Hybrid Multi-Infeed Receiver Line Longitudinal Protection Scheme Based on Voltage Waveform Comprehensive Distance Similarity.

The coupling of AC and DC power will impact the protective actions on the AC side and pose a threat to the stable operation of the interconnection system. Therefore, a new longitudinal protection method is proposed based on the comprehensive distance similarity of voltage waveforms. Initially, the measured voltage and current data are extracted to calculate the reference voltage, and the voltage waveform fitting is optimized. Subsequently, the Euclidean dynamic time warp (DTW) distance and entropy weight method are utilized to process the voltage waveform, enabling the calculation of its comprehensive distance similarity. This similarity is adopted to determine fault location. A hybrid DC multi-feed AC/DC interconnection system, incorporating a line commutated converter-voltage source converter (LCC-VSC) and a line commutated converter-modular multilevel converter (LCC-MMC), was established in PSCAD, and fault data were simulated and output. The effectiveness of the protection scheme was validated using MATLAB. Simulation results demonstrate that the proposed method can accurately distinguish between faults inside and outside a region. When compared to existing protection methods, it demonstrates superior performance in resisting transition resistance and noise interference, while also mitigating the impact of data asynchronicity. The speed and reliability of the method are further enhanced.

Enhanced Sensing Performance of SnX Ti1-X O2 -TiX Sn1-X O2 Core-Shell Heterostructure via Increasing the Density of Unsaturated Sn and Ti Atoms.

The strategy of combining different semiconductor materials is adjudged an effective approach to improve the sensing performances of semiconductor materials. However, the specific synergistic mechanism for the excellent gas-sensitive performances of composite materials has not been elucidated. Herein, a facile solvothermal method is employed to synthesize SnX Ti1-X O2 -TiX Sn1-X O2 core-shell heterostructures using SnCl4 •5H2 O and tetrabutyl titanate (TBOT) as raw materials. When the molar ratio of SnCl4 •5H2 O/TBOT is 1.8/3.0, the afforded composite exhibited the highest gas sensing performances compared with other composites prepared with other molar ratios. The enhanced sensing performance is attributed to the simultaneous incorporation of Sn and Ti ions into each other's lattice, leading to an increase in the density of unsaturated Sn and Ti atoms on the surface. Ultimately, more oxygen vacancies are formed by the unsaturated Sn and Ti atoms, which benefits electron capture and the redox reaction of adsorbed gases. Thus, the concept of increased unsaturated metal atoms and oxygen vacancy resulting from the doping of different metal ions into each other's lattice has deepened the understanding of gas sensing and the catalytic reaction mechanisms. The lattice synergy of different metals provides a pathway for the design of advanced gas-sensing materials and catalysts.

Increasing the bioactivity of kynurenine by ultraviolet irradiation via resonance energy transfer in vitro.

Kynurenine (Kyn) is involved in a variety of physiological/pathological reactions via activating aryl hydrocarbon receptor (Ahr). However, how to activate Ahr by Kyn under physiological/pathological conditions is still unclear. Here, we presented that Kyn (8 µM, a concentration less than the dose of Kyn-induced Ahr activation) significantly induced the nuclear transfer of Ahr and the expression of cytochrome P450 1A1 (CYP1A1, a classic biomarker for Ahr activation) when co-administered with ultraviolet (UV) irradiation in 95D cells, which were transfected transiently with siRNA against indoleamine 2,3-dioxygenase 1 (IDO 1) and cultured in cell medium supplemented with bovine serum containing bovine serum albumin (BSA), in vitro. Additionally, we found that the fluorescence intensity of BSA was attenuated by Kyn (2, 4, 6, 8, 10, 12 and 14 µM) mainly through quenching the fluorescence of tryptophan (Trp) residues in the pattern of dynamic quenching related to molecular diffusion. More important, resonance energy transfer from excited-state BSA to Kyn was confirmed, leading to the generation "energetic" Kyn that might be ability of hyperactivity according to the theory of photochemical reaction. These data indicate that UV irradiation is contributable for Kyn to function, and present a novel pattern of altering the activity of biomolecules to some degree.

Attenuation of antigenic immunogenicity by kynurenine, a novel suppressive adjuvant.

A novel therapeutic strategy is required for autoimmune diseases characterized by the production of autoantibody, because current clinical strategies have limitations. Vaccination against autoimmune diseases is a feasible strategy because vaccines induce immune response memory and the antigen specificity. However, no suitable adjuvant is available to direct the immune response toward tolerance or suppression. In the current study, we evaluated whether kynurenine (Kyn) could serve as a novel suppressive adjuvant to decrease the humoral immune responses against hepatitis A virus (HAV) in the ICR mouse model in vivo and lipopolysaccharide (LPS) in B cells in vitro. The underlying mechanisms of Kyn-mediated suppression of LPS-induced IgM responses were explored. The results showed that Kyn significantly decreased HAV immunogenicity when co-administered with HAV, and that Kyn (100 µM/1000 µM) impaired IgM generation compared with that induced by LPS alone. We also demonstrated that microRNA30b (miR30b) played a critical role in the process of Kyn-mediated suppression of IgM responses induced by LPS, and that Bach2, a transcriptional repressor of B cell terminal differentiation, was a novel target of miR30b. These findings suggest that Kyn can serve as a novel and effective suppressive adjuvant for vaccines.

[Study on rapid determination of active ingredient of agrochemicals by near-infrared spectroscopy].

