MicroRNAs, as oncogenes or tumor suppressors, enable to up or down-regulate gene expression during tumorigenesis. The detection of miRNAs with high sensitivity is crucial for the early diagnosis of ...cancer. Inspired by biological ion channels, artificial nanochannels are considered as an excellent biosensing platform with relatively high sensitivity and stability. The current nanochannel biosensors are mainly based on homogeneous membranes, and their monotonous structure and functionality limit its further development. Therefore, it is necessary to develop a heterostructured nanochannel with high ionic current rectification to achieve highly sensitive miRNA detection.
In this work, an asymmetric heterostructured nanochannel constructed from dendrimer-gold nanoparticles network and anodic aluminum oxide are designed through an interfacial super-assembly method, which can regulate ion transport and achieve sensitive detection of target miRNA. The symmetry breaking is demonstrated to endow the heterostructured nanochannels with an outstanding ionic current rectification performance. Arising from the change of surface charges in the nanochannels triggered by DNA cascade signal amplification in solution, the proposed heterogeneous nanochannels exhibits excellent DNA-regulated ionic current response. Relying on the nucleic acid's hybridization and configuration transformation, the target miRNA-122 associated with liver cancer can be indirectly quantified with a detection limit of 1 fM and a wide dynamic range from 1 fM to 10 pM. The correlation fitting coefficient R2 of the calibration curve can reach to 0.996. The experimental results show that the method has a good recovery rate (98%–105 %) in synthetic samples.
This study reveals how the surface charge density of nanochannels regulate the ionic current response in the heterostructured nanochannels. The designed heterogeneous nanochannels not only possess high ionic current rectification property, but also enable to induce superior transport performance by the variation of surface chemistry. The proposed biosensor is promising for applications in early diagnosis of cancers, life science research, and single-entity electrochemical detection.
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•The symmetry breaking endows the nanochannels with an outstanding ionic current rectification property.•An enlarged ion current signal of target miRNA can be achieved by DNA cascade amplification.•The designed biosensor can detect miRNA-122 as low as 1 fM.•The designed biosensors can be extended to the detection of charged molecules.
Deep-learning-based registration methods can not only save time but also automatically extract deep features from images. In order to obtain better registration performance, many scholars use cascade ...networks to realize a coarse-to-fine registration progress. However, such cascade networks will increase network parameters by an n-times multiplication factor and entail long training and testing stages. In this paper, we only use a cascade network in the training stage. Unlike others, the role of the second network is to improve the registration performance of the first network and function as an augmented regularization term in the whole process. In the training stage, the mean squared error loss function between the dense deformation field (DDF) with which the second network has been trained and the zero field is added to constrain the learned DDF such that it tends to 0 at each position and to compel the first network to conceive of a better deformation field and improve the network's registration performance. In the testing stage, only the first network is used to estimate a better DDF; the second network is not used again. The advantages of this kind of design are reflected in two aspects: (1) it retains the good registration performance of the cascade network; (2) it retains the time efficiency of the single network in the testing stage. The experimental results show that the proposed method effectively improves the network's registration performance compared to other state-of-the-art methods.
In the development of precast shear wall structures, reliable and efficient connections of precast units are crucial for their seismic behavior. Meanwhile, the heavy precast units using conventional ...concrete bring a low lifting efficiency. Considering these issues, the paper proposed a novel type of socket vertical joint for precast shear walls made of steel fiber reinforced lightweight aggregate concrete (SFRLAC). Sixteen socket connection specimens, with four socket depths (100 mm, 150 mm, 200 mm, and 250 mm) and two interface treatments (smooth and exposed aggregate), underwent interface bonding performance tests using uniaxial tensile testing and finite element (FE) numerical models to determine the appropriate socket depth. Three specimens were tested using the low-cyclic loading test, including two reinforced SFRLAC precast shear walls assembled with a socket vertical joint and a cast-in-place reinforced SFRLAC shear wall as a reference. The failure patterns and process of the shear walls were observed, while the load-displacement curves were obtained. Additionally, a parametric analysis of different influencing factors was conducted using finite element (FE) numerical models. This analysis studied the bearing capacity, energy dissipation capability, deformation ability, and stiffness degradation of the shear walls. Results indicate that when the precast shear walls were damaged, the socket vertical joint was integrity and failed in bending-shear. The three specimens exhibited fewer differences in seismic behavior with relatively full hysteretic curves. The seismic mechanisms of the shear wall assembled with a socket vertical joint were elucidated by analyzing the numerical distribution of stress in both SFRLAC and steel bars at different stress levels. Furthermore, an expansion analysis was conducted to assess the impact of axial load ratios and shear to span ratios on the seismic behavior of precast shear walls.
The Rashba effect plays a vital role in electronic structures and related functional properties. The strength of the Rashba effect can be measured by the Rashba parameter αR; it is desirable to ...manipulate αR to control the functional properties. The current work illustrates how αR can be systematically tuned by doping, taking BiTeI as an example. A five-point-spin-texture method is proposed to efficiently screen doped BiTeI systems with the Rashba effect. Our results show that αR in doped BiTeI can be manipulated within the range of 0–4.05 eV Å by doping different elements. The dopants change αR by affecting both the spin–orbit coupling strength and band gap. Some dopants with low atomic masses give rise to unexpected and sizable αR, mainly due to the local strains. The calculated electrical transport properties reveal an optimal αR range of 2.75–3.55 eV Å for maximizing the thermoelectric power factors. αR thus serves as an effective indicator for high-throughput screening of proper dopants and subsequently reveals a few promising Rashba thermoelectrics. This work demonstrates the feasibility of defect-mediated Rashba engineering for optimizing the thermoelectric properties, as well as for manipulating other spin-related functional properties.
