Dispersion Forces Research Articles

Interaction mechanism of triclosan on pristine microplastics

Urban wastewaters comprise different hydrophobic pollutants such as microplastics (MPs), pharmaceuticals, and personal care products. Among these pollutants, triclosan (TCS) shows a worrying interaction ability with MPs; recent studies show MPs serve as a vector between TCS and aquatic environments, whose interaction is still being studied to understand their combined toxicity and transport ability. Using computational chemistry tools, this work evaluates the TCS-MPs interaction mechanism, including pristine polymers, i.e., aliphatic polyamides (PA), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). Our results show that TCS adsorption on MPs solely occurs via physisorption, where PA reaches the higher adsorption ability. Remarkably, MPs reach higher or comparable adsorption stability than carbon-based materials, boron nitrides, and minerals, indicating their worrying transport properties. Also, the adsorption capacity is strongly influenced by entropy changes rather than thermal effects, which determine the different sorption capacities among polymers and agree well with reported sorption capacities from adsorption kinetic experiments in the literature. MPs show a polar and highly susceptible surface to establish electrostatics and dispersion effects on TCS. Accordingly, the TCS-MPs interaction mechanism arises from the interplay between electrostatics and dispersion forces, with a combined contribution of 81–93 %. Specifically, PA and PET maximize the electrostatic effects, while PE, PP, PVC, and PS maximize the dispersion effects. From the chemical viewpoint, TCS-MPs complexes interact by a series of pairwise interactions such as Van der Waals, hydrogen bonding, C-H⋯π, C-H⋯C-H, C-Cl⋯C-H, and C-Cl⋯Cl-C. Finally, the mechanistic information explains the effects of temperature, pressure, aging, pH, and salinity on TCS adsorption. This study quantitatively elucidates the interaction mechanism of TCS-MP systems, which were hard to quantify to date, and explains the TCS-MPs sorption performance for sorption/kinetic studies.

Many-body dispersion in model systems and the sensitivity of self-consistent screening.

London dispersion is a weak, attractive, intermolecular force that occurs due to interactions between instantaneous dipole moments. While individual dispersion contributions are small, they are the dominating attractive force between nonpolar species and determine many properties of interest. Standard semi-local and hybrid methods in density-functional theory do not account for dispersion contributions, so a correction such as the exchange-hole dipole moment (XDM) or many-body dispersion (MBD) models must be added. Recent literature has discussed the importance of many-body effects on dispersion, and attention has turned to which methods accurately capture them. By studying systems of interacting quantum harmonic oscillators from first principles, we directly compare computed dispersion coefficients and energies from XDM and MBD and also study the influence of changing oscillator frequency. Additionally, the 3-body energy contributions for both XDM, via the Axilrod-Teller-Muto term, and MBD, via a random-phase approximation formalism, are calculated and compared. Connections are made to interactions between noble gas atoms as well as to the methane and benzene dimers and to two layered materials, graphite and MoS2. While XDM and MBD give similar results for large separations, some variants of MBD are found to be susceptible to a polarization catastrophe at short range, and the MBD energy calculation is seen to fail in some chemical systems. Additionally, the self-consistent screening formalism used in MBD is shown to be surprisingly sensitive to the choice of input polarizabilities.

Lattice-water tweaked Cis-Trans isomerism of a copper(II)-dipyridylamine-azide complex and their aggregation features

This work highlights an interesting study on lattice-water mediated cis-trans isomerism of hydrated mononuclear copper(II) complexes, [Cu(dpa)2(N3)2].xH2O (x = 1,2) containing bidentate chelatant 2,2′-dipyridyl amine (dpa) and co-ligand, azide ion (N3−) and their aggregation characteristics. A variation in the water–methanol (v/v) solvent mixture leads to a successful synthesis of the geometric isomers of the mononuclear hydrated copper(II) complexes. X-ray crystallography evaluates the crucial role of lattice water along with various non-classical forces for the isomeric existence of the copper complexes. Thermal gravimetric analysis, Hirshfeld surface and energy framework analysis attribute the significant contribution of dispersive forces in the formation and preferential isolation of the geometric isomers. Further, the aggregation properties of the geometric isomers have been assessed with spectroscopic characterization attributing an interesting change in the photophysical, structural and morphological features of the molecular aggregates. The facets of the structural and physicochemical properties of the geometrical conformers and their molecular aggregates have also been unveiled.