The main problem of disqualification of the agrochemicals is the insufficiency and abuse of its active ingredient, but lacking of the rapid and on the site analysis method. In the present thesis, the content of haloxyfop-r-methyl in the emulsifiable concentration was analyzed quantitatively by the FT-NIR spectroscopy combined with partial least square (PLS) method. The calibration models of haloxyfop-r-methyl were developed, the determination coefficients (R2) of the calibration models were no less than 0.999 9, the SEC were less than 0.019, and the SEP were less than 0.030. Meanwhile, the factors affecting the calibration model were studied and the validation was done by the actual sample. The result indicated that the method of near-infrared spectroscopy can predict the content of the active ingredient in emulsifiable concentration accurately; while the resolution of the instrument and the content of addition agent will not affect the prediction precision of the calibration model remarkably. Therefore, it is a feasible, convenient and quick method to analyze the active ingredient in the commodity agrochemicals by near-infrared spectroscopy, which has an important significance in the on-line determination, analysis on site in the enterprise and the rapid quantitative analysis of agrichemicals in the department of quality monitoring.

[Spectrofluorimetric study of supramolecular inclusion between rodenticide brodifacoum and beta-cyclodextrin and application].

The supramolecular interaction between beta-cyclodextrin and brodifacoum, an anticoagulant rodenticide of the second generation, was studied by spectroscopy. The results showed that brodifacoum and beta-cyclodextrin could form an inclusion complex with an association constant of 1.048 x 10(4) L x mol(-1) and a 1 : 1 stoichiometry based on Benesi-Hildebrand equation. The inclusion mechanism was proposed to explain the inclusion mode. It was indicated that the hydrophobic group of brodifacoum molecule, biphenyl, entered into the cavity of beta-cyclodextrin. At the same time, it was also observed the significant enhancement of fluorescence of brodifacoum after forming inclusion complex. According to the fluorescence enhancement phenomenon, a spectrofluorimetric method of detecting brodifacoum in aqueous media was established with the linear range of 8.0 x 10(-8)-4.0 x 10(-6) mol x L(-1) and the correlation coefficient of 0.999 4. The detection limit of the method was 8.8 x 10(-9) mol x L(-1). The proposed method was successfully applied to determine the trace amount of brodifacoum in environment water and the recovery was in the range of 87.3% to 103.9%.

[Study of the interaction mechanism between brodifacoum and DNA by spectroscopy].

The interaction between brodifacoum (3-[3-(4'-bromophenyl-4) 1,2,3,4-tetralin-10]-4-hydroxyl-coumarin) (BDF), an anticoagulant rodenticide, and calf thymus DNA (ct-DNA) was studied by UV spectrum and fluorescence spectrum. The results were summarized as follows: There was a hypochromic effect of low concentration ct-DNA on the UV spectra. The fluorescence quenching studies showed a regular decrease in the fluorescence intensity after addition of ct-DNA by the static quenching mode with a quenching constant (Ksv) of 1.21 x 10(4) L x mol(-1) at 27 degrees C. The BDF possibly bonded to ct-DNA mainly via Van der Waals forces by the corresponding thermodynamics parameter. KI quenching experiment found that there was not obvious protection of ct-DNA to BDF. The fluorescence intensity of BDF/ct-DNA system changed with the variation in ionic strength Quenching of ct-DNA on the fluorescence of BDF/beta-CD inclusion complex was reduced in contrast with the free BDF, which showed that beta-CD could provide BDF with protection. So the comprehensive interaction mode of BDF with ct-DNA may be the groove binding by the above results. It was indicated that there had been static-electro interaction between BDF and ct-DNA at the same time. The conjunct action of Van der Waals forces and electrostatic attraction favorably provide BDF bonding interaction in the groove of ct-DNA.

[Spectroscopic study on interaction of rodenticide brodifacoum with bovine serum albumin].

The mutual interaction of bovine serum albumin (BSA) with brodifacoum (3-[3-(4'-bromophenyl-4) 1,2,3,4-tetralin-10]-4-hydroxyl-coumarin), an anticoagulant rodenticide, was investigated by ultra-violet spectroscopy, flurorescence spectroscopy and synchronous fluorescence spectroscopy under physiological conditions. It was proved that the intrinsic fluorescence quenching of BSA by brodifacoum was the result of the formation of brodifacoum-BSA complex. And this quenching is mainly due to static fluorescence quenching. The quenching rate constant (K(sv)), binding site number (n) and binding constant (KA) at different temperatures were calculated from the double reciprocal Lineweaver-Burk plots and the quenching function of lg[(F0 - F)/F] - lg[Q] plots. The thermodynamic parameters indicated that the process of binding was a spontaneous molecular interaction and the hydrophobic force played a major role in stabilizing the brodifacoum BSA complex. The binding distance r between brodifacoum and BSA was 2.84 and 2.87 nm at 20 and 30 degrees C, respectively, which was obtained based on Forster theory of non-radiation energy transfer. The synchronous spectroscopy of BSA and brodifacoum-BSA revealed that the BSA conformation had changed in the presence of brodifacoum. The binding mode and interaction mechanism were suggested as follows: brodifacoum molecules are closed with amino acid residues with electric charge on the hydrophobic cavities of BSA by electrostatic interaction, and binded to the Trp212 residues inside of BSA hydrophobic cavities by hydrophobic interaction force, thereby changed the microenvironment around the Trp residues. The interaction prevented the energy transfer between Tyr and Trp residues, moreover, caused to a non-radiation energy transfer from Trp residues in BSA to brodifacoum, and finally leaded of the quenching the intrinsic fluorescence of BSA.