Cross-sectional Morphology Research Articles

The effects of orientation angle of bamboo strands on the properties of bamboo oriented strand board

Bamboo oriented strand boards (BOSBs) with orientation angles of bamboo strand ranging from 0° to 90°, with increments of 15° were fabricated in this study at first. The effect of orientation angles on the physical and mechanical properties of the boards in the terms of the thickness swelling (TS), static bending performance, and internal bond (IB) were then comprehesively evaluated. Simultaneously, the cross-sectional morphology, porosity, and internal three-dimensional structure of the boards were investigated further via a super depth-of-field digital microscope, mercury intrusion porosimetry (MIP), and Micro-Computed Tomography (Micro-CT), to elucidate the underlying influence mechanisms of strand orientation angle on board performance. Results demonstrated that the orientation angle of bamboo strands significantly impacts the performance of BOSBs. When the orientation angle of bamboo strands ranged from 0° to 45°, the structure of the BOSB was relatively loose, with porosity increasing as the orientation angle increased. The highest porosity was observed at a 45° orientation angle. However, when the orientation angle exceeded 45°, the inter-layer and intra-layer bamboo strands gradually formed an effective interlocking structure, leading to a decrease in porosity with increasing orientation angle. This interlocking phenomenon was a crucial factor contributing to the improved mechanical properties of the board. The optimal orientation angle range was found to be between 60° and 75°, where the overall board performance met the requirements for heavy-duty BOSBs under humid conditions.

Mechanism, microstructure and performance of novel electron beam freeform fabrication compared with conventional method

This paper proposes a new method: the pre-melting electron beam freeform fabrication method. This new method aims to mitigate the excessive heat input associated with directly forming a molten pool on the deposit and the poor formation caused by severe agitation of the molten pool. Consequently, it seeks to refine the internal microstructure of the part and enhance its mechanical properties. Using TC4 alloy as the research subject, this study performs a comparative analysis between the EBF and PEBF methods in terms of structural composition, deposit formation, cross-sectional morphology, microstructure, tensile strength, fracture path, and grain size. The research findings indicate that the PEBF method, due to its significantly lower heat input, results in the maximum α phase width being reduced to 1/4 to 1/5 of that observed with the EBF method. This reduction in α phase width leads to an increase in the tensile strength of the deposit from 784 to 840 MPa and an enhancement in the fracture strain from 0.22 to 0.34, which is close to the strength difference (68 MPa) calculated for the two methods using the Hall-Petch equation. The comparative results underscore the superiority of the PEBF method, demonstrating its potential to improve mechanical properties.

Influence of the dual-current method on the properties and growth mechanisms of micro-arc oxidation coatings

Although the micro-arc oxidation (MAO) technique can significantly enhance metal properties, the numerous variables involved in the preparation of MAO coatings lead to inconsistent properties. This study prepared MAO coatings using both single-current and dual-current methods with varied current parameters. The effects of these methods on the coating properties were investigated. Scanning electron microscopy (SEM) was used to analyze the microscopic and cross-sectional morphologies of the coatings prepared using both methods. Subsequently, the physical phase composition of the coatings was analyzed using X-ray diffraction (XRD). Finally, the coatings' tribological and corrosion resistance properties were evaluated through tribological and electrochemical tests. The results demonstrate that coatings prepared using the decreased-current method in dual-current mode exhibit outstanding abrasion and corrosion resistance. Moreover, the mechanism of action of the method is proposed, which provides a new idea and method to enhance the performance of MAO coatings in a simple and efficient way.

Effect of heat treatment on the interfacial element diffusion and hardness of FeCoNiCrAl high-entropy alloy coatings

FeCoNiCrAl high-entropy alloy (HEA) coatings have here been prepared on Q235 steel by using the plasma spraying technology. The effects of heat treatment (300 °C, 400 °C, and 500 °C) on the coating phase, surface and cross section morphologies, surface Brinell hardness (HRB), cross section Vickers hardness (HV), and element diffusion at the coating interface, were then investigated. The distribution of pores, cracks, and unmelted particles on the surface of the coating was analyzed by scanning electron microscopy (SEM). The results showed that the BCC crystalline structure of the HEA coating did not change significantly after heat treatment at 300 °C, 400 °C, and 500 °C. In addition, the bonding between the coating and the matrix interface became significantly improved, and the cracks at the coating interface were eliminated. New oxides that filled the pores and cracks inside and at the interface of the coating were also observed as the temperature and holding time increased. Furthermore, the surface hardness of the Q235 steel was reduced as a result of the spray coating. However, this surface hardness was increased to HRB 85 (or even more) after heat treatment. Compared with the other samples, the coating sample that was heat-treated at 500 °C showed the best strength.

