To improve the antimicrobial properties of ZnO, ZnO-supported 13X zeolite (X-ZnO) was prepared via the facile chemical method. Antimicrobial activities of X-ZnO and ZnO were tested against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. X-ZnO showed noticeable antimicrobial activities against E. coli and S. aureus under visible light conditions, especially against E. coli. The minimum inhibitory concentration (MIC) of X-ZnO against E. coli was 0.12–0.24 mg/mL. However, there were still much bacteria alive in the nano-ZnO suspensions at the same concentration. To elucidate the antimicrobial activities of X-ZnO, the average concentration of the total reactive oxygen species (ROS) and Zn2+ ions released from X-ZnO and nano-ZnO were quantitatively analyzed. The obtained results indicated that the average concentration of ROS produced by supported ZnO was much higher than that of nano-ZnO. And the released Zn2+ ions from X-ZnO and nano-ZnO suspensions were much lower than the MIC of Zn2+. Thus, it is believed that the production of ROS in X-ZnO and nano-ZnO suspensions resulted in the difference of antibacterial activities.

Fatigue is an important mechanism for the failure of components in many engineering applications and a significant proportion of the fatigue life is spent in the crack initiation phase. Although a large number of research work addresses fatigue life and fatigue crack growth, the problem of modeling crack initiation remains a major challenge in the scientific and engineering community. In the present work, a micromechanical model is developed and applied to study fatigue crack initiation. In particular, the effect of different hardening mechanisms on fatigue crack initiation is investigated. To accomplish this, a model describing the evolution of the particular dislocation structures observed under cyclic plastic deformation is implemented and applied on randomly generated representative microstructures to investigate fatigue crack initiation. Finally, a method is presented to calculate the S–N curve for the polycrystalline materials. With this work, it is demonstrated how the micromechanical modeling can support the understanding of damage and failure mechanisms occurring during fatigue.

Nine possible native point defects in MgCaSi have been studied by employing density functional theory based ab initio calculations. The complex chemical potential limits are first determined using a two-dimension (∆μMg, ∆μCa) diagram, then the defect formation energies as a function of the atomic chemical potential are gained. The energetic results show that under Mg-rich conditions, the most favorable defect is MgCa rather than MgSi, while CaMg is predominant compared to CaSi under Ca-rich conditions. The bonding energy is first introduced to uncover the intrinsic feature of defect formation energy. The local geometric distortion around CaMg, MgSi, and CaSi antisite defects gradually increases due to the smaller atomic radii from Ca to Mg and Si, showing the important role of the geometrical mismatch. The density of states indicates that the higher stability of CaMg and MgCa originates from the smaller deviation of the Fermi level from the pseudo-gap.

In the present work, the evolution of microstructure and mechanical properties of high-strength low-alloy D6AC steel containing the Ce element was synthetically investigated by means of electron backscatter diffraction, scanning electron microscope, Transmission electron microscope, and tensile and impact tests. The experimental results show that adding a certain amount of Ce into HSLA-D6AC steel can refine grains and martensite laths, as well as increase the fine VC precipitates, which not only enhance the strength of the steel but also improve the toughness and plasticity. Meanwhile, the morphology of martensite in HSLA-D6AC steel changes from twin martensite to dislocation martensite. It is found that after adding Ce, HSLA-D6AC steel exhibits a distinct necking stage in the tensile test, and the impact toughness value increases from 83 to 136 J. With the appearance of some more and deeper homogeneous dimples, the quasi-cleavage fracture transforms into a ductile fracture characterized by microvoid coalescence, demonstrating that HSLA-D6AC steel with the Ce element achieves excellent comprehensive mechanical properties.

To improve the quality of horizontal continuous casting bronze thin slab, especially the end quality of the thin slab, three methods were proposed; (i) using silicon steel sheet at the ends of the traveling magnetic field (TMF), (ii) change in the length of TMF, and (iii) reduction in the ends current intensity of TMF. Then, the effect of these methods on the magnetic field, flow and solidification of thin slab was studied both numerically and experimentally. Results show that the use of silicon steel sheet is the best method to modify the magnetic field intensity distribution. Due to the electromagnetic field shielding effect of silicon steel sheet, when the silicon steel sheet with 150 mm length and 0.5 mm thickness was applied, the magnetic field intensity at the ends of TMF was reduced to about half of the original. However, the magnetic field intensity in the middle of TMF did not change, which assists the elimination of the strong flow of the melt at the ends of the mold and uniform the solidification shell of the melt. Then, the bronze thin slab can be successfully cast without any crack defects at the ends.

