Fine Network Structure Research Articles

Study on the interaction and gel properties of pork myofibrillar protein with konjac polysaccharides.

Natural myofibrillar protein (MP) is sensitive to changes in the microenvironment, such as pH and ionic strength, and therefore can adversely affect the final quality of meat products. The aim of this study was to modify natural MP as well as to improve its functional properties. Therefore, the quality improvement effect of konjac polysaccharides with different concentrations (0, 1.5, 3, 4.5 and 6 g kg-1 protein) on MP gels was investigated. With a concentration of konjac polysaccharides of 6 g kg-1 protein, the composite gel obtained exhibited a significant improvement of water binding (water holding capacity increased by 7.71%) and textural performance (strength increased from 29.12 to 37.55 N mm, an increase of 8.43 N mm). Meanwhile, konjac polysaccharides could help to form more disulfide bonds and non-disulfide covalent bonds, which enhanced the crosslinking of MP and maintained the MP gel network structure. Then, with the preservation of α-helix structure (a significant increase of 8.11%), slower protein aggregation and formation of small aggregates, this supported the formation of a fine and homogeneous network structure and allowed a reduction in water mobility. During the heating process, konjac polysaccharides could absorb the surrounding water and fill the gel system, which resulted in an increase in the water content of the gel network and enhanced the gel-forming ability of the gel. Meanwhile, konjac polysaccharides might inhibit irregular aggregation of proteins and promote the formation of small aggregates, which in turn form a homogeneous and continuous gel matrix by orderly arrangement. © 2023 Society of Chemical Industry.

Surimi Production from Tropical Mackerel: A Simple Washing Strategy for Better Utilization of Dark-Fleshed Fish Resources

Mackerel (Auxis thazard), a tropical dark-fleshed fish, is currently a viable resource for the manufacture of surimi, but the optimal washing procedure for more efficient use of this particular species is required right away. Washing is the most critical stage in surimi production to ensure optimal gelation with odorless and colorless surimi. The goal of this study was to set a simple washing medium to the test for making mackerel surimi. Washing was performed three times with different media. T1 was washed with three cycles of cold carbonated water (CW). T2, T3, and T4 were washed once with cold CW containing 0.3%, 0.6%, or 0.9% NaCl, followed by two cycles of cold water. T5, T6, and T7 were produced for three cycles with CW containing 0.3%, 0.6%, or 0.9% NaCl. For comparison, unwashed mince (U) and conventional surimi washed three times in cold tap water (C) were employed. The maximum yield (62.27%) was obtained by washing with T1. When varying quantities of NaCl were mixed into the first washing medium (T2–T4), the yield decreased with increasing NaCl content (27.24–54.77%). When washing with NaCl for three cycles (T5–T7), the yield was greatly decreased (16.69–35.23%). Conventional surimi washing (C) produced a yield of roughly 40%, which was comparable to T3. Based on the results, treatments that produced lower yields than C were eliminated in order to maximize the use of fish resources and for commercial reasons. The maximum NaCl content in CW can be set at 0.6% only during the first washing cycle (T3). Because of the onset of optimal unfolding as reported by specific biochemical characteristics such as Ca2+-ATPase activity (0.2 μmol inorganic phosphate/mg protein/min), reactive sulfhydryl group (3.61 mol/108 g protein), and hydrophobicity (64.02 µg of bromophenol blue bound), T3 washing resulted in surimi with the greatest gel strength (965 g.mm) and water holding capacity (~65%), with fine network structure visualized by scanning electron microscope. It also efficiently removed lipid (~80% reduction), myoglobin (~65% reduction), non-heme iron (~94% reduction), and trichloroacetic acid-soluble peptide (~52% reduction) contents, which improves whiteness (~45% improvement), reduces lipid oxidation (TBARS value < 0.5 mg malondialdehyde equivalent/kg), and decreases the intensity of the gel’s fishy odor (~30% reduction). As a result, washing mackerel surimi (A. thazard) with CW containing 0.6% (w/v) NaCl in the first cycle, followed by two cycles of cold water washing (T3), can be a simple method for increasing gel-forming capability and oxidative stability. The mackerel surimi produced using this washing approach has a higher quality than that produced with regular washing. This straightforward method will enable the sustainable use of dark-fleshed fish for the production of surimi.

