Mass Loss Evolution Research Articles

Experimental study of air cargo temperature variations and its impact on mango quality

An air cargo supply chain for fresh mango was investigated from Thailand to France. Measurements of air temperature, air relative humidity, and fruit (peel) temperature were conducted using thermo-hygrometer data loggers in cartons. In a Unit Load Device (ULD) containing 148 cartons, twenty-seven instrumented cartons were placed at different positions to observe spatial and temporal temperature variations during 12 h cruising. At the destination, mango quality attributes were assessed at different time-points during 15-day storage at 16.1 °C and 21.6 °C. Throughout the supply chain, fruit temperatures ranged from 16.6 °C to 30.5 °C. During cruising, fruit temperatures in upper cartons remained almost constant, whereas base carton temperatures continuously decreased from 26.1 °C to 18.1 °C. Because of a short cruising period in comparison to a storage duration at the destination and proper ambient temperature condition during the experiment, carton position in the ULD had no discernible impact on fruit quality during storage. Fruit stored at 16.1 °C preserved superior fruit quality compared to 21.6 °C storage. For the same storage temperature, better quality of fruits stored in Thailand demonstrated the impact of air shipment on product degradation. The measured temperature and relative humidity evolutions were used as input parameters of a mass loss evolution model. A comparison with the measured data exhibited good agreement (RMSE < 1.8 % mass loss). Considering 10 % mass loss as a critical value, this model allows an estimation of the product shelf life based on a supply chain scenario.

A computationally efficient statistically downscaled 100 m resolution Greenland product from the regional climate model MAR

Abstract. The Greenland Ice Sheet (GrIS) has been contributing directly to sea level rise, and this contribution is projected to accelerate over the next decades. A crucial tool for studying the evolution of surface mass loss (e.g., surface mass balance, SMB) consists of regional climate models (RCMs), which can provide current estimates and future projections of sea level rise associated with such losses. However, one of the main limitations of RCMs is the relatively coarse horizontal spatial resolution at which outputs are currently generated. Here, we report results concerning the statistical downscaling of the SMB modeled by the Modèle Atmosphérique Régional (MAR) RCM from the original spatial resolution of 6 km to 100 m building on the relationship between elevation and mass losses in Greenland. To this goal, we developed a geospatial framework that allows the parallelization of the downscaling process, a crucial aspect to increase the computational efficiency of the algorithm. Using the results obtained in the case of the SMB, surface and air temperature are assessed through the comparison of the modeled outputs with in situ and satellite measurement. The downscaled products show a considerable improvement in the case of the downscaled product with respect to the original coarse output, with the coefficient of determination (R2) increasing from 0.868 for the original MAR output to 0.935 for the SMB downscaled product. Moreover, the value of the slope and intercept of the linear regression fitting modeled and measured SMB values shifts from 0.865 for the original MAR to 1.015 for the downscaled product in the case of the slope and from the value −235 mm w.e. yr−1 (original) to −57 mm w.e. yr−1 (downscaled) in the case of the intercept, considerably improving upon results previously published in the literature.

Optical, thermal, and magnetic properties of a microporous fluorinated iron phosphate: (H3O)2[Fe4(H2O)2F4(PO4)2(HPO4)2](H2O)

AbstractThe non‐centrosymmetric microporous fluorinated iron phosphate, (H3O)2[Fe4(H2O)2F4(PO4)2(HPO4)2](H2O), is endowed with properties. In fact, the thermogravimetric analysis study shows a mass loss evolution as a temperature function. The optical study was also examined by UV–vis absorption. The magnetic results reveal the appearance of a ferromagnetic behavior at low temperature (Tc = 11.64 K).

