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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Preparation, Properties, and Application of Lignocellulosic-Based Fluorescent Carbon Dots

We report that carbon dots (CDs) are a relatively new type of fluorescent carbon material with excellent performance and widespread application. As the most readily available and widely distributed biomass resource, lignocellulosics are a renewable bioresource with great potential. Research into the preparation of CDs with lignocellulose (LC-CDs) has become the focus of numerous researchers. Compared with other carbon sources, lignocellulose is low cost, rich in structural variety, exhibits excellent biocompatibility, and the structures of CDs prepared by lignin, cellulose, and hemicellulose are similar. This Review summarized research progress in the preparation of CDs from lignocellulosics in recent years and reviewed traditional and new preparation methods, physical and chemical properties, optical properties, and applications of LC-CDs, providing guidance for the formation and improvement of LC-CDs. In addition, the challenges of synthesizing LC-CDs were also highlighted, including the interaction of different lignocellulose components on the formation of LC-CDs and the nucleation and growth mechanism of LC-CDs; from this, current trends and opportunities of LC-CDs were examined, and some research methods for future research were put forward.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Electrochemical Oxidation of HMF via Hydrogen Atom Transfer and Hydride Transfer on NiOOH and the Impact of NiOOH Composition

Abstract A great deal of attention has been directed toward studying the electrochemical oxidation of 5‐hydroxymethylfurfural (HMF), a molecule that can be obtained from biomass‐derived cellulose and hemicellulose, to 2,5‐furandicarboxylic acid (FDCA), a molecule that can replace the petroleum‐derived terephthalic acid in the production of widely used polymers such as polyethylene terephthalate. NiOOH is one of the best and most well studied electrocatalysts for achieving this transformation; however, the mechanism by which it does so is still poorly understood. This study quantitatively examines how two different dehydrogenation mechanisms on NiOOH impact the oxidation of HMF and its oxidation intermediates on the way to FDCA. The first mechanism is a well‐established indirect oxidation mechanism featuring chemical hydrogen atom transfer to Ni 3+ sites while the second mechanism is a newly discovered potential‐dependent (PD) oxidation mechanism involving electrochemically induced hydride transfer to Ni 4+ sites. The composition of NiOOH was also tuned to shift the potential of the Ni(OH) 2 /NiOOH redox couple and to investigate how this affects the rates of indirect and PD oxidation as well as intermediate accumulation during a constant potential electrolysis. The new insights gained by this study will allow for the rational design of more efficient electrochemical dehydrogenation catalysts.

2,5-furandicarboxylic acid↗
DOE OSTI2023

Efficient Fast Fractionation of Biomass Using a Diol-Based Deep Eutectic Solvent for Facilitating Enzymatic Hydrolysis and Obtaining High-Quality Lignin

Current DES pretreatment is often performed under relatively severe conditions with high temperature, long time, and high DES usage. This work studied a short-time diol DES (deep eutectic solvent) pretreatment under mild conditions to fractionate the bamboo, facilitate enzymatic hydrolysis, and obtain high-quality lignin. At an optimized condition of 130 °C for only 10 min, lignin and xylan removal reached 61.34% and 84.15 %, with residual glucan showing a ~90% enzymatic hydrolysis yield. Equally important, the dissolved lignin could be readily recovered with 97.51% yield, exhibiting 96.65 % β-O-4 preservation. The fractionation and lignin protection mechanisms were unveiled by XRD, FTIR, cellulose-DP, 2D HSQC NMR, 31 P NMR and GPC analysis. Finally, this study highlighted that short-time fractionation of bamboo can be achieved by a diol-based DES which is an ideal strategy to upgrade the lignocellulose biomass for high enzymatic hydrolysis yields and high-quality lignin stream.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

δ 2 H isotopic offsets in xylem water measurements under cryogenic vacuum distillation: Quantifying and correcting wood‐water hydrogen exchange influences

