High Solid Content Research Articles

Effect of Deflocculant Addition on Energy Savings in Hydrotransport in the Lime Production Process

The subject of the research was limestone hydromixture consisting of particles of a mean size of 45.5 μm conveyed by water in a pipeline of a total length of 632 m. In the paper, the results of rheological measurements of tested hydromixtures after the application of deflocculant consisting of waste product from the lime production process in the form of mineral particles and commonly known dispersant were presented. Calculations of pressure drop including hydromixtures with volume concentrations in the range of 21.30–50.00%, and density ranging from 1140–1410 kg/m3 in a pipeline of 200 mm diameter are presented. A decrease in friction losses in the flow in the pipeline of hydromixtures with different mass concentrations after the addition of deflocculant was observed. The study revealed that the addition of deflocculant resulted in a reduction of friction in the pipeline, enabling the pumping of hydromixtures with twice higher solids concentrations than originated from industrial installation, with a lower volumetric flow rate. This resulted in a decrease of the power consumption of the motor driving the pump, and obtained significant energy savings in the hydromixture transport process. The maximum energy saving achieved was equal to 58%.

Rheological properties of concentrated allophane, halloysite, and kaolinite suspensions

This study investigated the rheological properties of concentrated suspensions of allophane, halloysite, and kaolinite, which are representative of a series of weathering products of volcanic glass and feldspar minerals in volcanic rocks and deposits, to elucidate the mechanism of landslide generation involving these materials. All suspensions generally showed shear thinning during flow curve measurements, as represented by a steady decrease of viscosity with increasing shear strain rate from 0.1 to 1000 s−1. A difference among them was that the kaolinite suspension showed unstable flow behavior at high solid concentration, and the halloysite suspension had a similar behavior at low solid concentration. The shear stress at the beginning of flow—which represents the yield stress of the suspension—showed a power law correlation with the solid volumetric fraction, and that for kaolinite agreed well with previous static yield stress measurements. The stress of the halloysite suspension deviated from the power law curve at solid fraction < ~0.15. Dynamic viscoelasticity tests indicated that all suspensions showed a power law correlation between the modulus value and solid fraction. The crossover strain (when a solidlike-to-liquidlike transition occurs) of the kaolinite suspension was almost constant within the investigated solid fraction range, whereas that of the halloysite suspension decreased noticeably at solid fraction < ~0.15. Overall, the allophane suspension had the weakest strength and lowest resistance to oscillatory strain at a given solid fraction condition. The rheological properties of halloysite observed here may be related to the occurrence of flow-like, long-distance landslides in volcanic areas containing weathered tephra.

In Situ Measurement Method Based on Edge Detection and Superpixel for Crystallization Imaging at High-Solid Concentrations

To facilitate measuring crystal sizes during batch crystallization at high-solid concentrations by using an invasive imaging system, an in situ imaging measurement strategy based on edge detection and superpixel is proposed for the ambiguous boundary problem of large amounts of crystals. Firstly, an image filtering is employed to cope with image degradation caused by noise disturbance and suspension turbulence in the crystallizer. Subsequently, an image segmentation method is developed by utilizing improved edge detection and superpixel, which can be easily performed for crystal extraction. Accordingly, crystal size measurement can be developed for evaluation of the crystal size distribution. The experiment results on α-form L-glutamic acid present the effectiveness of the proposed method.

Shear properties and water connectivity of wet granules at high solid content concentration

The inner liquid distribution in wet granules strongly influences their mechanical properties. In this study, we examined the shear properties (internal friction angle, cohesion, storage modulus and loss modulus) of wet granules composed of graphite particles and water, and determined their inner water connectivity using X-ray refraction contrast imaging computed tomography (CT) to elucidate their correlation. At high solid content concentration (CSC) region (CSC = 85 wt.%), internal friction angle of wet granules was slightly lower than that of wet granules with lower CSC, and their cohesion becomes almost zero. Furthermore, storage modulus of wet granules at CSC = 85 wt.% was the highest among all wet granules. The X-ray CT and scanning electron microscopy (SEM) observations revealed that the water connectivity in the wet granules was in the pendular state and graphite particles fractured under shear test at CSC = 85 wt.%. From these results, it can be concluded that lower shear cohesion at CSC = 85 wt.% is caused by an increase in the number of isolated liquid bridges, and particle fracture results in a decrease in the internal friction angle owing to decreasing roughness of shear plane. Furthermore, the particle fracture also resulted in the higher storage modulus at CSC = 85 wt.% in rheological measurements.

