The trajectory tracking control problem for wheeled mobile robot (WMR) subject to generalized torque constraints is studied in this paper. First, a more general model is obtained by taking the ...displacement between the centre of mass of the WMR and the midpoint of the driving wheels into consideration. Then, a virtual velocity controller and a generalized torque controller are designed based on a new Lyapunov function. Due to the advantages of the new Lyapunov function, the stability of the trajectory tracking error system can be derived directly and the constraint of the initial tracking errors is removed. Less conservative conditions for tuning the controller parameters to satisfy the saturation constraints are also derived. Finally, some numerical examples are given to show the effectiveness of the proposed controllers.
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•Four homologous luminogens with AIE characteristics through acceptor substitution engineering were developed.•The four photosensitizers showed excellent ROS generation capacities and ...different organelle targeting abilities.•TBVP targeting cellular membrane exhibited the strongest antitumor PDT efficiency.
Photodynamic therapy (PDT) is a promising noninvasive treatment for cancer. Researchers have focused on improving the therapeutic effects of PDT in recent years. Subcellular organelles are the building blocks of cells, and their destruction can lead to cell dysfunction or even death. Photosensitizers (PSs) with precise organelle targeting capacity can not only kill cancer cells effectively but also help reduce PS dose, minimize side effects, and avoid drug resistance. Herein, four homologous luminogens with aggregation-induced emission (AIE) characteristics through acceptor substitution engineering are designed and synthesized to specifically anchor to mitochondria, cell membrane and lysosome through slight structural tweaks, and reactive oxygen species (ROS) are efficiently produced under light irradiation, which significantly enhance the therapy efficacy of PDT. Notably, biological studies have shown that membrane-targeted PS, TBVP exhibits more powerful therapeutic effects than other three PSs (TBPy, TBPy-Bu and TBPy-TA) at the same concentration. The highly effective anti-tumor activity of TBVP was evaluated successfully in vitro and in vivo. In addition, TBVP can promote cell autophagy to induce cell death. We thus believe the anchoring organelles approach described here represents an attractive therapeutic approach in photodynamic therapy.
The minimum void ratio is a fundamental physical index for evaluating particle properties in soil mechanics, ceramic processing, and concrete mixes. Previous research found that both particle size ...distribution and particle shape characteristics would affect minimum void ratio, while the current research generally uses a linear model to estimate the minimum void ratio of a binary mixture, ignoring quantitative effect of particle shape on the minimum void ratio. Based on a study of binary mixtures of natural sand from three different origins and iron particles of two different shapes, this paper analyzes the influence factors of the minimum void ratio, and a quadratic nonlinear model is proposed for estimating the minimum void ratio of binary mixture. The model contains only one undetermined coefficient, a, the value of which is correlated to the particle sphericity, particle size, and particle size ratio. A theoretical calculation formula for the coefficient a is proposed to quantitatively analyze the effects of these three factors on the size of the parameters. In the end, the model is used to estimate the minimum void ratios of sand and substitute particles from different producing areas; the average difference between the estimated values and the fitted values is about 2.03%, suggesting that the estimated values of the model fit well with the measured data.
Natural soiling of photovoltaic (PV) panel is an increasing problem especially in arid and desert areas. Finding a strategy that can reduce dust adhesion on PV panels is highly desirable but remains ...challenging. In this paper, different wettability of transparent coatings including superhydrophilic, hydrophilic, hydrophobic and superhydrophobic coatings were prepared to investigate the importance of surface roughness and surface energy. Their anti-soiling effects were investigated under different airflow velocity and different tilt angles. Dust deposition density, reduced transmittance, the ratio of reduced transmittance between bare glass surfaces and coatings, and PV efficiency reduction were used to characterize dust resistance performances. It is found that dust adhesion on superhydrophilic coatings was eminently governed by their respective high surface energy, with surface roughness rendering lesser contribution towards resisting/adhering effects. However, for other three coatings, further reducing the surface energy had little influence on the improvement of dust-proof ability. A large airflow velocity is beneficial to resist dust adhesion for all four types of coatings. However, a large airflow velocity has a limited ability to improve the anti-soiling effect of superhydrophilic coating under different tilt angles compared with other three coatings. The anti-soiling coatings can be referred to hydrophilic and hydrophobic coatings, not limited to superhydrophobic coating only. The study provides an invaluable guiding significance for preparation of dust-resistant coatings.
•The anti-soiling effects of different wettability of transparent coatings were investigated.•The anti-soiling effects were investigated under different airflow velocity and tilt angle.•Large airflow velocity was beneficial to resist dust adhesion for all four types of coatings.•The anti-soiling effect of superhydrophilic coating was the weakest under different tilt angles.•Surface roughness and surface energy both rendered contribution towards anti-soiling.
Friction and lubrication are ubiquitous in all kinds of movements and play a vital role in the smooth operation of production machinery. Water is indispensable both in the lubrication systems of ...natural organisms and in hydration lubrication systems. There exists a high degree of similarity between these systems, which has driven the development of hydration lubrication from biomimetic to artificial manufacturing. In particular, significant advancements have been made in the understanding of the mechanisms of hydration lubrication over the past 30 years. This enhanced understanding has further stimulated the exploration of biomimetic inspiration from natural hydration lubrication systems, to develop novel artificial hydration lubrication systems that are cost-effective, easily transportable, and possess excellent capability. This review summarizes the recent experimental and theoretical advances in the understanding of hydration-lubrication processes. The entire paper is divided into three parts. Firstly, surface interactions relevant to hydration lubrication are discussed, encompassing topics such as hydrogen bonding, hydration layer, electric double layer force, hydration force, and Stribeck curve. The second part begins with an introduction to articular cartilage in biomaterial lubrication, discussing its compositional structure and lubrication mechanisms. Subsequently, three major categories of bio-inspired artificial manufacturing lubricating material systems are presented, including hydrogels, polymer brushes (e.g., neutral, positive, negative and zwitterionic brushes), hydration lubricant additives (e.g., nano-particles, polymers, ionic liquids), and their related lubrication mechanism is also described. Finally, the challenges and perspectives for hydration lubrication research and materials development are presented.
