Amorphous Transformation Research Articles

Skin-whitening effect of hydroxypropyl-β-cyclodextrin/glabridin inclusion complex loaded on a dual thermo/pH-sensitive hydrogel

As a natural isoflavone compound, glabridin (GLD) has excellent skin-whitening properties, but its biomedical applications are greatly limited due to its poor water solubility and low skin permeability. In the current work, GLD was complexed with hydroxypropyl-β-cyclodextrin (HP-β-CD) to form a GLD/HP-β-CD inclusion complex that would improve the water solubility and skin permeability by changing the physicochemical properties of GLD, including the formation of intermolecular hydrogen bonds and amorphous transformation. The cytotoxicity of GLD/HP-β-CD on HaCaT keratinocytes is lower than that of GLD, while it has a more substantial inhibitory effect on melanin than GLD. Furthermore, a dual thermo- and pH-responsive hydrogel called PCG was established as the carrier of GLD/HP-β-CD. The PCG hydrogel presented a porous structure, biodegradability, and excellent biocompatibility. GLD had a dual thermo- and pH-responsive release behavior from the PCG hydrogel and displayed an accelerated release rate at weakly acidic pH conditions compared to the neutral pH environment. Moreover, GLD/HP-β-CD/PCG hydrogel can significantly inhibit melanin deposition in vivo. Taken together, this study provides a low toxicity and high efficiency new method for the application of GLD in biomedical fields, demonstrating its enormous potential in skin-whitening.

Preparation of starch-based oral fast-disintegrating nanofiber mats for astaxanthin encapsulation and delivery via emulsion electrospinning

Developing green and efficient delivery systems to promote bioavailability of bioactive ingredients is a sustained demand in food industry. In this work, the astaxanthin (AST)-loaded starch-based fast-dissolving nanofibers with core-shell structure were prepared by emulsion electrospinning technique without using any organic solvent. To load water-insoluble AST in hydrophilic octenyl succinic anhydride starch (OSAS)/polyvinyl alcohol (PVA) nanofiber matrices, AST-loaded nanoscale emulsions (212.19 ± 5.63 nm) with high encapsulation efficiency (91.54 ± 0.14 %) were prepared as a precursor for emulsion electrospinning, using OSAS/PVA aggregates as an emulsifier. The core-shell structure of nanofibers was revealed by the Transmission electron microscopy (TEM), with average diameter of 509.58 ± 12.77 nm, and 88.64 ± 0.49 % for AST were effectively encapsulated in core layer. Nanofiber mats exhibited high encapsulation efficiency (85.11 ± 1.53 %) and excellent storage stability over 7 d. Meanwhile, amorphous transformation of AST enabled it possess higher water solubility, bioaccessibility, and antioxidant properties (97.72 ± 2.17 %) than free AST in aqueous system. The results demonstrated that the green, nontoxic, and biodegradable nanofiber mats prepared by emulsion electrospinning successfully realized the encapsulation and delivery of AST, with broad application prospects in the food and pharmaceutical fields.

Molecular dynamics simulation of the influence of nanocutting parameters on microstructure of AISI M2

Molecular dynamics simulation has become the main analysis method of ultra precision machining of various materials. In this research, molecular dynamics method was used to explore the influence of nanocutting parameters on amorphous atoms, atomic coordination numbers, atomic strain and dislocations of AISI M2 workpiece. LAMMPS was used to construct the molecular dynamics model for CBN tool cutting AISI M2. The polycrystalline model of the workpiece contained 12 grains and iron, chromium and tungsten atoms. The polycrystalline model of the tool contained 3 grains and boron and nitrogen atoms. Tersoff, EAM, Morse and L-J potential energy functions were used to characterize the interaction between atoms. The following results were obtained through 8 groups of simulation experiments: (1) Both cutting speed and cutting depth promoted the amorphous transformation of workpiece atoms. (2) Under the extrusion of the tool, atoms with high coordination numbers were produced in the contact area between the tool and the workpiece. (3) The cutting depth was positively correlated with the average strain of workpiece atoms. Large strain atoms mainly occurred in the cutting area and gradually extended into the workpiece. (4) 1/2 < 111> dislocation was the most common dislocation form in nanocutting. This research plays a rich role in molecular dynamics simulation of nanocutting polycrystalline alloys.