Performance evaluation of an industrial ceramic nanofiltration unit for wastewater treatment in oil production

An industrial ceramic nanofiltration membrane (pore size 0.9 nm) was tested in a Canadian oil field for more than 12,500 h to treat wastewater directly from daily operations, without any type of pre-treatment. This wastewater contained a high content of total suspended solids (13 to 510 mg/kg), and total organic carbon (31 to 134 mg/kg). The membrane unit was operated at different transmembrane pressure (TMP) set points (4–16 bar) and recovery set points (40–80%). The data show that ion and compound rejection depend strongly on a combination of both TMP and recovery, with the largest rejection occurring at low recovery values and high TMP values. Two mechanisms were responsible for rejection: sieving, which mostly impacted compound rejection, and electrostatic phenomena that impacted ion rejection. It is shown that ion rejection depends linearly on charge density of the ion. Ion rejection was measured as high as 85% and compounds (such as TSS) were rejected as high as 100%. The specific flux varied between 1–10 L/(m2.h.bar). Results from this field testing indicate the possibility of using these types of ceramic membranes for oil field wastewater treatment.

Effluent recirculation weakens the hydrolysis of high-solid content feeds in upflow anaerobic sludge blanket reactors

Effluent recirculation in an upflow anaerobic sludge blanket (UASB) reactor is a commonly used strategy to improve both mixing and upflow velocity of the reactor. This study aimed to assess the impact of effluent recirculation on methane production of UASB reactors treating substrates of different solid contents. Two 2.0 L UASB reactors were operated for 219 d under mesophilic conditions. When the UASB reactors were fed with a high-solid content substrate, effluent recirculation led to significantly reduced methanisation rate (from 47.9% without recirculation to 25.5% with recirculation) and hydrolysis efficiency of particulate organic matter (from 45.5% without recirculation to 22% with recirculation). In comparison to the high-solid content substrate, a low-solid content substrate led to an increase in methanisation rate for both UASB reactors with and without effluent recirculation, but the difference in methane production for the two reactors reduced significantly. Results demonstrated that the lower methane production in the presence of effluent recirculation arose from the inefficient hydrolysis of particulate organic matter, which was mitigated when the reactors were fed with a low-solid content substrate. Turbulence due to effluent recirculation enhanced biomass transport but limited the accessibility of adsorption sites on particulate matter. An insufficient attachment between microorganisms/enzymes and particles could have lowered the hydrolysis efficiency of particulate organic matter.

Studies on pre-treatment by compression for wood impregnation III: effects of the solid content of low-molecular-weight phenol formaldehyde resin on the impregnation

There is increasing interests in the significant improvement of impregnation amount and efficiency in wood by the pre-treatment of compression. Thus, attention is paid to pre-treatment by compression for harder impregnation with resin because of the large viscosity and relatively large molecular weight of the resin. Low-molecular-weight phenol formaldehyde (PF) resin of solid content of 10–48% were impregnated by pre-treatment of compression at a compression ratio of 60% and 40% for poplar and Chinese fir, respectively, to systematically study the effects of solid content on the impregnation amount, weight gain percentage (WGP). In addition, the distribution of resin in wood was analyzed by profile density and was observed by confocal laser scanning microscope (CLSM), and the change of crystallinity index (CrI) of resin-impregnated wood was investigated by X-ray diffractometer. The results showed: (1) compared with immersion impregnation without compression, the impregnation by pre-treatment of compression, was much larger in amount and higher in efficiency for resins in all solid contents. In a solid content range of 10–48% and at a molecular weight of about 517, there was no significant difference of impregnation amount by compression among the resins at different solid content. (2) The WGP of poplar and Chinese fir increased with the increase of resin solid content. When the resin solid content increased from 10 to 48%, the WGP increased from 8.9 to 44.2% and from 5.2 to 24.9% for poplar and Chinese fir, respectively. (3) Resin is mainly distributed in vessels and tracheids despite a few being distributed in the fiber near the longitudinal end of the poplar specimens. With the increase of solid content, the resin distribution gradually changed from diffusing on the wall to depositing in the vessel or tracheid, while the resin distribution evenness along the longitudinal direction decreased. There was more resin deposited near the longitudinal end of Chinese fir at deeper depth than that of poplar. (4) The resin can be impregnated into the amorphous area of wood without causing any change in the crystallization area. The CrI decreases with the increase of resin solid content. After all, it is concluded that the pre-treatment by compression for wood impregnation with low-molecular-weight PF resin is effective for all the solid contents for both poplar and Chinese fir. The WGP increased with the increase of resin solid content, despite the decrease of evenness of resin distribution at high solid content.

