High-performance violet phosphorus photodetectors with van der Waals-assisted contacts

Black phosphorus(BP) as a narrow-bandgap two-dimensional semiconductor material has been extensively studied. And the allotrope violet phosphorus(VP) exhibits wide bandgap properties extending the application in the visible light band. However,due to the Schottky barrier of metal/semiconductor contacts(M/S), further device application of VP is limited. Here, VP-based photodetectors with van der Waals-assisted contact were demonstrated, achieving quasi-Ohmic M/S contacts. The output characteristi...     

Investigating TEP as a greener alternative to NMP in Ni-rich cathode fabrication

In the past decade,the surging demand for portable electronics,electric vehicles,and stationary energy storage grids has triggered a noticeable rise in the production of Li-ion batteries(LIBs).However,this swift rise is now hindered by relying on the use of N-methyl-2-pyrrolidone(NMP),a repro-toxic solvent,in the current cathode processing of LIBs.To overcome this challenge,here we have investigated triethyl phosphate(TEP) as a greener alternative to NMP.The compatibility with polyvinylidene flu...     

Plasma preparation of highly reactive Ag-Cu NPs anchored in N-PC as catalysts for Aluminum-air battery

Efficient, stable and economical catalysts play a crucial role in enhancing the kinetics of slow oxygen reduction reactions(ORR) in Aluminum-air batteries. Among the potential next-generation candidates,Ag catalysts are promising due to their high activity and low cost, but weaker oxygen adsorption has hindered industrialization. To address this bottleneck, Ag-alloying has emerged as a principal strategy. In this work, we successfully prepared Ag-Cu nanoparticles(NPs) with a rich eutectic phase ...     

Methanation of CO/CO2 for power to methane process: Fundamentals,status, and perspectives

Power-to-methane(P2M) processes, by converting electricity from renewable energy to H₂ and then into other high value-added and energy-intense chemicals in the presence of active catalysts, have become an effective solution for energy storage. However, the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation, which requires an excellent heterogeneous catalyst to withstand the harsh conditions. Based on these ...     

Overview of finite elements simulation of temperature profile to estimate properties of materials 3D-printed by laser powder-bed fusion

Laser powder bed fusion(LPBF),like many other additive manufacturing techniques,offers flexibility in design expected to become a disruption to the manufacturing industry.The current cost of LPBF process does not favor a try-anderror way of research,which makes modelling and simulation a field of superior importance in that area of engineering.In this work,various methods used to overcome challenges in modeling at different levels of approximation of LPBF process are reviewed.Recent efforts made towards a reliable and computationally effective model to simulate LPBF process using finite element(FE)codes are presented.A combination of ray-tracing technique,the solution of the radiation transfer equation and absorption measurements has been used to establish an analytical equation,which gives a more accurate approximation of laser energy deposition in powder-substrate configuration.When this new analytical energy deposition model is used in in FE simulation,with other physics carefully set,it enables us to get reliable cooling curves and melt track morphology that agree well with experimental observations.The use of more computationally effective approximation,without explicit topological changes,allows to simulate wider geometries and longer scanning time leading to many applications in real engineering world.Different applications are herein presented including:prediction of printing quality through the simulated overlapping of consecutive melt tracks,simulation of LPBF of a mixture of materials and estimation of martensite inclusion in printed steel.     

Organic Nanocrystals Based on a Solid-emission-tunable AIEgen for Cell Imaging

The development of fluorescent nanocrystals based on organic small molecules is of great importance in bioimaging due to the merits of easy modification,high brightness and excellent photostability,however suffering from the emission-detrimental aggregation-caused quenching(ACQ)effect.Herein,we successfully designed and synthesized an AIE-active di(N,N-dimethylaniline)-dibenzofulvene(named as NFTPE),which exhibits the crystallization-induced emission enhancement(CIEE)effect.Interestingly,two types of yellow-and orange-emissive crystals for NFTPE were obtained,exhibiting aggregation microenvironment-dependent emission tuning in the solid state.Single-crystal analysis and density functional theory(DFT)calculations reveal that different aggregation microenvironments result in the distinct molecular conformation for various emission.Excitingly,the crystallization of NFTPE in an aqueous solution under the assistance of amphiphilic PEG polymer matrices could be monitored in situ by the fluorescence changes,facilitating the preparation of NFTPE nanocrystals(NFTPE-NCs)by adjusting the aggregation microenvironment.The obtained NFTPE-NCs exhibit the superior performance in cell imaging in respect to high brightness,photostability,and biocompatibility,thus demonstrating the potential in bioimaging applications.     

