Free-standing copper (Cu) nanowire (NW) arrays have potential applications in batteries, sensors, and electrical and thermal management systems. However, the effects of geometric factors, such as the length, diameter, and growth filling ratio of Cu NWs, on their collective mechanical properties and bonding strength to substrates have not been thoroughly examined. In this study, it was found that the maximum effective modulus of the Cu NW arrays decreased from 23.8 ± 0.7 GPa to 8.6 ± 0.1 GPa as their length increased from 6.21 to 22.35 µm. Moreover, the interfacial energy per unit area between the Cu NWs and the Cu substrate was measured to be as high as 544.87 J/m2, which is significantly higher than that of other one-dimensional nanomaterial arrays. The findings from this study provide fundamental insights and references for the design, fabrication, and failure analysis of components in devices based on Cu NW arrays.

Currently, the most widely used and commercially available templates for the electrodeposition of one‐dimensional (1D) metal structures are anodic aluminum oxide (AAO) and polycarbonate track etched (PCTE) templates. Due to technical limitations in the fabrication process of these templates, their thickness is restricted to a few tens of microns (typically not exceeding 60 μm). However, some applications, such as advanced seal applications, require one‐dimensional structures that are longer, up to hundreds of microns. In this study, polydimethylsiloxane (PDMS) templates with a thickness of 200 ~ 300 μm were prepared and used for the electrodeposition of Cu microwires (MWs) for the first time. The technical processes demonstrated here can be extended to prepare other 1D metal structures with customized geometry, length, diameter, and density, paving the way for new applications of 1D metal structures. Additionally, a scratch test was conducted on the synthesized Cu MWs array to examine the bonding strength of the Cu MWs array to the Cu substrate. The results showed that the Cu MWs array has a very strong bonding strength to its underlying Cu substrate, such that no delamination of Cu MWs occurred under a normal load of 3 N during scratch testing.

Reducing contact interface thermal and electrical resistances is in great demand across various industries, particularly in the semiconductor industry. This study introduces an approach using double-sided copper nanowire (Cu NW) arrays on copper sheets as both thermal and electrical interfacial layers, designed to effectively accommodate the topographical inconsistencies between contact surfaces. Experimental outcomes reveal a significant reduction in thermal contact resistance (TCR), with a value of 2.5 mm2 K W-1, thereby exceeding the efficiency of reported nanostructural thermal interface materials (TIMs). Additionally, when utilized as an electrical interfacial layer, these double-sided Cu NWs arrays dramatically reduced electrical contact resistance (ECR), outperforming traditional conductive grease in applications necessitating separable bonding, though showing comparable performance to costly silver-based conductive epoxies required for permanent, inseparable bonds. The promising results of the double-sided Cu NWs arrays in reducing both TCR and ECR, confirmed by finite element simulation, highlight their substantial potential in advancing TIMs and electrical interconnection applications across various sectors.

Poly(p-phenylene terephthalamide) (PPTA) and ultra-high-molecular-weight polyethylene (UHMWPE) are high-performance polymer materials largely used for body armor applications. Although composite structures from a combination of PPTA and UHMWPE have been created and described in the literature, the manufacture of layered composites from PPTA fabrics and UHMWPE films with UHMWPE film as an adhesive layer has not been reported. Such a new design can provide the obvious advantage of simple manufacturing technology. In this study, for the first time, we prepared PPTA fabrics/UHMWPE films laminate panels using plasma treatment and hot-pressing and examined their ballistic performance. Ballistic testing results indicated that samples with moderate interlayer adhesion between PPTA and UHMWPE layers exhibited enhanced performance. A further increase in interlayer adhesion showed a reverse effect. This finding implies that optimization of interface adhesion is essential to achieve maximum impact energy absorption through the delamination process. In addition, it was found that the stacking sequence of the PPTA and UHMWPE layers affected ballistic performance. Samples with PPTA as the outermost layer performed better than those with UHMWPE as the outermost layer. Furthermore, microscopy of the tested laminate samples showed that PPTA fibers exhibited shear cutting failure on the entrance side and tensile failure on the exit side of the panel. UHMWPE films exhibited brittle failure and thermal damage at high compression strain rate on the entrance side and tensile fracture on the exit side. For the first time, findings from this study reported in-field bullet testing results of PPTA/UHMWPE composite panels, which can provide important insights for designing, fabricating, and failure analysis of such composite structures for body armors.

Sustainable circularity of rare earth elements (REEs) can be achieved by phytoextraction of REEs from waste and remanufacturing them as value-added products. We have demonstrated erbium, europium, gadolinium, neo-dymium, and yttrium uptake using Eleocharis acicularis. The highest accumulation was observed for neodymium and gadolinium (56 and 55 mg/g dry weight), whereas yttrium (39 mg/g dw) had the lowest bioaccumulation from a feed solution of 300 mg/L over 10 days. The REE-accumulated biomass was used as raw material for graphitization at 1200 degrees C. A higher degree of graphitization was observed in REE-graphitic material (GM) (0.91-0.97) and the lowest was observed in the non-exposed control biomass-GM (0.81), indicating the catalytic action of the REEs. XRD and SAED diffractograms showed the multilayer polycrystalline nature of the GMs, and Raman spectra demonstrated the presence of sp2 hybridization. Furthermore, Gd-GM had higher conductivity (1.09 x 104 S/m) than the commercial graphite (8.21 x 103 S/m) at 30 MPa applied pressure. The REE-GMs showed high capacitance (measured at 20-300 kHz) and an optical band gap of less than 1.11 eV. Addition-ally, Gd-GM showed significant paramagnetic properties, making it a potential precursor for sustainable MRI contrast agent synthesis.

