Microscopic Network Structure Research Articles

Effects of zucchini polysaccharide on pasting, rheology, structural properties and in vitro digestibility of potato starch

Zucchini polysaccharide (ZP) has a unique molecular structure and a variety of biological activities. This study aimed to evaluate the effects of ZP (1, 2, 3, 4 and 5 %, w/w) on the properties of potato starch (PS), including pasting, rheological, thermodynamic, freeze-thaw stability, micro-structure, and in vitro digestibility of the ZP-PS binary system. The results showed that the appearance of ZP significantly reduced the peak, breakdown, final and setback viscosity and prolonged the pasting temperature of PS, whereas increased the trough viscosity. The tests of rheological showed that ZP had a damaging effect on PS gels. Meanwhile, the results of thermodynamic and Fourier transform infrared exhibited that the presence of ZP significantly retarded the retrogradation of PS, especially at a higher levels. The observation of the microstructure exhibited that ZP significantly altered the microscopic network structure of the PS gels, and ZP reduced the formation of the gel structure. Besides, ZP postponed the retrogradation process of PS gels. Moreover, ZP weakened the freeze-thaw stability of the PS gel. Furthermore, ZP also can decrease the digestibility and estimated glycemic index (eGI) value of PS from 86.04 % and 70.89 to 77.67 % and 65.22, respectively. Simultaneously, the addition of ZP reduced the rapidly digestible starch content (from 25.09 % to 16.59 %) and increased the slowly digestible starch (from 24.99 % to 26.77 %) and resistant starch content (from 49.92 % to 56.64 %). These results have certain guiding significance for the application of ZP in starch functional food.

Investigation of the viscoelastic evolution of reactive magnesia cement pastes with accelerated hydration mechanisms

Viscoelasticity of reactive magnesia cement (RMC) pastes containing 3 different hydration agents (HCl, Mg(CH3COO)2 and MgCl2) were investigated. Amplitude sweep, frequency sweep and time sweep of RMC pastes were examined within 3 h of hydration. Time-dependent evolution of storage modulus, loss modulus, phase angle, and shear stress were recorded. Measurements of pH, isothermal calorimetry, XRD, TG-DTG and FTIR were used to analyze hydration reaction and products. Addition of hydration agents (HAs) accelerated the growth rate of storage modulus/loss modulus over time. MgCl2 demonstrated the greatest acceleration influence, also reflected in non-destructive structural build-up and buildability related to 3D printing applications. Addition of MgCl2 and HCl advanced the initial setting time of RMC pastes to 100–110 min, during which yield stress reached maximum, and decreased afterwards. Within 3 h of hydration, pastes containing MgCl2 revealed lowest pH, highest heat release and brucite concentration. HAs inclusion precipitated brucite away from MgO particles in the bulk solution, creating a bridge between MgO particles and enabling denser microscopic network structure.

Effects of ε‐polylysine or ε‐polylysine hydrochloride on the pH responsive ι‐carrageenan gel

AbstractThe binding of oppositely charged polyelectrolytes is a well‐known gel strategy, and pH is an important factor affecting the gel properties. In this work, the influence of pH (3, 5, 7, 9, 11) on the rheological and textural properties, molecular structure and micromorphology of binary mixed gels of ι‐carrageenan (IC) and ε‐polylysine (PLL) or ε‐polylysine hydrochloride (PLH) was investigated. The results showed that a change in pH led to a change in the properties of binary mixed gels. The lower the pH, the higher were G′, G″, complex viscosity and gel transition temperature. At the same time, the water holding capacity and gel strength of IC/PLL (IP) and IC/PLH (IPH) were also improved accordingly, and the gel properties of IPH were always better than those of IP. As the pH increased to alkalinity, the density of the gel network structure decreased, the pore size decreased, the pore wall became thinner and the surface smoothed. When the pH dropped into the acidic range, there was a red shift of the hydroxyl group and the sulfate group bands, an enhancement of the hydrogen bonding interaction and a blue shift of the methyl band and the amide I band. At pH 3, the microscopic network structure of IP and IPH were dense and uniform with small pore size, rough surface and thick pore wall. These results showed that the binary mixed gels had better gel properties at pH 3. The results provided a theoretical basis for the preparation of IP and IPH gels, and also enabled a deeper understanding of the mechanism of interaction between polypeptides and carrageenan. © 2023 Society of Industrial Chemistry.