Study on crystal and amorphous transformation of ultrasonic vibration assisted laser cladded Fe-based amorphous coatings

In order to investigate the influence of ultrasonic vibration (UV) on microstructural evaluation of amorphous coating, the Fe-based amorphous (Fe41.5Co12.2Cr7.4Mo37.3C0.3B0.5Y0.4Al0.4) coatings with and without UV were fabricated by laser cladding technology. The microstructure and corrosion resistance of the coatings were studied in detail to understand the mechanism of the UV on amorphous coatings. It can be found that the cavitation effect generated by UV refines and breaks the columnar crystals at the interface. Compared to the coatings without UV, the average length of columnar crystals of coatings with UV decreases by 57.52 %, reducing from 25.26 ± 5.89 μm to 10.73 ± 3.91 μm. In addition, the sound pressure gradient drives the accelerated flow of the molten pool, resulting in a flow velocity of up to 0.134 m/s. The acoustic streaming effect of UV promotes the uniform distribution of elements and inhibits the segregation of the intermetallic compounds, which increases the amorphous content from 68.5 % to 75.3 %. The acoustic streaming and cavitation effects refine the microstructure and increase the amorphous content by using of UV, which contributes to improve the corrosion resistance.

Understanding the machining mechanism in ultrasonic vibration-assisted nanogrinding of GaN

As a typical difficult-to-machine material, gallium nitride (GaN) crystals have the merits of excellent chemical stability and large bandwidth, which can be used in fields of space optical components, photoelectric devices, and electronic communication. The smooth surface of GaN is the basis of these applications. Grinding of GaN has thus drawn increasing attention. Furthermore, vibration-assisted nanogrinding has the potential to reduce grinding forces compared with conventional nanogrinding. In this study, ultrasonic-vibration-assisted nanogrinding of GaN with a single grit is conducted based on molecular dynamic (MD) simulations. The plastic deformation mechanism of GaN single crystals as well as the influence of grinding parameters, such as vibration period and amplitude, on the grinding outcomes are investigated. The MD simulations reveal that plastic deformation of GaN in the vibration-assisted nanogrinding process is dominated by amorphous transformation, dislocation, stacking faults, lattice distortion, and formation of nanocrystals. Furthermore, amorphous GaN atoms are mainly induced in front of the grit and at either side of the grinded groove. In the grinding process, the periodic fluctuation of grinding force components, which include the normal, tangential, and horizontal forces, are stable. A smaller grinding force is obtained when grinding with a small vibration period. Moreover, a small vibration period and large vibration amplitude lead to improved grinding efficiency, suppressing the grinding force and subsurface damage, and improving the grinding quality. The findings in this study facilitate an understanding of the plastic deformation mechanism of GaN single crystals and also provide guidance for parameter optimization during vibration-assisted nanogrinding.

Improving Water Solubility and Skin Penetration of Ursolic Acid through a Nanofiber Process to Achieve Better In Vitro Anti-Breast Cancer Activity.

Woman's breast cancer has always been among the top ten causes of cancer death, and nearly 2% to 5% of locally advanced breast cancers develop a fungating breast wound. Fungal breast cancer leads to skin ulcers, wound ruptures, and other bacterial infections in patients. Ursolic acid (UA), a natural pentacyclic triterpene compound, is widely distributed in many fruits. Previous studies demonstrated that UA has anti-breast cancer, antifungal, and improved wound-healing effects. UA, however, had poor water solubility and low bioavailability, restricting its clinical application. Nanofibers have the advantages of rapid dissolution, improved stability, and bioavailability of active ingredients. We had successfully prepared ursolic acid nanofibers (UANFs) and effectively improved their water solubility and skin penetration. UANFs can increase water solubility by improving the physicochemical properties, including increased surface area, intermolecular bonding with excipients, and amorphous transformation. Furthermore, UANFs had better anti-breast cancer activity than raw UA. UANFs inhibited the expression of phospho-signal transducer and activator of transcription 3 (STAT3) and phospho-extracellular regulated protein kinases (ERK)1/2, and induced cleaved caspase-3 protein expression, but had no effect on the raw UA treatment. In summary, UANFs enhanced the skin absorption of UA and improved its anti-breast cancer efficacy. We expect that UANFs can be used as an anti-breast cancer treatment and reduce the discomfort of breast cancer patients during dressing changes, but more detailed efficacy and safety trials still need to be conducted in further studies.