Flow loop provides new insights on viscosity of drilling fluid dispersions

Power law parameters and custom design allow for better modeling of pressure drops and bore wall failure at higher concentrations of solids.

Wastewater Surveillance of SARS-CoV-2 at a Canadian University Campus and the Impact of Wastewater Characteristics on Viral RNA Detection.

Because of the increased population density, high-risk behavior of young students, and lower vaccination rates, university campuses are considered hot spots for COVID-19 transmission. This study monitored the SARS-CoV-2 RNA levels in the wastewater of a Canadian university campus for a year to provide actionable information to safely manage COVID-19 on campus. Wastewater samples were collected from the campus sewer and residence buildings to identify changes, peaks, and hotspots and search for associations with campus events, social gatherings, long weekends, and holidays. Furthermore, the impact of wastewater parameters (total solids, volatile solids, temperature, pH, turbidity, and UV absorbance) on SARS-CoV-2 detection was investigated, and the efficiency of ultrafiltration and centrifugation concentration methods were compared. RT-qPCR was used for detecting SARS-CoV-2 RNA. Wastewater signals largely correlated positively with the clinically confirmed COVID-19 cases on campus. Long weekends and holidays were often followed by increased viral signals, and the implementation of lockdowns quickly decreased the case numbers. In spite of online teaching and restricted access to campus, the university represented a microcosm of the city and mirrored the same trends. Results indicated that the centrifugation concentration method was more sensitive for wastewater with high solids content and that the ultrafiltration concentration method was more sensitive for wastewater with low solids content. Wastewater characteristics collected from the buildings and the campus sewer were different. Statistical analysis was performed to manifest the observations. Overall, wastewater surveillance provided actionable information and was also able to bring high-risk factors and events to the attention of decision-makers, enabling timely corrective measures.

Self-ball milling strategy to construct high-entropy oxide coated LiNi0.8Co0.1Mn0.1O2 with enhanced electrochemical performance

High-entropy oxides (HEOs) are a new class of emerging materials with fascinating properties (such as structural stability, tensile strength, and corrosion resistance). High-entropy oxide coated Ni-rich cathode materials have great potential to improve the electrochemical performance. Here, we present a facile self-ball milling method to obtain (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (HEO) coated LiNi0.8Co0.1Mn0.1O2 (NCM811). The HEO coating endows NCM811 with a stable surface, reduces the contact with the external environment (air and electrolyte), and inhibits side reactions between cathode and electrolyte. These favorable effects, especially when the coating amount is 5 wt%, result in a significant reduction of the battery polarization and an increase in the capacity retention from 57.3% (NCM811) to 74.2% (5HEO-NCM811) after 300 cycles at 1 C (1 C = 200 mA·h·g−1). Moreover, the morphology and spectroscopy analysis after the cycles confirmed the inhibitory effect of the HEO coating on electrolyte decomposition, which is important for the cycle life. Surprisingly, HEO coating reduces the viscosity of slurry by 37%–38% and significantly improves the flowability of the slurry with high solid content. This strategy confirms the feasibility of HEO-modified Ni-rich cathode materials and provides a new idea for the design of high-performance cathode materials for Li-ion batteries.

Dispersion polymerization of styrene/acrylonitrile in polyether stabilized by macro-RAFT agents

A series of poly(acrylate polyether)s (RPA) was designed and synthesized by reversible addition-fragmentation chain transfer (RAFT) copolymerization, which were then used as dispersants for the dispersion copolymerization of styrene/acrylonitrile in polyethers in a semicontinuous approach to prepare graft polyether polyol (POP) with high solid content. The effects of structure, dosage, and feed ratio for macro-RAFT agent RPA on the stability, viscosity, and particle size of POP were examined and discussed. The dispersion polymerization process was also characterized by gradient elution polymer chromatography, and the results indicated that RPA was rapidly consumed and block-type stabilizer formed in the initial stage of polymerization. A portion of RPA added with monomer feeding provided better stability for the semicontinuous polymerization process.

Structure-Controlled Porous Cordierite Ceramics with High Solid Content Prepared by Pickering Emulsion Technique Using Sucrose as a Porogen.

