Construction and Observation of Flexibly Controllable High-Dimensional Non-Hermitian Skin Effects.

Non-Hermitian skin effect (NHSE) is one of the most fundamental phenomena in non-Hermitian physics. It is established that 1D NHSE originates from the nontrivial spectral winding topology. However, the topological origin behind the higher-dimensional NHSE remains unclear, which poses a substantial challenge in constructing and manipulating high-dimensional NHSEs. Here, an intuitive bottom-to-top scheme to construct high-dimensional NHSEs is proposed, through assembling multiple independent 1D NHSEs. Not only the elusive high-dimensional NHSEs can be effectively predicted from the well-defined 1D spectral winding topologies, but also the high-dimensional generalized Brillouin zones can be directly synthesized from the 1D counterparts. As examples, two 2D nonreciprocal acoustic metamaterials are experimentally implemented to demonstrate highly controllable multi-polar NHSEs and hybrid skin-topological effects, where the sound fields can be frequency-selectively localized at any desired corners and boundaries. These results offer a practicable strategy for engineering high-dimensional NHSEs, which can boost advanced applications such as selective filters and directional amplifiers.

Flooding Performance and Optimization of Injection Parameters of Nanosized Oil Displacement Agents in Extra-Low-Permeability Reservoirs.

There have been few studies on the role of nanofluids in oil displacement and injection parameters, despite their significant impact on the oil displacement effect. To enhance oil recovery in an ultralow-permeability reservoir, the nanosized oil-displacement agent with nano-SiO2 modified by a silane coupling agent as a main component was selected for the first time in the Changqing oilfield. To assess the performance of the nanofluid, various factors such as particle size, contact angle, interfacial tension, and emulsion stability were taken into consideration. The oil displacement effect of nanofluids was evaluated by a microscopic model and ultralow-permeability core displacement experiment, and its optimal injection parameters were determined. The average particle size of the nano-oil displacement agent is 22-30 nm. It can change the wetting condition of the rock from oil-wet to water-wet and reduce the oil-water interfacial tension. Even at 80 °C, the emulsion formed by the agent remained stable. The oil displacement experiment shows that the nano-oil displacement agent whose injection pressure increases can displace the residual oil trapped in small pores that cannot be affected by conventional water flooding. The injection mode of "nanoflooding agent drive + water drive + nanoflooding agent drive", injection rate of 0.1 mL/min, injection concentration of 0.5%, and injection volume of 0.5 PV (0.25 PV per segment), which can effectively guide the injection of the oil displacement agent, achieve the best oil displacement effect.

An Efficient Self-Powered Seawater Desalination System Based on a Wind-Driven Radial-Arrayed Rotary Triboelectric Nanogenerator.

Seawater desalination (SD) is regarded as one of the most effective solutions to the shortage of fresh water in many desert and island areas. However, high energy consumption and environmental pollution impede its development. Herein, a self-powered seawater desalination (SP-SD) system is proposed to reduce energy consumption and environmental pollution by using a wind-driven radial-arrayed rotary triboelectric nanogenerator (RAR-TENG). As expected, the SP-SD unit achieves a high desalination capacity of 10.5 mg/h for the 0.17 M NaCl solution at a rotation speed of 350 rpm with a hydrogen (H2) production rate of 5.6 × 10-4 mL/s, which is superior to most previous reported results. Moreover, the SP-SD system could easily reach a desalination capacity of 2.4 mg/h at a low wind speed of 6 m/s by using natural wind energy. This wind-driven SP-SD system contributes an innovative approach to the field of environmental electrochemistry.

Cobalt-Doped Carbon Quantum Dots with Peroxidase-Mimetic Activity for Ascorbic Acid Detection through Both Fluorometric and Colorimetric Methods.

In this work, we fabricated cobalt-doped carbon quantum dots (Co-CQDs) by a one-pot hydrothermal method with cobalt tetraphenylporphyrin and 1,2-ethanediamine as precursors. The morphology and structure of the Co-CQDs were characterized through transmission electron microscopy, X-ray diffraction spectra, Fourier transform infrared, and X-ray photoelectron spectra. The Co-CQDs emitted intense blue luminescence under ultraviolet irradiation and exhibited a typical excitation-dependent emission property. Moreover, they can act as a fluorescent probe for the detection of Fe3+ and ascorbic acid (AA) with high selectivity and sensitivity through an "on-off-on" mode. The limit of detection (LOD) of Fe3+ was measured as 38 µM (S/N = 3). The quenched emission of carbon quantum dots can be recovered with the addition of ascorbic acid (AA) to the Co-CQDs/Fe3+ system. The change of fluorescence was linear with the concentration of AA (0.6-1.6 mM) with the LOD of 18 µM. Furthermore, the Co-CQDs exhibited high oxidase-like catalytic behavior, which could convert transparent 3,3',5,5'-tetramethylbenzidine (TMB) into blue ox-TMB by dissolved oxygen. After adding ascorbic acid to the Co-CQDs/TMB system, the blue color of the solution faded due to the reduction of blue ox-TMB to colorless TMB. Based on this phenomenon, the Co-CQDs were capable of detecting AA (10-400 µM) with the LOD of 0.27 µM. The fluorometric and colorimetric assays based on the Co-CQDs for the AA detection were then successfully applied in fresh fruits. Furthermore, the high biocompatibility of the Co-CQDs against HeLa cells was verified by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Thus, the Co-CQDs could be used as a powerful tool for the detection of AA in real samples through a dual-mode method.

