Contamination by bacterial biofilms has a strong negative impact, especially on the surface of prostheses, implants, pins, and other medical-surgical devices. To prevent their formation, one of the alternatives is the modification of the metal surface incorporating silver by low-energy ion implantation, thus avoiding initial bacteria adhesion to the modified surface and further development of the biofilm. The bactericidal properties of silver atoms incorporated on commercially pure titanium surfaces by low-energy ion implantation (4 keV) were evaluated. The surface modifications were analyzed by Rutherford backscattering spectrometry, glow discharge-optical emission spectroscopy, contact angle measure, optical profilometry, and X-ray photoelectron spectroscopy. The microbiological assays were conducted by using Escherichia coli (E. coli). The results demonstrated a reduction on bacterial counting. No toxic effect of silver was detected on human MG-63 cells. The choice of parameters to obtain a bactericidal and nontoxic biomaterial for human cells should consider the ideal combination “energy + silver concentration”. Therefore, it can be considered for industrial application.

A computational model for the evaluation of the thermomechanical effects that give rise to the catastrophic optical damage of laser diodes has been devised. The model traces the progressive deterioration of the device running in continuous wave conditions. The local heating of the active layer locally leads to the onset of the plastic regime. As a result, dislocations and threads of dislocations grow across the active layers and lead to rapidly growing temperatures in the quantum well. The poor power dissipation under these conditions has been identified as the key factor driving the final degradation of the laser.

Low-cost, earth-abundant magnetocaloric materials (MCMs) are required for energy-efficient, green, and affordable magnetic cooling technology. We investigated the magnetic and magnetocaloric properties of rare-earth-free Fe75−xCrxAl25 (19≤x≤25) arc-melted alloys. The Curie temperature (Tc) of these alloys could be tuned from 220 K up to room temperature by Cr additions. The relative cooling power/US$ was found to be superior to other promising MCMs. Fe50Cr25Al25 ball-milled powders, with an average particle size of ~25 nm, were used to prepare magnetic fluid. Maximum cooling (ΔT) of 5.4°C was observed for Fe50Cr25Al25-based fluids.

The Fe–18.6% Ga alloy (at.%) has a high magnetostriction and an excellent piezomagnetic (PZM) property. However, Fe–Ga has a poor ductility and the addition of B helps to improve this property. The magnetostriction of the Fe–Ga alloy is not appreciably improved by the addition of B; however, the PZM behavior of Fe–Ga–B is unknown up to now. Then, an Fe–Ga alloy with 2% of B was produced to evaluate the effect of boron addition on the PZM property of the Fe–Ga alloy. The PZM force sensing performance coefficient d33* decreased, but the maximum sensitivity is reached for a fixed magnetic field. In addition, d33* values are among 2 and 5 mT/MPa, which is sufficient for many applications. A better ductility compared to Fe–Ga and a good sensitivity at constant field, makes the alloy Fe–Ga–B a good candidate for application as force sensors up to stresses of 80 MPa.

7-Decyl-2-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10) is a soluble organic semiconductor that can afford high mobility organic thin-film transistors (OTFTs). The material exhibits inherent high layered crystallinity due to the formation of bilayer-type layered-herringbone packing that involves nearly independent π-electron core layers and alkyl-chain layers within the crystals. Here, we discuss that the bottom-gate/top-contact OTFTs composed of single-crystalline Ph-BTBT-C10 channel layers exhibit noticeable effects in the device characteristics caused by the highly insulating nature of the alkyl-chain layers. Notable layer-number (n) dependence was observed in the nonlinear current–voltage characteristics and the device mobility (2–14 cm2/Vs, with TFT ideality factor 15–46%, mainly due to large threshold voltages), which can be clearly ascribed to the tunneling-based interlayer access resistance across the alkyl-chain layers. The gated-four-probe measurements of single-crystalline OTFTs also revealed quite high mobility more than 40 cm2/Vs along the channel semiconducting layer, whereas highly insulating effects due to the alkyl-chain layers were also apparent as the large hysteresis in the gate-off states of OTFTs. We discuss the whole features of the tunneling-based access resistance in the device operations of single-crystalline OTFTs, on the basis of comparison between experimental results and model simulations.

