Boosting responses of fluorescent imaging probes toward sulfur dioxide through engineering side chain length.

Development of fluorescent probes with high sensitivity and specificity is always desirable, yet, challenging. Conventionally, improving the responses of probes relied on optimizing the reactivities of recognition sites, either by increasing the binding affinity or reaction rates. Herein, we found the sensitivity and response kinetics could be improved by changing the aggregation behaviors of probes.

Manipulating π-π Interactions between Single Molecules by Using Antenna Electrodes as Optical Tweezers.

Via conductance measurements of thousands of single-molecule junctions, we report that the π-π coupling between neighboring aromatic molecules can be manipulated by laser illumination. We reveal that this optical manipulation originates from the optical plasmonic gradient force generated inside the nanogaps, in which the gapped antenna electrodes act as optical tweezers pushing the neighboring molecules closer together. These findings offer a nondestructive approach to regulate the interaction of the molecules, deepening the understanding of the mechanism of π-π interaction, and open an avenue to manipulate the relative position of extremely small objects down to the scale of single molecules.

Simulating temperature and tautomeric effects for vibrationally resolved XPS of biomolecules: Combining time-dependent and time-independent approaches to fingerprint carbonyl groups.

Carbonyl groups (C=O) play crucial roles in the photophysics and photochemistry of biological systems. O1s x-ray photoelectron spectroscopy allows for targeted investigation of the C=O group, and the coupling between C=O vibration and O1s ionization is reflected in the fine structures. To elucidate its characteristic vibronic features, systematic Franck-Condon simulations were conducted for six common biomolecules, including three purines (xanthine, caffeine, and hypoxanthine) and three pyrimidines (thymine, 5F-uracil, and uracil).

Regulation of π-π interactions between single aromatic molecules by bias voltage.

π-stacking interaction, as a fundamental type of intermolecular interaction, plays a crucial role in generating new functional molecules, altering the optoelectronic properties of materials, and maintaining protein structural stability. However, regulating intermolecular π-π interactions at the single-molecule level without altering the molecular conformation as well as the chemical properties remains a significant challenge. To this end, conductance measurement with thousands of single molecular junctions employing a series of aromatic molecules, we demonstrate that the π-π coupling between neighboring aromatic molecules with rigid structures in a circuit can be greatly enhanced by increasing the bias voltage.

Theoretical and computational methods for tip- and surface-enhanced Raman scattering.

Raman spectroscopy is a versatile tool for acquiring molecular structure information. The incorporation of plasmonic fields has significantly enhanced the sensitivity and resolution of surface-enhanced Raman scattering (SERS) and tip-enhanced Raman spectroscopy (TERS). The strong spatial confinement effect of plasmonic fields has challenged the conventional Raman theory, in which a plane wave approximation for the light has been adopted.

Effect of Liver Segments and Hepatic Fibrosis Grade on Repeatability, Reliability, and Diagnostic Efficiency of Intravoxel Incoherent Motion.

Background: Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) is considered a potential marker of hepatic fibrosis (HF).

Objective: To explore the influencing factors of repeatability and reliability in IVIM-DWI parameters of ROI-based liver segments in participants with HF and healthy volunteers (HV) and to assess the diagnostic efficiency of these parameters in HF.

Methods: Participants with early HF (EHF, n=59) or advanced HF (AHF, n=38) and HV (n=48) were recruited.

First-principles studies on the structural, electronic, and optical properties of 2D transition metal dichalcogenide (TMDC) and Janus TMDCs heterobilayers.

Van der Waals heterobilayers formed by vertically stacked two-dimensional materials could be a viable candidate for optoelectronics. This study carried out first-principles calculations to study the geometrical, electronic and optical properties of heterobilayers consisting transition metal dichalcogenide (TMDC) SnSeand Janus TMDCs ZrSSe and SnSSe. Eight possible configurations SeSnSe-SSnSe (I), SeSnSe-SeSnS (II), SeSnSe-SZrSe (III), SeSnSe-SeZrS (IV), SSnSe-SZrSe (V), SSnSe-SeZrS (VI), SeSnS-SZrSe (VII) and SeSnS-SeZrS (VIII) are dynamically, thermally, energetically and mechanical stable.