Susceptibility-induced internal gradients reveal axon morphology and cause anisotropic effects in the diffusion-weighted MRI signal

Diffusion-weighted MRI is our most promising method for estimating microscopic tissue morphology in vivo. The signal acquisition is based on scanner-generated external magnetic gradients. However, it will also be affected by susceptibility-induced internal magnetic gradients caused by interactions between the tissue and the static magnetic field of the scanner. With 3D in silico experiments, we show how internal gradients cause morphology-, compartment-, and orientation-dependence of spin-echo and pulsed-gradient spin-echo experiments in myelinated axons. These effects surpass those observed with previous 2D modelling corresponding to straight cylinders. For an ex vivo monkey brain, we observe the orientation-dependence generated only when including non-circular cross-sections in the in silico morphological configurations, and find orientation-dependent deviation of up to 17% for diffusion tensor metrics. Interestingly, we find that the orientation-dependence not only biases the signal across different brain regions, but also carries a sensitivity to the morphology of axonal cross-sections which is not attainable by the idealised theoretical diffusion-weighted MRI signal.

Field shaper-based solutions to the bulging problem in magnetic pulse spot welding of dissimilar metal plates

Magnetic pulse spot welding based on a field shaper can effectively achieve spot welding of dissimilar metal plates by using the multi-turn flat coil and magnetic gathering through the field shaper. Through existing experimental research, it has been found that when using this method for welding, there will be a serious bulging problem in the center of the welding area, which will affect the flatness and aesthetics of the welding area, thereby affecting its application range. To solve this problem, this work proposes two different welding methods for welding dissimilar AA1060 aluminum and SS304 steel plates with a thickness of 1 mm: one based on the center opening of the flying plate and the other based on the pre-deformation of the flying plate. The causes of bulging and the effects of discharge voltage, welding gap, and inner hole radius of the field shaper on bulging size were studied. The cross-sectional morphology and mechanical properties of welded joints obtained by two welding methods were studied through numerical simulation, cross-sectional analysis, and tensile testing. The results indicated that both welding methods can successfully eliminate the bulging problem, and the point welding method based on the center opening of the aluminum plate can also reduce the minimum welding energy required for effective welding and improve welding efficiency. In addition, microscopic analysis results showed that a waveform composite interface was formed at the welding interface of the joint, and the connection performance of the welded joint was good. These two welding methods can also be extended to the welding of other dissimilar metal plates, which is of great significance for the industrial application of magnetic pulse spot welding technology based on field shaper.

Incorporating Mixed-Ligand Zeolitic Imidazolate Framework into Polydimethyldiethoxysilane (PDMDES) Membrane for Enhancing Alcohol Pervaporation Recovery.

In the present study, a zeolitic imidazolate framework with mixed ligands, ZIF-8-90, was synthesized and embedded into an ultrathin polydimethyldiethoxysilane (PDMDES) matrix to prepare a ZIF-8-90/PDMDES mixed matrix membrane (MMM) for the enhanced recovery of alcohols from dilute aqueous solutions via pervaporation, using a facile solution coating method. The synthesized ZIF-8-90 particles demonstrated superior hydrophobicity and thermal stability compared to those of both ZIF-8 and ZIF-90 particles. Furthermore, the hydrophobicity, thermal stability, and sorption ability for alcohols of the ZIF-8-90/PDMDES MMM were significantly improved, attributed to the incorporation of mixed-ligand ZIF-8-90. Notably, the MMMs displayed two distinct cross-sectional morphologies: (1) ZIF-8-90 particles enveloped by PDMDES polymer forming filler bulges and (2) an accumulation of ZIF-8-90 particles resembling a brick-wall-like structure. The MMM incorporating 2.5 wt % ZIF-8-90 exhibited the optimal performance among the fabricated MMMs with various ZIF-8-90 loadings, spanning from 0 to 3.2 wt %. The effects of feed concentrations and operation temperatures were systematically investigated. The best pervaporation performance was achieved using the 2.5 wt % ZIF-8-90-filled MMM, effectively separating a 5.0 wt % ethanol/water mixture at 60 °C, yielding a distinguished total flux of 7.70 kg·m-2·h-1, an improved separation factor of 9.96, and an extraordinarily high PSI of 68.99 kg·m-2·h-1. Comparative analyses highlighted the superior pervaporation performance of the ZIF-8-90/PDMDES MMM over ZIF-8/PDMDES MMM, ZIF-90/PDMDES MMM, and other MMMs, underscoring its potential for practical applications in alcohol recovery.