As high-entropy alloys (HEAs) are being actively explored for next-generation structural materials, gaining a comprehensive understanding of their creep, fatigue, and fracture behaviors is indispensable. These three aspects of mechanical properties are particularly important because (i) creep resistance dictates an alloy’s high-temperature applications; (ii) fatigue failure is the most frequently encountered failure mode in the service life of a material; (iii) fracture is the very last step that a material loses its load-carrying capability. In consideration of their importance in designing HEAs toward applicable structural materials, this article offers a comprehensive review on what has been accomplished so far in these three topics. The sub-topics covered include a comparison of different creep testing methods, creep-parameter extraction, creep mechanism, high-cycle fatigue S–N relation, fatigue-crack-growth behavior, fracture toughness, fracture under different loading conditions, and fractography. Directions for future efforts are suggested in the end.

Room-temperature liquid metals, such as eutectic gallium–indium–tin (galinstan), dispersed in a polymer matrix present unique potential as conductors that may have minimal influence on the host polymer mechanical performance while providing enhanced electrical performance. Work described herein systematically evaluates the influence of uncured polydimethylsiloxane (PDMS) viscosity and galinstan loading on final dispersion viscosity and cured modulus. Dispersions of up to 80 vol% galinstan were obtained with relative permittivity values up to 170 that otherwise exhibited similar uncured rheological changes to a solid filler. Cured galinstan-in-PDMS dispersions, however, exhibited a reduced stiffness increase with respect to the host polymer relative to a solid filler. At a critical PDMS viscosity and metal, loading phase inversion to a conductive PDMS-in-metal dispersion was observed. It is anticipated that this work will enable the development of liquid metal polymer composites with independently controlled mechanical and electrical properties for a wide variety of stretchable electronic applications.

Using time-resolved laser-scanning confocal microscopy and ultrafast optical pump/THz probe spectroscopy, we measure photoluminescence (PL) and THz-conductivity in perovskite micro-crystals and films. PL quenching and lifetime variations occur from local heterogeneity. Ultrafast THz-spectra measure sharp quantum transitions from excitonic Rydberg states, providing weakly bound excitons with a binding energy of ~13.5 meV at low temperatures. Ab-initio electronic structure calculations give a direct band gap of 1.64 eV, a dielectric constant of ~18, heavy electrons, and light holes, resulting in weakly bound excitons, consistent with the binding energies from the experiment. The complementary spectroscopy and simulations reveal fundamental insights into perovskite light-matter interactions.

Biomineralization is a natural concept to alter the mechanical properties of soft matter. Mimicking this concept became desirable with a resulting great variety of approaches toward realizing functional hybrid materials. Vapor-phase infiltration (VPI), a solvent-free approach, is complementary to solution-based processes and often provides hybrid materials with a different chemical nature. This article overviews the evolution of VPI from a curiosity-driven alternative way to mimic biomineralization toward its application in functional materials design. Even though still in infancy, the rapidly growing interest shows promise for upcoming innovative applications of VPI in a great variety of research and development directions.

Direct arylation polycondensation (DArP) is an emerging synthetic method of producing conjugated polymers in an environmentally benign and cost-effective manner. We now report the synthesis of hole-transporting conjugated polymers, namely, DPP-OMe (Mn = 7.9 kg/mol) and DPP-F (Mn = 12.6 kg/mol), under microwave-assisted DArP conditions. These two polymers and the previously synthesized 3,6-Cbz-EDOT were evaluated as hole-transporting materials in mesoscopic perovskite solar cells. 3,6-Cbz-EDOT synthesized by DArP exhibited higher hole mobility and better photovoltaic properties than that synthesized by the Stille polycondensation. Moreover, chemical dopants improved the short-circuit current density (Jsc) and fill factor.