Circumvent PEGylation dilemma by implementing matrix metalloproteinase-responsive chemistry for promoted tumor gene therapy

Surface modification by poly(ethylene glycol) (PEGylation) has been acknowledged as a powerful strategy in minimizing non-specific reactions for biomedical devices. Once applied into manufacture of drug/gene delivery systems, PEGylation has demonstrated to significantly improve their biocompatibility and stealthiness in physiological environment. Nonetheless, reluctant cell membrane affinities thus cellular uptake efficiencies owing to PEGylation brought up further issues that are imperative to be resolved. Pertain to this PEGylation dilemma, we attempted to introduce peptide (GPLGVRG) linkage between block copolymer of PEG-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} PAsp(DET), wherein the cationic PAsp(DET) could self-assemble with pDNA into nanoscaled complex core. Noteworthy was the peptide linkage whose amino acids sequence could be specifically recognized and degraded by matrix metalloproteinases (MMPs) (overexpressed in extracellular milieu of tumors). Therefore, our subsequent studies validated facile detachment of PEGylation from the aforementioned polyplex micelles upon treatment of MMPs, which elicited improved cytomembrane affinities and cellular uptake efficiencies. In addition, promoted escape from endosome entrapment was also confirmed through direct endosome membrane destabilization by PAsp(DET), which was further elucidated to be attributable to dePEGylation as well as elevated charged density of PAsp(DET) in acidic endosomes. These benefits from dePEGylation eventually contributed to promoted gene expression at the affected cells and potent tumor growth suppression based on anti-angiogenic approach. Therefore, our developed strategy has provided a facile approach in overcoming the dilemma of PEGylation, which could be informative in design of drug/gene delivery systems.     

Recent advances on carborane-based ligands in low-valent group 13 and group 14 elements chemistry

Carboranes are a class of polyhedral boron-carbon molecular clusters, they can serve as versatile ligands in stabilizing low-valent main group element compounds, due to their exceptionally thermal and chemical stabilities, easy modifications at the cage carbon vertices, as well as large spherical steric effects. These carborane-based ligands provide interesting opportunities for the synthesis of low-valent main group element compounds with novel structure and reactivity, which indeed enrich the ...     

Synthesis and Characterization of a Novel Podophyllotoxin Derivative Containing a Cyclohexadienone Group

4β-Azido-4-demethyl-4'-O-demethyl-epipodophyllotoxin reacted with phenyliodonium diacetate in MeOH at room temperature to synthesize a novel podophyllotoxin derivative containing a cyclohexadienone group with the original configurations of C2 and C4,which are required for the antitumor activities.The component and structure of the pro-duct were confirmed using elemental analysis,high-resolution mass spectrum,1H and 13C NMR spectra,and infrared spectrum.Furthermore,the fragmentation routes of the product were fully assigned with electron-impact time-of-flight mass spectrometry(EI-TOF MS),which can also be used for the structural elucidation based on the molecular ion at m/z 455(16%)and three novel characteristic fragment ions at m/z 183(37%),425(7%),and 199(5%).The cyclohexadienone product is sensitive to acidic media.When it is treated with a trace of acid,another novel derivative containing an orthoquinone moiety is formed,which links with the metabolism of the cancer inhibitors.     

A gauge theory for two-band model of Chern insulators and induced topological defects

In this paper a gauge theory is proposed for the two-band model of Chern insulators.Based on the so-calle't Hooft monopole model,a U(1)Maxwell electromagnetic sub-field is constructed from an SU(2)gauge field,from which arise two types of topological defects,monopoles and e2 merons.We focus on the topological number in the Hall conductance σ_xy=e²/hC,where C is the Chern number.It is discovered that in the monopole case C is indeterminate,while in the meron case C takes different values,due to a varying on-site energy m.As a typical example,we apply this method to the square lattice and compute the winding numbers(topological charges)of the defects;the C-evaluations we obtain reproduce the results of the usual literature.Furthermore,based on the gauge theory we propose a new model to obtain the high Chern numbers|C|=2,4.