Surface microstructure and phase structure of zirconia ceramics under intense pulsed ion beam irradiation

The surface microstructure and phase structure of zirconia (ZrO2) ceramics under intense pulsed ion beam (IPIB) irradiation were investigated in this work. Experiments were carried out on TEMP-4M accelerator with peak accelerating voltage, current density, and pulse duration of 220 kV, 150 A/cm2, and 80 ns. Micro-cracks with a height of up to 150 nm above the surface were observed and were deduced to be formed by the tensile stress during the shrinking process. The cross-sectional observation indicates that columnar structure thin layer with thickness about 1.23 μm was produced after IPIB irradiation. The GIXRD pattern indicates that obvious preferred orientation in (110) and (200) of t-ZrO2 was occurred in near-surface region after IPIB irradiation. Opposite micro-stress in bulk and near-surface region was revealed by W-H plot after Rietveld refinement. The evolution of mass loss and surface roughness of samples with pulse number was also investigated.

A reaction-diffusion framework for hydrolytic degradation of amorphous polymers based on a discrete chain scission model

Hydrolytic degradation of polymers involves the scission of long chain molecules, leading to molecular weight reduction and mass loss. The precise degradation response however depends on the scission probability of individual bonds along the polymer backbone. In particular, bonds near the chain ends are considered to be more susceptible to hydrolysis than inner bonds. In this paper, we incorporate a discrete chain scission model that can handle arbitrary bond scission probabilities within a continuum reaction-diffusion framework. Overall hydrolysis kinetics (including autocatalysis) is described independently of the chain scission model. By decoupling the description of the chain scission mechanism from kinetics, our framework enables the identification of the chain scission mechanism from molecular weight reduction and mass loss curves commonly reported in experimental degradation studies. We further propose a reduced continuum model which is better suited for large-scale simulations while retaining the predictive capability of the full discrete-continuum model. The model capability is illustrated in representative case studies based on experimental data from the literature for different materials and geometries. Statement of significanceMany models have been proposed to predict the evolution of molecular weight and mass loss in biodegradable polymers undergoing hydrolytic degradation. However, existing models remain limited in their ability to describe the degradation mechanism, autocatalytic kinetics and short chains diffusion simultaneously. Moreover, existing models often rely on empirical relations and a large number of fitting parameters. Here, we propose a conceptually simple discrete-continuum mathematical framework with a small number of parameters which all have a clear physical meaning. Model calibration against experimental data is simplified, and further provides insights into the degradation mechanisms at play, namely random scission, chain-end scission, or a combination of both. The framework can serve as a basis for future generalisations, including a description of evolving crystallinity, or other degradation mechanisms, such as thermal oxidation or photo-degradation.

Surface roughness evolution of wind turbine blade subject to rain erosion

Leading edge erosion of wind turbine blades causes roughening of the blade’s surface, leading to a reduction of energy production. This paper presents a computational model for the prediction of the roughness evolution of the blade’s surface, based on fatigue damage calculations and rain droplet impact simulations. A novel method for the calculation of material roughness due to multiple random liquid impacts was developed, by considering damage concentration in areas where sharpness due to material removal is formed. Material removal was governed by fatigue damage values. The computational model was compared to roughness measurements from a sample tested in a rain erosion tester. The outputs of this model are 3D surfaces resembling the roughness of the protective coating layer as well as the evolution of surface roughness parameters and mass loss throughout time.

Tidal Stripping of a White Dwarf by an Intermediate-mass Black Hole

During the inspiralling of a white dwarf (WD) into an intermediate-mass black hole (∼102−5 M ⊙), both gravitational waves (GWs) and electromagnetic (EM) radiation are emitted. Once the eccentric orbit’s pericenter radius approaches the tidal radius, the WD would be tidally stripped upon each pericenter passage. The accretion of this stripped mass would produce EM radiation. It is suspected that the recently discovered new types of transients, namely the quasiperiodic eruptions and the fast ultraluminous x-ray bursts, might originate from such systems. Modeling these flares requires a prediction of the amount of stripped mass from the WD and the details of the mass supply to the accretion disk. We run hydrodynamical simulations to study the orbital parameter dependence of the stripped mass. We find that our results match the analytical estimate that the stripped mass is proportional to z 5/2, where z is the excess depth by which the WD overfills its instantaneous Roche lobe at the pericenter. The corresponding fallback rate of the stripped mass is calculated, which may be useful in interpreting the individual flaring light curve in candidate EM sources. We further calculate the long-term mass-loss evolution of a WD during its inspiral and the detectability of the GW and EM signals. The EM signal from the mass-loss stage can be easily detected: the limiting distance is ∼320(M h/104 M ⊙) Mpc for the Einstein Probe. The GW signal, for space-borne detectors such as Laser Interferometer Space Antenna or TianQin, can be detected only within the Local Supercluster (∼33 Mpc).