The Combustion Characteristics of Calophyllum inophyllum Fuel in the Presence of Magnetic Field

The study objective is to investigate the combustion characteristics of Callophyllum inophyllum fuel in presence of a magnetic fields. To conduct the experiment, a bunsen burner was utilized, with fuel and air being dispensed via a syringe pump and compressor, both regulated by a flowmeter. The fuel and air pipes were heated to 532.15 (K) to facilitate fuel evaporation. The equivalent ratio of 0.5, 1, and 1.5 was adjusted to control air discharge and fuel. An 11,000 gausses artificial magnet was used, with N-S, N-S, N-N, and S-S being the various magnetic pole configurations. The study found that the magnetic field can enhance combustion quality by affecting the molecules involved in the combustion process. The magnetic field's force also intensifies the movement of O2, making it more energetic. As O2 travels from the North Pole to the South Pole through the combustion reaction zone, it quickens the oxidation-reduction process and curtails diffusion combustion. The red color's intensity diminishes with the magnetic field's effect, indicating this phenomenon. When a magnetic field is applied, the polarity of C.inophyllum biodiesel fuel becomes highly favorable. The triglyceride carbon chain bonds become unstable, and the van der Walls dispersion forces are weakened, which facilitates easier O2 binding to the fuel, resulting in more efficient combustion. An increase in the laminar burning velocity value can be noticed when exposed to a magnetic field.

Understanding and Describing London Dispersion Effects in ­Transition-Metal-Catalyzed C–H Activations

AbstractTransition-metal-catalyzed C–H activation has emerged as a powerful strategy for molecular synthesis with unique levels of resource economy. Weak secondary dispersion interactions were found to play an essential role in these transformations in terms of kinetic efficacy and selectivity. This Account summarizes our group’s recent progress in the rationalization and quantification of London dispersion effects within the transition-metal-catalyzed C–H activation.1 Introduction2 Annulation Reactions3 Alkylation Reactions4 Arylation Reactions5 Olefination Reactions6 Oxygenation Reactions7 Conclusion

Preparation, stability, and molecular modeling of nitro-oleic acid/cyclodextrin complexes under aqueous conditions

Nitro-oleic acid (NO2-OA) is an endogenously produced pleiotropic modulator involved in cell redox homeostasis. The intrinsic property of NO2-OA is a decay reaction under aqueous conditions. This aqueous instability is simultaneously a problematic issue for NO2-OA sample handling and NO2-OA application in general. In this work NO2-OA (eq. mol. 9/10-NO2 isomers) was encapsulated with β-cyclodextrin (β-CD). The formation of the β-CD/NO2-OA complex was determined based on 1H NMR. The QM calculations revealed that dispersion forces are crucial for the stability of the complex. Based on thermogravimetry–differential scanning calorimetry, free NO2-OA was less thermally stable than its inclusion β-CD complex. The electrochemical reduction of the nitro group was investigated to determine the degradation kinetics of β-CD/NO2-OA. Under aqueous conditions, β-CD/NO2-OA degrades at a similar rate to NO2-OA alone. However, when β-CD/NO2-OA is stored in solid (lyophilized) form, no degradation was observed for a one-month period.