Porous cordierite ceramics (PCCs) with stable 3D microstructures were prepared by Pickering emulsion technique using sucrose as a porogen. The microstructural and mechanical properties could be adjusted by varying O/S ratios, sintering temperature, and sucrose content. The formation of the spherical structure was due to the broken oil bubbles. The appearance of cordierite and the concurrent consumption of sucrose were responsible for the observation of gradient pore structure. When the O/S ratio was 2, the pore-structure-controlled PCCs with cordierite as the main phase was obtained after sintering at 1300 °C. With the addition of 30 wt.% of sucrose, the obtained PCCs possessed high solid content of 45 vol.%, the porosity of 90.83%, the compressive strength of 6.09 MPa, and the optimized thermal conductivity of 0.4794 W/m.K. Compared with the predecessors’ research results, the as-prepared precursor of PCCs with sucrose content had the lowest initial Zeta potential without adjusting the pH to ensure the stable suspension. Our results showed that the addition of sucrose not only acts as a solvent to increase the solid content, but also acts as a pH modifier to maintain precursor stability, which enables the increase in compressive strength. In this work, via the scenario of “oil droplet” 3D accumulation, the stable and orderly spatial arrangement of the micro-emulsion system was successfully realized to obtain the structure-controlled PCCs by controlling the precursor conditions.

Differentiating Semi-Volatile and Solid Particle Events Using Low-Cost Lung-Deposited Surface Area and Black Carbon Sensors

Low-cost particle sensors have proven useful in applications such as source apportionment, health, and reactivity studies. The benefits of these instruments increase when used in parallel, as exemplified with a 3-month long deployment in an urban background site. Using two lung-deposited surface area (LDSA) instruments, a low-cost method was developed to assess the solid component of an aerosol by applying a catalytic stripper to the inlet stream of one LDSA instrument, resulting in only the solid fraction of the sample being measured (LDSAc). To determine the semi-volatile fraction of the sample, the LDSAC was compared to the LDSA without a catalytic stripper, thus measuring all particles (LDSAN). The ratio of LDSA (LDSAC/LDSAN) was used to assess the fraction of solid and semi-volatile particles within a sample. Here, a low ratio represents a high fraction of semi-volatile particles, with a high ratio indicating a high fraction of solid particles. During the 3-month urban background study in Birmingham, UK, it is shown that the LDSA ratios ranged from 0.2–0.95 indicating a wide variation in sources and subsequent semi-volatile fraction of particles. A black carbon (BC) instrument was used to provide a low-cost measure of LDSA to BC ratio. Comparatively, the LDSA to BC ratios obtained using low-cost sensors showed similar results to high-cost analyses for urban environments. During a high LDSAC/LDSAN ratio sampling period, representing high solid particle concentrations, an LDSA to BC probability distribution was shown to be multimodal, reflecting urban LDSA to BC ratio distributions measured with laboratory-grade instrumentation. Here, a low-cost approach for data analyses presents insight on particle characteristics and insight into PM composition and size, useful in source apportionment, health, and atmospheric studies.

Preparation and characterization of natamycin-incorporated agar film and its application on preservation of strawberries

This study investigated the preparation and characterization of Natamycin-incorporated agar film and its antimicrobial effect on preserve quality of fresh strawberries. Natamycin-incorporated agar films were prepared by solvent casting method and characterized in mechanical, optical, water swelling, and barrier properties. Antimicrobial activity of the films and their preservative effects on strawberries stored at 4 °C and 20 °C were also assessed. As natamycin amount increased (0%, 0.33%, 0.66%, 0.99%, 1.33%, w/w of dry film), the antimicrobial activity of the film increased with inhibition zone of Aspergillus niger and Saccharomyces cerevisiae from 0 cm to approximate 28 cm, while there was no significant effect on water vapor permeability and swelling degree. On the other hand, with the increase of natamycin, tensile strength of the film declined (from 17.61 to 14.94 MPa), while oxygen permeability enhanced from 0.161 to 0.585 × 10−15 cm3 cm/cm2 s Pa. Furthermore, the natamycin can be released quickly from antimicrobial films within 2 days under aqueous solution in accordance with fick’s law. Along with the addition of natamycin, light transmittance of antimicrobial films trends to decrease whereas the haze and total color difference of film increase significantly. Compared to control group, fungal colony number of strawberry packaged in antimicrobial film was reduced by 0.51 and 1.05 log cfu g−1 at 4 °C and 20 °C, respectively. The strawberries packaged by antimicrobial film retained high total soluble solid content with higher hardness of 61.89% and 54.47% at 4 °C and 20 °C, respectively at the end of storage. Moreover, strawberries packaged with the natamycin-incorporated film showed lower rate of water loss during storage (1.43% and 7.66% at 4 °C and 20 °C, respectively). The obtained results indicate that natamycin-incorporated agar film could be used as environment-friendly packaging alternative to preserve perishable fresh produce and extend their shelf lives by means of antimicrobial activity and other merits.

