The hydroxyapatite nanoparticles (nHAPs) were synthesized rapidly by the self-assembled dual-frequency ultrasonic method. The ultrasonic time and power effect on the morphology and phase composition of nHAPs were investigated through field-emission scanning electron microscopy (FE-SEM), X-ray diffraction, energy dispersive spectrometer (EDS) spectrometer, and Fourier transform infrared spectroscopy, which showed that the most uniform nanoparticles were obtained when the ultrasonic time was 30 min and the ultrasonic power was 280 W. Cytotoxicity and hemolysis tests showed that an indistinctive cytotoxic effect was within the concentration of 25–400 μg/mL and the hemolytic ratio was below 2.0% at concentration of 25–200 μg/mL, respectively, revealing a good biocompatibility of nHAPs. By loading tetracycline hydrochloride onto nHAPs spheres, the drug release results showed that the drug loading and encapsulation efficiency were (26.34 ± 2.99)% and (52.68 ± 5.98)%, respectively. The drug-loaded sample shows a slow-release property, indicating that nHAPs may be promising as drug carriers.

Chalcopyrite quantum dots (QDs) have emerged as a safe alternative to cadmium-based QDs for bio-applications. However, the research on AgInS2 chalcopyrite QDs has not been widely explored in terms of their toxicity. Herein, we report a synthesis of biocompatible AgInS2/ZnS QDs via a greener approach. The emission intensity of the as-synthesized AgInS2 core QDs was enhanced 2-fold after the ZnS shell growth. X-ray diffraction revealed the tetragonal crystal structure of QDs, and high-resolution transmission electron microscope images show that the QDs are spherical in shape and crystalline in nature. Cell viability assays conducted on different cell lines, such as HeLa, A549, and BHK-21 cells, indicated that AgInS2/ZnS QDs are least toxic at a QD concentration range of 100 µg/mL. The fluorescent microscope analysis of A549 cells incubated with AgInS2/ZnS QDs shows that the QDs were accumulated in the cell membranes. The as-synthesized AgInS2/ZnS QDs are less toxic and eco-friendly, and can be used for biolabeling.

Porosity-graded, conductor- and binder-free porous FeS2 films through the entire thickness were deposited by spray pyrolysis. The film layers deposited at 15 versus 10 L/min are grown in different modes. The film layer deposited at 15 L/min showed Frank–van der Merwe layer-like growth mode whereas the one deposited at 10 L/min showed island growth mode. These growth modes lead to the formation of large pores on the electrolyte side and small ones on the substrate side of the film deposited using 15 and 10 L/min, sequentially. The porosity-graded films showed discharge capacities at C/10 of 879 mA h/g and 754 mA h/g for the 5th and 20th cycles, respectively. Such capacity values are superior to the literature findings for FeS2 powders and nongraded films mixed with conductor and binder additions.

A novel and highly efficient Ag3VO4/C3N4/reduced TiO2 microsphere composite was obtained through a hydrothermal and depositional process. The microstructure, individual components with different proportions, and optical properties of the ternary nanocomposites were intensively studied. The prepared ternary composites exhibited superior photocatalytic performance of degradation of methylene blue compared with single component and S1 (C3N4/reduced TiO2) binary composites, demonstrating that the introduction of Ag3VO4 into g-C3N4/r-TiO2 can effectively improve the photocatalytic activity. Recycling experiments confirmed that the nanocomposites exhibited superior cycle performance. The enhanced capability could be attributed to a synergetic effect including the formation of heterojunction, large surface area, improved light absorption, matched energy band structure, and the improved separation efficiency of photogenerated charges coming from dual Z-scheme structure. Particularly, the introduction of Ag3VO4 makes the dual Z-scheme charge transfer pathway completed with improved separation efficiency and stronger redox ability of photogenerated electrons and holes. The work provides a promising method to develop a new dual Z-scheme photocatalytic system to remove environmental pollutant.

