Supersaturation Research Articles

Preparation of nanosized liquid-like clusters of irinotecan hydrochloride trihydrate for injection concentrate to reduce carbon footprint

The surprisingly stable irinotecan hydrochloride trihydrate injection concentrate having a supersaturated concentration of 20 mg/mL at 25 °C was due to the frustration of 150 nm sized liquid-like nanosized clusters formed by the aggregation of dimers of 1.5 nm in an aqueous phase, evidenced by the non-linearity of van’t Hoff plot and dynamic light scattering measurement. The adoption of this stable supersaturated solution at 20 mg/mL by manufacturers as the commercial concentration was beneficial due to the less volume being involved throughout the manufacturing, handling, storage and transportation of the commercial product, while also enabling a versatile on-site concentration adjustment by dilution prior to intravenous administration. Regarding the physical characteristic of the solid state of irinotecan hydrochloride trihydrate, it was found to exist as a channel hydrate as evidenced by single-crystal, and high-temperature X-ray diffraction experiments. Dehydration takes place at approximately 35 °C as demonstrated by thermogravimetric analysis. Because of its non-stoichiometric nature under various RH values revealed by dynamic vapor sorption, the irinotecan hydrate salt raw material must be kept at 25 °C or below, and under the relative humidity of 40 % to 60 % to maintain the original stoichiometric ratio of the raw material.

STRUCTURE AND MECHANICAL PROPERTIES OF DEFORMED Mg-Sm-Tb-Zr ALLOYS

The structure, aging kinetics and mechanical properties of alloys of the new Mg-Sm-Tb-Zr system with different content and ratio of rare-earth metals obtained by hot pressing have been studied. A different effect of samarium and terbium on the process of recrystallization during deformation and the nature of hardening of alloys during additional aging depending on its duration as a result of the decomposition of a supersaturated magnesium-based solution has been established. The mechanical properties of the alloys after hot pressing and aging, including heating in the temperature range up to 300 °C, have been determined.

Stabilities of substitutional solutes in α-iron under uniaxial strain

Nonuniform strain fields in ferritic/martensitic steels working in extreme conditions might induce segregation of alloying solutes. We optimized the structures of iron alloy systems under uniaxial tensile strains along [001] direction within density-functional theory. The calculated segregation energies of solutes Ni, Cu, Al, and Si decrease drastically in a linear fashion as the tensile strain increases up to 17.5%, while those of Co and Ti only change slightly. The segregation energies of solutes V, Nb, Ta, Cr, Mo, and W first decrease and then increase. These results might indicate that, for all solutes studied except Co and Ti, segregation behaviors happen in ferritic/martensitic steels under tensile strains. The shape deformation effect plays a major role in the segregation energies of solutes Cu, Al, Si, Ni, Nb, Ta, Cr, and Mo, while the volumetric effect is dominant for solutes V and W. The segregation energy changes owing to the tensile strain increase from 8% to 14% exhibit a linear relation with the Young modulus changes of the alloys relative to α-iron, which indicates a correlation between the stabilities of solutes and their bonding strength with iron neighbors. The linearly decreasing mixing energies of solutes Mg, Zn and Ga in α-iron with increasing uniaxial strain might suggest a new possible way of fabricating supersaturated iron solid solutions.

