Metabolite identification of tanshinol borneol ester in rats by high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight mass spectrometry

Tanshinol borneol ester (DBZ) is a potential drug candidate composed of danshensu and borneol. It shows anti‐ischemic and anti‐atherosclerosis activity. However, little is known about its metabolism in vivo. This research aimed to elucidate the metabolic profile of DBZ through analyzing its metabolites using high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight mass spectrometry. Chromatographic separation was performed on an Agilent TC‐C₁₈ column (150 × 4.6 mm, 5.0 μm) with gradient elution using methanol and water containing 0.2% (v/v) formic acid as the mobile phase. Metabolite identification involved analyzing the retention behaviors, changes in molecular weights and MS/MS fragment patterns of DBZ and its metabolites. As a result, 20 potential metabolites were detected and tentatively identified in rat plasma, urine and feces after administration of DBZ. DBZ could be metabolized to O‐methylated DBZ, DBZ‐O‐glucuronide, O‐methylated DBZ‐O‐glucuronide, hydroxylated DBZ and danshensu. Danshensu, a hydrolysis product of DBZ, could further be transformed into 12 metabolites. The proposed method was confirmed to be a reliable and sensitive alternative for characterizing metabolic pathways of DBZ and providing valuable information on its druggability.     

Synthesis of novel fluorinated benzothiazol-2-yl-1,2,4-triazoles: Molecular docking,antifungal evaluation and in silico evaluation for SAR

Lead hybridization concept was used to design and synthesize twenty novel hybrid compounds by combining fungicidal leads viz. 6-flouro-1,3-benzothiazol-2-amine and 1,2,4-triazoles in a single molecule, with the aim of discovery of high potential novel fungicides. Antifungal evaluation of synthesized 6-flourobenzothiazol-2-yl-1,2,4-triazoles against various phytopathogenic fungi revealed synergistic effect of combination of leads with one another in all the test compounds. Some of the synthesized compounds showed excellent fungitoxicity comparable with the standard fungicides used. In silico toxicity of all the compounds was equivalent to the standard fungicides used. Docking studies and Lipinski filtration were performed in order to present the rationale of structure activity relation. Compounds 2, 8, 15 and 18 were screened to act as leads for further modification and use.     

Suppression of Chaos and Phase Locking in Two Coupled Nonidentical Neurons under Periodic Input

Dynamical behaviour of two coupled neurons with at least one of them being chaotic is presented. Bifurcation diagrams and Lyapunov exponents are calculated to diagnose the dynamical behaviour of the coupled neurons with the increasing coupling strength. It is found that when the coupling strength increases, a chaotic neuron can be controlled by the coupling between neurons. At the same time, phase locking is studied by the maxima of the differences of instantaneous phases and average frequencies between two coupled neurons, and the inherent connection of phase locking and the suppression of chaos is formulated. It is observed that the onset of phase locking is closely related to the suppression of chaos. Finally, a way for suppression of chaos in two coupled nonidentical neurons under periodic input is suggested.     

Dolbeault cohomology groups of compact pseudo-Kähler homogeneous manifolds

It is well known that a pseudo-Kähler structure is one of the natural generalizations of a Kähler structure. In this paper, we consider the Dolbeault cohomology groups of compact pseudo-Kähler homogeneous manifolds.     

Robust stability for uncertain stochastic fuzzy BAM neural networks with time-varying delays

In this Letter, by utilizing the Lyapunov functional and combining with the linear matrix inequality (LMI) approach, we analyze the global asymptotic stability of uncertain stochastic fuzzy Bidirectional Associative Memory (BAM) neural networks with time-varying delays which are represented by the Takagi-Sugeno (TS) fuzzy models. A new class of uncertain stochastic fuzzy BAM neural networks with time varying delays has been studied and sufficient conditions have been derived to obtain conservative result in stochastic settings. The developed results are more general than those reported in the earlier literatures. In addition, the numerical examples are provided to illustrate the applicability of the result using LMI toolbox in MATLAB.     

