Coatings, Volume 11, Issue 5 (May 2021) – 127 articles

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing. Full article

Thick NiTi shape memory alloy coatings (300–500 µm) were produced on graphite and AISI 304 substrates by radio frequency inductively-coupled plasma spray technology (RF-ICP) from feedstock NiTi powders. Their microstructure as well as chemical and phase composition were characterized and a methodology for the characterization of functional shape memory properties of the thick coatings was developed. The coatings exhibited cubic to monoclinic martensitic transformation and shape memory effect. The presented results prove that NiTi coatings with functional thermomechanical properties can be easily produced on structural materials by RF-ICP. Further optimization will be needed to prepare NiTi coatings with better microstructural and chemical homogeneity. Full article

The paper presents study results focused on the microstructural, mechanical, and physicochemical properties of B-Cr coatings obtained by means of modification of diffusion borochromized layers by diode laser beam. The studies were conducted on 145Cr6 tool steel. Diffusion borochromized layers were produced at 950 °C in powder mixture containing boron carbides as a source of boron and ferrochrome as a source of chromium. In the next step these layers were remelted using laser beam. Powers: 600, 900, and 1200 W were used during these processes. The microstructure, microhardness, chemical composition, as well as wear and corrosion resistance of newly-formed B-Cr coatings were determined. As a result of laser beam interaction, the diffusion borochromized layer was mixed with the steel substrate. The study showed that too low laser beam power causes cracks in the newly formed B-Cr coating, and on the other hand, too higher laser beam power causes deep remelting resulting in the loss of microhardness. The reduced corrosion resistance in comparison with diffusion borochromized layers was caused by occurrence cracks or deep remelting. For B-Cr coatings produced using laser beam power 600 W, a small decrease in wear resistance was observed, but note that this coating was much thicker than diffusion borochromized layers. On the other hand, laser beam power of 1200 W caused a significant decrease in wear resistance. Newly formed B-Cr coatings had an advantageous microhardness gradient between the layer and the substrate. Full article

Analog computing from recycling principle for next circular economy scenario has been studied with an iron oxide-coupled graphite/Fe–Si steel structure which was built using recycled waste materials, such as lead pencil and 3% Si steel (Fe–Si steel) foils. Proximity phenomena, such as disordered structure of iron oxide and magnetostriction-induced conduction, inside graphite lattice resulted in functional properties to advance analog architectures. Thermal oxidation was the synthesis route to produce iron oxide as coating film on Fe–Si steel foil, whose structure properties were validated by Raman spectroscopy where phase formation of hematite, α-Fe₂O₃, resulted as iron oxide thin-film. Three graphite layers with different compositions were also analyzed by Raman spectroscopy and used for studying electrical conduction in Fe–Si steel/α-Fe₂O₃/graphite structure from current–voltage plots at room temperature. Full article

The electrical resistance and polarization effect of cement paste containing reinforcement were tested to research the anti-corrosion properties of steel bars in cement paste. Moreover, the microstructure and composition of passivation film and rust on the steel bars were studied. The water–cement ratio of the cement paste in this study was 0.3, with 0.5% NaCl, 1% NaNO₂, and 1% Benzotriazole, and an assembly unit of 0.5% NaNO₂ + 0.5% Benzotriazole by mass of cement was added to the cement to provide a chloride environment. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were applied to research the composition of the passivation film and the microstructure of the cement paste, respectively. The results indicated that the samples with the assembly unit of 0.5% NaNO₂ + 0.5% Benzotriazole showed the highest electrical resistance and polarization electrical resistance, while the specimens with 1.0% Benzotriazole showed the lowest electrical resistance and polarization electrical resistance. Moreover, the passivation film of steel bars weakened with increasing distance from the surface of the steel bars. Therefore, the corrosion of steel bars becomes more serious with increasing distance. Finally, the influence of the rust inhibitor on the corrosion resistance of steel bars in the specimens decreased in the following order: 0.5% NaNO₂ + 0.5% Benzotriazole >1.0% NaNO₂>1.0% Benzotriazole. Full article

