Properties Of Solutions Research Articles

Feeder bus service design under spatially heterogeneous demand

In rapidly sprawling urban areas and booming intercity express rail networks, efficiently designed feeder bus systems are more essential than ever to transport passengers to and from trunk-line rail terminals. When the feeder service region is sufficiently large, the spatial heterogeneity in demand distribution must be considered. This paper develops continuum approximation models for optimizing a heterogeneous fixed-route feeder network in a rectangular service region next to a rail terminal. Our work enhances previous studies by: (i) optimizing heterogeneous stop spacings along with line spacings and headways; (ii) accounting for passenger boarding and alighting numbers on bus dwell times and patron transfer delays at the rail terminal; and (iii) examining the advantages of asymmetric coordination between trunk and feeder schedules in both service directions. To tackle the increased modeling complexity, we introduce a semi-analytical method that combines analytically derived properties of the optimal solution with an iterative search algorithm. Local transit agencies can readily utilize this approach to design a real fixed-route feeder system.This paper reveals many findings and insights not previously reported. For instance, integrating the heterogeneous stop spacing optimization further reduces the system cost (by 4% under specific operating conditions). The cost savings increase with demand heterogeneity but decrease with the demand rate and service region size. Choosing the layout of feeder lines where buses pick up and drop off passengers along the service region’s shorter side also significantly lowers the system cost (by 6% when the service region’s aspect ratio is 1 to 2). Furthermore, coordinating trunk and feeder schedules in both service directions yields an additional cost saving of up to 20%.

Advanced image analysis for medical diagnostics: a system for segmentation and classification using level set methods and AI algorithms

This work aims to implement and utilize an advanced computer system for image analysis and processing through artificial intelligence. The system will evaluate images from multiple sources. As a result, a comprehensive e-Medicus system will be developed to capture and analyze X-ray data and classify cancer cells. This innovative tool, with its unique features tailored for medical facilities, will assist them in capturing and analyzing X-ray images and CT scan results. The e-Medicus system offers several benefits for medical facilities, including efficient automation of photo analysis, tracking changes in a patient's condition over time, and facilitating the identification of medical changes and data classification. A multimedia presentation of the change process will use the contour set function, allowing for topological changes in solution properties. The system integrates novel procedures and algorithms from theoretical computer science and numerical mathematics, leveraging neural networks, genetic algorithms, semantic networks, image ontology, rough set theory, contour set methods, and hybrid algorithms. These developed algorithms enhance methods and concepts in image segmentation, gathering, transmitting, storing, extracting, and effectively presenting information.

Application and Optimization of Rheological Mathematical Models in Preparation and Injection Process of Polymer Flooding

The impact of shear on the properties of polymer solutions is not fully accounted for in the simulation of conventional rheological models. To optimize the application of these mathematical models, the shear rheological characteristics of polyacrylamide at various concentrations were investigated under different shear rates and shear modes. The results indicate that pseudoplastic fluid polymers exhibit two distinct rheological characteristics within their "shear thinning" rate range. The critical shear rate at this threshold signifies the point at which shear stress begins to disrupt the structure of the polymer solution, resulting in a rheological curve that transitions from high to low shear rates without reverting back to a low-to-high state. The concentration of the solution has minimal effect on the critical shear rate of the polymer, which is primarily determined by the inherent properties of the polymer itself. The application of rheological models during preparation and injection processes can elucidate the effects of shear on polymers by analyzing changes in apparent viscosity. Furthermore, the rheological model following supercritical shear rates requires modifications to the consistency coefficient (K) and flow index (n) based on shear rheological data obtained from high to low shear rates.

Capillary Flow-Based One-Minute Quantification of Amyloid Proteolysis.

