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The stable coexistence of insulating and metallic phases in strained vanadium dioxide (VO2) has garnered significant research interest due to the intriguing phase transition phenomena. However, the temporal behavior of charge carriers in different phases of VO2 remains elusive. Herein, we employ near-field optical nanoscopy to capture nanoscale alternating phase domains in bent VO2 nanobeams. By conducting transient measurements across the different phases, we observed a prolonged carrier recombination lifetime in the metallic phase of VO2, accompanied by an accelerated diffusion process. Our findings reveal nanoscale carrier dynamics in VO2 nanobeams, offering insights that can facilitate further investigations into phase-change materials and their potential applications in sensing and microelectromechanical devices.

Nitrogen-vacancy (NV-) centers in nanodiamonds have emerged as a versatile platform for a wide range of applications, including bioimaging, photonics, and quantum sensing. However, the widespread adoption of nanodiamonds in practical applications has been hindered by the challenges associated with patterning them into high-resolution features with sufficient throughput. In this work, we overcome these limitations by introducing a direct laser-writing bubble printing technique that enables the precise fabrication of two-dimensional nanodiamond patterns. The printed nanodiamonds exhibit a high packing density and strong photoluminescence emission, as well as robust optically detected magnetic resonance (ODMR) signals. We further harness the spatially resolved ODMR of the nanodiamond patterns to demonstrate the mapping of two-dimensional temperature gradients using high frame rate widefield lock-in fluorescence imaging. This capability paves the way for integrating nanodiamond-based quantum sensors into practical devices and systems, opening new possibilities for applications involving high-resolution thermal imaging and biosensing.

Defects in microarchitected materials exhibit a dual nature, capable of both unlocking innovative functionalities and degrading their performance. Specifically, while intentional defects are strategically introduced to customize and enhance mechanical responses, inadvertent defects stemming from manufacturing errors can disrupt the symmetries and intricate interactions within these materials. In this study, we demonstrate a nondestructive optical imaging technique that can precisely locate defects inside microscale metamaterials, as well as provide detailed insights on the specific type of defect.

C-H bond activation enables the facile synthesis of new chemicals. While C-H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C-H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C-C coupling mediated by 2D TMDCs to promote C-H activation. Our results shed light on 2D materials for C-H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials.

We present a novel method for fabricating highly customizable three-dimensional structures hosting quantum sensors based on nitrogen vacancy (NV) centers using two-photon polymerization. This approach overcomes challenges associated with structuring traditional single-crystal quantum sensing platforms and enables the creation of complex, fully three-dimensional, sensor assemblies with submicroscale resolutions (down to 400 nm) and large fields of view (>1 mm). By embedding NV center-containing nanoparticles in exemplary structures, we demonstrate high sensitivity optical sensing of temperature and magnetic fields at the microscale. Our work showcases the potential for integrating quantum sensors with advanced manufacturing techniques, facilitating the incorporation of sensors into existing microfluidic and electronic platforms, and opening new avenues for widespread utilization of quantum sensors in various applications.

Ionic liquids (ILs) are seen as a more sustainable alternative to volatile organic solvents that are accelerating innovations in many industries such as energy storage, separations, and bioprocessing. The ability to effectively deconstruct lignocellulosic biomass is a significant hurdle in the biorefining/bioprocessing industry and presents limitations towards the commercial production of bioproducts (such as biofuels, biomaterials, etc.). Certain ILs have been shown to promote effective lignin removal, cellulose recovery, and sugar yields from various biomass feedstocks such as corn stover, wheat straw, sugarcane bagasse, sorghum, switchgrass, miscanthus, poplar, pine, eucalyptus, and certain mixtures of municipal solid waste. However, these improvements are often counteracted by the limited biocompatibility of ILs, which results in an IL-induced reduction in enzyme activity and stability—an important downstream step in the conversion of biomass to biofuels/bioproducts. As a result, significant efforts have been made to discover and engineer compatible enzyme-IL systems and to improve our understanding on the effect that these ILs have on these systems. This review seeks to examine the impact of ionic liquids on enzymes involved in lignocellulosic biomass deconstruction, with a specific focus on their relevance in the context of pretreatment. Beyond presenting an overview of the ionic liquid pretreatment landscape, we outline the main factors that influence enzyme activity and stability in the presence of ILs This data is consolidated and analyzed to apply this body of knowledge towards new innovations that could lead to improvements in the processing of biomass to biofuels and bioproducts.

