High Degree Of Supersaturation Research Articles

The Effect of Precursor Concentration on the Crystallite Size of CeO2 to Enhance the Sulfur Resistance of Pt/CeO2 for Water Gas Shift

To develop customized sulfur–resistant catalysts for the water gas shift (WGS) reaction in the waste–to–hydrogen process, the effects of changing the nucleation conditions of the CeO2 support on catalytic performance were investigated. Supersaturation is a critical kinetic parameter for nuclei formation. The degree of supersaturation of the CeO2 precipitation solution was controlled by varying the cerium precursor concentration from 0.02 to 0.20 M. Next, 2 wt.% of Pt was impregnated on those various CeO2 supports by the incipient wetness impregnation method. The prepared samples were then evaluated in a WGS reaction using waste–derived synthesis gas containing 500 ppm H2S. The Pt catalyst supported by CeO2 prepared at the highest precursor concentration of 0.20 M exhibited the best sulfur resistance and catalytic activity regeneration. The sulfur tolerance of the catalyst demonstrated a close correlation with its oxygen storage capacity and easier reducibility. The formation of oxygen vacancies in CeO2 supports is promoted by the formation of small crystals due to a high degree of supersaturation.

Infrared Thermography Investigation of Crystallization in Acoustically Levitated Supersaturated Aqueous Solution

In this study, crystallization in highly supersaturated aqueous urea solutions was investigated using in situ infrared thermography facilitated by an acoustic levitation apparatus. A notable contribution of this thermographic approach is the identification of a transient heat release signature, particularly pronounced beyond the solubility limit, indicating the enhanced formation of bonds between urea molecules in the supersaturated states. Surprisingly, the temporal evolution of the heat release measurements on an acoustically levitated droplet strongly suggests a two-stage process for urea crystallization. A comprehensive statistical analysis based on classical nucleation theory is used to further investigate the exceptionally high degree of supersaturation and the emergence of prominent heat signatures observed toward the onset of crystallization.

A new hydration kinetic model based on boundary nucleation and growth mechanism with time-dependent growth rate: Application to quantitively characterize the influence of alkali on the early hydration of cement

In this study, a boundary nucleation and growth model with a time-dependent growth rate was proposed to quantitively characterize the precipitation of CSH. The newly constructed model was typically applied to quantitively analyse the influence of alkali content on the growth of CSH, and the value-taking equations of the time-dependent growth rate of CSH in various alkali content systems were proposed and verified. The experimental and simulation results proved that a high soluble alkali content stimulated early hydration (within the initial several hours) and inhibited the late growth of CSH (>20 h) in cement paste. The time-varying ion concentrations in cement solutions were the main driving force for the change in the growth rate of CSH with time. Likewise, the variation in the aqueous phase properties of cement pastes also explains the influence of alkali content on the growth rate of CSH, i.e., the high initial pH of the solution with high soluble alkali led to the high supersaturation degree and high growth rate of CSH, consuming large amounts of calcium ions and in turn reducing the later supersaturation degree and growth rate. The newly constructed model is also expected to precisely characterize the factors that have a significant influence on the precipitation of cement hydrates.

Revisiting scaling of calcium sulfate in membrane distillation: Uncertainty of crystal-membrane interactions

Scaling of calcium sulfate (CaSO4) is a stumbling block to the development of membrane distillation (MD), which holds promise for the treatment of saline water/wastewater. Despite increasing efforts made to understand the scaling behavior of CaSO4 in a process of MD and thereby develop strategies for mitigating the negative effects, considerable uncertainty remains about occurrence of the wetting and structural damage that could result from the strong crystal-membrane interactions. This study combined experimental and theoretical approaches to corroborate that a higher degree of supersaturation could be achieved by concentrating the CaSO4 in the feed at a faster rate; the elevated supersaturation would be in favor of exerting substantially high crystallization pressure on the membrane structures. In particular, the theoretical analysis established two dimensionless groups for measuring the relative importance of the concentration effect and quantifying the essential role played by the crystalline growth, respectively. In addition to alleviating the uncertainty, this study would be beneficial to the design of MD processes with improved scaling resistance.