A low‐cost array flexible surface‐enhanced Raman spectroscopy (SERS) chip was proposed with the aim of rapid detection of bacteria. The substrate of the chip was Al foil, and the detection area ...arrays were printed using a laser toner. Colloidal silver nanoparticles (AgNPs) were dropped onto the detection area, with the AgNPs droplets confined within the detection area by the hydrophobic properties of the toner film. The colloidal AgNPs were dried naturally to form a SERS active chip. An A4 paper‐based SERS chip was prepared using the same method for control experiments. The surface morphology of the chip was characterized by field emission scanning electron microscopy. In addition, comparison experiments were performed on the two SERS chips. The results showed that both SERS chips exhibited the best SERS enhancement when the AgNPs were added four times. The calculation of Rhodamine 6G at the 612 cm−1 peak showed that the EF of the A4 paper‐based chip and the Al foil‐based chip were 6.72 × 107 and 1.03 × 108, respectively. SERS mapping results showed that the Al foil‐based chip had much higher signal homogeneity than that of A4 paper‐based chip. Lastly, the Al foil‐based chip was used for bacterial detection. For Escherichia coli and Staphylococcus aureus, the limit of detection was 1,000 and 100 cfu/ml, and the relative standard deviation of 36 randomly selected detection points were 12.5% and 11.7%, respectively. The entire detection process was completed in a few minutes. The SERS chip has the advantages of low cost, simple manufacturing process, and short detection time; is capable of high throughput and multi‐parameter detection; and is expected to provide a rapid and effective detection method for bacteria.
An array flexible SERS chip for rapid bacterial detection is fabricated by printer‐assisted and drop‐casting methods, which is easy to mass‐produce at low cost. The Raman enhancement performance of Al foil‐based SERS chip is obviously better than that of A4 paper‐based chip. The experimental results showed that the Al foil‐based SERS chip has good uniformity and can achieve rapid and label‐free detection of E. coli and S. aureus.
To investigate the effect of improved property rights and, in particular, village democracy under China’s Collective Forest Tenure Reform (Tenure Reform) on household forestry investments, we ...estimate both tobit models and the more general Cragg models for farmers’ labor and monetary inputs into forestry, using survey data of 652 households from the southern collective forest region of China. The results reveal that the improved forestland use and disposition rights had a significant effect on household investments in forestry, while the beneficiary right did not. In addition, the results suggest that village democracy had a positive effect on households’ forestry investments. More importantly, we find that village democracy was able to significantly strengthen the investment incentive effect of the improved property rights under the Tenure Reform. These effects may be explained by the fact that village democracy improved households’ perception, cognition, and, subsequently, confidence toward, in particular, the use and disposition rights of the forests entitled to them. Therefore, the findings suggest that to increase the investment incentives of the Tenure Reform further, governments could strengthen the bundle of households’ use and disposition rights, as well as their related policies. Also, our findings indicate that governments could significantly improve the performance of public policies by effectively employing democratic procedures in the process of policy implementation.
Indentation experiments on differently oriented faces of monocrystalline copper were conducted to investigate the micro-deformation process at temperatures ranging from room temperature to 150 K. The ...morphologies and textures of the residual imprints were observed using electron microscopy. Distinct slip bands were observed inside the imprints at 150 K compared to smooth surfaces at room temperature. Molecular dynamics simulations were performed to identify the deformation process beneath the indentation region. The results showed that plastic deformation was inhibited with decreasing temperature, but elastic recovery during the unloading process was enhanced, resulting in inner slip bands (ISBs) being observable in the residual imprints. The performances of these ISBs were strongly associated with the angles between the indentation direction and major slip surfaces and could be considered microscopic forms on the surfaces of aggregated geometrically necessary dislocations (GNDs). This work helped reveal the micro-deformation mechanism of indentations inside imprints.
Multimodal medical images can be used in a multifaceted approach to resolve a wide range of medical diagnostic problems. However, these images are generally difficult to obtain due to various ...limitations, such as cost of capture and patient safety. Medical image synthesis is used in various tasks to obtain better results. Recently, various studies have attempted to use generative adversarial networks for missing modality image synthesis, making good progress. In this study, we propose a generator based on a combination of transformer network and a convolutional neural network (CNN). The proposed method can combine the advantages of transformers and CNNs to promote a better detail effect. The network is designed for positron emission tomography (PET) to computer tomography synthesis, which can be used for PET attenuation correction. We also experimented on two datasets for magnetic resonance T1- to T2-weighted image synthesis. Based on qualitative and quantitative analyses, our proposed method outperforms the existing methods.
Farmers′ awareness of forest-based bioenergy developments will greatly determine the direction and succession of forestry projects. To obtain a better understanding of this awareness, a logistic ...regression model was applied to analyze the factors influencing farmers′ willingness to participate in the construction of bioenergy bases. The model was developed based on a survey of 573 household farmers in eight Chinese provinces. This study found that a majority of households have increased their daily use of commercial fuel. Moreover, a significant number of farmers are either uncertain about or unfamiliar with the concept of forest-based bioenergy. The model found that households with young and educated individuals, a higher forestland endowment, and a higher cognition and understanding of fossil fuels, have a higher willingness to learn about and participate in forest based bioenergy issues. The findings of this study will be useful for bioenergy forest cultivators, extension foresters, forest landowners, and policy makers.
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