Needle-like Shape Research Articles

GREEN SYNTHESIS OF MANGANESE OXIDE NPS USING MICROTRICHIA PEROTITII DC PLANT EXTRACT: CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY

This study presents a green approach to synthesizing manganese oxide nanoparticles (NPs) utilizing Microtrichia perotitii DC plant leaf extracts as a chelating agent and manganese oxide (MnO2) as a precursor. The NPs underwent comprehensive characterization through UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. X-ray diffraction patterns indicated the synthesis of MnO NPs with an average crystallite size of 10.12 nm. Scanning electron microscope images depicted a needle-like shape with uniform distribution. Fourier transform infrared spectrophotometer analysis identified the strongest bond at 862.025 cm-1 corresponding to the stretching vibration mode of Mn-O NPs. Thermogravimetric analysis confirmed the thermal stability of the NPs. Furthermore, the synthesized NPs exhibited antimicrobial activity against B. Subtilis with a zone of inhibition measuring 25.625±3.01 mm.

Class B60-B80 cement concretes using crushed gravel from the Kama field

The results of a study of the quality of crushed stone from gravel of fr. 5–20 mm and screening of crushing of fr. 0–5 mm of the Kama field were presented and an analysis of their compliance with the requirements of regulatory documents was carried out. The characteristics of the crushing products were determined: grain composition, content of crushed grains; amount of lamellar (flaky) and needle-like shape, presence of dust-like and clay particles, crushed stone crushability during compression in a cylinder, screening fineness modulus and content of reaction silica in crushed stone and screening. Compositions of high-strength concretes of class B60–B80 were developed, in which fine quartz sand was used to enrich the crushing screening, carbonate mineral powder of MP-1 grade and microsilica (MK-85) as a filler, and polycarboxylate superplasticizer Polyplast PK as a water-reducing additive. Optimal compositions were obtained with the following cement consumption: for concrete B60 with a compression strength of 78 MPa, cement consumption was 466 kg/m3, for class B70 with a strength of 91 MPa – 483 kg/m3 and for B80 with a strength of 104 MPa – 503 kg/m3. At the same time, concrete mixtures were characterized by a cone settlement of 25–27 cm.

Synthesis and characterization of ZnO nanorods via hydrothermal route for wastewater recycling

In this work, highly efficient ZnO nanorods (NRs) were prepared using an easy and costeffective hydrothermal process. The Synthesized ZnO NR have been analyzed for their structure, morphology, and optical characteristics using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier Transform Infrared (FTIR), and ultraviolet-visible (UV-visible) spectroscopy, respectively. Additionally, a test is conducted on the ZnO nanorod's photocatalytic efficiency towards the degradation of certain dyes, Methylene Blue (MB) and Methyl Orange (MO). The FESEM investigation revealed that the ZnO nanostructures show nanorods with varying diameters (needle-like shape) with an estimated size of (10 to 20) µm. According to the XRD examination, the NRs had a hexagonal-shaped wurtzite pattern, exhibiting an average crystallite diameter of about 50 nm. FTIR spectra confirmed that functional groups from the substance being extracted were present in the ZnO NRs. The band-gap value of 3.37 eV was determined through the TAUC plot model from the ultraviolet-visible spectrum data. In the presence of as-synthesized ZnO NRs, the MO dye degraded by 100 percent in 46 minutes, but the MB dye significantly degraded by approximately 100 % in 20 minutes with high degradation rate constants kMO = 0.086 min-1 and kMB = 0.180 min-1, respectively.

Mechano-synthesized wollastonite-forsterite composite coatings on the plasma electrolytic oxidized Ti-6Al-4V alloy for dental implant