Lateral variations in the Hosen 8‐2 vein in the Hishikari deposit, Japan: Implications for high Au‐grade zone

AbstractLateral sampling of each blasting interval (~ 2.6 m) along a 79 m strike length was conducted for the Hosen 8‐2 vein on the −5 ML (mining level, meters relative to sea level) of the Main ore zone in the Hishikari epithermal Au deposit, Kagoshima, Japan. The horizontal variation of mineral textures, bulk chemical compositions, and fluid inclusion temperatures and apparent salinity of ore fluids were determined. The major gangue minerals of the quartz veins studied include quartz and adularia with minor amounts of calcite and smectite. The major ore minerals include electrum, galena, and sphalerite with minor pyrite, petzite, and hessite. Electrum commonly occurs in a discrete band with microcrystalline quartz, granular adularia, and smectite. The electrum‐bearing band is followed by tabular adularia, and finally by granular or comb quartz. Mineral textures that indicate high degrees of supersaturation with respect to amorphous silica (presently quartz with microcrystalline/mosaic and feathery textures) and adularia (with tabular, rhombic, and granular textures) were common throughout the vein strike. Bulk chemical analyses indicate that Au grade is positively correlated with Ag, Bi, Pb, and Te contents. A bonanza zone with Au grades up to 10,800 ppm occurs in the central part of the Hosen 8‐2 vein on the −5 ML, and is associated with high adularia content, calculated as adularia / (quartz + adularia). The wide lateral variation in the geochemical composition contrasts with the consistent association of electrum with microcrystalline quartz, granular adularia, and smectite throughout the Hosen 8‐2 vein on the −5 ML. Fluid inclusion microthermometry of primary and pseudosecondary inclusions in quartz and adularia yielded histogram modes of homogenization temperature between 160 and 240°C; the most frequent mode is 200–210°C, with most data within ±10°C from this value. The maximum ice‐melting temperature of most samples excluding late comb quartz is −1.5°C, which is equivalent to an apparent salinity of 2.6 wt% NaCl eq. The wide variation in ice‐melting temperatures and apparent salinities (up to 5.2 wt% NaCl eq.) may be due to dissolved CO2 in the fluids, while the sharp decrease in apparent salinity with temperature decrease indicates CO2 loss due to fluid boiling during vein formation. The intimate association of electrum with microcrystalline quartz that recrystallized from amorphous silica indicate sharp boiling and vapor loss as the primary mechanism of Au deposition in the Hosen 8‐2 vein.

Laser Directed Energy Deposition of an AlMgScZr-Alloy in High-Speed Process Regimes.

Aluminum-magnesium-scandium-zirconium (AlMgScZr) alloys need to be rapidly cooled from the liquid state to obtain a high degree of solute supersaturation that helps to exploit the precipitation hardening potential of the material. While AlMgScZr alloys have been successfully used in laser powder bed fusion (LPBF) processes, there has been little research in the field of laser directed energy deposition (DED) of the material. The limited previous studies have shown that the performance of AlMgScZr parts fabricated with DED only reached about 60% of that of the parts fabricated with LPBF. In view of breaking through the limitation associated with the process conditions of conventional DED, this work demonstrates the DED of AlMgScZr alloys in high-speed process regimes and elucidates the mechanism of enhancing the hardness and tensile strength of AlMgScZr alloys by increasing the cooling rate by one to two orders of magnitudes, as well as reducing the track overlapping and the porosity of the specimens during the process. A maximum average hardness of nearly 150 HV0.1 and a max. tensile strength of 407 MPa are obtained by using an energy per unit length of 5400 J/m and a powder feed rate per unit length of 0.25 g/m.