Translucency mechanism of heat-induced pigeon egg white gel

In this study, the properties of pigeon egg white (PEW) and chicken egg white (CEW) thermal gels were compared, with the aim of revealing the mechanisms involved in the high transparency of PEW thermal gels. Results demonstrated that PEW gels exhibited higher transparency than CEW gels. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis revealed that PEW gels formed a fine chain gel network structure with an average diameter of thermal aggregates (89.84 ± 7.13 nm). The molecular properties of PEW proteins, such as higher content of β-sheet structures (32.73 %), reactive groups (free sulfhydryl groups, hydrophobic groups), and absolute zeta potential (−3.563 mV), were found to contribute to the formation of smaller thermal aggregates during thermal denaturation. The microrheology measurements showed that these features allowed PEW proteins to interact less with each other and form smaller thermal aggregates during thermal denaturation, which facilitated the formation of fine chain gel networks and thus improved the transparency of the gels. The present study initially reveals the molecular basis of the high transparency of PEW thermal gels and provides a theoretical reference for the development of new highly transparent protein materials.

Flow Properties of Entrained Flow Gasifier Fine Slag and Network Structure of its Molten Slag

Flow Properties of Entrained Flow Gasifier Fine Slag and Network Structure of its Molten Slag

Effect of starch content and ultrasonic pretreatment on gelling properties of myofibrillar protein from Lateolabrax japonicus

AbstractTo investigate the protein–starch interactions in myofibrillar protein gels under the ultrasonic pretreatment, the effect of cassava starch content and ultrasonic pretreatment on gelling properties of myofibrillar protein from Lateolabrax japonicus was studied. For the myofibrillar protein–starch (MPS) solutions, the turbidity and elastic modulus increased when the starch content increased from 0% to 8%. For the MPS gels, the hardness, chewiness, gumminess, and water holding capacity increased with the starch content, whereas the cooking loss and whiteness decreased. Starch incorporation promoted the conversion of free water to immobilized water and bound water. The active sulfhydryl content decreased with the starch content, whereas the hydrogen bond and hydrophobic interaction content increased. Fine network structure containing pores at uniform size was formed in the MPS gel at an increased starch content, as shown in the scanning electron microscope images. When the ultrasonic pretreatment was introduced, the elastic modulus of MPS solutions and hardness, chewiness, gumminess, hydrophobic interaction, β‐sheet content, and microstructural compactness of the MPS gels increased, whereas the turbidity of the MPS solutions and cooking loss, whiteness, free water content, active sulfhydryl content, and random coil content of the MPS gels decreased. The MPS gel containing 8% of starch and subjected to ultrasonic pretreatment showed the highest hardness, chewiness, and gumminess of 220, 150, and 160 g, while the lowest cooking loss of 2.5% among all samples. Therefore, the gelling properties of myofibrillar protein from L. japonicus could be enhanced by the starch incorporation, ultrasonic pretreatment, and their synergistic effect.

Characteristic exothermic behavior and short-range ordering in aggregates of ultimately fine fibers made of monodisperse polystyrene

We investigated the thermal behavior and structure formation of electrospun (ES) fiber mats and freeze-dried (FD) foams consisting of very fine fibrous network structure, and compared the results with those of self-standing membranes, in which the motion of boundary molecules is not restrained by contacting solids. We chose monodisperse polystyrene (PS) as a material polymer to examine the molecular weight effect as well. For the ES fibers and FD foams, a characteristic exothermic peak was observed at around 110 °C in DSC curve at 1st scan, while such exothermic peak did not appear for the self-standing films and bulk. To further investigate the nano-periodic structure inside materials during heating, we carried out WAXD measurements. Although the PS used in this study was atactic, the ES fibers formed ordered structure near its glass-transition temperature (Tg). Furthermore, the FD foams exhibited high short-range order even in the unheated state, and the regularity was more developed by heating above 120 °C.

Fabrication of surface modified antibacterial Ti6Al4V alloy powder reinforced gelatin/chitosan composite scaffold for tissue engineering applications

The present work attempted to modify Ti6Al4V (Ti64) alloy powder to induce biocompatibility and antimicrobial properties by incorporating Ca2+ and Ag+ ions, respectively using a simple chemical treatment followed by ion exchange method. Thus functionally modified Ti64 alloy powders characterized using FE-SEM and Raman spectroscopic techniques indicate the formation of fine porous network structure along with the evolution of different phases of titania upon heat treatment in presence of Ca2+ and Ag+ ions. The incorporation of Ca2+ ions and transformation of Ag+ ions into AgNPs and their decoration on the nano porous network structure have been confirmed by the HR-TEM and EDX results. Optimized concentration of AgNPs decorated Ti64 alloy powder not only found to induce antimicrobial activity against both Gram-positive S. aureus and Gram-negative E. coli bacteria and also compatible with MG-63 cell lines. Surface functionalized Ti64 alloy powder was subsequently used as reinforcement for the fabrication of gelatin - chitosan composite scaffolds using the lyophilization technique. Thus fabricated composite scaffold was analyzed for its pore morphology and pore distribution along with its in-vitro cell toxicity towards MG-63 cell lines using MTT assay. Taken together, surface modified Ti64 alloy powder reinforced gelatin-chitosan composite scaffold with biocompatible and antimicrobial properties is expected to be suitable for tissue engineering applications.