Nanostructured Molecular-Network Arsenoselenides from the Border of a Glass-Forming Region: A Disproportionality Analysis Using Complementary Characterization Probes.

Binary AsxSe100-x alloys from the border of a glass-forming region (65 < x < 70) subjected to nanomilling in dry and dry-wet modes are characterized by the XRPD, micro-Raman scattering (micro-RS) and revised positron annihilation lifetime (PAL) methods complemented by a disproportionality analysis using the quantum-chemical cluster modeling approach. These alloys are examined with respect to tetra-arsenic biselenide As4Se2 stoichiometry, realized in glassy g-As65Se35, glassy-crystalline g/c-As67Se33 and glassy-crystalline g/c-As70Se30. From the XRPD results, the number of rhombohedral As and cubic arsenolite As2O3 phases in As-Se alloys increases after nanomilling, especially in the wet mode realized in a PVP water solution. Nanomilling-driven amorphization and reamorphization transformations in these alloys are identified by an analysis of diffuse peak halos in their XRPD patterning, showing the interplay between the levels of a medium-range structure (disruption of the intermediate-range ordering at the cost of an extended-range one). From the micro-RS spectroscopy results, these alloys are stabilized by molecular thioarsenides As4Sen (n = 3, 4), regardless of their phase composition, remnants of thioarsenide molecules destructed under nanomilling being reincorporated into a glass network undergoing a polyamorphic transition. From the PAL spectroscopy results, volumetric changes in the wet-milled alloys with respect to the dry-milled ones are identified as resulting from a direct conversion of the bound positron-electron (Ps, positronium) states in the positron traps. Ps-hosting holes in the PVP medium appear instead of positron traps, with ~0.36-0.38 ns lifetimes ascribed to multivacancies in the As-Se matrix. The superposition of PAL spectrum peaks and tails for pelletized PVP, unmilled, dry-milled, and dry-wet-milled As-Se samples shows a spectacular smoothly decaying trend. The microstructure scenarios of the spontaneous (under quenching) and activated (under nanomilling) decomposition of principal network clusters in As4Se2-bearing arsenoselenides are recognized. Over-constrained As6·(2/3) ring-like network clusters acting as pre-cursors of the rhombohedral As phase are the main products of this decomposition. Two spontaneous processes for creating thioarsenides with crystalline counterparts explain the location of the glass-forming border in an As-Se system near the As4Se2 composition, while an activated decomposition process for creating layered As2Se3 structures is responsible for the nanomilling-driven molecular-to-network transition.

In-depth insights into transformation mechanism of synthetic saponite to amorphous silica under acid attack

Amorphous mesoporous materials derived from synthetic saponite (Sap) by acid treatment have been used in catalysis for several decades. Uncovering the transformation process of Sap from layered to amorphous structure under acid attack is beneficial to optimize the structure of Sap-derived mesoporous materials, yet such transformation process remains unclear. Herein, a magnesium-Sap was synthesized by hydrothermal method and then treated with sulfuric acid. By studying the changes in phase composition, morphology, chemical state of elements and surface area of the synthetic Sap after acid attack, a specified transformation mechanism of synthetic Sap to amorphous silica is clarified. The experimental results indicate that after leaching of Mg and Al cations from the Mg/AlO6 octahedral sheets of Sap during acid attack, the retained SiO4 tetrahedral sheets of Sap were transformed into amorphous short-range ordered silica phases and nanoscrolls with pseudohexagonal side pores. The transformation process of synthetic Sap under acid attack can be divided into leaching of metal ions from octahedral sheets of Sap to form layered silica particles, splitting and crimping of surface nano-silica layers from the formed silica particles, and completely amorphous transformation. The distortion of SiO bonds in SiO4 tetrahedral sheets during acid attack might be the driving force for such transformation. This work provides specific transformation process of synthetic Sap under acid attack which is conductive to the controllable preparation of acid-treated Sap derivates, and has certain significance for understanding of structural transformation of clay minerals with MgO6 octahedral structure.

