Lamellar Thickness Research Articles

Templating effect of monoglycerides in controlling the spatial distribution of solid fat crystals within double emulsions.

The spatial distribution of fat crystals significantly impacts the stability and digestion properties of emulsions. This study investigated the templating effect of monoglycerides in controlling the spatial distribution of solid fat crystallization within double emulsions. Double emulsions were formulated with glyceryl monostearate (GMS), glyceryl monolaurate (GML), glyceryl monooleate (GMO), beeswax (BW), glyceryl distearate (GDS), and glyceryl tristearate (GTS) in the oil phase. Monoglycerides influenced the spatial distribution pattern of BW crystals, while minimally affecting GDS and GTS. Cooling at 4°C increased interfacial crystallization without altering distribution patterns. Monoglycerides raised the onset and peak crystallization temperatures and enthalpy in BW emulsions, with GMS showing the most significant effects. Adding GMS slowed nucleation rates and extended induction times, promoting interface crystallization. The templating effect also reduced crystal lamellar thickness, facilitating the transition from β-crystalline to β' crystalline in BW. These findings provide insights into selecting crystallizing emulsifiers and enhancing double emulsion stability.

Crystallization and multiple melting behavior of oriented thick lamellae in isotactic polypropylene

Crystallization and multiple melting behavior of oriented thick lamellae in isotactic polypropylene

Stretching-Regulated Homogenization of Lamellae Thickness in Biaxially Oriented Polypropylene Capacitor Films, and Its Effect on Breakdown Strength.

Stretching fields give rise to the formation of reinforcing crystalsin biaxially oriented polypropylene capacitor films, endowing them with excellent electrical properties. In this paper, the correlation between stretching temperature, ratio, and annealing temperature and film structure as well as electric breakdown strength (Eb) during biaxial stretching is investigated. Synchronous biaxial stretching ensures that the orientation of the prepared films is isotropic. However, the changes caused by the stretching field occur in the lamellae structure, with a gradation of thick and thin lamellae. First, an increasing stretching ratio leads to the homogenization of the crystal toward thick lamellae, increasing Eb. Second, the onset melting temperature (Tonset) is the key to the gradation of thick and thin lamellae. Stretching near or above Tonset results in a reduced order of the recrystallization precursors and forms thin lamellae,degradingEb. Additionally, annealing below the melting point promotes chain migration, which facilitates the homogenization to thick lamellae and improves Eb. In conclusion, the improvement of Eb is related to the homogenization of lamellae thickness. These results provide new insights for optimizing film processing and crystal structure to enhance electrical insulation.

Melatonin maintains the quality and cell wall structure of plum fruits under low temperature storage

To enhance the quality of plum fruits under low temperature storage, the impact of melatonin (MT) treatment (100 μmol L−1) on the quality and cell wall structure of plum fruits under low temperature storage (at 4 °C for 28 days) was examined. The results showed that the contents of total soluble solids, total sugar, titratable acid, and vitamin C in plum fruits treated with MT were higher than control under low temperature storage, and MT helped to prevent pulp browning and maintained the overall quality of the fruits. In addition, MT inhibited the conversion of ion-binding pectin and covalently-bound pectin of plum fruits into water-soluble pectin under low temperature storage. It also decreased the activities of pectin methylesterase, polygalacturonase, β-galactosidase, and endo-β-1, 4-glucanase, while increasing the activities of xyloglucan endotransglycosylase/hydrolase and α-l-arabinofuranosidase. Correlation analysis showed that the fruit hardness and pulp hardness were positively correlated with the covalently-bound pectin content, hemicellulose content, and cellulose content, and negatively correlated with the water-soluble pectin content, ion-binding pectin content, pectin methylesterase activity, β-galactosidase activity, and endo-β-1, 4-glucanase activity. Moreover, the cell structure of plum fruits treated with MT remained more intact and tightly arranged under low temperature storage, with slower degradation of the middle lamella and higher cell wall thickness. This was beneficial for maintaining the integrity of the cell wall structure and inhibiting the increase of intercellular spaces. In conclusion, MT can maintain the quality and cell wall structure of plum fruits, inhibit cell wall degradation, and slow down the decrease in fruit hardness under low temperature storage.

