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Simple model of the ground state and spin-orbital excitations of free and adsorbed Fe(II) phthalocyanine molecules
摘要： We investigate the ground state and low-energy spin-orbital excitations of a single iron(II) phthalocyanine molecule in isolation and on an oxidized Cu(110) surface. Considering the subspace spanned by the three lowest spin-triplet states of 3A2g and 3Eg symmetry, we diagonalize the Hamiltonian made of the anisotropic spin-orbit interaction and the ligand ?eld splitting (cid:2), de?ned as the energy difference between 3Eg and 3A2g. We ?nd that the ground state switches from a 3Eg-like state with large orbital moment and out-of-plane easy axis for (cid:2) < ?60 meV to a 3A2g-like singlet state with in-plane easy axis for (cid:2) > ?60 meV. The analysis of the ?rst excited states in the two regimes explains the zero-?eld splitting data reported for β-FePc as well as for FePc molecules adsorbed on an oxidized Cu(110) surface [N. Tsukahara et al., Phys. Rev. Lett. 102, 167203 (2009)]. Importantly, the calculated magnetic susceptibility obtained with the ab initio value (cid:2) = 93 meV compares remarkably well with the experimental data of β-FePc in the whole available temperature range of 1–300 K.
关键词： spin-orbital excitations,anisotropic spin-orbit interaction,oxidized Cu(110) surface,Fe(II) phthalocyanine,ligand ?eld splitting
更新于2025-09-10 09:29:36
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Detection of soluble expression and in vivo interactions of the inner membrane protein OppC using green fluorescent protein
摘要： In this study, the in vivo interaction system of oligopeptide permease (Opp) proteins was analyzed, and a high expression system of inner membrane protein OppC was constructed by flexible usage of the green fluorescent protein (GFP). The Escherichia coli OppC gene, which encodes a transmembrane component of oligopeptide transporter, was cloned into different vectors. Recombinant plasmids were transformed into different E. coli strains, and the expression conditions were optimized. The effect of plasmids and expression strains on OppC production was evaluated by in-gel and western blot analyses. OppC produced by the pWaldo-GFPe vector, harboring the GFP reporter gene, transformed into E. coli C43(DE3) provided sufficient functional protein for biochemical and biophysical studies. In vivo protein-protein interactions were detected among oligopeptide permease proteins using a GFP fragment reassembly protocol. The substrate binding protein OppA showed no interaction with the other components, while the ATP-binding component OppD did not interact with OppF. OppD and OppF interacted with the transmembrane components OppB and OppC. OppB also showed direct interaction with OppC. In vivo OppC functionality was determined by constructing an OppC gene deletion strain. OppC was shown to be essential for peptide uptake, and non-essential for cell viability. These results could help in elucidating the oligopeptide transport mechanism in bacteria.
关键词： Oligopeptide permease,Protein-protein interaction,Inner membrane protein,Green fluorescent protein
更新于2025-09-10 09:29:36
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Mesoporous titania-coated biosensor and FEM model design for highly sensitive detection of low molecular weight targets
摘要： This paper presents the interest of a highly sensitive biosensor coated with a TiO2 mesoporous film as sensitive layer. The main novelty is related to the modelling of the device and simulation by using Finite Element Method with COMSOL Multiphysics software, as a good way to take into account the physical properties of porous 3D-layers. The strategy of using such Love wave devices, with 3D porous layers, offering further easy functionalization, aims not only to increase the amount of targets caught on the sensor surface, but also to enhance the detection mechanism by a higher perturbation of the Love wave acoustic energy which could be trapped inside the 3D sensitive layer. First, as a proof of concept, experimental devices with a 3D titania mesoporous layer were realized, and they have shown a good agreement with simulated results. Furthermore, experimental test with several Newtonian liquids are investigated, in a range of viscosities from 1 to 7 cP, typical of those concerned by our biochemical applications. The sensitivity with a 300 nm thick porous sensing layer was 10 times that of the bare device, with interesting dynamical issues to be further studied, giving rise to the great potentialities of such architectures for biological detection of low weight biochemical targets.
