Coatings with low friction coefficient and excellent anti-wear and anticorrosion performances are of great interest for fundamental research and practical applications. In the present study, Cobalt–nickel–phosphorus/graphene oxide (Co–Ni–P/GO) composite coating is prepared by a pulse electrodeposition method. Effect of the embedded GO sheets on the microstructures, microhardness, and electrochemical and tribological behaviors of the Co–Ni–P/GO composite coating are researched in detail. The results reveal that the co-deposition of GO sheets significantly improves the microhardness of the as-prepared Co–Ni–P/GO composite coating and changes the morphology of the Co–Ni–P coating from hemispheric structure to nodule structure with smaller globular particles for the Co–Ni–P/GO composite coating. In addition, friction and wear tests show that the incorporation of GO sheets endows the Co–Ni–P/GO composite coating with remarkable friction reduction and improved wear resistance. Electrochemical corrosion tests demonstrate that the Co–Ni–P/GO composite coating possesses better corrosion resistance than the Co–Ni–P coating.

In the present study, TiO2NT coatings grown on simulated body fluid-based electrolyte were investigated as drug delivery devices. Nanotubes (NTs) were grown over commercially pure Ti and Ti6Al4V alloy. Morphology analysis showed that NTs in alloy samples present an inner diameter of 10 nm smaller in average than NTs grown over pure Ti. The surface wettability in water decreased with the anodizing time for both substrates. The application of coatings as drug delivery devices has been studied through the incorporation of ciprofloxacin. To control the drug release, collagen was used as the diffusional barrier. It was observed the drug release follows a Fick’s kinetics. Bioactivity assays showed the absence of hemolytic activity. The concentration of the drug during the release interval remained below the toxic concentration limit, presenting a bacteriostatic activity. All coatings prepared presented a high antibacterial activity, being the area of inhibition of bacterial growth above 13 times the area of the implant.

Ceramic–metal composites are an important group of materials that have gained interest recently because of their peculiar properties. There have been numerous studies on the reinforcement of alumina through the incorporation of various ductile metals in it. However, these studies have been limited to determining the effect of the addition of metals on the mechanical properties of ceramics, without determining the effect of these metal additions on other physical properties of the resulting composite. In this way, in agreement with the obtained results, we have that because of the conductive nature of metals, there is a considerable decrease in the electrical resistivity of alumina, mainly when copper is added to it. However, in terms of optical performance, alumina matrix composites showed significant changes in absorbance in the visible spectra. The addition of iron, titanium, and yttrium enhanced the absorbance of alumina, whereas manganese addition significantly decreased the optical absorption.

The cyclic oxidation experiment of yttria-stabilized zirconia coatings deposited on NiCoCrAlYHf alloys by air plasma spraying was investigated at 1050 °C in air and in air containing water vapor. The results revealed that water vapor has a great influence on the oxidation resistance of the thermal barrier coatings (TBCs). Compared with the samples oxidized in air atmosphere, TBCs oxidized in air containing water vapor had a longer lifetime. It was also found that different atmospheres could lead to different HfO2 formation positions, which could decrease the rumpling in the oxide layer. In particular, after the coatings on Hf-doped NiCoCrAlY were first pretreated in air containing water vapor for 24 h at 1050 °C, the lifetime of the pretreated coating was doubled compared to the coating in laboratory air only. The water vapor pretreatment of the coatings could be an important method for optimizing the lifetime of TBCs.

Elastic modulus and residual stress in freestanding ultrathin films (<100 nm) are characterized using bilayer cantilevers. The cantilevers comprise a test film and a well-characterized reference material (SU-8). When released from the substrate, residual stresses in the bilayer cantilever cause it to deflect with measurable curvatures, allowing the determination of both stiffness and residual stress of the test film. The technique does not require sophisticated mechanical test equipment and serves as a useful metrology tool for characterizing coatings immediately after fabrication in a clean room assembly line. The measured biaxial modulus and residual strain of 75 nm copper films are 211 ± 19 GPa and (7.05 ± 0.22) × 10−3, respectively. Additional experiments on the freestanding structures yield a mean Young’s modulus of 115 GPa. These properties are in close agreement with those measured from additional residual stress–driven structures developed on the same coatings by the authors.

