Properties Of Solutions Research Articles

Microscopic growth of pyridinium oxime based amphipathic on graphite: Effect of relative position of substituents

AbstractAmphipathic molecules with surfactant like properties have several applications ranging from healthcare to the chemical industry. Their ability to form thin films on surfaces with ordered and controllable patterns determines their applicability. Here, we report two pyridinium oxime‐based surfactants, which possess similar aggregation properties in solution, but exhibit substantially different assembly on highly oriented pyrolytic graphite (HOPG) surface. The two compounds are regioisomers with the oxime unit placed either in meta or para position of the pyridinium ring. While the para isomer assembled to anisotropic one‐dimensional (1D) islands and long rod‐like structures, the meta isomer formed two‐dimensional (2D) islands on the HOPG surface. This difference is rationalized through molecular level force‐field calculations that show anisotropy in the growth of the para isomer resulting from an effective overlap of the alkyl chains and oxime groups, which is distinctly not feasible in the assembly of the meta isomer. The assembly of these compounds is compared with another oxime‐containing compound of similar structure, but without the charged pyridinium unit. The charged unit seems to be crucial for the preferential formation of multilayer islands even at low coverage.

Physico-chemical studies and development of water-based drilling fluid formulations with carbon nanotube additives

The paper offers a comprehensive experimental study on the effect of carbon nanotube additives on the features of water-based drilling fluids. A similar study for this fluid has not been carried out before. Nanotubes were used to modify the drilling fluids. Weight concentration of nanomaterials in slurries was from 0.1 to 0.5 %. The formulation of stable drilling slurries modified by carbon nanotube were developed and refined. The study is focused on investigation of rheology, filtration and antifriction properties, temperature and colloidal stability of drilling fluids modified with carbon nanotubes. It is shown that carbon nanotube additives even in small concentrations can significantly change the features of water-based drilling fluids. A comparison was made between the effects of single- and multi-walled carbon nanotubes (SWCNT and MWCNT) on the characteristics of water-based drilling fluids. The study has shown that both types of nano-additives considerably change in the properties of the base fluid. Nevertheless, it was determined that in order to achieve a comparable effect on solution properties, an order of magnitude greater amount of MWCNT additives is required in comparison to single-walled carbon nanotubes.

Mechanochromism of π-conjugated borate derivatives and the effect of intermolecular non-covalent forces on molecular packing and mechanochromic property

We prepared three π-conjugated pinacol borate derivatives anthryl dioxaborolane (ANB), pyrenyl dioxaborolane (PYB) and perylenyl dioxaborolane (PEB) based on anthracene, pyrene and perylene moieties, and studied their optical properties in solid and solution. Interestingly, the three molecules were structurally similar, yet exhibited different optical properties and mechanochromic behavior. Crystal structure studies showed that the mechanical fluorescent response of ANB, PYB and PEB were closely related to the molecular packing modes. Although there were multiple π-π and σ-π interactions in all three molecules, the conjugation degree of ANB was relatively low, resulting in a weak π-π interaction. Therefore, the effective partial parallel packing between adjacent ANB could not form in the initial state, and external mechanical stimulation could not induce the change of optical properties. In PYB and PEB molecules with a high conjugation degree, the π-π interaction was stronger. A partial parallel packing state was formed between the molecules under the synergistic action of π-π and σ-π interaction. Under external disturbance, the relative slippage between molecules was easy to occur. Thus, the characteristic static excimer fluorescence was displayed due to the enhancement of parallel packing. Since the intermolecular interactions of PYB and PEB were a kind of weak non-covalent forces, the packing state changed by external force could return to the initial state at room temperature, showing reversible mechanochromic characteristic. This kind of room temperature reversible force sensitive material constructed by weak non-covalent interactions was expected to be applied and popularized in the fields of encrypted communication and anti-counterfeiting display.

Influence of Iron and Magnesium on Fouling Properties of Organic Matter Solution in Membrane Process.