This study investigated an innovative approach for dental implant coatings by developing mechano-synthesized wollastonite-forsterite composite coatings (MC) on plasma electrolytic oxidized (PEO) Ti-6Al-4V alloy. The process involved PEO treatment using a pulsed DC power supply in an electrolyte solution of mono-calcium acetate and calcium glycerophosphate, followed by MC with mixed wollastonite (CaSiO3) and forsterite (Mg2SiO4) powders. After MC treatment, FESEM, EDS analysis, cross-section, XPS, Raman analysis, corrosion test, and an in vitro test for biocompatibility were performed. Comprehensive surface characterization revealed that wollastonite particles transformed into smaller needle-like shapes, while forsterite particles became slightly less uniform but retained their spherical shape. Higher wollastonite content resulted in greater pore filling with fine particles, whereas increased forsterite content led to fewer fine particles on the surface. Cross-sectional analysis showed Si concentration inside the pores. Notably, wollastonite-rich samples exhibited superior corrosion resistance and rapid initial apatite formation in simulated body fluid (SBF) studies. In contrast, forsterite-containing samples demonstrated more controlled and sustained bioactivity, forming magnesium-substituted hydroxyapatite over time. The novelty of this work lies in combining the bioactive properties of wollastonite and forsterite with enhanced PEO surface characteristics, resulting in coatings with tailored corrosion resistance and bioactivity profiles suitable for dental implant applications.

The Influence of the Combined Addition of La–Ce Mixed Rare Earths and Sr on the Microstructure and Mechanical Properties of AlSi10MnMg Alloy

This study investigated the effect of adding La–Ce mixed rare earths and Sr on the microstructure and mechanical properties of AlSi10MnMg alloy. The experiment utilized different combinations of modifiers, including single La–Ce rare earths, single Sr, and the combined addition of La–Ce mixed rare earths and Sr. This study compared their effects on grain refinement, the modification of the α-Al phase and eutectic silicon phase, and tensile properties and hardness. The results showed that the combined modification of Sr and mixed rare earth elements significantly refined the grains, optimized the morphology of the α-Al phase and eutectic silicon phase, and improved the overall mechanical properties of the aluminum alloy. Under the combined modification, the addition of 0.02 wt.% Sr and 0.1 wt.% RE (La–Ce mixed rare earths) exhibited the most pronounced refining effect. The secondary dendrite arm spacing (SDAS) was reduced by 59.18%. The eutectic silicon phase transformed from coarse needle-like shapes to fine fibrous or granular forms, with an aspect ratio reduction of 69.39%. Meanwhile, the alloy’s tensile strength and hardness were significantly improved. The tensile strength increased to 240 MPa, achieving an increase of 23.08%; the yield strength increased to 111 MPa, achieving an increase of 18.09%; and the elongation reached 7.3%, achieving an increase of 73.81%. This indicates that the proper addition of Sr and mixed rare earths can significantly optimize the microstructure and enhance the mechanical properties of AlSi10MnMg alloy, providing an effective method for the preparation of high-performance heat-treatment-free aluminum alloys.

Thylakoid-based green preparation of porous microneedles for antibiotic residues detection in food samples

BackgroundAntibiotic residues in food chain have raised concerns regarding their toxicity and involvement in antimicrobial resistance. However, most existing antibiotic biosensors are primarily applicable to liquid food samples. Given the complex matrix characteristics of foods, there is an urgent need for the development of effective antibiotic detection platforms that exhibit high universality and flexibility. Porous microneedles (PMN) are microdevice structures with needle-like shapes and microscale pores throughout their composition, which facilitate rapid sampling. Consequently, the integration of PMN with biosensors holds significant promise for the detection of antibiotic residues in complex food samples. ResultsIn this study, hydrogel-forming PMN are fabricated by leveraging the oxygen-production capacity of thylakoid to generate bubbles and form porous structures. These PMN are then integrated with a fluorescence aptasensor for the quantification of the antibiotic netilmicin. The aptasensor consists of a netilmicin (NET) aptamer with stem loop and hairpin structure, which facilitated the binding of SYBR Green I to produce a fluorescent signal. In the presence of NET, the complete binding between NET and the aptamer results in a reduction of fluorescence intensity, thereby generating a detectable signal change for the detection of NET. Utilizing capillary action accelerate fluid extraction (2.9 times faster than nonporous microneedles) and a large specific surface area (5.1072 m2/g) conducive to aptasensor adsorb, the PMN achieve efficient capture and quantification of antibiotic with limits of detection and quantitation of 5.99 nM and 19.8 nM, respectively. SignificancePorous microneedles with tunable porosity and desirable mechanical properties are successfully fabricated. The integration of PMN with aptasensor enable the efficient detection of netilmicin in fish, milk and river water samples, demonstrating high recovery rates. The PMN represent potential tools for the convenient and rapid detection of antibiotic residues within complex food matrices, thereby enhancing food safety monitoring.

Effect of Crystalline Phase and Facet Nature on the Adsorption of Phosphate Species onto TiO2 Nanoparticles.

