Search Results (80)

Carbon nanotubes (MWCNTs) were synthesized in situ on para-aramid fabrics (gCPO) via a low-temperature (450 °C) chemical vapor deposition (CVD) process to enhance interfacial pull-out, frictional, and fracture toughness characteristics. FESEM analysis confirmed CNT coverage on fiber surfaces, while FTIR, Raman, and XRD results indicated limited structural modification without significant polymer degradation. The CNT-functionalized fabrics exhibited a 66.19% increase in maximum pull-out force, 55.32% improvement in interlacement rupture strength, and a three-fold rise in intra-yarn shear resistance compared with control fabrics (KPO). The static and kinetic friction coefficients increased by 26.67% and 16.67%, respectively, due to CNT-induced surface roughness, enhancing inter-fiber load transfer and reducing slippage. Single-yarn pull-out tests revealed notable gains in energy dissipation and fracture toughness (up to 1769 J/m²), whereas multi-yarn pull-out performance decreased due to excessive friction surpassing filament strength. The study demonstrates that low-temperature MWCNT growth enables effective interfacial reinforcement of soft para-aramid fabrics, establishing a novel framework for meso-scale mechanical screening of flexible nano-ballistic composites. Full article

Background/Objectives: Dental enamel constitutes the first barrier of defense against external factors that constantly generate wear and damage. This study aimed to evaluate in vitro the abrasion and roughness of dental enamel using toothpaste with and without activated charcoal and to analyze this under scanning electron microscopy (SEM). Materials and methods: The research design was experimental; 10 enamel blocks were randomly assigned to each group to perform brushing cycles with soft- and medium-filament brushes with two types of toothpaste, one with activated charcoal and one without activated charcoal. A pumice stone with etching acid was used as the positive control and artificial saliva served as the negative control; both were analyzed separately. Roughness was evaluated using a roughness meter and abrasion with an analytical balance. The surface of the enamel blocks of each group was randomly analyzed under an SEM. Statistical analysis was performed using the Shapiro–Wilk test and the homogeneity of variances with Bartlett’s test. Student’s t-test (two-tailed) was applied to compare tooth enamel roughness and abrasion. Results: Both enamel roughness (p = 0.0016) and abrasion (p = 0.0001) were significantly higher in the groups using activated charcoal paste and medium-filament brushes. SEM observation revealed greater alteration on the surface of the enamel subjected to brushing cycles with activated charcoal paste and a medium-filament brush. Conclusions: The in vitro study showed that the use of toothpaste with activated charcoal increases the roughness and abrasion of tooth enamel, especially when the medium-filament brush is used. Full article

Soft wearable actuators must align with anatomical joints, conform to limb geometry, and operate at low pneumatic pressures. Yet most twisting mechanisms rely on bulky attachment interfaces and relatively high actuation pressures, limiting practicality in assistive applications. This study introduces the first Twisting Soft Sleeve Actuator (TSSA), a self-contained, wearable actuator that produces controlled bidirectional torsion. The design integrates helically folded bellows with internal stabilization layers to suppress radial expansion and enhance torque transmission. The TSSA is fabricated from thermoplastic polyurethane using a Bowden-type fused filament fabrication (FFF) process optimized for airtightness and flexibility. Performance was characterized using a modular test platform that measured angular displacement and output force under positive pressure (up to 75 kPa) and vacuum (down to −85 kPa). A parametric study evaluated the effects of fold width, fold angle, wall thickness, and twist angle. Results demonstrate bidirectional, self-restoring torsion with clockwise rotation of approximately 30 degrees and a peak output force of about 40 N at 75 kPa, while reverse torsional motion occurred under vacuum actuation. The TSSA enables anatomically compatible, low-pressure torsion, supporting scalable, multi-degree-of-freedom sleeve systems for wearable robotics and rehabilitation. Full article

