Rough Surface Morphology Research Articles

Effect of Roundness and Surface Roughness of Foundry Sand on the Temperature Change of Sand Cores for Aluminum Casting

Organic binder in sand cores, such as phenol-formaldehyde binder, rapidly decomposes above 550 K, releasing gases including volatile organic compounds (VOCs) and hydrocarbon gases. A rapid temperature rise in the core increases gas evolution during the casting process. The roundness and surface roughness of foundry sand particles influence temperature changes in sand cores. This study investigates how these factors affect temperature change in packed sand beds and cores and the gas porosity at the interface between the core and the A356 Al castings. Temperature changes were measured using three types of sand: angular artificial sand (AAS), natural sand (NS) with different roundness and surface roughness, and polished AAS with a smooth surface. Additionally, the temperature rise in cores was measured with varying proportions of AAS. Packed sand beds and cores with low roundness and rough surface morphology form macro and micro-gaps due to high porosity and surface roughness. These gaps, filled with interstitial gas of low thermal conductivity, hinder heat conduction. Delaying the temperature rise of the core could reduce weight loss from binder decomposition, thereby decreasing gas porosity at the interface between the A356 Al castings and the core. These findings on the effects of roundness and surface roughness on temperature changes in packed sand beds and cores provide methods for reducing gas emission during the casting process.

Efficient adsorptive removal of Congo Red dye using activated carbon derived from Spathodea campanulata flowers

This report investigates the preparation, characterization, and application of activated carbon derived from Spathodea campanulata flowers (SCAC) to remove Congo Red (CR) dye from aqueous streams. SCAC was synthesized using orthophosphoric acid activation which yielded a mesoporous material with a specific surface area of (986.41 m2/g), significantly exceeding values reported for flower-derived activated carbons in the available literature. Field emission scanning electron microscopy (FESEM) image revealed an irregular, rough surface morphology pre-adsorption, which became smoother post-adsorption, indicating successful CR attachment. Elemental analysis through energy-dispersive x-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed an increase in carbon content and the appearance of sulfur, verifying CR uptake. Adsorption kinetics obeyed the pseudo-second-order equation, signifying chemisorption, while the equilibrium dataset fitted better to the Langmuir model, with R2 of 0.9944, suggesting a monolayer adsorption mechanism with a maximum adsorption capacity of 59.27 mg/g. Thermodynamic analysis revealed spontaneous and endothermic adsorption process. Desorption studies showed methanol as the most effective desorbing agent, with SCAC retaining considerable adsorption capacity across six cycles, highlighting its reusability. In tests with real water matrices, SCAC demonstrated significantly higher removal efficiency in natural waters than control, suggesting enhanced adsorption in complex matrices. These findings underscore the practical applicability of SCAC in real-world wastewater treatment, offering a promising solution for large-scale industrial applications.

Anchorable Polymers Enabling Ultra-Thin and Robust Hole-Transporting Layers for High-Efficiency Inverted Perovskite Solar Cells.

Currently, the development of polymeric hole-transporting materials (HTMs) lags behind that of small-molecule HTMs in inverted perovskite solar cells (PSCs). A critical challenge is that conventional polymeric HTMs are incapable of forming ultra-thin and conformal coatings like self-assembly monolayers (SAMs), especially for substrates with rough surface morphology. Herein, we address this challenge by designing anchorable polymeric HTMs (CP1 to CP5). Specifically, coordinative pyridyl groups are introduced as side-chains on poly-triarylamine (PTAA) backbone with varied contents by copolymerization method, resulting in chemical interactions between polymeric HTMs and substrates. The strong interaction allows them to be processed into ultra-thin, uniform, and robust hole-transporting layers through employing low-concentration solutions (0.1 mg mL-1, vs. 2.0-5.0 mg mL-1 for conventional PTAA), greatly decreasing charge transport losses. Moreover, upon systematically tuning the pyridyl substitution ratio, the energy levels, surface wetting, solution processability, and defect passivation capability of such anchorable HTMs are simultaneously optimized. Based on the optimal CP4, we achieved highly efficient inverted PSCs with power conversion efficiencies (PCEs) up to 26.21 %, which is on par with state-of-the-art SAM-based inverted PSCs. Furthermore, these devices exhibit enhanced stabilities under repeated current-voltage scans and reverse bias ageing compared with SAM-based devices.

