Smooth Surface Research Articles

Structural and optical properties of epitaxial ScxAl1−xN coherently grown on GaN bulk substrates by sputtering method

Three scandium aluminum nitride (ScAlN) thin films with different Sc compositions of 6%, 10%, and 14% were heteroepitaxially grown on n-type GaN bulk substrates by a low-temperature sputtering method. Atomically flat and smooth surfaces were observed by atomic force microscopy. The ScAlN films were coherently grown on GaN, and the c-axis lattice constants increased with increase in the Sc composition, confirmed by x-ray diffraction. The refractive index and the extinction coefficient of ScAlN were extracted by variable angle spectroscopic ellipsometry. The refractive index slightly increased and the extinction coefficient showed red shift with increase in the Sc composition. The optical bandgap of the ScAlN films was also extracted, which slightly shrunk with increase in the Sc composition.

Turbulent Thermal Convection At A Rough Surface

We present measurements of the near-wall velocity field in highly turbulent Rayleigh-Bénard(RB) convection with rough horizontal surfaces. The measurements have been undertaken in a large-scale RB experiment which is called "Barrel of Ilmenau". We used the technique of stereoscopic Particle Image Velocimetry to measure the three components of the velocity field in horizontal planes parallel to the heated bottom plate. The measurements reported here comprise two Rayleigh numbers Ra=8.6×10^{10} and Ra=6.3×10^{11}. The Prandtl number of the working fluid was Pr=0.7. We used a chess board-like pattern of cuboids with a base area of 30 mm by 30 mm and a height of h=12 mm. Our measurements confirm the observation from previous experiments that the relation Nu=f(Ra) remains unchanged with respect to RB convection with smooth surfaces as long as the thickness of the thermal boundary layer \delta_{th}=H/(2Nu) exceeds the height of the roughness elements h. If \delta_{th} falls below h, Nu becomes larger and grows faster with increasing Ra then it does in RB convection with smooth plates. We also could identify the valleys in between the cuboids as the main contribution for the increase of Nu

Dual First and Second Surface Solar Mirrors of Polished WS2 and Silver by Dynamical Chemical Plating Technique on Polycarbonate.

This work proposes for the first time protecting-reflecting on both sides of plated mirrors and a solution to polycarbonate surface vulnerability to weathering and scratching using tungsten disulfide (WS2) by mechanical polishing. The ability of the dynamic chemical plating (DCP) technique to deposit Ag films at the nanometer scale on a polycarbonate (PC) substrate and its characteristics to be metallized is also shown. These deposits hold significant promise for concentrated solar power (CSP) applications. Complementarily, the application of WS2 as a reflective film for CSP by mechanical polishing on smooth polycarbonate surfaces is both novel and practical. This technique is innovative and scalable without needing reactants or electrical potential, making it highly applicable in real-world scenarios, including, potentially, on-site maintenance. The effects of surface morphology and adhesion, and the reflectivity parameters of the silver metallic surfaces were investigated. Wettability was investigated because it is important for polymeric surfaces in the activation and metal deposition immediately after redox reactions. The flame technique improved wettability by modifying the surface with carbonyl and carboxyl functional groups, with PC among the few industrial polymers that resisted such a part of the process. The change in the chemical composition, roughness, and wettability of the surfaces effectively improved the adhesion between the Ag film and the PC substrate. However, it did not significantly affect the adhesion between PC and WS2 and showed its possible implementation as a first surface mirror. Overall, this work provides a scalable, innovative method for improving the durability and reflectivity of polycarbonate-based mirrors, with significant implications for CSP applications.

Enhancing and broadening the photoresponse of CdS nanowire by constructing core–shell heterostructure

Limited by the severe surface recombination and large bandgap, it is still a challenge to achieve a high-performance broad-spectrum photodetector based on CdS nanowires (NWs). In this work, the CdS/GeS core–shell heterostructure is constructed to enhance and broaden the photoresponse of CdS NWs. The CdS/GeS core–shell heterostructure NWs are prepared by the chemical vapor deposition method, exhibiting smooth surfaces, controlled shell thicknesses, and compositions. From the UV-Vis-near-infrared (NIR) diffuse reflectance spectrum, PL, and time-resolved photoluminescence studies, it is found that the surface recombination is weakened and the light absorption range is widened after the constructing core–shell heterostructure. When configured into photodetectors, the responsivity of the CdS/GeS core–shell heterostructure NWs is up to 76.8 A W−1, which is 10 folds higher than that of pristine CdS NWs. Furthermore, the photoresponse wavelength of the CdS/GeS core–shell heterostructure NWs is extended from 405 to 850 nm. The improved photodetection performance is attributed to the effective separation of photogenerated carriers at the heterostructure interface, weakened surface recombination, and excellent light absorption of the GeS shell. All results imply that constructing core–shell heterostructures is an effective strategy for constructing high-performance photodetectors.