Physicochemical properties of wooden breast-extracted myosin and rheological properties of its heat-induced gel.

It is reported that broilers with 'wooden breast' have poor processing properties, such as low binding and water-holding capacities. However, the reason for the poor functional characteristics has not been clarified. In this study, myosin was extracted from a wooden breast. Its physicochemical properties were investigated to clarify the relationship between the structure and physicochemical properties of the heating gel of myosin obtained from the wooden breast. The turbidity of myosin solution extracted from wooden breast increased with increase in the heat treatment to a higher value than that from the normal breast meat myosin. The solubility of myosin collected from a wooden breast after heating decreased like normal breast muscle myosin. The surface hydrophobicity of myosin removed from wooden breast increased continually above 60 °C, unlike the change in surface hydrophobicity of normal breast myosin. The free thiol group of myosin extracted from the wooden breast was higher than normal breast myosin before and after heating. The apparent elasticity of heat-induced gels and chicken meat sausages was significantly lower in sausages and gel with wooden breast than normal ones (P < 0.05). The microstructure of the heated gel of normal myosin showed a fine network structure. In contrast, the heat-induced gel of wooden breast-extracted myosin showed a structure with loosely connected aggregates and many gaps. The coarseness of the internal gel structure of myosin extracted from wooden breast was shown to affect the apparent elasticity of the gel and sausages made from the chicken meat. © 2023 Society of Chemical Industry.

Fine temporal brain network structure modularizes and localizes differently in men and women: insights from a novel explainability framework.

Deep learning has become an effective tool for classifying biological sex based on functional magnetic resonance imaging (fMRI). However, research on what features within the brain are most relevant to this classification is still lacking. Model interpretability has become a powerful way to understand "black box" deep-learning models, and select features within the input data that are most relevant to the correct classification. However, very little work has been done employing these methods to understand the relationship between the temporal dimension of functional imaging signals and the classification of biological sex. Consequently, less attention has been paid to rectifying problems and limitations associated with feature explanation models, e.g. underspecification and instability. In this work, we first provide a methodology to limit the impact of underspecification on the stability of the measured feature importance. Then, using intrinsic connectivity networks from fMRI data, we provide a deep exploration of sex differences among functional brain networks. We report numerous conclusions, including activity differences in the visual and cognitive domains and major connectivity differences.

High‐strength, ultrastretchable hydrophobic association hydrogel reinforced by tailored modified carboxymethyl cellulose

AbstractA new pathway to construct high‐strength, ultrastretchable hydrogels based on tailored modified carboxymethyl cellulose (TMCMC)and hydrophobic association(HPA) system was investigated. TMCMC was prepared from degradation of carboxymethyl cellulose (CMC)/N,N′‐methylene bisacrylamide (MBA) chemical cross‐linked hydrogels. The residual double bonds of TMCMC, confirmed by 1H‐NMR and FTIR analysis, reacted with acrylamide in HPA to form TMCMC/HPA hydrogels, and the homogeneous and fine spatial network structure of TMCMC/HPA hydrogel could be observed by scanning electron microscopy. Rheological analysis revealed that the coexistence of physical and chemical crosslinking in TMCMC/HPA hydrogels. Further studies showed that TMCMC/HPA hydrogel with MBA content of 0.5 wt% has outstanding mechanical properties, and its fracture stress, elongation and tensile strength reach 1.17 MPa, 3717.05% and 15.68 MJ·m−3, respectively. Moreover, the hydrogel displayed good swelling resistance and stable strain electrical signal response.

Glass Microchannel Formation by Mycelium

We propose a new method to fabricate complicated 3-dimensional glass microchannels. We employed mycelium for this purpose. Mycelium possesses a complicated, fine and three-dimensional network structure. We cultivated mycelium in silica compounds, and subsequently silica compounds were heated to be sintered. During this heating process, all the mycelium was burned off and remained a fine network channel structure in a transparent glass chip. We also tried to control of the growth of this mycelium. The growth could be changed by growth conditions. In this work, we used cyclic mechanical stimuli for this purpose. We set cyclic tensile strain to the sample under growing mycelium. This cyclic strain caused anisotropic growth of the mycelium in some condition.

