Minimum Interaction Energy Research Articles

Simulation of adsorption behavior for various functionalized graphene nanosheets containing alkyl chain/polymer nanocomposites using ReaxFF

The non-covalent interactions in polymer/functionalized graphene nanosheet (FGN) nanocomposites containing the alkyl chain were investigated in this study. For this purpose, the non-covalent interactions at the interfaces of the mentioned polymer nanocomposites were accurately assessed using reactive molecular dynamics (RMD) simulation. The considered structures included poly(3-(4-n-octyl)-phenylthiophene) (POPT) and poly(3-phenylhydrazone thiophene) (PPHT) with FGNs featuring primary amine (PA), secondary amine (SA), alkanolamine (AA), and diamine (D) functional groups in alkyl chain. The functional groups varied in alkyl chain lengths via n (n equal to carbon atoms). Results from RMD simulations highlighted that the minimum interaction energy occurred between polymers and G-SA 1 %. PPHT exhibited strong interactions with G-D-4 1 % and G-PA-16 1 %. Contrary to other FGN, especially G-PA 1 %, increasing alkyl chain length in G-SA 1 % negatively affected polymers/G-SA 1 % interaction energy. Moreover, Hydrogen bonding (H-bonding) was examined in all different nanocomposites of PPHT/FGN. Also, the effect of an increase in coverage percentage and temperature was evaluated. These findings offer valuable insights into interactions of polymer-FGN with different alkyl chain lengths, aiding in the design of tailored nanocomposites.

Thermal behavior of cyclodextrin/adamantane host/guest inclusion complex in an aqueous media

Understanding the thermal behavior of cyclodextrin/adamantane (CD/Ad) host/guest inclusion complex, and the effect of CD type, i.e., α, β, and γ, on their hybridization are fundamentally attractive to find broad contemporary applications toward improving efficient drug delivery systems. In this work, β-cyclodextrin was found as the best host to capture the Ad guest with the minimum intermolecular interaction energy of −11.996 ± 0.026 kcal/mol. This behavior was due to the perfect size match of adamantane with a diameter of 6.49 Å into β-cyclodextrin. It was observed that adamantane was supported by all sides of the inner wall of β-cyclodextrin, while the guest interacted with only one side of the inner wall of γ-cyclodextrin. The results proved that rising the solution temperature has prevented the formation of a host/guest inclusion complex, at the temperature range of 330–340 K. Deep molecular view into the solubility of adamantane showed that the failure of non-bonded interactions of CD-Ad with temperature led to the entrance of water molecules into the hollow part of the β-cyclodextrin created an obstacle against the entrance of the guest. According to the interactional achievements, the electrostatic contribution of the host-water and the dispersive contribution of guest-water led to reducing the interaction energy of host–guest with the temperature. The present research offers some insight into the design of β-cyclodextrin/adamantane-based host/guest assemblies to form a thermoreversible hydrogel in an aqueous media.

Continuum modeling for lithium storage inside nanotubes

Lithium storage and capture are of particular importance for the development of new technology in electric vehicles and portable electronics. Nanotubes (NTs) are among many porous nanomaterials offered as potential candidates for lithium storage. In this paper, we adopt a continuum approach together with the Lennard–Jones function to determine the minimum interaction energies for lithium atoms in boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs). By minimizing the interaction energies, we may obtain the preferred type and size of the nanotubes to encapsulate the lithium atoms. The results showed that BNNTs and CNTs are attractive candidates for lithium atom encapsulation, and the optimal nanotube to enclose lithium is the BNNT with a radius equal to 3.4 Å, and corresponding (5, 5) armchair nanotubes and (9, 0) zigzag nanotubes, where the minimum energy is obtained. The present computations observed that both nanotubes are promising candidates for lithium intercalation materials suitable for battery applications.