关键词： surface to volume ratio,mesoporous materials,biochemical sensing,Radio Frequency Love wave device,finite element modelling,acoustic interaction in liquid medium
更新于2025-09-10 09:29:36
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Photocatalytic activity of Cu2O/ZnO nanocomposite for the decomposition of methyl orange under visible light irradiation
摘要： ZnO is modified by Cu2O by the process of precipitation and calcination. X-ray diffraction has shown that Cu2O/ZnO catalysts are made of highly purified cubic Cu2O and hexagonal ZnO. Scanning electron microscopy and transmission electron microscopy have shown that ZnO adhered to the surface of Cu2O. Due to the doping of Cu2O, the absorption range of the Cu2O/ZnO catalyst is shifted from the ultraviolet to the visible region due to diffuse reflection. X-ray photoelectron spectroscopy and photoluminescence spectra have confirmed that there is a substantial interaction between the two phases of the resultant catalyst. The degradation efficiency of Cu2O/ZnO on methyl orange solution is obviously enhanced compared to Cu2O and ZnO. The maximum degradation efficiency is 98%. The degradation efficiency is affected by the pH of the solution and initial concentration. After three rounds of recycling, the degradation rate is almost same. This shows a consistent performance of Cu2O/ZnO. The increase in catalytic ability is related to the lattice interaction caused by the doping of Cu2O.
关键词： lattice interaction,Cu2O/ZnO,methyl orange,visible photocatalysis
更新于2025-09-10 09:29:36
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Interference Induced Enhancement of Magneto-Optical Effect in Pt/TbCo Hetero-Structured Films
摘要： Magnetic ?lms with a heavy metal layer show strong interfacial interaction of spin-orbit. Spin-orbit interaction is one of the key technologies for spintronics. In this paper, we measured magneto-optical Kerr spectra of Pt/TbCo hetero-structure ?lms on a thermally oxidized silicon substrate (0.3 mm); A: Pt (3 nm)/TbCo (6 nm)/Pt (3 nm), B: Si3N4 (10 nm)/TbCo (6 nm)/Pt (3 nm), and C: Pt (3 nm)/TbCo (6 nm)/Si3N4 (10 nm). Magneto-optical Kerr spectra of each sample were measured with a wavelength range of 300–700 nm, and were compared to the simulated spectra using the effective refractive index method. In the sample A, which has a symmetric structure, the simulated spectra are consistent with the measured ones. On the other hand, in the samples B and C, with an asymmetric structure, there are some differences between the simulated spectra and the measured ones in a lower photon energy region. This may be caused by interfacial effects of the spin-orbit interaction.
关键词： spin-orbit interaction,heavy metal,hetero structure,magnetooptical,TbCo
更新于2025-09-10 09:29:36
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Use of Aggregation-Induced Emission for Selective Detection of Phase Transformation during Evaporative Crystallization of Hexaphenylsilole
摘要： Crystallization of organic molecules is quite complicated because the crystallization process is governed by the weak intermolecular interactions. By exploiting the aggregation-induced emission (AIE), we attempted to realize the selective detection of phase transformation during the evaporative crystallization of hexaphenylsilole (HPS), which shows different fluorescence colors in the amorphous and crystalline phases. No fluorescence emission was observed in the HPS solution immediately after dropping on the glass substrate due to the non-radiative deactivation induced by intramolecular rotational or vibrational motion, suggesting that HPS exists as a monomer in solution. As time elapsed after dropping, green emission first appeared, which changed to blue after solvent evaporation, because of phase transformation from the amorphous state to the crystalline state. This phenomenon supports not only the two-step nucleation model involving an intermediate such as a liquid-like cluster prior to nucleation, but also the real time-detection of Ostwald’s rule of stages during evaporative crystallization.
关键词： molecular interaction,amorphous-crystal phase transformation,AIE,Ostwald’s rule of stages,evaporative crystallization
更新于2025-09-10 09:29:36
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Revealing structural modifications in thermomechanical reshaping of collagenous tissues using optical coherence elastography
摘要： Moderate heating of such collagenous tissues as cornea and cartilages by IR-laser irradiation is an emerging technology for non-destructive modification of the tissue shape and microstructure for a variety of applications in ophthalmology, otolaryngology, etc. Post-irradiation high-resolution microscopic examination indicates the appearance of microscopic either spheroidal or crack-like narrow pores depending on the tissue type and irradiation regime. Such examinations usually require special tissue preparation (e.g., staining, drying that affect microstructure themselves) and are mostly suitable for studying individual pores, whereas evaluation of their averaged parameters, especially in situ, is challenging. Here, we demonstrate OCT’s ability to visualize areas of pore initiation and evaluate their averaged properties by combining visualization of residual irradiation-induced tissue dilatation and evaluation of the accompanying Young-modulus reduction by OCT-based compressional elastography. We show that the averaged OCT-based data obtained in situ fairly well agree with the microscopic examination results. The results obtained develop the basis for effective and safe applications of novel non-destructive laser technologies of tissue modification in clinical practice.
