Rational Design and Precise Synthesis of Single-Atom Alloy Catalysts for the Selective Hydrogenation of Nitroarenes.

Single-atom alloys (SAAs) have gained increasing prominence in the field of selective hydrogenation reactions due to their uniform distribution of active sites and the unique host-guest metal interactions. Herein, 15 SAAs are constructed to comprehensively elucidate the relationship between host-guest metal interaction and catalytic performance in the selective hydrogenation of 4-nitrostyrene (4-NS) by density functional theory (DFT) calculations. The results demonstrate that the SAAs with strong host-guest metal interactions exhibit a preference for N─O bond cleavage, and the reaction energy barrier of the hydrogenation process is primarily influenced by the host metal. Among them, Ir1Ni SAA stands out as the prime catalyst candidate, showcasing exceptional activity and selectivity. Furthermore, the Ir1Ni SAA is subsequently prepared through precise synthesis techniques and evaluated in the selective hydrogenation of 4-NS to 4-aminostyrene (4-AS). As anticipated, the Ir1Ni SAA demonstrates extraordinary catalytic performance (yield > 96%). In situ FT-IR experiments and DFT calculations further confirmed that the unique host-guest metal interaction at the Ir-Ni interface site of Ir1Ni SAA endows it with excellent 4-NS selective hydrogenation ability. This work provides valuable insights into enhancing the performance of SAAs catalysts in selective hydrogenation reactions by modulating the host-guest metal interactions.

Pathology steered stratification network for subtype identification in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a heterogeneous, multifactorial neurodegenerative disorder characterized by three neurobiological factors beta-amyloid, pathologic tau, and neurodegeneration. There are no effective treatments for AD at a late stage, urging for early detection and prevention. However, existing statistical inference approaches in neuroimaging studies of AD subtype identification do not take into account the pathological domain knowledge, which could lead to ill-posed results that are sometimes inconsistent with the essential neurological principles. PURPOSE: Integrating systems biology modeling with machine learning, the study aims to assist clinical AD prognosis by providing a subpopulation classification in accordance with essential biological principles, neurological patterns, and cognitive symptoms. METHODS: We propose a novel pathology steered stratification network (PSSN) that incorporates established domain knowledge in AD pathology through a reaction-diffusion model, where we consider non-linear interactions between major biomarkers and diffusion along the brain structural network. Trained on longitudinal multimodal neuroimaging data, the biological model predicts long-term evolution trajectories that capture individual characteristic progression pattern, filling in the gaps between sparse imaging data available. A deep predictive neural network is then built to exploit spatiotemporal dynamics, link neurological examinations with clinical profiles, and generate subtype assignment probability on an individual basis. We further identify an evolutionary disease graph to quantify subtype transition probabilities through extensive simulations. RESULTS: Our stratification achieves superior performance in both inter-cluster heterogeneity and intra-cluster homogeneity of various clinical scores. Applying our approach to enriched samples of aging populations, we identify six subtypes spanning AD spectrum, where each subtype exhibits a distinctive biomarker pattern that is consistent with its clinical outcome. CONCLUSIONS: The proposed PSSN (i) reduces neuroimage data to low-dimensional feature vectors, (ii) combines AT[N]-Net based on real pathological pathways, (iii) predicts long-term biomarker trajectories, and (iv) stratifies subjects into fine-grained subtypes with distinct neurological underpinnings. PSSN provides insights into pre-symptomatic diagnosis and practical guidance on clinical treatments, which may be further generalized to other neurodegenerative diseases.

Metal-Acid Interface Engineering in Pd-WOx Bifunctional Catalysts for the Hydroalkylation Tandem Reaction of Benzene.