MOCVD growth of β-Ga2O3 with fast growth rates (>4.3 μm/h), low controllable doping, and superior transport properties

Si-doped β-phase (010) Ga2O3 epi-films with fast growth rates were comprehensively investigated using trimethylgallium (TMGa) as the Ga precursor via metalorganic chemical vapor deposition (MOCVD). Two main challenges facing the MOCVD growth of thick (010) β-Ga2O3 films with fast growth rates include high impurity carbon (C) incorporation and rough surface morphologies due to the formation of imbedded 3D pyramid-shaped structures. In this work, two different categories of oxygen source (high-purity O2 > 99.9999% and O2* with 10 ppm of [H2O]) were used for β-Ga2O3 MOCVD growth. Our study revealed that the size and density of the 3D defects in the β-Ga2O3 epi-films were significantly reduced when the O2* was used. In addition, the use of off-axis (010) Ga2O3 substrates with 2° off-cut angle leads to further reduction of defect formation in β-Ga2O3 with fast growth rates. To suppress C incorporation in MOCVD β-Ga2O3 grown with high TMGa flow rates, our findings indicate that high O2 (or O2*) flow rates are essential. Superior room temperature electron mobilities as high as 110–190 cm2/V·s were achieved for β-Ga2O3 grown using O2* (2000 sccm) with a growth rate of 4.5 μm/h (film thickness of 6.3 μm) within the doping range of 1.3 × 1018–7 × 1015 cm−3. The C incorporation is significantly suppressed from ∼1018 cm−3 to <5 × 1016 cm−3 ([C] detection limit) for β-Ga2O3 grown using high O2 (O2*) flow rate of 2000 sccm. Results from this work will provide guidance on developing high-quality, thick β-Ga2O3 films required for high power electronic devices with vertical configurations.

A Study of the Effect of Roughness on the Three-Body Wear Mechanism from a Microscopic Point of View: Asperity Peak Removal

The presence of particles leads to varying degrees of mass loss on a metal sealing surface, which severely affects the seal’s lifespan. Understanding the complex wear mechanism and optimizing the surface roughness morphology are particularly important in engineering. By characterizing the surface of the metal (SS 304) with different roughness parameters Ra, Rp, Rpk, Rpc and Rku, the variation mode of mass loss under abrasive wear conditions was revealed. Unlike traditional two-body wear, the involvement of abrasive particles significantly impacts surface Ra and other surface morphologies (asperity peak features). A contact model for metal rough surfaces, distinct from two-body contact, was established to clarify the changes in removal mechanisms. It was found that the change in the contact between the particle and the asperity peak led to a change in the mass loss and guided the appropriate metal roughness range: Ra 0.05 μm and Ra 0.6–0.8 μm. In addition, it was found that the removal of asperity peaks is holistic under low roughness, and only parts of asperity peaks are removed under high roughness. Notably, the metrological methods used in this study supplement existing roughness measurements. By exploring the complex removal mechanism of asperity peaks, micro-scale guidance for surface (texture) design, machining, and optimization is provided.

Enhanced Triboelectric Outputs from PAN/MoS2 Nanofiber‐Based Nanogenerators for Powering Backscatter Communications in Sustainable 6G Networks

This work explores the development of a triboelectric nanogenerator (TENG) based on polyacrylonitrile (PAN) and molybdenum disulfide (MoS2) nanosheets composite fibers for enhancing tribo‐positive electricity to power backscatter communication systems, contributing to the sustainable internet of things (IoT) nodes in future 6 G networks. By incorporating different concentrations of MoS2 (1, 2, 3, and 4 wt%) nanosheets into PAN nanofibers via electrospinning, the nanocomposite fiber‐based TENGs exhibit improved triboelectric properties. The TENG based on PAN/4% MoS2 nanocomposite fiber mat achieve a peak open‐circuit voltage of 296 V and a short‐circuit current of 6.16 μA, which represents an ≈95% and 77% enhancement, respectively, in comparison with the TENGs based on neat PAN nanofiber mat. The enhanced charge transfer ability at the PAN and MoS2 nanosheet interface, the increased dielectric properties, the rougher surface morphology of the composite nanofibers contribute to the enhancements in triboelectric performance. These TENGs are integrated with the backscatter communication system to power a wireless identification and sensing platform (WISP) tag, demonstrating extended transmission range and improved real‐time data acquisition. These findings suggest that TENGs can play a significant role in sustainable energy solutions for 6 G‐enabled IoT applications.