X-ray diffraction (XRD), transmission Mössbauer spectroscopy, and vibrating sample magnetometry were used to study the influence of precipitates on the magnetic properties of aged Fe–Cr–Mo alloys. XRD patterns and Mössbauer spectra showed that the alloys have body-centered cubic structure similar to that of α-Fe. Small amounts of precipitates were also identified with relative fraction found to be related to Mo content, aging times, and temperatures. Magnetic measurements showed that the increase in the density of precipitates contributes significantly to the increase in the magnetic hardness of the material. This mechanism is related to a process of pinning of magnetic domain walls. It was also found that saturation magnetization is affected by the Mo content in the alloy. The techniques used in this work were shown to be very useful to understand the mechanisms through which the formation of precipitates affects the magnetic properties of the alloys and may be used as complement to the usual microscopy-based techniques for this purpose.

A “RE-free” and I-phase-containing Mg–8Sn-based alloy system was developed and successfully fabricated through the equal channel angular pressing (ECAP) process. The influence of the Zn/Al mass ratio on the microstructures and mechanical properties of the as-ECAPed Mg–8Sn–(5,6,7)Zn–2(wt%)Al alloys was investigated using an optical microscope, an X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and a universal testing machine. Grain size, dynamic recrystallization behavior, and texture were found to be greatly affected by the Zn/Al mass ratio. Furthermore, the ultimate tensile strength (250 MPa) and elongation (14.5%) of the alloy with a Zn/Al mass ratio of 3 were considerably increased compared to those of the as-ECAPed alloys with Zn/Al ratios of 2.5 and 3.5 (ultimate tensile strength and elongation of 215 MPa and 13% and 184 MPa and 10%, respectively). This significant enhancement was attributed to extensive grain boundary strengthening, precipitation strengthening, and higher work hardening capacity as well as texture randomization. The strength and ductility of the as-ECAPed alloys are also discussed in terms of the I-phase and Mg2Sn formation.

Isothermal compression testing of Ti–5.8Al–3Sn–5Zr–0.5Mo–1.0Nb–1.0Ta–0.4Si–0.2Er titanium alloy is performed on a Gleeble-3500 thermal simulator, and the corresponding microstructures are analyzed to clarify the softening mechanism and participates evolution. A constitutive equation compensated by strain has been established to describe the hot deformation behavior of the alloy. The deformation activation energies are calculated to be 369760.93–699310.86 J/mol in α + β two-phase region and 268030.03–325800.41 J/mol in β single-phase region. At a temperature of 880 °C, the main softening mechanism is the continuous dynamic recrystallization of lamellar α colony, controlled by the mechanical rotation of the sub-grain followed by dislocation climbing and annihilation by diffusion. Meanwhile, the dominant softening mechanism is the discontinuous dynamic recrystallization of β phase during the deformation at temperatures of 920 °C–1080 °C. Silicide containing Er with an average diameter of 20 nm is formed during the water quenching.

To determine the spray forming process parameters of 7075/Al–Si bimetallic gradient composite plate with two gas atomizers, a calculation model of the plate has been established by using the finite element software ANSYS. The effects of different motion trajectory, advance speed, swing cycle and spray center distance on shape, and silicon distribution of deposited plate have been simulated by the APDL programming language. The results show that a smooth and uniform surface is obtained when motion trajectory is in a regular jaggies mode. The deposited plate varies from platform to stepped shape with a center distance increasing from 20 mm to 50 mm; meanwhile, the width of the transition zone decreases gradually. As the period increases to 8 s, the silicon distribution of each layer presents a jagged fluctuation. Both the thickness of the deposited plate and the width of the transition zone decrease as the advance speed increases, except the silicon distribution. Finally, the modeling and simulation of the co-spray formed 7075/Al–Si bimetallic gradient composite plate are validated by experimental investigations and the simulation results are in good agreement with the actual results.

Atom probe tomography and transmission electron microscopy are used to analyze magnetron-sputtered MoS2 films containing Ti and Au/Sb2O3 as a model system for tribological coatings. Transmission electron microscopy characterization showed that the Ti–MoS2 film is dense and featureless whereas Sb2O3/Au–MoS2 film is less dense and have columnar morphology. Three-dimensional atom probe reconstructions revealed that the Ti–MoS2 films have a homogeneous composition and contain about 15 at.% Ti, which is uniformly distributed throughout the MoS2 matrix without any evidence of Ti precipitation. Sb2O3/Au–MoS2 films also showed homogeneous distribution of Sb2O3 throughout the MoS2 matrix and the presence of Au-rich precipitates. The complementary techniques of atom probe tomography and transmission electron microscopy indicate that Ti and Sb2O3 incorporation in the deposition of MoS2 produces amorphous microstructures, whereas the addition of Au forms nano-sized and well-dispersed precipitates.

