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This study proposes an effective fabrication method for creating a hierarchical micro/nano structured aluminum alloy surface to enhance its hydrophobicity through single point diamond cutting using magnetophoresis. Magnetophoresis is a technique that manipulates metallic particles in metallic fluids using magnetic fields, and this study applies it to single-point diamond cutting by incorporating permanent magnets into the machining setup. The main grooves are cut to create a nano-grooved pattern on the first layer of the surface, while secondary grooves are cut on top of the first layer to form a micro pattern on the surface for two samples, one with and one without magnetophoresis. For magnetophoresis-fabricated samples, the first and second layers are cut in the presence of a magnetic field that is oriented perpendicular to the cutting direction of the first layer. Atomic force microscopy and an optical surface profiler reveal that the metallic marks appear on the surfaces that are parallel to the applied magnetic field for the magnetophoresis sample, which have been integrated with nano grooves to form a nano-textured surface on top of the microstructures. The sample fabricated under the influence of a magnetic field with magnetophoresis exhibits improved surface hydrophobicity, quality, and durability. This study highlights that magnetophoresis has the potential to fabricate metallic hydrophobic surfaces more efficiently than traditional methods for hierarchical micro/nano structured metallic surfaces, given that it does not necessitate the use of complex machining systems or advanced equipment.

This study focuses on the application of in-situ laser-assisted single-point diamond turning (ILAT) on SiCp/Al metal matrix composites (MMCs), renowned for their exceptional mechanical properties and difficult-to-cut nature. The surface and subsurface response to the in-situ laser assistance under a small uncut chip thickness (UCT) is investigated. The results demonstrate that appropriate laser energy can reduce subsurface crystal defects while maintaining surface quality during machining. As the laser power increases, the surface damage pattern shifts from cut-through to fracture, eventually leading to severe matrix deformation. Slight compressive stress is observed on the Al phase of surfaces machined with either conventional single-point diamond turning (SPDT) or ILAT. Al crystals near the machined surface and SiC particles in the SPDT sample exhibit a notable accumulation of dislocations. Laser assistance is beneficial for mitigating dislocations and improving the crystalline integrity of Al grains, while Al grains close to the machined surface in both SPDT and ILAT samples present comparable amounts of stacking faults. The findings enhance the understanding of surface and subsurface generation of SiCp/Al composites in ILAT, providing a reference for the application of ILAT on other MMCs.

The primary objective of this study is the development of Cu/Nb composite materials for Superconducting Radio-Frequency (SRF) applications under extreme service conditions characterized by a strong RF electromagnetic field, extremely low temperatures, and relatively low heat loss. A novel integrated manufacturing approach is proposed, which combines cold-sprayed AgCuTi alloy as an intermediate coating on the Nb surface and an electroplated Cu layer with a subsequent heat treatment brazing effect. This strategy aims to address the significant challenge of non-intermelting Cu and Nb while also considering effective lateral heat transfer. Mechanical property tests showed that the bond strength of Nb/AgCuTi/Cu composites exceeded 150 MPa. Low-temperature thermal transport tests indicate that the Residual Resistance Ratio (RRR) of the Cu layer surpasses 150, with a thermal conductivity at 4.2 K exceeding 1600 W/(m·K). Moreover, both the composite interface and mechanical properties of the specimens remain stable even after undergoing cyclic cold shock experiments. These findings suggest that the Nb/AgCuTi/Cu composite material developed in this study meets the technical requirements for long-term stable and high-performance operation in high-current and high-power superconducting accelerators.

High-entropy alloys, as the novel multi-principal alloys composed of five or more elements in equal-atomic ratios or near-equal atomic ratios, are widespread in extreme environments, including high-temperature, high-dynamic loading, and high-irradiation. However, how to improve their machinability still faces challenges because of their high hardness and wear resistance. To solve this problem, this paper proposes an in-situ laser-assisted diamond turning process. Experimental results show the machinability of the high-entropy alloy CoCrFeMnNi is obviously improved. The average value of the surface roughness Sa of the machined sample reaches 2 nm. Compared with the traditional single-point diamond turning, the surface quality is improved by 33.3 %, demonstrating the effectiveness of the proposed machining method. Tool wear also decreases by above 35 %, again demonstrating the superiority of the proposed machining method. Besides, the effect of the machining on the crystalline structure is also analyzed. Therefore, this study provides an efficient and simple approach for enhancing the machinability of the high-entropy alloy CoCrFeMnNi, which can be applied in industrial production in the future.