Stable isotopes δ 18 O and δ 2 H are used to infer vegetation water sources. In some studies, significant xylem water δ 2 H offsets from potential source waters have been observed. The offsets appear to be more prevalent with cryogenic vacuum distillation (CVD) of plant water. Hypothesized mechanisms for these offsets include changes during plant water uptake and transport, and methodological problems. We propose that a large portion of the offsets are due to hydrogen isotope exchange between xylem water and non-crystalline hydroxyl groups of wood cellulose and hemicellulose during CVD. We present a method for estimating the hypothesized isotopic exchange between wood tissues and water, which is the result of Rayleigh and equilibrium fractionation. To estimate the exchange, we use published wood properties for North American tree species and isotope chemical relationships as a function of moisture content, CVD temperature and water extraction efficiency. A simple model of exchange between xylem water and hydroxyl groups captures the range of observations in studies in which CVD and non-CVD methods were compared. To evaluate the model, we compared observed δ 2 H offsets (sw-excess) values from two field datasets (90°C, n = 364, and 170°C, n = 43) to δ 2 H offsets estimated with our chemical model. We found good agreement between observed and estimated δ 2 H offsets for samples extracted at 90°C (r 2 = 0.69) but not for samples extracted at 170°C (r 2 = 0.20). The offset may be eliminated by increasing the extraction temperature to 229°C or by adding a standard sufficient to raise the moisture content to >150%. A correction can also be approximated by applying a theoretical calculation based on the extraction temperature, moisture content and water extraction efficiency.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

No evidence of top–down effects by ants on litter decomposition in a temperate grassland

Ants play multiple roles in ecosystems, but their ability to affect decomposition processes in temperate grasslands is relatively unknown. We investigated whether the suppression of ant populations influenced litter decomposition in grasslands via predation of some decomposers (e.g., mites and springtails) and/or microbial activity and composition. We performed two successful ant suppression treatments (seven weeks, 37% suppression, year 1, 10 weeks, 70% suppression, year 2) over the course of a 59-week experiment. We then assayed the effects of ant suppression using coarse- and fine-mesh litterbags and evaluated litter chemistry, microbial and arthropod communities, and microbial enzyme activity. Ant suppression efforts reduced ant abundance and altered ant, arthropod decomposer, and non-ant predator community composition. However, ant suppression did not affect decomposer arthropod abundance, litter mass loss, microbial composition, or enzyme activity in litterbags. Litterbag mesh size did not alter microbial composition, perhaps due to a failure to exclude decomposers, as mites and springtails were more or equally abundant in fine-mesh bags. Nevertheless, mesh size did change litter chemistry, suggesting that mesh size-mediated microenvironments affect decomposition environment regardless of invertebrate exclusion. Coarse-mesh litterbags had higher concentrations of microbial sugars, lignin, and N and lower concentrations of litter C and crystalline cellulose than fine-mesh litterbags. Litterbag mesh size may alter decomposition processes irrespective of invertebrate abundance. We found no evidence that ant predation was an important driver of decomposer populations or decomposition in these systems, and we suspect redundancy at the top of the detrital food web dilutes the role of ants.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Lignin lags, leads, or limits the decomposition of litter and soil organic carbon

Lignin’s role in litter and soil organic carbon (SOC) decomposition remains contentious. Lignin decomposition was traditionally thought to increase during midstage litter decomposition, when cellulose occlusion by lignin began to limit mass loss. Alternatively, lignin decomposition could be greatest in fresh litter as a consequence of co-metabolism, and lignin might decompose faster than bulk SOC. To test these competing hypotheses, we incubated 10 forest soils with C 4 grass litter (amended with 13 C-labeled or unlabeled lignin) over 2 yr and measured soil respiration and its isotope composition. Early lignin decomposition was greatest in 5 of 10 soils, consistent with the co-metabolism hypothesis. However, lignin decomposition peaked 6–24 months later in the other five soils, consistent with the substrate-limitation hypothesis; these soils were highly acidic. Rates of lignin, litter, and SOC decomposition tended to converge over time. Cumulative lignin decomposition was never greater than SOC decomposition; lignin decomposition was significantly lower than SOC decomposition in six soils. Net nitrogen mineralization predicted lignin decomposition ratios relative to litter and SOC. Although the onset of lignin decomposition can indeed be rapid, lignin still presents a likely bottleneck in litter and SOC decomposition, meriting a reconsideration of lignin’s role in modern decomposition paradigms.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Unveiling real‐time crystallization with nucleators and thickeners for zinc nitrate hexahydrate as a phase change material