Crack propagation effects on the critical temperature degradation of superconducting Nb3Sn single crystal

The irreversible degradation of Nb3Sn critical performance caused by the crack propagation brings challenges to the reliability of Nb3Sn service equipment. In this paper, the crack propagation behavior of Nb3Sn single crystal was studied by molecular dynamics method. The results show that amorphous transformation occur in Nb3Sn samples with cracks under the applied loading conditions. On the basis of these results, the electronic structures of different regions in the cracked sample are studied by first principles method. The critical temperature response in this process is analyzed in combination with our proposed trans-scale electromechanical coupling model. The physical mechanism behind the critical temperature degradation caused by the transition between the cracked surface and the amorphous zone at the crack tip is discussed. Amorphous states and the crack surface destroy the special kind of bonding in the atom chain direction, inducing the electronic band structure distortions. The density of states curve of Nb3Sn no longer exhibits the characteristic peaks near the Fermi surface observed in cubic crystalline Nb3Sn. The intrinsic relationship between the crack propagation, the electronic structure evolution driven by the local atomic rearrangements, and the irreversible critical temperature degradation of cracked Nb3Sn is revealed by the given model. The results deepen the understanding of the electromechanical coupling behavior of Nb3Sn under complex deformation.

Osteopontin stabilization and collagen containment slows amorphous calcium phosphate transformation during human aortic valve leaflet calcification

Calcification of aortic valve leaflets is a growing mortality threat for the 18 million human lives claimed globally each year by heart disease. Extensive research has focused on the cellular and molecular pathophysiology associated with calcification, yet the detailed composition, structure, distribution and etiological history of mineral deposition remains unknown. Here transdisciplinary geology, biology and medicine (GeoBioMed) approaches prove that leaflet calcification is driven by amorphous calcium phosphate (ACP), ACP at the threshold of transformation toward hydroxyapatite (HAP) and cholesterol biomineralization. A paragenetic sequence of events is observed that includes: (1) original formation of unaltered leaflet tissues: (2) individual and coalescing 100’s nm- to 1 μm-scale ACP spherules and cholesterol crystals biomineralizing collagen fibers and smooth muscle cell myofilaments; (3) osteopontin coatings that stabilize ACP and collagen containment of nodules preventing exposure to the solution chemistry and water content of pumping blood, which combine to slow transformation to HAP; (4) mm-scale nodule growth via ACP spherule coalescence, diagenetic incorporation of altered collagen and aggregation with other ACP nodules; and (5) leaflet diastole and systole flexure causing nodules to twist, fold their encasing collagen fibers and increase stiffness. These in vivo mechanisms combine to slow leaflet calcification and establish previously unexplored hypotheses for testing novel drug therapies and clinical interventions as viable alternatives to current reliance on surgical/percutaneous valve implants.

Amorphous Core Distribution Transformer with Improved Efficiency and Low Loss for Power Sector Application

The amorphous transformer (AMTD) is an energy-efficient transformer that minimizes both airborne pollutants and the amount of energy required to create power. This research investigates the use of amorphous material in transformer construction rather than the usual silicon steel core. It outperforms silicon steel in terms of magmatic characteristics. Because of its high resistivity and low thickness, adopting amorphous as a transformer core instead of a traditional transformer can eliminate 70% of transformer no load losses. When deciding which transform to install and use in the electrical network, the total prices of silicon steel and amorphous steel are considered. The total owed cost (TOC) of any specific transformer is calculated by discounting future transformer losses (losses from both load and no load) to present value and leveling them across the transformer's lifetime. The characteristics of amorphous and conventional electrical cold-rolled grain-oriented(CRGO) materials were evaluated. Amorphous metal is a special type of alloy with an irregular molecular arrangement rather than a well-organized crystalline structure. Amorphous metal can be utilized for the transformer core to increase transformer efficiency. The material's increased magnetic characteristics and physical dimensions lead to much lower hysteresis and eddy current losses. Using amorphous metal cores can minimize transformer core loss by more than60 percent. High power-density transformers are in high demand in many applications where weight and available space are severely constrained, such as power electronics. While electromagnetic device weights and sizes normally decrease at higher frequencies, core loss may increase considerably.

