Aggregate Structure Research Articles

Enhancing the thermal properties of foam concrete with pumice-encapsulated soy wax phase change material: a novel approach.

This study explored an innovative technique for improving the thermal characteristics of foam concrete by incorporating soy wax phase change material (PCM) encapsulated within pumice. The core of this research is the development of PCM-pumice aggregates through the macro encapsulation of soy wax. This process involves direct impregnation, where melted soy wax is uniformly distributed within the porous structure of lightweight pumice aggregates. The thermal properties of the resulting foam concrete, notably its thermal conductivity, were rigorously evaluated. This evaluation entailed measuring the conductivity using a heat flow meter and subjecting the concrete samples to controlled temperature cycles, with a focus on the 25°C and 55°C marks. These specific temperatures were chosen to assess the impact of the PCM phase change on the thermal behavior of the concrete. Key findings indicate that the incorporation of PCM-pumice aggregates markedly improves thermal conductivity and heat retention in the solid state while simultaneously reducing fluidity, density, and compressive strength as a result of increased cohesion and porosity. Thermal conductivity significantly increased by up to 37% in the solid state relative to the control mix, due to the phase change material occupying air gaps within the concrete. Conversely, the thermal conductivity decreased in the liquid state, utilizing the PCM's latent heat capacity to lower heat transfer rates.

In vitro digestion of glycoproteins from Porphyra haitanensis: Effects on structure, hypoglycemic activity, and fermentation characteristics.

This study was to investigate the fundamental composition and structure, hypoglycemic activity and fermentation characteristics of Porphyra haitanensis glycoprotein (PG) following in vitro simulate gastrointestinal digestion. After in vitro digestion, PG was degraded into peptides, amino acids, and reducing sugars, and the digested PG structure evolved into functional aggregates that were more favorable for regulating intestinal flora. Such aggregated structure might inhibit the accessibility of digestive enzymes and significantly enhanced its hypoglycemic activity. Compared with undigested PG, the inhibition rate of digested PG on α-amylase and α-glucosidase was increased by 4.70% and 7.69%, respectively (P<0.05). Furthermore, digested PG enhanced the abundances of Lactobacillus and Bifidobacterium, etc., which was positive related with the increased secretion of butyric acid, thereby playing a role in regulating intestinal homeostasis and blood glucose homeostasis in the host. Our findings can offer novel perspectives on the regulation of the intestinal flora by glycoproteins during gastrointestinal digestion.

Development and characterization of soy protein-based custard-like soft foods for elderly individuals with swallowing difficulties.

There is growing interest in developing protein-rich foods for the elderly using plant proteins. The application of soy protein isolate (SPI) as a model protein to create protein-rich, custard-like soft foods presents a unique opportunity for innovative formulations tailored to those within the aging population suffering from swallowing difficulties. This study investigated the physicochemical and textural properties of custard-type soft food formulations developed using SPI for dysphagic elderly individuals, with the goal of achieving characteristics similar to those of optimal milk protein-based counterparts. The protein content in the SPI-based custards varied from 8.9% to 13.9% and the milk-protein based custards had 8.9% protein content. There was a substantial difference in textural, rheological and creep resistance and other properties between SPI and milk protein-based formulations. The SPI-based custards also had lower water-holding capacity, looser structure, and higher level of insoluble protein aggregates. The SPI-based custards imparted a more spreadable mouthfeel suitable for the aging population. The custards containing 13.9% SPI had higher gel strength, viscosity, texture, and product stability. All of these custards were classified as Level 6 - Soft & Bite-sized dysphagia diet, based on International Dysphagia Diet Standardisation Initiative (IDDSI) tests. Instrumental IDDSI tests for Level 6 foods corroborated these observations, yielding reliable and consistent data. This research provides insights for developing protein-rich plant-based soft foods intended for the elderly population that have characteristics close to milk protein-based custards and comply with IDSSI criteria.