The thermal expansion behavior of polymer carbon nanotube (CNT) nanocomposites was investigated, and a micromechanical model was proposed to explain the highly nonlinear dependence of the coefficient of thermal expansion of the nanocomposite with CNT content for the CNT/polyimide nanocomposite. The microscopic analysis of CNT/polyimide matrix showed homogeneous dispersion of bundles composed of CNTs. Therefore, the proposed model to predict the thermal expansion behavior of the nanocomposite considered a random, homogeneous distribution of CNT bundles with a hierarchical arrangement of helical CNTs within the polymeric matrix. The CNT bundle morphology influenced the thermal expansion response of the nanocomposite through (i) bundle volume fraction and (ii) degree of helicity, affecting thermo-mechanical properties of the bundle. The effective, homogenized, properties of CNT bundles were determined by the elasticity based solution of the layered cylinder model. Bundle effective properties were used in the micromechanical model implementing the homogenized strain rule of the mixture expression to predict the thermal expansion behavior of nanocomposite in a wide range of CNT volume contents. The proposed micromechanical analytical model was found to correlate closely with the experimental results for polyimide/CNT nanocomposite films as measured using a digital image correlation method.

Phase stability, elastic, and thermodynamic properties of (Co,Ni)3(Al,Mo,Nb) with the L12 structure have been investigated by first-principles calculations. Calculated phonon density of states show that (Co,Ni)3(Al,Mo,Nb) is dynamically stable, and calculated elastic constants indicate that (Co,Ni)3(Al,Mo,Nb) possesses intrinsic ductility. Young’s and shear moduli of the simulated polycrystalline (Co,Ni)3(Al,Mo,Nb) phase are calculated using the Voigt–Reuss–Hill approach and are found to be smaller than those of Co3(Al,W). Calculated electronic density of states depicts covalent-like bonding existing in (Co,Ni)3(Al,Mo,Nb). Temperature-dependent thermodynamic properties of (Co,Ni)3(Al,Mo,Nb) can be described satisfactorily using the Debye–Grüneisen approach, including heat capacity, entropy, enthalpy, and linear thermal expansion coefficient. Predicted heat capacity, entropy, and linear thermal expansion coefficient of (Co,Ni)3(Al,Mo,Nb) show significant change as a function of temperature. Furthermore the obtained data can be used in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys.

Controlling the spatial arrangement of biomaterials and living cells provides the foundation for fabricating complex biological systems. Such level of spatial resolution (less than 10 µm) is difficult to be obtained through conventional cell processing techniques, which lack the precision, reproducibility, automation, and speed required for the rapid fabrication of engineered tissue constructs. Recently, laser-assisted biofabrication techniques are being intensively developed with the use of computer-aided processes for patterning and assembling both living and nonliving materials with prescribed 2D or 3D organization. In this review, we discuss laser-assisted fabrication methods, including laser tweezers, multi-photon polymerization, laser-induced forward transfer (LIFT), matrix assisted pulsed laser evaporation (MAPLE), and laser ablation as well as their applications in biological science and biomedical engineering. These advanced technologies enable the precise manipulation of in vitro cellular microenvironments and the ability to engineer functional tissue constructs with high complexity and heterogeneity, which serve in regenerative medicine, pharmacology, and basic cell biology studies.

Dense ZrB2–SiC nanocomposites were fabricated at 1450 °C by the high-energy ball milling (HEBM) of ZrB2 powder with ZrSi2–B4C–C additives and reactive spark plasma sintering (R-SPS). The sizes of ZrB2 and SiC grains were 80–350 nm, and the phases were homogeneously distributed because of the molecular-level homogeneity of the constituents in ZrSi2 and the homogeneous mixing of the raw powders by HEBM. The deformation of ZrSi2 or the reactions between the additives during R-SPS did not strongly promote the densification. Fine and homogeneously distributed ZrB2 and SiC particles formed by HEBM and R-SPS were the major reasons for the low temperature densification. The fine particles which had high surface energy provided the driving force for densification at low temperatures. Also, the fine SiC grains suppressed the growth of ZrB2 grains during densification. The 4-point bending strength of the composites sintered at 1500 °C was 354 MPa.