Quantifying the formation and decomposition of amyloid is a crucial issue in the development of new drugs and therapies for treating amyloidosis. The current technologies for grasping amyloid formation and decomposition include fluorescence analysis using thioflavin-T, secondary structure analysis using circular dichroism, and image analysis using atomic force microscopy or transmission electron microscopy. These technologies typically require spectroscopic devices or expensive nanoscale imaging equipment and involve lengthy analysis, which limits the rapid screening of amyloid-degrading drugs. In this study, we introduce a technology for rapidly assessing amyloid decomposition using capillary flow-based paper (CFP). Amyloid solutions exhibit gel-like physical properties due to insoluble denatured polymers, resulting in a shorter flow distance on CFP compared to pure water. Experimental conditions were established to consistently control the flow distance based on a hen-egg-white lysozyme amyloid solution. It was confirmed that as amyloid is decomposed by trypsin, the flow distance increases on the CFP. Our method is highly useful for detecting changes in the gel properties of amyloid solutions within a minute, and we anticipate its use in the rapid, large-scale screening of anti-amyloid agents in the future.

An Experimentally Derived Prediction Model for Diffusion and Electrostatically Controlled Physical Interactions of Polyampholytes and Salts

AbstractThe interactions of salts with polyampholytes are well established using the Hofmeister series. However, the effect of these salts on the diffusivities of polyampholytes is unknown. This article discusses these electrostatically driven physical interactions using two developed prediction models. Sodium and Potassium salts are considered with 3 chaotropic anions and 2 kosmotropic anions. A dimensionless parameter has been developed to predict the trend for these salt interactions. Another model has been developed to predict these interactions for different salt mixtures. The effect of these salts and the mixtures on the second virial coefficient is also studied, and statistical clustering using the k‐means method has been defined, which can provide insight towards the changes in the solution properties of polyampholytes with these salt mixtures. At lower pH, the salt first screens the repulsions in the polyampholytes followed by a re‐expansion phenomenon.

Designing delafossite CuAl1-xTMxO2 solid solutions: the role of 3d transition metal spin states in photo(electro)catalytic performance

This study delves into the effects of 3d transition metal (TM) spin states on the structural and electronic properties of CuAl1-xTMxO2 solid solutions, focusing on their implications for photo(electro)catalytic performance. The research reveals that the Jahn–Teller distortion, associated with TM3+, is a critical factor in determining the lattice parameters and photo(electro)catalytic performances. Solid solutions without Jahn–Teller distortion adhere to Vegard's law, whereas those with strong distortion exhibit deviations, indicating the influence of TMO6 octahedral distortion on solubility and lattice parameters. The electronic structure of solid solutions with weak Jahn–Teller distortion is governed by the O–Cu–O and TMO6 crystal fields, which leads to a narrowed bandgap and reduced conduction band minimum (CBM), impacting the hydrogen evolution potential. In particular, the CuAl0.5Cr0.5O2 shows a significant enhancement in photocurrent density and hydrogen production rate due to its balanced light absorption and effective charge carrier separation. In contrast, the weak Jahn–Teller distortion in CuAl1-xFexO2 results in localized electronic states at CBM, leading to diminished carrier mobility. Solid solutions with strong Jahn–Teller distortion, such as CuAl1-xTMxO2 (TM = Mn and Ni), display a range of electronic properties from semiconductor to semimetallic, with the semimetallic CuAl0.9Mn0.1O2 capable of infrared light absorption and efficient photocatalytic hydrogen and oxygen production.

Probing the contribution of bismuth on electronic transport and phonon scattering properties of Mg3Sb2-xBix solid solutions

In this work, first-principles calculations have been used to investigate the electronic structure, phonon scattering, and Debye temperature of Mg3Sb2-xBix alloys. The electronic transport properties were predicted by solving the Boltzmann equations. Additionally, thermoelectric properties of alloys with corresponding compositions prepared using directional solidification were analyzed and compared with the predicted results. The research findings reveal that the increase in Bi content is accompanied by an increase in carrier concentration and mobility, and a decrease in carrier effective mass. The Mg3Sb1.5Bi0.5 alloy showed the highest power factor value of 0.49 mWm−1K−2 due to the synergistic effect between the electrical conductivity and the Seebeck coefficient. As the Bi atoms replace Sb sites, the scattering rates of low-frequency phonons become stronger, significantly reducing the lattice thermal conductivity. The Mg3Sb0.5Bi1.5 alloy reaches the lowest thermal conductivity, especially in the low and medium temperature range. Mg3Sb1.5Bi0.5 alloy provides the maximum ZT value of 0.29 at 630 K. This study systematically analyzes the impact of Bi on electronic transport and phonon scattering in Mg3Sb2-xBix alloys，and extensively discusses the dependence of thermoelectric performance parameters on Bi content. This work also provides a theoretical reference for the subsequent research on doping modification of Mg3Sb2-xBix alloys.