The objective of the present work was to evaluate novel active films made with biopolymeric matrices as carriers of a living Bdellovibrio bacteriovorus HD100 strain, a predatory bacterium with antimicrobial potentials against pathogens. Biopolymer films were prepared by a casting method using the following mixtures: collagen/sodium alginate/sorbitol (CA-S), collagen/sodium alginate/glycerol (CA-G), and tapioca starch/sodium alginate/glycerol (StA-G). The effects of the film formulations on the viability of the B. bacteriovorus was investigated by using Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). SEM showed that Bdellovibrio bacteriovorus morphology was not altered in the polymeric films. FTIR spectroscopy provided information about the structural composition of the films. CA-S showed less reduction in the viability of B. bacteriovorus after its entrapment; thus, CA-S proved to be a better agent for the immobilization and preservation of B. bacteriovorus to enhance its predatory activities during application against Escherichia coli. Full article

Active films based on carboxymethyl chitosan incorporated corn peptide were developed, and the effect of the concentration of corn peptide on films was evaluated. Physicochemical properties of the films, including thickness, opacity, moisture content, color, mechanical properties, water vapor permeability, and oil resistance, were measured. Biological activities of the films, including the antioxidant and antibacterial activities, were characterized in terms of 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging activity, reducing power, the total antioxidant activity, and the filter disc inhibition zone method. The results indicated that the incorporation of corn peptide caused interactions between carboxymethyl chitosan and corn peptide in Maillard reaction and gave rise to the films light yellow appearance. Compared with the Control, the degree of glycosylation, browning intensity, thickness, opacity, tensile strength, antioxidant activity, and antibacterial activity of films were increased, but the elongation, vapor permeability, and oil resistance of films were decreased. The films based on corn peptide and carboxymethyl chitosan can potentially be applied to food packaging. Full article

The purpose of this study is to improve the mechanical durability and surface frictional characteristics of polymer/ceramic-based composite materials. Polydimethylsiloxane (PDMS)/glass bubble (GB) composite specimens are prepared at various weight ratios (PDMS:GB) by varying the amount of micro-sized GBs added to the PDMS. The surface, mechanical, and tribological characteristics of the PDMS/GB composites are evaluated according to the added ratios of GBs. The changes in internal stress according to the indentation depth after contacting with a steel ball tip to the bare PDMS and PDMS/GB composites having different GB densities are compared through finite element analysis simulation. The elastic modulus is proportional to the GB content, while the friction coefficient generally decreases as the GB content increases. A smaller amount of GB in the PDMS/GB composite results in more surface damage than the bare PDMS, but a significant reduction in wear rate is achieved when the ratio of PDMS:GB is greater than 100:5. Full article

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10⁻¹¹ g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications. Full article

The application of fused filament fabrication processes is rapidly expanding in many domains such as aerospace, automotive, medical, and energy, mainly due to the flexibility of manufacturing structures with complex geometries in a short time. To improve the mechanical properties of lightweight sandwich structures, the polymer matrix can be strengthened with different materials, such as carbon fibers and glass fibers. In this study, fiber-reinforced composite sandwich structures were fabricated by FFF process and their mechanical properties were characterized. In order to conduct the mechanical tests for three-point bending, tensile strength, and impact behavior, two types of skins were produced from chopped carbon-fiber-reinforced skin using a core reinforced with chopped glass fiber at three infill densities of 100%, 60%, and 20%. Using microscopic analysis, the behavior of the breaking surfaces and the most common defects on fiber-reinforced composite sandwich structures were analyzed. The results of the mechanical tests indicated a significant influence of the filling density in the case of the three-point bending and impact tests. In contrast, the filling density does not decisively influence the structural performance of tensile tests of the fiber-reinforced composite sandwich structures. Composite sandwich structures, manufactured by fused filament fabrication process, were analyzed in terms of strength-to-mass ratio. Finite element analysis of the composite sandwich structures was performed to analyze the bending and tensile behavior. Full article