Due to the special crystal structures and electron configurations, high-entropy alloys (HEAs) are expected to have favorable activities for electrocatalytic reactions. In this paper, a set of oxygen evolution reaction (OER) criteria are applied for the HEA-based electrocatalyst design. Specifically, FeNiMnCrCu HEA is predicted to have a better OER performance than the baseline FeCoNiCrAl HEA. To demonstrate this design approach, both FeNiMnCrCu and FeCoNiCrAl samples are prepared and tested. Their crystal structures and electrocatalytic performance are examined. This paper demonstrates the potential of using finely tuned HEAs for OER applications.

The development of advanced fuel fabrication technologies is important for developing accident-tolerant fuels and engineering fuels for safer and more effective nuclear energy systems. In this work, commercial-size uranium dioxide (UO2) fuel pellets with a theoretical density of 95% were consolidated by spark plasma sintering (SPS) at 1600°C for 5 min. Systematic investigations suggest uniform densification and stoichiometric UO2 with an ideal fluorite structure across the commercial-size fuel pellet, but with a distributed grain structure because of non-uniform distribution of temperature during sintering. This work demonstrates a great potential of using SPS for fabricating nuclear fuels at a cost-effective manner.

A series of Ba-modified MnCeOx/TiO2 catalysts were prepared by a wet impregnation method and tested for selective catalytic reduction (SCR) of NO with NH3 at low temperature. The results showed that Ba additives obviously improved the catalytic performance of the MnCeOx/TiO2 catalyst for NH3-SCR, and the BaMnCeOx/TiO2 catalyst with 3 wt% BaO exhibited the optimal catalytic performance. Moreover, the introduction of Ba also improved the resistances toward water vapor and SO2 of catalysts. The N2 adsorption, H2-TPR, and X-ray photoelectron spectroscopy results showed that the addition of Ba increased the specific surface area, redox properties, and concentrations of surface Mn4+ and chemisorbed oxygen of catalysts. Furthermore, NH3-TPD and NO-TPD were used to investigate the absorption of NH3 and NO on the catalyst. The results revealed that although the introduction of Ba significantly promoted the adsorption of NO, it also inhibited the adsorption of NH3. Consequently, the catalytic performance of MnCeOx/TiO2 was greatly improved with the Ba additives.

Valvular heart diseases lead to over 300,000 heart valve replacements worldwide each year. Bioprosthetic heart valves (BHVs), derived from glutaraldehyde (GLUT) crosslinked porcine or bovine pericardium, are often used. However, valve failure can occur within 12–15 years due to progressive degradation and/or calcification. Being innovated by previous amino reagent studies used for GLUT detoxification and carbodiimide [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, EDC] chemistry, in this study, we developed a new fabrication method that utilizes exogenous amino donor arginine or lysine carbodiimide combined treatments to better stabilize the extracellular matrix of porcine pericardium. The carboxyl group density, amine content, differential scanning calorimetry, collagenase and elastase degradation, calcification by rat subdermal implantation, cytotoxicity, and platelet adhesion were characterized. We demonstrated that exogenous amino donor carbodiimide combined treatment for pericardiums had better resistance to elastase degradation (1.63 ± 0.11% and 1.44 ± 0.24% in arginine or lysine versus 3.68 ± 0.16% and 3.04 ± 0.11% in GLUT and GLUT/EDC control) and calcification (0.624 ± 0.193 and 0.637 ± 0.213 Ca µg/mg tissue in arginine or lysine versus 1.610 ± 0.124 and 1.512 ± 0.075 Ca µg/mg tissue in GLUT and GLUT/EDC control). This new strategy combined arginine or lysine and carbodiimide crosslinking would be a promising method to produce more robust BHVs with better structural stability and anticalcification property.

