Large Negative Energy Research Articles

Insights of the Multimode Orientation-Dependent Initial Oxidation of Aluminum by First-Principles Theory Calculations.

A fundamental understanding of the oxidation mechanisms of aluminum (Al) alloys is of great importance for its applications in corrosion, catalysis, sensors, etc. In this work, we systematically investigated the first-stage oxidation behaviors of three low-index Al facets with O coverage up to two monolayers (ML) by using density-functional theory (DFT). The large negative adsorption energies indicated favorable oxidation on all three facets. However, distinctive structural and electronic changes induced by the adsorption of oxygen have led to different oxidation modes. More specifically, the oxidation process proceeded by "intercalating" into the subsurface region along the (111) plane out of the (110) facet with spontaneous O ingress into (110) far below one ML, as revealed by the electron density distribution, whereas the oxide ad-layer grew in a "layer-by-layer" mode on Al(111) and (001) facets. Moreover, various Al-O complexes with different atomic coordination numbers (CN), configurations, and sizes may be indicators of the tendency of an Al surface to be oxidized. Besides, the oxide phases formed on (111)/(001) and (110) assembled the Al-O bond distribution within α-Al2O3 and γ-Al2O3, respectively.

When strings surprise

We argue that on-shell excitations with large negative energies are created rapidly when the string coupling increases with time. This does not indicate an inconsistency in string theory since the negative energy on-shell excitation is always entangled with an on-shell excitation with a positive energy. The total energy of this energy-EPR state vanishes. We discuss the reason the energy-EPR states appear in string theory and the role they might play in black hole physics.

Existence of infinitely many weak solutions to Kirchhoff–Schrödinger–Poisson systems and related models

In this article we investigate the existence of infinitely many weak solutions for Kirchhoff–Schrödinger–Poisson systems via the critical point theory. We obtain infinitely many large energy solutions and negative energy solutions of the system with superlinear nonlinearities by using the fountain theorem and the dual fountain theorem, respectively. Moreover, we establish the existence of infinitely many weak solutions of the problem with sublinear nonlinearities by applying the genus theory introduced by Krasnolsel’skii [Topological Methods in the Theory of Nonlinear Integral Equations (The Macmillan Company, New York, 1964)]. In particular, we do not use the classical Ambrosetti–Rabinowitz condition.

The universality of black hole thermodynamics

The thermodynamic properties of black holes — temperature, entropy and radiation rates — are usually associated with the presence of a horizon. We argue that any extremely compact object (ECO) must have the same thermodynamic properties. Quantum fields just outside the surface of an ECO have a large negative Casimir energy similar to the Boulware vacuum of black holes. If the thermal radiation emanating from the ECO does not fill the near-surface region at the local Unruh temperature, then we find that no solution of gravity equations is possible. In string theory, black holes microstates are horizonless quantum objects called fuzzballs that are expected to have a surface [Formula: see text] outside [Formula: see text]; thus the information puzzle is resolved while preserving the semiclassical thermodynamics of black holes.

Defect mechanisms, oxygen vacancy trapping ability in rare‐earth doped BaTiO3 from first‐principles and thermodynamics

AbstractThe defect mechanisms of rare earth (RE) doped BaTiO3 have a strong impact on the electrical performance of the multilayer ceramics capacitors (MLCCs). Oxygen vacancy is the main reason for the device degradation over longtime use, while the effect of the doping strategy on controlling the oxygen vacancies is not yet quantitatively understood. In this work, the grand canonical thermodynamic defect model based on first‐principle calculations is applied to evaluate the defect mechanism of RE‐doped BaTiO3 under practical experimental condition. The charge compensation and prior site occupancy of RE are found not only associated with ionic size but also exhibit transitions with oxygen partial pressure and doping concentration. Furthermore, the oxygen vacancy trapping ability of RE ions is evaluated from the perspectives of thermodynamics and kinetics. The migration barrier among first nearest oxygen sites dramatically changed depending on the RE site occupancy. The large trapping ability is contributed by the relatively large negative binding energy of the defect complex and comparable RE concentrations substituted on Ba and Ti sites. The two conditions can be achieved in amphoteric ions doped systems, while in pure donor doped BT only one of these conditions can be satisfied. Although the self‐compensated defect complexes exhibit the highest binding energy, the trapping ability contributed by different defect complexes (, , REBa − RETi) is generally comparable in these systems. This feature of amphoteric RE ions accounts for the improvement of the lifetime and reliability of MLCCs.

