispersion theory. In contrast, the dynamics and transport in orientation space remains less developed. In this work we develop a rotational Taylor dispersion theory that characterizes the long-time orientational transport of a spheroidal particle in linear flows that is constrained to rotate in the velocity-gradient plane. Similar to Taylor dispersion in position space, the orientational distribution of axisymmetric particles in linear flows at long times satisfies an effective advection–diffusion equation in orientation space. Using this framework, we then calculate the long-time average angular velocity and dispersion coefficient for both simple shear and extensional flows. Analytic expressions for the transport coefficients are derived in several asymptotic limits including nearly spherical particles, weak flow and strong flow. Our analysis shows that at long times the effective rotational dispersion is enhanced in simple shear and suppressed in extensional flow. The asymptotic solutions agree with full numerical solutions of the derived macrotransport equations and results from Brownian dynamics simulations. Our results show that the interplay between flow-induced rotations and Brownian diffusion can fundamentally change the long-time transport dynamics.

High-order solitary waves, fission, hybrid waves and interaction solutions in the nonlinear dissipative (2+1)-dimensional Zabolotskaya-Khokhlov model

The Zabolotskaya-Khokhlov model (ZKm) is a widely used nonlinear model in the fields of sound, ultrasound, and shock waves. The aims of this paper stems from its examination and rectification of earlier results concerning the N-soliton solutions of nonlinear dissipative (2+1)-dimensional ZKm. By recognizing and incorporating the non-zero values of the dispersion coefficient , this study addresses a significant omission in current research. The findings enhance the comprehension of higher-order soliton behaviors, encompassing bifurcation solitons, higher-order breathers, rogue waves, periodic lumps, and their interactions, which are crucial for both theoretical studies and practical applications in areas like nonlinear optics and fluid dynamics. Subsequent detailed numerical simulations are conducted to elucidate the complex behaviors of the obtained solutions. This thorough exploration provides crucial insights into the intricate patterns exhibited by the nonlinear dissipative (2+1)-dimensional ZKm under different conditions, enhancing our understanding of the underlying physical phenomena.

Enhanced Transverse Dispersion in 3D-Printed Logpile Structures: A Comparative Analysis of Stacking Configurations

Three-dimensionally printed logpile structures have demonstrated the tunability of the transverse dispersion behavior, which is relevant in the context of chemical reactor design. The current modeling study aims to further investigate the trade-offs in such structures, extending the range of geometries investigated and addressing the limitations associated with the pseudo-2D nature of previous experiments. The relative transverse dispersion coefficient and pressure drop were determined using computational fluid dynamics simulations in OpenFOAM for structures with different stacking configurations, porosities and scaling of the structures’ unit cell along the secondary transverse axis. The latter could not be varied in previous experiments, but the current results demonstrate that this limitation suppresses vortex shedding in structures with high porosity. These vortices significantly enhance the transverse dispersion. By using a staggered stacking configuration on both transverse axes, an earlier onset of this phenomenon could be realized. Importantly, operation in this regime could be achieved without an equivalent increase in pressure drop, offering a favorable operating trade-off. The findings demonstrate that at low Reynolds numbers, the studied structures consistently outperform randomly packed beds of spheres, highlighting their potential for chemical process intensification.

Dispersion of solute in a packed cylindrical tube with wall reaction

Abstract The study aims to investigate the transport of solute in a packed cylindrical tube, analytically. At the wall, the solute experiences an irreversible chemical reaction of order-one.The combined action of moments method with integral transform technique has been introduced to employ the Gill’s generalized dispersion model. The main goal is to investigate a full time evaluation of various transport coefficients in different superficial flow through porous media together with wall reaction. This study provides a perspective on how porous media influences the migration of solutes in the presence of wall reactions. Exchange coefficient is shown to be solely dependent on wall absorption. In the presence of porosity, wall absorption causes an increase in the advection coefficient's magnitudes; however, the dispersion coefficient exhibits the reverse behavior. Fluid velocity is always suppressed by damping factor, and thus advection and dispersion coefficients both controlled by damping factor. Increase in porosity parameter will reduces the axial concentration distribution. This work could have applications in areas such as groundwater flow, contaminant transport, or chemical reactions within porous materials.&amp;#xD;

Unsteady solute dispersion in large arteries under periodic body acceleration

The present study investigates the effect of periodic body acceleration on solute dispersion in blood flow through large arteries. Transport coefficients (i.e., exchange, convection, and dispersion coefficients) and mean concentration of the solute are analyzed in the presence of wall absorption. The solute is quickly transported to the wall of arteries with a smaller radius, whereas the opposite is true for arteries with a larger radius. In the presence of body acceleration, the amplitude of fluctuations of the convection coefficient K1(t) increases significantly as the radius of the artery increases. In contrast, an opposite scenario exists for the dispersion coefficient K2(t). The solute dispersion process becomes more effective in arterial blood flow as the radius of the artery decreases. More interestingly, in large arteries with body acceleration, the solute is convected, dispersed, and distributed more toward the upstream direction owing to flow reversal during the diastolic phase of pressure pulsation. Note that this important feature of flow reversal is solely due to periodic body acceleration. For an artery with a small radius, under the influence of periodic body acceleration, the mean concentration of solute Cm is the minimum, and more axial spread is noticed in the axial direction. In contrast, an opposite scenario arises in the artery with a large radius. Additionally, the effect of body acceleration on the shear-induced diffusion of red blood cells is discussed in blood flow.