Organic matter has been identified as a significant type of foulant in membrane processes for water treatment. Its fouling tendency is highly affected by the presence of ions and inorganics. While the effects of ions addition on organic fouling have been extensively researched in the past, studies on the effect of positively-charged inorganics, such as Fe2+ and Mg2+, on organic fouling are limited. This study investigates the influence of Fe2+ and Mg2+ addition on fouling properties of the Suwannee River Organic Matter (SROM) solution in the MF process, with and without Ca2+ ions. Results showed that increasing the concentration of Fe2+ and Mg2+ from 0-5 mM promoted SROM fouling, and resulted in an increased flux decline up to 33% and 58%, respectively. Cake layer resistance became more dominant with the addition of Fe2+ and Mg2+, and was counted for more than 60% of the fouling. Mg2+, however, caused higher internal pore blocking, and facilitated the formation of a less permeable cake layer, compared to Fe2+. This was evident in the analysis of the cake layer properties and the visualization of the fouling layer. In all cases, SROM fouling with Fe2+ and Mg2+ worsened with the addition of Ca2+ ions. The results of the study indicated the importance of understanding the interaction between organic matter and Fe2+ and Mg2+, which would provide useful insights on their fouling mechanism and control.

Electrospun Ibuprofen-Loaded Blend PCL/PEO Fibers for Topical Drug Delivery Applications.

Electrospun drug-eluting fibers have demonstrated potentials in topical drug delivery applications, where drug releases can be modulated by polymer fiber compositions. In this study, blend fibers of polycaprolactone (PCL) and polyethylene oxide (PEO) at various compositions were electrospun from 10 wt% of polymer solutions to encapsulate a model drug of ibuprofen (IBP). The results showed that the average polymer solution viscosities determined the electrospinning parameters and the resulting average fiber diameters. Increasing PEO contents in the blend PCL/PEO fibers decreased the average elastic moduli, the average tensile strength, and the average fracture strains, where IBP exhibited a plasticizing effect in the blend PCL/PEO fibers. Increasing PEO contents in the blend PCL/PEO fibers promoted the surface wettability of the fibers. The in vitro release of IBP suggested a transition from a gradual release to a fast release when increasing PEO contents in the blend PCL/PEO fibers up to 120 min. The in vitro viability of blend PCL/PEO fibers using MTT assays showed that the fibers were compatible with MEF-3T3 fibroblasts. In conclusion, our results explained the scientific correlations between the solution properties and the physicomechanical properties of electrospun fibers. These blend PCL/PEO fibers, having the ability to modulate IBP release, are suitable for topical drug delivery applications.

An exact algorithm for simultaneous pickup and delivery problem with split demand and time windows

This study introduces a new variant of the vehicle routing problem (VRP) called the simultaneous pickup and delivery problem with split demand and time windows (SPDP-SDTW). The motivation behind this study stems from real-life urban and rural delivery scenarios, encompassing features such as split demand, simultaneous pickup and delivery, many-to-many pickup and delivery, and time windows. The study thoroughly investigates the properties of the optimal solution for the SPDP-SDTW. Based on these properties, an arc flow model is developed for the SPDP-SDTW. Dantzig Wolfe (DW) decomposition techniques are employed to obtain the master problem and the pricing subproblem. In order to effectively address the SPDP-SDTW, an improved branch and price (I-BP) algorithm is proposed, incorporating a tailored column generation (CG) algorithm, branching strategies, and dual stabilization strategies. The proposed CG algorithm provides a framework that combines the improved adaptive degree heuristic (I-AGH) algorithm and the solver Gurobi. This integration substantially mitigates the computational burden involved in solving the subproblem. Extensive computational experiments conducted on datasets of varying sizes, including small, medium, and large instances, consistently demonstrate that the I-BP algorithm performs the best in both solution quality and computational efficiency when compared to existing exact and heuristic algorithms.