A supramolecular self-assembly of peptide-derived compounds via 1,5-disubstituted tetrazole-based supramolecular synthons: An experimental and computational study

The tetrazole moiety is a versatile scaffold in medicinal chemistry due to its specific structure and essential roles in biosciences. Here, a supramolecular behavior of newly synthesized benzyl 2-[5-(benzyloxycarbonylaminomethyl)tetrazol-1-yl)-3-phenyl-propanoate, 1, was studied by single-crystal X-ray crystallography and computational techniques, and compared with 21 structurally diversified 1,5-disubsituted tetrazole-containing peptide-derived structures, retrieved from the Cambridge Structure Database, providing a library of tetrazole-based H-bonding synthons reported for the first time. Hirshfeld surface analysis, followed by the enrichment ratios, demonstrates that the supramolecular assembly of this class of compounds was controlled mainly by O…H, N…H, C…H and π-stacking interactions. Synergy of π…π and X-Y…π (X=C, N; Y=H, F) inter-contacts leads to diverse supramolecular patterns. The 3D topologies of the supramolecular architectures were visualised via energy frameworks, revealing a high contribution of dispersion forces. Using a quantum-chemical treatment, the molecular electrostatic potential and the HOMO and LUMO levels designated the chemical activity and stability of the compound. The compilation of these findings provides valuable information that may eventually form the basis of the design of more effective therapeutic agents containing tetrazole motifs.

High-Order Quantum-Mechanical Analysis of Hydrogen Bonding in Hachimoji and Natural DNA Base Pairs.

High-order quantum chemistry is applied to hydrogen-bonded natural DNA nucleobase pairs [adenine:thymine (A:T) and guanine:cytosine (G:C)] and non-natural Hachimoji nucleobase pairs [isoguanine:1-methylcytosine (B:S) and 2-aminoimidazo[1,2a][1,3,5]triazin-4(1H)-one:6-amino-5-nitropyridin-2-one (P:Z)] to see how the intermolecular interaction energies and their energetic components (electrostatics, exchange-repulsion, induction/polarization, and London dispersion interactions) vary among the base pairs. We examined the Hoogsteen (HG) geometries in addition to the traditional Watson-Crick (WC) geometries. Coupled-cluster theory through perturbative triples [CCSD(T)] extrapolated to the complete basis set (CBS) limit and high-order symmetry-adapted perturbation theory (SAPT) at the SAPT2+(3)(CCD)δMP2/aug-cc-pVTZ level are used to estimate highly accurate noncovalent interaction energies. Electrostatic interactions are the most attractive component of the interaction energies, but the sum of induction/polarization and London dispersion is nearly as large, for all base pairs and geometries considered. Interestingly, the non-natural Hachimoji base pairs interact more strongly than the corresponding natural base pairs, by -21.8 (B:S) and -0.3 (P:Z) kcal mol-1 in the WC geometries, according to CCSD(T)/CBS. This is consistent with the H-bond distances being generally shorter in the non-natural base pairs. The natural base pairs are energetically more stabilized in their Hoogsteen geometries than in their WC geometries. The Hoogsteen geometry makes the A:T base pair slightly more stable, by -0.8 kcal mol-1, and it greatly stabilizes the G:C+ base pair, by -15.3 kcal mol-1. The G:C+ stabilization is mainly due to the fact that C has typically added a proton when found in Hoogsteen geometries. By contrast, Hoogsteen geometries are substantially less favorable than WC geometries for non-natural Hachimoji base pairs, by 17.3 (B:S) and 13.8 (P:Z) kcal mol-1.

How Accurately Can DFT Describe Non-valence Anions?

Weakly bound non-valence anions are molecular systems where the excess electron stabilizes in a very diffuse orbital whose size, shape, and binding energy (∼1-100 meV) are governed by the long-range electrostatic potential of the molecule. Its binding energy comes mainly from charge-dipole or charge-multipole interactions or dispersion forces. While highly correlated methods, like coupled cluster methods, are considered to be the state of the art for describing anionic systems, especially when the electron lies in a very diffuse orbital, we consider here the possibility to use DFT-based calculations. In such molecular anions, the outer electron experiences long-range exchange and correlation interactions. We show that DFT can describe long-range bound states provided that a correct asymptotic exchange and correlation potential is used, namely, that from a range-separated hybrid functional. This opens an alternative to the computationally demanding highly correlated method calculations. It is also suggested that the study of weakly bound anions could help in the construction of new DFT potentials to study systems where nonlocal effects are significant.