Abstract The primary challenge of salt hydrates as phase change materials (PCMs) is their high degree of supercooling (∆ T Sup ). Past studies have attempted to alleviate ∆ T Sup by incorporating nucleators possessing similar lattice structure, without a thorough analysis of the nucleator/PCM interactions. This work presents a novel in‐operando study to visually observe the crystallization process of zinc nitrate hexahydrate (ZNH) in real‐time using suitable nucleators and a thickener. We have introduced a new dataset where zinc acetate dihydrate (ZnAc.2H) has been employed as an additive to ZNH for thermal energy storage (TES). According to our in‐operando study, ZnAc.2H underwent hydrolysis in molten ZNH to precipitate needle‐like ZnO particles, which acted as nucleators for the PCM. In the absence of a thickener, the crystal propagation of ZNH exhibited a preferential directional tendency, whereas incorporation of thickener made the phase change process uniform along all directions. Self‐hydrolysis of ZnAc.2H generated excess water which caused the undesirable effect of broadening the endothermic peak. The addition of carboxymethyl cellulose (CMC) thickener could restrict the activity of excess water and reduce the broadening of the endothermic peak. Differential scanning calorimetry (DSC) revealed that 5 wt% ZnAc.2H additive and 2 wt% CMC thickener added to ZNH can considerably improve the TES properties of ZNH PCM (∆ H Fusion 125.9 J·g −1 , ∆ T Sup 3.0°C, melting point [M.P.] 29.0°C). Our in‐operando studies can unveil real‐time phase change behaviors to better design PCM systems with desired characteristics.

Chakraborty, Anirban↗
DOE OSTI2021

The Arabidopsis thaliana nucleotide sugar transporter GONST2 is a functional homolog of GONST1

Abstract Glycosylinositolphosphorylceramides (GIPCs) are the predominant lipid in the outer leaflet of the plasma membrane. Characterized GIPC glycosylation mutants have severe or lethal plant phenotypes. However, the function of the glycosylation is unclear. Previously, we characterized Arabidopsis thaliana GONST1 and showed that it was a nucleotide sugar transporter which provides GDP‐mannose for GIPC glycosylation. gonst1 has a severe growth phenotype, as well as a constitutive defense response. Here, we characterize a mutant in GONST1’s closest homolog, GONST2. The gonst2‐ 1 allele has a minor change to GIPC headgroup glycosylation. Like other reported GIPC glycosylation mutants, gonst1‐1gonst2‐1 has reduced cellulose, a cell wall polymer that is synthesized at the plasma membrane. The gonst2‐1 allele has increased resistance to a biotrophic pathogen Golovinomyces orontii but not the necrotrophic pathogen Botrytis cinerea . Expression of GONST2 under the GONST1 promoter can rescue the gonst1 phenotype, indicating that GONST2 has a similar function to GONST1 in providing GDP‐D‐Man for GIPC mannosylation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Registration of the sorghum carbon–partitioning nested association mapping (CP–NAM) population

The sorghum [ Sorghum bicolor (L.) Moench] carbon-partitioning nested association mapping (CP_NAM) (Reg. no. MP-4, NSL 542189 MAP) population was developed at Clemson University, SC, using 11 diverse, male founder accessions, each crossed with a recurrent female parent ‘Grassl’. The male parents represent all five major botanical races and the four major agronomic types: cellulosic (5), sweet (3), grain (2) and forage (1). A set of 11 recombinant inbred line (RIL) families CP_NAM01 to CP_NAM011 were maintained, which consisted of 2,484 (F 6 ) individuals. Each RIL family contained a minimum of 193 individuals (CP_NAM01) and a maximum of 287 individuals (CP_NAM06). For the development of this population, the founder lines were judiciously selected from the sorghum Bioenergy Association Panel based on carbon-partitioning phenotypes that make this population an ideal genetic resource for dissecting a wide range of agronomic and compositional traits for basic and applied research. The founder accessions of the CP_NAM were phenotypically characterized for various traits, including agronomic, biomass and related components, and additional compositional components. Each of the 11 F 6 RIL families of the CP_NAM were genotyped using genotyping-by-sequencing analysis, and 144,087 single nucleotide polymorphisms were generated for each individual. Genotypic information along with phenotypic data were used for the characterization of this population and to explore the range of phenotypes that permits the understanding of carbon-partitioning dynamics. This population is a unique resource for researchers to study a wide range of contrasting carbon-partitioning characteristics in sorghum to understand the genetic architecture underlying whole-plant carbon partitioning and allocation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Hierarchically Structured Vitrimer Biocomposites for Sustainable Manufacturing

