Publications by authors named "Gary J Cheng"

Surface nanoengineering can significantly improve the mechanical properties and performance of metals, such as strength, hardness, fatigue, wear resistance, . In this work, we tailored the surface microstructure of GCr15 bearing steel within a thickness of approximately 800 μm using room temperature ultrasonic shot peening (USP) technology. Microstructure characterization studies reveal the formation of gradient nanosized spheroidal carbides and lath-shaped nano-martensite in the GCr15 bearing steel during the USP process.

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Water polluted by toxic chemicals due to waste from chemical/pharmaceuticals and harmful microbes such as E. Coli bacteria causes several fatal diseases; and therefore, water filtration is crucial for accessing clean and safe water necessary for good health. Conventional water filtration technologies include activated carbon filters, reverse osmosis, and ultrafiltration.

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Nanosecond pulsed laser irradiation is employed for synthesis of highly active and stable Pt-based electrocatalysts by anchoring Pt nanoclusters on porous sulfur-doped carbon supports (L-Pt/SC). Strong metal-support interaction (SMSI) between Pt and S induces a local charge rearrangement and modulates the electronic structure of Pt surroundings, thus boosting the reaction kinetics and enhancing stability in long-term hydrogen evolution reaction (HER). The L-Pt/SC catalyst exhibits high activity toward HER, with an overpotential of 23 mV at current densities reaching 10 mA cm and a Tafel slope of 24 mV dec.

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Nanoscale three-dimensional (3D) printing of metals and alloys has faced challenges in speed, miniaturization and deficiency in material properties. Traditional nanomanufacturing relies on lithographic methods with material constraints, limited resolution and slow layer-by-layer processing. This work introduces polymer-free techniques using two-photon decomposition and optical force trapping for free-space direct 3D printing of metals, metal oxides and multimetallic alloys with resolutions beyond optical limits.

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Pulsed laser micropropulsion (PLMP) offers a promising avenue for miniature space craft, yet conventional propellants face challenges in balancing efficiency and stability. An optical-propulsion metastructure strategy using metal-organic frameworks (MOFs) is presented to generate graphene-metal metastructures (GMM), specifically GMM-(HKUST-1), which significantly enhances PLMP performance. This novel approach leverages the unique interaction between pulsed lasers and the precisely engineered GMMs-comprising optimized metal nanoparticle size, graphene layers, and inter-particle gaps-to boost both propulsion efficiency and stability.

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Herein, an in situ "synchro-subtractive-additive" technique of femtosecond laser single-cell surgery (FLSS) is presented to address the inadequacies of existing surgical methods for single-cell manipulation. This process is enabled by synchronized nanoscale three-dimensional (3D) subtractive and additive manufacturing with ultrahigh precision on various parts of the cells, in that the precise removal and modification of a single-cell structure are realized by nonthermal ablation, with synchronously ultrafast solidification of the specially designed hydrogel by two photopolymerizations. FLSS is a minimally invasive technique with a post-operative survival rate of 70% and stable proliferation.

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Femtosecond laser-based technique called two-photon polymerization (TPP) has emerged as a powerful tool for nanofabrication and integrating nanomaterials. However, challenges persist in existing three-dimensional (3D) nanoprinting methods, such as slow layer-by-layer printing and limited material options due to laser-matter interactions. Here, we present an approach to 3D nanoprinting called free-space nanopainting, using an optical force brush (OFB).

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Conventional propellant materials, such as polymers and single metal elements, have long been investigated for their potential in pulsed laser micropropulsion (LMP) technology. However, achieving superior LMP efficiency through physical mixing of these materials remains a significant challenge. This study presents a paradigm shift by introducing porous crystalline polymers, known as metal-organic frameworks (MOFs), as novel propellants in pulsed LMP.

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Due to the advantages of high porosity, excellent conductivity, and tunable morphology, carbonized metal-organic framework (C-MOF) is expected to become an ideal material for constructing high-performance flexible pressure sensor. Herein, to achieving the suitable morphology of C-MOF for piezoresistive sensors, a rapid thermal process (RTP) was used for carbonization of NiCo-MOF, and the petal-shaped NiCo alloy nanoparticles/nanoporous carbon composites (NiCo-NPCs) were obtained. Compared with NiCo-NPCs carbonized by common thermal process (CTP), NiCo-NPCs carbonized by RTP exhibit a modified morphology with smaller particle size and larger most frequent pore diameter.

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The orientation of crystals on the substrate and the presence of defects are critical factors in electro-optic performance. However, technical approaches to guide the orientational crystallization of electro-optical thin films remain challenging. Here, a novel physical method called magnetic-field-assisted pulse laser annealing (MAPLA) for controlling the orientation of perovskite crystals on substrates is reported.

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The exchange bias (EB) effect plays an undisputed role in the development of highly sensitive, robust, and high-density spintronic devices in magnetic data storage. However, the weak EB field, low blocking temperature, as well as the lack of modulation methods, seriously limit the application of EB in van der Waals (vdW) spintronic devices. Here, we utilized pressure engineering to tune the vdW spacing of the two-dimensional (2D) FePSe/FeGeTe heterostructures.

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Substrate-supported catalysts with atomically dispersed metal centers are promising for driving the carbon dioxide reduction reaction (CORR) to produce value-added chemicals; however, regulating the size of exposed catalysts and optimizing their coordination chemistry remain challenging. In this study, we have devised a simple and versatile high-energy pulsed laser method for the enrichment of a Bi "single atom" (SA) with a controlled first coordination sphere on a time scale of nanoseconds. We identify the mechanistic bifurcation routes over a Bi SA that selectively produce either formate or syngas when bound to C or N atoms, respectively.