FORMATION AND DECOMPOSITION OF ANOMALOUS SUPERSATURATED MOLYBDENUM SOLUTIONS IN COPPER-BASED CONDENSATES


 Cu-Mo condensates in the concentration range of the latter from 0.3 to 1.5 at.%, obtained by simultaneous evaporation in vacuum with subsequent condensation of the resulting vapor mixture on a non-orienting substrate (PVD method), were studied. The components of this system do not form chemical compounds under equilibrium conditions and are mutually insoluble in liquid and solid states. The structure of Cu-Mo condensates was studied by transmission electron microscopy and X-ray diffractometry both in the derivative state and after a series of isothermal anneals in the temperature range from 300 to 900°C. It was found that small concentrations of molybdenum lead to significant dispersion of the matrix metal. Molybdenum tends to form segregations at the boundaries of copper grains and form a strong coherent bond with the matrix metal, which persists even after isothermal annealing. The conditions for the formation of an anomalous supersaturated solid solution of molybdenum in the copper matrix, as well as the conditions for its decomposition, have been revealed. An assumption is made about the mechanism of formation of such a solution during condensation from the vapor phase, which consists in the kinetic capture of molybdenum atoms by the crystallization front during condensation from the vapor phase. It was found that the decomposition of the supersaturated solid solution begins when heated to 0.5 of the melting point of copper and is accompanied by a dispersion solidification process. During the experiment, it was first recorded that the dispersion solidification process can have a two-stage character. The first peak is observed in the region of 30 minutes of annealing, and the second peak is observed after about 2 hours of isothermal annealing. The height of the dispersion hardening peaks increases with increasing molybdenum concentration. It is suggested that the appearance of the second peak of dispersion hardening is associated with the peculiarities of the interaction between copper grains and molybdenum segregations at the grain boundaries. It is shown that the structure after solution decomposition is typically composite. The advantage of this material over conventional dispersively hardening alloys is the fact that in these pseudo-alloys there is no reverse solution of hardening particles at an increase in temperature.

Effect of Samarium on the Properties of Hot-Extruded Mg–Y–Gd–Zr Alloys

The effect of such an additional promising alloying element as samarium on hot-extruded Mg–Y–Gd–Zr alloys is investigated. The microstructure, kinetics of aging during the decomposition of a supersaturated Mg solid solution, and the mechanical properties of the alloys are studied. The differences of the recrystallization processes that occur in hot-extruded alloys with various contents of samarium (0, 1.7, 2.5%) are demonstrated. After hot extrusion, Mg–Y–Gd–Zr and Mg–Y–Gd–Sm–Zr alloys are additionally hardened during aging due to the decomposition of a supersaturated Mg solid solution. At the same time, samarium changes the nature of this hardening. The alloys with samarium are hardened faster, and the maximum hardness is achieved with shorter aging exposures. The mechanical properties of hot-extruded Mg–Y–Gd–Zr alloys with samarium addition are determined at room and elevated up to 300 °C temperatures. The efficiency and expediency of using samarium both as a separate alloying element and as a partial replacement of more expensive rare-earth elements in alloys with yttrium and gadolinium are shown.

Novel High‐Pressure Potassium Chloride Monohydrate and Its Implications for Water‐Rich Planetary Bodies

AbstractSaline water is a common fluid on the Earth‘s surface and in ice planets. Potassium chloride (KCl) is a common salt and is expected to be a ubiquitous solute in salt water in the Universe; however, few studies investigated the behavior of KCl‐H2O system at high pressures and temperatures. In this study, powder and single‐crystal X‐ray diffraction (SC‐XRD), Raman and Brillouin scattering combined with diamond anvil cells were used to investigate the phase relation in the KCl‐H2O system for different KCl concentrations at 0–4 GPa and 298–405 K. The results of powder X‐ray diffraction and Raman scattering demonstrate that a novel KCl hydrate is formed when KCl aqueous solutions transform to solid ice‐VI and ice‐VII at high pressure. Simultaneously, the single‐crystal of KCl hydrate is synthesized from a supersaturated KCl solution at 298 K and 1.8 GPa. The structure is solved by SC‐XRD, indicating a KCl monohydrate with the P21/n space group is formed. We have verified the phase stability of KCl monohydrate by using Raman spectroscopy and density functional theory. Our results indicate that KCl monohydrate is a stable phase under pressure and temperature conditions between 1.6 and 2.4 GPa and 298–359 K. By considering the thermal profile and composition of icy moons, we hypothesize that the formation and decomposition of KCl monohydrate might induce mantle convection in these moons.

Structure and Electrical Properties of AlFe Matrix Composites with Graphene

Composites based on Al-Fe alloys and reinforced with three-layer graphene sheets were synthesized “in situ” under a layer of molten salts. Composites containing 0.12 wt.% graphene were subjected to severe plastic deformation via high-pressure torsion. SEM and TEM were used to study the morphological and size characteristics of the composite structure in the as-cast and deformed states. Herein, it is shown that severe plastic deformation leads to the deformation-induced dissolution of iron-containing aluminides with the formation of a supersaturated Al solid solution with a submicrocrystalline structure. The hardness and electrical properties of the graphene composites were measured in different structural states and compared to the characteristics of the matrix alloy.