Polymers containing dynamic covalent bonds (DCBs) exhibit thermoplastic-like flow above their topology freezing temperature (T v ) while maintaining thermoset-like properties below it, making them promising for sustainable manufacturing. However, their large-scale adoption remains limited due to challenges in accurately determining T v and achieving efficient fiber-matrix bonding in composite applications. Here, hierarchically structured epoxy-anhydride-based polyester vitrimer composites reinforced with cellulosic filaments is demonstrated, where hydroxyl groups on fiber surfaces participate directly in transesterification with the matrix. Further, this dynamic interfacial bonding delivers exceptional mechanical properties, including ≈70 MPa shear strength and >10% strain-to-failure, while enabling thermal malleability. Using a combination of nuclear magnetic resonance and nano-infrared spectroscopies, direct evidence is provided that chemical bond exchange begins well below the conventionally measured T v , supporting the hypothesis that rheologically determined T v reflects a combination of chemical exchange and frictional dynamics rather than a discrete transition. The composites demonstrate excellent processability through vacuum-assisted resin transfer molding and maintain >90% of their mechanical properties after multiple thermal reforming cycles. These findings advance both the fundamental understanding of vitrimeric transitions and the practical development of sustainable, high-performance composite materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Bioinspired Dry‐Steam Superinsulation Straw Foam

Abstract Cellulosic materials offer sustainable advantages for building energy conservation. However, their development has been hindered by reduced thermal performance, often caused by structural collapse during the transition from solution to solid. Inspired by natural goose down, a bio‐based, lightweight insulation foam derived from agricultural waste straw is presented. Through in situ synthesis, bio‐silica fibers with branched structures capable of supporting hollow silica microspheres are fabricated. After steam‐mediated processing, the resulting foam exhibit low density (95 mg cm − 3 ), high porosity (95.5%), low thermal conductivity (0.03 ± 0.003 W mK −1 ), and a cyclic compressive strength of 90 kPa at 50% strain. Owing to the synergistic microstructure formed by branched bio‐fibers and hollow silica spheres, the bio‐silica foam exhibit outstanding thermal insulation performance relative to other bio‐based foams prepared by ambient drying. A passivated insulation panel is further developed by incorporating this material as the core component, achieving a thermal conductivity of 0.0275 W mk −1 and flexural strength of 6.85 MPa. The panel demonstrated durability with stable thermal performance throughout a 60‐day outdoor test. Moreover, the bio‐silica foam shows a carbon footprint of 7.50 kgCO₂ kg −1 at 70.2 wt.% silica, highlighting its promise as a sustainable insulation solution for green buildings.

Chemistry↗
DOE OSTI2023

Spectroscopic and Chemical Properties of Ionic Liquids: Computational Study

A brief account is given of highlights of our computational efforts – often in collaboration with experimental groups – to understand spectroscopic and chemical properties of ionic liquids (ILs). Molecular dynamics, including their inhomogeneous character, responsible for key spectral features observed in dielectric absorption, infra-red (IR) and fluorescence correlation spectroscopy (FCS) measurements are elucidated. Mechanisms of chemical processes involving imidazolium-based ILs are illustrated for CO 2 capture and related reactions, transesterification of cellulose, and Au nanocluster-catalyzed Suzuki cross-coupling reaction with attention paid to differing roles of IL ions. A comparison with experiments is also made.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Transgenic Sugarcane–Oilcane: An Alternative Feedstock for the Production of Drop-in Fuel and Value-Added Bioproducts

