Formation Of Thin Layer Research Articles

SILAR deposited cadmium sulphide (CdS) over graphitic carbon nitride (g-C3N4) based photo-enhanced triboelectric nanogenerator for self-powered visible light photodetector

Self-powered visible-light photodetectors have gained prominence as sustainable solutions across multiple domains, including optical communication systems, biomedical imaging, and optical interconnections. In this study, we presented a self-powered visible-light photodetector in the form of a triboelectric nanogenerator (TENG), which comprises of g-C3N4/CdS over the indium tin oxide coated poly(ethylene terephthalate) (ITO/PET) sheet and aluminum. Firstly, the as-synthesized g-C3N4 was coated over ITO/PET and thereafter the CdS layer was deposited over g-C3N4 layer by using Successive Ionic Layer Adsorption and Reaction (SILAR) method. The formation of CdS thin layer has been confirmed through various characterization techniques, including SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction), and Raman spectroscopy. The as-fabricated TENG exhibits 29.6 V of open circuit voltage (Voc) and 0.55 µA short circuit current (Isc), when subjected to force through finger tapping. Furthermore, the TENG demonstrates a calculated power density of 2.16 µW/cm2 with an external load of 45 MΩ. The TENG’s output performance achieved a significant improvement, reaching 55 V Voc, when exposed to visible light. This enhancement is credited to the mutual coupling effect and enhanced interfacial interactions, fostering a charge-trapping mechanism. The exceptional efficiency of our fabricated TENG establishes itself as a highly productive hybrid system for developing self-powered system, particularly serving as a self-powered visible-light photodetector.

Mixed phase iron oxides thin layers by atmospheric-pressure chemical vapor deposition method

This paper provides a simple method for producing a metal oxide thin layer methodology by atmospheric pressure chemical vapor deposition (APCVD) synthesis over stainless steel substrates. This methodology enables the formation of thin iron oxide layers at its performance at various temperatures of 330 °C, 430 °C, and 530 °C. The deposition arises from thermal decomposition of the iron organometallic precursor Fe3(CO)12, forming a thin layer of iron oxide is, by the ozone present in the reaction chamber promoting the deposition of the iron oxide particles over the substrate. The Raman characterization suggest that at 330 °C, a mixture of hematite and magnetite is predominant on the as deposited substrates, also hematite modes show to be more pronounced as the band at 300 cm-1 narrows. Conversely, magnetite is prominent at higher synthesis temperatures, exhibiting a more intense Eg5 mode at 680 cm-1. The particles exhibit a uniform morphology, with both metal oxide phases coexisting. The average diameter of the particles is 50 nanometers as scanning electronic microscopy shows in a transversal sample section.•The formation of particles is attributed to the combination of iron ions +2 and +3 in the deposition process and their interaction with oxygen in the given synthesis parameters at atmospheric pressure chemical vapor deposition (APCVD).

Enhancing Anode Reversal Tolerance by Low-Carbon and Carbon-Free Anode Catalyst Layers for Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs), as the main hydrogen utilization device, are considered a powerful tool for accelerating a carbon-neutral society. However, durability and cost are the two main obstacles to the commercialization of PEMFCs. Specifically, the anode reversal has been extensively studied as a severe issue that deteriorates the performance and durability of PEMFCs and leads to cell failure. Commercially, iridium oxide (IrOx) or iridium black is intensively utilized as oxygen evolution reaction catalysts to fabricate reversal tolerant anodes (RTAs) despite the slight performance loss. However, previous studies concentrated on investigating the origin or phenomena during the cell-reversal, the key factors and mechanisms affecting the anti-reversal performance, and the interaction among the anode catalyst layer components are still yet to be explored.Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. First, we synthesized Ir outside Ir/Pt/C and Pt outside Pt/It/C with uniform nanoparticle size and distribution and characterized them comprehensively. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing that higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. In addition, Ir outside Ir/Pt/C shows better reversal tolerance than Pt outside Pt/It/C, which has been rarely mentioned in previous studies. Further, the experimental results show that even though the metal coverage is high, the performance degradation caused by carbon corrosion is still inevitable. On this basis, we synthesized a high specific surface area conductive oxide Ti4O7 as the anode catalyst support to eliminate the adverse effects of carbon corrosion. Previously, the initial performance of Ti4O7-supported catalyst was obstructed by the disadvantaged electrical conductivity of Ti4O7. We obtain a comparable polarization performance after optimizing the Ti4O7-supported anode catalyst layer parameters by shortening the electron transfer pathway and increasing metal coverage. Typically, the Ir@IrOx/Pt/Ti4O7-fabricated RTA with low Ir loading displays approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than a conventional carbon-supported counterpart. The degradation origin of the Ti4O7-supported anodes is also studied by postmortem characterizations, pointing to the Pt oxidation caused by the formation of TiOx thin layers on the Pt surface. These two works aim to promote the development of highly durable and reversal tolerance anode and provide a bright perspective for practical high-performance, low-degradation, and cost-friendly RTA fabrication.