Impact of phytoceuticals: Thymol-loaded zein-based nano-antimicrobials to combat resistant zoonotic pathogen

Campylobacter jejuni related gastrointestinal infections are challenging to overcome due to emerging antimicrobial resistance that poses global public health concerns. The development of biopolymeric nanosystems encapsulating natural antimicrobials serves as an alternative-medicine based on phytoceuticals. Thymol, an essential ingredient extracted from the thyme plant (Thymus vulgaris), and oregano plant (Origanum vulgare) exhibits a wide range of applications including anti-inflammatory, antibacterial, and antioxidant properties. However, its bioavailability, low stability, and poor water solubility severely limit its applications. Herein, zein nanosystems encapsulating thymol (TH-ZNs) were successfully fabricated to enhance the antibacterial and antibiofilm potential of thymol against foodborne multidrug-resistant C. jejuni. Through the antisolvent precipitation technique, physically stable nanosystems were obtained exhibiting a high encapsulation efficiency of 87 ± 0.5 %. Scanning electron microscopy revealed slightly rough surface morphology of TH-ZNs. FTIR spectroscopy elucidated hydrophobic interactions between thymol and zein which facilitates the successful encapsulation of thymol. Dynamic light scattering (DLS) studies revealed that the entrapment of thymol in ZNs increased the size from 202 ± 1.4 nm to 212 ± 1 nm, whereas zeta potential values were reduced from −42 ± 3 mV to −37 ± 2 mV in the case of void and TH-ZNs, respectively. Furthermore, TH-ZNs exhibited higher antimicrobial and antibiofilm efficacy against C. jejuni as compared to free thymol for a longer period. These results indicate that TH-ZNs inhibited bacterial growth while being non-cytotoxic, thus improving the overall efficiency of phytoceuticals to develop alternative nanotherapeutics to combat the resistant zoonotic pathogen.

Adsorption efficiency and photocatalytic activity of silver sulphide-activated carbon (Ag2S-AC) composites

BackgroundThis study investigates the adsorption efficiency and photocatalytic activity of silver sulphide-activated carbon (Ag2S-AC) composites derived from ground coffee waste (GCW). MethodsIn this work, GCW was preceding to carbonized at 500 ± 2°C for hours and formed biochar. Then, GCW was subjected to activation using hydrochloric acid (HCl), phosphoric acid (H3PO4) and potassium hydroxide (KOH). The mixture was left to soak for 24 h at room temperature, followed by carbonization at 350 and 500˚C. In the meantime, the silver sulphide (Ag2S) was synthesized by using an ion exchange method. Sodium sulphide (Na2S) was used as sulphur source and mixed with silver nitrate (AgNO3) and sodium citrate (NaCit) for two hours, then dried in oven at 50 ± 2°C for 10 h. Next, the carbonized AC was subsequently combined with synthesized silver sulphide, resulting in the creation of Ag2S-activated carbon composites that functioned both as adsorbent and photocatalyst. Their capabilities as adsorbents and photocatalyst were studied by using copper ions (Cu2+) and methylene blue (MB) solution. Significance findingsBased on results, GCW and all the prepared activated carbons are in the amorphous phase, except for the Ag2S-AC composites, where the Ag2S peak reflection can be observed from the X-ray diffraction (XRD) pattern. GCW shows rough and dense surface morphology. The AC shows different pore sizes and structures depending on the chemical activators used, where AC-KOH shows the largest pore size (165.31 μm). The existence of micropores can be observed in all the activated carbon samples. For the adsorption of Cu2+, all samples show more than 99 % of the removal efficiency. While for photocatalytic testing, the Ag2S-H3PO4 sample shows the highest degradation rate (97.7 %) of MB solutions.