Ultra-low stress-hysteresis and huge superelasticity in NiMn-based shape memory microwire

Hysteresis related to first-order phase transformation in shape memory alloys, which is the macroscopic manifestation of energy dissipation, is detrimental to the precise control of actuation and causes structural and functional fatigue of components. It is of vital importance to explore high-performance shape memory alloys with low stress-hysteresis, large superelasticity, and wide temperature range operation in practical applications. Here, we have developed a Ni-Mn-Fe-In shape memory microwire, exhibiting an ultra-low stress-hysteresis and huge tensile superelasticity in a wide temperature range. The microwire shows a smooth surface and a single crystal structure (with ⟨001⟩A-oriented along the axial direction of microwire), and the microstructure of the microwire contains austenite matrix and sparsely distributed precipitates with an average size of 20–80 nm, all of which may be beneficial to obtain low hysteresis and large strains in the microwire. As a result, the microwire exhibits a minimum stress-hysteresis of as low as 8.5 MPa (with overall strain of 15.3%) and corresponding energy dissipation as low as 1.44 MJ/m3. The microwire always shows a low stress-hysteresis (less than 24 MPa) and low energy dissipation (less than 2.86 MJ/m3) above room temperature. The microwire shows a huge superelasticity with recoverable strains higher than 15% in the wide temperature range from 218 to 418 K. Together with the advantages of easy fabrication and no post-processing required, this microwire shows a tremendous potential for cyclic actuators and energy conversion devices under multi-field coupling.

Enhancing and broadening the photoresponse of CdS nanowire by constructing core–shell heterostructure

Limited by the severe surface recombination and large bandgap, it is still a challenge to achieve a high-performance broad-spectrum photodetector based on CdS nanowires (NWs). In this work, the CdS/GeS core–shell heterostructure is constructed to enhance and broaden the photoresponse of CdS NWs. The CdS/GeS core–shell heterostructure NWs are prepared by the chemical vapor deposition method, exhibiting smooth surfaces, controlled shell thicknesses, and compositions. From the UV-Vis-near-infrared (NIR) diffuse reflectance spectrum, PL, and time-resolved photoluminescence studies, it is found that the surface recombination is weakened and the light absorption range is widened after the constructing core–shell heterostructure. When configured into photodetectors, the responsivity of the CdS/GeS core–shell heterostructure NWs is up to 76.8 A W−1, which is 10 folds higher than that of pristine CdS NWs. Furthermore, the photoresponse wavelength of the CdS/GeS core–shell heterostructure NWs is extended from 405 to 850 nm. The improved photodetection performance is attributed to the effective separation of photogenerated carriers at the heterostructure interface, weakened surface recombination, and excellent light absorption of the GeS shell. All results imply that constructing core–shell heterostructures is an effective strategy for constructing high-performance photodetectors.

Hygroscopic Mg-Al LDHs composite microspheres for highly efficient hyperspectral camouflage in the VIS and NIR wavebands.