Investigation of Asphaltene Polydispersity, Stability, and Deposition on Steel Using XDLVO Theory

The characterization and analysis of asphaltene particles are very crucial in the petroleum industry as the precipitation and subsequent deposition of asphaltenes cause formation damage and clogging of wellbore and production equipment, leading to production decline and operational drawbacks. In this study, the polydispersity of asphaltenes and the interaction between asphaltenes were probed by using the surface energy concept. Asphaltenes from three different oil fields in the Gulf of Mexico (GOM) were selected for this study. The results revealed that asphaltenes destabilized by different precipitants in the lab or from different assets in the field have distinctive surface energy values. Dispersive force was the dominant force of asphaltenes in oil systems. However, increasing polar forces appeared to increase the attractive interaction between asphaltenes which can in turn lead to higher aggregation and precipitation tendency. The magnitude of polar force is proportional to the content of heteroatoms and has a higher value for asphaltenes that were destabilized and then deposited by smaller alkanes. The stability of asphaltenes in oil from various fields and their deposition on steel were also investigated using the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. The results showed that van der Waals and acid–base interactions, among other components of the surface energy, were dominant in promoting asphaltene aggregation and deposition by increasing the attractive force between similar asphaltenes and asphaltene-steel, respectively. These findings were further supported by the concept of works of cohesion and adhesion. The results showed that asphaltenes were unstable and had the tendency to deposit on the steel substrate. The total interaction energy between asphaltene and steel, obtained from the XDLVO theory, and the work of adhesion correlated well with the amounts of asphaltene deposition generated by experimental lab setups. Interfacial tension between asphaltene and steel can provide information about the bond stability and deposit persistence under shear.

Stability and electronic properties of aromatic and heteroaromatic molecules for Guest@MOF complexes

A set of Guest@Host complexes formed by aromatic and heteroaromatic guest molecules encapsulated into the [Zn2(SDC)2(An2Py)] as host structure was computationally investigated. The stability of these complexes was characterized by energy decomposition and intermolecular interaction analysis, demonstrating the strong effect of dispersion forces and electrostatic interactions on the adsorption and interaction energy, being more stable the heteroaromatic cases. The electronic structure and semiconductor properties of Guest@MOF complexes have proved that heteroaromatic guest molecules allow band-gap tuning, depending on the electron donor and acceptor character of the guest molecules. Simulated absorption spectra of Guest@MOF complexes preserved the same profile because of the higher contribution of MOF, but heteroaromatic complexes displayed interesting cases of Charge−Transfer excitations, generating new bands at lower energy. The Charge−Transfer spectra have exhibited the active participation of the Guest molecule in Charge−Transfer excitations, but the electronic Redistribution has played the key role in the global spectrum of Guest@MOF complexes. Incorporating heteroaromatic guest molecules appeared as an outstanding strategy to tune-up the MOF electronic properties.

Nature of Interlayer Bonds in Two-Dimensional Materials

The role of interlayer bonds in the two-dimensional (2D) materials "beyond graphene" and so-called van der Waals heterostructures is vital, and understanding the nature of these bonds in terms of strength and type is essential due to a wide range of their prospective technological applications. However, this issue has not yet been properly addressed in the previous investigations devoted to 2D materials. In our work, by using first-principles calculations we perform a systematic study of the interlayer bonds and charge redistribution of several representative 2D materials that are traditionally referred as van der Waals systems. Our results demonstrate that one can distinguish three main types of inter-layer couplings in the considered 2D structures: one atom thick membranes bonded by London dispersion forces (graphene, hBN), systems with leading electrostatic interaction between layers (diselenides, InSe and bilayer silica) and materials with so-called dative or coordination chemical bonds between layers (ditelurides). We also propose a protocol for recognising the leading type of interlayer bonds in a system that includes comparison of interlayer distances, binding energies and redistribution of the charge densities in interlayer space. Such an approach is computationally cheap and can be used to further prediction of chemical and physical properties such as charge density waves (CDW), work function and chemical stability at ambient conditions.