Exploration of Novel Xanthine Oxidase Inhibitors Based on 1,6-Dihydropyrimidine-5-Carboxylic Acids by an Integrated in Silico Study.

Xanthine oxidase (XO) is an important target for the effective treatment of hyperuricemia-associated diseases. A series of novel 2-substituted 6-oxo-1,6-dihydropyrimidine-5-carboxylic acids (ODCs) as XO inhibitors (XOIs) with remarkable activities have been reported recently. To better understand the key pharmacological characteristics of these XOIs and explore more hit compounds, in the present study, the three-dimensional quantitative structure-activity relationship (3D-QSAR), molecular docking, pharmacophore modeling, and molecular dynamics (MD) studies were performed on 46 ODCs. The constructed 3D-QSAR models exhibited reliable predictability with satisfactory validation parameters, including q2 = 0.897, R2 = 0.983, rpred2 = 0.948 in a CoMFA model, and q2 = 0.922, R2 = 0.990, rpred2 = 0.840 in a CoMSIA model. Docking and MD simulations further gave insights into the binding modes of these ODCs with the XO protein. The results indicated that key residues Glu802, Arg880, Asn768, Thr1010, Phe914, and Phe1009 could interact with ODCs by hydrogen bonds, π-π stackings, or hydrophobic interactions, which might be significant for the activity of these XOIs. Four potential hits were virtually screened out using the constructed pharmacophore model in combination with molecular dockings and ADME predictions. The four hits were also found to be relatively stable in the binding pocket by MD simulations. The results in this study might provide effective information for the design and development of novel XOIs.

1T-Phase Dirac Semimetal PdTe2 Nanoparticles for Efficient Photothermal Therapy in the NIR-II Biowindow.

1T-phase transition-metal dichalcogenides (TMDs) nanomaterials are one type of emerging and promising near-infrared II (NIR-II) photothermal agents (PTAs) derived from their distinct metallic electronic structure, but it is still challenging to synthesize these nanomaterials. Herein, PdTe2 nanoparticles (PTNs) with a 1T crystal symmetry and around 50 nm in size are prepared by an electrochemical exfoliation method, and the corresponding photothermal performances irradiated under a NIR-II laser have been explored. The encapsulation of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG) endows PTNs with water solubility, enhanced photothermal stability, and high biocompatibility. Notably, PTN/DSPE-PEG displays a potent absorbance through the NIR-II zone and considerable photothermal conversion efficiency, which is up to 68% when irradiated with a 1060 nm laser. With these unique photothermal properties, excellent in vitro and in vivo tumor inhibition effects of PTN/DSPE-PEG have been achieved under the irradiation of a NIR-II (1060 nm) laser without visible toxicity to normal tissues, suggesting that it is an efficient NIR-II photothermal nanoagent.

Facile Coordination-Precipitation Route to Insoluble Metal Roussin's Black Salts for NIR-Responsive Release of NO for Anti-Metastasis.

A facile and general coordination-precipitation method is developed to synthesize insoluble metal Roussin's black salts (Me-RBSs) as a new type of NIR-responsive NORMs. The weak-field ligand coordination of metal+-RBS- brings a NIR absorption effect of Me-RBSs, and further gives rise to the NIR adsorption-dependent NIR-responsive NO release profile. Intratumoral NIR-responsive release of NO effectively inhibits the growth and metastasis of the metastatic breast cancer. Aqueous insolubility of Me-RBSs ensures lower cytotoxicity and higher thermostability compared with traditional soluble RBSs. This work establishes a new class of NIR-sensitive NO donors, and may spark new inspiration for designing intelligent gas-releasing molecules.

Giant Gating Tunability of Optical Refractive Index in Transition Metal Dichalcogenide Monolayers.

We report that the refractive index of transition metal dichacolgenide (TMDC) monolayers, such as MoS2, WS2, and WSe2, can be substantially tuned by >60% in the imaginary part and >20% in the real part around exciton resonances using complementary metal-oxide-semiconductor (CMOS) compatible electrical gating. This giant tunablility is rooted in the dominance of excitonic effects in the refractive index of the monolayers and the strong susceptibility of the excitons to the influence of injected charge carriers. The tunability mainly results from the effects of injected charge carriers to broaden the spectral width of excitonic interband transitions and to facilitate the interconversion of neutral and charged excitons. The other effects of the injected charge carriers, such as renormalizing bandgap and changing exciton binding energy, only play negligible roles. We also demonstrate that the atomically thin monolayers, when combined with photonic structures, can enable the efficiencies of optical absorption (reflection) tuned from 40% (60%) to 80% (20%) due to the giant tunability of the refractive index. This work may pave the way toward the development of field-effect photonics in which the optical functionality can be controlled with CMOS circuits.

Intratumoral H2O2-triggered release of CO from a metal carbonyl-based nanomedicine for efficient CO therapy.

A new H2O2-responsive nanomedicine for CO therapy is constructed by effectively encapsulating the hydrophobic manganese carbonyl prodrug into an advanced hollow mesoporous silica nanoparticle carrier to realize the intratumoral H2O2-triggered release of CO and selective killing of tumour cells rather than normal cells, exhibiting high in vitro and in vivo efficacies of CO therapy.