Radiation-Induced Damage to Concrete Biological Shielding Materials: A State-of-The-Art Review

Concrete is the primary material for such shielding due to its mechanical and structural properties, suitable for neutron and gamma radiation protection. This review provides a comprehensive examination of the impact of nuclear irradiation on the structural integrity of concrete used in biological shielding within nuclear power plants (NPPs). This review highlights the critical role of the hydrogen content of concrete in attenuating neutron flux and its versatility in shape, density, and cost-effectiveness. The review was systematically collected and reviewed previous research papers on the topic, focusing on studies that address the degradation of mechanical properties in concrete exposed to gamma and neutron radiation. Our methodology involved an extensive literature search, critical analysis, and synthesis of findings from peer-reviewed journals, conference proceedings, and technical reports that specifically address the degradation of mechanical properties in concrete structures exposed to gamma and neutron radiation. Gamma radiation induces radiolysis in hydrated cement paste, while neutron radiation causes alterations in the crystalline structure of aggregates, leading to volumetric expansion and reduced mechanical strength. Additionally, this review highlights the combined effects of chemical attacks, moisture, and elevated temperatures on concrete degradation during reactor operation. The key findings underscore the need for further research into the degradation mechanisms of concrete biological shielding, emphasizing the influence of various types of nuclear radiation. This understanding is crucial for ensuring concrete’s long-term durability and effectiveness in NPPs, thereby contributing to the safe and sustainable operation of nuclear energy facilities.

Biofilm characterisation of Mycoplasma bovis co-cultured with Trueperella pyogenes

Mycoplasma pneumonia, caused by Mycoplasma bovis (Mycoplasmopsis bovis; M. bovis), is linked with severe inflammatory reactions in the lungs and can be challenging to treat with antibiotics. Biofilms play a significant role in bacterial persistence and contribute to the development of chronic lesions. A recent study has shown that polymicrobial interactions between species are an important factor in biofilm formation, yet the precise mechanism of biofilm formation in M. bovis remains unknown. By assuming multiple pathogen infections in the bovine respiratory disease complex (BRDC), this study examined the characterisation of the polymicrobial relationship between M. bovis and Trueperella pyogenes (T. pyogenes) during biofilm formation. Autopsies were performed on four Holstein calves (two chronic Mycoplasma pneumonia calves and two control calves). Bacterium-like aggregation structures (> 10 μm), which were assumed to be biofilms of M. bovis in vivo, were observed adhering to the cilia in calves with Mycoplasma pneumonia. M. bovis released an extracellular matrix to connect with neighbouring bacteria and form a mature biofilm on the plate. Biofilm formation in the co-culture of M. bovis and T. pyogenes (strain T1: 1 × 105 and 1 × 106 CFU/well) significantly increased (p < 0.05 and p < 0.01; 64.1% and 64.8% increase) compared to that in a single culture of these bacteria. Furthermore, some large aggregates (> 40 μm), composed of M. bovis and T. pyogenes, were observed. The morphological characteristics of this biofilm were similar to those observed in vivo compared to a single culture. In conclusion, the polymicrobial interaction between M. bovis and T. pyogenes induces biofilm formation, which is associated with increased resistance to antimicrobial agents, and this exacerbates the progression of chronic Mycoplasma pneumonia.

Methyl side-groups control the Ia3̄d phase in core-non-symmetric aryloyl-hydrazine-based molecules.

Control of the formation of liquid crystalline Ia3̄d gyroid phases and their nanostructures is critical to advance materials chemistry based on the structural feature of three-dimensional helical networks. Here, we present that introducing methyl side-group(s) and slight non-symmetry into aryloyl-hydrazine-based molecules is unexpectedly crucial for their formation and can be a new design strategy through tuning intermolecular interactions: the two chemical modifications in the core portion of the chain-core-chain type molecules effectively lower and extend the Ia3̄d phase temperature ranges with the increased twist angle between neighboring molecules along the network. The detailed analyses of the aggregation structure revealed the change in the core assembly mode from the double-layered core mode of the mother molecule (without methyl groups) to the single-layered core mode. Such changes are explained in terms of modified intermolecular interactions in those phases employing quantum chemical calculations.