The impact of the large-scale circulation anomalies in the northern hemisphere on air quality in Wuhan of China during the Spring Festival in 2020

During the 2020 Chinese Spring Festival extended holidays and the COVID-19 period in Wuhan, the “quasi-zero emissions increase” occurred due to the human activities have a considerably lower impact on air quality. A new scientific question of concern: Why has high of O3 and PM2.5 still been observed? The comparative analysis of the influences of anomalous atmospheric circulation and weather conditions during this special period in 2019–2020 with those in the historical years can be useful. The results in the study were as follows:(1) Even during this “quasi-zero emissions increase” period, the concentrations of O3 and PM2.5 are higher than normal, with O3 being significantly higher in Wuhan. Which is associated with a anomaly large-scale humid/warm water vapor transport in the Northern Hemisphere which is significantly different from that of the same period with historical more-haze years. (2) In this scenario, the large-scale humid/warm water vapor transport brings sustained high-humidity water vapor lifting conditions to north China. The daily cycling change of the sun's zenith angle to support the high-humidity and high-condensation condition are conducive to the elevation of high condensation (fc) and degree of super-saturation (S) going up to the peak of S >10%. Under the condition driven by high fc, it causes the power exponent law to be followed converting NO2 to O3, thereby resulting in an increase in O3 concentration. This additional contribution to O3 concentration is as high as 37% than those from pure chemical process. (3) An objective quantitative reversal method for calculating the monthly threshold in fc is given based on the power exponential conversion law by the observed data. It can be prospectively applied to assess the feedback on the impact of pollution on urban climate.

Enhancing the mechanical performance of Al–Zn–Mg alloy builds fabricated via underwater friction stir additive manufacturing and post-processing aging

• This is the first time to report that in-process water cooling can effectively solve the macro-scale and local softening problems in the FSAM of the age-hardenable Al–Zn–Mg alloy. • Homogeneous microstructures and mechanical properties are obtained in the underwater FSAM build. • After natural aging, the UTS of the water-cooled build is slightly higher than that of the base metal. • The underlying mechanism of the improved mechanical properties correlated with microstructure developed during FSAM process is discussed and clarified. Our previous studies have demonstrated that underwater friction stir additive manufacturing (FSAM) could effectively suppress the macroscale softening of the fabricated Al–Zn–Mg–Cu alloy build from top to bottom. However, the accompanying local softening problem, i.e., a low-hardness region at the bottom of each stir zone, becomes prominent. In this study, an Al–Zn–Mg alloy with low quench sensitivity was used to fabricate a multilayered build via underwater FSAM. In-process water cooling could effectively solve the macroscale and local softening problems in the FSAM of the Al–Zn–Mg alloy and improve the mechanical performance of the build. The microhardness and ultimate tensile strength (UTS) of the water-cooled build in as-fabricated and aged states were more uniform along the building direction and higher than those of their counterparts. After 90 days of natural aging, the UTS of the water-cooled build in building and traveling directions reached 398 and 400 MPa, respectively, slightly higher than that of the base metal (392 MPa). The enhancement in the mechanical performance of the water-cooled build was attributed to a high degree of supersaturation and age-strengthening ability because of a high cooling rate of the underwater FSAM process and low quench sensitivity of the base metal.

Insights into the wetting phenomenon induced by scaling of calcium sulfate in membrane distillation

Development of water/wastewater treatment based on membrane distillation (MD) suffers from the drawback that the hydrophobic membrane could be wetted for various reasons. Despite significant efforts, there is uncertainty in addressing the wetting induced by scaling of calcium sulfate, which is ubiquitous and recalcitrant in MD processes. This study made the first attempt to analyze the interplay between the growing crystals and the porous structures in the framework of Stoney's equation. Optical coherence tomography (OCT) was exploited to measure the membrane shift, whereby the scaling-induced deformation was correlated with the variation in stress created in the crystal-containing layer. Along with the stress analysis, the OCT-based characterization was combined with conventional approaches to ascertain the dependence of the scaling-induced wetting on the rate of concentrating the crystallizing species when arriving at a high degree of supersaturation in the feed. This study would refine the physical picture for better understanding crystal-membrane interactions that result in not only the wetting phenomenon but also the irreversible damage of membrane structures, thereby lending itself to the development of strategies for MD-based applications with improved efficiency.

