Variation In Strength Research Articles

Holographic spin alignment of J/ψ meson in magnetized plasma

We study the mass spectra and spin alignment of vector meson J/ψ in a thermal magnetized background using a generalized theoretical framework based on gauge/gravity duality. Utilizing a soft wall model for the QGP background and a massive vector field for the J/ψ meson, we delve into the meson’s spectral function and spin parameters (λθ, λφ, λθφ) for different cases, assessing their response to variations in magnetic field strength, momentum, and temperature. We initially examine scenarios where a meson’s momentum aligns parallel to the magnetic field in helicity frame. Our results reveal a magnetic field-induced positive λθH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{\ heta}^{\ extrm{H}} $$\\end{document} for low meson momentum, transitioning to negative with increased momentum. As a comparison, we also study the case of momentum perpendicular to the magnetic field and find the direction of magnetic field does not affect the qualitative behavior for the eB-dependence of λθH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{\ heta}^{\ extrm{H}} $$\\end{document}. Moreover, we apply our model to real heavy-ion collisions for three different spin quantization directions. Further comparisons with experimental data show qualitative agreement for spin parameters λθ and λφ in the helicity and Collins-Soper frames.

Enhanced strength, toughness and reliability in crab exoskeleton–inspired 3D-printed porous thermoplastics

PurposeFused deposition modeling enables multiscale structure control. However, most of this structural space is unexplored. Specifically, the impact of biomimetic porous structures on the mechanical behavior and reliability of common thermoplastics are unclear. In this work, porous structures inspired by the multifunctional crab exoskeleton were 3D-printed with different raster orientations, including fully rotating rasters similar to Bouligand structures found in biological materials. Tensile tests and simulations were performed to observe the stochastic behavior of fracture properties and to reveal the underlying origins of mechanical reliability in biomimetic porous systems.Design/methodology/approachTensile tests were performed on 3D-printed porous structures with four different rasters. These rasters were biomimetic Bouligand, semi-Bouligand, 00 raster and 45°/−45° raster. In addition, two different sets were manufactured to observe the impact of contours on the mechanical behavior. A total of 137 tensile tests were performed. A total of 88 finite element simulations were executed using Abaqus built-in Hashin damage initiation criterion and energy-based damage evolution law. Weibull analyses were performed to quantify the stochastic properties.FindingsBiomimetic Bouligand structure is effective in increasing fracture strength. Average fracture strength of the Bouligand structure was 33% higher compared to the default 45°/−45° and 10% higher compared to 00 rasters. Variations in strength were lower in Bouligand structure compared to the default 45°/−45° raster. However, 00 raster had the highest Weibull modulus m = 54 compared to Bouligand m = 25 and 45°/−45° m = 17. Simulations showed that Bouligand structure is effective in increasing the mechanical reliability through local damage accumulation around the holes. The simulated Weibull modulus of the Bouligand structure was 40 compared to the moduli of other rasters that ranged from 18 to 25.Practical implicationsThe mechanical reliability of porous Bouligand structures is higher compared to other rasters, which makes the biomimetic structure a better choice for industrial applications. Contours decrease the strength and strain at failure for 3D-printed porous structures. Bouligand structures with rotating raster orientations increased strength and strain at failure when contours are present in the porous structure.Originality/valueTo the best of the authors’ knowledge, this is the first study showing the effects of biomimetic raster orientations on the mechanical behavior and the effects of contours on the tensile fracture properties of 3D-printed porous acrylonitrile butadiene styrene using tensile tests and fracture simulations. This is the first study applying composite fracture model to anisotropic porous 3D-printed polymers.

Effect of Dislocation Density on the Dynamic Strength of Aluminium

AbstractThe effects of cold work on dynamic flow strength is studied through measurements of dislocation density and elastic precursor attenuation in shocked aluminium. High-purity aluminium and Al 6082 alloy samples are subjected to up to three passes of rotary swaging, a severe plastic deformation (SPD) technique, in order to produce large variations in starting material conditions. Detailed material characterisation is performed using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) to determine the initial dislocation density, texture, grain boundary density and misorientation distribution. Variations in dynamic strength are studied through the evolution of the elastic precursor amplitude with propagation distance in specimens with thicknesses between 0.2 and 1 mm, shock loaded to impact stresses of about 4.6 GPa. It is shown that dynamic strength decreases with increasing initial dislocation density in both materials, demonstrating rare, quantified measurements of a reversal in the effect of dislocation density on yield strength at strain rates around 10$$^{4}$$ 4 s$$^{-1}$$ - 1 and above.