Measuring the elastic and plastic properties with nanoindentation is predicated on the indentation not fracturing the material. In this study, an unloading curve analysis is used to identify indentation-induced fracture in brittle molecular organic crystals to define conditions, where properties measurements are accurate, and for calculating the toughness. Single crystals of cyclotetramethylene tetranitramine (HMX) and idoxuridine were indented from 1 to 300 mN with indenter probes of varying acuity to identify fracture initiation loads. Idoxuridine displayed no fracture up to and at 100 mN, with fracture occurrence then seen at an increasing rate until every indentation made induced fracture at 300 mN. HMX displayed no fracture up to and at 4 mN, with fracture then occurring at an increasing rate until every sample fractured at 8 mN. The toughness of HMX and idoxuridine is ≈0.28 ≈ 0.4–0.5 MPa/m1/2, respectively.

The antibacterial hydrogels can be widely used in the biomedical area owing to their excellent properties. The main limitation of antibacterial hydrogels is their poor mechanical strength. In this study, the novel hydrogels were fabricated with a mixture of silk fibroin (SF), chitosan (CH), agarose (AG), and silver nanoparticles (SNPs) via facile reaction condition without inorganic substances. The mechanical property of these fabricated hydrogels can be modulated by the concentration of SF or AG. The rheological studies demonstrated enhanced elasticity of CH-doped hydrogels. Because of the presence of CH and Ag in hydrogels, the antimicrobial property against gram-positive and gram-negative bacteria was exhibited. Cytocompatibility test proved the very low toxic nature of the hydrogels. In addition, these composite hydrogels have a smaller porosity, higher swelling ratio, and good compatibility, indicating their great potential for biomedical application.

In our previous study, we observed a lack of $\left\{ {10\bar{1}2} \right\}$ twinning in a deformed Mg–Y alloy, which contributed to the observed yield “symmetry.” However, the effects of texture and grain size on polycrystalline deformation made it difficult to fully understand why twinning was not active. Therefore, we report herein in-depth study by in situ transmission electron microscopy, i.e., in situ TEM. The in situ deformation of nano-sized Mg–Y pillars revealed that prismatic slip was favored over twinning, namely, the critical stress required to activate prismatic slip was lower than that for twinning. This finding diametrically differs from that reported in other nano/micro-pillar deformation studies, where twinning is always the dominant deformation mechanism. By measuring the critical stresses for basal, prismatic, and pyramidal slip systems, this in situ TEM study also sheds light on the effects of the alloying element Y on reducing the intrinsic plastic anisotropy in the Mg matrix.

Macro-mesoporous zirconium titanate monoliths have been successfully prepared via a sol–gel process accompanied by phase separation, with poly(ethylene oxide) (PEO) as a phase separation inducer and N-methylformamide (NFA) as a gelation accelerator. The size and morphology of macropores are controlled by the PEO and NFA amount. By choosing appropriate starting composition, the co-continuous structure could be obtained. The as-dried gel is amorphous, the pore size is in the range of 0.05–0.5 μm, the porosity is 46%, and the surface area is 111 m2/g. After heat treatment at 500 °C, the gel transforms into the phase ZrTiO4, the macropore diameter decreases slightly, the porosity increases to 63%, and the surface area decreases to 40 m2/g. Moreover, the macroporous structure is well maintained, and the skeleton becomes dense and smooth. The samples have macropores, mesopores, and micropores before and after heat treatment.

The flow softening behavior caused by deformation heating of the 6063 aluminum alloy was investigated employing uniaxial compression tests. The adiabatic correction factor (η) and mechanical work partitioning factor (φ), commonly considered to be constant, were found to be highly variable at medium strain rates, namely from 0.01 to 10 s−1. η decreased with increasing strain and decreasing strain rate, but it was relatively not sensitive to temperature. φ, traditionally taken to be a constant of 0–10%, was found to vary from 2.8% at a temperature of 623 K and a strain rate of 10 s−1 to 26.8% at a temperature of 773 K with a strain rate of 0.01 s−1. An expression for temperature rise involving these two variable factors was optimized. FEM simulation using the corrected and uncorrected true stress–strain curves and corresponding extrusion experiment were carried out. Comparisons between the simulated and experimental results confirmed the temperature compensation was trustable.

Hot extrusion experiments were conducted on Al–5.50Zn–2.35Mg–1.36Cu (wt%) alloy under various temperatures and extrusion speeds. Results indicated that dynamic recovery occurred at low temperature and then dynamic recrystallization was triggered at higher temperature or speed. High billet temperature reduced the grain size and increased the volume fraction of Al23CuFe4 and AlMgZn. When the extrusion speed was enhanced to 0.5 mm/s, the peak of MgZn2 phase diminished in the results of X-ray diffraction. The strong brass and S components appeared in all the extruded specimens. Texture intensity gradually decreased with increasing temperature and the fraction of texture components was also significantly affected by the extrusion parameters. The extruded alloy exhibited the highest ultimate tensile strength of 350.2 MPa at 480 °C and 0.5 mm/s and the best elongation of 16.78% at 520 °C and 0.1 mm/s. Moreover, the extrusion speed had more significant effects on the tensile properties than that of the temperature.

