Compact Aggregates Research Articles

Effect of the critical melting treatment on the short/long-term retrogradation behaviour of maize starch

The shortand long-term retrogradation properties in normal maize starch (N-S) by critical melting treatment (CMT; including TO (onset temperature) melting (OM), TP (peak temperature) melting (PM), and TC (conclusion temperature) melting (CM)) were studied. Results indicated that CMT promoted short-term (1 day) and long-term (7 days) retrogradation of N-S in the following order: PM > CM > OM. After storage for 7 days, following the PM treatment, the gel hardness, the retrogradation degree, and relative crystallinity increased to 4.67 N, 13.191%, 8.58% from 2.87 N, 9.972%, and 6.20%, respectively. PM treatment resulted in harder starch granules, promoting the rearrangement of the starch crystalline structure during cold storage. This was confirmed by the increased storage modulus, decreased iodine blue value, reduced gap in the gel network, and compact aggregate formation. Results indicated that CMT can promote the retrogradation properties of N-S.

Relaxation-weighted MRI analysis of biofilm EPS: Differentiating biopolymers, cells, and water

Biofilms are a highly complex community of microorganisms embedded in a protective extracellular polymeric substance (EPS). Successful biofilm control requires a variety of approaches to better understand the structure-function relationship of the EPS matrix. Magnetic resonance imaging (MRI) is a versatile tool which can measure spatial structure, diffusion, and flow velocities in three dimensions and in situ. It is well-suited to characterize biofilms under natural conditions and at different length scales. MRI contrast is dictated by T1 and T2 relaxation times which vary spatially depending on the local chemical and physical environment of the sample. Previous studies have demonstrated that MRI can provide important insights into the internal structure of biofilms, but the contribution of major biofilm components—such as proteins, polysaccharides, and cells—to MRI contrast is not fully understood. This study explores how these components affect contrast in T1-and T2-weighted MRI by analyzing artificial biofilms with well-defined properties modeled after aerobic granular sludge (AGS), compact spherical biofilm aggregates used in wastewater treatment. MRI of these biofilm models showed that certain gel-forming polysaccharides are a major source of T2 contrast, while other polysaccharides show minimal contrast. Proteins were found to reduce T2 contrast slightly when combined with polysaccharides, while cells had a negligible impact on T2 but showed T1 contrast. Patterns observed in the model biofilms served as a reference for examining T2 and T1-weighted contrast in the void spaces of two distinct AGS granules, allowing for a qualitative evaluation of the EPS components which may be present. Further insights provided by MRI may help improve understanding of the biofilm matrix and guide how to better manage biofilms in wastewater, clinical, and industrial settings.

The Bulk Densities of Small Solar System Bodies as a Probe of Planetesimal Formation

Constraining the formation processes of small solar system bodies is crucial for gaining insights into planetesimal formation. Their bulk densities, determined by their compressive strengths, offer valuable information about their formation history. In this paper, we utilize a formulation of the compressive strength of dust aggregates obtained from dust N-body simulations to establish the relation between the bulk density and diameter. We find that this relation can be effectively approximated by a polytrope with an index of 0.5, coupled with a formulation of the compressive strength of dust aggregates. The lowest-density trans-Neptunian objects (TNOs) and main-belt asteroids (MBAs) are well reproduced by dust aggregates composed of 0.1 μm sized grains. However, most TNOs, MBAs, comets, and near-Earth asteroids (NEAs) exhibit higher densities, suggesting the influence of compaction mechanisms such as collision, dust grain disruption, sintering, or melting, leading to further growth. We speculate that there are two potential formation paths for small solar system bodies. One involves the direct coagulation of primordial dust grains, resulting in the formation of first-generation planetesimals, including the lowest-density TNOs, MBAs, and the parent bodies of comets and NEAs. In this case, comets and NEAs are fragments or rubble piles of first-generation planetesimals, and the objects themselves or the rubble are composed of 0.1 μm sized grains. The other path involves the further potential fragmentation of first-generation planetesimals into the compact dust aggregates observed in protoplanetary disks, resulting in the formation of second-generation planetesimals composed of compact dust aggregates, which may contribute to explaining another formation process of comets and NEAs.

