Two-stage Behavior Research Articles

Positive Sorption Behaviors in the Ligand Exchanges for Water-Soluble Quantum Dots and a Strategy for Specific Targeting.

N,N,N',N'-Tetramethylethylenediamine (TMEDA) and ethylenediamine (EDA) were investigated in-depth in the ligand exchanges for water-soluble CdSe quantum dots (QDs). TMEDA could assist the phase transfer of QDs from apolar solvents to the aqueous solutions as stabilized by mercaptopropionic acid (MPA). We successfully maintained the stability of a series of MPA-capped QDs of different ligand densities for NMR characterizations in aqueous solutions. The proton NMR spectroscopies of MPA of the binding state were used to analyze the ligand densities on the surface of QDs, which were not explored in the past. The binding thermodynamics of the surface ligands of QDs, as analyzed using the Hill equation, demonstrated a positive promoting effect and possible interactions between ligands. EDA in the purification process underwent a spontaneous adsorption with two-stage thermodynamic behaviors as characterized by isothermal titration calorimetry. Due to the positive role of the already adsorbed ligands, excess EDA would further attach to the surface of QDs in the form of non-bonded physisorption, greatly improving the quantum yield (QY) of QDs, and the ligand of this part would almost not change the stability of QDs. We proposed a strategy for the preparation of aqueous QDs with a high QY, followed by fluorescence quenching-enhancement cycles caused by purification-adsorption operations. The strategy made it possible for the preparation of functional QDs with small molecules after purification operations. Kinetics of the sorption of ligands on the surface of QDs were determined by fluorescence spectroscopy. Modified pseudo-second-order kinetics after consideration of the ligand-ligand interaction effect could well analyze the kinetic data. This kinetic model had advantages over the previous ligand exchange model in terms of accuracy, reproducibility, and physical significance. Finally, we used the above strategy for the design of fluorescent QDs for bioimaging of lysosomes, mitochondria, and cancer cells. This work can simplify the preparation of multifunctional fluorescent QDs and avoid complicated ligand design.

Development and In Vitro Evaluation of Biocompatible PLA-Based Trilayer Nanofibrous Membranes for the Delivery of Nanoceria: A Novel Approach for Diabetic Wound Healing.

The attempts to explore and optimize the efficiency of diabetic wound healing’s promotors are still in progress. Incorporation of cerium oxide nanoparticles (nCeO2) in appropriate nanofibers (NFs) can prolong and maximize their promoting effect for the healing of diabetic wounds, through their sustained releases, as well as the nanofibers role in mimicking of the extra cellular matrix (ECM). The as-prepared nCeO2 were analyzed by using UV–Vis spectroscopy, XRD, SEM–EDX, TEM and FTIR, where TEM and SEM images of both aqueous suspension and powder showed spherical/ovoid-shaped particles. Biodegradable trilayer NFs with cytobiocompatibility were developed to sandwich nCeO2 in PVA NFs as a middle layer where PLA NFs were electrospun as outer bilayer. The nCeO2-loaded trilayer NFs were characterized by SEM, XRD, FTIR and DSC. A two-stage release behavior was observed when the nanoceria was released from the trilayer-based nanofibers; an initial burst release took place, and then it was followed by a sustained release pattern. The mouse embryo fibroblasts, i.e., 3T3 cells, were seeded over the nCeO2-loaded NFs mats to investigate their cyto-biocompatibility. The presence and sustained release of nCeO2 efficiently enhance the adhesion, growth and proliferation of the fibroblasts’ populations. Moreover, the incorporation of nCeO2 with a higher amount into the designed trilayer NFs demonstrated a significant improvement in morphological, mechanical, thermal and cyto-biocompatibility properties than lower doses. Overall, the obtained results suggest that designated trilayer nanofibrous membranes would offer a specific approach for the treatment of diabetic wounds through an effective controlled release of nCeO2.