Adsorption properties of a paracyclophane molecule on NaCl/Au surfaces: a first-principles study.

Ultrathin insulating layers are commonly applied in scanning tunneling microscope (STM) measurements on molecular systems to preserve the intrinsic properties of a sample. We examine in the present work the adsorption properties of a double-decker 3,3-paracyclophane (PCP) molecule supported on Au surfaces with thin NaCl monolayers (MLs) as the decoupling spacer by using first-principles calculations. The interactions between the adsorbed molecule and the substrate were analyzed in terms of the adsorption energy, dispersion interactions, charge transfer, and molecular structure changes.

A General Framework of Scanning Tunneling Microscopy Based on Bardeen's Approximation for Isolated Molecules.

Scanning tunneling microscopy (STM) is one of the most popular techniques for precise characterization. Yet, its current theoretical implementation is often based on the periodic boundary condition with the Tersoff-Hamann approximation, which is inefficient to explore the tip states other than the -wave and to treat properly the charged molecules that are ubiquitous in chemistry. In this work, we establish a general theoretical framework for STM image simulations, which is based on the Bardeen's approximation and utilizes the boundary condition of the cluster model.

Exploiting the Momentum Distribution in Atomically Confined Plasmonic Fields by Inelastic Scatterings.

The utilization of atomically confined plasmonic fields has revolutionized the imaging technique. According to the fundamental position-momentum uncertainty principle, such a narrow spatial distribution certainly leads to a broad momentum distribution in the fields, which has however been overlooked. Here we propose a novel exploitation for the momentum distribution by adaptively satisfying the conservation law of momentum in inelastic Raman scatterings in periodic systems, providing a unique optical means of directly measuring the whole phonon dispersions.

Gastroprotective mechanism of modified lvdou gancao decoction on ethanol-induced gastric lesions in mice: Involvement of Nrf-2/HO-1/NF-κB signaling pathway.

Modified Lvdou Gancao decoction (MLG), a traditional Chinese medicine formula, has been put into clinical use to treat the diseases of the digestive system for a long run, showing great faculty in gastric protection and anti-inflammatory, whereas its protective mechanisms have not been determined. The current study puts the focus on the protective effect and its possible mechanisms of MLG on ethanol-induced gastric lesions in mice. In addition to various gastric lesion parameters and histopathology analysis, the activities of a list of relevant indicators in gastric mucosa were explored including ALDH, ADH, MDA, T-SOD, GSH-Px, and MPO, and the mechanisms were clarified using RT-qPCR, ELISA Western Blot and immunofluorescence staining.

Vibrationally-Resolved X-ray Photoelectron Spectra of Six Polycyclic Aromatic Hydrocarbons from First-Principles Simulations.

Vibrationally resolved C 1s X-ray photoelectron spectra (XPS) of a series of six polycyclic aromatic hydrocarbons (PAHs; phenanthrene, coronene, naphthalene, anthracene, tetracene, and pentacene) were computed by combining the full core hole density functional theory and the Franck-Condon simulations with the inclusion of the Duschinsky rotation effect. Simulated spectra of phenanthrene, coronene, and naphthalene agree well with experiments both in core binding energies (BEs) and profiles, which validate the accuracy of our predictions for the rest molecules with no high-resolution experiments. We found that three types of carbons (inner C), (peripheral C bonded to three C atoms), and (peripheral C bonded to an H atom) show decreasing BEs.

Efficacy and safety of AnluoHuaxian pills on chronic hepatitis B with normal or minimally elevated alanine transaminase and early liver fibrosis: A randomized controlled trial.

Ethnopharmacological Relevance: The AnluoHuaxian pill (AHP) is a widely used patented medicine for chronic hepatitis B (CHB) patients with advanced fibrosis or cirrhosis that has been used in China for more than 15 years. However, data are lacking on whether monotherapy with AHP can be effective in CHB patients with alanine aminotransferase (ALT) levels less than 2 times the upper limit of normal (ALT<2ULN) and early liver fibrosis (F ≤ 2).

Aim Of The Study: We aimed to investigate whether monotherapy with AHP improves liver histology in these patients.

Optical Images of Molecular Vibronic Couplings from Tip-Enhanced Fluorescence Excitation Spectroscopy.