Formation of Thin GaAs Buffer Layers on Silicon for Light-Emitting Devices

Formation of Thin GaAs Buffer Layers on Silicon for Light-Emitting Devices

Correlation between AFM characterizations and dynamic mechanical testing to assess the ductile-to-brittle transition during ABS photodegradation

The extensive use of Acrylonitrile Butadiene Styrene (ABS) raises challenges due to its vulnerability to oxidative degradation, primarily impacting its mechanical behavior. Photodegradation appears to be the pivotal driver in this degradation process. The main aim of the present study is to provide a comprehensive approach to the underlying mechanisms governing the transition from ductile to brittle behavior in ABS after exposure to UV-induced photodegradation. This study thus focuses on the multiphase nature of ABS, wherein polybutadiene (PB) nodules are dispersed within a matrix of styrene-acrylonitrile. Dynamic mechanical tensile tests have been employed to highlight aged layer mechanical impact by blocking the dissipative response of the matrix and applying a homogenous stress field, while atomic force microscopy (AFM) has been used to characterize the local mechanical properties of ABS finely. The evolution of global mechanical properties has been correlated with changes in microstructural behavior. One of the main contributions of the present work is the correlation between the formation of brittle layers with the brittle state of aged ABS. Mechanical testing using dynamical tensile test revealed a critical aging time marking the transition from a ductile to a brittle state of the 450 µm thick samples. Chemical analysis using infrared spectroscopy revealed evolutions in the material composition, especially in the carbonyl, hydroxyl, and PB unsaturation groups. Distinct thin oxidized layers on each exposed surface were observed using optical microscopy. Finally, AFM analysis on the exposed surface shows the stiffening of PB nodules, indicating the formation of brittle thin layers due to oxidation causing an apparent fragile behavior of ABS.

Surface Evaluation of Tricalcium Phosphate Bioceramic Coating on SS-316L by Electrophoretic Deposition

The development of orthopedic implant materials has become an important topic of discussion lately. The SS-316L alloy is widely used as an implant material due to its relatively low cost, corrosion resistance, and ease of production. However, metal alloys, especially SS-316L, are prone to ion release into the blood over time. Therefore, TCP or tricalcium phosphate [Ca3(PO4)2] is needed to coat the surface of SS-316L, preventing ion release into the blood and enhancing the biocompatibility of the implant material. In this study, TCP coating was applied to the SS-316L substrate using the electrophoretic deposition technique. The influence of deposition time on changes in microstructure and mechanical properties is the main focus of this study. The results of the coating technique indicate that the deposition yield increases with the deposition time. Morphological testing results show that increasing deposition time improves coating quality by increasing the thickness of the coating layer and preventing layer peeling. The coating process also reveals the accumulation of layers in certain areas and the formation of thin layers in other regions. A deposition time of 30 minutes results in a coating thickness ranging from 48.7 to 57.9 µm. Hardness testing, conducted with indentation loads of 50, 100, and 300 gf, indicates that longer deposition times and higher indentation loads during hardness testing result in reduced material hardness.