Regulation of protonation in aramid nanofiber films for improved mechanical properties

Abstract Aramid nanofibers (ANFs) are a strong and heat resistant nanomaterial that can be isolated from commercial poly(p-phenylene terephthalamide) (PPTA) fibers. These nanofibers allow bottom-up self-assembly to form macroscale structures in various form factors through a simple reprotonation process. However, the mechanical properties of these reassembled ANF structures often fall short of those of PPTA fibers, mainly due to insufficient packing, non-uniform microstructures, and low crystallinity. In this study, we present ANF films with improved mechanical properties prepared by a repeated spin-coating technique combined with a reprotonation process using deionized water and formic acid at concentrations ranging from 20 to 60 wt.%. Extensive analyses were performed on the resulting ANF films to evaluate their surface and cross-sectional morphologies, chemical bonds and compositions, thermal stabilities, and mechanical properties. The fabricated ANF films exhibited remarkable performance, with an elastic modulus of 6.7 GPa, tensile strength of 680 MPa, and toughness of 7.7 MJ m−3, while maintaining the inherent thermal stability of PPTA fibers. These properties significantly exceed those of previously reported ANF films, broadening the potential applications for ANF films in various fields.

Investigation of formation, microstructure and hardness of Ti-6Al-4V single tracks via Joule-fused filament additive manufacturing

Purpose This paper aims to investigate a novel additive manufacturing (AM) method for titanium alloy using Joule heat as the single heat source to melt TC4 wire, which intends to provide a new low-power, low-cost solution for the processing of titanium alloys. Design/methodology/approach When current flows through the wire and the substrate, Joule heat will be generated to melt the wire and join the wire with the substrate. By stacking the wire layer by layer, finally a part can be formed. The cross-sectional morphology, microstructure and hardness of TC4 single track deposits formed by Joule heat melting wire AM were investigated by various characterization methods. Findings The melting width and melting penetration decreased with the increase of printing speeds. There is no obvious change in single track morphology with the change of printing pressures. The melting width and melting penetration increased with the increase of printing currents. The observation of the internal microstructure of a single track reveals a decrease in grain size as printing speeds increase. The average hardness of the single track was about 363 HV, which is comparable to the hardness of the parts fabricated by selective laser melting process. The printing power is less than 300 W, which is lower than other AM processes. Originality/value This paper provides a novel solution for the processing of titanium alloy parts. Compared with other expensive energy sources, this work only uses an ordinary DC power supply as the energy source. The printing process is simple and the cost is low. The power is much lower than other AM processes.

Tool–Branch Interaction Mechanism of Impact-Pruning Process Based on Finite Element Method

This study addresses the necessity for a more profound comprehension of the mechanical behavior and fracture mechanisms of tree branches during impact pruning. The methodologies of the research are to develop a failure model of impact-cutting mechanics and a tool–branch interaction model using the finite element method (FEM). The validation of the model was conducted through the measurement of cutting forces and cross-sectional morphology in the field. A comparative analysis between experimental and simulation data revealed an average relative error below 15% for cutting force and below 10% for the cross-sectional ratio, thereby confirming the accuracy of the model. The findings indicate the presence of plastic deformation within the cutting zone, with elastic deformation prevailing in the surrounding region. As the branch approaches the yield point, the phenomenon of plastic deformation intensifies, resulting in a notable increase in internal energy demands, particularly in larger branches. The optimal pruning diameter was identified as 15 mm. An increase in cutting velocity raises the peak cutting force by 460.9 N per m/s, while a 1° increase in the blade wedge angle adds 34.9 N. A reduction in normal stress by increasing the tool back angle improves energy efficiency. This study provides insights to optimize pruning practices, enhancing efficiency and precision.