Phosphate-solubilizing microorganisms regulate the release and transformation of phosphorus in biochar-based slow-release fertilizer

Coupling phosphate-solubilizing microorganisms (PSM) can improve the availability of phosphorous (P) in biochar-based slow-release P fertilizers (BPF). However, the mechanism in release and transformation of P in BPF regulated by PSM is still unclear. Herein, the biocompatibility and the adhesion behaviors of BPF and PSM (Enterobacter hormaechei Rs-198) in soil were firstly studied, and a 90 days' laboratory-scale soil incubation experiment of BPF and Rs-198 was performed to study the transformation of P of BPF. The results show that BPF has a good biocompatibility for Rs-198 due to its low aromaticity, graphitization and free radicals' content (0.084 mg/g). Rs-198 are adhered to the surface of BPF in soil due to the high negative secondary energy minimum and low total interaction energy between Rs-198 and BPF. Available P in the incubation of BPF and Rs-198 (BR treatment) is significantly higher than that of the incubation of BPF (BF treatment) at initial 60 days. However, the content of available P in BR treatment is much lower compared with that in BF treatment on day 90, which is attributed to the entrapment of released P from BPF by Rs-198 and the formation of polyphosphate (polyP) rather than bound with soil mineral. Overall, this study presents new insights into the transformation of P in BPF regulated by PSM.

Precise portrayal of microscopic processes of wastewater biofilm formation: Taking SiO2 as the model carrier

Precise characterization of the microscopic processes of wastewater biofilm formation is essential for regulating biofilm behavior. Nevertheless, it remains a great challenge. This study investigated biofilm formation on SiO2 carriers under gradually increasing shear force combining the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory in a Couette-Taylor reactor, and precisely revealed the micro-interface interaction and species colonization during biofilm formation. The results indicated that bacterial reversible adhesion distance on SiO2 carrier surface was 3.06 ± 0.48 nm. Meanwhile, the secondary minimum of total XDLVO interaction energy could be used as a novel indicator to distinguish biofilm formation stages. The revealed biofilm formation stages were also confirmed by the electrochemical analysis. Additionally, the pioneer species that colonized at first were Comamonadaceae, Azospira, Flavobacterium and Azonexus, while keystone species such as Hydrogenophaga, AKYH767, Aquimonas and Ignavibacterium determined the stability of microbial community. In conclusion, this study provided a methodological example to study wastewater biofilm micro-interface behavior through the integration of an experimental platform as well as multiple monitoring and analysis methods, which opened up new perspectives for biofilm research and provided useful guidance for the regulation of biofilm-related treatment processes and new technology development.

Synthesis, characterization, in-silico, and in-vitro biological studies of Cu(II), Zn(II) complexes of semicarbazone, thiosemicarbazone derivatives of dehydrozingerone

Treatment of multidrug resistance pathogens has been a challenge for several decades. Herein, we report a novel Cu(II) and Zn(II) complexes of dehydrozingerone derivatives of semicarbazone and thiosemicarbazone. The semicarbazone and thiosemicarbazone derivative ligands were prepared by a modified method with better yield using aldol condensation. The prepared ligands and their metal complexes were characterized with spectroscopic methods (UV, IR, 1H-NMR, 13C-NMR, and DEPT-135), molar conductivity measurements, and thermogravimetric analysis (TGA). The compounds were assessed for antibacterial and antioxidant potential by following the disk diffusion and DPPH methods, respectively. The antimicrobial assay results show that ligands (L1 & L2) show lower to medium mean inhibition zones from 3.5 ± 0.00 -10.86 ± 0.82 mm at 100 µg/mL and 200 µg/mL. The complexes exhibited better antibacterial potential (7.44 ± 0.55 -15.44 ± 0.31 mm) as compared to ligands alone. Also, the complexes exhibited better percent antioxidant potential than both ligands. Furthermore, in silico docking data of compounds on Staphylococcus aureus gyrase confirms the prepared compounds are potential molecules with minimum interaction energy from – 7.6 to – 9.1 kcal/mol. The highest result was achieved by [Zn(L1)2(H2O)2] complex (– 9.1 kcal/mol). Therefore, the structural modification of dehydrozingerone to semicarbazone and thiosemicarbazone derivatives, and subsequent complexation with metals can enhance biological potentials.