Molecular dynamics simulation of salt diffusion in constituting phosphazene-based polymer electrolyte

A growing demand to visualize polymer models in liquid poses a computational challenge in molecular dynamics (MD) simulation, as this requires emerging models under suitable force fields (FFs) to capture the underlying molecular behaviour accurately. In our present study, we have employed TIP3P potential on water and all atomistic optimized potentials for liquid simulations FFs to study the liquid electrolyte behavior of phosphazene-based polymer by considering its potential use in lithium-ion polymer batteries. We have explored the polymer's local structure, chain packing, wettability, and hydrophobic tendencies against the silicon surface using a combination of a pseudocontinuum model in MD simulation, and surface-sensitive sum frequency generation (SFG) vibrational spectroscopy. The finding yields invaluable insights into the molecular architecture of phosphazene. This approach identifies the importance of hydrophobic interactions with air and hydrophilic units with water molecules in understanding the behavior and properties of phosphazene-based polymers at interfaces, contributing to its advancements in materials science. The MD study uniquely captures traces of the polymer-ion linkage, which is observed to become more pronounced with the increase in polymer weight fraction. The theoretical observation of this linkage's influence on lithium-ion diffusion motion offers valuable insights into the fundamental physics governing the behavior of atoms and molecules within phosphazene-based polymer electrolytes in aqueous environments. Further these predictions are corroborated in the molecular-level depiction at the air-aqueous interface, as evidenced from the OH-oscillator strength variation measured by the SFG spectroscopy.The fundamental findings from this study open new avenues for utilizing MD simulation as a versatile methodology to gain profound insights into intermolecular interactions of polymer. It could be useful in the application of biomedical and energy-related research, such as polymer lithium-ion batteries, fuel cells, and organic solar cells.

Conceptual design and properties of ultra-high residual strength geopolymer after 1000 ℃ thermal exposure

A novel geopolymer concrete is developed, incorporating waste ceramic aggregates, with ultra-high residual strength after exposure to elevated temperatures. Different aggregate volume fractions and particle size gradations are designed, and the variations in mass loss, volume shrinkage, compressive strength, mineral composition, and microstructure of geopolymer mortar after exposure to high temperatures ranging from 20 ℃ to 1000 ℃ are investigated by testing mass loss, volume change, strength, XRD and SEM. The results show that the waste ceramic aggregates (WCA) applied in the preparation of geopolymer mortars improve the mechanical properties and high-temperature resistance. By optimizing aggregate particle size gradation, the microstructure of the geopolymer mortar becomes denser and more homogeneous, and the high-temperature resistance is further improved. The residual compressive strength at 1000 °C is 115.2 MPa, 476 % higher than that of reference. These findings demonstrate the great potential of geopolymer mortars using ceramic aggregates with optimized gradation for high temperature resistant applications.

In vitro investigations on the effects of graphene and graphene oxide on polycaprolactone bone tissue engineering scaffolds

Polycaprolactone (PCL) scaffolds that are produced through additive manufacturing are one of the most researched bone tissue engineering structures in the field. Due to the intrinsic limitations of PCL, carbon nanomaterials are often investigated to reinforce the PCL scaffolds. Despite several studies that have been conducted on carbon nanomaterials, such as graphene (G) and graphene oxide (GO), certain challenges remain in terms of the precise design of the biological and nonbiological properties of the scaffolds. This paper addresses this limitation by investigating both the nonbiological (element composition, surface, degradation, and thermal and mechanical properties) and biological characteristics of carbon nanomaterial-reinforced PCL scaffolds for bone tissue engineering applications. Results showed that the incorporation of G and GO increased surface properties (reduced modulus and wettability), material crystallinity, crystallization temperature, and degradation rate. However, the variations in compressive modulus, strength, surface hardness, and cell metabolic activity strongly depended on the type of reinforcement. Finally, a series of phenomenological models were developed based on experimental results to describe the variations of scaffold’s weight, fiber diameter, porosity, and mechanical properties as functions of degradation time and carbon nanomaterial concentrations. The results presented in this paper enable the design of three-dimensional (3D) bone scaffolds with tuned properties by adjusting the type and concentration of different functional fillers.Graphic abstract