Network Structure and Water Absorption of Soil Moisture Gel by Coarse-Grained Molecular Dynamics Simulations

With the wide application of hydrogel materials in agriculture, forestry, flexible electronics, electronic information engineering, environmental detection, flexible electronics, information science, technology and so on, the development of various new functional hydrogel materials has gradually become one of the research hotspots. At present, the research on hydrogel materials is mainly focused on the preparation of various functional hydrogels by experimental methods, there is no fundamental understanding of the relationship between the “stimulus-response” and its inner microstructures. In this paper, the author uses the molecular dynamics simulation method to study the evolution of the hydrogel’s microscopic network structure, the relationship between microstructure and water absorption of hydrogels in the processes of water swelling and “stimulus-response”. The next generation of new super absorbent, high toughness, high strength and other functional hydrogels could be synthesized by the guide of this study, and these new hydrogels have a promising future to apply in new fields of technology such as flexible electronics, and biological medicine.

Numerical simulation on mass transfer in the bone lacunar-canalicular system under different gravity fields

The bone lacunar-canalicular system (LCS) is a unique complex 3D microscopic tubular network structure within the osteon that contains interstitial fluid flow to ensure the efficient transport of signaling molecules, nutrients, and wastes to guarantee the normal physiological activities of bone tissue. The mass transfer laws in the LCS under microgravity and hypergravity are still unclear. In this paper, a multi-scale 3D osteon model was established to mimic the cortical osteon, and a finite element method was used to numerically analyze the mass transfer in the LCS under hypergravity, normal gravity and microgravity and combined with high-intensity exercise conditions. It was shown that hypergravity promoted mass transfer in the LCS to the deep lacunae, and the number of particles in lacunae increased more significantly from normal gravity to hypergravity the further away from the Haversian canal. The microgravity environment inhibited particles transport in the LCS to deep lacunae. Under normal gravity and microgravity, the number of particles in lacunae increased greatly when doing high-intensity exercise compared to stationary standing. This paper presents the first simulation of mass transfer within the LCS with different gravity fields combined with high-intensity exercise using the finite element method. The research suggested that hypergravity can greatly promote mass transfer in the LCS to deep lacunae, and microgravity strongly inhibited this mass transfer; high-intensity exercise increased the mass transfer rate in the LCS. This study provided a new strategy to combat and treat microgravity-induced osteoporosis.

Structural study of water/alcohol mixtures adsorbed in MFI and MEL porosils

Ethanol and other biofuels produced during biomass conversion must be separated from the fermentation broth (mainly water) before being used as a fuel. This can be addressed by adsorption-based separation using porous materials. The key objective of this study is to obtain a molecular understanding of water and alcohol adsorption in pure-silica zeolites, particularly in silicalite-1 (MFI-type zeolite) and silicalite-2 (MEL-type zeolite). Molecular simulation techniques are used for this purpose. They provide information on the configuration of the fluids, and so the microscopic network structure of the adsorbed polar molecules can be characterized by using a specific criterion of hydrogen bonding formation. We conducted Grand-Canonical Monte Carlo simulations to compute the adsorption isotherms of pure short alcohols and water and from the liquid alcohol/water binary mixtures throughout the composition range. Despite MFI and MEL being structurally very similar, we found differences in adsorption, which are related to the underlying molecular behavior. While water intrusion occurs by applying pressure due to stronger water-water than water–silicalite interactions, notable water adsorption from the mixture occurs first by hydrogen bond formation with the adsorbed alcohols and then by self-association. A higher degree of water clustering in MEL compared to MFI zeolite, promoted by its straight channels, leads to relatively lower uptakes of water in the latter zeolite (in favor of alcohol molecules).