The thermal insulation properties of thermal barrier coatings (TBCs) can be significantly improved with increasing the coating thickness. However, due to the weak bonding of high-thickness TBCs, the low reliability and short lifetime greatly limits their application under some severe operating conditions. In this study, a novel and high-efficiency synchronous dual powder feeding method is used to deposit a series of gradient NiCoCrAlY/YSZ coatings with millimeter level thickness. The tensile bonding strengths and residual stress state of coatings are evaluated in order to explore the effect of thickness on the bonding strength of coatings. The results suggested that, due to some micro-convex structure at the “GC/TC” interface and inside “GC” layer, the bonding strength of 1000-μm-thickness gradient NiCoCrAlY/YSZ TBCs with the 4:6 and 2:8 hybrid ratios is over 44 MPa compared to the common TBCs. The fracture position gradually shifts from NiCoCrAlY bond coat to NiCoCrAlY/YSZ transition zone and finally to the YSZ top coat owing to the different position of residual stress concentrations. After thermal cycling tests, the 1000-μm-thickness gradient coating exhibits a higher thermal cycling life. Some coarse cracks initiate and propagate at the bottom region of TBCs, which is mainly due to thermal expansion mismatch stress that finally results in the failure of the gradient coating between the “BC” layer and the substrate. Full article

The laterally graded multilayer collimator is a vital part of a high-precision diffractometer. It is applied as condensing reflectors to convert divergent X-rays from laboratory X-ray sources into a parallel beam. The thickness of the multilayer film varies with the angle of incidence to guarantee every position on the mirror satisfies the Bragg reflection. In principle, the accuracy of the parameters of the sputtering conditions is essential for achieving a reliable result. In this paper, we proposed a precise method for the fabrication of the laterally graded multilayer based on a planetary motion magnetron sputtering system for film thickness control. This method uses the fast and slow particle model to obtain the particle transport process, and then combines it with the planetary motion magnetron sputtering system to establish the film thickness distribution model. Moreover, the parameters of the sputtering conditions in the model are derived from experimental inversion to improve accuracy. The revolution and rotation of the substrate holder during the final deposition process are achieved by the speed curve calculated according to the model. Measurement results from the X-ray reflection test (XRR) show that the thickness error of the laterally graded multilayer film, coated on a parabolic cylinder Si substrate, is less than 1%, demonstrating the effectiveness of the optimized method for obtaining accurate film thickness distribution. Full article

Pure and Mg-doped manganese oxide thin films were synthesized on heated glass substrates using the spray pyrolysis technique. The surface chemical composition was investigated by the use of X-ray photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). Optical properties were characterized by UV-visible spectroscopy. XPS spectra showed typical Mn (2p3/2), (2p1/2) and O (1s) peaks of Mn₃O₄ with a slight shift attributed to the formation of different chemical states of manganese. XRD analysis revealed the tetragonal phase of Mn₃O₄ with a preferred (211) growth orientation that improved with Mg-doping; likewise, grain size is observed to increase with the Mg doping. SEM images of Mn₃O₄ films showed rough surfaces composed of uniformly distributed nanograins whose size decreases with the Mg-doping. The manganese oxide films surface observed in AFM show a textured, rough and porous surface. The combination of transmittance and absorption data in the UV-visible range allowed determining the energy values of the Eg band gap (1.5–2.5 eV). The decrease of the band gap with the Mg-doping increase is attributed to the influence of the greater size of the Mg²⁺ ion in the manganese oxide lattice. Full article

Ti-23Nb (at.%) coatings on an NiTi alloy with metallurgical bonding were prepared by laser cladding (LC) technology using Ti-Nb mixture powders. The effects of laser processing parameters on the microstructure and mechanical properties of the coatings were systematically investigated and the corrosion resistance of the coatings was assessed. The coatings were composed of TiNb, (Ti, Nb)₂Ni, and β-Nb phases. The coatings increased the hardness of the NiTi alloy by a combined strengthening effect of the eutectics and fine microstructure. The corrosion resistance of the coated part was improved. The coatings with great corrosion resistance could keep the coated parts inert in an aggressive environment, and effectively restrain the release of toxic Ni ions, which means that the Ti-Nb alloy coatings are likely to be used as a biomaterial for medical applications. Full article