Using a new Bayesian Optimization algorithm to guide the design of mechanical metamaterials, we design nonhomogeneous 3D structures possessing the Cauchy symmetry, which dictates the relationship between continuum and atomic deformations. Recent efforts to merge optimization techniques with the design of mechanical metamaterials has resulted in a concentrated effort to tailor their elastic and post elastic properties. Even though these properties of either individual unit cells or homogenized continua can be simulated using multi-physics solvers and well established optimization schemes, they are often computationally expensive and require many design iterations, rendering the validation stage a significant obstacle in the design of new metamaterial designs. This study aims to provide a framework on how to utilize miniscule computational cost to control the elastic properties of metamaterials such that specific symmetries can be accomplished. Using the Cauchy symmetry as a design objective, we engineer structures through the strategic arrangement of 5 different unit cells in a 5×5×5 cubic symmetric microlattice structure. This lattice design, despite constituting a design space with 510 3D lattice configurations, can converge to an effective solution in only 69 function calls as a result of the efficiency of the new Bayesian optimization scheme. To validate the mechanical behavior of the design, the lattice structures were fabricated using multiphoton lithography and mechanically tested, revealing a close correlation between experiments and simulated results in the elastic regime. Ultimately, a similar methodology can be utilized to design metamaterials with other material properties, aspiring to control properties at different length scales, an endeavor that requires inordinate computation cost.

The low mass density and high mechanical strength of graphene make it an attractive candidate for suspended-membrane energy transducers. Typically, the membrane size dictates the operational frequency and bandwidth. However, in many cases it would be desirable to both lower the resonance frequency and increase the bandwidth, while maintaining overall membrane size. We employ focused ion beam milling or laser ablation to create kirigami-like modification of suspended pure-graphene membranes ranging in size from microns to millimeters. Kirigami engineering successfully reduces the resonant frequency, increases the displacement amplitude, and broadens the effective bandwidth of the transducer. Our results present a promising route to miniaturized wide-band energy transducers with enhanced operational parameter range and efficiency.

Transition metal dichalcogenides (TMDCs) have shown exceptional optoelectronic properties that can potentially substitute conventional silicon-based devices and be utilized in sensors and energy devices. To exploit their wide array of potential applications, it is necessary to develop methods capable of on demand, location selective, and tunable formation of structures of arbitrary shape. Here, we demonstrated high-speed direct writing of MoSe2 by laser-induced selenization process in vacuum or ambient environment. Laser irradiation on predeposited Se/Mo multilayer promptly forms polycrystalline MoSe2 in a site-selective manner without use of photomask and toxic gas. In situ reflectance measurement and temperature simulation identified distinct characteristic processing stages, revealing that the time required for synthesizing â20 nm-thick MoSe2 polycrystal film is of the order of 10-3s, which is significantly faster than the conventional selenization process using furnace annealing. We believe that the laser synthesis of MoSe2 demonstrated in this study is of general applicability and therefore offers a simple and straightforward route for obtaining arbitrary patterns in TMDCs.

Motivation: The need to diversify their economies is an enduring challenge for fossil fuel‐dependent countries, one which will become ever more important as the world seeks to decarbonize. But the conditions under which major oil‐producing countries (petrostates) seek to diversify their exports—and those under which their attempts succeed—are poorly understood. Purpose: This article tests competing explanations for the successes and failures of petrostates' export diversification. Methods and approach: We employ a comparative case study approach using qualitative evidence from two comparatively successful diversification cases—Egypt and Malaysia—and one less successful case—Kazakhstan—selected using a Theil index of export concentration. Findings: The evidence indicates that Egypt and Malaysia's more successful outcomes stemmed more from necessity and policy design than from differences in domestic institutions and interests. All three countries were motivated to diversify by price volatility and declining revenues at various points from the 1980s to the 2000s and beyond, but reserve depletion was a greater threat in Egypt and Malaysia. As such, they adopted a more balanced approached to diversification, one that combined liberalization with state intervention. Policy implications: These cases suggest that petrostates may be willing and able to diversify as the global shift toward renewables raises the prospect of unburnable oil reserves. Petrostates can diversify efficiently by using a basket of policies that includes a mix of economic liberalization and government intervention to create investment and incentives in non‐oil tradeable sectors and nurture infant industries. Opposition to reforms in petrostates can be addressed by selectively compensating vested interests. [ABSTRACT FROM AUTHOR]

Atomically thin two-dimensional (2D) materials exhibit extraordinary optical, electrical, and mechanical properties. Many functional nanostructures and devices of exceptional performance based on 2D materials have been demonstrated. However, the processing of 2D materials remains challenging due to inadequacies that are mainly driven by high fabrication cost, complex steps, and inefficient impurity control. On the other hand, laser-aided processing techniques offer versatility, nanoscale precision, and high throughput. Numerous efforts have showcased the implementation of laser processing and functionalization of 2D materials to control their physical properties and optimize device functionality. In this Perspective, we summarize research progress on laser-enabled thinning, patterning, doping, and functionalization of 2D materials. Continuing advances in optical processing techniques are anticipated to further accelerate the deployment of 2D materials and devices in many fields, including photonics, optoelectronics, and sensor applications. [ABSTRACT FROM AUTHOR]