Reactions in Ni/Al nanolaminates exhibit high combustion temperatures and wave speeds that are customizable through changes to nanostructure. Nanolaminates fabricated via vapor deposition exhibit columnar grains with average diameters on the order of the individual layer thickness; yet, their role on nanolaminate combustion has not been previously investigated. The current work uses molecular dynamics simulations to elucidate the effect of grain size on reaction rates and combustion temperatures in Ni/Al nanolaminates. Decreasing grain size is shown to increase reaction rates as well as increase peak temperatures consistent with the excess enthalpy of smaller grain sizes. Additionally, grain boundaries provide heterogenous nucleation sites for the diffusion-restricting B2–NiAl phase. Focusing on Ni diffusion into liquid Al, an effective diffusion coefficient is computed as a function of grain size, which may be used in thermodynamic models for this stage of the reaction.

Two wide band gap conjugated polymers, namely PBDT-TT25 and PBDT-TT36, derived from (4,8-bis(4,5-dioctyl-thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane) with 2,5-dibromothieno[3,2-b]thiophene (TT25) or 3,6-dibromothieno[3,2-b]thiophene (TT36), have been synthesized by simply altering the linker positions of thieno[3,2-b]thiophene unit. The impact of linker positions on the energy levels, aggregation, active layer morphology, and optical and photovoltaic properties was evaluated systemically. We found that the absorption was greatly broadened, and the highest occupied molecular orbital (HOMO) energy level was elevated as the result of the significantly reduced twist angle on the polymer backbone when the linker positions changed from 3,6-isomer to 2,5-isomer. Therefore, the optimal inverted polymer solar cells exhibited a 1.87 times enhancement in power conversion efficiencies (PCE), which was mainly ascribed to the higher short circuit current densities (JSC) and fill factor (FF) of the devices mainly benefited from the widened, stronger absorption, higher hole mobility, and more ordered structure.

Perovskite chalcogenides are gaining substantial interest as an emerging class of semiconductors for optoelectronic applications. High-quality samples are of vital importance to examine their inherent physical properties. We report the successful crystal growth of the model system, BaZrS3 and its Ruddlesden–Popper phase Ba3Zr2S7 by a flux method. X-ray diffraction analyses showed the space group of Pnma with lattice constants of a = 7.056(3) Å, b = 9.962(4) Å, and c = 6.996(3) Å for BaZrS3 and P42/mnm with a = 7.071(2) Å, b = 7.071(2) Å, and c = 25.418(5) Å for Ba3Zr2S7. Rocking curves with full width at half maximum of 0.011° for BaZrS3 and 0.027° for Ba3Zr2S7 were observed. Pole figure analysis, scanning transmission electron microscopy images, and electron diffraction patterns also establish the high quality of the grown crystals. The octahedral tilting in the corner-sharing octahedral network is analyzed by extracting the torsion angles.

More than 1 million tons of oil is inadvertently spilled each year. The economic and environmental costs of these spills are enormous and compel further development of environmentally friendly sorbent materials. Here, we demonstrate a vapor-phase modification approach to create a new class of oil sorbents composed of cellulosic materials (cotton) coated with a subnanometer layer of inorganic oxide. This new cellulosic sorbent remains buoyant in water indefinitely and achieves a selective oil sorption capacity (23 g/g or 1.05 g/cm3) that is at least 35 times better than untreated cellulose in aqueous environments. This new sorbent particularly excels under “realistic” conditions such as continuous agitation (e.g., simulated waves) and presoaking in water (e.g., rain or forced immersion). When sorption performance is compared on a per-volume basis—which better captures use conditions than a per-mass basis—this modified natural product becomes comparable to the best sorbents reported in the literature.