Microdialysis and nanofiltration allow to distinguish molecularly dissolved from colloid-associated drug concentrations during biomimetic dissolution testing of supersaturating formulations

Many new drug entities are poorly water-soluble and thus require solubility-enhancing formulations to ensure sufficient bioavailability. On the other hand, it is more and more accepted that not all “dissolved” states of a drug contribute equally to enhanced absorption, i.e. an increase in apparent solubility does not necessarily go in parallel with an increase in molecularly dissolved drug, the latter being regarded as the key driving force for absorption. Our study aimed to provide time-resolved information on the dissolution, supersaturation, and precipitation behavior of molecularly dissolved drug as released from an amorphous solid dispersion and a surfactant-containing crystalline suspension of Posaconazole (PCZ), a weakly basic and poorly water-soluble drug. Thereby, we aimed to gain a deeper mechanistic understanding of enabling formulation principles and possibly establish a dynamic biopharmaceutical assessment tool for molecularly dissolved drug released from enabling formulations.A two-staged dissolution test, with media transition from simulated gastric fluid (SGF) to fasted state simulated intestinal fluid (FaSSIF), was performed with three alternative sampling approaches in parallel: the classical bench centrifugation approach was used to assess total dissolved concentrations, while a nanofiltration method and a microdialysis setup were tested for their ability to discriminate molecularly and colloid-associated drug concentrations over time. For comparison, a single-stage dissolution setup was performed, where a marketed PCZ suspension was dispersed in biomimetic media with increasing amounts of solubilizing agents to understand their effect on the concentration of molecularly dissolved drug.It was demonstrated that the microdialysis setup allowed to follow the molecularly dissolved drug concentration in a time-resolved manner during the single-and two-stage dissolution tests with marginal delays. Interestingly, the PCZ concentrations measured by the nanofiltration approach differed from both, the molecularly dissolved (assessed by microdialysis) and apparently dissolved (assessed by centrifuge) PCZ concentrations, indicating that nanofiltration may allow to differentiate between different colloid-associated (apparently) dissolved drug species. Moreover, it was shown that the release of the molecularly dissolved drug from an amorphous solid dispersion did not correlate at all with the results obtained by the centrifugation method: While this conventional sampling revealed a classical spring and parachute concentration/time-profile with a high degree of (apparent) supersaturation, the concentration of molecularly dissolved drug (assessed by the microdialysis setup) indicated an initial short decline of PCZ concentration, followed by a prolonged (moderate) molecular supersaturation. This observation may give rise to a re-thinking of the current mechanistic understanding of how amorphous solid dispersions enhance oral bioavailability. In essence, the current study provides data which indicate a benefit of both the microdialysis sampling and nanofiltration approaches for the in vitro biopharmaceutical assessment of enabling drug formulations.

Ultrasound‐Assisted Slug‐Flow Tubular Crystallization for Preparation of Fine Ibuprofen Crystals

AbstractIbuprofen fine crystals prepared by commonly used methods have some problems such as low‐crystallinity product and uneven distributed particle size. An ultrasonic‐assisted tubular crystallization system was developed. The effects of tubular crystallization temperature, supersaturation, residence time, surfactant, and flow pattern on the crystal size distribution and average particle size were studied. It was found that ultrasound promotes nucleation and reduces crystal aggregation. Ibuprofen crystals with an average particle size of 6.23 μm were formed owing to the high degree of continuous supersaturation and promoted micromixing. Finally, a possible mechanism of enhancement of micromixing under ultrasonic and slug flow on tubular crystallization was proposed.