Elastic interaction energy analysis during twin plane formation in the martensitic transformation process of α"-martensite in Ti-Nb-Al

To understand the twin selection mechanism that occurs in the initial stage of the martensitic transformation of shape memory alloys, the stress state during twin plane formation was numerically analyzed by micromechanics. The self-accommodation microstructure of α''-martensite of the Ti-23Nb-3Al (at%) shape memory alloy, in which the lattice parameter was adjusted to eliminate the formation of internal twinning due to lattice-invariant deformation, was adopted for analysis. The two lattice correspondence variants (CVi and CVj) formed a twin plane. CVi was assumed to be spheroid, and the elastic strain energy during twin plane formation was evaluated by analyzing the elastic interaction energy when CVj formed around CVi. There are three types of twins ({011}α" compound twin, {111}α" type I twin, and <211>α" type II twin) in the self-accommodation microstructure of α"-martensite. Regardless of the CVi geometry (i.e., aspect ratio (1 to 0.01) and minor axis orientation), the {111}α" type I twin exhibited minimum elastic interaction energy, indicating that minimum elastic strain energy was generated during this twin plane formation. This result is consistent with the experimental results, which showed the selective formation of {111}α" type I twins in the initial stage of martensitic transformation.

Density Functional Theory Study of Intermolecular Interactions between Amylum and Cellulose

Amylum is one of the polysaccharides developed into biodegradable plastic bags. However, amylum-based plastics are easily damaged due to their low mechanical strength and hydrophilic properties. Cellulose is used as a support material in amylum-based plastics to increase strength and reduce water damage. This study investigated the molecular interactions between amylum and cellulose computationally. The minimum interaction energy of amylum and cellulose was calculated using in silico modeling using the Density Functional Theory (DFT) method. The B3LYP function and the basis set 6-31++g** were used in the calculations. Simultaneously, D3 Grimme dispersion correction was used as the effect of water solvent in the measures. The results obtained from this study were the interaction energy of amylum and cellulose of –29.8 kcal/mol. The HOMO-LUMO energy gap of the cellulose-amylum complex was lower than cellulose, indicating that the cellulose-amylum complex was more reactive and bonded to each other. Analysis of Natural Bond Orbital (NBO), Quantum Theory Atom in Molecule (QTAIM), Reduced Density Gradient (RDG), Non-covalent Interaction Index (NCI), and Intrinsic Bond Strength Index (IBSI) showed that the cellulose-amylum complex had weak to medium intermolecular bonds. The hydrogen bond at O61···H48 was the strongest in the complex. All data show that cellulose and amylum could interact through non-covalent bonds.

Magnetic drive micro/nanomotor model

A model of a micro-/nanomotor with a hydrodynamic mechanism of motion due to the action of a rotating uniform external magnetic field is proposed. Micro-/nanomotor - is a chain of three charged particles, one of which has a magnetic moment. The total charge of the system is zero. In the absence of an external field, the particles are in equilibrium due to the action of the forces of attraction and repulsion, which corresponds to the minimum interaction energy. After applying a rotating magnetic field, a particle with a magnetic moment begins to rotate, forming a flow in the surrounding viscous fluid. The flow induces a hydrodynamic force that moves the chain in a specific direction. The forces of hydrodynamic interaction of particles with each other are taken into account, as well as internal forces holding the particles together. The dynamics of six model aggregates with one rotating particle is simulated numerically. The proposed mechanism for moving the chain can be used in the design of micro-/nanomotors and control them to deliver the payload.