Characterising sedimentation velocity of primary waste water solids and effluents

Sedimentation in waste water is a heavily studied topic, but mainly focused on hindered and compression settling in secondary sludge, a largely monodispersed solids, where bulk sedimentation velocity is effectively described by functions such as double Vesilind (Takacs). However, many waste water solids, including primary sludge and anaerobic digester effluent are polydispersed, for which application of velocity functions is not well understood. These systems are also subject to large concentration gradients, and poor availability of settling velocity functions has limited design and computational fluid dynamic (CFD) analysis of these units. In this work, we assess the use of various sedimentation functions in single and multi-dimensional domains, comparing model results against multiple batch settling tests at a range of high and low concentrations. Both solids concentration and sludge bed height (interface) over time are measured and compared. The method incorporates uncertainty analysis using Monte Carlo regression, DIRECT (dividing rectangles), and Newton optimisation. It was identified that a double Vesilind (Takacs) model was most effective in the dilute regime (<1%v/v), but could not effectively fit high solids concentrations (>1%v/v) without a substantial (50%) decrease in effective maximum sedimentation velocity (V0). Other parameters (Rh, Rp) did not change. A power law velocity model (Diehl) was significantly less predictive at low concentrations, and not significantly better at higher concentrations. The optimised model (with reduction in V0) was tested vs a standard (optimised) double Vesilind velocity model in a simple primary sedimentation unit, and resulted in deviation from -12% to +18% in solids capture prediction from underload to overload (washout) conditions, indicating that the effect is important in CFD based analysis of these systems.

Bioinspired Hydrogel Anchoring 3DP GelMA/HAp Scaffolds Accelerates Bone Reconstruction

Seeking high biological activity and osteoinductive ability has always been an urgent problem for three-dimensional-printed (3DP) bony implants. Here, a 3DP methacrylic anhydride-modified gelatin (GelMA)/hydroxyapatite (HAp) scaffold with a high solid content of 82.5% was prepared and anchored by a functionalized polyphenol hydrogel. The scaffold and hydrogel were organically integrated into a bioinspired bony implant (HGH) by phenolic hydroxyl of hyaluronan derivatives conjugating amino groups of collagen I and GelMA and further chelating calcium ions of HAp. Compared with a simplex 3DP scaffold, this freeze-dried HGH presented better water retention, delayed degradation, and mechanical stability. It could promote migration, proliferation, and osteogenic differentiation of bone marrow stem cells in vitro. One week of implantation showed that it promoted directional migration of endogenous stem cells and early osteogenesis and angiogenesis. After 15 week surgery of rabbit skull defects, the BV/TV value of HGH returned to 73% of the normal group level. This strategy provided a new research idea for bone regeneration.

Enhancement of Biogas Production Through Solid-State Anaerobic Co-Digestion of Food Waste and Corn Cobs

Although biogas has been primarily produced through liquid anaerobic digestion, this method leads to the floating and stratification of fibers and non-homogeneous mixing, which can reduce the biogas yield. Alternatively, biogas can be produced by the solid-state anaerobic digestion (SS-AD) of organic material with a high solid content, such as corn cobs. We investigated the co-digestion of food waste and corn cobs as a biomass feedstock for SS-AD in biogas production. We measured the effects of the total solid (TS) content, percentage of food waste, and reduction in volatile solids (VS), from which we determined its appropriate kinetic model. We found that the SS-AD of food waste with corn cobs produced a high biogas yield of 543 mL/g VS at a TS content of 22% and a food waste content of 20%. The first-order kinetics model for biogas production during SS-AD of the tested corn cob and food waste yielded an R2 value in the range of 0.91–0.94. The main contributor to the biogas production during the SS-AD of the corn cobs and food waste was the reduction in VS. A positive linear relationship was observed between the biogas yield and the reduction of VS.