CONTRIBUTIONS OF LAKATOSIAN THEORY TO THE EVALUATION OF EXPLANATORY MODELS OF INTERMOLECULAR FORCES MADE BY UPPER-SECONDARY SCHOOL STUDENTS

The focus of the present study is the learning processes of concepts related to hydrogen bonds, which were developed using a didactic sequence (DS). Based on the perspective of Imre Lakatos, it was observed whether the explanatory models created by upper-secondary students form progressive transition sequences, which are similar to what Lakatos, in his text The History of Science, calls a “problem” that increases the explanatory/heuristic power of the model. To evaluate the evolution of these models, which generally consist of progressive transitions, four phases were developed: 1) the categorization of answers obtained in the DS in Realist, Empiricist or Rationalist zones, as well as an attribution of scores; 2) the determination of a score range for said zones; 3) hierarchical cluster analysis (HCA) and 4) an analysis of the progressive transition of the explanatory models. A continuous review of the ideas expressed by the students during their learning of the subject revealed that a significant share of students progressed conceptually. In a general way, it can be said that the activities developed in the DS contributed substantially to the progressive transition of the explanatory models made by most students. Furthermore, the approach of the DS toward the subject of hydrogen bonds allowed the students to interpret the phenomena studied using their knowledge of Chemistry. Keywords: London force and dipole-dipole interactions, progressive transition, chemistry teaching

Using Different Surface Energy Models to Assess the Interactions between Antiviral Coating Films and phi6 Model Virus.

High molecular weight chitosan (HMWCh), quaternised cellulose nanofibrils (qCNF), and their mixture showed antiviral potential in liquid phase, while this effect decreased when applied to facial masks, as studied in our recent work. To gain more insight into material antiviral activity, spin-coated thin films were prepared from each suspension (HMWCh, qCNF) and their mixture with a 1:1 ratio. To understand their mechanism of action, the interactions between these model films with various polar and nonpolar liquids and bacteriophage phi6 (in liquid phase) as a viral surrogate were studied. Surface free energy (SFE) estimates were used as a tool to evaluate the potential adhesion of different polar liquid phases to these films by contact angle measurements (CA) using the sessile drop method. The Fowkes, Owens-Wendt-Rabel-Kealble (OWRK), Wu, and van Oss-Chaudhury-Good (vOGC) mathematical models were used to estimate surface free energy and its polar and dispersive contributions, as well as the Lewis acid and Lewis base contributions. In addition, the surface tension SFT of liquids was also determined. The adhesion and cohesion forces in wetting processes were also observed. The estimated SFE of spin-coated films varied between mathematical models (26-31 mJ/m2) depending on the polarity of the solvents tested, but the correlation between models clearly indicated a significant dominance of the dispersion components that hinder wettability. The poor wettability was also supported by the fact that the cohesive forces in the liquid phase were stronger than the adhesion to the contact surface. In addition, the dispersive (hydrophobic) component dominated in the phi6 dispersion, and since this was also the case in the spin-coated films, it can be assumed that weak physical van der Waals forces (dispersion forces) and hydrophobic interactions occurred between phi6 and the polysaccharide films, resulting in the virus not being in sufficient contact with the tested material during antiviral testing of the material to be inactivated by the active coatings of the polysaccharides used. Regarding the contact killing mechanism, this is a disadvantage that can be overcome by changing the previous material surface (activation). In this way, HMWCh, qCNF, and their mixture can attach to the material surface with better adhesion, thickness, and different shape and orientation, resulting in a more dominant polar fraction of SFE and thus enabling the interactions within the polar part of phi6 dispersion.

