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Despite the development of numerous coating techniques and materials, today’s anti-biofouling applications require coatings that are facile and mechanically robust in nature. Studies on the hydrophobicity of rare-earth oxides have risen due to their unusual chemical properties; ytterbium oxide is one such oxide substance. In this study, spray combustion was used to create a hydrophobic coating of ytterbium oxide (Yb2O3) on a stainless steel (SS) substrate, which was then vacuum-treated. GI-XRD analysis confirmed the sesquioxide cubic crystalline structure of Yb2O3. FESEM images displayed an underneath wavy morphological coating with discrete particles on the surface. The thickness and roughness were ~12 and ~0.17 µm, respectively. When 5 and 10 N loads were applied, the coating showed better scratch hardness than uncoated SS. Water contact angle (WCA) <10° indicated superhydrophilicity in the fabricated coating. After vacuum treatment, it became hydrophobic, and the WCA was 128°; because of the increment in the relative area fraction of the C–H bond. The proportion of area covered by blue–green algae (Phormidium sp.) on vacuum-treated Yb2O3 coating was only 3% compared to uncoated SS samples, 80%. [ABSTRACT FROM AUTHOR]

Semiparametric models hold promise to address many challenges to statistical inference that arise from real‐world applications, but their novelty and theoretical complexity create challenges for estimation. Taking advantage of the broad applicability of semiparametric models, we propose some novel and improved methods to estimate the regression coefficients of generalized partially linear models (GPLM). This model extends the generalized linear model by adding a nonparametric component. Like in parametric models, variable selection is important in the GPLM to single out the inactive covariates for the response. Instead of deleting inactive covariates, our approach uses them as auxiliary information in the estimation procedure. We then define two models, one that includes all the covariates and another that includes the active covariates only. We then combine these two model estimators optimally to form the pretest and shrinkage estimators. Asymptotic properties are studied to derive the asymptotic biases and risks of the proposed estimators. We show that if the shrinkage dimension exceeds two, the asymptotic risks of the shrinkage estimators are strictly less than those of the full model estimators. Extensive Monte Carlo simulation studies are conducted to examine the finite‐sample performance of the proposed estimation methods. We then apply our proposed methods to two real data sets. Our simulation and real data results show that the proposed estimators perform with higher accuracy and lower variability in the estimation of regression parameters for GPLM compared with competing estimation methods. [ABSTRACT FROM AUTHOR]

Stainless steel (SS) is a well-known engineering material which is predominantly used in multitudinous applications; however, the disquieting entity is its deteriorative nature triggered by the corrosion in biological, chemical, and high-temperature surroundings. Zirconia is a noteworthy material because of its remarkable mechanical, thermal, and biocompatible properties. To further improve the properties, the high-temperature phases of zirconia are stabilized at room temperature. Zirconia and its stabilized derivates are favored candidates as protective coatings for SS. They offer high resistance, allow them to perform in corrosive, sensitive environments, and augment the longevity, serviceability of SS. Deposition of zirconia/stabilized-zirconia (Z/s-Z) coatings is accomplished using vapor-phase methods, which are capital-intensive; they comprise high vacuum and processing time, confined space, and more energy consumption, resulting in fabrication cost maximization. Alternatively, solution-phase deposition methods are advantageous, effortless, and capable of depositing on large-area substrates, promising to lessen fabrication costs and to enhance yield. Solution-phase methods, namely dip, spray, and spin coatings, have been investigated to produce effective, high-grade Z/s-Z coatings on SS. This review summarizes the utilized precursors, solvents, and process parameters for depositing Z/s-Z coatings on different types and grades of steel through mentioned solution-phase methods, respectively. The review emphasizes the researched potential applications of solution-phase processed Z/s-Z with a particular role as a protective coating on SS-based implants, surgical instruments preserving corrosion resistance, nontoxicity and biocompatibility in the body fluids. The review also highlights the defensive property of solution-phase processed Z/s-Z coatings to the underneath SS against corrosive chemical media (acids like H2SO4, HCl, HNO3; chlorides like NaCl and toxic gases like H2S, coal). The oxidation protection to the beneath SS by the mentioned coatings in aggressive high-temperature surroundings is also focused in the present review. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA, Ca10(PO4)6(OH)2)-based porous scaffolds have been widely investigated in the last three decades. HA, with excellent biocompatibility and osteoconductivity, has made this material widely used in bone tissue engineering. To improve the mechano-biological properties of HA, the addition of clay to develop HA-based composite scaffolds has gained considerable interest from researchers. In this study, a cost-effective method to prepare a HA–clay composite was demonstrated via the mechanical mixing method, wherein kaolin was used because of its biocompatibility. Prawn (Fenneropenaeus indicus) exoskeleton biowaste was utilized as a raw source to synthesize pure HA using wet chemical synthesis. HA–clay composites were prepared by reinforcing HA with 10, 20, and 30 wt.% of kaolin via the mechanical mixing method. A series of characterization tools such as XRD, FTIR, Raman, and FESEM analysis confirmed the phases and characteristic structural and vibrations bonds along with the morphology of sintered bare HA, HA–kaolin clay composite, and kaolin alone, respectively. The HA–clay composite pellets, uniaxially pressed and sintered at 1100 °C for 2 h, were subjected to a compression test, and an enhancement in mechanical and physical properties, with the highest compressive strength of 35 MPa and a retained open porosity of 33%, was achieved in the HA–kaolin (20 wt.%) clay composite, in comparison with bare HA. The addition of 20% kaolin to HA enhanced its compressive strength by 33.7% and increased its open porosity by 19% when compared with bare HA. The reinforcement of HA with different amounts (10, 20, 30 wt.%) of kaolin could open up a new direction of preparing biocomposite scaffolds with enhanced mechanical properties, improved wear, and better cell proliferation in the field of bone tissue engineering. [ABSTRACT FROM AUTHOR]