Long-term Chinese milk vetch incorporation promotes soil aggregate stability by affecting mineralogy and organic carbon

Soil aggregates profoundly impact soil sustainability and crop productivity, and they are influenced by complex interactions between minerals and organics. This study aimed to elucidate the alterations in mineralogy and soil organic carbon (SOC) following long-term green manure incorporation and the effect on soil aggregates. Based on 5- and 36-year field experiments, surface soil samples (0-20 cm) were collected from Alfisol and Ferrisol soils subjected to rice-rice-winter fallow (CK) and rice-rice-Chinese milk vetch (MV) treatments to investigate aggregate stability, mineralogy, SOC composition, and soil microstructural characteristics. The results showed that high clay-content Ferrisol exhibited greater aggregate stability than low clay-content Alfisol. The phyllosilicates in Alfisol primarily comprised illite and vermiculite, whereas those in Ferrisol with high-content free-form Fe oxides (Fed) were dominated by kaolinite. Additionally, the clay fraction in Ferrisol contained more aromatic-C than the clay fraction in Alfisol. The 36-year MV incorporation significantly increased the Ferrisol macroaggregate stability (9.57-13.37%), and it also facilitated the transformation of vermiculite into kaolinite and significantly increased the clay, Fed, and aromatic-C contents in Ferrisol. Backscattered electron (BSE)-scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) revealed a compact aggregate structure in Ferrisol with co-localization of Fe oxides and kaolinite. Moreover, the partial least path model (PLS-PM) revealed that clay content directly improved macroaggregate stability, and that kaolinite and Fed positively and directly affected clay or indirectly modulated clay formation by increasing the aromatic-C levels. Overall, long-term MV incorporation promotes clay aggregation by affecting mineral transformation to produce more kaolinite and Fe oxides and retain aromatic-C, and it ultimately improves aggregate stability..

Comparative analysis of carrageenan/ovalbumin and carrageenan oligosaccharide/ovalbumin complexes

The saccharides ι-carrageenan (ι-CG) and ι-carrageenan oligosaccharides (ι-CO) exhibit different molecular chain lengths and charge intensities, which are pivotal determinants of their interactions with ovalbumin (OVA). This study investigated the interaction mechanisms between OVA and ι-CG as well as between OVA and ι-CO using experimental methods and molecular docking. The results of zeta potential showed that the strongest electrostatic interaction occurred at an OVA/ι-CG ratio of 100:13 (−1.59 ± 0.41 mV) and an OVA/ι-CO ratio of 100:10 (−1.32 ± 0.30 mV). The OVA/ι-CG complexes showed higher turbidity (1.63 ± 0.08 cm−1). Furthermore, Fourier transform infrared spectroscopy showed that ι-CG significantly altered the secondary structure of OVA, whereas ι-CO did not affect it. Fluorescence spectroscopy also verified the interactions in the OVA/ι-CG and OVA/ι-CO complexes. Both complexes exhibited shear-thinning behaviour; the largest storage modulus (G′) and loss modulus (G″) were observed at 100:13 and 100:10 ratios for OVA/ι-CG OVA/ι-CO samples, respectively. ι-CG induced OVA to form more loosely clumped aggregates, whereas OVA and ι-CO formed compact granular aggregates when observed using confocal scanning laser microscopy. Molecular docking results showed that more salt bridges were formed between ι-CG and OVA than between ι-CO and OVA. A schematic model was established to elucidate the effects of ι-CG and ι-CO on OVA. This study provides instructions for designing innovative food systems based on different charge intensities and chain lengths of saccharides.