Water uptake and interfacial shear strength of carbon/glass fiber hybrid composite rods under hygrothermal environments: effects of hybrid modes

The hygrothermal aging of fiber reinforced polymer (FRP) composite rod served as bridge cables played a key role on the long-term service performances. In the present paper, two types of pultruded carbon/glass fiber reinforced epoxy hybrid composite rods, one with uniformly dispersed carbon and glass fibers, and the other with glass fiber shell and carbon fiber core, were investigated on the water uptake and interface shear strength. The aging condition was immersion in deionized water at 40 °C, 60 °C and 80 °C. Interface shear strength degradation mechanism was revealed by thermal analysis and microstructure analysis. It was found that the water absorption of two types of hybrid rods represented the two-stage behavior. For the rod of uniform fiber dispersion, more water uptake in the second stage occurred compared to that of the shell/core rod, which was attributed to the resin rich area and interface debonding of fiber/resin. Long-term hygrothermal exposure led to a remarkable degradation in the interfacial shear strength of the rods, up to 17.5% ∼ 42.1%. The resin plasticization and interface debonding were the main factors contributed to the strength degradation. Based on the Arrhenius equation, the long-term life prediction of the interfacial shear strength under two typical bridge service environments was conducted to the design guideline of hybrid rods in the bridge engineering.

Investigation of inhomogeneous degradation in large-format lithium-ion batteries

Large-format prismatic lithium-ion batteries (LIBs) with 52 Ah capacity and Verband Der Automobilindustrie (VDA) standard dimensions were cycled under a preloading force of 2.5 kN at 25 °C. When cycled, the LIBs exhibited a two-stage degradation behavior characterized by a first linear degradation stage and a second nonlinear degradation stage. The two-stage behavior which is also called rollover failure is investigated by post-mortem analysis. When the jelly roll was unfolded, lithium plating and delamination of cathode materials were found in the curved areas. From the scanning electron microscopy (SEM) images, the graphite particles in the curved areas were deformed and cracked. The LIB under a higher preloading force of 5.5 kN was found to have shorter cycle life, indicating mechanical force is one of the factors that lead to the rollover failure. The degradation mechanism was thoroughly illustrated by applying shift voltage-resistance voltage (SV-RV), differential voltage (DV) and electrochemical impedance spectroscopy (EIS) measurements. The SV-RV analysis suggests that lithium plating occurs after around 300 cycles. The shifting to low capacity and broadening of peaks in dV/dQ curves indicate that the second nonlinear degradation stage could be caused by combining loss of active materials (LAM) and loss of lithium inventory (LLI). In the nonlinear degradation stage, ohmic resistance (Rs) and charge transfer resistance (Rct) is dramatically increased as characterized by EIS measurement. The increased Rs and Rct further support the conclusion that LLI and LAM are the dominating degradation mechanism in the nonlinear degradation stage.

A numerical study on the two-stage combustion behaviour of n-heptane droplet clouds

A numerical study on the two-stage combustion behaviour of n-heptane droplet clouds

External group combustion of droplet clouds under two-stage autoignition conditions

The present study aims to extend the understanding of the external group combustion for droplet clouds under two-stage autoignition conditions. First, an exemplar case has been chosen to analyze the two-stage ignition behavior and flame structure. It was found that the fuel vapor transport of the droplet cloud is mainly supported by the thin vaporization layer near the edge of the cloud, which is the dominant factor of the ignition process. The case shows that a typical two-stage ignition includes the following detailed processes: first stage ignition, quasi-steady non-premixed cool flame, second stage ignition, and premixed hot flame. Three possible ignition modes for droplet clouds were identified through parametric studies, i.e. no ignition, single-stage ignition, and two-stage ignition. The transition between these modes is mainly controlled by the competition between chemical reaction and the vaporization of a thin layer of fuel droplets. Phase diagrams of different ignition modes at different ambient temperatures and sub parameters of the group number were presented. The previous group number G = 2πndRc2 demonstrated unsatisfactory prediction in the ignition modes of the droplet clouds. Basing on the vaporization layer feature of the droplet clouds, a new dimensionless group ignition number with much better predictability is first proposed in this work, i.e. Gig = 4πn2/3d2. The physical meaning of Gig is the dimensionless total surface area of droplets within a local layer.