Binding mechanism of perphenazine/thioridazine with acetylcholinesterase: Spectroscopic surface plasmon resonance and molecular docking based analysis

Alzheimer's disease (AD) causes dementia in most elderly individuals with cognitive and behavioral problems due to cholinergic synapse dysfunction. Thioridazine (TRZ) and perphenazine (PPZ) likely affect the acetylcholine (ACh) receptor and acetylcholinesterase (AChE) in the central nervous system (CNS) and improve the cholinergic system. This study aimed to determine the inhibitory effects of TRZ and PPZ on AChE using surface plasmon resonance (SPR) and molecular docking techniques to gain insight into the possible interaction mechanism between these medications and the enzyme. The SPR results indicated a high affinity of TRZ/PPZ to AChE (KD < 1 × 10−6 M). According to SPR results, increasing temperature decreases PPZ's binding strength to AChE while increasing the affinity of TRZ. Thermodynamic parameters demonstrated that hydrophobic interactions and hydrogen bonding are the main intermolecular forces between TRZ/PPZ and AChE. The results of the docking analysis were in good agreement with the experimental data, confirming only one binding site on AChE for TRZ and PPZ. PPZ showed a strong attachment to AChE due to its large negative binding energy (−10.58 kcal/mol). PPZ showed lower IC50 values toward AChE and TRZ, indicating a greater inhibitory effect on AChE.

Cracking Ion Pairs in the Electrical Double Layer of Ionic Liquids

Here we investigate a limiting case of the theory for aggregation and gelation in the electrical double layer (EDL) of ionic liquids (ILs). The limiting case investigated only accounts for ion pairs, ignoring the possibility of larger clusters and a percolating ionic network. This simplification, permits analytical solutions for the properties of the EDL. The resulting equations demonstrate the competition between the free energy of an association and the electrostatic potential in the EDL. For small electrostatic potentials and large negative free energies of associations, ion pairs dominate in the EDL. Whereas, for electrostatic potential energies larger than the free energy of an association, electric-field-induced cracking of ion pairs occurs. The differential capacitance for this consistent ion pairing theory has a propensity to have a “double hump camel” shape. We compare this theory against previous free ion approaches, which do not consistently treat the reversible associations in the EDL.

Large interfacial relocation in RBD-ACE2 complex may explain fast-spreading property of Omicron

The Omicron variant of SARS-CoV-2 emerged in South African in late 2021. This variant has a large number of mutations, and regarded as fastest-spreading Covid variant. The spike RBD region of SARS-CoV-2 and its interaction with human ACE2 play fundamental role in viral infection and transmission. To explore the reason of fast-spreading properties of Omicron variant, we have modeled the interactions of Omicron RBD and human ACE2 using docking and molecular dynamics simulations. Results show that RBD-ACE2 binding site may drastically relocate with an enlarged interface. The predicted interface has large negative binding energies and shows stable conformation in molecular dynamics simulations. It was found that the interfacial area in Omicron RBD-ACE2 complex is increased up to 40% in comparison to wild-type Sars-Cov-2. Moreover, the number of hydrogen bonds significantly increased up to 80%. The key interacting residues become also very different in Omicron variant. The new binding interface can significantly accommodate R403, as a key RBD residue, near ACE2 surface which leads to two new strong salt bridges. The exploration of the new binding interface can help to understand the reasons of high transmission rate of Omicron.

Why Do Liquids Mix? The Mixing of Protic Ionic Liquids Sharing the Same Cation Is Apparently Driven by Enthalpy, Not Entropy.

We study hydrogen bond (HB) redistribution in mixtures of two protic ionic liquids (PILs) sharing the same cation: triethylammonium methanesulfonate ([TEA][OMs]) and triethylammonium trifluoromethanesulfonate ([TEA][OTf]). The mixtures exhibit large negative energies of mixing. Based on results obtained from atomic detail molecular dynamics (MD) simulations, we derive a lattice model, discriminating between HB and nonspecific intermolecular interactions. We demonstrate that due to the ordered structure of the PILs, mostly the HB interactions contribute to the mixing energy. This allows to us to connect the equilibrium of HBs to each of the two anion species with the corresponding excess energies and entropies. The entropy associated with HB redistribution is shown to be negative, and even overcompensating the positive entropy associated with a statistical distribution of the ions in the mixture. This is strongly suggesting that the mixing process is driven by enthalpy, not entropy.