The hydroalkylation tandem reaction of benzene to cyclohexylbenzene (CHB) provides an atom economy route for conversion and utilization of benzene; yet, it presents significant challenges in activity and selectivity control. In this work, we report a metal-support synergistic catalyst prepared via calcination of W-precursor-containing montmorillonite (MMT) followed by Pd loading (denoted as Pd-mWOx/MMT, m = 5, 15, and 25 wt %), which shows excellent catalytic performance for hydroalkylation of benzene. A combination study (X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis, Raman, and density functional theory (DFT) calculations) confirms the formation of interfacial sites Pd-(WOx)-H, whose concentration is dependent on the interaction between Pd and WOx. The optimized catalyst (Pd-15WOx/MMT) exhibits a CHB yield of up to 45.1% under a relatively low hydrogen pressure, which stands at the highest level among state-of-the-art catalysts. Investigations on the structure-property correlation based on in situ FT-IR and control experiments further verify that the Pd-(WOx)-H structure serves as the dual-active site: the interfacial Pd site accelerates benzene hydrogenation to cyclohexene (CHE), while the interfacial Bronsted (B) acid site in Pd-(WOx)-H boosts the alkylation of benzene and CHE to CHB. This study offers a new strategy for the design and preparation of metal-acid bifunctional catalysts, which shows potential application in the hydroalkylation reaction of benzene.

Graph Clustering Analyses of Discontinuous Molecular Dynamics Simulations: Study of Lysozyme Adsorption on a Graphene Surface.

Understanding the interfacial behaviors of biomolecules is crucial to applications in biomaterials and nanoparticle-based biosensing technologies. In this work, we utilized autoencoder-based graph clustering to analyze discontinuous molecular dynamics (DMD) simulations of lysozyme adsorption on a graphene surface. Our high-throughput DMD simulations integrated with a Go̅-like protein-surface interaction model makes it possible to explore protein adsorption at a large temporal scale with sufficient accuracy. The graph autoencoder extracts a low-dimensional feature vector from a contact map. The sequence of the extracted feature vectors is then clustered, and thus the evolution of the protein molecule structure in the absorption process is segmented into stages. Our study demonstrated that the residue-surface hydrophobic interactions and the π-π stacking interactions play key roles in the five-stage adsorption. Upon adsorption, the tertiary structure of lysozyme collapsed, and the secondary structure was also affected. The folding stages obtained by autoencoder-based graph clustering were consistent with detailed analyses of the protein structure. The combination of machine learning analysis and efficient DMD simulations developed in this work could be an important tool to study biomolecules' interfacial behaviors.

Metal-Acid Bifunctional Catalysts toward Tandem Reaction: One-Step Hydroalkylation of Benzene to Cyclohexylbenzene.

The one-step hydroalkylation of benzene to cyclohexylbenzene (CHB) is a technically challenging and economically interesting reaction with great industrial importance, where bifunctional catalysts play a crucial role in such a tandem reaction. In this work, we report H3PW12O40 (HPW) modified Ni nanoparticles (NPs) supported on mixed metal oxides (Ni/MMOs), which are featured by HPW species localized on the surface of Ni NPs (denoted as HPW-Ni/MMOs). The optimal catalyst (0.3HPW-Ni/MMOs) exhibits a satisfactory catalytic performance toward benzene hydroalkylation to CHB with a CHB yield of up to 41.2%, which is the highest standard among previously reported catalysts to date. A combination investigation based on HR-TEM, XPS, XANES, and in situ FT-IR verified the electron transfer from the W atom to the adjacent Ni atom, which facilitated the formation and desorption of cyclohexene (CHE) from Ni followed by the alkylation reaction of benzene and CHE at the interfacial Brønsted (B) acid sites of HPW, accounting for the significantly enhanced catalytic behavior. It is proposed that the HPW-Ni interface structure in xHPW-Ni/MMOs samples provides unique adsorption sites for benzene and CHE with a moderate adsorption strength, which serve as the intrinsic active center for this reaction: the Ni site promotes the hydrogenation of benzene to CHE, while the B acid site in HPW facilitates the alkylation of CHE and benzene to produce CHB. This work provides a fundamental understanding of the metal-acid synergistic catalysis toward the hydroalkylation reaction, which can be extended to the design and preparation of high-performance catalysts used in tandem reactions.

Flexible Hydrophobic CFP@PDA@AuNPs Stripes for Highly Sensitive SERS Detection of Methylene Blue Residue.