Sawdust as a filtering media in sludge drying beds

Conventional wastewater treatment is a common method of domestic wastewater treatment in Sub Saharan Africa. Lubigi wastewater treatment plant (LSTP) in Kampala – Uganda is a unique wastewater treatment system combining treatment of on-site faecal sludge and domestic wastewater. High solids content of on-site faecal sludge mean large volumes of the same, thus limited sludge drying space. This means need to optimize sludge drying bed use (improving the sludge drying efficiency) by reducing their drying times. This study investigated use of wood sawdust as a filtering layer in the faecal sludge drying process. Comparison of performance between sand, fine and coarse sawdust as a filtering media was conducted at LSTP. Sludge shrinkage depth (cm) and moisture content (%) were key parameters used to analyze and determine the most ideal media for sludge dewatering. The study was conducted during both wet and dry seasons to determine the impact of seasonal changes. Dry season results showed a drastic decrease in the sludge depth (shrinkage) for all the three media types after a period of 8 days followed by a gradual decrease in sludge depth up to 28 days. This implies that effective dewatering happens for the first 8 days, which goes on for the rest of the remaining days. Overall, the best performing media was fine sawdust, coarse sawdust and lastly sand. Independent two sample t-tests assuming equal variances show that there is a significant difference between the mean sludge depth of sand and fine sawdust t(df) = 56, P&lt;0.05). There was no significant difference in the mean sludge shrinkage depth of fine sawdust and coarse sawdust. Similar results were obtained during the wet season. Comparisons of similar media types during the dry and wet seasons shows that the mean sludge shrinkage for the dry season were significantly lower than that of the wet season (P&lt;0.05). This implies that seasonal changes significantly affect the sludge dewatering. In terms of moisture content (MC), the results for dry season showed that fresh fine and fresh coarse wood sawdust achieved MC of 28% and 31% respectively after 28 days. Sand produced faecal sludge with a higher MC of 49% after 28 days. Similar results of the performance of the three types of media was observed during the wet season. In conclusion, fine sawdust performs better than coarse sawdust and sand media in faecal sludge dewatering. Sludge dewatering is affected by seasonal changes.

How debris‐flow composition affects bed erosion quantity and mechanisms: An experimental assessment

AbstractUnderstanding erosion and entrainment of material by debris flows is essential for predicting and modelling debris‐flow volume growth and hazard potential. Recent advances in field, laboratory and modelling studies have distilled two driving forces behind debris‐flow erosion: impact and shear forces. How erosion and these forces depend on debris‐flow composition and interact remains unclear. Here, we experimentally investigate the effects of debris‐flow composition and volume on erosion processes in a small‐scale flume with a loosely packed bed. We quantify the effects of gravel, clay and solid fraction in the debris flow on bed erosion. Erosion increased linearly with gravel fraction and volume, and decreased with increasing solid fraction. Erosion was maximal around a volumetric clay fraction of 0.075 (fraction of the total solid volume). Under varying gravel fractions and flow volumes erosion was positively related to both impact and shear forces, while these forces themselves are also correlated. Results further show that internal dynamics driving the debris flows, quantified by Bagnold and Savage numbers, correlate with erosional processes and quantity. Impact forces became increasingly important for bed erosion with increasing grain size. The experiments with varying clay and solid fractions showed that the abundance and viscosity of the interstitial fluid affect debris‐flow dynamics, erosional mechanisms and erosion magnitude. High viscosity of the interstitial fluid inhibits the mobility of the debris flow, the movement of the individual grains and the transfer of momentum to the bed by impacts, and therefore inhibits erosion. High solid content possibly decreases the pore pressures in the debris flow and the transport capacity, inhibiting erosion, despite high shear stresses and impact forces. Our results show that bed erosion quantities and mechanisms may vary between debris flows with contrasting composition, and stress that entrainment models and volume‐growth predictions may be substantially improved by including compositional effects.

Volumetric additive manufacturing of silica glass with microscale computed axial lithography.

Glass is increasingly desired as a material for manufacturing complex microscopic geometries, from the micro-optics in compact consumer products to microfluidic systems for chemical synthesis and biological analyses. As the size, geometric, surface roughness, and mechanical strength requirements of glass evolve, conventional processing methods are challenged. We introduce microscale computed axial lithography (micro-CAL) of fused silica components, by tomographically illuminating a photopolymer-silica nanocomposite that is then sintered. We fabricated three-dimensional microfluidics with internal diameters of 150 micrometers, free-form micro-optical elements with a surface roughness of 6 nanometers, and complex high-strength trusses and lattice structures with minimum feature sizes of 50 micrometers. As a high-speed, layer-free digital light manufacturing process, micro-CAL can process nanocomposites with high solids content and high geometric freedom, enabling new device structures and applications.