A note on construction of nonnegative initial data inducing unbounded solutions to some two-dimensional Keller–Segel systems

&lt;abstract&gt;&lt;p&gt;It was shown that unbounded solutions of the Neumann initial-boundary value problem to the two-dimensional Keller–Segel system can be induced by initial data having large negative energy if the total mass $ \Lambda \in (4\pi, \infty)\setminus 4\pi \cdot \mathbb{N} $ and an example of such an initial datum was given for some transformed system and its associated energy in Horstmann–Wang (2001). In this work, we provide an alternative construction of nonnegative nonradially symmetric initial data enforcing unbounded solutions to the original Keller–Segel model.&lt;/p&gt;&lt;/abstract&gt;

Ca coated B40 fullerene: A promising material for CO2 storage and separation

Density functional theory calculations were used to investigate the adsorption behavior of Ca coated B40 fullerene toward CO2 molecules. It was found that Ca atoms are unlikely to form clusters on B40. CO2 molecules can be effectively adsorbed on the Ca coated B40, as evidenced by large negative adsorption energies and significant charge transfer effects. Each Ca atom on B40 may adsorb four CO2, with an average adsorption energy of −0.54 eV which falls within the range proposed for an ideal CO2 adsorbent. Furthermore, Ca coated B40 exhibits high selectivity for CO2 from CO2/N2, CO2/H2, and CO2/CH4 gas mixtures.

Negative energy enhancement in layered holographic conformal field theories

Using a holographic model, we study quantum field theories with a layer of one CFT surrounded by another CFT, on either a periodic or an infinite direction. We study the vacuum energy density in each CFT as a function of the central charges, the thickness of the layer(s), and the properties of the interfaces between the CFTs. The dual spacetimes in the holographic model include two regions separated by a dynamical interface with some tension. For two or more spatial dimensions, we find that a layer of CFT with more degrees of freedom than the surrounding one can have an anomalously large negative vacuum energy density for certain types of interfaces. The negative energy density (or null-energy density in the direction perpendicular to the interface) becomes arbitrarily large for fixed layer width when the tension of the bulk interface approaches a lower critical value. We argue that in cases where we have large negative energy density, we also have an anomalously high transition temperature to the high-temperature thermal state.

Predicting adsorption behavior and anti-inflammatory activity of naproxen interacting with pure boron nitride and boron phosphide fullerene-like cages

The adsorption of naproxen (NPX) on surface of the boron phosphide (BP) and boron nitride (BN) fullerene-like cages have been studied and discussed by using density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations. Adsorption results using DFT demonstrated that B12N12 have strong interactions with the carbonyl (-C = O) group of naproxen via covalent bonding, while the interaction of the naproxen through a carbonyl and hydroxyl groups with the B12P12 occurred via electrostatic interactions, suggesting a large desorption time due to a large negative adsorption energy. The effects of hydroxyl (OH) functionalization on the adsorption of NPX via B12N12 has also been investigated. Results reveal that OH functionalization decreases the absolute Eb value of NPX on studied B12N12 fullerene-like cage. Theoretical studies also demonstrated the frequency shifts that is happening because of the adsorption process. The electronic and optical properties of B12N12 and OH-B12N12 in the presence of NPX are significantly sensitive. Interaction results demonstrated that B12N12 with H-donor functional groups such as –OH was effective for the delivery of naproxen as it leads to an increased dipole moment with weak binding energy. The polarity for the NPX loaded OH-B12N12 shows the feasibility of ameliorating the situation of solubility desirable for drug delivery systems in biological devices. Through the analysis of molecular docking, it was found that NPX loaded OH-B12N12 is potent inhibitors of TNF-α receptor and IL-1 receptor targets compared to B12N12 and B12P12 systems.

The Gibbs Energy–Potential Energy Conundrum and Chemical Reactivity: Implications for Catalysis and Enzyme Action

The interpretation of transition state theory via reaction energy profiles is problematical, as it remains unclear whether the energy being represented is the Gibbs energy or the potential energy. Although transition state theory is formally an extension of classical equilibrium theory, employing the Gibbs energy can lead to ambiguities in explaining reactivity trends and differences. Thus, the differential reactivity of the carbonyl group in carboxylic esters and carboxylic acid chlorides, when present in the same molecule, can only be explained by invoking transition state effects because of the common ground state. The said transition state effects, however, apparently need implausible assumptions.&#x0D; It is argued herein that these ambiguities can be avoided by employing potential energy. In particular, by invoking the “localized” potential energy at a reactive center, ground state effects can be brought into play. This is likely to be largely vibrational potential energy, as this is closely involved in bond breaking and making. It appears, therefore, that transition state theory is best viewed in a qualitative sense for it to be practically meaningful.&#x0D; These arguments, in fact, have intriguing implications for catalysis, particularly the theory of enzyme catalysis. Thus, enzymes apparently possess large negative Gibbs energies of formation, hence their reactivity cannot be explained by ground state effects. However, if the “localized” potential energy of the reactive groups in the active site is considered, the phenomenal reactivity of enzymes becomes comprehensible, in an alternative to the Pauling hypothesis of transition state stabilization. This generally implies that the action of catalysts needs to take into account the ground state potential energy of the catalyst, which is almost always ignored in current theoretical treatments.