PFSA‐Ionomer Dispersions to Thin‐Films: Interplay Between Sidechain Chemistry and Dispersion Solvent

AbstractIn fuel‐cell catalyst layers (CLs), ionomers exists as nanoscale thin‐films binding catalyst particles, wherein ionic and gaseous species transport to catalyst sites. To improve film function, ionomers have been designed based on the prototypical perfluorosulfonic acid (PFSA). Since CLs are fabricated through solution‐based processing of inks, understanding how ink/dispersion solvent impacts ionomer interactions and function is important to guide future ionomer design. Herein, PFSA and its chemical derivatives are characterized from dispersion (in solvent) to thin film (cast on support) to investigate the impact of solvent water content on ionomer dispersion (structure, acidity) and resulting film properties. Dispersion characterization reveals that secondary aggregate structure depends on the sidechain chemistry, but all PFSA‐based ionomers evolve similarly as dispersion becomes water‐rich. The differences in aggregation alter ionomer adsorption and thin film morphology. Hydrophilic domain spacing and orientation are affected primarily by sidechain chemistry, and modulated by solvent composition. Thin‐film conductivity correlates with hydration and nanodomain alignment, signifying the role of morphology in properties. Overall, this work provides insights into how chemistry can be used to coarse‐tune structure–property relationships, while processing solvent is for fine‐tuning of dispersion‐film interplay for controlling CL‐ionomer function, which can be translated to other chemistries and ink formulations.

Composition and liquid-to-solid maturation of protein aggregates contribute to bacterial dormancy development and recovery

Recalcitrant bacterial infections can be caused by various types of dormant bacteria, including persisters and viable but nonculturable (VBNC) cells. Despite their clinical importance, we know fairly little about bacterial dormancy development and recovery. Previously, we established a correlation between protein aggregation and dormancy in Escherichia coli. Here, we present further support for a direct relationship between both. Our experiments demonstrate that aggregates progressively sequester proteins involved in energy production, thereby likely causing ATP depletion and dormancy. Furthermore, we demonstrate that structural features of protein aggregates determine the cell’s ability to exit dormancy and resume growth. Proteins were shown to first assemble in liquid-like condensates that solidify over time. This liquid-to-solid phase transition impedes aggregate dissolution, thereby preventing growth resumption. Our data support a model in which aggregate structure, rather than cellular activity, marks the transition from the persister to the VBNC state.

Building a Highly Stable Red/Near Infrared Afterglow Library with Highly Branched Structures

AbstractAchieving organic red/near infrared (NIR) phosphorescence at high temperatures is theoretically challenging because of the severe nonradiative transitions of excited triplet states with low energy gaps. This study realizes bright and persistent red/NIR afterglow with excellent high‐temperature resistance up to 413 K via highly efficient (≈100%) phosphorescence resonance energy transfer (PRET) from rationally designed branched phosphorescence luminogens as energy donors to red/NIR dyes as acceptors, coupled with optimized aggregated structures. According to systematic investigations, the abundant internal cavities formed by the highly branched luminogens in solid states ensure dye loading and space limitation, which can considerably suppress nonradiative transitions at high temperatures, promoting a persistent red/NIR afterglow with excellent stability. Moreover, 16 types of host–guest systems with varied topological structures of branched luminogens and different red/NIR dyes of various sizes confirm the universality of the strategy. This study provides an efficient approach to achieve a highly stable red/NIR afterglow.

Spatial Distribution Characteristics and Relationships of Salt-Based Ions and Nutrients in Old Protected Vegetable Fields

To achieve a scientific and objective evaluation of soil acidification, secondary salinization, and nutrient imbalance in old protected vegetable fields (OPVs) with over 30 years of cultivation history, a soil surface breeding vigorous moss was investigated. Here, quantitative laboratory analysis and mathematical statistics were employed to explore the spatial distribution of soil salinity and nutrients, as well as their relationships. The results revealed that OPVs exhibited slightly acidified values. The measured anions and cations in the soil salt composition constituted approximately 77% of the total ions. Among which, Ca2+ was the dominant cation, while SO42− and NO3− were predominant anions. The total water-soluble salt (TDS) content of the surface soil reached 4.52 g kg−1, exceeding the Chinese Saline Soils standard (1.0 g kg−1) by 350%. In the OPVs, nitrate nitrogen was significantly higher than ammonium nitrogen, and available phosphorus and available potassium were generally abundant. Despite exhibited various soil health concerns, a field visit survey presented consistently high and stable yields in OPVs. We hypothesize that this seemingly contradictory finding may be attributable to several factors, including the abundance of divalent cations (Ca2+ and Mg2+), the soil fertility and water retention capacity of unsaturated salt-based suitable soil, as well as good soil aggregate structure. These factors had the potential to reduce the stresses on the soil. This study provided a foundational understanding of the nutrient and salinity status of soils in OPVs, offering valuable data and theoretical groundwork for future research endeavors.