Hydrodynamic Jet Cavitation to Process Natural Graphite for Ultra-Fast Charging Lfp // Graphite Pouch Cells

Graphite has proven to be the most dominant anode material for Li-ion batteries (LIBs) due to its relatively high gravimetric capacity (372 mAh g-1), high Li-ion diffusion coefficient (~10-11 cm2 s-1) andlow delithiation potential (0.1V vs. Li/Li+). (1) Current methods of producing battery-grade graphite are both energy and greenhouse gas intensive. (2) New methods of processing graphite with far lower carbon footprints are becoming available using hydrodynamic jet cavitation. (3) This work tests the Li ion battery anode performance of three different jet cavitation processed graphite powders that have been processed by the above-mentioned method. The materials both matched the performance of commercial synthetic graphite anodes in low C-rate cycling and showed an improved capacity of >100 mAhg-1 LFP in full cells at 10C. Additional testing was also performed on single layer pouch cells. It was found that the rougher surface morphology of the jet cavitation processed graphite causes a slightly poorer initial coulombic efficiency but a far greater capacity at high C-rates.

Crosslinked lignin starch copolymer as a sustainable and thermally stable drilling fluid controller

Fluid loss is a well-known challenge of drilling operations. In this work, a novel sustainable starch-lignin-based polymer was synthesized for possible use in drilling fluid applications. The X-ray photoelectron spectroscopy (XPS) analysis confirmed that kraft lignin was crosslinked with starch via ether covalent bonds. The X-ray diffraction (XRD) analysis confirmed the loss of crystallinity in starch and emerging of new amorphous structures in crosslinked starch-lignin (CSL) polymers after crosslinking with lignin. The incorporation of lignin and new covalent ether bonds improved the thermal stability of starch. The CSL had a rougher surface morphology, higher hydrophilicity, and significantly higher water absorption than starch. CSL-2, with its higher lignin content, demonstrated higher hydrophilicity, better water absorption capacity, and thermal stability than CSL-1. The rheology analysis of the CSL-2 polymer suggested that crosslinking starch with lignin would increase G′ more than G" and reduce tan δ of the polymer solution, resulting in more elastic properties and more stability against the angular frequency. Due to its improved swelling, thermal, and rheological properties as compared to native starch, the produced sustainable lignin-starch copolymer could be used as a new viscosity and rheology modifier, such as a fluid loss controller for oil extraction from wells.

Disk harmonics for analysing curved and flat self-affine rough surfaces and the topological reconstruction of open surfaces

When two bodies get into contact, only a small portion of the apparent area is actually involved in producing contact and friction forces because of the surface roughnesses. It is, therefore, crucial to accurately describe the morphology of rough surfaces, for instance, by extracting the fractal dimension and the so-called Hurst exponent, which is a typical signature of rough surfaces. This can be done using harmonic decomposition, which is easy for periodic and nominally flat surfaces since Fourier transforms allow fast and reliable decomposition. Yet, it remains a challenging task in the general curved and non-periodic cases, where more appropriate basis functions must be used. In this work, disk harmonics based on Fourier-Bessel basis functions are employed for decomposing open single-edge genus-0 surfaces (no holes) as a practical and fast alternative to characterise self-affine rough surfaces with the power Fourier-Bessel spectral density. An analytical relationship between the power spectrum density decay and the Hurst exponent is derived through an extension of the Wiener-Khinchin theorem in the special case where surfaces are assumed self-affine and isotropic. Finally, this approach is demonstrated to successfully measure the fractal dimension, Hurst exponent, without introducing typical biases coming from basis functions boundary conditions, surface discretisation or curvature of the surface patches. This work opens the path for contact mechanics studies based on the Fourier-Bessel spectral representation of curved and rough surface morphologies. All implementation details for this method are available under GNU LGPLv3 terms and conditions.