Modeling Interactions of Iron Atoms Encapsulated in Nanotubes

The behavior and electronic structure of the carbon and boron nitride nanotubes that interact with the iron atom were studied using the Lennard–Jones potential and hybrid discrete-continuum approach. The iron-filled nanotubes were explored by means of classical applied mathematics in order to develop an understanding of the underlying mechanisms of the encapsulation of metal atoms inside nanotubes. Herein, we examined the suction energy and then the equilibrium offset positions of the iron atoms inside zigzag and armchair single-walled nanotubes, to obtain the optimal radii of the tubes and encapsulate the iron atom by determining the radii that provide the minimum interaction energies. Our observations indicate that the encapsulation behaviour depends on the radii of the nanotubes, and we predict that it is less likely for an iron atom to be enclosed inside the nanotubes when the value of the tube radius is less than ≈2.5 Å. The optimal nanotube necessary to fully enclose the iron atom has a radius of ≈4.2 for both carbon and boron nitride nanotubes, which approximately corresponds to the interaction energies of −1.8 kcal/mol. In its entirety, this work presents an approach that might further the understanding of the encapsulation of metal atoms inside nanotubes.

MOLECULAR DESIGN OF N-ACYL DERIVATIVES OF 2-(2-OXOPYROLIDIN-1-YL)-ACETAMIDE WITH GABA-ERGIC AND GLUTAMATERGIC ACTIVITIES

The first of the most successfully implemented nootropic drugs in medical practice is piracetam, which should be attributed to cyclic derivatives of gamma-aminobutyric acid. The production of new piracetam derivatives with high nootropic activity is a promising direction in the development of new neuroprotective drugs.The aim of the study is to predict GABA-ergic and glutamatergic activities of N-acyl derivatives of 2-(2-oxopyrolidin-1-yl)- acetamide by a molecular docking method through the energy analysis of interaction of modeled structures with GABAA and AMPA receptors with their subsequent targeted synthesis.Materials and methods. The objects of the research are new N-acyl derivatives of 2-oxo-1-pyrrolidineacetamide and a virtual model of the GABAA receptor of the Homo sapiens organism with the identification code 6D6U and a three-dimensional model of the AMPA-receptor of the Rattus norvegicus organism with the identification code 3LSF from the RCSB PDB database. The simulated compounds were designed in the HyperChem 8.0.8 program. This program was also used to optimize geometry using the force field of molecular mechanics MM+. Molecular docking was carried out using the Molegro Virtual Docker 6.0.1 program. The preparation of N-acyl derivatives of 2-(2-oxopyrrolidin-1-yl)-acetamide was carried out by the interaction of 2-(2-oxopyrrolidin-1-yl)-acetamide with an excess of the corresponding anhydride under conditions of acid catalysis.Results. Based on the results of molecular docking, a high affinity of all simulated compounds for the binding site of GABAA and AMPA receptors can be estimated. According to the predict, the maximum GABA-ergic activity should be expected for (N-[2-(2-oxopyrrolidin-1-yl)-acetyl]-butyramide. N-acyl derivatives of 2-oxo-1-pyrrolidineacetamide form a more stable complex with amino acid residues Arg207, Phe200, Thr202, Tyr97, Tyr157, Tyr205 and Phe65 of the GABAA receptor binding site than the GABA molecule. In terms of the minimum interaction energy, the N-acyl derivatives of 2-(2-oxopyrrolidin-1-yl)- acetamide are superior to a number of known ligands such as GABA, piracetam, anipiracetam, picamilon and pramiracetam. The tested compounds have also shown a high affinity for the binding site of the AMPA receptor. The leader compound is also the compound PirBut, as in the case of the GABAА receptor.Conclusion. Molecular modeling of the ligands interaction with the active binding site of gamma-aminobutyric acid of the GABAA receptor by molecular docking showed that all virtual N-acyl derivatives of 2-oxo-1-pyrrolidineacetamide can exceed a number of nootropic drugs by activity. In the course of molecular design, a method for predicting a glutamatergic activity for 2-pyrrolidone derivatives has been developed. It suggests a significant nootropic activity for N-[2-(2-oxopyrrolidin-1-yl)- acetamide amides.