The study of the city of Rudny as a “heat island”

The annual increase in surface air temperatures contributes to climate change. This phenomenon is widespread over the entire surface of the Earth and is typical for any point of the planet. The purpose of this study was to identify patterns of changes in meteorological indicators in the city of Rudny, Kostanay region, Republic of Kazakhstan over the summer period 2018–2022. The scientific novelty of the work lies in the fact that for the first time the spatial distribution of the heat index in the territory of the city of Rudny was determined. To conduct the study, data from local automated weather stations were used, meteorological data was analyzed, compared for each year of the study, and the heat index was calculated. The reliability of the results is ensured by mathematical processing of daily empirical temperature and humidity data (calculation of the average for the day, the average for the month), coefficient of variation, coefficient of dispersion. The conducted research provides a clear description of climate changes in the city of Rudny, which can be used by municipal authorities to form measures to reduce the thermal impact on public health, heat loss in the housing and communal services system, and to improve air quality when planning urban infrastructure in the territory of the studied city.

Ultrasound viscoelastic imaging in the noninvasive quantitative assessment of chronic kidney disease

Background This study aims to evaluate the clinical application value of ultrasound viscoelastic imaging in noninvasive quantitative assessment of chronic kidney disease (CKD). Methods A total of 332 patients with CKD and 190 healthy adults as a control group were prospectively enrolled. Before kidney biopsy, ultrasound viscoelastic imaging was performed to measure the mean stiffness value (Emean), mean viscosity coefficient (Vmean), and mean dispersion coefficient (Dmean) of the renal. CKD patients were divided into three groups based on estimated glomerular filtration rate. The differences in clinic, pathology, ultrasound image parameters between the control and patient groups, or among different CKD groups were compared. The correlation between viscoelastic parameters and pathology were analyzed. Results Emean, Vmean, and Dmean in the control group were less than the CKD group (p < 0.05). In the identification of CKD from control groups, the area under curve of Vmean, Dmean, Emean, and combining the three parameters is 0.90, 0.79, 0.69, 0.91, respectively. Dmean and Vmean were increased with the decline of renal function (p < 0.05). Vmean and Dmean were positively correlated with white blood cell, urea, serum creatinine, and uric acid (p < 0.05). Vmean is positively correlated with interstitial fibrosis and inflammatory cell infiltration grades (p < 0.001). Conclusions Ultrasound viscoelastic imaging has advantages in noninvasive quantitative identification and evaluating renal function of CKD. Emean > 6.61 kPa, Vmean > 1.86 Pa·s, or Dmean > 7.51 m/s/kHz may suggest renal dysfunction. Combining Vmean, Dmean, and Emean can improve the efficiency of identifying CKD.

Magnetic reduction of gas back-mixing in bubbling fluidized beds with Geldart-B magnetizable particles

This study investigated the performance of magnetic fields in reducing gas back-mixing in bubbling fluidized beds with Geldart-B magnetizable particles. The Peclet number (Pe) and axial dispersion coefficient (Da,g) were determined using the one-dimensional dispersion model. A weak magnetic field reduced gas back-mixing to a certain extent, while a moderate field resulted in minimal decrease. The performance of a strong magnetic field varied significantly depending on the operation mode. Under the magnetization-FIRST operation mode, gas back-mixing was significantly reduced. The corresponding Pe and Da,g were calculated as ∼76 and ∼3.6 × 10−4 m2/s, indicating that the gas flow approached the ideal plug-flow manner. However, when the magnetization-LAST operation mode was used, the strong magnetic field failed to mitigate gas back-mixing. Therefore, the performance of magnetic fields in reducing gas back-mixing depended not only on their intensity but also on their application sequence to the gas flow field.

Exploring Ion Polarizabilities and Their Correlation with van der Waals Radii: A Theoretical Investigation.