Structural and physicochemical properties of pea starch dual-treated with dry heating and galactomannans.

The research on the combination of starch and galactomannans (GM) with dry heat treatment (DHT) is currently insufficient, which hinders the starch application. In this study, the impacts of dry heat treatment and GM complex on the structural, gelatinization properties, and digestibility of pea starch (PS) were investigated. The gelatinization viscosity and gel hardness of dry heated-PS were decreased. Moreover, the relative crystallinity of PS was improved when individually treated by dry heating and GM complex, resulting in the decline of digestibility. Besides, the long molecular chains (DP ≥ 37) proportion and the semi-crystalline lamellae thickness of the PS-GM-DHT complex were increased, which was relevant to the ratio of galactose/mannose residues in galactomannan. In particular, PS was more prone to complex with locust bean gum following dry heat treatment, which has the highest mannose ratio. The present study provided the fundamental information to promote the starch application further.

γ-irradiation of wheat flour dough: The influence of starch hierarchical structure and physicochemical properties

Irradiation has been shown to cause a change in physicochemical properties and starch depolymerization of wheat flour. However, the impact of starch hierarchical structure and physicochemical properties on dough's viscoelastic behavior during irradiation treatment remains unexplored. Therefore, this study investigated the effect of γ-irradiation (0, 5, 10, 15, and 20 kGy) on the viscoelastic properties of dough and the hierarchical structure and physicochemical characteristics of starches isolated from irradiated dough. Irradiation weakened the gluten network structure and decreased the starch-gluten interaction. Moreover, irradiation reduced the dough's elasticity, viscosity, deformation-resistant capacity, hardness, springiness, cohesiveness, and resilience. Irradiation treatment disrupted the short-range ordered structure, reduced the crystalline lamellae thickness and crystallinity, and dissociated the double helix structure of starch, thus increasing solubility and decreasing peak, trough, and final viscosities. Correlation analysis revealed that the lamellar structure, crystalline structure, short-range ordered structure, and pasting viscosities of starch were the key factors affecting the dough's viscoelastic properties during irradiation treatment.

Solution Strengthening and Short-Range Order in Cold-Drawn Pearlitic Steel Wires

Pearlitic steel rods are subjected to cold-drawing processes to produce pearlitic steel wires with true strains ranging from 0.81 to 2.18. Tensile tests are utilized to attain mechanical properties of cold-drawn pearlitic steel wires. TEM and XRD investigations were performed on the microstructure of the cold-drawn steel wires. With an increasing cold-drawn strain, both the interlamellar spacing and cementite lamellae thickness decrease, while the dislocation density significantly increases. The drawn wire has a tensile strength of 2170 MPa when the true stain reaches 2.18. Deformation-induced cementite dissolution occurs during cold-drawing progress, which releases many C atoms. The findings indicate that the supersaturation of C is heterogeneously distributed in the ferrite matrix. The ordered distribution of the released C in ferrite phases creates short-range order (SRO). SRO clusters and disordered Cottrell atmospheres contribute to solution strengthening, which, together with dislocation strengthening and interlamellar boundary strengthening, form an effective strengthening mechanism in cold-drawn pearlitic steel wires. Our work provides new insights into carbon redistribution and the mechanism of solution strengthening within ferrous phases.

Plastic strain localization in Bouligand structures

The Bouligand structure represents helicoidal stacking of aligned fibers; such a structure is widely observed in biological composites. Despite the progress in characterization of toughening caused by Bouligand arrangement of fibers, the inelastic deformation mechanisms of this structure remain elusive. In this study, we carry out calculations for plastic deformation of Bouligand structure, crossed-lamellar structure and the single lamellar structure. It is found that the single lamellar structure and crossed-lamellar structure can undergo necking, while in the Bouligand structure, plastic strain localization bands develop, which is accompanied by plastic rotating of fibers, lamellar twisting and lamellar delamination. Compared with crossed-lamellar structure, the Bouligand structure exhibits lower plastic energy dissipation. However, the Bouligand pattern can activate delamination of lamellae, generating high level of damage energy dissipation. The plastic deformation of Bouligand structure depends on the fracture properties of interface between adjacent lamellae. It is identified that the plastic dissipation of Bouligand structure increases with increasing cohesive strength of lamellar interface, and dominant shear bands emerge in the case of weak lamellar interface. The high strength of lamellar interface plays a role in promoting twisting of lamellae. We have further revealed the effect of the thickness of individual lamella on plastic deformation of the Bouligand structure. The thick lamella is capable of suppressing plastic strain localization in Bouligand structure, thereby giving rise to high plastic dissipation. The findings of this study shed new light on the development of bioinspired Bouligand-type materials.