关键词： OCT elastography,strain mapping,Optical coherence tomography,laser-tissue interaction,phase-resolved OCT,thermo-mechanical cornea reshaping
更新于2025-09-10 09:29:36
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A novel protein binding strategy for energy-transfer-based photoelectrochemical detection of enzymatic activity of botulinum neurotoxin A
摘要： In this work, we propose a novel energy-transfer-based photoelectrochemical (PEC) platform for probing of protein-protein interaction, which associates intimately with zinc-dependent cleavage and substrate specificities in the enzymatic activities of botulinum neurotoxin (BoNT). Specifically, by using substrate protein SNAP-25 as the energy-transfer nanoprobe, an exciton-plasmon interaction (EPI) based strategy between CdS quantum dots (QDs) and Au nanoparticles (NPs) in a PEC system is constructed with the photocurrent declining. Interestingly, the EPI effect is then interrupted by the target botulinum neurotoxin serotype A light chain (BoNT-LCA) special cleavage of the probe SNAP-25, leading to the photocurrent recovery. Therefore, the enzymatic activity of BoNT-LCA could be sensitively detected with a detection limit of 1 pg/mL. Unlike conventional DNA-programable assembly, a protein probe is used to bridge the excitons and plasmons in this work, which provides a new route for the investigation of the EPI-based bioassay.
关键词： CdS QDs,Exciton–plasmon interaction,Energy transfer,Botulinum neurotoxin A,Photoelectrochemical detection
更新于2025-09-10 09:29:36
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Low-temperature elemental mercury removal over TiO2 nanorods-supported MnOx-FeOx-CrOx
摘要： TiO2 nanorods-supported MnOx, FeOx, CrOx, and MnOx-FeOx-CrOx catalysts have been prepared by a deposition-precipitation method, with the aim of investigating the combination of ternary metal oxides effect on elemental mercury (Hg0) removal. The TiO2 nanorods-supported MnOx-FeOx-CrOx catalyst manifested the superior Hg0 removal efficiency (~80-83%) at low temperatures (100-200°C) in the presence of O2. The addition of NO promoted the Hg0 removal efficiency under the same reaction conditions. Further, SEM, HRTEM, XRD, BET surface area, and XPS characterization were carried out to explore the physicochemical properties of the catalysts. It was found that the integration of three active metal oxides contributed to the enrichment of active sites and the surface adsorbed oxygen species, which facilitated to enhance the catalytic activity. Additionally, both the large surface area and high crystallization of the obtained TiO2 nanorods resulted in uniform dispersion of the manganese-iron-chromium mixed metal oxide nanoparticles and a high activity. Further, XPS data of spent MnOx-FeOx-CrOx/TiO2 catalyst indicated that the presence of Mn4+, Cr6+, and Fe3+ could promote Hg0 oxidation due to the strong synergistic interaction between the TiO2 nanorods-incorporated MnOx, FeOx, and CrOx nanoparticles.
关键词： Deposition-precipitation,MnOx-FeOx-CrOx,Synergistic interaction,TiO2 nanorods,Flue gas,Hg0 removal
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Nanodot-Molecule Junctions: Assessing Intermolecular Interactions and Electron Transport at Microwave Frequencies
摘要： Here, we present the properties of molecular junctions fabricated on a large array of sub-10 nm single crystal Au nanodot electrodes, each junction being made of less than one hundred molecules. Thanks to this approach, we discuss some pending issues in molecular electronic : (i) the determination of inter-molecular interactions from the conductance histograms of molecular junctions, (ii) the demonstration of molecular electronic devices for high-frequency operation with a molecular diode working in the microwave regime up to 18 GHz.
关键词： Molecular electronics,interaction energy,scanning microwave microscope,microwave,electron transport,conducting-AFM
更新于2025-09-10 09:29:36