We present a fast method to prepare hybrid materials of polyaniline (PAni) with carbon nanotubes (CNTs, both undoped and nitrogen-doped) by ball milling without solvents or strong oxidants. PAni forms nanoparticles, attached to CNTs in a nanocomposite structure, with the nanotubes well dispersed among the polymer. This is achieved with only a few minutes of ball milling. Raman spectroscopy confirms that PAni was synthesized in its conductive state and suggests a good CNT–PAni interaction, particularly with nitrogen-doped CNTs. We found that water increased polymer yield, which we optimized, together with the nanocomposite conductivity, as function of amount of water and of oxidant (FeCl3). The nanocomposite conductivity is four orders of magnitude higher than that of PAni, for both types of nanotubes. Scanning electron microscopy and X-ray diffraction both show negligible damage to the CNT during this mechanosynthesis procedure, while dry milling and milling CNT in water without aniline does damage nanotubes, indicating that the reaction absorbs most of the mechanical energy.

Nanoindentation experiments performed in 5 and 18 μm thick vapor deposited polycrystalline lithium films at 31 °C reveal the mean pressure lithium can support is strongly dependent on length scale and strain rate. At the smallest length scales (indentation depths of 40 nm), the mean pressure lithium can support increases from ∼23 to 175 MPa as the indentation strain rate increases from 0.195 to 1.364 s−1. Furthermore, these pressures are ∼46–350 times higher than the nominal yield strength of bulk polycrystalline lithium. The length scale and strain rate dependent hardness is rationalized using slightly modified forms of the Nabarro–Herring and Harper–Dorn creep mechanisms. Load–displacement curves suggest a stress and length-scale dependent transition from diffusion to dislocation-mediated flow. Collectively, these experimental observations shed significant new light on the mechanical behavior of lithium at the length scale of defects existing at the lithium/solid electrolyte interface.

Mastery of strengthening strategies to achieve high-capacity anodes for lithium-ion batteries can shed light on understanding the nature of diffusion-induced stress and offer an approach to use submicro-sized materials with an ultrahigh capacity for large-scale batteries. Here, we report solute strengthening in a series of silicon (Si)–germanium (Ge) alloys. When the larger solute atom (Ge) is added to the solvent atoms (Si), a compressive stress is generated in the vicinity of Ge atoms. This local stress field interacts with resident dislocations and subsequently impedes their motion to increase the yield stress in the alloys. The addition of Ge into Si substantially improves the capacity retention, particularly in Si0.50Ge0.50, aligning with literature reports that the Si/Ge alloy showed a maximum yield stress in Si0.50Ge0.50. In situ X-ray diffraction studies on the Si0.50Ge0.50 electrode show that the phase change undergoes three subsequent steps during the lithiation process: removal of surface oxide layer, formation of cluster-size Lix(Si,Ge), and formation of crystalline Li15(Si,Ge)4. Furthermore, the lithiation process starts from higher index facets, i.e., (220) and (311), then through the low index facet (111), suggesting the orientation-dependence of the lithiation process in the Si0.50Ge0.50 electrode.

Nanoindentation experiments performed in high-purity vapor deposited lithium films at 31 °C reveal a strain rate and length scale dependence in the stress at which pop-in type events signal an abrupt transition from diffusion to dislocation-mediated flow. The stress level at which the transition to dislocation-mediated flow occurs varies with the strain rate and ranges from 88 to 208 times larger than the nominal yield strength of bulk, polycrystalline lithium. Variation in the indentation strain rate reveals the relationship between the stress required to initiate the transition and the length scale at which the transition occurs follows the power-law relation, hardness × depth1.17 = 1.545 N/m0.83, where the magnitude of the exponent and constant reflect the defect structure of the film. A rationalization of the transition is provided through direct comparisons between the measured cumulative distribution function (CDF) and the CDF hypothesized for the activation of a Frank–Read source.

A novel luminogen-functionalized SBA-15, denoted as SNT, was developed by incorporating tris(4-bromophenyl)amine (TBPA) into SBA-15 via a “fixation-induced emission” strategy. The emission of TBPA on the matrix of SBA-15 was greatly enhanced, making the SNT possible as a fluorescence sensor. Cefalexin, a typical antibiotic, was chosen as the model analyte to be assayed and sensitive detection performance was achieved. This is the first time for cefalexin to be detected by a fluorescent method. Moreover, the SNT can be recycled by simply washing with proper solvents then used for next detection. This work provides a strategy to greatly improve the emission characteristics of fluorophores, even if a mediocre small fluorophore. It can be extended to design practical fluorescent sensors with high performance and recyclability by this strategy.