Quantitative Analysis of TPU Microstructure and Performance Optimization across Various Processing Conditions.

Thermoplastic polyurethane (TPU) is essential in resource exploration, healthcare, automotive, and high-end recreational sports. Despite extensive research on TPU's microstructures and their macroscopic properties, the impact of processing conditions like compression and injection molding remains underexplored. This study investigates the influence of processing conditions on TPU by preparing samples with varying hard segment contents using compression molding at 205 °C and injection molding at melt temperatures of 205, 210, 215, and 220 °C, followed by heat treatment at 120 °C for 12 h. Results indicate that injection-molded TPU at 205 °C exhibits lower hydrogen bonding, crystallinity, long period, interfacial thickness, and lamella thickness than compression-molded TPU, leading to higher Young's modulus but lower elongation at break. As melt temperatures increase, these microstructural parameters decrease, reducing Young's modulus and increasing elongation at break. Post heat treatment, microstructural parameters increase, aligning Young's modulus with that of compression-molded samples, while elongation at break surpasses them. This suggests that heat treatment enhances microphase separation by rearranging hard and soft segments. our research reveals a consistent pattern across TPUs with varying hard segment contents, indicating that adjusting processing parameters can effectively regulate microstructure and performance, offering valuable insights for developing high-performance polyurethanes.

Sporoderm development in Populus L. (Salicaceae)

Populus is the most genetically studied woody plant. Its pollen is highly distinctive. The sporoderm development from meiosis to mature pollen grains has not been studied for any Populus species. Here we present a detailed ontogenetic study with dates and durations of all stages of sporoderm development for Populus species growing in the Moscow region. They are one native species (Populus tremula), one introduced species (Populus alba), and two widespread cultivars (Populus × nevensis and Populus × berolinensis). Pollen development of P. alba, P. × nevensis, and P. × berolinensis is two weeks earlier than that of P. tremula. Simultaneous meiosis in Populus takes place in late February–early March. It lasts for about a week. In one month the pollen grains mature. The most rapid are the stages of the tetrad period. Orbicules and a peritapetal membrane have been found in the plasmodial tapetum. A thin and often intermittent two-layered exine is formed along the entire circumference of the pollen grain. A tectum (with nanoechini and perforations), columellae and a thin foot layer form the ectexine. The endexine consists of short, thick lamellae. The formation and maturation of all five layers takes one to two weeks. The two-layered intine is the thickest sporoderm layer. Its development takes two to three weeks. Tubular elements are found in the outer intine, making the intine similar to the aperture membrane. Morphologically, Populus pollen grains are inaperturate in the exine and omniaperturate in the intine.

Direct numerical simulation of coalescence and separation of binary droplet collision with lamella stabilization

Binary droplet collision is a fundamental aspect of various natural phenomena and industrial applications. In this work, direct numerical simulation of coalescence and separation of binary droplet collision is performed over a wide range of Weber numbers and impact factors. The incompressible Navier–Stokes equations are solved by the finite volume approach, coupled with the volume of fluid method. To address the inaccurate prediction of thin lamella in simulation, a lamella stabilization method is introduced to resolve the lamella by adjusting the grid resolution. Compared with experimental data, it is validated that the lamella can be accurately and fully captured with this lamella stabilization method. Moreover, the analysis of shape and energy during the collision is conducted, and the variation of lamella is described in detail, particularly the evolution of the thickness of lamella. The results suggest that for obtaining the full variation of lamella, the maximum refinement size of the grid can reach D/4096. It is also found that without lamella stabilization, excessive dissipation can lead to the failure of predicting coalescence and separation, especially for the cases in the transition between coalescence and separation. Furthermore, even if the same collision outcome can be obtained without lamella stabilization, the number and size of droplets have obvious differences.