In order to enhance the hyperspectral camouflage efficacy of stealth coatings against a natural vegetative backdrop, LiCl, known for its significant hygroscopic properties, was incorporated into green Mg-Al layered double hydroxide (Mg-Al LDHs) material. Micron-sized composite microspheres were subsequently synthesized via the spray-drying granulation technique. The structure, morphology, and chemical composition of these microspheres were thoroughly characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, nitrogen adsorption-desorption isotherms, and Fourier-transform infrared spectroscopy. The effect of LiCl content on the moisture absorption capacity and near-infrared reflectance spectra of the microspheres was systematically evaluated. We found that incorporating an optimal amount of LiCl into the internal pores of the Mg-Al LDHs microspheres did not compromise their smooth surface morphology and uniform particulate distribution. Notably, when the LiCl content was 10%, the maximum saturation moisture uptake ratio of the coating increased to 0.75g/g. This hygroscopicity significantly enhanced the absorption and scattering of near-infrared radiation by the coating while concurrently improving its ability to modulate the shape and reflectance of both the visible and near-infrared spectral curves. Spectral congruence between the synthetic coating and natural green foliage was quantified at 97.41%. Moreover, this performance was maintained over 10 cycles of programmed drying and re-humidification, and the coating consistently demonstrated stable hygroscopic properties and sustained over 95% spectral congruence. These optimized artificial coatings were found to effectively confuse hyperspectral classification algorithms, thus blending seamlessly into a natural foliage backdrop. This study provides a new method for regulating VIS and NIR spectral (visible-near infrared spectrum) features, which will be critical for applications in advanced hyperspectral camouflage materials.

Photo-aging of brominated epoxy microplastics in water under simulated solar irradiation.

Microplastics have become an increasingly concerning pollutant in aquatic environments, and photodegradation is their main degradation pathway in water. Gaining insight into the transformation process of microplastics will enhance our understanding of their behavior and destiny in natural environments. This paper studied the aging process of BER microplastics in aquatic environments under simulated sunlight and investigated the changes in the physical and chemical properties of microplastics and the changes in the leachate. During the photodegradation process, BER-MPs underwent extensive oxidation and reduction in particle size, and the originally smooth surface developed numerous voids, accompanied by yellowing. Introduction of O atoms in the molecular chains increased their hydrophilicity, resulting in the polymer chains breaking away from the plastic particles and dissolving in water. Also, once BER was excited by light, environmentally persistent free radicals are produced on its surface. Moreover, the breaking of C-Br bonds occurred during the photodegradation process of BER-MPs, which suggested that tetrabromobisphenol A would be transformed during the photoaging process of BER even if it was covalently bound to BER.

HIGH-FREQUENCY METHODS FOR COMPLEX AIRBORNE RADAR OBJECTS SCATTERING CHARACTERISTICS CALCULATING

The current state of radar to perform detection and recognition tasks development requires knowledge of a priori information about the secondary radiation of radar objects characteristics. Obtaining this information concerning the target is possible by means of physical or mathematical modelling. Information concerning radar objects obtained by conducting field and physical experiments is associated with significant material, organizational and time costs. Therefore, the method of mathematical modelling can be considered as the most affordable way to obtain information on scattering characteristics. This paper evaluates modern high-frequency methods for the scattering characteristics (secondary radiation) calculating on complex airborne radar objects by mathematical modelling. The calculation of the objects scattering characteristics with surface breaks is carried out by preliminary dividing the surface into a smooth part and edge areas of the surface. The corresponding mathematical relations obtained can be used to estimate the secondary radiation of a complex airborne radar object. The article defines the possibilities of modern high-frequency methods for calculating the scattering characteristics of complex airborne radar objects using mathematical modelling, namely: calculation of scattering characteristics by a smooth surface of a complex airborne radar object; calculation of the scattering characteristics by the edge local surface areas with a radio-absorbing coating of a complex airborne radar object. The scattering characteristics of objects with surface breaks are calculated by first dividing the surface into a smooth part and edge areas. To calculate the scattered field, Kirchhoff-type integral representations are used. Thus, the integration surface covering the scattered in these integral representations is chosen to coincide with the object's surface everywhere except for some edge area. The corresponding mathematical relations for scattering characteristics calculating on smooth and edge localized surface areas of a complex airborne radar object are obtained. The presented calculation methods application can contribute to obtaining a priori information (as required by the current state of radar development) concerning the scattering characteristics of complex airborne radar objects, taking into account such complicating factors as the heterogeneity of the boundary surface, the presence of radio-absorbing coatings, and taking into account their complex effect.