The current use of TiO2 nanoparticles raises questions about their impact on our health. Cells interact with these nanoparticles via the phospholipid membrane and, in particular, the phosphate head. This highlights the significance of understanding the interaction between phosphates and nanoparticles possessing distinct crystalline structures, specifically anatase and rutile. It is crucial to determine whether this adsorption varies based on the exposed facet(s). Consequently, various nanoparticles of anatase and rutile TiO2, characterized by well-defined morphologies, were synthesized. In the case of the anatase samples, bipyramids, needles, and cubes were obtained. For the rutile samples, all exhibited a needle-like shape, featuring {110} facets along the long direction of the needles and facets {111} on the upper and lower parts. Phosphate adsorption experiments carried out at pH 2 revealed that the maximum adsorption was relatively consistent across all samples, averaging around 1.5 phosphate·nm-2 in all cases. Experiments using infrared spectroscopy on dried TiO2 powders showed that phosphates were chemisorbed on the surfaces and that the mode of adsorption depended on the crystalline phase and the nature of the facet: the anatase phase favors bidentate adsorption more than the rutile crystalline phase.

Structural elucidation, morphological properties, dielectric properties and their physical interpretation of cerium-substituted cobalt and barium-based M-type hexagonal nano ferrites

This research uses the sol–gel method to look into how adding Co2+ and Ce3+ dopant cations changes the structure, shape, and electrical properties of M-type Ba hexagonal ferrites that have been synthesized. x-ray diffraction (XRD) analysis confirms the successful formation of the targeted hexagonal M-type crystal structure. We observed a reduction in unit cell volume and lattice parameters as the dopant concentration increased, indicating the effective incorporation of dopant ions into the crystal lattice. When the doping process happened, needle-like grain shapes appeared, which could be seen with a field emission scanning electron microscope (FESEM). As the concentration of the dopant increased, the dielectric spectroscopic measurements revealed an increase in the loss tangent (tan δ) from 0.05 to 3.68, and a decrease in the dielectric constant (ε′) from 283 to 3.41. This suggests a reduction in polarization and dielectric permittivity, as well as increased energy dissipation within the material. The electric modulus spectra showed relaxation behaviour that was non-Debye-type, which is another sign that there are complex and multifaceted ways for charges to move. The measurements of relaxation time and AC conductivity showed that the relaxation intervals were not regular and that the conductivity dropped from 2.22*10–4 Ω−1m−1 to 1.4*10–7 Ω−1m−1 as the doping concentration increased. Based on these findings, it seems that the processes of conductivity and dielectric relaxation play a big role in how charges move around in the doped ferrites. We validated complex impedance data obtained through electrochemical impedance spectroscopy (EIS) software against calculated impedance values. The derived grain and grain boundary characteristics also agreed with the observed grain distribution and boundaries from the micrographs, further corroborating the analysis.

Investigation of structure, morphology, and corrosion behavior of carboxylic acids/hydroxyapatite/chitosan coatings on Ti discs for implants

Titanium (Ti) and its alloys are widely used in bone defect repair owing to their advantages, including high strength, corrosion resistance, and biocompatibility. The formation of a stable oxide layer on Ti implants enhances the osseointegration process. Nevertheless, additional progress is required to improve the incorporation of these implants at the microscopic and nanoscopic levels to achieve a biocompatible interface. The main objective of this study was to enhance the morphology of hydroxyapatite and the corrosion resistance of Ti implants by applying hydroxyapatite/chitosan (HA/Cs) nanocomposite coatings embedded with carboxylic acids. The coatings were fabricated by electrodeposition, wherein various acid concentrations (acrylic and acetic acids) were employed as Cs electrolyte solvents to enhance the adhesion and bond strength with the titanium metal substrate. The microstructures of the HA/Cs coatings were analyzed using X-ray diffraction. The results demonstrated that the structure of HA was affected by the type of acid used and its concentration as the crystallinity increased with a high concentration of acrylic acid. Additionally, the morphology of HA/Cs was analyzed using a transmission electron microscope. The results showed that the morphology of HA/Cs changed from a hexagonal rod-like shape with acrylic acid samples into a needle-like shape in acetic acid samples. The corrosion behavior was investigated using electrochemical impedance spectroscopy (EIS) in a simulated body fluid (SBF) at 37±2ºC. The EIS results showed a high corrosion resistance with phase angles close to −80° and high impedance values of 80.5 kΩ cm2 with a high concentration of acrylic acid. These results indicated the formation of a highly adhesive and stable film on the implants in the test solution. In conclusion, based on this study and our previous work, the corrosion resistance, good biocompatibility, and biomineralization properties of the prepared HA/Cs-coated Ti recommend it as an alternative implant for clinical applications.