Crystallization-Controlled Structure and Thermal Properties of Biobased Poly(Ethylene2,5-Furandicarboxylate).

Crystallization-controlled structure and thermal properties of biobased poly(ethylene 2,5-furandicarboxylate) (PEF) were studied. The cold-crystallization temperature controlled the structure and thermal properties of the biobased PEF. The melting was complex and evidenced the presence of a significant fraction of less-stable crystals with a low melting temperature that linearly increased with Tc, which formed already during the early stages of crystallization, together with those melting at a higher temperature. Low Tc resulted in the α'-phase formation, less crystallinity, and greater content of the rigid amorphous phase. At high Tc, the α-phase formed, higher crystallinity developed, the rigid amorphous phase content was lower, and the melting temperature of the less-stable crystals was higher; however, slight polymer degradation could have occurred. The applied thermal treatment altered the thermal behavior of PEF by shifting the melting of the less stable crystals to a significantly higher temperature. SEM examination revealed a spherulitic morphology. A lamellar order was evidenced with an average long period and small average lamella thickness, the latter about 3-3.5 nm, only slightly increasing with Tc.

Micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables

The outstanding combination of high strength and ductility of bridge cable steel wire is attributed to the cold drawing process with intermediate equivalent strain. However, the micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables is not well understood. In this study, defects-controlled deformation in nano-scale interfaces between ferrite and cementite phases with heavily cold drawing process was investigated using high-resolution transmission electron microscopy and molecular dynamics simulation. The excessive thinning of the cementite lamellar thickness observed from the morphology suggested the evolution of the Fe3C/Fe interface in the cold-drawn wires, namely, the partial cementite deformation during the drawing process. Drawing strain played a major role in the occurrence of partial cementite nano-crystallisation. This was because the change in cementite morphology was the primary cause of cementite free energy increase, which ultimately led to cementite phase instability. The decrease of yield strength during the drawing process of the bridge cable steel wire was caused by the inverse Hall-Petch effect resulted from the nodule rotation. When the nodule morphology became flat, the inverse Hall-Petch effect was suppressed. At this time, the strengthening mechanism caused by cementite nano-crystallisation ensured the improvement of tensile strength of steel wire when the dislocation density was close to saturation.

Supramolecular structure and in vitro digestive properties of plasma-treated corn starches varying in amylose content

The effects of plasma treatment on the multi-scale structure and in vitro digestibility of maize starch with different amylose contents were systematically evaluated. The results demonstrated that all maize starches' molecular weights (MW) decreased when treated with plasma, among which the MW of waxy maize starch displayed the largest reduction. Plasma treatment led to an increase in the thickness of the semi-crystalline lamellae and double helix proportions of waxy and normal maize starches. However, high-amylose maize starch presented a less ordered structure by plasma treatment. Additionally, larger pores and channels were observed on the surface of plasma-treated waxy and normal maize starch granules. Moreover, deposits were displayed on the surface of high-amylose maize starch granules. These changes increased the in vitro digestibility and hydrolysis rate of three starches after plasma treatment. Notably, plasma treatment caused diverse alterations in the structure and functionality of maize starch varying in amylose content, leading to maize starch with better digestibility, therefore being used as an ingredient for functional foods.

The multi-scale structure and in vitro digestive kinetics of underutilized Chinese seedless breadfruit starch

In our previous research, the significant difference of physiochemistry properties for underutilized starches was showed between Chinese seedless breadfruit species and the other species. Based on this, the multiscale structure and digestion kinetics of Chinese seedless breadfruit of Spice and Beverage Research Institute species (SBS) and Xinglong species (XBS) was further researched. The SBS exhibited higher α-1,6 glycosylic bond content, free side-chain groups content, double-helix content, homogeneity, molecular weight, and V-type polymorphism, and fewer amorphous content, blocklet sizes, and a smaller semi-crystalline lamella thickness than XBS. Additionally, SBS showed higher final viscosity, pasting temperature, and gelatinization enthalpy than those of XBS. Consequently, SBS display lower rate constant (0.73 h−1) and glycemic index (65.17) than those of XBS (0.86 h−1 and 73.95). The anti-digestibility mechanism was revealed by the structure-digestibility relationship. It was found that resistant starch of SBS and XBS were significantly higher than those of starch from American and African species. This indicated that Chinese breadfruit starch could be considered as a good source of resistant starch, regulating glycemic index. In summary, XBS and XBS could be considered as a well source of resistant starch to make foods for preventing or improving type II diabetes or hyperlipemia.