Role of electron withdrawing moieties in phenoxazine–oxadiazole-based donor–acceptor compounds towards enriching TADF emission

Herein, we reported the effect of electron withdrawing units, such as trifluoromethyl (CF3) and cyanide (CN), substitution on a thermally activated delayed fluorescent (TADF) molecule (10-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)-10H-phenoxazine (PXZ-OXD)). The addition of electron withdrawing units has increased the acceptor strength and reduced the interaction between PXZ and OXD, thus reducing the gap between the singlet and triplet states (ΔEST) of excitons. To understand the variation in the acceptor strength of PXZ-OXD as a function of its molecular structure and density of states, density functional theory (DFT) and time-dependent DFT (TDDFT) were conducted. Transition density matrix investigations revealed that the addition of −CF3 and –CN to PXZ-OXD triggers CT excitons, while inducing lower ΔEST values. Particularly, the lowest ΔEST (0.05 eV) with a notable red shift in the emission spectrum was observed with 4′-CF3PXZOXD. The delayed component lifetime of PXZOXD is found to be reduced after the substitution of −CNwhm and −CF3. Despite the weak charge transfer transitions, the substitution of conjugative –CN group is found to be beneficial in improving the HOMO-LUMO overlap with a moderate decrease in reverse intersystem crossing (KRISC), which attained enhancement in the photoluminescent quantum yield. Additionally, the substitution of the above electron withdrawing units on PXZ-OXD yielded a red shift in the electroluminescence spectrum. Furthermore, the external quantum efficiency (at 100 cd/m2, i.e., EQE100) of the 4′-CNPXZOXD-based organic light-emitting diode is found to improve by 21.13 % against the PXZOXD (16.9 %).

Thermomechanical Processing for Improved Mechanical Properties of HT9 Steels.

Thermomechanical processing (TMP) of ferritic-martensitic (FM) steels, such as HT9 (Fe-12Cr-1MoWV) steels, involves normalizing, quenching, and tempering to create a microstructure of fine ferritic/martensitic laths with carbide precipitates. HT9 steels are used in fast reactor core components due to their high-temperature strength and resistance to irradiation damage. However, traditional TMP methods for these steels often result in performance limitations under irradiation, including embrittlement at low temperatures (<~430 °C), insufficient strength and toughness at higher temperatures (>500 °C), and void swelling after high-dose irradiation (>200 dpa). This research aimed to enhance both fracture toughness and strength at high temperatures by creating a quenched and tempered martensitic structure with ultrafine laths and precipitates through rapid quenching and unconventional tempering. Mechanical testing revealed significant variations in strength and fracture toughness depending on the processing route, particularly the tempering conditions. Tailored TMP approaches, combining rapid quenching with limited tempering, elevated strength to levels comparable to nano-oxide strengthened ferritic alloys while preserving fracture toughness. For optimal properties in high-Cr steels for future reactor applications, this study recommends a modified tempering treatment, i.e., post-quench annealing at 500 °C or 600 °C for 1 h, possibly followed by a brief tempering at a slightly higher temperature.

Examining the changes in strength and mechanical property of dynamic stabilizers of the medial elbow joint through repetitive pitching