Study on the effect of wax on hydrate formation in the presence/absence of span 80

Scholars have been unable to arrive at a consistent verdict on the effect of wax on hydrate nucleation, as the influence of emulsifiers on the dispersion of wax in oil has been neglected. Accordingly, we discuss the effects of wax, span 80, and their coupling on hydrate nucleation utilizing CO2 as the hydrate guest molecule to clarify the precise role of wax on hydrate nucleation. It was discovered that the incorporation of either 10 wt% wax or 2 vol% span 80 prolonged the induction period, and their combined addition led to a longer induction period. This phenomenon indicates that wax and span 80 negatively impact on hydrate nucleation, and their combination strengthens this process. A combination of macroscopic and microscopic techniques was employed to illustrate the mechanism underlying the effect of wax on hydrate nucleation. The study found that both wax and span 80, as well as their coupling, facilitated the dispersion of water droplets in the oil. However, the waxes alone had a needle-like shape and could not entirely encase the water droplets, resulting in the aggregation of hydrate particles. While span 80 changes the shape of the wax, the coupling effect completely encapsulates the water droplets, preventing gas mass transfer and inhibiting hydrate nucleation. Furthermore, the wax stabilizes the structure of the span 80-containing emulsion, thus enhancing the anti-aggregation of span 80.

Effects of Fe content on the 3D morphology of Fe-rich phases and mechanical properties of cast Al-Mg-Si alloy

Fe is a common impurity element in recycled aluminum scraps, and adjusting Fe content can effectively promote the effective utilization of recycled aluminum. In this study, Al-Mg-Si-Mn-Fe alloys with different Fe contents were prepared by adding various percentage of aluminum scraps. Synchrotron X-ray tomography technology was used to study the morphological evolution of Fe-rich phases and corresponding effect on mechanical properties of studied alloys. The results showed that as the Fe content increased, the 3D morphology of Fe-rich phases changed from fine Chinese-script and needle-like shapes to coarse Chinese-script structure. Their 3D morphology was mainly composed of thin platelets and curved branches. The increase in Fe content did not significantly change the 3D structure of Fe-rich phases, but increased the volume fraction of large Fe-rich phases. When the Fe content reached 0.35 %, the maximum volume and the number of branches of individual phases increased by 182.9 % and 142.2 %, respectively, compared with the 0.2Fe alloy. With the increase of Fe content, the ductility of alloys gradually decreased, especially when the Fe content exceeded 0.25 %. The Fe content had a small effect on the liquidus temperature of alloys, but it changed the initial formation temperature and type of Fe-rich phases. When the Fe content exceeded 0.32 %, it promoted the formation of β-Fe phase, which may be the main reason for the significant decrease in ductility of studied alloys with higher Fe content.

Adaptation of a heat-treatment condition to a precipitation-hardened nickel-based superalloy produced by laser powder bed fusion

This study evaluated the microstructural evolution and mechanical properties of a novel printable nickel-based superalloy subjected to a solution aging treatment. The microstructures of the alloys in as-fabricated and solution-treated states were characterized using a combination of electron backscatter diffraction analysis and scanning electron microscopy. The findings indicate that the cellular crystals gradually transitioned into equiaxed grains with increasing solution temperature. The grain orientation shifts from the <001> orientation perpendicular to the building direction to a random orientation. The average grain size increased, the proportion of low-angle grain boundaries (LAGBs) decreased, and the percentage of annealing twin boundaries (TBs) increased from 0.18% in the as-fabricated state to 65.68% at 1230 °C solution treatment (ST). After lower-temperature ST, a large amount of primary γ′ and η phases precipitated in the as-fabricated alloy, with spherical and needle-like shapes, respectively. As the solution temperature increased, the quantity of the primary γ′ phase gradually decreased, and the η phase became relatively more elongated. At 1130 °C ST, both phases dissolved; following aging treatment, γ′ phase precipitated fully. High strength (1493 MPa) was achieved after direct aging treatment, attributed to the combination of cellular structures and numerous LAGBs produced during deposition with the complete precipitation of γ′ phase during aging. This study demonstrated that laser powder bed fusion alloys can achieve excellent mechanical performance through direct aging without needing ST.