Due to its desirable mechanical properties, compacted graphite iron (CGI) has been used to replace conventional gray cast iron (CI) in various applications, such as automotive engine blocks and cylinder heads. However, the poor machinability of CGI can lead to excessive tool wear and consequently high manufacturing costs. Various strategies have been developed to improve the machinability of CGI, including optimizing machining parameters and the development of novel metalworking fluids. In this study, machining of CGI was conducted using cubic boron nitride (cBN) tools under different cutting speeds, with both soluble and full-synthetic water-based metalworking fluids at different levels of sulfur addition and water dilution. The effects of the metalworking fluids on the tool wear behavior were examined. Results showed that at 200 m/min cutting speed, the soluble metalworking fluid at 4% dilution and 0.3% sulfur compound exhibited the best performance, with a cutting distance reaching 23.8 km. In contrast, the least effective soluble metalworking fluid at 9% dilution and 0.3% sulfur compound resulted in a 28.6% decrease in the cutting distance (17.0 km) compared to the best one. At a higher speed (300 m/min), the cutting distance for all metalworking fluids dropped to less than 6.0 km, with the full-synthetic metalworking fluid showing the shortest cutting distance of 4.8 km.

Poly(p-phenylene terephthalamide) (PPTA) is a high-performance polymer that has been utilized in a range of applications. Although PPTA fibers are widely used in various composite materials, laminar structures consisting of PPTA and ultra-high-molecular-weight polyethylene (UHMWPE), are less reported. The difficulty in making such composite structures is in part due to the weakness of the interface formed between these two polymers. In this study, a layered structure was produced from PPTA fabrics and UHMWPE films via hot pressing. To improve the interlayer adhesion, oxygen plasma was used to treat the PPTA and the UHMWPE surfaces prior to lamination. It has been found that while plasma treatment on the UHMWPE surface brought about a moderate increase in interlayer adhesion (up to 14%), significant enhancement was achieved on the samples fabricated with plasma treated PPTA (up to 91%). It has been assumed that both surface roughening and the introduction of functional groups contributed to this improvement.

This research aims to study the effect of a composite coating comprised of polydopamine (PDA), polytetrafluoroethylene (PTFE), and activated Carbon on the insertion mechanics of surgical needles in tissues i.e., polyvinyl chloride (PVC) tissue phantom and bovine kidney. A needle insertion and extraction test system was designed and constructed to measure the insertion and extraction forces. It was found that the composite coating on the needle surface decreases the maximum average insertion and extraction forces by 62% and 64%, respectively, when tested in PVC tissue phantom and by 49% and 30%, respectively, in bovine kidney tissue. Additionally, an Atomic Force Microscope study was performed to characterize the surface properties of the coated needles. It was found that the composite coating reduced the friction force on the needle surface by 65.7%. The decrease in these forces is critical in minimizing tissue damage and decreasing needle path deviation or deflection during percutaneous procedures.

The significant size distribution of as-synthesized nanomaterials presents a challenge for reproducable and reliable applications. In this paper, we report a fluidic-assisted sorted assembly method in which nanomaterial sorting and enhanced assembly can be achieved simultaneously. As a proof of concept, a two-dimensional (2D) graphene flake, with a large size variation, was chosen as the target nanomaterial system. This study synergizes a novel fluidic assembly design, suspending a rotating disk over a polydimethylsiloxane (PDMS) substrate, and a computational fluid dynamics (CFD) model using Ansys CFX to disclose the mechanism of sorted assembly. By controlling the rotating speed and the gap between the disk and the substrate, the flow field is altered. In contrast to centrifugal sorting, where larger particles move outward, in this study, the size of assembled graphene flake (average lateral size, Xc) reduces significantly from the center (Xc = 3 μm) to the edge of the disk (Xc = 2 μm). The particle sorting process is dictated by the fluid shear-stress, with higher shear-stress leading to smaller particles, while the assembly process is mainly dominated by the pressure field with higher pressure magnitude leading to better assembly. Near the edge of the disk, enhanced particle sorting is coupled with an enhanced assembly where a continuous graphene film with smaller Xc can be formed. To prove the potential application of this method, an ultrasensitive strain sensor with one of the lowest detection limits, 0.02%, is demonstrated. This research presents a novel route toward large-scale and cost-effective manufacturing of nanomaterial-based flexible electronics.