Effect of particle characteristics, kinetics and transport phenomena on the prediction of particle mass loss and products yields during biomass fast pyrolysis

A low computational cost model for the pyrolysis of biomass anisotropic particles was used to study the effect of thermal conductivity of the particle, CRECK kinetic scheme implementation, intraparticle secondary reactions, heats of reaction, and advection on particle conversion prediction. The model considers a shrinking anisotropic cylindrical particle with biomass pseudo-components, the appearance of liquid intermediates, intra-particle mass and heat transport and secondary reactions of volatiles. The model was validated against oak and birchwood single particle experiments. More accurate predictions for mass loss evolution are found when considering the change of the particle thermal conductivity anisotropy with conversion and the temperature dependency of the thermal conductivities of the biomass and the gas phase, compared to ignoring these phenomena. The CRECK biomass pyrolysis reaction scheme provides insights into the effect of biomass composition on the evolution of the liquid intermediate phase allowing future studies about the presence of heavy compounds in the bio-oil and other phenomena such as aerosol ejection. Secondary intraparticle vapor phase reactions showed a negligible effect in volatiles conversion while heterogeneous reactions slightly overestimate its conversion. Heats of reaction and product advection are important for accurate prediction of particle mass loss.

Constitutive modelling of hydrolytic degradation in hydrogels

Biodegradable synthetic hydrogels have emerged as promising materials for tissue engineering and drug/cell delivery applications. However, their successful implementation requires precise understanding of the degradation response in terms of mechanical properties, swelling, and mass loss. In this work, we develop a thermodynamically-consistent continuum framework and constitutive models for coupled large deformation and hydrolytic degradation in hydrogels. In particular, we propose constitutive models for the evolution of elastic modulus and polymer mass loss based on a description of the evolving network topology during hydrolysis. The theory is validated against experimental data for two model hydrogel systems with different network architectures, namely biodegradable Tetra-PEG hydrogels and PLA-b-PEG-b-PLA hydrogels. We have also implemented our model in a finite element software. We show that our model is capable of simulating degradation-induced heterogeneous swelling in scenarios relevant to biomedical applications. Our theory and constitutive models could be useful for the design of hydrogels with controlled degradation behaviour.

Modelling magnetically channeled winds in 3D – I. Isothermal simulations of a magnetic O supergiant

ABSTRACT In this paper we present the first set of 3D magnetohydrodynamic (MHD) simulations performed with the riemann geomesh code. We study the dynamics of the magnetically channeled winds of magnetic massive stars in full three dimensions using a code that is uniquely suited to spherical problems. Specifically, we perform isothermal simulations of a smooth wind on a rotating star with a tilted, initially dipolar field. We compare the mass-loss, angular momentum loss, and magnetospheric dynamics of a template star (with the properties that are reminiscent of the O4 supergiant ζ Pup) over a range of rotation rates, magnetic field strengths, and magnetic tilt angles. The simulations are run up to a quasi-steady state and the results are observed to be consistent with the existing literature, showing the episodic centrifugal breakout events of the mass outflow, confined by the magnetic field loops that form the closed magnetosphere of the star. The catalogued results provide perspective on how angular-momentum loss varies for different configurations of rotation rate, magnetic field strength, and large magnetic tilt angles. In agreement with previous 2D MHD studies, we find that high magnetic confinement reduces the overall mass-loss rate, and higher rotation increases the mass-loss rate. This and future studies will be used to estimate the angular-momentum evolution, spin-down time, and mass-loss evolution of magnetic massive stars as a function of magnetic field strength, rotation rate, and dipole tilt.