The flexor-pronator muscles (FPM) and their common tendon (CT) are essential in protecting the medial ulnar collateral ligament against elbow valgus stress during pitching. This study aimed to investigate the effect of repetitive pitching on FPM strength and CT stiffness. Fifteen healthy males (mean age: 21.8 ± 1.3-years-old) with over 5 years of baseball experience performed a series of 100 full-effort fastball pitches. We measured grip and isolated digital flexion strength of the second, third, and fourth digits before and after the pitching task. The decline in muscle strength was determined using the rate of change in muscle strength after pitching relative to that before. CT stiffness was measured using a hand-held myotonometer device at rest and during grip motion at 50% maximum voluntary contraction. The increase in CT stiffness during grip motion relative to rest was calculated as the augmentation rate of CT stiffness. Statistical analyses were performed to compare the changes in grip strength, digital flexion strength, and CT stiffness due to pitching. Additionally, the reduction rate of muscle strength was compared among various strength variables. Correlation coefficients were used to evaluate the relationships between the augmentation rate of CT stiffness after pitching and the reduction rate in any muscle strength. Grip and isolated digital flexion strengths decreased significantly after pitching (P < 0.01). The decline in muscle strength was significantly higher for all isolated digital strengths than that for grip strength (P < 0.05). CT stiffness was augmented with grip motion compared to that at rest pre- and post-pitching (P < 0.001). However, no change in CT stiffness due to pitching was observed, regardless of the grip motion (P > 0.05). Additionally, a lower augmentation rate of CT stiffness after pitching was moderately associated with the greater reduction rate of the second digital flexion strength (r = 0.607, P = 0.016) without other relationships. This study found reduced grip and digital flexion strength after pitching; with no change in CT stiffness. However, given the consequences of correlation analyses, individuals with a more prominent reduction in second digital flexion strength due to pitching were impaired in CT stiffness augmentation after pitching. Digital flexion strength represents the strength of the flexor digitorum superficial; therefore, this study suggests that forearm FPM, particularly the second digit of the flexor digitorum superficial, is an important factor for enhancing CT stiffness.

Synthesis and rheological analyzes of temperature and light sensitive gels comprising amphiphilic azobenzene polymers, chitosan and pluronic F127

AbstractThis study investigates the reinforcement of pluronic (PF127) based temperature responsive hydrogels with photosensitive functionalities to create smart and injectable materials. For this purpose, 4‐[4‐[(4‐phenyl)azo]phenoxy] methacrylate (PAzPMA) was synthesized and further polymerized via reversible addition‐fragmentation chain transfer (RAFT) polymerization. The structures of the copolymers were characterized by several techniques such as Fourier‐transform infrared (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The azobenzene‐functionalized copolymer was combined with P127 solid polymer in micelle form and with P127 micelles in solid form to obtain PF127‐AzoMx and PF127‐AzoPx gels, respectively. When the temperature profiles of the PF127‐AzoMx and PF127‐AzoPx systems were compared with PF127, sol–gel phase transition were shifted to lower temperatures due to stronger hydrophobic interactions. Additionally, different concentrations of N,N,N‐trimethyl chitosan (f‐chitosan) were added to the gel systems and their rheological properties were investigated by exposing them to UV light. It has been observed that the presence and concentration of f‐chitosan are important for the variation of the interactions' strength between the micelles. The study highlights the potential of multifunctional hydrogels for specific biomedical applications that combine sensitivity to both thermal and optical stimuli for controlled drug delivery and tissue engineering purposes.

Changes in Hip Isometric Strength of Female College Soccer Players After High-Workload Training Session.

The hip adductor and abductor muscles play vital roles as stabilizers in the lower-extremity. Their activation during soccer-specific actions is essential, but local muscular fatigue can hinder athletic performance and increase the risk of injury. This study aimed to observe the variations in frontal plane hip strength in female college soccer players before and after ahigh-workload soccer-specific training session. Furthermore, the study sought to compare the relative changes in hip strength with the internal and external load measures obtained during that session. Twenty female college soccer players participated in a retrospective observational study. Isometric hip adductor and abductor strength were measured before and after a training session in the college spring season. Measurements were taken with a handheld dynamometer (MicroFET 2) while the players were supine. Global positioning system sensors (Catapult Vector S7), commonly worn by players during training sessions and competitive matches, were used to measure external and internal loads. Statistical analyses were performed using paired samples t test to assess hip adductor and abductor strength changes before and after the training session. Spearman rank was used to identify correlation coefficients between global positioning system data and isometric hip strength. The findings revealed significant decreases in the strength of the right hip adduction (P = .012, -7% relative change), right abduction (P = .009, -7.6% relative change), and left abduction (P = .016, -4.9% relative change) after the training session. Furthermore, relative decreases in hip isometric adduction and abduction strength are related to the distance covered at high speeds. The results of this study highlight that hip isometric adduction and abduction strength tend to decrease after exposure to high workloads during soccer-specific training.