Toward understanding the damage behavior during orthogonal cutting of 2.5D C/SiC composite based on multi-scale modeling and high-speed photography

2.5D C/SiC composite has been a critical high temperature material for aerospace filed due to its excellent wear, high temperature and oxidation resistance. Understanding the cutting damage behavior is crucial for achieving the high reliability application. This paper presents an in-depth study on damage behavior and material removal mechanism during orthogonal cutting of 2.5D C/SiC composite based on multi-scale modeling and high-speed photography. A three-dimensional numerical micro-macro multi-scale model is established considering the characteristics of the brittle SiC matrix, the isotropic carbon fiber reinforcement, and the pyrolytic carbon (PyC) layer. The orthogonal cutting experiments of 2.5D C/SiC composite with high-speed photography technology is carried out. The results show that the proposed model can accurately predict the microscopic deformation and fracture of the fiber. Meanwhile, surface fiber spring-back phenomenon is found based on high-speed photography, and its mechanism is first explanation based on the stress evolution analysis of the multi-scale model. In addition, it indicates that the increase of the depth of cut has a significant impact on the chip shape evolution, transitioning from powdery, needle-like, to block-like or strip-like shape. The paper covers some new sights for low-damage cutting of 2.5D C/SiC composite materials.

Boosted visible light dye-decontamination and colossal dielectric constant features of Bi2O3: Role of In, Cu and Li-dopants

This study focused on improving the optical, dielectric properties, and photocatalytic efficiency of Bi2O3, a prominent photocatalyst with challenges like limited visible light absorption and rapid electron-hole pair recombination. Using an adapted sol-gel technique, pure Bi2O3, In, Cu and Li-doped Bi2O3 visible-light-driven photocatalyst were synthesized. X-ray diffraction (XRD) confirmed monoclinic Bi2O3 formation. The inclusion of In, Cu, and Li ions into the Bi2O3 lattice was evidenced by alterations in diffraction peak intensities, lattice parameters, and changes in average crystallite size. Vibrational spectra corroborated the formation of pure α-Bi2O3 with slight shifts in transmittance bands, aligning with the XRD findings. Morphological investigation via scanning electron microscopy (FE-SEM-EDX) confirmed the purity of the synthesized nanocompositions and unveiled that the doping induces distinct morphological changes in Bi2O3 nanoparticles, resulting in increased porosity and formation of round and needle-like shapes (In-doped), coalescence of particles (Cu-doped), and fused agglomerates with altered particle size distribution (Li-doped). Optical analysis demonstrated a red shift in the band gap energy of α-Bi2O3 (initially 2.90 eV), with In, Cu, and Li doping, resulting in band gaps of 2.77 eV, 2.78 eV, and 2.88 eV, respectively, accompanied by high refractive indices exceeding 2.0, rendering them suitable for optical applications. Both Cu and Li doping led to enhanced relative permittivity (εʹ) values, with the Li-doped sample displaying remarkable εʹ values at low frequencies (up to 1000 Hz). The In, Cu and Li doping has the effect of reducing PL (photoluminescence) emission intensity while simultaneously diminishing radiative recombination and promoting the separation of photogenerated charge carriers. The doped samples demonstrated superior degradation performance, with In-doped and Cu-doped samples achieving degradation efficiencies of 99% and 91%, respectively, within 180 min. This remarkable performance can be attributed to their visible-light-responsive band gaps, increased electron-hole trapping sites, and distinct morphological features.