In silico virtual screening of lead compounds for major antigenic sites in respiratory syncytial virus fusion protein

Human respiratory syncytial virus (RSV) is a leading ubiquitous respiratory pathogen in newborn infants, young children, and the elderly, with no vaccine available to date. The viral fusion glycoprotein (RSV F) plays an essential role in the infection process, and it is a primary target of neutralizing antibodies, making it an attractive site for vaccine development. With this in view, there is a persistent need to identify selective antiviral drugs against RSV, targeting the major antigenic sites on the F protein. We aimed to conduct a robust in silico high-throughput drug screening of one million compounds to explore potential inhibitors that bind the major antigenic site Ø and site II on RSV F protein, which are the main target of neutralizing antibodies (NAb). We utilized the three-dimensional crystallographic structure of both antigenic site Ø on pre-F and antigenic II on post-F to screen for potential anti-RSV inhibitors. A library of one million small compounds was docked to explore lead binders in the major antigenic sites by using virtual lab bench CLC Drug Discovery. We also performed Quantitative Structure-Activity and Relationship (QSAR) for the lead best binders known for their antiviral activity. Among one million tested ligands, seven ligands (PubChem ID: 3714418, 24787350, 49828911, 24802036, 79824892, 49726463, and 3139884) were identified as the best binders to neutralizing epitopes site Ø and four ligands (PubChem ID: 865999, 17505357, 24802036, and 24285058) to neutralizing epitopes site II, respectively. These binders exhibited significant interactions with neutralizing epitopes on RSV F, with an average of six H bonds, docking energy of − 15.43 Kcal·mol−1, and minimum interaction energy of − 7.45 Kcal·mol−1. Using in silico virtual screening, we identified potential RSV inhibitors that bind two major antigenic sites on the RSV F protein. Using structure-based design and combination-based drug therapy, identified molecules could be modified to generate the next generation anti-RSV drugs.

Identification of potential natural inhibitors of the receptor-binding domain of the SARS-CoV-2 spike protein using a computational docking approach.

Background: The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the only zoonotic-origin CoV to reach the pandemic stage, to which neither an effective vaccine nor a specific therapy is available. The spike glycoprotein harbors the receptor-binding domain (RBD) that mediates the virus's entry to host cells. This study aimed to identify novel inhibitors that target the spike protein's RBD domain through computational screening of chemical and natural compounds. Method: The spike protein was modeled from the recently reported electron microscopy protein structure (PDB ID: 6VSB) and the previously described SARS-CoV protein structure (PDB ID: 6ACD and 6ACJ). Virtual lab bench CLC Drug Discovery was used to computationally screen for potential inhibitory effects of currently prescribed drugs (n = 22), natural antiviral drugs (n = 100), and natural compounds (n = 35032). Quantitative Structure-Activity Relationship (QSAR) studies were also performed to determine the leading binders known for their antiviral activity. Results: Among the drugs currently used to treat SARS-CoV2, hydroxychloroquine and favipiravir were identified as the best binders with an average of four H-bonds, with a binding affinity of − 36.66 kcal/mol and a minimum interaction energy of − 6.63 kcal/mol. In an evaluation of antiviral compounds, fosamprenavir and abacavir showed effective binding of five H-bonds, with an average binding affinity of − 18.75 kcal.mol− 1 and minimum interaction energy of − 3.57 kcal/mol. Furthermore, screening of 100 natural antiviral compounds predicted potential binding modes of glycyrrhizin, nepritin, punicalagin, epigallocatechin gallate, and theaflavin (average binding affinity of − 49.88 kcal/mol and minimum interaction energy of − 4.35 kcal/mol). Additionally, the study reports a list of 25 natural compounds that showed effective binding with an improved average binding affinity of − 51.46 kcal/mol. Conclusions: Using computational screening, we identified potential SARS-CoV-2 S glycoprotein inhibitors that bind to the RBD region. Using structure-based design and combination-based drug therapy, the identified molecules could be used to generate anti-SARS-CoV-2 drug candidates.

Balanced polarizable Drude force field parameters for molecular anions: phosphates, sulfates, sulfamates, and oxides.