Three-dimensional network FeNi/C composites with excellent microwave-absorbing properties

In this paper, the carbon coated iron nickel nanoparticles were obtained by calcining PVP crosslinked iron nickel oxalate. The morphology, structural composition and microwave-absorbing (MA) properties of the composites were analyzed by various characterization methods. The results show that FeNi/C composites have excellent impedance matching characteristics and MA performance in multiple frequency by virtue of their microscopic network structure. At the same time, through the analysis of loss mechanism, we found that the material has high dielectric loss and magnetic loss characteristics. Under the joint action of various loss mechanisms such as interface polarization and eddy current loss, the material has a high reflection loss (RL) value at different frequency. At a thickness of 3 mm, the sample FNC12 has a minimum RL of − 52.99 dB at 3.6 GHz. The effective absorption bandwidth (EAB) (RL ≤ −10 dB) is 1.81 GHz.

Molecular behavior of fluid gels - the crucial role of edges and particle surface in macroscopic properties.

Fluid gels exhibit unique properties during oral processing and thus are well known in gastronomy as well as for use in dysphagia patients. Agarose fluid gels, which are produced by gelation under shear, in particular, show elastic solid-like behavior at rest but a fluid-like behavior once critical stress is exceeded. In a previous study this special behavior is addressed to the "hairy" structure of the microgel particles - dangling gel parts and chains on the particle surface - which plays a crucial role in the rheological, mechanical and tribological properties of the gels. In this paper, atomic force microscopy (AFM) was used to investigate the underlying microscopic structures and develop a consistent physical model, which relates the irregular particle structures and their heterogonous shape to the experimental observation of the previous studies. One crucial point is the inner structure of the gel particles, which show a dense area in the center, whereas towards the periphery the network and thus the elastic properties change. Agarose gels by forming helices and meshes, which defines the basic length scale for their elastic response in bulk. These properties in turn depend on the concentration and preparation conditions. The present study is meant to address the still prevalent lack of understanding regarding a direct structure-property relationship of these novel fluid gels. Controlling the properties of such fluid gels may play a crucial role in the texture modification of foods and beverages for dysphagia.

Influence of metallic oxide additives on the synthesis and high-temperature dielectric properties of β-Yb2Si2O7

A pressureless solid-liquid reaction method was used to prepare β-Yb2Si2O7 powders in this article. Effects of different metallic oxides (Li2O, MgO and Al2O3) on synthesis process and high-temperature dielectric properties of β-Yb2Si2O7 were systematically studied. Chemical kinetics of synthesis process was calculated, and the apparent activation energy of Yb2O3/SiO2/Li2O, Yb2O3/SiO2/MgO, Yb2O3/SiO2/Al2O3 systems was calculated to be 42.98, 63.48, and 74.33 kJ/mol, respectively, which decreased by 77.3%, 66.5%, and 60.7% compared with that in additives free system. However, the microscopic network structure of intercrystalline glass phase formed by Li2O or MgO was looser than Al2O3 additive, leading to an intense structural relaxation polarization and a sharp increase in dielectric loss. β-Yb2Si2O7 prepared by adding Al2O3 had the best high-temperature dielectric performance. Its dielectric constant was less than 6, and the dielectric loss tangent was less than 2.5 × 10−2 from room temperature to 1200 °C in the range of 7–18 GHz. Such excellent dielectric property gave it the potential to be used as a wave-transmitting component at high temperature.

Effects of Calcium Hydroxide on Quality of Millet Noodles

This paper studied on the effect of calcium hydroxide on thermodynamic properties of millet dough and qualities of millet noodles,and the mechanism was analyzed. The results showed that the addition of calcium hydroxide had significant effects on the hot-water swelling power,pasting property and endothermic enthalpy of millet flour. When adding 0.1% calcium hydroxide,the hot-water swelling power was the highest,and when adding 0.1% calcium hydroxide,the cooking loss was the lowest. However,continuing to add calcium hydroxide,the cooking loss increased. Due to the presence of calcium hydroxide,the starch gelatinization process was accelerated and the endothermic enthalpy was reduced. Moreover,at this time,the sensory quality and texture characteristics of millet noodles were better,comprehensive acceptability was the highest,and the protein aggregation degree was higher. The microscopic network structure of the internal starch gel was more uniform and compact than the pure millet noodles.