Polarizability (α) is a fundamental property which measures the tendency of the electron cloud of an atom, ion, or molecule to be distorted by electric field. Polarizability contributes to important physical properties such as molecular interactions or dielectric constants; thus, it is essential to have accurate polarizabilities in molecular simulations. However, it remains a challenge to develop polarizable force fields (FFs) for ions in computational chemistry. In particular, a comprehensive set of polarizabilities for ions has not been derived. Herein, we derived a systematic set of polarizabilities for atoms and ions across the periodic table based on high-level quantum mechanics calculations. These values have excellent agreement with experimental data. Furthermore, we examined the relationship between the obtained polarizabilities and the van der Waals (VDW) radii (RVDW) that we previously determined (J. Chem. Theory Comput., 2023, 19, 2064). Two relationships, RVDW ∝ α1/7 and RVDW ∝ α1/3, proposed in previous studies were examined in the present work. Our results indicated the former relationship, which was derived based on the quantum harmonic oscillator model, prevails for atoms and cations, but neither relationship provides a satisfactory fit for anions. This is consistent with the tight-binding nature of the electrons in atoms and cations, while it is more challenging to quantify the polarizabilities of anions because of their more dispersed electron clouds. Moreover, we compared different approaches to determine the dispersion coefficients, including the London equation, Slater-Kirkwood equation, symmetry-adapted perturbation theory (SAPT) calculations, and time-dependent density functional theory method, along with the approach based on VDW constants. Our results indicated that although different approaches predict deviated magnitudes for the dispersion coefficients, their predictions are highly correlated, implying that each of these approaches can be used to evaluate dispersion interactions after proper scaling. Finally, we have developed a parametrization strategy for the 12-6-4 model based on the obtained insights. We specifically compared the performance of the 12-6-4 model with SAPT and SobEDA analyses to model interactions involving Na+/Mg2+ and various ligands containing He, Ne, Ar, H2O, NH3, [H2PO4]-, and [HPO4]2-. Our results demonstrate that the 12-6-4 parameters effectively reproduce both the total interaction energy and the individual energy components (electrostatics, exchange-repulsion, dispersion, and induction), highlighting the physical robustness of the 12-6-4 model and the effectiveness of our parametrization approach. This study has significant implications for advancing the development of next-generation ion models and polarizable FFs.

Three-dimensional solute transport in finite and curved porous media with surface input sources

In this paper, an analytical solution for three-dimensional solute transport in porous media between two curved surfaces is investigated. It is assumed that the groundwater velocity and dispersion coefficient vary with time and position. Groundwater velocity is not considered to be horizontal. The components of dispersion coefficient along the axes are considered to be proportional to the square of corresponding the position variable. The dispersion coefficient components along axes are proportional to the corresponding component of groundwater velocity in temporal aspects while former is squarely proportional to letter one in position components. It is assumed that the sources originate from two curved surfaces. The nature of the source on the two surfaces is the same, but there may be a variation in potential. Initially, the aquifer's domain is supposed to be uniformly polluted. The Laplace Integral Transformation Technique (LITT) is used to obtain analytical solutions. Numerical examples are given to demonstrate the effects of various factors on the solute concentration profile in a system where advection and dispersion play important roles.In addition, the sub-case of horizontal flow is also discussed. The model is extremely useful in analyzing and dealing with widespread surface sources of groundwater pollution in simulated agricultural fields or urban dumping areas.

Clinical value of multiparameteric quantitative ultrasound for assessing high-risk steatohepatitis

Objective: To investigate the clinical value of multiparameteric quantitative ultrasound combined with a non-invasive prediction model for assessing high-risk steatohepatitis. Methods: One hundred and ninety-four cases with metabolic-associated fatty liver disease (MAFLD) who underwent liver biopsy in Huashan Hospital, Fudan University, from June 2021 to September 2022 were selected. Shear wave elastography (SWE), shear wave dispersion (SWD) imaging, and attenuation imaging (ATI) examinations were conducted in all patients before biopsy. High-risk steatohepatitis was defined as a total activity score of ≥4 in patients with steatohepatitis, hepatocellular ballooning, and liver lobular inflammation based on pathological hepatic steatosis, inflammatory activity, and fibrosis scoring system (SAF), and fibrosis stage≥F2. Binary logistic regression analysis was used to identify the factors influencing high-risk steatohepatitis. A predictive model for diagnosing high-risk steatohepatitis was constructed using R language. The DeLong test was used to compare the area under the curve between groups. Measurement data was compared between groups using the t-test or rank-sum test, and count data were compared between groups using the χ2 test. Results: There were 46 cases (23.7%) with high-risk steatohepatitis. The quantitative ultrasound parameters included elastic modulus (OR=2.958, 95%CI: 1.889-4.883, P<0.001), dispersion coefficient (OR=1.786, 95%CI: 1.424-2.292, P<0.001) and attenuation coefficient (OR=42.642, 95%CI: 3.463-640.451, P=0.004). Serological indexes of fasting blood glucose (OR=1.196, 95%CI: 1.048-1.392, P=0.011), alanine aminotransferase (OR=1.012, 95%CI: 1.006-1.019, P<0.001), aspartate aminotransferase (OR=1.027, 95%CI: 1.014-1.042, P<0.001), γ-glutamyl transferase (OR=1.008, 95%CI: 1.001-1.017, P=0.041) and HDL cholesterol (OR=0.087, 95%CI: 0.016-0.404, P=0.003) were the factors influencing its progression. The AUCs of elastic modulus, dispersion coefficient, attenuation coefficient, multiparametric ultrasound model, serological index model, and ultrasound combined with serology model for the diagnosis of high-risk steatohepatitis were 0.764, 0.758, 0.634, 0.786, 0.773 and 0.825, respectively. The results of the DeLong test showed that the ultrasound combined with the serological model was significantly better than the serological index model and the elastic modulus, dispersion coefficient, and attenuation coefficient alone (P=0.024, 0.027, 0.038 and <0.001). Conclusion: The combination of multiparametric quantitative ultrasound is helpful for the non-invasive diagnosis of high-risk steatohepatitis and possesses great clinical significance.