Hydrogel foam with designed structural properties of egg white protein through building aggregates as potential dysphagia food

To address the growing demand for texture-modified foods (TMFs) among individuals with dysphagia, the structural properties of alkali-heat treated egg white protein aggregates (AHEWP) were investigated to developed hydrogel foams as suitable soft gels. The results showed that AHEWP presented partially unfolded and higher content of β-sheet structures. The alkaline shift suppressed thermally denatured molecular unfolding (exposing aromatic and hydrophobic amino acids) and blocked hydrogen bonding, leading to the generation of small-sized AHEWP. Within the pH range of 10.5–11.25, raising temperature promoted more covalent bonding to produce structurally compact aggregates. Compared to EWP, AHEWP exhibited remarkably stable foams (85.62–91.99% of FS) and could form Ca2+ crosslinked cold gels, which were contributed to the formation of hydrogel foam. The alkali-heat treatment of high intensity gave a less increase in surface tension and richer interfacial proteins. SEM and microrheology revealed that the alkaline shift transformed the hydrogel network of AHEWP into a “sheet-like” stacking structure, accompanied by a rise in the macroscopic viscosity index and a change of gelation rate. At pH 11.0 and 11.25, the higher temperature, the denser the pore and the lower the elasticity index. The self-supporting property and water loss of AHEWP hydrogel foam reduced, and their time stability enhanced with increasing pH and/or temperature. According to IDDSI, AHEWP hydrogel and hydrogel foam were attributed to level 4–7 and 4–5, respectively. Overall, AHEWP has the potential to establish hydrogel foam systems that will serve as a valuable reference for designing protein-based soft gel TMFs for dysphagia diets.

Charge Detection Mass Spectrometry Reveals Conformational Heterogeneity in Megadalton-Sized Monoclonal Antibody Aggregates.

Aggregation of protein-based therapeutics can occur during development, production, or storage and can lead to loss of efficacy and potential toxicity. Native mass spectrometry of a covalently linked pentameric monoclonal antibody complex with a mass of ∼800 kDa reveals several distinct conformations, smaller complexes, and abundant higher-order aggregates of the pentameric species. Charge detection mass spectrometry (CDMS) reveals individual oligomers up to the pentamer mAb trimer (15 individual mAb molecules; ∼2.4 MDa) whereas intermediate aggregates composed of 6-9 mAb molecules and aggregates larger than the pentameric dimer (1.6 MDa) were not detected/resolved by standard mass spectrometry, size exclusion chromatography (SEC), capillary electrophoresis (CE-SDS), or by mass photometry. Conventional quadrupole time-of-flight mass spectrometry (QTOF MS), mass photometry, SEC, and CE-SDS did not resolve partially or more fully unfolded conformations of each oligomer that were readily identified using CDMS by their significantly higher extents of charging. Trends in the charge-state distributions of individual oligomers provides detailed insight into how the structures of compact and elongated mAb aggregates change as a function of aggregate size. These results demonstrate the advantages of CDMS for obtaining accurate masses and information about the conformations of large antibody aggregates despite extensive overlapping m/z values. These results open up the ability to investigate structural changes that occur in small, soluble oligomers during the earliest stages of aggregation for antibodies or other proteins.

Different rheological behaviors of reinforced poly(methylvinylsiloxane) by mesoporous and spherical silica microparticles

To elucidate the mechanism underlying the high performance of mesoporous silica aerogel microparticle (SAG) in reinforcing polymers, the hydrodynamic effect and reinforcement effect of SAG microparticle in Poly-methylvinylsiloxane (PMVS) were investigated. For comparison, regular spherical silica particles (SS) with a comparable particle size and smooth surface were also incorporated into the study as a contrasting filler. It was found that SAG tended to form aggregates with high aspect ratio (shape factor f values between 16-20) and highly branched backbone structures (x = 1.95). However, these aggregates are more loosely packed (df = 1.7) and easily break into smaller flocs under the influence of shear forces. The load-bearing mechanism of the spatial network formed by these aggregates as nodes was akin to physical gels controlled by bond-bending forces (BBFs), with a scaling exponent of G*r with φe-φc of ν = 3.84, close to the theoretical value of the BBFs model. In contrast, the SS particles formed more compact aggregates (f value approximately 1.6) in PMVS, with load-bearing characteristics of the spatial network formed by them closer to chemical gels controlled by central forces (CFs). The scaling exponent of G*r with φe-φc for SS/PMVS was found to be ν = 2.15, close to the theoretical value of the CFs model.