Considering the inherent hydrophilic and porous nature of paper, the rapid absorption and diffusion of aqueous analyte solutions on paper-based SERS substrates may severely affect the Raman detection sensitivity and accuracy in the detection of target molecules. In this work, a series of hydrophobic CFP@PDA@AuNPs stripes were obtained through in situ synthesizing of gold nanoparticles (AuNPs) on a polydopamine (PDA)-decorated cellulose filter paper (CFP) and functionalized with perfluorodecanethiol (PFDT). When the SERS performance of the substrates was examined using 4-ATP, the hydrophobic CFP@PDA@AuNPs substrate showed superior sensitivity, reproducibility and stability due to the hydrophobic enrichment effect, with the detection limit decreasing to 10-9 M and the enhancement factor as high as 2.55 × 107. More importantly, it was feasible to apply the hydrophobic paper substrate as an excellent SERS sensor to detect methylene blue (MB) residues in lake water in a highly sensitive manner. The lowest detectable limit of MB was 100 nM, and it showed a low relatively standard deviation (RSD) value of 5.28%. Hydrophobic CFP@PDA@AuNPs stripes may serve as excellent sensors for target molecule detection and have tremendous potential in food security, and environmental and chemical detection.

Enriched-Bromine Surface State for Stable Sky-Blue Spectrum Perovskite QLEDs With an EQE of 14.6.

Halogen vacancies are of great concern in blue-emitting perovskite quantum-dot light-emitting diodes because they affect their efficiency and spectral shift. Here, an enriched-bromine surface state is realized using a facile strategy that employs a PbBr2 stock solution for anion exchange based on Cd-doped perovskite quantum dots. It is found that the doped Cd ions are expected to reduce the formation energy of halogen vacancies filled by the external bromine ions, and the excess free bromine ions in solution are enriched in the surface by anchoring with halogen vacancies as sites, accompanied with the shedding of surface long-chain ligands during the anion exchange process, resulting in a Br-rich and "neat" surface. Moreover, the surface state exhibits good passivation of the surface defects of the controlled perovskite QDs and simultaneously increases the exciton binding energy, leading to excellent optical properties and stability. Finally, the sky-blue emitting perovskite quantum-dot light-emitting diodes (QLEDs) (490 nm) are conducted with a record external quantum efficiency of 14.6% and current efficiency of 19.9 cd A-1 . Meanwhile, the electroluminescence spectra exhibit great stability with negligible shifts under a constant operating voltage from 3 to 7 V. This strategy paves the way for improving the efficiency and stability of perovskite QLEDs.

A sliver deposition signal-enhanced optical biomolecular detection device based on reduced graphene oxide.

The development of high-sensitive biomolecular detection system is of great significance for diseases early diagnosis. The novel optical sensor based on the polarization-sensitive absorption of graphene has a great potential in biological detection. However, the detection sensitivity of the device can hardly meet the needs of clinical analysis currently. This study applies sliver deposition signal amplification to the optical biomolecular detection device based on reduced graphene oxide for the sensitive immunoassay. In redox cycling enzymatic silver deposition reaction, the more alkaline phosphatase label bound on chip surface will cause a faster silver deposition rate. The specific antibody detection confirms that the sliver deposition can enhance the detection signal significantly. In cardiac biomarker Creatine Kinase-MB measurement, the minimum detection concentration is 0.1 ng/mL. To be more important, within the range from detection limit to 10 ng/mL, the signal intensity is highly correlated with target protein concentration, so the biomolecular detection device can meet clinical assay requirements. The signal-enhanced optical biomolecular detection device based on reduced graphene oxide shows excellent sensitivity and selectivity, and provides a new strategy for biomolecules detection, which can be applied in diseases accurate prediction and diagnosis.

Highly crystallized glass-ceramics from high content gold tailings via a one-step direct cooling method.

Highly crystalline glass-ceramics were successfully manufactured via a one-step direct cooling method using Shuangqishan (Fujian, China) gold tailings as raw materials. A series of glass-ceramics were prepared by controlling the gold tailings addition and post-treatment. X-ray diffraction results show that the crystalline phase of glass-ceramics samples with high tailing addition content (65-80 wt%) is akermanite phase (Ca2MgSi2O7). By contrast, the main phase of 60 wt% and 55 wt% tailings addition samples is diopside (CaMgSi2O6) crystalline phase. In addition, although glass-ceramics have typical fracture characteristics of brittle materials, the crack propagation in the fracture process is disturbed by grains, resulting in the deviation of the fracture path in terms of macroscopic and microcosmic observation. Based on the investigation of samples with different tailings additions, glass-ceramics with 60 wt% tailings contents show excellent mechanical properties with a density of 2.89 g cm-3, a Vickers hardness value of 8.17 GPa, and a flexural strength of 116 MPa after 950 °C heat treatment. This study further confirms the possibility of using Shuangqi Mountain gold tailings as the raw materials for highly crystalline glass-ceramics, which shows great potential for application in mass production.