Fabrication, characterization, and 3D printing of high-internal phase Pickering emulsion stabilized by heat-treated copra protein and calcium composite

HCP-Ca nanoparticles were prepared by incorporating varying concentrations of CaCl2 into heated copra protein (HCP). The results showed a positive correlation between Ca2+ concentration and turbidity, indicating greater HCP aggregation with increasing Ca2+ levels. Microscopy analysis revealed that HCP-Ca nanoparticles had a rough surface morphology. Intermolecular forces such as disulfide bonds, hydrophobic interactions, and hydrogen bonds were key in the conformation of HCP aggregates, with calcium ions enhancing stability by forming salt bridges. HCP-Ca nanoparticle-based high internal phase Pickering emulsions (HIPPEs) were also fabricated using homogenization-centrifugation treatment. The nanoparticles showed contact angles of 87.8° to 98.3°, particle sizes between 80.42 and 80.95 nm, and the HIPPEs had zeta potentials ranging from −23 to −39 mV. The addition of Ca2+ enhanced stability by forming salt bridges, reducing particle size, and altering size distributions. Rheological and texture analysis showed that Ca2+ addition significantly improved the viscoelasticity of HCP-Ca nanoparticle-based HIPPEs, as well as increasing hardness and adhesiveness. Optical microscopy and magnetic imaging techniques revealed details about emulsion formation and oil-water distribution in HCP-Ca nanoparticle-based HIPPEs. The excellent printing stability and structural versatility of HCP-Ca nanoparticle-based HIPPEs allowed the formation of complex 3D structures, offering a valuable approach for fabricating processable and editable HIPPEs from waste materials. This paper aims to develop a food-grade copra protein-based Pickering HIPPE and explore differences in fabrication methods, providing new insights into the design of innovative Pickering stabilizers.

Role of dry media in influencing performance during processing by centrifugal superfinishing

ABSTRACT To achieve better surface quality and higher efficient finishing of AISI 52,100 steel cylindrical roller surfaces, a novel dry medium was prepared, which is composed of millimeter-sized adsorptive medium matrix and polishing paste containing micron-sized abrasives. The study utilized centrifugal superfinishing to examine the effects of dry media with various abrasive types, sizes, and polishing paste ratios. The influence of these dry media on the processing performance was comprehensively evaluated, covering parameters including material removal rate, roughness decrease rate constant (K r ), roughness limit (Ra lim ) value, surface morphology, and profile. In addition, the processing mechanism was revealed. This study provides valuable insights into the development and performance regulation of new media for nano-level superfinishing of complex surfaces.

One‐Step Spray‐Deposited CsPbBr3 Thick Films as a Defect‐Tolerant Platform for Solar Module Fabrication

All‐inorganic CsPbBr3 thick films (≈10 μm) are prepared via a one‐step spray‐deposition method on TiO2‐covered fluorine doped tin oxide substrates. After carbon is pasted on top as the electrode without a hole‐transport layer in between, power conversion efficiency of 8.80% and 4.35% is achieved for large‐area solar cells (0.5 cm2) and solar modules (9.5 cm2), respectively. Tolerant to the impurity phases and rough surface morphology, the CsPbBr3 thick films fabricated through such a scalable method may serve as a platform for further construction of colorful photovoltaic cells and X‐ray‐detection devices.

Hydroxyapatite/Chondroitin Sulphate Nanocomposite Infused with Black Seed Oil for Bone Tissue Applications: Physicochemical Characterizations and In Vitro Screening

AbstractMorbidities associated with natural bone have highlighted the need of advanced bioactive implants for the replacement of damaged bone. Known for their beneficial bioactivity and biocompatibility, Nigella sativa seeds (kalonji/black seed) are traditionally used in many medications. This research focuses on the positive impact of black seed extract on the chondroitin sulfate‐based hydroxyapatite nanocomposite for bone tissue regeneration applications. Novel nanocomposites with varied concentrations of black seed extract (0, 1, 2, and 3 wt%) were fabricated through a coprecipitation approach and analyzed for physicochemical and biological applications. The results of X‐ray diffraction and FTIR spectroscopy revealed that the HCSK3 nanocomposite was successfully developed with appreciably strong molecular interactions among their components. HCSK3 nanocomposite exhibits higher rough surface morphology (Ra −1.13 µm and Rz −4.8 µm), uniform particle distribution (average particle size −9.9 nm), and good thermal stability with total weight loss of 13%. It also provides better nucleation sites for apatite formation and protein adsorption stimulating cell attachment, proliferation, and differentiation. Moreover, HCSK3 nanocomposite showed excellent cell viability, higher ARS/ALP activities, better antibacterial property, and nonhemolytic property (below 3%). Thus, it can be concluded that HCSK3 nanocomposite manifested the highest biocompatibility and negligible cell toxicity. Therefore, it can be employed as an ideal bone implant in the bone tissue restoration phenomenon.