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Wearable sweat sensors have been developed rapidly in recent years due to the great potential in health monitoring. Developing a convenient manufacturing process and a novel structure to realize timeliness and continuous monitoring of sweat is crucial for the practical application of sweat sensors. Herein, inspired by the striped grooves and granular structures of bamboo leaves, we realized an epidermal patch with biomimetic multilevel structural microfluidic channels for timeliness monitoring of sweat via 3D printing and femtosecond laser processing.

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Optical antireflection surfaces equipped with subwavelength nanocone arrays are commonly used to reach broadband supertransmissivity but are limited by the lack of wear resistance. We design and manufacture a structured surface with robust antireflection structures (R-ARS) composed of substrate-engraved nanocone arrays with micro-grid-shaped walls as protective armor. An ultrafast laser beam is used to selectively ablate and dope the metal from the deposited film into the subsurface of optical substrates to strengthen self-assembled nanoparticles formed during plasma etching as masks for nanocones.

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Copper (Cu) removal efficiency is a key parameter in the processing of Cu-based electronic devices. Herein, a nitrogen plasma-assisted picosecond (ps) laser process for Cu removal is presented. Based on the cleaning and activation effect of nitrogen plasma on the surface of Cu film in ps-laser ablation, the removal efficiency can be significantly improved.

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Pivotal to functional van der Waals stacked flexible electronic/excitonic/spintronic/thermoelectric chips is the synergy amongst constituent layers. However; the current techniques viz. sequential chemical vapor deposition, micromechanical/wet-chemical transfer are mostly limited due to diffused interfaces, and metallic remnants/bubbles at the interface.

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The development of endocrine resistance is a common reason for the failure of endocrine therapies in hormone receptor-positive breast cancer. This review provides an overview of the different types of models that have been developed as tools for studying endocrine resistance. models include cell lines that have been rendered endocrine-resistant by treatment; cell lines with resistance mechanisms, including genetic alterations; three-dimensional (3D) spheroid, co-culture, and mammosphere techniques; and patient-derived organoid models.

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Increasing both clean water and green energy demands for survival and development are the grand challenges of our age. Here, we successfully fabricate a novel multifunctional 3D graphene-based catalytic membrane (3D-GCM) with active metal nanoparticles (AMNs) loading for simultaneously obtaining the water purification and clean energy generation, via a "green" one-step laser scribing technology. The as-prepared 3D-GCM shows high porosity and uniform distribution with AMNs, which exhibits high permeated fluxes (over 100 L m h) and versatile super-adsorption capacities for the removal of tricky organic pollutants from wastewater under ultra-low pressure-driving (0.

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Laser is a powerful tool for the synthesis of nanomaterials. The intensive laser pulses delivered to materials within nanoseconds allow the formation of novel structures that are inaccessible for conventional methods. Layered double hydroxide (LDH) nanostructures with high porosity, suitable dopants, and rich defects are desirable for catalysts, however, tremendously difficult in a one-pot synthesis.

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Nanoalloys, especially high-entropy nanoalloys (HENAs) that contain equal stoichiometric metallic elements in each nanoparticle, are widely used in vast applications. Currently, the synthesis of HENAs is challenged by slow reaction kinetics that leads to phase segregation, sophisticated pretreatment of precursors, and inert conditions that preclude scalable fabrication of HENAs. Here, we report direct conversion of metal salts to ultrafine HENAs on carbonaceous support by nanosecond pulsed laser under atmospheric conditions.

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The reduction of CO to useful chemicals by solar irradiation has been of great interest in recent years to tackle the greenhouse effect. Compared with inorganic metal oxide particles, carbonaceous materials, such as graphene, are excellent in light absorption; however, they lack in activity and selectivity because of the challenge to manipulate the band gap and optimize the electron-hole separation, which drives the photoreduction process. In this work, inspired by the delicate natural plant leaf structure, we fabricated orderly stacked graphene nanobubble arrays with nitrogen dopant for the coordination of noble metal atoms to mimic the natural photoreduction process in plant leaves.

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Metal-organic framework (MOF) crystals are useful in a vast area of applications because of their unique chemical and physical properties. Manufacturing of an integrated MOF membrane with 3D nanoarchitectures on the surface is especially important for their applications. However, as MOF crystals usually exist as powdery crystals, fabrication of their large area, monolithic, and high-resolution patterns is challenging.

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Structural mechanical metamaterials, with their mass-efficient architectures and unprecedented mechanical properties, are in critical demand for high-performance applications. However, finding the optimal 3D geometries towards a particular property, such as reaching the stiffness upper bound, usually demands high volume of calculations or numerical optimizations. Here we generate structured mechanical metamaterials by imitating the natural occupation of periodic volume by inflated soap films.

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The development of novel materials has challenges besides their synthesis. Materials such as novel MXenes are difficult to probe experimentally due to their reduced size and low stability under ambient conditions. Quantum mechanics and molecular dynamics simulations have been valuable options for material properties determination.

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Spatial manipulation of nanoparticles (NPs) in a controlled manner is critical for the fabrication of 3D hybrid materials with unique functions. However, traditional fabrication methods such as electron-beam lithography and stereolithography are usually costly and time-consuming, precluding their production on a large scale. Herein, for the first time the ultrafast laser direct writing is combined with external magnetic field (MF) to massively produce graphene-coated ultrafine cobalt nanoparticles supported on 3D porous carbon using metal-organic framework crystals as precursors (5 × 5 cm with 10 s).

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