Improved mechanical properties of in situ microfibrillar polypropylene/polyamide6 composites through constructing strong interfacial adhesion

In situ fibrillation technology can effectively improve the mechanical properties of low compatibility polymer blends, but the enhancement effect is greatly reduced due to the weak interfacial adhesion of such blends. In this work, a novel compatibilizer polypropylene grafted graphene oxide was synthesized and added to a typical low compatibility blends polypropylene/nylon 6 by a two‐step method. Comparing with no compatibilizer or adding traditional compatibilizer by a one‐step method, polypropylene grafted graphene oxide not only enhances the fibrils strength, but also reduces the interfacial tension, resulting in a fine and uniform network structure of polypropylene. Especially the profiled fibrils with a large number of nodules on the surface were obtained, which can increase the interfacial adhesion. With the addition of 0.6 wt% of polypropylene grafted graphene oxide, the tensile and flexural strength of the blends were enhanced by 19.77% and 42.19%, respectively, compared with pure polypropylene This enhancement effect is 3‐16% higher than adding traditional compatibilizer (2.5‐8 wt%) by a one‐step method. Furthermore, the maximum tensile strength of in situ microfibrillar polypropylene/polyamide6 composites correlated with the rheological gel points by adding polypropylene grafted graphene oxide. This study sheds light on the preparation of in situ microfibrillar composites with high mechanical strength and broadens the effective way of reinforcing universal plastics with engineering plastic.

Fabrication of disk-shaped, deuterated resorcinol/formaldehyde foam target for laser–plasma experiments

Abstract Resorcinol/formaldehyde (RF) foam resin is an attractive material as a low-density target in high-power laser–plasma experiments because of its fine network structure, transparency in the visible region, and low-Z element (hydrogen, carbon, and oxygen) composition. In this study, we developed disk-shaped RF foam and deuterated RF foam targets with 40–200 μm thickness and approximately 100 mg/cm3 density having a network structure from 100 nm to a few micrometers cell size. By deuteration, the polymerization rate was drastically slowed down owing to kinetic isotope effects. These targets were used in high-power laser experiments where a megaelectronvolt proton beam was successfully generated.

Development of an antimicrobial bioactive paper made from bacterial cellulose

Bacterial cellulose (BC) has emerged as an attractive adsorptive material for antimicrobial agents due to its fine network structure, its large surface area, and its high porosity. In the present study, BC paper was first produced and then lysozyme was immobilized onto it by physical adsorption, obtaining a composite of lysozyme-BC paper. The morphology and the crystalline structure of the composite were similar to that of BC paper as examined by scanning electron microscopy and X-ray diffraction, respectively. Regarding operational properties, specific activities of immobilized and free lysozyme were similar. Moreover, immobilized enzyme showed a broader working temperature and higher thermal stability. The composites maintained its activity for at least 80 days without any special storage. Lysozyme-BC paper displayed antimicrobial activity against Gram-positive and Gram-negative bacteria, inhibiting their growth by 82% and 68%, respectively. Additionally, the presence of lysozyme increased the antioxidant activity of BC paper by 30%. The results indicated that BC is a suitable material to produce bioactive paper as it provides a biocompatible environment without compromising the activity of the immobilized protein. BC paper with antimicrobial and antioxidant properties may have application in the field of active packaging.

Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness

Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

Molecular forces and gelling properties of heat-induced gel from egg white protein glycated with isomalto-oligosaccharide

Glycation with fructo-oligosaccharide (FO) and isomalto-oligosaccharide (IMO) was employed to improve the heat-induced egg white protein (EWP) gels. Results showed that EWP glycated with IMO exhibited a greater degree of glycation (DG) and better gelling properties than those of FO-EWP conjugates. The electrophoresis and liquid chromatography mass spectrometry (LC-MS) indicated that IMO was successfully covalently cross-linked with EWP. Fourier transform infrared spectroscopy (FTIR) showed that the glycation increased the percentages of intramolecular and intermolecular β-sheets of EWP and lowered the contents of 310-helical structure. The rheological test indicated that the gel-forming temperature of EWP was brought forward with the increase of glycation time. Furthermore, the glycation could induce the formation of EWP gel characterized by the higher strength of hydrogen bonds and hydrophobic interactions and lower strength of disulfide bonds. The changes of intermolecular forces resulted in a fine network structure of EWP gel, which significantly enhanced the fracture strength, bound water relaxation proportion and water-holding capacity (WHC) of the gel. A positive correlation existed in the WHC and gel fracture strength. This study proved that glycation with IMO efficiently improved the gelling properties of EWP.

