Engineering van der Waals Materials for Advanced Metaphotonics.

The outstanding chemical and physical properties of 2D materials, together with their atomically thin nature, make them ideal candidates for metaphotonic device integration and construction, which requires deep subwavelength light-matter interaction to achieve optical functionalities beyond conventional optical phenomena observed in naturally available materials. In addition to their intrinsic properties, the possibility to further manipulate the properties of 2D materials via chemical or physical engineering dramatically enhances their capability, evoking new science on light-matter interaction, leading to leaped performance of existing functional devices and giving birth to new metaphotonic devices that were unattainable previously. Comprehensive understanding of the intrinsic properties of 2D materials, approaches and capabilities for chemical and physical engineering methods, the resulting property modifications and novel functionalities, and applications of metaphotonic devices are provided in this review. Through reviewing the detailed progress in each aspect and the state-of-the-art achievement, insightful analyses of the outstanding challenges and future directions are elucidated in this cross-disciplinary comprehensive review with the aim to provide an overall development picture in the field of 2D material metaphotonics and promote rapid progress in this fast emerging and prosperous field.

Can thick metal-halide perovskite single crystals have narrower optical bandgaps with near-infrared absorption?

Metal-halide perovskite (MHP) single crystals are emerging as potential competitors to their polycrystalline thin-film counterparts. These materials have shown the specific feature of extended absorbance towards the near-infrared (NIR) region, which promises further extension of their applications in the field of photovoltaics and photodetectors. This notable expansion of absorbance has been explained by the narrower effective optical bandgap of MHP single crystals promoted by their large thickness over several micrometres to millimetres. Herein, the attributes of the material's thickness and the measurement technique used to estimate these characteristics are discussed to elucidate the actual origins of the extended absorbance of MHP single crystals. Contrary to the general belief of the narrower bandgap of the MHP single crystals, we demonstrate that the extended NIR absorption in the MHP single crystals mainly originates from the combination of unique below-bandgap absorption of MHPs, the thickness of single crystals, and the technical limitation of the spectrophotometer, with the key attributes of (i) significantly large thickness of the MHP single crystals by suppressing the transmitted light and (ii) the detector's limited dynamic range. Combining the theoretical and experimental characterizations, we clarify the significant role of the large thickness together with the limited sensitivity of the detector in promoting the well-known red shift of the absorption onset of the MHP single crystals. The observations evidently show that in some special circumstances, the acquired absorption spectrum cannot reliably represent the optical bandgap of MHP materials. This highlights some misinterpretations in the estimation of the narrower optical bandgap of the MHP single crystals from conventional optical methods, while the optical bandgap is an inherent property independent of the thickness. The proposed broad applications of the MHP single crystals are dictated by their fascinating properties, and therefore, a deep insight into these features should be considered besides device applications, because much of their property-function relationships are still ambiguous and a subject of debate.

Synthesis of Layered Lead-Free Perovskite Nanocrystals with Precise Size and Shape Control and Their Photocatalytic Activity.

Halide perovskites have attracted enormous attention due to their potential applications in optoelectronics and photocatalysis. However, concerns over their instability, toxicity, and unsatisfactory efficiency have necessitated the development of lead-free all-inorganic halide perovskites. A major challenge in designing efficient halide perovskites for practical applications is the lack of effective methods for producing nanocrystals with precise size and shape control. In this work, a layered perovskite, Cs4ZnSb2Cl12 (CZS), is found from calculations to exhibit size- and facet-dependent optoelectronic properties in the nanoscale, and thus, a colloidal method is used to synthesize the CZS nanoparticles with size-tunable morphologies: zero- (nanodots), one- (nanowires and nanorods), two- (nanoplates), and three-dimensional (nanopolyhedra). The growth kinetics of the CZS nanostructures, along with the effects of surface ligands, reaction temperature, and time were investigated. The optoelectronic properties of the nanocrystals varied with size due to quantum confinement effects and with shape due to anisotropy within the crystals and the exposure of specific facets. These properties could be modulated to enhance the visible-light photocatalytic performance for toluene oxidation. In particular, the 9.7 nm CZS nanoplates displayed a toluene to benzaldehyde conversion rate of 1893 µmol g-1 h-1 (95% selectivity), 500 times higher than the bulk synthesized CZS, and comparable with the reported photocatalysts. This study demonstrates the integration of theoretical calculations and synthesis, revealing an approach to the design and fabrication of novel, high-performance colloidal perovskite nanocrystals for optoelectronic and photocatalytic applications.

