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Most existing secure biometric authentication schemes are server-centric, and users must fully trust the server to store, process, and manage their biometric data. As a result, users’ biometric data could be leaked by outside attackers or the service provider itself. This paper first constructs the EDZKP protocol based on the inner product, which proves whether the secret value is the Euclidean distance of the secret vectors. Then, combined with the Cuproof protocol, we propose a novel user-centric biometric authentication scheme called BAZKP. In this scheme, all the biometric data remain encrypted during authentication phase, so the server will never see them directly. Meanwhile, the server can determine whether the Euclidean distance of two secret vectors is within a pre-defined threshold by calculation. Security analysis shows BAZKP satisfies completeness, soundness, and zero-knowledge. Based on BAZKP, we propose a privacy-preserving biometric authentication system, and its evaluation demonstrates that it provides reliable and secure authentication.

Superamphiphobic and flame-retardant fabrics offer effective protection for firefighters and industrial workers operating under hazardous conditions. However, limitations in deformation resistance, wear comfort, and environmental adaptability hinder their practical applications. Here, a monolithic hierarchical macro-/micro-/nanostructure is constructed to achieve durable repellency against water and oils, even under significant deformations. This coating integrates fluorinated nanoparticles, flame retardant microparticles, and a cross-linking adhesive. Hydrogen bonding and the adhesive define the coating’s morphology, robustness, and adaptability. The coated surface exhibits an ultralow water adhesion force (0.002 mN) and excellent anti-fouling performance against extreme temperatures (100 °C, −196 °C) and corrosive liquids, including aqua regia and concentrated H 2 SO 4 . Upon fire exposure, the coating enables self-extinguishing behavior on cotton fabrics. The coated fabrics also demonstrate remarkable mechanical and UV resistance while preserving wear comfort. Overall, we achieve a balance between desirable properties and wear comfort in superamphiphobic, flame-retardant fabrics, enabling protective clothing applications previously unattainable. Integrating superamphiphobicity, flame retardancy, mechanochemical robustness, and environmental adaptability into a single coating remains challenging. Here, the authors present a scalable strategy that achieves these features, enabling previously unattainable protective clothing applications.

To meet the increasing demand for wire electrical discharge machining (WEDM) under extreme conditions such as ultra-high thickness cutting, micro-wire cutting, micro-energy finishing, and ceramic composites machining, a concept of multichannel discharge WEDM under semiconductor characteristics was proposed. The essence of this conception is that under these extreme machining conditions, the electrode wire or workpiece — or even both of the two electrodes — cannot be treated as electrically conductive materials of the conventional WEDM due to their high electrical resistance. However, they can exhibit electrical discharge behavior like semiconductors, which is defined as semiconductor characteristics. The conventional WEDM theory and related technologies cannot be applied to extreme WEDM because conventional WEDM only has one discharge channel per pulse, whereas multiple discharge channels can be generated by each pulse in extreme WEDM. Therefore, a suitable theory needs to be developed for extreme WEDM under semiconductor characteristics. Based on the multichannel discharge behavior of semiconductors, experiments were conducted on high-efficiency machining with multichannel discharge by stacking several workpieces as an assembly with semiconductor characteristics. It was proved that the multichannel discharge WEDM is capable of achieving high machining efficiency, as well as enhanced surface quality and lower wear of electrode wire. The proposed multichannel discharge WEDM sets up the foundation for the establishment of the theoretical system of EDM under semiconductor characteristics.

The fabrication of epoxy/graphene composites with greatly enhanced thermal conductivity ( K ) in terms of efficient thermal dissipation of electronic devices has drawn much interest. However, the lack of continuous thermal conductive paths and thermal interface resistances generated between matrix and fillers limit the further enhancement of the K value. Here, a siloxane cross-linked graphene framework (SGF) with highly conductive paths is prepared by a simple way, i.e. , thermal-shock exfoliation of graphene oxide film followed by self-polymerization of silanol inside GF. The epoxy (EP) resin was then impregnated into SGF to form the EP/SCF composite. The mutual percolation of EP and SGF in the composite eliminates the distribution issue of graphene sheets. The siloxane molecular network not only cross-links adjacent graphene sheets, but also forms chemical bonding with EP matrix, resulting in significantly decreased inter-sheet and interface thermal resistances. The EP/SGF composite containing 20.2 wt% graphene exhibits an in-plane K of 54.2 W m –1  K –1 , which is about twice higher than that of EP/GF without siloxane and 270 times higher than pure EP. Graphical Abstract

The critical heat flux (CHF) of minichannel heat sinks is crucial, as it helps prevent thermal safety incidents and equipment failure. However, the underlying mechanisms of CHF in minichannels remain poorly understood, and existing CHF prediction models require further refinement. This study systematically investigates the characteristics and influencing factors of critical heat flux (CHF) in rectangular minichannels through combined experimental and theoretical approaches. Experiments were conducted using microchannels with hydraulic diameters ranging from 0.5 to 2.0 mm, with ethanol employed as the working fluid. Key parameters-including mass flux, channel geometry, system pressure, and inlet subcooling-were analyzed to assess their influence on CHF. Results indicate that CHF increases with mass flux; however, the increase rate diminishes under higher mass flux. Larger channel dimensions significantly enhance CHF by delaying liquid film dryout. System pressure further improves CHF by reducing bubble detachment frequency and promoting flow stability. Increased inlet subcooling enhances CHF by delaying the onset of nucleate boiling and improving convective heat transfer. Four classical CHF prediction models were evaluated, revealing significant overprediction-up to 148.69% mean absolute error (MAE)-particularly for channels with hydraulic diameters below 1.0 mm. An ANN deep learning model was developed, achieving a reduced MAE of 8.93%, with 93% of predictions falling within ±15% error. This study offers valuable insights and a robust predictive model for optimizing microchannel heat sink performance in high heat flux applications.