The actomyosin complex—nature’s dynamic engine composed of actin filaments and myosin motors—is emerging as a versatile tool for bio-integrated nanotechnology. This review explores the growing potential of actomyosin-powered systems in biosensing and actuation applications, highlighting their compatibility with physiological conditions, responsiveness to biochemical and physical cues and modular adaptability. We begin with a comparative overview of natural and synthetic nanomachines, positioning actomyosin as a uniquely scalable and biocompatible platform. We then discuss experimental advances in controlling actomyosin activity through ATP, calcium, heat, light and electric fields, as well as their integration into in vitro motility assays, soft robotics and neural interface systems. Emphasis is placed on longstanding efforts to harness actomyosin as a biosensing element—capable of converting chemical or environmental signals into measurable mechanical or electrical outputs that can be used to provide valuable clinical and basic science information such as functional consequences of disease-associated genetic variants in cardiovascular genes. We also highlight engineering challenges such as stability, spatial control and upscaling, and examine speculative future directions, including emotion-responsive nanodevices. By bridging cell biology and bioengineering, actomyosin-based systems offer promising avenues for real-time sensing, diagnostics and therapeutic feedback in next-generation biosensors. Full article

The integration of nanomaterials within hydrogel scaffolds offers significant promise in bone tissue engineering by improving mechanical performance and modulating cellular responses through mechanotransductive and biochemical signaling. Previous studies have demonstrated that nanodiamonds (NDs) incorporated in electrospun microfibrillar meshes enhance cellular adhesion, spreading, and cytoskeletal organization through localized mechanical reinforcement. However, the effects of ND loading into soft, bioinert three-dimensional hydrogel matrices remain underexplored. Here, we developed nanostructured 3D printing inks composed of gellan gum (GG) supplemented with a low content of ND nanoadditive (0–3% w/v). ND integration improved the shear-thinning properties of the formulation, enabling consistent filament formation and reliable extrusion-based 3D printing. Structural and mechanical assessments confirmed enhanced scaffold morphology, reduced deformation, and improved morphostructural integrity under compression and increased local stiffness at 2% ND loading (GG_ND2%). Biological assessments revealed that increasing ND content enhanced murine preosteoblast viability, proliferation, and attachment, particularly in GG_ND2%. Furthermore, bioactivation of the GG_ND2% formulation with icariin (ICA), a bioflavonoid known for its osteogenic and angiogenic activity, amplified the beneficial cellular responses of MG-63 cells to ND loading, promoting enhanced surface mineralization and improved cell–matrix interactions. Collectively, these findings highlight the potential of ND-reinforced GG scaffolds bioactivated with ICA, integrating structural reinforcement and biological functionalities that may support osteogenic responses. Full article

Soft–rigid interfaces in exoskeletons are key to balancing flexibility and structural support, providing both comfort and function. In our experience, combining Bioflex material with a rigid filament improves mechanical properties while allowing the exoskeleton to adapt to complex hand movements. Flexible components provide adaptability, reducing pressure points and discomfort during prolonged use. At the same time, rigid components provide the stability and force transfer necessary to support weakened grip strength. A key challenge in this integration is achieving a smooth transition between materials to prevent stress concentrations that can lead to material failure. Techniques for providing adhesion and mechanical locking are essential to ensure the durability and longevity of soft and rigid interfaces. One issue we have observed is that rigid filaments can restrict movement if not strategically placed, potentially leading to unnatural hand movement. On the other hand, excessive softness can reduce the force output needed for effective rehabilitation or assistance. Optimizing the interface design requires iterative testing to find the perfect balance between flexibility and mechanical support. In some prototypes, material fatigue in soft sections led to early failure, requiring reinforced hybrid structures. Addressing these issues through better material bonding and geometric optimization can significantly improve the performance and comfort of hand exoskeletons. The aim of this study was to investigate the transition between rigid and soft materials for exoskeletons. Full article