Tuning the Thermal Transport of Hexagonal Boron Nitride/Reduced Graphene Oxide Heterostructures.

Tuning the thermal properties of materials is considered to be of crucial significance for improving the performance of electronic devices. Along these lines, the development of van der Waals (vdW) heterostructures becomes an effective solution to affect the thermal transport mechanisms. However, vdW interactions usually block phonon transport, which leads to a reduction in thermal conductivity. In this work, we experimentally demonstrate a large enhancement in the thermal conductivity of a vdW heterostructure composed of few-layer hexagonal boron nitride (h-BN) and reduced graphene oxide (RGO). By controlling the reduction temperature of RGO and changing the thickness of h-BN, the thermal conductivity of the RGO is increased by nearly 18 times, namely, from 91 to 1685 W m-1 K-1. Photothermal scanning imaging is used to reveal the changes in the heat transfer and temperature distribution of the h-BN/RGO heterostructure. Both photothermal scanning and Raman spectroscopy experiments show that the vdW interaction between h-BN and RGO can greatly increase the thermal conductivity of RGO, which is in contrast to the conventional understanding that vdW interaction reduces thermal conductivity. Our work paves the way for the manipulation of the thermal conductivity of two-dimensional (2D) heterostructures, which could be of great significance for future nanoelectronic circuits.

Photothermal-Transport Imaging and Thermal Management of 2D Materials.

Thermal management plays an important role in miniaturized and integrated nanoelectronic devices, where finding ways to enable efficient heat-dissipation can be critical. 2D materials, especially graphene and hexagonal boron nitride (h-BN), are generally regarded as ideal materials for thermal management due to their high inherent thermal conductivity. In this paper, a new method is reported, which can be used to characterize thermal transport in 2D materials. The separation of pumping from detection can obtain the temperature at different distances from the heat source, which makes it possible to study the heat distribution of 2D materials. Using this method, the thermal conductivity of graphene and molybdenum disulfide is measured, and the thermal diffusion for different shapes of graphene is explored. It is found that thermal transport in graphene changes when the surrounding environment changes. In addition, thermal transport is restricted at the boundary. These processes are accurately simulated using the finite element method, and the simulated results agree well with the experiment. Furthermore, by depositing a layer of h-BN on graphene, the heat-dissipation characteristics of graphene become tunable. This study introduces and describes a new method to investigate and optimize thermal management in 2D materials.

MoOx-Decorated Co-Based Catalysts toward the Hydrodeoxygenation Reaction of Biomass-Derived Platform Molecules.

Catalytic conversion of a biomass derivative (levulinic acid, LA) to a high value-added product (γ-valerolactone, GVL) has attracted much attention, in which the control of catalytic selectivity plays an important role. Herein, a stepwise method was developed to prepare Co-MoOx catalysts via topological transformation (calcination reduction) from layered double hydroxide (Mo/CoAl-LDH) precursors. X-ray diffraction, high-resolution transmission electron microscopy, and hydrogen temperature-programmed reduction demonstrate the formation of MoOx-decorated Co structures of Co-MoOx samples. Remarkably, the sample that is reduced at 500 °C is featured with the most abundant interfacial Coδ+ (denoted as Co-MoOx-500), which exhibits an excellent catalytic performance toward the hydrodeoxygenation (HDO) reaction of several biomass-derived platform molecules (furfural, FAL; succinic acid, SA; 5-hydroxymethyl-furfural, HMF; and levulinic acid, LA). Especially, this optimal catalyst displays a high yield (99%) toward the HDO reaction of LA to GVL, which stands at the highest level among non-noble metal catalysts. The combination of in situ FT-IR characterization and theoretical calculation further confirms that interfacial Coδ+ sites in Co-MoOx-500 act as adsorption active sites for the polarization of a C═O bond in an LA molecule, which simultaneously promotes C═O hydrogenation and C-O cleavage. Moreover, the MoOx overlayer suppresses the formation of byproducts by covering the Co0 sites. This work offers a cost-effective and efficient catalyst, which can be potentially applied in catalytic conversion of biomass-derived platform molecules.