Study on crystal to amorphous transition of nickel-based alloy processed by ultra-short pulsed laser shock peening

The main purpose was to investigate the process of crystal to amorphous transition in nickel-based alloy subjected to ultra-short pulsed laser shock peening. A molecular dynamics model of laser shock peened nanopolycrystalline nickel-based alloy was established using LAMMPS. The influence of shock velocity on the amorphous transformation in nickel-based alloy was analyzed. The results indicated that ultra-short pulsed laser shock peening with ultra-high strain rate plastic deformation promoted the increase and accumulation of defect for nickel-based alloy, contributing to the formation of amorphous structures.

Plasma Bombardment-Induced Amorphization of (TiNbZrCr)Nx High-Entropy Alloy Nitride Films

The (TiNbZrCr)Nx high-entropy nitride films (HENFs) were prepared by high-power pulsed magnetron sputtering (HPPMS). The effect of the N2 flow rate (FN) on the HPPMS plasma discharge, film composition, microstructure, residual stress, tribological properties, and corrosion resistance was investigated. Results show that, with the increase in FN, plasma discharge is enhanced. Firstly, the introduced N atoms react with Ti, Nb, Cr, and Zr to form an FCC nitride phase structure. Then, with the increase in plasma bombardment on the deposited film, the HENFs undergo amorphization to form an FCC+ amorphous structure, accompanied by a decrease in grain size and a change in the preferred orientation from (1 1 1) to (2 0 0). The HENFs deposited at FN = 8 sccm show the highest hardness of 27.8 GPa. The HENFs deposited at FN = 12 sccm present the best tribological properties, with a low wear rate of 4.0 × 10−6 mm3N−1m−1. The corrosion resistance of the (TiNbZrCr)Nx HENFs shows a strong correlation with the amorphous phase. The corrosion resistance of the FCC nitride film is the worst, and the corrosion resistance gradually increases with the amorphous transformation of the film. Based on the above results, nanocomposite high-entropy films can be prepared using HPPMS technology and exhibit excellent, comprehensive performance.

Calculation of electromagnetic force and temperature distribution of amorphous transformers in different operating modes by finite element method

The study used the Finite element method (FEM) by ANSYS 3D software to calculate the distribution of electromagnetic force (EMF) and temperature on the high voltage and low voltage windings (HLVWs) of the amorphous steel core 3 phase transformer (ASCT) which has a power of 1000kVA –22/0.4kV under different load cases: No load, full load and short circuit (SC). The obtained results show the exact temperature distribution and location where the highest temperature is found on the HLVWs of ASCT. From the analysis of the temperature distribution on the HLVWs, it is shown that when the transformer falls into an SC fault, it causes the greatest EMF and thermodynamic force, causing extremely heavy consequences for the transformers. The obtained results help designers, manufacturers, and operators have the most suitable options to improve strength of SC and increase the life of the transformer.

Grain size-dependent mechanical response of metal nitride coating under nanoindentation and its sand erosion performance

In this paper, TiN coatings with grain sizes of 54.8 nm, 68.8 nm, 91.5 nm and 136.9 nm was prepared on the aluminum alloy by extending the coating deposition duration. The mechanical performance under nanoindentation and sand erosion were evaluated. The results show that there is a positive correlation between the hardness of the TiN coating and the grain size. Under the shear stress, the primary mechanism governing the mechanical behavior of the TiN coating is grain boundary sliding when the grain size is less than 70 nm. However, when the grain size surpasses 90 nm, the mechanical response shifts towards the emergence of shear bands and lateral cracks. During nanoindentation loading, TiN coatings with different grain size shows amorphous transformation. Sand erosion experiments demonstrate that refining the grain structure enhances the coordination capability of the TiN coating during plastic deformation, leading to a substantial increase in the amount of sand needed to initiate coating cracks. Simultaneously, the augmentation in the quantity of grain boundaries enhances the TiN coating's capacity for coordinating during plastic deformation, ultimately bolstering its resistance to crack propagation and erosion.

Concentration-Driven Interfacial Amorphization toward Highly Stable and High-Rate Zn Metal Batteries.