The utilization of plants and other agricultural produce can partly offset petroleum dependency for energy requirements and can potentially provide sustainable solutions to global environmental problems. To this end, synthetic biology has shown great potential in developing transgenic bioenergy grasses such as sugarcane, sorghum, miscanthus, and energy cane that hyperaccumulate energy-rich lipid molecules in their vegetative tissues, such as leaves, stems, and roots. These perennial high-biomass transgenic C4 grasses are not targeted to grow on prime agricultural land and can be dedicatedly used to produce biofuels and other value-added bioproducts. Recently, sugarcane has been metabolically engineered to sequestrate carbon from juice towards biosynthesis of lipid molecules in the vegetative tissues. Transgenic sugarcane is referred to as “oilcane.” Transgenic sugarcane–oilcane has improved energy density due to an elevated lipid content in the vegetative tissues. Transgenic bioenergy crops cater to both cellulosic sugars and vegetative lipids, hence resulting in higher biofuel yield (biodiesel/renewable diesel and bioethanol) per unit area of cultivable land. In this book chapter, the genetic engineering of sugarcane and its bioprocessing are discussed to illustrate its development and use as an alternative feedstock for the production of biofuels (bio-jet fuel, biodiesel, and bioethanol) and value-added bioproducts.

Maitra, Shraddha↗
DOE OSTI2024

Dissimilar material joining of densified superwood to aluminum by adhesive bonding

Abstract Superwood is a densified wood product that shows promise as a lightweight and renewable alternative for metallic materials. In order for this high-performance new material to be used in multi-material products, it must be able to be joined with other major materials. For example, joining superwood to aluminum would provide a key enabling technology for its use in automotive components since aluminum is presently a major lightweight material for such applications. In this paper, a methacrylate-based adhesive has been identified to provide high lap shear strength (7.5 MPa) for aluminum-to-superwood joints. The aluminum-to-superwood samples were prepared with different amounts of pre-polishing to create openings to the pores in the superwood so adhesive could penetrate into them and create a mechanical interlock, in addition to the hydrogen/chemical bonding at the surface between the methyl methacrylate (MMA) in methacrylate-based adhesive and the cellulose in superwood. For aluminum samples, a thin layer (typically a few nanometers) of oxide film on the surfaces provides hydrogen/chemical bond to MMA structure in the adhesive layer. The failure strength of the superwood-to-aluminum joint sample is about 50% higher than that of natural wood to natural wood joint sample and comparable to that of aluminum-to-aluminum joint sample.

Automation & Control Systems↗
DOE OSTI2020

Deconstruction of plant biomass by a Cellulomonas strain isolated from an ultra-basic (lignin-stripping) spring

Plant material falling into the ultra-basic (pH 11.5-11.9) springs within The Cedars, an actively serpentinizing site in Sonoma County, California, is subject to conditions that mimic the industrial pretreatment of lignocellulosic biomass for biofuel production. In this research, we sought to obtain hemicellulolytic/cellulolytic bacteria from The Cedars springs that are capable of withstanding the extreme alkaline conditions wherein calcium hydroxide-rich water removes lignin, making cell wall polysaccharides more accessible to microorganisms and their enzymes. We enriched for such bacteria by adding plant debris from the springs into a synthetic alkaline medium with ground tissue of the biofuel crop switchgrass (Panicum virgatum L.) as the sole source of carbon. From the enrichment culture we isolated the facultative anaerobic bacterium Cellulomonas sp. strain FA1 (NBRC 114238), which tolerates high pH and catabolizes the major plant cell wall-associated polysaccharides cellulose, pectin, and hemicellulose. Strain FA1 in monoculture colonized the plant material and degraded switchgrass at a faster rate than the community from which it was derived. Cells of strain FA1 could be acclimated through subculturing to grow at a maximal concentration of 13.4% ethanol. A strain FA1-encoded β-1, 4-endoxylanase expressed in E. coli was active at a broad pH range, displaying near maximal activity at pH 6-9. Discovery of this bacterium illustrates the value of extreme alkaline springs in the search for microorganisms with potential for consolidated bioprocessing of plant biomass to biofuels and other valuable bio-inspired products.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Structure and enzymatic characterization of CelD endoglucanase from the anaerobic fungus Piromyces finnis