Influence of cyclodextrins on the gel properties of kappa-carrageenan

The influence of cyclodextrins (CDs) on the rheological and structural properties of κ-carrageenan (κ-CA) gel was investigated. Gelling temperature (Tg) of κ-CA was improved by CDs present in the system. Variation of the Herschel-Bulkley model parameters indicates that the addition of CDs increases plasticity of the κ-CA sol. Scanning electronic micrographs show that networks of κ-CA become flat and firm after CDs were added. κ-CA gel containing methyl-β-CD shows the most uniform and fine network structure. Moreover, a proposed model of CDs in κ-CA phase was provided. The influence of CDs on κ-CA gelation was mainly through (i) the exclusion of CDs from κ-CA in the sol state, (ii) the regular rearrangement of κ-CA random coils influenced by CDs in the sol state, (iii) the binding of CDs to the κ-CA surface by hydrogen bonds in the gel.

Advanced easySTED microscopy based on two-photon excitation by electrical modulations of light pulse wavefronts.

We developed a compact stimulated emission depletion (STED) two-photon excitation microscopy that utilized electrically controllable components. Transmissive liquid crystal devices inserted directly in front of the objective lens converted the STED light into an optical vortex while leaving the excitation light unaffected. Light pulses of two different colors, 1.06 and 0.64 μm, were generated by laser diode-based light sources, and the delay between the two pulses was flexibly controlled so as to maximize the fluorescence suppression ratio. In our experiments, the spatial resolution of this system was up to three times higher than that obtained without STED light irradiation, and we successfully visualize the fine microtubule network structures in fixed mammalian cells without causing significant photo-damage.

Actin Remodeling in Regulated Exocytosis: Toward a Mesoscopic View.

Cellular communication relies on fusion of secretory vesicles with the plasma membrane, following dynamic events that change the micro- and nanoscale environment of the approaching vesicles in the vicinity of docking sites. Visualization of fine cortical actin network structures and their interactions with vesicle and plasma membrane has recently been facilitated by the development of new imaging technologies. Consequently, a greater understanding is emerging of the role of the cortical actin network on controlling secretory vesicles as they undergo docking, priming, and fusion in exocytic hot spots. In this review, we propose a mechanistic framework underpinning the mesoscopic properties of the cortical actin and discuss how molecular coupling of these pleiotropic effects orchestrate every single step of regulated exocytosis.

Synthesis of layered double hydroxide/poly(N-isopropylacrylamide) nanocomposite hydrogels with excellent mechanical and thermoresponsive performances.

Nanocomposite (NC) hydrogels of positively charged layered double hydroxide (LDH) single-layer nanosheet (SLNS) cross-linked poly(N-isopropylacrylamide) (PNIPAM) were synthesized. Especially, the LDH SLNSs used here were pre-synthesized via an aqueous synthetic route without using organic solvents and modifiers. The obtained LDH/PNIPAM NC hydrogels were characterized using XRD, SEM, TEM, and DSC. The mechanical and thermoresponsive properties were determined using tensile, compression, and swelling/deswelling tests. Interestingly, different network structures are observed for the NC hydrogels along the horizontal and vertical directions; those along the horizontal direction exhibit a fine and uniform sponge-like network structure while those along the vertical direction exhibit a hierarchical layered architecture. Compared with the conventional N,N'-methylene bisacrylamide cross-linked PNIPAM hydrogel, the NC hydrogels exhibit extraordinary deformability and stretchability and obviously improved thermoresponsive swelling/deswelling characteristics. Furthermore, the fracture elongation observed here is obviously higher than those reported for negatively charged clay/PNIPAM NC hydrogels. With the increase in the LDH content from 0.8 to 2.0 wt%, the fracture strength and the compressive strength at an 85% strain increase from 23.5 to 37.2 kPa and from 0.15 to 0.57 MPa, respectively, while the fracture elongation decreases from 2689 to 2202%. The mechanism for the improved mechanical performances of the NC hydrogels is discussed. To the best of our knowledge, this is the first report on LDH/PNIPAM hydrogels. This work provides a green synthesis route for LDH-containing NC hydrogels. The new NC hydrogels may have great potential applications such as in tissue engineering, drug vehicles, and sorbents.