Two-dimensional optical coherence tomography for real-time structural dynamical characterization

We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.     

Broadband high-efficiency controllable asymmetric propagation by pentamode acoustic metasurface

We utilise the pentamode metasurface to realise broadband high-efficiency and controllable asymmetric transmission. The designed metasurface can manipulate the acoustic waves, as expected from the generalised Snell's law, and exhibits unique characteristics such as extraordinary broadband acoustic control, apparent negative refraction, and conversion from the propagating wave to surface mode. The asymmetric transmission features of positive refraction for the forward incidence (FI) and negative refraction for the reverse incidence (RI) can be realised within the range of 2600 Hz to 5600 Hz by controlling the incident angle from 0° to 35° with the transmission efficiency higher than 85.4% for the FI and RI. In addition, by further adjusting the angle of incidence in the range of 25° to 90°, asymmetric transmission characteristics can be expressed as surface wave transmission for the FI and transmitted wave transmission for the RI within the same frequency ranges.     

Numerical solution of bed load transport equations using discrete least squares meshless (DLSM) method

The discrete least squares meshless (DLSM) method is extended in this paper for solving coupled bedload sediment transport equations. The mathematical formulation of this model consists of shallow water equations for the hydrodynamical component and an Exner equation expressing sediment continuity for the bedload transport. This method uses the moving least squares (MLS) function approximation to construct the shape functions and the minimizing least squares functional method to discretize the system of equations. The method can be viewed as a truly meshless method as it does not need any mesh for both field variable approximation and the construction of system matrices; it also provides the symmetric coefficient matrix. In the present work, several benchmark problems are studied and compared with the work of other researchers; the proposed method shows good accuracy, high convergence rate, and high efficiency, even for irregularly distributed nodes. At the end, a real test problem is performed to show and verify the main benefit and applicability of the proposed method to cope with complex geometry in practical problems.     

Unravelling the Enigma of Nonoxidative Conversion of Methane on Iron Single-Atom Catalysts

The direct, nonoxidative conversion of methane on a silica-confined single-atom iron catalyst is a landmark discovery in catalysis, but the proposed gas-phase reaction mechanism is still open to discussion. Here, we report a surface reaction mechanism by computational modeling and simulations. The activation of methane occurs at the single iron site, whereas the dissociated methyl disfavors desorption into gas phase under the reactive conditions. In contrast, the dissociated methyl prefers transferring to adjacent carbon sites of the active center (Fe₁©SiC₂), followed by C−C coupling and hydrogen transfer to produce the main product (ethylene) via a key −CH−CH₂ intermediate. We find a quasi Mars–van Krevelen (quasi-MvK) surface reaction mechanism involving extracting and refilling the surface carbon atoms for the nonoxidative conversion of methane on Fe₁©SiO₂ and this surface process is identified to be more plausible than the alternative gas-phase reaction mechanism.     

First-Principles Investigation of β-FeOOH for Hydrogen Evolution: Identifying Reactive Sites and Boosting Surface Reactions

Akaganeite (β-FeOOH) is a widely investigated candidate for photo(electro)catalysis, such as water splitting. Nevertheless, insights into understanding the surface reaction between water and β-FeOOH, in particular, the hydrogen evolution reaction (HER), are still insufficient. Herein, a set of first-principles calculations on pristine β-FeOOH and halogen-substituted β-FeOOH are applied to evaluate the HER performance through the computational hydrogen electrode model. The results show that the HER on β-FeOOH tends to occur at Fe sites on the (010) surface, and palladium and nickel are found to serve as excellent co-catalysts to boost the HER process, due to the remarkably reduced free energy change of hydrogen adsorption upon loading on the surface of β-FeOOH, demonstrating great potential for efficient water splitting.     