The effects of UV aging process on the structure and properties of high-tenacity poly(ethylene terephthalate) industrial fiber

The high-tenacity poly(ethylene terephthalate) (HT PET) industrial fibers (1100 dtex/192f) were fixed in position with a constant fiber length and subjected to accelerated artificial ultraviolet exposure with temperature of 50 °C to assess their degradation mechanism. The structural evolutions were evaluated using a combination of ex-situ wide-angle X-ray diffraction (WAXD), ex-situ small angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and intrinsic viscosity tests based on the relaxed aged samples after different aging process. The results indicate that the structures and properties evolutions of HT PET industrial fiber under UV aging process can be categorized into three stages. In the pre-aging stage (t ≤ 0.5d), the fiber experiences a slight decline in tenacity and thermal shrinkage properties due to the combined impact of UV radiation and heat treatment. Subsequently, in the mid-aging stage (0.5d < t ≤ 28d), a notable decrease in the fiber's elongation at break is observed, accompanied by visible macroscopic defects arising from photo-oxidative aging on the fiber surface after 16 days of exposure. While the fiber's unit cell and atomic positions remains stable on atomic scale, the lamellar thickness and long period witness a significant reduction owing to high-orientation molecular breakages in the mesophase region. Moreover, rearrangement of molecular chains leads to a reduction in the tilting angle. In the late-aging stage (t > 28d), the degradation rate of mechanical and thermal shrinkage properties of the fiber decelerates, alongside a decline in intrinsic viscosity. These results suggest that the fiber's crystallinity remains unchanged post UV aging, with the deterioration in mechanical properties of HT PET industrial fiber primarily attributed to molecular degradation during UV exposure.

Feasibility of using polymers to improve foam flow performance in vertical pipes: Application to liquid unloading in gas wells

Foam unloading is a cost-effective technique for removing liquid from low-energy gas wells, but it faces challenges due to thefoam stability at the wellbore. Surfactants alone struggle to create and maintain durable foam films under wellbore conditions. Polymers are known to enhance foam stability by increasing lamella thickness and viscosity, however their impact on foam unloading has not been well explored. This study investigates the effects of Xanthan Gum (XG) and Polyvinylpyrrolidone (PVP) polymers on stability and unloading efficiency of the foams made by Alkyl Polyglycoside surfactant. The research evaluates foam stability and examines the bubble size and lamella thickness under varying salinity conditions. Additionally, the study estimates foam unloading efficiency by determining unloaded mass rate, critical gas velocity and Weber number. Results show that polymer concentration, type and molecular weight significantly affect foam morphology and stability. Xanthan Gum at 1000 ppm demonstrated the smallest bubble size and greatest foam stability. This concentration also achieved the highest unloaded mass, 30 % more than the surfactant-only case. Regarding the molecular weight of the polymers, HPVP demonstrated an ability to generate smaller bubbles in comparison with LPVP. Consequently, HPVP exhibited superior performance in liquid unloading, surpassing LPVP by a margin of 8.5 %. The addition of polymers reduced critical gas velocity, with 1000 ppm of XG yielding the lowest value. Initially, the Weber numbers for polymer-stabilised foams were higher than the surfactant-only case (XG: 208.01, LPVP: 17.70, HPVP: 26.38 vs. APG: 2.25) due to the Marangoni effect but decreased during the unloading process (XG: 788.58, LPVP: 1850.26, HPVP: 1702.01 vs. base case: 4046.42), indicating improved stability and performance. Overall, the study demonstrates that polymers can significantly improve foam stability and performance, maintaining foam integrity throughout the unloading process if engineered properly prior to their application.