Mechanisms related to the influence of natural aging on the precipitation behavior of the A357 aluminum alloy during artificial aging

This study investigated the influence of natural aging (NA) on the precipitation behavior of the main precipitate β″ and hardness evolution during the subsequent artificial aging (AA) process of the precipitation strengthened A357 aluminum alloy. The corresponding mechanisms were analyzed. The results demonstrate that natural aging has adverse influence on the precipitation process during artificial aging. The underlying mechanism is that small GP zones are formed during natural aging but cannot become nucleation sites for the β″ phase during artificial aging, which spontaneously consumes the supersaturated solute atoms in the Al matrix, increases the nucleation barrier of the β″ phase, and also consumes the vacancies produced after solid solution and quenching, thereby reducing the nucleation rate of the β″ phase during artificial aging, and leading to an un-expected increase in the size of the precipitated phase, thus reducing the peak aging hardness of the alloy. This effect becomes more pronounced with increasing natural aging time. Increasing the artificial aging temperature can improve the nucleation rate of the β″ phase during artificial aging, thereby to some extent reducing the unfavorable influence of natural aging on the artificial aging by reducing the sizes and increasing the amount of the β″ precipitates.

Study of supersaturated solid solution decomposition during quenching of sheets from Al-Mg-Si aluminum alloy

This paper presents the results of a study of the stability of a supersaturated solid solution (SSS) of sheets made of thermally hardened aluminum alloy of the Al-Mg-Si system with a small addition of copper (Al-0.6Mg-1.0Si-0.2Cu) under various quenching modes. The samples were subjected to isothermal or continuous quenching with different quenching cooling rates, after which artificial aging was carried out at a temperature of 170°C. From the results of thermodynamic modeling of the equilibrium phase composition of the alloy, it was found that for the temperature range from 300 to 530°C, the presence of the β-phase (Mg2Si) is most likely. With the use of transmission electron microscopy and X-ray spectral microanalysis, it was found that during quenching, the decomposition of SSS leads to the precipitation of undesirable large particles of metastable β-type phases or equilibrium β-phase. The nucleation of the secretions is realized in the form of rod-shaped particles by a heterogeneous mechanism mainly on the surface of the α-phase dispersoids (Al15(Mn,Fe)3Si2), which thus significantly increase the quenching sensitivity of the alloy. The formation of these secretions at a low quenching rate causes, during subsequent aging, a decrease in the proportion and density of formation of strengthening particles of the β" phase, and also leads to an increase in their size and heterogeneity of distribution in the aluminum matrix, which reduces the potential of dispersion hardening during aging and corrosion resistance of the material.

Investigation into the Nucleation of the p-Hydroxybenzoic Acid:Glutaric Acid 1:1 Cocrystal from Stoichiometric and Non-Stoichiometric Solutions.

The nucleation in the p-hydroxybenzoic acid:glutaric acid 1:1 cocrystal (PHBA:GLU) system has been investigated in stoichiometric and non-stoichiometric acetonitrile solutions by induction time experiments. Utilizing the ternary phase diagram, the supersaturated non-stoichiometric solutions were created with compositions along the invariant point boundary lines. In all cases, the PHBA:GLU cocrystal was the nucleating phase, even though the non-stoichiometric solutions were also supersaturated with respect to the pure solid phases. The nucleation of the cocrystal from the mixed solutions is found to be more difficult than the nucleation of the pure compounds from the respective pure solutions, as captured by lower pre-exponential factors (A). However, if the driving force is defined per reactant molecule instead of per heterodimer, the cocrystal nucleation difficulty is close to that of the more difficult-to-nucleate pure compound. The difference in nucleation difficulty of the cocrystal from stoichiometric and non-stoichiometric solutions was captured by differences in the interfacial energy, while the pre-exponential factor remained unchanged. Apart from the pure GLU system, the relation between the experimentally determined pre-exponential factors for the different systems correlates with calculated values using theoretical expressions for volume-diffusion and surface-integration control.