London Dispersion Effects in a Distannene/Tristannane Equilibrium: Energies of their Interconversion and the Suppression of the Monomeric Stannylene Intermediate.

Reaction of {LiC6 H2 -2,4,6-Cyp3 ⋅Et2 O}2 (Cyp=cyclopentyl) (1) of the new dispersion energy donor (DED) ligand, 2,4,6-triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6 H2 -2,4,6-Cyp3 )2 }2 (2), and the cyclotristannane {Sn(C6 H2 -2,4,6-Cyp3 )2 }3 (3). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol-1 and ΔS=0.102 kcal mol-1 K-1 , which gives a ΔG300 K =+2.86 kcal mol-1 , showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is -28.5 kcal mol-1 per {Sn(C6 H2 -2,4,6-Cyp3 )2 unit, which exceeds the DED energy in 2 of -16.3 kcal mol-1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results).

London Dispersion Effects in a Distannene/Tristannane Equilibrium: Energies of their Interconversion and the Suppression of the Monomeric Stannylene Intermediate

AbstractReaction of {LiC6H2−2,4,6‐Cyp3⋅Et2O}2 (Cyp=cyclopentyl) (1) of the new dispersion energy donor (DED) ligand, 2,4,6‐triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6H2−2,4,6‐Cyp3)2}2 (2), and the cyclotristannane {Sn(C6H2−2,4,6‐Cyp3)2}3 (3). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol−1 and ΔS=0.102 kcal mol−1 K−1, which gives a ΔG300 K=+2.86 kcal mol−1, showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is −28.5 kcal mol−1 per {Sn(C6H2−2,4,6‐Cyp3)2 unit, which exceeds the DED energy in 2 of −16.3 kcal mol−1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results).

Wear performance under dry and lubricated conditions of duplex treatment TiN/TiCrN coatings deposited with different numbers of CrN interlayers on steel substrates

Cold work steels are used in harsh conditions including high load, wear, corrosion, and mechanical stresses that can easily lead to degradation and wear of the material. Generally, multilayer ceramics coatings are attractive candidates to develop engineering components by combining positive characteristics of different coatings. In this study, the TiN/TiCrN coatings with the different number of CrN interlayers were successfully deposited on nitrided and non-nitrided DIN 1.2379 steel, and their wear behavior was investigated at dry and lubrication conditions under different loads. The relationship between coating architectures and coating characteristics was explored. The microstructure and composition of the specimens were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX) and Atomic force microscopy (AFM).The nano-hardness were measured by nanoindenter, respectively. The adhesion and tribological behavior were evaluated using the Rockwell-C indentation and reciprocating tribometer tests, respectively. The results reveal that the nitrided samples with the TiN/TiCrN coatings with the different number of CrN interlayer showed much better wear resistance than the non-nitrided coatings at dry conditions. On the other hand, nitrided and nitride + coated TiN/TiCrN with the different number of CrN interlayer specimen showed better wear resistance at lubricated conditions. In addition, the fact that uncoated and nitrided steels have higher wear resistance at lubricated conditions than coated samples shows that TiN/TiCrN coatings are not proper even with a lubricant additive over a certain load value.