A Laboratory-driven Multiscale Investigation of X-Ray Induced Mass Loss and Photochemical Evolution in Cosmic Carbon and Silicate Dust

Abstract We present the results of an integrated laboratory and modeling investigation into the impact of stellar X-rays on cosmic dust. Carbonaceous grains were prepared in a cooled (&lt;200 K) supersonic expansion from aromatic molecular precursors, and were later irradiated with 970 eV X-rays. Silicate (enstatite) grains were prepared via laser ablation, thermally annealed, and later irradiated with 500 eV X-rays. Infrared spectra of the 3.4 μm band of the carbon sample prepared with benzene revealed 84% ± 5% band area loss for an X-ray dose of 5.2 ×1023 eV.cm−2. Infrared spectra of the 8–12 μm Si–O band of the silicate sample revealed band area loss up to 63% ± 5% for doses of 2.3 × 1023 eV.cm−2. A hybrid Monte Carlo particle trajectory approach was used to model the impact of X-rays and ensuing photoelectrons, Auger and collisionally ionized electrons through the bulk. As a result of X-ray ionization and ensuing Coulomb explosions on surface molecules, the calculated mass loss is 60% for the carbonaceous sample and 46% for the silicate sample, within a factor of 2 of the IR band loss, supporting an X-ray induced mass-loss mechanism. We apply the laboratory X-ray destruction rates to estimate the lifetimes of dust grains in protoplanetary disks surrounding 1 M ⊙ and 0.1 M ⊙ G and M stars. In both cases, X-ray destruction timescales are short (a few million years) at the disk surface, but are found to be much longer than typical disk lifetimes (≳10 Myr) over the disk bulk.

Effect of Dolomite Filler on the Sulfuric Acid Resistance of Alkali-Activated Slag Binders

In this work, the influence of a dolomite filler, in combination with pulverized fly ash, on the sulfuric acid (H2SO4) resistance of alkali-activated slag (AAS) is studied. The evolution of compressive strength and mass loss, as well as mineralogical, compositional, and molecular structural alteration of hardened AAS binders containing 0%, 20%, and 40% dolomite filler, or a combination of 20% dolomite and 20% fly ash, exposed to 0% (deionized water), 1%, 2.5%, and 5% H2SO4 solutions, are investigated. The results show that the dolomite and fly ash incorporation in AAS pastes exacerbates the alkalis leaching and alkalinity loss and tends to enhance the strength loss in the H2SO4 solutions, likely due to a coarsened pore structure and, thus, enlarged permeability. Under the H2SO4 attack, AAS is decomposed into gypsum, glauberite, and amorphous calcium-magnesium aluminosilicate hydrates, with little thaumasite, ettringite, or magnesium-bearing mineral formations. While decalcification and the silica polymerization of gel products take place in AAS upon an acid attack, it has strong dealumination resistance. In low and intermediate acid concentrations, the dolomite incorporation reduces the amount of gypsum and glauberite formed in AAS due to the dilution effect, while in strong acid media, dolomite dissolution occurs and contributes to the deleterious sulfate minerals formation.

Extensive electrochemical study and surface examinations combined with DFT theoretical approaches of Zoffa extracts as green corrosion inhibitors for ASTM/A36 steels in acidic solutions

Sustainable Zoffa extract solution provides organic molecules with structures including heteroatoms, aromatic rings, and polar groups, which play an important role in the adsorption and inhibition process on metal substances in corrosive environments. The main components in Zoffa extract solution, such as phenylacetaldehyde, myrtenol, pinocamphone, and isopinocamphone, can easily be adsorbed on the ASTM/A36 steel surface and appropriately control its corrosion rate in 1 M HCl at different temperatures. The adsorption process was characterized using FTIR, UV/vis, fluorescence SEM, atomic force microscopy (AFM), and the contact-angle technique. The inhibition performance was evaluated using chemical methods, such as mass loss (ML) and hydrogen evolution (HE), and electrochemical methods, such as potentiodynamic Tafel polarization (PTP), electrochemical impedance spectroscopy (EIS), cyclic polarization sweep (CPS), and the Mott–Schottky technique (MST). The PTP explained the mixed inhibition effect of the Zoffa extract with predominantly cathodic inhibition. A Zoffa concentration of 1500 ppm provided an average inhibition protection of 94.68%. The Zoffa molecule was adsorbed on the electrode surface according to the Langmuir isotherm. Thermodynamic parameters involving E*, ΔH*, ΔS*, and ΔG* were calculated using Arrhenius and transition-state equations. The quantum parameter was theoretically estimated using the density-functional-theory method with 6-311++ G(d,p) as the basis function set to elucidate the correlation between the molecular structure of the inhibitor and its inhibition performance.