The role of BaTiO3 nanoparticles as photocatalysts in the synthesis and characterization of novel fruit dyes is investigated.

In the present work, the photocatalytic activity against the natural dye extracted from the novel fruits has been studied by the BaTiO3 nanoparticles (NPs) under a ultra-violet (UV) light source. The large concentrations of an essential phenolic agent present in this phytochemical extract superimposed with cloths fibers make strong stain and degrade into another form of toxic, which is excluded from the many textiles industries as the colorful waste waters without recycling and removal of that dye pigments have been investigated using both photodegradation and photoluminescence techniques. The entitled nanoparticles (NPs) were prepared using the soft chemical root-modified solvothermal synthesis combo method and exposure to heat treatment such that the annealing process has been done for different temperatures ranging from 100°C to 250°C. As for as concern the characterization, as a start, structural and morphology studies have been reported here that highly crystalline oriented peaks data using powder x-ray diffraction techniques (PXRD) as well as the surface morphology including the size, shape, and mass distribution using the field emission scanning electron microscopy (FESEM) techniques, which purely belong to rutile tetragonal structure of the crystal system and circular and noncircular flakes like rough surface morphology materials respectively. The lattice dissociation constant 'ε' value of the BaTiO3 NPs has determined to be ~2.71 × 10-3 using the Williamson-Hall (W-H plot) analysis of crystallographic data. In the UV visible spectroscopy findings, since the extreme quantum confinement of BaTiO3 nanoflakes/nanodisc, the optical energy bandgap has been estimated to be a range of 1.98 to 2.67 eV (~2.48 eV) found from the Tauc plot analysis, which contributes to the significantly owing to the enhanced photocatalytic efficiency with excellent performance along exciton formation, superoxide ions, and hydroxyl free radicals generations under UV-vis light irradiation resulting in efficient degradation of typical novel fruit organic dye. Photoluminescence spectra observed at room temperature and low temperature have been observed for the BaTiO3 nanoflakes, which exhibit the blue emission due to the crystalline defects such as the appearance of Ba vacancies leads to the conceivable beginning of p-type conductivity and the origination of free exciton emission reveals the direct bandgap transition nature of nanoflakes. RESEARCH HIGHLIGHTS: According to our findings, 89.71% of the natural syzygium cumin is degraded by photocatalysis reaction. As a plausible mechanism for the destruction of natural dyes under solar light, photocatalytic destruction has been proposed. The reaction between these reactive free radical species leads to high efficiency photodegradation with a short decay time. In addition to water treatment and environmental cleaning applications, the excellent performance of this photocatalyst makes it a promising candidate for other applications. Hence, the synthesized BaTiO3 nanoflakes showcase a highly significant advancement towards the development of a textiles dye recycling method.

A Ni-based metal hydroxide-organic framework mesh membrane with ultra-durable underwater superoleophobicity for high-efficient oil/water separation

Recently, MOF-based oil/water separation membranes with superwettability have attracted great attention in the treatment of oily wastewater due to their uniform chemical composition and intrinsic porosity. However, the real separation performance is still limited by broking the metal-ligand bonds of conventional MOF materials in extreme chemical and mechanical environments, such as acidic, alkaline, saline, organic, and abrasion. Herein, we provide a metal hydroxide-organic framework (MHOF) composite mesh membrane for high-efficient oil/water separation by simply growing Ni2(OH)2 clusters onto a polydopamine (PDA)-modified stainless-steel mesh (SSM). Compared with conventional MOF materials, our membrane possesses ultra-durable underwater superoleophobicity by taking advantages of its strong chemical bridging, rich hydrophilic groups, and rough surface morphology, which enables a 1 μL water droplet to spread to 0° contact angle within <100 ms and also obtains an ultra-low underwater oil adhesion force ∼1.9 μN. Separation of both oil/water mixtures and oil-in-water emulsions can be achieved by this Ni-based MHOF mesh membrane with high separation efficiency >99.7 % and large permeate flux >57,000 L m−2 h−1. Furthermore, the Ni2(OH)2@PDA-SSM mesh membrane exhibits excellent anti-oil-fouling, chemical stability and abrasion resistance, which shows a promising candidate for practical applications. This study provides a rational strategy to construct high-performance MHOF membranes for oil/water separation.

