Ultrafast Method Research Articles

The influence of SC-CO2 on the shales’ fracture behavior described by using ultra-fast time resolution method and the damage fracture constitutive model: A case study of the Cretaceous Qingshankou formation in Gulong Depression, Songliao Basin, NE China

Supercritical CO2 (SC-CO2), as an innovative non-aqueous fracturing fluid, has gained extensive application in arid regions. However, its influence on the fracture propagation behavior of shale in very short timescales remains poorly understood. Therefore, a series of three-point bending tests were conducted on shale samples with 0°-90° bedding inclinations. To describe the influence of water-heat-SC-CO2 treatment, a damage fracture constitutive model based on a normal distribution was developed. The theoretical fitting curves of this constitutive model agree well with the experimental results. The whole crack propagation processes were captured using the ultra-fast time resolution method, achieving a time resolution of fast to 15 ps. Identical three-point bending tests were repeated after subjecting the shale samples to water-heat-SC-CO2 treatment for 48 h. The experimental results reveal that after the water-heat-SC-CO2 treatment, there were significant changes in the key mechanical parameters of shale samples. Moreover, the influence of water-heat-SC-CO2 was observed to increase progressively with the bedding inclinations. And by combining the image captured by the ultra-fast time resolution method with this constitutive model, the fracture behavior change of the shale sample after water-heat-SC-CO2 treatment predominantly is affected by the weak planes of shale, with negligible influence on the matrix.

Programmable and rapid fabrication of complex-shape ceramics

Shaping of ceramics is crucial. Current techniques cannot easily and rapidly shape ceramics without weakening their properties, especially for piezoceramics. We present an ultrafast ceramic shaping method that leverages thermomechanical fields to deform and sinter ceramic powder compacts into complex-shaped ceramics. The shape-forming process hinges on: (1) the implementation of a precise thermal field to activate optimal deformability, and (2) the application of sufficient mechanical loads to guide deformation. We employ a programmable carbon-felt Joule heater that concurrently function as mechanical carriers, effectively transferring applied loads to the ceramic powder compacts. Using this ultrafast shaping and sintering (USS) method, we fabricate barium titanate (BT) piezoceramics in twisted shape, arch shape and with micropatterns. The USS method is energy-friendly (requiring approximately 1.06 kJ mm−3) and time-efficient (in several minutes level). Overall, the USS method offers an effective solution for shaping ceramics and extends them to 3D geometries with enhanced versatility.

Ultra-fast synthesis of transition metal-MXene nanocomposite electrocatalyst for energy-saving seawater hydrogen production: Experiment and theory

Switching from the urea oxidation reaction (UOR) to the oxygen evolution reaction (OER) is a beneficial way to lower the amount of energy needed to make hydrogen gas during the hydrogen evolution reaction (HER). Due to the sluggish reaction kinetics of the six electrons reaction of UOR, designing a privileged bifunctional electrocatalyst for both HER and UOR necessitates. The 2D nano-sized non-noble metal electrocatalysts make it possible to speed up reactions and improve their electrocatalytic performance. We synthesized nickel-cobalt-MXene composite nanosheets (NiCoMXene) on the surface of copper foam using a one-pot, simple, and ultra-fast electrochemical method. This 2D electrocatalyst demonstrates high electrocatalytic performance towards HER (overpotential of 76 mV at −10 mA cm−2) with excellent durability in alkaline media. Furthermore, NiCoMXene nanocomposite served as a bifunctional electrocatalyst to investigate hydrogen gas production by a hybrid system HER coupled with UOR in seawater. The NiCoMXene requires a low overpotential for HER (81 mV) and UOR (1.38 V) to achieve a current density of 10 mA cm−2 in seawater, and the needed cell voltage to reach the same current density is 1.42 V in seawater. Our DFT analysis found a significant synergy between MXene and NiCo in the electrocatalyst. PDOS analysis showed remarkably that introducing Ni atoms to MXene shifts the d-band center to the left (lower energy), while Co atoms shifts it to the right (higher energy) and increased states near the Fermi level. This electronic structure makes the nanocomposite an ideal electrocatalyst, with MXene providing electrons and Co atoms serving as active sites for both HER and UOR.This research work can provide a useful directive to explore the electrocatalysts with outstanding catalytic activity.