Mixture of Graphene Oxide/Phosphoric Acid/Melamine as Coating for Improved Fire Protective Performance and Enhancement of Surface Electrical Properties on Wood Chipboard.

Looking for multifunctional materials, an assessment of the performances both as fire retardant and generator of electrically conductive surfaces for a three component mixture of graphene oxide, phosphoric acid and melamine applied on wood chipboard was performed. A simple approach was used to investigate the intumescent char formation and quantify the loss mass during vertical burning tests, in which the prepared samples were exposed for a certain time interval to a flame generated by an ethanol lamp in ambient conditions. Moreover, mass loss evolution and structural changes that occur during the burning process were more comprehensive investigated by differential thermal and thermogravimetric (DTA/TGA) techniques. By comparing the performances between the wood chipboard samples without any coverage and those covered with one or multiple component mixture, an increase of protection against the fire action was noticed when the three component mixture was used. Also, an improvement of the electrical properties was observed, after flame exposure of the samples covered with multiple layers (i.e., two and three), when the three component mixture was used. Morphological and structural investigations by microscopy (optical and electronic-SEMEDX), X-ray diffraction (XRD) and spectral (Raman, FTIR) methods are described. An assessment of market potential is also discussed.

High-stress impact–abrasion test by discrete element modeling

This work presents a discrete element model (DEM) of the impeller–tumbler wear test in order to investigate high-stress impact–abrasion mechanisms on steel plates with the use of abrasive granite particles. A DEM calibration procedure of the granite particles is first performed to set particle-scale DEM parameters such as particle shape, density and frictions. The simulations of the impeller–tumbler wear test showed good qualitative results with experimental observations. Simulation results demonstrate that edges of the tested steel plate samples are first abraded, as in the experiments, and a linear increase in abrasion energies cumulated with time on the steel plates is obtained which is in accordance with the linear time evolution of sample mass loss in the experiments. Simulations shed light on the particle flow and particle–wall contact behavior which was impossible to observe experimentally. Local investigations of particle–wall contacts show an exponential decay of normal contact forces classically found for static granular materials when forces are above the mean contact force. Also, tangential contact forces distribution follows an exponential decay for forces above their mean force. This work demonstrates that the exponential decay of large contact forces is a robust feature even for a dynamic and loose granular system which is a novelty. Finally, probability density functions of normal and tangential abrasion energies are found to follow exponential decays for energy data above their mean values which is for the first time observed.

Multicomponent Pyrolysis Model for Thermogravimetric Analysis of Phenolic Ablators and Lignocellulosic Biomass

A multicomponent kinetic mechanism has been developed for the pyrolysis at low heating rate of carbon/phenolic thermal protection material and a wood species. An experimental campaign has been carried out using thermogravimetric analysis to study the mass loss under different conditions of crucible (with or without a lid) and heating rate for both materials. Using a pierced lid to cover the crucible during pyrolysis promotes char production compared with the case of open crucible. Kinetic parameters were then extracted from the experiments by an optimization approach using an in-house-developed kinetic identification code. The parameters recovered for the two applications allow to reproduce accurately the mass loss evolution.