The microstructure evolution of the directionally solidified NiAl–Cr(Mo) planar eutectic lamellar structure was studied at 1150 °C and times of up to 400 h. The planar eutectic lamellar structure is obtained at the withdrawal rate range of 2.5–7.5 μm/s. The interlamellar spacing decreases gradually with increasing the withdrawal rate. The lamellar termination (like angular or smooth) commonly exists in the as-DS alloy. After high temperature treatment, the lamellar structure at 2.5 μm/s (interlamellar spacing, 3.7 μm) is almost stable, only a little migration of termination occurs at 400 h. When the withdrawal rate increases to 4.5 μm/s, the coarsening and migration of termination occur at 200 h. The adjacently coarsened terminations assemble when the coarsening processes to a certain degree, thus resulting in the formation of the blocky Cr(Mo) phase. Similarly, the above instable phenomenon occurs at 7.5 μm/s. The relevant instability mechanisms are discussed.

For one-dimensional nanomaterials, the performances are strongly related to the diameters, lengths, morphologies, and structures, implying that it is of great significance to understand the related growth mechanisms and thus to achieve the desired nanostructures. Thermal oxidation of copper has been widely used to fabricate CuO nanowires (NWs), whereas the growth mechanism still remains controversial in spite of the extensive investigations. Therefore, this review aims to offer a critical discussion about the growth mechanisms. First, the effects of different growth conditions on the growth of CuO NWs are introduced for basic understanding. Subsequently, the proposed mechanisms in different literature studies, i.e., the vapor–solid, self-catalyzed growth, stress-induced growth, stress grain boundary (GB) diffusion, and oxygen concentration gradient, are discussed and summarized. It seems that the combination of “stress GB diffusion” and “oxygen concentration gradient” mechanisms could be relevant for the growth of CuO NWs via thermal oxidation of copper.

Here, we report thiol-free thermal-injection synthesis of chalcopyrite (CuFeS2) nanocrystals (NCs) using iron (II) bromide (FeBr2), copper (II) acetaylacetonate (Cu(acac)2), and elemental sulfur (S). Controlled reaction temperature and growth time yield stable and phase-pure ternary CuFeS2 NCs exhibiting tetragonal crystal structure. With increasing growth time from 1 to 30 min, absorption peak slightly red shifts from 465 to 490 nm. Based on spectroscopic ellipsometry analysis, three electronic transitions at 0.652, 1.54, and 2.29 eV were found for CuFeS2 NC film. Also, CuFeS2 NC thin films are incorporated as hole transport layers in cadmium telluride solar cells reaching an efficiency of ~12%.

The phase stability, equilibrium lattice parameters, mechanical properties, and chemical bonding of M2B and M2B0.75C0.25 (M = Fe, Cr, W, Mo, Mn) were studied using first-principles calculations within density functional theory. These compounds are thermodynamic stability structures, and the M2B0.75C0.25 stability is worse than that of M2B. The equilibrium lattice parameters are consistent with other available experimental and theoretical data. Stress–strain and Voigt–Reuss–Hill approximations were used to estimate the elastic constants (Cij) and moduli (B, G, E), respectively. The bulk modulus and the ductility increased by adding an appropriate amount of C to the M2B. The compound hardness was studied using a theoretical method based on the work of Tian. The chemical bonding of these compounds was estimated using the Mulliken population analysis and density of states, and the results indicate that the bonding behaviors of these compounds are combinations of metallic and covalent bonds.

In this paper, we will discuss stability and reliability requirements of organic electronic devices and evaluate different encapsulation approaches enabling stable organic ultra-thin and stretchable devices. We highlight the differences in requirements and encapsulation approaches for applications, including organic light emitting diode (OLED) displays, OLED lighting, photovoltaics, and sensors. Stability and reliability requirements addressed in this paper cover light management, mechanical characteristics, chemical compatibility, form factors, and durability. While flexible organic electronic devices have already been demonstrated and commercialized, so far only prototypes of ultra-thin and stretchable devices have been demonstrated. The technological progress is promising and by identifying the gaps between prototyping and product realization, we intend to stimulate further research and development in this area.