Method development and validation of an analytical quality by design ultrafast liquid chromatographic method for the determination of bedaquiline from pharmaceutical bulk and nanoemulsions.

Bedaquiline (BDQ) is a drug used to treat multidrug-resistant tuberculosis (MDR-TB). It exhibits exposure-dependent efficacy in eliminating Mycobacterium tuberculosis (Mtb). An easy, efficient and precise reverse-phase ultrafast liquid chromatography (RP-UFLC) method was developed to validate the free base of the antitubercular medication BDQ. BDQ was separated using a 10:90 v/v mobile phase of ammonium acetate buffer solution (pH = 5.4) and high-performance liquid chromatography-grade methanol, with a flow rate of 1.5mL/min and a UV detection wavelength of 226 nm. By using the Box-Behnken design (BBD) and response surface methodology (RSM), the method was optimised by varying critical analytical attributes (CAA) and critical performance attributes (CPAs) namely ammonium acetate fraction (%), flow rate (ml/min), buffer system molarity (M) and pH. BDQ was eluted at 7.5min utilising isocratic elution. The method was linear in the concentration range of 0.5-300 μg/mL with limit of detection values of 0.039 μg/mL and limit of quantification of 0.12 μg/mL. The results indicate that this validated method can be used as an alternative method for assay of BDQ.

Healing behavior of microcracks on the surface of yttria-stabilized polycrystals using an ultrafast high-temperature sintering method

A technique to heal microcracks on ceramic surfaces in a relatively short time is an attractive proposition for extending the lifetime of ceramics. To this end, we used the ultrafast high-temperature sintering (UHS) method, which permits a rapid temperature increase, to heal Vickers indentation microcracks generated in a 4 mol% Y2O3-doped ZrO2 polycrystal. We examined the microstructure following microcrack healing using transmission electron microscopy and scanning electron microscopy with continuous focused ion beam slicing along the microcrack plane. This revealed that the microcrack healing process involves crack pinching and neck formation, followed by the growth of the neck. The microcracks were fully healed at the surface by UHS treatment at 2000 °C for 20 s. However, residual pores corresponding to the unhealed state were observed inside the material. We hypothesized that these pore residues were caused by significant grain coarsening during UHS. It is essential to optimize the UHS temperature and time to account for grain coarsening and facilitate the application of this method to microcrack healing.

Exploring the performance of ammonia microfluidic fuel cell using PdNiCo aerogel

In this manuscript, PdNiCo and NiCo aerogel catalysts are prepared by an ultrafast sol-gel method combining microwave heating and freeze-drying. These new aerogels are synthesized to explore the transition metal content compared to a Pd aerogel in order to minimize the dependence on noble metals and improve their electrocatalytic properties in the presence of ammonia. The textural properties of the aerogels were characterized by the N2 adsorption/desorption isotherms. The crystal structures were measured by X-ray diffraction and X-ray photoelectron spectroscopy was used to analyze the electronic structures of the elements. The electrocatalytic activity of the aerogels towards the ammonia oxidation reaction was tested by cyclic voltammetry in a 1 M KOH + 1 M NH4OH solution. The combination of these properties in the PdNiCo and NiCo aerogels enhances the electrocatalytic activity of ammonium electro-oxidation compared to that of the Pd aerogel alone, and the multimetallic aerogels are more stable when used in a microfluidic device such as an ammonia fuel cell.