Nanoindentation has been used to measure the elastic modulus of 5 and 18 μm thick high-purity vapor deposited polycrystalline lithium films at 31 °C. Over indentation depths ranging from 150 to 1100 nm, the modulus is found to vary with film thickness from 9.8 GPa ± 11.9% to 8.2 GPa ± 14.5%. These results are well within the range of lithium's orientation dependent elastic modulus, which spans approximately 3.1 to 21.4 GPa. The measured values may also indicate (111) and (100) texture for the 5 and 18 μm thick films, respectively. The potential effects of pileup and surface contamination are found to be negligible if any at all. Small but discernible changes in damping capability near the free surface may provide insight into the subsurface defect structure and the potential for localized heating. Numerous experimental challenges are addressed and key metrics are used to validate the measured elastic modulus.

A numerical nanoindentation model was developed using the Material Point Method (MPM), which was chosen because it can handle both large deformations and dynamic contact under the indenter. Because of the importance of contact, prior MPM contact methods were enhanced to improve their accuracy for contact detection. Axisymmetric and full 3D simulations investigated the effects of hardening, strain-rate dependent yield properties, and local structure under the indenter. Convergence of load–displacement curves required small cells under the indenter. To reduce computation time, we used an effective nonregular grid, called a tartan grid and describe its implementation. Tartan grids reduced simulation times by an order of magnitude. A series of simulated load–displacement curves were analyzed as “virtual experiments” by standard Oliver–Pharr methods to extract effective modulus and hardness of the indented material. We found that standard analysis methods give results that are affected by hardening parameters and strain-rate dependence of plasticity. Because these parameters are not known during experiments, extracted properties will always have limited accuracy. We describe an approach for extracting more properties and more accurate properties by combining MPM simulations with inverse methods to fit simulation results to entire load–displacement curves.

Single-crystal-like TiO2 is claimed to be a very promising material among various catalysts. In this study, the (N,F)-co-doped single-crystal-like TiO2 was prepared by a new molten mixing process in which the mixed nitrates were used both as a morphology modifier and an N-doping agent at the same time. The prepared samples also had well-developed (001) facet due to the addition of HF. The HF can also be an F doping agent to the material. The co-doping of N and F can diminish the band gap of TiO2 from 3.05 to 2.93 eV, therefore visible light can be used effectively by the material. In addition, NO and fluorine ions existing on the surface of the sample can also help its photocatalyticity. Therefore, the photocatalytic performance of the as-prepared sample was effectively improved.

Induced pluripotent stem cells (iPSCs) offer the possibility to accelerate tissue reconstruction through cell differentiation. The use of iPSCs in bone tissue engineering is promoted by next generation scaffolds which guide bone tissue repair and provide specific cues and molecular recognition to enhance differentiation as well as the bone forming ability of these cells. However, bone tissue repair faces additional challenges such as requirement for a consequent bone vasculature and exhaustion of stem cells in the aging adults. In this context, iPSC reprogramming seems to be unaffected by age and they have better pro-angiogenic potential as well as proliferation rate. The benefits of iPSCs using polymeric scaffolds include access to humanized in vitro models, triggering bone tissue reconstruction through a supply of bone cells via differentiation, compensating mesenchymal stem cells age-related deficiencies in osteodegenerative diseases, and enhancing angiogenesis.

ZnO-based oxides are promising for thermoelectric energy generation at elevated temperatures. We study electrical transport properties of Ni-doped ZnO applying the density functional theory, indicating increase of the electrical conductivity (σ) and decrease of the Seebeck coefficient (S) due to Ni-doping, in full accordance with experimental results. We calculate the temperature-dependent σ and S applying the Boltzmann transport theory, approximating the electron relaxation time, τe. Good agreement with experimental data is obtained considering both temperature and energy dependence of τe. This yields explicit expressions for τe and provides us with powerful predictive tool assessing electronic transport in ZnO.

The effect of equal-channel angular pressing (ECAP) at various temperatures (310, 330, and 350 °C) on precipitations and strengthening mechanisms of Mg–9Al–1Si alloys was investigated. The results indicated that the average grain size decreased gradually with decreasing of ECAP temperature. The distribution of the Mg2Si phase changed a little when the ECAP temperature increased. However, the different morphologies of β-Mg17Al12 phase were observed, including continuous and uncontinuous precipitation of particles at 310 and 350 °C. The continuous β-Mg17Al12 phase was hardly found and the refined β-Mg17Al12 phase was distributed dispersedly in the matrix at 330 °C. Thus, the mechanical properties of the Mg–9Al–1Si alloy was optimum: ultimate tensile strength and elongation were ∼350.8 MPa and ∼14.77%, respectively. It can be deduced that both grain refinement strengthening and precipitation strengthening play significant roles in strength increment of the alloy during the ECAP process. However, precipitation strengthening is the predominant mechanism.