Analysis of Nonlinear Schrödinger Equations with Time-Dependent Coefficients: Stability and Decay Properties

This study investigates the stability and decay properties of solutions to nonlinear Schrödinger equations (NLSEs) with time-dependent coefficients. Employing a blend of analytical and numerical methods, we delve into how temporal variations in coefficients influence the dynamics of wave functions. Our analysis reveals that time-dependent coefficients significantly affect the stability and decay rates of solutions, uncovering conditions that lead to either enhanced stability or accelerated decay. The findings highlight the critical role of coefficient temporality in dictating the behavior of NLSE solutions. These insights not only advance our theoretical understanding of NLSEs but also bear implications for practical applications in fields modeled by these equations. Our research opens avenues for exploiting time-dependent behaviors in designing systems with desired dynamical properties.

Noncoercive convex sweeping processes with velocity constraints

In this paper, we investigate noncoercive monotone convex sweeping processes with velocity constraints, a topic not previously investigated. Using some fundamental results on Bochner integration, the Tikhonov regularization method, a solution existence result for coercive convex sweeping processes with velocity constraints and a useful fact on measurable single-valued mappings, we prove the solution existence and properties of the solution set of noncoercive convex sweeping processes with velocity constraints under suitable conditions. These results represent a significant contribution, addressing a specific aspect of an open question posed in our recent work [Adly et al., Convex and nonconvex sweeping processes with velocity constraints: well-posedness and insights. Appl Math Optim. 2023;88(Paper No. 45)]. Additionally, we resolve two other open questions from the same paper concerning the behaviour of the regularized trajectories, relying on the Dominated Convergence Theorem for Bochner integration.

A study on the emulsification ability and oil displacement efficiency of polymeric surfactant in porous media

In order to comprehensively comprehend the distinctions in solution properties, emulsification characteristics, and oil displacement efficiency between polymeric surfactant(DG-1) and traditional polymers or surfactants, a comparative analysis was initially conducted on the microstructure, main functional group types, and macroscopic properties. Subsequently, core displacement experiments were employed to elucidate the emulsification capability, emulsion stability, and oil displacement properties of polymeric surfactants. The microscopic displacement experiment was ultimately conducted to investigate the residual oil displacement process in the core following polymer displacement by DG-1, thereby elucidating the underlying mechanisms of microscopic oil displacement by DG-1. The results indicate DG-1 has a molecular structure with a regional network aggregation state as a whole, and a multi-layer aggregation and overlapping structure in space. DG-1exhibits higher viscosity and lower interfacial tension due to the larger molecular coil dimension compared to the equivalent concentration of polymers. The emulsification ability of DG-1 is robust, with emulsion stability positively correlated to oil-polymer ratio and concentration while negatively correlated to migration distance. Core displacement experiments results indicate the polymer-surfactant system (SP) and DG-1 exhibited comparable oil displacement effects, with oil recovery of 54.5 % and 52.4 %, respectively, both surpassing the recovery achieved by the polymer alone (46.9 %). In heterogeneous reservoirs, SP acts as the dominant displacer in regions with moderate and high permeability, whereas DG-1 assumes dominance in regions with moderate and low permeability. The microscopic displacement experiments revealed that DG-1 activated the clustered residual oil as the predominant type of residual oil in porous media, followed by columnar and block residual oil, with film residual oil exhibiting the least activation. Primary mechanisms for oil displacement include extended sweeping volume, shear and carrying effects on the residual oil, and eddy displacement of the residual oil by the emulsion.

The localized excitation on the Jacobi elliptic function periodic background for the Gross–Pitaevskii equation

In this paper, the nonlinear wave solutions for Gross–Pitaevskii equation on the periodic wave background are investigated by Darboux-Bäcklund transformation, from which the soliton and breather wave solutions on the Jacobi elliptic cn and dn functions backgrounds are derived. The corresponding evolutions and dynamical properties of nonlinear wave solutions under different parameters are discussed. These results reported in this paper may raise the possibility of related experiments and potential applications in nonlinear science fields, such as nonlinear optics, oceanography and so on.