An experimental investigation on two-stage low-temperature heat release in iso-octane auto-ignition

A recent computational study showed that iso-octane exhibits a two-stage heat release behavior in the first-stage low temperature ignition regime under certain ranges of initial temperatures and pressures. To explore this computational result, ignition delay time measurements were conducted using a rapid compression machine (RCM) at three different conditions. The experimental observations indeed substantiate the computational results of two-stage heat release in the low-temperature auto-ignition process. Comparison between experimental measurements and simulation results using three different reaction models was also conducted, showing closeness in the timing and intensity of the two-stage heat release for two of them.

Ignition and flame stabilisation of primary reference fuel sprays at engine-relevant conditions

This study aims to investigate the underlying processes governing ignition and flame stabilisation in compression-ignition (CI) engine-relevant conditions. The experiments feature a canonical configuration with a single fuel jet injected into a constant-volume combustion chamber. Primary reference fuels (PRFs), including PRF100 (neat iso-octane, a gasoline surrogate), PRF80 (a blend of 80 vol.% iso-octane and 20 vol.% n-heptane) and PRF0 (neat n-heptane, a diesel surrogate), were tested to simulate changes in fuel ignition quality inside a quiescent steady environment with an ambient density of 22.8 kg/m3 and an O2 concentration of 15 vol.%. The ambient gas temperatures were controlled at 1150 K (PRF100), 1120 K (PRF80) and 900 K (PRF0), in order to adapt to the fuel reactivity so that a constant ignition delay of 1.15 ms can be achieved for all blends. This approach was employed in order to substantially reduce the effect of fuel-oxidiser mixing prior to ignition while highlighting the effect of fuel chemistry on the ignition process and flame evolution. Under the test conditions of this study, optical imaging reveals that the blends with higher iso-octane content exhibit a faster spreading of combustion after ignition and establish a steady lifted flame that is closer to the nozzle. Imaging by CH2O-PLIF indicates that blends with higher iso-octane content produce CH2O that is distributed across larger portions of the jet at an earlier timing when compared to neat n-heptane that shows a propagating first-stage ignition through the fuel jet. Supporting unsteady flamelet calculations are presented to investigate the effect of chemistry and turbulent mixing. The flamelet calculations agree qualitatively in several respects to the experiments, especially in the spatial and temporal trends for CH2O production and consumption. Synthesis of the flamelet and experimental results suggests that for the iso-octane-containing fuels, CH2O is formed via single-stage ignition reactions rather than exhibiting the typical two-stage ignition behaviour which is found in the pure n-heptane fuel case. Furthermore, the flamelet calculations suggest high-temperature ignition occurs first in lean mixtures in the iso-octane-containing fuel cases, but in rich mixtures for the PRF0 case. If autoignition is the mode of flame stabilisation, this provides an explanation for why the PRF100 and PRF80 cases stabilise further upstream, since lean mixtures have longer residence times, experience lower scalar dissipation rate, and may be more likely to be exposed to a supporting peripheral reservoir of hot products, should one exist. Overall, this study provides insights into the roles of fuel chemistry and turbulent mixing on the ignition and combustion behaviour of PRFs under engine-relevant conditions.