Effect of heat treatment on microstructure and mechanical properties for laser powder bed fusion of nickel-based superalloy: A review

Laser powder bed fusion (LPBF) is most widely used method for presenting an innovative manufacturing approach that operates layer by layer. This technique relies on a geometrical model and offers a viable substitute for material processing. The utilization of LPBF for producing nickel alloys has garnered significant interest across various domains due to their exceptional attributes. These attributes include excellent corrosion resistance, favorable mechanical properties, and the quality of the manufactured alloys. The particular solidification conditions arising from the metal fusion in the selective laser fusion process, combined with layer-by-layer deposition, give rise to unique microstructural characteristics. These include the development of supersaturated solid solutions, significant microstructural refinement, and the introduction of residual stresses. As a result, adjustments might be necessary for heat treatment and hot isostatic pressing, practices commonly employed with conventionally manufactured nickel alloys. These adaptations would accommodate the metallurgical nuances specific to Ni alloys produced through direct metal laser deposition, effectively addressing issues arising from the inherent characteristics of the process. This review paper compiles the most recent scientific discoveries concerning thermal treatment applied to additively manufactured nickel alloys using the selective laser sintering process.

Investigation on the preparation, microstructure, mechanical and degradation properties of laser additive manufactured Zn–Li–Mg alloy for bioresorbable application

Zinc (Zn) is a potential bioresorbable metal material (BMM) with a degradation rate lower than magnesium and higher than iron. However, clinical applications of pure Zn are limited due to its poor mechanical properties and localized degrading tendency. Overcoming these drawbacks is made possible by the process of alloying. The Zn-0.6Li-0.5Mg alloy samples were prepared using the laser powder bed fusion (LPBF) process in this work. The innovative technique combining fast solidification produced by LPBF and alloying with Li and Mg was presented to enhance the mechanical properties of Zn in this work. The relative density, microstructure, mechanical properties, and corrosion resistance of LPBF-built Zn-0.6Li-0.5Mg alloy were investigated. According to the results, the LPBF fabricated Zn-0.6Li-0.5Mg alloy with fine equiaxed α-Zn grains were uniformly distributed with precipitated Mg2Zn11 and LiZn4 at grain boundaries. More interestingly, the average grain size of α-Zn was recorded at 7.2 ± 3.2 μm with Li and Mg. Due to the rapid solidification process, Mg dissolved primarily in the Zn matrix and developed a supersaturated solid solution. As a result, with the addition of Li and Mg, the mechanical properties of the Zn matrix increased considerably. When combined, Zn-0.6Li-0.5Mg alloy can be an attractive candidate for bioresorbable medical implants in orthopedic applications.

EBSD-data analysis of an additive manufactured maraging 300 steel submitted to different tempering and aging treatments

Maraging is a high alloy steel sensitive to the precipitation of intermetallics from a supersaturated solid solution during aging heat treatments. The precipitation phenomenon is well described in the literature, which gave rise to the alloy name regarding a martensite matrix with precipitates formed by aging treatment. Many studies have been performed to characterize this material, usually subjected to many sample preparations for transmission microscopy, which is very laborious, and few EBSD analyses. Therefore, in this work, a large study was conducted using electron backscatter diffraction (EBSD) to analyze maraging microstructures through band-contrast, kernel average misorientation (KAM), grain orientation spread (GOS), and misorientation distribution. Our results show that solubilization of the additive manufactured maraging steel resulted in a more homogeneous microstructure with new angle grain boundaries. Furthermore, tempering heat treatments relieve martensite strain, increasing band contrast values. Posterior aging presented a low impact on the results of EBSD analysis.

Metastable aluminum boride: density functional theory study of prerequisites of formation

AbstractAluminum borides have significant practical interest as energetic additives to fuels, explosives and propellants due to their favorable thermodynamic and kinetic characteristics. Density functional theory calculations with periodic boundary conditions have been performed to evaluate the enthalpy of formation of two aluminum borides: the well‐known aluminum diboride AlB2 and the metastable Al1.28B phase, which precedes the formation of AlB2 during heat treatment of mechanically activated composite aluminum‐boron powders, as well as aluminum ion‐implanted with boron. The calculated formation enthalpy of AlB2 is −3.6 kcal/mol, which agrees well with estimates from literature. The enthalpy of formation of Al1.28B, calculated for the first time, is 4.8 ± 0.4 kcal/mol. To understand the prerequisites for the formation of Al1.28B observed in experiments, the enthalpy of formation of supersaturated solid solutions of B in Al has been evaluated. The reasons for the preferential formation of the metastable Al1.28B phase over the thermodynamically stable AlB2 phase are discussed.