Gas-sensitive synergistic effect of Au-decorated ZnO nano-structured materials for rapid ethanol detection based on simulated sunlight activation

Local surface plasmon resonance (LSPR) and noble metal modification/doping are classical methods for improving the performance of metal-oxide-semiconductor (MOS)-based gas sensors. However, relatively less attention is paid to their synergies. In particular, research on synergistic gas-sensing technology that combines sunlight activation with other methods is significant for using friendly energy. In this study, Au-decorated ZnO (Au/ZnO) nano-structured materials (NMs) are successfully synthesised using a cost-effective nano-seed-assisted chemical bath and UV irradiation growth methods. The sensor based on this material exhibits superior performance in ethanol vapour under simulated sunlight, maintaining high sensitivity and repeatability at a low optimal working temperature. In particular, the sensitivity to 100 ppm of ethanol is 7.5 times better and the response time is 20 times shorter (tres < 1 s) in simulated sunlight than in the dark environment. The limit of detection (LOD) of ethanol is as low as 97 ppb, which is much lower than the concentration in exhaled breath of driving under the influence of alcohol according to Chinese law (20–80 ppm). This study provides a reliable and ultra-fast ethanol detection method, with potential applications in environmental monitoring and traffic safety. A possible gas-sensitive mechanism of the Au/ZnO ethanol vapour sensor is proposed based on the synergistic effect between simulated sunlight activation (LSPR, humidity resistance and thermal activation) and noble metal modification (electron sensitisation and chemical sensitisation). It provides a promising method for exploring the utilisation of sunlight for rapid gas detection.

Ultrafast Synthesis of MXenes in Minutes via Low-Temperature Molten Salt Etching.

Developing green and efficient preparation strategies is a persistent pursuit in the field of 2D transition metal nitrides and/or carbides (MXenes). Traditional etching methods, such as HF-based or high-temperature Lewis-acid-molten-salt etching route, require harsher etching conditions and exhibit lower preparation efficiency with limited scalability, severely constraining their commercial production and practical application. Here, an ultrafast low-temperature molten salt (LTMS) etching method is presented for the large-scale synthesis of diverse MXenes within minutes by employing NH4HF2 as the etchant. The increased thermal motion and improved diffusion of molten NH4HF2 molecules significantly expedite the etching process of MAX phases, thus achieving the preparation of Ti3C2Tx MXene in just 5minutes. The universality of the LTMS method renders it a valuable approach for the rapid synthesis of various MXenes, including V4C3Tx, Nb4C3Tx, Mo2TiC2Tx, and Mo2CTx. The LTMS method is easy to scale up and can yield more than 100g Ti3C2Tx in a single reaction. The obtained LTMS-MXene exhibits excellent electrochemical performance for supercapacitors, evidently proving the effectiveness of the LTMS method. This work provides an ultrafast, universal, and scalable LTMS etching method for the large-scale commercial production of MXenes.

Reinforced Magnetic-Responsive Electro-Ionic Artificial Muscles by 3D Laser-Induced Graphene Nano-Heterostructures.

Efficient ion transport and enriched responsive modals via modulating electrochemical properties of conductivity and capacitance are essential for soft electro-ionic actuators. However, cost-effective and straightforward approaches to achieve expedited fabrication of active electrode materials capable of multimodal-responsiveness remain limited. Herein, this work reports the one-step ultrafast laser direct patterning method, to readily synthesize electro- and magneto-active electrode material, derived from the unique cobalt-phosphorus co-doped core-shell heterostructures within 3D graphene frameworks, for fulfilling the dual-mode responsive electro-ionic actuators. The designed nanofiber-structured heterointerfaces across electrodes and electrolytes further promote highly efficient electron/ion transfer. The developed soft actuator exhibits superior actuation performance of peak-to-peak displacement to 13.08mm under an ultra-low ±0.5V, with doubled direct current deflection under 200 mT at 1V, an ultrafast response of 1.38 s and long-term stability (>90% retention for ≈106000 cycles), even detectable bending to ≈280µm under exceptional ±10mV. The promising demonstration of promoting differentiation and proliferation of stem cells under mechanical strain and electrical stimuli, sheds more light as well on the possibility of facilitating biomedical soft robotics with ultrahigh actuation performance.