Ultra-low stress-hysteresis and huge superelasticity in NiMn-based shape memory microwire

Hysteresis related to first-order phase transformation in shape memory alloys, which is the macroscopic manifestation of energy dissipation, is detrimental to the precise control of actuation and causes structural and functional fatigue of components. It is of vital importance to explore high-performance shape memory alloys with low stress-hysteresis, large superelasticity, and wide temperature range operation in practical applications. Here, we have developed a Ni-Mn-Fe-In shape memory microwire, exhibiting an ultra-low stress-hysteresis and huge tensile superelasticity in a wide temperature range. The microwire shows a smooth surface and a single crystal structure (with ⟨001⟩A-oriented along the axial direction of microwire), and the microstructure of the microwire contains austenite matrix and sparsely distributed precipitates with an average size of 20–80 nm, all of which may be beneficial to obtain low hysteresis and large strains in the microwire. As a result, the microwire exhibits a minimum stress-hysteresis of as low as 8.5 MPa (with overall strain of 15.3%) and corresponding energy dissipation as low as 1.44 MJ/m3. The microwire always shows a low stress-hysteresis (less than 24 MPa) and low energy dissipation (less than 2.86 MJ/m3) above room temperature. The microwire shows a huge superelasticity with recoverable strains higher than 15% in the wide temperature range from 218 to 418 K. Together with the advantages of easy fabrication and no post-processing required, this microwire shows a tremendous potential for cyclic actuators and energy conversion devices under multi-field coupling.

HIGH-FREQUENCY METHODS FOR COMPLEX AIRBORNE RADAR OBJECTS SCATTERING CHARACTERISTICS CALCULATING

The current state of radar to perform detection and recognition tasks development requires knowledge of a priori information about the secondary radiation of radar objects characteristics. Obtaining this information concerning the target is possible by means of physical or mathematical modelling. Information concerning radar objects obtained by conducting field and physical experiments is associated with significant material, organizational and time costs. Therefore, the method of mathematical modelling can be considered as the most affordable way to obtain information on scattering characteristics. This paper evaluates modern high-frequency methods for the scattering characteristics (secondary radiation) calculating on complex airborne radar objects by mathematical modelling. The calculation of the objects scattering characteristics with surface breaks is carried out by preliminary dividing the surface into a smooth part and edge areas of the surface. The corresponding mathematical relations obtained can be used to estimate the secondary radiation of a complex airborne radar object. The article defines the possibilities of modern high-frequency methods for calculating the scattering characteristics of complex airborne radar objects using mathematical modelling, namely: calculation of scattering characteristics by a smooth surface of a complex airborne radar object; calculation of the scattering characteristics by the edge local surface areas with a radio-absorbing coating of a complex airborne radar object. The scattering characteristics of objects with surface breaks are calculated by first dividing the surface into a smooth part and edge areas. To calculate the scattered field, Kirchhoff-type integral representations are used. Thus, the integration surface covering the scattered in these integral representations is chosen to coincide with the object's surface everywhere except for some edge area. The corresponding mathematical relations for scattering characteristics calculating on smooth and edge localized surface areas of a complex airborne radar object are obtained. The presented calculation methods application can contribute to obtaining a priori information (as required by the current state of radar development) concerning the scattering characteristics of complex airborne radar objects, taking into account such complicating factors as the heterogeneity of the boundary surface, the presence of radio-absorbing coatings, and taking into account their complex effect.

Lattice Boltzmann study of the effect of metal foam on bubble behavior and heat transfer performance in flow boiling

Metal foams with high porosity, light weight, and large specific surface area can significantly enhance heat transfer performance. In this study, the lattice Boltzmann method coupled with the finite difference method is used to investigate the flow boiling characteristics of metal foam surface. Focus is given on the effects of Reynolds number, gravitational acceleration, wall superheat, and metal foam thickness on heat transfer performance. Studies show that increasing the Reynolds number enhances convective heat transfer on the metal foam surface but inhibits bubble nucleation. Compared with a smooth surface, the metal foam takes full advantage of the fluid shear force induced by the high-velocity fluid in the channel-center region, thereby reducing the dependence on buoyancy for bubble detachment. As the wall superheat and metal foam thickness increase, the wake effect induced by bubble detachment is enhanced. Subsequently, bubble detachment is facilitated and the liquid supply is enhanced. These results provide theoretical and applied technical guidance for the structural design of novel metal foam surfaces.

Transforaminal lumbar interbody fusion subsidence: computed tomography analysis of incidence, associated risk factors, and impact on outcomes.