Eumelanin & keratin sourced from waste: unraveling criss-cross functionalities for green electronic applications

Abstract In the framework of the Circular Economy this study provides a detailed analysis of water-based suspensions of two biopolymers derived by sustainable processes: eumelanin from insect farming and keratin from chicken feathers. The latter material was obtained via two different extraction procedures. Colloidal-like suspensions were produced in water either as a single component system or a mixture of both in selected ratios, taking advantage of their high solubility. The suspensions were examined using a comprehensive set of chemical, structural and dielectric techniques to gather information on their properties. Small-Angle x-ray Scattering results provided insights into the elemental polymer sections within the suspension, while Transmission Electron Microscopy images indicate that keratin is the component driving the shape of the aggregation structure in a colloidal environment, and, in some cases, eumelanin internalization. Furthermore, the co-presence of both polymers in water determines the aggregation dimensions and shapes. The discussion focuses on the influence of the aggregation on the dielectric proper-ties by comparing the former to the AC dynamic response returned by Broadband Dielectric Spectroscopy (BDS). Within the BDS framework various items are highlighted including dielectric relaxations, screening effects, counterion condensation and ionic charge transport. The results shown in this work let to foresee the adoption of water or biofriendly aqueous BSF-EuM:Keratin suspensions in the production of devices and sensors with low environmental impact.

On the structure of nanoparticle clusters: effects of long-range interactions.

The fractal structure of aggregates consisting of primary nanoparticles naturally arises during their synthesis. While typically considered to be a fully stochastic process, we suspect long-range interactions, in particular van der Waals forces, to induce an active pull on particles, altering the clustering process. Using an off-grid 3D model, we show that an active pull decreases the density and fractal dimension of formed clusters. These findings could not be reproduced by 2D models, which underestimate screening effects. Additionally, we determined the range within which van der Waals forces dominate the aggregation process.

A mathematical model of the dynamic viscosity dependence of motor oils on temperature, soot concentration, and its morphology

Objectives. A quick cold start of emergency and auxiliary power units based on diesel engines should be possible at any time without problems and in the shortest possible time. The condition of the engine oil is one of the most important factors influencing the smooth start-up of power plants. During diesel engine operation, engine oil accumulates soot in its composition, negatively affecting its rheological properties. The aim of this research is to develop a mathematical model to describe changes in the dynamic viscosity of motor oils as a function of temperature. This model will account for the concentration of soot and its morphology, based on the results of experimental studies.Methods. Standardly used motor oils for diesel engines M-14D2SE and M-5z/14D2SE were used as oil samples in the preparation of model mixtures. The dispersed phase of the suspensions comprised carbon black of the N110, N220, N330, and N220 grades, characterized by a dusty (nongranular) texture. The rheological properties of the samples were determined using a TA Instruments DHR-2 rotational rheometer. The experimental data was subjected to mathematical statistical processing, in order to obtain approximating dependencies.Results. The paper presents an analysis of the various approaches to the description of the rheology of suspensions and the results of experimental studies of the viscosity-temperature characteristics (VTCs) of model samples of oils containing soot. The extant models of the dependence of the dynamic viscosity of suspensions on temperature, volume concentration of the dispersed phase, particle size and shape are demonstrated to be inadequate for the description of the VTCs of motor oils containing soot. A model of the rheological properties of soot-oil suspensions is proposed in the form of a mathematical dependence of their dynamic viscosity on temperature, mass concentration of soot, material density and size of soot particles, characteristics of the shape and structure of primary aggregates and the ratio of the sizes of aggregates and molecules of the dispersion medium.Conclusions. It was demonstrated that a comprehensive description of the VTCs of engine oils containing soot necessitates the consideration of the structural characteristics of the primary aggregates of soot particles. A mathematical model of the VTCs of oils was developed. This model is based on the dependence of the dynamic viscosity of oils on temperature, mass concentration of soot, density of the particle material, degree of non-sphericity of aggregates, the ratio of the particle sizes of the dispersed phase (either aggregates orsingle particles of non-aggregated soot) and oil molecules, and on the structure ofsoot, characterized by adsorption of dibutyl phthalate.