Heavy aggregate and different admixtures efffect on parquets: chrome, magnetite, and quartz-based surface hardener

This paper presents the mechanical and micro-structure results of concrete parquet blocks. The blocks were generated by utilizing the same part in the bottom part and by substituting different proportions (40%, 30%, 20%, and 10%) of heavy aggregate like chromite aggregate, magnetite aggregate, normal aggregate, and surface hardener in the upper part. The parquet sample tests were conducted on TS 2824 EN 1338. The test outcomes indicated that utilizing diverse aggregate and chemical materials boosted the abrasion resistance, 40% magnetite and quartz-based concrete parquet block samples demonstrated the best abrasion resistance values. Also, the minimum amount of mass loss was discovered in the samples that possess high water absorption at the freezing-thaw test. The different material substitutions in the sheet of the surface of the concrete parquet block samples altered the tensile strength of the samples, even though they did not bring about an outstanding variation in the compressive strength of the concrete parquet samples.

Assessment of the Mechanical Properties of Different Suture Materials for Oral Surgery: An In Vitro Tensile Strength Study.

Sutures are essential components of wound closure in oral surgery, and the mechanical properties of suture materials play a crucial role in determining surgical outcomes. Understanding the tensile strengths of various suture materials is vital for selecting the most appropriate material for specific clinical applications. This study aimed to assess the tensile strength of suture materials commonly used in oral surgery through an in vitro tensile strength study. A total of 192 samples of six commonly used suture materials (polyglycolic acid (PGA), polyglactin 910 (PGLA), polylactic acid (PLA), polydioxanone (PDO), silk, and nylon) were subjected to tensile strength testing using a universal testing machine. Descriptive statistics were used to summarize the tensile strength of each suture material. A comparative analysis was conducted using appropriate statistical tests to identify any significant differences in the tensile strength among the different materials. Significant variability in tensile strength was observed among the suture materials in newtons (N). PGLA exhibited the highest mean tensile strength (38.7 N), followed closely by PDO (37.1 N), whereas silk displayed the lowest tensile strength (32.8 N). Comparative analysis revealed significant differences in the tensile strength among the materials (p < 0.001). This study provides valuable insights into the mechanical properties of the suture materials commonly used in oral surgery. These findings underscore the importance of considering tensile strength when selecting suture materials for specific clinical scenarios, thereby optimizing wound closure techniques and improving patient outcomes.

Subduction Zone Geometry Modulates the Megathrust Earthquake Cycle: Magnitude, Recurrence, and Variability

AbstractMegathrust geometric properties exhibit some of the strongest correlations with maximum earthquake magnitude in global surveys of large subduction zone earthquakes, but the mechanisms through which fault geometry influences subduction earthquake cycle dynamics remain unresolved. Here, we develop 39 models of sequences of earthquakes and aseismic slip (SEAS) on variably‐dipping planar and variably‐curved nonplanar megathrusts using the volumetric, high‐order accurate code tandem to account for fault curvature. We vary the dip, downdip curvature and width of the seismogenic zone to examine how slab geometry mechanically influences megathrust seismic cycles, including the size, variability, and interevent timing of earthquakes. Dip and curvature control characteristic slip styles primarily through their influence on seismogenic zone width: wider seismogenic zones allow shallowly‐dipping megathrusts to host larger earthquakes than steeply‐dipping ones. Under elevated pore pressure and less strongly velocity‐weakening friction, all modeled fault geometries host uniform periodic ruptures. In contrast, shallowly‐dipping and sharply‐curved megathrusts host multi‐period supercycles of slow‐to‐fast, small‐to‐large slip events under higher effective stresses and more strongly velocity‐weakening friction. We discuss how subduction zones' maximum earthquake magnitudes may be primarily controlled by the dip and dimensions of the seismogenic zone, while second‐order effects from structurally‐derived mechanical heterogeneity modulate the recurrence frequency and timing of these events. Our results suggest that enhanced co‐ and interseismic strength and stress variability along the megathrust, such as induced near areas of high or heterogeneous fault curvature, limits how frequently large ruptures occur and may explain curved faults' tendency to host more frequent, smaller earthquakes than flat faults.