Recent molecular dynamics simulations revealed that 〈c + a〉 dislocations in Mg were prone to dissociation on the basal plane, thus becoming sessile. Basal dissociation of 〈c + a〉 dislocations is significant because it is a major factor in the limited ductility and high work-hardening in Mg. We report an in situ transmission electron microscopy study of the deformation process using an H-bar-shaped thin foil of Mg single crystal designed to facilitate 〈c + a〉 slip, observe 〈c + a〉 dislocation activity, and establish the validity of the largely immobile 〈c + a〉 dislocations caused by the predicted basal dissociation. In addition, through detailed observations on the fine movement of some 〈c + a〉 dislocations, it was revealed that limited bowing out movement for some non-basal portions of 〈c + a〉 dislocations was possible; under certain circumstances, i.e., through attraction and reaction between two 〈c + a〉 dislocations on the same pyramidal plane, at least portions of the sessile configuration were observed to be reversed into a glissile one.

Until recently, mesoporous silica (MPS) particles have been successfully used in various biomedical applications including drug delivery. In the past decades, the research on MPS shifted sharply to gene delivery owing to its biocompatible, mesoporous structure that allows for loading oligonucleotides, shielding in the bloodstream, and delivering them to patient cells’ cytoplasm to stop cells’ genetic transcription. Until now, researchers faced several unique challenges and MPS, as oligonucleotide vectors, could not reach the clinical stage. In this study, material-related challenges were endeavored to overcome by a combined particle synthesis/oligo-loading strategy. DNA-encapsulated silica/polyethylene glycol (PEG) hybrid xerogels were synthesized at one step, via sol–gel technique. The xerogels were grinded into particles and characterized by X-ray diffraction, scanning electron microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, and gas adsorption analysis. The results demonstrated that uniform oligo-loaded silica/PEG hybrid xerogels could be synthesized without surface modification. Oligonucleotides were encapsulated inside the whole porous network, rather than attached only to particle surfaces as such in the conventional route. The results showed that PEG incorporation led to formation of monolithic xerogels, which could be grinded into spherical particles (557 ± 110 nm) with well-defined edges. Due to grinding, PEG chains were present both in the interior and on the surface of the particles. 10% PEG incorporation into silica precursor (tetraethyl orthosilicate) increased the resistance of DNA-encapsulated silica against protein degradation. In the overall sol–gel-derived silica/PEG hybrid materials were revealed as potential candidates for gene delivery applications such as RNA interference therapies.

This article reports on the growth kinetics of cerium oxide (CeO2) nanoparticles prepared via a sintering method. By varying the sintering temperatures and periods of time, particle size of CeO2 nanoparticles was tuned from 11 to 100 nm. Ostwald ripening mechanism prevails in the growth process, and the growth kinetics is determined to follow an equation, D5 = 16.25 + 3.6 × 1020 exp(−344.20/RT) in the temperature range of 700 to 1000°C. After dispersing Pt on CeO2 nanoparticles, the size effect for the catalytic performance of the CO oxidation reaction was researched. When temperature and period of time are set at 700 °C and 2 h, respectively, dispersion of Pt onto CeO2 nanoparticles led to the largest quantity of chemisorbed oxygen species on the surface and the best catalytic performance. The findings reported here would provide a feasible path for the preparation of advanced catalysts in the future and moreover to discover novel size-dependent supports for many catalytic applications.

The configurations associated with the dissociative adsorption of water on a variety of low-coordinated sites of MgO(100) surfaces, including corners, steps, MgO vacancies, and kinks on 〈010〉 steps, have been studied and assigned by combining infrared spectroscopy and ab initio calculations. Three kinds of MgO powders were examined: powders of very high specific surface area prepared by chemical vapor synthesis and well-defined cubic smoke particles obtained by combustion in either 20:80 or 60:40 O2:Ar mixtures, the latter one involving less defects and smaller particles. It appears that an imperative requirement to obtain a precise characterization of the reactive behavior of defects is to keep the samples in ultra–high vacuum conditions and to control the water partial pressure finely.