Transport of waves in disordered waveguides: A potential model

We study the statistical properties of wave transport in a disordered waveguide. We first derive the properties of a “building block” (BB) of length δL starting from a potential model consisting of thin potential slices. We then find a diffusion equation—in the space of transfer matrices that describe our system—which governs the evolution with the length L of the disordered waveguide of the transport properties of interest. The latter depend only on the mean free paths and on no other property of the slice distribution. The universality that arises demonstrates the existence of a generalized central-limit theorem. We have developed a numerical simulation in which the universal statistical properties of the BB found analytically are first implemented numerically, and then the various BBs are combined to construct the full waveguide. The reported results thus obtained are in good agreement with microscopic calculations, for both bulk and surface disorder.     

Theoretical analysis of trends in hydrogen bonding involving halogen acceptors (F−At) covalently bonded to a group 14 atom (C−Pb)

In this work, extensive quantum-chemical calculations have been carried out to identify and elucidate trends in the hydrogen-bonding (HB) interaction involving halogen acceptors covalently bonded to a group 14 atom. A series of 25 heterodimers composed of MH₃X (where M = C?Pb and X = F?At) and HNC molecules have been selected as model complexes stabilised by the HB interaction occurring between the X atom of MH₃X and the H atom of HNC. The interaction energy (E_int) between MH₃X and HNC in the MH₃X···HNC complexes falls in the range from ?2.7 to ?10.8 kcal/mol, indicating weak or medium strength of HB in these complexes. The strength of HB in the complexes remains consistent with the well-known HB weakening as X gets heavier. Regarding the effect of M on E_int, the gradual strengthening of HB is observed while descending group 14, but only from M = Si to M = Pb. The trends in E_int are compared with various HB-related parameters obtained from vibrational analysis, the natural bond orbital (NBO) method, the symmetry-adapted perturbation theory (SAPT) and the quantum theory of atoms in molecules (QTAIM). The parameters that present clear (possibly linear) relationships with E_int have been selected to characterise the effect of M and X on the HB interaction.     

New Double Wronskian Solutions of the Whitham-Broer-Kaup System: Asymptotic Analysis and Resonant Soliton Interactions

In this paper, by the Darboux transformation together with the Wronskian technique, we construct new double Wronskian solutions for the Whitham-Broer-Kaup (WBK) system. Some new determinant identities are developed in the verification of the solutions. Based on analyzing the asymptotic behavior of new double Wronskian functions as t → ±∞, we make a complete characterization of asymptotic solitons for the non-singular, non-trivial and irreducible soliton solutions. It turns out that the solutions are the linear superposition of two fully-resonant multi-soliton configurations, in each of which the amplitudes, velocities and numbers of asymptotic solitons are in general not equal as t → ±∞. To illustrate, we present the figures for several examples of soliton interactions occurring in the WBK system.     

Ultrafast Saturable Absorption of Core/Shell Colloidal Quantum Dots

Ultrafast saturable absorption (SA) materials that are capable of blocking the optical absorption under strong excitation have extensive applications in photonic devices. This work presents core/shell colloidal quantum dots (CQDs) which have the quantized energy levels, excellent band gap tunability, and possess significant SA performance. When the band gap is close to the pump pulse energy, the CQDs show significant resonant SA response. At the same excitation conditions, the core/shell CQDs dispersions show better SA response than graphene dispersions, and comparable to the recently reported molybdenum disulfide. The carrier dynamics of the SA of the CQDs is analyzed systematically. The research has also found that the two‐photon absorption of the CQDs show nearly cubic power law of the band gap, while the SA performance keeps almost the same in the nonresonant regime. Further, superior passive Q‐switched laser behavior is observed using the CQDs as a saturable absorber. The results directly reveal the physical processes of this basic problem and broaden the applications of CQDs in photonic devices.