Wave propagation in the Kolmogorov–Petrovskii–Piskunov–Fischer equation with time delay and spatial deviation

For the logistic equation with diffusion two generalizations are considered: one with time delay and the other with deviation in the spatial variable. For these equations, the problem of density wave propagation is considered. These equations, known as Kolmogorov–Petrovsky–Piskunov–Fisher equations with delay or deviation (KPPF with delay or deviation), are investigated using both asymptotic and numerical methods.To investigate the qualitative behavior of solutions of such equations, the wave profile equation is considered and the conditions for the emergence of its oscillatory modes are identified.The local properties of solutions with periodic boundary conditions are examines, revealing that an increase in the period leads to the emergence of stable solutions with a more complex spatial structures.Numerical analysis of the wave propagation process indicates that at sufficiently small delay values, this equation has solutions that are close to those of the standard KPPF equation. Increasing the delay parameter leads first to the appearance of a damped oscillatory component in the spatial distribution of the solution. With further increases of this parameter, a complex spatial profile of the wave appears.In the final part of the chapter, which focuses on numerical calculation, the numerical analysis of the wave propagation process from two initial perturbations is performed. This analysis tracks the process of wave interaction. The complex spatially inhomogeneous structure that arises during wave propagation and interaction can be explained by the properties of the corresponding solutions of the periodic boundary value problem, especially as the interval of change in the spatial variable increases.

Transport Properties of Aqueous Methane Solutions and Blocking Behavior of Intelligent-Responsive Temporary Plugging Agent in a Switchable Nano-channel: A Dissipative Particle Dynamics Simulation Study.

Intelligent-responsive temporary plugging agents (TPAs) have great potential in the field of oil and gas resource extraction due to their self-adaptability to the environment. However, the transport mechanism of oil and gas molecules, such as aqueous methane solution in intelligent-responsive TPA-modified nano-channels and the blocking behavior of TPA, have not been verified yet. In this work, dissipative particle dynamics simulations (DPD) are conducted to investigate the velocity distribution and the force characteristics of aqueous methane solutions under different driving velocities, as well as the blocking effect of TPA to the flow of solution. Simulation results indicate that aqueous methane solution primarily concentrates in theuncovered area of the TPA and diffuses into the TPA-covered area when the nano-channel is closed. The velocity distribution of the flowing solution in the open nano-channel follows a subparabolic pattern. Methane molecules in the closed nano-channel show sharp oscillations in velocity and force profiles, which can be mitigated by increasing the methane concentration. The designed TPA effectively blocks fluid flow but its head and tail are vulnerable to the shear forces from the fluid. This study enhances the understanding of the nanoflows in the wellbores during the extraction of oil and natural gas resources.

Genesis and regulation of C-terminal cyclic imides from protein damage.

C-Terminal cyclic imides are post-translational modifications (PTMs) that can arise from spontaneous intramolecular cleavage of asparagine or glutamine residues resulting in a form of irreversible protein damage. These protein damage events are recognized and removed by the E3 ligase substrate adapter cereblon (CRBN), indicating that these aging-related modifications may require cellular quality control mechanisms to prevent deleterious effects. However, the factors that determine protein or peptide susceptibility to C-terminal cyclic imide formation or their effect on protein stability have not been explored in detail. Here, we characterize the primary and secondary structures of peptides and proteins that promote intrinsic formation of C-terminal cyclic imides in comparison to deamidation, a related form of protein damage. Extrinsic effects from solution properties and stressors on the cellular proteome additionally promote C-terminal cyclic imide formation on proteins like glutathione synthetase (GSS) that are susceptible to aggregation if the protein damage products are not removed by CRBN. This systematic investigation provides insight to the regions of the proteome that are prone to these unexpectedly frequent modifications, the effects of this form of protein damage on protein stability, and the biological role of CRBN.

