We investigate the propagation and interaction dynamics of the optical dark bound solitons for the defocusing Lakshmanan-Porsezian-Daniel equation, which is a physically relevant generalization of ...the nonlinear Schrödinger equation involving the higher-order effects. Explicit N-dark soliton solutions in the compact determinant form are constructed via the binary Darboux transformation method. Bound states of the dark solitons are discussed when the incoherent solitons have the same velocity. We find an interesting phenomenon that dark soliton molecules and double-valley dark solitons (DVDSs) can be obtained by controlling the interval of the bound state dark solitons, and abundant interaction modalities between them can be formed. Moreover, dark soliton molecules always undergo elastic interactions with other solitons, while interactions for the DVDSs are usually inelastic, and special parameter conditions for elastic interaction of DVDSs through asymptotic analysis are obtained. Numerical simulations are employed to verify the stability of the bound state dark solitons. Analytical results obtained in this paper are expected to be useful for the experimental realization of bound-state dark solitons in optical fibers with higher-order effects and a further understanding of their optical transmission properties..
Ferulic acid (FA) has potential therapeutic effects in multiple diseases including cardiovascular diseases. However, the effect and molecular basis of FA in heart failure (HF) has not been thoroughly ...elucidated. Herein, we investigated the roles and mechanisms of FA in HF in isoproterenol (ISO)-induced HF rat model. Results found that FA ameliorated cardiac dysfunction, alleviated oxidative stress, reduced cell/myocardium injury-related enzyme plasma level, inhibited cardiocyte apoptosis in ISO-induced HF rat models. Moreover, FA reduced the co-localization of Keap1 and nuclear factor-E2-related factor 2 (Nrf2) in heart tissues of ISO-induced HF rats, and FA alleviated the inhibitory effects of ISO on expressions of p-Nrf2, heme oxygenase-1 (HO-1) and reduced nicotinamide adenine dinucleotide phosphate quinone dehydrogenase 1 (NQO1). Additionally, Nrf2 signaling pathway inhibitor ML385 showed adverse effects. FA weakened the effects of ML385 in ISO-induced HF rat models. Collectively, FA ameliorated HF by decreasing oxidative stress and inhibiting cardiocyte apoptosis via activating Nrf2 pathway in ISO-induced HF rats. Our data elucidated the underling molecular mechanism and provided a novel insight into the cardioprotective function of FA, thus suggested the therapeutic potential of FA in HF treatment.
An intriguing structural transition from the quasi‐planar form of B12 cluster upon the interaction with lithium atoms is reported. High‐level computations show that the lowest energy structures of ...LiB12, Li2B12, and Li3B12 have quasi‐planar (Cs), tubular (D6d), and cage‐like (Cs) geometries, respectively. The energetic cost of distorting the B12 quasi‐planar fragment is overcompensated by an enhanced electrostatic interaction between the Li cations and the tubular or cage‐like B12 fragments, which is the main reason of such drastic structural changes, resulting in the smallest tubular (Li2B12) and cage‐like (Li3B12) boron structures reported to date.
Let's play with a charge transfer tool! The energetic cost of distorting the B12 quasi‐planar fragment in Li2B12 and Li3B12 is overcompensated by an enhanced electrostatic interaction between the Li cations and the tubular or cage‐like B12 fragments. This is the main reason of a drastic structural changes in the B12 core, resulting in the smallest reported tubular (Li2B12) and cage‐like (Li3B12) boron structures.