Effective Suppressing Phase Segregation of Mixed-Halide Perovskite by Glassy Metal-Organic Frameworks.

Lead mixed-halide perovskites offer tunable bandgaps for optoelectronic applications, but illumination-induced phase segregation can quickly lead to changes in their crystal structure, bandgaps, and optoelectronic properties, especially for the Br-I mixed system because CsPbI3 tends to form a non-perovskite phase under ambient conditions. These behaviors can impact their performance in practical applications. By embedding such mixed-halide perovskites in a glassy metal-organic framework, a family of stable nanocomposites with tunable emission is created. Combining cathodoluminescence with elemental mapping under a transmission electron microscope, this research identifies a direct relationship between the halide composition and emission energy at the nanoscale. The composite effectively inhibits halide ion migration, and consequently, phase segregation even under high-energy illumination. The detailed mechanism, studied using a combination of spectroscopic characterizations and theoretical modeling, shows that the interfacial binding, instead of the nanoconfinement effect, is the main contributor to the inhibition of phase segregation. These findings pave the way to suppress the phase segregation in mixed-halide perovskites toward stable and high-performance optoelectronics.

Hit Identification Driven by Combining Artificial Intelligence and Computational Chemistry Methods: A PI5P4K-ß Case Study.

Computer-aided drug design (CADD), especially artificial intelligence-driven drug design (AIDD), is increasingly used in drug discovery. In this paper, a novel and efficient workflow for hit identification was developed within the ID4Inno drug discovery platform, featuring innovative artificial intelligence, high-accuracy computational chemistry, and high-performance cloud computing. The workflow was validated by discovering a few potent hit compounds (best IC50 is ∼0.80 µM) against PI5P4K-ß, a novel anti-cancer target. Furthermore, by applying the tools implemented in ID4Inno, we managed to optimize these hit compounds and finally obtained five hit series with different scaffolds, all of which showed high activity against PI5P4K-ß. These results demonstrate the effectiveness of ID4inno in driving hit identification based on artificial intelligence, computational chemistry, and cloud computing.

Rational Atom Substitution to Obtain Efficient, Lead-Free Photocatalytic Perovskites Assisted by Machine Learning and DFT Calculations.

Inorganic lead-free halide perovskites, devoid of toxic or rare elements, have garnered considerable attention as photocatalysts for pollution control, CO2 reduction and hydrogen production. In the extensive perovskite design space, factors like substitution or doping level profoundly impact their performance. To address this complexity, a synergistic combination of machine learning models and theoretical calculations were used to efficiently screen substitution elements that enhanced the photoactivity of substituted Cs2 AgBiBr6 perovskites. Machine learning models determined the importance of d10 orbitals, highlighting how substituent electron configuration affects electronic structure of Cs2 AgBiBr6 . Conspicuously, d10 -configured Zn2+ boosted the photoactivity of Cs2 AgBiBr6 . Experimental verification validated these model results, revealing a 13-fold increase in photocatalytic toluene conversion compared to the unsubstituted counterpart. This enhancement resulted from the small charge carrier effective mass, as well as the creation of shallow trap states, shifting the conduction band minimum, introducing electron-deficient Br, and altering the distance between the B-site cations d band centre and the halide anions p band centre, a parameter tuneable through d10 configuration substituents. This study exemplifies the application of computational modelling in photocatalyst design and elucidating structure-property relationships. It underscores the potential of synergistic integration of calculations, modelling, and experimental analysis across various applications.

Controllable Acceleration and Deceleration of Charge Carrier Transport in Metal-Halide Perovskite Single-Crystal by Cs-Cation Induced Bandgap Engineering.