The aims of this study were to 1) define the incidence of transforaminal lumbar interbody fusion (TLIF) interbody subsidence; 2) determine the relative importance of preoperative and intraoperative patient- and instrumentation-specific risk factors predictive of postoperative subsidence using CT-based assessment; and 3) determine the impact of TLIF subsidence on postoperative complications and fusion rates. All adult patients who underwent one- or two-level TLIF for lumbar degenerative conditions at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Patients with traumatic injury, infection, malignancy, previous fusion at the index level, combined anterior-posterior procedures, surgery with greater than two TLIF levels, or incomplete follow-up were excluded. Interbody subsidence at the superior and inferior endplates of each TLIF level was directly measured on the endplate-facing surface of both coronal and sagittal CT scans obtained greater than 6 months postoperatively. Patients were grouped based on the maximum subsidence at each operative level classified as mild, moderate, or severe based on previously documented < 2-mm, 2- to 4-mm, and ≥ 4-mm thresholds, respectively. Univariate and regression analyses compared patient demographics, medical comorbidities, preoperative bone quality, surgical factors including interbody cage parameters, and fusion and complication rates across subsidence groups. A total of 67 patients with 85 unique fusion levels met the inclusion and exclusion criteria. Overall, 28% of levels exhibited moderate subsidence and 35% showed severe subsidence after TLIF with no significant difference in the superior and inferior endplate subsidence. Moderate (≥ 2-mm) and severe (≥ 4-mm) subsidence were significantly associated with decreases in cage surface area and Taillard index as well as interbody cages with polyetheretherketone (PEEK) material and sawtooth surface geometry. Severe subsidence was also significantly associated with taller preoperative disc spaces, decreased vertebral Hounsfield units (HU), the absence of bone morphogenetic protein (BMP) use, and smooth cage surfaces. Regression analysis revealed decreases in Taillard index, cage surface area, and HU, and the absence of BMP use predicted subsidence. Severe subsidence was found to be a predictor of pseudarthrosis but was not significantly associated with revision surgery. Patient-level risk factors for TLIF subsidence included decreased HU and increased preoperative disc height. Intraoperative risk factors for TLIF subsidence were decreased cage surface area, PEEK cage material, bullet cages, posterior cage positioning, smooth cage surfaces, and sawtooth surface designs. Severe subsidence predicted TLIF pseudarthrosis; however, the causality of this relationship remains unclear.

Melt-extruded biocompatible surgical sutures loaded with microspheres designed for wound healing

Sutures are commonly used in surgical procedures and have immense potential for direct drug delivery into the wound site. However, incorporating active pharmaceutical ingredients into the sutures has always been challenging as their mechanical strength deteriorates. This study proposes a new method to produce microspheres-embedded surgical sutures that offer adequate mechanical properties for effective wound healing applications. The study used curcumin, a bioactive compound found in turmeric, as a model drug due to its anti-inflammatory, antioxidant, and anti-bacterial properties, which make it an ideal candidate for a surgical suture drug delivery system. Curcumin-loaded microspheres were produced using the emulsion solvent evaporation method with polyvinyl alcohol (PVA) as the aqueous phase. The microspheres’ particle sizes, drug loading (DL) capacity, and encapsulation efficiency (EE) were investigated. Microspheres were melt-extruded with polycaprolactone and polyethylene glycol via a 3D bioplotter, followed by a drawing process to optimise the mechanical strength. The sutures’ thermal, physiochemical, and mechanical properties were investigated, and the drug delivery and biocompatibility were evaluated. The results showed that increasing the aqueous phase concentration resulted in smaller particle sizes and improved DL capacity and EE. However, if PVA was used at 3% w/v or below, it prevented aggregate formation after lyophilisation, and the average particle size was found to be 34.32 ± 12.82 μm. The sutures produced with the addition of microspheres had a diameter of 0.38 ± 0.02 mm, a smooth surface, minimal tissue drag, and proper tensile strength. Furthermore, due to the encapsulated drug-polymer structure, the sutures exhibited a prolonged and sustained drug release of up to 14 d. Microsphere-loaded sutures demonstrated non-toxicity and accelerated wound healing in the in vitro studies. We anticipate that the microsphere-loaded sutures will serve as an excellent biomedical device for facilitating wound healing.