Two-stage aerosol formation in low-temperature combustion

Low-temperature combustion is a promising strategy for reducing pollutant formation in internal combustion engines. However, there is a lack of understanding of how the chemistry governing the differences in ignition between low-temperature and conventional combustion affects the emission rates and physicochemical properties of particulate matter (aerosols). Here, we conducted combustion experiments in an atmospheric-pressure reactor controlled at constant equivalence ratio (ϕ = 2.3) and O2/N2 = 0.06, and at temperatures varied between 250 °C and 1035 °C. We used two fuels: toluene, which has high sooting propensity, and n-heptane, which has a comparatively lower sooting propensity but exhibits two-stage ignition that is not present in toluene combustion. We performed real-time measurements of aerosol size distributions, volatility, and light-absorption properties. We also performed offline molecular-size characterization. Aerosols emitted from both fuels were comprised of light-absorbing organics that are categorized as brown carbon. At the highest combustion temperature (1035 °C), the aerosol emissions from toluene combustion were a factor of 20 larger than n-heptane. The aerosol emissions from toluene combustion had more abundance of large molecular-size species, were less volatile, and were more light-absorbing than n-heptane. For both fuels, aerosol emission factors exhibited a steep drop with decreasing temperatures. However, there was a resurgence in aerosol emissions at lower temperatures with a peak at 290 °C for n-heptane combustion that was not observed for toluene. This is consistent with chemical kinetics simulations that show prominent two-stage ignition behavior for n-heptane, but not for toluene.

Perm-waved human hair: a thermorheologically complex shape memory composite

A “permanent” bent shape can be imposed on a straight human hair by a two-stage reduction/oxidation (perm-waving) process. The process relies on the molecular level on sulfhydryl/disulfide interchange as bond exchange reaction (BER). We expected a well-documented transition temperature around 60°C to be the trigger for the shape memory (SM) process of perm-waved hair. We confirm the existence of the SM process as such and investigate its time and temperature dependence. The results show a two-stage SM behavior, implying two distinct variations of the BER. The model to fit the data contains two fractional, normalized, elastic bending rigidities, which are strictly compensatory. They show Arrhenius-type temperature dependence and a common activation energy (EA) of ∼−12 kJ/mol. The characteristic relaxation time for the first SM process shows little, if any, temperature dependence (EA = −4 ± 2.7 kJ/mol). This is in contrast to the second process (EA = −58 ± 5.5 kJ/mol) but in line with the expected properties of the suggested BERs. None of the parameters shows any sign of the expected trigger transition (∼60°C). We hypothesize that this specific transition occurs only for large tensile deformations, when specific SS bonds in the intermediate filaments of hair are activated. There is thus no specific “trigger” transition for the SM behavior of bent, perm-waved hair.

Dynamics of driven polymer transport through a nanopore

The transport of polymers across nanoscale pores underpins many biological processes, such as the ejection of bacteriophage DNA into a host cell and the transfer of genes between bacteria. The movement of polymers into and out of confinement is also the basis for a wide range of sensing technologies used for single-molecule detection and sequencing. Acquiring an accurate understanding of the translocation dynamics is an essential step in the quantitative analysis of polymer structure, including the localization of binding sites or sequences. Here we use synthetic nanopores and nanostructured DNA molecules to directly measure the velocity profile of driven polymer translocation through synthetic nanopores. Our results reveal a two-stage behaviour in which the translocation initially slows with time before accelerating close to the end of the process. We also find distinct local velocity correlations as the DNA polymer chain passes through the nanopore. Brownian dynamics simulations show that the two-stage behaviour is associated with tension propagation, with correlations arising from the random-walk conformation in which the DNA begins.