Crunching Dilaton, Hidden Naturalness.

We introduce a new approach to the Higgs naturalness problem. The Higgs mixes with the dilaton of a conformal field theory (CFT) sector whose true ground state has a large negative vacuum energy. If the Higgs vacuum expectation value is nonzero and below O(TeV), the CFT admits a second metastable vacuum, where the expansion history of the Universe is conventional. As a result, only Hubble patches with unnaturally small values of the Higgs mass do not immediately crunch. The main experimental prediction of this mechanism is a dilaton in the 0.1-10GeV range that mixes with the Higgs and can be detected at future colliders and experiments searching for weakly coupled particles.

Reaction of Cu(II) Chelates with Uranyl Nitrate to Form a Coordination Complex or H-Bonded Adduct: Experimental Observations and Rationalization by Theoretical Calculations.

Four new heterometallic Cu(II)-U(VI) species, [{(CuL1)(CH3CN)}UO2(NO3)2] (1), [{(CuL2)(CH3CN)}UO2(NO3)2] (2), [{(CuL3)(H2O)}UO2(NO3)2] (3), and [UO2(NO3)2(H2O)2]·2[CuL4]·H2O (4), were synthesized using four different metalloligands ([CuL1], [CuL2], [CuL3], and [CuL4], respectively) derived from four unsymmetrically dicondensed N,O-donor Schiff bases. Single-crystal structural analyses revealed that complexes 1, 2, and 3 have a discrete dinuclear [Cu-UO2] core in which one metalloligand, [CuL], is connected to the uranyl moiety via a double phenoxido bridge. Two chelating nitrate ions complete the octa-coordination around uranium. Species 4 is a cocrystal, where a uranyl nitrate dihydrate is sandwiched between two metalloligands [CuL4] by the formation of strong hydrogen bonds between the H atoms of the coordinated water molecules to U(VI) and the O atoms of [CuL4]. Spectrophotometric titrations of these four metalloligands with uranyl nitrate dihydrate in acetonitrile showed a well-anchored isosbestic point between 300 and 500 nm in all cases, conforming with the coordination of [CuL1], [CuL2], [CuL3], and the H-bonding interaction of [CuL4] with UO2(NO3)2. This behavior of [CuL4] was utilized to selectively bind metal ions (e.g., Mg2+, Ca2+, Sr2+, Ba2+, and La3+) in the presence of UO2(NO3)2·2H2O in acetonitrile. The formation of these Cu(II)-U(VI) species in solution was also evaluated by steady-state fluorescence quenching experiments. The difference in the coordination behavior of these metalloligands toward [UO2(NO3)2(H2O)2] was studied by density functional theory calculations. The lower flexibility of the ethylenediamine ring and a large negative binding energy obtained from the evaluation of H bonds and supramolecular interactions between [CuL4] and [UO2(NO3)2(H2O)2] corroborate the formation of cocrystal 4. A very good linear correlation (r2 = 0.9949) was observed between the experimental U═O stretching frequencies and the strength of the equatorial bonds that connect the U atom to the metalloligand.

Leucoefdin a potential inhibitor against SARS CoV-2 Mpro

Leucoefdin an important constituent of various fruits such as banana, raspberry, etc. was explored to target MPro protease of SARS Co-V 2. Ligand was found to bind at active site of MPro with large negative binding energies in molecular docking and simulation study. The docking results showed that Leucoefdin interacted with the MPro by forming hydrogen bonds, at Leu 141, His163, His 164, and Glu 166. Other non-bonded interactions were seen at Met49, Pro52, Tyr54, Phe140, Leu141, Cys145 and Met165. Results of Leucoefdin was in coherence with the recently reported MPro protease-inhibitor complex. It even displayed better binding energies (kcal/mol) in HTVS (-6.28), SP (-7.28), XP (-9.29) and MMGBSA (-44.71) as compared to the reference ligand [HTVS (-4.87), SP (-6.79), XP (-5.75) and MMGBSA (-47.76)]. Leucoefdin-MPro complex on molecular dynamic simulation showed initial fluctuations in RMSD plot for a certain period and attained equilibrium which remained stable during entire simulation for 150 ns. RMSF of protein showed less secondary structure fluctuations and a greater number of H-bond formation with Leucoefdin during 150 ns simulation. Post simulation MMGBSA analysis showed binding energy of -45.98 Kcal/mol. These findings indicated the potential of Leucoefdin as lead compound in R&D for drug discovery and development against SARS CoV-2. Communicated by Ramaswamy H. Sarma