W-Com2Vec: A topic-driven meta-path- based intra-community embedding for content-based heterogeneous information network

Heterogeneous information network (HIN) are becoming popular across multiple applications in forms of complex large-scaled networked data such as social networks, bibliographic networks, biological networks, etc. Recently, information network embedding (INE) has aroused tremendously interests from researchers due to its effectiveness in information network analysis and mining tasks. From recent views of INE, community is considered as the mesoscopic preserving network’s structure which can be combined with traditional approach of network’s node proximities (microscopic structure preserving) to leverage the quality of network’s representation. Most of contemporary INE models, like as: HIN2Vec, Metapath2Vec, HINE, etc. mainly concentrate on microscopic network structure preserving and ignore the mesoscopic (intra-community) structure of HIN. In this paper, we introduce a novel approach of topic-driven meta-path-based embedding, namely W-Com2Vec (Weighted intra-community to vector). Our proposed W-Com2Vec model enables to capture richer semantic of node representation by applying the meta-path-based community-aware, node proximity preserving and topic similarity evaluation at the same time during the process of network embedding. We demonstrate comprehensive empirical studies on our proposed W-Com2Vec model with several real-world HINs. Experimental results show W-Com2Vec outperforms recent state-of-the-art INE models in solving primitive network analysis and mining tasks.

Effects of sintering additives on hot corrosion behavior of γ-Y2Si2O7 ceramics in Na2SO4+V2O5 molten salt

Dense γ-Y2Si2O7 ceramics were prepared by moulding and sintering of pure γ-Y2Si2O7 powders synthesized by adding various additives. Effects of sintering additives on hot corrosion behavior of γ-Y2Si2O7 ceramics in Na2SO4 + V2O5 molten salts were systematically investigated. Chemical kinetics of corrosion process was also calculated to illuminate the influence of different additives on chemical stability. Results showed that corrosion reaction started at grain boundary due to the loose microscopic network. When the intercrystalline glass phase was completely etched, the molten salts began to contact Y2Si2O7, forming NaY9Si6O26 and YVO4. Compared with Li2O and MgO, intercrystalline glass phase formed by Al2O3 additive had the most compact microscopic network structure, leading to the best chemical stability. Apparent activation energy for hot corrosion reaction of γ-Y2Si2O7 ceramics in pure Na2SO4, Na2SO4 + 5 wt% V2O5, Na2SO4 + 10 wt% V2O5, Na2SO4 + 15 wt% V2O5 molten salts was calculated to be 408.16, 373.60, 310.62, and 249.63 kJ/mol, respectively.

Two-level modeling of quarantine.

Continuum models of epidemics do not take into account the underlying microscopic network structure of social connections. This drawback becomes extreme during quarantine when most people dramatically decrease their number of social interactions, while others (like cashiers in grocery stores) continue maintaining hundreds of contacts per day. We formulate a two-level model of quarantine. On a microscopic level, we model a single neighborhood assuming a star-network structure. On a mesoscopic level, the neighborhoods are placed on a two-dimensional lattice with nearest-neighbors interactions. The modeling results are compared with the COVID-19 data for several counties in Michigan (USA) and the phase diagram of parameters is identified.

Study on the Structure and Properties of High-Calcium Coal Ash in the High-Temperature Zone of a Blast Furnace: A Molecular Dynamics Simulation Investigation

Molecular dynamics simulations were carried out to study the behavior of high-calcium coal ash in the high-temperature zone of a blast furnace. The radius distribution function, coordination number, structural unit, transform performance, and fluidity were analyzed. The results showed that CaO did not cause significant variation of the Si-O bond length in the aluminosilicate, except when the CaO content reaches 40%. The simulation results indicated that, as the CaO content increases, the transport properties of the coal ash will become better and the viscosity will accordingly be lower. The reason for this phenomenon is that CaO depolymerized the microscopic network structure of the aluminosilicate, which caused more bridge oxygen to convert to non-bridge oxygen, thereby reducing the degree of polymerization of the system. Meanwhile, through the analysis of potential energy, it was also proved that CaO has the function of improving the system energy and reducing stability. Our studies have fully related the viscosity change and microstructure of high-calcium coal ash in the high-temperature zone of a blast furnace.