Adsorption of Block-Polyelectrolytes on an Oppositely Charged Surface

Electrostatic interaction is widely considered to be the main driving force of the adsorption of polyelectrolytes (PEs) on an oppositely charged surface. Therefore, the alteration of charge distribution as a result of varying PE chain structures will directly affect the performance of the adsorption behaviors in the system at a certain monomer concentration. In this work, we studied the effects of chain structure (chain length, Nₘ) as well as sequence variables including charge fraction and blockiness on the adsorption behaviors of block-PEs on an oppositely charged planar surface in the salt-free system using PE-Poisson–Boltzmann equations. Due to the complicated competitions among the translational entropies of PEs and counterions, the conformational entropy of PEs, and the surface attractive interactions, we find that the adsorption amounts show rich behaviors. First, the adsorption amounts of charged ζc and neutral ζₙ monomers both show two-stage behaviors, that is, ζc and ζₙ drastically increase with Nₘ for short chains but moderately increase to an asymptotic value for relatively long chains. Second, the adsorption amounts of charged monomers show non-monotonic behaviors (increase first then decrease) with charge fraction. However, the adsorption amounts of neutral monomers monotonically decrease with charge fraction. Finally, when chain length and charge fraction are unchanged, the adsorption amounts of both neutral and charged monomers are independent of blockiness. Moreover, we find that overcharging can only appear when the bare surface charge density is low enough, while charge reversal and inversion can be observed in the entire range of the bare surface charge density with appropriate conditions. Additionally, our results indicate that the strength of charge reversal and inversion increases monotonically with chain length and charge fraction, while it changes non-monotonically with blockiness.

Helical tube triggered two-stage emission behavior for tetraphenylethene-functionalised hemicyanine dye: Better dispersion stronger fluorescence

Aggregation-induced emission (AIE) luminogens have recently received great attention for their wide applications in chemical sensors and biological probes. However, it remains a formidable challenge to render them multi-stage emission in one system. Herein, the emission of a tetraphenylethene (TPE)-functionalised hemicyanine dye (TPEBe-I) is awoken using a poly(m-phenylene diethynylene)-based helical tube (Poly-1) in aqueous buffer solution, although TPEBe-I alone shows an aggregation-caused quenching (ACQ) phenomenon due to the heavy atom effect of iodide. Upon increasing Poly-1, the dyes first dock on Poly-1 surface to form an aggregation complex via electrostatic interaction, and then intercalate into the tubular cavities of Poly-1 with a confined space in the single-molecular form. As the increase of Poly-1, the restriction of intramolecular motions of dyes changes from partial to sufficient, leading to an unusual AIE phenomenon of better dispersion stronger fluorescence. At last, the fluorescence intensity is enhanced by 160-fold. As a result, a two-stage emission behavior in a single system is achieved.

Experimental investigation on the seismic behaviour of innovative self-centring precast steel-concrete hybrid frames

An innovative self-centring precast steel-concrete hybrid (SPH) frame was proposed. The proposed SPH frame was assembled with reinforced concrete (RC) columns and prefabricated steel-concrete hybrid (PH) beams using steel end plates and high-strength bolts. The RC columns consisted of a traditional RC section and an unbonded post-tensioned (PT) screw-thread steel (STS) bar, and the PH beam was composed of two steel beam ends, a prefabricated RC beam unit and four unbonded PT strands. The self-centring ability of the structure system was mainly provided by the PT steel reinforcements; the energy dissipation capacity was mainly provided by the bolted web friction devices (WFDs) applied to the beam and the plastic deformation of the steel beam ends. To examine the seismic behaviour of this innovative structural system, cyclic tests were conducted on two SPH frames and one non-prestressed precast steel-concrete hybrid (NPH) frame. By analysing failure modes, hysteretic loops, skeleton curves, energy dissipation, displacement ductility ratios, stiffness degradation and the relative self-centring efficiency (RSE), the effects of the initial prestress, the pretorque of the high-strength bolts at the WFDs and the construction measure at the column base were thoroughly assessed. The test results indicated that the proposed noncontact oil jack prestressing technique used in the PH beams was reliable; during the testing process, gap opening and closing could be clearly observed at the interfaces between the RC beam unit and the steel beam end; the SPH frames exhibited better self-centring and energy consumption capabilities than the NPH frame; and the SPH frame exhibited a typical two-stage cyclic behaviour, namely, a self-centring stage and an energy consumption stage. In the self-centring stage (before the drift ratio of 2.0%), the SPH frame could effectively control residual deformation, and the RSE remained at approximately 85%; in the energy consumption stage (after the drift ratio of 2.0%), the SPH frame could effectively consume the absorbed energy. Based on the test results, a moment calculation method, which could distinguish the gap opening in the PH beam, was proposed, and the calculated results agreed well with the experimental results.