Ultrafast synthesis of biphase Ni-doped FeOOH for efficient and stable oxygen evolution at high current density

NiFe oxyhydroxides, generally reconstructed on surface during oxygen evolution reaction (OER), are real active species for water oxidation; however, their direct and convenient preparation remains challenging. Here, we develop a one-step approach to prepare biphase (α/δ) Ni-doped FeOOH catalyst in 3 min under room temperature. The core of this ultrafast method is that Fe2+ derived from the redox reaction of Fe3+ and Ni2+ accelerate Fenton-like reaction, while simultaneously producing mixed-valence Ni ions(Ni2+, Ni3+) results in not only homovalent and heterovalent doping, but also biphase Ni-doped FeOOH heterojunction with high and low crystallinity. Specifically, Ni2+ doping leads to a preferred formation of low-crystalline δ-oriented Ni-doped FeOOH with abundant oxygen vacancies, which is in favor of triggering the lattice oxygen mechanism (LOM) during OER. Benefitting from high/low crystalline biphase heterojunction and LOM, the optimized Ni-FeOOH merely needs low overpotential of 300 mV to reach 1000 mA cm−2 for OER in alkaline electrolyte and also shows excellent durability even at a high current density of 500 mA cm−2. This work provides a cost-effective strategy to fabricate highly active and robust non-noble electrocatalysts that can potentially be applied for industrial-scale OER electrolysis.

Valley-selective manipulation of moiré excitons through optical Stark effect

Abstract Semiconductor moiré superlattices provide great platforms for exploring exotic collective excitations. Optical Stark effect, a shift of the electronic transition in the presence of light field, provides an ultrafast and coherent method of manipulating matter states, which, however, has not been demonstrated in moiré materials. Here, we report the valley-selective optical Stark effect of moiré excitons in the WSe2/WS2 superlattice by using transient reflection spectroscopy. Prominent valley-selective energy shifts up to 7.8 meV have been observed for moiré excitons, corresponding to pseudo-magnetic fields as large as 34 T. Our results provide a route to coherently manipulate exotic states in moiré superlattices.

Facile photopatterning of perfusable microchannels in hydrogels for microphysiological systems.

Perfusable hydrogels have garnered substantial attention in recent years for the fabrication of microphysiological systems. However, current methodologies to fabricate microchannels in hydrogel platforms involve sophisticated equipment and techniques, which hinder progress of the field. In this protocol, we present a cost-effective, simple, versatile and ultrafast method to create perfusable microchannels of complex shapes in photopolymerizable hydrogels. Our method uses one-step UV photocross-linking and a photomask printed on inexpensive transparent films, to photopattern both synthetic (PEG-norbornene) and natural (hyaluronic acid-norbornene) hydrogels in just 0.8 s. Moreover, these perfusable hydrogels are fully integrated into a custom-made microfluidic device that allows continuous fluid perfusion when connected to an external pump system. This methodology can be easily reproduced by professionals with basic laboratory skills and a fundamental knowledge of polymers and materials science. In this protocol, we demonstrate the functionality of our photopatterned hydrogels by seeding human endothelial cells into the microchannels, culturing them under dynamic conditions for 7 d, and exposing them to inflammatory stimuli to elicit cellular responses. This highlights the versatility of our platform in fabricating microphysiological systems and different microenvironments. The fabrication of perfusable channels within the hydrogels, including the fabrication of the microfluidic devices, requires ~3 d. The development of the cell-seeded microphysiological system, including the stimulation of cells, takes ~7 d. In conclusion, our approach provides a straightforward and widely applicable solution to simplify and reduce the cost of biofabrication techniques for developing functional in vitro models using perfusable three-dimensional hydrogels.

20 Seconds to fabricate high-performance NiFe-based anode for seawater electrolysis via bidirectional pulse current method

Direct electrolysis of seawater to produce green hydrogen has attracted great attention. While the development of efficient and rapid manufacturing processes for high-performance electrodes, particularly for the oxygen evolution reaction (OER), remains trail. Here, we introduce an innovative approach to fabricate high-performance NiFe-based OER electrodes using an ultrafast and eco-friendly bidirectional pulse current (BPC) method, which remarkably shortens the production time to only 20 s. Our BPC method alternates oxidation and reduction currents within a single period, promoting the in-situ formation of porous NiFe(oxy)hydroxide nanosheets through dissolution/deposition processes. Moreover, this methodology creatively utilizes the “Cl− induced effect”, typically a hindrance in other electrochemical systems involving seawater or brine, to enhance the synthesis of electrodes from NaCl-based electrolyte devoid of additional Ni/Fe cations. The prepared NiFe-based electrode (NFF O-R 20 s) demonstrates remarkable OER catalytic activity, with optimal overpotentials (ηj) of 272, 308 and 367 mV at current densities (j) of 10, 100 and 1000 mA cm−2, respectively. Impressively, it maintains a low cell voltage of 1.59 V after enduring 1000 h of operation under the industrially current density of 300 mA cm−2, with a direct current energy consumption of 3.8 kWh Nm−3 H2 for overall alkaline seawater electrolysis. Our BPC preparation approach provides a promising path to construction high-catalytic activity, good-stability electrode, and low-energy consumption direct seawater electrolyzer.

