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Cracks are a common type of road distress. However, the traditional manual and vehicle-borne methods of detecting road cracks are inefficient, with a high rate of missed inspections. The development of unmanned aerial vehicles (UAVs) and deep learning has led to their use in crack detection and classification becoming an increasingly popular topic. In this paper, an aerial drone is used to efficiently and safely collect road data. However, this also brings many challenges. For example, flying too high or too fast may produce poor quality images, with unclear cracks that may be ignored or misjudged as other features and increased environmental noise that may make it difficult to distinguish between cracks and other noise features. To address the above challenges, this paper proposes the CrackNet model and CrackClassification algorithm. The CrackNet network is an encoder–decoder architecture. Low- and high-level semantic information are combined through the skip feature fusion layers between the encoder and decoder to enhance the model’s expression and ability to recover image details. Additionally, the MHDC module at the bottom of the network can significantly increase the receptive field without reducing the feature map resolution. The MHSA module can simultaneously capture features from multiple subspaces. The average precision (AP) scores of the CrackNet network on three datasets, namely UAVRoadCrack, CRKWH100, and CrackLS315, were 0.665, 0.942, and 0.895, respectively. In addition, values of the other two evaluation metrics, ODS and OIS, were the highest among the compared methods. Meanwhile, the proposed CrackClassification algorithm in this paper achieves 85% classification accuracy for transverse and longitudinal cracks and 78% classification accuracy for block cracks and reticulated cracks. Overall, the CrackNet algorithm provides a new baseline model for crack detection in UAV remote sensing image scenes. The CrackClassification algorithm provides a new approach for batch classification of highway cracks. The detection and classification algorithm proposed in this paper were applied to 108 km of road sections.

This paper proposed a novel intracellular drug delivery system consisting of mesoporous silica nanoparticles (MSN) functionalized on the pore outlets with an acid-labile DNA molecule-gated switch. In this system, a T-Hg

In this paper, a universal analytical current model for a double-gate Si-based tunnel field-effect transistor (TFET) is presented considering the effects of charges in source depletion region and channel. An accurate surface potential model is developed first by solving the pseudo-2-D Poisson equations in the depletion regions, and then is used to calculate the drain tunneling current. The modeling results match well with that obtained from the Technology computer-aided design simulations under various biasing conditions, which indicate that the analytical current model would be very helpful for the further TFET-based circuits design. Furthermore, the influence of the source depletion is also studied, and the presented model with considering the source depletion region and the channel inversion charges is proved to be much more accurate than that ignoring the source depletion.

In this paper, an L-shape tunnel field-effect transistor (LTFET) with gate-drain underlap (GDU-LTFET) is proposed to suppress the ambipolar behavior effectively and to optimize the TFET inverter circuit. As the GDU architecture changes the energy band of the junction between the channel region and the drain region, the GDU-LTFET has lower band-to-band tunneling (BTBT) rate compared with LTFET in the off-state, which helps to reduce static power consumption of TFET digital circuit. The simulation results show that the noise margin, voltage gain and static power consumption in the GDU-LTFET inverter perform better compared with that in the LTFET inverter.

In this paper, a novel planar InAs/Si heterojunction tunnel field-effect transistor (HTFET) is proposed and studied by numerical simulations. Utilizing the large conduction band offset between InAs and Si, the buried drain design with selective doping in the Si substrate instead of the top InAs layer is applied to suppress the Shockley-Read-Hall (SRH) recombination significantly, achieving the off-state current (I OFF ) about two decades lower than the conventional InAs-doped drain. Besides, the face-tunneling technique is also incorporated to place the gate parallel with the InAs/Si tunneling interface. Thus all the points on the tunneling interface are the same distance far away from the gate electrode and the tunneling field is uniformly distributed along the tunneling interface resulting in almost simultaneous carrier tunneling process and very sharp turn on/off switch. In addition, different with most of the HTFET designs, the proposed InAs/Si HTFET with planar device architecture is more preferable for the compatibility with the standard CMOS processes, exhibiting its promising potential for future ultra-low power applications.

A facile method for the shape-selective synthesis of silica nanostructures using a reverse-microemulsion-mediated template (RMMT) technique is reported. In this method, positive poly- l -lysine (PLL) is selected as template due to its configuration diversity. By adjusting pH and concentration, PLL demonstrates various secondary structures containing random coil, α -helix and β -sheet, which result in the formation of silica nanorods, silica nanospheres and silica nanotubes in the reverse-microemulsion system, respectively. Thus, the shape-selective synthesis of silica nanostructures might be achieved by using PLL as structural template in the reverse-microemulsion system.