A supersaturated single-phase Cu–26 at.% Co alloy was produced by high-pressure torsion deformation, leading to a nanocrystalline microstructure with a grain size smaller than 100 nm. The nonequilibrium solid solution decomposed during subsequent isothermal annealing. In situ high-energy X-ray diffraction was used to map changes linked to the separating phases, and the development of a nanoscale Cu–Co composite structure was observed. To gain further information about the relationship of the microstructure and the mechanical properties after phase separation, uniaxial tensile tests were conducted on as-deformed and isothermally annealed samples. Based on the in situ diffraction data, different isothermal annealing temperatures were chosen. Miniaturized tensile specimens with a round cross section were tested, and an image-based data evaluation method enabled the evaluation of true stress–strain curves and strain hardening behavior. The main results are as follows: all microstructural states showed high strength and ductility, which was achieved by a combination of strain-hardening and strain-rate hardening.

Enthalpy increments, $\Delta _{298}^T{H^0}$, for highly nonstoichiometric SrFeO3−δ (δ = 0.18–0.41) were obtained between 373 and 1273 K in air using drop calorimetry. The analysis of the $\Delta _{298}^T{H^0}\left( T \right)$ dependence at lower temperatures allowed evaluating the enthalpy of tetragonal to cubic ${{I4} / {mmm}} \,{\tf="TeX CM Bold Maths Symbols"\char33}\, Pm\bar{3}m$ phase transition at 560 K, 1.57 kJ/mol, and the Maier–Kelley function for $\Delta _{298}^T{H^0}\left( T \right)$ of tetragonal SrFeO3−δ (space group ${{I4} / {mmm}}$). Combined investigation of oxygen nonstoichiometry $\bolddelta \left( T \right)$ dependence, measured by thermogravimetry, and higher-temperature $\Delta _{298}^T{H^0}\left( T \right)$ of cubic SrFeO3−δ (space group $Pm\bar{3}m$) yielded the temperature-dependent reduction (oxygen release) enthalpy, $\Delta H_{{\rm{red}}}^{\rm{0}}$. Calorimetrically-determined $\Delta H_{{\rm{red}}}^{\rm{0}}$ of SrFeO3−δ increases from 65 ± 7 kJ/mol O at 873–973 K to 84 ± 7 kJ/mol O at 1073–1273 K, which may indicate that the short-range vacancy ordering in SrFeO3−δ is hampered at higher temperatures.

In the present work, mechanical, tribological, and electrochemical behaviors of Al Alloy 6061–(0–10) % B4C–(0.25–1.2) % graphene nanoplatelets (GNPs) composites, prepared by a combination of solution mixing and powder metallurgy, were investigated. Properties such as hardness, compressive strength, wear rates, and coefficient of friction (COF) were used to investigate the effects of GNPs on mechanical and self-lubricating tribological behavior. The corrosion resistance of composites was investigated using potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and EDS mapping were employed to study the distribution, the fracture profile, and wear mechanism. The AA 6061–10% B4C–0.6% GNPs composites exhibited sharp increase in hardness and compressive strength and significant decrease in wear rates and COF. However, for GNPs contents exceeding over 0.6 wt%, mechanical properties and wear performances deteriorated. Pulling out of sheared pultruded GNPs was observed during the fracture of composites. Worn surfaces of GNPs-containing composites showed the smeared graphene layer with some macro-cracks exhibiting delamination wear. It was found that the corrosion inhibition efficiency of GNPs was more pronounced in H3BO3 environment than in NaCl solution.

In this work, two types of zinc adipate β-nucleating agents, Adi-Zn(OH)2 (1:1) and Adi-ZnO (1:1), for polypropylene (PP) were prepared and their performances were evaluated and compared with commercial β-nucleating agent (named CNA). Results showed that Adi-Zn(OH)2 (1:1) was more effective in promoting PP to form β-crystals and improving the impact strength of PP in the range of nucleating agent addition (0–0.4 wt%). Based on these findings, the ratio of adipic acid to zinc hydroxide and the nonisothermal crystallization kinetics of the optimum ratio of adipic acid to zinc hydroxide were systematically studied; results showed that at 0.2 wt%, Adi-Zn(OH)2 (1:2), the nucleated PP displayed the highest impact strength, which was 2.6 times that of pure PP and 42% higher than that of CNA. Besides, Adi-Zn(OH)2 (1:2) could also afford to induce the formation of a high content of β-crystals and shorten the crystallization half time (t1/2) and accelerate the crystallization of PP.