Synthesis, structure characterization, and corrosion properties of duplex electroless Ni-P/Ni-B and Ni-P/Ni-B-W coatings on mild steel

This study investigates the formation of duplex electroless Ni-P/Ni-B and Ni-P/Ni-B-W alloys through electroless plating process coatings on mild steel using hypophosphite and sodium borohydride as a reducing agent, employing heat-treated. Electroless plating is affordable and suitable for coating convoluted structures. Duplex electroless on mild steel was characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectrometry (EDS), scanning electron microscopy (SEM) were used to examine the surface and cross-sectional morphologies of the duplex coating, and finally study electrochemical corrosion properties. The analysis reveals that duplex coating yields a thicker, more homogeneous coating with a characteristic cauliflower morphology and spherical nodular structures. The coating was initially amorphous, but finally crystallized when heated to 400 °C. More corrosion resistance was found in the Ni-P/Ni-B and Ni-P/Ni-B-W layers when Ni-B served as the outer covering. This study focuses on the important effects of varying tungsten concentrations and heat treatment on the corrosion resistance, surface quality, and microstructural characteristics of duplex coatings. Showed improved corrosion resistance when exposed to 0.5 g/L of Na2WO4.

Development and distribution of submarine channels associated with sediment gravity flows in the modern Huanghe (Yellow River) subaqueous delta

BackgroundGravity-driven depositional processes play a pivotal role in shaping the geomorphology of subaqueous deltas worldwide, particularly by eroding the seafloor, leading to the formation of rugged submarine channels (SCs) and triggering various subaqueous geohazards. A comprehensive understanding of SCs is crucial for elucidating these depositional mechanisms and mitigating the risks associated with submarine geohazards. Although SCs in the Huanghe delta front have been previously identified, often described as seafloor gullies or subsurface “disturbed strata,” most studies have primarily concentrated on their engineering geological properties. However, there has been limited research on the scale, morphology, and development of these SCs, especially those that are buried within the stratigraphy.MethodsThis study integrates high-resolution sub-bottom data, sediment core analyses, and historical bathymetric data to investigate the morphology, distribution, and formation mechanisms of SCs in the Huanghe subaqueous delta.ResultsThe SCs, both buried and exposed, are widespread along the middle and upper delta front, predominantly located at or near the landward flank of sediment gravity flow (SGF) -related accumulations. The buried SCs are characterized by cut-and-fill structures with transparent to semi-transparent fills, indicating rapid infilling processes as SGF energy dissipates. These buried channels were preserved within different sets of delta front deposits formed during 1855–1964 CE, 1964–1976 CE, and 1976–2007 CE, with the latter two periods separated by a significant lobe-switching event in 1976 CE. This event, combined with prevailing southeastward sediment transport and erosional regimes, appears to have controlled the preservation of SCs along the delta front: SCs in the Diaokou Lobe's delta front (pre-1976) suffered significant erosion, leaving only one set of channel (erosional remnants) preserved, while the SCs in the Qingshuigou Lobe's delta front (post-1976) are characterized by well-preserved, multi-phase channels at different horizons. The cross-section morphology of the SCs reveal three primary types: symmetrical, asymmetrical, and composite, corresponding respectively to (1) idealized SGF incision, (2) uneven incision intensity on either side of the SCs, and (3) the merging of two or more symmetrical/asymmetrical SCs.ConclusionsWe describe in detail the morphology, distribution and development of SCs in the modern Huanghe subaqueous delta. These findings provide insights into the formation and distribution of SCs in other shallow marine settings, particularly in delta front areas, and potentially offer information for disaster prevention and engineering development in such regions.

Effect of voltage and time on microstructure and corrosion resistance of anodic oxidation film on Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy

Anodic aluminum oxide (AAO) films were prepared on the surface of Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy in a 160 g/L H2SO4 electrolyte. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), immersion weight loss, and electrochemical testing were used to analyze the element and phase composition, surface and cross-section morphology and corrosion resistance of AAO films in NaCl solution. The effects of anodic oxidation voltage and time on the microstructure and corrosion resistance of AAO films were discussed. The results show that the AAO film on the surface of Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy was mainly composed of Al2O3, with a dense barrier layer near the aluminum matrix and a porous layer on the outer layer. With the increase of anodic oxidation voltage and oxidation time, the thickness and pore diameter of AAO film increases gradually, and the corrosion resistance increases gradually. After anodizing for 15V-60min, the thickness of AAO film on the surface of Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy reached 45.51μm, the corrosion current density decreased to 0.79 µA/cm2, and the weight loss decreased to 0.19 µg·cm−2·h−1, showing the best corrosion resistance. This study provides a new method to improve the corrosion resistance of Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy used in the Marine environment and discusses the corrosion behavior of Al-5.5Zn-0.03In-1Mg-0.03Ti-0.08Sn alloy with AAO films in the Marine environment.