Tumor-stroma contact ratio - a novel predictive factor for tumor response to chemoradiotherapy in locally advanced oropharyngeal cancer

The growth pattern of oropharyngeal squamous cell carcinomas (OPSCC) varies from compact tumor cell aggregates to diffusely infiltrating tumor cell-clusters. The influence of the growth pattern on local tumor control and survival has been studied mainly for surgically treated oral cavity carcinomas on a visual basis. In this study, we used multiplex immunofluorescence staining (mIF) to examine the antigens pan-cytokeratin, p16INK4a, Ki67, CD271, PD-L1, and CD8 in pretherapeutic biopsies from 86 OPSCC. We introduce Tumor-stroma contact ratio (TSC), a novel parameter, to quantify the relationship between tumor cells in contact with the stromal surface and the total number of epithelial tumor cells. mIF tumor cores were analyzed at the single-cell level, and tumor-stromal contact area was quantified using the R package "Spatstat". TSC was correlated with the visually assessed invasion pattern by two independent investigators. Furthermore, TSC was analyzed in relation to clinical parameters and patient survival data to evaluate its potential prognostic significance.Higher TSC correlated with poor response to (chemo-)radiotherapy (r = 0.3, p < 0.01), and shorter overall (OS) and progression-free (PFS) survival (median OS: 13 vs 136 months, p < 0.0001; median PFS: 5 vs 85 months, p < 0.0001). Visual categorization of growth pattern according to established criteria of tumor aggressiveness showed interobserver variability increasing with more nuanced categories (2 categories: k = 0.7, 95 %-CI: 0.55 - 0.85; 4 categories k = 0.48, 95 %-CI: 0.35 - 0.61).In conclusion, TSC is an objective and reproducible computer-based parameter to quantify tumor-stroma contact area. We demonstrate its relevance for the response of oropharyngeal carcinomas to primary (chemo-)radiotherapy.

The Characterization of Multifaceted PREP1 Peptides Provides Insights into Correlations between Spectroscopic and Structural Properties of Amyloid-like Assemblies.

The widespread ability of proteins and peptides to self-assemble by forming cross-β structure is one of the most significant discoveries in structural biology. Intriguingly, the cross-β association of proteins/peptides may generate intricate supramolecular architectures with uncommon spectroscopic properties. We have recently characterized self-assembled peptides extracted from the PREP1 protein that are endowed with interesting structural/spectroscopic properties. We here demonstrate that the green fluorescence emission of the peptide PREP1[117-132] (λem ~520 nm), can be induced by excitation with UV radiation. The associated unusually large Stokes shift (Δλ ~150 nm) represents, to the best of our knowledge, the first evidence of an internal resonance energy transfer in amyloid-like structures, where the blue emission of some assemblies becomes the excitation radiation for others. Moreover, the characterization of PREP1[117-132] variants provides insights into the sequence/structure and structure/spectroscopic properties relationships. Our data suggests that the green fluorescence is plausibly associated with antiparallel β-sheet states of the peptide whereas parallel β-sheet assemblies are only endowed with blue fluorescence. Notably, the different PREP1[117-132] variants also form assemblies characterized by distinct morphologies. Indeed, the parent peptide and single mutants form compact but structured aggregates whereas most of the double mutants exhibit elongated and highly extended fibers.

Abstract 6778: New microplate platform with cryopreserved 3D tumor spheroids for faster and convenient pre-clinical testing