Crystal Structure, Hirshfeld Surface Analysis, and Computational Study of Quinolin-8-yl 4-Chlorobenzoate: Insights from Spectroscopic, Thermal, and Antitumor Properties

We report the time-efficient synthesis of quinolin-8-yl 4-chlorobenzoate (3) via an O-acylation reaction between 8-hydroxyquinoline (1) and 4-chlorobenzoyl chloride (2) mediated by triethylamine in acetonitrile under heating at 80 °C for 20 min in the Monowave 50 reactor. This protocol is distinguished by its short reaction time, operational simplicity, and clean reaction profile. The structure of 3 was fully characterized through a combination of analytical techniques, including NMR, IR, and UV–Vis spectroscopy, MS spectrometry, differential scanning calorimetry (DSC), thermogravimetry (TG), and crystallographic studies. Interestingly, X-ray diffraction analyses of 3 show that the crystal structure is characterized by C-H···N, C-H···O, Cl···π, and π···π interactions. The molecular conformation presents an orthogonal orientation between aromatic rings in the solid state. The calculated interaction energies using the CE-B3LYP model show that dispersion forces act in a higher proportion to build the crystal, which is consistent with the few short hydrogen interactions detected. Electrostatic potential maps suggest the formation of σ-holes over the Cl atoms. Although they can behave as both Lewis acid and base sites, Cl··Cl interactions are absent due to the shallow depth of these σ-holes. Quantum chemical descriptors and global reactivity descriptors were examined using the B3LYP method with the 6-31G(d,p) basis set implemented in CrystalExplorer. Finally, compound 3 exhibited low activity against HOP-92 and EKVX non-Small-cell lung and UO-31 Renal cancer cell lines, with a growth inhibition percentage (GI%) ranging from 6.2% to 18.1%.

Influence of Particle Geometry on Dispersion Forces

Dispersion forces (van der Waals force and Casimir force) originating from quantum fluctuations are crucial in the cohesion of microscale and nanoscale particles. The nonadditivity of these forces and the complex geometry of realistic particles make conventional additive algorithms produce unacceptable errors, and it is experimentally challenging to identify the contribution of dispersion forces from the many forces that constitute the cohesion. In this study, we use the fluctuating surface current technique, an exact scattering theory-based nonadditive algorithm, to accurately quantify the influence of geometry on dispersion forces. To characterize the complex geometries, we employ a data-adaptive spatial filtering method and three-level descriptors. Our results determine the influence of multiscale surface fluctuations on dispersion forces. Additionally, we establish a convenient formula for predicting the dispersion forces between realistic particles with complex shapes from the exact Lifshitz solution via multistage corrections.

Impact of surface roughness, surface charge, and temperature on sandstone wettability alteration by nanoparticles

The wettability of rocks affects the balance between capillary and viscous forces during multiphase flow through porous media, which in turn determines the fluid displacement process governing the recovery of oil from subsurface formations. In this work, the mechanism of wettability reversal of aged synthetic sandstones by metal oxide nanoparticles (SiO2 and Al2O3) was investigated with particular focus on the impact of surface roughness, zeta potential, and temperature. The synthetic surfaces were prepared from powders of Berea sandstone with known grain size ranges and their average roughness and roughness ratio were obtained from the 3D surface reconstruction of their microscope images. Each surface was subsequently aged in Permian crude oil to alter its wettability. For surfaces with larger grain sizes and lower surface roughness ratios, the lower capillary pressure allowed stronger oil/surface interactions, leading to enhanced oil-wetness. The wettability alteration effects of nanoparticles were then examined through real-time top view imaging and dynamic front view contact angle experiments. The negatively charged SiO2 nanoparticles rapidly reversed the sandstone wettability, indicating their potential applicability as wettability alteration agents. By contrast, the positively charged Al2O3 counterpart caused no wettability reversal. The mechanism of wettability alteration was further studied by microscale interaction analyses and nanoscale transmission electron microscopy. Because nanoparticles were only a few nanometers large, the microscale roughness had a negligible effect on the wettability reversal. Instead, the combined effect of van der Waals dispersion forces and surface-charge-induced electrostatic forces were recognized as the two key factors affecting the wettability of sandstone particles. Such interactions may be curbed at elevated temperatures due to a decrease in the zeta potential and colloidal stability of the particles.