Nickel-titanium (NiTi) alloy has unique functional properties in medical and microelectronics products. Recently, additive manufacturing has become an attractive way of fabricating NiTi alloy. However, the study of generating microstructure arrays on additively manufactured (AMed) NiTi alloy surfaces remains unclear. Motivated by this, this study proposes the ultraprecision micro-milling (UMM) process to generate microstructure arrays and perform a systematic investigation. First, selective laser melting, as a popular additive manufacturing way, was utilized to fabricate the AMed NiTi alloy. Then, the UMM process was carried out to machine these samples. After the machining experiments, a mirror surface with a surface roughness of 0.014 μm can be acquired, which demonstrates the good machinability of the AMed NiTi alloy. Moreover, the micro-groove array and micro-pillar array with low machining errors were machined on the AMed NiTi alloy surfaces, which verifies the effectiveness of the proposed machining process. The corresponding cutting forces, tool conditions, and chip morphologies were studied to fully understand the machining mechanism of the AMed NiTi alloy. Besides, the surface wettability of microstructure arrays was also quantitatively analyzed. Therefore, this study provides a facile and effective machining process for generating microstructure arrays on the AMed NiTi alloy surfaces.

We have conducted a study that focuses on designing a quasi-1D ultrathin and long ferromagnetic nanowires array with excellent linearity. The purpose of this design is to test the presence of Majorana zero modes in pairs over a long distance and the influence of the lateral interaction. Specifically, we investigate the magnetic properties of a one-unit cell thick MoSX nanowire array, where dopant X (H, C, N, O, and F. etc) is utilized, to assess its suitability for our intended purposes. Our findings reveal that the edge magnetization of the optimized MoSX nanowires is comparable to that of 3d transition metals with the Curie transition temperature surpassing room temperature. Our study indicates that the ferromagnetism of the optimized MoSX nanowires is unlikely to be eliminated when placed on an s-wave superconductor due to lattice mismatch. By conducting comparative case studies of various dopants, we establish a connection between the source of magnetism in the nanowires and internal electric fields, charge perturbation, spin-orbital coupling and p-d hybridization. The strong exchange interaction, robust spin-orbital coupling and large local magnetic moment exhibited by long and ultrathin room-temperature ferromagnetic nanowires open up avenues for diverse topological applications.

Abstract The high hardness, brittleness, and thermal resistance impose significant challenges in the scalable manufacturing of fused silica lenses, which are widely used in numerous applications. Taking advantage of the nanocomposites by stirring silica nanopowders with photocurable resins, the newly emerged low‐temperature pre‐shaping technique provides a paradigm shift in fabricating transparent fused silica components. However, preparing the silica slurry and carefully evaporating the organics may significantly increase the process complexity and decrease the manufacturing efficiency for the nanocomposite‐based technique. By directly pressing pure silica nanopowders against the complex‐shaped metal molds in minutes, this work reports an entirely different room‐temperature molding method capable of mass replication of complex‐shaped silica lenses without organic additives. After sintering the replicated lenses, fully transparent fused silica lenses with spherical, arrayed, and freeform patterns are generated with nanometric surface roughness and well‐reserved mold shapes, demonstrating a scalable and cost‐effective route surpassing the current techniques for the manufacturing of high‐quality fused silica lenses.

The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications. However, micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition. Motivated by this, this study proposed a machining process, named the ultraprecision diamond surface texturing process, to machine the micro/nanostructures on magnesium alloy surfaces. Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces, demonstrating the effectiveness of this proposed machining process. Furthermore, sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces. The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces. The corresponding cutting force, chip morphology, and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces. The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields, such as optics.