Dimensional Gradient Structure of CoSe2@CNTs-MXene Anode Assisted by Ether for High-Capacity, Stable Sodium Storage.

Recently, abundant resources, low-cost sodium-ion batteries are deemed to the new-generation battery in the field of large-scale energy storage. Nevertheless, poor active reaction dynamics, dissolution of intermediates and electrolyte matching problems are significant challenges that need to be solved. Herein, dimensional gradient structure of sheet-tube-dots is constructed with CoSe2@CNTs-MXene. Gradient structure is conducive to fast migration of electrons and ions with the association of ether electrolyte. For half-cell, CoSe2@CNTs-MXene exhibits high initial coulomb efficiency (81.7%) and excellent cycling performance (400 mAh g-1 cycling for 200 times in 2 A g-1). Phase transformation pathway from crystalline CoSe2-Na2Se with Co and then amorphous CoSe2 in the discharge/charge process is also explored by in situ X-ray diffraction. Density functional theory study discloses the CoSe2@CNTs-MXene in ether electrolyte system which contributes to stable sodium storage performance owing to the strong adsorption force from hierarchical structure and weak interaction between electrolyte and electrode interface. For full cell, CoSe2@CNTs-MXene//Na3V2 (PO4)3/C full battery can also afford a competitively reversible capacity of 280 mAh g-1 over 50 cycles. Concisely, profiting from dimensional gradient structure and matched electrolyte of CoSe2@CNTs-MXene hold great application potential for stable sodium storage.

Interface Engineering of a Sandwich Flexible Electrode PAn@CoHCF Rooted in Carbon Cloth for Enhanced Sodium-Ion Storage.

With the growth of demand for flexible devices, the development of flexible electrodes used in energy storage devices has attracted much attention of researchers. In this work, a thin flexible cathode of Prussian blue analogue@polyaniline rooted in carbon cloth has been fabricated. The Prussian blue analogue (PBA) is an electrochemically active material grafted on flexible carbon cloth substrates, which had been precoated with polyaniline. Polyaniline as an intermediate layer can not only improve the overall electronic conductivity of the electrode but also enhance the adhesion and load of the PBAs. The electrochemical properties of the flexible cathode with a "sandwich" structure were determined in half-cells, with a superior capacity of 151 mA h·g-1 and a striking cyclability with 96% capacity retention over 100 cycles at 100 mA h·g-1. This work proposes a novel perspective for the structural construction and material synthesis of flexible positive electrodes and gives new options for the practical application of flexible batteries.

Suppressing ion migration of CsPbBrxI3-xnanocrystals by Nickel doping and the application in high-efficiency WLEDs.

All inorganic perovskite nanocrystals CsPbX3(X = Cl, Br, I) are the great potential candidates for the application of high-performance light emitting diodes (LED) due to their high Photoluminescence Quantum Yield (PLQY), high defect tolerance, narrow full-width half-maximum and tunable wavelength of 410-700 nm. However, the application of red-emitting (630-650 nm) CsPbBrxI3-xnanocrystals are perplexed by phase segregation due to the composition of mixed halides and the difference in halide ion mobility. Herein, we provide an effective strategy to suppressing the migration of Br/I ions through Ni2+doping via a facile Hot-Injection method and the PLQY was improved as well. DFT calculations show that the introduction of Ni2+causes a slight contraction of the host crystal structure, which improves the bond energy between Pb and halides and reduces the level of surface defects. Therefore, the phase stability is improved by Ni2+doping because the phase segregation caused by ion migration in the mixed phase is effectively inhibited. Meanwhile, the non-radiative recombination in the exciton transition process is reduced and the PLQY is improved. What's more, benefiting from the suppressed ion migration and enhanced PLQY, we combine the Ni2+-doped CsPbBrxI3-xnanocrystals with different Br/I ratios and YAG: Ce3+phosphors as color conversion layers to fabricate high efficiency WLED. When the ratio of Br/I is 9:11, WLED has a color coordinate of (0.3621, 0.3458), the color temperature of 4336 K and presents a high luminous efficiency of 113.20 lm W-1, color rendering index of 94.9 under the driving current of 20 mA and exhibits excellent stability, which shows great potential in the application of LED.