Capacitated Mobile Facility Location Problem with Mobile Demand: Efficient Relief Aid Provision to En Route Refugees

As a humanity crisis, the tragedy of forced displacement entails relief aid distribution efforts among en route refugees to alleviate their migration hardships. This study aims to assist humanitarian organizations in cost-efficiently optimizing the logistics of capacitated mobile facilities utilized to deliver relief aid to transiting refugees in a multi-period setting. The problem is referred to as the Capacitated Mobile Facility Location Problem with Mobile Demands (CMFLP-MD). In CMFLP-MD, refugee groups follow specific paths, and meanwhile, they receive relief aid at least once every fixed number of consecutive periods, maintaining continuity of service. To this end, the overall costs associated with capacitated mobile facilities, including fixed, service provision, and relocation costs, are minimized. We formulate a mixed integer linear programming (MILP) model and propose two solution methods to solve this complex problem: an accelerated Benders decomposition approach as an exact solution method and a matheuristic algorithm that relies on an enhanced fix-and-optimize agenda. We evaluate our methodologies by designing realistic instances based on the Honduras migration crisis that commenced in 2018. Our numerical results reveal that the accelerated Benders decomposition excels MILP with a 46% run time improvement on average while acquiring solutions at least as good as the MILP across all instances. Moreover, our matheuristic acquires high-quality solutions with a 2.4% average gap compared to best-incumbents rapidly. An in-depth exploration of the solution properties underscores the robustness of our relief distribution plans under varying migration circumstances. Across several metrics, our sensitivity analyses also highlight the managerial advantages of implementing CMFLP-MD solutions.

Dielectric properties of honey-water solutions over broad frequency range

The dielectric constant (ε′) and dielectric loss (ε″) of pure honey (PH) and honey-water mixtures have been measured over 20 Hz − 20 GHz frequency range, at 26 °C using a precision LCR meter and a Vector Network Analyzer. It has been observed that as water proportion in honey increases, ε′ and ε″ increases over the given frequency range. The dielectric relaxation peak of ε″ for honey-water mixture in the microwave frequency range shifts towards relaxation peak of water as amount of water in honey increases. The normalized ε′/ε′PH ratio is found to increase with increase in water content in Honey, reaching up to 1000 over 20 Hz to 2 kHz. In frequency range from 500 MHz to 5 GHz, ε′/ε′PH ratio approaches a value of 10 times at 750 mg/g. Over 20 Hz to 2 MHz frequency range, ε″/ε″PH ratio approaches 100 times that of PH, but over frequency range from 200 MHz to 600 MHz the ratio ε″/ε″PH is found to decrease anomalously with increase in water content in PH. Further, over the frequency range from 8.2 GHz to 20 GHz the ε″/ε″PH ratio continuously increases with increase in water content.

Development of Hybrid Electrospun Nanofibers: Improving Effects of Cellulose Nanofibers (CNFs) on Electrospinnability of Gelatin.

Cellulose nanofibers (CNFs) were used to improve the electrospinnability of the gelatin protein in a water/ethanol/acetic acid (3:2:3, v/v) solution. The effects of different concentrations of CNFs (0.5-4%) on the important physical properties of the gelatin solution (15%), including rheology, conductivity, and surface tension, were investigated. The apparent viscosity and shear-thinning behavior were increased by increasing the CNF concentration from 0 to 4% at a low shear rate (<10 s-1). CNFs also increased the electrical conductivity and surface tension of the gelatin solution. Scanning electron microscopy (SEM) images revealed uniformly ordered structures with good continuity without fracture or bead formation in all hybrid nanofibers. They also showed that the average diameters of fibers decreased from 216 nm in the pure gelatin nanofibers to 175.39 nm in the hybrid gelatin/CNF (4%) ones. Differential scanning calorimetry (DSC) results showed that CNFs increased Tg, and X-ray diffraction (XRD) analysis showed that the electrospinning process caused the formation of more amorphous structures in the gelatin/CNF hybrid nanofibers. The tensile test indicated that by adding 2% CNFs, the ultimate tensile strength (UTS) and strain at break (SB) of nanofiber mats increased from 4.26 to 10.5 MPa and 3.3% to 6.25%, respectively. The current study indicated that incorporating CNFs at the optimal concentration into a gelatin solution can improve the resulting hybrid nanofibers' morphology, average diameter, and mechanical properties.