Predictive Modeling of UV-C Inactivation of Microorganisms in Glass, Titanium, and Polyether Ether Ketone

Biomaterials consist of both natural and synthetic components, such as polymers, tissues, living cells, metals, and ceramics. Their purpose is focused on repairing or replacing malfunctioning living tissues and organs. Therefore, it is imperative to ensure the safety and sterility of biomaterials before any contact with living tissue. Ultraviolet (UV)-C irradiation for biomaterial disinfection has been considered due to the high recurrence rate of bacterial infections and to prevent resistance. Physical composition and surface properties and UV-C sensitivity of microorganisms can alter its efficacy. The main objective of this study was to evaluate the efficacy of UV-C in terms of microbial lethality and additional underlying factors contributing to its performance, namely the surface properties. For this purpose, twelve different strains were first screened, from which four microorganism species known to have the ability to cause nosocomial infections were further tested, namely Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida glabrata. These microorganisms were inoculated onto slides and disks of various bio contact surfaces, including glass (GLS), titanium (Ti), and poly ether etherketone (PEEK), and exposed to UV-C. The results demonstrate that bacterial pathogens on biomaterial surfaces respond differently to UV-C light exposure, and the bactericidal effect decreased in this order: glass, PEEK, and Ti (0.5 to 2.0 log reduction differences). P. aeruginosa ATCC 27853 on glass surfaces was reduced to an undetectable level after being exposed to 6.31 J.cm−2 of UV-C, displaying the highest reduction rate observed among all the tested microorganisms, 2.90 J−1.cm−3, compared to Ti and PEEK. Similarly, a higher reduction in C. glabrata ATCC 2001 was observed on glass; the modeled inhibition displayed a rate of 1.30 J−1.cm−3, the highest observed rate among yeast, compared to Ti and PEEK, displaying rates of 0.10 J−1.cm−3 and 0.04 J−1.cm−3, respectively. The inactivation rates were higher for less hydrophobic materials with smoother surfaces as compared to biomaterials with rougher surfaces.

The Reconstruction of Pt(001) Surface and the Shell-Like Reconstruction of the Vicinal Pt(001) Surfaces Revealed by Neural Network Potential.

In this work, a highly accurate neural network potential (NNP) is presented, named PtNNP, and the exploration of the reconstruction of the Pt(001) surface and its vicinal surfaces with it. Contrary to the most accepted understanding of the Pt(001) surface reconstruction, the study reveals that the main driving force behind Pt(001) quasi-hexagonal reconstruction is not the surface stress relaxation but the increased coordination number of the surface atoms resulting in stronger intralayer binding in the reconstructed surface layer. In agreement with experimental observations, the optimized supercell size of the reconstructed Pt(001) surface contains (5×20) unit cells. Surprisingly, the reconstruction of the vicinal Pt(001) surfaces leads to a smooth shell-like surface layer covering the whole surface and diminishing sharp step edges.

Interfacial improvement of diamond through epitaxial lateral overgrowth with periodic Ir/SiO2/Ir stripe mask

Epitaxial lateral overgrowth (ELO) of diamond films with SiO2 stripe mask has been carried out through microwave plasma chemical vapor deposition systems. To solve the peel-off of SiO2, this study evaluates different kinds of metal buffer layers and chooses Ir as the optimal metal. The effects of the interface feature of two types of stripe masks (Ir/SiO2 and Ir/SiO2/Ir stripes) on the internal stress status and the fluorescence properties are characterized. The optical image confirms that the diamond emerges in the interval of stripes at the initial growth stage and then forms a continuous film with smooth surface and step-flow mode after 37 h lateral overgrowth. Photoluminescence (PL) mapping demonstrates that the SiO2 mask is etched by H2 plasma and results in a high SiV− intensity, especially above the mask. The Ir cap layer on the Ir/SiO2 mask surface is effective in preventing the SiO2 from being etched in the plasma atmosphere, greatly alleviating the PL intensity of the SiV− color center compared with that of the Ir/SiO2 mask. In addition, the Ir cap layer can suppress the stress in the epitaxial layer. The findings of this study can advance the existing research on ELO technology and be potentially applied to vacancy-related color centers.