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•The foundational theories of water-based lubrication have been reviewed comprehensively.•The latest advancements in bio-inspired artificial water-based lubrication systems were introduced.•Three major artificial water-based lubrication systems and their associated properties were summarized.•The development and innovation of strategies for manufacturing artificial water-based lubrication were discussed.
Photodynamic therapy (PDT) is a promising treatment for cancer, but still faces challenges. For example, the residual photosensitizers (PSs) can cause toxic effects on normal tissues. Thus, it is of ...great importance to change the PS into safe compounds in or after PDT process. In this work, a novel PS NTPy was synthesized and successfully applied for cancer therapy. NTPy with aggregation-induced emission (AIE) characteristics shows high reactive oxygen species generation efficiency and exhibits a strong fluorescence emission in 678 nm. In addition, NTPy shows excellent mitochondria targeting capacity. In hypoxic microenvironment, NTPy is degraded into TPyvia the reduction caused by nitroreductase. TPy shows very little PDT activities and low fluorescence emission. Therefore, NTPy can detect the hypoxic microenvironment of tumor through fluorescence “turn-off” response. More importantly, NTPy can reduce the side effects of PS on normal tissues after effective PDT treatment. This work provides a new strategy for intelligent PDT treatment and increases the biological safety of PDT.
•A new aggregation-induced emission (AIE) photosensitizer NTPy was developed.•NTPy showed excellent mitochondria targeting and high ROS generation capacities.•NTPy could be degraded into TPyvia the reduction by NTR in hypoxic condition.•TPy showed very little PDT activity and low fluorescence emission.
•Five new dithienopyrrolobenzothiadiazole-based organic dyes are reported.•DTPBT is used as donor for organic sensitizer for the first time.•W3 with phenothiazine shows better ability of suppressing ...electron recombination.•W5 sensitized DSSC achieves an efficiency of 7.98%.
Five new dithienopyrrolobenzothiadiazole (DTPBT)-based organic sensitizers were prepared for dye-sensitized solar cells (DSSCs). In this work, DTPBT unit was used as a donor to construct mono- and di-anchored metal-free organic sensitizers for the first time. The DTPBT unit applied as a donor or a π-spacer in mono-anchored dyes (W1 and W2) greatly influences the absorption range, HOMO-LUMO energy level and the solar cell performance of the dyes. The results show that the DTPBT unit is more suitable for acting as a π-spacer in D-π-A dyes. Di-anchored dyes exhibit broader photo-spectra response and higher molar extinction coefficients than those of the mono-anchored dyes. Di-anchored dyes W4 and W5 with DTPBT as the donor, thiophene as the π-bridge achieve high power conversion efficiencies of 7.93%, 7.98% with 1 mM CDCA as the co-adsorbent, respectively. The results suggest that the DTPBT moiety is a promising donor candidate to develop efficient double anchored organic dyes for DSSCs.
The acid sites of zeolite are important local structures to control the products in the chemical conversion. However, it remains a great challenge to precisely design the structures of acid sites, ...since there are still lack the controllable methods to generate and identify them with a high resolution. Here, we use the lattice mismatch of the intergrown zeolite to enrich the inherent Lewis acid sites (LASs) at the interface of a mortise-tenon ZSM-5 catalyst (ZSM-5-MT) with a 90° intergrowth structure. ZSM-5-MT is formed by two perpendicular blocks that are atomically resolved by integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM). It can be revealed by various methods that novel framework-associated Al (Al
) LASs are generated in ZSM-5-MT. Combining the iDPC-STEM results with other characterizations, we demonstrate that the partial missing of O atoms at interfaces results in the formation of inherent Al
LASs in ZSM-5-MT. As a result, the ZSM-5-MT catalyst shows a higher selectivity of propylene and butene than the single-crystal ZSM-5 in the steady conversion of methanol. These results provide an efficient strategy to design the Lewis acidity in zeolite catalysts for tailored functions via interface engineering.
Cardiovascular diseases (CVDs) are the leading cause of death worldwide, causing approximately 17.9 million deaths annually, an estimated 31% of all deaths, according to the WHO. CVDs are essentially ...rooted in atherosclerosis and are clinically classified into coronary heart disease, stroke and peripheral vascular disorders. Current clinical interventions include early diagnosis, the insertion of stents, and long-term preventive therapy. However, clinical diagnostic and therapeutic tools are subject to a number of limitations including, but not limited to, potential toxicity induced by contrast agents and unexpected bleeding caused by anti-platelet drugs. Nanomedicine has achieved great advancements in biomedical area. Among them, cell membrane coated nanoparticles, denoted as CMCNPs, have acquired enormous expectations due to their biomimetic properties. Such membrane coating technology not only helps avoid immune clearance, but also endows nanoparticles with diverse cellular and functional mimicry. In this review, we will describe the superiorities of CMCNPs in treating cardiovascular diseases and their potentials in optimizing current clinical managements.
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