Physicochemical Characteristics of Cellulose Nanocrystals Derived from the Residue of Filamentous Microalga Tribonema utriculosum.

Tribonema biomass is considered promising biorefinery feedstock for the co-production of biodiesel and valuable bioproducts; however, the extraction of these useful compounds produces large amounts of algal residues, which produce increased environmental concerns. Herein, cellulose was extracted from the waste residue of T. utriculosum via alkalization and bleaching, followed by the production of high-value-added cellulose nanocrystals (CNCs) via acid hydrolysis. The hydrolysis was performed with 60% (wt%) H2SO4 at a yield of 13.31%, resulting in the generation of rod-shaped nanoparticles averaging 39.5 nm in diameter and 239.2 nm in length. The structural characterization analysis revealed that the prepared CNCs had high crystallinity (73.0%) due to the removal of non-cellulose components and amorphous regions by chemical treatment, as well as possessing good aqueous suspension stability (zeta potential = - 40.1 mV). Although the CNCs showed lower thermal stability than extracted cellulose, they spanned a broader temperature range due to two-stage degradation behaviour, with higher residue weight (16.7%). This work represents the first report on the preparation of a high-value-added industrial product, CNCs, from the filamentous microalga T. utriculosum, aiming to maximize benefits from waste algal residue reutilization.

A study on two R-phase transformations in intermediate temperature aged Ni-rich TiNiFe-based shape memory alloys

The effects of intermediate temperature aging on two-stage R-phase transformation behavior exhibited in Ti50-xNi48+xFe2 (x = 0.5 and 1.5) SMAs were investigated. In Ti48.5Ni49.5Fe2 SMA, no transformation occurred in the as solution-treated state, and B2↔R1 transformation was induced by Ti3Ni4 precipitates when the specimens were aged at 350 °C. When the specimens were aged at 450 °C, a two-stage R-phase transformation, B2↔R1 and B2↔R2, appeared. The B2↔R1 transformation, induced by Ti3Ni4 precipitates, occurred at higher temperature, whereas the B2↔R2 transformation, related to the Fe content in the matrix, occurred at lower temperature. The Ti49.5Ni48.5Fe2 SMA possesses a two-stage B2↔R2↔B19′ transformation in the as solution-treated state. When Ti49.5Ni48.5Fe2 specimens are aged at 350 °C/450 °C, R2→B19′ is suppressed and B2↔R1 appears as the aging time increases with R2↔B19′ disappearing and B2↔R1 appearing earlier when the aging temperature is higher. The two-stage R-phase transformation behavior exhibited in these two aged TiNiFe-based SMAs is a compromise between Ti3Ni4 precipitation and the decrease in Ni content and increase in Fe content in the matrix during the aging process.

Adsorption of Cadmium onto Sand-Attapulgite Cutoff Wall Backfill Media

The adsorption of Cd by sand-attapulgite cutoff wall backfill media was investigated with batch experiments for different quantities of attapulgite in the mixture (30%, 40%, 60%, and 100%; dry weight). The adsorption capacity of the media for Cd increased with the increase of attapulgite content (Ap). The change of adsorbed amount (qt) with time (t) exhibited two-stage behavior, with more than 80% of the final qt attained in the first 30 min of the experiments. The Elovich equation was the most suitable for describing the adsorption kinetics of Cd by the sand-attapulgite media. The isotherm data were best fit by the Freundlich equation. Analysis of the results indicates that cation exchange was the major adsorption mechanism. The theoretical maximum adsorption capacities (qm) of the sand-attapulgite media for Cd calculated by the Langmuir isotherm model are 6311 mg/kg (Ap = 30%), 6437 mg/kg (Ap = 40%), 6534 mg/kg (Ap = 60%), and 7034 mg/kg (Ap = 100%). The removal percentage (RP) and the distribution coefficient (Kd) of Cd decreased with the increase of the initial Cd concentration (C0) in the solution. An empirical equation for predicting Kd in terms of Ap and C0 was developed: log(Kd) = − 1.22log(C0) + 0.71Ap + 4.17 (r2 = 0.924). This equation can be used to estimate the distribution coefficient of Cd for sand-attapulgite backfill media. This will provide valuable parameters for the study of Cd transport in the sand-attapulgite cutoff wall media, and for the design of such systems for management of landfill leachate.