This paper catalogues a series of experiments we conducted to explore how to 3D print a DC electric motor. The individual parts of the electric motor were 3D printed but assembled by hand. First, we focused on a rotor with soft magnetic properties, for which we adopted ProtoPasta^TM, which is a commercial off-the-shelf PLA filament incorporating iron particles. Second, we focused on the stator permanent magnets, which were 3D printed through binder jetting. Third, we focused on the wire coils, for which we adopted a form of laminated object manufacture of copper wire. The chief challenge was in 3D printing the coils, because the winding density is crucial to the performance of the motor. We have demonstrated that DC electric motors can be 3D printed and assembled into a functional system. Although the performance was poor due to the wiring problem, we showed that the other 3D printing processes were consistent with high performance. Nevertheless, we demonstrated the principle of 3D printing electric motors. Full article

Direct ink writing (DIW) of low-yield-stress UV-curable silicone rubber faces challenges in maintaining dimensional accuracy due to post-extrusion swelling and viscoelastic deformation. This study proposes an ultraviolet-follow curing (UFC) method to enhance geometric precision by UV-follow curing (UFC) during deposition. The effects of UFC on filament dimensions—including width, length, cross-sectional geometry, and roundness—were systematically investigated. The mechanical properties of the printed structures were also evaluated to assess their functional integrity. The experimental results demonstrated that UFC effectively reduced extrusion swelling, achieving a filament-width deviation reduction of 22–81% and a filament-length deviation of 1.4–1.8% compared to conventional DIW. The printed rings exhibited improved roundness uniformity with reduced geometric fluctuations. Crucially, UFC enhances dimensional accuracy without compromising the mechanical performance of low-yield-stress silicones, providing a viable strategy for the high-precision additive manufacturing of soft elastomeric architectures. Full article

Resorbable microparticles can be added to hydrogel-based biocompatible scaffolds to improve their mechanical characteristics and allow localised drug delivery, which will aid in tissue repair and regeneration. It is well-known that bioprinting is important for producing scaffolds personalised to patients by loading them with their own cells and printing them with specified shapes and dimensions. The question is how the addition of such particles affects the rheological responsiveness of the hydrogels (which is critical during the printing process) as well as mechanical parameters like the elastic modulus. This study tries to answer this question using a specific system: an alginate-gelatine hydrogel containing polyhydroxybutyrate-co-hydroxyvalerate (PHBV) microparticles. Scaffolds were made by bioprinting and moulding incorporating PHBV microspheres (7–12 μm in diameter) into alginate–gelatine inks (4.5 to 9.0% w/v). The microparticles (MP) were predominantly located within the polymeric matrix at concentrations up to 10 mg MP/mL ink. Higher particle concentrations disrupted their spatial distribution. Inks pre-crosslinked with 15 mM calcium and containingMPat concentrations ranging from 0 to 10 mg/mL demonstrated rheological characteristics appropriate for bioprinting, such as solid-like behaviour (G′ = 1060–1300 Pa, G″ = 720–930 Pa), yield stresses of 320–400 Pa, and pseudoplastic behaviour (static viscosities of 4000–5600 Pa·s and ~100 Pa·s at bioprinting shear rates). Furthermore, these inks allow high printing quality, assessed through scaffold dimensions, filament widths, and printability (Pr > 0.94). The modulus of elasticity in compression (E) of the scaffolds varied according to the content of MP and the manufacturing technique, with values resembling those of soft tissues (200–600 kPa) and exhibiting a maximum reinforcement effect with 3 mg MP/mL ink (bioprinted E = 273 ± 28 kPa; moulded E = 541 ± 66 kPa). Over the course of six days, the sample’s mass and shape remained stable during degradation in simulated body fluid (SBF). Thus, the alginate–gelatine hydrogel loaded with PHBV microspheres inks shows promise for targeted drug delivery in soft tissue bioengineering applications. Full article