Engineering Thin Films of Silicon Phthalocyanines for Organic Thin Film Transistors

Metal phthalocyanines (MPc) show great promise as semiconductors due to their exceptional optoelectronic properties, high thermal and photochemical stability, and ability to be easily synthesized and functionalized for specific applications. The metal/metalloid ion in the center of the MPc ring can significantly influence the electronic, optical, and magnetic properties of the compound, as well as its solubility and stability. The majority of MPc, such as copper phthalocyanine (CuPc) are used as hole-transport materials (p-type) in organic electronics. Silicon phthalocyanines (R2-SiPc) are emerging semiconductors which predominantly moves electrons and have led to high performance n-type organic thin-film transistors (OTFTs). Their low synthetic complexity paired with their versatile axial group facilitates the finetuning of their chemical properties, solution properties and processing characteristics without significantly affecting their frontier orbital levels or their absorption properties. The crystal engineering and film forming characteristics of R2-SiPc semiconductors can be tuned through appropriate axial group functionalization, therefore facilitating their integration into both OTFTs and OPVs by solution processing or vapor deposition.Our group has developed families of R2-SiPc and integrated them into OTFTs with an emphasis on thin film processing and engineering of the interfaces for improved device performance. We have established structure property relationships of the final device performance as a function of 1) R2-SiPc axial groups and peripheral groups, 2) surface chemistry and composition and 3) thin film deposition conditions. I will also be discussing our recent work using advanced film characterization such as polarized Raman microscopy and synchrotron based scanning transmission x-ray microscopy to evaluate the resulting films and optimize the OTFT performance. Figure 1

Surface activity, wettability and foam properties of quaternary ammonium surfactants with C-F/Si-H double hydrophobic backbone

This paper reported the synthesis of a novel quaternary surfactant (PFAS-Si) containing the C-F/Si-H double hydrophobic skeleton and the surface properties of its aqueous solution, which were investigated in comparison with those of the aqueous solutions of the fluorosurfactant (PFAS-IEt) and silicone surfactant (TMSAC) with similar hydrophobic chain structures. The critical micelle concentration (CMC) and the corresponding surface tension value (γCMC) of the PFAS-Si solution were 0.0612 mmol/L and 21.02 mN/m, respectively, which indicated that the PFAS-Si could substantially reduce the surface tension of water, and showed excellent surface activity. Meanwhile, the thermodynamic parameters of the micellization process, aggregation behavior, wettability, and foam properties of PFAS-Si solutions were systematically investigated. On the TEM negative staining photographs, it can be clearly seen that the aggregates of PFAS-Si in aqueous solution exhibit hollow spherical vesicles. In addition, the PFAS-Si solution exhibited superb wettability, and could achieve wetting of PTFE sheets at a very low concentration (0.168 mmol/L). Not only that, the PFAS-Si solution also had excellent foaming ability and foam stability. This work provided a new preparation idea for the development of high-performance specialty surfactants.

Influence of pH on the emulsifying property of high methyl-esterified citrus pectin in the presence of calcium cations

High methyl-esterified citrus pectin (HMCP) is often used as a thickness in food products and is considered a poor emulsifier, especially in neutral pH solutions. Our previous findings show that the emulsifying capacity of HMCP could be significantly enhanced by calcium cations. Besides, the pH of the solution decreased in the presence of calcium cations. However, the impact of solution pH on HMCP emulsifying capacity in the presence of calcium cations is unclear. In this study, the pH of the HMCP solution was adjusted from 3.00 to 8.00 before adding calcium cations. The solution properties and emulsifying properties were analyzed in light of the existence of calcium cations. The results showed that the pH of the HMCP solutions decreased after bringing calcium cations into them. Calcium cations could change the solution rheological properties, particle size distributions and morphologies, and the particle microenvironmental hydrophobic areas in HMCP solutions while increasing the pH of HMCP solutions, contributing to improving the emulsifying capacity of HMCP. HMCP had the best emulsifying ability when the pH of the HMCP solutions was kept at a neutral level. This research gives us new ideas to adjust the emulsifying property of HMCP.