Nitrite is widespread in the environment, and is frequently used as an additive to extend the shelf life of meat products. However, the excess intake of nitrite can be harmful to human health. Hence, it is very important to know and control the content of nitrite in foodstuffs. In this work, by the means of self-assembly induced by solvent evaporation, we used the amphiphilic PEO-b-PS diblock copolymers resol and cobalt nitrate as a template to synthesize ordered mesoporous CoO_x/C nanocomposites. Then, the CoO_x/C nanocomposites were modified on a glassy carbon electrode (GCE), which showed excellent sensitivity, good selectivity, and a wide detection range for nitrite. Through cyclic voltammetry and current–time techniques, the electrochemical performance of the GCE modified with CoO_x/C nanocomposites was analyzed. Under the optimized conditions, we found that anodic currents were linearly related to nitrite concentrations with a regression equation of lp (µA) = 0.36388 + 0.01616C (R² = 0.9987) from 0.2 µM to 2500 µM, and the detection limit was 0.05 µM. Furthermore, the electrochemical sensor behaved with high reproducibility and anti-interference ability towards various organic and inorganic ions, such as NO₃⁻, SO₄²⁻, Cl⁻, COOH⁻ (Ac⁻), Na⁺, K⁺, Mg²⁺, and NH⁴⁺. Our results indicated that these CoO_x/C nanocomposites could be applied in electrochemical sensors for the rapid and sensitive detection of the food preservative nitrite. Full article

Silicon photonic devices with either silicon or silicon nitride waveguides have increasingly been used in many applications besides communications, especially as sensors in label-free biosensing, where guided light signals are affected by biorecognition molecules immobilized on the surface. The coating of protein (i.e., bioreceptors) by biochemical process on the waveguide surface is a crucial step in creating a functionalized device that can be used for biosensing. As a conventional method that uses 3-aminopropryltriethoxysilane (APTES) and glutaraldehyde (GA), the APTES-GA method has the limitation of using a GA crosslink, of which the two functional groups can bind to nonspecific proteins, causing irregular binding. In this study, we proposed a new coating technique to avoid such problem by applying APTES silanization with 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide (EDC)-N-hydroxysuccinimide (NHS) protein crosslink, denoted by the APTES-(EDC/NHS) method. The EDC/NHS reaction was shown to be able to immobilize protein in ordered orientation due to consistent arrangement between a carboxylic group of protein molecules and an amine group of covalent-linked APTES on surface. By applying APTES silanization, we circumvented the use of hazardous cleaning agent in the conventional EDC/NHS technique. Several surface characterization techniques were carried out to assess and compare the two biocoating techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), spectroscopic ellipsometry (SE), and atomic force microscopy (AFM). On silicon, the results of antihuman TNF-alpha antibody coating showed that the proposed APTES-(EDC/NHS) technique has better repeatability in terms of less roughness of the coated protein at 1.5 nm compared with 6.3 nm, due to the ordered arrangement of coated antibody molecules. On a silicon nitride waveguide device, the proposed APTES-(EDC/NHS) technique exhibits dense antibody immobilization on a waveguide in SEM images due to stable amide bond formation via EDC/NHS crosslink mechanism. The specificity of the immobilized antibodies was confirmed by enzyme-linked immunosorbent assays (ELISA), with an average optical density at 450 nm of 0.175 ± 0.01 compared with 0.064 ± 0.009 of negative control. The proposed technique also reduced the overall process time since proteins are crosslinked to the silanized waveguide surface in a single step. Full article

Cadmium (Cd) is widely used in some industries and emitted from fossil fuels. It is a heavy metal with a number of side effects, including hepatotoxicity. Resveratrol (Rs) is considered an important polyphenol, which is a secondary plant metabolite and has the ability to scavenge free radicals. The study was designed to evaluate the effects of resveratrol on Cd, which induced hepatotoxicity, by the assessment of some histopathological and biochemical alterations. Forty male albino rats were divided into four groups: the 1st group was the control group, the 2nd group was treated with Cd (5 mg/kg), the 3rd group was given Rs (20 mg/kg), and the 4th group was treated with Cd in combination with Rs intraperitoneally for 30 successive days. The results indicate that Cd increased liver enzymes alanine aminotransferase and aspartate aminotransferase (AST and ALT), alkaline phosphatase ALP and gamma-glutamyl transferase (γ-GT) while reducing the total protein level; Cd increased the malondialdhyde (MDA) level while decreasing the levels of other antioxidant enzymes super oxide dismutase, catalase and glutathione peroxidase (SOD, CAT and GPx). Serious congestion and hemorrhage related to the hepatic tissues were noticed in the Cd group, and Rs plays a major role in alleviating histopathological injuries and hepatic oxidative damage. It is clear that Rs has the ability to minimize the hepatotoxicity induced by Cd in male rats. Full article