To reduce the hard texture of cooked early indica rice, two types of polydextrose (ST with 1% moisture content (MC) and XG with 4.7% MC) were added at 0%, 3%, 5%, 7%, and 10%, respectively, to the cooking milled rice polished from the paddies of the 2.5-year-stored IP46 variety and the newly harvested Sharuan Nian (SRN) variety. Compared with early indica rice without polydextrose, the cooking time was significantly reduced and gruel solids loss was increased with the increase in polydextrose addition. Generalized linear model (GLM) analysis shows that both polydextrose equally reduced the hardness, adhesive force, adhesiveness, cohesiveness, gumminess, and chewiness of the cooked early indica rice, and maintained the resilience. They also significantly reduced the rapid viscosity analysis (RVA) parameters like the peak viscosity, trough viscosity, breakdown viscosity, final viscosity, and setback viscosity of early indica rice, and significantly increased the peak time and pasting temperature. Both polydextrose significantly increased the gelatinization temperature of rice flour measured by a differential scanning calorimeter (DSC)and reduced the gelatinization enthalpy and aging. Compared with the sample without polydextrose, the addition of two types of polydextrose significantly increased the dough development time of rice flour measured by a Mixolab, but reduced the maximum gelatinization torque, starch breakdown and setback torque, and heating rate. XG had a higher capability in decreasing the rice cooking time and the aging of retrograded rice flour paste, and in increasing the score of the appearance structure and taste in cooked rice than ST; ST was better in decreasing the gelatinization enthalpy of rice flour paste and the setback torque of rice dough than XG, maybe due to the polymer molecular weight. Microstructure analysis showed that adding polydextrose promoted the entry of water molecules into the surface of the rice kernel and the dissolution of starch, and the honeycomb structure was gradually destroyed, resulting in larger pores. The cross-section of the cooked rice kernel formed cracks due to the entry of water, the cracks in the IP46 variety were larger and shallower than those in the SRN variety, and there were more filamentous aggregates in the IP46 variety. Polydextrose addition aggravated the swelling of starch granules, made the internal structure loose and produced an obvious depression in the central area of the cross-section, forming soft and evenly swollen rice kernels. These results suggest that polydextrose addition can significantly improve the hard texture of cooked early indica rice and shorten the cooking time. Full article

Single and multiple pull-out properties of a nano-processed para-aramid fabric structure were investigated. The nano pull-out behavior exhibited three distinct regions, namely crimp extension, interlacement rupture, and stick-slip. Multiple yarn pull-out tests demonstrated a significantly higher pull-out force compared to single-yarn pull-out, primarily attributed to the incorporation of nanoparticles. Furthermore, it was observed that an increase in fabric length resulted in an approximately linear increase in both yarn crimp extension and pull-out force. The highest pull-out force was obtained in the nano-hexagonal boron carbide (nh-B₄C, 0.3%) para-aramid structure, followed by multiwalled carbon nanotube (MWCNT, 0.3%) para-aramids. This is because of the enhancement of filament-to-filament friction, especially in the interlacement zone of fabric, alongside the cumulative frictional interactions among the nanoparticles. Additionally, the findings highlight an improvement in crimp extension energy absorption facilitated by nanoparticle incorporation in soft fabric. Notably, the improvement in the energy absorption capacity of yarns within the fabric, without disintegration, is considered significant at this stage. These results indicate a promising potential for performance enhancement in prospective soft ballistic applications. Full article

The endoscopic transsphenoidal approach (ETA) is a novel approach used by neurosurgeons and otolaryngologists to treat pituitary adenoma, and it has a long learning curve. Training is mostly performed using cadaver heads, but their low availability and cost can limit their use. ETA training models can be used to overcome these limitations. In this panorama, additive manufacturing (AM) technologies represent a more flexible and cost-effective solution to fabricate custom-made training models. Their development involves computed tomography (CT) segmentation, STL file elaboration, direct 3D printing, and rapid parts tooling. This work presents and discusses the entire procedure applied to a modular ETA training model. The procedure starts with selecting the material and AM processes based on a literature review. Accordingly, the parts of the model were designed, 3D printed, or rapid cast. In particular, fused filament fabrication (FFF) was adopted for those tissues whose materials could be directly printed (bones and cartilage), while the rapid casting of silicone was adopted for soft tissues (skin and mucosa) together with FFF to fabricate mold patterns and cores. After fabrication and assembly, the model was finally tested by an experienced neurosurgeon who provided feedback. Moreover, the cost and time of the prototype fabrication were assessed. Results validated the proposed solution from both the surgical and commercial points of view. Moreover, general procedures for designing and rapidly fabricating ETA models were generalized to make them exploitable to more general case studies. Full article