A novel photon-fueled gate-like mesoporous silica nanoparticles (MSN)-based delivery system is reported. In this system, the malachite green carbinol base (MGCB) is immobilized on the nanochannel wall of MSN as a light-induced hydroxide ion emitter and i-motif DNA is grafted on the surface of MSN as a cap. Photoirradiation with 365 nm wavelength UV light makes MGCB molecules dissociate into malachite green (MG) cations and OH− ions, which induce the i-motif DNA to unfold into the single-stranded form due to the increase of the pH in the solution. Therefore, the pores are uncapped and the entrapped guest molecules are released. After the light is turned off, the MG cations recombine with the OH− ions and return to the MGCB forms. The pH value thus decreases and the single-stranded DNA switches back to i-motif structure to cap the pore again. Because of the photon-fueled MGCB-dependent DNA conformation changes, the i-motif DNA-gated switch can be easily operated by turning the light on or off. Importantly, the opening/closing protocol is highly reversible and a partial cargo release can be easily achieved at will. This proof-of-concept may promote the application of DNA in the controlled release and can also provide a way to design various photon-fueled controlled-release systems using a combination of some photoirradiated pH-jump systems and other kinds of pH-sensitive linkers.

In this paper, a reversible light-responsive molecule-gated system based on mesoporous silica nanoparticles (MSN) functionalized with thymine derivatives is designed and demonstrated. The closing/opening protocol and release of the entrapped guest molecules is related by a photodimerization-cleavage cycle of thymine upon different irradiation. In the system, thymine derivatives with hydrophilicity and biocompatibility were grafted on the pore outlets of MSN. The irradiation with 365 nm wavelength UV light to thymine-functionalized MSN led to the formation of cyclobutane dimer in the pore outlet, subsequently resulting in blockage of pores and strongly inhibiting the diffusion of guest molecules from pores. With 240 nm wavelength UV light irradiation, the photocleavage of cyclobutane dimer opened the pore and allowed the release of the entrapped guest molecules. As a proof-of-the-concept, Ru(bipy)(3)(2+) was selected as the guest molecule. Then the light-responsive loading and release of Ru(bipy)(3)(2+) were investigated. The results indicated that the system had an excellent loading amount (53 μmol g(-1) MSN) and controlled release behavior (82% release after irradiation for 24 h), and the light-responsive loading and release procedure exhibited a good reversibility. Besides, the light-responsive system loaded with Ru(bipy)(3)(2+) molecule could also be used as a light-switchable oxygen sensor.

Mercury (Hg(2+)) is a highly toxic and widespread environmental pollutant. Herein, a regenerable and highly selective core-shell structured magnetic mesoporous silica nanocomposite with functionalization of thymine (T) and T-rich DNA (denoted as Fe3O4@nSiO2@mSiO2-T-TRDNA nanocomposite) has been developed for simultaneous detection and removal of Hg(2+). In this work, the thymine and T-rich DNA were immobilized onto the interior and exterior surface of outermost mesoporous silica, respectively. The detection mechanism is based on Hg(2+)-mediated hairpin structure formed by T-rich DNA functionalized on the exterior surface of the nanocomposites, where, upon addition of SYBR Green I dye, strong fluorescence is observed. In the absence of Hg(2+), however, addition of the dye results in low fluorescence. The limit of detection for Hg(2+) in a buffer is 2 nM by fluorescence spectroscopy. Simultaneously, the Fe3O4@nSiO2@mSiO2-T-TRDNA nanocomposite features a selective binding with Hg(2+) between two thymines immobilized at the interior surface of the mesopores and exhibits efficient and convenient Hg(2+) removal by a magnet. Kinetic study reveals that the Hg(2+) removal is a rapid process with over 80% of Hg(2+) removed within approximately 1 h. The applicability of the developed nanocomposites is demonstrated to detect and remove Hg(2+) from samples of Xiangjiang river water spiked with Hg(2+). In addition, distinguishing aspects of the Fe3O4@nSiO2@mSiO2-T-TRDNA nanocomposites for Hg(2+) detection and removal also include the regeneration using a simple acid treatment and resistance to nuclease digestion. Similar process can be used to functionalize the Fe3O4@nSiO2@mSiO2 nanocomposites with other nucleic acids and small molecules for environmental and biomedical applications.