The interfacial structure holds great promise in suppressing dendrite growth and parasitic reactions of zinc metal in aqueous media. Current advancements prioritize novel component fabrication, yet the local crystal structure significantly impacts the interfacial properties. In addition, there is still a critical need for scalable synthesis methods for expediting the commercialization of aqueous zinc metal batteries (AZMBs). Herein, we propose a scalable concentration-controlled method for realizing crystalline to amorphous transformation of the Zn metal interface with exceptional scalability (>1 m2) and processing consistency (>30 trials). Theoretical and experimental analyses highlight the advantages of amorphous ZnO, which exhibits moderate adsorption energy, strong desolvation ability, and hydrophilicity. Employing the amorphous ZnO-coated zinc metal anode (AZO-Zn) significantly enhances the cycling performance, impressively maintaining 1000 cycles at 100 mA cm-2. The prototype AZO-Zn||MnO2@CNT pouch cell demonstrates a capacity of 15.7 mAh and maintains 91% of its highest capacity over 100 cycles, presenting promising avenues for the future commercialization of AZMBs.

Elemental partitioning-mediated crystalline-to-amorphous phase transformation under quasi-static deformation

The transformation induced plasticity phenomenon occurs when one phase transforms to another one during plastic deformation, which is usually diffusionless. Here we present elemental partitioning-mediated crystalline-to-amorphous phase transformation during quasi-static plastic deformation, in an alloy in form of a Cr-Ni-Co (crystalline)/Zr-Ti-Nb-Hf-Ni-Co (amorphous) nanolaminated composite, where the constitute elements of the two phases have large negative mixing enthalpy. Upon plastic deformation, atomic intermixing occurs between adjacent amorphous and crystalline phases due to extensive rearrangement of atoms at the interfaces. The large negative mixing enthalpy among the constituent elements promotes amorphous phase transformation of the original crystalline phase, which shows different composition and short-range-order structure compared with the other amorphous phase. The reduced size of the crystalline phase shortens mean-free-path of dislocations, facilitating strain hardening. The enthalpy-guided alloy design based on crystalline-to-amorphous phase transformation opens up an avenue for the development of crystal-glass composite alloys with ultrahigh strength and large plasticity.

Magnesite formation from nesquehonite slurry at 90 °C using some soluble Mg salts: Eitelite as an atypical transient mineral phase

The production of engineered magnesite (MgCO3) under mild conditions remains an important fundamental challenge in order to store permanently the industrial captured CO2. Because, the magnesite is the more-known-stable carbonate at the Earth surface conditions and it is ready-to-use as profitable construction materials. In the present study, time-resolved Raman spectroscopy experiments have been conducted to characterize magnesite formation from nesquehonite slurry at 90 °C in an ionic carbonate alkaline medium (CO32–/HCO3– close to 1) using four different soluble Mg salts (acetate, sulphate, nitrate and chloride of magnesium). The investigated experimental conditions have revealed that only nesquehonite (MgCO3·3H2O) via un amorphous phase transformation is produced at room temperature. However, magnesite was systematically formed from nesquehonite slurry when temperature increase to 90 °C (heat-ageing step). Here, hydromagnesite (Mg5(CO3)4(OH)2·4H2O) and eitelite (Na2Mg(CO3)2) with long lifetimes were the main characterized transient phases prior to magnesite formation depending of the counterions. Moreover, eitelite rare mineral has not been reported as transient phase during magnesite formation. In summary, the imposed carbonate concentration, carbonate speciation, counterions, competitive divalent cations and pH have played a critical role on the magnesite formation at 90 °C. The discovered experimental mild conditions are promising; however, 2–3 days were required in single Mg system, except when dissolved calcium is added (Ca/Mg≈0.15) in the chloride counterion system; for such case only one hour is required to produce Ca-magnesite and protodolomite at 90 °C, i.e., the production of anhydrous Mg-Ca carbonates phases in very reduced time. In this latter case, the monohydrocalcite (CaCO3·H2O) and the nesquehonite precursors produced at room temperature were rapidly transformed via concurrent dissolution into Ca-magnesite (CaxMg1-xCO3) and protodolomite (Ca0.5Mg0.5CO3). In conclusion, these novel insights are relevant for fundamental (direct monitoring of multi-nucleation events in complex ionic and/or slurries systems) and applied (permanent storage of CO2) research on the formation of anhydrous Mg carbonates (e.g., magnesite and dolomite) debated in the last two centuries.

Computation of electromagnetic forces in the windings of amorphous core transformers

Computation of electromagnetic forces in the windings of amorphous core transformers

A Comparative Analysis of Axial and Radial Forces in Windings of Amorphous Core Transformers

A Comparative Analysis of Axial and Radial Forces in Windings of Amorphous Core Transformers