Background Virtual reality is a relatively new intervention that has the potential to be used in the treatment of eye and vision problems. This article reviews the use of virtual reality-related interventions in amblyopia, strabismus, and myopia research. Methods Sources covered in the review included 48 peer-reviewed research published between January 2000 and January 2023 from five electronic databases (ACM Digital Library, IEEE Xplore, PubMed, ScienceDirect and Web of Science). To prevent any missing relevant articles, the keywords, and terms used in the search included “VR”, “virtual reality”, “amblyopia”, “strabismus,” and “myopia”. Quality assessment and data extraction were performed independently by two authors to form a narrative synthesis to summarize findings from the included research. Results Total number of 48 references were reviewed. There were 31 studies published on amblyopia, 18 on strabismus, and 6 on myopia, with 7 studies overlapping amblyopia and strabismus. In terms of technology, smartphone-based virtual reality headset viewers were utilized more often in amblyopia research, but commercial standalone virtual reality headsets were used more frequently in myopia and strabismus-related research. The software and virtual environment were mostly developed based on vision therapy and dichoptic training paradigms. Conclusion It has been suggested that virtual reality technology offers a potentially effective tool for amblyopia, strabismus, and myopia studies. Nonetheless, a variety of factors, especially the virtual environment and systems employed in the data presented, must be explored before determining whether virtual reality can be effectively applied in clinical settings. This review is significant as the technology in virtual reality software and application design features have been investigated and considered for future reference.

Cadmium telluride (CdTe) is known as an important semiconductor material with favorable physical properties. However, as a soft-brittle material, the fabrication of high-quality surfaces on CdTe is quite challenging. To improve the fundamental understanding of the nanoscale deformation mechanisms of CdTe, in this paper, MD simulation was performed to explore the nano-grinding process of CdTe with consideration of the effects of grain size and grinding depth. The simulation results indicate that during nano-grinding, the dominant grinding mechanism could switch from elastic deformation to ploughing, and then cutting as the grinding depth increases. It was observed that the critical relative grain sharpness (RGS) for the transition from ploughing to cutting is greatly influenced by the grain size. Furthermore, as the grinding depth increases, the dominant subsurface damage mechanism could switch from surface friction into slip motion along the directions. Meanwhile, as the grain size increases, less friction-induced damage is generated in the subsurface workpiece, and more dislocations are formed near the machined groove. Moreover, regardless of the grain size, it was observed that the generation of dislocation is more apparent as the dominant grinding mechanism becomes ploughing and cutting.

Micro/nanostructure arrays have been broadly applied in numerous industrial fields, such as optics, antibacterial fields, and anti-corrosion. However, the highly efficient fabrication of micro/nanostructure arrays, especially the high-aspect-ratio and hierarchical micro/nanostructure arrays, remains a challenge. Motivated by this, the study designs a novel piezoelectrically actuated (PA) cutting system for fabricating this kind of micro/nanostructure array. First, the mechanical structure of the PA cutting system is designed based on the circular flexure hinge. Then, a finite element model is established to analyze its resonant frequencies and mode shapes. Next, to determine the working performances of the PA cutting system, a performance test platform is built. Finally, various micro/nanostructure arrays with two features of the high-aspect-ratio and the multilayer are fabricated, demonstrating the effectiveness and flexibility of the PA cutting system. Besides, the function of machined micro/nanostructure arrays about the corrosion property was investigated. This study provides a new approach for fabricating high-aspect-ratio and hierarchical micro/nanostructure arrays, which can be applied in industrial manufacturing and corrosion protection fields.