Polarizable force fields are emerging as a more accurate alternative to additive force fields in terms of modeling and simulations of a variety of chemicals including biomolecules. Explicit treatment of induced polarization in charged species such as phosphates and sulfates offers the potential for achieving an improved atomistic understanding of the physical forces driving their interactions with their environments. To help achieve this, in this study we present balanced Drude polarizable force field parameters for molecular ions including phosphates, sulfates, sulfamates, and oxides. Better balance was primarily achieved in the relative values of minimum interaction energies and distances of the anionic model compounds with water at the Drude and quantum mechanical (QM) model chemistries. Parametrization involved reoptimizing available parameters as well as extending the force field to new molecules with the goal of achieving self-consistency with respect to the Lennard-Jones and electrostatic parameters targeting QM and experimental hydration free energies. The resulting force field parameters achieve consistent treatment across the studied anions, facilitating more balanced simulations of biomolecules and small organic molecules in the context of the classical Drude polarizable force field. Graphical abstract.

Comparative DFT Study of Parallel and Antiparallel Conformation of 5CB and 6CB Liquid Crystal Dimers

An investigation of the interaction of 5CB and 6CB liquid crystals along with their dimer configurations in different conformations. The total energy, thermal energy, HOMO-LUMO Gap, dipole moment, polarizability, constant volume heat capacity, entropy, zero-point energy (ZPE), and enthalpy of the different configurations of 5CB and 6CB liquid crystal dimers are affected during the molecular interaction. The different interaction properties of 5CB, 6CB, and 5CB-6CB dimers studied in parallel and antiparallel conformation with the help of density functional theory method lc-blyp by NWChem software package. The 5CB and 6CB liquid crystal dimers have the least dipole moment and negative entropy in the antiparallel conformation. The cross conformation of 5CB liquid crystal dimer (5CB-5CB) has the least isotropic polarizability; however, the parallel conformation of 5CB liquid crystal dimer has the highest isotropic polarizability. The isotropic polarizability is minimum in the antiparallel conformation of 6CB liquid crystal dimer (6CB-6CB), while isotropic polarizability is maximum in the parallel conformation of 6CB liquid crystal dimer. The 5CB liquid crystal dimer and 6CB liquid crystal dimer have minimum negative interaction energy in the antiparallel conformation, but 5CB-6CB liquid crystal dimer has positive interaction energy for all the possible conformations.

Modelling of Paclitaxel Conjugated with Carbon Nanotubes as an Antitumor Agent for Cancer Therapy.

Functionalized carbon nanoparticles (CNPs) show great promise for various drug delivery applications. These CNPs have distinct physical and chemical properties, such as low solubility, very high conductivity, and drug loading capability, and are thus important nanodevices for cancer therapy. Cancer is a highly challenging disease, because its therapy involves distinguishing diseased cells from healthy ones. This study aimed to determine the ability of CNPs conjugated with a chemotherapeutic agent to inhibit cancer cell growth. We developed two models to determine the effectiveness of paclitaxel (PTX) as an antitumor agent bonded to single-walled carbon nanotubes (SWCNTs) varying in radius (r). The models were used to mathematically evaluate the energy arising from the PTX-SWCNT interaction. The first model divided the PTX molecule into 15 subcomponents: 4 imidazole rings, 1 group of atoms forming a cylindrical nanotube, 6 methyl groups (small spheres represented as individual CH₃ molecules), 3 carboxyl groups (medium-sized spheres represented as individual CO₂ molecules), and 1 large sphere. In the second model, PTX was modeled as a spherical cage with a spheroidal structure. Next, we determined the minimum interaction energy between each subcomponent and an SWCNT of radius r, and then summed the interactions to determine the total energy (E). The numerical results indicated that SWCNTs can be loaded with PTX. We also determined the critical nanotube r required for acceptance of the PTX molecule. We believe that the findings of this research will encourage the development of new nanodevices capable of delivering larger amounts of drugs, genes, and proteins.