A Ni-doping-induced phase transition and electron evolution in cobalt hexacyanoferrate as a stable cathode for sodium-ion batteries.

Prussian blue analogues are potential competitive energy storage materials due to their diverse metal combinations and wide three-dimensional ion channels. Here, we prepared a new highly crystalline monoclinic nickel-doped cobalt hexacyanoferrate via a feasible and simple one-step co-precipitation method. In the process of sodium-ion de-intercalation, three stable charge and discharge platforms, which are consistent with the cyclic voltammetry performance, are seen for the first time, showing the function of nickel ions in Prussian blue. Furthermore, the charge transfer and structural evolution caused by the transmission of sodium ions were well revealed via ex situ XRD, ex situ XPS, and in situ EIS studies. Simulation calculations are performed relating to the energy band structure and the highest-occupied bonding orbitals of the system in different charge states, revealing the charge and discharge mechanism of the nickel-doped material and the reason for the emergence of the new platform at low voltages. In addition, NaNi0.17Co0.83Fe(CN)6 also delivers a striking capacity of 146 mA h g-1 and superior cyclability, with 93% capacity retention over 100 cycles; it can be considered as a promising alternative cathode material for use in sodium-ion batteries.

Highly efficient and blue-emitting CsPbBr3 quantum dots synthesized by two-step supersaturated recrystallization.

Highly efficient and blue-emitting CsPbBr3 quantum dots were successfully synthesized by two-step supersaturated recrystallization under ambient condition. This method could control the particle size within 2.8 nm, thus resulting in strong quantum confinement effect of the products. The as-synthesized CsPbBr3 quantum dots presented outstanding optical properties with highest photo-luminescence quantum yield of 87.20% and longest PL lifetime of 12.24 ns. The blue light-emitting diode made from the CsPbBr3 quantum dots exhibited a CIE coordinate (0.14, 0.10), in good agreement with the standard blue CIE coordinate (0.14, 0.08) of National Television System Committee (NTSC).

Synthesis of Eco-Friendly High PL Lifespan Manganese-Doped CuInZnS/ZnS QDs for White LED Applications.

Environmentally friendly and long PL lifespan Mn-doped CuInZnS (Mn:CIZS) and CuInZnS/ZnS (Mn:CIZS/ZnS) QDs, with respective red and yellow emissions, were synthesized using nontoxic precursors via a facile dual-step process based on the one-pot method. The resulting Mn:CIZS and Mn:CIZS/ZnS QDs exhibited confirmed strong red and yellow photoluminescence emissions at approximately 654 nm and 580 nm, respectively. The measured PL decay lifespan for the Mn: CIZS QDs is 2.52 µs due to well-organized surface passivation through the ZnS shell; the average PL lifespan for the Mn:CIZS/ZnS QDs is extended to 6.28 µs. Moreover, the WLEDs were composed of the Mn:CIZS/ZnS QDs. The resulting WLEDs offered admirable optical attributes, such as an excellent Ra of 89, a low Tc of 5075 K and radiant white light emanation at 60 mA functional current. Therefore, the outputs highlight the Mn:CIZS/ZnS QDs as hopeful cadmium-free resources for the interest of optoelectronics exploration.

Carbon electrode engineering for high efficiency all-inorganic perovskite solar cells.

Carbon-based inorganic perovskite solar cells (PSCs) have demonstrated an excellent performance in the field of photovoltaics owing to their simple fabrication techniques, low-cost and superior stability. Despite the lower efficiency of devices with a carbon electrode compared with the conventional structure, the potential applications in large scale have attracted increasing attention. Herein, we employ a mixed carbon electrode inorganic PSC by incorporating one-dimensional structure carbon nanotubes (CNTs) and two-dimensional Ti3C2-MXene nanosheets into a commercial carbon paste. This mixed carbon electrode, which is different from the pure carbon electrode in showing a point-to-point contact, provides a network structure and multi-dimensional charge transfer path, which effectively increases the conductivity of the carbon electrode and carriers transport. A respectable power conversion efficiency of 7.09% is obtained through carbon/CNT/MXene mixed electrode in CsPbBr3-based solar cells.