Anaerobic fungi found in the guts of large herbivores are prolific biomass degraders whose genomes harbor a wealth of carbohydrate-active enzymes (CAZymes), of which only a handful are structurally or biochemically characterized. Here, we report the structure and kinetic rate parameters for a glycoside hydrolase (GH) family 5 subfamily 4 enzyme (CelD) from Piromyces finnis, a modular, cellulosome-incorporated endoglucanase that possesses three GH5 domains followed by two C-terminal fungal dockerin domains (double dockerin). We present the crystal structures of an apo wild-type CelD GH5 catalytic domain and its inactive E154A mutant in complex with cellotriose at 2.5 and 1.8 Å resolution, respectively, finding the CelD GH5 catalytic domain adopts the (β/α) 8 -barrel fold common to many GH5 enzymes. Structural superimposition of the apo wild-type structure with the E154A mutant-cellotriose complex supports a catalytic mechanism in which the E154 carboxylate side chain acts as an acid/base and E278 acts as a complementary nucleophile. Further analysis of the cellotriose binding pocket highlights a binding groove lined with conserved aromatic amino acids that when docked with larger cellulose oligomers is capable of binding seven glucose units and accommodating branched glucan substrates. Activity analyses confirm P. finnis CelD can hydrolyze mixed linkage glucan and xyloglucan, as well as carboxymethylcellulose (CMC). Measured kinetic parameters show the P. finnis CelD GH5 catalytic domain has CMC endoglucanase activity comparable to other fungal endoglucanases with k cat = 6.0 ± 0.6 s –1 and K m = 7.6 ± 2.1 g/L CMC. Enzyme kinetics were unperturbed by the addition or removal of the native C-terminal dockerin domains as well as the addition of a non-native N-terminal dockerin, suggesting strict modularity among the domains of CelD.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Microfibril orientation and compositional heterogeneity in fiber and vessel cell walls of poplar xylem studied by AFM-IR and SFG spectroscopy

Understanding the structural organization of cellulose microfibrils (CMFs) within individual plant cell walls is essential for connecting cell wall architecture to its mechanical and physiological functions. However, due to the complex hierarchical structure and nanoscale heterogeneity of cell walls, it remains technically challenging to resolve detailed compositional and orientational information at subcellular levels of individual cell walls. This study investigates the internal 3D structure, chemical composition, and sublayer organization of fiber and vessel cell walls in the xylem tissue of a two-year-old field-grown hybrid poplar tree (Populus alba × P. glandulosa) using photothermal atomic force microscopy coupled with infrared spectroscopy (AFM-IR) and sum frequency generation (SFG) hyperspectral microscopy. AFM-IR provided nanoscale chemical imaging, revealing localized compositional heterogeneity, including variations between adjacent cell walls and transitional layers beyond the traditional S1, S2, and S3 sublayers. SFG microscopy revealed that CMFs in fiber walls are highly aligned along the stem axis, consistent with their role in mechanical support, while vessel cell walls exhibited slightly tilted CMFs, reflecting their function in hydraulic transport. Together, these results offer new insights into cell-type-specific CMF organization and compositional gradients in hybrid poplar xylem. These findings highlight the structural and chemical complexity of secondary cell walls in woody plants and demonstrate the value of AFM-IR and SFG spectroscopy in elucidating plant cell wall architecture.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Discrete element model for powder grain interactions under high compressive stress

A reduced order, nonlocal model is proposed for the contact force between initially spherical particles under compression. The model in effect provides the normal component of the interaction force between elements in the discrete element method (DEM). It is applicable to high relative density and large stress in powder compaction. It takes into account the mutual interaction between multiple points of contact, in contrast to the usual assumption in DEM of pair interactions. The mathematical form of the model is derived from a variational formulation that leads to the momentum balance for the forces on each grain. The model is calibrated mainly using detailed three dimensional peridynamic simulations of single grains under compressive loading by rigid plates that move radially with prescribed velocity. This calibration takes into account the large deformation and fracture of the grains. The interaction model also includes terms for the unloading behavior and adhesion. Finally, as validation, the model is applied to test data on the compaction of microcrystalline cellulose bulk powder.

36 MATERIALS SCIENCE↗