On the coagulation efficiency of carbonaceous nanoparticles

In this paper we derived the interaction energy between two spherical nanoparticles from the pair-wise Lennard-Jones attractive and repulsive potentials of the constituent atoms of the two particles, and proposed a coagulation efficiency model based on the average particle kinetic energy and the potential well depth (i.e. the minimum interaction energy) between two colliding particles. To test the performance of this new coagulation efficiency model, we applied it in detailed population balance modelling of soot particle size distributions (PSDs), and found better agreement with the measured PSDs in a benchmark premixed ethylene flame than that using the unit coagulation efficiency, especially in the range of small particles with mobility diameter less than 5 nm. Moreover, the agreement between the computed and the measured primary particle size distribution (PPSD) was also improved with the new coagulation efficiency model.

Theory of elastic constants of athermal amorphous solids with internal stresses

A new microscopic derivation of the elastic constants of amorphous solids is presented within the framework of nonaffine lattice dynamics, which makes use of a perturbative form of the low-frequency eigenvectors of the dynamical matrix introduced in Mazzacurati et al. (EPL 34:681–686, 1996). The theory correctly recovers the shear modulus at jamming, \(\mu \sim (z-2d)\), including prefactors in quantitative agreement with simulations. Furthermore, this framework allows us, for the first time, to include the effect of internal stresses. The theory shows that the Maxwell rigidity criterion \(z=2d\) is violated with internal stress. In particular, \(\mu \sim (z-2df)\) where \(f<1\) if the bonds are, on average, stretched, and the solid is thus rigid below the Maxwell isostatic limit, while \(f>1\) if the bonds are, on average, compressed. The coefficient f is derived in analytical form and depends only on d and on the average particle displacement from the interaction energy minimum.

Porous Alumina Ceramics Obtained by Particles Self-Assembly Combing Freeze Drying Method.

An innovative approach for fabricating porous alumina ceramics is demonstrated in this paper. The distinguished feature is that the construction of the porous structure stems from the interaction between ceramic particles, which is a poorly explored area. By tailoring the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy to the second minimum, the dilute ceramic slurry would be gelled by the weakly assembled particle network, and the assembled structure is conserved via a freeze drying strategy. The DLVO theoretical analyses revealed that the second minimum of interaction energy could be obtained when the counter-ion concentration in colloidal suspension is 1.5 × 10−2 mol/L. The properties of the as-assembled samples were compared with one produced by the conventional freeze drying method. Results showed that the self-assembly of alumina particles has a positive influence on micro structures. Unlike the laminar pores generated by the traditional freeze drying procedure, the assembled samples show homogeneously interconnected and hierarchical open pores which were stable even after a 24 h dwell time at 950 °C (open porosity is 79.19% for the slurry of vol 20% solid loading). Particularly, after sintering at 1550 °C for 2 h, open porosity (67.01%) of the assembled samples was significantly greater than that of their un-assembled counterparts (39.97%). Besides, the assembled sample shows a narrower pore size distribution and a relatively higher cumulative pore volume.

Modelling of Nickel Atoms Interacting with Single-Walled Nanotubes

Herein, the encapsulation mechanism of nickel atoms into carbon and boron nitride nanotubes is investigated to determine the interaction energies between the nickel atom and a nanotube. Classical modelling procedures, together with the 6-12 Lennard-Jones potential function and the hybrid discrete-continuous approach, are used to calculate the interaction of a nickel atoms with(i,i)armchair and(i,0)zigzag single-walled nanotubes. Analytical expressions for the interaction energies are obtained to determine the optimal radii of the tubes to enclose the nickel atom by determining the radii that give the minimum interaction energies. We first investigate the suction energy of the nickel atom entering the nanotube. The atom is assumed to be placed on the axis and near an open end of a semi-infinite, single-walled nanotube. Moreover, the equilibrium offset positions of the nickel atoms are found with reference to the cross-section of the nanotubes. The results may further the understanding of the encapsulation of Ni atoms inside defective nanotubes. Furthermore, the results may also aid in the design of nanotube-based materials and increase the understanding of their nanomagnetic applications and potential uses in other areas of nanotechnology.