RESUMEN

Existing studies have not analyzed travelers' travel modal shift behavior after bus fare adjustment for special urban topography. In order to fill this gap and explore the strategies that can effectively encourage the shift of valley city travelers to rail transit after the adjustment of bus fare, the price adjustment perception and topographic space perception are introduced to expand the theory of planned behavior (TPB). On this basis, an integrated model combining structural equation model (SEM) and Mixed Logit model (MLM) is established to analyze the factors of travelers' modal shift behavior of in the valley city after bus fare adjustment, and elastic analysis is carried out. Taking Lanzhou as an example, questionnaire data and traffic data were collected for example analysis. The results show that fare adjustment perception (FAP) and topographic space perception (TSP) have the same significant impact on travel modal shift intention (TMSI) and behavior (TMSB) as subjective norms (SN), shift behavior attitude (SBA) and perceived behavior control (PBC), and the travel characteristics and psychological perception sensitivity of travelers in the valley city are heterogeneous. After the adjustment of bus fares in valley city, the shift to rail transit is the most. When the subjective norms, fare adjustment perception and topographic space perception of travelers in the valley city increase by 50 %. The sharing rate of rail transit is increased by 10.284 %. The effective way to increase the sharing rate of rail transit is to increase the combined factors of subjective norms, topographic space perception and fare adjustment perception. Compared with the Multinomial Logit model and the Logit model combined with structural equation model, the goodness of fit and prediction accuracy of the proposed integrated model are improved.

RESUMEN

Existing research rarely examines the subjective and objective built environment of river valley-type cities in relation to travel mode choice, particularly overlooking the heterogeneity among travelers in these cities. In this paper, based on questionnaire survey data and built environment data, terrain spatial perception (TSP) is introduced to expand the theory of planned behavior (TPB), and a Structural Equation Model (SEM) is established. Factor analysis and path analysis are conducted using SPSS and AMOS to estimate latent variables. An integrated model of SEM and random parameter Logit model (RPLM), which can not only analyze the psychological perception factors of commuters in river valley-type cities but also consider the heterogeneity of psychological perception, was constructed to analyze the impact of personal attributes, objective built environment factors, and psychological latent variables on the commuting mode choice behavior of public transport users in river valley-type cities. The results indicate that the five observation indicators corresponding to the proposed terrain spatial perception latent variables can better explain the terrain spatial perception of commuters in river valley-type cities. Different from plain cities, the subjective and objective built environment of river valley-type cities notably influence the travel behavior of commuters. Moreover, the parameters of terrain spatial perception follow a normal distribution, indicating that the sensitivity of different commuters to the terrain spatial perception of river valley-type cities is heterogeneous. The results of our study can provide a reference for alleviating traffic issues in valley cities.

RESUMEN

The detection of sequence-specific microRNAs (miRNAs) is an important factor to the diseases diagnosis. Herein, a triple signal amplification electrochemical biosensor for highly sensitive detection of miRNA-21 was developed based on a duplex-specific nuclease (DSN)-assisted target recycling combined with gold nanoparticles (NPs), horseradish peroxidase (HRP) enzymatic signal amplification. The electrochemical biosensor generated significantly amplified amperometric current changes (Δi) for the detection of miRNA-21 down to 43.3 aM, and Δi was proportional to the logarithm of the concentration of miRNA-21 within the range of 0.1 fM to 100 pM. Meanwhile, the inherent selectivity of the term hairpin capture probe endowed the biosensor with high differentiation of similar miRNAs. The good feasibility of the proposed strategy for cell miRNA detection was confirmed by analyzing miRNA-21 in A549 lysates, which indicates its promising potential in biomedical research and clinical analysis.

Asunto(s)

RESUMEN

DNA demethylation and demethylase activity play important roles in DNA self-repair, and their detection is key to early diagnosis of fatal diseases. Herein, a facile electrochemical DNA (E-DNA) sensor was developed for the sensitive detection of DNA demethylation and demethylase activity based on an enzyme cleavage strategy. The thiol modified hemi-methylated hairpin probe DNA (pDNA) was self-assembled on a Au electrode surface through the formation of AuS bonds. The hemi-methylated pDNA served as the substrate of DNA demethylase (using methyl-CpG-binding domain protein 2 (MBD2) as an example). Following demethylation, the hairpin stem was then recognized and cleaved by BstUI endonuclease. The ferrocene carboxylic acid (FcA)-tagged pDNA strands were released into the buffer solution from the electrode surface, resulting in a significant decrease of electrochemical signal and providing a means to observe DNA demethylation. The activity of DNA demethylase was analyzed in the concentration ranging from 0.5 to 500 ng mL(-1) with a limit of detection as low as 0.17 ng mL(-1). With high specificity and sensitivity, rapid response, and low cost, this simple E-DNA sensor provides a unique platform for the sensitive detection of DNA demethylation, DNA demethylase activity, and related molecular diagnostics and drug screening.

Asunto(s)

RESUMEN

Au-SnO2 hybrid nanospheres (HNSs) were synthesized by a facile, one-step method, which was achieved via a redox reaction between the reductive stannous (II) ions and oxidative auric (III) ions and dissolved O2, and then in situ formation of Au nanoparticles (NPs) and SnO2 NPs. The results indicated that the Au NPs are able to trap electrons, improve the electron-hole pairs' life, and enhance the visible light absorption intensity that are all beneficial for enhancement of the visible light photoelectrochemical performance. Cysteine was chosen as a model molecule in photoelectrochemical biosensing experiments. The biosensor displayed excellent analytical performance for detection of cysteine with an extremely broad linear range (from 0.4 µM to 12 mM), and a low detection limit (0.1 µM). Therefore, the Au-SnO2 HNSs will be promising candidates for photocatalysts, photoelectrochemical biosensors, and other photoelectric devices.

Asunto(s)

RESUMEN

We report a new strategy for detection of the methylation level and position in the Hsp53 tumor suppressor gene based on the electrochemiluminescence signal amplification combined with a conformation-switched hairpin DNA probe for improving selectivity.

Asunto(s)