There is no agreement regarding which solvent is more suitable to obtain sol–gel–derived titania (TiO2) samples with an enhanced photocatalytic behavior. Furthermore, the solvent effect on the preparation of TiO2-RGO (reduced graphene oxide) nanocomposites has not been published yet and could be an attractive experimental strategy to modulate structure and properties. On the basis of these observations, TiO2-RGO nanocomposites were fabricated in this study. It was evaluated for the influence of using either isopropyl (IsoprOH) or ethyl (EtOH) alcohol on the textural and photocatalytic properties of the prepared materials. The use of IsoprOH led to samples with smaller crystallite size, narrower apparent band gap, smaller isoelectric point, larger adsorption capacity, and higher photocatalytic activity. In addition, the incorporation of RGO into TiO2 greatly improved the adsorption capacity and photocatalytic activity of the latter. However, the optimal loading of RGO to prepare composites with enhanced photocatalytic activities was 1 wt%. This finding can be related to the stacking of RGO sheets when concentrations above 1 wt% are used, which could prevent UV light to reach the TiO2 particles and also decrease the photocatalytic capacity of the composites. Moreover, materials with RGO concentration above 1 wt% could exhibit a highly negatively charged surface, which may decrease the separation of the generated electron–hole pairs and lead to faster recombination rates of charge carriers.

Poly(ethylene glycol) (PEG)-based materials can potentially be used as biomechanical matrices in regenerative medicine and tissue engineering implants including the replacement of intervertebral (IV) disks. Glycerol and other generally recognized as safe (GRAS) plasticizers (low-MW PEG, propylene glycol, and sorbitol) were added to the bulk PEG matrix and gelled using chemical and photochemical methods at different temperatures (21, 37, 59, and 80 °C) and pressures (0 and 90 MPa gauge) settings, and their compression testing properties were acquired and analyzed. Surface incorporation of custom-made bioactive glass particles shortened the blood clotting time (78% compared to no glass particles), while alginate and laponite additives improved the gel’s mechanical properties to 645 kPa compressive modulus, 12% yield strain, and 79 kPa yield strength. This IV disk-modeled hydrogel system endured the cyclic loading and unloading tests at 4% compressive strain indicative of an elastic response, but required improvement to its biomechanical tolerance for downstream bioengineering applications.

Concurrently assessing localized residual stresses and mechanical properties in cases where there are gradients in stresses and properties (such as those resulting in metallic alloys from shot peening processes) is challenging. Most indentation-based stress measurements assume uniform properties, which is not necessarily the case in this common industrial process. By using the energy envelope describing the total work of indentation by a load–displacement curve from instrumented indentation, localized residual stresses after shot peening were evaluated experimentally. A framework is developed to describe the appropriate indentation depth at which to assess properties that effectively define the volumetric resolution of the method. The residual stresses predicted via the nanoindentation experiment and energy analysis were validated with X-ray measurement of residual stresses on a shot-peened 52100 steel. The energy method can be applied directly from the indentation load–displacement curve without considering the contact area.

Ultra-rapid microwave sintering of ceramics has been recently demonstrated by the authors. In the experiments with oxide ceramic samples carried out in a 24 GHz gyrotron system for microwave processing of materials, full density was achieved in the sintering processes with a duration of the high-temperature stage of one to several minutes and zero hold at the maximum temperature. The implementation of the ultra-rapid microwave sintering processes was made possible due to fast and efficient control over the temperature of the materials and the supplied microwave power. The absorbed microwave power density was typically in the range of 10–100 W/cm3, which is within the same order of magnitude as the power of Joule heat in the DC electric field–assisted flash sintering processes. At this power level, a thermal instability is triggered by the volumetric heating, which results in a drastic enhancement of mass transport. In addition, possibility of ultra-rapid microwave sintering of powder metals has been demonstrated within a model accounting for the effective electromagnetic properties and resonant absorption effects.