Microstructure and strength of cold-drawn large strain Fe35Ni35Cr20Mn10 high-entropy alloy

The Fe35Ni35Cr20Mn10 high-entropy alloy wires can achieve a large strain of 8.73 and a section reduction ratio of 99.98 %,and possess a high strength of 1868 MPa via traditional wire drawing. The microstructure evolution and mechanical properties of cold-drawn Fe35Ni35Cr20Mn10 high-entropy alloy are characterized by microstructure observation and tensile test. The results showed that The Fe35Ni35Cr20Mn10 HEA has excellent plastic forming capacity and excellent phase stability during plastic deformation. The Fe35Ni35Cr20Mn10 HEA has excellent continuous drawing ability, the main deformation mechanism is the plane slip and cross slip of the dislocation and the dynamic recovery of the sublamellar layer make the lamellar structure maintain a dynamic equilibrium state, and the lamellar thickness is basically unchanged to support the continuous plastic deformation under high strain conditions. The dynamic balance of coarsening and refining of lamellar structure in the process of plastic deformation is mainly due to the merging of HEA lamellar caused by the movement of trigeminal node induced by strain. Texture evolution showed that the <111> and <100> fiber textures were the stable texture component and the texture component content remained unchanged even under further increased strain. The Fe35Ni35Cr20Mn10 high-entropy alloy wire with high strain of 8.73 possesses excellent strength, and its tensile strength is 1868 MPa at room temperature, which has the largest strain. The dislocations proliferation, lamellar structure refinement and texture strengthening lead to high strength of the Fe35Ni35Cr20Mn10 high-entropy alloy wire.

The potassium storage performance of carbon nanosheets derived from heavy oils

As by-products of petroleum refining, heavy oils are characterized by a high carbon content, low cost and great variability, making them competitive precursors for the anodes of potassium ion batteries (PIBs). However, the relationship between heavy oil composition and potassium storage performance remains unclear. Using heavy oils containing distinct chemical groups as the carbon source, namely fluid catalytic cracking slurry (FCCS), petroleum asphalt (PA) and deoiled asphalt (DOA), three carbon nanosheets (CNS) were prepared through a molten salt method, and used as the anodes for PIBs. The composition of the heavy oil determines the lamellar thicknesses, sp3-C/sp2-C ratio and defect concentration, thereby affecting the potassium storage performance. The high content of aromatic hydrocarbons and moderate amount of heavy component moieties in FCCS produce carbon nanosheets (CNS-FCCS) that have a smaller layer thickness, larger interlayer spacing (0.372 nm), and increased number of folds than in CNS derived from the other three precursors. These features give it faster charge/ion transfer, more potassium storage sites and better reaction kinetics. CNS-FCCS has a remarkable K+ storage capacity (248.7 mAh g−1 after 100 cycles at 0.1 A g−1), long cycle lifespan (190.8 mAh g−1 after 800 cycles at 1.0 A g−1) and excellent rate capability, ranking it among the best materials for this application. This work sheds light on the influence of heavy oil composition on carbon structure and electrochemical performance, and provides guidance for the design and development of advanced heavy oil-derived carbon electrodes for PIBs.

Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation.

The microstructure plays a crucial role in the manufacturing and application of polyacrylonitrile fibers, which serve as precursors for carbon fibers. Synchrotron radiation small angle x-ray scattering (SR-SAXS) is a non-destructive and precise technique for analyzing fiber structures. This study employed one-dimensional SR-SAXS mapping to extract key structural parameters such as periodicity, lamellae thickness, and the extent of amorphous regions, as well as the directional orientation in γ-irradiated, pre-oxidized polyacrylonitrile fibers. The analysis revealed a three-layered structure comprising a surface skin, a transitional layer, and a central core. Notably, the lamellar thickness exhibits a "U"-shaped distribution, while the long-period structures, amorphous regions, and orientational properties demonstrate a "wave-like" pattern. Within this structure, the skin exhibits a higher level of orientation, with the orientation decreasing progressively from the skin toward the core layer. The structure of the layered crystal was further corroborated by the morphological analysis. In addition, molecular simulations were performed to propose the mechanisms underlying the formation of this layered structure. This comprehensive investigation using SR-SAXS and one-dimensional mapping provides detailed insights into the microstructural and morphological characteristics of polyacrylonitrile fibers, which can inform future advancements in material processing and refinement techniques for the production of advanced fibers.