Quantum chemical calculations using ab initio methods at the MRCI+Q(8,9)/def2‐QZVPPD and CCSD(T)/def2‐QZVPPD levels as well as using density functional theory are reported for the diatomic molecules ...AeN− (Ae=Ca, Sr, Ba). The anions CaN− and SrN− have electronic triplet (3Π) ground states with nearly identical bond dissociation energies De ~57 kcal/mol calculated at the MRCI+Q(8,9)/def2‐QZVPPD level. In contrast, the heavier homologue BaN− has a singlet (1Σ+) ground state, which is only 1.1 kcal/mol below the triplet (3Σ−) state. The computed bond dissociation energy of (1Σ+) BaN− is 68.4 kcal/mol. The calculations at the CCSD(T)‐full/def2‐QZVPPD and BP86‐D3(BJ)/def2‐QZVPPD levels are in reasonable agreement with the MRCI+Q(8,9)/def2‐QZVPPD data, except for the singlet (1Σ+) state, which has a large multireference character. The calculated atomic partial charges given by the CM5, Voronoi and Hirshfeld methods suggest small to medium‐sized Ae←N− charge donation for most electronic states. In contrast, the NBO method predicts for all species medium to large Ae→N− electronic charge donation, which is due to the neglect of the (n)p AOs of Ae atoms as genuine valence orbitals. Neither the bond orders nor the bond lengths correlate with the bond dissociation energies. The EDA−NOCV calculations show that the heavier alkaline earth atoms Ca, Sr, Ba use their (n)s and (n‐1)d orbitals for covalent bonding.
The dative bond in the 10 valence‐electron species AeN− has a multireference character with high bond multiplicity in the triplet (3Π) ground state of CaN− and SrN− and singlet (1Σ+) ground state of BaN−.
Quantum chemical calculations of the anions AeF− (Ae=Be−Ba) have been carried out using ab initio methods at the CCSD(T)/def2‐TZVPP level and density functional theory employing BP86 with various ...basis sets. The detailed bonding analyses using different charge‐ and energy partitioning methods show that the molecules possess three distinctively different dative bonds in the lighter species with Ae=Be, Mg and four dative bonds when Ae=Ca, Sr, Ba. The occupied 2p atomic orbitals (AOs) and to a lesser degree the occupied 2s AO of F− donate electronic charge into the vacant spx(σ) and p(π) orbitals of Be and Mg which leads to a triple bond Ae
F−. The heavier Ae atoms Ca, Sr, Ba use their vacant (n‐1)d AOs as acceptor orbitals which enables them to form a second σ donor bond with F− that leads to quadruply bonded Ae
F− (Ae=Ca−Ba). The presentation of molecular orbitals or charge distribution using only one isodensity value may give misleading information about the overall nature of the orbital or charge distribution. Better insights are given by contour line diagrams. The ELF calculations provide monosynaptic and disynaptic basins of AeF− which nicely agree with the analysis of the occupied molecular orbitals and with the charge density difference maps. A particular feature of the covalent bonds in AeF− concerns the inductive interaction of F− with the soft valence electrons in the (n)s valence orbitals of Ae. The polarization of the (n)s2 electrons induces a (n)spx hybridized lone‐pair orbital at atom Ae, which yields a large dipole moment with the negative end at Ae. The concomitant formation of a vacant (n)spx AO of atom Ae, which overlaps with the occupied 2p(σ) AO of F−, leads to a strong covalent σ bond.
A careful bonding analysis of the anions AeF‐ shows that the fluorine anion F− is a very strong donor via charge‐induced covalent interactions with alkaline earth atoms Ae, exhibiting triple bonds for Ae=Be, Mg and even quadruple bonds for the heavier atoms Ae=Ca, Sr, Ba due to their empty (n‐1)d valence orbitals. The unusual dipole moments with the negative end at the Ae atom are decomposed into pairwise electron contributions that reveal the special role of the HOMO.
A new class of beryllium‐boron clusters, beryllo‐borospherene, is described herein theoretically. When beryllium is gradually added to the B12 motif, it undergoes drastic structural modifications. ...The global minimum of the Be4B12+ cluster is an Archimedean beryllo‐borospherene in a 2A1 electronic ground state, composed of four boron triangles linked at each corner, resulting in a truncated tetrahedron with four B6 rings capped with four beryllium atoms. Beryllium forms strong bonding with the boron clusters through strong electrostatic and covalent interactions. For instance, the bonding between a beryllium atom and Be3B12 unit is best described as a Be+ fragment in a 2P excited state forming a strong and polarized electron‐sharing bond with Be3B12, followed by several dative interactions by employing its vacant s, p, and very high‐lying d orbitals. Counterintuitively, for an s‐block element, the p orbitals of beryllium are the most crucial atomic orbitals for bonding rather than s orbitals.