Rhombic calcite microcrystals as a textural proxy for meteoric diagenesis

Numerous Phanerozoic limestones are comprised of diagenetic calcite microcrystals formed during mineralogical stabilization of metastable carbonate sediments. Previous laboratory experiments show that calcite microcrystals crystallizing under conditions similar to those that characterize meteoric diagenetic settings (impurity-free, low degree of supersaturation, high fluid:solid ratio) exhibit the rhombic form/morphology, whereas calcite microcrystals crystallizing under conditions similar to those that prevail in marine and marine burial diagenetic settings (impurity-rich, high degree of supersaturation, low fluid:solid ratio) exhibit non-rhombic forms. Based on these experimental observations, it is proposed here that rhombic calcite microcrystals form exclusively in meteoric environments. This hypothesis is tested using new and previously published textural and geochemical data from the rock record. These data show that the vast majority of Phanerozoic limestones characterized by rhombic microcrystals also exhibit petrographic and/or geochemical evidence (depleted δ13C, δ18O, and trace elements) indicative of meteoric diagenesis whereas non-rhombic forms are associated with marine burial conditions. By linking calcite microcrystal textures to specific diagenetic environments, our observations bring clarity to the conditions under which the various microcrystal textures form. Furthermore, the hypothesis that rhombic calcite microcrystals form exclusively in meteoric environments implies that this crystal form may be a useful textural proxy for meteoric diagenesis.

Determination of the Activation Energies of Phase Transition for Calcium Orthophosphates Based on Powder X‐Ray Diffraction Data

AbstractKinetic studies of the transformation of calcium orthophosphates metastable precipitates are performed under different synthesis conditions. The phase composition and degree of crystallinity are investigated by X‐ray powder diffraction analysis. In acidic solution, precipitates of CaHPO 4 . 2H 2 O (DCPD) and CaHPO 4 (DCPA) are formed at the early stage of precipitation, with the degree of crystallinity at the range of 17–35%. Specifically, DCPD precipitates at 30 °C and anhydrous DCPA at 50 °C. In alkaline solution (pH 8–10), only amorphous forms of calcium orthophosphate are precipitated, which is explained by the high degree of supersaturation. The effect of pH on the composition of precipitates is illustrated by the solubility isotherms of pure calcium orthophosphates. It is determined the activation energy of phase transformation of calcium orthophosphate from X‐ray powder diffraction patterns. Based on this relationship developed, the activation energies for the recrystallization DCPD and DCPA are 10.2 and 13.1 kJ mol−1, respectively, and for the phase transition of DCPD to DCPA – 36.7 kJ mol−1. Further recrystallization to most thermodynamically stable hydroxyapatite occurs at the activation energy of 5.2 kJ mol−1. These findings are critical to the phase transition and transformation of calcium phosphate minerals.

Continuous Crystallization of Phosphoric Acid Using Suspension Crystallizer: Effect of Operating Conditions on Purity of Crystals

AbstractIn this study, batch crystallization via indirect cooling and continuous crystallization via direct and indirect cooling of phosphoric acid hemihydrate (H3PO4.1/2H2O) from the mixed acid solution of phosphoric acid and acetic acid are performed. In batch crystallization, needle‐shaped crystals are obtained, and the impurity concentration of acetic acid in the crystals is 4.2 wt%. Primary nucleation occurred under a high degree of supersaturation, and the metastable zone width for secondary nuclei is narrow. In contrast, in continuous crystallization via indirect cooling, scaly crystals are obtained, and the acetic acid impurity concentration therein is 2.0 wt%. Additionally, continuous crystallization via direct contact cooling is performed, the crystal shape and impurity concentration under direct cooling are similar to those under indirect cooling, suggesting the possibility to downsize the apparatus. Through utilization of the equipment and approach elaborated herein, the correlation between the operating conditions and crystal quality can be assessed.