The current work delivers room-temperature ammonia (NH3) gas-detectable pristine, Nb-doped TiO2 air- and vacuum-annealed films obtained through the solution-combustion process. Polycrystalline anatase crystal structured films without any dopant oxide phases were processed at 400°C on glass substrates. The crystallinity was higher in pristine films than in doped films; the morphological features were similar in all the films. The films were > 50% transparent, and the estimated optical energy band gap was greater in doped films than in pristine films. All the films detected NH3 gas (25 ppm to 100 ppm) at room temperature, and the gas response was highly dependent on the crystallinity and relative area fraction of adsorbed oxygen (% of OA). The vacuum-annealed pristine film exhibited a better gas response than the other films at all NH3 gas concentrations due to high crystallinity and % of OA (10.15%). The film demonstrated maximum gas response of ~16 towards 100 ppm of NH3 gas and displayed good selectivity. Even though the doping reduced the crystallite size from ~17 nm to ~9 nm, it also diminished the crystallinity of the films, which significantly impacted the deterioration of their gas response. [ABSTRACT FROM AUTHOR]

Over the last few years, high-entropy oxides (HEOs) are subjected to considerable scientific scrutiny due to their exceptional characteristics, tunable properties displaying remarkable performance including colossal dielectric constant, low electrical and thermal conductivity, high-temperature phase stability, excellent magnetic, structural optical properties and extraordinary catalytic behavior. The single-phase crystal structure of multicomponent oxides is stabilized via configurational entropy (Sconfig). An incrementation in the number of elements magnifies Sconfig which dominates the free energy landscape, overcomes enthalpy in Gibb's free energy, and reaches a maximum magnitude while entire elements are in equiatomic fractions. Therefore, accurate control of configurational entropy is the main motive force used to achieve phase pure HEOs by the incorporation of more than four cations in the system in equiatomic proportions with random distributions. HEOs are becoming hotcakes in the field of research as it emphasizes on compositions proximally near the centers of the multicomponent phase diagram, where unexpected behaviors can be anticipated. Thus, presenting a crucial research frontier for the material scientists to explore. As the novel design approach of entropy stabilization is still immature, these new oxide candidates can be engineered for practical applications in batteries, capacitors, nuclear reactors, and thermal barrier coatings. This review addresses the properties like electrochemical, electrical, magnetic, mechanical, catalytic, thermal, etc., of HEOs to date, with additionally focusing on their classification, theoretical predictions, and fundamental understanding of entropy engineering including entropy dominated phase stabilization effect. [ABSTRACT FROM AUTHOR]