Abstract Drug discovery and safety testing depend on predictive in vitro models, including multicellular tissues with organotypic functions. While traditional 2D tumor cell cultures have been extensively used in early drug screening due to their user-friendly nature, automation compatibility, and high throughput, they fall short in representing the intricate 3-dimensional structure, physiology, and complex multicellular nature of actual tumors. However, generating such 3D tissues for each test campaign is labor intensive. In addition, not all researchers have the resources to establish these 3D models. To pave the way, we developed a new platform that offers a range of cryopreserved 3D tumor models in micro plate format allowing for high-content screening. It enables users to start testing compounds within a 3-to-5 days simply by thawing an ARCTis™ plate (Always Ready Cryo Tissues) and following clear instructions. Another advantage of these cryopreserved 3D models derives from the fact that they are made in larger batches which means the start point for compound testing is always the same. This improves data quality, maximizes the test window length, and makes the data comparable across work groups. Currently, our growing portfolio consists of 25 tumor cell lines from ATCC representing the most common solid tumors. Their functionality has been determined based on efficacy tests for each cell line with the apoptotic agent Staurosporine. Various cell lines exhibited compact spheroids with a round morphology, less compact aggregates with non-spherical morphology, or loose cell-cell interaction aggregates, which can correlate with their tumor site of origin. Upon treatment with Staurosporine the dose-response profiles indicated growth inhibition, tumor shrinkage, or tumor cell killing effects based on size assessment and cell metabolic analysis (ATP). Moreover, we demonstrated the robust performance of these assays from plates stored for up to 6 months at -80°C.In conclusion, this groundbreaking approach addresses the limitations of traditional 2D cell cultures by providing a high-throughput, in-plate frozen, 3D cell culture platform. By offering a combination of a more physiologically relevant representation of tumors with a robust frozen-storage and time flexible assay platform our method holds great promise for advancing cancer drug discovery by easing the exploration of complex drug testing screens in vitro. Citation Format: Nils Goedecke, Simon Stroebel, Simon Hutter, Tala Issa, Irina Agarkova, Laure-Anne Ligeon, Olivier Frey. New microplate platform with cryopreserved 3D tumor spheroids for faster and convenient pre-clinical testing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6778.

Kristjánite, KNa2H(SO4)2, a new fumarolic mineral from Iceland containing the [SO4–H–SO4]3– anion in the crystal structure

Abstract Kristjánite, KNa2H(SO4)2, is a new mineral (IMA2022–131) found in a high-temperature fumarole on Fimmvörðuháls, Iceland. It is monoclinic, P21/n, a = 6.9625(1), b = 9.9953(1), c = 11.0928(2) (Å), β = 105.637(2)° and V = 743.40(2) Å3. Kristjánite forms colourless transparent crystals up to ~100 μm in size in compact aggregates with metathénardite, belomarinaite, aphthitalite, ivsite and an unknown mineral with tentative composition K2NaH(SO4)2, or grows in white globules of smaller grains on their surface. The eight strongest maxima in a powder X-ray diffraction diagram are [d, Å (Intensity)] 4.37 (59), 3.65 (32), 3.48 (78), 3.36 (100), 3.18 (76), 2.83 (43), 2.73 (38) and 2.405 (23). The mineral represents a novel crystal structure type. In it, K is coordinated by eight O atoms, and two symmetrically independent Na atoms by seven O atoms. Two symmetrically independent S atoms are in tetrahedral coordination by O atoms. A close to linear, very short hydrogen bond (2.44 Å), connects the two to a SO4–H–SO4 dimer. K and Na coordination polyhedra share vertices, edges and even faces forming with sulfate tetrahedra a tight structure with narrow [100] channels lined on two opposite sides by hydrogen bonds.

Immune mapping of human tuberculosis and sarcoidosis lung granulomas.

Tuberculosis (TB) and sarcoidosis are both granulomatous diseases. Here, we compared the immunological microenvironments of granulomas from TB and sarcoidosis patients using in situ sequencing (ISS) transcriptomic analysis and multiplexed immunolabeling of tissue sections. TB lesions consisted of large necrotic and cellular granulomas, whereas "multifocal" granulomas with macrophages or epitheloid cell core and a T-cell rim were observed in sarcoidosis samples. The necrotic core in TB lesions was surrounded by macrophages and encircled by a dense T-cell layer. Within the T-cell layer, compact B-cell aggregates were observed in most TB samples. These B-cell clusters were vascularized and could contain defined B-/T-cell and macrophage-rich areas. The ISS of 40-60 immune transcripts revealed the enriched expression of transcripts involved in homing or migration to lymph nodes, which formed networks at single-cell distances in lymphoid areas of the TB lesions. Instead, myeloid-annotated regions were enriched in CD68, CD14, ITGAM, ITGAX, and CD4 mRNA. CXCL8 and IL1B mRNA were observed in granulocytic areas in which M. tuberculosis was also detected. In line with ISS data indicating tertiary lymphoid structures, immune labeling of TB sections expressed markers of high endothelial venules, follicular dendritic cells, follicular helper T cells, and lymph-node homing receptors on T cells. Neither ISS nor immunolabeling showed evidence of tertiary lymphoid aggregates in sarcoidosis samples. Together, our finding suggests that despite their heterogeneity, the formation of tertiary immune structures is a common feature in granulomas from TB patients.