This study reports the recovery of Pd(II) from acid solution by a polyethylenimine (PEI)-crosslinked chitin (PEI-chitin) biosorbent. FE-SEM analysis demonstrated that there are many slot-like pores on PEI-chitin. The N₂ adsorption–desorption experiment revealed that the average pore size was 47.12 nm. Elemental analysis verified the successful crosslinking of PEI with raw chitin. The Langmuir model better explained the isotherm experimental data and the theoretical maximum Pd(II) uptake was 57.1 mg/g. The adsorption kinetic data were better described by the pseudo-second-order model and the adsorption equilibrium was achieved within 30 min for all initial Pd(II) concentrations of 50–200 mg/L. In the fixed-bed column, the adsorption of Pd(II) on PEI-chitin showed a slow breakthrough and a fast saturation performance. The desorption experiments achieved a concentration factor of 8.4 ± 0.4; in addition, the adsorption–desorption cycles in the fixed-bed column were performed up to three times, consequently confirming the good reusability of PEI-chitin for Pd(II) recovery. Therefore, the PEI-chitin can be used as a promising biosorbent for the recovery of Pd(II) in practical applications. Full article

This article is aimed to study the effect of laser treatment of AISI 304 stainless steel on the corrosion resistance and chemical composition of the surface layer. The samples were irradiated using two quite different laser sources: IPG Yb:glass fibre laser (τ = 230 ns, λ = 1062 nm) and Trumpf TruMicro Series 2020 fiber laser (τ = 260 fs–20 ps, λ = 1030 nm) that is, in both the long and ultra-short pulse duration regime. It allowed the observation of completely different microstructures and chemical composition of the surface layer. In this study, the morphology of the samples was accessed using both Keyence digital microscope and Olympus Lext 5000 profilometer. The corrosion resistance was examined in 3% NaCl solution using both potentiodynamic measurement and Electrochemical Impedance Spectroscopy. In order to examine the change in chemical composition of the surface layer, the X-ray photoelectron spectroscopy study was performed. Results show that the use of a long laser pulse contributes to the formation of a thin, tight, rich in chromium passive layer, which significantly improves corrosion resistance in comparison to the reference sample. Different behaviour is observed after irradiation with an ultra-short pulse duration laser. Full article

The electron transport layer (ETL) is critical to carrier extraction for perovskite solar cells (PSCs). Moreover, the morphology and surface condition of the ETL could influence the topography of the perovskite layer. ZnO, TiO₂, and SnO₂ were widely investigated as ETL materials. However, TiO₂ requires a sintering process under high temperature and ZnO has the trouble of chemical instability. SnO₂ possesses the advantages of low-temperature fabrication and high conductivity, which is critical to the performance of PSCs prepared under low temperature. Here, we optimized the morphology and property of SnO₂ by modulating the concentration of a SnO₂ colloidal dispersion solution. When adjusting the concentration of SnO₂ colloidal dispersion solution to 5 wt.% (in water), SnO₂ film indicated better performance and the perovskite film has a large grain size and smooth surface. Based on high efficiency (16.82%), the device keeps a low hysteresis index (0.23). Full article

To obtain high-quality n-type doped β-Ga₂O₃ films, silane was used as an n-type dopant to grow Si-doped β-Ga₂O₃ films on (100) β-Ga₂O₃ substrates by metal-organic chemical vapor deposition (MOCVD). The electron concentrations of the Si-doped β-Ga₂O₃ films obtained through experiments can be stably controlled in the range of 6.5 × 10¹⁶ cm⁻³ to 2.6 × 10¹⁹ cm⁻³, and the ionization energy of Si donors is about 30 meV, as determined by analysis and calculation. The full width at half maxima of the rocking curves of the (400) crystal plane of all doped films was less than 500 arcsec, thus showing high crystal quality, while the increase of the doping concentration increased the defect density in the β-Ga₂O₃ films, which had an adverse effect on the crystal quality and surface morphology of the films. Compared with heteroepitaxial Si-doped β-Ga₂O₃ films, homoepitaxial Si-doped β-Ga₂O₃ films exhibited higher quality, lower defect density, and more stable electron concentration, which make them more conductive for preparing Ga₂O₃-based power devices. Full article

