Identification of Scutebarbatine B metabolites in rats using UHPLC-Q-Orbitrap-MS/MS and exploration of its mechanism of reversal multidrug resistance in breast cancer by network pharmacology and molecular docking studies.

Scutebarbatine B (SBT-B) is a neo-clerodane diterpenic compound isolated from Scutellaria barbata D. Don (S. barbata), which has been reported to exhibit inhibitory P-glycoprotein (P-gp) property in MCF-7/ADR cells.

Broadband and Spectrally Selective Photothermal Conversion through Nanocluster Assembly of Disordered Plasmonic Metasurfaces.

Plasmonic metasurfaces have been realized for efficient light absorption, thereby leading to photothermal conversion through nonradiative decay of plasmonic modes. However, current plasmonic metasurfaces suffer from inaccessible spectral ranges, costly and time-consuming nanolithographic top-down techniques for fabrication, and difficulty of scale-up. Here, we demonstrate a new type of disordered metasurface created by densely packing plasmonic nanoclusters of ultrasmall size on a planar optical cavity.

Two new indole alkaloids from and their evaluation for cytotoxic activities.

Two new indole alkaloids, naucleamide H () and (±)-19--butylangustoline (), along with seven known alkaloids, 3,14-dihydroangustine (), (-)-naucleofficine D (), (+)-naucleofficine D (), nauclefine (), angustidine (),19--ethylangustoline () and angustine () were isolated from the water extract of . The structures of these compounds were established by spectroscopic analysis. Among them, the cytotoxicity of , , and were evaluated against six human cancer cell lines (HepG-2, SKOV3, HeLa, SGC 7901, MCF-7 and KB) for the first time with 5-fluorouracil as a positive control drug.

Two new neolignans and an indole alkaloid from the stems of Nauclea officinalis and their biological activities.

A pair of new diastereoisomers neolignans (1-2) and a new alkaloid (7) were isolated from the stems of Nauclea officinalis: naucleaoxyneolignoside A (1), naucleaoxyneolignoside B (2), (2S,3S)-javaniside (7), together with nine known compounds, 2S-3,3-di-(4-hydroxy-3-methoxyphenyl)-propane-1,2-diol (3), threo-1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol (4), nauclefine (5), angustidine (6), naucleoxoside A (8), naucleoxoside B (9), angustoline (10), (3S,19S)-3,14-dihydroangustoline (11), and (3S,19R)-3,14-dihydroangustoline (12).The structures of 1, 2 and 7 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparison of their data with those reported in the literature. The absolution configurations of 1, 2, 7,11 and 12 were confirmed by the quantum chemical CD calculation method.

Metal Nanocluster-Metal Organic Framework-Polymer Hybrid Nanomaterials for Improved Hydrogen Detection.

The development of hydrogen sensors is of paramount importance for timely leak detection and remains a crucial unmet need. Palladium-based materials, well known as hydrogen sensors, still suffer from poisoning and deactivation. Here, a hybrid hydrogen sensor consisting of a Pd nanocluster (NC) film, a metal-organic framework (MOF), and a polymer, are proposed.

The rapid profiling and simultaneous determination of 12 major alkaloids in by UPLC-Q-TOF-MS and HPLC-ESI-MS/MS.

For the first time, we determined the phytochemical profile of alkaloids from using ultraperformance liquid chromatography-quadrupole-time-of-flight-tandem mass spectrometry (UPLC-Q-TOF-MS/MS). A rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry method was subsequently developed and fully validated for the simultaneous determination of 12 major alkaloid constituents in : pumiloside; naucleoxoside A; naucleoxoside B; nauclefine; angustidine; angustoline; (3,19)-3,14-dihydroangustoline ([]20D: (-)191°); (3,19)-3,14-dihydroangustoline ([]20D: (-)294.7°); strictosamide; angustine; vincosamide; and 3,14-dihydroangustine.

Simultaneous determination of 11 alkaloids in rat plasma by LC-ESI-MS/MS and a pharmacokinetic study after oral administration of total alkaloids extracted from Naucleaofficinalis.