Ageing evolution process of the [formula omitted]-phase in Al-Si-Cu-Mg alloys: Atomic-scale observations and first-principles calculations

This work characterizes the high temperature (above 200 °C) ageing process of the θ′ phase in Al-Si-Cu-Mg alloys by using atomic-resolution HAADF-STEM and first-principles calculations. By characterizing the morphology and coarsening growth process of the θP′ and θP1′ precursor, experimental observations suggest that the θP′ phase is based on GPI (Guinier-Preston I) growth expansion. With the ageing time increases and the atomic concentration changes, the Cu atoms on the outside of the θP′ phase rearrange to form the θP1′ phase. Subsequently, the θP2′ precursor phase is formed locally in the θP1′ phase as the Cu atoms gradually enter the θP1′ phase. Besides, it has been observed experimentally that the θP2′ precursor phase can be directly transformed into the θ′ phase without changing the morphology, structure and orientation relationships of the phase. Based on the experimental characterization and theoretical calculations of this work, we have proposed a novel ageing precipitation sequence: SSSS (Super Saturated Solid Solution)→GPI→θP′→θP1′→θP2′→θ′.

EFFECT OF EQUAL CHANNEL ANGULAR PRESSING AND SUBSEQUENT AGING ON THE STRUCTURE AND MECHANICAL PROPERTIES OF Al-Mg2Si ALLOYS WITH TRANSITION METAL ADDITIVES

The effect of equal-channel angular pressing (ECAP) at a temperature of 150°C and subsequent aging on the structure and strength characteristics of Al-Mg2Si alloys alloyed with Sc and combined additives (Sc + Zr) and (Sc + Hf) has been studied. An analysis of the dependences of hardness and electrical resistivity on time and temperature revealed the same nature of the decomposition of a supersaturated solid solution of alloys with additives (Sc + Zr) and (Sc + Hf), and also made it possible to obtain optimal aging conditions for these alloys. The microstructure of the alloys and the precipitation of secondary phases were carefully studied using scanning (SEM) and transmission electron microscopy (TEM). In alloys after ECAP and aging, an increase in both strength and ductility was revealed due to the compensation of aging processes by recovery processes associated with the rearrangement of the dislocation structure.

Revisiting the effect of Ag additions on Ω precipitation and heat resistance of Al–Cu–Mg–Si–Ag alloys

In heat-resistant Al–Cu–Mg–Ag alloys, the presence of AgMg segregation layer on Ω phase ensures its high thermal stability. It was reported Ω precipitation would be inhibited when Si was added such that the Mg/Si mass ratio was lower than 2. However, in this work, it has been proved the notable increase in Ag content from 0.5% to 0.8% could still promote precipitation of Ω besides θ′ in an Al–Cu–Mg–Ag–Si alloy with a Mg/Si mass ratio around 1.7. The key point is to obtain an Ag/Mgexcess atomic ratio greater than 1 under the premise of W(Mg)/W(Si) > 1.4 in the supersaturated solid solution, where Mgexcess denotes the remaining Mg solutes after the formation of C/L phase. Although the fine precipitation of Ω in the 0.8 Ag alloy increases the total volume fraction of precipitates and yield strength, their quick coarsening at high temperature leads to a more pronounced strength loss. Such a comparison reveals the fully enveloped Ω precipitate is less stable than the θ′ precipitate with multiple interface phases. These findings update our knowledge on the systematic composition design for tunning Ω/θ′ precipitates' ratio and properties of Al–Cu–Mg–Ag–Si alloys.

Green biosynthesis of DHA-phospholipids in tailor-made supersaturated DHA aqueous solution and catalytic mechanism study

Docosahexaenoic acid-phospholipids (DHA-PLs) were prepared via lipase-mediated transesterification of DHA donor and phosphatidylcholine (PC) in a purely aqueous solution. Pre-existing carriers would play the role as “artificial interfaces” to adsorb water-insoluble PC and made them disperse in water. DHA donors were concentrated by a pH-responsive method and presented as supersaturated salt solutions. 153 triacylglycerol lipase structures were analyzed and screened in silico. Transesterification was carried out to further evaluate the six lipase candidates. Lipase B from Candida antarctica (CALB) was the best biocatalyst with 34.8% of DHA incorporation and 80.0% of PLs yields (involving 38.1% PC and 41.9% sn-1 lyso-PC). Toxic organic solvents were avoided. Six possible microunits of our aqueous system consisting of three PLs donors (PC, lyso-PC, sn-glycero-3-PC) and two DHA donors (DHA and DHA salts), were simulated by molecular dynamics (MD) to illustrate the enzymatic mechanism based on diffusional channels, competitive bindings, and enzymatic structures.