Tip-based photoemission spectroscopic techniques have now achieved subnanometer resolution that allows visualization of the chemical structure and even the ground-state vibrational modes of a single molecule. However, the ability to visualize the interplay between electronic and nuclear motions of excited states, i.e.

Ultrafast stimulated resonance Raman signatures of lithium polysulfides for shuttling effect characterization: An ab initio study.

The shuttling effect is a crucial obstacle to the practical deployment of lithium sulfur batteries (LSBs). This can be ascribed to the generation of lithium polysulfide (LiPS) redox intermediates that are soluble in the electrolyte. The detailed mechanism of the shuttling, including the chemical structures responsible for the loss of effective mass and the dynamics/kinetics of the redox reactions, are not clear so far.

Electric Field Controlled Single-Molecule Optical Switch by Through-Space Charge Transfer State.

Controlling the photon emission property of a single molecule is an important goal for nano-optics. We propose here a new mechanism for a single-molecule optical switch that utilizes the electric field (EF) in biased metallic nanojunctions to control photon emission of molecules with through-space charge transfer (TSCT) excited states. The EF-induced Stark effect is capable of flipping the order of the bright noncharge transfer state and dark TSCT state, resulting in the anticipated switching behavior.

Combined experimental and theoretical study on photoionization cross sections of benzonitrile and o/m/p-cyanotoluene.

Photoionization cross sections (PICSs) for the products of the reaction from CN with toluene, including benzonitrile and o/m/p-cyanotoluene, were obtained at photon energies ranging from ionization thresholds to 14 eV by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Theoretical calculations based on the frozen-core Hartree-Fock approximation and Franck-Condon simulations were carried out to cross-verify the measured PICS. The results show that the photoionization cross sections of benzonitrile and cyanotoluene isomers are similar.

Harvesting of surface plasmon polaritons: Role of the confinement factor.

Surface plasmon polaritons (SPPs) are propagating waves generated at the interface of a metal (metamaterial) and a dielectric. The intensity of SPPs often exponentially decays away from the surface, while their wavelengths can be tuned by the confinement effect. We present here a computational method based on quantum-mechanical theory to fully describe the interaction between confined SPPs and adsorbed molecules at the interface.

Theoretical assessment of vibrationally resolved C1s X-ray photoelectron spectra of simple cyclic molecules.

An interface between our in-house DynaVib package and quantum chemistry software Gamess-US is implemented for computing vibrationally-resolved K-edge X-ray photoelectron spectra (XPS) of molecules at the density functional theory level with both the full (FCH) and equivalent (ECH, or Z+1) core-hole approximations. To assess the influence of theoretical parameters (core-hole methods, vibronic coupling models, and basis sets), vibrationally-resolved C1s XPS of six simple cyclic molecules [furan, pyrrole, thiophene; benzene (C6H6 and C6D6); pyridine] were evaluated in the gas phase by both core-hole methods in combination with two time-independent vibronic coupling models, the Duschinsky rotation (DR) method and the linear coupling model (LCM). We achieved excellent/acceptable performance for FCH/Z+1 simulations in comparison with experiments.

Estimation for Runway Friction Coefficient Based on Multi-Sensor Information Fusion and Model Correlation.

Friction is a crucial factor affecting air accident occurrence on landing or taking off. Tire-runway friction directly contributes to aircraft stability on land. Therefore, an accurate friction estimation is a rising issue for all stakeholders.

Effects of Plasmon Modes on Resonant Raman Images of a Single Molecule.

Localized surface plasmons (LSPs) are excellent light sources at the nanoscale. How to precisely describe the interaction between LSPs and molecules has become an important issue. We present here a comprehensive study on the dependence of resonant Raman images on LSP modes generated by two typical nanostructures.

A Versatile Strategy for Surface Functionalization of Hydrophobic Nanoparticle by Boronic Acid Modified Polymerizable Diacetylene Derivatives.

The flourishing advancements in nanotechnology significantly boost their application in biomedical fields. Whereas, inorganic nanomaterials are normally prepared and capped with hydrophobic ligands, which require essential surface modification to increase their biocompatibility and endow extra functions. Phenylboronic acid derivatives have long been known for its capacity for selective recognition of saccharides.