Effect of bath temperature on corrosion resistance of electroless Ni-P coating on 5A90 Al-Li alloy

Abstract The Al-Li alloy exhibits outstanding characteristics, including remarkable specific strength, elevated specific stiffness, and heightened susceptibility to localized corrosion. Electroless Ni-P coating is extensively applied over the appearance of aluminum alloys to enhance their corrosion resistance. Electroless Ni-P coating was applied to 5A90 Al-Li alloy at various plating temperatures for the study presented in this publication. The coating’s surface, composition, and cross-sectional morphology were examined using SEM/EDS. The corrosion behavior of coating was studied using the potentiodynamic polarization curve. Results showed that coating on the surface of 5A90 Al-Li alloy was uniform and smooth. Ni and P elements were evenly distributed in the coating. The thickness of coatings at 80°C, 85°C, 90°C and 95°C was about 3.98 μm, 5.5 μm, 11.2 μm, and 10.29 μm, respectively. As the temperature of the bath increased, the corrosion resistance of the coating first increased and afterward decreased. The corrosion resistance of the coating might be correlated with its thickness.

The cross-sectional morphology of the proximal femoral diaphysis is defined by the anteversion angle.

Osteoporosis in postmenopausal women is one of the causes of femoral fractures and is prevented by the administration of bisphosphonates. Individual morphologies are considered to increase the risk of atypical fractures associated with long-term administration. To evaluate cortical bone morphology quantitatively, we established a method to measure the distance from the center point of a cross-section to the external and internal borders based on CT images. Using this method, 44 sides of a female femoral skeleton specimen were examined and areas of protrusion and thickening in the medial anterior and lateral posterior regions just below the lesser trochanter were identified. These positions strongly correlated with the anteversion angle, suggesting the involvement of the distribution of the load received from body weight defined by the angle. The finite element method was used to examine the relationships between the positions of these areas with compressive and tensile stress distribution areas in the one-legged standing condition. The medial anterior region and lateral posterior region protruded and thickened in response to compressive and tensile stress, respectively. In addition, a hierarchical relationship was observed between the anteversion angle, tensile stress distribution, protrusion, and thickening in femurs with thinning of cortical bone, indicating that morphogenesis occurs adaptively to loading. The present results demonstrate the usefulness of this method in considering the formation mechanism and function of the femoral diaphysis and suggest that bone remodeling is necessary to maintain adaptability.

Influence of laser remelting on the microstructure and properties of Mo2FeB2 ternary boride coatings prepared by laser cladding

This study investigated the impact of laser remelting on the microstructure and properties of Mo₂FeB₂ coatings on AISI 1045 steel substrate. Different laser remelting powers were applied to pre-deposited Mo₂FeB₂ coatings. The cross-sectional morphology, phase composition, microstructure, microhardness, residual stress, fracture toughness, and wear resistance of the coatings were systematically analyzed. Compared to the untreated coatings, the remelted coatings exhibited reduced height and significantly refined microstructure. The primary phase observed in the coating was Mo₂FeB₂, accompanied with minor phases such as Cr₃C₂. Optimal microhardness (1209.4 HV0.5), fracture toughness (14.5 MPa·m1/2), and wear rate (5.4× 10−5 mm3/N·m) were achieved at a remelt power of 1200 W. Additionally, the residual stress in the coatings decreased with increasing power, reaching a minimum of 268 MPa at 1500 W. The wear mechanism transitioned from adhesive wear to abrasive wear with increasing remelting power. These findings highlight the beneficial effects of laser remelting in enhancing the performance of Mo₂FeB₂ coatings for industrial applications.

Study of the Synergistic Influence of Plasma Electrolytic Oxidation and Wet Post-Treatment on the Surface of AA7075.

In this study, we enhanced the corrosion and microbial resistance of aluminum 7075 alloys by applying a thin layer of alumina through plasma electrolytic oxidation (PEO) in an alkali-silicate electrolyte. In addition, the influence of film sealing on coated aluminum alloy 7075 was studied in detail, specifically in oil and water at 100 °C after treatment. The surface and cross-sectional morphology, element composition, and phase composition of the PEO coatings were characterized by using scanning electron microscopy (SEM) assisted with energy-dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD), respectively. The corrosion resistance of the coating on AA7075 PEO was evaluated before and after post-treatment using hot water and hump oil at 100 °C. This assessment was conducted by using various electrochemical techniques, including open-circuit potential (OCP), linear polarization resistance (LPR), potentiodynamic polarization scan (PD), electrochemical impedance spectroscopy (EIS), and cyclic potentiodynamic scan (CPS). The results showed that the corrosion resistance of the AA7075 alloy was significantly improved after the PEO coating. The AA7075 + SF, among all of the examined alloys, exhibited superior corrosion properties, due to its fat sealing. This is probably due to the formation of a mixed fatty acid layer from oil on the surface of the AA7075 PEO, which synthesizes a hydrophobic layer. Interestingly, the samples treated with PEO showed a great resistance to microbial growth.