Visible-light responsive BiVO4 nanocompositions: Enhanced photocatalytic, electrical and optical performance through Ni and Ni/Co doping

The pronounced light sensitivity of BiVO4 has garnered significant attention, establishing it as a visible light-responsive photocatalyst. This study was focused on enhancing the optical, dielectric constant properties, and photocatalytic activity of BiVO4 compositions. By employing a modified combustion method, pure BiVO4, Ni-mono-doped (BiNi0.02V0.98VO4), and Ni/Co-bi-doped (BiCo0.02Ni0.02V0.96VO4) were synthesized. X-ray diffraction (XRD) analysis validated the formation of a monoclinic BiVO4 phase. The incorporation of Ni2+ and Co2+ ions into the BiVO4 lattice was supported by variations in the lattice parameters, volume expansion and increased average crystallite size. Morphological investigation via scanning electron microscopy (SEM-EDAX) confirmed the purity of the synthesized nanocompositions and unveiled distinctive rod-like and needle-like particle shapes in BiNi0.02Co0.02V0.96VO4, with an aspect ratio of 0.07–0.1, indicating potential benefits for efficient charge separation in photocatalysis. Optical examination highlighted redshifts in band gap energy (2.36 eV) due to both Ni and (Co, Ni) co-doping, leading to direct band gaps of 2.34 eV and 2.32 eV, respectively. High refractive index values exceeding 2.5, conducive to optical applications, were observed across all samples. Through Ni and Ni/Co doping process, a notable enhancement in conductivity emerged, particularly within the low-frequency domain. The co-doping of Ni and Co demonstrated elevated relative permittivity (εʹ) values exclusively within the low-frequency span, up to 100 Hz. In contrast, the Ni-mono-doping interestingly disclosed an enhancement in (εʹ) across all frequency ranges. Photocatalytic results demonstrated heightened degradation activity in doped samples, with the BiNi0.02Co0.02V0.96VO4, sample exhibiting the highest rate, achieving 88 % degradation efficiency in 180 min. This exceptional performance can be attributed to its visible-light-responsive band gap, increased electron-hole trapping sites, and distinct morphology.

Investigation of enhanced strength anisotropy in an extruded Mg–Al–Ca–Mn alloy at cryogenic temperature

This study systematically compared the microstructural evolution and mechanical behavior of the extruded AXM10304 alloy during tensile deformation along both the extrusion direction (ED) and transverse direction (TD) at cryogenic temperature (CT) and room temperature (RT). The results indicate that the variations in work hardening mechanisms contribute to the observed strength anisotropy in both the ED and TD samples. The yield strength discrepancy between different orientations is ∼88 MPa at RT and ∼179 MPa at CT. It is evident that the alloy exhibits more pronounced strength anisotropy during cryogenic deformation. It is noteworthy that in the CT-ED samples, the ratio of the critical resolved shear stress (CRSS) for pyramidal I and II to that of basal <a> dislocations is relatively minimal, facilitating the activation of more pyramidal dislocations. Cross-slip in CT-ED provides a relatively facile path for dislocation slip, resulting in material softening during straining. The CT-TD sample exhibits the highest work hardening capacity and a consistent dislocation storage rate. Twinning significantly contributes to the hardening observed in the TD samples. This study also illustrates that tailoring twinning morphology to a refined needle-like shape through temperature manipulation can further enhance the work hardening of Mg alloys.

Insights into the effects of Re and Ta on TCP phase evolution in nickel-based SX superalloys: Experimental and simulation analysis

This study explores the effects of Re and Ta interactions on TCP (topologically close-packed) phase precipitation in experimental alloys under long-term thermal exposure. TCP phase is thoroughly examined and analyzed in terms of its location, morphology evolution, structural identification, and phase transition, employing thermodynamic calculations and first-principles analysis. The main findings indicate that the standard heat treatment used in the experiment does not fully eliminate microstructure segregation. Particularly, W and Re exhibit significant segregation in the dendrite region, resulting in preferential TCP phase formation in this region. Re induces destabilization of the γ-matrix and greatly enhances TCP phase precipitation, whereas Ta enhances the supersaturation of the γ-matrix. The interaction between Ta and Re further enhances the precipitation of the TCP phase. Thermodynamic calculations and first-principles analysis indicate that Re significantly improves the driving force of TCP phase precipitation from the γ-matrix, whereas the effect of Ta is found to be slight. Under thermal exposure at 900 °C, the σ-phase is firstly observed in the 8Ta2Re alloy, exhibiting a long needle-like shape, followed by subsequent evolutions resulting in the transition to the P-phase. The phase transition from the σ-phase to the P-phase is governed by the diffusion of elements, with Ni playing a crucial role in continuous diffusion.