Handmade wastepaper conversion into nanourea incorporated carboxymethylcellulose hydrogel as fertilizer release vehicle for augmenting plant growth

The concept of utilizing handmade wastepaper refuse for synthesis of nanocellulose and later converting it into nanourea incorporated carboxymethylcellulose (NU@CMC) hydrogel has been visualized as a sustainable solution to manage solid wastepaper and simultaneously enrich plant growth by providing nanourea. Various characterization techniques like Fourier-transform infrared spectroscopic (FTIR), Field emission scanning electron microscopic (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM) analysis and Brunauer-Emmett-Teller (BET) analysis confirmed that the NU@CMC hydrogel was rich in functional groups, having porous and rough surface morphology. Swelling ratio was found to be 1457% at pH 7 due to the presence of polar group and porous surface of hydrogel. Maximum water holding capacity (54.45%) was obtained at 2 wt% NU@CMC hydrogels, and it retained moisture in the soil for more than 2 weeks. NU@CMC hydrogel was used as a control release vehicle for the release of nanourea for plants at different pH ranges, and results indicated that this process followed the Fickian diffusion mechanism at pH 7 and 46.71% release efficiency was observed in 18 days. Maximum stem length was observed with NU@CMC hydrogels compared to CMC hydrogel and soil. Thus, eco-friendly, versatile NU@CMC hydrogel with 39.8% biodegradability within 32 days establishes its dual promise for water transport under water-limited conditions and as a fertilizer release vehicle for sustainable plant growth.

Optimization of process parameters for preparing AlN nanopowders by combining carbon-containing droplet combustion and carbothermal reduction methods

In this research, AlN nano-powders were prepared by combining carbon-containing droplet combustion (CCDC) and carbothermal reduction (CR) methods. Firstly, Al2O3+C mixed precursor was synthesized by the CCDC method, and then AlN nano-powder was obtained by the carbothermal reduction of this CCDC precursor. The effects of urea and glucose contents, ignition temperature, and combustion atmosphere on precursors and AlN powders were studied in detail. The results showed that with the molar ratio of urea to aluminum nitrate (U/A) of 3, the atomic ratio of carbon to aluminum (C/Al) of 6, and the ignition temperature at 800 °C under air atmosphere, the prepared precursor was composed of hollow and spherical structure particles exhibiting rough and porous surface morphology with high specific surface area (SSA) (41.4 m2/g). AlN nano-powders obtained by the carbothermal reduction of this precursor were found to be consisted of fine particles with the size of 20–30 nm with high SSA of 39.9 m2/g.

Residual stress induced granular bright facets around inclusions in high-strength steels under high-cycle fatigue

Granular bright facets (GBFs) are frequently observed adjacent to inclusions and within fish-eye areas in the fatigue fractures of high-strength steels under very-high-cycle fatigue (VHCF), considered as a characteristic fracture feature of VHCF. Previous understanding on GBF formation emphasizes the occurrence of nanocystallization in microstructure. In this study, however, the same morphology can also be observed under high-cycle fatigue (HCF). GBF, although closer to fatigue crack initiator and experiencing more stress cycles than the peripheral part of fish-eye (PPFE), exhibits rougher surface morphology in the absence of accumulated plastic strain in microstructure, manifesting relieved crack surface wear. This indicates that the traditional theories on GBF formation for VHCF becomes invalid for HCF. The root cause for GBF formation under HCF is analyzed to be the presence of residual stress around inclusions, which reduces the contact pressure of fatigue crack surfaces inducing wear relief. Accordingly, an analytical model capable of predicting GBF thickness with the effects of HCF conditions and steel properties taken into consideration is established. The model yields accurate predictions of GBF thickness with various loading stresses and inclusion diameters, validated by experimental observations. This study provides theoretical guidance for HCF fracture analysis and fatigue life prediction.