Electronic structures, magnetic properties, and martensitic transformation in all-d-metal Heusler-like alloys Cd2MnTM (TM = Fe, Ni, Cu)**Project supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ19E010006), the National Natural Science Foundation of China (Grant Nos. 51671048 and 91963123), the Ten Thousand Talents Plan of Zhejiang Province, China (Grant No. 2018R52003), and the Fundamental Research Funds for

The electronic structures, magnetic properties, and martensitic transformation in all-d-metal Heusler-like alloys Cd2MnTM (TM = Fe, Ni, Cu) were investigated by the first-principles calculations based on density-functional theory. The results indicate that all three alloys are stabilized in the ferromagnetic L21-type structure. The total magnetic moments mainly come from Mn and Fe atoms for Cd2MnFe, whereas, only from Mn atoms for Cd2MnNi and Cd2MnCu. The magnetic moment at equilibrium lattice constant of Cd2MnFe (6.36 μB) is obviously larger than that of Cd2MnNi (3.95 μB) and Cd2MnCu (3.82 μB). The large negative energy differences (ΔE) between martensite and austenite in Cd2MnFe and Cd2MnNi under tetragonal distortion and different uniform strains indicate the possible occurrence of ferromagnetic martensitic transformation (FMMT). The minimum total energies in martensitic phase are located with the c/a ratios of 1.41 and 1.33 for Cd2MnFe and Cd2MnNi, respectively. The total moments in martensitic state still maintain large values compared with those in cubic state. The study is useful to find the new all-d-metal Heusler alloys with FMMT.

Quantum molecular study of mesoporous silica nanoparticle as a delivery system for troxacitabine anticancer drug

Based on unique intrinsic properties of silica nanoparticles (SNPs) such as large pore size, large surface area, good biocompatibility and stable aqueous dispersion, the exterior surface of SNP for the covalent and noncovalent functionalization of troxacitabine (TCB) anticancer drug has been investigated via DFT calculations, AIM analysis, free energies of solvation and binding energies at B3LYP and M06-2X methods in both gas and liquid phases. Because of the large negative binding energies, it is predicted that sufficient drug loading will be achieved. The increase in drug solubility in this drug delivery system showed that SNP is an appropriate carrier for TCB drug delivery. The increased solubility and high binding energy are related to the formation of hydrogen bonds. The evaluation of the strength and characteristic of hydrogen bonds by AIM analysis demonstrated that several medium hydrogen bonds are formed between the drug and the carrier. The result of reaction between SNP and TCB may produce two products (SNP/TCB1–2) in which TCB approaches SNP through CH2OH and NH2 functional groups. The product of CH2OH pathway is more stable than that of NH2 pathway. These products may have some uses as prodrugs.

Specificity and affinity of multivalent ions adsorption to kaolinite surface

Understanding the specific adsorption mechanism(s) of multivalent ions onto clay mineral surfaces in a high salinity environment is theoretically and practically important in many areas including mineral separation and tailings disposals. This paper focuses on both qualitative and quantitative studies to describe the effect of multivalent-ion specificity on the kaolinite surface. The measured zeta potential of kaolinite particles treated with di- and trivalent chloride salts (up to 100 mM) was used to quantify the surface binding constant of metal ions to the kaolinite surface by the surface complexation model. The model results show that ion-pairing and hydration energy are two main factors that control the adsorption of di- and trivalent ions onto the kaolinite surface. The established affinity series of adsorption to kaolinite surface, Al3+ > Fe2+ > Fe3+ > Mg2+ > Ca2+, matches the hydration energy and calculated ion-pairing concentration. Further XPS analysis and molecular dynamics simulation revealed that Al3+ and Fe2+ could directly form inner-sphere complexes due to their high electronegativity and weak pairing ability with Cl− ion, while Mg2+ and Ca2+ ions adsorb onto the outer-sphere of kaolinite surface because of their strong pairing ability with Cl− ion and low electronegativity. However, higher electronegativity with large negative hydration energy leads to weaker affinity to kaolinite surface, as in the case of Fe3+. A linear relationship between surface binding constant and first hydrolysis constant of metal and kaolinite surface was also established. The outcomes of this work shed a new insight into the multivalent ion adsorption to kaolinite in controlling the selectivity and efficiency of mineral separation and dewatering processes.