Estimation of polarity of slope of instantaneous current increment for power swing immune protection of series compensated line

Existing protection schemes for series-compensated transmission line (SCTL) lack either in reliability or speed during power swing (PS). A new ultra-fast reliable method is proposed in the present article using the slope of instantaneous current increment (SICI). The peaks of SICI (denoted by PKS) of a modal component of currents above a dynamic threshold are obtained to detect the sudden jump in SICI, which occurs after a transient disturbance. PKS of two terminal-currents are of same polarity for a fault within SCTL but they are of opposite polarity for any external event. This unique characteristic is mathematically verified and exploited to discern internal faults from external events during PS. Proposed method is found unaffected for high level of series compensation, position of compensation, close-in fault, fault inception point, high fault resistance, synchronization error and CT saturation. The results are finally compared to the incremental quantity-based methods to justify its merit.

Ultrafast and Chemoselective Biotinylation of Living Cell Surfaces for Time-Resolved Surfaceome Analysis.

Cell surface proteins participate in many important biological processes, such as cell-to-cell interaction, signal transduction, cell adhesion, and protein transportation. In-depth study of the cell surface protein group is of great significance. Nevertheless, detection and analysis of the surfaceome remain a significant challenge due to their low abundance and hydrophobicity. Herein, we reported an ultrafast and chemoselective labeling method using our newly developed trifunctional probe, the OPA-S-S-alkyne, which labeled cell surface lysine residues, and then established a novel cell surfaceome profiling approach. According to our experimental results, the OPA-S-S-alkyne probe can react extremely fast with living cells, labeling cells in only 1 min, while traditional NHS (labeling cell surface lysine with N-hydroxysuccinimide ester probe) and CSC (labeling cell surface glycan with hydrazide biotin probe) methods normally take longer time of more than 30 min and 1 h, respectively. Taking advantage of this ultrafast property of the method, we highlight the utility of this method by exploring the temporal dynamic changes of surfaceome upon EGF stimulation in living Hela cells and reported "early" and "late" EGF-regulated cell surface proteins, which are difficult to be distinguished by the current cell surface profiling approaches.

A high bonding tensile strength of CFRP ultrafast laser surface texturing method for surface damage repair

Carbon fiber reinforced polymer composite (CFRP) has a wide range of applications in aerospace, but it can cause varying degrees of damage in harsh service environments. Seeking a high-performance repair method is an effective way to save costs and ensure the service performance of CFRP components. In this study, a high bonding tensile strength of CFRP surface ultrafast laser texturing method for damage repair was proposed, which achieved complete removal of surface resin while retaining intact exposed fiber filaments. The difference in groove processing under unidirectional scanning and cross-scanning modes at different angles was explored. When the groove spacing was 0.2 mm and 0.4 mm, the surface resin was completely removed, the carbon fiber remained intact, and no debris was inside the groove. The groove morphology has a significant impact on the contact zone of the surface, which in turn affects the mechanical properties of the bonded joint. Cross-scanning can effectively improve surface roughness to increase the contact surface area. However, there is more fiber breakage, manifested as a groove weakening effect, which limits the improvement of bonding strength. In the 0° unidirectional scanning mode, the tensile performance of the joint is the best, improved by 61.6 % compared to manual processing.