Adenosine-5'-triphosphate (ATP) is a multifunctional nucleotide, which plays a vital role in many biological processes, including muscle contraction, cells functioning, synthesis and degradation of important cellular compounds, and membrane transport. Thus, the development of ATP-responsive controlled release system for bioorganism application is very significative. Here, an original and facile ATP-responsive controlled release system consisting of mesoporous silica nanoparticles (MSN) functionalized with an aptamer as cap has been designed. In this system, the ATP aptamer was first hybridized with arm single-stranded DNA1 (arm ssDNA1) and arm single-stranded DNA2 (arm ssDNA2) to form the sandwich-type DNA structure and then grafted onto the MSN surface through click chemistry approach, resulting in blockage of pores and inhibition of guest molecules release. In the presence of ATP, the ATP aptamer combined with ATP and got away from the pore, leaving the arm ssDNA1 and ssDNA2 on the surface of MSN. The guest molecules can be released because single-stranded DNA is flexible. The release of the guest molecules from this system then can be triggered by the addition of ATP. As a proof-of-principle, Ru(bipy)(3)(2+) was selected as the guest molecules, and the ATP-responsive loading and release of Ru(bipy)(3)(2+) have been investigated. The results demonstrate that the system had excellent loading efficiency (215.0 μmol g(-1) SiO(2)) and the dye release percentage can reach 83.2% after treatment with 20 mM ATP for 7 h. Moreover, the ATP-responsive behavior shows high selectivity with ATP analogues. However, the leakage of Ru(bipy)(3)(2+) molecule is neglectable if ATP was not added, indicating an excellent capping efficiency. Interestingly, this system can respond not only to the commercial ATP but also to the ATP extracted from living cells. By the way, this system is also relatively stable in mouse serum solution at 37 °C. This proof of concept might promote the application of ATP-responsive devices and can also provide an idea to design various target-responsive systems using other aptamers as cap.

This paper proposed a novel intracellular drug delivery system consisting of mesoporous silica nanoparticles (MSN) functionalized on the pore outlets with an acid-labile DNA molecule-gated switch. In this system, a T–Hg2+–T base pair-mediated double-stranded DNA (dsDNA1) was grafted on the MSN surface as a nanoscopic cap. The delivery system was closed at neutral pH but opened at slightly acidic conditions due to the dissociation of T–Hg2+–T structures and the subsequent melting of dsDNA1. As proof-of-concept, doxorubicin (Dox) was loaded into the dsDNA1-modified MSN (MSN-dsDNA1) as a model drug. Controlled-release studies in water showed that no Dox leaked when the cap was closed and that release occurred immediately after acidification. By alternately changing the pH from 5.0 to 7.2, the DNA cap could be switched “on” and “off”, thereby regulating the partial release of Dox. Further in vitro studies demonstrated that the Dox-loaded MSN-dsDNA1 (MSN-Dox-dsDNA1) could be endocytosed and accumulated within lysosomes, followed by serving as a carrier for the controlled release of Dox into cell nuclei at the lysosomal pH level inside living cells. The cell viability results showed that the inhibitory concentration (IC50) of MSN-Dox-dsDNA1 was low (≈12.5 μg mL−1), while the IC50 of MSN-dsDNA1 (>100 μg mL−1) exceeded eight times higher than that of MSN-Dox-dsDNA1, indicating that MSN-dsDNA1 was fairly biocompatible and indeed served as a drug-carrier for intracellular controlled release. We believe that further developments of this acid-responsive drug-carrier will provide a promising nanodevice for in vivo delivery of therapeutic agents.

We reported a novel reversible stimuli-responsive controlled-release system consisting of mesoporous silica nanoparticles (MSN) functionalized with a smart DNA molecule-gated switch. In this system, a unique sequential cytosine (C)-rich DNA as the smart molecule-gated switch was grafted on the mesoporous silica nanoparticles (MSN) surface. In the presence of Ag+ ions, the closer C-rich DNA could hybridize each other by the formation of C–Ag+–C structure based on metal-dependent pairs of two nucleobases, resulting in blocking of pores and packing of guest molecules. By a competitive displacement reaction, the duplex DNA with C–Ag+–C structure deformed into single-stranded DNA in the presence of thiol-containing molecules, such as dithiothreitol (DTT), which gave rise to uncapping and the subsequent release of the entrapped guest molecules. The reversible open and closed states of the DNA molecule-gated switch could be easily achieved by alternating addition of Ag+ linkers and DTT molecules. Our results demonstrated that the system had excellent loading amount (43 μmol g−1) and good controlled release behavior. Moreover, the system could enter the cells through endocytosis and showed a low cytotoxicity even with treatment at a high concentration (200 μg mL−1). We believe that the stimuli-responsive controlled MSN release system based on the smart molecule-gated switch could play an important role in the development intracellular delivery nanodevices.