Cationic surfactant-assisted foam fractionation enhances the removal of short-chain perfluoroalkyl substances from impacted water

Several studies have demonstrated that air-bubbling and foam fractionation techniques can efficiently remove long-chain PFAS from contaminated water. However, removing short-chain PFAS is challenging due to its lower surface activity and inability to form self-assembly structures at the air-water interface. In this study, we tested various additives, including salts, surfactants, and polymers, to improve short-chain PFAS (e.g., perfluorobutanesulfonic acid (PFBS) and perfluorobutanoic acid (PFBA)) removal in non-foaming solutions using a bench-scale system. We found that in the presence of cetyltrimethylammonium chloride (CTAC) and salt, air-bubbling can significantly remove 0.5 μg L−1 of PFBS and PFBA in deionized water by >99% (15 min) and 81% (60 min), respectively. The decline of surface tension and the formation of thin foam-like layers during bubbling, controlled by the concentration of CTAC, significantly improved the removal of short-chain PFAS. Adding anionic and neutral surfactants showed no removal of short-chain PFAS during bubbling, suggesting the importance of the electrostatic interactions between short-chain PFAS and the cationic CTAC. We observed a 1:1 M ratio between CTAC and PFBS removed from the solution, suggesting the formation of ion pairs in the solution and enhancing the surface activity of the overall neutral (PFAS-CTAC) complex. A mass balance of the system revealed that the primary mechanism by which PFAS was removed from non-foaming waters was through aerosol generation (70−100%). Using the optimized condition, PFAS mixtures (short- and long-chain PFAS, including five recently regulated PFAS by USPEA, 2 nM each) in deionized water and natural groundwater were successfully removed to below detection (>99% removal; <2 ng L−1), except for PFBA (25−73% removal). These results provide an improved understanding of the mechanism by which PFAS is removed during foam fractionation and highlight the need for capturing aerosols enriched with PFAS to prevent secondary contamination.

Studies of erosion-deposition of plasma-facing materials due to plasma-wall interactions in EAST tokamak

Material erosion, migration, mixing, dust formation, and co-deposition were investigated on plasma-facing materials in the experimental advanced superconducting tokamak (EAST). The test samples (TSs) of molybdenum (Mo), tungsten (W), and carbon (C) were irradiated during EAST operations. All exposed TS surfaces are modified by erosion and deposition processes resulting in the formation of thin layers containing a mixture of PFCs (Mo, W, Cu, Cr, Fe) and light elements (Li, C, Ca, N, O). The majority of chemical species are in a layer of thickness <650–900 nm. The particle size and structure of co-deposition were observed on each TS. Depth profiling by laser-induced breakdown spectroscopy (LIBS) suggests the presence of local and global impurities on the TSs resulting from the plasma-wall interaction (PWI). The processes involved in the PWI that caused erosion of EAST materials are heat flux and high energy excited impurity particles. The material is sputtered from the first wall plasma-facing components. Erosion and deposition processes occur simultaneously in the EAST. The migrated impurities get deposited globally on remote surfaces. A crack was observed in one of the W TSs due to a high heat load. The spectral intensity of co-deposition and substrate continuously changed during successive laser shots.

A study of pomegranate peel extract effect on corrosion inhibition performance on aluminum in HNO3 solution

Green corrosion inhibitors have an important role in reducing the corrosion rate of metals and the effects of toxic chemicals in the environment. In this study, the inhibition effect of pomegranate peel extract (PPE) with concentration of 0.5, 1, 1.5, 2, 2.5 and 3 g/L on the aluminum 1050 alloy corrosion behavior in the nitric acid solution investigates using the weight loss, electrochemical techniques, scanning electron microscope (SEM), atomic force microscope (AFM), contact angle images, gas chromatography-mass spectrometer (GC-MS) analysis, fourier transform Infrared spectroscopy (FTIR) and ultraviolet radiation (UV-IR). And, the (UV-IR), (GC-MS), and FTIR results confirm the presence of many organic compounds (Containing the N, S, and O atoms), which are responsible for inhibitor performance and absorption phenomena. Meanwhile, the electrochemical impedance results (EIS) indicate that the double layer capacity decreases and the corrosion resistance (Corrosion current density (icorr) from 0.128 to 0.009 mA/cm2) increases with the increase of the inhibitor concentration (The inhibition efficiency increased with increasing the inhibitor concentration from % 54.29 to the % 92.58 at (1–3 g/L). In addition, the corrosion current density decreases with the increase of the inhibitor concentration using the potentiodynamic polarization (PDP) test. However, the corrosion rate enhances with increasing the temperature. From the other hand, quantum chemical (QC) calculation and molecular dynamics (MD) simulation perform to investigate the theory of the adsorption mechanism. According to these studies, the adsorption of PPE on the aluminum 1050 alloy surface is agreement with the langmuir isotherm and as a result it is a mixed-type inhibitor. In final the SEM and AFM results show that the corrosion rate of the aluminum 1050 alloy surface is significantly reduced after the addition of the inhibitor to the corrosive environment. Furthermore, the contact angle image shows that the inhibited aluminum surface has a hydrophobic property in an aqueous solution. And, the QC calculation and MD simulation clarify well the thin layer formation due to the good adsorption of inhibitor (PPE) on the surface of aluminum 1050 alloy in the nitric acid solution, theoretically. It is concluded that PPE will inhibit the surface of aluminum against the corrosion agents in acidic environment and can use as a green inhibitor.