Prompted by the success in functionalizing 2D sheets of MoS2 and MoSe2 by their reaction with organic halides, we have investigated the functionalization of layered tungsten chalcogenides, WS2, WSe2, and WTe2, by their reaction with substituted iodobenzenes as well as fluorophores based on pyrene and coumarin. Carbon–chalcogenide bonds are formed readily in the case of metallic chalcogenides while there is need for the Pd(0) catalysts in the case of insulating chalcogenides. Thus, the formation of carbon–chalcogen (S, Se, and Te) bonds is accomplished with the metallic 1T as well as the semiconducting 2H phases of the tungsten chalcogenides. Functionalization in the case of substituted iodobenzenes is favored by the electron withdrawing groups in the benzene ring. Interestingly, functionalization has been successful with other insulating layered chalcogenides such as GaS and GaSe. Reaction with organic halides emerges as a general method for the covalent functionalization of chalcogenide nanosheets, suggesting the possible use of this strategy to functionalize various chalcogenide structures.

Boron carbide (B4C) ceramic particles were used as reinforcement material to produce aluminum (Al) matrix composites by squeeze casting method. Four different B4C contents as 0, 3, 5, and 10 wt%, and three different squeeze pressures as 0, 75, and 150 MPa were used in which the samples consisted of pure Al without B4C and the samples obtained without applying pressure were used as control samples. To determine the effect of squeezing pressure and the amount of B4C added on machinability and mechanical properties, average chip length and surface roughness of the samples were evaluated and hardness measurements were accomplished, yield and ultimate tensile strengths were determined, respectively. Also, the changes in density and microstructure were investigated. B4C reinforcement was found to decrease the average chip length and density of the samples while increasing the hardness and surface roughness. On the other hand, application of squeeze pressure had a positive effect on the densification and mechanical properties of the samples.

The nucleation and growth of Al on 7 × 7 and $\sqrt 3 \times \sqrt 3$R30 Al reconstructed Si(111) that result in strain-free Al overgrown films grown with an atomically abrupt metamorphic interface are compared. The reconstructed surfaces and abrupt strain relaxations are verified using reflection high-energy electron diffraction. The topography of evolution is examined with atomic force microscopy. The growth of Al on both the surfaces exhibits 3D island growth, but the island evolution of growth is dramatically different. On the 7 × 7 surface, mounds formed are uniformly distributed across the substrate, and growth appears to proceed uniformly. Alternatively, on the $\sqrt 3 \times \sqrt 3$R30 surface, Al atoms exhibit a clear preference to form mounds near the step edges. During Al growth, mounds increase in size and number, expanding out from step edges until they cover the whole substrate. Consistent expression of a mounded nucleation and growth mode imparts a physical limitation to the achievable surface roughness that may impact the ultimate performance of layered devices such as Josephson junctions that are critical components of superconducting quantum circuits.

In situ and ex situ neutron reflectivity is used to characterize annealed regioregular-P3HT/PCBM bilayers. In situ annealing of a 20 nm PCBM/35 nm P3HT bilayer at 170 °C reveals rapid mixing of PCBM and P3HT to produce a polymer-rich layer that contains around 18–20% PCBM. Samples with three different thicknesses of P3HT layer are ex situ annealed at 140 °C. This again reveals migration of PCBM into the P3HT and vice versa, with the polymer-rich layer in the 20 nm PCBM/35 nm P3HT sample containing 19% PCBM. Complete migration of the entire PCBM layer into the P3HT layer is observed for a 20 nm PCBM/80 nm P3HT bilayer. The robustness of fitted model composition profiles, in comparison with real-space imaging of sample surface morphology and previous work on annealed P3HT/PCBM bilayer compositions, is discussed in detail.

The absorber layers for chalcopyrite solar cells were fabricated by selenization of the stacked metal layers (SML). Co-sputtering and sequential sputtering methods were utilized to prepare the SML, and the variation of the stacking sequences and the effect of each stacked layer thickness were investigated. The stacking sequence of In/CuGa⋯In/CuGa was found having advantages in the SML growth and the average size of indium hillocks might be tailored by changing the thickness of each stacked layer. The SML in the stacking mode of In/CuGa⋯In/CuGa prepared while the thickness for each indium layer fixed at approximately 83 nm exhibited the desired morphology with evenly distributed indium hillocks in small diameters. The selenized ${\rm{CuI}}{{\rm{n}}_x}{\rm{G}}{{\rm{a}}_{1 - x}}{\rm{S}}{{\rm{e}}_2}$ (CIGS) layer showed a smooth surface and largest grain size with phase segregation being suppressed effectively. The hole mobility of the best CIGS layers reached 8.36 cm2/V s.