In ultra-precision cutting, the inherent working frequency and positioning accuracy of actuators are decisive. It is challenging to generate multi-scale cutting motions with high accuracy on hierarchical scale simultaneously. In this study, a novel micro and nano-cutting device with complex-axis is developed, consisting of a customized designed linear voice coil motor and a piezoelectric actuated flexure-hinge mechanism to generate micro and nano-cutting motions, respectively, for overcoming the challenge. The structure of the cutting device is designed with a small form factor in dimension in comparison to other auxiliary cutting devices for ultra-precision machine tools. The magnetic field simulation is also used to optimize the output force of the voice coil motor with the simulation results validated by experiments using a force sensor. The operation mechanism of the flexure-hinge is investigated by finite element analysis. The device can perform ± 0.5 mm stroke at 10 Hz and ± 8 µm at 3300 Hz for generation of microstructures with experimental validation. The significance and originality of this study lie in the successful development of a novel hybrid actuation cutting system that can generate multi-scale cutting motions with high accuracy and flexibility on a hierarchical scale for the generation of microstructured surfaces in ultraprecision machining.

Metallic materials have long been used in a wide range of industrial applications due to their outstanding physical and mechanical properties as well as high process latitudes. Mechanical machining is one of the important steps in manufacturing of metallic components because it directly influences the surface quality of the final products. To date, extensive studies have been conducted on the investigation of factors affecting the machinability of metallic materials, such as cutting parameters, cooling conditions and material micro/nanostructures. Contributory factors of cutting parameters and cooling conditions have been extensively reviewed in previous studies, but there is still a lack of a fundamental review to clearly understand the effects of material micro/nanostructures on the machining. Therefore, this review highlights the influences of different micro/nanostructures on the machinability and discusses the materials deformation mechanism in machining of metallic materials. The micro/nanostructures mainly include crystalline anisotropies of single crystals, grain sizes of polycrystals, phase compositions of single/multiphase materials, layer-by-layer structures of additive manufactured materials, amorphous structures of bulk metal glasses, micro reinforcements of metal matrix composites, and porosities of porous metal foams. Besides, the challenges and opportunities faced in machining of metallic materials are discussed from the perspective of micro/nanostructures.

The fabrication of micro/nanostructure arrays on nickel or nickel alloy surfaces is still a challenge because of the high hardness and low thermal conductivity. Motivated by this, this study proposed the ultraprecision tool-servo cutting process to fabricate micro/nanostructure arrays on the nickel surfaces. Experimental results showed the micro-lens array and sawtooth-shaped nanostructure array were successfully fabricated on pure nickel surfaces. The fabrication error of the micro-lens array is

This paper presents the nonlinear analysis of stability and dynamic rotational accuracy of an unbalanced rotor supported by aerostatic journal bearings. A finite element method is utilized with the Runge-Kutta fourth order method to solve the transient Reynolds equation and the rotor dynamics equations simultaneously for the dynamic response analysis of the rotor. The dynamic behavior of the rotor center is analyzed under different rotor masses. It is shown that the dynamic responses of the rotor strongly depend on the rotor mass. The periodic, multi-periodic or quasi-periodic motions are observed as the rotor mass changes. Under a given operating speed, the mass at which the resonance occurs is studied and its relationship with the mass of the rotor at the threshold of instability is found for the first time. The influences of supply pressure, bearing clearance, orifice diameter and eccentric distance on the rotational accuracy, the resonance and instability threshold are also investigated. The result of this study can provide guidance for designing aerostatic bearing rotor systems with required running accuracy and stability.

The bullwhip effect refers to the phenomenon of the increase in demand variability from supply chain downstream members to upstream members. This effect is critically important for the different sectors involved in a supply chain and is one of the main causes of inefficiency, material waste, and low sustainability in supply chain management. In order to help minimize the bullwhip effect and achieve sustainable development in a supply chain, this study identifies the influential factors of the bullwhip effect in a supply chain and the interactive relationships among them. A bi-level bullwhip effect analysis model was established to evaluate the causes of the bullwhip effect at different levels by using a social network analysis approach. Furthermore, to help achieve efficient and sustainable development, the implications of mitigating the impacts of the bullwhip effect in a supply chain were explored based on the results of the inter-relationships analysis among the contributing factors of the bullwhip effect.