Accelerating the precipitation kinetics of nano-sized T1 and S’ phases in Al-Cu-Li alloys by hot-deformation and creep-aging

ABSTRACT It is well known that a Cu/Li ratio over 4.0 leads to significant precipitation hardening in the third generation of Al–Li alloys, which have been widely used in aerospace and aeronautic industries. However, increasing Cu levels not only cancels some gains in weight reduction but also results in reductions in ductility when the traditional age-hardening process is adopted. In this study, we show that higher strength and ductility can be achieved simultaneously by replacing traditional artificial aging with new creep aging and tailoring the entire process from casting to age hardening without changing any nominal chemical compositions. Surprisingly, the precipitation kinetics of AA2060 alloy is significantly enhanced through the combination of hot extrusion, creep aging, and pre-strain compared to traditional artificial aging. For example, at 160°C, it follows the transformation path of supersaturated solid solution (SSSS)→GP zones + δ′+T1 precursors which will further transform into T1 +S’; at 200°C, SSS→ GP zones, and they transform into T1 + S’ immediately. The precipitation of θ′ and δ′ phases is significantly inhibited at elevated temperatures due to the competing relationship with T1 and S’ phases at a peak-aged state. Contrary to traditional knowledge in Al–Li alloys, we have found that the greater extrusion ratio at 33.0 and higher aging temperature at 200°C can give a much higher peak aging strength with average ultimate tensile strength 659 MPa.

Observations of atmospheric new particle formation impacts on cloud condensation nuclei in summer at Mt.Tian

As one of the important sources of aerosols, new particle formation events can affect the spatiotemporal distribution of CCN. To analyze the characteristics of new particle formation (NPF) events and their effects on cloud condensation nuclei (CCN) during the summer at Mt.Tian, the data of aerosol size distribution and CCN number concentrations were measured using an aerosol wide-range particle size spectrometer and a cloud condensation nuclei counter from August 4 to 25, 2019, and combined with meteorological data and polycyclic aromatic hydrocarbons (PAHs) data. NPF events at Mt.Tian occurred seven days during the observation period, accounting for 32% of the observation days, and usually occurred at 13:00 and ended at 17:00 (Beijing Time, same below). NPF events particularly influenced the diurnal variations of aerosol number concentrations in different modes. The number concentrations of nucleation and Aitken modes increased rapidly while the accumulation mode increased slowly during 13:00 and 17:00 on NPF days. The peak particle number concentrations in the nucleation, Aitken and accumulation modes on NPF days were 5360.1 cm−3, 7185.6 cm−3 and 839.3 cm−3, respectively, which were 3.3, 1.8 and 1.7 times higher than those on non-NPF days during 13:00 and 17:00. The meteorological conditions of temperature higher than 20 °C, air pressure lower than 806 hPa, relative humidity (RH) lower than 40% and wind speed higher than 2.2 m s−1 are favorable for the occurrence of NPF events. The NPF events at Mt.Tian can impact the mass concentration of PAHs. More Fluoride (FL) and Phenanthrene (PHE) were generated on NPF days. The mass concentrations of FL and PHE on NPF days were 0.002 ± 0.003 ng m−3 and 0.020 ± 0.010 ng m−3, which were 243.54% and 28.44% higher than those on non-NPF days, respectively. NPF events were conducive to increased CCN concentration at Mt.Tian. After the NPF events, the mean number concentrations of CCN at each supersaturation (SS) on NPF days was about 20%–50% higher than on non-NPF days. The contribution of NPF events to the CCN number concentrations was 35.75%, 28.56%, 44.15%, 42.11% and 29.12% at 0.1%, 0.2%, 0.4%, 0.6% and 0.8% SS, respectively.