Nestin is a type VI intermediate filament protein and a well-known neural stem cell marker. It is also expressed in high-grade cancer cells, forming copolymerized filaments with vimentin. We previously showed that nestin inhibits the binding of vimentin’s tail domain to actin filaments (AFs) by steric hindrance through its large nestin tail domain (NTD), thereby increasing three-dimensional cytoskeleton network mobility, enhancing cell flexibility, and promoting cancer progression. Further, we found that nestin itself stably binds to AFs via the NTD. We therefore hypothesized that the NTD may form a flexible cytoskeletal structure by extending with weak force. In vitro tensile tests using atomic force microscopy were performed to assess the mechanical properties of NTDs. The C-terminus of the NTD bound AFs by bringing the AFM tip modified with the NTD into contact with the AFs on the substrate. NTDs were elongated to approximately 80% of their maximum length at weak forces < 150 pN. Repeated tensile tests revealed that the NTD refolded quickly and behaved like a soft elastic material. We speculate that nestin stably binds AFs, and the NTD extends with weak force, contracting quickly upon load release. Thereby, nestin would absorb mechanical load and maintain cytoskeletal integrity. Full article

Introduction: Gold threads became widely used in esthetic surgery in the early 1990s. Produced in Spain, these threads consisted of a gold thread (5/0) with a diameter of 0.1 mm, composed of 99.99% pure gold, which was combined with a polyglycolic thread. Since then, discussions about their effectiveness have continued, which is the focus of our study. Patients and Methods: Gold thread implantation was performed on 11,062 patients in four clinics in Moscow over the course of 28 years. This study used a comparative analysis of photo collages created for the visual representation of data and changes before and after the procedure, as well as patient satisfaction assessments using the Patient Satisfaction Scale (PSS). We examined the results of 492 patients who underwent gold thread implantation in the face between 1996 and 2024. Of these patients, 86% were women aged 30 to 60 years, 11% were women aged 20 to 30 years, and 3% were men aged 25 to 60 years. Results: One year after thread implantation, the PSS assessment showed a 91% success rate with minimal complications. Patient satisfaction was high, with an average score of 4.8 out of 5 after one month, 4.7 after six months, and 4.6 after one-year post-procedure. Discussion: Gold thread implantation is a minimally invasive procedure that has demonstrated a high level of safety, making it an effective option for facial rejuvenation. Histological studies have shown that gold threads stimulate the production of collagen and elastin and activate angiogenesis, thereby improving skin nourishment and hydration, as well as enhancing the skin tone, elasticity, and turgor. To improve the qualitative characteristics of the skin, it is necessary to work in the subcutaneous layer. Conclusions: Gold thread implantation strengthens the connective tissue framework at the implantation site, thus improving skin nourishment and hydration. Gold threads provide a long-term rejuvenating effect, slowing the ptosis of the soft tissue of the face and neck. Gold thread implantation does not interfere with tissue dissection during surgical interventions or the performance of any cosmetic procedures, including hardware-based treatments. Full article

Water-in-oil microemulsions, as stable colloidal dispersions from quasi-ternary mixtures, have been used in diverse applications, including nanoreactors for confined chemical processes. Their use as soft templates not only includes nanomaterial synthesis but also the interfacial assembly of nanoparticles in hybrid nanostructures. Especially the hierarchical arrangement of different types of nanoparticles over a surface in filament networks constitutes an interesting bottom-up strategy for facile and tunable film coating. Herein, we demonstrate the versatility of this surface assembly from microemulsion dispersions. Transmission and Scanning Electron Microscopy, in addition to UV–Vis Transmittance Spectroscopy, proved the assembly tunability after solvent evaporation under different conditions: the nanostructured films can be formed over different surfaces, using different compositions of liquid phases, as well as with the incorporation of different nanoparticle materials while keeping equivalent surface functionalization. This offers the possibility of adapting different components and conditions for coating tuning on a larger scale with simple procedures. Full article