This study is aimed to evaluate the effects of coated surgical needles with composite polymers such as polydopamine (PDA), polytetrafluoroethylene (PTFE), and carbon. The coated needle’s lubrication properties were measured using 3 DOF force sensors and 3D robot system by the repetitive insertion in soft tissue materials. Needle durability is a measure of needle sharpness after repeated passage through high stiffness tissue materials. The composite coatings were shown to reduce the insertion force by ∼49% and retraction forces by ∼46% when tested using a bovine kidney. The surface roughness and the lateral friction force of the needle are measured using the Atomic Force Microscope (AFM). The adhesion energy of the different coating on the needle will be measured using a nano-scratch method.

The challenges in achieving a green and scalable integration of two-dimensional (2D) materials with flexible polymer substrates present a major barrier for the application of 2D materials, such as graphene, MoS2, and h-BN for flexible devices. Here, we create a sono-assisted surface energy driven assembly (SASEDA) method that can achieve foot-scale to micrometer-scale assembly of 2D materials, form a conductive network in as short as 10 s, and build hierarchical and hybrid flexible devices such as sensors, resistors, and capacitors by using water as the dispersion solvent. SASEDA highlights two counterintuitive innovations. First, we use an "unfavorable" solvent (i.e., water) for both 2D materials (e.g., graphene, MoS2, and h-BN) and polymer substrates (e.g., polydimethylsiloxane) to drive the assembly process. Second, we use a weak sono-field (0.3 W/cm2) generated by a regular sonication bath cleaner to enhance the assembly efficiency and reorganize and unify the assembly network. This method and its principle pave the way toward affordable large-scale 2D material-based flexible devices.

A new method to directly grow graphene on quartz glass substrate by atmospheric-pressure chemical vapor deposition (CVD) without using any catalyst was developed. The prime feature of this method is to build a vertical-glass model in the quartz tube to significantly increase the collision probability of the carbon precursors and reactive fragments between each other with the glass surface. The growth rate of high-quality graphene on glass remarkably increases compared with the conventional gas flow CVD technique. The optical transmittance and sheet resistance of the graphene glass can be readily adjusted by regulating growth time. When growth time is 35 min, the graphene glass presents an intriguing sheet resistance of about 1.48 k Omega sq(-1) at a transmittance of 93.08% and exhibits an excellent hydrophobic performance. The method is simple and scalable, and might stimulate various potential applications of transparent and conductive graphene glass in practical fields. (C) 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

A novel hybrid of Cu nanoparticles/three-dimensional graphene/Ni foam (Cu NPs/3DGr/NiF) was prepared by chemical vapor deposition, followed by a galvanic displacement reaction in Ni- and Cu-ion-containing salt solution through a one-step reaction. The as-prepared Cu NPs/3DGr/NiF hybrid is uniform, stable, recyclable and exhibits an extraordinarily high catalytic efficiency for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a reduction rate constant K = 0.056 15 s-1, required time ∼30 s and excellent sensing properties for the non-enzymatic amperometric hydrogen peroxide (H2O2) with a linear range ∼50 μM-9.65 mM, response time ∼3 s, detection limit ∼1 μM. The results indicate that the as-prepared Cu NPs/3DGr/NiF hybrid can be used to replace expensive noble metals in catalysis and sensing applications.

The application of Au nanoparticles (Au NPs) often requires surface modification with chemical surfactants, which dramatically reduce the surface activity and increase the chemical contamination and cost of Au NPs. In this research, we have developed a novel Au NPs/reduced graphene oxide/Ni foam hybrid (Au NPs/RGO/NiF) by in situ reduction through ascorbic acid and replacement reaction. This method is green, facile and efficient. The Au NPs are free of chemical surfactants and are homogeneously distributed on the surface of the RGO/NiF. The as-prepared Au NPs/RGO/NiF hybrid is uniform, stable and exhibits not only a high reduction efficiency for the reduction of 4-nitrophenol with a catalytic kinetic constant of up to 0.46 min-1 (0.15 cm3 catalysis) but also a sensitive and selective detection of H2O2 with a detection limit of ∼1.60 μM.

The excellent catalytic properties of silver (Ag) nanoparticles (AgNPs) are generally deteriorated during use because of their irreversible agglomeration and the surfactants coating them. In this research, a novel hybrid structure of as-synthesized silver nanoparticles/zinc oxide nanosheets/graphene/nickel foam (AgNPs/ZnO/Gr/NiF) was prepared using chemical vapor deposition (CVD) combined with a hydrothermal reaction and in situ reduction with ascorbic acid. The as-prepared AgNPs/ZnO/Gr/NiF hybrid structure was characterized using Raman spectrometry,scanning electron microscopy, and X-ray diffraction. The ZnO nanosheets were identified as an effective buffer layer to improve the homogeneity and stability of the as-synthesized AgNPs on the surface of Gr/NiF hybrid structure because of its assisted role in carrying and immobilizing the AgNPs to the surface of Gr/NiF via chelation and complexation of arginine to both ZnO and Ag ions during the in situ reduction process of Ag ions. The as-prepared AgNPs/ZnO/Gr/NiF hybrid structure is flexible and exhibits high efficiency and recyclability for the reduction of 4-nitrophenol to 4-aminophenol.