Designing Dual-State and Aggregation-Induced Emissive Luminogens from Lignocellulosic Biosourced Molecules.

Utilizing lignocellulosic biosourced platforms, we synthesized novel cyanostilbene (CS) derivatives featuring the 3,4-dimethoxyphenyl moiety. These derivatives were investigated for their emission properties in both solution and solid states. The two simple CS derivatives exhibit very weak luminescence in solution but significant luminescence in the solid state, indicating distinct Aggregation-Induced Emission (AIE) characteristic. Furthermore, combining these two CS units, without conjugation and with quasi perpendicular orientation, results in a Dual-State Emission (DSE) fluorophore showing luminescence both in solution and solid states. X-ray crystallography studies on the solid-state compounds reveal a structure-emission relationship, demonstrating that the colour emission correlates with the conformations adopted by the molecules in the solid state, which influence the type of stacking.

Density and speed of sound measurements of aqueous solutions of potassium formate, potassium bicarbonate and their mixtures

Potassium formate and potassium bicarbonate are currently subject of research in a variety of new potential technical applications. One example of this is the use of the mixture of both salts in solution as a reversible hydrogen storage system and thus as a potential renewable energy carrier. In order to develop these new technologies, knowledge of the thermophysical properties of the individual salt solutions and mixtures is essential. Due to the limited data available in literature, which are only available for the single salt solutions, measurements of density and speed of sound as well as mathematical correlations based on the data were carried out in order to predict the behaviour of the salt solutions as a function of concentration and temperature. Good approximation equations were found for both properties, which agree with the existing data in the literature and result in deviations well below 1 % over wide concentration and temperature ranges. The large number of measurements, the clear trends in the results and the good agreement with existing data from the literature allow to assume that reliable predictions of concentration, and thus degree of hydrogen charging, can be realized utilizing density measurements. With the help of this fundamental research, it will not only be possible to investigate the newly discussed applications in more detail in the future, but also enable more precise design calculations, models and simulations. In addition, material properties that result from the measured variables or are related to them, such as thermal expansion or isentropic compressibility, can be analysed.

RESEARCH OF CROSS-LINKED POLYMER SYSTEMS FOR APPLICATION IN FIELDS CONDITIONS LLC RN-PURNEFTEGAZ

At present time, many oil fields, especially in historically developed areas of oil production, such as Western Siberia, characterized by a mature stage of development, accompanied by a high level of watercut of the produced wells while maintaining significant residual oil reserves. In such conditions, it is necessary to provide for the use of various methods aimed at additional recovery of oil reserves. In particular, it is necessary to provide for the use of tertiary impact methods, a significant share of which is occupied by flow- diverting technologies. The meaning of their application lies in the injection of a small amount of chemical reagents aimed at reducing the permeability of water-washed zones by installing a water-insulating barrier in them and redirecting water filtration flows to previously non-flooded reservoir zones. It should be noted that, unlike most methods of increasing oil recovery, in the case of the use of flow-diverting technologies, the flooding agent does not change — both before and after pumping the rim of chemical reagents, water is used as a flooding agent.From an analysis of literary sources and experience in the use of various types of flow-diverting technologies, it follows that one of the most frequently used technologies, with high versatility of action, is the technology of cross-linked polymer systems based on polymers of the acrylamide series. In this connection, this work presents the results of cross-linked polymer systems studies for selected promising development objects of LLC RN-Purneftegaz. Formulations containing polymers in the concentration range from 0.18 to 1.0 % with the addition of 0,018–0,01 % chromium acetate cross-linker were investigated. Additionally, compositions with the addition of bentonite clay powder in an amount of 0.5 wt.% were studied. A study was carried out of solubility, compatibility with water, crosslinkability of compositions,viscosity properties of initial solutions and crosslinked systems based on them. The thermal stability of cross-linked polymer systems was studied at temperatures from 44 ℃ to 95 ℃ and different mineralization. Recommendations for the use of flow-diverting technologies have been developed.