Nonlinear Poisson-Boltzmann solutions for charged parallel plates: When opposite charges repel.

I present an exact solution of the Poisson-Boltzmann equation for two parallel plates and discuss the solution properties. I discuss in more detail plates with opposite charges: In this case, there are two critical separations, Lc,1 < Lc,2. For separations less than Lc,1, the force between plates is repulsive. It switches to attractive at Lc,1, but with the electric potential having the same signon both plates. For L > Lc,2, the force remains attractive, and the potential at the plates has the same signas the charge on each plate. I also describe charge regulation, determined by pKa, and provide formulas for both the critical distance where oppositely charged plates repel and their charging process. The implications of these results for the nanoparticle assembly, as driven by electrostatic interactions, are also discussed.

Structure and Physicochemical Properties of Solutions of Lithium Polysulfides in Tetrasolvate of Lithium Perchlorate with Sulfolane Molecular Dynamics Modeling.

Lithium polysulfides are intermediate products formed during the discharge and charge of lithium-sulfur batteries and have good solubility in electrolyte solutions. Therefore, the properties and structure of solutions of lithium polysulfides in electrolyte solutions affect the energy characteristics of the lithium-sulfur battery. In this work, the structure and physicochemical properties (density, ionic conductivity, and self-diffusion coefficients) of solutions of lithium disulfide, tetrasulfide, and octasulfide in lithium perchlorate tetrasolvate with sulfolane in a wide range of concentrations (0.2-12 M) were studied using the molecular dynamics method. With increasing concentrations of lithium polysulfides, the proportion of sulfur atoms in the coordination sphere of the lithium cation increases and the proportion of sulfolane molecules decreases. It has been established that the ability of the polysulfide anion to act as a bridging ligand leads to the formation of clusters, including lithium perchlorate, lithium polysulfides, and sulfolane. It has been shown that the tendency to form clusters increases with an increasing number of sulfur atoms in the polysulfide anion. At high concentrations of lithium polysulfides, regardless of their size, the electrolyte system becomes a single cluster. With an increase in the concentration of lithium polysulfides in the electrolyte system, its density increases and the ionic conductivity and diffusion coefficients of the system components decrease.

Ab-initio investigation of stability and electronic properties of new yttrium-based solid solution of double transition metal YMXTx (M= Ti and zr; X= C and N; Tx= H, O, and F) MXenes

In this study, an extensive examination was carried out to explore the stability, and physical characteristics of a novel solid solution comprising two transition metals, namely YMXTx (M = Ti and Zr; X = C and N; Tx = H, O, and F) MXenes. The Quantum-Espresso computational package which is based on density functional theory (DFT) and pseudopotential techniques has been employed for performing calculations. The results obtained from the investigation of the structural, dynamic, and mechanical stability revealed that the YTiX and YZrX MXenes exhibited remarkable stability. These findings strongly suggest the feasibility and potential success of experimental synthesis of these materials. Furthermore, the result of cohesive energy indicated that Nitride-based MXenes (Y(Ti/Zr)N) are more stable than Carbide-based MXenes (Y(Ti/Zr)C). By performing comprehensive calculations of the total density of states and band structures, using various approximations such as LDA, GGA, and GGA + HSE06, the investigation revealed a metallic behavior in YMX MXenes. Additionally, the analysis of the TDOS revealed the presence of a pseudogap close to the Fermi level. This observation provides further evidence for the structural stability of the investigated mentioned MXenes. After undergoing saturation with different functional groups, it was observed that the YTiNH2 and YTiNF2 MXenes displayed semiconducting behavior, whereas YZrNO2 is classified as a non-conductive material, and the remaining monolayers exhibit metallic properties. Analyses of charge density and electron localization functions confirmed the metallic behavior of the studied MXenes. Modifying the electronic band gap of 2D MXenes, while also preserving structural stability, could lead to enhancing the application of these materials in optoelectronic devices.