Pure In₂O₃ and 6% Cr-doped In₂O₃ thin films were prepared on a silicon (Si) substrate by pulsed laser deposition technique. The obtained In₂O₃/In₂O₃:Cr thin films structural, morphological, optical, magnetic and gas sensing properties were briefly investigated. The X-ray diffraction results confirmed that the grown thin films are in single-phase cubic bixbyte structure with space group Ia-3. The SEM analysis showed the formation of agglomerated spherical shape morphology with the decreased average grain size for Cr doped In₂O₃ thin film compared to pure In₂O₃ film. It is observed that the Cr doped In₂O₃ thin film shows the lower band gap energy and that the corresponding transmittance is around 80%. The X-ray photoelectron spectroscopy measurements revealed that the presence of oxygen vacancy in the doped In₂O₃ film. These oxygen defects could play a significant role to enhance the sensing performance towards chemical species. In the magnetic hysteresis loop, it is clear that the prepared films confirm the ferromagnetic behaviour and the maximum saturation value of 39 emu/cc for Cr doped In₂O₃ film. NH₃ gas sensing studies was also carried out at room temperature for both pure and Cr doped In₂O₃ films, and the obtained higher sensitivity is 182% for Cr doped In₂O_3, which is about nine times higher than for the pure In₂O₃ film due to the presence of defects on the doped film surface. Full article

Polysaccharides have excellent potential as food-grade coating materials for microencapsulation in pro- and prebiotics-based functional food industry. In this study, potato, maize, and rice resistant starches composite coatings with D-mannose, maltodextrin, and whey protein concentrate were prepared for the spray-dried microencapsulation of Lactobacillus acidophilus KLDS 1.1003. Assessment of different polysaccharide coatings to enhance the longevity of probiotics at high temperatures of spray-drying process, storage, and targeted delivery in the gastrointestinal tract were the key objectives of the present study. The highest microencapsulation efficiencies were shown by maize (95.80%) and potato (94.30%) resistant starches. Similarly, maize resistant starch (MRS)-based composites provided the highest thermal resistance, with Tg 38.77 ± 1.10–93.13 ± 0.81 °C and showed the least 2.1 log cycles viability loss in simulated GI tract. Viability losses during storage were in the following order: control > RRS > PRS > MRS, and the inactivation rate of the microencapsulated cells followed the first-order kinetics (R² = 0.9264–0.9918). The resistant starch-based spray-dried microcapsules possessed 27.00 ± 0.03 to 52.28 ± 1.02 µm size range and SEM micrographs showed a unified smooth surface without cracks and ruptures. These findings will expand the potential use of natural food-grade coatings in functional foods and allied industries involving spray-dried products. Full article

This work deals with the interfacial mixing mechanism of picoliter (pL)-scale droplets produced by sequential inkjet printing of organic-based inks onto ITO/PET surfaces at a moderately high Weber number (~10¹). Differently from solution dispensing processes at a high Bond number such as spin coating, the deposition by inkjet printing is strictly controlled by droplet velocity, ink viscosity, and surface tension. In particular, this study considers the interfacial mixing of droplets containing the most investigated donor/acceptor couple for organic solar cells, i.e., poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl-C₆₁-butyric acid methyl ester (PCBM), showing how low-viscosity and low-surface energy inks can be leveraged for the fabrication of an interface suitable for a pseudo-planar heterojunction (pseudo-PHJ) organic solar cell (OSC) that is a convenient alternative to a bulk heterojunction (BHJ) OSC. The resulting thin-film morphology and molecular organization at the P3HT/PCBM interface are investigated, highlighting the roles of dissolution-driven molecular recirculation. This report represents a first step toward the sequential inkjet printing fabrication of pseudo-PHJ OSCs at low consumption of solvents/chemicals. Full article