Colloidal transport and flocculation are the cause of the hyperenrichment of gold in nature

Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. A major weakness of this hypothesis is that it cannot readily explain the formation of ultrahigh-grade gold veins. This is a consequence of the relatively low gold concentrations typical of ore fluids (tens of parts per billion [ppb]) and the fact that these "bonanza" veins can contain weight-percent levels of gold in some epithermal and orogenic deposits. Here, we present direct evidence for a hypothesis that could explain these veins, namely, the transport of the gold as colloidal particles and their flocculation in nanoscale calcite veinlets. These gold-bearing nanoveinlets bear a remarkable resemblance to centimeter-scale ore veins in many hydrothermal gold deposits and give unique insight into the scale invariability of colloidal flocculation in forming hyperenriched gold deposits. Using this evidence, we propose a model for the development of bonanza gold veins in high-grade deposits. We argue that gold transport in these systems is largely mechanical and is the result of exceptionally high degrees of supersaturation that preclude precipitation of gold crystals and instead lead to the formation of colloidal particles, which flocculate and form much larger masses. These flocculated masses aggregate locally, where they are seismically pumped into fractures to locally form veins composed largely of gold. This model explains how bonanza veins may form from fluids containing ppb concentrations of gold and does not require prior encapsulation of colloidal gold particles in silica gel, as proposed by previous studies.

Tuning Polymorphs and Morphology of Microbially Induced Calcium Carbonate: Controlling Factors and Underlying Mechanisms.

Microbially precipitated calcium carbonate (CaCO3) has drawn broad attention due to its potential applications in various areas, for example, biocementation, medicine, and soil reinforcement. Sporosarcina pasteurii (S. pasteurii), formerly known as Bacillus pasteurii, has been investigated for CaCO3 biomineralization due to its high ureolytic activity. A high degree of supersaturation with respect to the presence of bacterial cell wall, extracellular polymeric substances, and organic byproducts of bacterial activity plays an important role in the formation and stabilization of CaCO3 polymorphs. Although microbially induced CaCO3 and its polymorphs have been investigated broadly, the mechanisms of polymorph selection and morphological evolution are not well understood. This study employs ex situ approaches to address the complication of biomineralization in the presence of living organisms and to elucidate how solution chemistry, bacterial activity, and precipitation kinetics alter the polymorphism and morphology of CaCO3 induced by S. pasteurii. The results indicate that in the presence of enough calcium ions and urea (as a carbonate source), the bacterial activity favors the formation and stabilization of vaterite. The morphological observations also provide valuable information on the particles’ microstructure. The morphology of calcite evolves from single crystal to polycrystalline structures, and the morphology of vaterite evolved from spherical to oval-shaped structures on increasing the organic material concentration. Specific functional groups also exert morphological control on CaCO3 polymorphs. However, the sensitivity of the calcite polymorph to the composition and orientation of these functional groups is higher compared to that of the vaterite polymorph. These findings offer important insights that can be used to constrain a set of experimental conditions for synthesizing a certain polymorph ratio for vaterite/calcite or a particular morphology of each polymorph and shed light on the crystallization and phase transformation mechanisms in such complicated bioenvironments.

Estane‐Assisted Preparation of Submicron β‐Form HMX Particles through Antisolvent Crystallization

AbstractOctahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) particles were prepared through solvent‐antisolvent crystallization at room temperature by using dimethyl sulfoxide and ethanol as a solvent and an antisolvent, respectively. Estane, which has been used as a polymer binder in polymer‐bound explosives, was added to retard nucleation and inhibit crystal growth. The particles were characterized using scanning electron microscopy, X‐ray diffraction analysis, nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. Owing to the nucleation at a high degree of supersaturation, thermodynamically unstable submicron non‐β‐form HMX particles were formed initially. Their morphology was changed to β‐form; the submicron size was maintained while the particles were entrapped in Estane. Estane was removed by washing with tetrahydrofuran, and the purity of the submicron β‐form HMX particles was greater than 99 %.