Global Existence and Some Qualitative Properties of Weak Solutions for a Class of Heat Equations with a Logarithmic Nonlinearity in Whole $${\mathbb {R}}^{N}$$

Global Existence and Some Qualitative Properties of Weak Solutions for a Class of Heat Equations with a Logarithmic Nonlinearity in Whole $${\mathbb {R}}^{N}$$

Electrical conductivity based algorithm for precise application of liquid nitrogenous fertilizers

Precise application of nitrogenous fertilizers mainly urea ammonium nitrate (UAN) and granular urea (both pure and neem-coated) in aqueous form, is critically important for basal and foliar applications. The physicochemical properties of aqueous solution of these nitrogenous fertilizers plays important role in design of any liquid fertilizer application system. The study was carried out during 2019–20 at ICAR-Indian Agricultural Research Institute, New Delhi with an aim to develop algorithms for use in sensors-based systems for real time monitoring of available N concentration in the fertilizer solution before its application. The physicochemical properties like pH, electrical conductivity (EC), specific gravity (SG), dynamic viscosity (DV), surface tension (ST) and percentage light absorbance (LA) of urea ammonium nitrate (UAN-28%), pure urea, and neem coated urea in diluted form (pre-selected N-concentrations i.e. 0.78, 0.9, 1.08, 1.33, 1.75, 2.54 and 4.67% corresponding to the dilution ratios of 1:35, 1:30, 1:25, 1:20, 1:15, 1:10 and 1:05) were measured and analyzed for their significance with N-concentration. Electrical conductivity (EC) alone showed a significant relationship with N-concentrations. Prediction models were developed for diluted UAN and granular urea fertilizers based on the EC and N-concentrations. The regression models in terms of EC to predict N-concentration had coefficients of determination (R2) of 0.998, 0.998, and 0.999 for diluted UAN, pure urea, and neem coated urea with water, respectively showed a great potential for their sensor based precise application. The controlled application of diluted liquid fertilizers with water can be achieved through sensing relevant physicochemical property.

Longitudinal ultrasound measurements of polyethylene oxide across dilute to concentrated aqueous solutions

Measuring the properties of polymer solutions is crucial for understanding fundamental polymer physics. The longitudinal ultrasound measurement method offers a promising technique for characterizing these properties. In this study, we develop a mathematical model to correlate longitudinal ultrasonic signals with the material properties of polyethylene oxide (PEO) from dilute to concentrated aqueous solutions. After applying reflection and diffraction corrections, the accuracy of the measurement results improves to over 97 %. Our findings reveal a positive correlation between the speed of sound, density, and longitudinal modulus with the mass concentration of PEO. Additionally, ultrasonic relaxation analysis reveals that PEO solutions exhibit at least one relaxation process in the frequency range of 3–7 MHz, independent of concentration and molecular weight. Compared to dilute solutions, the relaxation amplitude in concentrated solutions is larger and accompanied by strong nonlinearity, attributed to conformational changes caused by molecular entanglement in concentrated solutions.

Micro-PIV of viscoelastic fluid flow in microporous media

The present experimental investigation combines the bulk flow properties of polymer solutions and measurable rheological parameters as they flow through a distinctive micro-porous structure, with micro-PIV (micro-particle image velocimetry) to measure the velocity distribution and velocity fluctuations within individual pores of a novel porous glass structure. To investigate the effects of fluid elasticity at pore scale, aqueous solutions of a polyacrylamide (PAA) & polyethylene oxide (PEO) in the concentration range of 50–200 ppm, which were characterized in both shear and extensional flows using shear and capillary break-up extensional rheometers (CaBER) respectively, were used as working fluids. The velocity field measurement includes the velocity magnitude and fluctuation intensity in several different pores within the porous material across a Weissenberg number Wi range of approximately 0.01 to 1 for each of the test fluids. The global averaged fluctuation intensity increases with Wi but the critical value, which indicates the onset of significant unsteadiness (i.e. well above noise floor/Newtonian baseline) within the flow at pore scale gives an approximately constant value of Wi≈0.4, which is almost 40 times higher than the value that is observed in the pressure-drop measurements for the data to rise above the Newtonian base line. We therefore postulate that the enhanced pressure-drop behaviour of the bulk flow may not be due to local velocity fluctuations within the pores but due to mean flow effects, at least over a significant portion of the data (up to Wi≈0.4).