In this study, in order to improve and restore the performance of the polishing pads and reduce the cost of chemical mechanical polishing, three types of material polishing pads, namely, polyurethane, damping cloth, and non-woven fabric, were selected for the experiment. Accordingly, each polishing pad was set up with diamond conditioner and high-pressure micro-jet (HPMJ) conditioning control experiments. Subsequently, the fluctuation ranges of the material removal rate on the three polishing pads were 2.73–3.75 μm/h, 1.38–1.99 μm/h, and 2.36–4.32 μm/h, respectively under the HPMJ conditioning method, while the fluctuation ranges of the material removal rate on the three polishing pads were 1.80–4.14 μm/h, 1.02–2.09 μm/h, and 1.78–5.88 μm/h under the diamond conditioning method. Comparing the polishing pad morphologies under SEM, we observed that the surface of the polishing pad after HPMJ conditioning was relatively clean, and the hole structure was not blocked. Contrastingly, there remained numerous abrasive particles on the surface after the conventional diamond conditioning and the hole structure was blocked. Thus, the HPMJ conditioning technology is better than the traditional diamond conditioning technology. Subsequently, the polishing pad after HPMJ conditioning has a longer service life and a more stable material removal rate than that after traditional diamond conditioning.

Titanium alloy is one of the most important metals widely used in many industrial fields due to its special performance, such as high corrosion resistance and specific-strength. In recent years, titanium alloy has a great application prospect in the optical field. However, the pitiful machinability of titanium alloy material brings great difficulty to its ultra-precision cutting. In this paper, we have proposed the method of ultrasonic-assisted ultra-precision turning (UAUT) to improve the cutting performance of titanium alloy. In addition to exploring the mechanism of ultrasonic cutting, the purpose of this paper is to make a comprehensive comparison between UAUT and conventional ultra-precision turning (CUT) of Ti6Al4V alloy. The orthogonal cutting model was established using the software ABAQUS for revealing the cutting mechanism of titanium alloy. The effect of ultrasonic vibration on the chip morphology, cutting force, residual stress, and cutting temperature in the ultra-precision turning process of titanium alloy has been investigated by the finite-element model. The results of the simulation indicate that UAUT can reduce the cutting force, residual stress, and temperature as compared to that in CUT. The results of the simulation show a great agreement with the experimental results. Furthermore, the comparison of surface roughness and surface morphology between the UAUT and CUT experiments confirmed that the surface quality of the Ti6Al4V sample is improved obviously by ultrasonic vibration. At the same time, the results of the experiments show that the chips became more continuous, and the tool wear was reduced by the UAUT method. This research proved that the UAUT method can greatly improve the cutting performance of titanium alloy.

Ultra-precision diamond cutting (UPDC) is a promising machining technology to generate precise components with optical grade surface. However, a tool rake angle turns to be negative when the tool radius is significantly larger than cutting depth during UPDC. The resulted plowing motion, which is the well-known size effect, causes undeformed and uncut materials remaining on the machined surface and thus affects the surface integrity of final components. In this study, the tribology behavior of tool/workpiece was altered in order to resolve the problematic size effect. A magnetic field was superimposed into titanium alloys during UPDC to increase the friction coefficient at the tool/workpiece interface in order to minimize the size effect and reduce minimum chip thickness (MCT) in UPDC. The experimental results showed the friction coefficient at the tool/workpiece interface increased under the magnetic field influence and a better surface quality was achieved in the presence of magnetic field. MCT of titanium alloys was reduced to 1μm by utilizing the proposed machining technology which the reduction percentage reached to 50%. A lower MCT value means the feasibility of machining under smaller depth of cut and thus enhances the existing precise level of components fabricated in ultra-precision machining.