Ovalbumin-carboxymethylcellulose complex coacervates stabilized high internal phase emulsions: Comparison of the effects of pH and polysaccharide charge density

Protein-polysaccharide complex coacervates self-assembled via electrostatic interactions generally exhibit superior functional properties than the individual biopolymer. Herein, the main objective of this work was to investigate physicochemical properties of complex coacervates formed with ovalbumin (OVA) and carboxymethylcellulose (CMC) with two different charge densities (CMC0.7, CMC1.2) at pH 3.0, 3.5, and 4.0 and the properties of coacervates stabilizing emulsions with a high oil content. The results showed that the contents of protein and polysaccharide in OVA/CMC complex coacevates decreased with the increase of pH, and the microscopic network structure of the complex coacervates changed from compact to loose, which was mainly due to the weakening of the electrostatic attraction between OVA and CMC. With the higher charge density of CMC1.2, the OVA/CMC1.2 complex coacervates exhibited a denser microscopic network structure and higher storage and loss moduli and complex viscosity than OVA/CMC0.7. The stronger electrostatic attraction between OVA and CMC led to poorer oil binding ability and emulsion stability when coacervates were used to prepare emulsions with 80% v/v oil, particularly evident for OVA/CMC1.2 coacervates. With moderate electrostatic attraction at pH 4.0, OVA/CMC coacervates exhibited an outstanding ability to form and stabilize the emulsions. These findings indicate that OVA/CMC complex coacervates can be used as a new option for food texture manipulation and as a stabilizer for high oil phase food systems.

Study on the Relationships between Microscopic Cross-Linked Network Structure and Properties of Cyanate Ester Self-Reinforced Composites.

Bisphenol A dicyanate (BADCy) resin microparticles were prepared by precipitation polymerization synthesis and were homogeneously dispersed in a BADCy prepolymer matrix to prepare a BADCy self-reinforced composites. The active functional groups of the BADCy resin microparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy. The results of an FT-IR curve showed that the BADCy resin microparticles had a triazine ring functional group and also had an active reactive group -OCN, which can initiate a reaction with the matrix. The structure of the BADCy resin microparticles was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From the TEM results, the BADCy resin microparticles dispersed in the solvent were nano-sized and distributed at 40–60 nm. However, from the SEM results, agglomeration occurred after drying, the BADCy resin particels were micron-sized and distributed between 0.3 μm and 0.6 μm. The BADCy resin prepolymer was synthesized in our laboratory. A BADCy self-reinforced composite was prepared by using BADCy resin microparticles as a reinforcement phase. This corresponds to a composite in which the matrix and reinforcement phase are made from different morphologies of the same monomer. The DSC curve showed that the heat flow of the microparticles is different from the matrix during the curing reaction, this means the cured materials should be a microscopic two-phase structure. The added BADCy resin microparticles as reaction sites induced the formation of a more complete and regular cured polymer structure, optimizing the cross-linked network as well as increasing the interplay between the BADCy resin microparticles and prepolymer matrix. Relative to the neat BADCy resin material, the tensile strength, flexural strength, compressive strength and impact strength increased by 98.1%, 40.2%, 27.4%, and 85.4%, respectively. A particle toughening mechanism can be used to explain the improvement of toughness. The reduction in the dielectric constant showed that the cross-linked network of the self-reinforced composite was more symmetrical and less polar than the neat resin material, which supports the enhanced mechanical properties of the self-reinforced composite. In addition, the thermal behavior of the self-reinforced composite was characterized by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). The results of DMTA also establishes a basis for enhancing mechanical properties of the self-reinforced composite.