Charge carrier transport in materials is of essential importance for photovoltaic and photonic applications. Here, the authors demonstrate a controllable acceleration or deceleration of charge carrier transport in specially structured metal-alloy perovskite (MACs)PbI3 (MA= CH3 NH3 ) single-crystals with a gradient composition of CsPbI3 /(MA1- x Csx )PbI3 /MAPbI3 . Depending on the Cs-cation distribution in the structure and therefore the energy band alignment, two different effects are demonstrated: i) significant acceleration of electron transport across the depth driven by the gradient band alignment and suppression of electron-hole recombination, benefiting for photovoltaic and detector applications; and ii) decelerated electron transport and thus improved radiative carrier recombination and emission efficiency, highly beneficial for light and display applications. At the same time, the top Cs-layer results in hole localization in the top layer and surface passivation. This controllable acceleration and deceleration of electron transport is critical for various applications in which efficient electron-hole separation and suppressed nonradiative electron-hole recombination is demanded.

Hexagonal metal oxide monolayers derived from the metal-gas interface.

Two-dimensional (2D) crystals are promising materials for developing future nano-enabled technologies1-6. The cleavage of weak, interlayer van der Waals bonds in layered bulk crystals enables the production of high-quality 2D, atomically thin monolayers7-10. Nonetheless, as earth-abundant compounds, metal oxides are rarely accessible as pure and fully stoichiometric monolayers owing to their ion-stabilized 'lamellar' bulk structure11-14. Here, we report the discovery of a layered planar hexagonal phase of oxides from elements across the transition metals, post-transition metals, lanthanides and metalloids, derived from strictly controlled oxidation at the metal-gas interface. The highly crystalline monolayers, without the support of ionic dopants or vacancies, can easily be mechanically exfoliated by stamping them onto substrates. Monolayer and few-layered hexagonal TiO2 are characterized as examples, showing p-type semiconducting properties with hole mobilities of up to 950 cm2 V-1 s-1 at room temperature. The strategy can be readily extended to a variety of elements, possibly expanding the exploration of metal oxides in the 2D quantum regime.

Manipulating the Fate of Charge Carriers with Tungsten Concentration: Enhancing Photoelectrochemical Water Oxidation of Bi2 WO6.

Bismuth tungstate (Bi2 WO6 ) thin film photoanode has exhibited an excellent photoelectrochemical (PEC) performance when the tungsten (W) concentration is increased during the fabrication. Plate-like Bi2 WO6 thin film with distinct particle sizes and surface area of different exposed facets are successfully prepared via hydrothermal reaction. The smaller particle size in conjunction with higher exposure extent of electron-dominated {010} crystal facet leads to a shorter electron transport pathway to the bulk surface, assuring a lower charge transfer resistance and thus minimal energy loss. In addition, it is proposed based on the results from conductive atomic force microscopy that higher W concentration plays a crucial role in facilitating the charge transport of the thin film. The "self-doped" of W in Bi2 WO6 will lead to the higher carrier density and improved conductivity. Thus, the variation in the W concentration during a synthesis can be served as a promising strategy for future W based photoanode design to achieve high photoactivity in water splitting application.

Extracellular α-Synuclein Modulates Iron Metabolism Related Proteins via Endoplasmic Reticulum Stress in MES23.5 Dopaminergic Cells.

Alpha-synuclein plays a vital role in the pathology of Parkinson's disease (PD). Spreading of α-synuclein in neighboring cells was believed to contribute to progression in PD. How α-synuclein transmission affects adjacent cells is not full elucidated. Here, we used recombinant α-synuclein to mimic intercellular transmitted α-synuclein in MES23.5 dopaminergic cells, to investigate whether and how it could modulate iron metabolism. The results showed that α-synuclein treatment up-regulated divalent metal transporter 1 (DMT1) and down-regulated iron transporter (FPN), also up-regulated iron regulatory protein 1 (IRP1) protein levels and hepcidin mRNA levels. Endocytosis inhibitor dynasore pretreatment completely abolished and even reversed the upregulation of DMT1 and IRP1 induced by α-synuclein, however, FPN down-regulation was partially blocked by dynasore. Autophagy-inducing agent rapamycin reversed DMT1 up-regulation and FPN down-regulation, and fully blocked the upregulation of IRP1. Elevated hepcidin levels induced by α-synuclein was fully blocked by dynasore pretreatment, however, even higher with rapamycin pretreatment. Alpha-synuclein treatment triggered endoplasmic reticulum (ER) stress. ER stress inducer thapsigargin induced similar responses elicited by α-synuclein. ER stress inhibitor salubrinal blocked the up-regulation of IRP1 and hepcidin, as well as DMT1 up-regulation and FPN down-regulation, also dramatically abolished cAMP-response elements binding protein phosphorylation induced by α-synuclein. Taken together, these finding indicated that extracellular α-synuclein could regulate cellular iron metabolism, probably mediated by ER stress. It provides novel evidence to elucidate the relationships between transmitted α-synuclein and iron metabolism disturbance in PD.