Forecast Horizon of Dynamic Lot Sizing Problem with Perishable Inventory and Multiple Chain Stores: Shipping and Stockout Cost

Perishable products are very common, but managing inventory of perishable products can be very challenging for firms, especially in distribution systems, including multiple chain stores. In this environment, we consider a dynamic lot-sizing problem faced by a distribution center that dis-patches a single perishable product to multiple chain stores. Demand cannot be backlogged, but it does not have to be satisfied; unsatisfied demand means stockout (lost sale). The first step is to transform the total profit function into a special total cost function. Our next step is to explore the properties of the optimal solution and use them to formulate a dynamic programming algorithm to solve the problem. Furthermore, we establish forecast and decision horizon results, which help the operation manager to decide the precise forecast horizon in a rolling decision-making process. Based on the model setting and the methods of dynamic programming, we obtained two interesting findings: (1) the maximized profit objective function is equivalent to the minimized cost objective function, and (2) the famous zero inventory property conditionally holds in the inventory management of perishable products. On an extensive test bed, useful insights were obtained on the impact of the lifetime of the product and cost parameters on the total cost and length of the forecast horizon. Thus, the contributions of this study are as follows: (1) we explore two structure policies in an optimal solution to devise efficient algorithms to reduce computational complexity; (2) we provide a sufficient condition for forecasting and decision horizons; and (3) we determine that, for a given fixed cost, the median forecast horizon first increases with the lifetime of the product and stockout cost and then remains invariable when it reaches a certain level.

Algebraic solution and thermodynamic properties for the one- and two-dimensional Dirac oscillator with minimal length uncertainty relations

We study the quantum characteristics of the Dirac oscillator within the framework of Heisenberg's generalized uncertainty principle. This principle leads to the appearance of a minimal length of the order of the Planck length. Hidden symmetries are identified to solve the model algebraically. The presence of the minimal length leads to a quadratic dependence of the energy spectrum on the quantum number n, implying the hard confinement property of the system. Thermodynamic properties are calculated using the canonical partition function. The latter is well determined by the method based on Epstein's zeta function. The results reveal that the minimal length has a significant effect on the thermodynamic properties.

Computational insights into the static, solvent and frequency-dependent nonlinear optical properties of head-to-tail novel non-fullerene compounds for modern electro-optic applications

Addressing the growing demand of novel nonlinear optical (NLO) materials, hyper-rayleigh-scattering (HRS) in solution, static and frequency-dependent NLO properties of novel IsoIDTC-based derivatives (AFS1-AFS9) are computed at laser frequencies of 1064 nm and 532 nm to explore SHG β (−2ω, ω, ω) and EOPE β (−ω, ω, 0) for modern electro-optic applications. Structural, electrical, and NLO features were calculated using DFT, and TDDFT modeling, HRS, and DR measurement. The polar, non-polar solvent, and gas phase NLO properties show the highest linear polarizability of 8.92 × 102 a.u. (AFS8) in water, 9.68 × 102 a.u. (AFS5) in gas, and 9.56 × 102 a.u. (AFS) in benzene. AFS8 push-pulls exhibit the highest first hyper-polarizability (βtot) at 1.05 × 105 a.u. and 1.47 × 105 a.u. in gas and benzene solvent, respectively. The proposed chromophores showed substantial SHG and EOPE values at 532 nm and 1064 nm lasers compared toIDT, hence, allowed the successful synthesis of NLO materials for future cutting-edge optoelectronic applications.

An investigation on structural, thermal, mechanical, and optical properties of solution grown β- p-Amino Benzoic Acid single crystal

An investigation on structural, thermal, mechanical, and optical properties of solution grown β- p-Amino Benzoic Acid single crystal