A new class of beryllium‐boron clusters, beryllo‐borospherene, is described herein theoretically. The most stable isomer of Be4B12+ cluster is a closed Archimedean beryllo‐borospherene, composed of four boron triangles linked at each corner, resulting in a truncated tetrahedron with four B6 rings capped with four beryllium atoms.
Pancake π-stacking produces shorter contacts than van der Waals bonding but it has strongly preferred configurations. By high-level multireference average quadratic coupled cluster theory for the ...singlet and triplet, we identify the specific orbital component and the nonspecific vdW contributions in the prototypical pancake-bonded dimer of phenalenyl thereby explaining the configurational preferences.
Planar boron clusters have often been regarded as “π‐analogous” to aromatic arenes because of their similar delocalized π‐bonding. However, unlike arenes such as C5H5− and C6H6, boron clusters have ...not previously shown the ability to form sandwich complexes. In this study, we present the first sandwich complex involving beryllium and boron, B7Be6B7. The global minimum of this combination adopts a unique architecture having a D6h geometry, featuring an unprecedented monocyclic Be6 ring sandwiched between two quasi‐planar B7 motifs. The thermochemical and kinetic stability of B7Be6B7 can be attributed to strong electrostatic and covalent interactions between the fragments. Chemical bonding analysis shows that B7Be6B7 can be considered as a B73−Be66+B73− complex. Moreover, there is a significant electron delocalization within this cluster, supported by the local diatropic contributions of the B7 and Be6 fragments.
We report the discovery of a previously unknown sandwich‐type complex consisting of beryllium and boron, which exhibits remarkable thermochemical and kinetical stability and displays aromatic characteristics. Through chemical bonding analysis, we show that B7Be6B7 can be conceptualized as a B73−Be66+B73− complex.
The Coronavirus disease 2019 (COVID‐19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) remains a global threat, exacerbated by the emergence of viral variants. ...Two variants of SARS‐CoV‐2, Omicron BA.2.75 and BA.5, led to global infection peaks between May 2022 and May 2023, yet their precise characteristics in pathogenesis are not well understood. In this study, we compared these two Omicron sublineages with the previously dominant Delta variant using a human angiotensin‐converting enzyme 2 knock‐in mouse model. As expected, Delta exhibited higher viral replication in the lung and brain than both Omicron sublineages which induced less severe lung damage and immune activation. In contrast, the Omicron variants especially BA.5.2 showed a propensity for cellular proliferation and developmental pathways. Both Delta and BA.5.2 variants, but not BA.2.75, led to decreased pulmonary lymphocytes, indicating differential adaptive immune response. Neuroinvasiveness was shared with all strains, accompanied by vascular abnormalities, synaptic injury, and loss of astrocytes. However, Immunostaining assays and transcriptomic analysis showed that BA.5.2 displayed stronger immune suppression and neurodegeneration, while BA.2.75 exhibited more similar characteristics to Delta in the cortex. Such differentially infectious features could be partially attributed to the weakened interaction between Omicron Spike protein and host proteomes decoded via co‐immunoprecipitation followed by mass spectrometry in neuronal cells. Our present study supports attenuated replication and pathogenicity of Omicron variants but also highlights their newly infectious characteristics in the lung and brain, especially with BA.5.2 demonstrating enhanced immune evasion and neural damage that could exacerbate neurological sequelae.
The bonding situation in the tricoordinated beryllium phenyl complexes BePh3−, (pyridine)BePh2 and (trimethylsilyl‐N‐heterocyclic imine)BePh2 is investigated experimentally and computationally. ...Comparison of the NMR spectroscopic properties of these complexes and of their structural parameters, which were determined by single crystal X‐ray diffraction experiments, indicates the presence of π‐interactions. Topology analysis of the electron density reveals elliptical electron density distributions at the bond critical points and the double bond character of the beryllium‐element bonds is verified by energy decomposition analysis with the combination of natural orbital for chemical valence. The present beryllium‐element bonds are highly polarized and the ligands around the central atom have a strong influence on the degree of π‐delocalization. These results are compared to related triarylboranes.
The bonding situation in tricoordinated beryllium phenyl complexes was evaluated. In all compounds π‐delocalisation was present in all compounds even though the beryllium‐element bonds are highly polarized. This delocalisation accounts for the rather small contribution of π‐interactions to the overall orbital energies of these compounds.
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