Ethnopharmacological Relevance: Nauclea officinalis, a widely used Li medicine, has been used for the treatment of cold, fever, bronchitis, pneumonia, acute tonsillitis, and other ailments. Modern pharmacological studies have demonstrated that the most abundant and active components in N. officinalis are alkaloids, which possess various biological properties such as antibacterial and antitumor activities.

Plasmonic evolution of atomically size-selected Au clusters by electron energy loss spectrum.

The plasmonic response of gold clusters with atom number () = 100-70 000 was investigated using scanning transmission electron microscopy-electron energy loss spectroscopy. For decreasing , the bulk plasmon remains unchanged above = 887 but then disappears, while the surface plasmon firstly redshifts from 2.4 to 2.

A Gd@C single-molecule electret.

Electrets are dielectric materials that have a quasi-permanent dipole polarization. A single-molecule electret is a long-sought-after nanoscale component because it can lead to miniaturized non-volatile memory storage devices. The signature of a single-molecule electret is the switching between two electric dipole states by an external electric field.

Beam generation and structural optimization of size-selected Au clusters.

A size-selected beam of Au clusters is generated in a gas-phase condensation cluster source equipped with a lateral time-of-flight mass selector. The beam current reaches up to 9.13 nA for small clusters and 80 pA for Au clusters, which are then analyzed using a scanning transmission electron microscope.

A molecular device providing a remarkable spin filtering effect due to the central molecular stretch caused by lateral zigzag graphene nanoribbon electrodes.

Through the density functional theory, we studied molecular devices composed of single tetrathiafulvalene (TTF) molecules connected with zigzag graphene nanoribbon electrodes by four different junctions. Interestingly, some devices have exhibited half-metallic behavior and can bring out a perfect spin filtering effect and remarkable negative differential resistance behavior. The current-voltage characteristics show that these four devices possess different spin current values.

An ultrahigh resolution pressure sensor based on percolative metal nanoparticle arrays.

Tunneling conductance among nanoparticle arrays is extremely sensitive to the spacing of nanoparticles and might be applied to fabricate ultra-sensitive sensors. Such sensors are of paramount significance for various application, such as automotive systems and consumer electronics. Here, we represent a sensitive pressure sensor which is composed of a piezoresistive strain transducer fabricated from closely spaced nanoparticle films deposited on a flexible membrane.

Pd Nanoparticle Film on a Polymer Substrate for Transparent and Flexible Hydrogen Sensors.

Alongside the rise in fully automated equipment and wearable devices, there is currently a high demand for optically transparent and flexible gas sensors operating at room temperature. Nanoparticle films are ideal H-sensing materials that can be coupled with flexible substrates because of their discrete nanogranular structure and unique interparticle electrical responsiveness. In this work, we present an optically transparent and flexible H sensor based on a Pd nanoparticle film, prepared on a polyethylene terephthalate sheet using a straightforward nanocluster deposition technique.

Anomalous quantization trajectory and parity anomaly in Co cluster decorated BiSbTeSe nanodevices.

Dirac Fermions with different helicities exist on the top and bottom surfaces of topological insulators, offering a rare opportunity to break the degeneracy protected by the no-go theorem. Through the application of Co clusters, quantum Hall plateaus were modulated for the topological insulator BiSbTeSe, allowing an optimized surface transport. Here, using renormalization group flow diagrams, we show the extraction of two sets of converging points in the conductivity tensor space, revealing that the top surface exhibits an anomalous quantization trajectory, while the bottom surface retains the 1/2 quantization.

Structure and magnetic properties of icosahedral PdAg (x = 0-13) clusters.

In this article, we present a modified Velocity-Verlet algorithm that makes cluster system converge rapidly and accurately. By combining it with molecular dynamics simulations, we develop an effective global sampling method for extracting isomers of bimetallic clusters. Using this method, we obtain the isomers of icosahedral PdAg (x = 0-13).

Response Characteristics of Hydrogen Sensors Based on PMMA-Membrane-Coated Palladium Nanoparticle Films.

Coating a polymeric membrane for gas separation is a feasible approach to fabricate gas sensors with selectivity. In this study, poly(methyl methacrylate)-(PMMA-)membrane-coated palladium (Pd) nanoparticle (NP) films were fabricated for high-performance hydrogen (H) gas sensing by carrying out gas-phase cluster deposition and PMMA spin coating. No changes were induced by the PMMA spin coating in the electrical transport and H-sensing mechanisms of the Pd NP films.