Investigation of electromagnetic fluctuations in a magnetically screened high beta plasma

We report low-frequency electromagnetic turbulence in large-volume plasma devices in a region that receives magnetically screened plasma. The magnetic screen is produced by the activation of a large solenoid that generates a strong magnetic field ( BEEF ) transverse to the background axial magnetic field ( Bz ). The magnetic field strength variation in BEEF controls the plasma diffusion and is responsible for parametric profile modifications in large volume plasma devices. The turbulence is characterized by the observed features of an electromagnetic mode having frequency ordering in the lower hybrid range (f ci < f < f LH). The free energy source for the excited turbulence is believed to be the prevalent finite radial pressure gradient in the system. The excited electromagnetic mode shows typical scales for the wave number, k⊥ ∼ 0.13 cm−1 and frequency f ∼ 6 kHz and propagates with phase velocity comparable to ion acoustic velocity, C s in electron diamagnetic drift direction. It is believed that the low-frequency pressure gradient-driven electromagnetic mode exhibits coupling with the lower hybrid or whistler wave.

Metal accretion scars may be common on magnetic, polluted white dwarfs

More than 30% of white dwarfs exhibit atmospheric metals, which are understood to be from recent or ongoing accretion of circumstellar debris. In cool white dwarfs, surface motions should rapidly homogenise photospheric abundances, and the accreted heavy elements should diffuse inward on a timescale much longer than that for surface mixing. The recent discovery of a metal scar on WD 0816–310 implies its B ≈ 140 kG magnetic field has impeded surface mixing of metals near the visible magnetic pole. Here, we report the discovery of a second magnetic, metal-polluted white dwarf, WD 2138–332, which exhibits periodic variability in longitudinal field, metal line strength, and broadband photometry. All three variable quantities have the same period, and show remarkable correlations: the published light curves have a brightness minimum exactly when the longitudinal field and line strength have a maximum, and a maximum when the longitudinal field and line strength have a minimum. The simplest interpretation of the line strength variability is that there is an enhanced metal concentration around one pole of the magnetic field; however, the variable line-blanketing cannot account for the observed multi-band light curves. More theoretical work is required to understand the efficiency of horizontal mixing of the accreted metal atoms, and the origin of photometric variability. Because both magnetic, metal-polluted white dwarfs that have been monitored to date show that metal line strengths vary in phase with the longitudinal field, we suggest that metal scars around magnetic poles may be a common feature of metal-polluted white dwarfs.

A practical process for effective thickening of silica shells formed onto spherical cores by considering the variation in ionic strength during sol-gel reaction

A novel process for coating spherical silica cores with a thick, mesoporous shell to obtain core-shell type mesoporous silica particles (C-MSPs) was developed. The solution pH during the sol-gel reaction in the presence of cetyltrimethylammonium bromide (CTAB), which was used for micelle templates, was measured to model the concentrations of ionic species. Silicate ions were of particular interest because their concentration rapidly increased by the hydrolysis of tetraethyl orthosilicate (TEOS) at high concentrations. The silicate ions present in the reaction mixture were determined by rate equations for the hydrolysis of TEOS and the condensation of silica. Estimating the ionic strength based on the modeled concentrations of ionic species in the solution allowed us to design an appropriate process of coating particles with a mesoporous silica shell. Mesoporous shells were effectively thickened by the continuous addition of TEOS at controlled feeding rates, where the concentration of silicate ions was kept lower than the solubility of silica, which helped suppressing the generation of secondary particles (by-products). Micron-sized C-MSPs with a mesoporous shell around a submicron-sized silica core were successfully obtained by the co-addition of TEOS and CTAB. An approximately 400 nm thick mesoporous shell with a porosity similar to that of conventional thin shells was formed onto 460 nm spherical cores. The concept of controlling the ionic strength of the reaction solution can also be applied to other cores, which offers a practical approach to synthesize core-shell type mesoporous particles required in various future applications.