Aggregation and breakage dynamics of alumina particles under shear by coupled Computational Fluid Dynamics – Discrete Element Method

HypothesisShear affects simultaneous aggregation and fragmentation of fine particles. Understanding the effect of shear on the dynamics of particle aggregation and break-up is important to predict aggregate size and structure. It is hypothesized that there is a transition from pure breakage of large aggregates to regimes where restructuring and aggregation also play a role as aggregates become smaller. SimulationsHere, aggregation and fragmentation dynamics of alumina particles are investigated under laminar shear flow using Discrete Element Method (DEM) coupled with Computational Fluid Dynamics (CFD). The effect of the shear rate on the aggregation and breakage rates is quantified accounting for particle–particle and particle–fluid interactions. FindingsHigh shear rates promote the formation of small, compact aggregates. The collision efficiency decreases with increasing shear rate following a power law for shear rates higher than 1250 s−1. The transition from the pure breakage limit to the region dominated by breakage and restructuring has been observed for the first time. The breakage rate decreases significantly as the transition occurs upon decreasing aggregate size. CFD-DEM-derived collision efficiency and breakage rate equations are proposed that can be readily employed in detailed population balance equation models for industrial particle process design.

B ← N coordination bond reinforced dynamic fluorescence of pH-responsive amphiphile alginate aggregates for anti-counterfeiting

High quantum yield polysaccharide-based materials are significative for the dynamic anti-counterfeiting, while that are limited by weak fluorescence. However, natural polysaccharides with weak fluorescence are not suitable for anti-counterfeiting. Herein, alginate derivatives (SA-PBA) exhibiting aggregation-induced emission with high-quantum yields were synthesized by grafting phenylboronic acid (PBA) onto a sodium alginate (SA) chain. As the concentration increases, polymer assembly can be induced to form more compact soft colloidal aggregates, which enhances the fluorescence properties of alginate derivatives by introducing B ← N coordination bonds in the hydrophobic microregions. Interestingly, the clustered aggregates of SA-PBA can be dynamically controlled by pH, realizing the reversible adjustment of fluorescence. The corresponding mechanism is revealed by the combination of coarse-grained simulations and experiments. It is found that SA-PBA uses a hydrophobic driving force and hydrogen bond interaction to self-assemble in an aqueous solution and promote fluorescence emission. Moreover, the fluorescence quantum yield of SA-PBA can reach 14.4 % and can be reversibly altered by tuning soft colloidal microstructures. Therefore, a reversible information encryption system of SA-PBA is developed for anti-counterfeiting. This work shed some light on how to design novel anti-counterfeit materials based on natural polysaccharides and optimize the dynamic fluorescence conditions.

Fungal pellets of Pleurotus ostreatus and Rhizopus stolonifer for biotechnological applications: Characterization and production optimization using Taguchi methodology