Fabrication of Si3N4 ceramic balls by SPS method with SiC powder bed

AbstractSpark plasma sintering (SPS) is an ultrafast sintering method for the preparation of ceramics and ceramic composites with simple geometrical shapes, with the combined application of uniaxial pressure. This study aims to propose an SPS densification method for Si3N4 ceramic balls without necessitating alterations to tools and equipment. The Si3N4 ceramic balls intended for sintering are positioned within a SiC powder bed inside the conventional die used in SPS. The study systematically investigates the effects of presintering temperature (1400°C, 1500°C, and 1600°C) and SPS temperature (1600°C, 1700°C, and 1800°C) on the sphericity, relative density, phase composition, microstructure, and mechanical properties of Si3N4 ceramic balls. Experimental findings reveal that Si3N4 ceramic balls exhibiting an optimal combination of sphericity (0.94 ± 0.02), relative density (98.4%), and mechanical properties (Vickers hardness: 17.5 ± 0.4 GPa, fracture toughness: 6.4 ± 0.1 MPa·m1/2) were successfully achieved at a pre‐sintering temperature and SPS temperature of 1600°C, coupled with the use of a SiC powder bed and SPS method. Consequently, the SPS method demonstrates its capability to fabricate Si3N4 ceramic balls with excellent performance.

Ultrafast DNA detection based on turn-back loop primer-accelerated LAMP (TLAMP)

Rapid DNA detection is a long-pursuing goal in molecular detection, especially in combating infectious diseases. Loop-mediated isothermal amplification (LAMP) is a robust and prevailing DNA detection method in pathogen detection, which has been drawing broad interest in improving its performance. Herein, we reported a new strategy and developed a new LAMP variant named TLAMP with a superior amplification rate. In this strategy, the turn-back loop primers (TLPs) were devised by ingeniously extending the 5’ end of the original loop primer, which conferred the new role of being the inner primer for TLPs while retaining its original function as the loop primer. In theory, based on the bifunctional TLPs, a total of eight basic dumbbell-like structures and four cyclic amplification pathways were produced to significantly enhance the amplification efficiency of TLAMP. With the enhancing effect of TLPs, TLAMP exhibited a significantly reduced amplification-to-result time compared to the conventional six-primer LAMP (typically 1 h), enabling rapid DNA detection within 20 min. Furthermore, TLAMP proved to be about 10 min faster than the fast LAMP variants reported so far, while still presenting comparable sensitivity and higher repeatability. Finally, TLAMP successfully achieved an ultrafast diagnosis of Monkeypox virus (MPXV), capable of detecting as few as 10 copies (0.67copies/μL) of pseudovirus within 20 min using real-time fluorescence assay or within 30 min using a colorimetric assay, suggesting that the proposed TLAMP offers a sensitive, specific, reliable, and, most importantly, ultrafast DNA detection method when facing the challenges posed by infectious diseases.

Applications and state-of-the-art review of pulsed laser ultrafast time-resolution method in the field of rock mechanics

Applications and state-of-the-art review of pulsed laser ultrafast time-resolution method in the field of rock mechanics

Analysis of omarigliptin forced degradation products by ultra-fast liquid chromatography, mass spectrometry, and in vitro toxicity assay.

Omarigliptin (OMG) is an antidiabetic drug indicated for the treatment of type 2 diabetes mellitus. Forced degradation studies are practical experiments to evaluate the stability of drugs and to establish degradation profiles. Herein, we present the investigation of the degradation products (DPs) of OMG formed under various stress conditions. OMG was subjected to hydrolytic (alkaline and acidic), oxidative, thermal, and photolytic forced degradation. A stability-indicating ultra-fast liquid chromatography method was applied to separate and quantify OMG and its DPs. Five DPs were adequately separated and detected in less than 6 min, while other published methods detected four DPs. MS was applied to identify and obtain information on the structural elucidation of the DPs. Three m/z DPs confirmed previously published research, and two novel DPs were described in this paper. The toxicity of OMG and its DPs were investigated for the first time using in vitro cytotoxicity assays, and the sample under oxidative conditions presented significant cytotoxicity. Based on the results from forced degradation studies, OMG was found to be labile to hydrolysis, oxidation, photolytic, and thermal stress conditions. The results of this study contribute to the quality control and stability profile of OMG.