[Altered dopamine metabolism and its role in pathogenesis of Parkinson's disease].

Parkinson's disease (PD), one of the most frequent neurodegenerative disorders, is characterized by the selective loss of dopaminergic neurons in the substantia nigra (SN). Genetic vulnerability, aging, environmental insults are believed to contribute to the pathogenesis of PD. However, the cellular and molecular mechanism of dopaminergic neurons degeneration remains incompletely understood. Dopamine (DA) metabolism is a cardinal physiological process in dopaminergic neurons, which is closely related to the loss of dopaminergic neurons in the SN. DA metabolism takes part in several pathological processes of PD neurodegeneration, such as iron metabolism disturbance, α-synuclein mis-folding, endoplasmic reticulum stress, protein degradation dysfunction, neuroinflammatory response, etc. In this review, we will describe altered DA metabolism and its contributions to PD pathogenesis.

Metal-Organic Framework Decorated Cuprous Oxide Nanowires for Long-lived Charges Applied in Selective Photocatalytic CO2 Reduction to CH4.

Improving the stability of cuprous oxide (Cu2 O) is imperative to its practical applications in artificial photosynthesis. In this work, Cu2 O nanowires are encapsulated by metal-organic frameworks (MOFs) of Cu3 (BTC)2 (BTC=1,3,5-benzene tricarboxylate) using a surfactant-free method. Such MOFs not only suppress the water vapor-induced corrosion of Cu2 O but also facilitate charge separation and CO2 uptake, thus resulting in a nanocomposite representing 1.9 times improved activity and stability for selective photocatalytic CO2 reduction into CH4 under mild reaction conditions. Furthermore, direct transfer of photogenerated electrons from the conduction band of Cu2 O to the LUMO level of non-excited Cu3 (BTC)2 has been evidenced by time-resolved photoluminescence. This work proposes an effective strategy for CO2 conversion by a synergy of charge separation and CO2 adsorption, leading to the enhanced photocatalytic reaction when MOFs are integrated with metal oxide photocatalyst.

Association of PD-L1 expression status with the efficacy of PD-1/PD-L1 inhibitors and overall survival in solid tumours: A systematic review and meta-analysis.

Whether PD-L1-positive patients derive more overall survival benefit from PD-1/PD-L1 inhibitors in the treatment of advanced solid tumours is unclear. We systematically searched the PubMed, Cochrane library and EMBASE databases from January 1, 1966 to March 1, 2019, to identify randomised controlled trials of PD-1/PD-L1 inhibitors (nivolumab, pembrolizumab, atezolizumab, durvalumab and avelumab) that had available hazard ratios (HRs) for death according to PD-L1 status. A random-effects model was used to calculate the pooled overall survival (OS) HR and 95% CI among PD-L1-positive and PD-L1-negative patients. An interaction test was performed to evaluate the heterogeneity between the two estimates. A total of 24 randomised trials, involving 12,966 participants, fulfilled the inclusion criteria. An OS benefit of PD-1/PD-L1 inhibitors was found in both PD-L1-positive patients (HR, 0.65; 95% CI, 0.60-0.70) and PD-L1-negative patients (HR, 0.82; 95% CI, 0.74-0.91) even at the minimum cut-off value of 1%. Significant differences in the efficacy of PD-1/PD-L1 inhibitors between PD-L1-positive and PD-L1-negative patients were noted at different cut-off values. Moreover, there was a positive dose-response relationship between PD-L1 positivity and OS benefit (HR for 1%, 0.58, [0.50, 0.67]; 5%, 0.52 [0.43, 0.64]; 10%, 0.50 [0.40, 0.63]). Subgroup analyses showed that these results were generally consistent, regardless of study design, line of treatment, treatment type, tumour type, PD-L1 staining cell type and median follow-up time. We demonstrated that PD-1/PD-L1 inhibitors significantly improved OS in both PD-L1 positive and PD-L1 negative patients compared to controls, but the magnitude of benefit was clinically PD-L1-dependent.