Filamentous fungi are known for their significant potential in biotechnology, thanks to their versatile enzyme systems with various applications. However, dealing with their growth patterns and structural configurations presents significant challenges. To tackle these issues, fungal pellets are emerging as potential solutions, providing compact biomass aggregates that offer distinct advantages for bioprocesses. This study delves into characterization and optimizing pellet formation for Pleurotus ostreatus and Rhizopus stolonifer using the Taguchi methodology, aiming to enhance their biotechnological applications. By systematically varying parameters such as agitation level (AL), glucose concentration (GC), and inoculum size (IS), we identified key factors influencing pellet formation. Results indicate that P. ostreatus forms pellets in rich media from mycelium, while R. stolonifer requires a minimal medium with pH modifications for pelletization via a coagulative mechanism. The optimization process reveals that agitation level is a crucial factor for maximizing pellet production in both models, while the other factors do not seem to influence the process significantly but impact the morphology and quantity of pellets. The results suggest that by optimizing parameters using the Taguchi method, it is possible to achieve acceptable pellet formation performance in both fungi. Understanding these factors is essential for improving the efficiency of biotechnological processes involving fungal biomass, providing valuable insights into enhancing fungal pellet production for various applications.

Light-induced quinone conformation of polymer donors toward 19.9% efficiency organic solar cells

UV-light illumination converts the aromatic conformation of polymer donors into a rigid quinone structure, resulting in compact fibrillar aggregation of the active layer to achieve a maximum efficiency of 19.9% of single-junction organic solar cells.

Cryptanalysis of Compact Certificateless Aggregate Signature Schemes for HWMSNs and VANETs

Cryptanalysis of Compact Certificateless Aggregate Signature Schemes for HWMSNs and VANETs

Rapid and clean dewatering of dredged sediment via coupling of a two-step flocculation and geotextile filtration

The use of flocculation processes coupled with geotextile technology for dredged sediment dewatering is promising in recent years. However, two main issues are encountered: firstly, the occurrence of clogging resulting in reduced dewatering rate, and secondly, contamination of the residual water, necessitating additional treatment, consequently leading to an increase in operational costs. Therefore, this study proposed an innovative approach employing a two-step flocculation combined with geotextile filtration method to achieve rapid and clean dewatering of dredged sediment. The jar test implementation of a two-step flocculation process at the optimal flocculation dosages resulted in a dewatering rate that was about 16.7 times compared to commercial flocculant (APAM) conditioning. The increased dewatering rate is mainly attributed to the formation of large and compact flocs aggregates (d50 > 160 μm) formed through the two-step flocculation. These aggregates facilitate the formation of a filter cake with a high porosity of 45 %, a low tortuosity of 1.53, a uniform pore-throat structure, and excellent connectivity of pore space. Compared with APAM, the value of turbidity, COD, NH4+-N, and phosphorus in the residual water can be decreased from 36.4 to 3.8 NTU, 28.6 to 8.3 mg/L, 2.3 to 1.6 mg/L, 0.15 to 0.04 mg/L, respectively, which meet the environmental quality standards for surface water (type V) in China. In addition, the technology is proven to be economical as the cost of flocculants is less than half the cost of other reported flocculants. Overall, this work presents a new and cost-effective approach for achieving both rapid and clean dewatering of dredged sediments, which is very promising for practical applications.

Controlling the coarsening dynamics of ferrogranular networks by means of a vertical magnetic field.

We are exploring in experiments the aggregation process in a shaken granular mixture of glass and magnetized steel beads, filled in a horizontal vessel, after the shaking amplitude is suddenly decreased. Then the magnetized beads form a transient network that coarsens in time into compact clusters, resembling a viscoelastic phase separation [Tanaka, J. Phys.: Condens. Matter 12, R207 (2000)0953-898410.1088/0953-8984/12/15/201], where attached beads represent the slow phase. Here we investigate how a homogeneous magnetic field oriented in vertical direction impedes the emergence and growth of the networks. With increasing field amplitude this phase is replaced by a fluctuating arrangement of repelling, isolated steel beads. The experimental results are compared with those of computer simulations. Coarse-grained molecular dynamics confirms the impact of an applied magnetic field on the structural transitions and allows us to investigate long-time regimes and magnetic response not yet accessible in the experiment. It turns out that an applied magnetic field has different impacts, depending on it strength. It can be used either to slow down the dynamics of the structural transitions without changing the type of the resulting phases and only affecting the amount and sizes of clusters, or to fully impede the formation of network-like and compact aggregates of steel beads.