Electronic structure and composition of tin oxide thin epitaxial and magnetron layers according to synchrotron XANES studies

The materials of the tin-oxygen system and thin-film structures based on them are modern and actual for the creation of a wide range of electronic devices, for example, resistive gas sensors of high sensitivity and short response time with low energy consumption and high manufacturability. An important direction in the study of such materials and structures is the control of properties with variations in technological formation regimes. Information on the composition, local atomic and electronic structure of thin layers of the tin-oxygen system with varying approaches to their production is in demand. The work is devoted to the study of the electronic structure of thin layers of tin oxides obtained by modern methods of molecular beam epitaxy and magnetron sputtering. A study of the local partial density of electronic states in the conduction band by X-ray absorption near edge structure spectroscopy of tin and oxygen has been carried out. The data were obtained using high-intensity synchrotron radiation, which allows varying the monochromatized radiation quantum energy without loss in intensity, that is necessary to obtain high-resolution X-ray spectral data. It is shown that the composition, local atomic surrounding, electronic spectrum and their features depend on the technology of formation and storage conditions of the studied structures. Synchrotron X-ray spectroscopy data show the presence of intermediate oxides of the tin-oxygen system in the studied materials after prolonged storage in laboratory conditions. The data obtained indicate the possibility of controlled variation in the composition, local atomic surrounding and electronic spectrum of thin-film structures of tin oxides of small thickness. The results of the work can be used in the formation and subsequent modification of thin and ultrathin layers of tin oxides by magnetron sputtering and molecular beam epitaxy, as well as in their further application as active layers of microelectronics devices

Water recovery from the high salinity brine: Effect of the interlayer structure in the polyamide nanofiltration membrane

Water recovery by nanofiltration (NF) from the high salinity brine is emerging as a promising technology to alleviate the water shortage. Thin film composite membranes with polyamide (PA) selective layer are the mainstream in the field of NF. Nevertheless, the trade-off between permeance and retention as well as the structural stability of the mainstream PA membrane still restrict their widespread application. Herein, a novel interlayered thin-film nanocomposite (TFNi) nanofiltration membrane was fabricated based on the interfacial polymerization. The PDA@MXene hybrid was employed as the interlayer to modulate the adsorption and diffusion process of amine monomers, giving rise to the formation of thin and rough PA selective layer, which could accelerate the transport of water molecules. Moreover, PM-TFNi membrane demonstrated higher crosslinking degree and more negatively charged surface, significantly benefiting the repulsion of inorganic salt ions. In this context, PM-TFNi membrane rendered a competitive permselectivity with the water flux of 18.3 L m−2 h−1 bar−1 and the Na2SO4 rejection of 98.0%. In addition, PM-TFNi membrane exhibited distinguished long-term stability and pH resistance. Overall, this work would provide a paradigm shift in designing high-performance and robust NF membrane for the water treatment.