A case report of Proteus syndrome (PS).

BACKGROUND: Proteus syndrome (PS) is an extremely rare disease characterized by excessive chimeric growth of cells, and progressive and irregular asymmetrical hyperplasia. CASE PRESENTATION: Herein, a PS case with atypical clinical features and syndromes was reported, to improve the understanding of the diagnosis and treatment of the disease. The case was a 3-year-and-11-month-old male child. He was admitted due to a primary diagnosis of McCune-Albright syndrome. After admission, the lesion samples from the milk coffee spots, and nodular thickening skin at hands and feet were subjected to genetic screening. Genetic testing results confirmed the diagnosis of PS. CONCLUSIONS: Based on the clinical manifestations, laboratory tests, imaging data, and literature reviewing, the etiology, diagnosis, treatment and prognosis of PS have been analyzed and discussed.

The prognostic value of PKM2 and its correlation with tumour cell PD-L1 in lung adenocarcinoma.

BACKGROUND: The prognostic value of PKM2 and its correlation with tumour cell PD-L1 in lung adenocarcinoma (LUAD) is unclear. METHODS: A total of 506 lung adenocarcinoma samples from The Cancer Genome Atlas (TCGA) dataset and 173 LUAD tumour tissues from Jiangxi Cancer Hospital were used to analyse the correlation between PKM2 and PD-L1 expression. We further established a stable LUAD cell line with PKM2 knockdown and confirmed the association via Western blotting and flow cytometry analysis. Moreover, the prognostic values of PKM2 and PD-L1 were evaluated by the Kaplan-Meier method and Cox proportional hazards models. RESULTS: Based on the above two large cohorts, we found that PKM2 was significantly positively associated with PD-L1 expression (r = 0.132, P = 0.003 and r = 0.287, P < 0.001, respectively). Subsequently, we found that PKM2 knockdown substantially inhibited PD-L1 expression in the A549 LUAD cell line. Moreover, survival analysis showed that higher expression of PKM2 was correlated with significantly shorter overall survival (OS) and disease-free survival (DFS) in lung adenocarcinoma patients (P < 0.001 and P = 0.050, respectively). Subgroup analysis showed that lung adenocarcinoma patients who expressed high PKM2 and PD-L1 levels experienced the poorest OS and DFS. Additionally, multivariate analysis suggested that high PKM2 and PD-L1 expression was an independent prognostic indicator for worse OS and DFS (HR = 1.462, P < 0.001 and HR = 1.436, P = 0.004, respectively). CONCLUSIONS: Our results demonstrated that PKM2 regulated PD-L1 expression and was associated with poor outcomes in lung adenocarcinoma patients.

Interfacing BiVO4 with Reduced Graphene Oxide for Enhanced Photoactivity: A Tale of Facet Dependence of Electron Shuttling.

Efficient interfacial charge transfer is essential in graphene-based semiconductors to realize their superior photoactivity. However, little is known about the factors (for example, semiconductor morphology) governing the charge interaction. Here, it is demonstrated that the electron transfer efficacy in reduced graphene oxide-bismuth oxide (RGO/BiVO4 ) composite is improved as the relative exposure extent of {010}/{110} facets on BiVO4 increases, indicated by the greater extent of photocurrent enhancement. The dependence of charge transfer ability on the exposure degree of {010} relative to {110} is revealed to arise due to the difference in electronic structures of the graphene/BiVO4 {010} and graphene/BiVO4 {110} interfaces, as evidenced by the density functional theory calculations. The former interface is found to be metallic with higher binding energy and smaller Schottky barrier than that of the latter semiconducting interface. The facet-dependent charge interaction elucidated in this study provides new aspect for design of graphene-based semiconductor photocatalyst useful in manifold applications.

Mobile Charge-Induced Fluorescence Intermittency in Methylammonium Lead Bromide Perovskite.