An analysis of indentation cyclic behavior of polymers is carried out with the aim to tackle time-dependent behavior of polymer at several time scales by one test. The method consists in cycling the load between a positive close-to-zero value and a maximum peak value (10 mN in this study) for long time with constant loading rate. The short time scale is characterized through the instantaneous elastic modulus determined from reloading curves at each cycle. The advantages of determination of instantaneous elastic modulus from reloading instead of commonly used unloading curves are discussed. The energy dissipation describes viscoelasticity and plasticity at the time scale of one cycle. The evolution of both parameters with cycles along with the cyclic creep describes the long-time viscoelasticity. The cyclic indentation behavior of poly(methyl methacrylate), PR520 epoxy, and high-density polyethylene (HDPE) polymers is analyzed, and a comparison with the macroscopic cyclic behavior of HDPE is presented.

A novel series of nanocrystalline AlCuCrFeMnWx (x = 0, 0.05, 0.1, 0.5) high-entropy alloys (HEAs) were synthesized by mechanical alloying followed by spark plasma sintering. The phase evolution of the current HEAs was studied using X-ray diffraction (XRD), transmission electron microscopy, and selected area electron diffraction. The XRD of the AlCuCrFeMn sintered HEA shows evolution of ordered B2 phase (AlFe type), sigma phase (Cr rich), and FeMn phase. AlCuCrFeMnWx (x = 0.05, 0.1, 0.5 mol) shows formation of ordered B2 phases, sigma phases, FeMn phases, and BCC phases. Micro-hardness of the AlCuCrFeMnWx samples was measured by Vickers microindentation and the maximum value observed is 780 ± 12 HV. As the tungsten content increases, the fracture strength under compression increases from 1010 to 1510 MPa. Thermodynamic parameters of present alloys confirm the crystalline phase formation, and finally structure–property relationship was proposed by conventional strengthening mechanisms.

When a metal oxide surface is immersed in aqueous solution, it has the ability to bind, orient, and order interfacial water, affecting both chemical and physical interactions with the surface. Structured interfacial water thus possesses time-averaged, spatially varying polarization charge and potential that are comparable to those arising due to ion accumulation. It is well established that interfacial water structure propagates from the surface into bulk solution. Here, we show that interfacial water structure also propagates laterally, with important consequences. The constant pH molecular dynamics was used to impose a pH difference between opposite faces of a model goethite (α-FeOOH) nanoparticle and quantify water polarization charge on intervening faces. We find that the structure of water on one face is strongly affected by the structure on nearby surfaces, revealing the importance of long-range lateral hydrogen bonding networks with implications for particle aggregation, oriented attachment, and processes such as dissolution and growth.

Environmental pollution and energy shortages seriously restrict the development of society. Photocatalytic oxidation technology can directly use solar energy to drive a series of chemical reactions. It has the advantages of low energy consumption, mild reaction conditions, and no secondary pollution, and is an effective method to solve organic pollutions in water. The key to achieve this process is to find and design efficient photocatalytic materials. In this paper, a novel silver-based metal–organic framework (Ag-MOF) [{Ag(H2btc)}{Ag2(Hbtc)}]n (1) (H3btc = 1,3,5-trimesic acid) is designed that exhibits a high performance in the photocatalytic degradation of methylene blue (MB). The process of photocatalytic degradation of MB conforms to pseudo first-order kinetics, and the rate is the fastest at pH 3 (K = 0.2654). Meanwhile, the photocatalytic mechanism of 1 is analyzed by in situ electron paramagnetic resonance (EPR) and ESI-MS spectra. The results are helpful for in situ research of the photocatalytic mechanism of MOFs.

Hierarchical nanostructure of TiO2 nanoparticles/nanorod arrays (TiO2 NPs/NRs) is synthesized and applied in dye-sensitized solar cells (DSSCs) comparing with the TiO2 nanorod (TiO2 NR) arrays and the TiO2 nanoparticles (TiO2 NPs). The TiO2 NP/NR surface morphology is revealed by X-ray diffraction, field emission scanning, and transmission electron microscopy. The power conversion efficiency of NP/NR-based DSSCs (length 3 μm) is improved to 3.47%, which is 2.2 times higher than the NR-based DSSCs (length 3 μm), and rivals the NP-based DSSC (length 5 μm). The high photovoltaic performance was attributed to that the TiO2 NP/NR photoanode has large surface area and exhibits excellent light scattering, allowing for fast interfacial charge transfer and less charge recombination, which are characterized using the UV-vis absorbance spectra, Brunauer–Emmett–Teller (BET) surface area, electrochemical impedance spectroscopy (EIS) measurements, and photoluminescence (PL) spectroscopy. However, further work is needed to overcome the limitations of TiO2 NP/NR and improve the performance of TiO2 NP/NR-based DSSC.