Modeling and character analyzing of multiple fractional-order memcapacitors in parallel connection

Recently,the memory elements-based circuits have been addressed frequently in the nonlinear circuit theory due to their unique behaviors.Thus,the modeling and characterizing of the mem-elements become essential.In this paper,the analysis of the multiple fractional-order voltage-controlled memcapacitors model in parallel connection is studied.Firstly,two fractional-order memcapacitors are connected in parallel,the equivalent model is derived,and the characteristic of the equivalent memcapacitor is analyzed in positive or negative connection.Then a new understanding manner according to different rate factor K and fractional orderαis derived to explain the equivalent modeling structure conveniently.Additionally,the negative order appears,which is a consequence of the combination of memcapacitors in different directions.Meanwhile,the equivalent parallel memcapacitance has been drawn to determine that multiple fractional-order memcapacitors could be calculated as one composite memcapacitor.Thus,an arbitrary fractional-order equivalent memcapacitor could be constructed by multiple fractional-order memcapacitors.     

Degradable nanocatalyst enables antitumor/antibacterial therapy and promotion of wound healing for diabetes via self-enhanced cascading reaction

Diabetic patients often have problems such as residual tumor and wound infection after tumor resection, causing severe clinical problems. It is urgent to develop effective therapies to reach oncotherapy/anti-infection/promotion of wound healing combined treatment. Herein, we propose CS/MnO₂-GOx (CMGOx) nanocatalysts for the specific catalytic generation of ^•OH to inhibit tumors and bacteria in a hyperglycemic environment. The good biocompatible chitosan (CS), as a carrier for the catalyst, exhibits excellent antibacterial effect as well as promotes wound healing. Glucose oxidase (GOx) is loaded on the surface of CS nanoparticles to generate H₂O₂ and gluconic acid by consuming glucose (starvation therapy, ST) and O₂. The MnO₂ depletes glutathione (GSH) to produce Mn²⁺, amplifying oxidative stress and further promoting the activity of Mn²⁺-mediated Fenton-like reaction to produce ^•OH (chemodynamic therapy, CDT) in weak acidic environment. Moreover, the produced gluconic acid lowers the pH of the environment, enhancing chemodynamic therapy (ECDT). The tumor cells and bacteria are efficiently eliminated by the synergistic effect of ST and ECDT. The MnO₂ nanoparticles at neutral environment decomposes H₂O₂ into O₂, which cooperate with CS to promote healing. The self-enhanced cascade reaction of CMGOx in situ exhibits excellent effects of antitumor/antibacterial therapy and promotion of wound healing, offering a promising integrated treatment for diabetic patients after tumor surgical resection.     

Pan-cancer analysis of DNA epigenetic modifications by hydrophilic interaction liquid chromatography-tandem mass spectrometry

Accumulating evidence in recent years indicates that DNA methylation (5-methyl-2′-deoxycytidine, 5-mdC) and hydroxymethylation (5-hydroxymethyl-2′-deoxycytidine, 5-hmdC) have been implicated in various biological processes, and the aberrations of these DNA cytosine modifications is tightly associated with cancer. N⁶-methyl-2′-deoxyadenosine (m⁶dA), as a newly discovered epigenetic modification in genome of mammals, has been demonstrated to play vital regulatory roles in tumorigenesis. However, the content information of m⁶dA in human tumor tissues is still limited and pan-cancer analysis of these DNA epigenetic modifications is lacked. Herein, we developed a sensitive and robust stable isotope-diluted hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for accurate quantification of m⁶dA, 5-mdC and 5-hmdC in genomic DNA from 82 pairs of human tumor tissues and matched tumor-adjacent normal tissues. The types of tumors included esophagus cancer, lung cancer, breast cancer, liver cancer, pancreatic cancer, gastric cancer, stromal tumor and colorectal cancer. Compared to the normal tissues, we revealed the level of m⁶dA was increased in tumor tissues of esophagus cancer, lung cancer and liver cancer, whereas the level of m⁶dA was diminished in tumor tissues of pancreatic cancer and gastric cancer; while the contents of 5-mdC and 5-hmdC exhibited significant decrease in tumor tissues of most types of cancer. It is worth noting that we revealed, for the first time, the content of genomic m⁶dA in pancreatic cancer, stromal tumor and colorectal cancer. The significant changes of these DNA epigenetic modifications indicate they may serve as indicators of cancers. In addition, this study will benefit for better understanding of the regulatory roles of these DNA epigenetic modifications in cancers.