The indium-free amorphous oxide semiconductor thin film transistor (AOS-TFT) with aluminum (Al) electrodes shows broad application prospects in new-generation display technologies, such as ultra-high definition large-screen display, OLED display and 3D display. In this work, the thin film transistor (TFT) with a zinc-aluminum-tin-oxide (ZATO) semiconductor as the active layer and an Al electrodes as the source and drain (S/D) was investigated. The optical, electrical and semiconductive properties of the ZATO films were evaluated by atomic force microscopy (AFM), ultraviolet–visible spectrophotometry and microwave photoconductivity decay (μ-PCD), respectively. The result shows that the film is smooth and transparent and has low localized states and defects at a moderate oxygen concentration (~5%) and a low sputtering gas pressure (~3 mTorr). After the analysis of the transfer and output characteristics, it can be concluded that the device exhibits an optimal performance at the 623 K annealing temperature with an I_on/I_off ratio of 5.5 × 10⁷, an SS value of 0.15 V/decade and a saturation mobility (μ_sat) of 3.73 cm²·V⁻¹·s⁻¹. The ZATO TFT at the 623 K annealing has a −8.01 V negative shift under the −20 V NBS and a 2.66 V positive shift under the 20 V PBS. Full article

Ultra-high molecular weight polythene (UHMWPE), with outstanding characteristics, is widely applied in modern industry, while it is also severely limited by its inherent shortcomings, which include low hardness, poor wear resistance, and easy wear. Implementation of feasible protection on ultra-high molecular weight polythene to overcome its shortcomings would be of significance. In the present study, amorphous carbon (a-C) film was fabricated on ultra-high molecular weight polythene (UHMWPE) to provide good protection, and the relevant growth mechanism of a-C film was revealed by controlling carbon plasma currents. The results showed the in situ transition layer, in the form of chemical bonds, was formed between the UHMWPE substrate and the a-C film with the introduction of carbon plasma, which provided strong adhesion, and then the a-C film continued epitaxial growth on the in situ transition layer with the treatment of carbon plasma. This in situ growth of a-C film, including the in situ transition layer and the epitaxial growth layer, significantly improved the wetting properties, mechanical properties, and tribological properties of UHMWPE. In particular, good protection by in situ growth a-C film on UHMWPE was achieved during sliding wear. Full article

In this study, a new coating material for thermal barrier coating (TBC) or environment barrier coating (EBC) application, Ca₃ZrSi₂O₉ (CZSO), was synthesized and prepared by atmospheric plasma spray (APS) technology. The evolution of the phases and microstructures of the coatings with different thermal-aged were characterized by XRD, XRF, EDS and SEM, respectively. The thermal stability was measured by TG-DTA and DSC. The mechanical and thermal properties, including Vickers hardness (H_V), fracture toughness (K_IC), thermal conductivity (κ) and coefficient of thermal expansion (CTE) were focused on. It was found that the as-sprayed CZSO coating contained amorphous phase. Crystalline transformation happened at 900–960 °C and no mass changes took place from room temperature (RT) to 1300 °C. The phenomena of microcrack self-healing and composition uniformity were observed during thermal aging. The κ of coating was very low at about 0.57–0.80 W·m⁻¹·K⁻¹ in 200–1200 °C. The combined properties indicated that the CZSO coating might be a potential T/EBC material. Full article

Modifications of biomaterials based on the combination of physical, chemical, and biological cues for manipulating stem cell growth are needed for modern regenerative medicine. The exploitation of these sophisticated modifications remains a challenge, including substrate limitation, biocompatibility, and versatile and general cues for stem cell activities. In this report, a vapor-phase coating technique based on the functionalization of poly-p-xylylene (PPX) was used to generate a surface modification for use with stem cells in culture. The coating provided the ability for covalent conjugation that immobilized bone morphogenetic protein 2 (BMP-2) and fibroblast growth factor 2 (FGF-2), and the modified coating surfaces enabled direct stem cell differentiation and controlled proliferation because of the specific activities. The ligations were realized between the growth factors and the maleimide-modified surface, and the conjugation reactions proceeded with high specificity and rapid kinetics under mild conditions. The conjugation densities were approximately 140 ng·cm⁻² for BMP-2 and 155 ng·cm⁻² for FGF-2. Guiding the activities of the human adipose-derived stem cells (hADSCs) was achieved by modifying surfaces to promote the hADSC differentiation capacity and proliferation rate. The reported coating system demonstrated biocompatibility, substrate-independent conformity, and stability, and it could provide an effective and versatile interface platform for further use in biomedical applications. Full article