Magnetic resonance neurography in the diagnosis of neurological subtypes of thoracic outlet syndrome.

Neurological thoracic outlet syndrome (TOS) can be challenging to diagnose, particularly given its described subtypes of neurogenic TOS (NTOS) and disputed TOS (DTOS) that exhibit variable clinical presentations and etiologies. The diagnostic workup of TOS often includes magnetic resonance neurography (MRN) of the brachial plexus. Specific MRN imaging modifications for TOS evaluation are required to maximize spatial and contrast resolution to increase the conspicuity of nerve segments and their relationships to surrounding osseous structures. Dynamic assessment with arm positioning is used to evaluate outlet narrowing and compression of the plexus. Individual nerve segments are interrogated for their longitudinal and cross-sectional morphologies and signal characteristics. In patients with NTOS, MRN may reveal focal impingement of the C8/T1 nerve roots and/or lower trunk with accompanying abnormal T2-weighted signal hyperintensity. Predisposing anatomical entities include cervical ribs, rib synostoses, hypertrophic callous following clavicular fracture, remnant first thoracic rib from prior incomplete resection, and variable perineural scarring. In comparison, DTOS patients frequently demonstrate signal hyperintensity and enlargement of the mid plexus (trunk and division level), with narrowing of the costoclavicular interval. Following comprehensive diagnostic workup that frequently includes electrodiagnostic testing, patients are directed to different management pathways. Nonsurgical management is considered for all cases of DTOS; all patients with NTOS or DTOS who fail conservative treatment warrant referral for a surgical opinion. If surgery is pursued, MRN can be helpful in preoperative planning.

Three-dimensional assessment of the nasopharyngeal airway in Down syndrome during the mixed dentition period: a case-control study.

In this retrospective case-control study, we aimed to evaluate the nasopharyngeal airway volume of children with Down syndrome (DS) and compare the results with those of control participants well matched for sex and age. Fifteen children with DS (mean age = 9.43 ± 0.38 years; 8 boys, 7 girls) and 15 control participants (mean age = 9.51 ± 0.40 years; 8 boys, 7 girls) were enrolled. The nasopharyngeal airway volume and the cross-sectional morphology were measured with cone-beam computed tomography taken for orthodontic treatment. All measurements were assessed by analysis of covariance (ANCOVA) using Bonferroni post hoc pairwise comparison tests. Covariates were body height and body weight, and the ANB angle and the mandibular plane angle. Significance was set at P < .0019. Nasal airway, superior airway, and total airway volumes of DS participants were significantly smaller than those of the control participants in ANCOVA results adjusted for ANB angle and mandibular plane angle (P = .000). In ANCOVA results adjusted for body height and body weight, no statistically significant differences in the volume measurements were found. The results indicate that the nasopharyngeal airway volume differs between children with and without DS and that the airway volume tends to be smaller in DS children than in children without DS.

Enhancing mechanical and thermal properties of polyvinyl alcohol/curdlan composite hydrogels and aerogels via freeze-casting technique

This study introduces a novel approach to fabricating polyvinyl alcohol (PVA)/curdlan (CURD) composite aerogels by employing the freeze-casting technique to achieve exceptional mechanical and thermal properties. Our research demonstrated that the formation of dual-network structure that combines the mechanical strength of PVA with the thermal stability of CURD. Scanning electron microscopy revealed a unique honeycomb-like cross-sectional morphology in the PVA/CURD aerogels. Notably, the PVA/CURD composite hydrogel demonstrated consistent compressive stress performance even after 50 compression cycles and exhibited minimal swelling (only 4%) when immersed in distilled water for 24hours. Furthermore, the aerogels exhibited varying swelling ratios in different pH environments, with a significant increase observed in acidic conditions. Thermal analysis confirmed the enhanced thermal stability of the composite aerogels, attributed to the incorporation of CURD. These findings suggest that PVA/CURD composite aerogels have promising applications in fields that require materials with robust mechanical and thermal endurance.