Investigation of mechanical and tribological performance of wood dust reinforced epoxy composite under dry, wet and heated contact condition

Abstract Natural fibers have received a lot of attention from academia as well as industry in the context of sustainable materials. Since they are more environmentally friendly than traditional synthetic materials, their physico-mechanical and frictional properties such as porosity, moisture absorption, high strength, modulus, toughness, and wear resistivity make them appropriate for a variety of industrialized applications where issues involving a significant quantity of dumping must be taken into account. The paper introduces an attempt to use epoxy-based composites reinforced with wood dust for various applications. The composites are prepared with various wood filler stacks (0, 2.5, 5, 7.5, 10, and 12.5 wt%) embedded with epoxy resin and subjected to tensile and flexural testing. The highest ultimate tensile strength achieved at 7.5 wt% wood dust support is 22 MPa, whereas the highest flexural modulus is 0.48 GPa at 12.5 wt% composites. The composite’s wear properties is examined under dry, wet, and heated contact conditions using a pin-on-disk (POD) machine. In dry condition, coefficient of friction (COF) varies from 0.10 to 0.38 whereas, in wet condition, the value of COF decreased by 70–83 %. In heated state, the COF is increased by up to 15 % when varying the temperature from 40 °C to 80 °C. The composite exhibits better wear behavior in the lower filler support than in the higher filler support due to the sturdy connection between the matrix and filler. On the other hand, the wet state’s tribological performance is superior to the dry and heated states. During surface morphology analysis, it is found that various voids, crack formation, wear debris, and thin transfer layer formation take place on the composite.

Thermal stabilizing and toughening of a dual-phase Nb alloy by tuning stabilizing element C in Nb-BCC

Niobium alloys have found extensive application in industries, such as aerospace, nuclear reactor, and emerging electronic technologies, owing to their high melting point, low density, and remarkable formability. Nevertheless, they still fall short in terms of comprehensive strength, toughness, and thermal stability when subjected to complex impacts and/or torsional forces during service. Here, a dual-phase (BCC/FCC) Nb alloy with attractive mechanical properties and thermal stability was designed by tuning stable element C in the Nb-BCC matrix assisted by hot deformation and aging processes. Our findings reveal that the formation of discontinuous carbides at the grain boundary promotes the phase transformation of the matrix from BCC to FCC (K-S orientation relationship), resulting in the formation of FCC thin layers and nano particles. This unique configuration hinders the slipping of dislocations during deformation and impedes the degeneration of microstructures during the thermal cycling process from 200 °C to 900 °C. Moreover, the discontinuous carbides at GBs provide channels to transfer dislocations between various phases and/or grains, which results in attractive mechanical properties and thermal stability. The ultimate tensile strength, yield strength, elongation, and elasticity modulus of the designed Nb alloy reach impressive values of 790.5 MPa, 436.5 MPa, 39.1 %, and 63.5 MPa, respectively. These observations provide guidelines for designing dual-phase Nb alloys with remarkable strength, toughness, and thermal stability for aerospace applications by tuning the stabilizing element C in the Nb-BCC matrix.

Enhanced corrosion resistance of CoCrMo by laser-based surface modification

Biomedical grade cobalt–chromium–molybdenum (CoCrMo) alloys are extensively used for load-bearing biomedical applications such as hip and knee implants due to their exceptional biocompatible and biomechanical properties. However, the strain-induced martensite ε-phase development during contact loading results in thin oxide layers that are prone to fracture leading to corrosion. The formation of thin oxide layers is undesirable for long-term deployment. We employed laser-texturing to enhance the corrosion resistance of the material in simulated body fluid by the formation of hcp ε-phase martensite and via the formation of oxide layers. However, partial formation of hcp ε-phase martensite was observed. By means of central composite design-based response surface methodology, three laser parameters such as average laser power, texture density and the number of passes were optimised for maximal open circuit potential, an indicator for minimal corrosion. The textured surfaces were found to assist in the cellular proliferation of fibroblasts and inhibit bacterial growth.

Design of thin-film nanocomposite membranes via synchronizing interfacial coordination and polymerization reactions for organic solvent nanofiltration

Thin-film nanocomposite (TFN) membranes have received immense research interest due to their high permeability and high selectivity in organic solvent nanofiltration (OSN). Herein, TFN membranes were fabricated by synchronizing interfacial coordination and polymerization reactions occurring at an ionic liquid/water interface. The one-pot interfacial reactions led to the simultaneous formation of Fe-MeIm nanofillers and polyamide thin layers with uniform dispersion and good compatibility. The resultant ternary membranes were denoted as Fe-MeIm/PA/PMIA, wherein the Fe-MeIm nanofillers were well-encapsulated in the ultrathin PA selective layer and both of them were located on top of the solvent-resistant PMIA substrate. The morphologies, microstructure, physicochemical properties, and OSN performance of the resultant TFN and traditional TFC membranes were systematically studied and compared. Moreover, the effects of the concentrations and ratios of reagents during the one-pot interfacial reactions were also elucidated. The optimal TFN membrane showed 5 times higher permeance than the TFC membrane without nanofillers while maintaining a high rejection for Congo red/ethanol separation. Moreover, it also showed good stability in various solvents and long-term stability and remarkably improved mechanical properties. This work provides a novel and time-saving fabrication strategy for TFN membranes for OSN application.