ESL writing teachers face the challenge of providing written feedback that is both effective and motivating to students. Thus, many end up making use of praise (or positive feedback) before offering criticism. Only limited research has examined how students perceive praise, and few studies among the most recent have focused on praise above other types of feedback. Moreover, researchers have not accounted for the effect of person-focused vs. performance-focused praise. We developed an original survey to understand how L2 learners perceive and value person and performance praise in written feedback. A total of 106 adult participants from two language groups (Asian and Romance) and at two English ability levels (intermediate and advanced) rated six different samples of praise based on how clear, helpful, valuable, encouraging to revision, kind, and motivating they found praise comments to be. Ultimately, praise type appeared to be the most significant variable as participants showed preference to performance over person praise. These results can be useful for teachers as they consider how to word statements of praise, particularly in response to student writing.

Aluminum alloy 6061(Al6061), an Al-Mg-Si alloy, is a precipitation-hardened alloy. The generation of precipitate affects its mechanical properties, and induces a worse surface finish during diamond cutting. The friction coefficients of the tool-chip and tool-workpiece interfaces influence temperature rise, and are therefore important predictors of tool wear and surface integrity during the diamond cutting of Al6061. This study investigated the relationship between precipitate generation and the friction coefficients of Al6061. Groups of experiments were conducted to study the influence of temperature and heating time on the number of precipitates and the friction coefficients. The results show that the generation of AlFeSi particles induces cracks, scratch marks and pits on diamond-machined Al6061 and affects the cutting forces. Moreover, the variation trend of the friction coefficient of Al6061 under different heating conditions agrees well with that of the number of AlFeSi particles. This implies that, during ultra-precision machining of precipitation-hardened alloys, cutting-induced heat causes precipitates to form on the chips and machined surface, changing their material properties. This affects the tool-workpiece and tool−chip contact conditions and the mechanisms of chip formation and surface generation in ultra-precision machining.

The material swelling effect in single point diamond turning (SPDT) causes ragged materials on a machined surface which slows down the movements of tool tip vibration, and acts as a simple impacted pendulum system with a damping effect and displays a single twin peak in fast Fourier transform (FFT). Due to the low elastic modulus and low thermal conductivity of titanium alloys, the material swelling effect of titanium alloys in SPDT is much more serious than that of traditional metals. For this reason, the tool tip vibration in SPDT of titanium alloys is expected to be different from previous reports. In this study, apart from the demonstration of the original single twin peak induced from the material swelling effect by the main cutting motion, we reported recently that there exists another twin peak induced by secondary material swelling arising from the movement of tool tip vibration in the SPDT of titanium alloys. The additional twin peak was located at the right side of the original twin peak in FFT, displaying two twin peaks in the frequency domain of cutting force and suggesting the existence of another tool tip vibration system with a new damping factor in the SPDT of titanium alloys. Combining the effects of primary and secondary material swelling, the new dynamic model with the modified damping factor of tool tip vibration system are developed, which surface roughness of the machined titanium alloys in SPDT was predicted in higher accuracy by using the new model. The FFT of cutting force, surface roughness, and surface profile were provided in this article for the experimental validations.

The formation of serrated chips is an important feature during machining of difficult-to-cut materials, such as titanium alloy, nickel based alloy, and some steels. In this study, Ti6Al4V alloys with equiaxial and acicular martensitic microstructures were adopted to analyze the effects of material structures on the formation of serrated chips in straight line micro orthogonal machining. The martensitic alloy was obtained using highly efficient electropulsing treatment (EPT) followed by water quenching. The results showed that serrated chips could be formed on both Ti6Al4V alloys, however the chip features varied with material microstructures. The number of chip segments per unit length of the alloy with martensite was more than that of the equiaxial alloy due to poor ductility. Besides, the average cutting and thrust forces were about 8.41 and 4.53 N, respectively, for the equiaxed Ti6Al4V alloys, which were consistently lower than those with a martensitic structure. The high cutting force of martensitic alloy is because of the large yield stress required to overcome plastic deformation, and this force is also significantly affected by the orientations of the martensite. Power spectral density (PSD) analyses indicated that the characteristic frequency of cutting force variation of the equiaxed alloy ranged from 100 to 200 Hz, while it ranged from 200 to 400 Hz for workpieces with martensites, which was supposedly due to the formation of serrated chips during the machining process.