Efficiency of microbially-induced calcite precipitation in natural clays for ground improvement

Microbially-induced calcite precipitation (MICP) is a promising technique to improve the engineering properties of soft soil in a sustainable, environmentally friendly, and energy saving manner. This study determined the suitable chemical condition to induce MICP activity from alkaliphilic urease-producing Sporosarcina pasteurii bacterium, and to explore the MICP activity’s effectiveness in improving the mechanical properties of three types of natural fine-grained soils (Kaolin clay, Laterite, and Bangkok clay). Untreated and treated clays were evaluated by the free-free resonant frequency test, unconfined compression test, and their microstructures and chemical compositions. The results showed that a urea-Ca2+ input rate of 7.5 mmol/h efficiently promoted the precipitation of calcite by bacteria, as indicated by the highest degree of media clogging in sand column tests. A higher urea-Ca2+ input rate created soil samples that exhibited a high degree of supersaturation, which impacted the precipitation pattern at the microscale, resulting in less contact between soil particles; this was caused by the increase in salinity of the solution to a level that inhibited bacterial activity and retarded calcite precipitation. Once the optimal urea-Ca2+ input rate was determined, bacterial cultures were introduced into samples of each clay, and fed with the optimal chemical mixture while being maintained at room temperature (25–30 °C) for 7 d. Increases in the samples’ stiffness and shear strength coincided with increased amounts of precipitated calcite. Enhancements to each clay type’s strength parameters were dependent on the natural characteristics of clay. Specifically, liquid media carrying the necessary nutrients for MICP activity could not efficiently permeate through the clayey soil with a high plasticity, resulting in a lower observable degree of MICP activity to improve the soil’s characteristics.

Synthesis of uniform nanometer-thick graphite film on polycrystalline Ni substrate with ultrafine grains

When a polycrystalline Ni foil is used as the substrate for the chemical vapor deposition synthesis of multilayer-graphene or nanometer-thick graphite films (NGFs), these films always exhibit uneven morphologies and qualities on Ni grains with different orientations. In this study, we fabricated a carbon-supersaturated Ni foil (ss-Ni foil) to function as a carbon source through an ultrafast cooling process (∼180 °C/s), while an additional Ni film was sputtered on the ss-Ni foil to act as a buffer layer and a new surface for NGF growth. By re-annealing the Ni film/ss-Ni foil system at a low temperature (∼650–800 °C) within a short duration, NGF can rapidly form on the Ni film owing to the high supersaturation degree of the ss-Ni foil. The grain growth of the Ni film is limited by the low-temperature growth process, and the ultrafine grains of Ni film averaged the grain orientation effect from the Ni foil. The NGF formed on the Ni film/ss-Ni foil showed a significant improvement in thickness and quality uniformity, and we studied the influences of Ni film thickness as well as re-annealing temperature and time on the diffusion of carbon in the Ni film/ss-Ni foil system and summarized the growth mechanism.

Enhanced Oral Bioavailability of Resveratrol by Using Neutralized Eudragit E Solid Dispersion Prepared via Spray Drying.

In this study, we designed amorphous solid dispersions based on Eudragit E/HCl (neutralized Eudragit E using hydrochloric acid) to maximize the dissolution of trans-resveratrol. Solid-state characterization of amorphous solid dispersions of trans-resveratrol was performed using powder X-ray diffraction, scanning electron microscopy, and particle size measurements. In addition, an in vitro dissolution study and an in vivo pharmacokinetic study in rats were carried out. Among the tested polymers, Eudragit E/HCl was the most effective solid dispersion for the solubilization of trans-resveratrol. Eudragit E/HCl significantly inhibited the precipitation of trans-resveratrol in a pH 1.2 dissolution medium in a dose-dependent manner. The amorphous Eudragit E/HCl solid dispersion at a trans-resveratrol/polymer ratio of 10/90 exhibited a high degree of supersaturation without trans-resveratrol precipitation for at least 48 h by the formation of Eudragit E/HCl micelles. In rats, the absolute oral bioavailability (F%) of trans-resveratrol from Eudragit E/HCl solid dispersion (10/90) was estimated to be 40%. Therefore, trans-resveratrol-loaded Eudragit E/HCl solid dispersions prepared by spray drying offer a promising formulation strategy with high oral bioavailability for developing high-quality health supplements, nutraceutical, and pharmaceutical products.