Effect of nanotube diameter on the transport of water molecules in electric fields

Electric fields control the water dipole orientation and result in a rotation-translation coupling transport of water through narrow carbon nanotubes (CNTs); however, it is not clear if this phenomenon still holds when the confined water is close to bulk structures for increasing the CNT diameter. Herein, we confirm that this transport phenomenon still exists for larger CNTs with bulk-like water structures. Using molecular dynamics simulations, we investigate the transport of water molecules through CNTs with different diameters in electric fields. The water flow decreases as a whole with the increase of field strength, while the water flux changes oppositely with a two-stage behavior, leading to the increase of unidirectional transport efficiency ƞ. Similar to the experimental wetting phenomenon of CNTs, our simulated water occupancy displays a linear increase with the field strength. Moreover, we find a simple equation of τ = σ*N/flow that can accurately predict the water translocation time τ according to the water occupancy N and flow, where σ is a fixed coefficient for each CNT diameter and numerically close to the ambient temperature of 300 K. The water dipole angels can be highly regulated by the electric field, as the values change from nearly 900 with random orientation to below 300 that along the field direction, which can be further elucidated by the unique dipole distributions. The water dipole orientation exists a two-stage change that accounts for the two-stage water flux behavior. These results enrich our knowledge of the transport behavior of water molecules under external fields, and are helpful for the design of stable and high-efficient nanofluidic devices.

A computational model for the evaporation of urea-water-solution droplets exposed to a hot air stream

A simple computational model was created to predict the vaporization rates of droplets of urea-water-solution (UWS) evaporating in a hot air stream. A single-component evaporation model, which was based on Abramzon-Sirignano’s vaporization model, was adapted to handle UWS droplets, and the governing equations were solved numerically in MATLAB®. The temperature and species concentrations within the droplet were assumed to be uniform, and various methods available in literature were employed to estimate important thermophysical properties such as saturation vapor pressures, partial pressures, vaporization enthalpy, and vapor diffusivities. The suitability and limitations of the computational model were assessed by comparing the results with experimental data on UWS droplets evaporating under forced convective conditions. The temperatures considered in this study ranged from 373 K to 673 K, and the corresponding relative air velocities were between 1.5 m/s and 4.3 m/s. The model was found to be able to capture the two-stage vaporization behavior of the UWS droplet (except crystallization, puffing and micro-explosion) with reasonable accuracy. While the first-stage vaporization rates, predicted by the model, were accurate to within 1.8% to 17.7%, the accuracies of the second-stage vaporization rates were significantly dependent on the methods used to estimate fluid properties such as the vapor pressures and the vaporization enthalpy.

Pinning Effect of Curie Temperature in the Sub-T <sub>g</sub> Relaxation of FeSiBPC Glasses

By combining Differential Scanning Calorimetry and in-situ high-energy synchrotron X-ray diffraction, the sub- T g relaxation of multicomponent FeSiBPC metallic glasses (MGs) has been systematically investigated. A two-stage relaxation behaviour in a series of Fe-based MGs has been observed, indicating the pinning effect of Curie temperature. The origin of this behavior resides in the local structure departure from short-range order to medium-range order upon annealing. Analysis of diffraction and thermophysical data shows that the structural ordering involved in the β relaxation is confined and, meanwhile, facilitated by the magnetic ordering. It is mainly the medium-range rearrangements of atoms that yield the influence on magnetic ordering. This work provides new insights into the interaction between structural arrangement during relaxation and intrinsic magnetic ordering and helps to understand the inner magnet-influenced β relaxation in MGs.