Strain-induced precipitation behaviors of 7Mo super-austenitic stainless steel

Strain-induced precipitation (SIP) behaviors of 7Mo super-austenitic stainless steel (SASS) were studied by strain relaxation test at 850 °C. Our results reveal that sigma (σ) phases are the predominant SIP of 7Mo SASS, with the chemical formula of (FeNi) (CrMo). SIP first precipitates in granular shape at HAGBs, such as deformed grain boundaries (SIP-GBs), interfaces between deformation twin layers and matrix (SIP-TW), and HAGBs inside deformed grains (SIP-HAGBs). This is attributed to the ability of HAGBs for providing high deformation stored energy, nucleation sites, and efficient element diffusion channels. When the nucleation sites at HAGBs become saturated with increasing holding time, needle-like SIPs (SIP-NL) are precipitated along closely packed planes of γ-Fe matrix. The specific orientation relationships between SIP-NL and matrix, namely (−111)γ-Fe//(00–1)σ, [0–11]γ-Fe//[-110]σ or (-1-1-1)γ-Fe//(00–1)σ, [0–11]γ-Fe//[-110]σ, and the needle-like shape are contribute to minimizing interfacial energy and elastic strain energy of SIP, respectively, thereby promoting SIP-NL. The absence of SIP on dislocations can be attributed to the large critical nucleus size of σ phase (about 4.87 nm), which poses challenges for SIP nucleation through dislocation distortion energy. Mo is the controlling element for the nucleation and growth of SIP. SIP can promote cDRX through particle-induced nucleation (PSN) mechanism during the deformation process, while residual high-density dislocations around SIP can also promote cSRX during the holding process. During holding process, the boundaries of recrystallized grains can also serve as nucleation sites for SIP, thereby promoting SIP, and finally form a multi-layer structure of “σ phase/Recrystallization/σ phase”.

Membrane crystallization for recovery of lithium carbonate crystals: Study on process parameters and salts effect for Li2CO3-NaCl-KCl-LiCl solutions

In this work, membrane crystallization (MCr) process was employed for recovery of lithium carbonate (Li2CO3) crystals from synthetic brine solutions. First, the effect of the main operating conditions in MCr, including feed temperature (40, 50, and 60 °C) and flowrate (0.81, 1, and 1.3 L/min) was investigated on the crystallization of Li2CO3 in a binary solution. Next, the effect of main inorganic salts in the brine solutions (i.e., NaCl, KCl, and LiCl) and the mixture of them on the MCr performance and crystallization of Li2CO3 were investigated. In-line microscope, light microscope, scanning electron microscope, and X-ray diffraction test were used to observe the crystallization and characterize the obtained crystals. The obtained results revealed that feed temperature is the main parameter to dominate the nucleation and crystal formation and growth. Thus, the higher the feed temperature, the faster the crystal formation and the larger the crystals. The average crystal size increased from 9.59 to 30.51 μm, when the feed temperature increased from 40 to 60 °C, respectively. However, smaller crystals were observed with adding NaCl and KCl to the solution. Moreover, none of the operating parameters nor the salts additives did affect the crystals shape and the obtained Li2CO3 crystals possess needle-like shape.

Mineralized Microgels via Electrohydrodynamic Atomization: Optimization and In Vitro Model for Dentin-Pulp Complex.

There is growing interest in the use of micro-sized hydrogels, including bioactive signals, as efficient platforms for tissue regeneration because they are able to mimic cell niche structure and selected functionalities. Herein, it is proposed to optimize bioactive composite microgels via electrohydrodynamic atomization (EHDA) to regenerate the dentin-pulp complex. The addition of disodium phosphate (Na2HPO4) salts as mineral precursors triggered an in situ reaction with divalent ions in solution, thus promoting the encapsulation of different amounts of apatite-like phases. Morphological analysis via image analysis of optical images confirmed a narrow distribution of perfectly rounded particles, with an average diameter ranging from 223 ± 18 μm to 502 ± 64 μm as a function of mineral content and process parameters used. FTIR, TEM, and EDAX analyses confirmed the formation of calcium phosphates with a characteristic Ca/P ratio close to 1.67 and a needle-like crystal shape. In vitro studies-using dental pulp stem cells (DPSCs) in crown sections of natural teeth slices-showed an increase in cell viability until 14 days, recording a decay of proliferation at 21 days, independent on the mineral amount, suggesting that differentiation is started, as confirmed by the increase of ALP activity at 14 days. In this view, mineralized microgels could be successfully used to support in vitro osteogenesis, working as an interesting model to study dental tissue regeneration.