Double active sites promoting hydrogen evolution activity and stability of CoRuOH/Co2P by rapid hydrolysis

Cobalt-based phosphides show excellent hydrogen evolution reaction (HER) performance, however, improving the intrinsic activity and stability of it in alkaline electrolyte still remains a challenge. Herein, CoRuOH/Co2P/CF with heterojunction structure was developed by means of molten salt and rapid hydrolysis (30 s). The OH− from rapid surface hydrolysis of Co2P as a hydrogen adsorption site can facilitate the formation of thin CoRuOH layer as a water dissociation site, which may bring out better synergistic effect for alkaline HER. Moreover, the covering of CoRuOH can improve the stability of Co2P for HER. When drives at 100 mA/cm2, it only requires overpotential of 81 mV in 1.0 mol/L KOH (25 °C). Even at higher current density (1000 mA/cm2), CoRuOH/Co2P/CF can also operate stability for at least 100 h. When coupling with NiFe-LDH/IF in a two-electrode system, the voltage of NiFe-LDH/IF(+) || CoRuOH/Co2P/CF(−) at 1000 mA/cm2 is merely 1.77 V with 100 h, demonstrating great potential for water splitting. The implementation of this work provides a new strategy and reference for the further improvement of transition metal phosphides as HER electrocatalysts.

MICROSTRUCTURE AND OXIDATION BEHAVIOR OF THE OXIDE DISPERSION STRENGTHENED STAINLESS STEEL 316L WITH ZIRCONIA DISPERSION

Synthesis of the oxide dispersion sODS steels was performed by dispersing 0.5 wt % zirconia to the stainless steel SS 316L by the powder metallurgy method. The ball milling process was carried out for pre-alloying the elements continued with the consolidation performed by the compaction and sintering process using the APS (Arc Plasma Sintering). Analysis of microstructure was performed by observing the morphology, identify the phase and evaluate the oxide distribution. An oxidation test was carried out at 700oC for 8 hours using the MSB (Magnetic Suspension Balanced) apparatus to evaluate the primary oxidation curve. The same grain fineness consists of 2 dominant phases, so the presence of an austenitic phase and a ferritic phase has been analyzed from the X-Ray Diffraction pattern. The homogeneous distribution of zirconia was observed, followed by improvements in mechanical properties, which could be identified by hardness testing. The parabolic phenomenon oxidation curve was explained by the excellent high-temperature oxidation behaviour of the ODS steel, followed by the formation of ZrO2 oxide protective thin layer.

The Effect of Platelet Rich Plasma versus MSCs Derived Exosomes on the Healing of Burn Injury in Albino Rat: Histological Study