Unveiling the Hidden Networks: AFM Insights into Pre‐Vulcanized Hevea Latex and Its Profound Impact on Latex Film Mechanical Properties

AbstractNatural rubber (NR) films with different natural networks—concentrated NR (CNR), deproteinized NR (DPNR), and small rubber particles (SRP)—are investigated to explore the relationship between network structure and film properties using atomic force microscopy (AFM) in PeakForce Quantitative Nanomechanics (QNM) mode. Nitrogen content, gel content, and particle size distribution analyses reveal distinct network topologies in each latex type. Mechanical testing shows variations in tensile strength and crosslink density. AFM analysis provides insights into the crosslink network structures within the pre‐vulcanized latex film. It is found that DPNR and CNR films have a uniform distribution of crosslink networks, with DPNR exhibiting higher Young's modulus values. In contrast, SRP shows varying Young's modulus values, suggesting poor coalescence arising from a harder particle surface and a softer rubber core in an inhomogeneous network structure intrinsic to the non‐rubber components (NRCs) make‐up of SRP latex. This study highlights the pivotal role of natural network structures formed by NRCs in determining the ultimate properties of latex films, which has significant implications for the rubber industry, particularly in the production of latex‐dipped products, medical devices, and bioengineering applications.

Enhancing the mechanical properties of CF-reinforced epoxy composites through chemically surface modification of carbon fibers via novel two-step approach by addition of epichlorohydrin

The chemical surface modification was carried out in this study to improve the interface connection between carbon fiber (CF) and epoxy matrix to study the mechanical and fracture behavior of CF-reinforced epoxy composites. Finite element analysis was carried out by using ABAQUS software to simulate the variation of the tensile strength (TS), interfacial shear strength (IFSS), and interlaminar shear strength (ILSS). The chemical surface modification was carried out by the chemical oxidation by nitric acid and subsequently, addition of monomer resin of epichlorohydrin in a solution at 80 °C. The Raman spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy were carried out to ensure the successful surface modification of CFs. Subsequently, surface-modified CF-reinforced epoxy composites were prepared through the hand lay-up method with the volume fraction of 20 wt.%, and curing was carried out at 80 °C for 4 h. The TS, IFSS, and ILSS values equaled 462.82 MPa, 156 MPa, and 4.1 MPa for modified CF/epoxy composites were achieved, respectively, which are improved remarkably compared to unmodified ones (380, 81, and 2.9 MPa). These improvements are attributed to the successful surface modification of CFs by epichlorohydrin. The surface modification causes the increase in wettability of CFs and the formation of mechanical interlocking and interaction between CFs and epoxy matrix was achieved through uniform and homogenous distribution of epichlorohydrin on the surface of CFs. Fractography was carried out, which indicated the sound and uniform adhesion between CF and epoxy matrix. Achieved results are consistent with simulated results.

Electrical Capacitors Based on Silicone Oil and Iron Oxide Microfibers: Effects of the Magnetic Field on the Electrical Susceptance and Conductance.

This paper presents the fabrication and characterization of plane capacitors utilizing magnetodielectric materials composed of magnetizable microfibers dispersed within a silicone oil matrix. The microfibers, with a mean diameter of about 0.94 μm, comprise hematite (α-Fe2O3), maghemite (γ-Fe2O3), and magnetite (Fe3O4). This study investigates the electrical behavior of these capacitors under the influence of an external magnetic field superimposed on a medium-frequency alternating electric field, across four distinct volume concentrations of microfibers. Electrical capacitance and resistance measurements were conducted every second over a 60-s interval, revealing significant dependencies on both the quantity of magnetizable phase and the applied magnetic flux density. Furthermore, the temporal stability of the capacitors' characteristics is demonstrated. The obtained data are analyzed to determine the electrical conductance and susceptance of the capacitors, elucidating their sensitivity to variations in microfiber concentration and magnetic field strength. To provide theoretical insight into the observed phenomena, a model based on dipolar approximations is proposed. This model effectively explains the underlying physical mechanisms governing the electrical properties of the capacitors. These findings offer valuable insights into the design and optimization of magnetodielectric-based capacitors for diverse applications in microelectronics and sensor technologies.