The soft magnetic alloy Fe–Co–2V, also known as Permendur-2V or Hiperco® 50A, was subjected to equal channel angular extrusion (ECAE) at 750–850 °C using two processing routes. Hiperco is a trade name of Carpenter Technology Corporation. ECAE, which is a severe plastic deformation process, refined the grain size to about 1.5–3 μm, compared to 25–70 μm for the conventional Hiperco® bar. The fine-grain microstructure is homogenous throughout the ECAE material, from center to edge, due to the simple-shear ECAE process. Fine-grained Hiperco® has previously only been obtainable in the sheet form. ECAE resulted in yield and tensile strengths of 650–700 MPa and 900–1400 MPa, respectively, representing a 2–3-fold strength increase compared to the conventional bar. The yield strength was demonstrated to fit well to the Hall–Petch relationship established using previous reports on the strength of conventional bar and sheet materials. High ductility, up to 18%, was obtained in the ECAE processed billets and attributed primarily to the partially disordered bcc crystal structure upon quenching from ECAE.

Laser-assisted material extrusion was used in this study to realize high-performance 3D printing of semicrystalline polymers. A CO2 laser device was simply integrated into a traditional fused deposition modeling printer to supply the laser. The sample’s surface temperature was changed by controlling the laser power during printing, and thus the interlayer shear strength and crystallinity could both be effectively controlled. By implementing the laser-assisted process, the optimal interlayer shear strength of poly(ether ether ketone) (PEEK) could be improved by more than 45%, and the degree of crystallinity of PEEK was simultaneously improved by up to 34.5%, which has approached to the typical crystallinity of 35%. Therefore, the process provides a very effective solution for additive manufacturing of semicrystalline materials and helps clearly to establish a controllable mapping relationship between the laser parameters and material properties.

To increase the corrosion prevention of stainless steel implant and fast recovery due to new bone-cell formation at the orthopedic implant site, in the present investigation, a trilayered (with bioceramic interlayer sandwiched between innermost passivated surface and outermost polymer coating) 316L stainless steel (SS) implant was designed and investigated. It was inferred that this new designed implant invokes faster and more bone-cell formation than uncoated commercially available 316L SS implants. Faster bone-cell formation at the coated implant site reduces the initial threat of implant corrosion. The electrochemical corrosion study proved that this model of coated implants is able to prevent corrosion up to 90% better than uncoated commercially available 316L SS. Subsequently, preclinical studies in the rabbit bone defect model (which included histology, radiology, fluorochrome labeling, push-out test, and scanning electron microscopy taken after 45 and 90 days) proved higher rate of new bone tissue formation and better push-out strength between tissue in contact and the coated implant. The toxicological study of vital organs like liver, kidney, and heart also exhibited no abnormality. The outcome of the experimentations indicates suitability of this trilayered 316L SS implant for bone repair and healing.

Herein we describe the use of a new DNAzyme/graphene hybrid material as a biointerfaced sensing platform for optical detection of pathogenic bacteria. The hybrid consists of a colloidal graphene nanomaterial and an Escherichia coli-activated RNA-cleaving DNAzyme and is prepared via non-covalent self-assembly of the DNAzyme onto the graphene surface. Exposure of the hybrid material to E. coli-containing samples results in the release of the DNAzyme, followed by the cleavage-mediated production of a fluorescent signal. Given that specific RNA-cleaving DNAzymes can be created for diverse bacterial pathogens, direct interfacing of graphene materials with such DNAzymes represents a general and attractive approach for real-time, sensitive, and highly selective detection of pathogenic bacteria.

A novel, alloy-agnostic, nanofunctionalization process has been utilized to produce metal matrix composites (MMCs) via additive manufacturing, providing new geometric freedom for MMC design. MMCs were produced with the addition of tungsten carbide nanoparticles to commercially available AlSi10Mg alloy powder. Tungsten carbide was chosen due to the potential for coherent crystallographic phases that were identified utilizing a lattice-matching approach to promote wetting and increase dislocation interactions. Structures were produced with evenly distributed strengthening phases leading to tensile strengths >385 MPa and a 50% decrease in wear rate over the commercially available AlSi10Mg alloy at only 1 vol% loading of tungsten carbide.