Abstract Background The clinical treatment of skin loss due to severe and massive burns or wounds continues to be a major problem in surgical procedures. Although different kinds of dressings and therapies have been developed, but most of them are expensive. Therefore, new strategies are needed to promote and help in wound healing and repair. Recent studies have demonstrated that exosomes help tissue repair because of high stability, non immune rejection and easy control of dosage and concentration. Platelet-rich plasma (PRP) is an autologous concentration of platelets in concentrated plasma. It has been used to promote soft and hard tissue healing. Aim to compare the effect of MSCs derived exosomes versus PRP on the promotion of healing of experimentally induced second degree partial thickness burn injury in adult male albino rats. Methods The thirty-two adult male albino rats were divided randomly into 4 groups. Group I (control). Group II (burn injury group) that will be left for spontaneous healing. Group III (burn injury treated with PRP intradermal injection). Group IV (burn injury treated with intradermal MSCs derived exosome). All the animals were sacrificed at 7th day (subgroup a) and 21th day (subgroup b). The skin biopsies will be taken and processed for light microscope examination. Results H&amp;E stained section of untreated burn (subgroup IIa) showed coagulative necrosis in epidermis and papillary layer of the dermis. Sign of epithelial migration from the edge of the wound appeared. In Subgroup IIb the surface of the wound was covered by an eschar that converted partial thickness into complete thickness. This resulted in formation of granulation tissue in the dermis. In Subgroup IIIa showed the formation of thin layer of epidermis containing undifferentiated keratinocytes. The underlying dermis contained collagen fibers and beginning of new hair follicles formation. Some specimens in Subgroup IIIb revealed thin epidermis with incomplete differentiation of keratinocytes. Numerous hair follicles were detected in the dermis. However some specimens showed thickened epidermis with presence of rete ridges. The dermis showed few irregularly distributed collagen fibers in granulation tissue with absence of skin appendages. In exosome treated group (subgroup IVa) showed thin epidermis with well differentiated keratinocytes. The dermis contained collagen fibers with absence of skin appendages. Subgroup IVb was more or less similar to the control group. Conclusion The current study revealed that burn treated exosomes group was better than PRP treated group. In addition PRP treated group revealed hyperplastic changes in epidermis with delay in remodeling phase of burn healing.

Influence of annealing on the structure and wear resistance of coatings produced by cold spraying of Al–SHS7574 powder mixture

In present work, the possibility of fabricating a composite cold-sprayed coatings consisting of partially amorphous alloy reinforcing particles and an aluminum matrix was studied for the first time. A mixture of pure aluminum and SHS7574 powders in a ratio of 50/50 wt% was deposited on aluminum alloy substrates, which ensured the formation of high-quality coating with a porosity of less than 1%. The ratio of SHS7574 alloy to aluminum in the as-sprayed samples was nearly the same as in the initial powder mixture which indicates a similar efficiency of component deposition. Composite coatings were annealed in a vacuum furnace at 540 °C and 600 °C. Microstructure and phase composition of as-sprayed and annealed coatings were examined with XRD, SEM and EDX mapping. Post annealing of the coatings promoted the formation of a reaction layers around the Fe-based alloy particles consisting of Fe2Al5, Fe4Al13, Fe23B5, and Fe5C2 phases. The effect of annealing on the mechanical properties of the Al–SHS7574 coatings was determined by measuring hardness, nanohardness and wear resistance according to ASTM G 133–05. The increase in the samples’ hardness after annealing was associated with the formation of a reaction layers and increase in its thickness with rising annealing temperature. The coating annealed at 600 °C demonstrated the highest hardness due to the formation of thick brittle reaction layers. The preservation of the aluminum matrix with the simultaneous formation of thin reaction layers after annealing at 540 °C reduced the wear rate of the coating despite the moderate hardness.

High performance cellulose acetate/polyamide (CA/PA) thin film composite forward osmotic (TFC‐FO) membranes from dual solvent modification processes

AbstractPolyamide (PA) based thin film composite forward osmotic (TFC‐FO) membranes were prepared through inter‐facial polymerization (IP) processes on porous cellulose acetate (CA) substrates. A dual solvent modification process of adding DMF in the aqueous phase followed by activation with methanol was found to be able to simultaneously improve the permselectivity and anti‐fouling capability of the modified membranes. On top of the acidic CA substrates, DMF could not only absorb the HCl formed in the IP processes, but also chemically bind with the PA matrix by reaction with MPD monomers, leading to formation of homogeneous thin and flat PA layers, while methanol activation further swelled the PA matrix, repaired defects and optimized water permeating channels. Using 1 M NaCl solution as the draw solution, the water flux of the CA/PA‐DMF4‐ME1 membrane was twice that of the pristine membrane, and 24% increase in Jw/Js value from 182 to 225 L·mol−1. Its Jw/Js value could be further increased 10 times to 2000 L·mol−1 using 1 M Na2SO4 solution as draw solution. RO tests for the CA/PA‐DMF4‐ME1 membranes showed 6‐fold increase in water permeance, from 1.16 to 7.02 L·m−2·h−1·bar−1, as well as increase in NaCl rejection from 94.8% to 97.7% from pristine membrane.