Directed growth of graphene nanomesh in purified argon via chemical vapor deposition.

Graphene nanomeshes (GNMs), new graphene nanostructures with tunable bandgaps, are potential building blocks for future electronic or photonic devices, and energy storage and conversion materials. In previous works, GNMs have been successfully prepared on Cu foils by the H etching effect. In this paper, we investigated the effect of Ar on the preparation of GNMs, and how the mean density and shape of them vary with growth time.

Discovery of a new type of topological Weyl fermion semimetal state in MoWTe.

The recent discovery of a Weyl semimetal in TaAs offers the first Weyl fermion observed in nature and dramatically broadens the classification of topological phases. However, in TaAs it has proven challenging to study the rich transport phenomena arising from emergent Weyl fermions. The series MoWTe are inversion-breaking, layered, tunable semimetals already under study as a promising platform for new electronics and recently proposed to host Type II, or strongly Lorentz-violating, Weyl fermions.

Nonsequential double ionization with mid-infrared laser fields.

Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields.

Local Magnetoelectric Effect in La-Doped BiFeO3 Multiferroic Thin Films Revealed by Magnetic-Field-Assisted Scanning Probe Microscopy.

Multiferroic La-doped BiFeO3 thin films have been prepared by a sol-gel plus spin-coating process, and the local magnetoelectric coupling effect has been investigated by the magnetic-field-assisted scanning probe microscopy connected with a ferroelectric analyzer. The local ferroelectric polarization response to external magnetic fields is observed and a so-called optimized magnetic field of ~40 Oe is obtained, at which the ferroelectric polarization reaches the maximum. Moreover, we carry out the magnetic-field-dependent surface conductivity measurements and illustrate the origin of local magnetoresistance in the La-doped BiFeO3 thin films, which is closely related to the local ferroelectric polarization response to external magnetic fields.

Electric field control of the magnetic anisotropy energy of double-vacancy graphene decorated by iridium atoms.

To solve the fundamental dilemma in data storage applications, it is crucial to manipulate the magnetic anisotropy energy (MAE). Herein, using first-principles calculations, we predict that the system of double-vacancy graphene decorated by iridium atoms possesses high stability, giant MAE, perpendicular-anisotropy and long-range ferromagnetic coupling. More importantly, the amplitude of MAE can be manipulated by electric fields.

Polarization-dependent interfacial coupling modulation of ferroelectric photovoltaic effect in PZT-ZnO heterostructures.

Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit.

Weak antilocalization in Cd3As2 thin films.

Recently, it has been theoretically predicted that Cd3As2 is a three dimensional Dirac material, a new topological phase discovered after topological insulators, which exhibits a linear energy dispersion in the bulk with massless Dirac fermions. Here, we report on the low-temperature magnetoresistance measurements on a ~50 nm-thick Cd3As2 film. The weak antilocalization under perpendicular magnetic field is discussed based on the two-dimensional Hikami-Larkin-Nagaoka (HLN) theory.

High-temperature quantum anomalous Hall effect in honeycomb bilayer consisting of Au atoms and single-vacancy graphene.

The quantum anomalous Hall effect (QAHE) is predicted to be realized at high temperature in a honeycomb bilayer consisting of Au atoms and single-vacancy graphene (Au2-SVG) based on the first-principles calculations. We demonstrate that the ferromagnetic state in the Au2-SVG can be maintained up to 380 K. The combination of spatial inversion symmetry and the strong SOC introduced by the Au atoms causes a topologically nontrivial band gap as large as 36 meV and a QAHE state with Chern number C = -2.

Solvothermal Synthesis of Lateral Heterojunction Sb2Te3/Bi2Te3 Nanoplates.

A lateral heterojunction of topological insulator Sb2Te3/Bi2Te3 was successfully synthesized using a two-step solvothermal method. The two crystalline components were separated well by a sharp lattice-matched interface when the optimized procedure was used. Inspecting the heterojunction using high-resolution transmission electron microscopy showed that epitaxial growth occurred along the horizontal plane.