Organic-inorganic halide perovskite has emerged as a very promising material for solar cells due to its excellent photovoltaic enabling properties resulting in rapid increase in device efficiency over the last 3 years. Extensive knowledge and in-depth physical understanding in the excited state carrier dynamics are urgently required. Here we investigate the fluorescence intermittency (also known as blinking) in vapor-assisted fabricated CH3NH3PbBr3 perovskite. The evident fluorescence blinking is observed in a dense CH3NH3PbBr3 perovskite film that is composed of nanoparticles in close contact with each other. In the case of an isolated nanoparticle no fluorescence blinking is observed. The "ON" probability of fluorescence is dependent on the excitation intensity and exhibits a similar power rule to semiconductor quantum dots at higher excitation intensity. As the vapor-assisted fabricated CH3NH3PbBr3 perovskite film is a cluster of nanoparticles forming a dense film, it facilitates mobile charge migration between the nanoparticles and charge accumulation at the surface or at the boundary of the nanoparticles. This leads to enhanced Auger-like nonradiative recombination contributing to the fluorescence intermittency observed. This finding provides unique insight into the charge accumulation and migration and thus is of crucial importance for device design and improvement.

Effect of Blend Composition on Binary Organic Solar Cells Using a Low Band Gap Polymer.

This report investigates the influence of the solution blend composition of binary bulk heterojunction organic solar cells composed of poly(2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H- cyclopenta[2,1-b:3,4-b'dithiophene-2,6-diy]] (PCPDTBT) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). The blend polymer:fullerene composition was varied from 1:1 (50 wt% PC71 BM) to 2:9 (82 wt% PC71 BM). Increasing the amount of polymer in the blend results in the greatest overall absorption, as the donor material PCPDTBT is the main contributor to absorption. However, high polymer content leads to poor photovoltaic performance. For this material combination, the optimum blend polymer:fullerene composition was found to be 2:7. Increasing the fullerene content in the blend led to a significant improvement in the internal quantum efficiency of devices. This was correlated with an increase of the electron mobility, as the fullerene content was increased. Improved electron transport, leading to more balanced transport between electrons and holes, significantly improved the short circuit current density (Jsc) and fill factor (FF).

Dynamic study on the transformation process of gold nanoclusters.

In this paper, the transformation process from Au8 to Au25 nanoclusters (NCs) is investigated with steady state fluorescence spectroscopy and time-resolved fluorescence spectroscopy at various reaction temperatures and solvent diffusivities. Results demonstrate that Au8 NCs, protected by bovine serum albumin, transform into Au25 NCs under controlled pH values through an endothermic reaction with the activation energy of 74 kJ mol(-1). Meanwhile, the characteristic s-shaped curves describing the formation of Au25 NCs suggest this process involves a diffusion controlled growth mechanism.

Inhibition of thioredoxin reductase and upregulation of apoptosis genes for effective anti-tumor sono-chemotherapy using a meso-organosilica nanomedicine.

The thioredoxin system is involved in cancer development and therefore is a promising target for cancer chemotherapy. Thioredoxin reductase (TrxR) is a key component of the thioredoxin (Trx) system, and is overexpressed in many cancers to inhibit apoptosis-related proteins. Alternatively, inhibition of thioredoxin reductase and upregulation of apoptosis factors provide a therapeutic strategy for anti-tumor treatment. In this study, an ultrasound-activatable meso-organosilica nanomedicine was prepared by integrating chloroquine (CQ) into hollow mesoporous organosilica (CQ@MOS). The meso-organosilica nanomedicine can inhibit the activity of thioredoxin reductase, elevate cellular reactive oxygen species (ROS) levels, upregulate the pro-apoptotic factors in the c-Jun N-terminal kinase (JNK) apoptosis pathway and induce autophagy inhibition, further resulting in mitochondrial membrane potential (MMP) depolarization and cellular ATP content decrease, ultimately causing significant damage to tumor cells. Moreover, CQ@MOS can efficiently deliver chloroquine into cancer cells and promote an enhanced sonodynamic effect for effective anti-tumor chemotherapy and sonodynamic therapy. This study may enlighten us on a new anti-tumor strategy and suggest its promising applications in cancer treatments.