Physical meaning of effective filler content for polyamide-6 based composites

It has been shown that for particulate-filled composites on the base of polyamide-6 at fixed nominal content of filler its effective fraction is defined by particles dispersion degree only. The dependence of the indicated fraction of filler on its aggregates structure serves as alternative description method. The composites properties are controlled fully by reduced (effective) filler content.

The response of soil organic carbon sequestration to organic materials addition in saline-alkali soil: from the perspective of soil aggregate structure and organic carbon component

The response of soil organic carbon sequestration to organic materials addition in saline-alkali soil: from the perspective of soil aggregate structure and organic carbon component

Phenyl- versus cyclohexyl-terminated substituents: comparative study on aggregated structures and electron-transport properties in n-type organic semiconductors

This paper reports that specific attractive intermolecular interactions between side-chain substituents can be useful for enhancing charge-carrier mobility in organic semiconductors owing to the suppression of molecular motions.

Effect of poly(3,4-ethylenedioxythiophene): Poly(styrene sulfonate) aggregate structure on thermoelectric performance

Effect of poly(3,4-ethylenedioxythiophene): Poly(styrene sulfonate) aggregate structure on thermoelectric performance

Mechanism of multiscale structural reassembly controlled by molecular chains during amylase digestion of wheat starch

The digestive characteristics of wheat starch (WS) are closely related to its structure. However, the mechanisms underlying the multiscale structural evolution and reassembly controlled by molecular chains during digestion are poorly understood. To address this issue, amylopectin of wheat starch (APWS) and amylose of wheat starch (AMWS) were separated and digested in vitro. After digestion, chains in WS with a degree of polymerization (DP) < 12 or DP > 37 were degraded, the double-helix content decreased from 58.65 % to 48.77 %, and many particles were degraded. For APWS, the DP > 36 chains increased, the B-type crystallinity increased to 9.55 %, and the particles were transformed into new aggregated structures. For AMWS, the number of 18 < DP < 270 chains was increased, the double-helix content increased from 19.78 % to 37.92 %, the B-type crystallinity increased from 6.65 % to 19.40 %, and a dense granular structure was formed. Overall, our study confirmed that WS, APWS, and AMWS had distinct multiscale structural reassembly mechanisms during in vitro digestion. The DP > 36 chains in APWS and 18 < DP < 270 chains in AMWS were the primary contributors to the formation of enzyme-resistant multiscale structures. This study can serve as a theoretical basis for designing the WS multiscale structure using molecular chains to improve its nutritional value.

Developing chiral aggregates exhibiting anti-S-shaped CD-ee dependence: using a meso-isomer to tune dynamic aggregates induced by enantiomers.

We report the use of the meso-isomer of tartaric acid, meso-tartaric acid, to tune the chirality of the dynamic aggregates of a perylenebisimide dye bearing boronic acid groups in the presence of enantiomeric L-/D-tartaric acid. The CD-ee dependence changes from S- to anti-S-shaped. A change in the structures of the chiral aggregates led by the meso-tartaric acid is identified.

Directionally arranged flexible bamboo/rubber materials with high cushion performance.

Composites derived from plant fibers are promising reinforcing materials for engineering because of their renewable and easily available characteristics. In this study, a simple pretreatment method was developed to fabricate structurally intact bamboo cellulose scaffolds. Water-stable, flexible, impact-resistant, and high damping ratio bamboo-based rubber composites were synthesized using carboxylated styrene-butadiene latex-impregnated 3D bamboo scaffolds. The composites were prepared by "Ethanol dehydration-delignification-polymer redistribution" strategy. The bamboo cellulose aggregate state structure and multiple crosslinked networks in the composite systems endowed the composites with strong mechanical and damping properties. The prepared composites had a high tensile strength, 67 times that of pure rubber (101.58MPa and 1.25MPa), which is higher than that of reported polymer-based vibration-damping materials, and the hydrostability was also significantly improved. The composites exhibited the characteristic viscoelasticity of polymers, with a recovery angle of 132° after 1000 extreme 180° flexion tests. More importantly, composites maintain a higher effective damping factor (Tan δ=0.5) at room temperature. These bamboo-based rubber composites with excellent comprehensive performances have great potential for engineering applications, particularly for vibration damping, lightweight design, and flexible materials.