The variable-mass seepage law of broken porous rock: an experimental study

Induced by tunnel excavation, the particles constantly shift in broken porous rock of faults until failure occurs, which provides channels for water inrush. Therefore, it is essential to investigate the particle migration of broken porous rock. Thus, a visual experimental system of particle migration was developed independently. Further study on the mass loss evolution of broken porous rock induced by seepage failure was performed using physical model tests, and the effect of the grain gradation of broken porous rock was also analyzed. According to the composition and lost characteristics of the samples, the samples were divided into dense-suspension structure and void-skeleton structure. The results indicated that the mass loss of the particles decreased with the increase in the gradation coefficient when the sample had a dense-suspension structure, while there was no significant change in the lost quality with the increase of gradation coefficient when the sample had a void-skeleton structure. Moreover, the time required for water inrush decreased with the increase in the gradation coefficient, which is because the higher the content of the fine particles is, the lower the permeability of the sample. Sample settlement is positively correlated with the lost quality of particles.

Profile of internal relative humidity and depth of drying in cementitious materials containing superabsorbent polymer and nano-silica particles

This paper aims to characterize and model the internal relative humidity profiles and drying depth in hardened cement pastes containing superabsorbent polymers (SAP) and nano-silica (NS) particles. Five different cement pastes were considered with the incorporation of SAP, NS, and simultaneous SAP and NS to reference mixtures with different water/cement ratios. Characterization of mass loss history, the evolution of the diffusion coefficient, and modeling of relative humidity profiles were performed for the five cement pastes in three different ages and three drying times. This paper also proposes a low-cost apparatus to monitor the mass loss history of thin specimens of cement pastes. The characterization was determined by the drying process with a gradual variation of the RH environment from 100% to 43%. The diffusion coefficient and the profile of the internal relative humidity through the drying depth in specimens of different ages and drying periods were estimated by the mass loss evolution. The results show that the pastes containing SAP presents a higher mass loss, higher diffusivity and deeper drying depths for all ages and drying periods investigated. Although the incorporation of NS to the reference paste improved their performance, this improvement is observed only in 28-day old pastes with SAP.

Novel platform for visualization monitoring of hydrolytic degradation of bio-degradable polymers based on aggregation-induced emission (AIE) technique

Although lots of works have been done on the hydrolysis of synthetic biodegradable polymers, the methods for monitoring the degradation process still suffer from some disadvantages, especially in terms of detection speed and non-invasive manners. In this work, a fast, non-invasive visualization monitoring platform was developed for hydrolytic degradation of bio-degradable polymers based on aggregation-induced emission (AIE) technique. We synthesized and introduced an amphiphilic AIE probe to the commercial polylactide (PLA) matrix through a simple co-precipitation process. Amphiphilic AIE probes gradually entered the aqueous media during the hydrolytic degradation process of PLA matrix, which exhibited fluorescence evolution. The variation of fluorescence emission corresponding to the evolution of PLA mass loss could be easily observed by naked eyes. Compared to traditional characterization techniques based on mass loss and molar mass measurements by sampling, this method is sensitive, fast and non-invasive, and has the potential to become a standard method for commercial bio-degradable product testing.

Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

AbstractBitumen is frequently used as energy source. To further understand bituminous combustion and emitted volatiles during its energy generation and conversion at the fraction level including saturates, aromatics, resins, and asphaltenes (SARA), an elemental analyzer, thermogravimetry coupled with mass spectrometer and Fourier‐transform infrared spectroscopy (TG‐MS‐FTIR) were utilized to monitor the mass loss evolution, and confirm molecular structures of emitted volatiles, and track the whereabouts of main elements during each SARA fraction combustion. Results indicate that TG, DTG, and Gram‐Schmidt (G‐S) curves show two‐stage characteristics, while the total ion chromatogram (TIC) curves present one‐stage characteristic during each SARA fraction combustion. Also, as the heating rate is raised, TG, DTG, TIC, and G‐S curves are shifted to higher temperature and the total emitted volatile amount is increased from saturates to asphaltenes. Molecular weights of main volatiles are distributed in the range of 12‐64. The elemental species of volatiles are consistent with those of SARA fractions. Finally, the typical volatiles of saturates and aromatics are similar, and the release amount of CO and CO2 at stage II is larger than those at stage I. SO2 is released during the combustion of resins. SO2 and NO2 are identified in volatiles of asphaltenes.