SPATIAL DISTRIBUTION OF MOLAR INCISOR HYPOMINERALIZATION (MIH) OPACITIES IN FIRST PERMANENT MOLARS

Aim: To evaluate the spatial distribution of MIH opacities in first permanent molars (FPM). Materials and methods: an analysis of intraoral photographs of FPM with demarcated MIH opacities was conducted. The presence of opacity was computed in a digital matrix, discriminating the anatomical regions of the FPM surfaces. The frequencies of distribution of the opacities were descriptively analyzed through 227 FPM digital images of 89 children built in GIMP and Python and by Spearman correlation (= 0,05). Results: the occlusal surface was the most affected one (94% to 100%). In the upper FPM, the palatine surface was the second most affected one (84%-91%). In the lower FPM, the vestibular surface was the second most affected one (85%-80%). A similar pattern of opacity distribution was observed in the contralateral teeth. On smooth surfaces, opacities were more frequent in the regions closer to the occlusal surface than to the cervical one. Conclusion: MIH opacities were mostly present on occlusal, vestibular, and lingual/palatine surfaces, respectively. There is a possibility that the occurrences are in accordance with the chronology of dental formation. Keywords: Molar Incisor Hypomineralization, First Permanent Molars, Dental photography, intraoral photography

Nanofibers loaded levosalbutamol sulfate fast dissolving oral films for sublingual delivery

During allergic reactions, a drug should work quickly and effectively. Levosalbutamol (LSAL) is a short-acting drug that stimulates β2 adrenergic receptors and is commonly used to treat asthma and chronic obstructive pulmonary disease (COPD). This study aimed to prepare sublingual oral patches of levosalbutamol sulfate electrospun nanofibers for ultrafast release. In this study, we fabricated nanofibers by electrospinning polyvinyl alcohol (PVA) polymer (10 %) and different concentrations (3, 5, and 10 %) of LSAL. The nanofibers are randomly aligned, with smooth surfaces and an average fiber diameter of 160, 170, and 198 nm at PVA/LSAL concentrations of 3 %, 5 %, and 10 %, respectively. The in vitro dissolution study showed that all PVA/LSAL nanofibers released the drug ultra-fast (within 5–10 min); 90 % released within 3 min. The folding endurance study revealed that the drug-loaded nanofibers had improved stability. A disintegration study showed that the nanofibers disintegrated rapidly in 1–3 min, and an in vitro cytocompatibility study showed good cell viability with A549 human lung cells. Hence, the proposed fast-dissolving sublingual oral films/patches approach is a promising alternative to existing dosage forms. They can provide an ultra-fast release of various drugs requiring a fast onset of action with increased bioavailability and patient compliance.

Ni-B-PTFE Nanocomposite Co-Deposition on the Surface of 2A12 Aluminum Alloy.

The spinning cup, a crucial component of textile equipment, relies heavily on 2A12 aluminum alloy as its primary raw material. Commonly, electroplating and chemical nickel-phosphorus (Ni-P) plating are employed to improve the surface characteristics of the object. Nevertheless, due to the growing expectations for the performance of aluminum alloys, the hardness and wear resistance of Ni-P coatings are no longer sufficient to fulfill industry standards. This study primarily focuses on the synthesis of Ni-B-PTFE nanocomposite chemical plating and its effectiveness when applied to the surface of 2A12 aluminum alloy. We examine the impact of the composition of the plating solution, process parameters, and various other factors on the pace at which the coating is deposited, the hardness of the surface, and other indicators of the coating. The research findings indicate that the composite co-deposited coating achieves its optimal surface morphology when the following conditions are met: a nickel chloride concentration of 30 g/L, an ethylenediamine concentration of 70 mL, a sodium borohydride concentration of 0.6 g/L, a sodium hydroxide concentration of 90 g/L, a lead nitrate concentration of 30 mL, a pH value of 12, a temperature of 90 °C, and a PTFE concentration of 10 mL/L. The coating exhibits consistency, density, a smooth surface, and an absence of noticeable pores or fissures. The composite co-deposited coating exhibits a surface hardness of 1109 HV0.1, which significantly surpasses the substrate's hardness of 232.38 HV0.1. The Ni-B-PTFE composite coating exhibits an average friction coefficient of around 0.12. It has a scratch width of 855.18 μm and a wear mass of 0.05 mg. This coating demonstrates superior wear resistance when compared to Ni-B coatings. The Ni-B-PTFE composite coating specimen exhibits a self-corrosion potential of -6.195 V and a corrosion current density of 7.81 × 10-7 A/cm2, which is the lowest recorded. This enhances its corrosion resistance compared to Ni-B coatings.