Ecofriendly green biosynthesis of bacterial cellulose (BC) using a low-cost carbon source from the shell extract of Sapindus mukorossi was studied by Komagataeibacter xylinus B2-1. After 7 d of incubation, strain B2-1 produced 1.31 g L−1 BC, which had similar micro-morphology and structural properties to that from Hestrin–Schramm medium based on scanning electron microscopy, X-ray diffraction and Fourier transform infrared analyses. While strain B2-1 grew well and produced BC efficiently at pHs ranging from 4.0 to 6.0, the considerable BC production was only found at temperature of 30 °C. The present investigation can provide a new low-cost carbon source for BC preparation and lead towards commercialization and industrial scale up BC.Graphic abstract

Severe uneven wire tension occurs during super-high-thickness (more than 1000 mm) cutting in high-speed wire electrical discharge machining, resulting in different discharge regularities between electrodes when the wire electrode is in the positive and negative traveling directions. Regarding the specific performance, a certain proportion of no-load pulses will appear between electrodes when the wire electrode is in the positive traveling direction, resulting in the feeding of the machine tool; when the wire electrode is in a negative traveling direction after feeding, a large number of short-circuit pulses will be formed, which seriously affect the continuous and stable feeding and the cutting speed. According to these different regularities, this work proposes the use of different reference objects as the basis of servo feeding in the positive and negative traveling directions. A pulse probability detection servo control method based on the discharge peak current is designed, and different control objects for the positive and negative traveling direction are used as the target probabilities of the proportional integral derivative algorithm. The results of experiments demonstrate that the proposed servo control method can significantly improve the cutting stability and cutting speed for super-high-thickness cutting. When cutting a workpiece with a thickness of 1000 mm, the surface machined by the average voltage detection-based servo method with the fixed threshold and the conventional pulse probability-based servo control method was found to exhibit obvious streaks, and the cutting speed was respectively 53.75 mm 2 /min and 63.6 mm 2 /min. Finally, the surface machined by the proposed servo control method was even, and the cutting speed was 77.78 mm 2 /min, thereby exhibiting an improvement of 44.71% as compared to that of the average voltage detection method with a fixed threshold, and the surface evenness was greatly improved. Thus, the proposed servo control method for super-high- thickness cutting was found to achieve a faster cutting speed and higher surface quality.

The electrical resistance of wire electrode increases with the decrease of the wire diameter. It is difficult to use the voltage threshold method to distinguish the spark and short-circuit states according to the discharge voltage, so it cannot meet the requirements of normal machining. In this study, a gap discharge state identification and servo control method based on discharge current are proposed in high-speed reciprocating microwire-EDM. The synchronous pulse can improve the stability of the system by reducing the disturbance of the discharge frequency and deionization. The experimental results show that a high wire speed is beneficial to the introduction of dielectric and the removal of erosion particles. When the target probability is set at 90%, the processing stability is higher. By using Φ 0.08 mm molybdenum wire electrode, the stable cutting of a 1250 height-diameter ratio (the ratio of cutting height to electrode wire diameter) workpiece is realized with an average cutting efficiency of 32.08 mm 2 /min. This study is a useful exploration of the machining of high height-diameter ratio workpieces by using a microwire electrode in high-speed wire-cut electrical discharge machining (HSWEDM).

Several studies have demonstrated that exosomes (Exos) are involved in the regulation of macrophage polarization and osteoclast differentiation. However, the characteristics as well as roles of exosomes from human periodontal ligament cells (hPDLCs-Exos) in M1/M2 macrophage polarization and osteoclast differentiation remain unclear. Here, periodontal ligament cells were successfully extracted by method of improved Type-I collagen enzyme digestion. hPDLCs-Exos were extracted by ultracentrifugation. hPDLCs-Exos were identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting (WB). Osteoclast differentiation was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), WB and tartrate-resistant acid phosphatase (TRAP) staining. M1/M2 macrophage polarization were evaluated by RT-qPCR and WB. The results showed hPDLCs-Exos promoted osteoclast differentiation and M2 macrophage polarization, but inhibited M1 macrophage polarization. Moreover, M1 macrophages inhibited osteoclast differentiation, whereas M2 macrophages promoted osteoclast differentiation. It has shown that hPDLCs-Exos promoted osteoclast differentiation by inhibiting M1 and promoting M2 macrophage polarization.

Surface machined by high-speed wire electrical discharge machining (HS-WEDM) at super-high thickness (more than 1000 mm) cutting suffers from uneven surface, a major problem that has been investigated in this paper. According to the analysis, as wire frame span increases, the rigidity of the wire electrode decreases, and under the action of discharge explosive force, wire electrode vibration intensifies. As a result, the machining stability inevitably decreases. However, the core problem is whether there is enough working fluid in the slit to dampen and absorb the vibration of the wire electrode so as to ensure the positional stability of the wire electrode. To verify the above point of view: first, the wire guide and gravity take-up with bidirectional tension in the wire feeding system were installed to improve the positional accuracy of the wire electrode; second, to improve the flow of the working fluid into the slit, the slit width was increased by improving the working fluid and a medium carrier with a higher melting point and vaporization point can reduce the vaporization of the working fluid in the slit as much as possible. The experiment showed that the outlet flow of the improved working fluid is 56.72% higher than that of the original working fluid when cutting a 750-mm thick workpiece, which increases the damping and vibration absorption effect of the working fluid on the wire electrode in the long and narrow gap. After the above measures were implemented, super-high thickness cutting can be carried out continuously and steadily, the surface evenness was significantly improved, and the workpiece with a thickness of 2000 mm was cut successfully.