An analytical research is developed using the averaging technique of composites for the macroscopic behaviors of porous shape memory alloy (SMA) beam with different porosity under pure bending. The whole material is regarded as a composite beam of porous SMA and dense SMA, in which the component fractions of the porous SMA show gradient changes over geometric dimension. To get the theoretical solution of such material under pure bending, the Mises yield theory and the ideal elastoplastic model are used to describe the phase transition of the material. The macroscopic behaviors of the porous SMAs beam with different porosity are then simulated using the averaging technique of composites. Examples for a porous SMA beam with gradient porosity from 0 to 50% considering the tension compression asymmetry of the SMAs are then supplied; the results show that after transformation the stress distribution in the whole material is lower than in the case of the pure elastic gradient porous materials, and for different part of the SMA with different porosity shows different strength characters.

Graphene oxide (GO) is a promising material in improving the corrosion resistance properties of metals. This improvement significantly relies on the microstructure and electrical properties of GO, which nevertheless is rarely studied. Here, multiscale GOs with different flake sizes and oxidation degrees were fabricated and incorporated into waterborne alkyd resin (AR). The physical and chemical structures of GO and AR/GO composites were characterized in detail. Multiscale GOs are successfully prepared, and the corrosion resistance of AR/GO coatings is measured by electrochemical workstation. Electrochemical experiments indicate that GOs with larger flake sizes have excellent barrier properties due to the shielding effect; GOs with appropriate oxidation degrees could effectively improve the dispersion of GO and avoid the conductive path of GO in the matrix, because oxidation degree of GO could influence the dispersion and electrical properties. The corrosion protection efficiency of AR/GO(GO: 120 μm, 1.5 wt%, sp2/sp3 = 2.61) is 98.14%, which is 2.26 times higher than AR. The multiscale effects of GO on the corrosion resistance property of AR coatings are quite general, thus providing guidelines for developing highly efficient corrosion resistant coatings for practical usage.

In this study, Sr-incorporated nano-assembled hydroxyapatite structures (HASr) on 316L stainless steel bone plates were prepared by a biomimetic method induced by 10× simulated body fluid (SBF). First, HASr was coated on bone plates by the interaction of ions with 10× SBF containing different concentration of strontium ions. Then, silver coating is achieved as a second layer on bone plates. The cumulative release of strontium ions (Sr2+) and silver ions (Ag+) from multilayered HASr-Ag bone plates at the end of 15 days was in the range of 0.016–0.085 mM and 0.064–0.135 mM, respectively. The release mechanism for the bone plates was evaluated by several mathematical models that best fit the release data. The results showed that Sr2+ and Ag+ are released from multilayered bone plates by diffusion, whereas the release of Ag+ is not occurred by diffusion, instead the mechanism is dissolution, when silver is coated alone on bone plates.

The objective of this study was to understand the effects of ceramic polymer composite and pH of the surrounding vicinity on the release kinetics of doxorubicin. Different concentrations of polymers with polycaprolactone (PCL), poly glycolic lactic acid (PLGA), and a blend of PCL–PLGA with hydroxyapatite (HA) were investigated for doxorubicin release at physiological pH of 7.4 and an acidic pH of 5.0 caused by immediate surgery. Burst release of 20% was observed from bare HA at pH 7.4 over a week, whereas all the polymer incorporated discs showed sustained release. The hydrophilic–hydrophobic and hydrophobic–hydrophobic interactions between the polymer and the drug altered by the surrounding pHs were found to be pivotal in controlling the release kinetics of drug. No cytotoxicity of the drug at a concentration of 50 μg per disc was observed at early time points when cultured with osteoblast cells; however, the same drug dosage inhibited osteosarcoma cell viability. This study mainly bases on the comprehension of the effects of chemistry, environment, and polymer–drug interactions, leading to a beneficial understanding towards the design of drug delivery devices.