The Trimerization of Isocyanate-Functionalized Prepolymers: An Effective Method for Synthesizing Well-Defined Polymer Networks.

For the study of polymer networks, having access to polymer networks with a controlled and well-defined microscopic network structure is of great importance. However, typically, such networks are difficult to synthesize. In this work, a simple, effective, and widely applicable method is presented for synthesizing polymer networks with a well-defined network structure. This is done by the functionalization of polymeric diols using a diisocyanate, and their subsequent trimerization. Using hexamethylene diisocyanate and hydroxyl-group-terminated poly(ε-caprolactone) and poly(ethylene glycol), it is shown that both hydrophobic and hydrophilic poly(urethane-isocyanurate) networks with a well-defined network structure can readily be synthesized. By using in situ infrared spectroscopy, it is shown that the trimerization of isocyanate endgroups is clearly the predominant reaction pathway of network formation, supporting the proposed mechanism and network structure. The resulting networks possess excellent mechanical properties in both the dry and in the wet state.

Training and Spontaneous Reinforcement of Neuronal Assemblies by Spike Timing Plasticity.

The synaptic connectivity of cortex is plastic, with experience shaping the ongoing interactions between neurons. Theoretical studies of spike timing-dependent plasticity (STDP) have focused on either just pairs of neurons or large-scale simulations. A simple analytic account for how fast spike time correlations affect both microscopic and macroscopic network structure is lacking. We develop a low-dimensional mean field theory for STDP in recurrent networks and show the emergence of assemblies of strongly coupled neurons with shared stimulus preferences. After training, this connectivity is actively reinforced by spike train correlations during the spontaneous dynamics. Furthermore, the stimulus coding by cell assemblies is actively maintained by these internally generated spiking correlations, suggesting a new role for noise correlations in neural coding. Assembly formation has often been associated with firing rate-based plasticity schemes; our theory provides an alternative and complementary framework, where fine temporal correlations and STDP form and actively maintain learned structure in cortical networks.

The First 0.14-dB/km Loss Optical Fiber and its Impact on Submarine Transmission

We achieved the lowest-ever transmission losses of 0.1419 dB/km at 1560 nm wavelength and 0.1424 dB/km at 1550 nm in a Ge-free silica-core optical fiber. It was an improvement by 4 mdB/km from the previous record realized in 2015. The Ge-free silica core included fluorine co-doping, which helps to reduce disorder in the microscopic glass network structure that causes Rayleigh scattering loss without a significant increase in waveguide imperfection loss. A two-layered polymer coating with an inner layer having lower elastic modulus than before also contributed to the ultralow loss without influence of microbending loss increase even with an enlarged effective area of 147 μm2. The present fiber with ultralow loss and a large effective area benefits an ultralong haul optical transmission system including transoceanic submarine cable systems. We estimate system performance based on the fiber figure of merit theory that the present fiber enables a 0.10 bit/s/Hz increase in spectral efficiency or 7% reduction in the number of repeaters, compared to the previous record-loss fiber.

PH-Ionizable in Situ Gelling Poly(oligo ethylene glycol methacrylate)-Based Hydrogels: The Role of Internal Network Structures in Controlling Macroscopic Properties

The incorporation of charge within in situ covalently gelling poly(oligo ethylene glycol methacrylate) (POEGMA) precursor polymers enables the fabrication of hydrogels that exhibit both pH-responsive swelling and tunable network structures due to multimechanism cross-linking interactions. The gelation times, swelling responses, degradation kinetics, and mechanics of the resulting gels were strongly influenced by both the type of charge(s) incorporated and pH, with both amphoteric gels and anionic gels showing clear evidence of dual network formation. While the amphoteric dual network was anticipated due to charge interactions, the mechanism of the 5-fold enhancement in mechanical properties observed with the anionic gel relative to the neutral gel was revealed by isothermal titration calorimetry and small-angle neutron scattering to relate to the formation of a zippered chain structure based on dipole–dipole interactions. Consequently, rational design of the chemistry and the microscopic network structure...